Selective Silencing of TDP-43 P. G376D Mutation Reverses Key Amyotrophic Lateral Sclerosis-Related Cellular Deficits

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease for which there is currently no cure. Dominant mutations in the <i>TARDBP</i> gene are causative of ALS. In particular, the p. G376D substitution in TDP-43 causes familial ALS and it is associated with TDP-43 mislocalization in the cytosol, increased presence of cytoplasmic aggregates, and lysosomal and mitochondrial dysfunction. We previously designed a small interfering RNA (siRNA) that specifically targets and silences the mutant allele and we demonstrated that, in patient-derived fibroblasts, it can reduce TDP-43 aggregation, decrease oxidative stress, and improve cell viability. Here, we investigated the ability of this siRNA to revert some ALS-associated pathological phenotypes in motor neurons derived from induced pluripotent stem cells (iPSCs), as motor neurons are the primary cells affected in ALS. siRNA treatment reduced TDP-43 mislocalization, enhanced lysosomal function and cell viability, and decreased oxidative stress. These findings indicate that this allele-specific siRNA effectively reverses key ALS-related cellular deficits in motor neurons, representing a promising candidate for targeted therapy in patients carrying the TDP-43 G376D mutation.