A Glut4-vesicle marker protein, insulin-responsive aminopeptidase, is localized in a novel vesicular compartment in PC12 cells
A Glut4-vesicle marker protein, insulin-responsive aminopeptidase, is localized in a novel vesicular compartment in PC12 cells
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DOI：
10.1034/j.1600-0854.2001.20807.x
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发表时间：
2001-08-01
期刊：
影响因子：
4.5
通讯作者：
Kandror, KV
中科院分区：
文献类型：
--
作者：
Thoidis, G;Kandror, KV
含Glut 4的囊泡代表胰岛素敏感性脂肪和骨骼肌细胞中受调节的再循环区室，其性质和起源尚未完全了解。除了Glut 4本身之外，这些囊泡还将许多蛋白质区室化，其中至少一种蛋白质，胰岛素响应性氨肽酶或IRAP，与Glut 4在胰岛素敏感组织中完全共定位。然而，与Glut 4不同，IRAP在多种其他组织和细胞系中表达。在这里，我们探讨了IRAP在大鼠嗜铬细胞瘤细胞系PC 12的细胞内定位。我们发现，这种蛋白质存在于一个独特的人口缓慢回收轻囊泡。通过梯度离心、免疫吸附和双重免疫荧光染色，这些囊泡不同于含转铁蛋白的内体、小突触囊泡和分泌颗粒，因此可能代表PC 12细胞中的一个新的隔室。在PC 12细胞中瞬时表达的Glut 4-GFP嵌合体靶向含IRAP的囊泡，表明Glut 4和IRAP的共靶向对脂肪细胞和肌细胞不是特异性的，但在外源细胞类型中是忠实的。我们认为，PC 12细胞可能拥有一种新型的囊泡载体，可能代表Glut 4-囊泡的同源物。
Glut4-containing vesicles represent a regulated recycling compartment in insulin-sensitive fat and skeletal muscle cells, the nature and origin of which are not fully understood. In addition to Glut4 itself, these vesicles compartmentalize a number of proteins, at least one of which, insulin-responsive aminopeptidase, or IRAP, is completely colocalized with Glut4 in insulin-sensitive tissues. However, unlike Glut4, IRAP is expressed in a variety of other tissues and cell lines. Here, we explored the intracellular localization of IRAP in the rat pheochromocytoma cell line PC12. We found that this protein is present in a distinct population of slowly recycling light vesicles. By gradient centrifugations, immunoadsorption and double immunofluorescent staining, these vesicles are different from transferrin-containing endosomes, small synaptic vesicles and secretory granules and may thus represent a novel compartment in PC12 cells. Glut4-GFP chimera transiently expressed in PC12 cells is targeted to IRAP-containing vesicles indicating that cotargeting of Glut4 and IRAP is not specific for adipocytes and myocytes, but is faithful in a foreign cell type. We suggest that PC12 cells may possess a novel type of a vesicular carrier that may represent the homolog of Glut4-vesicles.