Fig. 5

TARDBP promoter is activated by AHR agonism. a Schematic representation of sense AHRE consensus sites “GCGTG” (red flags) of human CYP1A1 and CYP1B1 AHR responsive genes and the ALS-relevant gene, TARDBP. Green boxes are exons. b In human H4 cells, treatment (72 h) with the AHR agonist 6-Formylindolo[3,2-b]carbazole (FICZ; 0.5 μM) increased luminescence from positive control luciferase reporter CYP1B1_-3.8 kb/luc2, and human TARDBP_-4.1 kb/luc2. c In M17 cells, treatment (72 h) with the AHR agonist 6-Formylindolo[3,2-b]carbazole (FICZ; 0.5 μM) increased luminescence from the human TARDBP_-4.1 kb/luc2 luciferase reporter. This FICZ-triggered increase of TARDBP_-4.1 kb/luc2 is blocked with the AHR antagonist CB7993113 (10 μM). N = 4. An M17 doxycycline-inducible shAHR line was generated that displayed a 73% decrease in endogenous AHR mRNA transcript assessed by qPCR d; N = 3. By expressing the luciferase reporters in these M17.shAHR cells e, the increase in luminescence from the TARDBP promoter, caused by 0.5 μM FICZ treatment, was significantly blocked by inducing shAHR (using 1 μg/ml doxycycline). N = 4. f The potent environmental toxins the dioxin-like 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD; 0.01uM), the polyaromatic hydrocarbon Benzo[a]pyrene (B(a)P; 10 μM) and the bacterial toxin pyocyanin (Pyo; 5 μM) activate TARDBP expression. B(e)P, the non-toxic B(a)P congener did not activate the TARDBP promoter through the AHR. N = 4. For each, mean ± SEM, ANOVA w/Tukey’s; *** P < 0.001, ** P < 0.01, * P < 0.05