The systems biochemistry of polarized cytoskeletal morphogenesis

活细胞以非随机、极化的方式组织它们的内部，以执行特殊的生物功能。细胞的极性是由质膜、相关蛋白和细胞质分子之间的复杂相互作用引起的。在真核细胞中，对称性在大多数情况下最初是在膜结合分子水平上被破坏的，例如磷脂酰肌醇脂类和Rho-型GTP酶。这些保守的信号中枢通过肌动蛋白细胞骨架协同控制细胞的形态发生和运动。虽然这些紧密相连的系统的许多组成部分已经被定义，但人们对细胞极性和形状变化背后的生化机制知之甚少。我不想研究细胞环境中细胞内模式的形成和肌动蛋白的组装，而是想通过从纯化的成分自下而上的重组来建立极化细胞形态发生的最低要求。虽然这一过程在活细胞中是非常复杂和高度调控的，但我们已经达到了该领域的一个点，可以用这种方式解决一些精选的、相关的问题。具体地说，我想了解(I)膜相关的信号系统如何自组织成宏观的空间模式，以及(Ii)膜的极性如何被肌动蛋白细胞骨架利用来在细胞的相反端构建不同的结构。为此，我将把人工膜上的多蛋白质重组与先进的荧光成像技术相结合，并使用合成生物学方法。总体而言，这项工作有可能在系统生物化学水平上促进我们对细胞极性和形态发生的机制基础的理解。

Living cells organize their interior in a non-random, polarized manner to carry out specialized biological functions. Cell polarity arises from a complex interplay between the plasma membrane, associated proteins and cytoplasmic molecules. In eukaryotic cells, symmetry is in most cases initially broken at the level of membrane-bound molecules such as phosphatidylinositol lipids and Rho-type GTPases. These conserved signaling hubs synergistically control cell morphogenesis and movement through the actin cytoskeleton. While many of the components of these intimately linked systems have been defined, very little is known about the biochemical mechanisms underlying cell polarity and shape changes. Instead of studying intracellular pattern formation and actin assembly in the cellular environment, I want to establish the minimal requirements for polarized cell morphogenesis through bottom-up reconstitution from purified components. While this process is very complex and highly regulated in living cells, we have reached a point in the field where a number of select, pertinent questions can be addressed in such a manner. Specifically, I want to understand (i) how membrane-associated signaling systems self-organize into macroscopic spatial patterns and (ii) how membrane polarity can be harnessed by the actin cytoskeleton to construct distinct structures at opposing ends of the cell. To this aim, I will combine multiprotein reconstitution on artificial membranes with advanced fluorescence imaging techniques and employ synthetic biology methods. As a whole, this work has the potential to advance our understanding of the mechanistic foundations of cell polarity and morphogenesis at the systems biochemistry level.