Cloning and specificity analysis of miR-122 Promoters

Objective To predict and clone miR-122,and to analyze its specificity.Methods The putative promoter regions of miR-122 were extracted from hepatocarcinoma cell lines,Huh-7 and HepG2,and cloned into plasmid pGL4.17,which contains the reporter gene of Firefly luciferase (Fluc).The transcription-promoting capacity of these putative promoters of miR-122 was detected.Results We successfully predicted and cloned miR-122 promoter sequences.The transcription-promoting capacity of the putative promoter of miR-122 was detected after it was transfected into the cells.The expression of Fluc in HeLa cells transfected with the constructed plasmid pGL4.17-P 1,which contains the putative promoter 1 of miR-122 ( P1 ),was significantly increased than that in the control cells ( t =0.000 21,P ＜ 0.01 ; t =0.000 38,P ＜ 0.01 ) detected by Dual and Single-Luciferase reporter assay system,respectively.Conclusion The distinction of miR-122 expression in cell lines of Huh-7 and HepG2 was not related with the presence of miR-122 promoters.Reporter gene controlled by the promoter of miR-122 was also expressed in non-hepatic cells.These results suggested that the promoters of miR122 showed no hepatic specificity. Key words: miR- 122 ;  Promoter ;  Hepato- specificity ;  Reporter gene