Maintenance of self-renewal ability of mouse embryonic stem cells in the absence of DNA methyltransferases Dnmt1, Dnmt3a and Dnmt3b
Maintenance of self-renewal ability of mouse embryonic stem cells in the absence of DNA methyltransferases Dnmt1, Dnmt3a and Dnmt3b
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DOI：
10.1111/j.1365-2443.2006.00984.x
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发表时间：
2006-07-01
期刊：
影响因子：
2.1
通讯作者：
Okano, Masaki
中科院分区：
文献类型：
--
作者：
Tsumura, Akiko;Hayakawa, Tomohiro;Okano, Masaki
DNA甲基转移酶Dnmt 1、Dnmt 3a和Dnmt 3b协同调节哺乳动物基因组中CpG二核苷酸的胞嘧啶甲基化，为基因沉默和维持基因组完整性提供了表观遗传学基础。适当的CpG甲基化是各种体细胞类型正常生长所必需的，表明其在哺乳动物细胞的基本细胞功能中的重要作用。然而，先前使用Dnmt 1（-/-）或Dnmt 3a（-/-）Dnmt 3b（-/-）ES细胞的研究表明，未分化的胚胎干（ES）细胞可以耐受低甲基化以促进其增殖。为了研究CpG DNA甲基转移酶功能完全丧失的影响，我们通过基因打靶建立了缺乏所有这三种酶的小鼠ES细胞。尽管没有CpG甲基化，如全基因组甲基化分析所示，这些三重敲除（TKO）ES细胞生长健壮，并保持其未分化的特征。TKO ES细胞保留了在组蛋白H3和异染色质蛋白-1的Lys 9处标记有甲基化的着丝粒周围异染色质结构域，并保持其正常的染色体数目。我们的研究结果表明，ES细胞可以保持干细胞的特性和染色体的稳定性，在没有CpG甲基化和CpG DNA甲基转移酶。
DNA methyltransferases Dnmt1, Dnmt3a and Dnmt3b cooperatively regulate cytosine methylation in CpG dinucleotides in mammalian genomes, providing an epigenetic basis for gene silencing and maintenance of genome integrity. Proper CpG methylation is required for the normal growth of various somatic cell types, indicating its essential role in the basic cellular function of mammalian cells. Previous studies using Dnmt1(-/-) or Dnmt3a(-/-)Dnmt3b(-/-) ES cells, however, have shown that undifferentiated embryonic stem (ES) cells can tolerate hypomethylation for their proliferation. In an attempt to investigate the effects of the complete loss of CpG DNA methyltransferase function, we established mouse ES cells lacking all three of these enzymes by gene targeting. Despite the absence of CpG methylation, as demonstrated by genome-wide methylation analysis, these triple knockout (TKO) ES cells grew robustly and maintained their undifferentiated characteristics. TKO ES cells retained pericentromeric heterochromatin domains marked with methylation at Lys9 of histone H3 and heterochromatin protein-1, and maintained their normal chromosome numbers. Our results indicate that ES cells can maintain stem cell properties and chromosomal stability in the absence of CpG methylation and CpG DNA methyltransferases.