Xiang Yang, Laurent Benoit, Hsu Chih-Hung, Nachtergaele Sigrid, Lu Zhike, Sheng Wanqiang, Xu Chuanyun, Chen Hao, Ouyang Jian, Wang Siqing, Ling Dominic, Hsu Pang-Hung, Zou Lee, Jambhekar Ashwini, He Chuan, Shi Yang
Division of Newborn Medicine and Epigenetics Program, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Nature. 2017 Mar 23;543(7646):573-576. doi: 10.1038/nature21671. Epub 2017 Mar 15.
Cell proliferation and survival require the faithful maintenance and propagation of genetic information, which are threatened by the ubiquitous sources of DNA damage present intracellularly and in the external environment. A system of DNA repair, called the DNA damage response, detects and repairs damaged DNA and prevents cell division until the repair is complete. Here we report that methylation at the 6 position of adenosine (mA) in RNA is rapidly (within 2 min) and transiently induced at DNA damage sites in response to ultraviolet irradiation. This modification occurs on numerous poly(A) transcripts and is regulated by the methyltransferase METTL3 (methyltransferase-like 3) and the demethylase FTO (fat mass and obesity-associated protein). In the absence of METTL3 catalytic activity, cells showed delayed repair of ultraviolet-induced cyclobutane pyrimidine adducts and elevated sensitivity to ultraviolet, demonstrating the importance of mA in the ultraviolet-responsive DNA damage response. Multiple DNA polymerases are involved in the ultraviolet response, some of which resynthesize DNA after the lesion has been excised by the nucleotide excision repair pathway, while others participate in trans-lesion synthesis to allow replication past damaged lesions in S phase. DNA polymerase κ (Pol κ), which has been implicated in both nucleotide excision repair and trans-lesion synthesis, required the catalytic activity of METTL3 for immediate localization to ultraviolet-induced DNA damage sites. Importantly, Pol κ overexpression qualitatively suppressed the cyclobutane pyrimidine removal defect associated with METTL3 loss. Thus, we have uncovered a novel function for RNA mA modification in the ultraviolet-induced DNA damage response, and our findings collectively support a model in which mA RNA serves as a beacon for the selective, rapid recruitment of Pol κ to damage sites to facilitate repair and cell survival.
细胞增殖和存活需要遗传信息的忠实维持和传递，而细胞内和外部环境中普遍存在的DNA损伤源会对其构成威胁。一种称为DNA损伤反应的DNA修复系统能够检测并修复受损的DNA，并在修复完成之前阻止细胞分裂。在此，我们报告称，RNA中腺苷（mA）第6位的甲基化在紫外线照射后会在DNA损伤位点迅速（2分钟内）且短暂地被诱导。这种修饰发生在众多聚腺苷酸（poly(A)）转录本上，并受甲基转移酶METTL3（甲基转移酶样3）和去甲基酶FTO（脂肪量和肥胖相关蛋白）调控。在缺乏METTL3催化活性的情况下，细胞对紫外线诱导的环丁烷嘧啶加合物的修复延迟，对紫外线的敏感性升高，这表明mA在紫外线响应性DNA损伤反应中具有重要作用。多种DNA聚合酶参与紫外线反应，其中一些在损伤被核苷酸切除修复途径切除后重新合成DNA，而其他一些则参与跨损伤合成，以允许在S期越过受损损伤进行复制。DNA聚合酶κ（Pol κ）既参与核苷酸切除修复又参与跨损伤合成，它需要METTL3的催化活性才能立即定位于紫外线诱导的DNA损伤位点。重要的是，Pol κ的过表达在质量上抑制了与METTL3缺失相关的环丁烷嘧啶去除缺陷。因此，我们发现了RNA mA修饰在紫外线诱导的DNA损伤反应中的新功能，我们的研究结果共同支持了一个模型，即mA RNA作为一种信号，用于将Pol κ选择性、快速招募到损伤位点，以促进修复和细胞存活。
