tau蛋白和磷酸化tau蛋白对神经系统疾病的影响

tau蛋白是一种神经元微管相关蛋白,参与轴突微管组装的调节。其磷酸化水平的增高与多种神经退行性疾病息息相关,如阿尔茨海默病、帕金森病、额颞叶痴呆、亨廷顿病,等。有研究表明其与脑血管病的发生发展密不可分。而昼夜节律作为维持机体日常生命活动以及体内稳态的重要调节器,受昼夜节律因子的调节,其紊乱可诱发神经退行性疾病相关致病蛋白的积累和相关致病激素的异常分泌,从而加剧疾病的进展。文中主要围绕磷酸化tau蛋白和昼夜节律对神经系统疾病的影响进行论述。     

基于类淋巴系统机制治疗阿尔茨海默病的研究进展

阿尔茨海默病(Alzheimer disease, AD)是一种起病隐匿,呈进行性发展的神经系统退行性疾病。近些年,越来越多的研究发现类淋巴系统与AD中的异常蛋白清除障碍密切相关。本文总体阐述了类淋巴系统的发现及其与AD的关系,重点对其对脑内β-淀粉样蛋白(amyloid-beta protein, Aβ)、tau蛋白的清除功能及影响因素,以及基于类淋巴系统机制治疗AD的最新研究成果进行综述。     

PrP可抑制tau介导的体外微管形成作用

目的研究朊蛋白（PrP）对微管相关蛋白（tau）介导的体外微管形成的影响。方法我们从兔脑组织中纯化出微管蛋白，并纯化出原核表达的tau和PrP蛋白。利用电子显微镜技术显示微管蛋白的聚集、tau对微管蛋白的聚集的影响，及PrP对tau介导的微管蛋白形成微管的影响。通过GST pull down实验研究tau与微管蛋白的相互作用，PrP对tau与微管蛋白相互作用的影响。结果电子显微镜负染显示纯化的微管蛋白在一定的实验条件下可聚集形成直径为25Nm的微管结构。在反应体系中加入tau后微管样结构的形成明显增加，而加入PrP后可显著地抑制tau对微管结构形成的促进作用。重组tau能与提取的天然微管蛋白在体外结合，而PrP可明显地抑制tau与微管蛋白的结合作用，并呈现剂量依赖关系。结论tau蛋白可促进微管蛋白形成微管结构，而PrP可通过与tau的相互作用抑制微管的形成。     

tau蛋白和中枢神经系统变性疾病

tau蛋白是脑内神经元细胞支架蛋白之一。其正常功能是促进微管蛋白组成微管 ,并维持已形成微管的稳定性。参与维持细胞形态、信息传递、细胞分裂等重要生物学过程 ,是轴突生长发育和神经元极性形成的不可缺少因素。近年来发现tau蛋白与一些中枢神经系统变性疾病密切相关。我们将综述此方面的研究进展。一、tau蛋白的生物学结构tau蛋白是一种神经元微管相关蛋白 ,由微管相关蛋白和管蛋白组成的微管是细胞骨架的重要组成成分 ,与细胞有丝分裂、细胞内物质转运等多种功能有关。正常情况下广泛存在于神经元内 ,在脑内主要集中在神经细胞轴突之中…     

ELISA测定Alzheimer病患者脑脊液中tau蛋白的含量

随人口老龄化 ,“老年痴呆”已成为世界性健康热点之一 ,我国已把它列为国家级重点的九五攻关课题之一。tau蛋白成为老年性痴呆研究中热门话题的主要理由 :( 1)tau蛋白又称微管相关蛋白 (microtubuleassociatedprotein ,MAP)tau ,具有合成和稳定神经元细胞骨骼的作用。tau蛋白正常分布于神经轴索中 ,且具有许多磷酸化位点 ,若tau蛋白异常磷酸化 ,则极易形成双螺旋纤维丝 (pairedhelicalfilament,PHF) ,进而组成神经原纤维缠结 (neurofilamenttangle ,NFT) ,于是致老年性痴呆。 ( 2 )作为群体来说 ,脑脊液中tau蛋白水平 ,老年性痴呆病人组明显高于年龄相匹配的非痴呆老人组 (以下简称对照组 )。有些作者试图用脑脊液中tau蛋白水平作为老年性痴呆早期诊断的指标 ,但其前景暗淡 ,主要理由 :( 1)脑脊液中tau蛋白水平的分布范围 ,老年性痴呆组和对照组间有相当重叠 ;不能用其水平高低来判定是否患老年性痴呆 ,即不能用于鉴别是患老年性痴呆患者和正常老龄化老人。 ( 2 )脑脊液中tau蛋白水平增高 ,不仅可见于老年性痴呆患者 ,也可见于其他神经系统疾病患者 ,如血管性痴呆、Lewy体痴呆、颞叶痴呆、帕金森病 ,Creutzfeldt Jakob病、肌萎缩侧索硬化、脑血管病、多发性硬化、Guillain Barr啨综合征?床荒苡盟从肽     

慢性酒精中毒患者血清中tau蛋白、Aβ1-42的测定及临床意义

目的研究酒精中毒患者血清tau蛋白及Aβ1-42测定的临床意义及其参与酒精致神经系统损害的机制。方法 40名慢性酒精中毒患者(饮酒时间均超过5年)按饮酒年限分为饮酒20年以上组及20年以下组。按头部CT结果分为脑萎缩组及无脑萎缩组。用ELISA方法测定40名酒精中毒患者及16名健康人的血清tau蛋白及Aβ1-42水平。结果 (1)慢性酒精中毒患者血清tau蛋白高于正常对照组,但两者之间无统计学意义。脑萎缩组血清tau蛋白水平显著高于无脑萎缩组及正常对照组,差异具有统计学意义(P<0.05)。饮酒20年以上组血清tau蛋白显著高于饮酒20年以下组以及正常对照组,差异有统计学意义(P<0.05)。(2)慢性酒精中毒患者血清Aβ1-42明显高于正常对照组,有统计学意义(P<0.01)。脑萎缩组及无脑萎缩组血清Aβ1-42均明显高于正常对照组,且有统计学意义(P<0.01)。饮酒20年以上组及饮酒20年以下组血清Aβ1-42均明显高于正常对照组,且有统计学意义(P<0.01)。结论 (1)慢性酒精中毒患者血清tau蛋白、Aβ1-42增高,可能对慢性酒精中毒的诊断有意义。(2)tau蛋白、Aβ1-42可能参与酒精致神经系统损害的机制。     

Tau蛋白与Alzheimer病

1 Tau的分子生物学 Tau蛋白由17号染色体长臂上的单基因编码,经可变剪接产生6种同型。成人脑可表达tau的6种异构,分别由352～441个不等的氨基酸构成,tau羧基末端可见1个重复片段,内含3～4个相同的氨基酸重复序列,每个序列由31～32个氨基酸残基组成。氨基末端含有1个29～58个氨基酸残基的插入序列,CSFtau蛋白形成不同的异构体。外周神经系统主要表达较大的tau异构体,其氨基末端插入254个氨     

毛喉萜对tau蛋白磷酸化及聚集的影响

目的:本实验旨在细胞水平研究毛喉萜(forskolin)对tau蛋白磷酸化、聚集体形成及tau蛋白与微管结合能力的影响。方法:利用基因转染技术建立过度表达人类最长tau(tau441)的人肾母细胞瘤细胞(HEK293),免疫印迹技术检测细胞内tau蛋白的磷酸化状况,tau与微管结合能力改变;免疫荧光技术和thioflavin染色检测细胞内tau蛋白聚集体形成情况。结果:在HEK293转tau细胞株,总tau蛋白的表达没有明显改变,tau蛋白在Ser214、Ser262和Ser396/404位点过度磷酸化。与此同时,随着tau蛋白的过度磷酸化,tau蛋白与微管的结合能力下降,细胞内有磷酸化的tau蛋白聚集增加。结论:蛋白激酶A的激活可以引起tau蛋白的过度磷酸化,磷酸化的位点包括蛋白激酶A和非蛋白激酶A的磷酸化位点,而过度磷酸化的tau蛋白又损害了tau与微管结合,形成了大量细胞内聚集体,提示了蛋白激酶A的激活可能是超早期阿尔茨海默病病理发展过程的关键因素之一。     

