EVIDENCE THAT INTERLEUKIN-1 AND PHORBOL ESTERS ACTIVATE NF-KAPPA-B BY DIFFERENT PATHWAYS - ROLE OF PROTEIN-KINASE-C

Nuclear factor kappa B (NF-kappa-B) is a ubiquitous transcription factor that affects expression of many genes, including immunoglobulin kappa (kappa), the interleukin-2 receptor alpha-chain, and two genes in HIV-1. NF-kappa-B can be activated by a number of stimuli, including pharmacological stimulation of protein kinase C by phorbol 12-myristate 13-acetate (PMA) and treatment in vitro with either protein kinase C or protein kinase A. This has lead to the proposal that these kinases are key enzymes in the physiological activation of NF-kappa-B as well. We have used a murine B cell line, 70Z/3, and T cell line, EL-4 6.1 C10, to study the activation of NF-kappa-B by two physiological activators, interleukin-1-alpha (IL-1) and lipopolysaccharide (LPS). There are four reasons to propose that these agents activate pathways that do not include protein kinase C as a major component in these cell lines. First, the protein kinase C inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7) strongly inhibited PMA-induced activation of NF-kappa-B in 70Z/3 cells but had no effect on NF-kappa-B activated by IL-1 or LPS. Second, depletion of protein kinase C by prolonged growth of 70Z/3 in PMA abrogated the capacity of the cells to activate NF-kappa-B in response to further PMA treatment. However, these same cells activated NF-kappa-B normally after either IL-1 or LPS treatment. Third, IL-1 effectively activated NF-kappa-B in EL-4 6.1 C10 cells, but PMA did not. Fourth, inteferon-gamma is a potent activator of protein kinase C in 70Z/3 cells, but is completely inactive in the mobilization of NF-kappa-B. These results suggest that the physiological inducers IL-1 and LPS activate NF-kappa-B by pathways independent of protein kinase C in both 70Z/3 and EL-4 6.1 C10 cells.