Mutant TDP-43 Expression Triggers TDP-43 Pathology and Cell Autonomous Effects on Primary Astrocytes: Implications for Non-cell Autonomous Pathology in ALS.

Motor neuron degeneration in amyotrophic lateral sclerosis (ALS) caused by mutations in superoxide dismutase 1 (SOD1) is partly non-cell autonomous, involving cellular dysfunction of astrocytes. Whether non-cell autonomous effects occur in other forms of ALS, such as TAR DNA binding protein 43 (TDP-43)-related disease, remains unclear. Here, we characterised the impact of mutant TDP-43 expression on primary astrocytes derived from transgenic TDP-43 mice. Mutant TDP-43 astrocytes revealed evidence for TDP-43 pathology, shown by cytoplasmic TDP-43 inclusions and accumulation in insoluble cell fractions which was exacerbated by proteasomal inhibition. L-glutamate uptake, measured using an [H]D-aspartate assay, was impaired in mutant TDP-43 astrocytes, while ATP accumulation was abnormal, suggesting mutant TDP-43 induced astrocytic dysfunction. Astrocyte activation coupled with spinal and cortical motor neuron loss in transgenic TDP-43 mice could imply non-cell autonomous effects of astrocytes in vivo. These data demonstrate mutant TDP-43-mediated cell autonomous effects on astrocytes that may contribute to motor neuron pathology in ALS.