Aberrant hepatic microRNA expression in nonalcoholic fatty liver disease.

BACKGROUND/AIM: Emerging evidence suggests that microRNA (miRNA) mediated gene regulation influences the maintenance of metabolic homeostasis, particularly the states of obesity and insulin resistance, thereby providing a potential link between miRNAs and nonalcoholic fatty liver disease (NAFLD). METHODS: Sprague-Dawley rats fed a high-fat diet (HFD) were used to establish a rat model of NAFLD. The miRNA expression profile of liver tissues was evaluated using Illumina HiSeq deep sequencing. Selected miRNAs were then validated by real-time PCR at both 4- and 12-week time points. Furthermore, the expression levels of these miRNAs were assessed in HepG2 cells and human hepatocytes treated with free fatty acids (FFAs) and proinflammatory factors (tumour necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). RESULTS: Our results showed that consumption of a HFD for 4 weeks caused simple steatosis, which progressed to steatohepatitis at 12 weeks. miRNA deep sequencing analysis identified 44 known up-regulated miRNAs (fold change >1.5) and 12 down-regulated miRNAs (fold change <0.5). Among the abnormally expressed miRNAs, miR-200a, miR-200b, miR-200c, miR-146a, miR-146b and miR-152 were up-regulated both in vitro and vivo. Interestingly, the expression levels of these six miRNAs were increased in HepG2 cells and human hepatocytes after treatment with FFAs and proinflammatory factors. CONCLUSION: These findings suggest a critical role for miRNAs in the pathogenesis of NAFLD.