Targeting β-secretase with RNAi in neural stem cells for Alzheimer's disease therapy

There are several major pathological changes in Alzheimer＇s disease, including apoptosis of cho- linergic neurons, overactivity or overexpression of 13-site amyloid precursor protein cleaving enzyme 1 （BACE1） and inflammation. In this study, we synthesized a 19-nt oligonucleotide targeting BACE1, the key enzyme in amyloid beta protein （AI3） production, and introduced it into the pSilenCircle vector to construct a short hairpin （shRNA） expression plasmid against the BACE1 gene. We transfected this vector into C17.2 neural stem cells and primary neural stem cells, resulting in downregulation of the BACE1 gene, which in turn induced a considerable reduction in reducing AI3 protein production. We anticipate that this technique combining cell transplantation and gene ther- apy will open up novel therapeutic avenues for Alzheimer＇s disease, particularly because it can be used to simultaneously target several pathogenetic changes in the disease.

Influence of Ginkgo Biloba extract on beta-secretase in rat hippocampal neuronal cultures following chronic hypoxic and hypoglycemic conditions

BACKGROUND： Preparation of Ginkgo leaf has been widely used to improve cognitive deficits and dementia, in particular in Alzheirner＇s disease patients. However, the precise mechanism of action of Ginkgo leaf remains unclear. OBJECTIVE： To explore the effect of Ginkgo Biloba extract （Egb761）, Ginaton, on β -secretase expression in rat hippocampal neuronal cultures following chronic hypoxic and hypoglycemic conditions. DESIGN, TIME AND SETTNG： Completely by randomized, grouping study. The experiment was performed at the Laboratory of Molecular Imaging, Southeast University between August 2006 and August 2007. MATERIALS： A total of 128 Wistar rats aged 24 hours were selected, and hippocampal neurons were harvested for primary cultures. METHODS： On day 7, primary hippocampal neuronal cultures were treated with Egb761 （0, 25, 50, 100, 150, and 200μg/mL） under hypoxic/hypoglycemic or hypoglycemic culture conditions for 12, 24, and 36 hours, respectively. Hippocampal neurons cultured in primary culture medium served as control. MAIN OUTCOME MEASURES： Cell viability was assayed using 3-（4,5-Dimethylthiazol-2-yl）- 2,5-diphenyltetrazolium bromide （MTT）; fluorescence detection of β -secretase activity was performed; Western Blot was used to measure β -secretase expression. RESULTS： Cell viability under hypoxic/hypoglycemic or hypoglycemic culture conditions was significantly less than control cells （P 〈 0.05）. Under hypoxic/hypoglycemic or hypoglycemic culture conditions, treatment with 25 μg/mL Egb761 did not alter cell viability. However, 〉 25 μg/mL Egb761 induced greater cell viability （P 〈 0.05）. No differences were observed between hypoxic/hypoglycemic or hypoglycemic cells （P 〉 0.05）. α -secretase activity was increased after 12 hours in hypoxic/hypoglycemic culture （P 〈 0.01）. There were no significant differences between the 12-, 24-, or 36-hour Egb761 groups and the hypoxic/hypoglycemic groups （P 〉 0.05）. β -secretase activity was greater after 12, 24, and 36 hours in hypoxic/hypoglycemic culture conditions, compared with control conditions （P 〈 0.05）. β-secretase activity was significantly decreased in neurons treated with Egb761 for 12, 24, or 36 hours, compared with the hypoxichaypoglycemic group （P 〈 0.05）. β -secretase protein expression was significantly up-regulated in neurons cultured in hypoxic/hypoglycemic conditions for 12, 24, or 36 hours, compared to control cells （P 〈 0.05）, and was decreased compared to neurons treated with Egb761 （P 〈 0.05）. CONCLUSION： β -secretase expression and activity in rat neonatal hippocampal neurons were influenced by hypoxic and hypoglycemic culture. Egb761 played a protective role in hippocampal neurons damaged by chronic hypoxic and hypoglycemic culture conditions, possibly through its effect on β -secretase expression and activity.

Improving cognitive impairment by Tongxinluo via inhibiting expression of beta-secretase 1/beta-amyloid peptide in experimental vascular dementia

BACKGROUND： Tongxinluo has been clinically proven to be effective in improving memory and cognitive function in patients with post-stroke vascular dementia. Is the mechanism related to the deposition of beta-amyloid peptide （A β ） in hippocampus？ OBJECTIVE： To observe the effect of Tongxinluo on cognitive impairment in a mouse model with vascular dementia and the changes of A β deposition and β -secretase 1 （BACE1） expression. DESIGN： Randomized controlled study. SETTING： State Key Laboratory of Pharmaceutical Biotechnology of Nanjing University and Affiliated Drum Tower Hospital of Nanjing University Medical School. MATERIALS： The experiment was carried out in the State Key Laboratory of Pharmaceutical Biotechnology of Nanjing University and Affiliated Drum Tower Hospital of Nanjing University Medical School from March 2006 to January 2007. A total of 36 healthy Kunming mice, 18 of each gender, were chosen. The study was conducted in accordance with the National Regulations of Experimental Animal Administration, and all animal experiments were approved by the Committee of Experimental Animal Administration of Nanjing University. Tongxinluo was provided by Shijiazhuang Yiling Pharmaceutical Co., Ltd. METHODS： All mice were randomly divided into 6 groups, including naive control （n=6）, sham-operated control （n=6） and experimental groups treated with different doses of Tongxinluo （0.2, 0.4, and 0.6 g/kg/d; n=6 for each group） or vehicle （n=6）. Five groups were subjected to bilateral common carotid arteries （2-VO） occlusion to produce a vascular dementia model （no occlusion was performed in sham-operated group）. The mice in the Tongxinluo treatment groups were intragastricly administered daily with a Tongxinluo suspension （40 g/L in distilled water） at doses of 0.2, 0.4 or 0.6 g/kg/d from day 1 to day 30 post-surgery. The animals in vehicle, sham-operated and naive groups were administered an equal volume of distilled water. MAIN OUTCOME MEASURES： ①Escape latency time determined in all groups of mice before and after 2-VO occlusion by Morris water maze. ②Changes in BACEI mRNA expression in the hippocampi of mice among the six groups by RT-PCR assay, and BACEI and A β protein expression in the hippocampi of mice by Western blot. RESULTS： All 36 mice were involved in the final analysis.① No difference was detected in escape latency time to a hidden platform among all groups in water maze test before surgery （P 〉 0.05） At 30 days after 2-VO occlusion, the vehicle animals exhibited a significantly longer latency in finding the hidden platform compared to that of sham-operated and naive animals （P 〈 0.01）. The prolonged escape latency was significantly reduced by oral administration of 0.4 g or 0.6 kg/day （P 〈 0.01, P 〈 0.05）. BACEI mRNA and protein expression in vehicle animals were much higher than in sham-operated and naive animals （P 〈 0.01）. The ischemia-induced increases in BACE1 mRNA and protein level were attenuated by all three doses of Tongxinluo treatment （P 〈 0.01）, and the 0.4 g/kg/d treatment was the most effective. A β protein expression in vehicle animals after 2-VO occlusion were much higher than in sham-operated and naive animals （P 〈 0.01）. 2-VO occlusion-induced A β generation was significantly attenuated by all doses of Tongxinluo treatment, with the most effective dose being 0.4 g/kg/d （P 〈 0.01）. CONCLUSION： BACE1 mRNA levels and protein levels of BACEI and A β are reduced in the hippocampi of vascular dementia model mice by all three doses of Tongxinluo treatment, with the most effective dose being 0.4 g/kg/d. The results suggest that inhibition of post-ischemia BACEI expression and A β generation in brain might underlie Tongxinluo＇s effects in improving cognitive impairment.

Effects of chronic cerebral hypoperfusion of beta- and gamma-secretase on learning and memory in rats

BACKGROUND： Chronic cerebral hypoxia and ischemia have been shown to be related to occurrence of sporadic Alzheimer＇s disease, and β- and y-secretase play an important role in the generation of β-amyloid protein. Early clinical symptoms in Alzheimer＇s disease patients include learning and memory deficits. OBJECTIVE： To measure learning and memory, as well as β- and β-secretase activities in the hippocampus of a cerebral ischemia/hypoxia rat model with chronic cerebral hypoperfusion. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the Department of Pathology, Capital Medical University from March to December, 2008. MATERIALS： β- and y-secretase activity kits were purchased from R ＆ D Systems, USA. METHODS： Male Sprague Dawiey rats, aged 23 weeks, were randomly assigned to model （n = 56） and sham-surgery （n = 46） groups. Cerebral hypoperfusion rat models were established by bilateral common carotid occlusion. MAIN OUTCOME MEASURES： Morris water maze was used to test changes in escape latency and path length, and β- and y-secretase activities were measured on days 10, 30, 90, and 180 following surgery. RESULTS： Progressive cognitive impairment resulted from 30 days of chronic cerebral hypoperfusion, which lasted for 180 days after cerebral hypoperfusion. β-secretase activity was increased at 10 days after hypoperfusion, which continued until 180 days, with a 14.25% increase compared to the sham-surgery group; y-secretase activity was increased by 10.5%. CONCLUSION： Chronic cerebral hypoperfusion results in impaired spatial memory and upregulated β- and y-secretase activities, which could play an important role in β-amyloid production.

Pharmacological Assessment of <i>γ</i>-Secretase Activity from Rodent and Human Brain

γ-Secretase is involved in the final processing of the amyloid precursor protein into a heterogeneous pool of β-amyloid (Aβ) peptides. Current Alzheimer’s disease drug discovery efforts include targeting γ-secretase activity in brain to attenuate production of the neurotoxic Aβ species. The resulting pharmacology may be affected by species-specific differences in the γ-secretase core complex or its associated proteins. Therefore, we utilized partially purified γ-secretase membranes derived from the brains of different species, including human cortex, to quantitatively assess the de novo production of both Aβ42 and Aβ40 following treatment with known γ-secretase inhibitors and modulators. We determined that the inhibitory activity of a Notch-1 sparing γ-secretase inhibitor and the modulatory activity of two classes of γ-secretase modulators were equipotent at affecting the production of Aβ across rodent and human brain membrane preparations. Additionally, the observed modulator-specific Aβ profile in isolated brain membranes across species was similar to that observed in HeLa cell membranes, and the brain and CSF of guinea pigs following oral administration. By utilizing rapidly purified γ-secretase, we were able to probe and compare the complex pharmacology of γ-secretase in the brain across common rodent species and human cortex.

