ORCID Profile
0000-0001-6060-7048
Current Organisations
King's College London
,
Medical University of Vienna
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Proteins and Peptides | Basic Pharmacology | Medicinal and Biomolecular Chemistry | Invertebrate Biology
Flora, Fauna and Biodiversity of environments not elsewhere classified | Expanding Knowledge in the Chemical Sciences | Expanding Knowledge in the Biological Sciences |
Publisher: Elsevier
Date: 2020
Publisher: Elsevier BV
Date: 05-2019
Publisher: Cold Spring Harbor Laboratory
Date: 03-11-2022
DOI: 10.1101/2022.11.02.514707
Abstract: Neuropeptides are important regulators of animal physiology and behavior. Hitherto large-scale localization of neuropeptides mainly relied on immunohistochemical methods requiring the availability of antibody panels, while another limiting factor has been the brain’s opacity for subsequent light or fluorescence microscopy. To address these limitations, we integrated high-resolution mass spectrometry imaging (MSI) with microtomography for a multiplexed mapping of neuropeptides in two evolutionary distant ant species, Atta sexdens and Lasius niger . For analyzing the spatial distribution of chemically erse peptide molecules across the brain in each species, the acquisition of serial mass spectrometry images was essential. As a result, we have comparatively mapped the 3D distributions of eight conserved neuropeptides throughout the brain micro-anatomy. We demonstrate that integrating the 3D MSI data into high-resolution anatomy models can be critical for studying organs with high plasticity such as brains of social insects. Several peptides, like the tachykinin-related peptides TK1 and TK4, were widely distributed in many brain areas of both ant species, whereas others, for instance myosuppressin was restricted to specific regions only. Also, we detected differences at the species level many peptides were identified in the optic lobe of L. niger , but only one peptide (ITG-like) was found in this region in A. sexdens . Our approach provides the basis for investigating fundamental neurobiological processes by visualizing the unbiased 3D neurochemistry in its complex anatomic environment. Until recently, the inability to detect entire molecules such as neuropeptides within their spatial biological context and simultaneously link their occurrence to anatomically and physiologically relevant areas has limited our understanding of complex neurochemical processes. This situation has now changed dramatically with the optimization of a new multiplexed imaging method based on mass spectrometry, which enables us to study previously invisible processes at the microscopic scale. With the marriage of mass spectrometry imaging and microtomography, we show that it has become possible to build high-resolution maps of neuropeptides in complex anatomical structures as small as ant brains. These maps, embedded in the 3D neuroanatomy, expand the understanding of the spatial organization of brain chemistry and provide a baseline for neurobiological and neurochemical studies.
Publisher: Elsevier BV
Date: 03-2016
Abstract: Cyclotides are an interesting family of circular plant peptides. Their unique three-dimensional structure, comprising a head-to-tail circular backbone chain and three disulfide bonds, confers them stability against thermal, chemical, and enzymatic degradation. Their unique stability under extreme conditions creates an idea about the possibility of using harsh extraction methods such as microwave-assisted extraction (MAE) without affecting their structures. MAE has been introduced as a potent extraction method for extraction of natural compounds, but it is seldom used for peptide and protein extraction. In this work, microwave irradiation was applied to the extraction of cyclotides. The procedure was performed in various steps using a microwave instrument under different conditions. High-performance liquid chromatography (HPLC) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) results show stability of cyclotide structures on microwave radiation. The influential parameters, including time, temperature, and the ratio of solvents that are affecting the MAE potency, were optimized. Optimal conditions were obtained at 20 min of irradiation time, 1200 W of system power in 60 °C, and methanol/water at the ratio of 90:10 (v/v) as solvent. The comparison of MAE results with maceration extraction shows that there are similarities between cyclotide sequences and extraction yields.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-12-2017
DOI: 10.1126/SCISIGNAL.AAN3398
Abstract: An oxytocin derivative that may not trigger adverse side effects has been generated.
Publisher: Elsevier BV
Date: 08-2006
DOI: 10.1016/J.TIBS.2006.06.001
Abstract: Cellular functions hinge on the ability of proteins to adopt their correct folds, and misfolded proteins can lead to disease. Here, we focus on the proteins that catalyze disulfide bond formation, a step in the oxidative folding pathway that takes place in specialized cellular compartments. In the endoplasmic reticulum of eukaryotes, disulfide formation is catalyzed by protein disulfide isomerase (PDI) by contrast, prokaryotes produce a family of disulfide bond (Dsb) proteins, which together achieve an equivalent outcome in the bacterial periplasm. The recent crystal structure of yeast PDI has increased our understanding of the function and mechanism of PDI. Comparison of the structure of yeast PDI with those of bacterial DsbC and DsbG reveals some similarities but also striking differences that suggest directions for future research aimed at unraveling the catalytic mechanism of disulfide bond formation in the cell.
Publisher: Elsevier BV
Date: 03-2007
DOI: 10.1016/J.TOXICON.2006.11.018
Abstract: Cyclotides are small disulphide-rich peptides found in plants from the violet (Violaceae), coffee (Rubiaceae) and cucurbit (Cucurbitaceae) families. They have the distinguishing structural features of a macrocyclic peptide backbone and a cystine knot made up of six conserved cysteine residues, which makes cyclotides exceptionally stable. In idual plants express a suite of cyclotides in a wide range of tissue types, including leaves, flowers, stems and roots and it is thought that their natural function in plants is as defence agents. This proposal is supported by their high expression levels in plants and their toxic and growth retardant activity in feeding trials against Helicoverpa spp. insect pests. This review describes the structures and activities of cyclotides with specific reference to their insecticidal activity and compares them with structurally similar cystine knot proteins from peas (Pisum sativum) and an amaranthus crop plant (Amaranthus hypocondriancus). More broadly, cystine knot proteins are common in a wide range of organisms from fungi to mammals, and it appears that this interesting structural motif has evolved independently in different organisms as a stable protein framework that has a variety of biological functions.
