Summary: To investigate the effects of leptin on expression of acyl-coenzymeA:cholesterol acyltransferases-1 (ACAT-1) in monocyte-macrophage differentiation, human monocytic cells (THP-1) were cultured in RPMI 1640 an...Summary: To investigate the effects of leptin on expression of acyl-coenzymeA:cholesterol acyltransferases-1 (ACAT-1) in monocyte-macrophage differentiation, human monocytic cells (THP-1) were cultured in RPMI 1640 and made to differentiate into macrophages under the incubation with phorbol myristate acetate (PMA) for 48 h. The cells were divided into 4 groups according to different intervention factors as follows: MCs cultured in RPMI1640 medium with 10 % FBS for 48 h served as MC group (control group), MCs cultured in medium with serum-free RPMI1640 containing 5 % BSA, 100 nmol/L PMA for 48 h as MP group, MCs cultured in RPMI1640 medium with 10 % FBS, 10 μmol/ml leptin for 48 h as leptin-MC group, and MCs cultured in medium with serum-free RPMI1640 containing 5 % BSA, 100 nmol/L PMA, and 10 μmol/ml leptin for 48 h as leptin-MP group. Immunocytochemistry, reverse transcription polymerase chain reaction (RT-PCR) and Western blot were performed, respectively, to observe the effects of leptin on expression of ACAT-1 in the monocyte-macrophage differentiation. Our results showed that expression of ACAT-1 protein and mRNA in MP-group is two times that in MC-group (P<0.05), and the expression of ACAT-1 protein and mRNA increased by up to 4 folds in leptin-MP group as compared with that of MC group (P<0.01). Thus, our results support the idea that expression of ACAT-1 increases more in cultured human macrophages than in monocytes, and leptin can significantly promote ACAT-1 expression. It was concluded that high expression of ACAT-1 may accelerate the development of human atherogenesis,and leptin might participate in atherogenesis by increasing expression of ACAT-1.展开更多
Objective To verify the regulation of acyl-coenzyme A:cholesterol acyltransferase 2 (ACAT 2), which is associated with cholesterol metabolism, by saturated fatty acids (SFAs). Methods Palmitic acid (PA), the most abun...Objective To verify the regulation of acyl-coenzyme A:cholesterol acyltransferase 2 (ACAT 2), which is associated with cholesterol metabolism, by saturated fatty acids (SFAs). Methods Palmitic acid (PA), the most abundant saturated fatty acid in plasma, and oleic acid (OA), a widely distributed unsaturated fatty acid, were used to treat hepatic cells HepG2, HuH7, and mouse primary hepatocytes. In addition, PA at different concentrations and PA treatment at different durations were applied in HepG2 cells. In in vivo experiment, three-month male C57/BL6 mice were fed with control diet and SFA diet containing hydrogenated coconut oil rich of SFAs. The mRNA level of ACAT2 in those hepatic cells and the mouse livers was detected with real-time polymerase chain reaction (PCR). Results In the three types of hepatic cells treated with PA, that SFA induced significant increase of ACAT2 expression (P<0.01), whereas treatment with OA showed no significant effect. That effect of PA was noticed gradually rising along with the increase of PA concentration and the extension of PA treatment duration (both P<0.05). SFA diet feeding in mice resulted in a short-term and transient increase of ACAT2 expression in vivo, with a peak level appearing in the mice fed with SFA diet for two days (P<0.05). Conclusion SFA may regulate ACAT2 expression in human and mouse hepatic cells and in mouse livers.展开更多
Objective To investigate the role of acyl-coenzyme A:cholesterol acyltransferase inhibitor(ACATI) in apoptosis induced by lipids and whether lipids-induced apoptosis is accompanied by increase of free cholesterol in e...Objective To investigate the role of acyl-coenzyme A:cholesterol acyltransferase inhibitor(ACATI) in apoptosis induced by lipids and whether lipids-induced apoptosis is accompanied by increase of free cholesterol in endoplasmic reticulum(ER),in order to further understand the mechanism of lipids-induced apoptosis in advanced atherosclerosis.Methods Human vascular smooth muscle cells(VSMCs) and phorbol 12-myristate 