共查询到20条相似文献,搜索用时 15 毫秒
1.
Luís M. B. B. Estronca Hugo A. L. Filipe Armindo Salvador Maria Jo?o Moreno Winchil L. C. Vaz 《Journal of lipid research》2014,55(6):1033-1043
The rate of noncatalyzed transfer of cholesterol (Chol) among lipoproteins and cells in the blood is of fundamental importance as a baseline to assess the role of active transport mechanisms, but remains unknown. Here we address this gap by characterizing the association of the Chol analog, ergosta-5,7,9(11),22-tetraen-3β-ol (DHE), with the lipoproteins VLDL, LDL, HDL2, and HDL3. Combining these results with data for the association of DHE with liposomes, we elaborated a kinetic model for the noncatalyzed exchange of free Chol among blood compartments. The computational results are in good agreement with experimental values. The small deviations are explained by the nonequilibrium distribution of unesterified Chol in vivo, due to esterification and entry of new unesterified Chol, and eventual effects introduced by incubations at low temperatures. The kinetic profile of the homeostasis of unesterified Chol in the blood predicted by the model developed in this work is in good agreement with the observations in vivo, highlighting the importance of passive processes. 相似文献
2.
Castro-Perez J Briand F Gagen K Wang SP Chen Y McLaren DG Shah V Vreeken RJ Hankemeier T Sulpice T Roddy TP Hubbard BK Johns DG 《Journal of lipid research》2011,52(11):1965-1973
Cholesteryl ester transfer protein (CETP) transfers cholesteryl ester (CE) and triglyceride between HDL and apoB-containing lipoproteins. Anacetrapib (ANA), a reversible inhibitor of CETP, raises HDL cholesterol (HDL-C) and lowers LDL cholesterol in dyslipidemic patients; however, the effects of ANA on cholesterol/lipoprotein metabolism in a dyslipidemic hamster model have not been demonstrated. To test whether ANA (60 mg/kg/day, 2 weeks) promoted reverse cholesterol transport (RCT), 3H-cholesterol-loaded macrophages were injected and (3)H-tracer levels were measured in HDL, liver, and feces. Compared to controls, ANA inhibited CETP (94%) and increased HDL-C (47%). 3H-tracer in HDL increased by 69% in hamsters treated with ANA, suggesting increased cholesterol efflux from macrophages to HDL. 3H-tracer in fecal cholesterol and bile acids increased by 90% and 57%, respectively, indicating increased macrophage-to-feces RCT. Mass spectrometry analysis of HDL from ANA-treated hamsters revealed an increase in free unlabeled cholesterol and CE. Furthermore, bulk cholesterol and cholic acid were increased in feces from ANA-treated hamsters. Using two independent approaches to assess cholesterol metabolism, the current study demonstrates that CETP inhibition with ANA promotes macrophage-to-feces RCT and results in increased fecal cholesterol/bile acid excretion, further supporting its development as a novel lipid therapy for the treatment of dyslipidemia and atherosclerotic vascular disease. 相似文献
3.
Neyer J Espinoza C Luppen L Dohety TM Tripathi SC Uzui H Tripathi PV Lee G Shah PK Rajavashisth TB 《Journal of lipid research》2005,46(8):1786-1795
We compared two HPLC methods (anion exchange [AE] and steric exclusion [SE]) for analysis of mouse lipoprotein profiles by determining coefficients of variability (CVs) under varying conditions. CVs for AE and SE were comparable on fresh samples. There was an inverse relationship between subfraction curve area and CV [r = -0.65 (AE) and -0.50 (SE)], consistent with the interpretation that as curve area decreased, error variance increased and signal-to-noise ratio decreased. Sample storage did not affect SE. In contrast, with AE, alterations in measured lipoproteins were apparent after storage, including a decrease in the HDL subfraction [66.8% (baseline) vs. 15.9% (1 week); P < 0.01] and an increase in areas under LDL and VLDL peaks. Concomitant with decreasing HDL area, reproducibility deteriorated with the duration of storage. Analysis of the effects of decreasing sample injectate volume to <25 microl on SE lipoprotein subfractions revealed that areas under LDL and VLDL peaks decreased and persisted as volume was decreased further. Areas under all lipoprotein subfractions measured with either AE or SE were linearly correlated with the amount of cholesterol [r = 0.69 (AE) and 0.87 (SE)]. Both AE and SE yield reproducible, accurate, and rapid measurements of lipoproteins from small amounts of serum. AE yields more sensitive, high-amplitude, well-defined peaks that can be easily distinguished and necessitates the use of smaller sample volumes compared with SE, but sample storage causes alterations in the chromatogram. SE appears better suited to serial analyses involving stored samples. 相似文献
4.
