1
|
Syryn H, Van de Velde J, De Clercq G, Verdin H, Dheedene A, Peelman F, Sinclair A, Ayers KL, Bathgate RAD, Cools M, De Baere E. Biallelic RXFP2 variants lead to congenital bilateral cryptorchidism and male infertility, supporting a role of RXFP2 in spermatogenesis. Hum Reprod 2024:deae195. [PMID: 39222519 DOI: 10.1093/humrep/deae195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 07/02/2024] [Indexed: 09/04/2024] Open
Abstract
STUDY QUESTION Does RXFP2 disruption impair male fertility? SUMMARY ANSWER We identified biallelic variants in RXFP2 in patients with male infertility due to spermatogenic arrest at the spermatid stage, supporting a role of RXFP2 in human spermatogenesis, specifically in germ cell maturation. WHAT IS KNOWN ALREADY Since RXFP2, the receptor for INSL3, plays a crucial role in testicular descent during prenatal development, biallelic variants lead to bilateral cryptorchidism, as described in four families to date. While animal models have also suggested a function in spermatogenesis, the postnatal functions of RXFP2 and its ligand INSL3, produced in large amounts by the testes from puberty throughout adulthood, are largely unknown. STUDY DESIGN, SIZE, DURATION A family with two male members affected by impaired fertility due to spermatogenic maturation arrest and a history of bilateral cryptorchidism underwent clinical, endocrinological, histological, genomic, in vitro cellular, and in silico investigations. PARTICIPANTS/MATERIALS, SETTING, METHODS The endocrinological and histological findings were correlated with publicly available single-cell RNA sequencing (scRNA-seq) data. The genomic defects have been characterized using long-read sequencing and validated with in silico modeling and an in vitro cyclic AMP reporter gene assay. MAIN RESULTS AND THE ROLE OF CHANCE An intragenic deletion of exon 1-5 of RXFP2 (NM_130806.5) was detected in trans with a hemizygous missense variant c.229G>A, p.(Glu77Lys). The p.(Glu77Lys) variant caused no clear change in cell surface expression or ability to bind INSL3, but displayed absence of a cAMP signal in response to INSL3, indicating a loss-of-function. Testicular biopsy in the proband showed a maturation arrest at the spermatid stage, corresponding to the highest level of RXFP2 expression in scRNA-seq data, thereby providing a potential explanation for the impaired fertility. LIMITATIONS, REASONS FOR CAUTION Although this is so far the only study of human cases that supports the role of RXFP2 in spermatogenic maturation, this is corroborated by several animal studies that have already demonstrated a postnatal function of INSL3 and RXFP2 in spermatogenesis. WIDER IMPLICATIONS OF THE FINDINGS This study corroborates RXFP2 as gene implicated in autosomal recessive congenital bilateral cryptorchidism due to biallelic variants, rather than autosomal-dominant cryptorchidism due to monoallelic RXFP2 variants. Our findings also support that RXFP2 is essential in human spermatogenesis, specifically in germ cell maturation, and that biallelic disruption can cause male infertility through spermatogenic arrest at the spermatid stage. STUDY FUNDING/COMPETING INTEREST(S) Funding was provided by the Bellux Society for Pediatric Endocrinology and Diabetology (BELSPEED) and supported by a Research Foundation Flanders (FWO) senior clinical investigator grant (E.D.B., 1802220N) and a Ghent University Hospital Special Research Fund grant (M.C., FIKO-IV institutional fund). The authors declare no conflict of interest. TRIAL REGISTRATION NUMBER N/A.
Collapse
Affiliation(s)
- Hannes Syryn
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Julie Van de Velde
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Department of Pediatric Endocrinology, Ghent University Hospital, Ghent, Belgium
| | - Griet De Clercq
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Hannah Verdin
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Annelies Dheedene
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Frank Peelman
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Andrew Sinclair
- Royal Children's Hospital & Department of Paediatrics, Murdoch Children's Research Institute, University of Melbourne, Melbourne, Australia
| | - Katie L Ayers
- Royal Children's Hospital & Department of Paediatrics, Murdoch Children's Research Institute, University of Melbourne, Melbourne, Australia
| | - Ross A D Bathgate
- The Florey Institute and Department of Biochemistry and Pharmacology, University of Melbourne, Melbourne, Australia
| | - Martine Cools
- Department of Pediatric Endocrinology, Ghent University Hospital, Ghent, Belgium
- Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
| | - Elfride De Baere
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| |
Collapse
|
2
|
Speck D, Kleinau G, Meininghaus M, Erbe A, Einfeldt A, Szczepek M, Scheerer P, Pütter V. Expression and Characterization of Relaxin Family Peptide Receptor 1 Variants. Front Pharmacol 2022; 12:826112. [PMID: 35153771 PMCID: PMC8832513 DOI: 10.3389/fphar.2021.826112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 12/31/2021] [Indexed: 12/31/2022] Open
Abstract
G-protein coupled receptors (GPCR) transduce extracellular stimuli into the cell interior and are thus centrally involved in almost all physiological-neuronal processes. This essential function and association with many diseases or pathological conditions explain why GPCRs are one of the priority targets in medical and pharmacological research, including structure determination. Despite enormous experimental efforts over the last decade, both the expression and purification of these membrane proteins remain elusive. This is attributable to specificities of each GPCR subtype and the finding of necessary experimental in vitro conditions, such as expression in heterologous cell systems or with accessory proteins. One of these specific GPCRs is the leucine-rich repeat domain (LRRD) containing GPCR 7 (LGR7), also termed relaxin family peptide receptor 1 (RXFP1). This receptor is characterized by a large extracellular region of around 400 amino acids constituted by several domains, a rare feature among rhodopsin-like (class A) GPCRs. In the present study, we describe the expression and purification of RXFP1, including the design of various constructs suitable for functional/biophysical studies and structure determination. Based on available sequence information, homology models, and modern biochemical and genetic tools, several receptor variations with different purification tags and fusion proteins were prepared and expressed in Sf9 cells (small-scale), followed by an analytic fluorescence-detection size-exclusion chromatography (F-SEC) to evaluate the constructs. The most promising candidates were expressed and purified on a large-scale, accompanied by ligand binding studies using surface plasmon resonance spectroscopy (SPR) and by determination of signaling capacities. The results may support extended studies on RXFP1 receptor constructs serving as targets for small molecule ligand screening or structural elucidation by protein X-ray crystallography or cryo-electron microscopy.
