title: Cytochrome P450 3A degradation in isolated rat hepatocytes: 26S proteasome inhibitors as probes.
abstract: Mechanism-based inactivation of liver microsomal cytochromes P450 3A (CYP 3A, P450s 3A) in vivo and/or in vitro, via heme modification of the protein, results in accelerated proteolytic degradation of the enzyme that is preceded by the ubiquitination of the protein, thereby implicating the ubiquitin-ATP-dependent 26S proteasomal system. In this study, this involvement is confirmed with the use of the proteasomal inhibitors aclarubicin and MG-132 as probes, in isolated rat hepatocytes treated with the P450 3A mechanism-based inactivator, 3,5-dicarbethoxy-2,6-dimethyl-4-ethyl-1, 4-dihydropyridine (DDEP). In addition, the findings reveal that during the course of this proteolysis, the endoplasmic reticulum (ER)-anchored DDEP-inactivated P450 3A is translocated from the ER to the cytosol in a brefeldin A-insensitive manner.
authors.affiliation: Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94143, USA.
authors.forename: H F
authors.initials: HF
authors.lastname: Wang
authors.forename: M E
authors.initials: ME
authors.lastname: Figueiredo Pereira
authors.forename: M A
authors.initials: MA
authors.lastname: Correia
mesh_terms: D015250:Aclarubicin / Q000494:pharmacology; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D001692:Biological Transport; D020126:Brefeldin A / Q000494:pharmacology; D002469:Cell Separation; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D003997:Dicarbethoxydihydrocollidine / Q000031:analogs & derivatives / Q000494:pharmacology; D004347:Drug Interactions; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005260:Female; D007976:Leupeptins / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008954:Models, Biological; D010089:Oxidoreductases, N-Demethylating / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000187:drug effects / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex; D011499:Protein Processing, Post-Translational; D051381:Rats; D017207:Rats, Sprague-Dawley; D014452:Ubiquitins / Q000378:metabolism
chemical_list: D007976:Leupeptins; D011480:Protease Inhibitors; D014452:Ubiquitins; C030826:3,5-dicarbethoxy-2,6-dimethyl-4-ethyl-1,4-dihydropyridine; D020126:Brefeldin A; D003997:Dicarbethoxydihydrocollidine; D015250:Aclarubicin; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; D051544:Cytochrome P-450 CYP3A; D010089:Oxidoreductases, N-Demethylating; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde