An epigenetic regulatory element of the Nodal gene in the mouse and human genomes
An epigenetic regulatory element of the Nodal gene in the mouse and human genomes
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DOI：
10.1016/j.mod.2014.12.003
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发表时间：
2015-05-01
影响因子：
2.6
通讯作者：
Shiota, Kunio
中科院分区：
文献类型：
--
作者：
Arai, Daisuke;Hayakawa, Koji;Shiota, Kunio
节点信号在胚胎发育过程中起着关键作用。淋巴结基因在成人组织中不表达，但在癌细胞中经常被激活，促进恶性肿瘤的进展。虽然已经确定了Nodal基因的几个调控元件，但长期调控Nodal表达的表观遗传机制仍不清楚。我们发现，在转录起始位点（TSS）上游约-3.0 kb至-0.4 kb的区域，DNA甲基化表现出动态变化，我们将其称为表观遗传调控元件（ERE）。ERE在小鼠胚胎干细胞（mESCs）中未甲基化，但在分化的细胞和组织中甲基化程度越来越高，同时伴有Nodal mRNA表达的下调。体外报告基因分析在ERE中发现了一个Oct3/4结合基序，表明ERE负责mESCs中Nodal的激活。此外，ERE是分化相关Polycomb沉默的靶标，当mESCs分化为胚状体（EBs）时，染色质浓缩。药物抑制PRC2可导致EBs和小鼠胚胎成纤维细胞（mef）中Nodal表达的再激活。在正常人类细胞中，ERE也被PRC2靶向。在表达nodal的人癌细胞中，EZH2的积累和ERE处H3K27的三甲基化减少。综上所述，Nodal在小鼠胚胎和人类细胞中通过ERE受到表观遗传控制。2014爱思唯尔爱尔兰有限公司版权所有。
Nodal signaling plays critical roles during embryonic development. The Nodal gene is not expressed in adult tissues but is frequently activated in cancer cells, contributing to progression toward malignancy. Although several regulatory elements of the Nodal gene have been identified, the epigenetic mechanisms by which Nodal expression is regulated over the long term remain unclear. We found a region exhibiting dynamic changes in DNA methylation at approximately -3.0 kb to -0.4 kb upstream from the transcriptional start site (TSS) that we termed the epigenetic regulatory element (ERE). The ERE was unmethylated in mouse embryonic stem cells (mESCs) but became increasingly methylated in differentiated cells and tissues, concomitant with the downregulation of Nodal mRNA expression. In vitro reporter assays identified an Oct3/4 binding motif within the ERE, indicating that the ERE is responsible for the activation of Nodal in mESCs. Furthermore, the ERE was a target of differentiation-associated Polycomb silencing, and the chromatin condensed when mESCs differentiated to embryoid bodies (EBs). Pharmacological inhibition of PRC2 led to the reactivation of Nodal expression in EBs and mouse embryonic fibroblasts (MEFs). The ERE was also targeted by PRC2 in normal human cells. In NODAL-expressing human cancer cells, accumulation of EZH2 and trimethylation of H3K27 at the ERE were diminished. In conclusion, Nodal is epigenetically controlled through the ERE in the mouse embryo and human cells. (C) 2014 Elsevier Ireland Ltd. All rights reserved.