ORCID Profile
0000-0001-9165-8526
Current Organisations
St Vincent's Institute of Medical Research
,
Monash University
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Publisher: Cold Spring Harbor Laboratory
Date: 28-09-2022
DOI: 10.1101/2022.09.27.509640
Abstract: Allosteric modulation of G protein-coupled receptors (GPCRs) is a major paradigm in drug discovery. Despite decades of research, a molecular level understanding of the general principals that govern the myriad pharmacological effects exerted by GPCR allosteric modulators remains limited. The M 4 muscarinic acetylcholine receptor (M 4 mAChR) is a well-validated and clinically relevant allosteric drug target for several major psychiatric and cognitive disorders. Here, we present high-resolution cryo-electron microscopy structures of the M 4 mAChR bound to a cognate G i1 protein and the high affinity agonist, iperoxo, in the absence and presence of two different positive allosteric modulators, LY2033298 or VU0467154. We have also determined the structure of the M 4 mAChR-G i1 complex bound to its endogenous agonist, acetylcholine (ACh). Structural comparisons, together with molecular dynamics, mutagenesis, and pharmacological validations, have provided in-depth insights into the role of structure and dynamics in orthosteric and allosteric ligand binding, global mechanisms of receptor activation, cooperativity, probe-dependence, and species variability all key hallmarks underpinning contemporary GPCR drug discovery.
Publisher: American Chemical Society (ACS)
Date: 16-11-2020
Publisher: Wiley
Date: 04-2009
DOI: 10.1111/J.1749-6632.2008.03818.X
Abstract: The relaxin family peptide receptor 3 (RXFP3) is the cognate receptor for the neuropeptide relaxin-3. RXFP3 was tagged at the carboxy-terminus with a variant of the green fluorescent protein (GFP(2)) for use in receptor localization studies. RXFP3-GFP(2) was examined to ensure it retained binding and signaling properties similar to untagged RXFP3. Competition for [(125)I]INSL5/H3 relaxin chimera binding to RXFP3 and RXFP3-GFP(2) indicated that the carboxy-terminal tag did not affect receptor binding or receptor internalization. RXFP3-GFP(2) activated ERK1/2 with a similar potency to RXFP3 when transiently expressed in CHO-K1 or HEK293T cells, suggesting that the GFP(2) tag did not affect receptor function. This study demonstrated that addition of a carboxy-terminal fusion protein to RXFP3 did not alter the binding or signaling properties of RXFP3, making RXFP3-GFP(2) a useful tool for future receptor localization and trafficking studies.
Publisher: Wiley
Date: 05-2022
Publisher: Elsevier BV
Date: 08-2008
DOI: 10.1016/J.DRUDIS.2008.04.002
Abstract: The relaxin family peptides have distinct expression profiles and physiological functions. Several of them are the cognate ligands for 4 G-protein-coupled relaxin family peptide receptors (RXFPs formerly LGR7, LGR8, GPCR135, GPCR142). The relaxin/RXFP1 system has roles in reproductive physiology but is also involved in fibrosis, wound healing and responses to infarction. Relaxin has a potential use in congestive heart failure where fibrosis plays an important role in organ failure. The INSL3/RXFP2 system has biological roles in reproductive biology that may have limited therapeutic potential. However, the recently characterized relaxin-3/RXFP3 system is important in stress/anxiety and body composition. RXFP3 receptor antagonists are potentially novel anti-anxiety and anti-obesity drugs.
