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Sample records for amyloid beta peptide

  1. Amyloid beta peptide immunotherapy in Alzheimer disease.

    Science.gov (United States)

    Delrieu, J; Ousset, P J; Voisin, T; Vellas, B

    2014-12-01

    Recent advances in the understanding of Alzheimer's disease pathogenesis have led to the development of numerous compounds that might modify the disease process. Amyloid β peptide represents an important molecular target for intervention in Alzheimer's disease. The main purpose of this work is to review immunotherapy studies in relation to the Alzheimer's disease. Several types of amyloid β peptide immunotherapy for Alzheimer's disease are under investigation, active immunization and passive administration with monoclonal antibodies directed against amyloid β peptide. Although immunotherapy approaches resulted in clearance of amyloid plaques in patients with Alzheimer's disease, this clearance did not show significant cognitive effect for the moment. Currently, several amyloid β peptide immunotherapy approaches are under investigation but also against tau pathology. Results from amyloid-based immunotherapy studies in clinical trials indicate that intervention appears to be more effective in early stages of amyloid accumulation in particular solanezumab with a potential impact at mild Alzheimer's disease, highlighting the importance of diagnosing Alzheimer's disease as early as possible and undertaking clinical trials at this stage. In both phase III solanezumab and bapineuzumab trials, PET imaging revealed that about a quarter of patients lacked fibrillar amyloid pathology at baseline, suggesting that they did not have Alzheimer's disease in the first place. So a new third phase 3 clinical trial for solanezumab, called Expedition 3, in patients with mild Alzheimer's disease and evidence of amyloid burden has been started. Thus, currently, amyloid intervention is realized at early stage of the Alzheimer's disease in clinical trials, at prodromal Alzheimer's disease, or at asymptomatic subjects or at risk to develop Alzheimer's disease and or at asymptomatic subjects with autosomal dominant mutation. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  2. Conformational changes of the amyloid beta-peptide (1-40) adsorbed on solid surfaces

    NARCIS (Netherlands)

    Giacomelli, CE; Norde, W

    2005-01-01

    The conformational change of the 39-43 residues of the amyloid beta-peptide (A beta) toward a beta-sheet enriched state promotes self-aggregation of the peptide molecules and constitutes the major peptide component of the amyloid plaques in Alzheimer patients. The crucial question behind the

  3. Conformational changes of the amyloid beta-peptide (1-40) adsorbed on solid surfaces

    NARCIS (Netherlands)

    Giacomelli, C.E.; Norde, W.

    2005-01-01

    The conformational change of the 39-43 residues of the amyloid beta -peptide (A beta) toward a beta -sheet enriched state promotes self-aggregation of the peptide molecules and constitutes the major peptide component of the amyloid plaques in Alzheimer patients. The crucial question behind the

  4. Interaction between amyloid beta peptide and an aggregation blocker peptide mimicking islet amyloid polypeptide.

    Directory of Open Access Journals (Sweden)

    Nasrollah Rezaei-Ghaleh

    Full Text Available Assembly of amyloid-beta peptide (Aβ into cytotoxic oligomeric and fibrillar aggregates is believed to be a major pathologic event in Alzheimer's disease (AD and interfering with Aβ aggregation is an important strategy in the development of novel therapeutic approaches. Prior studies have shown that the double N-methylated analogue of islet amyloid polypeptide (IAPP IAPP-GI, which is a conformationally constrained IAPP analogue mimicking a non-amyloidogenic IAPP conformation, is capable of blocking cytotoxic self-assembly of Aβ. Here we investigate the interaction of IAPP-GI with Aβ40 and Aβ42 using NMR spectroscopy. The most pronounced NMR chemical shift changes were observed for residues 13-20, while residues 7-9, 15-16 as well as the C-terminal half of Aβ--that is both regions of the Aβ sequence that are converted into β-strands in amyloid fibrils--were less accessible to solvent in the presence of IAPP-GI. At the same time, interaction of IAPP-GI with Aβ resulted in a concentration-dependent co-aggregation of Aβ and IAPP-GI that was enhanced for the more aggregation prone Aβ42 peptide. On the basis of the reduced toxicity of the Aβ peptide in the presence of IAPP-GI, our data are consistent with the suggestion that IAPP-GI redirects Aβ into nontoxic "off-pathway" aggregates.

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

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    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.

  6. Influence of hydrophobic Teflon particles on the structure of amyloid beta-peptide

    NARCIS (Netherlands)

    Giacomelli, C.E.; Norde, W.

    2003-01-01

    The amyloid beta-protein (Abeta) constitutes the major peptide component of the amyloid plaque deposits of Alzheimer's disease in humans. The Abeta changes from a nonpathogenic to a pathogenic conformation resulting in self-aggregation and deposition of the peptide. It has been established that

  7. Curcumin decreases amyloid-beta peptide levels by attenuating the maturation of amyloid-beta precursor protein.

    Science.gov (United States)

    Zhang, Can; Browne, Andrew; Child, Daniel; Tanzi, Rudolph E

    2010-09-10

    Alzheimer disease (AD) is a devastating neurodegenerative disease with no cure. The pathogenesis of AD is believed to be driven primarily by amyloid-beta (Abeta), the principal component of senile plaques. Abeta is an approximately 4-kDa peptide generated via cleavage of the amyloid-beta precursor protein (APP). Curcumin is a compound in the widely used culinary spice, turmeric, which possesses potent and broad biological activities, including anti-inflammatory and antioxidant activities, chemopreventative effects, and effects on protein trafficking. Recent in vivo studies indicate that curcumin is able to reduce Abeta-related pathology in transgenic AD mouse models via unknown molecular mechanisms. Here, we investigated the effects of curcumin on Abeta levels and APP processing in various cell lines and mouse primary cortical neurons. We show for the first time that curcumin potently lowers Abeta levels by attenuating the maturation of APP in the secretory pathway. These data provide a mechanism of action for the ability of curcumin to attenuate amyloid-beta pathology.

