Figure 8.

Oxidative stress does not overcome the translational repression motif that exists inside the open reading frame of Nrf2. HEK293T cells transfected with the Nrf2 translation reporter (Luc2–Sg3Nrf2) were treated 24 h after transfection with increasing doses of three inducers of oxidative stress: A, hydrogen peroxide; B, tert-butyl hydro peroxide; and C, paraquat, to evaluate the induction of luciferase translation and compared against apigenin. 24 h after the treatment with inducers of oxidative stress, the fold change in expression of luciferase was calculated against the basal expression of Luc2–Nrf2Sg3 in cells treated with DMSO only as a negative control (n = 6). The statistical significance of the difference in the levels of expression of luciferase in cells treated with apigenin or inducers of oxidative stress versus untreated cells is indicated by **, p < 0.01. The expression was normalized against the cell viability data measured with Cell-titer Glo® after the treatment. The range of concentrations for each inducer of oxidative stress was selected around known reported concentrations that induce oxidative stress in HEK293T cells (35, 73, 74).