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.
Copyright 1999 Academic Press.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Aclarubicin / pharmacology
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Animals
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Aryl Hydrocarbon Hydroxylases*
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Biological Transport
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Brefeldin A / pharmacology
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Cell Separation
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Cytochrome P-450 CYP3A
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Cytochrome P-450 Enzyme System / metabolism*
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Cytosol / metabolism
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Dicarbethoxydihydrocollidine / analogs & derivatives
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Dicarbethoxydihydrocollidine / pharmacology
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Drug Interactions
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Endoplasmic Reticulum / metabolism
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Female
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Leupeptins / pharmacology
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Liver / cytology
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Liver / drug effects
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Liver / metabolism*
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Models, Biological
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Oxidoreductases, N-Demethylating / metabolism*
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Peptide Hydrolases / drug effects
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Peptide Hydrolases / metabolism*
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Protease Inhibitors / pharmacology*
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Proteasome Endopeptidase Complex*
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Protein Processing, Post-Translational
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Rats
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Rats, Sprague-Dawley
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Ubiquitins / metabolism
Substances
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Leupeptins
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Protease Inhibitors
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Ubiquitins
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3,5-dicarbethoxy-2,6-dimethyl-4-ethyl-1,4-dihydropyridine
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Brefeldin A
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Dicarbethoxydihydrocollidine
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Aclarubicin
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Cytochrome P-450 Enzyme System
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Aryl Hydrocarbon Hydroxylases
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Cytochrome P-450 CYP3A
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Oxidoreductases, N-Demethylating
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Peptide Hydrolases
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Proteasome Endopeptidase Complex
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ATP dependent 26S protease
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benzyloxycarbonylleucyl-leucyl-leucine aldehyde