The Role of NMD in Pre-Implantation Development

NMD 在植入前发育中的作用

• 批准号: 9192257
• 负责人: Jennifer Chousal
• 金额: $ 3.58万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9192257
• 关键词: Accounting; Address; Adult; Affect; Biology; Cell Differentiation process; Cell Lineage; Cells; Complement; Complex; Coupled; Data; Defect; Degradation Pathway; Development; Down-Regulation; ES Cell Line; Embryo; Embryonic Development; Employee Strikes; Endoderm; Equilibrium; Eukaryota; Event; Fibrinogen; Gap Junctions; Gene Expression; Germ Layers; Goals; Heterogeneity; Histocompatibility Testing; Human; Human Cell Line; Human Development; In Vitro; Infertility; Inner Cell Mass; Knockout Mice; Knowledge; Laboratories; Lead; Measures; Mediating; Mesoderm; MicroRNAs; Modeling; Molecular; Mus; Organ; Organism; Pathway interactions; Phylogenetic Analysis; Play; Post-Transcriptional Regulation; Pre-implantation Embryo Development; Proteins; Publications; Publishing; RNA Decay; RNA Degradation; RNA chemical synthesis; Repression; Role; Signal Transduction; Staging; Time; Tissues; Transcript; Transcriptional Regulation; Undifferentiated; Up-Regulation; Work; base; blastocyst; blastomere structure; cell type; embryonic stem cell; fascinate; gain of function; genome-wide; human embryonic stem cell; in vivo; knock-down; mRNA Decay; mouse model; nerve stem cell; neural initiation; preimplantation; relating to nervous system; research study; stem cell differentiation; stem cell fate; stem cell technology; transcriptome sequencing; zygote

ABSTRACT Pathways regulating cell fate decisions during the earliest stages of embryo development are complex and remain poorly understood. Most developmental studies concentrate on transcriptional regulation, and thus fail to take into account the fact the steady-state levels of RNAs are dictated as much by their rate of decay as by their rate of synthesis. This proposal focuses on Nonsense-Mediated RNA Decay (NMD), a highly conserved RNA degradation pathway that selectively degrades specific subsets of transcripts. Loss or knockdown of NMD factors leads to developmental defects in species spanning the phylogenetic scale, including humans. One of the most striking findings is that loss of all but one of the examined NMD factors leads to early embryonic lethality in mice, as well as other higher eukaryotes. To date, there have been no studies examining the underlying mechanism. This application addresses this question using mouse models and normal human cell lines, coupled with genome-wide molecular approaches at the single-cell level. The overarching hypothesis is that NMD degrades specific transcripts to control developmental decisions in the early embryo. Support for this hypothesis comes from previously published studies on neural differentiation from the Wilkinson laboratory, in which they identified NMD-based circuits that maintain the neural stem cell state. Neural differentiation signals trigger the expression of microRNAs that repress NMD, leading to stabilization of pro-neural transcripts and the consequent initiation of neural differentiation. This work led to the hypothesis that NMD also promotes the undifferentiated state in other cell lineages. In support, the Wilkinson laboratory demonstrated that NMD magnitude tends to be high in undifferentiated cells and is downregulated upon differentiation. Furthermore, they showed that NMD magnitude plays a specific role in regulating cell fate decisions of primary germ layers in human embryonic stem cells (hESCs), such that NMD downregulation drives endoderm differentiation, while NMD upregulation augments mesoderm differentiation. In addition, the Wilkinson laboratory recently discovered a factor that likely plays a critical role in controlling NMD magnitude in hESCs and the early embryo. This factor, UPF3A, was previously regarded as a weak NMD factor from artificial tethering experiments, but we recently showed that it acts primarily as a potent NMD repressor through extensive loss- and gain-of-function experiments, both in vitro and in vivo. This suggests the hypothesis that UPF3A serves as a molecular rheostat, thereby controlling differentiation events critical in early embryonic development. In support of this hypothesis, the Wilkinson laboratory showed that loss of UPF3A causes early embryonic lethality, accompanied by morphological defects at the pre-implantation stage. The goals of my proposal are to (i) dissect the specific roles of NMD in early pre-implantation embryo development, (ii) elucidate the role of a NMD repressor identified by the Wilkinson laboratory—UPF3A—in embryogenesis, and (iii) define molecular circuits by which NMD acts in early development using hESCs to model human development.

抽象的 在胚胎发育的高位阶段调节细胞命运决策的途径很复杂，并且 大多数关于转录调节的发展研究，因此也失败了 考虑到tate rNA的事实是由其衰减率所决定的 合成速率。 降解途径，可选择转录本的特定子集。 导致跨越系统发育量表的物种的发育缺陷，最倾向的人之一。 引人注目的发现是，除了检查的NMD因子之一以外的所有损失都导致小鼠的早期胚胎懒惰嗜血杆菌，即 以及迄今为止其他较高的真核生物。 此应用程序使用鼠标模型和正常的人类细胞细胞系解决了一个问题，并与 单细胞水平的全基因组分子方法。 总体假设是，NMD降低了特定的转录本以控制发展中的发展决策 对假设的早期支持来自于公开公开的神经区分 威尔金森（Wilkinson）实验室，他们在其中确定了维持神经干细胞状态的基于NMD的电路。 神经区分信号触发了抑制NMD的microRNA的表达，导致稳定 亲神经的成绩单和神经分化的奉献。 NMD还促进了其他细胞谱系中未分解的状态。 证明NMD磁化体在未分化的细胞中往往很高，并且在 区分。 人类胚胎干细胞（hESC）中原发性胚层的决策，使得NMD下调驱动 内胚层的区分，而NMD上调增加了中胚层的区分。 实验室最近发现了一个因素，该因素可能在控制hESC和hESC和 早期的胚胎。 实验，但我们逐渐证明它主要通过广泛的损失 - 在体外和体内的功能实验都表明，UPF3A的假设是 一个分子风湿病，在早期胚胎发育中控制了差异化事件。 在这一假设中，威尔金森实验室表明，UPF3A的损失会导致拥抱性致死性， 伴随着植入阶段的形态缺陷。 NMD在早期植入前胚胎发育中的特定作用，（ii）阐明了NMD的作用 由威尔金森实验室（UPF3A-胚胎发生）确定的阻遏物，（iii）定义分子电路 NMD使用hESC在早期开发中发挥作用来对人类发展进行建模。