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Zhang SS, Larrabee L, Chang AH, Desai S, Sloan L, Wang X, Wu Y, Parvez N, Amaratunga K, Hartman AC, Whitnall A, Mason J, Barton NP, Chu AY, Davitte JM, Csakai AJ, Tibbetts CV, Tolbert AE, O'Keefe H, Polanco J, Foley J, Kmett C, Kehler J, Kozejova G, Wang F, Mayer AP, Koenig P, Foletti D, Pitts SJ, Schnackenberg CG. Discovery of RXFP2 genetic association in resistant hypertensive men and RXFP2 antagonists for the treatment of resistant hypertension. Sci Rep 2024; 14:13209. [PMID: 38851835 PMCID: PMC11162469 DOI: 10.1038/s41598-024-62804-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 05/21/2024] [Indexed: 06/10/2024] Open
Abstract
Hypertension remains a leading cause of cardiovascular and kidney diseases. Failure to control blood pressure with ≥ 3 medications or control requiring ≥ 4 medications is classified as resistant hypertension (rHTN) and new therapies are needed to reduce the resulting increased risk of morbidity and mortality. Here, we report genetic evidence that relaxin family peptide receptor 2 (RXFP2) is associated with rHTN in men, but not in women. This study shows that adrenal gland gene expression of RXFP2 is increased in men with hypertension and the RXFP2 natural ligand, INSL3, increases adrenal steroidogenesis and corticosteroid secretion in human adrenal cells. To address the hypothesis that RXFP2 activation is an important mechanism in rHTN, we discovered and characterized small molecule and monoclonal antibody (mAb) blockers of RXFP2. The novel chemical entities and mAbs show potent, selective inhibition of RXFP2 and reduce aldosterone and cortisol synthesis and release. The RXFP2 mAbs have suitable rat pharmacokinetic profiles to evaluate the role of RXFP2 in the development and maintenance of rHTN. Overall, we identified RXFP2 activity as a potential new mechanism in rHTN and discovered RXFP2 antagonists for the future interrogation of RXFP2 in cardiovascular and renal diseases.
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Affiliation(s)
- Shan-Shan Zhang
- Therapeutics Division, 23andMe, 349 Oyster Point Blvd, South San Francisco, CA, 94080, USA
| | - Lance Larrabee
- Therapeutics Division, 23andMe, 349 Oyster Point Blvd, South San Francisco, CA, 94080, USA
| | - Andrew H Chang
- Therapeutics Division, 23andMe, 349 Oyster Point Blvd, South San Francisco, CA, 94080, USA
| | - Sapna Desai
- Medicinal Science and Technology, GSK, Medicines Research Centre, Gunnels Wood Road, Stevenage, SG1 2NY, UK
| | - Lisa Sloan
- Medicinal Science and Technology, GSK, Medicines Research Centre, Gunnels Wood Road, Stevenage, SG1 2NY, UK
| | - Xin Wang
- Research, 23andMe, 223 N Mathilda Ave., Sunnyvale, CA, 94086, USA
| | - Yixuan Wu
- Therapeutics Division, 23andMe, 349 Oyster Point Blvd, South San Francisco, CA, 94080, USA
| | - Nazia Parvez
- Medicinal Science and Technology, GSK, Medicines Research Centre, Gunnels Wood Road, Stevenage, SG1 2NY, UK
| | - Karen Amaratunga
- Medicinal Science and Technology, GSK, Medicines Research Centre, Gunnels Wood Road, Stevenage, SG1 2NY, UK
| | - Allison C Hartman
- Medicinal Science and Technology, GSK, 1250 S. Collegeville Rd., Collegeville, PA, 19426, USA
| | - Abby Whitnall
- Medicinal Science and Technology, GSK, Medicines Research Centre, Gunnels Wood Road, Stevenage, SG1 2NY, UK
| | - Joseph Mason
- Medicinal Science and Technology, GSK, Medicines Research Centre, Gunnels Wood Road, Stevenage, SG1 2NY, UK
| | - Nicholas P Barton
- Medicinal Science and Technology, GSK, Medicines Research Centre, Gunnels Wood Road, Stevenage, SG1 2NY, UK
| | - Audrey Y Chu
- Genomic Sciences, GSK, 300 Technology Square, Cambridge, MA, 02139, USA
| | | | - Adam J Csakai
- Medicinal Science and Technology, GSK, 200 Cambridgepark Drive, Cambridge, MA, 02140, USA
| | | | - Audrey E Tolbert
- Medicinal Science and Technology, GSK, 200 Cambridgepark Drive, Cambridge, MA, 02140, USA
| | - Heather O'Keefe
- Medicinal Science and Technology, GSK, 200 Cambridgepark Drive, Cambridge, MA, 02140, USA
| | - Jessie Polanco
- Therapeutics Division, 23andMe, 349 Oyster Point Blvd, South San Francisco, CA, 94080, USA
| | - Joseph Foley
- Novel Human Genetics Research Unit, GSK, 1250 S. Collegeville Rd., Collegeville, PA, 19426, USA
| | - Casey Kmett
- DMPK, GSK, 1250 S. Collegeville Rd, Collegeville, PA, 19426, USA
| | - Jonathan Kehler
- Bioanalysis, Immunogenicity and Biomarkers, GSK, 1250 S. Collegeville Rd., Collegeville, PA, 19426, USA
| | - Gabriela Kozejova
- Medicinal Science and Technology, GSK, Medicines Research Centre, Gunnels Wood Road, Stevenage, SG1 2NY, UK
| | - Feng Wang
- DMPK, GSK, 1250 S. Collegeville Rd, Collegeville, PA, 19426, USA
| | - Andrew P Mayer
- Bioanalysis, Immunogenicity and Biomarkers, GSK, 1250 S. Collegeville Rd., Collegeville, PA, 19426, USA
| | - Patrick Koenig
- Therapeutics Division, 23andMe, 349 Oyster Point Blvd, South San Francisco, CA, 94080, USA
| | - Davide Foletti
- Therapeutics Division, 23andMe, 349 Oyster Point Blvd, South San Francisco, CA, 94080, USA
| | - Steven J Pitts
- Research, 23andMe, 223 N Mathilda Ave., Sunnyvale, CA, 94086, USA
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Hossain MA, Bathgate RAD. Challenges in the design of insulin and relaxin/insulin-like peptide mimetics. Bioorg Med Chem 2017; 26:2827-2841. [PMID: 28988628 DOI: 10.1016/j.bmc.2017.09.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/19/2017] [Accepted: 09/19/2017] [Indexed: 12/20/2022]
Abstract
Peptidomimetics are designed to overcome the poor pharmacokinetics and pharmacodynamics associated with the native peptide or protein on which they are based. The design of peptidomimetics starts from developing structure-activity relationships of the native ligand-target pair that identify the key residues that are responsible for the biological effect of the native peptide or protein. Then minimization of the structure and introduction of constraints are applied to create the core active site that can interact with the target with high affinity and selectivity. Developing peptidomimetics is not trivial and often challenging, particularly when peptides' interaction mechanism with their target is complex. This review will discuss the challenges of developing peptidomimetics of therapeutically important insulin superfamily peptides, particularly those which have two chains (A and B) and three disulfide bonds and whose receptors are known, namely insulin, H2 relaxin, H3 relaxin, INSL3 and INSL5.
