In neonatal vascular smooth muscle (VSM) cells, activation of protein kinase C can block the mitogenic response to α-thrombin. The molecular mechanism for this growth inhibition was investigated by looking at early transcriptional events in the cell cycle. Both thrombin and phorbol-12-myristate-13-acetate (PMA) induced mRNA for the c-myc oncogene; peak levels of expression were found 4-5 h after exposure to either agent. When thrombin and PMA were added together, c-myc expression was increased synergistically; down-regulation of protein kinase C suppressed induction of c-myc by thrombin. Thus, c-myc expression varied inversely with cell growth under these conditions. Thrombin and PMA also both induced expression of mRNA for the PDGF-A chain over 4-7h. As for c-myc, PMA and thrombin synergistically increased expression of the PDGF A-chain under conditions where PMA inhibits thrombin-induced DNA synthesis. Thus, mitogenesis and early growth-related gene expresion was dissociated during PMA-mediated growth inhibition.
|Original language||English (US)|
|Number of pages||6|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - Dec 16 1991|
ASJC Scopus subject areas
- Molecular Biology