Protein kinase C gamma expression mimics phorbol ester-induced transcriptional activation of a murine VL30 enhancer element

Protein kinase C (PKC), a critical component in the regulation of cell growth, is thought to participate in transmitting the signals of certain cell surface receptor activation events to the nucleus. We have previously shown that stable expression of the PKC gamma isoenzyme in NIH 3T3 cells causes altered growth and enhanced tumorigenicity. In this report, we show that transient expression of the PKC gamma isoenzyme can trans-activate a murine VL30 enhancer element in a pattern similar to that of the phorbol ester tumor promoter 12-O-tetradecanoylphorbol-13-acetate. In contrast, ras activation of this element is distinct both quantitatively and qualitatively from PKC gamma and 12-O-tetradecanoylphorbol-13-acetate activation. These results provide direct evidence that PKC is the cellular mediator in the activation of phorbol ester-responsive genes and suggest a mechanism by which abnormal PKC expression might lead to altered growth control by changing the pattern of cellular gene expression.