Molecular cloning and functional characterization of a vasotocin receptor subtype expressed in the pituitary gland of the domestic chicken (Gallus domesticus): avian homolog of the mammalian V1b-vasopressin receptor.
The neurohypophysial hormone arginine vasotocin (AVT) stimulates adrenocorticotropin hormone (ACTH) secretion from the avian anterior pituitary gland resulting in increased adrenal secretion of corticosterone in response to stress. Here, we report molecular cloning and functional characterization of a gene encoding an AVT receptor subtype, designated the VT2 receptor, that may mediate the stimulatory effect of AVT on ACTH secretion in birds. The open reading frame predicts a 425 amino acid polypeptide that includes seven segments of 19 to 24 hydrophobic amino acids, typical of guanine nucleotide-protein coupled receptors. Phylogenetic analysis revealed that the VT2 receptor shares highest identity with the mammalian V1b-vasopressin receptor subtype. Expressed VT2 receptors in COS7 cells mediate AVT-induced phosphatidylinositol turnover and Ca(2+) mobilization. In the domestic chicken, expression of VT2 receptor gene transcripts is limited to the pituitary gland. Based on similarities in sequence, site of expression and coupled signal transduction pathways, we conclude that the VT2 receptor is the avian homolog of the mammalian V1b-vasopressin receptor, and therefore may play an important role in the avian stress response.
Cornett
Lawrence E
LE
Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA. cornettlawrencee@uams.edu
Kirby
John D
JD
Vizcarra
Jorge A
JA
Ellison
Jeff C
JC
Thrash
Jarrod
J
Mayeux
Philip R
PR
Crew
Mark D
MD
Jones
Stacie M
SM
Ali
Nawab
N
Baeyens
Dennis A
DA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D002645:Chickens / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008969:Molecular Sequence Data; D010716:Phosphatidylinositols / Q000378:metabolism; D010802:Phylogeny; D010902:Pituitary Gland / Q000378:metabolism*; D017483:Receptors, Vasopressin / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015290:Second Messenger Systems; D017385:Sequence Homology
D010716:Phosphatidylinositols; D017483:Receptors, Vasopressin; C034862:vasotocin receptor; D002118:Calcium