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Localized methylation in the key regulator gene endothelin ‐ 1 is associated with cell type‐specific transcriptional silencing
Author(s) -
Vallender Tammy W.,
Lahn Bruce T.
Publication year - 2006
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2006.07.017
Subject(s) - dna methylation , biology , gene silencing , regulation of gene expression , microbiology and biotechnology , microarray analysis techniques , gene expression , methylation , gene , transcriptional regulation , promoter , epigenetics of physical exercise , genetics
DNA methylation can contribute to the stable transcriptional silencing of mammalian genes. Often times, these genes are important developmental regulators, and their silencing in cell types where they are not supposed to be active is important for the phenotypic stability of the cells. To identify key developmental regulator genes whose expression in terminally differentiated cells may be inhibited by DNA methylation, mouse dermal fibroblasts were demethylated with 5‐aza‐2′‐deoxycytidine, and changes in gene expression monitored by microarray analysis. Endothelin ‐ 1 ( Et1 or Edn1 ), which encodes a cytokine with diverse regulatory functions, was among the genes upregulated following demethylation. We found that CpG dinucleotides within a short region in intron 1 of the gene have dramatically higher levels of methylation in Et1 ‐non‐expressing fibroblasts and chondrocytes as compared to the Et1 ‐expressing mouse cell line, mIMCD‐3. Strong evolutionary conservation of this region implies its role in the cis ‐regulation of Et1 transcription. To confirm that should Et1 in dermal fibroblasts become aberrantly activated, it could indeed lead to the dysregulation of many downstream genes, we exposed fibroblasts to exogenous ET1 peptide and assayed for transcriptional changes by microarray. ET1 treatment resulted in significant expression changes – primarily downregulation – of a significant number of genes. In particular, Tgfβ2 and Tgfβ3 were among the downregulated genes, which in turn alter the expression status of their many target genes. These data suggest that the stable silencing of Et1 through its associated DNA methylation in intron 1 is critical for the developmental stability of dermal fibroblasts, and perhaps other cell types as well.