Regulation of Homologous Recombination in Human Cells

人类细胞同源重组的调控

• 批准号: 8268383
• 负责人: Nathan A. Ellis
• 金额: $ 32.58万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8268383
• 关键词: ATP phosphohydrolase; Affect; Affinity; Amino Acids; Binding; Binding Proteins; Binding Sites; Biochemical; Bloom Syndrome; Catalysis; Cells; Characteristics; Chromosomal Instability; DNA; DNA Damage; DNA Repair; DNA biosynthesis; Data; Defect; Development; Double Strand Break Repair; Exhibits; Failure; Genes; Genetic Recombination; Genomic Instability; Genomics; Human; In Vitro; Joints; Laboratories; Lead; Lysine; Malignant Neoplasms; Mediating; Modeling; Molecular; Molecular Cytogenetics; Mutate; Normal Cell; Pathway interactions; Phenotype; Process; Recombinant Proteins; Recruitment Activity; Regulation; Research; Role; Site; Speed; Testing; Ubiquitin; Work; base; cancer cell; cancer therapy; design; helicase; homologous recombination; in vivo; insight; mutant; overexpression; prevent; recombinase; recombinational repair; repaired; research study; response; therapeutic target; ubiquitin-protein ligase

DESCRIPTION (provided by applicant): Homologous recombination (HR) is an essential mechanism that maintains genomic integrity in cells by repairing double-strand breaks and repairing damaged replication forks. The RAD51 recombinase catalyzes the central step in the HR pathway, forming joint molecules through homology-dependent strand invasion. The BLM helicase, which is the gene mutated in Bloom's syndrome (BS), regulates RAD51. BLM can promote RAD51 function, for example by generating substrate for RAD51 binding, or it can inhibit RAD51 function by unwinding the products of RAD51 catalysis, which prevents the accumulation of toxic recombination intermediates. Thus, through its regulation of RAD51, BLM has both pro- and anti-recombinogenic functions in HR. We have shown that BLM is modified by small ubiquitin-related modifiers (SUMOs) and that BLM SUMOylation regulates BLM's functions at stalled replication forks, stimulating HR repair. In addition, RAD51 is SUMO-binding, and BLM SUMOylation stimulates BLM's interaction with RAD51 in vitro. Our findings support a model in which BLM SUMOylation controls a switch between BLM's anti- recombinogenic and pro-recombinogenic functions. To test this hypothesis, we have four specific aims: (1) characterization of the role of BLM SUMOylation in stabilization of replication forks; (2) characterization of the role of RAD51 SUMO binding in replication fork stability and HR repair; (3) analysis of the effects of BLM SUMOylation on BLM's biochemical activities and RAD51 function; and (4) analysis of the effects of BLM SUMOylation and RAD51 SUMO binding in genomic integrity. Our studies will elucidate the molecular mechanisms that regulate HR at damaged replication forks, providing insights into the dynamic functions of BLM and RAD51 in HR repair and leading to a deeper understanding of how these functions are regulated by the SUMO pathway. Because HR repair mechanisms are often dysregulated in cancer cells, our work will lead to a better understanding of genomic instability in cancer and will facilitate the exploitation of this instability in cancer treatments.

描述（由申请人提供）：同源重组（HR）是通过修复双链断裂和修复受损的复制叉来维持细胞中基因组完整性的重要机制。 RAD51 重组酶催化 HR 途径的核心步骤，通过同源依赖性链入侵形成联合分子。 BLM 解旋酶是布卢姆综合征 (BS) 中突变的基因，它调节 RAD51。 BLM 可以促进 RAD51 功能，例如通过生成 RAD51 结合的底物，或者它可以通过解开 RAD51 催化产物来抑制 RAD51 功能，从而防止有毒重组中间体的积累。因此，通过对 RAD51 的调节，BLM 在 HR 中具有促重组和抗重组功能。我们已经证明，BLM 可以通过小的泛素相关修饰物 (SUMO) 进行修饰，并且 BLM SUMO 化可以调节 BLM 在停滞复制叉上的功能，从而刺激 HR 修复。此外，RAD51 具有 SUMO 结合作用，BLM SUMO 化可在体外刺激 BLM 与 RAD51 的相互作用。我们的研究结果支持这样一个模型：BLM SUMOylation 控制 BLM 的抗重组功能和促重组功能之间的转换。为了检验这一假设，我们有四个具体目标：（1）表征 BLM SUMOylation 在稳定复制叉中的作用； (2)表征RAD51 SUMO结合在复制叉稳定性和HR修复中的作用； (3)分析BLM SUMO化对BLM生化活性和RAD51功能的影响； (4)分析BLM SUMO化和RAD51 SUMO结合对基因组完整性的影响。我们的研究将阐明调节受损复制叉处 HR 的分子机制，深入了解 BLM 和 RAD51 在 HR 修复中的动态功能，并更深入地了解 SUMO 途径如何调节这些功能。由于癌细胞中的 HR 修复机制通常失调，因此我们的工作将有助于更好地了解癌症中的基因组不稳定性，并有助于在癌症治疗中利用这种不稳定性。