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)

• Published in: Domestic animal endocrinology 2010, Vol.38 (1), p.13-31
• Main Authors: Wang, Y., Li, J., Wang, C. Ying, Kwok, A. Yan, Zhang, X., Leung, F.C.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; amino acid sequences; Animals; Base Sequence; brain; chickens; Chickens - genetics; Chickens - metabolism; CHO Cells; Cloning, Molecular; complementary DNA; Cricetinae; Cricetulus; G protein-coupled receptors; gene expression; GHRH; GHRH-LPR; GHRH-related peptide; GHRHR; hormone receptors; luciferase; messenger RNA; molecular cloning; Molecular Sequence Data; nucleotide sequences; peptide receptors; peptides; PHI-R; Pituitary Adenylate Cyclase-Activating Polypeptide - genetics; Pituitary Adenylate Cyclase-Activating Polypeptide - metabolism; pituitary gland; Receptors, Neuropeptide - genetics; Receptors, Neuropeptide - metabolism; Receptors, Pituitary Hormone-Regulating Hormone - genetics; Receptors, Pituitary Hormone-Regulating Hormone - metabolism; Receptors, Vasoactive Intestinal Peptide, Type II - genetics; Receptors, Vasoactive Intestinal Peptide, Type II - metabolism; Receptors, Vasoactive Intestinal Polypeptide, Type I - genetics; Receptors, Vasoactive Intestinal Polypeptide, Type I - metabolism; reporter genes; Reverse Transcriptase Polymerase Chain Reaction - veterinary; RNA - chemistry; RNA - genetics; Sequence Alignment; Sequence Analysis, DNA; somatoliberin; tissue distribution; Transfection - veterinary
• ISSN: 0739-7240; 1879-0054
• DOI: 10.1016/j.domaniend.2009.07.008

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.