TitleAHR2 mutant reveals functional diversity of aryl hydrocarbon receptors in zebrafish.
Publication TypeJournal Article
Year of Publication2012
AuthorsGoodale, BC, La Du, JK, Bisson, WH, Janszen, DB, Waters, KM, Tanguay, RL
JournalPLoS One
Volume7
Issue1
Paginatione29346
Date Published2012
ISSN1932-6203
KeywordsAmino Acid Sequence, Animals, Aryl Hydrocarbon Hydroxylases, Base Sequence, Bone and Bones, Embryo, Nonmammalian, Gene Expression Regulation, Developmental, Isoxazoles, Leflunomide, Ligands, Models, Molecular, Molecular Sequence Data, Mutation, Polychlorinated Dibenzodioxins, Protein Isoforms, Receptors, Aryl Hydrocarbon, RNA, Messenger, Skin, Thermodynamics, Zebrafish, Zebrafish Proteins
Abstract

The aryl hydrocarbon receptor (AHR) is well known for mediating the toxic effects of TCDD and has been a subject of intense research for over 30 years. Current investigations continue to uncover its endogenous and regulatory roles in a wide variety of cellular and molecular signaling processes. A zebrafish line with a mutation in ahr2 (ahr2(hu3335)), encoding the AHR paralogue responsible for mediating TCDD toxicity in zebrafish, was developed via Targeting Induced Local Lesions IN Genomes (TILLING) and predicted to express a non-functional AHR2 protein. We characterized AHR activity in the mutant line using TCDD and leflunomide as toxicological probes to investigate function, ligand binding and CYP1A induction patterns of paralogues AHR2, AHR1A and AHR1B. By evaluating TCDD-induced developmental toxicity, mRNA expression changes and CYP1A protein in the AHR2 mutant line, we determined that ahr2(hu3335) zebrafish are functionally null. In silico modeling predicted differential binding of TCDD and leflunomide to the AHR paralogues. AHR1A is considered a non-functional pseudogene as it does not bind TCCD or mediate in vivo TCDD toxicity. Homology modeling, however, predicted a ligand binding conformation of AHR1A with leflunomide. AHR1A-dependent CYP1A immunohistochemical expression in the liver provided in vivo confirmation of the in silico docking studies. The ahr2(hu3335) functional knockout line expands the experimental power of zebrafish to unravel the role of the AHR during development, as well as highlights potential activity of the other AHR paralogues in ligand-specific toxicological responses.

DOI10.1371/journal.pone.0029346
Alternate JournalPLoS ONE
PubMed ID22242167
PubMed Central IDPMC3252317
Grant List3 P42 ES016465 / ES / NIEHS NIH HHS / United States
32ES7060 / ES / NIEHS NIH HHS / United States
ES00210 / ES / NIEHS NIH HHS / United States
P42 ES016465 / ES / NIEHS NIH HHS / United States
T32 ES007060 / ES / NIEHS NIH HHS / United States
P30 ES000210 / ES / NIEHS NIH HHS / United States