Regulation of the ATR Checkpoint Kinase by DNA Damage

描述(由申请人提供)：如何在细胞分裂和发育过程中保持基因组的稳定性是细胞与发育生物学的一个基本问题，对包括癌症在内的人类疾病具有重要意义。为了维持稳定的基因组，细胞依赖于几个细胞过程的协同作用，包括忠实的DNA复制、高效的DNA修复和协调的细胞周期进程。DNA损伤信号通路，也被称为DNA损伤检查点，是这些过程的中心指挥者。共济失调-毛细血管扩张症突变和RAD3相关(ATR)检查点激酶是检查点通路的主要调节者。作为广泛DNA损伤和基因组不稳定的主要细胞传感器，ATR在保护基因组，特别是在DNA复制过程中发挥着关键作用。ATR信号受损会增加基因组的不稳定性，导致癌症的发生和发展。此外，ATR被辐射和许多化疗药物激活，ATR反应缺陷使癌细胞对外在和内在DNA损伤高度敏感。鉴于ATR在DNA损伤反应和癌症治疗中的关键作用，了解ATR激活和发挥作用的分子机制具有重要意义。更好地了解ATR的调节和功能对于开发针对癌细胞基因组不稳定性的新的癌症治疗方法至关重要。我们在这个方案中的主要目标是了解在DNA损伤反应中ATR是如何转化为一个完全活性的激酶的。此外，我们将研究ATR-Chk1信号通路如何在DNA损伤反应的早期阶段被激活，以及如何在反应的后期被失活。我们的研究将结合生化、细胞生物学和蛋白质组学方法。特别是，我们将分析ATR及其调节因子和效应器在DNA损伤后是如何修改的，以及这些修改是如何调节它们的功能的。我们还将系统地开发一个体外生化检测系统来概括DNA损伤对ATR的激活作用。这些研究将使我们能够清楚地定义导致ATR激活的关键分子事件，以及通过ATR-Chk1途径协调信号的关键事件。这些研究可能极大地推进目前的ATR激活模型，为未来揭示ATR的全部生物学功能及其在靶向癌症治疗中的意义提供分子基础。

DESCRIPTION (provided by applicant): How genomic stability is maintained during cell divisions and development is a fundamental question for Cell and Developmental Biology with a strong implication in human diseases including cancer. To maintain a stable genome, cells rely on the concerted action of several cellular processes, including faithful DNA replication, efficient DNA repair, and coordinated cell cycle progression. The DNA damage-signaling pathway, also known as the DNA damage checkpoint, is the central conductor of these processes. The ataxia-telangiectasia mutated and rad3-related (ATR) checkpoint kinase is a master regulator of the checkpoint pathway. As the main cellular sensor of a broad spectrum of DNA damage and genomic instability, ATR plays a key role in protecting the genome, particularly during DNA replication. Compromised ATR signaling increases genomic instability, contributing to the development and progression of cancer. Furthermore, ATR is activated by radiation and many chemotherapeutic drugs, and defective ATR response renders cancer cells highly sensitive to extrinsic and intrinsic DNA damage. Given the pivotal role of ATR in DNA damage response and cancer therapy, it is of great importance to understand the molecular mechanisms by which ATR is activated and by which it functions. A better understanding of the regulation and function of ATR will be critical for the development of new cancer therapies to target the genomic instability in cancer cells. Our main goal in this proposal is to understand how ATR is transformed into a fully active kinase during DNA damage response. Furthermore, we will investigate how the ATR- Chk1 signaling pathway is activated during the early stage of DNA damage response, and how it is deactivated at the late stage of the response. Our studies will combine biochemical, cell biological, and proteomic approaches. In particular, we will analyze how ATR and its regulators and effectors are modified after DNA damage, and how these modifications regulate their functions. We will also systematically develop an in vitro biochemical assay system to recapitulate the activation of ATR by DNA damage. These studies will allow us to clearly define the key molecular events that lead to ATR activation, as well as the key events that orchestrate the signaling through the ATR-Chk1 pathway. These studies may significantly advance the current model of ATR activation, providing the molecular basis for future studies to reveal the full biological functions of ATR and its implications in targeted cancer therapy.