Glucose regulation of mouse S14 gene expression in hepatocytes -: Involvement of a novel transcription factor complex
Glucose regulation of mouse S14 gene expression in hepatocytes -: Involvement of a novel transcription factor complex
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DOI：
10.1074/jbc.275.7.5200
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发表时间：
2000-02-18
影响因子：
4.8
通讯作者：
Towle, HC
中科院分区：
文献类型：
--
作者：
Koo, SH;Towle, HC
编码脂肪生成所需酶的基因的转录在肝细胞中被诱导以响应升高的葡萄糖代谢。我们之前已经绘制了大鼠肝型丙酮酸激酶 (L-PK) 和 S-14 基因的碳水化合物反应元件 (ChoRE)，并发现它们具有显着的序列相似性。然而，由于难以识别与这些 ChoRE 结合的关键因子，阐明这一信号通路的进展受到了阻碍。为了进一步了解碳水化合物反应性转录因子的性质，在原代肝细胞中检查了小鼠 S-14 基因的葡萄糖调节序列。发现三个元件对于支持葡萄糖反应至关重要：-1522和-1494之间的甲状腺激素反应元件、-1421和-1392之间的辅助因子位点以及-1450和-1425之间的ChoRE。其中，只有辅助因子位点在大鼠和小鼠S-14基因之间是保守的。对 ChoRE 序列的研究表明，两个半 E 盒基序对于葡萄糖反应至关重要。电泳迁移率变动分析揭示了小鼠 S-14 ChoRE 和肝核蛋白之间形成的复合物。该复合物也是由来自大鼠 S-14 和 L-PK 基因的 ChoRE 形成的，但不是由这些不支持葡萄糖反应的位点的突变体形成的。这些结果表明存在一种新型转录因子复合物，可介导 S-14 和 L-PK 基因的葡萄糖调节转录。
Transcription of genes encoding enzymes required for lipogenesis is induced in hepatocytes in response to elevated glucose metabolism. We have previously mapped the carbohydrate-response elements (ChoREs) of the rat liver-type pyruvate kinase (L-PK) and S-14 genes and found them to share significant sequence similarity. However, progress in unraveling this signaling pathway has been hampered due to the difficulty in identifying the key factor(s) that bind to these ChoREs. To gain further insight into the nature of the carbohydrate-responsive transcription factor, the glucose regulatory sequences from the mouse S-14 gene were examined in primary hepatocytes. Three elements were found to be essential for supporting the glucose response: a thyroid hormone-response element between -1522 and -1494, an accessory factor site between -1421 and -1392, and the ChoRE between -1450 and -1425, Of these, only the accessory factor site was conserved between the rat and mouse S-14 genes. Investigation of the ChoRE sequence indicated that two half E box motifs are critical for the response to glucose. Electrophoretic mobility shift assays revealed a complex formed between the mouse S-14 ChoRE and liver nuclear proteins. This complex was also formed by ChoREs from the rat S-14 and L-PK genes but not by mutants of these sites that are inactive in supporting the glucose response. These results suggest the presence of a novel transcription factor complex that mediates the glucose-regulated transcription of S-14 and L-PK genes.