Pick病的蛋白质组研究

目的为深入理解Pick病分子机制并寻找诊断治疗该疾病的蛋白质标记物，选取3例经病理证实的Pick病患者与4例正常老年人尸检脑标本进行蛋白质组学研究。方法死亡24h内新鲜取材的尸检额叶、颞叶蛋白质以固相pH梯度等电聚焦为第一向，十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）为第二向进行双向电泳（2-DE），图像分析软件Image Master 2D Elite分析电泳图谱，基质辅助激光解析／电离-飞行时间（MALDI-TOF）质谱或MALDI-TOF／TOF串联质谱鉴定蛋白质。结果15种蛋白质的表达量在Pick病患者与正常老年人显著不同。8个在Pick病表达量上调的蛋白质被鉴定为热休克蛋白60、Mn超氧化物歧化酶、α-烯醇化酶、3-磷酸甘油醛脱氢酶、胶质纤维酸性蛋白、硫氧还蛋白过氧化物酶1、RNA结合蛋白调节亚基、P25α；7个在Pick病表达量下调的蛋白质被鉴定为pemxiredoxin 5、cofilin、铁蛋白H链、血清白蛋白前体、二氢嘧啶酶相关蛋白2、丙酮酸激酶、碳酰还原酶[NADPH]1。结论氧自由基与抗氧化蛋白的平衡受损及重要代谢酶、神经原纤维缠结相关蛋白的变化同Pick病发病密切相关。     

皮质基底节变性患者的蛋白质组研究

目的 探讨皮质基底节变性的分子机制并寻找诊断治疗该疾病的蛋白质标记物.方法 尸检来自解放军总医院死亡24 h内、经病理证实的男性皮质基底节变性患者(4例)脑及无神经系统疾患的正常老年男性(4例)脑组织,额叶、颞叶和纹状体部位取材,应用HE染色、Gallyas-Braak银染色和Tau蛋白免疫组织化学染色观察皮质基底节变性患者的脑组织学改变;额叶部位取材,以固相pH梯度等电聚焦为第一向,SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)电泳为第二向进行双向电泳,分析电泳图谱后采用MALDI-TOFTOF串联质谱仪进行蛋白质的鉴定.结果 HE染色显示皮质基底节变性患者额叶神经元明显脱失,伴胶质细胞大量增生,Gallyas-Braak和Tau免疫组化染色结果显示纹状体中大量球形团样缠结;与正常老年人脑组织比较,皮质基底节变性患者脑组织9个蛋白表达增加(经鉴定为coflin、尿嘧啶DNA糖苷水解酶、Cu-Zn超氧化物歧化酶、异柠檬酸脱氢酶亚单位、突触结合蛋白Ⅰ、硫氧还蛋白过氧化物酶1、胶质纤维酸性蛋白、P25alpha、Peroxircdoxin 5),5个蛋白表达下降(经鉴定为碳酰还原酶[NADPH]1、铁蛋白H链、肽基脯氨酸顺反异构酶A、血清白蛋白前体、二氢嘧啶酶相关蛋白2),差异有统计学意义(P＜0.05).结论 上述差异蛋白有助于探讨皮质基底节变性的分子机制及其早期诊断和新药开发.

