Evolution of Homologous recombination mechanisms

同源重组机制的演变

基本信息

批准号：
9245713
负责人：
Galina Petukhova
金额：
$ 30.47万
依托单位：
HENRY M. JACKSON FDN FOR THE ADV MIL/MED
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-03-17 至 2020-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9245713
关键词：
Address Affect Alleles Aneuploidy Animals Automobile Driving Binding Biological Biological Process Birth Canis familiaris ChIP-seq Chromosomal Rearrangement Chromosome Segregation Chromosomes Congenital Abnormality DNA Binding Domain DNA Double Strand Break Data Defect Didelphidae Early Diagnosis Elements Enhancers Event Evolution Failure Fertility Gametogenesis Genes Genetic Recombination Genetic Transcription Genetic Variation Genomic Segment Genomics Health Heterozygote Histone H3 Human Hybrids Infertility Knockout Mice Lead Length Link Location Lysine Mammals Maps Measures Meiosis Modeling Monodelphis Monodelphis Domestica Mus N-terminal Nucleotides Organism Peptide Initiation Factors Population Prevention Process Proteins Pseudogenes Resolution Role Site Spontaneous abortion Sterility Vertebrates base functional genomics genetic information genetic variant genome-wide homologous recombination insight mouse model mutant promoter public health relevance segregation

项目摘要

DESCRIPTION (provided by applicant) Homologous recombination reshuffles genetic information between parental chromosomes generating genetic diversity and driving evolution. Recombination predominantly occurs at a set of genomic locations called recombination hotspots. In most mammals, including human, hotspot locations are defined by the sequence specific binding of the PRDM9 protein, which tri-methylates lysine 4 of the histone H3 at the sites where recombination is later initiated by the formation of DNA double stranded breaks (DSBs). In Prdm9 knockout mice DSBs are targeted to gene promoters and enhancers, which also carry an H3K4 trimethylation mark. Therefore, PRDM9 directs recombination away from functional genomic elements. This role is important as data indicate mutagenic effects of recombination both at the local nucleotide level and in gross chromosomal rearrangements. Prdm9 knockout mice are sterile with gametocytes eliminated shortly after induction of homologous recombination. Nevertheless, some mammals lack a canonical Prdm9 gene. What defines recombination hotspots in such species is currently unknown. To gain essential insights into possible mechanisms we propose to investigate the recombination landscape in two non-PRDM9 organisms and to determine the biological function of the KRAB domain of PRDM9 that may be expressed in these species. We will employ our ChIP/seq-based approach to build high-resolution genome-wide maps of DSB hotspots in (a) the dog and (b) the short-tailed opossum. We will compare these maps to the maps we recently generated for mice and human to determine the common and different features of DSB hotspots and their distributions in animals that have and that lack PRDM9. We will also generate two mouse models to determine the biological role of the KRAB domain of PRDM9. These will include (a) a mouse line expressing the truncated version of PRDM9 restricted to the N-terminal part of PRDM9 without the DNA binding domain (the form that is found in opossums) and (b) the line expressing full length PRDM9 with a mutant KRAB domain. We will evaluate both models with respect to their distribution of PRDM9-dependent H3K4me3 marks, the ability to initiate homologous recombination, the distribution of DSB hotspots, and the ability to complete recombination. In addition to the prominent role of homologous recombination in establishing the general genomic makeup of the population, recombination per se is essential for proper segregation of homologous chromosomes during gametogenesis. Recombination defects, including reduced recombination efficiency and improper placement of recombination events, are invariably associated with infertility, miscarriage and aneuploidy-related birth defects. Beyond the obvious health implications understanding of PRDM9 function is extremely important from an evolutionary point of view as Prdm9 is the only known speciation gene in vertebrates. Our studies aim to unravel the mechanisms that affect recombination efficiency and distribution in mammals, the factors that may interfere with recombination progression, and the mechanisms involved in mammalian speciation.

描述（由申请人提供）同源重组遗传信息与遗传多样性和多样性离子主要发生在大多数哺乳动物中称为重组热点的基因组位置。由DNA双链断裂（DSB）敲除小鼠DSB的形成启动，其针对基因启动子和增强子，这也带有H3K4三甲基化标记。在染色体重排的水平和总体上，有些哺乳动物都缺乏一个规范的PRDM9基因。在这些物种中，我们将采用基于芯片/SEQ的方法来构建（a）狗的高分辨率基因组MAPSB TS和（b）短尾巴。小鼠和人类在具有PRDM9的动物中确定DSB热点和thetributi的常见和不同的特征。 PRDM9的截短版本限制在prdm9的N末端部分（在负鼠中发现的形式）和（b）表达全长PRDM9的线，我们将使用突变的KRAB DOMAIN评估两个模型。它们的依赖性H3K4me3的分布与同源性重组的基因组构成在配子发生过程中的重要性相结合。与跨性别的脊椎动物中唯一已知的规格和分布，可能会干扰重组进展的因素，并且是prdm9的观点。