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1.
LDL受体对清道夫受体活性的影响 总被引:1,自引:0,他引:1
应用经PMA诱导衍生的THP-1巨噬细胞为模型,以单克隆抗体C7B封闭oxLDL上的LDL受体结合位点,结果发现,正常细胞在摄取oxLDL时LDL受体与清道夫受体起协同作用;但C7B作用于蓄积了脂质的THP-1巨噬细胞时,对细胞脂质蓄积程度无明显影响,清道夫受体活性不但不降低反而有所升高,说明由于脂质蓄积LDL受体的作用减弱。 相似文献
2.
蛋白激酶C抑制剂对U937细胞清道夫受体功能的影响 总被引:8,自引:0,他引:8
为了解细胞内蛋白质磷酸化水平对清道夫受体功能的影响,用蛋白激酶C抑掉剂形孢菌素(staurosporine,STA)处理人U937细胞,分别测定对照组和处理组细胞对碘标记的氧化低密度脂蛋白(^125I)ox-LDL的降解,结合,细胞表面受体复合物的内移以及细胞内脂质蓄积的程度,并利用放射自显影方法观察药物对细胞表面受体表达的影响,结果发现STA可以促进细胞结合(^125I)ox-LDL增加细胞表面 相似文献
3.
研究了氧化修饰极低密度脂蛋白(ox-VLDL)对小白鼠腹腔巨噬细胞内脂质堆积作用及其机制。经Cu~(2+)修饰后VLDL的电泳迁移率及脂质过氧化物含量均显著增加。ox-VLDL更易导致小鼠腹腔巨噬细胞内脂质堆积。以相同浓度(300μgTG/mL)或不同浓度(200─500μgTG/mL)的ox-VLDL及正常VLDL(n-VLDL)与巨噬细胞温育24h,前者使巨噬细胞内TG堆积均比后者显著(P<0.01)。同时,随ox-VLDL的脂质过氧化物含量(TBARS水平)增加,巨噬细胞内TG含量的百分率相应增加。以50μg蛋白/mL的n-LDL,ox-LDL,n-VLDL及ox-VLDL与巨噬细胞温育60h。细胞内CE堆积中氧化组均比正常组高(P<0.01)。巨噬细胞对~(125)I-n-VLDL与~(125)I-ox-VLDL的结合、降曲线均有饱和趋势。两结合曲线无明显差异,但细胞对后者降解的量比前者多。结合的竞争实验表明,n-VLDL能抑制大部分~(125)I-ox-VLDL与细胞结合,而Ac-LDL只能抑制小部分。结果表明ox-VLDL主要通过受体途径:大部分经过n-VLDL受体,小部分经过清道夫受体被巨噬细胞摄 相似文献
4.
汪浩川等研究表明一定量Ox-LDL能刺激培养人动脉SMC细胞的增殖[1],Dejager等采用交叉抑制实验证明兔SMC细胞膜上有能结合Ox-LDL的清道夫受体[2],因此Ox-LDL诱导培养人SMC细胞增殖可能是Ox-LDL作用于SMC膜清道夫受体后... 相似文献
5.
用未标记氧化修饰极低密度脂蛋白(ox-VLDL)、n-VLDL、乙酰LDL竞争125I-ox-VLDL与巨噬细胞的结合。在浓度为200μg蛋白/ml时,分别抑制标记ox-VLDL结合量的70~78%、60~70%和25~35%。用未标记ox-VLDL竟争125I-n-VLDL与巨噬细胞的结合,能抑制77%。结果说明ox-VLDL主要通过n-VLDL受体进入巨噬细胞。以ox-VLDL与ox-LDL进行交叉竞争时,ox-VLDL与ox-LDL自身可抑制标记ox-VLDL或ox-LDL的75~82%,而ox-VLDL或ox-LDL的交叉竞争仅38~40%。表明ox-VLDL与ox-LDL有部分共同的构象与巨噬细胞的脂蛋白受体结合,但ox-VLDL不是经ox-LDL受体被巨噬细胞摄取。 相似文献
6.
