Department of Nutrition, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
J Biol Chem. 2011 Jan 14;286(2):1649-58. doi: 10.1074/jbc.M110.106922. Epub 2010 Nov 8.
When dietary choline is restricted, most men and postmenopausal women develop multiorgan dysfunction marked by hepatic steatosis (choline deficiency syndrome (CDS)). However, a significant subset of premenopausal women is protected from CDS. Because hepatic PEMT (phosphatidylethanolamine N-methyltransferase) catalyzes de novo biosynthesis of choline and this gene is under estrogenic control, we hypothesized that there are SNPs in PEMT that disrupt the hormonal regulation of PEMT and thereby put women at risk for CDS. In this study, we performed transcript-specific gene expression analysis, which revealed that estrogen regulates PEMT in an isoform-specific fashion. Locus-wide SNP analysis identified a risk-associated haplotype that was selectively associated with loss of hormonal activation. Chromatin immunoprecipitation, analyzed by locus-wide microarray studies, comprehensively identified regions of estrogen receptor binding in PEMT. The polymorphism (rs12325817) most highly linked with the development of CDS (p < 0.00006) was located within 1 kb of the critical estrogen response element. The risk allele failed to bind either the estrogen receptor or the pioneer factor FOXA1. These data demonstrate that allele-specific ablation of estrogen receptor-DNA interaction in the PEMT locus prevents hormone-inducible PEMT expression, conferring risk of CDS in women.
当饮食中的胆碱受到限制时,大多数男性和绝经后妇女都会出现多器官功能障碍,表现为肝脂肪变性(胆碱缺乏综合征(CDS))。然而,相当一部分绝经前妇女能够免受 CDS 的影响。由于肝 PEMT(磷酸乙醇胺 N-甲基转移酶)催化胆碱的从头生物合成,并且该基因受雌激素控制,我们假设 PEMT 中存在 SNP,破坏了 PEMT 的激素调节,从而使女性面临 CDS 的风险。在这项研究中,我们进行了转录特异性基因表达分析,结果表明雌激素以同工型特异性的方式调节 PEMT。全基因座 SNP 分析确定了一种与激素激活丧失相关的风险相关单倍型。通过全基因座微阵列研究进行的染色质免疫沉淀分析,全面鉴定了 PEMT 中雌激素受体结合的区域。与 CDS 发展最相关的多态性(rs12325817)(p < 0.00006)位于关键雌激素反应元件的 1 kb 内。风险等位基因未能结合雌激素受体或先驱因子 FOXA1。这些数据表明,PEMT 基因座中雌激素受体-DNA 相互作用的等位基因特异性缺失可防止激素诱导的 PEMT 表达,从而使女性面临 CDS 的风险。