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 09-03-2017
Abstract: The
Publisher: Springer Science and Business Media LLC
Date: 16-04-2020
DOI: 10.1038/S41467-020-15945-Y
Abstract: An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Publisher: eLife Sciences Publications, Ltd
Date: 30-05-2023
DOI: 10.7554/ELIFE.83477
Abstract: Allosteric modulation of G protein-coupled receptors (GPCRs) is a major paradigm in drug discovery. Despite decades of research, a molecular-level understanding of the general principles that govern the myriad pharmacological effects exerted by GPCR allosteric modulators remains limited. The M 4 muscarinic acetylcholine receptor (M 4 mAChR) is a validated and clinically relevant allosteric drug target for several major psychiatric and cognitive disorders. In this study, we rigorously quantified the affinity, efficacy, and magnitude of modulation of two different positive allosteric modulators, LY2033298 (LY298) and VU0467154 (VU154), combined with the endogenous agonist acetylcholine (ACh) or the high-affinity agonist iperoxo (Ipx), at the human M 4 mAChR. By determining the cryo-electron microscopy structures of the M 4 mAChR, bound to a cognate G i1 protein and in complex with ACh, Ipx, LY298-Ipx, and VU154-Ipx, and applying molecular dynamics simulations, we determine key molecular mechanisms underlying allosteric pharmacology. In addition to delineating the contribution of spatially distinct binding sites on observed pharmacology, our findings also revealed a vital role for orthosteric and allosteric ligand–receptor–transducer complex stability, mediated by conformational dynamics between these sites, in the ultimate determination of affinity, efficacy, cooperativity, probe dependence, and species variability. There results provide a holistic framework for further GPCR mechanistic studies and can aid in the discovery and design of future allosteric drugs.
Publisher: Wiley
Date: 03-2008
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 23-12-2014
Abstract: The concepts of functional selectivity and ligand bias are becoming increasingly appreciated in modern drug discovery programs, necessitating more informed approaches to compound classification and, ultimately, therapeutic candidate selection. Using the β2-adrenergic receptor as a model, we present a proof of concept study that assessed the bias of 19 β-adrenergic ligands, including many clinically used compounds, across four pathways [cAMP production, extracellular signal-regulated kinase 1/2 (ERK1/2) activation, calcium mobilization, and receptor endocytosis] in the same cell background (human embryonic kidney 293S cells). Efficacy-based clustering placed the ligands into five distinct groups with respect to signaling signatures. In some cases, apparent functional selectivity originated from off-target effects on other endogenously expressed adrenergic receptors, highlighting the importance of thoroughly assessing selectivity of the responses before concluding receptor-specific ligand-biased signaling. Eliminating the nonselective compounds did not change the clustering of the 10 remaining compounds. Some ligands exhibited large differences in potency for the different pathways, suggesting that the nature of the receptor-effector complexes influences the relative affinity of the compounds for specific receptor conformations. Calculation of relative effectiveness (within pathway) and bias factors (between pathways) for each of the compounds, using an operational model of agonism, revealed a global signaling signature for all of the compounds relative to isoproterenol. Most compounds were biased toward ERK1/2 activation over the other pathways, consistent with the notion that many proximal effectors converge on this pathway. Overall, we demonstrate a higher level of ligand texture than previously anticipated, opening perspectives for the establishment of pluridimensional correlations between signaling profiles, drug classification, therapeutic efficacy, and safety.
Publisher: Bentham Science Publishers Ltd.
Date: 2007
DOI: 10.2174/138945007779315650
Abstract: Relaxin was discovered more than 75 years prior to the identification of the receptors that mediate its actions. There has been a slow emergence in understanding the role of relaxin, with it being denoted initially as a hormone of pregnancy due to its observed effects to relax pubic ligaments and soften the cervix of guinea pigs to facilitate parturition. However, many other physiological roles have been identified for relaxin, including cardiovascular and neuropeptide functions and an ability to induce the matrix metalloproteinases, so it is clear that relaxin is not exclusively a hormone of pregnancy but has a much wider role in vivo. The recent de-orphanisation of four receptors LGR7, LGR8, GPCR135 (SALPR) and GPCR142 (GPR100) that respond to and bind at least one of the three forms of relaxin identified to date, allows dissection of this system to determine the precise role of each receptor and enable the identification of new targets for treatment of numerous disease states. Relaxin has the potential to be useful for the treatment of scleroderma, fibrosis, in orthodontics and to facilitate embryo implantation in humans. Relaxin antagonists may act as contraceptives or prevent the development of breast cancer metastases. Recent research has added considerable knowledge to the signalling pathways activated by relaxin, which will aid our understanding of how relaxin produces its effects. The focus of this review is to bring together recent developments in the relaxin receptor field and to highlight their potential as drug targets.
