Actin-depolymerizing factor and cofilin-1 play overlapping roles in promoting rapid F-actin depolymerization in mammalian nonmuscle cells
Actin-depolymerizing factor and cofilin-1 play overlapping roles in promoting rapid F-actin depolymerization in mammalian nonmuscle cells
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DOI：
10.1091/mbc.e04-07-0555
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发表时间：
2005-02-01
影响因子：
3.3
通讯作者：
Lappalainen, P
中科院分区：
文献类型：
--
作者：
Hotulainen, P;Paunola, E;Lappalainen, P
肌动蛋白解聚因子(ADF)/纤丝蛋白是存在于所有真核生物中的一种小的肌动蛋白结合蛋白。在体外，ADF/cofilins通过解聚和切断肌动蛋白细丝来促进肌动蛋白的动力学。然而，ADF/cofilins是否通过分解“旧的”肌动蛋白细丝或通过它们的切断活性促进肌动蛋白细丝的组装来促进细胞内肌动蛋白的动力学是有争议的问题。哺乳动物ADF/cofilin的分析因多种异构体的存在而变得更加复杂，这可能通过不同的机制影响肌动蛋白的动力学。我们发现ADF和cofilin-1两种异构体在小鼠NIH 3T3、B16F1和Neuro 2A细胞中都有表达。SiRNA耗尽cofilin-1和/或ADF会导致F-肌动蛋白的积聚，并导致细胞尺寸的增加。Cofilin-1和ADF似乎在细胞中扮演着重叠的角色，因为其中一种蛋白质的击倒表型可以通过另一种蛋白质的过度表达来挽救。Cofilin-1和ADF敲除细胞在细胞运动和胞质分裂方面也存在缺陷，当ADF和Cofilin-1都被耗尽时，这些缺陷最为明显。光漂白后的荧光恢复分析和肌动蛋白单体隔离药物Latrunculin-A的研究表明，这些表型是由于肌动蛋白细丝解聚速率降低引起的。这些数据表明，哺乳动物的ADF和cofilin-1通过解聚肌动蛋白细丝来促进细胞骨架的动力学，这种活性对细胞质分裂和细胞运动等几个过程是至关重要的。
Actin-depolymerizing factor (ADF)/cofilins are small actin-binding proteins found in all eukaryotes. In vitro, ADF/cofilins promote actin dynamics by depolymerizing and severing actin filaments. However, whether ADF/cofilins contribute to actin dynamics in cells by disassembling "old" actin filaments or by promoting actin filament assembly through their severing activity is a matter of controversy. Analysis of mammalian ADF/cofilins is further complicated by the presence of multiple isoforms, which may contribute to actin dynamics by different mechanisms. We show that two isoforms, ADF and cofilin-1, are expressed in mouse NIH 3T3, B16F1, and Neuro 2A cells. Depleting cofilin-1 and/or ADF by siRNA leads to an accumulation of F-actin and to an increase in cell size. Cofilin-1 and ADF seem to play overlapping roles in cells, because the knockdown phenotype of either protein could be rescued by overexpression of the other one. Cofilin-1 and ADF knockdown cells also had defects in cell motility and cytokinesis, and these defects were most pronounced when both ADF and cofilin-1 were depleted. Fluorescence recovery after photobleaching analysis and studies with an actin monomer-sequestering drug, latrunculin-A, demonstrated that these phenotypes arose from diminished actin filament depolymerization rates. These data suggest that mammalian ADF and cofilin-1 promote cytoskeletal dynamics by depolymerizing actin filaments and that this activity is critical for several processes such as cytokinesis and cell motility.