ORCID Profile
0000-0001-5127-9687
Current Organisations
University of South Australia
,
Centre for Cancer Biology/SA Pathology
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Publisher: American Society of Hematology
Date: 15-11-2001
DOI: 10.1182/BLOOD.V98.10.3165
Abstract: Transfected murine cell lines are commonly used to study the function of many human cytokine or receptor mutants. This study reports the inappropriate activation of the human granulocyte-macrophage colony-stimulating factor (hGM-CSF) receptor by the human GM-CSF antagonist, E21R, when the human receptor is introduced into the murine cell line BaF-B03. E21R-induced proliferation of the BaF-B03 cells is dependent on transfection with both hGM-CSF receptor α and βc subunits. Studies on the underlying mechanism revealed constitutive association between human and mouse βc and GM-CSF receptor-α, tyrosine phosphorylation of mouse and human βc, and association of phosphorylated mouse βc into an activated human GM-CSF receptor complex in response to E21R and GM-CSF. This interspecies receptor cross-talk of receptor signaling subunits may produce misleading results and emphasizes the need to use cell lines devoid of the cognate endogenous receptors for functional analysis of ligand and receptor mutants.
Publisher: MDPI AG
Date: 11-10-2021
DOI: 10.3390/MOLECULES26206120
Abstract: 14-3-3 proteins are abundant, intramolecular proteins that play a pivotal role in cellular signal transduction by interacting with phosphorylated ligands. In addition, they are molecular chaperones that prevent protein unfolding and aggregation under cellular stress conditions in a similar manner to the unrelated small heat-shock proteins. In vivo, amyloid β (Aβ) and α-synuclein (α-syn) form amyloid fibrils in Alzheimer’s and Parkinson’s diseases, respectively, a process that is intimately linked to the diseases’ progression. The 14-3-3ζ isoform potently inhibited in vitro fibril formation of the 40-amino acid form of Aβ (Aβ40) but had little effect on α-syn aggregation. Solution-phase NMR spectroscopy of 15N-labeled Aβ40 and A53T α-syn determined that unlabeled 14-3-3ζ interacted preferentially with hydrophobic regions of Aβ40 (L11-H21 and G29-V40) and α-syn (V3-K10 and V40-K60). In both proteins, these regions adopt β-strands within the core of the amyloid fibrils prepared in vitro as well as those isolated from the inclusions of diseased in iduals. The interaction with 14-3-3ζ is transient and occurs at the early stages of the fibrillar aggregation pathway to maintain the native, monomeric, and unfolded structure of Aβ40 and α-syn. The N-terminal regions of α-syn interacting with 14-3-3ζ correspond with those that interact with other molecular chaperones as monitored by in-cell NMR spectroscopy.
Publisher: Elsevier BV
Date: 02-2000
Publisher: Wiley
Date: 09-1987
DOI: 10.1111/J.1365-2958.1987.TB00518.X
Abstract: Transcriptional activation of nitrogen fixation genes by NifA in Klebsiella pneumoniae requires an upstream NifA binding site. We now report that the introduction of half turns of the DNA helix into the DNA separating the upstream NifA binding site from the downstream promoter element of the nifH promoter decreases NifA-mediated activation to a greater extent than does the introduction of full helical turns. Reducing the spacing between the upstream and downstream elements of the nifH promoter also results in a promoter down phenotype. Introduction of a tight protein-binding site, the lac operator, between the upstream and downstream promoter elements did not render activation of the nifH promoter sensitive to occupancy of this site by the lac repressor. These findings indicate that NifA-mediated activation of transcription requires that NifA is bound upstream, and to the correct face of the DNA helix, in order to interact with downstream transcription factors. This implies that the interaction is brought about by the formation of a DNA loop between upstream and downstream promoter elements rather than by NifA sliding downstream.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-10-2018
Abstract: Bio ersity experiments have shown that species loss reduces ecosystem functioning in grassland. To test whether this result can be extrapolated to forests, the main contributors to terrestrial primary productivity, requires large-scale experiments. We manipulated tree species richness by planting more than 150,000 trees in plots with 1 to 16 species. Simulating multiple extinction scenarios, we found that richness strongly increased stand-level productivity. After 8 years, 16-species mixtures had accumulated over twice the amount of carbon found in average monocultures and similar amounts as those of two commercial monocultures. Species richness effects were strongly associated with functional and phylogenetic ersity. A shrub addition treatment reduced tree productivity, but this reduction was smaller at high shrub species richness. Our results encourage multispecies afforestation strategies to restore bio ersity and mitigate climate change.
