Mechanistic roles of the basement membrane mechanics in cellular morphodynamics and tissue patterning of the pre-gastrulating embryo

项目概要/摘要 在早期胚胎发生过程中建立适当的组织水平结构和模式对于一个完整的细胞来说是至关重要的。 成功怀孕在受精后的前2-3周内，人类胚胎的死亡率很高 是早期妊娠丢失的主要原因，但基本的细胞，分子和机械变化仍然存在 定义不好。在早期植入后哺乳动物胚胎发生期间，胚外上皮层， 内脏内胚层，起着至关重要的作用，在破腹事件，指定前， 上胚层的后部图案。具体来说，内脏内胚层细胞的一个子集，前内脏 内胚层向未来前后轴的一端迁移以形成外胚层。最近的工作 我们实验室的研究表明，胚胎基底膜在对称性破缺中起着至关重要的作用， 为原肠胚形成奠定基础的形态发生。然而，细胞外机制如何调节 集体细胞动力学和指示细胞身份以形成模式仍然是未知的。 在这里，我们建议确定胚胎基底膜如何协调集体细胞 行为，并促进模式形成的前后规范。一是全面摸底 整个内脏内胚层的细胞行为与成像方法和定义的作用， 前内脏内胚层膜通过干细胞衍生胚胎中的遗传扰动迁移 就像在自然胚胎中一样。接下来，我们将绘制基底膜力学图， 应用单细胞转录组学方法生成原肠胚形成前胚胎的原位细胞命运图。 我们将从功能上测试基底膜力学如何通过关联基因来调节细胞特性。 表达谱与基底膜结构，并验证与基底膜- 扰乱胚胎。最后，我们将实施多尺度数学模型，将细胞身份和 细胞动力学与基底膜力学，以揭示模式形成的机制。 总的来说，这些实验将揭示胚胎外环境在定义细胞中的功能作用。 原肠胚形成前胚胎的身份。这些发现将为我未来的目标中的后续研究提供信息， 基底膜和胚外组织在拓扑结构不同的胚胎中的保守作用 在人类中看到的。在我的奖学金期间的培训将扩大我的技能，研究更复杂的 哺乳动物的生物学和扩大我的知识在发育生物学的新方面。研究 加州理工学院的环境将进一步促进跨学科的合作，使 开发新的方法来研究早期哺乳动物胚胎发生。

Project Summary/Abstract Establishing proper tissue-level architecture and patterning during early embryogenesis is crucial for a successful pregnancy. A high rate of mortality seen in human embryos during the first 2-3 weeks post-fertilization is a major cause of early pregnancy loss, yet the essential cellular, molecular, and mechanical changes remain poorly defined. During early post-implantation mammalian embryogenesis, an extra-embryonic epithelial layer, the visceral endoderm, plays an essential role in the symmetry-breaking event that specifies the anterior- posterior patterning of the epiblast. Specifically, a subset of the visceral endoderm cells, the anterior visceral endoderm, migrates toward one end of the future anterior-posterior axis to pattern the epiblast. Recent work from our lab reveals that the embryonic basement membrane plays an essential role in symmetry breaking and morphogenesis that sets the stage for gastrulation. However, how the extracellular mechanics modulates the collective cellular dynamics and instructs cell identities for pattern formation remains not known. Here we propose to determine how the embryonic basement membrane coordinates the collective cell behaviors and facilitates anterior-posterior specification for pattern formation. First, we will comprehensively map the cell behaviors of the entire visceral endoderm with imaging approaches and define the role of the basement membrane in anterior visceral endoderm migration through genetic perturbations in stem cell-derived embryo- like structures as well as in the natural embryos. Next, we will map the basement membrane mechanics and apply a single-cell transcriptomics approach to generate in situ cell fate maps of the pre-gastrulating embryos. We will functionally test how the basement membrane mechanics regulate cell identities by correlating the gene expression profiles with basement membrane architecture and validate the findings with basement membrane- perturbed embryos. Finally, we will implement multi-scale mathematical models that integrate cell identities and cell dynamics with the basement membrane mechanics to uncover mechanisms of pattern formation. Overall, these experiments will unveil functional roles of the extraembryonic environment in defining the cell identities of the pre-gastrulation embryos. These findings will inform subsequent studies in my future goals on the conserved roles of the basement membrane and the extraembryonic tissues in topologically distinct embryos seen in human. Training during my fellowship period will expand my skillsets toward studying the more complex biology of mammals and broaden my knowledge on new aspects of developmental biology. The research environment at California Institute of Technology will further foster interdisciplinary collaborations that allow the development of novel approaches to investigate early mammalian embryogenesis.