DMD Simcyp

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


     

Drug Metabolism and Disposition Fast Forward
First published on June 4, 2008; DOI: 10.1124/dmd.108.020966

This Article
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
dmd.108.020966v1
36/9/1803    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 Sawaya, R. M.
Right arrow Articles by Riddick, D. S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Sawaya, R. M.
Right arrow Articles by Riddick, D. S.


Received for publication February 14, 2008.
Revised May 16, 2008.
Accepted for publication June 3, 2008.

Cytochrome P450 2C11 5'-flanking region and promoter mediate in vivo suppression by 3-methylcholanthrene

Rana M. Sawaya 1 David S. Riddick 1*

1 University of Toronto

* Address correspondence to: E-mail: david.riddick{at}utoronto.ca

Abstract

Aromatic hydrocarbons such as 3-methylcholanthrene (MC) elicit toxic and adaptive responses through the aryl hydrocarbon receptor (AHR). Aromatic hydrocarbons act via an unknown mechanism to suppress the transcription of CYP2C11, a growth hormone-regulated gene encoding the male-specific rat hepatic cytochrome P450 2C11. We hypothesize that suppression of CYP2C11 by aromatic hydrocarbons is mediated by the gene's promoter and 5'-flank. Using hydrodynamics-based injections to deliver plasmid DNA to the liver of live rats, we studied the MC-responsiveness of luciferase constructs containing 10.1-kb, 5.6-kb and 2.4-kb of the CYP2C11 5'-flank. MC suppressed CYP2C11-luciferase activity of the 10.1-kb and 5.6-kb constructs to below 50% of vehicle levels by 24 h and 72 h. Luciferase activity of the 2.4-kb CYP2C11 construct was decreased to 63% of vehicle levels 24 h after MC treatment, but no suppression was detected by 72h. Negative regulatory element(s) responsible for CYP2C11 reporter suppression by MC exist in the proximal 2.4-kb of the 5'-flank; however, additional cis-acting elements located between -5.6-kb and -2.4-kb mediate persistent reporter suppression. As a positive control for AHR activation, MC dramatically induced the luciferase activity of a Cyp1a1-driven luciferase plasmid under AHR control. Modulation of reporter gene activity by MC was accompanied by induction of endogenous CYP1A1 and suppression of endogenous CYP2C11 mRNA/protein. This is the first demonstration of aromatic hydrocarbon-mediated suppression of a CYP2C11-luciferase construct and this finding suggests that the 5'-flanking region and promoter mediate down-regulation of this gene in the intact rat.


Key words: Ah receptor, CYP gene regulation, CYP2C, cytochrome P450 regulation, polycyclic aromatic hydrocarbons, toxicology, transcriptional regulation




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

Copyright © 2008 by the American Society for Pharmacology and Experimental Therapeutics.