Publisher: MDPI AG
Date: 16-09-2020
DOI: 10.3390/BIOM10091326
Abstract: The plant Citrullus colocynthis, a member of the squash (Cucurbitaceae) family, has a long history in traditional medicine. Based on the ancient knowledge about the healing properties of herbal preparations, plant-derived small molecules, e.g., salicylic acid, or quinine, have been integral to modern drug discovery. Additionally, many plant families, such as Cucurbitaceae, are known as a rich source for cysteine-rich peptides, which are gaining importance as valuable pharmaceuticals. In this study, we characterized the C. colocynthis peptidome using chemical modification of cysteine residues, and mass shift analysis via matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry. We identified the presence of at least 23 cysteine-rich peptides in this plant, and eight novel peptides, named citcol-1 to -8, with a molecular weight between ~3650 and 4160 Da, were purified using reversed-phase high performance liquid chromatography (HPLC), and their amino acid sequences were determined by de novo assignment of b- and y-ion series of proteolytic peptide fragments. In silico analysis of citcol peptides revealed a high sequence similarity to trypsin inhibitor peptides from Cucumis sativus, Momordica cochinchinensis, Momordica macrophylla and Momordica sphaeroidea. Using genome/transcriptome mining it was possible to identify precursor sequences of this peptide family in related Cucurbitaceae species that cluster into trypsin inhibitor and antimicrobial peptides. Based on our analysis, the presence or absence of a crucial Arg/Lys residue at the putative P1 position may be used to classify these common cysteine-rich peptides by functional properties. Despite sequence homology and the common classification into the inhibitor cysteine knot family, these peptides appear to have erse and additional bioactivities yet to be revealed.
Publisher: Proceedings of the National Academy of Sciences
Date: 28-03-2016
Abstract: Multiple sclerosis (MS) imposes substantial economic burdens on patients, their families, and society. Until now, there are few therapies available, but often unattractive parenteral application or severe side effects are serious issues. This study highlights the use of circular peptides as orally active T-cell-specific immunosuppressive therapeutics against the MS model experimental autoimmune encephalomyelitis, without inducing major adverse effects. Our work provides a proof of principle that nature-derived cyclic peptides serve as oral active therapeutics, utilizing their intrinsic bioactivity and stable three-dimensional structure. Cyclotides are considered a combinatorial peptide library and they can be anticipated to complement the existing collections of natural products that are used in drug discovery.
Publisher: Springer Science and Business Media LLC
Date: 05-09-2007
DOI: 10.1007/S00253-007-1159-6
Abstract: Cyclotides, a family of disulfide-rich mini-proteins, show a wide range of biological activities, making them interesting targets for pharmaceutical and agrochemical applications, but little is known about their natural function and the events that trigger their expression. An investigation of nutritional variations and irradiation during a batch process involving plant cell cultures has been performed, using the native African medical herb, Oldenlandia affinis, as a model plant. The results demonstrated the biosynthesis of kalata B1, the main cyclotide in O. affinis, in a combined growth/nongrowth-associated pattern. The highest concentration, 0.37 mg g(-1) dry weight, was accumulated in irradiated cells at 35 mumol m(-2) s(-1). Furthermore, 12 novel cyclotides were identified and the expression of various cyclotides compared in irradiated vs non-irradiated cultures. The results indicate that cyclotide expression varies greatly depending on physiological conditions and environmental stress. Kalata B1 is the most abundant cyclotide in plant suspension cultures, which underlies its importance as a natural defense molecule. The identification of novel cyclotides in suspension cultures, compared to whole plants, indicates that there may be more novel cyclotides to be discovered and that the genetic network regulating cyclotide expression is a very sensitive system, ready to adapt to the current environmental growth condition.
Publisher: American Chemical Society (ACS)
Date: 30-09-2021
Publisher: Public Library of Science (PLoS)
Date: 26-06-2013
Publisher: American Chemical Society (ACS)
Date: 25-03-2016
Publisher: Elsevier BV
Date: 2014
Publisher: Wiley
Date: 2010
DOI: 10.1002/BIP.21414
Publisher: American Chemical Society (ACS)
Date: 20-02-2015
DOI: 10.1021/NP5007668
Abstract: A new orbitide named ribifolin was isolated and characterized from Jatropha ribifolia using mass spectrometry, NMR spectroscopy, quantitative amino acid analysis, molecular dynamics/simulated annealing, and Raman optical activity measurements and calculations. Ribifolin (1) and its linear form (1a) were synthesized by solid-phase peptide synthesis, followed by evaluation of its antiplasmodial and cytotoxicity activities. Compound 1 was moderately effective (IC50 = 42 μM) against the Plasmodium falciparum strain 3D7.
Publisher: Elsevier BV
Date: 09-2019
Publisher: Georg Thieme Verlag KG
Date: 15-09-2010
Publisher: Bentham Science Publishers Ltd.
Date: 09-2010
Publisher: Wiley
Date: 19-06-2012
Publisher: Springer Science and Business Media LLC
Date: 02-2017
DOI: 10.1038/SREP41002
Abstract: Characterisation of G protein-coupled receptors (GPCR) relies on the availability of a toolbox of ligands that selectively modulate different functional states of the receptors. To uncover such molecules, we explored a unique strategy for ligand discovery that takes advantage of the evolutionary conservation of the 600-million-year-old oxytocin/vasopressin signalling system. We isolated the insect oxytocin/vasopressin orthologue inotocin from the black garden ant ( Lasius niger ), identified and cloned its cognate receptor and determined its pharmacological properties on the insect and human oxytocin/vasopressin receptors. Subsequently, we identified a functional dichotomy: inotocin activated the insect inotocin and the human vasopressin V 1b receptors, but inhibited the human V 1a R. Replacement of Arg8 of inotocin by D-Arg8 led to a potent, stable and competitive V 1a R-antagonist ([D-Arg8]-inotocin) with a 3,000-fold binding selectivity for the human V 1a R over the other three subtypes, OTR, V 1b R and V 2 R. The Arg8/D-Arg8 ligand-pair was further investigated to gain novel insights into the oxytocin/vasopressin peptide-receptor interaction, which led to the identification of key residues of the receptors that are important for ligand functionality and selectivity. These observations could play an important role for development of oxytocin/vasopressin receptor modulators that would enable clear distinction of the physiological and pathological responses of the in idual receptor subtypes.
