DMD Large equally mixed donor pool

Home Help [Feedback] [For Subscribers] [Archive] [Search] --
QUICK SEARCH:   [advanced]


     

Drug Metabolism and Disposition Fast Forward
First published on February 15, 2007; DOI: 10.1124/dmd.106.014423

This Article
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
dmd.106.014423v1
35/5/787    most recent
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Abu-Bakar, A.
Right arrow Articles by Hakkola, J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Abu-Bakar, A.
Right arrow Articles by Hakkola, J.


Received for publication December 20, 2006.
Revised February 8, 2007.
Accepted for publication February 12, 2007.

REGULATION OF CYTOCHROME P450 2A5 GENE BY THE TRANSCRIPTION FACTOR NRF2 (NUCLEAR FACTOR (ERYTHROID- DERIVED 2)-LIKE 2

A'edah Abu-Bakar 1*, Virpi Lamsa 2, Satu Arpiainen 2, Michael R Moore 1, Matti A Lang 3, Jukka Hakkola 2

1 National Research Centre for Environmental Toxicology, University of Queensland, Australia 2 Department of Pharmacology and Toxicology, University of Oulu, Finland 3 Division of Pharmaceutical Biochemistry, Uppsala Biomedical Centre, Uppsala University, Sweden

* Address correspondence to: E-mail: a.abubakar{at}uq.edu.au

Abstract

We have previously shown that cadmium, a metal that alters cellular redox status, induces cytochrome P450 2A5 (CYP2A5) expression in nuclear factor (erythroid-derived 2)-like 2 wildtype (Nrf2 +/+) mice but not in the knockout (Nrf2 -/-) mice. In the present studies, the potential role of Nrf2 in cadmium-mediated regulation of Cyp2a5 gene was investigated in mouse primary hepatocytes. Cadmium chloride (CdCl2) caused a time-dependent induction of the CYP2A5 at mRNA, protein, and activity, levels with a substantial increase observed within 3 h of exposure. Immunoblotting showed cadmium-dependent nuclear accumulation of Nrf2 within 1 h of exposure. Co-transfection of mouse primary hepatocytes with Cyp2a5 promoter-luciferase reporter plasmids and Nrf2 expression plasmid resulted in a 3-fold activation of Cyp2a5 promoter-mediated transcription relative to the control. Deletion analysis of the promoter localised the Nrf2 responsive region to an area from -2656 to -2339 bp. Computer-based sequence analysis identified two putative stress response elements (StREs) within the region at positions -2514 to -2505 and -2386 to -2377. Chromatin immunoprecipitation and electrophoretic mobility shift assays showed that interaction of the more proximal StRE with Nrf2 was stimulated by CdCl2. Finally, site-directed mutagenesis of the proximal StRE in Cyp2a5 promoter-luciferase reporter plasmids abolished Nrf2 mediated induction. Collectively, the results indicate that Nrf2 activates Cyp2a5 transcription by directly binding to the StRE in the 5'-flanking region of the gene. This acknowledges Cyp2a5 as the first phase I xenobiotic-metabolizing gene identified under the control of the StRE-Nrf2 pathway with a potential role in adaptive response to cellular stress.


Key words: CYP expression, CYP gene regulation, CYP2A, heme metabolism, heme oxygenases, hepatocytes, liver microsomes, metal toxicology, oxidative stress




Home Help [Feedback] [For Subscribers] [Archive] [Search] --
All ASPET Journals Molecular Pharmacology Pharmacological Reviews
Molecular Interventions Drug Metabolism and Disposition

Copyright © 2007 by the American Society for Pharmacology and Experimental Therapeutics.