Targeting amyloid precursor protein shuttling and processing-long before amyloid beta formation

Targeting early steps in amyloid-beta production：Alzheimer’s disease（AD）has a long history as the＂amyloid deposit＂disorder.Many disorders are now known to be caused by proteinβ-sheet misfolding and aggregation（e.g.,Parkinson’s disease：α-synuclein;Huntington’s disease：Huntingtin;

Effects of long-term estrogen replacement therapy on beta-amyloid precursor protein and mRNA expression in ovariectomized rat hippocampus

BACKGROUND： In vitro cultures of neural stem cells have shown that estrogen can regulate beta-amyloid precursor protein （β-APP） metabolism and reduce amyloid-beta production. OBJECTIVE： To investigate the effects of long-term oral administration of compound nylestriol or low-dose 17beta-estradiol on β-APP and mRNA expression in the hippocampus of ovariectomized （OVX） rats. DESIGN, TIME AND SETTING： This randomized and controlled experiment was performed at the Animal Laboratory and Laboratory of Endocrine and Metabolic Disease, Xiangya Second Hospital of Central South University between April 2003 and May 2004. MATERIALS： According to body mass, 50 six-month-old female Sprague-Dawley rats were randomly divided into five groups （n = 10 per group）： normal control, sham operation, OVX model, 17beta-estradiol （Sigma, USA）, and compound nylestriol tablet （Laboratory of Endocrine and Metabolic Disease, Xiangya Second Hospital of Central South University） groups. METHODS： Rats in OVX plus 17beta-estradiol and OVX plus compound nylestriol tablet groups underwent ovariectomy. On the second day after surgery, rats were intragastrically given 17beta-estradiol （100 μg/kg）, once per day or compound nylestriol tablet （0.5 mg/kg） and levonorgestrel （0.15 mg/kg） every 2 days. MAIN OUTCOME MEASURES： β-APP expression in the hippocampus of OVX rats was determined using immunohistochemistry （SABC method） and β-APP mRNA expression was analyzed by in situ hybridization. The results were quantitatively analyzed using cell counting and average optical density. RESULTS： The number and optical density of β-APP-positive neurons in every subregion of the hippocampus of OVX rats was dramatically increased compared with normal and sham operation groups following 35 weeks of administration （P 〈 0.05）. Levels of β-APP were decreased following oral administration of compound nylestriol or 17beta-estradiol. In situ hybridization showed that long-term estrogen deficiency and oral administration of compound nylestriol or 17beta-estradiol did not alter the number of β-APP mRNA-positive neurons. CONCLUSION： The results show that long-term estrogen deficiency results in an increase of expression of β-APP though no changes in the expression of β-APP mRNA are detected. Replacement of estrogen with low-dose 17 beta-estradiol or compound nylestriol tablet inhibits the expression of β-APP in the hippocampus to the same extent.

Observation of amyloid precursor protein cleavage and Aβ generation in living cells by using multiphoton laser scanning microscopy

Objective To investigate the proteolytic mechanism of amyloid precursor protein （APP） and to explore amyloidbeta （Aβ） generation in living neurons. Methods DNA fragments were amplified by PCR or synthesized. The four fragments, CFP, 54bp, YFP and C99 were ligated into pcDNA3.0 vector to construct the recombinant plasmids pcDNA3.0-CFP-54bp- YFP and pcDNA3.0-CFP-54bp-YFP-C99. The SH-SY5Y cells were transiently transfected with pcDNA3.0-CFP-54bp-YFP or pcDNA3.0-CFP-54bp-YFP-C99. The expression of fusion gene was examined under a multiphoton laser scanning microscope. Fluorescence resonance energy transfer （FRET） was used to measure the β cleavage and γ cleavage of APE Aβ generation was confirmed by immunocytochemistry and multiphoton laser scanning microscopy. Cell viability was tested by MTT assay at different time points. Results （1） The double restriction endonuclease digestion and sequencing analysis confirmed the authenticity of the recombinant plasmids pcDNA3.0-CFP-54bp-YFP and pcDNA3.0-CFP-54bp- YFP-C99. （2） Blue and yellow fluorescences were detected in the transfected cells. （3） FRET occurred in pcDNA3.0-CFP- 54bp-YFP-transfected cells but not in pcDNA3.0-CFP-54bp-YFP-C99-transfected cells. （4） Aβ was produced in the pcDNA3.0- CFP-54bp-YFP-C99 transfected cells. （5） Aβ-deposition was widespread in the cell. （6） Cell viability decreased along with the intracellular Aβ deposition. Conclusion C99 is important for the APP β cleavage. Aβ may be generated and deposited in cells at the early stage of Alzheimer＇s disease. Intracellular Aβ accumulation brings deleterious effects on cells.

Physiological effects of amyloid precursor protein and its derivatives on neural stem cell biology and signaling pathways involved

The pathological implication of amyloid precursor protein(APP)in Alzheimer’s disease has been widely documented due to its involvement in the generation of amyloid-β peptide.However,the physiological functions of APP are still poorly understood.APP is considered a multimodal protein due to its role in a wide variety of processes,both in the embryo and in the adult brain.Specifically,APP seems to play a key role in the proliferation,differentiation and maturation of neural stem cells.In addition,APP can be processed through two canonical processing pathways,generating different functionally active fragments:soluble APP-α,soluble APP-β,amyloid-β peptide and the APP intracellular C-terminal domain.These fragments also appear to modulate various functions in neural stem cells,including the processes of proliferation,neurogenesis,gliogenesis or cell death.However,the molecular mechanisms involved in these effects are still unclear.In this review,we summarize the physiological functions of APP and its main proteolytic derivatives in neural stem cells,as well as the possible signaling pathways that could be implicated in these effects.The knowledge of these functions and signaling pathways involved in the onset or during the development of Alzheimer’s disease is essential to advance the understanding of the pathogenesis of Alzheimer’s disease,and in the search for potential therapeutic targets.

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.

Lipid rafts participate in aberrant degradative autophagic-lysosomal pathway of amyloid-beta peptide in Alzheimer's disease

Amyloid-beta peptide is the main component of amyloid plaques, which are found in Alzhei- mer＇s disease. The generation and deposition of amyloid-beta is one of the crucial factors for the onset and progression of Alzheimer＇s disease. Lipid rafts are glycolipid-rich liquid domains of the plasma membrane, where certain types of protein tend to aggregate and intercalate. Lipid rafts are involved in the generation of amyloid-beta oligomers and the formation of amyloid-beta peptides. In this paper, we review the mechanism by which lipid rafts disturb the aberrant deg- radative autophagic-lysosomal pathway of amyloid-beta, which plays an important role in the pathological process of Alzheimer＇s disease. Moreover, we describe this mechanism from the view of the Two-system Theory of fasciology and thus, suggest that lipid rafts may be a new target of Alzheimer＇s disease treatment.

基于GEO数据库构建APP、APBA和APBB家族的胃癌预后评估模型

目的基于淀粉样β前体蛋白(amyloid beta precursor protein,APP)家族、淀粉样β前体蛋白结合蛋白A(amyloid beta precursor protein binding family A,APBA)家族和淀粉样β前体蛋白结合蛋白B(amyloid beta precursor protein binding family B,APBB)家族构建胃癌预后评估模型。方法从基因表达综合(gene expression omnibus,GEO)数据库下载GSE62254胃癌数据集作为训练集,GSE15459作为验证集。利用Cox回归分析筛选APP家族、APBA家族和APBB家族中胃癌预后的独立危险因素;分别建立基于三家族独立预后因素的风险评分1(risk score 1,RS1)、RS1联合病理学参数的RS2、传统TNM分期的RS3;卡方检验分析RS1与胃癌患者临床病理特征的关系;利用单细胞在线分析网站,分析纳入RS1模型的基因在不同细胞亚群中的表达情况;利用CIBERSORT分析RS1对不同免疫细胞浸润的影响;利用基因集富集分析(gene set enrichment analysis,GSEA)进行通路富集分析。结果APLP2、APBB1、APBB2是胃癌患者预后的独立危险因素(P<0.05),基于三者的风险评分RS1高组患者生存期明显短于RS1低组患者。联合临床病理学参数的Cox回归分析显示,N分期、M分期、Lauren分型和RS1是胃癌患者预后的独立危险因素(P<0.05)。基于此构建的RS2(AUC=0.767)比仅基于T分期、N分期、M分期构建的RS3(AUC=0.719)预测准确率提高了4.8%。RS1和肿瘤T分期呈正相关(P<0.05),RS1高组CD4静息细胞浸润较高,激活细胞浸润较低,M2巨噬细胞浸润较高。GSEA通路分析显示,高RS1组患者富集于MAPK、MTOR和WNT等通路。结论本研究成功构建了基于APP、APBA和APBB家族的胃癌预后评估模型,该模型能够较准确地判断胃癌患者预后。

Transthyretin—A Key Gene Involved in Regulating Learning and Memory in Brain, and Providing Neuroprotection in Alzheimer Disease via Neuronal Synthesis of Transthyretin Protein

Transthyretin (TTR), a carrier protein present in the liver and choroid plexus of the brain, has been shown to be responsible for binding thyroid hormone thyroxin (T4) and retinol in plasma and cerebrospinal fluid (CSF). TTR aids in sequestering of beta-amyloid peptides Aβ deposition, and protects the brain from trauma, ischemic stroke and Alzheimer disease (AD). Accordingly, hippocampal gene expression of TTR plays a significant role in learning and memory as well as in simulation of spatial memory tasks. TTR via interacting with transcription factor CREB regulates this process and decreased expression leads to memory deficits. By different signaling pathways, like MAPK, AKT, and ERK via Src, TTR provides tropical support through megalin receptor by promoting neurite outgrowth and protecting the neurons from traumatic brain injury. TTR is also responsible for the transient rise in intracellular Ca2+ via NMDA receptor, playing a dominant role under excitotoxic conditions. In this review, we tried to shed light on how TTR is involved in maintaining normal cognitive processes, its role in learning and memory, under memory deficit conditions;by which mechanisms it promotes neurite outgrowth;and how it protects the brain from Alzheimer disease (AD).

微RNA-196a-1-3p靶向Ras响应元件结合蛋白调控胆管癌细胞增殖的机制研究

目的探讨转化生长因子β(TGF-β)调控人胆管癌细胞系RBE细胞增殖的关键微RNA(miRNA)及其潜在的机制。方法该研究起止时间为2020年1月至2022年1月。磷酸盐缓冲液(PBS)处理为对照组,TGF-β处理为TGF-β组,TGF-β抗体处理为抗体组。检测三组RBE细胞的增殖水平。miRNA高通量测序检测三组RBE细胞的miRNA调控变化,并进行miRNA模拟物过表达筛选鉴定受TGF-β调控的影响RBE细胞增殖水平的关键miRNA。miRNA数据库(miRDB)在线分析miRNA的潜在底物,并通过小干扰RNA(siRNA)敲低筛选鉴定影响RBE细胞增殖水平的关键底物。结果相比于对照组,TGF-β组RBE细胞的增殖水平上升(1.62±0.07比2.35±0.09,P<0.05),抗体组RBE细胞的增殖水平下降(1.62±0.07比1.11±0.08,P<0.05)。过表达微RNA-196a-1-3p(miR-196a-1-3p)时,RBE细胞的增殖水平下降(P<0.05)。敲低Ras响应元件结合蛋白(RREB1)时,RBE细胞的增殖水平下降(P<0.05)。过表达miR-196a-1-3p后,RBE细胞中RREB1的信使RNA(mRNA)和蛋白水平下降(P<0.05)。敲低miR-196a-1-3p后,RBE细胞中RREB1与SMAD家族蛋白3(SMAD3)的相互作用增加。敲低SMAD3后,RBE细胞的增殖水平下降(P<0.05)。与仅敲低SMAD3相比,敲低SMAD3的同时过表达RREB1的RBE细胞的增殖水平无显著变化,并且同时敲低SMAD3和miR-196a-1-3p的RBE细胞的增殖水平无显著变化。结论TGF-β能够通过miR-196a-1-3p/RREB1/SMAD3轴促进RBE细胞增殖;miR-196a-1-3p和RREB1可作为潜在的治疗胆管癌的靶标,为针对该靶标的新药研发奠定了基础。

Targeting prion-like protein spreading in neurodegenerative diseases

The infectious template-mediated protein conversion is a unique mechanism for the onset of rare and fatal neurodegenerative disorders known as transmissible spongiform encephalopathies, or prion diseases, which affect humans and other animal species. However, emerging studies are now demonstrating prion-like mechanisms of self-propagation of protein misfolding in a number of common, non-infectious neurodegenerative diseases such as Alzheimer＇s disease and Parkinson＇s disease. It has been proposed that distinct and unrelated proteins（beta-amyloid, tau, α-synuclein, TAR DNA-binding protein 43 and huntingtin, etc.） associated with common neurodegenerative disorders can seed conversion and spread via cellto-cell transfer, sustaining the transmission of neurotoxic agents along a stereotypic route, sharing features at the heart of the intrinsic nature of prions. Here we review the most recent development on both the molecular mechanisms underlying the pathogenesis of prion-like neurodegenerative diseases as well as innovative methods and strategies for potential therapeutic applications.

circBIRC6 contributes to the development of non-small cell lung cancer via regulating microRNA-217/amyloid beta precursor protein binding protein 2 axis

Background:Circular RNAs(circRNAs)are considered to be important regulators in cancer biology.In this study,we focused on the effect of circRNA baculoviral inhibitor of apoptosis protein(IAP)repeat containing 6(circBIRC6)on non-small cell lung cancer(NSCLC)progression.Methods:The NSCLC and adjacent non-tumor tissues were collected at Shanghai Ninth People's Hospital.Quantitative real-time polymerase chain reaction was conducted for assessing the levels of circBIRC6,amyloid beta precursor protein binding protein 2(APPBP2)messenger RNA(mRNA),baculoviral IAP repeat containing 6 mRNA(BIRC6),and microRNA-217(miR-217).Western blot assay was adopted for measuring the protein levels of APPBP2,E-cadherin,N-cadherin,and vimentin.Colony formation assay,transwell assay,and flow cytometry analysis were utilized for evaluating cell colony formation,metastasis,and apoptosis.Dualluciferase reporter assay and RNA immunoprecipitation assay were carried out to determine the interaction between miR-217 and circBIRC6 and APPBP2 in NSCLC tissues.The murine xenograft model assay was used to investigate the function of circBIRC6 in tumor formation in vivo.Differences were analyzed via Student's t test or one-way analysis of variance.Pearson's correlation coefficient analysis was used to analyze linear correlation.Results:CircBIRC6 was overexpressed in NSCLC tissues and cells.Knockdown of circBIRC6 repressed the colony formation and metastasis and facilitated apoptosis of NSCLC cells in vitro and restrained tumorigenesis in vivo.Mechanically,circBIRC6 functioned as miR-217 sponge to promote APPBP2 expression in NSCLC cells.MiR-217 inhibition rescued circBIRC6 knockdown-mediated effects on NSCLC cell colony formation,metastasis,and apoptosis.Overexpression of miR-217 inhibited the malignant phenotypes of NSCLC cells,while the effects were abrogated by elevating APPBP2.Conclusion:CircBIRC6 aggravated NSCLC cell progression by elevating APPBP2 via sponging miR-217,which might provide a fresh perspective on NSCLC therapy.

Blocking beta 2-adrenergic receptor inhibits dendrite ramification in a mouse model of Alzheimer's disease

Dendrite ramification affects synaptic strength and plays a crucial role in memory. Previous studies revealed a correlation between beta 2-adrenergic receptor dysfunction and Alzheimer＇s disease （AD）, although the mechanism involved is still poorly understood. The current study investigated the potential effect of the selective β2-adrenergic receptor antagonist, ICI 118551 （ICI）, on Aβ deposits and AD-related cognitive impairment. Morris water maze test results demonstrated that the performance of AD-transgenic （TG） mice treated with ICI （AD-TG/ICI） was significantly poorer compared with NaCl-treated AD-TG mice （AD-TG/NaCl）, suggesting that β2-adrenergic receptor blockage by ICI might reduce the learning and memory abilities of mice. Golgi staining and immunohistochemical staining revealed that blockage of the β2-adrenergic receptor by ICI treatment decreased the number of dendritic branches, and ICI treatment in AD-TG mice decreased the expression of hippocampal synaptophysin and synapsin 1. Western blot assay results showed that the blockage of β2-adrener- gic receptor increased amyloid-β accumulation by downregulating hippocampal a-secretase activity and increasing the phosphorylation of amyloid precursor protein. These findings suggest that blocking the β2-adrenergic receptor inhibits dendrite ramification of hippocampal neurons in a mouse model of AD.

