Heterogeneity of protein kinase C isoenzyme gene expression in human T cell lines. Protein kinase C-beta is not required for several T cell functions.

Overview

An early consequence of stimulation of T cells via their Ag receptor is the activation of protein kinase C (PKC). It has recently been shown that PKC activity resides in a family of homologous proteins. Inasmuch as T cells are phenotypically and functionally heterogeneous, we examined the possibility that this heterogeneity may be reflected in differential expression of message for PKC isoenzyme genes. RNA from six leukemic T cell lines was probed for PKC-alpha, -beta, and -gamma message before and after activation. These studies revealed significant differences among these lines. None expressed mRNA for PKC-gamma. Whereas all cells possessed message for PKC-alpha, there was consistent variability in the level expressed. The greatest heterogeneity was seen with PKC-beta. Two cell lines, HUT 78 and HPB-ALL, did not hybridize with the beta probe under any conditions tested. We subsequently used these PKC-beta negative cells to study the role of this isoenzyme in mediating some of the effects seen with phorbol esters that directly bind to and activate PKC. Our results indicate that PKC-beta, which is expressed in some T cells, is not necessary for PMA-induced CD3 or CD4 internalization, IL-2 production, or acquisition of the p55 chain of the IL-2 receptor.