Transcription factor CCAAT CCAAT /enhancer‐binding protein‐β upregulates micro RNA RNA , let‐7f let‐7f ‐1 in human endocervical cells

摘要

Problem In endocervical epithelial cells (End1/E6E7), mi RNA let‐7f plays an important role in the control of innate immunity. The underlying molecular mechanism for let‐7f regulation in these cells remains largely unclear. Methods of study let‐7f was knocked down in End1/E6E7 cells using si RNA , and differential gene expression was analyzed by microarray. Differentially expressed genes were validated by qPCR and Western blot. Expression of let‐7f was studied by qPCR after inhibition of C/ EBP β with betulinic acid ( BA ) and pCMV β plasmid and after overexpression of C/ EBP β with pCMV β+ plasmid. Ch IP assay was performed to confirm binding of C/ EBP β to let‐7f promoter. Levels of Lin28A/B were checked by qPCR after similar treatment. Results let‐7f knockdown (KD) affects the expression of many transcription factors (eg, C/ EBP β) which are important regulators of immune responses. We observed let‐7f‐1 promoter to contain 6 C/ EBP β binding sites. KD of C/ EBP β led to decreased let‐7f expression while overexpression of C/ EBP β increased its expression. Treatment of End1/E6E7 cells with TLR ‐3 ligand, poly(I:C) increased binding of C/ EBP β at binding sites 3, 5, and 6. Expression of Lin28A/B also changed upon inhibition and overexpression of C/ EBP β. Its expression is opposite to that of let‐7f in End1/E6E7 cells. Conclusion let‐7f‐1 is a direct target of transcription factor, C/ EBP β in End1/E6E7 cells.