title: c-Jun NH2-terminal kinase-mediated redox-dependent degradation of IkappaB: role of thioredoxin in NF-kappaB activation.
abstract: NF-kappaB is a redox-sensitive transcription factor known to be activated by oxidative stress as well as chemical and biological reductants. Its DNA binding activity requires reduced cysteines present in the p65 subunit of the dimer. Thioredoxin (Trx) is an endogenous disulfide oxidoreductase known to modulate several redox-dependent functions in the cell. NF-kappaB was activated by addition of Escherichia coli thioredoxin in a redox-dependent manner in A549 cells. Such activation was accompanied by degradation of IkappaB in the cytosol. In addition, only the reduced form of thioredoxin activated NF-kappaB, whereas the oxidized form was without any effect. Overexpression of human thioredoxin also caused activation of NF-kappaB and degradation of IkappaB. On the contrary, dominant-negative redox-inactive mutant thioredoxin expression did not activate NF-kappaB, further confirming the redox-dependent activation of NF-kappaB. We also investigated the mechanism of activation of NF-kappaB by thioredoxin. We demonstrate that thioredoxin activates c-Jun NH(2)-terminal kinase (JNK)-signaling cascade, and dominant-negative expression of mitogen-activated protein kinase kinase kinase 1 (MEKK1), JNK kinase, or JNK inhibits NF-kappaB activation by thioredoxin. In contrast, wild-type MEKK1 or JNK kinase induced NF-kappaB activation alone or in combination with thioredoxin expression plasmid. These findings were also confirmed by NF-kappaB-dependent luciferase reporter gene transcription.
authors.affiliation: Department of Molecular Biology, University of Texas Health Center, Tyler, TX 75708, USA. kumuda@uthct.edu
authors.forename: K C
authors.initials: KC
authors.lastname: Das
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D021581:Active Transport, Cell Nucleus; D001426:Bacterial Proteins / Q000494:pharmacology; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D004926:Escherichia coli; D017930:Genes, Reporter; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D048728:MAP Kinase Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism*; D010084:Oxidation-Reduction; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology; D013879:Thioredoxins / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; C067713:lactacystin; D013879:Thioredoxins; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; D048670:MAP Kinase Kinase 4; C482559:MAP2K4 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; D000111:Acetylcysteine