Antagonism between DNA hypermethylation and enhancer-blocking activity at the H19 DMD is uncovered by CpG mutations
Antagonism between DNA hypermethylation and enhancer-blocking activity at the H19 DMD is uncovered by CpG mutations
复制标题
DOI：
10.1038/ng1399
复制
发表时间：
2004-08-01
期刊：
影响因子：
30.8
通讯作者：
Bartolomei, MS
中科院分区：
文献类型：
--
作者：
Engel, N;West, AG;Bartolomei, MS
H19-Igf 2位点的印记表达依赖于差异甲基化结构域（DMD），该结构域既作为母体特异性甲基化敏感绝缘子，又作为父系特异性超甲基化位点。DMD中的四个重复序列结合母亲等位基因上的CCCTC结合因子（CTCF），并且已经提出吸引父亲等位基因上的甲基化。我们将点突变引入DMD以耗尽CpG的重复序列，同时保留CTCF结合和增强子阻断活性。突变的母系遗传使H19表达和Igf 2印迹保持完整，这与DMD作为绝缘体的想法一致。相反，这些突变的父系遗传破坏了DMD甲基化的维持，导致双等位基因H19表达。此外，在体内父系遗传突变等位基因上建立了绝缘子，降低了Igf 2的表达，导致新生后代的大小减少了40%。因此，DMD中的9个CpG突变表明H19 DMD的两个亲本特异性作用，甲基化维持和绝缘子组装，是拮抗的。
Imprinted expression at the H19-Igf2 locus depends on a differentially methylated domain (DMD) that acts both as a maternal-specific, methylation-sensitive insulator and as a paternal-specific site of hypermethylation. Four repeats in the DMD bind CCCTC-binding factor ( CTCF) on the maternal allele and have been proposed to attract methylation on the paternal allele. We introduced point mutations into the DMD to deplete the repeats of CpGs while retaining CTCF-binding and enhancer-blocking activity. Maternal inheritance of the mutations left H19 expression and Igf2 imprinting intact, consistent with the idea that the DMD acts as an insulator. Conversely, paternal inheritance of these mutations disrupted maintenance of DMD methylation, resulting in biallelic H19 expression. Furthermore, an insulator was established on the paternally inherited mutated allele in vivo, reducing Igf2 expression and resulting in a 40% reduction in size of newborn offspring. Thus, the nine CpG mutations in the DMD showed that the two parental-specific roles of the H19 DMD, methylation maintenance and insulator assembly, are antagonistic.