Publisher: American Chemical Society (ACS)
Date: 14-12-2019
DOI: 10.1021/ACSCHEMNEURO.8B00613
Abstract: Targeting allosteric sites of the M
Publisher: Springer Science and Business Media LLC
Date: 30-11-2018
DOI: 10.1038/S41589-018-0182-5
Abstract: In the version of this paper originally published, the structure for epinephrine shown in Figure 1a was redrawn with an extra carbon. The structure has been replaced in the HTML and PDF versions of the article. The original and corrected versions of the structure are shown below.
Publisher: Wiley
Date: 04-12-2022
DOI: 10.1111/BPH.15982
Abstract: Targeting allosteric sites of M 1 muscarinic acetylcholine receptors (M 1 receptors) is a promising strategy to treat neurocognitive disorders, such as Alzheimer's disease and schizophrenia. Indeed, the last two decades have seen an impressive body of work focussing on the design and development of positive allosteric modulators (PAMs) for the M 1 receptor. This has led to the identification of a structurally erse range of highly selective M 1 PAMs. In preclinical models, M 1 PAMs have shown rescue of cognitive deficits and improvement of endpoints predictive of symptom domains of schizophrenia. Yet, to date only a few M 1 PAMs have reached early‐stage clinical trials, with many of them failing to progress further due to on‐target mediated cholinergic adverse effects that have plagued the development of this class of ligand. This review covers the recent preclinical and clinical studies in the field of M 1 receptor drug discovery for the treatment of Alzheimer's disease and schizophrenia, with a specific focus on M 1 PAM, highlighting both the undoubted potential but also key challenges for the successful translation of M 1 PAMs from bench‐side to bedside.
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 24-04-2018
Abstract: Positive allosteric modulators (PAMs) that target the M
Publisher: Public Library of Science (PLoS)
Date: 05-01-2012
Publisher: Wiley
Date: 12-03-2023
DOI: 10.1111/BPH.16057
Abstract: Autism is a neurodevelopmental condition with a range of symptoms that vary in intensity and severity from person to person. Genetic sequencing has identified thousands of genes containing mutations in autistic in iduals, which may contribute to the development of autistic symptoms. Several of these genes encode G protein‐coupled receptors (GPCRs), which are cell surface expressed proteins that transduce extracellular messages to the intracellular space. Mutations in GPCRs can impact their function, resulting in aberrant signalling within cells and across neurotransmitter systems in the brain. This review summarises the current knowledge on autism‐associated single nucleotide variations encoding missense mutations in GPCRs and the impact of these genetic mutations on GPCR function. For some autism‐associated mutations, changes in GPCR expression levels, ligand affinity, potency and efficacy have been observed. However, for many the functional consequences remain unknown. Thus, further work to characterise the functional impacts of the genetically identified mutations is required.
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 09-03-2007
Abstract: Human gene 3 relaxin (H3 relaxin) is a member of the relaxin/insulin family of peptides. Neuropeptides mediate behavioral responses to stress and regulates appetite however, the cell signaling mechanisms that control these events remain to be identified. The relaxin family peptide receptor 3 (RXFP3, formerly GPCR135 or SALPR) was characterized as the receptor for H3 relaxin, functionally coupled to the inhibition of cAMP. We have identified that RXFP3 stably expressed in Chinese hamster ovary (CHO)-K1 (CHO-RXFP3) and human embryonic kidney (HEK) 293 (HEK-RXFP3) cells activates extracellular signal-regulated kinase (ERK) 1/2 when stimulated with H3 relaxin and an H3 relaxin B-chain (dimer) peptide. Using inhibitors of cellular signaling proteins, we subsequently determined the mechanism of ERK1/2 activation by RXFP3. ERK1/2 phosphorylation requires the activation of G(i/o) proteins and seems to require receptor internalization and/or compartmentalization into lipid-rich environments. ERK1/2 activation also predominantly occurred via the activation of a protein kinase C-dependent pathway, although activation of phosphatidylinositol 3-kinase and Src tyrosine kinase were also involved to a lesser extent. The mechanisms underlying ERK1/2 phosphorylation were similar in both CHO-RXFP3 and HEK-RXFP3 cells, although some differences were evident. Phospholipase Cbeta and the transactivation of endogenous epidermal growth factor receptors both played a role in RXFP3-mediated ERK1/2 activation in HEK293 cells however, they were not involved in RXFP3-mediated ERK1/2 activation in the CHO-K1 cell background. The pathways identified in CHO- and HEK-transfected cells were also used in the murine SN56 neuronal cell line, suggesting that these pathways are also important for RXFP3-mediated signaling in the brain.
