title: Molecular cloning and characterization of the aryl hydrocarbon receptors and aryl hydrocarbon receptor nuclear translocators in the American alligator.
abstract: Aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, binds to a variety of chemical compounds including various environmental contaminants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin. This receptor regulates expression of target genes through dimerization with the AHR nuclear translocator (ARNT). Since AHR-ARNT signaling pathways differ among species, characterization of AHR and ARNT is important to assess the effects of environmental contamination and for understanding the molecular mechanism underlying the intrinsic function. In this study, we isolated the cDNAs encoding three types of AHR and two types of ARNT from a reptile, the American alligator (Alligator mississippiensis). In vitro reporter gene assays showed that all complexes of alligator AHR-ARNT were able to activate ligand-dependent transcription on a xenobiotic response element. We found that AHR-ARNT complexes had higher sensitivities to a ligand than AHR-ARNT2 complexes. Alligator AHR1B showed the highest sensitivity in transcriptional activation induced by indigo when compared with AHR1A and AHR2. Taken together, our data revealed that all three alligator AHRs and two ARNTs were functional in the AHR signaling pathway with ligand-dependent and isoform-specific transactivations in vitro.
authors.affiliation: Graduate School of Life Science and Department of Biological Sciences, Hokkaido University, Sapporo, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Oka
authors.affiliation: Department of Obstetrics and Gynecology, and Marine Biomedicine and Environmental Science Center, Medical University of South Carolina, and Hollings Marine Laboratory, Charleston, SC, USA.
authors.forename: Satomi
authors.initials: S
authors.lastname: Kohno
authors.affiliation: Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, Koyama, Tottori, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Ohta
authors.affiliation: Department of Obstetrics and Gynecology, and Marine Biomedicine and Environmental Science Center, Medical University of South Carolina, and Hollings Marine Laboratory, Charleston, SC, USA.
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Guillette
authors.affiliation: Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, and Department of Basic Biology, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi, Japan.
authors.forename: Taisen
authors.initials: T
authors.lastname: Iguchi
authors.affiliation: Graduate School of Life Science and Department of Biological Sciences, Hokkaido University, Sapporo, Japan. Electronic address: ykatsu@sci.hokudai.ac.jp.
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Katsu
mesh_terms: D000489:Alligators and Crocodiles / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator / Q000737:chemistry / Q000235:genetics*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D020869:Gene Expression Profiling; D006801:Humans; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000737:chemistry / Q000235:genetics*; D014018:Tissue Distribution; D015533:Transcriptional Activation; D014481:United States
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator
keywords: AHR; ARNT; Alligator; Transactivation