ABSTRACT
AIM:To observe the effects of adipose differentiation-related protein ( adipophilin) on the expres-sion of inflammatory factors in RAW264.7 macrophage and to clarify the related mechanism.METHODS:The cell models with high expression and low expression of adipophilin were constructed by transfecting PA317 packaging cells with stable high or low expression adipophilin retroviral vectors into the RAW264.7 cells.The concentrations of IL-6, MCP-1 and TNF-αin the cell culture medium were detected by ELISA.The protein levels of AP-1, p-AP-1, ERK1/2 and p-ERK1/2 were measured by Western blot.The protein levels of adipophilin, p-ERK1/2 and p-AP-1 and the releases of the inflamma-tory factors in the RAW264.7 cells treated with or without ERK1/2 inhibitor PD98059 or AP-1 inhibitor curcumin were de-termined.RESULTS:The RAW264.7 cells with high expression of adipophilin had higher levels of IL-6, MCP-1 and TNF-α, and higher protein levels of p-AP-1 and p-ERK1/2 than those in the cells with low expression of adipophilin. ERK1/2 inhibitor had no significant effect on the expression of adipophilin, but the protein expression of ERK1/2 and AP-1 was significantly inhibited (P<0.05).The administration of AP-1 inhibitor curcumin had no significant effect on the protein expression of adipophilin and ERK1/2, but the protein expression of AP-1 was significantly inhibited (P<0.05). At the same time, the releases of inflammatory factors IL-6, MCP-1 and TNF-αwere significantly decreased.CONCLU-SION:Adipophilin may regulate the expression of inflammatory factors through ERK1/2-AP-1 pathway in RAW264.7 mac-rophages.
ABSTRACT
Tangier disease is caused by mutations in ATP binding cassette transporter A1( ABCA1). ABCA1 interacts with lipid-free apolip oproteins, promoting phospholipid and cholesterol efflux from cells and giving r ise to HDL particles. ABCA1 may act as a phospholipid translocase facilitating p hospholipid binding to apoA-I. ABCA1 gene expression is upregulated in cholester ol-loaded cells as a result of activation of LXR/RXR-mediated gene transcription . LXR and RXR coordinately induce a battery of genes mediating cellular choleste rol efflux, centripetal cholesterol transport, and cholesterol excretion in bile . Small-molecule activators of LXR/RXR or other stimulators of macrophage or int estinal cholesterol efflux hold great promise as future treatments for atheroscl erosis.
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AIM: To study the action of ATP binding cassette transporter(ABC) A 1 on cholesterol efflux in THP-1 macrophage-derived foam cells. METHODS: After exposure of the cultured THP-1 macrophage-derived foam cells to 22(R)-hydroxycholesterol and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) at different concentration for 24 hours, cholesterol efflux and ABCA1 mRNA level were determined by FJ-2107P type liquid scintillator and reverse trancriptase-polymerase chaim reaction(RT-PCR), respectively. RESULTS: Oxidized LDL promoted cholesterol efflux in THP-1 macrophages and 22(R)-hydroxycholesterol increased cholesterol efflux in THP-1 macrophage-derived foam cells in a dose-dependent manner and DIDS inhibited cholesterol efflux in THP-1 macrophage-derived foam cells in a dose-dependent manner. Exposure of the cultured THP-1 macrophage-derived foam cells to 22(R)-hydroxycholesterol and DIDS at different concentration for 24 hours, resulted in increase and decrease in the expression of ABCA1 mRNA in THP-1 macrophage-derived foam cells in a dose-dependent manner, respectively. CONCLUSION: ABCA1 playes an important role in cholesterol efflux in THP-1 macrophage-derived foam cells.
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AIM: To study the effects of apolipoprotein (apo) A-Ⅰon ATP binding cassette transporter A1 (ABCA1) degradation and cholesterol efflux in THP-1 macrophage-derived foam cells. METHODS: After exposure of the cultured THP-1 macrophage-derived foam cells to apolipoprotein A-Ⅰ for different time, cholesterol efflux, ABCA1 mRNA and protein level were determined by liquid scintillation counting, reverse transcriptase-polymerase chain reaction and Western blotting, respectively. The mean ABCA1 fluorescence intensity on THP-1 macrophage-derived foam cells was detected by flow cytometry. RESULTS: 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. 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 NH_4Cl showed such effects. The apoA-Ⅰ mediated cellular cholesterol efflux was enhanced by thiol protease inhibitors. CONCLUSION: 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.
