Chromatin Regulation of Double-Strand Break Repair

DNA修复和DNA损伤检查点对于肿瘤抑制是重要的，并且是至关重要的。 肿瘤对放射和化学治疗剂的抗性的决定因素。DNA双链断裂 由遗传毒性化学物质和电离辐射产生，并在DNA合成过程中自发产生。 复制的DSB通过非同源末端连接（NHEJ）和同源重组修复 （人力资源）。DSB发生在染色质的背景下，染色质改变在DSB的发生中起重要作用。 招募DNA修复和检查点蛋白到损伤位点。拟议的研究旨在 确定染色质修饰和重塑在蛋白质募集到DSB中的作用，以及在 酵母酿酒酵母中DSB修复结果的调节。我们的核心假设是， DSB修复效率和结果通过修复蛋白的整合作用来调节， 检查点蛋白和染色质动力学。我们将通过追求三个具体目标来检验这一假设 集中于（1）染色质变化在修复和检查点蛋白向DSB募集中的作用;（2） 定义HR期间DSB位点和供体基因座处的染色质变化;以及（3）确定染色质如何 调节DSB修复。与组蛋白H2 A的磷酸化一样，我们发现核小体移位 在修复蛋白及时补充到DSB中起作用。这些和其他染色质的作用 DSB蛋白质募集的改变，DSB修复的调节，以及检查点的激活将是 研究了这些研究将阐明染色质改变如何调节细胞对DSB的反应， 从而确定DSB损伤的遗传后果。建议的研究是相关的，因为 染色质修饰、DSB修复和检查点应答从酵母到人类都是保守的。 这些研究意义重大，因为它们将揭示DSB修复中的新调控机制，从而确定 癌症放射治疗和化学治疗的新靶点。

DMA repair and DNA damage checkpoints are important for tumor suppression, and are critical determinants of tumor resistance to radiation and chemotherapeutics. DNA double-strand breaks (DSBs) are produced by genotoxic chemicals and ionizing radiation, and arise spontaneously during DNA replication. DSBs are repaired by non-homologous end-joining (NHEJ) and homologous recombination (HR). DSBs occur in the context of chromatin, and chromatin alterations play important roles in the recruitment of DNA repair and checkpoint proteins to damage sites. The proposed studies are designed to determine the roles of chromatin modification and remodeling in protein recruitment to DSBs, and in the regulation of DSB repair outcome in the yeast Saccharomyces cerevisiae. Our central hypothesis is that DSB repair efficiency and outcome are regulated through the integrated actions of repair proteins, checkpoint proteins, and chromatin dynamics. We will test this hypothesis by pursuing three Specific Aims focused on (1) the roles of chromatin changes in recruitment of repair and checkpoint proteins to DSBs; (2) defining chromatin changes at a DSB site and a donor locus during HR; and (3) determining how chromatin regulates DSB repair. As with phosphorylation of histone H2A, we found that nucleosome displacement plays a role in the timely recruitment of repair proteins to DSBs. The roles of these and other chromatin alterations in protein recruitment to DSBs, regulation of DSB repair, and checkpoint activation will be investigated. These studies will clarify how chromatin alterations regulate cellular responses to DSBs and thereby determine the genetic consequences of DSB damage. The proposed studies are relevant because chromatin modifications, DSB repair, and checkpoint responses are conserved from yeast to man. The studies are significant because they will reveal new regulatory mechanisms in DSB repair, and thus identify new targets to exploit in cancer radio- and chemotherapy.