ORCID Profile
0000-0001-7704-7921
Current Organisation
Westfälische Wilhelms-Universität Münster
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Publisher: The American Association of Immunologists
Date: 11-2013
Abstract: The cell surface heparan sulfate proteoglycan, syndecan-1, has been reported to be a negative regulator of various inflammatory processes, but its precise mode of action is poorly defined. In this study, we use the murine model of the 35–55 peptide of myelin oligodendrocyte glycoprotein–induced experimental autoimmune encephalomyelitis (EAE), a T lymphocyte–mediated inflammation where the steps in disease development and recovery are well characterized, to decipher how syndecan-1 impacts on the inflammatory reaction. Syndecan-1 knockout (Sdc-1−/−) mice show enhanced disease severity and impaired recovery. The use of bone marrow chimeric mice reveals that both an immune cell and a CNS-resident source of syndecan-1 contribute to this phenotype. Epithelial cells of the choroid plexus, where initial CCL20-induced leukocyte recruitment to the brain occurs, are identified as the predominant site of syndecan-1 expression. Syndecan-1 is lost from this site during the course of EAE by shedding into the cerebrospinal fluid, which correlates with loss of epithelial cell surface–bound CCL20 and is associated with the upregulation of IL-6 expression. In Sdc-1−/− mice, early leukocyte recruitment via the choroid plexus is enhanced, and IL-6 is elevated, which collectively results in higher numbers of the disease inducing Th17 cells in the CNS, thereby contributing to enhanced disease severity. Furthermore, Sdc-1−/− mice have intrinsically elevated plasma cell numbers and higher myelin oligodendrocyte glycoprotein–specific Ab levels during EAE, which we propose contributes to impaired recovery. Our data identify the choroid plexus epithelium as a novel source of IL-6 in EAE and demonstrate that its expression negatively correlates with syndecan-1 expression at this site.
Publisher: EMBO
Date: 15-05-2017
Publisher: Elsevier BV
Date: 05-2000
Publisher: Elsevier BV
Date: 07-1992
DOI: 10.1016/0014-4827(92)90357-E
Abstract: Rat monoclonal antibodies were raised against fragment E3 of the mouse Engelbreth-Holm-Swarm (EHS) tumor laminin and selected according to their exclusive reaction with laminin A chain by immunoblotting and staining pattern in embryonic kidneys by immunofluorescence. Immunochemical studies of nine purified antibodies showed a comparable reaction with unfragmented laminin and fragment E3 but no cross-reaction with several other, unrelated laminin fragments including the major cell-binding fragment E8. Reduction or pepsin digestion of fragment E3 reduced or abolished antibody binding indicating that most of the epitopes involved are conformation dependent and do not include carbohydrates. They are, however, not identical as shown by different reactivities after proteolytic or chemical cleavage of E3. Four of the antibodies were highly active in inhibiting cell adhesion of the teratocarcinoma cell line F9 and the Schwannoma cell line RN22 on fragment E3 (IC50 approximately 1 microgram/ml), while the others were distinctly less active. No inhibition was observed for cell adhesion on unfragmented laminin, consistent with previous findings that this is largely mediated by binding of fragment E8 to alpha 6 beta 1 integrin. A distinct correlation was observed between cell adhesion inhibition and the inhibition of heparansulfate proteoglycan and heparin binding to fragment E3. Since heparin is not very efficient in inhibiting cell adhesion, it indicates that heparin- and cell-binding sites on fragment E3 are in close proximity but not identical. Two of the antibodies also showed partial inhibition of kidney tubule formation in organ culture of embryonic kidney mesenchyme while the other antibodies were inactive. It suggests some but probably minor involvement of the fragment E3 structure of laminin in this developmental process.
Publisher: Springer Science and Business Media LLC
Date: 25-09-2009
DOI: 10.1007/S00281-009-0177-0
Abstract: The central nervous system (CNS) is tightly sealed from the changeable milieu of blood by the blood-brain barrier (BBB) and the blood-cerebrospinal fluid (CSF) barrier (BCSFB). While the BBB is considered to be localized at the level of the endothelial cells within CNS microvessels, the BCSFB is established by choroid plexus epithelial cells. The BBB inhibits the free paracellular diffusion of water-soluble molecules by an elaborate network of complex tight junctions (TJs) that interconnects the endothelial cells. Combined with the absence of fenestrae and an extremely low pinocytotic activity, which inhibit transcellular passage of molecules across the barrier, these morphological peculiarities establish the physical permeability barrier of the BBB. In addition, a functional BBB is manifested by a number of permanently active transport mechanisms, specifically expressed by brain capillary endothelial cells that ensure the transport of nutrients into the CNS and exclusion of blood-borne molecules that could be detrimental to the milieu required for neural transmission. Finally, while the endothelial cells constitute the physical and metabolic barrier per se, interactions with adjacent cellular and acellular layers are prerequisites for barrier function. The fully differentiated BBB consists of a complex system comprising the highly specialized endothelial cells and their underlying basement membrane in which a large number of pericytes are embedded, perivascular antigen-presenting cells, and an ensheathment of astrocytic endfeet and associated parenchymal basement membrane. Endothelial cell morphology, biochemistry, and function thus make these brain microvascular endothelial cells unique and distinguishable from all other endothelial cells in the body. Similar to the endothelial barrier, the morphological correlate of the BCSFB is found at the level of unique apical tight junctions between the choroid plexus epithelial cells inhibiting paracellular diffusion of water-soluble molecules across this barrier. Besides its barrier function, choroid plexus epithelial cells have a secretory function and produce the CSF. The barrier and secretory function of the choroid plexus epithelial cells are maintained by the expression of numerous transport systems allowing the directed transport of ions and nutrients into the CSF and the removal of toxic agents out of the CSF. In the event of CNS pathology, barrier characteristics of the blood-CNS barriers are altered, leading to edema formation and recruitment of inflammatory cells into the CNS. In this review we will describe current knowledge on the cellular and molecular basis of the functional and dysfunctional blood-CNS barriers with focus on CNS autoimmune inflammation.
Publisher: Bentham Science Publishers Ltd.
Date: 04-2009
DOI: 10.2174/138161209787846685
Abstract: Extracellular matrix (ECM) provides a physical scaffold for cells but also provides specific molecular and spatial information that influences cell proliferation, differentiation and apoptosis. This review addresses the multiple roles of ECM in inflammatory responses, in particular in leukocyte extravasation at sites of inflammation, and the potential of exploiting such cell-ECM interactions to interfere with defined steps in the inflammatory process. In the course of an inflammation leukocytes not only have to penetrate the vascular endothelial cell monolayer, but also the underlying endothelial cell basement membrane and invade the interstitial matrix of the stroma to reach the site of inflammation. The endothelial cell basement membrane may directly influence leukocyte recruitment to the inflammed tissue by providing differential signals resulting from its spatial and molecular composition, or indirectly by its potential to bind and present cytokines or chemotactic factors. Proteases (in particular matrix metalloproteinases (MMP)) released at sites of inflammation selectively process ECM and cell surface molecules, which may result in the release of bioactive fragments that may function as chemoattractants for different leukocytes subsets or modulate the activity/ function of resident mesenchymal and immune cells. In addition, MMPs have been shown to process chemokines modulating their chemoattractant properties. To be able to mimic or inhibit some of the ECM functions or proteolytic events that occur during inflammation, through the use of specific protein fragments, would provide a means by which the inflammatory process could be manipulated, an area however that remains largely unexplored.
Publisher: Elsevier BV
Date: 2005
DOI: 10.1016/J.IMMUNI.2004.11.013
Abstract: Resident dendritic cells (DC) within the T cell area of the lymph node take up soluble antigens that enter via the afferent lymphatics before antigen carrying DC arrive from the periphery. The reticular network within the lymph node is a conduit system forming the infrastructure for the fast delivery of soluble substances from the afferent lymph to the lumen of high endothelial venules (HEVs). Using high-resolution light microscopy and 3D reconstruction, we show here that these conduits are unique basement membrane-like structures ensheathed by fibroblastic reticular cells with occasional resident DC embedded within this cell layer. Conduit-associated DC are capable of taking up and processing soluble antigens transported within the conduits, whereas immigrated mature DC occur remote from the reticular fibers. The conduit system is, therefore, not a closed compartment that shuttles substances through the lymph node but represents the morphological equivalent to the filtering function of the lymph node.
Publisher: Rockefeller University Press
Date: 03-04-2006
DOI: 10.1084/JEM.20051342
Abstract: The endothelial cell monolayer of cerebral vessels and its basement membrane (BM) are ensheathed by the astrocyte endfeet, the leptomeningeal cells, and their associated parenchymal BM, all of which contribute to establishment of the blood–brain barrier (BBB). As a consequence of this unique structure, leukocyte penetration of cerebral vessels is a multistep event. In mouse experimental autoimmune encephalomyelitis (EAE), a widely used central nervous system inflammatory model, leukocytes first penetrate the endothelial cell monolayer and underlying BM using integrin β1-mediated processes, but mechanisms used to penetrate the second barrier defined by the parenchymal BM and glia limitans remain uninvestigated. We show here that macrophage-derived gelatinase (matrix metalloproteinase [MMP]-2 and MMP-9) activity is crucial for leukocyte penetration of the parenchymal BM. Dystroglycan, a transmembrane receptor that anchors astrocyte endfeet to the parenchymal BM via high affinity interactions with laminins 1 and 2, perlecan and agrin, is identified as a specific substrate of MMP-2 and MMP-9. Ablation of both MMP-2 and MMP-9 in double knockout mice confers resistance to EAE by inhibiting dystroglycan cleavage and preventing leukocyte infiltration. This is the first description of selective in situ proteolytic damage of a BBB-specific molecule at sites of leukocyte infiltration.
Publisher: Wiley
Date: 12-1988
Abstract: The experiments described in this study were designed to investigate receptor-mediated endocytosis of transferrin and its role in iron uptake by cultured chick presumptive myoblasts ( iding and non- iding) and myotubes. The effects of a variety of inhibitors on the internalization of transferrin and iron were investigated and three main effects were found: (i) sulphydryl reagents and microtubular inhibitors reduced the rate of transferrin and iron internalization to similar degrees, (ii) metabolic inhibitors reduced the rate of iron uptake more than that of transferrin endocytosis, and (iii) lysosomotrophic agents almost completely abolished iron accumulation by the cells without any effect on the rate of transferrin internalization. The results suggest that metabolic energy is required not only for the endocytosis of transferrin but also for subsequent steps in the iron uptake process, and that iron release from transferrin occurs in acidified endosomes. Overall, these experiments show that all or virtually all of the iron taken up by developing muscle cells from transferrin occurs as a consequence of receptor-mediated endocytosis of the protein.
Publisher: Springer Science and Business Media LLC
Date: 09-05-2010
DOI: 10.1038/NM.2150
Abstract: Mechanisms linking innate immunity and autoimmune responses are poorly understood. Myeloid-related protein-8 (Mrp8) and Mrp14 are damage-associated molecular pattern molecules (DAMPs) highly upregulated in various autoimmune disorders. We show in a mouse autoimmune model that local Mrp8 and Mrp14 production is essential for the induction of autoreactive CD8+ T cells and the development of systemic autoimmunity. This effect is mediated via Toll-like receptor 4 (TLR4) signaling leading to increased interleukin-17 (IL-17) expression. Notably, expression of Mrp8 and Mrp14 was upregulated in cutaneous lupus erythematosus, and stimulation of CD8+ T cells from in iduals with lupus erythematosus with MRP proteins resulted in an upregulation of IL-17, suggesting a key role for MRP8 and MRP14 for the development of autoreactive lymphocytes during human autoimmunity as well. These results demonstrate a link between local expression of DAMP molecules and the development of systemic autoimmunity.
Publisher: Springer Science and Business Media LLC
Date: 27-12-2012
Publisher: Wiley
Date: 31-05-2005
DOI: 10.1111/J.1600-0838.2005.00467.X
Abstract: Mechanical force is generated within skeletal muscle cells by contraction of specialized myofibrillar proteins. This paper explores how the contractile force generated at the sarcomeres within an in idual muscle fiber is transferred through the connective tissue to move the bones. The initial key point for transfer of the contractile force is the muscle cell membrane (sarcolemma) where force is transferred laterally to the basement membrane (specialized extracellular matrix rich in laminins) to be integrated within the connective tissue (rich in collagens) before transmission to the tendons. Connections between (1) key molecules outside the myofiber in the basement membrane to (2) molecules within the sarcolemma of the myofiber and (3) the internal cytoplasmic structures of the cytoskeleton and sarcomeres are evaluated. Disturbances to many components of this complex interactive system adversely affect skeletal muscle strength and integrity, and can result in severe muscle diseases. The mechanical aspects of these crucial linkages are discussed, with particular reference to defects in laminin-alpha2 and integrin-alpha7. Novel interventions to potentially increase muscle strength and reduce myofiber damage are mentioned, and these are also highly relevant to muscle diseases and aging muscle.
Publisher: Informa UK Limited
Date: 2013
DOI: 10.4161/CAM.22680
Publisher: Elsevier BV
Date: 10-1988
Publisher: American Society of Hematology
Date: 20-06-2019
Abstract: Maintenance of tumor vasculature integrity is indispensable for tumor growth and thus affects tumor progression. Previous studies have identified platelets as major regulators of tumor vascular integrity, as their depletion selectively rendered tumor vessels highly permeable and caused massive intratumoral hemorrhage. While these results established platelets as potential targets for antitumor therapy, their depletion is not a treatment option due to their essential role in hemostasis. Thus, a detailed understanding of how platelets safeguard vascular integrity in tumors is urgently demanded. Here, we show for the first time that functional inhibition of glycoprotein VI (GPVI) on the platelet surface with an antibody (JAQ1) F(ab)2 fragment rapidly induces tumor hemorrhage and diminishes tumor growth similar to complete platelet depletion while not inducing systemic bleeding complications. The intratumor bleeding and tumor growth arrest could be reverted by depletion of Ly6G+ cells, confirming them to be responsible for the induction of bleeding and necrosis within the tumor. In addition, JAQ1 F(ab)2–mediated GPVI inhibition increased intratumoral accumulation of coadministered chemotherapeutic agents, such as Doxil and paclitaxel, thereby resulting in a profound antitumor effect. In summary, our findings identify platelet GPVI as a key regulator of vascular integrity specifically in growing tumors and could serve as a basis for the development of antitumor strategies based on the interference with platelet function.
Publisher: American Society for Clinical Investigation
Date: 18-05-2020
DOI: 10.1172/JCI99027
Publisher: Elsevier BV
Date: 04-2005
Publisher: American Diabetes Association
Date: 14-06-2013
DOI: 10.2337/DB13-ER07
Publisher: Elsevier BV
Date: 12-2007
DOI: 10.1016/J.EXER.2007.08.020
Abstract: A specialized microenvironment or niche, which regulates maintenance, self-renewal, activation, and proliferation of stem cells by external signals, is one of the key prerequisites for stem cell function. However, the parameters determining the limbal stem cell niche are not yet defined. In order to characterize the role of basement membrane (BM) and extracellular matrix components in the generation of a microenvironmental niche for limbal stem and progenitor cells, we extensively analyzed the topographical variations of the BM zone of human ocular surface epithelia using immunohistochemistry and a large panel of antibodies to most of the presently described intrinsic and associated BM components. Apart from BM components uniformly expressed throughout all ocular surface epithelia (e.g. type IV collagen alpha5 and alpha6 chains, collagen types VII, XV, XVII, and XVIII, laminin-111, laminin-332, laminin chains alpha3, beta3,and gamma2, fibronectin, matrilin-2 and -4, and perlecan), the BM of the limbal epithelium shared many similarities with that of the conjunctival epithelium, including positive labelling for type IV collagen alpha1 and alpha2 chains, laminin alpha5, beta2, and gamma1 chains, nidogen-1 and -2, and thrombospondin-4, whereas type IV collagen alpha3, type V collagen, fibrillin-1 and -2, thrombospondin-1, and endostatin were present in the corneal BM, but lacking or more weakly expressed in the limbal and conjunctival BMs. As compared to both the corneal and conjunctival BMs, the limbal BM showed a markedly increased immunoreactivity for laminin alpha1, alpha2, beta1 chains, and agrin, and a specific but patchy immunoreactivity for laminin gamma3 chain, BM40/SPARC, and tenascin-C, which co-localized with ABCG2 63/K19-positive and K3/Cx43/desmoglein/integrin-alpha2-negative cell clusters comprising putative stem and early progenitor cells in the basal epithelium of the limbal palisades. Components that were particularly expressed in the corneal-limbal transition zone included type XVI collagen, fibulin-2, tenascin-C/R, vitronectin, bamacan, chondroitin sulfate, and versican, all of which co-localized with vimentin-positive cell clusters comprising putative late progenitor cells in the basal epithelium. This pronounced heterogeneity of the BM in the limbal area, both in the region of limbal palisades and the corneal-limbal transition zone, appears to be involved in providing unique microenvironments for corneal epithelial stem and late progenitor cells. Identification of specific niche parameters might not only help to understand limbal stem cell regulation, but also to improve their selective enrichment and in vitro expansion for therapeutic strategies.
Publisher: Oxford University Press (OUP)
Date: 26-07-2006
Abstract: Extracellular matrix regulates many cellular processes likely to be important for development and regression of corpora lutea. Therefore, we identified the types and components of the extracellular matrix of the human corpus luteum at different stages of the menstrual cycle. Two different types of extracellular matrix were identified by electron microscopy subendothelial basal laminas and an interstitial matrix located as aggregates at irregular intervals between the non-vascular cells. No basal laminas were associated with luteal cells. At all stages, collagen type IV alpha1 and laminins alpha5, beta2 and gamma1 were localized by immunohistochemistry to subendothelial basal laminas, and collagen type IV alpha1 and laminins alpha2, alpha5, beta1 and beta2 localized in the interstitial matrix. Laminin alpha4 and beta1 chains occurred in the subendothelial basal lamina from mid-luteal stage to regression at earlier stages, a punctate pattern of staining was observed. Therefore, human luteal subendothelial basal laminas potentially contain laminin 11 during early luteal development and, additionally, laminins 8, 9 and 10 at the mid-luteal phase. Laminin alpha1 and alpha3 chains were not detected in corpora lutea. Versican localized to the connective tissue extremities of the corpus luteum. Thus, during the formation of the human corpus luteum, remodelling of extracellular matrix does not result in basal laminas as present in the adrenal cortex or ovarian follicle. Instead, novel aggregates of interstitial matrix of collagen and laminin are deposited within the luteal parenchyma, and it remains to be seen whether this matrix is important for maintaining the luteal cell phenotype.
Publisher: Elsevier BV
Date: 05-1997
DOI: 10.1016/S0960-8966(97)00425-2
Abstract: Approximately half the cases of classical congenital muscular dystrophy (CMD) have a pronounced deficiency or absence of the laminin alpha 2 chain of laminin-2 (merosin). This is caused by mutations in the LAMA2 gene that codes for laminin alpha 2, and all informative cases so far studied show linkage to the appropriate region on chromosome 6q. Most CMD patients with a deficiency of laminin alpha 2 have a severe phenotype that involves skeletal muscle, and the central and peripheral nervous system. We have identified four cases that have minimal reduction of laminin alpha 2 using a commercial antibody that only recognises a C-terminal 80 kDa fragment, but show a pronounced reduction using an antibody to the 300 kDa fragment. Haplotype analysis is compatible with linkage to the LAMA2 locus in three informative families, whilst the fourth family was not informative. Two of the affected children are ambulant and have a mild phenotype. The third case is unusual in having severe muscle weakness but does not show the white matter changes on magnetic resonance imaging of the brain that is usually seen in merosin-deficient cases of CMD the fourth case has a severe phenotype, typical of merosin-deficient patients but shows good immunolabelling of the 80 kDa fragment of laminin alpha 2, corresponding to the C-terminal region. Our data show that there is a broad spectrum of phenotype and protein expression associated with a primary deficiency in laminin alpha 2, and that a wider range of clinical cases need to be screened for a deficiency of merosin. It is also important to study the expression of laminin alpha 2 with more than one antibody.
Publisher: Springer Science and Business Media LLC
Date: 21-08-2009
DOI: 10.1007/S00441-009-0853-3
Abstract: The extracellular matrix (ECM) exists in various biochemical and structural forms that can act either as a barrier to migrating leukocytes, in the case of basement membranes, or provide a physical scaffold supporting or guiding migration (interstitial matrix). This review focuses on basement membranes and our current knowledge of the way that leukocytes transmigrate this protein barrier, with emphasis on T lymphocytes. Recent data suggest that the classical concept of cell-matrix adhesion requires revision with respect to leukocyte-ECM interactions. Whereas specific receptors may be required for leukocyte recognition of ECM molecules or three-dimensional structural domains, the role of adhesion in migration as perceived from the traditional studies of adherent cell-ECM interactions is less clear. Further, the indirect effects of ECM such as the binding and presentation of cytokines or chemotactic factors may more profoundly influence the directed migration of normally non-adherent leukocytes than the migration of adherent cells such as epithelial cells or fibroblasts. Proteases (in particular matrix metalloproteinases) released at sites of inflammation can selectively process ECM, cell surface molecules or soluble factors, which may result in the release of bioactive fragments that can function as chemoattractants for different leukocyte subsets or may modulate the activity/function of resident mesenchymal and immune cells. Current findings suggest that different leukocyte types employ different mechanisms to migrate across or through the ECM this might be determined by the composition and organization of the ECM itself.
Publisher: Elsevier BV
Date: 03-1209
DOI: 10.1016/S0022-510X(99)00012-X
Abstract: The integrins are a large family of heterodimeric transmembrane cellular receptors which mediate the association between the extracellular matrix (ECM) and cytoskeletal proteins. The alpha7beta1 integrin is a major laminin binding integrin in skeletal and cardiac muscle and is thought to be involved in myogenic differentiation and migration processes. The main binding partners of the alpha7 integrin are laminin-1 (alpha1-beta1-gamma1), laminin-2 (alpha2-beta1-gamma1) and laminin-4 (alpha2-beta2-gamma1). Targeted deletion of the gene for the alpha7 integrin subunit (ITGA7) in mice leads to a novel form of muscular dystrophy. In the present study we have investigated the expression of two alternative splice variants, the alpha7B and beta1D integrin subunits, in normal human skeletal muscle, as well as in various forms of muscular dystrophy. In normal human skeletal muscle the expression of the alpha7 integrin subunit appeared to be developmentally regulated: it was first detected at 2 years of age. In contrast, the beta1D integrin could be detected in immature and mature muscle in the sarcolemma of normal fetal skeletal muscle at 18 weeks gestation. The expression of alpha7B integrin was significantly reduced at the sarcolemma in six patients with laminin alpha2 chain deficient congenital muscular dystrophy (CMD) (age >2 years). However, this reduction was not correlated with the amount of laminin alpha2 chain expressed. In contrast, the expression of the laminin alpha2 chain was not altered in the skeletal muscle of the alpha7 knock-out mice. These data argue in favor that there is not a tight correlation between the expression of the alpha7 integrin subunit and that of the laminin alpha2 chain in either human or murine dystrophic muscle. Interestingly, in dystrophinopathies (Duchenne and Becker muscular dystrophy DMD/BMD) expression of alpha7B was upregulated irrespective of the level of dystrophin expression as shown by a strong sarcolemmal staining pattern even in young boys (age <2 years). The expression of the beta1D integrin subunit was not altered in any of our patients with different types of muscular dystrophy. In contrast, sarcolemmal expression of beta1D integrin was significantly reduced in the alpha7 integrin knock-out mice, whereas the expression of the components of the DGC was not altered. The secondary loss of alpha7B in laminin alpha2 chain deficiency defines a biochemical change in the composition of the plasma membrane resulting from a primary protein deficiency in the basal lamina. These findings, in addition to the occurrence of a muscular dystrophy in alpha7 deficient mice, implies that the alpha7B integrin is an important laminin receptor within the plasma membrane which plays a significant role in skeletal muscle function and stability.
Publisher: American Society of Hematology
Date: 19-08-2010
DOI: 10.1182/BLOOD-2009-12-256388
Abstract: Leukocyte extravasation depends on various adhesion receptors at endothelial cell contacts. Here we have analyzed how mouse CD99 and CD99L2 cooperate with PECAM-1. We found that antibodies against mouse CD99 and PECAM-1 trap neutrophils between endothelial cells in in vitro transmigration assays. A sequential function, as has been suggested for human PECAM-1 and CD99, could not be demonstrated. In contrast to these in vitro results, blocking CD99 or CD99L2 or gene disruption of PECAM-1 trapped neutrophils in vivo between endothelial cells and the underlying basement membrane as revealed by electron microscopy and by 3-dimensional confocal fluorescence microscopy in the inflamed cremaster tissue. Leukocyte extravasation was inhibited in interleukin-1β-inflamed peritoneum and in the cremaster by PECAM-1 gene disruption and was further attenuated by blocking antibodies against CD99 and CD99L2. In addition, CD99 and CD99L2 were required for leukocyte extravasation in the cremaster after stimulation with tumor necrosis factor-α, where the need for PECAM-1 is known to be bypassed. We conclude that CD99 and CD99L2 act independently of PECAM-1 in leukocyte extravasation and cooperate in an independent way to help neutrophils overcome the endothelial basement membrane.
Publisher: Proceedings of the National Academy of Sciences
Date: 03-09-2021
Abstract: The meninges protect the central nervous system but also host lymphocytes in neuroinflammation. In human multiple sclerosis, preferentially B cells accumulate in the meninges. By generating a compartment-specific transcriptional map of meningeal versus parenchymal leukocytes in experimental neuroinflammation, we found a follicular phenotype of meningeal B cells and a corresponding follicular helper-like phenotype in meningeal Th17 cells. The meninges thus instructed a site-specific local phenotype to proinflammatory autoreactive T cells. We identified the transcription factor Bcl6 in Th17 cells to promote interactions with meningeal B cells, isotype-switching, and B cell-supporting chemokines. This may describe a mechanism controlling meningeal autoimmunity and helps understanding how the meninges, as a recently recognized immunologically active site, contribute to autoimmune tissue damage in multiple sclerosis.
Publisher: Springer Science and Business Media LLC
Date: 24-09-2010
DOI: 10.1038/NRI2852
Abstract: The advent of in situ immunology and intravital analyses of leukocyte movement in tissues has drawn attention to the previously neglected extracellular matrix (ECM) and its role in modulating immune cell behaviour in inflamed tissues. The ECM exists in different biochemical and structural forms both their in idual components and three-dimensional ultrastructure impart specific signals to cells that modulate basic functions that are important for the early steps in inflammation, such as immune cell migration into inflamed tissues and immune cell differentiation. In chronically inflamed tissues, aberrant ECM expression and fragments of the ECM that are derived from tissue-remodelling processes can influence immune cell activation and survival, thereby actively contributing to immune responses at these sites.
Publisher: American Diabetes Association
Date: 17-01-2013
DOI: 10.2337/DB12-0432
Abstract: We provide the first comprehensive analysis of the extracellular matrix (ECM) composition of peri-islet capsules, composed of the peri-islet basement membrane (BM) and subjacent interstitial matrix (IM), in development of type 1 diabetes in NOD mice and in human type 1 diabetes. Our data demonstrate global loss of peri-islet BM and IM components only at sites of leukocyte infiltration into the islet. Stereological analyses reveal a correlation between incidence of insulitis and the number of islets showing loss of peri-islet BM versus islets with intact BMs, suggesting that leukocyte penetration of the peri-islet BM is a critical step. Protease- and protease inhibitor–specific microarray analyses (CLIP-CHIP) of laser-dissected leukocyte infiltrated and noninfiltrated pancreatic islets and confirmatory quantitative real time PCR and protein analyses identified cathepsin S, W, and C activity at sites of leukocyte penetration of the peri-islet BM in association with a macrophage subpopulation in NOD mice and human type 1 diabetic s les and, hence, potentially a novel therapeutic target specifically acting at the islet penetration stage. Interestingly, the peri-islet BM and underlying IM are reconstituted once inflammation subsides, indicating that the peri-islet BM-producing cells are not lost due to the inflammation, which has important ramifications to islet transplantation studies.
Publisher: Elsevier BV
Date: 05-2011
Publisher: Elsevier BV
Date: 11-2008
DOI: 10.1016/J.IMBIO.2008.07.025
Abstract: Langerhans cells and dermal dendritic cells migrate to the draining lymph nodes through dermal lymphatic vessels. They do so in the steady-state and under inflammatory conditions. Peripheral T cell tolerance or T cell priming, respectively, are the consequences of migration. The nature of dendritic cell-containing vessels was mostly defined by electron microscopy or by their lack of blood endothelial markers. Selective markers for murine lymph endothelium were hitherto rare or not available. Here, we utilised recently developed antibodies against the murine hyaluronan receptor, LYVE-1, to study the lymph vessel network in mouse skin in more detail. In hairless skin from the ears, lymph vessels were spread out in a horizontal plane. They formed anastomoses, and they possessed frequent blind endings that were occasionally open. Lymph vessels were wider than blood vessels, which were identified by their strong CD31 expression. In body wall skin LYVE-1 reactive vessels did not extend laterally but they ed straight down into the deeper dermis. There, they are connected to each other and formed a network similar to ear skin. The number and width of lymph vessels did not grossly change upon inflammatory stimuli such as skin explant culture or tape stripping. There were also no marked changes in caliber in response to the TLR 7/8 ligand Imiquimod. Double-labelling experiments of cultured skin showed that most of the strongly cell surface MHC II-expressing (i.e. activated) dendritic cells were confined to the lymph vessels. Langerin/CD207(+) cells within this population appeared later than dermal dendritic cells, i.e. langerin-negative cells. Comparable results were obtained after stimulating the skin in vivo with the TLR 7/8 ligand Imiquimod or by tape stripping. In untreated skin (i.e. steady state) a few MHC II(+) and Langerin/CD207(+) cells, presumably migrating skin dendritic cells including epidermal Langerhans cells, were consistently observed within the lymph vessels. The novel antibody reagents may serve as important tools to further study the dendritic cell traffic in the skin under physiological conditions as well as in conditions of adoptive dendritic cell transfer in immunotherapy.
Publisher: American Physiological Society
Date: 07-2005
DOI: 10.1152/PHYSREV.00014.2004
Abstract: Endothelial cells of the blood and lymphatic vasculature are polarized cells with luminal surfaces specialized to interact with inflammatory cells upon the appropriate stimulation they contain specialized transcellular transport systems, and their basal surfaces are attached to an extracellular basement membrane. In adult tissues the basement membrane forms a continuous sleeve around the endothelial tubes, and the interaction of endothelial cells with basement membrane components plays an important role in the maintenance of vessel wall integrity. During development, the basement membrane of endothelium provides distinct spatial and molecular information that influences endothelial cell proliferation, migration, and differentiation/maturation. Microvascular endothelium matures into phenotypically distinct types: continuous, fenestrated, and discontinuous, which also differ in their permeability properties. Development of these morphological and physiological differences is thought to be controlled by both soluble factors in the organ or tissue environment and by cell-cell and cell-matrix interactions. Basement membranes of endothelium, like those of other tissues, are composed of laminins, type IV collagens, heparan sulfate proteoglycans, and nidogens. However, isoforms of all four classes of molecules exist, which combine to form structurally and functionally distinct basement membranes. The endothelial cell basement membranes have been shown to be unique with respect to their laminin isoform composition. Laminins are a family of glycoprotein heterotrimers composed of an α, β, and γ chain. To date, 5α, 4β, and 3γ laminin chains have been identified that can combine to form 15 different isoforms. The laminin α-chains are considered to be the functionally important portion of the heterotrimers, as they exhibit tissue-specific distribution patterns and contain the major cell interaction sites. Vascular endothelium expresses only two laminin isoforms, and their expression varies depending on the developmental stage, vessel type, and the activation state of the endothelium. Laminin 8 (composed of laminin α4, β1, and γ1 chains) is expressed by all endothelial cells regardless of their stage of development, and its expression is strongly upregulated by cytokines and growth factors that play a role in inflammatory events. Laminin 10 (composed of laminin α5, β1, and γ1 chains) is detectable primarily in endothelial cell basement membranes of capillaries and venules commencing 3–4 wk after birth. In contrast to laminin 8, endothelial cell expression of laminin 10 is upregulated only by strong proinflammatory signals and, in addition, angiostatic agents such as progesterone. Other extracellular matrix molecules, such as BM40 (also known as SPARC/osteonectin), thrombospondins 1 and 2, fibronectin, nidogens 1 and 2, and collagen types VIII, XV, and XVIII, are also differentially expressed by endothelium, varying with the endothelium type and/or pathophysiological state. The data argue for a dynamic endothelial cell extracellular matrix that presents different molecular information depending on the type of endothelium and/or physiological situation. This review outlines the unique structural and functional features of vascular basement membranes, with focus on the endothelium and the laminin family of glycoproteins.
Publisher: Springer US
Date: 2007
Publisher: Elsevier BV
Date: 06-2001
Publisher: Elsevier BV
Date: 05-2023
Publisher: Wiley
Date: 07-1994
DOI: 10.1111/J.1432-1033.1994.TB19031.X
Abstract: Laminin expression was studied in endothelial cells derived from different mouse tissues and primary cultures of bovine aortic endothelium (BAEC). Immunoprecipitation with polyclonal anti-laminin-1 revealed two 200-kDa chains, a novel 400-kDa chain and nidogen in all cells studied. Two-dimensional electrophoresis of laminin complexes immunoprecipitated from endothelial-cell-conditioned medium demonstrated that the 400-kDa chain was disulphide-linked to the laminin beta 1 and gamma 1 chains. In addition, rotary shadowing illustrated the secretion of molecules from the endothelial cells which were morphologically similar to laminin-1. Immunoblotting and Northern blot analysis confirmed the presence of beta 1 and gamma 1 polypeptides and the corresponding LamB1 and LamC1 mRNAs in all cells investigated. However, both polyclonal anti-laminin-1 and alpha 1-specific monoclonal antibodies failed to react with the 400-kDa polypeptide in immunoblots and immunoprecipitations. Similarly, the expression of the gene coding for alpha 1, LamA1, was not detected in the majority of cells by Northern blot analysis using three different cDNAs. Only in two cases, BAEC and a Simian-virus-40-transformed mouse endothelial cell line (SVEC), a 10-kb mRNA was detected by Northern analysis using a cDNA specific for the 3' coding region (LAC) of LamA1 mRNA. However, cDNAs specific for the central and 5' coding region of LamA1 mRNA did not show any reaction. Hybridization of LAC to BAEC and SVEC mRNA is consistent with the laminin-like nature of the 400-kDa chain expressed by these cells. The results demonstrate the existence of at least one and possibly two novel 400-kDa laminin chains which complex with beta 1 and gamma 1 and occur in mouse and bovine endothelial cell basement membranes.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-1993
DOI: 10.1097/00041552-199307000-00002
Abstract: Over the past year, there have been major advances in the descriptive analysis of the extracellular matrix in the kidney. Several aspects of the interaction of matrix molecules with renal and, in particular with glomerular cells via specific integrin receptors, have also been studied. Most results on cell-matrix interactions have been obtained by in vitro investigations of glomerular mesangial cells in two-dimensional culture. The regulation of matrix formation and degradation has been shown to involve the concerted action of several soluble factors, notably transforming growth factor-beta, as well as the effects of nonsoluble matrix components themselves, such as collagens and proteoglycans. The mediation of such complex interactions between cells, matrix, and cytokines is facilitated by the tightly regulated expression of cell surface receptors, eg, cytokine receptors and integrins of the beta 1 series, which bind specific matrix molecules. New results have yielded more insight into the regulation not only of matrix formation but also of the specific interactions between cells and matrix and of the modulation of cytokine activity by matrix molecules. Using experimental rat models and transgenic mouse models of kidney disease, the first in vivo findings using immunohistochemistry and mRNA analysis have confirmed that major changes occur in the expression of matrix molecules, integrins, and cytokines in the process of glomerular inflammation. With the advent of specific modulators of the bioactivity of ligands and receptors, it is hoped that more information will be forthcoming on the functional relevance of various components of the cell-matrix-cytokine crosstalk in the normal and injured kidney.
Publisher: Elsevier BV
Date: 02-2008
DOI: 10.1016/J.SMIM.2007.12.009
Abstract: Until recently little information was available on the molecular details of the extracellular matrix (ECM) of secondary lymphoid tissues. There is now growing evidence that these ECMs are unique structures, combining characteristics of basement membranes and interstitial or fibrillar matrices, resulting in scaffolds that are strong and highly flexible and, in certain secondary lymphoid compartments, also forming conduit networks for rapid fluid transport. This review will address the structural characteristics of the ECM of the murine spleen and its potential role as an organizer of immune cell compartments, with reference to the lymph node where relevant.
Publisher: American Society for Clinical Investigation
Date: 09-2004
DOI: 10.1172/JCI22104
Publisher: Elsevier BV
Date: 06-2016
DOI: 10.1016/0016-5085(92)90303-G
Abstract: The production of laminin by 14-day fetal rat intestinal endoderm and mesenchyme was investigated. The amount of neosynthesized laminin was measured after purification using affinity chromatography. Chain composition of laminin was analyzed by immunoblotting and immunofluorescence staining. The data show that both embryonic intestinal tissue components synthesize laminin and that A and B1/B2 chains were detected in both endodermal and mesenchymal cells. The cellular source of laminin found at the epithelial basement membrane has been studied by immunocytochemistry in rat/chick or mouse/chick interspecies hybrid intestines taken at various stages of development. Immunodetection of the whole laminin molecule and of the in idual A and B1/B2 chains by rodent-specific polyclonal and monoclonal antibodies at the basement membrane level in these hybrid intestines revealed (a) laminin molecules, which originate from both mesenchymal and endodermal cells (b) deposition of A and B1/B2 chains by endodermal cells, regardless of the stage of growth of the hybrid intestines and (c) asynchronous deposition of the various chains of laminin into the basement membrane by the mesenchyme. B1/B2 chains are deposited concomitant with contact with the epithelium, whereas A chains appear only later (13 days after grafting). These data reinforce the suggestion from previous studies that cooperation between epithelium and mesenchyme is necessary for the formation of a complete basement membrane in the developing intestine.
Publisher: Wiley
Date: 02-05-2021
Abstract: Mesenchymal stromal cells (MSCs) function as a formidable regulator of inflammation and tissue homeostasis and expanded MSCs are shown to be effective in treating various inflammatory diseases. Their therapeutic effects require the existence of certain inflammatory cytokines. However, in the absence of sufficient proinflammatory stimuli or in the presence of anti‐inflammatory medications, MSCs are animated to promote immune responses and unable to alleviate inflammatory disorders. In this study, it is demonstrated that steroid co‐administration interferes the efficacy of MSCs in treating acute graft‐versus‐host disease (aGvHD). Molecular analysis reveals that vascular endothelial growth factor C (VEGF‐C) is highly induced in MSCs by steroids and TNF α and VEGF‐C in turn promotes CD8 + T cell response. This immune promoting effect is abolished by blockade or specific genetic ablation of VEGFR3 in CD8 + T cells. Additionally, administration of VEGF‐C alone exacerbates aGvHD progression through eliciting more vigorous CD8 + T cell activation and proliferation. Further studies demonstrate that VEGF‐C augments the PI3K/AKT signaling process and the expression of downstream genes, such as Cyclin D1. Thus, the data demonstrate that steroids can reverse the immunosuppressive effect of MSCs via promoting VEGF‐C‐augmented CD8 + T cell response and provide novel information for designing efficacious MSC‐based therapies.
Publisher: Rockefeller University Press
Date: 21-05-2001
Abstract: An active involvement of blood–brain barrier endothelial cell basement membranes in development of inflammatory lesions in the central nervous system (CNS) has not been considered to date. Here we investigated the molecular composition and possible function of the extracellular matrix encountered by extravasating T lymphocytes during experimental autoimmune encephalomyelitis (EAE). Endothelial basement membranes contained laminin 8 (α4β1γ1) and/or 10 (α5β1γ1) and their expression was influenced by proinflammatory cytokines or angiostatic agents. T cells emigrating into the CNS during EAE encountered two biochemically distinct basement membranes, the endothelial (containing laminins 8 and 10) and the parenchymal (containing laminins 1 and 2) basement membranes. However, inflammatory cuffs occurred exclusively around endothelial basement membranes containing laminin 8, whereas in the presence of laminin 10 no infiltration was detectable. In vitro assays using encephalitogenic T cell lines revealed adhesion to laminins 8 and 10, whereas binding to laminins 1 and 2 could not be induced. Downregulation of integrin α6 on cerebral endothelium at sites of T cell infiltration, plus a high turnover of laminin 8 at these sites, suggested two possible roles for laminin 8 in the endothelial basement membrane: one at the level of the endothelial cells resulting in reduced adhesion and, thereby, increased penetrability of the monolayer and secondly at the level of the T cells providing direct signals to the transmigrating cells.
Publisher: Oxford University Press (OUP)
Date: 05-1997
DOI: 10.1093/HMG/6.5.747
Abstract: Congenital muscular dystrophy (CMD) is a group of clinically and genetically heterogeneous disorders inherited in an autosomal recessive mode. The alpha2-chain of laminin-2 (previously called merosin) has been shown by immunohistochemical and genetic analyses to be implicated in the pathogenesis of the 'classic' form of CMD. In the 'merosin-deficient' subgroup, which represents about half of the cases, more definite evidence of the involvement of the laminin alpha2-chain has recently been reported with the identification of mutations in the gene encoding the alpha2-chain of laminin 2 (LAMA2) in CMD patients. Here we report on two siblings from a consanguineous family expressing an internally deleted laminin alpha2-chain as a result of a splice site mutation in the LAMA2 gene which causes the splicing of exon 25. The predicted protein lacks 63 amino acids in domain IVa which forms a globular structure on the short arm of the alpha2-chain. Interestingly, these patients appear mildly affected compared to others who completely lack this protein. This situation presents a striking analogy with Becker muscular dystrophy, where in-frame deletions in the dystrophin gene result in the expression of a semi-functional protein and lead to a mild phenotype.
Publisher: Elsevier BV
Date: 08-2003
DOI: 10.1016/S0012-1606(03)00254-9
Abstract: Laminins (comprised of alpha, beta, and gamma chains) are heterotrimeric glycoproteins integral to all basement membranes. The function of the laminin alpha5 chain in the developing intestine was defined by analysing laminin alpha5(-/-) mutants and by grafting experiments. We show that laminin alpha5 plays a major role in smooth muscle organisation and differentiation, as excessive folding of intestinal loops and delay in the expression of specific markers are observed in laminin alpha5(-/-) mice. In the subepithelial basement membrane, loss of alpha5 expression was paralleled by ectopic or accelerated deposition of laminin alpha2 and alpha4 chains this may explain why no obvious defects were observed in the villous form and enterocytic differentiation. This compensation process is attributable to mesenchyme-derived molecules as assessed by chick/mouse alpha5(-/-) grafted associations. Lack of the laminin alpha5 chain was accompanied by a decrease in epithelial alpha3beta1 integrin receptor expression adjacent to the epithelial basement membrane and of Lutheran blood group glycoprotein in the smooth muscle cells, indicating that these receptors are likely mediating interactions with laminin alpha5-containing molecules. Taken together, the data indicate that the laminin alpha5 chain is essential for normal development of the intestinal smooth muscle and point to possible mesenchyme-derived compensation to promote normal intestinal morphogenesis when laminin alpha5 is absent.
Publisher: Elsevier BV
Date: 05-2010
DOI: 10.1016/J.IMMUNI.2010.04.017
Abstract: Chemokines orchestrate immune cell trafficking by eliciting either directed or random migration and by activating integrins in order to induce cell adhesion. Analyzing dendritic cell (DC) migration, we showed that these distinct cellular responses depended on the mode of chemokine presentation within tissues. The surface-immobilized form of the chemokine CCL21, the heparan sulfate-anchoring ligand of the CC-chemokine receptor 7 (CCR7), caused random movement of DCs that was confined to the chemokine-presenting surface because it triggered integrin-mediated adhesion. Upon direct contact with CCL21, DCs truncated the anchoring residues of CCL21, thereby releasing it from the solid phase. Soluble CCL21 functionally resembles the second CCR7 ligand, CCL19, which lacks anchoring residues and forms soluble gradients. Both soluble CCR7 ligands triggered chemotactic movement, but not surface adhesion. Adhesive random migration and directional steering cooperate to produce dynamic but spatially restricted locomotion patterns closely resembling the cellular dynamics observed in secondary lymphoid organs.
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 11-2007
DOI: 10.1167/IOVS.07-0654
Publisher: Springer Science and Business Media LLC
Date: 22-06-2018
DOI: 10.1038/S41598-018-27879-Z
Abstract: Time-lapse MRI was implemented for dynamic non-invasive cell tracking of in idual slowly moving intravascular immune cells. Repetitive MRI acquisition enabled dynamic observation of iron oxide nanoparticle (ION) labelled cells. Simulations of MRI contrast indicated that only cells moving slower than 1 µm/s were detectable. Time-lapse MRI of the brain was performed after either IONs or ION-labelled monocytes were injected intravenously into naïve and experimental autoimmune encephalomyelitis (EAE) bearing mice at a presymptomatic or symptomatic stage. EAE mice showed a reduced number of slow moving, i.e. patrolling cells before and after onset of symptoms as compared to naïve controls. This observation is consistent with the notion of altered cell dynamics, i.e. higher velocities of immune cells rolling along the endothelium in the inflamed condition. Thus, time-lapse MRI enables for assessing immune cell dynamics non-invasively in deep tissue and may serve as a tool for detection or monitoring of an inflammatory response.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 09-11-2016
DOI: 10.1126/SCITRANSLMED.AAF8020
Abstract: A method to visualize MMPs reveals penetration of the blood-brain barrier by leukocytes early in multiple sclerosis.
Publisher: Society for Neuroscience
Date: 07-01-2020
DOI: 10.1523/JNEUROSCI.1266-19.2019
Abstract: Leukocyte entry into the central nervous system (CNS) is essential for immune surveillance but is also the basis for the development of pathologic inflammatory conditions within the CNS, such as multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). The actin-binding protein, cortactin, in endothelial cells is an important player in regulating the interaction of immune cells with the vascular endothelium. Cortactin has been shown to control the integrity of the endothelial barrier and to support neutrophil transendothelial migration in vitro and in vivo in the skin. Here we use cortactin gene-inactivated male and female mice to study the role of this protein in EAE. Inducing EAE by immunization with a myelin oligodendrocyte glycoprotein peptide (MOG 35–55 ) revealed an ameliorated disease course in cortactin gene-deficient female mice compared with WT mice. However, proliferation capacity and expression of IL-17A and IFNγ by cortactin-deficient and WT splenocytes did not differ, suggesting that the lack of cortactin does not affect induction of the immune response. Rather, cortactin deficiency caused decreased vascular permeability and reduced leukocyte infiltration into the brains and spinal cords of EAE mice. Accordingly, cortactin gene-deficient mice had smaller numbers of proinflammatory cuffs, less extensive demyelination, and reduced expression levels of proinflammatory cytokines within the neural tissue compared with WT littermates. Thus, cortactin contributes to the development of neural inflammation by supporting leukocyte transmigration through the blood–brain barrier and, therefore, represents a potential candidate for targeting CNS autoimmunity. SIGNIFICANCE STATEMENT Multiple sclerosis is an autoimmune neuroinflammatory disorder, based on the entry of inflammatory leukocytes into the CNS where these cells cause demyelination and neurodegeneration. Here, we use a mouse model for multiple sclerosis, experimental autoimmune encephalomyelitis, and show that gene inactivation of cortactin, an actin binding protein that modulates actin dynamics and branching, protects against neuroinflammation in experimental autoimmune encephalomyelitis. Leukocyte infiltration into the CNS was inhibited in cortactin-deficient mice, and lack of cortactin in cultured primary brain endothelial cells inhibited leukocyte transmigration. Expression levels of proinflammatory cytokines in the CNS and induction of vascular permeability were reduced. We conclude that cortactin represents a novel potential target for the treatment of multiple sclerosis.
Publisher: Wiley
Date: 07-1998
DOI: 10.1002/(SICI)1097-0177(199807)212:3<394::AID-AJA7>3.0.CO;2-C
Abstract: Vitamin D-dependent rickets type 1A (VDDR1A) is a rare autosomal recessive disorder caused by deficiency of the Twelve children from southern China with VDDR1A were enrolled in this study. Their clinical, radiological, biochemical, and molecular findings were analyzed retrospectively. The rickets severity score (RSS), biochemical parameters, and height standard deviation score (HtSDS) were used to evaluate clinical outcomes. Six males and six females were included in this VDDR1A cohort. The age of onset was from 6 months to 1.8 years, and the age at diagnosis was 2.1 ± 0.8 years. The most common clinical symptoms at diagnosis were delayed walking (10/12) and severe growth retardation (9/12). HtSDS at diagnosis was negatively associated with age ( Our study extends the mutational spectrum of VDDR1A and finds a hotspot variant of the
Publisher: SAGE Publications
Date: 12-2001
DOI: 10.1177/00220345010800121401
Abstract: It is not known whether epithelial differentiation patterns are reflected in the composition of gingival basement membranes (BMs). We have investigated the expression of laminin isoforms and associated BM components in the murine dento-epithelial junction by using immunofluorescence microscopy. Our results show that chains of laminins 5/6/7/10/11 are expressed in the BM of outer gingival epithelium. The external BM between junctional epithelium (JE) and connective tissue differs from gingival BM by lacking laminin-7 and -11 chains. The internal basal lamina (IBL) between JE and tooth contains only laminin-5. Collagen chains α1,2(IV) and nidogen-1 are present in other BMs except the IBL. The dento-epithelial junction thus has a unique BM composition, suggesting that epithelial cells are able to secrete two extracellular matrices in a polarized manner. The exclusive expression of the non-self-polymerizing laminin-5 indicates that the IBL is not a BM by definition, but rather a simple extracellular matrix lacking network structure.
Publisher: Elsevier BV
Date: 1999
Abstract: Laminins are extracellular matrix glycoproteins that are involved in various cellular functions, including adhesion, proliferation, and differentiation. In this study, we examine the expression patterns and the cellular origins of the laminin alpha2, alpha4, and alpha5 chains in the developing mouse intestine and in in vitro mouse/chick or chick/mouse interspecies hybrid intestines. In situ hybridization and Northern blot analysis revealed that mRNA levels for all three laminin alpha chains are highest in the fetal intestine undergoing intense morphogenetic movements. Laminin alpha4 mRNA and polypeptide are associated with mesenchyme-derived cell populations such as endothelium and smooth muscle. In contrast, laminin alpha2 and alpha5 chains participate in the structural organization of the subepithelial basement membrane and, in the mature intestine, show a complementary pattern of expression. All three laminin alpha chains occur in the smooth muscle basement membrane, with a differential expression of laminin alpha5 chain in the circular and longitudinal smooth muscle layers. The cellular origin of laminin alpha2 and alpha5 chains found in the subepithelial cell basement membrane was studied by immunocytochemical analysis of mouse/chick or chick/mouse interspecies hybrid intestines at various stages of development using mouse-specific antibodies. Laminin alpha2 was found to be deposited into the basement membrane exclusively by mesenchymal cells, while the laminin alpha5 chain was deposited by both epithelial and mesenchymal cells in an apparently developmentally regulated pattern. We conclude that (1) multiple laminin alpha chains are expressed in the intestine, implying specific roles for in idual laminin isoforms during intestinal development, and (2) reciprocal epithelial/mesenchymal interactions are essential for the formation of a structured subepithelial basement membrane.
Publisher: Elsevier BV
Date: 2017
Publisher: Rockefeller University Press
Date: 20-10-1997
Abstract: Laminins, the main components of basement membranes, are heterotrimers consisting of α, β, and γ polypeptide chains linked together by disulfide bonds. Laminins-1 and -2 are both composed of β1 and γ1 chains and differ from each other on their α chain, which is α1 and α2 for laminin-1 and -2, respectively. The present study shows that whereas laminins-1 and -2 are synthesized in the mouse developing lung and in epithelial–mesenchymal cocultures derived from it, epithelial and mesenchymal monocultures lose their ability to synthesize the laminin α1 chain. Synthesis of laminin α1 chain however returns upon re-establishment of epithelial–mesenchymal contact. Cell–cell contact is critical, since laminin α1 chain is not detected in monocultures exposed to coculture-conditioned medium or in epithelial–mesenchymal cocultures in which heterotypic cell–cell contact is prevented by an interposing filter. Immunohistochemical studies on cocultures treated with brefeldin A, an inhibitor of protein secretion, indicated both epithelial and mesenchymal cells synthesize laminin α1 chain upon heterotypic cell– cell contact. In a set of functional studies, embryonic lung explants were cultured in the presence of monoclonal antibodies to laminin α1, α2, and β/γ chains. Lung explants exposed to monoclonal antibodies to laminin α1 chain exhibited alterations in peribronchial cell shape and decreased smooth muscle development, as indicated by low levels of smooth muscle α actin and desmin. Taken together, our studies suggest that laminin α1 chain synthesis is regulated by epithelial–mesenchymal interaction and may play a role in airway smooth muscle development.
Publisher: Wiley
Date: 06-2008
DOI: 10.1111/J.1527-3466.2008.00046.X
Abstract: The efficacy of a new torasemide prolonged release (PR) formulation to torasemide immediate release (IR) was compared in a randomized noninferiority double-blind trial. Patients with newly diagnosed mild-to-moderate hypertension or unresponsive or poor tolerability to previous antihypertensive monotherapy received 5 mg/day of torasemide-PR (n = 219) or torasemide-IR (n = 223) for 12 weeks (uptitration to 10 mg/day if no response at 4 or 8 weeks). Mean diastolic blood pressure (DBP) reduction in the torasemide-PR group (11.6 +/- 7.1 mmHg, 95% confidence interval [CI] 10.6-12.5) versus torasemide-IR (11.3 +/- 7.5 mmHg, 95% CI 10.2-12.3) met the noninferiority criterion of a nonsided 97.5% CI lower than the preestablished margin of 2 mmHg. A significantly higher percentage of patients in the torasemide-PR group achieved adequate BP control after 8 and 12 weeks. Ambulatory 24-h BP monitoring (ABPM) measurements in a subset of 100 patients showed greater daytime SBP reductions in the torasemide-PR group (128.4 +/- 9.9 mmHg vs. 133.5 +/- 10.4 mmHg, P < 0.05). Safety and tolerability of both formulations were similar.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-1998
DOI: 10.1212/WNL.51.1.94
Abstract: To characterize the expression of distinct fragments of laminin alpha2 chain in patients with partial laminin alpha2 chain deficiency and variable clinical severity. Deficiency of laminin alpha2 chain caused by mutations of the LAMA2 gene on chromosome 6q2 account for approximately 50% of cases of congenital muscular dystrophy (CMD) in white patients. The complete absence of laminin alpha2 is usually associated with a severe phenotype affecting skeletal muscle and the peripheral and central nervous systems. Quantitative assessment of immunofluorescence to study the expression of C- and N-terminal portions of laminin alpha2 chain in five patients with partial laminin alpha2 chain deficiency and variable phenotype. All five patients showed abnormal T2 signal on brain MRI. Immunohistochemistry of muscle specimens showed preserved or minimally reduced expression of the C-terminal region of the laminin alpha2 chain (67 to 74%), but a marked reduction of the N-terminal region in four patients (13 to 19%). One patient with a mild phenotype had a partial reduction (45%) of the C-terminal and the N-terminal (51%) portions of the laminin alpha2 chain. Two patients were unable to walk or sit, although the C-terminal portion of the laminin alpha2 chain was expressed at significant levels (67 to 74%). In contrast, two patients with a similar expression of the C-terminus (67 to 70%) had a milder phenotype and became ambulatory. It was impossible to predict the phenotypes in these four patients with a strong expression of the C-terminus and with low levels of the N-terminus based on the amount of protein expressed. In addition, the laminin beta2 chain was moderately reduced (54 to 75%) in all patients with laminin alpha2 chain deficiency. A strong correlation between the amount of the C-terminus but not for the N-terminus and laminin beta2 reduction could be observed. N-terminal antibodies to the laminin alpha2 chain provide a more precise immunohistochemical detection of partially laminin alpha2 chain-deficient CMD. The secondary reduction of laminin beta2 chain may better define laminin alpha2 chain-deficient CMD. More data are needed to predict which portions of C-terminus and midrod region of the laminin alpha2 chain result in a semifunctional protein and a milder phenotype.
Publisher: EMBO
Date: 07-10-2011
Publisher: Informa UK Limited
Date: 1995
Publisher: American Chemical Society (ACS)
Date: 02-10-2018
DOI: 10.1021/ACS.BIOCONJCHEM.8B00618
Abstract: Matrix metalloproteinases (MMPs) are emerging as pivotal fine-tuners of cell function in tissue homeostasis and in various pathologies, in particular inflammation. In vivo monitoring of the activity of specific MMPs, therefore, provides high potential for assessing disease progression and tissue function, and manipulation of MMP activity in tissues and whole organisms may further provide a mode of controlling pathological processes. We describe here the synthesis of novel fluorinated and nonfluorinated analogues of a secondary sulfonamide-based lead structure, compound 2, and test their efficacy as in vivo inhibitors and tracers of the gelatinases, MMP-2 and MMP-9. Using a murine neuroinflammatory model, we show that compound 2 is a highly effective in vivo inhibitor of both MMP-2 and MMP-9 activity with little or no adverse effects even after long-term daily oral administration. A fluorescein-labeled derivative compound 17 shows direct binding to activated gelatinases surrounding inflammatory cuffs in the neuroinflammation model and to pancreatic β-cells in the islets of Langerhans, colocalizing with MMP-2 and MMP-9 activity as detected using in situ zymography techniques. These results demonstrate that compound 2 derivatives have potential as in vivo imaging tools and for future development for specific MMP-2 versus MMP-9 probes. Our chemical modifications mainly target the residues directed toward the S1' and S2' pockets and, thereby, provide new information on the structure-activity relationships of this inhibitor type.
Publisher: Elsevier BV
Date: 06-1996
Abstract: An infrared thermometer was first used to assess drought and heat tolerance in plant breeding more than 40 years ago. Soon afterward, this method became widely used throughout the world. However, Russia has not yet applied the described method for evaluating stress tolerance. This paper presents an overview of using infrared thermometry in plant breeding. Taking wheat as an ex le, it shows major advantages and disadvantages of canopy temperature depression (CTD) values measured by the infrared thermometer. The paper also demonstrates that genotypes with higher CTD values, and therefore with a lower canopy temperature, use more available soil moisture under drought stress to cool the canopy by transpiration. It refers to CTD as an integrative trait that reflects an overall plant water status. Its coefficient of variation lies in the interval of 10 to 43 %. A large number of publications illustrate a close relation between CTD values and yield and indicate a high heritability of the former. Meanwhile, the same works show that yield has a higher heritability. Moreover, some researchers doubt that CTD should be used in applied wheat breeding as there are many factors that influence it. CTD has a high correlation with other traits that reflect plant water status or their adaptation to drought or heat stress. Quantitative trait loci (QTLs) associated with CTD are localized in all chromosomes, except for 3D. These QTLs often explain a small part of phenotypic variance (10-20 %, more likely less than 10 %), which complicates the pyramiding of canopy temperature genes through marker-assisted selection. The paper concludes that the evaluation of CTD appears to be a reliable, relatively simple, labor-saving, objective, and non-invasive method that sets it apart from other methods as well as shows the best results under terminal drought and heat stress conditions.
