Control of Glut1 promoter activity under basal conditions and in response to hyperosmolarity: role of Sp1
Control of Glut1 promoter activity under basal conditions and in response to hyperosmolarity: role of Sp1
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DOI：
10.1152/ajpcell.00089.2005
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发表时间：
2006-02-01
影响因子：
5.5
通讯作者：
Ismail-Beigi, F
中科院分区：
文献类型：
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作者：
Hwang, DY;Ismail-Beigi, F
我们之前发现（Hwang DY and Ismail-Beigi F. Am J Physiol Cell Physiol 281: C1365-C1372, 2001）大鼠近端葡萄糖转运体（Glut）1启动子的一个44 bp的富含gc的片段，位于-104至-61，是Glut1基因基础转录所必需的。通过缺失和突变分析以及转染的报告基因结构的表达，我们在本研究中报道，启动子这段Sp1位点的突变导致基础启动子活性显著降低（类似于4倍）。位于Sp1位点和第二个下游富gc区（-71至-51）的双突变不会导致启动子活性进一步降低。凝胶移位和超移位实验证实了Sp1位点的重要性。暴露于曲古斯汀A的细胞导致内源性Glut1的表达增加，以及转染的野生型构建体。最后，Sp1位点的存在被发现是启动子对高渗透压的积极反应所必需的。我们得出结论，Sp1位点位于大鼠Glut1启动子的近端，对于Glut1基因的基础表达及其对高渗的反应是必要和充分的。
We previously identified (Hwang DY and Ismail-Beigi F. Am J Physiol Cell Physiol 281: C1365-C1372, 2001) a 44-bp GC-rich segment of the rat proximal glucose transporter (Glut)1 promoter, located at -104 to -61, as necessary for basal transcription of the Glut1 gene. Using deletion and mutational analysis and expression of transfected reporter constructs, we report in the present study that mutation of the Sp1 site located within this segment of the promoter leads to a marked (similar to 4-fold) decrease in basal promoter activity. Double mutations located in the Sp1 site and in a second downstream GC-rich region (-71 to -51) did not cause a further decrease in promoter activity. Gel shift and supershift assays verified the importance of the Sp1 site. Exposure of cells to trichostatin A resulted in increased expression of the endogenous Glut1 as well as the transfected wild-type construct. Finally, the presence of the Sp1 site was found to be essential for the positive response of the promoter to hyperosmolarity. We conclude that the consensus Sp1 site located in the rat proximal Glut1 promoter is necessary and sufficient for basal expression of the Glut1 gene, as well as for its response to hyperosmolarity.