Linked Life Data

18086832

Source:http://linkedlifedata.com/resource/pubmed/id/18086832

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2008-2-25
pubmed:abstractText
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that mediates most biological responses to 2,3, 7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related aromatic hydrocarbons. Although the role of the AHR in control of drug metabolism and endocrine disruption is partly understood, we know little about the regulation of the AHR itself by endocrine factors. Our work with hypophysectomized rats suggested that hepatic AHR protein level is positively regulated by pituitary-dependent factors. A current hypothesis is that adrenal glucocorticoids elevate AHR expression and enhance responsiveness to AHR agonists. Dexamethasone (DEX) at concentrations that activate the glucocorticoid receptor (GR) increased AHR mRNA, protein, and TCDD-binding by approximately 50% in Hepa-1 mouse hepatoma cells. This response was blocked by the GR antagonist 17beta-hydroxy-11beta-[4-dimethylamino phenyl]-17alpha-[1-propynyl]estra-4,9-dien-3-one (RU486), suggesting GR involvement. This small magnitude increase in AHR levels was functionally significant; pretreatment of Hepa-1 cells with DEX caused a 75% increase in the maximum induction of an AHR-activated luciferase reporter plasmid by TCDD. A luciferase reporter under control of the proximal 2.5 kilobases of the mouse Ahr 5'-flanking region and promoter was induced approximately 2.5-fold by DEX when cotransfected with a mouse GR expression plasmid. This is the first demonstration that glucocorticoids increase AHR levels in hepatoma cells via a GR-dependent transcriptional mechanism, suggesting a novel aspect of cross-talk between the AHR and the GR.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
1521-009X
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
36
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
543-51
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
Regulation of aryl hydrocarbon receptor expression and function by glucocorticoids in mouse hepatoma cells.
pubmed:affiliation
Department of Pharmacology and Toxicology, Medical Sciences Building, University of Toronto, Toronto, ON, Canada M5S 1A8.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't