Morphogenesis of the paraxial mesoderm in mice

描述（由申请人提供）：该项目的主要目的是使用分子、胚胎学、遗传学和光学技术的组合来了解指导小鼠胚胎中胚层形态发生的细胞和分子事件。我们的中心假设是，Wnt3a是一个关键的信号分子中胚层规范和图案的几个方面必不可少的。在分离天然发荧光的蛋白质方面的最新进展以及光学显微镜技术的改进为直接在胚胎内研究细胞和分子事件的体内成像提供了前所未有的机会。光学成像的应用结合一个新的面板的转基因报告基因表达小鼠，我们已经产生了代表一个独特的平台，用于获取定量信息的细胞行为和细胞的命运在体内。我们将利用这些试剂来研究野生型胚胎中近轴中胚层的形态发生所不可或缺的动态细胞行为，以及破坏这一过程的Wnt3a突变体的等位基因系列。本研究的具体目的是：（1）利用活体成像技术研究小鼠胚胎原条内中胚层发生过程中的细胞行为。(2)利用活体成像技术来确定中胚层前体细胞的行为。(3)确定近轴中胚层祖细胞是否存在于小鼠胚胎的原条中。将通过使用Wnt3a突变体的等位基因系列来测试Wnt3a在这些过程中介导的信号传导的作用。这项工作将阐明中胚层形成扰动导致的细胞缺陷，并将影响我们对人类出生缺陷影响骨骼和肌肉组织的发病机制的理解。此外，我们研究中胚层祖细胞的工作将有助于中胚层干细胞的分离，确定其内在的细胞行为，其分子特征，并最终将其定向分化用于基于细胞的治疗。

DESCRIPTION (provided by applicant): The broad aim of this project is to use a combination of molecular, embryological, genetic and optical techniques to understand the cellular and molecular events that direct the morphogenesis of mesoderm within the mouse embryo. Our central hypothesis is that Wnt3a is a key signaling molecule essential for several aspects of mesoderm specification and patterning. Recent advances in the isolation of proteins that naturally fluoresce, and the refinement of techniques for optical microscopy offer unprecedented opportunities for in vivo imaging to study cellular and molecular events directly within embryos. The application of optical imaging combined with a novel panel of transgenic reporter expressing mice that we have generated represent a unique platform for acquiring quantitative information on cell behavior and cell fate in vivo. We will exploit these reagents to investigate the dynamic cell behaviors integral to the morphogenesis of the paraxial mesoderm in wild type embryos and an allelic series of Wnt3a mutants that disrupt this process. The Specific Aims of this proposal are: (1) To use in vivo imaging to define the cell behaviors integral to the genesis of mesoderm within the primitive streak of the mouse embryo. (2) To use in vivo imaging to define the cell behaviors integral to the presomitic mesoderm. (3) To establish if paraxial mesoderm progenitor cells reside within the primitive streak of the mouse embryo. A role for signaling mediated by Wnt3a in these processes will be tested through use of the allelic series of Wnt3a mutants. This work will shed light on the cellular defects resulting from perturbations in mesoderm formation and will impact our understanding of the pathogenesis of human birth defects affecting the skeleton and musculature. Furthermore our work investigating mesodermal progenitor cells will contribute information towards the isolation of mesodermal stem cells, the determination of their intrinsic cell behaviors, their molecular signature and ultimately their directed differentiation for use in cell-based therapies.