Ruel IL Couture P Cohn JS Bensadoun A Marcil M Lamarche B 《Journal of lipid research》2004,45(8):1528-1537
The aim of the present study was to characterize the composition and metabolism of HDL in subjects with complete hepatic lipase (HL) deficiency. Analyses were carried out in three complete and three partial HL-deficient subjects as well as in eight normotriglyceridemic (NTG) and two hypertriglyceridemic controls. Complete HL deficiency was associated with hypertriglyceridemia and with a 3.5-fold increase in HDL-triglyceride (TG) levels. The in vivo kinetics of apolipoprotein A-I (apoA-I) and apoA-II (d < 1.25 g/l) were studied in the fasted state using a primed-constant infusion of l-(5,5,5-D3)leucine for 12 h. Complete HL deficiency was associated with a reduced fractional catabolic rate of apoA-I in the HL-deficient female proband (-47%) and in her two brothers (-21%) compared with gender- and TG-matched controls. Total plasma and HDL from complete HL-deficient patients were able to mediate normal cholesterol efflux from human skin fibroblasts labeled with [3H]cholesterol. Complete HL deficiency was also associated with normal levels of prebeta-migrating apoA-I-containing HDL separated by two-dimensional gel electrophoresis and with an accumulation of large HDL particles compared with NTG controls. These results suggest that HL activity is important for adequate HDL metabolism, although its presence may not be necessary for normal HDL-mediated reverse cholesterol transport. 相似文献
5.
Malik P Berisha SZ Santore J Agatisa-Boyle C Brubaker G Smith JD 《Journal of lipid research》2011,52(5):951-957
Inflammation has been proposed to impair HDL function and reverse cholesterol transport (RCT). We investigated the effects of inflammation mediated by zymosan, a yeast glucan, on multiple steps along the RCT pathway in vivo and ex vivo. Acute inflammation with 70 mg/kg zymosan impaired RCT to plasma, liver, and feces similarly by 17-22% (P < 0.05), with no additional block at the liver. Hepatic gene expression further demonstrated no change in ABCG5, ABCB4, and ABCB11 expression but a decline in ABCG8 mRNA (32% P < 0.05). Plasma from zymosan-treated mice had a 21% decrease in cholesterol acceptor ability (P < 0.01) and a 35% decrease in ABCA1-specific efflux capacity (P < 0.01) in vitro. Zymosan treatment also decreased HDL levels and led to HDL remodeling with increased incorporation of serum amyloid A. In addition, cholesterol efflux from cultured macrophages declined with zymosan treatment in a dose dependent manner. Taken together, our results suggest that zymosan impairs in vivo RCT primarily by decreasing macrophage-derived cholesterol entering the plasma, with minimal additional blocks downstream. Our study supports the notion that RCT impairment is one of the mechanisms for the increased atherosclerotic burden observed in inflammatory conditions. 相似文献
6.
Orsoni A Villard EF Bruckert E Robillard P Carrie A Bonnefont-Rousselot D Chapman MJ Dallinga-Thie GM Le Goff W Guerin M 《Journal of lipid research》2012,53(4):767-775
In familial hypercholesterolemia (FH), low HDL cholesterol (HDL-C) levels are associated with functional alterations of HDL particles that reduce their capacity to mediate the reverse cholesterol transport (RCT) pathway. The objective of this study was to evaluate the consequences of LDL apheresis on the efficacy of the RCT pathway in FH patients. LDL apheresis markedly reduced abnormal accelerated cholesteryl ester transfer protein (CETP)-mediated cholesteryl ester (CE) transfer from HDL to LDL, thus reducing their CE content. Equally, we observed a major decrease (-53%; P < 0.0001) in pre-β1-HDL levels. The capacity of whole plasma to mediate free cholesterol efflux from human macrophages was reduced (-15%; P < 0.02) following LDL apheresis. Such reduction resulted from a marked decrease in the ABCA1-dependent efflux (-71%; P < 0.0001) in the scavenger receptor class B type I-dependent efflux (-21%; P < 0.0001) and in the ABCG1-dependent pathway (-15%; P < 0.04). However, HDL particles isolated from FH patients before and after LDL apheresis displayed a similar capacity to mediate cellular free cholesterol efflux or to deliver CE to hepatic cells. We demonstrate that rapid removal of circulating lipoprotein particles by LDL apheresis transitorily reduces RCT. However, LDL apheresis is without impact on the intrinsic ability of HDL particles to promote either cellular free cholesterol efflux from macrophages or to deliver CE to hepatic cells. 相似文献
7.
Brodeur MR Brissette L Falstrault L Moreau R 《Journal of cellular biochemistry》2008,105(6):1374-1385
Oxidized low density lipoproteins (OxLDL) are known to promote atherosclerosis, but it is only recently that OxLDL have been associated with alterations of the functions of bone-forming osteoblasts and osteoporosis. Although high density lipoproteins (HDL) are recognized for their anti-atherogenic action, there is less information about their ability to protect against osteoporosis. Therefore, we investigated the capacity of HDL3 to prevent the cell death induced by OxLDL in human osteoblastic cells. Simultaneous exposure of the cells to HDL3 and OxLDL abolished the reduction of cell viability monitored by MTT activity measurement and the induction of apoptosis determined by annexin V staining indicating that HDL3 prevent the apoptosis of osteoblasts induced by OxLDL. This protection correlated with the displacement by HDL3 of OxLDL association to osteoblasts, signifying that OxLDL binding and/or internalization are/is necessary for their cytotoxic effects. We also found that exposition of osteoblastic cells to HDL3 prior to incubation with OxLDL reduced cell death and preserved the lysosomal integrity. This protection was correlated with an increase of SR-BI expression, a modification of OxLDL metabolism with less global uptake of OxLDL and greater selective uptake of cholesterol from OxLDL. These results strongly suggest that, as for atherosclerosis, HDL may exert beneficial actions on bone metabolism. 相似文献
8.
Xiaohu Mei Mingjing Liu Haya Herscovitz David Atkinson 《Journal of lipid research》2016,57(8):1507-1517
apoA-I plays important structural and functional roles in reverse cholesterol transport. We have described the molecular structure of the N-terminal domain, Δ(185-243) by X-ray crystallography. To understand the role of the C-terminal domain, constructs with sequential elongation of Δ(185-243), by increments of 11-residue sequence repeats were studied and compared with Δ(185-243) and WT apoA-I. Constructs up to residue 230 showed progressively decreased percent α-helix with similar numbers of helical residues, similar detergent and lipid binding affinity, and exposed hydrophobic surface. These observations suggest that the C-terminal domain is unstructured with the exception of the last 11-residue repeat (H10B). Similar monomer-dimer equilibrium suggests that the H10B region is responsible for nonspecific aggregation. Cholesterol efflux progressively increased with elongation up to ∼60% of full-length apoA-I in the absence of the H10B. In summary, the sequential repeats in the C-terminal domain are probably unstructured with the exception of H10B. This segment appears to be responsible for initiation of lipid binding and aggregation, as well as cholesterol efflux, and thus plays a vital role during HDL formation. Based on these observations and the Δ(185-243) crystal structure, we propose a lipid-free apoA-I structural model in solution and update the mechanism of HDL biogenesis. 相似文献
9.
Lee-Rueckert M Vikstedt R Metso J Jauhiainen M Kovanen PT 《Journal of lipid research》2008,49(2):358-368
Human atherosclerotic intima contains mast cells that secrete the neutral protease chymase into the intimal fluid, which also contains HDL-modifying proteins, such as cholesteryl ester transfer protein (CETP), in addition to abundant amounts of nascent discoidal HDL particles. Here, we studied chymase-dependent degradation of a) CETP isolated from human plasma and b) CETP-HDL complexes as well as the functional consequences of such degradations. Incubation with chymase caused a rapid cleavage of CETP, yielding a specific proteolytic pattern with a concomitant reduction in its cholesteryl ester transfer activity. These chymase-dependent effects were attenuated after CETP was complexed with HDL. This attenuation was more effective when CETP was complexed with HDL(3) and HDL(2) than with discoidal reconstituted high density lipoprotein (rHDL). Conversely, rHDL, but not spherical HDLs, was protected in such CETP complexes against functional inactivation by chymase. Thus, in contrast to the complexes of CETP with spherical HDLs, the ability of the CETP-rHDL complexes to promote cholesterol efflux from macrophage foam cells remained unchanged, despite treatment with chymase. In summary, complexation of CETP and HDL modifies their resistance to proteolytic inactivation: spherical HDLs protect CETP, and CETP protects discoidal HDL. These results suggest that in inflamed atherosclerotic intima, CETP, via its complexation with HDL, has a novel protective role in early steps of reverse cholesterol transport. 相似文献
10.
Asztalos BF Horvath KV Kajinami K Nartsupha C Cox CE Batista M Schaefer EJ Inazu A Mabuchi H 《Journal of lipid research》2004,45(3):448-455
Our purpose was to compare HDL subpopulations, as determined by nondenaturing two-dimensional gel electrophoresis followed by immunoblotting for apolipoprotein A-I (apoA-I), apoA-II, apoA-IV, apoCs, and apoE in heterozygous, compound heterozygous, and homozygous subjects for cholesteryl ester transfer protein (CETP) deficiency and controls. Heterozygotes, compound heterozygotes, and homozygotes had CETP masses that were 30, 63, and more than 90% lower and HDL-cholesterol values that were 64, 168, and 203% higher than those in controls, respectively. Heterozygotes had approximately 50% lower pre-beta-1 and more than 2-fold higher levels of alpha-1 and pre-alpha-1 particles than controls. Three of the five heterozygotes' alpha-1 particles also contained apoA-II, which was not seen in controls. Compound heterozygotes and homozygotes had very large particles not observed in controls and heterozygotes. These particles contained apoA-I, apoA-II, apoCs, and apoE. However, these subjects did not have decreased pre-beta-1 levels. Our data indicate that CETP deficiency results in the formation of very large HDL particles containing all of the major HDL apolipoproteins except for apoA-IV. We hypothesize that the HDL subpopulation profile of heterozygous CETP-deficient patients, especially those with high levels of alpha-1 containing apoA-I but no apoA-II, represent an improved anti-atherogenic state, although this might not be the case for compound heterozygotes and homozygotes with very large, undifferentiated HDL particles. 相似文献
11.
This paper examines the distribution and prevalence of risk factors for coronary heart disease in a sample of 165 men and 202 women over 40 years of age who had earlier participated in a coronary prevention trial from a general practice in Cambridge, UK. No significant differences were observed in total cholesterol levels between men and women, and a quarter of the sample had concentrations above 6.5 mmol/l which is 250 mg/dl. There were significant sex differences in a number of risk factors with males having significantly higher prevalence of low high density lipoprotein, systolic and diastolic blood pressures, obesity, and smoking than women. About 8% of men and women were obese (as defined by a body mass index > 30), while 47% of men and 35% of women were mildly overweight (body mass index > 25). Two or more risk factors for coronary heart disease (high total cholesterol and/or hypertension and/or obesity) were present in 4% and 9% of older men and women respectively. Furthermore, about half the subjects had more than one risk factor for coronary heart disease. 相似文献
12.
Scott T. Cooper Robert J. Aiello William J. Checovichl Alan D. Attie 《Molecular and cellular biochemistry》1992,113(2):133-140
We previously described a strain of spontaneously hypercholesterolemic pigs carrying an apo-B allele termed Lpb
5. Lpb
5 pigs are heterogeneous with respect to the severity of their hypercholesterolemia. We have termed Lpb
5 pigs with severe hypercholesterolemia Lpb 5.1 pigs, and those with moderate hypercholesterolemia Lpb 5.2, Lpb 5.1 animals have a dramatic increase in buoyant LDL relative to dense LDL, with a buoyant-to-dense LDL ratio of 2.2. In contrast, Lpb 5.2 and control pigs have buoyant-to-dense LDL ratios of 0.7 and 0.5 respectively. This ratio appears to be a stable characteristic of the Lpb 5.1 phenotype because sexually mature boars have a dramatic decrease in total plasma cholesterol concentration with no decrease in their ratio of buoyant-to-dense LDL. We have previously demonstrated a fourteen-fold overproduction of buoyant LDL in the Lpb 5.1 pigs, with very little conversion of dense LDL to buoyant LDL. In the current work, very low density lipoprotein (VLDL) turnover experiments were conducted to determine whether VLDL conversion to buoyant LDL was increased in the Lpb 5.1 pigs. VLDL conversion to buoyant LDL could not account for the increased production of buoyant LDL in Lpb 5.1 pigs. Thus, we cannot account for the increased production of buoyant LDL in the Lpb 5.1 pigs from any measurable plasma lipoprotein source. We have therefore termed this production of buoyant LDL in the Lpb 5.1 pigs direct buoyant LDL production. 相似文献
13.
Rachel J. Brace Brie Sorrenson Dmitri Sviridov Sally P. A. McCormick 《Journal of lipid research》2010,51(11):3370-3376
We present here a gel-based method for rapid purification of apolipoprotein A-I (apoA-I) from small volumes of human plasma. After isolation of high density lipoprotein from plasma, the apoA-I protein was separated by electrophoresis and the apoA-I band excised from the gel. The apoA-I was then eluted from the gel strip, concentrated, and delipidated ready for use. The structure and function of the gel-purified apoA-I protein was compared against apoA-I purified by the traditional size-exclusion chromatography method. The α-helical content of the gel-purified apoA-I as determined by circular dichroism was similar to chromatography-purified apoA-I. The functional activity of gel-purified apoA-I, as determined by cholesterol efflux assays in primary human fibroblasts and RAW264.7 macrophages, was also comparable with chromatography-purified apoA-I. This method is a valid alternative for apoA-I purification with some advantages over traditional chromatography purification including a much reduced plasma volume requirement, less time and cost, and a higher percentage protein recovery. The method is particularly suitable for applications requiring the purification of apoA-I from multiple human or animal samples of interest. 相似文献
14.
高密度脂蛋白(HDL)生物合成是一个有多种膜蛋白和胞质蛋白参与的复杂过程,载脂蛋白A-Ⅰ(apoA-Ⅰ)是HDL中最主要的结构和功能蛋白,它能活化卵磷脂胆固醇脂酰基转移酶(LCAT),贫脂apoA-Ⅰ也是巨噬细胞中三磷酸腺苷结合盒转运体A1(ABCA1)介导的胆固醇流出的重要接受体.因此,apoA-Ⅰ在HDL及胆固醇代谢中的作用至关重要,它赋予了HDL多种抗动脉粥样硬化活性.本文主要就HDL生物合成及apoA-Ⅰ在其中的作用作一综述,以期为揭示HDL的代谢机制提供新思路. 相似文献
15.
16.
Lars Bertilsson Hans Elwing Bo Liedberg Olle Larm Johan Risenfeld Elisabeth Scholander 《Molecular Engineering》1991,1(1):49-57
Surface modification to provide, e.g., a biocompatible surface is an important molecular engineering method. As an example the FTIR-Attenuated Total Reflection (ATR) method has been applied to follow the different steps in the immobilization process of heparin on polyethylene (PE). This chemical multicomponent modification process is based on van der Waals and electrostatic interaction between alternating layers of cross-linked polyethylene imine and dextran sulfate, and finally covalent attachment of partly nitrous acid degraded heparin. Modified PE sheets were withdrawn and analyzed after each reaction step in the process. The overall spectral agreement between the ATR spectra and the spectra obtained from the pure substances used is good, except for slight changes in position and relative intensities of the sulfate and amino peaks. This observation indicates that the amino and sulfate groups are important (electrostatic) binding sites between the alternating polyethylene imine and dextran sulfate layers. The amount of covalently attached heparin was determined according to the thin film model by Harrick. The surface concentration, , falls typically in the range of 2.4–2.7 g/cm2, which is in good agreement with the result from a chemical analysis. The choice of peak areas used in the calculation of is also discussed. 相似文献
17.
