嘌呤霉素敏感的氨肽酶对β-淀粉样蛋白诱导的细胞凋亡的影响

目的 探讨嘌呤霉素敏感的氨肽酶(PSA)对β-淀粉样蛋白(Aβ25-35)诱导的SH-SY5Y细胞、PC12细胞凋亡的影响. 方法 采用MTT法检测Aβ25-35对SH-SY5Y、PC12细胞生长的影响;Hoechst染色检测Aβ25-35对SH-SY5Y、PC12细胞核形态的影响;进一步采用脂质体转染法在SH-SY5Y细胞中瞬时转染PSA-siRNA,在PC12细胞中瞬时转染PSA重组质粒,加入Aβ25-35作用24h后收集细胞,进行流式细胞术检测细胞凋亡率;Western blotting检测PSA、caspase-3蛋白的表达变化;酶标仪检测caspase-3活性. 结果 Aβ25-35抑制SH-SY5Y、PC12细胞增殖,细胞核发生凋亡的形态学改变,流式检测细胞凋亡率增加;在SH-SY5Y细胞中,沉默PSA表达能使Aβ25-35诱导的细胞凋亡率升高,促进caspase-3酶原激活,caspase-3活性升高.反之,PC12细胞中过表达的PSA能使Aβ25-35诱导的细胞凋亡率下降,抑制caspase-3酶原激活,caspase-3活性降低. 结论 Aβ25-35能抑制神经细胞生长,引起神经细胞凋亡;PSA能抑制Aβ25-35诱导的神经细胞凋亡,对神经元具有保护作用,其机制可能与抑制caspase-3通路的激活有关.     

SH-SY5Y神经细胞中α7神经型尼古丁受体基因沉默对CaM、CaMKⅡ蛋白水平的影响

目的构建稳定的α7 n AChR沉默的神经母细胞瘤细胞(SH-SY5Y)细胞,研究α7神经型尼古丁受体(n AChR)基因沉默对钙调蛋白(Ca M)、钙调素依赖性蛋白激酶Ⅱ(Ca MKⅡ)水平的影响,了解α7 n AChR神经保护作用及其与阿尔茨海默病(AD)发病机制的关系。方法将α7 n AChR shRNA重组质转染到SH-SY5Y,用含嘌呤霉素的培养液筛选,挑选阳性克隆后采用实时荧光定量PCR和蛋白质印迹方法(Western-blot)检测细胞中α7n AChR mRNA及蛋白表达水平的变化;Western-blot方法测定Ca M、Ca MKⅡ蛋白表达水平。结果获得稳定转染α7 n AChR shRNA重组质粒的细胞克隆株,与对照组相比,α7 n AChR mRNA及蛋白表达量分别减少了95%和80%。Ca M、Ca MKⅡ蛋白表达量分别减少了48.5%和35%。结论成功构建了α7 n AChR mRNA沉默的SH-SY5Y细胞细胞株,α7 n AChR沉默降低了Ca M、Ca MKⅡ的蛋白水平,可能影响信号通路转导,这可能与阿尔茨海默病(AD)的发病有一定的关系。     

稳定表达人野生型淀粉样前体蛋白细胞模型的建立与鉴定

目的 建立和鉴定稳定表达人野生型淀粉样前体蛋白(APP)的人神经母细胞瘤细胞系SH-SY5Y细胞模型.方法 脂质体转染法将含人野生型APP751 cDNA的真核表达质粒pcDNA3/APP APP751WT转染至SH-SY5Y细胞,G418对转染后细胞进行筛选,获得稳定表达人野生型APP751细胞模型.Western blotting法、MTT比色法和放射免疫法检测细胞APP表达水平、细胞生长情况和细胞内外β-淀粉样蛋白(Aβ)表达水平.结果 转染组细胞APP表达水平明显高于未转染组和空载体组.未转染组和空载体组细胞滞留期为12 h,对数生长期为12 h-4 d;转染组细胞滞留期为24h,对数生长期为1～4d;培养12 h后,转染组细胞活力低于未转染组和空载体组(t=4.363,P=0.0012;t=4.040,P=0.003),培养1 d后,转染组细胞活力降低,且低于未转染组和空载体组(t=4.736,P=0.001;t=4.317,P=0.005),其余各时间点差异均无统计学意义(P>0.05).转染组细胞细胞外Ap表达水平高于未转染组和空载体组(t=7.690,P=0.000;t=7.448,P=0.000),而3组细胞细胞内A8表达水平则差异无统计学意义(P>0.05).结论 成功建立稳定表达人野生型APP751的人神经母细胞瘤细胞系SH-SY5Y细胞模型,为进一步研究阿尔茨海默病的发病机制提供了良好的细胞模型.     

