Hypercholesterolemia is an important risk factor for coronary heart disease. Although a lot of research has been conducted, the regulation of cholesterol metabolism is still largely unknown. Some miRNAs have been found to play critical role in the cholesterol metabolism. MiR-98 is a miRNA whose function has been reported mainly in tumorigenesis. In this study, we elucidate a novel role of miR-98 in cholesterol metabolism. We found that the expression of miR-98 was decreased significantly in hypercholesterolemic patients compared with healthy control subjects. Furthermore, we identified that SREBP-2, an important transcriptional factor in cholesterol metabolism, was a direct target of miR-98. Overexpression of miR-98 significantly repressed the 3'-UTR reporter activities of SREBP-2 in a dose-dependent manner in HepG2 cells, while the effect of miR-98 was blocked when the binding site of miR-98 within the SREBP-2 3'-UTR was mutated. And overexpression of miR-98 reduced both the mRNA and protein levels of HMGCR and LDLR significantly in vitro, which are two target genes of SREBP-2. Furthermore, MiR-98 overexpression reduced the intracellular total cholesterol levels dramatically. Moreover, we overexpressed the miR-98 by lentiviral tail vein injection in vivo. Compared with the control mice, the miR-98 overexpression mice showed lower serum cholesterol level and decreased SREBP-2, HMGCR as well as LDLR expression. Our data confirmed that reduced expression of miR-98 potentially contributes to disturbance of cholesterol metabolism. MiR-98 might be a novel therapeutic target to hypercholesterolemia.
Keywords: Cholesterol metabolism; HMG-CoA reductase; MiR-98; SREBP-2.
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