Collapse
Affiliation(s)
- David Speck
- Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Berlin, Germany
| | - Gunnar Kleinau
- Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Berlin, Germany
| | - Mark Meininghaus
- Bayer AG, Research and Development, Pharmaceuticals, Wuppertal, Germany
| | - Antje Erbe
- Bayer AG, Research and Development, Pharmaceuticals, Berlin, Germany
- NUVISAN ICB GmbH, Berlin, Germany
| | - Alexandra Einfeldt
- Bayer AG, Research and Development, Pharmaceuticals, Berlin, Germany
- NUVISAN ICB GmbH, Berlin, Germany
| | - Michal Szczepek
- Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Berlin, Germany
| | - Patrick Scheerer
- Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Berlin, Germany
- *Correspondence: Patrick Scheerer, ; Vera Pütter,
| | - Vera Pütter
- Bayer AG, Research and Development, Pharmaceuticals, Berlin, Germany
- NUVISAN ICB GmbH, Berlin, Germany
- *Correspondence: Patrick Scheerer, ; Vera Pütter,
| |
Collapse
|
3
|
Evidence for existence of insulin-like factor 3 (INSL3) hormone-receptor system in the ovarian corpus luteum and extra-ovarian reproductive organs during pregnancy in goats. Cell Tissue Res 2021; 385:173-189. [PMID: 33590284 DOI: 10.1007/s00441-021-03410-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Accepted: 01/01/2021] [Indexed: 10/22/2022]
Abstract
Insulin-like factor 3 (INSL3), initially described as a male hormone, is expressed in female reproductive organs during the estrous cycle and pregnancy but its function has not yet been established. This study explores the function of INSL3 in pregnant Saanen goats by characterizing the expression dynamics of INSL3 and its receptor, relaxin family peptide receptor 2 (RXFP2) and by demonstrating specific INSL3 binding in reproductive organs, using molecular and immunological approaches and ligand-receptor interaction assays. We demonstrate that the corpus luteum (CL) acts as both a source and target of INSL3 in pregnant goats, while extra-ovarian reproductive organs serve as additional INSL3 targets. The expression of INSL3 and RXFP2 in the CL reached maximum levels in middle pregnancy, followed by a decrease in late pregnancy; in contrast, RXFP2 expression levels in extra-ovarian reproductive organs were higher in the mammary glands but lower in the uterus, cervix and placenta and did not significantly change during pregnancy. The functional RXFP2 enabling INSL3 to bind was identified as an ~ 85 kDa protein in both the CL and mammary glands and localized in large and small luteal cells in the CL and in tubuloalveolar and ductal epithelial cells in the mammary glands. Additionally, INSL3 also bound to multiple cell types expressing RXFP2 in the uterus, cervix and placenta in a hormone-specific and saturable manner. These results provide evidence that an active intra- and extra-ovarian INSL3 hormone-receptor system operates during pregnancy in goats.
Collapse
|
4
|
Goth CK, Petäjä-Repo UE, Rosenkilde MM. G Protein-Coupled Receptors in the Sweet Spot: Glycosylation and other Post-translational Modifications. ACS Pharmacol Transl Sci 2020; 3:237-245. [PMID: 32296765 DOI: 10.1021/acsptsci.0c00016] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Indexed: 12/11/2022]
Abstract
Post-translational modifications (PTMs) are a fundamental phenomenon across all classes of life and several hundred different types have been identified. PTMs contribute widely to the biological functions of proteins and greatly increase their diversity. One important class of proteins regulated by PTMs, is the cell surface expressed G protein-coupled receptors (GPCRs). While most PTMs have been shown to exert distinct biological functions, we are only beginning to approach the complexity that the potential interplay between different PTMs may have on biological functions and their regulation. Importantly, PTMs and their potential interplay represent an appealing mechanism for cell and tissue specific regulation of GPCR function and may partially contribute to functional selectivity of some GPCRs. In this review we highlight examples of PTMs located in GPCR extracellular domains, with special focus on glycosylation and the potential interplay with other close-by PTMs such as tyrosine sulfation, proteolytic cleavage, and phosphorylation.
Collapse
Affiliation(s)
- Christoffer K Goth
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, DK 2200, Denmark
| | - Ulla E Petäjä-Repo
- Medical Research Center Oulu, Research Unit of Biomedicine, University of Oulu, Oulu, FI-90014, Finland
| | - Mette M Rosenkilde
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, DK 2200, Denmark
| |
Collapse
|
5
|
Ayers K, Kumar R, Robevska G, Bruell S, Bell K, Malik MA, Bathgate RA, Sinclair A. Familial bilateral cryptorchidism is caused by recessive variants in RXFP2. J Med Genet 2019; 56:727-733. [PMID: 31167797 PMCID: PMC6860408 DOI: 10.1136/jmedgenet-2019-106203] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 05/09/2019] [Accepted: 05/10/2019] [Indexed: 11/12/2022]
Abstract
BACKGROUND Cryptorchidism or failure of testicular descent is the most common genitourinary birth defect in males. While both the insulin-like peptide 3 (INSL3) and its receptor, relaxin family peptide receptor 2 (RXFP2), have been demonstrated to control testicular descent in mice, their link to human cryptorchidism is weak, with no clear cause-effect demonstrated. OBJECTIVE To identify the genetic cause of a case of familial cryptorchidism. METHODS We recruited a family in which four boys had isolated bilateral cryptorchidism. A fourth-degree consanguineous union in the family was reported. Whole exome sequencing was carried out for the four affected boys and their parents, and variants that segregated with the disorder and had a link to testis development/descent were analysed. Functional analysis of a RXFP2 variant in cell culture included receptor localisation, ligand binding and cyclic AMP (cAMP) pathway activation. RESULTS Genomic analysis revealed a homozygous missense variant in the RXFP2 gene (c.1496G>A .p.Gly499Glu) in all four affected boys and heterozygous in both parents. No other variant with a link to testis biology was found. The RXFP2 variant is rare in genomic databases and predicted to be damaging. It has not been previously reported. Functional analysis demonstrated that the variant protein had poor cell surface expression and failed to bind INSL3 or respond to the ligand with cAMP signalling. CONCLUSION This is the first reported genomic analysis of a family with multiple individuals affected with cryptorchidism. It demonstrates that recessive variants in the RXFP2 gene underlie familial cryptorchidism and solidifies the link between this gene and testicular descent in humans.
Collapse
Affiliation(s)
- Katie Ayers
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
- Murdoch Children's Research Institute, Parkville, Melbourne, Victoria, Australia
| | - Rakesh Kumar
- Paediatric Endocrinology and Diabetes Unit, Department of Paediatric Medicine, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Gorjana Robevska
- Murdoch Children's Research Institute, Parkville, Melbourne, Victoria, Australia
| | - Shoni Bruell
- Florey Institute of Neuroscience and Mental Health, Parkville, Melbourne, Victoria, Australia
- Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Katrina Bell
- Murdoch Children's Research Institute, Parkville, Melbourne, Victoria, Australia
| | - Muneer A Malik
- Department of Paediatric Surgery, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Ross A Bathgate
- Florey Institute of Neuroscience and Mental Health, Parkville, Melbourne, Victoria, Australia
- Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Andrew Sinclair
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
- Murdoch Children's Research Institute, Parkville, Melbourne, Victoria, Australia
| |
Collapse
|
6
|
Hoare BL, Kocan M, Bruell S, Scott DJ, Bathgate RAD. Using the novel HiBiT tag to label cell surface relaxin receptors for BRET proximity analysis. Pharmacol Res Perspect 2019; 7:e00513. [PMID: 31384473 PMCID: PMC6667744 DOI: 10.1002/prp2.513] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 07/11/2019] [Accepted: 07/16/2019] [Indexed: 12/04/2022] Open
Abstract
Relaxin family peptide 1 (RXFP1) is the receptor for relaxin a peptide hormone with important therapeutic potential. Like many G protein-coupled receptors (GPCRs), RXFP1 has been reported to form homodimers. Given the complex activation mechanism of RXFP1 by relaxin, we wondered whether homodimerization may be explicitly required for receptor activation, and therefore sought to determine if there is any relaxin-dependent change in RXFP1 proximity at the cell surface. Bioluminescence resonance energy transfer (BRET) between recombinantly tagged receptors is often used in GPCR proximity studies. RXFP1 targets poorly to the cell surface when overexpressed in cell lines, with the majority of the receptor proteins sequestered within the cell. Thus, any relaxin-induced changes in RXFP1 proximity at the cell surface may be obscured by BRET signal originating from intracellular compartments. We therefore, utilized the newly developed split luciferase system called HiBiT to specifically label the extracellular terminus of cell surface RXFP1 receptors in combination with mCitrine-tagged receptors, using the GABAB heterodimer as a positive control. This demonstrated that the BRET signal detected from RXFP1-RXFP1 proximity at the cell surface does not appear to be due to stable physical interactions. The fact that there is also no relaxin-mediated change in RXFP1-RXFP1 proximity at the cell surface further supports these conclusions. This work provides a basis by which cell surface GPCR proximity and expression levels can be specifically studied using a facile and homogeneous labeling technique such as HiBiT.