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Affiliation(s)
- Mohammed Akhter Hossain
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3010, Australia; School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia.
| | - Ross A D Bathgate
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3010, Australia; Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia.
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3
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Patil NA, Rosengren KJ, Separovic F, Wade JD, Bathgate RAD, Hossain MA. Relaxin family peptides: structure-activity relationship studies. Br J Pharmacol 2017; 174:950-961. [PMID: 27922185 DOI: 10.1111/bph.13684] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 11/25/2016] [Accepted: 11/28/2016] [Indexed: 12/21/2022] Open
Abstract
The human relaxin peptide family consists of seven cystine-rich peptides, four of which are known to signal through relaxin family peptide receptors, RXFP1-4. As these peptides play a vital role physiologically and in various diseases, they are of considerable importance for drug discovery and development. Detailed structure-activity relationship (SAR) studies towards understanding the role of important residues in each of these peptides have been reported over the years and utilized for the design of antagonists and minimized agonist variants. This review summarizes the current knowledge of the SAR of human relaxin 2 (H2 relaxin), human relaxin 3 (H3 relaxin), human insulin-like peptide 3 (INSL3) and human insulin-like peptide 5 (INSL5). LINKED ARTICLES This article is part of a themed section on Recent Progress in the Understanding of Relaxin Family Peptides and their Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.10/issuetoc.
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Affiliation(s)
- Nitin A Patil
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia.,School of Chemistry, University of Melbourne, Parkville, VIC, Australia
| | - K Johan Rosengren
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC, Australia
| | - Frances Separovic
- School of Chemistry, University of Melbourne, Parkville, VIC, Australia
| | - John D Wade
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia.,School of Chemistry, University of Melbourne, Parkville, VIC, Australia
| | - Ross A D Bathgate
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia.,Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC, Australia
| | - Mohammed Akhter Hossain
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia.,School of Chemistry, University of Melbourne, Parkville, VIC, Australia
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4
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INSL3 stimulates spermatogonial differentiation in testis of adult zebrafish (Danio rerio). Cell Tissue Res 2015; 363:579-88. [PMID: 26077926 PMCID: PMC4735252 DOI: 10.1007/s00441-015-2213-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 05/08/2015] [Indexed: 01/04/2023]
Abstract
INSL3 (insulin-like peptide 3) is a relaxin peptide family member expressed by Leydig cells in the vertebrate testis. In mammals, INSL3 mediates testicular descent during embryogenesis but information on its function in adults is limited. In fish, the testes remain in the body cavity, although the insl3 gene is still expressed, suggesting yet undiscovered, evolutionary older functions. Anti-Müllerian hormone (Amh), in addition to inhibiting spermatogonial differentiation and androgen release, inhibits the Fsh (follicle-stimulating hormone)-induced increase in insl3 transcript levels in zebrafish testis. Therefore, the two growth factors might have antagonistic effects. We examine human INSL3 (hINSL3) effects on zebrafish germ cell proliferation/differentiation and androgen release by using a testis tissue culture system. hINSL3 increases the proliferation of type A undifferentiated (Aund) but not of type A differentiating (Adiff) spermatogonia, while reducing the proliferation of Sertoli cells associated with proliferating Aund. Since the area occupied by Aund decreases and that of Adiff increases, we conclude that hINSL3 recruits Aund into differentiation; this is supported by the hINSL3-induced down-regulation of nanos2 transcript levels, a marker of single Aund spermatogonia in zebrafish and other vertebrates. Pulse-chase experiments with a mitosis marker also indicate that hINSL3 promotes spermatogonial differentiation. However, hINSL3 does not modulate basal or Fsh-stimulated androgen release or growth factor transcript levels, including those of amh. Thus, hINSL3 seems to recruit Aund spermatogonia into differentiation, potentially mediating an Fsh effect on spermatogenesis.
