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

上皮是覆盖哺乳动物体内和外表面的一层薄细胞层。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承受较大的变形和抵抗较大的力，以避免组织的机械故障。有人假设，在大变形中保持细胞结构完整性的核心角色是中间丝(IF)。IF是最丰富的细胞骨架成分之一，它们在大应变时具有独特的物理特性。然而，IF对细胞的物理性质以及细胞内和细胞间的产生的贡献仍然是难以捉摸的。这项建议的目的是最终检验IF作为“细胞安全带”的假说，并了解IF如何对上皮结构的机械阻力做出贡献。为此，我们将开发一个在三维上皮单分子层内拉伸细胞的模型系统。然后，我们将使用超分辨率技术在拉伸的细胞中成像IF以及它们与其他细胞骨架组件的相互作用。我们将测量基于IF的细胞-细胞接触上的局部力，并将直接利用光遗传学操纵IF。最后，我们将用先进的计算模型探索潜在的物理原理。该项目开发的技术将为研究IFS在发育和上皮性疾病中的作用提供新的强有力的工具。我们最终期望这个项目将有力地提高我们对IF对上皮结构的应力抵抗的机械贡献的理解。

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.