Publisher: Elsevier
Date: 2011
Publisher: Proceedings of the National Academy of Sciences
Date: 26-11-2019
Abstract: The human M 5 muscarinic acetylcholine receptor (mAChR) has recently emerged as an exciting therapeutic target for treating a range of disorders, including drug addiction. However, a lack of structural information for this receptor subtype has limited further drug development and validation. Here we report a high-resolution crystal structure of the human M 5 mAChR bound to the clinically used inverse agonist, tiotropium. This structure allowed for a comparison across all 5 mAChR family members that revealed important differences in both orthosteric and allosteric sites that could inform the rational design of selective ligands. These structural studies, together with chimeric swaps between the extracellular regions of the M 2 and M 5 mAChRs, provided structural insight into kinetic selectivity, where ligands show differential residency times between related family members. Collectively, our study provides important insights into the nature of orthosteric and allosteric ligand interaction across the mAChR family that could be exploited for the design of selective drugs.
Publisher: Wiley
Date: 04-2009
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 24-11-2009
Abstract: The relaxin family peptide receptors (RXFP) 1 and 2 are targets for the relaxin family peptides relaxin and insulin-like peptide 3 (INSL3), respectively. Although both receptors and peptides share a high degree of sequence identity, the cAMP signaling pathways activated by the two systems are quite distinct. Relaxin activation of RXFP1 initially results in accumulation of cAMP via G(alpha)(s), but this is modulated by inhibition of cAMP through G(alpha)(oB). Over time, RXFP1 recruits coupling to G(alpha)(i3), causing additional cAMP accumulation via a G(alpha)(i3)-Gbetagamma-phosphoinositide 3-kinase (PI3K)-protein kinase C (PKC)zeta pathway. In contrast, INSL3 activation of RXFP2 results in accumulation of cAMP only via G(alpha)(s), modulated by cAMP inhibition through G(alpha)(oB). Thus, the aim of this study was to identify the cause of differential G-protein coupling between these highly similar receptors. Construction of chimeric receptors revealed that G(alpha)(i3) coupling is dependent upon the transmembrane region of RXFP1 and independent of the receptor ectodomain or ligand bound. Generation of C-terminal truncated receptors identified the terminal 10 amino acids of the RXFP1 C terminus as essential for G(alpha)(i3) signaling, and point mutations revealed an obligatory role for Arg(752). RXFP1-mediated G(alpha)(i3), but not G(alpha)(s) or G(alpha)(oB), signaling was also found to be dependent upon membrane rafts, and RXFP1 coupled to G(alpha)(i3) after only 3 min of receptor stimulation. Therefore, RXFP1 coupling to the G(alpha)(i3)-Gbetagamma-PI3K-PKCzeta pathway requires the terminal 10 amino acids of the RXFP1 C terminus and membrane raft localization, and the observed delay in this pathway occurs downstream of G(alpha)(i3).
Publisher: Springer Science and Business Media LLC
Date: 09-09-2019
DOI: 10.1038/S41467-019-11875-6
Abstract: Signaling ersity of G protein-coupled (GPCR) ligands provides novel opportunities to develop more effective, better-tolerated therapeutics. Taking advantage of these opportunities requires identifying which effectors should be specifically activated or avoided so as to promote desired clinical responses and avoid side effects. However, identifying signaling profiles that support desired clinical outcomes remains challenging. This study describes signaling ersity of mu opioid receptor (MOR) ligands in terms of logistic and operational parameters for ten different in vitro readouts. It then uses unsupervised clustering of curve parameters to: classify MOR ligands according to similarities in type and magnitude of response, associate resulting ligand categories with frequency of undesired events reported to the pharmacovigilance program of the Food and Drug Administration and associate signals to side effects. The ability of the classification method to associate specific in vitro signaling profiles to clinically relevant responses was corroborated using β2-adrenergic receptor ligands.
