Deubiquitinating Enzyme USP12 Regulates the Pro-Apoptosis Protein Bax

Abstract

The Bax protein is a pro-apoptotic protein belonging to the Bcl-2 family, involved in inducing apoptosis at the mitochondrial level. Regulating the protein levels of Bax is essential to enhancing apoptosis. In the current study, we ascertained the presence of deubiquitinating enzymes (DUBs) associated with Bax by performing the yeast two-hybrid screening (Y2H). We determined that ubiquitin-specific protease 12 (USP12), one of the DUBs, is associated with Bax. The binding of USP12 to Bax shows the interaction as a DUB, which regulates ubiquitination on Bax. Taken together, we believe that USP12 regulates Bax by detaching ubiquitin on K63-linked chains, indicating that USP12 affects the cellular functions of Bax, but it is not related with proteasomal degradation. The half-life of the Bax protein was determined by performing the site-directed mutagenesis of putative ubiquitination sites on Bax (K128R, K189R, and K190R). Of these, Bax (K128R and K190R) showed less ubiquitination; therefore, we compared the half-life of Bax (WT) and Bax K mutant forms in vitro. Interestingly, Bax (K189R) showed a higher ubiquitination level and shorter half-life than Bax (WT), and the (K128R and K190R) mutant form has a longer half-life than Bax (WT).

Comprehensive review of Bcl‐2 family proteins in cancer apoptosis: Therapeutic strategies and promising updates of natural bioactive compounds and small molecules

“…Consequently, the ubiquitin/proteasome system‐dependent degradation of BAD contributes to the regulation of its proapoptotic activity. Similarly, the ubiquitin–proteasome system controls BAX degradation, which supports cell survival (Choi et al, 2022). Normally, the common isoform of BAX (21 kDa) is a stable molecule.…”

Hovenia dulcis: a Chinese medicine that plays an essential role in alcohol-associated liver disease

“…), increasing the permeability of the cell membrane ( Matsuyama et al, 2016 ). Cytochrome c exists on the inner membrane and then translocates to the cytoplasm ( Choi et al, 2022 ). Bax initiates the intrinsic apoptotic pathway and triggers the release of cytochrome c, which then causes a series of caspase cascade reactions that induce apoptosis ( Matsuyama et al, 2016 ).…”

Spotlights on ubiquitin-specific protease 12 (USP12) in diseases: from multifaceted roles to pathophysiological mechanisms

“…The polyubiquitin chains shaped in Bax are located at k48 and k63, while USP12-mediated deubiquitination acts at the k63 but not the k48 site. Interestingly, although USP12 has deubiquitinating enzymatic activity towards Bax, it cannot regulate its protein expression level [ 69 ]. The mechanisms underlying the influence of USP12 on apoptosis have also been researched in some other diseases, such as cardiac hypertrophy, prostate cancer, and hepatocellular carcinoma [ 63 , 64 , 68 ].…”