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5
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Hampel U, Klonisch T, Sel S, Schulze U, Garreis F, Seitmann H, Zouboulis CC, Paulsen FP. Insulin-like factor 3 promotes wound healing at the ocular surface. Endocrinology 2013; 154:2034-45. [PMID: 23539510 DOI: 10.1210/en.2012-2201] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Tear fluid is known to contain many different hormones with relevance for ocular surface homeostasis. We studied the presence and functional role of insulin-like factor 3 (INSL3) and its cognate receptor RXFP2 (relaxin/insulin-like family peptide receptor 2) at the ocular surface and in tears. Expression of human INSL3 and RXFP2 was determined in tissues of the ocular surface and lacrimal apparatus; in human corneal (HCE), conjunctival (HCjE), and sebaceous (SC) epithelial cell lines; and in human tears by RT-PCR and ELISA. We investigated effects of human recombinant INSL3 (hrINSL3) on cell proliferation and cell migration and the influence of hrINSL3 on the expression of MMP2, -9, and -13 and TIMP1 and -2 was quantified by real-time PCR and ELISA in HCE, HCjE, and SC cells. We used a C57BL/6 mouse corneal defect model to elucidate the effect of topical application of hrINSL3 on corneal wound healing. INSL3 and RXFP2 transcripts and INSL3 protein were detected in all tissues and cell lines investigated. Significantly higher concentrations of INSL3 were detected in tears from male vs. female volunteers. Stimulation of HCE, HCjE, and SC with hrINSL3 significantly increased cell proliferation in HCjE and SC and migration of HCjE. Treatment with hrINSL3 for 24 hours regulated MMP2, TIMP1, and TIMP2 expression. The local application of hrINSL3 onto denuded corneal surface resulted in significantly accelerated corneal wound healing in mice. These findings suggest a novel and gender-specific role for INSL3 and cognate receptor RXFP2 signaling in ocular surface homeostasis and determined a novel role for hrINSL3 in corneal wound healing.
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Affiliation(s)
- Ulrike Hampel
- Department of Anatomy II, Friedrich Alexander University Erlangen-Nürnberg, Faculty of Medicine, Universitätsstrasse 19, 91054 Erlangen, Germany.
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6
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Bathgate RAD, Halls ML, van der Westhuizen ET, Callander GE, Kocan M, Summers RJ. Relaxin family peptides and their receptors. Physiol Rev 2013; 93:405-80. [PMID: 23303914 DOI: 10.1152/physrev.00001.2012] [Citation(s) in RCA: 372] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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.
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Affiliation(s)
- R A D Bathgate
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology, Monash University, Victoria, Australia
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7
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Scott DJ, Rosengren KJ, Bathgate RAD. The different ligand-binding modes of relaxin family peptide receptors RXFP1 and RXFP2. Mol Endocrinol 2012; 26:1896-906. [PMID: 22973049 DOI: 10.1210/me.2012-1188] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Relaxin and insulin-like peptide 3 (INSL3) are peptide hormones with a number of important physiological roles in reproduction, regulation of extracellular matrix turnover, and cardiovascular function. Relaxin and INSL3 mediate their actions through the closely related G-protein coupled receptors, relaxin family peptide receptors 1 and 2 (RXFP1 and RXFP2), respectively. These receptors have large extracellular domains (ECD) that contain high-affinity ligand-binding sites within their 10 leucine-rich repeat (LRR)-containing modules. Although relaxin can bind and activate both RXFP1 and RXFP2, INSL3 can only bind and activate RXFP2. To investigate whether this difference is related to the nature of the high-affinity ECD binding site or to differences in secondary binding sites involving the receptor transmembrane (TM) domain, we created a suite of constructs with RXFP1/2 chimeric ECD attached to single TM helices. We show that by changing as little as one LRR, representing four amino acid substitutions, we were able to engineer a high-affinity INSL3-binding site into the ECD of RXFP1. Molecular modeling of the INSL3-RXFP2 interaction based on extensive experimental data highlights the differences in the binding mechanisms of relaxin and INSL3 to the ECD of their cognate receptors. Interestingly, when the engineered RXFP1/2 ECD were introduced into full-length RXFP1 constructs, INSL3 exhibited only low affinity and efficacy on these receptors. These results highlight critical differences both in the ECD binding and in the coordination of the ECD-binding site with the TM domain, and provide new mechanistic insights into the binding and activation events of RXFP1 and RXFP2 by their native hormone ligands.
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Affiliation(s)
- Daniel J Scott
- Florey Neuroscience Institutes and the Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, Victoria 3010, Australia
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8
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Büllesbach EE, Schwabe C. Replacement of disulfides by amide bonds in the relaxin-like factor (RLF/INSL3) reveals a role for the A11-B10 link in transmembrane signaling. Biochemistry 2012; 51:4198-205. [PMID: 22574850 DOI: 10.1021/bi300352x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The relaxin-like factor (RLF) also named insulin-like 3 (INSL3) consists of two polypeptide chains linked by two interchain and one intrachain disulfide bond. RLF binds to its receptor (LGR8 also named RXFP2) through the B chain and initiates transmembrane communication by activating the adenylate cyclase through the N-terminal region of both chains. Cystine A11-B10 occupies a unique position on the molecular surface just outside the binding region and between the two signaling ports. We have synthesized an RLF analogue in which the disulfide A11-B10 was replaced by a peptide bond and found that cAMP production ceased while receptor binding was not affected. In contrast, replacing the disulfide A24-B22 by a peptide bond reduced potency proportional to the binding affinity and lowered efficacy to 65%, while replacing disulfide A10-A15 by a peptide bond reduced binding affinity to 32% and lowered potency to 7% but maintained 100% efficacy. The exceptional properties of the derivative bearing an A11-B10 isopeptide cross-link suggests that the disulfide has a special role in signal transduction. We propose that disulfide A11-B10 serves as an insulator between the two ports, whereas the amide functionality disturbs the signal transmission complex likely due to changes in polarity. The clear separation between receptor binding and signal activation sites within this small protein permits one to study how the relaxin-like factor initiates the signal on the receptor that induces intracellular cAMP production.
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Affiliation(s)
- Erika E Büllesbach
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA.
