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A new function for methyl CpG: Creating a C/EBPα binding site & mediating tissue‐specific gene expression
Author(s) -
Chatterjee Raghunath,
Rishi Vikas,
Rozenberg Julian,
Bhattacharya Paramita,
Glass Kimberly,
Zhao Jianfei,
Vinson Charles
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.lb56
Subject(s) - ccaat enhancer binding proteins , dna methylation , promoter , microbiology and biotechnology , methylation , cpg site , dna demethylation , transcription factor , gene expression , demethylation , epigenetics of physical exercise , regulation of gene expression , chemistry , enhancer , dna , gene , biology , binding site , reporter gene , dna binding protein , biochemistry
DNA methylation of the cytosine in the CpG dinucleotide is typically associated with gene inactivation. However, we observe that differentiation of primary mouse new‐born dermal fibroblasts into adipocytes activates genes with methylated promoters that are bound by the transcription factor CCAAT/enhancer‐binding‐protein‐α(C/EBPα). Experimental demethylation by either 5‐azacytidine treatment or by using siRNA to DNA methyltransferase1 (DNMT1) inhibits adipocyte differentiation. Differentiation inhibition caused by demethylation is mainly mediated by inhibition of both C/EBPα binding and activation of methylated promoters. Also, expressing of a dominant‐negative protein (A‐C/EBP) in the dermal fibroblasts that inhibits the DNA binding of C/EBP family members completely abolishes this differentiation. Specific C/EBP‐like and CRE‐like sequences are identified in tissue specific proximal promoters that are methylated in vivo, methylation enhances C/EBPα binding as observed by EMSA using pure protein, and need to be methylated for C/EBPα mediated activation as assayed by luciferase reporter. Similar results are observed when primary keratinocytes from new‐born mice are differentiated. These data identify a new function for methyl CpG, producing a DNA binding site for C/EBPα critical for activation of tissue specific gene expression.