DNA损伤修复蛋白OGG1对肺部炎症的调控及其表观遗传机制

Our preliminary observations found that mice lung inflammation induced by ozone exposure was accompanied by 7, 8-dihydro-8-oxoguanine (8-oxoG) highly expressed in the airway epithelium, the oxidative DNA damage marker that could be recognized and repaired by specific DNA glycosylase OGG1 initiated base excision repair (BER) pathway. OGG1 enriched in the intron of a specific inflammatory gene and bound to DNA: RNA hybrid produced during transcription, thus promoting nascent RNA production. These findings suggest that oxidative stress induced inflammatory response could be mediated by DNA damage repair through epigenetic pathways. We hypothesize that in lung inflammation, airway epithelial cells are the first to response to oxidative stress, and 8-oxoG produced in inflammatory gene regulatory regions could recruit OGG1, thereby regulating the process of transcription, which lay the foundation to the initiation of lung inflammation. This project is intended to study: (1) the effects of OGG1 deletion or inhibition on oxidative stress induced lung inflammation; (2) screening for OGG1-regulated cytokine and chemokine expression profiles in lung inflammation; (3) the mechanism of transcriptional regulation by OGG1 binding to DNA: RNA hybrids. This project will innovate the ideas of oxidative DNA damage has epigenetic characteristics, and seek the possibility of targeting oxidative DNA damage as a new strategy for the treatment of lung inflammation.

申请者初步观察到臭氧应激导致的小鼠肺部炎症伴有DNA氧化损伤标志物8-羟基鸟嘌呤（8-oxoG）在气道上皮高表达，而特异性识别8-oxoG的DNA损伤修复蛋白OGG1富集于特定炎症基因的内含子区，与转录过程中产生的DNA:RNA杂合子相结合后可促进新生RNA生成。这些发现提示DNA损伤修复可通过表观遗传途径介导氧化应激相关的炎症过程。我们推测：在肺组织炎症中气道上皮细胞首先应答氧化性刺激，产生的8-oxoG可募集OGG1到达炎症相关基因非编码区，从而改变基因转录的模式，构成肺部炎症的启动基础。本项目拟研究：①OGG1缺失或抑制后对氧化应激肺部炎症的影响；②筛选肺部炎症中受OGG1调控的细胞因子和趋化因子表达谱；③OGG1结合DNA:RNA杂合体调控基因转录的机制解析。本项目将创新DNA氧化损伤具有表观遗传特征的理论研究思路，寻求以氧化性DNA损伤作为治疗肺部炎症新靶点的可能性。

项目研究观察到臭氧应激导致的小鼠肺部炎症模型中，特异性识别并修复氧化性DNA损伤标志物8-羟基鸟嘌呤（8-oxoG）的DNA损伤修复酶8-羟基鸟嘌呤核糖水解酶1（OGG1）能够调节炎症性细胞因子的表达，其分子机制与OGG1结合DNA:RNA杂交链，从而调节新生RNA生成相关。通过检测小鼠肺组织匀浆和肺泡灌洗液，项目研究筛选出OGG1调节的炎症性细胞因子还涉及到细胞外基质蛋白稳态调节和组织重塑，因此项目进行过程深入探讨了氧化应激活化OGG1蛋白功能后，从而调节促纤维化基因和细胞外基质蛋白基因的表达，而这些基因在上皮-间质转化（EMT）过程中具有重要的调节作用。研究结果表明，OGG1作为先驱因子，有助于气道上皮细胞内的转录重编程，使用OGG1小分子抑制剂TH5487减轻了TGFβ1诱导的纤维化基因表达和肺组织重塑。因此，OGG1特异性识别基因组上8-oxoG底物是调节气道上皮细胞基因转录的中心枢纽，从而维持肺组织损伤修复平衡。项目资助发表SCI论文7篇，待发表论文2篇。培养硕士研究生2名，全部取得硕士学位。项目投入经费24万元，各项支出基本与预算相符。