Sp1 and Sp3 Are the Transcription Activators of Human ek1 Promoter in TSA-Treated Human Colon Carcinoma Cells.
Sp1 and Sp3 Are the Transcription Activators of Human ek1 Promoter in TSA-Treated Human Colon Carcinoma Cells.
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DOI：
10.1371/journal.pone.0147886
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Few LL
中科院分区：
文献类型：
--
作者：
Kuan CS;See Too WC;Few LL
乙醇胺激酶 (EK) 催化乙醇胺的磷酸化，这是磷脂酰乙醇胺 (PE) 生物合成的 CDP-乙醇胺途径的第一步。人类 EK 以 EK1、EK2α 和 EK2β 同工型形式存在，由两个独立的基因（名为 ek1 和 ek2）编码。 EK 活性受到致癌物和癌基因的刺激，表明 EK 参与了致癌过程。目前，人们对EK通过内源或外源信号进行转录调控知之甚少，并且ek基因启动子也从未被研究过。在本报告中，我们绘制了人类 ek1 启动子中的重要调控区域。 5’缺失分析和定点诱变鉴定出位置 (-40/-31) 的 Sp 位点，该位点对于该基因的基础转录至关重要。用组蛋白脱乙酰酶抑制剂曲古抑菌素 A (TSA) 处理 HCT116 细胞，通过 Sp(-40/-31) 位点显着上调 ek1 启动子活性，并增加 ek1 的内源表达。染色质免疫沉淀分析显示，TSA 增加了 HCT116 细胞中 Sp1、Sp3 和 RNA 聚合酶 II 与 ek1 启动子的结合。 TSA 对 ek1 启动子活性的影响具有细胞系特异性，因为 TSA 处理不影响 HepG2 细胞中的 ek1 启动子活性。总之，我们表明 Sp1 和 Sp3 不仅对于 ek1 基因的基础转录至关重要，它们对 ek1 启动子上靶位点的可及性还受到组蛋白修饰以细胞系依赖性方式的调节。
Ethanolamine kinase (EK) catalyzes the phosphorylation of ethanolamine, the first step in the CDP-ethanolamine pathway for the biosynthesis of phosphatidylethanolamine (PE). Human EK exists as EK1, EK2α and EK2β isoforms, encoded by two separate genes, named ek1 and ek2. EK activity is stimulated by carcinogens and oncogenes, suggesting the involvement of EK in carcinogenesis. Currently, little is known about EK transcriptional regulation by endogenous or exogenous signals, and the ek gene promoter has never been studied. In this report, we mapped the important regulatory regions in the human ek1 promoter. 5’ deletion analysis and site-directed mutagenesis identified a Sp site at position (-40/-31) that was essential for the basal transcription of this gene. Treatment of HCT116 cells with trichostatin A (TSA), a histone deacetylase inhibitor, significantly upregulated the ek1 promoter activity through the Sp(-40/-31) site and increased the endogenous expression of ek1. Chromatin immunoprecipitation assay revealed that TSA increased the binding of Sp1, Sp3 and RNA polymerase II to the ek1 promoter in HCT116 cells. The effect of TSA on ek1 promoter activity was cell-line specific as TSA treatment did not affect ek1 promoter activity in HepG2 cells. In conclusion, we showed that Sp1 and Sp3 are not only essential for the basal transcription of the ek1 gene, their accessibility to the target site on the ek1 promoter is regulated by histone protein modification in a cell line dependent manner.