MicroRNAs与阿尔茨海默病的研究进展

<正>阿尔茨海默病(Alzheimer’s disease,AD)是一种起病隐匿的进行性发展的神经系统退行性疾病。AD的发病机制目前尚不十分清楚,其典型的神经病理学改变是:β-淀粉样蛋白(amyloidβ,Aβ)沉积、过度磷酸化的微管相关蛋白tau及神经元的损伤和缺失等。microRNAs(miRNAs)是在真核生物中发现的一类内源性的具有调控功能的非编码RNA,可以指导沉默复合体降解靶信使核糖核酸(Messenger RNA,mR-     

tau蛋白正电子发射断层显像在阿尔茨海默病及其他神经退行性疾病中的研究进展

异常磷酸化的tau蛋白组成神经原纤维缠结(NFT)和β淀粉样蛋白(Aβ)聚集形成老年斑是阿尔茨海默病(AD)的主要病理改变。NFT负荷与神经元丢失、脑萎缩以及认知状况相关。正电子发射断层显像(PET)能客观显示活体脑内NFT的沉积量以及分布情况,在AD的诊断和病情评估方面具有重要参考价值。文中总结tau蛋白示踪剂的开发情况及其在AD和其他神经退行性疾病中的研究进展。     

Microtubule-associated protein tau gene: a risk factor in human neurodegenerative diseases

Tau is a microtubule-associated protein mainly expressed in neurons of central nervous system, which is crucial in the maintenance of these cells. It has a central role in the polymerization and stabilization of microtubules and in the traffic of organelles along axons and dendrites. Aggregates of hyperphosphorylated forms of tau protein participate in the formation of neurofibrillary tangles, which characterize numerous neurodegenerative disorders named tauopathies. The analysis of tau gene and the study of familial cases of tauopathies have led to the discovery of tau gene mutations that cause inherited dementia designated as Frontotemporal dementia (FTD) with parkinsonism linked to chromosome 17 (FTDP-17). However, these familial cases remain rare compared to the sporadic tauopathies, the later involving both genetic and environmental etiologic factors. As tau pathology represents a primary pathogenic event in various neurodegenerative diseases, the hypothesis that tau genotype could influence the development of these diseases was tested by several groups. This review summarizes advances in the molecular genetics of the tau gene, as well as recent studies addressing the disease incidence of novel tau polymorphisms in different neurodegenerative diseases. Hopefully, the identification of several genetic defects of the tau gene will be helpful in improving our understanding of the role of tau protein in the pathogenesis of various neurodegenerative diseases.     

Formation of Filamentous Tau Aggregations in Transgenic Mice Expressing V337M Human Tau

Formation of neurofibrillary tangles (NFTs) is the most common feature in several neurodegenerative diseases, including Alzheimer's disease (AD). Here we report the formation of filamentous tau aggregations having a beta-sheet structure in transgenic mice expressing mutant human tau. These mice contain a tau gene with a mutation of the frontotemporal dementia parkinsonism (FTDP-17) type, in which valine is substituted with methionine residue 337. The aggregation of tau in these transgenic mice satisfies all histological criteria used to identify NFTs common to human neurodegenerative diseases. These mice, therefore, provide a preclinical model for the testing of therapeutic drugs for the treatment of neurodegenerative disorders that exhibit NFTs.     

