Activation of autophagy attenuates motor deficits and extends lifespan in a C. elegans model of ALS.

Mutations in Cu/Zn-superoxide dismutase 1 (SOD1) are linked to amyotrophic lateral sclerosis (ALS). Using a line of ALS-related mutant human SOD1 (hSOD1) transgenic Caenorhabditis elegans, we determined the effects of metformin on the progression of ALS-like pathological abnormalities. We found that metformin significantly extended the lifespan, improved motor performance, and enhanced antioxidant activity of mutant worms. We further showed that metformin enhanced expression of lgg-1, daf-16, skn-1 and other genes known to regulate autophagy, longevity and oxidative stress in hSOD1 transgenic worms. Accordingly, overexpression of lgg-1 or daf-16 attenuated the aging and pathological abnormalities of mutant human SOD1 worms, while genetic deletion of lgg-1 or daf-16 abolished the beneficial effects of metformin. Collectively, we demonstrate that metformin protects against mutant SOD1-induced cytotoxicity in part through enhancement of autophagy and extends lifespan through daf-16 pathway. Our findings suggest that metformin could be further explored as a potential therapeutic agent in treating ALS.