Characterization of chicken secretin (SCT) and secretin receptor (SCTR) genes: A novel secretin-like peptide (SCT-LP) and secretin encoded in a single gene

• Published in: Molecular and cellular endocrinology 2012, Vol.348 (1), p.270-280
• Main Authors: Wang, Yajun, Huang, Guian, Li, Juan, Meng, Fengyan, He, Xiaping, Leung, Frederick C.
• Format: Article
• Language: English
• Subjects: adults; Amino Acid Sequence; amino acids; Animals; bicarbonates; brain; Chicken; Chickens; CHO Cells; Cloning, Molecular; complementary DNA; Cricetinae; Cyclic AMP-Dependent Protein Kinases - metabolism; duodenum; evolution; Evolution, Molecular; Exons; Gastrointestinal Hormones - genetics; Gastrointestinal Hormones - metabolism; Gastrointestinal Hormones - pharmacology; gene expression; genes; Genes, Reporter; liver; Luciferases - biosynthesis; Luciferases - genetics; mammals; messenger RNA; Molecular Sequence Data; Pancreas; Receptors, G-Protein-Coupled - genetics; Receptors, G-Protein-Coupled - metabolism; Receptors, Gastrointestinal Hormone - genetics; Receptors, Gastrointestinal Hormone - metabolism; reverse transcriptase polymerase chain reaction; RNA, Messenger - metabolism; SCTR; Secretin; Secretin - genetics; Secretin - metabolism; Secretin - pharmacology; secretin receptors; Secretin-like peptide; secretion; Sequence Alignment; sequence analysis; Sequence Homology, Amino Acid; Signal Transduction; testes; Tissue Distribution; tissues
• ISSN: 0303-7207; 1872-8057
• DOI: 10.1016/j.mce.2011.09.012

► We identified a novel secretin-like peptide (SCT-LP) in chickens. ► Chicken SCT-LP and secretin are encoded by a single gene. ► Both SCT-LP and secretin can activate chicken secretin receptor potently. ► Secretin was predominantly expressed in chicken small intestine. ► Secretin receptor was expressed in several chicken tissues including pancreas. Secretin and the secretin receptor have been reported to play an important role in regulating pancreatic water and bicarbonate secretion in mammals; however, little is known about their expression, structure, and biological functions in non-mammalian vertebrates including birds. In this study, the full-length cDNAs encoding secretin and secretin receptor have first been cloned from duodenum of adult chickens. The putative chicken secretin receptor (cSCTR) is 449 amino acids in length and shares high sequence identity (58–63%) with its mammalian counterparts. Interestingly, chicken secretin cDNA encodes not only the secretin peptide (cSCT), but also a novel secretin-like peptide (cSCT-LP), which shares high amino acid identity with chicken (56%) and mammalian (48–52%) secretin. Using a pGL3-CRE-luciferase reporter system, we further demonstrated that both cSCT (EC 50: 0.31 nM) and cSCT-LP (EC 50: 1.10 nM), but not other structurally-related peptides, could potently activate cSCTR expressed in CHO cells, suggesting that both peptides may function as potential ligands for cSCTR. Using RT-PCR, the expression of secretin and secretin receptor in adult chicken tissues was also examined. Secretin was detected to be predominantly expressed in small intestine, while the mRNA expression of cSCTR was restricted to several tissues including gastrointestinal tract, liver, testis, pancreas and several brain regions. Collectively, results from present study not only established a molecular basis to elucidate the physiological roles of SCT, SCT-LP and SCTR in chickens, but also provide critical insights into structural and functional changes of secretin and its receptor during vertebrate evolution.