Hepatic ontogeny and tissue distribution of mRNAs of epigenetic modifiers in mice using RNA-sequencing

Developmental regulation of gene expression is controlled by distinct epigenetic signatures catalyzed by various epigenetic modifiers. Little is known about the ontogeny and tissue distribution of these epigenetic modifiers. In the present study, we used a novel approach of RNA-sequencing to elucidate hepatic ontogeny and tissue distribution of mRNA expression of 142 epigenetic modifiers, including enzymes involved in DNA methylation/demethylation, histone acetylation/deacetylation, histone methylation/demethylation, histone phosphorylation and chromosome remodeling factors in male C57BL/6 mice. Livers from male C57BL/6 mice were collected at 12 ages from prenatal to adulthood. Many of these epigenetic modifiers were expressed at much higher levels in perinatal livers than adult livers, such as Dnmt1, Dnmt3a, Dnmt3b, Apobec3, Kat1, Ncoa4, Setd8, Ash2l, Dot1l, Cbx1, Cbx3, Cbx5, Cbx6, Ezh2, Suz12, Eed, Suv39h1, Suv420h2, Dek, Hdac1, Hdac2, Hdac7, Kdm2b, Kdm5c, Kdm7, Prmt1-5, Prmt7, Smarca4, Smarcb1, Chd4 and Ino80e. In contrast, hepatic mRNA expression of a few epigenetic modifiers increased during postnatal liver development, such as Smarca2, Kdm1b, Cbx7 and Chd3. In adult mice (60 d of age), most epigenetic modifiers were expressed at moderately (1-3-fold) higher levels in kidney and/or small intestine than liver. In conclusion, this study, for the first time, unveils developmental changes in mRNA abundance of all major known epigenetic modifiers in mouse liver. These data suggest that ontogenic changes in mRNA expression of epigenetic modifiers may play important roles in determining the addition and/or removal of corresponding epigenetic signatures during liver development.