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9
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Bathgate RAD, Zhang S, Hughes RA, Rosengren KJ, Wade JD. The structural determinants of insulin-like Peptide 3 activity. Front Endocrinol (Lausanne) 2012; 3:11. [PMID: 22654853 PMCID: PMC3356098 DOI: 10.3389/fendo.2012.00011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 01/12/2012] [Indexed: 11/24/2022] Open
Abstract
Insulin-like peptide 3 (INSL3) is a hormone and/or paracrine factor which is a member of the relaxin peptide family. It has key roles as a fertility regulator in both males and females. The receptor for INSL3 is the leucine rich repeat (LRR) containing G-protein coupled receptor 8 (LGR8) which is now known as relaxin family peptide receptor 2 (RXFP2). Receptor activation by INSL3 involves binding to the LRRs in the large ectodomain of RXFP2 by residues within the B-chain of INSL3 as well as an interaction with the transmembrane exoloops of the receptor. Although the binding to the LRRs is well characterized the features of the peptide and receptor involved in the exoloop interaction are currently unknown. This study was designed to determine the key INSL3 determinants for RXFP2 activation. A chimeric peptide approach was first utilized to demonstrate that the A-chain is critical for receptor activation. Replacement of the INSL3 A-chain with that from the related peptides INSL5 and INSL6 resulted in complete loss of activity despite only minor changes in binding affinity. Subsequent replacement of specific A-chain residues with those from the INSL5 peptide highlighted that the N-terminus of the A-chain of INSL3 is critical for its activity. Remarkably, replacement of the entire N-terminus with four or five alanine residues resulted in peptides with near native activity suggesting that specific residues are not necessary for activity. Additionally removal of two amino acids at the C-terminus of the A-chain and mutation of Lys-8 in the B-chain also resulted in minor decreases in peptide activity. Therefore we have demonstrated that the activity of the INSL3 peptide is driven predominantly by residues 5-9 in the A-chain, with minor additional contributions from the two C-terminal A-chain residues and Lys-8 in the B-chain. Using this new knowledge, we were able to produce a truncated INSL3 peptide structure which retained native activity, despite having 14 fewer residues than the parent peptide.
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Affiliation(s)
- Ross A. D. Bathgate
- Florey Neuroscience Institutes, University of MelbourneMelbourne, VIC, Australia
- Department of Biochemistry and Molecular Biology, University of MelbourneMelbourne, VIC, Australia
- *Correspondence: Ross A. D. Bathgate and John D. Wade, Florey Neuroscience Institutes, University of Melbourne, Melbourne, VIC 3031, Australia. e-mail: ;
| | - Soude Zhang
- Florey Neuroscience Institutes, University of MelbourneMelbourne, VIC, Australia
| | - Richard A. Hughes
- Department of Pharmacology, University of MelbourneMelbourne, VIC, Australia
| | - K. Johan Rosengren
- School of Biomedical Sciences, The University of QueenslandBrisbane, QLD, Australia
| | - John D. Wade
- Florey Neuroscience Institutes, University of MelbourneMelbourne, VIC, Australia
- School of Chemistry, University of MelbourneMelbourne, VIC, Australia
- *Correspondence: Ross A. D. Bathgate and John D. Wade, Florey Neuroscience Institutes, University of Melbourne, Melbourne, VIC 3031, Australia. e-mail: ;
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Shabanpoor F, Zhang S, Hughes RA, Hossain MA, Layfield S, Ferraro T, Bathgate RAD, Separovic F, Wade JD. Design and development of analogues of dimers of insulin-like peptide 3 B-chain as high-affinity antagonists of the RXFP2 receptor. Biopolymers 2011; 96:81-7. [PMID: 20560146 DOI: 10.1002/bip.21484] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Insulin-like peptide 3 (INSL3) is one of 10 members of the human relaxin-insulin superfamily of peptides. It is a peptide hormone that is expressed by fetal and postnatal testicular Leydig cells and postnatal ovarian thecal cells. It mediates testicular descent during fetal life and suppresses sperm apoptosis in adult males, whereas, in females, it causes oocyte maturation. INSL3 has also been shown to promote thyroid tumor growth and angiogenesis in human. These actions of INSL3 are mediated through its G protein-coupled receptor, RXFP2. INSL3, a two-chained peptide, binds to its receptor primarily via its B-chain, whereas elements of the A-chain are essential for receptor activation. In an attempt to design a high-affinity antagonist with potential clinical application as an anticancer agent as well as a contraceptive, we have previously prepared a synthetic parallel dimer of INSL3 B-chain and demonstrated that it binds to RXFP2 with high affinity. In this work, we undertook full pharmacological characterization of this peptide and show that it can antaogonize INSL3-mediated cAMP signaling through RXFP2. Further refinement by truncation of 18 residues yielded a minimized analogue that retained full binding affinity and INSL3 antagonism. It is an attractive lead peptide for in vivo evaluation as an inhibitor of male and female fertility and of INSL3-mediated carcinogenesis.
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Affiliation(s)
- Fazel Shabanpoor
- Howard Florey Institute, University of Melbourne, Melbourne, VIC 3010, Australia
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Abstract
PURPOSE OF REVIEW Insulin-like peptide 3 (INSL3) is the subject of a fast expanding literature reflecting increasing clinical application, particularly as a diagnostic parameter. This review summarizes the recent INSL3 literature published within the last 12-18 months. RECENT FINDINGS Significant inroads have been made to understand how INSL3 is working in testicular descent. It also has other functions in the adult, for example in bone metabolism, extending its role as a largely gender-specific hormone. Advances in molecular pharmacology have increased our understanding of INSL3 interaction with its specific receptor, RXFP2, and delivered new high-affinity antagonists. INSL3 is increasingly being used to assess Leydig cell functional capacity within the testis, independently of factors affecting the hypothalamic-pituitary-gonadal axis, being a robust parameter by comparison with testosterone. Particularly in the aging male, metabolic syndrome, and the effects of adiposity on testis function, INSL3 is a valuable adjunct to the standard clinical repertoire. SUMMARY The Leydig cell hormone INSL3 is responsible for the first phase of testicular descent during pregnancy and may have multiple roles as a gender-specific circulating hormone in the adult reflecting Leydig cell functional capacity. In women, INSL3 is a paracrine factor within the ovary and probably placenta, in which it may have a fetal gender-specific role.
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Affiliation(s)
- Richard Ivell
- School of Molecular and Biomedical Science, University of Adelaide, Australia.
