Novel DNA-binding proteins regulate intestine-specific transcription of the sucrase-isomaltase gene.
Novel DNA-binding proteins regulate intestine-specific transcription of the sucrase-isomaltase gene.
复制标题
新型 DNA 结合蛋白调节蔗糖酶-异麦芽酶基因的肠道特异性转录。
DOI：
10.1128/mcb.12.8.3614-3627.1992
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发表时间：
1992
影响因子：
5.3
通讯作者：
Wang,W
中科院分区：
文献类型：
--
作者：
Traber,PG;Wu,GD;Wang,W
蔗糖酶-异麦芽糖酶（SI）是一种肠细胞特异性基因，在肠发育过程中和成年肠粘膜中表现出复杂的表达模式。在本报告中所描述的研究中，我们证明了肠细胞特异性转录的SI基因的调控的进化保守的启动子，延伸约180 bp的转录起始位点的上游。DNA酶I足迹分析允许鉴定SI启动子内的三个核蛋白结合位点（SIF 1、SIF 2和SIF 3 [SI足迹]），每个位点都充当肠细胞系中转录的正调控元件。SIF 1显示出结合存在于原代小鼠小肠细胞和肠细胞系（Caco-2）中的核蛋白复合物。然而，SIFl结合蛋白在各种其他上皮和非上皮细胞中不存在。体外突变实验表明，SIF 1位点是肠细胞中高水平启动子活性所需的。SIF 3元件与肠和肝核提取物形成突出的结合复合物，而来自其他上皮和非上皮细胞的核蛋白形成不同迁移率的较弱复合物。SIF 2元件以类似于SIF 3的模式结合核蛋白，并且交叉竞争研究表明SIF 2和SIF 3可能结合相同的核蛋白。两者合计，这些数据已允许识别新的DNA结合蛋白，其在调节SI基因的丝氨酸特异性转录中发挥重要作用。
Sucrase-isomaltase (SI) is an enterocyte-specific gene which exhibits a complex pattern of expression during intestinal development and in the adult intestinal mucosa. In the studies described in this report, we demonstrate that enterocyte-specific transcription of the SI gene is regulated by an evolutionarily conserved promoter that extends approximately 180 bp upstream of the transcription start site. DNase I footprint analysis allowed the identification of three nuclear protein-binding sites within the SI promoter (SIF1, SIF2, and SIF3 [SI footprint]), each of which acted as a positive regulatory element for transcription in intestinal cell lines. SIF1 was shown to bind nuclear protein complexes present in primary mouse small intestinal cells and in an intestinal cell line (Caco-2). However, SIFl-binding proteins were absent in a variety of other epithelial and nonepithelial cells. In vitro mutagenesis experiments demonstrated that the SIF1 site is required for high-level promoter activity in intestinal cells. The SIF3 element formed prominent binding complexes with intestinal and liver nuclear extracts, whereas nuclear proteins from other epithelial and nonepithelial cells formed weaker complexes of different mobilities. The SIF2 element bound nuclear proteins in a pattern similar to that of SIF3, and cross-competition studies suggested that SIF2 and SIF3 may bind the same nuclear proteins. Taken together, these data have allowed the identification of novel DNA-binding proteins that play an important role in regulating intestine-specific transcription of the SI gene.