Publisher: Wiley
Date: 03-2007
Publisher: Authorea, Inc.
Date: 28-09-2022
DOI: 10.22541/AU.166439533.37076715/V1
Abstract: Autism is a neurodevelopmental condition with a range of symptoms that vary in intensity and severity from person to person. Genetic sequencing has identified thousands of genes containing mutations in autistic in iduals, which may contribute to the development of autistic symptoms. Several of these genes encode G protein-coupled receptors (GPCRs) which are cell surface expressed proteins that transduce extracellular messages to the intracellular space. Mutations in GPCRs can impact their function, resulting in aberrant signalling within cells, and across neurotransmitter systems in the brain. This review summarises the current knowledge on autism-associated single nucleotide variations encoding missense mutations in GPCRs, and the impact of these genetic mutations on GPCR function. For some autism-associated mutations, changes in GPCR expression levels, ligand affinity, potency and efficacy have been observed however, for many the functional consequences remain unknown. Thus, further work to characterise the functional impacts of the genetically identified mutations is required.
Publisher: Frontiers Media SA
Date: 29-01-2021
DOI: 10.3389/FPHAR.2020.606656
Abstract: The M 1 and M 4 muscarinic acetylcholine receptors (mAChRs) are highly pursued drug targets for neurological diseases, in particular for Alzheimer’s disease and schizophrenia. Due to high sequence homology, selective targeting of any of the M 1 -M 5 mAChRs through the endogenous ligand binding site has been notoriously difficult to achieve. With the discovery of highly subtype selective mAChR positive allosteric modulators in the new millennium, selectivity through targeting an allosteric binding site has opened new avenues for drug discovery programs. However, some hurdles remain to be overcome for these promising new drug candidates to progress into the clinic. One challenge is the potential for on-target side effects, such as for the M 1 mAChR where over-activation of the receptor by orthosteric or allosteric ligands can be detrimental. Therefore, in addition to receptor subtype selectivity, a drug candidate may need to exhibit a biased signaling profile to avoid such on-target adverse effects. Indeed, recent studies in mice suggest that allosteric modulators for the M 1 mAChR that bias signaling toward specific pathways may be therapeutically important. This review brings together details on the signaling pathways activated by the M 1 and M 4 mAChRs, evidence of biased agonism at these receptors, and highlights pathways that may be important for developing new subtype selective allosteric ligands to achieve therapeutic benefit.
Publisher: Elsevier
Date: 2014
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 03-02-2015
Abstract: G protein-coupled receptors (GPCRs) are the largest superfamily of receptors encoded by the human genome, and represent the largest class of current drug targets. Over the last decade and a half, it has become widely accepted that most, if not all, GPCRs possess spatially distinct allosteric sites that can be targeted by exogenous substances to modulate the receptors' biologic state. Although many of these allosteric sites are likely to serve other (e.g., structural) roles, they nonetheless possess appropriate properties to be serendipitously targeted by synthetic molecules. However, there are also ex les of endogenous substances that can act as allosteric modulators of GPCRs. These include not only the obvious ex le, i.e., the G protein, but also a variety of ions, lipids, amino acids, peptides, and accessory proteins that display different degrees of receptor-specific modulatory effects. This also suggests that some GPCRs may possess true "orphan" allosteric sites for hitherto unappreciated endogenous modulators. Of note, the increasing identification of allosteric modulator lipids, inflammatory peptides, and GPCR-targeted autoantibodies indicates that disease context plays an important role in the generation of putative endogenous GPCR modulators. If an endogenous allosteric substance can be shown to play a role in disease, this could also serve as an impetus to pursue synthetic neutral allosteric ligands as novel therapeutic agents.