有氧运动对高胆固醇血症大鼠肝脏低密度脂蛋白受体活性调节… 总被引:3,自引:0,他引:3
本文研究了实验性在醇血症大鼠肝脏低密度脂蛋白受体(LDL-R)活性变化及有氧运动时LDL-R活性调节的影响,发现,高脂(HC)组肝组织匀浆LDL-RI自古以来生较正常对照(NC)组降低37%(P〈0.05),同时血清大醇(TC)、低密度脂收白胆固醇(LDL-C)及血清栽脂蛋白B(ApoB)均显著高于NC组(P〈0.01);高脂+运动(HE)组TC、LDL-C及ApoB均明显低于HC组,而LDL-R 相似文献
7.
氧化修饰低密度脂蛋白与动脉粥样硬化 总被引:8,自引:0,他引:8
动脉粥样硬化的发生发展与低密度脂蛋白受到氧化修饰有关。本文从以下四个方面对本室的工作进行了综述:(1)动脉粥样硬化机体受到脂质过氧化损伤;(2)Ox-LDL对内皮细胞、平滑肌细胞和巨噬细胞的毒性效应;(3)Ox-LDL和MDA-LDL的比较及与Ox-LDL和MDA-LDL结合的清道夫受体的特征;(4)不同方法对LDL氧化修饰的比较和以LDL氧化修饰为模型对某些物质的抗氧化修饰研究。研究结果为动脉粥 相似文献
8.
我们以前的实验显示自发性高血压大鼠离体主动脉磷酸肌醇蓄积在无激动剂在的基础状态下就显著增高。根据G蛋白偶联受体固有活性假说,推测SHR主动脉中介导肌醇磷脂解的主要受体-α1D和α1B肾上腺素受体的第三细胞内环可能存在点突变。本实验通过PCR-SSCP鉴定,表明上述突变并不存在。 相似文献
9.
介导巨噬细胞摄取氧化修饰极低密试脂蛋白的受体 总被引:2,自引:1,他引:1
用未标记氧化修饰极低密度脂蛋白(ox-VLDL)、n-VLDL、乙酰LDL竞争^125I-ox-VLDL与巨噬细胞的结合。在浓度为200μg蛋白/ml时,分别抑制标记ox-VLDL结合量的70 ̄78%、60 ̄70%和25 ̄35%。用未标记ox-VLDL竞争^125I-n-VLDL与巨噬细胞的结合,能抑制77%。结果说明ox-VLDL主要通过n-VLDL受体进入巨噬细胞。以ox-VLDL与ox-LD 相似文献
10.
去甲肾上腺素引起的α1肾上腺素受体三种亚型脱敏过程的差异 总被引:2,自引:0,他引:2
将含有α1肾上腺素受体三种亚型的全长cDNA质粒分别转染到人胚肾脏细胞(HEK293),α1A-,α1B-和α1D-AR在HEK293细胞株上得到高水平稳定表达,用^3H-inositol标记和柱层析法测定细胞磷酸肌醇积。观察在去甲肾上腺素长期作用下α1三种受体亚型介导磷酸肌醇蓄积敏感性降低的差别。 相似文献
11.