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AIM: To determine the effect of promoting cellular cholesterol efflux on the apoptosis of foam cells derived from monocytes. METHODS: RAW264.7 cells were incubated with 50 mg/L ox-LDL as a foam cell mode. The apoptosis rate of RAW264.7 cells was assayed by flow cytometry. Cellular lipid droplet was assayed by oil red staining. The rate of cellular cholesterol efflux was assayed with [~3H] label cholesterol, and the content of cellular cholesterol were assayed by high performance liquid chromatography. RESULTS: After incubation with 50 mg/L ox-LDL for 48 h, the content of cellular cholesterol ester increased from (6.8?3.6) mg/g to (101.7?4.5) mg/g (P
ABSTRACT
AIM: Based on the finding of adipophilin expression with the increase in cellular cholesterol, the aim of the present study was to look for the active site of adipophilin in cellular cholesteryl metabolism. METHODS: Mouse peritoneal macrophages were incubated with 80 mg/L Ox-LDL (Ox-LDL group) or 80 mg/L Ox-LDL plus 1 mmol/L adipophilin antisense oligonucleotides (Ox-LDL+antisense group), respectively. At the various time points, the incubated cell samples were observed with adipophilin immunofluorescence staining, flow cytometric analysis and cellular cholesterol analysis. RESULTS: The Ox-LDL+antisense group cells contained significantly lower cholesteryl ester (19.9?1.9) mg/g (protein) than that of cells in Ox-LDL group (46.6?3.4) mg/g (protein) at 4 days. From 12 h, expression of adipophilin in Ox-LDL group increased more quickly than that of the cells in Ox-LDL+antisense group. At day 4, the level of adipophilin expression in Ox-LDL group was significantly higher than that in Ox-LDL+antisense group. During the observation, the amount of Ox-r[CL-3H] LDL taking up increased gradually in both groups, however, from day 1 the taking up amount in Ox-LDL+antisense group was less than that in Ox-LDL group. There was a statistical difference between the two groups from day 2 to day 4. From 6 h to day 2, the relative ACAT activity increased in both groups. The relative ACAT activity kept unchanged from day 2 to day 4 in the two groups. At day 2, the relative ACAT activity in Ox-LDL+antisense group was significantly lower than that in Ox-LDL group. Correlative analysis between activity of ACAT and adipophilin expression showed than R2 were 0.6176 and 0.8212 (P
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AIM: Anti-atherosclerosis effects of Momordica charantia L was further studied in a New Zealand rabbit atherosclerotic model at the basis of anti-inflammation and antioxidant effects. METHODS: Animals were divided into 3 groups: normal group (normal rabbit diet), atherosclerosis group(diet containing 2% cholesterol), and Momordica charantia L group(diet containing 2% cholesterol and 1 5% sarcocarp of Momordica charantia L ). Ninety days later, all animals were sacrificed. The effect of Momordica charantia L on atherosclerosis was evaluated by measuring serum lipid and total cholesterol content of artery wall, observing fatty liver degree, aorta arteriosclerotic area, and the thickness of intima. RESULTS: The level of total serum cholesterol and LDL-C in Momordica charantia L treatment group were obviously lower than those in atherosclerosis group, so were the total cholesterol content of artery wall, fatty liver degree, atherosclerotic area, intima thickness and I/M ratio, but no significantly difference was found between the two groups in TG level. The level of HDL-C in Momordica charantia L treatment group was evidently lower than that in normal control group. CONCLUSION: Momordica charantia L has an anti-atherosclerosis action in rabbits.
ABSTRACT
Niemann-pick protein C1(NPC1) is a large integral membrane glycoprotein that resides in late endosomes,whereas niemann-pick protein C2(NPC2) is a small soluble protein found in the lumen of lysosomes.NPC1 protein is believed to facilitate the transport of lipids,particularly cholesterol,from late endosomes/lysosomes to the Golgi apparatus,endoplasmic reticulum and plasma membrane.NPC2 primarily plays a role in the egress of cholesterol and glycolipids from lysosomes.Mutations in either NPC1 or NPC2 result in aberrant lipid transport from endocytic compartments,which results in lysosomal storage of a complex mixture of lipids,primarily cholesterol and glycosphingolipids.The NPC proteins regulate sterol homeostasis through production of LDL cholesterol-derived oxysterols.Oxysterols are endogenous ligands for the liver X receptors(LXRs),which can upregulate ATP binding cassette transporter A1(ABCA1) expression.ABCA1 may have antiatherogenic effects through the efflux of it-mediated cholesterol.Meanwhile,NPC1 heterozygote mutation confers substantial resistance to lesional necrosis and lesional macrophage apoptosis.Study of the NPC proteins will help us for further understanding of the mechanisms involved in atherogenesis.