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 16-02-2010
Abstract: Relaxin family peptide 3 receptors (RXFP3) are activated by H3-relaxin to inhibit forskolin-stimulated cAMP accumulation and stimulate extracellular signal-regulated kinase (ERK) 1/2 phosphorylation. In this study, we sought to identify novel signaling pathways coupled to RXFP3 and to investigate whether other members of the relaxin peptide family activated these pathways. Two patterns of signaling were observed in RXFP3-expressing Chinese hamster ovary (CHO)-K1 and human embryonic kidney (HEK)-293 cells (CHO-RXFP3 and HEK-RXFP3) and murine septal neuron SN56 cell lines: 1) strong inhibition of forskolin-stimulated cAMP accumulation, ERK1/2 activation and nuclear factor (NF)-kappaB reporter gene activation in cells stimulated with H3 relaxin, with weaker activity observed for H2 relaxin, porcine relaxin, or insulin-like peptide (INSL) 3 and 2) strong stimulation of activator protein (AP)-1 reporter genes by H2 relaxin, with weaker activation observed with H3 or porcine relaxin. Two distinct ligand binding sites were identified on RXFP3-expressing cells using two different radioligands. (125)I-INSL5 A-chain/relaxin-3 B-chain chimera bound with high affinity to the RXFP3-expressing cells with competition by H3 relaxin or a H3 relaxin B-chain dimeric peptide, consistent with previous reports. Binding studies with (125)I-H2 relaxin revealed a distinct binding site with potent competition observed with H2 relaxin, H3 relaxin, or INSL3 and weaker competition with porcine relaxin. Thus H3 relaxin potently activates all signaling pathways coupled to RXFP3, whereas H2 relaxin is an AP-1-biased ligand relative to H3 relaxin.
Publisher: Elsevier BV
Date: 2000
Publisher: American Chemical Society (ACS)
Date: 05-04-2022
DOI: 10.1021/ACSCHEMNEURO.1C00827
Abstract: Many Food and Drug Administration (FDA)-approved drugs are structural analogues of the endogenous (natural) ligands of G protein-coupled receptors (GPCRs). However, it is becoming appreciated that chemically distinct ligands can bind to GPCRs in conformations that lead to different cellular signaling events, a phenomenon termed biased agonism. Despite this, the rigorous experimentation and analysis required to identify biased agonism are often not undertaken in most clinical candidates and go unrealized. Recently, xanomeline, a muscarinic acetylcholine receptor (mAChR) agonist, has entered phase III clinical trials for the treatment of schizophrenia. If successful, xanomeline will be the first novel FDA-approved antipsychotic drug in almost 50 years. Intriguingly, xanomeline's potential for biased agonism at the mAChRs and, in particular, the M
Publisher: Elsevier BV
Date: 10-2023
Publisher: American Chemical Society (ACS)
Date: 15-03-2018
DOI: 10.1021/ACS.JMEDCHEM.7B01812
Abstract: Targeting allosteric sites at M
Publisher: Oxford University Press (OUP)
Date: 05-2002
Abstract: Development, growth and function of the ovary are controlled by endocrine and paracrine signals. These may also influence the development of ovarian cancer. The aim of this study was to identify the key molecular markers of the unregulated growth and hormone synthesis seen in ovarian tumours, particularly in granulosa cell tumours (GCT). Genes used in this study were chosen on the basis of our understanding of growth and differentiation in the normal ovary. We sought to define the patterns of gene expression in a panel of epithelial and stromal ovarian tumours. Expression was determined by RT-PCR using gene-specific primers for the FSH receptor (FSHR) the FSH early response genes: regulatory subunit of protein kinase A (RII-beta), cyclin D2 (cycD2) and sgk and late response markers: cyclooxygenase-2 (COX-2) and the LH receptor (LHR). The GCT had high expression of FSHR compared with normal ovaries and the other tumours. cycD2 and RII-beta and COX-2 genes were also highly expressed in the GCT. sgk and LHR expression was lower in all of the tumours than in normal ovaries. Serous cystadenocarcinomas also had an unexpectedly high expression of COX-2. Comparison of the gene expression profiles between each tumour group suggests a molecular phenotype for GCT that is similar to that reported for FSH stimulated pre-ovulatory granulosa cells.
