A Molecular View of Chromosome Recombination & Segregation in Eukaryotic Meiosis

染色体重组的分子视角

• 批准号: 9187460
• 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
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-12-10 至 2018-03-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9187460
• 关键词: Address; Adopted; Aneuploidy; Architecture; Area; Binding; Biochemical; Biological Assay; Biological Models; Cell division; Cells; Child; Chromosome Segregation; Chromosome Structures; Chromosomes; Chromosomes, Human, Pair 21; Clinical; Complex; Cytology; Defect; Dimerization; 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; Phenotype; Phosphotransferases; Point Mutation; Polymers; Pregnancy; Prevalence; Process; Property; Protein Engineering; Proteins; Public Health; Recombinant DNA; Reproduction; Role; Saccharomyces cerevisiae; Set protein; Signal Transduction; Sister; Spontaneous abortion; Structure; Synaptonemal Complex; Techniques; Testing; Trisomy; Work; X-Ray Crystallography; Yeasts; 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

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）： 减数分裂是一种特殊的细胞分裂程序，在有性生殖的生物体中产生配子。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联合、程序性重组和最终分离。虽然从遗传学和细胞学的角度很好地理解了这一过程，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染色体分离中的错误导致了绝大多数非整倍性，即后代中额外或缺失的染色体，这些染色体发生在超过一半的人类卵母细胞和5-10%的临床识别妊娠中。因此，非整倍体是流产和智力迟钝的主要遗传原因（例如，由21号染色体三体引起的唐氏综合征）。减数分裂I中染色体分离错误的根本原因还不清楚，进一步确定这些原因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，我们打算研究三组减数分裂染色体相关蛋白，它们对减数分裂I中染色体的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质和复合物的体外重建、这些复合物的3D结构分析以及靶向遗传分析来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S。酿酒酵母单核蛋白复合物，其在减数分裂I中结合染色体的动粒并修饰它们对纺锤体微管的附着，以使同源染色体能够正确定向和分离。我们将确定单核蛋白复合物的结构，并在遗传分析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 它们附着在一个微管上接下来，我们将研究保守的染色体相关蛋白Hop 1，它是每个染色体组织的蛋白质“轴”的一个组成部分。我们将研究Hop 1的保守的HORMA结构域，与纺锤体检查点蛋白Mad 2共享的信号传导结构域，在调节同源物间减数分裂重组，并在减数分裂特异性检查点监测重组的作用。最后，我们将研究联会复合体，一个重要的聚合物大会，连接同源物在减数分裂重组。由于对该复合物的结构及其功能知之甚少，我们将研究关键S的结构域结构、蛋白质-蛋白质相互作用和自组装决定因素。酿酒酵母联会复合体蛋白Zip 1。结合起来，这项工作将开始提供一个更准确的图片的大分子结构和相互作用的同源染色体重组和分离减数分裂I。