An All Optical Platform for Modeling and Monitoring Early Neurodegeneration in Human Neural Circuits

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PROJECT SUMMARY Treatments for neurodegenerative disorders that slow or delay disease onset, mitigate symptoms, and improve patient quality of life are desperately needed. A common feature of neurodegenerative diseases such as Parkinson’s Disease (PD) is synaptic dysfunction and excitatory-inhibitory imbalance. Although traditionally seen as consequences of cell death, emerging research has shown that these processes may occur before widespread degeneration, making them promising targets for the development of neuroprotective therapeutics. Therefore, this project aims to develop new tools to better understand early defects in global neurochemical dynamics, synaptic physiology, and circuit structure in neurodegeneration. A pre-degeneration model of sporadic PD will be established in this project by genetic manipulation of endogenous alpha-synuclein, a central hallmark of the disease (Aim 1). Given the limitations in the translatability of rodent models of PD, this project utilizes human pluripotent stem cell derived neurons organized in functional circuits using a microfluidic culture device. This device allows for not only circuit-specific manipulation of alpha-synuclein, but also the specific maturation and organization of distinct cell types to recapitulate basal ganglia inputs. For high-fidelity and circuit-specific measurements of changes in circuit structure and function in this model, innovations in novel optical tools will be pursued. The optical sensors developed in this proposal utilizes a hybrid chemigenetic strategy that involves a genetically encoded HaloTag based protein scaffold and bright, red- shifted dyes. A far-red hybrid HaloTag-based chemigenetic glutamate sensor will be utilized alongside a calcium indicator and optogenetic actuator to allow for all-optical manipulation and read-out of circuit function in early PD (Aim 2). A split HaloTag-based synaptic sensor will be developed to enable simultaneous measurement of changes in synaptic density and synaptic glutamate transmission with cell type and input specificity (Aim 3). These tools will allow us to test the central hypothesis that circuit-specific manipulation of alpha-synuclein in human cortico-basal ganglia circuitry will result in disparate modulation of glutamate activity, synapse function, and circuit structure. Successful completion of this project will also result in the establishment of a general platform from which other neurodegenerative disorders and therapeutic interventions can be understood.