Action of starfish gonadotropic hormone: interaction with the receptor and mechanism of gamete shedding

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K06747
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 44040:Morphology and anatomical structure-related
• Research Institution: Showa University
• Principal Investigator: MITA Masatoshi 昭和大学, 医学部, 客員教授 (50190674)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 生殖腺刺激ホルモン / リラキシン様生殖巣刺激ペプチド / G-タンパク質共役受容体 / 生殖制御機構 / ヒトデ

Outline of Final Research Achievements

Orthologs of relaxin-like gonadotrophic peptides (RGPs) were identified or predicted from 24 species of starfish. Some RGPs were chemically synthesized and examined spawning-inducing activities. RGP receptors (RGPRs) were also identified in Patiria pectinifera. The GPCRs were G protein-coupled receptors. Immunohistochemical analysis using anti-RGP antibodies revealed that RGP existed not only in the radial nerve cords and circumoral nerve rings but also in the terminal tentacles and gonoducts. Acetylcholine (ACh) was found within ovaries and testes. Thus presumably, RGP secreted from gonoducts stimulates ovarian follicle cells or interstitial cells, to produce maturation-inducing hormone, 1-methyladenine, resulting oocyte maturation and ACh secretion to shed mature eggs or spermatozoa.

Free Research Field

生物学

Academic Significance and Societal Importance of the Research Achievements

ヒトデのRGPは無脊椎動物で世界で最初に同定された生殖腺刺激ホルモン様活性物質でヒトの妊娠期の女性ホルモンとして知られるリラキシンとよく似た2本鎖ペプチドである。最近、RGPはヒトデ以外の他の棘皮動物（ナマコ類やクモヒトデ類）においても生殖腺刺激ホルモン様活性を持つことが明らかになった。さらにショウジョウバエの生殖巣の発達にリラキシン様ペプチド(Dilp8)とその受容体(Lgr3)が制御していることが示されている。それ故、本研究の成果は、ヒトデの生殖研究分野に新たな研究基盤を確立したばかりでなく、新口動物と旧口動物にまたがるリラキシン様ペプチドとその受容体の分子共進化を知る切っ掛けとなった。