Yun Jihye, Park Chang Won, Lee Young Jae, Chung Jae Hoon
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Taejon 305-701, South Korea.
Mamm Genome. 2003 Jun;14(6):376-82. doi: 10.1007/s00335-002-2252-x.
We previously reported that the mouse Copg2 (Coatomer Protein Subunit Gamma 2) gene was imprinted in the intraspecific F(1) hybrid mice between C57BL/6 and M. m. molossinus. In this study, methylation status at the promoter-associated CpG island and allele-specific expression pattern of Copg2 were investigated in the interspecific F(1) hybrid (C57BL/6 x M. spretus). We found that Copg2 was biallelically expressed in the interspecific F(1) hybrid, despite the presence of a differentially methylated region (DMR) in the CpG island. Therefore, paternal-specific methylation at the CpG island of Copg2 is not accompanied by allele-specific expression of Copg2 in the F(1) hybrid (C57BL/6 x M. spretus). The results suggest that the imprinted pattern of Copg2 expression is subject to variable epigenetic control systems of different mouse species. In addition, we identified a novel antisense transcript, Copg2AS2, at the Copg2 promoter region. The antisense transcript was expressed monoallelically, indicating that the differential expression of the antisense transcript is correlated with the differential methylation at the CpG island of Copg2.
我们之前报道过，小鼠Copg2（包被蛋白亚基γ2）基因在C57BL/6和小家鼠亚种间的种内F(1)杂交小鼠中是印记基因。在本研究中，我们对种间F(1)杂交小鼠（C57BL/6×西班牙小鼠）中Copg2启动子相关CpG岛的甲基化状态和等位基因特异性表达模式进行了研究。我们发现，尽管CpG岛存在差异甲基化区域（DMR），Copg2在种间F(1)杂交小鼠中是双等位基因表达。因此，Copg2的CpG岛的父本特异性甲基化并不伴随Copg2在F(1)杂交小鼠（C57BL/6×西班牙小鼠）中的等位基因特异性表达。这些结果表明，Copg2表达的印记模式受不同小鼠物种可变的表观遗传控制系统调控。此外，我们在Copg2启动子区域鉴定出一个新的反义转录本Copg2AS2。该反义转录本是单等位基因表达，这表明反义转录本的差异表达与Copg2的CpG岛的差异甲基化相关。
