Department of Microbiology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
J Korean Med Sci. 2009 Oct;24(5):918-29. doi: 10.3346/jkms.2009.24.5.918. Epub 2009 Sep 23.
CpG-island margins and non-island-CpG sites round the transcription start sites of CpG-island-positive and -negative genes are methylated to various degrees in a tissue-specific manner. These methylation-variable CpG sites were analyzed to delineate a relationship between the methylation and transcription of the tissue-specific genes. The level of tissue-specific transcription was estimated by counting the number of the total transcripts in the SAGE (serial analysis of gene expression) database. The methylation status of 12 CpG-island margins and 21 non-island CpG sites near the key tissue-specific genes was examined in pluripotent stromal cells obtained from fat and bone marrow samples as well as in lineage-committed cells from marrow bulk, stomach, colon, breast, and thyroid samples. Of the 33 CpG sites examined, 10 non-island-CpG sites, but none of the CpG-island margins were undermethylated concurrent with tissue-specific expression of their nearby genes. The net methylation of the 33 CpG sites and the net amount of non-island-CpG gene transcripts were high in stomach tissues and low in stromal cells. The present findings suggest that the methylation of the non-island-CpG sites is inversely associated with the expression of the nearby genes, and the concert effect of transitional-CpG methylation is linearly associated with the stomach-specific genes lacking CpG-islands.
CpG 岛边缘和非 CpG 岛启动子周围的 CpG 位点在组织特异性方式中以不同程度甲基化。这些甲基化可变 CpG 位点被分析以描绘组织特异性基因的甲基化与转录之间的关系。组织特异性转录的水平通过在 SAGE（基因表达的序列分析）数据库中计数总转录本的数量来估计。在从脂肪和骨髓样本获得的多能基质细胞以及来自骨髓、胃、结肠、乳腺和甲状腺样本的谱系定向细胞中，检查了 12 个 CpG 岛边缘和 21 个靠近关键组织特异性基因的非 CpG 岛 CpG 位点的甲基化状态。在检查的 33 个 CpG 位点中，10 个非 CpG 岛 CpG 位点，但没有 CpG 岛边缘与附近基因的组织特异性表达同时被低甲基化。33 个 CpG 位点的净甲基化和非 CpG 岛基因转录本的净量在胃组织中较高，在基质细胞中较低。本研究结果表明，非 CpG 岛 CpG 位点的甲基化与附近基因的表达呈负相关，过渡性 CpG 甲基化的协同效应与缺乏 CpG 岛的胃特异性基因呈线性相关。
