title: Novel role of hnRNP-A2/B1 in modulating aryl hydrocarbon receptor ligand sensitivity.
abstract: The aryl hydrocarbon receptor (AHR) is responsible for susceptibility to its ligand-dependent responses. However, the effect of non-AHR factors is less clear. To explore the non-AHR factors, we used two mouse strains with different AHR genetic variants, namely C3H/lpr and MRL/lpr strains with Ala and Val as the 375th amino acid residue, respectively. To assess the contribution of AHR alone, COS-7 cells transiently expressing AHR from each strain were treated with 6-formylindolo[3,2-b]carbazole (FICZ) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and xenobiotic-responsive element (XRE)-driven reporter gene activities were measured. FICZ-EC50 values for the C3H/lpr and MRL/lpr AHR-mediated transactivation were 0.023 and 0.046 nM, respectively, indicating a similar susceptibility in both AHR genotypes. In contrast, C3H/lpr AHR was fourfold more sensitive to TCDD than MRL/lpr AHR. By a pull-down assay using a XRE-containing PCR product as bait and the hepatic nuclear extracts of both FICZ-treated mouse strains, we identified two interacting proteins as heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP-A2) and its splicing variant (hnRNP-A2b). Immunoprecipitation assays demonstrated the AHR interaction with hnRNP-A2/B1. When hnRNP-A2 was co-expressed with the MRL/lpr or C3H/lpr AHR in COS-7, FICZ treatment decreased EC50 to about threefold in both AHR genotypes, compared with EC50 in AHR alone. Similarly, hnRNP-A2b co-expression also lowered the FICZ-EC50 values. In TCDD-treated COS-7, responses depended on the AHR genotype; while no change in TCDD-EC50 was observed for C3H/lpr AHR when hnRNP-A2 was co-expressed, the value was reduced to nearly tenfold for MRL/lpr AHR. Co-transfection with hnRNP-A2b attenuated the AHR sensitivity to TCDD. In conclusion, the hnRNP-A2/B1 interacting with AHR may be a modulator of the AHR ligand sensitivity.
authors.affiliation: Department of Life and Nanopharmaceutical Science, Kyung Hee University, Hoegi Dong, Dongdaemun-Gu, Seoul, 130-701, Korea.|Department of Biology, Kyung Hee University, Hoegi Dong, Dongdaemun-Gu, Seoul, 130-701, Korea.
authors.forename: See-Wun
authors.initials: SW
authors.lastname: Cho
authors.affiliation: Graduate School of Science, Hiroshima University, Hiroshima, Japan.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Miura
authors.affiliation: Department of Pathogenomics, Ehime University Graduate School of Medicine, Toon, Japan.
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Miyazaki
authors.affiliation: Department of Pathogenomics, Ehime University Graduate School of Medicine, Toon, Japan.|Department of Histopathology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Nose
authors.affiliation: Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, Japan.
authors.forename: Hisato
authors.initials: H
authors.lastname: Iwata
authors.affiliation: Department of Life and Nanopharmaceutical Science, Kyung Hee University, Hoegi Dong, Dongdaemun-Gu, Seoul, 130-701, Korea. eykim08@khu.ac.kr.|Department of Biology, Kyung Hee University, Hoegi Dong, Dongdaemun-Gu, Seoul, 130-701, Korea. eykim08@khu.ac.kr.
authors.forename: Eun-Young
authors.initials: EY
authors.lastname: Kim
mesh_terms: D000818:Animals; D019556:COS Cells; D002227:Carbazoles / Q000494:pharmacology; D002522:Chlorocebus aethiops; D005838:Genotype; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000378:metabolism*; D047468:Immunoprecipitation; D008024:Ligands; D051379:Mice; D008809:Mice, Inbred C3H; D019463:Mice, Inbred MRL lpr; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics*; D020218:Response Elements / Q000235:genetics; D014162:Transfection
chemical_list: C111855:6-formylindolo(3,2-b)carbazole; D002227:Carbazoles; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D008024:Ligands; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon
keywords: AHR; C3H/lpr; FICZ; MRL/lpr; Sensitivity; TCDD; hnRNP-A2/B1