An upstream polymorphism associated with lactase persistence has increased enhancer activity
An upstream polymorphism associated with lactase persistence has increased enhancer activity
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DOI：
10.1053/j.gastro.2003.09.031
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发表时间：
2003-12-01
期刊：
影响因子：
29.4
通讯作者：
Sjöström, H
中科院分区：
文献类型：
--
作者：
Troelsen, JT;Olsen, J;Sjöström, H
背景与目的：一些人在童年时期肠道乳糖酶活性下降。最近的一项研究表明，这种乳糖酶持续或不持续的表型多态与-13910位的T/C核苷酸多态和-22018位的A/G核苷酸多态有大约97%的关联。本研究的目的是探讨这些核苷酸多态性对乳糖酶-根茎苷水解酶(LPH)基因表达的影响。方法：从乳糖酶持续型和非持续型个体中分别克隆-13910和-22018区域，并用肠道细胞系Caco-2进行基因转录调控实验。凝胶迁移率改变分析(EMSA)被用来研究蛋白质/DNA与-13910序列的相互作用。结果：我们发现-13910区域含有一个很强的增强子。乳糖酶持久(-13910T变种)和非持久乳糖酶(-13910C变种)的-13910区域都具有增强活性。然而，在分化的Caco-2细胞中分析时，-13910T变体对LPH启动子的增强作用大约是-13910C变体的4倍。来自肠道和非肠道提取物的核因子与-13910T变异体结合很强，而与-13910C变异体的结合要弱得多。结论：发现-13910位点2个等位基因的功能差异，支持乳糖酶持续性和非持续性之间的分子差异是由-13910位点突变引起的。
Background & Aims: Intestinal lactase activity declines during childhood in some humans. This phenotypic polymorphism of lactase persistence or nonpersistence into adult life has been shown in a recent study to be 100% associated with a T/C nucleotide polymorphism at position -13910 and approximately 97% with an A/G nucleotide polymorphism at position -22018. The aim of this study was to investigate the role of these nucleotide polymorphisms for lactase-phlorizin hydrolase (LPH) gene expression. Methods: The -13910 and -22018 regions were cloned from lactase-persistent and -non-persistent individuals, and the regions were analyzed for gene regulatory activity of a luciferase reporter gene by transfection experiments using the intestinal cell line Caco-2. Electrophoretic mobility shift assays (EMSAs) were used to investigate protein/DNA interactions with the -13910 sequence. Results: We show that the -13910 region contains a strong enhancer. The -13910 regions from both lactase persistent (-13910T variant) and lactase nonpersistent (-13910C variant) have enhancer activity. However, the -13910T variant enhances the LPH promoter approximately 4 times more than the -13910C variant when analyzed in differentiated Caco-2 cells. A nuclear factor from both an intestinal and a non-intestinal extract binds strongly to the -13910T variant whereas the binding to the -13910C variant is much weaker. Conclusions: The discovery of a functional difference between the 2 alleles at position -13910 supports the notion that the molecular difference between lactase persistence and nonpersistence is caused by the mutation at position -13910.