Marsche G Zimmermann R Horiuchi S Tandon NN Sattler W Malle E 《The Journal of biological chemistry》2003,278(48):47562-47570
The presence of HOCl-modified epitopes inside and outside monocytes/macrophages and the presence of HOCl-modified apolipoprotein B in atherosclerotic lesions has initiated the present study to identify scavenger receptors that bind and internalize HOCl-low density lipoprotein (LDL). The uptake of HOCl-LDL by THP-1 macrophages was not saturable and led to cholesterol/cholesteryl ester accumulation. HOCl-LDL is not aggregated in culture medium, as measured by dynamic light scattering experiments, but internalization of HOCl-LDL could be inhibited in part by cytochalasin D, a microfilament disrupting agent. This indicates that HOCl-LDL is partially internalized by a pathway resembling phagocytosis-like internalization (in part by fluid-phase endocytosis) as measured with [14C]sucrose uptake. In contrast to uptake studies, binding of HOCl-LDL to THP-1 cells at 4 degrees C was specific and saturable, indicating that binding proteins and/or receptors are involved. Competition studies on THP-1 macrophages showed that HOCl-LDL does not compete for the uptake of acetylated LDL (a ligand to scavenger receptor class A) but strongly inhibits the uptake of copper-oxidized LDL (a ligand to CD36 and SR-BI). The binding specificity of HOCl-LDL to class B scavenger receptors could be demonstrated by Chinese hamster ovary cells overexpressing CD36 and SR-BI and specific blocking antibodies. The lipid moiety isolated from the HOCl-LDL particle did not compete for cell association of labeled HOCl-LDL to CD36 or SR-BI, suggesting that the protein moiety of HOCl-LDL is responsible for receptor recognition. Experiments with Chinese hamster ovary cells overexpressing scavenger receptor class A, type I, confirmed that LDL modified at physiologically relevant HOCl concentrations is not recognized by this receptor. 相似文献
12.
Wang X Greilberger J Ledinski G Kager G Jürgens G 《Journal of cellular biochemistry》2001,81(3):557-569
Oxidatively modified low-density lipoprotein (LDL) has been found in vivo, and oxidized LDL (oxLDL) could bind to scavenger receptors, leading to foam cell formation. Macrophages bear a number of different scavenger receptors for oxLDL, and macrophages of different origins may have a different scavenger receptor repertoire. In addition, LDL oxidized to different degrees may differ in the ability to bind macrophage scavenger receptors. In this study, we characterized the patterns of the binding and uptake of differently oxidized LDL in mouse peritoneal macrophages (MPM) and human THP-1 macrophages, and the influence of negative charge and oxidation-specific epitopes in oxLDL on these processes. Thresholds of increased binding and uptake in MPM were found when LDL was oxidized to the degrees with a relative electrophoretic mobility (REM) of 2.6 (minor threshold) and 3.0 (major threshold), corresponding to 49 and 57%, respectively, of the loss of free amino groups in these oxLDL. There was no threshold for the binding of oxLDL to THP-1 macrophages, while for uptake, a major threshold with REM of 3.0 (57% free amino groups lost) was found. The presence of the F(ab')(2) fragments of the monoclonal antibody OB/04, which was raised against copper-oxidized LDL, led to the reduction of the binding and uptake, respectively, of Eu(3+)-oxLDL (REM:3.6) in MPM by 31 and 29%, and by 19 and 22% in THP-1 macrophages. It is concluded that LDL oxidized to different degrees binds differently to macrophages, and the patterns of binding and uptake are different for MPM and human THP-1 macrophages. Both, the negative charge and the oxidation-specific epitopes of oxLDL are involved in these processes. 相似文献
13.
