小鼠早期胚胎表观遗传图谱的建立

Early embryo development of vertebrates is a strictly regulated cell programming process. During mouse embryo gastrulation stage, embryonic cells in specific locations are modulated by extrinsic signals, intrinsic factors, and epigenetic regulation during cell movements and differentiation, and these cells are developed into an embryo with anterior-posterior and proximal-distal characteristics. Consequently, the gastrulated embryo is specified into ectoderm, mesoderm, and endoderm, with specific gene expression patterns and cell fates. In our previous study, we have established the whole transcriptome of early mouse embryo through single cell sequencing-based laser microdissection technology. Epigenetic regulation is involved cell linage establishment and fate decision, whereas it remains unknown how epigenetic regulation participates in the establishment of embryonic patterning during gastrulation. Mid-gastrula mouse embryos (E7.0) were used in this project, and these embryos were dissected into anterior, posterior, and extraembryonic ectoderm part. Subsequently, the three parts were subjected to microChIP-seq analysis separately to determine the histone modification and DNA methylome, establishing the whole epigenome in early mouse embryo. Finally, we will explore the functions of epigenetic regulation in embryonic patterning and cell programming in mouse embryo gastrulation stage.

哺乳动物早期胚胎发育是一个受到严谨精细调控的细胞编程过程。在小鼠胚胎发育早期的原肠运动时期，胚胎各个特定位置的细胞在迁移和分化中，受到外源信号、内源因子及表观遗传调控的综合作用，由多能性的上胚层干细胞发育为不同发育命运的外胚层、中胚层、内胚层。表观遗传调控是参与细胞谱系建立和细胞命运决定的重要调控方式，但是目前表观遗传调控是如何参与小鼠胚胎原肠运动时期特异性基因表达模式的建立鲜有报道。本实验室前期工作通过基于单细胞测序的激光显微切割方法，建立了小鼠原肠运动中期全胚胎的转录组图谱。在此基础上，本项目以小鼠胚胎原肠运动中期（E7.0）的胚胎为研究材料，将其切割为前端（A）、后端(P)和胚外外胚层(EXE)三部分，通过微量ChIP-seq技术，分析组蛋白修饰和DNA甲基化在胚胎各部分中的分布，建立小鼠早期胚胎的表观遗传修饰全景图谱，以求揭示表观遗传调控网络在早期胚胎模式建成和细胞编程中的功能。

本项目计划通过建立针对少量细胞的表观遗传学研究方法探索小鼠原肠运动时期胚胎模式建成过程中的表观遗传学机制。完成体外小鼠上胚层干细胞 (EpiSC) 培养过程中细胞异质性情况的研究，阐明了不同类群EpiSC 细胞的分化潜能差异；系统概述了小鼠胚胎干细胞神经分化过程中的表观遗传学调控机制；完成小鼠原肠运动时期胚层模式建成的转录组表达图谱的建立，完成小鼠原肠运动时期区域特异性的表观遗传学图谱的构建，阐明了小鼠原肠运动时期上胚层细胞向三胚层命运决定过程中的表观遗传学机制及功能调控元件活性的变化机制，揭示了小鼠早期胚胎发育过程中的表观遗传调控网络。项目基本按照研究计划执行，完成项目预期目标。