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

项目摘要/摘要 在早期胚胎发育期间建立适当的组织水平的架构和模式对于 成功怀孕。受精后2-3周内人类胚胎的高死亡率 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。 定义不明确。在植入后哺乳动物胚胎发生的早期，胚胎外上皮层， 内脏内胚层在对称性破坏事件中起着至关重要的作用，对称性破坏事件规定了前-内胚层 上胚层的后部花纹。具体地说，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，形成上胚层。近期工作 来自我们实验室的研究表明，胚胎基底膜在对称破坏和 为原肠形成奠定基础的形态发生。然而，细胞外机制是如何调节 集体细胞动力学和指示细胞身份以形成图案仍不清楚。 在这里，我们建议确定胚胎基底膜如何协调集体细胞。 行为，并促进图案形成的前后部规范。首先，我们将全面测绘 用成像方法观察整个内脏内胚层的细胞行为并确定基底的作用 干细胞来源的胚胎通过遗传扰动在前内脏内胚层迁移中的膜- 类似的结构以及在自然胚胎中。接下来，我们将绘制基底膜的力学和 应用单细胞转录学方法生成原肠前期胚胎的原位细胞命运图。 我们将从功能上测试基底膜机制如何通过关联基因来调节细胞特性。 基底膜结构的表达谱，并用基底膜验证研究结果。 受惊的胚胎。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。 总体而言，这些实验将揭示胚胎外环境在定义细胞方面的功能作用 原肠前期胚胎的特征。这些发现将为我未来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 在人类身上见过。我在团契期间的训练将扩展我的技能，使我能够学习更复杂的知识 研究哺乳动物生物学，拓宽我对发育生物学新方面的认识。这项研究 加州理工学院的环境将进一步促进跨学科合作，使 研究哺乳动物早期胚胎发生的新方法的发展。

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.