Publisher: Springer Science and Business Media LLC
Date: 28-03-2009
Abstract: Streptococcus equi subsp. zooepidemicus ( S. zooepidemicus ) is a commensal of horses and an opportunistic pathogen in many animals and humans. Some strains produce copious amounts of hyaluronic acid, making S. zooepidemicus an important industrial microorganism for the production of this valuable biopolymer used in the pharmaceutical and cosmetic industry. Encapsulation by hyaluronic acid is considered an important virulence factor in other streptococci, though the importance in S. zooepidemicus remains poorly understood. Proteomics may provide a better understanding of virulence factors in S. zooepidemicus , facilitate the design of better diagnostics and treatments, and guide engineering of superior production strains. Using hyaluronidase to remove the capsule and by optimising cellular lysis, a reference map for S. zooepidemicus was completed. This protocol significantly increased protein recovery, allowing for visualisation of 682 spots and the identification of 86 proteins using mass spectrometry (LC-ESI-MS/MS and MALDI-TOF/TOF) of which 16 were membrane proteins. The data presented constitute the first reference map for S. zooepidemicus and provide new information on the identity and characteristics of the more abundantly expressed proteins.
Publisher: Springer Science and Business Media LLC
Date: 11-2014
Publisher: Elsevier BV
Date: 05-2012
Publisher: Cold Spring Harbor Laboratory
Date: 28-06-2022
DOI: 10.1101/2022.06.27.497311
Abstract: Research continues to identify genetic variation, environmental exposures, and their mixtures underlying different diseases and conditions. There is a need for screening methods to understand the molecular outcomes of such factors. Here, we investigate a highly efficient and multiplexable, fractional factorial experimental design (FFED) to study six environmental factors and four human induced pluripotent stem cell line derived differentiating human neural progenitors. We showcase the FFED coupled with RNA-sequencing to identify the effects of low-grade exposures to these environmental factors and analyse the results in the context of autism spectrum disorder (ASD). We performed this after five-day exposures on differentiating human neural progenitors accompanied by a layered analytical approach and detected several convergent and ergent, gene and pathway level responses. We revealed significant upregulation of pathways related to synaptic function and lipid metabolism following lead and fluoxetine exposure, respectively. The lipid changes were validated using mass spectrometry- based metabolomics after fluoxetine exposure. Our study demonstrates that the FFED can be used for multiplexed transcriptomic analyses to detect relevant pathway-level changes in human neural development caused by low-grade environmental risk factors. Future studies will require multiple cell lines with different genetic backgrounds for characterising the effects of environmental exposures in ASD.
Publisher: American Chemical Society (ACS)
Date: 26-07-2021
Publisher: Elsevier BV
Date: 03-2016
DOI: 10.1016/J.FITOTE.2015.12.021
Abstract: Cyclotides describe a unique cyclic peptide family that displays a broad range of biological activities including uterotonic, anti-bacteria, anti-cancer and anti-HIV. The vigno cyclotides consist of vigno 1-10 were reported recently from Viola ignobilis. In the present study, we examined the effects of vigno 5, a natural cyclopeptide from V. ignobilis, on cervical cancer cells and the underlying mechanisms. We found that vigno 5-treated Hela cells were killed off by apoptosis in a dose-dependent manner within 24h, and were characterized by the appearance of nuclear shrinkage, cleavage of poly (ADP-ribose) polymerase (PARP) and DNA fragmentation. The mitochondrial pathway of apoptosis revealed that cytochrome C is released from mitochondria to cytosol, associated with the activation of caspase-9 and -3, and the cleavage of poly (ADP-ribose) polymerase (PARP). Overall, the results indicate that vigno 5 induces apoptosis in part via the mitochondrial pathway, which is associated with a release of cytochrome C and elevated activity of caspase-9 and -3 in Hela cells.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0SC05501H
Abstract: Structural and pharmacological study of parallel, antiparallel and N- to C-terminal cyclized homo- and heterodimers of vasopressin and oxytocin. This study spotlights dimerization as a strategy to modulate the pharmacology of neuropeptides.
Publisher: Elsevier BV
Date: 12-2012
Publisher: Elsevier BV
Date: 07-2007
Publisher: Elsevier BV
Date: 07-2015
Publisher: Springer New York
Date: 2009
Publisher: Springer Science and Business Media LLC
Date: 14-08-2012
Publisher: Mary Ann Liebert Inc
Date: 2008
Abstract: Cyclic cystine knot proteins are small but topologically complex molecules that occur naturally in plants and have a wide range of bioactivities that make them interesting from a pharmaceutical perspective. Their remarkable stability is dependent on the correct formation of a knotted arrangement of disulfide bonds. This review reports on studies that have deciphered the pathways to the "tying of the knot." These studies have involved a range of biophysical techniques and suggest that the major intermediate species presented on these pathways are two disulfide native species, which are not necessarily the precursors of the native protein. Structural elucidations of one analogue and one such intermediate have been reported, and they both show highly native-like conformation and native disulfide bond connectivity. Cyclic cystine knot formation has also been shown to be assisted by protein disulfide isomerase. The points summarized in this review will be important to consider in the design of novel pharmaceutically interesting biomolecules based on the cyclic cystine knot motif, which has shown potential as a molecular scaffold because of its exceptional stability.
