Sequential action of Ets-1 and Sp1 in the activation of the human β-1,4-galactosyltransferase v gene involved in abnormal glycosylation characteristic of cancer cells
Sequential action of Ets-1 and Sp1 in the activation of the human β-1,4-galactosyltransferase v gene involved in abnormal glycosylation characteristic of cancer cells
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DOI：
10.1074/jbc.m611862200
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发表时间：
2007-09-21
影响因子：
4.8
通讯作者：
Furukawa, Kiyoshi
中科院分区：
文献类型：
--
作者：
Sato, Takeshi;Furukawa, Kiyoshi
\恶性转化与β-1，4-半乳糖基转移酶（β-1，4-GaIT）V的基因表达增加有关，β-1，4-GaIT V有助于癌细胞特有的高度分支N-连接寡糖的生物合成。我们先前的研究表明，人β-1，4-GaIT V基因的表达受Spl调节（Sato，T.，和Furukawa，K.（2004）J.BioLChem.279，39574-39583），并且随后的研究表明基因表达也被Ets-1激活，Ets-1是癌基因的产物（Sato，T.，和Furukawa，K.等人（2005）Glycoconj. J. 22，365）。在这里，我们报告的机制β-1，4-GaIT V基因激活这些转录因子。当ets-1 cDNA转染到含有少量Ets-1的A549细胞中时，β-1，4-GaIT V的基因表达和启动子活性增加，但当显性负性ets-1 cDNA转染到含有大量Ets-1的HepG 2细胞中时，β-1，4-GaIT V的基因表达和启动子活性显著降低。使用β-1，4-GaIT V基因启动子的缺失构建体的荧光素酶测定显示，启动子区-116至+22对于Ets-1对基因的转录激活是关键的。尽管存在一个Ets-1结合位点，其中重叠的Sp1结合位点，电泳迁移率变动分析表明，该地区优先结合Sp1，而不是Ets-1。为了解决这个问题，我们研究了Ets-1对人Sp1基因的转录调控，发现在癌细胞中Sp1的基因表达和启动子活性受Ets-1的调控。对Sp1基因启动子中两个Ets-1结合位点的功能分析表明，只有Ets-1结合位点-413至-404参与Ets-1对该基因的激活。这些结果表明，Ets-1通过激活癌细胞中的Sp1基因来增强β-1，4-GaIT V基因的表达。
\Malignant transformation is associated with increased gene expression of beta-1,4-galactosyltransferase (beta-1,4-GaIT) V, which contributes to the biosynthesis of highly branched N-linked oligosaccharides characteristic of cancer cells. Our previous study showed that expression of the human beta-1,4-GaIT V gene is regulated by Spl (Sato, T., and Furukawa, K. (2004) J. BioL Chem. 279, 39574-39583), and a subsequent study showed that the gene expression is also activated by Ets-1, a product of the oncogene (Sato, T., and Furukawa, K. (2005) Glycoconj. J. 22, 365). Herein we report the mechanism of beta-1,4-GaIT V gene activation by these transcription factors. The gene expression and promoter activity of beta-1,4-GaIT V increased when the ets-1 cDNA was transfected into A549 cells, which contain a small amount of Ets-1, but decreased dramatically when the dominant-negative ets-1 cDNA was transfected into HepG2 cells, which contain a large amount of Ets-1. Luciferase assays using deletion constructs of the beta-1,4-GaIT V gene promoter showed that promoter region - 116 to + 22 is critical for the transcriptional activation of the gene by Ets-1. Despite the presence of one Ets-1-binding site, which overlapped the Sp1-binding site, electrophoretic mobility shift assays showed that the region bound preferentially to Spl rather than to Ets-1. To solve this problem, we examined the transcriptional regulation of the human Spl gene by Ets-1 and found that the gene expression and promoter activity of Sp1 are regulated by Ets-1 in cancer cells. Functional analyses of two Ets-1-binding sites in the Sp1 gene promoter showed that only Ets-1-binding site -413 to -404 is involved in the activation of the gene by Ets-1. These results indicate that Ets-1 enhances expression of the beta-1,4-GaIT V gene through activation of the Sp1 gene in cancer cells.