Molecular Mechanisms of Genetic Recombination in Mammals

哺乳动物基因重组的分子机制

• 批准号: 7795181
• 负责人: Galina Petukhova
• 金额: $ 28.61万
• 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/7795181
• 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; Future; 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; Research; Rest; Role; Site; Spatial Distribution; Staging; Therapeutic; Work; base; chromatin immunoprecipitation; comparative; daughter cell; driving force; genome-wide; mammalian genome; mouse genome; public health relevance; repaired; segregation

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: The goal of this study is to elucidate the mechanisms involved in genetic recombination. Mutations that reduce or abolish recombination are invariably associated with infertility or aneuploidy, and understanding the forces driving recombination is necessary before preventive measures and therapeutic approaches can be developed.

描述（由申请人提供）：非整倍性-个体中染色体数目错误-是人类出生缺陷的主要原因。它是由配子发生过程中同源染色体（同系物）分离错误引起的。通过减数分裂重组确保适当的分离。它首先引入DNA双链断裂（DSB），然后使用同源染色体的完整DNA作为模板进行修复。这导致通过交换（CO）稳定的同系物的时间关联。这种成对的排列方式确保了同源染色体有序地分离到分裂核的两极，这样每个配子就能得到每对染色体的一个同源体。未能配对的同源物随机分离，并有50%的机会进入同一个子细胞。沿着CO的缺乏，CO放置的位置效应也有助于非整倍体。重组事件的空间分布在不同的水平上受到控制，并且定义这种调节的机制对于理解为什么一些事件逃脱这种控制是必要的。我们的长期目标是阐明导致哺乳动物非整倍体的错误减数分裂重组背后的机制。在这项研究中，我们将采取全基因组的方法来定义CO在小鼠中的放置机制。(i)通过对小鼠减数分裂染色体的细胞学评价，我们将确定减数分裂DSB的放置是随机的还是显示干扰，即一个DSB的形成抑制了相邻区域中第二个DSB的形成。这将有助于澄清CO干扰的实施机制。(ii)使用染色质免疫沉淀，然后直接高通量测序，我们将绘制小鼠基因组中减数分裂DSB倾向于发生的区域（减数分裂DSB的热点）。重组在整个基因组中并不是均匀分布的，定义与重组热点相关的特定特征将为它们形成背后的机制提供线索。(iii)我们将使用类似的方法绘制减数分裂CO的热点。这两个地图的比较分析将有助于阐明导致CO形成的途径，和参与CO/NCO指定的机制。总的来说，我们的研究结果将阐明参与CO放置机制的几个重要方面，也将为未来研究描绘减数分裂重组控制机制创造新的途径。减少或消除重组的突变总是与减数分裂停滞或染色体分离错误相关，导致不育或非整倍性。在制定预防措施和治疗方法之前，必须了解驱动重组的力量。 公共卫生相关性：本研究的目的是阐明基因重组的机制。减少或消除重组的突变总是与不育或非整倍体有关，在开发预防措施和治疗方法之前，了解驱动重组的力量是必要的。