REGULATORY MECHANISM IN STARFISH REPRODUCTION BY A RELAXIN-LIKE GONAD-STIMULATING SUBSTANCE (GSS)

Abstract

Event Abstract Back to Event REGULATORY MECHANISM IN STARFISH REPRODUCTION BY A RELAXIN-LIKE GONAD-STIMULATING SUBSTANCE (GSS) Masatsohi Mita1* 1 Tokyo Gakugei University, Department of Biology, Japan Gonad-stimulating substance (GSS) of starfish is the only known invertebrate peptide hormone responsible for final gamete maturation, rendering it functionally analogous to gonadotropins in the vertebrates. GSS stimulates ovary to induce oocyte maturation by producing maturation-inducing hormone, 1-methyladenine (1-MeAde) in the ovarian follicle cells. Recently, we purified GSS of starfish, Asterina pectinifera, from radial nerves and identified the chemical structure as a heterodimer composed of two different peptides (A- and B-chain) with disulfide cross-linkages. According to phylogenetic analyses, starfish GSS belongs to the insulin/IGF/relaxin superfamily and, more precisely, to the subclass of a relaxin-like peptide. In this study, we examined hormonal actions of GSS on follicle cells in starfish reproduction. The chemically synthesized GSS could stimulate follicle cells in the breeding season to produce 1-MeAde through an increase in cyclic AMP (cAMP). In the presence of GSS, 1-MeAde was synthesized from ATP as a substrate via methylation using S-adenosylmethionine. This suggests that a unique methyltransferase stimulated by cAMP dependent protein kinase is involved in 1-MeAde biosynthesis. In contrast, GSS failed to induce 1-MeAde and cAMP production in follicle cells of young ovaries during oogenesis. According to competitive experiments using radioiodinated and radioinert GSS, however, highly specific bindings were observed in the membrane fraction of follicle cells from ovaries in the growing and fully grown states, suggesting that GSS receptors are distributed on both follicle cell membranes. Additionally, Gsα was immunologically detected in these membrane fractions. At final maturation stage, upon secretion from nervous tissues, GSS interacts with its receptor on the follicle cell surface to activate G-proteins and adenylyl cyclase and induces 1-MeAde production. It may be possible that GSS has another hormonal action on follicle cells during oogenesis. Acknowledgements (supported by JSPS grant No. 21570063 to MM and by NIBB Cooperative Research Program No. 10-307 to MM) References M. Mita, M. Yoshikuni, K. Ohno, Y. Shibata, B. Paul-Prasanth, S. Pichayawasin, M. Isobe, Y. Nagahama, A relaxin-like peptide purified from radial nerves induces oocyte maturation and ovulation in the starfish, Asterina pectinifera, Proc. Nat. Acad. Sci. USA 106 (2009) 9507-9512. M. Mita, K. Yamamoto, M. Nakamura, Y. Nagahama, Hormonal action of relaxin-like gonad-stimulating substance (GSS) on starfish ovaries in growing and fully grown states, Gen. Comp. Endocrinol. 172 (2011) 85-89. Keywords: Gonadotropin, gonad-stimulating substance, relaxin-like peptide, signal-transdcution, Starfish Conference: NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology, Ann Arbor, United States, 13 Jul - 16 Jul, 2011. Presentation Type: Oral Presentation Topic: Gonadal development and gamete maturation Citation: Mita M (2011). REGULATORY MECHANISM IN STARFISH REPRODUCTION BY A RELAXIN-LIKE GONAD-STIMULATING SUBSTANCE (GSS). Front. Endocrinol. Conference Abstract: NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology. doi: 10.3389/conf.fendo.2011.04.00033 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 06 Jul 2011; Published Online: 09 Aug 2011. * Correspondence: Prof. Masatsohi Mita, Tokyo Gakugei University, Department of Biology, Tokyo, 184-8501, Japan, bio-mita@u-gakugei.ac.jp Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Masatsohi Mita Google Masatsohi Mita Google Scholar Masatsohi Mita PubMed Masatsohi Mita Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.