ACTIVATION OF PROTEIN-KINASE-C IS REQUIRED FOR PROTECTION OF CELLS AGAINST APOPTOSIS INDUCED BY SINGLET OXYGEN

We evaluated the role of protein kinase C (PKC) in the regulation of a poptosis triggered by singlet oxygen. Activation of PKC by short-term 12-O-tetradecanoyl phorbol 13-acetate (TPA) treatment inhibited apopto sis, whereas inhibition of PKC with several inhibitors potentiated thi s process. The antiapoptotic effect of TPA was accompanied by phosphor ylation of extracellular signal-regulated kinase 1/2 (ERK1/2). Pretrea tment of cells with MEK inhibitor, PD98059, inhibited TPA-induced phos phorylation of ERK1/2 and the cytoprotective ability of TPA. These res ults suggest that activation of PKC in HL-60 cells confers protection against apoptosis induced by singlet oxygen and that ERK1/2 mediates a ntiapoptotic signaling of PKC. (C) 1998 Federation of European Biochem ical Societies.