Distinct roles for Arp2/3 regulators in actin assembly and endocytosis.
Distinct roles for Arp2/3 regulators in actin assembly and endocytosis.
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ARP2/3调节剂在肌动蛋白组装和内吞作用中的不同作用。
DOI：
10.1371/journal.pbio.0060001
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发表时间：
2008-01
期刊：
影响因子：
9.8
通讯作者：
Cooper JA
中科院分区：
文献类型：
--
作者：
Galletta BJ;Chuang DY;Cooper JA
Arp2/3复合体在许多细胞过程中对肌动蛋白的组装和运动是必不可少的，在体外发现了大量的蛋白质结合和调节它。一个关键的挑战是了解这些蛋白质在细胞中的作用，特别是在存在多个调节器的情况下。在一项对酵母中伴随内吞作用的顺序多组分肌动蛋白组装过程的系统研究中，我们检查并比较了黄蜂、两个I型肌球蛋白和另外两个Arp2/3激活剂的作用，以及Arp2/3的抑制物--柯拉宁的作用。高速荧光成像的定量分析揭示了这些调节因子的个别功能，部分表现在新的表型上。我们得出结论，Arp2/3调节器在驱动酵母内吞作用的肌动蛋白组装过程中具有不同和重叠的作用。内吞肌动蛋白斑块的形成、胞内小泡的产生以及小泡进入细胞质的运动对不同的Arp2/3调节剂表现出不同的依赖性。对这些角色的了解有助于深入了解肌动蛋白组装的树突成核模型在体内的相关性。一个由不断生长的肌动蛋白细丝组成的分支网络推动着细胞膜，为某些细胞的运动提供力量。Arp2/3复合体通过产生新的细丝和分支点在这一过程中发挥核心作用。许多蛋白质与Arp2/3结合，并在某些情况下调节Arp2/3。在细胞中，重要的是确定在复杂的、多步骤的细胞运动中，许多Arp2/3调节因子中的每一个在产生肌动蛋白网络中的确切作用。在酵母中，内吞作用发生在质膜上，与皮质肌动蛋白斑块的组装和移动有关，皮质肌动蛋白斑块包含六个Arp2/3调节因子。我们使用肌动蛋白斑块作为模型系统来确定这些调控因子在斑块组装和移动过程中的具体作用。我们使用高速视频显微镜，结合计算机辅助颗粒跟踪，监测带有一个或多个Arp2/3调节器突变的细胞中荧光标记的肌动蛋白斑块的移动。这项技术的敏感性使我们能够识别以前未被认识的Arp2/3调节器的功能，并在肌动蛋白斑块组装和移动过程中为每个调节器分配一个特定的角色。我们的结果表明，Arp2/3调节蛋白在肌动蛋白斑块运动的某些阶段扮演着重叠的角色，但在其他阶段扮演着不同的角色。此外，我们的结果为肌动蛋白细丝网络的组装如何推动内吞泡离膜的运动提供了新的见解。由Arp2/3复合体成核的肌动蛋白细丝分支网络为许多细胞运动提供动力。对发芽酵母中肌动蛋白斑块运动的定量分析表明，Arp2/3调节因子在内吞作用中的作用是不同的和重叠的。
The Arp2/3 complex is essential for actin assembly and motility in many cell processes, and a large number of proteins have been found to bind and regulate it in vitro. A critical challenge is to understand the actions of these proteins in cells, especially in settings where multiple regulators are present. In a systematic study of the sequential multicomponent actin assembly processes that accompany endocytosis in yeast, we examined and compared the roles of WASp, two type-I myosins, and two other Arp2/3 activators, along with that of coronin, which is a proposed inhibitor of Arp2/3. Quantitative analysis of high-speed fluorescence imaging revealed individual functions for the regulators, manifested in part by novel phenotypes. We conclude that Arp2/3 regulators have distinct and overlapping roles in the processes of actin assembly that drive endocytosis in yeast. The formation of the endocytic actin patch, the creation of the endocytic vesicle, and the movement of the vesicle into the cytoplasm display distinct dependencies on different Arp2/3 regulators. Knowledge of these roles provides insight into the in vivo relevance of the dendritic nucleation model for actin assembly. A branched network of growing actin filaments, pushing against a membrane, provides the force for certain cellular movements. The Arp2/3 complex plays a central role in this process by generating new filaments and branch points. A number of proteins bind to and, in some cases, regulate Arp2/3. It is important to determine, in the cell, the precise roles of each of the many Arp2/3 regulators in generating actin networks during a complex, multistep, cellular movement. In yeast, endocytosis occurs at the plasma membrane in association with the assembly and movement of cortical actin patches, which contain six Arp2/3 regulators. We have used the actin patch as a model system to determine the specific roles of these regulators during patch assembly and movement. We used high-speed video microscopy, coupled with computer-aided particle tracking, to monitor the movement of fluorescently labeled actin patches in cells with one or more mutations of the Arp2/3 regulators. The sensitivity of this technique allowed us to identify previously unappreciated functions for Arp2/3 regulators and to assign each of the regulators a specific role during actin patch assembly and movement. Our results demonstrate that Arp2/3 regulatory proteins play overlapping roles at certain stages of actin patch movement, but distinct roles at other stages. In addition, our results provide new insight into how the assembly of an actin filament networks powers the movement of endocytic vesicles away from the membrane. Branched networks of actin filaments, nucleated by the Arp2/3 complex, power many cellular movements. Quantitative analysis of actin patch motility in budding yeast reveals distinct and overlapping roles for Arp2/3 regulators in endocytosis.
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影响因子：
7.8
作者：
Huckaba, TM;Gay, AC;Pantalena, LF;Yang, HC;Pon, LA
通讯作者：
Pon, LA
影响因子：
56.9
作者：
Geli, MI;Riezman, H
通讯作者：
Riezman, H
影响因子：
64.5
作者：
Kaksonen, M;Toret, CP;Drubin, DG
通讯作者：
Drubin, DG
影响因子：
16
作者：
Goley, ED;Rodenbusch, SE;Welch, MD
通讯作者：
Welch, MD
DOI：
10.1083/jcb.200105061
发表时间：
2001-08-20
期刊：
The Journal of cell biology
影响因子：
--
作者：
Olazabal IM;Machesky LM
通讯作者：
Machesky LM