Chicken ovalbumin upstream promoter-transcription factor II, a new partner of the glucose response element of the L-type pyruvate kinase gene, acts as an inhibitor of the glucose response
Chicken ovalbumin upstream promoter-transcription factor II, a new partner of the glucose response element of the L-type pyruvate kinase gene, acts as an inhibitor of the glucose response
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DOI：
10.1074/jbc.274.40.28385
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发表时间：
1999-10-01
影响因子：
4.8
通讯作者：
Vasseur-Cognet, M
中科院分区：
文献类型：
--
作者：
Lou, DQ;Tannour, M;Vasseur-Cognet, M
L型丙酮酸激酶（L-PK）基因的转录在胰岛素存在下由葡萄糖诱导，并通过环AMP被胰高血糖素抑制。负责介导葡萄糖和环AMP反应的DNA调节序列，称为葡萄糖反应元件（GlRE），由两个简并的E盒组成，间隔5个碱基对，并能够结合碱性螺旋-环-螺旋/亮氨酸拉链蛋白，特别是上游刺激因子（USF）。从离体和体内实验来看，似乎USF是L-PK基因对葡萄糖的正确反应所必需的，但已知它们的表达和结合活性不受葡萄糖调节。在酵母中的遗传筛选使我们能够确定一种新的转录因子结合的GlRE，即鸡卵清蛋白上游启动子转录因子II（COUP-TFII），结合的COUP-TFII的GlRE被证实通过电泳迁移率变动分析，和COUP-TFII-含有复合物检测肝核提取物。COUP-TFII的丰度和结合活性似乎都不受饮食的显著调节。在足迹实验中，两个COUP-TFII结合位点重叠的E盒被检测到。COUP-TFII的过表达废除了COS细胞中人工GlRE依赖性启动子的USF依赖性反式激活和原代培养肝细胞中L-PK启动子的葡萄糖响应性。此外，突变的GlRE与增加的亲和力USF和非常低的亲和力COUP-TFII赋予了显着降低的葡萄糖反应性的L-PK启动子在肝细胞在原代培养中，通过增加活性的报告基因在低葡萄糖条件下。我们认为COUP-TFII可能是组装在L-PK基因GlRE上的葡萄糖传感器复合物的负调控组分，并且很可能也是其他葡萄糖响应基因的负调控组分。
Transcription of the L-type pyruvate kinase (L-PK) gene is induced by glucose in the presence of insulin and repressed by glucagon via cyclic AMP, The DNA regulatory sequence responsible for mediating glucose and cyclic AMP responses, called glucose response element (GlRE), consists of two degenerated E boxes spaced by 5 base pairs and is able to bind basic helix-loop-helix/leucine zipper proteins, in particular the upstream stimulatory factors (USFs), From ex vivo and in vivo experiments, it appears that USFs are required for correct response of the L-PK gene to glucose, but their expression and binding activity are not known to be regulated by glucose. A genetic screen in yeast has allowed us to identify a novel transcriptional factor binding to the GlRE, i.e. the chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII), Binding of COUP-TFII to the GlRE was confirmed by electrophoretic mobility shift assays, and COUP-TFII-containing complexes were detectable in liver nuclear extracts. Neither abundance nor binding activity of COUP-TFII appeared to be significantly regulated by diets. In footprinting experiments, two COUP-TFII-binding sites overlapping the E boxes were detected. Overexpression of COUP-TFII abrogated the USF-dependent transactivation of an artificial GlRE-dependent promoter in COS cells and the glucose responsiveness of the L-PK promoter in hepatocytes in primary culture. In addition, a mutated GlRE with increased affinity for USF and very low affinity for COUP-TFII conferred a dramatically decreased glucose responsiveness on the L-PK promoter in hepatocytes in primary culture by increasing activity of the reporter gene in low glucose condition. We propose that COUP-TFII could be a negative regulatory component of the glucose sensor complex assembled on the GlRE of the L-PK gene and most likely of other glucose-responsive genes as well.