Establishment and maintenance of genomic methylation patterns in mouse embryonic stem cells by Dnmt3a and Dnmt3b
Establishment and maintenance of genomic methylation patterns in mouse embryonic stem cells by Dnmt3a and Dnmt3b
复制标题
DOI：
10.1128/mcb.23.16.5594-5605.2003
复制
发表时间：
2003-08-01
影响因子：
5.3
通讯作者：
Li, E
中科院分区：
文献类型：
--
作者：
Chen, TP;Ueda, Y;Li, E
我们以前已经表明，DNA甲基转移酶Dnmt 3a和Dnmt 3b进行从头，小鼠基因组的甲基化在早期着床后发育和母源性印记基因在卵母细胞。在本研究中，我们证明了Dnmt 3a和Dnmt 3b也是DNA甲基化模式的稳定遗传或“维持”所必需的。胚胎干细胞中Dnmt 3a和Dnmt 3b的失活导致各种重复序列和单拷贝基因的甲基化逐渐丧失。有趣的是，将Dnmt 3a、Dnmt 3a 2和Dnmt 3b 1同种型引入高度去甲基化的突变ES细胞中可以恢复基因组甲基化模式;这些同种型似乎具有共同和不同的DNA靶点，但它们都无法恢复母体甲基化印记。相反，Dnmt 1和Dnmt 3b 3的过表达未能恢复DNA甲基化模式，因为它们不能催化体内从头甲基化。我们还表明，Dnmt 3a和Dnmt 3b对基因组DNA的超甲基化是ES细胞在裸小鼠中形成畸胎瘤所必需的。这些结果表明，基因组甲基化模式部分地通过不同的Dnmt 3a和Dnmt 3b亚型的差异表达来确定。
We have previously shown that the DNA methyltransferases Dnmt3a and Dnmt3b carry out de novo, methylation of the mouse genome during early postimplantation development and of maternally imprinted genes in the oocyte. In the present study, we demonstrate that Dnmt3a and Dnmt3b are also essential for the stable inheritance, or "maintenance," of DNA methylation patterns. Inactivation of both Dnmt3a and Dnmt3b in embryonic stem (ES) cells results in progressive loss of methylation in various repeats and single-copy genes. Interestingly, introduction of the Dnmt3a, Dnmt3a2, and Dnmt3b1 isoforms back into highly demethylated mutant ES cells restores genomic methylation patterns; these isoforms appear to have both common and distinct DNA targets, but they all fail to restore the maternal methylation imprints. In contrast, overexpression of Dnmt1 and Dnmt3b3 failed to restore DNA methylation patterns due to their inability to catalyze de novo, methylation in vivo. We also show that hypermethylation of genomic DNA by Dnmt3a and Dnmt3b is necessary for ES cells to form teratomas in nude mice. These results indicate that genomic methylation patterns are determined partly through differential expression of different Dnmt3a and Dnmt3b isoforms.