Genome-wide association study identifiesAPOEandZMIZ1variants as mitophagy modifiers in Lewy body disease

AbstractThe PINK1-PRKN pathway mediates a critical quality control to maintain mitochondrial health and function. Together the kinase-ligase pair identifies and decorate damaged mitochondria with phosphorylated ubiquitin (p-S65-Ub). This selective label serves as the mitophagy tag and facilitates their degradation via autophagy-lysosome system. While complete loss of PINK1 or PRKN function causes early-onset Parkinson disease, much broader mitophagy impairments are emerging across neurodegenerative disorders. We previously found age- and disease-dependent accumulation of p-S65-Ub signal in the hippocampus of autopsy brains with Lewy body disease (LBD). However, the contribution of genetic variation to mitochondrial damage and p-S65-Ub levels remains unknown in LBD cases. To identify novel regulators of PINK1-PRKN mitophagy in LBD, we performed an unbiased genome-wide association study of hippocampal p-S65-Ub level with 1,012 autopsy confirmed LBD samples. Using an established, mostly automated workflow, hippocampal sections were immunostained for p-S65-Ub, scanned, and quantified with unbiased algorithms. Functional validation of the significant hit was performed in animal model and human induced pluripotent stem cells (hiPSCs).We identified a strong association with p-S65-Ub forAPOE4(rs429358;β: 0.50, 95% CI: 0.41 to 0.69;p=8.67x10-25) and a genome-wide significant association forZMIZ1(rs6480922;β: -0.33, 95% CI: -0.45 to -0.22;p=1.42x10-8). The increased p-S65-Ub levels inAPOE4-carrier may be mediated by both co-pathology-dependent and -independent mechanisms, which was confirmed in Apoe-targeted replacement mice and hiPSC-derived astrocytes. Intriguingly,ZMIZ1rs6480922 also significantly associated with increased brain weight and reduced neuropathological burden indicating a potential role as a resilience factor. Our findings nominate novel mitophagy regulators in LBD brain (ZMIZ1locus) and highlight a strong association ofAPOE4with mitophagy alteration. WithAPOE4being the strongest known risk factor for clinical Alzheimer’s disease and dementia with Lewy bodies, our findings suggest a common mechanistic link underscoring the importance of mitochondrial quality control.