核小体重塑在果蝇母源向合子转化中的表观调控作用

项目名称： 核小体重塑在果蝇母源向合子转化中的表观调控作用

项目编号： No.31271373

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 生物科学

项目作者： 江赐忠

作者单位： 同济大学

项目金额： 80万元

中文摘要： 果蝇胚胎发育从母源向合子转化(MZT)过程中，由母源成分驱动基因表达过渡到合子基因启动表达，染色质由解聚松散到凝聚形成异染色质。我们据此假设核小体重塑改变染色质构象，是合子基因启动转录的决定因素之一，以及组蛋白修饰参与其中染色质标记的建立。我们绘制了首张全基因组果蝇核小体图谱，并揭示核小体定位在基因转录调控中的作用。在此基础上，本项目以果蝇1-2与3-4小时胚胎(分别代表MZT前后)为实验材料，通过测序与生物信息分析，分别绘制这两时期核小体、组蛋白修饰、RNA Pol II结合图谱，和转录组。分析三者的分布规律、基因表达的变化、三者之间的关联性及调控基因激活与抑制的模式。这些分析将揭示果蝇胚胎发育MZT前后核小体重塑产生的染色质开放与屏蔽构象变化，组蛋白修饰在MZT中的作用，及协同激活合子基因转录的机制。本项目将为研究哺乳动物中由染色质重塑异常造成的发育缺陷的分子机制提供理论依据与方法。

中文关键词： 果蝇；胚胎；母体-合子过渡；核小体；组蛋白修饰

英文摘要： After fertilization, Drosophila zygotic genome is inactive and gene transcription is driven by maternal components. Zygotic transcription is only initiated during maternal-zygotic transition (MZT). Chromatin appears largely decondensed and unstructured during first divistions and forms into domains along the process of MZT, for example, heterochromatin foci. We speculate that nucleosome remodeling changes chromatin configuration,and is likely one of the determinants of zygotic transcription initiation. In addition to this, histone modifications may invovle the establishment of chromatin signaure during MZT. Little is known about this critical question of embryonic development so far. We generated the first map of genome-wide nucleosome positions, and revealed that nucleosomes engaged in RNA Pol II pausing during transcrition. In this proposal, on the basis of our previous study, we plan to collect large amount of 1-2 h and 3-4 h fly embryos (representating before and after MZT, respectively), digest them with MNase to get mononucleosomes. ChIP assays are used to collect H3, H3K4me3, H3K27me3 nucleosomes, and RNA Pol II-bound DNA. Their DNA were sequenced with Solexa Hi-seq, respectively. Bioinformatics approaches are used to predict nucleosomes and RNA Pol II binding sites. The high-resolution maps of H3 wild-ty

英文关键词： Drosophila；embryo；maternal-zygotic transition；nucleosome；histone modification