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12
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Zhang S, Hughes RA, Bathgate RAD, Shabanpoor F, Hossain MA, Lin F, van Lierop B, Robinson AJ, Wade JD. Role of the intra-A-chain disulfide bond of insulin-like peptide 3 in binding and activation of its receptor, RXFP2. Peptides 2010; 31:1730-6. [PMID: 20570702 DOI: 10.1016/j.peptides.2010.05.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 05/29/2010] [Accepted: 05/29/2010] [Indexed: 10/19/2022]
Abstract
INSL3 is a member of the insulin-IGF-relaxin superfamily and plays a key role in male fetal development and in adult germ cell maturation. It is the cognate ligand for RXFP2, a leucine-rich repeat containing G-protein coupled receptor. To date, and in contrast to our current knowledge of the key structural features that are required for the binding of INSL3 to RXFP2, comparatively little is known about the key residues that are required to elicit receptor activation and downstream cell signaling. Early evidence suggests that these are contained principally within the A-chain. To further explore this hypothesis, we have undertaken an examination of the functional role of the intra-A-chain disulfide bond. Using solid-phase peptide synthesis together with regioselective disulfide bond formation, two analogs of human INSL3 were prepared in which the intra-chain disulfide bond was replaced, one in which the corresponding Cys residues were substituted with the isosteric Ser and the other in which the Cys were removed altogether. Both of these peptides retained nearly full RXFP2 receptor binding but were devoid of cAMP activity (receptor activation), indicating that the intra-A-chain disulfide bond makes a significant contribution to the ability of INSL3 to act as an RXFP2 agonist. Replacement of the disulfide bond with a metabolically stable dicarba bond yielded two isomers of INSL3 that each exhibited bioactivity similar to native INSL3. This study highlights the critical structural role played by the intra-A-chain disulfide bond of INSL3 in mediating agonist actions through the RXFP2 receptor.
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Affiliation(s)
- Suode Zhang
- Howard Florey Institute, University of Melbourne, Victoria 3010, Australia
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13
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Ruan J, Du WD. [Male infertility and gene defects]. YI CHUAN = HEREDITAS 2010; 32:411-22. [PMID: 20466627 DOI: 10.3724/sp.j.1005.2010.00411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
About 15% of the couples at reproductive age worldwide suffer from infertility. It is estimated that 50% of the entity result from male itself. The mechanism of male infertility is quite complicated, attributing to inherent and environment factors of the infertility patients, of which defects of fertility-related genes are of importance for its occurrence. The clinical features of male infertility vary from azoospermia to oligoasthenoteratozoospermia. This paper presents the relationship between the known defects in genes and male infertility.
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Affiliation(s)
- Jian Ruan
- Key Lab of Gene Resource Utilization for Severe Hereditary Diseases of Ministry Education & Key Lab of Genome Research of Anhui Province, Anhui Medical University, Hefei 230032, China.
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Kong RCK, Shilling PJ, Lobb DK, Gooley PR, Bathgate RAD. Membrane receptors: structure and function of the relaxin family peptide receptors. Mol Cell Endocrinol 2010; 320:1-15. [PMID: 20138959 DOI: 10.1016/j.mce.2010.02.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Revised: 12/14/2009] [Accepted: 02/02/2010] [Indexed: 01/17/2023]
Abstract
The receptors for members of the relaxin peptide family have only recently been discovered and are G-protein-coupled receptors (GPCRs). Relaxin and insulin-like peptide 3 (INSL3) interact with the leucine-rich-repeat-containing GPCRs (LGRs) LGR7 and LGR8, respectively. These receptors show closest similarity to the glycoprotein hormone receptors and contain large ectodomains with 10 leucine-rich repeats (LRRs) but are unique members of the LGR family (class C) as they have an LDL class A (LDLa) module at their N-terminus. In contrast, relaxin-3 and INSL5 interact with another class of type I GPCRs which lack a large ectodomain, the peptide receptors GPCR135 and GPCR142, respectively. These receptors are now classified as relaxin family peptide (RXFP) receptors, RXFP1 (LGR7), RXFP2 (LGR8), RXFP3 (GPCR135) and RXFP4 (GPCR142). This review outlines the identification of the peptides and receptors, their expression profiles and physiological roles and the functional interactions of the peptides with their unique receptors.
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Affiliation(s)
- Roy C K Kong
- Florey Neuroscience Institutes, University of Melbourne, Victoria 3010, Australia
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15
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16
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Luo X, Bathgate RAD, Liu YL, Shao XX, Wade JD, Guo ZY. Recombinant expression of an insulin-like peptide 3 (INSL3) precursor and its enzymatic conversion to mature human INSL3. FEBS J 2009; 276:5203-11. [PMID: 19674100 DOI: 10.1111/j.1742-4658.2009.07216.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Insulin-like peptide 3 (INSL3), which is primarily expressed in the Leydig cells of the testes, is a member of the insulin superfamily of peptide hormones. One of its primary functions is to initiate and mediate descent of the testes of the male fetus via interaction with its G protein-coupled receptor, RXFP2. Study of the peptide has relied upon chemical synthesis of the separate A- and B-chains and subsequent chain recombination. To establish an alternative approach to the preparation of human INSL3, we designed and recombinantly expressed a single-chain INSL3 precursor in Escherichia coli cells. The precursor was solubilized from the inclusion body, purified almost to homogeneity by immobilized metal-ion affinity chromatography and refolded efficiently in vitro. The refolded precursor was subsequently converted to mature human INSL3 by sequential endoproteinase Lys-C and carboxypeptidase B treatment. CD spectroscopic analysis and peptide mapping showed that the refolded INSL3 possessed an insulin-like fold with the expected disulfide linkages. Recombinant human INSL3 demonstrated full activity in stimulating cAMP activity in RXFP2-expressing cells. Interestingly, the activity of the single-chain precursor was comparable with that of the mature two-chain INSL3, suggesting that the receptor-binding region within the mid- to C-terminal of B-chain is maintained in an active conformation in the precursor. This study not only provides an efficient approach for mature INSL3 preparation, but also resulted in the acquisition of a useful single-chain template for additional structural and functional studies of the peptide.
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Affiliation(s)
- Xiao Luo
- Institute of Protein Research, East Hospital, Tongji University, Shanghai, China
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17
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De Meyts P, Gauguin L, Svendsen AM, Sarhan M, Knudsen L, Nøhr J, Kiselyov VV. Structural basis of allosteric ligand-receptor interactions in the insulin/relaxin peptide family: implications for other receptor tyrosine kinases and G-protein-coupled receptors. Ann N Y Acad Sci 2009; 1160:45-53. [PMID: 19416158 DOI: 10.1111/j.1749-6632.2009.03837.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The insulin/relaxin superfamily of peptide hormones comprises 10 members in humans. The three members of the insulin-related subgroup bind to receptor tyrosine kinases (RTKs), while four of the seven members of the relaxin-like subgroup are now known to bind to G-protein-coupled receptors (GPCRs), the so-called relaxin family peptide receptors (RXFPs). Both systems have a long evolutionary history and play a critical role in fundamental biological processes, such as metabolism, growth, survival and longevity, and reproduction. The structural biology and ligand-binding kinetics of the insulin and insulin-like growth factor I receptors have been studied in great detail, culminating in the recent crystal structure of the insulin receptor extracellular domain. Some of the fundamental properties of these receptors, including constitutive dimerization and negative cooperativity, have recently been shown to extend to other RTKs and GPCRs, including RXFPs, confirming kinetic observations made over 30 years ago.
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Affiliation(s)
- Pierre De Meyts
- Receptor Systems Biology Laboratory, Hagedorn Research Institute, Gentofte, Denmark
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18
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Schwabe C, Büllesbach EE. The "hot wires" of the relaxin-like factor (Insl3). Ann N Y Acad Sci 2009; 1160:93-8. [PMID: 19416166 DOI: 10.1111/j.1749-6632.2008.03779.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The discovery of the total separation of receptor-binding and signal-generating regions of the relaxin-like factor (RLF) has provided an opportunity to investigate the mechanism of transmembrane signaling. The receptor-binding residues of RLF are in the B chain of the two-chain molecule and extend from the midregion of the central helix to the tryptophan in position B27. The signal initiation site resides in two residues before the N-terminal cysteine in each chain. For optimal signaling the RLF requires five L-alpha-amino acids preceding cysteine A10, whereas the B chain requires only three. The nature of the side chains of these amino acids is not critical for the signaling function. Heuristic arguments lead us to suggest that the peptide bond is the signal-generating feature of RLF and possibly of other peptide hormones.
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Affiliation(s)
- Christian Schwabe
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, USA.
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Feng S, Ferlin A, Truong A, Bathgate R, Wade JD, Corbett S, Han S, Tannour-Louet M, Lamb DJ, Foresta C, Agoulnik AI. INSL3/RXFP2 signaling in testicular descent. Ann N Y Acad Sci 2009; 1160:197-204. [PMID: 19416188 DOI: 10.1111/j.1749-6632.2009.03841.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mutations of the insulin-like peptide 3 (INSL3) hormone or its receptor, RXFP2, cause intraabdominal cryptorchidism in male mice. Specific RXFP2 expression in mouse gubernacula was detected at embryonic day 14.5 and markedly increased after birth in the developing cremaster muscle, as well as in the epididymis and testicular Leydig and germ cells. INSL3 treatment stimulated cell proliferation of embryonic gubernacular and Leydig cells, implicating active INSL3-mediated signaling. The transcription factor SOX9, a known male sex determination factor, upregulated the activity of the RXFP2 promoter. INSL3 is sufficient to direct the first transabdominal phase of testicular descent in the absence of hypothalamic-pituitary-gonadal axis signaling or Hoxa10, although these factors are important for inguinoscrotal testicular descent. Similarly, conditional ablation of the androgen receptor gene in gubernacular cells resulted in disruption of inguinoscrotal descent. We performed mutation screening of INSL3 and RXFP2 in human patients with cryptorchidism and control subjects from different populations in Europe and the USA. Several missense mutations were described in both the INSL3 and RXFP2 genes. A novel V39G INSL3 mutation in a patient with cryptorchidism was identified; however, the functional analysis of the mutant peptide did not reveal compromised function. In more than 2000 patients and controls analyzed to date, the T222P RXFP2 mutation is the only one strongly associated with the mutant phenotype. The T222P mutant receptor, when transfected into 293T cells, had severely decreased cell membrane expression, providing the basis for the functional deficiency of this mutation.
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Affiliation(s)
- Shu Feng
- Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas 77030, USA
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Halls ML, Papaioannou M, Wade JD, Evans BA, Bathgate RAD, Summers RJ. RXFP1 couples to the Galpha-Gbetagamma-PI3K-PKCzeta pathway via the final 10 amino acids of the receptor C-terminal tail. Ann N Y Acad Sci 2009; 1160:117-20. [PMID: 19416171 DOI: 10.1111/j.1749-6632.2008.03813.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The relaxin family peptide receptors RXFP1 and RXFP2 are highly similar receptors that share approximately 80% amino acid sequence homology. Constitutively active receptors couple to increased cAMP accumulation, which is important for relaxin-mediated decidualization and myometrial inhibition. Despite the high homology, the receptors couple to different G-proteins to affect cAMP accumulation. This study aimed to determine the region of RXFP1 that directs coupling to the delayed Galpha(i3) pathway by using receptor mutagenesis. Receptor chimeras suggested that activation of this pathway by RXFP1 was dependent upon the membrane-anchored domain of the receptor. Further receptor mutagenesis showed that activation of the Galpha(i3)-Gbetagamma-PI3K-PKCzeta cAMP pathway by RXFP1 is dependent upon the C-terminal 10 amino acids of the receptor and absolutely requires Arg(752).
