Development of a lacO/lacI based fluorescence reporter-operator system to study chromosome dynamics and double-strand break repair in mouse meiosis.

总结 非整倍体配子的受精通常会导致妊娠丢失或唐氏综合征等疾病。 非整倍性发生在10-30%的人类配子中，并且通常由染色体分离错误引起， 减数分裂减数分裂事件，如同源染色体配对、双链断裂（DSB）、重组 以及杂交的形成，确保染色体的正确分离。然而， 对这些事件的调控机制还不完全了解。因此，目前几乎没有战略， 预测或防止配子发生过程中的非整倍体。为了克服该领域的一些局限性，我们建立了 基于lac操纵子-lac阻遏子（lacO-lacR）范例的荧光操纵子-操纵子系统（FROS）， 这使得蛋白质能够靶向不同的基因组区域。我们的长期目标是阐明 在减数分裂过程中调节染色体分离，从而确保配子的形成， 核型目的1利用FROS技术研究小鼠精母细胞I期前期染色体的快速运动.我们 还将联合收割机FROS与长期的曲细精管染色体运动的三维测量相结合， 直接测试同源染色体配对是否来自于越来越多的生产性相互作用（缫丝 in），而不是瞬时交互的重复循环（捕获和释放）。此外，我们将分析突变体 精母细胞的FROS，以确定如何关键球员，包括核骨架的连接器的组件 和细胞骨架（LINC）复合体和联会复合体，影响同源和非同源 在特定位点的相互作用。动力蛋白和微管与LINC复合物相互作用， RPM。目标2将确定支持这些运动的其他电机和细胞骨架组件， 基于我们的初步数据，我们发现驱动蛋白是参与生成 RPM。我们将用无偏的蛋白质组学方法、功能测定和FROS来扩展这些发现， 破译控制同源配对的动力学目标3将研究潜在的机制， ANKRD 31和pro-DSB因子在重组热点之间的关联。使用FROS，我们将针对 ANKRD 31-GFP-lacI在精母细胞中的lacO区域，我们预测这将招募前DSB因子， 重组蛋白我们还将分析ANKRD 31-GFP-lacI对下游重组的影响， 在lacO位点的中间体。这项拟议中的研究将首次揭示染色体环境如何影响 染色体分离的潜在机制，从而推进了对基本减数分裂的新认识 非整倍体的过程和原因。

SUMMARY Fertilization of aneuploid gametes often leads to pregnancy loss or disorders such as Down’s syndrome. Aneuploidy occurs in 10-30% of human gametes and typically arises from chromosome segregation errors during meiosis. Meiotic events such as homologous chromosome pairing, double strand breaks (DSBs), recombination and the formation of crossovers, ensure proper chromosome segregation. Nevertheless, the mechanisms that regulate these events are incompletely understood. Consequently, there are currently few to no strategies to predict or prevent aneuploidy during gametogenesis. To overcome some limitations in the field, we established a fluorescence reporter-operator system (FROS) based on the lac operator-lac repressor (lacO-lacR) paradigm, which enables protein targeting to distinct genomic regions. Our long-term goal is to elucidate the mechanisms that regulate chromosome segregation during meiosis and thus ensure the formation of gametes with a normal karyotype. Aim 1 use FROS to dissect rapid chromosome motions in mouse spermatocytes at prophase I. We will also combine FROS with long-term 3D measurements of chromosome motions in seminiferous tubules to directly test whether homologous chromosome pairing arises from increasingly productive interactions (reeling in), versus reiterative rounds of transient interactions (catch and release). Additionally, we will analyze mutant spermatocytes by FROS to determine how key players, including components of the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex and the synaptonemal complex, affect homologous and non-homologous interactions at specific loci. Dynein and microtubules interact with the LINC complex and are known to contribute to RPMs. Aim 2 will identify additional motors and cytoskeleton components that support these movements, building on our preliminary data uncovering kinesins as candidate molecular motors involved in generating RPMs. We will extend these findings with unbiased proteomic approaches, functional assays and FROS to decipher the dynamic forces that govern homolog pairing. Aim 3 will investigate the mechanism underlying the association between ANKRD31 and pro-DSB factors at recombination hotspots. Using FROS, we will target ANKRD31-GFP-lacI to the lacO region in spermatocytes, which we predict will recruit pro-DSB factors and recombination proteins. We will also analyze the effect of ANKRD31-GFP-lacI on downstream recombination intermediates at lacO sites. The proposed research will for the first time discern how chromosome context affects the mechanisms underlying chromosome segregation and thus advance new knowledge of fundamental meiotic processes and the causes of aneuploidy.