Abstract：

Objective To investigate the molecular mechanism of corticobasal degeneration and search the protein markers ofdiagnoseis and treatment of this disease. Methods The brains of subjects died without clinical or pathological involvement of nervous system (n=4) and brains of patients with corticobasal degeneration (n=4) were obtained at autopsy. Tissues samples were cut from the frontal and temporal lobes, and the striatum. Histological changes of the tissue samples were observed by HE staining, Gallyas-Braak silver staining and Tau protein immunohistochemistry. The samples extracted from the frontal lobe were performed dimensional electrophoresis with immobilized pH gradient (IPG)isoelectric focusing electrophoresis as the first dimension and with vertical sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) as the second dimension; the maps were visualized by Coomassie brilliant blue staining and analyzed with ImageMaster 2D Elite software; the protein profiles were in-gel digested and identified by mass spectrometry (MALDI-TOFTOF). Results Significant neuron loss in the temporal lobe of patients with corticobasal degeneration was noted by HE staining, with mass proliferation of gliocyte in the temporal lobe; sphere-like entanglement in the striatum was noted by Gallyas-Braak silver staining and Tau immunohistochemistry. Fourteen protein spots in the brains of patients with corticobasal degeneration were differentially expressed as compared with those in age-matched nondemented control brains; the expression of 9 proteins (cofilin, uracil DNA glycosylase,Cu-Zn superoxide dismutase, isocitrate dehydrogenase subunit, synaptotagmin Ⅰ, thioredoxin peroxidase 1, glial fibrillary acidic protein, P25 alpha and peroxiredoxin 5) in brains of patients with corticobasal degeneration was up-regulated as compared with that in the normal brain tissue (P＜0.05); the expression of 5 proteins (carbonyl reductase [NADPH] 1, ferritin heavy chain, peptidyl-prolyl cis-trans isomerase A,serum albumin precursor and dihydropyrimidinase-related protein 2) in brains of patients with corticobasal degeneration was down-regulated as compared with that in the normal brain tissues (P＜0.05).Conclusion We get a number of related-proteins of corticobasal degeneration. Some proteins are quite useful in discovering the molecular mechanisms of corticobasal degeneration and may be helpful in the ealry diagnosis and treatment of corticobasal degeneration and in the development of new medicine.     

Proteomic comparison between human young and old brains by two-dimensional gel electrophoresis and identification of proteins

To investigate molecular mechanisms of human brain aging, brain proteins were isolated from postmortem human young and old brains and profiled by two-dimensional gel electrophoresis (2-DE). With the help of special software, five down-regulated protein spots in two-dimensional gel electrophoresis gels of old brains were found compared with young brains, four of which was identified as a protein similar to peroxiredoxin 2 (accession-numbered as gi | 13631440), two of stathmin (phosphoprotein p19) and apolipoprotein A-I precursor (apo-AI) by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Eight common proteins, whose expressions were not altered between young and old brains, were also identified. The possible relevance of changes was analyzed. This study shows that the contribution of proteomics could be valuable in experimental gerontology field.     

Molecular mechanisms of the co‐deposition of multiple pathological proteins in neurodegenerative diseases

Intracellular inclusions composed of abnormal protein aggregates are one of the neuropathological features of neurodegenerative diseases, and the formation of intracellular aggregates is believed to be associated with neurodegeneration leading to the onset of these diseases. In typical or pure cases, characteristic pathologies with one particular protein, such as tau, alpha‐synuclein or trans‐activation response DNA protein 43 (TDP‐43), can be observed in brains of patients. On the other hand, multiple protein pathologies co‐exist in many cases, raising the possibility that they may influence each other reciprocally in the pathogenesis and progression of the diseases. However, the molecular mechanisms through which these proteins interact with each other and through which they are co‐deposited in brains of patients remain poorly understood. In this review, we focus on the mechanisms of deposition of multiple pathological proteins, such as tau, alpha‐synuclein and/or TDP‐43, and on co‐deposition models of these proteins in vitro and in vivo intended to recapitulate the multiple pathologies found in diseased brains.     

Molecular chaperone-mediated tau protein metabolism counteracts the formation of granular tau oligomers in human brain

Intracellular accumulation of filamentous tau proteins is a defining feature of neurodegenerative diseases termed tauopathies. The pathogenesis of tauopathies remains largely unknown. Molecular chaperones such as heat shock proteins (HSPs), however, have been implicated in tauopathies as well as in other neurodegenerative diseases characterized by the accumulation of insoluble protein aggregates. To search for in vivo evidence of chaperone-related tau protein metabolism, we analyzed human brains with varying degrees of neurofibrillary tangle (NFT) pathology, as defined by Braak NFT staging. Quantitative analysis of soluble protein levels revealed significant positive correlations between tau and Hsp90, Hsp40, Hsp27, alpha-crystallin, and CHIP. An inverse correlation was observed between the levels of HSPs in each specimen and the levels of granular tau oligomers, the latter of which were isolated from brain as intermediates of tau filaments. We speculate that HSPs function as regulators of soluble tau protein levels, and, once the capacity of this chaperone system is saturated, granular tau oligomers form virtually unabated. This is expressed pathologically as an early sign of NFT formation. The molecular basis of chaperone-mediated protection against neurodegeneration might lead to the development of therapeutics for tauopathies. (c) 2007 Wiley-Liss, Inc.     

