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Sample records for amyloid precursor protein

  1. Copper Promotes the Trafficking of the Amyloid Precursor Protein*

    OpenAIRE

    Acevedo, Karla M.; Hung, Ya Hui; Dalziel, Andrew H.; Li, Qiao-Xin; Laughton, Katrina; Wikhe, Krutika; Rembach, Alan; Roberts, Blaine; Masters, Colin L.; Ashley I. Bush; Camakaris, James

    2010-01-01

    Accumulation of the amyloid β peptide in the cortical and hippocampal regions of the brain is a major pathological feature of Alzheimer disease. Amyloid β peptide is generated from the sequential protease cleavage of the amyloid precursor protein (APP). We reported previously that copper increases the level of APP at the cell surface. Here we report that copper, but not iron or zinc, promotes APP trafficking in cultured polarized epithelial cells and neuronal cells. In SH-SY5Y neuronal cells ...

  2. Amyloid Precursor Protein Processing in Alzheimer’s Disease

    Directory of Open Access Journals (Sweden)

    Adwait BHADBHADE

    2012-03-01

    Full Text Available How to Cite this Article: Bhadbhade A, Cheng DW. Amyloid Precursor Protein Processing in Alzheimer’s Disease. Iranian Journal of Child Neurology2012;6(1:1-5.Alzheimer’s disease (AD is a progressive neurodegenerative disorder and a leading cause of dementia. The AD is characterized by presence of intraneuronal tangles and extracellular plaques in the brain. The plaques are composed of dense and mostly insoluble deposits of amyloid beta peptide (Aβ, formed by sequential cleavage of the Amyloid Precursor Protein (APP, by two pathways amyloidogenic and non-amyloidogenic. Tangles are composed of paired helical fragments, which aggregate to form, microtubular protein tau. Although Aβ plaques are established to be the cause of the disease, there exist genetic factors and other pathological identifications in addition to these which are an integral part of the disease. This article gives an overview into the mechanism of APP action, genetic factors and other pathological identifications contributing to Alzheimer’s disease formation.References Brookmeyer R, Gray S, Kawas C. Projections of Alzheimer’s disease in the United States and the public health impact of delaying disease onset. American Journal of Public Health 1998;88(9:1337. Hebert LE, Scherr PA, Bienias JL, Bennett DA, Evans DA. Alzheimer disease in the US population. Arch Neurol 2003;60(8:1119-22. Möller HJ, Graeber M. The case described by Alois Alzheimer in 1911. European Archives of Psychiatry and Clinical Neuroscience 1998:248(3:111-122. Selkoe D J. (2002. Deciphering the genesis and fate of amyloid beta-protein yields novel therapies for Alzheimer disease. J Clinic Investigat 2002;110(10: 1375-82. Wolfe MS. Tau mutations in neurodegenerative diseases. J Biolog Chem 2009;284(10:6021. Selkoe DJ. Alzheimer’s disease: genes, proteins, and therapy. Physiological reviews 2001;81(2:741. Selkoe DJ. The cell biology of [beta]-amyloid precursor protein and presenilin in Alzheimer

  3. AMYPdb: A database dedicated to amyloid precursor proteins

    Directory of Open Access Journals (Sweden)

    Delamarche Christian

    2008-06-01

    Full Text Available Abstract Background Misfolding and aggregation of proteins into ordered fibrillar structures is associated with a number of severe pathologies, including Alzheimer's disease, prion diseases, and type II diabetes. The rapid accumulation of knowledge about the sequences and structures of these proteins allows using of in silico methods to investigate the molecular mechanisms of their abnormal conformational changes and assembly. However, such an approach requires the collection of accurate data, which are inconveniently dispersed among several generalist databases. Results We therefore created a free online knowledge database (AMYPdb dedicated to amyloid precursor proteins and we have performed large scale sequence analysis of the included data. Currently, AMYPdb integrates data on 31 families, including 1,705 proteins from nearly 600 organisms. It displays links to more than 2,300 bibliographic references and 1,200 3D-structures. A Wiki system is available to insert data into the database, providing a sharing and collaboration environment. We generated and analyzed 3,621 amino acid sequence patterns, reporting highly specific patterns for each amyloid family, along with patterns likely to be involved in protein misfolding and aggregation. Conclusion AMYPdb is a comprehensive online database aiming at the centralization of bioinformatic data regarding all amyloid proteins and their precursors. Our sequence pattern discovery and analysis approach unveiled protein regions of significant interest. AMYPdb is freely accessible 1.

  4. Betaine suppressed Aβ generation by altering amyloid precursor protein processing.

    Science.gov (United States)

    Liu, Xiu-Ping; Qian, Xiang; Xie, Yue; Qi, Yan; Peng, Min-Feng; Zhan, Bi-Cui; Lou, Zheng-Qing

    2014-07-01

    Betaine was an endogenous catabolite of choline, which could be isolated from vegetables and marine products. Betaine could promote the metabolism of homocysteine in healthy subjects and was used for hyperlipidemia, coronary atherosclerosis, and fatty liver in clinic. Recent findings shown that Betaine rescued neuronal damage due to homocysteine induced Alzheimer's disease (AD) like pathological cascade, including tau hyperphosphorylation and amyloid-β (Aβ) deposition. Aβ was derived from amyloid precursor protein (APP) processing, and was a triggering factor for AD pathological onset. Here, we demonstrated that Betaine reduced Aβ levels by altering APP processing in N2a cells stably expressing Swedish mutant of APP. Betaine increased α-secretase activity, but decreased β-secretase activity. Our data indicate that Betaine might play a protective role in Aβ production.

  5. Therapeutic Potential of Secreted Amyloid Precursor Protein APPsα

    Science.gov (United States)

    Mockett, Bruce G.; Richter, Max; Abraham, Wickliffe C.; Müller, Ulrike C.

    2017-01-01

    Cleavage of the amyloid precursor protein (APP) by α-secretase generates an extracellularly released fragment termed secreted APP-alpha (APPsα). Not only is this process of interest due to the cleavage of APP within the amyloid-beta sequence, but APPsα itself has many physiological properties that suggest its great potential as a therapeutic target. For example, APPsα is neurotrophic, neuroprotective, neurogenic, a stimulator of protein synthesis and gene expression, and enhances long-term potentiation (LTP) and memory. While most early studies have been conducted in vitro, effectiveness in animal models is now being confirmed. These studies have revealed that either upregulating α-secretase activity, acutely administering APPsα or chronic delivery of APPsα via a gene therapy approach can effectively treat mouse models of Alzheimer’s disease (AD) and other disorders such as traumatic head injury. Together these findings suggest the need for intensifying research efforts to harness the therapeutic potential of this multifunctional protein.

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

    Institute of Scientific and Technical Information of China (English)

    Runzhong Liu; Haibo Hou; Xuelian Yi; Shanwen Wu; Huan Zeng

    2013-01-01

    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 γ-secretase. To further elucidate the roles of beta-site amyloid precursor protein-cleaving enzyme 1 in the development of Alzheimer'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.

  7. Amyloid precursor protein is trafficked and secreted via synaptic vesicles.

    Directory of Open Access Journals (Sweden)

    Teja W Groemer

    Full Text Available A large body of evidence has implicated amyloid precursor protein (APP and its proteolytic derivatives as key players in the physiological context of neuronal synaptogenesis and synapse maintenance, as well as in the pathology of Alzheimer's Disease (AD. Although APP processing and release are known to occur in response to neuronal stimulation, the exact mechanism by which APP reaches the neuronal surface is unclear. We now demonstrate that a small but relevant number of synaptic vesicles contain APP, which can be released during neuronal activity, and most likely represent the major exocytic pathway of APP. This novel finding leads us to propose a revised model of presynaptic APP trafficking that reconciles existing knowledge on APP with our present understanding of vesicular release and recycling.

  8. Altered β-Amyloid Precursor Protein Isoforms in Mexican Alzheimer’s Disease Patients

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    V. J. Sánchez-González

    2006-01-01

    Full Text Available Objective: To determine the β-amyloid precursor protein (βAPP isoforms ratio as a risk factor for Alzheimer’s Disease and to assess its relationship with demographic and genetic variables of the disease.

  9. B-Amyloid Precursor Protein Staining of the Brain in Sudden Infant and Early Childhood Death

    DEFF Research Database (Denmark)

    Jensen, Lisbeth Lund; Banner, Jytte; Ulhøi, Benedicte Parm

    2013-01-01

    To develop and validate a scoring method for assessing β-amyloid precursor protein (APP) staining in cerebral white matter and to investigate the occurrence, amount and deposition pattern based on the cause of death in infants and young children.......To develop and validate a scoring method for assessing β-amyloid precursor protein (APP) staining in cerebral white matter and to investigate the occurrence, amount and deposition pattern based on the cause of death in infants and young children....

  10. Amyloid precursor-like protein 1 (APLP1) exhibits stronger zinc-dependent neuronal adhesion than amyloid precursor protein and APLP2.

    Science.gov (United States)

    Mayer, Magnus C; Schauenburg, Linda; Thompson-Steckel, Greta; Dunsing, Valentin; Kaden, Daniela; Voigt, Philipp; Schaefer, Michael; Chiantia, Salvatore; Kennedy, Timothy E; Multhaup, Gerhard

    2016-04-01

    The amyloid precursor protein (APP) and its paralogs, amyloid precursor-like protein 1 (APLP1) and APLP2, are metalloproteins with a putative role both in synaptogenesis and in maintaining synapse structure. Here, we studied the effect of zinc on membrane localization, adhesion, and secretase cleavage of APP, APLP1, and APLP2 in cell culture and rat neurons. For this, we employed live-cell microscopy techniques, a microcontact printing adhesion assay and ELISA for protein detection in cell culture supernatants. We report that zinc induces the multimerization of proteins of the amyloid precursor protein family and enriches them at cellular adhesion sites. Thus, zinc facilitates the formation of de novo APP and APLP1 containing adhesion complexes, whereas it does not have such influence on APLP2. Furthermore, zinc-binding prevented cleavage of APP and APLPs by extracellular secretases. In conclusion, the complexation of zinc modulates neuronal functions of APP and APLPs by (i) regulating formation of adhesion complexes, most prominently for APLP1, and (ii) by reducing the concentrations of neurotrophic soluble APP/APLP ectodomains. Earlier studies suggest a function of the amyloid precursor protein (APP) family proteins in neuronal adhesion. We report here that adhesive function of these proteins is tightly regulated by zinc, most prominently for amyloid precursor-like protein 1 (APLP1). Zinc-mediated APLP1 multimerization, which induced formation of new neuronal contacts and decreased APLP1 shedding. This suggests that APLP1 could function as a zinc receptor processing zinc signals to stabilized or new neuronal contacts.

  11. Amyloid precursor protein modulates β-catenin degradation

    Directory of Open Access Journals (Sweden)

    Chen Yuzhi

    2007-12-01

    Full Text Available Abstract Background The amyloid precursor protein (APP is genetically associated with Alzheimer's disease (AD. Elucidating the function of APP should help understand AD pathogenesis and provide insights into therapeutic designs against this devastating neurodegenerative disease. Results We demonstrate that APP expression in primary neurons induces β-catenin phosphorylation at Ser33, Ser37, and Thr41 (S33/37/T41 residues, which is a prerequisite for β-catenin ubiquitinylation and proteasomal degradation. APP-induced phosphorylation of β-catenin resulted in the reduction of total β-catenin levels, suggesting that APP expression promotes β-catenin degradation. In contrast, treatment of neurons with APP siRNAs increased total β-catenin levels and decreased β-catenin phosphorylation at residues S33/37/T41. Further, β-catenin was dramatically increased in hippocampal CA1 pyramidal cells from APP knockout animals. Acute expression of wild type APP or of familial AD APP mutants in primary neurons downregulated β-catenin in membrane and cytosolic fractions, and did not appear to affect nuclear β-catenin or β-catenin-dependent transcription. Conversely, in APP knockout CA1 pyramidal cells, accumulation of β-catenin was associated with the upregulation of cyclin D1, a downstream target of β-catenin signaling. Together, these data establish that APP downregulates β-catenin and suggest a role for APP in sustaining neuronal function by preventing cell cycle reactivation and maintaining synaptic integrity. Conclusion We have provided strong evidence that APP modulates β-catenin degradation in vitro and in vivo. Future studies may investigate whether APP processing is necessary for β-catenin downregulation, and determine if excessive APP expression contributes to AD pathogenesis through abnormal β-catenin downregulation.

  12. Manipulations of Amyloid Precursor Protein Cleavage Disrupt the Circadian Clock in Aging Drosophila

    OpenAIRE

    Blake, Matthew R.; Holbrook, Scott D.; Kotwica-Rolinska, Joanna; Chow, Eileen; Kretzschmar, Doris; Giebultowicz, Jadwiga M.

    2015-01-01

    Alzheimer’s disease (AD) is a neurodegenerative disease characterized by severe cognitive deterioration. While causes of AD pathology are debated, a large body of evidence suggests that increased cleavage of Amyloid Precursor Protein (APP) producing the neurotoxic Amyloid-β (Aβ) peptide plays a fundamental role in AD pathogenesis. One of the detrimental behavioral symptoms commonly associated with AD is the fragmentation of sleep-activity cycles with increased nighttime activity and daytime n...

  13. Copper binding to the Alzheimer’s disease amyloid precursor protein

    OpenAIRE

    Kong, Geoffrey K.-W.; Miles, Luke A.; Crespi, Gabriela A. N.; Morton, Craig J.; Ng, Hooi Ling; Barnham, Kevin J.; McKinstry, William J.; Cappai, Roberto; Michael W. Parker

    2007-01-01

    Alzheimer’s disease is the fourth biggest killer in developed countries. Amyloid precursor protein (APP) plays a central role in the development of the disease, through the generation of a peptide called Aβ by proteolysis of the precursor protein. APP can function as a metalloprotein and modulate copper transport via its extracellular copper binding domain (CuBD). Copper binding to this domain has been shown to reduce Aβ levels and hence a molecular understanding of the interaction between me...

  14. Schisandrin B protects PC12 cells by decreasing the expression of amyloid precursor protein and vacuolar protein sorting 35

    Institute of Scientific and Technical Information of China (English)

    Mingmin Yan; Shanping Mao; Huimin Dong; Baohui Liu; Qian Zhang; Gaofeng Pan; Zhiping Fu

    2012-01-01

    PC12 cell injury was induced using 20 μM amyloid β-protein 25-35 to establish a model of Alzheimer's disease.The cells were then treated with 5, 10, and 25 μM Schisandrin B.Methylthiazolyldiphenyl-tetrazolium bromide assays and Hoechst 33342 staining results showed that with increasing Schisandrin B concentration, the survival rate of PC12 cells injured by amyloid β-protein 25-35 gradually increased and the rate of apoptosis gradually decreased.Reverse transcription-PCR, immunocytochemical staining and western blot results showed that with increasing Schisandrin B concentration, the mRNA and protein expression of vacuolar protein sorting 35 and amyloid precursor protein were gradually decreased.Vacuolar protein sorting 35 and amyloid precursor protein showed a consistent trend for change.These findings suggest that 5, 10, and 25 μM Schisandrin B antagonizes the cellular injury induced by amyloid β-protein 25-35 in a dose-dependent manner.This may be caused by decreasing the expression of vacuolar protein sorting 35 and amyloid precursor protein.PC12 cell injury was induced using 20 μM amyloid β-protein 25-35 to establish a model of Alzheimer's disease.The cells were then treated with 5, 10, and 25 μM Schisandrin B.Methylthiazolyldiphenyl-tetrazolium bromide assays and Hoechst 33342 staining results showed that with increasing Schisandrin B concentration, the survival rate of PC12 cells injured by amyloid β-protein 25-35 gradually increased and the rate of apoptosis gradually decreased.Reverse transcription-PCR, immunocytochemical staining and western blot results showed that with increasing Schisandrin B concentration, the mRNA and protein expression of vacuolar protein sorting 35 and amyloid precursor protein were gradually decreased.Vacuolar protein sorting 35 and amyloid precursor protein showed a consistent trend for change.These findings suggest that 5, 10, and 25 μM Schisandrin B antagonizes the cellular injury induced by amyloid β-protein 25

  15. Exons 16 and 17 of the amyloid precursor protein gene in familial inclusion body myopathy.

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    Sivakumar, K; Cervenáková, L; Dalakas, M C; Leon-Monzon, M; Isaacson, S H; Nagle, J W; Vasconcelos, O; Goldfarb, L G

    1995-08-01

    Accumulation of beta-amyloid protein (A beta) occurs in some muscle fibers of patients with inclusion body myopathy and resembles the type of amyloid deposits seen in the affected tissues of patients with Alzheimer's disease and cerebrovascular amyloidosis. Because mutations in exons 16 and 17 of the beta-amyloid precursor protein (beta APP) gene on chromosome 21 have been identified in patients with early-onset familial Alzheimer's disease and Dutch-type cerebrovascular amyloidosis, we searched for mutations of the same region in patients with familial inclusion body myopathy. Sequencing of both alleles in 8 patients from four unrelated families did not reveal any mutations in these exons. The amyloid deposition in familial forms of inclusion body myopathy may be either due to errors in other gene loci, or it is secondary reflecting altered beta APP metabolism or myocyte degeneration and cell membrane degradation.

  16. Schisandrin B protects PC12 cells by decreasing the expression of amyloid precursor protein and vacuolar protein sorting 35.

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    Yan, Mingmin; Mao, Shanping; Dong, Huimin; Liu, Baohui; Zhang, Qian; Pan, Gaofeng; Fu, Zhiping

    2012-03-25

    PC12 cell injury was induced using 20 μM amyloid β-protein 25-35 to establish a model of Alzheimer's disease. The cells were then treated with 5, 10, and 25 μM Schisandrin B. Methylthiazolyldiphenyl-tetrazolium bromide assays and Hoechst 33342 staining results showed that with increasing Schisandrin B concentration, the survival rate of PC12 cells injured by amyloid β-protein 25-35 gradually increased and the rate of apoptosis gradually decreased. Reverse transcription-PCR, immunocytochemical staining and western blot results showed that with increasing Schisandrin B concentration, the mRNA and protein expression of vacuolar protein sorting 35 and amyloid precursor protein were gradually decreased. Vacuolar protein sorting 35 and amyloid precursor protein showed a consistent trend for change. These findings suggest that 5, 10, and 25 μM Schisandrin B antagonizes the cellular injury induced by amyloid β-protein 25-35 in a dose-dependent manner. This may be caused by decreasing the expression of vacuolar protein sorting 35 and amyloid precursor protein.

  17. Novel effects of FCCP [carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone] on amyloid precursor protein processing.

    Science.gov (United States)

    Connop, B P; Thies, R L; Beyreuther, K; Ida, N; Reiner, P B

    1999-04-01

    Amyloidogenic processing of the beta-amyloid precursor protein (APP) has been implicated in the pathology of Alzheimer's disease. Because it has been suggested that catabolic processing of the APP holoprotein occurs in acidic intracellular compartments, we studied the effects of the protonophore carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP) and the H+-ATPase inhibitor bafilomycin A1 on APP catabolism in human embryonic kidney 293 cells expressing either wild-type or "Swedish" mutant APP. Unlike bafilomycin A1, which inhibits beta-amyloid production in cells expressing mutant but not wild-type APP, FCCP inhibited beta-amyloid production in both cell types. Moreover, the effects of FCCP were independent of alterations in total cellular APP levels or APP maturation, and the concentrations used did not alter either cellular ATP levels or cell viability. Bafilomycin A1, which had no effect on beta-amyloid production in wild-type cells, inhibited endocytosis of fluorescent transferrin, whereas concentrations of FCCP that inhibited beta-amyloid production in these cells had no effect on endosomal function. Thus, in wild-type-expressing cells it appears that the beta-amyloid peptide is not produced in the classically defined endosome. Although bafilomycin A1 decreased beta-amyloid release from cells expressing mutant APP but not wild-type APP, it altered lysosomal function in both cell types, suggesting that in normal cells beta-amyloid is not produced in the lysosome. Although inhibition of beta-amyloid production by bafilomycin A1 in mutant cells may occur via changes in endosomal/lysosomal pH, our data suggest that FCCP inhibits wild-type beta-amyloid production by acting on a bafilomycin A1-insensitive acidic compartment that is distinct from either the endosome or the lysosome.

  18. Beta-secretase-cleaved amyloid precursor protein in Alzheimer brain: a morphologic study

    DEFF Research Database (Denmark)

    Sennvik, Kristina; Bogdanovic, N; Volkmann, Inga

    2004-01-01

    beta-amyloid (Abeta) is the main constituent of senile plaques seen in Alzheimer's disease. Abeta is derived from the amyloid precursor protein (APP) via proteolytic cleavage by proteases beta- and gamma-secretase. In this study, we examined content and localization of beta-secretase-cleaved APP...... the beta-sAPP immunostaining to be stronger and more extensive in gray matter in Alzheimer disease (AD) cases than controls. The axonal beta-sAPP staining was patchy and unevenly distributed for the AD cases, indicating impaired axonal transport. beta-sAPP was also found surrounding senile plaques...

  19. Specific Inhibition of β-Secretase Processing of the Alzheimer Disease Amyloid Precursor Protein.

    Science.gov (United States)

    Ben Halima, Saoussen; Mishra, Sabyashachi; Raja, K Muruga Poopathi; Willem, Michael; Baici, Antonio; Simons, Kai; Brüstle, Oliver; Koch, Philipp; Haass, Christian; Caflisch, Amedeo; Rajendran, Lawrence

    2016-03-08

    Development of disease-modifying therapeutics is urgently needed for treating Alzheimer disease (AD). AD is characterized by toxic β-amyloid (Aβ) peptides produced by β- and γ-secretase-mediated cleavage of the amyloid precursor protein (APP). β-secretase inhibitors reduce Aβ levels, but mechanism-based side effects arise because they also inhibit β-cleavage of non-amyloid substrates like Neuregulin. We report that β-secretase has a higher affinity for Neuregulin than it does for APP. Kinetic studies demonstrate that the affinities and catalytic efficiencies of β-secretase are higher toward non-amyloid substrates than toward APP. We show that non-amyloid substrates are processed by β-secretase in an endocytosis-independent manner. Exploiting this compartmentalization of substrates, we specifically target the endosomal β-secretase by an endosomally targeted β-secretase inhibitor, which blocked cleavage of APP but not non-amyloid substrates in many cell systems, including induced pluripotent stem cell (iPSC)-derived neurons. β-secretase inhibitors can be designed to specifically inhibit the Alzheimer process, enhancing their potential as AD therapeutics without undesired side effects.

  20. Cerebrolysin decreases amyloid-beta production by regulating amyloid protein precursor maturation in a transgenic model of Alzheimer's disease.

    Science.gov (United States)

    Rockenstein, Edward; Torrance, Magdalena; Mante, Michael; Adame, Anthony; Paulino, Amy; Rose, John B; Crews, Leslie; Moessler, Herbert; Masliah, Eliezer

    2006-05-15

    Cerebrolysin is a peptide mixture with neurotrophic effects that might reduce the neurodegenerative pathology in Alzheimer's disease (AD). We have previously shown in an amyloid protein precursor (APP) transgenic (tg) mouse model of AD-like neuropathology that Cerebrolysin ameliorates behavioral deficits, is neuroprotective, and decreases amyloid burden; however, the mechanisms involved are not completely clear. Cerebrolysin might reduce amyloid deposition by regulating amyloid-beta (Abeta) degradation or by modulating APP expression, maturation, or processing. To investigate these possibilities, APP tg mice were treated for 6 months with Cerebrolysin and analyzed in the water maze, followed by RNA, immunoblot, and confocal microscopy analysis of full-length (FL) APP and its fragments, beta-secretase (BACE1), and Abeta-degrading enzymes [neprilysin (Nep) and insulin-degrading enzyme (IDE)]. Consistent with previous studies, Cerebrolysin ameliorated the performance deficits in the spatial learning portion of the water maze and reduced the synaptic pathology and amyloid burden in the brains of APP tg mice. These effects were associated with reduced levels of FL APP and APP C-terminal fragments, but levels of BACE1, Notch1, Nep, and IDE were unchanged. In contrast, levels of active cyclin-dependent kinase-5 (CDK5) and glycogen synthase kinase-3beta [GSK-3beta; but not stress-activated protein kinase-1 (SAPK1)], kinases that phosphorylate APP, were reduced. Furthermore, Cerebrolysin reduced the levels of phosphorylated APP and the accumulation of APP in the neuritic processes. Taken together, these results suggest that Cerebrolysin might reduce AD-like pathology in the APP tg mice by regulating APP maturation and transport to sites where Abeta protein is generated. This study clarifies the mechanisms through which Cerebrolysin might reduce Abeta production and deposition in AD and further supports the importance of this compound in the potential treatment of early AD.

  1. Insights into the physiological function of the β-amyloid precursor protein: beyond Alzheimer's disease.

    Science.gov (United States)

    Dawkins, Edgar; Small, David H

    2014-06-01

    The β-amyloid precursor protein (APP) has been extensively studied for its role as the precursor of the β-amyloid protein (Aβ) of Alzheimer's disease. However, the normal function of APP remains largely unknown. This article reviews studies on the structure, expression and post-translational processing of APP, as well as studies on the effects of APP in vitro and in vivo. We conclude that the published data provide strong evidence that APP has a trophic function. APP is likely to be involved in neural stem cell development, neuronal survival, neurite outgrowth and neurorepair. However, the mechanisms by which APP exerts its actions remain to be elucidated. The available evidence suggests that APP interacts both intracellularly and extracellularly to regulate various signal transduction mechanisms. This article reviews studies on the structure, expression and post-translational processing of β-amyloid precursor protein (APP), as well as studies on the effects of APP in vitro and in vivo. We conclude that the published data provide strong evidence that APP has a trophic function. APP is likely to be involved in neural stem cell development, neuronal survival, neurite outgrowth and neurorepair. However, the mechanisms by which APP exerts its actions remain to be elucidated. The available evidence suggests that APP interacts both intracellularly and extracellularly to regulate various signal transduction mechanisms.

  2. Cellular prion protein expression is not regulated by the Alzheimer's amyloid precursor protein intracellular domain.

    Directory of Open Access Journals (Sweden)

    Victoria Lewis

    Full Text Available There is increasing evidence of molecular and cellular links between Alzheimer's disease (AD and prion diseases. The cellular prion protein, PrP(C, modulates the post-translational processing of the AD amyloid precursor protein (APP, through its inhibition of the β-secretase BACE1, and oligomers of amyloid-β bind to PrP(C which may mediate amyloid-β neurotoxicity. In addition, the APP intracellular domain (AICD, which acts as a transcriptional regulator, has been reported to control the expression of PrP(C. Through the use of transgenic mice, cell culture models and manipulation of APP expression and processing, this study aimed to clarify the role of AICD in regulating PrP(C. Over-expression of the three major isoforms of human APP (APP(695, APP(751 and APP(770 in cultured neuronal and non-neuronal cells had no effect on the level of endogenous PrP(C. Furthermore, analysis of brain tissue from transgenic mice over-expressing either wild type or familial AD associated mutant human APP revealed unaltered PrP(C levels. Knockdown of endogenous APP expression in cells by siRNA or inhibition of γ-secretase activity also had no effect on PrP(C levels. Overall, we did not detect any significant difference in the expression of PrP(C in any of the cell or animal-based paradigms considered, indicating that the control of cellular PrP(C levels by AICD is not as straightforward as previously suggested.

  3. Presentation of amyloidosis in carriers of the codon 692 mutation in the amyloid precursor protein gene (APP692)

    NARCIS (Netherlands)

    F. Forey; H.L.J. Tanghe (Hervé); M.F. Niermeijer (Martinus); C.M. van Duijn (Cock); J.C. van Swieten (John); F. van Harskamp (Frans); I. de Koning (Inge); M. Cruts (Marc); C. de Jonghe (Chris); S. Kumar-Singh (Samir); A. Tibben (Arend); C. van Broeckhoven (Christine); A. Hofman (Albert)

    2000-01-01

    textabstractSeveral mutations in the amyloid precursor protein (APP) gene may lead to either Alzheimer's disease or cerebral haemorrhage due to congophilic amyloid angiopathy (CAA). A single family is known in which both types of pathology are expressed because of a missense mutati

  4. Sorting by the cytoplasmic domain of the amyloid precursor protein binding receptor SorLA

    DEFF Research Database (Denmark)

    Nielsen, Morten S; Gustafsen, Camilla; Madsen, Peder

    2007-01-01

    -formation with the amyloid precursor protein it downregulates generation of Alzheimer's disease-associated Abeta-peptide. The receptor is mainly located in vesicles, suggesting a function in protein sorting and transport. Here we examined SorLA's trafficking using full-length and chimeric receptors and find that its...... established that the AP-1 adaptor complex is essential to SorLA's transport between Golgi membranes and endosomes. Our results further implicate the GGA proteins in SorLA trafficking and provide evidence that SNX1 and Vps35, as parts of the retromer complex or possibly in a separate context, are engaged...

  5. Structure and Synaptic Function of Metal Binding to the Amyloid Precursor Protein and its Proteolytic Fragments

    Science.gov (United States)

    Wild, Klemens; August, Alexander; Pietrzik, Claus U.; Kins, Stefan

    2017-01-01

    Alzheimer’s disease (AD) is ultimately linked to the amyloid precursor protein (APP). However, current research reveals an important synaptic function of APP and APP-like proteins (APLP1 and 2). In this context various neurotrophic and neuroprotective functions have been reported for the APP proteolytic fragments sAPPα, sAPPβ and the monomeric amyloid-beta peptide (Aβ). APP is a metalloprotein and binds copper and zinc ions. Synaptic activity correlates with a release of these ions into the synaptic cleft and dysregulation of their homeostasis is linked to different neurodegenerative diseases. Metal binding to APP or its fragments affects its structure and its proteolytic cleavage and therefore its physiological function at the synapse. Here, we summarize the current data supporting this hypothesis and provide a model of how these different mechanisms might be intertwined with each other. PMID:28197076

  6. Brain Endothelial Cells Produce Amyloid β from Amyloid Precursor Protein 770 and Preferentially Secrete the O-Glycosylated Form*

    Science.gov (United States)

    Kitazume, Shinobu; Tachida, Yuriko; Kato, Masaki; Yamaguchi, Yoshiki; Honda, Takashi; Hashimoto, Yasuhiro; Wada, Yoshinao; Saito, Takashi; Iwata, Nobuhisa; Saido, Takaomi; Taniguchi, Naoyuki

    2010-01-01

    Deposition of amyloid β (Aβ) in the brain is closely associated with Alzheimer disease (AD). Aβ is generated from amyloid precursor protein (APP) by the actions of β- and γ-secretases. In addition to Aβ deposition in the brain parenchyma, deposition of Aβ in cerebral vessel walls, termed cerebral amyloid angiopathy, is observed in more than 80% of AD individuals. The mechanism for how Aβ accumulates in blood vessels remains largely unknown. In the present study, we show that brain endothelial cells expressed APP770, a differently spliced APP mRNA isoform from neuronal APP695, and produced Aβ40 and Aβ42. Furthermore, we found that the endothelial APP770 had sialylated core 1 type O-glycans. Interestingly, Ο-glycosylated APP770 was preferentially processed by both α- and β-cleavage and secreted into the media, suggesting that O-glycosylation and APP processing involved related pathways. By immunostaining human brain sections with an anti-APP770 antibody, we found that APP770 was expressed in vascular endothelial cells. Because we were able to detect O-glycosylated sAPP770β in human cerebrospinal fluid, this unique soluble APP770β has the potential to serve as a marker for cortical dementias such as AD and vascular dementia. PMID:20952385

  7. Cannabidiol promotes amyloid precursor protein ubiquitination and reduction of beta amyloid expression in SHSY5YAPP+ cells through PPARγ involvement.

    Science.gov (United States)

    Scuderi, Caterina; Steardo, Luca; Esposito, Giuseppe

    2014-07-01

    The amyloidogenic cascade is regarded as a key factor at the basis of Alzheimer's disease (AD) pathogenesis. The aberrant cleavage of amyloid precursor protein (APP) induces an increased production and a subsequent aggregation of beta amyloid (Aβ) peptide in limbic and association cortices. As a result, altered neuronal homeostasis and oxidative injury provoke tangle formation with consequent neuronal loss. Cannabidiol (CBD), a Cannabis derivative devoid of psychotropic effects, has attracted much attention because it may beneficially interfere with several Aβ-triggered neurodegenerative pathways, even though the mechanism responsible for such actions remains unknown. In the present research, the role of CBD was investigated as a possible modulating compound of APP processing in SHSY5Y(APP+) neurons. In addition, the putative involvement of peroxisome proliferator-activated receptor-γ (PPARγ) was explored as a candidate molecular site responsible for CBD actions. Results indicated the CBD capability to induce the ubiquitination of APP protein which led to a substantial decrease in APP full length protein levels in SHSY5Y(APP+) with the consequent decrease in Aβ production. Moreover, CBD promoted an increased survival of SHSY5Y(APP+) neurons, by reducing their long-term apoptotic rate. Obtained results also showed that all, here observed, CBD effects were dependent on the selective activation of PPARγ.

  8. β-Amyloid precursor protein: function in stem cell development and Alzheimer's disease brain.

    Science.gov (United States)

    Small, David H; Hu, Yanling; Bolós, Marta; Dawkins, Edgar; Foa, Lisa; Young, Kaylene M

    2014-01-01

    Stem cell therapy may be a suitable approach for the treatment of many neurodegenerative diseases. However, one major impediment to the development of successful cell-based therapies is our limited understanding of the mechanisms that instruct neural stem cell behaviour, such as proliferation and cell fate specification. The β-amyloid precursor protein (APP) of Alzheimer's disease (AD) may play an important role in neural stem cell proliferation and differentiation. Our recent work shows that in vitro, APP stimulates neural stem or progenitor cell proliferation and neuronal differentiation. The effect on proliferation is mediated by an autocrine factor that we have identified as cystatin C. As cystatin C expression is also reported to inhibit the development of amyloid pathology in APP transgenic mice, our finding has implications for the possible use of cystatin C for the therapy of AD.

  9. The intact Kunitz domain protects the amyloid precursor protein from being processed by matriptase-2.

    Science.gov (United States)

    Beckmann, Anna-Madeleine; Glebov, Konstantin; Walter, Jochen; Merkel, Olaf; Mangold, Martin; Schmidt, Frederike; Becker-Pauly, Christoph; Gütschow, Michael; Stirnberg, Marit

    2016-08-01

    Proteolytic processing of the amyloid precursor protein (APP) leads to amyloid-β (Aβ) peptides. So far, the mechanism of APP processing is insufficiently characterized at the molecular level. Whereas the knowledge of Aβ generation by several proteases has been expanded, the contribution of the Kunitz-type protease inhibitor domain (KPI) present in two major APP isoforms to the complex proteolytic processing of APP is poorly understood. In this study, we have identified KPI-containing APP as a very potent, slow-binding inhibitor for the membrane-bound proteolytic regulator of iron homeostasis matriptase-2 by forming stable complexes with its target protease in HEK cells. Inhibition and complex formation depend on the intact KPI domain. By inhibiting matriptase-2, KPI-containing APP is protected from matriptase-2-mediated proteolysis within the Aβ region, thus preventing the generation of N-terminally truncated Aβ.

  10. The role of the E2 copper binding domain in the cell biology of the amyloid precursor protein

    OpenAIRE

    Blanthorn-Hazell, Sophee

    2015-01-01

    Alzheimer’s disease is a neurodegenerative disorder characterised by the accumulation, in the brain, of neurotoxic amyloid beta-(Aβ) peptides. These peptides are generated from the amyloid precursor protein (APP) via the amyloidogenic proteolytic pathway which also leads to the formation of soluble APP beta (sAPPβ). Alternatively, APP can be cleaved by the non-amyloidogenic pathway in which an α-secretase activity cleaves the protein within the Aβ region generating soluble APP alpha (sAPPα). ...

  11. Amyloid precursor protein (APP) affects global protein synthesis in dividing human cells.

    Science.gov (United States)

    Sobol, Anna; Galluzzo, Paola; Liang, Shuang; Rambo, Brittany; Skucha, Sylvia; Weber, Megan J; Alani, Sara; Bocchetta, Maurizio

    2015-05-01

    Hypoxic non-small cell lung cancer (NSCLC) is dependent on Notch-1 signaling for survival. Targeting Notch-1 by means of γ-secretase inhibitors (GSI) proved effective in killing hypoxic NSCLC. Post-mortem analysis of GSI-treated, NSCLC-burdened mice suggested enhanced phosphorylation of 4E-BP1 at threonines 37/46 in hypoxic tumor tissues. In vitro dissection of this phenomenon revealed that Amyloid Precursor Protein (APP) inhibition was responsible for a non-canonical 4E-BP1 phosphorylation pattern rearrangement-a process, in part, mediated by APP regulation of the pseudophosphatase Styx. Upon APP depletion we observed modifications of eIF-4F composition indicating increased recruitment of eIF-4A to the mRNA cap. This phenomenon was supported by the observation that cells with depleted APP were partially resistant to silvestrol, an antibiotic that interferes with eIF-4A assembly into eIF-4F complexes. APP downregulation in dividing human cells increased the rate of global protein synthesis, both cap- and IRES-dependent. Such an increase seemed independent of mTOR inhibition. After administration of Torin-1, APP downregulation and Mechanistic Target of Rapamycin Complex 1 (mTORC-1) inhibition affected 4E-BP1 phosphorylation and global protein synthesis in opposite fashions. Additional investigations indicated that APP operates independently of mTORC-1. Key phenomena described in this study were reversed by overexpression of the APP C-terminal domain. The presented data suggest that APP may be a novel regulator of protein synthesis in dividing human cells, both cancerous and primary. Furthermore, APP appears to affect translation initiation using mechanisms seemingly dissimilar to mTORC-1 regulation of cap-dependent protein synthesis.

  12. Inhibition of beta-site amyloid precursor protein-cleaving enzyme and beta-amyloid precursor protein genes in SK-N-SH cells

    Institute of Scientific and Technical Information of China (English)

    Suqin Gao; Lin Sun; Enji Han; Hongshun Qi; Jinbo Feng; Shunliang Xu; Wen Xia

    2009-01-01

    BACKGROUND:Previous studies have demonstrated that Piper futokadsura stem selectively inhibits expression of amyloid precursor protein (APP) at the mRNA level.In addition,the piperlonguminine (A) and dihydropiperlonguminine (B) components (1:0.8),which can be separated from Futokadsura stem,selectively inhibit expression of the APP at mRNA and protein levels.OBJECTIVE:Based on previous findings,the present study investigated the effects of β-site amyloid precursor protein cleaving enzyme (BACE1) and APP genes on the production of β-amyloid peptide 42 (Aβ42) in human neuroblastoma cells (SK-N-SH cells) using small interfering RNAs (siRNAs) and A/B components separated from Futokadsura stem,respectively.DESIGN,TIME AND SETTING:A gene interference-based randomized,controlled,in vitro experiment was performed at the Key Laboratory of Cardiovascular Remodeling and Function Research,Ministries of Education and Public Health,and Institute of Pharmacologic Research,School of Pharmaceutical Science & Department of Biochemistry,School of Medicine,Shandong University between July 2006 and December 2007.MATERIALS:SK-N-SH cells were provided by Shanghai Institutes of Biological Sciences,Chinese Academy of Sciences,Shanghai,China;mouse anti-human BACE1 monoclonal antibody was purchased from R&D Systems,USA;mouse anti-human APP monoclonal antibody was purchased from Cell Signaling Technology,USA;and horseradish peroxidase (HRP)-conjugated goat anti-mouse IgG was provided by Sigma,USA.METHODS:The human BACE1 cDNA sequence was obtained from NCBI website (www.ncbi.nlm.nih.gov/sites/entrez).Three pairs of siRNAs,specific to human BACE1 gene,were synthesized through the use of Silencer? pre-designed siRNA specification,and were transfected into SK-N-SH cells with siPORT NeoFX transfection agent to compare the effects of different concentrations of siRNAs (10-50 nmol/L) on SK-N-SH cells.Futokadsura stem was separated and purified with chemical methods,and the crystal was composed of

  13. FKBP12 regulates the localization and processing of amyloid precursor protein in human cell lines

    Indian Academy of Sciences (India)

    Fan-Lun Liu; Ting-Yi Liu; Fan-Lu Kung

    2014-03-01

    One of the pathological hallmarks of Alzheimer’s disease is the presence of insoluble extracellular amyloid plaques. These plaques are mainly constituted of amyloid beta peptide (A), a proteolytic product of amyloid precursor protein (APP). APP processing also generates the APP intracellular domain (AICD). We have previously demonstrated that AICD interacts with FKBP12, a peptidyl-prolyl cis-trans isomerase (PPIase) ubiquitous in nerve systems. This interaction was interfered by FK506, a clinically used immunosuppressant that has recently been reported to be neuroprotective. To elucidate the roles of FKBP12 in the pathogenesis of Alzheimer’s disease, the effect of FKBP12 overexpression on APP processing was evaluated. Our results revealed that APP processing was shifted towards the amyloidogenic pathway, accompanied by a change in the subcellular localization of APP, upon FKBP12 overexpression. This FKBP12-overexpression-induced effect was reverted by FK506. These findings support our hypothesis that FKBP12 may participate in the regulation of APP processing. FKBP12 overexpression may lead to the stabilization of a certain isomer (presumably the cis form) of the Thr668-Pro669 peptide bond in AICD, therefore change its affinity to flotillin-1 or other raft-associated proteins, and eventually change the localization pattern and cause a shift in the proteolytic processing of APP.

  14. Consequences of Inhibiting Amyloid Precursor Protein Processing Enzymes on Synaptic Function and Plasticity

    Directory of Open Access Journals (Sweden)

    Hui Wang

    2012-01-01

    Full Text Available Alzheimer's disease (AD is a neurodegenerative disease, one of whose major pathological hallmarks is the accumulation of amyloid plaques comprised of aggregated β-amyloid (Aβ peptides. It is now recognized that soluble Aβ oligomers may lead to synaptic dysfunctions early in AD pathology preceding plaque deposition. Aβ is produced by a sequential cleavage of amyloid precursor protein (APP by the activity of β- and γ-secretases, which have been identified as major candidate therapeutic targets of AD. This paper focuses on how Aβ alters synaptic function and the functional consequences of inhibiting the activity of the two secretases responsible for Aβ generation. Abnormalities in synaptic function resulting from the absence or inhibition of the Aβ-producing enzymes suggest that Aβ itself may have normal physiological functions which are disrupted by abnormal accumulation of Aβ during AD pathology. This interpretation suggests that AD therapeutics targeting the β- and γ-secretases should be developed to restore normal levels of Aβ or combined with measures to circumvent the associated synaptic dysfunction(s in order to have minimal impact on normal synaptic function.

  15. Selective translational control of the Alzheimer amyloid precursor protein transcript by iron regulatory protein-1.

    Science.gov (United States)

    Cho, Hyun-Hee; Cahill, Catherine M; Vanderburg, Charles R; Scherzer, Clemens R; Wang, Bin; Huang, Xudong; Rogers, Jack T

    2010-10-08

    Iron influx increases the translation of the Alzheimer amyloid precursor protein (APP) via an iron-responsive element (IRE) RNA stem loop in its 5'-untranslated region. Equal modulated interaction of the iron regulatory proteins (IRP1 and IRP2) with canonical IREs controls iron-dependent translation of the ferritin subunits. However, our immunoprecipitation RT-PCR and RNA binding experiments demonstrated that IRP1, but not IRP2, selectively bound the APP IRE in human neural cells. This selective IRP1 interaction pattern was evident in human brain and blood tissue from normal and Alzheimer disease patients. We computer-predicted an optimal novel RNA stem loop structure for the human, rhesus monkey, and mouse APP IREs with reference to the canonical ferritin IREs but also the IREs encoded by erythroid heme biosynthetic aminolevulinate synthase and Hif-2α mRNAs, which preferentially bind IRP1. Selective 2'-hydroxyl acylation analyzed by primer extension analysis was consistent with a 13-base single-stranded terminal loop and a conserved GC-rich stem. Biotinylated RNA probes deleted of the conserved CAGA motif in the terminal loop did not bind to IRP1 relative to wild type probes and could no longer base pair to form a predicted AGA triloop. An AGU pseudo-triloop is key for IRP1 binding to the canonical ferritin IREs. RNA probes encoding the APP IRE stem loop exhibited the same high affinity binding to rhIRP1 as occurs for the H-ferritin IRE (35 pm). Intracellular iron chelation increased binding of IRP1 to the APP IRE, decreasing intracellular APP expression in SH-SY5Y cells. Functionally, shRNA knockdown of IRP1 caused increased expression of neural APP consistent with IRP1-APP IRE-driven translation.

  16. Yeast Two-Hybrid Screening for Proteins that Interact with the Extracellular Domain of Amyloid Precursor Protein.

    Science.gov (United States)

    Yu, You; Li, Yinan; Zhang, Yan

    2016-04-01

    Alzheimer's disease (AD) is a neurodegenerative disorder in which amyloid β plaques are a pathological characteristic. Little is known about the physiological functions of amyloid β precursor protein (APP). Based on its structure as a type I transmembrane protein, it has been proposed that APP might be a receptor, but so far, no ligand has been reported. In the present study, 9 proteins binding to the extracellular domain of APP were identified using a yeast two-hybrid system. After confirming the interactions in the mammalian system, mutated PLP1, members of the FLRT protein family, and KCTD16 were shown to interact with APP. These proteins have been reported to be involved in Pelizaeus-Merzbacher disease (PMD) and axon guidance. Therefore, our results shed light on the mechanisms of physiological function of APP in AD, PMD, and axon guidance.

  17. Estrogen stimulates release of secreted amyloid precursor protein from primary rat cortical neurons via protein kinase C pathway

    Institute of Scientific and Technical Information of China (English)

    Sun ZHANG; Ying HUANG; Yi-chun ZHU; Tai YAO

    2005-01-01

    Aim: To investigate the mechanism of the action of estrogen, which stimulates the release of secreted amyloid precursor protein α (sAPPα) and decreases the gen eration of amyloidprotein (Aβ), a dominant component in senile plaques in the brains of Alzheimer's disease patients. Methods: Experiments were carried out inprimary rat cortical neurons, and Western blot was used to detect sAPPα in aculture medium and the total amount of cellular amyloid precursor protein (APP) in neurons. Results: 17β-Estradiol (but not 17α-estradiol) and β-estradiol 6-(Ocarboxymethyl) oxime: BSA increased the secretion of sAPPα and this effect was blocked by protein kinase C (PKC) inhibitor calphostin C, but not by the classical estrogen receptor antagonist ICI 182,780. Meanwhile, 17β-estradiol did not alter the synthesis of cellular APP. Conclusion: The effect of 17β-estradiol on sAPPα secretion is likely mediated through the membrane binding sites, and needs molecular configuration specificity of the ligand. Furthermore, the action of the PKC dependent pathway might be involved in estrogen-induced sAPPα secretion.

  18. LINGO-1 promotes lysosomal degradation of amyloidprotein precursor.

    Science.gov (United States)

    de Laat, Rian; Meabon, James S; Wiley, Jesse C; Hudson, Mark P; Montine, Thomas J; Bothwell, Mark

    2015-01-01

    Sequential proteolytic cleavages of amyloidprotein precursor (AβPP) by β-secretase and γ-secretase generate amyloid β (Aβ) peptides, which are thought to contribute to Alzheimer's disease (AD). Much of this processing occurs in endosomes following endocytosis of AβPP from the plasma membrane. However, this pathogenic mode of processing AβPP may occur in competition with lysosomal degradation of AβPP, a common fate of membrane proteins trafficking through the endosomal system. Following up on published reports that LINGO-1 binds and promotes the amyloidogenic processing of AβPP we have examined the consequences of LINGO-1/AβPP interactions. We report that LINGO-1 and its paralogs, LINGO-2 and LINGO-3, decrease processing of AβPP in the amyloidogenic pathway by promoting lysosomal degradation of AβPP. We also report that LINGO-1 levels are reduced in AD brain, representing a possible pathogenic mechanism stimulating the generation of Aβ peptides in AD.

  19. LINGO-1 promotes lysosomal degradation of amyloidprotein precursor

    Directory of Open Access Journals (Sweden)

    Rian de Laat

    2015-03-01

    Full Text Available Sequential proteolytic cleavages of amyloidprotein precursor (AβPP by β-secretase and γ-secretase generate amyloid β (Aβ peptides, which are thought to contribute to Alzheimer's disease (AD. Much of this processing occurs in endosomes following endocytosis of AβPP from the plasma membrane. However, this pathogenic mode of processing AβPP may occur in competition with lysosomal degradation of AβPP, a common fate of membrane proteins trafficking through the endosomal system. Following up on published reports that LINGO-1 binds and promotes the amyloidogenic processing of AβPP we have examined the consequences of LINGO-1/AβPP interactions. We report that LINGO-1 and its paralogs, LINGO-2 and LINGO-3, decrease processing of AβPP in the amyloidogenic pathway by promoting lysosomal degradation of AβPP. We also report that LINGO-1 levels are reduced in AD brain, representing a possible pathogenic mechanism stimulating the generation of Aβ peptides in AD.

  20. The coding sequence of amyloid-beta precursor protein APP contains a neural-specific promoter element.

    NARCIS (Netherlands)

    Collin, R.W.J.; Martens, G.J.M.

    2006-01-01

    The amyloid-beta precursor protein APP is generally accepted to be involved in the pathology of Alzheimer's disease. Since its physiological role is still unclear, we decided to study the function of APP via stable transgenesis in the amphibian Xenopus laevis. However, the application of constructs

  1. A Synthetic Peptide with the Putative Iron Binding Motif of Amyloid Precursor Protein (APP) Does Not Catalytically Oxidize Iron

    NARCIS (Netherlands)

    Honarmand Ebrahimi, K.; Hagedoorn, P.L.; Hagen, W.R.

    2012-01-01

    The β-amyloid precursor protein (APP), which is a key player in Alzheimer's disease, was recently reported to possess an Fe(II) binding site within its E2 domain which exhibits ferroxidase activity [Duce et al. 2010, Cell 142: 857]. The putative ligands of this site were compared to those in the fer

  2. Lost region in amyloid precursor protein (APP) through TALEN-mediated genome editing alters mitochondrial morphology.

    Science.gov (United States)

    Wang, Yajie; Wu, Fengyi; Pan, Haining; Zheng, Wenzhong; Feng, Chi; Wang, Yunfu; Deng, Zixin; Wang, Lianrong; Luo, Jie; Chen, Shi

    2016-02-29

    Alzheimer's disease (AD) is characterized by amyloid-β (Aβ) deposition in the brain. Aβ plaques are produced through sequential β/γ cleavage of amyloid precursor protein (APP), of which there are three main APP isoforms: APP695, APP751 and APP770. KPI-APPs (APP751 and APP770) are known to be elevated in AD, but the reason remains unclear. Transcription activator-like (TAL) effector nucleases (TALENs) induce mutations with high efficiency at specific genomic loci, and it is thus possible to knock out specific regions using TALENs. In this study, we designed and expressed TALENs specific for the C-terminus of APP in HeLa cells, in which KPI-APPs are predominantly expressed. The KPI-APP mutants lack a 12-aa region that encompasses a 5-aa trans-membrane (TM) region and 7-aa juxta-membrane (JM) region. The mutated KPI-APPs exhibited decreased mitochondrial localization. In addition, mitochondrial morphology was altered, resulting in an increase in spherical mitochondria in the mutant cells through the disruption of the balance between fission and fusion. Mitochondrial dysfunction, including decreased ATP levels, disrupted mitochondrial membrane potential, increased ROS generation and impaired mitochondrial dehydrogenase activity, was also found. These results suggest that specific regions of KPI-APPs are important for mitochondrial localization and function.

  3. IFN-gamma promotes complement expression and attenuates amyloid plaque deposition in amyloid beta precursor protein transgenic mice.

    Science.gov (United States)

    Chakrabarty, Paramita; Ceballos-Diaz, Carolina; Beccard, Amanda; Janus, Christopher; Dickson, Dennis; Golde, Todd E; Das, Pritam

    2010-05-01

    Reactive gliosis surrounding amyloid beta (Abeta) plaques is an early feature of Alzheimer's disease pathogenesis and has been postulated to represent activation of the innate immune system in an apparently ineffective attempt to clear or neutralize Abeta aggregates. To evaluate the role of IFN-gamma-mediated neuroinflammation on the evolution of Abeta pathology in transgenic (Tg) mice, we have expressed murine IFN-gamma (mIFN-gamma) in the brains of Abeta precursor protein (APP) Tg mice using recombinant adeno-associated virus serotype 1. Expression of mIFN-gamma in brains of APP TgCRND8 mice results in robust noncell autonomous activation of microglia and astrocytes, and a concomitant significant suppression of Abeta deposition. In these mice, mIFN-gamma expression upregulated multiple glial activation markers, early components of the complement cascade as well as led to infiltration of Ly-6c positive peripheral monocytes but no significant effects on APP levels, APP processing or steady-state Abeta levels were noticed in vivo. Taken together, these results suggest that mIFN-gamma expression in the brain suppresses Abeta accumulation through synergistic effects of activated glia and components of the innate immune system that enhance Abeta aggregate phagocytosis.

  4. AChE and the amyloid precursor protein (APP) - Cross-talk in Alzheimer's disease.

    Science.gov (United States)

    Nalivaeva, Natalia N; Turner, Anthony J

    2016-11-25

    The amyloid precursor protein (APP) and acetylcholinesterase (AChE) are multi-faceted proteins with a wide range of vital functions, both crucially linked with the pathogenesis of Alzheimer's disease (AD). APP is the precursor of the Aβ peptide, the pathological agent in AD, while AChE is linked to its pathogenesis either by increasing cholinergic deficit or exacerbating Aβ fibril formation and toxicity. As such, both proteins are the main targets in AD therapeutics with AChE inhibitors being currently the only clinically available AD drugs. In our studies we have demonstrated an important inter-relation in functioning of these proteins. Both can be released from the cell membrane and we have shown that AChE shedding involves a metalloproteinase-mediated mechanism which, like the α-secretase dependent cleavage of APP, is stimulated by cholinergic agonists. Overexpression of the neuronal specific isoform APP695 in neuronal cells substantially decreased levels of the AChE mRNA, protein and catalytic activity accompanied by a similar decrease in mRNA levels of the AChE membrane anchor, PRiMA (proline rich membrane anchor). We further established that this regulation does not involve APP processing and its intracellular domain (AICD) but requires the E1 region of APP, specifically its copper-binding domain. On the contrary, siRNA knock-down of APP in cholinergic SN56 cells resulted in a significant upregulation of AChE mRNA levels. Hence APP may influence AChE physiology while released AChE may regulate amyloidogenesis through multiple mechanisms suggesting novel therapeutic targets.

  5. Amyloid precursor protein regulates migration and metalloproteinase gene expression in prostate cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, Toshiaki; Ikeda, Kazuhiro; Horie-Inoue, Kuniko [Division of Gene Regulation and Signal Transduction, Research Center for Genomic Medicine, Saitama Medical University, Saitama 350-1241 (Japan); Inoue, Satoshi, E-mail: INOUE-GER@h.u-tokyo.ac.jp [Division of Gene Regulation and Signal Transduction, Research Center for Genomic Medicine, Saitama Medical University, Saitama 350-1241 (Japan); Department of Geriatric Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655 (Japan); Department of Anti-Aging Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655 (Japan)

    2014-09-26

    Highlights: • APP knockdown reduced proliferation and migration of prostate cancer cells. • APP knockdown reduced expression of metalloproteinase and EMT-related genes. • APP overexpression promoted LNCaP cell migration. • APP overexpression increased expression of metalloproteinase and EMT-related genes. - Abstract: Amyloid precursor protein (APP) is a type I transmembrane protein, and one of its processed forms, β-amyloid, is considered to play a central role in the development of Alzheimer’s disease. We previously showed that APP is a primary androgen-responsive gene in prostate cancer and that its increased expression is correlated with poor prognosis for patients with prostate cancer. APP has also been implicated in several human malignancies. Nevertheless, the mechanism underlying the pro-proliferative effects of APP on cancers is still not well-understood. In the present study, we explored a pathophysiological role for APP in prostate cancer cells using siRNA targeting APP (siAPP). The proliferation and migration of LNCaP and DU145 prostate cancer cells were significantly suppressed by siAPP. Differentially expressed genes in siAPP-treated cells compared to control siRNA-treated cells were identified by microarray analysis. Notably, several metalloproteinase genes, such as ADAM10 and ADAM17, and epithelial–mesenchymal transition (EMT)-related genes, such as VIM, and SNAI2, were downregulated in siAPP-treated cells as compared to control cells. The expression of these genes was upregulated in LNCaP cells stably expressing APP when compared with control cells. APP-overexpressing LNCaP cells exhibited enhanced migration in comparison to control cells. These results suggest that APP may contribute to the proliferation and migration of prostate cancer cells by modulating the expression of metalloproteinase and EMT-related genes.

  6. Amyloidprecursor protein: Multiple fragments, numerous transport routes and mechanisms.

    Science.gov (United States)

    Muresan, Virgil; Ladescu Muresan, Zoia

    2015-05-15

    This review provides insight into the intraneuronal transport of the AmyloidPrecursor Protein (APP), the prototype of an extensively posttranslationally modified and proteolytically cleaved transmembrane protein. Uncovering the intricacies of APP transport proves to be a challenging endeavor of cell biology research, deserving increased priority, since APP is at the core of the pathogenic process in Alzheimer's disease. After being synthesized in the endoplasmic reticulum in the neuronal soma, APP enters the intracellular transport along the secretory, endocytic, and recycling routes. Along these routes, APP undergoes cleavage into defined sets of fragments, which themselves are transported - mostly independently - to distinct sites in neurons, where they exert their functions. We review the currently known routes and mechanisms of transport of full-length APP, and of APP fragments, commenting largely on the experimental challenges posed by studying transport of extensively cleaved proteins. The review emphasizes the interrelationships between the proteolytic and posttranslational modifications, the intracellular transport, and the functions of the APP species. A goal remaining to be addressed in the future is the incorporation of the various views on APP transport into a coherent picture. In this review, the disease context is only marginally addressed; the focus is on the basic biology of APP transport under normal conditions. As shown, the studies of APP transport uncovered numerous mechanisms of transport, some of them conventional, and others, novel, awaiting exploration.

  7. Inflammatory Eicosanoids Increase Amyloid Precursor Protein Expression via Activation of Multiple Neuronal Receptors.

    Science.gov (United States)

    Herbst-Robinson, Katie J; Liu, Li; James, Michael; Yao, Yuemang; Xie, Sharon X; Brunden, Kurt R

    2015-12-17

    Senile plaques comprised of Aβ peptides are a hallmark of Alzheimer's disease (AD) brain, as are activated glia that release inflammatory molecules, including eicosanoids. Previous studies have demonstrated that amyloid precursor protein (APP) and Aβ levels can be increased through activation of thromboxane A2-prostanoid (TP) receptors on neurons. We demonstrate that TP receptor regulation of APP expression depends on Gαq-signaling and conventional protein kinase C isoforms. Importantly, we discovered that Gαq-linked prostaglandin E2 and leukotriene D4 receptors also regulate APP expression. Prostaglandin E2 and thromboxane A2, as well as total APP levels, were found to be elevated in the brains of aged 5XFAD transgenic mice harboring Aβ plaques and activated glia, suggesting that increased APP expression resulted from eicosanoid binding to Gαq-linked neuronal receptors. Notably, inhibition of eicosanoid synthesis significantly lowered brain APP protein levels in aged 5XFAD mice. These results provide new insights into potential AD therapeutic strategies.

  8. Expression Characterization and Preparation of Human Amyloid Precursor Protein in Escherichia coli

    Institute of Scientific and Technical Information of China (English)

    XU Guang-wei; WANG Jia-peng; HUANG Xue-mei; ZHANG Ying-jiu

    2009-01-01

    To analyze whether expressed amyloid precursor protein(APP) existed in hydrophilic(cytoplasmid) or hy-drophobic(lipid bilayer) environment in E. coli and to obtain intact APP for study on its function, we investigated the expression characterization and preparation of the three intact isoforms APP770, APP751, and APP695 in E. coli. The results show that these expressed APPs existed both in hydrophilic cytoplasm region as inclusion bodies and hy-drophobic membrane region as membrane-bound state in E. coll. APPs in inclusion bodies were purified on an NTA-Ni2. agarose column after dissolving in the urea buffer and APPs in membrane-bound state were obtained by ultracentrifugation. The activity analysis indicates that APP770 and APP751 exhibited strong trypsin-inhibitory activity like the natural ones. These results indicate that E. coil cells can be used as host cells for the expression of human integral membrane protein like APP in either soluble or membrane-bound state unless the interest protein undergone post-translational modification is required.

  9. The Drosophila homologue of the amyloid precursor protein is a conserved modulator of Wnt PCP signaling.

    Directory of Open Access Journals (Sweden)

    Alessia Soldano

    Full Text Available Wnt Planar Cell Polarity (PCP signaling is a universal regulator of polarity in epithelial cells, but it regulates axon outgrowth in neurons, suggesting the existence of axonal modulators of Wnt-PCP activity. The Amyloid precursor proteins (APPs are intensely investigated because of their link to Alzheimer's disease (AD. APP's in vivo function in the brain and the mechanisms underlying it remain unclear and controversial. Drosophila possesses a single APP homologue called APP Like, or APPL. APPL is expressed in all neurons throughout development, but has no established function in neuronal development. We therefore investigated the role of Drosophila APPL during brain development. We find that APPL is involved in the development of the Mushroom Body αβ neurons and, in particular, is required cell-autonomously for the β-axons and non-cell autonomously for the α-axons growth. Moreover, we find that APPL is a modulator of the Wnt-PCP pathway required for axonal outgrowth, but not cell polarity. Molecularly, both human APP and fly APPL form complexes with PCP receptors, thus suggesting that APPs are part of the membrane protein complex upstream of PCP signaling. Moreover, we show that APPL regulates PCP pathway activation by modulating the phosphorylation of the Wnt adaptor protein Dishevelled (Dsh by Abelson kinase (Abl. Taken together our data suggest that APPL is the first example of a modulator of the Wnt-PCP pathway specifically required for axon outgrowth.

  10. Amyloid Precursor Proteins Are Dynamically Trafficked and Processed During Neuronal Development

    Directory of Open Access Journals (Sweden)

    Jenna M. Ramaker

    2016-11-01

    Full Text Available Proteolytic processing of the Amyloid Precursor Protein (APP produces beta-amyloid (Aβ peptide fragments that accumulate in Alzheimer’s Disease (AD, but APP may also regulate multiple aspects of neuronal development, albeit via mechanisms that are not well understood. APP is a member of a family of transmembrane glycoproteins expressed by all higher organisms, including two mammalian orthologs (APLP1 and APLP2 that have complicated investigations into the specific activities of APP. By comparison, insects express only a single APP-related protein (APP-Like, or APPL that contains the same protein interaction domains identified in APP. However, unlike its mammalian orthologs, APPL is only expressed by neurons, greatly simplifying an analysis of its functions in vivo. Like APP, APPL is processed by secretases to generate a similar array of extracellular and intracellular cleavage fragments, as well as an Aβ-like fragment that can induce neurotoxic responses in the brain. Exploiting the complementary advantages of two insect models (Drosophila melanogaster and Manduca sexta, we have investigated the regulation of APPL trafficking and processing with respect to different aspects of neuronal development. By comparing the behavior of endogenously expressed APPL with fluorescently tagged versions of APPL and APP, we have shown that some full-length protein is consistently trafficked into the most motile regions of developing neurons both in vitro and in vivo. Concurrently, much of the holoprotein is rapidly processed into N- and C-terminal fragments that undergo bi-directional transport within distinct vesicle populations. Unexpectedly, we also discovered that APPL can be transiently sequestered into an amphisome-like compartment in developing neurons, while manipulations targeting APPL cleavage altered their motile behavior in cultured embryos. These data suggest that multiple mechanisms restrict the bioavailability of the holoprotein to regulate

  11. Synaptotrophic effects of human amyloid beta protein precursors in the cortex of transgenic mice.

    Science.gov (United States)

    Mucke, L; Masliah, E; Johnson, W B; Ruppe, M D; Alford, M; Rockenstein, E M; Forss-Petter, S; Pietropaolo, M; Mallory, M; Abraham, C R

    1994-12-15

    The amyloid precursor protein (APP) is involved in Alzheimer's disease (AD) because its degradation products accumulate abnormally in AD brains and APP mutations are associated with early onset AD. However, its role in health and disease appears to be complex, with different APP derivatives showing either neurotoxic or neurotrophic effects in vitro. To elucidate the effects APP has on the brain in vivo, cDNAs encoding different forms of human APP (hAPP) were placed downstream of the neuron-specific enolase (NSE) promoter. In multiple lines of NSE-hAPP transgenic mice neuronal overexpression of hAPP was accompanied by an increase in the number of synaptophysin immunoreactive (SYN-IR) presynaptic terminals and in the expression of the growth-associated marker GAP-43. In lines expressing moderate levels of hAPP751 or hAPP695, this effect was more prominent in homozygous than in heterozygous transgenic mice. In contrast, a line with several-fold higher levels of hAPP695 expression showed less increase in SYN-IR presynaptic terminals per amount of hAPP expressed than the lower expressor lines and a decrease in synaptotrophic effects in homozygous compared with heterozygous offspring. Transgenic mice (2-24 months of age) showed no evidence for amyloid deposits or neurodegeneration. These findings suggest that APP may be important for the formation/maintenance of synapses in vivo and that its synaptotrophic effects may be critically dependent on the expression levels of different APP isoforms. Alterations in APP expression, processing or function could contribute to the synaptic pathology seen in AD.

  12. Lactic acid induces aberrant amyloid precursor protein processing by promoting its interaction with endoplasmic reticulum chaperone proteins.

    Directory of Open Access Journals (Sweden)

    Yiwen Xiang

    Full Text Available BACKGROUND: Lactic acid, a natural by-product of glycolysis, is produced at excess levels in response to impaired mitochondrial function, high-energy demand, and low oxygen availability. The enzyme involved in the production of β-amyloid peptide (Aβ of Alzheimer's disease, BACE1, functions optimally at lower pH, which led us to investigate a potential role of lactic acid in the processing of amyloid precursor protein (APP. METHODOLOGY/PRINCIPAL FINDINGS: Lactic acid increased levels of Aβ40 and 42, as measured by ELISA, in culture medium of human neuroblastoma cells (SH-SY5Y, whereas it decreased APP metabolites, such as sAPPα. In cell lysates, APP levels were increased and APP was found to interact with ER-chaperones in a perinuclear region, as determined by co-immunoprecipitation and fluorescence microscopy studies. Lactic acid had only a very modest effect on cellular pH, did increase the levels of ER chaperones Grp78 and Grp94 and led to APP aggregate formation reminiscent of aggresomes. CONCLUSIONS/SIGNIFICANCE: These findings suggest that sustained elevations in lactic acid levels could be a risk factor in amyloidogenesis related to Alzheimer's disease through enhanced APP interaction with ER chaperone proteins and aberrant APP processing leading to increased generation of amyloid peptides and APP aggregates.

  13. Ablation of Prion Protein in Wild Type Human Amyloid Precursor Protein (APP Transgenic Mice Does Not Alter The Proteolysis of APP, Levels of Amyloid-β or Pathologic Phenotype.

    Directory of Open Access Journals (Sweden)

    Isobel J Whitehouse

    Full Text Available The cellular prion protein (PrPC has been proposed to play an important role in the pathogenesis of Alzheimer's disease. In cellular models PrPC inhibited the action of the β-secretase BACE1 on wild type amyloid precursor protein resulting in a reduction in amyloid-β (Aβ peptides. Here we have assessed the effect of genetic ablation of PrPC in transgenic mice expressing human wild type amyloid precursor protein (line I5. Deletion of PrPC had no effect on the α- and β-secretase proteolysis of the amyloid precursor protein (APP nor on the amount of Aβ38, Aβ40 or Aβ42 in the brains of the mice. In addition, ablation of PrPC did not alter Aβ deposition or histopathology phenotype in this transgenic model. Thus using this transgenic model we could not provide evidence to support the hypothesis that PrPC regulates Aβ production.

  14. Cerebral microvascular amyloid beta protein deposition induces vascular degeneration and neuroinflammation in transgenic mice expressing human vasculotropic mutant amyloid beta precursor protein.

    NARCIS (Netherlands)

    Miao, J.; Xu, F.; Davis, J.; Otte-Holler, I.; Verbeek, M.M.; Nostrand, W.E. van

    2005-01-01

    Cerebral vascular amyloid beta-protein (Abeta) deposition, also known as cerebral amyloid angiopathy, is a common pathological feature of Alzheimer's disease. Additionally, several familial forms of cerebral amyloid angiopathy exist including the Dutch (E22Q) and Iowa (D23N) mutations of Abeta. Incr

  15. Emerging roles for the amyloid precursor protein and derived peptides in the regulation of cellular and systemic metabolism.

    Science.gov (United States)

    Czeczor, Juliane K; McGee, Sean L

    2017-03-28

    The amyloid precursor protein (APP) is a transmembrane protein that can be cleaved by proteases through two different pathways to yield a number of small peptides, each with distinct physiological properties and functions. It has been extensively studied in the context of Alzheimer's disease, with the APP-derived amyloid beta (Aβ) peptide being a major constituent of the amyloid plaques observed in this disease. It has been known for some time that APP can regulate neuronal metabolism, however this review will examine evidence that APP and its peptides can also regulate key metabolic processes such as insulin action, lipid synthesis and storage and mitochondrial function in peripheral tissues. This review will present a hypothesis that amyloidogenic processing of APP in peripheral tissues plays a key role in the response to nutrient excess and that this could contribute to the pathogenesis of metabolic diseases such as obesity and type 2 diabetes (T2D). This article is protected by copyright. All rights reserved.

  16. Amyloid precursor protein-mediated endocytic pathway disruption induces axonal dysfunction and neurodegeneration.

    Science.gov (United States)

    Xu, Wei; Weissmiller, April M; White, Joseph A; Fang, Fang; Wang, Xinyi; Wu, Yiwen; Pearn, Matthew L; Zhao, Xiaobei; Sawa, Mariko; Chen, Shengdi; Gunawardena, Shermali; Ding, Jianqing; Mobley, William C; Wu, Chengbiao

    2016-05-02

    The endosome/lysosome pathway is disrupted early in the course of both Alzheimer's disease (AD) and Down syndrome (DS); however, it is not clear how dysfunction in this pathway influences the development of these diseases. Herein, we explored the cellular and molecular mechanisms by which endosomal dysfunction contributes to the pathogenesis of AD and DS. We determined that full-length amyloid precursor protein (APP) and its β-C-terminal fragment (β-CTF) act though increased activation of Rab5 to cause enlargement of early endosomes and to disrupt retrograde axonal trafficking of nerve growth factor (NGF) signals. The functional impacts of APP and its various products were investigated in PC12 cells, cultured rat basal forebrain cholinergic neurons (BFCNs), and BFCNs from a mouse model of DS. We found that the full-length wild-type APP (APPWT) and β-CTF both induced endosomal enlargement and disrupted NGF signaling and axonal trafficking. β-CTF alone induced atrophy of BFCNs that was rescued by the dominant-negative Rab5 mutant, Rab5S34N. Moreover, expression of a dominant-negative Rab5 construct markedly reduced APP-induced axonal blockage in Drosophila. Therefore, increased APP and/or β-CTF impact the endocytic pathway to disrupt NGF trafficking and signaling, resulting in trophic deficits in BFCNs. Our data strongly support the emerging concept that dysregulation of Rab5 activity contributes importantly to early pathogenesis of AD and DS.

  17. Dimerization of the transmembrane domain of amyloid precursor proteins and familial Alzheimer's disease mutants

    Directory of Open Access Journals (Sweden)

    Fraser Paul E

    2008-01-01

    Full Text Available Abstract Background Amyloid precursor protein (APP is enzymatically cleaved by γ-secretase to form two peptide products, either Aβ40 or the more neurotoxic Aβ42. The Aβ42/40 ratio is increased in many cases of familial Alzheimer's disease (FAD. The transmembrane domain (TM of APP contains the known dimerization motif GXXXA. We have investigated the dimerization of both wild type and FAD mutant APP transmembrane domains. Results Using synthetic peptides derived from the APP-TM domain, we show that this segment is capable of forming stable transmembrane dimers. A model of a dimeric APP-TM domain reveals a putative dimerization interface, and interestingly, majority of FAD mutations in APP are localized to this interface region. We find that FAD-APP mutations destabilize the APP-TM dimer and increase the population of APP peptide monomers. Conclusion The dissociation constants are correlated to both the Aβ42/Aβ40 ratio and the mean age of disease onset in AD patients. We also show that these TM-peptides reduce Aβ production and Aβ42/Aβ40 ratios when added to HEK293 cells overexpressing the Swedish FAD mutation and γ-secretase components, potentially revealing a new class of γ-secretase inhibitors.

  18. Overexpression of amyloid precursor protein increases copper content in HEK293 cells

    Energy Technology Data Exchange (ETDEWEB)

    Suazo, Miriam; Hodar, Christian; Morgan, Carlos [INTA, Laboratorio de Bioinformatica y Expresion Genica, Universidad de Chile, El Libano 5524, Macul, Santiago (Chile); Cerpa, Waldo [Centro de Envejecimiento y Regeneracion (CARE), Centro de Regulacion Celular y Patologia ' Joaquin V. Luco' (CRCP), MIFAB, Departamento de Biologia Celular y Molecular, Facultad de Ciencias Biologicas, Pontificia Universidad Catolica de Chile, Santiago (Chile); Cambiazo, Veronica [INTA, Laboratorio de Bioinformatica y Expresion Genica, Universidad de Chile, El Libano 5524, Macul, Santiago (Chile); Millenium Nucleus CGC, Universidad de Chile (Chile); Inestrosa, Nibaldo C. [Centro de Envejecimiento y Regeneracion (CARE), Centro de Regulacion Celular y Patologia ' Joaquin V. Luco' (CRCP), MIFAB, Departamento de Biologia Celular y Molecular, Facultad de Ciencias Biologicas, Pontificia Universidad Catolica de Chile, Santiago (Chile); Gonzalez, Mauricio, E-mail: mgonzale@inta.cl [INTA, Laboratorio de Bioinformatica y Expresion Genica, Universidad de Chile, El Libano 5524, Macul, Santiago (Chile)

    2009-05-15

    Amyloid precursor protein (APP) is a transmembrane glycoprotein widely expressed in mammalian tissues and plays a central role in Alzheimer's disease. However, its physiological function remains elusive. Cu{sup 2+} binding and reduction activities have been described in the extracellular APP135-156 region, which might be relevant for cellular copper uptake and homeostasis. Here, we assessed Cu{sup 2+} reduction and {sup 64}Cu uptake in two human HEK293 cell lines overexpressing APP. Our results indicate that Cu{sup 2+} reduction increased and cells accumulated larger levels of copper, maintaining cell viability at supra-physiological levels of Cu{sup 2+} ions. Moreover, wild-type cells exposed to both Cu{sup 2+} ions and APP135-155 synthetic peptides increased copper reduction and uptake. Complementation of function studies in human APP751 transformed Fre1 defective Saccharomyces cerevisiae cells rescued low Cu{sup 2+} reductase activity and increased {sup 64}Cu uptake. We conclude that Cu{sup 2+} reduction activity of APP facilitates copper uptake and may represent an early step in cellular copper homeostasis.

  19. Regulation of amyloid precursor protein processing by the Beclin 1 complex.

    Directory of Open Access Journals (Sweden)

    Philipp A Jaeger

    Full Text Available Autophagy is an intracellular degradation pathway that functions in protein and organelle turnover in response to starvation and cellular stress. Autophagy is initiated by the formation of a complex containing Beclin 1 (BECN1 and its binding partner Phosphoinositide-3-kinase, class 3 (PIK3C3. Recently, BECN1 deficiency was shown to enhance the pathology of a mouse model of Alzheimer Disease (AD. However, the mechanism by which BECN1 or autophagy mediate these effects are unknown. Here, we report that the levels of Amyloid precursor protein (APP and its metabolites can be reduced through autophagy activation, indicating that they are a substrate for autophagy. Furthermore, we find that knockdown of Becn1 in cell culture increases the levels of APP and its metabolites. Accumulation of APP and APP C-terminal fragments (APP-CTF are accompanied by impaired autophagosomal clearance. Pharmacological inhibition of autophagosomal-lysosomal degradation causes a comparable accumulation of APP and APP-metabolites in autophagosomes. Becn1 reduction in cell culture leads to lower levels of its binding partner Pik3c3 and increased presence of Microtubule-associated protein 1, light chain 3 (LC3. Overexpression of Becn1, on the other hand, reduces cellular APP levels. In line with these observations, we detected less BECN1 and PIK3C3 but more LC3 protein in brains of AD patients. We conclude that BECN1 regulates APP processing and turnover. BECN1 is involved in autophagy initiation and autophagosome clearance. Accordingly, BECN1 deficiency disrupts cellular autophagy and autophagosomal-lysosomal degradation and alters APP metabolism. Together, our findings suggest that autophagy and the BECN1-PIK3C3 complex regulate APP processing and play an important role in AD pathology.

  20. Protective effects of ferulic acid in amyloid precursor protein plus presenilin-1 transgenic mouse model of Alzheimer disease.

    Science.gov (United States)

    Yan, Ji-Jing; Jung, Jun-Sub; Kim, Taek-Keun; Hasan, Ashraful; Hong, Chang-Won; Nam, Ju-Suk; Song, Dong-Keun

    2013-01-01

    We previously reported the protective effects of long-term administration of ferulic acid against the in vivo toxicity of β-amyloid peptide administered intracerebroventricularly in mice. In the present study, we investigated the effects of ferulic acid in transgenic amyloid precursor protein (APP)swe/presenilin 1 (PS1)dE9 (APP/PS1) mouse model of Alzheimer disease (AD). Chronic (for 6 months from the age of 6 to 12 months) oral administration of ferulic acid at a dose of 5.3 mg/kg/day significantly enhanced the performance in novel-object recognition task, and reduced amyloid deposition and interleukin-1 beta (IL-1β) levels in the frontal cortex. These results suggest that ferulic acid at a certain dosage could be useful for prevention and treatment of AD.

  1. Glial expression of the {beta}-Amyloid Precursor Protein (APP) in global ischemia

    Energy Technology Data Exchange (ETDEWEB)

    Banati, R.B.; Gehrmann, J.; Kreutzberg, G.W. [Max Planck Institute of Psychiarty, Martinsried (Germany)]|[Max Planck Institute for Neurological Research, Koeln (Germany)]|[Univ. Hospital, Zurich (Switzerland)

    1995-07-01

    The {beta}-amyloid precursor protein (APP) bears characteristics of an acute-phase protein and therefore is likely to be involved in the glial response to brain injury. In the brain, APP is rapidly synthesized by activated glial cells in response to comparatively mild neuronal lesions, e.g., a remote peripheral nerve injury. Perfusion deficits in the brain result largely in neuronal necrosis and are a common condition in elderly patients. This neuronal necrosis is accompanied by a pronounced reaction of astrocytes and microglia, which can also be observed in animal models. We have therefore studied in the rat, immunocytochemically, the induction of APP after 30 min of global ischemia caused by four-vessel occlusion. The postischemic brain injuries were examined at survival times from 12 h to 7 days. From day 3 onward, APP immunoreactivity was strongly induced in the CA{sub 1} and CA{sub 4} regions of the rat dorsal hippocampus as well as in the dorsolateral striatum. In these areas, the majority of APP-immunoreactive cells were reactive glial fibrillary acidic protein (GFAP)-positive astrocytes, as shown by double-immunofluorescence labeling for GFAP and APP. Additionally, small ramified cells, most likely activated microglia, expressed APP immunoreactivity. In contrast, in the parietal cortex, APP immunoreactivity occurred focally in clusters of activated microglia rather than in astrocytes, as demonstrated by double-immunofluorescence labeling for APP and the microglia-binding lectin Griffonia simplicifolia isolectin B{sub 4}. In conclusion, following global ischemia, APP is induced in reactive glial cells with spatial differences in the distribution pattern of APP induction in actrocytes and microglia. 51 refs., 4 figs.

