Kinetics of Chromosome Synapsis During Meiosis

减数分裂过程中染色体突触的动力学

基本信息

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
项目类别：
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

项目摘要

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发挥作用以促进减数分裂期间适当的染色体分离。减数分裂过程中的染色体错误分离与人类不孕症直接相关，也是导致智力低下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正确分离的基本机制将有助于更好地理解有助于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，然后形成突触。联会是通过同源染色体之间形成的称为联会复合体的蛋白质结构的组装而发生的。联会复合体的成功组装是减数分裂过程中染色体正确分离的关键先决条件。然而，有关这些结构组装动力学的许多基本问题仍未得到解答。我们此提案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）维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、3D 荧光成像和定量图像分析来确定芽殖酵母中联会复合体组装的动力学，从而回答几个重要问题。突触聚合的速率是多少？是双向的还是单向的？突触可以从一个起始位点延伸多远？过去，这些问题的答案一直未能得到研究，因为在大多数生物体中，多个移动染色体在一个高度压缩的细胞核中，在很长一段时间内从大量位点进行突触。为了降低问题的复杂性，我们建议引入一种 zip3 突变，它 1) 将突触染色体的数量限制为低至 1 个，2) 将成核从多个位点更改为染色体上的一个或最多两个位点。突触之后将对 Zip1 蛋白进行成像，该蛋白先前已与 GFP 偶联，并成功用于对完全突触染色体的运动进行成像，但未对突触形成进行成像。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，我们将起始复合物的成分与雌激素受体的配体结合结构域偶联，使融合蛋白保持非活性，直到引入雌激素。然后我们可以研究起始复合体的各种已知成分的引入和时间安排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会影响交叉及其调节。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。）公共健康相关性：减数分裂过程中的染色体错误分离与人类不孕症直接相关，也是导致智力低下和发育障碍的主要已知遗传原因。这项工作通过阐明联会复合体的组装如何促进这一过程来研究确保染色体忠实分离的机制。此类研究可能会带来治疗不孕症的新思路，或开发诊断测试，以便在尝试昂贵的医疗和手术治疗之前尽早发现染色体分离的潜在问题。