Regulation and Function of Intermediate Filaments in Cell Mechanics

在这个项目中，我们的主要假设是，细胞骨架IF，特别是由波形蛋白(VIF)组成的III型IF的组装状态和机械性能的变化，在调节细胞对机械和化学信号的微观机械性能方面发挥着重要作用。 这些研究至关重要，因为它们似乎是哺乳动物细胞骨架系统的主要元素，但它们在细胞运动中的具体功能仍不清楚。这6个项目的负责人，他们的研究目标如下：西北大学的R.Goldman将确定VIF系统如何响应机械和化学信号的变化，并将提纯和表征VIF组装和分解时形成的Vimentin前体。V.Gelfand，西北大学将 确定VIF与微管和肌动蛋白细丝的关系，确定负责VIF前体转运的分子马达，并研究VIF如何影响细胞骨架动力学和微管(MT)动力学。G.Danuser将检验以下假设，即VIF网络的形成涉及空间分布的装配线，这一过程涉及分子马达，以及VIF网络组装调制MT和微丝(MF)的组装。哈佛大学的D.Weitz博士将在体外确定从纯化的波形蛋白中制备的模拟VIF网络的微观机械特性，波形蛋白是从细胞和活细胞中分离出来的天然VIF网络。P.Janmey，宾夕法尼亚大学 将决定VIF网络如何有助于活细胞的微观机械特性，以及这种特性如何随着底物硬度和外力的变化而变化。康涅狄格大学的P·伯克哈德将利用生物物理技术和X射线结晶学来确定波形蛋白二聚体的结构和生物物理性质，并研究VIF组装中间体的形成。在所有这些研究中，将考察不同翻译后磷酸化事件的调节功能。

In this Program Project Grant our overarching hypothesis is that alterations in the assembly states and mechanical properties of cytoskeletal IF, specifically the type III IF composed of vimentin (VIF), play important roles in regulating the micromechanical properties of cells in response to mechano- and chemosignalling. These studies are critically important as IF are major elements of the cytoskeletal system of mammalian cells and yet their specific functions in cell motility remain unknown. The 6 Project Leaders, and their research aims are as follows: R. Goldman, Northwestern University, will determine how the vimentin IF (VIF) system changes in response to mechanical and chemical signals, and will purify and characterize the vimentin precursors that form as VIF assemble and disassemble. V. Gelfand, Northwestern University will determine the relationship between VIF with microtubules and actin filaments, identify the molecular motors responsible for translocating VIF precursors, and investigate how VIF affect cytoskeletal dynamics and microtubule (MT) dynamics. G. Danuser, Harvard University, will test the hypotheses that VIF network formation involves a spatially distributed assembly line, that this process involves molecular motors, and that VIF network assembly modulates assembly of MT and microfilaments (MF). D. Weitz, Harvard University, will determine the micromechanical properties of in vitro asembled VIF networks prepared from purified vimentin, native VIF networks isolated from cells and in living cells. P. Janmey, University of Pennsylvannia, will determine how the VIF network contributes to the micromechanical properties of living cells and how this changes in response to substrate stiffness and external forces. P. Burkhard, University of Connecticut, will use biophysical techniques and X-ray crystallography to determine the structure and biophysical properties of the vimentin dimer and study the formation of VIF assembly intermediates. In all of these studies, the regulatory function of different posttranslational phosphorylation events will be examined.