Direct observation of dendritic actin filament networks nucleated by Arp2/3 complex and WASP/Scar proteins
Direct observation of dendritic actin filament networks nucleated by Arp2/3 complex and WASP/Scar proteins
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DOI：
10.1038/35010008
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发表时间：
2000-04-27
期刊：
影响因子：
64.8
通讯作者：
Pollard, TD
中科院分区：
文献类型：
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作者：
Blanchoin, L;Amann, KJ;Pollard, TD
大多数有核细胞通过伸展伪足来爬行，伪足由质膜前缘后面细胞质中肌动蛋白细丝的聚合驱动(1，2)。这些肌动蛋白细丝通过Y形分支连接成网络，每个细丝的尖端连接到另一根细丝的一侧，快速生长的带刺的一端朝向前方(3)。由于Arp2/3复合体在体外使肌动蛋白聚合成核，并将尖端连接到另一根细丝的侧面，因此提出了一种树枝形成核模型4，其中Arp2/3复合体从较老的细丝侧面引发微丝。在这里，我们报告，通过使用光学显微镜分析，许多新的机制特征。分支发生在Wiskott-Aldrich综合征蛋白(WASP)或SCAR蛋白激活的Arp2/3复合体的成核过程中，而不是之后；帽蛋白和Profilin与Arp2/3复合体协同作用有利于分支成核；老化的肌动蛋白细丝释放磷酸盐有利于Arp2/3复合体从细丝的尖端解离；Arp2/3复合体创建的分支相对刚性。这些特性导致分支肌动蛋白网络在被WASP/SCAR家族的蛋白质激活后自动组装，并有利于网络近端区域的选择性拆解。
Most nucleated cells crawl about by extending a pseudopod that is driven by the polymerization of actin filaments in the cytoplasm behind the leading edge of the plasma membrane(1,2). These actin filaments are linked into a network by Y-branches, with the pointed end of each filament attached to the side of another filament and the rapidly growing barbed end facing forward(3). Because Arp2/3 complex nucleates actin polymerization and links the pointed end to the side of another filament in vitro, a dendritic nucleation model has been proposed 4 in which Arp2/3 complex initiates filaments from the sides of older filaments. Here we report, by using a light microscopy assay, many new features of the mechanism. Branching occurs during, rather than after, nucleation by Arp2/3 complex activated by the Wiskott-Aldrich syndrome protein (WASP) or Scar protein; capping protein and profilin act synergistically with Arp2/3 complex to favour branched nucleation; phosphate release from aged actin filaments favours dissociation of Arp2/3 complex from the pointed ends of filaments; and branches created by Arp2/3 complex are relatively rigid. These properties result in the automatic assembly of the branched actin network after activation by proteins of the WASP/ Scar family and favour the selective disassembly of proximal regions of the network.