AICAR stimulates HO-1 promoter activity and nuclear factor-erythroid 2-related factor 2 (Nrf2) expression in HUVECs. A: AICAR stimulated HO-1 promoter activity. Cells were cotransfected with a HO-1 promoter construct (E1) or a mutated HO-1 promoter construct (M739) and a Renilla luciferase construct, treated with AICAR (0.5 mM) for 8 h, and then analyzed for luciferase activity. In some experiments, a dominant negative mutant (dn)Nrf2 construct was cotransfected into cells. B: concentration-dependent effect of AICAR (0.1–1.0 mM for 8 h) on Nrf2 protein expression. C: time course of Nrf2 protein expression after the administration of AICAR (0.5 mM). D: Iodo inhibited AICAR-mediated Nrf2 protein expression. Cells were pretreated with Iodo (0.3 μM) for 30 min and then treated with AICAR (0.5 mM) for 8 h. Nrf2 protein expression was quantified by scanning densitometry, normalized with respect to β-actin, and expressed relative to that of control, untreated cells. Results are means ± SE of 3–6 experiments. *Statistically significant effect of AICAR.