[Mechanism of microRNA-29a regulating steatosis in the human hepatocyte via targeting silent mating type information regulation 2 homolog-1].

OBJECTIVE:To investigate the expression of microRNA-29 a(miR-29 a) in the human steatotic hepatocyte model and the mechanism of targeting silent mating type information regulation 2 homolog-1(Sirt1)to regulate fat deposition of steatotic hepatocyte. METHODS:The nonalcoholic fatty liver cell model was induced by a mixture of oleic acid and palmitic acid. After successful validation model, the expression of miR-29 a and Sirt1 was measured by PCR. The target genes of miR-29 a was predicted in biological system. MiR-29 a mimic and miR-29 a inhibitor were transfected into hepatocytes, and then established the human steatotic hepatocyte model, the result of oil red O staining and triglyceride(TG)lipid content were observed, the expression of Sirt1 mRNA and protein were detected by qRT-PCR and Western blotting, respectively. RESULTS:The steatosis hepatocyte model was successfully established. Compared with control group, the relative expression of miR-29 a and triglyceride increased significantly(P<0. 01), while the relative expression of Sirt1 decreased significantly(P<0. 01) in the model group. Sirt1 was a target gene of miR-29 a. After transfection, the lipid droplet and the deposition of fat increased obviously in miR-29 a mimic group than those in the control group. TG content in miR-29 a mimic group increased significantly(P<0. 05), the expression of miR-29 a increased significantly(P<0. 01), while the expression of Sirt1 mRNA decreased significantly(P<0. 05), and the expression of Sirt1 protein showed a downtrend. On the contrary, after the inhibition of miR-29 a expression, the lipid droplets in miR-29 a inhibitor group were relatively reduced, the fat deposition was alleviated. The TG content was significantly decreased(P<0. 05), the expression of miR-29 a in the cells was effectively inhibited(P<0. 01), while the expression of Sirt1 mRNA was significantly increased(P<0. 05), and Sirt1 protein was on an upward compared with the control group. CONCLUSION:The expression of miR-29 a is significantly increased in the nonalcoholic fatty liver cell model. Upregulation of miR-29 a negatively regulates the expression of Sirt1, thus promoting fat deposition of steatotic hepatocyte.