RNA-Sequencing Quantification of Hepatic Ontogeny and Tissue Distribution of mRNAs of Phase II Enzymes in Mice

Abstract

Phase II conjugating enzymes play key roles in the metabolism of xenobiotics. In the present study, RNA sequencing was used to elucidate hepatic ontogeny and tissue distribution of mRNA expression of all major known Phase II enzymes, including enzymes involved in glucuronidation, sulfation, glutathione conjugation, acetylation, methylation, and amino acid conjugation, as well as enzymes for the synthesis of Phase II cosubstrates, in male C57BL/6J mice. Livers from male C57BL/6J mice were collected at 12 ages from prenatal to adulthood. Many of these Phase II enzymes were expressed at much higher levels in adult livers than in perinatal livers, such as Ugt1a6b, -2a3, -2b1, -2b5, -2b36, -3a1, and -3a2; Gsta1, -m1, -p1, -p2, and -z1; mGst1; Nat8; Comt; Nnmt; Baat; Ugdh; and Gclc. In contrast, hepatic mRNA expression of a few Phase II enzymes decreased during postnatal liver development, such as mGst2, mGst3, Gclm, and Mat2a. Hepatic expression of certain Phase II enzymes peaked during the adolescent stage, such as Ugt1a1, Sult1a1, Sult1c2, Sult1d1, Sult2as, Sult5a1, Tpmt, Glyat, Ugp2, and Mat1a. In adult mice, the total transcripts for Phase II enzymes were comparable in liver, kidney, and small intestine; however, individual Phase II enzymes displayed marked tissue specificity among the three organs. In conclusion, this study unveils for the first time developmental changes in mRNA abundance of all major known Phase II enzymes in mouse liver, as well as their tissuespecific expression in key drug-metabolizing organs. The age-and tissue-specific expression of Phase II enzymes indicate that the detoxification of xenobiotics is highly regulated by age and cell type.

RNA Sequencing Quantification of Xenobiotic-Processing Genes in Various Sections of the Intestine in Comparison to the Liver of Male Mice

“…The present findings of XPG expression in the liver are consistent with previous RNA-Seq reports in adult male mice (Cui et al, 2012;Peng et al, 2012Peng et al, , 2013Lu et al, 2013). The present study is novel because it has unveiled the true quantification of XPGs in various sections of the intestine, in comparison with that in liver.…”

“…The result of RNA-Seq is expressed as fragments per kilobase of exon per million reads mapped (FPKM), which normalizes the sequencing depths between different samples and sizes between various genes, allowing a direct comparison of various transcripts on a genome-wide scale (Malone and Oliver, 2011). We have previously conducted RNA-Seq experiments on the ontogeny of various XPGs in mouse livers (Cui et al, 2012;Peng et al, 2012Peng et al, , 2013Lu et al, 2013;Selwyn et al, 2015), but a systematic characterization of the XPGs in various sections of the intestine in comparison with liver tissue is lacking.…”

Ontogenic expression of human carboxylesterase-2 and cytochrome P450 3A4 in liver and duodenum: Postnatal surge and organ-dependent regulation

“…We and other investigators have shown that the expression of biotransformation genes is developmentally regulated in rodents and humans (Morgan et al, 1994; Yang et al, 2009; Hines, 2013; Lu, 2013; Peng et al, 2013). Based on immunoblotting analysis (Morgan et al, 1994), one to two week old rats express no hydrolase A or B, two major rat carboxylesterases.…”

RNA-Sequencing Quantification of Hepatic Ontogeny of Phase-I Enzymes in Mice

“…More importantly, RNA-Seq quantifies the true abundance of mRNA molecules in biologic samples and enables comparison of the expression of all genes (Malone and Oliver, 2011). We have reported that RNA-Seq can reveal ontogenic patterns of P450s (Peng et al, 2012), phase-II enzymes (Lu et al, 2013), transporters (Cui et al, 2012a), and epigenetic modifiers in the mouse liver during maturation.…”