Publisher: Elsevier BV
Date: 09-1997
Abstract: We have previously shown that mouse and bovine endothelial cells express a novel 400-kDa laminin alpha chain complexed to beta1 and gamma1 laminin chains. We describe here purification of this laminin isoform from the conditioned medium of a mouse peripheral lymph node endothelial cell line, SVEC. The laminin alpha chain was isolated from the laminin complex, subjected to Edman digestion, and the amino acid sequences of the resulting peptides were determined. Amino acid sequence revealed 100% identity to the predicted amino acid sequence of the recently reported laminin alpha5 gene. A monoclonal antibody to the laminin alpha5 chain was raised (4G6), allowing investigation of its distribution in embryonic, newborn, and mature mouse tissues. The laminin alpha5 chain was expressed mainly by epithelial, endothelial, and myogenic cells: In both embryonic and mature tissues the laminin alpha5 chain was strongly expressed by epithelial cells, the bronchi of the lungs and the developing kidney tubules being the sites of strongest expression. However, laminin alpha5 was not associated with early stages of epithelial cell development, but rather with epithelial cell maturation. Widespread expression of laminin alpha5 in endothelial cells was apparent only in tissues of mature mice, its appearance correlating approximately with sexual maturity. During embryogenesis and in newborn tissues, laminin alpha5 occurred in basement membranes of larger blood vessels only, excluding a role in angiogenic processes. Smooth muscle and skeletal muscle cells were the only other cell types which showed considerable laminin alpha5 expression, with skeletal muscle exhibiting a developmentally regulated pattern of expression: The laminin alpha5 chain occurred in skeletal muscle fiber basement membranes early in embryogenesis (E13-E15) but decreased with development, remaining strongly expressed only at the neuromuscular junction. The data show that laminin alpha5 expression is associated with epithelial and endothelial cell maturation, implicating a role for this laminin chain in the maintenance of differentiated epithelial and endothelial cell phenotype.
Publisher: eLife Sciences Publications, Ltd
Date: 13-06-2022
Publisher: S. Karger AG
Date: 2004
DOI: 10.1159/000080348
Publisher: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.CEB.2015.06.006
Abstract: The extracellular matrix (ECM) comes in different structural forms and biochemical compositions, which determine both its biophysical properties and its ability to convey specific signals to immune cells encountering or navigating through it. Traditionally, the role of the in idual ECM molecules on cell migration has been investigated independent of considerations such as the tension/mechanical strength constituted by the ECM. However, more recently, this aspect has attracted considerable attention and data suggest that rigidity and molecular signals derived from the ECM define the mode of cell migration. We here review the different types of ECM encountered by migrating immune cells in vivo, as well as current information on how both molecular components of the ECM and their supramolecular structure can impact on modes of immune cell migration.
Publisher: Springer Science and Business Media LLC
Date: 30-11-2022
DOI: 10.1038/S41467-022-35166-9
Abstract: Perivascular macrophages (pvMs) are associated with cerebral vasculature and mediate brain drainage and immune regulation. Here, using reporter mouse models, whole brain and section immunofluorescence, flow cytometry, and single cell RNA sequencing, besides the Lyve1 + F4/80 + CD206 + CX3CR1 + pvMs, we identify a CX3CR1 – pvM population that shares phagocytic functions and location. Furthermore, the brain parenchyma vasculature mostly hosts Lyve1 + MHCII – pvMs with low to intermediate CD45 expression. Using the double Cx3cr1 GFP x Cx3cr1-Cre Rosa tdT reporter mice for finer mapping of the lineages, we establish that CD45 low CX3CR1 – pvMs are derived from CX3CR1 + precursors and require PU.1 during their ontogeny. In parallel, results from the Cxcr4-CreErt2 Rosa26 tdT lineage tracing model support a bone marrow-independent replenishment of all Lyve1 + pvMs in the adult mouse brain. Lastly, flow cytometry and 3D immunofluorescence analysis uncover increased percentage of pvMs following photothrombotic induced stroke. Our results thus show that the parenchymal pvM population is more heterogenous than previously described, and includes a CD45 low and CX3CR1 – pvM population.
Publisher: Wiley
Date: 12-1997
DOI: 10.1002/(SICI)1097-0177(199712)210:4<446::AID-AJA8>3.0.CO;2-G
Abstract: Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can increase the value of seagrass beds as habitat for nekton via added food resources and structural complexity. But, as algal biomass increases, it can also decrease light availability, inhibit faunal movements, smother benthic communities, and contribute to hypoxia, all of which can reduce nekton abundance. We quantified the abundance and distribution of drift macroalgae within seagrass meadows dominated by turtle grass
Publisher: Proceedings of the National Academy of Sciences
Date: 11-07-2013
Abstract: We describe a unique extracellular matrix (ECM) niche in the spleen, the marginal zone (MZ), that supports a specialized population of MZ B lymphocytes that respond rapidly to blood-borne antigens and are therefore crucial for the first line of immune defense. We show, for the first time, that both the novel 3D structure and the biochemical composition of the ECM impacts on B-cell fate and survival. Similar pericellular ECM networks occur in thymus, bone marrow, and lymph node hence, our data are likely to have broader ramifications to the fate and survival of other immune cells.
Publisher: Wiley
Date: 09-07-1993
Abstract: A new cell line from a sporadic Wilms' tumor was established and extensively characterized. In nude mice, the tumor cells rapidly formed tumors which, in histological characteristics and extracellular-matrix (ECM) composition resembled sarcomatoid Wilms' tumor. The tumor cells produced B chains of laminin, but no A chain, and laminin was deposited into the ECM in a punctate pattern typical of sarcomatoid tumors. Strong expression of tenascin was detected within the stromal ECM of the tumors. Species-specific antibodies reacting either with human or with mouse tenascin showed that tenascin was exclusively derived from mouse host cells. The human Wilms' cell line thus induced a strong stromal response with increased deposition of tenascin. The cell line may be useful for studying the behavior of sarcomatoid Wilms' tumor cells and for identifying factors that stimulate synthesis of tenascin.
Publisher: Elsevier BV
Date: 07-2009
DOI: 10.1038/JID.2008.424
Abstract: Collagen XVII (BP180) and its shed ectodomain represent major autoantigens in dermatoses of the pemphigoid group. The 120 kDa ectodomain is constitutively shed from the cell surface by disintegrin-metalloproteinases (ADAMs). Part of it is further processed to a 97 kDa fragment (LABD97), an autoantigen in linear IgA dermatosis (LAD), but the responsible proteinases remain elusive. In this study, we identified the 120 and the 97 kDa ectodomain in blister fluids of bullous pemphigoid patients using new mAbs. As blister fluids contain significant plasmin-like serine protease activity, HaCaT keratinocytes or purified 120 kDa ectodomain were incubated with several human serine proteases. In vitro, only plasmin generated a stable 97 kDa fragment that was also targeted by LAD sera. Characterization of the plasmin-derived 97 kDa fragment with domain-specific collagen XVII antibodies, heparin binding and N-glycosylation studies indicates that the N-terminus is located approximately at AA 515 and the C-terminus N-terminally from AA 1,421. Interestingly, plasmin-derived LABD97 was also generated in the presence of ADAM inhibitors and remained stable over more than 12 hours incubation at 37 degrees C, indicating that this disease relevant collagen XVII fragment can also arise in an ADAM-independent manner through direct action by plasmin.
Publisher: Wiley
Date: 11-1997
DOI: 10.1002/(SICI)1097-0177(199711)210:3<206::AID-AJA2>3.0.CO;2-K
Abstract: Investigating how people respond to and view AI-created artworks is becoming increasingly crucial as the technology's current application spreads due to its affordability and accessibility. This study examined how AI art alters people's evaluation, purchase intention, and collection intention toward Chinese-style and Western-style paintings, and whether art expertise plays a role. Study 1 recruited participants without professional art experience (non-experts) and found that those who made the paintings would not change their liking rating, purchase intention, and collection intention. In addition, they showed ingroup preference, favoring Chinese-style relative to Western-style paintings, in line with previous evidence on cultural preference in empirical aesthetics. Study 2 further investigated the modulation effect of art expertise. Art experts evaluated less favorably (less liking, lower purchase, and collection intentions) AI-generated paintings relative to artist-made paintings, while non-experts showed no preference. There was also an interaction effect between the author and the art expertise and interaction between the painting style and the art expertise. Collectively, the findings in this study showed that who made the art matters for experts and that the painting style affects aesthetic evaluation and ultimate reception of it. These results would also provide implications for AI-art practitioners.
Publisher: Rockefeller University Press
Date: 07-05-2020
DOI: 10.1084/JEM.20191339
Abstract: The endothelial cell basement membrane (BM) is a barrier to migrating leukocytes and a rich source of signaling molecules that can influence extravasating cells. Using mice lacking the major endothelial BM components, laminin 411 or 511, in murine experimental autoimmune encephalomyelitis (EAE), we show here that loss of endothelial laminin 511 results in enhanced disease severity due to increased T cell infiltration and altered polarization and pathogenicity of infiltrating T cells. In vitro adhesion and migration assays reveal higher binding to laminin 511 than laminin 411 but faster migration across laminin 411. In vivo and in vitro analyses suggest that integrin α6β1- and αvβ1-mediated binding to laminin 511–high sites not only holds T cells at such sites but also limits their differentiation to pathogenic Th17 cells. This highlights the importance of the interface between the endothelial monolayer and the underlying BM for modulation of immune cell phenotype.
Publisher: Elsevier BV
Date: 1999
Abstract: The dy/dy mouse is an animal model for human merosin-negative congenital muscular dystrophy (CMD), which has been reported to have reduced or no expression of the basement membrane protein laminin alpha2. We here investigate various myogenic and nonmyogenic tissues of mature dy/dy and control 129ReJ mice histologically and for laminin alpha2 expression. In addition, expression patterns of laminin alpha1, alpha2, alpha4, and alpha5 chains, the interstitial proteins fibronectin and tenascin-C, and the adhesion molecules VCAM-1, ICAM-1, and alpha4 integrin were characterized in skeletal muscle of 1- and 7-day and mature (>6 weeks old) dy/dy and control 129ReJ mice. The laminin alpha2 chain remained detectable in myogenic tissues of dy/dy mice by immunofluorescence using two different monoclonal antibodies and by Northern blot analysis. However, laminin alpha2 expression was significantly reduced or not detectable in nonmyogenic tissues of dy/dy mice, including skin, lung, kidney, brain, thymus, and eye. Focal lesions were observed in mature skeletal muscle only, characterized by necrotic tissue, isolated VCAM-1- and ICAM-1-positive cells indicative of inflammatory processes, and regenerating muscle fibers surrounded by intense tenascin-C and fibronectin expression. In contrast to studies on human CMD muscle, laminin alpha1 was not detectable in either dy/dy or control skeletal muscle using immunofluorescence or Northern blot analysis. Immunofluorescence localized laminin alpha4 to basement membranes of blood vessels, the endoneurium of the intramuscular nerves, and the neuromuscular junction in skeletal muscle of 1- and 7-day-old dy/dy and control mice. In mature muscle, laminin alpha4 expression shifted to the perineurium of intramuscular nerves in both dy/dy and control mice. Furthermore, strong upregulation of laminin alpha4 in the basement membranes of blood vessels, the perineurium of intramuscular nerves, and of isolated regenerating muscle fibers in the dy/dy mice was apparent. Investigation of 1-day-old animals revealed expression of laminin alpha5 in skeletal muscle fiber basement membranes of dy/dy but not control animals. This difference between dy/dy and control animals was no longer apparent at 7 days after birth, indicating a temporary shift in expression pattern of laminin alpha5 in dy/dy animals. Analysis of the extracellular matrix components of 1- and 7-day-old dy/dy and control skeletal muscle revealed an early onset of the dystrophy, even before histopathological features of the disease were evident. Our data confirm the absence of laminin alpha1 chain in myogenic tissues of both dy/dy and control mice and suggest compensation for reduced laminin alpha2 in dy/dy skeletal muscle by laminin alpha4 and, in early development, also laminin alpha5. These results have significant ramifications in the diagnosis of human merosin-negative CMD.
Publisher: SAGE Publications
Date: 07-2015
Abstract: Stroke is the most common cause of death and disability from neurologic disease in humans. Activation of microglia and matrix metalloproteinases (MMPs) is involved in positively and negatively affecting stroke outcome. Novel, noninvasive, multimodal imaging methods visualizing microglial and MMP alterations were employed. The spatio-temporal dynamics of these parameters were studied in relation to blood flow changes. Micro positron emission tomography (μPET) using [ 18 F]BR-351 showed MMP activity within the first days after transient middle cerebral artery occlusion (tMCAo), followed by increased [ 18 F]DPA-714 uptake as a marker for microglia activation with a maximum at 14 days after tMCAo. The inflammatory response was spatially located in the infarct core and in adjacent (penumbral) tissue. For the first time, multimodal imaging based on PET, single photon emission computed tomography, and magnetic resonance imaging revealed insight into the spatio-temporal distribution of critical parameters of poststroke inflammation. This allows further evaluation of novel treatment paradigms targeting the postischemic inflammation.
Publisher: Springer Science and Business Media LLC
Date: 14-09-2014
DOI: 10.1038/NCB3036
Publisher: Rockefeller University Press
Date: 15-04-1995
Abstract: Branching epithelial morphogenesis requires interactions between the surrounding mesenchyme and the epithelium, as well as interactions between basement membrane components and the epithelium. Embryonic submandibular gland was used to study the roles of two mesenchymal proteins, epimorphin and tenascin-C, as well as the epithelial protein laminin-1 and one of its integrin receptors on branching morphogenesis. Laminin-1 is a heterotrimer composed of an alpha 1 chain and two smaller chains (beta 1 and gamma 1). Immunofluorescence revealed a transient expression of laminin alpha 1 chain in the epithelial basement membrane during early stages of branching morphogenesis. Other laminin-1 chains and alpha 6, beta 1, and beta 4 integrin subunits seemed to be expressed constitutively. Expression of epimorphin, but not tenascin-C, was seen in the mesenchyme during early developmental stages, but a mAb against epimorphin did not perturb branching morphogenesis of this early epithelium. In contrast, inhibition of branching morphogenesis was seen with a mAb against the carboxy terminus of laminin alpha 1 chain, the E3 domain. An inhibition of branching was also seen with a mAb against the integrin alpha 6 subunit. The antibodies against laminin alpha 1 chain and integrin alpha 6 subunit perturbed development in distinct fashions. Whereas treatment with the anti-E3 resulted in discontinuities of the basement membrane at the tips of the branching epithelium, treatment with the mAb against alpha 6 integrin subunit seemed to leave the basement membrane intact. We suggest that the laminin E3 domain is involved in basement membrane formation, whereas alpha 6 beta 1 integrin binding to laminin-1 may elicit differentiation signals to the epithelial cells.
Publisher: Elsevier BV
Date: 02-2015
DOI: 10.1016/J.CELREP.2015.01.037
Abstract: Although chemokines are sufficient for chemotaxis of various cells, increasing evidence exists for their fine-tuning by selective proteolytic processing. Using a model of immune cell chemotaxis into the CNS (experimental autoimmune encephalomyelitis [EAE]) that permits precise localization of immigrating leukocytes at the blood-brain barrier, we show that, whereas chemokines are required for leukocyte migration into the CNS, additional MMP-2/9 activities specifically at the border of the CNS parenchyma strongly enhance this transmigration process. Cytokines derived from infiltrating leukocytes regulate MMP-2/9 activity at the parenchymal border, which in turn promotes astrocyte secretion of chemokines and differentially modulates the activity of different chemokines at the CNS border, thereby promoting leukocyte migration out of the cuff. Hence, cytokines, chemokines, and cytokine-induced MMP-2/9 activity specifically at the inflammatory border collectively act to accelerate leukocyte chemotaxis across the parenchymal border.
Publisher: The American Association of Immunologists
Date: 15-04-2005
DOI: 10.4049/JIMMUNOL.174.8.4821
Abstract: The NOD mouse is an important experimental model for human type 1 diabetes. T cells are central to NOD pathogenesis, and their function in the autoimmune process of diabetes has been well studied. In contrast, although recognized as important players in disease induction, the role of B cells is not clearly understood. In this study we characterize different subpopulations of B cells and demonstrate that marginal zone (MZ) B cells are expanded 2- to 3-fold in NOD mice compared with nondiabetic C57BL/6 (B6) mice. The NOD MZ B cells displayed a normal surface marker profile and localized to the MZ region in the NOD spleen. Moreover, the MZ B cell population developed early during the ontogeny of NOD mice. By 3 wk of age, around the time when autoreactive T cells are first activated, a significant MZ B cell population of adult phenotype was found in NOD, but not B6, mice. Using an F2(B6 × NOD) cross in a genome-wide scan, we map the control of this trait to a region on chromosome 4 (logarithm of odds score, 4.4) which includes the Idd11 and Idd9 diabetes susceptibility loci, supporting the hypothesis that this B cell trait is related to the development of diabetes in the NOD mouse.
Publisher: Springer Science and Business Media LLC
Date: 23-12-2010
Publisher: Springer Science and Business Media LLC
Date: 1989
DOI: 10.1007/BF02624412
Publisher: The Company of Biologists
Date: 12-1995
Abstract: The expression of laminin-1 (previously EHS laminin) and laminin-2 (previously merosin) isoforms by myogenic cells was examined in vitro and in vivo. No laminin α2 chain-specific antibodies react with mouse tissues, so rat mono-clonal antibodies were raised against the mouse laminin α2 chain: their characterization is described here. Myoblasts and myotubes from myogenic cell lines and primary myogenic cultures express laminin β1 and γ1 chains and form a complex with a 380 kDa α chain identified as laminin α2 by immunofluorescence, immunoprecipitation and PCR. PCR from C2C12 myoblasts and myotubes for the laminin α2 chain gene (LamA2) provided cDNA sequences which were used to investigate the in vivo expression of mouse LamA2 mRNA in embryonic tissues by in situ hybridization. Comparisons were made with specific probes for the laminin α1 chain gene (LamA1). LamA2 but not LamA1 mRNA was expressed in myogenic tissues of 14-and 17-day-old mouse embryos, while the laminin α2 polypeptide was localized in adjacent basement membranes in the muscle fibres. In situ hybridization also revealed strong expression of the LamA2 mRNA in the dermis, indicating that laminin α2 is expressed other than by myogenic cells in vivo. Immunofluorescence studies localized laminin α2 in basement membranes of basal ker-atinocytes and the epithelial cells of hair follicles, providing new insight into basement membrane assembly during embryogenesis. In vitro cell attachment assays revealed that C2C12 and primary myoblasts adhere to laminin-1 and -2 isoforms in a similar manner except that myoblast spreading was sig-nificantly faster on laminin-2. Taken together, the data suggest that laminins 1 and 2 play distinct roles in myo-genesis.
Publisher: Society for Neuroscience
Date: 12-03-2018
DOI: 10.1523/JNEUROSCI.3064-17.2018
Abstract: Fractones are extracellular matrix structures in the neural stem cell niche of the subventricular zone (SVZ), where they appear as round deposits named bulbs or thin branching lines called stems. Their cellular origin and what determines their localization at this site is poorly studied, and it remains unclear whether they influence neural stem and progenitor cell formation, proliferation, and/or maintenance. To address these questions, we analyzed whole-mount preparations of the lateral ventricle of male and female mice by confocal microscopy using different extracellular matrix and cell markers. We found that bulbs are rarely connected to stems and that they contain laminin α5 and α2 chains, respectively. Fractone bulbs were profusely distributed throughout the SVZ and appeared associated with the center of pinwheels, a critical site for adult neurogenesis. We demonstrate that bulbs appear at the apical membrane of ependymal cells at the end of the first week after birth. The use of transgenic mice lacking laminin α5 gene expression ( Lama5 ) in endothelium and in FoxJ1-expressing ependymal cells revealed ependymal cells as the source of laminin α5-containing fractone bulbs. Deletion of laminin α5 from ependymal cells correlated with a 60% increase in cell proliferation, as determined by phospho-histone H3 staining, and with a selective reduction in the number of slow- iding cells. These results indicate that fractones are a key component of the SVZ and suggest that laminin α5 modulates the physiology of the neural stem cell niche. SIGNIFICANCE STATEMENT Our work unveils key aspects of fractones, extracellular matrix structures that are present in the SVZ that still lack a comprehensive characterization. We show that fractones extensively interact with neural stem cells, whereas some of them are located precisely at pinwheel centers, which are hotspots for adult neurogenesis. Our results also demonstrate that fractones increase in size during aging and that their interactions with neural stem and progenitor cells become more complex in old mice. Last, we show that fractone bulbs are produced by ependymal cells and that their laminin content regulates neural stem cells.
Publisher: American Medical Association (AMA)
Date: 02-1999
DOI: 10.1001/ARCHNEUR.56.2.209
Abstract: Many patients with classic congenital muscular dystrophy have been found to have partial or total deficiency of the alpha2 chain of laminin 2 (merosin). This deficiency has mostly been studied using only 1 antibody against a fragment of the protein. To characterize the expression of laminin alpha2 in the skeletal muscle of patients with laminin alpha2 deficiency using antibodies against 2 different portions of the protein and to correlate the immunochemical findings with clinical phenotype. We studied 4 patients with total lack of laminin alpha2 and 12 with partial laminin alpha2 deficiency with immunohistochemical techniques and Western blot analysis. We used antibodies recognizing an 80-kd fragment toward the C-terminus and a 300-kd fragment toward the amino-terminal. Patient characteristics examined were functional compromise, magnetic resonance imaging or computed tomography of the brain, electromyography, evoked potentials, and creatine kinase levels. In 4 patients, immunohistochemical analysis revealed no reactivity to either antibody in 2 patients, the 300-kd fragment alone was partially expressed in 2 patients, the 80-kd fragment alone was partially expressed and in 8 patients, both fragments were partially expressed. Immunoblot analysis revealed bands of reduced intensity and normal molecular weight generally corresponding to the immunohistochemical findings. Absence of both fragments or of one with reduction of the other always produced a severe clinical phenotype, while a milder clinical phenotype was observed when both fragments were partially expressed. Extent of laminin alpha2 deficiency in most cases correlates with clinical phenotype but not with peripheral and central white matter abnormalities. Skin biopsy specimens may reveal laminin alpha2 deficiency in patients who have normal laminin alpha2 levels in muscle biopsy specimens.
Publisher: Rockefeller University Press
Date: 09-1990
Abstract: It has been previously shown that A-chain and domain(E8)-specific antibodies to laminin that inhibit cell adhesion also interfere with the establishment of epithelial cell polarity during kidney tubule development (Klein, G., M. Langegger, R. Timpl, and P. Ekblom. 1988. Cell. 55:331-341). A monoclonal antibody specific for the integrin alpha 6 subunit, which selectively blocks cell binding to E8, was used to study the receptors involved. Immunofluorescence staining of embryonic kidneys and of organ cultures of metanephric mesenchyme demonstrated coappearance of the integrin alpha 6 subunit and the laminin A-chain in regions where nonpolarized mesenchymal cells convert into polarized epithelial cells. Both epitopes showed marked colocalization in basal areas of tubules, while an exclusive immunostaining for alpha 6 was observed in lateral and apical cell surfaces of the tubular epithelial cells. Organ culture studies demonstrated a consistent inhibition of kidney epithelium development by antibodies against the alpha 6 subunit. The data suggest that the recognition of E8 cell-binding site of laminin by a specific integrin is crucial for the formation of kidney tubule epithelium from undifferentiated mesenchymal stem cells. In some other cell types (endothelium, some ureter cells) an exclusive expression of alpha 6 with no apparent colocalization of laminin A-chain in the corresponding basement membrane was seen. Thus, in these cells, integrins possessing the alpha 6 subunit may bind to laminin isoforms that differ from those synthesized by developing tubules.
Publisher: Springer Science and Business Media LLC
Date: 22-08-2018
Publisher: Informa UK Limited
Date: 02-2002
Publisher: MDPI AG
Date: 26-02-2022
Abstract: The balance between laminin isoforms containing the α5 or the α4 chain in the endothelial basement membrane determines the site of leukocyte diapedesis under inflammatory conditions. Extracellular superoxide dismutase (SOD3) induces laminin α4 expression in tumor blood vessels, which is associated with enhanced intratumor T cell infiltration in primary human cancers. We show now that SOD3 overexpression in neoplastic and endothelial cells (ECs) reduces laminin α5 in tumor blood vessels. SOD3 represses the laminin α5 gene (LAMA5), but LAMA5 expression is not changed in SOD1-overexpressing cells. Transcriptomic analyses revealed SOD3 overexpression to change the transcription of 1682 genes in ECs, with the canonical and non-canonical NF-κB pathways as the major SOD3 targets. Indeed, SOD3 reduced the transcription of well-known NF-κB target genes as well as NF-κB-driven promoter activity in ECs stimulated with tumor necrosis factor (TNF)-α, an NF-κB signaling inducer. SOD3 inhibited the phosphorylation and degradation of IκBα (nuclear factor of the kappa light polypeptide gene enhancer in B-cells inhibitor alpha), an NF-κB inhibitor. Finally, TNF-α was found to be a transcriptional activator of LAMA5 but not of LAMA4 LAMA5 induction was prevented by SOD3. In conclusion, SOD3 is a major regulator of laminin balance in the basement membrane of tumor ECs, with potential implications for immune cell infiltration into tumors.
Publisher: Cold Spring Harbor Laboratory
Date: 05-07-2021
DOI: 10.1101/2021.07.05.450860
Abstract: Development entails patterned emergence of erse cell types within the embryo. In mammals, cells positioned inside the embryo gives rise to the inner cell mass (ICM) that eventually forms the embryo proper. Yet the molecular basis of how these cells recognise their ‘inside’ position to instruct their fate is unknown. Here we show that cells perceive their position through extracellular matrix (ECM) and integrin-mediated adhesion. Provision of ECM to isolated embryonic cells induces ICM specification and alters subsequent spatial arrangement between epiblast (EPI) and primitive endoderm (PrE) cells that emerge within the ICM. Notably, this effect is dependent on integrin β1 activity and involves apical to basal conversion of cell polarity. We demonstrate that ECM-integrin activity is sufficient for ‘inside’ positional signalling and it is required for proper sorting of EPI/PrE cells. Our findings thus highlight the significance of ECM-integrin adhesion in enabling position-sensing by cells to achieve tissue patterning.
Publisher: The Company of Biologists
Date: 04-2006
DOI: 10.1242/JCS.02840
Abstract: T cells develop in the thymus in a highly specialized cellular and extracellular microenvironment. The basement membrane molecule, laminin-5 (LN-5), is predominantly found in the medulla of the human thymic lobules. Using high-resolution light microscopy, we show here that LN-5 is localized in a bi-membranous conduit-like structure, together with other typical basement membrane components including collagen type IV, nidogen and perlecan. Other interstitial matrix components, such as fibrillin-1 or -2, tenascin-C or fibrillar collagen types, were also associated with these structures. Three-dimensional (3D) confocal microscopy suggested a tubular structure, whereas immunoelectron and transmission electron microscopy showed that the core of these tubes contained fibrillar collagens enwrapped by the LN-5-containing membrane. These medullary conduits are surrounded by thymic epithelial cells, which in vitro were found to bind LN-5, but also fibrillin and tenascin-C. Dendritic cells were also detected in close vicinity to the conduits. Both of these stromal cell types express major histocompatibility complex (MHC) class II molecules capable of antigen presentation. The conduits are connected to blood vessels but, with an average diameter of 2 μm, they are too small to transport cells. However, evidence is provided that smaller molecules such as a 10 kDa dextran, but not large molecules (& kDa), can be transported in the conduits. These results clearly demonstrate that a conduit system, which is also known from secondary lymphatic organs such as lymph nodes and spleen, is present in the medulla of the human thymus, and that it might serve to transport small blood-borne molecules or chemokines to defined locations within the medulla.
Publisher: Springer Science and Business Media LLC
Date: 29-04-2021
DOI: 10.1007/S00125-021-05453-Z
Abstract: We and others previously reported the presence of tertiary lymphoid organs (TLOs) in the pancreas of NOD mice, where they play a role in the development of type 1 diabetes. Our aims here are to investigate whether TLOs are present in the pancreas of in iduals with type 1 diabetes and to characterise their distinctive features, in comparison with TLOs present in NOD mouse pancreases, in order to interpret their functional significance. Using immunofluorescence confocal microscopy, we examined the extracellular matrix (ECM) and cellular constituents of pancreatic TLOs from in iduals with ongoing islet autoimmunity in three distinct clinical settings of type 1 diabetes: at risk of diabetes at/after diagnosis and in the transplanted pancreas with recurrent diabetes. Comparisons were made with TLOs from 14-week-old NOD mice, which contain islets exhibiting mild to heavy leucocyte infiltration. We determined the frequency of the TLOs in human type 1diabetes with insulitis and investigated the presence of TLOs in relation to age of onset, disease duration and disease severity. TLOs were identified in preclinical and clinical settings of human type 1 diabetes. The main characteristics of these TLOs, including the cellular and ECM composition of reticular fibres (RFs), the presence of high endothelial venules and immune cell subtypes detected, were similar to those observed for TLOs from NOD mouse pancreases. Among 21 donors with clinical type 1 diabetes who exhibited insulitis, 12 had TLOs and had developed disease at younger age compared with those lacking TLOs. Compartmentalised TLOs with distinct T cell and B cell zones were detected in donors with short disease duration. Overall, TLOs were mainly associated with insulin-containing islets and their frequency decreased with increasing severity of beta cell loss. Parallel studies in NOD mice further revealed some differences in so far as regulatory T cells were essentially absent from human pancreatic TLOs and CCL21 was not associated with RFs. We demonstrate a novel feature of pancreas pathology in type 1 diabetes. TLOs represent a potential site of autoreactive effector T cell generation in islet autoimmunity and our data from mouse and human tissues suggest that they disappear once the destructive process has run its course. Thus, TLOs may be important for type 1 diabetes progression.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 27-07-2010
DOI: 10.1126/SCISIGNAL.2000588
Abstract: Amplification of outside-in chemotactic signaling by inside-out purinergic signaling drives macrophage migration.
Publisher: Elsevier BV
Date: 2007
Publisher: Elsevier BV
Date: 08-2009
Publisher: Elsevier BV
Date: 10-2009
DOI: 10.1016/J.MATBIO.2009.07.006
Abstract: The VWA domain-containing extracellular matrix protein AMACO has not been extensively characterized and its function remains unknown. It has been proposed as a potential cancer marker and carries a rare O-glucosylation and O-fucosylation on its first EGF-like domain. AMACO is a basement membrane associated protein, however its exact localization has not been determined. Here we show by immunogold electron microscopy of mouse kidney and skin that AMACO does not occur within the basement membrane but rather subjacent to the basement membrane at its stromal surface. In skin, AMACO often colocalizes with triple-helical domains of collagen VII containing anchoring fibrils as they emerge from the basal lamina. However, the immunogold patterns for AMACO and the C-terminal end of collagen VII show discrete differences, indicating that AMACO and collagen VII do not colocalize at anchoring plaques. In contrast, the localization pattern of AMACO partially overlaps with that for collagen XVIII. In addition, mouse AMACO was shown to support beta1 integrin-mediated adhesion of a keratinocyte-like cell line, HaCaT, and a fibroblast cell line, Wi26, in an RGD-dependent manner, most likely using an RGD-motif near the C-terminus of AMACO. However, the loss of cell adhesion to the C-terminal part of the human AMACO, due to the unique absence of an RGD sequence in the human protein, suggests that cell adhesion is not AMACO's major function.
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.MATBIO.2017.11.007
Abstract: This review focuses on the complementary roles of MMP-2 and MMP-9 in leukocyte migration into the brain in neuroinflammation, studied mainly in a murine model of experimental autoimmune encephalomyelitis (EAE) that has similarity to the human disease multiple sclerosis. We discuss the cellular sources of MMP-2/MMP-9 in EAE, their sites of activity, and how cleavage of the to-date identified MMP-2/MMP-9 substrates at the blood-brain barrier facilitate leukocyte filtration of the central nervous system (CNS). Where necessary, comparisons are made to inflammatory processes in the periphery and to other MMPs relevant to neuroinflammation. While the general principles concerning MMP-2 and MMP-9 function discussed here are relevant to all inflammatory situations, the details regarding substrates and molecular mechanisms of action are likely to be specific for neuroinflammation.
Publisher: SAGE Publications
Date: 08-2002
DOI: 10.1177/002215540205000813
Abstract: Recent studies suggest important functions for laminin-8 (Ln-8 α4β1γ1) in vascular and blood cell biology, but its distribution in human tissues has remained elusive. We have raised a monoclonal antibody (MAb) FC10, and by enzyme-linked immunoassay (EIA) and Western blotting techniques we show that it recognizes the human Ln α4-chain. Immunoreactivity for the Ln α4-chain was localized in tissues of mesodermal origin, such as basement membranes (BMs) of endothelia, adipocytes, and skeletal, smooth, and cardiac muscle cells. In addition, the Ln α4-chain was found in regions of some epithelial BMs, including epidermis, salivary glands, pancreas, esophageal and gastric glands, intestinal crypts, and some renal medullary tubules. Developmental differences in the distribution of Ln α4-chain were detected in skeletal muscle, walls of vessels, and intestinal crypts. Ln α4- and Ln α2-chains co-localized in BMs of fetal skeletal muscle cells and in some epithelial BMs, e.g., in gastric glands and acini of pancreas. Cultured human pulmonary artery endothelial (HPAE) cells produced Ln α4-chain as M r 180,000 and 200,000 doublet and rapidly deposited it to the growth substratum. In cell-free extracellular matrices of human kidney and lung, Ln α4-chain was found as M r 180,000 protein.
Publisher: Elsevier BV
Date: 03-1999
DOI: 10.1016/S0960-8966(98)00091-1
Abstract: The congenital muscular dystrophies (CMDs) are a heterogeneous group of disorders. Among these, the laminin alpha 2 chain 'merosin' deficient CMD is caused by mutations of the LAMA2 gene on chr 6q2 and Fukuyama CMD is linked to chr 9q31. We report a 7-year-old boy who was born to consanguineous healthy parents. His motor and mental development were slow. Creatine kinase (CK) was elevated (2.100 U/l), and the muscle biopsy was dystrophic. He sat unsupported at 12 months and took his first steps at 3 years of age. At 6 years of age he could walk up to 500 m. He was mentally retarded and spoke single words only. At 1 year, MR imaging of the brain showed abnormal increased periventricular T2-signal, consistent with dysmyelination as well as pontocerebellar hypoplasia and several cerebellar cysts. The pattern of gyration was normal. Follow-up at 4 years showed normalization of the previously abnormal periventricular T2-signal. Immunohistochemical analysis of the skeletal muscle showed normal expression of laminin alpha 2 for a C-terminal antibody and antibodies to the 300 and 150 kDa fragments, as well as of laminins alpha 5, beta 1, beta 2 and gamma 1. The boy has two healthy younger brothers. Linkage analysis excluded the candidate loci on chromosomes 6q2 and 9q31. As such, the patient's data are suggestive of a new form of laminin alpha 2 positive CMD characterized by transient brain dysmyelination, pontocerebellar hypoplasia and mental retardation.
Publisher: Georg Thieme Verlag KG
Date: 08-1997
Abstract: Laminin-2 (merosin) is a heterotrimer composed of alpha 2, beta 1 and gamma 1 chains. Approximately half of the cases with the classical form of congenital muscular dystrophy (CMD) have a deficiency of the laminin alpha 2 chain, encoded by the LAMA2 gene on chromosome 6q22. This disorder is often termed merosin-deficient CMD. Skeletal and cardiac muscle, and the peripheral and central nervous systems, all express laminin alpha 2 and can be affected in merosin-deficient CMD. Normal skin also expresses all three chains of laminin-2 at the epidermal/dermal junction, around hair follicles and in the sensory nerves. Skin biopsies can therefore be used to assess merosin status in patients. We show here an absence of laminin alpha 2 in skin from four cases of CMD with a severe phenotype and abnormal magnetic resonance image (MRI) of the brain, in contrast to normal expression in one case of mild CMD with normal MRI, and in five controls. An additional case of CMD had a partial deficiency of laminin alpha 2 in the skin and severe motor disability, but a normal MRI. Sensory nerves in this case showed normal expression of laminin alpha 2, in contrast to its absence in the severe cases. The expression of laminin beta 1 was also reduced in skin from cases of merosin-deficient CMD. In contrast to human fetal muscle, the laminin alpha 2 protein was not detected in fetal skin up to 23 weeks of gestation. The laminin beta 1 and gamma 1 chains, and the mRNA for laminin alpha 2, however, were present. Studies of mRNA of cultured skin cells suggest that fibroblasts are the major source of laminin alpha 2, not keratinocytes. Our data show that skin is useful for the assessment of merosin status in patients with CMD and that skin fibroblasts may be a useful source of tissue-specific RNA. In addition, we show that there is a tissue-specific difference in the developmental expression of the laminin alpha 2 protein.
Publisher: Springer Science and Business Media LLC
Date: 26-04-2009
DOI: 10.1038/NM.1957
Abstract: Specific inhibition of the entry of encephalitogenic T lymphocytes into the central nervous system in multiple sclerosis would provide a means of inhibiting disease without compromising innate immune responses. We show here that targeting lymphocyte interactions with endothelial basement membrane laminins provides such a possibility. In mouse experimental autoimmune encephalomyelitis, T lymphocyte extravasation correlates with sites expressing laminin alpha4 and small amounts of laminin alpha5. In mice lacking laminin alpha4, laminin alpha5 is ubiquitously expressed along the vascular tree, resulting in marked and selective reduction of T lymphocyte infiltration into the brain and reduced disease susceptibility and severity. Vessel phenotype and immune response were not affected in these mice. Rather, laminin alpha5 directly inhibited integrin alpha(6)beta(1)-mediated migration of T lymphocytes through laminin alpha4. The data indicate that T lymphocytes use mechanisms distinct from other immune cells to penetrate the endothelial basement membrane barrier, permitting specific targeting of this immune cell population.
