Transcriptional regulation of the fucosyltransferase VI gene in hepatocellular carcinoma cells
Transcriptional regulation of the fucosyltransferase VI gene in hepatocellular carcinoma cells
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DOI：
10.1007/s10719-008-9114-z
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发表时间：
2008-04-01
影响因子：
3
通讯作者：
Matsumoto, Kojiro
中科院分区：
文献类型：
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作者：
Higai, Koji;Miyazaki, Noriko;Matsumoto, Kojiro
α 1，3-岩藻糖基转移酶VI（FUT VI）蛋白是上皮细胞中合成唾液酸刘易斯X和刘易斯X的关键酶。尽管它的重要性，如何FUT VI的表达进行调节，以前没有阐明。在这项工作中，我们研究了肝细胞癌HepG 2细胞中FUT VI基因的转录调控。cDNA末端的5 ′-快速扩增分析揭示了FUT VI在HepG 2细胞中的转录起始位点，其位于人类转录起始位点数据库中登记的位置下游的+65和+278个核苷酸（nt）处。我们使用荧光素酶报告基因测定确定了HepG 2细胞中FUT VI的启动子区。当-186至-156和-56至-19 nt区域缺失时，位于转录起始位点5 '上游的构建体的启动子活性降低。这些区域的定点突变显示，两个肝细胞核因子-4 α（HNF-4 α）和一个八聚体结合转录因子-1（Oct-1）结合位点是FUT VI转录所必需的。此外，瞬时过表达HNF-4 α而非Oct-1增强了HuH-7细胞中FUT VI启动子活性和FUT VI mRNA水平。这些结果表明，FUT VI转录起始位点的5 '侧翼区中的两个限定区域对于HepG 2细胞中的FUT VI转录是关键的。
The alpha 1,3-fucosyltransferase VI (FUT VI) protein is a key enzyme for synthesis of sialyl Lewis X and Lewis X in epithelial cells. Despite its importance, how FUT VI expression is regulated has not previously been elucidated. In this work, we examined transcriptional regulation of the FUT VI gene in hepatocellular carcinoma HepG2 cells. 5'-Rapid amplification of cDNA ends analysis revealed transcription start sites of FUT VI in HepG2 cells at +65 and +278 nucleotides (nt) downstream of the position registered in the Data Base of Human Transcription Start Sites. We determined promoter regions for FUT VI in HepG2 cells using a luciferase reporter gene assay. The promoter activities of constructs located 5'-upstream of the transcription start site decreased when the -186 to -156 and -56 to -19 nt regions were deleted. Site-directed mutagenesis of these regions revealed that two hepatocyte nuclear factor-4 alpha (HNF-4 alpha) and one octamer binding transcription factor-1 (Oct-1) binding sites are essential for FUT VI transcription. Furthermore, transient over-expression of HNF-4 alpha but not Oct-1 enhanced both FUT VI promoter activities and FUT VI mRNA levels in HuH-7 cells. These results suggest that two defined regions in the 5'-flanking region of the FUT VI transcription start site are critical for FUT VI transcription in HepG2 cells.