Loss of TDP-43 in astrocytes leads to motor deficits by triggering A1-like reactive phenotype and tri-glial dysfunctions

The majority of patients with amyotrophic lateral sclerosis (ALS) have abnormal TDP-43 aggregates in the nucleus and/or cytosol of their surviving neurons and glia. Although accumulating evidence indicates that astroglial dysfunctions contribute to motor neuron degeneration in ALS, the normal physiological functions of TDP-43 in astrocytes are largely unknown and whether the loss of astroglial TDP-43 contributes to ALS remains to be clarified. Here, we showed that TDP-43 deleted astrocytes showed cell-autonomously enhanced GFAP immunoreactivity without affecting astrocyte or microglia proliferation. At the transcriptomic level, TDP-43 deleted astrocytes resemble the A1-reactive astrocytes and induce microglia to increase C1q expression. These astrocytic changes do not cause the loss of motor neurons in spinal cords or denervation at the neuromuscular junctions. In contrast, there was a selective reduction of mature oligodendrocytes, but not oligodendrocyte precursor cells, suggesting a tri-glial dysfunction mediated by TDP-43-deleted astrocytes. Mice with astroglial TDP-43 deletion developed motor, but not sensory, deficits. Taken together, our results demonstrate that TDP-43 is required to maintain the protective functions of astrocytes relevant to the development of motor deficits in mice. Differential gene expression analysis of spinal cord sections of 3-month old mice with TDP-43 deleted in astrocytes