Interleukin-1beta induction of NFkappaB is partially regulated by H2O2-mediated activation of NFkappaB-inducing kinase.
Reactive oxygen species (ROS) have been demonstrated to act as second messengers in a number of signal transduction pathways, including NFkappaB. However, the mechanism(s) by which ROS regulate NFkappaB remain unclear and controversial. In the present report, we describe a mechanism whereby interleukin-1beta (IL-1beta) stimulation of NFkappaB is partially regulated by H2O2-mediated activation of NIK and subsequent NIK-mediated phosphorylation of IKKalpha. IL-1beta induced H2O2 production in MCF-7 cells and clearance of this ROS through the expression of GPx-1 reduced NFkappaB transcriptional activation by inhibiting NIK-mediated phosphorylation of IKKalpha. Although IKKalpha and IKKbeta were both involved in IL-1beta-mediated activation of NFkappaB, only the IKKalpha-dependent component was modulated by changes in H2O2 levels. Interestingly, in vitro reconstitution experiments demonstrated that NIK was activated by a very narrow range of H2O2 (1-10 microM), whereas higher concentrations (100 microM to 1 mM) inhibited NIK activity. Treatment of cells with the general Ser/Thr phosphatase inhibitor (okadaic acid) lead to activation of NFkappaB and enhanced NIK activity as a IKKalpha kinase, suggesting that ROS may directly regulate NIK through the inhibition of phosphatases. Recruitment of NIK to TRAF6 following IL-1beta stimulation was inhibited by H2O2 clearance and Rac1 siRNA, suggesting that Rac-dependent NADPH oxidase may be a source of ROS required for NIK activation. In summary, our studies have demonstrated that redox regulation of NIK by H2O2 is mechanistically important in IL-1beta induction of NFkappaB activation.
Li
Qiang
Q
Department of Anatomy & Cell Biology, College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA.
Engelhardt
John F
JF
D001943:Breast Neoplasms; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D005260:Female; D017930:Genes, Reporter; D005822:Genetic Vectors; D005979:Glutathione Peroxidase / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007375:Interleukin-1 / Q000494:pharmacology*; D016328:NF-kappa B / Q000096:biosynthesis*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D000097782:NF-kappaB-Inducing Kinase
D005979:Glutathione Peroxidase; D006861:Hydrogen Peroxide; D007375:Interleukin-1; D016328:NF-kappa B; D017346:Protein Serine-Threonine Kinases; D000097782:NF-kappaB-Inducing Kinase