Monkeys are widely used as a primate model to study drug metabolism because they generally show a metabolic pattern similar to humans. However, the paucity of information on cytochrome P450 (P450) genes has hampered a deep understanding of drug metabolism in the monkey. In this study, we report identification of the CYP2C76 cDNA newly identified in cynomolgus monkey and characterization of this CYP2C along with cynomolgus CYP2C20, CYP2C43, and CYP2C75. The CYP2C76 cDNA contains the open reading frame encoding a protein of 489 amino acids that are only approximately 80% identical to any human or monkey P450 cDNAs. Gene and protein expression of CYP2C76 was confirmed in the liver of cynomolgus and rhesus monkeys but not in humans or the great apes. Moreover, CYP2C76 is located at the end of the CYP2C gene cluster in the monkey genome, the region of which corresponds to the intergenic region adjacent to the CYP2C cluster in the human genome, strongly indicating that this gene does not have the ortholog in humans. Among the four CYP2C genes expressing predominantly in the liver, the expression level of CYP2C76 was the greatest, suggesting that CYP2C76 is a major CYP2C in the monkey liver. Assays for the capacity of CYP2C76 to metabolize drugs using several substrates typical for human CYP2Cs revealed that CYP2C76 showed unique metabolic activity. These results suggest that CYP2C76 contributes to overall drug-metabolizing activity in the monkey liver and might account for species difference occasionally seen in drug metabolism between monkeys and humans.Cytochrome P450s (P450s) are one of the most important drug-metabolizing enzymes and form a superfamily consisting of a large number of subfamilies (Nelson et al., 1996(Nelson et al., , 2004. The cDNA sequences encoding P450s have been reported for many species of not only mammals but also birds, insects, plants, bacteria, and others (see http://drnelson. utmem.edu/CytochromeP450.html). In humans, 57 functional genes have been identified to date (Nelson et al., 2004). The human CYP2C subfamily, comprising CYP2C8, CYP2C9, CYP2C18, and CYP2C19, is essential in metabolizing approximately 20% of all prescribed drugs, including tolbutamide, phenytoin, warfarin, and ibuprofen (Goldstein, 2001). The CYP2C subfamily consists of multiple members in each mammalian species, including 15 in mice, 12 in rats, and 9 in rabbits (for the latest information, see http://drnelson.utmem.edu/CytochromeP450.html). Between humans and rodents, the number of the subfamily members is different, and none of the CYP2Cs seems to show a clear orthologous relationship between the two species, suggesting that the data from rodents must be cautiously interpreted and extrapolated to humans (Nelson et al., 2004).For monkeys, which generally mean Old or New World monkeys, three CYP2C cDNAs have been identified in the macaque and cynomolgus (Macaca fascicularis) and rhesus (Macaca mulatta) monkeys. Two sequences have been published including cynomolgus CYP2C20 (Komori et al., 1992) and rhesus CYP...

Macaca fascicularis and Macaca mulatta are two of the most commonly used laboratory macaques, yet their genetic differences at a genome-wide level remain unclear. We analysed the multilocus DNA sequence data of 54 autosomal loci obtained from M. fascicularis samples from three different geographic origins and M. mulatta samples of Burmese origin. M. fascicularis shows high nucleotide diversity, four to five times higher than humans, and a strong geographic population structure between Indonesian-Malaysian and Philippine macaques. The pattern of divergence and polymorphism between M. fascicularis and M. mulatta shows a footprint of genetic exchange not only within their current hybrid zone but also across a wider range for more than 1 million years. However, genetic admixture may not be a random event in the genome. Whereas randomly selected genic and intergenic regions have the same evolutionary dynamics between the species, some cytochrome oxidase P450 (CYP) genes (major chemical metabolizing genes and potential target genes for local adaptation) have a significantly larger species divergence than other genes. By surveying CYP3A5 gene sequences of more than a hundred macaques, we identified three nonsynonymous single nucleotide polymorphisms that were highly differentiated between the macaques. The mosaic pattern of species divergence in the genomes may be a consequence of genetic differentiation under ecological adaptation and may be a salient feature in the genomes of nascent species under parapatry.

(R)-Thalidomide was oxidized to 5-hydroxythalidomide and 5’-hydroxythalidomide by NADPH-fortified liver microsomes from humans and monkeys. (R)-Thalidomide was hydroxylated more efficiently than (S)-thalidomide. Recombinant human P450s 3A4, 3A5, and 3A7 and monkey P450s 3A8 and 3A5 (co-expressed with NADPH-P450 reductase in bacterial membranes) also catalyzed (R)-thalidomide 5-hydroxylation. Purified human P450s 2C19, 3A4, and 3A5 mediated (R)-thalidomide 5-hydroxylation at similar rates in reconstituted systems. P450 2C19 showed a rather non-saturable substrate-velocity curve; however, P450s 3A4 and 3A5 showed sigmoidal curves. P450 also oxidized 5-hydroxythalidomide to an epoxide or dihydroxy compound. Liquid chromatography-mass spectrometry analysis revealed formation of a glutathione conjugate from (R)- and (S)-5-hydroxythalidomide, catalyzed by liver microsomal P450s 3A4 and 3A5 in the presence of glutathione (assigned as a conjugate of 5-hydroxythalidomide formed on the phenyl ring). These results indicate that human P450s 3A4 and 3A5 mediate thalidomide 5-hydroxylation and further oxidation leading to a glutathione conjugate, which may be of relevance in the pharmacological and toxicological actions of thalidomide.