Eukaryotic Chromosome Replication

描述(由申请人提供)： 项目摘要DNA复制对生命的重要性毋庸置疑，因此，细胞已经进化出监测复制保真度和协调复制完成与其他细胞周期事件的机制。这个项目的目标是了解细胞如何编排它们染色体的复制，以及DNA复制缺陷可能如何导致人类最近发现的一些疾病。真核生物中的染色体复制是一个涉及每条染色体多个起始点(起始点)调控的过程。起源在时间上和效率上都有差异--并非所有起源都在S阶段同时激发--也不是所有起源都必然在每个细胞周期中激发。此外，单元格APPEA用于维护在特殊情况下使用的原点(休眠原点)的备份集，并且这些原点在其基本控制属性上可能不同。因此，了解原产地使用是如何受到监管的，对于了解基因组完整性是如何维持的至关重要。最近描述的与复制缺陷有关的三种遗传疾病强调了这一概念：1)Meier-Gorlin综合征及其对起源许可至关重要的基因的点突变；2)与小鼠乳腺癌和人类生长异常有关的复制解旋酶编码部分的基因点突变；以及3)人类节段性三重现象，其中心拷贝倒置，可以用复制叉错误来解释。酵母是研究DNA复制的理想模式生物，因为它的小染色体，明确的起源序列，易于改变染色体结构，以及特殊的遗传和基因组分析系统。该项目将综合应用分子、遗传学和基因组学方法，以发现酵母中起源效率和时间的调节因子，探索/调查有序复制如何有助于基因组稳定性？利用与人类疾病相关的基因在酵母同源基因中的点突变，以了解复制缺陷的下游后果，因为它们与人类健康和疾病有关，并确定缺陷的遗传和化学抑制因素？确定DNA复制错误是否导致特定类别的反向扩增，可能导致癌症进展和先天性拷贝数变异。这个项目将解决有关染色体复制控制生物学的悬而未决的问题：为什么起源在不同的时间启动复制，不同时间类别的起源有什么区别，低效起源的分子基础是什么，以及复制分叉过程中的哪些缺陷使染色体座位易于反向扩增？此外，这项工作将使人们深入了解由于染色体复制错误而导致的人类疾病，并可能导致诊断或治疗方面的进步。

DESCRIPTION (provided by applicant): PROJECT SUMMARY DNA replication is undeniably important for life and as a consequence, cells have evolved mechanisms to monitor replication fidelity and to coordinate completion of replication with other cell cycle events. The goal of this project is to understand how cells choreograph the duplication of their chromosomes, and how defects in DNA replication may contribute to some recently discovered disorders in humans. Chromosome replication in eukaryotes is a process that involves the regulation of multiple initiation sites (origins) per chromosome. Origins show variation in timing-not all origins fire at the same time in S phase-and in efficiency-not all origins necessarily firing in every cell cycle. In addition, cells appea to maintain a backup set of origins (dormant origins) for use under special circumstances and these origins may differ in their basic control properties. Understanding how origin use is regulated is therefore critical for understanding how genome integrity is maintained. This notion is underscored by three recently described genetic disorders with links to replication defects: 1) Meier-Gorlin Syndrome with its point mutations in genes essential for origin licensing; 2) a point mutation in a gene encoding part of the replicative helicase that is associated with breast cancer in mice and growth abnormalities in humans; and 3) human segmental triplications with an inverted central copy that can be explained by a replication fork error. Yeast is an ideal model organism for studying DNA replication because of its small chromosomes, well defined origin sequences, ease of altering chromosome structure, and exceptional systems for genetic and genomic analysis. This project will apply a combination of molecular, genetic and genomics approaches to: ¿ uncover modulators of origin efficiency and timing in yeast, to explore/investigate how orderly replication contributes to genome stability ¿ use point mutations in the yeast orthologs of genes involved in human disorders to understand the downstream consequences of defects in replication as they relate to human health and disease, and to identify genetic and chemical suppressors of the defects ¿ determine whether DNA replication errors are responsible for a particular class of inverted amplicons that can contribute to cancer progression and congenital copy number variants. This project will address outstanding questions regarding the biology of chromosome replication control: why do origins initiate replication at different times, what distinguishes origins in different temporal categories, what i the molecular basis for inefficient origins, and what defects in replication fork progression predispose chromosomal loci to inverted amplification? In addition, this work will give insight int human disorders resulting from errors in chromosome replication and could lead to diagnostic or therapeutic advances.