Role of the human V₁vasopressin receptor COOH terminus in internalization and mitogenic signal transduction

Abstract

We studied the role played by the intracellular COOH-terminal region of the human arginine vasopressin (AVP) V1-vascular receptor (V1R) in ligand binding, trafficking, and mitogenic signal transduction in Chinese hamster ovary cells stably transfected with the human AVP receptor cDNA clones that we had isolated previously. Truncations, mutations, or chimeric alterations of the V1R COOH terminus did not alter ligand binding, but agonist-induced V1R internalization and recycling were reduced in the absence of the proximal region of the V(1)R COOH terminus. Coupling to phospholipase C was altered as a function of the COOH-terminal length. Deletion of the proximal portion of the V1R COOH terminus or its replacement by the V2-renal receptor COOH terminus prevented AVP stimulation of DNA synthesis and progression through the cell cycle. Mutation of a kinase consensus motif in the proximal region of the V1R COOH terminus also abolished the mitogenic response. Thus the V1R cytoplasmic COOH terminus is not involved in ligand specificity but is instrumental in receptor trafficking and facilitates the interaction between the intracellular loops of the receptor, G protein, and phospholipase C. It is absolutely required for transmission of the mitogenic action of AVP, probably via a specific kinase phosphorylation site.

Vasopressin up-regulates the expression of growth-related immediate-early genes via two distinct EGF receptor transactivation pathways

“…We also showed that AVP-up-regulated c-Fos and Egr-1 required the activation of PKC, the release of intracellular calcium and β-arrestin 2. These results are consistent with previous experiments indicating that V 1 receptor mutants lacking PKC phosphorylation sites failed to mediate DNA synthesis and progression through the cell cycle [44]. Most importantly, we showed that AVP-up-regulated c-Fos and Egr-1 by activation of two distinct EGFR transactivation signalling pathways.…”

Vasopressin V1a and V1b Receptors: From Molecules to Physiological Systems

“…The COOH terminus of the V1b receptor contains one GRK and two PKC consensus motifs (FIGURE 2). Finally, the COOH terminus of the OT receptor contains three PKC, but no GRK, consensus motifs (46,498). In studies on human AVP/OT receptors, the COOH termini of V1a and V2 receptors specifically associated with GRK5 and/or PKC-␣ in a receptor subtypespecific manner modulated by agonist stimulation.…”

“…It has been demonstrated in a study using cells engineered to express recombinant receptors that the human V1a receptor, but not the V2 receptor, promotes cellular mitogenic signal transduction and [ 3 H]thymidine uptake (498). When the structural requirements for [ 3 H]thymidine uptake were examined by comparing V1a and V2 receptors, it was determined that the cytoplasmic COOH terminus of the V1a receptor is necessary for the stimulation of DNA uptake by AVP (498). In addition to these diverse functions, AVP is pathophysiologically involved in promoting cell proliferation.…”

Soluble Mimics of the Cytoplasmic Face of the Human V1-Vascular Vasopressin Receptor Bind Arrestin2 and Calmodulin

“…These intracellular receptor segments also contain G protein-coupled receptor kinase phosphorylation sites. Ct is phosphorylated by GRK5 and protein kinase C and plays an important role in receptor trafficking (Berrada et al, 2000;Thibonnier et al, 2001b). I3 of the hV1R also contains a protein kinase C consensus motif [(S/T)X(R/K)].…”

“…The V1-vascular receptor is coupled to G q and produces a mitogenic response, whereas the V2-renal receptor is coupled to G s and produces an antimitogenic response (Thibonnier et al, 1998a). Human V1R (hV1R) is expressed in various cell types, including vascular smooth muscle cells, hepatocytes, blood platelets, adrenal cortex, kidney, reproductive organs, spleen, adipocytes, brain, and testis, as the product of the same gene undergoing identical splicing (Thibonnier et al, 2001b). Abnormal vasopressin levels may be involved in the pathogenesis of several diseases such as congestive heart failure, nephritic syndrome, liver cirrhosis, and arterial hypertension (Rosenthal et al, 1993;Thibonnier et al, 1998aThibonnier et al, ,b, 2003.…”