A comparative inter-neuronal and inter-species platform to understand neuronal differential sensitivity to neurodegeneration

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Neurodegenerative diseases are characterized by the selective death of specific neuronal cell types. Although fundamental to understanding neurodegeneration and designing effective therapies, the molecular nature of differential sensitivity to neurodegeneration remains obscure. Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive muscle denervation and loss of motor neurons leading to paralysis. However, not all motor neurons are affected equally. While most spinal motor neurons (SpMNs) degenerate during ALS progression, a subset of rostral cranial motor neurons (CrMNs: oculomotor, trochlear and abducens motor neurons) are typically spared, allowing patients to retain eye movement until late stages of the disease. Thus, ALS patients utilize eye tracking devices to communicate until late disease stages. The ALS resistance seems to be a conserved feature since oculomotor and trochlear motor neurons are also more resistant than SpMNs to neurodegeneration in the ALS mouse model expressing human superoxide dismutase 1 (hSOD1) with G93A mutation. We have established an efficient embryonic stem cell differentiation platform that produces ALS-sensitive and -resistant motor neurons. We have validated the predictive power of this in vitro system with embryonically-derived motor neurons and have identified the ability to maintain a healthy proteome as a possible motor neuron intrinsic mechanism to resist ALS. The goal of this application is to generate a predictive human stem cell differentiation system that will complement model organisms to understand the intrinsic neuronal mechanisms that contribute to motor neuron differential ALS sensitivity to deepen our understanding of ALS pathology and inspire effective therapies.