CHD8 regulates genomic stability of HSPCs by restricting the ATM-p53 pathway. (A) Western blot of p-P53 S15, acetyl-P53 K379, and damage-response proteins in Lin⁻cKit⁺ cells of WT and Chd8^−/− mice. (B) Increased DNA damage response cannot be rescued by additional loss of P53. (C) Immunofluorescence staining of γH2A.X showed increased DNA damage foci in LSK cells after loss of CHD8. Etoposide treatment for 1 hour. The graph shows the mean ± standard error of the mean of 3 biological replicates. **P < .01. (D) CHD8-deficient cells are more sensitive to irradiation-induced DNA damage. Lin⁻cKit⁺ cells were irradiated at a dose of 3 Gy and harvested after various recovery times. NT, no treatment. (E) Colocalization of BRCA1 and γH2A.X in WT and Chd8^−/− LSK cells. Etoposide treatment for 1 hour. (F) ATM inhibitor KU55933 treatment decreased the P53 and p-P53 in CHD8-depleted HSPCs. Cells were harvested after 3 hours of treatment. (G) CHD8 interacts with ATM in HPC7 cells. (H) CHD8 immunoprecipitation under irradiation in HPC7 cells. The relative ATM pulldown level is normalized to that of the CHD8 pulldown level and represents data from 3 biological repeats. **P < .01. (I) Model of CHD8’s function in restricting P53 signaling and maintaining genomic integrity in HSPCs. The figure was created with BioRender (https://biorender.com/).