Protein Kinase C- alpha/betaII, delta, and zeta/lambda involvement in ethanol-induced MAPK expression in vascular...

Protein Kinase C (PKC) exists as one of twelve serine/threonine isoforms and has been found to mediate ethanol-induced activation of the Mitogen-Activated Protein Kinase (MAPK) pathway. The aim of this study was to determine the PKC isoform(s) that are mediators of ethanol-induced MAPK activity (ERK 1 and 2) and to verify the necessity of calcium in this activation process using cell culture in the presence and absence of ethanol, and other agents that modulate PKC expression. Western blotting analysis was used to assess the effect of ethanol on activating classical (alpha/ssII), novel (delta) and atypical (zeta/lambda) PKC isoforms in vascular smooth muscle cells (VSMCs). The results indicate that ethanol treated VSMCs express the classical PKC-alpha/ssII, novel PKC-delta, and atypical PKC-zeta/lambda isoforms. The expression of PKC-alpha/ssII was inhibited within the first two min of stimulation, followed by activation with maximum expression at 10 min. Similarly, PKC-delta and zeta expressions were suppressed during the first two min of ethanol stimulation with maximum increase in expressions at 10 min. The PKC inhibitor GF109203X and the calcium chelating agent BAPTA, enhanced ethanol-induced PKC expression, whereas, diltiazem reduced expression of PKC by 10% of control. On the other hand, BAPTA in the presence of GF10203X inhibited expression of ERK 1 & 2 downstream from the PKC pathway, whereas, BAPTA alone enhanced expression. These results demonstrate also that classical, novel, and atypical PKCs respond to ethanol during the initial phase of activation of ERK 1 & 2.