脂肪分化相关蛋白促进RAW 264.7细胞内酰基辅酶A:胆固醇酰基转移酶1高表达

目的 观察高表达脂肪分化相关蛋白细胞内酰基辅酶A∶胆固醇酰基转移酶1表达的变化,阐明脂肪分化相关蛋白促进细胞内脂质蓄积的机制.方法 构建的pQCXIP-HA-Adi逆转录病毒载体转染PA317包装细胞,获得pQCXIP-HA-Adi逆转录病毒.用病毒感染RAW 264.7细胞, Puromycin筛选后获得稳定高表达脂肪分化相关蛋白的RAW264.7细胞株.应用逆转录聚合酶链反应和免疫印迹法检测经感染后细胞内脂肪分化相关蛋白和酰基辅酶A∶胆固醇酰基转移酶1的表达.并应用阿托伐他汀处理高表达脂肪分化相关蛋白的RAW 264.7细胞,观察酰基辅酶A∶胆固醇酰基转移酶1表达的改变.结果 用pQCXIP-HA-Adi逆转录病毒感染RAW 264.7细胞后,脂肪分化相关蛋白和酰基辅酶A∶胆固醇酰基转移酶1 mRNA和蛋白表达明显升高,而对照组表达无明显变化.加入阿托伐他汀后,即在去除底物对酰基辅酶A∶胆固醇酰基转移酶1表达影响的情况下,高表达脂肪分化相关蛋白细胞内酰基辅酶A∶胆固醇酰基转移酶1表达仍升高.结论 高表达脂肪分化相关蛋白可明显上调RAW 264.7细胞酰基辅酶A∶胆固醇酰基转移酶1的表达.     

脂肪分化相关蛋白通过酰基辅酶A∶胆固醇酰基转移酶1促进巨噬细胞脂质蓄积

目的观察高表达脂肪分化相关蛋白对酰基辅酶A∶胆固醇酰基转移酶1表达及脂质蓄积的影响。方法构建表达载体pcDNA3.1-HA-脂肪分化相关蛋白,使用THP-1巨噬细胞,通过瞬时转染使之高表达脂肪分化相关蛋白,依次用氧化型低密度脂蛋白和(或)丙泮尼地处理。逆转录聚合酶链反应和Western blot检测酰基辅酶A∶胆固醇酰基转移酶1及脂肪分化相关蛋白的表达,油红O染色和高效液相色谱检测细胞内脂质的蓄积。结果随着氧化型低密度脂蛋白浓度的增加,巨噬细胞脂肪分化相关蛋白及酰基辅酶A∶胆固醇酰基转移酶1表达明显增强,两者呈伴行关系。丙泮尼地能抑制酰基辅酶A∶胆固醇酰基转移酶1表达上调,且随处理时间延长,其表达逐渐减少,并且能减少细胞内脂滴生成。与对照组相比,瞬时转染pcDNA3.1-HA-脂肪分化相关蛋白能使脂肪分化相关蛋白表达明显升高。高表达脂肪分化相关蛋白的巨噬细胞能使酰基辅酶A∶胆固醇酰基转移酶1表达增加,促进细胞内胆固醇酯蓄积,并协同增强氧化型低密度脂蛋白的作用。加入丙泮尼地后,高表达脂肪分化相关蛋白的作用被减弱。结论高表达脂肪分化相关蛋白能上调THP-1巨噬细胞酰基辅酶A∶胆固醇酰基转移酶1表达,促进细胞内脂质蓄积。脂肪分化相关蛋白可能通过酰基辅酶A∶胆固醇酰基转移酶1促进细胞内胆固醇酯的蓄积。     

