PMC

Epigenetic mechanisms modify liver function. Dietary intake of methyl donors such as methionine and choline modifies hepatic inflammatory signaling pathways as well as the epigenetic marks regulating the expression of genes relevant to signaling pathways involved in hepatic steatosis, fibrosis, and carcinogenesis.

The nucleosome structure. DNA is tightly coiled in nucleosome repeating units (rendering captured with open-source java applet Jmol) composed of 147 base pairs of DNA wrapped around a histone octamer made of two copies of four core histones H2a, H2b, H3, and H4. The transcription of genes is modulated by how tightly the chromatin is packed, and epigenetic marks on histones (at specific lysines such as K9 and K4) and on DNA can modify this chromatin structure (see text). De novo methylation of the core nucleosome unit by DNA methyltransferase 3b (DNMT3b) and the mechanism of histone deacetylation by the methyl CpG-binding protein 2–histone deacetylase complex (MECP2–HDAC) are also depicted.