Publisher: Wiley
Date: 12-1996
DOI: 10.1002/(SICI)1097-0177(199612)207:4<355::AID-AJA1>3.0.CO;2-G
Abstract: Electrospinning is a well-established method for the fabrication of polymer biomaterials, including those with core-shell nanofibers. The variability of structures presents a great range of opportunities in tissue engineering and drug delivery by incorporating biologically active molecules such as drugs, proteins, and growth factors and subsequent control of their release into the target microenvironment to achieve therapeutic effect. The object of study is non-woven core-shell PVA-PEG-SiO
Publisher: Elsevier BV
Date: 04-1991
DOI: 10.1016/0012-1606(91)90419-4
Abstract: Differentiation of the metanephrogenic mesenchyme is triggered by an inductive tissue interaction between an inducer tissue and the mesenchyme. It is generally believed that the epithelial ureter bud acts as an inducer during in vivo development. In response to the inductive stimulus most of the mesenchymal cells convert into epithelial cells, while a small fraction differentiates into stromal cells. In vitro, differentiation of isolated mesenchyme to epithelium can be induced by a variety of embryonic tissues, but nothing is known about the molecular nature of the inducing stimulus. In recent years, large numbers of polypeptide growth factors have been described, which in addition to proliferative effects were shown to exert effects on a variety of biological phenomena such as chemotaxis, inflammation, tissue repair, or induction of embryonic development. We therefore analyzed whether growth factors in the absence of inducer tissue can induce isolated kidney mesenchyme to differentiate into epithelium or interstitium. As expected, both growth and differentiation into epithelium were stimulated by an inducer tissue, the spinal cord. We found that none of the various growth factors tested (including epidermal growth factor, transforming growth factors alpha and beta, insulin-like growth factors I and II, fibroblast growth factor, platelet-derived growth factor, and retinoic acid) could mimick the effect of an inducer tissue, although we tested the factors over a wide concentration range. One of the tested factors, epidermal growth factor (EGF) stimulated the mesenchymal cells to become stromal cells, although it could not stimulate development into epithelium. EGF could stimulate stromal development both when the mesenchyme was cultured in isolation and when the mesenchyme was stimulated by an inducer tissue to become epithelium. The expansion of the stromal compartment in response to EGF treatment occurred at the expense of the epithelial cells, but EGF could not completely suppress the formation of epithelium. These data suggest the presence of EGF receptors in the developing kidney, but since application of soluble EGF leads to abnormal development, soluble EGF cannot be the natural ligand. We suggest that locally produced mitogens with an EGF-like structure may regulate the relative amounts of stroma (interstitium) and epithelium in the developing kidney.
Publisher: The Company of Biologists
Date: 09-1999
Abstract: Integrins α6β1 and α6β4 are cell surface receptors for laminins. Integrin α6-null mice die at birth with severe skin blistering and defects in the cerebral cortex and in the retina. Integrin α3β1 can associate with laminins and other ligands. Integrin α3-null mice also die at birth, with kidney and lung defects at late stages of development, and moderate skin blistering. To investigate possible overlapping functions between α3 and α6 integrins, we analyzed the phenotype of compound α3−/−/α6−/− mutant embryos. Double homozygous mutant embryos were growth-retarded and displayed several developmental defects not observed in the single mutant animals. First, limb abnormalities characterized by an absence of digit separation and the fusion of preskeletal elements were observed. Further analyses indicated a defect in the apical ectodermal ridge, an essential limb organizing center. In the double mutant, the ridge appeared flattened, and ridge cells did not show a columnar morphology. A strong reduction in ridge cell proliferation and alterations of the basal lamina underlying the ectoderm were observed. These results suggest that α3 and α6 integrins are required for the organization or compaction of presumptive apical ectodermal ridge cells into a distinct differentiated structure. Additional defects were present: an absence of neural tube closure, bilateral lung hypoplasia, and several abnormalities in the urogenital tract. Finally, an aggravation of brain and eye lamination defects was observed. The presence of novel phenotypes in double mutant embryos demonstrates the synergism between α3 and α6 integrins and their essential roles in multiple processes during embryogenesis.
Publisher: Portland Press Ltd.
Date: 27-10-2011
DOI: 10.1042/BJ20110584
Abstract: The α2β1 antagonist rhodocetin from Calloselasma rhodostoma is a heterotetrameric CLRP (C-type lectin-related protein) consisting of four distinct chains, α, β, γ and δ. Via their characteristic domain-swapping loops, the in idual chains form two subunits, αβ and γδ. To distinguish the four chains which share similar molecular masses and high sequence homologies, we generated 11 mAbs (monoclonal antibodies) with different epitope specificities. Four groups of distinct mAbs were generated: the first targeted the rhodocetin β chain, the second group bound to the αβ subunit mostly in a conformation-dependent manner, the third group recognized the γδ subunit only when separated from the αβ subunit, whereas a fourth group interacted with the γδ subunit both in the heterotetrameric molecule and complexed with the integrin α2 A-domain. Using the specific mAbs, we have shown that the rhodocetin heterotetramer dissociates into the αβ and γδ subunit upon binding to the integrin α2 A-domain at both the molecular and cellular levels. After dissociation, the γδ subunit firmly interacts with the α2β1 integrin, thereby blocking it, whereas the rhodocetin αβ subunit is released from the complex. The small molecular interface between the αβ and γδ subunits within rhodocetin is mostly mediated by charged residues, which causes the two dissociated subunits to have hydrophilic surfaces.
Publisher: Elsevier BV
Date: 02-2002
Publisher: Elsevier BV
Date: 10-2005
DOI: 10.1016/J.HUMPATH.2005.07.013
Abstract: Hirschsprung disease (HD), a developmental disorder, is associated with failure of enteric ganglia formation. Signaling molecules, including secreted basement membrane molecules, derived from the mesenchyme of the gut wall play an important role in the colonization and/or differentiation of the enteric nervous system. The current study aims to define the possible alterations of laminins involved in the pathogenesis of HD. Expression of the various laminin alpha, beta, and gamma chains, was assessed in the aganglionic, transitional, and ganglionic bowel segments of patients with HD or with other motor disorders. Cytoskeletal, neuronal, and glial markers were also included in this study. The major finding highlighted by the present work concerns the clear identification and location of myenteric aganglionic plexuses in HD with some of the laminin antibodies, which reveal a peripheral nerve type of differentiation. Furthermore, we could show an increase of laminin alpha5 chain immunostaining in the dilated muscle of the ganglionic bowel upstream the distal aganglionic region in a subgroup of patients with HD, as well as a relocalization of laminin alpha2 chain in the subepithelial basement membrane. Overall, these basement membrane molecules could provide useful markers for diagnosis of aganglionosis or hypoganglionosis.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 21-07-2023
Abstract: The gelatinases, matrix metalloproteinase 2 (MMP-2) and MMP-9, are key for leukocyte penetration of the brain parenchymal border in neuroinflammation and the functional integrity of this barrier however, it is unclear which MMP substrates are involved. Using a tailored, sensitive, label-free mass spectrometry–based secretome approach, not previously applied to nonimmune cells, we identified 119 MMP-9 and 21 MMP-2 potential substrates at the cell surface of primary astrocytes, including known substrates (β-dystroglycan) and a broad spectrum of previously unknown MMP-dependent events involved in cell-cell and cell-matrix interactions. Using neuroinflammation as a model of assessing compromised astroglial barrier function, a selection of the potential MMP substrates were confirmed in vivo and verified in human s les, including vascular cell adhesion molecule–1 and neuronal cell adhesion molecule. We provide a unique resource of potential MMP-2/MMP-9 substrates specific for the astroglia barrier. Our data support a role for the gelatinases in the formation and maintenance of this barrier but also in astrocyte-neuron interactions.
Publisher: Public Library of Science (PLoS)
Date: 27-10-2014
Publisher: Elsevier BV
Date: 04-2018
Publisher: Elsevier BV
Date: 06-1991
DOI: 10.1016/S0272-6386(12)80329-5
Abstract: Epithelial cells have a polarized morphology, with distinct basal, lateral, and apical cell surfaces. It would be of considerable interest to know how the polarized morphology develops during embryogenesis. Both the tubular and glomerular epithelial cells of the kidney develop from mesenchymal stem cells during embryogenesis. A unique conversion of nonpolar cells to polarized epithelial cells thus occurs in the embryonic kidney. This conversion also occurs in vitro if the mesenchymal cells are properly induced. Organ cultures of mesenchymal cells from the mouse embryonic kidney have therefore been much used to study the development of epithelial cell polarity. We have used this model system to study the role of basement membrane glycoproteins in development. The results obtained suggest that laminins are particularly important for epithelial cell development. There are many different types of laminins. Developing kidney tubule cells synthesize a laminin isoform with the chain composition A-B1-B2, and it seems to promote development by interacting with specific integrin receptors on the cell surface. The mesenchymal stem cells also produce laminin B chains, but not the A chain, and they also lack the integrin receptor that interacts with A-B1-B2 laminin.
Publisher: Elsevier BV
Date: 11-2003
DOI: 10.1016/S0012-1606(03)00446-9
Abstract: Laminin-alpha5 chain was localized in all epithelial basement membranes (BMs) of mouse submandibular gland (SMG) from the onset of branching morphogenesis and became restricted to BMs of epithelial ducts in the adult. To investigate whether the laminin-alpha5 chain plays a role in branching morphogenesis, a set of cell-adhesive peptides from the C-terminal globular domains (LG1-5) was tested for their effects in SMG organ cultures. One peptide, LVLFLNHGH (A5G77f), which represents a sequence located in the connecting loop between strands E and F of LG4, perturbed branching morphogenesis and resulted in irregularities in the contours of epithelial structures, with formation of deep clefts. The data suggest a role for the laminin-alpha5 LG4 module in the development of the duct system, rather than in the bifurcation of epithelial clusters. The epithelial BM of A5G77f-peptide-treated explants was continuous, which was in contrast to our previous finding of impaired epithelial BM assembly in explants treated with the laminin-alpha1 LG4 module peptide, or with a monoclonal antibody against this domain. A5G77f also perturbed in vitro development of lung and kidney. These results suggest a crucial role for the LG4 module of laminin-alpha5 in epithelial morphogenesis that is distinct from that of the laminin-alpha1 LG4.
Publisher: Elsevier BV
Date: 05-2015
DOI: 10.1016/J.JNEUROIM.2015.03.014
Abstract: Myo9b regulates leukocyte migration by controlling RhoA signaling. Here we assessed its role in active experimental autoimmune encephalomyelitis (EAE). Myo9b(-/-) mice show a delay in the onset of EAE symptoms. The delay in disease onset was accompanied by reduced numbers of Th1 and Th17 cells in the CNS. Myo9b(-/-) mice showed no recovery from disease symptoms and exhibited elevated numbers of both Th17 cells and CD11b+ macrophages. Bone marrow chimeric mice demonstrated that the absence of a leukocyte source of Myo9b was responsible for the delayed leukocyte infiltration into the CNS, delayed EAE onset and lack of recovery.
Publisher: Wiley
Date: 18-12-2017
DOI: 10.1113/JP275105
Publisher: Wiley
Date: 2005
DOI: 10.1002/GENE.20154
Abstract: Laminins are heterotrimeric glycoproteins of the basement membranes. Laminin 1 (alpha1, beta1, gamma1) is the major laminin expressed during early mouse embryogenesis. To gain access to the physiological function of laminin alpha1 chain, we developed a conditionally null allele of its encoding gene (Lama1) using the cre/loxP system. Floxed-allele-carrying mice (Lama1(flox/flox)) display no overt phenotype. Lama1(flox/flox) mice were crossed with transgenic deleter mice (CMV-Cre) to generate Lama1-deficient mice (Lama1(Delta/Delta)). Lama1(Delta/Delta) embryos die during the early postimplantation period after embryonic day 6.5. They lack Reichert's membrane, an extraembryonic basement membrane in which laminin alpha1 is normally highly expressed. In parallel, Lama1(Delta/Delta) embryos display 1) parietal and visceral endoderm differentiation defects with altered expression of cytokeratin 19 and GATA4, respectively, and 2) an induction of apoptosis. This new mouse model is of particular interest as it will allow time- and tissue-specific inactivation of the Lama1 gene in various organs.
Publisher: Wiley
Date: 19-07-2004
DOI: 10.1002/CNCR.20397
Abstract: The authors previously sought to identify novel markers of glioma invasion and recurrence. Their research demonstrated that brain gliomas overexpressed a subset of vascular basement components, laminins, that contained the alpha4 chain. One of these laminins, laminin-8, was found to be present in highly invasive and malignant glioblastoma multiforme (GBM) (Grade 4 astrocytoma) its expression was associated with a decreased time to tumor recurrence, and it was found in vitro to promote invasion of GBM cell lines. In the current study, the authors studied glial tumors of different grades in an attempt to correlate laminin-8 expression with tumor recurrence and patient survival. Immunohistochemistry and Western blot analysis were used to detect laminin isoforms of interest. Using immunohistochemistry and Western blot analysis, the authors confirmed high levels of laminin-8 expression in approximately 75% of the GBM cases examined and in their adjacent tissues, whereas astrocytomas of lower grades expressed for the most part a different isoform, laminin-9, which also was found in low amounts in normal brain tissue and benign meningiomas. Overexpression of laminin-8 in GBM was found to be associated with a statistically significant shorter time to tumor recurrence (P < 0.0002) and a decreased patient survival time (P < 0.015). The data suggest that laminin-8, which may facilitate tumor invasion, contributes to tumor regrowth after therapy. Laminin-8 may be used as a predictor of tumor recurrence and patient survival and as a potential molecular target for glioma therapy.
Publisher: Wiley
Date: 12-1996
Abstract: The mechanism of adhesion of purified mouse polymorphonuclear granulocytes (PMN) to extracellular matrix proteins characteristic of basement membranes and the interstitium has been investigated and compared with the adhesion of a mouse progranulocytic cell line, 32DC13, and a mouse monocytic cell line, WEHI 78/24. All three cell types bound specifically to fibronectin and vitronectin to different degrees under different cellular activation states. 32DC13 bound to fibronectin and vitronectin strongly, and this binding increased upon cellular activation with phorbol 12-myristate-13-acetate (PMA) but not with formyl-Met-Leu-Phe. Only 32DC13 showed significant binding to laminin-1. By contrast, WEHI 78/24 and PMN bound only fibronectin and vitronectin this binding was weak and was altered only marginally upon activation with PMA. In the case of WEHI 78/24, a slight increase in adhesion both to fibronectin and to vitronectin was observed after cellular activation with PMA, while PMN adhesion to both substrates was slightly reduced. The mechanism of binding to fibronectin and vitronectin was similar in the three cell types. The integrin alpha5 beta1 mediated fibronectin adhesion, demonstrating for the first time the existence of a functionally active beta1 integrin on mouse PMN. Vitronectin binding was mediated by alpha(v) beta3, as demonstrated by the ability of alpha(v)-specific cyclic L-Arg-L-Gly-L-Asp-D-Phe-L-Val (RGDfV) peptide (EMD66203), and anti-beta3 antibody to inhibit cell adhesion. 32DC13 adhesion to laminin-1 was via the alpha6 beta1 integrin. None of the three cell types tested bound to the basement membrane proteins collagen type IV and perlecan, or to the interstitial stromal constituents tenascin, collagen types I, V and VI. Interestingly, perlecan and collagen type IV were found to repel all three cell types. The relative inability of PMN, WEHI 78/24, and 32DC13 to bind to extracellular matrix proteins characteristic of basement membranes and their ability to bind inflammatory markers of the interstitium is discussed with respect to leukocyte extravasation processes.
Publisher: eLife Sciences Publications, Ltd
Date: 05-10-2022
DOI: 10.7554/ELIFE.57520
Abstract: The blood-brain barrier (BBB) limits the entry of leukocytes and potentially harmful substances from the circulation into the central nervous system (CNS). While BBB defects are a hallmark of many neurological disorders, the cellular heterogeneity at the neurovascular interface, and the mechanisms governing neuroinflammation are not fully understood. Through single-cell RNA sequencing of non-neuronal cell populations of the murine cerebral cortex during development, adulthood, ageing, and neuroinflammation, we identify reactive endothelial venules, a compartment of specialized postcapillary endothelial cells that are characterized by consistent expression of cell adhesion molecules, preferential leukocyte transmigration, association with perivascular macrophage populations, and endothelial activation initiating CNS immune responses. Our results provide novel insights into the heterogeneity of the cerebral vasculature and a useful resource for the molecular alterations associated with neuroinflammation and ageing.
Publisher: Oxford University Press (OUP)
Date: 23-05-2018
Abstract: Leukocyte entry into the CNS is a crucial step in the development of multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE). Adhesion molecules mediating the docking of leukocytes to the endothelium of the blood–brain barrier (BBB) represent valuable targets for interference with the disease. However, little is known about the adhesion and signaling mechanisms in endothelial cells that mediate the diapedesis through the BBB. Here, we show that conditional Tie-2-Cre driven gene inactivation of CD99L2 inhibits leukocyte entry into the CNS during active MOG35-55-induced EAE and alleviates severity of the disease. No detrimental effect on the immune response was observed. The number of perivascular cuffs around vessels of the CNS was reduced, as was the number of inflammatory foci, sites of demyelination and expression levels of pro-inflammatory cytokines. Three-dimensional analysis of vibratome sections of the CNS revealed an accumulation of leukocytes between endothelial cells and the underlying basement membrane, whereas leukocyte docking to the luminal surface of the endothelium of the BBB was unaffected. Collectively, these results suggest that CD99L2 participates in the development of EAE by supporting diapedesis of leukocytes through the endothelial basement membrane of blood vessels of the BBB in the CNS. CD99L2 gene-inactivation interferes with EAE by inhibiting diapedesis of leukocytes through the endothelial basement membrane of blood vessels of the BBB in the CNS.
Publisher: Springer Science and Business Media LLC
Date: 07-06-2021
DOI: 10.1038/S41467-021-23644-5
Abstract: A major deficit in tissue engineering strategies is the lack of materials that promote angiogenesis, wherein endothelial cells from the host vasculature invade the implanted matrix to form new blood vessels. To determine the material properties that regulate angiogenesis, we have developed a microfluidic in vitro model in which chemokine-guided endothelial cell sprouting into a tunable hydrogel is followed by the formation of perfusable lumens. We show that long, perfusable tubes only develop if hydrogel adhesiveness and degradability are fine-tuned to support the initial collective invasion of endothelial cells and, at the same time, allow for matrix remodeling to permit the opening of lumens. These studies provide a better understanding of how cell-matrix interactions regulate angiogenesis and, therefore, constitute an important step towards optimal design criteria for tissue-engineered materials that require vascularization.
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.IJMM.2018.05.004
Abstract: Staphylococcus aureus is the most frequent pathogen causing diabetic foot infections. Here, we investigated the degree of bacterial virulence required to establish invasive tissue infections in diabetic organisms. Staphylococcal isolates from diabetic and non-diabetic foot ulcers were tested for their virulence in in vitro functional assays of host cell invasion and cytotoxicity. Isolates from diabetes mellitus type I/II patients exhibited less virulence than isolates from non-diabetic patients, but were nevertheless able to establish severe infections. In some cases, non-invasive isolates were detected deep within diabetic wounds, even though the strains were non-pathogenic in cell culture models. Testing of defined isolates in murine footpad injection models revealed that both low- and high-virulent bacterial strains persisted in higher numbers in diabetic compared to non-diabetic hosts, suggesting that hyperglycemia favors bacterial survival. Additionally, the bacterial load was higher in NOD mice, which have a compromised immune system, compared to C57Bl/6 mice. Our results reveal that high as well as low-virulent staphylococcal strains are able to cause soft tissue infections and to persist in diabetic humans and mice, suggesting a reason for the frequent and endangering infections in patients with diabetes.
Publisher: Elsevier BV
Date: 03-1996
DOI: 10.1016/S0140-6736(96)91274-X
Abstract: The alpha2 chain of laminin-2 (merosin), encoded by a gene on chromosome 6q22, is deficient in about half the cases of congenital muscular dystrophy. Diagnosis of this condition has relied on immunocytochemical analysis of the alpha2 chain in muscle biopsy specimens. We have observed that normal skin also expresses laminin alpha2 in the basement membrane at the junction of the dermis and epidermis. Here we have investigated laminin alpha2 deficiency in skin biopsy specimens from two patients with congenital muscular dystrophy. Two patients with severe congenital muscular dystrophy gave informed consent to a skin biopsy. The girl was aged 10 and the boy was aged 7. The specimens were labelled with a commercially available mouse monoclonal antibody and a rat monoclonal antibody (4H8-2), which recognise an 80 and a 380 kDa fragment of the alpha2 chain, respectively. The antibodies were visualised by standard methods. A muscle biopsy specimen was available for each case, and was processed with the skin biopsy s les (from the girl a few months previously, from the boy at age 14 days). Skin biopsies were done on four controls with normal expression of laminin alpha2 on their skeletal muscle fibres. FINDINGS We did not detect laminin alpha2 in skin specimens from either case, although the controls were positive. The muscle biopsy specimens from the girl showed a few fibres, with traces of laminin alpha2 those from the boy showed no laminin alpha2. Skin biopsy specimens will provide a useful alternative to muscle biopsy s les for the assessment of laminin-2 (merosin) status in congenital muscular dystrophy.
