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.

Methylation status of CpG islands in the promoter regions of signature genes during chondrogenesis of human synovium–derived mesenchymal stem cells

“…However, in our study, the methylation status of promoter CpG islands was found to be preserved in critical genes, such as SOX9 and RUNX2, during chondrogenesis. This observation may indicate a retained capability of the mesenchymal progenitor cells to change their differentiation status even after chondrogenesis, since similar observations about adipogenesis of MSCs have been reported (36)(37)(38)(39).…”

Epigenetic regulation of specific transcription factors in osteogenicdifferentiation of mesenchymal stem cells

“…Their results demonstrated an accumulative methyl-cytosin at the endogenous Trip 10 promoter, Trip 10 downregulation, and progressive MSC to neuron and osteocyte differentiation (Hsiao et al, 2010). In contrast to that study, lack of a remarkable alteration in DNA methylation of the promoter during in vitro differentiation of MSCs into osteocytes was reported by Kang et al (2007).…”

Renal Kallikrein Excretion and Epigenetics in Human Acute Kidney Injury: Expression, Mechanisms and Consequences

“…Osteogenic differentiation of mesenchymal cells towards osteoprogenitor and osteoblastic cells is regulated by several mechanisms, including DNA methylation. Kang et al demonstrated that promoter methylation changes during mesenchymal cell differentiation [50]. Likewise, it has been proposed that active demethylation of gene promoters (i.e., osteocalcin, osterix, or Runx2), via GADD45-dependent mechanisms, is involved in the ostegenic differentiation of mesenchymal cells [51].…”