ACTIVATION AND ATTENUATION OF TRANSCRIPTION FACTOR NF-KB IN MOUSE GLOMERULAR MESANGIAL CELLS IN RESPONSE TO TUMOR-NECROSIS-FACTOR-ALPHA, IMMUNOGLOBULIN-G, AND ADENOSINE 3' 5'-CYCLIC MONOPHOSPHATE - EVIDENCE FOR INVOLVEMENT OF REACTIVE OXYGEN SPECIES/

The transcription factor NF-kB may play an important role in the respo nse to tissue injury and activation of cytokines. We therefore examine d the regulation of NF-kB in mesangial cells. Treatment of mesangial c ells with TNF-alpha increased nuclear proteins that bound to an NF-kB- specific DNA oligonucleotide. IgG aggregates also increased nuclear NF -kB, demonstrating Fc-tau rreceptor-mediated activation of NF-kB. Trea tment of a cytosolic preparation with the detergent deoxycholate also activated NF-kB. The binding characteristics were typical for NF-kB tr anscription factors as determined by competition experiments with NF-k B-binding wild type kB DNA oligonucleotides or mutated oligonucleotide s. Furthermore, a monoclonal antibody against the p65 subunit of NF-kB prevented the binding of NF-kB to the kB oligonucleotide. To evaluate the potential role of reactive oxygen intermediates in the activation of NF-kB, we used PDTC as a scavenger and HMAP as an inhibitor of NAD PH-dependent oxidase. Both PDTC and HMAP attenuated the increase in nu clear NF-kB in response to either TNF-alpha or IgG complexes. Finally, generation of superoxide anion by xanthine oxidase activated NF-kB, a n effect also mitigated by PDTC. In contrast, exogenous H2O2 did not a ctivate NF-kB. Preincubation of cells with 8 br-cAMP, forskolin, or PG E(2) attenuated the increase in nuclear NF-kB in response to TNF-alpha , aggregated IgG, or superoxide anion. Our results provide support for a role of reactive oxygen intermediates as mediators for activation o f NF-kB in MC after stimulation with TNP-alpha or IgG aggregates. As a n unexpected novel finding we report that cAMP can inhibit activation of NF-kB in MC. These observations may help to explain effects of TNF- alpha, IgG aggregates and cAMP on generation of cytokines by mesangial cells and the resulting glomerular pathophysiology.