Abstract
A mouse model termed Cpr-low (CL) was recently generated, in which the expression of the cytochrome P450 reductase (Cpr) gene was globally down-regulated. The decreased CPR expression was accompanied by phenotypical changes, including reduced embryonic survival, decreases in circulating cholesterol, increases in hepatic P450 expression, and female infertility (accompanied by elevated serum testosterone and progesterone levels). In the present study, a complementary mouse model [named reversible-CL (r-CL)] was generated, in which the reduced CPR expression can be reversed in an organ-specific fashion. The neo cassette, which was inserted into the last Cpr intron in r-CL mice, can be deleted by Cre recombinase, thus returning the structure of the Cpr gene (and hence CPR expression) to normal in Cre-expressing cells. All previously identified phenotypes of the CL mice were preserved in the r-CL mice. As a first application of the r-CL model, we have generated an extrahepatic-CL (xh-CL) mouse for testing of the functions of CPR-dependent enzymes in all extrahepatic tissues. The xh-CL mice, generated by mating of r-CL mice with albumin-Cre mice, had normal CPR expression in hepatocytes but down-regulated CPR expression elsewhere. They were indistinguishable from wild-type mice in body and liver weights, circulating cholesterol levels, and hepatic microsomal P450 expression and activities; however, they still showed elevated serum testosterone and progesterone levels and sterility in females. Embryonic lethality was prevented in males, but apparently not in females, indicating a critical role for fetal hepatic CPR-dependent enzymes in embryonic development, at least in males.
Footnotes
This work was supported in part by the National Institutes of Health National Cancer Institute [Grant CA092596]; the National Institutes of Health National Institute of Environmental Health Sciences [Grant ES007462] (to X.D.); and the National Institutes of Health National Institute of General Medical Sciences [Grant GM082978] (to Q.-Y.Z.).
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.110.167411.
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ABBREVIATIONS:
- CL
- Cpr-low
- r-CL
- reversible-CL
- xh-CL
- extrahepatic-CL
- CPR
- cytochrome P450 reductase
- POR
- P450 oxidoreductase
- LCN
- liver-specific Cpr-null
- NNK
- 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone
- NNAL
- 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol
- OM
- olfactory mucosa
- LC/MS
- liquid chromatography/mass spectrometry
- kbp
- kilobase pair
- WT
- wild type
- ES
- embryonic stem
- PCR
- polymerase chain reaction
- Alb
- albumin
- G418
- (2R,3S,4R,5R,6S)-5-amino-6-[(1R,2S,3S,4R,6S)-4,6-diamino-3-[(2R,3R,4R,5R)-3,5-dihydroxy-5-methyl-4-methylaminooxan-2-yl]oxy-2-hydroxycyclohexyl]oxy-2-(1-hydroxyethyl)oxane-3,4-diol
- En
- embryonic day n.
- Received February 18, 2010.
- Accepted April 5, 2010.
- Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics
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