Proteomic 2-D DIGE profiling of APP23 transgenic mice brain from pre-plaque and plaque phenotypes

Alzheimer's disease is the most prevalent form of dementia associated with aging in the human population for which there is no biomarker for accurate and effective diagnosis at its early stage or monitoring of disease progression. In this study, we used 2-D DIGE to identify Alzheimer's disease-related proteins in the brains of APP23 mice used as a model for studying cerebral amyloidosis. Protein expression profiles in the brain of 2- and 24-month old female transgenic mice, displaying pre-plaque and plaque phenotypes, respectively, and 24-month old wild-type mice were compared to identify if changes at the protein level could be implicated in the early molecular events leading to cerebral amyloidosis. Seven such proteins were identified including kinesin heavy chain, dihydropyrimidinase related protein 2, beta-tubulin, two isomers of 3-phosphoglycerate dehydrogenase, ubiquinol cytochrome c reductase, and heat shock protein 84. The dysregulation of these proteins may have implications on pathways such as the mitochondrial respiratory chain, axonal transport, axon guidance, L-Serine biosynthesis and cytoskeletal reorganization, and thereby may represent events that precede and participate in the formation of senile plaque. Other detected protein changes were observed only in the plaque phenotype, and so are likely to be a consequence of plaque deposition and/or associated with neurodegenerative/repair processes. These proteins provide a basis for further dissecting the early mechanisms of Alzheimer's disease, and exploring their implications as relevant biomarker candidates of incipient Alzheimer's disease and progression in man.     

Animal models of tauopathies

Intracellular fibrillar amyloid lesions comprised of tau proteins are pathological hallmarks in diverse neurodegenerative disorders. As models of these tauopathies, transgenic mice overexpressing tau with or without mutations discovered in familial tauopathies were generated. Findings in these tau transgenic mice support the notion that impairments of tau proteins are causally related to tauopathies, while studies on crossbred mice have indicated initiation and promotion of tau‐positive neuropathologies by cross‐talk among several pathogenic molecules. Enhancement of tau pathology by amyloid β (Aβ) deposition provided some of the most compelling evidence for such a cross‐talk, and molecular processes linking abnormalities of Aβ and tau have been suggested to involve activation of calcium‐dependent protease, calpain, based on analyses of amyloid precursor protein transgenic mice crossbred with other genetically engineered mice with altered calpain activity. It also should be noted that mice transgenic for both tau and α‐synuclein exhibit facilitated polymerization of these molecules into pathological filaments. Roles of fibrillar tau deposits in nervous system injuries can be mechanistically pursued by longitudinal monitoring of brain amyloidosis and neuroglial degeneration in the time course of antiamyloid intervention. The possibility of in vivo detection of tau‐positive amyloid lesions has been demonstrated by intravenous administration of potential tracers into tau transgenic mice and subsequent brain imaging. Moreover, visualization of glial responses in living brains may allow sensitive detection of degenerative changes in the central nervous system.     

Avid Binding of βA Amyloid Peptide to Its Own Precursor

The senile plaque and congophilic angiopathy in brains of patients with Alzheimer's disease contain abnormal extracellular depositions. These depositions have very complex molecular structure, some elements of which have been identified. The most abundant protein in these structures is βA amyloid peptide, which is produced by proteolytic processing of a larger protein, the amyloid precursor protein. It is not known how plaques and angiopathy are formed. Binding of proteins with the βA peptide may be critical in this process. Using synthetic βA peptides we show that the amyloid precursor protein found in cerebrospinal fluid binds βA peptide with high avidity. Analysis of recombinant amyloid precursor proteins containing deletions of various domains demonstrate that the βA peptide binds to the amino terminus of its own precursor. A model of plaque assembly is presented.     

