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Redox-Regulated Pathway of Tyrosine Phosphorylation Underlies NF-κB Induction by an Atypical Pathway Independent of the 26S Proteasome
Alternative redox stimuli such as pervanadate or hypoxia/reoxygenation, induce transcription factor NF-κB by phospho-tyrosine-dependent and proteasome-independent mechanisms. While considerable attention has been paid to the absence of proteasomal regulation of tyrosine phosphorylated IκBα, there is...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4384113/ https://www.ncbi.nlm.nih.gov/pubmed/25671697 http://dx.doi.org/10.3390/biom5010095 |
Sumario: | Alternative redox stimuli such as pervanadate or hypoxia/reoxygenation, induce transcription factor NF-κB by phospho-tyrosine-dependent and proteasome-independent mechanisms. While considerable attention has been paid to the absence of proteasomal regulation of tyrosine phosphorylated IκBα, there is a paucity of information regarding proteasomal regulation of signaling events distinct from tyrosine phosphorylation of IκBα. To delineate roles for the ubiquitin-proteasome pathway in the phospho-tyrosine dependent mechanism of NF-κB induction, we employed the proteasome inhibitor, Aclacinomycin, and the phosphotyrosine phosphatase inhibitor, pervanadate (PV). Results from these studies demonstrate that phospho-IκBα (Tyr-42) is not subject to proteasomal degradation in a murine stromal epithelial cell line, confirming results previously reported. Correspondingly, proteasome inhibition had no discernable effect on the key signaling intermediaries, Src and ERK1/2, involved in the phospho-tyrosine mechanisms regulating PV-mediated activation of NF-κB. Consistent with previous reports, a significant redox imbalance leading to the activation of tyrosine kinases, as occurs with pervanadate, is required for the induction of NF-κB. Strikingly, our studies demonstrate that proteasome inhibition can potentiate oxidative stress associated with PV-stimulation without impacting kinase activation, however, other cellular implications for this increase in intracellular oxidation remain to be fully delineated. |
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