m ⁵C modification of mRNA serves a DNA damage code to promote homologous recombination

Abstract

Recruitment of DNA repair proteins to DNA damage sites is a critical step for DNA repair. Post-translational modifications of proteins at DNA damage sites serve as DNA damage codes to recruit specific DNA repair factors. Here, we show that mRNA is locally modified by m ⁵C at sites of DNA damage. The RNA methyltransferase TRDMT1 is recruited to DNA damage sites to promote m ⁵C induction. Loss of TRDMT1 compromises homologous recombination (HR) and increases cellular sensitivity to DNA double-strand breaks (DSBs). In the absence of TRDMT1, RAD51 and RAD52 fail to localize to sites of reactive oxygen species (ROS)-induced DNA damage. In vitro, RAD52 displays an increased affinity for DNA:RNA hybrids containing m ⁵C-modified RNA. Loss of TRDMT1 in cancer cells confers sensitivity to PARP inhibitors in vitro and in vivo. These results reveal an unexpected TRDMT1-m ⁵C axis that promotes HR, suggesting that post-transcriptional modifications of RNA can also serve as DNA damage codes to regulate DNA repair.

Abstract

Post-translational modifications of proteins at DNA damage sites can facilitate the recruitment of DNA repair factors. Here, the authors show that mRNA is locally modified with m ⁵C at sites of DNA damage by the RNA methyltransferase TRDMT1 to promote homologous recombination repair.