School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA.
Biophys J. 2012 Mar 7;102(5):1049-58. doi: 10.1016/j.bpj.2012.01.030. Epub 2012 Mar 6.
Many processes in eukaryotic cells, including the crawling motion of the whole cell, rely on the growth of branched actin networks from surfaces. In addition to their well-known role in generating propulsive forces, actin networks can also sustain substantial pulling loads thanks to their persistent attachment to the surface from which they grow. The simultaneous network elongation and surface attachment inevitably generate a force that opposes network growth. Here, we study the local dynamics of a growing actin network, accounting for simultaneous network elongation and surface attachment, and show that there exist several dynamical regimes that depend on both network elasticity and the kinetic parameters of actin polymerization. We characterize this in terms of a phase diagram and provide a connection between mesoscopic theories and the microscopic dynamics of an actin network at a surface. Our framework predicts the onset of instabilities that lead to the local detachment of the network and translate to oscillatory behavior and waves, as observed in many cellular phenomena and in vitro systems involving actin network growth, such as the saltatory dynamics of actin-propelled oil drops.
真核细胞中的许多过程，包括整个细胞的蠕动运动，都依赖于分支肌动蛋白网络从表面的生长。除了它们在产生推进力方面的众所周知的作用外，肌动蛋白网络还可以由于其与生长表面的持久附着而承受大量的拉力。网络的同时伸长和表面附着不可避免地产生一种与网络生长相反的力。在这里，我们研究了生长中的肌动蛋白网络的局部动力学，同时考虑了网络的伸长和表面的附着，并表明存在几种动力学状态，这取决于网络弹性和肌动蛋白聚合的动力学参数。我们用相图来描述这一点，并提供了介观理论和表面肌动蛋白网络微观动力学之间的联系。我们的框架预测了导致网络局部脱离的不稳定性的发生，这导致了观察到的许多细胞现象和涉及肌动蛋白网络生长的体外系统中的振荡行为和波，例如肌动蛋白驱动的油滴的跳跃动力学。