加兰他敏抗β淀粉样蛋白的神经保护机制研究

目的观察加兰他敏(Gal)对β淀粉样蛋白(Aβ)损伤人神经母细胞瘤细胞(SH-SY5Y)后β淀粉样前体蛋白(APP)代谢通路的影响,探讨Gal的神经保护机制。方法采用5μMAβ_(1-40)作用于SH-SY5Y细胞制备体外细胞损伤模型,0.3μM加兰他敏对Aβ_(1-40)处理的细胞进行干预并与正常细胞进行对照研究。倒置显微镜下观察细胞形态,应用噻唑蓝比色法(MTT)检测细胞活力,Western-blot技术定量检测各组APP,sAPPα,β-淀粉样前体蛋白剪切酶-1(BACE1)表达水平。结果 Aβ_(1-40)孵育细胞24h之后,细胞损伤明显,存活率从95.78.±2.5%降到62.93±2.1%,与对照组相比差异显著(P0.01);Western-blot显示细胞内BACE1表达增加,APP表达无明显改变,细胞分泌sAPPα降低;在Aβ_(1-40)孵育之前给予加兰他敏作用24h,细胞损伤程度减轻,细胞的存活率上升(85.26±5.3%)(P0.01),细胞内BACE1表达较Aβ组下降,APP表达无明显改变,细胞分泌sAPPα升高。结论加兰他敏通过抑制Aβ_(1-40)诱导的APP的异常代谢发挥神经保护作用。     

SH-SY5Y神经细胞中α7神经型尼古丁受体基因过表达对CaMK Ⅱ和CREB的影响

目的研究SH-SY5Y神经细胞中α7 nAChR基因过表达对CaMKⅡ和CREB的影响。方法复苏稳定转染α7 nAChR-pc DNA3.1质粒及空载质粒的SH-SY5Y神经细胞后,用含G418的培养液进行筛选培养;应用实时荧光定量PCR法和蛋白印迹法(Western blot)检测α7 nAChR基因过表达组、空载质粒组和正常对照组细胞中CaMKⅡ、CREB mRNA及蛋白表达水平的变化。结果与对照组相比,α7 nAChR基因过表达细胞组的CaMKⅡ、CREB mRNA表达水平分别增加了116.8%和114.7%(P0.01);及CaMKⅡ、CREB蛋白表达水平分别增加了8.7%(P0.05)和41.4%(P0.05)。结论α7 nAChR的神经保护作用可能与上调细胞CaMKⅡ、CREB水平有关。     

α3神经型尼古丁受体基因上调对SH-SY5Y细胞突触素水平的影响

目的构建使α3nAChR基因上调的重组质粒α3nAChR-pcDNA3.1并转染至神经母细胞瘤细胞(SH-SY5Y),研究α3nAChR基因上调对细胞突触素(SYP)水平的影响。方法设计α3nAChR上下游引物,通过逆转录PCR的方法获取人α3nAChR特异核苷酸序列,并将其克隆到质粒载体pcDNA3.1上,构建重组质粒α3nAChR-pcDNA3.1;瞬时转染至SH-SY5Y细胞后,用Real-time法和蛋白免疫印迹法分别α3nAChR及蛋白水平,并检测上调细胞中SYPmRNA和蛋白水平的变化。结果成功构建了使α3nAChR基因上调的重组质粒α3nAChRpcDNA3.1;将α3nAChR-pcDNA3.1质粒转染到SH-SY5Y细胞后,与空载质粒组及正常对照组相比,α3nAChRmRNA及蛋白表达水平分别增加了422%和106%(P0.05);SYPmRNA及蛋白表达水平分别增加了115%和43%(P0.05)。结论α3nAChR表达的上调可使细胞SYP的表达增加,说明了α3nAChR与SYP密切相关,在AD的发生中可能起着重要作用。     

