GATA-6 stimulates a cell line-specific activation element in the human lactase promoter.
GATA-6 stimulates a cell line-specific activation element in the human lactase promoter.
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GATA-6 刺激人乳糖酶启动子中的细胞系特异性激活元件。
DOI：
10.1152/ajpgi.1998.274.2.g314
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Avigan,MI
中科院分区：
文献类型：
--
作者：
Fitzgerald,K;Bazar,L;Avigan,MI
乳糖酶根皮苷水解酶（LPH）的合成仅限于分化的小肠上皮细胞，并在发育过程中受到高度调节。LPH启动子片段融合荧光素酶转染Caco-2细胞，一个线，独特地表达LPH mRNA的表达分析，映射一个18碱基对（bp）的片段100 bp的转录起始位点上游的反式激活所需的。值得注意的是，LPH上游元件（LUE）在LPH mRNA不存在的人肠和非肠细胞系中没有刺激活性。序列特异性DNA-核蛋白复合物的电泳分析表明存在Caco-2细胞特异性蛋白（CCP），这在LPH非生产细胞系中一致缺失。LUE的突变分析表明，包含在加塔共有基序内的碱基对于CCP结合和从LPH启动子转录都是至关重要的。Caco-2细胞以细胞系特异性方式表达高水平的加塔-6 mRNA，表明加塔-6是与LUE复合的CCP。当由质粒表达时，加塔-6反式激活LPH启动子。这种刺激被加塔共有基序中的突变以及侧翼下游元件中的突变所废除。这些研究与肠加塔结合蛋白在LPH启动子的细胞类型特异性反式激活中的重要作用一致。
Lactase-phlorizin hydrolase (LPH) synthesis is restricted to differentiated small intestinal enterocytes and is highly regulated during development. Analysis of expression of LPH promoter segments fused with luciferase transfected in Caco-2 cells, a line that uniquely expresses LPH mRNA, mapped an 18-base pair (bp) segment 100 bp upstream of the transcription start site that is required for transactivation. Remarkably, the LPH upstream element (LUE) has no stimulatory activity in both human intestinal and nonintestinal lines in which LPH mRNA is absent. Electrophoretic analysis of sequence-specific DNA-nuclear protein complexes demonstrated the presence of a Caco-2 cell-specific protein(s) (CCP), which is uniformly absent in LPH nonproducer cell lines. Mutational analysis of the LUE demonstrated that bases contained within a GATA consensus motif are critical for both CCP binding and transcription from the LPH promoter. Caco-2 cells express high levels of GATA-6 mRNA in a cell line- specific manner, suggesting that GATA-6 is a CCP that complexes with the LUE. When expressed by a plasmid, GATA-6 transactivated the LPH promoter. The stimulation was abrogated with mutations in the GATA consensus motif as well as mutations in a flanking downstream element. These studies are consistent with an important role of an intestinal GATA binding protein in cell type-specific transactivation of the LPH promoter.