Institute for Integrative Biology of the Cell (I2BC), CNRS, Gif-sur-Yvette, Paris 91190, France.
Nat Rev Mol Cell Biol. 2017 Jun;18(6):389-401. doi: 10.1038/nrm.2016.172. Epub 2017 Mar 1.
Various cellular processes (including cell motility) are driven by the regulated, polarized assembly of actin filaments into distinct force-producing arrays of defined size and architecture. Branched, linear, contractile and cytosolic arrays coexist in vivo, and cells intricately control the number, length and assembly rate of filaments in these arrays. Recent in vitro and in vivo studies have revealed novel molecular mechanisms that regulate the number of filament barbed and pointed ends and their respective assembly and disassembly rates, thus defining classes of dynamically different filaments, which coexist in the same cell. We propose that a global treadmilling process, in which a steady-state amount of polymerizable actin monomers is established by the dynamics of each network, is responsible for defining the size and turnover of coexisting actin networks. Furthermore, signal-induced changes in the partitioning of actin to distinct arrays (mediated by RHO GTPases) result in the establishment of various steady-state concentrations of polymerizable monomers, thereby globally influencing the growth rate of actin filaments.
各种细胞过程（包括细胞运动）是由肌动蛋白丝的调节、极化组装驱动的，这些肌动蛋白丝组装成具有特定大小和结构的力产生阵列。分支的、线性的、收缩的和细胞质的阵列在体内共存，细胞精细地控制这些阵列中纤维的数量、长度和组装速率。最近的体外和体内研究揭示了新的分子机制，这些机制调节纤维的突刺和尖端的数量及其各自的组装和拆卸速率，从而定义了动态不同的纤维类别，这些纤维在同一细胞中共存。我们提出，一个全局的 treadmilling 过程，其中每个网络的动力学确定了聚合肌动蛋白单体的稳定数量，负责定义共存肌动蛋白网络的大小和周转率。此外，信号诱导的肌动蛋白向不同阵列的分配变化（由 RHO GTPases 介导）导致聚合单体的各种稳定浓度的建立，从而全局影响肌动蛋白纤维的生长速率。