MicroRNA-9靶向BACE1参与Alzheimer病发生发展的机制研究

目的 探讨microRNA-9(miR-9)靶向BACE1参与Alzheimer病(AD)发生发展的机制。方法 选取2013年5月-2015年5月解放军第161医院收治的AD患者23例,以血管性痴呆(Vascular dementia,VD)21例和颅内感染患者(intracranial infection,ICI)20例为对照组,比较3组患者脑脊液中miR-9、BACE1和APP的表达水平; 然后用荧光素酶报告系统验证miR-9与BACE1之间的靶向关系; 最后将miR-9 mimics转染入SH-SY5Y 细胞,qRT-PCR和Western Bolt检测BACE1和APP的mRNA和蛋白表达水平。结果 与VD和ICI组比较,AD患者脑脊液中miR-9表达水平下降,BACE1和APP表达水平增高,AD患者脑脊液中miR-9表达水平与BACE1表达水平呈负相关; BACE1为miR-9的功能靶基因; miR-9可靶向BACE1参与调控SH-SY5Y细胞APP表达。结论 miR-9可靶向BACE1参与AD的发生发展。     

SH-SY5Y细胞α7神经型尼古丁受体基因沉默对突触相关蛋白的影响

目的研究神经母细胞瘤细胞(SH-SY5Y)α7神经型尼古丁受体基因(α7 nAChR)表达沉默后对细胞突触相关蛋白的影响,探讨α7 nAChR神经保护作用机制及在阿尔茨海默病(Alzheimer disease,AD)的发病机制中的作用。方法用Real-time PCR法和蛋白免疫印迹(Western blot)法分别测定细胞中囊泡相关蛋白(synaptophysin)和突触后膜蛋白(PSD-95)mRNA蛋白表达水平的变化。结果α7 nAChR沉默组的突触相关蛋白PSD-95、SYPmRNA及蛋白表达都有明显的减少。结论沉默SH-SY5Y细胞α7 nAChR水平能够使细胞突触相关蛋白水平减少。这可能提示了α7 nAChR与细胞突触密切相关,并且α7 nAChR对突触有一定的保护作用,进一步说明α7nAChR在阿尔茨海默病的发病中起着重要作用。     

AGEs对SH-SY5Y细胞增殖、凋亡以及阿尔茨海默病相关mRNA的影响

目的 研究晚期糖基化终产物(AGEs)对人神经母细胞瘤SH-SY5Y细胞株增殖、凋亡以及AD相关mRNA的影响。 方法 利用小牛血清白蛋白(BSA)和葡萄糖体外制备BSA-AGEs;将SH-SY5Y细胞与不同浓度BSA-AGEs保温后,MTT法测定SH-SY5Y细胞的增殖率,流式细胞仪测定细胞凋亡和细胞周期的变化,RT-PCR检测细胞中AD相关mRNA的表达水平。 结果 BSA-AGEs对SH-SY5Y细胞增殖有明显抑制作用,明显促进神经元的凋亡,细胞周期被阻滞于G1/G0期,呈药物浓度依赖性。RT-PCR结果表明,经过BSA-AGEs刺激后,IL-6、高迁移率族蛋白B1(HMGB1)、淀粉先质蛋白(APLP1) mRNA表达水平均明显升高。 结论 BSA-AGEs能有效抑制SH-SY5Y细胞的增殖,促进炎症细胞因子产生,诱导细胞凋亡,提示AGEs在AD的发生与发展过程中具有促进作用。     

突变型APP双荧光融合基因的构建和FRET对其表达的研究

目的探讨Alzheimer病的发病机制,研究淀粉样蛋白前体(APP)酶解过程,构建含有Swedish突变的双荧光真核表达系统。方法通过聚合酶链式反应(PCR)得到蓝色荧光蛋白(CFP)和黄色荧光蛋白碱基序列(YFP),生物合成含有Swedish突变的APP中间54个碱基片段(54bp),利用基因工程技术将CFP、54bp、YFP片段克隆至载体质粒pcDNA3.0中,得到重组质粒pcDNA3.0-CFP-54bp-YFP,将其转染至人神经母细胞瘤细胞(SH-SY5Y)中,利用激光共聚焦显微镜观察荧光表达,检测荧光共振能量转移(FRET)。结果酶切和基因序列分析证明重组质粒构建成功;对转染细胞的荧光和FRET检测发现融合基因能够准确表达荧光,同时可以观测到FRET现象。结论含有Swedish突变的荧光融合基因的构建为探索AD的发病机制、活体观察APP裂解奠定了基础。     

Effects of geroprotective peptides on the activity of cholinesterases and formation of the soluble form of the amyloid precursor protein in human neuroblastoma SH-SY5Y cells

Age related decline of cognitive functions in humans is a result of degeneration of cholinergic neurones and acetylcholine deficit in certain brain structures. In this connection, inhibitors of cholinesterases capable of preventing further decline of acetylcholine levels are widely used for treatment of cognitive disorders, in particular in Alzheimer’s disease (AD). Despite a wide range of anticholinesterase drugs available to date most of them have side-effects and are not always beneficial in older patients. Moreover, there are two forms of cholinesterases, namely acetyl- and butyrylcholinesterases (AChE and BuChE) which have different levels of their expression, localisation and functions in the brain. Since with age there is a decrease of AChE activity and an increase of BuChE, the design of selective inhibitors for each enzyme is required. In the present work the effects of synthetic geroprotective peptides vilon (Lys-Glu) and epithalon (Ala-Glu-Asp-Gly) on the activity of AChE and BuChE in human neuroblasoma cells SH-SY5Y have been studied. Also we performed an analysis of the effects of these peptides on the activity of the α-secretase of amyloid precursor protein (APP) which participates in non-amyloidogenic processing of APP releasing a soluble fragment of APP, and possibly in formation of a soluble form of AChE. It was found that incubation of cells during 24 hours in the presence of 50 nM of vilon and epithalon resulted in a decrease of the activity of soluble and membrane-bound forms of AChE and BuChE on average by 30–60%. Both peptides mostly inhibited membrane-bound forms of the enzymes but to a greater extent BuChE. Epithalon was also found to be capable of activation of α-secretase by 20–25%. The data obtained suggest that vilon and epithalon have selective anticholinesterase properties and that epithalon can also stimulate APP cleavage and increase production of its soluble neuroprotective form.     

miR-15b对MPP+损伤SH-SY5Y细胞中α突触核蛋白表达的影响

目的研究miR-15b对MPP+(1-甲基-4-苯基-吡啶离子)损伤SH-SY5Y细胞中α突触核蛋白表达的影响以及在帕金森病(Parkinson disease,PD)发病机制中的作用。方法通过CCK-8检测出MPP+诱导SH-SY5Y细胞为PD细胞模型的最适浓度和时间,然后将过表达和沉默miR-15b的质粒转染到PD细胞模型内,再通过Real Time-PCR和Western Blot检测miR-15b和α突触核蛋白的表达量。结果 SH-SY5Y细胞经MPP+诱导后细胞形态发生改变、细胞增殖能力降低,过表达miR-15b后α-synuclein和α突触核蛋白的表达量均降低(P 0. 05),沉默miR-15b后α-synuclein和α突触核蛋白的表达量均升高(P 0. 05)。结论 miR-15b可以抑制PD细胞模型内α-synuclein和α突触核蛋白的表达。miR-15b可能参与了帕金森病患者中脑黑质多巴胺能神经元内α突触核蛋白的富集调节机制。     

Short- and long-term effect of acetylcholinesterase inhibition on the expression and metabolism of the amyloid precursor protein

We have investigated the acute and chronic effect of metrifonate (MTF) and dichlorvos (DDVP), respectively the prodrug and active acetylcholinesterase inhibitor, on the secretory processing of the amyloid precursor protein (APP) in SH-SY5Y neuroblastoma cells. We demonstrate that the acute treatment of SH-SY5Y cells with both compounds results in an increased secretion of the soluble fragment of APP (sAPPalpha) into the conditioned media of cells, with a pattern correlated to the level of acetycholinesterase inhibition. The regulation of APP processing in these conditions is mediated by an indirect cholinergic effect on muscarinic receptors, as demonstrated by inhibition with atropine. We have also followed APP expression and metabolism after long-term treatment with metrifonate. Treated cells showed reduced AChE activity after 24, 48 h and also following 7 days of repeated treatment, a time point at which increased AChE expression was detectable. At all time points sAPPalpha release was unaffected suggesting that enhanced sAPPalpha release by MTF is transitory, nevertheless the sensitivity of cholinergic receptors was unchanged, as indicated by the fact that cholinergic response can be elicited similarly in untreated and treated cells. APP gene expression was unaffected by long-term AChE inhibition suggesting that increased short-term sAPPalpha release does not elicit compensatory effects.     

Chemokine receptor 4 gene silencing blocks neuroblastoma metastasis in vitro

This study investigated the effects of small interfering RNA （siRNA）-mediated silencing of chemokine receptor 4 （CXCR4） on the invasion capacity of human neuroblastoma cell line SH-SY5Y in vitro. Three siRNAs targeting CXCR4 were chemically synthesized and individually transfected into SH-SY5Y cells. Expression of CXCR4 mRNA and protein was signiifcantly sup-pressed in transfected cells by all three sequence-speciifc siRNAs compared with control groups. Furthermore, the invasion capacity of SH-SY5Y cells was signiifcantly decreased following trans-fection with CXCR4-speciifc siRNA compared with the control groups. These data demonstrate that down-regulation of CXCR4 can inhibit in vitro invasion of neuroblastoma.     

Effects of Edaravone on Amyloid-β Precursor Protein Processing in SY5Y-APP695 Cells

Previous reports have revealed that reactive oxygen species (ROS) is involved in the development of Alzheimer’s disease (AD), and recent studies indicate that free radical-generating systems can regulate amyloid-β precursor protein (APP) processing. Edaravone is a novel free radical scavenger currently used to reduce cerebral damages after acute cerebral infarction. In the present study, we used SH-SY5Y cells stably transfected with the human “Swedish” APP mutation APP695 (SY5Y-APP695swe) as an in vitro model to investigate the effect of edaravone on APP processing. The result showed that edaravone treatment for 24 h down-regulated β-amyloid (Aβ) production in a dose-dependent manner. Moreover, edaravone modulated APP processing by increasing α-secretase-derived APP fragments and decreasing β-secretase-derived APP fragments. In addition, the mRNA and protein levels of insulin degrading enzyme (IDE) and neprilysin (NEP), two key Aβ degrading enzymes, were not changed after edaravone administration. Taken together, our data suggested that edaravone played an important role in regulating Aβ production by enhancing the non-amyloidogenic pathway and inhibiting the amyloidogenic pathway. Thus, edaravone may be potentially useful for treating Alzheimer’s disease (AD).     

Comparative study of the expression of cholinergic system components in the CNS of experimental autoimmune encephalomyelitis mice: Acute vs remitting phase

Acetylcholine (ACh) is involved in the modulation of the inflammatory response. ACh levels are regulated by its synthesizing enzyme, choline acetyltransferase (ChAT), and by its hydrolyzing enzymes, mainly acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). A more comprehensive understanding of the cholinergic system in experimental autoimmune encephalomyelitis (EAE) disease progression could pave the path for the development of therapies to ameliorate multiple sclerosis (MS). In this work, we analyzed possible alterations of the CNS cholinergic system in the neuroinflammation process by using a MOG‐induced EAE mice model. MOG‐ and vehicle‐treated animals were studied at acute and remitting phases. We examined neuropathology and analyzed mRNA expression of ChAT, AChE and the α7 subunit of the nicotinic acetylcholine receptor (α7nAChR), as well as AChE and BuChE enzyme activities, in brain and spinal cord sections during disease progression. The mRNA expression and enzyme activities of these cholinergic markers were up‐ or down‐regulated in many cholinergic areas and other brain areas of EAE mice in the acute and remitting phases of the disease. BuChE was present in a higher proportion of astroglia and microglia/macrophage cells in the EAE remitting group. The observed changes in cholinergic markers expression and cellular localization in the CNS during EAE disease progression suggests their potential involvement in the development of the neuroinflammatory process and may lay the ground to consider cholinergic system components as putative anti‐inflammatory therapeutic targets for MS.     

Hypercholesterolemia induces short-term spatial memory impairments in mice: up-regulation of acetylcholinesterase activity as an early and causal event?

Epidemiological studies have indicated hypercholesterolemia in midlife as a risk factor for dementia in later life, bringing cholesterol to the forefront of Alzheimer’s disease research. Herein, we modeled mild hypercholesterolemia in mice to evaluate biochemical and behavioral alterations linked to hypercholesterolemia. Swiss mice were fed a high fat/cholesterol diet (20 % fat and 1.25 % cholesterol) for an 8-week period (from 12 to 18 weeks old) and were tested on the object location, forced swimming and elevated plus-maze tasks. We also investigated hypercholesterolemia-induced changes on acetylcholinesterase (AChE) activity, oxidative damage, amyloid precursor protein (APP) processing and blood brain barrier (BBB) integrity within the prefrontal cortex and hippocampus. It was found that increased AChE activity within the prefrontal cortex and hippocampus is an early event associated with hypercholesterolemia-induced short-term memory impairments. We observed no signs of antioxidant imbalance and/or oxidative damage or changes in cortical and hippocampal densities of beta-site amyloid precursor protein-cleaving enzyme 1 and aquaporin-4, biomarkers of APP processing and BBB integrity, respectively. In addition, we treated SH-SY5Y human neuroblastoma cells with low-density lipoprotein (LDL) cholesterol in an attempt to manipulate cell cholesterol content. Notably, LDL cholesterol increased in a dose-dependent manner the activity of AChE in SH-SY5Y cells. The present findings provide new evidence that increased AChE activity within the prefrontal cortex and hippocampus is an early event associated with hypercholesterolemia-induced cognitive impairments.