Differential effects of low-density lipoprotein and chylomicron remnants on lipid accumulation in human macrophages 总被引:2,自引:0,他引:2
Batt KV Avella M Moore EH Jackson B Suckling KE Botham KM 《Experimental biology and medicine (Maywood, N.J.)》2004,229(6):528-537
The effects of low-density lipoprotein (LDL) and chylomicron remnants on lipid accumulation in human monocyte-derived macrophages (HMDMs) and in macrophages derived from the human monocyte cell line THP-1 were compared. The HMDMs or THP-1 macrophages were incubated with LDL, oxidized LDL (oxLDL), chylomicron remnant-like particles (CMR-LPs), or oxidized CMR-LPs (oxCMR-LPs), and the amount and type of lipid accumulated were determined. As expected, the lipid content of both cell types was increased markedly by oxLDL but not LDL, and this was due to a rise in cholesterol, cholesteryl ester (CE), and triacylglycerol (TG) levels. In contrast, both CMR-LPs and oxCMR-LPs caused a considerable increase in cellular lipid in HMDMs and THP-1 macrophages, but in this case there was a greater rise in the TG than in the cholesterol or CE content. Lipid accumulation in response to oxLDL, CMR-LPs, and oxCMR-LPs was prevented by the ACAT inhibitor CI976 in HMDMs but not in THP-1 macrophages, where TG levels remained markedly elevated. The rate of incorporation of [(3)H]oleate into CE and TG in THP-1 macrophages was increased by oxLDL, CMR-LPs, and oxCMR-LPs, but incorporation into TG was increased to a greater extent with CMR-LPs and oxCMR-LPs compared with oxLDL. These results demonstrate that both CMR-LPs and oxCMR-LPs cause lipid accumulation in human macrophages comparable to that seen with oxLDL and that oxidation of the remnant particles does not enhance this effect. They also demonstrate that a greater proportion of the lipid accumulated in response to CMR-LPs compared with oxLDL is TG rather than cholesterol or CE and that this is associated with a higher rate of TG synthesis. This study, therefore, provides further evidence to suggest that chylomicron remnants have a role in foam cell formation that is distinct from that of oxLDL. 相似文献
14.
Yuki Imaizumi Yoichi Takami Koichi Yamamoto Motonori Nagasawa Yoichi Nozato Satoko Nozato Hikari Takeshita Cheng Wang Serina Yokoyama Hiroki Hayashi Kazuhiro Hongyo Hiroshi Akasaka Yasushi Takeya Ken Sugimoto Hironori Nakagami Hiromi Rakugi 《Biochemical and biophysical research communications》2019,508(4):1168-1174
Cardiovascular disease is one of the leading causes of death in the elderly, and novel therapeutic targets against atherogenesis are urgent. The initiation of atherosclerotic changes of monocyte adhesion on the vascular endothelium and subsequent foam cell formation are noteworthy pathophysiologies when searching for strategies to prevent the progression of age-related atherosclerosis. We report the significance of the deubiquitinating enzyme cylindromatosis (CYLD) in vascular remodeling by interference with inflammatory responses regulated by NF-κB signaling. The purpose of this study was to elucidate the pathological functions of CYLD in the early phase of atherogenesis associated with aging.Treatment with inflammatory cytokines induced endogenous CYLD in aortic endothelial cells (HAECs) and THP-1?cells. siRNA-mediated CYLD silencing led to enhanced monocyte adhesion along with increased adhesion molecules in HAECs treated with TNFα. In siRNA-mediated CYLD silenced RAW 264.7 macrophages treated with oxidized LDL (oxLDL), augmented lipid accumulation was observed, along with increased expression of the class A macrophage scavenger receptor (SR-A), lectin-like oxidized LDL receptor-1 (LOX-1), CD36, fatty acid binding protein 4 (FABP4), the cholesterol ester synthase acyl-CoA cholesterol acyltransferase (ACAT1), MCP-1, and IL-1β and decreased expression of scavenger receptor class B type I (SR-BI). Intriguingly, CYLD gene expression was significantly reduced in bone marrow-derived macrophages of aged mice compared that of young mice, as well as in senescent HAECs compared with young cells.These findings suggest that age-related attenuation of CYLD expression in endothelial cells (ECs) and macrophages triggers the initiation of age-related atherogenesis by exacerbating monocyte adhesion on the endothelium and foam cell formation. CYLD in the vasculature may be a novel therapeutic target, especially in the early preventive intervention against the initiation of age-related atherogenesis. 相似文献
15.
