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DNA复制在体内发生的机制。基因组的忠实复制对生命至关重要。这一过程中的任何干扰都可能导致基因组不稳定、不受调节的细胞生长或细胞死亡。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，而且有助于了解人类疾病的分子基础，如癌症和发育障碍。DNA复制需要在染色质背景下高度协调地招募复制因子到复制起点。因此，预计在复制起点周围的组蛋白修饰会强烈影响DNA复制。因此，有证据支持组蛋白修饰在复制中的重要作用。然而，组蛋白修饰是如何围绕DNA复制起源进行调节的，以及这些修饰如何影响DNA复制的不同步骤，仍然是一个重要的开放性问题。在目前的资助周期中，我们已经开发出一种非常有效的系统来纯化位于活性复制原点附近的组蛋白。结合超灵敏质谱分析，我们确定了以前未知的组蛋白修饰模式，这些模式特异性地存在于活性复制起源周围。此外，我们已经证明这些修饰在DNA复制和/或细胞对复制应激的反应中起重要作用。在这个资助周期中，我们建议扩展这些发现，以阐明这些新发现的组蛋白修饰如何在分子水平上起作用。

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 essential for life. Any disturbance in this process can lead to genomic instability, unregulated cell growth or cell death. 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. It is therefore expected that histone modifications around replication origins strongly affect DNA replication. Accordingly, there is supporting evidence for significant roles of histone modifications in replication. However, how histone modifications are regulated around DNA replication origins and how these modifications affect different steps of DNA replication still remain as important open questions. In the current funding cycle of this grant, we have developed an extremely efficient system to purify histones that are located near an active replication origin. Combined with ultra-sensitive mass spectrometry analyses, we identified previously unknown patterns of histone modifications that are present specifically around an active replication origin. Furthermore, we have shown that these modifications play important roles in DNA replication and/or cellular responses to replication stress. In this funding cycle, we propose to extend these findings to elucidate how these newly identified histone modifications function at the molecular level. PUBLIC HEALTH RELEVANCE: DNA replication and response to replication stress are conserved essential processes. Any abnormality in these processes can lead to cancer, developmental disorder or cell death. The goal of our work is to understand the molecular mechanisms of DNA replication and replication stress response, which will help understand the molecular basis for these disease states.