Publisher: American Chemical Society (ACS)
Date: 11-2021
Publisher: American Chemical Society (ACS)
Date: 24-01-2012
DOI: 10.1021/NP200722W
Publisher: Wiley
Date: 09-2013
DOI: 10.1002/BIP.22258
Abstract: Cyclotides are a large family of plant peptides characterized by their cyclic cystine knot composed of a circular backbone and three disulfide bonds that impart exceptional stability. They, and several acyclic variants, have been isolated from plants within the Rubiaceae, Violaceae, Cucurbitaceae, Fabaceae, Solanaceae, and Poaceae families. A variety of chemical and genetic approaches have been applied for the discovery and characterization of cyclotides. As investigations of cyclotide expression, distribution, and phylogeny rapidly increase, the authors have proposed the inclusion of information pertaining to plant species that have been analyzed but do not appear to express cyclotides into the CyBase database. CyBase is dedicated to providing web tools and information about cyclic peptides and proteins to the scientific community. Including detailed information about s ling and analysis parameters of plant species that have been investigated but not published elsewhere should assist in the process of selecting species for establishing new cyclotide discovery projects, as well as for detailed reanalysis using alternative technical approaches. In summary, the collection and deposition of all plant species that have been examined (whether cyclotides have been found or not) would help to impart a deeper understanding of cyclotide discovery, evolution, and physiological function. © 2013 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 100: 433–437, 2013.
Publisher: Springer Science and Business Media LLC
Date: 05-04-2019
Publisher: Elsevier BV
Date: 05-2014
Publisher: Elsevier
Date: 2015
Publisher: Informa UK Limited
Date: 21-09-2023
Publisher: Portland Press Ltd.
Date: 23-03-2021
DOI: 10.1042/BCJ20201005
Abstract: Bowman–Birk inhibitors (BBIs) are plant-derived serine proteinase inhibitors. Endogenously, they function as defense molecules against pathogens and insects, but they also have been explored for applications in cancer treatment and inflammatory disorders. Here, we isolated 15 novel BBIs from the bulb of Hyacinthus orientalis (termed HOSPIs). These isoinhibitors consisted of two or three chains, respectively, that are linked by disulfides bonds based on proposed cleavage sites in the canonical BBI reactive site loop. They strongly inhibited trypsin (Ki = 0.22–167 nM) and α-chymotrypsin (Ki = 19–1200 nM). Notably, HOSPI-B4 contains a six-residue reactive loop, which appears to be the smallest such motif discovered in BBIs to date. HOSPI-A6 and -A7 contain an unusual reactive site, i.e. Leu–Met at the P1–P1′ position and have strong inhibitory activity against trypsin, α-chymotrypsin, and elastase. Analysis of the cDNA encoding HOSPIs revealed that the precursors have HOSPI-like domains repeated at least twice with a defined linker sequence connecting in idual domains. Lastly, mutational analysis of HOSPIs suggested that the linker sequence does not affect the inhibitory activity, and a Thr residue at the P2 site and a Pro at the P3′ site are crucial for elastase inhibition. Using mammalian proteases as representative model system, we gain novel insight into the sequence ersity and proteolytic activity of plant BBI. These results may aid the rational design of BBI peptides with potent and distinct inhibitory activity against human, pathogen, or insect serine proteinases.
Publisher: Portland Press Ltd.
Date: 29-01-2013
DOI: 10.1042/BST20120256
Abstract: The design and development of selective ligands for the human OT (oxytocin) and AVP (arginine vasopressin) receptors is a big challenge since the different receptor subtypes and their native peptide ligands display great similarity. Detailed understanding of the mechanism of OT's interaction with its receptor is important and may assist in the ligand- or structure-based design of selective and potent ligands. In the present article, we compared 69 OT- and OT-like receptor sequences with regards to their molecular evolution and ersity, utilized an in silico approach to map the common ligand interaction sites of recently published G-protein-coupled receptor structures to a model of the human OTR (OT receptor) and compared these interacting residues within a selection of different OTR sequences. Our analysis suggests the existence of a binding site for OT peptides within the common transmembrane core region of the receptor, but it appears extremely difficult to identify receptor or ligand residues that could explain the selectivity of OT to its receptors. We remain confident that the presented evolutionary overview and modelling approach will aid interpretation of forthcoming OTR crystal structures.
Publisher: Elsevier BV
Date: 10-2013
Publisher: Public Library of Science (PLoS)
Date: 20-03-2012
Publisher: Springer Science and Business Media LLC
Date: 13-12-2016
DOI: 10.1038/SREP39177
Abstract: Oxytocin and vasopressin mediate a range of physiological functions that are important for osmoregulation, reproduction, social behaviour, memory and learning. The origin of this signalling system is thought to date back ~600 million years. Oxytocin/vasopressin-like peptides have been identified in several invertebrate species and they appear to be functionally related across the entire animal kingdom. There is little information available about the biology of this peptide G protein-coupled receptor signalling system in insects. Recently over 200 insect genome/transcriptome datasets were released allowing investigation of the molecular structure and phylogenetic distribution of the insect oxytocin/vasopressin orthologue – inotocin peptides and their receptors. The signalling system is present in early arthropods and representatives of some early- erging lineages. However, Trichoptera, Lepidoptera, Siphonaptera, Mecoptera and Diptera, lack the presence of inotocin genes, which suggests the peptide-receptor system was probably lost in their common ancestor ~280 million-years-ago. In addition we detected several losses of the inotocin signalling system in Hemiptera (white flies, scale insects and aphids), and the complete absence in spiders (Chelicerata). This unique insight into evolutionarily patterns and sequence ersity of neuroendocrine hormones will provide opportunities to elucidate the physiology of the inotocin signalling system in one of the largest group of animals.