酰基辅酶A胆固醇酰基转移酶1基因过表达对泡沫细胞形成的影响

目的研究在三种不同细胞中过表达酰基辅酶A胆固醇酰基转移酶1基因对泡沫细胞形成的影响。方法构建携带酰基辅酶A胆固醇酰基转移酶1全长cDNA的pCDNA3.1质粒载体并稳定转染体外培养的人THP-1单核细胞、小鼠RAW264.7单核巨噬细胞和人胚肾293上皮细胞,以油红O染色法检测在乙酰化低密度脂蛋白作用下转染前后三种细胞形成泡沫细胞的情况。结果在相同的脂质负荷条件下,转染酰基辅酶A胆固醇酰基转移酶1基因的THP-1单核细胞和RAW264.7巨噬细胞同未转染的细胞相比泡沫细胞的形成数量增加,而人胚肾293上皮细胞无论是否转染酰基辅酶A胆固醇酰基转移酶1基因均不易形成泡沫细胞。结论单核巨噬细胞中过表达酰基辅酶A胆固醇酰基转移酶1基因可促进泡沫细胞的形成。     

酰基辅酶A胆固醇酰基转移酶-1与动脉粥样硬化

酰基辅酶A胆固醇酰基转移酶目前认为是细胞内唯一合成胆固醇酯的酶,维持着细胞以及生物体胆固醇代谢的平衡,而酰基辅酶A胆固醇酰基转移酶-1在动脉粥样硬化的发生、发展过程中发挥着至关重要的作用。自从酰基辅酶A胆固醇酰基转移酶的cDNA在1993年首次被克隆之后,许多学者对酰基辅酶A胆固醇酰基转移酶-1进行了大量的研究,现就近年来酰基辅酶A胆固醇酰基转移酶-1与动脉粥样硬化关系的研究予以综述。     

内脂素通过过氧化体增殖物激活型受体γ信号转导通路上调酰基辅酶A∶胆固醇酰基转移酶1的表达

目的观察过氧化体增殖物激活型受体γ信号转导通路在内脂素调控人THP-1单核细胞源性巨噬细胞酰基辅酶A∶胆固醇酰基转移酶1表达中的作用,探讨内脂素诱导泡沫细胞形成的机制和途径。方法 THP-1单核细胞诱导分化为巨噬细胞,随机分组,给予不同浓度的内脂素和过氧化体增殖物激活型受体γ激动剂罗格列酮进行干预,分别运用油红O染色法观察细胞内脂滴形成情况,逆转录聚合酶链反应法和免疫印迹法检测细胞过氧化体增殖物激活型受体γ和酰基辅酶A∶胆固醇酰基转移酶1mRNA和蛋白的表达,酶荧光学法检测细胞内总胆固醇和游离胆固醇含量,总胆固醇与游离胆固醇之差为胆固醇酯含量。结果与对照组比较,内脂素组细胞内脂滴形成增加,过氧化体增殖物激活型受体γmRNA和蛋白表达水平降低(P0.05),酰基辅酶A∶胆固醇酰基转移酶1mRNA和蛋白表达水平升高(P0.05),细胞内胆固醇酯含量升高(P0.05);随着内脂素浓度(10-7mol/L、10-6mol/L和10-5mol/L)升高,过氧化体增殖物激活型受体γmRNA和蛋白表达水平逐渐降低(r值分别为-0.73和-0.83,P0.05),酰基辅酶A∶胆固醇酰基转移酶1mRNA和蛋白表达水平逐渐升高(r值分别为0.91和0.72,P0.05)。与内脂素组比较,罗格列酮组酰基辅酶A∶胆固醇酰基转移酶1mRNA和蛋白表达水平降低(P0.05),细胞内胆固醇酯含量降低(P0.05);随着罗格列酮浓度(10μmol/L、15μmol/L和20μmol/L)升高,酰基辅酶A∶胆固醇酰基转移酶1mRNA和蛋白表达水平逐渐降低(r值分别为-0.69和-0.84,P0.05)。结论内脂素呈浓度依赖性下调THP-1单核细胞源性巨噬细胞过氧化体增殖物激活型受体γ的表达,上调酰基辅酶A∶胆固醇酰基转移酶1的表达,而罗格列酮呈浓度依赖性抑制内脂素所诱导的上述效应。提示内脂素可能通过过氧化体增殖物激活型受体γ信号转导通路上调酰基辅酶A∶胆固醇酰基转移酶1表达,使细胞内胆固醇酯合成增加,从而诱导泡沫细胞形成。     

