title: Stable CpG hypomethylation of adipogenic promoters in freshly isolated, cultured, and differentiated mesenchymal stem cells from adipose tissue.
abstract: Mesenchymal stem cells from adipose tissue can differentiate into mesodermal lineages. Differentiation potential, however, varies between clones of adipose stem cells (ASCs), raising the hypothesis that epigenetic differences account for this variability. We report here a bisulfite sequencing analysis of CpG methylation of adipogenic (leptin [LEP], peroxisome proliferator-activated receptor gamma 2 [PPARG2], fatty acid-binding protein 4 [FABP4], and lipoprotein lipase [LPL]) promoters and of nonadipogenic (myogenin [MYOG], CD31, and GAPDH) loci in freshly isolated human ASCs and in cultured ASCs, in relation to gene expression and differentiation potential. Uncultured ASCs display hypomethylated adipogenic promoters, in contrast to myogenic and endothelial loci, which are methylated. Adipogenic promoters exhibit mosaic CpG methylation, on the basis of heterogeneous methylation between cells and of variation in the extent of methylation of a given CpG between donors, and both between and within clonal cell lines. DNA methylation reflects neither transcriptional status nor potential for gene expression upon differentiation. ASC culture preserves hypomethylation of adipogenic promoters; however, between- and within-clone mosaic methylation is detected. Adipogenic differentiation also maintains the overall CpG hypomethylation of LEP, PPARG2, FABP4, and LPL despite demethylation of specific CpGs and transcriptional induction. Furthermore, enhanced methylation at adipogenic loci in primary differentiated cells unrelated to adipogenesis argues for ASC specificity of the hypomethylated state of these loci. Therefore, mosaic hypomethylation of adipogenic promoters may constitute a molecular signature of ASCs, and DNA methylation does not seem to be a determinant of differentiation potential of these cells.
authors.affiliation: Department of Biochemistry, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway.
authors.forename: Agate
authors.initials: A
authors.lastname: Noer
authors.forename: Anita L
authors.initials: AL
authors.lastname: Sørensen
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Boquest
authors.forename: Philippe
authors.initials: P
authors.lastname: Collas
mesh_terms: D050156:Adipogenesis / Q000235:genetics*; D000273:Adipose Tissue / Q000166:cytology*; D019070:Cell Lineage; D002469:Cell Separation; D002478:Cells, Cultured; D002999:Clone Cells; D018899:CpG Islands / Q000235:genetics*; D019175:DNA Methylation; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D020738:Leptin / Q000235:genetics; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D020738:Leptin; D012333:RNA, Messenger