An indirect role for upstream stimulatory factor in glucose-mediated induction of pyruvate kinase and S14 gene expression.
An indirect role for upstream stimulatory factor in glucose-mediated induction of pyruvate kinase and S14 gene expression.
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上游刺激因子在葡萄糖介导的丙酮酸激酶和 S14 基因表达诱导中的间接作用。
DOI：
10.1023/a:1007006429041
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发表时间：
2000
影响因子：
4.3
通讯作者：
Olson,LK
中科院分区：
文献类型：
--
作者：
Kaytor,EN;Qian,J;Towle,HC;Olson,LK
L型丙酮酸激酶（L-PK）和S14基因的转录在肝细胞中响应于增加的葡萄糖代谢而被诱导。负责葡萄糖诱导的这些基因的调控序列已被映射到相关的启动子中含有E盒的基序。类似地，响应于升高的葡萄糖，L-PK启动子活性在分化的胰腺β细胞系INS-1中被刺激。通过突变分析，我们证明了INS-1细胞中葡萄糖诱导的序列要求与肝细胞中观察到的序列要求相同，表明相同的转录因子负责调节两种细胞类型中的L-PK表达。与这两种基因的葡萄糖调节序列结合的一种核因子是上游刺激因子（USF），一种普遍存在的E盒结合蛋白。缺失USF 2基因的小鼠显示出对碳水化合物喂养的严重延迟的反应（Valletet al. [26]）。然而，这一观察并没有区分USF在这一过程中的直接和间接作用。为了进一步了解USF在葡萄糖信号传导中的可能参与，我们使用了表达USF显性阴性形式的重组腺病毒构建体。这种显性阴性可与内源性USF二聚化，并显示可抑制肝细胞和INS-1细胞中USF的DNA结合。然而，显性负性USF的表达并不阻断葡萄糖刺激肝细胞中L-PK或S14基因表达或INS-1细胞中L-PK启动子活性的能力。我们的结论是USF不通过结合S14或L-PK基因的葡萄糖调控序列发挥作用，USF在葡萄糖诱导过程中的作用是间接的。
Transcription of the L-type pyruvate kinase (L-PK) and S14genes is induced in hepatocytes in response to increased glucose metabolism. The regulatory sequences of these genes responsible for induction by glucose have been mapped to related E-box containing motifs in the promoters. Similarly, L-PK promoter activity is stimulated in a differentiated pancreatic β-cell line, INS-1, in response to elevated glucose. By mutational analysis, we demonstrate that the sequence requirements for glucose induction in the INS-1 cell are identical to those observed in the hepatocyte, suggesting that the same transcriptional factor(s) is responsible for regulation of L-PK expression in the two cell types. One nuclear factor that binds to the glucose regulatory sequences of both of these genes is the Upstream Stimulatory Factor (USF), a ubiquitous E-box binding protein. Mice deleted for the USF2 gene display a severely delayed response to carbohydrate feeding (Valletet al.[26]). This observation, however, does not differentiate between a direct and an indirect role for USF in the process. To gain further insight into the possible involvement of USF in glucose signaling, we have used a recombinant adenoviral construct that expresses a dominant negative form of USF. This dominant negative can dimerize with endogenous USF and is shown to inhibit DNA binding of USF in hepatocytes and INS-1 cells. However, expression of the dominant negative USF did not block the ability of glucose to stimulate L-PK or S14gene expression in hepatocytes or L-PK promoter activity in INS-1 cells. We conclude that USF does not act by binding to the glucose regulatory sequences of the S14or L-PK genes and the role of USF in the process of glucose induction is indirect.