1
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Wieteska Ł, Taylor AB, Punch E, Coleman JA, Conway IO, Lin YF, Byeon CH, Hinck CS, Krzysiak T, Ishima R, López-Casillas F, Cherepanov P, Bernard DJ, Hill CS, Hinck AP. Structures of TGF-β with betaglycan and the signaling receptors reveal the mechanism whereby betaglycan potentiates receptor complex assembly and signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.19.604101. [PMID: 39091787 PMCID: PMC11291015 DOI: 10.1101/2024.07.19.604101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Betaglycan (BG) is a transmembrane co-receptor of the transforming growth factor-β (TGF-β) family of signaling ligands. It is essential for embryonic development and tissue homeostasis and fertility in adults. It functions by enabling binding of the three TGF-β isoforms to their signaling receptors and is additionally required for inhibin A (InhA) activity. Despite its requirement for the functions of TGF-βs and InhA in vivo, structural information explaining BG ligand selectivity and its mechanism of action is lacking. Here, we determine the structure of TGF-β bound both to BG and the signaling receptors, TGFBR1 and TGFBR2. We identify key regions responsible for ligand engagement, which has revealed novel binding interfaces that differ from those described for the closely related co-receptor of the TGF-β family, endoglin, thus demonstrating remarkable evolutionary adaptation to enable ligand selectivity. Finally, we provide a structural explanation for the hand-off mechanism underlying TGF-β signal potentiation.
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2
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Han X, Xia X, Chen W, Meng F, Cao X, Bu G, Gan T, Du X, Liang Q, Zeng X. Efficacy of Immunization against a Novel Synthetic 13-Amino Acid Betaglycan-Binding Peptide Sequence of Inhibin α Subunit on Promoting Fertility in Female Rats. Int J Mol Sci 2023; 24:ijms24086914. [PMID: 37108077 PMCID: PMC10138769 DOI: 10.3390/ijms24086914] [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: 02/21/2023] [Revised: 03/30/2023] [Accepted: 04/04/2023] [Indexed: 04/29/2023] Open
Abstract
Inhibins suppress the FSH production in pituitary gonadotrope cells by robustly antagonizing activin signaling by competitively binding to activin type II receptors (ACTR II). The binding of inhibin A to ACTR II requires the presence of its co-receptor, namely, betaglycan. In humans, the critical binding site for betaglycan to inhibin A was identified on the inhibin α subunit. Through conservation analysis, we found that a core 13-amino-acid peptide sequence <VRTTSDGGYSFKY> within the betaglycan-binding epitope on human inhibin α subunit is highly conserved across species. Based on the tandem sequence of such a conserved 13-amino-acid betaglycan-binding epitope (INHα13AA-T), we developed a novel inhibin vaccine and tested its efficacy in promoting female fertility using the female rat as a model. Compared with placebo-immunized controls, INHα13AA-T immunization induced a marked (p < 0.05) antibody generation, enhanced (p < 0.05) ovarian follicle development, and increased ovulation rate and litter sizes. Mechanistically, INHα13AA-T immunization promoted (p < 0.05) pituitary Fshb transcription and increased (p < 0.05) serum FSH and 17β-estradiol concentrations. In summary, active immunization against INHα13AA-T potently increased FSH levels, ovarian follicle development, ovulation rate and litter sizes, thus causing super-fertility in females. Therefore, immunization against INHα13AA is a promising alternative to the conventional approach of multiple ovulation and super-fertility in mammals.
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Affiliation(s)
- Xingfa Han
- Isotope Research Lab, College of Life Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Xue Xia
- Isotope Research Lab, College of Life Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Weihao Chen
- Isotope Research Lab, College of Life Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Fengyan Meng
- Isotope Research Lab, College of Life Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Xiaohan Cao
- Isotope Research Lab, College of Life Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Guixian Bu
- Isotope Research Lab, College of Life Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Tian Gan
- Isotope Research Lab, College of Life Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Xiaogang Du
- Isotope Research Lab, College of Life Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Qiuxia Liang
- Isotope Research Lab, College of Life Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Xianyin Zeng
- Isotope Research Lab, College of Life Science, Sichuan Agricultural University, Ya'an 625014, China
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3
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Review: Role and regulatory mechanism of inhibin in animal reproductive system. Theriogenology 2023; 202:10-20. [PMID: 36878034 DOI: 10.1016/j.theriogenology.2023.02.016] [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: 06/24/2022] [Revised: 02/14/2023] [Accepted: 02/15/2023] [Indexed: 03/03/2023]
Abstract
Inhibin (INH) is a glycoprotein hormone secreted by the gonads that inhibit the synthesis and secretion of follicle-stimulating hormone (FSH). Increasing evidence indicates that INH plays a significant role in the development of the reproductive system including follicle development, ovulation rate, corpus luteum formation and ablation, steroid hormone synthesis and spermatogenesis, subsequently affecting the reproductive capacity of animals such as litter size and egg production. There are currently three main views on how INH inhibits FSH synthesis and secretion: influencing the activity of adenylate cyclase, the expression of follicle-stimulating hormone receptor or gonadotropin-releasing hormone receptor, and the competition system of inhibin-activin. This review discusses the current findings on the structure, function, and mechanism of action of INH in the reproductive system of animals.
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4
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Walton KL, Goney MP, Peppas Z, Stringer JM, Winship A, Hutt K, Goodchild G, Maskey S, Chan KL, Brûlé E, Bernard DJ, Stocker WA, Harrison CA. Inhibin Inactivation in Female Mice Leads to Elevated FSH Levels, Ovarian Overstimulation, and Pregnancy Loss. Endocrinology 2022; 163:6543938. [PMID: 35255139 PMCID: PMC9272799 DOI: 10.1210/endocr/bqac025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Indexed: 11/21/2022]
Abstract
Inhibins are members of the transforming growth factor-β family, composed of a common α-subunit disulfide-linked to 1 of 2 β-subunits (βA in inhibin A or βB in inhibin B). Gonadal-derived inhibin A and B act in an endocrine manner to suppress the synthesis of follicle-stimulating hormone (FSH) by pituitary gonadotrope cells. Roles for inhibins beyond the pituitary, however, have proven difficult to delineate because deletion of the inhibin α-subunit gene (Inha) results in unconstrained expression of activin A and activin B (homodimers of inhibin β-subunits), which contribute to gonadal tumorigenesis and lethal cachectic wasting. Here, we generated mice with a single point mutation (Arg233Ala) in Inha that prevents proteolytic processing and the formation of bioactive inhibin. In vitro, this mutation blocked inhibin maturation and bioactivity, without perturbing activin production. Serum FSH levels were elevated 2- to 3-fold in InhaR233A/R233A mice due to the loss of negative feedback from inhibins, but no pathological increase in circulating activins was observed. While inactivation of inhibin A and B had no discernible effect on male reproduction, female InhaR233A/R233A mice had increased FSH-dependent follicle development and enhanced natural ovulation rates. Nevertheless, inhibin inactivation resulted in significant embryo-fetal resorptions and severe subfertility and was associated with disrupted maternal ovarian function. Intriguingly, heterozygous Inha+/R233A females had significantly enhanced fecundity, relative to wild-type littermates. These studies have revealed novel effects of inhibins in the establishment and maintenance of pregnancy and demonstrated that partial inactivation of inhibin A/B is an attractive approach for enhancing female fertility.
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Affiliation(s)
- Kelly L Walton
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
- Correspondence: Kelly L Walton, PhD, School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia 4072.
| | - Monica P Goney
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Zoe Peppas
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Jessica M Stringer
- Department of Anatomy and Developmental Biology Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Amy Winship
- Department of Anatomy and Developmental Biology Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Karla Hutt
- Department of Anatomy and Developmental Biology Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Georgia Goodchild
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Shreya Maskey
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Karen L Chan
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Emilie Brûlé
- Department of Anatomy and Cell Biology, McGill University, Montreal, Canada
| | - Daniel J Bernard
- Department of Anatomy and Cell Biology, McGill University, Montreal, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - William A Stocker
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
- Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Australia
| | - Craig A Harrison
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
- Correspondence: Craig A Harrison, PhD, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia 3168.
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5
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Woodruff TK. Closing the loop on female fertility. SCIENCE ADVANCES 2021; 7:eabn1373. [PMID: 34910506 PMCID: PMC11323799 DOI: 10.1126/sciadv.abn1373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 11/22/2021] [Indexed: 06/14/2023]
Abstract
Discovery of a previously unidentified pituitary protein could provide innovative therapeutic options to regulate female fertility.
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Affiliation(s)
- Teresa K Woodruff
- Department of Obstetrics and Gynecology and Department of Biomedical Engineering, Michigan State University, East Lansing, MI, USA.
