Molecular Mechanisms of Genetic Recombination in Mammals

哺乳动物基因重组的分子机制

• 批准号: 8269772
• 负责人: Galina Petukhova
• 金额: $ 28.32万
• 依托单位: HENRY M. JACKSON FDN FOR THE ADV MIL/MED
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-01 至 2014-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8269772
• 关键词: Address; Aneuploidy; Cell Nucleus; Cells; Chromatin; Chromosome Segregation; Chromosomes; Complex; Congenital Abnormality; Cues; DNA; DNA Double Strand Break; Ensure; Epigenetic Process; Evaluation; Event; Frequencies; Gametogenesis; Genetic Recombination; Genome; Germ Cells; Goals; Homologous Gene; Human; Individual; Infertility; Location; Mammals; Maps; Measures; Meiosis; Meiotic Recombination; Molecular; Mus; Mutation; Nuclear Matrix; Nuclear Structure; Outcome; Pathway interactions; Preventive; Probability; Process; Regulation; Rest; Role; Site; Spatial Distribution; Staging; Therapeutic; Work; base; chromatin immunoprecipitation; comparative; daughter cell; driving force; genome-wide; mammalian genome; mouse genome; repaired; segregation

PROJECT SUMMARY/ABSTRACT Aneuploidy - the wrong number of chromosomes in an individual - is the leading cause of birth defects in humans. It results from errors in the segregation of homologous chromosomes (homologs) during gametogenesis. The proper segregation is ensured by meiotic recombination. It begins with the introduction of DNA double stranded breaks (DSBs) followed by their repair using the intact DNA of a homologous chromosome as a template. This leads to a temporal association of the homologs stabilized by crossing-overs (COs). Such an arrangement into pairs ensures orderly segregation of the homologous chromosomes to the opposite poles of dividing nuclei so that each gamete receives one homolog of each pair. The homologs that fail to pair segregate randomly, and have a 50% chance to go into the same daughter cell. Along with the lack of COs, positional effects of CO placement also contribute to aneuploidy. Spatial distribution of recombination events is controlled at different levels and defining the mechanisms of this regulation is necessary to understand why some of the events escape this control. Our long-term goal is to elucidate the mechanisms behind faulty meiotic recombination resulting in aneuploidy in mammals. In this study we will take a genome-wide approach to define the mechanisms of CO placement in the mouse. (i) By cytological evaluation of the mouse meiotic chromosomes we will determine whether placement of meiotic DSBs is random or displays interference, i.e. the formation of one DSB suppresses the formation of a second one in adjacent regions. This will help to clarify the mechanisms involved in imposition of CO interference. (ii) Using chromatin immunoprecipitation followed by direct high-throughput sequencing we will map the regions of mouse genome where meiotic DSBs tend to occur (hotspots of meiotic DSBs). Recombination is not evenly distributed throughout the genome and defining the particular features associated with recombination hotspots will provide the cues to the mechanism behind their formation. (iii) We will map the hotspots of meiotic COs using the similar approach. Comparative analysis of these two maps will help to elucidate the pathways leading to CO formation, and the mechanisms involved in CO/NCO designation. Overall, the results from our studies will illuminate several important aspects of the mechanisms involved in CO placement, and will also create new avenues for future research in delineating the mechanism of meiotic recombination control. Mutations that reduce or abolish recombination are invariably associated with meiotic arrest or chromosome segregation errors leading to infertility or aneuploidy. Understanding the forces driving recombination is necessary before preventive measures and therapeutic approaches can be developed.

项目概要/摘要 非整倍体（个体染色体数量错误）是出生的主要原因 人类的缺陷。它是由同源染色体（同系物）分离错误引起的 在配子发生期间。减数分裂重组确保正确的分离。它开始于 引入 DNA 双链断裂 (DSB)，然后使用完整 DNA 进行修复 以同源染色体为模板。这导致同源物的时间关联 通过交叉（CO）稳定。这种成对的排列确保了有序的隔离 将同源染色体连接到分裂核的相反两极，以便每个配子接收 每对一个同系物。未能配对的同系物随机分离，并且有 50% 有机会进入同一个子细胞。随着 CO 的缺乏，CO 的位置​​效应 放置也有助于非整倍性。重组事件的空间分布控制在 为了理解为什么有些 的事件逃脱了这种控制。我们的长期目标是阐明故障背后的机制 减数分裂重组导致哺乳动物非整倍体。在这项研究中，我们将采用全基因组 方法来定义 CO 在小鼠中的放置机制。 (i) 通过细胞学评估 小鼠减数分裂染色体，我们将确定减数分裂 DSB 的放置是随机的还是 显示出干扰，即一个 DSB 的形成抑制了第二个 DSB 的形成 邻近地区。这将有助于阐明施加 CO 干扰的机制。 (ii) 使用染色质免疫沉淀，然后进行直接高通量测序，我们将绘制图谱 小鼠基因组中减数分裂 DSB 容易发生的区域（减数分裂 DSB 的热点）。 重组并非均匀分布在整个基因组中并定义了特定特征 与重组热点相关的基因将为它们背后的机制提供线索 形成。 (iii) 我们将使用类似的方法绘制减数分裂 CO 的热点图。比较 对这两张图的分析将有助于阐明导致 CO 形成的途径，以及 CO/NCO 指定涉及的机制。总的来说，我们的研究结果将阐明 CO 安置所涉及机制的几个重要方面，也将创造新的 描绘减数分裂重组控制机制的未来研究途径。突变 减少或消除重组总是与减数分裂停滞或染色体有关 分离错误导致不孕或非整倍体。了解驱动重组的力量 在制定预防措施和治疗方法之前，这是必要的。