INTERLEUKIN-1-BETA-INDUCED EXPRESSION OF PROTEIN-KINASE-C (PKC)-DELTAAND (PKC)-EPSILON IN NIH 3T3 CELLS

NIH 3T3 cells express the alpha, delta, epsilon and zeta isoenzymes of protein kinase C (PKC). Following stimulation of cells (24 h) with th e pro-inflammatory cytokine, interleukin 1 beta (IL-1 beta), we observ ed, by Western blotting, a dose-dependent effect on the levels of PKC- epsilon and delta, but not on alpha or zeta. Moreover, time course ana lysis revealed that the isoenzymes, PKC-delta and epsilon were induced by IL-1 beta after 7 h. Again, no change in PKC-alpha or zeta levels after IL-1 beta treatment were detected. Incubation with selective PKC inhibitor peptides blocked the PKC-alpha, delta, epsilon and antibodi es binding to their respective isoenzyme bands. We also observed that the addition of the tumour-promoting phorbol ester, phorbol 12-myrista te 13-acetate (PMA), downregulated PKC-alpha, delta and epsilon by 7 h in NIH 3T3 cells. PMA did not affect constitutively produced PKC-zeta protein levels even after 24-h treatment. In summary, these results d emonstrate that IL-1 beta induces protein synthesis of the Ca2+-indepe ndent PKC-delta and epsilon isoforms in NIH 3T3 cells. The differences observed here between PKC isoenzymes in response to IL-1 beta suggest that each isoenzyme mag have a unique role in the signal transduction pathways of IL-1 beta and that such selective expression may influenc e the action of agents which require PKC for signal transduction actin g in concert with IL-1. (C) 1997 Academic Press Limited..