  8. Nasal administration of amyloid-beta peptide decreases cerebral amyloid burden in a mouse model of Alzheimer's disease

    DEFF Research Database (Denmark)

    Weiner, H L; Lemere, C A; Maron, R

    2000-01-01

    Progressive cerebral deposition of amyloid-beta (Abeta) peptide, an early and essential feature of Alzheimer's disease (AD), is accompanied by an inflammatory reaction marked by microgliosis, astrocytosis, and the release of proinflammatory cytokines. Mucosal administration of disease-implicated ......Progressive cerebral deposition of amyloid-beta (Abeta) peptide, an early and essential feature of Alzheimer's disease (AD), is accompanied by an inflammatory reaction marked by microgliosis, astrocytosis, and the release of proinflammatory cytokines. Mucosal administration of disease...... cerebral Abeta deposition, suggesting a novel mucosal immunological approach for the treatment and prevention of AD....

  9. Stereoselective determination of amino acids in beta-amyloid peptides and senile plaques.

    Science.gov (United States)

    Thorsén, G; Bergquist, J; Westlind-Danielsson, A; Josefsson, B

    2001-06-01

    A novel method for the determination of the enantiomeric composition of peptides is presented. In this paper, the focus has been on beta-amyloid peptides from deceased Alzheimer's disease patients. The peptides are hydrolyzed using mineral acid. The free amino acids are derivatized with the chiral reagent (+)- or (-)-1-(9-anthryl)-2-propyl chloroformate and subsequently separated using micellar electrokinetic chromatography (MEKC) and detected using laser-induced fluorescence (LIF) detection. The high separation efficiency of the MEKC-LIF system, yielding approximately 1 million theoretical plates/m for most amino acids, facilitates the simultaneous chiral determination of nine amino acids. The samples that have been analyzed were standard 1-40 beta-amyloid peptides, in vitro precipitated beta-amyloid fibrils, and human senile plaque samples.

  10. Pleomorphic copper coordination by Alzheimer's disease amyloid-beta peptide.

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    Drew, Simon C; Noble, Christopher J; Masters, Colin L; Hanson, Graeme R; Barnham, Kevin J

    2009-01-28

    Numerous conflicting models have been proposed regarding the nature of the Cu(2+) coordination environment of the amyloid beta (Abeta) peptide, the causative agent of Alzheimer's disease. This study used multifrequency CW-EPR spectroscopy to directly resolve the superhyperfine interactions between Cu(2+) and the ligand nuclei of Abeta, thereby avoiding ambiguities associated with introducing point mutations. Using a library of Abeta16 analogues with site-specific (15)N-labeling at Asp1, His6, His13, and His14, numerical simulations of the superhyperfine resonances delineated two independent 3N1O Cu(2+) coordination modes, {N(a)(D1), O, N(epsilon)(H6), N(epsilon)(H13)} (component Ia) and {N(a)(D1), O, N(epsilon)(H6), N(epsilon)(H14)} (component Ib), between pH 6-7. A third coordination mode (component II) was identified at pH 8.0, and simulation of the superhyperfine resonances indicated a 3N1O coordination sphere involving nitrogen ligation by His6, His13, and His14. No differences were observed upon (17)O-labeling of the phenolic oxygen of Tyr10, confirming it is not a key oxygen ligand in the physiological pH range. Hyperfine sublevel correlation (HYSCORE) spectroscopy, in conjunction with site-specific (15)N-labeling, provided additional support for the common role of His6 in components Ia and Ib, and for the assignment of a {O, N(epsilon)(H6), N(epsilon)(H13), N(epsilon)(H14)} coordination sphere to component II. HYSCORE studies of a peptide analogue with selective (13)C-labeling of Asp1 revealed (13)C cross-peaks characteristic of equatorial coordination by the carboxylate oxygen of Asp1 in component Ia/b coordination. The direct resolution of Cu(2+) ligand interactions, together with the key finding that component I is composed of two distinct coordination modes, provides valuable insight into a range of conflicting ligand assignments and highlights the complexity of Cu(2+)/Abeta interactions.

  11. PEGylated nanoparticles bind to and alter amyloid-beta peptide conformation

    DEFF Research Database (Denmark)

    Brambilla, Davide; Verpillot, Romain; Le Droumaguet, Benjamin

    2012-01-01

    We have demonstrated that the polyethylene glycol (PEG) corona of long-circulating polymeric nanoparticles (NPs) favors interaction with the amyloid-beta (Aß(1-42)) peptide both in solution and in serum. The influence of PEGylation of poly(alkyl cyanoacrylate) and poly(lactic acid) NPs on the int......We have demonstrated that the polyethylene glycol (PEG) corona of long-circulating polymeric nanoparticles (NPs) favors interaction with the amyloid-beta (Aß(1-42)) peptide both in solution and in serum. The influence of PEGylation of poly(alkyl cyanoacrylate) and poly(lactic acid) NPs...

  12. Oxidative stress and the amyloid beta peptide in Alzheimer’s disease

    Directory of Open Access Journals (Sweden)

    C. Cheignon

    2018-04-01

    Full Text Available Oxidative stress is known to play an important role in the pathogenesis of a number of diseases. In particular, it is linked to the etiology of Alzheimer’s disease (AD, an age-related neurodegenerative disease and the most common cause of dementia in the elderly. Histopathological hallmarks of AD are intracellular neurofibrillary tangles and extracellular formation of senile plaques composed of the amyloid-beta peptide (Aβ in aggregated form along with metal-ions such as copper, iron or zinc. Redox active metal ions, as for example copper, can catalyze the production of Reactive Oxygen Species (ROS when bound to the amyloid-β (Aβ. The ROS thus produced, in particular the hydroxyl radical which is the most reactive one, may contribute to oxidative damage on both the Aβ peptide itself and on surrounding molecule (proteins, lipids, …. This review highlights the existing link between oxidative stress and AD, and the consequences towards the Aβ peptide and surrounding molecules in terms of oxidative damage. In addition, the implication of metal ions in AD, their interaction with the Aβ peptide and redox properties leading to ROS production are discussed, along with both in vitro and in vivo oxidation of the Aβ peptide, at the molecular level. Keywords: Oxidative stress, Amyloid beta peptide, Metal-ions, Reactive oxygen species, Oxidative damages

  13. Characterization of amyloid beta peptides from brain extracts of transgenic mice overexpressing the London mutant of human amyloid precursor protein.

