MOUSE INSULIN-RESPONSIVE GLUCOSE TRANSPORTER GENE - CHARACTERIZATION OF THE GENE AND TRANSACTIVATION BY THE CCAAT ENHANCER BINDING-PROTEIN
MOUSE INSULIN-RESPONSIVE GLUCOSE TRANSPORTER GENE - CHARACTERIZATION OF THE GENE AND TRANSACTIVATION BY THE CCAAT ENHANCER BINDING-PROTEIN
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DOI：
10.1073/pnas.87.1.251
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发表时间：
1990-01-01
影响因子：
11.1
通讯作者：
LANE, MD
中科院分区：
文献类型：
--
作者：
KAESTNER, KH;CHRISTY, RJ;LANE, MD
脂肪组织、骨骼肌和心肌表现为胰岛素刺激的葡萄糖摄取，表达一种特定的胰岛素反应性葡萄糖转运体。此前，从小鼠3T3-L1脂肪细胞文库中分离出了编码该蛋白的cDNA(GT2)并进行了测序。在这里，我们报告了命名为GLUT4的相应小鼠基因的分离和鉴定。GLUT4基因全长7kb，由11个外显子和10个内含子组成。转录起始点位于起始蛋氨酸密码子的上游180个核苷酸。GLUT4启动子含有核转录因子Sp1的四个潜在结合部位和一个CCAAT盒。用未分化和分化的3T3-L1细胞的核提取物对GLUT4启动子进行DNase I足迹研究表明，分化特异性核因子结合在相对于转录起始位置的-258位区域。纯化的CCAAT/增强子结合蛋白(C/EBP)被发现结合在相同的位置。将含有C/EBP结合位点的GLUT4启动子-氯霉素乙酰转移酶基因与C/EBP表达载体瞬时共转染3T3-L1前脂肪细胞，发现C/EBP反式激活GLUT4启动子。我们认为C/EBP在胰岛素反应性葡萄糖转运蛋白基因的组织特异性和代谢调节中起着重要作用。
Adipose tissue and skeletal and heart muscle, which exhibit insulin-stimulated glucose uptake, express a specific, insulin-responsive glucose transporter. Previously, a cDNA (GT2) encoding this protein was isolated from a mouse 3T3-L1 adipocyte library and was sequenced. Here we report the isolation and characterization of the corresponding mouse gene designated GLUT4. The GLUT4 gene spans 7 kilobases and consists of 11 exons and 10 introns. The start site of transcription was mapped 180 nucleotides upstream of the initial methionine codon. The GLUT4 promoter contains four potential binding sites for the nuclear transcription factor Sp1 as well as a CCAAT box. DNase I footprinting of the GLUT4 promoter with nuclear extracts from undifferentiated and differentiated 3T3-L1 cells revealed that a differentiation-specific nuclear factor binds in the region at position -258 relative to the start site of transcription. Purified CCAAT/enhancer binding protein (C/EBP) was found to bind at the same position. Transient cotransfection into 3T3-L1 preadipocytes of a GLUT4 promoter-chloramphenicol acetyltransferase gene construct that contains the C/EBP binding site, together with a C/EBP expression vector, revealed that C/EBP trans-activates the GLUT4 promoter. We suggest that C/EBP plays an important role in tissue-specific, as well as metabolic, regulation of the insulin-responsive glucose transporter gene.