title: Regulation of pregnane-X-receptor, CYP3A and P-glycoprotein genes in the PCB-resistant killifish (Fundulus heteroclitus) population from New Bedford Harbor.
abstract: Killifish survive and reproduce in the New Bedford Harbor (NBH) in Massachusetts (MA), USA, a site severely contaminated with polychlorinated biphenyls (PCBs) for decades. Levels of 22 different PCB congeners were analyzed in liver from killifish collected in 2008. Concentrations of dioxin-like PCBs in liver of NBH killifish were ∼400 times higher, and the levels of non-dioxin-like PCBs ∼3000 times higher than in killifish from a reference site, Scorton Creek (SC), MA. The NBH killifish are known to be resistant to the toxicity of dioxin-like compounds and to have a reduced aryl hydrocarbon receptor (AhR) signaling response. Little is known about the responses of these fish to non-dioxin-like PCBs, which are at extraordinarily high levels in NBH fish. In mammals, some non-dioxin-like PCB congeners act through nuclear receptor 1I2, the pregnane-X-receptor (PXR). To explore this pathway in killifish, a PXR cDNA was sequenced and its molecular phylogenetic relationship to other vertebrate PXRs was determined. Killifish were also collected in 2009 from NBH and SC, and after four months in the laboratory they were injected with a single dose of either the dioxin-like PCB 126 (an AhR agonist) or the non-dioxin-like PCB 153 (a mammalian PXR agonist). Gills and liver were sampled three days after injection and transcript levels of genes encoding PXR, cytochrome P450 3A (CYP3A), P-glycoprotein (Pgp), AhR2 and cytochrome P450 1A (CYP1A) were measured by quantitative PCR. As expected, there was little effect of PCB exposure on mRNA expression of AhR2 or CYP1A in liver and gills of NBH fish. In NBH fish, but not in SC fish, there was increased mRNA expression of hepatic PXR, CYP3A and Pgp upon exposure to either of the two PCB congeners. However, basal PXR and Pgp mRNA levels in liver of NBH fish were significantly lower than in SC fish. A different pattern was seen in gills, where there were no differences in basal mRNA expression of these genes between the two populations. In SC fish, but not in NBH fish, there was increased mRNA expression of branchial PXR and CYP3A upon exposure to PCB126 and of CYP3A upon exposure to PCB153. The results suggest a difference between the two populations in non-AhR transcription factor signaling in liver and gills, and that this could involve killifish PXR. It also implies possible cross-regulatory interactions between that factor (presumably PXR) and AhR2 in liver of these fish.
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, SE 405 30 Gothenburg, Sweden.
authors.forename: Johanna
authors.initials: J
authors.lastname: Gräns
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, SE 405 30 Gothenburg, Sweden.
authors.forename: Britt
authors.initials: B
authors.lastname: Wassmur
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, SE 405 30 Gothenburg, Sweden.
authors.forename: María
authors.initials: M
authors.lastname: Fernández-Santoscoy
authors.affiliation: Biology Department, MS #32, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
authors.forename: Juliano
authors.initials: J
authors.lastname: Zanette
authors.affiliation: Biology Department, MS #32, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Woodin
authors.affiliation: Biology Department, MS #32, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
authors.forename: Sibel I
authors.initials: SI
authors.lastname: Karchner
authors.affiliation: Office of Research and Development, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, United States Environmental Protection Agency, 27 Tarzwell Drive, Narragansett, RI 02882, USA.
authors.forename: Diane E
authors.initials: DE
authors.lastname: Nacci
authors.affiliation: Office of Research and Development, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, United States Environmental Protection Agency, 27 Tarzwell Drive, Narragansett, RI 02882, USA.
authors.forename: Denise
authors.initials: D
authors.lastname: Champlin
authors.affiliation: Office of Research and Development, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, United States Environmental Protection Agency, 27 Tarzwell Drive, Narragansett, RI 02882, USA.
authors.forename: Saro
authors.initials: S
authors.lastname: Jayaraman
authors.affiliation: Biology Department, MS #32, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Hahn
authors.affiliation: Biology Department, MS #32, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
authors.forename: John J
authors.initials: JJ
authors.lastname: Stegeman
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, SE 405 30 Gothenburg, Sweden. Electronic address: malin.celander@gu.se.
authors.forename: Malin C
authors.initials: MC
authors.lastname: Celander
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D051544:Cytochrome P-450 CYP3A / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D023781:Fundulidae / Q000145:classification / Q000235:genetics*; D005880:Gills / Q000187:drug effects; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008404:Massachusetts; D010802:Phylogeny; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D000077297:Pregnane X Receptor; D011987:Receptors, Steroid / Q000235:genetics* / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D018076:DNA, Complementary; D000077297:Pregnane X Receptor; D011987:Receptors, Steroid; D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls; D051544:Cytochrome P-450 CYP3A
keywords: CYP3A; Fish; NR1I2; P-glycoprotein; PCB; PXR