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    Pype, Stefan; Moechars, Dieder; Dillen, Lieve; Mercken, Marc

    2003-02-01

    Alzheimer's disease (AD) is marked by the presence of neurofibrillary tangles and amyloid plaques in the brain of patients. To study plaque formation, we report on further quantitative and qualitative analysis of human and mouse amyloid beta peptides (Abeta) from brain extracts of transgenic mice overexpressing the London mutant of human amyloid precursor protein (APP). Using enzyme-linked immunosorbant assays (ELISAs) specific for either human or rodent Abeta, we found that the peptides from both species aggregated to form plaques. The ratios of deposited Abeta1-42/1-40 were in the order of 2-3 for human and 8-9 for mouse peptides, indicating preferential deposition of Abeta42. We also determined the identity and relative levels of other Abeta variants present in protein extracts from soluble and insoluble brain fractions. This was done by combined immunoprecipitation and mass spectrometry (IP/MS). The most prominent peptides truncated either at the carboxyl- or the amino-terminus were Abeta1-38 and Abeta11-42, respectively, and the latter was strongly enriched in the extracts of deposited peptides. Taken together, our data indicate that plaques of APP-London transgenic mice consist of aggregates of multiple human and mouse Abeta variants, and the human variants that we identified were previously detected in brain extracts of AD patients.

  14. {beta} - amyloid imaging probes

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    Jeong, Jae Min [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2007-04-15

    Imaging distribution of {beta} - amyloid plaques in Alzheimer's disease is very important for early and accurate diagnosis. Early trial of the {beta} -amyloid plaques includes using radiolabeled peptides which can be only applied for peripheral {beta} - amyloid plaques due to limited penetration through the blood brain barrier (BBB). Congo red or Chrysamine G derivatives were labeled with Tc-99m for imaging {beta} - amyloid plaques of Alzheimer patient's brain without success due to problem with BBB penetration. Thioflavin T derivatives gave breakthrough for {beta} - amyloid imaging in vivo, and a benzothiazole derivative [C-11]6-OH-BTA-1 brought a great success. Many other benzothiazole, benzoxazole, benzofuran, imidazopyridine, and styrylbenzene derivatives have been labeled with F-18 and I-123 to improve the imaging quality. However, [C-11]6-OH-BTA-1 still remains as the best. However, short half-life of C-11 is a limitation of wide distribution of this agent. So, it is still required to develop an Tc-99m, F-18 or I-123 labeled agent for {beta} - amyloid imaging agent.

  15. The Aggregation Potential of the 1-15-and 1-16-Fragments of the Amyloid beta Peptide and Their Influence on the Aggregation of A beta 40

    NARCIS (Netherlands)

    Shabestari, M.; Plug, T.; Motazacker, M. M.; Meeuwenoord, N. J.; Filippov, D. V.; Meijers, J. C. M.; Huber, M.

    2013-01-01

    The aggregation of amyloid beta (A beta) peptide is important in Alzheimer's disease. Shorter A beta fragments may reduce A beta's cytotoxicity and are used in diagnostics. The aggregation of A beta 16 is controversial; Liu et al. (J. Neurosci. Res. 75:162-171, 2004) and Liao et al. (FEBS Lett.

  16. Aggregation and toxicity of amyloid-beta peptide in relation to peptide sequence variation

    OpenAIRE

    Vandersteen, A.

    2012-01-01

    Generally, aggregation of the amyloidpeptide is considered the cause of neuronal death in Alzheimer disease. The heterogenous Aß peptide occurs in various lengths in vivo: Aß40 and Aß42 are the predominant forms while both shorter and longer peptides exist. Aß40 and shorter isoforms are less aggregation-prone and hence considered less dangerous than Aß42 and longer isoforms, which are more aggregation-prone. Up to now research mainly focussed on the predominant Aß peptides and their indivi...

  17. Beta-amyloid peptides undergo regulated co-secretion with neuropeptide and catecholamine neurotransmitters.

    Science.gov (United States)

    Toneff, Thomas; Funkelstein, Lydiane; Mosier, Charles; Abagyan, Armen; Ziegler, Michael; Hook, Vivian

    2013-08-01

    Beta-amyloid (Aβ) peptides are secreted from neurons, resulting in extracellular accumulation of Aβ and neurodegeneration of Alzheimer's disease. Because neuronal secretion is fundamental for the release of neurotransmitters, this study assessed the hypothesis that Aβ undergoes co-release with neurotransmitters. Model neuronal-like chromaffin cells were investigated, and results illustrate regulated, co-secretion of Aβ(1-40) and Aβ(1-42) with peptide neurotransmitters (galanin, enkephalin, and NPY) and catecholamine neurotransmitters (dopamine, norepinephrine, and epinephrine). Regulated secretion from chromaffin cells was stimulated by KCl depolarization and nicotine. Forskolin, stimulating cAMP, also induced co-secretion of Aβ peptides with peptide and catecholamine neurotransmitters. These data suggested the co-localization of Aβ with neurotransmitters in dense core secretory vesicles (DCSV) that store and secrete such chemical messengers. Indeed, Aβ was demonstrated to be present in DCSV with neuropeptide and catecholamine transmitters. Furthermore, the DCSV organelle contains APP and its processing proteases, β- and γ-secretases, that are necessary for production of Aβ. Thus, Aβ can be generated in neurotransmitter-containing DCSV. Human IMR32 neuroblastoma cells also displayed regulated secretion of Aβ(1-40) and Aβ(1-42) with the galanin neurotransmitter. These findings illustrate that Aβ peptides are present in neurotransmitter-containing DCSV, and undergo co-secretion with neuropeptide and catecholamine neurotransmitters that regulate brain functions. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Controlling amyloid-beta peptide(1-42) oligomerization and toxicity by fluorinated nanoparticles.

