Molecular Cloning and Characterization of Two Pig Vasoactive Intestinal Polypeptide Receptors (VPAC(1)-R and VPAC(2)-R)

摘要

We here report the cloning, tissue expression, and functional analyses of the two pig vasoactive intestinal polypeptide (VIP) receptors (pVPAC(1)-R and pVPAC(2)-R). The cloned full-length pVPAC(1)-R and pVPAC(2)-R share high structural similarity with their mammalian counterparts. Functional assay revealed that the full-length pVPAC(1)-R and pVPAC(2)-R-expressed Chinese hamster ovary (CHO) cells could be activated by pVIP and pPACAP(38) potently, indicating that pVPAC(1)-R and pVPAC(2)-R are capable of binding VIP and pituitary adenylate cyclase-activating polypeptide (PACAP). In addition to the identification of the transcripts encoding the two full-length receptors, multiple splice transcript variants were isolated. Comparison with the pig genome database revealed that pVPAC(1)-R and pVPAC(2)-R share a unique gene structure with 14 exons different from other vertebrates. Reverse transcription and polymerase chain reaction (RT-PCR) assays further showed that the transcript encoding the full-length pVPAC(2)-R is widely expressed in all adult tissues whereas the splice variants of pVPAC(1)-R are predominantly expressed in all tissues instead of the transcript encoding the full-length receptor, hinting that pVPAC(2)-R may play more important roles than pVPAC(1)-R in mediating VIP and PACAP actions. Our present findings help to elucidate the important role of VIP and PACAP and promote to rethink of their species-specific physiological roles including their actions in regulation of phenotypic traits in pigs.