[Research advances on the role of ACSL3 in the atherosclerosis].

Lipids droplets are organelles that store neutral lipids and are closely related to lipid accumulation. Long chain acyl-coenzyme A synthetase 3 (ACSL3) is a lipid droplet-associated protein mainly distributed in the cell membrane, endoplasmic reticulum, and intracellular lipid droplets, and its distribution depends on cell type and fatty acid supply. ACSL3 is a key regulator of fatty acid metabolism that is closely related to intracellular lipid accumulation, and plays an important role in various pathophysiological processes such as lipid droplet synthesis and lipid metabolism, cellular inflammation, and ferroptosis. This paper mainly reviews the role of ACSL3 in lipid synthesis, ferroptosis, and inflammatory response, with focus on the mechanism of its role in lipid accumulation in atherosclerosis, and provides new ideas for exploring potential therapeutic targets in atherosclerotic diseases.

[NADPH oxidase activity does not affect cellular cholesterol loading in vascular smooth muscle cells].

Reactive oxygen species generated by NADPH oxidase enhance aortic vascular smooth muscle cell proliferation and migration which play an important role in the pathophysiology of atherosclerosis. We investigated the role of NADPH oxidase in the cellular cholesterol metabolism in vascular smooth muscle cells using p47phox-deficient cells. Wild-type and p47phox knockout vascular smooth muscle cells were loaded with cholesterol for 72 h by using 10 mg/L cholesterol:methyl-beta-cyclodextrin complexes and then incubated with or without 0.3 mg/L thrombin for 10 min. Foam cell formation was determined by accumulation of intracellular cholesterol, oil Red O-stained lipid droplets. After cholesterol loading, cellular lipid droplets raised sharply, cellular cholesterol increased from (31.4+/-2.0) to (61.0+/-2.1) mg/g protein (P<0.05) in wild-type cells, and from (29.8+/-2.5) to (51.3+/-3.1) mg/g protein (P<0.05) in p47phox deficient cells, but the difference between the two cell types was not significant. Immunostaining showed decreased levels of smooth muscle alpha-actin and increased levels of macrophage marker Mac-2 in both wild-type and p47phox deficient vascular smooth muscle cells. One of the macrophage-related inflammation genes, monocyte chemoattractant protein-1 (MCP-1) expression did not change in both two cell types detected by immunostaining. Although additional incubating with thrombin, another macrophage-related inflammation gene, vascular cell adhesion molecule-1 (VCAM-1) expression was similar in all groups analyzed by real-time RT-PCR. However, the expression of ATP-binding cassette transporter A1 (ABCA1), acyl-coenzyme A:cholesterol acyltransferase 1 (ACAT1), the key proteins in cellular cholesterol metabolism, were similarly increased (P<0.05) in both two cell types as determined by quantitative real-time RT-PCR and Western blot, and it was not related to the state of oxidative stress. Interestingly, the expression of adipophilin, the lipid droplet related protein, had the similar results with ABCA1 and ACAT1, but, in wild-type cells, its expression also increased merely incubating with thrombin as determined by quantitative real-time RT-PCR. Together, these results suggest that p47phox-dependent NADPH oxidase is not involved in transdifferentitation of vascular smooth muscle cells into macrophage-like state after cholesterol loading. Deleting p47phox gene does not affect the cellular cholesterol metabolism in vascular smooth muscle cells.

Effect of apolipoprotein A-I on ATP binding cassette transporter A1 degradation and cholesterol efflux in THP-1 macrophage-derived foam cells.

Cholesterol-loaded macrophage foam cells are a central component of atherosclerotic lesions. ATP binding cassette transporter A1 (ABCA1), the defective molecule in Tangier disease, mediates the efflux of phospholipid and cholesterol from cells to apolipoprotein A-I (apoA-I), reversing foam cell formation. This study investigated the effect of apoA-I on ABCA1 degradation and cholesterol efflux in THP-1 macrophage-derived foam cells. After exposure of the cultured THP-1 macrophage-derived foam cells to apoA-I for different time, cholesterol efflux, ABCA1 mRNA and protein levels were determined by FJ-2107P type liquid scintillator, RT-PCR and Western blot, respectively. The mean ABCA1 fluorescence intensity on THP-1 macrophage-derived foam cells was detected by flow cytometry. Results showed that apoA-I markedly increased ABCA1-mediated cholesterol efflux from THP-1 macrophage-derived foam cells. This was accompanied by an increase in the content of ABCA1. ApoA-I did not alter ABCA1 mRNA abundance. Significantly, thiol protease inhibitors increased the level of ABCA1 protein and slowed its decay in THP-1 macrophage-derived foam cells, whereas none of the proteosome-specific inhibitor lactacystin, other protease inhibitors, or the lysosomal inhibitor NH4Cl showed such effects. The apoA-I-mediated cellular cholesterol efflux was enhanced by thiol protease inhibitors. Our results suggested that thiol protease inhibitors might provide an alternative way to upregulate ABCA1 protein. This strategy is especially appealing since it may mimic the stabilizing effect of the natural ligands apoA-I.

[Effects of oleate on ATP binding cassette transporter A1 expression and cholesterol efflux in THP-1 macrophage-derived foam cells].

To study the effect of oleate on ATP binding cassette transporter A1 (ABCA1) expression and cholesterol efflux in THP-1 macrophage-derived foam cells, after exposure of the cultured THP-1 macrophage-derived foam cells to oleate for different time, cholesterol efflux was determined by FJ-2107P type liquid scintillator. ABCA1 mRNA and its protein level were determined by RT-PCR and Western blot, respectively. The mean ABCA1 fluorescence intensity of THP-1 macrophage-derived foam cells was detected by flow cytometry. The results showed that oleate markedly inhibited ABCA1-mediated cholesterol efflux from THP-1 macrophage-derived foam cells. This was accompanied by a reduction in the membrane content of ABCA1. Oleate did not alter ABCA1 mRNA abundance, indicating that decreased ABCA1 transcription, enhanced mRNA decay, or impaired translation efficiency did not account for these inhibitory effects. Oleate, however, increased ABCA1 turnover when protein synthesis was blocked by cycloheximide. Oleate reduces cholesterol efflux and the level of ABCA1 protein in THP-1 macrophage-derived foam cells.