title: Role of protein kinase C in arginine vasopressin-stimulated ERK and p70S6 kinase phosphorylation.
abstract: We previously showed in rat renal glomerular mesangial cells, that arginine vasopressin (AVP)-stimulated cell proliferation was mediated by epidermal growth factor receptor (EGF-R) transactivation, and activation (phosphorylation) of ERK1/2 and p70S6 kinase (Ghosh et al. [2001]: Am J Physiol Renal Physiol 280:F972-F979]. In this paper, we extend these observations and show that different protein kinase C (PKC) isoforms play different roles in mediating AVP-stimulated ERK1/2 and p70S6 kinase phosphorylation and cell proliferation. AVP treatment for 0-60 min stimulated the serine/threonine phosphorylation of PKC isoforms alpha, delta, epsilon, and zeta. The activation of PKC was dependent on EGF-R and phosphatidylinositol 3-kinase (PI3K) activation. In addition, inhibition of conventional and novel PKC isoforms by chronic (24 h) exposure to phorbol 12-myristate 13-acetate (PMA) inhibited AVP-induced activation of ERK and p70S6 kinase as well as EGF-R phosphorylation. Rottlerin, a specific inhibitor of PKCdelta, inhibited both ERK and p70S6 kinase phosphorylation and cell proliferation. In contrast, a PKCepsilon translocation inhibitor decreased ERK1/2 activation without affecting p70S6 kinase or cell proliferation, while a dominant negative PKCzeta (K281W) cDNA delayed p70S6 kinase activation without affecting ERK1/2. On the other hand, Gö6976, an inhibitor of conventional PKC isoforms, did not affect p70S6 kinase, but stimulated ERK1/2 phosphorylation without affecting cell proliferation. Our results indicate that PKCdelta plays an important role in AVP-stimulated ERK and p70S6 kinase activation and cell proliferation.
authors.affiliation: Department of Surgery, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229, USA.
authors.forename: Paramita M
authors.initials: PM
authors.lastname: Ghosh
authors.forename: Roble
authors.initials: R
authors.lastname: Bedolla
authors.forename: Charles A
authors.initials: CA
authors.lastname: Thomas
authors.forename: Jeffrey I
authors.initials: JI
authors.lastname: Kreisberg
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005920:Glomerular Mesangium / Q000166:cytology / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D012076:Renal Agents / Q000494:pharmacology*; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D004791:Enzyme Inhibitors; D007527:Isoenzymes; D012076:Renal Agents; D001127:Arginine Vasopressin; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases