title: CpG methylation profiles of endothelial cell-specific gene promoter regions in adipose tissue stem cells suggest limited differentiation potential toward the endothelial cell lineage.
abstract: In vivo endothelial commitment of adipose stem cells (ASCs) has scarcely been reported, and controversy remains on the contribution of ASCs to vascularization. We address the epigenetic commitment of ASCs to the endothelial lineage. We report a bisulfite sequencing analysis of CpG methylation in the promoters of two endothelial-cell-specific genes, CD31 and CD144, in freshly isolated and in cultures of ASCs before and after induction of endothelial differentiation. In contrast to adipose tissue-derived endothelial (CD31(+)) cells, freshly isolated ASCs display a heavily methylated CD31 promoter and a mosaically methylated CD144 promoter despite basal transcription of both genes. Methylation state of both promoters remains globally stable upon culture. Endothelial stimulation of ASCs in methylcellulose elicits phenotypic changes, marginal upregulation of CD31, and CD144 expression and restrictive induction of a CD31(+)CD144(+) immunophenotype. These events are accompanied by discrete changes in CpG methylation in CD31 and CD144 promoters; however, no global demethylation that marks CD31(+) cells and human umbilical vein endothelial cells occurs. Immunoselection of CD31(+) cells after endothelial stimulation reveals consistent demethylation of one CpG immediately 3' of the transcription start site of the CD31 promoter. Adipogenic or osteogenic differentiation maintains CD31 and CD144 methylation patterns of undifferentiated cells. Methylation profiles of CD31 and CD144 promoters suggest a limited commitment of ASCs to the endothelial lineage. This contrasts with the reported hypomethylation of adipogenic promoters, which reflects a propensity of ASCs toward adipogenic differentiation. Analysis of CpG methylation at lineage-specific promoters provides a robust assessment of epigenetic commitment of stem cells to a specific lineage.
authors.affiliation: Institute of Basic Medical Sciences, Faculty of Medicine, Department of Biochemistry, University of Oslo, Oslo, Norway.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Boquest
authors.forename: Agate
authors.initials: A
authors.lastname: Noer
authors.forename: Anita L
authors.initials: AL
authors.lastname: Sørensen
authors.forename: Kristin
authors.initials: K
authors.lastname: Vekterud
authors.forename: Philippe
authors.initials: P
authors.lastname: Collas
mesh_terms: D000273:Adipose Tissue / Q000166:cytology* / Q000502:physiology; D015703:Antigens, CD; D002454:Cell Differentiation / Q000502:physiology*; D015226:Dinucleoside Phosphates / Q000235:genetics*; D004730:Endothelium, Vascular / Q000166:cytology*; D006801:Humans; D016130:Immunophenotyping; D008745:Methylation; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D011401:Promoter Regions, Genetic; D013234:Stem Cells / Q000166:cytology* / Q000502:physiology*; D014471:Umbilical Veins
chemical_list: D015703:Antigens, CD; D015226:Dinucleoside Phosphates; D019408:Platelet Endothelial Cell Adhesion Molecule-1; C015772:CpG dinucleotide