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6
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Brûlé E, Wang Y, Li Y, Lin YF, Zhou X, Ongaro L, Alonso CAI, Buddle ERS, Schneyer AL, Byeon CH, Hinck CS, Mendelev N, Russell JP, Cowan M, Boehm U, Ruf-Zamojski F, Zamojski M, Andoniadou CL, Sealfon SC, Harrison CA, Walton KL, Hinck AP, Bernard DJ. TGFBR3L is an inhibin B co-receptor that regulates female fertility. SCIENCE ADVANCES 2021; 7:eabl4391. [PMID: 34910520 PMCID: PMC8673766 DOI: 10.1126/sciadv.abl4391] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 10/19/2021] [Indexed: 06/14/2023]
Abstract
Follicle-stimulating hormone (FSH), a key regulator of ovarian function, is often used in infertility treatment. Gonadal inhibins suppress FSH synthesis by pituitary gonadotrope cells. The TGFβ type III receptor, betaglycan, is required for inhibin A suppression of FSH. The inhibin B co-receptor was previously unknown. Here, we report that the gonadotrope-restricted transmembrane protein, TGFBR3L, is the elusive inhibin B co-receptor. TGFBR3L binds inhibin B but not other TGFβ family ligands. TGFBR3L knockdown or overexpression abrogates or confers inhibin B activity in cells. Female Tgfbr3l knockout mice exhibit increased FSH levels, ovarian follicle development, and litter sizes. In contrast, female mice lacking both TGFBR3L and betaglycan are infertile. TGFBR3L’s function and cell-specific expression make it an attractive new target for the regulation of FSH and fertility.
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Affiliation(s)
- Emilie Brûlé
- Department of Anatomy and Cell Biology, McGill University, Montreal, Québec, Canada
| | - Ying Wang
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Québec, Canada
| | - Yining Li
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Québec, Canada
| | - Yeu-Farn Lin
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Québec, Canada
| | - Xiang Zhou
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Québec, Canada
| | - Luisina Ongaro
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Québec, Canada
| | - Carlos A. I. Alonso
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Québec, Canada
| | - Evan R. S. Buddle
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Québec, Canada
| | | | - Chang-Hyeock Byeon
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Cynthia S. Hinck
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Natalia Mendelev
- Department of Neurology, Center for Advanced Research on Diagnostic Assays, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - John P. Russell
- Centre for Craniofacial and Regenerative Biology, King’s College London, London, UK
| | - Mitra Cowan
- McGill Integrated Core for Animal Modeling (MICAM), McGill University, Montreal, Québec, Canada
| | - Ulrich Boehm
- Department of Experimental Pharmacology, Center for Molecular Signaling, Saarland University School of Medicine, Homburg, Germany
| | - Frederique Ruf-Zamojski
- Department of Neurology, Center for Advanced Research on Diagnostic Assays, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Michel Zamojski
- Department of Neurology, Center for Advanced Research on Diagnostic Assays, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Cynthia L. Andoniadou
- Centre for Craniofacial and Regenerative Biology, King’s College London, London, UK
- Department of Medicine III, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Stuart C. Sealfon
- Department of Neurology, Center for Advanced Research on Diagnostic Assays, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Craig A. Harrison
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Kelly L. Walton
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Andrew P. Hinck
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Daniel J. Bernard
- Department of Anatomy and Cell Biology, McGill University, Montreal, Québec, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Québec, Canada
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7
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Listik E, Horst B, Choi AS, Lee NY, Győrffy B, Mythreye K. A bioinformatic analysis of the inhibin-betaglycan-endoglin/CD105 network reveals prognostic value in multiple solid tumors. PLoS One 2021; 16:e0249558. [PMID: 33819300 PMCID: PMC8021191 DOI: 10.1371/journal.pone.0249558] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 03/21/2021] [Indexed: 12/13/2022] Open
Abstract
Inhibins and activins are dimeric ligands belonging to the TGFβ superfamily with emergent roles in cancer. Inhibins contain an α-subunit (INHA) and a β-subunit (either INHBA or INHBB), while activins are mainly homodimers of either βA (INHBA) or βB (INHBB) subunits. Inhibins are biomarkers in a subset of cancers and utilize the coreceptors betaglycan (TGFBR3) and endoglin (ENG) for physiological or pathological outcomes. Given the array of prior reports on inhibin, activin and the coreceptors in cancer, this study aims to provide a comprehensive analysis, assessing their functional prognostic potential in cancer using a bioinformatics approach. We identify cancer cell lines and cancer types most dependent and impacted, which included p53 mutated breast and ovarian cancers and lung adenocarcinomas. Moreover, INHA itself was dependent on TGFBR3 and ENG/CD105 in multiple cancer types. INHA, INHBA, TGFBR3, and ENG also predicted patients' response to anthracycline and taxane therapy in luminal A breast cancers. We also obtained a gene signature model that could accurately classify 96.7% of the cases based on outcomes. Lastly, we cross-compared gene correlations revealing INHA dependency to TGFBR3 or ENG influencing different pathways themselves. These results suggest that inhibins are particularly important in a subset of cancers depending on the coreceptor TGFBR3 and ENG and are of substantial prognostic value, thereby warranting further investigation.
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Affiliation(s)
- Eduardo Listik
- Department of Pathology, Division of Molecular and Cellular Pathology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Ben Horst
- Department of Pathology, Division of Molecular and Cellular Pathology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, United States of America
| | - Alex Seok Choi
- Department of Pathology, Division of Molecular and Cellular Pathology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Nam. Y. Lee
- Division of Pharmacology, Chemistry and Biochemistry, College of Medicine, University of Arizona, Tucson, Arizona, United States of America
| | - Balázs Győrffy
- TTK Cancer Biomarker Research Group, Institute of Enzymology, and Semmelweis University Department of Bioinformatics and 2nd Department of Pediatrics, Budapest, Hungary
| | - Karthikeyan Mythreye
- Department of Pathology, Division of Molecular and Cellular Pathology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
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8
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Bernard DJ, Smith CL, Brûlé E. A Tale of Two Proteins: Betaglycan, IGSF1, and the Continuing Search for the Inhibin B Receptor. Trends Endocrinol Metab 2020; 31:37-45. [PMID: 31648935 DOI: 10.1016/j.tem.2019.08.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 08/28/2019] [Accepted: 08/29/2019] [Indexed: 11/23/2022]
Abstract
Inhibins are gonadal hormones that suppress follicle-stimulating hormone (FSH) synthesis by pituitary gonadotrope cells. The structurally related activins stimulate FSH by signaling through complexes of type I and type II receptors. Two models of inhibin action were proposed in 2000. First, inhibins function as competitive receptor antagonists, binding activin type II receptors with high affinity in the presence of the TGF-β type III coreceptor, betaglycan. Second, immunoglobulin superfamily, member 1 (IGSF1, then called p120) was proposed to mediate inhibin B antagonism of activin signaling via its type I receptor. These ideas have been challenged over the past few years. Rather than playing a role in inhibin action, IGSF1 is involved in the central control of the thyroid gland. Betaglycan binds inhibin A and inhibin B with high affinity, but only functions as an obligate inhibin A coreceptor in murine gonadotropes. There is likely to be a distinct, but currently unidentified coreceptor for inhibin B.
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Affiliation(s)
- Daniel J Bernard
- Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada, H3G 1Y6; Department of Anatomy and Cell Biology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada, H3G 1Y6.
| | - Courtney L Smith
- Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada, H3G 1Y6
| | - Emilie Brûlé
- Department of Anatomy and Cell Biology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada, H3G 1Y6
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9
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Kim SK, Henen MA, Hinck AP. Structural biology of betaglycan and endoglin, membrane-bound co-receptors of the TGF-beta family. Exp Biol Med (Maywood) 2019; 244:1547-1558. [PMID: 31601110 PMCID: PMC6920675 DOI: 10.1177/1535370219881160] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Betaglycan and endoglin, membrane-bound co-receptors of the TGF-β family, are required to mediate the signaling of a select subset of TGF-β family ligands, TGF-β2 and InhA, and BMP-9 and BMP-10, respectively. Previous biochemical and biophysical methods suggested alternative modes of ligand binding might be responsible for these co-receptors to selectively recognize and potentiate the functions of their ligands, yet the molecular details were lacking. Recent progress determining structures of betaglycan and endoglin, both alone and as bound to their cognate ligands, is presented herein. The structures reveal relatively minor, but very significant structural differences that lead to entirely different modes of ligand binding. The different modes of binding nonetheless share certain commonalities, such as multivalency, which imparts the co-receptors with very high affinity for their cognate ligands, but at the same time provides a mechanism for release by stepwise binding of the signaling receptors, both of which are essential for their functions.
