Vasopressin stimulates tyrosine phosphorylation by activation of pkc in the rat smooth muscle cell line, a-10

✍ Scribed by CARLOS B Gonzalez; Carlos E Reyes; Carlos D Figueroa; Valeria Barra; Silvia Troncoso

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 332 KB
• Volume: 23
• Category: Article
• ISSN: 1065-6995
• DOI: 10.1006/cbir.1999.0343

✦ Synopsis

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.