title: Hypoxia-inducible factor-1 and activator protein-1 modulate the upregulation of CYP3A6 induced by hypoxia.
abstract: 1. Moderate hypoxia in vivo and serum from rabbits subjected to moderate hypoxia (SHYPO) in vitro reduce CYP1A1 and 1A2 p450 isoforms and upregulate CYP3A6. The aim of this project was to investigate the signal transduction pathways implicated in the upregulation of CYP3A6 expression by hypoxia. 2. Hypoxia in vivo and SHYPO in vitro increased the expression of hypoxia-inducible factor-1alpha (HIF-1alpha) and c-jun, as well as CYP3A6. By electrophoresis mobility shift assay, it was shown that HIF-1 and activator protein-1 (AP-1) bind to CYP3A6 oligonucleotide probe after exposure to hypoxia in vivo and SHYPO in vitro. The effects of hypoxia in vivo or SHYPO in vitro were reproduced by CoCl2 and lead acetate, activators of HIF-1 and AP-1, respectively. 2. PD98059, a p42/44 MAPK inhibitor, prevented the increase of CYP3A6 and c-jun, but did not impede the increase of HIF-1alpha and binding to CYP3A6 oligonucleotide probe. Genistein, an inhibitor of protein tyrosine kinases (PTKs), prevented the increase in HIF-1alpha, c-jun and CYP3A6, as well as HIF-1 and AP-1 binding to CYP3A6 oligonucleotide probe. Moreover, hypoxia in vivo induced constitutive androstane receptor (CAR) as well as CAR binding to the CYP3A6 oligonucleotide probe, but not the pregnane X receptor. 4. In conclusion, hypoxia in vivo and SHYPO induce the expression of CYP3A6. The in vitro induction of CYP3A6 by SHYPO is PTK- and p42/44 MAPK-dependent. The present data support the hypothesis that HIF-1 and AP-1 are part of the signalling pathway leading to CYP3A6 induction by hypoxia.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, University of Montréal, PO Box 6128, Stat. Centre-Ville, Montréal, Québec, Canada H3C 3J7.
authors.forename: Caroline
authors.initials: C
authors.lastname: Fradette
authors.forename: Patrick
authors.initials: P
authors.lastname: du Souich
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics / Q000378:metabolism*; D003035:Cobalt / Q000494:pharmacology; D000090702:Constitutive Androstane Receptor; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D019388:Cytochrome P-450 CYP1A2 / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D000860:Hypoxia / Q000503:physiopathology*; D051793:Hypoxia-Inducible Factor 1; D048031:JNK Mitogen-Activated Protein Kinases; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D015345:Oligonucleotide Probes / Q000378:metabolism; D009942:Organometallic Compounds / Q000494:pharmacology; D000077297:Pregnane X Receptor; D011485:Protein Binding; D011817:Rabbits; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D011987:Receptors, Steroid / Q000378:metabolism; D015398:Signal Transduction; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D000090702:Constitutive Androstane Receptor; D004268:DNA-Binding Proteins; D051793:Hypoxia-Inducible Factor 1; D009687:Nuclear Proteins; D015345:Oligonucleotide Probes; D009942:Organometallic Compounds; D000077297:Pregnane X Receptor; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D003035:Cobalt; D001189:Aryl Hydrocarbon Hydroxylases; D019363:Cytochrome P-450 CYP1A1; D019388:Cytochrome P-450 CYP1A2; C100638:cytochrome P-450 CYP3A6 (rabbit); D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; C018021:cobaltous chloride; C008261:lead acetate