Actin Polymerization Controls the Organization of WASH Domains at the Surface of Endosomes
Actin Polymerization Controls the Organization of WASH Domains at the Surface of Endosomes
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DOI：
10.1371/journal.pone.0039774
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发表时间：
2012-06-21
期刊：
影响因子：
3.7
通讯作者：
Gautreau, Alexis
中科院分区：
文献类型：
--
作者：
Derivery, Emmanuel;Helfer, Emmanuele;Gautreau, Alexis
内体中货物的分选通过其选择性富集到分选平台中而发生，在分选平台中产生运输中间体。直接结合脂质的WASH复合物激活Arp 2/3复合物，从而激活肌动蛋白聚合到这种分选平台上。在这里，我们分析了肌动蛋白聚合的作用，在生理学的内涵体域含有WASH使用定量图像分析。已知肌动蛋白解聚可扩大内体。使用一种新的共定位方法，是不敏感的异质性的大小和形状的内体，我们进一步表明，防止产生分支肌动蛋白网络诱导内体积累的WASH复合物。此外，我们发现，肌动蛋白解聚诱导内体WASH光漂白后的恢复显着减少。这一结果表明了一种内在的周转，其中肌动蛋白网络，即WASH复合物的产物，通过促进WASH复合物从内体脱离而有助于WASH复合物的动态交换。我们的实验还提供了证据，肌动蛋白聚合的作用，在横向区室化的内体：几个WASH域存在于扩大的内体的表面，然而，WASH域合并后，肌动蛋白解聚或Arp 2/3耗尽。因此，分支肌动蛋白网络参与WASH结构域大小的调节。这种调节在膜断裂的潜在作用进行了讨论。
Sorting of cargoes in endosomes occurs through their selective enrichment into sorting platforms, where transport intermediates are generated. The WASH complex, which directly binds to lipids, activates the Arp2/3 complex and hence actin polymerization onto such sorting platforms. Here, we analyzed the role of actin polymerization in the physiology of endosomal domains containing WASH using quantitative image analysis. Actin depolymerization is known to enlarge endosomes. Using a novel colocalization method that is insensitive to the heterogeneity of size and shape of endosomes, we further show that preventing the generation of branched actin networks induces endosomal accumulation of the WASH complex. Moreover, we found that actin depolymerization induces a dramatic decrease in the recovery of endosomal WASH after photobleaching. This result suggests a built-in turnover, where the actin network, i.e. the product of the WASH complex, contributes to the dynamic exchange of the WASH complex by promoting its detachment from endosomes. Our experiments also provide evidence for a role of actin polymerization in the lateral compartmentalization of endosomes: several WASH domains exist at the surface of enlarged endosomes, however, the WASH domains coalesce upon actin depolymerization or Arp2/3 depletion. Branched actin networks are thus involved in the regulation of the size of WASH domains. The potential role of this regulation in membrane scission are discussed.