title: Characterization of the receptors for chicken GHRH and GHRH-related peptides: identification of a novel receptor for GHRH and the receptor for GHRH-LP (PRP).
abstract: Growth hormone-releasing hormone and its structurally related peptides, GHRH-like peptide (GHRH-LP) (also called PRP), peptide histidine-isoleucine (PHI), vasoactive intestinal polypeptide (VIP), and pituitary adenylate cyclase-activating polypeptide (PACAP), have been reported to play important physiological roles in pituitary and extrapituitary tissues of vertebrates; however, little is known about the identity of these GHRH-related peptide receptors in birds. In this study, 6 receptors for GHRH and GHRH-related peptides (cGHRHR(1), cGHRHR(2), cGHRH-LPR, cPAC(1), cVPAC(1), and cVPAC(2)) were cloned from chicken brain or pituitary, and their functionalities were examined in Chinese hamster ovary (CHO) cells using a pGL3-CRE-luciferase reporter system. Results showed that: (1) all receptors are G protein-coupled receptors functionally coupled to the intracellular PKA signaling pathway; (2) 2 GHRH receptors (cGHRHR(1) and cGHRHR(2)) were identified, and both receptors could be potently activated by cGHRH; (3) cGHRH-LP could activate its specific receptor cGHRH-LPR (cPRP-R), and it also activated cGHRHR(1) and cGHRHR(2); and (4) PACAP could potently activate its receptors cPAC(1), cVPAC(1) and cVPAC(2); however, cVPAC(1) and cVPAC(2) could also be effectively activated by cVIP and tPHI, indicating that they can serve as VIP receptors and potential PHI receptors. Using a reverse transcription polymerase chain reaction assay, we further examined the mRNA expression of these receptors in adult chicken tissues. The expressions of cGHRHR(1), cGHRHR(2), and cGHRH-LPR are restricted mainly to the pituitary and/or brain, whereas cPAC(1), cVPAC(1), and cVPAC(2) are expressed in most of the tissues examined. Collectively, our study identified the receptors for chicken GHRH and GHRH-related peptides, including a novel GHRH receptor (cGHRHR(2)), and established a basis to elucidate the roles of these peptides in target tissues.
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Hong Kong, PR China.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: C Ying
authors.initials: CY
authors.lastname: Wang
authors.forename: A Yan
authors.initials: AY
authors.lastname: Kwok
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: F C
authors.initials: FC
authors.lastname: Leung
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002645:Chickens / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D006224:Cricetinae; D003412:Cricetulus; D008969:Molecular Sequence Data; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000737:chemistry / Q000235:genetics; D018013:Receptors, Neuropeptide / Q000235:genetics / Q000378:metabolism*; D018017:Receptors, Pituitary Hormone-Regulating Hormone / Q000235:genetics / Q000378:metabolism*; D051239:Receptors, Vasoactive Intestinal Peptide, Type II / Q000235:genetics / Q000378:metabolism*; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014162:Transfection / Q000662:veterinary
chemical_list: D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D018013:Receptors, Neuropeptide; D018017:Receptors, Pituitary Hormone-Regulating Hormone; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I; D012313:RNA; C048250:somatotropin releasing hormone receptor