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A Subregion of Reelin Suppresses Lipoprotein-Induced Cholesterol Accumulation in Macrophages.

ABSTRACT: Activation of apolipoprotein E receptor-2 (apoER2) and very low density lipoprotein receptor (VLDLR) inhibits foam cell formation. Reelin is a ligand of these receptors. Here we generated two reelin subregions containing the receptor binding domain with or without its C-terminal region (R5-6C and R5-6, respectively) and studied the impact of these peptides on macrophage cholesterol metabolism. We found that both R5-6C and R5-6 can be secreted by cells. Purified R5-6 protein can bind apoER2 and VLDLR. Overexpression of apoER2 in macrophages increased the amount of R5-6 bound to the cell surface. Treatment of macrophages with 0.2 ?g/ml R5-6 elevated ATP binding cassette A1 (ABCA1) protein level by ~72% and apoAI-mediated cholesterol efflux by ~39%. In addition, the medium harvested from cells overexpressing R5-6 or R5-6C (R5-6- and R5-6C-conditioned media, respectively) also up-regulated ABCA1 protein expression, which was associated with accelerated cholesterol efflux and enhanced phosphorylation of phosphatidylinositol 3 kinase (PI3K) and specificity protein-1 (Sp1) in macrophages. The increased ABCA1 expression and cholesterol efflux by R5-6- and R5-6C-conditioned media were diminished by Sp1 or PI3K inhibitors mithramycin A and LY294002. Further, the cholesterol accumulation induced by apoB-containing, apoE-free lipoproteins was significantly less in macrophages incubated with R5-6- or R5-6C-conditioned medium than in those incubated with control conditioned medium. Knockdown of apoER2 or VLDLR attenuated the inhibitory role of R5-6-conditioned medium against lipoprotein-induced cholesterol accumulation. These results suggest that the reelin subregion R5-6 can serve as a tool for studying the role of apoER2 and VLDLR in atherogenesis.

SUBMITTER: Okoro EU

PROVIDER: S-EPMC4552883 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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A Subregion of Reelin Suppresses Lipoprotein-Induced Cholesterol Accumulation in Macrophages.

Okoro Emmanuel U EU Zhang Hongfeng H Guo Zhongmao Z Yang Fang F Smith Carlie C Yang Hong H

PloS one 20150828 8

Activation of apolipoprotein E receptor-2 (apoER2) and very low density lipoprotein receptor (VLDLR) inhibits foam cell formation. Reelin is a ligand of these receptors. Here we generated two reelin subregions containing the receptor binding domain with or without its C-terminal region (R5-6C and R5-6, respectively) and studied the impact of these peptides on macrophage cholesterol metabolism. We found that both R5-6C and R5-6 can be secreted by cells. Purified R5-6 protein can bind apoER2 and V ...[more]

PMID: 26317415

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Project description:Atherosclerosis (AS), a major cause of cardiovascular disease, has developed into a serious challenge to the health system. The long non?coding RNA (lncRNA) metastasis associated lung adenocarcinoma transcript 1 (MALAT1) is associated with the pathogenesis of AS. However, whether MALAT1 can affect cholesterol accumulation in macrophages during AS progression, and the potential molecular mechanism involved in this progression have not been elucidated. In the present study, the mRNA expression level of MALAT1 was measured using reverse transcription?quantitative PCR (RT?qPCR) and the protein expression level was detected via western blot analysis. Oil Red O staining was used for detecting lipid accumulation in macrophages. Bioinformatics, dual?luciferase reporter and RT?qPCR assays were used to investigate the relationship between MALAT1 and the microRNA (miR)?17?5p/ATP?binding cassette transporter A1 (ABCA1) axis. The present results suggested that the MALAT1 expression level was significantly decreased in patients with AS and in oxidized low?density lipoprotein (ox?LDL)?stimulated macrophages. Knockdown of MALAT1 increased ox?LDL uptake, lipid accumulation and the total cholesterol (T?CHO) level in ox?LDL?induced macrophages. In addition, MALAT1 inhibition significantly decreased the mRNA and protein expression levels of scavenger receptor (SR) class B member 1, apolipoprotein E (ApoE) and ABCA1. However, MALAT1 increased the expression level of SR class A. Subsequently, the present study investigated whether MALAT1 could target miR?17?5p to regulate the expression level of ABCA1, which is involved in cholesterol efflux from macrophages. The present results suggested that inhibition of miR?17?5p reversed the effects of MALAT1 knockdown on T?CHO content, and protein expression levels of ApoE and ABCA1 in ox?LDL?stimulated macrophages. In summary, knockdown of MALAT1 may promote cholesterol accumulation by regulating the miR?17?5p/ABCA1 axis in ox?LDL?induced THP?1 macrophages.

Dataset Information

A Subregion of Reelin Suppresses Lipoprotein-Induced Cholesterol Accumulation in Macrophages.

Publications

A Subregion of Reelin Suppresses Lipoprotein-Induced Cholesterol Accumulation in Macrophages.

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