Fig. 8

Obacunone (OB) reduced nuclear factor-2 associated factor 2 (Nrf2) ubiquitinated proteasome degradation. A Expression of Nrf2 and Keap1 in BEAS-2B cells as determined by western blotting. B Expression levels of Nrf2 and HO-1 in BEAS-2B cells as determined by RT-qPCR. C BEAS-2B cells were treated with 50 μg/mL cycloheximide (CHX) and incubated for a specified period. Nrf2 level in BEAS-2B cells as determined by western blotting. D BEAS-2B cells were either left untreated or treated with 10 μM MG132 for 4 h to inhibit the degradation of ubiquitinated proteins. Nrf2 level was determined by western blotting. E BEAS-2B cells were treated with 10 μM MG132 for 4 h, and endogenous ubiquitin-bound Nrf2 and Keap1 were detected. Cell lysates were immunoprecipitated using anti-NRF2 and anti-Keap1 antibodies and imprinted with anti-ubiquitin antibodies. F Diagram showing the mechanism of action of OB. Similar results were obtained from three independent experiments. All data are presented as mean ± SEM (n = 6 for each group). ^#/*P < 0.05, ^##/**P < 0.01, ^# versus control group; * versus LPS group; ns, no significant difference between control and LPS group