Ubiquitin‐Specific Protease 24 Regulates Apoptosis through Deubiquinating Bax and Mediating Ku70 Acetylation

Ubiquitin-specific protease (USP) 24 is one of deubiquinating enzymes (DUBs), which remove polyubiquitin chains from protein substrates and thereby prevent the substrates from ubiquitin-mediated proteasomal degradation. However, little is so far known about the possible role of USP24 in control of protein deubiquitination or in physiological function. In this study, we used a time-lapse technique to observe U2OS cells, and we found that USP24 overexpression caused cell death and increased the detection of caspase-3 cleavage revealed that apoptosis occurred. Furthermore, we we showed that USP24 specifically interacted with and deubiquitinated Bax. USP24 stabilized Bax protein levels, which required its deubiquitinase activity. Moreover, a yeast two-hybrid screening of a human cDNA library was performed to identify potential USP24 cellular partners. We identified a nonhomologous end-joining (NHEJ) factor, Ku70, as a likely USP24-interacting partner. The Ku70 protein was shown to be involved in multiple cell...