Severe global DNA hypomethylation blocks differentiation and induces histone hyperacetylation in embryonic stem cells
Severe global DNA hypomethylation blocks differentiation and induces histone hyperacetylation in embryonic stem cells
复制标题
DOI：
10.1128/mcb.24.20.8862-8871.2004
复制
发表时间：
2004-10-01
影响因子：
5.3
通讯作者：
Ramsahoye, B
中科院分区：
文献类型：
--
作者：
Jackson, M;Krassowska, A;Ramsahoye, B
据报道，DNA甲基转移酶1缺陷（Dnmt 1（-/-））胚胎干（ES）细胞是低甲基化（20% CpG甲基化），并通过细胞凋亡诱导分化时死亡。在这里，我们表明，只有0.6%的CpG二核苷酸的Dnmt[3a（-/-），3b（-/-）] ES细胞表现不同：培养物中的大多数细胞部分或完全阻断其启动分化的能力，保持活力，同时保留碱性磷酸酶和Oct 4表达的干细胞特征。DNA甲基化水平的恢复挽救了这些缺陷。严重低甲基化的Dnmt[3a（-/-），3b（-/-）] ES细胞具有增加的组蛋白乙酰化水平，并且那些可以分化的细胞异常表达分化的胚外标记物。具有> 10%CpG甲基化的Dnmt[3a（-/-），3b（-/-）] ES细胞能够终末分化，而具有20%CpG甲基化的Dnmt 1（-/-）ES细胞不能分化。这表明成功的终末分化不仅仅依赖于足够的甲基化水平。存在由维持酶Dnmt 1递送甲基化的绝对要求。
It has been reported that DNA methyltransferase 1-deficient (Dnmt1(-/-)) embryonic stem (ES) cells are hypomethylated (20% CpG methylation) and die through apoptosis when induced to differentiate. Here, we show that Dnmt[3a(-/-),3b(-/-)] ES cells with just 0.6% of their CpG dinucleotides behave differently: the majority of cells within the culture are partially or completely blocked in their ability to initiate differentiation, remaining viable while retaining the stem cell characteristics of alkaline phosphatase and Oct4 expression. Restoration of DNA methylation levels rescues these defects. Severely hypomethylated Dnmt[3a(-/-),3b(-/-)] ES cells have increased histone acetylation levels, and those cells that can differentiate aberrantly express extraembryonic markers of differentiation. Dnmt[3a(-/-),3b(-/-)] ES cells with >10% CpG methylation are able to terminally differentiate, whereas Dnmt1(-/-) ES cells with 20% of the CpG methylated cannot differentiate. This demonstrates that successful terminal differentiation is not dependent simply on adequate methylation levels. There is an absolute requirement that the methylation be delivered by the maintenance enzyme Dnmt1.