Publisher: Wiley
Date: 15-07-2010
Publisher: Cold Spring Harbor Laboratory
Date: 26-07-2020
DOI: 10.1101/2020.07.25.221085
Abstract: C-X-C chemokine receptor type 4 (CXCR4) is involved in several intractable disease processes, including HIV infection, cancer cell metastasis, leukemia cell progression, rheumatoid arthritis, asthma and pulmonary fibrosis. Thus, CXCR4 represents a promising drug target and several CXCR4 antagonizing agents are in preclinical or clinical development. Important parameters in drug lead evaluation are determination of binding affinities to the receptor and assessment of their stability and activity in plasma or blood of animals and humans. Here, we designed a microtiter plate-based CXCR4 antibody competition assay that enables to measure inhibitory concentrations (IC 50 values) and affinity constants (K i values) of CXCR4 targeting drugs. The assay is based on the observation that most if not all CXCR4 antagonists compete with binding of the fluorescence-tagged CXCR4 antibody 12G5 to the receptor. We demonstrate that this antibody-competition assay allows a convenient and cheap determination of binding affinities of various CXCR4 antagonists in living cells within just 3 hours. Moreover, the assay can be performed in the presence of high concentrations of physiologically relevant body fluids, and thus is a useful readout to evaluate stability (i.e. half-life) of CXCR4 ligands in serum lasma, and even whole human and mouse blood ex vivo . Thus, this optimized 12G5 antibody competition assay allows a robust and convenient determination and calculation of various important pharmacological parameters of CXCR4 receptor-drug interaction and may not only foster future drug development but also animal welfare by reducing the number of experimental animals.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 14-08-2020
DOI: 10.1161/CIRCRESAHA.119.316151
Abstract: Kidney homeostasis is critically determined by the coordinated activity of the renin-angiotensin system (RAS), including the balanced synthesis of its main effector peptides Ang (angiotensin) II and Ang (1–7). The condition of enzymatic overproduction of Ang II relative to Ang (1–7) is termed RAS dysregulation and leads to cellular signals, which promote hypertension and organ damage, and ultimately progressive kidney failure. ACE2 (angiotensin-converting enzyme 2) and NEP (neprilysin) induce the alternative, and potentially reno-protective axis by enhancing Ang (1–7) production. However, their in idual contribution to baseline RAS balance and whether their activities change in chronic kidney disease (CKD) has not yet been elucidated. To examine whether NEP-mediated Ang (1–7) generation exceeds Ang II formation in the healthy kidney compared with diseased kidney. In this exploratory study, we used liquid chromatography-tandem mass spectrometry to measure Ang II and Ang (1–7) synthesis rates of ACE, chymase and NEP, ACE2, PEP (prolyl-endopeptidase), PCP (prolyl-carboxypeptidase) in kidney biopsy homogenates in 11 healthy living kidney donors, and 12 patients with CKD. The spatial expression of RAS enzymes was determined by immunohistochemistry. Healthy kidneys showed higher NEP-mediated Ang (1–7) synthesis than Ang II formation, thus displaying a strong preference towards the reno-protective alternative RAS axis. In contrast, in CKD kidneys higher levels of Ang II were recorded, which originated from mast cell chymase activity. Ang (1–7) is the dominant RAS peptide in healthy human kidneys with NEP rather than ACE2 being essential for its generation. Severe RAS dysregulation is present in CKD dictated by high chymase-mediated Ang II formation. Kidney RAS enzyme analysis might lead to novel therapeutic approaches for CKD.
Publisher: American Chemical Society (ACS)
Date: 26-09-2023
Publisher: American Chemical Society (ACS)
Date: 29-10-2020
Publisher: American Chemical Society (ACS)
Date: 07-11-2013
DOI: 10.1021/CB400548S
Publisher: The Company of Biologists
Date: 10-10-2023
DOI: 10.1242/BIO.060113
Publisher: Proceedings of the National Academy of Sciences
Date: 18-11-2013
Abstract: G protein-coupled receptors (GPCRs) are promising drug targets: % of the currently marketed drugs elicit their actions by binding to these transmembrane receptors. However, only ∼10% of all GPCRs are targeted by approved drugs. Resorting to plant-derived compounds catalogued by ethnopharmacological analyses may increase this repertoire. We provide a proof of concept by analyzing the uterotonic action of an herbal remedy used in traditional African medicine. We identified cyclic peptides, investigated the molecular mechanisms underlying their uterotonic activity, and report an oxytocic plant peptide that modulates the human oxytocin/vasopressin receptors. This naturally occurring peptide served as a template for the design of an oxytocin-like nonapeptide with enhanced receptor selectivity, highlighting the potential of cyclotides for the discovery of peptide-based GPCR ligands.
Publisher: American Chemical Society (ACS)
Date: 14-05-2018
Publisher: Elsevier BV
Date: 02-2016
Publisher: Cold Spring Harbor Laboratory
Date: 17-09-2022
DOI: 10.1101/2022.09.14.507275
Abstract: Genetic variants affecting Heterogeneous Nuclear Ribonucleoprotein U (HNRNPU) have been identified in several neurodevelopmental disorders (NDDs). HNRNPU is widely expressed in the human brain and shows the highest postnatal expression in the cerebellum. Recent studies have investigated the role of HNRNPU in cerebral cortical development, but the effects of HNRNPU deficiency on cerebellar development remain unknown. Here, we describe the molecular and cellular outcomes of HNRNPU locus deficiency during in vitro neural differentiation of patient-derived and isogenic neuroepithelial stem cells with a hindbrain profile. We demonstrate that HNRNPU deficiency leads to chromatin remodeling of A/B compartments, and transcriptional rewiring, partly by impacting exon inclusion during mRNA processing. Genomic regions affected by the chromatin restructuring and host genes of exon usage differences show a strong enrichment for genes implicated in epilepsies, intellectual disability, and autism. Lastly, we show that at the cellular level. HNRNPU downregulation leads to altered neurogenesis and an increased fraction of neural progenitors in the maturing neuronal population. We conclude that, HNRNPU locus is involved in delayed commitment of neural progenitors to neuronal maturation in cell types with hindbrain profile.
