RRC ID 19678
Author Sekiguchi T, Ogasawara M, Satake H.
Title Molecular and functional characterization of cionin receptors in the ascidian, Ciona intestinalis: the evolutionary origin of the vertebrate cholecystokinin/gastrin family.
Journal J. Endocrinol.
Abstract Cholecystokinin (CCK) and gastrin are vertebrate brain-gut peptides featured by a sulfated tyrosine residue and a C-terminally amidated tetrapeptide consensus sequence. Cionin, identified in the ascidian, Ciona intestinalis, the closest species to vertebrates, harbors two sulfated tyrosines and the CCK/gastrin consensus tetrapeptide sequence. While a putative cionin receptor, cior, was cloned, the ligand-receptor relationship between cionin and CioR remains unidentified. Here, we identify two cionin receptors, CioR1 and CioR2, which are the aforementioned putative cionin receptor and its novel paralog respectively. Phylogenetic analysis revealed that CioRs are homologous to vertebrate CCK receptors (CCKRs) and diverged from a common ancestor in the Ciona-specific lineage. Cionin activates intracellular calcium mobilization in cultured cells expressing CioR1 or CioR2. Monosulfated and nonsulfated cionin exhibited less potent or no activity, indicating that CioRs possess pharmacological features similar to the vertebrate CCK-specific receptor CCK1R, rather than its subtype CCK2R, given that a sulfated tyrosine in CCK is required for binding to CCK1R, but not to CCK2R. Collectively, the present data reveal that CioRs share a common ancestor with vertebrate CCKRs and indicate that CCK and CCK1R form the ancestral ligand-receptor pair in the vertebrate CCK/gastrin system. Cionin is expressed in the neural complex, digestive organs, oral siphon and atrial siphons, whereas the expression of ciors was detected mainly in these tissues and the ovary. Furthermore, cioninergic neurons innervate both of the siphons. These results suggest that cionin is involved in the regulation of siphonal functions.
Volume 213(1)
Pages 99-106
Published 2012-4
DOI 10.1530/JOE-11-0410
PII JOE-11-0410
PMID 22289502
MeSH Amino Acid Sequence Animals Cholecystokinin / chemistry Cholecystokinin / physiology* Ciona intestinalis / chemistry Ciona intestinalis / physiology* Consensus Sequence Evolution, Molecular* Gastrins / chemistry Gastrins / physiology* Molecular Sequence Data Neuropeptides / chemistry Neuropeptides / physiology* Oligopeptides / chemistry Oligopeptides / physiology Phylogeny Receptors, Cholecystokinin / chemistry Receptors, Cholecystokinin / physiology* Tyrosine / chemistry
IF 4.381
Times Cited 8
C.intestinalis / (O.japonicus) Wild C. int