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Mipu1 inhibits lipid accumulation through down-regulation of CD36 in RAW264.7 cells
Shun-Lin Qu1, Wen-Jing Fan, Chi Zhang
1Post-doctoral Mobile Stations for Basic Medicine, Institute of Cardiovascular Disease and Key Lab for Arteriosclerology of Hunan Province, University of South China, Hengyang City, China.
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.
Insights
Mipu1 protein inhibits macrophage lipid accumulation by down-regulating CD36 expression, a key factor in cholesterol buildup. This study elucidates the mechanism behind Mipu1
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Macrophage lipid accumulation, particularly from oxidized low-density lipoprotein (oxLDL), is central to atherosclerosis.
- Mipu1 protein's role in reducing lipid intake and CD36 expression in macrophages has been observed.
- The precise mechanism by which Mipu1 inhibits lipid accumulation in macrophages remains unclear.
Purpose of the Study:
- To elucidate the mechanism by which Mipu1 inhibits lipid accumulation in macrophages.
- To investigate the role of CD36 expression in Mipu1-mediated lipid reduction.
- To determine if Mipu1 directly interacts with the CD36 promoter.
Main Methods:
- Quantitative PCR and Western blot to assess Mipu1 and CD36 expression.
- Luciferase assays to evaluate CD36 promoter activity.
- Chromatin immunoprecipitation (ChIP) to confirm Mipu1 binding to the CD36 promoter.
- High-performance liquid chromatography and Dil-labeled lipoprotein assays to quantify cholesterol accumulation.
Main Results:
- CD36 overexpression reversed oxLDL-induced cholesterol accumulation in Mipu1-expressing cells.
- A functional Mipu1-response element (MRE) was identified in the mouse CD36 promoter (-237bp to -244bp).
- Mipu1 was shown to bind directly to the CD36 promoter, with binding increasing upon oxLDL treatment.
Conclusions:
- Mipu1 effectively inhibits lipid accumulation in macrophages.
- Mipu1 down-regulates CD36 expression in macrophages exposed to oxLDL.
- Mipu1 exerts its inhibitory effect on lipid accumulation through direct interaction with the CD36 promoter.
