Pathways Disrupted in Human ALS Motor Neurons Identified through Genetic Correction of Mutant SOD1

Abstract

Summary Although many distinct mutations in a variety of genes are known to cause Amyotrophic Lateral Sclerosis (ALS), it remains poorly understood how they selectively impact motor neuron biology and whether they converge on common pathways to cause neuronal degeneration. Here, we have combined reprogramming and stem cell differentiation approaches with genome engineering and RNA sequencing to define the transcriptional and functional changes that are induced in human motor neurons by mutant SOD1. Mutant SOD1 protein induced a transcriptional signature indicative of increased oxidative stress, reduced mitochondrial function, altered sub-cellular transport as well as activation of the ER stress and unfolded protein response pathways. Functional studies demonstrated that these pathways were perturbed in a manner dependent on the SOD1 mutation. Finally, interrogation of stem cell-derived motor neurons produced from ALS patients harboring a repeat expansion in C9orf72 indicates at least a subset of these changes are more broadly conserved in ALS.

αCAR IGF‐1 vector targeting of motor neurons ameliorates disease progression in ALS mice

“…Combinatorial gene therapy utilizing multicistronic LV vectors expressing additional factors, such as heat shock proteins49 or miR‐206,50 could further enhance the potency of this approach. As the aCAR antibody expressed on the LV surface binds both mouse and human receptors51 testing in iPSC‐derived motor neurons from ALS52 patients could be possible and might enhance translatability.…”

A perspective on stem cell modeling of amyotrophic lateral sclerosis

“…Motor neurons carrying the SOD1 A4V mutation showed reduced survival compared with control motor neurons. 25 These patient derived motor neurons exhibited several known phenotypic changes previously associated with ALS, which included neurite degeneration, reduced soma size and disturbed mitochondrial morphology. 25 These findings were absent in control motor neurons in which this mutation was genetically corrected.…”

“…25 These patient derived motor neurons exhibited several known phenotypic changes previously associated with ALS, which included neurite degeneration, reduced soma size and disturbed mitochondrial morphology. 25 These findings were absent in control motor neurons in which this mutation was genetically corrected. 25 Moreover, induction of the ER stress and the unfolded protein response (UPR) pathways was found in these SOD1 mutant motor neurons.…”

“…25 These findings were absent in control motor neurons in which this mutation was genetically corrected. 25 Moreover, induction of the ER stress and the unfolded protein response (UPR) pathways was found in these SOD1 mutant motor neurons. Insoluble SOD1 protein accumulated upon proteasome inhibitor induced stress.…”

“…Insoluble SOD1 protein accumulated upon proteasome inhibitor induced stress. 25 Additionally, these SOD1 mutant motor neurons had more spontaneous electrophysiological activity compared to controls, an affect that could be reversed by treatment with retigabine, a kV7 channel activator. 26 This hyperexcitability was similar to that previously reported in primary wildtype rat spinal cord slices which were treated with conditioned media derived from SOD1G93A primary murine glia.…”