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Long non?coding RNA MALAT1 regulates cholesterol accumulation in ox?LDL?induced macrophages via the microRNA?17?5p/ABCA1 axis.

ABSTRACT: 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.

SUBMITTER: Liu L

PROVIDER: S-EPMC7057819 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Long non‑coding RNA MALAT1 regulates cholesterol accumulation in ox‑LDL‑induced macrophages via the microRNA‑17‑5p/ABCA1 axis.

Liu Limin L Tan Lili L Yao Jian J Yang Lin L

Molecular medicine reports 20200213 4

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 lev ...[more]

PMID: 32319624

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Project description:Circulating low-density lipoprotein (LDL) that enters the blood vessel wall is the main source of cholesterol that accumulates within atherosclerotic plaques. Much of the deposited cholesterol accumulates within plaque macrophages converting these macrophages into cholesterol-rich foamy looking cells. Cholesterol accumulation in macrophages contributes to cholesterol retention within the vessel wall, and promotes vessel wall inflammation and thrombogenicity. Thus, how macrophages accumulate cholesterol and become foam cells has been the subject of intense investigation. It is generally believed that macrophages accumulate cholesterol only through scavenger receptor-mediated uptake of modified LDL. However, an alternative mechanism for macrophage foam cell formation that does not depend on LDL modification or macrophage receptors has been elucidated. By this alternative mechanism, macrophages show receptor-independent uptake of unmodified native LDL that is mediated by fluid-phase pinocytosis. In receptor-independent, fluid-phase pinocytosis, macrophages take up LDL as part of the fluid that they ingest during micropinocytosis within small vesicles called micropinosomes, and by macropinocytosis within larger vacuoles called macropinosomes. This produces cholesterol accumulation in macrophages to levels characteristic of macrophage foam cells in atherosclerotic plaques. Fluid-phase pinocytosis of LDL is a plausible mechanism that can explain how macrophages accumulate cholesterol and become disease-causing foam cells. Fluid-phase pinocytosis of LDL is a relevant pathway to target for modulating macrophage cholesterol accumulation in atherosclerosis. Recent studies show that phosphoinositide 3-kinase (PI3K), liver X receptors (LXRs), the macrophage colony-stimulating factor (M-CSF) receptor, and protein kinase C (PKC) mediate macrophage macropinocytosis of LDL, and thus, these may be relevant targets to inhibit macrophage cholesterol accumulation in atherosclerosis.

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Dataset Information

Long non?coding RNA MALAT1 regulates cholesterol accumulation in ox?LDL?induced macrophages via the microRNA?17?5p/ABCA1 axis.

Publications

Long non‑coding RNA MALAT1 regulates cholesterol accumulation in ox‑LDL‑induced macrophages via the microRNA‑17‑5p/ABCA1 axis.

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