Promoter-restricted histone code, not the differentially methylated DNA regions or antisense transcripts, marks the imprinting status of IGF2R in human and mouse
Promoter-restricted histone code, not the differentially methylated DNA regions or antisense transcripts, marks the imprinting status of IGF2R in human and mouse
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DOI：
10.1093/hmg/ddh244
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发表时间：
2004-10-01
影响因子：
3.5
通讯作者：
Hoffman, AR
中科院分区：
文献类型：
--
作者：
Vu, TH;Li, T;Hoffman, AR
小鼠Igf 2 r的印记取决于内含子差异甲基化DNA区域（DMR）和Air反义转录物的存在。然而，尽管存在Air，小鼠Igf 2 r在脑中的双等位基因表达仍发生，并且尽管存在内含子DMR，人IGF 2 R在外周组织中的双等位基因表达仍发生。我们使用染色质免疫沉淀（ChIP）试验结合定量真实的时间PCR检测了小鼠和人Igf 2 R/IGF 2 R中的组蛋白修饰。启动子区组蛋白H3的Lys 4和Lys 9的甲基化分别标志着活性和沉默的等位基因。我们测量了Igf 2 r和Air启动子中的二甲基和三甲基Lys 4和Lys 9。虽然二甲基和三甲基Lys 4都标记了活性Igf 2 r和活性Air等位基因，但三甲基Lys 9而不是二甲基Lys 9标记了抑制的Air等位基因。我们在此表明，启动子区域中亲本等位基因特异性组蛋白修饰的富集，而不是DNA甲基化或反义转录的存在，正确鉴定了Igf 2 r/IGF 2 R的组织和物种特异性印迹状态。我们讨论了这些发现，在最近的进展，在确定特定组件的表观遗传标记的印记基因。
Imprinting of the mouse Igf2r depends upon an intronic differentially methylated DNA region (DMR) and the presence of the Air antisense transcript. However, biallelic expression of mouse Igf2r in brain occurs despite the presence of Air, and biallelic expression of human IGF2R in peripheral tissues occurs despite the presence of an intronic DMR. We examined histone modifications throughout the mouse and human Igf2r/IGF2R using chromatin immuno-precipitation (ChIP) assays in combination with quantitative real time PCR. Methylation of Lys4 and Lys9 of histone H3 in the promoter regions marks the active and silenced alleles, respectively. We measured di- and tri-methyl Lys4 and Lys9 across the Igf2r and Air promoters. While both di- and tri-methyl Lys4 marked the active Igf2r and the active Air allele, tri-methyl Lys9, but not di-methyl Lys9, marked the suppressed Air allele. We show here that enrichment of parental allele-specific histone modifications in the promoter region, rather than the presence of DNA methylation or antisense transcription, correctly identifies the tissue- and species- specific imprinting status of Igf2r/IGF2R. We discuss these findings in light of recent progress in identifying specific components of the epigenetic marks in imprinted genes.