  2. Mutation analysis of presenilin-1 gene in Alzheimer’s disease patients and the effects of its mutation on expression of presenilin-1 and amyloid precursor protein

    Institute of Scientific and Technical Information of China (English)

    刘晓雄

    2013-01-01

    Objective To analyze the presenilin-1(PS-1) gene mutations in Alzheimer’s disease(AD) patients and investigate the influence of the initiation codon mutation on the mRNA expression of PS-1 and amyloid precursor protein

  3. Effect of catalpol on senile plaques and spatial learning and memory ability in amyloidprotein precursor/presenilin 1 double transgenic mice

    Institute of Scientific and Technical Information of China (English)

    宋冲

    2013-01-01

    Objective To investigate whether catalpol affects senile plaque formation and spatial learning and memory ability in the amyloid-βprotein precursor/presenilin 1(APP/PS1)double transgenic mice.Methods

  4. Inhibiting p38 mitogen-activated protein kinase attenuates cerebral ischemic injury in Swedish mutant amyloid precursor protein transgenic mice

    Institute of Scientific and Technical Information of China (English)

    Liangyu Zou; Haiyan Qin; Yitao He; Heming Huang; Yi Lu; Xiaofan Chu

    2012-01-01

    Cerebral ischemia was induced using photothrombosis 1 hour after intraperitoneal injection of the p38 mitogen-activated protein kinase (MAPK) inhibitor SB239063 into Swedish mutant amyloid precursor protein (APP/SWE) transgenic and non-transgenic mice. The number of surviving neurons in the penumbra was quantified using Nissl staining, and the activity of p38 MAPKs was measured by western blotting. The number of surviving neurons in the penumbra was significantly reduced in APP/SWE transgenic mice compared with non-transgenic controls 7 days after cerebral ischemia, but the activity of p38 MAPKs was significantly elevated compared with the non-ischemic hemisphere in the APP/SWE transgenic mice. SB239063 prevented these changes. The APP/SWE mutation exacerbated ischemic brain injury, and this could be alleviated by inhibiting p38 MAPK activity.

  5. Calcium ionophore A23187 specifically decreases the secretion of beta-secretase cleaved amyloid precursor protein during apoptosis in primary rat cortical cultures

    DEFF Research Database (Denmark)

    Sennvik, K; Benedikz, Eirikur; Fastbom, J;

    2001-01-01

    Alzheimer's disease (AD) is characterized by the degeneration and loss of neurons, intracellular neurofibrillary tangles and the accumulation of extracellular senile plaques consisting mainly of beta-amyloid (A beta). A beta is generated from the amyloid precursor protein (APP) by sequential beta...

  6. Soluble beta-amyloid precursor protein is related to disease progression in amyotrophic lateral sclerosis.

    Directory of Open Access Journals (Sweden)

    Petra Steinacker

    Full Text Available BACKGROUND: Biomarkers of disease progression in amyotrophic lateral sclerosis (ALS could support the identification of beneficial drugs in clinical trials. We aimed to test whether soluble fragments of beta-amyloid precursor protein (sAPPα and sAPPß correlated with clinical subtypes of ALS and were of prognostic value. METHODOLOGY/PRINCIPAL FINDINGS: In a cross-sectional study including patients with ALS (N = 68 with clinical follow-up data over 6 months, Parkinson's disease (PD, N = 20, and age-matched controls (N = 40, cerebrospinal fluid (CSF levels of sAPPα a, sAPPß and neurofilaments (NfH(SMI35 were measured by multiplex assay, Progranulin by ELISA. CSF sAPPα and sAPPß levels were lower in ALS with a rapidly-progressive disease course (p = 0.03, and p = 0.02 and with longer disease duration (p = 0.01 and p = 0.01, respectively. CSF NfH(SMI35 was elevated in ALS compared to PD and controls, with highest concentrations found in patients with rapid disease progression (p<0.01. High CSF NfH(SMI3 was linked to low CSF sAPPα and sAPPß (p = 0.001, and p = 0.007, respectively. The ratios CSF NfH(SMI35/CSF sAPPα,-ß were elevated in patients with fast progression of disease (p = 0.002 each. CSF Progranulin decreased with ongoing disease (p = 0.04. CONCLUSIONS: This study provides new CSF candidate markers associated with progression of disease in ALS. The data suggest that a deficiency of cellular neuroprotective mechanisms (decrease of sAPP is linked to progressive neuro-axonal damage (increase of NfH(SMI35 and to progression of disease.

  7. Metabolic Characterization of Intact Cells Reveals Intracellular Amyloid Beta but Not Its Precursor Protein to Reduce Mitochondrial Respiration

    Science.gov (United States)

    Schaefer, Patrick M.; von Einem, Bjoern; Walther, Paul; Calzia, Enrico; von Arnim, Christine A. F.

    2016-01-01

    One hallmark of Alzheimer´s disease are senile plaques consisting of amyloid beta (Aβ), which derives from the processing of the amyloid precursor protein (APP). Mitochondrial dysfunction has been linked to the pathogenesis of Alzheimer´s disease and both Aβ and APP have been reported to affect mitochondrial function in isolated systems. However, in intact cells, considering a physiological localization of APP and Aβ, it is pending what triggers the mitochondrial defect. Thus, the aim of this study was to dissect the impact of APP versus Aβ in inducing mitochondrial alterations with respect to their subcellular localization. We performed an overexpression of APP or beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), increasing APP and Aβ levels or Aβ alone, respectively. Conducting a comprehensive metabolic characterization we demonstrate that only APP overexpression reduced mitochondrial respiration, despite lower extracellular Aβ levels compared to BACE overexpression. Surprisingly, this could be rescued by a gamma secretase inhibitor, oppositionally indicating an Aβ-mediated mitochondrial toxicity. Analyzing Aβ localization revealed that intracellular levels of Aβ and an increased spatial association of APP/Aβ with mitochondria are associated with reduced mitochondrial respiration. Thus, our data provide marked evidence for a prominent role of intracellular Aβ accumulation in Alzheimer´s disease associated mitochondrial dysfunction. Thereby it highlights the importance of the localization of APP processing and intracellular transport as a decisive factor for mitochondrial function, linking two prominent hallmarks of neurodegenerative diseases. PMID:28005987

  8. Iron-export ferroxidase activity of β-amyloid precursor protein is inhibited by zinc in Alzheimer's disease.

    Science.gov (United States)

    Duce, James A; Tsatsanis, Andrew; Cater, Michael A; James, Simon A; Robb, Elysia; Wikhe, Krutika; Leong, Su Ling; Perez, Keyla; Johanssen, Timothy; Greenough, Mark A; Cho, Hyun-Hee; Galatis, Denise; Moir, Robert D; Masters, Colin L; McLean, Catriona; Tanzi, Rudolph E; Cappai, Roberto; Barnham, Kevin J; Ciccotosto, Giuseppe D; Rogers, Jack T; Bush, Ashley I

    2010-09-17

    Alzheimer's Disease (AD) is complicated by pro-oxidant intraneuronal Fe(2+) elevation as well as extracellular Zn(2+) accumulation within amyloid plaque. We found that the AD β-amyloid protein precursor (APP) possesses ferroxidase activity mediated by a conserved H-ferritin-like active site, which is inhibited specifically by Zn(2+). Like ceruloplasmin, APP catalytically oxidizes Fe(2+), loads Fe(3+) into transferrin, and has a major interaction with ferroportin in HEK293T cells (that lack ceruloplasmin) and in human cortical tissue. Ablation of APP in HEK293T cells and primary neurons induces marked iron retention, whereas increasing APP695 promotes iron export. Unlike normal mice, APP(-/-) mice are vulnerable to dietary iron exposure, which causes Fe(2+) accumulation and oxidative stress in cortical neurons. Paralleling iron accumulation, APP ferroxidase activity in AD postmortem neocortex is inhibited by endogenous Zn(2+), which we demonstrate can originate from Zn(2+)-laden amyloid aggregates and correlates with Aβ burden. Abnormal exchange of cortical zinc may link amyloid pathology with neuronal iron accumulation in AD.

  9. Influence of apolipoprotein E and its receptors on cerebral amyloid precursor protein metabolism following traumatic brain injury

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shuai; SUN Xiao-chuan

    2012-01-01

    Traumatic brain injury (TBI) is the leading cause of mortality and disability among young individuals in our society,and globally the incidence of TBI is rising sharply.Mounting evidence has indicated that apolipoprotein E (apoE:protein; APOE:gene) genotype influences the outcome after TBI.The proposed mechanism by which APOE affects the clinicopathological consequences of TBI is multifactorial and includes amyloid deposition,disruption of lipid distribution,dysfunction of mitochondrial energy production,oxidative stress and increases intracellular calcium in response to injury.This paper reviews the current state of knowledge regarding the influence of apoE and its receptors on cerebral amyloid betaprotein precursor metabolism following TBI.

  10. N-Acetyl-L-Cystein downregulates beta-amyloid precursor protein gene transcription in human neuroblastoma cells.

    Science.gov (United States)

    Studer, R; Baysang, G; Brack, C

    2001-01-01

    The causes for the sporadic form of Alzheimer's disease (AD) are still poorly understood, except from the fact that age is an important risk factor. The main component of the characteristic amyloid plaques in brains of AD patients are Abeta peptides, derivatives of the amyloid precursor protein APP. Oxidative stress may contribute to the aetiology of AD by dysregulation of APP metabolism. Overexpression of the APP gene could result in an increased secretion of neurotoxic Abeta peptides, while preventing the overexpression might be protective. We here report that the antioxidant N-Acetyl-L-Cystein (NAC) downregulates APP gene transcription in human neuroblastoma cells. The effect is reversible when cells are returned to NAC free medium. These results open up new possibilities for the development of therapeutic agents that intervene at the transcriptional level.

  11. Alzheimer's disease therapeutics targeted to the control of amyloid precursor protein translation: maintenance of brain iron homeostasis.

    Science.gov (United States)

    Bandyopadhyay, Sanghamitra; Rogers, Jack T

    2014-04-15

    The neurotoxicity of amyloid beta (Aβ), a major cleavage product of the amyloid precursor protein (APP), is enhanced by iron, as found in the amyloid plaques of Alzheimer's disease (AD) patients. By contrast, the long-known neuroprotective activity of APP is evident after α-secretase cleavage of the precursor to release sAPPα, and depends on the iron export actions of APP itself. The latter underlie its neurotrophic and protective effects in facilitating the homeostatic actions of ferroportin mediated-iron export. Thus APP-dependent iron export may alleviate oxidative stress by minimizing labile iron thus protecting neurons from iron overload during stroke and hemorrhage. Consistent with this, altered phosphorylation of iron-regulatory protein-1 (IRP1) and its signaling processes play a critical role in modulating APP translation via the 5' untranslated region (5'UTR) of its transcript. The APP 5'UTR region encodes a functional iron-responsive element (IRE) RNA stem loop that represents a potential target for modulating APP production. Targeted regulation of APP gene expression via the modulation of 5'UTR sequence function represents a novel approach for the potential treatment of AD since altering APP translation can be used to improve both the protective brain iron balance and provide anti-amyloid efficacy. Approved drugs including paroxetine and desferrioxamine and several novel compounds have been identified that suppress abnormal metal-promoted Aβ accumulation with a subset of these acting via APP 5'UTR-dependent mechanisms to modulate APP translation and cleavage to generate the non-toxic sAPPα.

  12. Exercise is more effective than diet control in preventing high fat diet-induced β-amyloid deposition and memory deficit in amyloid precursor protein transgenic mice.

    Science.gov (United States)

    Maesako, Masato; Uemura, Kengo; Kubota, Masakazu; Kuzuya, Akira; Sasaki, Kazuki; Hayashida, Naoko; Asada-Utsugi, Megumi; Watanabe, Kiwamu; Uemura, Maiko; Kihara, Takeshi; Takahashi, Ryosuke; Shimohama, Shun; Kinoshita, Ayae

    2012-06-29

    Accumulating evidence suggests that some dietary patterns, specifically high fat diet (HFD), increase the risk of developing sporadic Alzheimer disease (AD). Thus, interventions targeting HFD-induced metabolic dysfunctions may be effective in preventing the development of AD. We previously demonstrated that amyloid precursor protein (APP)-overexpressing transgenic mice fed HFD showed worsening of cognitive function when compared with control APP mice on normal diet. Moreover, we reported that voluntary exercise ameliorates HFD-induced memory impairment and β-amyloid (Aβ) deposition. In the present study, we conducted diet control to ameliorate the metabolic abnormality caused by HFD on APP transgenic mice and compared the effect of diet control on cognitive function with that of voluntary exercise as well as that of combined (diet control plus exercise) treatment. Surprisingly, we found that exercise was more effective than diet control, although both exercise and diet control ameliorated HFD-induced memory deficit and Aβ deposition. The production of Aβ was not different between the exercise- and the diet control-treated mice. On the other hand, exercise specifically strengthened the activity of neprilysin, the Aβ-degrading enzyme, the level of which was significantly correlated with that of deposited Aβ in our mice. Notably, the effect of the combination treatment (exercise and diet control) on memory and amyloid pathology was not significantly different from that of exercise alone. These studies provide solid evidence that exercise is a useful intervention to rescue HFD-induced aggravation of cognitive decline in transgenic model mice of AD.

  13. Complement C3 deficiency leads to accelerated amyloid beta plaque deposition and neurodegeneration and modulation of the microglia/macrophage phenotype in amyloid precursor protein transgenic mice.

    Science.gov (United States)

    Maier, Marcel; Peng, Ying; Jiang, Liying; Seabrook, Timothy J; Carroll, Michael C; Lemere, Cynthia A

    2008-06-18

    Complement factor C3 is the central component of the complement system and a key inflammatory protein activated in Alzheimer's disease (AD). Previous studies demonstrated that inhibition of C3 by overexpression of soluble complement receptor-related protein y in an AD mouse model led to reduced microgliosis, increased amyloid beta (Abeta) plaque burden, and neurodegeneration. To further address the role of C3 in AD pathology, we generated a complement C3-deficient amyloid precursor protein (APP) transgenic AD mouse model (APP;C3(-/-)). Brains were analyzed at 8, 12, and 17 months of age by immunohistochemical and biochemical methods and compared with age-matched APP transgenic mice. At younger ages (8-12 months), no significant neuropathological differences were observed between the two transgenic lines. In contrast, at 17 months of age, APP;C3(-/-) mice showed significant changes of up to twofold increased total Abeta and fibrillar amyloid plaque burden in midfrontal cortex and hippocampus, which correlated with (1) significantly increased Tris-buffered saline (TBS)-insoluble Abeta(42) levels and reduced TBS-soluble Abeta(42) and Abeta(40) levels in brain homogenates, (2) a trend for increased Abeta levels in the plasma, (3) a significant loss of neuronal-specific nuclear protein-positive neurons in the hippocampus, and (4) differential activation of microglia toward a more alternative phenotype (e.g., significantly increased CD45-positive microglia, increased brain levels of interleukins 4 and 10, and reduced levels of CD68, F4/80, inducible nitric oxide synthase, and tumor necrosis factor). Our results suggest a beneficial role for complement C3 in plaque clearance and neuronal health as well as in modulation of the microglia phenotype.

  14. Schisandrin B protects PC12 cells by decreasing the expression of amyloid precursor protein and vacuolar protein sorting 35★

    OpenAIRE

    Yan, Mingmin; Mao, Shanping; Dong, Huimin; Liu, Baohui; Zhang, Qian; PAN, GAOFENG; Fu, Zhiping

    2012-01-01

    PC12 cell injury was induced using 20 μM amyloid β-protein 25–35 to establish a model of Alzheimer's disease. The cells were then treated with 5, 10, and 25 μM Schisandrin B. Methylthiazolyldiphenyl-tetrazolium bromide assays and Hoechst 33342 staining results showed that with increasing Schisandrin B concentration, the survival rate of PC12 cells injured by amyloid β-protein 25–35 gradually increased and the rate of apoptosis gradually decreased. Reverse transcription-PCR, immunocytochemical...

  15. Baicalein reduces β-amyloid and promotes nonamyloidogenic amyloid precursor protein processing in an Alzheimer’s disease transgenic mouse model

    Science.gov (United States)

    Zhang, She-Qing; Obregon, Demian; Ehrhart, Jared; Deng, Juan; Tian, Jun; Hou, Huayan; Giunta, Brian; Sawmiller, Darrell; Tan, Jun

    2013-01-01

    Baicalein, a flavonoid isolated from the roots of Scutellaria baicalensis, is known to modulate γ-aminobutyric acid (GABA) type A receptors. Given prior reports demonstrating benefits of GABAA modulation for Alzheimer’s disease (AD) treatment, we wished to determine whether this agent might be beneficial for AD. CHO cells engineered to overexpress wild-type amyloid precursor protein (APP), primary culture neuronal cells from AD mice (Tg2576) and AD mice were treated with baicalein. In the cell cultures, baicalein significantly reduced the production of β-amyloid (Aβ) by increasing APP α-processing. These effects were blocked by the GABAA antagonist bicuculline. Likewise, AD mice treated daily with i.p. baicalein for 8 weeks showed enhanced APP α-secretase processing, reduced Aβ production, and reduced AD-like pathology together with improved cognitive performance. Our findings suggest that baicalein promotes nonamyloidogenic processing of APP, thereby reducing Aβ production and improving cognitive performance, by activating GABAA receptors. © 2013 Wiley Periodicals, Inc. PMID:23686791

  16. P-glycoprotein efflux and other factors limit brain amyloid beta reduction by beta-site amyloid precursor protein-cleaving enzyme 1 inhibitors in mice.

    Science.gov (United States)

    Meredith, Jere E; Thompson, Lorin A; Toyn, Jeremy H; Marcin, Lawrence; Barten, Donna M; Marcinkeviciene, Jovita; Kopcho, Lisa; Kim, Young; Lin, Alan; Guss, Valerie; Burton, Catherine; Iben, Lawrence; Polson, Craig; Cantone, Joe; Ford, Michael; Drexler, Dieter; Fiedler, Tracey; Lentz, Kimberley A; Grace, James E; Kolb, Janet; Corsa, Jason; Pierdomenico, Maria; Jones, Kelli; Olson, Richard E; Macor, John E; Albright, Charles F

    2008-08-01

    Alzheimer's disease (AD) is a progressive neurodegenerative disease. Amyloid beta (Abeta) peptides are hypothesized to cause the initiation and progression of AD based on pathologic data from AD patients, genetic analysis of mutations that cause early onset forms of AD, and preclinical studies. Based on this hypothesis, beta-site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1) inhibitors are an attractive therapeutic approach for AD because cleavage of the APP by BACE1 is required to form Abeta. In this study, three potent BACE1 inhibitors are characterized. All three inhibitors decrease Abeta formation in cultured cells with IC(50) values less than 10 nM. Analysis of APP C-terminal fragments by immunoblotting and Abeta peptides by mass spectrometry showed that these inhibitors decreased Abeta by inhibiting BACE1. An assay for Abeta1-40 in mice was developed and used to show that these BACE1 inhibitors decreased plasma Abeta1-40, but not brain Abeta1-40, in wild-type mice. Because these BACE1 inhibitors were substrates for P-glycoprotein (P-gp), a member of the ATP-binding cassette superfamily of efflux transporters, these inhibitors were administered to P-gp knockout (KO) mice. These studies showed that all three BACE1 inhibitors decreased brain Abeta1-40 in P-gp KO mice, demonstrating that P-gp is a major limitation for development of BACE1 inhibitors to test the amyloid hypothesis. A comparison of plasma Abeta1-40 and brain Abeta1-40 dose responses for these three compounds revealed differences in relative ED(50) values, indicating that factors other than P-gp can also contribute to poor brain activity by BACE1 inhibitors.

  17. The purinergic receptor P2X7 triggers alpha-secretase-dependent processing of the amyloid precursor protein.

    Science.gov (United States)

    Delarasse, Cécile; Auger, Rodolphe; Gonnord, Pauline; Fontaine, Bertrand; Kanellopoulos, Jean M

    2011-01-28

    The amyloid precursor protein (APP) is cleaved by β- and γ-secretases to generate the β-amyloid (Aβ) peptides, which are present in large amounts in the amyloid plaques of Alzheimer disease (AD) patient brains. Non-amyloidogenic processing of APP by α-secretases leads to proteolytic cleavage within the Aβ peptide sequence and shedding of the soluble APP ectodomain (sAPPα), which has been reported to be endowed with neuroprotective properties. In this work, we have shown that activation of the purinergic receptor P2X7 (P2X7R) stimulates sAPPα release from mouse neuroblastoma cells expressing human APP, from human neuroblastoma cells and from mouse primary astrocytes or neural progenitor cells. sAPPα shedding is inhibited by P2X7R antagonists or knockdown of P2X7R with specific small interfering RNA (siRNA) and is not observed in neural cells from P2X7R-deficient mice. P2X7R-dependent APP-cleavage is independent of extracellular calcium and strongly inhibited by hydroxamate-based metalloprotease inhibitors, TAPI-2 and GM6001. However, knockdown of a disintegrin and metalloproteinase-9 (ADAM9), ADAM10 and ADAM17 by specific siRNA, known to have α-secretase activity, does not block the P2X7R-dependent non-amyloidogenic pathway. Using several specific pharmacological inhibitors, we demonstrate that the mitogen-activated protein kinase modules Erk1/2 and JNK are involved in P2X7R-dependent α-secretase activity. Our study suggests that P2X7R, which is expressed in hippocampal neurons and glial cells, is a potential therapeutic target in AD.

  18. Two memory associated genes regulated by amyloid precursor protein intracellular domain ovel insights into the pathogenesis of learning and memory impairment in Alzheimer's disease

    Institute of Scientific and Technical Information of China (English)

    Chuandong Zheng; Xi Gu; Zhimei Zhong; Rui Zhu; Tianming Gao; Fang Wang

    2012-01-01

    In this study, we employed chromatin immunoprecipitation, a useful method for studying the locations of transcription factors bound to specific DNA regions in specific cells, to investigate amyloid precursor protein intracellular domain binding sites in chromatin DNA from hippocampal neurons of rats, and to screen out five putative genes associated with the learning and memory functions. The promoter regions of the calcium/calmodulin-dependent protein kinase II alpha and glutamate receptor-2 genes were amplified by PCR from DNA products immunoprecipitated by amyloid precursor protein intracellular domain. An electrophoretic mobility shift assay and western blot analysis suggested that the promoter regions of these two genes associated with learning and memory were bound by amyloid precursor protein intracellular domain (in complex form). Our experimental findings indicate that the amyloid precursor protein intracellular domain is involved in the transcriptional regulation of learning- and memory-associated genes in hippocampal neurons. These data may provide new insights into the molecular mechanism underlying the symptoms of progressive memory loss in Alzheimer's disease.

  19. The Amyloid Precursor Protein of Alzheimer's Disease in the Reduction of Copper(II) to Copper(I)

    Science.gov (United States)

    Multhaup, Gerd; Schlicksupp, Andrea; Hesse, Lars; Beher, Dirk; Ruppert, Thomas; Masters, Colin L.; Beyreuther, Konrad

    1996-03-01

    The transition metal ion copper(II) has a critical role in chronic neurologic diseases. The amyloid precursor protein (APP) of Alzheimer's disease or a synthetic peptide representing its copper-binding site reduced bound copper(II) to copper(I). This copper ion-mediated redox reaction led to disulfide bond formation in APP, which indicated that free sulfhydryl groups of APP were involved. Neither superoxide nor hydrogen peroxide had an effect on the kinetics of copper(II) reduction. The reduction of copper(II) to copper(I) by APP involves an electron-transfer reaction and could enhance the production of hydroxyl radicals, which could then attack nearby sites. Thus, copper-mediated toxicity may contribute to neurodegeneration in Alzheimer's disease.

  20. Caffeine, Through Adenosine A3 Receptor-Mediated Actions, Suppresses AmyloidProtein Precursor Internalization and Amyloid-β Generation.

    Science.gov (United States)

    Li, Shanshan; Geiger, Nicholas H; Soliman, Mahmoud L; Hui, Liang; Geiger, Jonathan D; Chen, Xuesong

    2015-01-01

    Intraneuronal accumulation and extracellular deposition of amyloid-β (Aβ) protein continues to be implicated in the pathogenesis of Alzheimer's disease (AD), be it familial in origin or sporadic in nature. Aβ is generated intracellularly following endocytosis of amyloidprotein precursor (AβPP), and, consequently, factors that suppress AβPP internalization may decrease amyloidogenic processing of AβPP. Here we tested the hypothesis that caffeine decreases Aβ generation by suppressing AβPP internalization in primary cultured neurons. Caffeine concentration-dependently blocked low-density lipoprotein (LDL) cholesterol internalization and a specific adenosine A3 receptor (A3R) antagonist as well as siRNA knockdown of A3Rs mimicked the effects of caffeine on neuronal internalization of LDL cholesterol. Further implicating A3Rs were findings that a specific A3R agonist increased neuronal internalization of LDL cholesterol. In addition, caffeine as well as siRNA knockdown of A3Rs blocked the ability of LDL cholesterol to increase Aβ levels. Furthermore, caffeine blocked LDL cholesterol-induced decreases in AβPP protein levels in neuronal plasma membranes, increased surface expression of AβPP on neurons, and the A3R antagonist as well as siRNA knockdown of A3Rs mimicked the effects of caffeine on AβPP surface expression. Moreover, the A3R agonist decreased neuronal surface expression of AβPP. Our findings suggest that caffeine exerts protective effects against amyloidogenic processing of AβPP at least in part by suppressing A3R-mediated internalization of AβPP.

  1. Nerve Growth Factor Increases mRNA Levels for the Prion Protein and the β -amyloid Protein Precursor in Developing Hamster Brain

    Science.gov (United States)

    Mobley, William C.; Neve, Rachael L.; Prusiner, Stanley B.; McKinley, Michael P.

    1988-12-01

    Deposition of amyloid filaments serves as a pathologic hallmark for some neurodegenerative disorders. The prion protein (PrP) is found in amyloid of animals with scrapie and humans with Creutzfeldt-Jakob disease; the β protein is present in amyloid deposits in Alzheimer disease and Down syndrome patients. These two proteins are derived from precursors that in the brain are expressed primarily in neurons and are membrane bound. We found that gene expression for PrP and the β -protein precursor (β -PP) is regulated in developing hamster brain. Specific brain regions showed distinct patterns of ontogenesis for PrP and β -PP mRNAs. The increases in PrP and β -PP mRNAs in developing basal forebrain coincided with an increase in choline acetyltransferase activity, raising the possibility that these markers might be coordinately controlled in cholinergic neurons and regulated by nerve growth factor (NGF). Injections of NGF into the brains of neonatal hamsters increased both PrP and β -PP mRNA levels. Increased PrP and β -PP mRNA levels induced by NGF were confined to regions that contain NGF-responsive cholinergic neurons and were accompanied by elevations in choline acetyltransferase. It remains to be established whether or not exogenous NGF acts to increase PrP and β -PP gene expression selectively in forebrain cholinergic neurons in the developing hamster and endogenous NGF regulates expression of these genes.

  2. Y682 mutation of amyloid precursor protein promotes endo-lysosomal dysfunction by disrupting APP-SorLA interaction

    Directory of Open Access Journals (Sweden)

    Luca Rosario La Rosa

    2015-04-01

    Full Text Available The intracellular transport and localization of amyloid precursor protein (APP are critical determinants of APP processing and β-amyloid peptide production, thus crucially important for the pathophysiology of Alzheimer’s disease (AD. Notably, the C-terminal Y682ENPTY687 domain of APP binds to specific adaptors controlling APP trafficking and sorting in neurons. Mutation on the Y682 residue to glycine (Y682G leads to altered APP sorting in hippocampal neurons that favors its accumulation in intracellular compartments and the release of soluble APPα. Such alterations induce premature aging and learning and cognitive deficits in APP Y682G mutant mice (APPYG/YG. Here, we report that Y682G mutation affects formation of the APP complex with sortilin-related receptor (SorLA, resulting in endo-lysosomal dysfunctions and neuronal degeneration. Moreover, disruption of the APP/SorLA complex changes the trafficking pathway of SorLA, with its consequent increase in secretion outside neurons. Mutations in the SorLA gene are a prognostic factor in AD, and increases in SorLA levels in cerebrospinal fluid are predictive of AD in humans. These results might open new possibilities in comprehending the role played by SorLA in its interaction with APP and in the progression of neuronal degeneration. In addition, they further underline the crucial role played by Y682 residue in controlling APP trafficking in neurons.

  3. Tetrahydrohyperforin Inhibits the Proteolytic Processing of Amyloid Precursor Protein and Enhances Its Degradation by Atg5-Dependent Autophagy.

    Directory of Open Access Journals (Sweden)

    Viviana A Cavieres

    Full Text Available Alzheimer's disease (AD is a neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ peptide. We have previously shown that the compound tetrahydrohyperforin (IDN5706 prevents accumulation of Aβ species in an in vivo model of AD, however the mechanism that explains this reduction is not well understood. We show herein that IDN5706 decreases the levels of ER degradation enhancer, mannosidase alpha-like 1 (EDEM1, a key chaperone related to endoplasmic-reticulum-associated degradation (ERAD. Moreover, we observed that low levels of EDEM1 correlated with a strong activation of autophagy, suggesting a crosstalk between these two pathways. We observed that IDN5706 perturbs the glycosylation and proteolytic processing of the amyloid precursor protein (APP, resulting in the accumulation of immature APP (iAPP in the endoplasmic reticulum. To investigate the contribution of autophagy, we tested the effect of IDN5706 in Atg5-depleted cells. We found that depletion of Atg5 enhanced the accumulation of iAPP in response to IDN5706 by slowing down its degradation. Our findings reveal that IDN5706 promotes degradation of iAPP via the activation of Atg5-dependent autophagy, shedding light on the mechanism that may contribute to the reduction of Aβ production in vivo.

  4. Tetrahydrohyperforin Inhibits the Proteolytic Processing of Amyloid Precursor Protein and Enhances Its Degradation by Atg5-Dependent Autophagy

    Science.gov (United States)

    Muñoz, Vanessa C.; Yefi, Claudia P.; Bustamante, Hianara A.; Barraza, Rafael R.; Tapia-Rojas, Cheril; Otth, Carola; Barrera, María José; González, Carlos; Mardones, Gonzalo A.; Inestrosa, Nibaldo C.; Burgos, Patricia V.

    2015-01-01

    Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) peptide. We have previously shown that the compound tetrahydrohyperforin (IDN5706) prevents accumulation of Aβ species in an in vivo model of AD, however the mechanism that explains this reduction is not well understood. We show herein that IDN5706 decreases the levels of ER degradation enhancer, mannosidase alpha-like 1 (EDEM1), a key chaperone related to endoplasmic-reticulum-associated degradation (ERAD). Moreover, we observed that low levels of EDEM1 correlated with a strong activation of autophagy, suggesting a crosstalk between these two pathways. We observed that IDN5706 perturbs the glycosylation and proteolytic processing of the amyloid precursor protein (APP), resulting in the accumulation of immature APP (iAPP) in the endoplasmic reticulum. To investigate the contribution of autophagy, we tested the effect of IDN5706 in Atg5-depleted cells. We found that depletion of Atg5 enhanced the accumulation of iAPP in response to IDN5706 by slowing down its degradation. Our findings reveal that IDN5706 promotes degradation of iAPP via the activation of Atg5-dependent autophagy, shedding light on the mechanism that may contribute to the reduction of Aβ production in vivo. PMID:26308941

  5. Multiplex assay for live-cell monitoring of cellular fates of amyloidprecursor protein (APP.

    Directory of Open Access Journals (Sweden)

    Maria Merezhko

    Full Text Available Amyloidprecursor protein (APP plays a central role in pathogenesis of Alzheimer's disease. APP has a short half-life and undergoes complex proteolytic processing that is highly responsive to various stimuli such as changes in cellular lipid or energy homeostasis. Cellular trafficking of APP is controlled by its large protein interactome, including dozens of cytosolic adaptor proteins, and also by interactions with lipids. Currently, cellular regulation of APP is mostly studied based on appearance of APP-derived proteolytic fragments to conditioned media and cellular extracts. Here, we have developed a novel live-cell assay system based on several indirect measures that reflect altered APP trafficking and processing in cells. Protein-fragment complementation assay technology for detection of APP-BACE1 protein-protein interaction forms the core of the new assay. In a multiplex form, the assay can measure four endpoints: total cellular APP level, total secreted sAPP level in media, APP-BACE1 interaction in cells and in exosomes released by the cells. Functional validation of the assay with pharmacological and genetic tools revealed distinct patterns of cellular fates of APP, with immediate mechanistic implications. This new technology will facilitate functional genomics studies of late-onset Alzheimer's disease, drug discovery efforts targeting APP and characterization of the physiological functions of APP and its proteolytic fragments.

  6. BECN1/Beclin 1 sorts cell-surface APP/amyloid β precursor protein for lysosomal degradation.

    Science.gov (United States)

    Swaminathan, Gayathri; Zhu, Wan; Plowey, Edward D

    2016-12-01

    The regulation of plasma membrane (PM)-localized transmembrane protein/receptor trafficking has critical implications for cell signaling, metabolism and survival. In this study, we investigated the role of BECN1 (Beclin 1) in the degradative trafficking of PM-associated APP (amyloid β precursor protein), whose metabolism to amyloid-β, an essential event in Alzheimer disease, is dependent on divergent PM trafficking pathways. We report a novel interaction between PM-associated APP and BECN1 that recruits macroautophagy/endosomal regulatory proteins PIK3C3 and UVRAG. We found that BECN1 promotes surface APP internalization and sorting predominantly to endosomes and endolysosomes. BECN1 also promotes the targeting of a smaller fraction of internalized APP to LC3-positive phagophores, suggesting a role for BECN1-dependent PM macroautophagy in APP degradation. Furthermore, BECN1 facilitates lysosomal degradation of surface APP and reduces the secretion of APP metabolites (soluble ectodomains, sAPP). The association between APP and BECN1 is dependent on the evolutionarily conserved domain (ECD) of BECN1 (amino acids 267-337). Deletion of a BECN1 ECD subregion (amino acids 285-299) did not impair BECN1- PIK3C3 interaction, PtdIns3K function or macroautophagy, but was sufficient to impair the APP-BECN1 interaction and BECN1's effects on surface APP internalization and degradation, resulting in increased secretion of sAPPs. Interestingly, both the BECN1-APP association and BECN1-dependent APP endocytosis and degradative trafficking were negatively regulated by active AKT. Our results further implicate phosphorylation of the BECN1 Ser295 residue in the inhibition of APP degradation by AKT. Our studies reveal a novel function for BECN1 in the sorting of a plasma membrane protein for endolysosomal and macroautophagic degradation.

  7. Evidence supporting the role of calpain in the α-processing of amyloidprecursor protein.

    Science.gov (United States)

    Nguyen, Huey T; Sawmiller, Darrell R; Wu, Qi; Maleski, Jerome J; Chen, Ming

    2012-04-13

    Amyloid plaques are a hallmark of the aging and senile dementia brains, yet their mechanism of origins has remained elusive. A central issue is the regulatory mechanism and identity of α-secretase, a protease responsible for α-processing of amyloidprecursor protein (APP). A remarkable feature of this enzyme is its high sensitivity to a wide range of cellular stimulators, many of which are agonists for Ca(2+) signaling. This feature, together with previous work in our laboratory, has suggested that calpain, a Ca(2+)-dependent protease, plays a key role in APP α-processing. In this study we report that overexpression of the μ-calpain gene in HEK293 cells resulted in a 2.7-fold increase of the protein levels. Measurements of intracellular calpain enzymatic activity revealed that the calpain overexpressing cells displayed a prominent elevation of the activity compared to wild-type cells. When the cells were stimulated by nicotine, glutamate or phorbol 12,13-dibutylester, the activity increase was even more remarkable and sensitive to calpeptin, a calpain inhibitor. Meanwhile, APP secretion from the calpain overexpressing cells was robustly increased under both resting and stimulated conditions over wild-type cells. Furthermore, cell surface biotinylation experiments showed that μ-calpain was clearly detected among the cell surface proteins. These data together support our view that calpain should be a reasonable candidate for α-secretase for further study. This model is discussed with an interesting fact that three other deposited proteins (tau, spectrin and crystalline) are also the known substrates of calpain. Finally we discuss some current misconceptions in senile dementia research.

  8. Statins reduce amyloid β-peptide production by modulating amyloid precursor protein maturation and phosphorylation through a cholesterol-independent mechanism in cultured neurons.

    Science.gov (United States)

    Hosaka, Ai; Araki, Wataru; Oda, Akiko; Tomidokoro, Yasushi; Tamaoka, Akira

    2013-03-01

    Statins, 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, have been reported to attenuate amyloid-β peptide (Aβ) production in various cellular models. However, the mechanisms by which statins affect neuronal Aβ production have not yet been clarified. Here, we investigated this issue in rat primary cortical neurons using two statins, pitavastatin (PV) and atorvastatin (AV). Treatment of neurons with 0.2-2.5 μM PV or AV for 4 days induced a concentration- and time-dependent reduction in the secretion of both Aβ40 and Aβ42. Moreover, Western blot analyses of cell lysates showed that treatment with PV or AV significantly reduced expression levels of the mature form of amyloid precursor protein (APP) and Thr668-phosphorylated APP (P-APP), but not immature form of APP; the decreases in P-APP levels were more notable than those of mature APP levels. The statin treatment did not alter expression of BACE1 (β-site APP-cleaving enzyme 1) or γ-secretase complex proteins (presenilin 1, nicastrin, APH-1, and PEN-2). In neurons overexpressing APP via recombinant adenoviruses, PV or AV similarly reduced Aβ secretion and the levels of mature APP and P-APP. Statins also markedly reduced cellular cholesterol content in neurons in a concentration-dependent manner. Co-treatment with mevalonate reversed the statin-induced decreases in Aβ secretion and mature APP and P-APP levels, whereas co-treatment with cholesterol did not, despite recovery of cellular cholesterol levels. Finally, cell-surface biotinylation experiments revealed that both statins significantly reduced the levels of cell-surface P-APP without changing those of cell surface mature APP. These results suggest that statins reduce Aβ production by selectively modulating APP maturation and phosphorylation through a mechanism independent of cholesterol reduction in cultured neurons.

  9. Model Hirano bodies protect against tau-independent and tau-dependent cell death initiated by the amyloid precursor protein intracellular domain.

    Directory of Open Access Journals (Sweden)

    Matthew Furgerson

    Full Text Available The main pathological hallmarks of Alzheimer's disease are amyloid-beta plaques and neurofibrillary tangles, which are primarily composed of amyloid precursor protein (APP and tau, respectively. These proteins and their role in the mechanism of neurodegeneration have been extensively studied. Hirano bodies are a frequently occurring pathology in Alzheimer's disease as well as other neurodegenerative diseases. However, the physiological role of Hirano bodies in neurodegenerative diseases has yet to be determined. We have established cell culture models to study the role of Hirano bodies in amyloid precursor protein and tau-induced cell death mechanisms. Exogenous expression of APP and either of its c-terminal fragments c31 or Amyloid Precursor Protein Intracellular Domain c58 (AICDc58 enhance cell death. The presence of tau is not required for this enhanced cell death. However, the addition of a hyperphosphorylated tau mimic 352PHPtau significantly increases cell death in the presence of both APP and c31 or AICDc58 alone. The mechanism of cell death induced by APP and its c-terminal fragments and tau was investigated. Fe65, Tip60, p53, and caspases play a role in tau-independent and tau-dependent cell death. In addition, apoptosis was determined to contribute to cell death. The presence of model Hirano bodies protected against cell death, indicating Hirano bodies may play a protective role in neurodegeneration.

  10. Continuation of exercise is necessary to inhibit high fat diet-induced β-amyloid deposition and memory deficit in amyloid precursor protein transgenic mice.

    Science.gov (United States)

    Maesako, Masato; Uemura, Kengo; Iwata, Ayana; Kubota, Masakazu; Watanabe, Kiwamu; Uemura, Maiko; Noda, Yasuha; Asada-Utsugi, Megumi; Kihara, Takeshi; Takahashi, Ryosuke; Shimohama, Shun; Kinoshita, Ayae

    2013-01-01

    High fat diet (HFD) is prevalent in many modern societies and HFD-induced metabolic condition is a growing concern worldwide. It has been previously reported that HFD clearly worsens cognitive function in amyloid precursor protein (APP) transgenic mice. On the other hand, we have demonstrated that voluntary exercise in an enriched environment is an effective intervention to rescue HFD-induced β-amyloid (Aβ) deposition and memory deficit. However, it had been unclear whether consumption of HFD after exercising abolished the beneficial effect of exercise on the inhibition of Alzheimer's disease (AD) pathology. To examine this question, we exposed wild type (WT) and APP mice fed with HFD to exercise conditions at different time periods. In our previous experiment, we gave HFD to mice for 20 weeks and subjected them to exercise during weeks 10-20. In the present study, mice were subjected to exercise conditions during weeks 0-10 or weeks 5-15 while being on HFD. Interestingly, we found that the effect of exercise during weeks 0-10 or weeks 5-15 on memory function was not abolished in WT mice even if they kept having HFD after finishing exercise. However, in APP transgenic mice, HFD clearly disrupted the effect of exercise during weeks 0-10 or weeks 5-15 on memory function. Importantly, we observed that the level of Aβ oligomer was significantly elevated in the APP mice that exercised during weeks 0-10: this might have been caused by the up-regulation of Aβ production. These results provide solid evidence that continuation of exercise is necessary to rescue HFD-induced aggravation of cognitive decline in the pathological setting of AD.

  11. Continuation of exercise is necessary to inhibit high fat diet-induced β-amyloid deposition and memory deficit in amyloid precursor protein transgenic mice.

    Directory of Open Access Journals (Sweden)

    Masato Maesako

    Full Text Available High fat diet (HFD is prevalent in many modern societies and HFD-induced metabolic condition is a growing concern worldwide. It has been previously reported that HFD clearly worsens cognitive function in amyloid precursor protein (APP transgenic mice. On the other hand, we have demonstrated that voluntary exercise in an enriched environment is an effective intervention to rescue HFD-induced β-amyloid (Aβ deposition and memory deficit. However, it had been unclear whether consumption of HFD after exercising abolished the beneficial effect of exercise on the inhibition of Alzheimer's disease (AD pathology. To examine this question, we exposed wild type (WT and APP mice fed with HFD to exercise conditions at different time periods. In our previous experiment, we gave HFD to mice for 20 weeks and subjected them to exercise during weeks 10-20. In the present study, mice were subjected to exercise conditions during weeks 0-10 or weeks 5-15 while being on HFD. Interestingly, we found that the effect of exercise during weeks 0-10 or weeks 5-15 on memory function was not abolished in WT mice even if they kept having HFD after finishing exercise. However, in APP transgenic mice, HFD clearly disrupted the effect of exercise during weeks 0-10 or weeks 5-15 on memory function. Importantly, we observed that the level of Aβ oligomer was significantly elevated in the APP mice that exercised during weeks 0-10: this might have been caused by the up-regulation of Aβ production. These results provide solid evidence that continuation of exercise is necessary to rescue HFD-induced aggravation of cognitive decline in the pathological setting of AD.

  12. Transcriptional regulation of human FE65, a ligand of Alzheimer's disease amyloid precursor protein, by Sp1.

    LENUS (Irish Health Repository)

    Yu, Hoi-Tin

    2010-03-01

    FE65 is a neuronal-enriched adaptor protein that binds to the Alzheimer\\'s disease amyloid precursor protein (APP). FE65 forms a transcriptionally active complex with the APP intracellular domain (AICD). The precise gene targets for this complex are unclear but several Alzheimer\\'s disease-linked genes have been proposed. Additionally, evidence suggests that FE65 influences APP metabolism. The mechanism by which FE65 expression is regulated is as yet unknown. To gain insight into the regulatory mechanism, we cloned a 1.6 kb fragment upstream of the human FE65 gene and found that it possesses particularly strong promoter activity in neurones. To delineate essential regions in the human FE65 promoter, a series of deletion mutants were generated. The minimal FE65 promoter was located between -100 and +5, which contains a functional Sp1 site. Overexpression of the transcription factor Sp1 potentiates the FE65 promoter activity. Conversely, suppression of the FE65 promoter was observed in cells either treated with an Sp1 inhibitor or in which Sp1 was knocked down. Furthermore, reduced levels of Sp1 resulted in downregulation of endogenous FE65 mRNA and protein. These findings reveal that Sp1 plays a crucial role in transcriptional control of the human FE65 gene.

  13. CHIP stabilizes amyloid precursor protein via proteasomal degradation and p53-mediated trans-repression of β-secretase.

    Science.gov (United States)

    Singh, Amir Kumar; Pati, Uttam

    2015-08-01

    In patient with Alzheimer's disease (AD), deposition of amyloid-beta Aβ, a proteolytic cleavage of amyloid precursor protein (APP) by β-secretase/BACE1, forms senile plaque in the brain. BACE1 activation is caused due to oxidative stresses and dysfunction of ubiquitin-proteasome system (UPS), which is linked to p53 inactivation. As partial suppression of BACE1 attenuates Aβ generation and AD-related pathology, it might be an ideal target for AD treatment. We have shown that both in neurons and in HEK-APP cells, BACE1 is a new substrate of E3-ligase CHIP and an inverse relation exists between CHIP and BACE1 level. CHIP inhibits ectopic BACE1 level by promoting its ubiquitination and proteasomal degradation, thus reducing APP processing; it stabilizes APP in neurons, thus reducing Aβ. CHIP(U) (box) domain physically interacts with BACE1; however, both U-box and TPR domain are essential for ubiquitination and degradation of BACE1. Further, BACE1 is a downstream target of p53 and overexpression of p53 decreases BACE1 level. In HEK-APP cells, CHIP is shown to negatively regulate BACE1 promoter through stabilization of p53's DNA-binding conformation and its binding upon 5' UTR element (+127 to +150). We have thus discovered that CHIP regulates p53-mediated trans-repression of BACE1 at both transcriptional and post-translational level. We propose that a CHIP-BACE1-p53 feedback loop might control APP stabilization, which could further be utilized for new therapeutic intervention in AD.

  14. Enzyme specificity of proteinase inhibitor region in amyloid precursor protein of Alzheimer's disease: different properties compared with protease nexin I.

    Science.gov (United States)

    Kitaguchi, N; Takahashi, Y; Oishi, K; Shiojiri, S; Tokushima, Y; Utsunomiya, T; Ito, H

    1990-03-29

    Senile plaques, often surrounded by abnormally grown neurites, are characteristic of Alzheimer's diseased brain. The core of the plaque is mainly composed of amyloid beta protein (beta-AP), two of whose three precursors (APP) have serine proteinase inhibitor regions (APPI). APPI derivatives containing 60, 72 or 88 amino-acid fragments (APPI-60, APPI-72 and APPI-88, respectively) of the longest APP were produced in COS-1 cell culture medium, with the APPI cDNA ligated to the signal sequence of tissue plasminogen activator. The secreted APPIs were purified by sequential acetone precipitation followed by affinity chromatography using immobilized trypsin. These three APPIs and O-glycosylation-site-mutated APPI showed similar inhibitory activity against trypsin, chymotrypsin and plasmin. The purified APPI-72 was found to inhibit trypsin (Ki = 1.1 x 10(-10) M) and chymotrypsin (Ki = 5.8 x 10(-9) M) most strongly, and to inhibit leukocyte elastase (Ki = 7.9 x 10(-7) M) and several blood coagulation proteinases (Ki = 0.46-12 x 10(-7) M), but not urokinase or thrombin. The observed inhibition pattern was quite different from that of protease nexin I, one of serine proteinase inhibitors possessing neurite outgrowth activity. This suggests that the physiological roles of APPI are different from those of protease nexin I, and that APPI could not cause aberrant growth of neurite into the plaque. The presence of APPI having strong inhibitory activity in the brain might lead to the formation of amyloid deposits by preventing complete degradation of APPs.

  15. Soluble amyloid precursor protein alpha (sAPPα) inhibits tau phosphorylation through modulation of GSK3β signaling pathway

    Science.gov (United States)

    Deng, Juan; Habib, Ahsan; Obregon, Demian F.; Barger, Steven W.; Giunta, Brian; Wang, Yan-Jiang; Hou, Huayan; Sawmiller, Darrell; Tan, Jun

    2015-01-01

    We recently found that sAPPα decreases Aβ generation by directly associating with β-site amyloid precursor protein (APP) converting enzyme 1 (BACE1), thereby modulating APP processing. Because inhibition of BACE1 decreases GSK3β-mediated Alzheimer’s disease (AD)-like tau phosphorylation in AD patient-derived neurons, we determined whether sAPPα also reduces GSK3β-mediated tau phosphorylation. We initially found increased levels of inhibitory phosphorylation of GSK3β in primary neurons from sAPPα over-expressing mice. Further, recombinant human sAPPα evoked the same phenomenon in SH-SY5Y cells. Further, in SH-SY5Y cells overexpressing BACE1, and HeLa cells overexpressing human tau, sAPPα reduced GSK3β activity and tau phosphorylation. Importantly, the reductions in GSK3β activity and tau phosphorylation elicited by sAPPα were prevented by BACE1 but not γ-secretase inhibition. In accord, AD mice overexpressing human sAPPα had less GSK3β activity and tau phosphorylation compared with controls. These results implicate a direct relationship between APP β-processing and GSK3β-mediated tau phosphorylation and further define the central role of sAPPα in APP autoregulation and AD pathogenesis. PMID:26342176

  16. Amyloid precursor protein is required for normal function of the rod and cone pathways in the mouse retina.

    Directory of Open Access Journals (Sweden)

    Tracy Ho

    Full Text Available Amyloid precursor protein (APP is a transmembrane glycoprotein frequently studied for its role in Alzheimer's disease. Our recent study in APP knockout (KO mice identified an important role for APP in modulating normal neuronal development in the retina. However the role APP plays in the adult retina and whether it is required for vision is unknown. In this study we evaluated the role of APP in retinal function and morphology comparing adult wildtype (WT and APP-KO mice. APP was expressed on neuronal cells of the inner retina, including horizontal, cone bipolar, amacrine and ganglion cells in WT mice. The function of the retina was assessed using the electroretinogram and although the rod photoreceptor responses were similar in APP-KO and WT mice, the post-photoreceptor, inner retinal responses of both the rod and cone pathways were reduced in APP-KO mice. These changes in inner retinal function did not translate to a substantial change in visual acuity as assessed using the optokinetic response or to changes in the gross cellular structure of the retina. These findings indicate that APP is not required for basic visual function, but that it is involved in modulating inner retinal circuitry.

  17. Peripheral biomarkers in Autism: secreted amyloid precursor protein-alpha as a probable key player in early diagnosis.

    Science.gov (United States)

    Bailey, Antoinette R; Giunta, Brian N; Obregon, Demian; Nikolic, William V; Tian, Jun; Sanberg, Cyndy D; Sutton, Danielle T; Tan, Jun

    2008-01-01

    Autism is a pervasive developmental disorder characterized by impairments in socialization and communication. There is currently no single molecular marker or laboratory tool capable of diagnosing autism at an early age. The purpose of this study is to explore the plausible use of peripheral biomarkers in the early diagnosis of autism via a sensitive ELISA. Here, we measured plasma secreted amyloid precursor protein alpha (sAPP-alpha) levels in autistic and aged-matched control blood samples and found a significantly increased level of sAPP-alpha in 60% of the known autistic children. We then tested 150 human umbilical cord blood (HUCB) samples and found significantly elevated levels of plasma sAPP-alpha in 10 of 150 samples. As an additional confirmatory measure, we performed Western blot analysis on these samples which consistently showed increased sAPP-alpha levels in autistic children and 10 of 150 HUCB samples; suggesting a group of autistic patients which could be identified in early childhood by levels of sAPP-alpha. While there is need for further studies of this concept, the measurement of sAPP-alpha levels in serum and human umbilical cord blood by ELISA is a potential tool for early diagnosis of autism.

  18. Amyloid precursor protein modulates Nav1.6 sodium channel currents through a Go-coupled JNK pathway

    Science.gov (United States)

    Li, Shao; Wang, Xi; Ma, Quan-Hong; Yang, Wu-lin; Zhang, Xiao-Gang; Dawe, Gavin S.; Xiao, Zhi-Cheng

    2016-01-01

    Amyloid precursor protein (APP), commonly associated with Alzheimer’s disease, also marks axonal degeneration. In the recent studies, we demonstrated that APP aggregated at nodes of Ranvier (NORs) in myelinated central nervous system (CNS) axons and interacted with Nav1.6. However, the physiological function of APP remains unknown. In this study, we described reduced sodium current densities in APP knockout hippocampal neurons. Coexpression of APP or its intracellular domains containing a VTPEER motif with Nav1.6 sodium channels in Xenopus oocytes resulted in an increase in peak sodium currents, which was enhanced by constitutively active Go mutant and blocked by a dominant negative mutant. JNK and CDK5 inhibitor attenuated increases in Nav1.6 sodium currents induced by overexpression of APP. Nav1.6 sodium currents were increased by APPT668E (mutant Thr to Glu) and decreased by T668A (mutant Thr to ALa) mutant, respectively. The cell surface expression of Nav1.6 sodium channels in the white matter of spinal cord and the spinal conduction velocity is decreased in APP, p35 and JNK3 knockout mice. Therefore, APP modulates Nav1.6 sodium channels through a Go-coupled JNK pathway, which is dependent on phosphorylation of APP at Thr668. PMID:28008944

  19. Genomic mosaicism with increased amyloid precursor protein (APP) gene copy number in single neurons from sporadic Alzheimer's disease brains.

    Science.gov (United States)

    Bushman, Diane M; Kaeser, Gwendolyn E; Siddoway, Benjamin; Westra, Jurgen W; Rivera, Richard R; Rehen, Stevens K; Yung, Yun C; Chun, Jerold

    2015-02-04

    Previous reports have shown that individual neurons of the brain can display somatic genomic mosaicism of unknown function. In this study, we report altered genomic mosaicism in single, sporadic Alzheimer's disease (AD) neurons characterized by increases in DNA content and amyloid precursor protein (APP) gene copy number. AD cortical nuclei displayed large variability with average DNA content increases of ~8% over non-diseased controls that were unrelated to trisomy 21. Two independent single-cell copy number analyses identified amplifications at the APP locus. The use of single-cell qPCR identified up to 12 copies of APP in sampled neurons. Peptide nucleic acid (PNA) probes targeting APP, combined with super-resolution microscopy detected primarily single fluorescent signals of variable intensity that paralleled single-cell qPCR analyses. These data identify somatic genomic changes in single neurons, affecting known and unknown loci, which are increased in sporadic AD, and further indicate functionality for genomic mosaicism in the CNS.

  20. Effects of ethanol on aggregation, serotonin release, and amyloid precursor protein processing in rat and human platelets.

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    Ehrlich, Daniela; Humpel, Christian

    2014-01-01

    It is known that oxidative stress leads to amyloid precursor protein (APP) dysregulation in platelets. Ethanol (EtOH) is a vascular risk factor and induces oxidative stress. The aim of the present study was thus to investigate whether EtOH affects APP processing in rat and human platelets. Platelets were exposed to 50 mM EtOH with and without 2 mM calcium-chloride (CaCl₂) for 20 or 180 minutes at 37°C. Platelet aggregation, serotonin release and APP isoforms 130 and 106/110 kDa were analyzed. As a control, 100 mM H₂O₂ was tested in rat platelets. Our data show that EtOH alone did not affect any of the analyzed parameters, whereas CaCl₂ significantly increased aggregation of rat and human platelets. In addition, CaCl₂ alone enhanced serotonin release in rat platelets. EtOH counteracted CaCl₂-induced aggregation and serotonin release. In the presence of CaCl₂, EtOH reduced the 130 kDa APP isoform in rat and human platelets. In conclusion, this study shows that in the presence of CaCl₂, EtOH affects the platelet function and APP processing in rat and human platelets.

  1. Two different immunostaining patterns of beta-amyloid precursor protein (APP) may distinguish traumatic from nontraumatic axonal injury.

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    Hayashi, Takahito; Ago, Kazutoshi; Nakamae, Takuma; Higo, Eri; Ogata, Mamoru

    2015-09-01

    Immunostaining for beta-amyloid precursor protein (APP) is recognized as an effective tool for detecting traumatic axonal injury, but it also detects axonal injury due to ischemic or other metabolic causes. Previously, we reported two different patterns of APP staining: labeled axons oriented along with white matter bundles (pattern 1) and labeled axons scattered irregularly (pattern 2) (Hayashi et al. (Leg Med (Tokyo) 11:S171-173, 2009). In this study, we investigated whether these two patterns are consistent with patterns of trauma and hypoxic brain damage, respectively. Sections of the corpus callosum from 44 cases of blunt head injury and equivalent control tissue were immunostained for APP. APP was detected in injured axons such as axonal bulbs and varicose axons in 24 of the 44 cases of head injuries that also survived for three or more hours after injury. In 21 of the 24 APP-positive cases, pattern 1 alone was observed in 14 cases, pattern 2 alone was not observed in any cases, and both patterns 1 and 2 were detected in 7 cases. APP-labeled injured axons were detected in 3 of the 44 control cases, all of which were pattern 2. These results suggest that pattern 1 indicates traumatic axonal injury, while pattern 2 results from hypoxic insult. These patterns may be useful to differentiate between traumatic and nontraumatic axonal injuries.

  2. Conformational changes induced by the A21G Flemish mutation in the amyloid precursor protein lead to increased Aβ production.

    Science.gov (United States)

    Tang, Tzu-Chun; Hu, Yi; Kienlen-Campard, Pascal; El Haylani, Laetitia; Decock, Marie; Van Hees, Joanne; Fu, Ziao; Octave, Jean-Noel; Constantinescu, Stefan N; Smith, Steven O

    2014-03-04

    Proteolysis of the β C-terminal fragment (β-CTF) of the amyloid precursor protein generates the Aβ peptides associated with Alzheimer's disease. Familial mutations in the β-CTF, such as the A21G Flemish mutation, can increase Aβ secretion. We establish how the Flemish mutation alters the structure of C55, the first 55 residues of the β-CTF, using FTIR and solid-state NMR spectroscopy. We show that the A21G mutation reduces β sheet structure of C55 from Leu17 to Ala21, an inhibitory region near the site of the mutation, and increases α-helical structure from Gly25 to Gly29, in a region near the membrane surface and thought to interact with cholesterol. Cholesterol also increases Aβ peptide secretion, and we show that the incorporation of cholesterol into model membranes enhances the structural changes induced by the Flemish mutant, suggesting a common link between familial mutations and the cellular environment.

  3. Compound Danshen tablets downregulate amyloid protein precursor mRNA expression in a transgenic cell model of Alzheimer's disease Effects and a comparison with donepezil

    Institute of Scientific and Technical Information of China (English)

    Ren'an Qin; Desheng Zhou; Jiajun Wang; Hua Hu; Yang Yang; Xiaoxuan Yao; Xiaopeng Sun

    2012-01-01

    After gene mutation, the pcDNA3.1/APP595/596 plasmid was transfected into HEK293 cells to establish a cell model of Alzheimer’s disease. The cell model was treated with donepezil or compound Danshen tablets after culture for 72 hours. Reverse transcription-PCR showed that the mRNA expression of amyloid protein precursor decreased in all groups following culture for 24 hours, and that there was no significant difference in the amount of decrease between donepezil and compound Danshen tablets. Our results suggest that compound Danshen tablets can reduce expression of the mRNA for amyloid protein precursor in a transgenic cell model of Alzheimer’s disease, with similar effects to donepezil.

  4. Cerebrospinal fluid levels of amyloid precursor protein are associated with ventricular size in post-hemorrhagic hydrocephalus of prematurity.

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    Diego M Morales

    Full Text Available Neurological outcomes of preterm infants with post-hemorrhagic hydrocephalus (PHH remain among the worst in infancy, yet there remain few instruments to inform the treatment of PHH. We previously observed PHH-associated elevations in cerebrospinal fluid (CSF amyloid precursor protein (APP, neural cell adhesion molecule-L1 (L1CAM, neural cell adhesion molecule-1 (NCAM-1, and other protein mediators of neurodevelopment.The objective of this study was to examine the association of CSF APP, L1CAM, and NCAM-1 with ventricular size as an early step toward developing CSF markers of PHH.CSF levels of APP, L1CAM, NCAM-1, and total protein (TP were measured in 12 preterm infants undergoing PHH treatment. Ventricular size was determined using cranial ultrasounds. The relationships between CSF APP, L1CAM, and NCAM-1, occipitofrontal circumference (OFC, volume of CSF removed, and ventricular size were examined using correlation and regression analyses.CSF levels of APP, L1CAM, and NCAM-1 but not TP paralleled treatment-related changes in ventricular size. CSF APP demonstrated the strongest association with ventricular size, estimated by frontal-occipital horn ratio (FOR (Pearson R = 0.76, p = 0.004, followed by NCAM-1 (R = 0.66, p = 0.02 and L1CAM (R = 0.57,p = 0.055. TP was not correlated with FOR (R = 0.02, p = 0.95.Herein, we report the novel observation that CSF APP shows a robust association with ventricular size in preterm infants treated for PHH. The results from this study suggest that CSF APP and related proteins at once hold promise as biomarkers of PHH and provide insight into the neurological consequences of PHH in the preterm infant.

  5. Quantification of gamma-secretase modulation differentiates inhibitor compound selectivity between two substrates Notch and amyloid precursor protein

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    Yang Ting

    2008-11-01

    Full Text Available Abstract Background Deposition of amyloidprotein (Aβ is a major pathological hallmark of Alzheimer's disease (AD. Aβ is generated from γ-secretase cleavage of amyloid precursor protein (APP. In addition to APP, γ-secretase also cleaves other type I integral membrane proteins, including the Notch receptor, a key molecule involved in embryonic development. Results To explore selective γ-secretase inhibitors, a combination of five methods was used to systematically determine these inhibitors' profiles on the γ-secretase cleavage of APP and Notch. When two potent γ-secretase inhibitors, compound E (cpd E and DAPT, were used in a conventional in vitro γ-secretase activity assay, cpd E completely blocked Aβ generation from the cleavage of substrate APP C100, but only had a minor effect on Notch cleavage and NICD generation. Next, cpd E and DAPT were applied to HEK293 cells expressing a truncated Notch substrate NotchΔE. Both cpd E and DAPT were more potent in blocking Aβ generation than NICD generation. Third, a reporter construct was created that carried the NICD targeting promoter with three Su(H binding sequences followed by the luciferase gene. We found that the inhibition of NICD generation by cpd E and DAPT was consistent with the reduced expression of luciferase gene driven by this Notch targeting promoter. Fourth, levels of "Notch-Aβ-like" (Nβ* peptide derived from two previously reported chimeric APP with its transmembrane domain or the juxtamembrane portion replaced by the Notch sequence were quantified. Measurement of Nβ* peptides by ELISA confirmed that EC50's of cpd E were much higher for Nβ* than Aβ. Finally, the expression levels of Notch target gene her6 in cpd E or DAPT-treated zebrafish were correlated with the degree of tail curvature due to defective somitogenesis, a well characterized Notch phenotype in zebrafish. Conclusion Our ELISA-based quantification of Aβ and Nβ* in combination with the test in

  6. Characterization of amyloidprecursor protein intracellular domain-associated transcriptional complexes in SH-SY5Y neurocytes

    Institute of Scientific and Technical Information of China (English)

    Wulin Yang; Amy Yong Chen Lau; Shuizhong Luo; Qian Zhu3; Li Lu

    2012-01-01

    [Objective] Alzheimer's disease (AD) is one of the major disorders worldwide.Recent research suggests that the amyloidprecursor protein intracellular domain (AICD) is a potential contributor to AD development and progression.The small AICD is rapidly degraded after processing from the full-length protein.The present study aimed to apply a highly efficient biotinylation approach in vitro to study AICD-associated complexes in neurocytes.[Methods] By coexpressing Escherichia coli biotin ligase with biotinyl-tagged AICD in the SH-SY5Y neuronal cell line,the effects of AICD overexpression on cell proliferation and apoptosis were analyzed.Besides,AICD-associated nuclear transcriptional complexes were purified and then examined by mass spectrometry.[Results] Our data showed that AICD overexpression not only affected cell proliferation but also led to apoptosis in differentiated SH-SY5Y cells.Moreover,biotinylation allowed single-step purification of biotinylated AICD-associated complexes from total nuclear extract via high-affinity biotin-streptavidin binding.Following this by mass spectrometry,we identified physically associated proteins,some reported previously and other novel binding partners,CUX1 and SPT5.[Conclusion]Based on these [Results],a map of theAICD-associated nuclear interactome was depicted.Specifically,AICD can activate CUXI transcriptional activity,which may be associated with AICD-dependent neuronal cell death.This work helps to understand the AICD-associated biologicalevents in AD progression and provides novel insights into the development of AD.

  7. Glucocorticoids increase impairments in learning and memory due to elevated amyloid precursor protein expression and neuronal apoptosis in 12-month old mice.

    Science.gov (United States)

    Li, Wei-Zu; Li, Wei-Ping; Yao, Yu-You; Zhang, Wen; Yin, Yan-Yan; Wu, Guo-Cui; Gong, Hui-Ling

    2010-02-25

    Alzheimer's disease is a chronic neurodegenerative disorder marked by a progressive loss of memory and cognitive function. Stress level glucocorticoids are correlated with dementia progression in patients with Alzheimer's disease. In this study, twelve month old male mice were chronically treated for 21 days with stress-level dexamethasone (5mg/kg). We investigated the pathological consequences of dexamethasone administration on learning and memory impairments, amyloid precursor protein processing and neuronal cell apoptosis in 12-month old male mice. Our results indicate that dexamethasone can induce learning and memory impairments, neuronal cell apoptosis, and mRNA levels of the amyloid precursor protein, beta-secretase and caspase-3 are selectively increased after dexamethasone administration. Immunohistochemistry demonstrated that amyloid precursor protein, caspase-3 and cytochrome c in the cortex and CA1, CA3 regions of the hippocampus are significantly increased in 12-month old male mice. Furthermore, dexamethasone treatment induced cortex and hippocampus neuron apoptosis as well as increasing the activity of caspase-9 and caspase-3. These findings suggest that high levels of glucocorticoids, found in Alzheimer's disease, are not merely a consequence of the disease process but rather play a central role in the development and progression of Alzheimer's disease. Stress management or pharmacological reduction of glucocorticoids warrant additional consideration of the regimen used in Alzheimer's disease therapies.

  8. Neuroanatomical localization and quantification of amyloid precursor protein mRNA by in situ hybridization in the brains of normal, aneuploid, and lesioned mice

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    Bendotti, C.; Forloni, G.L.; Morgan, R.A.; O' Hara, B.F.; Oster-Granite, M.L.; Reeves, R.H.; Gearhart, J.D.; Coyle, J.T. (Johns Hopkins Univ. School of Medicine, Baltimore, MD (USA))

    1988-05-01

    Amyloid precursor protein mRNA was localized in frozen sections from normal and experimentally lesioned adult mouse brain and from normal and aneuploid fetal mouse brain by in situ hybridization with a {sup 35}S-labeled mouse cDNA probe. The highest levels of hybridization in adult brain were associated with neurons, primarily in telencephalic structures. The dense labeling associated with hippocampal pyramidal cells was reduced significantly when the cells were eliminated by injection of the neurotoxin ibotenic acid but was not affected when electrolytic lesions were placed in the medial septum. Since the gene encoding amyloid precursor protein has been localized to mouse chromosome 16, the authors also examined the expression of this gene in the brains of mouse embryos with trisomy 16 and trisomy 19 at 15 days of gestation. RNA gel blot analysis and in situ hybridization showed a marked increase in amyloid precursor protein mRNA in the trisomy 16 mouse head and brain when compared with euploid littermates or with trisomy 19 mice.

  9. Dual-specificity phosphatase 26 (DUSP26) stimulates Aβ42 generation by promoting amyloid precursor protein axonal transport during hypoxia.

    Science.gov (United States)

    Jung, Sunmin; Nah, Jihoon; Han, Jonghee; Choi, Seon-Guk; Kim, Hyunjoo; Park, Jaesang; Pyo, Ha-Kyung; Jung, Yong-Keun

    2016-06-01

    Amyloid beta peptide (Aβ) is a pathological hallmark of Alzheimer's disease (AD) and is generated through the sequential cleavage of amyloid precursor protein (APP) by β- and γ-secretases. Hypoxia is a known risk factor for AD and stimulates Aβ generation by γ-secretase; however, the underlying mechanisms remain unclear. In this study, we showed that dual-specificity phosphatase 26 (DUSP26) regulates Aβ generation through changes in subcellular localization of the γ-secretase complex and its substrate C99 under hypoxic conditions. DUSP26 was identified as a novel γ-secretase regulator from a genome-wide functional screen using a cDNA expression library. The phosphatase activity of DUSP26 was required for the increase in Aβ42 generation through γ-secretase, but this regulation did not affect the amount of the γ-secretase complex. Interestingly, DUSP26 induced the accumulation of C99 in the axons by stimulating anterograde transport of C99-positive vesicles. Additionally, DUSP26 induced c-Jun N-terminal kinase (JNK) activation for APP processing and axonal transport of C99. Under hypoxic conditions, DUSP26 expression levels were elevated together with JNK activation, and treatment with JNK inhibitor SP600125, or the DUSP26 inhibitor NSC-87877, reduced hypoxia-induced Aβ generation by diminishing vesicle trafficking of C99 to the axons. Finally, we observed enhanced DUSP26 expression and JNK activation in the hippocampus of AD patients. Our results suggest that DUSP26 mediates hypoxia-induced Aβ generation through JNK activation, revealing a new regulator of γ-secretase-mediated APP processing under hypoxic conditions. We propose the role of phosphatase dual-specificity phosphatase 26 (DUSP26) in the selective regulation of Aβ42 production in neuronal cells under hypoxic stress. Induction of DUSP26 causes JNK-dependent shift in the subcellular localization of γ-secretase and C99 from the cell body to axons for Aβ42 generation. These findings provide a

  10. The Amyloid Precursor Protein (APP) Does Not Have a Ferroxidase Site in Its E2 Domain

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    Honarmand Ebrahimi, K.; Dienemann, C.; Hoefgens, S.; Than, M.E.; Hagedoorn, P.L.; Hagen, W.R.

    2013-01-01

    The ubiquitous 24-meric iron-storage protein ferritin and multicopper oxidases such as ceruloplasmin or hephaestin catalyze oxidation of Fe(II) to Fe(III), using molecular oxygen as oxidant. The ferroxidase activity of these proteins is essential for cellular iron homeostasis. It has been reported t

  11. A synthetic peptide with the putative iron binding motif of amyloid precursor protein (APP does not catalytically oxidize iron.

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    Kourosh Honarmand Ebrahimi

    Full Text Available The β-amyloid precursor protein (APP, which is a key player in Alzheimer's disease, was recently reported to possess an Fe(II binding site within its E2 domain which exhibits ferroxidase activity [Duce et al. 2010, Cell 142: 857]. The putative ligands of this site were compared to those in the ferroxidase site of ferritin. The activity was indirectly measured using transferrin, which scavenges the Fe(III product of the reaction. A 22-residue synthetic peptide, named FD1, with the putative ferroxidase site of APP, and the E2 domain of APP were each reported to exhibit 40% of the ferroxidase activity of APP and of ceruloplasmin. It was also claimed that the ferroxidase activity of APP is inhibited by Zn(II just as in ferritin. We measured the ferroxidase activity indirectly (i by the incorporation of the Fe(III product of the ferroxidase reaction into transferrin and directly (ii by monitoring consumption of the substrate molecular oxygen. The results with the FD1 peptide were compared to the established ferroxidase activities of human H-chain ferritin and of ceruloplasmin. For FD1 we observed no activity above the background of non-enzymatic Fe(II oxidation by molecular oxygen. Zn(II binds to transferrin and diminishes its Fe(III incorporation capacity and rate but it does not specifically bind to a putative ferroxidase site of FD1. Based on these results, and on comparison of the putative ligands of the ferroxidase site of APP with those of ferritin, we conclude that the previously reported results for ferroxidase activity of FD1 and - by implication - of APP should be re-evaluated.

  12. A synthetic peptide with the putative iron binding motif of amyloid precursor protein (APP) does not catalytically oxidize iron.

    Science.gov (United States)

    Ebrahimi, Kourosh Honarmand; Hagedoorn, Peter-Leon; Hagen, Wilfred R

    2012-01-01

    The β-amyloid precursor protein (APP), which is a key player in Alzheimer's disease, was recently reported to possess an Fe(II) binding site within its E2 domain which exhibits ferroxidase activity [Duce et al. 2010, Cell 142: 857]. The putative ligands of this site were compared to those in the ferroxidase site of ferritin. The activity was indirectly measured using transferrin, which scavenges the Fe(III) product of the reaction. A 22-residue synthetic peptide, named FD1, with the putative ferroxidase site of APP, and the E2 domain of APP were each reported to exhibit 40% of the ferroxidase activity of APP and of ceruloplasmin. It was also claimed that the ferroxidase activity of APP is inhibited by Zn(II) just as in ferritin. We measured the ferroxidase activity indirectly (i) by the incorporation of the Fe(III) product of the ferroxidase reaction into transferrin and directly (ii) by monitoring consumption of the substrate molecular oxygen. The results with the FD1 peptide were compared to the established ferroxidase activities of human H-chain ferritin and of ceruloplasmin. For FD1 we observed no activity above the background of non-enzymatic Fe(II) oxidation by molecular oxygen. Zn(II) binds to transferrin and diminishes its Fe(III) incorporation capacity and rate but it does not specifically bind to a putative ferroxidase site of FD1. Based on these results, and on comparison of the putative ligands of the ferroxidase site of APP with those of ferritin, we conclude that the previously reported results for ferroxidase activity of FD1 and - by implication - of APP should be re-evaluated.

  13. Structural basis for matrix metalloproteinase-2 (MMP-2)-selective inhibitory action of β-amyloid precursor protein-derived inhibitor.

    Science.gov (United States)

    Hashimoto, Hiroshi; Takeuchi, Tomoka; Komatsu, Kyoko; Miyazaki, Kaoru; Sato, Mamoru; Higashi, Shouichi

    2011-09-23

    Unlike other synthetic or physiological inhibitors for matrix metalloproteinases (MMPs), the β-amyloid precursor protein-derived inhibitory peptide (APP-IP) having an ISYGNDALMP sequence has a high selectivity toward MMP-2. Our previous study identified amino acid residues of MMP-2 essential for its selective inhibition by APP-IP and demonstrated that the N to C direction of the decapeptide inhibitor relative to the substrate-binding cleft of MMP-2 is opposite that of substrate. However, detailed interactions between the two molecules remained to be clarified. Here, we determined the crystal structure of the catalytic domain of MMP-2 in complex with APP-IP. We found that APP-IP in the complex is indeed embedded into the substrate-binding cleft of the catalytic domain in the N to C direction opposite that of substrate. With the crystal structure, it was first clarified that the aromatic side chain of Tyr(3) of the inhibitor is accommodated into the S1' pocket of the protease, and the carboxylate group of Asp(6) of APP-IP coordinates bidentately to the catalytic zinc of the enzyme. The Ala(7) to Pro(10) and Tyr(3) to Ile(1) strands of the inhibitor extend into the nonprime and the prime sides of the cleft, respectively. Therefore, the decapeptide inhibitor has long range contact with the substrate-binding cleft of the protease. This mode of interaction is probably essential for the high MMP-2 selectivity of the inhibitor because MMPs share a common architecture in the vicinity of the catalytic center, but whole structures of their substrate-binding clefts have sufficient variety for the inhibitor to distinguish MMP-2 from other MMPs.

  14. Characterization of the beta amyloid precursor protein-like gene in the central nervous system of the crab Chasmagnathus. Expression during memory consolidation

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    Fustiñana Maria

    2010-09-01

    Full Text Available Abstract Background Human β-amyloid, the main component in the neuritic plaques found in patients with Alzheimer's disease, is generated by cleavage of the β-amyloid precursor protein. Beyond the role in pathology, members of this protein family are synaptic proteins and have been associated with synaptogenesis, neuronal plasticity and memory, both in vertebrates and in invertebrates. Consolidation is necessary to convert a short-term labile memory to a long-term and stable form. During consolidation, gene expression and de novo protein synthesis are regulated in order to produce key proteins for the maintenance of plastic changes produced during the acquisition of new information. Results Here we partially cloned and sequenced the beta-amyloid precursor protein like gene homologue in the crab Chasmagnathus (cappl, showing a 37% of identity with the fruit fly Drosophila melanogaster homologue and 23% with Homo sapiens but with much higher degree of sequence similarity in certain regions. We observed a wide distribution of cappl mRNA in the nervous system as well as in muscle and gills. The protein localized in all tissues analyzed with the exception of muscle. Immunofluorescence revealed localization of cAPPL in associative and sensory brain areas. We studied gene and protein expression during long-term memory consolidation using a well characterized memory model: the context-signal associative memory in this crab species. mRNA levels varied at different time points during long-term memory consolidation and correlated with cAPPL protein levels Conclusions cAPPL mRNA and protein is widely distributed in the central nervous system of the crab and the time course of expression suggests a role of cAPPL during long-term memory formation.

  15. Using BAC transgenesis in zebrafish to identify regulatory sequences of the amyloid precursor protein gene in humans

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    Shakes Leighcraft A

    2012-09-01

    Full Text Available Abstract Background Non-coding DNA in and around the human Amyloid Precursor Protein (APP gene that is central to Alzheimer’s disease (AD shares little sequence similarity with that of appb in zebrafish. Identifying DNA domains regulating expression of the gene in such situations becomes a challenge. Taking advantage of the zebrafish system that allows rapid functional analyses of gene regulatory sequences, we previously showed that two discontinuous DNA domains in zebrafish appb are important for expression of the gene in neurons: an enhancer in intron 1 and sequences 28–31 kb upstream of the gene. Here we identify the putative transcription factor binding sites responsible for this distal cis-acting regulation, and use that information to identify a regulatory region of the human APP gene. Results Functional analyses of intron 1 enhancer mutations in enhancer-trap BACs expressed as transgenes in zebrafish identified putative binding sites of two known transcription factor proteins, E4BP4/ NFIL3 and Forkhead, to be required for expression of appb. A cluster of three E4BP4 sites at −31 kb is also shown to be essential for neuron-specific expression, suggesting that the dependence of expression on upstream sequences is mediated by these E4BP4 sites. E4BP4/ NFIL3 and XFD1 sites in the intron enhancer and E4BP4/ NFIL3 sites at −31 kb specifically and efficiently bind the corresponding zebrafish proteins in vitro. These sites are statistically over-represented in both the zebrafish appb and the human APP genes, although their locations are different. Remarkably, a cluster of four E4BP4 sites in intron 4 of human APP exists in actively transcribing chromatin in a human neuroblastoma cell-line, SHSY5Y, expressing APP as shown using chromatin immunoprecipitation (ChIP experiments. Thus although the two genes share little sequence conservation, they appear to share the same regulatory logic and are regulated by a similar set of transcription

  16. Effects of Amyloid Precursor Protein 17 Peptide on the Protection of Diabetic Encephalopathy and Improvement of Glycol Metabolism in the Diabetic Rat

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    Heng Meng

    2013-01-01

    Full Text Available Researchers have proposed that amyloid precursor protein 17 peptide (APP17 peptide, an active fragment of amyloid precursor protein (APP in the nervous system, has therapeutic effects on neurodegeneration. Diabetic encephalopathy (DE is a neurological disease caused by diabetes. Here we use multiple experimental approaches to investigate the effect of APP17 peptide on changes in learning behavior and glycol metabolism in rats. It was found that rats with DE treated by APP17 peptide showed reversed behavioral alternation. The [18F]-FDG-PET images and other results all showed that the APP17 peptide could promote glucose metabolism in the brain of the DE rat model. Meanwhile, the insulin signaling was markedly increased as shown by increased phosphorylation of Akt and enhanced GLUT4 activation. Compared with the DE group, the activities of SOD, GSH-Px, and CAT in the rat hippocampal gyrus were increased, while MDA decreased markedly in the DE + APP17 peptide group. No amyloid plaques in the cortex and the hippocampus were detected in either group, indicating that the experimental animals in the current study were not suffering from Alzheimer’s disease. These results indicate that APP17 peptide could be used to treat DE effectively.