Publisher: Springer Science and Business Media LLC
Date: 16-10-2018
Publisher: The Endocrine Society
Date: 03-2002
Abstract: Granulosa cell tumors of the ovary (GCT) express the inhibin subunit genes and secrete dimeric inhibin. Transgenic mice null for the alpha-inhibin gene develop GCT. It has been suggested that this apparent contradiction may be reconciled if the human GCT are resistant to the tumor-suppressive effects of inhibin. Inhibin receptors have recently been characterized as consisting of either betaglycan or p120 in association with the type II or type I activin receptor subunits (ActR), respectively. To test the hypothesis that GCT may exhibit loss of inhibin receptor expression we have examined the expression of the receptor subunits in a cohort of GCT and in mucinous and serous cystadenocarcinomas and normal ovary. Expression was determined by RT-PCR using gene-specific primers and probes combined with Southern blot analysis of the PCR products. The ActRI subunits and ActRIIA exhibited widespread albeit variable expression across tissues, with the highest levels in the serous tumors. ActRIIB expression was relatively low in the mucinous tumors and high in the GCT. Betaglycan expression was abundant, widespread, and variable across all tissues highest mean levels occurred in the GCT and normal ovary. p120 expression was low or absent in all tissues except the GCT. Within the GCT there was parallel expression of the ActR subunits, betaglycan and p120 the levels, however, varied considerably between tumors. Expression of betaglycan and p120 in most GCT argues against the hypothesis, but does not exclude the possibility that low or absent expression of p120 might be significant in a subset of these tumors.
Publisher: eLife Sciences Publications, Ltd
Date: 11-04-2023
Publisher: American Physiological Society
Date: 2013
DOI: 10.1152/PHYSREV.00001.2012
Abstract: There are seven relaxin family peptides that are all structurally related to insulin. Relaxin has many roles in female and male reproduction, as a neuropeptide in the central nervous system, as a vasodilator and cardiac stimulant in the cardiovascular system, and as an antifibrotic agent. Insulin-like peptide-3 (INSL3) has clearly defined specialist roles in male and female reproduction, relaxin-3 is primarily a neuropeptide involved in stress and metabolic control, and INSL5 is widely distributed particularly in the gastrointestinal tract. Although they are structurally related to insulin, the relaxin family peptides produce their physiological effects by activating a group of four G protein-coupled receptors (GPCRs), relaxin family peptide receptors 1–4 (RXFP1–4). Relaxin and INSL3 are the cognate ligands for RXFP1 and RXFP2, respectively, that are leucine-rich repeat containing GPCRs. RXFP1 activates a wide spectrum of signaling pathways to generate second messengers that include cAMP and nitric oxide, whereas RXFP2 activates a subset of these pathways. Relaxin-3 and INSL5 are the cognate ligands for RXFP3 and RXFP4 that are closely related to small peptide receptors that when activated inhibit cAMP production and activate MAP kinases. Although there are still many unanswered questions regarding the mode of action of relaxin family peptides, it is clear that they have important physiological roles that could be exploited for therapeutic benefit.
Publisher: Wiley
Date: 05-2005
Abstract: This study examined the functional response to human relaxin 2 (H2 relaxin), human relaxin 3 (H3 relaxin), porcine relaxin, and human INSL3 in the cytosensor microphysiometer, using CHO-K1 cells stably expressing human GPCR135. CHO-K1 cells stably expressing GPCR135 were generated by the serial dilution method and receptor properties were assessed. Saturation studies of [125I] H3 relaxin binding to GPCR135 in these cells gave a Bmax of 32.61 +/- 6.5 fmol/mg protein and Kd of 0.12 +/- 0.08 nM. The functional response to H3 relaxin and other relaxin/insulin peptides of GPCR135 expressed in CHO-K1 cells was measured in the cytosensor microphysiometer and analyzed using inhibitors of signal transduction proteins.
Publisher: American Chemical Society (ACS)
Date: 05-08-2021
Start Date: 2008
End Date: 2010
Funder: Canadian Institutes of Health Research
View Funded ActivityStart Date: 2011
End Date: 2019
Funder: National Health and Medical Research Council
View Funded ActivityStart Date: 2008
End Date: 2010
Funder: Fonds de Recherche du Québec - Santé
View Funded ActivityStart Date: 2010
End Date: 2011
Funder: Fonds de Recherche du Québec - Santé
View Funded ActivityStart Date: 2004
End Date: 2008
Funder: National Health and Medical Research Council
View Funded ActivityStart Date: 2008
End Date: 2010
Funder: Heart and Stroke Foundation of Canada
View Funded Activity