Publisher: Rockefeller University Press
Date: 07-09-2015
DOI: 10.1084/JEM.20150165
Abstract: Inactivating mutations of the NF-κB essential modulator (NEMO), a key component of NF-κB signaling, cause the genetic disease incontinentia pigmenti (IP). This leads to severe neurological symptoms, but the mechanisms underlying brain involvement were unclear. Here, we show that selectively deleting Nemo or the upstream kinase Tak1 in brain endothelial cells resulted in death of endothelial cells, a rarefaction of brain microvessels, cerebral hypoperfusion, a disrupted blood–brain barrier (BBB), and epileptic seizures. TAK1 and NEMO protected the BBB by activating the transcription factor NF-κB and stabilizing the tight junction protein occludin. They also prevented brain endothelial cell death in a NF-κB–independent manner by reducing oxidative damage. Our data identify crucial functions of inflammatory TAK1–NEMO signaling in protecting the brain endothelium and maintaining normal brain function, thus explaining the neurological symptoms associated with IP.
Publisher: Elsevier BV
Date: 10-2020
Publisher: American Diabetes Association
Date: 17-07-2013
DOI: 10.2337/DB13-0543
Publisher: Proceedings of the National Academy of Sciences
Date: 21-06-2010
Abstract: Directional motility is a fundamental function of immune cells, which are recruited to sites of pathogen invasion or tissue damage by chemoattractant signals. To move, cells need to generate lamellipodial membrane protrusions at the front and retract the trailing end. These elementary events are initiated by Rho-family GTPases, which cycle between active GTP-bound and inactive GDP-bound states. How the activity of these “molecular switches” is spatially coordinated is only beginning to be understood. Here, we show that myosin IXb (Myo9b), a Rho GTPase-activating protein (RhoGAP) expressed in immune cells, is essential for coordinating the activity of Rho. We generated Myo9b-deficient mice and show that Myo9b −/− macrophages have strikingly defective spreading and polarization. Furthermore, Myo9b −/− macrophages fail to generate lamellipodia in response to a chemoattractant, and migration in a chemotactic gradient is severely impaired. Inhibition of Rho rescues the Myo9b −/− phenotype, but impairs tail retraction. We also found that Myo9b is important in vivo. Chemoattractant-induced monocyte recruitment to the peritoneal cavity is substantially reduced in Myo9b −/− mice. Thus, we identify the “motorized Rho inhibitor” Myo9b as a key molecular component required for spatially coordinated cell shape changes and motility.
Publisher: American Association for Cancer Research (AACR)
Date: 15-06-2004
DOI: 10.1158/0008-5472.CAN-04-0291
Abstract: Laminin-8 (α4β1γ1) is one of the major laminin isoforms expressed in vascular endothelial basement membranes. Here we show that deletion of laminin-8 in mice affects angiogenesis under pathological conditions. Murine tumor models used in laminin α4-deficient mice results in hyperneovascularization and significant promotion of tumor growth and metastasis. The higher tumor growth rates in mutant mice correlate with decreased tumor cell apoptosis. Depletion of laminin α4 chain may alter the structure of vascular basement membranes, leading to increased angiogenesis. Our data suggest that the laminin-8 plays a critical role in the regulation of pathological angiogenesis.
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.CELREP.2016.12.092
Abstract: Endothelial basement membranes constitute barriers to extravasating leukocytes during inflammation, a process where laminin isoforms define sites of leukocyte exit however, how this occurs is poorly understood. In addition to a direct effect on leukocyte transmigration, we show that laminin 511 affects endothelial barrier function by stabilizing VE-cadherin at junctions and downregulating expression of CD99L2, correlating with reduced neutrophil extravasation. Binding of endothelial cells to laminin 511, but not laminin 411 or non-endothelial laminin 111, enhanced transendothelial cell electrical resistance (TEER) and inhibited neutrophil transmigration. Data suggest that endothelial adhesion to laminin 511 via β1 and β3 integrins mediates RhoA-induced VE-cadherin localization to cell-cell borders, and while CD99L2 downregulation requires integrin β1, it is RhoA-independent. Our data demonstrate that molecular information provided by basement membrane laminin 511 affects leukocyte extravasation both directly and indirectly by modulating endothelial barrier properties.
Publisher: Wiley
Date: 04-2002
DOI: 10.1046/J.1365-2567.2002.01384.X
Abstract: The gene family of heterotrimeric laminin molecules consists of at least 15 naturally occurring isoforms which are formed by five different alpha, three beta and three gamma subunits. The expression pattern of the in idual laminin chains in the human thymus was comprehensively analysed in the present study. Whereas laminin isoforms containing the laminin alpha1 chain (e.g. LN-1) were not present in the human thymus, laminin isoforms containing the alpha2 chain (LN-2/4) or the alpha5 chain (LN-10/11) were expressed in the subcapsular epithelium and in thymic blood vessels. Expression of the laminin alpha4 chain seemed to be restricted to endothelial cells of the thymus, whereas the LN-5 isoform containing the alpha3 chain could be detected on medullary thymic epithelial cells and weakly in the subcapsular epithelium. As revealed by cell attachment assays, early CD4- CD8- thymocytes which are localized in the thymus beneath the subcapsular epithelium adhered strongly to LN-10/11, but not to LN-1, LN-2/4 or LN-5. Adhesion of these thymocytes to LN-10/11 was mediated by the integrin alpha6beta1. During further development, the cortically localized CD4+ CD8+ thymocytes have lost the capacity to adhere to laminin-10/11. Neither do these cells adhere to any other laminin isoform tested. However, the more differentiated single positive CD8+ thymocytes which were mainly found in the medulla were able to bind to LN-5 which is expressed by medullary epithelial cells. Interactions of CD8+ thymocytes with LN-5 were integrin alpha6beta4-dependent. These results show that interactions of developing human thymocytes with different laminin isoforms are spatially and developmentally regulated.
Publisher: Elsevier BV
Date: 03-1992
DOI: 10.1038/KI.1992.101
Abstract: 1 The polysaccharide from Ganoderma lucidum (PS-G) has been reported to enhance immune responses and to elicit antitumor effects. In our previous study, we found that PS-G efficiently inhibited spontaneously and Fas-enhanced neutrophil apoptosis when cultured in vitro. Since phagocytosis and chemotaxis play essential roles in host defense mediated by neutrophils, it is of great interest to know the effect of PS-G on these two cell functions, and the molecular events leading to these actions. 2 Using latex beads and heat-inactive Escherichia coli serving as particles for neutrophil engulfment, we found that PS-G is able to enhance phagocytic activity of human primary neutrophils and neutrophilic-phenotype cells differentiated from all trans retinoic acid-treated HL-60 cells. 3 Chemotactic assay using Boyden chamber also revealed the ability of PS-G to increase neutrophil migration. 4 Exposure of neutrophils to PS-G time dependently caused increases in protein kinase C (PKC), p38 mitogen-activated protein kinase (MAPK), Hck, and Lyn activities. 5 Results with specific kinase inhibitors indicate that phagocytic action of PS-G was reduced by the presence of wortmannin (Phosphatidylinositol 3-kinase, PI3K inhibitor), pyrazolpyrimidine 2 (Src-family tyrosine kinase inhibitor), Ro318220 (PKC inhibitor), and SB203580 (p38 MAPK inhibitor), but not by PD98059 (mitogen-activated protein/ERK kinase inhibitor). Moreover, chemotactic action of PS-G requires the activities of PI3K, p38 MAPK, Src tyrosine kinases and PKC. 6 All these results demonstrate the abilities of PS-G to enhance neutrophil function in phagocytosis and chemotaxis, and further provide evidence to strengthen the beneficial remedy of G. lucidum in human to enhance defense system.
Publisher: Wiley
Date: 06-1987
Abstract: The mechanism of iron uptake and the changes which occur during cellular development of muscle cells were investigated using primary cultures of chick embryo breast muscle. Replicating presumptive myoblasts were examined in exponential growth and after growth had plateaued. These were compared to the terminally differentiated cell type, the myotube. All cells, regardless of the state of growth or differentiation, had specific receptors for transferrin. Presumptive myoblasts in exponential growth had more transferrin receptors (3.78 +/- 0.24 X 10(10) receptors/micrograms DNA) than when ision had ceased (1.70 +/- 0.14 X 10(10) receptors/micrograms DNA), while myotubes had 3.80 +/- 0.26 X 10(10) receptors/micrograms DNA. Iron uptake occurred by receptor-mediated endocytosis of transferrin. While iron was accumulated by the cells, apotransferrin was released in an undegraded form. There was a close correlation between the molar rates of endocytosis of transferrin and iron. Maximum rates of iron uptake were significantly higher in myotubes than in presumptive myoblasts in either exponential growth or after growth had plateaued. There were two rates of exocytosis of transferrin, implying the existence of two intracellular pathways for transferrin. These experiments demonstrate that iron uptake by muscle cells in culture occurs by receptor-mediated endocytosis of transferrin and that transferrin receptor numbers and the kinetics of transferrin and iron uptake vary with development of the cells.
Publisher: The Company of Biologists
Date: 2014
DOI: 10.1242/JCS.141556
Abstract: Here we identify a role for the matrilin-2 (Matn2) extracellular matrix protein in controlling early steps of myogenic differentiation. We observed Matn2 deposition around proliferating, differentiating and fusing myoblasts in culture and during muscle regeneration in vivo. Matn2 silencing delayed expression of the Cdk inhibitor p21 and of the Nfix, MyoD, Myog myogenic genes, explaining the retarded cell cycle exit and myoblast differentiation. Matn2 expression rescue restored differentiation and the expression of p21 and of the myogenic genes. TGF-β1 inhibited myogenic differentiation at least in part by repressing Matn2 expression, which inhibited the onset of a positive feedback loop whereby Matn2 and Nfix activate each other's expression as well as myoblast differentiation. In vivo, myoblast cell cycle arrest and muscle regeneration was delayed in Matn2−/− relative to wild-type mice. Trf3 and myogenic gene expression levels robustly dropped in Matn2−/− fetal limbs and in differentiating primary myoblast cultures, establishing Matn2 as a key modulator of the regulatory cascade that initiates terminal myogenic differentiation. Our data thus identify Matn2 as a critical component of a genetic switch that modulates tissue repair onset.
Publisher: Springer Science and Business Media LLC
Date: 08-05-2019
DOI: 10.1038/S41419-019-1583-4
Abstract: Mesenchymal stem cells (MSCs) are a population of multipotent cells with a superior ability to promote tissue repair by regulating regeneration and inflammation. Effective application of MSCs in disease treatment relies on the production of relatively homogeneous cell population. However, the cellular heterogeneity and the differentiation trajectories of in vitro expanded MSCs remain largely unclear. We profiled the transcriptomes of 361 single MSCs derived from two umbilical cords (UC-MSCs). These UC-MSCs were harvested at different passages and stimulated with or without inflammatory cytokines. Weighted gene correlation network analysis revealed that UC-MSCs surprisingly possess only limited heterogeneity, regardless of donors, and passages. We also found that upon pretreatment with inflammatory cytokines (IFNγ and TNFα), a classical strategy that can improve the efficiency of MSC-based therapy, MSCs exhibited uniformed changes in gene expression. Cell cycle-based principal component analysis showed that the limited heterogeneity identified in these UC-MSCs was strongly associated with their entrance into the G2/M phase. This was further proven by the observation that one featured gene, CD168, was expressed in a cell cycle-dependent manner. When CD168 high UC-MSCs were sorted and cultured in vitro, they again showed similar CD168 expression patterns. Our results demonstrated that in vitro expanded UC-MSCs are a well-organized population with limited heterogeneity dominated by cell cycle status. Thus, our studies provided information for standardization of MSCs for disease treatment.
Publisher: The American Association of Immunologists
Date: 04-2012
Abstract: Type 1 diabetes (T1D) is a chronic autoimmune disease that results from T cell-mediated destruction of pancreatic β cells. CD1d-restricted NKT lymphocytes have the ability to regulate immunity, including autoimmunity. We previously demonstrated that CD1d-restricted type II NKT cells, which carry erse TCRs, prevented T1D in the NOD mouse model for the human disease. In this study, we show that CD4+ 24αβ type II NKT cells, but not CD4/CD8 double-negative NKT cells, were sufficient to downregulate diabetogenic CD4+ BDC2.5 NOD T cells in adoptive transfer experiments. CD4+ 24αβ NKT cells exhibited a memory phenotype including high ICOS expression, increased cytokine production, and limited display of NK cell markers, compared with double-negative 24αβ NKT cells. Blocking of ICOS or the programmed death-1 rogrammed death ligand 1 pathway was shown to abolish the regulation that occurred in the pancreas draining lymph nodes. To our knowledge, these results provide for the first time cellular and molecular information on how type II CD1d-restricted NKT cells regulate T1D.
Publisher: Wiley
Date: 10-07-2012
DOI: 10.1002/GLIA.22383
Abstract: Brain edema is the main cause of death from brain infarction. The polarized expression of the water channel protein aquaporin-4 (AQP4) on astroglial endfeet surrounding brain microvessels suggests a role in brain water balance. Loss of astrocyte foot process anchoring to the basement membrane (BM) accompanied by the loss of polarized localization of AQP4 to astrocytic endfeet has been shown to be associated with vasogenic/extracellular edema in neuroinflammation. Here, we asked if loss of astrocyte polarity is also observed in cytotoxic/intracellular edema following focal brain ischemia after transient middle cerebral artery occlusion (tMCAO). Upon mild focal brain ischemia, we observed diminished immunostaining for the BM components laminin α4, laminin α2, and the proteoglycan agrin, in the core of the lesion, but not in BMs in the surrounding penumbra. Staining for the astrocyte endfoot anchorage protein β-dystroglycan (DG) was dramatically reduced in both the lesion core and the penumbra, and AQP4 and Kir4.1 showed a loss of polarized localization to astrocytic endfeet. Interestingly, we observed that mice deficient for agrin expression in the brain lack polarized localization of β-DG and AQP4 at astrocytic endfeet and do not develop early cytotoxic/intracellular edema following tMCAO. Taken together, these data indicate that the binding of DG to agrin embedded in the subjacent BM promotes polarized localization of AQP4 to astrocyte endfeet. Reduced DG protein levels and redistribution of AQP4 as observed upon tMCAO might therefore counteract early edema formation and reflect a beneficial mechanism operating in the brain to minimize damage upon ischemia.
Publisher: Frontiers Media SA
Date: 30-10-2020
Publisher: Springer Science and Business Media LLC
Date: 06-07-2020
DOI: 10.1038/S41598-020-68120-0
Abstract: Limbal melanocytes, located in the basal epithelial layer of the corneoscleral limbus, represent essential components of the corneal epithelial stem cell niche, but, due to difficulties in their isolation and cultivation, their biological roles and potential for stem cell-based tissue engineering approaches have not been comprehensively studied. Here, we established a protocol for the efficient isolation and cultivation of pure populations of human limbal melanocytes, which could be expanded at high yield by using recombinant laminin (LN)-511-E8 as culture substrate. Co-cultivation of limbal melanocytes with limbal epithelial stem rogenitor cells on fibrin hydrogels pre-incubated with LN-511-E8 resulted in multilayered stratified epithelial constructs within ten days. By reproducing physiological cell–cell and cell–matrix interactions of the native niche environment, these biomimetic co-culture systems provide a promising experimental model for investigating the functional roles of melanocytes in the limbal stem cell niche and their suitability for developing advanced epithelial grafts for ocular surface surface reconstruction.
Publisher: Elsevier BV
Date: 03-2006
DOI: 10.1016/J.DEVCEL.2006.01.015
Abstract: Endocrine pancreatic beta cells require endothelial signals for their differentiation and function. However, the molecular basis for such signals remains unknown. Here, we show that beta cells, in contrast to the exocrine pancreatic cells, do not form a basement membrane. Instead, by using VEGF-A, they attract endothelial cells, which form capillaries with a vascular basement membrane next to the beta cells. We have identified laminins, among other vascular basement membrane proteins, as endothelial signals, which promote insulin gene expression and proliferation in beta cells. We further demonstrate that beta1-integrin is required for the beta cell response to the laminins. The proposed mechanism explains why beta cells must interact with endothelial cells, and it may apply to other cellular processes in which endothelial signals are required.
Publisher: Springer Science and Business Media LLC
Date: 04-03-2016
DOI: 10.1038/NCOMMS10828
Abstract: Acute peritonitis is a frequent medical condition that can trigger severe sepsis as a life-threatening complication. Neutrophils are first-responders in infection but recruitment mechanisms to the abdominal cavity remain poorly defined. Here, we demonstrate that high endothelial venules (HEVs) of the greater omentum constitute a main entry pathway in TNFα-, Escherichia coli (E. coli)- and caecal ligation and puncture-induced models of inflammation. Neutrophil transmigration across HEVs is faster than across conventional postcapillary venules and requires a unique set of adhesion receptors including peripheral node addressin, E-, L-selectin and Mac-1 but not P-selectin or LFA-1. Omental milky spots readily concentrate intra-abdominal E. coli where macrophages and recruited neutrophils collaborate in phagocytosis and killing. Inhibition of the omental neutrophil response exacerbates septic progression of peritonitis. This data identifies HEVs as a clinically relevant vascular recruitment site for neutrophils in acute peritonitis that is indispensable for host defence against early systemic bacterial spread and sepsis.
Publisher: The Company of Biologists
Date: 2022
DOI: 10.1242/DEV.200140
Abstract: Development entails patterned emergence of erse cell types within the embryo. In mammals, cells positioned inside the embryo give rise to the inner cell mass (ICM), which eventually forms the embryo itself. Yet, the molecular basis of how these cells recognise their ‘inside’ position to instruct their fate is unknown. Here, we show that provision of extracellular matrix (ECM) to isolated embryonic cells induces ICM specification and alters the subsequent spatial arrangement between epiblast (EPI) and primitive endoderm (PrE) cells that emerge within the ICM. Notably, this effect is dependent on integrin β1 activity and involves apical-to-basal conversion of cell polarity. We demonstrate that ECM-integrin activity is sufficient for ‘inside’ positional signalling and is required for correct EPI/PrE patterning. Thus, our findings highlight the significance of ECM-integrin adhesion in enabling position sensing by cells to achieve tissue patterning.
Publisher: Springer Science and Business Media LLC
Date: 11-07-2017
DOI: 10.1038/S41598-017-04916-X
Abstract: Optimization of culture conditions for human limbal epithelial stem rogenitor cells (LEPC) that incorporate the in vivo cell-matrix interactions are essential to enhance LEPC ex vivo -expansion and transplantation efficiency. Here, we investigate the efficacy of laminin (LN) isoforms preferentially expressed in the limbal niche as culture matrices for epithelial tissue engineering. Analyses of expression patterns of LN chains in the human limbal niche provided evidence for enrichment of LN-α2, -α3, -α5, -β1, -β2, -β3, -γ1, -γ2 and -γ3 chains in the limbal basement membrane, with LN-α5 representing a signature component specifically produced by epithelial progenitor cells. Recombinant human LN-521 and LN-511 significantly enhanced in vitro LEPC adhesion, migration and proliferation compared to other isoforms, and maintained phenotype stability. The bioactive LN-511-E8 fragment carrying only C-terminal domains showed similar efficacy as full-length LN-511. Functional blocking of α3β1 and α6β1 integrins suppressed adhesion of LEPC to LN-511/521-coated surfaces. Cultivation of LEPC on fibrin-based hydrogels incorporating LN-511-E8 resulted in firm integrin-mediated adhesion to the scaffold and well-stratified epithelial constructs, with maintenance of a progenitor cell phenotype in their (supra)basal layers. Thus, the incorporation of chemically defined LN-511-E8 into biosynthetic scaffolds represents a promising approach for xeno-free corneal epithelial tissue engineering for ocular surface reconstruction.