Publisher: Elsevier BV
Date: 1992
DOI: 10.1016/0167-5699(92)90025-3
Abstract: The biological properties of GM-CSF, IL-3 and IL-5 are multiple initially described as haemopoietic growth factors, they also regulate inflammation, allergic reactions and cell adherence. The receptors for these three cytokines share a common component which may play a key role in their biological activity. This review describes the potential roles of GM-CSF, IL-3 and IL-5 in inflammation and discusses approaches to modulate their function.
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.CELLSIG.2010.04.004
Abstract: The dimeric 14-3-3 protein family protects cells from apoptosis by regulating pro-apoptotic molecules. Conversely, the cationic lipid sphingosine is associated with physiological apoptosis and induces apoptosis in its own right by a largely undefined mechanism. We show here that sphingosine and 14-3-3 interact directly in the control of cell death. The binding of sphingosine to 14-3-3 proteins renders them phosphorylatable at the dimer interface, an event that abolishes the pro-survival signalling of 14-3-3. Sphingosine kinase 1 reduces availability of sphingosine for interaction with 14-3-3, thus inhibiting cell death and providing a new mechanistic insight into the role of this enzyme in cell survival and oncogenesis. Importantly, FTY720, a sphingosine analogue with apoptotic activity that is currently in phase III clinical trials for multiple sclerosis, acts in a similar manner to sphingosine in potentiating 14-3-3 phosphorylation. The biological significance of 14-3-3 phosphorylation was demonstrated with a non-phosphorylatable 14-3-3zeta mutant which retarded apoptosis induced by sphingosine and FTY720. These results demonstrate that direct association of sphingosine with 14-3-3 is required for 14-3-3 phosphorylation, and that this axis can control cell fate. Furthermore, these results suggest a new therapeutic activity for FTY720 as an anti-cancer agent based on this mechanism.
Publisher: Elsevier BV
Date: 11-1996
Publisher: Elsevier BV
Date: 09-2003
Publisher: Elsevier BV
Date: 02-2002
Publisher: Elsevier BV
Date: 10-1999
DOI: 10.1016/S1357-2725(99)00084-9
Abstract: The cytokines granulocyte-macrophage colony stimulating factor, interleukin-3 and interleukin-5 have overlapping activities on cells expressing their receptors. This is explained by their sharing a receptor signal transduction subunit, beta c. This communal signaling subunit is also required for high affinity binding of all three cytokines. Therapeutic approaches attempting to interfere or modulate haemopoietic cells using cytokines or their analogues can in some instances be limited due to functional redundancy amongst cytokines using shared receptor signaling subunits. Therefore, a better approach would be to develop therapeutics against the shared subunit. Studies examining the GM-CSF, IL-3 and IL-5 receptors have identified the key events leading to functional receptor activation. With this knowledge, it is now possible to identify new targets for the development of a new class of antagonist that blocks the biological activity of all the cytokines utilizing beta c. This approach may be extended to other receptor systems such as IL-4 and IL-13 where receptor activation is dependent on a common signaling and binding subunit.
Publisher: Springer Science and Business Media LLC
Date: 27-09-2016
DOI: 10.1038/NCOMMS12862
Abstract: The 14-3-3 family of adaptor proteins regulate erse cellular functions including cell proliferation, metabolism, adhesion and apoptosis. Platelets express numerous 14-3-3 isoforms, including 14-3-3ζ, which has previously been implicated in regulating GPIbα function. Here we show an important role for 14-3-3ζ in regulating arterial thrombosis. Interestingly, this thrombosis defect is not related to alterations in von Willebrand factor (VWF)–GPIb adhesive function or platelet activation, but instead associated with reduced platelet phosphatidylserine (PS) exposure and procoagulant function. Decreased PS exposure in 14-3-3ζ-deficient platelets is associated with more sustained levels of metabolic ATP and increased mitochondrial respiratory reserve, independent of alterations in cytosolic calcium flux. Reduced platelet PS exposure in 14-3-3ζ-deficient mice does not increase bleeding risk, but results in decreased thrombin generation and protection from pulmonary embolism, leading to prolonged survival. Our studies define an important role for 14-3-3ζ in regulating platelet bioenergetics, leading to decreased platelet PS exposure and procoagulant function.
Publisher: Wiley
Date: 08-2006
DOI: 10.1080/15216540600871118
Abstract: The sphingomyelin pathway is activated in response to many apoptotic stimuli leading to the accumulation of breakdown products ceramide and sphingosine. Ceramide has received much attention as an apoptotic second messenger whereas sphingosine has largely been overlooked as a mediator of apoptosis. Recent studies however provide strong clues to a second messenger role for sphingosine and identification of effectors reveal a possible mechanism involved in sphingosine-mediated cell death. This mini-review overviews the current knowledge of the role of ceramide and sphingosine in apoptosis and discusses their biological effects. The review attempts to reconcile the apoptotic effects of these lipids with the downstream effectors that have been identified.
Publisher: Wiley
Date: 04-2001
DOI: 10.1046/J.1440-1711.2001.00987.X
Abstract: Asthma is a common and complex inflammatory disease of the airways that remains incurable. Current forms of therapy are long term and may exhibit associated side-effect problems. Major participants in the development of an asthma phenotype include the triggering stimuli such as the allergens themselves, cells such as T cells, epithelial cells and mast cells that produce a variety of cytokines including IL-5, GM-CSF, IL-3, IL-4 and IL-13 and chemokines such as eotaxin. Significantly, the eosinophil, a specialized blood cell type, is invariably associated with this disease. The eosinophil has long been incriminated in the pathology of asthma due to its ability to release preformed and unique toxic substances as well as newly formed pro-inflammatory mediators. The regulation of eosinophil production and function is carried out by soluble peptides or factors. Of these IL-5, GM-CSF and IL-3 are of paramount importance as they control eosinophil functional activity and are the only known eosinophilopoietic factors. In addition they regulate the eosinophil life span by inhibiting apoptosis. While one therapeutic approach in asthma is directed at inhibiting single eosinophil products such as leukotrienes or single eosinophil regulators such as IL-5, we believe that the simultaneous inhibition of more than one component is preferable. This may be particularly important with eosinophil regulators in that not only IL-5, but also GM-CSF has been repeatedly implicated in clinical studies of asthma. The fact that GM-CSF is produced by many cells in the body and in copious amounts by lung epithelial cells highlights this need further. Our approach takes advantage of the fact that the IL-5 and GM-CSF receptors (as well as IL-3 receptors) utilize a shared subunit to bind, with high affinity, to these cytokines and the same common subunit mediates signal transduction culminating in all the biological activities mentioned. By generating the monoclonal antibody BION-1 to the cytokine binding region of the common subunit (betac) we have shown that the approach of inhibiting IL-5, GM-CSF and IL-3 binding and the resulting stimulation of eosinophil production and function with a single agent is feasible. Furthermore we have used BION-1 as a tool to crystallize and define the structure of the cytokine binding domain of betac. This knowledge and this approach may lead to the generation of novel therapeutics for the treatment of asthma.
Publisher: Informa UK Limited
Date: 18-01-2012
DOI: 10.3109/08977194.2011.649919
Abstract: Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pluripotent cytokine produced by many cells in the body, which regulates normal and malignant hemopoiesis as well as innate and adaptive immunity. GM-CSF assembles and activates its heterodimeric receptor complex on the surface of myeloid cells, initiating multiple signaling pathways that control key functions such as cell survival, cell proliferation, and functional activation. Understanding the molecular composition of these pathways, the interaction of the various components as well as the kinetics and dose-dependent mechanics of receptor activation provides valuable insights into the function of GM-CSF as well as the related cytokines, interleukin-3 and interleukin-5. This knowledge provides opportunities for the development of new therapies to block the action of these cytokines in hematological malignancy and chronic inflammation.
