Interplay between H3K36me3, methyltransferase SETD2, and mismatch recognition protein MutSa facilitates processing of oxidative DNA damage in human cells.

Oxidative DNA damage contributes to aging and the pathogenesis of numerous human diseases including cancer. 8-hydroxyguanine (8-oxoG) is the major product of oxidative DNA lesions. Although OGG1-mediated base excision repair is the primary mechanism for 8-oxoG removal, DNA mismatch repair has also been implicated in processing oxidative DNA damage. However, the mechanism of the latter is not fully understood. Here, we treated human cells defective in various 8-oxoG repair factors with H2O2 and performed biochemical, live cell imaging, and chromatin immunoprecipitation sequencing analyses to determine their response to the treatment. We show that the mismatch repair processing of oxidative DNA damage involves cohesive interactions between mismatch recognition protein MutSa, histone mark H3K36me3, and H3K36 trimethyltransferase SETD2, which activates the ATM DNA damage signaling pathway. We found that cells depleted of MutSa or SETD2 accumulate 8-oxoG adducts and fail to trigger H2O2-induced ATM activation. Furthermore, we show that SETD2 physically interacts with both MutSa and ATM, which suggests a role for SETD2 in transducing DNA damage signals from lesion-bound MutSa to ATM. Consistently, MutSa and SETD2 are highly coenriched at oxidative damage sites. The data presented here support a model wherein MutSa, SETD2, ATM, and H3K36me3 constitute a positive feedback loop to help cells cope with oxidative DNA damage. [ABSTRACT FROM AUTHOR]