Fig. 8

Curcumin induced Nrf2 degradation by mediating the interaction of Nrf2 with the GSK-3β/β-TrCP axis. A AsT cells were transfected with V5-GSK3β S9A and/or Flag-β-TrCP for 24 h. V5, FLAG, GSK3β, β-TrCP, Nrf2 and HO-1 expression were examined by immunoblotting. B AsT cells were treated with 12.5 and 25 μM curcumin for 24 h before cell lysates were collected. Anti-Nrf2 immunoprecipitates were analyzed by immunoblot with anti-Nrf2 and anti-GSK3β, anti-β-TrCP and anti-ubiquitin antibodies for detection of Nrf2-conjugated GSK3β, β-TrCP and ubiquitin, whole protein lysates were collected and p-Akt Ser-473, Akt, p-GSK3β S9, GSK3β, β-TrCP, Nrf2 and HO-1 and β-actin expression were examined by immunoblotting. C AsT cells were transfected with V5-GSK3β S9A and/or Flag-β-TrCP for 24 h. Cell viabilities were detected by staining with MTT assay. AsT cells were treated with 40 μM LY294002 or 5 μM wortmannin for 24 h. D Cell lysates were collected and p-Akt Ser-473, Akt, p-GSK3β S9, GSK3β, Nrf2 and HO-1 and β-actin expression were examined by immunoblotting. E Cell viabilities were detected by staining with MTT assay. The data are expressed as the mean ± SD of three independent experiments (n = 9). *p < 0.05, **p < 0.01 vs control