Downregulation of endogenous TDP-43 at mRNA and protein level. A: Immunostaining with the TDP-43 antibody that recognizes the C-terminal part of both mouse and human TDP-43 (12892-1-AP) of the ventral horn of the lumbar spinal cord of TDP-43 (A315T) mice at ES (middle and lower panels) compared to NTG mice (upper panels). Loss of nuclear TDP-43 (middle panels, arrows) and (intranuclear) TDP-43 inclusions (lower panels, arrows) could be detected, but were rare. For the pictures, both the separate images and the merged are shown (red: TDP-Ab; green: NeuN; blue: DAPI). Scale bars: 50 μm. B: 20% reduction of the endogenous mouse TDP-43 mRNA in the spinal cord due to the overexpression of exogenous human TDP-43 in the TDP-43 (A315T) mice (p < 0.0001, n = 3 for each genotype). C: 31% reduction of the endogenous mouse TDP-43 mRNA in the brain of TDP-43 (A315T) mice (p < 0.0001, n = 3 for each genotype). D -E (D) Representative Western blot of spinal cord tissue of NTG mice (left), compared to presymptomatic female TDP-43 (A315T) mice (right). The higher band, that is absent in the NTG mice, is the human TDP-43 protein, containing a Flag-tag. Alfa-tubulin was used for normalization (n = 3). E: Quantification showed a 48% loss of endogenous TDP-43. F: Downregulation of the levels of Sort1 with exon 17b inclusion in the brain of the TDP-43 (A315T) mice, compared to NTG mice (n = 3 for each genotype; p = 0.031).