  17. An Aberrant Phosphorylation of Amyloid Precursor Protein Tyrosine Regulates Its Trafficking and the Binding to the Clathrin Endocytic Complex in Neural Stem Cells of Alzheimer's Disease Patients

    Science.gov (United States)

    Poulsen, Ebbe T.; Iannuzzi, Filomena; Rasmussen, Helle F.; Maier, Thorsten J.; Enghild, Jan J.; Jørgensen, Arne L.; Matrone, Carmela

    2017-01-01

    Alzheimer's disease (AD) is the most common cause of dementia and is likely caused by defective amyloid precursor protein (APP) trafficking and processing in neurons leading to amyloid plaques containing the amyloid-β (Aβ) APP peptide byproducts. Understanding how APP is targeted to selected destinations inside neurons and identifying the mechanisms responsible for the generation of Aβ are thus the keys for the advancement of new therapies. We previously developed a mouse model with a mutation at tyrosine (Tyr) 682 in the C-terminus of APP. This residue is needed for APP to bind to the coating protein Clathrin and to the Clathrin adaptor protein AP2 as well as for the correct APP trafficking and sorting in neurons. By extending these findings to humans, we found that APP binding to Clathrin is decreased in neural stem cells from AD sufferers. Increased APP Tyr phosphorylation alters APP trafficking in AD neurons and it is associated to Fyn Tyr kinase activation. We show that compounds affecting Tyr kinase activity and counteracting defects in AD neurons can control APP location and compartmentalization. APP Tyr phosphorylation is thus a potential therapeutic target for AD.

  18. Amyloid precursor protein and growth-associated protein 43 expression in brain white matter and spinal cord tissues in a rat model of experimental autoimmune encephalomyelitis

    Institute of Scientific and Technical Information of China (English)

    Yizhou Wang; Shuang Kou; Jingcheng Tang; Ping Zhang; Qiuxia Zhang; Yan Liu; Qi Zheng; Hui Zhao; Lei Wang

    2011-01-01

    Studies have demonstrated that amyloid precursor protein (APP) expression increases in multiple sclerosis tissues during acutely and chronically active stages.To determine the relationship between axonal injury and regeneration in multiple sclerosis, an animal model of experimental autoimmune encephalomyelitis was induced using different doses of myelin basic protein peptide.APP and growth-associated protein 43 (GAP-43), which is considered a specific marker of neural regeneration, were assessed by western blot analysis.Expression of APP and GAP-43, as well as the correlation between these two proteins, in brain white matter and spinal cord tissues of experimental autoimmune encephalomyelitis rats at different pathological stages was analyzed.Results showed that APP and GAP-43 expression increased during the acute stage and decreased during remission, with a positive correlation between APP and GAP-43 expression in brain white matter and spinal cord tissues.These results suggest that APP and GAP-43 could provide nutritional and protective effects on damaged neurons.

  19. The histidine composition of the amyloid-β domain, but not the E1 copper binding domain, modulates β-secretase processing of amyloidprotein precursor in Alzheimer's disease.

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    Gough, Mallory; Blanthorn-Hazell, Sophee; Parkin, Edward T

    2015-01-01

    Amyloidprotein precursor (AβPP) proteolysis by β- and γ-secretases generates neurotoxic amyloid-β (Aβ)-peptides in Alzheimer's disease (AD). We have investigated the role of histidine residues within the extracellular E1 copper binding and Aβ domains of AβPP in its proteolysis. By stably expressing histidine to alanine AβPP mutant constructs in SH-SY5Y cells, we show that mutations in the E1 copper binding domain had no impact on α- or β-secretase processing. Mutation of histidine 14 within the Aβ-domain specifically down-regulated β-secretase processing without impacting on non-amyloidogenic proteolysis. Understanding how histidine 14 participates in AβPP proteolysis may reveal new intervention points for AD treatments.

  20. Interaction of the amyloid precursor protein-like protein 1 (APLP1) E2 domain with heparan sulfate involves two distinct binding modes

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    Dahms, Sven O., E-mail: sdahms@fli-leibniz.de [Leibniz Institute for Age Research (FLI), Beutenbergstrasse 11, 07745 Jena (Germany); Mayer, Magnus C. [Freie Universität Berlin, Thielallee 63, 14195 Berlin (Germany); Miltenyi Biotec GmbH, Robert-Koch-Strasse 1, 17166 Teterow (Germany); Roeser, Dirk [Leibniz Institute for Age Research (FLI), Beutenbergstrasse 11, 07745 Jena (Germany); Multhaup, Gerd [McGill University Montreal, Montreal, Quebec H3G 1Y6 (Canada); Than, Manuel E., E-mail: sdahms@fli-leibniz.de [Leibniz Institute for Age Research (FLI), Beutenbergstrasse 11, 07745 Jena (Germany)

    2015-03-01

    Two X-ray structures of APLP1 E2 with and without a heparin dodecasaccharide are presented, revealing two distinct binding modes of the protein to heparan sulfate. The data provide a mechanistic explanation of how APP-like proteins bind to heparan sulfates and how they specifically recognize nonreducing structures of heparan sulfates. Beyond the pathology of Alzheimer’s disease, the members of the amyloid precursor protein (APP) family are essential for neuronal development and cell homeostasis in mammals. APP and its paralogues APP-like protein 1 (APLP1) and APP-like protein 2 (APLP2) contain the highly conserved heparan sulfate (HS) binding domain E2, which effects various (patho)physiological functions. Here, two crystal structures of the E2 domain of APLP1 are presented in the apo form and in complex with a heparin dodecasaccharide at 2.5 Å resolution. The apo structure of APLP1 E2 revealed an unfolded and hence flexible N-terminal helix αA. The (APLP1 E2){sub 2}–(heparin){sub 2} complex structure revealed two distinct binding modes, with APLP1 E2 explicitly recognizing the heparin terminus but also interacting with a continuous heparin chain. The latter only requires a certain register of the sugar moieties that fits to a positively charged surface patch and contributes to the general heparin-binding capability of APP-family proteins. Terminal binding of APLP1 E2 to heparin specifically involves a structure of the nonreducing end that is very similar to heparanase-processed HS chains. These data reveal a conserved mechanism for the binding of APP-family proteins to HS and imply a specific regulatory role of HS modifications in the biology of APP and APP-like proteins.

  1. Beta-amyloid precursor protein cleavage enzyme-1 expression in adult rat retinal neurons in the early period after lead exposure

    Institute of Scientific and Technical Information of China (English)

    Jufang Huang; Kai Huang; Lei Shang; Hui Wang; Xiaoxin Yan; Kun Xiong

    2011-01-01

    Previous studies have reported that non-human primates and rodents exposed to lead during brain development may become dependent on the deposition of pre-determined β-amyloid protein (Aβ), and exhibit upregulation of β-site amyloid precursor protein expression in old age. However, further evidence is required to elucidate the precise relationship and molecular mechanisms underlying the effects of early lead exposure on excessive Aβ production in adult mammals. The present study investigated the effects of lead exposure on expression of β-amyloid precursor protein cleavage enzyme-1 (BACE-1) in the rat retina and the production of Aβ in early development, using the retina as a window for studying Alzheimer's disease. Adult rats were intraocularly injected with different doses of lead acetate (10 μmol/L, 100 μmol/L, 1 mmol/L, 10 mmol/L and 100 mmol/L). The results revealed that retinal lead concentration, BACE-1 and its cleavage products β-C-terminal fragment and retina Aβ1-40 were all significantly increased in almost all of the lead exposure groups 48 hours later in a dose-dependent manner. The only exception was the 10 μmol/L group. The distribution of BACE-1 in the retina did not exhibit obvious changes, and no distinctive increase in the activation of retinal microglia was apparent. Similarly, retinal synaptophysin expression did not exhibit any clear changes. These data suggest that lead exposure can result in the upregulation of retinal neuron BACE-1 expression in the early period of development and further increase the overproduction of Aβ1-40 in the retina. Our results provided novel insight into the molecular mechanisms underlying environmentally-induced Alzheimer's disease.

  2. Differentiating the Influences of Aging and Adiposity on Brain Weights, Levels of Serum and Brain Cytokines, Gastrointestinal Hormones, and Amyloid Precursor Protein.

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    Banks, William A; Abrass, Christine K; Hansen, Kim M

    2016-01-01

    Aging and obesity exert important effects on disease. Differentiating these effects is difficult, however, because weight gain often accompanies aging. Here, we used a nested design of aged, calorically restricted, and refed rats to measure changes in brain and blood levels of cytokines and gastrointestinal hormones, brain amyloid precursor protein levels, and brain and body weights. By comparing groups and using path analysis, we found divergent influences of chronological aging versus body weight, our main findings being (i) changes in whole brain weight and serum macrophage colony-stimulating factor levels correlated better with body weight than with chronological aging, (ii) a decrease in brain cytokines and brain plasminogen activator inhibitor levels correlated better with chronological aging than with body weight, (iii) serum erythropoietin levels were influenced by both body weight and aging, (iv) serum plasminogen activator inhibitor, serum cytokines, and brain tumor necrosis factor were not influenced by aging or body weight, and (v) brain amyloid precursor protein more closely related to body weight and serum levels of gastrointestinal hormones than to brain weight, chronological aging, or cytokines. These findings show that although aging and body weight interact, their influences are distinct not only among various cytokines and hormones but also between the central nervous system and the peripheral tissue compartments.

  3. Data on amyloid precursor protein accumulation, spontaneous physical activity, and motor learning after traumatic brain injury in the triple-transgenic mouse model of Alzheimer׳s disease.

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    Kishimoto, Yasushi; Shishido, Hajime; Sawanishi, Mayumi; Toyota, Yasunori; Ueno, Masaki; Kubota, Takashi; Kirino, Yutaka; Tamiya, Takashi; Kawai, Nobuyuki

    2016-12-01

    This data article contains supporting information regarding the research article entitled "Traumatic brain injury accelerates amyloid-β deposition and impairs spatial learning in the triple-transgenic mouse model of Alzheimer׳s disease" (H. Shishido, Y. Kishimoto, N. Kawai, Y. Toyota, M. Ueno, T. Kubota, Y. Kirino, T. Tamiya, 2016) [1]. Triple-transgenic (3×Tg)-Alzheimer׳s disease (AD) model mice exhibited significantly poorer spatial learning than sham-treated 3×Tg-AD mice 28 days after traumatic brain injury (TBI). Correspondingly, amyloid-β (Aβ) deposition within the hippocampus was significantly greater in 3×Tg-AD mice 28 days after TBI. However, data regarding the short-term and long-term influences of TBI on amyloid precursor protein (APP) accumulation in AD model mice remain limited. Furthermore, there is little data showing whether physical activity and motor learning are affected by TBI in AD model mice. Here, we provide immunocytochemistry data confirming that TBI induces significant increases in APP accumulation in 3×Tg-AD mice at both 7 days and 28 days after TBI. Furthermore, 3×Tg-AD model mice exhibit a reduced ability to acquire conditioned responses (CRs) during delay eyeblink conditioning compared to sham-treated 3×Tg-AD model mice 28 days after TBI. However, physical activity and motor performance are not significantly changed in TBI-treated 3×Tg-AD model mice.

  4. Transgenic expression of the amyloid-beta precursor protein-intracellular domain does not induce Alzheimer's Disease-like traits in vivo.

    Directory of Open Access Journals (Sweden)

    Luca Giliberto

    Full Text Available BACKGROUND: Regulated intramembranous proteolysis of the amyloid-beta precursor protein by the gamma-secretase yields amyloid-beta, which is the major component of the amyloid plaques found in Alzheimer's disease (AD, and the APP intracellular domain (AID. In vitro studies have involved AID in apoptosis and gene transcription. In vivo studies, which utilize transgenic mice expressing AID in the forebrain, only support a role for AID in apoptosis but not gene transcription. METHODOLOGY/PRINCIPAL FINDINGS: Here, we have further characterized several lines of AID transgenic mice by crossing them with human Tau-bearing mice, to determine whether over-expression of AID in the forebrain provokes AD-like pathologic features in this background. We have found no evidence that AID overexpression induces AD-like characteristics, such as activation of GSK-3beta, hyperphosphorylation of Tau and formation of neurofibrillary pathology. CONCLUSIONS/SIGNIFICANCE: Overall, these data suggest that AID transgenic mice do not represent a model that reproduces the overt biochemical and anatomo-pathologic lesions observed in AD patients. They can still be a valuable tool to understand the role of AID in enhancing the cell sensitivity to apoptotic stimuli, whose pathways still need to be characterized.

  5. An Alzheimer Disease-linked Rare Mutation Potentiates Netrin Receptor Uncoordinated-5C-induced Signaling That Merges with Amyloid β Precursor Protein Signaling.

    Science.gov (United States)

    Hashimoto, Yuichi; Toyama, Yuka; Kusakari, Shinya; Nawa, Mikiro; Matsuoka, Masaaki

    2016-06-03

    A missense mutation (T835M) in the uncoordinated-5C (UNC5C) netrin receptor gene increases the risk of late-onset Alzheimer disease (AD) and also the vulnerability of neurons harboring the mutation to various insults. The molecular mechanisms underlying T835M-UNC5C-induced death remain to be elucidated. In this study, we show that overexpression of wild-type UNC5C causes low-grade death, which is intensified by an AD-linked mutation T835M. An AD-linked survival factor, calmodulin-like skin protein (CLSP), and a natural ligand of UNC5C, netrin1, inhibit this death. T835M-UNC5C-induced neuronal cell death is mediated by an intracellular death-signaling cascade, consisting of death-associated protein kinase 1/protein kinase D/apoptosis signal-regulating kinase 1 (ASK1)/JNK/NADPH oxidase/caspases, which merges at ASK1 with a death-signaling cascade, mediated by amyloid β precursor protein (APP). Notably, netrin1 also binds to APP and partially inhibits the death-signaling cascade, induced by APP. These results may provide new insight into the amyloid β-independent pathomechanism of AD.

  6. Novel 5' untranslated region directed blockers of iron-regulatory protein-1 dependent amyloid precursor protein translation: implications for down syndrome and Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Sanghamitra Bandyopadhyay

    Full Text Available We reported that iron influx drives the translational expression of the neuronal amyloid precursor protein (APP, which has a role in iron efflux. This is via a classic release of repressor interaction of APP mRNA with iron-regulatory protein-1 (IRP1 whereas IRP2 controls the mRNAs encoding the L- and H-subunits of the iron storage protein, ferritin. Here, we identified thirteen potent APP translation blockers that acted selectively towards the uniquely configured iron-responsive element (IRE RNA stem loop in the 5' untranslated region (UTR of APP mRNA. These agents were 10-fold less inhibitory of 5'UTR sequences of the related prion protein (PrP mRNA. Western blotting confirmed that the 'ninth' small molecule in the series selectively reduced neural APP production in SH-SY5Y cells at picomolar concentrations without affecting viability or the expression of α-synuclein and ferritin. APP blocker-9 (JTR-009, a benzimidazole, reduced the production of toxic Aβ in SH-SY5Y neuronal cells to a greater extent than other well tolerated APP 5'UTR-directed translation blockers, including posiphen, that were shown to limit amyloid burden in mouse models of Alzheimer's disease (AD. RNA binding assays demonstrated that JTR-009 operated by preventing IRP1 from binding to the IRE in APP mRNA, while maintaining IRP1 interaction with the H-ferritin IRE RNA stem loop. Thus, JTR-009 constitutively repressed translation driven by APP 5'UTR sequences. Calcein staining showed that JTR-009 did not indirectly change iron uptake in neuronal cells suggesting a direct interaction with the APP 5'UTR. These studies provide key data to develop small molecules that selectively reduce neural APP and Aβ production at 10-fold lower concentrations than related previously characterized translation blockers. Our data evidenced a novel therapeutic strategy of potential impact for people with trisomy of the APP gene on chromosome 21, which is a phenotype long associated with Down

  7. Novel 5' untranslated region directed blockers of iron-regulatory protein-1 dependent amyloid precursor protein translation: implications for down syndrome and Alzheimer's disease.

    Science.gov (United States)

    Bandyopadhyay, Sanghamitra; Cahill, Catherine; Balleidier, Amelie; Huang, Conan; Lahiri, Debomoy K; Huang, Xudong; Rogers, Jack T

    2013-01-01

    We reported that iron influx drives the translational expression of the neuronal amyloid precursor protein (APP), which has a role in iron efflux. This is via a classic release of repressor interaction of APP mRNA with iron-regulatory protein-1 (IRP1) whereas IRP2 controls the mRNAs encoding the L- and H-subunits of the iron storage protein, ferritin. Here, we identified thirteen potent APP translation blockers that acted selectively towards the uniquely configured iron-responsive element (IRE) RNA stem loop in the 5' untranslated region (UTR) of APP mRNA. These agents were 10-fold less inhibitory of 5'UTR sequences of the related prion protein (PrP) mRNA. Western blotting confirmed that the 'ninth' small molecule in the series selectively reduced neural APP production in SH-SY5Y cells at picomolar concentrations without affecting viability or the expression of α-synuclein and ferritin. APP blocker-9 (JTR-009), a benzimidazole, reduced the production of toxic Aβ in SH-SY5Y neuronal cells to a greater extent than other well tolerated APP 5'UTR-directed translation blockers, including posiphen, that were shown to limit amyloid burden in mouse models of Alzheimer's disease (AD). RNA binding assays demonstrated that JTR-009 operated by preventing IRP1 from binding to the IRE in APP mRNA, while maintaining IRP1 interaction with the H-ferritin IRE RNA stem loop. Thus, JTR-009 constitutively repressed translation driven by APP 5'UTR sequences. Calcein staining showed that JTR-009 did not indirectly change iron uptake in neuronal cells suggesting a direct interaction with the APP 5'UTR. These studies provide key data to develop small molecules that selectively reduce neural APP and Aβ production at 10-fold lower concentrations than related previously characterized translation blockers. Our data evidenced a novel therapeutic strategy of potential impact for people with trisomy of the APP gene on chromosome 21, which is a phenotype long associated with Down syndrome (DS

  8. Critical analysis of the use of β-site amyloid precursor protein-cleaving enzyme 1 inhibitors in the treatment of Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Evin G

    2014-01-01

    Full Text Available Genevieve Evin,1,2 Adel Barakat21Oxidation Biology Laboratory, Mental Health Research Institute, Florey Institute of Neuroscience and Mental Health, University of Melbourne, 2Department of Pathology, University of Melbourne, Parkville, VIC, AustraliaAbstract: Alzheimer's disease (AD is the major cause of dementia in the elderly and an unmet clinical challenge. A variety of therapies that are currently under development are directed to the amyloid cascade. Indeed, the accumulation and toxicity of amyloid-β (Aβ is believed to play a central role in the etiology of the disease, and thus rational interventions are aimed at reducing the levels of Aβ in the brain. Targeting β-site amyloid precursor protein-cleaving enzyme (BACE-1 represents an attractive strategy, as this enzyme catalyzes the initial and rate-limiting step in Aβ production. Observation of increased levels of BACE1 and enzymatic activity in the brain, cerebrospinal fluid, and platelets of patients with AD and mild cognitive impairment supports the potential benefits of BACE1 inhibition. Numerous potent inhibitors have been generated, and many of these have been proved to lower Aβ levels in the brain of animal models. Over 10 years of intensive research on BACE1 inhibitors has now culminated in advancing half a dozen of these drugs into human trials, yet translating the in vitro and cellular efficacy of BACE1 inhibitors into preclinical and clinical trials represents a challenge. This review addresses the promises and also the potential problems associated with BACE1 inhibitors for AD therapy, as the complex biological function of BACE1 in the brain is becoming unraveled.Keywords: amyloid, dementia, secretase, aspartyl protease, neuregulin

  9. [Compensatory mechanisms to heal neuroplasticity impairment under Alzheiemer's disease neurodegeneration. I: The role of amyloid beta and its' precursor protein].

    Science.gov (United States)

    Kudinov, A R; Kudinova, N V; Kezlia, E V; Kozyrev, K M; Medvedev, A E; Berezov, T T

    2012-01-01

    In-depth scholar literature analysis of Alzheimer's disease neurodegenerative features of amyloid beta protein neurochemistry modification and excessive phosphorylation of tau protein (and associated neuronal cytoskeleton rearrangements) are secondary phenomena. At early disease stage these neurobiochemical mechanisms are reversible and serve to heal an impairment of biophysical properties of neuronal membranes, neurotransmission, basic neuronal function and neuroplasticity, while preserving anatomical and functional brain fields. Abeta and tau could well serve to biochemically restore physico-chemical properties of neual membranes due to a role these proteins play in lipid metabolism. Under such scenario therapeutic block of aggregation and plaque formation of Abeta and inhibition of tau phosphorylation, as well as pharmaceutical modification of other secondary neurodegenerative features (such as a cascade of oxidative stress reactions) are unable to provide an effective cure of Alzheimer's disease and related pathologies of the Central and peripheral nervous systems, because they are not arraying primary pathagenetic cause. We review the role of Abeta in compensatory mechanisms of neuroplasticity restoration under normal physiological condition and Alzheimer's disease.

  10. Molecular mechanism of the intramembrane cleavage of the β-carboxyl terminal fragment of amyloid precursor protein by γ-secretase

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    Maho eMorishima-Kawashima

    2014-11-01

    Full Text Available Amyloid β-protein (Aβ plays a central role in the pathogenesis of Alzheimer’s disease, the most common age-associated neurodegenerative disorder. Aβ is generated through intramembrane proteolysis of the β-carboxyl terminal fragment (βCTF of β-amyloid precursor protein (APP by γ-secretase. The initial cleavage by γ-secretase occurs in the membrane/cytoplasm boundary of the βCTF, liberating the APP intracellular domain (AICD. The remaining βCTFs, which are truncated at the C-terminus (longer Aβs, are then cropped sequentially in a stepwise manner, predominantly at three residue intervals, to generate Aβ. There are two major Aβ product lines which generate Aβ40 and Aβ42 with concomitant release of three and two tripeptides, respectively. Additionally, many alternative cleavages occur, releasing peptides with three to six residues. These modulate the Aβ product lines and define the species and quantity of Aβ generated. Here, we review our current understanding of the intramembrane cleavage of the βCTF by γ-secretase, which may contribute to the future goal of developing an efficient therapeutic strategy for Alzheimer’s disease.

  11. Structural Studies of the Alzheimer's Amyloid Precursor Protein Copper-Binding Domain Reveal How It Binds Copper Ions

    Energy Technology Data Exchange (ETDEWEB)

    Kong, G.K.-W.; Adams, J.J.; Harris, H.H.; Boas, J.F.; Curtain, C.C.; Galatis, D.; Master, C.L.; Barnham, K.J.; McKinstry, W.J.; Cappai, R.; Parker, M.W.; /Sydney U.

    2007-07-09

    Alzheimer's disease (AD) is the major cause of dementia. Amyloid {beta} peptide (A {beta}), generated by proteolytic cleavage of the amyloid precursor protein (APP), is central to AD pathogenesis. APP can function as a metalloprotein and modulate copper (Cu) transport, presumably via its extracellular Cu-binding domain (CuBD). Cu binding to the CuBD reduces A{beta} levels, suggesting that a Cu mimetic may have therapeutic potential. We describe here the atomic structures of apo CuBD from three crystal forms and found they have identical Cu-binding sites despite the different crystal lattices. The structure of Cu[2+]-bound CuBD reveals that the metal ligands are His147, His151, Tyrl68 and two water molecules, which are arranged in a square pyramidal geometry. The site resembles a Type 2 non-blue Cu center and is supported by electron paramagnetic resonance and extended X-ray absorption fine structure studies. A previous study suggested that Met170 might be a ligand but we suggest that this residue plays a critical role as an electron donor in CuBDs ability to reduce Cu ions. The structure of Cu[+]-bound CuBD is almost identical to the Cu[2+]-bound structure except for the loss of one of the water ligands. The geometry of the site is unfavorable for Cu[+], thus providing a mechanism by which CuBD could readily transfer Cu ions to other proteins.

  12. Sortilin-related receptor 1 interacts with amyloid precursor protein and is activated by 6-shogaol, leading to inhibition of the amyloidogenic pathway.

    Science.gov (United States)

    Na, Ji-Young; Song, Kibbeum; Lee, Ju-Woon; Kim, Sokho; Kwon, Jungkee

    2017-03-18

    Sortilin-related receptor 1 (SORL1) is a neuronal sorting protein that reduces amyloid precursor protein (APP) trafficking to secretases that generate amyloid beta (Aβ). Although 6-shogaol, a constituent of ginger, has been reported to have anti-inflammatory and anti-oxidant effects on neuronal cells, research regarding the activation of SORL1 has not yet been reported. Here, we aimed to investigate whether 6-shogaol contributes to the increases in SORL1 that are related to Alzheimer's disease (AD). To clarify the effect of 6-shogaol as a possible activator of SORL1, we used SORL1 siRNA as a blockade of SORL1 in hippocampal neuronal cells (HT22). We found that SORL1 siRNA treatment naturally inhibited SORL1 and led to increases in β-secretase APP cleaving enzyme (BACE), secreted APP-β (sAPPβ) and Aβ. In contrast, 6-shogaol-mediated activation of SORL1 significantly downregulated BACE, sAPPβ, and Aβ in both in vitro HT22 cells and in vivo APPSw/PS1-dE9 Tg mice. Therefore, SORL1 activation by 6-shogaol provides neuronal cell survival through the inhibition of Aβ production. These results indicate that 6-shogaol should be regarded as an SORL1 activator and a potential preventive agent for the treatment of AD.

  13. Evidence that the amyloidprotein precursor intracellular domain, AICD, derives from β-secretase-generated C-terminal fragment.

    Science.gov (United States)

    Flammang, Brice; Pardossi-Piquard, Raphaëlle; Sevalle, Jean; Debayle, Delphine; Dabert-Gay, Anne-Sophie; Thévenet, Aurélie; Lauritzen, Inger; Checler, Frédéric

    2012-01-01

    One of the major pathological hallmarks of brains affected with Alzheimer's disease (AD) is the senile plaque, an extracellular deposit mainly composed of a set of highly insoluble peptides of various lengths (39-43 amino acids) referred to as amyloid-β (Aβ) peptides. Aβ peptides are derived from combined proteolytic cleavages undergone on the amyloidprotein precursor (AβPP) by a set of enzymes called secretases. Several lines of anatomical and biological evidence suggest that Aβ peptides would not account for all pathological stigmata and molecular dysfunctions taking place in AD. In amyloidogenic and non-amyloidogenic pathways, AβPP first undergoes β- or α-secretases-mediated cleavages yielding C99 and C83, respectively. These two membrane-embedded C-terminal fragments are both potential targets of subsequent γ-secretase-mediated proteolysis. The latter cleavage not only generates either p3 or Aβ peptides but similarly gives rise to an AβPP IntraCellular Domain (AICD fragment) that could modulate the transcription of several genes linked to AD pathology. It is therefore striking that AICD theoretically derives from both amyloidogenic and non-amyloidogenic AβPP processing pathways. Here we show that AICD predominantly derives from C99 by means of recombinant substrates and transiently transfected cells expressing C99. Our data suggest a preferred pathogenic pathway for AICD production and suggests that this fragment, in addition to C99 and Aβ peptides, could contribute to AD pathology.

  14. β-Secretase inhibitor increases amyloidprecursor protein level in rat brain cortical primary neurons induced by okadaic acid

    Institute of Scientific and Technical Information of China (English)

    YU Chun-Jiang; WANG Wei-zhi; LIU Wei

    2008-01-01

    Background Senile plaques and neurofibrillary tangles (NFTs) represent two of the major histopathological hallmarks of Alzheimer's disease (AD). The plaques are primarily composed of aggregated amyloid β (Aβ) peptides. The processing of amyloidprecursor protein (AβPP) in okadaic acid (OA)-induced tau phosphorylation primary neurons was studied.Methods Primary cultures of rat brain cortical neurons were treated with OA and β-secretase inhibitor. Neurons' viability was measured. AβPP processing was examined by immunocytochemistry and Western blotting with specific antibodies against the AβPP-N-terminus (NT) and AβPP-C-terminus (CT).Results Ten nrnol/L OA had a time-dependent suppression effect on primary neurons' viability. The suppression effect was alleviated markedly by pretreatment with β-secretase inhibitor. After OA treatment, both AβPP and β-C-terminal fragment (βCTF) were significantly increased in neurons. AβPP level was increased further in neurons pretreated with β-secretase inhibitor.Conclusions In OA-induced tau phosphorylation cell model, inhibition of β-secretase may protect neurons from death induced by OA. Because of increased accumulation of AβPP in neurons after OA treatment, more AβPP turns to be cleaved by β-secretase, producing neurotoxic βCTF. As a potential effective therapeutic target, β-secretase is worth investigating further.

  15. Iron and the translation of the amyloid precursor protein (APP) and ferritin mRNAs: riboregulation against neural oxidative damage in Alzheimer's disease.

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    Rogers, Jack T; Bush, Ashley I; Cho, Hyan-Hee; Smith, Deborah H; Thomson, Andrew M; Friedlich, Avi L; Lahiri, Debomoy K; Leedman, Peter J; Huang, Xudong; Cahill, Catherine M

    2008-12-01

    The essential metals iron, zinc and copper deposit near the Abeta (amyloid beta-peptide) plaques in the brain cortex of AD (Alzheimer's disease) patients. Plaque-associated iron and zinc are in neurotoxic excess at 1 mM concentrations. APP (amyloid precursor protein) is a single transmembrane metalloprotein cleaved to generate the 40-42-amino-acid Abetas, which exhibit metal-catalysed neurotoxicity. In health, ubiquitous APP is cleaved in a non-amyloidogenic pathway within its Abeta domain to release the neuroprotective APP ectodomain, APP(s). To adapt and counteract metal-catalysed oxidative stress, as during reperfusion from stroke, iron and cytokines induce the translation of both APP and ferritin (an iron storage protein) by similar mechanisms. We reported that APP was regulated at the translational level by active IL (interleukin)-1 (IL-1-responsive acute box) and IRE (iron-responsive element) RNA stem-loops in the 5' untranslated region of APP mRNA. The APP IRE is homologous with the canonical IRE RNA stem-loop that binds the iron regulatory proteins (IRP1 and IRP2) to control intracellular iron homoeostasis by modulating ferritin mRNA translation and transferrin receptor mRNA stability. The APP IRE interacts with IRP1 (cytoplasmic cis-aconitase), whereas the canonical H-ferritin IRE RNA stem-loop binds to IRP2 in neural cell lines, and in human brain cortex tissue and in human blood lysates. The same constellation of RNA-binding proteins [IRP1/IRP2/poly(C) binding protein] control ferritin and APP translation with implications for the biology of metals in AD.

  16. Mild oxidative stress induces redistribution of BACE1 in non-apoptotic conditions and promotes the amyloidogenic processing of Alzheimer's disease amyloid precursor protein.

    Directory of Open Access Journals (Sweden)

    Jiang-Li Tan

    Full Text Available BACE1 is responsible for β-secretase cleavage of the amyloid precursor protein (APP, which represents the first step in the production of amyloid β (Aβ peptides. Previous reports, by us and others, have indicated that the levels of BACE1 protein and activity are increased in the brain cortex of patients with Alzheimer's disease (AD. The association between oxidative stress (OS and AD has prompted investigations that support the potentiation of BACE1 expression and enzymatic activity by OS. Here, we have established conditions to analyse the effects of mild, non-lethal OS on BACE1 in primary neuronal cultures, independently from apoptotic mechanisms that were shown to impair BACE1 turnover. Six-hour treatment of mouse primary cortical cells with 10-40 µM hydrogen peroxide did not significantly compromise cell viability but it did produce mild oxidative stress (mOS, as shown by the increased levels of reactive radical species and activation of p38 stress kinase. The endogenous levels of BACE1 mRNA and protein were not significantly altered in these conditions, whereas a toxic H2O2 concentration (100 µM caused an increase in BACE1 protein levels. Notably, mOS conditions resulted in increased levels of the BACE1 C-terminal cleavage product of APP, β-CTF. Subcellular fractionation techniques showed that mOS caused a major rearrangement of BACE1 localization from light to denser fractions, resulting in an increased distribution of BACE1 in fractions containing APP and markers for trans-Golgi network and early endosomes. Collectively, these data demonstrate that mOS does not modify BACE1 expression but alters BACE1 subcellular compartmentalization to favour the amyloidogenic processing of APP, and thus offer new insight in the early molecular events of AD pathogenesis.

  17. The E1 copper binding domain of full-length amyloid precursor protein mitigates copper-induced growth inhibition in brain metastatic prostate cancer DU145 cells.

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    Gough, Mallory; Blanthorn-Hazell, Sophee; Delury, Craig; Parkin, Edward

    2014-10-31

    Copper plays an important role in the aetiology and growth of tumours and levels of the metal are increased in the serum and tumour tissue of patients affected by a range of cancers including prostate cancer (PCa). The molecular mechanisms that enable cancer cells to proliferate in the presence of elevated copper levels are, therefore, of key importance in our understanding of tumour growth progression. In the current study, we have examined the role played by the amyloid precursor protein (APP) in mitigating copper-induced growth inhibition of the PCa cell line, DU145. A range of APP molecular constructs were stably over-expressed in DU145 cells and their effects on cell proliferation in the presence of copper were monitored. Our results show that endogenous APP expression was induced by sub-toxic copper concentrations in DU145 cells and over-expression of the wild-type protein was able to mitigate copper-induced growth inhibition via a mechanism involving the cytosolic and E1 copper binding domains of the full-length protein. APP likely represents one of a range of copper binding proteins that PCa cells employ in order to ensure efficient proliferation despite elevated concentrations of the metal within the tumour microenvironment. Targeting the expression of such proteins may contribute to therapeutic strategies for the treatment of cancers.

  18. A lentiviral sponge for miR-101 regulates RanBP9 expression and amyloid precursor protein metabolism in hippocampal neurons

    Directory of Open Access Journals (Sweden)

    Christian eBarbato

    2014-02-01

    Full Text Available Neurodegeneration associated with amyloid β (Aβ peptide accumulation, synaptic loss, and memory impairment are pathophysiological features of Alzheimer's disease (AD. Numerous microRNAs regulate amyloid precursor protein (APP expression and metabolism. We previously reported that miR-101 is a negative regulator of APP expression in cultured hippocampal neurons. In this study, a search for predicted APP metabolism-associated miR-101 targets led to the identification of a conserved miR-101 binding site within the 3’ untranslated region (UTR of the mRNA encoding Ran-binding protein 9 (RanBP9. RanBP9 increases APP processing by β-amyloid converting enzyme 1 (BACE1, secretion of soluble APPβ (sAPPβ, and generation of Aβ. MiR-101 significantly reduced reporter gene expression when co-transfected with a RanBP9 3'-UTR reporter construct, while site-directed mutagenesis of the predicted miR-101 target site eliminated the reporter response. To investigate the effect of stable inhibition of miR-101 both in vitro and in vivo, a microRNA sponge was developed to bind miR-101 and derepress its targets. Four tandem bulged miR-101 responsive elements (REs, located downstream of the enhanced green fluorescence protein (EGFP open reading frame and driven by the synapsin promoter, were placed in a lentiviral vector to create the pLSyn-miR-101 sponge. Delivery of the sponge to primary hippocampal neurons significantly increased both APP and RanBP9 expression, as well as sAPPβ levels in the conditioned medium. Importantly, silencing of endogenous RanBP9 reduced sAPPβ levels in miR-101 sponge-containing hippocampal cultures, indicating that miR-101 inhibition may increase amyloidogenic processing of APP by RanBP9. Lastly, the impact of miR-101 on its targets was demonstrated in vivo by intrahippocampal injection of the pLSyn-miR-101 sponge into C57BL6 mice. This study thus provides the basis for studying the consequences of long-term miR-101 inhibition on

  19. The leucine-rich repeats of LINGO-1 are not required for self-interaction or interaction with the amyloid precursor protein.

    Science.gov (United States)

    Stein, Thomas; Walmsley, Adrian Robert

    2012-02-10

    LINGO-1 (leucine rich repeat and Ig domain containing Nogo receptor interacting protein-1) is a central nervous system transmembrane protein which simultaneously interacts with the Nogo-66 receptor and p75(NTR) or TROY on neurons to form a receptor complex responsible for myelin-mediated neurite outgrowth inhibition. On oligodendroglial cells, LINGO-1 interacts with p75(NTR) to constitutively inhibit multiple aspects of oligodendrocyte differentiation. Recently, LINGO-1 was identified as an in vivo interacting partner of the amyloid precursor protein (APP) and, correspondingly, cellular LINGO-1 expression was found to augment the release of the Abeta peptide, the potential causative agent of Alzheimer's disease. In addition, the recombinant LINGO-1 ectodomain has been shown to self-interact in solution and after crystallisation. Here, we have used deletional mutagenesis to identify the regions on LINGO-1 that are involved in homo- and heterotypic interactions. We have found that the N-terminal region containing the leucine-rich repeats along with the transmembrane and cytoplasmic domains of LINGO-1 are not required for self-interaction or interaction with APP.

  20. Differential interaction of Apolipoprotein-E isoforms with insulin receptors modulates brain insulin signaling in mutant human amyloid precursor protein transgenic mice.

    Science.gov (United States)

    Chan, Elizabeth S; Chen, Christopher; Cole, Gregory M; Wong, Boon-Seng

    2015-09-08

    It is unclear how human apolipoprotein E4 (ApoE4) increases the risk for Alzheimer's disease (AD). Although Aβ levels can lead to insulin signaling impairment, these experiments were done in the absence of human ApoE. To examine ApoE role, we crossed the human ApoE-targeted replacement mice with mutant human amyloid precursor protein (APP) mice. In 26 week old mice with lower Aβ levels, the expression and phosphorylation of insulin signaling proteins remained comparable among APP, ApoE3xAPP and ApoE4xAPP mouse brains. When the mice aged to 78 weeks, these proteins were markedly reduced in APP and ApoE4xAPP mouse brains. While Aβ can bind to insulin receptor, how ApoE isoforms modulate this interaction remains unknown. Here, we showed that ApoE3 had greater association with insulin receptor as compared to ApoE4, regardless of Aβ42 concentration. In contrast, ApoE4 bound more Aβ42 with increasing peptide levels. Using primary hippocampal neurons, we showed that ApoE3 and ApoE4 neurons are equally sensitive to physiological levels of insulin. However, in the presence of Aβ42, insulin failed to elicit a downstream response only in ApoE4 hippocampal neurons. Taken together, our data show that ApoE genotypes can modulate this Aβ-mediated insulin signaling impairment.

  1. Potential Natural Products for Alzheimer’s Disease: Targeted Search Using the Internal Ribosome Entry Site of Tau and AmyloidPrecursor Protein

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    Yun-Chieh Tasi

    2015-04-01

    Full Text Available Overexpression of the amyloid precursor protein (APP and the hyperphosphorylation of the tau protein are vital in the understanding of the cause of Alzheimer’s disease (AD. As a consequence, regulation of the expression of both APP and tau proteins is one important approach in combating AD. The APP and tau proteins can be targeted at the levels of transcription, translation and protein structural integrity. This paper reports the utilization of a bi-cistronic vector containing either APP or tau internal ribosome entry site (IRES elements flanked by β-galactosidase gene (cap-dependent and secreted alkaline phosphatase (SEAP (cap-independent to discern the mechanism of action of memantine, an N-methyl-d-aspartate (NMDA receptor antagonist. Results indicate that memantine could reduce the activity of both the APP and tau IRES at a concentration of ~10 μM (monitored by SEAP activity without interfering with the cap-dependent translation as monitored by the β-galactosidase assay. Western blot analysis of the tau protein in neuroblastoma (N2A and rat hippocampal cells confirmed the halting of the expression of the tau proteins. We also employed this approach to identify a preparation named NB34, extracts of Boussingaultia baselloides (madeira-vine fermented with Lactobacillus spp., which can function similarly to memantine in both IRES of APP and Tau. The water maze test demonstrated that NB34 could improve the spatial memory of a high fat diet induced neurodegeneration in apolipoprotein E-knockout (ApoE−/− mice. These results revealed that the bi-cistronic vector provided a simple, and effective platform in screening and establishing the mechanistic action of potential compounds for the treatment and management of AD.

  2. Early in vivo Effects of the Human Mutant AmyloidProtein Precursor (hAβPPSwInd) on the Mouse Olfactory Bulb.

    Science.gov (United States)

    Rusznák, Zoltán; Kim, Woojin Scott; Hsiao, Jen-Hsiang T; Halliday, Glenda M; Paxinos, George; Fu, YuHong

    2016-01-01

    The amyloidprotein precursor (AβPP) has long been linked to Alzheimer's disease (AD). Using J20 mice, which express human AβPP with Swedish and Indiana mutations, we studied early pathological changes in the olfactory bulb. The presence of AβPP/amyloid-β (Aβ) was examined in mice aged 3 months (before the onset of hippocampal Aβ deposition) and over 5 months (when hippocampal Aβ deposits are present). The number of neurons, non-neurons, and proliferating cells was assessed using the isotropic fractionator method. Our results demonstrate that although AβPP is overexpressed in some of the mitral cells, widespread Aβ deposition and microglia aggregates are not prevalent in the olfactory bulb. The olfactory bulbs of the younger J20 group harbored significantly fewer neurons than those of the age-matched wild-type mice (5.57±0.13 million versus 6.59±0.36 million neurons; p = 0.011). In contrast, the number of proliferating cells was higher in the young J20 than in the wild-type group (i.e., 6617±425 versus 4455±623 cells; p = 0.011). A significant increase in neurogenic activity was also observed in the younger J20 olfactory bulb. In conclusion, our results indicate that (1) neurons participating in the mouse olfactory function overexpress AβPP; (2) the cellular composition of the young J20 olfactory bulb is different from that of wild-type littermates; (3) these differences may reflect altered neurogenic activity and/or delayed development of the J20 olfactory system; and (4) AβPP/Aβ-associated pathological changes that take place in the J20 hippocampus and olfactory bulb are not identical.

  3. Differential effects of 24-hydroxycholesterol and 27-hydroxycholesterol on β-amyloid precursor protein levels and processing in human neuroblastoma SH-SY5Y cells

    Directory of Open Access Journals (Sweden)

    Schommer Eric

    2009-01-01

    Full Text Available Abstract Background Activation of the liver × receptors (LXRs by exogenous ligands stimulates the degradation of β-amyloid 1–42 (Aβ42, a peptide that plays a central role in the pathogenesis of Alzheimer's disease (AD. The oxidized cholesterol products (oxysterols, 24-hydroxycholesterol (24-OHC and 27-hydroxycholesterol (27-OHC, are endogenous activators of LXRs. However, the mechanisms by which these oxysterols may modulate Aβ42 levels are not well known. Results We determined the effect of 24-OHC and/or 27-OHC on Aβ generation in SH-SY5Y cells. We found that while 27-OHC increases levels of Aβ42, 24-OHC did not affect levels of this peptide. Increased Aβ42 levels with 27-OHC are associated with increased levels of β-amyloid precursor protein (APP as well as β-secretase (BACE1, the enzyme that cleaves APP to yield Aβ. Unchanged Aβ42 levels with 24-OHC are associated with increased levels of sAPPα, suggesting that 24-OHC favors the processing of APP to the non-amyloidogenic pathway. Interestingly, 24-OHC, but not 27-OHC, increases levels of the ATP-binding cassette transporters, ABCA1 and ABCG1, which regulate cholesterol transport within and between cells. Conclusion These results suggest that cholesterol metabolites are linked to Aβ42 production. 24-OHC may favor the non-amyloidogenic pathway and 27-OHC may enhance production of Aβ42 by upregulating APP and BACE1. Regulation of 24-OHC: 27-OHC ratio could be an important strategy in controlling Aβ42 levels in AD.

  4. The amyloid precursor protein (APP) intracellular domain regulates translation of p44, a short isoform of p53, through an IRES-dependent mechanism.

    Science.gov (United States)

    Li, Mi; Pehar, Mariana; Liu, Yan; Bhattacharyya, Anita; Zhang, Su-Chun; O'Riordan, Kenneth J; Burger, Corinna; D'Adamio, Luciano; Puglielli, Luigi

    2015-10-01

    p44 is a short isoform of the tumor suppressor protein p53 that is regulated in an age-dependent manner. When overexpressed in the mouse, it causes a progeroid phenotype that includes premature cognitive decline, synaptic defects, and hyperphosphorylation of tau. The hyperphosphorylation of tau has recently been linked to the ability of p44 to regulate transcription of relevant tau kinases. Here, we report that the amyloid precursor protein (APP) intracellular domain (AICD), which results from the processing of the APP, regulates translation of p44 through a cap-independent mechanism that requires direct binding to the second internal ribosome entry site (IRES) of the p53 mRNA. We also report that AICD associates with nucleolin, an already known IRES-specific trans-acting factor that binds with p53 IRES elements and regulates translation of p53 isoforms. The potential biological impact of our findings was assessed in a mouse model of Alzheimer's disease. In conclusion, our study reveals a novel aspect of AICD and p53/p44 biology and provides a possible molecular link between APP, p44, and tau.

  5. Intracellular domains of amyloid precursor-like protein 2 interact with CP2 transcription factor in the nucleus and induce glycogen synthase kinase-3beta expression.

    Science.gov (United States)

    Xu, Y; Kim, H-S; Joo, Y; Choi, Y; Chang, K-A; Park, C H; Shin, K-Y; Kim, S; Cheon, Y-H; Baik, T-K; Kim, J-H; Suh, Y-H

    2007-01-01

    Amyloid precursor protein (APP) is a member of a gene family that includes two APP-like proteins, APLP1 and 2. Recently, it has been reported that APLP1 and 2 undergo presenilin-dependent gamma-secretase cleavage, as does APP, resulting in the release of an approximately 6 kDa intracellular C-terminal domain (ICD), which can translocate into the nucleus. In this study, we demonstrate that the APLP2-ICDs interact with CP2/LSF/LBP1 (CP2) transcription factor in the nucleus and induce the expression of glycogen synthase kinase 3beta (GSK-3beta), which has broad-ranged substrates such as tau- and beta-catenin. The significance of this finding is substantiated by the in vivo evidence of the increase in the immunoreactivities for the nuclear C-terminal fragments of APLP2, and for GSK-3beta in the AD patients' brain. Taken together, these results suggest that APLP2-ICDs contribute to the AD pathogenesis, by inducing GSK-3beta expression through the interaction with CP2 transcription factor in the nucleus.

  6. The Na+/H+ exchanger NHE6 modulates endosomal pH to control processing of amyloid precursor protein in a cell culture model of Alzheimer disease.

    Science.gov (United States)

    Prasad, Hari; Rao, Rajini

    2015-02-27

    Early intervention may be key to safe and effective therapies in patients with Alzheimer disease. Endosomal dysfunction is an early step in neurodegeneration. Endosomes are a major site of production of Aβ peptide from the processing of amyloid precursor protein (APP) by clipping enzymes (β- and γ-secretases). The β-secretase enzyme BACE1 requires acidic lumen pH for optimum function, and acid pH promotes Aβ aggregation. The Na(+)/H(+) exchanger NHE6 provides a leak pathway for protons, limiting luminal acidification by proton pumps. Like APP, NHE6 expression was induced upon differentiation of SH-SY5Y neuroblastoma cells and localized to an endosomal compartment. Therefore, we investigated whether NHE6 expression altered APP localization and processing in a stably transfected cell culture model of human APP expression. We show that co-expression with NHE6 or treatment with the Na(+)/H(+) ionophore monensin shifted APP away from the trans-Golgi network into early and recycling endosomes in HEK293 cells. NHE6 alkalinized the endosomal lumen, similar to monensin, and significantly attenuated APP processing and Aβ secretion. In contrast, Aβ production was elevated upon NHE6 knockdown. We show that NHE6 transcript and protein levels are lowered in Alzheimer brains relative to control. These findings, taken together with emerging genetic evidence linking endosomal Na(+)/H(+) exchangers with Alzheimer disease, suggest that proton leak pathways may regulate Aβ generation and contribute to disease etiology.

  7. β-site amyloid precursor protein cleaving enzyme 1(BACE1) regulates Notch signaling by controlling the cleavage of Jagged 1 (Jag1) and Jagged 2 (Jag2) proteins.

    Science.gov (United States)

    He, Wanxia; Hu, Jinxuan; Xia, Yuxing; Yan, Riqiang

    2014-07-25

    BACE1 is a type I transmembrane aspartyl protease that cleaves amyloid precursor protein at the β-secretase site to initiate the release of β-amyloid peptide. As a secretase, BACE1 also cleaves additional membrane-bound molecules by exerting various cellular functions. In this study, we showed that BACE1 can effectively shed the membrane-anchored signaling molecule Jagged 1 (Jag1).Wealso mapped the cleavage sites of Jag1 by ADAM10 and ADAM17. Although Jag1 shares a high degree of homology with Jag2 in the ectodomain region, BACE1 fails to cleave Jag2 effectively, indicating a selective cleavage of Jag1. Abolished cleavage of Jag1 in BACE1-null mice leads to enhanced astrogenesis and, concomitantly, reduced neurogenesis. This characterization provides biochemical evidence that the Jag1-Notch pathway is under the control of BACE1 activity

  8. The E1 copper binding domain of full-length amyloid precursor protein mitigates copper-induced growth inhibition in brain metastatic prostate cancer DU145 cells

    Energy Technology Data Exchange (ETDEWEB)

    Gough, Mallory, E-mail: m.gough1@lancaster.ac.uk; Blanthorn-Hazell, Sophee, E-mail: s.blanthorn-hazell@lancaster.ac.uk; Delury, Craig, E-mail: c.delury@lancaster.ac.uk; Parkin, Edward, E-mail: e.parkin@lancaster.ac.uk

    2014-10-31

    Highlights: • Copper levels are elevated in the tumour microenvironment. • APP mitigates copper-induced growth inhibition of DU145 prostate cancer (PCa) cells. • The APP intracellular domain is a prerequisite; soluble forms have no effect. • The E1 CuBD of APP is also a prerequisite. • APP copper binding potentially mitigates copper-induced PCa cell growth inhibition. - Abstract: Copper plays an important role in the aetiology and growth of tumours and levels of the metal are increased in the serum and tumour tissue of patients affected by a range of cancers including prostate cancer (PCa). The molecular mechanisms that enable cancer cells to proliferate in the presence of elevated copper levels are, therefore, of key importance in our understanding of tumour growth progression. In the current study, we have examined the role played by the amyloid precursor protein (APP) in mitigating copper-induced growth inhibition of the PCa cell line, DU145. A range of APP molecular constructs were stably over-expressed in DU145 cells and their effects on cell proliferation in the presence of copper were monitored. Our results show that endogenous APP expression was induced by sub-toxic copper concentrations in DU145 cells and over-expression of the wild-type protein was able to mitigate copper-induced growth inhibition via a mechanism involving the cytosolic and E1 copper binding domains of the full-length protein. APP likely represents one of a range of copper binding proteins that PCa cells employ in order to ensure efficient proliferation despite elevated concentrations of the metal within the tumour microenvironment. Targeting the expression of such proteins may contribute to therapeutic strategies for the treatment of cancers.

  9. Presenilin 2 deficiency causes a mild pulmonary phenotype and no changes in amyloid precursor protein processing but enhances the embryonic lethal phenotype of presenilin 1 deficiency.

    Science.gov (United States)

    Herreman, A; Hartmann, D; Annaert, W; Saftig, P; Craessaerts, K; Serneels, L; Umans, L; Schrijvers, V; Checler, F; Vanderstichele, H; Baekelandt, V; Dressel, R; Cupers, P; Huylebroeck, D; Zwijsen, A; Van Leuven, F; De Strooper, B

    1999-10-12

    Mutations in the homologous presenilin 1 (PS1) and presenilin 2 (PS2) genes cause the most common and aggressive form of familial Alzheimer's disease. Although PS1 function and dysfunction have been extensively studied, little is known about the function of PS2 in vivo. To delineate the relationships of PS2 and PS1 activities and whether PS2 mutations involve gain or loss of function, we generated PS2 homozygous deficient (-/-) and PS1/PS2 double homozygous deficient mice. In contrast to PS1(-/-) mice, PS2(-/-) mice are viable and fertile and develop only mild pulmonary fibrosis and hemorrhage with age. Absence of PS2 does not detectably alter processing of amyloid precursor protein and has little or no effect on physiologically important apoptotic processes, indicating that Alzheimer's disease-causing mutations in PS2, as in PS1, result in gain of function. Although PS1(+/-) PS2( -/-) mice survive in relatively good health, complete deletion of both PS2 and PS1 genes causes a phenotype closely resembling full Notch-1 deficiency. These results demonstrate in vivo that PS1 and PS2 have partially overlapping functions and that PS1 is essential and PS2 is redundant for normal Notch signaling during mammalian embryological development.

  10. Structural Characterization of the E2 Domain of APL-1, a C. Elegans Homolog of Human Amyloid Precursor Protein, and its Heparin Binding Site

    Energy Technology Data Exchange (ETDEWEB)

    Hoopes, J.; Liu, X; Xu, X; Demeler, B; Folta-Stogniew, E; Li, C; Ha, Y

    2010-01-01

    The amyloid {beta}-peptide deposit found in the brain tissue of patients with Alzheimer disease is derived from a large heparin-binding protein precursor APP. The biological function of APP and its homologs is not precisely known. Here we report the x-ray structure of the E2 domain of APL-1, an APP homolog in Caenorhabditis elegans, and compare it to the human APP structure. We also describe the structure of APL-1 E2 in complex with sucrose octasulfate, a highly negatively charged disaccharide, which reveals an unexpected binding pocket between the two halves of E2. Based on the crystal structure, we are able to map, using site-directed mutagenesis, a surface groove on E2 to which heparin may bind. Our biochemical data also indicate that the affinity of E2 for heparin is influenced by pH: at pH 5, the binding appears to be much stronger than that at neutral pH. This property is likely caused by histidine residues in the vicinity of the mapped heparin binding site and could be important for the proposed adhesive function of APL-1.

  11. β-Amyloid precursor protein-b is essential for Mauthner cell development in the zebrafish in a Notch-dependent manner.

    Science.gov (United States)

    Banote, Rakesh Kumar; Edling, Malin; Eliassen, Fredrik; Kettunen, Petronella; Zetterberg, Henrik; Abramsson, Alexandra

    2016-05-01

    Amyloid precursor protein (APP) is a transmembrane glycoprotein that has been the subject of intense research because of its implication in Alzheimer's disease. However, the physiological function of APP in the development and maintenance of the central nervous system remains largely unknown. We have previously shown that the APP homologue in zebrafish (Danio rerio), Appb, is required for motor neuron patterning and formation. Here we study the function of Appb during neurogenesis in the zebrafish hindbrain. Partial knockdown of Appb using antisense morpholino oligonucleotides blocked the formation of the Mauthner neurons, uni- or bilaterally, with an aberrant behavior as a consequence of this cellular change. The Appb morphants had decreased neurogenesis, increased notch signaling and notch1a expression at the expense of deltaA/D expression. The Mauthner cell development could be restored either by a general decrease in Notch signaling through γ-secretase inhibition or by a partial knock down of Notch1a. Together, this demonstrates the importance of Appb in neurogenesis and for the first time shows the essential requirement of Appb in the formation of a specific cell type, the Mauthner cell, in the hindbrain during development. Our results suggest that Appb-regulated neurogenesis is mediated through balancing the Notch1a signaling pathway and provide new insights into the development of the Mauthner cell.

  12. The spinal muscular atrophy with pontocerebellar hypoplasia gene VRK1 regulates neuronal migration through an amyloidprecursor protein-dependent mechanism.

    Science.gov (United States)

    Vinograd-Byk, Hadar; Sapir, Tamar; Cantarero, Lara; Lazo, Pedro A; Zeligson, Sharon; Lev, Dorit; Lerman-Sagie, Tally; Renbaum, Paul; Reiner, Orly; Levy-Lahad, Ephrat

    2015-01-21

    Spinal muscular atrophy with pontocerebellar hypoplasia (SMA-PCH) is an infantile SMA variant with additional manifestations, particularly severe microcephaly. We previously identified a nonsense mutation in Vaccinia-related kinase 1 (VRK1), R358X, as a cause of SMA-PCH. VRK1-R358X is a rare founder mutation in Ashkenazi Jews, and additional mutations in patients of different origins have recently been identified. VRK1 is a nuclear serine/threonine protein kinase known to play multiple roles in cellular proliferation, cell cycle regulation, and carcinogenesis. However, VRK1 was not known to have neuronal functions before its identification as a gene mutated in SMA-PCH. Here we show that VRK1-R358X homozygosity results in lack of VRK1 protein, and demonstrate a role for VRK1 in neuronal migration and neuronal stem cell proliferation. Using shRNA in utero electroporation in mice, we show that Vrk1 knockdown significantly impairs cortical neuronal migration, and affects the cell cycle of neuronal progenitors. Expression of wild-type human VRK1 rescues both proliferation and migration phenotypes. However, kinase-dead human VRK1 rescues only the migration impairment, suggesting the role of VRK1 in neuronal migration is partly noncatalytic. Furthermore, we found that VRK1 deficiency in human and mouse leads to downregulation of amyloidprecursor protein (APP), a known neuronal migration gene. APP overexpression rescues the phenotype caused by Vrk1 knockdown, suggesting that VRK1 affects neuronal migration through an APP-dependent mechanism.

  13. O-GlcNAcylation promotes non-amyloidogenic processing of amyloidprotein precursor via inhibition of endocytosis from the plasma membrane.

    Science.gov (United States)

    Chun, Yoon Sun; Park, Yurim; Oh, Hyun Geun; Kim, Tae-Wan; Yang, Hyun Ok; Park, Myoung Kyu; Chung, Sungkwon

    2015-01-01

    Amyloidprotein precursor (AβPP) is transported to the plasma membrane, where it is sequentially cleaved by α-secretase and γ-secretase. This is called non-amyloidogenic pathway since it precludes the production of amyloid-β (Aβ), the main culprit of Alzheimer's disease (AD). Alternatively, once AβPP undergoes clathrin-dependent endocytosis, it can be sequentially cleaved by β-secretase and γ-secretase at endosomes, producing Aβ (amyloidogenic pathway). β-N-acetylglucosamine (GlcNAc) can be attached to serine/threonine residues of the target proteins. This novel type of O-linked glycosylation is called O-GlcNAcylation mediated by O-GlcNAc transferase (OGT). The removal of GlcNAc is mediated by O-GlcNAcase (OGN). Recently, it is shown that O-GlcNAcylation of AβPP increases the non-amyloidogenic pathway. To investigate the regulatory role for O-GlcNAcylation in AβPP processing, we first tested the effects of inhibitor for OGN, PUGNAc, on AβPP metabolism in HeLa cells stably transfected with Swedish mutant form of AβPP. Increasing O-GlcNAcylated AβPP level increased α-secretase product while decreased β-secretase products. We found that PUGNAc increased the trafficking rate of AβPP from the trans-Golgi network to the plasma membrane, and selectively decreased the endocytosis rate of AβPP. These events may contribute to the increased AβPP level in the plasma membrane by PUGNAc. Inhibiting clathrin-dependent endocytosis prevented the effect of PUGNAc on Aβ, suggesting that the effect of PUGNAc was mainly mediated by decreasing AβPP endocytosis. These results strongly indicate that O-GlcNAcylation promotes the plasma membrane localization of AβPP, which enhances the non-amyloidogenic processing of AβPP. Thus, O-GlcNAcylation of AβPP can be a potential therapeutic strategy for AD.

  14. Development of transgenic rats producing human β-amyloid precursor protein as a model for Alzheimer's disease: Transgene and endogenous APP genes are regulated tissue-specifically

    Directory of Open Access Journals (Sweden)

    Chan Anthony WS

    2008-02-01

    Full Text Available Abstract Background Alzheimer's disease (AD is a devastating neurodegenerative disorder that affects a large and growing number of elderly individuals. In addition to idiopathic disease, AD is also associated with autosomal dominant inheritance, which causes a familial form of AD (FAD. Some instances of FAD have been linked to mutations in the β-amyloid protein precursor (APP. Although there are numerous mouse AD models available, few rat AD models, which have several advantages over mice, have been generated. Results Fischer 344 rats expressing human APP driven by the ubiquitin-C promoter were generated via lentiviral vector infection of Fischer 344 zygotes. We generated two separate APP-transgenic rat lines, APP21 and APP31. Serum levels of human amyloid-beta (Aβ40 were 298 pg/ml for hemizygous and 486 pg/ml for homozygous APP21 animals. Serum Aβ42 levels in APP21 homozygous rats were 135 pg/ml. Immunohistochemistry in brain showed that the human APP transgene was expressed in neurons, but not in glial cells. These findings were consistent with independent examination of enhanced green fluorescent protein (eGFP in the brains of eGFP-transgenic rats. APP21 and APP31 rats expressed 7.5- and 3-times more APP mRNA, respectively, than did wild-type rats. Northern blots showed that the human APP transgene, driven by the ubiquitin-C promoter, is expressed significantly more in brain, kidney and lung compared to heart and liver. A similar expression pattern was also seen for the endogenous rat APP. The unexpected similarity in the tissue-specific expression patterns of endogenous rat APP and transgenic human APP mRNAs suggests regulatory elements within the cDNA sequence of APP. Conclusion This manuscript describes the generation of APP-transgenic inbred Fischer 344 rats. These are the first human AD model rat lines generated by lentiviral infection. The APP21 rat line expresses high levels of human APP and could be a useful model for AD. Tissue

  15. Altered cell cycle-related gene expression in brain and lymphocytes from a transgenic mouse model of Alzheimer's disease [amyloid precursor protein/presenilin 1 (PS1)].

    Science.gov (United States)

    Esteras, Noemí; Bartolomé, Fernando; Alquézar, Carolina; Antequera, Desireé; Muñoz, Úrsula; Carro, Eva; Martín-Requero, Ángeles

    2012-09-01

    Cumulative evidence indicates that aberrant re-expression of many cell cycle-related proteins and inappropriate neuronal cell cycle control are critical events in Alzheimer's disease (AD) pathogenesis. Evidence of cell cycle activation in post-mitotic neurons has also been observed in murine models of AD, despite the fact that most of these mice do not show massive loss of neuronal bodies. Dysfunction of the cell cycle appears to affect cells other than neurons, as peripheral cells, such as lymphocytes and fibroblasts from patients with AD, show an altered response to mitogenic stimulation. We sought to determine whether cell cycle disturbances are present simultaneously in both brain and peripheral cells from the amyloid precursor protein (APP)/presenilin 1 (PS1) mouse model of AD, in order to validate the use of peripheral cells from patients not only to study cell cycle abnormalities as a pathogenic feature of AD, but also as a means to test novel therapeutic approaches. By using cell cycle pathway-specific RT(2)Profiler™ PCR Arrays, we detected changes in a number of cell cycle-related genes in brain as well as in lymphocytes from APP/PS1 mice. Moreover, we found enhanced 5'-bromo-2'-deoxyuridine incorporation into DNA in lymphocytes from APP/PS1 mice, and increased expression of the cell proliferation marker proliferating cell nuclear antigen (PCNA), and the cyclin-dependent kinase (CDK) inhibitor Cdkn2a, as detected by immunohistochemistry in cortical neurons of the APP/PS1 mice. Taken together, the cell cycle-related changes in brain and blood cells reported here support the mitosis failure hypothesis in AD and validate the use of peripheral cells as surrogate tissue to study the molecular basis of AD pathogenesis.

  16. Sequential NMR resonance assignment and structure determination of the Kunitz-type inhibitor domain of the Alzheimer's beta-amyloid precursor protein.

    Science.gov (United States)

    Heald, S L; Tilton, R F; Hammond, L J; Lee, A; Bayney, R M; Kamarck, M E; Ramabhadran, T V; Dreyer, R N; Davis, G; Unterbeck, A

    1991-10-29

    Certain precursor proteins (APP751 and APP770) of the amyloid beta-protein (AP) present in Alzheimer's disease contain a Kunitz-type serine protease inhibitor domain (APPI). In this study, the domain is obtained as a functional inhibitor through both recombinant (APPIr) and synthetic (APPIs) methodologies, and the solution structure of APPI is determined by 1H 2D NMR techniques. Complete sequence-specific resonance assignments (except for P13 and G37 NH) for both APPIr and APPIs are achieved using standard procedures. Ambiguities arising from degeneracies in the NMR resonances are resolved by varying sample conditions. Qualitative interpretation of short- and long-range NOEs reveals secondary structural features similar to those extensively documented by NMR for bovine pancreatic trypsin inhibitor (BPTI). A more rigorous interpretation of the NOESY spectra yields NOE-derived interresidue distance restraints which are used in conjunction with dynamic simulated annealing to generate a family of APPI structures. Within this family, the beta-sheet and helical regions are in good agreement with the crystal structure of BPTI, whereas portions of the protease-binding loops deviate from those in BPTI. These deviations are consistent with those recently described in the crystal structure of APPI (Hynes et al., 1990). Also supported in the NMR study is the hydrophobic patch in the protease-binding domain created by side chain-side chain NOE contacts between M17 and F34. In addition, the NMR spectra indicate that the rotation of the W21 ring in APPI is hindered, unlike Y21 in BPTI, showing a greater than 90% preference for one orientation in the hydrophobic groove.

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

    Institute of Scientific and Technical Information of China (English)

    Bo Jiang; Eryuan Liao; Liming Tan; Ruchun Dai; Zhijie Xiao

    2009-01-01

    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

  18. Mechanistic pharmacokinetic-pharmacodynamic modeling of BACE1 inhibition in monkeys: development of a predictive model for amyloid precursor protein processing.

    Science.gov (United States)

    Liu, Xingrong; Wong, Harvey; Scearce-Levie, Kimberly; Watts, Ryan J; Coraggio, Melis; Shin, Young G; Peng, Kun; Wildsmith, Kristin R; Atwal, Jasvinder K; Mango, Jason; Schauer, Stephen P; Regal, Kelly; Hunt, Kevin W; Thomas, Allen A; Siu, Michael; Lyssikatos, Joseph; Deshmukh, Gauri; Hop, Cornelis E C A

    2013-07-01

    This study was conducted to determine the pharmacokinetics (PK) and pharmacodynamics (PD) of two novel inhibitors of β-site amyloid precursor protein (APP)-cleaving enzyme (BACE1), GNE-629 [(4S,4a'S,10a'S)-2-amino-8'-(2-fluoropyridin-3-yl)-1-methyl-3',4',4a',10a'-tetrahydro-1'H-spiro[imidazole-4,10'-pyrano[4,3-b]chromen]-5(1H)-one] and GNE-892 [(R)-2-amino-1,3',3'-trimethyl-7'-(pyrimidin-5-yl)-3',4'-dihydro-2'H-spiro[imidazole-4,1'-naphthalen]-5(1H)-one], and to develop a PK-PD model to predict in vivo effects based solely on in vitro activity and PK. GNE-629 and GNE-892 concentrations and PD biomarkers including amyloid β (Aβ) in the plasma and cerebrospinal fluid (CSF), and secreted APPβ (sAPPβ) and secreted APPα (sAPPα) in the CSF were measured after a single oral administration of GNE-629 (100 mg/kg) or GNE-892 (30 or 100 mg/kg) in cynomolgus monkeys. A mechanistic PK-PD model was developed to simultaneously characterize the plasma Aβ and CSF Aβ, sAPPα, and sAPPβ using GNE-629 in vivo data. This model was used to predict the in vivo effects of GNE-892 after adjustments based on differences in in vitro cellular activity and PK. The PK-PD model estimated GNE-629 CSF and free plasma IC₅₀ of 0.0033 μM and 0.065 μM, respectively. These differences in CSF and free plasma IC₅₀ suggest that different mechanisms are involved in Aβ formation in these two compartments. The predicted in vivo effects for GNE-892 using the PK-PD model were consistent with the observed data. In conclusion, a PK-PD model was developed to mechanistically describe the effects of BACE1 inhibition on Aβ, sAPPβ, and sAPPα in the CSF, and Aβ in the plasma. This model can be used to prospectively predict in vivo effects of new BACE1 inhibitors using just their in vitro activity and PK data.

  19. Phosphorylation of amyloid precursor protein at threonine 668 is essential for its copper-responsive trafficking in SH-SY5Y neuroblastoma cells.

    Science.gov (United States)

    Acevedo, Karla M; Opazo, Carlos M; Norrish, David; Challis, Leesa M; Li, Qiao-Xin; White, Anthony R; Bush, Ashley I; Camakaris, James

    2014-04-18

    Amyloid precursor protein (APP) undergoes post-translational modification, including O- and N-glycosylation, ubiquitination, and phosphorylation as it traffics through the secretory pathway. We have previously reported that copper promotes a change in the cellular localization of APP. We now report that copper increases the phosphorylation of endogenous APP at threonine 668 (Thr-668) in SH-SY5Y neuronal cells. The level of APPT668-p (detected using a phospho-site-specific antibody) exhibited a copper-dependent increase. Using confocal microscopy imaging we demonstrate that the phospho-deficient mutant, Thr-668 to alanine (T668A), does not exhibit detectable copper-responsive APP trafficking. In contrast, mutating a serine to an alanine at residue 655 does not affect copper-responsive trafficking. We further investigated the importance of the Thr-668 residue in copper-responsive trafficking by treating SH-SY5Y cells with inhibitors for glycogen synthase kinase 3-β (GSK3β) and cyclin-dependent kinases (Cdk), the main kinases that phosphorylate APP at Thr-668 in neurons. Our results show that the GSK3β kinase inhibitors LiCl, SB 216763, and SB 415286 prevent copper-responsive APP trafficking. In contrast, the Cdk inhibitors Purvalanol A and B had no significant effect on copper-responsive trafficking in SH-SY5Y cells. In cultured primary hippocampal neurons, copper promoted APP re-localization to the axon, and this effect was inhibited by the addition of LiCl, indicating that a lithium-sensitive kinase(s) is involved in copper-responsive trafficking in hippocampal neurons. This is consistent with APP axonal transport to the synapse, where APP is involved in a number of functions. We conclude that copper promotes APP trafficking by promoting a GSK3β-dependent phosphorylation in SH-SY5Y cells.

  20. Increased secreted amyloid precursor protein-α (sAPPα in severe autism: proposal of a specific, anabolic pathway and putative biomarker.

    Directory of Open Access Journals (Sweden)

    Balmiki Ray

    Full Text Available Autism is a neurodevelopmental disorder characterized by deficits in verbal communication, social interactions, and the presence of repetitive, stereotyped and compulsive behaviors. Excessive early brain growth is found commonly in some patients and may contribute to disease phenotype. Reports of increased levels of brain-derived neurotrophic factor (BDNF and other neurotrophic-like factors in autistic neonates suggest that enhanced anabolic activity in CNS mediates this overgrowth effect. We have shown previously that in a subset of patients with severe autism and aggression, plasma levels of the secreted amyloid-β (Aβ precursor protein-alpha form (sAPPα were significantly elevated relative to controls and patients with mild-to-moderate autism. Here we further tested the hypothesis that levels of sAPPα and sAPPβ (proteolytic cleavage products of APP by α- and β-secretase, respectively are deranged in autism and may contribute to an anabolic environment leading to brain overgrowth. We measured plasma levels of sAPPα, sAPPβ, Aβ peptides and BDNF by corresponding ELISA in a well characterized set of subjects. We included for analysis 18 control, 6 mild-to-moderate, and 15 severely autistic patient plasma samples. We have observed that sAPPα levels are increased and BDNF levels decreased in the plasma of patients with severe autism as compared to controls. Further, we show that Aβ1-40, Aβ1-42, and sAPPβ levels are significantly decreased in the plasma of patients with severe autism. These findings do not extend to patients with mild-to-moderate autism, providing a biochemical correlate of phenotypic severity. Taken together, this study provides evidence that sAPPα levels are generally elevated in severe autism and suggests that these patients may have aberrant non-amyloidogenic processing of APP.

  1. Retromer Binds the FANSHY Sorting Motif in SorLA to Regulate Amyloid Precursor Protein Sorting and Processing

    DEFF Research Database (Denmark)

    Fjorback, Anja W; Seaman, Matthew; Gustafsen, Camilla;

    2012-01-01

    and levels of retromer proteins are altered in AD. Here we report that sorLA and retromer functionally interact in neurons to control trafficking and amyloidogenic processing of APP. We have identified a sequence (FANSHY) in the cytoplasmic domain of sorLA that is recognized by the VPS26 subunit...

  2. Porcine prion protein amyloid.

    Science.gov (United States)

    Hammarström, Per; Nyström, Sofie

    2015-01-01

    Mammalian prions are composed of misfolded aggregated prion protein (PrP) with amyloid-like features. Prions are zoonotic disease agents that infect a wide variety of mammalian species including humans. Mammals and by-products thereof which are frequently encountered in daily life are most important for human health. It is established that bovine prions (BSE) can infect humans while there is no such evidence for any other prion susceptible species in the human food chain (sheep, goat, elk, deer) and largely prion resistant species (pig) or susceptible and resistant pets (cat and dogs, respectively). PrPs from these species have been characterized using biochemistry, biophysics and neurobiology. Recently we studied PrPs from several mammals in vitro and found evidence for generic amyloidogenicity as well as cross-seeding fibril formation activity of all PrPs on the human PrP sequence regardless if the original species was resistant or susceptible to prion disease. Porcine PrP amyloidogenicity was among the studied. Experimentally inoculated pigs as well as transgenic mouse lines overexpressing porcine PrP have, in the past, been used to investigate the possibility of prion transmission in pigs. The pig is a species with extraordinarily wide use within human daily life with over a billion pigs harvested for human consumption each year. Here we discuss the possibility that the largely prion disease resistant pig can be a clinically silent carrier of replicating prions.

  3. The Golgi-Localized γ-Ear-Containing ARF-Binding (GGA Proteins Alter AmyloidPrecursor Protein (APP Processing through Interaction of Their GAE Domain with the Beta-Site APP Cleaving Enzyme 1 (BACE1.

    Directory of Open Access Journals (Sweden)

    Bjoern von Einem

    Full Text Available Proteolytic processing of amyloidprecursor protein (APP by beta-site APP cleaving enzyme 1 (BACE1 is the initial step in the production of amyloid beta (Aβ, which accumulates in senile plaques in Alzheimer's disease (AD. Essential for this cleavage is the transport and sorting of both proteins through endosomal/Golgi compartments. Golgi-localized γ-ear-containing ARF-binding (GGA proteins have striking cargo-sorting functions in these pathways. Recently, GGA1 and GGA3 were shown to interact with BACE1, to be expressed in neurons, and to be decreased in AD brain, whereas little is known about GGA2. Since GGA1 impacts Aβ generation by confining APP to the Golgi and perinuclear compartments, we tested whether all GGAs modulate BACE1 and APP transport and processing. We observed decreased levels of secreted APP alpha (sAPPα, sAPPβ, and Aβ upon GGA overexpression, which could be reverted by knockdown. GGA-BACE1 co-immunoprecipitation was impaired upon GGA-GAE but not VHS domain deletion. Autoinhibition of the GGA1-VHS domain was irrelevant for BACE1 interaction. Our data suggest that all three GGAs affect APP processing via the GGA-GAE domain.

  4. Repeated administration of the noradrenergic neurotoxin N-(2-chloroethyl-N-ethyl-2-bromobenzylamine (DSP-4 modulates neuroinflammation and amyloid plaque load in mice bearing amyloid precursor protein and presenilin-1 mutant transgenes

    Directory of Open Access Journals (Sweden)

    Richardson Jill C

    2007-02-01

    Full Text Available Abstract Background Data indicates anti-oxidant, anti-inflammatory and pro-cognitive properties of noradrenaline and analyses of post-mortem brain of Alzheimer's disease (AD patients reveal major neuronal loss in the noradrenergic locus coeruleus (LC, the main source of CNS noradrenaline (NA. The LC has projections to brain regions vulnerable to amyloid deposition and lack of LC derived NA could play a role in the progression of neuroinflammation in AD. Previous studies reveal that intraperitoneal (IP injection of the noradrenergic neurotoxin N-(2-chloroethyl-N-ethyl-2-bromobenzylamine (DSP-4 can modulate neuroinflammation in amyloid over-expressing mice and in one study, DSP-4 exacerbated existing neurodegeneration. Methods TASTPM mice over-express human APP and beta amyloid protein and show age related cognitive decline and neuroinflammation. In the present studies, 5 month old C57/BL6 and TASTPM mice were injected once monthly for 6 months with a low dose of DSP-4 (5 mg kg-1 or vehicle. At 8 and 11 months of age, mice were tested for cognitive ability and brains were examined for amyloid load and neuroinflammation. Results At 8 months of age there was no difference in LC tyrosine hydroxylase (TH across all groups and cortical NA levels of TASTPM/DSP-4, WT/Vehicle and WT/DSP-4 were similar. NA levels were lowest in TASTPM/Vehicle. Messenger ribonucleic acid (mRNA for various inflammatory markers were significantly increased in TASTPM/Vehicle compared with WT/Vehicle and by 8 months of age DSP-4 treatment modified this by reducing the levels of some of these markers in TASTPM. TASTPM/Vehicle showed increased astrocytosis and a significantly larger area of cortical amyloid plaque compared with TASTPM/DSP-4. However, by 11 months, NA levels were lowest in TASTPM/DSP-4 and there was a significant reduction in LC TH of TASTPM/DSP-4 only. Both TASTPM groups had comparable levels of amyloid, microglial activation and astrocytosis and mRNA for

  5. Amyloid Precursor Protein (APP) May Act as a Substrate and a Recognition Unit for CRL4CRBN and Stub1 E3 Ligases Facilitating Ubiquitination of Proteins Involved in Presynaptic Functions and Neurodegeneration.