Careskey HE Davis RA Alborn WE Troutt JS Cao G Konrad RJ 《Journal of lipid research》2008,49(2):394-398
Proprotein convertase subtilisin/kexin type 9 (PCSK9) has gained attention as a key regulator of serum low density lipoprotein cholesterol (LDL-C) levels. This novel protease causes the degradation of hepatic low density lipoprotein receptors. In humans, gain-of-function mutations in PCSK9 cause a form of familial hypercholesterolemia, whereas loss-of-function mutations result in significantly decreased LDL-C levels and cardiovascular risk. Previous studies have demonstrated that statins upregulate PCSK9 mRNA expression in cultured cells and animal models. In light of these observations, we studied the effect of atorvastatin on circulating PCSK9 protein levels in humans using a sandwich ELISA to quantitate serum PCSK9 levels in patients treated with atorvastatin or placebo for 16 weeks. We observed that atorvastatin (40 mg/day) significantly increased circulating PCSK9 levels by 34% compared with baseline and placebo and decreased LDL-C levels by 42%. These results suggest that the addition of a PCSK9 inhibitor to statin therapy may result in even further LDL-C decreases. 相似文献
18.
以THP-1巨噬细胞源性泡沫细胞为研究对象,观察肝X受体α(LXRα)在THP-1巨噬细胞源性泡沫细胞胆固醇流出中的调控作用.结果发现,22(R)-羟基胆固醇剂量依赖性增加THP-1巨噬细胞源性泡沫细胞胆固醇流出, 而DIDS剂量依赖性减少THP-1巨噬细胞源性泡沫细胞胆固醇流出.逆转录聚合酶链反应显示, 22(R)-羟基胆固醇可增加THP-1巨噬细胞源性泡沫细胞LXRα mRNA的表达, DIDS可抑制THP-1巨噬细胞源性泡沫细胞LXRα mRNA的表达.结果提示,LXRα在巨噬细胞源性泡沫细胞胆固醇流出中起着重要的调控作用,这为开发和寻找抗动脉粥样硬化药物提供了新的思路. 相似文献
19.
Nofer JR Remaley AT Feuerborn R Wolinnska I Engel T von Eckardstein A Assmann G 《Journal of lipid research》2006,47(4):794-803
It has been suggested that the signal transduction initiated by apolipoprotein A-I (apoA-I) activates key proteins involved in cholesterol efflux. ABCA1 serves as a binding partner for apoA-I, but its participation in apoA-I-induced signaling remains uncertain. We show that the exposure of human fibroblasts to ABCA1 ligands (apolipoproteins and amphipathic helical peptides) results in the generation of intracellular signals, including activation of the small G-protein Cdc42, protein kinases (PAK-1 and p54JNK), and actin polymerization. ApoA-I-induced signaling was abrogated by glyburide, an inhibitor of the ABC transporter family, and in fibroblasts from patients with Tangier disease, which do not express ABCA1. Conversely, induction of ABCA1 expression with the liver X receptor agonist, T0901317, and the retinoid X receptor agonist, R0264456, potentiated apoA-I-induced signaling. Similar effects were observed in HEK293 cells overexpressing ABCA1-green fluorescent protein (GFP) fusion protein, but not ABCA1-GFP (K939M), which fails to hydrolyze ATP, or a nonfunctional ABCA1-GFP with a truncated C terminus. We further found that Cdc42 coimmunoprecipitates with ABCA1 in ABCA1-GFP-expressing HEK293 cells exposed to apoA-I but not in cells expressing ABCA1 mutants. We conclude that ABCA1 transduces signals from apoA-I by complexing and activating Cdc42 and downstream kinases and, therefore, acts as a full apoA-I receptor. 相似文献
20.