Mechanisms of Chromosome Scale Signal Propagation

染色体尺度信号传播的机制

• 批准号: 10001534
• 负责人: Andreas Hochwagen
• 金额: $ 31.27万
• 依托单位: NEW YORK UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-01 至 2023-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10001534
• 关键词: ATP phosphohydrolase; Animal Model; Binding; Birds; Cells; Chromatin; Chromosomal Breaks; Chromosomal Instability; Chromosome Segregation; Chromosomes; Communication; Congenital Abnormality; Cytology; DNA; DNA Double Strand Break; Dangerousness; Data; Defect; Double Strand Break Repair; Down Syndrome; Down-Regulation; Edward' s syndrome; Ensure; Event; Fertility; Funding; Genes; Genetic; Genetic Epistasis; Genetic Nondisjunction; Genetic Recombination; Genetic Transcription; Genetic Variation; Genome; Genomic Segment; Genomics; Germ Cells; Goals; Human; Human Chromosomes; Incidence; Infertility; Lead; Length; Mammals; Meiosis; Meiotic Recombination; Microscopy; Modeling; Molecular; Nuclear; Nuclear Envelope; Nuclear Pore; Organism; Pan Genus; Pattern; Process; Production; Prophase; Proteins; Regulation; Research; Resistance; Resolution; Rest; Risk; Role; Saccharomyces cerevisiae; Signal Transduction; Structure; Synaptonemal Complex; Testing; Work; Yeasts; egg; enzyme activity; experimental study; genome integrity; genome-wide analysis; improved; insight; interstitial; novel; repaired; segregation; sperm cell; telomere; tumor progression

Project summary The overall goal of this project is to determine how cells communicate chromosome break formation and repair across large chromosomal distances. DNA double-strand breaks (DSBs) are dangerous insults to genome integrity because of their potential to cause chromosome rearrangements and chromosome instability, both of which are strongly associated with cancer progression as well as birth defects. Remarkably, meiotic cells are able to efficiently orchestrate the formation and repair of hundreds of concurrent DSBs across their genome during meiotic recombination, a process that is essential for proper gamete formation and fertility. A key feature of meiotic DSB formation and repair is its coordination at the chromosomal level. In the previous funding period we provided evidence that the synaptonemal complex, a conserved protein lattice that forms between aligned homologous chromosomes in late meiotic prophase, communicates repair decisions along meiotic chromosomes in S. cerevisiae. We showed that this communication resulted in reduced DSB formation as well as simplified repair, and we identified several factors involved in this process. We now discovered the existence of privileged genomic regions near the ends of all chromosomes that appear resistant to regulation by the synaptonemal complex. These end-adjacent regions (EARs) cover large genomic distances (~100kb, which is nearly half the length of the shortest chromosome) and continue to form and repair DSBs well after DSB formation has stopped in the rest of the genome. Similar regions of elevated meiotic recombination are also observed in birds, chimps, and humans. The goal of this project is to define the chromosomal signal that generates these regions and to test if EARs help inheritance of short chromosomes. Our preliminary analyses suggest several roles of the nuclear envelope, both in the establishment of the EARs and in the suppression of DSBs in the rest of the genome. The dynamics of chromosomal signaling and its interaction with the nuclear envelope will be analyzed by genome-wide binding studies and super-resolution microscopy, taking advantage of a conditional nuclear depletion approach that we recently introduced into meiotic cells that allows stage-specific knock-downs of pleiotropic nuclear factors. In addition, signal integration will be analyzed using genetic epistasis analyses, cytology, and physical analysis of DSB formation. As EARs cover a proportionally much larger fraction of short chromosomes, the proposal will also use tetrad sequencing to test if these regions drive the widely observed increase in recombination rates on short chromosomes. Fluorescent marker segregation will be used to determine if EARs differentially improve the meiotic segregation fidelity of short chromosomes. Together, these analyses will provide key insights into the mechanisms of chromosomal signal propagation, and open new avenues for understanding the origins of birth defects such as Down syndrome (trisomy 21) and Edwards syndrome (trisomy 18), which are caused by meiotic missegregation of short chromosomes.

项目总结 这个项目的总体目标是确定细胞如何传递染色体断裂形成和 跨越很大的染色体距离进行修复。DNA双链断裂(DSB)是对 基因组的完整性，因为它们有可能导致染色体重排和染色体不稳定， 这两者都与癌症进展和出生缺陷密切相关。值得注意的是，减数分裂 单元能够高效地协调数百个并发DSB的形成和修复 基因组在减数分裂重组过程中，这一过程对于正确的配子形成和生育是必不可少的。 减数分裂DSB形成和修复的一个关键特征是它在染色体水平上的协调。在 在之前的资助期间，我们提供了证据表明，联会复合体是一种保守的蛋白质晶格， 减数分裂晚期同源染色体之间的排列形式，传达修复决定 沿着酿酒酵母的减数分裂染色体。我们表明，这种通信降低了DSB 形成以及简化修复，我们确定了这一过程中涉及的几个因素。我们现在 发现在所有表现为抗性的染色体末端附近存在特权基因组区域 受到联会复合体的调节。这些末端相邻区域(耳朵)覆盖了大的基因组 距离(~100kb，几乎是最短染色体长度的一半)，并继续形成和修复 DSB的形成在基因组的其余部分停止后很久。相似区域的高水平减数分裂 重组也在鸟类、黑猩猩和人类身上观察到。 该项目的目标是定义产生这些区域的染色体信号，并测试 耳朵有助于短染色体的遗传。我们的初步分析表明，核的几个作用 包膜，在耳朵的建立和在基因组的其余部分抑制DSB中都是如此。 染色体信号的动力学及其与核膜的相互作用将通过 全基因组结合研究和超分辨率显微镜，利用条件核 我们最近引入减数分裂细胞的耗竭方法，允许特定阶段的敲除 多效性核因子。此外，信号整合将使用遗传上位性分析进行分析， 细胞学和DSB形成的物理分析。因为耳朵覆盖短耳朵的比例要大得多 染色体，该提案还将使用四分体测序来测试这些区域是否驱动了广泛观察到的 短染色体重组率的提高。荧光标记分离将用于 确定耳朵是否差异地提高了短染色体减数分裂的保真度。加在一起，这些 分析将提供对染色体信号传播机制的关键见解，并打开新的 了解唐氏综合征(21三体)和爱德华兹等出生缺陷起源的途径 综合征(18三体)，由减数分裂短染色体的错误分离引起。