title: A dominant negative zebrafish Ahr2 partially protects developing zebrafish from dioxin toxicity.
abstract: The toxicity by 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) is thought to be caused by activation of the aryl hydrocarbon receptor (AHR). However, our understanding of how AHR activation by TCDD leads to toxic effects is poor. Ideally we would like to manipulate AHR activity in specific tissues and at specific times. One route to this is expressing dominant negative AHRs (dnAHRs). This work describes the construction and characterization of dominant negative forms of the zebrafish Ahr2 in which the C-terminal transactivation domain was either removed, or replaced with the inhibitory domain from the Drosophila engrailed repressor protein. One of these dnAhr2s was selected for expression from the ubiquitously active e2fα promoter in transgenic zebrafish. We found that these transgenic zebrafish expressing dnAhr2 had reduced TCDD induction of the Ahr2 target gene cyp1a, as measured by 7-ethoxyresorufin-O-deethylase activity. Furthermore, the cardiotoxicity produced by TCDD, pericardial edema, heart malformation, and reduced blood flow, were all mitigated in the zebrafish expressing the dnAhr2. These results provide in vivo proof-of-principle results demonstrating the effectiveness of dnAHRs in manipulating AHR activity in vivo, and demonstrating that this approach can be a means for blocking TCDD toxicity.
authors.affiliation: Department of Biomolecular Chemistry, University of Wisconsin, Madison, Wisconsin, United States of America.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Lanham
authors.forename: Amy L
authors.initials: AL
authors.lastname: Prasch
authors.forename: Kasia M
authors.initials: KM
authors.lastname: Weina
authors.forename: Richard E
authors.initials: RE
authors.lastname: Peterson
authors.forename: Warren
authors.initials: W
authors.lastname: Heideman
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D015153:Blotting, Western; D019556:COS Cells; D018929:Cell Culture Techniques; D002522:Chlorocebus aethiops; D003326:Coronary Circulation / Q000187:drug effects; D019363:Cytochrome P-450 CYP1A1 / Q000096:biosynthesis; D004790:Enzyme Induction / Q000187:drug effects; D005799:Genes, Dominant / Q000235:genetics*; D050505:Mutant Proteins / Q000378:metabolism; D010496:Pericardium / Q000187:drug effects / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D020011:Protective Agents / Q000378:metabolism*; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics* / Q000378:metabolism; D015203:Reproducibility of Results; D014158:Transcription, Genetic; D015027:Zebrafish / Q000235:genetics* / Q000254:growth & development*; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C474372:AHR2 protein, zebrafish; D050505:Mutant Proteins; D000072317:Polychlorinated Dibenzodioxins; D020011:Protective Agents; D018336:Receptors, Aryl Hydrocarbon; D029961:Zebrafish Proteins; D019363:Cytochrome P-450 CYP1A1