Tau protein in familial and sporadic diseases

Abnormal protein aggregation is a common characteristic of many neurodegenerative diseases of the brain. Filamentous deposits made of the microtubule-associated protein tau constitute a major defining characteristic of several neurodegenerative diseases known as tauopathies. The role of tau in neurodegeneration has been clarified by the identification of genetic mutations in the tau gene in cases with familial frontotemporal dementia and parkinsonism linked to chromosome 17. Furthermore, some sporadic tauopathies are associated with tau gene polymorphisms. Although it is still debated how tau gene mutations lead to neuronal death, it is clear that different mutations lead to tau pathologies with characteristics similar to those found in sporadic tauopathies. These findings have definitely shown that in tauopathies tau aggregation is directly associated with development of neurodegeneration and neuronal death.     

Transgenic zebrafish model of neurodegeneration

In Alzheimer's disease (AD), the microtubule-associated protein, tau, is compromised in its normal association with microtubules and forms into paired helical filaments (PHF) that are the hallmark cytoskeletal pathology of the disease. Several posttranslational modifications of tau including phosphorylation have been implicated in AD pathogenesis. In addition, and importantly, mutations in the genes encoding human tau have recently been implicated in a variety of hereditary dementias, collectively termed frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17). This has rekindled interest in the importance of tau in neurodegenerative diseases (cf. Vogel [1998] Science 280:1524-1525; Goedert et al. [1998] Neuron 21:955-958; D'Souza et al. [1999] PNAS 96:5598-5603). Despite significant progress in the field of tau biology and neurodegenerative diseases, several important issues remain unresolved. The early functional consequences of tau alterations in living neurons is incompletely understood, and it is not clear how tau in neurodegenerative diseases becomes redistributed from its normal concentration in neuronal axons to pathological inclusions in neuronal soma known as neurofibrillary tangles (NFT). One of the reasons for these gaps in knowledge is the relative paucity of model systems to study these processes. We have developed a transgenic model system to study the functional consequences and trafficking patterns in zebrafish neurons of human tau either mutated on sites associated with hereditary dementias or altered at select posttranslational modification sites. The overall guiding hypothesis is that the model allows dissection of a hierarchy of events relevant to potential mechanisms of neurodegenerative diseases related to critical early stages in development of disease. We showed that a FTDP-17 mutant form of human tau expressed in zebrafish neurons produced a cytoskeletal disruption that closely resembled the NFT in human disease. This model system will prove useful in the study of other mutant taus in vertebrate neurons in vivo, and the approaches developed here will have broad usefulness in the study of functional consequences and potential genetic analyses of introducing into living vertebrate neurons other molecules involved in the pathogenesis of neurodegenerative diseases.     

Intracellular processing of aggregated tau differs between corticobasal degeneration and progressive supranuclear palsy

Corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) are sporadic neurodegenerative diseases with intracytoplasmic aggregates of the microtubule-associated protein, tau, in neurons and glial cells. Immunoblot analysis of detergent-insoluble brain extracts of patients with CBD and PSP shows distinctive patterns of tau fragments. These results suggest differing intracellular processing of aggregated tau in these two diseases despite an identical composition of tau isoforms. Such biochemical differences may be related to the neuropathological features of these diseases.     

Tau pathology: a marker of neurodegenerative disorders

Tau is not only a basic component of neurofibrillary degeneration, but is also an aetiological factor, as demonstrated by mutations on the tau gene responsible for frontotemporal dementias with parkinsonism linked to chromosome 17. Polymorphisms on the tau gene and the hierarchical invasion of neocortical areas by tau pathology in numerous sporadic neurodegenerative diseases also suggest that tau pathology is a primary pathogenic event in non-familial dementing diseases and a lead for solid diagnostic and therapeutic approaches.     

