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

基本信息

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
项目类别：
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

项目摘要

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.

减数分裂重组导致形成DNA跨界（CO），这对于确保正确的在第一个减数分裂部门的同源（母亲和父亲）染色体的分离。染色体隔离错误显示出惊人的性二态性：在人类中，20-80％的卵与2.5-7％的精子为非整倍体，很大程度上可能是由于CO形成错误。减数分裂重组是由形成开始的 DNA双链断裂（DSB），然后通过各种途径修复以实现严格调节 COS在整个基因组中的频率和分布。这些DSB维修事件发生在突发型复合物（SC），一种沿着染色体轴形成的蛋白质结构，束缚同源对在一起。 SC长度与CO数量密切相关，大多数研究在人和小鼠中报告女性由于SC的较长长度而具有较高的CO率。矛盾的是，减数分裂重组女性高度容易出错，这意味着CO形成中的批判性别差异不能用与SC长度相关。我假设CO的性二态性是关键的产物减数分裂预言I的分子特征差异，即协调减数分裂的因素重组和染色体轴组件。与普通实验室小鼠（例如B6）和人类不同，尽管SC较短，但野生PWD雄性小鼠的CO数量较高，这挑战了教条 CO率与SC长度密不可分。因此，我建议使用来自各种遗传背景，以剖析性二态CO的分子和遗传因素费率。在AIM 1中，我将检查男性和女性PWD中减数分裂重组蛋白的动态定位和B6小鼠，以阐明二态CO速率如何通过预言逐渐表现出来。高分辨率成像方法，我将表征关键DSB修复因子的积累（包括 RAD51，RPA2，MSH4，RNF212和MLH1）在CO调节中查明性二态差异。在 AIM 2，我将评估男性和雌性B6和PWD小鼠中粘蛋白介导的染色质组织。使用剪切和标签到剖面REC8和RAD21L粘蛋白分布，我将确定粘蛋白轴的性别差异组装及其与早期DSB修复中间体的相关性。在AIM 3中，我将使用重组协作交叉的小鼠线，以绘制与CO数字的性别差异相关的遗传基因座 SC长度。总的来说，这些研究将是第一个研究分子和遗传因素的研究在各种小鼠遗传背景下影响性二态CO率和SC长度。洞察力获得了从这个项目中，将对为什么重组错误在女性中更常见。在这个项目的整个过程中，我将获得宝贵的培训，以使用超分辨率显微镜，基因组学数据的计算分析以及复杂性状的定量遗传学。以及职业开发指导，这些技能对于我的独立研究计划的发展至关重要。