Publisher: Elsevier BV
Date: 08-2012
Publisher: Oxford University Press (OUP)
Date: 25-04-2023
DOI: 10.1093/PNASNEXUS/PGAD144
Abstract: Neuropeptides are important regulators of animal physiology and behavior. Hitherto the gold standard for the localization of neuropeptides have been immunohistochemical methods that require the synthesis of antibody panels, while another limiting factor has been the brain's opacity for subsequent in situ light or fluorescence microscopy. To address these limitations, we explored the integration of high-resolution mass spectrometry imaging (MSI) with microtomography for a multiplexed mapping of neuropeptides in two evolutionary distant ant species, Atta sexdens and Lasius niger. For analyzing the spatial distribution of chemically erse peptide molecules across the brain in each species, the acquisition of serial mass spectrometry images was essential. As a result, we have comparatively mapped the three-dimensional (3D) distributions of eight conserved neuropeptides throughout the brain microanatomy. We demonstrate that integrating the 3D MSI data into high-resolution anatomy models can be critical for studying organs with high plasticity such as brains of social insects. Several peptides, like the tachykinin-related peptides (TK) 1 and 4, were widely distributed in many brain areas of both ant species, whereas others, for instance myosuppressin, were restricted to specific regions only. Also, we detected differences at the species level many peptides were identified in the optic lobe of L. niger, but only one peptide (ITG-like) was found in this region in A. sexdens. Building upon MS imaging studies on neuropeptides in invertebrate model systems, our approach leverages correlative MSI and computed microtomography for investigating fundamental neurobiological processes by visualizing the unbiased 3D neurochemistry in its complex anatomic environment.
Publisher: American Chemical Society (ACS)
Date: 05-01-2021
Publisher: American Chemical Society (ACS)
Date: 26-08-2023
Publisher: Oxford University Press (OUP)
Date: 09-2008
Abstract: Cyclotides are disulfide-rich miniproteins with the unique structural features of a circular backbone and knotted arrangement of three conserved disulfide bonds. Cyclotides have been found only in two plant families: in every analyzed species of the violet family (Violaceae) and in few species of the coffee family (Rubiaceae). In this study, we analyzed & Rubiaceae species and confirmed the presence of cyclotides in 22 species. Additionally, we analyzed & species in related plant families to Rubiaceae and Violaceae and report the occurrence of cyclotides in the Apocynaceae. We further report new cyclotide sequences that provide insights into the mechanistic basis of cyclotide evolution. On the basis of the phylogeny of cyclotide-bearing plants and the analysis of cyclotide precursor gene sequences, we hypothesize that cyclotide evolution occurred independently in various plant families after the ergence of Asterids and Rosids (∼125 million years ago). This is strongly supported by recent findings on the in planta biosynthesis of cyclotides, which involves the serendipitous recruitment of ubiquitous proteolytic enzymes for cyclization. We further predict that the number of cyclotides within the Rubiaceae may exceed tens of thousands, potentially making cyclotides one of the largest protein families in the plant kingdom.
Publisher: Frontiers Media SA
Date: 25-09-2017
Publisher: Wiley
Date: 04-11-2009
DOI: 10.1002/BIP.21113
Abstract: We recently isolated a protein disulfide isomerase (PDI) from the Rubiaceae (coffee family) plant Oldenlandia affinis (OaPDI) and demonstrated that it facilitates the production of disulfide-knotted defense proteins called cyclotides. PDIs are major folding catalysts in the eukaryotic ER where they are responsible for formation, breakage, or shuffling of disulfide bonds in substrate polypeptides and are important chaperones in the secretory pathway. Here, we report the first detailed analysis of the oligomerization behavior of a plant PDI, based on characterization of OaPDI using various biochemical and biophysical techniques, including size-exclusion chromatography, NMR spectroscopy, surface plasmon resonance and atomic force microscopy. In solution at low concentration OaPDI comprises mainly monomers, but fractions of dimers and/or higher-order oligomers were observed at increased conditions, raising the possibility that dimerization and/or oligomerization could be a mechanism to adapt to the various-sized polypeptide substrates of PDI. Unlike mammalian PDIs, oligomerization of the plant PDI is not driven by the formation of intermolecular disulfide bonds, but by noncovalent interactions. The information derived in this study advances our understanding of the oligomerization behavior of OaPDI in particular but is potentially of broader interest for understanding the mechanism and role of oligomerization, and hence the catalytic and physiological mechanism, of the ubiquitous folding catalyst PDI.