Publisher: Rockefeller University Press
Date: 05-06-2006
DOI: 10.1084/JEM.20051210
Abstract: The mechanism of leukocyte migration through venular walls in vivo is largely unknown. By using immunofluorescence staining and confocal microscopy, the present study demonstrates the existence of regions within the walls of unstimulated murine cremasteric venules where expression of key vascular basement membrane (BM) constituents, laminin 10, collagen IV, and nidogen-2 (but not perlecan) are considerably lower (& %) than the average expression detected in the same vessel. These sites were closely associated with gaps between pericytes and were preferentially used by migrating neutrophils during their passage through cytokine-stimulated venules. Although neutrophil transmigration did not alter the number/unit area of extracellular matrix protein low expression sites, the size of these regions was enlarged and their protein content was reduced in interleukin-1β–stimulated venules. These effects were entirely dependent on the presence of neutrophils and appeared to involve neutrophil-derived serine proteases. Furthermore, evidence was obtained indicating that transmigrating neutrophils carry laminins on their cell surface in vivo. Collectively, through identification of regions of low extracellular matrix protein localization that define the preferred route for transmigrating neutrophils, we have identified a plausible mechanism by which neutrophils penetrate the vascular BM without causing a gross disruption to its intricate structure.
Publisher: The Endocrine Society
Date: 10-2003
Abstract: Laminin has been proposed to influence the function of human adrenal cortex. We have studied the distribution of laminin (Ln) chains using immunofluorescence in human fetal and adult adrenal cortex. In the fetal gland Ln alpha2- and alpha5-chains were weakly expressed in the definitive zone, whereas Ln alpha4-, beta1-, and gamma1-chains occurred around vessels. In the adult gland, Ln alpha2-, alpha5-, and gamma1-chains were found in epithelial basement membranes (BM) in all cortical zones, Ln alpha4-chain in vessels, Ln beta1-chain in outer zone, and Ln beta2-chain in the two inner zones of the cortex, respectively. Among the integrins in adult gland, integrin alpha(3)-subunit was confined to basal surfaces of cortical cells, alpha(6) to vessels, alpha(1) to the stroma, and alpha(2) diffusely to epithelial cells. Lutheran glycoprotein and dystroglycan occurred in the fetal gland diffusely in the definitive zone and throughout the epithelium in the adult. The isoform composition of BM of the adult adrenal gland is distinct, with Ln-2 and -10 in BM of the outer zone and Ln-4 and -11 in BM of the two inner zones. The results suggest that integrin alpha(3)beta(1) and Lutheran are candidate receptors for Ln-10 and -11, whereas dystroglycan probably binds Ln-2 and -4.
Publisher: Springer Science and Business Media LLC
Date: 1988
DOI: 10.1007/BF00692564
Abstract: This study was conducted to understand whether patients with mild Alzheimer disease (AD) could use general or self-referential mental imagery to improve their recognition of visually presented words. Experiment 1 showed that, unlike healthy controls, patients generally did not benefit from either type of imagery. To help determine whether the patients' inability to benefit from mental imagery at encoding was due to poor memory or due to an impairment in mental imagery, participants performed 4 imagery tasks with varying imagery and cognitive demands. Experiment 2 showed that patients successfully performed basic visual imagery, but degraded semantic memory, coupled with visuospatial and executive functioning deficits, impaired their ability to perform more complex types of imagery. Given that patients with AD can perform basic mental imagery, our results suggest that episodic memory deficits likely prevent AD patients from storing or retrieving general mental images generated during encoding. Overall, the results of both experiments suggest that neurocognitive deficits do not allow patients with AD to perform complex mental imagery, which may be most beneficial to improving memory. However, our data also suggest that intact basic mental imagery and rehearsal could possibly be helpful if used in a rehabilitation multisession intervention approach.
Publisher: Cold Spring Harbor Laboratory
Date: 16-04-2020
DOI: 10.1101/2020.04.15.043190
Abstract: Monocyte differentiation to macrophages is triggered by migration across the endothelial barrier, which is constituted by both endothelial cells and their underlying basement membrane. We address here the role of the endothelial basement membrane laminins (laminins 411 and 511) in this monocyte to macrophage switch. Chimeric mice carrying CX3CR1-GFP bone marrow were employed to track CCL2-induced monocyte extravasation in a cremaster muscle model using intravital microscopy, revealing faster extravasation in mice lacking endothelial laminin 511 ( Tek-cre::Lama5 -/- ) and slower extravasation in mice lacking laminin 411 ( Lama4 -/- ). CX3CR1-GFP low extravasating monocytes were found to have a higher motility at laminin 511 low sites and to preferentially exist vessels at these sites. However, in vitro experiments reveal that this is not due to effects of laminin 511 on monocyte migration mode nor on the tightness of the endothelial barrier. Rather, using an intestinal macrophage replenishment model and in vitro differentiation studies we demonstrate that laminin 511 together with the attached endothelium collectively promote monocyte differentiation to macrophages. Macrophage differentiation is associated with a change in integrin profile, permitting differentiating macrophages to distinguish between laminin 511 high and low areas and to migrate preferentially across laminin 511 low sites. These studies highlight the endothelial basement membrane as a critical site for monocyte differentiation to macrophages, which may be relevant to the differentiation of other cells at vascular niches.
Publisher: The American Association of Immunologists
Date: 15-05-2009
Abstract: An important regulatory suppressive function in autoimmune and other inflammatory processes has been ascribed to CD4+Foxp3+ regulatory T cells (Tregs), which requires direct cell-cell communication between Tregs, effector T cells, and APCs. However, the molecular basis for these interactions has not yet been clarified. We show here that sialoadhesin (Sn), the prototype of the siglec family of sialic acid-binding transmembrane proteins, expressed by resident and activated tissue-infiltrating macrophages, directly binds to Tregs, negatively regulating their expansion in an animal model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE). In this model, macrophages infiltrate the CNS exhibiting tissue-destructing and demyelinating activity, leading to MS-like symptoms. We show here that severity of EAE symptoms is reduced in Sn knockout (KO) mice compared with wild-type littermates due to an up-regulation of CD4+Foxp3+ Treg lymphocytes. Through the use of a Sn fusion protein, Tregs were shown to express substantial amounts of Sn ligand on their cell surface, and direct interaction of Sn+ macrophages with Tregs specifically inhibited Treg but not effector T lymphocyte proliferation. Conversely, blocking of Sn on macrophages by Sn-specific Abs resulted in elevated proliferation of Tregs. Data indicate that Sn+ macrophages regulate Treg homeostasis which subsequently influences EAE progression. We propose a new direct cell-cell interaction-based mechanism regulating the expansion of the Tregs during the immune response, representing a “dialogue” between Sn+ macrophages and Sn-accessible sialic acid residues on Treg lymphocytes.
Publisher: Rockefeller University Press
Date: 18-08-2014
DOI: 10.1084/JEM.20140540
Abstract: The focus of this study is the characterization of human T cell blood–brain barrier migration and corresponding molecular trafficking signatures. We examined peripheral blood and cerebrospinal fluid immune cells from patients under long-term anti–very late antigen-4 (VLA-4)/natalizumab therapy (LTNT) and from CNS specimens. LTNT patients’ cerebrospinal fluid T cells exhibited healthy central-/effector-memory ratios, but lacked CD49d and showed enhanced myeloma cell adhesion molecule (MCAM) expression. LTNT led to an increase of PSGL-1 expression on peripheral T cells. Although vascular cell adhesion molecule-1 (VLA-4 receptor) was expressed at all CNS barriers, P-selectin (PSGL-1-receptor) was mainly detected at the choroid plexus. Accordingly, in vitro experiments under physiological flow conditions using primary human endothelial cells and LTNT patients’ T cells showed increased PSGL-1–mediated rolling and residual adhesion, even under VLA-4 blockade. Adhesion of MCAM+/TH17 cells was not affected by VLA-4 blocking alone, but was abrogated when both VLA-4 and MCAM were inhibited. Consistent with these data, MCAM+ cells were detected in white matter lesions, and in gray matter of multiple sclerosis patients. Our data indicate that lymphocyte trafficking into the CNS under VLA-4 blockade can occur by using the alternative adhesion molecules, PSGL-1 and MCAM, the latter representing an exclusive pathway for TH17 cells to migrate over the blood–brain barrier.
Publisher: Springer Science and Business Media LLC
Date: 26-10-2014
Publisher: The American Association of Immunologists
Date: 2013
Abstract: Matrix metalloproteinases (MMPs) have been implicated in the cleavage of several proinflammatory chemokines, thereby modulating their function and having an impact on the inflammatory process. However, in vivo evidence of such a role remains limited. In this study, we use IL-1β–induced peritonitis as a model for an acute immune response, which is initiated by neutrophil influx followed by macrophage infiltration within a few hours of IL-1β injection into the peritoneal cavity. Using single and double knockout mice for MMP-2 and MMP-9, we show that MMP-2 and MMP-9 act synergistically mainly at the initial step of neutrophil recruitment into the peritoneal cavity. The use of bone marrow chimeric mice revealed the cellular sources of MMP-2 and MMP-9 to be distinct, with resident cells being the source of the former and infiltrating leukocytes the source of the latter. We show that the omentum is the main site of neutrophil entry into the peritoneal cavity, where MMP-2 and MMP-9 act synergistically to potentiate the action of CXCL5 (ENA-78/ LIX), thereby, promoting neutrophil migration into the peritoneal cavity. To our knowledge, this is the first in vivo demonstration of MMP-2 and MMP-9 processing of a chemokine that has been directly correlated with an enhanced chemoattracting function.
Publisher: Society for Neuroscience
Date: 24-08-2011
DOI: 10.1523/JNEUROSCI.0141-11.2011
Abstract: Myelinating glial cells exhibit a spectacular cytoarchitecture, because they polarize on multiple axes and domains. How this occurs is essentially unknown. The dystroglycan–dystrophin complex is required for the function of myelin-forming Schwann cells. Similar to other tissues, the dystroglycan complex in Schwann cells localizes with different dystrophin family members in specific domains, thus promoting polarization. We show here that cleavage of dystroglycan by matrix metalloproteinases 2 and 9, an event that is considered pathological in most tissues, is finely and dynamically regulated in normal nerves and modulates dystroglycan complex composition and the size of Schwann cell compartments. In contrast, in nerves of Dy 2j/2j mice, a model of laminin 211 deficiency, metalloproteinases 2 and 9 are increased, causing excessive dystroglycan cleavage and abnormal compartments. Pharmacological inhibition of cleavage rescues the cytoplasmic defects of Dy 2j/2j Schwann cells. Thus, regulated cleavage may be a general mechanism to regulate protein complex composition in physiological conditions, whereas unregulated processing is pathogenic and a target for treatment in disease.
Publisher: Elsevier BV
Date: 12-1996
DOI: 10.1016/S0945-053X(96)90159-6
Abstract: Laminins, found predominantly in basement membranes, are large glycoproteins consisting of different subsets of alpha, beta and gamma chain subunits. To resolve conflicting data in the literature concerning coexpression of alpha 1 and beta 2 chains, expression of alpha 1 chain was studied with two different antisera against the E3 fragment of laminin alpha 1 chain. Expression of the alpha 1 chain was seen in several types of epithelial basement membranes throughout development, but its expression in rat glomerular basement membranes and some other types of epithelial basement membranes occurred only during early stages of development. By contrast, beta 2 chains were detected by immunofluorescence only during advanced stages of glomerulogenesis and vascular development. By Northern and Western blots, beta 2 chains were detected somewhat earlier, but in situ hybridization revealed that beta 2 chain was also confined to vasculature during the earlier stages. It thus seems that, in the tissues studied here, the expression of alpha 1 and beta 2 chains was mutually exclusive. To explore whether the newly described alpha 5 chain is expressed in locations lacking alpha 1 chain, expression of alpha 5 chain was studied by Northern blots and in situ hybridization. The alpha 5 chain was not uniformly expressed in all embryonic epithelial cell types but was present mainly in epithelial sheets which produce very little alpha 1 chain. There also appeared to be a developmental trend, with alpha 1 chain appearing early and alpha 5 later, in maturing epithelial sheets. The alpha 5 chain could be a major alpha chain of the adult glomerular basement membrane.
Publisher: Cold Spring Harbor Laboratory
Date: 14-12-2016
DOI: 10.1101/093351
Abstract: Fractones are extracellular matrix structures in the neural stem cell niche of the subventricular zone ( SVZ ), where they appear as round deposits named bulbs or thin branching lines called stems. Their cellular origin and what determines their localization at this site is poorly studied and it remains unclear whether they influence neural stem and progenitor cells formation, proliferation and/or maintenance. To address these questions, we analyzed whole mount preparations of the lateral ventricle by confocal microscopy using different extracellular matrix and cell markers. We found that bulbs are rarely connected to stems and that they contain laminin α5 and α2 chains, respectively. Fractone bulbs were profusely distributed throughout the SVZ and appeared associated with the center of pinwheels, a critical site for adult neurogenesis. We demonstrate that bulbs appear at the apical membrane of ependymal cells at the end of the first week after birth. The use of transgenic mice lacking laminin α5 gene expression ( Lama5 ) in endothelium and in FoxJ1-expressing ependymal cells, revealed ependymal cells as the source of laminin α5-containing fractone bulbs. Loss of laminin α5 from bulbs correlated with a 60% increase in cell proliferation, as determined by PH3 staining, and with a selective reduction in the number of quiescent neural stem cells in the SVZ. These results indicate that fractones are a key component of the SVZ and suggest that laminin α5 modulates the physiology of the neural stem cell niche. Our work unveils key aspects of fractones, extracellular matrix structures present in the SVZ that still lack a comprehensive characterization. We show that fractones extensively interact with neural stem cells, whereas some of them are located precisely at pinwheel centers, which are hotspots for adult neurogenesis. Our results also demonstrate that fractones increase in size during aging and that their interactions with NSPCs become more complex in old mice. Lastly, we show that fractone bulbs are produced by ependymal cells and that their laminin content regulates neural stem cells.
Publisher: SAGE Publications
Date: 28-12-2017
Abstract: Perivascular compartments surrounding central nervous system (CNS) vessels have been proposed to serve key roles in facilitating cerebrospinal fluid flow into the brain, CNS waste transfer, and immune cell trafficking. Traditionally, these compartments were identified by electron microscopy with limited molecular characterization. Using cellular markers and knowledge on cellular sources of basement membrane laminins, we here describe molecularly distinct compartments surrounding different vessel types and provide a comprehensive characterization of the arachnoid and pial compartments and their connection to CNS vessels and perivascular pathways. We show that differential expression of plectin, E-cadherin and laminins α1, α2, and α5 distinguishes pial and arachnoid layers at the brain surface, while endothelial and smooth muscle laminins α4 and α5 and smooth muscle actin differentiate between arterioles and venules. Tracer studies reveal that interconnected perivascular compartments exist from arterioles through to veins, potentially providing a route for fluid flow as well as the transport of large and small molecules.
Publisher: Springer Science and Business Media LLC
Date: 20-02-2017
DOI: 10.1038/NCB3476
Publisher: Elsevier BV
Date: 12-2016
DOI: 10.1016/J.MATBIO.2016.05.001
Abstract: Laminin α5 is broadly expressed in the epidermal basement membrane (BM) of mature mice and its elimination at this site (Lama5
Publisher: Elsevier BV
Date: 07-1996
Abstract: Immunochemical techniques were used to determine whether cells of the avascular corneal stroma (keratocytes) have the ability to synthesize thrombo- spondin 1 (TSP1), a glycoprotein originally described in platelets and more recently implicated in regulating cell behavior (e.g., migration) during wound repair in vascular tissue. Immunoprecipitation experiments with metabolically labeled cells showed that bovine keratocytes in preconfluent cultures produced TSP1, but de novo TSP1 production could not be detected in confluent keratocyte cultures. Immunofluorescence studies of the preconfluent cells revealed that the keratocyte TSP1 was distributed in perinuclear granules and peripheral foci. TSP1 expression also was observed in keratocytes cultured in a collagen matrix model of stromal wound healing and, in this model, immunogold labeling revealed TSP1 foci on keratocyte surfaces adjacent to collagen fibers in the matrices. TSP1 expression was not observed in the syncytial keratocytes of normal bovine cornea. The results indicate that keratocytes have the ability to synthesize TSP1, and do so in vitro under conditions which simulate corneal stroma repair, but suggest that keratocytes in a syncytial arrangement (as in the normal cornea) do not make TSP1. TSP1 may play a role in corneal pathologies which induce keratocytes to change from a syncytial to a wound repair phenotype, such as mechanical damage to the stroma. Local production of TSP1 might provide an alternative source to platelet-derived TSP1 during nonvascularized stromal tissue repair.
Publisher: Elsevier BV
Date: 11-1994
Publisher: The Company of Biologists
Date: 06-1991
Abstract: The expression of laminin, a major glycoprotein constituent of basement membranes, was investigated in the rat developing intestine. The biosynthesis of laminin was studied after metabolic labeling of intestinal segments taken at various stages of development the neosynthesized laminin was purified by affinity chromatography on heparin–Sepharose. Immunoblotting and immunoprecipitation experiments allowed us to analyze its constitutive chains. The data show that laminin is synthesized in very large amounts at 16–18 days of gestation concomitant with the onset of intestinal morphogenetic movements, i.e. villus emergence. Evaluation of the relative proportion of in idual laminin polypeptides shows that laminin B1/B2 chains are produced in excess of A chains whatever the developmental stage considered. Interestingly at 17 days of gestation, levels of laminin A subunits are maximal. A second rise in the A/B chain ratio starts around birth and continues until adulthood. These quantitative data are corroborated by the immunocytochemical detection of laminin A and B chains, which revealed a specific spatiotemporal pattern. The finding that laminin A chains are located in the basement membrane of growing villi and of adult crypts raises the possibility that they may be involved in the process of cell growth and/or in the establishment of cell polarity by creating a specialized extracellular microenvironment.
Publisher: Elsevier BV
Date: 05-2012
Publisher: Elsevier BV
Date: 08-2005
DOI: 10.1016/J.MATBIO.2005.05.006
Abstract: A simplification of the laminin nomenclature is presented. Laminins are multidomain heterotrimers composed of alpha, beta and gamma chains. Previously, laminin trimers were numbered with Arabic numerals in the order discovered, that is laminins-1 to -5. We introduce a new identification system for a trimer using three Arabic numerals, based on the alpha, beta and gamma chain numbers. For ex le, the laminin with the chain composition alpha5beta1gamma1 is termed laminin-511, and not laminin-10. The current practice is also to mix two overlapping domain and module nomenclatures. Instead of the older Roman numeral nomenclature and mixed nomenclature, all modules are now called domains. Some domains are renamed or renumbered. Laminin epidermal growth factor-like (LE) domains are renumbered starting at the N-termini, to be consistent with general protein nomenclature. Domain IVb of alpha chains is named laminin 4a (L4a), domain IVa of alpha chains is named L4b, domain IV of gamma chains is named L4, and domain IV of beta chains is named laminin four (LF). The two coiled-coil domains I and II are now considered one laminin coiled-coil domain (LCC). The interruption in the coiled-coil of beta chains is named laminin beta-knob (Lbeta) domain. The chain origin of a domain is specified by the chain nomenclature, such as alpha1L4a. The abbreviation LM is suggested for laminin. Otherwise, the nomenclature remains unaltered.
Publisher: EMBO
Date: 09-12-2016
No related grants have been discovered for Lydia Sorokin.