Temporal program for cell fate specification in the mouse embryo

小鼠胚胎细胞命运规范的时间程序

• 批准号: 10046014
• 负责人: Magdalena Zernicka-Goetz
• 金额: $ 50.4万
• 依托单位: CALIFORNIA INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10046014
• 关键词: Actins; Actomyosin; Affect; Apical; Assisted Reproductive Technology; Behavior Control; Cell Cycle; Cells; Complex; Cytoskeleton; Data; Defect; Development; Developmental Biology; Dose; Embryo; Embryonic Development; Ensure; Event; Experimental Models; Fetus; GATA3 gene; Genetic Transcription; Goals; Human; Imaging Techniques; Inner Cell Mass; Lead; Light; Link; Mammals; Mediating; Medical; Methods; Modeling; Morphogenesis; Mus; Myosin ATPase; Nuclear Translocation; Pharmacology; Placenta; Pregnancy loss; Process; Property; Proteins; Regenerative Medicine; Reproduction; Role; Signal Transduction; Testing; Time; Tissues; To specify; Totipotency; Totipotent; Up-Regulation; Work; base; blastocyst; cell fate specification; cell type; experimental study; implantation; insight; mouse development; natural Blastocyst Implantation; novel; optogenetics; pluripotency; polarized cell; pregnancy failure; pregnancy prevention; preimplantation; progenitor; programs; protein complex; rho; segregation; self organization; stem cell biology; transcription factor; zygote

SUMMARY. The first cell fate decision in mammals transforms a totipotent embryo comprising identical cells into two cell types: outer trophectoderm cells, which will give rise to the placenta, and inner pluripotent cells, which will give rise to the fetus. This decision depends on cell polarization. Although we understand how cell polarization connects to downstream signaling to specify the two cell types, the mechanisms that act earlier, to ensure cell polarization and its specific developmental timing, remain entirely unknown. To identify this mechanism, we first need to identify the upstream regulators, which have been elusive – until now. We recently found that two zygotically expressed transcription factors, Tfap2c and Tead4, together with Rho-mediated actomyosin activity, are essential and sufficient to trigger de novo cell polarization. These results provide us with an unprecedented opportunity to determine the mechanism that triggers the specific developmental timing of embryo polarization in early mammalian development. The objective of this proposal is to reveal the principles of self-organization that lead to de novo polarization and consequently the first cell fate specification in the key model mammalian embryo, the mouse embryo. Our central hypothesis is that zygotic transcription cooperates with the cytoskeleton to polarize cells and drive the first cell fate determination. We will test this hypothesis via the following Specific Aims: Aim 1: To determine what regulates timing of embryo polarization. We hypothesize that the timing of embryo polarization is controlled by Tfap2c and Tead4. We will alter the dose and developmental stage of Tfap2c and Tead4 expression and examine the effects on their downstream targets and the timing of embryo polarization. Aim 2: To determine how the apical domain becomes established. We hypothesize that Tfap2c and Tead4 regulate apical domain formation by modulating the actomyosin cytoskeleton, which in turn controls the conjugation of Par complex clusters. We will use advanced imaging techniques and pharmacological and optogenetic methods to determine the role of the actomyosin cytoskeleton in regulating apical domain formation and the dynamics of the Par complex during polarization. We will also examine how Tfap2c and Tead4 control the behavior of the actomyosin cytoskeleton and the organization of apical proteins into clusters to form the apical domain. Aim 3: To determine how altered timing of polarization affects embryo development. Embryo polarization always happens at the late 8-cell stage, just before the first cell fate decision, suggesting that the invariant timing of this polarization is critical for subsequent developmental progression. We will determine if accelerating the timing of embryo polarization by one cell cycle at the pre- implantation stage affects subsequent development, specifically cell fate and blastocyst formation before implantation and embryo morphogenesis post-implantation. We expect to discover the triggers and mechanisms that regulate the precise timing of cell polarization in the mouse embryo. Our work will likely have major medical relevance, as it will shed light on the causes of early developmental defects and pregnancy loss in humans.

概括。哺乳动物中的第一个细胞命运决定将包含相同细胞的全能胚胎转化为 两种细胞类型：外部滋养外胚层细胞（将产生胎盘）和内部多能细胞（将产生胎盘） 会生出胎儿。这个决定取决于细胞极化。尽管我们了解细胞如何 极化连接到下游信号传导以指定两种细胞类型，即较早起作用的机制，以 确保细胞极化及其具体发育时间仍然完全未知。为了识别这一点 为了建立机制，我们首先需要确定上游监管机构，而迄今为止，这些监管机构一直难以捉摸。我们最近 发现两个合子表达的转录因子 Tfap2c 和 Tead4 以及 Rho 介导的转录因子 肌动球蛋白活性对于触发细胞从头极化是必要且足以触发的。这些结果为我们提供了 这是一个前所未有的机会来确定触发特定发育时间的机制 早期哺乳动物发育中的胚胎极化。该提案的目的是揭示原则 导致从头极化的自组织，从而导致关键的第一个细胞命运规范 模型哺乳动物胚胎，小鼠胚胎。我们的中心假设是合子转录合作 与细胞骨架一起极化细胞并驱动第一个细胞命运的决定。我们将通过以下方式检验这个假设 具体目标如下： 目标 1：确定胚胎极化时间的调节因素。我们 假设胚胎极化的时间由 Tfap2c 和 Tead4 控制。我们将改变剂量并 Tfap2c 和 Tead4 表达的发育阶段并检查对其下游靶标的影响 胚胎极化的时间。目标 2：确定顶端域如何建立。我们 假设 Tfap2c 和 Tead4 通过调节肌动球蛋白来调节顶端结构域的形成 细胞骨架，进而控制 Par 复合体簇的缀合。我们将使用先进的成像技术 确定肌动球蛋白细胞骨架作用的技术、药理学和光遗传学方法 调节顶端域的形成和极化过程中 Par 复合体的动力学。我们还将 检查 Tfap2c 和 Tead4 如何控制肌动球蛋白细胞骨架的行为和组织 顶端蛋白质成簇形成顶端结构域。目标 3：确定极化时间如何改变 影响胚胎发育。胚胎极化总是发生在 8 细胞阶段晚期，就在第一个细胞阶段之前 细胞命运决定，表明这种极化的不变时间对于后续发育至关重要 进展。我们将确定胚胎极化的时间是否加速了一个细胞周期。 着床阶段影响随后的发育，特别是之前的细胞命运和囊胚形成 着床和着床后胚胎形态发生。我们期望发现触发因素和机制 调节小鼠胚胎中细胞极化的精确时间。我们的工作可能会涉及重大的医学 相关性，因为它将揭示人类早期发育缺陷和流产的原因。