Generation of mice transgenic for human CYP2C18 and CYP2C19: characterization of the sexually dimorphic gene and enzyme expression.
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.
Löfgren
Susanne
S
Safety Assessment, AstraZeneca Research and Development, Södertälje, Sweden.
Baldwin
R Michael
RM
Hiratsuka
Masahiro
M
Lindqvist
Annelie
A
Carlberg
Anne
A
Sim
Sarah C
SC
Schülke
Meint
M
Snait
Michael
M
Edenro
Anne
A
Fransson-Steen
Ronny
R
Terelius
Ylva
Y
Ingelman-Sundberg
Magnus
M
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D065731:Cytochrome P-450 CYP2C19; D005260:Female; D018628:Gene Dosage; D015870:Gene Expression; D006801:Humans; D008297:Male; D008617:Mephenytoin / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic / Q000235:genetics*; D008861:Microsomes / Q000378:metabolism; D009853:Omeprazole; D012333:RNA, Messenger / Q000378:metabolism; D012727:Sex Characteristics; D014018:Tissue Distribution
D012333:RNA, Messenger; D001189:Aryl Hydrocarbon Hydroxylases; C082185:CYP2C18 protein, human; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D009853:Omeprazole; D008617:Mephenytoin