Membrane shape transition control in cellular membrane trafficking phenomena

 描述(由申请人提供)：膜的形状不仅作为细胞和细胞器的大小和结构的静态方面很重要，而且在许多过程中也是动态变化的，例如膜信号和运输。在质膜上，在内吞作用和丝状足细胞生成等过程中形成的内分泌和外分泌分别是膜曲率受到调节的一些最重要的现象。一类含有新月形支架的蛋白质被称为BAR(Bin/AmpliPhyin/RVS)结构域蛋白质，这类蛋白质的发现引起了人们对了解蛋白质如何与膜曲率耦合的兴趣日益增长。在许多与人类疾病有关的蛋白质中都发现了Bar结构域，其中许多包含疾病驱动突变和/或在病理条件下显示出变化的表达水平。与之相关的其他外周蛋白 膜曲率包括固有的无序蛋白质，如α-突触核蛋白，以及含有第10结构域的蛋白质，如Eepsin，这两种蛋白质都被认为参与了膜运输现象。 内吞作用是病原体进入细胞的主要机制。因此，提高对这一过程的机制和调节的理解是一个主要的生物医学相关问题。然而，尽管已经有90000多项研究成果仅研究了内吞作用，但这一过程的启动机制尚不清楚。这在一定程度上是由于这样一个事实，即在细胞中，许多内吞机制是并行运行的，而且对细胞中关键参数的实验控制程度有限。这个 这个项目的目标是了解膜形状转变是如何在内吞作用等过程中调节的。为了实现这一目标，我们开发了一种实验性的生物物理模型膜方法，它允许我们确定膜发生形状转变的条件。在这个工具的帮助下，我们将研究参与内吞作用的许多蛋白质的功能机制，并分离膜形状转换的关键调控因子。我们已经开发了一个理论框架，这将有助于对我们的发现进行机械化的解释。 虽然质膜在跨膜离子和脂质分布方面存在显著的不对称性，但模型膜的研究主要集中在对称膜上。我们将克服这一限制，并确定包括细胞骨架相互作用在内的膜不对称在多大程度上有助于外周蛋白质形成膜的功能。总体而言，该项目将对外周蛋白在健康和病理条件下变形膜的机制提供深远的见解。

 DESCRIPTION (provided by applicant): Membrane shape is important not only as a static aspect of size and structure of cells and organelles, but dynamically changes in numerous processes such as membrane signaling and trafficking. At the plasma membrane, the formation of in- and exvaginations, in processes such as endocytosis and the generation of filopodia, respectively, are some of the most important phenomena where membrane curvature is modulated. The discovery of a class of proteins which contain crescent shaped scaffolds called BAR (Bin/amphiphysin/Rvs) domain proteins, has prompted a growing interest in understanding how proteins couple with membrane curvature. BAR domains are found in numerous proteins implicated in human disease, and many contain disease driving mutations and/or show altered expression levels under pathological conditions. Additional peripheral proteins that are related to membrane curvature include intrinsically disordered proteins such as α-synuclein, as well as ENTH domain-containing proteins such as epsin, both of which are believed to be involved in membrane trafficking phenomena. Endocytosis is the primary mechanism by which pathogens enter cells. To improve the understanding of the mechanism and regulation of this process therefore is a matter of primary biomedical relevance. However, despite the fact that more than 90000 research contributions have investigated endocytosis alone, the mechanisms for initiation of this process are not understood. This is due in part to the fact that in cells numerous endocytic mechanisms operate in parallel and that the degree for experimental control of key parameters in cells is limited. The goal of this project is to understand how membrane shape transitions are regulated in processes such as endocytosis. In order to achieve this goal, we have developed an experimental biophysical model membrane approach that allows us to determine the conditions under which membranes undergo shape transitions. With the help of this tool, which consists of a combined micro- manipulation/fluorescence approach that is presently used exclusively in our laboratory, we will investigate mechanisms of the function of the many proteins involved in endocytosis, and isolate key modulators of membrane shape transitions. We already have developed a theoretical framework that will facilitate mechanistic interpretation of our findings. While plasma membranes experience significant asymmetry with respect to transmembrane ion and lipid distributions, model membrane research has largely focused on symmetric membranes. We will overcome this limitation and determine to what extent membrane asymmetry, which will include cytoskeletal interactions, contributes to the function of peripheral proteins in shaping membranes. Overall this project will provide far-reaching insight into the mechanisms by which peripheral proteins deform membranes under healthy and pathological conditions.