Kinetics of Chromosome Synapsis During Meiosis

减数分裂过程中染色体突触的动力学

• 批准号: 8082173
• 负责人: JENNIFER C FUNG
• 金额: $ 28.58万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-15 至 2016-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8082173
• 关键词: 3-Dimensional; Affect; Aneuploidy; Cell Nucleus; Cells; Centromere; Chromosome Pairing; Chromosome Segregation; Chromosomes; Chromosomes, Human, Pair 16; Chromosomes, Human, Pair 2; Complex; Coupled; Development; Developmental Disabilities; Diagnostic tests; Ensure; Estradiol; Estrogen Receptors; Estrogens; Event; Excision; Fertility; Gametogenesis; Genetic; Genetic Crossing Over; Genetic Recombination; Genomics; Germ Cells; Goals; Homologous Gene; Human; Image; Image Analysis; Individual; Infertility; Investigation; Kinetics; Lead; Life; Ligand Binding Domain; Measurement; Medical; Meiosis; Meiotic Prophase I; Mental Retardation; Microscopic; Microscopy; Motion; Mutation; Operative Surgical Procedures; Optic Chiasm; Organism; Pathway interactions; Play; Process; Prophase; Proteins; Regulation; Relative (related person); Research; Resolution; Role; Saccharomycetales; Signal Transduction; Site; Structure; Synapses; Synaptonemal Complex; Testing; Time; Work; base; cell type; chromosome movement; fluorescence imaging; genome-wide; in vivo; innovation; novel strategies; polymerization; prevent; receptor binding

DESCRIPTION (provided by applicant): The long-term goal of this research is to determine how chromosome synapsis functions to promote proper chromosome segregation during meiosis. Chromosome missegregation during meiosis is directly tied to human infertility and is also the leading known genetic cause for mental retardation and developmental disabilities. Elucidating the basic mechanisms underlying proper chromosome segregation during meiosis will enable greater understanding of the intricate pathways that contribute to normal gametogenesis and fertility. During prophase I, homologous chromosomes pair and then synapse. Synapsis occurs via the assembly of a proteinaceous structure known as the synaptonemal complex that forms between homologous chromosomes. Successful assembly of the synaptonemal complex is a key prerequisite to proper chromosome segregation during meiosis. However, many basic questions about the kinetics of assembly of these structures remain unanswered. Our objective for this proposal is to determine how the process of synaptonemal complex assembly contributes towards its dual function of 1) maintaining a tight association between homologs and 2) promoting crossing over and its regulation. Our first aim uses fast, live, 3-D fluorescence imaging and quantitative image analysis to determine the kinetics of synaptonemal complex assembly in budding yeast to answer several important questions. What is the rate of synapsis polymerization? Is it bidirectional or unidirectional? How far can synapsis extend from one initiation site? In the past, the answers of these questions have eluded investigation, due to the fact that in most organisms, multiple moving chromosomes are synapsing from a large number of sites, over a long time frame, in a highly compacted nucleus. To reduce the complexity of the problem, we propose to introduce a zip3 mutation that 1) limits the number of synapsing chromosomes to as low as one and 2) changes nucleation from multiple sites to one, or at most two sites, along the chromosome. Synapsis will be followed by imaging the Zip1 protein that has been previously coupled to GFP and used successfully to image the motion of fully synapsed chromosomes but not synapsis formation. Our second aim will be to characterize the process of nucleation. To accomplish this task, we will couple components of the initiation complex to a ligand binding domain of the estrogen receptor that keeps the fused protein inactive until introduction of estrogen. We then can investigate how the introduction and timing of various known components of the initiation complex influences the progression of synapsis. For our last aim, we will determine whether changes in synapsis nucleation and polymerization rates affect crossing over and its regulation. Using a genome-wide approach developed in my lab for looking at crossover control in a single cell that has undergone meiosis, we will assess how particular changes in synaptonemal complex assembly and nucleation can affect crossover distribution and thus chromosome segregation.) PUBLIC HEALTH RELEVANCE: Chromosome missegregation during meiosis is directly tied to human infertility and is also the leading known genetic cause for mental retardation and developmental disabilities. This work investigates the mechanisms in place to ensure faithful chromosome segregation by elucidating how the assembly of the synaptonemal complex contributes to this process. Such research may lead to new ideas for treatment of infertility or to development of diagnostic tests to detect potential problems of chromosome segregation early on before expensive medical and surgical treatments are attempted.

描述（由申请人提供）：这项研究的长期目标是确定染色体突触的功能如何促进减数分裂过程中适当的染色体分离。减数分裂过程中的染色体错误进行分离直接与人类不育症有关，也是智力低下和发育障碍的已知遗传原因。阐明减数分裂过程中适当的染色体分离的基本机制将使人们对有助于正常配子发生和生育能力的复杂途径有更多了解。 在预言I期间，同源染色体对，然后突触。突触是通过组装的蛋白质结构的组装而来的，称为同源染色体之间形成的突发型复合物。成功组装突发型复合体是减数分裂过程中适当的染色体分离的关键先决条件。但是，有关这些结构组装动力学的许多基本问题仍未得到解答。我们对该提案的目标是确定突触复合组装的过程如何有助于其双重功能1）维持同源物之间的紧密关联和2）促进过境及其调节。我们的第一个目标使用快速，实时的3-D荧光成像和定量图像分析来确定在萌芽酵母中的突触复合体组装的动力学，以回答几个重要问题。突触聚合的速率是多少？是双向的还是单向的？突触可以延伸到一个起始站点多远？过去，由于在大多数生物体中，多个移动的染色体在高度紧凑的核中长期以来从大量地点突触，因此这些问题的答案已经避免了研究。为了降低问题的复杂性，我们建议引入一个Zip3突变，即1）将突触的染色体数量限制为低至1和2）将成核从多个位点变为一个或大多数两个位点，沿染色体。突触之后，将成像Zip1蛋白，该Zip1蛋白先前已与GFP耦合，并成功用于成像完全突触的染色体的运动，而不是突触形成。我们的第二个目标是表征成核过程。为了完成这项任务，我们将将起始复合物的组成部分与雌激素受体的配体结合结构域进行，该雌激素受体保持融合蛋白不活跃，直到引入雌激素。然后，我们可以研究起始复合物的各种已知组成部分的引入和时机如何影响突触的发展。为了我们的最后一个目标，我们将确定突触成核的变化和聚合速率是否会影响越过及其调节。使用在我的实验室中开发的全基因组方法，以查看经历了减数分裂的单个细胞中的交叉控制，我们将评估突触复合物组装和成核的特定变化如何影响交叉分布，从而影响染色体分离。） 公共卫生相关性：减数分裂过程中的染色体错误分类直接与人类不孕症有关，也是智力低下和发育障碍的已知遗传原因。这项工作通过阐明突发型复合体的组装有助于这一过程来确保忠实的染色体隔离的机制。此类研究可能会导致对不孕症治疗或开发诊断测试的新想法，以在尝试尝试昂贵的医疗和手术治疗之前，早期检测染色体隔离的潜在问题。