Regulation of zygotic genome activation by Zelda

Zelda 对合子基因组激活的调控

• 批准号: 8601708
• 负责人: CHRISTINE A RUSHLOW
• 金额: $ 30.81万
• 依托单位: NEW YORK UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8601708
• 关键词: 3' Untranslated Regions; Binding; Binding Sites; Biochemical; Biological Assay; Biological Models; Cell Cycle Regulation; Cell Nucleus; Chromatin; Competence; Complex; Consensus; DNA; DNA Binding; Development; Developmental Process; Dosage Compensation (Genetics); Drops; Drosophila genus; Embryo; Enhancers; Epigenetic Process; Event; Experimental Designs; Fertilization; Future; Gene Activation; Gene Expression; Gene Expression Profile; Gene Targeting; Genes; Genetic; Genetic Transcription; Genome; Genomics; Global Change; Goals; Grant; Hour; In Vitro; Lead; Mediating; Messenger RNA; MicroRNAs; Molecular Genetics; Monitor; Mothers; Nuclear Protein; Nucleosomes; Organism; Pattern; Play; Polymerase; Positioning Attribute; Process; Protein Dynamics; Proteins; RNA Degradation; RNA Polymerase II; Reagent; Recruitment Activity; Regulation; Regulator Genes; Relative (related person); Reporter; Repression; Role; Shapes; Signal Transduction; Site; Spottings; Staging; Study models; System; Testing; Time; Transcription Initiation Site; Transcription factor genes; Transcriptional Activation; Transgenes; Untranslated Regions; Zinc Fingers; base; chromatin remodeling; embryonic protein; feeding; histone modification; morphogens; mutant; novel; programs; public health relevance; research study; response; sensor; sex determination; tool; transcription factor

DESCRIPTION (provided by applicant): There is much about early development that is not understood. At some point after fertilization the zygotic genome is activated, and genes that are necessary for upcoming developmental events are transcribed. Many early genes have been characterized and placed into gene networks, but how they come to be activated at the proper time, in the proper order, and in a robust manner is unclear. In the last grant period, it was revealed that the Drosophila embryo uses a simple strategy to collectively and selectively activate genes - the transcription factor Zelda (Zld) recognizes and binds a specific sequence motif (CAGGTA), and subsequently integrates gene networks into a system of coherent and incoherent feed-forward loops. In doing so, Zld drives the major reprogramming event that occurs during the maternal-to-zygotic transition (MZT), where the embryo takes over control of development from the mother. This is the first demonstration of such a regulator in any organism, thus, Zld provides a paradigm for the global coordination of gene networks in early development. Zld resembles a special class of transcription factors called pioneer factors, which are the first to engage target genes, providing competence for future activation when developmental signals come along. The goal of this proposal is to reveal the underlying mechanisms by which Zld functions to regulate zygotic genome activation (ZGA) and to provide robust temporal control to the activities of the key developmental regulators. Zld protein is initially at low levels, rises in concentration by one hour, coincident with ZGA, then decreases in the third hour. The regulation of Zld protein dynamics and how Zld times the on-off state of early genes is unclear. The hypothesis that a threshold level of Zld triggers genome activation will be tested by altering Zld concentrations and monitoring target gene activation. Whether Zld itself is regulated will be assessed, with focus on a potential role of the zld 3' UTR. The idea that Zld binding leads to local remodeling of the chromatin landscape, thus increasing accessibility of other factors, leading to increased "expressivity" of target genes will be tested. Global changes in chromatin states at enhancers and transcription start sites before ZGA when the genome is inactive, after ZGA when the early set of zygotic genes are transcribed, and later when many early genes are turned off and others are activated will be examined. Importantly, comparing chromatin states in wild-type and zld mutants will reveal if Zld mediates epigenetic changes during the MZT, and if certain chromatin marks prepare genes for future transcriptional activation/repression. Genetic, genomic, and biochemical approaches will be used to test these hypotheses. Key reagents include zld mutants, zld rescue transgenes to alter Zld levels, and transcriptional reporter transgenes to assay Zld target- gene responses to changes in Zld binding sites. The experimental approaches will lead to a greater understanding of zygotic genome reprogramming from a quiescent state to a robustly active state in early development.

描述（由申请人提供）：关于早期发展的许多知识尚不清楚。在受精后的某个时刻，二合基因组被激活，并转录即将发生的发育事件所必需的基因。许多早期基因已被表征并置于基因网络中，但是如何在适当的时间，适当的顺序和以鲁棒的方式激活它们的方式尚不清楚。在上一个赠款期间，据透露，果蝇胚胎使用一种简单的策略来共同和选择性地激活基因 - 转录因子Zelda（ZLD）识别并结合了特定的序列基序（CAGGTA），然后将基因网络集成到相干和不稳定的Feforhard Feforward Forborward loops的系统中。在此过程中，ZLD驱动了在母亲到杂种过渡期间发生的主要重编程事件（MZT），胚胎接管了母亲的发展。这是任何生物体中这种调节剂的首次演示，因此，ZLD为早期发展中基因网络的全球协调提供了范式。 ZLD类似于称为先锋因素的特殊类转录因子，这些因素是第一个参与目标基因的因素，在出现发展信号时为未来激活提供了能力。该提案的目的是揭示ZLD功能调节合子基因组激活（ZGA）的基本机制，并为关键发育调节剂的活性提供强大的时间控制。 ZLD蛋白最初处于低水平，浓度升高一小时，与ZGA一致，然后减少 第三个小时。 ZLD蛋白质动力学的调节以及ZLD如何在早期基因的开关状态下次数尚不清楚。 ZLD阈值水平触发基因组激活的假设将通过改变ZLD浓度和监测靶基因激活来测试。是否会评估ZLD本身，重点是ZLD 3'UTR的潜在作用。 ZLD结合会导致染色质景观的局部重塑，从而增加其他因素的可及性，从而导致靶基因的“表现力”提高。在基因组不活跃时，在ZGA之前的染色质状态和转录启动位点的全球变化，在ZGA之后，在早期的合子基因被转录时，然后将检查许多早期基因并将其激活的其他早期基因进行检查。重要的是，比较野生型和ZLD突变体中的染色质状态将揭示ZLD是否介导MZT期间的表观遗传变化，以及某些染色质标记是否为未来的转录激活/抑制准备基因。遗传，基因组和生化方法将用于检验这些假设。关键试剂包括ZLD突变体，ZLD拯救转基因以改变ZLD水平，转录报告基因转基因，以测定ZLD靶基因对ZLD结合位点变化的响应。实验方法将使从静态状态到早期发育中从静止状态到坚固活性状态的二吻性基因组对重编程的重新理解。