Mechanisms of Genome Integrity

项目摘要 我们的染色体不断地受到各种各样的侮辱，造成损害， 必须修复。细胞已经进化出检测和修复DNA断裂链的机制， 从而防止重要遗传信息的丢失。双链DNA断裂（DSB） 是一种会导致特别灾难性后果的损害。如果不加以纠正，争端解决机构可以 会导致染色体重排，这是所有癌症的标志。 同源重组（HR）是细胞可用于修复DSB的保守途径， HR是防止和修复DNA复制过程中出现的损伤所必需的。当 发生DSB时，DNA末端被加工以产生3'单链DNA（ssDNA）突出端。 ssDNA末端然后与基因组中其他地方的同源序列配对， 使用同源DNA作为复制模板来替换DNA。最后，复制 中间体被分解，再生断裂DNA的连续性。HR要求 负责感知损伤的复杂蛋白质库的协调作用， 募集必需因子，加工修复受损的DNA。后果 对HR的干扰是毁灭性的例如，在RAD51重组酶中的突变是 小鼠胚胎致死，人类RAD51的突变与乳腺癌有关。在 此外，BRCA2的缺陷至少占所有乳腺癌的5%，并且还赋予了遗传学上的缺陷。 易患卵巢癌BRCA2被认为有助于调节HR，而这种功能的丧失 调节可能是这种基因与遗传性癌症有关的原因。新的发现将 有必要充分理解这些结果的机制基础。 我们的研究项目专注于了解蛋白质如何感知和响应 然后修复受损的DNA，以防止可能导致 癌为了帮助解决这些问题，我们开发了独特的技术， 使用光学显微镜直接观察数百个单独的分子， 真实的实时监测DNA修复和DNA复制的空间和时间进程 在单分子水平上使用这种方法，我们试图定义基本机制， 我们的细胞用来复制和修复DNA，长期目标是了解如何 这些过程中的错误可导致染色体重排。

PROJECT SUMMARY Our chromosomes are constantly bombarded with a variety of insults, resulting in damage that must be repaired. Cells have evolved mechanisms to detect and repair broken strands of DNA, thereby preventing loss of important genetic information. Double‐stranded DNA breaks (DSBs) are a type of damage that lead to particularly disastrous outcomes. If not corrected, DSBs can cause gross chromosomal rearrangements, which are the hallmark of all forms of cancer. Homologous recombination (HR) is a conserved pathway that cells can use to repair DSBs, and HR is necessary to prevent and repair the damage that arises during DNA replication. When a DSB occurs, the DNA ends are processed to generate 3' single‐strand DNA (ssDNA) overhangs. The ssDNA ends then pair with homologous sequence elsewhere in the genome, and the missing DNA is replaced using the homologous DNA as a template for replication. Finally, the replicated intermediate is resolved, regenerating the continuity of the broken DNA. HR requires the coordinated action of a complex repertoire of proteins, which are responsible for sensing damage, recruiting essential factors, and processing and repairing the damaged DNA. The consequences of disrupting HR are devastating. For example, mutations in the RAD51 recombinase are embryonic lethal in mice, and mutations in human RAD51 are linked to breast cancers. In addition, defects in BRCA2 account for at least 5% of all breast cancers and also confer a genetic predisposition to ovarian cancer. BRCA2 is thought to help regulate HR, and loss of this regulation may be the reason why this gene is linked to hereditary cancers. New discoveries will be necessary to fully understand the mechanistic basis for these outcomes. Our research program is focused on understanding how proteins sense and respond to damaged DNA and they then repair the damaged DNA to prevent mutations that can lead to cancer. To help address these problems we have developed unique technologies that allow us to directly visualize hundreds of individual molecules using optical microscopy, which enables us to monitor the spatial and temporal progression of DNA repair and DNA replication in real‐time at the single‐molecule level. Using this approach, we seek to define the fundamental mechanisms that our cells use to replicate and repair DNA, with the long‐term goal of understanding how errors during these processes can lead to chromosomal rearrangements.