Cell fate to mechanical cellular properties: coordinated cell behaviours during Drosophila gastrulation

在生物体的发育过程中，细胞通过多种方式改变形状，为组织和器官的形成做出贡献。在动物中创造复杂形状的一种常见方法是将二维扁平上皮折叠成三维高阶结构。一个研究得特别充分的例子是“腹沟”的形成，这是果蝇胚胎早期发育过程中的第一个形态发生事件。我们知道的基因和机制，触发细胞的收缩，形成沟壑，这导致一个凹痕在上皮。对于沟外的细胞如何参与这一过程，从而使其成为可能，我们所知甚少。我们已经发现了胚胎中不同细胞群的机械特性的差异，并发现这些差异对沟的正确形成很重要。但我们不了解分子或生化基础。这个项目的目的就是要发现它。胚胎中细胞的力学特性是由每个细胞中的蛋白质决定的。对许多蛋白质来说，重要的不仅是存在与否（或精确水平），还有它们的活动状态，而这些状态又由其他蛋白质控制。如果两个假设的细胞除了它们的机械特性外在所有方面都是相同的，那么它们应该只有，或者至少主要是在那些控制机械特性的蛋白质活动上有所不同。这是我们的建议所基于的假设，我们的目标就是要识别这些蛋白质。早期果蝇胚胎是一个理想的系统，因为直到原肠胚形成时期，胚胎的6000个细胞都含有或多或少相同的蛋白质。我们将找到我们感兴趣的蛋白质，通过确定沿背-腹轴的三个细胞群的全部蛋白质，这些细胞群代表了参与沟槽形成的细胞群。然后我们将比较这些集合，以及每个集合中蛋白质活性状态的标记。并不是所有我们可能发现的不同群体之间的蛋白质都必然直接参与细胞力学。我们将根据进一步的假设选择蛋白质进行详细的研究，例如，细胞骨架和细胞粘附复合物的成分在决定细胞的机械特性方面起着最重要的作用。然后将使用经典和新颖的遗传方法来操纵胚胎中的这些蛋白质，并评估这些操作的结果，作为测试我们假设的一种手段。

During the development of an organism, cells change their shapes in many ways to contribute to the creation of tissues and organs. A common way of creating complex shapes in animals is the folding of two-dimensional, flat epithelia into three-dimensional higher order structures. A particularly well studied example for this is the formation of the ‘ventral furrow’, the first morphogenetic event during the early development of the Drosophila embryo. We know the genes and the mechanisms that trigger a contraction of the cells that form the furrow, which results to an indentation in the epithelium. Much less is known about how cells outside the furrow participate in the process, and thereby enable it. We have discovered differences in the mechanical properties of different cell populations in the embryo, and found that these differences matter for the proper formation of the furrow. But we do not understand the molecular or biochemical basis. The aim of this project is to discover it.The mechanical properties of the cells in the embryo are determined by the proteins in each cell. For many proteins it is not only the presence or absence (or precise level) that may matter, but also their state of activity, which is in turn controlled by other proteins. If two hypothetical cells that are identical in all respects apart from their mechanical properties, they should differ only, or at least mainly, in those protein activities that govern mechanical properties. This is the assumption on which our proposal is based, and it is these proteins that we aim to identify. The early Drosophila embryo is an ideal system for this because up to the period of gastrulation, the 6000 cells of the embryo contain more or less identical sets of proteins. We will find the proteins that are of interest to us by determining the entire set of proteins in each of three cell populations along the dorso-ventral axis that represent the populations participating in furrow formation. We will then compare these sets, as well as markers for the state of activity of the proteins in each set. Not all of the proteins we may find that differ between the populations will necessarily be directly involved in cell mechanics. We will select proteins for detailed study based on further assumptions, for example that components of the cytoskeleton and cell adhesion complexes play the most important roles in determining mechanical cell properties. Classic and novel genetic methods will then be used to manipulate these proteins in the embryo, and assess they outcomes of these manipulations, as a means of testing our hypotheses.