Design, Synthesize and Bio-Evaluate 1,2-Dihydroisoquinolin-3(4H)-One Derivates as Acetylcholinesterase and β-Secretase Dual Inhibitors in Treatment with Alzheimer’s Disease

With the recent research advances in molecular biology and technology, many credible hypothe-ses about the progress of Alzheimer’s disease (AD) have been proposed, among which the amyloid and cholinergic hypotheses are commonly used to develop reliable therapeutic agents. The multitarget-directed ligand (MTDL) approach was taken in this work to develop multi-functional agents, which can mainly serve as dual BACE 1 and AChE inhibitors. Depending on the scaffolds of (+)-(S)- dihydro-ar-tumerone and (-)-gallocatechin gallate, 3 series of new compounds have been designed, synthesized and evaluated, from which we have identified 2-(2-(3-methylbenzoyl)-3-oxo-1,2,3,4- tetrahydroisoquinolin-6-yl) isoindoline-1,3-dione (3d) as a new cholinesterase and β-secretase dual inhibitor without toxicity. Furthermore, 3d also exhibits hydrogen peroxide scavenging activity which could help to reduce the reactive oxygen species (ROS) in the brain of AD patients.

Purification of Full-Length <i>β</i>-Secretase Involved in Alzheimer’s Disease, and Proteomic Identification of Binding Partners

β-Secretase (BACE1 or β-site APP cleaving enzyme) is an acid protease that releases the neurotoxic 40 - 42 residue peptides (β-amyloid or A-β) from its glycoprotein precursor, (APP or amyloid precursor protein) which when released in brain is thought to give rise to cognitive decline in patients with Alzheimer’s Disease. Most structural studies on β-secretase have previously been performed with recombinant forms of the protease, in which the transmembrane coding region has been deleted. However, interactions with proteins of the same species are best studied using the full-length β-secretase as interactions are likely to be influenced by the hydrophobic nature and localization of its transmembrane regions. Here we develop a multi-step purification procedure that isolates a complex containing BACE1 from recombinant human cells using mild detergents in a procedure that retains other proteins within the complex and remains active in its β-site APP cleaving activity. Some of these proteins, eg reticulon 4, are identified by proteomics, and are known by previous studies performed by others to regulate the activity of BACE1 against APP. These interactions may aid the development of small proteins and peptides that could inhibit the release of aggregated forms of β-amyloid, and thus be useful therapeutically.

Precise location of proton of beta-secretase for catalytic aspartates(Asp 32 and Asp 228)in Alzheimer’s patients

BACKGROUND：β-secretase （β-site APP cleavage rate-limiting enzyme, BACE） has been proposed as a promising therapeutic target for Alzheimer＇s disease （AD）. BACE inhibition reduces production of β-amyloid peptide （Aβ） and promotes neural regeneration. Two catalytic aspartates （Asp 32 and Asp 228） exist in a monoprotonated state in the active BACE site, but the precise proton location remains unclear.OBJECTIVE：To explore the entire process of BACE enzymatic hydrolysis using quantum chemistry calculations, and to identify the precise proton location for Asp 32 and Asp 228 during the enzymatic process.DESIGN, TIME AND SETTING：According to protonation state of BACE, four tautomers were designed and quantum chemistry calculations were performed at the Department of Human Anatomy, Zhongshan School of Medicine, Sun Yat-sen University, China between October 2008 and March 2009.MATERIALS：Hardware：linux workstation （Department of Equipment, Sun Yat-sen University, China）; software：QSITE, Glide, Maestro （Schrodinger LLC, USA）, MOPAC 2007 （CAChe Research LLC, USA）, Triton 4.0 （National Centre for Biomolecular Research, Czech Republic） were used.METHODS：Using crystal structures of BACE to build a catalytic model （enzyme, catalytic water, and substrate peptide EVNLAAEF） on the computer and superimposition, four BACE tautomers （32i, 320, 228i, and 2280） in the monoprotonated state were developed with Schrodinger package. Hybrid quantum mechanical/molecular mechanic （QM/MM） calculations were performed at the B3LYP density functional theory level to identify the precise proton location for the dyad aspartic residues （Asp 32 and Asp 228）. Using the most possible tautomer as the reactant, the entire enzymatic hydrolysis of substrate EVNL/AAEF was simulated at the semiempirical level.MAIN OUTCOME MEASURES：The precise proton location of was measured by analyzing co-planarities of 4 BACE tautorners （32i, 32o, 228i, and 2280） in the monoprotonated state, because the dihedral formed by the carboxyl oxygen atoms of the dyad aspartic residues. The transition state and the production state, as well as activation energies and reaction enthalpies, were measured by calculating geometric and energy changes during catalytic reaction of the system.RESULTS：In the 2280 BACE tautomer, the dihedral angle of the four oxygen atoms in the catalytic aspartates was 8.7°, which was the lowest of four tautomers. The lowest activation energy and highest reaction enthalpy （Ea = 216.30 kJ/mol, AH = 30.98 kJ/mol） were also found in 2280, among the four tautomers during the catalytic reaction. In addition, when the reaction proceeded to the transition state, followed by product generation, the proton location was reversed to the inner oxygen of Asp 32 （32i） from the outer oxygen of Asp 228 （228o）.CONCLUSION：Results demonstrated the mechanism of Aβ generation. At beginning of BACE catalytic reaction, the precise proton location was preferred on the outer oxygen of Asp 228 （228o）. In this protonation state, catalytic reaction can proceed smoothly, with reduced active energy and heat release. When the reaction proceeded to the transition state and product generation, the proton location was reversed to the inner oxygen of Asp 32 （32i）. These results provide theoretical guidance for designing new drugs to protect neural cells and promote neural regeneration in Alzheimer＇s patients.

