The functional role of the endocytic protein syndapin in controlling actin cytoskeletal organization and dynamics

肌动蛋白细胞骨架是一个复杂而高度组织化的结构，但它是动态的，并对各种内部和外部线索作出反应。由于肌动蛋白和Arp2/3复合物（肌动蛋白成核机制）是基本的、通用的组成部分，因此肌动蛋白参与的细胞骨架功能与各种细胞过程的特定联系将需要不同的分子控制Arp2/3复合物。其中一些特异性可能是由不同的Arp2/3复合物激活因子提供的，其中大多数属于Scar/WASP蛋白家族，但大多数特异性可能涉及不同的蛋白质组与这些分子相互作用并控制它们。对于syndapins，我们已经确定了一些蛋白质，它们是膜运输过程的一部分，但也与Arp2/3复合物激活剂N-WASP相互作用。在这项研究中，我们想要解决与Scar/WASP超家族蛋白的相互作用是否是syndapin功能的一般特征，研究syndapin/N-WASP相互作用触发肌动蛋白聚合以及肌动蛋白驱动运动的分子机制，并对所涉及的蛋白质、蛋白质结构域及其相互作用进行详细的机械分析。为此，我们将使用纯化蛋白进行体外重构分析。我们还将研究突触蛋白和肌动蛋白依赖的体内形态变化，并试图深入了解肌动蛋白成核机制的调节以及肌动蛋白细胞骨架与细胞膜的功能界面的组织。

The actin cytoskeleton is a complex and highly organized structure, yet it is dynamic and responds to a variety of inner and outer clues. Since actin and the Arp2/3 complex - the actin nucleation machinery - are basic, general components, a specific linkage of cytoskeletal functions to the huge variety of cellular processes actin is involved in will require distinct molecules controlling the Arp2/3 complex. Some of this specificity may be provided by the different Arp2/3 complex activators, the majority of which belong to the Scar/WASP protein family, but most of this specificity may involve a diverse group of proteins interacting with these molecules and controlling them. With syndapins, we have identified proteins that are part of membrane trafficking processes but also interact with the Arp2/3 complex activator N-WASP. In this study, we want to address whether interaction with Scar/WASP superfamily proteins is a general feature of syndapin function, examine the molecular mechanisms by which the syndapin/N-WASP interaction we have previously identified triggers actin polymerization as well as actin-driven motility and conduct a detailed mechanistical analysis of the involved proteins, protein domains and their interactions. For this purpose, we will employ in vitro reconstitution assays using purified proteins. We will also study syndapin- and actin-dependent morphology changes in vivo and try to gain insights into the regulation of the actin nucleation machinery and into the organization of the functional interface of the actin cytoskeleton with cellular membranes.