单核—巨噬细胞和ECV304内皮细胞表达死亡相关蛋白

为研究单核——巨噬细胞和ECV304细胞是否表达死亡相关蛋白以及影响死亡相关蛋白表达的因素。分别用氧化型低密度脂蛋白(100mg／L)孵育THP-1细胞，H2O2(1mmol／L)孵育ECV304细胞，用逆转录聚合酶链反应检测死亡相关蛋白mRNA的表达。结果发现，THP-1细胞及ECV304细胞均表达死亡相关蛋白，氧化型低密度脂蛋白和H2O2能分别诱导THP-1细胞和ECV304细胞死亡相关蛋白mRNA表达增高。实验结果提示死亡相关蛋白可能参与调节氧化应激诱导的单核—巨噬细胞和内皮细胞的凋亡。     

Expression of class A scavenger receptor inhibits apoptosis of macrophages triggered by oxidized low density lipoprotein and oxysterol

The class A macrophage scavenger receptor (MSR-A) is a multifunctional trimeric glycoprotein involved in innate immune response as well as the development of lipid-laden foam cells during atherosclerosis. The MSR ligand, oxidized low density lipoprotein (oxLDL), is known to be cytotoxic to macrophages and other cell types. This study examined whether MSR mediates or modulates oxLDL-induced apoptosis. Treatment with oxLDL and its cytotoxic oxysterol, 7-ketocholesterol (7-KC), reduced viability and increased DNA fragmentation in human THP-1 cells, Chinese hamster ovary cells, and mouse peritoneal macrophages. However, cell death and DNA fragmentation were markedly diminished in the phorbol ester-differentiated MSR-expressing THP-1 cells and Chinese hamster ovary cells, with stable expression of MSR-AI after cDNA transfection when exposed to the same concentrations of oxLDL and 7-KC. Moreover, treatment with oxLDL and 7-KC induced much greater death and DNA fragmentation in MSR-A-deficient peritoneal macrophages compared with wild-type macrophages. Thus, MSR-A does not act as a receptor responsible for the apoptotic effect of oxLDL, and instead, expression of this receptor confers resistance of macrophages to the apoptotic stimulation by oxLDL and its cytotoxic lipid component. These results suggest that by preventing apoptosis, MSR-A may contribute to the long-term survival of macrophages and macrophage-derived lipid-laden foam cells in atherosclerotic lesions.     

Endothelial lipase enhances low density lipoprotein binding and cell association in THP-1 macrophages

OBJECTIVE: Endothelial lipase (EL) is expressed in macrophages in human atherosclerotic lesions. However, its specific metabolic role in human macrophages has not been fully explored. METHODS: The present study used lentivirus containing either shRNA or cDNA for EL to decrease or increase EL expression, respectively in THP-1 macrophages to investigate the consequence on LDL binding and cell association. RESULTS: EL suppression significantly decreased the binding and cell association of native LDL (52% and 33%) and mildly oxLDL (43% and 36%) as well as extensively oxLDL binding (36%) in THP-1 macrophages. EL overexpression markedly increased the binding and cell association of native LDL (3.1- and 2.2-fold), mildly oxLDL (1.9- and 1.4-fold), and extensively oxLDL (1.5- and 1.5-fold). An inactive mutant EL compromised EL-mediated cell association of native and mildly oxLDL but not extensively oxLDL. Heparinase treatment almost completely eliminated EL-mediated native and oxLDL binding and cell association in THP-1 macrophages. LDL receptor blocking by antibodies decreased EL-mediated native LDL binding and cell association by 24% and 54%, respectively. Neither receptor associated protein or CD36 antibody treatment led to changes in EL-mediated lipoprotein binding and cell association. Furthermore, wild-type and the catalytically inactive mutant EL increased lipid accumulation in THP-1 macrophages. CONCLUSIONS: EL expression promotes the binding and uptake of native and oxidized LDL in THP-1 macrophages in a heparan sulfate proteoglycan-dependent manner, and the LDL receptor was partly responsible for the EL-enhanced uptake of native LDL.     

