A Randomly Integrated Transgenic H19 Imprinting Control Region Acquires Methylation Imprinting Independently of Its Establishment in Germ Cells
A Randomly Integrated Transgenic H19 Imprinting Control Region Acquires Methylation Imprinting Independently of Its Establishment in Germ Cells
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DOI：
10.1128/mcb.00275-09
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发表时间：
2009-09-01
影响因子：
5.3
通讯作者：
Tanimoto, Keiji
中科院分区：
文献类型：
--
作者：
Matsuzaki, Hitomi;Okamura, Eiichi;Tanimoto, Keiji
小鼠Igf 2/H19基因座的印迹表达受印迹控制区（ICR）的差异甲基化控制，ICR最初在生殖细胞中建立，随后在体细胞中维持，这取决于其亲本来源。通过将2.9 kbp的H19 ICR片段移植到转基因小鼠的人β-珠蛋白酵母人工染色体中，我们先前表明ICR可以重现异源基因座上的印迹甲基化和表达，这表明β-珠蛋白基因座上的H19 ICR包含足够的信息来维持甲基化标记（K. Tanimoto，M. Shimotsuma，H. Matsuzaki，A.作者声明：J.恩格尔和A. Jiamizu，Proc. Natl. Acad. Sci. USA 102：10250-10255，2005）。然而，奇怪的是，转基因H19 ICR在精子中没有甲基化，这与在内源基因座中观察到的不同。在这里，我们使用更严格的标准重新评估了H19 ICR标记亲本来源的能力。在睾丸中，单独的2.9 kbp的转基因ICR片段的甲基化水平在6个转基因小鼠品系之间差异显着。然而，在体细胞中，父系遗传的ICR片段在小鼠基因组中六个随机整合位点中的五个位点上表现出一贯较高的甲基化水平。这些结果清楚地表明，H19 ICR可以在受精后获得亲本来源依赖性甲基化，而不依赖于染色体整合位点或雄性生殖细胞中的先决条件甲基化获得。
The imprinted expression of the mouse Igf2/H19 locus is governed by the differential methylation of the imprinting control region (ICR), which is established initially in germ cells and subsequently maintained in somatic cells, depending on its parental origin. By grafting a 2.9-kbp H19 ICR fragment into a human beta-globin yeast artificial chromosome in transgenic mice, we previously showed that the ICR could recapitulate imprinted methylation and expression at a heterologous locus, suggesting that the H19 ICR in the beta-globin locus contained sufficient information to maintain the methylation mark (K. Tanimoto, M. Shimotsuma, H. Matsuzaki, A. Omori, J. Bungert, J. D. Engel, and A. Fukamizu, Proc. Natl. Acad. Sci. USA 102:10250-10255, 2005). Curiously, however, the transgenic H19 ICR was not methylated in sperm, which was distinct from that seen in the endogenous locus. Here, we reevaluated the ability of the H19 ICR to mark the parental origin using more rigid criteria. In the testis, the methylation levels of the solitary 2.9-kbp transgenic ICR fragment varied significantly between six transgenic mouse lines. However, in somatic cells, the paternally inherited ICR fragment exhibited consistently higher methylation levels at five out of six randomly integrated sites in the mouse genome. These results clearly demonstrated that the H19 ICR could acquire parent-of-origin-dependent methylation after fertilization independently of the chromosomal integration site or the prerequisite methylation acquisition in male germ cells.