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Affiliation(s)
- Sun Kyung Kim
- Department of Structural Biology, University of Pittsburgh,
Pittsburgh, PA 15260, USA
- Department of Biochemistry and Biophysics, University California
San Francisco, San Francisco, CA 94158, USA
| | - Morkos A Henen
- Department of Structural Biology, University of Pittsburgh,
Pittsburgh, PA 15260, USA
- Faculty of Pharmacy, Mansoura University, Mansoura 35516,
Egypt
| | - Andrew P Hinck
- Department of Structural Biology, University of Pittsburgh,
Pittsburgh, PA 15260, USA
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10
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Henen MA, Mahlawat P, Zwieb C, Kodali RB, Hinck CS, Hanna RD, Krzysiak TC, Ilangovan U, Cano KE, Hinck G, Vonberg M, McCabe M, Hinck AP. TGF-β2 uses the concave surface of its extended finger region to bind betaglycan's ZP domain via three residues specific to TGF-β and inhibin-α. J Biol Chem 2019; 294:3065-3080. [PMID: 30598510 PMCID: PMC6398128 DOI: 10.1074/jbc.ra118.005210] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 12/04/2018] [Indexed: 01/17/2023] Open
Abstract
Betaglycan (BG) is a membrane-bound co-receptor of the TGF-β family that selectively binds transforming growth factor-β (TGF-β) isoforms and inhibin A (InhA) to enable temporal-spatial patterns of signaling essential for their functions in vivo Here, using NMR titrations of methyl-labeled TGF-β2 with BG's C-terminal binding domain, BGZP-C, and surface plasmon resonance binding measurements with TGF-β2 variants, we found that the BGZP-C-binding site on TGF-β2 is located on the inner surface of its extended finger region. Included in this binding site are Ile-92, Lys-97, and Glu-99, which are entirely or mostly specific to the TGF-β isoforms and the InhA α-subunit, but they are unconserved in other TGF-β family growth factors (GFs). In accord with the proposed specificity-determining role of these residues, BG bound bone morphogenetic protein 2 (BMP-2) weakly or not at all, and TGF-β2 variants with the corresponding residues from BMP-2 bound BGZP-C more weakly than corresponding alanine variants. The BGZP-C-binding site on InhA previously was reported to be located on the outside of the extended finger region, yet at the same time to include Ser-112 and Lys-119, homologous to TGF-β2 Ile-92 and Lys-97, on the inside of the fingers. Therefore, it is likely that both TGF-β2 and InhA bind BGZP-C through a site on the inside of their extended finger regions. Overall, these results identify the BGZP-C-binding site on TGF-β2 and shed light on the specificity of BG for select TGF-β-type GFs and the mechanisms by which BG influences their signaling.
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Affiliation(s)
- Morkos A Henen
- From the Departments of Structural Biology and
- the Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900
| | - Pardeep Mahlawat
- From the Departments of Structural Biology and
- the Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900
| | - Christian Zwieb
- the Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900
| | | | - Cynthia S Hinck
- From the Departments of Structural Biology and
- the Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900
| | - Ramsey D Hanna
- Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 and
| | | | - Udayar Ilangovan
- the Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900
| | - Kristin E Cano
- the Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900
| | - Garrett Hinck
- From the Departments of Structural Biology and
- the Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900
| | - Machell Vonberg
- the Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900
| | - Megan McCabe
- the Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900
| | - Andrew P Hinck
- From the Departments of Structural Biology and
- the Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900
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11
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Walton KL, Harrison CA. Inhibin: To Betaglycan, or Not to Betaglycan. Endocrinology 2019; 160:341-342. [PMID: 30576440 DOI: 10.1210/en.2018-01049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 12/16/2018] [Indexed: 11/19/2022]
Affiliation(s)
- Kelly L Walton
- Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Craig A Harrison
- Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
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12
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Li Y, Fortin J, Ongaro L, Zhou X, Boehm U, Schneyer A, Bernard DJ, Lin HY. Betaglycan (TGFBR3) Functions as an Inhibin A, but Not Inhibin B, Coreceptor in Pituitary Gonadotrope Cells in Mice. Endocrinology 2018; 159:4077-4091. [PMID: 30364975 PMCID: PMC6372943 DOI: 10.1210/en.2018-00770] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 10/22/2018] [Indexed: 02/01/2023]
Abstract
Inhibins are gonadal hormones that act on pituitary gonadotrope cells to suppress FSH synthesis and secretion. Inhibin A and B are heterodimers of the inhibin ⍺-subunit disulfide-linked to one of two inhibin β-subunits. Homodimers or heterodimers of the inhibin β-subunits form the activins, which stimulate FSH production. Activins signal through complexes of type I and II receptor serine/threonine kinases to increase transcription of the FSHβ subunit gene. According to in vitro observations, inhibins impair FSH synthesis by competitively binding to activin type II receptors, particularly in the presence of the TGFβ type III receptor (TGFBR3, or betaglycan). The role of TGFBR3 in inhibin action in vivo has not been determined. Here, we ablated Tgfbr3 specifically in murine gonadotropes. Conditional knockout females were supra-fertile, exhibiting enhanced folliculogenesis, numbers of ovulated eggs per cycle, and litter sizes relative to control mice. Despite these phenotypes, FSH levels appeared to be unaltered in knockout mice, and the mechanisms underlying their enhanced fertility remain unexplained. Inhibin B is the predominant form of the hormone in males and in females during most stages of the estrous cycle. Remarkably, inhibin A, but not inhibin B, suppression of FSH synthesis was impaired in cultured pituitaries of knockout mice, which may explain the absence of discernible changes in FSH levels in vivo. Collectively, these data challenge current dogma by demonstrating that TGFBR3 (betaglycan) functions as an inhibin A, but not an inhibin B, coreceptor in gonadotrope cells in vivo. Mechanisms of inhibin B action merit further investigation.
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Affiliation(s)
- Yining Li
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada
| | - Jérôme Fortin
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada
| | - Luisina Ongaro
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada
| | - Xiang Zhou
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada
| | - Ulrich Boehm
- Department of Pharmacology and Toxicology, University of Saarland School of Medicine, Homburg, Germany
| | | | - Daniel J Bernard
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada
| | - Herbert Y Lin
- Program in Membrane Biology/Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
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13
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Bernard DJ, Brûlé E, Smith CL, Joustra SD, Wit JM. From Consternation to Revelation: Discovery of a Role for IGSF1 in Pituitary Control of Thyroid Function. J Endocr Soc 2018; 2:220-231. [PMID: 29594256 PMCID: PMC5841168 DOI: 10.1210/js.2017-00478] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/01/2018] [Indexed: 01/30/2023] Open
Abstract
Immunoglobulin superfamily, member 1 (IGSF1) is a transmembrane glycoprotein highly expressed in the mammalian pituitary gland. Shortly after its discovery in 1998, the protein was proposed to function as a coreceptor for inhibins (and was even temporarily renamed inhibin binding protein). However, subsequent investigations, both in vitro and in vivo, failed to support a role for IGSF1 in inhibin action. Research on IGSF1 nearly ground to a halt until 2011, when next-generation sequencing identified mutations in the X-linked IGSF1 gene in boys and men with congenital central hypothyroidism. IGSF1 was localized to thyrotrope cells, implicating the protein in pituitary control of the thyroid. Investigations in two Igsf1 knockout mouse models converged to show that IGSF1 deficiency leads to reduced expression of the receptor for thyrotropin-releasing hormone (TRH) and impaired TRH stimulation of thyrotropin secretion, providing a candidate mechanism for the central hypothyroidism observed in patients. Nevertheless, the normal functions of IGSF1 in thyrotropes and other cells remain unresolved. Moreover, IGSF1 mutations are also commonly associated with other clinical phenotypes, including prolactin and growth hormone dysregulation, and macroorchidism. How the loss of IGSF1 produces these characteristics is unknown. Although early studies of IGSF1 ran into roadblocks and blind alleys, armed with the results of detailed clinical investigations, powerful mouse models, and new reagents, the field is now poised to discover IGSF1’s function in endocrine tissues, including the pituitary and testes.
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Affiliation(s)
- Daniel J Bernard
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada.,Department of Anatomy and Cell Biology, McGill University, Montréal, Québec H3A 0C7, Canada
| | - Emilie Brûlé
- Department of Anatomy and Cell Biology, McGill University, Montréal, Québec H3A 0C7, Canada
| | - Courtney L Smith
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
| | - Sjoerd D Joustra
- Department of Pediatrics, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands
| | - Jan M Wit
- Department of Pediatrics, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands
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14
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Villarreal MM, Kim SK, Barron L, Kodali R, Baardsnes J, Hinck CS, Krzysiak TC, Henen MA, Pakhomova O, Mendoza V, O'Connor-McCourt MD, Lafer EM, López-Casillas F, Hinck AP. Binding Properties of the Transforming Growth Factor-β Coreceptor Betaglycan: Proposed Mechanism for Potentiation of Receptor Complex Assembly and Signaling. Biochemistry 2016; 55:6880-6896. [PMID: 27951653 PMCID: PMC5551644 DOI: 10.1021/acs.biochem.6b00566] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
![]()
Transforming
growth factor (TGF) β1, β2, and β3
(TGF-β1–TGF-β3, respectively) are small secreted
signaling proteins that each signal through the TGF-β type I
and type II receptors (TβRI and TβRII, respectively).
