Mechanisms of chromosome motility during mammalian meiosis

哺乳动物减数分裂过程中的染色体运动机制 项目摘要/摘要 减数分裂是生殖系细胞分裂的一种特殊形式，它产生有性生殖所必需的单倍体配子。 繁殖。减数分裂的关键步骤是同源染色体之间的重组，也称为 减数分裂交叉，需要将染色体适当地分离到子代细胞中。不完美 分离通过减数分裂阻止进展，是不孕和流产的危险因素。一个详细的 对减数分裂交叉的理解将增强对减数分裂的认识，并对人类具有重要意义 生殖生物学。减数分裂交叉的关键是细胞中的重塑过程，这涉及到连接 细胞核中的染色体通过跨越细胞核的蛋白质-蛋白质相互作用而影响胞浆中的动力蛋白 信封。这一事件允许动力蛋白沿着核膜移动所有染色体，以促进 同源染色体的搜索和配对以进行交换。这一过程中的一个关键角色是 SUN1-KASH5 LINC复合体，跨越核膜连接染色体和动力蛋白。尽管 哺乳动物减数分裂中染色体-核膜被膜拴系和运动的重要性 造成这一现象的机制还很欠缺。了解SUN1-KASH5如何进行减数分裂- 特定的功能将产生新的知识，以改善生育障碍的诊断和治疗。 使用多学科方法，包括生化/生物物理方法、固定细胞和活细胞 显微镜、单分子TIRF显微镜、膜蛋白重建和一只专门的小鼠 减数分裂模型系统，这项建议旨在了解动力蛋白如何移动染色体以促进 减数分裂过程中的同源配对。提案的目标1将确定结构基础、动态和 KASH5-dynein相互作用的减数分裂专一性有助于交换。在鼠标中审问 精母细胞将补充体外研究，以揭示KASH5-动力蛋白相互作用如何帮助维持 老鼠的繁殖力。本提案的目标2将确定SUN1-KASH5在 核膜以及它们如何使胞质动力蛋白力量移动细胞核内的整个染色体。 这一目标和拨款提案最终导致了对导致不孕不育的分子机制的剖析 人类是由编码KASH5的基因突变引起的。拟议的研究将揭示动力蛋白和 在哺乳动物减数分裂过程中，LINC复合体聚集在一起，促进了必要的交换过程。

Mechanisms of chromosome motility during mammalian meiosis Project Summary/Abstract Meiosis is a specialized form of cell division of the germline that produces haploid gametes essential for sexual reproduction. A critical step in meiosis is the recombination between homologous chromosomes, also called meiotic crossover, required for the proper segregation of chromosomes into the daughter cells. Imperfect segregation prevents progression through meiosis and is a risk factor for infertility and miscarriage. A detailed understanding of meiotic crossover will enhance the knowledge of meiosis and hold implications for human reproductive biology. Essential to meiotic crossover is a remodeling process in the cell that involves connecting chromosomes in the nucleus to dynein in the cytosol via protein-protein interactions spanning the nuclear envelope. This event allows dynein to move all chromosomes along the nuclear envelope to facilitate the search and pairing of homologous chromosomes for undergoing crossover. A key player in this process is the SUN1-KASH5 LINC complex that spans the nuclear envelope to link chromosomes to dynein. Despite the importance of chromosome-nuclear envelope tethering and motility in mammalian meiosis, a molecular mechanism for this phenomenon is still lacking. Understanding how SUN1-KASH5 performs its meiosis- specific function will generate new knowledge to improve the diagnosis and treatment of fertility disorders. Using a multi-disciplinary approach that includes biochemical/biophysical methods, fixed and live-cell microscopy, single-molecule TIRF microscopy, membrane protein reconstitution, and a specialized mouse meiosis model system, this proposal aims to understand how dynein moves chromosomes to facilitate homolog pairing during meiosis. Aim 1 of the proposal will determine the structural basis, the dynamics, and the meiosis-specificity of the KASH5-dynein interaction instrumental to crossover. Interrogation in mouse spermatocytes will complement the in vitro studies to reveal how the KASH5-dynein interaction helps uphold mouse fertility. Aim 2 of this proposal will determine the higher-order structures adopted by SUN1-KASH5 at the nuclear envelope and how they enable cytosolic dynein forces to move entire chromosomes in the nucleus. This Aim and the grant proposal culminate in the dissection of the molecular mechanism underlying infertility in humans caused by a mutation in the gene encoding KASH5. The proposed studies will reveal how dynein and LINC complexes come together to facilitate the essential process of crossover during mammalian meiosis.