Mouse DNA polymerase kappa has a functional role in the repair of DNA strand breaks.

The Y-family of DNA polymerases support of translesion DNA synthesis (TLS) associated with stalled DNA replication by DNA damage. Recently, a number of studies suggest that some specialized TLS polymerases also support other aspects of DNA metabolism beyond TLS in vivo. Here we show that mouse polymerase kappa (Pol?) could accumulate at laser-induced sites of damage in vivo resembling polymerases eta and iota. The recruitment was mediated through Pol? C-terminus which contains the PCNA-interacting peptide, ubiquitin zinc finger motif 2 and nuclear localization signal. Interestingly, this recruitment was significantly reduced in MSH2-deficient LoVo cells and Rad18-depleted cells. We further observed that Pol?-deficient mouse embryo fibroblasts were abnormally sensitive to H2O2 treatment and displayed defects in both single-strand break repair and double-strand break repair. We speculate that Pol? may have an important role in strand break repair following oxidative stress in vivo.