title: The significance of Ciona intestinalis as a stem organism in integrative studies of functional evolution of the chordate endocrine, neuroendocrine, and nervous systems.
abstract: Ascidians are the closest phylogenetic neighbors to vertebrates and are believed to conserve the evolutionary origin in chordates of the endocrine, neuroendocrine, and nervous systems involving neuropeptides and peptide hormones. Ciona intestinalis harbors various homologs or prototypes of vertebrate neuropeptides and peptide hormones including gonadotropin-releasing hormones (GnRHs), tachykinins (TKs), and calcitonin, as well as Ciona-specific neuropeptides such as Ciona vasopressin, LF, and YFV/L peptides. Moreover, molecular and functional studies on Ciona tachykinin (Ci-TK) have revealed the novel molecular mechanism of inducing oocyte growth via up-regulation of vitellogenesis-associated protease activity, which is expected to be conserved in vertebrates. Furthermore, a series of studies on Ciona GnRH receptor paralogs have verified the species-specific regulation of GnRHergic signaling including unique signaling control via heterodimerization among multiple GnRH receptors. These findings confirm the remarkable significance of ascidians in investigations of the evolutionary processes of the peptidergic systems in chordates, leading to the promising advance in the research on Ciona peptides in the next stage based on the recent development of emerging technologies including genome-editing techniques, peptidomics-based multi-color staining, machine-learning prediction, and next-generation sequencing. These technologies and bioinformatic integration of the resultant "multi-omics" data will provide unprecedented insights into the comprehensive understanding of molecular and functional regulatory mechanisms of the Ciona peptides, and will eventually enable the exploration of both conserved and diversified endocrine, neuroendocrine, and nervous systems in the evolutionary lineage of chordates.
authors.affiliation: Bioorganic Research Institute, Suntory Foundation for Life Sciences, 1-1-1 Wakayamadai, Shimamoto, Mishima, Osaka 618-8503, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Matsubara
authors.affiliation: Bioorganic Research Institute, Suntory Foundation for Life Sciences, 1-1-1 Wakayamadai, Shimamoto, Mishima, Osaka 618-8503, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kawada
authors.affiliation: Bioorganic Research Institute, Suntory Foundation for Life Sciences, 1-1-1 Wakayamadai, Shimamoto, Mishima, Osaka 618-8503, Japan.
authors.forename: Tsubasa
authors.initials: T
authors.lastname: Sakai
authors.affiliation: Department of Biological Sciences, Faculty of Science, Nara Women's University, Kitauoyahigashi-machi, Nara 630-8506, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Aoyama
authors.affiliation: Bioorganic Research Institute, Suntory Foundation for Life Sciences, 1-1-1 Wakayamadai, Shimamoto, Mishima, Osaka 618-8503, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Osugi
authors.affiliation: Bioorganic Research Institute, Suntory Foundation for Life Sciences, 1-1-1 Wakayamadai, Shimamoto, Mishima, Osaka 618-8503, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Shiraishi
authors.affiliation: Bioorganic Research Institute, Suntory Foundation for Life Sciences, 1-1-1 Wakayamadai, Shimamoto, Mishima, Osaka 618-8503, Japan. Electronic address: satake@sunbor.or.jp.
authors.forename: Honoo
authors.initials: H
authors.lastname: Satake
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002938:Ciona intestinalis / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D009866:Oogenesis / Q000502:physiology; D010802:Phylogeny; D015398:Signal Transduction / Q000502:physiology*; D015854:Up-Regulation; D014714:Vertebrates / Q000378:metabolism
chemical_list: D009479:Neuropeptides
keywords: Ciona intestinalis; Conservation; Diversification; Evolution; Neuropeptide; Receptor