Native LDL Upregulation of ATP-Binding Cassette Transporter-1 in Human Vascular Endothelial Cells

Abstract Background A high level of total cholesterol is associated with several lipid metabolism disorders, including atherosclerosis and cardiovascular diseases. ATP-binding cassette (ABC) transporter A1 (ABCA1) and miR-33-5p play crucial roles in atherosclerosis by controlling cholesterol efflux. While citrate is a precursor metabolite for lipid and cholesterol synthesis, little is known about the association between citrate synthase (CS) and cholesterol efflux. This study investigated the role of the miR-33-5p/ABCA1/CS axis in regulating cholesterol efflux in vascular endothelial cells (VECs). Materials and methods VECs were treated with oxidized low-density lipoprotein cholesterol (ox-LDL), or pretreated with plasmids overexpressing CS, ABCA1, siRNAs against CS and ABCA1, and an miR-33-5p inhibitor. Cell apoptosis, cellular senescence-associated β-galactosidase activity, inflammation, and cholesterol efflux were detected. Results Treatment with ox-LDL decreased ABCA1 and CS levels and increased miR-33-5p expression and apoptosis in dose-dependent manners. In contrast, treatment with the miR-33-5p inhibitor and ABCA1 and CS overexpression plasmids inhibited the above-mentioned ox-LDL-induced changes. In addition, treatment with ox-LDL decreased cholesterol efflux, induced aging, and promoted the production of inflammatory cytokines (i.e., IL-6 and tumor necrosis factor TNF-α), as well as the expression of Bax and Caspase 3 proteins in VECs. All these changes were rescued by miR-33-5p inhibition and ABCA1 and CS overexpression. The inhibition of ABCA1 and CS by siRNAs eliminated the effects mediated by the miR-33-5p inhibitor, and knockdown of CS eliminated the effects of ABCA1 on VECs. Conclusions This study demonstrated the crucial roles played by the miR-33-5p/ABCA1/CS axis in regulating cholesterol efflux, inflammation, apoptosis, and aging in VECs, and also suggested the axis as a target for managing lipid metabolism disorders.

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Human apolipoprotein A-I induces cyclooxygenase-2 expression and prostaglandin I-2 release in endothelial cells through ATP-binding cassette transporter A1

AJP Cell Physiology ◽

10.1152/ajpcell.00055.2011 ◽

2011 ◽

Vol 301 (3) ◽

pp. C739-C748 ◽

Cited By ~ 34

Author(s):

Donghui Liu ◽

Liang Ji ◽

Xunliang Tong ◽

Bing Pan ◽

Jing-Yan Han ◽

...

Keyword(s):

Endothelial Cells ◽

Umbilical Vein ◽

Cyclooxygenase 2 ◽

Mitogen Activated Protein Kinase ◽

Atp Binding ◽

Dependent Manner ◽

Atp Binding Cassette Transporter ◽

Apolipoprotein A ◽

Cox 2 ◽

Atp Binding Cassette

High-density lipoprotein (HDL) can induce cyclooxygenase-2 (COX-2) expression and prostacyclin I-2 (PGI-2) release in endothelial cells to exert multiple antiatherogenic functions. This effect has been attributed mainly to the role of sphingosine-1-phosphate (S1P) integrated in HDL. However, whether apolipoprotein A-I (apoA-I), the major apolipoprotein of HDL, could induce COX-2 expression and PGI-2 release still remains unclear. In the present study, we selectively delipidated HDL and confirmed that apoA-I could facilitate COX-2 expression and PGI-2 production in human umbilical vein endothelial cells (HUVECs). ApoA-I, but not trypsinized apoA-I, induced COX-2 expression in a time- and dose-dependent manner consistent with a key role for apoA-I in this process. Additionally, cotreatment of apoA-I with S1P further enhanced COX-2 expression and PGI-2 production in HUVECs. These effects triggered by apoA-I were not inhibited by pertussis toxin, consistent with SIP receptor independent pathway for apoA-I effect. Moreover, we demonstrated that the activation of p38 mitogen-activated protein kinase (MAPK), extracellular receptor kinase (ERK) 1/2, and JAK2 pathways by apoA-I was involved in the expression of COX-2 and the release of PGI-2 in HUVECs, and these effects were inhibited by their specific inhibitors, respectively. Small interfering RNA experiments showed that ATP binding-cassette transporter A1 (ABCA1) was required for COX-2 expression and PGI-2 release induced by apoA-I. Thus our results indicate that apoA-I induces COX-2 expression and PGI-2 release through ABCA1 and the activation of intracellular p38 MAPK, ERK1/2, as well as JAK2 pathways, and apoA-I can reinforce these effects with S1P in HUVECs. These novel effects of apoA-I could in part mediate antiatherogenic effects of HDL.

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