A coat of filamentous actin prevents clustering of late-endosomal vacuoles in vivo
A coat of filamentous actin prevents clustering of late-endosomal vacuoles in vivo
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DOI：
10.1016/j.cub.2003.09.037
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发表时间：
2003-10-14
期刊：
影响因子：
9.2
通讯作者：
Maniak, M
中科院分区：
文献类型：
--
作者：
Drengk, A;Fritsch, J;Maniak, M
内吞途径依赖于肌动蛋白细胞骨架。肌动蛋白有助于质膜的内化[1，2]和随后的运输步骤，如通过细胞质的推进[3，4]，吞噬体与早期内体的融合[5]，以及从早期内体到晚期内体的运输[6，7]。哺乳动物内体和酵母液泡的体外研究表明肌动蛋白参与膜融合[8，9]。在这里，我们研究了在网骨藻中围绕晚期内体的肌动蛋白外壳的功能[10]。Latrunculin处理导致这些内体聚集成葡萄样簇，并完全阻断内吞标志物的进展。此外，细胞聚集并停止移动。由于这种药物治疗同时干扰细胞中的所有肌动蛋白组装，我们使用了一种新的靶向方法来专门研究细胞骨架在一个亚细胞位置的功能。为此，我们构建了一个杂交蛋白靶向cofilin，肌动蛋白解聚蛋白，晚期内体。因此，内体区室失去了它们的肌动蛋白外套和聚集，但这些细胞保持形态正常，内吞标记物运输的动力学没有改变。因此，肌动蛋白外壳阻止了内体的聚集，这可能是阻止它们对接和融合的一种保护机制。
The endocytic pathway depends on the actin cytoskeleton. Actin contributes to internalization at the plasma membrane [1, 2] and to subsequent trafficking steps like propulsion through the cytoplasm [3, 4], fusion of phagosomes with early endosomes [5], and transport from early to late endosomes [6,7]. In vitro studies with mammalian endosomes and yeast vacuoles implicate actin in membrane fusion [8, 9]. Here, we investigate the function of the actin coat that surrounds late endosomes in Dictyostelium [10]. Latrunculin treatment leads to aggregation of these endosomes into grapelike clusters and completely blocks progression of endocytic marker. In addition, the cells round up and stop moving. Because this drug treatment perturbs all actin assemblies in the cell simultaneously, we used a novel targeting approach to specifically study the function of the cytoskeleton in one subcellular location. To this end, we constructed a hybrid protein targeting cofilin, an actin depolymerizing protein, to late endosomes. As a consequence, the endosomal compartments lost their actin coats and aggregated, but these cells remained morphologically normal, and the kinetics of endocytic marker trafficking were unaltered. Therefore, the actin coat prevents the clustering of endosomes, which could be one safeguard mechanism precluding their docking and fusion.