Chromatin regulated DNA replication

描述(申请人提供)：真核基因组的繁殖依赖于从许多来源开始的DNA复制。起始活性需要结合和激活复制前复合体(Pre-RC)。然而，在多细胞真核生物中，还不知道染色体上的某些区域是如何被选择用于前RC结合和激活的；DNA共识尚未出现。此外，作为起源的基因组位点以及它们在S阶段启动的时间在发育过程中可能会发生变化，但目前尚不清楚是什么决定了这种发育特异性。我们使用了一个基于果蝇蛋壳(绒毛膜)基因发育扩增的模型系统来研究起源、鉴定和基因组复制的调节。我们以前的结果表明，核小体乙酰化调节卵巢中绒毛膜和其他来源的发育特异性。我们建议通过使用遗传学和分子方法研究核小体修饰影响起源活性的机制来扩展这项工作。这一建议的一个重要方面是，它利用在果蝇中的方法来解决染色质在起源活动的发育特异性中的作用。我们的长期目标是描述起源染色质修饰的完整谱系，揭示染色质改变起源活性的机制，并发现这些修饰是如何针对发育中不同细胞类型的特定起源的。这项研究应该会对发育过程中基因组复制的表观遗传控制产生重要的新见解。 层次描述：每次细胞分裂都必须复制一份完整而准确的DNA。为了完成这项巨大的任务，细胞开始从无数的“起点”复制。基因组中的某些位置是如何被选择作为起源的，目前还不清楚。这项建议研究了染色体结构如何调节不同细胞中DNA复制的起点。这一结果将使人们更深入地了解这一过程中的缺陷是如何导致人类癌症的，从而导致更好的诊断和治疗。

DESCRIPTION (provided by applicant): The propagation of the eukaryotic genome depends upon the initiation of DNA replication from numerous origins. Origin activity requires the binding and activation of a pre-Replicative Complex (pre-RC). In multi-cellular eukaryotes, however, it is not known how certain regions on chromosomes are selected for pre-RC binding and activation; a DNA consensus has yet to emerge. Moreover, the genomic sites that act as origins, and the time that they initiate during S phase, can change during development, but it is not known what determines this developmental specificity. We have employed a model system based on developmental amplification of Drosophila eggshell (chorion) genes to investigate origin identity and the regulation of genome duplication. Our previous results indicated that nucleosome acetylation regulates the developmental specificity of chorion and other origins in the ovary. We propose to extend this work by investigating the mechanism by which nucleosome modifications influence the activity of origins using genetic and molecular methods. An important aspect of this proposal is that it takes advantage of methods in Drosophila to address the role of chromatin in developmental specificity of origin activity. Our long term goals are to describe the full repertoire of chromatin modifications at origins, to reveal the mechanism by which chromatin alters origin activity, and to discover how these modifications are targeted to specific origins in different cell types in development. This investigation should lead to important new insights into the epigenetic control of genome duplication during development. Lay description: A complete and accurate copy of DNA must be made each cell division. To accomplish this large task, the cell starts copying from numerous "origins". How certain sites in the genome are chosen to be origins is not understood. This proposal investigates how the structure of chromosomes regulates where DNA replication starts in different cells. The results will provide a deeper understanding for how defects in this process contribute to human cancers, leading to better diagnosis and therapies.