Germline mutagenesis at meiotic double-strand breaks

项目总结/摘要 减数分裂重组对于哺乳动物生殖细胞中的减数分裂是必需的，因此对于哺乳动物生殖细胞中的减数分裂是必需的。 单倍体配子的发育，即，精子和卵子双链DNA是由数百个双链DNA启动的， 链断裂（DSB）在全基因组范围内引入，其由SPO 11蛋白催化。忠实传递 将基因组的DNA复制到后代需要对这些众多的DSB进行适当的修复，主要是通过 与同源物重组。在减数分裂细胞中，DSB的形成受ATM激酶的调节，ATM激酶是 已知是有丝分裂细胞中DSB的主要应答者，使得在不存在ATM的情况下，减数分裂DSB 增加~10倍。 我们最近发现，减数分裂DSB有引发生殖系重排的风险， 涉及非同源末端连接的特定缺失和串联重复，特别是在缺乏 大气压这些事件也会破坏这些热点发生的基因 作为相关的PRDM 9结合位点，其控制这些基因座处的重组。因此，我们的发现揭示了 以前隐藏的可能影响人类健康和基因组的生殖系诱变潜力 进化在人类中，最近对冰岛人的长距离测序支持了这种影响。该提案追求 旨在了解引起这些事件的机制，减数分裂DSB事件的范围， 年龄的影响。我们假设在减数分裂DSB中可能存在其他重排， 以前确定过。因此，在第一个目标中，我们建议确定可能产生的致突变结果的范围 由减数分裂DSB引起，包括长距离缺失和复制以及染色体易位。在 第二个目的，我们研究可能影响缺失形成的因素。我们专注于DNA的影响 端部处理分两步进行，即去除SPO 11和端部处理，以及重组。此外，我们解决 在附近DSB处形成的缺口是否是同源重组的底物，以及父本基因的影响。 减数分裂DSB重排事件的年龄。

Project Summary/Abstract Meiotic recombination is essential for the reductional cell division in mammalian germ cells and thus for the development of haploid gametes, i.e., sperm and eggs. Recombination is initiated by hundreds of DNA double- strand breaks (DSBs) introduced genome-wide that are catalyzed by the SPO11 protein. Faithful transmission of the genome to subsequent generations requires proper repair of these numerous DSBs, primarily through recombination with the homolog. DSB formation is regulated in meiotic cells by the ATM kinase, which is known to be a primary responder to DSBs in mitotic cells, such that in the absence of ATM, meiotic DSBs increase ~10-fold. We recently discovered that meiotic DSBs are at risk for provoking germline rearrangements, in particular deletions and tandem duplications involving nonhomologous end-joining, especially in the absence of ATM. These events are consequential in terms of disrupting the genes in which these hotspots occur as well as the associated PRDM9 binding sites that govern recombination at those loci. Thus, our findings reveal a previously hidden potential for germline mutagenesis that is likely to affect human health and genome evolution. In humans, recent long-range sequencing of Icelanders supports this impact. This proposal pursues aims to understand the mechanisms that give rise to these events, the range of events at meiotic DSBs, and the effect of age. We hypothesize that other rearrangements are possible at meiotic DSBs than what we have previously identified. Thus, in the first aim, we propose to determine the range of mutagenic outcomes that can arise from meiotic DSBs, including long-range deletions and duplications and chromosomal translocations. In the second aim, we examine factors that may impact the formation of deletions. We focus on the effect of DNA end processing at two steps, SPO11 removal and end processing, and recombination. Further, we address whether gaps formed at nearby DSBs are substrates for homologous recombination and the impact of paternal age in the rearrangement events at meiotic DSBs.