However, TGF-β2, which is well-known to bind TβRII several
hundred-fold more weakly than TGF-β1 and TGF-β3, has an
additional requirement for betaglycan, a membrane-anchored nonsignaling
receptor. Betaglycan has two domains that bind TGF-β2 at independent
sites, but how it binds TGF-β2 to potentiate TβRII binding
and how the complex with TGF-β, TβRII, and betaglycan
undergoes the transition to the signaling complex with TGF-β,
TβRII, and TβRI are not understood. To investigate the
mechanism, the binding of the TGF-βs to the betaglycan extracellular
domain, as well as its two independent binding domains, either directly
or in combination with the TβRI and TβRII ectodomains,
was studied using surface plasmon resonance, isothermal titration
calorimetry, and size-exclusion chromatography. These studies show
that betaglycan binds TGF-β homodimers with a 1:1 stoichiometry
in a manner that allows one molecule of TβRII to bind. These
studies further show that betaglycan modestly potentiates the binding
of TβRII and must be displaced to allow TβRI to bind.
These findings suggest that betaglycan functions to bind and concentrate
TGF-β2 on the cell surface and thus promote the binding of TβRII
by both membrane-localization effects and allostery. These studies
further suggest that the transition to the signaling complex is mediated
by the recruitment of TβRI, which simultaneously displaces betaglycan
and stabilizes the bound TβRII by direct receptor–receptor
contact.
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Affiliation(s)
| | | | | | - Ravi Kodali
- Department of Structural Biology, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States
| | - Jason Baardsnes
- National Research Council, Human Health Therapeutics Portfolio , Montréal, Quebec, Canada
| | - Cynthia S Hinck
- Department of Structural Biology, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States
| | - Troy C Krzysiak
- Department of Structural Biology, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States
| | - Morkos A Henen
- Department of Structural Biology, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States
| | | | - Valentín Mendoza
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México , Ciudad de México, Mexico
| | | | | | - Fernando López-Casillas
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México , Ciudad de México, Mexico
| | - Andrew P Hinck
- Department of Structural Biology, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States
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15
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Walton KL, Kelly EK, Johnson KE, Robertson DM, Stanton PG, Harrison CA. A Novel, More Efficient Approach to Generate Bioactive Inhibins. Endocrinology 2016; 157:2799-809. [PMID: 27054553 DOI: 10.1210/en.2015-1963] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Gonadal-derived inhibins are essential factors in mammalian reproduction, negatively regulating pituitary production of FSH. Interestingly, declines in inhibin levels across the menopause transition correlate with not only an increase in FSH but also a rapid decrease in bone mass. Therefore, inhibins have been touted as potential therapeutics for osteoporosis in postmenopausal women. However, as heterodimeric proteins of α- and β- (βA or βB)-subunits, inhibins are difficult to produce recombinantly, are poorly processed to their mature bioactive forms, and their expression is always accompanied by production of activins (β-subunit homodimers), the proteins they antagonize. In this study, we developed the methodology to circumvent most of these issues. Initially, the cleavage sites between the pro- and mature domains of the α- and βA-subunits were modified to ensure complete processing. These modifications led to a marked increase (9-fold) in the levels of bioactive inhibin A and a striking decrease (12.5-fold) in mature activin A production. Next, a single point mutation (M418A) was incorporated into the βA-subunit, which reduced residual activin activity approximately 100-fold and, in so doing, increased inhibin bioactivity 8-fold. Finally, we showed that inhibin A noncovalently associated with its prodomain was more potent (∼20-fold) than mature inhibin A in specific in vitro bioassays, indicating an important role of the prodomain in inhibin bioactivity. In conclusion, the production of potent inhibin analogs in the virtual absence of activin activity will greatly facilitate the investigation of the therapeutic potential of these gonadal hormones on bone and other tissues.
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Affiliation(s)
- Kelly L Walton
- Hudson Institute of Medical Research, Clayton, Victoria 3168, Australia
| | - Emily K Kelly
- Hudson Institute of Medical Research, Clayton, Victoria 3168, Australia
| | | | - David M Robertson
- Hudson Institute of Medical Research, Clayton, Victoria 3168, Australia
| | - Peter G Stanton
- Hudson Institute of Medical Research, Clayton, Victoria 3168, Australia
| | - Craig A Harrison
- Hudson Institute of Medical Research, Clayton, Victoria 3168, Australia
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16
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Bernard DJ. Disinhibiting an Inhibitor: Genetic Engineering Leads to Improvements in Recombinant Inhibin A Production. Endocrinology 2016; 157:2583-5. [PMID: 27363870 DOI: 10.1210/en.2016-1345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Daniel J Bernard
- Department of Pharmacology and Therapeutics, Centre for Research in Reproduction and Development, McGill University, Montreal, Canada QC H3G 1Y6
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17
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Namwanje M, Brown CW. Activins and Inhibins: Roles in Development, Physiology, and Disease. Cold Spring Harb Perspect Biol 2016; 8:cshperspect.a021881. [PMID: 27328872 DOI: 10.1101/cshperspect.a021881] [Citation(s) in RCA: 155] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Since their original discovery as regulators of follicle-stimulating hormone (FSH) secretion and erythropoiesis, the TGF-β family members activin and inhibin have been shown to participate in a variety of biological processes, from the earliest stages of embryonic development to highly specialized functions in terminally differentiated cells and tissues. Herein, we present the history, structures, signaling mechanisms, regulation, and biological processes in which activins and inhibins participate, including several recently discovered biological activities and functional antagonists. The potential therapeutic relevance of these advances is also discussed.
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Affiliation(s)
- Maria Namwanje
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
| | - Chester W Brown
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030 Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030 Texas Children's Hospital, Houston, Texas 77030
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18
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Zhu J, Mishra RK, Schiltz GE, Makanji Y, Scheidt KA, Mazar AP, Woodruff TK. Virtual High-Throughput Screening To Identify Novel Activin Antagonists. J Med Chem 2015; 58:5637-48. [PMID: 26098096 DOI: 10.1021/acs.jmedchem.5b00753] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Activin belongs to the TGFβ superfamily, which is associated with several disease conditions, including cancer-related cachexia, preterm labor with delivery, and osteoporosis. Targeting activin and its related signaling pathways holds promise as a therapeutic approach to these diseases. A small-molecule ligand-binding groove was identified in the interface between the two activin βA subunits and was used for a virtual high-throughput in silico screening of the ZINC database to identify hits. Thirty-nine compounds without significant toxicity were tested in two well-established activin assays: FSHβ transcription and HepG2 cell apoptosis. This screening workflow resulted in two lead compounds: NUCC-474 and NUCC-555. These potential activin antagonists were then shown to inhibit activin A-mediated cell proliferation in ex vivo ovary cultures. In vivo testing showed that our most potent compound (NUCC-555) caused a dose-dependent decrease in FSH levels in ovariectomized mice. The Blitz competition binding assay confirmed target binding of NUCC-555 to the activin A:ActRII that disrupts the activin A:ActRII complex's binding with ALK4-ECD-Fc in a dose-dependent manner. The NUCC-555 also specifically binds to activin A compared with other TGFβ superfamily member myostatin (GDF8). These data demonstrate a new in silico-based strategy for identifying small-molecule activin antagonists. Our approach is the first to identify a first-in-class small-molecule antagonist of activin binding to ALK4, which opens a completely new approach to inhibiting the activity of TGFβ receptor superfamily members. in addition, the lead compound can serve as a starting point for lead optimization toward the goal of a compound that may be effective in activin-mediated diseases.
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Affiliation(s)
- Jie Zhu
- †Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, 303 East Superior Street, Lurie 10-250, Chicago, Illinois 60611, United States.,‡Center for Reproductive Science, Northwestern University, Evanston, Illinois 60208, United States
| | - Rama K Mishra
- §Center for Molecular Innovation and Drug Discovery, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Gary E Schiltz
- §Center for Molecular Innovation and Drug Discovery, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Yogeshwar Makanji
- †Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, 303 East Superior Street, Lurie 10-250, Chicago, Illinois 60611, United States
| | - Karl A Scheidt
- §Center for Molecular Innovation and Drug Discovery, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.,⊥Department of Chemistry, Northwestern University, Evanston, 60208, Illinois, United States.,∥Department of Pharmacology, Northwestern University, Chicago, Illinois 60611, United States
| | - Andrew P Mazar
- ∥Department of Pharmacology, Northwestern University, Chicago, Illinois 60611, United States.,□Chemistry of Life Processes Institute, Northwestern University, 2170 Campus Drive, Evanston, Illinois 60208, United States
| | - Teresa K Woodruff
- †Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, 303 East Superior Street, Lurie 10-250, Chicago, Illinois 60611, United States.,‡Center for Reproductive Science, Northwestern University, Evanston, Illinois 60208, United States.,□Chemistry of Life Processes Institute, Northwestern University, 2170 Campus Drive, Evanston, Illinois 60208, United States
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19
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Zhao C, Qiao C, Tang RH, Jiang J, Li J, Martin CB, Bulaklak K, Li J, Wang DW, Xiao X. Overcoming Insulin Insufficiency by Forced Follistatin Expression in β-cells of db/db Mice. Mol Ther 2015; 23:866-874. [PMID: 25676679 PMCID: PMC4427879 DOI: 10.1038/mt.2015.29] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 02/04/2015] [Indexed: 12/19/2022] Open
Abstract
Diabetes poses a substantial burden to society as it can lead to serious complications and premature death. The number of cases continues to increase worldwide. Two major causes of diabetes are insulin resistance and insulin insufficiency. Currently, there are few antidiabetic drugs available that can preserve or protect β-cell function to overcome insulin insufficiency in diabetes. We describe a therapeutic strategy to preserve β-cell function by overexpression of follistatin (FST) using an AAV vector (AAV8-Ins-FST) in diabetic mouse model. Overexpression of FST in the pancreas of db/db mouse increased β-cell islet mass, decreased fasting glucose level, alleviated diabetic symptoms, and essentially doubled lifespan of the treated mice. The observed islet enlargement was attributed to β-cell proliferation as a result of bioneutralization of myostatin and activin by FST. Overall, our study indicates overexpression of FST in the diabetic pancreas preserves β-cell function by promoting β-cell proliferation, opening up a new therapeutic avenue for the treatment of diabetes.
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Affiliation(s)
- Chunxia Zhao
- Division of Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA; Cardiovascular Division of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chunping Qiao
- Division of Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Ru-Hang Tang
- Division of Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Jiangang Jiang
- Cardiovascular Division of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jianbin Li
- Division of Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Carrie Bette Martin
- Division of Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Karen Bulaklak
- Division of Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Juan Li
- Division of Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Dao Wen Wang
- Cardiovascular Division of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiao Xiao
- Division of Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA.
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20
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21
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Makanji Y, Zhu J, Mishra R, Holmquist C, Wong WPS, Schwartz NB, Mayo KE, Woodruff TK. Inhibin at 90: from discovery to clinical application, a historical review. Endocr Rev 2014; 35:747-94. [PMID: 25051334 PMCID: PMC4167436 DOI: 10.1210/er.2014-1003] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
When it was initially discovered in 1923, inhibin was characterized as a hypophysiotropic hormone that acts on pituitary cells to regulate pituitary hormone secretion. Ninety years later, what we know about inhibin stretches far beyond its well-established capacity to inhibit activin signaling and suppress pituitary FSH production. Inhibin is one of the major reproductive hormones involved in the regulation of folliculogenesis and steroidogenesis. Although the physiological role of inhibin as an activin antagonist in other organ systems is not as well defined as it is in the pituitary-gonadal axis, inhibin also modulates biological processes in other organs through paracrine, autocrine, and/or endocrine mechanisms. Inhibin and components of its signaling pathway are expressed in many organs. Diagnostically, inhibin is used for prenatal screening of Down syndrome as part of the quadruple test and as a biochemical marker in the assessment of ovarian reserve. In this review, we provide a comprehensive summary of our current understanding of the biological role of inhibin, its relationship with activin, its signaling mechanisms, and its potential value as a diagnostic marker for reproductive function and pregnancy-associated conditions.
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Affiliation(s)
- Yogeshwar Makanji
- Department of Obstetrics and Gynecology (Y.M., J.Z., C.H., W.P.S.W., T.K.W.), Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60610; Center for Molecular Innovation and Drug Discovery (R.M., C.H.), Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208; and Department of Molecular Biosciences (N.B.S., K.E.M., T.K.W.), Center for Reproductive Science, Northwestern University, Evanston, Illinois 60208
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22
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Walentowicz P, Krintus M, Sadlecki P, Grabiec M, Mankowska-Cyl A, Sokup A, Walentowicz-Sadlecka M. Serum inhibin A and inhibin B levels in epithelial ovarian cancer patients. PLoS One 2014; 9:e90575. [PMID: 24599287 PMCID: PMC3944095 DOI: 10.1371/journal.pone.0090575] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 02/01/2014] [Indexed: 12/11/2022] Open
Abstract
The aim of our study was to examine serum inhibin A and inhibin B concentrations in ovarian cancer patients in relation to clinicopathological features and 5-year survival. Material and Methods We enrolled 90 epithelial ovarian cancer patients in our study, aged 45–81 years, who underwent optimal cytoreductive surgery. In all patients, serum inhibin A and inhibin B concentrations were measured using a two-step sandwich type enzyme immunoassay before surgery. Results In the group of patients with ovarian cancer median serum concentration of inhibin A was 3.87 pg/mL (0.96–10.09) and inhibin B was 13.9 pg/mL (5.1–45.0). Median concentrations of inhibin A and B in relation to FIGO stage and histological subtype did not differ significantly. Inhibin A levels were significantly higher in patients with lower grading (G1 and G2) in comparison to those with higher grade G3 (p = 0.001). There were no differences in inhibin B concentrations in relation to grading. The Kaplan-Meier analyses demonstrated no differences in survival rate in relation to inhibin A levels, while there was a stepwise impairment of 5-years survival with increased inhibin B level. In the group of patients with inhibin B levels higher than 20 pg/ml the survival rate was lower (p = 0,00625, log-rank test). Conclusion 1. Higher inhibin A serum levels were found in patients with highly differentiated ovarian carcinoma compared to the group of patients with a poorly differentiated cancer, which may confirm the influence of inhibin A on cell proliferation processes. 2. A significant importance of inhibin B was demonstrated in the prediction of death within less than a five year period. The probability of survival in patients featuring high inhibin B levels was lower with statistical significance. This may indicate the need for further studies on how to block the inhibin B activation pathway in the ovarian carcinoma therapy.
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Affiliation(s)
- Pawel Walentowicz
- Department of Obstetrics and Gynecology, L.Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Magdalena Krintus
- Department of Laboratory Medicine, L.Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Pawel Sadlecki
- Department of Obstetrics and Gynecology, L.Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Marek Grabiec
- Department of Obstetrics and Gynecology, L.Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Aneta Mankowska-Cyl
- Department of Laboratory Medicine, L.Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Alina Sokup
- Department of Gastroenterology, Angiology and Internal Diseases, Nicolaus Copernicus University, Dr. J. Biziel University Hospital, Bydgoszcz, Poland
| | - Malgorzata Walentowicz-Sadlecka
- Department of Obstetrics and Gynecology, L.Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Bydgoszcz, Poland
- * E-mail:
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23
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Tournier I, Marlin R, Walton K, Charbonnier F, Coutant S, Théry JC, Charbonnier C, Spurrell C, Vezain M, Ippolito L, Bougeard G, Roman H, Tinat J, Sabourin JC, Stoppa-Lyonnet D, Caron O, Bressac-de Paillerets B, Vaur D, King MC, Harrison C, Frebourg T. Germline mutations of inhibins in early-onset ovarian epithelial tumors. Hum Mutat 2013; 35:294-7. [PMID: 24302632 PMCID: PMC4284000 DOI: 10.1002/humu.22489] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 11/22/2013] [Indexed: 01/26/2023]
Abstract
To identify novel genetic bases of early-onset epithelial ovarian tumors, we used the trio exome sequencing strategy in a patient without familial history of cancer who presented metastatic serous ovarian adenocarcinomas at 21 years of age. We identified a single de novo mutation (c.1157A>G/p.Asn386Ser) within the INHBA gene encoding the βA-subunit of inhibins/activins, which play a key role in ovarian development. In vitro, this mutation alters the ratio of secreted activins and inhibins. In a second patient with early-onset serous borderline papillary cystadenoma, we identified an unreported germline mutation (c.179G>T/p.Arg60Leu) of the INHA gene encoding the α-subunit, the partner of the βA-subunit. This mutation also alters the secreted activin/inhibin ratio, by disrupting both inhibin A and inhibin B biosynthesis. In a cohort of 62 cases, we detected an additional unreported germline mutation of the INHBA gene (c.839G>A/p.Gly280Glu). Our results strongly suggest that inhibin mutations contribute to the genetic determinism of epithelial ovarian tumors.
