A Molecular View of Chromosome Recombination & Segregation in Eukaryotic Meiosis

染色体重组的分子视角

基本信息

批准号：
8975783
负责人：
Kevin Daniel Corbett
金额：
$ 30.95万
依托单位：
LUDWIG INSTITUTE FOR CANCER RES LTD
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-12-10 至 2017-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8975783
关键词：
Accounting Address Adopted Aneuploidy Architecture Area Binding Biochemical Biological Assay Cell division Cells Child Chromosome Segregation Chromosome Structures Chromosomes Chromosomes, Human, Pair 21 Complex Crystallography Defect Dissection Down Syndrome Electron Microscopy Embryo Engineering Ensure Equilibrium Event Evolution Failure Genetic Genetic Recombination Geometry Germ Cells Head Homologous Gene Human In Vitro Individual Infertility Kinetochores Link Mediating Meiosis Meiotic Recombination Mental Retardation Microtubules Molecular Molecular Conformation Molecular Structure Monitor Mutation Nature Negative Staining Oocytes Organism Peptides Phosphotransferases Point Mutation Pregnancy Prevalence Process Property Protein Engineering Proteins Public Health Recombinant DNA Reproduction Role Saccharomyces cerevisiae Set protein Signal Transduction Sister Spontaneous abortion Staging Structure Synaptonemal Complex Techniques Testing Trisomy Work Yeast Model System crosslink design developmental disease dimer fertility improvement in vivo mutant offspring programs protein complex protein protein interaction protein structure public health relevance reconstitution segregation self assembly stoichiometry three dimensional structure

项目摘要

DESCRIPTION (provided by applicant): PROJECT SUMMARY Meiosis is a specialized cell division program that gives rise to gametes in sexually reproducing organisms. The first stage of meiosis, called meiosis I, uniquely involves the association, programmed recombination, and eventual segregation of homologous chromosomes. While this process is well understood from a genetic and cytological standpoint, our understanding of how the meiosis-specific cellular machinery is able to organize and manipulate meiotic chromosomes in 3D space to mediate their proper segregation remains a mystery. This area of study is significant, as errors in meiosis I chromosome segregation account for the vast majority of aneuploidies, extra or missing chromosomes in offspring, that occur in over half of human oocytes and 5-10% of clinically recognized pregnancies. As such, aneuploidy is the leading genetic cause of miscarriage and of mental retardation (e.g. Down syndrome, caused by trisomy of chromosome 21). The underlying causes of chromosome segregation errors in meiosis I are not well understood, and further progress toward identifying these causes will require a detailed understanding of the molecular mechanisms of meiosis-specific chromosome segregation machinery. Here, we propose to study three sets of meiotic chromosome-associated proteins that are critical for different aspects of chromosomes' organization and physical manipulation in meiosis I. Our approach combines in vitro reconstitution of purified proteins and complexes, 3D structural analysis of these complexes, and targeted genetic assays to test mutants designed to disrupt specific aspects of these proteins' structures and interactions. We will first study the S. cerevisiae monopolin complex, which binds chromosomes' kinetochores in meiosis I and modifies their attachments to spindle microtubules, to enable the proper orientation and segregation of homologous chromosomes. We will determine the architecture of the monopolin complex, and use engineered protein constructs in genetic assays to test whether it directly cross-links sister kinetochores to mediate their attachment to a single microtubule. Next, we will study the conserved chromosome-associated protein Hop1, a component of the proteinaceous "axis" about which each chromosome is organized. We will examine the roles of Hop1's conserved HORMA domain, a signaling domain shared with the spindle checkpoint protein Mad2, in regulating inter-homolog meiotic recombination, and in a meiosis-specific checkpoint monitoring recombination. Finally, we will study the synaptonemal complex, an essential polymeric assembly that links homologs together during meiotic recombination. As very little is known about the architecture of this complex or its functions, we will study the domain structure, protein-protein interactions, and self-assembly determinants of the key S. cerevisiae synaptonemal complex protein Zip1. Combined, this work will begin to provide a more accurate picture of the macromolecular structures and interactions underlying homologous chromosome recombination and segregation in meiosis I.

描述（由申请人提供）：项目摘要减数分裂是一种特殊的细胞分裂程序，可在有性生殖生物体中产生配子。减数分裂的第一阶段称为减数分裂 I，独特地涉及同源染色体的关联、程序重组和最终分离。虽然从遗传学和细胞学的角度来看这个过程已经被很好地理解，但我们对减数分裂特异性细胞机制如何能够在 3D 空间中组织和操纵减数分裂染色体以介导其正确分离的理解仍然是一个谜。这一研究领域意义重大，因为减数分裂 I 染色体分离的错误导致了绝大多数非整倍体，即后代染色体的额外或缺失，这种情况发生在超过一半的人类卵母细胞和 5-10% 的临床认可的妊娠中。因此，非整倍体是流产和智力低下（例如由 21 号染色体三体引起的唐氏综合症）的主要原因。减数分裂 I 中染色体分离错误的根本原因尚不清楚，识别这些原因的进一步进展需要详细了解减数分裂特异性染色体分离机制的分子机制。在这里，我们建议研究三组减数分裂染色体相关蛋白，它们对于减数分裂 I 中染色体组织和物理操作的不同方面至关重要。我们的方法结合了纯化蛋白和复合物的体外重建、这些复合物的 3D 结构分析、并进行有针对性的基因检测，以测试旨在破坏这些蛋白质结构和相互作用的特定方面的突变体。我们将首先研究酿酒酵母单孢子复合体，它在减数分裂 I 中结合染色体的动粒并修改它们与纺锤体微管的附着，以使同源染色体能够正确定向和分离。我们将确定单粒蛋白复合物的结构，并在基因检测中使用工程蛋白构建体来测试它是否直接交联姐妹动粒来介导它们附着在单个微管上。接下来，我们将研究保守的染色体相关蛋白 Hop1，它是每条染色体围绕其组织的蛋白质“轴”的一个组成部分。我们将研究 Hop1 的保守 HORMA 结构域（与纺锤体检查点蛋白 Mad2 共享的信号传导结构域）在调节同源减数分裂间重组以及减数分裂特异性检查点监测重组中的作用。最后，我们将研究联会复合体，这是减数分裂重组过程中将同源物连接在一起的重要聚合体。由于对该复合物的结构或其功能知之甚少，我们将研究关键的酿酒酵母联会复合物蛋白 Zip1 的结构域结构、蛋白质-蛋白质相互作用和自组装决定因素。结合起来，这项工作将开始提供关于减数分裂 I 中同源染色体重组和分离的大分子结构和相互作用的更准确的图像。