13-acetate(PMA) differentiated THP-1 macrophages were used.Tritiated thymidine incorporation was applied to detect cell proliferation.Cytotoxicity was assessed by lactate dehydrogenase(LDH) release.4',6-diamidino-2-phenylindole(DAPI) staining,caspase-3,-7 assay,and Annexin-V/propidium iodide(PI) staining were used to detect apoptosis.High performance liquid chromatography was used in intracellular free cholesterol and cholesterol ester assay.ER free cholesterol was quantified.Results Different lipids had different effects on proliferation and cytotoxicity of VSMCs.25-hydroxycholesterol(25OHC) had biphasic effects on the proliferation of VSMCs.At low concentration,it stimulated cell proliferation,but turned to proliferation inhibition as concentration reached 15 μg/mL.25OHC and acetylated low density lipoprotein(AcLDL) could respectively induce apoptosis in human VSMCs and PMA differentiated THP-1 macrophages,which was aggravated by ACATI,accompanied by increase of intracellular free cholesterol content.There was also an increase of cholesterol content in ER with AcLDL-induced apoptosis in THP-1 macrophages.Conclusions Lipids could induce apoptosis,accompanied by increase of intracellular free cholesterol content,which could be augmented by ACATI,suggesting that insults resulting in ER free cholesterol rise might be the initiator of apoptosis.展开更多
In order to explore the effect and mechanisms of tumor necrosis factor-α （TNF-α） on the activity of the acyl coenzyme A： cholesteryl acyltransferase （ACAT）, THP-I monocytes were cul- tured and induced to differ...In order to explore the effect and mechanisms of tumor necrosis factor-α （TNF-α） on the activity of the acyl coenzyme A： cholesteryl acyltransferase （ACAT）, THP-I monocytes were cul- tured and induced to differentiate into macrophages with phorbol ester. TNF-α （60 ng/mL） was added at different time points into the macrophage-containing medium and the ACAT enzyme activity was measured by quantifying the incorporation of [1-^14C] oleoyl CoA into cholesteryl esters. The expression of ACAT-1 protein and mRNA was respectively detected by Western blotting and RT-PCR in THP-1 macrophages 24 h after treatment with TNF-α （60 ng/mL）. The results indicated that ACAT activity in THP-I macrophages treated with TNF-α was increased in a time-dependent manner. The expression levels of ACAT-1 protein and mRNA were significantly increased in THP-I macrophages after treatment with TNF-α （P〈0.05）. It was suggested that TNF-α could increase the activity of ACAT in THP-1 macrophages by up-regulating the expression of ACAT-1 gene.展开更多
ABSTRACT：Two separate studies tested the hypoth- esis that plasma low-density lipoprotein cholesterol LDL-C ） can be decreased by conjugated linoleic acid （CLA） by depressing hepatic acyl-coenzyme A： cholesterol...ABSTRACT：Two separate studies tested the hypoth- esis that plasma low-density lipoprotein cholesterol LDL-C ） can be decreased by conjugated linoleic acid （CLA） by depressing hepatic acyl-coenzyme A： cholesterol acyltransferase （ACAT） activity. In the first experiment, 3 groups of 6 early-weaned piglets were fed low-fat diets containing either 1.5% CLA, 1.5% corn oil or 1.5% beef tallow;fat provided 8% of the energy intake. In the second experiment, 4 groups of 6 early-weaned piglets were fed high-fat di- ets containing either 15% beef tallow, 12% beef tal- low plus 3% CLA, 15% corn oil, or 12% corn oil plus 3% CLA; fat provided 29% of energy intake. Cholesterol was balanced across diets in both experi-ments. In pigs fed the low-fat diets, all dietary fats in- creased LDL-C and triacylglycerols and decreased high-density lipoprotein cholesterol （ HDL-C ） and very low-density lipoprotein cholesterol （VLDL-C）. LDL-C was the same in pigs fed low-fat tallow or low-fat CLA diets. However, ACAT activity was near- ly 80% higher in pigs fed the low-fat tallow diet than in pigs fed the low-fat CLA diets. All high-fat diets increased LDL-C, HDL-C and triacylglycerols equally with no effect on VLDL-C. There were no unique fat- ty acid effects of the high-fat diets on ACAT activity. We conclude that supplemental fats had differential effects on hepatic ACAT activity and LDL-C, but on- ly in pigs fed low-fat diets.展开更多