Divalent cation tolerance protein binds to β-secretase and inhibits the processing of amyloid precursor protein

The deposition of amyloid-beta is a pathological hallmark of Alzheimer＇s disease, Amyloid-beta is derived from amyloid precursor protein through sequential proteolytic cleavages by β-secretase （beta-site amyloid precursor protein-cleaving enzyme 1） and r-secretase. To further elucidate the roles of beta-site amyloid precursor protein-cleaving enzyme 1 in the development of AIzheimer＇s disease, a yeast two-hybrid system was used to screen a human embryonic brain cDNA library for proteins directly interacting with the intracellular domain of beta-site amyloid precursor protein-cleaving enzyme 1. A potential beta-site amyloid precursor protein-cleaving enzyme 1- interacting protein identified from the positive clones was divalent cation tolerance protein. Immunoprecipitation studies in the neuroblastoma cell line N2a showed that exogenous divalent cation tolerance protein interacts with endogenous beta-site amyloid precursor protein-cleaving enzyme 1. The overexpression of divalent cation tolerance protein did not affect beta-site amyloid precursor protein-cleaving enzyme 1 protein levels, but led to increased amyloid precursor protein levels in N2a/APP695 cells, with a concomitant reduction in the processing product amyloid precursor protein C-terminal fragment, indicating that divalent cation tolerance protein inhibits the processing of amyloid precursor protein. Our experimental findings suggest that divalent cation tolerance protein negatively regulates the function of beta-site amyloid precursor protein-cleaving enzyme 1. Thus, divalent cation tolerance protein could play a protective role in Alzheimer＇s disease.

金银花绿原酸对铝致阿尔茨海默病模型小鼠相关分泌酶、脂氧素A4和生化指标的影响

目的 探讨金银花绿原酸对铝致阿尔茨海默病(AD)小鼠相关分泌酶、脂氧素A4(LXA4)和血液生化指标的影响。方法 采用超声辅助醇提法提取金银花中绿原酸。将70只小鼠随机分为正常组,模型组及金银花绿原酸低、中、高剂量组,每组14只。除正常组外,其余组小鼠均采用麦芽酚铝腹腔注射染毒建立铝致AD模型,每连续注射5 d间歇2 d,共染毒8周。从染毒第5周开始,金银花绿原酸低、中、高剂量组分别给予金银花绿原酸溶液40 mg/kg、80 mg/kg、160 mg/kg灌胃,正常组和模型组灌喂等体积蒸馏水,均1次/d,连续灌胃至第8周末。实验结束,采用Y型水迷宫测定小鼠的学习记忆能力,记录小鼠达到学会标准时所需的测试次数、20次测试中的记忆错误次数和错误率。取小鼠大脑,酶联免疫吸附法测定脑组织匀浆中β-分泌酶、α-分泌酶、γ-分泌酶、LXA4和乙酰胆碱酯酶(AchE)含量,取血测定生化指标[血糖、总胆固醇(TC)、三酰甘油(TG)、高密度脂蛋白胆固醇(HDL-C)、总蛋白、丙氨酸氨基转移酶(ALT)、尿素氮(BUN)、肌酐(Cr)、尿酸(UA)]。结果 与正常组比较,模型组小鼠学习测试次数、记忆错误次数、错误率和脑组织中β-分泌酶、γ-分泌酶、AchE含量均明显升高(P均<0.05),脑组织中LXA4含量明显降低(P<0.05),α-分泌酶含量无明显变化(P>0.05);与模型组比较,金银花绿原酸各组小鼠学习测试次数、记忆错误次数、错误率和脑组织中β-分泌酶、γ-分泌酶、AchE含量均明显降低(P均<0.05),金银花绿原酸高剂量组脑组织中LXA4含量明显升高(P<0.05),金银花绿原酸各组脑组织中α-分泌酶含量无明显变化(P均>0.05)。与正常组比较,模型组血糖、TC、TG、ALT、BUN、Cr、UA水平和金银花绿原酸低、中剂量组TC、TG、BUN水平均明显升高(P均<0.05),模型组HDL-C水平和金银花绿原酸中、高剂量组UA水平均明显降低(P均<0.05);与模型组比较,金银花绿原酸各组血糖、ALT、BUN、UA水平和金银花绿原酸中、高剂量组TC、Cr水平及金银花绿原酸高剂量组TG水平均明显降低(P均<0.05),金银花绿原酸中、高剂量组HDL-C水平和金银花绿原酸高剂组总蛋白水平均明显升高(P均<0.05)。结论 金银花绿原酸可能通过调控相关分泌酶、LXA4和各生化指标而起到改善铝暴露致AD的作用。

