Sensitive Bioassay for Detecting Dioxins and PCBs

The aryl hydrocarbon receptor (AHR) is a transcription factor that becomes activated when it binds planar aromatic hydrocarbons including PCBs and dioxins. Upon binding a molecule such as a dioxin AHR moves to the nucleus where it complexes with another protein ARNT. The AHR-ARNT complex then up-regulates the transcription of a variety of toxin-degrading enzymes. Recently researchers have discovered a number of other proteins involved in this signaling pathway including ARA9 ARA3 and Src. UW-Madison researchers have developed a highly sensitive biological assay for detecting serious environmental pollutants such as dioxins and polychlorinated biphenyls (PCBs) as well as other molecules that bind to the aryl hydrocarbon receptor. The assay utilizes a transgenic yeast cell line that expresses AHR ARNT and either ARA9 ARA3 or Src (or a combination). These toxin-responsive elements are linked to a reporter gene so that a detectable product is expressed in the presence of planar aromatic hydrocarbon molecules. Technology Applications: 1) Detecting highly toxic environmental contaminants such as dioxins and PCBs 2) Screening drugs that bind to the aryl hydrocarbon receptor (AHR) or interact with the ARA9 ARA3 or Src proteins