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）：本研究的长期目标是确定染色体联会如何在减数分裂过程中发挥作用以促进正确的染色体分离。减数分裂期间的染色体错误分离与人类不育直接相关，也是导致智力迟钝和发育障碍的主要已知遗传原因。阐明减数分裂过程中染色体分离的基本机制将有助于更好地理解正常配子发生和生育力的复杂途径。 在前期I，同源染色体配对，然后突触。联会通过在同源染色体之间形成的被称为联会复合体的蛋白质结构的组装而发生。联会复合体的成功组装是减数分裂期间染色体正确分离的关键先决条件。然而，这些结构的组装动力学的许多基本问题仍然没有答案。我们的目标是确定联会复合体组装过程如何有助于其双重功能：1）保持同源物之间的紧密联系，2）促进交换及其调节。我们的第一个目标是使用快速，实时，三维荧光成像和定量图像分析，以确定在芽殖酵母联会复合体组装的动力学，以回答几个重要的问题。突触聚合的速率是多少？是双向的还是单向的？突触能从一个起始点延伸多远？在过去，这些问题的答案一直逃避调查，因为在大多数生物体中，多个移动染色体在很长一段时间内从大量位点突触在一个高度致密的细胞核中。为了降低问题的复杂性，我们建议引入一个zip3突变，1）限制突触染色体的数量低至1和2）改变成核从多个网站到一个，或最多两个网站，沿着染色体。突触之后将成像Zip1蛋白，该蛋白先前已与GFP偶联，并成功地用于成像完全突触染色体的运动，但不是突触形成。我们的第二个目标是描述成核过程的特征。为了完成这项任务，我们将偶联起始复合物的成分雌激素受体的配体结合域，保持融合蛋白的活性，直到引入雌激素。然后，我们可以研究如何引入和各种已知的组件的起始复合体的时间影响突触的进展。对于我们的最后一个目标，我们将确定突触成核和聚合速率的变化是否影响交叉及其调节。使用在我的实验室开发的全基因组方法来观察经历减数分裂的单个细胞中的交叉控制，我们将评估联会复合体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：减数分裂期间的染色体错误分离与人类不育直接相关，也是导致智力迟钝和发育障碍的主要已知遗传原因。这项工作调查的机制，以确保忠实的染色体分离，阐明如何组装的联会复合体有助于这一进程。这种研究可能会导致治疗不孕症的新想法，或开发诊断测试，以在尝试昂贵的医疗和手术治疗之前早期检测染色体分离的潜在问题。