Transcriptome reprogramming in the early embryo

在发育早期，高度协调的母体到受精卵的转变将胚胎重新编程为 多能的细胞特性，能够在发育中的有机体中产生所有后续的细胞类型。多么 细胞被诱导为多能性仍然知之甚少，但却有着巨大的影响，不仅仅是 了解基本的发育和基因调控过程，也用于疾病建模和 治疗。长期目标是破译脊椎动物之间保守的机制和原则， 引导多能诱导。为了开始解决这个问题，这项提议旨在阐明 提供给卵子的多能性因子激活了模型中胚胎基因组的第一批基因 脊椎动物斑马鱼。斑马鱼产生大量外部发育的胚胎，并表达许多关键 与人类保守的多能性调节器，使它们成为理想的实验系统 发现诱导脊椎动物多能性的新调控范例。这项建议有三个主要内容 目标。首先，我们将破译胚胎基因激活的特异性背后的调控逻辑。 母体多能性因子作用于转录静止的胚胎基因组，最初只激活一个 几百个基因，几个小时后数千个基因被激活。尖端技术将是 用于在比以前更早的发育阶段绘制全基因组范围内的多能性因子结合图 已经侧写过了。结合模式将在较早和较晚激活的基因附近进行比较，以及 他们各自的基因调控序列的区别属性将被提取。第二，小说 胚胎基因组激活的调控因素将通过整合多个基因组数据来源来推断。 这些因素将使用创新的功能丧失战略进行评估，以衡量它们对 胚胎重编程和多能性。第三，这项提案将揭示转录后机制 调节母体多能性因素本身。将使用生化和遗传方法 发现结合母体mRNA的因素对它们的表达产生积极或消极的影响，并反过来发挥作用 对多能性诱导进行精确的时间控制。总之，这些分析将进一步阐明该基因。 早期脊椎动物胚胎的调节逻辑，并提供了对如何多能性的更深层次的理解 身份是被诱导出来的。

Early in development, a highly coordinated maternal-to-zygotic transition “reprograms” the embryo to a pluripotent cellular identity, capable of giving rise to all subsequent cell types in the developing organism. How cells are induced to pluripotency is still poorly understood, and yet has enormous implications, not only for understanding fundamental developmental and gene regulatory processes, but also for disease modeling and therapies. The long-term goal is to decipher mechanisms and principles conserved across vertebrates that guide pluripotency induction. To begin to address this question, this proposal aims to elucidate how pluripotency factors provided to the egg activate the first genes from the embryonic genome in the model vertebrate zebrafish. Zebrafish produce large clutches of externally developing embryos and express many key regulators of pluripotency that are conserved with humans, making them an ideal experimental system to discover novel regulatory paradigms that induce vertebrate pluripotency. This proposal has three primary goals. First, the regulatory logic underlying the specificity of embryonic gene activation will be deciphered. Maternal pluripotency factors act on a transcriptionally quiescent embryonic genome to initially activate only a few hundred genes, prior to the activation of thousands of genes hours later. Cutting-edge techniques will be used to map pluripotency factor binding genome wide, at earlier developmental stages than have previously been profiled. Binding patterns will be compared in the vicinity of early- versus later activated genes, and distinguishing properties of their respective gene regulatory sequences will be extracted. Second, novel regulators of embryonic genome activation will be deduced by integrating multiple sources of genomics data. These factors will be evaluated using innovative loss-of-function strategies to measure their contributions to embryonic reprogramming and pluripotency. Third, this proposal will uncover post-transcriptional mechanisms that regulate the maternal pluripotency factors themselves. Biochemical and genetic approaches will be used to discover factors that bind maternal mRNA to positively or negatively affect their expression, and in turn exert precise temporal control over pluripotency induction. Together, these analyses will further elucidate the gene regulatory logic of the early vertebrate embryo and provide a deeper understanding of how pluripotent identities are induced.