TIGAR mitigates atherosclerosis by promoting cholesterol efflux from macrophages.

BACKGROUND AND AIMS: TP53-induced glycolysis and apoptosis regulator (TIGAR) is now characterized as a fructose-2,6-bisphosphatase to reduce glycolysis and protect against oxidative stress. Recent studies have demonstrated that TIGAR is associated with cardiovascular disease. However, little is known about its role in atherosclerogenesis. In this study, we aimed to investigate the effect of TIGAR on atherosclerosis and explore the underlying molecular mechanism. METHODS: The Gene Expression Omnibus (GEO) datasets were used to analyze the differential expression of relative proteins. THP-1-derived macrophages were used as an in vitro model and apolipoprotein E-deficient (Apoe-/-) mice were used as an in vivo model. [3H] labeled cholesterol was used to assess the capacity of cholesterol efflux and reverse cholesterol transport (RCT). Both qPCR and Western blot were used to evaluate the mRNA and protein expression, respectively. Lentiviral vectors were used to disturb the expression of TIGAR in vitro and in vivo. Oil Red O, hematoxylin-eosin, and Masson staining were performed to evaluate atherosclerotic plaques in Apoe-/- mice fed a Western diet. Conventional assay kits were used to measure the levels of reactive oxygen species (ROS), plasma lipid profiles and 27-hydroxycholesterol (27-HC). RESULTS: Our results showed that TIGAR is increased upon the formation of macrophage foam cells and atherosclerosis. TIGAR knockdown markedly promoted lipid accumulation in macrophages. Silencing of TIGAR impaired cholesterol efflux and down-regulated the expression of ATP-binding cassette transporter A1 (ABCA1) and ABCG1 by interfering with liver X receptor α (LXRα) expression and activity, but did not influence cholesterol uptake by macrophages. Additionally, this inhibitory effect of TIGAR deficiency on cholesterol metabolism was mediated through the ROS/CYP27A1 pathway. In vivo experiments revealed that TIGAR deficiency decreased the levels of ABCA1 and ABCG1 in plaques and aorta and impaired the capacity of RCT, thereby leading to the progression of atherosclerosis in Apoe-/- mice. CONCLUSIONS: TIGAR mitigates the development of atherosclerosis by up-regulating ABCA1 and ABCG1 expression via the ROS/CYP27A1/LXRα pathway.

Long non-coding RNA PCA3 inhibits lipid accumulation and atherosclerosis through the miR-140-5p/RFX7/ABCA1 axis.

OBJECTIVE: The purpose of this study was to explore the role of long noncoding RNA (lncRNA) prostate cancer antigen 3 (PCA3) in atherosclerosis and the underlying mechanism. METHODS: The Gene Expression Omnibus (GEO) datasets were used to divide differentially expressed lncRNAs, microRNAs (miRNAs), and mRNAs. The expression of PCA3, miR-140-5p, RFX7 and ABCA1 were determined by qPCR or Western blot in ox-LDL-treated macrophages. Macrophage lipid accumulation s was evaluated using the Oil Red O staining and high-performance liquid chromatography. Target relationships among PCA3, miR-140-5p, RFX7, and ABCA1 promoter area were validated via dual-luciferase reporter gene assay or chromatin immunoprecipitation assay. The apoE-/- mouse model in vivo was designed to evaluate the effect of PCA3 on the reverse cholesterol transport (RCT) and atherosclerosis. RESULTS: PCA3 was down-regulated in foam cells, whereas miR-140-5p was highly expressed. Overexpression of PCA3 promoted ABCA1-mediated cholesterol efflux and reduced lipid accumulation in macrophages. Besides, RFX7 bound to the ABCA1 promoter and increased ABCA1 expression. Targeted relationships and interactions on the expression between miR-140-5p and PCA3 or RFX7 were elucidated. PCA3 up-regulated ABCA1 expression by binding to miR-140-5p to up-regulate RFX7 and ABCA1 expression in macrophages. PCA3 promoted RCT and impeded the progression of atherosclerosis by sponging miR-140-5p in apoE-/- mice. Meanwhile, miR-140-5p also inhibit ABCA1 expression via downregulation of RFX7 to impede RCT and aggravate atherosclerosis. CONCLUSIONS: lncRNA PCA3 promotes ABCA1-mediated cholesterol efflux to inhibit atherosclerosis through sponging miR-140-5p and up-regulating RFX7.

Astragalin Retards Atherosclerosis by Promoting Cholesterol Efflux and Inhibiting the Inflammatory Response via Upregulating ABCA1 and ABCG1 Expression in Macrophages.