酶抑制剂及其构效优化在阿尔茨海默病中的应用

阿尔茨海默病(Alzheimer’s disease,AD)是一种以进行性认知功能障碍和行为损害为特征的中枢神经系统退行性病变,而临床上缺乏有效治疗AD的药物。近些年来研究发现,多种酶抑制剂如胆碱酯酶抑制剂、单胺氧化酶抑制剂、分泌酶抑制剂等能改善胆碱能系统的障碍、Aβ的产生和沉积、Tau蛋白的过度磷酸化、氧化应激损伤、突触可塑性下降等AD发生发展的不同环节,从而改善AD症状和认知功能。本文综述了近年来酶抑制剂或抑制剂构效优化靶向调节胆碱酯酶、单胺氧化酶、分泌酶等在AD治疗中的研究进展,以期为AD的治疗和药物研发提供新思路。

治疗阿尔茨海默病创新药物研发进展

阿尔茨海默病(AD)是一种中枢神经系统退行性疾病,临床表现为进行性认知功能下降和行为损害,因其发病机制复杂,目前尚无有效的预防和治疗手段。近年来,依据AD发病机制和病理学特点进行靶向治疗逐渐成为新药开发的重点。靶向药物β淀粉样蛋白(Aβ)单克隆抗体阿度奴单抗和来卡内单抗获美国FDA批准用于AD的治疗,调节肠道菌群药物甘露特纳在中国批准上市,β分泌酶抑制剂、抗Aβ疫苗、tau蛋白聚集抑制剂等创新药物也表现出对AD的治疗潜力并先后进入临床试验。本文梳理近年来治疗AD的创新药物研究进展,分析创新药物研发策略,为治疗AD和开展相关新药研究提供参考和思路。

Effects of lipids on the activity and structural dynamics of gamma secretase: A study using coarse-grained molecular dynamics simulations

Gamma secretase(GS)is an intramembranous enzyme that acts on the amyloid precursor protein and Notch inside lipid membranes.The enzyme is responsible for amyloid-β propagation,one of the well-known causes of Alzheimer’s disease.However,the effects of lipids on GS activity and structural dynamics are unknown.Therefore,in this study,we performed coarse-grained molecular dynamics simulations to probe the effects of five individual lipids on GS.These lipids included 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine(POPE),1-palmitoyl2-oleoyl-sn-glycero-3-phosphocholine(POPC),1,2-dipalmitoyl-sn-phosphatidylcholine(DOPC),2-dimyristoyl-snglycero-3-phosphocholine(DMPC),and 1,2-dilauroyl-sn-glycero-3-phosphocholine(DLPC).These lipids are structurally characterized by different heads(i.e.,NH_(3)[PE]for POPE vs.NC_(3)[PC]for POPC),number of double bonds(one for POPC vs.two for DOPC),and alkyl tail chain lengths(16:1/18:1 for DOPC vs.14:0/14:0 for DMPC vs.12:0/12:0 for DLPC).This indicates distinct microenvironments and adjustable structural elements for catalytic function when GS is embedded.Our results revealed that the presence of more unsaturated bonds in DOPC than in POPC resulted in greater GS stability.Moreover,lipids with short alkyl tail chains or with PC heads instead of PE heads had improved mobility of the sixth transmembrane helix of GS,which is responsible for the considerable active site flexibility and presenilin 1 subunit plasticity.The length of the DMPC alkyl tail chain was between that of DOPC and DLPC because the up-down and cross-correlation motions of GS in DMPC was the lowest among the three lipids,and GS mobility in DMPC was the lowest among all five lipids.This may be because the alkyl tail chain length(i.e.,3.8 nm thickness of the DMPC bilayer)was suitable for GS embedding,thereby restraining more GS motions than that of the long(DOPC)or short lipids(DLPC).Collectively,these results indicated that GS activity can be modulated through changes in conformational fluctuations,structural perturbations,molecular motion,and cross-correlation motion when embedded in different lipids.Exploration of such fundamental information can reveal the possible mechanisms by which GS is affected by individual lipid species.

Effects of Honeysuckle Chlorogenic Acid on Secretory Enzymes,Lipoxygenase A4,and Biochemical Indicators inModel Mice with Aluminum Induced Alzheimer's Disease

