Lorenz Charlotta, Forsting Johanna, Style Robert W, Klumpp Stefan, Köster Sarah
Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland.
Matter. 2023 Jun 7;6(6):2019-2033. doi: 10.1016/j.matt.2023.04.014.
Cell mechanics are determined by an intracellular biopolymer network, including intermediate filaments that are expressed in a cell-type-specific manner. A prominent pair of intermediate filaments are keratin and vimentin, as they are expressed by non-motile and motile cells, respectively. Therefore, the differential expression of these proteins coincides with a change in cellular mechanics and dynamic properties of the cells. This observation raises the question of how the mechanical properties already differ on the single filament level. Here, we use optical tweezers and a computational model to compare the stretching and dissipation behavior of the two filament types. We find that keratin and vimentin filaments behave in opposite ways: keratin filaments elongate but retain their stiffness, whereas vimentin filaments soften but retain their length. This finding is explained by fundamentally different ways to dissipate energy: viscous sliding of subunits within keratin filaments and non-equilibrium α helix unfolding in vimentin filaments.
细胞力学由细胞内生物聚合物网络决定，该网络包括以细胞类型特异性方式表达的中间丝。一对突出的中间丝是角蛋白和波形蛋白，因为它们分别由非运动细胞和运动细胞表达。因此，这些蛋白质的差异表达与细胞力学和细胞动态特性的变化相一致。这一观察结果提出了一个问题，即单丝水平上的力学性能是如何已经存在差异的。在这里，我们使用光镊和计算模型来比较这两种丝的拉伸和耗散行为。我们发现角蛋白丝和波形蛋白丝的行为相反：角蛋白丝伸长但保持其刚度，而波形蛋白丝变软但保持其长度。这一发现可以通过根本不同的能量耗散方式来解释：角蛋白丝内亚基的粘性滑动和波形蛋白丝中非平衡α螺旋的展开。
