Department of Physics, MacDonald Hall, 150 Louis Pasteur, University of Ottawa, Ottawa, ON, Canada K1N 6N5.
Department of Physics, MacDonald Hall, 150 Louis Pasteur, University of Ottawa, Ottawa, ON, Canada K1N 6N5; Department of Biology, Gendron Hall, 30 Marie Curie, University of Ottawa, Ottawa, ON, Canada K1N 6N5; Institute for Science, Society and Policy, Desmarais Building, 55 Laurier Avenue East, University of Ottawa, Ottawa, ON, Canada K1N 6N5.
Exp Cell Res. 2014 Mar 10;322(1):21-9. doi: 10.1016/j.yexcr.2013.12.027. Epub 2014 Jan 8.
The mechanical properties of living cells are highly regulated by remodeling dynamics of the cytoarchitecture, and are linked to a wide variety of physiological and pathological processes. Microtubules (MT) and actomyosin contractility are both involved in regulating focal adhesion (FA) size and cortical elasticity in living cells. Although several studies have examined the effects of MT depolymerization or actomyosin activation on biological processes, very few have investigated the influence of both on the mechanical properties, FA assembly, and spreading of fibroblast cells. Here, we examine how activation of both processes modulates cortical elasticity as a function of time. Enhancement of contractility (calyculin A treatment) or the depolymerization of MTs (nocodazole treatment) individually caused a time-dependent increase in FA size, decrease in cell height and an increase in cortical elasticity. Surprisingly, sequentially stimulating both processes led to a decrease in cortical elasticity, loss of intact FAs and a concomitant increase in cell height. Our results demonstrate that loss of MTs disables the ability of fibroblast cells to maintain increased contractility and cortical elasticity upon activation of myosin-II. We speculate that in the absence of an intact MT network, a large amount of contractile tension is transmitted directly to FA sites resulting in their disassembly. This implies that tension-mediated FA growth may have an upper bound, beyond which disassembly takes place. The interplay between cytoskeletal remodeling and actomyosin contractility modulates FA size and cell height, leading to dynamic time-dependent changes in the cortical elasticity of fibroblast cells.
细胞的机械特性受到细胞结构重构动力学的高度调节，并与各种生理和病理过程相关。微管（MT）和肌动球蛋白收缩力都参与调节活细胞中的粘着斑（FA）大小和皮质弹性。尽管有几项研究检查了 MT 解聚或肌球蛋白激活对生物过程的影响，但很少有研究调查这两种过程对成纤维细胞的机械特性、FA 组装和扩散的影响。在这里，我们研究了这两种过程的激活如何随时间调节皮质弹性。收缩力的增强（calyculin A 处理）或 MT 的解聚（nocodazole 处理）单独导致 FA 大小随时间增加、细胞高度降低和皮质弹性增加。令人惊讶的是，顺序刺激这两种过程会导致皮质弹性降低、完整 FA 的丧失以及细胞高度的相应增加。我们的结果表明，失去 MT 会使成纤维细胞在肌球蛋白-II 激活时丧失维持增加的收缩力和皮质弹性的能力。我们推测，在没有完整的 MT 网络的情况下，大量的收缩张力直接传递到 FA 位点，导致其解体。这意味着张力介导的 FA 生长可能有一个上限，超过这个上限就会发生解体。细胞骨架重构和肌球蛋白收缩力之间的相互作用调节 FA 大小和细胞高度，导致成纤维细胞皮质弹性的动态时变。
