title: Nonreproductive role of gonadotropin-releasing hormone in the control of ascidian metamorphosis.
abstract: BACKGROUND
  Gonadotropin-releasing hormones (GnRHs) are neuropeptides that play central roles in the reproduction of vertebrates. In the ascidian Ciona intestinalis, GnRHs and their receptors are expressed in the nervous systems at the larval stage, when animals are not yet capable of reproduction, suggesting that the hormones have non-reproductive roles.
  
  
  RESULTS
  We showed that GnRHs in Ciona are involved in the animal's metamorphosis by regulating tail absorption and adult organ growth. Absorption of the larval tail and growth of the adult organs are two major events in the metamorphosis of ascidians. When larvae were treated with GnRHs, they completed tail absorption more frequently than control larvae. cAMP was suggested to be a second messenger for the induction of tail absorption by GnRHs. tGnRH-3 and tGnRH-5 (the "t" indicates "tunicate") inhibited the growth of adult organs by arresting cell cycle progression in parallel with the promotion of tail absorption.
  
  
  CONCLUSIONS
  This study provides new insights into the molecular mechanisms of ascidian metamorphosis conducted by non-reproductive GnRHs.
authors.affiliation: Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan.
authors.forename: Chisato
authors.initials: C
authors.lastname: Kamiya
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Ohta
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Ogura
authors.forename: Keita
authors.initials: K
authors.lastname: Yoshida
authors.forename: Takeo
authors.initials: T
authors.lastname: Horie
authors.forename: Takehiro G
authors.initials: TG
authors.lastname: Kusakabe
authors.forename: Honoo
authors.initials: H
authors.lastname: Satake
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Sasakura
mesh_terms: D000818:Animals; D059447:Cell Cycle Checkpoints / Q000502:physiology; D002938:Ciona intestinalis / Q000196:embryology*; D000242:Cyclic AMP / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D007814:Larva / Q000378:metabolism; D008675:Metamorphosis, Biological / Q000502:physiology*
chemical_list: D007987:Gonadotropin-Releasing Hormone; D000242:Cyclic AMP
keywords: GnRH; ascidian; metamorphosis