Toxicity of the chemical class of xenobiotics that include polycyclic aromatic hydrocarbons (PAH) and halogenated hydrocarbons, such as polychlorinated biphenyls and dibenzodioxins, most likely occurs through control of gene expression. The molecular mechanism is largely unknown, but is currently believed to involve, In part, a cytosolic receptor, the aryl hydrocarbon or Ah-receptor. If the mechanism responsible for the many toxic effects associated with these classes of chemicals is to be unraveled, it will be necessary to study other genes that may be regulated through additional cellular mediators. This grant proposal focuses on the human cytochrome P4501A2 gene (CYP1A2), a member of the PAH-inducible CYP1A gene family that is prominent in human liver, and metabolizes drugs, such as acetaminophen, caffeine, environmental agents such as arylamines and dietary constituents, such as heterocyclic amines and aflatoxins. The molecular mechanism for the regulation of the human CYP1A2 gene will be studied through the characterization of cis-acting elements and identification of trans-acting factors utilizing transient transfection assays and in vitro DNA binding assays, such as DNase I footprinting. In vivo footprinting studies in human primary hepatocytes will be conducted to examine the temporal relationship among transcription factors in regulating CYP1A2 gene expression. Several model systems will be utilized for the proposed research, including human hepatoma cell lines, human liver and non-proliferating cultures of human hepatocytes. A Cell Culture Core and Human Tissue Bank will provide the necessary support for these studies. It is believed that a combination of these molecular and cell culture approaches will elucidate the mechanism by which this important gene is regulated.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM054477-03
Application #
2546035
Study Section
Toxicology Subcommittee 2 (TOX)
Project Start
1995-09-30
Project End
1999-09-29
Budget Start
1997-09-30
Budget End
1998-09-29
Support Year
3
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Colorado Denver
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
065391526
City
Aurora
State
CO
Country
United States
Zip Code
80045
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Black, Virginia H; Quattrochi, Linda C (2004) Molecular cloning of the guinea pig CYP1A2 gene 5'-flanking region: identification of functional aromatic hydrocarbon response element and characterization of CYP1A2 expression in GPC16 cells. Drug Metab Dispos 32:595-602
Williams, Susanne N; Pickwell, George V; Quattrochi, Linda C (2003) A combination of tea (Camellia senensis) catechins is required for optimal inhibition of induced CYP1A expression by green tea extract. J Agric Food Chem 51:6627-34
Pickwell, George V; Shih, Hsueh; Quattrochi, Linda C (2003) Interaction of upstream stimulatory factor proteins with an E-box located within the human CYP1A2 5'-flanking gene contributes to basal transcriptional gene activation. Biochem Pharmacol 65:1087-96
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Allen, S W; Mueller, L; Williams, S N et al. (2001) The use of a high-volume screening procedure to assess the effects of dietary flavonoids on human cyp1a1 expression. Drug Metab Dispos 29:1074-9
Aitchison, K J; Gonzalez, F J; Quattrochi, L C et al. (2000) Identification of novel polymorphisms in the 5' flanking region of CYP1A2, characterization of interethnic variability, and investigation of their functional significance. Pharmacogenetics 10:695-704
Shih, H; Pickwell, G V; Quattrochi, L C (2000) Differential effects of flavonoid compounds on tumor promoter-induced activation of the human CYP1A2 enhancer. Arch Biochem Biophys 373:287-94

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