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Affiliation(s)
- Michelle L Halls
- Department of Pharmacology, Monash University, Clayton, Victoria 3800, Australia
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21
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Tregear GW, Bathgate RAD, Hossain MA, Lin F, Zhang S, Shabanpoor F, Scott DJ, Ma S, Gundlach AL, Samuel CS, Wade JD. Structure and Activity in the Relaxin Family of Peptides. Ann N Y Acad Sci 2009; 1160:5-10. [DOI: 10.1111/j.1749-6632.2009.03955.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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22
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Ivell R, Anand-Ivell R. Biology of insulin-like factor 3 in human reproduction. Hum Reprod Update 2009; 15:463-76. [DOI: 10.1093/humupd/dmp011] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Schwabe C, Büllesbach EE. Relaxin, the relaxin-like factor and their receptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 612:14-25. [PMID: 18161478 DOI: 10.1007/978-0-387-74672-2_2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In 1926 Frederick Hisaw discovered a blood-borne factor in pregnant guinea pigs that would cause relaxation of the pubic symphysis in virgin females of the species. The relaxin-like factor gene (RLF), also known as insulin-like 3 (INSL3), was recovered from a library of testicular cDNA. The function of RLF as the mediator of testicular positioning in mice was discovered by gene deletion experiments. The report that deletion of a G-protein-coupled receptor in a mouse mutant caused cryptorchidism and that relaxin and RLF and their receptors were structurally and functionally similar may well have inspired Drs. Hsueh and Sherwood to put LGR7 and relaxin together and thus, after many agonizing years of uncertainty, the relaxin receptor had yielded its identity. LGR8 was recognized as the human version of the RLF receptor and together LGR7 and LGR8, with their respective ligands, opened to detailed investigation the large and important field of G-protein activated leucine-rich repeat receptors. In the process RLF and LGR8 have yielded some general information that might contribute to our knowledge of receptor/ligand interaction, in particular the enigmatic signal initiation process.
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Affiliation(s)
- Christian Schwabe
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, PO Box 250509, Charleston, SC 29425, USA.
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Büllesbach EE, Hass MAS, Jensen MR, Hansen DF, Kristensen SM, Schwabe C, Led JJ. Solution Structure of a Conformationally Restricted Fully Active Derivative of the Human Relaxin-like Factor. Biochemistry 2008; 47:13308-17. [DOI: 10.1021/bi801412w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Erika E. Büllesbach
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, P.O. Box 250509, Charleston, South Carolina 29425, and Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Mathias A. S. Hass
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, P.O. Box 250509, Charleston, South Carolina 29425, and Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Malene R. Jensen
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, P.O. Box 250509, Charleston, South Carolina 29425, and Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - D. Flemming Hansen
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, P.O. Box 250509, Charleston, South Carolina 29425, and Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Søren M. Kristensen
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, P.O. Box 250509, Charleston, South Carolina 29425, and Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Christian Schwabe
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, P.O. Box 250509, Charleston, South Carolina 29425, and Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Jens J. Led
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, P.O. Box 250509, Charleston, South Carolina 29425, and Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
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Park JI, Semyonov J, Yi W, Chang CL, Hsu SYT. Regulation of receptor signaling by relaxin A chain motifs: derivation of pan-specific and LGR7-specific human relaxin analogs. J Biol Chem 2008; 283:32099-109. [PMID: 18772127 DOI: 10.1074/jbc.m806817200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Relaxin peptides are important hormones for the regulation of reproductive tissue remodeling and the renal cardiovascular system during pregnancy. Recent studies demonstrated that two of the seven human relaxin family peptides, relaxin H2 (RLN2) and INSL3, signal exclusively through leucine-rich repeat-containing G protein-coupled receptors, LGR7 and LGR8. Although it was well characterized that an RXXXRXXI motif at the RLN2 B chain confers receptor activation activity, it is not clear what roles RLN2 A chain plays in receptor interaction. Analyses of relaxin family genes on syntenic regions of model tetrapods showed that the A chain of RLN2 orthologs exhibited a greater sequence divergence as compared with the receptor-binding domain-containing B chain, foreshadowing a potential role in receptor interactions; hence, defining receptor selectivity in this fast evolving peptide hormone. To test our hypothesis that select residues in the human RLN2 A chain play key roles in receptor interaction, we studied mutant peptides with residue substitution(s) in the A chain. Here, we showed that alanine substitution at the A16 and A17 positions enhances LGR8-activation activity of RLN2, whereas mutation at the A22-23 region (RLN2A22-23) ablates LGR8, but not LGR7, activation activity. In addition, we demonstrated that the functional characteristics of the RLN2A22-23 mutant are mainly attributed to modifications at the PheA23 position. Taken together, our studies indicated that ThrA16, LysA17, and PheA23 constitute part of the receptor-binding interface of human RLN2, and that modification of these residues has led to the generation of novel human RLN2 analogs that would allow selective activation of human LGR7, but not LGR8, in vivo.
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Affiliation(s)
- Jae-Il Park
- Reproductive Biology and Stem Cell Research Program, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California 94305-5317, USA
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An insulin-like peptide regulates egg maturation and metabolism in the mosquito Aedes aegypti. Proc Natl Acad Sci U S A 2008; 105:5716-21. [PMID: 18391205 DOI: 10.1073/pnas.0800478105] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Ingestion of vertebrate blood is essential for egg maturation and transmission of disease-causing parasites by female mosquitoes. Prior studies with the yellow fever mosquito, Aedes aegypti, indicated blood feeding stimulates egg production by triggering the release of hormones from medial neurosecretory cells in the mosquito brain. The ability of bovine insulin to stimulate a similar response further suggested this trigger is an endogenous insulin-like peptide (ILP). A. aegypti encodes eight predicted ILPs. Here, we report that synthetic ILP3 dose-dependently stimulated yolk uptake by oocytes and ecdysteroid production by the ovaries at lower concentrations than bovine insulin. ILP3 also exhibited metabolic activity by elevating carbohydrate and lipid storage. Binding studies using ovary membranes indicated that ILP3 had an IC(50) value of 5.9 nM that was poorly competed by bovine insulin. Autoradiography and immunoblotting studies suggested that ILP3 binds the mosquito insulin receptor (MIR), whereas loss-of-function experiments showed that ILP3 activity requires MIR expression. Overall, our results identify ILP3 as a critical regulator of egg production by A. aegypti.