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    Saraiva, Ana M; Cardoso, Isabel; Pereira, M Carmo; Coelho, Manuel A N; Saraiva, Maria João; Möhwald, Helmuth; Brezesinski, Gerald

    2010-09-03

    The amyloid-beta peptide (Abeta) is a major fibrillar component of neuritic plaques in Alzheimer's disease brains and is related to the pathogenesis of the disease. Soluble oligomers that precede fibril formation have been proposed as the main neurotoxic species that contributes to neurodegeneration and dementia. We hypothesize that oligomerization and cytotoxicity can be repressed by nanoparticles (NPs) that induce conformational changes in Abeta42. We show here that fluorinated and hydrogenated NPs with different abilities to change Abeta42 conformation influence oligomerization as assessed by atomic force microscopy, immunoblot and SDS-PAGE. Fluorinated NPs, which promote an increase in alpha-helical content, exert an antioligomeric effect, whereas hydrogenated analogues do not and lead to aggregation. Cytotoxicity assays confirmed our hypothesis by indicating that the conformational conversion of Abeta42 into an alpha-helical-enriched secondary structure also has antiapoptotic activity, thereby increasing the viability of cells treated with oligomeric species.

  19. Bloodstream Amyloid-beta (1-40) Peptide, Cognition, and Outcomes in Heart Failure.

    Science.gov (United States)

    Bayes-Genis, Antoni; Barallat, Jaume; de Antonio, Marta; Domingo, Mar; Zamora, Elisabet; Vila, Joan; Subirana, Isaac; Gastelurrutia, Paloma; Pastor, M Cruz; Januzzi, James L; Lupón, Josep

    2017-11-01

    In the brain, amyloid-beta generation participates in the pathophysiology of cognitive disorders; in the bloodstream, the role of amyloid-beta is uncertain but may be linked to sterile inflammation and senescence. We explored the relationship between blood levels of amyloid-beta 1-40 peptide (Aβ40), cognition, and mortality (all-cause, cardiovascular, and heart failure [HF]-related) in ambulatory patients with HF. Bloodstream Aβ40 was measured in 939 consecutive patients with HF. Cognition was evaluated with the Pfeiffer questionnaire (adjusted for educational level) at baseline and during follow-up. Multivariate Cox regression analyses and measurements of performance (discrimination, calibration, and reclassification) were used, with competing risk for specific causes of death. Over 5.1 ± 2.9 years, 471 patients died (all-cause): 250 from cardiovascular causes and 131 HF-related. The median Aβ40 concentration was 519.1 pg/mL [Q1-Q3: 361.8-749.9 pg/mL]. The Aβ40 concentration correlated with age, body mass index, renal dysfunction, and New York Heart Association functional class (all P < .001). There were no differences in Aβ40 in patients with and without cognitive impairment at baseline (P = .97) or during follow-up (P = .20). In multivariable analysis, including relevant clinical predictors and N-terminal pro-B-type natriuretic peptide, Aβ40 remained significantly associated with all-cause death (HR, 1.22; 95%CI, 1.10-1.35; P < .001) and cardiovascular death (HR, 1.18; 95%CI, 1.03-1.36; P = .02), but not with HF-related death (HR, 1.13; 95%CI, 0.93-1.37; P = .22). Circulating Aβ40 improved calibration and patient reclassification. Blood levels of Aβ40 are not associated with cognitive decline in HF. Circulating Aβ40 was predictive of mortality and may indicate systemic aging. Copyright © 2017 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

  20. Chronic exposure of NG108-15 cells to amyloid beta peptide (A beta(1-42)) abolishes calcium influx via N-type calcium channels

    Czech Academy of Sciences Publication Activity Database

    Kašparová, Jana; Lisá, Věra; Tuček, Stanislav; Doležal, Vladimír

    2001-01-01

    Roč. 26, 8-9 (2001), s. 1079-1084 ISSN 0364-3190 R&D Projects: GA MZd NF5183 Institutional research plan: CEZ:AV0Z5011922 Keywords : amyloid beta peptide * Alzheimer's disease * calcium Subject RIV: FH - Neurology Impact factor: 1.638, year: 2001

  1. The Alzheimer's disease-associated amyloid beta-protein is an antimicrobial peptide.

    Directory of Open Access Journals (Sweden)

    Stephanie J Soscia

    2010-03-01

    Full Text Available 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.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.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.

  2. 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

    component nor heparan sulfate did significantly alter the A beta-induced CA. The results indicate that not only fibrillar A beta but also oligomers of, in particular, beta 2M from patients with dialysis-associated amyloidosis are capable of inducing CA at supra-physiological concentrations....

  3. Lithium chloride increases the production of amyloid-beta peptide independently from its inhibition of glycogen synthase kinase 3.

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    Feyt, Christine; Kienlen-Campard, Pascal; Leroy, Karelle; N'Kuli, Francisca; Courtoy, Pierre J; Brion, Jean-Pierre; Octave, Jean-Noël

    2005-09-30

    Glycogen synthase kinase 3 (GSK3) is able to phosphorylate tau at many sites that are found to be phosphorylated in paired helical filaments in Alzheimer disease. Lithium chloride (LiCl) efficiently inhibits GSK3 and was recently reported to also decrease the production of amyloid-beta peptide (Abeta) from its precursor, the amyloid precursor protein. Therefore, lithium has been proposed as a combined therapeutic agent, inhibiting both the hyperphosphorylation of tau and the production of Abeta. Here, we demonstrate that the inhibition of GSK3 by LiCl induced the nuclear translocation of beta-catenin in Chinese hamster ovary cells and rat cultured neurons, in which a decrease in tau phosphorylation was observed. In both cellular models, a nontoxic concentration of LiCl increased the production of Abeta by increasing the beta-cleavage of amyloid precursor protein, generating more substrate for an unmodified gamma-secretase activity. SB415286, another GSK3 inhibitor, induced the nuclear translocation of beta-catenin and slightly decreased Abeta production. It is concluded that the LiCl-mediated increase in Abeta production is not related to GSK3 inhibition.

