Roles for Mismatch Repair Proteins in Maintaining Genome Stability

描述(由申请人提供)：各种各样的内源性和外源性因素可以破坏DNA，导致突变和基因组不稳定。这些反过来会导致人类疾病，特别是癌症。错配修复系统(MMR)是识别和纠正DNA损伤的多种DNA修复途径之一，参与了许多维持基因组完整性的过程。在每个过程中，关键的第一步是识别MutS Homolog(MSH)蛋白复合体对DNA的损伤，然后激活适当的DNA修复途径。我们研究的长期目标是了解识别DNA损伤是如何与不同的DNA修复途径相耦合的，以及MSH蛋白参与这一过程的方式。我们对MSH2-MSH3复合体特别感兴趣，它识别插入/缺失环以及基因重组的中间产物。这些不同的底物通过不同的途径分解，需要独特的下游因素。我们认为，MSH2-MSH3识别和结合到特定的DNA底物上发出不同的修复机制。我们的研究计划将使用各种生化和遗传学方法来了解MSHDNA相互作用触发适当的DNA损伤反应的机制(S)。在我们的第一个目标中，我们将表征MSH2-MSH3与不同DNA底物的相互作用，并研究这种结合如何影响MSH2-MSH3的动力学。这些研究将对理解MSH2-MSH3如何找到并结合其各种底物以启动修复具有广泛的相关性。在我们的第二个目标中，我们将重点关注3‘非同源尾巴去除的分子细节以及MSH2-MSH3所起的作用。这一鲜为人知的过程对酵母和哺乳动物系统中的单链退火和其他双链DNA断裂修复途径至关重要。我们的第三个目标将集中在MSH2-MSH3-DNA识别的下游事件上。我们将识别和表征在不同的DNA损伤条件下与MSH2-MSH3相互作用的其他蛋白质。综上所述，这项研究将为不同DNA修复途径的调节和协调提供重要的见解，这对维持细胞的遗传完整性和整个生物体的健康至关重要。与公共卫生相关：DNA的突变和损伤可能导致多种人类癌症。多条DNA修复途径可以识别和纠正各种DNA损伤。我们有兴趣了解错配修复途径如何将DNA损伤识别与DNA修复协调起来，以消除对人类健康有害的突变损伤。

DESCRIPTION (provided by applicant): A wide variety of endogenous and exogenous agents can damage the DNA, leading to mutagenesis and genome instability. These, in turn, can lead to human disease, particularly cancer. The mismatch repair system (MMR) is one of multiple DNA repair pathways that recognize and correct DNA damage and is involved in a number of processes to maintain genome integrity. In each process, the crucial first step is recognition of DNA damage by MutS Homolog (MSH) protein complexes, after which the appropriate DNA repair pathway is activated. The long term goal of our research is to understand how recognition of DNA damage is coupled to distinct DNA repair pathways and the way in which MSH proteins are involved in this process. We are particularly interested in the MSH2-MSH3 complex, which recognizes insertion/deletion loops as well as intermediates of genetic recombination. These different substrates are resolved through distinct pathways that require unique downstream factors. We propose that MSH2-MSH3 recognition and binding to specific DNA substrates signals different repair mechanisms. Our research plan will employ a variety of biochemical and genetic approaches to understand the mechanism(s) by which a MSH-DNA interaction triggers the appropriate DNA damage response. In our first Aim, we will characterize MSH2-MSH3 interactions with distinct DNA substrates and examine how MSH2-MSH3 dynamics are affected by that binding. These studies will have broad relevance in understanding how MSH2-MSH3 finds and binds its various substrates to initiate repair. In our second Aim, we will focus on the molecular details of 3' non-homologous tail removal and the role played by MSH2-MSH3. This poorly understood process is critical for single-strand annealing and other double-strand DNA break repair pathways in both yeast and mammalian systems. Our third Aim will focus on the events downstream of MSH2-MSH3-DNA recognition. We will identify and characterize additional proteins that interact with MSH2-MSH3 under differing DNA damaging conditions. In summary, this research will provide important insight into the regulation and coordination of distinct DNA repair pathways, which is critical for maintaining the genetic integrity of a cell and the health of an entire organism. PUBLIC HEALTH RELEVANCE: Mutations and damage to DNA can lead to a wide variety of human cancers. Multiple DNA repair pathways recognize and correct a variety of DNA lesions. We are interested in understanding how the mismatch repair pathway coordinates DNA damage recognition with DNA repair to eliminate mutagenic lesions that would be detrimental to human health.