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Büllesbach EE, Boockfor FR, Fullbright G, Schwabe C. Cryptorchidism induced in normal rats by the relaxin-like factor inhibitor. Reproduction 2008; 135:351-5. [DOI: 10.1530/rep-07-0330] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cryptorchidism is a serious problem, which affects 2–5% of the male population. Failure of the testes to descend into the scrotal region impairs germ cell development and is associated with a greater incidence of testicular cancer. The relaxin-like factor (RLF or insulin-like-3) has been shown to be critically important for the timely descent of the testicles in mice. We have discovered that the signal initiation site of the RLF can be eliminated without measurable effects on hormone binding to its receptor and that the resulting RLF derivative is a competitive inhibitor of RLF called RLFi. RLFi administered to pregnant rats causes dose-dependent gonadal retention in the offspring. The ability to control the severity of the syndrome by altering the concentration of RLFi and the timing of administration enables us to study in detail the structural changes that are associated with the action of RLF during critical stages of development. Targeted inhibition of the physiological migration pattern of testicles by RLFi lets one dissect the physiological process such as to find a window for clinical application of RLF and to search for ancillary factors that might play a role during normal development.
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Scott DJ, Wilkinson TN, Zhang S, Ferraro T, Wade JD, Tregear GW, Bathgate RAD. Defining the LGR8 Residues Involved in Binding Insulin-Like Peptide 3. Mol Endocrinol 2007; 21:1699-712. [PMID: 17473281 DOI: 10.1210/me.2007-0097] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
The peptide hormone insulin-like peptide 3 (INSL3) is essential for testicular descent and has been implicated in the control of adult fertility in both sexes. The human INSL3 receptor leucine-rich repeat-containing G protein-coupled receptor 8 (LGR8) binds INSL3 and relaxin with high affinity, whereas the relaxin receptor LGR7 only binds relaxin. LGR7 and LGR8 bind their ligands within the 10 leucine-rich repeats (LRRs) that comprise the majority of their ectodomains. To define the primary INSL3 binding site in LGR8, its LRRs were first modeled on the crystal structure of the Nogo receptor (NgR) and the most likely binding surface identified. Multiple sequence alignment of this surface revealed the presence of seven of the nine residues implicated in relaxin binding to LGR7. Replacement of these residues with alanine caused reduced [125I]INSL3 binding, and a specific peptide/receptor interaction point was revealed using competition binding assays with mutant INSL3 peptides. This point was used to crudely dock the solution structure of INSL3 onto the LRR model of LGR8, allowing the prediction of the INSL3 Trp-B27 binding site. This prediction was then validated using mutant INSL3 peptide competition binding assays on LGR8 mutants. Our results indicated that LGR8 Asp-227 was crucial for binding INSL3 Arg-B16, whereas LGR8 Phe-131 and Gln-133 were involved in INSL3 Trp-B27 binding. From these two defined interactions, we predicted the complete INSL3/LGR8 primary binding site, including interactions between INSL3 His-B12 and LGR8 Trp-177, INSL3 Val-B19 and LGR8 Ile-179, and INSL3 Arg-B20 with LGR8 Asp-181 and Glu-229.
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Affiliation(s)
- Daniel J Scott
- Howard Florey Institute, The University of Melbourne, Melbourne, Victoria 3001, Australia
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Halls ML, van der Westhuizen ET, Bathgate RAD, Summers RJ. Relaxin family peptide receptors--former orphans reunite with their parent ligands to activate multiple signalling pathways. Br J Pharmacol 2007; 150:677-91. [PMID: 17293890 PMCID: PMC2013861 DOI: 10.1038/sj.bjp.0707140] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The relaxin family peptides, although structurally closely related to insulin, act on a group of four G protein-coupled receptors now known as Relaxin Family Peptide (RXFP) Receptors. The leucine-rich repeat containing RXFP1 and RXFP2 and the small peptide-like RXFP3 and RXFP4 are the physiological targets for relaxin, insulin-like (INSL) peptide 3, relaxin-3 and INSL5, respectively. RXFP1 and RXFP2 have at least two binding sites--a high-affinity site in the leucine-rich repeat region of the ectodomain and a lower-affinity site in an exoloop of the transmembrane region. Although they respond to peptides that are structurally similar, RXFP3 and RXFP4 demonstrate distinct binding properties with relaxin-3 being the only peptide that can recognize these receptors in addition to RXFP1. Activation of RXFP1 or RXFP2 causes increased cAMP and the initial response for both receptors is the resultant of Gs-mediated activation and G(oB)-mediated inhibition of adenylate cyclase. With RXFP1, an additional delayed increase in cAMP involves betagamma subunits released from G(i3). In contrast, RXFP3 and RXFP4 inhibit adenylate cyclase and RXFP3 causes ERK1/2 phosphorylation. Drugs acting at RXFP1 have potential for the treatment of diseases involving tissue fibrosis such as cardiac and renal failure, asthma and scleroderma and may also be useful to facilitate embryo implantation. Activators of RXFP2 may be useful to treat cryptorchidism and infertility and inhibitors have potential as contraceptives. Studies of the distribution and function of RXFP3 suggest that it is a potential target for anti-anxiety and anti-obesity drugs.
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MESH Headings
- Amino Acid Sequence
- Animals
- Conserved Sequence
- Evolution, Molecular
- Female
- Humans
- Ligands
- Male
- Models, Biological
- Models, Molecular
- Molecular Sequence Data
- Protein Isoforms/chemistry
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Peptide/chemistry
- Receptors, Peptide/genetics
- Receptors, Peptide/metabolism
- Relaxin/metabolism
- Sequence Homology, Amino Acid
- Signal Transduction/physiology
- Tissue Distribution
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Affiliation(s)
- M L Halls
- Department of Pharmacology, Monash University, Clayton Victoria, Australia
| | | | - R A D Bathgate
- Howard Florey Institute, University of Melbourne Victoria, Australia
| | - R J Summers
- Department of Pharmacology, Monash University, Clayton Victoria, Australia
- Author for correspondence:
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