  4. Short-term effects of beta-amyloid25-35 peptide aggregates on transmitter release in neuromuscular synapses.

    Science.gov (United States)

    Garcia, Neus; Santafé, Manel M; Tomàs, Marta; Lanuza, Maria A; Tomàs, Josep

    2008-03-01

    The beta-amyloid (AB) peptide25-35 contains the functional domain of the AB precursor protein that is both required for neurotrophic effects in normal neural tissues and is involved in the neurotoxic effects in Alzheimer disease. We demonstrated the presence of the amyloid precursor protein/AB peptide in intramuscular axons, presynaptic motor nerve terminals, terminal and myelinating Schwann cells, and the postsynaptic and subsarcolemmal region in the Levator auris longus muscle of adult rats by immunocytochemistry. Using intracellular recording, we investigated possible short-term functional effects of the AB fragment (0.1-10 micromol/L) on acetylcholine release in adult and newborn motor end plates. We found no change in evoked, spontaneous transmitter release or resting membrane potential of the muscle cells. A previous block of the presynaptic muscarinic receptor subtypes and a previous block or stimulation of protein kinase C revealed no masked effect of the peptide on the regulation of transmitter release. The aggregated form of AB peptide25-35, however, interfered acutely with acetylcholine release (quantal content reduction) when synaptic activity was maintained by electric stimulation. The possible relevance of this inhibition of neurotransmission by AB peptide25-35 to the pathogenesis of Alzheimer remains to be determined.

  5. Evaluation of the amyloid beta-GFP fusion protein as a model of amyloid beta peptides-mediated aggregation: A study of DNAJB6 chaperone

    Directory of Open Access Journals (Sweden)

    Rasha Mohamed Hussein

    2015-07-01

    Full Text Available Alzheimer’s disease is a progressive neurodegenerative disease characterized by the accumulation and aggregation of extracellular amyloid β (Aβ peptides and intracellular aggregation of hyper-phosphorylated tau protein. Recent evidence indicates that accumulation and aggregation of intracellular amyloid β peptides may also play a role in disease pathogenesis. This would suggest that intracellular Heat Shock Proteins (HSP that maintain cellular protein homeostasis might be candidates for disease amelioration. We recently found that DNAJB6, a member of DNAJ family of heat shock proteins, effectively prevented the aggregation of short aggregation-prone peptides containing large poly glutamines (associated with CAG repeat diseases both in vitro and in cells. Moreover, recent in vitro data showed that DNAJB6 can delay the aggregation of Aβ42 peptides. In this study, we investigated the ability of DNAJB6 to prevent the aggregation of extracellular and intracellular Aβ peptides using transfection of HEK293 cells with Aβ-GFP fusion construct and performing western blotting and immunofluorescence techniques. We found that DNAJB6 indeed suppresses Aβ-GFP aggregation, but not seeded aggregation initiated by extracellular Aβ peptides. Unexpectedly and unlike what we found for peptide-mediated aggregation, DNAJB6 required interaction with HSP70 to prevent the aggregation of the Aβ-GFP fusion protein and its J-domain was crucial for its anti-aggregation effect. In addition, other DNAJ proteins as well as HSPA1a overexpression also suppressed Aβ-GFP aggregation efficiently. Our findings suggest that Aβ aggregation differs from poly Q peptide induced aggregation in terms of chaperone handling and sheds doubt on the usage of Aβ-GFP fusion construct for studying Aβ peptide aggregation in cells.

  6. Einfluß einer In-vitro- und In-vivo-Cholesterol-Modulation in Hirnmembranen auf die zellulären Effekte von Amyloid-beta-Peptid

    OpenAIRE

    Kirsch, Christopher

    2003-01-01

    Die exzessive Bildung und Ablagerung von aggregiertem Amyloid beta-Peptid im Gehirn von Alzheimer Patienten wird allgemein als zentrales Ereignis im Rahmen des Neurodegenerationsprozesses der Alzheimer Demenz betrachtet. Der Amyloid-Stoffwechsel ist dabei in sehr vielfältiger Weise mit dem zellulären Cholesterol-Stoffwechsel verknüpft. Hohe Cholesterolspiegel in spezifischen Membrandomänen wie Lipid-Rafts forcieren sehr wahrscheinlich die zelluläre Produktion als auch die Fibrillogenese von A...

  7. Iron and aluminum interaction with amyloid-beta peptides associated with Alzheimer’s disease

    Energy Technology Data Exchange (ETDEWEB)

    Drochioiu, Gabi; Ion, Laura [Alexandru Ioan Cuza University of Iasi, 11 Carol I, Iasi 700506 (Romania); Murariu, Manuela; Habasescu, Laura [Petru Poni Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, Iasi 700487 (Romania)

    2014-10-06

    An elevation in the concentration of heavy metal ions in Alzheimer’s disease (AD) brain has been demonstrated in many studies. Aβ precipitation and toxicity in AD brains seem to be caused by abnormal interactions with neocortical metal ions, especially iron, copper, zinc, and aluminum [1–3]. There is increasing evidence that iron and aluminum ions are involved in the mechanisms that underlie the neurodegenerative diseases [4,5]. However, evidence was brought to demonstrate that some Aβ fragments, at physiological pH, are not able to form binary complexes with Fe(III) ions of sufficient stability to compete with metal hydroxide precipitation [6]. On the contrary, multiple metal ions are known to interact with Aβ peptides [7]. Consequently, we investigated here the interaction of Fe(II/III) and Al(III) ions with some amyloidpeptides and fragments that results in peptide aggregation and fibrillation [8,9]. Infrared spectroscopy, atomic force microscopy, scanning electron microscopy, electrophoresis and mass spectrometry demonstrated conformational changes of peptides in the presence of such metals.

  8. Recombinant amyloid beta-peptide production by coexpression with an affibody ligand

    Directory of Open Access Journals (Sweden)

    Dobson Christopher M

    2008-10-01

    Full Text Available Abstract Background Oligomeric and fibrillar aggregates of the amyloid β-peptide (Aβ have been implicated in the pathogenesis of Alzheimer's disease (AD. The characterization of Aβ assemblies is essential for the elucidation of the mechanisms of Aβ neurotoxicity, but requires large quantities of pure peptide. Here we describe a novel approach to the recombinant production of Aβ. The method is based on the coexpression of the affibody protein ZAβ3, a selected affinity ligand derived from the Z domain three-helix bundle scaffold. ZAβ3 binds to the amyloidogenic central and C-terminal part of Aβ with nanomolar affinity and consequently inhibits aggregation. Results Coexpression of ZAβ3 affords the overexpression of both major Aβ isoforms, Aβ(1–40 and Aβ(1–42, yielding 4 or 3 mg, respectively, of pure 15N-labeled peptide per liter of culture. The method does not rely on a protein-fusion or -tag and thus does not require a cleavage reaction. The purified peptides were characterized by NMR, circular dichroism, SDS-PAGE and size exclusion chromatography, and their aggregation propensities were assessed by thioflavin T fluorescence and electron microscopy. The data coincide with those reported previously for monomeric, largely unstructured Aβ. ZAβ3 coexpression moreover permits the recombinant production of Aβ(1–42 carrying the Arctic (E22G mutation, which causes early onset familial AD. Aβ(1–42E22G is obtained in predominantly monomeric form and suitable, e.g., for NMR studies. Conclusion The coexpression of an engineered aggregation-inhibiting binding protein offers a novel route to the recombinant production of amyloidogenic Aβ peptides that can be advantageously employed to study the molecular basis of AD. The presented expression system is the first for which expression and purification of the aggregation-prone Arctic variant (E22G of Aβ(1–42 is reported.

  9. Recombinant amyloid beta-peptide production by coexpression with an affibody ligand

    Science.gov (United States)

    Macao, Bertil; Hoyer, Wolfgang; Sandberg, Anders; Brorsson, Ann-Christin; Dobson, Christopher M; Härd, Torleif

    2008-01-01

    Background Oligomeric and fibrillar aggregates of the amyloid β-peptide (Aβ) have been implicated in the pathogenesis of Alzheimer's disease (AD). The characterization of Aβ assemblies is essential for the elucidation of the mechanisms of Aβ neurotoxicity, but requires large quantities of pure peptide. Here we describe a novel approach to the recombinant production of Aβ. The method is based on the coexpression of the affibody protein ZAβ3, a selected affinity ligand derived from the Z domain three-helix bundle scaffold. ZAβ3 binds to the amyloidogenic central and C-terminal part of Aβ with nanomolar affinity and consequently inhibits aggregation. Results Coexpression of ZAβ3 affords the overexpression of both major Aβ isoforms, Aβ(1–40) and Aβ(1–42), yielding 4 or 3 mg, respectively, of pure 15N-labeled peptide per liter of culture. The method does not rely on a protein-fusion or -tag and thus does not require a cleavage reaction. The purified peptides were characterized by NMR, circular dichroism, SDS-PAGE and size exclusion chromatography, and their aggregation propensities were assessed by thioflavin T fluorescence and electron microscopy. The data coincide with those reported previously for monomeric, largely unstructured Aβ. ZAβ3 coexpression moreover permits the recombinant production of Aβ(1–42) carrying the Arctic (E22G) mutation, which causes early onset familial AD. Aβ(1–42)E22G is obtained in predominantly monomeric form and suitable, e.g., for NMR studies. Conclusion The coexpression of an engineered aggregation-inhibiting binding protein offers a novel route to the recombinant production of amyloidogenic Aβ peptides that can be advantageously employed to study the molecular basis of AD. The presented expression system is the first for which expression and purification of the aggregation-prone Arctic variant (E22G) of Aβ(1–42) is reported. PMID:18973685

  10. The prion protein as a receptor for amyloid-beta

    NARCIS (Netherlands)

    Kessels, Helmut W.; Nguyen, Louis N.; Nabavi, Sadegh; Malinow, Roberto

    2010-01-01

    Increased levels of brain amyloid-beta, a secreted peptide cleavage product of amyloid precursor protein (APP), is believed to be critical in the aetiology of Alzheimer's disease. Increased amyloid-beta can cause synaptic depression, reduce the number of spine protrusions (that is, sites of synaptic

  11. beta. -Amyloid gene dosage in Alzheimer's disease

    Energy Technology Data Exchange (ETDEWEB)

    Murdoch, G H; Manuelidis, L; Kim, J H; Manuelidis, E E

    1988-01-11

    The 4-5 kd amyloid ..beta..-peptide is a major constituent of the characteristic amyloid plaque of Alzheimer's disease. It has been reported that some cases of sporatic Alzheimer's disease are associated with at least a partial duplication of chromosome 21 containing the gene corresponding to the 695 residue precursor of this peptide. To contribute to an understanding of the frequency to such a duplication event in the overall Alzheimer's population, the authors have determined the gene dosage of the ..beta..-amyloid gene in this collection of cases. All cases had a clinical diagnosis of Alzheimer's confirmed neuropathologically. Each Alzheimer's case had an apparent normal diploid ..beta..-amyloid gene dosage, while control Down's cases had the expected triploid dosage. Thus partial duplication of chromosome 21 may be a rare finding in Alzheimer's disease. Similar conclusions were just reported in several studies of the Harvard Alzheimer collection.

  12. Chronic cladribine administration increases amyloid beta peptide generation and plaque burden in mice.

    Directory of Open Access Journals (Sweden)

    Crystal D Hayes

    Full Text Available The clinical uses of 2-chloro-2'-deoxyadenosine (2-CDA or cladribine which was initially prescribed to patients with hematological and lymphoid cancers is now extended to treat patients with multiple sclerosis (MS. Previous data has shown that 2-CDA has high affinity to the brain and readily passes through the blood brain barrier reaching CSF concentrations 25% of that found in plasma. However, whether long-term administration of 2-CDA can lead to any adverse effects in patients or animal models is not yet clearly known.Here we show that exposure of 2-CDA to CHO cells stably expressing wild-type APP751 increased generation and secretion of amyloid β peptide (Aβ in to the conditioned medium. Interestingly, increased Aβ levels were noticed even at non-toxic concentrations of 2-CDA. Remarkably, chronic treatment of APdE9 mice, a model of Alzheimer's disease with 2-CDA for 60 days increased amyloid plaque burden by more than 1-fold. Increased Aβ generation appears to result from increased turnover of APP as revealed by cycloheximide-chase experiments. Additionally, surface labeling of APP with biotin and immunoprecipitation of surface labeled proteins with anti-biotin antibody also indicated increased APP at the cell surface in 2-CDA treated cells compared to controls. Increased turnover of APP by 2-CDA in turn might be a consequence of decreased protein levels of PIN 1, which is known to regulate cis-trans isomerization and phosphorylation of APP. Most importantly, like many other oncology drugs, 2-CDA administration led to significant delay in acquiring a reward-based learning task in a T maze paradigm.Taken together, these data provide compelling evidence for the first time that chronic 2-CDA administration can increase amyloidogenic processing of APP leading to robustly increased plaque burden which may be responsible for the observed deficits in learning skills. Thus chronic treatment of mice with 2-CDA can have deleterious effects in vivo.

