The Systematic Identification and Analysis of Replication Origins in Drosophila

描述：DNA复制是一个重要的细胞周期过程，需要复制染色体的每一个细胞分裂。很少有人知道复制是如何与其他核过程，如转录和染色质修饰协调。尽管最近的基因组研究已经证明了DNA复制时间和转录活性之间的相关性，基因组中活跃转录的区域在早期被复制，但驱动这种相关性的潜在机制仍然不清楚。只有通过系统地表征多细胞类型中后生动物基因组的复制动态，我们才能理解这些过程协调以维持基因组稳定性的机制。 我们将使用高密度基因组平铺路径阵列，充分表征果蝇复制程序在多个细胞系和组织。具体而言，我们将确定果蝇基因组中所有独特序列的复制时间，识别和定位所有复制的功能起点，并确定复制前复合物（preRC，复制起始所需的必需多蛋白复合物）组装的所有位点。preRC组装位点的高分辨率映射将使我们能够应用计算方法（包括比较基因组学）来识别指导和调节preRC功能的潜在序列基序。最后，我们还将描述多线染色体在完全分化的果蝇组织中的差异复制，以确定扩增或复制不足的基因组区域。多线染色体的差异复制提供了一个独特的机会，了解发育线索和染色体域如何影响复制程序。 在增殖细胞中，基因组的复制是一个关键的细胞周期事件，不仅基因组必须精确复制，而且必须精确复制一次。起源选择和激活的调节对于维持基因组的稳定性是必不可少的。不能完全复制基因组或选择序列的不适当的过度复制可能导致肿瘤发生。

DESCRIPTION: DNA replication is an essential cell cycle process required to duplicate the chromosomes each and every cell division. Very little is known about how replication is coordinated with other nuclear processes such as transcription and chromatin modification. Although recent genomic studies have demonstrated a correlation between time of DNA replication and transcriptional activity, with actively transcribed regions of the genome being replicated early, the underlying mechanism driving this correlation remains unclear. Only by systematically characterizing the replication dynamics of a metazoan genome in multiple cell types will we be in a position to understand the mechanisms by which these processes are coordinated to maintain genomic stability. We will use high-density genomic tiling-path arrays to characterize fully the Drosophila replication program in multiple cell lines and tissues. Specifically, we will determine the time of replication for all unique sequences in Drosophila genome, identify and map all functional origins of replication, and identify all sites of prereplicative complex (preRC, an essential multi-protein complex required for replication initiation) assembly. The high-resolution mapping of sites of preRC assembly will enable us to apply computational approaches (including comparative genomics) to identify potential sequence motifs that direct and regulate preRC function. Finally, we will also characterize the differential replication of polytene chromosomes in fully differentiated Drosophila tissues to identify genomic regions that are amplified or underreplicated. The differential replication of polytene chromosomes provides a unique opportunity to understand how developmental cues and chromosomal domains influence the replication program. In proliferating cells, duplication of the genome is a critical cell-cycle event, not only must the genome be copied accurately; it must also be copied exactly once. The regulation of origin selection and activation is essential to maintain genomic stability. The failure to completely replicate the genome or the inappropriate over-replication of select sequences may lead to tumorigenesis.