Gov Nir S, Bernheim-Groswasser Anne
Bioarchitecture. 2012 Jan 1;2(1):11-14. doi: 10.4161/bioa.19739.
Actin polymerization plays a major role in many cellular processes, including cell motility, vesicle trafficking, and pathogen propulsion. The transformation of the (protrusive) polymerization forces into directed motion requires that the growing filaments are positioned next to the surface. This is achieved by localization of surface actin nucleators (WASP), which then activate Arp2/3 complex to form new actin branches. Yet, the same surface-bound WASP molecule which initiates the nucleation of new actin branches, also inherently prevents the translation of the polymerization forces into motion, essentially because the WASP molecule has to be in contact with the network during the formation of the new branch. In our recent paper we show that cortactin relaxes this internal inhibition by enhancing the release of WASP-VCA molecule from the new branching site after nucleation is initiated. We show that this enhanced release has two major effects; it increases the turnover rate of branching per WASP molecule, and it decreases the friction-like force caused by the binding of the moving surface with respect to the growing actin network.
肌动蛋白聚合在许多细胞过程中发挥着重要作用，包括细胞运动、囊泡运输和病原体推进。将（突出的）聚合力转化为定向运动需要生长的细丝位于表面附近。这是通过表面肌动蛋白成核剂（WASP）的定位来实现的，然后WASP激活Arp2/3复合物以形成新的肌动蛋白分支。然而，启动新肌动蛋白分支成核的同一个表面结合的WASP分子，本质上也会阻止聚合力转化为运动，这主要是因为在新分支形成过程中，WASP分子必须与网络接触。在我们最近的论文中，我们表明皮层肌动蛋白通过在成核启动后增强WASP-VCA分子从新分支位点的释放来缓解这种内部抑制。我们表明这种增强的释放有两个主要作用；它增加了每个WASP分子的分支周转率，并且它降低了移动表面与生长的肌动蛋白网络结合所产生的类似摩擦力。