The enzymes of the acyl-coenzyme A:cholesterol acyltransferase(ACAT)family are responsible for the in vivo synthesis of neutral lipids.They are potential drug targets for the intervention of atherosclerosis,hyperlipid...The enzymes of the acyl-coenzyme A:cholesterol acyltransferase(ACAT)family are responsible for the in vivo synthesis of neutral lipids.They are potential drug targets for the intervention of atherosclerosis,hyperlipidemia,obesity,type II diabetes and even Alzheimer’s disease.ACAT family enzymes are integral endoplasmic reticulum(ER)membrane proteins and can be divided into ACAT branch and acyl-coenzyme A:diacylglycerol acyltransferase 1(DGAT1)branch according to their substrate specificity.The ACAT branch catalyzes synthesis of cholesteryl esters using long-chain fatty acyl-coenzyme A and cholesterol as substrates,while the DGAT1 branch catalyzes synthesis of triacylglycerols using fatty acylcoenzyme A and diacylglycerol as substrates.In this review,we mainly focus on the recent progress in the structural research of ACAT family enzymes,including their disulfide linkage,membrane topology,subunit interaction and catalysis mechanism.展开更多
Objective: To investigate the mechanism of Astragalus-Angelica Mixture (AAM) ’s effects on lipid metabolism disturbance in nephrotic rats.Methods: To examine the effects of AAM on serum albumin, lipid levels, and act...Objective: To investigate the mechanism of Astragalus-Angelica Mixture (AAM) ’s effects on lipid metabolism disturbance in nephrotic rats.Methods: To examine the effects of AAM on serum albumin, lipid levels, and activities of lipoprotein lipase (LPL) and lecithin-cholesterol acyltransferase (LCAT), which are key enzymes for metabolism of lipid in immune-induced nephrotic hyperlipidemia rats and exogenous hyperlipidemia rats.Results: In nephrotic rats, serum albumin was reduced, lipid increased significantly, LPL activity decreased markedly and the LCAT activity was relatively insufficient. Activities of LPL and LCAT increased obviously in AAM treated nephrotic rats. There were no change of activities of LPL and LCAT in exogenous hyperlipidemia rats and AAM showed no effect on the activities of these two enzymes.Conclusion: The effect of AAM on regulating lipid metabolism might be due to enhance the clearance of both triglyceride-rich and cholesterol-rich apoB containing lipoprotein by improving the activities of LPL and LCAT.展开更多
文摘Summary: To investigate the effects of leptin on expression of acyl-coenzymeA:cholesterol acyltransferases-1 (ACAT-1) in monocyte-macrophage differentiation, human monocytic cells (THP-1) were cultured in RPMI 1640 and made to differentiate into macrophages under the incubation with phorbol myristate acetate (PMA) for 48 h. The cells were divided into 4 groups according to different intervention factors as follows: MCs cultured in RPMI1640 medium with 10 % FBS for 48 h served as MC group (control group), MCs cultured in medium with serum-free RPMI1640 containing 5 % BSA, 100 nmol/L PMA for 48 h as MP group, MCs cultured in RPMI1640 medium with 10 % FBS, 10 μmol/ml leptin for 48 h as leptin-MC group, and MCs cultured in medium with serum-free RPMI1640 containing 5 % BSA, 100 nmol/L PMA, and 10 μmol/ml leptin for 48 h as leptin-MP group. Immunocytochemistry, reverse transcription polymerase chain reaction (RT-PCR) and Western blot were performed, respectively, to observe the effects of leptin on expression of ACAT-1 in the monocyte-macrophage differentiation. Our results showed that expression of ACAT-1 protein and mRNA in MP-group is two times that in MC-group (P<0.05), and the expression of ACAT-1 protein and mRNA increased by up to 4 folds in leptin-MP group as compared with that of MC group (P<0.01). Thus, our results support the idea that expression of ACAT-1 increases more in cultured human macrophages than in monocytes, and leptin can significantly promote ACAT-1 expression. It was concluded that high expression of ACAT-1 may accelerate the development of human atherogenesis,and leptin might participate in atherogenesis by increasing expression of ACAT-1.