Phospho-tau/total tau ratio in cerebrospinal fluid discriminates Creutzfeldt-Jakob disease from other dementias

Early clinical symptoms of sporadic Creutzfeldt-Jakob disease (CJD) may overlap with other neurodegenerative diseases like Alzheimer's disease (AD) and frontotemporal degeneration (FTD). On entering an era in which pharmaceutical treatment of CJD occurs, reliable diagnostic markers like immunodetection of 14-3-3 proteins in the cerebrospinal fluid (CSF) are required. However, false negative results in autopsy-proven, sporadic CJD cases, as well as false positive results in several other disorders including AD and FTD showing high CSF tau protein levels, limit the potential of this marker. Due to neuronal lysis the cytosolic fraction of total tau containing phosphorylated and non-phosphorylated isoforms is partially liberated into the CSF. Since hyperphosphorylation of tau may specifically occur in neurodegenerative diseases associated with neurofibrillary changes, we hypothesized that the phospho-tau (P-tau)/total tau ratio in CSF may be a useful marker to discriminate CJD from other neurodegenerative disorders. The P-tau/total tau ratio discriminated patients with CJD from all other neuro-degenerative disorders including patients with AD and FTD without any overlap. Although the results have to be confirmed in a larger sample, the preliminary data suggest that simultaneous measurement of total tau and P-tau in CSF may be useful to identify patients with CJD.     

Tau and tauopathies

Tau protein is a neuronal microtubule-associated protein (MAP), which localizes primarily in the axon. It is one of the major and most widely distributed MAPs in the central nervous system. Its biochemistry and molecular pathology is being increasingly studied. Tau is a key component of neurofbrillary tangles in Alzheimer's disease (AD). Disorders with neuronal, oligodendroglial or astrocytic filamentous tau inclusions are now grouped under the common rubric of tauopathies. The discovery of mutations in the tau gene, located on Chromosome 17 and its relationship to frontotemporal dementia with Parkinsonism (FTDP-17) has enhanced the importance of tau protein in cognitive neurology. Aberrant aggregates of tau have been documented in most of the neurodegenerative diseases with filamentous inclusions. The role of cerebrospinal fluid tau in the diagnosis of dementias is being investigated quite extensively. Recently, it has been shown that Abeta immunotherapy leads to the clearance of early tau pathology. It is becoming clearer that understanding tau better will lead to better understanding of many neurodegenerative diseases that may help develop interventional strategies.     

Tau in neurodegenerative diseases: Tau phosphorylation and assembly

The possible link between tau phosphorylation and tau assembly in these neurodegenerative diseases known as tauopathies is described. Additionally, this link is supported by an in vitro experiment showing the higher capacity of phosphotau to assemble in some specific conditions; and, by a recently reported experiment using a tau transgenic mouse model.     

Microtubule-associated protein tau, heparan sulphate and α-synuclein in several neurodegenerative diseases with dementia

Microtubule-associated protein tau forms neurofibrillary lesions in Alzheimer’s disease and several other neurodegenerative disorders, such as Niemann-Pick disease type C, subacute sclerosing panencephalitis, argyrophilic grain disease, myotonic dystrophy and motor neuron disease with neurofibrillary tangles. In this study we have compared the characteristics of tau pathology in these diseases using immunohistochemistry and phosphorylation-dependent and phosphorylation-independent anti-tau antibodies. The pattern of staining for heparan sulphate and α-synuclein was also investigated. We show that in all of these diseases tau deposits were stained by all anti-tau antibodies used, with the exception of argyrophilic grains which do not stain with antibody 12E8, confirming our previous findings. Heparan sulphate staining was present to a variable extent in all of these diseases, with the exception of subacute sclerosing panencephalitis, in which no staining was observed. Heparan sulphate staining coexisted with tau staining. In some cases it was more extensive than the tau staining. α-Synuclein staining was present in presynaptic terminals with the exception of one case of Alzheimer’s disease, in which α-synuclein-positive Lewy bodies were observed in the hippocampal formation. These findings indicate that tau deposits are antigenically similar in several neurodegenerative diseases and that tau staining is often associated with heparan sulphate staining, supporting the concept that heparan sulphate may be involved in the assembly of tau protein into filaments. Received: 14 August 1998 / Revised, accepted: 12 November 1998