Involvement of DNA Damage Response via the Ccndbp1–Atm–Chk2 Pathway in Mice with Dextran-Sodium-Sulfate-Induced Colitis

The dextran sodium sulfate (DSS)-induced colitis mouse model has been widely utilized for human colitis research. While its mechanism involves a response to double-strand deoxyribonucleic acid (DNA) damage, ataxia telangiectasia mutated (Atm)–checkpoint kinase 2 (Chk2) pathway activation related to such response remains unreported. Recently, we reported that cyclin D1-binding protein 1 (Ccndbp1) activates the pathway reflecting DNA damage in its knockout mice. Thus, this study aimed to examine the contribution of Ccndbp1 and the Atm–Chk2 pathway in DSS-induced colitis. We assessed the effect of DSS-induced colitis on colon length, disease activity index, and histological score and on the Atm–Chk2 pathway and the subsequent apoptosis in Ccndbp1-knockout mice. DSS-induced colitis showed distal colon-dominant Atm and Chk2 phosphorylation, increase in TdT-mediated dUTP-biotin nick end labeling and cleaved caspase 3-positive cells, and histological score increase, causing disease activity index elevation and colon length shortening. These changes were significantly ameliorated in Ccndbp1-knockout mice. In conclusion, Ccndbp1 contributed to Atm–Chk2 pathway activation in the DSS-induced colitis mouse model, causing inflammation and apoptosis of mucosal cells in the colon.