Dimitry A. Chistiakov Yuri V. Bobryshev Alexander N. Orekhov 《Journal of cellular and molecular medicine》2016,20(1):17-28
Formation of foam cells is a hallmark at the initial stages of atherosclerosis. Monocytes attracted by pro‐inflammatory stimuli attach to the inflamed vascular endothelium and penetrate to the arterial intima where they differentiate to macrophages. Intimal macrophages phagocytize oxidized low‐density lipoproteins (oxLDL). Several scavenger receptors (SR), including CD36, SR‐A1 and lectin‐like oxLDL receptor‐1 (LOX‐1), mediate oxLDL uptake. In late endosomes/lysosomes of macrophages, oxLDL are catabolysed. Lysosomal acid lipase (LAL) hydrolyses cholesterol esters that are enriched in LDL to free cholesterol and free fatty acids. In the endoplasmic reticulum (ER), acyl coenzyme A: cholesterol acyltransferase‐1 (ACAT1) in turn catalyses esterification of cholesterol to store cholesterol esters as lipid droplets in the ER of macrophages. Neutral cholesteryl ester hydrolases nCEH and NCEH1 are involved in a secondary hydrolysis of cholesterol esters to liberate free cholesterol that could be then out‐flowed from macrophages by cholesterol ATP‐binding cassette (ABC) transporters ABCA1 and ABCG1 and SR‐BI. In atherosclerosis, disruption of lipid homoeostasis in macrophages leads to cholesterol accumulation and formation of foam cells. 相似文献
16.
Atherogenesis and inflammation are dependent on macrophage function. Signalling pathways are involved in the modulation of the classical low density lipopotein (LDL)-receptor and scavenger receptors activities, which are both expressed by macrophages. This study has evaluated the role of activation of the protein kinase A and C pathways in human macrophages on the metabolism of lipid carried by native, acetylated and oxidised LDL. We found that [3H]oleate incorporation into cholesteryl ester and triacylglycerol is increased by an analogue of cAMP, but strongly inhibited by treatment with phorbol ester (PMA) (100 nM, 6 h) in the presence of acLDL and oxLDL and, to a lesser extent, nLDL. The mechanisms underlying the effects of the phorbol ester were investigated further. The protein kinase C inhibitors, calphostin C and herbimycin A, prevented the PMA-mediated inhibition of cholesterol esterification. PMA also reduced [14C]acetate incorporation into newly synthesised lipids especially in the presence of nLDL, and reduced the uptake of cholesterol carried by modified LDL. Furthermore, the effects of PMA were not modified by inhibition of proteases activities, ruling out the hypothesis that CD163, a scavenger receptor which is shed by the cell surface in the presence of phorbol, is involved in the phorbol-induced reduction of cholesterol accumulation in macrophages in response to LDL. We conclude that binding of modified LDL to macrophages induces an appropriate pattern of scavenger receptor phosphorylation which, in turn, determines the optimal receptor internalisation process. PMA activates PKC pathways and prevents the optimal ligand-induced phosphorylation of the receptors, compromising the processes of degradation of modified LDL. The data also suggest that this mechanism may be related to the decreased uptake by activated macrophages of lipid carried by modified lipoproteins during the early phases of inflammation (284). 相似文献
17.
