The LRRK2 G2019S variant rewires Rab GTPase phosphorylation after lysosomal damage and promotes cell death in human macrophages
ABSTRACT Variants in leucine-rich repeat kinase 2 (LRRK2) are the most common genetic cause of Parkinson's disease, yet how these variants alter immune cell function remains unclear. Because LRRK2 is activated by lysosomal damage in macrophages, we investigated how the pathogenic G2019S variant affects macrophage responses to lysosomal damage. Here, we show that LRRK2 G2019S has an effect during lysosomal damage through kinase-dependent and kinase-independent mechanisms. Phosphoproteomic analysis revealed that lysosomal damage induces selective rewiring of LRRK2-dependent Rab GTPase phosphorylation, characterised by increased Rab12 phosphorylation and reduced Rab35 phosphorylation without global kinase hyperactivation. Strikingly, LRRK2 G2019S macrophages showed increased susceptibility to apoptosis following lysosomal damage. This increase in cell death occurred independently of the kinase activity, indicating a distinct kinase-independent role of LRRK2 in regulating cell survival. We generated isogenic induced pluripotent stem cells from patients carrying the LRRK2 G2019S variant and confirmed that LRRK2 G2019S macrophages are more susceptible to cell death in a kinase-independent manner. Together, our findings support a model in which the LRRK2 G2019S variant selectively changes the phosphorylation of Rab GTPases in macrophages and increases cell death after lysosomal damage in macrophages.