The stated long-term objective of the research is to understand the molecular mechanism by which the widespread environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) elicits its adaptive and adverse biological effects. In experimental animals, TCDD induces the activities of xenobiotic-metabolizing enzymes, an adaptive response to a change in the cell' chemical environment. TCDD also produces adverse effects such as cancer, reproductive abnormalities, and immunotoxicity in animals. In humans, TCDD produces adaptive and adverse effects (enzyme induction, chloracne); however, the risk that TCDD poses to public health is a matter of current debate. Mechanistic knowledge of TCDD action should permit better understanding of its potential adverse health effects and provide a biological basis for models use to assess its risk. The experiments described here utilize biochemical, genetic, and molecular biological techniques to analyze the mechanism of TCDD action in mouse hepatoma cells in culture. The project involves (i) analysis o a domain of the aromatic hydrocarbon receptor (AhR) that inhibits its trans-activation capability, (ii) studies of a cytoplasmic AhR-interacting protein, and (iii) analysis of the mechanism by which TCDD induces ecto-ATPase gene expression. The experiments address issues related to non-genotoxic environmental contaminants, molecular toxicology, dioxin biology, the regulation of mammalian gene expression, AhR and related transcription factors adaptive responses to xenobiotics, and the maintenance of cellular homeostasis in the face of environmental changes.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES003719-16
Application #
6178263
Study Section
Chemical Pathology Study Section (CPA)
Program Officer
Heindel, Jerrold
Project Start
1985-06-15
Project End
2002-05-31
Budget Start
2000-06-01
Budget End
2001-05-31
Support Year
16
Fiscal Year
2000
Total Cost
$253,975
Indirect Cost
Name
Stanford University
Department
Biology
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

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