The Human CYP1A1 Gene Is Regulated in a Developmental and Tissue-specific Fashion in Transgenic Mice

Galijatovic, Alema; Beaton, Deirdre; Nguyen, Nghia; Chen, Shujuan; Bonzo, Jessica A.; Johnson, Randall S.; Maeda, Shin; Karin, Michael; Guengerich, F. Peter; Tukey, Robert H.

doi:10.1074/jbc.m400973200

Cited by 23 publications

(17 citation statements)

References 36 publications

(24 reference statements)

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“…It has been reported that two DREs (mouse DRE4 and DRE7) are fully conserved in the position and sequence with the cluster of human DREs, and both of them show AhR binding activity in vitro [29]. In addition, the regulatory regions flanking the human and mouse dioxin-responsive receptor-enhancer regions may contribute significantly toward differences in expression patterns, as determined by induction [30]. …”

Section: Resultsmentioning

confidence: 99%

Functional Analysis of the Dioxin Response Elements (DREs) of the Murine CYP1A1 Gene Promoter: Beyond the Core DRE Sequence

Pei

Zhang

et al. 2014

IJMS

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The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that mediates the biological and toxicological effects of halogenated aromatic hydrocarbons, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). When activated by dioxin, the cytosolic AhR protein complex translocates into the nucleus and dimerizes with the ARNT (Ah receptor nuclear translocator) protein. The heteromeric ligand:AhR/Arnt complex then recognizes and binds to its specific DNA recognition site, the dioxin response element (DRE). DREs are located upstream of cytochrome P4501A1 (CYP1A1) and other AhR-responsive genes, and binding of the AhR complex stimulates their transcription. Although CYP1A1 expression has been used as the model system to define the biochemical and molecular mechanism of AhR action, there is still limited knowledge about the roles of each of the seven DREs located in the CYP1A1 promoter. These seven DREs are conserved in mouse, human and rat. Deletion analysis showed that a single DRE at −488 was enough to activate the transcription. Truncation analysis demonstrated that the DRE at site −981 has the highest transcriptional efficiency in response to TCDD. This result was verified by mutation analysis, suggesting that the conserved DRE at site −981 could represent a significant and universal AhR regulatory element for CYP1A1. The reversed substituted intolerant core sequence (5′-GCGTG-3′ or 5′-CACGC-3′) of seven DREs reduced the transcriptional efficiency, which illustrated that the adjacent sequences of DRE played a vital role in activating transcription. The core DRE sequence (5′-TNGCGTG-3′) tends to show a higher transcriptional level than that of the core DRE sequence (5′-CACGCNA-3′) triggered by TCDD. Furthermore, in the core DRE (5′-TNGCGTG-3′) sequence, when “N” is thymine or cytosine (T or C), the transcription efficiency was stronger compared with that of the other nucleotides. The effects of DRE orientation, DRE adjacent sequences and the nucleotide “N” in the core DRE (5′-TNGCGTG-3′) sequence on the AhR-regulated CYP1A1 transcription in response to TCDD were studied systematically, and our study laid a good foundation for further investigation into the AhR-dependent transcriptional regulation triggered by dioxin and dioxin-like compounds.

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Section: Resultsmentioning

confidence: 99%

Functional Analysis of the Dioxin Response Elements (DREs) of the Murine CYP1A1 Gene Promoter: Beyond the Core DRE Sequence

Pei

Zhang

et al. 2014

IJMS

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“…The molecular mechanisms by which MC or TCDD transcriptionally activate the CYP1A1 gene entail the binding of the ligand to the Ah-receptor (AHR), a cytosolic protein. The ligand-bound AHR complex translocates into the nucleus, where it dimerizes with the Ah receptor nuclear translocator (ARNT), and this heterodimer binds to aryl hydrocarbon responsive elements (AHREs), which are located in enhancer regions of CYP1A1, resulting in augmented expression of the CYP1A1 gene [12–16]. …”

Section: Introductionmentioning

confidence: 99%

Persistent induction of cytochrome P450 (CYP)1A enzymes by 3-methylcholanthrene in vivo in mice is mediated by sustained transcriptional activation of the corresponding promoters

Jiang

Wang

Zhang³

et al. 2009

Biochemical and Biophysical Research Communications

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There is significant human exposure to polycyclic aromatic hydrocarbons (PAHs), many of which are potent carcinogens. Cytochrome P450 (CYP)1A enzymes play key roles in the metabolic activation of PAHs to carcinogenic metabolites. We previously showed persistent induction of CYP1A enzymes by 3-methylcholanthrene (MC) in vivo in rodents. In this study, we tested the hypothesis that MC elicits persistent induction of CYP1A1 and 1A2 in vivo by mechanisms entailing sustained transcriptional activation of the corresponding promoters. Adult male wild type (WT) (Cd-1) mice, transgenic mice expressing the human CYP1A1 promoter or the mouse CYP1A2 promoter were treated with the vehicle corn oil (CO) or the carcinogenic PAH, 3-methylcholanthrene (MC), once daily for 4 days, and luciferase reporter gene expression was determined at 1, 8. 15, and 22 days after MC withdrawal by bioluminescent imaging. Pulmonary and hepatic endogenous expression of CYP1A1 and 1A2 was also determined at the enzymatic, protein, and mRNA levels. The major findings were that MC elicited marked enhancement in the luciferase expression in the CYP1A1-luc as well CYP1A2-luc transgenic mice that was sustained for up to 22 days, the magnitude of induction being more pronounced in the CYP1A1-luc mice. MC also caused persistent induction of endogenous CYP1A1 and 1A2 expression in the WT, CYP1A1-luc, and 1A2-luc mice for up to 22 days. In conclusion, our results support the hypothesis that MC elicits sustained CYP1A1 and 1A2 expression by sustained transcriptional activation of the corresponding promoters. Thus, these novel transgenic models should be very useful for further understanding of the molecular mechanisms of persistent CYP1A induction, in relation to PAH-mediated carcinogenesis.

