Uncovering molecular factors driving sexual dimorphism in crossing over in diverse mouse genetic backgrounds

揭示不同小鼠遗传背景交叉中驱动性别二态性的分子因素

• 批准号: 10722746
• 负责人: Tegan Sonia-Adeline Horan
• 金额: $ 10.9万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-19 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10722746
• 关键词: Address; Affect; Aneuploidy; Automobile Driving; Candidate Disease Gene; Chromatin; Chromosome Mapping; Chromosome Pairing; Chromosome Segregation; Chromosomes; Complex Genetic Trait; Computer Analysis; Congenital Abnormality; DNA; DNA Double Strand Break; Data; Development; Development Plans; Double Strand Break Repair; Ensure; Event; Exhibits; Female; Frequencies; Future; Genes; Genetic; Genetic Crossing Over; Genetic Recombination; Genetic Variation; Genome; Goals; Heritability; Heterozygote; Homeostasis; Homologous Gene; Human; Inbred Strains Mice; Incidence; Infertility; Laboratory mice; Learning; Length; Link; MLH1 gene; MSH4 gene; Male Sterility; Male Sterilizations; Maps; Mediating; Meiosis; Meiotic Prophase I; Meiotic Recombination; Mentors; Molecular; Mouse Strains; Mus; Mutation; Oocytes; Organism; Pathway interactions; Pattern; Phase; Phenotype; Proteins; Quantitative Genetics; Quantitative Trait Loci; Recombinants; Regulation; Reporting; Research; Resolution; Role; SPO11 gene; Screening Result; Severities; Sex Differences; Site; Spermatocytes; Spontaneous abortion; Stains; Sterility; Structure; Synaptonemal Complex; Techniques; Training; Variant; Work; age related; career development; cohesin; cohesion; dosage; egg; genetic association; genomic data; genomic locus; high resolution imaging; imaging modality; insight; male; mouse genetics; mouse model; mutant; nuclease; programs; repaired; segregation; sex; sexual dimorphism; skills; sperm cell; superresolution microscopy

Meiotic recombination results in the formation of DNA crossovers (CO) that are critical for ensuring the correct segregation of homologous (maternal and paternal) chromosomes at the first meiotic division. Chromosome segregation errors show striking sexual dimorphism: In humans, 20-80% of eggs versus 2.5-7% of sperm are aneuploid, likely due in large part to errors in CO formation. Meiotic recombination is initiated by the formation of DNA double strand breaks (DSB) that are then repaired via various pathways to achieve a tightly regulated frequency and distribution of COs across the genome. These DSB repair events occur in the context of the synaptonemal complex (SC), a proteinaceous structure that forms along the chromosome axes, tethering homolog pairs together. SC length correlates strongly with CO number, and most studies in human and mouse report females have higher CO rates due to their longer SC length. Paradoxically, meiotic recombination in females is highly error-prone, implying critical sex differences in CO formation cannot be explained by a correlation with SC length. I hypothesize that sexual dimorphism in CO rates is the product of key differences in molecular features of meiotic prophase I, namely the factors that orchestrate meiotic recombination and chromosome axis assembly. Unlike common laboratory mice (e.g., B6) and humans, wild-derived PWD male mice have higher CO number despite their shorter SCs, challenging the dogma that CO rates are inextricably linked to SC length. Thus, I propose to address my hypothesis using mice from diverse genetic backgrounds to dissect the molecular and genetic factors underlying sexually dimorphic CO rates. In Aim 1, I will examine dynamic localization of meiotic recombination proteins in male and female PWD and B6 mice to elucidate how sexually dimorphic CO rates progressively manifest through prophase I. Using high resolution imaging methods, I will characterize the accumulation of critical DSB repair factors (including RAD51, RPA2, MSH4, RNF212, and MLH1) to pinpoint sexually dimorphic differences in CO regulation. In Aim 2, I will evaluate cohesin-mediated chromatin organization in male and female B6 and PWD mice. Using CUT&Tag to profile REC8 and RAD21L cohesin distributions, I will identify sex differences in cohesin axis assembly and how they correlate with early DSB repair intermediates. In Aim 3, I will use the recombinant mouse lines of the Collaborative Cross to map genetic loci associated with sex differences in CO number and SC length. Collectively, these studies will be the first to examine the molecular and genetic factors that influence sexually dimorphic CO rate and SC length in diverse mouse genetic backgrounds. Insights gained from this project will provide critical understanding of why recombination errors are more common in females. Over the course of this project, I will receive invaluable training in the use of super-resolution microscopy, computational analysis of genomics data, and quantitative genetics of complex traits. Along with career development mentoring, these skills will be critical to the development of my independent research program.

减数分裂重组导致DNA交换（CO）的形成，这对于确保正确的DNA交换是至关重要的。 在第一次减数分裂时同源染色体（母本和父本）的分离。染色体 分离错误显示出惊人的两性异形：在人类中，20-80%的卵子和2.5-7%的精子是两性异形。 非整倍体，可能在很大程度上是由于CO形成中的错误。减数分裂重组是由 DNA双链断裂（DSB），然后通过各种途径修复，以实现严格调控的 基因组中CO的频率和分布。这些DSB修复事件发生在 联会复合体（SC），是一种蛋白质结构，沿着染色体轴形成， 同源配对在一起。SC长度与CO数量密切相关，大多数人和小鼠的研究 报告女性由于SC长度较长而具有较高的CO率。巧合的是， 女性是非常容易出错的，这意味着关键的性别差异，在CO的形成不能解释的是， 与SC长度相关。我假设CO比率的两性异形是关键因素的产物， 减数分裂前期I分子特征的差异，即协调减数分裂的因素 重组和染色体轴组装。与普通实验室小鼠（例如，B6）和人类， 野生型PWD雄性小鼠尽管SC较短，但CO数量较高，这挑战了 CO率与SC长度密不可分。因此，我建议使用来自 不同的遗传背景，以剖析性二态性CO的分子和遗传因素 rates.在目的1中，我将研究减数分裂重组蛋白在男性和女性PWD中的动态定位 和B6小鼠，以阐明性二态性CO率如何通过前期I逐渐显现。使用 高分辨率成像方法，我将表征关键DSB修复因子（包括 RAD 51、RPA 2、MSH 4、RNF 212和MLH 1）来确定CO调节中的性二态差异。在 目的2，我将评估在雄性和雌性B6和PWD小鼠中粘附蛋白介导的染色质组织。使用 CUT&Tag分析REC 8和RAD 21 L粘附蛋白分布，我将确定粘附蛋白轴的性别差异 组装以及它们如何与早期DSB修复中间体相关。在目标3中，我将使用重组 小鼠品系的协作杂交，以绘制与CO数量和 SC长度。总的来说，这些研究将是第一次检查分子和遗传因素， 影响不同遗传背景小鼠性二态性CO率和SC长度。获得的见解 从这个项目将提供关键的理解，为什么重组错误是更常见的女性。 在这个项目的过程中，我将接受使用超分辨率显微镜的宝贵培训， 基因组学数据的计算分析和复杂性状的数量遗传学。沿着事业 发展指导，这些技能将是至关重要的发展，我的独立研究计划。