Benzo[g,h,i]perylene Synergistically Transactivates Benzo[a]pyrene-Induced CYP1A1 Gene Expression by Aryl Hydrocarbon Receptor Pathway

2001 ◽  
Vol 170 (1) ◽  
pp. 63-68 ◽  
Author(s):  
Shur-Hueih Cherng ◽  
Pinpin Lin ◽  
Jia-Ling Yang ◽  
Shih-Lan Hsu ◽  
Huei Lee
Keyword(s):  
Gene Expression ◽  
Aryl Hydrocarbon Receptor ◽  
Aryl Hydrocarbon ◽  
Cyp1a1 Gene

scholarly journals Disruption of endogenous regulator homeostasis underlies the mechanism of rat CYP1A1 mRNA induction by metyrapone

1998 ◽  
Vol 331 (1) ◽  
pp. 273-281 ◽  
Author(s):  
Joanna L. HARVEY ◽  
Alan J. PAINE ◽  
Matthew C. WRIGHT
Keyword(s):  
Gene Expression ◽  
Glucocorticoid Receptor ◽  
Aryl Hydrocarbon Receptor ◽  
Culture Medium ◽  
Male Rats ◽  
Aryl Hydrocarbon ◽  
Mrna Induction ◽  
Cyp1a1 Gene ◽  
Cyp1a1 Mrna

The transcriptional induction of the cytochrome P-450 1A1 (CYP1A1) gene by xenobiotics such as polyaromatic hydrocarbons is dependent on their interaction with the aryl hydrocarbon receptor. Administration of the structurally unrelated compounds metyrapone (a cytochrome P-450 inhibitor) or dexamethasone (a glucocorticoid) to male rats does not induce hepatic CYP1A1 mRNA. However, administration of both metyrapone and dexamethasone to male rats results in the induction of hepatic CYP1A1 mRNA expression. The induction response is mimicked in vitro in cultured rat hepatocytes by the addition of metyrapone and dexamethasone to a serum-free culture medium, suggesting that these compounds act directly on the liver in vivo to effect hepatic CYP1A1 mRNA induction. An examination of the characteristics of CYP1A1 induction by metyrapone and dexamethasone in combination in vitro indicate that at least 6 h of treatment is required for detectable levels of CYP1A1 mRNA to accumulate in hepatocytes. In contrast, β-naphthoflavone, which is known to bind to the aryl hydrocarbon receptor to effect CYP1A1 gene expression, induces detectable levels of CYP1A1 mRNA within 2 h of treatment. CYP1A1 mRNA is also induced when hepatocytes are treated with metyrapone in combination with the protein synthesis inhibitor cycloheximide but not with dexamethasone in combination with cycloheximide, indicating that CYP1A1 mRNA induction is strictly dependent on the presence of metyrapone and suggesting that the metyrapone-associated induction of CYP1A1 mRNA is dependent on a loss of a constitutively expressed protein that functions to suppress CYP1A1 gene expression. The role of dexamethasone in metyrapone-associated induction of CYP1A1 is probably mediated through the glucocorticoid receptor since the glucocorticoid receptor antagonist RU486 reduces the levels of CYP1A1 mRNA induced by metyrapone and dexamethasone in combination. Increasing the levels of the photosensitizer riboflavin present in the culture medium 10-fold and exposure to light increases the levels of CYP1A1 mRNA induced by metyrapone and dexamethasone in combination in vitro, suggesting that photoactivation of inducing medium constituent(s) might be required for induction. Failure to induce CYP1A1 mRNA by co-administration of metyrapone and dexamethasone in hepatocytes cultured in a balanced salt solution with or without photoactivation indicates that induction is dependent on a photoactivated component of the culture medium and not on metyrapone or dexamethasone alone. The addition of tryptophan in the presence of riboflavin to the balanced salt solution restores CYP1A1 mRNA induction by metyrapone alone and induction is increased when medium is exposed to light, indicating that induction is dependent on tryptophan photoactivation in vitro. Metyrapone failed to compete with 2,3,7,8-tetrachlorodibenzo-p-dioxin for specific binding to the aryl hydrocarbon receptor in rat liver cytosolic fractions. These results suggest that CYP1A1 might be induced in rats by metyrapone through an indirect mechanism associated with an elevation in the level of an endogenously generated inducer such as photoactivated product(s) of tryptophan and not because of metyrapone's interacting with the aryl hydrocarbon receptor. The dependence of CYP1A1 induction on dexamethasone or cycloheximide suggests that derepression by a glucocorticoid receptor-modulated negative-acting factor of CYP1A1 gene expression might be critical to induction by metyrapone.

