A PROTEIN-KINASE-C ISOZYME, NPKC-EPSILON, IS INVOLVED IN THE ACTIVATION OF NF-KAPPA-B BY 12-O-TETRADECANOYLPHORBOL-13-ACETATE (TPA) IN RAT 3Y1 FIBROBLASTS

In order to examine whether PKC is involved in the activation of NF-ka ppa B by TPA, we overexpressed a variety of PKC isozymes in rat 3Y1 fi broblasts and monitored the expression of the co-transfected reporter NF-kappa B gene. In contrast to TPA response element (TRE), where over expression of a variety of PKC isozymes results in enhanced activation by TPA, activation of NF-kappa B by TPA is not enhanced by overexpres sion of PKC isozymes such as cPKC alpha, nPKC delta, or nPKC theta. Ho wever, the overexpression of nPKC epsilon does result in enhancement. A kinase-negative point mutant of nPKC epsilon, where Lys at the ATP b inding site is altered to Arg, does not cause this enhancement of NF-k appa B activation. Further, the kinase-negative nPKC epsilon partially suppresses endogenous NF-kappa B activity. These results suggest that nPKC epsilon is specifically involved in the activation of NF-kappa B when cells are treated with TPA. (C) 1995 Academic Press, Inc.