Collapse
Affiliation(s)
- Bradley L. Hoare
- Florey Institute of Neuroscience and Mental Health and Florey Department of Neuroscience and Mental HealthParkvilleVictoriaAustralia
| | - Martina Kocan
- Florey Institute of Neuroscience and Mental Health and Florey Department of Neuroscience and Mental HealthParkvilleVictoriaAustralia
| | - Shoni Bruell
- Florey Institute of Neuroscience and Mental Health and Florey Department of Neuroscience and Mental HealthParkvilleVictoriaAustralia
- Department of Biochemistry and Molecular BiologyThe University of MelbourneParkvilleVictoriaAustralia
| | - Daniel J. Scott
- Florey Institute of Neuroscience and Mental Health and Florey Department of Neuroscience and Mental HealthParkvilleVictoriaAustralia
- Department of Biochemistry and Molecular BiologyThe University of MelbourneParkvilleVictoriaAustralia
| | - Ross A. D. Bathgate
- Florey Institute of Neuroscience and Mental Health and Florey Department of Neuroscience and Mental HealthParkvilleVictoriaAustralia
- Department of Biochemistry and Molecular BiologyThe University of MelbourneParkvilleVictoriaAustralia
| |
Collapse
|
7
|
Sethi A, Bruell S, Patil N, Hossain MA, Scott DJ, Petrie EJ, Bathgate RAD, Gooley PR. The complex binding mode of the peptide hormone H2 relaxin to its receptor RXFP1. Nat Commun 2016; 7:11344. [PMID: 27088579 PMCID: PMC4837482 DOI: 10.1038/ncomms11344] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 03/16/2016] [Indexed: 11/20/2022] Open
Abstract
H2 relaxin activates the relaxin family peptide receptor-1 (RXFP1), a class A G-protein coupled receptor, by a poorly understood mechanism. The ectodomain of RXFP1 comprises an N-terminal LDLa module, essential for activation, tethered to a leucine-rich repeat (LRR) domain by a 32-residue linker. H2 relaxin is hypothesized to bind with high affinity to the LRR domain enabling the LDLa module to bind and activate the transmembrane domain of RXFP1. Here we define a relaxin-binding site on the LDLa-LRR linker, essential for the high affinity of H2 relaxin for the ectodomain of RXFP1, and show that residues within the LDLa-LRR linker are critical for receptor activation. We propose H2 relaxin binds and stabilizes a helical conformation of the LDLa-LRR linker that positions residues of both the linker and the LDLa module to bind the transmembrane domain and activate RXFP1. The mechanism by which relaxin activates the relaxin family peptide receptor-1 is poorly understood. Here, Sethi et al. identify a relaxin binding site in an extracellular linker between the LDLa and LRR domains and propose that relaxin binding stabilizes a helical conformation that leads to receptor activation.
Collapse
Affiliation(s)
- Ashish Sethi
- Department of Biochemistry &Molecular Biology, The University of Melbourne, Victoria 3010, Australia.,Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Shoni Bruell
- Department of Biochemistry &Molecular Biology, The University of Melbourne, Victoria 3010, Australia.,Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia.,Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia
| | - Nitin Patil
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia.,School of Chemistry, The University of Melbourne, Victoria 3010, Australia
| | - Mohammed Akhter Hossain
- School of Chemistry, The University of Melbourne, Victoria 3010, Australia.,Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia
| | - Daniel J Scott
- Department of Biochemistry &Molecular Biology, The University of Melbourne, Victoria 3010, Australia.,Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia
| | - Emma J Petrie
- Department of Biochemistry &Molecular Biology, The University of Melbourne, Victoria 3010, Australia.,Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Ross A D Bathgate
- Department of Biochemistry &Molecular Biology, The University of Melbourne, Victoria 3010, Australia.,Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia
| | - Paul R Gooley
- Department of Biochemistry &Molecular Biology, The University of Melbourne, Victoria 3010, Australia.,Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| |
Collapse
|
8
|
Dschietzig TB, Krause-Relle K, Hennequin M, von Websky K, Rahnenführer J, Ruppert J, Grön HJ, Armbruster FP, Bathgate RAD, Aschenbach JR, Forssmann WG, Hocher B. Relaxin-2 does not ameliorate nephropathy in an experimental model of type-1 diabetes. Kidney Blood Press Res 2016; 40:77-88. [PMID: 25791819 DOI: 10.1159/000368484] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS In diabetic nephropathy (DN), the current angiotensin-II-blocking pharmacotherapy is frequently failing. For diabetic cardiomyopathy (DC), there is no specific remedy available. Relaxin-2 (Rlx) - an anti-fibrotic, anti-inflammatory, and vasoprotecting peptide – is a candidate drug for both. METHODS Low-dose (32 μg/kg/day) and high-dose (320 μg/kg/day) Rlx were tested against vehicle (n = 20 each) and non-diabetic controls (n = 14) for 12 weeks in a model of type-1 diabetes induced in endothelial nitric oxide synthase knock-out (eNOS-KO) mice by intraperitoneal injection of streptozotocin. RESULTS Diabetic animals showed normal plasma creatinine, markedly increased albuminuria and urinary malonyldialdehyde, elevated relative kidney weight, glomerulosclerosis, and increased glomerular size, but no relevant interstitial fibrosis. Neither dose of Rlx affected these changes although the drug was active and targeted plasma levels were achieved. Of note, we found no activation of the renal TGF-β pathway in this model. In the hearts of diabetic animals, no fibrotic alterations indicative of DC could be determined which precluded testing of the initial hypothesis. CONCLUSIONS We investigated a model showing early DN without overt tubulointerstitial fibrosis and activation of the TGF-β-Smad-2/3 pathway. In this model, Rlx proved ineffective; however, the same may not apply to other models and types of diabetes.
