title: Structure, expression, and cluster organization of genes encoding gonadotropin-releasing hormone receptors found in the neural complex of the ascidian Ciona intestinalis.
abstract: Gonadotropin-releasing hormone (GnRH) controls reproductive functions in vertebrates. In the present study, two distinct homologues (Ci-GnRHR1 and Ci-GnRHR2) of the vertebrate GnRH receptor (GnRHR) were identified by cDNA cloning from the neural complex of the ascidian Ciona intestinalis. The Ci-GnRHR1 and Ci-GnRHR2 genes are closely linked to each other and form a cluster with another GnRHR-like gene in the genome. Ci-GnRHR1 and Ci-GnRHR2 are more closely related to vertebrate GnRHRs than to the GnRHR-related protein of Drosophila. The phylogenetic analysis indicates that vertebrates and urochordates independently acquired multiple GnRHRs by gene duplications that occurred during the evolution of each lineage. A voltage clamp of Xenopus oocytes injected with synthetic Ci-GnRHR1 mRNA revealed inward currents in response to an ascidian form of GnRH, suggesting that Ci-GnRHR1 is a bona-fide GnRHR. Expression patterns of Ci-GnRHR1 and Ci-GnRHR2 suggest that a GnRH signaling system is involved in regulation of neuronal and reproductive processes as well as in other physiological functions in ascidians.
authors.affiliation: Graduate School of Science, Himeji Institute of Technology, Harima Science Garden City, 3-2-1 Kouto, Kamigori, Ako-gun, 678-1297 Hyogo, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Kusakabe
authors.forename: Sachiko
authors.initials: S
authors.lastname: Mishima
authors.forename: Issei
authors.initials: I
authors.lastname: Shimada
authors.forename: Yuka
authors.initials: Y
authors.lastname: Kitajima
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Tsuda
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002938:Ciona intestinalis / Q000235:genetics* / Q000254:growth & development; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D005260:Female; D018507:Gene Expression Regulation, Developmental; D023061:Gene Order; D005796:Genes / Q000235:genetics; D016678:Genome; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D009415:Nerve Net / Q000254:growth & development / Q000378:metabolism*; D009865:Oocytes / Q000502:physiology; D010802:Phylogeny; D020033:Protein Isoforms / Q000235:genetics / Q000502:physiology; D011966:Receptors, LHRH / Q000235:genetics* / Q000502:physiology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014981:Xenopus
chemical_list: D018076:DNA, Complementary; D020033:Protein Isoforms; D011966:Receptors, LHRH