Genome instability induced by homologous recombination

项目摘要 拟议研究的总体目标是确定途径及其机制， 同源重组导致体细胞中基因组的不稳定性， DNA序列使用芽殖酵母酿酒酵母作为模式生物，我们将定义 由单个Rad 51-ssDNA诱导的多重入侵诱导重排的突变特征 同时与不同染色体上的重复DNA序列配对或在一个染色体上的位置配对。 单染色体目的是建立适用的新机制和范例 关于基因组稳定性和基因组维持的核心问题。我们将建立新的突变 由同源重组引起的签名，这将有助于定义这种机制的基础 在人类中发现的特征，包括癌症基因组。此外，我们的工作将有助于了解 在个体发育过程中形成基因组的主要过程的机制， 进化，包括非等位基因同源重组，插入，突变阵雨（kataegis），双 微小的染色体形成和染色体不稳定综合征，如染色体断裂。 具体目标是： 1.确定多重入侵诱导的基因组重排的遗传后果。多重 入侵诱导的重排与单链DNA和二级DNA双链有关， 搁浅断裂。我们将确定这些中间体的致突变潜力， DNA双链断裂产生二次重排波（Aim 1A）、插入波（Aim 1B） 聚集点突变（Aim 1C）和染色体外环形成（Aim 1D）。 2.识别影响多重入侵的途径和全基因组同源性搜索。使用 通过对多重入侵介导的重排的遗传终点分析，我们开发了一个 质量控制，防止多重入侵。在目标2A中，我们将定义类型和位置的影响 DSB的。在目标2B中，我们将使用物理测定来直接量化单次和多次侵袭以及 DNA产物来测试我们的模型多重侵入是全基因组同源性的灵敏读数 搜索结合我们的物理分析，我们在Aim 2C中有独特的机会来确定 全局核结构和过程对体内全基因组同源性搜索效率的影响。

Project Summary The general goal of the proposed research is to define the pathways and their mechanisms by which homologous recombination contributes to genome instability in somatic cells through events involving repeated DNA sequences. Using the budding yeast Saccharomyces cerevisiae as a model organism we will define the mutational signatures of multi-invasion-induced rearrangements, which are induced by a single Rad51-ssDNA filament simultaneously pairing with repeated DNA sequences on different chromosomes or locations on a single chromosome. The aims are designed to establish novel mechanisms and paradigms that are applicable to central questions concerning genomic stability and genome maintenance. We will establish novel mutational signatures caused by homologous recombination that will help to define the mechanism underlying such signatures found in humans, including cancer genomes. Moreover, our work will contribute to understanding the mechanisms underlying major processes that shape genomes during ontogenic development and evolution, including non-allelic homologous recombination, insertions, mutation showers (kataegis), double minute chromosome formation, and chromosome instability syndromes such as chromothripsis. The Specific Aims are: 1. Determine the genetic consequences of multi-invasion-induced genome rearrangements. Multi- invasion-induced rearrangements are associated with single-stranded DNA and secondary DNA double- stranded breaks. We will define the mutagenic potential of these intermediates induced by the initial single DNA double-strand break to generate secondary waves of rearrangements (Aim 1A), insertions (Aim 1B), clustered point mutations (Aim 1C), and extrachromosomal circle formation (Aim 1D). 2. Identify pathways that affect multi-invasions and the genome-wide search for homology. Using genetic endpoint analysis of multi-invasion-mediated rearrangements, we developed a mechanistic model of quality control that guards against multi-invasions. In Aim 2A, we will define the impact of the type and position of the DSB. In Aim 2B, we will use physical assays to directly quantify single- and multi-invasions as well as the DNA product to test our model. Multi-invasions are sensitive readouts of the genome-wide homology search. Paired with our physical assays, we have the unique opportunity in Aim 2C to determine to effect of global nuclear architecture and processes on the efficiency of the genome-wide homology search in vivo.