    Science.gov (United States)

    Del Prete, Dolores; Rice, Richard C; Rajadhyaksha, Anjali M; D'Adamio, Luciano

    2016-08-12

    The amyloid precursor protein (APP), whose mutations cause Alzheimer disease, plays an important in vivo role and facilitates transmitter release. Because the APP cytosolic region (ACR) is essential for these functions, we have characterized its brain interactome. We found that the ACR interacts with proteins that regulate the ubiquitin-proteasome system, predominantly with the E3 ubiquitin-protein ligases Stub1, which binds the NH2 terminus of the ACR, and CRL4(CRBN), which is formed by Cul4a/b, Ddb1, and Crbn, and interacts with the COOH terminus of the ACR via Crbn. APP shares essential functions with APP-like protein-2 (APLP2) but not APP-like protein-1 (APLP1). Noteworthy, APLP2, but not APLP1, interacts with Stub1 and CRL4(CRBN), pointing to a functional pathway shared only by APP and APLP2. In vitro ubiquitination/ubiquitome analysis indicates that these E3 ligases are enzymatically active and ubiquitinate the ACR residues Lys(649/650/651/676/688) Deletion of Crbn reduces ubiquitination of Lys(676) suggesting that Lys(676) is physiologically ubiquitinated by CRL4(CRBN) The ACR facilitated in vitro ubiquitination of presynaptic proteins that regulate exocytosis, suggesting a mechanism by which APP tunes transmitter release. Other dementia-related proteins, namely Tau and apoE, interact with and are ubiquitinated via the ACR in vitro This, and the evidence that CRBN and CUL4B are linked to intellectual disability, prompts us to hypothesize a pathogenic mechanism, in which APP acts as a modulator of E3 ubiquitin-protein ligase(s), shared by distinct neuronal disorders. The well described accumulation of ubiquitinated protein inclusions in neurodegenerative diseases and the link between the ubiquitin-proteasome system and neurodegeneration make this concept plausible.

  6. 外源性H2S通过调节β-位淀粉样前体蛋白裂解酶1表达对PC12细胞APP/Ap代谢的影响%Effect of Exogenous Hydrogen Sulfide on Amyloid Precursor Protein/β-amyloid Processing Through Regulating Expression of β-site Amyloid Precursor Protein Cleaving Enzyme 1 in Pheochromocytoma Cells

    Institute of Scientific and Technical Information of China (English)

    代政伟; 孟涛; 晏勇

    2011-01-01

    目的 观察外源性硫化氮对啥格细胞瘤细胞p一位淀粉样前体蛋白裂解酶1(BACE1)的调节作用,进而探讨其对淀粉样前体蛋白/β-位淀粉样蛋白代谢途径的影响.方法 用硫氮化钠作外源性HZS供体,实脸设空白对照组、NaHS 50 μmol/L组、NaHS 100μmol/L组和NaHS 200 μmol/L组,按分组浓度处理PC12细胞24 h后,RT-PCR和Western blot法检测细胞内BACEI mRNA及蛋白表达,并用Western blot法继而检测APP代谢过程中关健蛋白APP,C99,C83表达变化,ELISA法检浏细胞培养液中Aβ40和Aβ42水平.结果 NaHS在实脸浓度范围内从基因与蛋白两个水平上呈剂量依赖性下调BACEI表达,并下调C99,Aβ40和Aβ42蛋白表达,上调C83蛋白,各NaHS组分别与对照组比校,差别均有统计学意义(P0.05).结论 外源性HZS具有通过调节PC12细胞BACEI表达下调APP/Ap代谢的作用.%Objective To observe the effect of exogenous hydrogen sulfide on β-site amyioid precursor protein cleaving enzyme 1 ( BACE1 ) and the amyloid precursor protein/β-amyloid (APP/Aβ) processing in pheochromocytoma (PC12) cells. Methods PC12 cells were divided into 4 groups:blank control group,NaHS 50 μmol/L group, NaHS100 μmol/L group and NaHS 200 .μmol/L group. Four groups were treated with 0,50,100 or 200 μmol/L sodium hydrosulfide( NaHS, the homer of exogenous hydrogen sulfide ), respectively. RT-PCR and Western blot were used to detect the levels of BACE1 mRNA and protein expression. Western blot was also used to detect the levels of key proteins in the metabolic process of APP,including APP,C99 and C83. ELISA method was used to analyze the levels of Aβ40 and Aβ42 in cellular culture medium. Results Compared with blank control group, NaHS significantly and dose-dependently decreased BACE1 mRNA and protein expression within experimental concentration rages in NaHS groups. So did the C99, Aβ40 and Aβ42 proteins( all P < 0. 05 ). On the contrary, C83 protein significantly increased

  7. Activation of the Wnt/β-catenin pathway represses the transcription of the β-amyloid precursor protein cleaving enzyme (BACE1) via binding of T-cell factor-4 to BACE1 promoter.

    Science.gov (United States)

    Parr, Callum; Mirzaei, Nazanin; Christian, Mark; Sastre, Magdalena

    2015-02-01

    Alterations in the Wnt signaling pathway have been implicated in Alzheimer's disease; however, its role in the processing of the amyloid precursor protein remains unknown. In this study, activation of the Wnt pathway by overexpression of the agonist Wnt3a or β-catenin or by inhibition of glycogen kinase synthase-3 in N2a cells resulted in a reduction in Aβ levels and in the activity and expression of BACE1 (β-APP cleaving enzyme). Conversely, inhibition of the pathway by transfection of the antagonists secreted frizzled receptor protein-1 or dickkopf-1 produced the opposite effects. Chromatin immunoprecipitation analysis demonstrated that β-catenin binds specifically to regions within the promoter of BACE1 containing putative T-cell factor/lymphoid enhancer binding factor-1 (TCF/LEF) motifs, consistent with canonical Wnt target regulation. Furthermore, cells transfected with β-catenin mutants incapable of binding to TCF/LEF increased BACE1 gene promoter activity. Interestingly, TCF4 knockdown reversed the effects of Wnt3a activation on BACE1 transcription. We found that TCF4 binds to the same region on BACE1 promoter following Wnt3a stimulation, indicating that TCF4 functions as a transcriptional repressor of BACE1 gene. In conclusion, Wnt/β-catenin stimulation may repress BACE1 transcription via binding of TCF4 to BACE1 gene, and therefore, activation of the Wnt pathway may hold the key to new treatments of Alzheimer disease.-Parr, C., Mirzaei, N., Christian, M., and Sastre, M. Activation of the Wnt/β-catenin pathway represses the transcription of the β-amyloid precursor protein cleaving enzyme (BACE1) via binding of T-cell factor-4 to BACE1 promoter.

  8. Effects of Gingko biloba leaf extract on learning, memory, and hippocampal amyloid precursor protein mRNA expressions in diabetic rats

    Institute of Scientific and Technical Information of China (English)

    Xiaofan Zhang; Bo Liang; Zhifeng Liang; Jun Lin

    2008-01-01

    BACKGROUND: The mechanisms of brain injury Following diabetes could be related to amyloid precursor protein (APP) mRNA overexpression. Studies have shown that Gingko biloba leaf extract (Egb) is effective in promoting functional recovery of the brain after traumatic injury. Egb is also effective in improving central nervous system plasticity and learning and memory functions of the elderly.OBJECTIVE: To study the effects of Egb on learning and memory, as well as hippocampal APP mRNA expression in the brains of diabetic rats, using Morris water maze behavioral testing and reverse transcription polymerase chain reaction (RT-PCR), respectively.DESIGN: Complete random design, controlled experimental study.SETTING: Department of Pharmacology, Pharmaceutical School, Guangxi Medical University.MATERIALS: A total of 70 male Wistar rats (180-220 g), 8 weeks old and specific pathogen free, were used for this study. GbE (containing 24.8% flavone glycosides and 6.2% diterpene lactone) was purchased from Guilin Sitejia Natural Plants Pharmaceutical Factory (Guangxi Province, Lot NO. 200405). Streptozotocin was purchased from Sigma (USA). Protamine zinc insulin injection was purchased from WANBANG Biochemical Pharmaceutical Co., Ltd. (Xuzhou Jiangsu, China).METHODS: The experiment was performed in the Experimental Center of Guangxi Medical University from March to October 2005. ① Experimental intervention: 70 rats were divided randomly into normal control group, diabetic model group (DM group), diabetic model +10 μg/kg insulin group (DM + Ins group), diabetic model + 100 mg/kg ginkgo leaf extract group (DM + Egb high-dose group), and diabetic model + 50 mg/kg ginkgo leaf extract group (DM + Egb low-dose group); there were 14 rats in each group. Rats with an intraperitoneal (I.p.) injection of citrate buffer solution (pH 4.4) served as the control group. To establish the diabetes model, rats were treated with I.p. Injection of 55 mg/kg streptozotocin. Insulin (10 U/kg) was

  9. PuF, an antimetastatic and developmental signaling protein, interacts with the Alzheimer’s amyloidprecursor protein via a tissue-specific proximal regulatory element (PRE

    Directory of Open Access Journals (Sweden)

    Lahiri Debomoy K

    2013-01-01

    Full Text Available Abstract Background Alzheimer’s disease (AD is intimately tied to amyloid-β (Aβ peptide. Extraneuronal brain plaques consisting primarily of Aβ aggregates are a hallmark of AD. Intraneuronal Aβ subunits are strongly implicated in disease progression. Protein sequence mutations of the Aβ precursor protein (APP account for a small proportion of AD cases, suggesting that regulation of the associated gene (APP may play a more important role in AD etiology. The APP promoter possesses a novel 30 nucleotide sequence, or “proximal regulatory element” (PRE, at −76/−47, from the +1 transcription start site that confers cell type specificity. This PRE contains sequences that make it vulnerable to epigenetic modification and may present a viable target for drug studies. We examined PRE-nuclear protein interaction by gel electrophoretic mobility shift assay (EMSA and PRE mutant EMSA. This was followed by functional studies of PRE mutant/reporter gene fusion clones. Results EMSA probed with the PRE showed DNA-protein interaction in multiple nuclear extracts and in human brain tissue nuclear extract in a tissue-type specific manner. We identified transcription factors that are likely to bind the PRE, using competition gel shift and gel supershift: Activator protein 2 (AP2, nm23 nucleoside diphosphate kinase/metastatic inhibitory protein (PuF, and specificity protein 1 (SP1. These sites crossed a known single nucleotide polymorphism (SNP. EMSA with PRE mutants and promoter/reporter clone transfection analysis further implicated PuF in cells and extracts. Functional assays of mutant/reporter clone transfections were evaluated by ELISA of reporter protein levels. EMSA and ELISA results correlated by meta-analysis. Conclusions We propose that PuF may regulate the APP gene promoter and that AD risk may be increased by interference with PuF regulation at the PRE. PuF is targeted by calcium/calmodulin-dependent protein kinase II inhibitor 1, which also

  10. Alcadein cleavages by amyloid beta-precursor protein (APP) alpha- and gamma-secretases generate small peptides, p3-Alcs, indicating Alzheimer disease-related gamma-secretase dysfunction.

    Science.gov (United States)

    Hata, Saori; Fujishige, Sayaka; Araki, Yoichi; Kato, Naoko; Araseki, Masahiko; Nishimura, Masaki; Hartmann, Dieter; Saftig, Paul; Fahrenholz, Falk; Taniguchi, Miyako; Urakami, Katsuya; Akatsu, Hiroyasu; Martins, Ralph N; Yamamoto, Kazuo; Maeda, Masahiro; Yamamoto, Tohru; Nakaya, Tadashi; Gandy, Sam; Suzuki, Toshiharu

    2009-12-25

    Alcadeins (Alcs) constitute a family of neuronal type I membrane proteins, designated Alc(alpha), Alc(beta), and Alc(gamma). The Alcs express in neurons dominantly and largely colocalize with the Alzheimer amyloid precursor protein (APP) in the brain. Alcs and APP show an identical function as a cargo receptor of kinesin-1. Moreover, proteolytic processing of Alc proteins appears highly similar to that of APP. We found that APP alpha-secretases ADAM 10 and ADAM 17 primarily cleave Alc proteins and trigger the subsequent secondary intramembranous cleavage of Alc C-terminal fragments by a presenilin-dependent gamma-secretase complex, thereby generating "APP p3-like" and non-aggregative Alc peptides (p3-Alcs). We determined the complete amino acid sequence of p3-Alc(alpha), p3-Alc(beta), and p3-Alc(gamma), whose major species comprise 35, 37, and 31 amino acids, respectively, in human cerebrospinal fluid. We demonstrate here that variant p3-Alc C termini are modulated by FAD-linked presenilin 1 mutations increasing minor beta-amyloid species Abeta42, and these mutations alter the level of minor p3-Alc species. However, the magnitudes of C-terminal alteration of p3-Alc(alpha), p3-Alc(beta), and p3-Alc(gamma) were not equivalent, suggesting that one type of gamma-secretase dysfunction does not appear in the phenotype equivalently in the cleavage of type I membrane proteins. Because these C-terminal alterations are detectable in human cerebrospinal fluid, the use of a substrate panel, including Alcs and APP, may be effective to detect gamma-secretase dysfunction in the prepathogenic state of Alzheimer disease subjects.

  11. Protein Polymers and Amyloids

    DEFF Research Database (Denmark)

    Risør, Michael Wulff

    2014-01-01

    , underlining the importance of understanding this relationship. The monomeric C-36 peptide was investigated by liquid-state NMR spectroscopy and found to be intrinsically disordered with minor propensities towards β-sheet structure. The plasticity of such a peptide makes it suitable for a whole range......, is a general hallmark. They also include the α1-antitrypsin deficiency, where disease-causing mutations in the serine protease inhibitor, α1-antitrypsin (α1AT), leads to accumulation of the aberrant protein in the liver of these patients. The native metastable structure of α1AT constitutes a molecular trap...... of this mechanism were investigated through a series of interaction experiments. Despite a very buried location in the native structure, evidence here suggest that the C-terminal tail is labile under slightly destabilizing conditions, providing new detail to this matter. A small infectious polymer unit was also...

  12. Janus faces of amyloid proteins in neuroinflammation.

    Science.gov (United States)

    Steinman, Lawrence; Rothbard, Jonathan B; Kurnellas, Michael P

    2014-07-01

    Amyloid forming molecules are generally considered harmful. In Alzheimer's Disease two amyloid molecules Aβ A4 and tau vie for consideration as the main pathogenic culprit. But molecules obey the laws of chemistry and defy the way we categorize them as humans with our well-known proclivities to bias in our reasoning. We have been exploring the brains of multiple sclerosis patients to identify molecules that are associated with protection from inflammation and degeneration. In 2001 we noted that aB crystallin (cryab) was the most abundant transcript found in MS lesions, but not in healthy brains. Cryab can reverse paralysis and attenuate inflammation in several models of inflammation including experimental autoimmune encephalomyelitis (EAE), and various models of ischemia. Cryab is an amyloid forming molecule. We have identified a core structure common to many amyloids including amyloid protein Aβ A4, tau, amylin, prion protein, serum amyloid protein P, and cryab. The core hexapeptide structure is highly immune suppressive and can reverse paralysis in EAE when administered systemically. Administration of this amyloid forming hexapeptide quickly lowers inflammatory cytokines in plasma like IL-6 and IL-2. The hexapeptide bind a set of proinflammatory mediators in plasma, including acute phase reactants and complement components. The beneficial properties of amyloid forming hexapeptides provide a potential new therapeutic direction. These experiments indicate that amyloid forming molecules have Janus faces, providing unexpected benefit for neuroinflammatory conditions.

  13. ApoER2 expression increases Aβ production while decreasing Amyloid Precursor Protein (APP endocytosis: Possible role in the partitioning of APP into lipid rafts and in the regulation of γ-secretase activity

    Directory of Open Access Journals (Sweden)

    Bu Guojun

    2007-07-01

    Full Text Available Abstract Background The generation of the amyloid-β peptide (Aβ through the proteolytic processing of the amyloid precursor protein (APP is a central event in the pathogenesis of Alzheimer's disease (AD. Recent studies highlight APP endocytosis and localization to lipid rafts as important events favoring amyloidogenic processing. However, the precise mechanisms underlying these events are poorly understood. ApoER2 is a member of the low density lipoprotein receptor (LDL-R family exhibiting slow endocytosis rate and a significant association with lipid rafts. Despite the important neurophysiological roles described for ApoER2, little is known regarding how ApoER2 regulates APP trafficking and processing. Results Here, we demonstrate that ApoER2 physically interacts and co-localizes with APP. Remarkably, we found that ApoER2 increases cell surface APP levels and APP association with lipid rafts. The increase of cell surface APP requires the presence of ApoER2 cytoplasmic domain and is a result of decreased APP internalization rate. Unexpectedly, ApoER2 expression correlated with a significant increase in Aβ production and reduced levels of APP-CTFs. The increased Aβ production was dependent on the integrity of the NPxY endocytosis motif of ApoER2. We also found that expression of ApoER2 increased APP association with lipid rafts and increased γ-secretase activity, both of which might contribute to increased Aβ production. Conclusion These findings show that ApoER2 negatively affects APP internalization. However, ApoER2 expression stimulates Aβ production by shifting the proportion of APP from the non-rafts to the raft membrane domains, thereby promoting β-secretase and γ-secretase mediated amyloidogenic processing and also by incrementing the activity of γ-secretase.

  14. Repeated administration of the noradrenergic neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) modulates neuroinflammation and amyloid plaque load in mice bearing amyloid precursor protein and presenilin-1 mutant transgenes

    OpenAIRE

    Richardson Jill C; Virley David J; Babin Anna; Bate Simon T; Joyce Flora; Perren Marion J; Seymour Zoe; Culbert Ainsley A; Ashmeade Tracey; Vidgeon-Hart Martin P; Pugh Perdita L; Upton Neil; Sunter David

    2007-01-01

    Abstract Background Data indicates anti-oxidant, anti-inflammatory and pro-cognitive properties of noradrenaline and analyses of post-mortem brain of Alzheimer's disease (AD) patients reveal major neuronal loss in the noradrenergic locus coeruleus (LC), the main source of CNS noradrenaline (NA). The LC has projections to brain regions vulnerable to amyloid deposition and lack of LC derived NA could play a role in the progression of neuroinflammation in AD. Previous studies reveal that intrape...

  15. Luteolin Isolated from the Medicinal Plant Elsholtzia rugulosa (Labiatae Prevents Copper-Mediated Toxicity in β-Amyloid Precursor Protein Swedish Mutation Overexpressing SH-SY5Y Cells

    Directory of Open Access Journals (Sweden)

    Guanhua Du

    2011-03-01

    Full Text Available Luteolin, a 3’,4’,5,7-tetrahydroxyflavone, is a plant flavonoid and pharmacologically active agent that has been isolated from several plant species. In the present study, the effects of luteolin obtained from the medicinal plant Elsholtzia rugulosa and the related mechanisms were examined in an Alzheimer's disease (AD cell model. In this model, copper was used to exacerbate the neurotoxicity in β-amyloid precursor protein Swedish mutation stably overexpressed SH-SY5Y cells (named “APPsw cells” for short. Based on this model, we demonstrated that luteolin increased cell viability, reduced intracellular ROS generation, enhanced the activity of SOD and reversed mitochondrial membrane potential dissipation. Inhibition of caspase-related apoptosis was consistently involved in the neuroprotection afforded by luteolin. Furthermore, it down-regulated the expression of AβPP and lowered the secretion of Aβ1-42. These results indicated that luteolin from the Elsholtzia rugulosa exerted neroprotective effects through mechanisms that decrease AβPP expression, lower Aβ secretion, regulate the redox imbalance, preserve mitochondrial function, and depress the caspase family-related apoptosis.

  16. Oncogene K-Ras Affects the Processing of Amyloid Precursor Protein (APP) Through Regulating Its Phosphorylation at Thr668%原癌基因K-Ras调控APPThr668位点磷酸化及APP的切割

    Institute of Scientific and Technical Information of China (English)

    刘杨; 杨龙雨; 谢勇壮; 张弦; 许华曦; 张云武

    2012-01-01

    The expression of Ras is elevated during early stages of Alzheimer's disease. Here we investigated the effect of K-Ras on the processing of amyloid precursor protein (APP). The results showed that overexpression of K-Ras and its constitutively active mutant K-RasG12V could activate ERK1/2 and JNK pathways and induced phosphorylation of APP at"ftr668. While inhibition of the JNK pathway blocked the phosphorylation of APP. In addition, overexpression of K-Ras reduced the levels of sAPPf) and increased the levels of sAPPa but had no effect on the levels of AD AMI 0 and BACE1. Through biptin labeling experiment, we demonstrated that overexpression of K-Ras increased cell surface levels of APP without affecting the levels of tptal APP. Together, these results suggest that K-Ras can regulate APP phosphorylation and APP trafficking for its processing through the JNK pathway, implying that K-Ras may be a new target/pathway for regulating AD pathologies.%在阿尔茨海默症(Alzheimer's disease,AD)发病的早期,Ras蛋白所在的信号通路被激活,但具体作用机制还不清楚.探讨了K-Ras及其突变体K-RasG12V对淀粉样前体蛋白(amyloid precursor protein,APP)的剪切的影响.Western blot结果显示,过量表达K-Ras能够激活细胞外调节蛋白激酶1/2(extracellular signal-regulated kinase,ERK 1/2)、c-Jun氨基末端激酶(c-Jun N-terminal kinase,JNK)通路,并增加APP在Thr668的磷酸化;抑制JNK通路则阻断了K-Ras过表达所引起的APP Thr668磷酸化.此外,过表达K-Ras造成分泌到细胞外的sAPPα增加,而sAPPβ减少.通过生物素标记实验发现,过表达K-Ras使得APP在细胞膜上的定位增加,而细胞内APP总量没有改变.这些结果表明,过量表达K-Ras可以通过调控JNK的通路,增加APP在Thr668位点的磷酸化,造成APP在细胞膜上水平升高,导致APP向sAPPβ的切割减少,而向sAPPα的切割增加.提示K-Ras对APP切割的影响可能在AD的发病过程中起着一定的应激作用.

  17. Alternative Selection of β-Site APP-Cleaving Enzyme 1 (BACE1) Cleavage Sites in Amyloid β-Protein Precursor (APP) Harboring Protective and Pathogenic Mutations within the Aβ Sequence.

    Science.gov (United States)

    Kimura, Ayano; Hata, Saori; Suzuki, Toshiharu

    2016-11-11

    β-Site APP-cleaving enzyme 1 (BACE1) cleaves amyloid β-protein precursor (APP) at the bond between Met(671) and Asp(672) (β-site) to generate the carboxyl-terminal fragment (CTFβ/C99). BACE1 also cleaves APP at another bond between Thr(681) and Gln(682) (β'-site), yielding CTFβ'/C89. Cleavage of CTFβ/C99 by γ-secretase generates Aβ(1-XX), whereas cleavage of CTFβ'/C89 generates Aβ(11-XX). Thus, β'-site cleavage by BACE1 is amyloidolytic rather than amyloidogenic. β' cleavage of mouse APP is more common than the corresponding cleavage of human APP. We found that the H684R substitution within human Aβ, which replaces the histidine in the human protein with the arginine found at the corresponding position in mouse, facilitated β' cleavage irrespective of the species origin of BACE1, thereby significantly increasing the level of Aβ(11-XX) and decreasing the level of Aβ(1-XX). Thus, amino acid substitutions within the Aβ sequence influenced the selectivity of alternative β- or β'-site cleavage of APP by BACE1. In familial Alzheimer's disease (FAD), the APP gene harbors pathogenic variations such as the Swedish (K670N/M671L), Leuven (E682K), and A673V mutations, all of which decrease Aβ(11-40) generation, whereas the protective Icelandic mutation (A673T) increases generation of Aβ(11-40). Thus, A673T promotes β' cleavage of APP and protects subjects against AD. In addition, CTFβ/C99 was cleaved by excess BACE1 activity to generate CTFβ'/C89, followed by Aβ(11-40), even if APP harbored pathogenic mutations. The resultant Aβ(11-40) was more metabolically labile in vivo than Aβ(1-40). Our analysis suggests that some FAD mutations in APP are amyloidogenic and/or amyloidolytic via selection of alternative BACE1 cleavage sites.

  18. Serum amyloid A: an acute phase apolipoprotein and precursor of AA amyloid.

    Science.gov (United States)

    Marhaug, G; Dowton, S B

    1994-08-01

    Serum amyloid A is an acute phase protein complexed to HDL as an apoprotein. The molecular weight is 11.4-12.5 kDa in different species and the protein has from 104 to 112 amino acids, without or with an insertion of eight amino acids at position 72. The protein is very well conserved throughout evolution, indicating an important biological function. The N-terminal part of the molecule is hydrophobic and probably responsible for the lipid binding properties. The most conserved part is from position 38 to 52 and this part is therefore believed to be responsible for the until now unknown biological function. The protein is coded on chromosome 11p in man, and chromosome 7 in mice, and found in all mammals until now investigated, and also in the Peking duck. In the rat a truncated SAA mRNA has been demonstrated, but no equivalent serum protein has been reported. Acute phase SAA is first of all produced in hepatocytes after induction by cytokines, but extrahepatic expression of both acute phase and constitutive SAA proteins have been demonstrated. Several cytokines, first of all IL-1, IL-6 and TNF are involved in the induction of SAA synthesis, but the mutual importance of these cytokines seems to be cell-type specific and to vary in various experimental settings. The role of corticosteroids in SAA induction is somewhat confusing. In most in vitro studies corticosteroids show an enhancing or synergistic effect with cytokines on SAA production in cultured cell. However, in clinical studies and in vivo studies in animals an inhibitory effect of corticosteroids is evident, probably due to the all over anti-inflammatory effect of the drug. Until now no drug has been found that selectively inhibits SAA production by hepatocytes. Effective anti-inflammatory or antibacterial treatment is the only tool for reducing SAA concentration in serum and reducing the risk of developing secondary amyloidosis. The function of SAA is still unclear. Interesting theories, based on current

  19. Protein misfolding, congophilia, oligomerization, and defective amyloid processing in preeclampsia.

    Science.gov (United States)

    Buhimschi, Irina A; Nayeri, Unzila A; Zhao, Guomao; Shook, Lydia L; Pensalfini, Anna; Funai, Edmund F; Bernstein, Ira M; Glabe, Charles G; Buhimschi, Catalin S

    2014-07-16

    Preeclampsia is a pregnancy-specific disorder of unknown etiology and a leading contributor to maternal and perinatal morbidity and mortality worldwide. Because there is no cure other than delivery, preeclampsia is the leading cause of iatrogenic preterm birth. We show that preeclampsia shares pathophysiologic features with recognized protein misfolding disorders. These features include urine congophilia (affinity for the amyloidophilic dye Congo red), affinity for conformational state-dependent antibodies, and dysregulation of prototype proteolytic enzymes involved in amyloid precursor protein (APP) processing. Assessment of global protein misfolding load in pregnancy based on urine congophilia (Congo red dot test) carries diagnostic and prognostic potential for preeclampsia. We used conformational state-dependent antibodies to demonstrate the presence of generic supramolecular assemblies (prefibrillar oligomers and annular protofibrils), which vary in quantitative and qualitative representation with preeclampsia severity. In the first attempt to characterize the preeclampsia misfoldome, we report that the urine congophilic material includes proteoforms of ceruloplasmin, immunoglobulin free light chains, SERPINA1, albumin, interferon-inducible protein 6-16, and Alzheimer's β-amyloid. The human placenta abundantly expresses APP along with prototype APP-processing enzymes, of which the α-secretase ADAM10, the β-secretases BACE1 and BACE2, and the γ-secretase presenilin-1 were all up-regulated in preeclampsia. The presence of β-amyloid aggregates in placentas of women with preeclampsia and fetal growth restriction further supports the notion that this condition should join the growing list of protein conformational disorders. If these aggregates play a pathophysiologic role, our findings may lead to treatment for preeclampsia.

  20. Contrasting effects of nanoparticle-protein attraction on amyloid aggregation.

    Science.gov (United States)

    Radic, Slaven; Davis, Thomas P; Ke, Pu Chun; Ding, Feng

    2015-01-01

    Nanoparticles (NPs) have been experimentally found to either promote or inhibit amyloid aggregation of proteins, but the molecular mechanisms for such complex behaviors remain unknown. Using coarse-grained molecular dynamics simulations, we investigated the effects of varying the strength of nonspecific NP-protein attraction on amyloid aggregation of a model protein, the amyloid-beta peptide implicated in Alzheimer's disease. Specifically, with increasing NP-peptide attraction, amyloid aggregation on the NP surface was initially promoted due to increased local protein concentration on the surface and destabilization of the folded state. However, further increase of NP-peptide attraction decreased the stability of amyloid fibrils and reduced their lateral diffusion on the NP surface necessary for peptide conformational changes and self-association, thus prohibiting amyloid aggregation. Moreover, we found that the relative concentration between protein and NPs also played an important role in amyloid aggregation. With a high NP/protein ratio, NPs that intrinsically promote protein aggregation may display an inhibitive effect by depleting the proteins in solution while having a low concentration of the proteins on each NP's surface. Our coarse-grained molecular dynamics simulation study offers a molecular mechanism for delineating the contrasting and seemingly conflicting effects of NP-protein attraction on amyloid aggregation and highlights the potential of tailoring anti-aggregation nanomedicine against amyloid diseases.

  1. Amyloid β-sheet mimics that antagonize protein aggregation and reduce amyloid toxicity

    Science.gov (United States)

    Cheng, Pin-Nan; Liu, Cong; Zhao, Minglei; Eisenberg, David; Nowick, James S.

    2012-11-01

    The amyloid protein aggregation associated with diseases such as Alzheimer's, Parkinson's and type II diabetes (among many others) features a bewildering variety of β-sheet-rich structures in transition from native proteins to ordered oligomers and fibres. The variation in the amino-acid sequences of the β-structures presents a challenge to developing a model system of β-sheets for the study of various amyloid aggregates. Here, we introduce a family of robust β-sheet macrocycles that can serve as a platform to display a variety of heptapeptide sequences from different amyloid proteins. We have tailored these amyloid β-sheet mimics (ABSMs) to antagonize the aggregation of various amyloid proteins, thereby reducing the toxicity of amyloid aggregates. We describe the structures and inhibitory properties of ABSMs containing amyloidogenic peptides from the amyloid-β peptide associated with Alzheimer's disease, β2-microglobulin associated with dialysis-related amyloidosis, α-synuclein associated with Parkinson's disease, islet amyloid polypeptide associated with type II diabetes, human and yeast prion proteins, and Tau, which forms neurofibrillary tangles.

  2. Evaluación de la expresión de la proteína precursora de amiloide en células sanguíneas de pacientes con la mutación E280A en el gen de la presenilina 1 Alzheimer disease amyloid precursor protein e280a mutation flow cytometry presenilin

    Directory of Open Access Journals (Sweden)

    Francisco Lopera Restrepo

    2005-01-01

    development of an aggressive form of familial Alzheimer's disease. In order to define the role of such mutation on the expression of Amyloid Precursor Protein in peripheral blood mononuclear cells and B lymphocytes we carried out a study in three groups of people, namely: healthy carriers of the mutation, affected carriers and healthy non-carriers as controls. Flow cytometry was used for the detection of Amyloid Presursor Protein in cell membranes and intracellulary; HeLa and CHO cells were used as positive controls. Expression level of Amyloid Precursor Protein was higher in the intracellular compartment than in the cell membrane. The levels of expression in the intracellular compartment of HeLa and CHO cells were variable in contrast with those of peripheral blood mononuclear cells in which they were lower but stable. Contrariwise to the results of other authors, who have detected higher levels of Amyloid Precursor Protein in Alzheimer's disease patients, our results revealed no difference between healthy controls and carriers of the E280A mutation in the presenilin-1 gene, either diseased or healthy. Our results show that this mutation does not directly change the expression of Amyloid Precursor Protein in peripheral blood mononuclear cells.

  3. Unraveling the mystery of protein-amyloid binding mechanisms

    NARCIS (Netherlands)

    Beringer, D.

    2013-01-01

    There are several diseases which are caused by amyloid, a deposit of aggregated protein. Examples of these diseases are Alzheimer’s disease, caused by the aggregation of the peptide Aβ, and Diabetes type 2, caused by hIAPP aggregates. A large number of proteins interact with these amyloid fibrils, s

  4. The amyloid stretch hypothesis: Recruiting proteins toward the dark side

    Science.gov (United States)

    Esteras-Chopo, Alexandra; Serrano, Luis; de la Paz, Manuela López

    2005-01-01

    A detailed understanding of the molecular events underlying the conversion and self-association of normally soluble proteins into amyloid fibrils is fundamental to the identification of therapeutic strategies to prevent or cure amyloid-related disorders. Recent investigations indicate that amyloid fibril formation is not just a general property of the polypeptide backbone depending on external factors, but that it is strongly modulated by amino acid side chains. Here, we propose and address the validation of the premise that the amyloidogenicity of a protein is indeed localized in short protein stretches (amyloid stretch hypothesis). We demonstrate that the conversion of a soluble nonamyloidogenic protein into an amyloidogenic prone molecule can be triggered by a nondestabilizing six-residue amyloidogenic insertion in a particular structural environment. Interestingly enough, although the inserted amyloid sequences clearly cause the process, the protease-resistant core of the fiber also includes short adjacent sequences from the otherwise soluble globular domain. Thus, short amyloid stretches accessible for intermolecular interactions trigger the self-assembly reaction and pull the rest of the protein into the fibrillar aggregate. The reliable identification of such amyloidogenic stretches in proteins opens the possibility of using them as targets for the inhibition of the amyloid fibril formation process. PMID:16263932

  5. Amyloid-like protein inclusions in tobacco transgenic plants.

    Directory of Open Access Journals (Sweden)

    Anna Villar-Piqué

    Full Text Available The formation of insoluble protein deposits in human tissues is linked to the onset of more than 40 different disorders, ranging from dementia to diabetes. In these diseases, the proteins usually self-assemble into ordered β-sheet enriched aggregates known as amyloid fibrils. Here we study the structure of the inclusions formed by maize transglutaminase (TGZ in the chloroplasts of tobacco transplastomic plants and demonstrate that they have an amyloid-like nature. Together with the evidence of amyloid structures in bacteria and fungi our data argue that amyloid formation is likely a ubiquitous process occurring across the different kingdoms of life. The discovery of amyloid conformations inside inclusions of genetically modified plants might have implications regarding their use for human applications.

  6. SERF Protein Is a Direct Modifier of Amyloid Fiber Assembly

    Directory of Open Access Journals (Sweden)

    S. Fabio Falsone

    2012-08-01

    Full Text Available The inherent cytotoxicity of aberrantly folded protein aggregates contributes substantially to the pathogenesis of amyloid diseases. It was recently shown that a class of evolutionary conserved proteins, called MOAG-4/SERF, profoundly alter amyloid toxicity via an autonomous but yet unexplained mode. We show that the biological function of human SERF1a originates from its atypical ability to specifically distinguish between amyloid and nonamyloid aggregation. This inherently unstructured protein directly affected the aggregation kinetics of a broad range of amyloidogenic proteins in vitro, while being inactive against nonamyloid aggregation. A representative biophysical analysis of the SERF1a:α-synuclein (aSyn complex revealed that the amyloid-promoting activity resulted from an early and transient interaction, which was sufficient to provoke a massive increase of soluble aSyn amyloid nucleation templates. Therefore, the autonomous amyloid-modifying activity of SERF1a observed in living organisms relies on a direct and dedicated manipulation of the early stages in the amyloid aggregation pathway.

  7. Hitchhiking vesicular transport routes to the vacuole: amyloid recruitment to the Insoluble Protein Deposit (IPOD).

    Science.gov (United States)

    Kumar, Rajesh; Neuser, Nicole; Tyedmers, Jens

    2017-03-09

    Sequestration of aggregates into specialized deposition sites occurs in many species across all kingdoms of life ranging from bacteria to mammals and is commonly believed to have a cytoprotective function. Yeast cells possess at least three different spatially separated deposition sites, one of which is termed "Insoluble Protein Deposit (IPOD)" and harbors amyloid aggregates. We have recently discovered that recruitment of amyloid aggregates to the IPOD employs an actin cable based recruitment machinery that also involves vesicular transport (1) . Here we discuss how different proteins known to be involved in vesicular transport processes to the vacuole might act to guide amyloid aggregates to the IPOD. These factors include the Myosin V motor protein Myo2 involved in transporting vacuolar vesicles along actin cables, the transmembrane protein Atg9 involved in the recruitment of large precursor hydrolase complexes to the vacuole, the phosphatidylinositol/ phosphatidylcholine (PI/PC) transfer protein Sec 14 and the SNARE chaperone Sec 18. Furthermore, we present new data suggesting that the yeast dynamin homolog Vps1 is also crucial for faithful delivery of the amyloid model protein PrD-GFP to the IPOD. This is in agreement with a previously identified role for Vps1 in recruitment of heat-denatured aggregates to a perivacuolar deposition site (2) .

  8. A comparison of immunohistochemistry and mass spectrometry for determining the amyloid fibril protein from formalin-fixed biopsy tissue.

    Science.gov (United States)

    Gilbertson, Janet A; Theis, Jason D; Vrana, Julie A; Lachmann, Helen; Wechalekar, Ashutosh; Whelan, Carol; Hawkins, Philip N; Dogan, Ahmet; Gillmore, Julian D

    2015-04-01

    Amyloidosis is caused by deposition in tissues of abnormal protein in a characteristic fibrillar form. There are many types of amyloidosis, classified according to the soluble protein precursor from which the amyloid fibrils are derived. Accurate identification of amyloid type is critical in every case since therapy for systemic amyloidosis is type specific. In ∼20-25% cases, however, immunohistochemistry (IHC) fails to prove the amyloid type and further tests are required. Laser microdissection and mass spectrometry (LDMS) is a powerful tool for identifying proteins from formalin-fixed paraffin-embedded tissues. We undertook a blinded comparison of IHC, performed at the UK National Amyloidosis Centre, and LDMS, performed at the Mayo Clinic, in 142 consecutive biopsy specimens from 38 different tissue types. There was 100% concordance between positive IHC and LDMS, and the latter increased diagnostic accuracy from 76% to 94%. LDMS in expert hands is a valuable tool for amyloid diagnosis.

  9. Amyloid diseases of yeast: prions are proteins acting as genes.

    Science.gov (United States)

    Wickner, Reed B; Edskes, Herman K; Bateman, David A; Kelly, Amy C; Gorkovskiy, Anton; Dayani, Yaron; Zhou, Albert

    2014-01-01

    The unusual genetic properties of the non-chromosomal genetic elements [URE3] and [PSI+] led to them being identified as prions (infectious proteins) of Ure2p and Sup35p respectively. Ure2p and Sup35p, and now several other proteins, can form amyloid, a linear ordered polymer of protein monomers, with a part of each molecule, the prion domain, forming the core of this β-sheet structure. Amyloid filaments passed to a new cell seed the conversion of the normal form of the protein into the same amyloid form. The cell's phenotype is affected, usually from the deficiency of the normal form of the protein. Solid-state NMR studies indicate that the yeast prion amyloids are in-register parallel β-sheet structures, in which each residue (e.g. Asn35) forms a row along the filament long axis. The favourable interactions possible for aligned identical hydrophilic and hydrophobic residues are believed to be the mechanism for propagation of amyloid conformation. Thus, just as DNA mediates inheritance by templating its own sequence, these proteins act as genes by templating their conformation. Distinct isolates of a given prion have different biological properties, presumably determined by differences between the amyloid structures. Many lines of evidence indicate that the Saccharomyces cerevisiae prions are pathological disease agents, although the example of the [Het-s] prion of Podospora anserina shows that a prion can have beneficial aspects.

  10. MicroRNA-339-5p down-regulates protein expression of β-site amyloid precursor protein-cleaving enzyme 1 (BACE1) in human primary brain cultures and is reduced in brain tissue specimens of Alzheimer disease subjects.

    Science.gov (United States)

    Long, Justin M; Ray, Balmiki; Lahiri, Debomoy K

    2014-02-21

    Alzheimer disease (AD) results, in part, from the excess accumulation of the amyloid-β (Aβ) peptide as neuritic plaques in the brain. The short Aβ peptide is derived from the large transmembrane Aβ precursor protein (APP). The rate-limiting step in the production of Aβ from APP is mediated by the β-site APP-cleaving enzyme 1 (BACE1). Dysregulation of BACE1 levels leading to excess Aβ deposition is implicated in sporadic AD. Thus, elucidating the full complement of regulatory pathways that control BACE1 expression is key to identifying novel drug targets central to the Aβ-generating process. MicroRNAs (miRNAs) are expected to participate in this molecular network. Here, we identified a known miRNA, miR-339-5p, as a key contributor to this regulatory network. Two distinct miR-339-5p target sites were predicted in the BACE1 3'-UTR by in silico analyses. Co-transfection of miR-339-5p with a BACE1 3'-UTR reporter construct resulted in significant reduction in reporter expression. Mutation of both target sites eliminated this effect. Delivery of the miR-339-5p mimic also significantly inhibited expression of BACE1 protein in human glioblastoma cells and human primary brain cultures. Delivery of target protectors designed against the miR-339-5p BACE1 3'-UTR target sites in primary human brain cultures significantly elevated BACE1 expression. Finally, miR-339-5p levels were found to be significantly reduced in brain specimens isolated from AD patients as compared with age-matched controls. Therefore, miR-339-5p regulates BACE1 expression in human brain cells and is most likely dysregulated in at least a subset of AD patients making this miRNA a novel drug target.

  11. Milk proteins as precursors of bioactive peptides

    Directory of Open Access Journals (Sweden)

    Marta Dziuba

    2009-03-01

    Full Text Available Milk proteins, a source of bioactive peptides, are the subject of numerous research studies aiming to, among others, evaluate their properties as precursors of biologically active peptides. Physiologically active peptides released from their precursors may interact with selected receptors and affect the overall condition and health of humans. By relying on the BIOPEP database of proteins and bioactive peptides, developed by the Department of Food Biochemistry at the University of Warmia and Mazury in Olsztyn (www.uwm.edu.pl/biochemia, the profiles of potential activity of milk proteins were determined and the function of those proteins as bioactive peptide precursors was evaluated based on a quantitative criterion, i.e. the occurrence frequency of bioactive fragments (A. The study revealed that milk proteins are mainly a source of peptides with the following types of activity: antihypertensive (Amax = 0.225, immunomodulating (0.024, smooth muscle contracting (0.011, antioxidative (0.029, dipeptidyl peptidase IV inhibitors (0.148, opioid (0.073, opioid antagonistic (0.053, bonding and transporting metals and metal ions (0.024, antibacterial and antiviral (0.024, and antithrombotic (0.029. The enzymes capable of releasing bioactive peptides from precursor proteins were determined for every type of activity. The results of the experiment indicate that milk proteins such as lactoferrin, α-lactalbumin, β-casein and κ-casein hydrolysed by trypsin can be a relatively abundant source of biologically active peptides.

  12. Analysis of the role of the gene coding the Amyloid-Precursor Protein Binding Protein 1 (APP-BP1) in the radio-sensitivity of epidermoid carcinomas of the upper aero-digestive tract infected by the human papillomavirus; Analyse du role du gene codant l'Amyloid-Precursor Protein Binding Protein 1 (APP-BP1) dans la radiosensibilite des carcinomes epidermoides des voies aero-digestives superieures infectees par le papillomavirus humain

    Energy Technology Data Exchange (ETDEWEB)

    Guihard, S.; Altmeyer, A.; Ramolu, L.; Macabre, C.; Abecassis, J.; Noel, G.; Jung, A.C. [Centre de lutte contre le cancer Paul-Strauss, 67 - Strasbourg (France)

    2010-10-15

    As the human papillomavirus (HPV) is at the origin of 25% of upper aero-digestive tract cancers, and as these tumours present an increased radio-sensitivity compared to other tumours, probably due to a greater transcriptional activity of p53, the authors report the study on the influence of a decrease of the expression of the APP-BP1 in these tumours which could favour a radio-induced apoptosis. By using a reverse transcriptase polymerase chain reaction (RT-PCR), they assessed the APP-BP1 expression levels as well as expression levels of transcriptions coding onco-proteins known to be over-expressed in HPV+ tumours. They compared the radio-sensitivities of HPV+ and HPV- cells, the first one appearing to be greater than the second one. Short communication

  13. Amyloid beta-protein and lipid rafts: focused on biogenesis and catabolism.

    Science.gov (United States)

    Araki, Wataru; Tamaoka, Akira

    2015-01-01

    Cerebral accumulation of amyloid β-protein (Aβ) is thought to play a key role in the molecular pathology of Alzheimer's disease (AD). Three secretases (β-, γ-, and α-secretase) are proteases that control the production of Aβ from amyloid precursor protein. Increasing evidence suggests that cholesterol-rich membrane microdomains termed 'lipid rafts' are involved in the biogenesis and accumulation of Aβ as well as Aβ-mediated neurotoxicity. γ-Secretase is enriched in lipid rafts, which are considered an important site for Aβ generation. Additionally, Aβ-degrading peptidases located in lipid rafts, such as neprilysin, appear to play a role in Aβ catabolism. This mini-review focuses on the roles of lipid rafts in the biogenesis and catabolism of Aβ, covering recent research on the relationship between lipid rafts and the three secretases or Aβ-degrading peptidases. Furthermore, the significance of lipid rafts in Aβ aggregation and neurotoxicity is briefly summarized.

  14. The Components of Flemingia macrophylla Attenuate Amyloid β-Protein Accumulation by Regulating Amyloid β-Protein Metabolic Pathway

    Directory of Open Access Journals (Sweden)

    Yun-Lian Lin

    2012-01-01

    Full Text Available Flemingia macrophylla (Leguminosae is a popular traditional remedy used in Taiwan as anti-inflammatory, promoting blood circulation and antidiabetes agent. Recent study also suggested its neuroprotective activity against Alzheimer's disease. Therefore, the effects of F. macrophylla on Aβ production and degradation were studied. The effect of F. macrophylla on Aβ metabolism was detected using the cultured mouse neuroblastoma cells N2a transfected with human Swedish mutant APP (swAPP-N2a cells. The effects on Aβ degradation were evaluated on a cell-free system. An ELISA assay was applied to detect the level of Aβ1-40 and Aβ1-42. Western blots assay was employed to measure the levels of soluble amyloid precursor protein and insulin degrading enzyme (IDE. Three fractions of F. macrophylla modified Aβ accumulation by both inhibiting β-secretase and activating IDE. Three flavonoids modified Aβ accumulation by activating IDE. The activated IDE pool by the flavonoids was distinctly regulated by bacitracin (an IDE inhibitor. Furthermore, flavonoid 94-18-13 also modulates Aβ accumulation by enhancing IDE expression. In conclusion, the components of F. macrophylla possess the potential for developing new therapeutic drugs for Alzheimer's disease.

  15. Structural properties of Gerstmann-Straussler-Scheinker disease amyloid protein.

    Science.gov (United States)

    Salmona, Mario; Morbin, Michela; Massignan, Tania; Colombo, Laura; Mazzoleni, Giulia; Capobianco, Raffaella; Diomede, Luisa; Thaler, Florian; Mollica, Luca; Musco, Giovanna; Kourie, Joseph J; Bugiani, Orso; Sharma, Deepak; Inouye, Hideyo; Kirschner, Daniel A; Forloni, Gianluigi; Tagliavini, Fabrizio

    2003-11-28

    Prion protein (PrP) amyloid formation is a central feature of genetic and acquired forms of prion disease such as Gerstmann-Sträussler-Scheinker disease (GSS) and variant Creutzfeldt-Jakob disease. The major component of GSS amyloid is a PrP fragment spanning residues approximately 82-146. To investigate the determinants of the physicochemical properties of this fragment, we synthesized PrP-(82-146) and variants thereof, including entirely and partially scrambled peptides. PrP-(82-146) readily formed aggregates that were partially resistant to protease digestion. Peptide assemblies consisted of 9.8-nm-diameter fibrils having a parallel cross-beta-structure. Second derivative of infrared spectra indicated that PrP-(82-146) aggregates are primarily composed of beta-sheet (54%) and turn (24%) which is consistent with their amyloid-like properties. The peptide induced a remarkable increase in plasma membrane microviscosity of primary neurons. Modification of the amino acid sequence 106-126 caused a striking increase in aggregation rate, with formation of large amount of protease-resistant amorphous material and relatively few amyloid fibrils. Alteration of the 127-146 region had even more profound effects, with the inability to generate amyloid fibrils. These data indicate that the intrinsic properties of PrP-(82-146) are dependent upon the integrity of the C-terminal region and account for the massive deposition of PrP amyloid in GSS.

  16. Prediction of Peptide and Protein Propensity for Amyloid Formation.

    Directory of Open Access Journals (Sweden)

    Carlos Família

    Full Text Available Understanding which peptides and proteins have the potential to undergo amyloid formation and what driving forces are responsible for amyloid-like fiber formation and stabilization remains limited. This is mainly because proteins that can undergo structural changes, which lead to amyloid formation, are quite diverse and share no obvious sequence or structural homology, despite the structural similarity found in the fibrils. To address these issues, a novel approach based on recursive feature selection and feed-forward neural networks was undertaken to identify key features highly correlated with the self-assembly problem. This approach allowed the identification of seven physicochemical and biochemical properties of the amino acids highly associated with the self-assembly of peptides and proteins into amyloid-like fibrils (normalized frequency of β-sheet, normalized frequency of β-sheet from LG, weights for β-sheet at the window position of 1, isoelectric point, atom-based hydrophobic moment, helix termination parameter at position j+1 and ΔG° values for peptides extrapolated in 0 M urea. Moreover, these features enabled the development of a new predictor (available at http://cran.r-project.org/web/packages/appnn/index.html capable of accurately and reliably predicting the amyloidogenic propensity from the polypeptide sequence alone with a prediction accuracy of 84.9 % against an external validation dataset of sequences with experimental in vitro, evidence of amyloid formation.

  17. Eugenol prevents amyloid formation of proteins and inhibits amyloid-induced hemolysis

    Science.gov (United States)

    Dubey, Kriti; Anand, Bibin G.; Shekhawat, Dolat Singh; Kar, Karunakar

    2017-02-01

    Eugenol has attracted considerable attention because of its potential for many pharmaceutical applications including anti-inflammatory, anti-tumorigenic and anti-oxidant properties. Here, we have investigated the effect of eugenol on amyloid formation of selected globular proteins. We find that both spontaneous and seed-induced aggregation processes of insulin and serum albumin (BSA) are significantly suppressed in the presence of eugenol. Isothermal titration calorimetric data predict a single binding site for eugenol-insulin complex confirming the affinity of eugenol for native soluble insulin species. We also find that eugenol suppresses amyloid-induced hemolysis. Our findings reveal the inherent ability of eugenol to stabilize native proteins and to delay the conversion of protein species of native conformation into β-sheet assembled mature fibrils, which seems to be crucial for its inhibitory effect.

  18. Tensile deformation and failure of amyloid and amyloid-like protein fibrils

    Science.gov (United States)

    Solar, Max; Buehler, Markus J.

    2014-03-01

    Here we report a series of full atomistic molecular dynamics simulations of six amyloid or amyloid-like protein fibrils in order to systematically understand the effect of different secondary structure motifs on the mechanical tensile and failure response of cross-\\beta protein fibrils. We find a similar failure behavior across the six structures; an initial failure event occurs at small strains involving cooperative rupture of a group of hydrogen bonds, followed by a slow one-by-one hydrogen bond rupture process as the remaining \\beta -sheets peel off with very low applied stress. We also find that the ultimate tensile strength of the protein fibrils investigated scales directly with the number of hydrogen bonds per unit area which break in the initial rupture event. Our results provide insights into structure-property relationships in protein fibrils important for disease and engineering applications and lay the groundwork for the development of materials selection criteria for the design of de novo amyloid-based functional biomaterials.

  19. Rabbit serum amyloid protein A: expression and primary structure deduced from cDNA sequences.

    Science.gov (United States)

    Rygg, M; Marhaug, G; Husby, G; Dowton, S B

    1991-12-01

    Serum amyloid A protein (SAA), the precursor of amyloid protein A (AA) in deposits of secondary amyloidosis, is an acute phase plasma apolipoprotein produced by hepatocytes. The primary structure of SAA demonstrates high interspecies homology. Several isoforms exist in individual species, probably with different amyloidogenic potential. The nucleotide sequences of two different rabbit serum amyloid A cDNA clones have been analysed, one (corresponding to SAA1) 569 base pairs (bp) long and the other (corresponding to SAA2) 513 bp long. Their deduced amino acid sequences differ at five amino acid positions, four of which are located in the NH2-terminal region of the protein. The deduced amino acid sequence of SAA2 corresponds to rabbit protein AA previously described except for one amino acid in position 22. Eighteen hours after turpentine stimulation, rabbit SAA mRNA is abundant in liver, while lower levels are present in spleen. None of the other extrahepatic organs studied showed any SAA mRNA expression. A third mRNA species (1.9 kb) hybridizing with a single-stranded RNA probe transcribed from the rabbit SAA cDNA, was identified. SAA1 and SAA2 mRNA were found in approximately equal amounts in turpentine-stimulated rabbit liver, but seem to be coordinately decreased after repeated inflammatory stimulation.

  20. Interaction of amyloid inhibitor proteins with amyloid beta peptides: insight from molecular dynamics simulations.

    Directory of Open Access Journals (Sweden)

    Payel Das

    Full Text Available Knowledge of the detailed mechanism by which proteins such as human αB- crystallin and human lysozyme inhibit amyloid beta (Aβ peptide aggregation is crucial for designing treatment for Alzheimer's disease. Thus, unconstrained, atomistic molecular dynamics simulations in explicit solvent have been performed to characterize the Aβ17-42 assembly in presence of the αB-crystallin core domain and of lysozyme. Simulations reveal that both inhibitor proteins compete with inter-peptide interaction by binding to the peptides during the early stage of aggregation, which is consistent with their inhibitory action reported in experiments. However, the Aβ binding dynamics appear different for each inhibitor. The binding between crystallin and the peptide monomer, dominated by electrostatics, is relatively weak and transient due to the heterogeneous amino acid distribution of the inhibitor surface. The crystallin-bound Aβ oligomers are relatively long-lived, as they form more extensive contact surface with the inhibitor protein. In contrast, a high local density of arginines from lysozyme allows strong binding with Aβ peptide monomers, resulting in stable complexes. Our findings not only illustrate, in atomic detail, how the amyloid inhibitory mechanism of human αB-crystallin, a natural chaperone, is different from that of human lysozyme, but also may aid de novo design of amyloid inhibitors.

  1. Nucleation Process of a Fibril Precursor in the C-Terminal Segment of Amyloid

    Science.gov (United States)

    Baftizadeh, Fahimeh; Pietrucci, Fabio; Biarnés, Xevi; Laio, Alessandro

    2013-04-01

    By extended atomistic simulations in explicit solvent and bias-exchange metadynamics, we study the aggregation process of 18 chains of the C-terminal segment of amyloid-β, an intrinsically disordered protein involved in Alzheimer’s disease and prone to form fibrils. Starting from a disordered aggregate, we are able to observe the formation of an ordered nucleus rich in beta sheets. The rate limiting step in the nucleation pathway involves crossing a barrier of approximately 40kcal/mol and is associated with the formation of a very specific interdigitation of the side chains belonging to different sheets. This structural pattern is different from the one observed experimentally in a microcrystal of the same system, indicating that the structure of a “nascent” fibril may differ from the one of an “extended” fibril.

  2. The formation of bioactive amyloid species by prion proteins in vitro and in cells.

    Science.gov (United States)

    Liu, Yuanbin; Ritter, Christiane; Riek, Roland; Schubert, David

    2006-10-09

    Amyloid proteins are a group of proteins that can polymerize into cross beta-sheeted amyloid species. We have found that enhancing cellular 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) formazan exocytosis is a common property of bioactive amyloid species formed from all of the amyloid proteins tested to date. In this report, we show that the infectious amyloid species of the prion protein HET-s of the filamentous fungus Podospora anserina, like other amyloidogenic proteins, also enhances MTT formazan exocytosis. More strikingly, cellular MTT formazan exocytosis revealed the formation of bioactive amyloid species in prion-infected mouse N2a neuroblastoma cells. These findings suggest that cellular MTT formazan exocytosis can be useful for studying the roles of bioactive amyloid species in prion infectivity and prion-induced neurodegeneration.

  3. Salt anions promote the conversion of HypF-N into amyloid-like oligomers and modulate the structure of the oligomers and the monomeric precursor state.

    Science.gov (United States)

    Campioni, Silvia; Mannini, Benedetta; López-Alonso, Jorge P; Shalova, Irina N; Penco, Amanda; Mulvihill, Estefania; Laurents, Douglas V; Relini, Annalisa; Chiti, Fabrizio

    2012-12-07

    An understanding of the solution factors contributing to the rate of aggregation of a protein into amyloid oligomers, to the modulation of the conformational state populated prior to aggregation and to the structure/morphology of the resulting oligomers is one of the goals of present research in this field. We have studied the influence of six different salts on the conversion of the N-terminal domain of Escherichiacoli HypF (HypF-N) into amyloid-like oligomers under conditions of acidic pH. Our results show that salts having different anions (NaCl, NaClO(4), NaI, Na(2)SO(4)) accelerate oligomerization with an efficacy that follows the electroselectivity series of the anions (SO(4)(2-)≥ ClO(4)(-)>I(-)>Cl(-)). By contrast, salts with different cations (NaCl, LiCl, KCl) have similar effects. We also investigated the effect of salts on the structure of the final and initial states of HypF-N aggregation. The electroselectivity series does not apply to the effect of anions on the structure of the oligomers. By contrast, it applies to their effect on the content of secondary structure and on the exposure of hydrophobic clusters of the monomeric precursor state. The results therefore indicate that the binding of anions to the positively charged residues of HypF-N at low pH is the mechanism by which salts modulate the rate of oligomerization and the structure of the monomeric precursor state but not the structure of the resulting oligomers. Overall, the data contribute to rationalize the effect of salts on amyloid-like oligomer formation and to explain the role of charged biological macromolecules in protein aggregation processes.

  4. The proteome response to amyloid protein expression in vivo.

    Directory of Open Access Journals (Sweden)

    Ricardo A Gomes

    Full Text Available Protein misfolding disorders such as Alzheimer, Parkinson and transthyretin amyloidosis are characterized by the formation of protein amyloid deposits. Although the nature and location of the aggregated proteins varies between different diseases, they all share similar molecular pathways of protein unfolding, aggregation and amyloid deposition. Most effects of these proteins are likely to occur at the proteome level, a virtually unexplored reality. To investigate the effects of an amyloid protein expression on the cellular proteome, we created a yeast expression system using human transthyretin (TTR as a model amyloidogenic protein. We used Saccharomyces cerevisiae, a living test tube, to express native TTR (non-amyloidogenic and the amyloidogenic TTR variant L55P, the later forming aggregates when expressed in yeast. Differential proteome changes were quantitatively analyzed by 2D-differential in gel electrophoresis (2D-DIGE. We show that the expression of the amyloidogenic TTR-L55P causes a metabolic shift towards energy production, increased superoxide dismutase expression as well as of several molecular chaperones involved in protein refolding. Among these chaperones, members of the HSP70 family and the peptidyl-prolyl-cis-trans isomerase (PPIase were identified. The latter is highly relevant considering that it was previously found to be a TTR interacting partner in the plasma of ATTR patients but not in healthy or asymptomatic subjects. The small ubiquitin-like modifier (SUMO expression is also increased. Our findings suggest that refolding and degradation pathways are activated, causing an increased demand of energetic resources, thus the metabolic shift. Additionally, oxidative stress appears to be a consequence of the amyloidogenic process, posing an enhanced threat to cell survival.

  5. Amyloid-clearing proteins and their epigenetic regulation as a therapeutic target in Alzheimer’s disease

    Directory of Open Access Journals (Sweden)

    Natalia N Nalivaeva

    2014-09-01

    Full Text Available Abnormal elevation of amyloid β-peptide (Aβ levels in the brain is the primary trigger for neuronal cell death specific to Alzheimer’s disease (AD. It is now evident that Aβ levels in the brain are manipulable due to a dynamic equilibrium between its production from the amyloid precursor protein (APP and removal by amyloid clearance proteins. Clearance can be either enzymic or non-enzymic (binding/transport proteins. Intriguingly several of the main amyloid-degrading enzymes (ADEs are members of the M13 peptidase family (neprilysin (NEP, NEP2 and the endothelin converting enzymes (ECE-1 and -2. A distinct metallopeptidase, insulin-degrading enzyme (IDE, also contributes to Aβ degradation in the brain. The ADE family currently embraces more than 20 members, both membrane-bound and soluble, and of differing cellular locations. NEP plays an important role in brain function terminating neuropeptide signals. Its decrease in specific brain areas with age or after hypoxia, ischaemia or stroke contribute significantly to the development of AD pathology. The recently discovered mechanism of epigenetic regulation of NEP (and other genes by the APP intracellular domain (AICD and its dependence on the cell type and APP isoform expression suggest possibilities for selective manipulation of NEP gene expression in neuronal cells. We have also observed that another amyloid-clearing protein, namely transthyretin (TTR, is also regulated in the neuronal cell by a mechanism similar to NEP. Dependence of amyloid clearance proteins on histone deacetylases and the ability of HDAC inhibitors to up-regulate their expression in the brain opens new avenues for developing preventive strategies in AD.

  6. Neurotrophic and Neurotoxic Effects of Amyloid |beta Protein: Reversal by Tachykinin Neuropeptides

    Science.gov (United States)

    Yankner, Bruce A.; Duffy, Lawrence K.; Kirschner, Daniel A.

    1990-10-01

    The amyloid β protein is deposited in the brains of patients with Alzheimer's disease but its pathogenic role is unknown. In culture, the amyloid β protein was neurotrophic to undifferentiated hippocampal neurons at low concentrations and neurotoxic to mature neurons at higher concentrations. In differentiated neurons, amyloid β protein caused dendritic and axonal retraction followed by neuronal death. A portion of the amyloid β protein (amino acids 25 to 35) mediated both the trophic and toxic effects and was homologous to the tachykinin neuropeptide family. The effects of the amyloid β protein were mimicked by tachykinin antagonists and completely reversed by specific tachykinin agonists. Thus, the amyloid β protein could function as a neurotrophic factor for differentiating neurons, but at high concentrations in mature neurons, as in Alzheimer's disease, could cause neuronal degeneration.

  7. Cholesterol-induced astrocyte activation is associated with increased amyloid precursor protein expression and processing%胆固醇介导的星形胶质细胞活化与淀粉样前体蛋白表达升高和进展相关

    Institute of Scientific and Technical Information of China (English)

    Evangelina Avila-Muñoz; Clorinda Arias

    2015-01-01

    Cholesterol is essential for maintaining lipid raft integrity and has been regarded as a crucial regulatory factor for amyloidogenesis in Alzheimer's disease (AD). The vast majority of studies on amyloid precursor protein (APP) metabolism and amyloid β-protein (Aβ) production have focused on neurons. The role of astrocytes re-mains largely unexplored, despite the presence of activated astrocytes in the brains of most patients with AD and in transgenic models of the disease. The role of cholesterol in Aβ production has been thoroughly studied in neu-rons and attributed to the participation of lipid rafts in APP metabolism. Thus, in this study, we analyzed the effect of cholesterol loading in astrocytes and analyzed the expression and processing of APP. We found that cholesterol exposure induced astrocyte activation, increased APP content, and enhanced the interaction of APP with BACE-1. These effects were associated with an enrichment of ganglioside GM1-cholesterol patches in the astro-cyte membrane and with increased ROS production.%胆固醇对于保持脂筏的完整性起必要作用,其被认为是阿尔茨海默病(AD)中淀粉样蛋白生成的关键调节因子。大多数关于淀粉样前体蛋白(APP)代谢和β淀粉样蛋白(Aβ)生成的研究都聚焦于神经元。虽然在大多数 AD 患者和 AD 转基因模型脑内发现活化的星形胶质细胞,但星形胶质细胞在 AD 中的作用尚未得到充分探索。在神经元 Aβ生成中胆固醇的作用已得到充分研究,并归因于 APP 代谢中脂筏的参与。因此,本研究分析星形胶质细胞中胆固醇的作用,以及 APP 的表达和进展。本研究发现,胆固醇的表达导致星形胶质细胞活化,提高 APP 水平,增强 APP 和 BACE-1的交互作用。这些作用与星形胶质细胞细胞膜的神经节苷脂 GM1-胆固醇斑块和增高的 ROS 相关。

  8. Observation of amyloid precursor protein cleavage and Aβ generation in living cells by using multiphoton laser scanning microscopy%多光子激光扫描成像技术对活细胞内淀粉样前体蛋白裂解和β-淀粉样蛋白生成的观察

    Institute of Scientific and Technical Information of China (English)

    李晓晴; 张苏明; 杨华静; 张智红

    2007-01-01

    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 pcDNAS.O 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 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 p cleavage and y cleavage of APP.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.%目的 在活细胞内探究淀粉样前体蛋白(amyloid precursor protein,APP)的裂解和β-淀粉样蛋白(amyloid beta,Aβ)的生成机制.方法 利用PCR扩增CFP(编码蓝色荧光蛋白),YFP(编码黄色荧光蛋白)和C99(编码APP最后99个氨基酸)三片段.含有54

  9. Minocycline alleviates beta-amyloid protein and tau pathology via restraining neuroinflammation induced by diabetic metabolic disorder

    Directory of Open Access Journals (Sweden)

    Cai Z

    2013-08-01

    Full Text Available Zhiyou Cai,1 Yong Yan,2 Yonglong Wang2 1Department of Neurology, the Lu’an Affiliated Hospital of Anhui Medical University, Lu’an People’s Hospital, Lu’an, Anhui Province, People’s Republic of China; 2Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, People’s Republic of China Background: Compelling evidence has shown that diabetic metabolic disorder plays a critical role in the pathogenesis of Alzheimer’s disease, including increased expression of β-amyloid protein (Aβ and tau protein. Evidence has supported that minocycline, a tetracycline derivative, protects against neuroinflammation induced by neurodegenerative disorders or cerebral ischemia. This study has evaluated minocycline influence on expression of Aβ protein, tau phosphorylation, and inflammatory cytokines (interleukin-1β and tumor necrosis factor-α in the brain of diabetic rats to clarify neuroprotection by minocycline under diabetic metabolic disorder. Method: An animal model of diabetes was established by high fat diet and intraperitoneal injection of streptozocin. In this study, we investigated the effect of minocycline on expression of Aβ protein, tau phosphorylation, and inflammatory cytokines (interleukin-1β and tumor necrosis factor-α in the hippocampus of diabetic rats via immunohistochemistry, western blotting, and enzyme-linked immunosorbent assay. Results: These results showed that minocycline decreased expression of Aβ protein and lowered the phosphorylation of tau protein, and retarded the proinflammatory cytokines, but not amyloid precursor protein. Conclusion: On the basis of the finding that minocycline had no influence on amyloid precursor protein and beta-site amyloid precursor protein cleaving enzyme 1 which determines the speed of Aβ generation, the decreases in Aβ production and tau hyperphosphorylation by minocycline are through inhibiting

  10. Non-targeted identification of prions and amyloid-forming proteins from yeast and mammalian cells.

    Science.gov (United States)

    Kryndushkin, Dmitry; Pripuzova, Natalia; Burnett, Barrington G; Shewmaker, Frank

    2013-09-20

    The formation of amyloid aggregates is implicated both as a primary cause of cellular degeneration in multiple human diseases and as a functional mechanism for providing extraordinary strength to large protein assemblies. The recent identification and characterization of several amyloid proteins from diverse organisms argues that the amyloid phenomenon is widespread in nature. Yet identifying new amyloid-forming proteins usually requires a priori knowledge of specific candidates. Amyloid fibers can resist heat, pressure, proteolysis, and denaturation by reagents such as urea or sodium dodecyl sulfate. Here we show that these properties can be exploited to identify naturally occurring amyloid-forming proteins directly from cell lysates. This proteomic-based approach utilizes a novel purification of amyloid aggregates followed by identification by mass spectrometry without the requirement for special genetic tools. We have validated this technique by blind identification of three amyloid-based yeast prions from laboratory and wild strains and disease-related polyglutamine proteins expressed in both yeast and mammalian cells. Furthermore, we found that polyglutamine aggregates specifically recruit some stress granule components, revealing a possible mechanism of toxicity. Therefore, core amyloid-forming proteins as well as strongly associated proteins can be identified directly from cells of diverse origin.

  11. Amyloid protein unfolding and insertion kinetics on neuronal membrane mimics

    Science.gov (United States)

    Qiu, Liming; Buie, Creighton; Vaughn, Mark; Cheng, Kwan

    2010-03-01

    Atomistic details of beta-amyloid (Aβ ) protein unfolding and lipid interaction kinetics mediated by the neuronal membrane surface are important for developing new therapeutic strategies to prevent and cure Alzheimer's disease. Using all-atom MD simulations, we explored the early unfolding and insertion kinetics of 40 and 42 residue long Aβ in binary lipid mixtures with and without cholesterol that mimic the cholesterol-depleted and cholesterol-enriched lipid nanodomains of neurons. The protein conformational transition kinetics was evaluated from the secondary structure profile versus simulation time plot. The extent of membrane disruption was examined by the calculated order parameters of lipid acyl chains and cholesterol fused rings as well as the density profiles of water and lipid headgroups at defined regions across the lipid bilayer from our simulations. Our results revealed that both the cholesterol content and the length of the protein affect the protein-insertion and membrane stability in our model lipid bilayer systems.

  12. Modeling the Aggregation Propensity and Toxicity of Amyloid-β Variants

    DEFF Research Database (Denmark)

    Tiwari, Manish Kumar; Kepp, Kasper Planeta

    2015-01-01

    Protein aggregation is a hallmark of many neurodegenerative disorders. Alzheimer’s disease (AD) is directly linked to deposits of amyloid-β (Aβ) derived from the amyloidprotein precursor (AβPP), and multiple experimental studies have investigated the aggregation behavior of these amyloids...

  13. Native human serum amyloid P component is a single pentamer

    DEFF Research Database (Denmark)

    Sørensen, Inge Juul; Andersen, Ove; Nielsen, EH;

    1995-01-01

    Serum amyloid P component (SAP) and C-reactive protein (CRP) are members of the pentraxin protein family. SAP is the precursor protein to amyloid P component present in all forms of amyloidosis. The prevailing notion is that SAP in circulation has the form of a double pentameric molecule (decamer...

  14. Effect of Metal Chelators on γ-Secretase Indicates That Calcium and Magnesium Ions Facilitate Cleavage of Alzheimer Amyloid Precursor Substrate

    Directory of Open Access Journals (Sweden)

    Michael Ho

    2011-01-01

    Full Text Available Gamma-secretase is involved in the production of Aβ amyloid peptides. It cleaves the transmembrane domain of the amyloid precursor protein (APP at alternative sites to produce Aβ and the APP intracellular domain (AICD. Metal ions play an important role in Aβ aggregation and metabolism, thus metal chelators and ligands represent potential therapeutic agents for AD treatment. A direct effect of metal chelators on γ-secretase has not yet been investigated. The authors used an in vitro  γ-secretase assay consisting of cleavage of APP C100-3XFLAG by endogenous γ-secretase from rodent brains and human neuroblastoma SH-SY5Y, and detected AICD production by western blotting. Adding metalloprotease inhibitors to the reaction showed that clioquinol, phosphoramidon, and zinc metalloprotease inhibitors had no significant effect on γ-secretase activity. In contrast, phenanthroline, EDTA, and EGTA markedly decreased γ-secretase activity that could be restored by adding back calcium and magnesium ions. Mg2+ stabilized a 1,000 kDa presenilin 1 complex through blue native gel electrophoresis and size-exclusion chromatography. Data suggest that Ca2+ and Mg2+ stabilize γ-secretase and enhance its activity.

  15. The coarse-grained OPEP force field for non-amyloid and amyloid proteins.

    Science.gov (United States)

    Chebaro, Yassmine; Pasquali, Samuela; Derreumaux, Philippe

    2012-08-02

    Coarse-grained protein models with various levels of granularity and degrees of freedom offer the possibility to explore many phenomena including folding, assembly, and recognition in terms of dynamics and thermodynamics that are inaccessible to all-atom representations in explicit aqueous solution. Here, we present a refined version of the coarse-grained optimized potential for efficient protein structure prediction (OPEP) based on a six-bead representation. The OPEP version 4.0 parameter set, which uses a new analytical formulation for the nonbonded interactions and adds specific side-chain-side-chain interactions for α-helix, is subjected to three tests. First, we show that molecular dynamics simulations at 300 K preserve the experimental rigid conformations of 17 proteins with 37-152 amino acids within a root-mean-square deviation (RMSD) of 3.1 Å after 30 ns. Extending the simulation time to 100 ns for five proteins does not change the RMSDs. Second, replica exchange molecular dynamics (REMD) simulations recover the NMR structures of three prototypical β-hairpin and α-helix peptides and the NMR three-stranded β-sheet topology of a 37-residue WW domain, starting from randomly chosen states. Third, REMD simulations on the ccβ peptide show a temperature transition from a three-stranded coiled coil to amyloid-like aggregates consistent with experiments, while simulations on low molecular weight aggregates of the prion protein helix 1 do not. Overall, these studies indicate the effectiveness of our OPEP4 coarse-grained model for protein folding and aggregation, and report two future directions for improvement.

  16. Immunohistochemical identification and crossreactions of amyloid-A fibril protein in man and eleven other species

    OpenAIRE

    Gruys, E.; Linke, R.P.; Hol, P.R.; Geisel, O.; Nathrath, W.B.J.; Trautwein, G

    1984-01-01

    Antisera were prepared in rabbits, sheep or chicken against purified amyloid fibril protein AA from man, mouse, stone marten, dog, cow and hamster. These antisera were tested by immunodiffusion against all purified antigens and applied to tissue sections containing amyloid from man, mouse, hamster, guinea pig, rabbit, cat, dog, mink, stone marten, pine marten, cow and horse. The binding of the antibodies to amyloid in tissue sections was assessed by the indirect immunoperoxidase method. The s...

  17. Oxidative stress up-regulates the expression of β-Amyloid precursor protein cleavage enzyme 1 in SH-SY5Y human neuroblastoma cells%氧化应激上调人神经母细胞瘤细胞内β-裂解酶的表达

    Institute of Scientific and Technical Information of China (English)

    谷心灵; 孟斐; 李良

    2012-01-01

    Objective To investigate the role of oxidative stress in the expression of p-Amyloid precursor protein cleavage enzyme 1 ( BACE1) and the changes DNA methylation and histone acetylation. Methods Cultured SH-SY5Y cells treated with H2O2 were used to test the expressions of BACE1, DNA methyltransferases 1, 3A (DN-MT1,DNMT3A) and histone deacetyltranferase (HDAC) by were examined by Western blot. The level of mRNA of BACE1 was assessed by RT-PCR. Acetylation level of histone H3 and H4 was examined by optical density assay. Results Both BACE1 mRNA and protein levels were up-regulated significantly after H2O2 treatment for 1 and 72 h; DNMT1 and DNMT3A expressions were decreased to 75% and 65% of control respectively after H2O2 treatment for 72 h; HD AC3 level was increased by 1.6 folds as compared with control; While the level of histone H3 acetylation was decreased and there was no change with histone H4 acetylation. Conclusions Oxidative stress may regulate BACE1 expression in SH-SY5 Y through alteration of DNA methylation and histone acetylation which play a role in Alzheimer's disease (AD) pathogenesis.%目的 研究氧化应激对人神经母细胞瘤细胞(SH-SY5Y)β-裂解酶(BACE1)表达的影响及组蛋白乙酰化、DNA甲基化的改变.方法 采用H2O2处理体外培养的SH-SY5Y,Westem blot法检测细胞的BACE1表达及DNA甲基转移酶(DNMTs)和组蛋白去乙酰化酶(HDAC)的表达;实时定量PCR检测BACE1 mRNA的表达;吸光度值法检测组蛋白3(H3)和组蛋白4(H4)整体乙酰化水平.结果 SH-SY5Y细胞经H2O2处理1和72 h后BACE1 mRNA和蛋白表达均明显增多;H2O2处理72 h后DNMT1、DNMT3A表达均下降,分别是对照组的75%和65%(P<0.01);而组蛋白去乙酰化酶HDAC3的表达增高至对照组的1.6倍(P<0.01);同时,组蛋白H3整体乙酰化水平下降,但H4乙酰化水平无明显改变.结论 氧化应激可能通过改变SH-SY5Y细胞内DNA甲基化水平及组蛋白乙酰化状态调节BACE1的

  18. Positive evolutionary selection of an HD motif on Alzheimer precursor protein orthologues suggests a functional role.

    Directory of Open Access Journals (Sweden)

    István Miklós

    2012-02-01

    Full Text Available HD amino acid duplex has been found in the active center of many different enzymes. The dyad plays remarkably different roles in their catalytic processes that usually involve metal coordination. An HD motif is positioned directly on the amyloid beta fragment (Aβ and on the carboxy-terminal region of the extracellular domain (CAED of the human amyloid precursor protein (APP and a taxonomically well defined group of APP orthologues (APPOs. In human Aβ HD is part of a presumed, RGD-like integrin-binding motif RHD; however, neither RHD nor RXD demonstrates reasonable conservation in APPOs. The sequences of CAEDs and the position of the HD are not particularly conserved either, yet we show with a novel statistical method using evolutionary modeling that the presence of HD on CAEDs cannot be the result of neutral evolutionary forces (p<0.0001. The motif is positively selected along the evolutionary process in the majority of APPOs, despite the fact that HD motif is underrepresented in the proteomes of all species of the animal kingdom. Position migration can be explained by high probability occurrence of multiple copies of HD on intermediate sequences, from which only one is kept by selective evolutionary forces, in a similar way as in the case of the "transcription binding site turnover." CAED of all APP orthologues and homologues are predicted to bind metal ions including Amyloid-like protein 1 (APLP1 and Amyloid-like protein 2 (APLP2. Our results suggest that HDs on the CAEDs are most probably key components of metal-binding domains, which facilitate and/or regulate inter- or intra-molecular interactions in a metal ion-dependent or metal ion concentration-dependent manner. The involvement of naturally occurring mutations of HD (Tottori (D7N and English (H6R mutations in early onset Alzheimer's disease gives additional support to our finding that HD has an evolutionary preserved function on APPOs.

  19. Small heat shock proteins potentiate amyloid dissolution by protein disaggregases from yeast and humans.

    Directory of Open Access Journals (Sweden)

    Martin L Duennwald

    Full Text Available How small heat shock proteins (sHsps might empower proteostasis networks to control beneficial prions or disassemble pathological amyloid is unknown. Here, we establish that yeast sHsps, Hsp26 and Hsp42, inhibit prionogenesis by the [PSI+] prion protein, Sup35, via distinct and synergistic mechanisms. Hsp42 prevents conformational rearrangements within molten oligomers that enable de novo prionogenesis and collaborates with Hsp70 to attenuate self-templating. By contrast, Hsp26 inhibits self-templating upon binding assembled prions. sHsp binding destabilizes Sup35 prions and promotes their disaggregation by Hsp104, Hsp70, and Hsp40. In yeast, Hsp26 or Hsp42 overexpression prevents [PSI+] induction, cures [PSI+], and potentiates [PSI+]-curing by Hsp104 overexpression. In vitro, sHsps enhance Hsp104-catalyzed disaggregation of pathological amyloid forms of α-synuclein and polyglutamine. Unexpectedly, in the absence of Hsp104, sHsps promote an unprecedented, gradual depolymerization of Sup35 prions by Hsp110, Hsp70, and Hsp40. This unanticipated amyloid-depolymerase activity is conserved from yeast to humans, which lack Hsp104 orthologues. A human sHsp, HspB5, stimulates depolymerization of α-synuclein amyloid by human Hsp110, Hsp70, and Hsp40. Thus, we elucidate a heretofore-unrecognized human amyloid-depolymerase system that could have applications in various neurodegenerative disorders.

