Ishihara H, Asano T, Tsukuda K, Katagiri H, Inukai K, Anai M, Yazaki Y, Miyazaki J, Kikuchi M, Oka Y
Institute for Adult Diseases, Asahi Life Foundation, Tokyo, Japan.
Am J Physiol. 1995 Nov;269(5 Pt 1):E897-902. doi: 10.1152/ajpendo.1995.269.5.E897.
Accumulated evidence suggests that GLUT-2, in addition to its role in glucose transport, may also have other functions in glucose-stimulated insulin secretion. As a first step in addressing this possibility, we have engineered MIN6 cells overexpressing human GLUT-2 by transfection with human GLUT-2 cDNA. Stable transformants harboring human GLUT-2 cDNA exhibited an approximately twofold increase in 3-O-methyl-D-glucose uptake at 0.5 and 15 mM. Glucokinase activity or glucose utilization measured by conversion of [5-3H]glucose to [3H]H2O was not, however, altered in the MIN6 cells overexpressing human GLUT-2. Furthermore, glucose-stimulated insulin secretion was not affected by over-expression of human GLUT-2. An abundance of GLUT-2, therefore, does not correlate with the glucose responsiveness of cells in which glycolysis is regulated at the glucose phosphorylating step. These data suggest that GLUT-2 by itself does not have significant functions other than its role in glucose transport in glucose sensing by MIN6 cells.
越来越多的证据表明，葡萄糖转运蛋白2（GLUT-2）除了在葡萄糖转运中发挥作用外，在葡萄糖刺激的胰岛素分泌中可能还具有其他功能。作为探讨这种可能性的第一步，我们通过用人类GLUT-2 cDNA转染构建了过表达人类GLUT-2的MIN6细胞。携带人类GLUT-2 cDNA的稳定转化体在0.5 mM和15 mM时3-O-甲基-D-葡萄糖摄取量增加了约两倍。然而，过表达人类GLUT-2的MIN6细胞中，通过将[5-3H]葡萄糖转化为[3H]H2O测量的葡萄糖激酶活性或葡萄糖利用率并未改变。此外，葡萄糖刺激的胰岛素分泌不受人类GLUT-2过表达的影响。因此，GLUT-2的丰度与在葡萄糖磷酸化步骤调节糖酵解的细胞的葡萄糖反应性无关。这些数据表明，在MIN6细胞的葡萄糖感应中，GLUT-2自身除了在葡萄糖转运中的作用外没有显著功能。