基金Supported by National Natural Science Foundation of China (30721063)National High Technology Research and Development Program of China (863 Program) (2006AA02A406)+1 种基金National Basic Research Program of China (973 Program) (2006CB503801)Special Fund of the National Laboratory of China (2060204)
文摘Objective To verify the regulation of acyl-coenzyme A:cholesterol acyltransferase 2 (ACAT 2), which is associated with cholesterol metabolism, by saturated fatty acids (SFAs). Methods Palmitic acid (PA), the most abundant saturated fatty acid in plasma, and oleic acid (OA), a widely distributed unsaturated fatty acid, were used to treat hepatic cells HepG2, HuH7, and mouse primary hepatocytes. In addition, PA at different concentrations and PA treatment at different durations were applied in HepG2 cells. In in vivo experiment, three-month male C57/BL6 mice were fed with control diet and SFA diet containing hydrogenated coconut oil rich of SFAs. The mRNA level of ACAT2 in those hepatic cells and the mouse livers was detected with real-time polymerase chain reaction (PCR). Results In the three types of hepatic cells treated with PA, that SFA induced significant increase of ACAT2 expression (P<0.01), whereas treatment with OA showed no significant effect. That effect of PA was noticed gradually rising along with the increase of PA concentration and the extension of PA treatment duration (both P<0.05). SFA diet feeding in mice resulted in a short-term and transient increase of ACAT2 expression in vivo, with a peak level appearing in the mice fed with SFA diet for two days (P<0.05). Conclusion SFA may regulate ACAT2 expression in human and mouse hepatic cells and in mouse livers.
基金Supported by National Natural Science Foundation of China (30700373)
文摘Objective To investigate the role of acyl-coenzyme A:cholesterol acyltransferase inhibitor(ACATI) in apoptosis induced by lipids and whether lipids-induced apoptosis is accompanied by increase of free cholesterol in endoplasmic reticulum(ER),in order to further understand the mechanism of lipids-induced apoptosis in advanced atherosclerosis.Methods Human vascular smooth muscle cells(VSMCs) and phorbol 12-myristate 13-acetate(PMA) differentiated THP-1 macrophages were used.Tritiated thymidine incorporation was applied to detect cell proliferation.Cytotoxicity was assessed by lactate dehydrogenase(LDH) release.4',6-diamidino-2-phenylindole(DAPI) staining,caspase-3,-7 assay,and Annexin-V/propidium iodide(PI) staining were used to detect apoptosis.High performance liquid chromatography was used in intracellular free cholesterol and cholesterol ester assay.ER free cholesterol was quantified.Results Different lipids had different effects on proliferation and cytotoxicity of VSMCs.25-hydroxycholesterol(25OHC) had biphasic effects on the proliferation of VSMCs.At low concentration,it stimulated cell proliferation,but turned to proliferation inhibition as concentration reached 15 μg/mL.25OHC and acetylated low density lipoprotein(AcLDL) could respectively induce apoptosis in human VSMCs and PMA differentiated THP-1 macrophages,which was aggravated by ACATI,accompanied by increase of intracellular free cholesterol content.There was also an increase of cholesterol content in ER with AcLDL-induced apoptosis in THP-1 macrophages.Conclusions Lipids could induce apoptosis,accompanied by increase of intracellular free cholesterol content,which could be augmented by ACATI,suggesting that insults resulting in ER free cholesterol rise might be the initiator of apoptosis.
基金This project was supported by a grant from the National Natural Sciences Foundation of China (No. 30170378)
文摘In order to explore the effect and mechanisms of tumor necrosis factor-α （TNF-α） on the activity of the acyl coenzyme A： cholesteryl acyltransferase （ACAT）, THP-I monocytes were cul- tured and induced to differentiate into macrophages with phorbol ester. TNF-α （60 ng/mL） was added at different time points into the macrophage-containing medium and the ACAT enzyme activity was measured by quantifying the incorporation of [1-^14C] oleoyl CoA into cholesteryl esters. The expression of ACAT-1 protein and mRNA was respectively detected by Western blotting and RT-PCR in THP-1 macrophages 24 h after treatment with TNF-α （60 ng/mL）. The results indicated that ACAT activity in THP-I macrophages treated with TNF-α was increased in a time-dependent manner. The expression levels of ACAT-1 protein and mRNA were significantly increased in THP-I macrophages after treatment with TNF-α （P〈0.05）. It was suggested that TNF-α could increase the activity of ACAT in THP-1 macrophages by up-regulating the expression of ACAT-1 gene.
