Cholesterol enhances lysosome-autophagosome fusion for better α-synuclein clearance in GBA L444P-mutated Parkinson disease.

Mutations in lysosomal enzyme glucocerebrosidase (GBA), the most common genetic risk factor for Parkinson disease (PD), exacerbate α-synuclein pathology through unclear mechanisms. Here, we report, in a large cohort, that GBA-mutated PD patients exhibit lower serum cholesterol levels. By introducing the most common GBA variant in our cohort, L444P, into human α-synuclein knock-in mice, we noted that the mice exhibited behavioral and molecular pathological PD features at 12 months of age. Mechanistically, lysosomal proteomics identified the loss of lysosome-cytoplasmic vesicle interactions and cholesterol-containing lipid microdomains in both PD patients and mice. Autophagic flux monitoring revealed impaired autophagosome-lysosome fusion in GbaL444P/+ neurons. Gain- and loss-of-function experiments uncovered cholesterol synthesis impairment via glycosphingolipid-reduced SREBP2 levels. Importantly, cholesterol supplementation was found to enhance the autophagic flux and mitigate α-synuclein accumulation in vitro, whereas AAV-Srebp2 delivery increased α-synuclein clearance in GbaL444P/+ mice. Our study provides animal models and mechanistic insights into GBA-associated PD and offers a therapeutic paradigm by facilitating cholesterol-associated α-synuclein autophagic clearance.