Regulation of zygotic genome activation by Zelda

Zelda 对合子基因组激活的调控

基本信息

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
项目类别：
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&apos 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

项目摘要

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，还有很多不为人理解的地方。受精后的某个时刻，合子基因组被激活，即将到来的发育事件所需的基因被转录。许多早期基因已被表征并放入基因网络中，但它们如何在适当的时间、以适当的顺序、以稳健的方式被激活尚不清楚。在上一次资助期间，研究人员发现果蝇胚胎使用一种简单的策略来集体选择性地激活基因——转录因子Zelda（Zld）识别并结合特定的序列基序（CAGGTA），随后将基因网络整合到一个系统中相干和非相干前馈环路。在此过程中，Zld 驱动了母体向合子转变 (MZT) 期间发生的主要重编程事件，其中胚胎从母亲手中接管了发育的控制权。这是在任何生物体中首次证明这种调节器，因此，Zld 为早期发育中基因网络的全局协调提供了范例。 Zld 类似于一类特殊的转录因子，称为先锋因子，它是第一个与靶基因结合的因子，为未来发育信号出现时的激活提供能力。该提案的目的是揭示 Zld 调节合子基因组激活 (ZGA) 的基本机制，并为关键发育调节因子的活动提供强大的时间控制。 Zld 蛋白最初处于低水平，一小时浓度上升，与 ZGA 一致，然后浓度下降第三个小时。 Zld 蛋白动力学的调节以及 Zld 如何控制早期基因的开关状态尚不清楚。 Zld 的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。将评估 Zld 本身是否受到监管，重点是 zld 3' UTR 的潜在作用。 Zld 结合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“表达性”增加，这一想法将得到测试。将检查ZGA之前（当基因组不活跃时）、ZGA之后（当早期合子基因组被转录时）以及后来当许多早期基因被关闭而其他基因被激活时，增强子和转录起始位点的染色质状态的整体变化。重要的是，比较野生型和 zld 突变体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。遗传学、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、用于改变Zld水平的zld拯救转基因，以及用于测定Zld靶基因对Zld结合位点变化的反应的转录报告基因转基因。这些实验方法将有助于更好地理解早期发育中合子基因组从静止状态到稳健活跃状态的重编程。