Biomechanics of gastrulation in zebrafish

 描述（由申请方提供）：体轴形成和器官形态发生主要取决于细胞集体迁移到胚胎中特定位置的能力。虽然许多不同的分子途径，如Nodal，BMP和Wnt，已知通过控制命运决定和基因表达来管理胚胎发育，但最近已证明，不同类别的信号，包括Wnt/PCP和Toddler，通过调节细胞运动在形态发生过程中发挥关键作用。从生物物理学的角度来看，细胞运动及其变化是由不同的细胞力引起的，这些细胞力在很大程度上在分子水平上由肌动球蛋白活性和细胞-细胞粘附控制。然而，信号事件控制细胞运动的细胞力的内源性分布的机制是未知的，主要是因为缺乏允许测量体内细胞力的技术。PI最近开发了新型力传感器（生物相容性油微滴），允许直接测量活胚胎组织内细胞产生的机械力。这项独特的技术将用于该项目，与亚历山大希耶博士合作研究斑马鱼原肠胚形成的生物力学，他的实验室最近发现了Toddler，一种分泌肽，通过APJ/Apelin受体发出信号，促进斑马鱼原肠胚形成期间的中内胚层细胞运动。重要的是，通过APJ/Apelin受体的信号传导先前已被证明会影响不同组织中的细胞迁移和生物力学。鉴于这些发现，我们假设，幼儿信号通过爱帕琳/APJ受体调节中内胚层细胞之间的力量，从而影响他们的迁移。为了检验这一假设，我们计划（1）在野生型以及幼儿信号传导受损的胚胎中测量腹侧和背侧中内胚层侵入和迁移期间细胞产生的机械力，以及（2）确定这些力如何通过肌动蛋白-肌球蛋白收缩性和细胞粘附水平的变化在体内调节，以及表征如何幼儿信号调节这些分子过程，影响细胞间的力量。这项探索性研究有望揭示幼儿信号传导如何影响中内胚层细胞在侵入和迁移过程中产生的差异力，首次将控制形态发生运动的分子途径与最终驱动细胞迁移的生物力学特性联系起来。我们相信这项研究将提供一个框架，以了解信号事件如何通过组织和细胞生物力学的时空控制引导细胞迁移。

 DESCRIPTION (provided by applicant): Body axis formation and organ morphogenesis depend critically on the ability of cells to migrate collectively to specific locations in the embro. While a number of different molecular pathways, such as Nodal, BMP, and Wnt, are known to govern embryonic development by controlling fate determination and gene expression, a different class of signals, including Wnt/PCP and Toddler, has been recently shown to play a crucial role during morphogenesis by regulating cellular movements. From a biophysics perspective, cellular movements, and changes of thereof, are caused by differential cellular forces, which are largely controlled at the molecular level by acto-myosin activity and cell-cell adhesion. However, the mechanisms by which signaling events control the endogenous distribution of cellular forces underlying cellular movements are unknown, mainly because of a lack of technologies allowing the measurement of cellular forces in vivo. The PI has recently developed novel force transducers (biocompatible oil microdroplets) that allow direct measurements of cell-generated mechanical forces within living embryonic tissues. This unique technology will be used in this project to study the biomechanics of zebrafish gastrulation in collaboration with Dr. Alexander Schier, whose lab recently discovered Toddler, a secreted peptide that signals through APJ/Apelin receptors and promotes mesendodermal cell movements during zebrafish gastrulation. Importantly, signaling through APJ/Apelin receptors has previously been shown to affect cell migration and biomechanics in different tissues. Given these findings, we hypothesize that Toddler signaling via Apelin/APJ receptors regulates the forces between mesendodermal cells, thereby affecting their migration. In order to test this hypothesis, we plan to (1) measure the cell- generated mechanical forces during ventral and dorsal mesendodermal ingression and migration, in wild type as well as in embryos with impaired Toddler signaling, and (2) establish how these forces are modulated in vivo via changes in acto-myosin contractility and cell adhesion levels, as well as characterize how Toddler signaling regulates these molecular processes to affect intercellular forces. This exploratory research promises to reveal how Toddler signaling affects the differential forces generated by mesendodermal cells during ingression and migration, linking for the first time a molecular pathway controlling morphogenetic movements to the biomechanical properties that ultimately drive cell migration. We believe this study will provide a framework to understand how signaling events guide cell migrations via the spatiotemporal control of tissue and cell biomechanics.