The long-term goal of this project is to understand the molecular mechanism of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) action. TCDD is a widespread, persistent environmental contaminant that, in animals, produces morphological, immunologic, biochemical, teratogenic, and neoplastic effects. The risk that TCDD poses to humans is unknown, with potential reproductive and carcinogenic effects being of most concern. The induction of CYP1A1 gene transcription in mouse hepatoma cells constitutes a useful model response for analyzing the mechanism of dioxin action. The increase in gene expression requires the binding of TCDD to an intracellular protein (the Ah receptor), followed by the binding of the liganded receptor to a transcriptional enhancer, situated upstream of the target CYP1A1 gene. The experiments proposed here are designed to analyze the receptor-enhancer mechanism in greater depth. The studies involve the use of molecular biological techniques to (a) analyze the structure and function of the dioxin-responsive enhancer, (b) purify the Ah receptor protein and identify its cDNA, and (c) analyze the TCDD-inducible, Ah receptor-dependent protein-DNA interactions at the dioxin-responsive enhancer within the intact cell.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
2R01ES003719-06
Application #
3251287
Study Section
Metabolic Pathology Study Section (MEP)
Project Start
1985-06-15
Project End
1995-05-31
Budget Start
1990-06-01
Budget End
1991-05-31
Support Year
6
Fiscal Year
1990
Total Cost
Indirect Cost
Name
Stanford University
Department
Type
Schools of Medicine
DUNS #
800771545
City
Stanford
State
CA
Country
United States
Zip Code
94305
Gao, L; Whitlock Jr, J P (2001) Accessibility and activity of the promoter for a dioxin-inducible ecto-ATPase gene. Arch Biochem Biophys 392:270-8
Okino, S T; Whitlock Jr, J P (2000) The aromatic hydrocarbon receptor, transcription, and endocrine aspects of dioxin action. Vitam Horm 59:241-64
Whitlock Jr, J P (1999) Induction of cytochrome P4501A1. Annu Rev Pharmacol Toxicol 39:103-25
Gao, L; Dong, L; Whitlock Jr, J P (1998) A novel response to dioxin. Induction of ecto-ATPase gene expression. J Biol Chem 273:15358-65
Whitlock Jr, J P; Chichester, C H; Bedgood, R M et al. (1997) Induction of drug-metabolizing enzymes by dioxin. Drug Metab Rev 29:1107-27
Ma, Q; Whitlock Jr, J P (1997) A novel cytoplasmic protein that interacts with the Ah receptor, contains tetratricopeptide repeat motifs, and augments the transcriptional response to 2,3,7,8-tetrachlorodibenzo-p-dioxin. J Biol Chem 272:8878-84
Whitlock Jr, J P; Okino, S T; Dong, L et al. (1996) Cytochromes P450 5: induction of cytochrome P4501A1: a model for analyzing mammalian gene transcription. FASEB J 10:809-18
Ma, Q; Whitlock Jr, J P (1996) The aromatic hydrocarbon receptor modulates the Hepa 1c1c7 cell cycle and differentiated state independently of dioxin. Mol Cell Biol 16:2144-50
Dong, L; Ma, Q; Whitlock Jr, J P (1996) DNA binding by the heterodimeric Ah receptor. Relationship to dioxin-induced CYP1A1 transcription in vivo. J Biol Chem 271:7942-8
Ma, Q; Dong, L; Whitlock Jr, J P (1995) Transcriptional activation by the mouse Ah receptor. Interplay between multiple stimulatory and inhibitory functions. J Biol Chem 270:12697-703

Showing the most recent 10 out of 25 publications