Collapse
|
9
|
Halls ML, Bathgate RAD, Sutton SW, Dschietzig TB, Summers RJ. International Union of Basic and Clinical Pharmacology. XCV. Recent advances in the understanding of the pharmacology and biological roles of relaxin family peptide receptors 1-4, the receptors for relaxin family peptides. Pharmacol Rev 2015; 67:389-440. [PMID: 25761609 DOI: 10.1124/pr.114.009472] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Relaxin, insulin-like peptide 3 (INSL3), relaxin-3, and INSL5 are the cognate ligands for the relaxin family peptide (RXFP) receptors 1-4, respectively. RXFP1 activates pleiotropic signaling pathways including the signalosome protein complex that facilitates high-sensitivity signaling; coupling to Gα(s), Gα(i), and Gα(o) proteins; interaction with glucocorticoid receptors; and the formation of hetero-oligomers with distinctive pharmacological properties. In addition to relaxin-related ligands, RXFP1 is activated by Clq-tumor necrosis factor-related protein 8 and by small-molecular-weight agonists, such as ML290 [2-isopropoxy-N-(2-(3-(trifluoromethylsulfonyl)phenylcarbamoyl)phenyl)benzamide], that act allosterically. RXFP2 activates only the Gα(s)- and Gα(o)-coupled pathways. Relaxin-3 is primarily a neuropeptide, and its cognate receptor RXFP3 is a target for the treatment of depression, anxiety, and autism. A variety of peptide agonists, antagonists, biased agonists, and an allosteric modulator target RXFP3. Both RXFP3 and the related RXFP4 couple to Gα(i)/Gα(o) proteins. INSL5 has the properties of an incretin; it is secreted from the gut and is orexigenic. The expression of RXFP4 in gut, adipose tissue, and β-islets together with compromised glucose tolerance in INSL5 or RXFP4 knockout mice suggests a metabolic role. This review focuses on the many advances in our understanding of RXFP receptors in the last 5 years, their signal transduction mechanisms, the development of novel compounds that target RXFP1-4, the challenges facing the field, and current prospects for new therapeutics.
Collapse
Affiliation(s)
- Michelle L Halls
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.L.H., R.J.S.); Neuropeptides Division, Florey Institute of Neuroscience and Mental Health and Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia (R.A.D.B.); Neuroscience Drug Discovery, Janssen Research & Development, LLC, San Diego, California (S.W.S.); Immundiagnostik AG, Bensheim, Germany (T.B.D.); and Charité-University Medicine Berlin, Campus Mitte, Medical Clinic for Cardiology and Angiology, Berlin, Germany (T.B.D.)
| | - Ross A D Bathgate
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.L.H., R.J.S.); Neuropeptides Division, Florey Institute of Neuroscience and Mental Health and Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia (R.A.D.B.); Neuroscience Drug Discovery, Janssen Research & Development, LLC, San Diego, California (S.W.S.); Immundiagnostik AG, Bensheim, Germany (T.B.D.); and Charité-University Medicine Berlin, Campus Mitte, Medical Clinic for Cardiology and Angiology, Berlin, Germany (T.B.D.)
| | - Steve W Sutton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.L.H., R.J.S.); Neuropeptides Division, Florey Institute of Neuroscience and Mental Health and Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia (R.A.D.B.); Neuroscience Drug Discovery, Janssen Research & Development, LLC, San Diego, California (S.W.S.); Immundiagnostik AG, Bensheim, Germany (T.B.D.); and Charité-University Medicine Berlin, Campus Mitte, Medical Clinic for Cardiology and Angiology, Berlin, Germany (T.B.D.)
| | - Thomas B Dschietzig
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.L.H., R.J.S.); Neuropeptides Division, Florey Institute of Neuroscience and Mental Health and Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia (R.A.D.B.); Neuroscience Drug Discovery, Janssen Research & Development, LLC, San Diego, California (S.W.S.); Immundiagnostik AG, Bensheim, Germany (T.B.D.); and Charité-University Medicine Berlin, Campus Mitte, Medical Clinic for Cardiology and Angiology, Berlin, Germany (T.B.D.)
| | - Roger J Summers
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.L.H., R.J.S.); Neuropeptides Division, Florey Institute of Neuroscience and Mental Health and Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia (R.A.D.B.); Neuroscience Drug Discovery, Janssen Research & Development, LLC, San Diego, California (S.W.S.); Immundiagnostik AG, Bensheim, Germany (T.B.D.); and Charité-University Medicine Berlin, Campus Mitte, Medical Clinic for Cardiology and Angiology, Berlin, Germany (T.B.D.)
| |
Collapse
|
10
|
Huang Z, Myhr C, Bathgate RAD, Ho BA, Bueno A, Hu X, Xiao J, Southall N, Barnaeva E, Agoulnik IU, Marugan JJ, Ferrer M, Agoulnik AI. Activation of Relaxin Family Receptor 1 from Different Mammalian Species by Relaxin Peptide and Small-Molecule Agonist ML290. Front Endocrinol (Lausanne) 2015; 6:128. [PMID: 26347712 PMCID: PMC4538381 DOI: 10.3389/fendo.2015.00128] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 07/31/2015] [Indexed: 12/12/2022] Open
Abstract
Relaxin peptide (RLN), which signals through the relaxin family peptide 1 (RXFP1) GPCR receptor, has shown therapeutic effects in an acute heart failure clinical trial. We have identified a small-molecule agonist of human RXFP1, ML290; however, it does not activate the mouse receptor. To find a suitable animal model for ML290 testing and to gain mechanistic insights into the interaction of various ligands with RXFP1, we have cloned rhesus macaque, pig, rabbit, and guinea pig RXFP1s and analyzed their activation by RLN and ML290. HEK293T cells expressing macaque or pig RXFP1 responded to relaxin and ML290 treatment as measured by an increase of cAMP production. Guinea pig RXFP1 responded to relaxin but had very low response to ML290 treatment only at highest concentrations used. The rabbit RXFP1 amino acid sequence was the most divergent, with a number of unique substitutions within the ectodomain and the seven-transmembrane domain (7TM). Two splice variants of rabbit RXFP1 derived through alternative splicing of the fourth exon were identified. In contrast to the other species, rabbit RXFP1s were activated by ML290, but not with human, pig, mouse, or rabbit RLNs. Using FLAG-tagged constructs, we have shown that both rabbit RXFP1 variants are expressed on the cell surface. No binding of human Eu-labeled RLN to rabbit RXFP1 was detected, suggesting that in this species, RXFP1 might be non-functional. We used chimeric rabbit-human and guinea pig-human constructs to identify regions important for RLN or ML290 receptor activation. Chimeras with the human ectodomain and rabbit 7TM domain were activated by RLN, whereas substitution of part of the guinea pig 7TM domain with the human sequence only partially restored ML290 activation, confirming the allosteric mode of action for the two ligands. Our data demonstrate that macaque and pig models can be used for ML290 testing.
