Role of protein kinase C in basal and hydrogen peroxide-stimulated NF-κB activation in the murine macrophage J774A.1 cell line

In macrophages, hydrogen peroxide appears to be a physiological activator of the transcription factor, nuclear factor kappa B (NF-kappa B); however, the molecular basis of H2O2-stimulated NF-kappa B activation is not well defined. The observations that NF-kappa B can be activated in cells by phorbol 12-myristate 13-acetate and in vitro by addition of protein kinase C (PKC) are suggestive of a role of PKC in NF-kappa B activation, which was investigated in the J774A.1 murine macrophage cell line, Basal NF-kappa B DNA-binding activity and nuclear localization were decreased by PKC inhibitors. Although PKC activity was modified by H2O2 with a similar time course as H2O2 activation of NF-kappa B, the H2O2-stimulated increase in NF-kappa B DNA binding and translocation to the nucleus was unaffected by PKC inhibitors, Furthermore, PKC down-regulation (through preincubation with phorbol esters) also affected only baseline NF-kappa B DNA binding but not H2O2-stimulated NF-kappa B activation, Buffering of changes in intracellular free calcium concentration also had no effect upon H2O2-stimulated NF-kappa B activation, Thus, classical PKC activity may modulate basal NF-kappa B activity but does not participate in H2O2-stimulated NF-kappa B activation. (C) 1998 Academic Press.