PARP7 represses CYP1A1 expression in MEFs, hepatocytes and Caco-2 cells. AHR ligand induced Cyp1a1 levels are higher in (A) hepatocytes and (B) MEFs isolated from Parp7−/− compared to Parp7+/+ mice. Hepatocytes and MEFs were isolated from livers of Parp7−/− and Parp7+/+ mice and treated with DMSO, 10 nM TCDD, 10 nM FICZ, 200 μM KYN or 10 μM DIM for 6 h. The Cyp1a1 mRNA levels were determined with RT-qPCR. * p < 0.05 two-way ANOVA compared with genotyped-matched control treated hepatocytes or MEFs. #
p < 0.05 two-way ANOVA compared with ligand matched Parp7+/+ hepatocytes or MEFs. (C,D) RNAi-mediated knockdown of PARP7 increased DIM-induced CYP1A1 levels. Caco2 cells were transfected with two different siRNAs targeting PARP7 and treated with DMSO and 10 μM DIM for 6 h. Relative CYP1A1 mRNA and PARP7 mRNA levels were determined with RT-qPCR. * p < 0.05 two-way ANOVA compared with control treated non-targeted (NT) Caco-2 cells. #
p < 0.05 two-way ANOVA compared with DIM-treated NT Caco-2 cells.