Tyrosine phosphorylation of I kappa B alpha activates NF kappa B through a redox-regulated and c-Src-dependent mechanism following hypoxia/reoxygenation.
NF kappa B is a critical transcription factor involved in modulating cellular responses to environmental injuries. Tyrosine 42 phosphorylation of I kappa B alpha has been shown to mediate NF kappa B activation following hypoxia/reoxygenation (H/R) or pervanadate treatment. This pathway differs from the canonical proinflammatory pathways, which mediate NF kappa B activation through serine phosphorylation of I kappa B alpha by the IKK complex. In the present study, we investigated the involvement of c-Src in the redox activation of NFkappaB following H/R or pervanadate treatment. Our results demonstrate that pervanadate or H/R treatment leads to tyrosine phosphorylation of I kappa B alpha and NF kappa B transcriptional activation independent of the IKK pathway. In contrast, inhibition of c-Src by pp2 treatment or in c-Src (-/-) knockout cell lines, demonstrated a significant reduction in I kappa B alpha tyrosine phosphorylation and NF kappa B activation following pervanadate or H/R treatment. Overexpression of glutathione peroxidase-1 or catalase, but not Mn-SOD or Cu,Zn-SOD, significantly reduced both NF kappa B activation and tyrosine phosphorylation of I kappa B alpha. In vitro kinase assays further demonstrated that immunoprecipitated c-Src has the capacity to directly phosphorylate GST-I kappa B alpha and that this I kappa B alpha kinase activity is significantly reduced by Gpx-1 overexpression. These results suggest that c-Src-dependent tyrosine phosphorylation of I kappa B alpha and subsequent activation of NF kappa B is controlled by intracellular H(2)O(2) and defines an important redox-regulated pathway for NF kappa B activation following H/R injury that is independent of the IKK complex.
Fan
Chenguang
C
Molecular Biology Graduate Program, the Department of Anatomy and Cell Biology, University of Iowa, Iowa City, Iowa 52242, USA.
Li
Qiang
Q
Ross
Dan
D
Engelhardt
John F
JF
D000860:Hypoxia / Q000378:metabolism*; D020672:I-kappa B Proteins / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*; D015533:Transcriptional Activation; D014443:Tyrosine / Q000378:metabolism
D020672:I-kappa B Proteins; D016328:NF-kappa B; D000072000:NF-KappaB Inhibitor alpha; D014443:Tyrosine; D016392:Proto-Oncogene Proteins pp60(c-src)