  13. The pathogenic implication of abnormal interaction between apolipoprotein E isoforms, amyloid-beta peptides, and sulfatides in Alzheimer's disease.

    Science.gov (United States)

    Han, Xianlin

    2010-06-01

    Alzheimer's disease (AD) is the most common cause of dementia in the aging population. Prior work has shown that the epsilon4 allele of apolipoprotein E (apoE4) is a major risk factor for "sporadic" AD, which accounts for >99% of AD cases without a defined underlying mechanism. Recently, we have demonstrated that sulfatides are substantially and specifically depleted at the very early stage of AD. To identify the mechanism(s) of sulfatide loss concurrent with AD onset, we have found that: (1) sulfatides are specifically associated with apoE-associated particles in cerebrospinal fluid (CSF); (2) apoE modulates cellular sulfatide levels; and (3) the modulation of sulfatide content is apoE isoform dependent. These findings not only lead to identification of the potential mechanisms underlying sulfatide depletion at the earliest stages of AD but also serve as mechanistic links to explain the genetic association of apoE4 with AD. Moreover, our recent studies further demonstrated that (1) apoE mediates sulfatide depletion in amyloid-beta precursor protein transgenic mice; (2) sulfatides enhance amyloid beta (Abeta) peptides binding to apoE-associated particles; (3) Abeta42 content notably correlates with sulfatide content in CSF; (4) sulfatides markedly enhance the uptake of Abeta peptides; and (5) abnormal sulfatide-facilitated Abeta uptake results in the accumulation of Abeta in lysosomes. Collectively, our studies clearly provide a link between apoE, Abeta, and sulfatides in AD and establish a foundation for the development of effective therapeutic interventions for AD.

  14. Towards Alzheimer's beta-amyloid vaccination.

    Science.gov (United States)

    Frenkel, D; Solomon, B

    2001-01-01

    Beta-amyloid pathology, the main hallmark of Alzheimer's disease (AD), has been linked to its conformational status and aggregation. We recently showed that site-directed monoclonal antibodies (mAbs) towards the N-terminal region of the human beta-amyloid peptide bind to preformed beta-amyloid fibrils (Abeta), leading to disaggregation and inhibition of their neurotoxic effect. Here we report the development of a novel immunization procedure to raise effective anti-aggregating amyloid beta-protein (AbetaP) antibodies, using as antigen filamentous phages displaying the only EFRH peptide found to be the epitope of these antibodies. Due to the high antigenicity of the phage no adjuvant is required to obtain high affinity anti-aggregating IgG antibodies in animals model, that exhibit identity to human AbetaP. Such antibodies are able to sequester peripheral AbetaP, thus avoiding passage through the blood brain barrier (BBB) and, as recently shown in a transgenic mouse model, to cross the BBB and dissolve already formed beta-amyloid plaques. To our knowledge, this is the first attempt to use as a vaccine a self-anti-aggregating epitope displayed on a phage, and this may pave the way to treat abnormal accumulation-peptide diseases, such as Alzheimer's disease or other amyloidogenic diseases. Copyright 2001 The International Association for Biologicals.

  15. The metabolic enhancer piracetam ameliorates the impairment of mitochondrial function and neurite outgrowth induced by beta-amyloid peptide.

    Science.gov (United States)

    Kurz, C; Ungerer, I; Lipka, U; Kirr, S; Schütt, T; Eckert, A; Leuner, K; Müller, W E

    2010-05-01

    beta-Amyloid peptide (Abeta) is implicated in the pathogenesis of Alzheimer's disease by initiating a cascade of events from mitochondrial dysfunction to neuronal death. The metabolic enhancer piracetam has been shown to improve mitochondrial dysfunction following brain aging and experimentally induced oxidative stress. We used cell lines (PC12 and HEK cells) and murine dissociated brain cells. The protective effects of piracetam in vitro and ex vivo on Abeta-induced impairment of mitochondrial function (as mitochondrial membrane potential and ATP production), on secretion of soluble Abeta and on neurite outgrowth in PC12 cells were investigated. Piracetam improves mitochondrial function of PC12 cells and acutely dissociated brain cells from young NMRI mice following exposure to extracellular Abeta(1-42). Similar protective effects against Abeta(1-42) were observed in dissociated brain cells from aged NMRI mice, or mice transgenic for mutant human amyloid precursor protein (APP) treated with piracetam for 14 days. Soluble Abeta load was markedly diminished in the brain of those animals after treatment with piracetam. Abeta production by HEK cells stably transfected with mutant human APP was elevated by oxidative stress and this was reduced by piracetam. Impairment of neuritogenesis is an important consequence of Abeta-induced mitochondrial dysfunction and Abeta-induced reduction of neurite growth in PC12 cells was substantially improved by piracetam. Our findings strongly support the concept of improving mitochondrial function as an approach to ameliorate the detrimental effects of Abeta on brain function.

  16. Monomeric Amyloid Beta Peptide in Hexafluoroisopropanol Detected by Small Angle Neutron Scattering.

    Directory of Open Access Journals (Sweden)

    Bo Zhang-Haagen

    Full Text Available Small proteins like amyloid beta (Aβ monomers are related to neurodegenerative disorders by aggregation to insoluble fibrils. Small angle neutron scattering (SANS is a nondestructive method to observe the aggregation process in solution. We show that SANS is able to resolve monomers of small molecular weight like Aβ for aggregation studies. We examine Aβ monomers after prolonged storing in d-hexafluoroisopropanol (dHFIP by using SANS and dynamic light scattering (DLS. We determined the radius of gyration from SANS as 1.0±0.1 nm for Aβ1-40 and 1.6±0.1 nm for Aβ1-42 in agreement with 3D NMR structures in similar solvents suggesting a solvent surface layer with 5% increased density. After initial dissolution in dHFIP Aβ aggregates sediment with a major component of pure monomers showing a hydrodynamic radius of 1.8±0.3 nm for Aβ1-40 and 3.2±0.4 nm for Aβ1-42 including a surface layer of dHFIP solvent molecules.

