MOLECULAR-CLONING AND EXPRESSION OF RAT V1A AND V2 ARGININE-VASOPRESSIN RECEPTORS

Vasopressin, one of the first characterized neuropeptides, has a wide spectrum of biological action, acting on distinct tissues. Indeed, it is involved in water retention, glucose metabolism, blood pressure and its implication in the CNS has also been described. This diversity of effects on mammalian tissues is mediated by distinct G protein-coupled receptors, acting via distinct second messenger pathways. This receptor family has been subtyped by pharmacological studies, as V1a receptor whose action is mediated by intracellular calcium mobilization, and V2 receptor which is linked to adenylyl cyclase. Since so many essential functions were ensured by vasopressin, molecular characterization of its receptors became soon a great challenge. This prompted us to isolate the cDNA of AVP V1a receptor as the first member of this family, by expression cloning. Intracellular calcium mobilization was therefore assayed after rat liver mRNA injection into Xenopus oocytes. A single clone, encoding a functional AVP receptor corresponding to the V1a subtype was finally characterized as a G protein-coupled receptor. Furthermore, we used homology cloning strategy in order to clone the AVP V2 subtype from a rat kidney cDNA library. A putative receptor clone was finally characterized as the rat V2 receptor cDNA by binding and cAMP increase experiments, on transfected cells.