THP-1 cells form foam cells in response to coculture with lipoproteins but not platelets 总被引:3,自引:0,他引:3
The human monocytic leukemia cell line, THP-1, shares many properties with human monocyte-derived macrophages and might be a useful model for studying foam cell formation in vitro. Therefore, we examined the ability of THP-1 cells to accumulate cholesteryl esters, the hallmark feature of foam cells, in response to culture with native low density lipoprotein (LDL), modified LDL, and platelets. THP-1 cells stored more cholesteryl esters than macrophages in response to 200 micrograms/ml of LDL. Down-regulation of LDL receptors occurred in macrophages at lower LDL concentrations than in THP-1 cells. Phorbol ester-treated THP-1 cells stored more cholesteryl esters than human macrophages in response to 25-200 micrograms/ml of acetylated LDL. Because we have previously demonstrated that activated platelets enhanced macrophage cholesteryl ester storage, we examined the ability of THP-1 cells to store cholesteryl esters in response to coculture with platelets. Compared with macrophages, dividing THP-1 cells and phorbol ester-treated THP-1 cells accumulated only 50% and 33% as much cholesteryl esters, respectively. Furthermore, although platelets induced a 90% reduction in cholesterol synthesis in macrophages by day 5, cholesterol synthesis in THP-1 cells and phorbol ester-treated THP-1 cells was inhibited less than 50% by platelets. Nevertheless, both THP-1 cells and macrophages responded to platelets by increasing their secretion of apolipoprotein E. Therefore, we conclude that dividing THP-1 cells and phorbol ester-treated THP-1 cells are capable of forming foam cells in response to physiologic doses of both LDL and acetylated LDL, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
18.
We examined the roles of phospholipase A2 (PLA2) in oxidized LDL (oxLDL)-induced cholesteryl ester formation in macrophages. In [3H]oleic acid-labeled RAW264.7 cells and mouse peritoneal macrophages, oxLDL induced [3H]cholesteryl oleate formation with an increase in free [3H]oleic acid and a decrease in [3H]phosphatidylcholine. The changes in these lipids were suppressed by methyl arachidonyl fluorophosphonate (MAFP), a cytosolic PLA2 (cPLA2) inhibitor. However, MAFP had no effect on the ACAT activity or the binding and/or uptake of oxLDL. Stimulation with oxLDL in the presence of [3H]cholesterol increased [3H]cholesteryl ester bearing fatty acyl chains derived from cellular and/or exogenous (oxLDL) lipids. The formation of cholesteryl ester under this condition was also inhibited by MAFP, and the inhibitory effect was reversed by adding oleic acid. While oxLDL did not affect the activity or amounts of cPLA2, preincubation with oxLDL enhanced the release of oleic acid and arachidonic acid induced by ionomycin in RAW264.7 cells. 13(S)-hydroxyoctadecadienoic acid, but not 7-ketocholesterol, also enhanced ionomycin-induced oleic acid release. These results suggest that oxLDL induces cPLA2 activation, which contributes, at least in part, to the supply of fatty acids required for the cholesteryl esterification, probably through the acceleration by oxidized lipids of the catalytic action of cPLA2 in macrophages. 相似文献
19.
20.
Lack of a direct role for macrosialin in oxidized LDL metabolism 总被引:2,自引:0,他引:2
de Beer MC Zhao Z Webb NR van der Westhuyzen DR de Villiers WJ 《Journal of lipid research》2003,44(4):674-685
Murine macrosialin (MS), a scavenger receptor family member, is a heavily glycosylated transmembrane protein expressed predominantly in macrophage late endosomes. MS is also found on the cell surface where it is suggested, on the basis of ligand blotting, to bind oxidized LDL (oxLDL). Here we report on the regulation of MS by an atherogenic high-fat diet and oxLDL, and on the inability of MS in transfected cells to bind oxLDL. MS expression was markedly increased in the livers of atherosclerosis-susceptible C57BL/6 and atherosclerosis-resistant C3H/HeJ mice fed an atherogenic high-fat diet. In resident-mouse peritoneal macrophages, treatment with oxLDL upregulated MS mRNA and protein expression 1.5- to 3-fold. MS, overexpressed in COS-7 cells through adenovirus mediated gene transfer, bound oxLDL by ligand blotting. However, no binding of oxLDL to MS was observed in intact transfected COS-7 and Chinese hamster ovary cells, despite significant cell surface expression of MS. Furthermore, inhibition of MS through gene silencing did not affect the binding of oxLDL to macrophages. We conclude that although MS expression in macrophages and Kupffer cells is responsive to a proatherogenic inflammatory diet and to oxLDL, MS does not function as an oxLDL receptor on the cell surface. 相似文献