Induction and phosphorylation of protein kinase C-alpha and mitogen activated protein kinase by hypoxia and by radiation in Chinese hamster v79 cells

Protein kinase C (PKC) and mitogen-activated protein (MAP) kinase are protein-serine/threonine kinases which are important regulators of diverse cellular processes including metabolism, proliferation and differentiation. This study shows that both hypoxia and X irradiation of serum-deprived Chinese hamster V79 cells cause the induction and phosphorylation of the PKC-alpha isoform. The increased induction and phosphorylation of PKC occur mainly in the nuclear fraction. Unlike the PKC activator TPA, neither hypoxic nor radiation stress causes translocation of PKC-alpha from the cytosol to the membrane. The induction of PKC-alpha by hypoxia is accompanied by an increased expression of MAP kinase but, in contrast, this does not occur when PKC-alpha is induced by radiation. Radiation, like TPA, cause a complete redistribution of MAP kinase from the cytosol to the nucleus. (C) 1996 by Radiation Research Society.