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“…Transgenic animal models expressing human P450 genes were previously described that have been used to investigate the contribution of regulatory factors that control gene expression in vivo (Corchero et al, 2001;Granvil et al, 2003;Galijatovic et al, 2004). Such transgenic mouse models provide valuable tools for predicting drug metabolism, disposition, and drug-drug interactions of chemicals that are human CYP2E1 substrates.…”

Section: Human Cyp2e1 Expression In Transgenic Micementioning

confidence: 99%

THECYP2E1-HUMANIZED TRANSGENIC MOUSE: ROLE OF CYP2E1 IN ACETAMINOPHEN HEPATOTOXICITY

et al. 2004

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ABSTRACT:The cytochrome P450 (P450) CYP2E1 enzyme metabolizes and activates a wide array of toxicological substrates, including alcohols, the widely used analgesic acetaminophen, acetone, benzene, halothane, and carcinogens such as azoxymethane and dimethylhydrazine. Most studies on the biochemical and pharmacological actions of CYP2E1 are derived from studies with rodents, rabbits, and cultured hepatocytes; therefore, extrapolation of the results to humans can be difficult. Creating "humanized" mice by introducing the human CYP2E1 gene into Cyp2e1-null mice can circumvent this disadvantage. A transgenic mouse line expressing the human CYP2E1 gene was established. Western blot and high-performance liquid chromatography/mass spectrometry analyses revealed human CYP2E1 protein expression and enzymatic activity in the liver of CYP2E1-humanized mice. Treatment of mice with the CYP2E1 inducer acetone demonstrated that human CYP2E1 was inducible in this transgenic model. The response to the CYP2E1 substrate acetaminophen was explored in the CYP2E1-humanized mice. Hepatotoxicity, resulting from the CYP2E1-mediated activation of acetaminophen, was demonstrated in the livers of CYP2E1-humanized mice by elevated serum alanine aminotransferase levels, increased hepatocyte necrosis, and decreased P450 levels. These data establish that in this humanized mouse model, human CYP2E1 is functional and can metabolize and activate different CYP2E1 substrates such as chlorzoxazone, p-nitrophenol, acetaminophen, and acetone. CYP2E1-humanized mice will be of great value for delineating the role of human CYP2E1 in ethanol-induced oxidative stress and alcoholic liver damage. They will also function as an important in vivo tool for predicting drug metabolism and disposition and drug-drug interactions of chemicals that are substrates for human CYP2E1.The cytochrome P450 (P450) family of enzymes play an important role in the metabolic activation of chemicals to cytotoxic or carcinogenic products, as well as the oxidation of therapeutically used drugs and endogenous steroids (Guengerich et al., 1991;Lieber, 1997). In particular, CYP2E1 is of interest since it metabolizes and activates a wide array of toxicologically important substrates, including acetaminophen (APAP), acetone, benzene, halothane, ethanol, carbon tetrachloride, and carcinogens such as the low molecular weight nitrosamines (Kessova and Cederbaum, 2003). CYP2E1 metabolizes a small number of clinically employed drugs such as disulfiram and the muscle relaxant chlorzoxazone, which undergoes 6-hydroxylation (Peter et al., 1990;Carriere et al., 1993). CYP2E1 also oxidizes a significant number of important occupational and industrial chemicals, including alkanes, alkenes, solvents, and aromatic and halogenated hydrocarbons (Bolt et al., 2003).APAP is a widely used analgesic and is considered safe at therapeutic doses; hepatotoxicity occurs at low frequency. Metabolism of APAP was shown to be primarily contributed by CYP2E1 (Raucy et al., 1989;Snawder et al., 1994a;Kostrubsky et al...

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The Human CYP1A1 Gene Is Regulated in a Developmental and Tissue-specific Fashion in Transgenic Mice

Cited by 23 publications

References 36 publications

Functional Analysis of the Dioxin Response Elements (DREs) of the Murine CYP1A1 Gene Promoter: Beyond the Core DRE Sequence

Functional Analysis of the Dioxin Response Elements (DREs) of the Murine CYP1A1 Gene Promoter: Beyond the Core DRE Sequence

Persistent induction of cytochrome P450 (CYP)1A enzymes by 3-methylcholanthrene in vivo in mice is mediated by sustained transcriptional activation of the corresponding promoters

THECYP2E1-HUMANIZED TRANSGENIC MOUSE: ROLE OF CYP2E1 IN ACETAMINOPHEN HEPATOTOXICITY

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