  20. Functional Amyloid Formation within Mammalian Tissue.

    Directory of Open Access Journals (Sweden)

    2005-11-01

    Full Text Available Amyloid is a generally insoluble, fibrous cross-beta sheet protein aggregate. The process of amyloidogenesis is associated with a variety of neurodegenerative diseases including Alzheimer, Parkinson, and Huntington disease. We report the discovery of an unprecedented functional mammalian amyloid structure generated by the protein Pmel17. This discovery demonstrates that amyloid is a fundamental nonpathological protein fold utilized by organisms from bacteria to humans. We have found that Pmel17 amyloid templates and accelerates the covalent polymerization of reactive small molecules into melanin-a critically important biopolymer that protects against a broad range of cytotoxic insults including UV and oxidative damage. Pmel17 amyloid also appears to play a role in mitigating the toxicity associated with melanin formation by sequestering and minimizing diffusion of highly reactive, toxic melanin precursors out of the melanosome. Intracellular Pmel17 amyloidogenesis is carefully orchestrated by the secretory pathway, utilizing membrane sequestration and proteolytic steps to protect the cell from amyloid and amyloidogenic intermediates that can be toxic. While functional and pathological amyloid share similar structural features, critical differences in packaging and kinetics of assembly enable the usage of Pmel17 amyloid for normal function. The discovery of native Pmel17 amyloid in mammals provides key insight into the molecular basis of both melanin formation and amyloid pathology, and demonstrates that native amyloid (amyloidin may be an ancient, evolutionarily conserved protein quaternary structure underpinning diverse pathways contributing to normal cell and tissue physiology.

  1. Functional amyloid formation within mammalian tissue.

    Directory of Open Access Journals (Sweden)

    Douglas M Fowler

    2006-01-01

    Full Text Available Amyloid is a generally insoluble, fibrous cross-beta sheet protein aggregate. The process of amyloidogenesis is associated with a variety of neurodegenerative diseases including Alzheimer, Parkinson, and Huntington disease. We report the discovery of an unprecedented functional mammalian amyloid structure generated by the protein Pmel17. This discovery demonstrates that amyloid is a fundamental nonpathological protein fold utilized by organisms from bacteria to humans. We have found that Pmel17 amyloid templates and accelerates the covalent polymerization of reactive small molecules into melanin-a critically important biopolymer that protects against a broad range of cytotoxic insults including UV and oxidative damage. Pmel17 amyloid also appears to play a role in mitigating the toxicity associated with melanin formation by sequestering and minimizing diffusion of highly reactive, toxic melanin precursors out of the melanosome. Intracellular Pmel17 amyloidogenesis is carefully orchestrated by the secretory pathway, utilizing membrane sequestration and proteolytic steps to protect the cell from amyloid and amyloidogenic intermediates that can be toxic. While functional and pathological amyloid share similar structural features, critical differences in packaging and kinetics of assembly enable the usage of Pmel17 amyloid for normal function. The discovery of native Pmel17 amyloid in mammals provides key insight into the molecular basis of both melanin formation and amyloid pathology, and demonstrates that native amyloid (amyloidin may be an ancient, evolutionarily conserved protein quaternary structure underpinning diverse pathways contributing to normal cell and tissue physiology.

  2. 同型半胱氨酸对大鼠学习记忆及海马APP代谢影响%Influence of hyperhomocysteinemia on learning and memory ability and expression of β-amyloid precursor protein of hippocampus and intervention effect of folic acid in rats

    Institute of Scientific and Technical Information of China (English)

    王健; 张永泽; 康美玉; 潘丽兰; 史玉; 高玉梅; 李凤铭

    2012-01-01

    Objective To explore the influence of hyperhotnocysteinemia( HHcy) on learning and memory ability and expression of β-amyloid precursor protein of hippocampus and the intervention effect of folic acid (FA) in rats. Methods Forty Wislar rats were randomly divided into normal control group, HHcy group, and two FA intervention groups(low and high dose) . Methionine( 1 g/kg·d) was dissolved in drinking water to make HHcy model. Treatment with FA(0.7 and 3.4 mg/kg·d) via intragastric intubation was administered in FA groups for 8 weeks. Plasma concentrations of homocysteinemia(Hcy) and FA before and after the experiment were measured. The rats' learning and memory abilities were tested by Morris water maze test. At the end of 8 weeks experiment, immunohistochemistry was used to observe the expression of p-amyloid precusor protein ( APP) in hippocampus. Results Compared with the normal control and FA groups,the escape latency in HHcy group was significantly longer;the numbers of passing the platform region was significantly less;the staying time in the platform region was significantly shorter( P <0.05 -0.01) ; and the mean values of APP and its metabolic secretase in region of hippocampus was significantly higher( P < 0. 01 ) . The results of all tests were not significantly different between the normal control group and FA groups. Conclusion HHcy can induce learning and memory impairment and decreased the expression of APP in hippocampus in rats. FA supplementation could attenuate the adverse effects.%目的 探讨高同型半胱氨酸血症(HHcy)对大鼠学习记忆能力和海马β-淀粉样前体蛋白(APP)代谢影响及叶酸干预作用.方法 将40只Wistar大鼠随机分为对照组、HHcy组和叶酸干预组,每组10只,在大鼠饮水中添加蛋氨酸(1.0g/kg)制作HHcy模型,叶酸低、高剂量干预组大鼠同时分别给予叶酸0.7和3.4mg/kg灌胃,持续8周.在实验前后测定各组血浆同型半胱氨酸(Hcy)、叶酸浓度,采用Morris水

  3. Immunohistochemical identification and crossreactions of amyloid-A fibril protein in man and eleven other species

    NARCIS (Netherlands)

    Gruys, E.; Linke, R.P.; Hol, P.R.; Geisel, O.; Nathrath, W.B.J.; Trautwein, G.

    1984-01-01

    Antisera were prepared in rabbits, sheep or chicken against purified amyloid fibril protein AA from man, mouse, stone marten, dog, cow and hamster. These antisera were tested by immunodiffusion against all purified antigens and applied to tissue sections containing amyloid from man, mouse, hamster,

  4. Islet amyloid polypeptide forms rigid lipid-protein amyloid fibrils on supported phospholipid bilayers.

    Science.gov (United States)

    Domanov, Yegor A; Kinnunen, Paavo K J

    2008-02-08

    Islet amyloid polypeptide (IAPP) forms fibrillar amyloid deposits in the pancreatic islets of Langerhans of patients with type 2 diabetes mellitus, and its misfolding and aggregation are thought to contribute to beta-cell death. Increasing evidence suggests that IAPP fibrillization is strongly influenced by lipid membranes and, vice versa, that the membrane architecture and integrity are severely affected by amyloid growth. Here, we report direct fluorescence microscopic observations of the morphological transformations accompanying IAPP fibrillization on the surface of supported lipid membranes. Within minutes of application in submicromolar concentrations, IAPP caused extensive remodeling of the membrane including formation of defects, vesiculation, and tubulation. The effects of IAPP concentration, ionic strength, and the presence of amyloid seeds on the bilayer perturbation and peptide aggregation were examined. Growth of amyloid fibrils was visualized using fluorescently labeled IAPP or thioflavin T staining. Two-color imaging of the peptide and membranes revealed that the fibrils were initially composed of the peptide only, and vesiculation occurred in the points where growing fibers touched the lipid membrane. Interestingly, after 2-5 h of incubation, IAPP fibers became "wrapped" by lipid membranes derived from the supported membrane. Progressive increase in molecular-level association between amyloid and membranes in the maturing fibers was confirmed by Förster resonance energy transfer spectroscopy.

  5. Effects of Exogenous Hydrogen Sulfide on β-site Amyloid Precursor Protein Cleaving Enzyme 1 in Pheochromocytoma Cells%外源性硫化氢对嗜铬细胞瘤细胞β位淀粉样前体蛋白裂解酶1表达的影响

    Institute of Scientific and Technical Information of China (English)

    代政伟; 张华; 孟涛; 晏宁; 李洁颖; 晏勇

    2011-01-01

    Abstract Objective To observe the effects of exogenous hydrogen sulfide (H2S) on the expression of β-site amyloid precursor protein cleaving enzyme 1 (BACE1) and explore the possible ceDular signaling mechanism in pheochromocytoma (PC12) cells. Methods PC12 cells were exposed to different concentrations of sodium hydrosulfide (NaHS, the honor of H2S) for 24 hours. The levels of BACE1 mRNA and protein were detected by RT-PCR and Western blot,respectively. Western blot was also performed to detect the changes in the expressions of phosphorylated Akt-1 (pAkt1) and ERK1/2 (pERK1/2) proteins,which were key downstream proteins of PI3-K/Akt and MAPK/ ERK1/2 pathways,and BACE1 protein,which was affected by LY294002 and PD98059,the specific inhibitors of PD-K/Akt and MAPK/ ERK1/2 signaling pathways. The levels of AB42 in cellular culture medium was detected by ELBA. Results NaHS within the experimental concentration range decreased BACE1 expression in a dose-dependent manner, and the BACE1 expression reached the minimum level in PC12 cells exposed to 200 μmol/L NaHS. There were singificant differences in BACE1 expression between PC12 cells exposed to different concentrations of NaHS and control group (P 0.05). The expression of Aβ42 showed the same trend as BACE1 whether the inhibitors were used or not. Conclusion The PI3-K/Akt signaling pathway,not the MAPK/ERK1/2 signaling pathway, may be involved in the down-regulated expression of BACE1 induced by exogenous hydrogen sulfide in PC12 cells.%目的 观察外源性硫化氢(H2S)对嗜铬细胞瘤细胞(PC12)β位淀粉样前体蛋白裂解酶1( BACE1)表达的影响,并探讨可能涉及的细胞信号机制.方法用不同浓度的硫氢化钠(NaHS)处理体外培养的PC12细胞,利用RT-PCR和Western blot法检测细胞内BACE1 mRNA及蛋白表达;继以LY294002和PD98059分别阻断磷脂酰肌醇3-激酶/丝氨酸苏氨酸蛋白激酶(PI3-K/Akt)及丝裂酶原活化蛋白激酶/细胞外信号调节激酶1/2( MAPK

  6. Insulin-like growth factor-1 reduces β-amyloid precursor protein expression after ischemic white matter damage in near-term fetal sheep%胰岛素样生长因子-1减少胎羊缺血性脑白质损伤后淀粉样前体蛋白表达

    Institute of Scientific and Technical Information of China (English)

    曹云; Alistair Jan GUAN; Laura BENNET; David WU; Sherly GEORGE; Peter GLUCKMAN; 邵肖梅; Jian GUAN

    2004-01-01

    目的淀粉样前体蛋白(β-APP)是脑白质损伤早期敏感的指标,并参与缺氧缺血性脑损伤机制.本研究观察胎羊缺血性脑白质损伤及胰岛素样生长因子-1(IGF-1)治疗对淀粉样前体蛋白(β-APP)表达的影响.方法胎羊于胎龄117-124天(足月为147天)时通过双侧颈动脉阻塞30 min造成双侧脑缺血损伤,损伤后胎羊随机分为损伤组(n=8)和重组人IGF-1(rhIGF-1)治疗组(n=9);另设正常对照组(n=5),为假手术动物.治疗组缺血后90 min经侧脑室注射3μgrhIGF-1;损伤组经侧脑室注射等量人工脑脊液.缺血损伤后96 h结束实验,处死动物,取出胎羊,固定脑组织.免疫组化法检测脑白质胶质原纤维酸性蛋白(GFAP)、β-APP阳性细胞及白质内髓鞘碱性蛋白(MBP)密度.应用免疫荧光双标记观察APP表达阳性细胞.结果与正常对照组(27.8±4.8)比较,缺血损伤组MBP密度(4.7±7.1,P<0.001)明显减少.正常对照组未见β-APP阳性细胞,损伤后阳性细胞数明显增加(49.6±23.7,P<0.001),rhIGF-1治疗可减少β-APP阳性细胞数(17.9±16.5,P<0.01).免疫荧光双标记显示部分细胞为β-APP-GFAP双标阳性细胞.结论胎羊缺血性脑白质损伤可导致星形胶质细胞表达β-APP,β-APP表达增加可能与脑损伤有关.IGF-1可减少β-APP表达,可能是减轻脑白质损伤的机制之一.%Objective β-amyloid precursor protein (β-APP) is thought to be a sensitive marker for brain white matter damage (WMD) and participates in the mechanisms of hypoxic-ischemic brain damage. This paper aims to study the influence of ischemia and IGF-1 treatment on the expression of β-APP in white matter of near-term fetal sheep.Methods Romney-Suffolk fetal sheep were instrumented at 117 to 124 days of gestation (term= 147 days). Reversible cerebral ischemia was induced by occlusion of bilateral carotid arteries for 30 mins. After damage the sheep were randomly divided into two groups: the Ischemic group ( n =8) and

  7. Goodpasture Antigen-binding Protein/Ceramide Transporter Binds to Human Serum Amyloid P-Component and Is Present in Brain Amyloid Plaques

    NARCIS (Netherlands)

    Mencarelli, Chiara; Bode, Gerard H.; Losen, Mario; Kulharia, Mahesh; Molenaar, Peter C.; Veerhuis, Robert; Steinbusch, Harry W. M.; De Baets, Marc H.; Nicolaes, Gerry A. F.; Martinez-Martinez, Pilar

    2012-01-01

    Serum amyloid P component (SAP) is a non-fibrillar glycoprotein belonging to the pentraxin family of the innate immune system. SAP is present in plasma, basement membranes, and amyloid deposits. This study demonstrates, for the first time, that the Goodpasture antigen-binding protein (GPBP) binds to

  8. Neuroprotective Approaches in Experimental Models of β-Amyloid Neurotoxicity : Relevance to Alzheimer's Disease

    NARCIS (Netherlands)

    Harkany, Tibor; Hortobágyi, Tibor; Sasvári, Maria; Kónya, Csaba; Penke, Botond; Luiten, Paul G.M.; Nyakas, Csaba

    1999-01-01

    1. β-Amyloid peptides (Aβs) accumulate abundantly in the Alzheimer’s disease (AD) brain in areas subserving information acquisition and processing, and memory formation. Aβ fragments are produced in a process of abnormal proteolytic cleavage of their precursor, the amyloid precursor protein (APP). W

  9. THE EOSINOPHILIC MATERIAL IN ADENOMATOID ODONTOGENIC TUMOR ASSOCIATED WITH AMYLOID PROTEIN COMPONENT

    Institute of Scientific and Technical Information of China (English)

    SONG Bao-ping; LI Yong-mei; Haruo Okabe

    1999-01-01

    Objective: To investigate the relation between eosinophilic materials and amyloid P (AP) component in adenomatoid odontogenic tumor (AOT). Methods: The expression of amyloid proteins and basement membrane proteins, including type Ⅳ collagen, laminin and heparin sulfate proteoglycan (HSPG), in AOT were analyzed by immunohistochemical method. Results:Most eosinophilic droplets among tumor cells and some epithelial cells showed positive stain for AP component.The immunoreactions of type Ⅳ collagen and laminin were only found in blood vessels of this tumor. The tumor cells and eosinophilic materials in duct-like structures were constantly unstained for both amyloid and basement membrane proteins. Present results suggest that the nature and composition of eosinophilic droplets may differ from the eosinophilic layer in ductlike structures. This study first demonstrated that the amyloid-like deposition in AOT is associated with AP component by immunohistochemical method. It supported that AP component may be epithelial origin since the AP immunolocalization was found in tumor cells.

  10. Effect of catalpol on senile plaques and spatial learning and memory ability in amyloidprotein precursor/presenilin 1 double transgenic mice%梓醇对淀粉样蛋白前体/早老素1双转基因小鼠老年斑和学习记忆的影响

    Institute of Scientific and Technical Information of China (English)

    宋冲; 楚亚楠; 贺桂琼; 刘刚; 王凌唏; 周泽芬; 姚秋会

    2013-01-01

    目的 观察梓醇对淀粉样蛋白前体、早老素1(APP/PSI)双转基因小鼠老年斑和学习记忆能力的影响.方法 将3个月龄的APP/PS1双转基因小鼠按照随机数字表法分为梓醇治疗组和生理盐水对照组,每组10只,并以10只同月龄的相同遗传背景的C57小鼠作为正常对照组.用梓醇(每天5 mg/kg)和等量生理盐水腹腔注射阿尔茨海默病(AD)模型小鼠3周,应用免疫组织化学检测各组小鼠老年斑数量的变化;应用Morris水迷宫检测小鼠空间学习记忆能力的变化.结果 免疫组织化学结果显示:与生理盐水对照组(6.0±0.6)比较,梓醇治疗组小鼠老年斑数量(个)明显减少(2.3±0.7,t=3.500,P=0.025).行为学结果显示:(1)在可视平台实验中,3组小鼠找到平台的平均潜伏期和搜索的平均路径差异无统计学意义.(2)隐蔽平台下,梓醇治疗组小鼠找到平台的时间及搜索的路径较生理盐水对照组小鼠明显缩短;与正常对照组比较,差异无统计学意义.(3)在探索实验中,60 s内梓醇治疗组(6.4±0.5)小鼠穿越平台次数(次)明显高于生理盐水对照组(2.9±0.4,t=5.592,P=0.001),而与正常对照组(6.8±0.6)比较差异无统计学意义(t=0.418,P=0.682).结论 梓醇治疗能显著减少AD模型小鼠脑内老年斑数量,改善小鼠的空间学习记忆能力.%Objective To investigate whether catalpol affects senile plaque formation and spatial learning and memory ability in the amyloidprotein precursor/presenilin 1 (APP/PSI) double transgenic mice.Methods Three month-old APP/PS1 double transgenic mice were randomly divided into catalpoltreated and saline-treated groups (n =10),with C57 mice of the same age and genetic background as normal control group (n =10).The catalpol (in a dose of 5 mg · kg-1 · d-1) and the same amount of saline were peritoneally injected into Alzheimer' s disease (AD) model mice for 3 weeks.Immunohistochemical staining was performed to examine senile

  11. Amyloid Beta-Protein and Neural Network Dysfunction

    Directory of Open Access Journals (Sweden)

    Fernando Peña-Ortega

    2013-01-01

    Full Text Available Understanding the neural mechanisms underlying brain dysfunction induced by amyloid beta-protein (Aβ represents one of the major challenges for Alzheimer’s disease (AD research. The most evident symptom of AD is a severe decline in cognition. Cognitive processes, as any other brain function, arise from the activity of specific cell assemblies of interconnected neurons that generate neural network dynamics based on their intrinsic and synaptic properties. Thus, the origin of Aβ-induced cognitive dysfunction, and possibly AD-related cognitive decline, must be found in specific alterations in properties of these cells and their consequences in neural network dynamics. The well-known relationship between AD and alterations in the activity of several neural networks is reflected in the slowing of the electroencephalographic (EEG activity. Some features of the EEG slowing observed in AD, such as the diminished generation of different network oscillations, can be induced in vivo and in vitro upon Aβ application or by Aβ overproduction in transgenic models. This experimental approach offers the possibility to study the mechanisms involved in cognitive dysfunction produced by Aβ. This type of research may yield not only basic knowledge of neural network dysfunction associated with AD, but also novel options to treat this modern epidemic.

  12. Deposition of mouse amyloid beta in human APP/PS1 double and single AD model transgenic mice.

    NARCIS (Netherlands)

    Groen, T. van; Kiliaan, A.J.; Kadish, I.

    2006-01-01

    The deposition of amyloid beta (Abeta) peptides and neurofibrillary tangles are the two characteristic pathological features of Alzheimer's disease (AD). To investigate the relation between amyloid precursor protein (APP) production, amyloid beta deposition and the type of Abeta in deposits, i.e., h

  13. Specific Triazine Herbicides Induce Amyloid-beta(42) Production

    NARCIS (Netherlands)

    Portelius, Erik; Durieu, Emilie; Bodin, Marion; Cam, Morgane; Pannee, Josef; Leuxe, Charlotte; Mabondzo, Aloise; Oumata, Nassima; Galons, Herve; Lee, Jung Yeol; Chang, Young-Tae; Stuber, Kathrin; Koch, Philipp; Fontaine, Gaelle; Potier, Marie-Claude; Manousopoulou, Antigoni; Garbis, Spiros D.; Covaci, Adrian; Van Dam, Debby; De Deyn, Peter; Karg, Frank; Flajolet, Marc; Omori, Chiori; Hata, Saori; Suzuki, Toshiharu; Blennow, Kaj; Zetterberg, Henrik; Meijer, Laurent

    2016-01-01

    Proteolytic cleavage of the amyloid-beta protein precursor (A beta PP) ecretases leads to extracellular release of amyloid-beta (A beta) peptides. Increased production of A beta(42) over A beta(40) and aggregation into oligomers and plaques constitute an Alzheimer's disease (AD) hallmark. Identifyin

  14. Comparison of the aggregation of homologous β2-microglobulin variants reveals protein solubility as a key determinant of amyloid formation.

    Science.gov (United States)

    Pashley, Clare L; Hewitt, Eric W; Radford, Sheena E

    2016-02-13

    The mouse and human β2-microglobulin protein orthologs are 70% identical in sequence and share 88% sequence similarity. These proteins are predicted by various algorithms to have similar aggregation and amyloid propensities. However, whilst human β2m (hβ2m) forms amyloid-like fibrils in denaturing conditions (e.g. pH2.5) in the absence of NaCl, mouse β2m (mβ2m) requires the addition of 0.3M NaCl to cause fibrillation. Here, the factors which give rise to this difference in amyloid propensity are investigated. We utilise structural and mutational analyses, fibril growth kinetics and solubility measurements under a range of pH and salt conditions, to determine why these two proteins have different amyloid propensities. The results show that, although other factors influence the fibril growth kinetics, a striking difference in the solubility of the proteins is a key determinant of the different amyloidogenicity of hβ2m and mβ2m. The relationship between protein solubility and lag time of amyloid formation is not captured by current aggregation or amyloid prediction algorithms, indicating a need to better understand the role of solubility on the lag time of amyloid formation. The results demonstrate the key contribution of protein solubility in determining amyloid propensity and lag time of amyloid formation, highlighting how small differences in protein sequence can have dramatic effects on amyloid formation.

  15. Transmembrane amyloid-related proteins in CSF as potential biomarkers for Alzheimer’s disease

    Directory of Open Access Journals (Sweden)

    Inmaculada eLopez-Font

    2015-06-01

    Full Text Available In the continuing search for new cerebrospinal fluid (CSF biomarkers for Alzheimer’s disease (AD, reasonable candidates are the secretase enzymes involved in the processing of the amyloid precursor protein (APP, as well as the large proteolytic cleavage fragments sAPPα and sAPPβ. The enzymatic activities of some of these secretases, such as BACE1 and TACE, have been investigated as potential AD biomarkers, and it has been assumed that these activities present in human CSF result from the soluble truncated forms of the membrane-bound enzymes. However, we and others recently identified soluble forms of BACE1 and APP in CSF containing the intracellular domains, as well as the multi-pass transmembrane presenilin-1 (PS1 and other subunits of γ-secretase. We also review recent findings that suggest that most of these soluble transmembrane proteins could display self-association properties based on hydrophobic and/or ionic interactions leading to the formation of heteromeric complexes. The oligomerization state of these potential new biomarkers needs to be taken into consideration for assessing their real potential as CSF biomarkers for AD by adequate molecular tools.

  16. Constant region of a kappa III immunoglobulin light chain as a major AL-amyloid protein

    DEFF Research Database (Denmark)

    Engvig, J P; Olsen, K E; Gislefoss, R E

    1998-01-01

    and the corresponding AL protein as a kappa III immunoglobulin light chain from material of a patient with systemic AL-amyloidosis presenting as a local inguinal tumour. The two proteins showed some unique features. The major part of the AL amyloid fibril protein consisted of C-terminal fragments of the Bence...

  17. Insights into the variability of nucleated amyloid polymerization by a minimalistic model of stochastic protein assembly

    Science.gov (United States)

    Eugène, Sarah; Xue, Wei-Feng; Robert, Philippe; Doumic, Marie

    2016-05-01

    Self-assembly of proteins into amyloid aggregates is an important biological phenomenon associated with human diseases such as Alzheimer's disease. Amyloid fibrils also have potential applications in nano-engineering of biomaterials. The kinetics of amyloid assembly show an exponential growth phase preceded by a lag phase, variable in duration as seen in bulk experiments and experiments that mimic the small volumes of cells. Here, to investigate the origins and the properties of the observed variability in the lag phase of amyloid assembly currently not accounted for by deterministic nucleation dependent mechanisms, we formulate a new stochastic minimal model that is capable of describing the characteristics of amyloid growth curves despite its simplicity. We then solve the stochastic differential equations of our model and give mathematical proof of a central limit theorem for the sample growth trajectories of the nucleated aggregation process. These results give an asymptotic description for our simple model, from which closed form analytical results capable of describing and predicting the variability of nucleated amyloid assembly were derived. We also demonstrate the application of our results to inform experiments in a conceptually friendly and clear fashion. Our model offers a new perspective and paves the way for a new and efficient approach on extracting vital information regarding the key initial events of amyloid formation.

  18. Self-assembling of amyloid-like proteins

    Energy Technology Data Exchange (ETDEWEB)

    Sales, E.M.; Barbosa, L.R.S.; Itri, R. [Universidade de Sao Paulo (USP), SP (Brazil); Damalio, J.C.P.; Araujo, A.P.U. [Universidade de Sao Paulo (USP-SC), Sao Carlos, SP (Brazil); Spinozzi, F.; Mariani, P. [Universita Politecnica delle Marche, Ancona (Italy)

    2012-07-01

    Full text: Septins are proteins from the GTP-binding family and participate in cell division cycle performing functions such as secretion and cytoskeletal division. They can also be found in neurodegenerative conditions as Alzheimers and Parkinson's diseases, forming highly organized fiber-like aggregates known as amyloids. In this work, we used small angle x-ray scattering (SAXS) to investigate the formation and time evolution of septins aggregates under the influence of temperature and concentration. The SAXS measurements were performed with the GTPase domain of human Septin 2 (SEPT2G) at 0.5 and 1 mg/mL and temperatures between 4 and 45 deg C. At 0.5 mg/mL and 4 deg C, the protein self-aggregates as a dimer, being stable over one hour of observation. When the temperature was increased to 15 deg C, the results demonstrate that cylinder-like aggregates are formed and coexist with some dimer population and a small amount of larger aggregates. However, the number of very large aggregates increases with time concomitantly with the decrease of cylinder amount in the solution. At 37 deg C cylinder-like aggregates are not longer present in solution, whereas a significant amount of dimers decreases from 50% to 20% in less than 1 hour. At 45 deg C such an effect is even more accentuated: the percentage of dimers is only 6% in solution into a favor of 94% of very larger aggregates. When we analyze the protein at 1 mg/mL, at 4 deg C cylinder-like aggregates (36 nm-long and 12 nm-cross section) are already formed, coexisting with dimers and, as occurred for lower concentration, the two populations remained unchanged over one hour of observation. Out results also indicate that the dimensions of these cylinders increase with the concentration and the percentage of cylinders and larger aggregates are higher than those found for 0.5 mg/mL. In conclusion, our results showed the coexistence of dimers of SEPT2G with small fibers and larger aggregates in solution that evolve

  19. HIV Tat protein and amyloid-β peptide form multifibrillar structures that cause neurotoxicity.

    Science.gov (United States)

    Hategan, Alina; Bianchet, Mario A; Steiner, Joseph; Karnaukhova, Elena; Masliah, Eliezer; Fields, Adam; Lee, Myoung-Hwa; Dickens, Alex M; Haughey, Norman; Dimitriadis, Emilios K; Nath, Avindra

    2017-02-20

    Deposition of amyloid-β plaques is increased in the brains of HIV-infected individuals, and the HIV transactivator of transcription (Tat) protein affects amyloidogenesis through several indirect mechanisms. Here, we investigated direct interactions between Tat and amyloid-β peptide. Our in vitro studies showed that in the presence of Tat, uniform amyloid fibrils become double twisted fibrils and further form populations of thick unstructured filaments and aggregates. Specifically, Tat binding to the exterior surfaces of the Aβ fibrils increases β-sheet formation and lateral aggregation into thick multifibrillar structures, thus producing fibers with increased rigidity and mechanical resistance. Furthermore, Tat and Aβ aggregates in complex synergistically induced neurotoxicity both in vitro and in animal models. Increased rigidity and mechanical resistance of the amyloid-β-Tat complexes coupled with stronger adhesion due to the presence of Tat in the fibrils may account for increased damage, potentially through pore formation in membranes.

  20. Serum amyloid A and protein AA: molecular mechanisms of a transmissible amyloidosis.

    Science.gov (United States)

    Westermark, Gunilla T; Westermark, Per

    2009-08-20

    Systemic AA-amyloidosis is a complication of chronic inflammatory diseases and the fibril protein AA derives from the acute phase reactant serum AA. AA-amyloidosis can be induced in mice by an inflammatory challenge. The lag phase before amyloid develops can be dramatically shortened by administration of a small amount of amyloid fibrils. Systemic AA-amyloidosis is transmissible in mice and may be so in humans. Since transmission can cross species barriers it is possible that AA-amyloidosis can be induced by amyloid in food, e.g. foie gras. In mice, development of AA-amyloidosis can also be accelerated by other components with amyloid-like properties. A new possible risk factor may appear with synthetically made fibrils from short peptides, constructed for tissue repair.

  1. AMYLOID-β PEPTIDE BINDS TO MICROTUBULE-ASSOCIATED PROTEIN 1B (MAP1B)

    Science.gov (United States)

    Gevorkian, Goar; Gonzalez-Noriega, Alfonso; Acero, Gonzalo; Ordoñez, Jorge; Michalak, Colette; Munguia, Maria Elena; Govezensky, Tzipe; Cribbs, David H.; Manoutcharian, Karen

    2008-01-01

    Extracellular and intraneuronal formation of amyloid-beta aggregates have been demonstrated to be involved in the pathogenesis of Alzheimer’s disease. However, the precise mechanism of amyloid-beta neurotoxicity is not completely understood. Previous studies suggest that binding of amyloid-beta to a number of targets have deleterious effects on cellular functions. In the present study we have shown for the first time that amyloid-beta 1-42 bound to a peptide comprising the microtubule binding domain of the heavy chain of microtubule-associated protein 1B by the screening of a human brain cDNA library expressed on M13 phage. This interaction may explain, in part, the loss of neuronal cytoskeletal integrity, impairment of microtubule-dependent transport and synaptic dysfunction observed previously in Alzheimer’s disease. PMID:18079022

  2. Biotechnologically engineered protein binders for applications in amyloid diseases.

    Science.gov (United States)

    Haupt, Christian; Fändrich, Marcus

    2014-10-01

    The aberrant self-assembly of polypeptide chains into amyloid structures is a common phenomenon in several neurodegenerative diseases, systemic amyloidosis, and 'normal' aging. Improvements in laboratory-scale detection of these structures, their clinical diagnosis, and the treatment of disease likely depend on the advent of new molecules that recognize particular states or induce their clearance in vivo. This review will describe what biotechnology can do to generate proteinaceous amyloid-binders, explain their molecular recognition mechanisms, and summarize possibilities to functionalize further these ligands for specific applications.

  3. Influence of Adsorption on Proteins and Amyloid Detection by Silicon Nitride Nanopore.

    Science.gov (United States)

    Balme, Sébastien; Coulon, Pierre Eugène; Lepoitevin, Mathilde; Charlot, Benoît; Yandrapalli, Naresh; Favard, Cyril; Muriaux, Delphine; Bechelany, Mikhael; Janot, Jean-Marc

    2016-09-01

    For the past 2 decades, emerging single-nanopore technologies have opened the route to multiple sensing applications. Besides DNA sensing, the identification of proteins and amyloids is a promising field for early diagnosis. However, the influence of the interactions between the nanopore surface and proteins should be taken into account. In this work, we have selected three proteins (avidin, lysozyme, and IgG) that exhibit different affinities with the SiNx surface, and we have also examined lysozyme amyloid. Our results show that the piranha treatment of SiNx significantly decreases protein adsorption. Moreover, we have successfully detected all proteins (pore diameter 17 nm) and shown the possibility of discriminating between denatured lysozyme and its amyloid. For all proteins, the capture rates are lower than expected, and we evidence that they are correlated with the affinity of proteins to the surface. Our result confirms that proteins interacting only with the nanopore surface wall stay long enough to be detected. For lysozyme amyloid, we show that the use of the nanopore is suitable for determining the number of monomer units even if only the proteins interacting with the nanopore are detected.

  4. Extended analysis of AL-amyloid protein from abdominal wall subcutaneous fat biopsy

    DEFF Research Database (Denmark)

    Olsen, K E; Sletten, K; Westermark, Per

    1998-01-01

    a subcutaneous fat tissue biopsy and submitted to extended protein separation, typing and amino acid sequence analyses. The AL-protein belonged to the rare immunoglobulin light chain kappa, subtype kappa IV and contained unique amino acid substitutions, mostly in the highly preserved framework regions. The study...... shows that subcutaneous fat biopsies are useful sources of amyloid material for biochemical studies....

  5. Comparative investigation of B-Protein and its probable precursor

    Energy Technology Data Exchange (ETDEWEB)

    Schweikert, A.; Bucovaz, E.

    1987-05-01

    B-Protein, discovered in 1976 by Bucovaz, appears to be a general biological marker for the detection of cancer. An assay procedure was developed to detect B-Protein which involves the interaction of B-Protein with a specific radiolabeled protein named binding protein, a substructure of the coenzyme A-synthesizing protein complex (CoA-SPC) of Bakers' yeast. A protein which may be the precursor of B-Protein is present normally in serum, whereas, a modified or altered protein, designated B-Protein, is present in the serum of cancer patients. Analysis of B-Protein and its relationship with the normal serum protein demonstrates a difference in solubility between B-Protein and the normal counterpart. Although physiochemical characteristics between both are very similar, i.e., electrophoretic mobility, molecular weight, pI, immunological recognition, there appears to be minor differences in the carbohydrate moiety of B-Protein as demonstrated by periodic acid-Schiff base staining and the binding of Wheat Germ Lectin. Lipid content has also been examined but has not been associated with the difference in solubility. Currently, the difference in B-Protein and its normal protein counterpart appears to be related to conformational differences in the tertiary structures.

  6. Metabolism of β-amyloid precursor protein, expressions of its related enzymes and effect of pioglitazone intervention in the brain of insulin resistance rats%胰岛素抵抗大鼠脑组织APP代谢及其相关酶的表达及吡格列酮的干预效果

    Institute of Scientific and Technical Information of China (English)

    袁树华; 高顺宗; 刘雪平; 郝跃伟; 赵婷婷; 侯亮

    2009-01-01

    目的 观察胰岛素抵抗(IR)大鼠脑组织β-淀粉样蛋白(Aβ)、淀粉样前体蛋白(APP)及其代谢相关酶的表达及吡格列酮(PIO)的干预效果.方法从45只Wistar大鼠中随机选取10只作为对照组(NC组),35只给予10%果糖水诱发胰岛素抵抗,4周后根据胰岛素抵抗指数(IRI),将制作成功的胰岛素抵抗模型26只大鼠随机分为IR组、PIO组.PIO组灌服吡格列酮(10 mg·kg~(-1)·d~(-1))12周,IR组和NC组给予相同体积的生理盐水.免疫组化法观察大鼠海马Aβ42的表达;免疫印迹法检测大鼠脑APP、β-分泌酶(BACE1)、γ-分泌酶(PSI)的变化.结果IR组和PIO组大鼠海马Aβ42的表达明显高于NC组,与IR组相比,PIO组表达明显减低(P<0.01);与NC组相比,IR组和PIO组大鼠脑组织APP、BACE1及PS1的表达增高,PIO组表达较IR组减少(P<0.05).结论胰岛素抵抗大鼠脑组织通过上调BACE1、PS1活性,使Aβ42生成增加;吡格列酮能抑制BACE1、PS1的表达,减少Aβ42生成.%Objective To investigate the expressions of β-amyloid (Aβ), amyloid precmsor protein (APP) and its metabohsm-related enzymes, and to explore the effect of pioglitazone (PIO) intervention in the brain of insulin resistance rats. Methods Of 45 Wistar male rats, 10 were randomly chosen as the control group (NC group), and the others were given 10% fructose for 4 weeks to develop the insulin resistance (IR) model. 26 IR rats were randomly divided into the IR group(n = 13) and the PIO group (n= 13). The PIO group was given pioglitazone(10 mg·kg~(-1)·d~(-1) by gavage for 12 weeks, and the IR and NC groups were given an identical volume of physiological saline. Immunohistochemistry and Western blotting were employed to examine the level of Aβ42 in the hippoeampus and the changes of APP, β-secretase (BACE1) and γ-secretase (PSI) in the brain tissue, Re-suits Immunohistoehemistry results indicated that the optical density of Aβ42 in the hippocampus of the IR and PIO groups was

  7. Staphylococcal Bap Proteins Build Amyloid Scaffold Biofilm Matrices in Response to Environmental Signals.

    Science.gov (United States)

    Taglialegna, Agustina; Navarro, Susanna; Ventura, Salvador; Garnett, James A; Matthews, Steve; Penades, José R; Lasa, Iñigo; Valle, Jaione

    2016-06-01

    Biofilms are communities of bacteria that grow encased in an extracellular matrix that often contains proteins. The spatial organization and the molecular interactions between matrix scaffold proteins remain in most cases largely unknown. Here, we report that Bap protein of Staphylococcus aureus self-assembles into functional amyloid aggregates to build the biofilm matrix in response to environmental conditions. Specifically, Bap is processed and fragments containing at least the N-terminus of the protein become aggregation-prone and self-assemble into amyloid-like structures under acidic pHs and low concentrations of calcium. The molten globule-like state of Bap fragments is stabilized upon binding of the cation, hindering its self-assembly into amyloid fibers. These findings define a dual function for Bap, first as a sensor and then as a scaffold protein to promote biofilm development under specific environmental conditions. Since the pH-driven multicellular behavior mediated by Bap occurs in coagulase-negative staphylococci and many other bacteria exploit Bap-like proteins to build a biofilm matrix, the mechanism of amyloid-like aggregation described here may be widespread among pathogenic bacteria.

  8. Staphylococcal Bap Proteins Build Amyloid Scaffold Biofilm Matrices in Response to Environmental Signals

    Science.gov (United States)

    Taglialegna, Agustina; Navarro, Susanna; Ventura, Salvador; Garnett, James A.; Matthews, Steve; Penades, José R.; Lasa, Iñigo; Valle, Jaione

    2016-01-01

    Biofilms are communities of bacteria that grow encased in an extracellular matrix that often contains proteins. The spatial organization and the molecular interactions between matrix scaffold proteins remain in most cases largely unknown. Here, we report that Bap protein of Staphylococcus aureus self-assembles into functional amyloid aggregates to build the biofilm matrix in response to environmental conditions. Specifically, Bap is processed and fragments containing at least the N-terminus of the protein become aggregation-prone and self-assemble into amyloid-like structures under acidic pHs and low concentrations of calcium. The molten globule-like state of Bap fragments is stabilized upon binding of the cation, hindering its self-assembly into amyloid fibers. These findings define a dual function for Bap, first as a sensor and then as a scaffold protein to promote biofilm development under specific environmental conditions. Since the pH-driven multicellular behavior mediated by Bap occurs in coagulase-negative staphylococci and many other bacteria exploit Bap-like proteins to build a biofilm matrix, the mechanism of amyloid-like aggregation described here may be widespread among pathogenic bacteria. PMID:27327765

  9. Effects of phosphatidylinositol-3 kinase/serine threonine kinase pathway on expression of beta-site amyloid precursor protein cleaving enzyme-1 in the hippocampus neurons%胰岛素信号通路磷脂酰肌醇-3激酶/丝氨酸苏氨酸蛋白激酶对海马神经元β-淀粉样前体蛋白裂解酶1表达的影响

    Institute of Scientific and Technical Information of China (English)

    李洁颖; 晏勇; 蔡志友; 冯占辉; 张华; 吴芳; 孟涛; 代政伟

    2009-01-01

    目的 通过胰岛素和磷脂酰肌醇-3激酶(PDK)抑制剂渥曼青霉素(wortmannin,WORT)对PI3K/丝氨酸苏氨酸蛋白激酶(PDK/Akt)信号通路的激活和抑制作用,观察PI3K/Akt信号通路对海马神经元B-淀粉样前体蛋白裂解酶1(BACE1)表达的影响.方法 40只SD大鼠随机分为空白对照组、假手术组、胰岛素组和WORT组(每组10只),海马立体定向注射胰岛素和PI3K抑制剂WORT.免疫组织化学和Western blot法检测PI3K/Akt信号传导相关蛋白以及BACE1的表达水平.结果 注射胰岛素的海马PI3K信号通路下游信号分子较对照组:Akt表达增加(0.952±0.060与0.835±0.029,t=4.9150,P=0.0001),Akt set473位点磷酸化(pAkt)水平上调(0.800±0.075与0.657±0.025,t=4.5598,P=0.0002),糖原合成激酶-3α(GSK-3α)磷酸化水平降低(0.604±0.062与0.726±0. 041,t=3.5871,P=0.0018),而成熟的BACE1及其裂解产物β分泌酶C末端(β-CTF)表达下调.WORT组的PI3K下游信号分子Akt、pAkt表达明显被抑制,磷酸化GSK-3α表达增加,同时成熟的BACE1(1.004±0.096)和β-CTF(1.031±0.048)的表达较对照组(分别0.498±0.064,0.786±0.101)上调(分别t=11.5980,P=0.0000;t=4.2194,P=0.0004).结论 胰岛素信号通路PI3K/AKt可以调节BACE1的表达和活性并参与阿尔茨海默病的发病机制.%Objective To investigate the effect of phosphatidylinesitol-3 kinase/serine threonine kinase (PI3K/Akt) signaling pathway on expression of beta-site amyloid precursor protein cleaving enzyme-1 (BACE1) in the hippocampus neurons of rat brain. Methods Forty SD rats were randomly divided into 4 groups: blank control group, sham-operated group, insulin group and wortmannin group. Insulin or the specific inhibitor of PI3K, wortmannin was injected into hippocampus neurons to activate or inhibit the signaling pathway in insulin group or wortmannin group, respectively. Immunoprecipitation and Western blot were used to analyze the proteins levels of PI3K/Akt and BACE1. Results In insulin

  10. [Amyloid typing from formalin-fixed paraffin-embedded tissues using LMD-LC-MS/MS system].

    Science.gov (United States)

    Tasaki, Masayoshi; Obayashi, Konen; Ueda, Mitsuharu; Ando, Yukio

    2014-03-01

    Amyloidosis is one of the protein conformational disorders in which normally soluble proteins accumulate insoluble amyloid fibrils, leading to severe organ dysfunction. To date, 30 different amyloidogenic proteins have been reported. Immunohistochemistry (IHC) is usually used to identify the amyloid precursor protein, but the results may be inconclusive owing to a loss of epitopes or small amounts of amyloid deposits, comprising unknown amyloidogenic protein. Recently, laser microdissection (LMD)-liquid chromatography tandem mass spectrometry (LC-MS/MS) has been used in a novel method to identify amyloid precursor protein from amyloid-laden formalin-fixed paraffin embedded (FFPE) tissues. We describe the usefulness of the system for amyloid typing in this report.

  11. Elongation of mouse prion protein amyloid-like fibrils: effect of temperature and denaturant concentration.

    Directory of Open Access Journals (Sweden)

    Katazyna Milto

    Full Text Available Prion protein is known to have the ability to adopt a pathogenic conformation, which seems to be the basis for protein-only infectivity. The infectivity is based on self-replication of this pathogenic prion structure. One of possible mechanisms for such replication is the elongation of amyloid-like fibrils. We measured elongation kinetics and thermodynamics of mouse prion amyloid-like fibrils at different guanidine hydrochloride (GuHCl concentrations. Our data show that both increases in temperature and GuHCl concentration help unfold monomeric protein and thus accelerate elongation. Once the monomers are unfolded, further increases in temperature raise the rate of elongation, whereas the addition of GuHCl decreases it. We demonstrated a possible way to determine different activation energies of amyloid-like fibril elongation by using folded and unfolded protein molecules. This approach separates thermodynamic data for fibril-assisted monomer unfolding and for refolding and formation of amyloid-like structure.

  12. Diagnostic performance of amyloid A protein quantification in fat tissue of patients with clinical AA amyloidosis

    NARCIS (Netherlands)

    Hazenberg, Bouke P. C.; Bijzet, Johannes; Limburg, Pieter C.; Skinner, Martha; Hawkins, Philip N.; Butrimiene, Irena; Livneh, Avi; Lesnyak, Olga; Nasonov, Evgeney L.; Filipowicz-Sosnowska, Anna; Guel, Ahmet; Merlini, Giampaolo; Wiland, Piotr; Oezdogan, Huri; Gorevic, Peter D.; Ben Maiz, Hedi; Benson, Merrill D.; Direskeneli, Haner; Kaarela, Kalevi; Garceau, Denis; Hauck, Wendy; van Rijswijk, Martin

    2007-01-01

    Objective. Amyloid A protein quantification in fat tissue is a new immunochemical method for detecting AA amyloidosis, a rare but serious disease. The objective was to assess diagnostic performance in clinical AA amyloidosis. Methods. Abdominal subcutaneous fat tissue of patients with AA amyloidosis

  13. Structural basis for precursor protein-directed ribosomal peptide macrocyclization

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kunhua; Condurso, Heather L.; Li, Gengnan; Ding, Yousong; Bruner, Steven D. (Florida)

    2016-11-11

    Macrocyclization is a common feature of natural product biosynthetic pathways including the diverse family of ribosomal peptides. Microviridins are architecturally complex cyanobacterial ribosomal peptides that target proteases with potent reversible inhibition. The product structure is constructed via three macrocyclizations catalyzed sequentially by two members of the ATP-grasp family, a unique strategy for ribosomal peptide macrocyclization. Here we describe in detail the structural basis for the enzyme-catalyzed macrocyclizations in the microviridin J pathway of Microcystis aeruginosa. The macrocyclases MdnC and MdnB interact with a conserved α-helix of the precursor peptide using a novel precursor-peptide recognition mechanism. The results provide insight into the unique protein–protein interactions that are key to the chemistry, suggest an origin for the natural combinatorial synthesis of microviridin peptides, and provide a framework for future engineering efforts to generate designed compounds.

  14. Microglia, neuroinflammation, and beta-amyloid protein in Alzheimer's disease.

    Science.gov (United States)

    Cai, Zhiyou; Hussain, M Delwar; Yan, Liang-Jun

    2014-05-01

    Compelling evidence from basic molecular biology has demonstrated the dual roles of microglia in the pathogenesis of Alzheimer's disease (AD). On one hand, microglia are involved in AD pathogenesis by releasing inflammatory mediators such as inflammatory cytokines, complement components, chemokines, and free radicals that are all known to contribute to beta-amyloid (Aβ) production and accumulation. On the other hand, microglia are also known to play a beneficial role in generating anti-Aβ antibodies and stimulating clearance of amyloid plaques. Aβ itself, an inducer of microglia activation and neuroinflammation, has been considered as an underlying and unifying factor in the development of AD. A vicious cycle of inflammation has been formed between Aβ accumulation, activated microglia, and microglial inflammatory mediators, which enhance Aβ deposition and neuroinflammation. Thus, inhibiting the vicious cycle seems to be a promising treatment to restrain further development of AD. With increasing research efforts on microglia in AD, intervention of microglia activation and neuroinflammation in AD may provide a potential target for AD therapy in spite of the provisional failure of nonsteroidal antiinflammatory drugs in clinical trials.

  15. Membrane Incorporation, Channel Formation, and Disruption of Calcium Homeostasis by Alzheimer's β-Amyloid Protein

    Directory of Open Access Journals (Sweden)

    Masahiro Kawahara

    2011-01-01

    Full Text Available Oligomerization, conformational changes, and the consequent neurodegeneration of Alzheimer's β-amyloid protein (AβP play crucial roles in the pathogenesis of Alzheimer's disease (AD. Mounting evidence suggests that oligomeric AβPs cause the disruption of calcium homeostasis, eventually leading to neuronal death. We have demonstrated that oligomeric AβPs directly incorporate into neuronal membranes, form cation-sensitive ion channels (“amyloid channels”, and cause the disruption of calcium homeostasis via the amyloid channels. Other disease-related amyloidogenic proteins, such as prion protein in prion diseases or α-synuclein in dementia with Lewy bodies, exhibit similarities in the incorporation into membranes and the formation of calcium-permeable channels. Here, based on our experimental results and those of numerous other studies, we review the current understanding of the direct binding of AβP into membrane surfaces and the formation of calcium-permeable channels. The implication of composition of membrane lipids and the possible development of new drugs by influencing membrane properties and attenuating amyloid channels for the treatment and prevention of AD is also discussed.

  16. Endogenously generated amyloid β increases membrane fluidity in neural 2a cells

    Institute of Scientific and Technical Information of China (English)

    NIU Ying; SHENG BaiYang; SONG Bo; LIU LingLing; ZHANG XiuFang; ZHAO NanMing; GONG YanDao

    2009-01-01

    The effect of endogenously generated amyloid β on membrane fluidity was investigated in Neural 2a cells stably expressing Swedish mutant amyloid precursor protein (APPswe). Membrane fluidity was studied by fluorescence polarizability using 1,6-Diphenyl-1,3,5-Hexatriene (DPH) as the fluorescence probe. It was found that the membrane fluidity in APPswe cells was significantly higher than that in its wild type counterparts. Alleviating the effect of amyloid β either by y secretase activity inhibition or by amyloid antibody treatment decreased membrane fluidity, which indicated an important role of amyloid β in increasing membrane fluidity. Treatment using amyloid β channel blocker, tromethamine and NA4 suggested that channel formed by amyloid β on the cell membrane is a way through which amyloid β takes its membrane fluidizing effect.

  17. Neuroinflammation in Lyme neuroborreliosis affects amyloid metabolism

    Directory of Open Access Journals (Sweden)

    Anckarsäter Henrik

    2010-06-01

    Full Text Available Abstract Background The metabolism of amyloid precursor protein (APP and β-amyloid (Aβ is widely studied in Alzheimer's disease, where Aβ deposition and plaque development are essential components of the pathogenesis. However, the physiological role of amyloid in the adult nervous system remains largely unknown. We have previously found altered cerebral amyloid metabolism in other neuroinflammatory conditions. To further elucidate this, we investigated amyloid metabolism in patients with Lyme neuroborreliosis (LNB. Methods The first part of the study was a cross-sectional cohort study in 61 patients with acute facial palsy (19 with LNB and 42 with idiopathic facial paresis, Bell's palsy and 22 healthy controls. CSF was analysed for the β-amyloid peptides Aβ38, Aβ40 and Aβ42, and the amyloid precursor protein (APP isoforms α-sAPP and β-sAPP. CSF total-tau (T-tau, phosphorylated tau (P-tau and neurofilament protein (NFL were measured to monitor neural cell damage. The second part of the study was a prospective cohort-study in 26 LNB patients undergoing consecutive lumbar punctures before and after antibiotic treatment to study time-dependent dynamics of the biomarkers. Results In the cross-sectional study, LNB patients had lower levels of CSF α-sAPP, β-sAPP and P-tau, and higher levels of CSF NFL than healthy controls and patients with Bell's palsy. In the prospective study, LNB patients had low levels of CSF α-sAPP, β-sAPP and P-tau at baseline, which all increased towards normal at follow-up. Conclusions Amyloid metabolism is altered in LNB. CSF levels of α-sAPP, β-sAPP and P-tau are decreased in acute infection and increase after treatment. In combination with earlier findings in multiple sclerosis, cerebral SLE and HIV with cerebral engagement, this points to an influence of neuroinflammation on amyloid metabolism.

  18. Mink serum amyloid A protein. Expression and primary structure based on cDNA sequences.

    Science.gov (United States)

    Marhaug, G; Husby, G; Dowton, S B

    1990-06-15

    The nucleotide sequences of two mink serum amyloid A (SAA) cDNA clones have been analyzed, one (SAA1) 776 base pairs long and the other (SAA2) 552 base pairs long. Significant differences were discovered when derived amino acid sequences were compared with data for apoSAA isolated from high density lipoprotein. Previous studies of mink protein SAA and amyloid protein A (AA) suggest that only one SAA isotype is amyloidogenic. The cDNA clone for SAA2 defines the "amyloid prone" isotype while SAA1 is found only in serum. Mink SAA1 has alanine in position 10, isoleucine in positions 24, 67, and 71, lysine in position 27, and proline in position 105. Residue 10 in mink SAA2 is valine while arginine and asparagine are at positions 24 and 27, respectively, all characteristics of protein AA isolated from mink amyloid fibrils. Mink SAA2 also has valine in position 67, phenylalanine in position 71, and amino acid 105 is serine. It remains unknown why these six amino acid substitutions render SAA2 more amyloidogenic than SAA1. Eighteen hours after lipopolysaccharide stimulation, mink SAA mRNA is abundant in liver with relatively minor accumulations in brain and lung. Genes encoding both SAA isotypes are expressed in all three organs while no SAA mRNA was detectable in amyloid prone organs, including spleen and intestine, indicating that deposition of AA from locally synthesized SAA is unlikely. A third mRNA species (2.2 kilobases) was identified and hybridizes with cDNA probes for mink SAA1 and SAA2. In addition to a major primary translation product (molecular mass 14,400 Da) an additional product with molecular mass 28,000 Da was immunoprecipitable.

  19. Plasma beta amyloid and the risk of Alzheimer's disease in Down syndrome.

    NARCIS (Netherlands)

    Coppus, A.M.W.; Schuur, M.; Vergeer, J.; Janssens, A.C.; Oostra, B.A.; Verbeek, M.M.; Duijn, C.M. van

    2012-01-01

    Extracellular deposition of amyloid beta peptide (Abeta) has been implicated as a critical step in the pathogenesis of Alzheimer's disease (AD). In Down syndrome (DS), Alzheimer's disease is assumed to be caused by the triplication and overexpression of the gene for amyloid precursor protein (APP),

  20. The Acute-Phase Proteins Serum Amyloid A and C Reactive Protein in Transudates and Exudates

    Science.gov (United States)

    Okino, Alessandra M.; Bürger, Cristiani; Cardoso, Jefferson R.; Lavado, Edson L.; Lotufo, Paulo A.; Campa, Ana

    2006-01-01

    The distinction between exudates and transudates is very important in the patient management. Here we evaluate whether the acute-phase protein serum amyloid A (SAA), in comparison with C reactive protein (CRP) and total protein (TP), can be useful in this discrimination. CRP, SAA, and TP were determined in 36 exudate samples (27 pleural and 9 ascitic) and in 12 transudates (9 pleural and 3 ascitic). CRP, SAA, and TP were measured. SAA present in the exudate corresponded to 10% of the amount found in serum, that is, the exudate/serum ratio (E/S) was 0.10 ± 0.13. For comparison, the exudate/serum ratio for CRP and TP was 0.39 ± 0.37 and 0.68 ± 0.15, respectively. There was a strong positive correlation between serum and exudate SAA concentration (r = 0.764;p < 0.0001). The concentration of SAA in transudates was low and did not overlap with that found in exudates (0.02-0.21 versus 0.8–360.5 g/mL). SAA in pleural and ascitic exudates results mainly from leakage of the serum protein via the inflamed membrane. A comparison of the E/S ratio of SAA and CRP points SAA as a very good marker in discriminating between exudates and transudates. PMID:16864904

  1. Aβ42 Is Essential for Parenchymal and Vascular Amyloid Deposition in Mice

    OpenAIRE

    McGowan, Eileen; Pickford, Fiona; Kim, Jungsu; Onstead, Luisa; Eriksen, Jason; Yu, Cindy; Skipper, Lisa; Murphy, M. Paul; Beard, Jenny; Das, Pritam; Jansen,Karen; DeLucia, Michael; Lin, Wen-Lang; Dolios, Georgia; Wang, Rong

    2005-01-01

    Considerable circumstantial evidence suggests that Aβ42 is the initiating molecule in Alzheimer's disease (AD) pathogenesis. However, the absolute requirement for Aβ42 for amyloid deposition has never been demonstrated in vivo. We have addressed this by developing transgenic models that express Aβ1-40 or Aβ1-42 in the absence of human amyloid β protein precursor (APP) overexpression. Mice expressing high levels of Aβ1-40 do not develop overt amyloid pathology. In contrast, mice expressing low...

  2. Conformational landscape of an amyloid intra-cellular domain and Landau-Ginzburg-Wilson paradigm in protein dynamics.

    Science.gov (United States)

    Dai, Jin; Niemi, Antti J; He, Jianfeng

    2016-07-28

    The Landau-Ginzburg-Wilson paradigm is proposed as a framework, to investigate the conformational landscape of intrinsically unstructured proteins. A universal Cα-trace Landau free energy is deduced from general symmetry considerations, with the ensuing all-atom structure modeled using publicly available reconstruction programs Pulchra and Scwrl. As an example, the conformational stability of an amyloid precursor protein intra-cellular domain (AICD) is inspected; the reference conformation is the crystallographic structure with code 3DXC in Protein Data Bank (PDB) that describes a heterodimer of AICD and a nuclear multi-domain adaptor protein Fe65. Those conformations of AICD that correspond to local or near-local minima of the Landau free energy are identified. For this, the response of the original 3DXC conformation to variations in the ambient temperature is investigated, using the Glauber algorithm. The conclusion is that in isolation the AICD conformation in 3DXC must be unstable. A family of degenerate conformations that minimise the Landau free energy is identified, and it is proposed that the native state of an isolated AICD is a superposition of these conformations. The results are fully in line with the presumed intrinsically unstructured character of isolated AICD and should provide a basis for a systematic analysis of AICD structure in future NMR experiments.

  3. Conformational landscape of an amyloid intra-cellular domain and Landau-Ginzburg-Wilson paradigm in protein dynamics

    Science.gov (United States)

    Dai, Jin; Niemi, Antti J.; He, Jianfeng

    2016-07-01

    The Landau-Ginzburg-Wilson paradigm is proposed as a framework, to investigate the conformational landscape of intrinsically unstructured proteins. A universal Cα-trace Landau free energy is deduced from general symmetry considerations, with the ensuing all-atom structure modeled using publicly available reconstruction programs Pulchra and Scwrl. As an example, the conformational stability of an amyloid precursor protein intra-cellular domain (AICD) is inspected; the reference conformation is the crystallographic structure with code 3DXC in Protein Data Bank (PDB) that describes a heterodimer of AICD and a nuclear multi-domain adaptor protein Fe65. Those conformations of AICD that correspond to local or near-local minima of the Landau free energy are identified. For this, the response of the original 3DXC conformation to variations in the ambient temperature is investigated, using the Glauber algorithm. The conclusion is that in isolation the AICD conformation in 3DXC must be unstable. A family of degenerate conformations that minimise the Landau free energy is identified, and it is proposed that the native state of an isolated AICD is a superposition of these conformations. The results are fully in line with the presumed intrinsically unstructured character of isolated AICD and should provide a basis for a systematic analysis of AICD structure in future NMR experiments.

  4. Estrogen protects neuronal cells from amyloid beta-induced apoptosis via regulation of mitochondrial proteins and function

    Directory of Open Access Journals (Sweden)

    Iwamoto Sean

    2006-11-01

    Full Text Available Abstract Background Neurodegeneration in Alzheimer's disease is associated with increased apoptosis and parallels increased levels of amyloid beta, which can induce neuronal apoptosis. Estrogen exposure prior to neurotoxic insult of hippocampal neurons promotes neuronal defence and survival against neurodegenerative insults including amyloid beta. Although all underlying molecular mechanisms of amyloid beta neurotoxicity remain undetermined, mitochondrial dysfunction, including altered calcium homeostasis and Bcl-2 expression, are involved in neurodegenerative vulnerability. Results In this study, we investigated the mechanism of 17β-estradiol-induced prevention of amyloid beta-induced apoptosis of rat hippocampal neuronal cultures. Estradiol treatment prior to amyloid beta exposure significantly reduced the number of apoptotic neurons and the associated rise in resting intracellular calcium levels. Amyloid beta exposure provoked down regulation of a key antiapoptotic protein, Bcl-2, and resulted in mitochondrial translocation of Bax, a protein known to promote cell death, and subsequent release of cytochrome c. E2 pretreatment inhibited the amyloid beta-induced decrease in Bcl-2 expression, translocation of Bax to the mitochondria and subsequent release of cytochrome c. Further implicating the mitochondria as a target of estradiol action, in vivo estradiol treatment enhanced the respiratory function of whole brain mitochondria. In addition, estradiol pretreatment protected isolated mitochondria against calcium-induced loss of respiratory function. Conclusion Therefore, we propose that estradiol pretreatment protects against amyloid beta neurotoxicity by limiting mitochondrial dysfunction via activation of antiapoptotic mechanisms.

  5. Molecular simulations of beta-amyloid protein near hydrated lipids (PECASE).

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Aidan Patrick; Han, Kunwoo (Texas A& M University, College Station, TX); Ford, David M. (Texas A& M University, College Station, TX)

    2005-12-01

    We performed molecular dynamics simulations of beta-amyloid (A{beta}) protein and A{beta} fragment(31-42) in bulk water and near hydrated lipids to study the mechanism of neurotoxicity associated with the aggregation of the protein. We constructed full atomistic models using Cerius2 and ran simulations using LAMMPS. MD simulations with different conformations and positions of the protein fragment were performed. Thermodynamic properties were compared with previous literature and the results were analyzed. Longer simulations and data analyses based on the free energy profiles along the distance between the protein and the interface are ongoing.

  6. Protein corona composition of gold nanoparticles/nanorods affects amyloid beta fibrillation process

    Science.gov (United States)

    Mirsadeghi, Somayeh; Dinarvand, Rassoul; Ghahremani, Mohammad Hossein; Hormozi-Nezhad, Mohammad Reza; Mahmoudi, Zohreh; Hajipour, Mohammad Javad; Atyabi, Fatemeh; Ghavami, Mahdi; Mahmoudi, Morteza

    2015-03-01

    Protein fibrillation process (e.g., from amyloid beta (Aβ) and α-synuclein) is the main cause of several catastrophic neurodegenerative diseases such as Alzheimer's and Parkinson diseases. During the past few decades, nanoparticles (NPs) were recognized as one of the most promising tools for inhibiting the progress of the disease by controlling the fibrillation kinetic process; for instance, gold NPs have a strong capability to inhibit Aβ fibrillations. It is now well understood that a layer of biomolecules would cover the surface of NPs (so called ``protein corona'') upon the interaction of NPs with protein sources. Due to the fact that the biological species (e.g., cells and amyloidal proteins) ``see'' the protein corona coated NPs rather than the pristine coated particles, one should monitor the fibrillation process of amyloidal proteins in the presence of corona coated NPs (and not pristine coated ones). Therefore, the previously obtained data on NPs effects on the fibrillation process should be modified to achieve a more reliable and predictable in vivo results. Herein, we probed the effects of various gold NPs (with different sizes and shapes) on the fibrillation process of Aβ in the presence and absence of protein sources (i.e., serum and plasma). We found that the protein corona formed a shell at the surface of gold NPs, regardless of their size and shape, reducing the access of Aβ to the gold inhibitory surface and, therefore, affecting the rate of Aβ fibril formation. More specifically, the anti-fibrillation potencies of various corona coated gold NPs were strongly dependent on the protein source and their concentrations (10% serum/plasma (simulation of an in vitro milieu) and 100% serum/plasma (simulation of an in vivo milieu)).Protein fibrillation process (e.g., from amyloid beta (Aβ) and α-synuclein) is the main cause of several catastrophic neurodegenerative diseases such as Alzheimer's and Parkinson diseases. During the past few decades

  7. Automated solid-state NMR resonance assignment of protein microcrystals and amyloids

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Elena [Goethe University Frankfurt am Main, Center for Biomolecular Magnetic Resonance, Institute of Biophysical Chemistry (Germany); Gath, Julia [ETH Zurich, Physical Chemistry (Switzerland); Habenstein, Birgit [UMR 5086 CNRS/Universite de Lyon 1, Institut de Biologie et Chimie des Proteines (France); Ravotti, Francesco; Szekely, Kathrin; Huber, Matthias [ETH Zurich, Physical Chemistry (Switzerland); Buchner, Lena [Goethe University Frankfurt am Main, Center for Biomolecular Magnetic Resonance, Institute of Biophysical Chemistry (Germany); Boeckmann, Anja, E-mail: a.bockmann@ibcp.fr [UMR 5086 CNRS/Universite de Lyon 1, Institut de Biologie et Chimie des Proteines (France); Meier, Beat H., E-mail: beme@ethz.ch [ETH Zurich, Physical Chemistry (Switzerland); Guentert, Peter, E-mail: guentert@em.uni-frankfurt.de [Goethe University Frankfurt am Main, Center for Biomolecular Magnetic Resonance, Institute of Biophysical Chemistry (Germany)

    2013-07-15

    Solid-state NMR is an emerging structure determination technique for crystalline and non-crystalline protein assemblies, e.g., amyloids. Resonance assignment constitutes the first and often very time-consuming step to a structure. We present ssFLYA, a generally applicable algorithm for automatic assignment of protein solid-state NMR spectra. Application to microcrystals of ubiquitin and the Ure2 prion C-terminal domain, as well as amyloids of HET-s(218-289) and {alpha}-synuclein yielded 88-97 % correctness for the backbone and side-chain assignments that are classified as self-consistent by the algorithm, and 77-90 % correctness if also assignments classified as tentative by the algorithm are included.

  8. Beta-amyloid overload does not directly correlate with SAPK/JNK activation and tau protein phosphorylation in the cerebellar cortex of Ts65Dn mice.

    Science.gov (United States)

    Lomoio, Selene; Scherini, Elda; Necchi, Daniela

    2009-11-10

    It is known that in the nervous tissue beta-amyloid overproduction and its extracellular or intracellular deposition can activate mitogen-activated protein kinases involved in tau protein phosphorylation. Hyperphosphorylated tau is not more able to bind neuron microtubules, leading to their disassembly and axon degeneration. We have previously described that at 10 months of age in the cerebellum of Ts65Dn mice, which are partially trisomic for the chromosome 16 and are considered a valuable model for Down syndrome, Purkinje cells undergo axon degeneration. Taking into consideration that Ts65Dn mice carry three copies of the gene encoding for the amyloid precursor protein, to characterize potential signaling events triggering the degenerative phenomenon, specific antibodies were used to examine the role of beta-amyloid overload in the activation of the stress activated kinase/c-jun N-terminal kinase (SAPK/JNK) and tau protein phosphorylation in the cerebellar cortex of 12-month-old Ts65Dn mice. We found small extracellular deposits of beta-amyloid at the borderline between the granule cell layer and the white matter, i.e., in the vicinity of the area where calbindin immunostaining of Purkinje cell axons revealed clusters of newly formed terminals of injured axons. Moreover, intracellular deposits were present in the somata of Purkinje cells. The level of activation of SAPK/JNK was greatly increased. The activation occurred in the "pinceaux" made by basket interneuron axons at the axon hillock of Purkinje cells. Antibody directed against tau protein phosphorylated at Ser-396/Ser-404 revealed positive NG2 cells and Bergman fibers in the molecular layer and oligodendrocytes in the white matter. Data indicate that beta-amyloid extracellular deposits could have exerted a local cytotoxic effect, leading to Purkinje cell axon degeneration. The activation of SAPK/JNK in basket cell "pinceaux" may be a consequence of altered functionality of Purkinje cells and may represent

  9. Hydrolysis of the amyloid prion protein and nonpathogenic meat and bone meal by anaerobic thermophilic prokaryotes and streptomyces subspecies.

    Science.gov (United States)

    Tsiroulnikov, Kirill; Rezai, Human; Bonch-Osmolovskaya, Elisaveta; Nedkov, Peter; Gousterova, Adriana; Cueff, Valérie; Godfroy, Anne; Barbier, Georges; Métro, François; Chobert, Jean-Marc; Clayette, Pascal; Dormont, Dominique; Grosclaude, Jeanne; Haertlé, Thomas

    2004-10-06

    Transmissible spongiform encephalopathies are caused by accumulation of highly resistant misfolded amyloid prion protein PrPres and can be initiated by penetration of such pathogen molecules from infected tissue to intact organism. Decontamination of animal meal containing amyloid prion protein is proposed thanks to the use of proteolytic enzymes secreted by thermophilic bacteria Thermoanaerobacter, Thermosipho, and Thermococcus subsp. and mesophilic soil bacteria Streptomyces subsp. Keratins alpha and beta, which resemble amyloid structures, were used as the substrates for the screening for microorganisms able to grow on keratins and producing efficient proteases specific for hydrolysis of beta-sheeted proteic structures, hence amyloids. Secretion of keratin-degrading proteases was evidenced by a zymogram method. Enzymes from thermophilic strains VC13, VC15, and S290 and Streptomyces subsp. S6 were strongly active against amyloid recombinant ovine prion protein and animal meal proteins. The studied proteases displayed broad primary specificities hydrolyzing low molecular mass peptide model substrates. Strong amyloidolytic activity of detected proteases was confirmed by experiments of hydrolysis of PrPres in SAFs produced from brain homogenates of mice infected with the 6PB1 BSE strain. The proteases from Thermoanaerobacter subsp. S290 and Streptomyces subsp. S6 are the best candidates for neutralization/elimination of amyloids in meat and bone meal and other protein-containing substances and materials.

  10. Review: Protein folding pathology in domestic animals

    Institute of Scientific and Technical Information of China (English)

    GRUYSErik

    2004-01-01

    Fibrillar proteins form structural elements of cells and the extracellular matrix. Pathological lesions of fibrillar microanatomical structures, or secondary fibrillar changes in globular proteins are well known. A special group concerns histologically amorphous deposits, amyloid. The major characteristics of amyloid are: apple green birefringence after Congo red staining of histological sections, and non-branching 7-10nm thick fibrils on electron microscopy revealing a high content of cross beta pleated sheets. About 25 different types of amyloid have been characterised. In animals, AA-amyloid is the most frequent type. Other types of amyloid in animals represent: AIAPP (in cats), AApoAⅠ, AApoAⅡ, localised AL-amyloid, amyloid in odontogenic or mammary tumors and amyloid in the brain. In old dogs Aβ and in sheep APrPsc-amyloid can be encountered. AA-amyloidosis is a systemic disorder with a precursor in blood, acute phase serum amyloid A (SAA). In chronic inflammatory processes AA-amyloid can be deposited. A rapid crystallization of SAA to amyloid fibrils on small beta-sheeted fragments, the ‘amyloid enhancing factor' (AEF), is known and the AEF has been shown to penetrate the enteric barrier. Amyloid fibrils can aggregate from various precursor proteins in vitro in particular at acidic pH and when proteolytic fragments are formed. Molecular chaperones influence this process. Tissue data point to amyloid fibrillogenesis in lysosomes and near cell surfaces. A comparison can be made of the fibrillogenesis in prion diseases and in enhanced AA-amyloidosis. In the reactive form, acute phase SAA is the supply of the precursor protein, whereas in the prion diseases, cell membrane proteins form a structural source. AI3-amyloid in brain tissue of aged dogs showing signs of dementia forms a canine counterpart of senile dementia of the Alzheimer type (ccSDAT) in man. Misfolded proteins remain potential food hazards. Developments concerning prevention of amyloidogenesis

  11. Aβ42 Is Essential for Parenchymal and Vascular Amyloid Deposition in Mice

    Science.gov (United States)

    McGowan, Eileen; Onstead, Luisa; Eriksen, Jason; Yu, Cindy; Skipper, Lisa; Murphy, M. Paul; Beard, Jenny; Das, Pritam; Jansen, Karen; DeLucia, Michael; Lin, Wen-Lang; Dolios, Georgia; Wang, Rong; Eckman, Christopher B.; Dickson, Dennis W.; Hutton, Mike; Hardy, John; Golde, Todd

    2005-01-01

    Summary Considerable circumstantial evidence suggests that Aβ42 is the initiating molecule in Alzheimer's disease (AD) pathogenesis. However, the absolute requirement for Aβ42 for amyloid deposition has never been demonstrated in vivo. We have addressed this by developing transgenic models that express Aβ1-40 or Aβ1-42 in the absence of human amyloid β protein precursor (APP) overexpression. Mice expressing high levels of Aβ1-40 do not develop overt amyloid pathology. In contrast, mice expressing lower levels of Aβ1-42 accumulate insoluble Aβ1-42 and develop compact amyloid plaques, congophilic amyloid angiopathy (CAA), and diffuse Aβ deposits. When mice expressing Aβ1-42 are crossed with mutant APP (Tg2576) mice, there is also a massive increase in amyloid deposition. These data establish that Aβ1-42 is essential for amyloid deposition in the parenchyma and also in vessels. PMID:16039562

  12. The Effect of Glycosaminoglycans (GAGs on Amyloid Aggregation and Toxicity

    Directory of Open Access Journals (Sweden)

    Clara Iannuzzi

    2015-02-01

    Full Text Available Amyloidosis is a protein folding disorder in which normally soluble proteins are deposited extracellularly as insoluble fibrils, impairing tissue structure and function. Charged polyelectrolytes such as glycosaminoglycans (GAGs are frequently found associated with the proteinaceous deposits in tissues of patients affected by amyloid diseases. Experimental evidence indicate that they can play an active role in favoring amyloid fibril formation and stabilization. Binding of GAGs to amyloid fibrils occurs mainly through electrostatic interactions involving the negative polyelectrolyte charges and positively charged side chains residues of aggregating protein. Similarly to catalyst for reactions, GAGs favor aggregation, nucleation and amyloid fibril formation functioning as a structural templates for the self-assembly of highly cytotoxic oligomeric precursors, rich in β-sheets, into harmless amyloid fibrils. Moreover, the GAGs amyloid promoting activity can be facilitated through specific interactions via consensus binding sites between amyloid polypeptide and GAGs molecules. We review the effect of GAGs on amyloid deposition as well as proteins not strictly related to diseases. In addition, we consider the potential of the GAGs therapy in amyloidosis.

  13. Progress in the development of therapeutic antibodies targeting prion proteins and β-amyloid peptides

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Prion diseases and Alzheimer’s disease (AD) are characterized by protein misfolding, and can lead to dementia. However, prion diseases are infectious and transmissible, while AD is not. The similarities and differences between these diseases have led researchers to perform comparative studies. In the last 2 decades, progress has been made in immunotherapy using anti-prion protein and anti-β-amyloid antibodies. In this study, we review new ideas and strategies for therapeutic antibodies targeting prion diseases and AD through conformation dependence.

  14. Gc protein (vitamin D-binding protein): Gc genotyping and GcMAF precursor activity.

    Science.gov (United States)

    Nagasawa, Hideko; Uto, Yoshihiro; Sasaki, Hideyuki; Okamura, Natsuko; Murakami, Aya; Kubo, Shinichi; Kirk, Kenneth L; Hori, Hitoshi

    2005-01-01

    The Gc protein (human group-specific component (Gc), a vitamin D-binding protein or Gc globulin), has important physiological functions that include involvement in vitamin D transport and storage, scavenging of extracellular G-actin, enhancement of the chemotactic activity of C5a for neutrophils in inflammation and macrophage activation (mediated by a GalNAc-modified Gc protein (GcMAF)). In this review, the structure and function of the Gc protein is focused on especially with regard to Gc genotyping and GcMAF precursor activity. A discussion of the research strategy "GcMAF as a target for drug discovery" is included, based on our own research.

  15. Targeting vascular amyloid in arterioles of Alzheimer disease transgenic mice with amyloid β protein antibody-coated nanoparticles.

    Science.gov (United States)

    Poduslo, Joseph F; Hultman, Kristi L; Curran, Geoffry L; Preboske, Gregory M; Chamberlain, Ryan; Marjańska, Małgorzata; Garwood, Michael; Jack, Clifford R; Wengenack, Thomas M

    2011-08-01

    The relevance of cerebral amyloid angiopathy (CAA) to the pathogenesis of Alzheimer disease (AD) and dementia in general emphasizes the importance of developing novel targeting approaches for detecting and treating cerebrovascular amyloid (CVA) deposits. We developed a nanoparticle-based technology that uses a monoclonal antibody against fibrillar human amyloid-β42 that is surface coated onto a functionalized phospholipid monolayer. We demonstrate that this conjugated nanoparticle binds to CVA deposits in arterioles of AD transgenic mice (Tg2576) after infusion into the external carotid artery using 3 different approaches. The first 2 approaches use a blood vessel enrichment of homogenized brain and a leptomeningeal vessel preparation from thin tangential brain slices from the surface of the cerebral cortex. Targeting of CVA by the antibody-coated nanoparticle was visualized using fluorescent lissamine rhodamine-labeled phospholipids in the nanoparticles, which were compared with fluorescent staining of the endothelial cells and amyloid deposits using confocal laser scanning microscopy. The third approach used high-field strength magnetic resonance imaging of antibody-coated iron oxide nanoparticles after infusion into the external carotid artery. Dark foci of contrast enhancement in cortical arterioles were observed in T2*-weighted images of ex vivo AD mouse brains that correlated histologically with CVA deposits. The targeting ability of these nanoparticles to CVA provides opportunities for the prevention and treatment of CAA.

  16. Conformational stability of mammalian prion protein amyloid fibrils is dictated by a packing polymorphism within the core region.

    Science.gov (United States)

    Cobb, Nathan J; Apostol, Marcin I; Chen, Shugui; Smirnovas, Vytautas; Surewicz, Witold K

    2014-01-31

    Mammalian prion strains are believed to arise from the propagation of distinct conformations of the misfolded prion protein PrP(Sc). One key operational parameter used to define differences between strains has been conformational stability of PrP(Sc) as defined by resistance to thermal and/or chemical denaturation. However, the structural basis of these stability differences is unknown. To bridge this gap, we have generated two strains of recombinant human prion protein amyloid fibrils that show dramatic differences in conformational stability and have characterized them by a number of biophysical methods. Backbone amide hydrogen/deuterium exchange experiments revealed that, in sharp contrast to previously studied strains of infectious amyloid formed from the yeast prion protein Sup35, differences in β-sheet core size do not underlie differences in conformational stability between strains of mammalian prion protein amyloid. Instead, these stability differences appear to be dictated by distinct packing arrangements (i.e. steric zipper interfaces) within the amyloid core, as indicated by distinct x-ray fiber diffraction patterns and large strain-dependent differences in hydrogen/deuterium exchange kinetics for histidine side chains within the core region. Although this study was limited to synthetic prion protein amyloid fibrils, a similar structural basis for strain-dependent conformational stability may apply to brain-derived PrP(Sc), especially because large strain-specific differences in PrP(Sc) stability are often observed despite a similar size of the PrP(Sc) core region.

  17. Conformational Stability of Mammalian Prion Protein Amyloid Fibrils Is Dictated by a Packing Polymorphism within the Core Region*

    Science.gov (United States)

    Cobb, Nathan J.; Apostol, Marcin I.; Chen, Shugui; Smirnovas, Vytautas; Surewicz, Witold K.

    2014-01-01

    Mammalian prion strains are believed to arise from the propagation of distinct conformations of the misfolded prion protein PrPSc. One key operational parameter used to define differences between strains has been conformational stability of PrPSc as defined by resistance to thermal and/or chemical denaturation. However, the structural basis of these stability differences is unknown. To bridge this gap, we have generated two strains of recombinant human prion protein amyloid fibrils that show dramatic differences in conformational stability and have characterized them by a number of biophysical methods. Backbone amide hydrogen/deuterium exchange experiments revealed that, in sharp contrast to previously studied strains of infectious amyloid formed from the yeast prion protein Sup35, differences in β-sheet core size do not underlie differences in conformational stability between strains of mammalian prion protein amyloid. Instead, these stability differences appear to be dictated by distinct packing arrangements (i.e. steric zipper interfaces) within the amyloid core, as indicated by distinct x-ray fiber diffraction patterns and large strain-dependent differences in hydrogen/deuterium exchange kinetics for histidine side chains within the core region. Although this study was limited to synthetic prion protein amyloid fibrils, a similar structural basis for strain-dependent conformational stability may apply to brain-derived PrPSc, especially because large strain-specific differences in PrPSc stability are often observed despite a similar size of the PrPSc core region. PMID:24338015

  18. Vaccinium uliginosum L. Improves Amyloid β Protein-Induced Learning and Memory Impairment in Alzheimer's Disease in Mice.

    Science.gov (United States)

    Choi, Yoon-Hee; Kwon, Hyuck-Se; Shin, Se-Gye; Chung, Cha-Kwon

    2014-12-01

    The present study investigated the effects of Vaccinium uliginosum L. (bilberry) on the learning and memory impairments induced by amyloidprotein (AβP) 1-42. ICR Swiss mice were divided into 4 groups: the control (Aβ40-1A), control with 5% bilberry group (Aβ40-1B), amyloid β protein 1-42 treated group (Aβ1-42A), and Aβ1-42 with 5% bilberry group (Aβ1-42B). The control was treated with amyloid β-protein 40-1 for placebo effect, and Alzheimer's disease (AD) group was treated with amyloid β-protein 1-42. Amyloid β-protein 1-42 was intracerebroventricular (ICV) micro injected into the hippocampus in 35% acetonitrile and 0.1% trifluoroacetic acid. Although bilberry added groups tended to decrease the finding time of hidden platform, no statistical significance was found. On the other hand, escape latencies of AβP injected mice were extended compared to that of Aβ40-1. In the Probe test, bilberry added Aβ1-42B group showed a significant (Pmemory compared to Aβ40-1 control group. In passive avoidance test, bilberry significantly (Pimprove memory and learning capability in chemically induced Alzheimer's disease in experimental animal models.

  19. Effects of Shouwu-Yizhi capsule on learning and memory and the expressions of presenilin 1,β-amyloid precursor protein mRNAs in the hippocampus following cerebral ischemia reperfusion in rats%首乌益智胶囊对脑缺血再灌注大鼠学习记忆和海马β淀粉样前体蛋白、早老素1 mRNA表达的影响

    Institute of Scientific and Technical Information of China (English)

    陈超; 李长生; 杨晓妮; 程广清

    2014-01-01

    目的:探讨首乌益智胶囊对脑缺血再灌注大鼠学习记忆和早老素1(PS1)、β淀粉样前体蛋白(APP)mRNA表达的影响。方法80只大鼠按体质量随机分为假手术组、模型组、首乌益智胶囊组、脑复康组,每组20只。采用大脑中动脉闭塞法制作脑缺血再灌模型。造模后7 d,首乌益智胶囊组和脑复康组分别给予首乌益智胶囊溶液(52 mg/ml)、脑复康溶液(28 mg/ml)灌胃,均为1 ml/(100 g•d),共28 d,模型组和假手术组等体积生理盐水灌胃。采用Morris水迷宫评价学习和记忆;采用实时荧光定量PCR检测大鼠海马PS1和APP mRNA表达。结果水迷宫实验显示,模型组大鼠逃避潜伏期较假手术组[(12.98±0.70)s比(9.43±0.78)s]显著延长,穿越平台次数较假手术组[(5.08±0.39)次比(7.62±0.43)次]显著减少,首乌益智胶囊组逃避潜伏期较模型组[(9.77±0.58)s比(12.98±0.70)s]显著缩短(P均<0.01),穿越平台次数较模型组[(7.40±0.44)次比(5.08±0.39)次]显著增加(P均<0.01)。首乌益智胶囊组海马PS1和APP mRNA 表达[(0.99±0.01)比(1.08±0.03)]均较模型组[(1.06±0.03)比(1.12±0.04)]显著降低(P<0.05或0.01)。结论首乌益智胶囊可抑制脑缺血再灌大鼠海马PS1和APP mRNA表达,改善学习和记忆。%Objective To investigate the effects of Shouwu-Yizhi capsule on learning and memory, and the expressions of presenilin 1(PS1),β-amyloid precursor protein (APP) mRNAs in the hippocampus following cerebral ischemia reperfusion in rats. Methods Sprague–Dawley rats were randomly divided into a Shouwu-Yizhi group, a piracetam group, a model group, and a sham operation group with 20 rats in each group. Focal cerebral ischemia reperfusion model was induced by middle cerebral artery occlusion for 2 hours. Seven days after ischemia reperfusion, the rats in the Shouwu-Yizhi and piracetam groups were administered intragastrically Shouwu-Yizhi solution (52 mg/ml) and

  20. Intermolecular alignment in Y145Stop human prion protein amyloid fibrils probed by solid-state NMR spectroscopy.

    Science.gov (United States)

    Helmus, Jonathan J; Surewicz, Krystyna; Apostol, Marcin I; Surewicz, Witold K; Jaroniec, Christopher P

    2011-09-07

    The Y145Stop mutant of human prion protein, huPrP23-144, has been linked to PrP cerebral amyloid angiopathy, an inherited amyloid disease, and also serves as a valuable in vitro model for investigating the molecular basis of amyloid strains. Prior studies of huPrP23-144 amyloid by magic-angle-spinning (MAS) solid-state NMR spectroscopy revealed a compact β-rich amyloid core region near the C-terminus and an unstructured N-terminal domain. Here, with the focus on understanding the higher-order architecture of huPrP23-144 fibrils, we probed the intermolecular alignment of β-strands within the amyloid core using MAS NMR techniques and fibrils formed from equimolar mixtures of (15)N-labeled protein and (13)C-huPrP23-144 prepared with [1,3-(13)C(2)] or [2-(13)C]glycerol. Numerous intermolecular correlations involving backbone atoms observed in 2D (15)N-(13)C spectra unequivocally suggest an overall parallel in-register alignment of the β-sheet core. Additional experiments that report on intermolecular (15)N-(13)CO and (15)N-(13)Cα dipolar couplings yielded an estimated strand spacing that is within ∼10% of the distances of 4.7-4.8 Å typical for parallel β-sheets.

  1. Opioid precursor protein isoform is targeted to the cell nuclei in the human brain

    NARCIS (Netherlands)

    Kononenko, Olga; Bazov, Igor; Watanabe, Hiroyuki; Gerashchenko, Ganna; Dyachok, Oleg; Verbeek, Dineke S; Alkass, Kanar; Druid, Henrik; Andersson, Malin; Mulder, Jan; Svenningsen, Åsa Fex; Rajkowska, Grazyna; Stockmeier, Craig A; Krishtal, Oleg; Yakovleva, Tatiana; Bakalkin, Georgy

    2017-01-01

    BACKGROUND: Neuropeptide precursors are traditionally viewed as proteins giving rise to small neuropeptide molecules. Prodynorphin (PDYN) is the precursor protein to dynorphins, endogenous ligands for the κ-opioid receptor. Alternative mRNA splicing of neuropeptide genes may regulate cell- and tissu

  2. OPIOID PRECURSOR PROTEIN ISOFORM IS TARGETED TO THE CELL NUCLEI IN THE HUMAN BRAIN

    DEFF Research Database (Denmark)

    Kononenko, Olga; Bazov, Igor; Watanabe, Hiroyuki;

    2016-01-01

    Neuropeptide precursors are traditionally viewed as proteins giving rise to small neuropeptide molecules. Prodynorphin (PDYN) is the precursor protein to dynorphins, endogenous ligands for the κ-opioid receptor. We here describe two novel splicing variants of human PDYN mRNA. Expression of one...

  3. Oxidative stress induces macroautophagy of amyloid beta-protein and ensuing apoptosis

    DEFF Research Database (Denmark)

    Zheng, Lin; Kågedal, Katarina; Dehvari, Nodi;

    2009-01-01

    There is increasing evidence for the toxicity of intracellular amyloid beta-protein (Abeta) to neurons and the involvement of lysosomes in this process in Alzheimer disease (AD). We have recently shown that oxidative stress, a recognized determinant of AD, enhances macroautophagy and leads...... to intralysosomal accumulation of Abeta in cultured neuroblastoma cells. We hypothesized that oxidative stress promotes AD by stimulating macroautophagy of Abeta that further may induce cell death by destabilizing lysosomal membranes. To investigate such possibility, we compared the effects of hyperoxia (40...

  4. A quantitative method for detecting deposits of amyloid A protein in aspirated fat tissue of patients with arthritis

    OpenAIRE

    Hazenberg, B.; Limburg, P; Bijzet, J.; VAN RIJSWIJK, M. H

    1999-01-01

    OBJECTIVE—To describe a new, quantitative, and reproducible method for detecting deposits of amyloid A protein in aspirated fat tissue and to compare it with smears stained with Congo red.
METHODS—After extraction of at least 30 mg of abdominal fat tissue in guanidine, the amyloid A protein concentration was measured by a monoclonal antibody-based sandwich ELISA.
RESULTS—The concentrations in 24 patients with arthritis and AA amyloidosis (median 236, range 1.1-8530 ng/mg tissue) were higher (...

  5. Specific binding of DNA to aggregated forms of Alzheimer's disease amyloid peptides.

    Science.gov (United States)

    Camero, Sergio; Ayuso, Jose M; Barrantes, Alejandro; Benítez, María J; Jiménez, Juan S

    2013-04-01

    Anomalous protein aggregation is closely associated to age-related mental illness. Extraneuronal plaques, mainly composed of aggregated amyloid peptides, are considered as hallmarks of Alzheimer's disease. According to the amyloid cascade hypothesis, this disease starts as a consequence of an abnormal processing of the amyloid precursor protein resulting in an excess of amyloid peptides. Nuclear localization of amyloid peptide aggregates together with amyloid-DNA interaction, have been repeatedly reported. In this paper we have used surface plasmon resonance and electron microscopy to study the structure and behavior of different peptides and proteins, including β-lactoglobulin, bovine serum albumin, myoglobin, histone, casein and the amyloid-β peptides related to Alzheimer's disease Aβ25-35 and Aβ1-40. The main purpose of this study is to investigate whether proneness to DNA interaction is a general property displayed by aggregated forms of proteins, or it is an interaction specifically related to the aggregated forms of those particular proteins and peptides related to neurodegenerative diseases. Our results reveal that those aggregates formed by amyloid peptides show a particular proneness to interact with DNA. They are the only aggregated structures capable of binding DNA, and show more affinity for DNA than for other polyanions like heparin and polyglutamic acid, therefore strengthening the hypothesis that amyloid peptides may, by means of interaction with nuclear DNA, contribute to the onset of Alzheimer's disease.

  6. Protein folding pathology in domestic animals

    Institute of Scientific and Technical Information of China (English)

    GRUYS Erik

    2004-01-01

    Fibrillar proteins form structural elements of cells and the extracellular matrix. Pathological lesions of fibrillar microanatomical structures, or secondary fibrillar changes in globular proteins are well known. A special group concerns histologically amorphous deposits, amyloid. The major characteristics of amyloid are: apple green birefringence after Congo red staining of histological sections, and non-branching 7-10 nm thick fibrils on electron microscopy revealing a high content of cross beta pleated sheets. About 25 different types of amyloid have been characterised. In animals,AA-amyloid is the most frequent type. Other types of amyloid in animals represent: AIAPP (in cats), AApoAⅠ, AApoAⅡ,localised AL-amyloid, amyloid in odontogenic or mammary tumors and amyloid in the brain. In old dogs Aβ and in sheep APrPsc-amyloid can be encountered. AA-amyloidosis is a systemic disorder with a precursor in blood, acute phase serum amyloid A (SAA). In chronic inflammatory processes AA-amyloid can be deposited. A rapid crystallization of SAA to shown to penetrate the enteric barrier. Amyloid fibrils can aggregate from various precursor proteins in vitro in particular at acidic pH and when proteolytic fragments are formed. Molecular chaperones influence this process. Tissue data point to amyloid fibrillogenesis in lysosomes and near cell surfaces. A comparison can be made of the fibrillogenesis in prion diseases and in enhanced AA-amyloidosis. In the reactive form, acute phase SAA is the supply of the precursor protein,whereas in tho prion diseases, cell membrane proteins form a structural source. Aβ-amyloid in brain tissue of aged dogs showing signs of dementia forms a canine counterpart of senile dementia of the Alzheimer type (ccSDAT) in man. Misfolded proteins remain potential food hazards. Developments concerning prevention of amyloidogenesis and therapy of amyloid deposits are shortly commented.

  7. APP蛋白家族胞内段释放与神经干细胞向神经元细胞定向分化的关系研究%Study on the Relationship between the Release of Intracellular Domain of AmyloidPrecursor Protein and Directional Differentiation of Neural Stem Cells into Neuron Cells

    Institute of Scientific and Technical Information of China (English)

    章建国; Amy Yong Chen Low; 杨武林

    2012-01-01

    [Objective] The research aimed to study the effects of the intracellular domain of APP family on the directional differentiation of neuron. [Method ] Neural stem cells were isolated and cultured in vitro, which were then transfected with plasmids containing the intracellular domains of APP family for overexpression. Their effects on the directional differentiation of neural stem cells into neurons were studied. [Result ] The over-expression of the intracellular domain of APP protein family can inhibit the differentiation of neural stem cells into neurons, and the effects of intracellular segments of APP and APLP2 were particularly significant. Mutagenesis experiments showed that it was necessary to release 31 amino acid terminal fragment through Capase hydrolysis in this process. The directional differentiation of neural stem cells into neuron cells was controlled through releasing APP-ICD31 by the intracellular domain of APP family. [Conclusion] This research further proved the relationship between APP protein and the incidence of Alzheimers disease,and provided new targets for the treatment of Alzheimers disease.%[目的]研究APP家族胞内段时神经细胞定向分化的影响.[方法]通过分离体外培养神经干细胞,转染导入APP蛋白家族胞内段以过表达后,研究其对神经干细胞向神经元定向分化的影响.[结果]APP家族蛋白胞内段的过表达可以抑制神经干细胞向神经元细胞的分化,其中APP和APLP2胞内段的影响尤为显著.突变试验表明,通过Capase水解释放末端31氧基酸片断是这个过程必需的.APP家族胞内段是通过释放APP-ICD31来抑制神经干细胞向神经元细胞的定向分化.[结论]该研究进一步证实了APP蛋白和老年痴呆病发生的联系,也为老年痴呆症的治疗提供新的靶点.

  8. Proteomic study of amyloid beta (25-35) peptide exposure to neuronal cells: Impact on APE1/Ref-1's protein-protein interaction.

    Science.gov (United States)

    Mantha, Anil K; Dhiman, Monisha; Taglialatela, Giulio; Perez-Polo, Regino J; Mitra, Sankar

    2012-06-01

    The genotoxic, extracellular accumulation of amyloid β (Aβ) protein and subsequent neuronal cell death are associated with Alzheimer's disease (AD). APE1/Ref-1, the predominant apurinic/apyrimidinic (AP) endonuclease and essential in eukaryotic cells, plays a central role in the base excision repair (BER) pathway for repairing oxidized and alkylated bases and single-strand breaks (SSBs) in DNA. APE1/Ref-1 is also involved in the redox activation of several trans-acting factors (TFs) in various cell types, but little is known about its role in neuronal functions. There is emerging evidence for APE1/Ref-1's role in neuronal cells vulnerable in AD and other neurodegenerative disorders, as reflected in its nuclear accumulation in AD brains. An increase in APE1/Ref-1 has been shown to enhance neuronal survival after oxidative stress. To address whether APE1/Ref-1 level or its association with other proteins is responsible for this protective effect, we used 2-D proteomic analyses and identified cytoskeleton elements (i.e., tropomodulin 3, tropomyosin alpha-3 chain), enzymes involved in energy metabolism (i.e., pyruvate kinase M2, N-acetyl transferase, sulfotransferase 1c), proteins involved in stress response (i.e., leucine-rich and death domain, anti-NGF30), and heterogeneous nuclear ribonucleoprotien-H (hnRNP-H) as being associated with APE1/Ref-1 in Aβ(25-35)-treated rat pheochromocytoma PC12 and human neuroblastoma SH-SY5Y cell lines, two common neuronal precursor lines used in Aβ neurotoxicity studies. Because the levels of some of these proteins are affected in the brains of AD patients, our study suggests a neuroprotective role for APE1/Ref-1 via its association with those proteins and modulating their cellular functions during Aβ-mediated neurotoxicity.

  9. Hybrid Amyloid Membranes for Continuous Flow Catalysis.

    Science.gov (United States)

    Bolisetty, Sreenath; Arcari, Mario; Adamcik, Jozef; Mezzenga, Raffaele

    2015-12-29

    Amyloid fibrils are promising nanomaterials for technological applications such as biosensors, tissue engineering, drug delivery, and optoelectronics. Here we show that amyloid-metal nanoparticle hybrids can be used both as efficient active materials for wet catalysis and as membranes for continuous flow catalysis applications. Initially, amyloid fibrils generated in vitro from the nontoxic β-lactoglobulin protein act as templates for the synthesis of gold and palladium metal nanoparticles from salt precursors. The resulting hybrids possess catalytic features as demonstrated by evaluating their activity in a model catalytic reaction in water, e.g., the reduction of 4-nitrophenol into 4-aminophenol, with the rate constant of the reduction increasing with the concentration of amyloid-nanoparticle hybrids. Importantly, the same nanoparticles adsorbed onto fibrils surface show improved catalytic efficiency compared to the same unattached particles, pointing at the important role played by the amyloid fibril templates. Then, filter membranes are prepared from the metal nanoparticle-decorated amyloid fibrils by vacuum filtration. The resulting membranes serve as efficient flow catalysis active materials, with a complete catalytic conversion achieved within a single flow passage of a feeding solution through the membrane.

  10. Complement activation by the amyloid proteins A beta peptide and beta 2-microglobulin

    DEFF Research Database (Denmark)

    Nybo, Mads; Nielsen, E H; Svehag, S E

    1999-01-01

    Complement activation (CA) has been reported to play a role in the pathogenesis of Alzheimer's disease (AD). To investigate whether CA may contribute to amyloidogenesis in general, the CA potential of different amyloid fibril proteins was tested. CA induced by A beta preparations containing soluble...... protein, protofilaments and some fibrils or only fibrils in a solid phase system (ELISA) was modest with a slow kinetics compared to the positive delta IgG control. Soluble A beta induced no detectable CA in a liquid phase system (complement consumption assay) while fibrillar A beta caused CA at 200 mg....../ml and higher concentrations. Soluble beta 2-microglobulin (beta 2M) purified from peritoneal dialysates was found to be as potent a complement activator as A beta in both solid and liquid phase systems while beta 2M purified from urine exhibited lower activity, a difference which may be explained...

  11. Native human serum amyloid P component is a single pentamer

    DEFF Research Database (Denmark)

    Sørensen, Inge Juul; Andersen, Ove; Nielsen, EH;

    1995-01-01

    Serum amyloid P component (SAP) and C-reactive protein (CRP) are members of the pentraxin protein family. SAP is the precursor protein to amyloid P component present in all forms of amyloidosis. The prevailing notion is that SAP in circulation has the form of a double pentameric molecule (decamer...... by rocket immunoelectrophoresis and electron microscopy. Thus, electron micrographs of purified SAP showed a predominance of decamers. However, the decamer form of SAP reversed to single pentamers when purified SAP was incorporated into SAP-depleted serum....

  12. Paradoxical Condensation of Copper with Elevated β-Amyloid in Lipid Rafts under Cellular Copper Deficiency Conditions: IMPLICATIONS FOR ALZHEIMER DISEASE*

    OpenAIRE

    Hung, Ya Hui; Robb, Elysia L.; Volitakis, Irene; Ho, Michael; Evin, Genevieve; Li, Qiao-Xin; Janetta G Culvenor; Masters, Colin L.; Cherny, Robert A.; Bush, Ashley I.

    2009-01-01

    Redox-active copper is implicated in the pathogenesis of Alzheimer disease (AD), β-amyloid peptide (Aβ) aggregation, and amyloid formation. Aβ·copper complexes have been identified in AD and catalytically oxidize cholesterol and lipid to generate H2O2 and lipid peroxides. The site and mechanism of this abnormality is not known. Growing evidence suggests that amyloidogenic processing of the β-amyloid precursor protein (APP) occurs in lipid rafts, membrane microdomains enriched in cholesterol. ...

  13. Amyloid protein-mediated differential DNA methylation status regulates gene expression in Alzheimer's disease model cell line

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Hye Youn; Choi, Eun Nam [Department of Biochemistry, School of Medicine, Ewha Womans University, 911-1 Mok-6-dong, Yangcheon-ku, Seoul 158-710 (Korea, Republic of); Ahn Jo, Sangmee [Department of Pharmacy, College of Pharmacy, Dankook University, San 29 Anseo-dong, Dongnam-gu, Cheonan-si, Chungnam 330-714 (Korea, Republic of); Oh, Seikwan [Department of Neuroscience and TIDRC, School of Medicine, Ewha Womans University, 911-1 Mok-6-dong, Yangcheon-ku, Seoul 158-710 (Korea, Republic of); Ahn, Jung-Hyuck, E-mail: ahnj@ewha.ac.kr [Department of Biochemistry, School of Medicine, Ewha Womans University, 911-1 Mok-6-dong, Yangcheon-ku, Seoul 158-710 (Korea, Republic of)

    2011-11-04

    Highlights: Black-Right-Pointing-Pointer Genome-wide DNA methylation pattern in Alzheimer's disease model cell line. Black-Right-Pointing-Pointer Integrated analysis of CpG methylation and mRNA expression profiles. Black-Right-Pointing-Pointer Identify three Swedish mutant target genes; CTIF, NXT2 and DDR2 gene. Black-Right-Pointing-Pointer The effect of Swedish mutation on alteration of DNA methylation and gene expression. -- Abstract: The Swedish mutation of amyloid precursor protein (APP-sw) has been reported to dramatically increase beta amyloid production through aberrant cleavage at the beta secretase site, causing early-onset Alzheimer's disease (AD). DNA methylation has been reported to be associated with AD pathogenesis, but the underlying molecular mechanism of APP-sw-mediated epigenetic alterations in AD pathogenesis remains largely unknown. We analyzed genome-wide interplay between promoter CpG DNA methylation and gene expression in an APP-sw-expressing AD model cell line. To identify genes whose expression was regulated by DNA methylation status, we performed integrated analysis of CpG methylation and mRNA expression profiles, and identified three target genes of the APP-sw mutant; hypomethylated CTIF (CBP80/CBP20-dependent translation initiation factor) and NXT2 (nuclear exporting factor 2), and hypermethylated DDR2 (discoidin domain receptor 2). Treatment with the demethylating agent 5-aza-2 Prime -deoxycytidine restored mRNA expression of these three genes, implying methylation-dependent transcriptional regulation. The profound alteration in the methylation status was detected at the -435, -295, and -271 CpG sites of CTIF, and at the -505 to -341 region in the promoter of DDR2. In the promoter region of NXT2, only one CpG site located at -432 was differentially unmethylated in APP-sw cells. Thus, we demonstrated the effect of the APP-sw mutation on alteration of DNA methylation and subsequent gene expression. This epigenetic regulatory

  14. Tissue transglutaminase colocalizes with extracellular matrix proteins in cerebral amyloid angiopathy.

    Science.gov (United States)

    de Jager, Mieke; van der Wildt, Berend; Schul, Emma; Bol, John G J M; van Duinen, Sjoerd G; Drukarch, Benjamin; Wilhelmus, Micha M M

    2013-04-01

    Cerebral amyloid angiopathy (CAA) is a key histopathological hallmark of Alzheimer's disease (AD) and hereditary cerebral hemorrhage with amyloidosis of the Dutch type (HCHWA-D). CAA is characterized by amyloid-beta (Aβ) depositions and remodeling of the extracellular matrix (ECM) in brain vessels and plays an important role in the development and progression of both AD and HCHWA-D. Tissue transglutaminase (tTG) modulates the ECM by molecular cross-linking of ECM proteins. Here, we investigated the distribution pattern, cellular source, and activity of tTG in CAA in control, AD, and HCHWA-D cases. We observed increased tTG immunoreactivity and colocalization with Aβ in the vessel wall in early stage CAA, whereas in later CAA stages, tTG and its cross-links were present in halos enclosing the Aβ deposition. In CAA, tTG and its cross-links at the abluminal side of the vessel were demonstrated to be either of astrocytic origin in parenchymal vessels, of fibroblastic origin in leptomeningeal vessels, and of endothelial origin at the luminal side of the deposited Aβ. Furthermore, the ECM proteins fibronectin and laminin colocalized with the tTG-positive halos surrounding the deposited Aβ in CAA. However, we observed that in situ tTG activity was present throughout the vessel wall in late stage CAA. Together, our data suggest that tTG and its activity might play a differential role in the development and progression of CAA, possibly evolving from direct modulation of Aβ aggregation to cross-linking of ECM proteins resulting in ECM restructuring.

  15. The β-amyloid protein induces S100β expression in rat hippocampus through a mechanism that involves IL-1

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective To explore the effect of β-amyloid protein (Aβ) on S100β expression in rat hippocampus and its mechanisms. Methods At 7 days after bilateral stereotaxis injection of different dose of fibrillar Aβ 25-35 and interluekin-1 receptor antagonist (IL-1ra) into the rat CA1 region, the learning and memory abilities of rats were tested with passive avoidance task. Amyloid deposition was detected by using Congo red staining technique. Nissl staining and immunohistochemical techniques were used to analyze th...

  16. Chronic administration of R-flurbiprofen attenuates learning impairments in transgenic amyloid precursor protein mice

    Directory of Open Access Journals (Sweden)

    Koo Edward H

    2007-07-01

    Full Text Available Abstract Background Long-term use of non-steroidal anti-inflammatory drugs (NSAIDs is associated with a reduced incidence of Alzheimer's disease (AD. We and others have shown that certain NSAIDs reduce secretion of Aβ42 in cell culture and animal models, and that the effect of NSAIDs on Aβ42 is independent of the inhibition of cyclooxygenase by these compounds. Since Aβ42 is hypothesized to be the initiating pathologic molecule in AD, the ability of these compounds to lower Aβ42 selectively may be associated with their protective effect. We have previously identified R-flurbiprofen (tarenflurbil as a selective Aβ42 lowering agent with greatly reduced cyclooxygenase activity that shows promise for testing this hypothesis. In this study we report the effect of chronic R-flurbiprofen treatment on cognition and Aβ loads in Tg2576 APP mice. Results A four-month preventative treatment regimen with R-flurbiprofen (10 mg/kg/day was administered to young Tg2576 mice prior to robust plaque or Aβ pathology. This treatment regimen improved spatial learning as assessed by the Morris water maze, indicated by an increased spatial bias during the third probe trial and an increased utilization of a place strategy to solve the water maze. These results are consistent with an improvement in hippocampal- and medial temporal lobe-dependent memory function. A modest, though not statistically significant, reduction in formic acid-soluble levels of Aβ was also observed. To determine if R-flurbiprofen could reverse cognitive deficits in Tg2576 mice where plaque pathology was already robust, a two-week therapeutic treatment was given to older Tg2576 mice with the same dose of R-flurbiprofen. This approach resulted in a significant decrease in Aβ plaque burden but no significant improvement in spatial learning. Conclusion We have found that chronic administration of R-flurbiprofen is able to attenuate spatial learning deficits if given prior to plaque deposition in Tg2576 mice. Given its ability to selectively target Aβ42 production and improve cognitive impairments in transgenic APP mice, as well as promising data from a phase 2 human clinical trial, future studies are needed to investigate the utility of R-flurbiprofen as an AD therapeutic and its possible mechanisms of action.

  17. The amyloid precursor protein controls adult hippocampal neurogenesis through GABAergic interneurons.

    Science.gov (United States)

    Wang, Baiping; Wang, Zilai; Sun, Lu; Yang, Li; Li, Hongmei; Cole, Allysa L; Rodriguez-Rivera, Jennifer; Lu, Hui-Chen; Zheng, Hui

    2014-10-01

    Impaired neurogenesis in the adult hippocampus has been implicated in AD pathogenesis. Here we reveal that the APP plays an important role in the neural progenitor proliferation and newborn neuron maturation in the mouse dentate gyrus. APP controls adult neurogenesis through a non cell-autonomous mechanism by GABAergic neurons, as selective deletion of GABAergic, but not glutamatergic, APP disrupts adult hippocampal neurogenesis. APP, highly expressed in the majority of GABAergic neurons in the dentate gyrus, enhances the inhibitory tone to granule cells. By regulating both tonic and phasic GABAergic inputs to dentate granule cells, APP maintains excitatory-inhibitory balance and preserves cognitive functions. Our studies uncover an indispensable role of APP in the GABAergic system for controlling adult hippocampal neurogenesis, and our findings indicate that APP dysfunction may contribute to impaired neurogenesis and cognitive decline associated with AD.

  18. Chronic administration of R-flurbiprofen attenuates learning impairments in transgenic amyloid precursor protein mice

    Science.gov (United States)

    Kukar, Thomas; Prescott, Sonya; Eriksen, Jason L; Holloway, Vallie; Murphy, M Paul; Koo, Edward H; Golde, Todd E; Nicolle, Michelle M

    2007-01-01

    Background Long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) is associated with a reduced incidence of Alzheimer's disease (AD). We and others have shown that certain NSAIDs reduce secretion of Aβ42 in cell culture and animal models, and that the effect of NSAIDs on Aβ42 is independent of the inhibition of cyclooxygenase by these compounds. Since Aβ42 is hypothesized to be the initiating pathologic molecule in AD, the ability of these compounds to lower Aβ42 selectively may be associated with their protective effect. We have previously identified R-flurbiprofen (tarenflurbil) as a selective Aβ42 lowering agent with greatly reduced cyclooxygenase activity that shows promise for testing this hypothesis. In this study we report the effect of chronic R-flurbiprofen treatment on cognition and Aβ loads in Tg2576 APP mice. Results A four-month preventative treatment regimen with R-flurbiprofen (10 mg/kg/day) was administered to young Tg2576 mice prior to robust plaque or Aβ pathology. This treatment regimen improved spatial learning as assessed by the Morris water maze, indicated by an increased spatial bias during the third probe trial and an increased utilization of a place strategy to solve the water maze. These results are consistent with an improvement in hippocampal- and medial temporal lobe-dependent memory function. A modest, though not statistically significant, reduction in formic acid-soluble levels of Aβ was also observed. To determine if R-flurbiprofen could reverse cognitive deficits in Tg2576 mice where plaque pathology was already robust, a two-week therapeutic treatment was given to older Tg2576 mice with the same dose of R-flurbiprofen. This approach resulted in a significant decrease in Aβ plaque burden but no significant improvement in spatial learning. Conclusion We have found that chronic administration of R-flurbiprofen is able to attenuate spatial learning deficits if given prior to plaque deposition in Tg2576 mice. Given its ability to selectively target Aβ42 production and improve cognitive impairments in transgenic APP mice, as well as promising data from a phase 2 human clinical trial, future studies are needed to investigate the utility of R-flurbiprofen as an AD therapeutic and its possible mechanisms of action. PMID:17650315

  19. Activation of human microglia by fibrillar prion protein-related peptides is enhanced by amyloid-associated factors SAP and C1q

    NARCIS (Netherlands)

    Veerhuis, R.; Boshuizen, R.S.; Morbin, M.; Mazzoleni, G.; Hoozemans, J.J.; Langedijk, J.P.; Tagliavini, F.; Langeveld, J.P.M.; Eikelenboom, P.

    2005-01-01

    Complement activation products C1q and C3d, serum amyloid P component (SAP) and activated glial cells accumulate in amyloid deposits of conformationally changed prion protein (PrPSc) in Creutzfeldt¿Jakob disease, Gerstmann¿Sträussler¿Scheinker disease and scrapie-infected mouse brain. Biological pro

  20. Amyloid-β peptides and tau protein as biomarkers in cerebrospinal and interstitial fluid following traumatic brain injury: A review of experimental and clinical studies

    Directory of Open Access Journals (Sweden)

    Parmenion P. Tsitsopoulos

    2013-06-01

    Full Text Available Traumatic brain injury (TBI survivors frequently suffer from life-long deficits in cognitive functions and a reduced quality of life. Axonal injury, observed in most severe TBI patients, results in accumulation of amyloid precursor protein (APP. Post-injury enzymatic cleavage of APP can generate amyloid-β (Aβ peptides, a hallmark finding in Alzheimer’s disease (AD. At autopsy, brains of AD and a subset of TBI victims display some similarities including accumulation of Aβ peptides and neurofibrillary tangles of hyperphosphorylated tau proteins. Most epidemiological evidence suggests a link between TBI and AD, implying that TBI has neurodegenerative sequelae. Aβ peptides and tau may be used as biomarkers in interstitial fluid (ISF using cerebral microdialysis and/or cerebrospinal fluid (CSF following clinical TBI. In the present review, the available clinical and experimental literature on Aβ peptides and tau as potential biomarkers following TBI is comprehensively analyzed. Elevated CSF and ISF tau protein levels have been observed following severe TBI and suggested to correlate with clinical outcome. Although Aβ peptides are produced by normal neuronal metabolism, high levels of long and/or fibrillary Aβ peptides may be neurotoxic. Increased CSF and/or ISF Aβ levels post-injury may be related to neuronal activity and/or the presence of axonal injury. The heterogeneity of animal models, clinical cohorts, analytical techniques and the complexity of TBI in available studies make the clinical value of tau and Aβ as biomarkers uncertain at present. Additionally, the link between early post-injury changes in tau and Aβ peptides and the future risk of developing AD remains unclear. Future studies using e.g. rapid biomarker sampling combined with enhanced analytical techniques and/or novel pharmacological tools could provide additional information on the importance of Aβ peptides and tau protein in both the acute pathophysiology and long

  1. Evidence of a Novel Mechanism for Partial γ-Secretase Inhibition Induced Paradoxical Increase in Secreted Amyloid β Protein

    Science.gov (United States)

    Baranello, Robert; Pacheco-Quinto, Javier; Crosson, Craig; Ablonczy, Zsolt; Eckman, Elizabeth; Eckman, Christopher B.; Ramakrishnan, Viswanathan; Greig, Nigel H.; Pappolla, Miguel A.; Sambamurti, Kumar

    2014-01-01

    BACE1 (β-secretase) and α-secretase cleave the Alzheimer's amyloid β protein (Aβ) precursor (APP) to C-terminal fragments of 99 aa (CTFβ) and 83 aa (CTFα), respectively, which are further cleaved by γ-secretase to eventually secrete Aβ and Aα (a.k.a. P3) that terminate predominantly at residues 40 and 42. A number of γ-secretase inhibitors (GSIs), such as N-[N-(3,5-Difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester (DAPT), have been developed with the goal of reducing Aβ to treat Alzheimer's disease (AD). Although most studies show that DAPT inhibits Aβ in a dose-dependent manner several studies have also detected a biphasic effect with an unexpected increase at low doses of DAPT in cell cultures, animal models and clinical trials. In this article, we confirm the increase in Aβ40 and Aβ42 in SH-SY5Y human neuroblastoma cells treated with low doses of DAPT and identify one of the mechanisms for this paradox. We studied the pathway by first demonstrating that stimulation of Aβ, a product of γ-secretase, was accompanied by a parallel increase of its substrate CTFβ, thereby demonstrating that the inhibitor was not anomalously stimulating enzyme activity at low levels. Secondly, we have demonstrated that inhibition of an Aβ degrading activity, endothelin converting enzyme (ECE), yielded more Aβ, but abolished the DAPT-induced stimulation. Finally, we have demonstrated that Aα, which is generated in the secretory pathway before endocytosis, is not subject to the DAPT-mediated stimulation. We therefore conclude that impairment of γ-secretase can paradoxically increase Aβ by transiently skirting Aβ degradation in the endosome. This study adds to the growing body of literature suggesting that preserving γ-secretase activity, rather than inhibiting it, is important for prevention of neurodegeneration. PMID:24658363

  2. Evidence of a novel mechanism for partial γ-secretase inhibition induced paradoxical increase in secreted amyloid β protein.

    Directory of Open Access Journals (Sweden)

    Eliza Barnwell

    Full Text Available BACE1 (β-secretase and α-secretase cleave the Alzheimer's amyloid β protein (Aβ precursor (APP to C-terminal fragments of 99 aa (CTFβ and 83 aa (CTFα, respectively, which are further cleaved by γ-secretase to eventually secrete Aβ and Aα (a.k.a. P3 that terminate predominantly at residues 40 and 42. A number of γ-secretase inhibitors (GSIs, such as N-[N-(3,5-Difluorophenacetyl-L-alanyl]-S-phenylglycine t-butyl ester (DAPT, have been developed with the goal of reducing Aβ to treat Alzheimer's disease (AD. Although most studies show that DAPT inhibits Aβ in a dose-dependent manner several studies have also detected a biphasic effect with an unexpected increase at low doses of DAPT in cell cultures, animal models and clinical trials. In this article, we confirm the increase in Aβ40 and Aβ42 in SH-SY5Y human neuroblastoma cells treated with low doses of DAPT and identify one of the mechanisms for this paradox. We studied the pathway by first demonstrating that stimulation of Aβ, a product of γ-secretase, was accompanied by a parallel increase of its substrate CTFβ, thereby demonstrating that the inhibitor was not anomalously stimulating enzyme activity at low levels. Secondly, we have demonstrated that inhibition of an Aβ degrading activity, endothelin converting enzyme (ECE, yielded more Aβ, but abolished the DAPT-induced stimulation. Finally, we have demonstrated that Aα, which is generated in the secretory pathway before endocytosis, is not subject to the DAPT-mediated stimulation. We therefore conclude that impairment of γ-secretase can paradoxically increase Aβ by transiently skirting Aβ degradation in the endosome. This study adds to the growing body of literature suggesting that preserving γ-secretase activity, rather than inhibiting it, is important for prevention of neurodegeneration.

  3. Increased plasma amyloid beta protein 1-42 levels in Down syndrome.

    Science.gov (United States)

    Mehta, P D; Dalton, A J; Mehta, S P; Kim, K S; Sersen, E A; Wisniewski, H M

    1998-01-23

    Amyloid beta protein 1-40 (A beta40) and A beta42 levels were quantitated in plasma from 43 persons with Down syndrome (DS; 26-68 years of age), 43 age-matched normal controls, and 19 non-DS mentally retarded (MR) persons (26-91 years of age) by using a sandwich enzyme linked immunosorbent assay. A beta40 levels were higher in DS and MR than controls, but were similar between DS and MR groups. A beta42 levels were higher in DS than controls or MR persons. The ratios of A beta42/A beta40 were higher in DS than controls or MR persons. The findings are consistent with those seen in DS brains.

  4. Alzheimer's disease amyloid peptides interact with DNA, as proved by surface plasmon resonance.

    Science.gov (United States)

    Barrantes, Alejandro; Camero, Sergio; Garcia-Lucas, Angel; Navarro, Pedro J; Benitez, María J; Jiménez, Juan S

    2012-10-01

    According to the amyloid hypothesis, abnormal processing of the β-amyloid precursor protein in Alzheimer's disease patients increases the production of β-amyloid toxic peptides, which, after forming highly aggregated fibrillar structures, lead to extracellular plaques formation, neuronal loss and dementia. However, a great deal of evidence has point to intracellular small oligomers of amyloid peptides, probably transient intermediates in the process of fibrillar structures formation, as the most toxic species. In order to study the amyloid-DNA interaction, we have selected here three different forms of the amyloid peptide: Aβ1-40, Aβ25-35 and a scrambled form of Aβ25-35. Surface Plasmon Resonance was used together with UV-visible spectroscopy, Electrophoresis and Electronic Microscopy to carry out this study. Our results prove that, similarly to the full length Aβ1-42, all conformations of toxic amyloid peptides, Aβ1-40 and Aβ25-35, may bind DNA. In contrast, the scrambled form of Aβ25-35, a non-aggregating and nontoxic form of this peptide, could not bind DNA. We conclude that although the amyloid-DNA interaction is closely related to the amyloid aggregation proneness, this cannot be the only factor which determines the interaction, since small oligomers of amyloid peptides may also bind DNA if their predominant negatively charged amino acid residues are previously neutralized.

  5. Mechanism of neuronal versus endothelial cell uptake of Alzheimer's disease amyloid beta protein.

    Directory of Open Access Journals (Sweden)

    Karunya K Kandimalla

    Full Text Available Alzheimer's disease (AD is characterized by significant neurodegeneration in the cortex and hippocampus; intraneuronal tangles of hyperphosphorylated tau protein; and accumulation of beta-amyloid (Abeta proteins 40 and 42 in the brain parenchyma as well as in the cerebral vasculature. The current understanding that AD is initiated by the neuronal accumulation of Abeta proteins due to their inefficient clearance at the blood-brain-barrier (BBB, places the neurovascular unit at the epicenter of AD pathophysiology. The objective of this study is to investigate cellular mechanisms mediating the internalization of Abeta proteins in the principle constituents of the neurovascular unit, neurons and BBB endothelial cells. Laser confocal micrographs of wild type (WT mouse brain slices treated with fluorescein labeled Abeta40 (F-Abeta40 demonstrated selective accumulation of the protein in a subpopulation of cortical and hippocampal neurons via nonsaturable, energy independent, and nonendocytotic pathways. This groundbreaking finding, which challenges the conventional belief that Abeta proteins are internalized by neurons via receptor mediated endocytosis, was verified in differentiated PC12 cells and rat primary hippocampal (RPH neurons through laser confocal microscopy and flow cytometry studies. Microscopy studies have demonstrated that a significant proportion of F-Abeta40 or F-Abeta42 internalized by differentiated PC12 cells or RPH neurons is located outside of the endosomal or lysosomal compartments, which may accumulate without degradation. In contrast, BBME cells exhibit energy dependent uptake of F-Abeta40, and accumulate the protein in acidic cell organelle, indicative of endocytotic uptake. Such a phenomenal difference in the internalization of Abeta40 between neurons and BBB endothelial cells may provide essential clues to understanding how various cells can differentially regulate Abeta proteins and help explain the vulnerability of cortical

  6. Binding of an oxindole alkaloid from Uncaria tomentosa to amyloid protein (Abeta1-40).

    Science.gov (United States)

    Frackowiak, Teresa; Baczek, Tomasz; Roman, Kaliszana; Zbikowska, Beata; Gleńsk, Michał; Fecka, Izabela; Cisowski, Wojciech

    2006-01-01

    The primary aim of this work was to determine the interactions of an oxindole alkaloid (mitraphylline) isolated from Uncaria tomentosa with beta-amyloid 1-40 (Abeta1-40 protein) applying the capillary electrophoresis (CE) method. Specifically the Hummel-Dreyer method and Scatchard analysis were performed to study the binding of oxindole alkaloids with Abeta1-40 protein. Prior to these studies extraction of the alkaloid of interest was carried out. Identification of the isolated alkaloid was performed by the use of thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) combined with electrospray ionization mass spectrometry (ESI-MS). The proposed approach was proved to be an efficient and accurate method for specific compound isolation and identification purposes. Moreover, analytical information from the CE approach can be considered as the valuable tool for binding constant determination. The binding constant of mitraphylline with Abeta1-40 protein determined by the Hummel-Dreyer method and Scatchard analysis equals K = 9.95 x 10(5) M(-1). The results obtained showed the significant binding of the tested compound with Abeta1-40 protein. These results are discussed and interpreted in the view of developing a strategy for identification of novel compounds of great importance in Alzheimer disease therapy.

  7. MD-simulations of Beta-Amyloid Protein Insertion Efficiency and Kinetics into Neuronal Membrane Mimics

    Science.gov (United States)

    Qiu, Liming; Buie, Creighton; Vaughn, Mark; Cheng, Kwan

    2011-03-01

    Early interaction events of beta-amyloid (A β) peptides with the neuronal membranes play a key role in the pathogenesis of Alzheimer's disease. We have used all-atom MD simulations to study the protein insertion efficiency and kinetics of monomeric A β40 and A β42 into phosphatidylcholine lipid bilayers (PC) with and without 40 mole% cholesterol (CHOL) that mimic the cholesterol-enriched and depleted lipid nanodomains of the neuronal plasma membranes. Independent replicates of 200-ns simulations of each protein pre-inserted in the upper lipid layer were generated. In PC bilayers, only 25% of A β40 and 50% of A β42 in the replicates showed complete insertion into the lower lipid layer, whereas the percentages increased to 50% and 100%, respectively, in PC/CHOL bilayers, providing evidence that cholesterol improves the protein insertion efficiency into the bilayers. The rate of protein insertion was proportional to the hydrophobic, transmembrane helix length of the inserted peptide and depended on the cholesterol content. We propose that the lysine snorkeling and C-terminus anchoring of A β to the PC headgroups at the upper and lower lipid/water interfaces represent the dual-transmembrane stabilization mechanisms of A β in the neuronal membrane domains.

  8. Control the aggregation of model amyloid insulin protein under ac-electric fields

    Science.gov (United States)

    Zheng, Zhongli; Jing, Benxin; Zhu, Y. Elaine

    2013-03-01

    In vitro experiments have been widely used to characterize the misfolding/unfolding pathway characteristic of amylodogenic proteins. Conversion from natively folded amyloidogenic proteins to oligomers via nucleation is the accepted path to fibril formation upon heating over a certain lag time period. In an alternative engineering approach to manipulate and control protein aggregation, we have investigated the aggregation kinetics of insulin, a well-established amyloid model protein, under applied ac-electric fields of varied ac-frequency and voltage at room temperature. Using fluorescence correlation spectroscopy and fluorescence imaging, we have observed that the insulin aggregation can occur at much shortened lag time under applied ac-electric fields, when a critical ac-voltage is exceeded. The strong dependence of lag time on ac-frequency over a narrow range of 500 Hz-5 kHz indicates the effect of ac-electroosmosis on the diffusion controlled process of insulin nucleation. Yet, no difference of conformational structure is detected with insulin under applied ac-fields, suggesting the equivalence of ac-polarization to the conventional thermal activation process for insulin aggregation.

  9. Processing Pisum sativum seed storage protein precursors in vitro

    Institute of Scientific and Technical Information of China (English)

    YANGLIJUN; CDOMONEY; 等

    1990-01-01

    The profile of polypeptides separated by SDS-PAGE from seed of major crop species such as pea(Pisum sativum) is complex,resulting from cleavage (processing) of precursors expressed from multiple copies of genes encoding vicilin and legumin,the major storage globulins.Translation in vitro of mRNAs hybridselected from mid-maturation pea seed RNAs by defined vicilin and legumin cDNA clones provided precursor molecules that were cleaved in vitro by a cell-free protease extract obtained from similar stage seed;the derived polypeptides were of comparable sizes to those observed in vivo.The feasibility of transcribing mRNA in vitro from a cDNA clone and cleavage in vitro of the derived translation products was established for a legumin clone,providing a method for determining polypeptide products of an expressed sequence.This approach will also be useful for characterising cleavage site requirements since modifications an readily be introduced at the DNA level.

  10. Precision biopolymers from protein precursors for biomedical applications.

    Science.gov (United States)

    Kuan, Seah Ling; Wu, Yuzhou; Weil, Tanja

    2013-03-12

    The synthesis of biohybrid materials with tailored functional properties represents a topic of emerging interest. Combining proteins as natural, macromolecular building blocks, and synthetic polymers opens access to giant brush-like biopolymers of high structural definition. The properties of these precision polypeptide copolymers can be tailored through various chemical modifications along their polypeptide backbone, which expands the repertoire of known protein-based materials to address biomedical applications. In this article, the synthetic strategies for the design of precision biopolymers from proteins through amino acid specific conjugation reagents are highlighted and the different functionalization strategies, their characterization, and applications are discussed.

  11. Differential gene expression in human brain pericytes induced by amyloid-beta protein.

    NARCIS (Netherlands)

    Rensink, A.A.M.; Otte-Holler, I.; Donkelaar, H.J. ten; Waal, R.M.W. de; Kremer, H.P.H.; Verbeek, M.M.

    2004-01-01

    Cerebral amyloid angiopathy is one of the characteristics of Alzheimer's disease (AD) and this accumulation of fibrillar amyloid-beta (Alphabeta) in the vascular wall is accompanied by marked vascular damage. In vitro, Abeta1-40 carrying the 'Dutch' mutation (DAbeta1-40) induces degeneration of cult

  12. Fatal transmissible amyloid encephalopathy: a new type of prion disease associated with lack of prion protein membrane anchoring.

    Directory of Open Access Journals (Sweden)

    Bruce Chesebro

    2010-03-01

    Full Text Available Prion diseases are fatal neurodegenerative diseases of humans and animals characterized by gray matter spongiosis and accumulation of aggregated, misfolded, protease-resistant prion protein (PrPres. PrPres can be deposited in brain in an amyloid-form and/or non-amyloid form, and is derived from host-encoded protease-sensitive PrP (PrPsen, a protein normally anchored to the plasma membrane by glycosylphosphatidylinositol (GPI. Previously, using heterozygous transgenic mice expressing only anchorless PrP, we found that PrP anchoring to the cell membrane was required for typical clinical scrapie. However, in the present experiments, using homozygous transgenic mice expressing two-fold more anchorless PrP, scrapie infection induced a new fatal disease with unique clinical signs and altered neuropathology, compared to non-transgenic mice expressing only anchored PrP. Brain tissue of transgenic mice had high amounts of infectivity, and histopathology showed dense amyloid PrPres plaque deposits without gray matter spongiosis. In contrast, infected non-transgenic mice had diffuse non-amyloid PrPres deposits with significant gray matter spongiosis. Brain graft studies suggested that anchored PrPsen expression was required for gray matter spongiosis during prion infection. Furthermore, electron and light microscopic studies in infected transgenic mice demonstrated several pathogenic processes not seen in typical prion disease, including cerebral amyloid angiopathy and ultrastructural alterations in perivascular neuropil. These findings were similar to certain human familial prion diseases as well as to non-prion human neurodegenerative diseases, such as Alzheimer's disease.

  13. Discovery and identification of Serum Amyloid A protein elevated in lung cancer serum

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Two hundred and eighteen serum samples from 175 lung cancer patients and 43 healthy individuals were analyzed by using Surface Enhaced Laser Desorption/Ionization Time of Flight Mass Spectrome- try (SELDI-TOF-MS). The data analyzed by both Biomarker Wizard? and Biomarker Patterns? software showed that a protein peak with the molecular weight of 11.6 kDa significantly increased in lung cancer. Meanwhile,the level of this biomarker was progressively increased with the clinical stages of lung cancer. The candidate biomarker was then obtained from tricine one-dimensional sodium dodecyl sul- fate-polyacrylamide gel electrophoresis by matching the molecular weight with peaks on WCX2 chips and was identified as Serum Amyloid A protein (SAA) by MALDI/MS-MS and database searching. It was further validated in the same serum samples by immunoprecipitation with commercial SAA antibody. To confirm the SAA differential expression in lung cancer patients, the same set of serum samples was measured by ELISA assay. The result showed that at the cutoff point 0.446(OD value)on the Receiver Operating Characteristic (ROC) curve, SAA could better discriminate lung cancer from healthy indi- viduals with sensitivity of 84.1% and specificity of 80%. These findings demonstrated that SAA could be characterized as a biomarker related to pathological stages of lung cancer.

  14. Developmental regulation of expression of C-reactive protein and serum amyloid A in Syrian hamsters.

    Science.gov (United States)

    Dowton, S B; Waggoner, D J; Mandl, K D

    1991-11-01

    The fetal and maternal concentration of various plasma proteins alters during pregnancy. Cells in the livers of fetal hamsters accumulate serum amyloid A (SAA) and C-reactive protein (CRP) mRNA, major acute phase reactants, when lipopolysaccharide is administered to the fetal circulation. No fetal SAA or CRP mRNA response is seen when the mother is stimulated at a remote site by endotoxin or a nonspecific inflammatory agent. In addition, cells of the fetal hamster liver do not respond by accumulating SAA mRNA when exposed to the specific cytokines, tumor necrosis factor, IL-1, and IL-6. CRP mRNA levels increased in fetal livers after administration of tumor necrosis factor and IL-1. These data suggest that cells contained in the fetal liver can respond during an acute phase reaction but that the capacity of some acute phase reactant genes to respond to cytokines may be developmentally regulated. Studies of immature hamsters after birth show that the responses of CRP and SAA genes to lipopolysaccharide, tumor necrosis factor, IL-1, and IL-6 are reduced when compared with induction of mRNA accumulation for these acute phase reactants in adult animals.

  15. Transient expression of a mitochondrial precursor protein - A new approach to study mitochondrial protein import in cells of higher eukaryotes

    NARCIS (Netherlands)

    Huckriede, A; Heikema, A; Wilschut, J; Agsteribbe, E

    1996-01-01

    In order to study mitochondrial protein import in the context of whole cell metabolism, we have used the transfection technique based on Semliki Forest virus (SFV) to express a mitochondrial precursor protein within BHK21 cells and human fibroblasts. Recombinant SFV particles mediate a highly effici

  16. Diversity, biogenesis and function of microbial amyloids

    OpenAIRE

    2011-01-01

    Amyloid is a distinct β-sheet-rich fold that many proteins can acquire. Frequently associated with neurodegenerative diseases in humans, including Alzheimer’s, Parkinson’s and Huntington’s, amyloids are traditionally considered the product of protein misfolding. However, the amyloid fold is now recognized as a ubiquitous part of normal cellular biology. ‘Functional’ amyloids have been identified in nearly all facets of cellular life, with microbial functional amyloids leading the way. Unlike ...

  17. Chronic pre-treatment with memantine prevents amyloid-beta protein-mediated long-term potentiation disruption

    Institute of Scientific and Technical Information of China (English)

    Fushun Li; Xiaowei Chen; Feiming Wang; Shujun Xu; Lan Chang; Roger Anwyl; Qinwen Wang

    2013-01-01

    Previous studies indicate that memantine, a low-affinity N-methyl-D-aspartate receptor antagonist, exerted acute protective effects against amyloidprotein-induced neurotoxicity. In the present study, the chronic effects and mechanisms of memantine were investigated further using electrophysiological methods. The results showed that 7-day intraperitoneal application of memantine, at doses of 5 mg/kg or 20 mg/kg, did not alter hippocampal long-term potentiation induction in rats, while 40 mg/kg memantine presented potent long-term potentiation inhibition. Then further in vitro studys were carried out in 5 mg/kg and 20 mg/kg memantine treated rats. We found that 20 mg/kg memantine attenuated the potent long-term potentiation inhibition caused by exposure to amyloidprotein in the dentate gyrus in vitro. These findings are the first to demonstrate the antagonizing effect of long-term systematic treatment of memantine against amyloidprotein triggered long-term potentiation inhibition to improve synaptic plasticity.

  18. The OPEP protein model: from single molecules, amyloid formation, crowding and hydrodynamics to DNA/RNA systems.

    Science.gov (United States)

    Sterpone, Fabio; Melchionna, Simone; Tuffery, Pierre; Pasquali, Samuela; Mousseau, Normand; Cragnolini, Tristan; Chebaro, Yassmine; St-Pierre, Jean-Francois; Kalimeri, Maria; Barducci, Alessandro; Laurin, Yoann; Tek, Alex; Baaden, Marc; Nguyen, Phuong Hoang; Derreumaux, Philippe

    2014-07-07

    The OPEP coarse-grained protein model has been applied to a wide range of applications since its first release 15 years ago. The model, which combines energetic and structural accuracy and chemical specificity, allows the study of single protein properties, DNA-RNA complexes, amyloid fibril formation and protein suspensions in a crowded environment. Here we first review the current state of the model and the most exciting applications using advanced conformational sampling methods. We then present the current limitations and a perspective on the ongoing developments.

  19. Purification and Refolding to Amyloid Fibrils of (His)6-tagged Recombinant Shadoo Protein Expressed as Inclusion Bodies in E. coli.

    Science.gov (United States)

    Li, Qiaojing; Richard, Charles-Adrien; Moudjou, Mohammed; Vidic, Jasmina

    2015-12-19

    The Escherichia coli expression system is a powerful tool for the production of recombinant eukaryotic proteins. We use it to produce Shadoo, a protein belonging to the prion family. A chromatographic method for the purification of (His)6-tagged recombinant Shadoo expressed as inclusion bodies is described. The inclusion bodies are solubilized in 8 M urea and bound to a Ni(2+)-charged column to perform ion affinity chromatography. Bound proteins are eluted by a gradient of imidazole. Fractions containing Shadoo protein are subjected to size exclusion chromatography to obtain a highly purified protein. In the final step purified Shadoo is desalted to remove salts, urea and imidazole. Recombinant Shadoo protein is an important reagent for biophysical and biochemical studies of protein conformation disorders occurring in prion diseases. Many reports demonstrated that prion neurodegenerative diseases originate from the deposition of stable, ordered amyloid fibrils. Sample protocols describing how to fibrillate Shadoo into amyloid fibrils at acidic and neutral/basic pHs are presented. The methods on how to produce and fibrillate Shadoo can facilitate research in laboratories working on prion diseases, since it allows for production of large amounts of protein in a rapid and low cost manner.

  20. Amyloid-β Activates Microglia and Regulates Protein Expression in a Manner Similar to Prions.

    Science.gov (United States)

    Tu, Jian; Chen, Baian; Yang, Lifeng; Qi, Kezong; Lu, Jing; Zhao, Deming

    2015-06-01

    Prions are the only convincingly demonstrated proteinaceous infectious particle, yet recent studies find that amyloid-β peptide (Aβ) aggregates are capable of self-propagation, which induces amyloidosis pathology in Alzheimer's disease (AD) model mice that is similar to the self-propagation phenomenon of prions in neurons. Gliosis is a common hallmark of AD and prion diseases, in which activated microglia accumulate around abnormal protein deposits. Analyses of the characteristics of activated microglia induced by Aβ in comparison with those induced by prions will provide new insight into the pathogenesis of AD. Therefore, we compared the characteristics of BV-2 cells (model microglia) activated by Aβ fibrillar peptides (Aβ1-42) and prions (PrP106-126). Aβ1-42 and PrP106-126, as well as the supernatants of the media collected from BV-2 cells cocultured with Aβ1-42 and PrP106-126, were potent activators of BV-2 microglial activity, but the chemotaxis index (CI) induced by Aβ1-42 was significantly higher than that induced by PrP106-126 at each concentration. Aβ1-42 and PrP106-126 increased the proliferation index (PI) and upregulated monocyte chemoattractant protein-1 (MCP-1) and transforming growth factor beta 1 (TGF-β1) expression after 12 h of exposure. Our results show that Aβ activates microglia and regulates microglial protein expression in a manner similar to prions and, thus, provide new insight into the pathogenesis of AD.

  1. Truncated prion protein PrP226* - A structural view on its role in amyloid disease.

    Science.gov (United States)

    Kovač, Valerija; Zupančič, Blaž; Ilc, Gregor; Plavec, Janez; Čurin Šerbec, Vladka

    2017-02-26

    In the brain of patients with transmissible spongiform encephalopathies, besides PrP(Sc) aggregates, deposition of truncated PrP molecules was described. Jansen et al. reported two clinical cases with deposition of C-terminally truncated PrP, one of them ending with Tyr226. We have previously described the discovery of monoclonal antibody V5B2 that selectively recognizes this version of the prion protein, which we called PrP226*. Using monoclonal antibody V5B2 we showed that accumulation of PrP226* is characteristic for most types of human and animal TSEs. Its distribution correlates to the distribution of PrP(Sc) aggregates. To gain insight into the structural basis of its presence and distribution in PrP aggregates, we have determined the NMR structure of recombinant PrP226*. The structure of the protein consists of a disordered N-terminal part (residues 90-125) and a structured C-terminal part (residues 126-226). The C-terminal segment consists of four α-helices and a short antiparallel β-sheet. Our model predicts a break in the C-terminal helix and reorganized hydrophobic interactions between helix α3 and β2-α2 loop due to the shorter C-terminus. The structural model gives information on the possible role of the protein in the development of amyloid disease and can serve as a foundation to develop tools for prevention and treatment of prion diseases.

  2. New Insights in the Amyloid-Beta Interaction with Mitochondria

    Directory of Open Access Journals (Sweden)

    Carlos Spuch

    2012-01-01

    Full Text Available Biochemical and morphological alterations of mitochondria may play an important role in the pathogenesis of Alzheimer’s disease (AD. Particularly, mitochondrial dysfunction is a hallmark of amyloid-beta-induced neuronal toxicity in Alzheimer’s disease. The recent emphasis on the intracellular biology of amyloid-beta and its precursor protein (APP has led researchers to consider the possibility that mitochondria-associated and mitochondrial amyloid-beta may directly cause neurotoxicity. Both proteins are known to localize to mitochondrial membranes, block the transport of nuclear-encoded mitochondrial proteins to mitochondria, interact with mitochondrial proteins, disrupt the electron transport chain, increase reactive oxygen species production, cause mitochondrial damage, and prevent neurons from functioning normally. In this paper, we will outline current knowledge of the intracellular localization of amyloid-beta. Moreover, we summarize evidence from AD postmortem brain as well as animal AD models showing that amyloid-beta triggers mitochondrial dysfunction through a number of pathways such as impairment of oxidative phosphorylation, elevation of reactive oxygen species production, alteration of mitochondrial dynamics, and interaction with mitochondrial proteins. Thus, this paper supports the Alzheimer cascade mitochondrial hypothesis such as the most important early events in this disease, and probably one of the future strategies on the therapy of this neurodegenerative disease.

  3. Parallel in-register intermolecular β-sheet architectures for prion-seeded prion protein (PrP) amyloids.

    Science.gov (United States)

    Groveman, Bradley R; Dolan, Michael A; Taubner, Lara M; Kraus, Allison; Wickner, Reed B; Caughey, Byron

    2014-08-29

    Structures of the infectious form of prion protein (e.g. PrP(Sc) or PrP-Scrapie) remain poorly defined. The prevalent structural models of PrP(Sc) retain most of the native α-helices of the normal, noninfectious prion protein, cellular prion protein (PrP(C)), but evidence is accumulating that these helices are absent in PrP(Sc) amyloid. Moreover, recombinant PrP(C) can form amyloid fibrils in vitro that have parallel in-register intermolecular β-sheet architectures in the domains originally occupied by helices 2 and 3. Here, we provide solid-state NMR evidence that the latter is also true of initially prion-seeded recombinant PrP amyloids formed in the absence of denaturants. These results, in the context of a primarily β-sheet structure, led us to build detailed models of PrP amyloid based on parallel in-register architectures, fibrillar shapes and dimensions, and other available experimentally derived conformational constraints. Molecular dynamics simulations of PrP(90-231) octameric segments suggested that such linear fibrils, which are consistent with many features of PrP(Sc) fibrils, can have stable parallel in-register β-sheet cores. These simulations revealed that the C-terminal residues ∼124-227 more readily adopt stable tightly packed structures than the N-terminal residues ∼90-123 in the absence of cofactors. Variations in the placement of turns and loops that link the β-sheets could give rise to distinct prion strains capable of faithful template-driven propagation. Moreover, our modeling suggests that single PrP monomers can comprise the entire cross-section of fibrils that have previously been assumed to be pairs of laterally associated protofilaments. Together, these insights provide a new basis for deciphering mammalian prion structures.

  4. Gene expression profile of amyloid beta protein-injected mouse model for Alzheimer disease

    Institute of Scientific and Technical Information of China (English)

    Ling-na KONG; Ping-ping ZUO; Liang MU; Yan-yong LIU; Nan YANG

    2005-01-01

    Aim: To investigate the gene expression profile changes in the cerebral cortex of mice injected icv with amyloid beta-protein (Aβ) fragment 25-35 using cDNA microarray. Methods: Balb/c mice were randomly divided into a control group and Aβ-treated group. The Morris water maze test was performed to detect the effect of Aβ-injection on the learning and memory of mice. Atlas Mouse 1.2 Expression Arrays containing 1176 genes were used to investigate the gene expression pattern of each group. Results: The gene expression profiles showed that 19 genes including TBX1, NF-κB, AP-1/c-Jun, cadherin, integrin, erb-B2, and FGFR1 were up-regulated after 2 weeks oficv administration of Aβ; while 12 genes were downregulated, including NGF, glucose phosphate isomerase 1, AT motif binding factor 1, Na+/K+-ATPase, and Akt. Conclusions: The results provide important leads for pursuing a more complete understanding of the molecular events of Aβ-injection into mice with Alzheimer disease.

  5. Alzheimer's associated β-amyloid protein inhibits influenza A virus and modulates viral interactions with phagocytes.

    Directory of Open Access Journals (Sweden)

    Mitchell R White

    Full Text Available Accumulation of β-Amyloid (βA is a key pathogenetic factor in Alzheimer's disease; however, the normal function of βA is unknown. Recent studies have shown that βA can inhibit growth of bacteria and fungi. In this paper we show that βA also inhibits replication of seasonal and pandemic strains of H3N2 and H1N1 influenza A virus (IAV in vitro. The 42 amino acid fragment of βA (βA42 had greater activity than the 40 amino acid fragment. Direct incubation of the virus with βA42 was needed to achieve optimal inhibition. Using quantitative PCR assays βA42 was shown to reduce viral uptake by epithelial cells after 45 minutes and to reduce supernatant virus at 24 hours post infection. βA42 caused aggregation of IAV particles as detected by light transmission assays and electron and confocal microscopy. βA42 did not stimulate neutrophil H2O2 production or extracellular trap formation on its own, but it increased both responses stimulated by IAV. In addition, βA42 increased uptake of IAV by neutrophils. βA42 reduced viral protein synthesis in monocytes and reduced IAV-induced interleukin-6 production by these cells. Hence, we demonstrate for the first time that βA has antiviral activity and modulates viral interactions with phagocytes.

  6. The Alzheimer's disease-associated amyloid beta-protein is an antimicrobial peptide.

    Directory of Open Access Journals (Sweden)

    Stephanie J Soscia

    Full Text Available BACKGROUND: The amyloid beta-protein (Abeta is believed to be the key mediator of Alzheimer's disease (AD pathology. Abeta is most often characterized as an incidental catabolic byproduct that lacks a normal physiological role. However, Abeta has been shown to be a specific ligand for a number of different receptors and other molecules, transported by complex trafficking pathways, modulated in response to a variety of environmental stressors, and able to induce pro-inflammatory activities. METHODOLOGY/PRINCIPAL FINDINGS: Here, we provide data supporting an in vivo function for Abeta as an antimicrobial peptide (AMP. Experiments used established in vitro assays to compare antimicrobial activities of Abeta and LL-37, an archetypical human AMP. Findings reveal that Abeta exerts antimicrobial activity against eight common and clinically relevant microorganisms with a potency equivalent to, and in some cases greater than, LL-37. Furthermore, we show that AD whole brain homogenates have significantly higher antimicrobial activity than aged matched non-AD samples and that AMP action correlates with tissue Abeta levels. Consistent with Abeta-mediated activity, the increased antimicrobial action was ablated by immunodepletion of AD brain homogenates with anti-Abeta antibodies. CONCLUSIONS/SIGNIFICANCE: Our findings suggest Abeta is a hitherto unrecognized AMP that may normally function in the innate immune system. This finding stands in stark contrast to current models of Abeta-mediated pathology and has important implications for ongoing and future AD treatment strategies.

  7. The effect of zinc on amyloid β-protein assembly and toxicity: A mechanistic investigation

    Science.gov (United States)

    Solomonov, Inna; Sagi, Irit

    2014-10-01

    Neurotoxic assemblies of amyloid β-protein (Aβ) are widely believed to be the cause for Alzheimer's disease (AD). Therefore, understanding the factors and mechanisms that control, modulate, and inhibit formation of these assemblies is crucial for the development of therapeutic intervention of AD. This information also can contribute significantly to our understanding of the mechanisms of other amyloidosis diseases, such as Parkinson's disease, Huntington's disease, type 2 diabetes, amyotrophic lateral sclerosis (Lou Gehrig's disease) and prion diseases (e.g. Mad Cow disease). We have developed a multidisciplinary experimental strategy to study structural and dynamic mechanistic aspects that underlie the Aβ assembly process. Utilizing this strategy, we explored the molecular basis leading to the perturbation of the Aβ assembly process by divalent metal ions, mainly Zn2+ ions. Using Zn2+ as reaction physiological relevant probes, it was demonstrated that Zn2+ rapidly (milliseconds) induce self-assembly of Aβ aggregates and stabilize them in a manner that prevents formation of Aβ fibrils. Importantly, the early-formed intermediates are substantially more neurotoxic than fibrils. Our results suggest that relevant Aβ modulators should be targeted against the rapidly evolved intermediate states of Aβ assembly. The design of such modulators is challenging, as they have to compete with different natural mediators (such as Zn2+) of Aβ aggregation, which diverse Aβ assemblies in both specific and nonspecific manners.

  8. Familial Alzheimer's disease mutations differentially alter amyloid β-protein oligomerization.

    Science.gov (United States)

    Gessel, Megan Murray; Bernstein, Summer; Kemper, Martin; Teplow, David B; Bowers, Michael T

    2012-11-21

    Although most cases of Alzheimer's disease (AD) are sporadic, ∼5% of cases are genetic in origin. These cases, known as familial Alzheimer's disease (FAD), are caused by mutations that alter the rate of production or the primary structure of the amyloid β-protein (Aβ). Changes in the primary structure of Aβ alter the peptide's assembly and toxic activity. Recently, a primary working hypothesis for AD has evolved where causation has been attributed to early, soluble peptide oligomer states. Here we posit that both experimental and pathological differences between FAD-related mutants and wild-type Aβ could be reflected in the early oligomer distributions of these peptides. We use ion mobility-based mass spectrometry to probe the structure and early aggregation states of three mutant forms of Aβ40 and Aβ42: Tottori (D7N), Flemish (A21G), and Arctic (E22G). Our results indicate that the FAD-related amino acid substitutions have no noticeable effect on Aβ monomer cross section, indicating there are no major structural changes in the monomers. However, we observe significant changes to the aggregation states populated by the various Aβ mutants, indicating that structural changes present in the monomers are reflected in the oligomers. Moreover, the early oligomer distributions differ for each mutant, suggesting a possible structural basis for the varied pathogenesis of different forms of FAD.

  9. Human J-protein DnaJB6b Cures a Subset of Saccharomyces cerevisiae Prions and Selectively Blocks Assembly of Structurally Related Amyloids.

    Science.gov (United States)

    Reidy, Michael; Sharma, Ruchika; Roberts, Brittany-Lee; Masison, Daniel C

    2016-02-19

    Human chaperone DnaJB6, an Hsp70 co-chaperone whose defects cause myopathies, protects cells from polyglutamine toxicity and prevents purified polyglutamine and Aβ peptides from forming amyloid. Yeast prions [URE3] and [PSI(+)] propagate as amyloid forms of Ure2 and Sup35 proteins, respectively. Here we find DnaJB6-protected yeast cells from polyglutamine toxicity and cured yeast of both [URE3] prions and weak variants of [PSI(+)] prions but not strong [PSI(+)] prions. Weak and strong variants of [PSI(+)] differ only in the structural conformation of their amyloid cores. In line with its anti-prion effects, DnaJB6 prevented purified Sup35NM from forming amyloids at 37 °C, which produce predominantly weak [PSI(+)] variants when used to infect yeast, but not at 4 °C, which produces mostly strong [PSI(+)] variants. Thus, structurally distinct amyloids composed of the same protein were differentially sensitive to the anti-amyloid activity of DnaJB6 both in vitro and in vivo. These findings have important implications for strategies using DnaJB6 as a target for therapy in amyloid disorders.

  10. A setup for simultaneous measurement of infrared spectra and light scattering signals: Watching amyloid fibrils grow from intact proteins

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yang; Maurer, Jürgen; Roth, Andreas; Vogel, Vitali; Winter, Ernst; Mäntele, Werner, E-mail: maentele@biophysik.uni-frankfurt.de [Institut für Biophysik, Goethe-Universität Frankfurt am Main, Max-von Laue-Straße 1, D-60438 Frankfurt am Main (Germany)

    2014-08-15

    A setup for the simultaneous measurement of mid-infrared spectra and static light scattering is described that can be used for the analysis of the formation of nanoscale and microscopic aggregates from smaller molecules to biopolymers. It can be easily integrated into sample chambers of infrared spectrometers or combined with laser beams from tunable infrared lasers. Here, its use for the analysis of the formation of amyloid fibrils from intact proteins is demonstrated. The formation of amyloid fibrils or plaques from proteins is a widespread and pathogenetic relevant process, and a number of diseases are caused and correlated with the deposition of amyloid fibrils in cells and tissues. The molecular mechanisms of these transformations, however, are still unclear. We report here the simultaneous measurement of infrared spectra and static light scattering for the analysis of fibril formation from egg-white lysozyme. The transformation of the native form into non-native forms rich in β-sheet structure is measured by analysis of the amide I spectral region in the infrared spectra, which is sensitive for local structures. At the same time, light scattering signals at forward direction as well as the forward/backward ratio, which are sensitive for the number of scattering centers and their approximate sizes, respectively, are collected for the analysis of fibril growth. Thermodynamic and kinetic parameters as well as mechanistic information are deduced from the combination of the two complementary techniques.

  11. The repeat domain of the melanosome fibril protein Pmel17 forms the amyloid core promoting melanin synthesis.

    Science.gov (United States)

    McGlinchey, Ryan P; Shewmaker, Frank; McPhie, Peter; Monterroso, Begoña; Thurber, Kent; Wickner, Reed B

    2009-08-18

    Pmel17 is a melanocyte protein necessary for eumelanin deposition 1 in mammals and found in melanosomes in a filamentous form. The luminal part of human Pmel17 includes a region (RPT) with 10 copies of a partial repeat sequence, pt.e.gttp.qv., known to be essential in vivo for filament formation. We show that this RPT region readily forms amyloid in vitro, but only under the mildly acidic conditions typical of the lysosome-like melanosome lumen, and the filaments quickly become soluble at neutral pH. Under the same mildly acidic conditions, the Pmel filaments promote eumelanin formation. Electron diffraction, circular dichroism, and solid-state NMR studies of Pmel17 filaments show that the structure is rich in beta sheet. We suggest that RPT is the amyloid core domain of the Pmel17 filaments so critical for melanin formation.

  12. Serum amyloid P (female protein) of the Syrian hamster. Gene structure and expression.

    Science.gov (United States)

    Rudnick, C M; Dowton, S B

    1993-10-15

    The structure and expression of the gene encoding serum amyloid P (SAP) component of the Syrian hamster have been studied by isolation of cosmid clones, nucleotide sequence analyses, and quantitation of nuclear run-on transcripts, nuclear RNA, mRNA, and protein levels. Hamster SAP, originally identified as female protein (FP), is a unique pentraxin because pretranslational expression of this gene is modulated by mediators of inflammation and sex steroids. SAP(FP) levels are high in sera from female hamsters and low in males. The response to inflammation is divergent; SAP(FP) levels decrease in females and increase in males during an acute phase response. The SAP(FP) gene encodes a 211 amino acid residue mature polypeptide as well as a 22-residue signal peptide. The intron/exon organization is similar to that of other pentraxins, but additional transcripts are generated from alternate polyadenylation sites in the 3' region. Circulating levels of SAP(FP) and the corresponding hepatic transcript levels are augmented by estrogen, while testosterone, dexamethasone, and progesterone cause a decrease in these levels. In addition the cytokines interleukin-1, -6, and tumor necrosis factor mediate a decrease in hepatic SAP(FP) transcript levels in female hamsters but did not cause a significant elevation of SAP(FP) mRNA in livers of male hamsters. The differences in expression of the SAP(FP) gene between male and female hamsters and between unstimulated male hamsters and male hamsters stimulated with an injection of lipopolysaccharide are due, at least in part, to alterations in transcription.

  13. α-Ketoacids as precursors for phenylalanine and tyrosine labelling in cell-based protein overexpression.

    Science.gov (United States)

    Lichtenecker, Roman J; Weinhäupl, Katharina; Schmid, Walther; Konrat, Robert

    2013-12-01

    (13)C-α-ketoacid metabolic precursors of phenylalanine and tyrosine effectively enter the metabolism of a protein overexpressing E. coli strain to label Phe- and Tyr-residues devoid of any cross-labelling. The methodology gives access to highly selective labelling patterns as valuable tools in protein NMR spectroscopy without the need of (15)N-chiral amino acid synthesis using organic chemistry.

  14. Bapineuzumab alters aβ composition: implications for the amyloid cascade hypothesis and anti-amyloid immunotherapy.

    Directory of Open Access Journals (Sweden)

    Alex E Roher

    Full Text Available The characteristic neuropathological changes associated with Alzheimer's disease (AD and other lines of evidence support the amyloid cascade hypothesis. Viewing amyloid deposits as the prime instigator of dementia has now led to clinical trials of multiple strategies to remove or prevent their formation. We performed neuropathological and biochemical assessments of 3 subjects treated with bapineuzumab infusions. Histological analyses were conducted to quantify amyloid plaque densities, Braak stages and the extent of cerebral amyloid angiopathy (CAA. Amyloid-β (Aβ species in frontal and temporal lobe samples were quantified by ELISA. Western blots of amyloidprecursor protein (AβPP and its C-terminal (CT fragments as well as tau species were performed. Bapineuzumab-treated (Bapi-AD subjects were compared to non-immunized age-matched subjects with AD (NI-AD and non-demented control (NDC cases. Our study revealed that Bapi-AD subjects exhibited overall amyloid plaque densities similar to those of NI-AD cases. In addition, CAA was moderate to severe in NI-AD and Bapi-AD patients. Although histologically-demonstrable leptomeningeal, cerebrovascular and neuroparenchymal-amyloid densities all appeared unaffected by treatment, Aβ peptide profiles were significantly altered in Bapi-AD subjects. There was a trend for reduction in total Aβ42 levels as well as an increase in Aβ40 which led to a corresponding significant decrease in Aβ42:Aβ40 ratio in comparison to NI-AD subjects. There were no differences in the levels of AβPP, CT99 and CT83 or tau species between Bapi-AD and NI-AD subjects. The remarkable alteration in Aβ profiles reveals a dynamic amyloid production in which removal and depositional processes were apparently perturbed by bapineuzumab therapy. Despite the alteration in biochemical composition, all 3 immunized subjects exhibited continued cognitive decline.

  15. Self-assembly of a nine-residue amyloid-forming peptide fragment of SARS corona virus E-protein: mechanism of self aggregation and amyloid-inhibition of hIAPP.

    Science.gov (United States)

    Ghosh, Anirban; Pithadia, Amit S; Bhat, Jyotsna; Bera, Supriyo; Midya, Anupam; Fierke, Carol A; Ramamoorthy, Ayyalusamy; Bhunia, Anirban

    2015-04-01

    Molecular self-assembly, a phenomenon widely observed in nature, has been exploited through organic molecules, proteins, DNA, and peptides to study complex biological systems. These self-assembly systems may also be used in understanding the molecular and structural biology which can inspire the design and synthesis of increasingly complex biomaterials. Specifically, use of these building blocks to investigate protein folding and misfolding has been of particular value since it can provide tremendous insights into peptide aggregation related to a variety of protein misfolding diseases, or amyloid diseases (e.g., Alzheimer's disease, Parkinson's disease, type-II diabetes). Herein, the self-assembly of TK9, a nine-residue peptide of the extra membrane C-terminal tail of the SARS corona virus envelope, and its variants were characterized through biophysical, spectroscopic, and simulated studies, and it was confirmed that the structure of these peptides influences their aggregation propensity, hence, mimicking amyloid proteins. TK9, which forms a beta-sheet rich fibril, contains a key sequence motif that may be critical for beta-sheet formation, thus making it an interesting system to study amyloid fibrillation. TK9 aggregates were further examined through simulations to evaluate the possible intra- and interpeptide interactions at the molecular level. These self-assembly peptides can also serve as amyloid inhibitors through hydrophobic and electrophilic recognition interactions. Our results show that TK9 inhibits the fibrillation of hIAPP, a 37 amino acid peptide implicated in the pathology of type-II diabetes. Thus, biophysical and NMR experimental results have revealed a molecular level understanding of peptide folding events, as well as the inhibition of amyloid-protein aggregation are reported.

