PKC-delta-dependent pathways contribute to PDGF-stimulated ERK1/2 activation in vascular smooth muscle.
Platelet-derived growth factor (PDGF) is an important regulator of vascular smooth muscle (VSM) cell growth and migration and has been identified as a key mediator of neointima formation resulting from vascular injury. PDGF exerts its effects, in part, through activation of ERK1/2. Previously, we reported that PKC-delta, specifically compared with PKC-alpha, mediated phorbol ester- and ATP-dependent activation of ERK1/2 in VSM cells. The purpose of this study was to determine whether PKC-delta was involved in PDGF-dependent activation of ERK1/2 in VSM cells. The addition of PDGF resulted in the activation, and Src family kinase-dependent tyrosine phosphorylation, of PKC-delta. Treatment with rottlerin (0.1-10 microM), a selective PKC-delta inhibitor, or adenoviral overexpression of kinase-negative PKC-delta significantly attenuated PDGF-induced activation of ERK1/2. The effects of the PKC-delta inhibitors decreased with increasing concentrations of activator PDGF. Interestingly, treatment with Go6976 (0.1-3 microM), a selective inhibitor of cPKCs, or adenoviral overexpression of kinase-negative PKC-alpha also inhibited PDGF-stimulated ERK1/2. Furthermore, inhibition of cPKC activity with Go6976 or overexpression of kinase-negative PKC-alpha attenuated PKC-delta activation and tyrosine phosphorylation in response to PDGF. These studies indicate involvement of both PKC-delta and PKC-alpha isozymes in PDGF-stimulated signaling in VSM and suggest an unexpected role for PKC-alpha in the regulation of PKC-delta activity.
Ginnan
Roman
R
Center for Cardiovascular Sciences, Albany Medical College (MC8) 47 New Scotland Ave., Albany, NY 12208, USA. ginnanr@mail.amc.edu
Singer
Harold A
HA
D000818:Animals; D002478:Cells, Cultured; D004789:Enzyme Activation; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000201:enzymology / Q000502:physiology*; D010982:Platelet-Derived Growth Factor / Q000502:physiology*; D011493:Protein Kinase C / Q000502:physiology*; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000502:physiology
D010982:Platelet-Derived Growth Factor; C497260:Prkcd protein, rat; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D010738:Type C Phospholipases