Cells exist in different phenotypes and can transition between them. A phenotype may be characterized by many different aspects. Here, we focus on the example of whether the cell is adhered or suspended and choose particular parameters related to the structure and mechanics of the actin cortex. The cortex is essential to cell mechanics, morphology, and function, such as for adhesion, migration, and division of animal cells. To predict and control cellular functions and prevent malfunctioning, it is necessary to understand the actin cortex. The structure of the cortex governs cell mechanics; however, the relationship between the architecture and mechanics of the cortex is not yet well enough understood to be able to predict one from the other. Therefore, we quantitatively measured structural and mechanical cortex parameters, including cortical thickness, cortex mesh size, actin bundling, and cortex stiffness. These measurements required developing a combination of measurement techniques in scanning electron, expansion, confocal, and atomic force microscopy. We found that the structure and mechanics of the cortex of cells in interphase are different depending on whether the cell is suspended or adhered. We deduced general correlations between structural and mechanical properties and show how these findings can be explained within the framework of semiflexible polymer network theory. We tested the model predictions by perturbing the properties of the actin within the cortex using compounds. Our work provides an important step toward predictions of cell mechanics from cortical structures and suggests how cortex remodeling between different phenotypes impacts the mechanical properties of cells.

中文翻译：

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细胞皮层的结构和力学取决于位置和粘附状态


细胞以不同的表型存在并且可以在它们之间转换。表型可以通过许多不同的方面来表征。在这里，我们重点关注细胞是粘附还是悬浮的示例，并选择与肌动蛋白皮层的结构和力学相关的特定参数。皮质对于细胞力学、形态和功能至关重要，例如动物细胞的粘附、迁移和分裂。为了预测和控制细胞功能并防止发生故障，有必要了解肌动蛋白皮层。皮质的结构控制着细胞力学；然而，皮层的结构和力学之间的关系尚未得到充分理解，无法预测其中之一。因此，我们定量测量了皮层的结构和机械参数，包括皮层厚度、皮层网格大小、肌动蛋白成束和皮层刚度。这些测量需要开发扫描电子、膨胀、共焦和原子力显微镜测量技术的组合。我们发现，间期细胞皮层的结构和力学根据细胞是悬浮还是粘附而不同。我们推断了结构和机械性能之间的一般相关性，并展示了如何在半柔性聚合物网络理论的框架内解释这些发现。我们通过使用化合物扰乱皮层内肌动蛋白的特性来测试模型预测。我们的工作为从皮质结构预测细胞力学迈出了重要一步，并表明不同表型之间的皮质重塑如何影响细胞的力学特性。