Lipid metabolism mediated by adipocyte lipid binding protein (ALBP/aP2) gene expression in human THP-1 macrophages

The critical initiating event in atherogenesis involves the invasion of monocytes through the endothelial wall of arteries, and their transformation from macrophages into foam cells. Human THP-1 monocytic cells can be induced to differentiate into macrophages by phorbol myristate acetate (PMA) treatment, and can then be converted into foam cells by exposure to oxidized low-density lipoprotein (oxLDL). We previously reported that adipocyte lipid binding protein (ALBP/aP2) is a gene that is highly up-regulated in foam cells in response to oxLDL. Here, we showed that overexpression of the ALBP gene using a lentiviral construct in macrophage foam cells enhanced the accumulations of cholesterol and triglyceride, probably due to an increased expression of the scavenger receptor type AI (SR-AI), which plays an important role in cell lipid metabolism. Moreover, we determined that the expression of acyl-coenzyme A: cholesterol-acyltransferase 1 (ACAT1) gene was up-regulated by the overexpression of ALBP gene, and on the other hand, the ATP-binding cassette A1 (ABCA1) gene and hormone sensitive lipase (HSL) gene, which mediate separately cholesterol efflux and cholesterol ester hydrolysis in the macrophage cells, were down-regulated by the overexpression of ALBP gene in these cells. Finally, our data indicated that oxLDL regulates expression of ALBP related to two peroxisome proliferator-responsive elements (PPREs) which are located in ALBP promoter region. These results have determined that ALBP gene expression accelerates cholesterol and triglyceride accumulation in macrophage foam cells and affects some key gene expression for lipid metabolism, suggesting some pivotal roles of ALBP in lipid metabolism for macrophage foam cell formation.     

8-isoprostane increases expression of interleukin-8 in human macrophages through activation of mitogen-activated protein kinases

BACKGROUND AND OBJECTIVES: 8-isoprostane is a marker of oxidative stress in vivo and increased plasma and urine levels are found in patients with vascular disease and in atherosclerotic plaques. Inflammatory chemokines such as interleukin (IL)-8 seem to play an important pathogenic role in atherogenesis. We therefore investigated the effects of 8-isoprostane on the expression of inflammatory chemokines with consciousness on IL-8 (mRNA and protein) in human macrophages. In addition, we studied the involvement of mitogen-activated protein kinases (ERK 1/2 and p38 MAPK) and nuclear factor-kappaB (NF-kappaB) in this process. METHODS AND RESULTS: 8-isoprostane (10 microM) induced IL-8 expression (mRNA and protein), measured by real-time quantitative RT-PCR and enzyme immunoassay, respectively, in both THP-1 macrophages and human monocyte-derived macrophages. Moreover, 8-isoprostane increased mRNA expression of macrophage inflammatory protein-1alpha as determined by RNase protection assay. In this process, 8-isoprostane induced the activation of two major MAP-kinases; ERK 1/2 and p38 MAPK. Furthermore, the ERK 1/2 inhibitor, PD98059, and the p38 MAPK inhibitor, SB203580, markedly reduced 8-isoprostane-induced IL-8 expression (mRNA and protein), while inhibition of NF-kappaB activation and translocation had no significant effect on IL-8 expression. CONCLUSIONS: We show that 8-isoprostane increases IL-8 expression in human macrophages involving both ERK 1/2 and p38 MAPK, but not NF-kappaB signaling pathway. These findings further support a link between oxidative stress/lipid peroxidation and inflammation in human macrophages and suggest a role for 8-isoprostane in this process. This 8-isoprostane-induced chemokine expression might be involved in the pathogenesis of atherosclerosis as well as other inflammatory disorders.     

