Molecular mechanisms for germline genome activation in C. elegans

线虫种系基因组激活的分子机制

• 批准号: 10092192
• 负责人: MATTHEW MICHAEL
• 金额: $ 33万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-02-01 至 2023-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10092192
• 关键词: Architecture; Attenuated; Back; Biological Models; Biology; Birth; Bypass; Caenorhabditis elegans; Cell Cycle; Cell Cycle Arrest; Cell Nucleus; Cell Proliferation; Cells; Chromatin; Chromatin Disassembly; Complex; Coupled; Cytology; DNA; DNA Damage; Dangerousness; Data; Development; Embryonic Development; Engineering; Enzymes; Event; Gene Activation; Gene Expression; Genes; Genetic; Genetic Transcription; Genome; Genome Components; Genomics; Germ Cells; HTATIP gene; Heterochromatin; Interphase Cell; Investigation; Ionizing radiation; Laboratories; Larva; Length; Measures; Mediating; Meiosis; Messenger RNA; Molecular; Nematoda; Nuclear; Nutrient; Organism; Pathway interactions; Play; Positioning Attribute; Process; Proteins; Publishing; Repression; Rest; Role; Signal Transduction; Site; Specific qualifier value; Structure; Structure of primordial sex cell; System; Time; Topoisomerase II; Transcriptional Activation; Transcriptional Regulation; Work; cell type; experimental study; fascinate; feeding; hatching; novel; recruit; whole genome

Project Summary/Abstract We are investigating a widespread and highly conserved, yet poorly understood, form of transcriptional control whereby gene expression on a global level is abruptly upregulated in a process termed genome activation. Our system is the developing germline of the nematode C. elegans, and thus we use genetics, genomics, and cytology to study how genome activation is controlled. Previously published and preliminary data from our group have outlined a genetic pathway for germline genome activation, whereby the topoisomerase II (TOP-2) enzyme is activated, in a signal-mediated manner, to produce programmed DNA breaks. The purpose of these breaks is to recruit the TIP60/RUVB regulator to chromatin, so that genome decompaction occurs, thereby facilitating genome activation. In this proposal we study three distinct components of the genome activation pathway that we have discovered. First, we study how genome architecture is established in primordial germ cells (PGCs) prior to activation. Our preliminary data suggest that whole-genome heterochromatization is the means by which this architecture is established and the means by which mRNA transcription is globally repressed in resting PGCs. We are unaware of any other examples in eukaryotic biology where heterochromatin formation is employed on such a grand scale, and thus these experiments are likely to supply a novel paradigm for how gene expression can be globally repressed in resting cells. We will also examine how TOP-2 is activated by signaling to go on and induce DNA breaks in the germline genome. It has been appreciated for some time that programmed DNA breaks occur in the genome during meiosis, however our discovery of programmed breaks occurring much earlier in germline development is unprecedented and worthy of detailed investigation. We plan to study how TOP-2 is regulated and we will also determine where in the genome the breaks are made. Successful completion of these experiments will provide a novel mechanism for programmed break formation that is likely to be relevant across cell types and organisms. A final set of experiments will examine how genome decompaction occurs. Our data show that the sole purpose of TOP-2 induced breaks is to recruit the TIP60/RUVB chromatin regulator to DNA so that decompaction can occur. Why PGCs take such extreme measures -- intentionally inducing a dangerous form of DNA damage into their genomes -- for the purpose of chromatin decompaction is a fascinating question. To get at this we will study how broken DNA recruits TIP60/RUVB and how the complex then decompacts chromatin. We will determine distance thresholds for positioning of engineered DNA breaks and target gene activation. Lastly, we will examine the exciting possibility that gene mobility within the nucleus is coupled to decompaction, and that mobility is important for transcriptional activation.

项目摘要/摘要 我们正在研究转录控制的广泛，高度保守但知之甚少的形式 在全球水平上的基因表达在称为基因组激活的过程中突然上调。我们的 系统是线虫C.秀隐岩的发展种系，因此我们使用遗传学，基因组学和 研究基因组激活如何控制的细胞学。先前发布的和我们的初步数据 组概述了种系基因组激活的遗传途径，拓扑异构酶II（TOP-2） 以信号介导的方式激活酶以产生编程的DNA断裂。这些目的 断裂是将TIP60/RUVB调节剂募集到染色质，以便发生基因组分解，从而发生 促进基因组激活。 在此提案中，我们研究了我们发现的基因组激活途径的三个不同组成部分。 首先，我们研究了在激活之前如何在原始生殖细胞（PGC）中建立基因组结构。我们的 初步数据表明，全基因组异性化是该体系结构的手段 建立和mRNA转录在静止的PGC中被全局抑制的手段。我们是 在真核生物学中没有任何其他例子 宏伟的规模，因此这些实验可能会为基因表达如何表达提供新的范式 在静息细胞中全球抑制。 我们还将检查如何通过发出信号进行并在种系中诱导DNA断裂来激活TOP-2 基因组。一段时间以来，人们对编程的DNA断裂发生在基因组中。 减数分裂，但是我们对种系开发中更早发生的程序性休息的发现是 前所未有的，值得进行详细调查。我们计划研究如何调节TOP-2，我们也将 确定在基因组中的位置进行断裂。这些实验的成功完成将提供 一种新型的编程断裂形成机制，可能在细胞类型和 有机体。 最后一组实验将检查基因组分解的发生方式。我们的数据表明唯一 TOP-2引起的休息的目的是将TIP60/RUVB染色质调节剂募集到DNA，以便 可能会发生分解。为什么PGC采取如此极端的措施 - 故意诱发危险形式 DNA损伤对其基因组的损害 - 出于染色质分解的目的是一个令人着迷的问题。到 解决这个问题，我们将研究损坏的DNA招募tip60/ruvb以及复合物如何分解 染色质。我们将确定用于定位工程DNA断裂和靶基因的距离阈值 激活。最后，我们将研究核中基因迁移率与 分解，这种迁移率对于转录激活很重要。