O-GlcNAc糖基化可逆修饰调控非同源末端连接介导的DNA双链断裂修复的机制研究

OGT介导的O-GlcNAc糖基化修饰和OGA介导的去修饰参与调控DNA损伤应答。但O-GlcNAc糖基化可逆修饰在DNA双链断裂（DSB）修复中的调控机制尚不清楚。我们发现OGA晚于OGT被募集至DNA损伤位点参与DNA双链断裂修复，OGA的HAT结构域对募集起重要作用；亲和纯化结合质谱鉴定发现三个非同源末端连接（NHEJ）修复因子为OGA结合蛋白，DNA损伤诱导其糖基化修饰，OGA介导去糖基化修饰。因此，我们推测O-GlcNAc糖基化可逆修饰通过调控NHEJ修复途径在DSB修复中发挥重要作用。为此，本项目拟研究OGA如何识别DNA损伤位点的O-GlcNAc糖基化信号和调控NHEJ介导的DSB修复及确定OGA抑制剂抑瘤效果，为阐明O-GlcNAc糖基化可逆修饰在DSB修复的作用及调控机制提供理论基础，为肿瘤治疗提供新思路。

OGT mediated O-GlcNAcylation and OGA mediated deglycosylation are involved in regulating DNA damage repair response. However, the detailed molecular mechanism by which reversible O-GlcNAcylation modification regulates DNA double-strand break (DSB) repair remains elusive. We found that OGA’s recruitment at DNA lesions was slower than that of OGT to repair DNA double-strand break and pseudo HAT domain of OGA was responsible for OGA’s recruitment; We found three NHEJ factors were as binding partners of OGA by affinity purification and Mass spectrometry; DNA damage induced their O-GlcNAcylation modifications which could be erased by OGA. Based on our previous study, we hypothesize that the reversible O-GlcNAcylation plays a key role in DSB repair by regulating NHEJ pathway. Here, we plan to examine how the OGA recognizes the O-GlcNAc signal at DNA lesions and regulates the NHEJ mediated DSB repair and the antitumor efficiency of OGA inhibitor in vivo. We plan to clarify the molecular mechanism of reversible O-GlcNAcylation in regulating DNA double-strand break repair, which will provide a novel strategy for clinical tumor treatment.