MODULATION OF THE DNA-BINDING ACTIVITY OF TRANSCRIPTION FACTORS CREP,NF-KAPPA-B AND HSF BY H2O2 AND TNF-ALPHA - DIFFERENCES BETWEEN IN-VIVO AND IN-VITRO EFFECTS

Human endothelial cells exposed to H2O2 showed reduced CREP DNA bindin g activity, enhanced HSF activation, arid no induction of NF kappa B b inding activity, Interestingly, H2O2 mas able to induce NF kappa B sub unit p65 translocation in the nucleus, In contrast, cells exposed to T NF alpha showed enhanced CREP binding activity, activation of NF kappa B and no induction of HSE-HSF complex, Addition of H2O2, diamide and iodoacetic acid to the binding reaction mixture markedly reduced the D NA binding ability of the three transcription factors, Thus free sulfh ydryls were important in DNA binding activity of CREP, NF kappa B and HSF, and the lack of induction of NF kappa B by H2O2 in intact cells w as likely caused by oxidation on a thiol, and not by a deficiency in t he activation pathway. (C) 1997 Federation of European Biochemical Soc ieties.