Mitochondrial and Clearance Impairment in p.D620N VPS35 Patient-Derived Neurons

Background VPS35 is part of the retromer complex and is responsible for the trafficking and recycling of proteins implicated in autophagy and lysosomal degradation, but also takes part in the degradation of mitochondrial proteins via mitochondria-derived vesicles. The p.D620N mutation of VPS35 causes an autosomal-dominant form of Parkinson's disease (PD), clinically representing typical PD. Objective Most of the studies on p.D620N VPS35 were performed on human tumor cell lines, rodent models overexpressing mutant VPS35, or in patient-derived fibroblasts. Here, based on identified target proteins, we investigated the implication of mutant VPS35 in autophagy, lysosomal degradation, and mitochondrial function in induced pluripotent stem cell-derived neurons from a patient harboring the p.D620N mutation. Methods We reprogrammed fibroblasts from a PD patient carrying the p.D620N mutation in the VPS35 gene and from two healthy donors in induced pluripotent stem cells. These were subsequently differentiated into neuronal precursor cells to finally generate midbrain dopaminergic neurons. Results We observed a decreased autophagic flux and lysosomal mass associated with an accumulation of alpha-synuclein in patient-derived neurons compared to controls. Moreover, patient-derived neurons presented a mitochondrial dysfunction with decreased membrane potential, impaired mitochondrial respiration, and increased production of reactive oxygen species associated with a defect in mitochondrial quality control via mitophagy. Conclusion We describe for the first time the impact of the p.D620N VPS35 mutation on autophago-lysosome pathway and mitochondrial function in stem cell-derived neurons from an affected p.D620N carrier and define neuronal phenotypes for future pharmacological interventions. (c) 2020 International Parkinson and Movement Disorder Society

Automated summary

This study investigated the impact of the p.D620N VPS35 mutation on autophagy-lysosome pathway and mitochondrial function in induced pluripotent stem cell-derived neurons from a patient. Results showed decreased autophagic flux and lysosomal mass, accumulation of alpha-synuclein, and mitochondrial dysfunction in patient-derived neurons. This provides novel insights for potential pharmacological interventions targeting these pathways in Parkinson's disease.