Induction of Autophagy Prevents Mutant SOD1G93A Related Neurotoxicity in Experimental Models of Amyotrophic Lateral Sclerosis (ALS)

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder resulting from the progressive loss of both upper and lower motor neurons in the cerebral cortex, brainstem, and spinal cord. Currently, there are only two drugs, Riluzole (Rilutek) and Edaravone (Radicava), approved by FDA for ALS treatment. These two drugs are very expensive with only a few months of life extension. So far, there is no cure for ALS. Aberrant protein aggregation in motor neurons is an intracellular hallmark of ALS. The disturbance in protein homeostasis may contribute to the onset and progression of ALS. Autophagy plays an important role in degrading misfolded proteins, thereby preventing their aggregation. Pharmacological manipulation of autophagy has been proposed as a new therapeutic approach for treating ALS. IADB, a novel indole alkaloid derivative, has been reported to exert mitochondrial protection and cardioprotection through its autophagy-modulating potential. Our present study attempted to examine whether IADB has therapeutic potential in SOD1G93A-associated experimental models of ALS. We found that IADB could promote the clearance of SOD1G93A aggregates and reduce the overproduction of mitochondrial reactive oxygen species (mtROS) in motor neuron-like NSC-34 cells transfected with SOD1G93A. We further examined the IADB in a SOD1-G93A mouse model of ALS. Administration of IADB started at the age of 55 days until the end stage of the disease. IADB treatment significantly increased LC3-II levels and decreased human SOD1 levels and p62 expression in the spinal cords of SOD1G93A mice, suggesting that IADB treatment could induce autophagy activation and promote clearance of mutant SOD1 aggregates in this mouse model of ALS. Moreover, IADB treatment could alleviate the activation of microglia and astrocytes and reduce mitochondrial oxidative damage in the spinal cord of SOD1G93A mice. Finally, we demonstrated that IADB treatment could improve motor performance and delay the onset and progression of the disease in a mouse model of ALS. The neuroprotective effects of IADB may mainly originate from its autophagy-promoting property.