三苯氧胺抑制促动脉粥样硬化基因CD36在单核-巨噬细胞的表达

目的 观察抗肿瘤药物三苯氧胺(tamoxifen,Tam)对促动脉粥样硬化基因CD36在单核-巨噬细胞表达的影响。方法 分别以不同浓度Tam(1,5,10 μmol/L)和它的活性代谢物羟-三苯氧胺(OH-Tam)作用于培养的THP-1单核细胞,24 h后观察CD36蛋白在细胞表面的表达;以氧化型低密度脂蛋白(100mg/L)刺激THP-1单核-巨噬细胞CD36表达,并给予Tam或OH-Tam处理,流式细胞术观察CD36的变化。结果 Tam和OH-Tam可降低单核细胞CD36蛋白表达;同时对氧化型低密度脂蛋白引起的单核-巨噬细胞CD36表达上调具有抑制作用。结论 Tam可能通过抑制CD36在单核-巨噬细胞的表面表达来发挥其抗动脉粥样硬化作用。     

氧化型低密度脂蛋白致PC12细胞的毒性作用及抗氧化剂的细胞保护作用

目的探讨氧化型低密度脂蛋白(oxLDL)致PC12细胞的毒性作用及白藜芦醇等抗氧化剂的细胞保护作用。方法 通过噻唑蓝(MTT)实验、乳酸脱氢酶(LDH)释放实验、DNA断端原位末端标记法(TUNEL)实验及caspase-3测定来观察oxLDL对PC12细胞存活率、细胞膜通透性、细胞核及caspase-3活性的影响。抗氧化剂白藜芦醇、丙丁酚及维生素E预处理细胞,再加入不同浓度oxLDL,观察抗氧化剂的细胞保护作用。结果 PC12细胞存活率随着ox-LDL浓度及作用时间增加而下降;LDH释放率、TUNEL阳性细胞数及caspase-3活性随着浓度增高而增高;低密度脂蛋白(LDL)对上述各项指标无影响。白藜芦醇、丙丁酚及维生素E均能减缓oxLDL所致的细胞存活率下降、LDH释放率的升高、TUNEL阳性细胞数的增加,其中白藜芦醇作用最强;白藜芦醇、丙丁酚减缓oxLDL所致的caspase-3活性增高,而维生素E对caspase-3活性无影响。结论oxLDL导致PC12细胞死亡,其浓度与PC12细胞存活率呈剂效关系,其作用时间与PC12细胞成活率呈时效关系。     

Chylomicron remnants stimulate release of interleukin-1beta by THP-1 cells

Recent findings suggest that the oxidative modification of low-density lipoproteins (LDL) and an increase in triglyceride-rich lipoprotein particles including chylomicron remnants contribute to the progression of atherosclerosis, as does the inflammatory response. We therefore examined whether and how these lipoproteins affected interleukin (IL)-1beta release and mRNA expression for IL-1beta and IL-18 in THP-1 cells, a human monocyte cell line. Chylomicron remnants increased IL-1beta release into the conditioned medium by THP-1 in a dose- and time-dependent manner. At concentrations up to 1 microg/ml, chylomicron remnants increased IL-1beta release by 4-fold compared with the control. Neither native LDL nor oxidized LDL (OxLDL) significantly increased IL-1beta release. Chylomicron remnants increased IL-1beta mRNA expression by 3 times. Native LDL or OxLDL did not increase IL-1beta mRNA, while neither these lipoproteins nor chylomicron remnants increased IL-18 mRNA. Chylomicron remnants also increased the activities of caspase-1 and nuclear factor (NF)-kappaB significantly, while native LDL or OxLDL did not. In conclusion, chylomicron remnants stimulated IL-1beta mRNA expression and IL-1beta protein production probably via caspase-1 and NF-kappaB activation in THP-1 cells.     

