Maintenance of epithelial tissue integrity requires coordination between cell-cell adherens junctions, tight junctions (TJ), and the perijunctional actomyosin cytoskeleton. Here we addressed the hypothesis that alterations in TJ structure and remodeling of the actomyosin cytoskeleton modify epithelial mechanics. Current methods to measure supracellular mechanical properties disrupt intact monolayers, therefore, we developed a novel method using noncontact acoustic frequency-modulation atomic force microscopy (FM-AFM) and tested it on MDCK polarized monolayers. Our results show that double knockdown (dKD) of ZO-1/ZO-2 elevates the apical epithelial tension and effective viscosity. Interestingly, epithelial tension is more sensitive to inhibition of myosin II ATPase activity than to inhibition of ROCK activity, but viscosity is highly sensitive to both. Additionally, we showed epithelial intercellular pulling forces at tricellular junctions and adhesion forces in dKD cells are elevated with an increase in contractility. In conclusion, FM-AFM enables the physiological and quantitative investigation of mechanics in intact epithelium.

中文翻译：

---

使用无创声力光谱法分析极化上皮中的顶表面超细胞机械性能。

维持上皮组织的完整性需要细胞间粘附连接，紧密连接（TJ）和接合处周围的肌动球蛋白细胞骨架之间的协调。在这里，我们提出了假说，即TJ结构的改变和放线菌素细胞骨架的重塑会改变上皮力学。当前的测量细胞上机械性能的方法破坏了完整的单分子层，因此，我们开发了一种使用非接触声频调制原子力显微镜（FM-AFM）的新方法，并在MDCK极化单分子层上对其进行了测试。我们的结果表明，ZO-1 / ZO-2的双重敲低（dKD）会提高根尖上皮张力和有效粘度。有趣的是，上皮张力对肌球蛋白II ATPase活性的抑制比对ROCK活性的抑制更为敏感，但是粘度对两者都非常敏感。此外，我们显示在三细胞交界处的上皮细胞间拉力和dKD细胞的粘附力随着收缩力的增加而升高。总之，FM-AFM能够对完整上皮的力学进行生理和定量研究。