[Objectives]To explore the effects of chlorogenic acid from honeysuckle on the secretion enzymes,lipoxygenase A4(LXA4),and blood biochemical indicators in mice with aluminum induced Alzheimer's disease(AD).[Methods]Chlorogenic acid was extracted from hon-eysuckle by ultrasound assisted alcohol extraction method.Seventy mice were randomly divided into normal group,model group,and low,me-dium and high dose groups of honeysuckle chlorogenic acid.All the mice in each group except for the normal group were given maltol aluminum by intraperitoneal injection to establish models of aluminum induced AD,continuously injected for 5 d and stopped for 2 d,totally poisoned for 8 weeks.Starting from the 5^(th) week of poisoning,the low,medium and high dose groups of honeysuckle chlorogenic acid were given honeysuck-le chlorogenc acid solution 40,80 and 160 mg/kg by gavage,respectively,while the normal group and the model group were fed with an equal volume of distilled water,all once daily,continuously gavaged until the end of the 8^(th) week.At the end of the experiment,the learning memory ability of the mice was tested by Y-type waler maze,and the number of tests required to reach the learning standard,the number of memory er-rors in 20 tests and the error rate of the mice were recorded.The brains of mice were taken to determine the contents of β-secretase,α-secre-tase,γ-secretase,LXA4 and acetylcholinesterase(AchE)in the homogenates of brain tissues by ELISA,and their blood was taken to deter-mine the biochemical indexes.[Results]Compared with the normal group,the number of learning tests,number of memory errors,error rate and the contents of β-secretase,γ-secretase and AchE in brain tissue of the mice in the model group were all significantly increased(all P<0.05),the contents of LXA4 in brain tissue were significantly decreased(all P<0.05),and the contents of α-secretase did not change significantly(all P>0.05);compared with the model group,the number of learning tests,the number of memory errors,the error rate and the content of β-secretase,γ-secretase and AchE in brain tissue were all significantly reduced(all P<0.05),the content of LXA4 in brain tissue of the high dose group of honeysuckle chlorogenic acid was significantly increased(P<0.05),and there was no significant change in the content of α-secretase in brain tissue of all groups of honeysuckle chlorogenic acid(all P>0.05).Compared with the normal group,the levels of blood glucose,TC,TG,ALT,BUN,Cr and UA in the model group and the levels of TC,TG and BUN in the low-and medium-dose groups of honeysuckle chlorogenic acid were significantly increased(all P<0.05),and the level of HDL-C in the model group and the levels of UA in the medium-and high-dose groups of honeysuckle chlorogenic acid were significantly decreased(all P<0.05);compared with the model group,the levels of blood glucose,ALT,BUN,UA in each group of honeysuckle chlorogenic acid,the levels of TC and Cr in medium and high dose groups of honeysuckle chlorogenic acid,and the level of TG in the high dose group of honeysuckle chlorogenic acid were all signifi-cantly lower(all P<0.05),while the level of HDL-C in the medium and high dose groups of honeysuckle chlorogenic acid and the level of to-tal protein in the high dose group of honeysuckle chlorogenic acid were all significantly higher(all P<0.05).[Conclusions]Chlorogenic acid from honeysuckle may improve AD induced by aluminum exposure via regulating related secretory enzymes,LXA4,and various biochemi-cal indicators.

基于BCMA突变体构建BCMA CAR-T细胞体外杀伤功能评价模型

目的:为解决野生型B细胞成熟抗原(BCMA)被γ分泌酶切割导致表达不稳定的问题,构建抵抗γ分泌酶切割的BCMA突变体并构建靶细胞,用于评价BCMA CAR-T细胞的杀伤功能。方法:将野生型BCMA的穿膜域替换为人CD8α穿膜域,构建抵抗γ分泌酶切割的BCMA突变体(BCMA-CD8αTM),构建过表达该突变体的U266(U266^(BCMA Mut))、K562(K562^(BCMA Mut))、SKOV3(SKOV3^(BCMA Mut))和CHO(CHO^(BCMA Mut))细胞;构建装载NFAT-EGFP报告基因的BCMA CAR Jurkat细胞(BCMA-CAR-Jurkat-Reporter)与U266^(BCMA Mut)细胞共培养,采用FCM检测该细胞中EGFP表达水平以指示NFAT激活水平,荧光素酶法检测BCMA CAR-T细胞对Luciferase标记的K562^(BCMA Mut)细胞的杀伤作用,实时无标记动态细胞分析技术(RTCA)检测BCMA CAR-T细胞对SKOV3^(BCMA Mut)和CHO^(BCMA Mut)细胞的杀伤作用。结果:应用γ分泌酶抑制剂LY411575抑制γ分泌酶活性,显著增强野生型U266细胞表面BCMA表达水平,平均荧光强度上调10倍以上;但撤除抑制剂后BCMA表达水平逐渐降低(P<0.01);BCMA-CD8αTM突变体可抵抗γ分泌酶的切割作用,在U266细胞表面稳定表达(P>0.05);U266细胞及过表达BCMA-CD8αTM的U266细胞与BCMA-CAR-Jurkat-Reporter细胞共培养后都可激活Reporter系统、增强EGFP表达,但该效应在BCMA-CD8αTM过表达的U266细胞中更显著(P<0.01);BCMA-CD8αTM在BCMA表达阴性的K562、SKOV3和CHO 3种靶细胞中成功过表达,且在LY411575处理下该突变体的表达水平仅有小幅度升高;荧光素酶法检测结果显示,不同效靶比下,BCMA CAR-T细胞均可特异、高效杀伤过表达BCMA-CD8αTM的K562细胞;RTCA结果显示,不同效靶比下,BCMA CAR-T细胞均可有效识别、杀伤过表达BCMACD8αTM的SKOV3和CHO细胞,但同等效靶比下的Mock-T细胞无此效应。结论:本实验构建的BCMA-CD8αTM突变体能够抵抗γ分泌酶的切割,在多种靶细胞表面稳定表达,为评价BCMA CAR-T细胞体外杀伤的有效性和特异性提供多种检测手段。