人巨噬细胞源泡沫细胞分化过程中MaxiK通道的发育转变

目的:研究人巨噬细胞发育及其向泡沫细胞分化过程中MaxiK通道的表达和电生理学特征。方法: 以健康人外周血单核细胞源性巨噬细胞为研究对象,采用Real time RT-PCR和Western blot技术观察MaxiK通道α亚单位mRNA及蛋白的表达;膜片钳技术分析MaxiK通道的电生理学特征。结果: 在巨噬细胞发育过程中,MaxiK通道α亚单位的表达被轻度上调。同培养5 d的细胞相比,7.5 d细胞的mRNA及蛋白表达增加分别约为1.06和1.44倍,但无统计学意义。然而,30 mg/L oxLDL显著提高MaxiK通道α亚单位的表达,在其分化成泡沫细胞后,mRNA和蛋白表达分别是培养5 d细胞的2.4和7.27倍,有显著的差异（P<0.05）。在所有培养5 d、7.5 d和oxLDL组中的巨噬细胞上均能记录到典型的MaxiK电流;MaxiK通道的选择性阻断剂- paxilline（10 μmol/L）抑制时间依从性电流、几乎全部的外向电导和噪声;但是,在培养5 d、7.5 d和oxLDL组中的巨噬细胞上MaxiK电流密度分别是(36±6) pA/pF、(35.9±3.5) pA/pF和(32.4±6.9) pA/pF,无明显差异。结论: 在人巨噬细胞发育过程中,MaxiK通道的表达被上调,分化成泡沫细胞后尤为显著,但其介导的电流没有改变。     

弓形虫感染对THP-1巨噬细胞极化影响的研究

目的 探讨弓形虫感染对体外诱导的人外周血单核细胞(Human acute monocytic leukemia cell line,THP-1)极化特点的影响。方法 用佛波酯(PMA)诱导THP-148 h使之由悬浮的单核细胞诱导为贴壁的巨噬细胞,体外选择不同时间点感染弓形虫,用Diff染色分析弓形虫在细胞内的增殖情况。Western blot检测极化相关蛋白,Q-PCR检测mRNA的表达情况。结果 成功诱导得到贴壁的巨噬细胞模型,感染弓形虫后,M1型巨噬细胞标志性蛋白iNOS 及M2型巨噬细胞标志型蛋白Arg-1 36 h表达量与对照组差异明显(t=10.23,P<0.05)。Q-PCR的结果显示不同的处理组IL-1、IL-12、iNOS和TNF-α逐渐减少,而IL-10、Arg-1呈逐渐增加,到36 h达到顶峰(t=9.587,P<0.05)。结论 弓形虫RH株感染THP-1巨噬细胞后可以在胞内生长增殖,THP-1细胞感染后向M2型巨噬细胞方向极化。     

普罗布考抑制氧化低密度脂蛋白上调巨噬细胞清道夫受体CD36的表达

背景普罗布考是一降脂药，同时具有抗氧化特性，近年来的研究表明其可以通过多种机制抑制动脉粥样硬化的形成，降低经皮冠状动脉成形术后再狭窄的发生。目的探讨普罗布考对氧化低密度脂蛋白（Ox-LDL）刺激巨噬细胞后清道夫受体CD36表达的抑制效应。方法用不同浓度的Ox-LDL刺激人单核细胞系THP-1源性巨噬细胞及用不同浓度普罗布考和核因子κBp65（NF-κBp65）特异性抑制剂（PDTC）预处理细胞后再用氧化低密度脂蛋白刺激，半定量RT—PCR方法检测CD36和NF-κBp65的mRNA的表达，Western-blot检测CD36和细胞核NF-κBp65蛋白表达水平。结果THP-1单核细胞分化成巨噬细胞后，CD36和NF-κBp65 mRNA和蛋白的表达上调；不同浓度的Ox-LDL刺激后，CD36mRNA和蛋白的表达呈浓度依赖性增加，同时伴NF-κBp65 mRNA和蛋白的表达增加；PDTC和普罗布考干预后，NF-κBp65和CD36的mRNA和蛋白表达下调。结论Ox-LDL可以通过NF-κBp65途径上调巨噬细胞CD36的表达；而普罗布考则可以抑制CD36的表达，这种作用与抑制NF-κBp65有关。     

Limitin, an interferon-like cytokine, transduces inhibitory signals on B-cell growth through activation of Tyk2, but not Stat1, followed by induction and nuclear translocation of Daxx

OBJECTIVE: Limitin, an interferon-like cytokine, suppresses B lymphopoiesis through ligation of the interferon-alpha/beta (IFN-alpha/beta) receptor. The aim of this study was to examine the intracellular signal transduction pathways activated by limitin. MATERIALS AND METHODS: The effects of limitin on cell growth, the activation of Jak kinase and Stat proteins, and the induction of interferon regulatory factor-1 (IRF-1) and Daxx were examined using the mouse pre-B-cell line 18.81, wild-type, and Tyk2-deficient mouse bone marrow cells. In addition, the change of localization of the Daxx protein after limitin treatment in wild-type and Tyk2-deficient mice was examined. RESULTS: Limitin phosphorylates Tyk2, Jak1, Stat1, and Stat2 and rapidly induces IRF-1 mRNA production. Phosphorylation of Stat1 by limitin is partially dependent on Tyk2. Suppression of B-cell growth by limitin, however, is severely impaired in the absence of Tyk2, whereas it is unaffected by the absence of Stat1. Limitin also induces the expression and nuclear translocation of Daxx, which is essential for IFN-alpha-induced inhibition of B-lymphocyte development. The absence of Tyk2 abrogates this induction of Daxx expression and nuclear translocation. CONCLUSIONS: Limitin suppresses B-cell growth through activation of Tyk2, resulting in the up-regulation and nuclear translocation of Daxx. This limitin-mediated signaling pathway does not require Stat1.     

NOD1/RIP2信号通路对巨噬细胞炎性活化的作用

目的以人单核细胞株THP-1为基础,探讨NOD1/受体相互作用蛋白2(RIP2)信号通路对巨噬细胞炎性活化及表型的影响。方法用160 nmo L/L的佛波酯(PMA)将THP-1单核细胞诱导分化成巨噬细胞,分别用10、25和50 mg/L浓度的氧化型低密度脂蛋白(ox-LDL)刺激THP-1源性巨噬细胞24 h,以空白组为对照组。应用RT-PCR法检测NOD1和RIP2的mRNA表达情况;应用Western blot法检测NOD1和RIP2的蛋白表达情况;应用ELISA法检测细胞培养液中单核细胞趋化蛋白1(MCP-1)和巨噬细胞移动抑制因子(MIF)的分泌;应用流式细胞学检测巨噬细胞表面抗原CD16、CD68表达。结果 ox-LDL能以剂量依赖的方式激活THP-1源性巨噬细胞中NOD1/RIP2信号通路,随着ox-LDL刺激浓度的增加,NOD1、RIP2的mRNA和蛋白表达水平升高(P0.05)。NOD1/RIP2信号通路激活后能使细胞培养物上清液中炎症因子MIF和MCP-1的表达增加,随着ox-LDL刺激浓度的增加,MCP-1和MIF的分泌增多(P0.05)。NOD1/RIP2信号通路激活后能改变巨噬细胞表面抗原CD16、CD68的表达,随着ox-LDL刺激浓度的变化,巨噬细胞表面抗原CD16/CD68的平均荧光强度发生变化,其中50 mg/L组能显著下调CD16/CD68的表达(P0.01)。结论巨噬细胞中NOD1/RIP2信号通路能被ox-LDL以剂量依赖的方式激活,NOD1/RIP2信号通路激活后能导致巨噬细胞的炎性活化及其表型变化,这可能是其参与动脉粥样硬化形成和发展过程的主要机制。     

Unsaturated fatty acids and their oxidation products stimulate CD36 gene expression in human macrophages

