Cytochrome P450 3A degradation in isolated rat hepatocytes: 26S proteasome inhibitors as probes

Arch Biochem Biophys. 1999 May 1;365(1):45-53. doi: 10.1006/abbi.1999.1139.

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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aclarubicin / pharmacology
  • Animals
  • Aryl Hydrocarbon Hydroxylases*
  • Biological Transport
  • Brefeldin A / pharmacology
  • Cell Separation
  • Cytochrome P-450 CYP3A
  • Cytochrome P-450 Enzyme System / metabolism*
  • Cytosol / metabolism
  • Dicarbethoxydihydrocollidine / analogs & derivatives
  • Dicarbethoxydihydrocollidine / pharmacology
  • Drug Interactions
  • Endoplasmic Reticulum / metabolism
  • Female
  • Leupeptins / pharmacology
  • Liver / cytology
  • Liver / drug effects
  • Liver / metabolism*
  • Models, Biological
  • Oxidoreductases, N-Demethylating / metabolism*
  • Peptide Hydrolases / drug effects
  • Peptide Hydrolases / metabolism*
  • Protease Inhibitors / pharmacology*
  • Proteasome Endopeptidase Complex*
  • Protein Processing, Post-Translational
  • Rats
  • Rats, Sprague-Dawley
  • Ubiquitins / metabolism

Substances

  • Leupeptins
  • Protease Inhibitors
  • Ubiquitins
  • 3,5-dicarbethoxy-2,6-dimethyl-4-ethyl-1,4-dihydropyridine
  • Brefeldin A
  • Dicarbethoxydihydrocollidine
  • Aclarubicin
  • Cytochrome P-450 Enzyme System
  • Aryl Hydrocarbon Hydroxylases
  • Cytochrome P-450 CYP3A
  • Oxidoreductases, N-Demethylating
  • Peptide Hydrolases
  • Proteasome Endopeptidase Complex
  • ATP dependent 26S protease
  • benzyloxycarbonylleucyl-leucyl-leucine aldehyde