title: Short heterodimer partner (SHP) orphan nuclear receptor inhibits the transcriptional activity of aryl hydrocarbon receptor (AHR)/AHR nuclear translocator (ARNT).
abstract: SHP (short heterodimer partner) is an orphan nuclear receptor lacking a DNA binding domain that interacts with nuclear receptors (NR) including thyroid receptor (TR), retinoic acid receptors (RAR and RXR), and estrogen receptors alpha and beta (ERalpha and ERbeta). SHP acts as a negative regulator of these receptors by inhibiting DNA binding and transcriptional activation. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) binds to arylhydrocarbon receptor (AHR), activating the AHR/AHR nuclear translocator (ARNT) heterodimer. We investigated the physical and functional interaction of SHP with AHR/ARNT. In RL95-2 human endometrial carcinoma cells, SHP inhibited TCDD-stimulated reporter activity from the AHR-responsive CYP1A1 and UGT1A6 gene promoters in a concentration-dependent manner. In GST pull-down assays, ARNT interacted directly with SHP in vitro, but AHR did not interact with GST-SHP. SHP inhibited AHR/ARNT-DNA binding in vitro. These results identify ARNT as a novel SHP target. We speculate a role for SHP in the suppression of agonist-activated AHR/ARNT activity.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, Kentucky 40292, USA. carolyn.klinge@louisville.edu
authors.forename: C M
authors.initials: CM
authors.lastname: Klinge
authors.forename: S C
authors.initials: SC
authors.lastname: Jernigan
authors.forename: K E
authors.initials: KE
authors.lastname: Risinger
authors.forename: J E
authors.initials: JE
authors.lastname: Lee
authors.forename: V V
authors.initials: VV
authors.lastname: Tyulmenkov
authors.forename: K C
authors.initials: KC
authors.lastname: Falkner
authors.forename: R A
authors.initials: RA
authors.lastname: Prough
mesh_terms: D000818:Animals; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D001483:Base Sequence; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins; D017930:Genes, Reporter / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D000072317:Polychlorinated Dibenzodioxins / Q000378:metabolism / Q000494:pharmacology; D018336:Receptors, Aryl Hydrocarbon; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects; D014407:Tumor Cells, Cultured
chemical_list: C497396:ARNT protein, human; C497397:Arnt protein, mouse; D017931:DNA Primers; D004268:DNA-Binding Proteins; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D018160:Receptors, Cytoplasmic and Nuclear; D011994:Recombinant Proteins; D014157:Transcription Factors; C099713:nuclear receptor subfamily 0, group B, member 2; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D019363:Cytochrome P-450 CYP1A1