Proteomics of motor neuron in ASL model sorted by FACS

Amyotrophic lateral sclerosis (ALS), the most common form of motor neuron disease, is characterized by progressive muscle weakness and paralysis caused by degeneration of upper and lower motor neurons. A major breakthrough in understanding the genetics of ALS was the discovery of a GGGGCC hexanucleotide repeat expansion (HRE) within the non-coding region of chromosome 9 open reading frame 72 (C9orf72) as the most common mutation in both familial and sporadic forms of ALS [25, 80]. We report that C9orf72 loss of function and poly(GP) expression act together to induce motor neuron degeneration and paralysis. These synergistic properties of C9orf72 mutation affect autophagy, thus resulting in poly(GP) and p62 aggregation. In this context, poly(GP) accumulation occurs in motor neurons preferentially, along with swollen mitochondria, a typical signature of mitophagy defects. In motor neurons, accumulated abnormal mitochondria engage caspase cascade, ultimately giving rise to apoptotic cell death of motor neurons that results in paralysis