Pervanadate-induced nuclear factor-kappaB activation requires tyrosine phosphorylation and degradation of IkappaBalpha. Comparison with tumor necrosis factor-alpha.

Cytokine Research Laboratory, Department of Bioimmunotherapy, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Journal of Biological Chemistry (Impact Factor: 4.57). 04/2000; 275(12):8549-55.
Source: PubMed


Tumor necrosis factor activates nuclear transcription factor kappaB (NF-kappaB) by inducing serine phosphorylation of the inhibitory subunit of NF-kappaB (IkappaBalpha), which leads to its ubiquitination and degradation. In contrast, pervanadate (PV) activates NF-kappaB and induces tyrosine phosphorylation of IkappaBalpha (Singh, S., Darney, B. G., and Aggarwal, B. B. (1996) J. Biol. Chem. 271, 31049-31054; Imbert, V., Rupec, R. A., Antonia, L., Pahl, H. L., Traenckner, E. B.-M., Mueller-Dieckmann, C., Farahifar, D., Rossi, B., Auderger, P., Baeuerle, P. A., and Peyron, J.-F. (1996) Cell 86, 787-798). Whether PV also induces IkappaBalpha degradation and whether degradation is required for NF-kappaB activation are not understood. We investigated the effect of PV-induced tyrosine phosphorylation on IkappaBalpha degradation and NF-kappaB activation. PV activated NF-kappaB, as determined by DNA binding, NF-kappaB-dependent reporter gene expression, and phosphorylation and degradation of IkappaBalpha. Maximum degradation of IkappaBalpha occurred at 180 min, followed by NF-kappaB-dependent IkappaBalpha resynthesis. N-Acetylleucylleucylnorlucinal, a proteasome inhibitor, blocked both IkappaBalpha degradation and NF-kappaB activation, suggesting that the IkappaBalpha degradation is required for NF-kappaB activation. PV did not induce serine phosphorylation of IkappaBalpha but induced phosphorylation at tyrosine residue 42. Unlike tumor necrosis factor (TNF), PV did not induce ubiquitination of IkappaBalpha. Like TNF, however, PV induced phosphorylation and degradation of IkappaBalpha, and subsequent NF-kappaB activation, which could be blocked by N-tosyl-L-phenylalanine chloromethyl ketone, calpeptin, and pyrrolidine dithiocarbomate, suggesting a close link between PV-induced NF-kappaB activation and IkappaBalpha degradation. Overall, our studies demonstrate that PV activates NF-kappaB, which, unlike TNF, requires tyrosine phosphorylation of IkappaBalpha and its degradation.

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    • "As with any inhibitor study, the specificity of the inhibitors is key to interpreting results. Of the inhibitors used in the present study, orthovanadate (Gordon, 1991) and peroxyvanadate (Ruff et al., 1997; Mukhopadhyay et al., 2000; Touyz et al., 2001; Shimizu et al., 2001; Mariner et al., 2001) are probably the most specific and have been used extensively for in vivo studies. Calpeptin has recently been identified as a specific PTPase inhibitor (Schoenwaelder and Burridge, 1999; Whitehouse et al., 2000) suitable for use with intact cells. "
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