The homeodomain protein Cdx2 regulates lactase gene promoter activity during enterocyte differentiation
The homeodomain protein Cdx2 regulates lactase gene promoter activity during enterocyte differentiation
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DOI：
10.1016/s0016-5085(00)70420-3
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发表时间：
2000-01-01
期刊：
影响因子：
29.4
通讯作者：
Sibley, E
中科院分区：
文献类型：
--
作者：
Fang, RX;Santiago, NA;Sibley, E
背景和目的：乳糖酶是肠道二糖酶，负责消化乳糖，乳糖是牛奶中的主要碳水化合物。乳糖酶基因的转录在肠上皮细胞分化过程中被激活。我们已经表征了乳糖酶启动子和 Cdx2 之间的相互作用，Cdx2 是一种参与调节肠道发育和分化的同源域蛋白。方法：通过电泳迁移率变动分析和 Cdx2 抗体的超迁移分析与乳糖酶基因顺式元件结合的核蛋白 CE-LPH1。在用荧光素酶报告构建体和 Cdx2 表达构建体转染的细胞中测定乳糖酶启动子活性。结果：使用 CE-LPH1 进行电泳迁移率变动测定，产生需要尾部相关蛋白结合位点 TTTAC 的特定 DNA/蛋白复合物。该复合物被 Cdx2 抗体识别，并且在分化的肠上皮细胞中更为丰富，Cdx2 表达构建体能够激活由野生型启动子而非突变启动子驱动的转录，并导致内源性乳糖酶信使 RNA 增加。结论：同源域蛋白 Cdx2 与乳糖酶启动子相互作用，能够激活内源基因的转录。与之前的报道相反，Cdx2 与乳糖酶启动子的相互作用与肠上皮细胞相关差异化。这些结论与Cdx2在调节肠细胞分化中的作用一致。
Background & Aims: Lactase is the intestinal disaccharidase responsible for digestion of lactose, the predominant carbohydrate in milk. Transcription of the lactase gene is activated during enterocyte differentiation, We have characterized the interaction between the lactase promoter and Cdx2, a homeodomain protein involved in regulating intestinal development and differentiation. Methods: Nuclear protein bound to the lactase gene cis element, CE-LPH1, was analyzed by electrophoretic mobility shift assays and supershifts with Cdx2 antibody. Lactase promoter activities were assayed in cells transfected with luciferase reporter constructs and a Cdx2 expression construct. Results: Electrophoretic mobility shift assay with CE-LPH1 yields a specific DNA/protein complex that requires the caudal-related protein binding site, TTTAC. The complex is recognized by Cdx2 antibody and is more abundant in differentiated enterocytes, A Cdx2 expression construct is able to activate transcription driven by the wild-type, but not a mutated, promoter and results in increased endogenous lactase messenger RNA, Conclusions: The homeodomain protein Cdx2 interacts with the lactase promoter and is capable of activating transcription of the endogenous gene, In contrast to a previous report, Cdx2 interaction with the lactase promoter correlates with enterocyte differentiation. These conclusions are consistent with the role of Cdx2 in regulating intestinal cell differentiation.