Role of BIG2, a Guanine-Nucleotide Exchanging factor for ADP-Ribosylation Factors, in Insulin-Regulated Glucose Transporter Translocation

我们在这里表明，BIG2在基底细胞和胰岛素刺激的脂肪细胞内体腔室中Glut4囊泡的形成中起重要作用。在3T3-L1脂肪细胞中，通过RNA干扰敲低BIG2导致胰岛素刺激的Glut4转运到质膜的不足。通过亚细胞分离分析Glut4的基本分布。结果表明，在big2敲低的细胞中，glut4囊泡的形成受到强烈抑制。在这里，我们使用了glut4囊泡的体外重构，以证明这些glut4囊泡是由内体膜以big2依赖的方式形成的。内源性BIG2的减少抑制了由未刺激和胰岛素刺激的脂肪细胞制备的内体腔室中Glut4囊泡的体外形成。

We here show that BIG2 plays an important role in a formation of Glut4 vesicles from endosomal compartment in both basal and insulin-stimulated adipocytes. In 3T3-L1 adipocytes, knockdown of BIG2 by RNA interference leaded to insufficient insulin-stimulated Glut4 translocation to the plasma membrane. The basal distribution of Glut4 was analyzed by subcellular fractionation. It was shown that the formation of Glut4-vesicles in the BIG2-knockdown cells was strongly repressed. Here, we used an in vitro reconstitution of Glut4-vesicles in order to demonstrate that these Glut4-vesicles are formed from endosomal membranes in a BIG2-dependent manner. Reducing endogenous BIG2 inhibited in vitro formation of Glut4 vesicles from the endosomal compartment prepared from not only unstimulated but insulin-stimulated adipocytes.