The Neurodevelopmental Consequences of Genomic Stress

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ABSTRACT: The abnormal accumulation of DNA damage in neurons is a shared pathological feature among neurodegenerative diseases (Alzheimer's disease, Parkinson's disease) and it is also correlated with normal aging. Transgenic mouse models further demonstrate a specific requirement for DNA repair during neurogenesis. It is also known that genomic stress, arising from ongoing transcription and metabolic byproducts, plays a role in aging because it contributes to the accumulation of DNA damage. Previously, studying aging in the human brain has been incredibly challenging; post-mortem tissue is difficult to acquire and is not amenable to longitudinal studies. Furthermore, studies of aging have typically looked at model organisms later in life, meaning that few have assessed how stress exposure impacts the development of the brain and how that ultimately affects the aging process. With the development of human-induced pluripotent stem cells (hiPSCs), we now have an in vitro model of human neurodevelopment that provides a tool to study models of normal and pathological neurodevelopment. The goal of this study is to determine how genomic stress and subsequent DNA damage alters the diversity among hiPSC-derived neural progenitor cells (NPCs) and their progeny. Aim one seeks to determine how NPCs are resistant to replicative stress and whether this resistance is unique to NPCs compared to isogenic fibroblasts, astrocytes, and neurons. Multispectral imaging flow cytometry, immunoblotting, and cell cycle analysis will all be used to elucidate the mechanisms of resistance by investigating DNA damage repair proteins. This aim is founded on preliminary data indicating that NPCs are resistant to replication stress and particularly susceptible to transcription associated genomic stress; showing an increase in DNA damage, cell cycle arrest, and DNA damage signaling activation. Aim two seeks to determine if genomic stress promotes neuroinflammatory phenotypes through single cell RNA-seq and the human Luminex assay. hiPSC-based neurogenesis provides a human model system to understand genomic stress related mechanisms in aging and neurodegeneration. This study will define how neurodevelopmental stress may predispose subsets of neurons for later neurodegeneration through neuroinflammatory phenotypes, and ultimately lead to consequent studies focused on protecting NPCs and their progeny from genomic stress to prevent accelerated aging and neurodegenerative disease.