Mipu1 Inhibits Lipid Accumulation Through Down-Regulation of CD36 in RAW264.7 Cells

Abstract

Background/Aims: Our recent data indicated that Mipu1 overexpression reduces lipid intake and CD36 expression of macrophages in the presence of oxLDL. However, the mechanism of Mipu1 inhibiting lipid accumulation in macrophages is not elucidated. Methods: Real-time quantitative polymerase chain reaction (PCR) and western blot analysis were used to detect expression of Mipu1 and CD36. The promoter activity of CD36 was studied using luciferase assays. Chromatin immunoprecipitation (ChIP) was used to show the recruitment of Mipu1 onto the CD36 promoter. High-performance liquid chromatography and Dil-labeled lipoprotein were used to detect cholesterol accumulation. Results: Here, we show that CD36 overexpression rescues oxLDL-induced cholesterol accumulation in RAW264.7-Mipu1 cells. Analysis of the mouse CD36 promoter revealed two potential Mipu1-response elements (MRE), one of which (from -237bp to -244bp, ACTTAC) was shown, using mutagenesis and deletion analysis, to be functional. Mipu1 was demonstrated to bind to CD36 promoter, and oxLDL treatment resulted in increases in their interaction as assessed by ChIP. Conclusions: It was demonstrated that Mipu1 inhibited the lipid accumulation of macrophages and it down-regulated CD36 expression in the presence of oxLDL.