Glut-4 is translocated to both caveolae and non-caveolar lipid rafts, but is partially internalized through caveolae in insulin-stimulated adipocytes

Caveolae 和 non-caveolar 类脂化合物椽子是膜 lipidmicrodomains 的二种类型在 adipocytes 在刺激胰岛素的葡萄糖举起起重要作用。为了在这查明他们的特定的功能，处理， caveolae 被 caveolin-1 RNAinterference 切除。在 Cav-1 RNAi adipocytes，也不刺激胰岛素的葡萄糖举起也不 Glut-4 (葡萄糖 transporter 4 ) translocation 到膜类脂化合物微领域被脱离 ofcaveolae 影响。与一个修改蔗糖密度坡度， caveolae 和 non-caveolar 类脂化合物椽子能被分开。在野类型的 3T3-L1 adipocytes， Glut-4 被发现是进 bothcaveolae 和 non-caveolar 类脂化合物椽子的 translocated。在 Cav-1 RNAi adipocytes，然而， Glut-4 在 non-caveolar 类脂化合物椽子主要是局部性的。在胰岛素的移动以后， caveolae 局部性的 Glut-4was 比 non-caveolar 类脂化合物快使内在化联系木排的 Glut-4。从质膜的成为主观 ofGlut-4 显著地在 Cav-1 RNAi adipocytes 被减少。这些结果建议那刺激胰岛素的 Glut-4 translocation 和葡萄糖举起是 caveolae-independentevents。Caveolae 玩在从在胰岛素的移动以后的质膜的 Glut-4 的成为主观的一个角色。

Caveolae and non-caveolar lipid rafts are two types of membrane lipid microdomains that play important roles in insulin-stimulated glucose uptake in adipocytes. In order to ascertain their specific functions in this process, caveolae were ablated by caveolin-1 RNA interference. In Cav-1 RNAi adipocytes, neither insulin-stimulated glucose uptake nor Glut-4 （glucose transporter 4） translocation to membrane lipid microdomains was affected by the ablation of caveolae. With a modified sucrose density gradient, caveolae and non-caveolar lipid rafts could be separated. In the wild-type 3T3- L l adipocytes, Glut-4 was found to be translocated into both caveolae and non-caveolar lipid rafts. However, in Cav1 RNAi adipocytes, Glut-4 was localized predominantly in non-caveolar lipid rafts. After the removal of insulin, caveolaelocalized Glut-4 was internalized faster than non-caveolar lipid raft-associated Glut-4. The internalization of Glut-4 from plasma membrane was significantly decreased in Cav-1 RNAi adipocytes. These results suggest that insulin-stimulated Glut-4 translocation and glucose uptake are caveolae-independent events. Caveolae play a role in the internalization of Glut-4 from plasma membrane after the removal of insulin.