The deubiquitinase USP45 inhibits autophagy through actin regulation by Coronin 1B.

The autophagy-lysosomal system comprises a highly dynamic and interconnected vesicular network that plays a central role in maintaining proteostasis and cellular homeostasis. In this study, we uncovered the deubiquitinating enzyme (DUB), dUsp45/USP45, as a key player in regulating autophagy and lysosomal activity in Drosophila and mammalian cells. Loss of dUsp45/USP45 results in autophagy activation and increased levels of V-ATPase to lysosomes, thus enhancing lysosomal acidification and function. Furthermore, we identified the actin-binding protein Coronin 1B (Coro1B) as a substrate of USP45. USP45 interacts with and deubiquitinates Coro1B, thereby stabilizing Coro1B levels. Notably, the ablation of USP45 or Coro1B promotes the formation of F-actin patches and the translocation of V-ATPase to lysosomes in an N-WASP-dependent manner. Additionally, we observed positive effects of dUsp45 depletion on extending lifespan and ameliorating polyglutamine (polyQ)-induced toxicity in Drosophila. Our findings highlight the important role of dUsp45/USP45 in regulating lysosomal function by modulating actin structures through Coro1B.