Publisher: Elsevier BV
Date: 1998
Publisher: Bentham Science Publishers Ltd.
Date: 03-2017
DOI: 10.2174/156652412803833599
Abstract: FTY720 is a recently approved first line therapy for relapsing forms of multiple sclerosis. In this context, FTY720 is a pro-drug, with its anti-multiple sclerosis, immunosuppressive effects largely elicited following its phosphorylation by sphingosine kinase 2 and subsequent modulation of G protein-coupled sphingosine 1-phosphate (S1P) receptor 1 that induces lymphopenia by altering lymphocyte trafficking. A number of other biological effects of FTY720 have, however, been described, including considerable evidence that this drug also has anti-cancer properties. These other effects of FTY720 are independent of S1P receptors, and appear facilitated by modulation of a range of other recently described protein targets by nonphosphorylated FTY720. Here, we review the direct targets of FTY720 that contribute to its anti-cancer properties. We also discuss other recently described protein effectors that, in combination with S1P receptors, appear to contribute to its immunosuppressive effects.
Publisher: Springer Science and Business Media LLC
Date: 15-02-2018
Publisher: Oxford University Press (OUP)
Date: 30-01-2017
DOI: 10.1093/JPE/RTW099
Publisher: Springer Science and Business Media LLC
Date: 03-1298
DOI: 10.1007/BF00337770
Abstract: The nature and contribution of different pregnancy-related complications to future cardiovascular disease (CVD) and its risk factors and the mechanisms underlying these associations remain unclear. We studied associations of pregnancy diabetes mellitus, hypertensive disorders of pregnancy, preterm delivery, and size for gestational age with calculated 10-year CVD risk (based on the Framingham score) and a wide range of cardiovascular risk factors measured 18 years after pregnancy (mean age at outcome assessment, 48 years) in a prospective cohort of 3416 women. Gestational diabetes mellitus was positively associated with fasting glucose and insulin, even after adjustment for potential confounders, whereas hypertensive disorders of pregnancy were associated with body mass index, waist circumference, blood pressure, lipids, and insulin. Large for gestational age was associated with greater waist circumference and glucose concentrations, whereas small for gestational age and preterm delivery were associated with higher blood pressure. The association with the calculated 10-year CVD risk based on the Framingham prediction score was odds ratio 1.31 (95 confidence interval, 1.11-1.53) for preecl sia and 1.26 (95 confidence interval, 0.95-1.68) for gestational diabetes mellitus compared with women without preecl sia and without gestational diabetes mellitus, respectively. Hypertensive disorders of pregnancy and pregnancy diabetes mellitus are independently associated with an increased calculated 10-year CVD risk. Preecl sia may be the better predictor of future CVD because it was associated with a wider range of cardiovascular risk factors. Our results suggest that pregnancy may be an important opportunity for early identification of women at increased risk of CVD later in life.
Publisher: Elsevier
Date: 2005
Publisher: Elsevier BV
Date: 07-2000
Publisher: Elsevier BV
Date: 2018
Publisher: American Society of Hematology
Date: 15-02-2003
DOI: 10.1182/BLOOD-2002-06-1903
Abstract: Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a hematopoietic cytokine that stimulates the production and functional activity of granulocytes and macrophages, properties that have encouraged its clinical use in bone marrow transplantation and in certain infectious diseases. Despite the importance of GM-CSF in regulating myeloid cell numbers and function, little is known about the exact composition and mechanism of assembly of the GM-CSF receptor complex. We have now produced soluble forms of the GM-CSF receptor α chain (sGMRα) and β chain (sβc) and utilized GM-CSF, the GM-CSF antagonist E21R (Glu21Arg), and the βc-blocking monoclonal antibody BION-1 to define the molecular assembly of the GM-CSF receptor complex. We found that GM-CSF and E21R were able to form low-affinity, binary complexes with sGMRα, each having a stoichiometry of 1:1. Importantly, GM-CSF but not E21R formed a ternary complex with sGMRα and sβc, and this complex could be disrupted by E21R. Significantly, size-exclusion chromatography, analytical ultracentrifugation, and radioactive tracer experiments indicated that the ternary complex is composed of one sβc dimer with a single molecule each of sGMRα and of GM-CSF. In addition, a hitherto unrecognized direct interaction between βc and GM-CSF was detected that was absent with E21R and was abolished by BION-1. These results demonstrate a novel mechanism of cytokine receptor assembly likely to apply also to interleukin-3 (IL-3) and IL-5 and have implications for our molecular understanding and potential manipulation of GM-CSF activation of its receptor.
