The Role of miR-182 on FBXW7 Transcript and Protein Expression in NAFLD-related Fibrosis
Nonalcoholic fatty liver disease (NAFLD) is a progressive disease spanning a spectrum of conditions that can include steatosis, inflammation, fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). NAFLD develops in response to environmental and genetic factors, and emerging studies also support a role for epigenetic factors, including microRNAs, in the development and progression of the disease. Using miRNA sequencing, we previously found that expression of miR-182, a miRNA upregulated in HCC, was elevated in fibrotic liver compared to normal liver in NAFLD patients. Using bioinformatics algorithms, we identified the gene encoding F-box and WD repeat domain containing 7 (FBXW7) as a potential target of miR-182. FBXW7 is protective against insulin resistance, hyperglycemia, and glucose intolerance, and previous research demonstrated hepatic downregulation of FBXW7 in obese patients. We hypothesized that miR-182 downregulates FBXW7 in the liver, promoting dysregulation of normal liver function. To address this hypothesis, we sought to determine whether miR-182 functionally interacts with FBXW7. We first found that expression of miR-182 and FBXW7 protein, but not mRNA, was increased in activated LX-2 cells, an immortalized hepatic stellate cell line. Using a luciferase assay, we determined that miR-182 interacted with the 3’ untranslated region of FBXW7 to downregulate its expression. These results demonstrate that miR-182 regulates FBXW7 expression and suggest a pathway by which increased miR-182 expression leads to repression of FBXW7 expression. Ongoing studies are measuring the effects of miR-182 knockdown and overexpression of miR-182 on FBXW7 protein levels.