Publisher: Frontiers Media SA
Date: 11-10-2017
Publisher: Springer Science and Business Media LLC
Date: 04-2016
Publisher: Wiley
Date: 09-2013
DOI: 10.1002/BIP.22328
Abstract: Cyclotides are a unique class of ribosomally synthesized cysteine‐rich miniproteins characterized by a head‐to‐tail cyclized backbone and three conserved disulfide‐bonds in a knotted arrangement. Originally they were discovered in the coffee‐family plant Oldenlandia affinis (Rubiaceae) and have since been identified in several species of the violet, cucurbit, pea, potato, and grass families. However, the identification of novel cyclotide‐containing plant species still is a major challenge due to the lack of a rapid and accurate analytical workflow in particular for large s ling numbers. As a consequence, their phylogeny in the plant kingdom remains unclear. To gain further insight into the distribution and evolution of plant cyclotides, we analyzed ∼300 species of different families, with special emphasis on plants from the order Gentianales. For this purpose, we have developed a refined screening methodology combining chemical analysis of plant extracts and bioinformatic analysis of transcript databases. Using mass spectrometry and transcriptome‐mining, we identified nine novel cyclotide‐containing species and their related cyclotide precursor genes in the tribe Palicoureeae. The characterization of novel peptide sequences underlines the high variability and plasticity of the cyclotide framework, and a comparison of novel precursor proteins from Carapichea ipecacuanha illustrated their typical cyclotide gene architectures. Phylogenetic analysis of their distribution within the Psychotria alliance revealed cyclotides to be restricted to Palicourea , Margaritopsis , Notopleura , Carapichea , Chassalia , and Geophila . In line with previous reports, our findings confirm cyclotides to be one of the largest peptide families within the plant kingdom and suggest that their total number may exceed tens of thousands. © 2013 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 100: 438–452, 2013.
Publisher: Springer Science and Business Media LLC
Date: 17-12-2019
DOI: 10.1038/S41598-019-55675-W
Abstract: The neuropeptides oxytocin (OT) and vasopressin (VP) and their G protein-coupled receptors OTR, V 1a R, V 1b R, and V 2 R form an important and widely-distributed neuroendocrine signaling system. In mammals, this signaling system regulates water homeostasis, blood pressure, reproduction, as well as social behaviors such as pair bonding, trust and aggression. There exists high demand for ligands with differing pharmacological profiles to study the physiological and pathological functions of the in idual receptor subtypes. Here, we present the pharmacological characterization of an arthropod ( Metaseiulus occidentalis ) OT/VP-like nonapeptide across the human OT/VP receptors. I8-arachnotocin is a full agonist with respect to second messenger signaling at human V 2 R (EC 50 34 nM) and V 1b R (EC 50 1.2 µM), a partial agonist at OTR (EC 50 790 nM), and a competitive antagonist at V 1a R [pA 2 6.25 (558 nM)]. Intriguingly, I8-arachnotocin activated the Gα s pathway of V 2 R without recruiting either β-arrestin-1 or β-arrestin-2. I8-arachnotocin might thus be a novel pharmacological tool to study the (patho)physiological relevance of β-arrestin-1 or -2 recruitment to the V 2 R. These findings furthermore highlight arthropods as a novel, vast and untapped source for the discovery of novel pharmacological probes and potential drug leads targeting neurohormone receptors.
Publisher: Springer Science and Business Media LLC
Date: 30-03-2023
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0CB00062K
Abstract: Cyclotides are plant-derived cyclic peptides that have emerged as promising scaffold molecules for designing peptide-based therapeutics. Cyclotide engineering may lead to the development of novel ligands of G protein-coupled receptors with improved pharmacological properties.
Publisher: Elsevier BV
Date: 09-2014
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3NP90040A
Publisher: Informa UK Limited
Date: 09-11-2013
DOI: 10.4161/CIB.27583
Publisher: Springer Science and Business Media LLC
Date: 03-07-2018
DOI: 10.1038/S41598-018-28380-3
Abstract: The oxytocin/vasopressin signalling system is conserved across the animal kingdom. In insects, the role of oxytocin-type (inotocin) neuropeptides has only been studied in locusts, beetles and ants, but their physiology continues to be poorly understood. One reason for this knowledge deficit is the lack of available research tools to complement functional genomics efforts. Consequently, ligands to probe insect inotocin receptors are essential. In this study, we sought to identify novel agonists and antagonists of the inotocin receptor from the representative model species Tribolium castaneum and Lasius niger . Drawing upon known ligands of the human receptors, we examined the pharmacology of the plant-derived cyclotide kalata B7 and the synthetic oxytocin analogue atosiban. Kalata B7 is a weak partial agonist of both inotocin receptors. This is the first reported direct interaction of cyclotides with an insect receptor, an observation that may explain their presumed role in herbivore defence. Furthermore, we discovered atosiban is an antagonist of the Tribolium receptor, which may provide a useful probe to investigate the functionality of inotocin signalling in beetles and related insect species. Our findings will enable further examination of insect inotocin receptor pharmacology and physiology, and may trigger studies to comprehend the interaction of plant cyclotides and insects.
Publisher: Springer Science and Business Media LLC
Date: 11-08-2020
DOI: 10.1038/S41388-020-01415-8
Abstract: Breast cancer is making up one-quarter of all new female cancer cases diagnosed worldwide. Breast cancer surgeries, radiation therapies, cytotoxic chemotherapies and targeted therapies have made significant progress and play a dominant role in breast cancer patient management. However, many challenges remain, including resistance to systemic therapies, tumour recurrence and metastasis. The cyclic neuropeptide oxytocin (OT) elicits a plethora of biological responses via the oxytocin receptor (OTR) in both the central and peripheral nervous system, including social bonding, stress, maternal behaviour, sexual activity, uterus contraction, milk ejection and cancer. As a typical member of the G protein-coupled receptor family, OTR represents also an intriguing target for cancer therapy. There is emerging evidence that OTR plays a role in breast cancer development and progression, and several breast cancer cell lines express OTR. However, despite supporting evidence that OT lowers breast cancer risks, its mechanistic role in breast cancer development and the related signalling pathways are not fully understood. Here, we review the current knowledge of the OT/OTR signalling system in healthy breast tissue as well as in breast cancer, and discuss OTR as a potential therapeutic target for breast cancer management.