基金Supported by USDA/CSREES Competitive Grant 98-35206-6286federal funds from the USDA,ARS under Cooperative Agreement no.58-6250-1-003
文摘ABSTRACT：Two separate studies tested the hypoth- esis that plasma low-density lipoprotein cholesterol LDL-C ） can be decreased by conjugated linoleic acid （CLA） by depressing hepatic acyl-coenzyme A： cholesterol acyltransferase （ACAT） activity. In the first experiment, 3 groups of 6 early-weaned piglets were fed low-fat diets containing either 1.5% CLA, 1.5% corn oil or 1.5% beef tallow;fat provided 8% of the energy intake. In the second experiment, 4 groups of 6 early-weaned piglets were fed high-fat di- ets containing either 15% beef tallow, 12% beef tal- low plus 3% CLA, 15% corn oil, or 12% corn oil plus 3% CLA; fat provided 29% of energy intake. Cholesterol was balanced across diets in both experi-ments. In pigs fed the low-fat diets, all dietary fats in- creased LDL-C and triacylglycerols and decreased high-density lipoprotein cholesterol （ HDL-C ） and very low-density lipoprotein cholesterol （VLDL-C）. LDL-C was the same in pigs fed low-fat tallow or low-fat CLA diets. However, ACAT activity was near- ly 80% higher in pigs fed the low-fat tallow diet than in pigs fed the low-fat CLA diets. All high-fat diets increased LDL-C, HDL-C and triacylglycerols equally with no effect on VLDL-C. There were no unique fat- ty acid effects of the high-fat diets on ACAT activity. We conclude that supplemental fats had differential effects on hepatic ACAT activity and LDL-C, but on- ly in pigs fed low-fat diets.
文摘The enzymes of the acyl-coenzyme A:cholesterol acyltransferase(ACAT)family are responsible for the in vivo synthesis of neutral lipids.They are potential drug targets for the intervention of atherosclerosis,hyperlipidemia,obesity,type II diabetes and even Alzheimer’s disease.ACAT family enzymes are integral endoplasmic reticulum(ER)membrane proteins and can be divided into ACAT branch and acyl-coenzyme A:diacylglycerol acyltransferase 1(DGAT1)branch according to their substrate specificity.The ACAT branch catalyzes synthesis of cholesteryl esters using long-chain fatty acyl-coenzyme A and cholesterol as substrates,while the DGAT1 branch catalyzes synthesis of triacylglycerols using fatty acylcoenzyme A and diacylglycerol as substrates.In this review,we mainly focus on the recent progress in the structural research of ACAT family enzymes,including their disulfide linkage,membrane topology,subunit interaction and catalysis mechanism.
文摘Objective: To investigate the mechanism of Astragalus-Angelica Mixture (AAM) ’s effects on lipid metabolism disturbance in nephrotic rats.Methods: To examine the effects of AAM on serum albumin, lipid levels, and activities of lipoprotein lipase (LPL) and lecithin-cholesterol acyltransferase (LCAT), which are key enzymes for metabolism of lipid in immune-induced nephrotic hyperlipidemia rats and exogenous hyperlipidemia rats.Results: In nephrotic rats, serum albumin was reduced, lipid increased significantly, LPL activity decreased markedly and the LCAT activity was relatively insufficient. Activities of LPL and LCAT increased obviously in AAM treated nephrotic rats. There were no change of activities of LPL and LCAT in exogenous hyperlipidemia rats and AAM showed no effect on the activities of these two enzymes.Conclusion: The effect of AAM on regulating lipid metabolism might be due to enhance the clearance of both triglyceride-rich and cholesterol-rich apoB containing lipoprotein by improving the activities of LPL and LCAT.