Publisher: Wiley
Date: 09-10-2015
DOI: 10.1111/NPH.13068
Abstract: Environmental selection and dispersal limitation are two of the primary processes structuring biotic communities in ecosystems, but little is known about these processes in shaping soil microbial communities during secondary forest succession. We examined the communities of ectomycorrhizal ( EM ) fungi in young, intermediate and old forests in a C hinese subtropical ecosystem, using 454 pyrosequencing. The EM fungal community consisted of 393 operational taxonomic units ( OTU s), belonging to 21 EM fungal lineages, in which three EM fungal lineages and 11 EM fungal OTU s showed significantly biased occurrence among the young, intermediate and old forests. The EM fungal community was structured by environmental selection and dispersal limitation in old forest, but only by environmental selection in young, intermediate, and whole forests. Furthermore, the EM fungal community was affected by different factors in the different forest successional stages, and the importance of these factors in structuring EM fungal community dramatically decreased along the secondary forest succession series. This study suggests that different assembly mechanisms operate on the EM fungal community at different stages in secondary subtropical forest succession.
Publisher: Elsevier BV
Date: 09-2023
Publisher: Rockefeller University Press
Date: 02-06-1997
Abstract: The receptor for granulocyte/macrophage colony-stimulating factor (GM-CSF) is composed of two chains, α and βc. Both chains belong to the superfamily of cytokine receptors characterized by a common structural feature, i.e., the presence of at least two fibronectin-like folds in the extracellular domain, which was first identified in the growth hormone receptor. The GM-CSF receptor (GMR)-α chain confers low affinity binding only (5–10 nM), whereas the other chain, βc, does not bind GM-CSF by itself but confers high affinity binding when associated with GMR-α (25–100 pM). The present study was designed to define the assembly of the GMR complex at the molecular level through site-directed mutagenesis guided by homology modeling with the growth hormone receptor complex. In our three-dimensional model, R280 of GMR-α, located in the F′–G′ loop and close to the WSSWS motif, is in the vicinity of the ligand Asp112, suggesting the possibility of electrostatic interaction between these two residues. Through site directed mutagenesis, we provide several lines of evidence indicating the importance of electrostatic interaction in ligand–receptor recognition. First, mutagenesis of GMR-αR280 strikingly ablated ligand binding in the absence of β common (βc) ligand binding was restored in the presence of βc with, nonetheless, a significant shift from high (26 pM) toward low affinity (from 2 to 13 nM). The rank order of the dissociation constant for the different GMR-αR280 mutations where Lys & Gln & Met & Asp, suggesting the importance of the charge at this position. Second, a mutant GM-CSF with charge reversal mutation at position Asp112 exhibited a 1,000-fold decrease in affinity in receptor binding, whereas charge ablation or conservative mutations were the least affected (10–20-fold). Third, removal of the charge at position R280 of GMR-α introduced a 10-fold decrease in the association rate constant and only a 2-fold change in the dissociation rate constant, suggesting that R280 is implicated in ligand recognition, possibly through interaction with Asp112 of GM-CSF. For all R280 mutants, the half-efficient concentrations of GM-CSF required for membrane (receptor binding) to nuclear events (c-fos promoter activation) and cell proliferation (thymidine incorporation) were in the same range, indicating that the threshold for biologic activity is governed mainly by the affinity of ligand–receptor interaction. Furthermore, mutation of other residues in the immediate vicinity of R280 was less drastic. Sequence alignment and modeling of interleukin (IL)-3R and IL-5R identified an arginine residue at the tip of a β turn in a highly ergent context at the F′–G′ loop, close to a conserved structural element, the WSXWS motif, suggesting the possibility of a ligand association mechanism similar to the one described herein for GMR.
Publisher: Elsevier BV
Date: 07-2005
Publisher: Springer Science and Business Media LLC
Date: 14-06-2019
DOI: 10.1038/S41598-019-45156-5
Abstract: Soil properties and terrain attributes are of great interest to explain and model plant productivity and community assembly (hereafter P& CA). Many studies only s le surface soils, and may therefore miss important variation of deeper soil levels. We aimed to identify a critical soil depth in which the relationships between soil properties and P& CA were strongest due to an ideal interplay among soil properties and terrain attributes. On 27 plots in a subtropical Chinese forest varying in tree and herb layer species richness and tree productivity, 29 soil properties in six depth columns and four terrain attributes were analyzed. Soil properties varied with soil depth as did their interrelationships. Non-linearity of soil properties led to critical soil depths in which different P& CA characteristics were explained best (using coefficients of determination). The strongest relationship of soil properties and terrain attributes to most of P& CA characteristics (adj. R 2 ~ 0.7) was encountered using a soil column of 0–16 cm. Thus, depending on the biological signal one is interested in, soil depth s ling has to be adapted. Considering P& CA in subtropical broad-leaved secondary forests, we recommend s ling one bulk s le of a column from 0 cm down to a critical soil depth of 16 cm.
Publisher: Springer Science and Business Media LLC
Date: 05-04-2012
Publisher: Public Library of Science (PLoS)
Date: 19-03-2013
Publisher: Springer Science and Business Media LLC
Date: 04-2001
DOI: 10.1007/BF02981954
Publisher: Springer Science and Business Media LLC
Date: 12-12-2017
DOI: 10.1038/ONC.2016.428
Publisher: Wiley
Date: 22-11-2013
Publisher: Elsevier BV
Date: 12-2015
DOI: 10.1016/J.DEVCEL.2015.11.026
Abstract: ROCK signaling causes epidermal hyper-proliferation by increasing ECM production, elevating dermal stiffness, and enhancing Fak-mediated mechano-transduction signaling. Elevated dermal stiffness in turn causes ROCK activation, establishing mechano-reciprocity, a positive feedback loop that can promote tumors. We have identified a negative feedback mechanism that limits excessive ROCK signaling during wound healing and is lost in squamous cell carcinomas (SCCs). Signal flux through ROCK was selectively tuned down by increased levels of 14-3-3ζ, which interacted with Mypt1, a ROCK signaling antagonist. In 14-3-3ζ(-/-) mice, unrestrained ROCK signaling at wound margins elevated ECM production and reduced ECM remodeling, increasing dermal stiffness and causing rapid wound healing. Conversely, 14-3-3ζ deficiency enhanced cutaneous SCC size. Significantly, inhibiting 14-3-3ζ with a novel pharmacological agent accelerated wound healing 2-fold. Patient s les of chronic non-healing wounds overexpressed 14-3-3ζ, while cutaneous SCCs had reduced 14-3-3ζ. These results reveal a novel 14-3-3ζ-dependent mechanism that negatively regulates mechano-reciprocity, suggesting new therapeutic opportunities.
Publisher: Springer Science and Business Media LLC
Date: 10-12-2015
DOI: 10.1038/NCOMMS10169
Abstract: Subtropical and tropical forests are bio ersity hotspots, and untangling the spatial scaling of their ersity is fundamental for understanding global species richness and conserving bio ersity essential to human well-being. However, scale-dependent ersity distributions among coexisting taxa remain poorly understood for heterogeneous environments in bio erse regions. We show that ersity relations among 43 taxa—including plants, arthropods and microorganisms—in a mountainous subtropical forest are highly nonlinear across spatial scales. Taxon-specific differences in β- ersity cause under- or overestimation of overall ersity by up to 50% when using surrogate taxa such as plants. Similar relationships may apply to half of all (sub)tropical forests—including major bio ersity hotspots—where high environmental heterogeneity causes high bio ersity and species turnover. Our study highlights that our general understanding of bio ersity patterns has to be improved—and that much larger areas will be required than in better-studied lowland forests—to reliably estimate bio ersity distributions and devise conservation strategies for the world’s bio erse regions.