ABSTRACT: Lipid metabolism disorder and inflammatory response are considered to be the major causes of atherosclerogenesis. Astragalin, the most important functional component of flavonoid obtained from persimmon leaves, has the hypolipidemic effects. However, it is unknown, how astragalin protects against atherosclerosis. The aim of this study was to observe the effects of astragalin on cholesterol efflux and inflammatory response and to explore the underlying mechanisms. Our results showed that astragalin upregulated the expression of ATP-binding cassette transporters A1 and G1 (ABCA1 and ABCG1), promoted cholesterol efflux, and suppressed foam cell formation. Inhibition of the PPARγ/LXRα pathway abrogated the promotive effects of astragalin on both transporter expression and cholesterol efflux. In addition, treatment of astragalin markedly decreased the secretion of inflammatory factors, including interleukin 6, monocyte chemotactic protein 1, tumor necrosis factor α, and interleukin 1ß. Mechanistically, astragalin upregulated ABCA1 and ABCG1 expression, which in turn reduced TLR4 surface levels and inhibited NF-κB nuclear translocation. Consistently, astragalin reduced atherosclerotic plaque area in apoE-/- mice. Taken together, these findings suggest that astragalin protects against atherosclerosis by promoting ABCA1- and ABCG1-mediated cholesterol efflux and inhibiting proinflammatory mediator release.

Fargesin alleviates atherosclerosis by promoting reverse cholesterol transport and reducing inflammatory response.

BACKGROUND AND AIMS: Fargesin mainly functions in the improvement of lipid metabolism and the inhibition of inflammation, but the role of fargesin in atherogenesis and the molecular mechanisms have not been defined. We aimed to explore if and how fargesin affects atherosclerosis by regulating lipid metabolism and inflammatory response. METHODS AND RESULTS: ApoE-/- mice were fed a high-fat diet to form atherosclerotic plaques and then administrated with fargesin or saline via gavage. Oil Red O, HE and Masson staining were performed to assess atherosclerostic plaques in apoE-/- mice. [3H] labeled cholesterol was used to detect cholesterol efflux and reverse cholesterol transport (RCT) efficiency. Enzymatic methods were performed to analyze plasma lipid profile in apoE-/- mice. Immunohistochemistry was used to analyze macrophage infiltration. THP-1-derived macrophages were incubated with fargesin or not. Both Western blot and qRT-PCR were applied to detect target gene expression. Oil Red O staining was applied to examine lipid accumulation in THP-1-derived macrophages. ELISA and qRT-PCR were used to examine the levels of inflammatory mediotors. We found that fargesin reduced atherosclerotic lesions by elevating efficiency of RCT and decreasing inflammatory response via upregulation of ABCA1 and ABCG1 expression in apoE-/- mice. Further, fargesin reduced lipid accumulation in THP-1-derived macrophages. Besides, fargesin increased phosphorylation of CEBPα in Ser21 and then upregulated LXRα, ABCA1 and ABCG1 expression in THP-1-derived macrophages. In addition, fargesin could reduce ox-LDL-induced inflammatory response by inactivation of the TLR4/NF-κB pathway. CONCLUSION: These results suggest that fargesin inhibits atherosclerosis by promoting RCT process and reducing inflammatory response via CEBPαS21/LXRα and TLR4/NF-κB pathways, respectively.

CXCL12 promotes atherosclerosis by downregulating ABCA1 expression via the CXCR4/GSK3ß/ß-cateninT120/TCF21 pathway.

CXC chemokine ligand 12 (CXCL12) is a member of the CXC chemokine family and mainly acts on cell chemotaxis. CXCL12 also elicits a proatherogenic role, but the molecular mechanisms have not been fully defined yet. We aimed to reveal if and how CXCL12 promoted atherosclerosis via regulating lipid metabolism. In vitro, our data showed that CXCL12 could reduce ABCA1 expression, and it mediated cholesterol efflux from THP-1-derived macrophages to apoA-I. Data from the luciferase reporter gene and chromatin immunoprecipitation assays revealed that transcription factor 21 (TCF21) stimulated the transcription of ABCA1 via binding to its promoter region, which was repressed by CXCL12. We found that CXCL12 increased the levels of phosphorylated glycogen synthase kinase 3ß (GSK3ß) and the phosphorylation of ß-catenin at the Thr120 position. Inactivation of GSK3ß or ß-catenin increased the expression of TCF21 and ABCA1. Further, knockdown or inhibition of CXC chemokine receptor 4 (CXCR4) blocked the effects of CXCL12 on TCF21 and ABCA1 expression and the phosphorylation of GSK3ß and ß-catenin. In vivo, the overexpression of CXCL12 in Apoe-/- mice via lentivirus enlarged the atherosclerotic lesion area and increased macrophage infiltration in atherosclerotic plaques. We further found that the overexpression of CXCL12 reduced the efficiency of reverse cholesterol transport and plasma HDL-C levels, decreased ABCA1 expression in the aorta and mouse peritoneal macrophages (MPMs), and suppressed cholesterol efflux from MPMs to apoA-I in Apoe-/- mice. Collectively, these findings suggest that CXCL12 interacts with CXCR4 and then activates the GSK-3ß/ß-cateninT120/TCF21 signaling pathway to inhibit ABCA1-dependent cholesterol efflux from macrophages and aggravate atherosclerosis. Targeting CXCL12 may be a novel and promising strategy for the prevention and treatment of atherosclerotic cardiovascular diseases.