Evidence for two endocytic transport pathways in plant cells
Evidence for two endocytic transport pathways in plant cells
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DOI：
10.1016/j.plantsci.2009.06.014
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发表时间：
2009-10-01
期刊：
影响因子：
5.2
通讯作者：
Pozueta, Javier
中科院分区：
文献类型：
--
作者：
Etxeberria, Ed;Gonzalez, Pedro;Pozueta, Javier
真核生物细胞内囊泡的运输因货物分子和靶细胞器的性质不同而不同，并通过错综复杂的内部内体隔室网络进行。然而，液相内吞作用(FPE)的途径，即来自质外体的外部溶质通过质膜产生的小泡内化，尽管有一些迹象表明有直接运输到液泡的途径，但仍然没有得到解决。为了验证这一假说，我们使用了膜不通透性的钠依赖荧光标记CORO-Na、荧光膜标记FM4-和激光共聚焦扫描显微镜。甜柠檬果汁细胞的原生质体在无钠溶液、FM4-、Coro-Na和200 mM蔗糖中孵育时，明显有两种不同类型的标记小泡。一组囊泡(直径约1微米)被CORO-Na强烈标记，而FM4-标记较少，而第二类1-7微米结构出现了FM4-专属标记。这些数据证明了植物细胞中两条内吞途径的平行功能。在一个系统中，一组小的内吞囊泡与内体合并，而另一组单独的小泡融合形成独立于内体的更大的囊泡。虽然这两个小泡系统最终可能有助于溶质到达液泡，但考虑到它们的大小(1-7微米)，以及先前观察到的从质膜突出并与液泡合并的内吞小泡的形成，我们得出结论，这些小泡构成了初级FPE小泡系统。(C)2009爱思唯尔爱尔兰有限公司。保留所有权利。
Intracellular trafficking of endocytic vesicles in eukaryotes varies with the nature of the cargo molecules and the targeted organelle, and proceeds through an intricate network of internal endosomal compartments. However, the path for fluid-phase endocytosis (FPE), the internalization of external solutes from the apoplast via plasmalemma generated vesicles, remains unresolved despite some indication of a direct transport route to the vacuole. To test this hypothesis, we made use of the membrane-impermeable Na-dependent fluorescent marker Coro-Na in combination with the fluorescent membrane marker FM 4-64 and confocal laser scanning microscopy. When protoplasts from sweet lime juice cells were incubated in Na-free solution, FM 4-64, Coro-Na, and 200 mM sucrose, two distinct types of labeled vesicles were evident. A set of vesicles (similar to 1 mu m in diameter) was intensely labeled with Coro-Na and to a lesser extent with FM 4-64, whereas the second type of 1-7 mu m structures appeared exclusively labeled with FM 4-64. These data demonstrate the parallel functioning of two endocytic pathways in plant cells. In one system, a set of small endocytic vesicles merge with the endosome, whereas a separate set of vesicles fuse to form larger vesicles independent from the endosome. Although it is likely that both vesicle systems eventually contribute to solutes reaching the vacuole, given their size (1-7 mu m), and based on previous observations of endocytic vesicle formation protruding from the plasmalemma and merging with the vacuole, we conclude that these latter vesicles constitute the primary FPE vesicle system. (C) 2009 Elsevier Ireland Ltd. All rights reserved.