Objective To investigate the effect of nuclear translocation of E2p45 related factor 2 (Nrf2)on the biological activity of melanocytes.Methods Plasmid vectors containing wild-type nrf2 gene (pcDNA-nrf2) and nls-deleted nrf2 gene (pcDNA-nrf2△nls) were constructed.B10BR normal murine melanocytes were classified into three groups,i.e.,untransfected group,wild-type nrf2 group transfected with pcDNA-nrf2,and mutated nrf2 group transfected with pcDNA-nrf2△nls.Each of the above groups were further divided into three subgroups:control subgroup receiving no treatment,hydrogen peroxide (H2O2) subgroup treated with H2O2 of 200 μmol/L for 24 hours,and combined subgroup pretreated with tert-butyl hydroquinone (TBHQ) followed by treatment with H2O2 of 200 μmol/L for 24 hours.Subsequently,methyl thiazolyl tetrazolium (MTT) assay was performed to evaluate the proliferative activity of cells,dopa oxidation assay to determine tyrosinase activity,Transwell assay to estimate cell migration ability,Western blot to quantify the expressions of Nrf2 and his tag fusion protein.Results TBHQ significantly enhanced the nuclear expression of Nrf2 in B10BR cells transfected with pcDNA-nrf2 or pcDNA-nrf2△nls (both P ＜ 0.01).No significant difference was observed in tyrosinase activity between untreated wild-type nrf2 group,mutated nrf2 group,and untransfected group (P ＞ 0.05).There was a statistical decrease in tyrosinase activity in the two H2O2-treated transfected groups compared with the untreated transfected groups (both P ＜ 0.05),and the decrease was reversed by TBHQ pretreatment in the wildtype nrf2 group (P ＜ 0.05),but not in the mutated nrf2 group (P ＞ 0.05).Further more,the proliferative activity of B10BR cells experienced no obvious changes in the wild-type nrf2 group (P ＞ 0.05),but was significantly reduced in the untransfected group (P ＜ 0.05) and mutated nrf2 group (P ＜ 0.01) after the H2O2 treatment compared with the corresponding untreated groups.TBHQ could protect the pcDNA-nrf2-transfected B10BR cells,but not pcDNA-nrf2△nls-transfected B10BR cells,from H2O2-induced oxidative damage.Transwell assay showed no significant difference in migration ability among these nine groups (P ＞ 0.05).Conclusions Abnormal nuclear translocation of Nrf2 could affect antioxidant activity of,proliferative activity of and tyrosinase activity in melanocytes.TBHQ may enhance the tyrosinase activity in,proliferative activity and antioxidant activity of melanocytes via activating the nuclear expression of wild type Nrf2.