Kasas S, Wang X, Hirling H, Marsault R, Huni B, Yersin A, Regazzi R, Grenningloh G, Riederer B, Forrò L, Dietler G, Catsicas S
Institut des Neurosciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
Cell Motil Cytoskeleton. 2005 Oct;62(2):124-32. doi: 10.1002/cm.20086.
The cytoskeleton, composed of actin filaments, intermediate filaments, and microtubules, is a highly dynamic supramolecular network actively involved in many essential biological mechanisms such as cellular structure, transport, movements, differentiation, and signaling. As a first step to characterize the biophysical changes associated with cytoskeleton functions, we have developed finite elements models of the organization of the cell that has allowed us to interpret atomic force microscopy (AFM) data at a higher resolution than that in previous work. Thus, by assuming that living cells behave mechanically as multilayered structures, we have been able to identify superficial and deep effects that could be related to actin and microtubule disassembly, respectively. In Cos-7 cells, actin destabilization with Cytochalasin D induced a decrease of the visco-elasticity close to the membrane surface, while destabilizing microtubules with Nocodazole produced a stiffness decrease only in deeper parts of the cell. In both cases, these effects were reversible. Cell softening was measurable with AFM at concentrations of the destabilizing agents that did not induce detectable effects on the cytoskeleton network when viewing the cells with fluorescent confocal microscopy. All experimental results could be simulated by our models. This technology opens the door to the study of the biophysical properties of signaling domains extending from the cell surface to deeper parts of the cell.
细胞骨架由肌动蛋白丝、中间丝和微管组成，是一个高度动态的超分子网络，积极参与许多重要的生物学机制，如细胞结构、运输、运动、分化和信号传导。作为表征与细胞骨架功能相关的生物物理变化的第一步，我们开发了细胞组织的有限元模型，这使我们能够以比以往工作更高的分辨率解释原子力显微镜（AFM）数据。因此，通过假设活细胞在机械上表现为多层结构，我们能够分别识别可能与肌动蛋白和微管拆卸相关的表面和深层效应。在Cos-7细胞中，用细胞松弛素D破坏肌动蛋白的稳定性会导致靠近膜表面的粘弹性降低，而用诺考达唑破坏微管的稳定性只会使细胞较深部分的硬度降低。在这两种情况下，这些效应都是可逆的。当用荧光共聚焦显微镜观察细胞时，在破坏剂浓度下，AFM可以测量到细胞软化，而此时破坏剂对细胞骨架网络没有可检测到的影响。所有实验结果都可以由我们的模型模拟。这项技术为研究从细胞表面延伸到细胞较深部分的信号域的生物物理特性打开了大门。
