• Seung-Jin Hong, Moo-Il Kang, Jung-Hwan Oh, Yu-Chae Jung, Young-Ho Kim, Sung-Ja Kim, Seung-Hye Choi, Eun-Joo Seo, Sang-Wook Choi, and Mun-Gan Rhyu.
• Department of Microbiology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
• J. Korean Med. Sci. 2009 Oct 1; 24 (5): 918-29.

AbstractCpG-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.

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