Asymmetric DNA methylation of CpG dyads is a feature of secondary DMRs associated with the Dlk1/Gtl2 imprinting cluster in mouse.
Asymmetric DNA methylation of CpG dyads is a feature of secondary DMRs associated with the Dlk1/Gtl2 imprinting cluster in mouse.
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DOI：
10.1186/s13072-017-0138-0
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发表时间：
2017
影响因子：
3.9
通讯作者：
Davis TL
中科院分区：
文献类型：
--
作者：
Guntrum M;Vlasova E;Davis TL
差异DNA甲基化在印记基因的调控中起着至关重要的作用。印记控制区的差异甲基化状态通过受精时的配子遗传，并在整个发育过程中稳定地维持在体细胞中，影响整个印记簇的基因表达。相比之下，DNA 甲基化模式在次要差异甲基化区域更加不稳定，这些区域是在植入后发育过程中在印记位点建立的。为了研究这些甲基化程度更高的次级差异甲基化区域的性质，我们采用发夹接头亚硫酸氢盐诱变方法来检查与两条互补链上的鼠 Dlk1/Gtl2 印记簇相关的差异甲基化区域的 CpG 二联体甲基化。我们观察到 IG-DMR 上超过 90% 的甲基化 CpG 二联体发生同甲基化，IG-DMR 作为印记控制元件。相比之下，仅在次级差异甲基化区域的 67-78% 的甲基化 CpG 二联体中观察到同甲基化；其余 22-33% 的甲基化 CpG 二联体表现出半甲基化。我们认为这种高度的半甲基化可以解释与印记位点相关的次级差异甲基化区域的 DNA 甲基化模式的变异性。我们进一步表明，二级差异甲基化区域中 5-羟甲基化的存在可能会由于被动和/或主动去甲基化机制而导致半甲基化和甲基化变异。本文的在线版本 (doi:10.1186/s13072-017-0138-0) 包含补充材料，可供授权用户使用。
Differential DNA methylation plays a critical role in the regulation of imprinted genes. The differentially methylated state of the imprinting control region is inherited via the gametes at fertilization, and is stably maintained in somatic cells throughout development, influencing the expression of genes across the imprinting cluster. In contrast, DNA methylation patterns are more labile at secondary differentially methylated regions which are established at imprinted loci during post-implantation development. To investigate the nature of these more variably methylated secondary differentially methylated regions, we adopted a hairpin linker bisulfite mutagenesis approach to examine CpG dyad methylation at differentially methylated regions associated with the murine Dlk1/Gtl2 imprinting cluster on both complementary strands. We observed homomethylation at greater than 90% of the methylated CpG dyads at the IG-DMR, which serves as the imprinting control element. In contrast, homomethylation was only observed at 67–78% of the methylated CpG dyads at the secondary differentially methylated regions; the remaining 22–33% of methylated CpG dyads exhibited hemimethylation. We propose that this high degree of hemimethylation could explain the variability in DNA methylation patterns at secondary differentially methylated regions associated with imprinted loci. We further suggest that the presence of 5-hydroxymethylation at secondary differentially methylated regions may result in hemimethylation and methylation variability as a result of passive and/or active demethylation mechanisms. The online version of this article (doi:10.1186/s13072-017-0138-0) contains supplementary material, which is available to authorized users.