Persistent mRNA localization defects and cell death in ALS neurons caused by transient cellular stress

Neurodegeneration-associated mutations affect the dynamics of transient cytoplasmic stress granule (SG). However, it is unclear if and how aberrant SG behavior is linked to the downstream formation of protein aggregates and other molecular defects that persist after stress subsides. Using subcellular fractionation combined with RNA-seq (CeFra-seq) we characterize the global mRNA localization landscape in human pluripotent stem cell-derived motor neuron (PS-MN). Using CeFra-seq and quantitative proteomics, we find that transient stress leads to a widespread reshaping of mRNA and protein localization that recapitulates key molecular phenotypes of Amyotrophic Lateral Sclerosis (ALS). While the substantial reorganization of the global mRNA localization landscape is largely reversible in wild type PS-MNs, we find that cells harboring ALS-linked mutations in HNRNPA2B1 are unable to recover and display a delayed-onset increase in neuronal cell death in response to stress. Our findings reaffirm the importance of stress-induced molecular mechanisms in the formation of molecular disease pathology of ALS and highlight the importance of targeting SG-relevant molecular mechanisms in the development of therapeutic strategies. Analysis of global mRNA localization in stem cells, stem cell-derived motor neurons and stem cell-derived motor neurons exposed to cellular stress and/or harboring ALS-associated mutations in HNRNPA2B1