胆固醇诱导未折叠蛋白反应及其调节酰基辅酶A胆固醇酰基转移酶2基因的表达

目的探讨胆固醇对肝细胞和小肠粘膜上皮细胞中未折叠蛋白反应及其调节酰基辅酶A胆固醇酰基转移酶2基因表达的影响。方法以不同浓度(10mg/L和20mg/L)的游离胆固醇和氧化胆固醇温育肝癌细胞系HepG2细胞和小肠粘膜上皮细胞系Caco2细胞,应用半定量逆转录聚合酶链反应法检测两种细胞中X盒结合蛋白1和酰基辅酶A胆固醇酰基转移酶2mRNA的表达水平。结果随着游离胆固醇和氧化胆固醇温育浓度的升高,HepG2细胞和Caco2细胞中的X盒结合蛋白1和酰基辅酶A胆固醇酰基转移酶2mRNA表达均上调,呈现浓度依赖性。结论胆固醇和氧化胆固醇均可诱导未折叠蛋白反应中标记分子X盒结合蛋白1的表达,并上调酰基辅酶A胆固醇酰基转移酶2的表达,提示酰基辅酶A胆固醇酰基转移酶2的表达可能受未折叠蛋白反应的调控;鉴于酰基辅酶A胆固醇酰基转移酶2在胆固醇吸收的酯化过程中具有重要作用,未折叠蛋白反应可能在胆固醇吸收调控中具有重要意义。     

脂肪分化相关蛋白通过抑制中性胆固醇酯水解酶表达促进RAW264.7细胞内脂质积蓄

目的探讨RAW264.7巨噬细胞中脂肪分化相关蛋白(adipophilin)调控中性胆固醇酯水解酶(nCEH)表达进而介导脂质积蓄的作用机制。方法用已成功构建的沉默与高表达Adipophilin的逆转录病毒质粒载体转染包装细胞PA317,继而收集病毒液感染RAW264.7巨噬细胞,筛选出Adipophilin沉默细胞株和高表达细胞株。逆转录聚合酶链反应(RT-PCR)和蛋白免疫印迹分析技术(Western blot)分别检测nCEH的mRNA和蛋白表达水平,液体闪烁计数仪、高效液相色谱法检测细胞内胆固醇流出及胆固醇酯含量。结果 (1)高表达Adipophilin的细胞组胆固醇、胆固醇酯含量明显高于空白对照组(P0.01),而沉默Adipophilin表达的细胞组则显著低于空白对照组(P0.01),Adipophilin可抑制nCEH mRNA和蛋白的表达。(2)用100 nmol/L蛋白激酶Cδ(PKCδ)激动剂佛波酯(PMA)孵育高表达Adipophilin的RAW264.7细胞30 min后,nCEH的mRNA与蛋白表达水平明显降低(P0.05),而用100 nmol/L PKCδ抑制剂卡马拉素(Rottlerin)同样孵育30 min后,nCEH的表达水平较对照组增高(P0.05)。结论 Adipophilin促进巨噬细胞内脂质积蓄可能通过抑制nCEH表达来实现,在这一调控机制中PKCδ发挥了重要作用。     

亲环素A在巨噬细胞荷脂过程中的影响

目的观察胆固醇转运复合物中关键蛋白亲环素A在氧化型低密度脂蛋白诱导的巨噬细胞荷脂过程中的表达变化及其与细胞内胆固醇蓄积的关系,进而分析亲环素A在巨噬源性泡沫细胞形成过程中的作用。方法采用75 mg/L氧化型低密度脂蛋白与RAW264.7细胞共同孵育,建立巨噬细胞荷脂化模型;Western-blot、免疫荧光法检测亲环素A蛋白的表达水平;高效液相色谱法检测细胞内胆固醇含量的变化。结果75 mg/L氧化型低密度脂蛋白与RAW264.7细胞共同孵育48 h后,亲环素A的蛋白表达逐渐减弱,48 h、72 h分别较未处理组下降了54.5%±6.3%、59.8%±5.9%(P<0.05)。间接免疫荧光定位检测发现氧化型低密度脂蛋白显著抑制RAW264.7细胞中亲环素A在胞膜、胞浆中的表达,且随着处理时间的延长作用更明显。细胞内胆固醇酯/总胆固醇的比值由未处理组的28.3%±1.2%上升至48 h的42.3%±5.9%(P均<0.05)。结论氧化型低密度脂蛋白诱导的RAW264.7巨噬细胞泡沫化过程中,亲环素A的表达下调与细胞胆固醇蓄积密切相关。     

亲环素A在巨噬细胞荷脂过程中的表达及普罗布考干预的影响

目的观察亲环素A在氧化型低密度脂蛋白诱导的巨噬细胞荷脂过程中的表达变化及其与细胞内胆固醇蓄积的关系,进而探讨亲环素A在动脉粥样硬化形成中的作用机制。方法采用75 mg/L氧化型低密度脂蛋白与RAW264.7巨噬细胞共同孵育,建立巨噬细胞荷脂化模型,油红O染色观察细胞内脂滴的形成,高效液相色谱法检测细胞内胆固醇含量,Western-blot检测亲环素A的蛋白表达;用75 mg/L普罗布考干预对上述检测的影响。结果氧化型低密度脂蛋白与RAW264.7细胞共同孵育48 h后,油红O染色显示细胞内有大量脂滴形成,细胞内总胆固醇和游离胆固醇含量均明显增加,胆固醇酯/总胆固醇的比值为42.3%±5.9%,符合荷脂细胞特征;亲环素A的蛋白表达明显减弱。予普罗布考处理,细胞内脂滴明显减少,胆固醇酯/总胆固醇的比值降至32.9%±2.5%,亲环素A的蛋白表达增加81.3%±3.6%,较对照组差异有显著性(P均<0.05)。结论氧化型低密度脂蛋白诱导的RAW264.7巨噬细胞荷脂过程中,亲环素A表达下调,促进细胞胆固醇蓄积;普罗布考干预可上调亲环素A蛋白表达,减轻细胞内的胆固醇蓄积。     

葡萄糖对THP-1源性巨噬细胞酰基辅酶A:胆固醇酰基转移酶1表达的影响

研究葡萄糖对人THP-1单核分化巨噬细胞酰基辅酶A：胆固醇酰基转移酶1（ACAT-1）表达的影响。发现高糖作用下，巨噬细胞ACAT-1的mRNA及蛋白表达增加，这可能是糖尿病血管病变机制之一。     

普罗布考对体内巨噬细胞胆固醇逆转运的作用

目的 测定不同剂量普罗布考干预后小鼠体内胆固醇逆转运效率,探讨普罗布考影响小鼠体内胆固醇逆转运的机制.方法 32只C57BL/6小鼠随机分为4组,给予不同剂量普罗布考(0,0.1％,0.5％,1.0％ W/W)添加饲料饲养4周后,腹腔注射经ac-LDL及3 H-胆固醇处理过的RAW264.7小鼠巨噬细胞悬液,48小时后测定粪便3H-胆固醇含量;提取肝脏和小肠组织RNA及细胞膜蛋白,分别检测肝脏胆固醇7 α-羟化酶、B族Ⅰ型清道夫受体(SR-B I)和ABCG5及小肠ABCG5基因与蛋白的表达.结果 普罗布考干预各组(0.1％,0.5％,1.0％)小鼠粪便中3H的总含量显著增多;0.5％与1.0％普罗布考两组之间差异无统计学意义.普罗布考干预后肝脏胆固醇7α-羟化酶、ABCG5 mRNA呈剂量依赖性地表达增多;肝脏、小肠ABCG5 mRNA及其蛋白呈剂量依赖性地表达增加;0.5％与1.0％普罗布考两组之间差异无统计学意义.普罗布考干预后肝脏SR-B Ⅰ的mRNA与蛋白表达没有明显变化.结论 普罗布考剂量依赖性地促进小鼠体内巨噬细胞的胆固醇逆转运,其机制可能是通过上调肝脏胆固醇7α-羟化酶、肝脏和小肠ABCG5的表达.     

胆固醇与骨质疏松

流行病学研究表明骨质疏松症发病风险与心血管疾病发病率之间具有正相关,高胆固醇血症对骨质疏松症的发生起重要作用。血清胆固醇、低密度脂蛋白胆固醇水平升高可导致骨密度下降,促进骨质疏松症的发生。破骨细胞和成骨细胞是维持骨动态平衡主要的骨代谢细胞,而胆固醇对骨代谢细胞的功能有重要影响。本文主要综述胆固醇和他汀类降胆固醇药物对成骨细胞和破骨细胞分化、形成及活性的影响,旨在为骨质疏松症的防治提供新的思路。     

Cholesterol and coronary heart disease mortality

The epidemiological relation between increased levels of blood cholesterol and increased risk of future heart disease is clear, both within and between countries. These strong relationships have led to the adoption of consensus statements in most countries which recommend measures such as the reduction of dietary saturated fat/an increase in the polyunsaturated/saturated ratio and other dietary and sometimes drug methods to reduce serum cholesterol. There is controversy as to whether these measures should be targeted at individuals with high levels of cholesterol or whether there should be a public health approach to the whole population. The public and medical debate has become more heated since the data from intervention trials are conflicting. Taken overall the trials do appear to show reduction in risk of coronary which is stronger for non fatal, compared with fatal coronary events. Meta analysis suggests that increasing benefit accrues from larger reductions and also longer reductions in cholesterol by intervention. However, individual trials frequently show variable results and some, especially the recent 15 year follow up of a Finnish five year intervention (by diet, cholesterol lowering and blood pressure lowering drugs) was strikingly adverse—although the total number of events was not large. Total mortality is much harder to influence and the sum of the available trials is hopelessly inadequate in size to address these questions. As a result confusion abounds and is unlikely to be clarified by the present on going trials. The need for more data is clear. The pilot study for the Oxford Cholesterol Study will be presented as a prelude for a proposed main study in about 20 000 high risk individuals.     

Cholesterol levels in patients with multiple myeloma

Hypocholesterolemia is seen in solid tumors and some hematological malignancies. We assessed cholesterol levels and the relationship between these levels and types and stages of multiple myeloma (MM) in the patients with MM. One-hundred two patients (60 male and 42 female) of mean age 59 ± 11 years with MM were enrolled to this study. While 71.6% of the patients were Ig G type, 80.4% of the patients were at stage III. In the control group, there were 71 healthy persons (42 male and 29 female) of mean age 58 ± 8 years. The levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) in the patients with MM were significantly lower than the controls (p < 0.001). There was no difference for the levels of very-low-density lipoprotein cholesterol and triglyceride between the two groups (p > 0.05). Lipid parameters were not different between Ig types (p > 0.05). The levels of TC and LDL-C in the patients with stage I were higher than those of stages II and III (p < 0.001 and p < 0.005, respectively). The levels of TC and LDL-C in the controls were not higher than the patients with stage I (p > 0.05). HDL-C levels in the patients with stage III were lower than controls (p < 0.001). Hypocholesterolemia are seen in the patients with MM. Hypocholesterolemia may be due to increased LDL clearance and utilization of cholesterol by myeloma cells. We did not receive any financial support, and this study has not been published in any journal.     

胆固醇代谢与阿尔茨海默病关系的研究进展

在阿尔茨海默病(AD)发病机制中,占主导地位是Aβ瀑流学说:由于淀粉样前体蛋白的代谢紊乱,产生了过量的Aβ42,后者迅速聚集形成寡聚物,启动了Aβ瀑流效应,造成了Aβ的沉积,形成老年斑.越来越多的实验表明,胆固醇在Aβ的产生和异常沉积过程具有重要调节作用,同时Aβ对胆固醇调节也有反馈作用,探讨两者的相互作用和影响有助于AD发病机制的阐明.而与胆固醇代谢密切相关的因素,如载脂蛋白E、调节胆固醇代谢的药物等也成为研究的热点.     

Cholesterol and cardiovascular disease: basic science

Cholesterol is a normal constituent of blood plasma and of cell membranes in every tissue of the body. It is transported in plasma as a component of lipoproteins. Increased concentrations of specific lipoprotein fractions, namely low density lipoproteins (LDL) and intermediate density lipoproteins (IDL), have been implicated both in vitro and in vivo as causes of atherosclerosis. The mechanism by which these lipoproteins initiate atherosclerosis is unknown, although there is growing evidence that it involves interactions between lipoproteins and cells within the artery wall, setting in train complex reactions which lead ultimately to the fully developed lesion.     

从胆固醇代谢标志物视角分析高脂血症患者血脂异常的影响因素

目的分析胆固醇吸收与合成标志物及其它相关指标对高脂血症患者血脂成份的影响,探讨高脂血症患者胆固醇代谢特点。方法选取高脂血症患者(n=53)和健康对照者(n=50),常规检测肝肾功能及血脂水平,应用气相色谱法检测胆固醇吸收与合成标志物水平。结果高脂血症组总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDLC)显著高于健康对照组(P0.05);高脂血症组角鲨烯、7-烯胆烷醇的合成率均高于健康对照组(P0.05),而豆固醇吸收率低于健康对照组(P0.05)。多元线性逐步回归分析显示,高脂血症组影响TC的独立影响因素为LDLC和菜油固醇,影响TG的独立影响因素为脱氢胆固醇和LDLC,影响健康对照组TC和TG的独立影响因素均为LDLC和7-烯胆烷醇。结论高脂血症患者胆固醇代谢标志物特点是角鲨烯、7-烯胆烷醇合成率显著增高,植物固醇中豆固醇吸收率显著降低;高脂血症组影响TC和TG的独立影响因素除LDLC外,还与胆固醇合成标志物(脱氢胆固醇)、胆固醇吸收标志物(菜油固醇)有关。     

血浆脂蛋白在胆囊胆固醇结石形成中的作用研究

目的：探讨血浆脂蛋白在胆囊胆固醇结石形成中的作用。方法：用常规生化方法分别测定了56例胆囊胆固醇结石及24例非胆石对照患者血清总胆固醇（TC）、甘油三酯（TG）、高密度脂蛋白（HDL）,低密度脂蛋白（LDL）的含量。结果：胆石组血清TC、HDL、LDL以及TG／TC比值均与对照组有显著性差异（P＜0．01或P＜0．05）。并且胆囊胆固醇结石组血清TG与TG／TC比值呈显著正相关关系。结论：本实验结果提示：血浆脂蛋白的变化,可能因影响体内的胆固醇及胆汗酸等代谢而与胆囊胆固醇结石的形成密切相关,TC、TG的测定及TG／TC比值可以作为间接反映胆囊胆固醇结石成核的参考指标。     

Cholesterol Exchange and Lateral Cholesterol Pools in Synaptosomal Membranes of Pair-Fed Control and Chronic Ethanol-Treated Mice

Most studies on effects of ethanol on membrane cholesterol have reported on changes in the total or bulk amount of cholesterol. Membrane cholesterol, however, can be described in terms of its kinetics and domains. The kinetics and size of lateral cholesterol exchangeable and nonexchangeable pools were examined in synaptosomes of pair-fed controls and chronic ethanol-treated mice. Effects of sphingomyelin, an exofacial leaflet phospholipid, that has been shown to affect cholesterol pools, were also examined. Radiolabeled small unilamellar vesicles were used to exchange cholesterol with synaptosomes. The total amounts of membrane cholesterol, phospholipid phosphorus, and the ratio of cholesterol to phospholipid did not differ between the pair-fed control and ethanol groups. In control mice, the rate constant (hr^-1) and the t_1/2 (hr) of cholesterol exchange were 0.065 ± 0.001 and 10.7 ± 0.25 (hr), respectively. The rate constant was significantly slower (0.053 ± 0.001, p < 0.05) and the t_1/2 significantly longer (13.33 ± 0.58, p < 0.05) in synaptosomes of the ethanol group compared with the control group. The size of the exchangeable pool of cholesterol did not differ significantly between the two groups. Sphingomyelinase-induced hydrolysis of sphingomyelin significantly slowed cholesterol exchange with the largest effect in synaptosomes of the control group as compared with the ethanol group ( p < 0.05). Hydrolysis of sphingomyelin had significantly ( p < 0.05) less of an effect on cholesterol exchange in synaptosomes of the ethanol group. Membrane cholesterol can be described in terms of total content, transbilayer distribution, kinetics, and size of lateral pools. This study supports the general hypothesis, that not all properties or domains of membrane cholesterol are equally affected by ethanol.