Protein kinases C-beta and C-epsilon link the mast cell high-affinity receptor for IgE to the expression of c-fos and c-jun.

In this report we identify the specific isozymes of protein kinase C (PKC) that are involved in c-fos and c-jun mRNA accumulation in the rat basophilic leukemia cell line RBL-2H3. These cells could be largely depleted of the endogenous PKC isozymes by chronic treatment with phorbol 12-myristate 13-acetate followed by permeabilization of the cells with streptolysin O. The reconstitution of these cells with defined concentrations of either PKC-beta or PKC-epsilon up to 10 nM and 20 nM, respectively, induced c-fos and c-jun in a dose-dependent manner. At high concentrations of PKC-beta and -epsilon the induction of c-fos and c-jun was independent of the aggregation of the high-affinity IgE receptors (Fc epsilon type I receptors). In contrast, at limiting concentrations of these two PKC isozymes, 1 nM, the increase in c-fos and c-jun mRNAs was dependent on the aggregation of the Fc epsilon type I receptors. Unlike PKC-beta and -epsilon, PKC-alpha and PKC-delta failed to reconstitute c-fos and c-jun induction at any dose over the range examined. We conclude that PKC-beta and PKC-epsilon serve as a link between the cell surface receptor and gene expression.