title: Characterization of the activated form of the aryl hydrocarbon receptor in the nucleus of HeLa cells in the absence of exogenous ligand.
abstract: The aryl hydrocarbon receptor (AhR) is known to mediate 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced toxic effects. Immunocytochemical studies revealed that AhR in HeLa cells is localized throughout the cell. Upon TCDD treatment most of the cytoplasmic receptor is translocated into the nucleus in a time-dependent manner. A significant amount of AhR was found to be tightly associated with the nuclear fraction of untreated HeLa cells. The level of receptor in the nuclear fraction was approximately 16% of the total cellular receptor pool. Further characterization of AhR heterocomplex from the HeLa nuclear fraction by sucrose density gradient analysis revealed that the AhR was present in the 6 S form, and that the nuclear AhR could be coimmunoprecipitated using anti-Arnt mAb. The ability of the AhR to specifically interact with dioxin-responsive elements (DRE) was demonstrated utilizing wild-type and two mutant DREs in gel shift assays. These results would suggest that, in HeLa cells, the AhR-Arnt heterodimer is associated with the nuclear fraction under normal culture conditions. Therefore, HeLa cells can be used as a model system to study the biochemical and molecular function of the Ah receptor and the process that leads to activation of the AhR in the absence of exogenous ligand.
authors.affiliation: Department of Veterinary Science, Pennsylvania State University, University Park 16802, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Singh
authors.forename: N G
authors.initials: NG
authors.lastname: Hord
authors.forename: G H
authors.initials: GH
authors.lastname: Perdew
mesh_terms: D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D001483:Base Sequence; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D004268:DNA-Binding Proteins; D006367:HeLa Cells; D006801:Humans; D008024:Ligands; D008969:Molecular Sequence Data; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D011233:Precipitin Tests; D018336:Receptors, Aryl Hydrocarbon / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: C497396:ARNT protein, human; D004268:DNA-Binding Proteins; D008024:Ligands; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D014157:Transcription Factors; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator