LRRK2-I1371V Disrupts Astrocyte Membrane Homeostasis and Paradoxically Enhances α-Synuclein Toxicity Despite Impaired Clearance

Astrocyte dysfunction represents a critical pathogenic mechanism in neurodegenerative diseases, particularly through impaired α-synuclein aggregate clearance and aberrant inflammatory responses. Using human iPSC-derived astrocytes carrying the LRRK2-I1371V Parkinson's disease mutation and LRRK2-I1371V-transfected U87-cells, we assessed comprehensive membrane analysis using anisotropy measurements and atomic-force microscopy, membrane composition through lipidomics, and functional assays, to reveal a paradoxical relationship between clearance capacity and cellular vulnerability. LRRK2-I1371V astrocytes exhibited significantly impaired α-synuclein association and uptake through reduced endocytosis, yet paradoxically displayed enhanced cellular toxicity with increased oxidative stress, calcium influx, and pro-inflammatory cytokine release. Mechanistically, LRRK2-I1371V-induced hyperphosphorylation of Rab8A and Rab10 disrupted cholesterol-trafficking pathways, reducing membrane-cholesterol content and destabilizing lipid raft organization. This membrane remodelling facilitated α-synuclein aggregate-induced amyloid pore formation, resulting in excessive calcium influx that triggered rise in ROS, RNS and inflammatory cascades. Our findings fundamentally revise understanding of astrocyte α-synuclein clearance dysfunction, identifying the LRRK2-Rab-cholesterol axis as a novel therapeutic target.