Background: Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease that primarily affects the motor neurons. T cell intracellular antigen 1 (TIA1) is a risk gene for ALS pathogenesis. To elucidate TIA1-mediated disease mechanisms, a mouse model recapitulating clinical and pathological features of ALS is needed. TIA1 mutations are rare in human ALS, and mutations are heterozygous, while this study uses a homozygous TIA1 mutant mouse model to amplify pathogenic effects for experimental tractability. Methods: To explore the mechanisms by which mutant TIA1 causes ALS neurodegeneration, we generated a TIA1 mutant mouse by introducing ALS-causing mutations into the endogenous animal via cytosine base editors. Next, behavioral experiments (open-field and rotarod tests) assessed motor function and analyzed pathologies using morphological assessments. Results: Our TIA1Δ mouse model phenocopies select pivotal features of ALS, including TAR DNA-binding protein 43 (TDP-43) accumulation, motor neuron loss, neuroinflammation in the lumbar spinal cord, and muscle atrophy. Notably, this homozygous mutation design with reduced TIA1 expression differs from human heterozygous TIA1 mutations. Conclusions: This work provides a foundation for understanding the TIA1-ALS relationship and for developing strategies to treat this intractable neurodegenerative disorder. Caution is warranted extrapolating findings to human ALS pathogenesis due to model design differences.
Mao et al. (Fri,) studied this question.