Role of MEG3 in Cellular Physiology of Atherosclerosis.

OBJECTIVE: To investigate the role of the lncRNA MEG3 (MEG3) in opposing the biochemical processes thought to be involved in the development of atherosclerosis (AS). METHODS: Thirty patients with AS and thirty healthy control subjects were enrolled in this study. The expression of MEG3, miR-200b-3p and ABCA1 was analyzed by RT-qPCR in the individuals and the macrophages-derived foam cells. Lipid accumulation was detected by oil red O staining. Cholesterol efflux was measured by ELISA assay in the foam cells. Expression of miR-200b-3p was identified by sequencing. Targeting relationships were determined by dual luciferase assay between MEG3 and miR-200b-3p, miR-200b-3p and ABCA1. RESULTS: In the patients with AS, MEG3 and ABCA1 expression were decreased and miR-200b-3p expression was upregulated. Foam cells transfected with an expression vector (pcDNA3.1) containing MEG3 (pcDNA3.1-MEG3) induced decrease of lipid accumulation and increase of cholesterol efflux compared to cells transfected with control plasmid alone. Foam cells transfected by pcDNA3.1-MEG3 also showed decreased miR-200b-3p and increased ABCA1 expression. Interestingly, co-expression of miR-200b-3p partially prevented these effects of MEG3 expression. CONCLUSION: Expression of MEG3 is downregulated in the patients with AS and foam cells. Overexpressed MEG3 may act as an anti-atherosclerotic factor by reducing lipid accumulation and accelerating cholesterol efflux through the miR-200b-3p/ABCA1 axis.

Inhibition of miR-200b-3p alleviates lipid accumulation and promotes cholesterol efflux by targeting ABCA1 in macrophage-derived foam cells.

Atherosclerosis (As) is a chronic cardiovascular disease characterized by abnormal of lipid accumulation and cholesterol efflux. The present study aimed to investigate whether the micro-RNA (miR)-200b-3p could exacerbate As by promoting lipid accumulation and inhibiting cholesterol efflux via ATP-binding cassette transporter A1 (ABCA1) in macrophage-derived foam cells. Blood samples from 30 patients with As and 30 healthy people were collected at Quanzhou First Hospital. RAW264.7 cells were used to establish foam cells using oxidized low-density lipoprotein. The expression of miR-200b-3p and ABCA1 was evaluated by reverse transcription quantitative PCR and western blotting. Lipid accumulation was analyzed by Oil Red O staining and cholesterol content was assessed by ELISA. A targeting relationship between miR-200b-3p and ABCA1 was demonstrated by luciferase reporter assays. Compared with healthy volunteers and RAW264.7 cells, the expression level of miR-200b-3p was significantly increased whereas the expression level of ABCA1 was significantly decreased in patients with As and foam cells. Furthermore, miR-200b-3p expression was negatively correlated with ABCA1 expression in the blood of the patients with As. Lipid content was significantly decreased and cholesterol efflux was significantly increased in foam cells transfected with the miR-200b-3p inhibitor compared with inhibitor control cells. In addition, ABCA1 was shown to be targeted by miR-200b-3p. Furthermore, the lipid content in foam cells transfected with the miR-200b-3p inhibitor and small interfering-ABCA1 was significantly increased, while the cholesterol efflux was significantly decreased compared with foam cells transfected with the miR-200b-3p inhibitor. In conclusion, the findings from the present study indicated that inhibition of miR-200b-3p may alleviate lipid accumulation and promote cholesterol efflux by targeting ABCA1 in macrophage-derived foam cells.