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Proc Natl Acad Sci U S A. 2002 Nov 12;99(23):14694-9. Epub 2002 Oct 30.

A ligand for the aryl hydrocarbon receptor isolated from lung.

Author information

1
Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin, Madison 53706, USA.

Abstract

The aryl hydrocarbon receptor (AHR) is a ligand-inducible transcription factor that is best known because it mediates the actions of polycyclic and halogenated aromatic hydrocarbon environmental toxicants such as 3-methylcholanthrene and 2,3,7,8-tetrachlorodibenzo-p-dioxin. We report here the successful identification of an endogenous ligand for this receptor; approximately 20 microg was isolated in pure form from 35 kg of porcine lung. Its structure was deduced as 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester from extensive physical measurements and quantum mechanical calculations. In a reporter gene assay, this ligand activates the AHR with a potency five times greater than that of beta-naphthoflavone, a prototypical synthetic AHR ligand. 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester competes with 2,3,7,8-[(3)H]tetrachlorodibenzo-p-dioxin for binding to human, murine, and fish AHRs, thus showing that AHR activation is caused by direct receptor binding, and that recognition of this endogenous ligand is conserved from early vertebrates (fish) to humans.

PMID:
12409613
PMCID:
PMC137481
DOI:
10.1073/pnas.232562899
[Indexed for MEDLINE]
Free PMC Article

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