title: Participation of Gs-proteins in the action of relaxin-like gonad-stimulating substance (GSS) for 1-methyladenine production in starfish ovarian follicle cells.
abstract: Gonad-stimulating substance (GSS) in starfish is the only known invertebrate peptide hormone responsible for final gamete maturation, rendering it functionally analogous to gonadotropins in vertebrates. Recently, we purified GSS from radial nerves in the starfish Asterina pectinifera and identified the chemical structure as a heterodimer composed of two different peptides (A- and B-chain) with disulfide cross-linkages. This study examined the hormonal action of GSS on ovarian follicle cells obtained from ovaries in growing (stage IV) and fully grown (stage V) stages, and particularly the mode of signal transduction. The action of GSS on 1-MeAde production by follicle cells in stage V was mediated through the production of cAMP. In contrast, GSS failed to induce 1-MeAde and cAMP production by follicle cells in stage IV. According to competitive experiments using radioiodinated and radioinert GSS, highly specific binding was observed in follicle cells, though their affinities and numbers in stage IV were inferior to those in stage V. Interestingly, Gsα was not detected immunologically in follicle cell membranes of stage IV. Gβ was also faint in stage IV. Although adenylyl cyclase activity in stage V was dose-dependently activated by GSS in the presence of GTP, neither GSS in the presence of GTP nor nonhydrolyzable GTP analogs were effective on the activity in stage IV. These findings strongly suggest that the failure of GSS to produce 1-MeAde is because of a lack of Gs-proteins in follicle cells at stage IV.
authors: Department of Biology, Faculty of Education, Tokyo Gakugei University, Nukuikita-machi 4-1-1, Koganei-shi, Tokyo 184-8501, Japan. bio-mita@u-gakugei.ac.jp
authors: Masatoshi
authors: M
authors: Mita
authors: Kazutoshi
authors: K
authors: Yamamoto
authors: Masaru
authors: M
authors: Nakamura
authors: Yuki
authors: Y
authors: Takeshige
authors: Miho
authors: M
authors: Watanabe
authors: Yoshitaka
authors: Y
authors: Nagahama
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D047288:Asterina / Q000378:metabolism*; D005260:Female; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism*; D006651:Histocytochemistry; D015151:Immunoblotting; D007447:Invertebrate Hormones / Q000378:metabolism*; D008854:Microscopy, Electron; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D006080:Ovarian Follicle / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D015398:Signal Transduction
chemical_list: D007447:Invertebrate Hormones; C008407:1-methyladenine; D019205:GTP-Binding Protein alpha Subunits, Gs; D000262:Adenylyl Cyclases; D000225:Adenine