Profiling transcription factor transactivation with P450 metabolism integration
Profiling chemical effects on transcription factor activity can help characterize the mechanisms by which chemicals may perturb biological systems. The Attagene cis-FACTORIAL™ assay uses a reporter system to detect transactivation of 46 transcription factors to provide a quantitative assessment of chemical effects. A new version of this assay, CYP-FACTORIAL, adds nine key CYP450 enzymes to enable the evaluation of chemical effects on transcription factor activity with and without CYP-mediated Phase 1 metabolism. These two complementary assay formats support a better understanding of whether CYP-mediated oxidation results in an altered bioactivity profile between parent and metabolite compounds. To explore the application of this system to predicting toxicity, NIEHS and Attagene collaborators tested 24 chemicals of regulatory concern in both systems. Profiling across all 46 transcription factors produced toxicity signatures for chemicals, and applying a biological read-across approach identified chemicals with similar effects. Additionally, profiles for “toxic” vs. “non-toxic” chemicals yielded insight into the biological mechanisms underlying adversity. This study exemplifies how integrating metabolism into a multiplexed in vitro assay system can provide additional mechanistic insight needed to understand chemical-elicited bioactivity, thereby facilitating the development of human-relevant test systems. A poster describing this work (Karmaus et al.) was presented at the 12th World Congress on Alternatives and Animal Use in the Life Sciences, and a manuscript is under development.