The role of intermediate filaments in stress resistance in 3D epithelial structures

上皮细胞是覆盖哺乳动物体内内外表面的薄细胞层。因此，它必须不断地承受和施加机械应力。上皮内的细胞必须能够经受大的变形并抵抗大的力以避免组织的机械失效。它已被假设为保持暴露于大变形的细胞的结构完整性的核心作用是由中间丝（IF）。IFs是最丰富的细胞骨架成分之一，它们在大菌株中具有独特的物理性质。然而，IF对细胞的物理性质以及细胞间和细胞内的产生的贡献仍然难以捉摸。该提案的目标是最终测试IFs作为“细胞安全带”的假设，并了解IFs如何有助于上皮结构的机械阻力。为此，我们将开发一个模型系统，用于拉伸细胞内的三维上皮单层。然后，我们将图像的IF和他们的相互作用与其他细胞骨架组件在拉伸细胞与超分辨率技术。我们将测量基于IF的细胞-细胞接触的局部力，我们将用光遗传学直接操纵IF。最后，我们将探索先进的计算模型的基本物理原理。该项目开发的技术将为研究IFs在发育和上皮疾病中的作用提供新的强大工具。我们最终期望，这个项目将大大提高我们的理解的机械贡献的IF的抗应激上皮结构。

The epithelium is a thin cellular layer that covers inner and outer surfaces in mammalian bodies. Thereby, it constantly has to withstand and exert mechanical stresses. The cells within the epithelium must be able to both undergo large deformations and resist large forces to avoid mechanical failure of the tissue. It has been hypothesised that a central role for retaining the structural integrity of cells exposed to large deformations is played by intermediate filaments (IFs). IFs are one of the most abundant cytoskeletal components and they feature unique physical properties at large strains. However, the contribution of IFs to the physical properties of cells and the generation of inter- and intracellular remains elusive. The goal of this proposal is to conclusively test the hypothesis of IFs acting as a “cellular safety belt” and to understand how IFs can contribute to the mechanical resistance of epithelial structures. For this purpose, we will develop a model system for stretching cells within a three-dimensional epithelial monolayer. We will then image IFs and their interaction with other cytoskeletal components in stretched cells with super resolution techniques. We will measure the local forces on IF-based cell-cell contacts and we will directly manipulate IFs with optogenetics. Finally, we will explore the underlying physical principles with advanced computational models. The techniques developed in this project will provide new powerful tools to study the role of IFs in development and epithelial diseases. We ultimately expect that this project will strongly improve our understanding of the mechanical contribution of IFs to the stress resistance of epithelial structures.