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突触如何在减数分裂过程中促进适当的染色体分离。减数分裂期间的染色体错误分离与人类不育直接相关，也是已知的智力迟钝和发育障碍的主要遗传原因。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的复杂途径。在前期I，同源染色体配对，然后突触。突触是通过在同源染色体之间形成的称为突触复合体的蛋白质结构的组装而发生的。突触复合体的成功组装是减数分裂过程中染色体分离的关键先决条件。然而，关于这些结构组装动力学的许多基本问题仍未得到解答。我们的目标是确定突触复合体的组装过程如何促进其双重功能：1)维持同源物之间的紧密联系；2)促进交叉及其调控。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来确定出芽酵母中突触复合物组装的动力学，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？突触可以从起始位点延伸多远？在过去，这些问题的答案一直没有得到研究，因为在大多数生物体中，在一个高度紧密的细胞核中，多个移动的染色体在很长一段时间内从大量的位点进行突触。为了降低问题的复杂性，我们建议引入zip3突变，1)将突触染色体的数量限制在1个，2)将染色体上的多个位点的成核改变为一个，或最多两个位点。在Synapsis之后，将对Zip1蛋白进行成像，Zip1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，但不能成像突触的形成。我们的第二个目标是描述成核过程。为了完成这项任务，我们将起始复合物的组分偶联到雌激素受体的配体结合域，使融合蛋白在引入雌激素之前保持非活性。然后，我们可以研究起始复合物的各种已知组分的引入和时间如何影响突触的进展。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的交叉控制，我们将评估突触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。)