Regulation of DNA replication by histone modifications

描述（由申请人提供）：拟议研究的广泛、长期目标是在分子水平上确定体内DNA复制的机制。基因组的忠实复制是细胞周期中的重要步骤。这一过程中的任何干扰都可能导致细胞死亡、基因组不稳定或细胞生长失控。因此，研究DNA复制的机制不仅有助于基础生物学的广泛领域，而且有助于理解人类疾病（如癌症和发育障碍）的分子基础。DNA复制需要高度协调的复制因子在染色质背景下的复制起点的募集，以及DNA聚合酶通过染色质模板的进展。因此，预计复制起点周围的组蛋白修饰模式强烈影响DNA复制。很可能在每个DNA复制周期之前，在复制起点周围建立了适当的组蛋白修饰模式。然而，由于技术限制，在细胞周期进程中组蛋白修饰模式如何在DNA复制起点周围改变以及组蛋白修饰的特定模式如何影响DNA复制尚未确定。我们最近开发了一种新的系统，以微克数量纯化自主复制的染色质环。结合超灵敏的质谱仪，我们的系统为我们提供了一个独特的机会，以公正的方式在细胞周期进程中围绕DNA复制起点识别组蛋白修饰。我们将使用我们的系统来验证我们的假设，即组蛋白修饰在细胞周期进程中处于动态调节下，并在DNA复制中发挥关键作用。

DESCRIPTION (provided by applicant): The broad, long term goal of the proposed study is to determine, at the molecular level, the mechanisms by which DNA replication occurs in vivo. Faithful duplication of the genome is an essential step in the cell cycle. Any disturbance in this process can lead to cell death, genomic instability, or unregulated cell growth. Therefore, studying the mechanisms of DNA replication will contribute not only to broad areas of basic biology, but also to understanding the molecular basis for human diseases, such as cancer and developmental disorders. DNA replication requires highly coordinated recruitment of replication factors to replication origins in a chromatin context, as well as progression of DNA polymerases through a chromatin template. It is therefore expected that histone modification patterns around replication origins strongly affect DNA replication. It is highly likely that proper histone modification patterns are established around replication origins before each DNA replication cycle. However, how histone modification patterns change around DNA replication origins during cell cycle progression and how specific patterns of histone modification affect DNA replication have not been determined, due to technical limitations. We have recently developed a new system to purify an autonomously replicating chromatin circle in microgram quantities. Combined with an ultra-sensitive mass spectrometry instrument, our system gives us a unique opportunity to identify histone modifications in an unbiased fashion around DNA replication origins during cell cycle progression. We will use our system to test our hypothesis that histone modifications are under dynamic regulation during cell cycle progression and play critical roles in DNA replication.