Roles for Mismatch Repair Proteins in Maintaining Genome Stability

描述（由申请人提供）：多种内源性和外源性试剂可损伤DNA，导致诱变和基因组不稳定。这些反过来又会导致人类疾病，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，并参与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MutS同系物（MSH）蛋白复合物识别DNA损伤，之后激活适当的DNA修复途径。我们研究的长期目标是了解DNA损伤的识别如何与不同的DNA修复途径相结合，以及MSH蛋白参与这一过程的方式。我们特别感兴趣的是MSH 2-MSH 3复合物，它识别插入/缺失环以及遗传重组的中间体。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。我们提出，MSH 2-MSH 3识别和结合到特定的DNA底物信号不同的修复机制。我们的研究计划将采用各种生物化学和遗传学方法来了解MSH-DNA相互作用触发适当DNA损伤反应的机制。在我们的第一个目标中，我们将表征MSH 2-MSH 3与不同DNA底物的相互作用，并研究MSH 2-MSH 3动力学如何受到这种结合的影响。这些研究将在理解MSH 2-MSH 3如何发现并结合其各种底物以启动修复方面具有广泛的相关性。在我们的第二个目标中，我们将重点关注3'非同源尾去除的分子细节和MSH 2-MSH 3所起的作用。这个知之甚少的过程对于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MSH 2-MSH 3-DNA识别的下游事件。我们将鉴定和表征在不同DNA损伤条件下与MSH 2-MSH 3相互作用的其他蛋白质。总之，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，这对于维持细胞的遗传完整性和整个生物体的健康至关重要。

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.