Abstract
CYP2C19 is an important enzyme for human drug metabolism, and it also participates in the metabolism of endogenous substrates, whereas the CYP2C18 enzyme is not expressed in human liver despite high mRNA expression. Mice transgenic for the human CYP2C18 and CYP2C19 genes were generated. Quantitative mRNA analysis showed CYP2C18 and CYP2C19 transcripts in liver, kidneys, and heart to be expressed in a sexually dimorphic manner, with male mice having 2- to 100-fold higher levels. Transcript levels in the small intestine were somewhat higher than liver but were similar in both sexes. Transgene mRNA expression was much lower in lung and brain and least in the heart. Immunoblotting using an antipeptide antiserum, reactive with human CYP2Cs and mouse CYP2C70, revealed increased immunoreactive protein in liver microsomes from heterozygous transgenic male mice and a concomitant increase in 5′-hydroxylation of R-omeprazole and S-mephenytoin intrinsic clearance, consistent with CYP2C19 overexpression. A CYP2C18-specific antiserum showed that this enzyme was not expressed in livers or kidneys from heterozygous transgenic mice, but the antiserum had high affinity for recombinant CYP2C18 expressed in COS-7 cells. It is concluded that 1) both the CYP2C18 and CYP2C19 genes are subject to sexually dimorphic regulation in murine liver, kidney, and heart; 2) the CYP2C18 protein is not expressed in murine liver or kidney despite high levels of the corresponding mRNA; and 3) this transgenic model may be suitable for studying sex-dependent regulation of the human CYP2C genes and possibly serve as an in vivo model for CYP2C19-dependent drug metabolism.
Footnotes
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This research was in part supported by a grant from The Swedish Research council.
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S.L. and R.M.B. contributed equally to this work.
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Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
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doi:10.1124/dmd.107.019349.
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ABBREVIATIONS: P450, cytochrome P450; PCR, polymerase chain reaction; BAC, bacterial artificial chromosome; gDNA, genomic DNA; wt, wild-type; HPRT, hypoxanthine guanine phosphoribosyltransferase; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; DAPI, 4′,6-diamidino-2-phenylindole; bp, base pair; FISH, fluorescent in situ hybridization; hIL2, human IL2; mIL2, murine IL2; TBS, Tris-buffered saline; GH, growth hormone.
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↵1 Current affiliation: Department of Clinical Pharmacotherapeutics, Tohoku Pharmaceutical University, Sendai, Japan.
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↵2 Current affiliation: Medivir AB, Huddinge, Sweden.
- Received October 18, 2007.
- Accepted February 11, 2008.
- The American Society for Pharmacology and Experimental Therapeutics
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