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 binding activity, enhanced HSF activation, and no induction of NF kappa B binding activity, Interestingly, H2O2 mas able to induce NF kappa B subunit p65 translocation in the nucleus, In contrast, cells exposed to TNF 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 DNA binding ability of the three transcription factors, Thus free sulfhydryls 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 was likely caused by oxidation on a thiol, and not by a deficiency in the activation pathway. (C) 1997 Federation of European Biochemical Societies.