Exposure to the organochlorine pesticide cis-chlordane induces ALS-like mitochondrial perturbations in stem cell-derived motor neurons

Amyotrophic Lateral Sclerosis (ALS) is a debilitating and incurable neurodegenerative dis-ease with unsolved etiology. Due to the large proportion of patients lacking direct disease inher-itance, understanding the environmental factors that contribute to ALS development is of high priority. Epidemiological studies have implicated pesticides and other environmental exposures as possible contributors to ALS pathogenesis. Recently, our group determined that the organo-chlorine pesticide cis-chlordane is toxic to human motor neurons in a dose-dependent manner, causing an ALS-like phenotype in culture and animals with a mode of action independent of its known GABAA antagonism. Here, we aimed to characterize downstream motor neuron pheno-types associated with cis-chlordane treatment. We performed bulk RNA sequencing, live imaging, immunofluorescent labeling, and real-time metabolic assays on stem cell-derived motor neurons to assess chlordane-associated phenotypes in vitro. We demonstrate that cis-chlordane treatment causes a highly altered mitochondrial phenotype in motor neurons, including increased produc-tion of reactive oxygen species, decreased oxygen consumption rate and ATP production, and loss of mitochondrial membrane potential. We further implicate cis-chlordane as a possible medi-ator of potent motor neuron damage, with exposure to the pesticide inducing mitochondrial phe-notypes akin to those seen in ALS. We suggest that future studies investigating the role of pesti-cides in ALS development center upon the organochlorine molecules. Overall design: Wild type human embryonic stem cell derived motor neruons, which express GFP when mature (WA09-Islet1-GFP), were treated with either solvent (control) or the pesticide cis-chlordane (Treated) for 16 hours and then FACS purified (GFP pos and GFP neg). The 12 samples, 3 treated GFP pos/neg, and 3 control GFP pos/neg, were then subjected to bulk RNA sequencing.