Fatty acids (FA) have been implicated in the control of expression of several atherosclerosis-related genes. Similarly, the CD36 receptor has recently been shown to play an important role in atherosclerosis and other pathologies. The aim of the present study was to evaluate the direct effect of FA and their oxidation products (aldehydes), on the expression of CD36 in both THP-1 macrophages and human monocyte-derived macrophages (HMDM). The FA tested included the saturated FA (SFA) lauric, myristic, palmitic and stearic acid; the monounsaturated FA oleic acid; and the unsaturated FA (UFA) linoleic, arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Aldehydes used were malondialdehyde (MDA), hexanal, 2,4-decadienal (DDE) and 4-hydroxynonenal (HNE). CD36 expression was measured by RT-PCR, Western blot and immunofluorescence. Incubation of THP-1 macrophages for 24 h with non-cytotoxic concentrations of UFA significantly increased CD36 mRNA expression. By contrast, exposure of THP-1 macrophages to SFA did not affect the levels of CD36 mRNA. Among all UFAs tested, EPA and DHA were the strongest inducers of CD36 mRNA levels, followed by oleic and linoleic acid. Incubation of HMDM with either oleic or linoleic acid significantly increased steady-state CD36 mRNA in a dose-dependent manner. Consistent with the increase of CD36 mRNA expression, incubation of THP-1 macrophages with oleic and linoleic acid for 24 h markedly increased CD36 protein expression. Treatment of THP-1 macrophages with MDA or hexanal for 24 h significantly increased CD36 mRNA expression in a dose dependent manner. In contrast, DDE and HNE significantly decreased this parameter. The data provide evidence for a direct regulatory effect of UFA on CD36 gene expression and support a role for aldehydes in the regulation of CD36 expression by FA.     

小檗碱对2型糖尿病大鼠肺泡和腹腔巨噬细胞氧化低密度脂蛋白及脂蛋白脂酶的影响

目的探讨小檗碱对2型糖尿病大鼠血脂及肺泡和腹腔巨噬细胞氧化低密度脂蛋白(oxidized low-density lipoprotein,ox-LDL)、脂蛋白脂酶(lipoprotein lipase,LPL)表达的影响。方法SD大鼠分4组,正常对照组、高脂组、糖尿病组、小檗碱治疗组,治疗结束后测定各组大鼠血清葡萄糖、胰岛素和血脂含量,并检测肺泡巨噬细胞和腹腔巨噬细胞ox-LDL含量和LPL mRNA的表达水平。结果(1)小檗碱对糖尿病大鼠具有降低血糖、胰岛素水平和调节脂代谢紊乱等作用;(2)经小檗碱治疗后糖尿病大鼠肺泡和腹腔巨噬细胞ox-LDL含量下降,LPL mRNA表达降低。结论推测小檗碱对糖尿病大鼠的治疗作用可能与提高胰岛素敏感性,降低巨噬细胞ox-LDL、LPL表达有关。     

Granulocyte colony-stimulating factor inhibits the mitochondria-dependent activation of caspase-3 in neutrophils.

The exact mechanism of apoptosis in neutrophils (PMNs) and the explanation for the antiapoptotic effect of granulocyte colony-stimulating factor (G-CSF) in PMNs are unclear. Using specific fluorescent mitochondrial staining, immunofluorescent confocal microscopy, Western blotting, and flow cytometry, this study found that PMNs possess an unexpectedly large number of mitochondria, which are involved in apoptosis. Spontaneous PMN apoptosis was associated with translocation of the Bcl-2-like protein Bax to the mitochondria and subsequent caspase-3 activation, but not with changes in the expression of Bax. G-CSF delayed PMN apoptosis and prevented both associated events. These G-CSF effects were inhibited by cycloheximide. The general caspase inhibitor z-Val-Ala-DL-Asp-fluoromethylketone (zVAD-fmk) prevented caspase-3 activation and apoptosis in PMNs, but not Bax redistribution. PMN-derived cytoplasts, which lack a nucleus, granules, and mitochondria, spontaneously underwent caspase-3 activation and apoptosis (phosphatidylserine exposure), without Bax redistribution. zVAD-fmk inhibited both caspase-3 activation and phosphatidylserine exposure in cultured cytoplasts. Yet, G-CSF prevented neither caspase-3 activation nor apoptosis in cytoplasts, confirming the need for protein synthesis in the G-CSF effects. These data demonstrate that (at least) 2 routes regulate PMN apoptosis: one via Bax-to-mitochondria translocation and a second mitochondria-independent pathway, both linked to caspase-3 activation. Moreover, G-CSF exerts its antiapoptotic effect in the first, that is, mitochondria-dependent, route and has no impact on the second.     

