Crucial role of the amino-terminal tyrosine residue 42 and the carboxyl-terminal PEST domain of I kappa B alpha in NF-kappa B activation by an oxidative stress.
Activation of transcription factor NF-kappa B involves the signal-dependent degradation of basally phosphorylated inhibitors such as I kappa B alpha. In response to proinflammatory cytokines or mitogens, the transduction machinery has recently been characterized, but the activation mechanism upon oxidative stress remains unknown. In the present work, we provide several lines of evidence that NF-kappa B activation in a T lymphocytic cell line (EL4) by hydrogen peroxide (H2O2) did not involve phosphorylation of the serine residues 32 and 36 in the amino-terminal part of I kappa B alpha. Indeed, mutation of Ser32 and Ser36 blocked IL-1 beta- or PMA-induced NF-kappa B activation, but had no effect on its activation by H2O2. Although I kappa B alpha was phosphorylated upon exposure to H2O2, tyrosine residue 42 and the C-terminal PEST (proline-glutamic acid-serine-threonine) domain played an important role. Indeed, mutation of tyrosine 42 or serine/threonine residues of the PEST domain abolished NF-kappa B activation by H2O2, while it had no effect on activation by IL-1 beta or PMA-ionomycin. This H2O2-inducible phosphorylation was not dependent on I kappa B kinase activation, but could involve casein kinase II, because an inhibitor of this enzyme (5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole) blocks NF-kappa B activation. H2O2-induced I kappa B alpha phosphorylation was followed by its degradation by calpain proteases or through the proteasome. Taken together, our findings suggest that NF-kappa B activation by H2O2 involves a new mechanism that is totally distinct from those triggered by proinflammatory cytokines or mitogens.
Schoonbroodt
S
S
Laboratory of Virology, Institute of Pathology, University of Liege, Liege, Belgium.
Ferreira
V
V
Best-Belpomme
M
M
Boelaert
J R
JR
Legrand-Poels
S
S
Korner
M
M
Piette
J
J
D000818:Animals; D002154:Calpain / Q000502:physiology; D047390:Casein Kinase II; D003546:Cysteine Endopeptidases / Q000502:physiology; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins; D051379:Mice; D009097:Multienzyme Complexes / Q000502:physiology; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018384:Oxidative Stress; D010446:Peptide Fragments / Q000235:genetics / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D017354:Point Mutation / Q000187:drug effects; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000502:physiology*; D012694:Serine / Q000235:genetics; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D009097:Multienzyme Complexes; D016328:NF-kappa B; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; D010446:Peptide Fragments; D000072000:NF-KappaB Inhibitor alpha; D014443:Tyrosine; D012694:Serine; D004247:DNA; D006861:Hydrogen Peroxide; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; C496564:Chuk protein, mouse; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; C496562:Ikbkb protein, mouse; C496566:Ikbke protein, mouse; C516738:PTPN12 protein, human; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases; C516739:Ptpn12 protein, mouse; D002154:Calpain; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex