Nrf2 Negatively Regulates Melanogenesis by Modulating PI3K/Akt Signaling
Figure 1
Effect of Nrf2 on melanogenesis.
(A) Cellular extracts prepared from cultured normal human epidermal melanocytes (NHEMs), SV40T-transformed human epidermal keratinocytes (SV-HEK) and normal human dermal fibroblasts (NHDFs) were assessed by Western blotting. (B) NHEMs were transduced with an adenovirus expressing Nrf2 or LacZ (control) at the indicated multiplicity of infection (MOI) for 6 h. Cells were replenished and then cultured for a further 3 days. Expression of Nrf2 downstream genes was determined by Western blot analysis. (C) After adenoviral transduction, cells were harvested and spun down. Upper panel shows the pellet color. Lower panel shows melanin content measured by spectrometer. Data are the means ± SD of triplicate measurements (*P<0.01 vs. control). (D) Tyrosinase (TYR) activity was determined and expressed as a percentage of the control. Data are the means ± SD of triplicate measurements (*P<0.01 vs. control). (E) Expression levels of the melanogenic enzymes TYR, tyrosinase-related protein-1 (TRP1) and tyrosinase-related protein-2 (TPR2) were assessed by Western blotting. Actin was used as the loading control. (F) A tyrosinase promoter-luciferase reporter adenovirus was co-transduced with an adenovirus expressing Nrf2 or LacZ (control). The cells were harvested after 2 days for the reporter assay. TYR promoter activity was expressed as a percentage of the control ± SD (*P<0.01 vs. control).