弓形虫ROP16蛋白在人白血病细胞THP-1表达及对其细胞增殖与凋亡的影响北大核心CSCD

目的探讨弓形虫Ⅱ型(Me49)ROP16蛋白在急性单核细胞白血病细胞株THP-1中的表达及其对THP-1细胞增殖与凋亡的影响。方法构建过表达ROP16(overExp-ROP16)和空载体(overExp-NC)慢病毒,通过转染THP-1细胞,72 h后观察荧光表达情况,采用PCR与Western blot验证ROP16在THP-1细胞中的表达。免疫荧光技术检测ROP16蛋白在THP-1细胞中的定位。CCK-8与流式细胞术检测细胞增殖及凋亡。采用qRT-PCR检测细胞凋亡相关因子Bcl-2、Bax、Caspase-3 mRNA相对表达水平。Western blot检测Bax、Bcl-2、Pro-Caspase-3和Cleaved-Caspase-3蛋白的表达变化。结果构建的过表达ROP16重组慢病毒转染到THP-1细胞后,可观察强荧光信号,ROP16蛋白在THP-1细胞中成功表达。免疫荧光结果表明ROP16蛋白定位于THP-1细胞核。CCK-8与流式细胞术证实ROP16蛋白抑制THP-1细胞的增殖并促进其凋亡(均P<0.05)。与对照组相比,过表达组促凋亡因子Bax、Caspase-3 mRNA高表达(P<0.05),抗凋亡因子Bcl-2 mRNA低表达(P<0.01),Bax与Cleaved-Caspase-3蛋白水平上调(P<0.01),Bcl-2与Pro-Caspase-3蛋白水平下调(P<0.01)。结论构建的慢病毒表达质粒overExp-ROP16可在急性单核细胞白血病细胞株THP-1中表达且通过入核调节凋亡蛋白Bcl-2、Bax、Caspase-3而抑制THP-1细胞增殖,促进其凋亡。     

Urokinase plasminogen activator (uPA) stimulates cholesterol biosynthesis in macrophages through activation of SREBP-1 in a PI3-kinase and MEK-dependent manner

Urokinase plasminogen activator (uPA) is expressed in human atherosclerotic lesions, predominantly in macrophages, and contributes to atherosclerosis progression. Since atherogenesis is characterized by the formation of cholesterol-loaded macrophage foam cells, we questioned whether uPA atherogenicity may involve macrophage cholesterol accumulation, and by what mechanisms. uPA increased cellular cholesterol content by 44% (mainly unesterified cholesterol) in THP-1 macrophages, and this effect was inhibited by statins. This effect was associated with 172% elevated cholesterol biosynthesis, which required the binding of uPA to its receptor. An upregulation of HMGCoA reductase (HMGCR) expression (protein and mRNA) was noted. Since HMGCR expression is controlled by sterol regulatory element-binding proteins (SREBPs), we next analyzed this issue. Indeed, treatment of macrophages with uPA increased SREBP-1 processing, and mature SEREBP-1 content (by 5.7-fold) in the nucleus. These latter effects were mediated by uPA-induced activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK). Finally, uPA was found to activate MAP-kinase through PI3 kinase (PI3K), as PI3K inhibition abrogated both uPA-induced ERK phosphorylation and cholesterol biosynthesis. In conclusion, uPA-induced macrophage cholesterol accumulation is a novel pathway by which uPA may contribute to accelerated atherosclerosis development. These findings provide new insight into the atherogenicity of uPA and may suggest new novel therapeutic means.