从炎症机制探讨Notch通路抑制剂对小鼠脑缺血模型的神经保护作用

目的探讨Notch通路抑制剂对小鼠脑缺血模型的神经保护作用。方法78只成年BALB/c小鼠按简单随机抽样方法分为Sham组、二甲基亚砜(DMSO)组、γ-分泌酶抑制剂(DAPT)组,每组26只;线栓法制作小鼠脑缺血模型,其中Sham组小鼠接受相同手术,但未插入缝线;DAPT组小鼠在大脑中动脉闭塞前3h腹腔注射DAPT溶液(5 mL·kg^(-1)),Sham组、二甲基亚砜(DMSO)组小鼠注射等剂量DMSO溶液,将Longa评分1~3分的小鼠作为实验小鼠;应用尼氏染色及TUNEL/NeuN免疫荧光双标染色鉴定右额叶皮质神经元,免疫荧光检测缺血半脑右半脑皮质Notch1、胶质纤维酸性蛋白(GFAP)阳性细胞,Westermblot检测缺血半脑右半脑皮质Hes1蛋白、Hes5蛋白表达,透射电镜观察各组右额叶皮质神经元超微结构变化,ELISA检测右前额叶皮质白细胞介素6(IL-6)、肿瘤坏死因子(TNF-α)水平。结果与Sham组比较,DMSO组、DAPT组皮质神经元存活数显著下降,皮质神经元凋亡数显著上升(P<0.05);与DMSO组比较,DAPT组皮质神经元存活数显著上升,皮质神经元凋亡数显著下降(P<0.05);与Sham组比较,DMSO组缺血半脑右半脑皮质Notch1、GFAP阳性细胞数显著上升(P<0.05),DAPT组缺血半脑右半脑皮质Notch1、GFAP阳性细胞数显著下降(P<0.05),DAPT组缺血半脑右半脑皮质Notch1、GFAP阳性细胞数显著低于DMSO组(P<0.05);与Sham组比较,DMSO组、DAPT组右半脑皮质Hes1蛋白、Hes5蛋白表达显著高于Sham组(P<0.05),DAPT组右半脑皮质Hes1蛋白、Hes5蛋白表达显著低于DMSO组(P<0.05);Sham组小鼠梗死周围皮质神经元超微结构正常,线粒体内外嵴结构正常;DMSO组小鼠神经元细胞核形状欠规则,核膜欠清晰,核周间隙扩大,染色质欠均匀呈聚集状,胞质内可见空泡,线粒体肿胀,线粒体内外嵴被破坏;DAPT组神经元超微及线粒体内外嵴结构接近正常;与Sham组比较,DMSO组、DAPT组右前额叶皮质IL-6、TNF-α因子水平显著上升(P<0.05),但DAPT组右前额叶皮质IL-6、TNF-α因子水平显著低于DMSO组(P<0.05)。结论Notch通路抑制剂的应用可阻断脑缺血后Notch信号通路传导,通过抑制Notch1及其下游Hes1蛋白、Hes5蛋白表达,下调IL-6、TNF-α水平来发挥神经元保护作用,值得临床重视。

阿尔茨海默病中蛋白质相互作用对β-分泌酶的调节机制

阿尔茨海默病(Alzheimer’s disease,AD)是一种慢性神经退行性疾病,目前尚无有效的治疗方案。AD发病机制十分复杂,学说众多,目前较为公认的仍然是淀粉样蛋白级联假说。该学说认为,淀粉样斑块在脑组织的沉积是AD发病的关键病理机制。β-分泌酶(β-site APP cleaving enzyme 1,BACE1)是淀粉样前体蛋白(amyloid precursor protein,APP)淀粉样降解途径中的限速酶,其降解产物β-淀粉样蛋白(β-amyloid protein,Aβ)是淀粉样斑块(amyloid plaques)的主要成分。AD患者大脑BACE1浓度和活性增加,是引起AD的重要因素。因此,探究BACE1生成及活性调节的影响因素不仅对于理解AD的发病机制至关重要,而且对于开发AD的新治疗靶点也有重要意义。蛋白质之间的相互作用在蛋白质参与的各种生物学过程中发挥着重要的作用,因而被广泛研究。BACE1的相互作用蛋白质可以通过直接结合、间接结合和参与各种细胞信号转导通路等方式直接或间接地在BACE1的转录、翻译、修饰与胞内运输等各个环节对BACE1进行调节,从而影响AD的发生与疾病的进程。本文将从BACE1的生物学功能,以及相互作用蛋白质对BACE1的转录、翻译、细胞内转运及其活性与降解的调节作用进行综述,探讨BACE1生理功能与活性的影响因素,以及BACE1互作蛋白质调控BACE1的作用机制,旨在为理解AD的发病机制以及药物研发提供新的思考。

