Checkpoint Signaling and Repair of UV Damage to Human DNA

这个项目的长期目标是描述通路间的分子机制。 核苷酸切除修复(NER)和DNA损伤检查点之间的相互作用。内尔和他的损失 检查点是细胞对DNA损伤反应的两个主要组成部分，这些损伤是由于形成块状DNA 紫外线照射和各种环境中的遗传毒性化学物质和致癌物引起的损伤。缺陷 在这些途径中，与干皮病等人类易患癌症的死亡直接相关 色素性(XP)和共济失调-毛细血管扩张症(AT)。尽管在理解上做了很大的努力 细胞DNA损伤反应的总体机制、分子细节的关系 这两条路径之间的联系仍然难以捉摸，因为人们对这两种系统进行了大量的研究 分开的。为了更系统、更准确地了解细胞对DNA损伤的反应，实验 并制定了解决以下问题的策略：DNA损伤检查点和 DNA损伤后细胞内的DNA修复是协调的吗？有哪些蛋白质因素参与了 互动？这种相互作用的分子基础是什么？使用一种组合的生化、分子 生物学和结构方法，本项目的目的是(1)确定XPA在NER和ATR调节中的作用 细胞周期依赖性的调节，以检验假设，即XPA是NER的主要靶点 ATR检查点对NER功能的调节；(2)确定ATR-XPA蛋白-蛋白的作用 相互作用对紫外线的DNA损伤反应的影响，并检验这种相互作用是一种 紫外光照射下ATR调控NER核内XPA积累的决定因素；(3)检测 XPA的核转位依赖于ATR检查点信号。我们将检验这一假设 ATR检查点信号是DNA损伤诱导的细胞质到核运输所必需的 以及(4)评估ATR调节的XPA磷酸化在DNA损伤反应中的作用以及 XPA磷酸化对核苷酸切除修复的影响。

The long-term objectives of this project are to delineate the molecular mechanisms of interpathway interactions between nucleotide excision repair (NER) and DMA damage checkpoints. NER and the damage checkpoints are two major components in cellular responses to DNA damage due to formation of bulky lesions induced by UV irradiation and various environmental genotoxic chemicals and carcinogens. Defects in these pathways have been directly correlated to human cancer prone deceases such as xeroderma pigmentosum (XP) and Ataxia-Telangiectasia (AT). Although great efforts have been made in understanding the overall mechanism of cellular DNA damage responses, the molecular details about the relationship between the two pathways remain elusive due to the fact that the two systems have been largely studied separately. To gain a more systematic and precise view of cellular responses to DNA damage, experiments and strategies are developed to address the following questions: How the DNA damage checkpoints and DNA repair are coordinated in cells upon DNA damage? What are the protein factors involved in the interactions? And what is the molecular basis of the interactions? Using a combined biochemical, molecular biology and structural approach, this project aims (1) to define the role XPA in ATR regulation of NER and the cell-cycle dependency of the regulation for testing the hypothesis that XPA is the main target in NER for regulation of NER functions by ATR checkpoint; (2) to determine the effects of ATR-XPA protein-protein interaction on DNA damage responses to UV and to test the underlying hypothesis that the interaction is a determinant for nuclear accumulation of XPA for NER regulated by ATR upon UV irradiation; (3) to examine the dependence of nuclear-translocation of XPA on ATR checkpoint signaling. We will test the hypothesis that ATR checkpoint signaling is required for the DNA damage-induced cytoplasm-to-nuclear trafficking of XPA; and (4) to assess the role of ATR-regulated XPA phosphorylation in DNA damage responses and the effects of XPA phosphorylation on nucleotide excision repair.