Aryl Hydrocarbon Receptor (AhR)

The Aryl hydrocarbon receptor is a member of the family of basic-helix-loop-helix transcription factors. Halogenated aromatic hydrocarbons, represented by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), are environmental pollutants that are produced by minor side-reactions in chemical manufacturing processes and by combustion of waste materials.

These chemicals cause potent and pleiotropic toxicity, including teratogenesis, immune suppression, epithelial disorders, and tumor production in experimental animals. At the molecular level, aldehyde dehydrogenase, quinone reductase, and various drug-metabolizing enzymes are induced by the chemicals in some cultured cells and some tissues of experimental animals. All these biologic effects are thought to be mediated by an intracellular aryl hydrocarbon receptor (AHR).