  16. Human Islet Amyloid Polypeptide

    DEFF Research Database (Denmark)

    Kosicka, Iga

    2014-01-01

    Diabetes mellitus type II is a metabolic disease affecting millions of people worldwide. The disease is associated with occurence of insoluble, fibrillar, protein aggregates in islets of Langerhans in the pancreas - islet amyloid. The main constituent of these protein fibers is the human islet...... of diabetes type II, while revealing the structure(s) of islet amyloid fibrils is necessary for potential design of therapeutic agents....

  17. The β-amyloid protein induces S100β expression in rat hippocampus through a mechanism that involves IL-1

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective To explore the effect of β-amyloid protein (Aβ) on S100β expression in rat hippocampus and its mechanisms. Methods At 7 days after bilateral stereotaxis injection of different dose of fibrillar Aβ 25-35 and interluekin-1 receptor antagonist (IL-1ra) into the rat CA1 region, the learning and memory abilities of rats were tested with passive avoidance task. Amyloid deposition was detected by using Congo red staining technique. Nissl staining and immunohistochemical techniques were used to analyze the number of neurons, and GFAP and the S100β expression in hippocampal CA1 region , respectively. Results After fibrillar Aβ injection, the step-through latency of rats was significantly shortened compared to that of the control group. The GFAP positive astrocytes were found surrounding amyloid deposition. Neuronal loss occurred in the pyramidal cell layer of CA1 region. The number of S100β positive cells in Aβ-treated group was significantly increased compared with that in the control group. After IL-1ra injection, the number of S100β positive cells was significantly decreased. Conclusion Intrahippocampal injection of Aβ 25-35 could cause similar pathologic changes of Alzheimer's disease. Aβ 25-35 was capable of up-regulating S100β expression in a dose-dependent manner. The injection of IL-1ra could attenuate the effect of Aβ on S100β expression.

  18. The involvement of homocysteine in stress-induced Aβ precursor protein misprocessing and related cognitive decline in rats.

    Science.gov (United States)

    Xie, Fang; Zhao, Yun; Ma, Jing; Gong, Jing-Bo; Wang, Shi-Da; Zhang, Liang; Gao, Xiu-Jie; Qian, Ling-Jia

    2016-09-01

    Chronic stress is a risk factor in the development of cognitive decline and even Alzheimer's disease (AD), although its underlying mechanism is not fully understood. Our previous data demonstrated that the level of homocysteine (Hcy) was significantly elevated in the plasma of stressed animals, which suggests the possibility that Hcy is a link between stress and cognitive decline. To test this hypothesis, we compared the cognitive function, plasma concentrations of Hcy, and the brain beta-amyloid (Aβ) level between rats with or without chronic unexpected mild stress (CUMS). A lower performance by rats in behavioral tests indicated that a significant cognitive decline was induced by CUMS. Stress also disturbed the normal processing of Aβ precursor protein (APP) and resulted in the accumulation of Aβ in the brains of rats, which showed a positive correlation with the hyperhomocysteinemia (HHcy) that appeared in stressed rats. Hcy-targeting intervention experiments were used to verify further the involvement of Hcy in stress-induced APP misprocessing and related cognitive decline. The results showed that diet-induced HHcy could mimic the cognitive impairment and APP misprocessing in the same manner as CUMS, while Hcy reduction by means of vitamin B complex supplements and betaine could alleviate the cognitive deficits and dysregulation of Aβ metabolism in CUMS rats. Taken together, the novel evidence from our present study suggests that Hcy is likely to be involved in chronic stress-evoked APP misprocessing and related cognitive deficits. Our results also suggested the possibility of Hcy as a target for therapy and the potential value of vitamin B and betaine intake in the prevention of stress-induced cognitive decline.

  19. Identification of UDP-linked murein precursors as contaminants in recombinant proteins of low molecular weight.

    Science.gov (United States)

    Ram, M K; Andrade, L J; Phillips, T B; van Schravendijk, M R

    1999-11-01

    The A(280)/A(260) ratio of a purified protein is frequently used as an indication of the purity of the preparation with respect to nucleic acids. We show here that for low-molecular-weight recombinant proteins purified from Escherichia coli, a low A(280)/A(260) ratio can also result from contamination with UDP-linked murein precursors derived from bacterial cell wall metabolism. Although these precursors are small molecules of molecular weight 1000-1200, they comigrate in gel filtration with recombinant human FKBP (MW 11,820). This gel filtration behavior, which is distinct from that of unmodified mononucleotides, does not reflect binding interactions with FKBP, but is an intrinsic property of these precursors. Therefore, these molecules would be expected to copurify with other low-molecular-weight proteins, especially in the abbreviated purification protocols made possible by freeze-thaw release of recombinant proteins from E. coli (Johnson, B. H., and Hecht, M. H. (1994) BioTechnology 12, 1357-1360). Several alternative strategies are discussed for integrating these findings into the design of improved purification procedures for low-molecular-weight recombinant proteins.

  20. Microglial Amyloid-β1-40 Phagocytosis Dysfunction Is Caused by High-Mobility Group Box Protein-1: Implications for the Pathological Progression of Alzheimer’s Disease

    Directory of Open Access Journals (Sweden)

    Kazuyuki Takata

    2012-01-01

    Full Text Available In Alzheimer disease (AD patient brains, the accumulation of amyloid-β (Aβ peptides is associated with activated microglia. Aβ is derived from the amyloid precursor protein; two major forms of Aβ, that is, Aβ1-40 (Aβ40 and Aβ1-42 (Aβ42, exist. We previously reported that rat microglia phagocytose Aβ42, and high mobility group box protein 1 (HMGB1, a chromosomal protein, inhibits phagocytosis. In the present study, we investigated the effects of exogenous HMGB1 on rat microglial Aβ40 phagocytosis. In the presence of exogenous HMGB1, Aβ40 markedly increased in microglial cytoplasm, and the reduction of extracellular Aβ40 was inhibited. During this period, HMGB1 was colocalized with Aβ40 in the cytoplasm. Furthermore, exogenous HMGB1 inhibited the degradation of Aβ40 induced by the rat microglial cytosolic fraction. Thus, extracellular HMGB1 may internalize with Aβ40 in the microglial cytoplasm and inhibit Aβ40 degradation by microglia. This may subsequently delay Aβ40 clearance. We further confirmed that in AD brains, the parts of senile plaques surrounded by activated microglia are composed of Aβ40, and extracellular HMGB1 is deposited on these plaques. Taken together, microglial Aβ phagocytosis dysfunction may be caused by HMGB1 that accumulates extracellularly on Aβ plaques, and it may be critically involved in the pathological progression of AD.

  1. Serum Amyloid A Protein Concentration in Blood is Influenced by Genetic Differences in the Cheetah (Acinonyx jubatus).

    Science.gov (United States)

    Franklin, Ashley D; Schmidt-Küntzel, Anne; Terio, Karen A; Marker, Laurie L; Crosier, Adrienne E

    2016-03-01

    Systemic amyloid A (AA) amyloidosis is a major cause of morbidity and mortality among captive cheetahs. The self-aggregating AA protein responsible for this disease is a byproduct of serum amyloid A (SAA) protein degradation. Transcriptional induction of the SAA1 gene is dependent on both C/EBPβ and NF-κB cis-acting elements within the promoter region. In cheetahs, 2 alleles exist for a single guanine nucleotide deletion in the putative NF-κB binding site. In this study, a novel genotyping assay was developed to screen for the alleles. The results show that the SAA1A (-97delG) allele is associated with decreased SAA protein concentrations in the serum of captive cheetahs (n = 58), suggesting genetic differences at this locus may be affecting AA amyloidosis prevalence. However, there was no significant difference in the frequency of the SAA1A (-97delG) allele between individuals confirmed AA amyloidosis positive versus AA amyloidosis negative at the time of necropsy (n = 48). Thus, even though there is evidence that having more copies of the SAA1A (-97delG) allele results in a potentially protective decrease in serum concentrations of SAA protein in captive cheetahs, genotype is not associated with this disease within the North American population. These results suggest that other factors are playing a more significant role in the pathogenesis of AA amyloidosis among captive cheetahs.

  2. Comparison of serum amyloid A and C-reactive protein as diagnostic markers of systemic inflammation in dogs

    DEFF Research Database (Denmark)

    Christensen, Michelle Brønniche; Langhorn, Rebecca; Goddard, Amelia

    2014-01-01

    The diagnostic performance of canine serum amyloid A (SAA) was compared with that of C-reactive protein (CRP) in the detection of systemic inflammation in dogs. Sera from 500 dogs were retrospectively included in the study. C-reactive protein and SAA were measured using validated automated assays....... The overlap performance, clinical decision limits, overall diagnostic performance, correlations, and agreement in the clinical classification between these 2 diagnostic markers were compared. Significantly higher concentrations of both proteins were detected in dogs with systemic inflammation (SAA range: 48.......75 to > 2700 mg/L; CRP range: 0.4 to 907.4 mg/L) compared to dogs without systemic inflammation (SAA range: 1.06 to 56.4 mg/L; CRP range: 0.07 to 24.7 mg/L). Both proteins were shown to be sensitive and specific markers of systemic inflammation in dogs. Significant correlations and excellent diagnostic...

  3. Proteomic profiling of the mitochondrial ribosome identifies Atp25 as a composite mitochondrial precursor protein.

    Science.gov (United States)

    Woellhaf, Michael W; Sommer, Frederik; Schroda, Michael; Herrmann, Johannes M

    2016-10-15

    Whereas the structure and function of cytosolic ribosomes are well characterized, we only have a limited understanding of the mitochondrial translation apparatus. Using SILAC-based proteomic profiling, we identified 13 proteins that cofractionated with the mitochondrial ribosome, most of which play a role in translation or ribosomal biogenesis. One of these proteins is a homologue of the bacterial ribosome-silencing factor (Rsf). This protein is generated from the composite precursor protein Atp25 upon internal cleavage by the matrix processing peptidase MPP, and in this respect, it differs from all other characterized mitochondrial proteins of baker's yeast. We observed that cytosolic expression of Rsf, but not of noncleaved Atp25 protein, is toxic. Our results suggest that eukaryotic cells face the challenge of avoiding negative interference from the biogenesis of their two distinct translation machineries.

  4. Melatonin attenuates β-amyloid-induced inhibition of neurofilament expression

    Institute of Scientific and Technical Information of China (English)

    Ying-chun ZHANG; Ze-fen WANG; Qun WANG; Yi-peng WANG; Jian-zhi WANG

    2004-01-01

    AIM: To explore the effect of β-amyloid (Aβ) on metabolism of cytoskeletal protein neurofilament, and search for effective cure to the lesion. METHODS: Wild type murine neuroblastoma N2a (N2awt) and N2a stably transfected with wild type amyloid precursor protein (N2aAPP) were cultured. Sandwich ELISA, immunocytochemistry, and Western blot were used respectively to measure the level of Aβ, the expression and phosphorylation of neurofilament proteins. RESULTS: The immunoreactivity of neurofilament protein was almost abolished in N2aAPP, which beard a significantly higher level of Aβ. Melatonin effectively decreased the level of Aβ, and restored partially the level of phosphorylated and non-phosphorylated neurofilament in N2aAPP. CONCLUSION: Overproduction of Aβ inhibits neurofilament expression, and melatonin attenuates the Aβ-induced lesion in cytoskeletal protein.

  5. Modeling amyloids in bacteria

    Directory of Open Access Journals (Sweden)

    Villar-Piqué Anna

    2012-12-01

    Full Text Available Abstract An increasing number of proteins are being shown to assemble into amyloid structures, self-seeding fibrillar aggregates that may lead to pathological states or play essential biological functions in organisms. Bacterial cell factories have raised as privileged model systems to understand the mechanisms behind amyloid assembly and the cellular fitness cost associated to the formation of these aggregates. In the near future, these bacterial systems will allow implementing high-throughput screening approaches to identify effective modulators of amyloid aggregation.

  6. Comparable autoantibody serum levels against amyloid- and inflammation-associated proteins in Parkinson's disease patients and controls.

    Directory of Open Access Journals (Sweden)

    Walter Maetzler

    Full Text Available Naturally occurring autoantibodies (NAbs against a number of potentially disease-associated cellular proteins, including Amyloid-beta1-42 (Abeta1-42, Alpha-synuclein (Asyn, myelin basic protein (MBP, myelin oligodendrocyte glycoprotein (MOG, and S100 calcium binding protein B (S100B have been suggested to be associated with neurodegenerative disorders, in particular Alzheimer's (AD and Parkinson's disease (PD. Whereas the (reduced occurrence of specific NAbs in AD is widely accepted, previous literature examining the relation of these NAb titres between PD patients and controls, as well as comparing these levels with demographic and clinical parameters in PD patients have produced inconsistent findings. We therefore aimed, in a cross-sectional approach, to determine serum titres of the above NAbs in a cohort of 93 PD patients (31 of them demented and 194 controls. Levels were correlated with demographic and clinical variables, cerebrospinal fluid Abeta1-42, total tau and phospho-tau levels, as well as with single nucleotide polymorphisms (SNPs of genes which either have been reported to influence the immune system, the amyloid cascade or the occurrence of PD (ApoE, GSK3B, HLA-DRA, HSPA5, SNCA, and STK39. The investigated NAb titres were neither significantly associated with the occurrence of PD, nor with demographic and clinical parameters, neurodegenerative markers or genetic variables. These results argue against a major potential of blood-borne parameters of the adaptive immune system to serve as trait or state markers in PD.

  7. Occupational exposure levels of bioaerosol components are associated with serum levels of the acute phase protein Serum Amyloid A in greenhouse workers

    DEFF Research Database (Denmark)

    Madsen, Anne Mette; Thilsing, Trine; Bælum, Jesper;

    2016-01-01

    to elevated levels of bioaerosols. The objective of this study is to assess whether greenhouse workers personal exposure to bioaerosol components was associated with serum levels of the acute phase proteins Serum Amyloid A (SAA) and C-reactive protein (CRP). METHODS: SAA and CRP levels were determined...

  8. Sycamore amyloplasts can import and process precursors of nuclear encoded chloroplast proteins.

    Science.gov (United States)

    Strzalka, K; Ngernprasirtsiri, J; Watanabe, A; Akazawa, T

    1987-12-16

    Amyloplasts isolated from white-wild suspension-cultured cells of sycamore (Acer pseudoplatanus L.) are found to import and process the precursor of the small subunit (pS) of ribulose-1,5-bisphosphate carboxylase/oxygenase of spinach, but they lack the ability to form its holoenzyme due to the absence of both the large subunit and its binding-protein. They also import the precursor of the 33-kDa extrinsic protein (p33-kDa) of the O2-evolving complex of Photosystem II from spinach, but process is only to an intermediate form (i33-kDa). Chloroplasts from green-mutant cells of sycamore process p33-kDa to its mature form in this heterologous system. These results suggest that the thylakoid-associated protease responsible for the second processing step of p33-kDa is missing in amyloplasts, possibly due to the absence of thylakoid-membranes. In contrast, the apparent import of the precursor of the light-harvesting chlorophyll a/b-binding apoprotein (pLHCP) from spinach was not detected. Sycamore amyloplasts may lack the ability to import this particular thylakoid-protein, or rapidly degrade the imported molecules in the absence of thylakoid-membranes for their proper insertion.

  9. The epsilon isoform of 14-3-3 protein is a component of the prion protein amyloid deposits of Gerstmann-Sträussler-Scheinker disease.

    Science.gov (United States)

    Di Fede, Giuseppe; Giaccone, Giorgio; Limido, Lucia; Mangieri, Michela; Suardi, Silvia; Puoti, Gianfranco; Morbin, Michela; Mazzoleni, Giulia; Ghetti, Bernardino; Tagliavini, Fabrizio

    2007-02-01

    The 14-3-3 proteins are highly conserved, ubiquitous molecules involved in a variety of biologic events, such as transduction pathway modulation, cell cycle control, and apoptosis. Seven isoforms have been identified that are abundant in the brain, preferentially localized in neurons. Remarkable increases in 14-3-3 are seen in the cerebrospinal fluid of patients with Creutzfeldt-Jakob disease (CJD), and it has been found in pathologic inclusions of several neurodegenerative diseases. Moreover, the zeta isoform has been detected in prion protein (PrP) amyloid deposits of CJD patients. To further investigate the cerebral distribution of 14-3-3 in prion-related encephalopathies, we carried out an immunohistochemical and biochemical analysis of brain tissue from patients with Gerstmann-Sträussler-Scheinker disease (GSS) and sporadic, familial and acquired forms of CJD, using specific antibodies against the seven 14-3-3 isoforms. The study showed a strong immunoreactivity of PrP amyloid plaques of GSS patients for the 14-3-3 epsilon isoform, but not for the other isoforms. The epsilon isoform of 14-3-3 was not found in PrP deposits of CJD. These results indicate that the epsilon isoform of 14-3-3 is a component of PrP amyloid deposits of GSS and suggest that this is the sole 14-3-3 isoform specifically involved in the neuropathologic changes associated with this disorder.

  10. Pathogenesis of cerebral amyloid angiopathy.

    NARCIS (Netherlands)

    Rensink, A.A.M.; Waal, R.M.W. de; Kremer, H.P.H.; Verbeek, M.M.

    2003-01-01

    Cerebral amyloid angiopathy (CAA) is the result of the deposition of an amyloidogenic protein in cortical and leptomeningeal vessels. The most common type of CAA is caused by amyloid beta-protein (Abeta), which is particularly associated with Alzheimer's disease (AD). Excessive Abeta-CAA formation c

  11. Investigation on apoptosis of neuronal cells induced by Amyloid beta-Protein

    Institute of Scientific and Technical Information of China (English)

    罗本燕; 徐增斌; 陈智; 陈峰; 唐敏

    2004-01-01

    Objective: To construct a PC12 cell strain with neuronal differentiation, and observe the apoptosis and pro-liferation activity effects induced these cells by Amyloid beta-Protein (Aβ3-43). Methods: 1) PC12 cells in logarithmic growth phase were subcultured for 24 h. After the culture fluid was changed, the cells were treated with Rat-β-NGF and cultured for 9 days. 2) Neuronal differentiation of PC 12 cells in logarithmic growth phase were divided into four groups:control group (0), experimental group (1), experimental group (2) and experimental group (3). The concentrations of Aβ in the four groups were 0 μmol/L, 1.25 μmol/L, 2.5 μmol/L and 5 μmol/L, respectively. The cells were harvested at 24, 48 and 72 h later and stained with AnnexinV-FITC/PI after centrifugation and washing. Then flow cytometry was conducted to examine the apoptosis percentage. 3) NGF-induced PC12 cells were selected and Aβ with different concentrations was added. The final concentrations of Aβ were 0 μmol/L, 1.25 μmol/L, 2.5 μmol/L and 5 μmol/L, respectively. After the cells were incubated in an atmosphere of 5% CO2 at 37 ℃ in an incubator for 72 h, the OD values were examined. Results: 1)Neuronal differentiated PC12 cell lines were successfully established. 2) Flow cytometric examination indicated that Aβ(1.25, 2.5, and 5.0 μmol/L) could effectively induce apoptosis of neuronal-differented cells at the 24 h, 48 h and 72 h time points. 3) Aβ (0-5.00 μmol/L) had no obvious effect on proliferation or restraining of the neuronal differentiation of the PC 12 cells after a 72 h interacting process. Conclusion: This investigation revealed successful neuronal differentiation of the PC12 cell strain. The induction of apoptosis of the neurocytes by various concentrations of Aβ was observed and the in-fluence of Aβ on induced proliferation of PC 12 cells by Rat-β-NGF was revealed. This study may provide basis for future research on the molecular cure of AD and interdiction of AD

  12. On the origin of Alzheimer's disease. Trials and tribulations of the amyloid hypothesis.

    Science.gov (United States)

    Castello, Michael A; Soriano, Salvador

    2014-01-01

    The amyloid cascade hypothesis, which implicates the amyloid Aβ peptide as the pathological initiator of both familial and sporadic, late onset Alzheimer's disease (AD), continues to guide the majority of research. We believe that current evidence does not support the amyloid cascade hypothesis for late onset AD. Instead, we propose that Aβ is a key regulator of brain homeostasis. During AD, while Aβ accumulation may occur in the long term in parallel with disease progression, it does not contribute to primary pathogenesis. This view predicts that amyloid-centric therapies will continue to fail, and that progress in developing successful alternative therapies for AD will be slow until closer attention is paid to understanding the physiological function of Aβ and its precursor protein.

  13. Monte Carlo simulations of protein amyloid formation reveal origin of sigmoidal aggregation kinetics.

    Science.gov (United States)

    Linse, Björn; Linse, Sara

    2011-07-01

    Severe conditions and lack of cure for many amyloid diseases make it highly desired to understand the underlying principles of formation of fibrillar aggregates (amyloid). Here, amyloid formation from peptides was studied using Monte Carlo simulations. Systems of 20, 50, 100, 200 or 500 hexapeptides were simulated. Association kinetics were modeled equal for fibrillar and other (inter- and intra-peptide) contacts and assumed to be faster the lower the effective contact order, which represents the distance in space. Attempts to form contacts were thus accepted with higher probability the lower the effective contact order, whereby formation of new contacts next to preexisting ones is favored by shorter physical separation. Kinetic discrimination was invoked by using two different life-times for formed contacts. Contacts within amyloid fibrils were assumed to have on average longer life-time than other contacts. We find that the model produces fibrillation kinetics with a distinct lag phase, and that the fibrillar contacts need to dissociate on average 5-20 times slower than all other contacts for the fibrillar structure to dominate at equilibrium. Analysis of the species distribution along the aggregation process shows that no other intermediate is ever more populated than the dimer. Instead of a single nucleation event there is a concomitant increase in average aggregate size over the whole system, and the occurrence of multiple parallel processes makes the process more reproducible the larger the simulated system. The sigmoidal shape of the aggregation curves arises from cooperativity among multiple interactions within each pair of peptides in a fibril. A governing factor is the increasing probability as the aggregation process proceeds of neighboring reinforcing contacts. The results explain the very strong bias towards cross β-sheet fibrils in which the possibilities for cooperativity among interactions involving neighboring residues and the repetitive use of

  14. Polymorphism of amyloid fibrils formed by a peptide from the yeast prion protein Sup35: AFM and Tip-Enhanced Raman Scattering studies

    Energy Technology Data Exchange (ETDEWEB)

    Krasnoslobodtsev, Alexey V., E-mail: akrasnos@unomaha.edu [Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198 (United States); Department of Physics, University of Nebraska Omaha, Omaha, NE 68182 (United States); Deckert-Gaudig, Tanja [IPHT-Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, D-07745 Jena (Germany); Zhang, Yuliang [Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198 (United States); Deckert, Volker [IPHT-Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, D-07745 Jena (Germany); Institute for Physical Chemistry and Abbe Center of Photonics, University of Jena, Helmholtzweg 4, D-07743 Jena (Germany); Lyubchenko, Yuri L., E-mail: ylyubchenko@unmc.edu [Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198 (United States)

    2016-06-15

    Aggregation of prion proteins is the cause of various prion related diseases. The infectious form of prions, amyloid aggregates, exist as multiple strains. The strains are thought to represent structurally different prion protein molecules packed into amyloid aggregates, but the knowledge on the structure of different types of aggregates is limited. Here we report on the use of AFM (Atomic Force Microscopy) and TERS (Tip-Enhanced Raman Scattering) to study morphological heterogeneity and access underlying conformational features of individual amyloid aggregates. Using AFM we identified the morphology of amyloid fibrils formed by the peptide (CGNNQQNY) from the yeast prion protein Sup35 that is critically involved in the aggregation of the full protein. TERS results demonstrate that morphologically different amyloid fibrils are composed of a distinct set of conformations. Fibrils formed at pH 5.6 are composed of a mixture of peptide conformations (β-sheets, random coil and α-helix) while fibrils formed in pH~2 solution primarily have β-sheets. Additionally, peak positions in the amide III region of the TERS spectra suggested that peptides have parallel arrangement of β-sheets for pH~2 fibrils and antiparallel arrangement for fibrils formed at pH 5.6. We also developed a methodology for detailed analysis of the peptide secondary structure by correlating intensity changes of Raman bands in different regions of TERS spectra. Such correlation established that structural composition of peptides is highly localized with large contribution of unordered secondary structures on a fibrillar surface. - Highlights: • Amyloid polymorphs were characterized by AFM and TERS. • A mixture of peptide secondary structures in fibrils were identified using TERS. • TERS recognizes packing arrangement (parallel versus antiparallel) of peptides. • TERS is a powerful tool for high resolution structural analysis of fibrils.

  15. Highly conserved residues in the helical domain of dengue virus type 1 precursor membrane protein are involved in assembly, precursor membrane (prM) protein cleavage, and entry.

    Science.gov (United States)

    Hsieh, Szu-Chia; Wu, Yi-Chieh; Zou, Gang; Nerurkar, Vivek R; Shi, Pei-Yong; Wang, Wei-Kung

    2014-11-28

    The envelope and precursor membrane (prM) proteins of dengue virus (DENV) are present on the surface of immature virions. During maturation, prM protein is cleaved by furin protease into pr peptide and membrane (M) protein. Although previous studies mainly focusing on the pr region have identified several residues important for DENV replication, the functional role of M protein, particularly the α-helical domain (MH), which is predicted to undergo a large conformational change during maturation, remains largely unknown. In this study, we investigated the role of nine highly conserved MH domain residues in the replication cycle of DENV by site-directed mutagenesis in a DENV1 prME expression construct and found that alanine substitutions introduced to four highly conserved residues at the C terminus and one at the N terminus of the MH domain greatly affect the production of both virus-like particles and replicon particles. Eight of the nine alanine mutants affected the entry of replicon particles, which correlated with the impairment in prM cleavage. Moreover, seven mutants were found to have reduced prM-E interaction at low pH, which may inhibit the formation of smooth immature particles and exposure of prM cleavage site during maturation, thus contributing to inefficient prM cleavage. Taken together, these results are the first report showing that highly conserved MH domain residues, located at 20-38 amino acids downstream from the prM cleavage site, can modulate the prM cleavage, maturation of particles, and virus entry. The highly conserved nature of these residues suggests potential targets of antiviral strategy.

  16. Amyloid Beta and Tau Proteins as Therapeutic Targets for Alzheimer’s Disease Treatment: Rethinking the Current Strategy

    Directory of Open Access Journals (Sweden)

    Siddhartha Mondragón-Rodríguez

    2012-01-01

    Full Text Available Alzheimer’s disease (AD is defined by the concurrence of accumulation of abnormal aggregates composed of two proteins: Amyloid beta (Aβ and tau, and of cellular changes including neurite degeneration and loss of neurons and cognitive functions. Based on their strong association with disease, genetically and pathologically, it is not surprising that there has been a focus towards developing therapies against the aggregated structures. Unfortunately, current therapies have but mild benefit. With this in mind we will focus on the relationship of synaptic plasticity with Aβ and tau protein and their role as potential targets for the development of therapeutic drugs. Finally, we will provide perspectives in developing a multifactorial strategy for AD treatment.

  17. Evaluation of Sialic Acid and Acute Phase Proteins (Haptoglobin and Serum Amyloid A in Clinical and Subclinical Bovine Mastitis

    Directory of Open Access Journals (Sweden)

    S. Nazifi*, M. Haghkhah1, Z. Asadi, M. Ansari-Lari2, M. R. Tabandeh3, Z. Esmailnezhad and M. Aghamiri

    2011-01-01

    Full Text Available The present study was conducted to evaluate the concentrations of sialic acids (total, lipid bound and protein bound and their correlation with acute phase proteins (haptoglobin and serum amyloid A in clinical and subclinical mastitis of cattle. Thirty subclinical mastitic cows with positive California mastitis test (CMT test and no clinical signs of mastitis, 10 clinical mastitic cows and 10 healthy cows with negative CMT test and normal somatic cell count were selected. Milk and blood samples were collected after confirmation of clinical and subclinical mastitis by somatic cell count and bacterial identification. Serum haptoglobin (Hp, serum amyloid A (SAA, total sialic acid (TSA, lipid bound sialic acid (LBSA and protein bound sialic acid (PBSA were measured by validated standard methods. Haptoglobin and SAA increased significantly in both types of mastitis compared with control group (P<0.001. However, the ratio of HP/SAA was significantly different from the control group only in clinical mastitis. The results showed that TSA and LBSA were significantly different in control group compared with clinical and subclinical mastitis (P<0.001. Protein bound sialic acid did not change in subclinical mastitis in comparison with control group (P=0.86. There was positive correlation between LBSA and PBSA in clinical mastitis (r=0.72, P=0.02 whereas significant negative correlation was observed between LBSA and PBSA in subclinical mastitis (r=-0.62, P<0.001. Results also showed no correlation between Hp and SAA with each other or with any other parameters in study groups.

  18. Antioxidant role of amyloid β protein in cell-free and biological systems: implication for the pathogenesis of Alzheimer disease.

    Science.gov (United States)

    Sinha, Maitrayee; Bhowmick, Pritha; Banerjee, Anindita; Chakrabarti, Sasanka

    2013-03-01

    In contrast to many studies showing the pro-oxidative nature of amyloid peptide, this work shows that aggregated Aβ42 peptide in varying concentrations (2-20 μM) in cell-free systems inhibits the formation of hydroxyl radicals and H(2)O(2) from a mixture of iron (20 μM FeSO(4)) and ascorbate (2mM) as measured by benzoate hydroxylation assay and coumarin carboxylic acid assay. Aggregated Aβ42 in similar concentrations further prevents protein and lipid oxidation in isolated rat brain mitochondria incubated alone or with FeSO(4) and ascorbate. Moreover, mitochondria exposed to FeSO(4) and ascorbate show enhanced formation of reactive oxygen species and this phenomenon is also abolished by aggregated Aβ42. It is suggested that the antioxidant property of Aβ42 in various systems is mediated by metal chelation and it is nearly as potent as a typical metal chelator, such as diethylenetriaminepentaacetic acid, in preventing oxidative damage. However, aggregated Aβ42 causes mitochondrial functional impairment in the form of membrane depolarization and a loss of phosphorylation capacity without involving reactive oxygen species in the process. Thus, the present results suggest that the amyloid peptide exhibits a protective antioxidant role in biological systems, but also has toxic actions independent of oxidative stress.

  19. Telencephalin protects PAJU cells from amyloid beta protein-induced apoptosis by activating the ezrin/radixin/moesin protein family/phosphatidylinositol-3-kinase/protein kinase B pathway

    Institute of Scientific and Technical Information of China (English)

    Heping Yang; Dapeng Wu; Xiaojie Zhang; Xiang Wang; Yi Peng; Zhiping Hu

    2012-01-01

    Telencephalin is a neural glycoprotein that reduces apoptosis induced by amyloid beta protein in the human neural tumor cell line PAJU.In this study,we examined the role of the ezrin/radixin/moesin protein family/phosphatidylinositol-3-kinase/protein kinase B pathway in this process.Western blot analysis demonstrated that telencephalin,phosphorylated ezrin/radixin/moesin and phosphatidylinositol-3-kinase/protein kinase B were not expressed in PAJU cells transfected with empty plasmid,while they were expressed in PAJU cells transfected with a telencephalin expression plasmid.After treatment with 1.0 nM amyloid beta protein 42,expression of telencephalin and phosphorylated phosphatidylinositol-3-kinase/protein kinase B in the transfected cells gradually diminished,while levels of phosphorylated ezrin/radixin/moesin increased.In addition,the high levels of telencephalin,phosphorylated ezrin/radixin/moesin and phosphatidylinositol-3-kinase/protein kinase B expression in PAJU cells transfected with a telencephalin expression plasmid could be suppressed by the phosphatidylinositol-3-kinase inhibitor LY294002.These findings indicate that telencephalin activates the ezrin/radixin/moesin family/phosphatidylinositol-3-kinase/protein kinase B pathway and protects PAJU cells from amyloid beta protein-induced apoptosis.

  20. THE OPEP COARSE-GRAINED PROTEIN MODEL: FROM SINGLE MOLECULES, AMYLOID FORMATION, ROLE OF MACROMOLECULAR CROWDING AND HYDRODYNAMICS TO RNA/DNA COMPLEXES

    OpenAIRE

    Sterpone, Fabio; Melchionna, Simone; Tuffery, Pierre; Pasquali, Samuela; Mousseau, Normand; Cragnolini, Tristan; Chebaro, Yassmine; Saint-Pierre, Jean-Francois; Kalimeri, Maria; Barducci, Alessandro; Laurin, Yohan; Tek, Alex; Baaden, Marc; Nguyen, Phuong Hoang; Derreumaux, Philippe

    2014-01-01

    The OPEP coarse-grained protein model has been applied to a wide range of applications since its first release 15 years ago. The model, which combines energetic and structural accuracy and chemical specificity, allows studying single protein properties, DNA/RNA complexes, amyloid fibril formation and protein suspensions in a crowded environment. Here we first review the current state of the model and the most exciting applications using advanced conformational sampling methods. We then presen...

  1. Hacking the code of amyloid formation: the amyloid stretch hypothesis.

    Science.gov (United States)

    Pastor, M Teresa; Esteras-Chopo, Alexandra; Serrano, Luis

    2007-01-01

    Many research efforts in the last years have been directed towards understanding the factors determining protein misfolding and amyloid formation. Protein stability and amino acid composition have been identified as the two major factors in vitro. The research of our group has been focused on understanding the relationship between amino acid sequence and amyloid formation. Our approach has been the design of simple model systems that reproduce the biophysical properties of natural amyloids. An amyloid sequence pattern was extracted that can be used to detect amyloidogenic hexapeptide stretches in proteins. We have added evidence supporting that these amyloidogenic stretches can trigger amyloid formation by nonamyloidogenic proteins. Some experimental results in other amyloid proteins will be analyzed under the conclusions obtained in these studies. Our conclusions together with evidences from other groups suggest that amyloid formation is the result of the interplay between a decrease of protein stability, and the presence of highly amyloidogenic regions in proteins. As many of these results have been obtained in vitro, the challenge for the next years will be to demonstrate their validity in in vivo systems.

  2. Aggregation properties of a short peptide that mediates amyloid fibril formation in model proteins unrelated to disease

    Indian Academy of Sciences (India)

    Nitin Chaudhary; Shashi Singh; Ramakrishnan Nagaraj

    2011-09-01

    Short peptides have been identified from amyloidogenic proteins that form amyloid fibrils in isolation. The hexapeptide stretch 21DIDLHL26 has been shown to be important in the self-assembly of the Src homology 3 (SH3) domain of p85 subunit of bovine phosphatidylinositol-3-kinase (PI3-SH3). The SH3 domain of chicken brain -spectrin, which is otherwise non-amyloidogenic, is rendered amyloidogenic if 22EVTMKK27 is replaced by DIDLHL. In this article, we describe the aggregation behaviour of DIDLHL-COOH and DIDLHL-CONH2. Our results indicate that DIDLHL-COOH and DIDLHL-CONH2 aggregate to form spherical structures at pH 5 and 6. At pH 5, in the presence of mica, DIDLHL-CONH2 forms short fibrous structures. The presence of NaCl along with mica results in fibrillar structures. At pH 6, DIDLHL-CONH2 forms largely spherical aggregates. Both the peptides are unstructured in solution but adopt -conformation on drying. The aggregates formed by DIDLHL-COOH and DIDLHL-CONH2 are formed during drying process and their structures are modulated by the presence of mica and salt. Our study suggests that a peptide need not have intrinsic amyloidogenic propensity to facilitate the selfassembly of the full-length protein. The propensity of peptides to form self-assembled structures that are non-amyloidogenic could be important in potentiating the self-assembly of full-length proteins into amyloid fibrils.

  3. Effects of beta-amyloid protein on M1 and M2 subtypes of muscarinic acetylcholine receptors in the medial septum-diagonal band complex of the rat: relationship with cholinergic, GABAergic, and calcium-binding protein perikarya.

    Science.gov (United States)

    González, Iván; Arévalo-Serrano, Juan; Sanz-Anquela, José Miguel; Gonzalo-Ruiz, Alicia

    2007-06-01

    Cortical cholinergic dysfunction has been correlated with the expression and processing of beta-amyloid precursor protein. However, it remains unclear as to how cholinergic dysfunction and beta-amyloid (Abeta) formation and deposition might be related to one another. Since the M1- and M2 subtypes of muscarinic acetylcholine receptors (mAChRs) are considered key molecules that transduce the cholinergic message, the purpose of the present study was to assess the effects of the injected Abeta peptide on the number of M1mAchR- and M2mAChR-immunoreactive cells in the medial septum-diagonal band (MS-nDBB) complex of the rat. Injections of Abeta protein into the retrosplenial cortex resulted in a decrease in M1mAChR and M2mAChR immunoreactivity in the MS-nDBB complex. Quantitative analysis revealed a significant reduction in the number of M1mAChR- and M2mAChR-immunoreactive cells in the medial septum nucleus (MS) and in the horizontal nucleus of the diagonal band of Broca (HDB) as compared to the corresponding hemisphere in control animals and with that seen in the contralateral hemisphere, which corresponds to the PBS-injected side. Co-localization studies showed that the M1mAChR protein is localized in GABA-immunoreactive cells of the MS-nDBB complex, in particular those of the MS nucleus, while M2mAChR protein is localized in both the cholinergic and GABAergic cells. Moreover, GABAergic cells containing M2mAChR are mainly localized in the MS nucleus, while cholinergic cells containing M2mAChR are localized in the MS and the HDB nuclei. Our findings suggest that Abeta induces a reduction in M1mAChR- and M2mAChR-containing cells, which may contribute to impairments of cholinergic and GABAergic transmission in the MS-nDBB complex.

  4. Traffic jam at the blood-brain barrier promotes greater accumulation of Alzheimer's disease amyloidproteins in the cerebral vasculature.

    Science.gov (United States)

    Agyare, Edward K; Leonard, Sarah R; Curran, Geoffry L; Yu, Caroline C; Lowe, Val J; Paravastu, Anant K; Poduslo, Joseph F; Kandimalla, Karunya K

    2013-05-06

    Amyloid-β (Aβ) deposition in the brain vasculature results in cerebral amyloid angiopathy (CAA), which occurs in about 80% of Alzheimer's disease (AD) patients. While Aβ42 predominates parenchymal amyloid plaques in AD brain, Aβ40 is prevalent in the cerebrovascular amyloid. Dutch mutation of Aβ40 (E22Q) promotes aggressive cerebrovascular accumulation and leads to severe CAA in the mutation carriers; knowledge of how DutchAβ40 drives this process more efficiently than Aβ40 could reveal various pathophysiological events that promote CAA. In this study we have demonstrated that DutchAβ40 shows preferential accumulation in the blood-brain-barrier (BBB) endothelial cells due to its inefficient blood-to-brain transcytosis. Consequently, DutchAβ40 establishes a permeation barrier in the BBB endothelium, prevents its own clearance from the brain, and promotes the formation of amyloid deposits in the cerebral microvessels. The BBB endothelial accumulation of native Aβ40 is not robust enough to exercise such a significant impact on its brain clearance. Hence, the cerebrovascular accumulation of Aβ40 is slow and may require other copathologies to precipitate into CAA. In conclusion, the magnitude of Aβ accumulation in the BBB endothelial cells is a critical factor that promotes CAA; hence, clearing vascular endothelium of Aβ proteins may halt or even reverse CAA.

  5. A major protein precursor of zebra mussel (Dreissena polymorpha) byssus: deduced sequence and significance.

    Science.gov (United States)

    Anderson, K E; Waite, J H

    1998-04-01

    The zebra mussel is a nonindigenous invader of North American lakes and rivers and one of the few freshwater bivalve molluscs having a byssus--a sclerotized organ used by the mussel for opportunistic attachment to hard surfaces. We have sequenced a foot-specific cDNA whose composite protein sequence was deduced from a series of overlapping but occasionally nonidentical cDNA fragments. The overall deduced sequence matches tryptic peptides from a major byssal precursor protein--Dreissena polymorpha foot protein 1 (Dpfp1). The calculated mass of Dpfp1 is 49 kDa; but this is known to be extensively hydroxylated and O-glycosylated during maturation. Purified native Dpfp1 analyzed using matrix-assisted laser-desorption ionization mass spectrometry with time-of-flight indicates that the protein occurs as at least two size variants with masses of 48.6 and 54.5 kDa. In all probability, the sequence variants reported in this study are related to the larger mass variant. Dpfp1 has a block copolymer-like structure defined by two consensus motifs that are sharply segregated into domains. The N-terminal side of Dpfp1 has 22 tandem repeats of a heptapeptide consensus (P-[V/E]-Y-P-[T/S/delta]-[K/Q]-X); the C-terminal side has 16 repeats of a tridecapeptide motif (K-P-G-P-Y-D-Y-D-G-P-Y-D-K). Both consensus repeats are unique, with some limited homology to other proteins functioning in tension: marine mussel adhesives, plant extensins, titin, and trematode eggshell precursors.

  6. Lipopolysaccharide binding protein and serum amyloid A secretion by human intestinal epithelial cells during the acute phase response.

    Science.gov (United States)

    Vreugdenhil, A C; Dentener, M A; Snoek, A M; Greve, J W; Buurman, W A

    1999-09-01

    The acute phase proteins LPS binding protein (LBP) and serum amyloid A (SAA) are produced by the liver and are present in the circulation. Both proteins have been shown to participate in the immune response to endotoxins. The intestinal mucosa forms a large surface that is continuously exposed to these microbial products. By secretion of antimicrobial and immunomodulating agents, the intestinal epithelium contributes to the defense against bacteria and their products. The aim of this study was to explore the influence of the inflammatory mediators TNF-alpha, IL-6, and IL-1beta on the release of LBP and SAA by intestinal epithelial cells (IEC). In addition, the induction of LBP and SAA release by cell lines of intestinal epithelial cells and hepatic cells was compared. The data obtained show that in addition to liver cells, IEC also expressed LBP mRNA and released bioactive LBP and SAA upon stimulation. Regulation of LBP and SAA release by IEC and hepatocytes was typical for class 1 acute phase proteins, although differences in regulation between the cell types were observed. Endotoxin did not induce LBP and SAA release. Glucocorticoids were demonstrated to strongly enhance the cytokine-induced release of LBP and SAA by IEC, corresponding to hepatocytes. The data from this study, which imply that human IEC can produce LBP and SAA, suggest a role for these proteins in the local defense mechanism of the gut to endotoxin. Furthermore, the results demonstrate that tissues other than the liver are involved in the acute phase response.

  7. Alterations in amyloid beta-protein and apolipoprotein E in cerebrospinal fluid after subarachnoid hemorrhage

    Institute of Scientific and Technical Information of China (English)

    Xinzhong Wen; Yonghong Zhang; Leiming Huo

    2007-01-01

    BACKGROUND: The findings about the alterations in cerebrospinal fluid beta-amyloid protein (Aβ) and apolipoprotein E (ApoE) after subarachnoid hemorrhage indicate that they have significant correlation with prognosis of patients.OBJECTIVE: To observe the alterations in cerebrospinal fluid Aβ and ApoE after subarachnoid hemorrhage (SAH).DESIGN: Contrast observation.SETTING: Department of Neurosurgery, the First Hospital of Lanzhou University.PARTICIPANTS: A total of 25 SAH patients including 16 males and 9 females aged from 13 to 72 years were selected form Department of Neurosurgery, the First Affiliated Hospital of Lanzhou University from October 2003 to February 2004. The Hunt-Hess grade ranged from Ⅰ to Ⅳ, and patients admitted hospital in 24 hours after invasion, affirmed by the brain CT scan and lumbar vertebra puncture, no other severe complications and important organs' functional defect and severe infection, no hematological system disease.METHODS: All admitted patients were collected CSF by lumbar vertebra puncture in 24 hours. The cerebrospinal fluid (CSF) of control group came from the admitted 15 patients of our hospital that have no nervous system disease. Aβ content was detected by enzyme linked immunosorbent assay (ELISA), the kit was provided by the Central Laboratory of the First Hospital of Lanzhou University; ApoE concentration was detected by monoclone enzyme linked immunosorbent assay (ELISA), the kit was provided by the Immunotechnique Research Institute of the Fourth Military Medical University. S100B concentration was detected by enzyme linked immunosorbent assay double antibody sandwich method, the kit was provided by the Physiological Research Room of the Fourth Military Medical University. The data were indicated on Mean±SD and were analyzed by SPSS 10.0 statistical package. All data were handled through test of significance variance analysis, and groups were compared through independent sampler t test. The concentration was

  8. Effects of grape seed-derived polyphenols on amyloid beta-protein self-assembly and cytotoxicity.

    Science.gov (United States)

    Ono, Kenjiro; Condron, Margaret M; Ho, Lap; Wang, Jun; Zhao, Wei; Pasinetti, Giulio M; Teplow, David B

    2008-11-21

    Epidemiological evidence suggests that moderate consumption of red wine reduces the incidence of Alzheimer disease (AD). To study the protective effects of red wine, experiments recently were executed in the Tg2576 mouse model of AD. These studies showed that a commercially available grape seed polyphenolic extract, MegaNatural-AZ (MN), significantly attenuated AD-type cognitive deterioration and reduced cerebral amyloid deposition (Wang, J., Ho, L., Zhao, W., Ono, K., Rosensweig, C., Chen, L., Humala, N., Teplow, D. B., and Pasinetti, G. M. (2008) J. Neurosci. 28, 6388-6392). To elucidate the mechanistic bases for these observations, here we used CD spectroscopy, photo-induced cross-linking of unmodified proteins, thioflavin T fluorescence, size exclusion chromatography, and electron microscopy to examine the effects of MN on the assembly of the two predominant disease-related amyloid beta-protein alloforms, Abeta40 and Abeta42. We also examined the effects of MN on Abeta-induced cytotoxicity by assaying 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide metabolism and lactate dehydrogenase activity in Abeta-treated, differentiated pheochromocytoma (PC12) cells. Initial studies revealed that MN blocked Abeta fibril formation. Subsequent evaluation of the assembly stage specificity of the effect showed that MN was able to inhibit protofibril formation, pre-protofibrillar oligomerization, and initial coil --> alpha-helix/beta-sheet secondary structure transitions. Importantly, MN had protective effects in assays of cytotoxicity in which MN was mixed with Abeta prior to peptide assembly or following assembly and just prior to peptide addition to cells. These data suggest that MN is worthy of consideration as a therapeutic agent for AD.

  9. The Flavivirus Precursor Membrane-Envelope Protein Complex: Structure and Maturation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Long; Lok, Shee-Mei; Yu, I-Mei; Zhang, Ying; Kuhn, Richard J.; Chen, Jue; Rossmann, Michael G. (Purdue)

    2008-09-17

    Many viruses go through a maturation step in the final stages of assembly before being transmitted to another host. The maturation process of flaviviruses is directed by the proteolytic cleavage of the precursor membrane protein (prM), turning inert virus into infectious particles. We have determined the 2.2 angstrom resolution crystal structure of a recombinant protein in which the dengue virus prM is linked to the envelope glycoprotein E. The structure represents the prM-E heterodimer and fits well into the cryo-electron microscopy density of immature virus at neutral pH. The pr peptide {beta}-barrel structure covers the fusion loop in E, preventing fusion with host cell membranes. The structure provides a basis for identifying the stages of its pH-directed conformational metamorphosis during maturation, ending with release of pr when budding from the host.

  10. Genome-wide association study of CSF levels of 59 alzheimer's disease candidate proteins: significant associations with proteins involved in amyloid processing and inflammation.

    Directory of Open Access Journals (Sweden)

    John S K Kauwe

    2014-10-01

    Full Text Available Cerebrospinal fluid (CSF 42 amino acid species of amyloid beta (Aβ42 and tau levels are strongly correlated with the presence of Alzheimer's disease (AD neuropathology including amyloid plaques and neurodegeneration and have been successfully used as endophenotypes for genetic studies of AD. Additional CSF analytes may also serve as useful endophenotypes that capture other aspects of AD pathophysiology. Here we have conducted a genome-wide association study of CSF levels of 59 AD-related analytes. All analytes were measured using the Rules Based Medicine Human DiscoveryMAP Panel, which includes analytes relevant to several disease-related processes. Data from two independently collected and measured datasets, the Knight Alzheimer's Disease Research Center (ADRC and Alzheimer's Disease Neuroimaging Initiative (ADNI, were analyzed separately, and combined results were obtained using meta-analysis. We identified genetic associations with CSF levels of 5 proteins (Angiotensin-converting enzyme (ACE, Chemokine (C-C motif ligand 2 (CCL2, Chemokine (C-C motif ligand 4 (CCL4, Interleukin 6 receptor (IL6R and Matrix metalloproteinase-3 (MMP3 with study-wide significant p-values (p<1.46×10-10 and significant, consistent evidence for association in both the Knight ADRC and the ADNI samples. These proteins are involved in amyloid processing and pro-inflammatory signaling. SNPs associated with ACE, IL6R and MMP3 protein levels are located within the coding regions of the corresponding structural gene. The SNPs associated with CSF levels of CCL4 and CCL2 are located in known chemokine binding proteins. The genetic associations reported here are novel and suggest mechanisms for genetic control of CSF and plasma levels of these disease-related proteins. Significant SNPs in ACE and MMP3 also showed association with AD risk. Our findings suggest that these proteins/pathways may be valuable therapeutic targets for AD. Robust associations in cognitively normal

  11. DSP-PP precursor protein cleavage by tolloid-related-1 protein and by bone morphogenetic protein-1.

    Science.gov (United States)

    Ritchie, Helena H; Yee, Colin T; Tang, Xu-Na; Dong, Zhihong; Fuller, Robert S

    2012-01-01

    Dentin sialoprotein (DSP) and phosphophoryn (PP), acidic proteins critical to dentin mineralization, are translated from a single transcript as a DSP-PP precursor that undergoes specific proteolytic processing to generate DSP and PP. The cleavage mechanism continues to be controversial, in part because of the difficulty of obtaining DSP-PP from mammalian cells and dentin matrix. We have infected Sf9 cells with a recombinant baculovirus to produce large amounts of secreted DSP-PP(240), a variant form of rat DSP-PP. Mass spectrometric analysis shows that DSP-PP(240) secreted by Sf9 cells undergoes specific cleavage at the site predicted from the N-terminal sequence of PP extracted from dentin matrix: SMQG(447)↓D(448)DPN. DSP-PP(240) is cleaved after secretion by a zinc-dependent activity secreted by Sf9 cells, generating DSP(430) and PP(240) products that are stable in the medium. DSP-PP processing activity is constitutively secreted by Sf9 cells, but secretion is diminished 3 days after infection. Using primers corresponding to the highly conserved catalytic domain of Drosophila melanogaster tolloid (a mammalian BMP1 homolog), we isolated a partial cDNA for a Spodopotera frugiperda tolloid-related-1 protein (TLR1) that is 78% identical to Drosophila TLR1 but only 65% identical to Drosophila tolloid. Tlr1 mRNA decreased rapidly in Sf9 cells after baculovirus infection and was undetectable 4d after infection, paralleling the observed decrease in secretion of the DSP-PP(240) processing activity after infection. Human BMP1 is more similar to Sf9 and Drosophila TLR1 than to tolloid, and Sf9 TLR1 is more similar to BMP1 than to other mammalian homologs. Recombinant human BMP1 correctly processed baculovirus-expressed DSP-PP(240) in a dose-dependent manner. Together, these data suggest that the physiologically accurate cleavage of mammalian DSP-PP(240) in the Sf9 cell system represents the action of a conserved processing enzyme and support the proposed role of BMP1 in

  12. DSP-PP precursor protein cleavage by tolloid-related-1 protein and by bone morphogenetic protein-1.

    Directory of Open Access Journals (Sweden)

    Helena H Ritchie

    Full Text Available Dentin sialoprotein (DSP and phosphophoryn (PP, acidic proteins critical to dentin mineralization, are translated from a single transcript as a DSP-PP precursor that undergoes specific proteolytic processing to generate DSP and PP. The cleavage mechanism continues to be controversial, in part because of the difficulty of obtaining DSP-PP from mammalian cells and dentin matrix. We have infected Sf9 cells with a recombinant baculovirus to produce large amounts of secreted DSP-PP(240, a variant form of rat DSP-PP. Mass spectrometric analysis shows that DSP-PP(240 secreted by Sf9 cells undergoes specific cleavage at the site predicted from the N-terminal sequence of PP extracted from dentin matrix: SMQG(447↓D(448DPN. DSP-PP(240 is cleaved after secretion by a zinc-dependent activity secreted by Sf9 cells, generating DSP(430 and PP(240 products that are stable in the medium. DSP-PP processing activity is constitutively secreted by Sf9 cells, but secretion is diminished 3 days after infection. Using primers corresponding to the highly conserved catalytic domain of Drosophila melanogaster tolloid (a mammalian BMP1 homolog, we isolated a partial cDNA for a Spodopotera frugiperda tolloid-related-1 protein (TLR1 that is 78% identical to Drosophila TLR1 but only 65% identical to Drosophila tolloid. Tlr1 mRNA decreased rapidly in Sf9 cells after baculovirus infection and was undetectable 4d after infection, paralleling the observed decrease in secretion of the DSP-PP(240 processing activity after infection. Human BMP1 is more similar to Sf9 and Drosophila TLR1 than to tolloid, and Sf9 TLR1 is more similar to BMP1 than to other mammalian homologs. Recombinant human BMP1 correctly processed baculovirus-expressed DSP-PP(240 in a dose-dependent manner. Together, these data suggest that the physiologically accurate cleavage of mammalian DSP-PP(240 in the Sf9 cell system represents the action of a conserved processing enzyme and support the proposed role of BMP

  13. Mannose-Binding Lectin Binds to Amyloid Protein and Modulates Inflammation

    Directory of Open Access Journals (Sweden)

    Mykol Larvie

    2012-01-01

    Full Text Available Mannose-binding lectin (MBL, a soluble factor of the innate immune system, is a pattern recognition molecule with a number of known ligands, including viruses, bacteria, and molecules from abnormal self tissues. In addition to its role in immunity, MBL also functions in the maintenance of tissue homeostasis. We present evidence here that MBL binds to amyloid β peptides. MBL binding to other known carbohydrate ligands is calcium-dependent and has been attributed to the carbohydrate-recognition domain, a common feature of other C-type lectins. In contrast, we find that the features of MBL binding to Aβ are more similar to the reported binding characteristics of the cysteine-rich domain of the unrelated mannose receptor and therefore may involve the MBL cysteine-rich domain. Differences in MBL ligand binding may contribute to modulation of inflammatory response and may correlate with the function of MBL in processes such as coagulation and tissue homeostasis.

  14. Atomic Resolution Structure of Monomorphic Aβ42 Amyloid Fibrils.

    Science.gov (United States)

    Colvin, Michael T; Silvers, Robert; Ni, Qing Zhe; Can, Thach V; Sergeyev, Ivan; Rosay, Melanie; Donovan, Kevin J; Michael, Brian; Wall, Joseph; Linse, Sara; Griffin, Robert G

    2016-08-03

    Amyloid-β (Aβ) is a 39-42 residue protein produced by the cleavage of the amyloid precursor protein (APP), which subsequently aggregates to form cross-β amyloid fibrils that are a hallmark of Alzheimer's disease (AD). The most prominent forms of Aβ are Aβ1-40 and Aβ1-42, which differ by two amino acids (I and A) at the C-terminus. However, Aβ42 is more neurotoxic and essential to the etiology of AD. Here, we present an atomic resolution structure of a monomorphic form of AβM01-42 amyloid fibrils derived from over 500 (13)C-(13)C, (13)C-(15)N distance and backbone angle structural constraints obtained from high field magic angle spinning NMR spectra. The structure (PDB ID: 5KK3 ) shows that the fibril core consists of a dimer of Aβ42 molecules, each containing four β-strands in a S-shaped amyloid fold, and arranged in a manner that generates two hydrophobic cores that are capped at the end of the chain by a salt bridge. The outer surface of the monomers presents hydrophilic side chains to the solvent. The interface between the monomers of the dimer shows clear contacts between M35 of one molecule and L17 and Q15 of the second. Intermolecular (13)C-(15)N constraints demonstrate that the amyloid fibrils are parallel in register. The RMSD of the backbone structure (Q15-A42) is 0.71 ± 0.12 Å and of all heavy atoms is 1.07 ± 0.08 Å. The structure provides a point of departure for the design of drugs that bind to the fibril surface and therefore interfere with secondary nucleation and for other therapeutic approaches to mitigate Aβ42 aggregation.

  15. Stabilization of native amyloid β-protein oligomers by Copper and Hydrogen peroxide Induced Cross-linking of Unmodified Proteins (CHICUP).

    Science.gov (United States)

    Williams, Thomas L; Serpell, Louise C; Urbanc, Brigita

    2016-03-01

    Oligomeric assemblies are postulated to be proximate neurotoxic species in human diseases associated with aberrant protein aggregation. Their heterogeneous and transient nature makes their structural characterization difficult. Size distributions of oligomers of several amyloidogenic proteins, including amyloid β-protein (Aβ) relevant to Alzheimer's disease (AD), have been previously characterized in vitro by photo-induced cross-linking of unmodified proteins (PICUP) followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Due to non-physiological conditions associated with the PICUP chemistry, Aβ oligomers cross-linked by PICUP may not be representative of in vivo conditions. Here, we examine an alternative Copper and Hydrogen peroxide Induced Cross-linking of Unmodified Proteins (CHICUP), which utilizes naturally occurring divalent copper ions and hydrogen peroxide and does not require photo activation. Our results demonstrate that CHICUP and PICUP applied to the two predominant Aβ alloforms, Aβ40 and Aβ42, result in similar oligomer size distributions. Thioflavin T fluorescence data and atomic force microscopy images demonstrate that both CHICUP and PICUP stabilize Aβ oligomers and attenuate fibril formation. Relative to noncross-linked peptides, CHICUP-treated Aβ40 and Aβ42 cause prolonged disruption to biomimetic lipid vesicles. CHICUP-stabilized Aβ oligomers link the amyloid cascade, metal, and oxidative stress hypotheses of AD into a more comprehensive understanding of the molecular basis of AD pathology. Because copper and hydrogen peroxide are elevated in the AD brain, CHICUP-stabilized Aβ oligomers are biologically relevant and should be further explored as a new therapeutic target.

  16. Amyloid-like fibrils from an 18-residue peptide analogue of a part of the central domain of the B-family of silkmoth chorion proteins.

    Science.gov (United States)

    Iconomidou, V A; Chryssikos, G D; Gionis, V; Vriend, G; Hoenger, A; Hamodrakas, S J

    2001-06-22

    Chorion is the major component of silkmoth eggshell. More than 95% of its dry mass consists of the A and B families of low molecular weight structural proteins, which have remarkable mechanical and chemical properties, and protect the oocyte and the developing embryo from the environment. We present data from negative staining, Congo red binding, X-ray diffraction, Fourier transform-Raman, attenuated total reflectance infrared spectroscopy and modelling studies of a synthetic peptide analogue of a part of the central domain of the B family of silkmoth chorion proteins, indicating that this peptide folds and self-assembles, forming amyloid-like fibrils. These results support further our proposal, based on experimental data from a synthetic peptide analogue of the central domain of the A family of chorion proteins, that silkmoth chorion is a natural, protective amyloid [Iconomidou et al., FEBS Lett. 479 (2000) 141-145].

  17. Monoacylated Cellular Prion Proteins Reduce Amyloid-β-Induced Activation of Cytoplasmic Phospholipase A2 and Synapse Damage

    Directory of Open Access Journals (Sweden)

    Ewan West

    2015-06-01

    Full Text Available Alzheimer’s disease (AD is a progressive neurodegenerative disease characterized by the accumulation of amyloid-β (Aβ and the loss of synapses. Aggregation of the cellular prion protein (PrPC by Aβ oligomers induced synapse damage in cultured neurons. PrPC is attached to membranes via a glycosylphosphatidylinositol (GPI anchor, the composition of which affects protein targeting and cell signaling. Monoacylated PrPC incorporated into neurons bound “natural Aβ”, sequestering Aβ outside lipid rafts and preventing its accumulation at synapses. The presence of monoacylated PrPC reduced the Aβ-induced activation of cytoplasmic phospholipase A2 (cPLA2 and Aβ-induced synapse damage. This protective effect was stimulus specific, as treated neurons remained sensitive to α-synuclein, a protein associated with synapse damage in Parkinson’s disease. In synaptosomes, the aggregation of PrPC by Aβ oligomers triggered the formation of a signaling complex containing the cPLA2.a process, disrupted by monoacylated PrPC. We propose that monoacylated PrPC acts as a molecular sponge, binding Aβ oligomers at the neuronal perikarya without activating cPLA2 or triggering synapse damage.

  18. Probing folding free energy landscape of small proteins through minimalistic models: Folding of HP-36 and -amyloid

    Indian Academy of Sciences (India)

    Arnab Mukherjee; Biman Bagchi

    2003-10-01

    Folding dynamics and energy landscape picture of protein conformations of HP-36 and -amyloid (A) are investigated by extensive Brownian dynamics simulations, where the inter amino acid interactions are given by a minimalistic model (MM) we recently introduced [J. Chem. Phys. 118 4733 (2003)]. In this model, a protein is constructed by taking two atoms for each amino acid. One atom represents the backbone C atom, while the other mimics the whole side chain residue. Sizes and interactions of the side residues are all different and specific to a particular amino acid. The effect of water-mediated folding is mapped into the MM by suitable choice of interaction parameters of the side residues obtained from the amino acid hydropathy scale. A new non-local helix potential is incorporated to generate helices at the appropriate positions in a protein. Simulations have been done by equilibrating the protein at high temperature followed by a sudden quench. The subsequent folding is monitored to observe the dynamics of topological contacts (topo), relative contact order parameter (RCO), and the root mean square deviation (RMSD) from the realprotein native structure. The folded structures of different model proteins (HP-36 and ) resemble their respective real native state rather well. The dynamics of folding shows multistage decay, with an initial hydrophobic collapse followed by a long plateau. Analysis of topo and RCO correlates the late stage folding with rearrangement of the side chain residues, particularly those far apart in the sequence. The long plateau also signifies large entropic free energy barrier near the native state, as predicted from theories of protein folding.

  19. Mitogen-activated protein kinase signaling pathways promote low-density lipoprotein receptor-related protein 1-mediated internalization of beta-amyloid protein in primary cortical neurons.

    Science.gov (United States)

    Yang, Wei-Na; Ma, Kai-Ge; Qian, Yi-Hua; Zhang, Jian-Shui; Feng, Gai-Feng; Shi, Li-Li; Zhang, Zhi-Chao; Liu, Zhao-Hui

    2015-07-01

    Mounting evidence suggests that the pathological hallmarks of Alzheimer's disease (AD) are caused by the intraneuronal accumulation of beta-amyloid protein (Aβ). Reuptake of extracellular Aβ is believed to contribute significantly to the intraneuronal Aβ pool in the early stages of AD. Published reports have claimed that the low-density lipoprotein receptor-related protein 1 (LRP1) mediates Aβ1-42 uptake and lysosomal trafficking in GT1-7 neuronal cells and mouse embryonic fibroblast non-neuronal cells. However, there is no direct evidence supporting the role of LRP1 in Aβ internalization in primary neurons. Our recent study indicated that p38 MAPK and ERK1/2 signaling pathways are involved in regulating α7 nicotinic acetylcholine receptor (α7nAChR)-mediated Aβ1-42 uptake in SH-SY5Y cells. This study was designed to explore the regulation of MAPK signaling pathways on LRP1-mediated Aβ internalization in neurons. We found that extracellular Aβ1-42 oligomers could be internalized into endosomes/lysosomes and mitochondria in cortical neurons. Aβ1-42 and LRP1 were also found co-localized in neurons during Aβ1-42 internalization, and they could form Aβ1-42-LRP1 complex. Knockdown of LRP1 expression significantly decreased neuronal Aβ1-42 internalization. Finally, we identified that p38 MAPK and ERK1/2 signaling pathways regulated the internalization of Aβ1-42 via LRP1. Therefore, these results demonstrated that LRP1, p38 MAPK and ERK1/2 mediated the internalization of Aβ1-42 in neurons and provided evidence that blockade of LRP1 or inhibitions of MAPK signaling pathways might be a potential approach to lowering brain Aβ levels and served a potential therapeutic target for AD.

  20. Association of cardiovascular factors and Alzheimer's disease plasma amyloid-beta protein in subjective memory complainers.

    Science.gov (United States)

    Bates, Kristyn A; Sohrabi, Hamid R; Rodrigues, Mark; Beilby, John; Dhaliwal, Satvinder S; Taddei, Kevin; Criddle, Arthur; Wraith, Megan; Howard, Matthew; Martins, Georgia; Paton, Athena; Mehta, Pankaj; Foster, Jonathan K; Martins, Ian J; Lautenschlager, Nicola T; Mastaglia, Frank L; Laws, Simon M; Gandy, Samuel E; Martins, Ralph N

    2009-01-01

    A strong link is indicated between cardiovascular disease (CVD) and risk for developing Alzheimer's disease (AD), which may be exacerbated by the major AD genetic risk factor apolipoprotein Eepsilon4 (APOEepsilon4). Since subjective memory complaint (SMC) may potentially be an early indicator for cognitive decline, we examined CVD risk factors in a cohort of SMC. As amyloid-beta (Abeta) is considered to play a central role in AD, we hypothesized that the CVD risk profile (increased LDL, reduced HDL, and increased body fat) would be associated with plasma Abeta levels. We explored this in 198 individuals with and without SMC (average age = 63 years). Correlations between Abeta40 and HDL were observed, which were stronger in non-APOEepsilon4 carriers (rho = -0.315, p association between HDL and Abeta, which if demonstrated to be causal has implications for the development of lifestyle interventions and/or novel therapeutics. The relationship between HDL and Abeta and the potential significance of such an association needs to be validated in a larger longitudinal study.

  1. ANTIAMNESIC POTENTIAL OF SOLASODINE AGAINST β-AMYLOID PROTEIN INDUCED AMNESIA IN MICE

    Directory of Open Access Journals (Sweden)

    Desai Alpesh B

    2011-05-01

    Full Text Available Alzheimer’s disease (AD, the most common form of dementia in the elderly population, is characterized by an insidious onset with memory impairment and an inexorable progression of cognitive decline. Nootropic agents are a heterogeneous groups of drugs developed for use in dementia and other cerebral disorders. Nootropics agents are being primarily used to improve memory, mood and behavior. However, the resulting adverse effects associated with these agents have limited their use. Therefore, it is worthwhile to explore the utility of traditional medicines for the treatment of various cognitive disorders. The present study was undertaken to assess the potential of solasodine on β-amyloid induced amnesia in mice. Elevated plus maze (EPM and Morris water maze (MWM was employed to evaluate learning and memory parameters. Piracetam was used as the standard drug. Solasodine (1, 2 and 4 mg/kg, p.o. was screened for claimed potential in mice. Solasodine improved both short term memory and long term memory when assessed on Elevated pluz maze and Morris Water maze respectively. Hence, solasodine might prove to be a useful memory restorative agent in the treatment of dementia seen in the Alzheimer’s disease.

  2. Pro-Inflammatory S100A8 and S100A9 Proteins: Self-Assembly into Multifunctional Native and Amyloid Complexes

    Directory of Open Access Journals (Sweden)

    Ludmilla A. Morozova-Roche

    2012-03-01

    Full Text Available S100A8 and S100A9 are EF-hand Ca2+ binding proteins belonging to the S100 family. They are abundant in cytosol of phagocytes and play critical roles in numerous cellular processes such as motility and danger signaling by interacting and modulating the activity of target proteins. S100A8 and S100A9 expression levels increased in many types of cancer, neurodegenerative disorders, inflammatory and autoimmune diseases and they are implicated in the numerous disease pathologies. The Ca2+ and Zn2+-binding properties of S100A8/A9 have a pivotal influence on their conformation and oligomerization state, including self-assembly into homo- and heterodimers, tetramers and larger oligomers. Here we review how the unique chemical and conformational properties of individual proteins and their structural plasticity at the quaternary level account for S100A8/A9 functional diversity. Additional functional diversification occurs via non-covalent assembly into oligomeric and fibrillar amyloid complexes discovered in the aging prostate and reproduced in vitro. This process is also regulated by Ca2+and Zn2+-binding and effectively competes with the formation of the native complexes. High intrinsic amyloid-forming capacity of S100A8/A9 proteins may lead to their amyloid depositions in numerous ailments characterized by their elevated expression patterns and have additional pathological significance requiring further thorough investigation.

  3. Hemodynamic effects of combined focal cerebral ischemia and amyloid protein toxicity in a rat model: a functional CT study.

    Directory of Open Access Journals (Sweden)

    Jun Yang

    Full Text Available BACKGROUND/OBJECTIVE: Clinical evidence indicates that cerebral ischemia (CI and a pathological factor of Alzheimer's disease, the β-amyloid (Aβ protein, can increase the rate of cognitive impairment in the ageing population. Using the CT Perfusion (CTP functional imaging, we sought to investigate the interaction between CI and the Aβ protein on cerebral hemodynamics. METHODS: A previously established rat model of CI and Aβ was used for the CTP study. Iodinated contrast was given intravenously, while serial CT images of sixteen axial slices were acquired. Cerebral blood flow (CBF and blood volume (CBV parametric maps were co-registered to a rat brain atlas and regions of interest were drawn on the maps. Microvascular alteration was investigated with histopathology. RESULTS: CTP results revealed that ipsilateral striatum of Aβ+CI and CI groups showed significantly lower CBF and CBV than control at the acute phase. Striatal CBF and CBV increased significantly at week 1 in the CI and Aβ+CI groups, but not in the Aβ alone or control group. Histopathology showed that average density of dilated microvessels in the ipsilateral striatum in CI and Aβ+CI groups was significantly higher than control at week 1, indicating this could be associated with hyperperfusion and hypervolemia observed from CTP results. CONCLUSION: These results demonstrate that CTP can quantitatively measure the hemodynamic disturbance on CBF and CBV functional maps in a rat model of CI interacting with Aβ.

  4. Amyloid Beta as a Modulator of Synaptic Plasticity

    OpenAIRE

    Parihar, Mordhwaj S.; Gregory J. Brewer

    2010-01-01

    Alzheimer’s disease is associated with synapse loss, memory dysfunction and pathological accumulation of amyloid beta in plaques. However, an exclusively pathological role for amyloid beta is being challenged by new evidence for an essential function of amyloid beta at the synapse. Amyloid beta protein exists in different assembly states in the central nervous system and plays distinct roles ranging from synapse and memory formation to memory loss and neuronal cell death. Amyloid beta is pres...

  5. The nicotinic alpha7 acetylcholine receptor agonist ssr180711 is unable to activate limbic neurons in mice overexpressing human amyloid-beta1-42

    DEFF Research Database (Denmark)

    Soderman, A.; Spang-Thomsen, Mogens; Hansen, H.

    2008-01-01

    7 nAChR have not been examined. The aim of this study has been to evaluate the efficacy of alpha7 nAChR modulators in transgene mice that overexpress human amyloid precursor protein and accumulate Abeta1-40 and Abeta1-42. In accordance with observations in human Alzheimer tissues, we show here...

  6. Bacoside-A, an anti-amyloid natural substance, inhibits membrane disruption by the amyloidogenic determinant of prion protein through accelerating fibril formation.

    Science.gov (United States)

    Malishev, Ravit; Nandi, Sukhendu; Kolusheva, Sofiya; Shaham-Niv, Shira; Gazit, Ehud; Jelinek, Raz

    2016-09-01

    Bacosides, class of compounds extracted from the Bacopa monniera plant, exhibit interesting therapeutic properties, particularly enhancing cognitive functions and putative anti-amyloid activity. We show that bacoside-A exerted significant effects upon fibrillation and membrane interactions of the amyloidogenic fragment of the prion protein [PrP(106-126)]. Specifically, when co-incubated with PrP(106-126), bacoside-A accelerated fibril formation in the presence of lipid bilayers and in parallel inhibited bilayer interactions of the peptide aggregates formed in solution. These interesting phenomena were studied by spectroscopic and microscopic techniques, which suggest that bacoside A-promoted fibrillation reduced the concentration of membrane-active pre-fibrillar species of the prion fragment. This study suggests that induction of fibril formation and corresponding inhibition of membrane interactions are likely the underlying factors for ameliorating amyloid protein toxicity by bacoside-A.

  7. Automatic segmentation of amyloid plaques in MR images using unsupervised support vector machines.

    Science.gov (United States)

    Iordanescu, Gheorghe; Venkatasubramanian, Palamadai N; Wyrwicz, Alice M

    2012-06-01

    Deposition of the β-amyloid peptide (Aβ) is an important pathological hallmark of Alzheimer's disease (AD). However, reliable quantification of amyloid plaques in both human and animal brains remains a challenge. We present here a novel automatic plaque segmentation algorithm based on the intrinsic MR signal characteristics of plaques. This algorithm identifies plaque candidates in MR data by using watershed transform, which extracts regions with low intensities completely surrounded by higher intensity neighbors. These candidates are classified as plaque or nonplaque by an unsupervised learning method using features derived from the MR data intensity. The algorithm performance is validated by comparison with histology. We also demonstrate the algorithm's ability to detect age-related changes in plaque load ex vivo in amyloid precursor protein (APP) transgenic mice that coexpress five familial AD mutations (5xFAD mice). To our knowledge, this study represents the first quantitative method for characterizing amyloid plaques in MRI data. The proposed method can be used to describe the spatiotemporal progression of amyloid deposition, which is necessary for understanding the evolution of plaque pathology in mouse models of Alzheimer's disease and to evaluate the efficacy of emergent amyloid-targeting therapies in preclinical trials.

  8. Formaldehyde at low concentration induces protein tau into globular amyloid-like aggregates in vitro and in vivo.

    Directory of Open Access Journals (Sweden)

    Chun Lai Nie

    Full Text Available Recent studies have shown that neurodegeneration is closely related to misfolding and aggregation of neuronal tau. Our previous results show that neuronal tau aggregates in formaldehyde solution and that aggregated tau induces apoptosis of SH-SY5Y and hippocampal cells. In the present study, based on atomic force microscopy (AFM observation, we have found that formaldehyde at low concentrations induces tau polymerization whilst acetaldehyde does not. Neuronal tau misfolds and aggregates into globular-like polymers in 0.01-0.1% formaldehyde solutions. Apart from globular-like aggregation, no fibril-like polymerization was observed when the protein was incubated with formaldehyde for 15 days. SDS-PAGE results also exhibit tau polymerizing in the presence of formaldehyde. Under the same experimental conditions, polymerization of bovine serum albumin (BSA or alpha-synuclein was not markedly detected. Kinetic study shows that tau significantly misfolds and polymerizes in 60 minutes in 0.1% formaldehyde solution. However, presence of 10% methanol prevents protein tau from polymerization. This suggests that formaldehyde polymerization is involved in tau aggregation. Such aggregation process is probably linked to the tau's special "worm-like" structure, which leaves the epsilon-amino groups of Lys and thiol groups of Cys exposed to the exterior. Such a structure can easily bond to formaldehyde molecules in vitro and in vivo. Polymerizing of formaldehyde itself results in aggregation of protein tau. Immunocytochemistry and thioflavin S staining of both endogenous and exogenous tau in the presence of formaldehyde at low concentrations in the cell culture have shown that formaldehyde can induce tau into amyloid-like aggregates in vivo during apoptosis. The significant protein tau aggregation induced by formaldehyde and the severe toxicity of the aggregated tau to neural cells may suggest that toxicity of methanol and formaldehyde ingestion is related to

  9. Diagnostic utility and limitations of glutamine synthetase and serum amyloid-associated protein immunohistochemistry in the distinction of focal nodular hyperplasia and inflammatory hepatocellular adenoma.

    Science.gov (United States)

    Joseph, Nancy M; Ferrell, Linda D; Jain, Dhanpat; Torbenson, Michael S; Wu, Tsung-Teh; Yeh, Matthew M; Kakar, Sanjay

    2014-01-01

    Inflammatory hepatocellular adenoma can show overlapping histological features with focal nodular hyperplasia, including inflammation, fibrous stroma, and ductular reaction. Expression of serum amyloid-associated protein in inflammatory hepatocellular adenoma and map-like pattern of glutamine synthetase in focal nodular hyperplasia can be helpful in this distinction, but the pitfalls and limitations of these markers have not been established. Morphology and immunohistochemistry were analyzed in 54 inflammatory hepatocellular adenomas, 40 focal nodular hyperplasia, and 3 indeterminate lesions. Morphological analysis demonstrated that nodularity, fibrous stroma, dystrophic blood vessels, and ductular reaction were more common in focal nodular hyperplasia, while telangiectasia, hemorrhage, and steatosis were more common in inflammatory hepatocellular adenoma, but there was frequent overlap of morphological features. The majority of inflammatory hepatocellular adenomas demonstrated perivascular and/or patchy glutamine synthetase staining (73.6%), while the remaining cases had diffuse (7.5%), negative (3.8%), or patchy pattern of staining (15%) that showed subtle differences from the classic map-like staining pattern and was designated as pseudo map-like staining. Positive staining for serum amyloid-associated protein was seen in the majority of inflammatory hepatocellular adenomas (92.6%) and in the minority of focal nodular hyperplasia (17.5%). The glutamine synthetase staining pattern was map-like in 90% of focal nodular hyperplasia cases, with the remaining 10% of cases showing pseudo map-like staining. Three cases were labeled as indeterminate and showed focal nodular hyperplasia-like morphology but lacked map-like glutamine synthetase staining pattern; these cases demonstrated a patchy pseudo map-like glutamine synthetase pattern along with the expression of serum amyloid-associated protein. Our results highlight the diagnostic errors that can be caused by variant

  10. Hypoxia alters cell cycle regulatory protein expression and induces premature maturation of oligodendrocyte precursor cells.

    Directory of Open Access Journals (Sweden)

    Ravi Shankar Akundi

    Full Text Available BACKGROUND: Periventricular white matter injury (PWMI is a common form of brain injury sustained by preterm infants. A major factor that predisposes to PWMI is hypoxia. Because oligodendrocytes (OLs are responsible for myelination of axons, abnormal OL development or function may affect brain myelination. At present our understanding of the influences of hypoxia on OL development is limited. To examine isolated effects of hypoxia on OLs, we examined the influences of hypoxia on OL development in vitro. METHODOLOGY/FINDINGS: Cultures of oligodendrocyte precursor cells (OPCs were prepared from mixed glial cultures and were 99% pure. OPCs were maintained at 21% O(2 or hypoxia (1% or 4% O(2 for up to 7 days. We observed that 1% O(2 lead to an increase in the proportion of myelin basic protein (MBP-positive OLs after 1 week in culture, and a decrease in the proportion of platelet-derived growth factor receptor alpha (PDGFRalpha-positive cells suggesting premature OL maturation. Increased expression of the cell cycle regulatory proteins p27(Kip1 and phospho-cdc2, which play a role in OL differentiation, was seen as well. CONCLUSIONS: These results show that hypoxia interferes with the normal process of OL differentiation by inducing premature OPC maturation.

  11. α-Hemoglobin-stabilizing Protein: An Effective Marker for Erythroid Precursors in Bone Marrow Biopsy Specimens.

