Transcriptional repression of the GLUT4 and C/EBP genes in 3T3-L1 adipocytes by tumor necrosis factor-alpha.
Transcriptional repression of the GLUT4 and C/EBP genes in 3T3-L1 adipocytes by tumor necrosis factor-alpha.
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DOI：
10.1016/s0021-9258(18)54714-1
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发表时间：
1991-11
期刊：
影响因子：
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通讯作者：
Jacqueline M. Stephens;P. Pekala
中科院分区：
文献类型：
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作者：
Jacqueline M. Stephens;P. Pekala
将完全分化的3 T3-L1脂肪细胞长期暴露于5 nM肿瘤坏死因子-α（TNF）。这导致了基于胰岛素不能刺激己糖摄取的胰岛素抵抗的发展。分离的膜组分中葡萄糖转运蛋白的Western印迹分析表明，在用TNF长期处理的细胞中，GLUT 4蛋白（胰岛素响应性葡萄糖转运蛋白）完全耗尽。GLUT 1蛋白（生长相关葡萄糖转运蛋白）的质膜含量在对照和TNF处理的细胞中相似;然而，TNF处理后细胞内膜隔室的GLUT 1含量显著降低。与年龄匹配的对照组相比，连续暴露于TNF导致GLUT 4和422（aP 2，一种脂质结合蛋白）基因的mRNA含量降低85-90%，而胰岛素受体mRNA水平降低至少50%。在此之前，C/EBP（一种控制GLUT 4和422表达的转录因子）的mRNA积累显著减少。这些观察结果的特异性通过长期TNF处理对β-肌动蛋白或脂蛋白脂肪酶mRNA含量缺乏影响来证明。根据转录运行试验的结果，GLUT 4和C/EBP mRNA含量的降低被判定为至少部分在转录水平上受到调节。因此，由于GLUT 4表达的抑制以及GLUT 1的细胞内含量的降低，出现了对胰岛素的反应的缺乏。
Fully differentiated 3T3-L1 adipocytes were chronically exposed to 5 nM tumor necrosis factor-alpha (TNF). This resulted in the development of an insulin resistance based on the inability of insulin to stimulate hexose uptake. Western blot analysis for glucose transporter protein in isolated membrane fractions indicated a total depletion of GLUT4 protein (insulin-responsive glucose transporter) in cells chronically treated with TNF. Plasma membrane content of GLUT1 protein (growth-related glucose transporter) was similar in both control and TNF-treated cells; however, the GLUT1 content of the intracellular membrane compartment had decreased markedly after TNF treatment. Continuous exposure to TNF resulted in an 85-90% decrease in the mRNA content for both GLUT4 and 422 (aP2, a lipid binding protein) genes relative to age matched controls, whereas insulin receptor mRNA levels declined by at least 50%. This was preceded by a marked decrease in mRNA accumulation for C/EBP, a transcription factor proposed to control expression of both GLUT4 and 422. The specificity of these observations was demonstrated by the lack of an effect of the chronic TNF treatment on either beta-actin or lipoprotein lipase mRNA content. The decreased content of GLUT4 and C/EBP mRNA was judged to be regulated at least in part at the level of transcription, based on the results of transcription run-on assays. Thus, the lack of response to insulin appeared due to a suppression of GLUT4 expression as well as a decreased intracellular content of GLUT1.