Notch1信号通路通过调控Th17细胞参与实验性自身免疫性甲状腺炎的发生和发展

目的探讨Notch1信号通路是否通过调控辅助性T细胞17(Th17)参与实验性自身免疫性甲状腺炎(EAT)的发生和发展。方法将24只小鼠随机平均分为NC组、EAT-A组(给予猪甲状腺免疫球蛋白多点皮下注射)、EAT-B组(猪甲状腺免疫球蛋白多点皮下注射前给予γ分泌酶抑制剂腹腔注射)。HE染色观察甲状腺内淋巴细胞浸润程度;流式细胞术检测小鼠脾脏单核细胞(SMC)悬液中Th17细胞比例;ELISA法检测血清甲状腺球蛋白(TgAb)滴度和SMC培养上清白细胞介素-17A(IL-17A)浓度;实时PCR分析脾细胞中Notch1、Hes1、RORγt和IL-17A mRNA表达水平;Western blotting检测脾脏组织中IL-17A蛋白表达水平。结果EAT-A组和EAT-B组小鼠甲状腺中有不同程度淋巴细胞浸润,与NC组相比血清TgAb滴度显著升高(P<0.01)。EAT-A组和EAT-B组小鼠Notch1、Hes1、RORγt和IL-17A mRNA表达,以及SMC中Th17细胞比例、IL-17A浓度、IL-17A蛋白表达水平均高于NC组(均P<0.01)。EAT-B组上述指标显著低于EAT-A组(均P<0.01)。EAT-A组小鼠SMC中Th17细胞比例与血清TgAb滴度、脾脏Notch1 mRNA及IL-17A蛋白表达水平均呈正相关。结论EAT小鼠中Notch1信号通路的表达上调,阻断此信号通路后小鼠甲状腺炎症程度减轻,同时伴有Th17细胞比例明显降低,提示Notch1信号通路可能通过调控Th17细胞参与EAT的发生和发展。

基于明确靶标及分子对接验证技术探究五味子醇甲对阿尔茨海默病的作用机制

目的:明确五味子醇甲对阿尔茨海默病的作用机制。方法:选取24只大鼠按体质量随机分为空白组、模型组和给药组,每组8只。采用对大鼠海马CA1区注射Aβ1-40的方法制备阿尔茨海默病大鼠模型,造模1 d后灌胃给予30 mg/kg的五味子醇甲溶液,造模7 d后,进行Morris水迷宫行为学测试。在此基础上,对与阿尔茨海默病明确相关的β-分泌酶、雌激素受体β(ERβ)、谷氨酸受体1(NMDAR1)等蛋白进行验证,以蛋白表达量及药物成分与靶标作用的分子对接能进行评价,并通过分子对接技术计算五味子醇甲与各蛋白的对接能,达到理论验证的目的。结果:与空白组比较,模型组大鼠海马组织匀浆中β-分泌酶的活性含量明显增加(P<0.01),大鼠海马组织中ERβ表达显著降低(P<0.01),P-P38/P38表达明显升高(P<0.01),BACE1表达显著升高(P<0.01),NMDAR1表达明显降低(P<0.01);与模型组比较,给药组大鼠海马组织匀浆中β-分泌酶的活性含量明显减少(P<0.01),给药组大鼠海马组织中ERβ表达显著升高(P<0.01),P-P38/P38表达显著降低(P<0.01),BACE1表达显著降低(P<0.01),NMDAR1表达显著升高(P<0.01)。分子对接结果显示五味子醇甲与各靶蛋白对接的分子对接能稳定,从理论验证结果的可靠性。结论:基于已知靶点的五味子醇甲成分验证结果可知,五味子醇甲治疗阿尔茨海默病具有多成分、多靶点及多途径的作用特点,其作用机制可能与已知的阿尔茨海默病代谢通路直接相关,且通过对Beta-Secretase 1、ERβ、P-P38/P38、BACE1和NMDAR1蛋白的靶向调控实现。

P75NTR裂解抑制剂对CPZ诱导脱髓鞘小鼠认知功能及海马髓鞘的改善作用

目的探究P75神经营养素受体(neurotrophin receptor P75,P75NTR)裂解抑制剂对双环己酮草酰二腙(cuprizone,CPZ)诱导脱髓鞘小鼠认知功能及海马髓鞘的改善作用。方法采用连续喂食0.2%CPZ的方法构建急性脱髓鞘模型(CPZ小鼠),同时设立对照组;5周后,在CPZ小鼠海马区注射P75NTR裂解抑制剂或生理盐水。在第6周,通过水迷宫、高架十字迷宫实验检测小鼠行为学的改变;通过快蓝染色检测髓鞘脱失情况;通过Western blot检测海马组织中P75NTR及髓鞘碱性蛋白(myelin basic protein,MBP)的表达变化;通过免疫组织化学检测海马组织中MBP阳性表达量的变化。结果与对照组相比,CPZ小鼠逃避潜伏期增加,跨台次数、进入开臂及在开臂中活动时间减少(P均<0.05);快蓝染色结果显示,CPZ小鼠胼胝体区髓鞘结构疏松,着色明显变浅;CPZ小鼠海马区P75NTR表达增加(P<0.05);CPZ小鼠海马区MBP表达减少(P<0.05)。相比于生理盐水的干预,P75NTR裂解抑制剂干预后,小鼠逃避潜伏期降低,进入开臂及在开臂中活动时间增加(P均<0.05);P75NTR裂解抑制剂干预后,小鼠海马区MBP表达上升(P<0.05)。结论抑制P75NTR的裂解可以改善CPZ模型小鼠的认知功能障碍,其作用机制与减轻海马中髓鞘脱失有关。