Identification of nitrated proteins in Alzheimer's disease brain using a redox proteomics approach

Nitric oxide (NO) has been implicated in the pathophysiology of a number of neurodegenerative diseases including Alzheimer's disease (AD). In the present study, using a proteomics approach, we identified enolase, glyceraldehyde-3-phosphate dehydrogenase, ATP synthase alpha chain, carbonic anhydrase-II, and voltage-dependent anion channel-protein as the targets of nitration in AD hippocampus, a region that shows a extensive deposition of amyloid beta-peptide, compared with the age-matched control brains. Immunoprecipitation and Western blotting techniques were used to validate the correct identification of these proteins. Our results are discussed in context of the role of oxidative stress as one of the important mechanisms of neurodegeneration in AD.     

Human c-Jun N-terminal kinase expression and activation in the nervous system

Differential expression and localization of c-Jun N-terminal kinases (JNKs) in the human brain may reflect transduction of a variety of extracellular stimuli to selective cellular responses. Of the three JNKs, JNK1 and 2 are widely distributed in tissues and JNK3 is predominantly restricted to brain where it is expressed in neurons. Although there is considerable molecular conservation among all three JNKs, we distinguished expression of each by in situ hybridization, immunoblot analysis with a panel of antibodies, and stress-activation using c-Jun as substrate. In the human central nervous system (CNS), there are at least 10 isoforms: JNK3alpha1 and JNK1alpha1 were the major JNK isoforms expressed; JNK2 was not detected. On immunoblots of brain homogenates, antibody selectivity identified JNK3alpha1 as a 45-kDa protein, JNK1alpha1, a slightly lower band at 44 kDa, and a 50-kDa band of unknown specificity. Recombinant human JNK3alpha1, transfected either into CHO, COS-1, or Neuro2A (N2A) cells, was strongly expressed as a 45-kDa protein in each. Transfected JNK3alpha1, and endogenous JNK1, each immunoprecipitated from N2A cells, phosphorylated recombinant forms of human c-Jun. Kinase activity of each JNK was modestly stimulated in N2A cells by anisomycin but not by ceramide, UV irradiation, or heat shock. Endogenous JNK activation, especially at a low level, may reflect a chronic and cumulative stress process that contributes to hyperphosphorylation of cytoskeletal proteins such as those found in Alzheimer's disease (AD), and ultimately, induction of apoptosis.     

Accumulation of a repulsive axonal guidance molecule RGMa in amyloid plaques: a possible hallmark of regenerative failure in Alzheimer's disease brains

J. Satoh, H. Tabunoki, T. Ishida, Y. Saito and K. Arima (2013) Neuropathology and Applied Neurobiology 39, 109–120 Accumulation of a repulsive axonal guidance molecule RGMa in amyloid plaques: a possible hallmark of regenerative failure in Alzheimer's disease brains Aims: RGMa is a repulsive guidance molecule that induces the collapse of axonal growth cones by interacting with the receptor neogenin in the central nervous system during development. It remains unknown whether RGMa plays a role in the neurodegenerative process of Alzheimer's disease (AD). We hypothesize that RGMa, if it is concentrated on amyloid plaques, might contribute to a regenerative failure of degenerating axons in AD brains. Methods: By immunohistochemistry, we studied RGMa and neogenin (NEO1) expression in the frontal cortex and the hippocampus of 6 AD and 12 control cases. The levels of RGMa expression were determined by qRT‐PCR and Western blot in cultured human astrocytes following exposure to cytokines and amyloid beta (Aβ) peptides. Results: In AD brains, an intense RGMa immunoreactivity was identified on amyloid plaques and in the glial scar. In the control brains, the glial scar and vascular foot processes of astrocytes expressed RGMa immunoreactivity, while oligodendrocytes and microglia were negative for RGMa. In AD brains, a small subset of amyloid plaques expressed a weak NEO1 immunoreactivity, while some reactive astrocytes in both AD and control brains showed an intense NEO1 immunoreactivity. In human astrocytes, transforming growth factor beta‐1 (TGFβ₁), Aβ_1–40 or Aβ_1–42 markedly elevated the levels of RGMa, and TGFβ₁ also increased its own levels. Coimmunoprecipitation analysis validated the molecular interaction between RGMa and the C‐terminal fragment β of amyloid beta precursor protein (APP). Furthermore, recombinant RGMa protein interacted with amyloid plaques in situ. Conclusions: RGMa, produced by TGFβ‐activated astrocytes and accumulated in amyloid plaques and the glial scar, could contribute to the regenerative failure of degenerating axons in AD brains.     

