Biomechanics of gastrulation in zebrafish

 描述(申请人提供)：体轴的形成和器官的形态发生在很大程度上取决于细胞集体迁移到胚泡中特定位置的能力。虽然已知有许多不同的分子通路，如Nodal、BMP和Wnt，通过控制命运决定和基因表达来控制胚胎发育，但最近已表明，另一类信号，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，细胞的运动及其变化是由不同的细胞力引起的，这种差异在很大程度上是由细胞肌球蛋白活性和细胞-细胞黏附在分子水平上控制的。然而，信号事件控制支持细胞运动的细胞力的内源分布的机制尚不清楚，主要是因为缺乏允许在体内测量细胞力的技术。PI最近开发了新型的力传感器(生物兼容的油微滴)，可以直接测量活的胚胎组织中细胞产生的机械力。这项独特的技术将用于与Alexander Schier博士合作研究斑马鱼原肠形成的生物力学。Alexander Schier博士的实验室最近发现了一种分泌肽，它通过APJ/Apelin受体发出信号，促进斑马鱼原肠形成过程中中胚层细胞的运动。重要的是，通过APJ/Apelin受体的信号已被证明在不同组织中影响细胞迁移和生物力学。鉴于这些发现，我们假设幼儿通过Apelin/APJ受体发出的信号调节中胚层细胞之间的作用力，从而影响它们的迁移。为了验证这一假说，我们计划(1)在野生型和幼儿信号受损的胚胎中，测量腹侧和背侧中胚层侵入和迁移过程中细胞产生的机械力，以及(2)建立这些力是如何在体内通过acto-myosin收缩和细胞黏附水平的变化来调节的，以及描述幼儿信号如何调节这些分子过程来影响细胞间力。这项探索性研究有望揭示幼儿信号如何影响中内胚层细胞在内向和迁移过程中产生的差别力，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来引导细胞迁移。

 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.