Modulation of the DNA binding activity of transcription factors CREP, NFκB and HSF by H₂O₂ and TNFα. Differences between in vivo and in vitro effects

Abstract

Human endothelial cells exposed to H 2 0 2 showed reduced CREP DNA binding activity, enhanced HSF activation, and no induction of NFKB binding activity. Interestingly, H 2 0 2 was able to induce NFKB subunit p65 translocation in the nucleus. In contrast, cells exposed to TNFa showed enhanced CREP binding activity, activation of NFKB and no induction of HSE-HSF complex. Addition of H 2 0 2 , 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, NFKB and HSF, and the lack of induction of NFKB by H 2 0 2 in intact cells was likely caused by oxidation on a thiol, and not by a deficiency in the activation pathway.

A Quantitative Study of NF-κB Activation by H2O2: Relevance in Inflammation and Synergy with TNF-α

“…Therefore we think that H 2 O 2 role in TNF-␣-induced NF-B activation switches from stimulatory to inhibitory due to an increase in the oxidative load and not due to an adaptative response of the cells. This is consistent with the dual regulation of NF-B by the redox state of the cell (23)(24)(25).…”

“…NF-B activation has a dual and opposite dependence on oxidative events, because its translocation is favored by oxidative events in the cytosol while binding to DNA requires a reductive environment in the nucleus (23)(24)(25). So, higher levels of oxidative exposure can turn a potential positive stimulus by H 2 O 2 into an inhibitory effect.…”

Differential Effects of Catalase on Apoptosis Induction in Human Promonocytic Cells. Relationships with Heat-Shock Protein Expression

“…On the one hand, cell treatment with H 2 O 2 causes HSF1 activation; on the other hand, H 2 O 2 may inhibit in vitro the HSF1-DNA binding reaction (JacquierSarlin and Polla, 1996;Jornot et al, 1997). Our results indicating that catalase inhibits HSF1-HSE binding and, consequently, HSP synthesis are in agreement with earlier results in other cell models (Nishizawa et al, 1999;Ozaki et al, 2000) and corroborate the importance of H 2 O 2 as a regulator of the stress response.…”

Tumor necrosis factor activates CRE-binding protein through a p38 MAPK/MSK1 signaling pathway in endothelial cells

“…TNF modulates the DNA-binding activity of CRE-binding proteins (36), a group of related transcription factors that includes CREB, in human endothelial cells. However, the signaling pathway through which TNF induces CREB DNA binding and whether this leads to increased transactivation of CREB in endothelial cells has not been determined.…”

“…Considering the important role of TNF in metabolic changes associated with invasive stimuli and alterations of cell growth (70) and its significant effects on endothelial cells, we decided to test whether TNF affects the activity of CREB in human umbilical vein endothelial cells (HUVEC) and, if so, to characterize the mechanism through which such activation is affected. The possibility that TNF might affect CREB was suggested to us by a previous report showing that TNF induces CREB DNA binding (36). However, phosphorylation of CREB on serine 133 increases its transcriptional activity without altering the binding of CREB to CRE.…”