T cells promote the regeneration of neural precursor cells in the hippocampus of Alzheimer's disease mice

Alzheimer＇s disease is closely associated with disorders of neurogenesis in the brain, and growing evidence supports the involvement of immunological mechanisms in the development of the disease. However, at present, the role of T cells in neuronal regeneration in the brain is unknown. We injected amyloid-beta 1-42 peptide into the hippocampus of six BALB/c wild-type mice and six BALB/c-nude mice with T-cell immunodeficiency to establish an animal model of Alzhei- mer＇s disease. A further six mice of each genotype were injected with same volume of normal saline. Immunohistochemistry revealed that the number of regenerated neural progenitor cells in the hippocampus of BALB/c wild-type mice was significantly higher than that in BALB/c-nude mice. Quantitative fluorescence PCR assay showed that the expression levels of peripheral T cell-associated cytokines （interleukin-2, interferon-y） and hippocampal microglia-related cyto- kines （interleukin-113, tumor necrosis factor-a） correlated with the number of regenerated neural progenitor cells in the hippocampus. These results indicate that T cells promote hippocampal neurogenesis in Alzheimer＇s disease and T-cell immunodeficiency restricts neuronal regeneration in the hippocampus. The mechanism underlying the promotion of neuronal regeneration by T cells is mediated by an increased expression of peripheral T cells and central microglial cytokines in Alzheimer＇s disease mice. Our findings provide an experimental basis for understanding the role of T cells in Alzheimer＇s disease.

Beta secretase activity in peripheral nerve regeneration

While the peripheral nervous system has the capacity to regenerate following a nerve injury,it is often at a slow rate and results in unsatisfactory recovery,leaving patients with reduced function.Many regeneration associated genes have been identified over the years,which may shed some insight into how we can manipulate this intrinsic regenerative ability to enhance repair following peripheral nerve injuries.Our lab has identified the membrane bound protease beta-site amyloid precursor protein-cleaving enzyme 1（BACE1）,or beta secretase,as a potential negative regulator of peripheral nerve regeneration.When beta secretase activity levels are abolished via a null mutation in mice,peripheral regeneration is enhanced following a sciatic nerve crush injury.Conversely,when activity levels are greatly increased by overexpressing beta secretase in mice,nerve regeneration and functional recovery are impaired after a sciatic nerve crush injury.In addition to our work,many substrates of beta secretase have been found to be involved in regulating neurite outgrowth and some have even been identified as regeneration associated genes.In this review,we set out to discuss BACE1 and its substrates with respect to axonal regeneration and speculate on the possibility of utilizing BACE1 inhibitors to enhance regeneration following acute nerve injury and potential uses in peripheral neuropathies.

Inhibiting 5-hydroxytryptamine receptor 3 alleviates pathological changes of a mouse model of Alzheimer's disease

Extracellular amyloid beta(Aβ) plaques are main pathological feature of Alzheimer’s disease.However,the specific type of neuro ns that produce Aβ peptides in the initial stage of Alzheimer’s disease are unknown.In this study,we found that 5-hydroxytryptamin receptor 3A subunit(HTR3A) was highly expressed in the brain tissue of transgenic amyloid precursor protein and presenilin-1 mice(an Alzheimer’s disease model) and patients with Alzheimer’s disease.To investigate whether HTR3A-positive interneurons are associated with the production of Aβ plaques,we performed double immunostaining and found that HTR3A-positive interneurons were clustered around Aβ plaques in the mouse model.Some amyloid precursor protein-positive or β-site amyloid precursor protein cleaving enzyme-1-positive neurites near Aβ plaques were co-localized with HTR3A interneurons.These results suggest that HTR3A-positive interneurons may partially contribute to the generation of Aβ peptides.We treated 5.0-5.5-month-old model mice with tro pisetron,a HTR3 antagonist,for 8 consecutive weeks.We found that the cognitive deficit of mice was partially reversed,Aβ plaques and neuroinflammation we re remarkably reduced,the expression of HTR3 was remarkably decreased and the calcineurin/nuclear factor of activated T-cell 4 signaling pathway was inhibited in treated model mice.These findings suggest that HTR3A interneurons partly contribute to generation of Aβ peptide at the initial stage of Alzheimer’s disease and inhibiting HTR3 partly reve rses the pathological changes of Alzheimer’s disease.

氟西汀对Aβ_(25-35)诱导小胶质细胞NLRP3炎性小体活化及细胞焦亡的影响

目的探讨氟西汀对β-淀粉样蛋白25-35(Aβ_(25-35))诱导的BV2小胶质细胞炎性反应的作用及机制。方法应用Aβ_(25-35)刺激BV2细胞模拟阿尔茨海默病(AD)的炎性环境。实验分为空白对照组、Aβ_(25-35)组、Aβ_(25-35)+不同浓度氟西汀组和Aβ_(25-35)+双硫仑组。采用CCK8法检测细胞活力,通过乳酸脱氢酶(LDH)实验、Annexin V-FITC/PI双染色及透射电子显微镜评估细胞焦亡水平。采用Western blot法检测核苷酸结合寡聚化结构域样受体蛋白3(NLRP3)、凋亡相关斑点样蛋白(ASC)、半胱氨酸蛋白酶-1(caspase-1)、活化半胱氨酸蛋白酶-1(cleaved-caspase-1)、膜穿孔蛋白D(GSDMD)等炎性小体及焦亡相关蛋白的表达,酶联免疫吸附试验(ELISA)法测定促炎因子白细胞介素1β(IL-1β)和白细胞介素18(IL-18)的表达,DCFH-DA荧光染色法检测活性氧(ROS)的水平。结果与空白对照组相比,Aβ_(25-35)组的细胞活力降低,NLRP3炎性小体和焦亡相关因子(NLRP3、ASC、caspase-1、cleaved-caspase-1、GSDMD、IL-1β、IL-18)的表达明显增加,LDH释放量及细胞焦亡比例升高,细胞内ROS的生成增多,差异均有显著性(F=2.787~30.457,P<0.05);与Aβ_(25-35)组相比,经不同浓度氟西汀预处理的细胞存活率明显增高,促炎因子IL-1β、IL-18表达明显减少,炎性小体及焦亡相关蛋白的表达下调,LDH的释放量和细胞焦亡比例降低,ROS的生成明显减少,其中以高剂量(20μmol/L)氟西汀的作用最为显著。结论氟西汀可抑制Aβ_(25-35)诱导的BV2细胞ROS生成、NLRP3炎性小体活化和细胞焦亡,这为延缓AD进展提供了新的治疗思路。

Spectroscopic and calorimetric studies of congo red dye-amyloid peptide complexes

Thermodynamic properties of complexes of Con ?go Red (CR) dye with amyloid ? (A?) peptides were studied by both absorption spectroscopy and isothermal titration calorimetry (ITC). Based on the absorption spectrum for the formation of CRAβ complexes in phosphate buffered saline solution (pH 7.4), van’t Hoff plots over a temperature range of 10oC to 70oC were created for CRAβ140, Aβ1228, and Aβ142. The plot for CR Aβ1228 complex showed a relatively linear feature within the given temperature range with ?H = –10.1 ?0.6 kJ/mol and ?S = + 0.128 ? 0.002 kJ/(mol K). However, the plot for CRAβ140 and CRAβ142 complexes exhibited two distinct linear regions with opposite slopes centered at a specific temperature, Ts, which was 54.7 ? 0.2℃ and 34.8 ? 0.2℃, respectively. The ITC experiments conducted at 25℃in water exhibited quite a different situation from the above mentioned spectroscopic approach. The ITC studies yielded a ?H of –85.3 ? 0.2 kJ/mol for the CRAβ1228 complex with negative entropy change –0.152 kJ/mol K). For CRAβ140, the ITC studies indicated the presence of two binding sites with ?H1 = –81.8 ? 0.3 kJ/mol and ?H2 = –119.5 ? 0.2 kJ/mol with K1 = 5.5 ? 0.7 ? 106 M1 and K2 = 6.9 ? 2.4 ? 108 M1, respectively. These binding constants are consistent with the model suggested by several studies. Both binding sites showed negative entropy changes suggesting that the formation of the complex is enthalpically driven. The disagreement in thermochemical values between two different methods confirmed that the enthalpy and entropy are heavily dependent on temperature and buffer/salt environment, and may involve inherently different reaction paths.

Effect of Tiantai No.1 (天泰1号) on β-Amyloid-induced Neurotoxicity and NF-κ B and cAMP Responsive Element-binding Protein

Objective： To investigate the effect and molecular mechanism of Tiantai No.1 （天泰1号）, a compound Chinese herbal preparation, for the prevention and reduction of neurotoxicity induced by betaamyloid peptides （Abeta） in vitro and its effects on nuclear factor-κB （NF-κB） and cAMP responsive element-binding protein （CREB） pathways using the gene transfection technique. Methods： B104 neuronal cells were used to examine the effects of Tiantai No.1 on lowering the neurotoxicity induced by Abeta. The cells were pre-treated with Tiantai No.1 at doses of 50, 100,150, or 200μg/mL respectively for 3 days and co-treated with Tiantai No.1 and beta-amyloid peptidel-40 （Aβ 1-40, 10 μmol/L） for 48 h or post-treated with Tiantai No.1 for 48 h after the cells were exposed to beta-amyloid peptides25-35 （Aβ 25-35） for 8 h. In gene transfection assays, cells were treated with Tiantai No.1 at 50 μg/mL and 150μg/mL for 5 days or co-treated with Tiantai No.1 and A 13 1-40 （5 μmo/L） for 3 days after electroporation for the evaluation of NF- κB and CREB expression. Results： Pre-treating and co-treating B104 neuronal cells with Tiantai No.1 lowered the neurotoxicity induced by Abeta, and post-treating with Tiantai No.1 reduced or blocked B104 neuronal apoptotic death induced by Abeta （P〈0.05, P〈0.01）. With a dose-dependent relationship, the same treatments increased the expression of NF-κB or CREB in B104 neuronal cells （P〈0.05, P〈0.01）. Meanwhile, Tiantai No.1 reduced Aβ-40 induced inhibition on NF-κB expression （P〈0.01）. Conclusions： Tiantai No.1 can protect neurons against the neurotoxicity induced by Abeta. The neuroprotective mechanisms may be associated with the activation of NF-κB and cAMP cellular signal pathways.

Aβ_(1-42)诱导阿尔茨海默病模型大鼠海马内细胞因子表达变化的研究

目的探讨β淀粉样蛋白(Aβ)1-42诱导的阿尔茨海默病(AD)模型大鼠海马内致炎细胞因子和抗炎细胞因子表达的变化。方法 24只SD大鼠随机分为正常对照组(intact组)、PBS对照组和AD模型组。PBS对照组为海马CA1区注射PBS,AD模型组为海马CA1区注射Aβ1-42。应用Morris水迷宫测试大鼠逃避潜伏期;Nissl染色观察海马CA1区神经元的损害情况;Western blot方法检测海马组织中淀粉样前体蛋白(APP)以及蛋白质磷酸酶-2A(PP2A)的表达量;Real-time PCR法检测海马内细胞因子白介素(IL)-1β、肿瘤坏死因子(TNF)-α、干扰素(IFN)-γ、IL-4、IL-10和转化生长因子(TGF)-β的mRNA水平。结果大鼠双侧海马内注射Aβ1-42后,动物的空间学习记忆能力降低、海马CA1区神经元胞体丢失、海马内APP表达上调而PP2A表达下调。AD模型大鼠的海马内,致炎细胞因子IL-1β、TNF-α和IFN-γ的mRNA表达上调,而抗炎细胞因子IL-4、IL-10和TGF-β的mRNA表达下调。结论 AD大鼠脑内存在致炎/抗炎失衡的神经炎症,它参与了AD的发病机制。

大鼠弥漫性轴突损伤早期淀粉样前体蛋白(β-APP)表达的实验研究

目的观察大鼠弥漫性轴突损伤(DAI)早期脑内各部位淀粉样前体蛋白(β-APP)表达的变化。方法应用瞬间旋转致伤装置使16只SD大鼠发生DAI,并于伤后3h、6h分批处死(每时间点8只),另取8只大鼠作为正常对照,在24h后处死。取各组大鼠脑标本进行免疫组织化学观察,检查损伤后早期不同时间皮质下白质、海马、胼胝体、脑干区域的病理学改变。各部位(胼胝体、海马、脑干)的切片在显微镜下(200倍)进行半定量分析。结果损伤后3h,大脑皮质下白质、胼胝体和脑干β-APP呈弱阳性表达;损伤后6h,轴突局部免疫反应阳性较前明显增强,范围增大,半定量分析显示,胼胝体、海马、脑干的免疫反应均强于3h组。结论β-APP在DAI早期(伤后3h)即有明确表达,并呈逐渐增强趋势,可作为DAI早期的标志物。