Role of H3K36 methylation in regulating transcription coupled-nucleotide excision repair

We characterized the role of H3K36 methylation in regulating repair of UV damage from the transcribed strand (TS) of yeast genes by the transcription coupled nucleotide excision repair (TC-NER) pathway. TC-NER is triggered when RNA polymerase stalls at UV damage, such as a UV-induced cyclobutane pyrimidine dimer (CPD). During transcription, the histone methyltransferase Set2 methylates histone H3K36, but it is not known if H3K36 methylation regulates TC-NER. Here, we report genome-wide repair maps of UV-induced cyclobutane pyrimidine dimers (CPDs) in yeast cells containing mutants in histone H3K36 (or set2). UV-induced CPD lesions were mapped in yeast cells both immediately after UV damage formation (0hr time point) and following two hours of repair (2hr time point) using the CPD-seq method. Repair of CPD lesions was measured in yeast cells mutated in the histone H3 gene (H3K36A) or a WT control. Repair was also analyzed in rad16∆H3K36A or rad16set2∆ double mutants, which is deficient in the global genomic NER (GG-NER) pathway.

我们表征了H3K36甲基化在酵母基因转录链（transcribed strand, TS）上由转录偶联核苷酸切除修复（transcription coupled nucleotide excision repair, TC-NER）通路调控紫外线损伤修复中的作用。当RNA聚合酶停滞于紫外线诱导的环丁烷嘧啶二聚体（cyclobutane pyrimidine dimer, CPD）等紫外线损伤位点时，便会触发TC-NER。转录过程中，组蛋白甲基转移酶Set2可对组蛋白H3K36进行甲基化修饰，但目前尚不明确H3K36甲基化是否调控TC-NER。本研究针对携带组蛋白H3K36突变（或set2突变）的酵母细胞，报道了紫外线诱导的环丁烷嘧啶二聚体（CPD）的全基因组修复图谱。我们采用CPD测序法（CPD-seq），分别在紫外线损伤形成后即刻（0小时时间点）与修复2小时后（2小时时间点），对酵母细胞内的紫外线诱导CPD损伤位点进行了定位。本研究检测了组蛋白H3基因突变体（H3K36A）酵母细胞与野生型（WT）对照细胞的CPD损伤修复水平。此外，我们还对全局基因组核苷酸切除修复（global genomic NER, GG-NER）通路缺陷的rad16ΔH3K36A或rad16set2Δ双突变体的CPD损伤修复情况进行了分析。