Variations in platelet protein associated with arterial thrombosis

INTRODUCTION: Hyperactivity of platelets has been associated with thrombotic episodes by molecular mechanisms not yet elucidated. The present work aimed at identifying whether the platelet protein content from patients who had suffered an arterial thrombosis episode differed from that of platelets obtained from normal healthy donors. METHODS: Differential platelet protein profiles were determined by 2-dimensional (2-D) gel electrophoresis and Western blot analysis of total platelet lysates. Identification of differentially expressed proteins was carried out by mass spectrometry (MALDI-TOF). RESULTS: We found a decreased platelet content of three protein spots in patients of arterial thrombosis: integrin linked kinase (ILK), fructose bisphosphate aldolase (aldolase) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) whereas the content of four other protein spots was increased: actin binding protein, coronine like (p57), non-muscle myosin heavy chain (NMMHC-A), pyruvate kinase M2 isoenzyme (PK) and phosphoglycerate kinase (PGK). The variations in ILK, GAPDH and PK were validated by Western blot analysis. The proteins showing a decreased platelet content in arterial thrombosis patients are associated with the cytoskeletal insoluble fraction and the detected increase in some proteins seems to be due to the generation of peptides caused by a limited proteolysis. Differences in the protein profiles of circulating platelets from arterial thrombosis were maintained months after the acute thrombotic event and disappear in the long term. CONCLUSIONS: The observed variations in some platelet proteins suggest the existence of a perturbation in the cytoskeletal organization and increased proteolysis, both indicative of a platelet pro-active state, persistent after the thrombotic event.     

Overexpression of myosin-IIB in the brain of a rat model of streptozotocin-induced diabetes

The Ca(2+)/calmodulin complex interacts with and regulates various enzymes and target proteins known as calmodulin-binding proteins (CaMBPs). This group of proteins includes molecular motors such as myosins. In this study, we show that non-muscle myosin-IIB is overexpressed in the brains of diabetic rats. We isolated CaMBPs from the brains of non-diabetic rats and rats with streptozotocin-induced diabetes and purified them by immobilized-calmodulin affinity chromatography. The proteins were eluted with EGTA and urea, separated by SDS-PAGE, digested and submitted to peptide mass fingerprinting analysis. Thirteen intense bands were found in both types of brains, two were found exclusively in non-diabetic brains and four were found exclusively in diabetic brains. A large fraction of the eluted proteins contained putative IQ motifs or calmodulin-binding sites. The results of the myosin-IIB affinity chromatography elution, western blot and RT-PCR analyses suggest that myosin-IIB protein and mRNA are expressed at high levels in diabetic brains. This is the first study that has demonstrated differential expression of CaMBPs in diabetic and non-diabetic brain tissue through a comparative proteomic analysis, and it opens up a new approach to studying the relationship between the expression of myosins in the brain, hyperglycemia and intracellular calcium regulation.     

Expression of BRI2 mRNA and protein in normal human brain and familial British dementia: its relevance to the pathogenesis of disease

Introduction: Two different disease‐specific mutations in the BRI2 gene, situated on chromosome 13, have been identified as giving rise to familial British dementia (FBD) and familial Danish dementia (FDD). Each mutation results in extension of the open reading frame generating the disease‐specific precursor proteins which are cleaved by furin‐like proteolysis releasing the amyloidogenic C‐terminal peptides ABri and ADan in FBD and FDD, respectively. Material and methods: To understand the mechanism of the formation of amyloid lesions in FBD, we studied the origin of the precursor proteins and furin in the human brain. We used control brains, cases of sporadic Alzheimer's disease (AD), variant AD with cotton wool plaques and FBD to study BRI2 mRNA expression using in situ hybridization. Furin and BRI2 protein expression was investigated using Western blotting and immunohistochemistry. Results: BRI2 mRNA and BRI2 protein are widely expressed primarily by neurones and glia and are deposited in the amyloid lesions in FBD. They were, however, not expressed by cerebrovascular components. Furin expression showed a similar pattern except that it was also present in cerebrovascular smooth muscle cells. Conclusions: These findings suggest that neurones and glia and are a major source of BRI2 protein and that in FBD, the mutated precursor protein may undergo furin cleavage within neurones to produce the amyloid peptide ABri. The failure to demonstrate BRI2 in blood vessels under the conditions tested suggests that vascular amyloid peptide production does not contribute significantly to cerebral amyloid angiopathy (CAA) in FBD and FDD, lending indirect support to the drainage hypothesis of CAA.     

