Novel fluorescent and secreted transcriptional reporters for quantifying activity of the xenobiotic sensor aryl hydrocarbon receptor (AHR)

Aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor that plays a critical role in diverse biological processes, including xenobiotic metabolism, carcinogenesis, and physiological functions such as regulation of the immune system and cell differentiation. To improve studies of AHR activity, we constructed two new reporter genes: a fluorescent GFP-tagged histone 2B (XRE-H2B-eGFP) and a secreted nanoluciferase (XRE-pNL1.3[secNluc]). Here, we demonstrate how these reporters can be used to monitor AHR activity in different types of cells, including human primary trophoblasts and cell lines, following incubation with a strong AHR ligand, benzo[a]pyrene (B[a]P), or an AHR inhibitor (CH223191). Compared to vehicle control cells, a significant increase in AHR activity was observed in cells treated with 0.5 and/or 2 µM B[a]P and a significant decrease was detected in response to treatment with 3 µM CH223191. These new plasmids have great potential for use in a variety of applications, such as screening for endogenous or exogenous ligands of AHR.