title: Involvement of Gαs-proteins in the action of relaxin-like gonad-stimulating substance on 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. In breeding season (stage V), GSS stimulates oocyte maturation to induce 1-methyladenine (1-MeAde) by ovarian follicle cells. The hormonal action of GSS is mediated through the activation of its receptor, G-proteins and adenylyl cyclase. It has been reported that GSS fails to induce 1-MeAde and cyclic AMP (cAMP) production in follicle cells of ovaries during oogenesis (stage IV). This study examined the regulatory mechanism how ovarian follicle cells acquire the potential to respond to GSS by producing 1-MeAde and cAMP. Because the failure of GSS action was due to G-proteins of follicle cells, the molecular structures of Gαs, Gαi, Gαq and Gβ were identified in follicle cells of starfish Asterina pectinifera. The cDNA sequences of Gαs, Gαi, Gαq and Gβ consisted of ORFs encoding 379, 354, 353 and 353 amino acids. The expression levels of Gαs were extremely low in follicle cells at stage IV, whereas the mRNA levels increased markedly in stage V. On contrary, the mRNA levels of Gαi were almost constant regardless of stage IV and V. These findings strongly suggest that de novo synthesis of Gαs-proteins is contributed to the action of GSS on follicle cells to produce 1-MeAde and cAMP.
authors.affiliation: Department of Biology, Faculty of Education, Tokyo Gakugei University, Nukuikita-machi 4-1-1, Koganei-shi, Tokyo 184-8501, Japan. Electronic address: bio-mita@u-gakugei.ac.jp.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Mita
authors.affiliation: Department of Biology, Faculty of Education, Tokyo Gakugei University, Nukuikita-machi 4-1-1, Koganei-shi, Tokyo 184-8501, Japan; Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Wakamatsucho 2-2, Shinjuku-ku, Tokyo 162-8480, Japan.
authors.forename: Shogo
authors.initials: S
authors.lastname: Haraguchi
authors.affiliation: Department of Biology, Faculty of Education, Tokyo Gakugei University, Nukuikita-machi 4-1-1, Koganei-shi, Tokyo 184-8501, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: Department of Biology, Faculty of Education, Tokyo Gakugei University, Nukuikita-machi 4-1-1, Koganei-shi, Tokyo 184-8501, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Takeshige
authors.affiliation: Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Wakamatsucho 2-2, Shinjuku-ku, Tokyo 162-8480, Japan.
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Yamamoto
authors.affiliation: Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Wakamatsucho 2-2, Shinjuku-ku, Tokyo 162-8480, Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Tsutsui
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000096:biosynthesis; D000595:Amino Acid Sequence; D000818:Animals; D047288:Asterina / Q000187:drug effects / Q000378:metabolism*; D001665:Binding Sites; D015153:Blotting, Western; D005260:Female; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007447:Invertebrate Hormones / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000494:pharmacology*; D009865:Oocytes / Q000166:cytology / Q000187:drug effects; D006080:Ovarian Follicle / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012065:Relaxin / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: C425158:GSS protein, Asteroidea; D007447:Invertebrate Hormones; D009479:Neuropeptides; D012333:RNA, Messenger; C008407:1-methyladenine; D012065:Relaxin; D019205:GTP-Binding Protein alpha Subunits, Gs; D000225:Adenine
keywords: G-proteins; Gonad-stimulating substance (GSS); Ovarian follicle cells; Starfish; mRNA expression