Protein Stability of Mitochondrial Superoxide Dismutase SOD2 is Regulated by USP36

SOD2 is a key mitochondrial antioxidant enzyme and its perturbation leads to oxidative cell death, which results in various disorders. In this study, we identified a deubiquitinating enzyme USP36 that regulates the protein stability of SOD2. The regulatory effect of USP36 on SOD2 was initially identified by 2-DE and MALDI-TOF/MS analyses. In addition, endogenous USP36 and SOD2 were shown to interact in an immunoprecipitation assay, which was verified using the yeast two-hybrid system. Furthermore, we demonstrated that SOD2 binds with ubiquitin molecules to form polyubiquitination chains and undergoes degradation through the ubiquitin-proteasomal pathway. Finally, USP36 was shown to be a specific deubiquitinating enzyme that reduces the ubiquitination level of SOD2 and was involved in SOD2 protein stability by extending its half-life. J. Cell. Biochem. 112: 498-508, 2011. (C) 2010 Wiley-Liss, Inc.