STUDIES ON THE REGULATION OF THE INSULIN-SENSITIVE GLUCOSE TRANSPORTER--GLUT4

胰岛素是外周葡萄糖摄取所必需的。它引出了 胰岛素敏感的葡萄糖转运蛋白GLUT4的易位， 到脂肪细胞和肌肉细胞的质膜。慢性抬高 已知胰岛素会导致这种转运蛋白的下调， 导致胰岛素介导的葡萄糖摄取减少。事实是， 胰升糖素样肽-1(GLP-1)是一种胰岛素样激素，调节胰岛素 3T3-L1脂肪细胞中的信号传递(内分泌学135：2070-2075,1994) 提示我们研究GLP-1对GLUT4转运体的影响 在这些牢房里。似乎GLP-1可以逆转下调的调控 高浓度胰岛素对GLUT4基因表达的影响。GLP-1 还导致GLUT1的mRNA和蛋白、Glut1的水平增加 广泛分布在所有组织中。与这些结合在一起 发现，我们还发现GLUT4mRNA的下调诱导了 在与22 mM葡萄糖孵育的细胞中通过胰岛素可以被预防 降低培养液中的葡萄糖浓度。C/EBP家族 转录因子与脂肪细胞基因(如GLUT4)共表达 在3T3-L1脂肪细胞分化过程中。我们看了一下 Gadd153(编码C/EBP相关蛋白)与 缺乏功能DNA结合域)、C/EBPα和GLUT4，并发现 不同品种C/EBP和GLUT4基因表达水平的相关性研究 文化条件。然而，GADD 153的水平似乎 根据血糖水平的不同，mRNA与C/EBPα的不同 在培养基中。

Insulin is necessary for glucose uptake in the periphery. It induces the translocation of GLUT4, a specific insulin-sensitive glucose transporter, to the plasma membrane of fat cells and muscle cells. Chronic elevation of insulin has been known to cause downregulation of this transporter, leading to reduced insulin-mediated glucose uptake. The fact that glucagon-like peptide-1 (GLP-1) an incretin hormone, modulated insulin signalling in the 3T3-L1 adipocytes (Endocrinology 135:2070-2075, 1994) prompted us to investigate the effects of GLP-1 on the GLUT4 transporter in these cells. It appeared that GLP-1 could reverse the downregulation induced by high concentration of insulin on GLUT4 mRNA levels. GLP-1 also caused an increase in the levels of GLUT1 mRNA and protein, GLUt1 being widely distributed among all tissues. In conjunction with these findings, we also showed that the downregulation of GLUT4 mRNA induced by insulin in cells incubated with 22mM glucose could be prevented by reducing the glucose concentration in the medium. The C/EBP family of transcription factors is coexpressed with adipocyte genes (e.g. GLUT4) during the differentiation of 3T3-L1 adipocytes. We looked at the relationship between gadd 153 (which encodes a C/EBP-related protein that lacks a functional DNA-binding domain), C/EBP alpha and GLUT4, and found an association between the mRNA levels for C/EBP and GLUT4 in a variety of culture conditions. It appeared, however, that the levels of gadd 153 mRNA differed from that of C/EBP alpha depending on the glucose levels in the culture medium.