title: The role of protein kinase C in activation and termination of mitogen-activated protein kinase activity in angiotensin II-stimulated rat aortic smooth-muscle cells.
abstract: Mitogen-activated protein (MAP) kinases are a family of serine/threonine kinases activated by both tyrosine kinase and G-protein-linked receptor agonists. In rat aorta vascular smooth-muscle cells (VSMC), vasoconstrictors, angiotension II (AII), and alpha-thrombin (alpha-thr), as well as platelet-derived growth factor beta beta (PDGF) stimulated the tyrosine phosphorylation and activation of MAP kinase in a time- and concentration-dependent manner. Pre-treatment of cells with the protein kinase C (PKC) inhibitor Ro-318220, inhibited the initial increase in tyrosine phosphorylation of MAP kinase in response to vasoconstrictors, suggesting the involvement of PKC. Four isoforms of PKC were identified in VSMC by western blotting: alpha, beta, epsilon, and zeta. Downregulation of PKC alpha and PKC epsilon isoforms following chronic phorbol myristate 12, 13-acetate (PMA) pre-treatment resulted in the abolition of AII-stimulated MAP kinase activation. Selective downregulation of PKC alpha following pre-treatment with bryostatin 1 did not affect AII-stimulated MAP kinase. Preincubation of cells with Ro-318220 enhanced the activation of MAP kinase at later time points. In addition, Ro-318220 pre-treatment inhibited the induction by AII of a novel transcriptionally regulated phosphatase, MAP kinase phosphatase-1 (MKP-1). However, AII-mediated activation of MAP kinase was not prolonged by cycloheximide pre-treatment and was not maintained indefinitely by Ro-318220. These results demonstrate a specific role for the Ca(2+)-independent PKC isoform, PKC epsilon, in the activation of MAP kinase in response to vasoconstrictors, and suggest that PKC-mediated induction of MKP-1 plays no role in the termination of transiently activated MAP kinase.
authors.affiliation: Department of Physiology & Pharmacology, University of Strathclyde, Glasgow.
authors.forename: K
authors.initials: K
authors.lastname: Malarkey
authors.forename: A
authors.initials: A
authors.lastname: McLees
authors.forename: A
authors.initials: A
authors.lastname: Paul
authors.forename: G W
authors.initials: GW
authors.lastname: Gould
authors.forename: R
authors.initials: R
authors.lastname: Plevin
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001011:Aorta / Q000166:cytology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000187:drug effects / Q000378:metabolism; D018797:Cell Cycle Proteins; D002478:Cells, Cultured / Q000166:cytology / Q000201:enzymology; D005576:Colforsin / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D054638:Dual Specificity Phosphatase 1; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017874:Immediate-Early Proteins / Q000096:biosynthesis / Q000378:metabolism; D015151:Immunoblotting; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000502:physiology; D008934:Mitogens / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000201:enzymology*; D010749:Phosphoprotein Phosphatases; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D054645:Protein Phosphatase 1; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology; D014443:Tyrosine / Q000378:metabolism; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D017874:Immediate-Early Proteins; D007211:Indoles; D007527:Isoenzymes; D008934:Mitogens; D011500:Protein Synthesis Inhibitors; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D005576:Colforsin; D014443:Tyrosine; D003513:Cycloheximide; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054638:Dual Specificity Phosphatase 1; C517021:Dusp1 protein, rat; D017027:Protein Tyrosine Phosphatases; C064758:Ro 31-8220