Hosseini Kamran, Sbosny Leon, Poser Ina, Fischer-Friedrich Elisabeth
Cluster of Excellence Physics of Life, Technische Universität Dresden, Dresden, Germany; Biotechnology Center, Technische Universität Dresden, Dresden, Germany.
Biotechnology Center, Technische Universität Dresden, Dresden, Germany.
Biophys J. 2020 Sep 15;119(6):1091-1107. doi: 10.1016/j.bpj.2020.07.031. Epub 2020 Aug 7.
Mechanosensation of cells is an important prerequisite for cellular function, e.g., in the context of cell migration, tissue organization, and morphogenesis. An important mechanochemical transducer is the actin cytoskeleton. In fact, previous studies have shown that actin cross-linkers such as α-actinin-4 exhibit mechanosensitive properties in their binding dynamics to actin polymers. However, to date, a quantitative analysis of tension-dependent binding dynamics in live cells is lacking. Here, we present a, to our knowledge, new technique that allows us to quantitatively characterize the dependence of cross-linking lifetime of actin cross-linkers on mechanical tension in the actin cortex of live cells. We use an approach that combines parallel plate confinement of round cells, fluorescence recovery after photobleaching, and a mathematical mean-field model of cross-linker binding. We apply our approach to the actin cross-linker α-actinin-4 and show that the cross-linking time of α-actinin-4 homodimers increases approximately twofold within the cellular range of cortical mechanical tension, rendering α-actinin-4 a catch bond in physiological tension ranges.
细胞的机械感受是细胞功能的重要前提，例如在细胞迁移、组织构建和形态发生的背景下。一种重要的机械化学转导器是肌动蛋白细胞骨架。事实上，先前的研究表明，诸如α-辅肌动蛋白-4等肌动蛋白交联蛋白在其与肌动蛋白聚合物的结合动力学中表现出机械敏感特性。然而，迄今为止，尚缺乏对活细胞中张力依赖性结合动力学的定量分析。在此，据我们所知，我们提出了一种新技术，该技术使我们能够定量表征肌动蛋白交联蛋白的交联寿命对活细胞肌动蛋白皮层中机械张力的依赖性。我们采用了一种结合圆形细胞的平行板限制、光漂白后的荧光恢复以及交联蛋白结合的数学平均场模型的方法。我们将我们的方法应用于肌动蛋白交联蛋白α-辅肌动蛋白-4，并表明在皮层机械张力的细胞范围内，α-辅肌动蛋白-4同二聚体的交联时间增加了约两倍，使α-辅肌动蛋白-4在生理张力范围内成为一种捕捉键。
