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CYP1A1 regulation by oral exposure to benzo[a]pyrene using a CYP1A1 GFP transgenic mouse model
Author(s) -
Operana Theresa N.,
Nguyen Nghia,
Chen Shujuan,
Beaton Dierdre,
Tukey Robert H
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a263-d
Subject(s) - benzo(a)pyrene , green fluorescent protein , western blot , microbiology and biotechnology , chemistry , transgene , in vivo , genetically modified mouse , microsome , biology , gene , in vitro , biochemistry , carcinogen
The CYP1A1 gene is regulated by the Ah receptor and plays an important role in detoxification as well as bioactivation of compounds such as polycyclic aromatic hydrocarbons (PAHs). Thus, the ability of toxicants and drugs to induce CYP1A1 serves as a biomarker for exposure. In order to examine the regulation of human CYP1A1 in vivo, we created a transgenic mouse expressing a chimeric gene consisting of the entire human CYP1A1 gene (15 kb) fused with a GFP reporter gene (Tg‐ CYP1A1 GFP ). The treatment of Tg‐ CYP1A1 GFP with a single i.p. dose of TCDD led to the induction of CYP1A1‐GFP in both the liver and lung as determined by Western blot analysis using CYP1A1 and GFP specific antibodies. Fluorescence microscopy showed cell‐specific localization of CYP1A1‐GFP restricted to hepatocytes and Clara cells in the liver and lung, respectively. Similar results were observed following an i.p. dose of benzo[a]pyrene (B[a]P). However, oral administration of B[a]P resulted in CYP1A1‐GFP induction in liver without concomitant induction of mouse Cyp1a1 as verified by Western blot analysis. In addition, the level of EROD activity was increased in liver microsomes from oral B[a]P treated Tg‐ CYP1A1 GFP compared to B[a]P treated wild type mice, indicating that induced CYP1A1‐GFP is functional and fully active in the liver. No differences in induction of mouse or human CYP1A1 were observed in the lung after oral B[a]P treatment. These data suggest organ‐specific sensitivity to oral B[a]P exposure. (Supported by USPHS grant ES10337)