Modulation of CYP1B1 and CYP1A1 gene expression and activation of aryl hydrocarbon receptor by Ginkgo biloba extract in MCF-10A human mammary epithelial cells

2009 ◽  
Vol 87 (9) ◽  
pp. 674-683 ◽  
Author(s):  
Ganesh Rajaraman ◽  
Guixiang Yang ◽  
Jie Chen ◽  
Thomas K.H. Chang
Keyword(s):  
Gene Expression ◽  
Epithelial Cells ◽  
Aryl Hydrocarbon Receptor ◽  
Ginkgo Biloba ◽  
Mammary Epithelial Cells ◽  
Ginkgo Biloba Extract ◽  
Mammary Epithelial ◽  
Aryl Hydrocarbon ◽  
Cyp1a1 Gene ◽  
Human Mammary Epithelial

The aryl hydrocarbon receptor (AhR) signaling pathway regulates the production of CYP1B1 and CYP1A1, which catalyze the bioactivation of various procarcinogens. In the present study, we investigated the effect of Ginkgo biloba extract and some of its chemical constituents on CYP1B1 and CYP1A1 gene expression and AhR activity in cultured MCF-10A human mammary epithelial cells. Treatment of MCF-10A cells with noncytotoxic concentrations of G. biloba extract (25–300 µg/mL for 24 or 48 h) increased CYP1B1 and CYP1A1 mRNA expression, which was accompanied by an increase in CYP1-mediated ethoxyresorufin O-dealkylation activity. The inductive effects of G. biloba extract were attenuated by an AhR antagonist (3′,4′-dimethoxyflavone). G. biloba extract (25–300 µg/mL) increased AhR-dependent reporter activity, as determined in MCF-10A cells transfected with an AhR-regulated luciferase reporter plasmid (pGudluc6.1). Bilobalide and ginkgolides A, B, C, and J were not responsible for the modulation of CYP1B1 and CYP1A1 gene expression or AhR activation by G. biloba extract. In contrast, quercetin increased CYP1B1 and CYP1A1 gene expression and activated AhR, whereas kaempferol and isorhamnetin suppressed constitutive CYP1B1 expression and antagonized AhR activation by benzo[a]pyrene. Overall, our findings provide an impetus for future investigations on the effect of G. biloba extract in CYP1-mediated chemical carcinogenesis.

scholarly journals Neuronal activity enhances aryl hydrocarbon receptor-mediated gene expression and dioxin neurotoxicity in cortical neurons

2008 ◽  
Vol 104 (5) ◽  
pp. 1415-1429 ◽  
Author(s):  
Chun-Hua Lin ◽  
Shu-Hui Juan ◽  
Chen Yu Wang ◽  
Yu-Yo Sun ◽  
Chih-Ming Chou ◽  
...  
Keyword(s):  
Gene Expression ◽  
Aryl Hydrocarbon Receptor ◽  
Neuronal Activity ◽  
Cortical Neurons ◽  
Aryl Hydrocarbon

scholarly journals Nascent RNA sequencing defines dynamic aryl hydrocarbon receptor signaling responses to wood smoke particles

2021 ◽  
Author(s):  
Arnav Gupta ◽  
Sarah K. Sasse ◽  
Lynn Sanford ◽  
Margaret A. Gruca ◽  
Robin D. Dowell ◽  
...  
Keyword(s):  
Gene Expression ◽  
Aryl Hydrocarbon Receptor ◽  
Airway Epithelial Cells ◽  
Wood Smoke ◽  
Primary Role ◽  
Airway Epithelial ◽  
Transcriptional Responses ◽  
Wildfire Smoke ◽  
Smoke Particles ◽  
Aryl Hydrocarbon

AbstractTranscriptional responses to wildfire smoke, an increasingly important cause of human morbidity, are poorly understood. Here, using a combination of precision nuclear run-on sequencing (PRO-seq) and the assay for transposase-accessible chromatin using sequencing (ATAC-seq), we identify rapid and dynamic changes in transcription and chromatin structure in Beas-2B airway epithelial cells after exposure to wood smoke particles (WSP). By comparing 30 and 120 minutes of WSP exposure, we defined three distinct temporal patterns of transcriptional induction and chromatin responses to WSP. Whereas transcription of canonical targets of the aryl hydrocarbon receptor (AHR), such as CYP1A1 and AHRR, was robustly increased after 30 minutes of WSP exposure, transcription of these genes and associated enhancers returned to near baseline at 120 minutes. ChIP-qPCR assays and AHR knockdown confirmed a role for AHR in regulating these transcriptional responses, and we applied bioinformatics approaches to identify novel AHR-regulated pathways and targets including the DNA methyltransferase, DNMT3L, and its interacting factor, SPOCD1. Our analysis also defined a role for NFkB as a primary transcriptional effector of WSP-induced changes in gene expression. The kinetics of AHR- and NFkB-regulated responses to WSP were distinguishable based on the timing of both transcriptional responses and chromatin remodeling, with induction of several cytokines implicated in maintaining the NFkB response. In aggregate, our data establish a direct and primary role for AHR in mediating airway epithelial responses to WSP and identify crosstalk between AHR and NFkB signaling in controlling pro-inflammatory gene expression.

Involvement of aryl hydrocarbon receptor nuclear translocator in EGF-induced c-Jun/Sp1-mediated gene expression

2010 ◽  
Vol 67 (20) ◽  
pp. 3523-3533 ◽  
Author(s):  
Wan-Chen Huang ◽  
Shu-Ting Chen ◽  
Wei-Chiao Chang ◽  
Kwang-Yu Chang ◽  
Wen-Chang Chang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Aryl Hydrocarbon Receptor ◽  
Aryl Hydrocarbon
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