The Ahr-locus encodes the structural gene for the AH-receptor (AHR), a ligand activated transcription factor that mediates many of the biological responses of 2,3,7,8-trachlorodibenzo-p-dioxin (TCDD) and related polychlorinated biphenyls (PCBs). One of the directions of our research is to develop new models of the AHR signalling pathway and to use these models to identify the molecular basis of species dependent responses to TCDD (NIEHS R29-ES05703). In this proposal, we describe experiments that represent a new direction for our laboratory that should provide information valuable in characterizing the risks that compounds like TCDD and PCBs pose to the environment. Over the last two years, we have cloned the AHR cDNA and found that it contains a basic-region/helix-loop-helix domain similar to that found in its dimerization partner ARNT. More recently, our mutagenesis studies have provided a functional map of the AHR and have allowed us to localize those domains required for DNA binding, agonist binding, dimerization and transcriptional activation. In addition, we have cloned and characterized the AHR's structural gene, identified many of the 5' regulatory elements that control its expression and mapped its chromosomal location in mice and humans. In this application, we propose to use this new information and the related molecular probes to identify those developmental stages most sensitive to TCDD-toxicity and to construct transgenic mouse lines with mutant and controllable Ahr- and Arnt-loci. One of our highest priorities will be directed towards development of a targeting vector for use in """"""""knocking- out"""""""" the AHR and ARNT in embryonic stem cells (Bs cells). By injecting these recombinant Es cells into blastocysts, we propose to generate transgenic mice which are heterozygous and homozygous for a null mutation at the Ahr- and Amt-loci. We propose that the mouse strains gene rated under this project will prove valuable in the following ways, 1) to determine the phenotype of mice lacking an AHR or ARNT, 2) to identify the effects of TCDD and PCB mixtures that are not mediated by the AHR or ARNT, 3) as prototype strains for subsequent in vivo mutation studies of the Ahr- and Arnt-loci (e.g. humanizing the murine model), and 4) determining the role of altered gene expression in TCDD toxicity.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES006883-05
Application #
2770752
Study Section
Toxicology Subcommittee 2 (TOX)
Project Start
1994-09-01
Project End
2000-08-31
Budget Start
1998-09-01
Budget End
2000-08-31
Support Year
5
Fiscal Year
1998
Total Cost
Indirect Cost
Name
University of Wisconsin Madison
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Nukaya, Manabu; Walisser, Jacqueline A; Moran, Susan M et al. (2010) Aryl hydrocarbon receptor nuclear translocator in hepatocytes is required for aryl hydrocarbon receptor-mediated adaptive and toxic responses in liver. Toxicol Sci 118:554-63
Nukaya, Manabu; Lin, Bernice C; Glover, Edward et al. (2010) The aryl hydrocarbon receptor-interacting protein (AIP) is required for dioxin-induced hepatotoxicity but not for the induction of the Cyp1a1 and Cyp1a2 genes. J Biol Chem 285:35599-605
Lin, Bernice C; Nguyen, Linh P; Walisser, Jacqueline A et al. (2008) A hypomorphic allele of aryl hydrocarbon receptor-associated protein-9 produces a phenocopy of the AHR-null mouse. Mol Pharmacol 74:1367-71
Lin, Bernice C; Sullivan, Ruth; Lee, Youngsook et al. (2007) Deletion of the aryl hydrocarbon receptor-associated protein 9 leads to cardiac malformation and embryonic lethality. J Biol Chem 282:35924-32
Thomae, Tami L; Stevens, Emily A; Liss, Adam L et al. (2006) The teratogenic sensitivity to 2,3,7,8-tetrachlorodibenzo-p-dioxin is modified by a locus on mouse chromosome 3. Mol Pharmacol 69:770-5
Walisser, Jacqueline A; Glover, Edward; Pande, Kalyan et al. (2005) Aryl hydrocarbon receptor-dependent liver development and hepatotoxicity are mediated by different cell types. Proc Natl Acad Sci U S A 102:17858-63
Bunger, Maureen K; Walisser, Jacqueline A; Sullivan, Ruth et al. (2005) Progressive arthropathy in mice with a targeted disruption of the Mop3/Bmal-1 locus. Genesis 41:122-32
Thomae, Tami L; Stevens, Emily A; Bradfield, Christopher A (2005) Transforming growth factor-beta3 restores fusion in palatal shelves exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin. J Biol Chem 280:12742-6
Walisser, Jacqueline A; Bunger, Maureen K; Glover, Edward et al. (2004) Gestational exposure of Ahr and Arnt hypomorphs to dioxin rescues vascular development. Proc Natl Acad Sci U S A 101:16677-82
Lahvis, G P; Lindell, S L; Thomas, R S et al. (2000) Portosystemic shunting and persistent fetal vascular structures in aryl hydrocarbon receptor-deficient mice. Proc Natl Acad Sci U S A 97:10442-7

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