Mechanisms of Genome Integrity

基因组完整性的机制

• 批准号: 9923696
• 负责人: Eric C Greene
• 金额: $ 51.06万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-01 至 2021-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9923696
• 关键词: Address; BRCA2 gene; Cells; Chromosomal Rearrangement; Chromosomes; Complex; DNA; DNA Damage; DNA Double Strand Break; DNA Repair; DNA Sequence; DNA biosynthesis; Defect; Embryo; Event; Genes; Genetic Predisposition to Disease; Genetic Recombination; Genome; Goals; Hereditary Malignant Neoplasm; Human; Individual; Lead; Link; Malignant Neoplasms; Malignant neoplasm of ovary; Microscopy; Monitor; Mus; Mutation; Natural regeneration; Optics; Outcome; Pathway interactions; Process; Proteins; Rad51 recombinase; Regulation; Research; Sequence Homologs; Single-Stranded DNA; Source; Technology; Time; ds-DNA; genetic information; genome integrity; homologous recombination; malignant breast neoplasm; prevent; programs; public health relevance; recruit; repaired; single molecule

 DESCRIPTION (provided by applicant): Our chromosomes are continually bombarded with a variety of insults, resulting in damage that must be repaired. By necessity, 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 led to particularly disastrous outcomes. If not corrected, DSBs can lead to gross chromosomal rearrangements, which are the hallmark of all forms of cancer. Surprisingly, DNA replication is the primary source of DSBs. Homologous recombination (HR) is a highly 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 sequence is replaced using the homologous DNA as a template for replication. Finally, the replicated intermediate is resolved, regenerating the continuity of the broken DNA. While seemingly simple, 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. Major new discoveries will be necessary to fully understand the mechanistic basis for these outcomes. Our overall research program is focused on understanding how (i) proteins sense and respond to damaged DNA, (ii) how DNA damage is repaired, (iii) how DNA replication can lead to damage, and (iv) how replication and recombination are linked. 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.

 描述（由申请人提供）：我们的染色体不断受到各种侮辱的轰炸，导致必须修复的损伤。出于必要，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）是一种导致特别灾难性后果的损伤。如果不纠正，DSB可能导致严重的染色体重排，这是所有形式癌症的标志。令人惊讶的是，DNA复制是DSB的主要来源。 同源重组（HR）是一个高度保守的途径，细胞可以用来修复DSB，HR是必要的，以防止和修复DNA复制过程中出现的损伤。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，并且使用同源DNA作为复制模板来替换缺失的DNA序列。最后，复制的中间体被分解，再生出断裂DNA的连续性。虽然看似简单，但HR需要一系列复杂蛋白质的协调作用，这些蛋白质负责感知损伤，招募必需因子，以及处理和修复受损的DNA。扰乱HR的后果是毁灭性的。例如，Rad51重组酶的突变在小鼠中是胚胎致死的，而人类Rad51的突变与乳腺癌有关。此外，BRCA2缺陷至少占所有乳腺癌的5%，并且还赋予卵巢癌的遗传易感性。BRCA2被认为有助于调节HR，这种调节的丧失可能是该基因与遗传性癌症相关的原因。要充分理解这些结果的机制基础，就必须有重大的新发现。 我们的整体研究计划侧重于了解（i）蛋白质如何感知和响应受损的DNA，（ii）DNA损伤如何修复，（iii）DNA复制如何导致损伤，以及（iv）复制和重组如何联系。为了帮助解决这些问题，我们开发了独特的技术，使我们能够使用光学显微镜直接可视化数百个单独的分子，这使我们能够在单分子水平上实时监测DNA修复和DNA复制的时空进展。使用这种方法，我们试图定义我们的细胞用于复制和修复DNA的基本机制，长期目标是了解这些过程中的错误如何导致染色体重排。