ATM activation by DNA single-strand breaks

项目摘要/摘要 作为最常见的DNA损伤形式，DNA单链断裂(SSB)源于 环境毒素和化疗药物以及中间体等内源性资源 DNA修复产物在氧化应激中的作用，并被认为与癌症和 神经退行性疾病。鉴于人们普遍认为自动取款机对维修和 DNA双链断裂(DSB)的信号转导，目前尚不清楚SSB是否以及如何触发ATM 激活，以及SSB诱导的ATM激活如何在分子水平上保持基因组的稳定性。我们的 使用生化、结构和功能分析的大量初步数据表明，ATM- 非洲爪哇介导的DNA损伤反应(DDR)途径是由确定的SSB结构激活的 这种SSB诱导的ATM激活早于ATR激活。值得注意的是，进一步 机制研究表明，SSB诱导的ATM与一个关键的上游调节因子有关 激活。因此，我们将剖析SSB诱导基因组atm激活的分子机制。 通过两个特定目标实现完整性：(1)确定ATM介导的DDR通路是否以及如何被激活 通过在非洲爪哇卵子提取和纯化蛋白重组系统中确定SSB结构，以及 (2)确定上游调节因子在单边带诱导ATM中的作用机制 激活。NIH R21项目的预期结果将提供ATM被激活的直接证据 通过定义SSB结构以及如何调节和协调SSB诱导的ATM激活。因此，我们的 研究将为潜在的癌症治疗提供新的途径，通过调节不同的 SSB诱导ATM激活在基因组完整性和癌症病因学中的调节机制。

Project Summary/Abstract As the most common form of DNA lesions, DNA single-strand breaks (SSBs) are derived from environmental toxins and chemotherapy drugs as well as endogenous resources such as intermediate DNA repair products in oxidative stress, and have been implicated in association with cancer and neurodegenerative disorders. Whereas it is widely accepted that ATM is essential for the repair and signaling of DNA double-strand breaks (DSBs), it remains unknown whether and how SSBs trigger ATM activation, and how SSB-induced ATM activation maintains genome stability at the molecular level. Our substantial preliminary data using biochemical, structure and function analyses suggest that ATM- mediated DNA damage response (DDR) pathway is activated by the defined SSB structure in Xenopus egg extracts and that such SSB-induced ATM activation is earlier than ATR activation. Notably, further mechanistic studies suggest that a critical upstream regulator is implicated in the SSB-induced ATM activation. Thus, we will dissect the molecular mechanisms of SSB-induced ATM activation in genome integrity via two Specific Aims: (1) determine whether and how ATM-mediated DDR pathway is activated by defined SSB structures in Xenopus egg extracts and reconstitution system with purified proteins, and (2) determine the mechanism of how this upstream regulator contributes to the SSB-induced ATM activation. Anticipated results from this NIH R21 project will provide direct evidence that ATM is activated by defined SSB structures and how SSB-induced ATM activation is regulated and coordinated. Thus, our studies will provide novel avenues for potential cancer therapies through the modulation of distinct regulatory mechanisms of SSB-induced ATM activation in genome integrity and cancer etiology.