Étienne Jocelyn, Fouchard Jonathan, Mitrossilis Démosthène, Bufi Nathalie, Durand-Smet Pauline, Asnacios Atef
Université Grenoble Alpes and CNRS, Laboratoire Interdisciplinaire de Physique, F-38000 Grenoble, France; and
Université Paris-Diderot and CNRS, Sorbonne Paris Cité, Laboratoire Matière et Systèmes Complexes, UMR 7057, Paris, France.
Proc Natl Acad Sci U S A. 2015 Mar 3;112(9):2740-5. doi: 10.1073/pnas.1417113112. Epub 2015 Feb 17.
Living cells adapt and respond actively to the mechanical properties of their environment. In addition to biochemical mechanotransduction, evidence exists for a myosin-dependent purely mechanical sensitivity to the stiffness of the surroundings at the scale of the whole cell. Using a minimal model of the dynamics of actomyosin cortex, we show that the interplay of myosin power strokes with the rapidly remodeling actin network results in a regulation of force and cell shape that adapts to the stiffness of the environment. Instantaneous changes of the environment stiffness are found to trigger an intrinsic mechanical response of the actomyosin cortex. Cortical retrograde flow resulting from actin polymerization at the edges is shown to be modulated by the stress resulting from myosin contractility, which in turn, regulates the cell length in a force-dependent manner. The model describes the maximum force that cells can exert and the maximum speed at which they can contract, which are measured experimentally. These limiting cases are found to be associated with energy dissipation phenomena, which are of the same nature as those taking place during the contraction of a whole muscle. This similarity explains the fact that single nonmuscle cell and whole-muscle contraction both follow a Hill-like force-velocity relationship.
活细胞会主动适应并对其周围环境的力学特性做出反应。除了生化机械转导外，有证据表明在整个细胞尺度上存在一种依赖肌球蛋白的对周围环境硬度的纯机械敏感性。通过使用肌动球蛋白皮层动力学的最小模型，我们表明肌球蛋白动力冲程与快速重塑的肌动蛋白网络之间的相互作用导致了力和细胞形状的调节，使其适应环境的硬度。研究发现，环境硬度的瞬时变化会触发肌动球蛋白皮层的内在机械反应。边缘处肌动蛋白聚合导致的皮层逆行流被证明受到肌球蛋白收缩性产生的应力调节，而这又以力依赖的方式调节细胞长度。该模型描述了细胞能够施加的最大力以及它们能够收缩的最大速度，这些都是通过实验测量得到的。发现这些极限情况与能量耗散现象相关，这些现象与整个肌肉收缩过程中发生的现象具有相同的性质。这种相似性解释了单个非肌肉细胞和整个肌肉收缩都遵循类似希尔力 - 速度关系这一事实。
