Understanding Cell-type Vulnerability and Oxidative Stress Pathology in Parkinson's Disease Using Isogenic Human Dopaminergic Neurons

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Project Summary: Understanding cell-type vulnerability and manipulating oxidative stress pathology in Parkinson’s Disease using isogenic human dopaminergic neurons About one million Americans live with Parkinson’s Disease (PD) which is characterized by progressive loss of subpopulations of nigral midbrain dopaminergic neurons (DNs), leading to motor impairment and other debilitating conditions. Familial PD genes show broad expression in the brain and neurodegeneration in PD can be widespread; however, it is unclear why nigral DNs show such exquisite vulnerability compared to other cell types, including other DN populations. Post-mortem studies suggest that oxidative stress (OS) contributes to familial and sporadic PD. Reactive oxygen species (ROS) are important signaling molecules but high levels of intracellular ROS will damage DNA, lipids and proteins. High energy needs and dopamine metabolism may explain increased ROS, OS and the unique vulnerability of nigral DNs but human-relevant model systems are required to rigorously test this hypothesis. There is an urgent need to develop experimental systems to better understand nigral DN vulnerability, identify novel disease-relevant signaling mechanisms, and improve molecular subtyping and patient stratification. In this supplement we propose to use a recent model that we have developed and apply it to dissect pathological cell-type-specific mechanisms. We have recently developed a 3D culture model integrating induced pluripotent stem cells (iPSCs) derived individual cell types (neurons, astrocytes, oligodendrocytes, endothelial cells to create brain tissue chips. This approach allows us to integrate cells with different genetic backgrounds. To this end, we aim to investigate the cell type specific effects of familial PD genes PARKIN and DJ1 to better understand the role each brain cell type plays to contribute to PD pathology. Specifically, we aim to determine the impact of PARKIN variants in each cell type on oxidative stress in human brain tissue by creating brain tissue chips with PARKIN loss of function mutations in different cell types. We will monitor oxidative stress in the dopaminergic neurons. Additionally, we aim to determine the impact of DJ1 risk variants in each cell type on proteostasis and dopaminergic neuron survival by introducing different cell types with DJ1 loss of function variants. We will measure proteolytic activity and neuronal death as a result of DJ1 loss of function in different cell types. Applying the 3D tissue chip system to PD will allow us to identify the role of each cell type in contributing to PD pathology.