Tau alternative splicing and frontotemporal dementia

A number of neurodegenerative diseases are characterized by the presence of abundant deposits containing Tau protein. Expression of the human tau gene is under complex regulation. Mutations in the tau gene have been identified in patients with frontotemporal lobe dementia. These mutations affect either biochemical/biophysical properties or the delicate balance of different splicing isoforms. In this review, we summarize recent advances in our understanding of genetics and molecular pathogenesis of tauopathies with the focus on frontotemporal lobe dementia. We review published studies on tau pre-mRNA splicing regulation. Understanding molecular mechanisms of tauopathies may help in developing effective therapies for neurodegenerative tauopathies and related disorders, including Alzheimer disease.     

X11 alpha and x11 beta interact with presenilin-1 via their PDZ domains

X11 alpha and X11 beta are two neuronal adaptor proteins that interact with the Alzheimer's disease amyloid precursor protein (APP). X11 alpha and X11 beta stabilise APP and inhibit production of proteolytic APP fragments including the A beta peptide that is deposited in the brains of Alzheimer's disease patients. The mechanisms by which X11 alpha and X11 beta modulate APP processing are not clear but one possibility is that they influence the activity of the secretases that cleave APP to give rise to A beta. Presenilin-1 is required for gamma-secretase activity and here we demonstrate that both X11 alpha and X11 beta interact with presenilin-1. X11/presenilin-1 binding is via two X11 PDZ domains and sequences within the carboxy-terminus of presenilin-1. We also demonstrate that both X11 alpha and X11 beta mediate the formation of complexes between APP and presenilin-1. These results suggest that the X11 regulation of APP processing is controlled, at least in part, via their interactions with APP and presenilin-1.     

Clinical correlations in 16 patients with total or partial laminin alpha2 deficiency characterized using antibodies against 2 fragments of the protein

BACKGROUND: Many patients with classic congenital muscular dystrophy have been found to have partial or total deficiency of the alpha2 chain of laminin 2 (merosin). This deficiency has mostly been studied using only 1 antibody against a fragment of the protein. OBJECTIVES: To characterize the expression of laminin alpha2 in the skeletal muscle of patients with laminin alpha2 deficiency using antibodies against 2 different portions of the protein and to correlate the immunochemical findings with clinical phenotype. METHODS: We studied 4 patients with total lack of laminin alpha2 and 12 with partial laminin alpha2 deficiency with immunohistochemical techniques and Western blot analysis. We used antibodies recognizing an 80-kd fragment toward the C-terminus and a 300-kd fragment toward the amino-terminal. Patient characteristics examined were functional compromise, magnetic resonance imaging or computed tomography of the brain, electromyography, evoked potentials, and creatine kinase levels. RESULTS: In 4 patients, immunohistochemical analysis revealed no reactivity to either antibody; in 2 patients, the 300-kd fragment alone was partially expressed; in 2 patients, the 80-kd fragment alone was partially expressed; and in 8 patients, both fragments were partially expressed. Immunoblot analysis revealed bands of reduced intensity and normal molecular weight generally corresponding to the immunohistochemical findings. Absence of both fragments or of one with reduction of the other always produced a severe clinical phenotype, while a milder clinical phenotype was observed when both fragments were partially expressed. CONCLUSIONS: Extent of laminin alpha2 deficiency in most cases correlates with clinical phenotype but not with peripheral and central white matter abnormalities. Skin biopsy specimens may reveal laminin alpha2 deficiency in patients who have normal laminin alpha2 levels in muscle biopsy specimens.