    Science.gov (United States)

    Yu, Hongbo; Pinkus, Jack L; Pinkus, Geraldine S

    2016-01-01

    Accurate analysis of the erythroid lineage is essential in evaluating bone marrow biopsies and can be particularly challenging in settings of dyserythropoiesis. α-Hemoglobin-stabilizing protein (AHSP) is an erythroid-specific chaperone protein and represents a potential specific marker for erythroid elements. This study defines the immunohistochemical profile of AHSP, as compared with an established erythroid marker CD71, in 101 bone marrow biopsies including normal marrows and cases of acute pure erythroid leukemia, acute erythroid/myeloid leukemia, other types of acute myeloid leukemia, myelodysplastic syndrome, chronic myelogenous leukemia, other types of myeloproliferative neoplasm, chronic myelomonocytic leukemia, acute lymphoblastic leukemia, plasma cell neoplasm, and metastatic carcinoma. In acute pure erythroid leukemia, blasts in 7 of 11 cases showed similar reactivity for CD71 and AHSP, whereas less extensive reactivity was observed for AHSP as compared with CD71 in the remaining 4 cases. In normal marrows and other various disorders, reactivity for AHSP was similar to CD71 and was restricted to the erythroid lineage. Mature erythrocytes were negative for AHSP as were myeloblasts, lymphoblasts, nonerythroid hematopoietic marrow elements, plasma cells, and carcinoma cells. AHSP is an effective marker for detection of normal or abnormal erythroid precursors in bone marrow biopsies and is a useful addition to an immunohistochemical panel for assessment of neoplastic cells of possible erythroid derivation.

  12. Overexpression of estrogen receptor beta alleviates the toxic effects of beta-amyloid protein on PC12 cells via non-hormonal ligands

    Institute of Scientific and Technical Information of China (English)

    Hui Wang; Lihui Si; Xiaoxi Li; Weiguo Deng; Haimiao Yang; Yuyan Yang; Yan Fu

    2012-01-01

    After binding to the estrogen receptor, estrogen can alleviate the toxic effects of beta-amyloid protein, and thereby exert a therapeutic effect on Alzheimer's disease patients. Estrogen can increase the incidence of breast carcinoma and endometrial cancer in post-menopausal women, so it is not suitable for clinical treatment of Alzheimer's disease. There is recent evidence that the estrogen receptor can exert its neuroprotective effects without estrogen dependence. Real-time quantitative PCR and flow cytometry results showed that, compared with non-transfected PC12 cells, adenovirus-mediated estrogen receptor β gene-transfected PC12 cells exhibited lower expression of tumor necrosis factor α and interleukin 1β under stimulation with beta-amyloid protein and stronger protection from apoptosis. The Akt-specific inhibitor Abi-2 decreased the anti-inflammatory and anti-apoptotic effects of estrogen receptor β gene-transfection. These findings suggest that overexpression of estrogen receptor β can alleviate the toxic effect of beta-amyloid protein on PC12 cells, without estrogen dependence. The Akt pathway is one of the potential means for the anti-inflammatory and anti-apoptotic effects of the estrogen receptor.

  13. THE OPEP COARSE-GRAINED PROTEIN MODEL: FROM SINGLE MOLECULES, AMYLOID FORMATION, ROLE OF MACROMOLECULAR CROWDING AND HYDRODYNAMICS TO RNA/DNA COMPLEXES

    Science.gov (United States)

    Sterpone, Fabio; Melchionna, Simone; Tuffery, Pierre; Pasquali, Samuela; Mousseau, Normand; Cragnolini, Tristan; Chebaro, Yassmine; Saint-Pierre, Jean-Francois; Kalimeri, Maria; Barducci, Alessandro; Laurin, Yohan; Tek, Alex; Baaden, Marc; Nguyen, Phuong Hoang; Derreumaux, Philippe

    2015-01-01

    The OPEP coarse-grained protein model has been applied to a wide range of applications since its first release 15 years ago. The model, which combines energetic and structural accuracy and chemical specificity, allows studying single protein properties, DNA/RNA complexes, amyloid fibril formation and protein suspensions in a crowded environment. Here we first review the current state of the model and the most exciting applications using advanced conformational sampling methods. We then present the current limitations and a perspective on the on-going developments. PMID:24759934

  14. Binding of complement proteins C1q and C4bp to serum amyloid P component (SAP) in solid contra liquid phase

    DEFF Research Database (Denmark)

    Sørensen, Inge Juul; Nielsen, EH; Andersen, Ove;

    1996-01-01

    Serum amyloid P component (SAP), a member of the conserved pentraxin family of plasma proteins, binds calcium dependently to its ligands. The authors investigated SAPs interaction with the complement proteins C4b binding protein (C4bp) and C1q by ELISA, immunoelectrophoresis and electron microscopy...... affinity, did not interfere with the subsequent binding of C4bp or C1q to SAP. In contrast, collagen I and IV showed partial competition with the binding of C1q to SAP. Using fresh serum, immobilized native SAP bound C4bp whereas binding of C1q/C1 could not be demonstrated. Altogether the results indicate...

  15. Data supporting beta-amyloid dimer structural transitions and protein–lipid interactions on asymmetric lipid bilayer surfaces using MD simulations on experimentally derived NMR protein structures

    Directory of Open Access Journals (Sweden)

    Sara Y. Cheng

    2016-06-01

    Full Text Available This data article supports the research article entitled “Maximally Asymmetric Transbilayer Distribution of Anionic Lipids Alters the Structure and interaction with Lipids of an Amyloidogenic Protein Dimer Bound to the Membrane Surface” [1]. We describe supporting data on the binding kinetics, time evolution of secondary structure, and residue-contact maps of a surface-absorbed beta-amyloid dimer protein on different membrane surfaces. We further demonstrate the sorting of annular and non-annular regions of the protein/lipid bilayer simulation systems, and the correlation of lipid-number mismatch and surface area per lipid mismatch of asymmetric lipid membranes.

  16. Traditional Chinese Nootropic Medicine Radix Polygalae and Its Active Constituent Onjisaponin B Reduce β-Amyloid Production and Improve Cognitive Impairments.

    Science.gov (United States)

    Li, Xiaohang; Cui, Jin; Yu, Yang; Li, Wei; Hou, Yujun; Wang, Xin; Qin, Dapeng; Zhao, Cun; Yao, Xinsheng; Zhao, Jian; Pei, Gang

    2016-01-01

    Decline of cognitive function is the hallmark of Alzheimer's disease (AD), regardless of the pathological mechanism. Traditional Chinese medicine has been used to combat cognitive impairments and has been shown to improve learning and memory. Radix Polygalae (RAPO) is a typical and widely used herbal medicine. In this study, we aimed to follow the β-amyloid (Aβ) reduction activity to identify active constituent(s) of RAPO. We found that Onjisaponin B of RAPO functioned as RAPO to suppress Aβ production without direct inhibition of β-site amyloid precursor protein cleaving enzyme 1 (BACE1) and γ-secretase activities. Our mechanistic study showed that Onjisaponin B promoted the degradation of amyloid precursor protein (APP). Further, oral administration of Onjisaponin B ameliorated Aβ pathology and behavioral defects in APP/PS1 mice. Taken together, our results indicate that Onjisaponin B is effective against AD, providing a new therapeutic agent for further drug discovery.

  17. Traditional Chinese Nootropic Medicine Radix Polygalae and Its Active Constituent Onjisaponin B Reduce β-Amyloid Production and Improve Cognitive Impairments.

    Directory of Open Access Journals (Sweden)

    Xiaohang Li

    Full Text Available Decline of cognitive function is the hallmark of Alzheimer's disease (AD, regardless of the pathological mechanism. Traditional Chinese medicine has been used to combat cognitive impairments and has been shown to improve learning and memory. Radix Polygalae (RAPO is a typical and widely used herbal medicine. In this study, we aimed to follow the β-amyloid (Aβ reduction activity to identify active constituent(s of RAPO. We found that Onjisaponin B of RAPO functioned as RAPO to suppress Aβ production without direct inhibition of β-site amyloid precursor protein cleaving enzyme 1 (BACE1 and γ-secretase activities. Our mechanistic study showed that Onjisaponin B promoted the degradation of amyloid precursor protein (APP. Further, oral administration of Onjisaponin B ameliorated Aβ pathology and behavioral defects in APP/PS1 mice. Taken together, our results indicate that Onjisaponin B is effective against AD, providing a new therapeutic agent for further drug discovery.

  18. Human serum amyloid A3 (SAA3 protein, expressed as a fusion protein with SAA2, binds the oxidized low density lipoprotein receptor.

    Directory of Open Access Journals (Sweden)

    Takeshi Tomita

    Full Text Available Serum amyloid A3 (SAA3 possesses characteristics distinct from the other serum amyloid A isoforms, SAA1, SAA2, and SAA4. High density lipoprotein contains the latter three isoforms, but not SAA3. The expression of mouse SAA3 (mSAA3 is known to be up-regulated extrahepatically in inflammatory responses, and acts as an endogenous ligand for the toll-like receptor 4/MD-2 complex. We previously reported that mSAA3 plays an important role in facilitating tumor metastasis by attracting circulating tumor cells and enhancing hyperpermeability in the lungs. On the other hand, human SAA3 (hSAA3 has long been regarded as a pseudogene, which is in contrast to the abundant expression levels of the other isoforms. Although the nucleotide sequence of hSAA3 is very similar to that of the other SAAs, a single oligonucleotide insertion in exon 2 causes a frame-shift to generate a unique amino acid sequence. In the present study, we identified that hSAA3 was transcribed in the hSAA2-SAA3 fusion transcripts of several human cell lines. In the fusion transcript, hSAA2 exon 3 was connected to hSAA3 exon 1 or hSAA3 exon 2, located approximately 130kb downstream from hSAA2 exon 3 in the genome, which suggested that it is produced by alternative splicing. Furthermore, we succeeded in detecting and isolating hSAA3 protein for the first time by an immunoprecipitation-enzyme linked immune assay system using monoclonal and polyclonal antibodies that recognize the hSAA3 unique amino acid sequence. We also demonstrated that hSAA3 bound oxidized low density lipoprotein receptor (oxLDL receptor, LOX-1 and elevated the phosphorylation of ERK, the intracellular MAP-kinase signaling protein.

  19. Ilex latifolia Prevents Amyloid β Protein (25-35)-Induced Memory Impairment by Inhibiting Apoptosis and Tau Phosphorylation in Mice.

    Science.gov (United States)

    Kim, Joo Youn; Lee, Hong Kyu; Jang, Ji Yeon; Yoo, Jae Kuk; Seong, Yeon Hee

    2015-12-01

    Ilex latifolia Thunb. (Aquifoliaceae), a Chinese bitter tea called "kudingcha," has been widely consumed as a health beverage and found to possess antioxidant, antidiabetic, antihypertensive, anti-inflammatory, and anti-ischemic activities. The aim of the present study was to investigate the neuroprotective effects of an ethanol extract of I. latifolia against amyloid β protein (Aβ)-induced memory impairment in mice and neurotoxicity in cultured rat cortical neurons. Memory impairment in mice was induced by intracerebroventricular injection of 15 nmol Aβ (25-35) and measured by the passive avoidance test and Morris water maze test. Chronic administration of I. latifolia (25-100 mg/kg, p.o.) significantly prevented Aβ (25-35)-induced memory loss. I. latifolia also prevented the decrease of glutathione concentrations, increased lipid peroxidation, expression of phosphorylated tau (p-tau), and changes in apoptosis-associated proteins in the memory-impaired mouse brain. Exposure of cultured cortical neurons to 10 μM Aβ (25-35) for 36 h induced neuronal apoptotic death. The neuronal cell death, elevation of intracellular Ca(2+) concentration, generation of reactive oxygen species, and expression of proapoptotic proteins caused by Aβ (25-35) in the cultured neurons were inhibited by treatment with I. latifolia (1-50 μg/mL). These results suggest that I. latifolia may have a possible therapeutic role in managing cognitive impairment associated with Alzheimer's disease. The underlying mechanism might involve the antiapoptotic effects mediated by antioxidant activity and inhibition of p-tau formation.

  20. Expression of feline immunodeficiency virus gag and env precursor proteins in Spodoptera frugiperda cells and their use in immunodiagnosis

    NARCIS (Netherlands)

    Horzinek, M.C.; Verschoor, E.J.; Vliet, A.L.W. van; Egberink, H.F.; Hesselink, W.; Ronde, A. de

    1993-01-01

    The gag and env genes of the feline immunodeficiency virus strain UT113 were cloned into a baculovirus transfer vector. The recombinant plasmids were used to create recombinant baculoviruses that expressed either the gag or the env precursor protein in insect cells (Sf9 cells). Leader sequence cleav

  1. Targeting amyloid-degrading enzymes as therapeutic strategies in neurodegeneration.

    Science.gov (United States)

    Turner, Anthony J; Fisk, Lilia; Nalivaeva, Natalia N

    2004-12-01

    The levels of amyloid beta-peptides (Abeta) in the brain represent a dynamic equilibrium state as a result of their biosynthesis from the amyloid precursor protein (APP) by beta- and gamma-secretases, their degradation by a team of amyloid-degrading enzymes, their subsequent oligomerization, and deposition into senile plaques. While most therapeutic attention has focused on developing inhibitors of secretases to prevent Abeta formation, enhancing the rate of Abeta degradation represents an alternative and viable strategy. Current evidence both in vivo and in vitro suggests that there are three major players in amyloid turnover: neprilysin, endothelin converting enzyme(s), and insulin-degrading enzyme, all of which are zinc metallopeptidases. Other proteases have also been implicated in amyloid metabolism, including angiotensin-converting enzyme, and plasmin but for these the evidence is less compelling. Neprilysin and endothelin converting enzyme(s) are homologous membrane proteins of the M13 peptidase family, which normally play roles in the biosynthesis and/or metabolism of regulatory peptides. Insulin-degrading enzyme is structurally and mechanistically distinct. The regional, cellular, and subcellular localizations of these enzymes differ, providing an efficient and diverse mechanism for protecting the brain against the normal accumulation of toxic Abeta peptides. Reduction in expression levels of some of these proteases following insults (e.g., hypoxia and ischemia) or aging might predispose to the development of Alzheimer's disease. Conversely, enhancement of their levels by gene delivery or pharmacological means could be neuroprotective. Even a relatively small enhancement of Abeta metabolism could slow the inexorable progression of the disease. The relative merits of targeting these enzymes for the treatment of Alzheimer's disease will be reviewed and possible side-effects of enhancing their activity evaluated.

  2. Thrombus precursor protein for monitoring anticoagulation in patients with mechanical valve prosthesis

    Institute of Scientific and Technical Information of China (English)

    Qin Chuan; Xiao Yingbin

    2009-01-01

    Objective: To evaluate the plasma concentration of thrombus precursor protein (TPP) in patients after mechanical heart valve replacement, and to explore whether it can be used as a marker for monitoring anticoagulation. Methods: Totally 60 patients who took warfarin after mitral valve replacement and 20 control patients with non-valvular heart diseases were subjected in this study. Their plasma TPP concentration and international normalized ratio (INR) were determined, and compared not only between the anticoagulant patients and the control patients, but also between the patients with atrial fibrillaiton (AF, n=37) and the patients with sinus rhythm (SR, n=23) after mechanical valve replacement. The relationship between plasma TPP concentration and INR in the 60 anticoagulant patients was analyzed with linear regression. Results: It was found that the anticoagulant therapy effectively decreased plasma TPP concentration and elevated INR. In the anticoagulant group, the patients with AF had higher plasma TPP concentration than the others with sinus rhythm (P0.05). No significant correlation was found between plasma TPP concentration and INR in the anticoagulant patients (P>0.05). INR did not accord with plasma TPP concentration in several patients. Conclusion: INR can't reflect the coagulation status and guide the anticoagulation correctly sometimes; TPP may be a valuable assistant marker for monitoring anticoagulation in patients with mechanical heart valve prothesis; Patients with AF may require higher density of anticoagulation and TPP is strongly suggested to be monitored in these patients.

  3. Protein: MPA4 [TP Atlas

    Lifescience Database Archive (English)

    Full Text Available MPA4 γ-secretase Bace1 Bace Beta-secretase 1 Aspartyl protease 2, Beta-site amyloid precursor prot...ein cleaving enzyme 1, Memapsin-2, Membrane-associated aspartic protease 2 10090 Mus musculus 23821 P56818 23821 P56818 21543615 ...

  4. Protein: MPA4 [TP Atlas

    Lifescience Database Archive (English)

    Full Text Available MPA4 γ-secretase BACE1 BACE, KIAA1149 BACE1 Beta-secretase 1 Aspartyl protease 2, B...eta-site amyloid precursor protein cleaving enzyme 1, Memapsin-2, Membrane-associated aspartic protease 2 96

  5. The mechanism of amyloid-fibril formation by stefin B: temperature and protein concentration dependence of the rates.

    Science.gov (United States)

    Skerget, Katja; Vilfan, Andrej; Pompe-Novak, Marusa; Turk, Vito; Waltho, Jonathan P; Turk, Dusan; Zerovnik, Eva

    2009-02-01

    Cystatins, a family of structurally related cysteine proteinase inhibitors, have proved to be useful model system to study amyloidogenesis. We have extended previous studies of the kinetics of amyloid-fibril formation by human stefin B (cystatin B) and some of its mutants, and proposed an improved model for the reaction. Overall, the observed kinetics follow the nucleation and growth behavior observed for many other amyloidogenic proteins. The minimal kinetic scheme that best fits measurements of changes in CD and thioflavin T fluorescence as a function of protein concentration and temperature includes nucleation (modeled as N(I) irreversible transitions with equivalent rates (k(I)), which fitted with N(I) = 64), fibril growth and nonproductive oligomerization, best explained by an off-pathway state with a rate-limiting escape rate. Three energies of activation were derived from global fitting to the minimal kinetic scheme, and independently through the fitting of the individual component rates. Nucleation was found to be a first-order process within an oligomeric species with an enthalpy of activation of 55 +/- 4 kcal mol(-1). Fibril growth was a second-order process with an enthalpy of activation (27 +/- 5 kcal mol(-1)), which is indistinguishable from that of tetramer formation by cystatins, which involves limited conformational changes including proline trans to cis isomerization. The highest enthalpy of activation (95 +/- 5 kcal mol(-1) at 35 degrees C), characteristic of a substantial degree of unfolding as observed prior to domain-swapping reactions, equated with the escape rate of the off-pathway oligomeric state.

  6. Amyloid-related biomarkers and axonal damage proteins in parkinsonian syndromes

    DEFF Research Database (Denmark)

    Bech, Sara; Hjermind, Lena E; Salvesen, Lisette;

    2012-01-01

    Clinical differentiation between parkinsonian syndromes (PS) remains a challenge despite well-established clinical diagnostic criteria. Specific diagnostic biomarkers have yet to be identified, though in recent years, studies have been published on the aid of certain brain related proteins (BRP...

  7. Deposition of kappa and lambda light chains in amyloid filaments of dialysis-related amyloidosis.

    Science.gov (United States)

    Brancaccio, D; Ghiggeri, G M; Braidotti, P; Garberi, A; Gallieni, M; Bellotti, V; Zoni, U; Gusmano, R; Coggi, G

    1995-10-01

    beta 2-Microglobulin (beta 2m) is considered to be the amyloidogenic precursor in dialysis-related amyloidosis, although the implication of other relevant cofactors in the pathogenesis of this disease has also been hypothesized. It is conceivable that substances found in amyloid deposits might represent something more than simple codeposition, possibly playing a pathogenic role in amyloidogenesis. Along these lines, a detailed analysis of the protein composition of amyloid fibrils purified from synovial material surgically obtained from nine patients on long-term dialysis was carried out. By the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, several other protein components, in addition to beta 2m, were found. These were characterized by NH2 amino-terminal sequencing and immunoblotting. In fibrils obtained by water extraction, which fulfill the electron microscopy criteria of highly pure amyloid material, polyclonal kappa and lambda light chains were detected with a concentration of 15 micrograms/mL in the water extraction material; the beta 2m concentration was 200 micrograms/mL. Light microscopy immunohistochemistry was performed on samples from five patients. Amyloid deposits reacted with anti-beta 2m, and anti-light (kappa, lambda), chain antibodies. The immunoreaction of amyloid filaments to anti-beta 2m, anti-lambda, and anti-kappa light chain antibodies was also tested by electron microscopy by use of the immunogold staining procedure. Amyloid filaments were labeled by the three antibodies and showed a different intensity of immunostaining apparently related to their different aggregation pattern. These observations demonstrate that polyclonal immunoglobulin light chains (kappa and lambda) are not contaminants but, together with beta 2m, represent a major constituent of amyloid deposits in dialysis-related osteoarticular amyloidosis, thus indicating their possible role in amyloidogenesis.

  8. Viral precursor protein P3 and its processed products perform discrete and essential functions in the poliovirus RNA replication complex.

    Science.gov (United States)

    Spear, Allyn; Ogram, Sushma A; Morasco, B Joan; Smerage, Lucia Eisner; Flanegan, James B

    2015-11-01

    The differential use of protein precursors and their products is a key strategy used during poliovirus replication. To characterize the role of protein precursors during replication, we examined the complementation profiles of mutants that inhibited 3D polymerase or 3C-RNA binding activity. We showed that 3D entered the replication complex in the form of its precursor, P3 (or 3CD), and was cleaved to release active 3D polymerase. Furthermore, our results showed that P3 is the preferred precursor that binds to the 5'CL. Using reciprocal complementation assays, we showed that one molecule of P3 binds the 5'CL and that a second molecule of P3 provides 3D. In addition, we showed that a second molecule of P3 served as the VPg provider. These results support a model in which P3 binds to the 5'CL and recruits additional molecules of P3, which are cleaved to release either 3D or VPg to initiate RNA replication.

  9. The Formation of Fibrils by Intertwining of Filaments: Model and Application to AmyloidProtein

    Science.gov (United States)

    van Gestel, Jeroen; de Leeuw, Simon W.

    2007-01-01

    We outline a model that describes the interaction of rods that form intertwined bundles. In this simple model, we compare the elastic energy penalty that arises due to the deformation of the rods to the gain in binding energy upon intertwining. We find that, for proper values of the bending Young's modulus and the binding energy, a helical pitch may be found for which the energy of intertwining is most favorable. We apply our description to the problem of Alzheimer's Aβ protein fibrillization. If we forbid configurations that exhibit steric overlap between the protofilaments that make up a protein fibril, our model predicts that fibrils consisting of three protofilaments shall form. This agrees well with experimental results. Our model can also provide an estimate for the helical pitch of suitable fibrils. PMID:17114229

  10. Ionic self-complementarity induces amyloid-like fibril formation in an isolated domain of a plant copper metallochaperone protein

    Directory of Open Access Journals (Sweden)

    Salom David

    2004-06-01

    Full Text Available Abstract Background Arabidopsis thaliana copper metallochaperone CCH is a functional homologue of yeast antioxidant ATX1, involved in cytosolic copper transport. In higher plants, CCH has to be transported to specialised cells through plasmodesmata, being the only metallochaperone reported to date that leaves the cell where it is synthesised. CCH has two different domains, the N-terminal domain conserved among other copper-metallochaperones and a C-terminal domain absent in all the identified non-plant metallochaperones. The aim of the present study was the biochemical and biophysical characterisation of the C-terminal domain of the copper metallochaperone CCH. Results The conformational behaviour of the isolated C-domain in solution is complex and implies the adoption of mixed conformations in different environments. The ionic self-complementary peptide KTEAETKTEAKVDAKADVE, derived from the C-domain of CCH, adopts and extended conformation in solution with a high content in β-sheet structure that induces a pH-dependent fibril formation. Freeze drying electron microscopy studies revealed the existence of well ordered amyloid-like fibrils in preparations from both the C-domain and its derivative peptide. Conclusion A number of proteins related with copper homeostasis have a high tendency to form fibrils. The determinants for fibril formation, as well as the possible physiological role are not fully understood. Here we show that the plant exclusive C-domain of the copper metallochaperone CCH has conformational plasticity and forms fibrils at defined experimental conditions. The putative influence of these properties with plant copper delivery will be addressed in the future.

  11. Amyloid β-protein differentially affects NMDA receptor- and GABAA receptor-mediated currents in rat hippocampal CA1 neurons

    Institute of Scientific and Technical Information of China (English)

    Junfang Zhang; Lei Hou; Xiuping Gao; Fen Guo; Wei Jing; Jinshun Qi; Jiantian Qiao

    2009-01-01

    Although the aggregated amyloid β-protein (Aβ) in senile plaques is one of the key neuropathological features of Alzheimer's disease (AD), soluble forms of Aβ also interfere with synaptic plasticity at the early stage of AD. The suppressive action of acute application of Aβ on hippocampal long-term potentiation (LTP) has been reported widely, whereas the mechanism underlying the effects of Aβ is still mostly unknown. The present study, using the whole-cell patch clamp technique, investigated the effects of Aβ fragments (Aβ25-35 and Aβ31-35) on the LTP induction-related postsynaptic ligand-gated channel currents in isolated hippocampal CA1 neurons. The results showed a rapid but opposite action of both peptides on excitatory and inhibitory receptor currents. Glutamate application-induced currents were suppressed by A β25-35 in a dose-dependent manner, and further N-methyl-I>aspartate (NMDA) receptor-mediated currents were selec-tively inhibited. In contrast, pretreatment with Aβ fragments potentiated γ-aminobutyric acid (GABA)-induced whole-cell currents. As a control, Aβ35-31 the reversed sequence of Aβ35-31 showed no effect on the currents induced by glutamate, NMDA or GABA. These results may partly explain the impaired effects of Aβ on hippocampal LTP, and suggest that the functional down-regulation of N M DA receptors and up-regulation of GABAA receptors may play an important role in remodeling the hippocampal synaptic plasticity in early AD.

  12. PB1-F2 influenza A virus protein adopts a beta-sheet conformation and forms amyloid fibers in membrane environments.

    Science.gov (United States)

    Chevalier, Christophe; Al Bazzal, Ali; Vidic, Jasmina; Février, Vincent; Bourdieu, Christiane; Bouguyon, Edwige; Le Goffic, Ronan; Vautherot, Jean-François; Bernard, Julie; Moudjou, Mohammed; Noinville, Sylvie; Chich, Jean-François; Da Costa, Bruno; Rezaei, Human; Delmas, Bernard

    2010-04-23

    The influenza A virus PB1-F2 protein, encoded by an alternative reading frame in the PB1 polymerase gene, displays a high sequence polymorphism and is reported to contribute to viral pathogenesis in a sequence-specific manner. To gain insights into the functions of PB1-F2, the molecular structure of several PB1-F2 variants produced in Escherichia coli was investigated in different environments. Circular dichroism spectroscopy shows that all variants have a random coil secondary structure in aqueous solution. When incubated in trifluoroethanol polar solvent, all PB1-F2 variants adopt an alpha-helix-rich structure, whereas incubated in acetonitrile, a solvent of medium polarity mimicking the membrane environment, they display beta-sheet secondary structures. Incubated with asolectin liposomes and SDS micelles, PB1-F2 variants also acquire a beta-sheet structure. Dynamic light scattering revealed that the presence of beta-sheets is correlated with an oligomerization/aggregation of PB1-F2. Electron microscopy showed that PB1-F2 forms amorphous aggregates in acetonitrile. In contrast, at low concentrations of SDS, PB1-F2 variants exhibited various abilities to form fibers that were evidenced as amyloid fibers in a thioflavin T assay. Using a recombinant virus and its PB1-F2 knock-out mutant, we show that PB1-F2 also forms amyloid structures in infected cells. Functional membrane permeabilization assays revealed that the PB1-F2 variants can perforate membranes at nanomolar concentrations but with activities found to be sequence-dependent and not obviously correlated with their differential ability to form amyloid fibers. All of these observations suggest that PB1-F2 could be involved in physiological processes through different pathways, permeabilization of cellular membranes, and amyloid fiber formation.

  13. PB1-F2 Influenza A Virus Protein Adopts a β-Sheet Conformation and Forms Amyloid Fibers in Membrane Environments

    Science.gov (United States)

    Chevalier, Christophe; Al Bazzal, Ali; Vidic, Jasmina; Février, Vincent; Bourdieu, Christiane; Bouguyon, Edwige; Le Goffic, Ronan; Vautherot, Jean-François; Bernard, Julie; Moudjou, Mohammed; Noinville, Sylvie; Chich, Jean-François; Da Costa, Bruno; Rezaei, Human; Delmas, Bernard

    2010-01-01

    The influenza A virus PB1-F2 protein, encoded by an alternative reading frame in the PB1 polymerase gene, displays a high sequence polymorphism and is reported to contribute to viral pathogenesis in a sequence-specific manner. To gain insights into the functions of PB1-F2, the molecular structure of several PB1-F2 variants produced in Escherichia coli was investigated in different environments. Circular dichroism spectroscopy shows that all variants have a random coil secondary structure in aqueous solution. When incubated in trifluoroethanol polar solvent, all PB1-F2 variants adopt an α-helix-rich structure, whereas incubated in acetonitrile, a solvent of medium polarity mimicking the membrane environment, they display β-sheet secondary structures. Incubated with asolectin liposomes and SDS micelles, PB1-F2 variants also acquire a β-sheet structure. Dynamic light scattering revealed that the presence of β-sheets is correlated with an oligomerization/aggregation of PB1-F2. Electron microscopy showed that PB1-F2 forms amorphous aggregates in acetonitrile. In contrast, at low concentrations of SDS, PB1-F2 variants exhibited various abilities to form fibers that were evidenced as amyloid fibers in a thioflavin T assay. Using a recombinant virus and its PB1-F2 knock-out mutant, we show that PB1-F2 also forms amyloid structures in infected cells. Functional membrane permeabilization assays revealed that the PB1-F2 variants can perforate membranes at nanomolar concentrations but with activities found to be sequence-dependent and not obviously correlated with their differential ability to form amyloid fibers. All of these observations suggest that PB1-F2 could be involved in physiological processes through different pathways, permeabilization of cellular membranes, and amyloid fiber formation. PMID:20172856

  14. Amyloid and tau cerebrospinal fluid biomarkers in HIV infection

    Directory of Open Access Journals (Sweden)

    Rosengren Lars

    2009-12-01

    Full Text Available Abstract Background Because of the emerging intersections of HIV infection and Alzheimer's disease, we examined cerebrospinal fluid (CSF biomarkers related of amyloid and tau metabolism in HIV-infected patients. Methods In this cross-sectional study we measured soluble amyloid precursor proteins alpha and beta (sAPPα and sAPPβ, amyloid beta fragment 1-42 (Aβ1-42, and total and hyperphosphorylated tau (t-tau and p-tau in CSF of 86 HIV-infected (HIV+ subjects, including 21 with AIDS dementia complex (ADC, 25 with central nervous system (CNS opportunistic infections and 40 without neurological symptoms and signs. We also measured these CSF biomarkers in 64 uninfected (HIV- subjects, including 21 with Alzheimer's disease, and both younger and older controls without neurological disease. Results CSF sAPPα and sAPPβ concentrations were highly correlated and reduced in patients with ADC and opportunistic infections compared to the other groups. The opportunistic infection group but not the ADC patients had lower CSF Aβ1-42 in comparison to the other HIV+ subjects. CSF t-tau levels were high in some ADC patients, but did not differ significantly from the HIV+ neuroasymptomatic group, while CSF p-tau was not increased in any of the HIV+ groups. Together, CSF amyloid and tau markers segregated the ADC patients from both HIV+ and HIV- neuroasymptomatics and from Alzheimer's disease patients, but not from those with opportunistic infections. Conclusions Parallel reductions of CSF sAPPα and sAPPβ in ADC and CNS opportunistic infections suggest an effect of CNS immune activation or inflammation on neuronal amyloid synthesis or processing. Elevation of CSF t-tau in some ADC and CNS infection patients without concomitant increase in p-tau indicates neural injury without preferential accumulation of hyperphosphorylated tau as found in Alzheimer's disease. These biomarker changes define pathogenetic pathways to brain injury in ADC that differ from those

  15. Promotion of formation of amyloid fibrils by aluminium adenosine triphosphate (AlATP).

    Science.gov (United States)

    Exley, C; Korchazhkina, O V

    2001-04-01

    The formation of amyloid fibrils is considered to be an important step in the aetiology of Alzheimer's disease and other amyloidoses. Fibril formation in vitro has been shown to depend on many different factors including modifications to the amino acid profile of fibrillogenic peptides and interactions with both large and small molecules of physiological significance. How these factors might contribute to amyloid fibril formation in vivo is not clear as very little is known about the promotion of fibril formation in undersaturated solutions of amyloidogenic peptides. We have used thioflavin T fluorescence and reverse phase high performance liquid chromatography to show that ATP, and in particular AlATP, promoted the formation of thioflavin T-reactive fibrils of beta amyloid and, an unrelated amyloidogenic peptide, amylin. Evidence is presented that induction of fibril formation followed the complexation of AIATP by one or more monomers of the respective peptide. However, the complex formed could not be identified directly and it is suggested that AlATP might be acting as a chaperone in the assembly of amyloid fibrils. The effect of AlATP was not mimicked by either AlADP or AlAMP. However, it was blocked by suramin, a P2 ATP receptor antagonist, and this has prompted us to speculate that the precursor proteins to beta amyloid and amylin may be substrates or receptors for ATP in vivo.

  16. Amyloid β Protein Aggravates Neuronal Senescence and Cognitive Deficits in 5XFAD Mouse Model of Alzheimer's Disease

    Institute of Scientific and Technical Information of China (English)

    Zhen Wei; Xiao-Chun Chen; Yue Song; Xiao-Dong Pan; Xiao-Man Dai; Jing Zhang; Xiao-Li Cui

    2016-01-01

    Background:Amyloid β (Aβ) has been established as a key factor for the pathological changes in the brains of patients with Alzheimer's disease (AD),and cellular senescence is closely associated with aging and cognitive impairment.However,it remains blurred whether,in the AD brains,Aβ accelerates the neuronal.senescence and whether this senescence,in turn,impairs the cognitive function.This study aimed to explore the expression of senescence-associated genes in the hippocampal tissue from young to aged 5XFAD mice and their age-matched wild type (WT) mice to determine whether senescent neurons are present in the transgenic AD mouse model.Methods:The 5XFAD mice and age-matched wild type mice,both raised from 1 to 18 months,were enrolled in the study.The senescence-associated genes in the hippocampus were analyzed and differentially expressed genes (DEGs) were screened by quantitative real-time polymerase chain reaction.Cognitive performance of the mice was evaluated by Y-maze and Morris water maze tests.Oligomeric Aβ (oAβ) (1-42) was applied to culture primary neurons to simulate the in vivo manifestation.Aging-related proteins were detected by Western blotting analysis and immunofluorescence.Results:In 5XFAD mice,of all the DEGs,the senescence-associated marker p 16 was most significantly increased,even at the early age.It was mainly localized in neurons,with a marginal expression in astrocytes (labeled as glutamine synthetase),nil expression in activated microglia (labeled as Iba1),and negatively correlated with the spatial cognitive impairments of 5XFAD mice.oAβ (1-42) induced the production of senescence-related protein p 16,but not p53 in vitro,which was in line with the in vivo manifestation.Conclusions:oAβ-accelerated neuronal senescence may be associated with the cognitive impairment in 5XFAD mice.Senescence-associated marker p 16 can serve as an indicator to estimate the cognitive prognosis for AD population.

  17. Towards a Pharmacophore for Amyloid

    Energy Technology Data Exchange (ETDEWEB)

    Landau, Meytal; Sawaya, Michael R.; Faull, Kym F.; Laganowsky, Arthur; Jiang, Lin; Sievers, Stuart A.; Liu, Jie; Barrio, Jorge R.; Eisenberg, David (UCLA)

    2011-09-16

    Diagnosing and treating Alzheimer's and other diseases associated with amyloid fibers remains a great challenge despite intensive research. To aid in this effort, we present atomic structures of fiber-forming segments of proteins involved in Alzheimer's disease in complex with small molecule binders, determined by X-ray microcrystallography. The fiber-like complexes consist of pairs of {beta}-sheets, with small molecules binding between the sheets, roughly parallel to the fiber axis. The structures suggest that apolar molecules drift along the fiber, consistent with the observation of nonspecific binding to a variety of amyloid proteins. In contrast, negatively charged orange-G binds specifically to lysine side chains of adjacent sheets. These structures provide molecular frameworks for the design of diagnostics and drugs for protein aggregation diseases. The devastating and incurable dementia known as Alzheimer's disease affects the thinking, memory, and behavior of dozens of millions of people worldwide. Although amyloid fibers and oligomers of two proteins, tau and amyloid-{beta}, have been identified in association with this disease, the development of diagnostics and therapeutics has proceeded to date in a near vacuum of information about their structures. Here we report the first atomic structures of small molecules bound to amyloid. These are of the dye orange-G, the natural compound curcumin, and the Alzheimer's diagnostic compound DDNP bound to amyloid-like segments of tau and amyloid-{beta}. The structures reveal the molecular framework of small-molecule binding, within cylindrical cavities running along the {beta}-spines of the fibers. Negatively charged orange-G wedges into a specific binding site between two sheets of the fiber, combining apolar binding with electrostatic interactions, whereas uncharged compounds slide along the cavity. We observed that different amyloid polymorphs bind different small molecules, revealing that a

  18. Rescue of Early bace-1 and Global DNA Demethylation by S-Adenosylmethionine Reduces Amyloid Pathology and Improves Cognition in an Alzheimer’s Model

    Science.gov (United States)

    Do Carmo, Sonia; Hanzel, Cecilia E.; Jacobs, Marie L.; Machnes, Ziv; Iulita, M. Florencia; Yang, Jingyun; Yu, Lei; Ducatenzeiler, Adriana; Danik, Marc; Breuillaud, Lionel S.; Bennett, David A.; Szyf, Moshe; Cuello, A. Claudio

    2016-01-01

    General DNA hypomethylation is associated with Alzheimer’s disease (AD), but it is unclear when DNA hypomethylation starts or plays a role in AD pathology or whether DNA re-methylation would rescue early amyloid-related cognitive impairments. In an APP transgenic mouse model of AD-like amyloid pathology we found that early intraneuronal amyloid beta build-up is sufficient to unleash a global and beta-site amyloid precursor protein cleaving enzyme 1 (bace-1) DNA demethylation in AD-vulnerable brain regions. S-adenosylmethionine administration at these early stages abolished this hypomethylation, diminished the amyloid pathology and restored cognitive capabilities. To assess a possible human significance of findings, we examined the methylation at 12 CpGs sites in the bace-1 promoter, using genome-wide DNA methylation data from 740 postmortem human brains. Thus, we found significant associations of bace-1 promoter methylation with β-amyloid load among persons with AD dementia, and PHFtau tangle density. Our results support a plausible causal role for the earliest amyloid beta accumulation to provoke DNA hypomethylation, influencing AD pathological outcomes. PMID:27681803

  19. Prolyl oligopeptidase colocalizes with α-synuclein, β-amyloid, tau protein and astroglia in the post-mortem brain samples with Parkinson's and Alzheimer's diseases.

    Science.gov (United States)

    Hannula, M J; Myöhänen, T T; Tenorio-Laranga, J; Männistö, P T; Garcia-Horsman, J A

    2013-07-09

    Prolyl oligopeptidase (EC 3.4.21.26, PREP) is a serine protease that hydrolyzes proline-containing peptides shorter than 30-mer but it has also nonhydrolytic functions. PREP has been shown to accelerate aggregation of wild-type α-synuclein (α-syn) under cell-free conditions, and PREP inhibitors can block this aggregation both in vitro and in vivo. α-syn is the main component of Lewy bodies in Parkinson's disease (PD) and Lewy body dementia. To clarify the possible interaction of PREP with other markers of neurodegenerative diseases, we studied colocalizations of PREP and (1) α-syn, (2) β-amyloid, (3) tau protein and (4) astroglial and microglial cells in human post-mortem brain samples from PD, Alzheimer's disease (AD) patients and in healthy control brain samples. In the substantia nigra of PD brains, an intense colocalization with PREP and α-syn was evident. PREP colocalized also with β-amyloid plaques in AD brains and with tau protein in AD and in healthy brains. PREP was also found in astroglial cells in PD, AD and control brains, but not in the microglia. Our findings are the first ones to demonstrate colocalization of PREP and pathological proteins in the human brain and support the view that, at least in spatial terms, PREP could be associated with pathogenesis of neurodegenerative diseases.

  20. Hacking the Code of Amyloid Formation

    Science.gov (United States)

    Pastor, M Teresa; Esteras-Chopo, Alexandra

    2007-01-01

    Many research efforts in the last years have been directed towards understanding the factors determining protein misfolding and amyloid formation. Protein stability and amino acid composition have been identified as the two major factors in vitro. The research of our group has been focused on understanding the relationship between amino acid sequence and amyloid formation. Our approach has been the design of simple model systems that reproduce the biophysical properties of natural amyloids. An amyloid sequence pattern was extracted that can be used to detect amyloidogenic hexapeptide stretches in proteins. We have added evidence supporting that these amyloidogenic stretches can trigger amyloid formation by nonamyloidogenic proteins. Some experimental results in other amyloid proteins will be analyzed under the conclusions obtained in these studies. Our conclusions together with evidences from other groups suggest that amyloid formation is the result of the interplay between a decrease of protein stability, and the presence of highly amyloidogenic regions in proteins. As many of these results have been obtained in vitro, the challenge for the next years will be to demonstrate their validity in in vivo systems. PMID:19164912

  1. Charge neutralization of the central lysine cluster in prion protein (PrP) promotes PrP(Sc)-like folding of recombinant PrP amyloids.

    Science.gov (United States)

    Groveman, Bradley R; Kraus, Allison; Raymond, Lynne D; Dolan, Michael A; Anson, Kelsie J; Dorward, David W; Caughey, Byron

    2015-01-09

    The structure of the infectious form of prion protein, PrP(Sc), remains unclear. Most pure recombinant prion protein (PrP) amyloids generated in vitro are not infectious and lack the extent of the protease-resistant core and solvent exclusion of infectious PrP(Sc), especially within residues ∼90-160. Polyanionic cofactors can enhance infectivity and PrP(Sc)-like characteristics of such fibrils, but the mechanism of this enhancement is unknown. In considering structural models of PrP(Sc) multimers, we identified an obstacle to tight packing that might be overcome with polyanionic cofactors, namely, electrostatic repulsion between four closely spaced cationic lysines within a central lysine cluster of residues 101-110. For example, in our parallel in-register intermolecular β-sheet model of PrP(Sc), not only would these lysines be clustered within the 101-110 region of the primary sequence, but they would have intermolecular spacings of only ∼4.8 Å between stacked β-strands. We have now performed molecular dynamics simulations predicting that neutralization of the charges on these lysine residues would allow more stable parallel in-register packing in this region. We also show empirically that substitution of these clustered lysine residues with alanines or asparagines results in recombinant PrP amyloid fibrils with extended proteinase-K resistant β-sheet cores and infrared spectra that are more reminiscent of bona fide PrP(Sc). These findings indicate that charge neutralization at the central lysine cluster is critical for the folding and tight packing of N-proximal residues within PrP amyloid fibrils. This charge neutralization may be a key aspect of the mechanism by which anionic cofactors promote PrP(Sc) formation.

  2. The prognostic value ofserum C-reactive protein-bound serum amyloid A inearly-stage lung cancer

    Institute of Scientific and Technical Information of China (English)

    XueYanZhang; GeZhang; YingJiang; DanLiu; ManZhiLi; QianZhong; ShanQiZeng; WanLiLiu; MuShengZeng

    2015-01-01

    Background:Elevated levels of serum C‑reactive protein (CRP) have been reported to have prognostic signiifcance in lung cancer patients. This study aimed to further identify CRP‑bound components as prognostic markers for lung cancer and validate their prognostic value. Methods:CRP‑bound components obtained from the serum samples from lung cancer patients or healthy controls were analyzed by differential proteomics analysis. CRP‑bound serum amyloid A (CRP‑SAA) was evaluated by co‑immunoprecipitation (IP). Serum samples from two independent cohorts with lung cancer (retrospective cohort, 242 patients; prospective cohort, 222 patients) and healthy controls (159 subjects) were used to evaluate the prognostic value of CRP‑SAA by enzyme‑linked immunosorbent assay. Results:CRP‑SAA was identiifed speciifcally in serum samples from lung cancer patients by proteomic analysis. CRP binding to SAA was conifrmed by co‑IP in serum samples from lung cancer patients and cell culture media. The level of CRP‑SAA was signiifcantly higher in patients than in healthy controls (0.37±0.58 vs. 0.03±0.04,P<0.001). Elevated CRP‑SAA levels were signiifcantly associated with severe clinical features of lung cancer. The elevation of CRP‑SAA was associated with lower survival rates for both the retrospective (hazard ration [HR]=2.181, 95% conifdence interval [CI]=1.641–2.897,P<0.001) and the prospective cohorts (HR=2.744, 95% CI=1.810–4.161,P<0.001). Multivariate Cox analysis showed that CRP‑SAA was an independent prognostic marker for lung cancer. Remarkably, in stages I–II patients, only CRP‑SAA, not total SAA or CRP, showed signiifcant association with overall survival in two cohorts. Moreover, univariate and multivariate Cox analyses also showed that only CRP‑SAA could be used as an inde‑pendent prognostic marker for early‑stage lung cancer patients. Conclusion:CRP‑SAA could be a better prognostic marker for lung cancer than total SAA or CRP

  3. Natural polyphenols binding to amyloid: a broad class of compounds to treat different human amyloid diseases.

    Science.gov (United States)

    Ngoungoure, Viviane L Ndam; Schluesener, Jan; Moundipa, Paul F; Schluesener, Hermann

    2015-01-01

    Polyphenols are a large group of phytonutrients found in herbal beverages and foods. They have manifold biological activities, including antioxidative, antimicrobial, and anti-inflammatory properties. Interestingly, some polyphenols bind to amyloid and substantially ameliorate amyloid diseases. Misfolding, aggregation, and accumulation of amyloid fibrils in tissues or organs leads to a group of disorders, called amyloidoses. Prominent diseases are Alzheimer's, Parkinson's, and Huntington's disease, but there are other, less well-known diseases wherein accumulation of misfolded protein is a prominent feature. Amyloidoses are a major burden to public health. In particular, Alzheimer's disease shows a strong increase in patient numbers. Accelerated development of effective therapies for amyloidoses is a necessity. A viable strategy can be the prevention or reduction of protein misfolding, thus reducing amyloid build-up by restoring the cellular aggretome. Amyloid-binding polyphenols affect amyloid formation on various levels, e.g. by inhibiting fibril formation or steering oligomer formation into unstructured, nontoxic pathways. Consequently, preclinical studies demonstrate reduction of amyloid-formation by polyphenols. Amyloid-binding polyphenols might be suitable lead structures for development of imaging agents for early detection of disease and monitoring amyloid deposition. Intake of dietary polyphenols might be relevant to the prevention of amyloidoses. Nutraceutical strategies might be a way to reduce amyloid diseases.

  4. Concentrations of C-reactive protein, serum amyloid A, and haptoglobin in uterine arterial and peripheral blood in bitches with pyometra.

    Science.gov (United States)

    Dąbrowski, Roman; Kostro, Krzysztof; Szczubiał, Marek

    2013-09-15

    Pyometra is a life-threatening reproductive disorder that affects the uterus of female dogs. This study was designed to identify the possible indicators of uterine inflammation by comparing C-reactive protein (CRP), serum amyloid A (SAA), and haptoglobin (Hp) concentrations in uterine arterial and peripheral venous blood in bitches with open- and closed-cervix pyometra. CRP, SAA, and Hp concentrations were higher in bitches with closed-cervix pyometra irrespective of the site of blood collection. Higher acute-phase protein concentrations were observed in peripheral compared with uterine arterial blood in bitches with closed-cervix pyometra, whereas the levels were comparable in dogs with open-cervix pyometra. Our results indicate that mean acute-phase protein concentrations differ according to pyometra type/severity and blood source and suggest the possible use of peripheral blood levels of CRP, SAA, and Hp to monitor inflammation during the course of pyometra.

  5. Minocycline corrects early, pre-plaque neuroinflammation and inhibits BACE-1 in a transgenic model of Alzheimer's disease-like amyloid pathology

    Directory of Open Access Journals (Sweden)

    Ferretti Maria

    2012-04-01

    Full Text Available Abstract Background A growing body of evidence indicates that inflammation is one of the earliest neuropathological events in Alzheimer's disease. Accordingly, we have recently shown the occurrence of an early, pro-inflammatory reaction in the hippocampus of young, three-month-old transgenic McGill-Thy1-APP mice in the absence of amyloid plaques but associated with intracellular accumulation of amyloid beta petide oligomers. The role of such a pro-inflammatory process in the progression of the pathology remained to be elucidated. Methods and results To clarify this we administered minocycline, a tetracyclic derivative with anti-inflammatory and neuroprotective properties, to young, pre-plaque McGill-Thy1-APP mice for one month. The treatment ended at the age of three months, when the mice were still devoid of plaques. Minocycline treatment corrected the up-regulation of inducible nitric oxide synthase and cyclooxygenase-2 observed in young transgenic placebo mice. Furthermore, the down-regulation of inflammatory markers correlated with a reduction in amyloid precursor protein levels and amyloid precursor protein-related products. Beta-site amyloid precursor protein cleaving enzyme 1 activity and levels were found to be up-regulated in transgenic placebo mice, while minocycline treatment restored these levels to normality. The anti-inflammatory and beta-secretase 1 effects could be partly explained by the inhibition of the nuclear factor kappa B pathway. Conclusions Our study suggests that the pharmacological modulation of neuroinflammation might represent a promising approach for preventing or delaying the development of Alzheimer's disease neuropathology at its initial, pre-clinical stages. The results open new vistas to the interplay between inflammation and amyloid pathology.

  6. Serum amyloid A, protein Z, and C4b-binding protein β chain as new potential biomarkers for pulmonary tuberculosis

    Science.gov (United States)

    Jiang, Ting-Ting; Shi, Li-Ying; Wei, Li-Liang; Li, Xiang; Yang, Su; Wang, Chong; Liu, Chang-Ming; Chen, Zhong-Liang; Tu, Hui-Hui; Li, Zhong-Jie; Li, Ji-Cheng

    2017-01-01

    The aim of this study was to discover novel biomarkers for pulmonary tuberculosis (TB). Differentially expressed proteins in the serum of patients with TB were screened and identified by iTRAQ-two dimensional liquid chromatography tandem mass spectrometry analysis. A total of 79 abnormal proteins were discovered in patients with TB compared with healthy controls. Of these, significant differences were observed in 47 abnormally expressed proteins between patients with TB or pneumonia and chronic obstructive pulmonary disease (COPD). Patients with TB (n = 136) exhibited significantly higher levels of serum amyloid A (SAA), vitamin K-dependent protein Z (PROZ), and C4b-binding protein β chain (C4BPB) than those in healthy controls (n = 66) (P<0.0001 for each) albeit significantly lower levels compared with those in patients with pneumonia (n = 72) (P<0.0001 for each) or COPD (n = 72) (P<0.0001, P<0.0001, P = 0.0016, respectively). After 6 months of treatment, the levels of SAA and PROZ were significantly increased (P = 0.022, P<0.0001, respectively), whereas the level of C4BPB was significantly decreased (P = 0.0038) in treated TB cases (n = 72). Clinical analysis showed that there were significant differences in blood clotting and lipid indices in patients with TB compared with healthy controls, patients with pneumonia or COPD, and treated TB cases (P<0.05). Correlation analysis revealed significant correlations between PROZ and INR (rs = 0.414, P = 0.044), and between C4BPB and FIB (rs = 0.617, P = 0.0002) in patients with TB. Receiver operating characteristic curve analysis revealed that the area under the curve value of the diagnostic model combining SAA, PROZ, and C4BPB to discriminate the TB group from the healthy control, pneumonia, COPD, and cured TB groups was 0.972, 0.928, 0.957, and 0.969, respectively. Together, these results suggested that SAA, PROZ, and C4BPB may serve as new potential biomarkers for TB. Our study may thus provide experimental data for

  7. Neuroprotective approaches in experimental models of beta-amyloid neurotoxicity : Relevance to Alzheimer's disease

    NARCIS (Netherlands)

    Harkany, T.; Hortobágyi, Tibor; Sasvari, M.; Konya, C.; Penke, B; Luiten, P.G.M.; Nyakas, C.

    1999-01-01

    1. beta-Amyloid peptides (A beta s) accumulate abundantly in the Alzheimer's disease (AD) brain in areas subserving information acquisition arid processing, and memory formation. A beta fragments are producedin a process of abnormal proteolytic cleavage of their precursor, the amyloid precursor prot

  8. Familial amyloid polyneuropathy.

    Science.gov (United States)

    Planté-Bordeneuve, Violaine; Said, Gerard

    2011-12-01

    Familial amyloid polyneuropathies (FAPs) are a group of life-threatening multisystem disorders transmitted as an autosomal dominant trait. Nerve lesions are induced by deposits of amyloid fibrils, most commonly due to mutated transthyretin (TTR). Less often the precursor of amyloidosis is mutant apolipoprotein A-1 or gelsolin. The first identified cause of FAP-the TTR Val30Met mutation-is still the most common of more than 100 amyloidogenic point mutations identified worldwide. The penetrance and age at onset of FAP among people carrying the same mutation vary between countries. The symptomatology and clinical course of FAP can be highly variable. TTR FAP typically causes a nerve length-dependent polyneuropathy that starts in the feet with loss of temperature and pain sensations, along with life-threatening autonomic dysfunction leading to cachexia and death within 10 years on average. TTR is synthesised mainly in the liver, and liver transplantation seems to have a favourable effect on the course of neuropathy, but not on cardiac or eye lesions. Oral administration of tafamidis meglumine, which prevents misfolding and deposition of mutated TTR, is under evaluation in patients with TTR FAP. In future, patients with FAP might benefit from gene therapy; however, genetic counselling is recommended for the prevention of all types of FAP.

  9. Lasso Peptide Biosynthetic Protein LarB1 Binds Both Leader and Core Peptide Regions of the Precursor Protein LarA.

    Science.gov (United States)

    Cheung, Wai Ling; Chen, Maria Y; Maksimov, Mikhail O; Link, A James

    2016-10-26

    Lasso peptides are a member of the superclass of ribosomally synthesized and posttranslationally modified peptides (RiPPs). Like all RiPPs, lasso peptides are derived from a gene-encoded precursor protein. The biosynthesis of lasso peptides requires two enzymatic activities: proteolytic cleavage between the leader peptide and the core peptide in the precursor protein, accomplished by the B enzymes, and ATP-dependent isopeptide bond formation, accomplished by the C enzymes. In a subset of lasso peptide biosynthetic gene clusters from Gram-positive organisms, the B enzyme is split between two proteins. One such gene cluster is found in the organism Rhodococcus jostii, which produces the antimicrobial lasso peptide lariatin. The B enzyme in R. jostii is split between two open reading frames, larB1 and larB2, both of which are required for lariatin biosynthesis. While the cysteine catalytic triad is found within the LarB2 protein, LarB1 is a PqqD homologue expected to bind to the lariatin precursor LarA based on its structural homology to other RiPP leader peptide binding domains. We show that LarB1 binds to the leader peptide of the lariatin precursor protein LarA with a sub-micromolar affinity. We used photocrosslinking with the noncanonical amino acid p-azidophenylalanine and mass spectrometry to map the interaction of LarA and LarB1. This analysis shows that the LarA leader peptide interacts with a conserved motif within LarB1 and, unexpectedly, the core peptide of LarA also binds to LarB1 in several positions. A Rosetta model built from distance restraints from the photocrosslinking experiments shows that the scissile bond between the leader peptide and core peptide in LarA is in a solvent-exposed loop.

  10. Cerebrospinal Fluid Amyloid Beta and Tau Concentrations Are Not Modulated by 16 Weeks of Moderate- to High-Intensity Physical Exercise in Patients with Alzheimer Disease

    DEFF Research Database (Denmark)

    Jensen, Camilla Steen; Portelius, Erik; Siersma, Volkert

    2016-01-01

    Background: Physical exercise may have some effect on cognition in patients with Alzheimer disease (AD). However, the underlying biochemical effects are unclear. Animal studies have shown that amyloid beta (Aβ), one of the pathological hallmarks of AD, can be altered with high levels of physical...... of Life, Physical Health and Functional Ability in Alzheimer's Disease: The Effect of Physical Exercise (ADEX) study we analyzed cerebrospinal fluid samples for Aβ species, total tau (t-tau), phosphorylated tau (p-tau) and soluble amyloid precursor protein (sAPP) species. We also assessed the patients...

  11. Pre-amyloid oligomers of the proteotoxic RepA-WH1 prionoid assemble at the bacterial nucleoid

    Science.gov (United States)

    Moreno-del Álamo, María; de la Espina, Susana Moreno-Díaz; Fernández-Tresguerres, M. Elena; Giraldo, Rafael

    2015-01-01

    Upon binding to short specific dsDNA sequences in vitro, the N-terminal WH1 domain of the plasmid DNA replication initiator RepA assembles as amyloid fibres. These are bundles of single or double twisted tubular filaments in which distorted RepA-WH1 monomers are the building blocks. When expressed in Escherichia coli, RepA-WH1 triggers the first synthetic amyloid proteinopathy in bacteria, recapitulating some of the features of mammalian prion diseases: it is vertically transmissible, albeit non-infectious, showing up in at least two phenotypically distinct and interconvertible strains. Here we report B3h7, a monoclonal antibody specific for oligomers of RepA-WH1, but which does not recognize the mature amyloid fibres. Unlike a control polyclonal antibody generated against the soluble protein, B3h7 interferes in vitro with DNA-promoted or amyloid-seeded assembly of RepA-WH1 fibres, thus the targeted oligomers are on-pathway amyloidogenic intermediates. Immuno-electron microscopy with B3h7 on thin sections of E. coli cells expressing RepA-WH1 consistently labels the bacterial nucleoid, but not the large cytoplasmic aggregates of the protein. This observation points to the nucleoid as the place where oligomeric amyloid precursors of RepA-WH1 are generated, and suggests that, once nucleated by DNA, further growth must continue in the cytoplasm due to entropic exclusion. PMID:26423724

  12. Transmembrane Protein 147 (TMEM147) Is a Novel Component of the Nicalin-NOMO Protein Complex*

    OpenAIRE

    Dettmer, Ulf; Kuhn, Peer-Hendrik; Abou-Ajram, Claudia; Lichtenthaler, Stefan F.; Krüger, Marcus; Kremmer, Elisabeth; Haass, Christian; Haffner, Christof

    2010-01-01

    Nicastrin and its relative Nicalin (Nicastrin-like protein) are both members of larger protein complexes, namely γ-secretase and the Nicalin-NOMO (Nodal modulator) complex. The γ-secretase complex, which contains Presenilin, APH-1, and PEN-2 in addition to Nicastrin, catalyzes the proteolytic cleavage of the transmembrane domain of various proteins including the β-amyloid precursor protein and Notch. Nicalin and its binding partner NOMO form a complex that was shown to modulate Nodal signalin...

  13. Characterization of Amyloid Cores in Prion Domains

    Science.gov (United States)

    Sant’Anna, Ricardo; Fernández, Maria Rosario; Batlle, Cristina; Navarro, Susanna; de Groot, Natalia S.; Serpell, Louise; Ventura, Salvador

    2016-01-01

    Amyloids consist of repetitions of a specific polypeptide chain in a regular cross-β-sheet conformation. Amyloid propensity is largely determined by the protein sequence, the aggregation process being nucleated by specific and short segments. Prions are special amyloids that become self-perpetuating after aggregation. Prions are responsible for neuropathology in mammals, but they can also be functional, as in yeast prions. The conversion of these last proteins to the prion state is driven by prion forming domains (PFDs), which are generally large, intrinsically disordered, enriched in glutamines/asparagines and depleted in hydrophobic residues. The self-assembly of PFDs has been thought to rely mostly on their particular amino acid composition, rather than on their sequence. Instead, we have recently proposed that specific amyloid-prone sequences within PFDs might be key to their prion behaviour. Here, we demonstrate experimentally the existence of these amyloid stretches inside the PFDs of the canonical Sup35, Swi1, Mot3 and Ure2 prions. These sequences self-assemble efficiently into highly ordered amyloid fibrils, that are functionally competent, being able to promote the PFD amyloid conversion in vitro and in vivo. Computational analyses indicate that these kind of amyloid stretches may act as typical nucleating signals in a number of different prion domains. PMID:27686217

  14. Characterization of the ectodomain of the envelope protein of dengue virus type 4: expression, membrane association, secretion and particle formation in the absence of precursor membrane protein.

    Directory of Open Access Journals (Sweden)

    Szu-Chia Hsieh

    Full Text Available The envelope (E of dengue virus (DENV is the major target of neutralizing antibodies and vaccine development. After biosynthesis E protein forms a heterodimer with precursor membrane (prM protein. Recent reports of infection enhancement by anti-prM monoclonal antibodies (mAbs suggest anti-prM responses could be potentially harmful. Previously, we studied a series of C-terminal truncation constructs expressing DENV type 4 prM/E or E proteins and found the ectodomain of E protein alone could be recognized by all 12 mAbs tested, suggesting E protein ectodomain as a potential subunit immunogen without inducing anti-prM response. The characteristics of DENV E protein ectodomain in the absence of prM protein remains largely unknown.In this study, we investigated the expression, membrane association, glycosylation pattern, secretion and particle formation of E protein ectodomain of DENV4 in the presence or absence of prM protein. E protein ectodomain associated with membrane in or beyond trans-Golgi and contained primarily complex glycans, whereas full-length E protein associated with ER membrane and contained high mannose glycans. In the absence of prM protein, E protein ectodomain can secrete as well as form particles of approximately 49 nm in diameter, as revealed by sucrose gradient ultracentrifugation with or without detergent and electron microscopy. Mutational analysis revealed that the secretion of E protein ectodomain was affected by N-linked glycosylation and could be restored by treatment with ammonia chloride.Considering the enhancement of DENV infectivity by anti-prM antibodies, our findings provide new insights into the expression and secretion of E protein ectodomain in the absence of prM protein and contribute to future subunit vaccine design.

  15. Effect of chronic intermittent hypoxia on the expression of Nip3, cell apoptosis, β-amyloid protein deposit in mice brain cortex

    Institute of Scientific and Technical Information of China (English)

    ZENG Yi-ming; CAI Kai-jin; CHEN Xiao-yong; WU Minx-ia; LIN Xi

    2009-01-01

    Background Chronic intermittent hypoxia (CIH) is the most important pathophysiologic feature of sleep apnea syndrome (SAS). To explore the relationship between SAS and dementia, the effects of CIH on the expression of Nip3, neuron apoptosis andβ-amyloid protein deposit in the brain cortex of the frontal lobe of mice were evaluated in this study. Methods Thirty male ICR mice were divided into four groups: control group (A, n=-10, sham hypoxia/reoxygenation), 2 weeks CIH group (B, n=-5), 4 weeks CIH group (C, n=-5), and 8 weeks CIH group (D, n=10). The ICR mice were placed in a chamber and exposed to intermittent hypoxia (oxygen concentration changed periodically from (21.72±0.55)% to (6.84±0.47)% every two minutes, eight hours per day). Neuron apoptosis of the cortex of the frontal lobe was detected by means of terminal deoxy-nucleotidyl transferase-mediated in situ end labeling (TUNEL). Immunohistochemical staining was performed for measuring expression of Nip3 and β-amyloid protein. The ultrastructure of neurons was observed under a transmission electron microscope. Results TUNEL positive neurons in each square millimeter in the cortex of the frontal lobe were categorized by median or Ri into group A (1,5.5), group B (133, 13), group C (252, 21), and group D (318, 24). There were significant differences among the above four groups (P=0.000). The significance test was performed between the control group and each CIH group respectively: group A and B (P>0.05); group A and C (P 0.05); groups A and C (P<0.005); and groups A and D (P<0.005). There was no significant difference between groups B and C, groups B and D, and groups C and D. The expression of Nip3 was closely correlated with neuron apoptosis in the brain (P <0.05). The expression ofβ-amyloid protein in the brain of mice was negative in all CIH groups and the control group. Ultrastructure observation showed karyopyknosis of nucleus, swelling of chondriosomes, deposit of lipofuscins and degeneration of

  16. Amyloid fibrils compared to peptide nanotubes.

    Science.gov (United States)

    Zganec, Matjaž; Zerovnik, Eva

    2014-09-01

    Prefibrillar oligomeric states and amyloid fibrils of amyloid-forming proteins qualify as nanoparticles. We aim to predict what biophysical and biochemical properties they could share in common with better researched peptide nanotubes. We first describe what is known of amyloid fibrils and prefibrillar aggregates (oligomers and protofibrils): their structure, mechanisms of formation and putative mechanism of cytotoxicity. In distinction from other neuronal fibrillar constituents, amyloid fibrils are believed to cause pathology, however, some can also be functional. Second, we give a review of known biophysical properties of peptide nanotubes. Finally, we compare properties of these two macromolecular states side by side and discuss which measurements that have already been done with peptide nanotubes could be done with amyloid fibrils as well.

  17. Transport of the GlcNAc-1-phosphotransferase α/β-subunit precursor protein to the Golgi apparatus requires a combinatorial sorting motif.

    Science.gov (United States)

    Franke, Mine; Braulke, Thomas; Storch, Stephan

    2013-01-11

    The Golgi-resident N-acetylglucosamine-1-phosphotransferase (PT) complex is composed of two α-, β-, and γ-subunits and represents the key enzyme for the biosynthesis of mannose 6-phosphate recognition marker on soluble lysosomal proteins. Mutations in the PT complex cause the lysosomal storage diseases mucolipidosis II and III. A prerequisite for the enzymatic activity is the site-1 protease-mediated cleavage of the PT α/β-subunit precursor protein in the Golgi apparatus. Here, we have investigated structural requirements of the PT α/β-subunit precursor protein for its efficient export from the endoplasmic reticulum (ER). Both wild-type and a cleavage-resistant type III membrane PT α/β-subunit precursor protein are exported whereas coexpressed separate α- and β-subunits failed to reach the cis-Golgi compartment. Mutational analyses revealed combinatorial, non-exchangeable dileucine and dibasic motifs located in a defined sequence context in the cytosolic N- and C-terminal domains that are required for efficient ER exit and subsequent proteolytic activation of the α/β-subunit precursor protein in the Golgi. In the presence of a dominant negative Sar1 mutant the ER exit of the PT α/β-subunit precursor protein is inhibited indicating its transport in coat protein complex II-coated vesicles. Expression studies of missense mutations identified in mucolipidosis III patients that alter amino acids in the N- and C-terminal domains demonstrated that the substitution of a lysine residue in close proximity to the dileucine sorting motif impaired ER-Golgi transport and subsequent activation of the PT α/β-subunit precursor protein. The data suggest that the oligomeric type III membrane protein PT complex requires a combinatorial sorting motif that forms a tertiary epitope to be recognized by distinct sites within the coat protein complex II machinery.

  18. Designed amyloid fibers as materials for selective carbon dioxide capture.

    Science.gov (United States)

    Li, Dan; Furukawa, Hiroyasu; Deng, Hexiang; Liu, Cong; Yaghi, Omar M; Eisenberg, David S

    2014-01-07

    New materials capable of binding carbon dioxide are essential for addressing climate change. Here, we demonstrate that amyloids, self-assembling protein fibers, are effective for selective carbon dioxide capture. Solid-state NMR proves that amyloid fibers containing alkylamine groups reversibly bind carbon dioxide via carbamate formation. Thermodynamic and kinetic capture-and-release tests show the carbamate formation rate is fast enough to capture carbon dioxide by dynamic separation, undiminished by the presence of water, in both a natural amyloid and designed amyloids having increased carbon dioxide capacity. Heating to 100 °C regenerates the material. These results demonstrate the potential of amyloid fibers for environmental carbon dioxide capture.

  19. Early-onset and robust amyloid pathology in a new homozygous mouse model of Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Antje Willuweit

    Full Text Available BACKGROUND: Transgenic mice expressing mutated amyloid precursor protein (APP and presenilin (PS-1 or -2 have been successfully used to model cerebral beta-amyloidosis, one of the characteristic hallmarks of Alzheimer's disease (AD pathology. However, the use of many transgenic lines is limited by premature death, low breeding efficiencies and late onset and high inter-animal variability of the pathology, creating a need for improved animal models. Here we describe the detailed characterization of a new homozygous double-transgenic mouse line that addresses most of these issues. METHODOLOGY/PRINCIPAL FINDINGS: The transgenic mouse line (ARTE10 was generated by co-integration of two transgenes carrying the K670N/M671L mutated amyloid precursor protein (APP(swe and the M146V mutated presenilin 1 (PS1 both under control of a neuron-specific promoter. Mice, hemi- as well as homozygous for both transgenes, are viable and fertile with good breeding capabilities and a low rate of premature death. They develop robust AD-like cerebral beta-amyloid plaque pathology with glial inflammation, signs of neuritic dystrophy and cerebral amyloid angiopathy. Using our novel image analysis algorithm for semi-automatic quantification of plaque burden, we demonstrate an early onset and progressive plaque deposition starting at 3 months of age in homozygous mice with low inter-animal variability and 100%-penetrance of the phenotype. The plaques are readily detected in vivo by PiB, the standard human PET tracer for AD. In addition, ARTE10 mice display early loss of synaptic markers and age-related cognitive deficits. By applying a gamma-secretase inhibitor we show a dose dependent reduction of soluble amyloid beta levels in the brain. CONCLUSIONS: ARTE10 mice develop a cerebral beta-amyloidosis closely resembling the beta-amyloid-related aspects of human AD neuropathology. Unifying several advantages of previous transgenic models, this line particularly qualifies for

  20. Extraskeletal problems and amyloid.

    Science.gov (United States)

    Drüeke, T B

    1999-12-01

    The major clinical manifestations of dialysis-associated A beta 2M amyloidosis are chronic arthralgias, destructive arthropathy and the carpal tunnel syndrome. For dialysis patients who have been maintained on renal replacement therapy for more than 10-15 years, this complication may become a major physical handicap. It may even be life-threatening in some instances due to cervical cord compression. Amyloid deposits in joint areas precede clinical symptoms and signs by several years. Systemic deposits may also occur but their clinical manifestations are infrequent. The diagnosis of dialysis arthropathy associated with beta 2-microglobulin-associated (A beta 2M) amyloidosis mostly relies on indirect clinical and radiological evidence. Histologic proof is rarely obtained in vivo. The pathogenesis of the disease is complex. It includes reduced elimination of beta 2M and potentially also as impaired degradation of A beta 2M as well as enhanced production of A beta 2M amyloid fibrils. Non enzymatic modifications of beta 2M probably play a role, including beta 2M protein modification with advanced glycation end-products (AGE) and advanced oxidation protein products. Modified beta 2M, collagen and proteoglycans appear actively involved in the induction of a local inflammatory response and beta 2M amyloid formation. There is also evidence in favor of treatment-related factors such as the type of hemodialysis membrane and the purity of dialysis water. Hopefully, the translation of our improving knowledge of all the factors involved will lead to a better treatment and eventually to the prevention of this dramatic complication of dialysis.

  1. PARP-1 modulates amyloid beta peptide-induced neuronal damage.

    Directory of Open Access Journals (Sweden)

    Sara Martire

    Full Text Available Amyloid beta peptide (Aβ causes neurodegeneration by several mechanisms including oxidative stress, which is known to induce DNA damage with the consequent activation of poly (ADP-ribose polymerase (PARP-1. To elucidate the role of PARP-1 in the neurodegenerative process, SH-SY5Y neuroblastoma cells were treated with Aβ25-35 fragment in the presence or absence of MC2050, a new PARP-1 inhibitor. Aβ25-35 induces an enhancement of PARP activity which is prevented by cell pre-treatment with MC2050. These data were confirmed by measuring PARP-1 activity in CHO cells transfected with amylod precursor protein and in vivo in brains specimens of TgCRND8 transgenic mice overproducing the amyloid peptide. Following Aβ25-35 exposure a significant increase in intracellular ROS was observed. These data were supported by the finding that Aβ25-35 induces DNA damage which in turn activates PARP-1. Challenge with Aβ25-35 is also able to activate NF-kB via PARP-1, as demonstrated by NF-kB impairment upon MC2050 treatment. Moreover, Aβ25-35 via PARP-1 induces a significant increase in the p53 protein level and a parallel decrease in the anti-apoptotic Bcl-2 protein. These overall data support the hypothesis of PARP-1 involvment in cellular responses induced by Aβ and hence a possible rationale for the implication of PARP-1 in neurodegeneration is discussed.

  2. Atomic View of a Toxic Amyloid Small Oligomer

    Energy Technology Data Exchange (ETDEWEB)

    Laganowsky, Arthur; Liu, Cong; Sawaya, Michael R.; Whitelegge, Julian P.; Park, Jiyong; Zhao, Minglei; Pensalfini, Anna; Soriaga, Angela B.; Landau, Meytal; Teng, Poh K.; Cascio, Duilio; Glabe, Charles; Eisenberg, David (UCI); (UCLA)

    2012-04-30

    Amyloid diseases, including Alzheimer's, Parkinson's, and the prion conditions, are each associated with a particular protein in fibrillar form. These amyloid fibrils were long suspected to be the disease agents, but evidence suggests that smaller, often transient and polymorphic oligomers are the toxic entities. Here, we identify a segment of the amyloid-forming protein {alpha}{beta} crystallin, which forms an oligomeric complex exhibiting properties of other amyloid oligomers: {beta}-sheet-rich structure, cytotoxicity, and recognition by an oligomer-specific antibody. The x-ray-derived atomic structure of the oligomer reveals a cylindrical barrel, formed from six antiparallel protein strands, that we term a cylindrin. The cylindrin structure is compatible with a sequence segment from the {beta}-amyloid protein of Alzheimer's disease. Cylindrins offer models for the hitherto elusive structures of amyloid oligomers.

  3. Binding of complement proteins C1q and C4bp to serum amyloid P component (SAP) in solid contra liquid phase

    DEFF Research Database (Denmark)

    Sørensen, Inge Juul; Nielsen, EH; Andersen, Ove;

    1996-01-01

    Serum amyloid P component (SAP), a member of the conserved pentraxin family of plasma proteins, binds calcium dependently to its ligands. The authors investigated SAPs interaction with the complement proteins C4b binding protein (C4bp) and C1q by ELISA, immunoelectrophoresis and electron microscopy....... Binding of these proteins to SAP was demonstrated when SAP was immobilized using F(ab')2 anti-SAP, but not when SAP reacted with these proteins in liquid phase; thus the binding to human SAP was markedly phase state dependent. Presaturation of solid phase SAP with heparin, which binds SAP with high...... affinity, did not interfere with the subsequent binding of C4bp or C1q to SAP. In contrast, collagen I and IV showed partial competition with the binding of C1q to SAP. Using fresh serum, immobilized native SAP bound C4bp whereas binding of C1q/C1 could not be demonstrated. Altogether the results indicate...

  4. The Alzheimer's Amyloid-Degrading Peptidase, Neprilysin: Can We Control It?

    Directory of Open Access Journals (Sweden)

    N. N. Nalivaeva

    2012-01-01

    Full Text Available The amyloid cascade hypothesis of Alzheimer's disease (AD postulates that accumulation in the brain of amyloid β-peptide (Aβ is the primary trigger for neuronal loss specific to this pathology. In healthy brain, Aβ levels are regulated by a dynamic equilibrium between Aβ release from the amyloid precursor protein (APP and its removal by perivascular drainage or by amyloid-degrading enzymes (ADEs. During the last decade, the ADE family was fast growing, and currently it embraces more than 20 members. There are solid data supporting involvement of each of them in Aβ clearance but a zinc metallopeptidase neprilysin (NEP is considered as a major ADE. NEP plays an important role in brain function due to its role in terminating neuropeptide signalling and its decrease during ageing or after such pathologies as hypoxia or ischemia contribute significantly to the development of AD pathology. The recently discovered mechanism of epigenetic regulation of NEP by the APP intracellular domain (AICD opens new avenues for its therapeutic manipulation and raises hope for developing preventive strategies in AD. However, consideration needs to be given to the diverse physiological roles of NEP. This paper critically evaluates general biochemical and physiological functions of NEP and their therapeutic relevance.

  5. Amyloid Imaging in Aging and Dementia: Testing the Amyloid Hypothesis In Vivo

    Directory of Open Access Journals (Sweden)

    G. D. Rabinovici

    2009-01-01

    Full Text Available Amyloid imaging represents a major advance in neuroscience, enabling the detection and quantification of pathologic protein aggregations in the brain. In this review we survey current amyloid imaging techniques, focusing on positron emission tomography (PET with ^{11}carbon-labelled Pittsburgh Compound-B (11C-PIB, the most extensively studied and best validated tracer. PIB binds specifically to fibrillar beta-amyloid (Aβ deposits, and is a sensitive marker for Aβ pathology in cognitively normal older individuals and patients with mild cognitive impairment (MCI and Alzheimer’s disease (AD. PIB-PET provides us with a powerful tool to examine in vivo the relationship between amyloid deposition, clinical symptoms, and structural and functional brain changes in the continuum between normal aging and AD. Amyloid imaging studies support a model in which amyloid deposition is an early event on the path to dementia, beginning insidiously in cognitively normal individuals, and accompanied by subtle cognitive decline and functional and structural brain changes suggestive of incipient AD. As patients progress to dementia, clinical decline and neurodegeneration accelerate and proceed independently of amyloid accumulation. In the future, amyloid imaging is likely to supplement clinical evaluation in selecting patients for anti-amyloid therapies, while MRI and FDG-PET may be more appropriate markers of clinical progression.

  6. Atypical presentation of atypical amyloid.

    Science.gov (United States)

    Holanda, Danniele G; Acharya, Veena K; Dogan, Ahmet; Racusen, Lorraine C; Atta, Mohamed G

    2011-01-01

    Amyloidosis is a group of diseases categorized by precipitation of a group of protein aggregates (amyloid) in tissues, including the kidney, and proteinuria is usually the commonest, though not exclusive, hallmark of clinical presentation. AL and AA are the most commonly recognized forms of amyloidosis involving the kidney, but other forms have been described. We present a case of renal amyloidosis due to a novel amyloidogenic protein, leucocyte cell-derived chemotaxin 2, without proteinuria at presentation or on subsequent follow-up.

  7. Regulation of serum amyloid A gene expression in Syrian hamsters by cytokines.

    Science.gov (United States)

    Dowton, S B; Peters, C N; Jestus, J J

    1991-10-01

    Amyloid A (AA) protein is derived from serum amyloid A (SAA) and deposited as beta-pleated sheet fibrils in reactive amyloidosis, a disease that occurs spontaneously in golden Syrian hamsters. The precursor SAA is an acute-phase reactant in many species including hamsters, and in this report we have defined the in vivo kinetic and dosage responses for SAA mRNA accumulation in hamsters following administration of various cytokines. Elevations in levels of hepatic SAA mRNA were documented when the doses of interleukin-1, interleukin-6, and tumor necrosis factor were increased. The increase in dosages applied ranged from 2 1/2-fold for interleukin-6 to 10-fold for interleukin-1. SAA transcript levels were highest 8 h following administration of interleukin-6 or tumor necrosis factor, whereas maximal amounts of SAA-specific mRNA were found 24 h after administration of interleukin-1.

  8. A complex between contactin-1 and the protein tyrosine phosphatase PTPRZ controls the development of oligodendrocyte precursor cells

    Energy Technology Data Exchange (ETDEWEB)

    Lamprianou, Smaragda; Chatzopoulou, Elli; Thomas, Jean-Léon; Bouyain, Samuel; Harroch, Sheila (IP-Korea); (UPMC); (UMKC)

    2013-09-23

    The six members of the contactin (CNTN) family of neural cell adhesion molecules are involved in the formation and maintenance of the central nervous system (CNS) and have been linked to mental retardation and neuropsychiatric disorders such as autism. Five of the six CNTNs bind to the homologous receptor protein tyrosine phosphatases gamma (PTPRG) and zeta (PTPRZ), but the biological roles of these interactions remain unclear. We report here the cocrystal s