Protein stability of mitochondrial superoxide dismutase SOD2 is regulated by USP36

Abstract 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. © 2010 Wiley‐Liss, Inc.