A dimer formed by activator protein-1 family proteins c-Jun and Fra1 increases viability of dopaminergic neurons SH-SY5Y

Objective To investigate the roles ofc-Jun/Fra1 dimer in viability ofdopaminergic neurons.Methods (1) Dopaminergic neuron-like cell line SH-SY5Y was cultured in vitro.Cells were lysed for immunoprecipitation to determine whether c-Jun dimerized with Fra1.(2) Cells received treatments were divided into four groups:Jun N-terminal kinase (JNK) inhibitor SP600125 treatment group,mitogen-activated kinase (MEK) 1/2 inhibitor U0126 treatment group,SP600125+U0126 treatment group and control group (treated with dimethyl sulfoxide [DMSO]).Western blotting was performed to detect the c-Jun and Fral expression levels and MTT assay was used to observe the cell viability.(3) Cells infected with adenovirus (Ad) carrying c-Jun or Fra1 genes were divided into three groups:Ad-c-Jun group,Ad-Fra1 group and Ad-c-Jun+Ad-Fra1 group,and cells transfected with GFP were used as control group; immunofluorescence and MTT assay were performed to determine the infectious rate and the cell viability,respectively.Results (1) Co-immunoprecipitation showed that the c-Jun dimerized with Fral in SH-SY5Y cell line.(2) Western blotting indicated that inhibition of JNK by SP600125 reduced c-Jun expression and MEK1/2 by U0126 inhibited Fra1 expression; MTT assay indicated that there were significant differences in the cellular viability among the four groups (F=16.647,P=0.000),the cellular viability in control group obviously differed from that in SP600125 treatment group,U0126 treatment group or SP600125+U0126 treatment group (P＜0.05).(3) Immunofluorescence showed that most of cells infected by adenovirus expressed c-Jun or Fra1.MTT assay indicated that there were significant differences in the cellular viability among the four groups (F=14.543,P=0.000),and there were significant differences in their viabilities between control group and Ad-Fra1 group,and between Ad-Fra1 group and Ad-Fra1+Ad-c-Jun group (P＜0.05).Conclusion The c-Jun and Fra1forming a dimer promotes the viability of dopaminergic neuron-like cells. Key words: Dopaminergic neuron-like cell;  C-Jun;  Fra1;  Viability