Cloning and expression of a novel catechol-O-methyltransferase in common marmosets

Expression of functional sulfotransferases (SULT) 1A1, 1A3, 1B1, 1C2, 1E1, and 2A1 in common marmosets

Cytosolic sulfotransferases (SULTs), which mediate the conjugation of drugs with 3'-phosphoadenosine-5'-phosphosulfate, have been characterized in humans and cynomolgus monkeys. However, SULTs remain to be evaluated in common marmosets, a species of non-human primate often employed in drug metabolism and pharmacokinetic studies of endogenous and exogenous compounds. In this study, marmoset SULT1A1, 1A3, 1B1, 1C2, 1E1, and 2A1 cDNAs were isolated and characterized, based on genome data. The deduced amino acid sequences of these marmoset SULT cDNAs had high identities (90-95%) with their human orthologs, except for marmoset SULT2A1, which was only 81% identical to human SULT2A1. The amino acid sequences of the orthologs of these six SULTs in marmosets, monkeys, and humans were closely clustered in a phylogenetic tree. The structures and genomic organizations of marmoset SULT genes were similar to those of their human orthologs. Among the five marmoset tissues analyzed, SULT mRNAs showed typical expression patterns. The most abundant SULT mRNAs were SULT1B1 in liver, small intestine, and kidney; SULT1E1 in lung; and SULT1A3 in brain. Recombinant marmoset SULT1A1, 1A3, 1B1, 1C2, 1E1, and 2A1 proteins expressed in bacterial cytosolic fractions mediated sulfate conjugations with 3'-phosphoadenosine-5'-phosphosulfate of the following typical human SULT substrates: dopamine, 1-naphthol, p-nitrophenol, estradiol, and dehydroepiandrosterone. Taken together, these wide-ranging results suggest functional and molecular similarities of SULTs among marmosets, monkeys, and humans.

Utility of Common Marmoset (Callithrix jacchus) Embryonic Stem Cells in Liver Disease Modeling, Tissue Engineering and Drug Metabolism

The incidence of liver disease is increasing significantly worldwide and, as a result, there is a pressing need to develop new technologies and applications for end-stage liver diseases. For many of them, orthotopic liver transplantation is the only viable therapeutic option. Stem cells that are capable of differentiating into all liver cell types and could closely mimic human liver disease are extremely valuable for disease modeling, tissue regeneration and repair, and for drug metabolism studies to develop novel therapeutic treatments. Despite the extensive research efforts, positive results from rodent models have not translated meaningfully into realistic preclinical models and therapies. The common marmoset Callithrix jacchus has emerged as a viable non-human primate model to study various human diseases because of its distinct features and close physiologic, genetic and metabolic similarities to humans. C. jacchus embryonic stem cells (cjESC) and recently generated cjESC-derived hepatocyte-like cells (cjESC-HLCs) could fill the gaps in disease modeling, liver regeneration and metabolic studies. They are extremely useful for cell therapy to regenerate and repair damaged liver tissues in vivo as they could efficiently engraft into the liver parenchyma. For in vitro studies, they would be advantageous for drug design and metabolism in developing novel drugs and cell-based therapies. Specifically, they express both phase I and II metabolic enzymes that share similar substrate specificities, inhibition and induction characteristics, and drug metabolism as their human counterparts. In addition, cjESCs and cjESC-HLCs are advantageous for investigations on emerging research areas, including blastocyst complementation to generate entire livers, and bioengineering of discarded livers to regenerate whole livers for transplantation.

Survey of Drug Oxidation Activities in Hepatic and Intestinal Microsomes of Individual Common Marmosets, a New Nonhuman Primate Animal Model

BACKGROUND

Common marmosets (Callithrix jacchus) are potentially useful nonhuman primate models for preclinical studies. Information for major drug-metabolizing cytochrome P450 (P450) enzymes is now available that supports the use of this primate species as an animal model for drug development. Here, we collect and provide an overview of information on the activities of common marmoset hepatic and intestinal microsomes with respect to 28 typical human P450 probe oxidations.

RESULTS

Marmoset P450 2D6/8-dependent R-metoprolol O-demethylation activities in hepatic microsomes were significantly correlated with those of midazolam 1'- and 4-hydroxylations, testosterone 6β-hydroxylation, and progesterone 6β-hydroxylation, which are probe reactions for marmoset P450 3A4/5/90. In marmosets, the oxidation activities of hepatic microsomes and intestinal microsomes were roughly comparable for midazolam and terfenadine. Overall, multiple forms of marmoset P450 enzymes in livers and intestines had generally similar substrate recognition functionalities to those of human and/or cynomolgus monkey P450 enzymes.

CONCLUSION

The marmoset could be a model animal for humans with respect to the first-pass extraction of terfenadine and related substrates. These findings provide a foundation for understanding individual pharmacokinetic and toxicological results in nonhuman primates as preclinical models and will help to further support understanding of the molecular mechanisms of human P450 function.