Collapse
Affiliation(s)
- Zaohua Huang
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Courtney Myhr
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Ross A. D. Bathgate
- Department of Biochemistry and Molecular Biology, Florey Department of Neuroscience and Mental Health, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Brian A. Ho
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Amaya Bueno
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Xin Hu
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Jingbo Xiao
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Noel Southall
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Elena Barnaeva
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Irina U. Agoulnik
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Juan J. Marugan
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Marc Ferrer
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Alexander I. Agoulnik
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
- *Correspondence: Alexander I. Agoulnik, Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, 11200 SW 8th Street, AHCI 419B, Miami, FL 33199, USA,
| |
Collapse
|
11
|
Shen J, Ding Y, Gao C, Rojo E, Jiang L. N-linked glycosylation of AtVSR1 is important for vacuolar protein sorting in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 80:977-92. [PMID: 25293377 DOI: 10.1111/tpj.12696] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 09/25/2014] [Accepted: 09/25/2014] [Indexed: 05/18/2023]
Abstract
Vacuolar sorting receptors (VSRs) in Arabidopsis mediate the sorting of soluble proteins to vacuoles in the secretory pathway. The VSRs are post-translationally modified by the attachment of N-glycans, but the functional significance of such a modification remains unknown. Here we have studied the role(s) of glycosylation in the stability, trafficking and vacuolar protein transport of AtVSR1 in Arabidopsis protoplasts. AtVSR1 harbors three complex-type N-glycans, which are located in the N-terminal 'PA domain', the central region and the C-terminal epidermal growth factor repeat domain, respectively. We have demonstrated that: (i) the N-glycans do not affect the targeting of AtVSR1 to pre-vacuolar compartments (PVCs) and its vacuolar degradation; and (ii) N-glycosylation alters the binding affinity of AtVSR1 to cargo proteins and affects the transport of cargo into the vacuole. Hence, N-glycosylation of AtVSR1 plays a critical role in its function as a VSR in plants.
Collapse
Affiliation(s)
- Jinbo Shen
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | | | | | | | | |
Collapse
|
12
|
Rymen D, Jaeken J. Skin manifestations in CDG. J Inherit Metab Dis 2014; 37:699-708. [PMID: 24554337 DOI: 10.1007/s10545-014-9678-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 12/01/2013] [Accepted: 01/20/2014] [Indexed: 10/25/2022]
Abstract
The group of congenital disorders of glycosylation (CDG) has expanded tremendously since its first description in 1980, with around 70 distinct disorders described to date. A great phenotypic variability exists, ranging from multisystem disease to single organ involvement. Skin manifestations, although inconsistently present, are part of this broad clinical spectrum. Indeed, the presence of inverted nipples, fat pads and orange peel skin in a patient with developmental delay are considered as a hallmark of CDG, particularly seen in PMM2 deficiency. However, over the years many more dermatological findings have been observed (e.g., ichthyosis, cutis laxa, tumoral calcinosis…). In this review we will discuss the variety of skin manifestations reported in CDG. Moreover, we will explore the possible mechanisms that link a certain glycosylation deficiency to its skin phenotype.
Collapse
Affiliation(s)
- D Rymen
- Center for Human Genetics, University of Leuven, Leuven, Belgium,
| | | |
Collapse
|
13
|
Kong RCK, Bathgate RAD, Bruell S, Wade JD, Gooley PR, Petrie EJ. Mapping Key Regions of the RXFP2 Low-Density Lipoprotein Class-A Module That Are Involved in Signal Activation. Biochemistry 2014; 53:4537-48. [DOI: 10.1021/bi500797d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Roy C. K. Kong
- Department of Biochemistry and Molecular Biology, The Bio21 Molecular
Science and Biotechnology Institute, ‡Florey Institute of Neuroscience
and Mental Health, and §School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Ross A. D. Bathgate
- Department of Biochemistry and Molecular Biology, The Bio21 Molecular
Science and Biotechnology Institute, ‡Florey Institute of Neuroscience
and Mental Health, and §School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Shoni Bruell
- Department of Biochemistry and Molecular Biology, The Bio21 Molecular
Science and Biotechnology Institute, ‡Florey Institute of Neuroscience
and Mental Health, and §School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
| | - John D. Wade
- Department of Biochemistry and Molecular Biology, The Bio21 Molecular
Science and Biotechnology Institute, ‡Florey Institute of Neuroscience
and Mental Health, and §School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Paul R. Gooley
- Department of Biochemistry and Molecular Biology, The Bio21 Molecular
Science and Biotechnology Institute, ‡Florey Institute of Neuroscience
and Mental Health, and §School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Emma J. Petrie
- Department of Biochemistry and Molecular Biology, The Bio21 Molecular
Science and Biotechnology Institute, ‡Florey Institute of Neuroscience
and Mental Health, and §School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
| |
Collapse
|
14
|
Gubbels CS, Welt CK, Dumoulin JCM, Robben SGF, Gordon CM, Dunselman GAJ, Rubio-Gozalbo ME, Berry GT. The male reproductive system in classic galactosemia: cryptorchidism and low semen volume. J Inherit Metab Dis 2013; 36:779-86. [PMID: 23053469 DOI: 10.1007/s10545-012-9539-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 07/27/2012] [Accepted: 08/27/2012] [Indexed: 10/27/2022]
Abstract
Previous studies examining reproductive parameters in men with galactosemia have inconsistently demonstrated abnormalities. We hypothesized that men with galactosemia may demonstrate evidence of reproductive dysfunction. Pubertal history, physical examination, hormone levels and semen analyses were examined in 26 males with galactosemia and compared to those in 46 controls. The prevalence of cryptorchidism was higher in men with galactosemia than in the general population [11.6% vs. 1.0% (95%CI: 0.75-1.26; p <0.001)]. Testosterone (461±125 vs. 532± 33 ng%; p=0.04), inhibin B (144±66 vs. 183±52 pg/mL; p=0.002) and sperm concentration (46±36 vs. 112±75×10(6) spermatozoa/mL; p=0.01) were lower and SHBG was higher (40.7±21.5 vs 26.7±14.6; p=0.002) in men with galactosemia compared to controls. Semen volume was below normal in seven out of 12 men with galactosemia. Men with galactosemia have a higher than expected prevalence of cryptorchidism and low semen volumes. The subtle decrease in testosterone and inhibin B levels and sperm count may indicate mild defects in Sertoli and Leydig cell function, but does not point towards severe infertility causing reproductive impairment. Follow-up studies are needed to further determine the clinical consequences of these abnormalities.
Collapse
Affiliation(s)
- Cynthia S Gubbels
- Department of Clinical Genetics, Maastricht University Medical Center, Postbus 5800, 6202 AZ, Maastricht, The Netherlands.
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Kong RCK, Petrie EJ, Mohanty B, Ling J, Lee JCY, Gooley PR, Bathgate RAD. The relaxin receptor (RXFP1) utilizes hydrophobic moieties on a signaling surface of its N-terminal low density lipoprotein class A module to mediate receptor activation. J Biol Chem 2013; 288:28138-51. [PMID: 23926099 DOI: 10.1074/jbc.m113.499640] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The peptide hormone relaxin is showing potential as a treatment for acute heart failure. Although it is known that relaxin mediates its actions through the G protein-coupled receptor relaxin family peptide receptor 1 (RXFP1), little is known about the molecular mechanisms by which relaxin binding results in receptor activation. Previous studies have highlighted that the unique N-terminal low density lipoprotein class A (LDLa) module of RXFP1 is essential for receptor activation, and it has been hypothesized that this module is the true "ligand" of the receptor that directs the conformational changes necessary for G protein coupling. In this study, we confirmed that an RXFP1 receptor lacking the LDLa module binds ligand normally but cannot signal through any characterized G protein-coupled receptor signaling pathway. Furthermore, we comprehensively examined the contributions of amino acids in the LDLa module to RXFP1 activity using both gain-of-function and loss-of-function mutational analysis together with NMR structural analysis of recombinant LDLa modules. Gain-of-function studies with an inactive RXFP1 chimera containing the LDLa module of the human LDL receptor (LB2) demonstrated two key N-terminal regions of the module that were able to rescue receptor signaling. Loss-of-function mutations of residues in these regions demonstrated that Leu-7, Tyr-9, and Lys-17 all contributed to the ability of the LDLa module to drive receptor activation, and judicious amino acid substitutions suggested this involves hydrophobic interactions. Our results demonstrate that these key residues contribute to interactions driving the active receptor conformation, providing further evidence of a unique mode of G protein-coupled receptor activation.
Collapse
Affiliation(s)
- Roy C K Kong
- From the Florey Institute of Neuroscience and Mental Health and Florey Department of Neuroscience and Mental Health
| | | | | | | | | | | | | |
Collapse
|
16
|
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: 379] [Impact Index Per Article: 34.5] [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.
Collapse
Affiliation(s)
- R A D Bathgate
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology, Monash University, Victoria, Australia
| | | | | | | | | | | |
Collapse
|
17
|
Bathgate RAD, Oh MHY, Ling WJJ, Kaas Q, Hossain MA, Gooley PR, Rosengren KJ. Elucidation of relaxin-3 binding interactions in the extracellular loops of RXFP3. Front Endocrinol (Lausanne) 2013; 4:13. [PMID: 23440673 PMCID: PMC3579193 DOI: 10.3389/fendo.2013.00013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 01/31/2013] [Indexed: 12/28/2022] Open
Abstract
Relaxin-3 is a highly conserved neuropeptide in vertebrate species and binds to the Class A G protein-coupled receptor (GPCR) RXFP3. Relaxin-3 is involved in a wide range of behaviors, including feeding, stress responses, arousal, and cognitive processes and therefore targeting of RXFP3 may be relevant for a range of neurological diseases. Structural knowledge of RXFP3 and its interaction with relaxin-3 would both increase our understanding of ligand recognition in GPCRs that respond to protein ligands and enable acceleration of the design of drug leads. In this study we have used comparative sequence analysis, molecular modeling and receptor mutagenesis to investigate the binding site of the native ligand human relaxin-3 (H3 relaxin) on the human RXFP3 receptor. Previous structure function studies have demonstrated that arginine residues in the H3 relaxin B-chain are critical for binding interactions with the receptor extracellular loops and/or N-terminal domain. Hence we have concentrated on determining the ligand interacting sites in these domains and have focused on glutamic (E) and aspartic acid (D) residues in these regions that may form electrostatic interactions with these critical arginine residues. Conserved D/E residues identified from vertebrate species multiple sequence alignments were mutated to Ala in human RXFP3 to test the effect of loss of amino acid side chain on receptor binding using a Eu-labeled relaxin-3 agonist. Finally data from mutagenesis experiments have been used in ligand docking simulations to a homology model of human RXFP3 based on the peptide-bound chemokine receptor 4 (CXCR4) structure. These studies have resulted in a model of the relaxin-3 interaction with RXFP3 which will inform further interrogation of the agonist binding site.
Collapse
Affiliation(s)
- Ross A. D. Bathgate
- Florey Institute of Neuroscience and Mental Health, University of MelbourneParkville, VIC, Australia
- Department of Biochemistry and Molecular Biology, University of MelbourneParkville, VIC, Australia
- *Correspondence: Ross A. D. Bathgate, Florey Institute of Neuroscience and Mental Health, University of Melbourne, 3010 Victoria, Australia. e-mail:
| | - Maria H. Y. Oh
- Florey Institute of Neuroscience and Mental Health, University of MelbourneParkville, VIC, Australia
- Department of Biochemistry and Molecular Biology, University of MelbourneParkville, VIC, Australia
| | - W. J. Jason Ling
- Florey Institute of Neuroscience and Mental Health, University of MelbourneParkville, VIC, Australia
- Department of Biochemistry and Molecular Biology, University of MelbourneParkville, VIC, Australia
| | - Quentin Kaas
- Institute for Molecular Bioscience, The University of QueenslandBrisbane, QLD, Australia
| | - M. Akhter Hossain
- Florey Institute of Neuroscience and Mental Health, University of MelbourneParkville, VIC, Australia
- School of Chemistry, University of MelbourneParkville, VIC, Australia
| | - Paul R. Gooley
- Department of Biochemistry and Molecular Biology, University of MelbourneParkville, VIC, Australia
| | - K. Johan Rosengren
- School of Biomedical Sciences, The University of QueenslandBrisbane, QLD, Australia
| |
Collapse
|
18
|
Bruell S, Kong RCK, Petrie EJ, Hoare B, Wade JD, Scott DJ, Gooley PR, Bathgate RAD. Chimeric RXFP1 and RXFP2 Receptors Highlight the Similar Mechanism of Activation Utilizing Their N-Terminal Low-Density Lipoprotein Class A Modules. Front Endocrinol (Lausanne) 2013; 4:171. [PMID: 24273532 PMCID: PMC3822782 DOI: 10.3389/fendo.2013.00171] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 10/25/2013] [Indexed: 11/13/2022] Open
Abstract
Relaxin family peptide (RXFP) receptors 1 and 2 are unique G-protein coupled receptors in that they contain an N-terminal low-density lipoprotein type A (LDLa) module which is necessary for receptor activation. The current hypothesis suggests that upon ligand binding the LDLa module interacts with the transmembrane (TM) domain of a homodimer partner receptor to induce the active receptor conformations. We recently demonstrated that three residues in the N-terminus of the RXFP1 LDLa module are potentially involved in hydrophobic interactions with the receptor to drive activation. RXFP2 shares two out of three of the residues implicated, suggesting that the two LDLa modules could be interchanged without adversely affecting activity. However, in 2007 it was shown that a chimera consisting of the RXFP1 receptor with its LDLa swapped for that of RXFP2 did not signal. We noticed this construct also contained the RXFP2 region linking the LDLa to the leucine-rich repeats. We therefore constructed chimeric RXFP1 and RXFP2 receptors with their LDLa modules swapped immediately C-terminally to the final cysteine residue of the module, retaining the native linker. In addition, we exchanged the TM domains of the chimeras to explore if matching the LDLa module with the TM domain of its native receptor altered activity. All of the chimeras were expressed at the surface of HEK293T cells with ligand binding profiles similar to the wild-type receptors. Importantly, as predicted, ligand binding was able to induce cAMP-based signaling. Chimeras of RXFP1 with the LDLa of RXFP2 demonstrated reduced H2 relaxin potency with the pairing of the RXFP2 TM with the RXFP2 LDLa necessary for full ligand efficacy. In contrast the ligand-mediated potencies and efficacies on the RXFP2 chimeras were similar suggesting the RXFP1 LDLa module has similar efficacy on the RXFP2 TM domain. Our studies demonstrate the LDLa modules of RXFP1 and RXFP2 modulate receptor activation via a similar mechanism.
