The Systematic Identification and Analysis of Replication Origins in Drosophila

描述：DNA 复制是细胞周期中必不可少的过程，每次细胞分裂都需要复制染色体。关于复制如何与转录和染色质修饰等其他核过程相协调，人们知之甚少。尽管最近的基因组研究已经证明 DNA 复制时间和转录活性之间存在相关性，并且基因组的活跃转录区域被早期复制，但驱动这种相关性的潜在机制仍不清楚。只有通过系统地表征多种细胞类型中后生动物基因组的复制动态，我们才能了解协调这些过程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来全面表征果蝇在多个细胞系和组织中的复制程序。具体来说，我们将确定果蝇基因组中所有独特序列的复制时间，识别和绘制所有复制功能起点，并识别复制前复合物（preRC，复制启动所需的重要多蛋白复合物）组装的所有位点。 preRC 组装位点的高分辨率图谱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，我们还将表征完全分化的果蝇组织中多线染色体的差异复制，以识别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来了解发育线索和染色体结构域如何影响复制程序。 在增殖细胞中，基因组复制是一个关键的细胞周期事件，不仅基因组必须被准确复制，而且还必须被复制。它也必须被复制一次。起源选择和激活的调节对于维持基因组稳定性至关重要。未能完全复制基因组或选择序列的不适当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.