Mediators of the mitogenic action of human V1vascular vasopressin receptors

Abstract

Arginine vasopressin (AVP) activation of V1 vascular receptors (V1Rs) stimulates cell growth and proliferation in different tissues via cellular signaling pathways that remain to be identified. To explore the intracellular mediators of the mitogenic action of V1R, Chinese hamster ovary (CHO) cells were stably transfected with the human V1R cDNA clone we isolated previously. We assessed AVP effects on kinase activation (immunoblotting with phosphospecific antibodies), DNA synthesis (tritiated thymidine uptake), cell cycle progression (flow cytometry analysis after nuclear labeling with propidium iodide), and cell proliferation (conversion of the colorimetric reagent MTS) in the presence or absence of various pathway inhibitors. AVP stimulation of V1Rs leads to the phosphorylation of several kinases, an increase in DNA synthesis, a progression through the S and G2–M phases of the cell cycle, and an increase in cell proliferation. The mediators of the mitogenic action of V1R activation included calcium mobilization, coupling to a Gq protein, and the simultaneous and parallel activation of several kinases, mainly calcium/calmodulin-dependent kinase II, phosphatidylinositol 3 kinase, protein kinase C, and p42/p44 mitogen-activated protein kinase.