ATM activation by DNA single-strand breaks

项目总结/摘要 作为最常见的DNA损伤形式，DNA单链断裂（SSB）来源于 环境毒素和化疗药物以及内源性资源，如中间体 氧化应激中的DNA修复产物，并与癌症和 神经退行性疾病尽管人们普遍认为ATM对于修复和维护是必不可少的， DNA双链断裂（DSB）的信号，它仍然是未知的SSBs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维持基因组稳定性。我们 利用生化、结构和功能分析的大量初步数据表明，ATM- 介导的DNA损伤反应（DDR）途径被非洲爪蟾中定义的SSB结构激活 鸡蛋提取物，这种SSB诱导的ATM激活早于ATR激活。值得注意的是， 机制研究表明，一个关键的上游调节因子与SSB诱导的ATM有关， activation.因此，我们将在基因组中剖析SSB诱导ATM激活的分子机制 通过两个特定目的实现完整性：（1）确定ATM介导的DDR通路是否以及如何被激活 通过在爪蟾卵提取物中确定的SSB结构和用纯化蛋白质重建系统，和 (2)确定该上游调节剂如何促进SSB诱导的ATM的机制 activation. NIH R21项目的预期结果将提供ATM被激活的直接证据 通过定义的SSB结构以及SSB诱导的ATM激活如何调节和协调。所以我们 研究将通过调节不同的细胞因子， SSB诱导的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.