Publisher: Elsevier BV
Date: 09-1997
DOI: 10.1016/S0950-3536(97)80023-6
Abstract: Cytokine receptors are members of a erse family of proteins that serve the dual function of recognizing their cognate ligands among a plethora of other factors and of initiating a series of cellular signals that ultimately lead to multiple cellular functions. Although cytokine receptors are only activated by their specific cytokines, some functional overlap occurs as a result of receptor subunit promiscuity, kinase recruitment and the activation of coincident signalling pathways. Knock-out experiments are extremely useful in helping to elucidate functionally relevant interactions between cytokine receptor activation, signalling molecules and cellular function. Defects in cytokine receptors or activation, signalling molecules continue to be identified as the underlying cause of clinical conditions. We discuss newly recognized clinical syndromes and recent research into the molecular basis of cytokine receptor activation that provides new insights into the role of cytokine receptors in normal physiology and disease.
Publisher: Elsevier BV
Date: 08-2008
DOI: 10.1016/J.CELL.2008.05.053
Abstract: Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pleiotropic cytokine that controls the production and function of blood cells, is deregulated in clinical conditions such as rheumatoid arthritis and leukemia, yet offers therapeutic value for other diseases. Its receptors are heterodimers consisting of a ligand-specific alpha subunit and a betac subunit that is shared with the interleukin (IL)-3 and IL-5 receptors. How signaling is initiated remains an enigma. We report here the crystal structure of the human GM-CSF/GM-CSF receptor ternary complex and its assembly into an unexpected dodecamer or higher-order complex. Importantly, mutagenesis of the GM-CSF receptor at the dodecamer interface and functional studies reveal that dodecamer formation is required for receptor activation and signaling. This unusual form of receptor assembly likely applies also to IL-3 and IL-5 receptors, providing a structural basis for understanding their mechanism of activation and for the development of therapeutics.
Publisher: The Company of Biologists
Date: 07-2011
DOI: 10.1242/JCS.080598
Abstract: The secretion of anti-microbial peptides is recognised as an essential step in innate immunity, but there is limited knowledge of the molecular mechanism controlling the release of these effectors from immune response cells. Here, we report that Drosophila 14-3-3ε mutants exhibit reduced survival when infected with either Gram-positive or Gram-negative bacteria, indicating a functional role for 14-3-3ε in innate immunity. In 14-3-3ε mutants, there was a reduced release of the anti-microbial peptide Drosomycin into the haemolymph, which correlated with an accumulation of Drosomycin-containing vesicles near the plasma membrane of cells isolated from immune response tissues. Drosomycin appeared to be delivered towards the plasma membrane in Rab4- and Rab11-positive vesicles and smaller Rab11-positive vesicles. RNAi silencing of Rab11 and Rab4 significantly blocked the anterograde delivery of Drosomycin from the perinuclear region to the plasma membrane. However, in 14-3-3ε mutants there was an accumulation of small Rab11-positive vesicles near the plasma membrane. This vesicular phenotype was similar to that observed in response to the depletion of the vesicular Syntaxin protein Syx1a. In wild-type Drosophila immune tissue, 14-3-3ε was detected adjacent to Rab11, and partially overlapping with Syx1a, on vesicles near the plasma membrane. We conclude that 14-3-3ε is required for Rab11-positive vesicle function, which in turn enables antimicrobial peptide secretion during an innate immune response.
