Biomaterial Database

In vitro biotransformation of 1,1-dichloroethylene by hepatic cytochrome P-450 2E1 in mice. 1994

R P Lee, and P G Forkert

Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, Canada.

1,1-Dichloroethylene (DCE) is hepatotoxic in mice and its cytotoxic effects are associated with cytochrome P-450 (P450)-dependent formation of metabolite(s) that bind covalently to tissue macromolecules. Our goal was to investigate effects of DCE on P450 in liver microsomes. Specific objectives were to examine 1) inactivation of P450 by DCE and to determine if during this inactivation the heme and/or apoprotein moieties are destroyed and 2) isozyme-selective biotransformation of DCE by P450. Our results showed significant reduction of P450 content in reactions containing DCE and microsomes from untreated (30%) or phenobarbital-treated (20%) mice. Maximal reduction (50%) of P450 was evoked by DCE in reactions catalyzed by microsomes from acetone-treated mice. Alterations in heme levels were not detected in any microsomal preparation incubated in the presence of DCE. Significant inhibition of p-nitro-phenol hydroxylation was found in microsomes incubated previously with DCE and was most pronounced in acetone-treated mice, as compared to control and phenobarbital-treated mice. DCE did not cause inhibition of 7-pentoxyresorufin-O-dealkylation in any microsomal preparation. Immunoinhibition with an anti-2E1 antibody abolished the observed inhibition of p-nitrophenol hydroxylation. Densitometric scanning of protein immunoblots using an anti-2E1 antibody revealed a 40% decrease in microsomes reacted with DCE, whereas no change was observed in immunoblots prepared with an anti-2B antibody. These results showed that 1) biotransformation of DCE is catalyzed by the 2E1 and not by the 2B enzyme and 2) DCE inactivates P450 by destruction of the apoprotein rather than the heme moieties.

UI	MeSH Term	Description	Entries
D007150	Immunohistochemistry	Histochemical localization of immunoreactive substances using labeled antibodies as reagents.	Immunocytochemistry,Immunogold Techniques,Immunogold-Silver Techniques,Immunohistocytochemistry,Immunolabeling Techniques,Immunogold Technics,Immunogold-Silver Technics,Immunolabeling Technics,Immunogold Silver Technics,Immunogold Silver Techniques,Immunogold Technic,Immunogold Technique,Immunogold-Silver Technic,Immunogold-Silver Technique,Immunolabeling Technic,Immunolabeling Technique,Technic, Immunogold,Technic, Immunogold-Silver,Technic, Immunolabeling,Technics, Immunogold,Technics, Immunogold-Silver,Technics, Immunolabeling,Technique, Immunogold,Technique, Immunogold-Silver,Technique, Immunolabeling,Techniques, Immunogold,Techniques, Immunogold-Silver,Techniques, Immunolabeling
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D008297	Male		Males
D008815	Mice, Inbred Strains	Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations, or by parent x offspring matings carried out with certain restrictions. All animals within an inbred strain trace back to a common ancestor in the twentieth generation.	Inbred Mouse Strains,Inbred Strain of Mice,Inbred Strain of Mouse,Inbred Strains of Mice,Mouse, Inbred Strain,Inbred Mouse Strain,Mouse Inbred Strain,Mouse Inbred Strains,Mouse Strain, Inbred,Mouse Strains, Inbred,Strain, Inbred Mouse,Strains, Inbred Mouse
D008862	Microsomes, Liver	Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough.	Liver Microsomes,Liver Microsome,Microsome, Liver
D010089	Oxidoreductases, N-Demethylating		N-Demethylase,N-Demethylases,Oxidoreductases, N Demethylating,Demethylating Oxidoreductases, N,N Demethylase,N Demethylases,N Demethylating Oxidoreductases,N-Demethylating Oxidoreductases
D003577	Cytochrome P-450 Enzyme System	A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism.	Cytochrome P-450,Cytochrome P-450 Enzyme,Cytochrome P-450-Dependent Monooxygenase,P-450 Enzyme,P450 Enzyme,CYP450 Family,CYP450 Superfamily,Cytochrome P-450 Enzymes,Cytochrome P-450 Families,Cytochrome P-450 Monooxygenase,Cytochrome P-450 Oxygenase,Cytochrome P-450 Superfamily,Cytochrome P450,Cytochrome P450 Superfamily,Cytochrome p450 Families,P-450 Enzymes,P450 Enzymes,Cytochrome P 450,Cytochrome P 450 Dependent Monooxygenase,Cytochrome P 450 Enzyme,Cytochrome P 450 Enzyme System,Cytochrome P 450 Enzymes,Cytochrome P 450 Families,Cytochrome P 450 Monooxygenase,Cytochrome P 450 Oxygenase,Cytochrome P 450 Superfamily,Enzyme, Cytochrome P-450,Enzyme, P-450,Enzyme, P450,Enzymes, Cytochrome P-450,Enzymes, P-450,Enzymes, P450,Monooxygenase, Cytochrome P-450,Monooxygenase, Cytochrome P-450-Dependent,P 450 Enzyme,P 450 Enzymes,P-450 Enzyme, Cytochrome,P-450 Enzymes, Cytochrome,Superfamily, CYP450,Superfamily, Cytochrome P-450,Superfamily, Cytochrome P450
D004000	Dichloroethylenes	Toxic chlorinated unsaturated hydrocarbons. Include both the 1,1- and 1,2-dichloro isomers. Both isomers are toxic, but 1,1-dichloroethylene is the more potent CNS depressant and hepatotoxin. It is used in the manufacture of thermoplastic polymers.	Vinylidene Chlorides,Chlorides, Vinylidene
D006418	Heme	The color-furnishing portion of hemoglobin. It is found free in tissues and as the prosthetic group in many hemeproteins.	Ferroprotoporphyrin,Protoheme,Haem,Heme b,Protoheme IX
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia