Fig. 7. C9orf72 deficiency impairs NHEJ repair to induce DNA damage accumulation in poly-GR expression mice.

a–c C9orf72 deficiency attenuated NHEJ repair in neurons. The brain slices from mice of indicated genotypes were stained with anti-pDNA-PKcs (a), anti-XRCC4 (b), and anti-53BP1 (c) antibodies, respectively. Data are mean (n = 9–21 sections of 3 mice; unpaired t-test; *, p < 0.05; **, p < 0.01; ***, p < 0.001). d Accumulated DNA damage in C9orf72^−/−, AAV-GR₅₀ mice. The cortical neurons were separated from cortex with indicated genotypes. DNA damage in neurons was assessed by the comet assay. Quantitative analysis of tail moment. Data are mean (n = 256 cells from 3 independent experiments; unpaired t-test; ***, p < 0.001). e Reduced genomic integrity in the cortex of C9orf72^−/−, AAV-GR₅₀ mice. The genomic DNA was purified from the cortex of indicated genotypes. A 6.3-kb amplicon in Dntt gene was amplified by long amplicon PCR. Quantitative analysis of the long amplicon. Data are mean (n = 3 independent experiments; Two-way ANOVA; *, p < 0.05; **, p < 0.01; ***, p < 0.001).