Genomic imprinting recapitulated in the human beta-globin locus.
Genomic imprinting recapitulated in the human beta-globin locus.
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人类β-珠蛋白基因座中基因组印记的重现。
DOI：
10.1073/pnas.0409541102
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发表时间：
2005
影响因子：
11.1
通讯作者：
Fukamizu,Akiyoshi
中科院分区：
文献类型：
--
作者：
Tanimoto,Keiji;Shimotsuma,Motoshi;Matsuzaki,Hitomi;Omori,Akane;Bungert,Jörg;Engel,JamesDouglas;Fukamizu,Akiyoshi
哺乳动物中的一个基因子集受到基因组印记的影响。例如，小鼠H19基因只有在母系遗传时才有活性，而相邻的Igf 2基因则在父系表达。这种印迹表达模式受H19基因上游的印迹控制区（ICR）调控。母系遗传的H19 ICR由于其绝缘子功能而通过下游增强子激活sIgf 2基因，而父系遗传的H19 ICR通过启动子DNA甲基化抑制H19基因转录。这些起源亲本特异性功能依赖于ICR DNA的等位基因特异性甲基化，这是在配子发生期间建立的。因此，ICR也可以作为表观遗传修饰的标志。为了研究ICR是否能自主地赋予这些活性，我们将一个2.9 kbp的含ICR的DNA片段导入人β-珠蛋白酵母人工染色体的基因座控制区的3′端，并建立了转基因小鼠系。当转基因为父系遗传时，所有β-样珠蛋白基因的表达均较高。与这一结果雅阁的是，来自有核红细胞的转基因ICR DNA在父系传递时甲基化程度更高。染色质免疫沉淀试验证实CCCTC结合因子在体内优先被募集到母体转基因ICR中。然而，令人惊讶的是，在睾丸中的生殖细胞DNA中没有观察到起源父母特异性甲基化模式，这表明甲基化是在受精后建立的。因此，ICR在正常非印迹的转基因β-珠蛋白基因位点内自主重现印迹，但印迹甲基化的时间建立不同于内源性Igf 2/H19位点。
A subset of genes in mammals are subject to genomic imprinting. The mouseH19gene, for example, is active only when maternally inherited and the neighboringIgf2gene is paternally expressed. This imprinted expression pattern is regulated by the imprinting control region (ICR) upstream of theH19gene. A maternally inheritedH19ICR inhibitsIgf2gene activation by the downstream enhancer due to its insulator function while it suppressesH19gene transcription by promoter DNA methylation when paternally inherited. These parent-of-origin specific functions depend on the allele-specific methylation of the ICR DNA, which is established during gametogenesis. Therefore, the ICR may also function as a landmark for epigenetic modifications. To examine whether the ICR confers these activities autonomously, we introduced a 2.9-kbp ICR-containing DNA fragment into a human β-globin yeast artificial chromosome at the 3′ end of the locus control region and established transgenic mouse lines. Expression of all of the β-like globin genes was higher when the transgene was paternally inherited. In accord with this result, transgenic ICR DNA from nucleated erythrocytes was more heavily methylated when paternally transmitted. Chromatin immunoprecipitation assays confirmed that CCCTC binding factor is preferentially recruited to the maternal transgenic ICRin vivo. Surprisingly however, the parent-of-origin specific methylation pattern was not observed in germ cell DNA in testis, demonstrating that methylation was established after fertilization. Thus, the ICR autonomously recapitulated imprinting within the normally nonimprinted transgenic β-globin gene locus, but the temporal establishment of imprinting methylation differs from that at the endogenousIgf2/H19locus.