RESUMO
Objective To study the relationship between CCAAT/enhancer-binding proteins (C/EBPs) and circadian genes expression in mammals.Methods C/EBP-a 240,280,650,1300 and Rev erb-a promoter-luciferase reporter gene expression vectors were set up,as well as the corresponding report gene stable transfection cell lines were established.The intensity and/or rhythm of report gene expression were observed by testing the biological fluorescent.Results The transcription factor CLOCK/BMAL1 heterodimer activated C/EBP-a via a conserved E-box element in its promoter,and the latter showed circadian oscillation which was E-box dependent.On the other hand,C/EBP-a suppressed Rev-erba transcription.Moreover,GR signaling,a known resetting signal for circadian clock,suppressed C/EBP-a transcription.Conclusion The data highlight the reciprocal feedback regulation between a key transcription factor C/EBP-a and the timing mechanism in cells.