Skeletal muscle TDP-43 aggregation drives progressive motor dysfunction and neurodegeneration with potential for functional recovery after clearance

Abstract

Understanding the mechanisms driving TDP-43 pathology is essential for combating amyotrophic lateral sclerosis and other neurodegenerative diseases. To investigate the contribution of skeletal muscle to disease onset, progression, and recovery, we generated an inducible, muscle-specific TDP-43 mouse model. Cytoplasmic aggregation of exgogenous human TDP-43 protein in skeletal muscle led to muscle dysfunction, denervation, motor neuron loss, and dysregulation of mRNA markers related to myogenesis and neuromuscular junction stress at disease early-stage, along with muscle atrophy, neurodegeneration, and fatal motor decline at disease late-stage. Notably, this endogenous TDP-43 propagated from skeletal muscle to the spinal cord and brain, underscoring the vulnerability of the central nervous system to muscle-derived TDP-43 toxicity. Suppression of cytoplasmic TDP-43 in skeletal muscle improved survival and promoted substantial recovery of muscle dysfunction, motor deficits and neurodegeneration. These findings highlight the therapeutic potential of targeting skeletal muscle-derived TDP-43 toxicity as an approach to delaying neurodegenerative disease.