Abstract 573: Human Microrna-548p Decreases apoB Secretion and Lipid Synthesis

Abstract

Objective: MicroRNAs (miRs) play important regulatory roles in lipid and lipoprotein metabolism. 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: Bioinformatics analyses predicted that hsa-miR-548p can interact with apoB mRNA.MiR-548p mimic and control were transfected in human and mouse hepatoma cell lines 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. Results: Experimentally, we observed that miR-548p significantly reduces apoB secretion from human hepatoma cells in time and dose dependent manner. Mechanistic studies showed that miR-548p interacts with the 3′-untranslated region of human apoB mRNA to enhance posttranscriptional degradation. Bioinformatics algorithms suggested two potential binding sites of miR-548p on human apoB mRNA. Site-directed mutagenesis studies revealed that miR-548p targets site II 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 the expression of 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 hepatoma cells. Conclusion: These studies suggest that miR-548p could be useful in treating atherosclerosis, hyperlipidemia and hepatosteatosis.