Publisher: Elsevier BV
Date: 02-2001
Publisher: Oxford University Press (OUP)
Date: 1987
Abstract: Upstream sequences of the Klebsiella pneumoniae nifH promoter were mutagenised and activation of the mutated promoters by the nif-specific transcriptional activator protein NifA examined in vivo. Of the sixteen mutations analysed, only those within the nifH upstream activator sequence (UAS), characterised by a TGT-N10-ACA motif, influenced nifH promoter activity. Mutations altering the two-fold rotational symmetry of the UAS or the spacing between the TGT and ACA motifs reduced promoter activity, consistent with the UAS functioning as a NifA binding site. The bases flanking the TGT-ACA motif of the UAS also appear to influence activation by NifA. Substituting the nifH UAS with a binding site for the transcriptional activator NtrC resulted in improved NtrC-dependent activation of the nifH promoter demonstrating that the activator specificity of the nifH promoter is dependent upon the presence of the appropriate upstream sequences to which the activator binds.
Publisher: Elsevier BV
Date: 10-1996
Publisher: Elsevier BV
Date: 04-1997
Publisher: Springer Science and Business Media LLC
Date: 03-12-2013
DOI: 10.1038/TP.2013.99
Publisher: Proceedings of the National Academy of Sciences
Date: 21-06-1994
Abstract: Human granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pleiotropic hemopoietic growth factor and activator of mature myeloid cell function. We have previously shown that residue 21 in the first helix of GM-CSF plays a critical role in both biological activity and high-affinity receptor binding. We have now generated analogues of GM-CSF mutated at residue 21, expressed them in Escherichia coli, and examined them for binding, agonistic, and antagonistic activities. Binding experiments showed that GM E21A, E21Q, E21F, E21H, E21R, and E21K bound to the GM-CSF receptor alpha chain with a similar affinity to wild-type GM-CSF and had lost high-affinity binding to the GM-CSF receptor alpha-chain-common beta-chain complex. From these mutants, only the charge reversal mutants E21R and E21K were completely devoid of agonistic activity. Significantly we found that E21R and E21K antagonized the proliferative effect of GM-CSF on the erythroleukemic cell line TF-1 and primary acute myeloid leukemias, as well as GM-CSF-mediated stimulation of neutrophil superoxide production. This antagonism was specific for GM-CSF in that no antagonism of interleukin 3-mediated TF-1 cell proliferation or tumor necrosis factor alpha-mediated stimulation of neutrophil superoxide production was observed. E. coli-derived GM E21R and E21K were effective antagonists of both nonglycosylated and glycosylated wild-type GM-CSF. These results show that low-affinity GM-CSF binding can be dissociated from receptor activation and have potential clinical significance for the management of inflammatory diseases and certain leukemias where GM-CSF plays a pathogenic role.
Publisher: Portland Press Ltd.
Date: 13-07-2011
DOI: 10.1042/BJ20102178
Abstract: Intracellular 14-3-3 proteins bind to many proteins, via a specific phosphoserine motif, regulating erse cellular tasks including cell signalling and disease progression. The 14-3-3ζ isoform is a molecular chaperone, preventing the stress-induced aggregation of target proteins in a manner comparable with that of the unrelated sHsps (small heat-shock proteins). 1H-NMR spectroscopy revealed the presence of a flexible and unstructured C-terminal extension, 12 amino acids in length, which protrudes from the domain core of 14-3-3ζ and is similar in structure and length to the C-terminal extension of mammalian sHsps. The extension stabilizes 14-3-3ζ, but has no direct role in chaperone action. Lys49 is an important functional residue within the ligand-binding groove of 14-3-3ζ with K49E 14-3-3ζ exhibiting markedly reduced binding to phosphorylated and non-phosphorylated ligands. The R18 peptide binds to the binding groove of 14-3-3ζ with high affinity and also reduces the interaction of 14-3-3ζ ligands. However, neither the K49E mutation nor the presence of the R18 peptide affected the chaperone activity of 14-3-3ζ, implying that the C-terminal extension and binding groove of 14-3-3ζ do not mediate interaction with target proteins during chaperone action. Other region(s) in 14-3-3ζ are most likely to be involved, i.e. the protein's chaperone and phosphoserine-binding activities are functionally and structurally separated.
Publisher: Wiley
Date: 06-11-2017
DOI: 10.1002/ECE3.3488
No related grants have been discovered for Joanna Woodcock.