Therapeutic modulation of eIF2α-phosphorylation rescues TDP-43 toxicity in amyotrophic lateral sclerosis disease models

Amyotrophic lateral sclerosis (ALS) is a fatal, late-onset neurodegenerative disease primarily impacting motor neurons. A unifying feature of many proteins associated with ALS, including TDP-43 and Ataxin-2, is that they localize to stress granules. Unexpectedly, we found that genes that modulate stress granules are striking modifiers of TDP-43 toxicity in Saccharomyces cerevisiae and Drosophila melanogaster, eIF2α phosphorylation is upregulated by TDP-43 toxicity in flies, and TDP-43 interacts with a central stress granule component polyA binding protein (PABP). In human ALS spinal cord neurons, PABP accumulates abnormally, suggesting that prolonged stress granule dysfunction may contribute to pathogenesis. We investigated the efficacy of a small molecule inhibitor of eIF2α-phosphorylation in ALS models. This treatment mitigated TDP-43 toxicity in flies and mammalian neurons. These findings indicate that dysfunction induced by prolonged stress granule formation may contribute directly to ALS and that compounds that mitigate this process may represent a novel therapeutic approach.