Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut, United States of America.
PLoS One. 2013 Sep 6;8(9):e73389. doi: 10.1371/journal.pone.0073389. eCollection 2013.
Adhesions are multi-molecular complexes that transmit forces generated by a cell's acto-myosin networks to external substrates. While the physical properties of some of the individual components of adhesions have been carefully characterized, the mechanics of the coupling between the cytoskeleton and the adhesion site as a whole are just beginning to be revealed. We characterized the mechanics of nascent adhesions mediated by the immunoglobulin-family cell adhesion molecule apCAM, which is known to interact with actin filaments. Using simultaneous visualization of actin flow and quantification of forces transmitted to apCAM-coated beads restrained with an optical trap, we found that adhesions are dynamic structures capable of transmitting a wide range of forces. For forces in the picoNewton scale, the nascent adhesions' mechanical properties are dominated by an elastic structure which can be reversibly deformed by up to 1 µm. Large reversible deformations rule out an interface between substrate and cytoskeleton that is dominated by a number of stiff molecular springs in parallel, and favor a compliant cross-linked network. Such a compliant structure may increase the lifetime of a nascent adhesion, facilitating signaling and reinforcement.
黏附物是多分子复合物，可将细胞的肌动球蛋白网络产生的力传递到外部基质。虽然黏附物的一些单个成分的物理特性已被仔细表征，但细胞骨架与黏附部位之间的整体耦联的力学特性才刚刚开始显现。我们描述了免疫球蛋白家族细胞黏附分子 apCAM 介导的初生黏附的力学特性，apCAM 已知与肌动蛋白丝相互作用。我们通过同时可视化肌动蛋白流并定量测量用光学阱约束的 apCAM 包被珠传递的力，发现黏附物是能够传递广泛范围力的动态结构。对于皮牛顿级别的力，初生黏附物的力学特性主要由弹性结构主导，该结构可被可逆地变形达 1 µm。大的可逆变形排除了由大量刚性分子弹簧并行主导的基质与细胞骨架之间的界面，并有利于顺应性交联网络。这种顺应性结构可能会增加初生黏附物的寿命，从而促进信号传递和强化。
