title: Vasopressin stimulates tyrosine phosphorylation by activation of PKC in the rat smooth muscle cell line, A-10.
abstract: Arginine vasopressin (AVP)-induced tyrosine phosphorylation was studied in a rat smooth muscle cell line, A-10, by western blotting, using a monoclonal antibody against phosphotyrosine. AVP stimulated the phosphorylation of several cellular proteins of molecular mass 60-130 kDa in a time- and dose-dependent manner. Phosphorylation was mediated largely by V(1)receptor subtype since it was inhibited by selective V(1)antagonist and was only partially elicited by the V(2)agonist, desmopressin. Heterotrimeric G-proteins seemed to be involved in the phosphorylation mechanism because fluoraluminates, an activator of heterotrimeric G-proteins (and thus an uncoupler of the receptor-G-protein interaction) inhibited the AVP-induced phosphorylation. The protein kinase C (PKC) inhibitors: staurosporine, H7 and GF109203X are able to block the AVP-stimulated phosphorylation. The last of these has been shown to be one of the most selective inhibitors of PKC. These results indicate that PKC is upstream of the phosphorylation, a motion which is supported by the fact that the AVP-stimulated phosphorylation was downregulated by phorbol esters.
authors.affiliation: Department of Physiology and Department of Histology and Pathology, Faculty of Medicine, Universidad Austral of Chile, Valdivia, Chile.
authors.forename: C B
authors.initials: CB
authors.lastname: Gonzalez
authors.forename: C E
authors.initials: CE
authors.lastname: Reyes
authors.forename: C D
authors.initials: CD
authors.lastname: Figueroa
authors.forename: V
authors.initials: V
authors.lastname: Barra
authors.forename: S
authors.initials: S
authors.lastname: Troncoso
mesh_terms: D000818:Animals; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*; D014443:Tyrosine / Q000378:metabolism; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014667:Vasopressins / Q000494:pharmacology*
chemical_list: D014662:Vasoconstrictor Agents; D014667:Vasopressins; D014443:Tyrosine; D011493:Protein Kinase C