title: Transactivation of gene expression by NF-κB is dependent on thioredoxin reductase activity.
abstract: The redox-sensitive transcription factor NF-κB mediates the expression of genes involved in inflammation and cell survival. Thioredoxin reductase-1 (TR1) and its substrate thioredoxin-1 act together to reduce oxidized cysteine residues within the DNA-binding domain of NF-κB and promote maximal DNA-binding activity in vitro. It is not clear, however, if NF-κB is regulated via this mechanism within living cells. The purpose of this study was to determine the mechanism of NF-κB modulation by TR1 in cells stimulated with the inflammatory cytokine tumor necrosis factor-α (TNF). In both control cells and cells depleted of TR1 activity through chemical inhibition or siRNA knockdown, TNF stimulation resulted in degradation of the cytoplasmic NF-κB inhibitor IκB-α and translocation of NF-κB to the nucleus. Similarly, the DNA-binding activity and redox state of NF-κB were unaffected by TR1 depletion. In contrast, NF-κB-mediated gene expression was markedly inhibited in cells lacking TR1 activity, suggesting that the transactivation potential of NF-κB is sensitive to changes in TR1 activity. Consistent with this concept, phosphorylation of the transactivation domain of NF-κB was inhibited in the presence of curcumin. Surprisingly, another TR1 inhibitor, 1-chloro-2,4-dinitrobenzene, had no effect, and siRNA knockdown of TR1 actually increased phosphorylation at this site. These results demonstrate that TR1 activity controls the transactivation potential of NF-κB and that more than one mechanism may mediate this effect.
authors.affiliation: Division of Toxicology, Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Heilman
authors.forename: Tom J
authors.initials: TJ
authors.lastname: Burke
authors.forename: Craig J
authors.initials: CJ
authors.lastname: McClain
authors.forename: Walter H
authors.initials: WH
authors.lastname: Watson
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D003474:Curcumin / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004137:Dinitrochlorobenzene / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000276:immunology; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D013880:Thioredoxin-Disulfide Reductase / Q000235:genetics / Q000378:metabolism*; D013879:Thioredoxins / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D004137:Dinitrochlorobenzene; D018836:Inflammation Mediators; D016328:NF-kappa B; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D013879:Thioredoxins; D004247:DNA; D013880:Thioredoxin-Disulfide Reductase; D003474:Curcumin