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Decker M, Arand M, Cronin A. Mammalian epoxide hydrolases in xenobiotic metabolism and signalling. Arch Toxicol 2009; 83:297-318. [PMID: 19340413 DOI: 10.1007/s00204-009-0416-0] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Accepted: 02/16/2009] [Indexed: 12/14/2022]
Abstract
Epoxide hydrolases catalyse the hydrolysis of electrophilic--and therefore potentially genotoxic--epoxides to the corresponding less reactive vicinal diols, which explains the classification of epoxide hydrolases as typical detoxifying enzymes. The best example is mammalian microsomal epoxide hydrolase (mEH)-an enzyme prone to detoxification-due to a high expression level in the liver, a broad substrate selectivity, as well as inducibility by foreign compounds. The mEH is capable of inactivating a large number of structurally different, highly reactive epoxides and hence is an important part of the enzymatic defence of our organism against adverse effects of foreign compounds. Furthermore, evidence is accumulating that mammalian epoxide hydrolases play physiological roles other than detoxification, particularly through involvement in signalling processes. This certainly holds true for soluble epoxide hydrolase (sEH) whose main function seems to be the turnover of lipid derived epoxides, which are signalling lipids with diverse functions in regulatory processes, such as control of blood pressure, inflammatory processes, cell proliferation and nociception. In recent years, the sEH has attracted attention as a promising target for pharmacological inhibition to treat hypertension and possibly other diseases. Recently, new hitherto uncharacterised epoxide hydrolases could be identified in mammals by genome analysis. The expression pattern and substrate selectivity of these new epoxide hydrolases suggests their participation in signalling processes rather than a role in detoxification. Taken together, epoxide hydrolases (1) play a central role in the detoxification of genotoxic epoxides and (2) have an important function in the regulation of physiological processes by the control of signalling molecules with an epoxide structure.
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Affiliation(s)
- Martina Decker
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurer Str. 190, 8057 Zurich, Switzerland
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Miyata M, Kudo G, Lee YH, Yang TJ, Gelboin HV, Fernandez-Salguero P, Kimura S, Gonzalez FJ. Targeted disruption of the microsomal epoxide hydrolase gene. Microsomal epoxide hydrolase is required for the carcinogenic activity of 7,12-dimethylbenz[a]anthracene. J Biol Chem 1999; 274:23963-8. [PMID: 10446164 DOI: 10.1074/jbc.274.34.23963] [Citation(s) in RCA: 151] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Microsomal epoxide hydrolase (mEH) is a conserved enzyme that is known to hydrolyze many drugs and carcinogens, and a few endogenous steroids and bile acids. mEH-null mice were produced and found to be fertile and have no phenotypic abnormalities thus indicating that mEH is not critical for reproduction and physiological homeostasis. mEH has also been implicated in participating in the metabolic activation of polycyclic aromatic hydrocarbon carcinogens. Embryonic fibroblast derived from the mEH-null mice were unable to produce the proximate carcinogenic metabolite of 7,12-dimethylbenz[a]anthracene (DMBA), a widely studied experimental prototype for the polycylic aromatic hydrocarbon class of chemical carcinogens. They were also resistant to DMBA-mediated toxicity. Using the two-stage initiation-promotion skin cancer bioassay, the mEH-null mice were found to be highly resistant to DMBA-induced carcinogenesis. In a complete carcinogenesis bioassay, the mEH mice were totally resistant to tumorigenesis. These data establish in an intact animal model that mEH is a key genetic determinant in DMBA carcinogenesis through its role in production of the ultimate carcinogenic metabolite of DMBA, the 3,4-diol-1,2-epoxide.
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Affiliation(s)
- M Miyata
- Laboratory of Metabolism, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA
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Santos J, Cole Y, Pellicer A. Phylogenetic relationships among laboratory and wild-origin Mus musculus strains on the basis of genomic DNA RFLPs. Mamm Genome 1993; 4:485-92. [PMID: 7906967 DOI: 10.1007/bf00364782] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Genetic distance measures between the laboratory mouse strains C57BL/6J and RF/J and the wild-origin Mus musculus mouse strains CAST/Ei, MOLF/Ei, POSCH I, and CZECH II were estimated by allelic patterns revealed by RFLP analysis. These results suggest phylogenetic relationships indicating that the mouse strains related to the subspecies M.m. domesticus (RF/J, POSCH I and C57BL/6J) are more closely related to the CAST/Ei strain (derived from M.m. castaneus) than to the strains CZECH II (M.m. musculus) and MOLF/Ei (M.m. molossinus). Furthermore, the hybrid strain C57BL/6J is more closely related to POSCH I (M.m. poschiavinus) than to RF/J as calculated by the method distance measures of Cavalli-Sforza and Edwards (Evolution 21,550, 1967), Nei's minimum (Am. Natural. 106,283, 1972) and unbiased minimum (Genetics 89,583, 1978), Edwards (Biometrics 27,873, 1971; Genetic Distance, p. 41, 1974) and Rogers modified (1986).
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Affiliation(s)
- J Santos
- Department of Pathology, New York University School of Medicine, New York 10016
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Eugster HP, Sengstag C, Hinnen A, Meyer UA, Würgler FE. Heterologous expression of human microsomal epoxide hydrolase in Saccharomyces cerevisiae. Study of the valpromide-carbamazepine epoxide interaction. Biochem Pharmacol 1991; 42:1367-72. [PMID: 1930259 DOI: 10.1016/0006-2952(91)90447-d] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A cDNA of human microsomal epoxide hydrolase (hmEH) was constitutively and inducibly expressed in Saccharomyces cerevisiae. The heterologous enzyme was located mainly in the microsomal fraction of yeast cells. Yeast microsomes containing hmEH exerted styrene oxide hydrolase activity (Km = 300 microM; Vmax = 22 nmol/mg min) as well as carbamazepine epoxide hydrolase activity. The hmEH catalysed exclusively the formation of carbamazepine-10,11-transdihydrodiol, since no carbamazepine-10,11-cisdihydrodiol was detected. Inhibition studies using these microsomes revealed unequivocally hmEH as the target for inhibition by the antiepileptic drug valpromide. A Ki value of 27 microM was determined for the inhibitor valpromide with styrene oxide as substrate. For carbamazepine epoxide, a Ki value of 8.6 microM was obtained, which is well in line with data published for hmEH determined with human liver microsomes. Our results demonstrate the potential of heterologous gene expression in S. cerevisiae and its application to the in vitro study of pharmacological and toxicological problems.
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Affiliation(s)
- H P Eugster
- Institute of Toxicology, Swiss Federal Institute of Technology, Basel
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Simmons DL, Kasper CB. Quantitation of mRNAs specific for the mixed-function oxidase system in rat liver and extrahepatic tissues during development. Arch Biochem Biophys 1989; 271:10-20. [PMID: 2469391 DOI: 10.1016/0003-9861(89)90250-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Evaluation of ontogenetic expression of the cytochrome P450PCN and cytochrome P450b gene families as well as the NADPH-cytochrome P450 oxidoreductase and epoxide hydrolase genes in Holtzmann rats showed that basal levels of mRNAs encoding these enzymes could be detected in most tissues. Distinct developmental patterns of mRNA expression are evident for these four proteins in liver and extrahepatic tissues. Levels of cytochrome P450b-like mRNA were comparable in adult lung and liver, while cytochrome P450PCN-homologous mRNA exhibited low levels in lung and approximately 100-fold higher levels in liver. Cytochrome P450PCN-homologous mRNA also reached substantial levels in adult intestine, and was also present in placenta, where it increased approximately 4-fold 24 h before birth. Epoxide hydrolase mRNA was demonstrated to be highest in liver followed by kidney, lung, and intestine but was extremely low in brain. NADPH-cytochrome P450 oxidoreductase mRNA in kidney, lung, prostate, adrenal, and intestine exhibited levels comparable to that found in liver; however, the pattern of expression for oxidoreductase mRNA was unique in that levels declined at maturity in liver, kidney, and intestine but not in lung and brain. Development of mixed-function oxidase and epoxide hydrolase activities in liver was distinct from that in other tissues in that mRNAs for all four proteins rose dramatically after parturition. Testis from immature males demonstrated low levels of all the mRNAs assayed, which ranged from 20% (oxidoreductase) to less than 1% (cytochrome P450PCN and epoxide hydrolase) of the levels found in liver.
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Affiliation(s)
- D L Simmons
- McArdle Laboratory for Cancer Research, University of Wisconsin, Madison 53706
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Induction of the hepatic mixed-function oxidase system by synthetic glucocorticoids. Transcriptional and post-transcriptional regulation. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(19)75930-4] [Citation(s) in RCA: 95] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Porter TD, Beck TW, Kasper CB. Complementary DNA and amino acid sequence of rat liver microsomal, xenobiotic epoxide hydrolase. Arch Biochem Biophys 1986; 248:121-9. [PMID: 3755318 DOI: 10.1016/0003-9861(86)90408-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The coding nucleotide sequence for rat liver microsomal, xenobiotic epoxide hydrolase was determined from two overlapping cDNA clones, which together contain 1750 nucleotides complementary to epoxide hydrolase mRNA. The single open reading frame of 1365 nucleotides codes for a 455 amino acid polypeptide with a molecular weight of 52,581. The deduced amino acid composition agrees well with those determined by direct amino acid analysis of the rat protein, and the amino acid sequence is 81% identical to that of rabbit epoxide hydrolase. Analysis of codon usage for epoxide hydrolase, and that of rabbit epoxide hydrolase. Analysis of codon usage for epoxide hydrolase, and comparison to codon usage for NADPH-cytochrome P-450 oxidoreductase and cytochromes P-450b, P-450d, and P-450PCN, suggest that epoxide hydrolase is more conserved than cytochromes P-450b and P-450PCN; comparison of the extent of sequence conservation for 12 homologous proteins between the rat and rabbit, including cytochrome P-450b, supports this hypothesis, and indicates that much of epoxide hydrolase is constrained to maintain its hydrophobic character, consistent with its intramembranous location. The predicted membrane topology of epoxide hydrolase delineates 6 membrane-spanning segments, less than the 8 or 10 predicted for two cytochrome P-450 isozymes; the lower number of membrane-spanning segments predicted for epoxide hydrolase correlates with its lesser dependence on the membrane for maintenance of its tertiary structure and catalytic activity.
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Simmons DL, Lalley PA, Kasper CB. Chromosomal assignments of genes coding for components of the mixed-function oxidase system in mice. Genetic localization of the cytochrome P-450PCN and P-450PB gene families and the nadph-cytochrome P-450 oxidoreductase and epoxide hydratase genes. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)89763-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Kimura S, Gonzalez FJ, Nebert DW. The murine Ah locus. Comparison of the complete cytochrome P1-450 and P3-450 cDNA nucleotide and amino acid sequences. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(18)90569-7] [Citation(s) in RCA: 145] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Nepokroeff CM, Adachi K, Yan C, Porter JW. Cloning of DNA complementary to rat liver fatty acid synthetase mRNA. ACTA ACUST UNITED AC 1984; 140:441-5. [PMID: 6546917 DOI: 10.1111/j.1432-1033.1984.tb08122.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Clones, containing DNA complementary (cDNA) to rat liver fatty acid synthetase mRNA, were constructed and identified. cDNA of these clones was then used as a probe to quantify mRNA. The cDNA was synthesized to partially purified rat liver fatty acid synthetase mRNA. Double-stranded cDNA was then prepared and inserted into the PstI site of pBR322 using oligo(dG) X oligo(dC) tailing. Initial selection of the clones was by differential colony hybridization employing [32P]cDNA synthesized from poly(A)-rich mRNA, enriched and non-enriched in fatty acid synthetase mRNA, as probes. Plasmids, containing specific sequences complementary to the fatty acid synthetase mRNA, were identified by hybrid-arrest translation. Cloned cDNA inserts ranged from 300 to 1400 base pairs. Cloned cDNA was employed to probe for mRNA in hybridizations via the dot-blot method. These studies demonstrated an increase in fatty acid synthetase mRNA during dietary induction, which suggests that regulation may involve changes in transcription or changes in post-transcriptional processing of the mRNA.
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Molecular cloning and nucleotide sequence of a cDNA clone coding for the cell attachment domain in human fibronectin. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)44437-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Hardwick JP, Gonzalez FJ, Kasper CB. Cloning of DNA complementary to cytochrome P-450 induced by pregnenolone-16 alpha-carbonitrile. Characterization of its mRNA, gene, and induction response. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)44622-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Hardwick JP, Gonzalez FJ, Kasper CB. Transcriptional regulation of rat liver epoxide hydratase, NADPH-Cytochrome P-450 oxidoreductase, and cytochrome P-450b genes by phenobarbital. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(20)82030-4] [Citation(s) in RCA: 132] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Gonzalez FJ, Samore M, McQuiddy P, Kasper CB. Effects of 2-acetylaminofluorene and N-hydroxy-2-acetylaminofluorene on the cellular levels of epoxide hydratase, cytochrome P-450b, and NADPH-cytochrome c (P-450) oxidoreductase messenger ribonucleic acids. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)33928-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Gonzalez FJ, Kasper CB. Cloning of DNA complementary to rat liver NADPH-cytochrome c (P-450) oxidoreductase and cytochrome P-450b mRNAs. Evidence that phenobarbital augments transcription of specific genes. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(19)83872-3] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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18
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DuBois GC, Appella E, Ryan DE, Jerina DM, Levin W. Human hepatic microsomal epoxide hydrolase. A structural comparison with the rat enzyme. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)34981-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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