[ let-7f microRNA functions as a negative regulator of HNF4a expression in human adipose tissue-derived stem cells]

microRNAs [miRNAs] are noncoding RNAs that function as key regulators of diverse biological activities such as cellular metabolism, cell proliferation and cell cycle regulation. Recent studies have indicated the high potential of these small molecules to control stem cell differentiation into desired cells. The aim of present study is to investigate the possible effect of let-7f on expression of hepatic nuclear factor 4 alpha [HNF4a] and some hepatic specific factors such as albumin [ALB], alpha fetoprotein [AFP], cytokeratin18 [CK18] and cytokeratin19 [CK19] in human adipose tissue derived stem cells [hADSCs]. ADSCs were isolated from human adipose tissue using collagenase type I and were transduced by recombinant lentiviruses that contained human inhibitor let-7f and Scramble [negative control]. Afterward, the expressions of HNF4a, ALB, AFP, CK18 and CK19 were evaluated by Real-time PCR at different time points. Transduction efficiency of lentiviral vectors into ADSCs was more than 80% as judged by the expression of the GFP reporter gene. Real-time PCR analysis revealed that inhibition of let-7f in hADSCs resulted in significant up regulation of hepatic specific genes compared with the negative control. The expression level of HNF4a also increased in experimental cells at day 14, which supported the suppression of HNF4a expression by let-7f. The results of this study identified let-7f as a negative regulator of HNF4a expression in hADSCs and increased the expression of hepatocyte specific factors through silencing of let-7f. Therefore, suppression of let-7f could be a considerable tool for hepatic differentiation of hADSCs