Collapse
Affiliation(s)
- Shoni Bruell
- Florey Department of Neuroscience and Mental Health, Florey Institute of Neuroscience and Mental Health , Melbourne, VIC , Australia ; Department of Biochemistry and Molecular Biology , Melbourne, VIC , Australia
| | | | | | | | | | | | | | | |
Collapse
|
19
|
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.
Collapse
Affiliation(s)
- Daniel J Scott
- Florey Neuroscience Institutes and the Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | | | | |
Collapse
|
20
|
Donizetti A, Fiengo M, del Gaudio R, Di Giaimo R, Minucci S, Aniello F. Characterization and developmental expression pattern of the relaxin receptor rxfp1 gene in zebrafish. Dev Growth Differ 2011; 52:799-806. [PMID: 21158758 DOI: 10.1111/j.1440-169x.2010.01215.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We report the gene characterization, the cDNA cloning and the temporal and spatial expression pattern of the relaxin receptor rxfp1 gene in the zebrafish Danio rerio. The zebrafish rxfp1 gene has the same syntenic genomic organization, and a similar exon-intron structure to the homologue human gene. Furthermore, the deduced Rxfp1 protein sequence shows a high degree of amino acid similarity when compared with the human protein and the conservation of all amino acid identity necessary for the binding with relaxin. Our results show that rxfp1 gene is active either during embryogenesis or in the adult organism, showing a wide expression pattern. Moreover, we provide the first description of rxfp1 spatial expression pattern during embryo development, showing that the transcript is already present at the early developmental stage and is distributed in all of the embryonic cells until somitogenesis. Starting at the pharyngula stage the gene expression becomes mainly restricted in the brain territories. In fact, at the larval stage, the transcript is detectable in the epiphysis, postoptic region, posterior tuberculum, hypothalamus, optic tectum, tegmentum/pons, medulla and also in the structure of a peripheral nervous system, the terminal nerve. The rxfp1 expression pattern in Danio rerio embryos is very similar to that reported in the adult mammalian brain, suggesting a pivotal role of this receptor in the neurophysiology processes already at very early developmental stages.
Collapse
Affiliation(s)
- Aldo Donizetti
- Department of Biological Sciences, University of Naples Federico II, Via Mezzocannone 8, Napoli, Italy
| | | | | | | | | | | |
Collapse
|
21
|
Feugang JM, Rodriguez-Munoz JC, Willard ST, Bathgate RA, Ryan PL. Examination of relaxin and its receptors expression in pig gametes and embryos. Reprod Biol Endocrinol 2011; 9:10. [PMID: 21251292 PMCID: PMC3032664 DOI: 10.1186/1477-7827-9-10] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 01/20/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Relaxin is a small peptide also known as pregnancy hormone in many mammals. It is synthesized by both male and female tissues, and its secretions are found in various body fluids such as plasma serum, ovarian follicular fluid, utero-oviduct secretions, and seminal plasma of many mammals, including pigs. However, the presence and effects of relaxin in porcine gametes and embryos are still not well-known. The purpose of this study was to assess the presence of relaxin and its receptors RXFP1 and RXFP2 in pig gametes and embryos. METHODS Immature cumulus-oocyte complexes (COCs) were aspirated from sows' ovaries collected at the abattoir. After in vitro-maturation, COCs were in vitro-fertilized and cultured. For studies, immature and mature COCs were separately collected, and oocytes were freed from their surrounding cumulus cells. Denuded oocytes, cumulus cells, mature boar spermatozoa, zygotes, and embryos (cleaved and blastocysts) were harvested for temporal and spatial gene expression studies. Sections of ovary, granulosa and neonatal porcine uterine cells were also collected to use as controls. RESULTS Using both semi-quantitative and quantitative PCRs, relaxin transcripts were not detected in all tested samples, while RXFP1 and RXFP2 mRNA were present. Both receptor gene products were found at higher levels in oocytes compared to cumulus cells, irrespective of the maturation time. Cleaved-embryos contained higher levels of RXFP2 mRNA, whereas, blastocysts were characterized by a higher RXFP1 mRNA content. Using western-immunoblotting or in situ immunofluorescence, relaxin and its receptor proteins were detected in all samples. Their fluorescence intensities were consistently more important in mature oocytes than immature ones. The RXFP1 and RXFP2 signal intensities were mostly located in the plasma membrane region, while the relaxin ones appeared homogeneously distributed within the oocytes and embryonic cells. Furthermore, spermatozoa displayed stronger RXFP2 signal than RXFP1 after western-immunoblotting. CONCLUSION All together, our findings suggest potential roles of relaxin and its receptors during oocyte maturation, early embryo development, and beyond.
Collapse
Affiliation(s)
- Jean M Feugang
- Department of Animal & Dairy Sciences, Mississippi State University, 4025 Wise Center, Mississippi State, MS 38762, USA
| | - Juan C Rodriguez-Munoz
- Department of Animal & Dairy Sciences, Mississippi State University, 4025 Wise Center, Mississippi State, MS 38762, USA
| | - Scott T Willard
- Department of Biochemistry & Molecular Biology, Mississippi State University, 402 Dorman Hall, Mississippi, MS 38762, USA
| | - Ross A Bathgate
- Florey Neuroscience Institutes, University of Melbourne, Gate 11, Royal Parade, Victoria, 3010, Australia
| | - Peter L Ryan
- Department of Animal & Dairy Sciences, Mississippi State University, 4025 Wise Center, Mississippi State, MS 38762, USA
- Department of Pathobiology & Population Medicine, Mississippi State University, 240 Wise Center Dr., Mississippi State, MS 38762, USA
| |
Collapse
|
22
|
A missense mutation in LRR8 of RXFP2 is associated with cryptorchidism. Mamm Genome 2010; 21:442-9. [DOI: 10.1007/s00335-010-9291-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Accepted: 09/20/2010] [Indexed: 01/29/2023]
|
23
|
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.
Collapse
Affiliation(s)
- Roy C K Kong
- Florey Neuroscience Institutes, University of Melbourne, Victoria 3010, Australia
| | | | | | | | | |
Collapse
|
24
|
Pomicter AD, Shroff SM, Fuss B, Sato-Bigbee C, Brophy PJ, Rasband MN, Bhat MA, Dupree JL. Novel forms of neurofascin 155 in the central nervous system: alterations in paranodal disruption models and multiple sclerosis. Brain 2010; 133:389-405. [PMID: 20129933 PMCID: PMC2822635 DOI: 10.1093/brain/awp341] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 12/14/2009] [Accepted: 12/16/2009] [Indexed: 01/08/2023] Open
Abstract
Stability of the myelin-axon unit is achieved, at least in part, by specialized paranodal junctions comprised of the neuronal heterocomplex of contactin and contactin-associated protein and the myelin protein neurofascin 155. In multiple sclerosis, normal distribution of these proteins is altered, resulting in the loss of the insulating myelin and consequently causing axonal dysfunction. Previously, this laboratory reported that mice lacking the myelin-enriched lipid sulphatide are characterized by a progressive deterioration of the paranodal structure. Here, it is shown that this deterioration is preceded by significant loss of neurofascin 155 clustering at the myelin paranode. Interestingly, prolonged electrophoretic separation revealed the existence of two neurofascin 155 bands, neurofascin 155 high and neurofascin 155 low, which are readily observed following N-linked deglycosylation. Neurofascin 155 high is observed at 7 days of age and reaches peak expression at one month of age, while neurofascin 155 low is first observed at 14 days of age and constantly increases until 5 months of age. Studies using conditional neurofascin knockout mice indicated that neurofascin 155 high and neurofascin 155 low are products of the neurofascin gene and are exclusively expressed by oligodendrocytes within the central nervous system. Neurofascin 155 high is a myelin paranodal protein while the distribution of neurofascin 155 low remains to be determined. While neurofascin 155 high levels are significantly reduced in the sulphatide null mice at 15 days, 30 days and 4 months of age, neurofascin 155 low levels remain unaltered. Although maintained at normal levels, neurofascin 155 low is incapable of preserving paranodal structure, thus indicating that neurofascin 155 high is required for paranodal stability. Additionally, comparisons between neurofascin 155 high and neurofascin 155 low in human samples revealed a significant alteration, specifically in multiple sclerosis plaques.
Collapse
Affiliation(s)
- Anthony D. Pomicter
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
| | - Seema M. Shroff
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
| | - Babette Fuss
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
| | - Carmen Sato-Bigbee
- 2 Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, School of Medicine, Richmond, Virginia, USA
| | - Peter J. Brophy
- 3 Centre for Neuroscience Research, University of Edinburgh, Edinburgh, Scotland, UK
| | - Matthew N. Rasband
- 4 Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
| | - Manzoor A. Bhat
- 5 Department of Cell and Molecular Physiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Jeffrey L. Dupree
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
| |
Collapse
|
25
|
Kern A, Bryant-Greenwood GD. Mechanisms of relaxin receptor (LGR7/RXFP1) expression and function. Ann N Y Acad Sci 2009; 1160:60-6. [PMID: 19416160 DOI: 10.1111/j.1749-6632.2008.03826.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The LGR7/RXFP1 and LGR8/RXFP2 receptors are unique receptors among the G-protein-coupled receptors (GPCRs) in having a low-density lipoprotein class A (LDL-A) module. Their complex gene organization, among the intron-richest of the GPCRs, suggests that alternative splicing is a common occurrence. We have therefore investigated the role of the LDL-A module and shown the identity, expression, and functions of three LGR7 splice variants in the human decidua. Point mutations of conserved residues or complete deletion of the LDL-A module resulted in loss of the cAMP response to relaxin. Its glycosylation also impacted LGR7 cell surface delivery and therefore receptor activation. The wild-type (WT) LGR7 was expressed as both precursor and mature forms, but deletion of the LDL-A module resulted in expression of only the mature form. Three new alternatively spliced variants of LGR7 were identified, all containing a truncated extracellular region. Their functional characterization showed them exerting dominant negative effects on the WT LGR7 by preventing its homodimerization, maturation, and subsequent trafficking to the cell surface, resulting in loss of function. In summary, different mechanisms have been identified for controlling the cell surface expression and function of the LGR7 protein which are likely to be significant for the role of relaxin in human parturition.
Collapse
Affiliation(s)
- András Kern
- The Pacific Biosciences Research Center, University of Hawaii, Honolulu, Hawaii 96822, USA.
| | | |
Collapse
|
26
|
Hartley BJ, Scott DJ, Callander GE, Wilkinson TN, Ganella DE, Kong CK, Layfield S, Ferraro T, Petrie EJ, Bathgate RAD. Resolving the Unconventional Mechanisms Underlying RXFP1 and RXFP2 Receptor Function. Ann N Y Acad Sci 2009; 1160:67-73. [DOI: 10.1111/j.1749-6632.2009.03949.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
27
|
Callander GE, Thomas WG, Bathgate RAD. Prolonged RXFP1 and RXFP2 signaling can be explained by poor internalization and a lack of beta-arrestin recruitment. Am J Physiol Cell Physiol 2009; 296:C1058-66. [PMID: 19279230 DOI: 10.1152/ajpcell.00581.2008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Relaxin induces sustained physiological responses, which brings into question the deactivation processes typical of most G protein-coupled receptors (GPCR) for its receptor, relaxin family peptide receptor 1 (RXFP1). Here, we examined relaxin-dependent phosphorylation of RXFP1 and the related insulin-like peptide 3 (INSL3) receptor, RXFP2, as well as the capacity of these receptors to recruit beta-arrestins and internalize in response to ligand stimulation. We confirmed in human embryonic kidney (HEK)-293T cells, expressing RXFP1 or RXFP2, that both receptors elicit prolonged cAMP responses up to 6 h after stimulation. Receptors immunoprecipitated from (32)P metabolically labeled cells were used to investigate the agonist-specific phosphorylation. Rapid and robust receptor phosphorylation was not observed for either RXFP1 or RXFP2, although some (32)P-incorporation was observed at 30 min; however, this was not statistically significant. In accord with this result, RXFP1 and RXFP2 demonstrated poor internalization in response to relaxin or INSL3, as compared with the angiotensin II type 1 receptor (AT(1)R), which undergoes rapid and robust phosphorylation and internalization in response to angiotensin II. Additionally, coexpression of GPCR kinases has no effect on the rate of internalization for either RXFP1 or RXFP2. Confocal microscopy was used to follow the trafficking of green fluorescent protein-labeled beta-arrestins after receptor activation. Neither RXFP1 nor RXFP2 activation results in recruitment of beta-arrestins to the cell surface, whereas AT(1)R rapidly recruits both beta-arrestins-1 and -2. The apparent lack of classical regulation for RXFP1 and RXFP2 provides the molecular basis for the prolonged signaling and physiological actions of relaxin and related peptides.
Collapse
|
28
|
Skropeta D. The effect of individual N-glycans on enzyme activity. Bioorg Med Chem 2009; 17:2645-53. [PMID: 19285412 DOI: 10.1016/j.bmc.2009.02.037] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2008] [Revised: 02/11/2009] [Accepted: 02/13/2009] [Indexed: 01/08/2023]
Abstract
In a series of investigations, N-glycosylation has proven to be a key determinant of enzyme secretion, activity, binding affinity and substrate specificity, enabling a protein to fine-tune its activity. In the majority of cases elimination of all putative N-glycosylation sites of an enzyme results in significantly reduced protein secretion levels, while removal of individual N-glycosylation sites often leads to the expression of active enzymes showing markedly reduced catalytic activity, with the decreased activity often commensurate with the number of glycosylation sites available, and the fully deglycosylated enzymes showing only minimal activity relative to their glycosylated counterparts. On the other hand, several cases have also recently emerged where deglycosylation of an enzyme results in significantly increased catalytic activity, binding affinity and altered substrate specificity, highlighting the very unique and diverse roles that individual N-glycans play in regulating enzyme function.
Collapse
Affiliation(s)
- Danielle Skropeta
- School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.
| |
Collapse
|