Publisher: Wiley
Date: 25-06-2018
DOI: 10.1096/FJ.201800443
Publisher: American Chemical Society (ACS)
Date: 20-04-2015
DOI: 10.1021/NP501061T
Publisher: Georg Thieme Verlag KG
Date: 25-09-2023
DOI: 10.1055/A-2173-8627
Publisher: Future Science Ltd
Date: 09-2012
DOI: 10.4155/FMC.12.108
Publisher: American Chemical Society (ACS)
Date: 24-06-2021
Publisher: Wiley
Date: 24-09-2021
Publisher: Elsevier BV
Date: 10-2012
DOI: 10.1016/J.JPROT.2012.07.042
Abstract: High biological variation in protein expression represents a major challenge in clinical proteomics. In a study based on 2D-DIGE, we found that the standardised abundance of only a few proteins varied by more than 50%. While some of the highest variable proteins in platelets of 52 healthy elderly were of plasmatic origin, such as albumin or haptoglobin, absence of several other high-abundant plasma proteins strongly suggests that plasma-derived proteins represent an integral part of the platelet proteome. Amongst the highly variable platelet-derived proteins, two spots were both identified as GSTO1 and assigned to either the wild-type or mutant isoform of SNP A140D. Remarkably, when the spots were considered within the respective genotype groups, their CV decreased to about the median variation. Albeit 2D-DIGE allowed correct genotyping, two in iduals seemed to be GSTO1*A140 deficient. Probing 2D-Western blots with novel mAb, however, detected A140 protein as additional spot at pH 8.1, caused by the SNPs E155del and E208K. In contrast to previous studies, we show that GSTO1 protein is expressed in vivo, despite the deletion E155. Our data indicate that incorporation of exogenous proteins and genetic polymorphisms of endogenous proteins represent the main source of extreme biological variation in the platelet proteome.
Publisher: Proceedings of the National Academy of Sciences
Date: 08-03-2016
Abstract: The majority of secreted proteins contain disulfide bonds that provide structural stability in the extracellular environment. The formation of correct disulfide bonds is assisted by the enzyme protein disulfide isomerase (PDI). Most secreted structural domains are ancient and widely distributed in all metazoans in contrast, erse sets of unique disulfide-rich structural domains have more recently evolved in venomous marine snails (superfamily Conoidea comprising ,000 species). We have discovered a previously undescribed gene family encoding PDIs of unprecedented ersity. We suggest that these enzymes constitute an important part of the supporting molecular infrastructure required for properly folding the plethora of structural domains expressed in the venoms of snails in different conoidean lineages.
Publisher: American Chemical Society (ACS)
Date: 08-10-2015
Publisher: Elsevier BV
Date: 07-2011
DOI: 10.1016/J.JEP.2011.05.018
Abstract: Leaf extracts of Betula pendula have been traditionally used for the treatment of patients with rheumatoid arthritis (RA) or osteoarthritis. We investigated the anti-proliferative capacity of an aqueous leaf extract of Betula pendula (BPE) on human primary lymphocytes in vitro, because activated lymphocytes play a major role in the initiation and maintenance of RA. Lymphocyte proliferation and cell ision was measured by the activity of mitochondrial dehydrogenases and by using the membrane-permeable dye carboxyfluorescein diacetate succinimidyl ester (CFSE), respectively. Apoptosis was analyzed by surface staining of phosphatidylserine and intracellular activation of effector caspases 3 and 7 in comparison to the drug methotrexate using flow cytometric and photometrical analysis. In addition, the impact of the extract on cell cycle distribution was investigated by propidium iodide staining of DNA. For the bioassays BPE concentrations of 10-160 μg/mL were investigated. A phytochemical analysis, using LC-MS and HPLC, was conducted to identify the polyphenolic constituents of the birch leaf extract. Leaf extracts of Betula pendula inhibited the growth and cell ision (CD8(+): 40 μg/mL: 45% 80 μg/mL: 60% 160 μg/mL: 87%) (CD4(+): 40 μg/mL: 33% 80 μg/mL: 54% 160 μg/mL: 79%) of activated, but not of resting T lymphocytes in a significant dose-dependent manner. The inhibition of lymphocyte proliferation due to apoptosis induction (compared to untreated control: 40 μg/mL: 163% 80 μg/mL: 240% 160 μg/mL: 348%) and cell cycle arrest was comparable to that of methotrexate. LC-MS analyses showed that the extract contains different quercetin-glycosides. Our results give a rational basis for the use of Betula pendula leaf extract for the treatment of immune disorders, like rheumatoid arthritis, by diminishing proliferating inflammatory lymphocytes.
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 29-10-2014
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2010
End Date: 2013
Funder: FWF Austrian Science Fund
View Funded ActivityStart Date: 2008
End Date: 2010
Funder: FWF Austrian Science Fund
View Funded ActivityStart Date: 2018
End Date: 2018
Funder: Austrian Academic Exchange Service
View Funded ActivityStart Date: 2014
End Date: 2016
Funder: National Research Foundation
View Funded ActivityStart Date: 2013
End Date: 2015
Funder: Grand Challenges Canada
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End Date: 2015
Funder: FWF Austrian Science Fund
View Funded ActivityStart Date: 2017
End Date: 2020
Funder: FWF Austrian Science Fund
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End Date: 2020
Funder: OeAD-GmbH
View Funded ActivityStart Date: 2016
End Date: 2017
Funder: University of Queensland
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End Date: 2018
Funder: Bundesministerium für Wissenschaft, Forschung und Wirtschaft
View Funded ActivityStart Date: 2017
End Date: 2018
Funder: Bundesministerium für Wissenschaft, Forschung und Wirtschaft
View Funded ActivityStart Date: 2014
End Date: 2018
Funder: Vienna Science and Technology Fund
View Funded ActivityStart Date: 2014
End Date: 2015
Funder: Bundesministerium für Wissenschaft, Forschung und Wirtschaft
View Funded ActivityStart Date: 2008
End Date: 2012
Funder: FP7 People: Marie-Curie Actions
View Funded ActivityStart Date: 08-2015
End Date: 02-2018
Amount: $762,602.00
Funder: Australian Research Council
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