title: Transitional CpG methylation between promoters and retroelements of tissue-specific genes during human mesenchymal cell differentiation.
abstract: In general, methylation of the promoter regions is inversely correlated with gene expression. The transitional CpG area between the promoter-associated CpG islands and the nearby retroelements is often methylated in a tissue-specific manner. This study analyzed the relationship between gene expression and the methylation of the transitional CpGs in two human stromal cells derived from the bone marrow (BMSC) and adipose tissue (ATSC), both of which have a multilineage differentiation potential. The transitional CpGs of the osteoblast-specific (RUNX2 and BGLAP), adipocyte-specific (PPARgamma2), housekeeping (CDKN2A and MLH1), and mesenchyme-unrelated (RUNX3) genes were examined by methylation-specific PCR. The expression of each gene was measured using reverse-transcription PCR analysis. The RUNX2, BGLAP, and CDKN2A genes in the BMSC, and the PPARgamma2 gene in the ATSC exhibited hypomethylation of the transitional CpGs along with the strong expression. The CpG island of RUNX3 gene not expressed in both BMSC and ATSC was hypermethylated. Transitional hypomethylation of the MLH1 gene was accompanied by the higher expression in the BMSC than in the ATSC. The weakly methylated CpGs of the PPARgamma2 gene in the BMSC became hypomethylated along with the strong expression during the osteoblastic differentiation. There were no notable changes in the transitional methylation and expression of the genes other than PPARgamma2 after the differentiation. Therefore, the transitional methylation and gene expression established in mesenchymal cells tend to be consistently preserved under the induction of differentiation. Weak transitional methylation of the PPARgamma2 gene in the BMSC suggests a methylation-dependent mechanism underlying the adiopogenesis of bone marrow.
authors.affiliation: Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Moo-Il
authors.initials: MI
authors.lastname: Kang
authors.forename: Hye-Soo
authors.initials: HS
authors.lastname: Kim
authors.forename: Yu-Chae
authors.initials: YC
authors.lastname: Jung
authors.forename: Young-Ho
authors.initials: YH
authors.lastname: Kim
authors.forename: Seung-Jin
authors.initials: SJ
authors.lastname: Hong
authors.forename: Mi-Kyoung
authors.initials: MK
authors.lastname: Kim
authors.forename: Ki-Hyun
authors.initials: KH
authors.lastname: Baek
authors.forename: Chun-Choo
authors.initials: CC
authors.lastname: Kim
authors.forename: Mun-Gan
authors.initials: MG
authors.lastname: Rhyu
mesh_terms: D000273:Adipose Tissue / Q000166:cytology; D001854:Bone Marrow Cells / Q000166:cytology; D002454:Cell Differentiation / Q000235:genetics*; D002478:Cells, Cultured; D018899:CpG Islands; D019175:DNA Methylation; D005786:Gene Expression Regulation; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D010006:Osteoblasts / Q000378:metabolism; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D018626:Retroelements; D017154:Stromal Cells / Q000166:cytology; D024363:Transcription Initiation Site
chemical_list: D012333:RNA, Messenger; D018626:Retroelements