Flotillin-1 defines a clathrin-independent endocytic pathway in mammalian cells
Flotillin-1 defines a clathrin-independent endocytic pathway in mammalian cells
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DOI：
10.1038/ncb1342
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发表时间：
2006-01-01
影响因子：
21.3
通讯作者：
Nichols, BJ
中科院分区：
文献类型：
--
作者：
Glebov, OO;Bright, NA;Nichols, BJ
先前的研究提供了哺乳动物细胞中的内吞机制的证据，该机制不同于网格蛋白包被的小凹和小窝（1-5），并且不受GT3-无效发动蛋白突变体的过表达的抑制（1- 4，6）.然而，这一机制在很大程度上是以这些负面的术语来定义的。我们应用基于铁流体的内体纯化来鉴定内体蛋白。以这种方式鉴定的蛋白质之一是flotillin- 1（也称为reggie- 2）（7，8）。在这里，我们表明，flotillin- 1驻留在点状结构内的质膜和特定的人口的内吞中间体。这些中间产物积累糖基磷脂酰肌醇（GPI）连接蛋白和霍乱毒素B亚单位（4，9）。在含有flotillin- 1的中间体中的内吞作用是网格蛋白非依赖性的。全内反射显微镜和免疫电子显微镜显示，质膜上含有flotillin- 1的区域似乎出芽进入细胞，并且与网格蛋白包被的小凹和小窝蛋白-1阳性小窝不同（10）。Flotillin- 1小干扰RNA（siRNA）抑制霍乱毒素的网格蛋白非依赖性摄取和GPI连接蛋白的内吞作用。我们认为flotillin- 1是哺乳动物细胞中不依赖网格蛋白的内吞途径的决定因子之一.
Previous studies provide evidence for an endocytic mechanism in mammalian cells that is distinct from both clathrin- coated pits and caveolae(1-5), and is not inhibited by overexpression of GTPase- null dynamin mutants(1-4,6). This mechanism, however, has been defined largely in these negative terms. We applied a ferro- fluid- based purification of endosomes to identify endosomal proteins. One of the proteins identified in this way was flotillin- 1 ( also called reggie- 2)(7,8). Here, we show that flotillin- 1 resides in punctate structures within the plasma membrane and in a specific population of endocytic intermediates. These intermediates accumulate both glycosyl phosphatidylinositol ( GPI)- linked proteins and cholera toxin B subunit(4,9). Endocytosis in flotillin- 1- containing intermediates is clathrin- independent. Total internal reflection microscopy and immuno- electron microscopy revealed that flotillin- 1-containing regions of the plasma membrane seem to bud into the cell, and are distinct from clathrin- coated pits and caveolin- 1- positive caveolae(10). Flotillin- 1 small interfering RNA ( siRNA) inhibited both clathrin- independent uptake of cholera toxin and endocytosis of a GPI- linked protein. We propose that flotillin- 1 is one determinant of a clathrin- independent endocytic pathway in mammalian cells.