Cofilin produces newly polymerized actin filaments that are preferred for dendritic nucleation by the Arp2/3 complex
Cofilin produces newly polymerized actin filaments that are preferred for dendritic nucleation by the Arp2/3 complex
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DOI：
10.1016/s0960-9822(01)00629-7
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发表时间：
2002-01-08
期刊：
影响因子：
9.2
通讯作者：
Condeelis, J
中科院分区：
文献类型：
--
作者：
Ichetovkin, I;Grant, W;Condeelis, J
细胞运动过程中最早的事件之一是大量产生游离肌动蛋白倒刺末端，其伸长以在前缘尖端邻近质膜形成细丝。已提出cofilin和Arp 2/3复合物都有助于在细胞运动期间形成倒刺末端。对cofilin和Arp 2/3复合物在体内的功能进行评估的尝试表明，cofilin和Arp 2/3复合物都有助于肌动蛋白的聚合：cofilin通过切断而Arp 2/3通过成核和分支。为了确定cofilin和Arp 2/3复合物的活性是否相互作用，我们采用了基于光学显微镜的测定来直接观察两种蛋白质存在下的肌动蛋白聚合。结果表明，cofilin产生倒刺末端，以增加新鲜聚合的F-肌动蛋白的质量，但不直接影响Arp 2/3复合物的活性。然而，虽然ADP、ADP-Pi和新聚合的ATP-细丝都能够支持Arp 2/3介导的分支，但新聚合的F-肌动蛋白支持大多数Arp 2/3诱导的分支形成。结果表明，在体内，cofilln有助于倒刺末端的形成，通过诱导倒刺末端的数量的初始增加，导致增加的ATP-F-肌动蛋白，这反过来又支持活性Arp 2/3复合物的更高水平的树突成核。
One of the earliest events in the process of cell motility is the massive generation of free actin barbed ends which elongate to form filaments adjacent to the plasma membrane at the tip of the leading edge. Both cofilin and Arp2/3 complex have been proposed to contribute to barbed end formation during cell motility. Attempts to assess the functions of cofilin and Arp2/3 complex in vivo indicate that both cofilin and Arp2/3 complex contribute to actin polymerization: cofilin by severing and Arp2/3 by nucleating and branching. In order to determine if the activities of cofilin and Arp2/3 complex interact, we employed a light microscope-based assay to visualize actin polymerization directly in the presence of both proteins. The results indicate that cofilin generates barbed ends to increase the mass of freshly polymerized F-actin but does not directly affect the activity of Arp2/3 complex. However, while ADP, ADP-Pi, and newly polymerized ATP-filaments are all capable of supporting Arp2/3-mediated branching, newly polymerized F-actin supports most of the Arp2/3-induced branch formation. The results suggest that, in vivo, cofilln contributes to barbed end formation by inducing the initial increase in the number of barbed ends leading to increased ATP-F-actin, which in turn supports higher levels of dendritic nucleation by active Arp2/3 complex.