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Affiliation(s)
- Isabelle Tournier
- Inserm U1079, Institute for Research and Innovation in Biomedicine, University of Rouen, Rouen, Cancéropôle Nord-Ouest, France
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24
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Characterization of the mechanism of inhibin α-subunit gene in mouse anterior pituitary cells by RNA interference. PLoS One 2013; 8:e74596. [PMID: 24098340 PMCID: PMC3789712 DOI: 10.1371/journal.pone.0074596] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 08/03/2013] [Indexed: 12/02/2022] Open
Abstract
Inhibin, a member of the transforming growth factor-β [TGF-β] superfamily, is a suppressor of follicle-stimulating hormone [FSH] release through pituitary–gonadal negative feedback loop to regulate follicular development. In this study, Inhibin α-subunit [Inha] gene was knocked down successfully in mice primary anterior pituitary cells at both transcriptional and translational levels by RNAi-Ready pSIREN-RetroQ-ZsGreen Vector mediated recombinant pshRNA vectors. The results indicated that inhibin silencing significantly promoted apoptosis by up-regulating Caspase-3, Bax and Bcl-2 genes without affecting p53 both at transcriptional and translational levels. Furthermore, it markedly impaired the progression of G1 phase of cell cycle and decreased the amount of cells in S phase [as detected by flow cytometry]. Inhibin silencing resulted in significant up-regulation of mRNA and protein expressions of Gondotropin releasing hormone receptors [GnRHR] and down-regulated mRNA levels of β-glycans with parellel change in the amount of its protein expression. Silencing of inhibin-a significantly increased [P<0.05] activin-β concentration without affecting FSH and LH levels in anterior pituitary cells. These findings revealed that up regulation of GnRH receptors by silencing inhibin a-subunit gene might increase the concentration of activin-β in the culture medium. Inhibin a silencing resulted in increased mRNA and protein expressions of inhibinβ which may demonstrate that both inhibin subunits co-participate in the regulation of reproductive events in anterior pituitary cells. This study concludes that inhibin is a broad regulatory marker in anterior pituitary cells by regulating apoptosis, cellular progression and simultaneously by vital fluctuations in the hormonal signaling.
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Bilandzic M, Stenvers KL. Reprint of: Betaglycan: a multifunctional accessory. Mol Cell Endocrinol 2012; 359:13-22. [PMID: 22521265 DOI: 10.1016/j.mce.2012.03.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 04/18/2011] [Accepted: 04/18/2011] [Indexed: 12/21/2022]
Abstract
Betaglycan is a co-receptor for the TGFβ superfamily, particularly important in establishing the potency of its ligands on their target cells. In recent years, new insights have been gained into the structure and function of betaglycan, expanding its role from that of a simple co-receptor to include additional ligand-dependent and ligand-independent roles. This review focuses on recent advances in the betaglycan field, with a particular emphasis on its newly discovered actions in mediating the trafficking of TGFβ superfamily receptors and as a determinant of the functional output of TGFβ superfamily signalling. In addition, this review encompasses a discussion of the emerging roles of the betaglycan/inhibin pathway in reproductive cancers and disease.
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Affiliation(s)
- Maree Bilandzic
- Prince Henry's Institute, PO Box 5152, Clayton, Victoria 3168, Australia.
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26
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Walton KL, Makanji Y, Harrison CA. New insights into the mechanisms of activin action and inhibition. Mol Cell Endocrinol 2012; 359:2-12. [PMID: 21763751 DOI: 10.1016/j.mce.2011.06.030] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 06/27/2011] [Accepted: 06/27/2011] [Indexed: 12/29/2022]
Abstract
Like other members of the transforming growth factor-β (TGF-β) superfamily, activins are synthesised as precursor molecules comprising an N-terminal prodomain and C-terminal mature region. During synthesis, the prodomain interacts non-covalently with mature activin, maintaining the molecule in a conformation competent for dimerisation. Dimeric precursors are cleaved by proprotein convertases and activin is secreted from the cell non-covalently associated with its propeptide. Extracellularly, the propeptide interacts with heparan sulfate proteoglycans to regulate activin localization within tissues. The mature activin dimer exhibits the classic 'open-hand' structure of TGF-β ligands with 'finger-like' domains projecting outward from the cysteine knot core of the molecule. These finger domains form the binding epitopes for type I and II serine/threonine kinase receptors. Activins ability to access its signalling receptors is regulated by the extracellular binding proteins, follistatin, follistatin-like-3, and by inhibins, which, in the presence of betaglycan, sequester type II receptors.
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Affiliation(s)
- Kelly L Walton
- Prince Henry's Institute of Medical Research, 246 Clayton Road, Clayton, Vic 3168, Australia
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Knight PG, Satchell L, Glister C. Intra-ovarian roles of activins and inhibins. Mol Cell Endocrinol 2012; 359:53-65. [PMID: 21664422 DOI: 10.1016/j.mce.2011.04.024] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Revised: 04/26/2011] [Accepted: 04/27/2011] [Indexed: 01/11/2023]
Abstract
Granulosa cells are the main ovarian source of inhibins, activins and activin-binding protein (follistatin) while germ (oogonia, oocytes) and somatic (theca, granulosa, luteal) cells express activin receptors, signaling components and inhibin co-receptor (betaglycan). Activins are implicated in various intra-ovarian roles including germ cell survival and primordial follicle assembly; follicle growth from preantral to mid-antral stages; suppression of thecal androgen production; promotion of granulosa cell proliferation, FSHR and CYP19A1 expression; enhancement of oocyte developmental competence; retardation of follicle luteinization and/or atresia and involvement in luteolysis. Inhibins (primarily inhibin A) are produced in greatest amounts by preovulatory follicles (and corpus luteum in primates) and suppress FSH secretion through endocrine negative feedback. Together with follistatin, inhibins act locally to oppose auto-/paracrine activin (and BMP) signaling thus modulating many of the above processes. The balance between activin-inhibin shifts during follicle development with activin signalling prevailing at earlier stages but declining as inhibin and betaglycan expression rise.
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Affiliation(s)
- Phil G Knight
- School of Biological Sciences, Hopkins Building, University of Reading, Whiteknights, Reading RG6 6UB, UK.
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Zhu J, Lin SJ, Zou C, Makanji Y, Jardetzky TS, Woodruff TK. Inhibin α-subunit N terminus interacts with activin type IB receptor to disrupt activin signaling. J Biol Chem 2012; 287:8060-70. [PMID: 22267736 DOI: 10.1074/jbc.m111.293381] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inhibin is a heterodimeric peptide hormone produced in the ovary that antagonizes activin signaling and FSH synthesis in the pituitary. The inhibin β-subunit interacts with the activin type II receptor (ActRII) to functionally antagonize activin. The inhibin α-subunit mature domain (N terminus) arose relatively early during the evolution of the hormone, and inhibin function is decreased by an antibody directed against the α-subunit N-terminal extension region or by deletion of the N-terminal region. We hypothesized that the α-subunit N-terminal extension region interacts with the activin type I receptor (ALK4) to antagonize activin signaling in the pituitary. Human or chicken free α-subunit inhibited activin signaling in a pituitary gonadotrope-derived cell line (LβT2) in a dose-dependent manner, whereas an N-terminal extension deletion mutant did not. An α-subunit N-terminal peptide, but not a control peptide, was able to inhibit activin A signaling and decrease activin-stimulated FSH synthesis. Biotinylated inhibin A, but not activin A, bound ALK4. Soluble ALK4-ECD bioneutralized human free α-subunit in LβT2 cells, but did not affect activin A function. Competitive binding ELISAs with N-terminal mutants and an N-terminal region peptide confirmed that this region is critical for direct interaction of the α-subunit with ALK4. These data expand our understanding of how endocrine inhibin achieves potent antagonism of local, constitutive activin action in the pituitary, through a combined mechanism of competitive binding of both ActRII and ALK4 by each subunit of the inhibin heterodimer, in conjunction with the co-receptor betaglycan, to block activin receptor-ligand binding, complex assembly, and downstream signaling.
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Affiliation(s)
- Jie Zhu
- Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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Makanji Y, Walton KL, Chan KL, Gregorevic P, Robertson DM, Harrison CA. Generation of a specific activin antagonist by modification of the activin A propeptide. Endocrinology 2011; 152:3758-68. [PMID: 21750050 DOI: 10.1210/en.2011-1052] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Elevated activin A levels in inhibin-deficient mice promote the development of gonadal tumors and induce cachexia by reducing muscle, liver, stomach, and fat mass. Because activin A is an important regulator of tissue growth, inhibiting the actions of this TGFβ family ligand may halt or reverse pathology in diseased tissues. In this study, we modified the activin A propeptide to generate a specific activin antagonist. Propeptides mediate the synthesis and secretion of all TGFβ ligands and, for some family members (e.g. TGFβ1), bind the mature growth factor with high enough affinity to confer latency. By linking the C-terminal region of the TGFβ1 propeptide to the N-terminal region of the activin A propeptide, we generated a chimeric molecule [activin/TGFβ1 propeptide (AT propeptide)] with increased affinity for activin A. The AT propeptide was 30-fold more potent than the activin A propeptide at suppressing activin-induced FSH release by LβT2 pituitary gonadotrope cells. Binding of the AT propeptide to activin A shields the type II receptor binding site, thereby reducing Smad2 phosphorylation and downstream signaling. In comparison with the commonly used activin antagonists, follistatin (IC(50) 0.42 nM), soluble activin type II receptor A-Fc (IC(50) 0.47 nM), and soluble activin type II receptor B-Fc (IC(50) 0.91 nM), the AT propeptide (IC(50) 2.6 nM) was slightly less potent. However, it was more specific, inhibiting activin A and activin B (IC(50) 10.26 nM) but not the closely related ligands, myostatin and growth differentiation factor-11. As such, the AT propeptide represents the first specific activin antagonist, and it should be an effective reagent for blocking activin actions in vivo.
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Affiliation(s)
- Yogeshwar Makanji
- Prince Henry's Institute of Medical Research, 246 Clayton Road, Clayton VIC 3168, Australia
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30
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Bilandzic M, Stenvers KL. Betaglycan: a multifunctional accessory. Mol Cell Endocrinol 2011; 339:180-9. [PMID: 21550381 DOI: 10.1016/j.mce.2011.04.014] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 04/18/2011] [Accepted: 04/18/2011] [Indexed: 10/18/2022]
Abstract
Betaglycan is a co-receptor for the TGFβ superfamily, particularly important in establishing the potency of its ligands on their target cells. In recent years, new insights have been gained into the structure and function of betaglycan, expanding its role from that of a simple co-receptor to include additional ligand-dependent and ligand-independent roles. This review focuses on recent advances in the betaglycan field, with a particular emphasis on its newly discovered actions in mediating the trafficking of TGFβ superfamily receptors and as a determinant of the functional output of TGFβ superfamily signalling. In addition, this review encompasses a discussion of the emerging roles of the betaglycan/inhibin pathway in reproductive cancers and disease.
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Affiliation(s)
- Maree Bilandzic
- Prince Henry's Institute, P.O. Box 5152, Clayton, Victoria 3168, Australia.
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31
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Makanji Y, Harrison CA, Robertson DM. Feedback Regulation by Inhibins A and B of the Pituitary Secretion of Follicle-Stimulating Hormone. VITAMINS AND HORMONES 2011; 85:299-321. [DOI: 10.1016/b978-0-12-385961-7.00014-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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Blair CR, Stone JB, Wells RG. The type III TGF-β receptor betaglycan transmembrane-cytoplasmic domain fragment is stable after ectodomain cleavage and is a substrate of the intramembrane protease γ-secretase. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:332-9. [PMID: 21167215 DOI: 10.1016/j.bbamcr.2010.12.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2010] [Revised: 12/02/2010] [Accepted: 12/07/2010] [Indexed: 11/20/2022]
Abstract
The Type III TGF-β receptor, betaglycan, is a widely expressed proteoglycan co-receptor for TGF-β superfamily ligands. The full-length protein undergoes ectodomain cleavage with release of a soluble ectodomain fragment. The fate of the resulting transmembrane-cytoplasmic fragment, however, has never been explored. We demonstrate here that the transmembrane-cytoplasmic fragment is stable in transfected cells and in cell lines expressing endogenous betaglycan. Production of this fragment is inhibited by the ectodomain shedding inhibitor TAPI-2. Treatment of cells with inhibitors of the intramembrane protease γ-secretase stabilizes this fragment, suggesting that it is a substrate of γ-secretase. Expression of the transmembrane-cytoplasmic fragment as well as γ-secretase inhibitor stabilization are independent of TGF-β1 or -β2 and are unaffected by mutation of the cytoplasmic domain serines that undergo phosphorylation. γ-Secretase inhibition or the expression of a transmembrane-cytoplasmic fragment in HepG2 cells blunted TGF-β2 signaling. Our findings thus suggest that the transmembrane-cytoplasmic fragment remaining after betaglycan ectodomain cleavage is stable and a substrate of γ-secretase, which may have significant implications for the TGF-β signaling response.
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Affiliation(s)
- Cheyne R Blair
- Cellular and Molecular Biology Graduate Group, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
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Glister C, Satchell L, Knight PG. Changes in expression of bone morphogenetic proteins (BMPs), their receptors and inhibin co-receptor betaglycan during bovine antral follicle development: inhibin can antagonize the suppressive effect of BMPs on thecal androgen production. Reproduction 2010; 140:699-712. [DOI: 10.1530/rep-10-0216] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We reported previously that bone morphogenetic proteins (BMPs) potently suppress CYP17 expression and androgen production by bovine theca interna cells (TC)in vitro. In this study, real-time PCR was used to analyse gene expression in TC and granulosa cell (GC) layers from developing bovine antral follicles (1–18 mm). Abundance of mRNA transcripts for four BMPs (BMP2,BMP4,BMP6, andBMP7) and associated type I (BMPR1A,BMPR1B,ACVR1andACVR1B) and type II (BMPR2,ACVR2AandACVR2B) receptors showed relatively modest, though significant, changes during follicle development.BMP2was selectively expressed in GC, whileBMP6,BMP7and betaglycan (TGFBR3) were more abundant in TC. Abundance of betaglycan mRNA (inhibin co-receptor) in TC increased progressively (fivefold;P<0.001) as follicles grew from 1–2 to 9–10 mm. This suggests a shift in thecal responsiveness to GC-derived inhibin, produced in increasing amounts as follicles achieve dominance. This prompted us to investigate whether inhibin can function as a physiological antagonist of BMP action on bovine TCin vitro, in a manner comparable to that for activin signalling. BMP4, BMP6 and BMP7 abolished LH-induced androstenedione secretion and suppressedCYP17mRNA >200-fold (P<0.001), while co-treatment with inhibin-A reversed the suppressive action of BMP in each case (P<0.001). Results support a physiological role for granulosa-derived inhibin as an antagonist of BMP action on thecal androgen synthesis. A shift in intrafollicular balance between thecal BMP signalling (inhibitory for androgen synthesis) and betaglycan-dependent inhibin signalling (stimulatory for androgen synthesis) accords with the physiological requirement to deliver an adequate supply of aromatase substrate to GC of developing follicles.
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Stenvers KL, Findlay JK. Inhibins: from reproductive hormones to tumor suppressors. Trends Endocrinol Metab 2010; 21:174-80. [PMID: 20005735 DOI: 10.1016/j.tem.2009.11.009] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 11/23/2009] [Accepted: 11/23/2009] [Indexed: 11/30/2022]
Abstract
Inhibins are peptide hormones shown originally to be produced by the gonads to regulate the secretion of follicle stimulating hormone by pituitary gonadotropes. Although gonadotropes have been regarded as the canonical inhibin target cells, in recent years extrapituitary actions of inhibins have come into the spotlight. In particular, disruptions to the local actions of inhibins in peripheral tissues might underlie certain diseases, especially cancers of the reproductive tract. This review focuses on recent advances in the inhibin field, with a particular emphasis on the determinants of inhibin availability, mechanisms of inhibin action, and the physiological relevancy of local inhibin actions in the development and progression of reproductive cancers.
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Affiliation(s)
- Kaye L Stenvers
- Prince Henry's Institute of Medical Research, Clayton, Victoria 3168 Australia.
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Abstract
BACKGROUND Elucidation of the causes of premature ovarian failure (POF) is difficult due to the heterogeneity of the condition. Inhibin is a potential candidate gene for POF based on its dual actions on FSH secretion by the pituitary and gametogenesis in the gonads. A missense mutation in the inhibin alpha subunit gene (INHA G769A) is associated with POF in several populations. However, there is phenotypic heterogeneity in INHA G769A mutation carriers. METHODS Relevant studies were identified by searching PubMed and mutational frequencies combined for meta-analysis. RESULTS Meta-analysis of published studies revealed a risk difference of 0.04 (-0.030 to 0.11). The occurrence of asymptomatic carriers in populations suggests incomplete penetrance and/or a multi-genetic cause of POF. We propose that a decline in inhibin bioactivity caused by the mutation could increase FSH levels; and in a susceptible individual, the heightened sensitivity to gonadotrophins causes POF. Impaired paracrine effects of inhibin could impact folliculogenesis due to reduced antagonism of activin, bone morphogenetic protein 15 and growth differentiation factor 9. Functional studies of this mutation indicate normal production of dimeric inhibin A and B and impaired bioactivity of inhibin B. CONCLUSIONS The identification of an autosomal mutation in the inhibin alpha subunit gene that is significantly linked to POF in certain ethnic populations highlights the role of inhibin in the regulation of ovarian biology and fertility. Although the reduction of inhibin B bioactivity by the INHA G769A mutation is clearly not the only cause, evidence suggests that this change may serve as a susceptibility factor, increasing the likelihood of POF.
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Affiliation(s)
- A L Chand
- Prince Henry's Institute of Medical Research, Clayton, VIC 3168, Australia.
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Abstract
A large body of evidence points to the existence of a close, dynamic relationship between the immune system and the male reproductive tract, which has important implications for our understanding of both systems. The testis and the male reproductive tract provide an environment that protects the otherwise highly immunogenic spermatogenic cells and sperm from immunological attack. At the same time, secretions of the testis, including androgens, influence the development and mature functions of the immune system. Activation of the immune system has negative effects on both androgen and sperm production, so that systemic or local infection and inflammation compromise male fertility. The mechanisms underlying these interactions have begun to receive the attention from reproductive biologists and immunologists that they deserve, but many crucial details remain to be uncovered. A complete picture of male reproductive tract function and its response to toxic agents is contingent upon continued exploration of these interactions and the mechanisms involved.
