Rab13 mediates the continuous endocytic recycling of occludin to the cell surface
Rab13 mediates the continuous endocytic recycling of occludin to the cell surface
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DOI：
10.1074/jbc.m406906200
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发表时间：
2005-01-21
影响因子：
4.8
通讯作者：
Sasaki, T
中科院分区：
文献类型：
--
作者：
Morimoto, S;Nishimura, N;Sasaki, T
在上皮形态发生过程中，粘附连接（AJs）和紧密连接（TJs）经历动态重组，而上皮极性短暂丧失和重建。虽然ARF 6介导的E-钙粘蛋白的内吞再循环已被表征并与AJs的快速重塑有关，但TJ动态重排的分子基础仍然难以捉摸。封闭蛋白和封闭蛋白是包含TJ链的整合膜蛋白，并且被认为负责建立和维持上皮极性。在这里，我们研究了occludin和claudins的细胞内运输和从细胞表面。使用细胞表面生物素化和免疫荧光，我们发现，一个池的occludin连续内吞和回收回细胞表面的成纤维细胞幼仓鼠肾细胞和上皮MTD-1A细胞。生化内吞和再循环试验表明，Rab 13显性活性突变体（Rab 13 Q67 L）抑制occludin的胞内后再循环，但不抑制MTD-1A细胞中的转铁蛋白受体和多聚免疫球蛋白受体。双免疫标记显示，一部分内吞occludin与Rab 13共定位在MTD-1A细胞。这些结果表明，Rab 13特异性地介导成纤维细胞和上皮细胞中occludin向细胞表面的连续内吞再循环。
During epithelial morphogenesis, adherens junctions (AJs) and tight junctions (TJs) undergo dynamic reorganization, whereas epithelial polarity is transiently lost and reestablished. Although ARF6-mediated endocytic recycling of E-cadherin has been characterized and implicated in the rapid remodeling of AJs, the molecular basis for the dynamic rearrangement of TJs remains elusive. Occludin and claudins are integral membrane proteins comprising TJ strands and are thought to be responsible for establishing and maintaining epithelial polarity. Here we investigated the intracellular transport of occludin and claudins to and from the cell surface. Using cell surface biotinylation and immunofluorescence, we found that a pool of occludin was continuously endocytosed and recycled back to the cell surface in both fibroblastic baby hamster kidney cells and epithelial MTD-1A cells. Biochemical endocytosis and recycling assays revealed that a Rab13 dominant active mutant (Rab13 Q67L) inhibited the postendocytic recycling of occludin, but not that of transferrin receptor and polymeric immunoglobulin receptor in MTD-1A cells. Double immunolabelings showed that a fraction of endocytosed occludin was colocalized with Rab13 in MTD-1A cells. These results suggest that Rab13 specifically mediates the continuous endocytic recycling of occludin to the cell surface in both fibroblastic and epithelial cells.