The AKT-USP15 axis modulates autophagy in MPP⁺-induced Parkinson's disease model of SN4741 cells

In Parkinson's disease (PD), maintaining the balance between protein synthesis and degradation is critical for cellular homeostasis. Ubiquitination, which marks proteins for degradation, and its reverse process deubiquitination, are essential regulators for protein turnover. Recent research implicate that deubiquitinating enzymes involve in PD pathogenesis. Specially, Ubiquitin Specific Protease 15 (USP15) has been shown to antagonize Parkin, an E3 ubiquitin ligase that facilitates mitophagy - the selective clearance of damaged mitochondria. However, the regulatory mechanisms governing the activity of USP15 in PD remain unclear. Our study revealed a novel regulatory mechanism: USP15 served as a phosphorylation substrate for protein kinase B (AKT). AKT-mediated phosphorylation triggered translocation of USP15 from the nucleus to the cytoplasm, subsequently restoring autophagy levels. These data identified that AKT mediated phosphorylation of USP15 regulated autophagy in MPP⁺-induced PD models. Collectivelly, our research elucidates the complex interplay among AKT, USP15, and autophagy in PD. These mechanistic insights advance our understanding of potential therapeutic targets to enhance autophagic flux and ameliorate cellular dysfunction in Parkinson's disease.