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Key Words
- cytokines
- immunity
- immunoregulation
- inflammation
- leydig cell
- lymphocytes
- macrophages
- nitric oxide
- prostanoids
- seminal plasma
- sertoli cell
- sperm
- spermatogenesis
- steroidogenesis
- toll-like receptors
- 16:0a-lpc, 1-palmitoyl-sn-glycero-3-phosphocholine
- 18:1a-lpc, 1-oleoyl-sn-glycero-3-phosphocholine
- 18:2a-lpc, 1-linoleoyl-sn-glycero-3-phosphocholine
- 20:4a-lpc, 1-arachidonyl-sn-glycero-3-phosphocholine
- aid, acquired immune deviation
- aire, autoimmune regulator
- ap1, activated protein 1
- apc, antigen-presenting cell
- bambi, bmp and activin membrane-bound inhibitor
- bmp, bone morphogenetic protein
- cox, cyclooxygenase
- crry, complement receptor-related protein
- ctl, cytotoxic t lymphocyte
- eao, experimental autoimmune orchitis
- eds, ethane dimethane sulfonate
- enos, endothelial nos
- fadd, fas-associated death domain protein
- fasl, fas ligand
- fsh, follicle-stimulating hormone
- gc, glucocorticoid
- hcg, human chorionic gonadotropin
- hla, human leukocyte antigen
- hmgb1, high mobility group box chromosomal protein 1
- ice, il1 converting enzyme
- ifn, interferon
- ifnar, ifnα receptor
- il, interleukin
- il1r, interleukin 1 receptor
- il1ra, il1 receptor antagonist
- inos, inducible nitric oxide synthase
- irf, interferon regulatory factor
- jak/stat, janus kinase/signal transducers and activators of transcription
- jnk, jun n-terminal kinase
- lh, luteinizing hormone
- lpc, lysoglycerophosphatidylcholine
- lps, lipopolysaccharide
- map, mitogen-activated protein
- mhc, major histocompatibility complex
- mif, macrophage migration inhibitory factor
- myd88, myeloid differentiation primary response protein 88
- nfκb, nuclear factor kappa b
- nk, cell natural killer cell
- nkt cell, natural killer t cell
- nlr, nod-like receptor
- nnos, neuronal nos
- nod, nucleotide binding oligomerization domain
- p450c17, 17α-hydroxylase/c17-c20 lyase
- p450scc, cholesterol side-chain cleavage complex
- paf, platelet-activating factor
- pamp, pathogen-associated molecular pattern
- pc, phosphocholine
- pg, prostaglandin
- pges, pge synthase
- pgi, prostacyclin
- pla2, phospholipase a2
- pmn, polymorphonuclear phagocyte
- pparγ, peroxisome proliferator-activated receptor γ
- rig, retinoic acid-inducible gene
- rlh, rig-like helicase
- ros, reactive oxygen species
- star, steroidogenic acute regulatory
- tcr, t cell receptor
- tgf, transforming growth factor
- th cell, helper t cell
- tir, toll/il1r
- tlr, toll-like receptor
- tnf, tumor necrosis factor
- tnfr, tnf receptor
- tr1, t regulatory 1
- tradd, tnfr-associated death domain protein
- traf, tumor necrosis factor receptor-associated factor
- treg, regulatory t cell
- trif, tir domain-containing adaptor protein inducing interferon β
- tx, thromboxane
- txas, thromboxane a synthase
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Makanji Y, Temple-Smith PD, Walton KL, Harrison CA, Robertson DM. Inhibin B is a more potent suppressor of rat follicle-stimulating hormone release than inhibin a in vitro and in vivo. Endocrinology 2009; 150:4784-93. [PMID: 19589860 DOI: 10.1210/en.2008-1783] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mature 31- and 34-kDa inhibin A and B negatively regulate the release of FSH from the anterior pituitary; however, a direct comparison of these hormones in vivo has not been undertaken. The bioactivities of highly purified preparations of recombinant human 31-kDa inhibin A and B were determined in rat pituitary cells in vitro, and in ovariectomized adult rats in vivo based on suppression of plasma FSH. The 31-kDa inhibin B was 4.2-fold more bioactive than inhibin A in vitro and 1.45 (1.01-2.79)-fold more bioactive in vivo than 31-kDa inhibin A. However, the corresponding relative binding affinities of 31-kDa inhibin B for betaglycan, betaglycan+activin type II receptor (ActRII)-A, and betaglycan+ActRIIB were lower (IC(50) 2200, 400, and 750 pm, respectively) compared with 31-kDa inhibin A (IC(50) 190, 80, and 290 pm, respectively). A 2.7- and 2.5-fold reduction in in vitro bioactivity was observed between the 31- and 34-kDa inhibin A and 31- and 34-kDa inhibin B, respectively, and these decreases in bioactivities were matched by a parallel reduction in binding to betaglycan and betaglycan+ActRIIA/B. It is concluded that the increased in vitro and in vivo bioactivities of 31-kDa inhibin B cannot be explained by a higher affinity to betaglycan or activin type II receptors; thus, additional factors mediate inhibin B's action. In addition, similar reductions in in vitro bioactivity and betaglycan+ActRIIA/B binding between 31- and 34-kDa inhibins A and B are attributed to hindrance by the additional carbohydrate group at Asn(302) in the formation of a functional inhibin+betaglycan+ActRIIA/B complex.
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Affiliation(s)
- Yogeshwar Makanji
- Department of Obstetrics and Gynecology, Prince Henry's Institute of Medical Research, Clayton, Victoria 3168, Australia.
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Wiater E, Lewis KA, Donaldson C, Vaughan J, Bilezikjian L, Vale W. Endogenous betaglycan is essential for high-potency inhibin antagonism in gonadotropes. Mol Endocrinol 2009; 23:1033-42. [PMID: 19372236 DOI: 10.1210/me.2009-0021] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Inhibins are endocrine hormones that regulate gametogenesis and reproduction through a negative feedback loop with FSH. Inhibin action involves antagonism of signaling by activin or other TGFbeta family ligands. In transfection assays, antagonism by inhibin can be potentiated by betaglycan, a coreceptor for selected TGFbeta family ligands. We tested whether betaglycan is an obligate inhibin coreceptor through disruption of betaglycan function by RNA interference-mediated knockdown and immunoneutralization. Betaglycan knockdown and anti-betaglycan IgG each independently prevented inhibin-A binding to betaglycan and reversed functional effects of transfected betaglycan. Neither betaglycan immunoneutralization nor knockdown affected activin responsiveness in cell lines or in rat anterior pituitary cultures. Betaglycan knockdown decreased the potency of inhibin antagonism of activin-induced FSH secretion in primary gonadotropes. Similarly, anti-betaglycan IgG decreased the potency of inhibin antagonism in primary gonadotropes in a dose-dependent manner, with a reduction in the sensitivity to inhibin-A of greater than 1000-fold. These data establish that betaglycan is an endogenous inhibin coreceptor required for high-sensitivity inhibin antagonism of activin signaling in rat anterior pituitary gonadotropes.
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Affiliation(s)
- Ezra Wiater
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
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Walton KL, Makanji Y, Wilce MC, Chan KL, Robertson DM, Harrison CA. A common biosynthetic pathway governs the dimerization and secretion of inhibin and related transforming growth factor beta (TGFbeta) ligands. J Biol Chem 2009; 284:9311-20. [PMID: 19193648 DOI: 10.1074/jbc.m808763200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The assembly and secretion of transforming growth factor beta superfamily ligands is dependent upon non-covalent interactions between their pro- and mature domains. Despite the importance of this interaction, little is known regarding the underlying regulatory mechanisms. In this study, the binding interface between the pro- and mature domains of the inhibin alpha-subunit was characterized using in vitro mutagenesis. Three hydrophobic residues near the N terminus of the prodomain (Leu(30), Phe(37), Leu(41)) were identified that, when mutated to alanine, disrupted heterodimer assembly and secretion. It is postulated that these residues mediate dimerization by interacting non-covalently with hydrophobic residues (Phe(271), Ile(280), Pro(283), Leu(338), and Val(340)) on the outer convex surface of the mature alpha-subunit. Homology modeling indicated that these mature residues are located at the interface between two beta-sheets of the alpha-subunit and that their side chains form a hydrophobic packing core. Mutation of these residues likely disturbs the conformation of this region, thereby disrupting non-covalent interactions with the prodomain. A similar hydrophobic interface was identified spanning the pro- and mature domains of the inhibin beta(A)-subunit. Mutation of key residues, including Ile(62), Leu(66), Phe(329), and Pro(341), across this interface was disruptive for the production of both inhibin A and activin A. In addition, mutation of Ile(62) and Leu(66) in the beta(A)-propeptide reduced its ability to bind, or inhibit the activity of, activin A. Conservation of the identified hydrophobic motifs in the pro- and mature domains of other transforming growth factor beta superfamily ligands suggests that we have identified a common biosynthetic pathway governing dimer assembly.
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Affiliation(s)
- Kelly L Walton
- Prince Henry's Institute of Medical Research, 246 Clayton Road, Clayton, Victoria 3168, Australia
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