Human MicroRNA-548p Decreases Hepatic Apolipoprotein B Secretion and Lipid Synthesis
Objective—MicroRNAs (miRs) play important regulatory roles in lipid metabolism. Apolipoprotein B (ApoB), as the only essential scaffolding protein in the assembly of very-low-density lipoproteins, is a target to treat hyperlipidemia and atherosclerosis. We aimed to find out miRs that reduce apoB expression.
Approach and Results—Bioinformatic analyses predicted that hsa-miR-548p can interact with apoB mRNA. MiR-548p or control miR was transfected in human and mouse liver cells to test its role in regulating apoB secretion and mRNA expression levels. Site-directed mutagenesis was used to identify the interacting site of miR-548p in human apoB 3′-untranslated region. Fatty acid oxidation and lipid syntheses were examined in miR-548p overexpressing cells to investigate its function in lipid metabolism. We observed that miR-548p significantly reduces apoB secretion from human hepatoma cells and primary hepatocytes. Mechanistic studies showed that miR-548p interacts with the 3′-untranslated region of human apoB mRNA to enhance post-transcriptional degradation. Bioinformatic algorithms suggested 2 potential binding sites of miR-548p on human apoB mRNA. Site-directed mutagenesis studies revealed that miR-548p targets site I involving both seed and supplementary sequences. MiR-548p had no effect on fatty acid oxidation but significantly decreased lipid synthesis in human hepatoma cells by reducing HMGCR and ACSL4 enzymes involved in cholesterol and fatty acid synthesis. In summary, miR-548p reduces lipoprotein production and lipid synthesis by reducing expression of different genes in human liver cells.
Conclusions—These studies suggest that miR-548p regulates apoB secretion by targeting mRNA. It is likely that it could be useful in treating atherosclerosis, hyperlipidemia, and hepatosteatosis.
- Received November 6, 2016.
- Accepted March 10, 2017.
- © 2017 American Heart Association, Inc.