Investigating Aryl Hydrocarbon and Pregnane X Receptor Modulation

Chemicals, among them, indolepropionic acid (IPA), glutathione (GSH), N-acetyl-cysteine (NAC), Mito-TEMPO, and ketoconazole were from Sigma-Aldrich (St. Louis, MO, USA) unless otherwise stated. IPA was used, 0.4 μM and 0.8 μM, which corresponds to the normal human serum concentration of IPA [40 (link),49 (link),50 (link)]. GSH and NAC antioxidants were used at a final concentration of 5 mM. The mitochondria-targeted antioxidant Mito-TEMPO was used at a concentration of 5 μM. The aryl hydrocarbon receptor (AHR) inhibitor, CH223191, was obtained from MedChemExpress (MCE, Monmouth Junction, NJ, USA) and was applied at a concentration of 10 μM. Pregnane X receptor (PXR) downstream signaling was inhibited using ketoconazole at a final concentration of 25 μM [51 (link),52 (link)]. The Silencer Select siRNAs targeting AHR (AHR—siRNA ID: s1198) and PXR (NR1I2—siRNA ID: s16910) and the negative control siRNA #1 (cat.no. 4390843) were obtained from Thermo Fisher Scientific (Waltham, MA, USA) and each was used at a final concentration of 30 nM.