Diverging Parkinson's Disease Pathology between GBAN370S ,LRRK2G2019S and engineered SNCAA53T iPSC-derived Dopaminergic Neurons

Multiple neurodegenerative disorders, including Parkinsons disease (PD) and Alzheimers disease-associated dementia (ADAD), are linked with dopaminergic (DA) neuron death and a resulting reduction in dopamine levels in the brain. DA neuron degeneration and the risk of developing PD is connected to genetic mutations affiliated with lysosomal function and protein degradation. Accessible human cellular models for PD-relevant genetic mutations are needed to investigate mechanisms of DA cell death and define points of therapeutic intervention. Human induced pluripotent stem cell (iPSC)-derived midbrain DA neurons offer a developmentally and physiologically relevant in vitro model for investigating PD pathogenic mechanisms across genetic backgrounds. In this study, we generated DA neurons using iPSCs from two clinically diagnosed PD patients, one harboring an inherited GBAN370S mutation and the other a mutation in LRRK2G2019S and compared pathophysiology against DA neurons from genetically engineered SNCAA53T iPSCs and its isogenic apparently healthy normal (AHN) iPSCs. Our results present a novel phenotype for GBAN370S and LRRK2G2019S derived DA neurons, showing that they produced and released significantly more dopamine compared to the AHN and SNCAA53T mutant DA neurons. All mutant DA neurons developed deficient glucocerebrosidase (GCase) activity, increased mitochondrial stress, aberrant neuronal activity patterns, and increased -synuclein accumulation. Together these data suggest potentially divergent origins of PD pathogenesis in GBAN370S and LRRK2G2019S DA neurons. In addition, compound screening confirmed that GCase modulators can rescue enzyme activity and impact neural activity across all DA mutant neurons, to varying degrees. These data demonstrate unique in vitro phenotypes associated with PD and suggest a diversity of underlying mechanisms across different genetic backgrounds. Together, the cell lines used in this study present a valuable tool for new therapeutic discovery.