title: Identification of a potential receptor for both peptide histidine isoleucine and peptide histidine valine.
abstract: Peptide histidine isoleucine (PHI), peptide histidine valine (PHV), and vasoactive intestinal polypeptide (VIP) are cosynthesized from the same precursor and share high levels of structural similarities with overlapping biological functions. In this study, the first PHI/PHV receptor was isolated and characterized in goldfish. To study this receptor using homologous peptides, we have also characterized the goldfish prepro-PHI/VIP, and, surprisingly, a shorter transcript lacking the VIP coding region was isolated. A PHI/VIP precursor without the VIP coding sequence has never before been reported. Initial functional expression of the PHI/PHV receptor in Chinese hamster ovary cells revealed that it could be activated by human PHV [50% effective concentration (EC(50)): 43 nM] and to a lesser extent human PHI (EC(50): 133 nM) and helodermin (EC(50): 166 nM) but not fish and mammalian pituitary adenylate cyclase-activating polypeptides and VIPs. Subsequent studies indicated that, similar to the pituitary adenylate cyclase-activating polypeptide receptors (PAC1-R, VPAC1-R, and VPAC2-R), the receptor isolated in this study is able to interact with goldfish PHI and its C-terminally extended form, PHV with EC(50) values 93 and 43 nM, respectively. Northern blot and RT-PCR/Southern blot analyses revealed that the PHI/VIP gene is expressed in the intestine, brain, and gall bladder and the PHI/PHV receptor gene is primarily expressed in the pituitary and to a lesser extend in the intestine and gall bladder, suggesting that PHI/PHV may play a role, notably in the regulation of pituitary function. In conclusion, our results demonstrate for the first time the existence of a PHI/PHV receptor, indicating that the functions of PHI and PHV could be mediated by their own receptor in addition to VIP receptors.
authors.affiliation: Department of Zoology, University of Hong Kong, Hong Kong, People's Republic of China.
authors.forename: Dicky Lai-Yin
authors.initials: DL
authors.lastname: Tse
authors.forename: Ronald Ting-Kai
authors.initials: RT
authors.lastname: Pang
authors.forename: Anderson On-Lam
authors.initials: AO
authors.lastname: Wong
authors.forename: Siu-Ming
authors.initials: SM
authors.lastname: Chan
authors.forename: Hubert
authors.initials: H
authors.lastname: Vaudry
authors.forename: Billy Kwok-Chong
authors.initials: BK
authors.lastname: Chow
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D016466:CHO Cells; D003001:Cloning, Molecular; D017124:Conserved Sequence; D006224:Cricetinae; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D006054:Goldfish / Q000235:genetics*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism*; D010451:Peptide PHI / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018000:Receptors, Peptide / Q000235:genetics* / Q000378:metabolism*; D014018:Tissue Distribution; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism*
chemical_list: D018076:DNA, Complementary; C042452:PHI peptide receptor; D010446:Peptide Fragments; D010451:Peptide PHI; D011498:Protein Precursors; D011956:Receptors, Cell Surface; D018000:Receptors, Peptide; C053900:peptide histidine valine 42; D014660:Vasoactive Intestinal Peptide