Recombination pathway and partner choice during C. elegans meiosis

线虫减数分裂过程中的重组途径和伴侣选择

• 批准号: 8488057
• 负责人: Diana Elizabeth Libuda
• 金额: $ 9.81万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8488057
• 关键词: Address; Biological Assay; Caenorhabditis elegans; Cell division; Cell physiology; Cells; Chromosomal Breaks; Chromosome Segregation; Chromosome Structures; Chromosomes; Congenital Abnormality; Cytological Techniques; DNA; DNA Damage; DNA Double Strand Break; DNA Repair; Data; Development; Diploidy; Double Strand Break Repair; Ensure; Event; Fertility; Foundations; Genetic; Genetic Recombination; Genetic Techniques; Genetic Variation; Genome; Genomics; Germ Cells; Goals; Gonadal structure; Haploidy; Health; Homologous Gene; Human; Image; Life; Malignant Neoplasms; Meiosis; Meiotic Recombination; Monitor; Optic Chiasm; Organism; Other Genetics; Outcome; Pathway interactions; Phase; Positioning Attribute; Process; Prophase; Protein Isoforms; Proteins; Publishing; Reagent; Research; Role; Sister Chromatid; Site; Staging; System; Testing; Time; Work; egg; new technology; novel; preference; premature; prevent; programs; public health relevance; recombinase; recombinational repair; repaired; restoration; segregation; sperm cell

DESCRIPTION (provided by applicant): Recombination between chromosomes is required to generate genetic variation, maintain genome integrity through the repair of double strand DNA breaks (DSBs), and ensure proper chromosome segregation during meiosis, the specialized cell division program by which diploid organisms generate haploid gametes such as sperm and eggs. Perturbations in recombination events can compromise these basic cellular functions, ultimately leading to cancer, fertility problems, or birth defects. Meiotic recombination is initiaed by DSBs, which are repaired using meiosis-specific mechanisms that favor utilization of the homologous chromosome (instead of the sister chromatid) as the recombination partner and that promote a crossover (rather than noncrossover) outcome of the DSB repair (DSBR) process. Crossover recombination between homologous chromosomes is required to create temporary physical connections that promote proper chromosome segregation during meiosis. In order to promote these recombination pathway and partner preferences required for generating crossovers between homologous chromosomes, germ cells engage a specialized DSBR program at the onset of meiotic prophase. During late meiotic prophase, meiotic cells undergo a second switch in the DSBR requirements, which is proposed to revert to utilization of repair preferences typical of mitotically dividing cells (e.g. favoring the sister chromatid as the repair partner). This proposed switch would enable repair of any remaining DSBs prior to the meiotic divisions, thereby preserving genomic integrity. Utilizing the C. elegans experimental system, the proposed studies will address how different recombination pathways and partners are employed during meiosis to both promote crossover formation between homologs and repair any remaining DSBs prior to the meiotic divisions. To assess the temporal and mechanistic features of these pathway and partner choices, I will expand the scope of our recently published assay system by developing an assay to detect and distinguish the different repair products of DSBs induced at a defined site. With this assay, I will directly test for the hypothesized switch in partner preference during meiotic prophase progression and determine the effect of chromosomal position on specific repair outcomes and partner choices. Also, utilizing a variety of genetic and cytological techniques, I will assess the roles of known meiotic proteins in promoting specific meiotic repair outcomes. Further, I will utilize two new reagents I generated to assess dynamics of the early stages of meiotic DSBR in live worms, establish the roles of meiotic chromosome structures in regulating DSB formation and repair, and determine a relationship between specific repair partner choices and classes of early DSBR stage dynamics. Overall, these studies will reveal how recombination pathway and partner preferences ensure that chromosomes form the connections necessary for chromosome segregation and repair DSBs for maintaining genomic integrity.

描述（由申请人提供）：染色体之间的重组需要产生遗传变异，通过修复双链DNA断裂（DSBs）保持基因组完整性，并确保在减数分裂过程中适当的染色体分离，减数分裂是二倍体生物产生单倍体配子（如精子和卵子）的特殊细胞分裂程序。重组事件中的扰动会损害这些基本的细胞功能，最终导致癌症、生育问题或出生缺陷。减数分裂重组是由DSB启动的，它们使用减数分裂特异性机制进行修复，这种机制有利于利用同源染色体（而不是姐妹染色单体）作为重组伙伴，并促进DSB修复（DSBR）过程的交叉（而不是非交叉）结果。同源染色体之间的交叉重组需要在减数分裂过程中创造暂时的物理连接，以促进适当的染色体分离。为了促进这些重组途径和同源染色体间交叉所需的伴侣偏好，生殖细胞在减数分裂前期开始时参与了一个专门的DSBR程序。在减数分裂后期前期，减数分裂细胞经历DSBR需求的第二次开关，这被认为是恢复到利用有丝分裂细胞典型的修复偏好（例如，倾向于姐妹染色单体作为染色体）