DNA demethylation reactivates a subset of imprinted genes in uniparental mouse embryonic fibroblasts
DNA demethylation reactivates a subset of imprinted genes in uniparental mouse embryonic fibroblasts
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DOI：
10.1074/jbc.m009392200
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发表时间：
2001-03-23
影响因子：
4.8
通讯作者：
Stewart, CL
中科院分区：
文献类型：
--
作者：
El Kharroubi, A;Piras, G;Stewart, CL
虽然大多数印迹基因在DNA甲基化方面表现出等位基因差异，但尚不清楚甲基化是否调控体细胞中部分或全部印迹基因的表达。为了研究印迹等位基因沉默的机制，我们产生了新的单亲小鼠胚胎成纤维细胞，只含有父亲或母亲的基因组。这些成纤维细胞保留了12个印迹基因的亲本等位基因特异性表达，检测了超过30代细胞。我们发现，p57（Kip 2）（细胞周期蛋白依赖性激酶抑制剂蛋白2）和Igf 2（胰岛素样生长因子2）通过抑制组蛋白脱乙酰酶诱导;然而，它们的激活状态通过停用阿司他丁A迅速逆转。相反，DNA去甲基化导致印迹基因子集的遗传表达，包括H19（H19胎肝mRNA），p57（Kip 2），Peg 3/Pw 1（父系表达基因3）和Zac 1（调节细胞凋亡和细胞周期停滞的锌指结合蛋白）。其他印记基因如Grb 10（生长因子受体结合蛋白10）、Peg 1/Mest（父系表达基因1/中胚层特异性转录物）、Sgce（ε-肌聚糖）、Snrpn（小核核糖核蛋白多肽N）和U2 af 1（U2小核核糖核蛋白辅助因子），尽管暴露于组蛋白去乙酰化酶和DNA甲基化的抑制剂，仍保持不活动。这些结果表明，DNA甲基化而不是组蛋白乙酰化的变化在体细胞中的一些印记位点产生了可遗传的表观遗传状态。
Although most imprinted genes show allelic differences in DNA methylation, it is not clear whether methylation regulates the expression of some or all imprinted genes in somatic cells. To examine the mechanisms of silencing of imprinted alleles, we generated novel uniparental mouse embryonic fibroblasts exclusively containing either the paternal or the maternal genome. These fibroblasts retain parent-of-origin allele-specific expression of 12 imprinted genes,examined for more than 30 cell generations. We show that p57(Kip2) (cyclin-dependent kinase inhibitor protein 2) and Igf2 (insulinlike growth factor 2) are induced by inhibiting histone deacetylases; however, their activated state is reversed quickly by withdrawal of trichostatin A. In contrast, DNA demethylation results in the heritable expression of a subset of imprinted genes including H19 (H19 fetal liver mRNA), p57(Kip2), Peg3/Pw1 (paternally expressed gene 3), and Zac1 (zinc finger-binding protein regulating apoptosis and cell cycle arrest). Other imprinted genes such as Grb10 (growth factor receptor-bound protein 10), Peg1/Mest (paternally expressed gene 1/mesoderm-specific transcript), Sgce (epsilon-sarcoglycan), Snrpn (small nuclear ribonucleoprotein polypeptide N), and U2af1 (U2 small nuclear ribonucleoprotein auxiliary factor), remain inactive, despite their exposure to inhibitors of histone deacetylases and DNA methylation. These results demonstrate that changes in DNA methylation but not histone acetylation create a heritable epigenetic state at some imprinted loci in somatic cells.