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. Author manuscript; available in PMC: 2014 Jul 1.
Published in final edited form as: Pulm Pharmacol Ther. 2012 Jul 16;26(1):75–85. doi: 10.1016/j.pupt.2012.07.002

Fig 1. Epigenetic regulation of gene expression.

Fig 1

A) Histone modifications occur on the N-terminal tails of the four core histones. Histone acetylation (Ac) by histone acetyltransferases (HATs) stabilizes the unmethylated DNA in an open chromatin conformation to allow for transcription factor (TF) binding, recruitment of RNA polymerase II (RNAPol II), mRNA expression and the synthesis of proteins coded by the coding DNA sequence (CDS). B) DNA methylation occurs when DNA nucleotide methyltransferase (Dnmt) adds methyl groups (CH3) to cytosine residues at CpG sites. Association of methylated DNA with histone deacetylases (HDAC) and histones methylated (Me) by histone methyltransferases (HMT) closes the chromatin structure to inhibit TF binding and silence gene expression.