  17. Antagonizing beta-amyloid peptide neurotoxicity of the anti-aging fungus Ganoderma lucidum.

    Science.gov (United States)

    Lai, Cora Sau-Wan; Yu, Man-Shan; Yuen, Wai-Hung; So, Kwok-Fai; Zee, Sze-Yong; Chang, Raymond Chuen-Chung

    2008-01-23

    Ganoderma lucidum (Leyss. ex Fr.) Karst. (Lingzhi) is a medicinal fungus used clinically in many Asian countries to promote health and longevity. Synaptic degeneration is another key mode of neurodegeneration in Alzheimer's disease (AD). Recent studies have shown the loss of synaptic density proteins in each individual neuron during the progression of AD. It was recently reported that beta-amyloid (Abeta) could cause synaptic dysfunction and contribute to AD pathology. In this study, we reported that aqueous extract of G. lucidum significantly attenuated Abeta-induced synaptotoxicity by preserving the synaptic density protein, synaptophysin. In addition, G. lucidum aqueous extract antagonized Abeta-triggered DEVD cleavage activities in a dose-dependent manner. Further studies elucidated that phosphorylation of c-Jun N-terminal kinase, c-Jun, and p38 MAP kinase was attenuated by G. lucidum in Abeta-stressed neurons. Taken together, the results prove a hypothesis that anti-aging G. lucidum can prevent harmful effects of the exterminating toxin Abeta in AD.

  18. Microfluidic Isoelectric Focusing of Amyloid Beta Peptides Followed by Micropillar-Matrix-Assisted Laser Desorption Ionization-Mass Spectrometry.

    Science.gov (United States)

    Mikkonen, Saara; Jacksén, Johan; Roeraade, Johan; Thormann, Wolfgang; Emmer, Åsa

    2016-10-18

    A novel method for preconcentration and purification of the Alzheimer's disease related amyloid beta (Aβ) peptides by isoelectric focusing (IEF) in 75 nL microchannels combined with their analysis by micropillar-matrix-assisted laser desorption ionization-time-of-flight-mass spectrometry (MALDI-TOF-MS) is presented. A semiopen chip-based setup, consisting of open microchannels covered by a lid of a liquid fluorocarbon, was used. IEF was performed in a mixture of four small and chemically well-defined amphoteric carriers, glutamic acid, aspartyl-histidine (Asp-His), cycloserine (cSer), and arginine, which provided a stepwise pH gradient tailored for focusing of the C-terminal Aβ peptides with a pI of 5.3 in the boundary between cSer and Asp-His. Information about the focusing dynamics and location of the foci of Aβ peptides and other compounds was obtained using computer simulation and by performing MALDI-MS analysis directly from the open microchannel. With the established configuration, detection was performed by direct sampling of a nanoliter volume containing the focused Aβ peptides from the microchannel, followed by deposition of this volume onto a chip with micropillar MALDI targets. In addition to purification, IEF preconcentration provides at least a 10-fold increase of the MALDI-MS-signal. After immunoprecipitation and concentration of the eluate in the microchannel, IEF-micropillar-MALDI-MS is demonstrated to be a suitable platform for detection of Aβ peptides in human cerebrospinal fluid as well as in blood plasma.

  19. Neurine, an acetylcholine autolysis product, elevates secreted amyloid-beta protein precursor and amyloid-beta peptide levels, and lowers neuronal cell viability in culture: a role in Alzheimer's disease?

    Science.gov (United States)

    Tweedie, David; Brossi, Arnold; Chen, DeMoa; Ge, Yuan-Wen; Bailey, Jason; Yu, Qian-Sheng; Kamal, Mohammad A; Sambamurti, Kumar; Lahiri, Debomoy K; Greig, Nigel H

    2006-09-01

    Classical hallmarks of Alzheimer's disease (AD) are a synaptic loss, cholinergic neuron death, and abnormal protein deposition, particularly of toxic amyloid-beta peptide (Abeta) that is derived from amyloid-beta protein precursor (AbetaPP) by the action of beta- and gamma-secretases. The trigger(s) initiating the biochemical cascades that underpin these hallmarks have yet to be fully elucidated. The typical forebrain cholinergic cell demise associated with AD brain results in a loss of presynaptic cholinergic markers and acetylcholine (ACh). Neurine (vinyl-trimethyl-ammonium hydroxide) is a breakdown product of ACh, consequent to autolysis and is an organic poison found in cadavre brain. The time- and concentration-dependent actions of neurine were assessed in human neuroblastoma (NB, SK-N-SH) cells in culture by quantifying cell viability by lactate dehydrogenase (LDH) and MTS assay, and AbetaPP and Abeta levels by Western blot and ELISA. NB cells displayed evidence of toxicity to neurine at > or = 3 mg/ml, as demonstrated by elevated LDH levels in the culture media and a reduced cell viability shown by the MTS assay. Using subtoxic concentrations of neurine, elevations in AbetaPP and Abeta1-40 peptide levels were detected in conditioned media samples.

  20. Comparison of the amyloid pore forming properties of rat and human Alzheimer’s beta-amyloid peptide 1-42: Calcium imaging data

    Directory of Open Access Journals (Sweden)

    Coralie Di Scala

    2016-03-01

    Full Text Available The data here consists of calcium imaging of human neuroblastoma SH-SY5Y cells treated with the calcium-sensitive dye Fluo-4AM and then incubated with nanomolar concentrations of either human or rat Alzheimer’s β-amyloid peptide Aβ1-42. These data are both of a qualitative (fluorescence micrographs and semi-quantitative nature (estimation of intracellular calcium concentrations of cells probed by Aβ1-42 peptides vs. control untreated cells. Since rat Aβ1-42 differs from its human counterpart at only three amino acid positions, this comparative study is a good assessment of the specificity of the amyloid pore forming assay. The interpretation of this dataset is presented in the accompanying study “Broad neutralization of calcium-permeable amyloid pore channels with a chimeric Alzheimer/Parkinson peptide targeting brain gangliosides” [1].

  1. A systematic review of amyloid-beta peptides as putative mediators of the association between affective disorders and Alzheimer's disease

    DEFF Research Database (Denmark)

    Abbasowa, Leda; Heegaard, N. H. H.

    2014-01-01

    Background: Affective disorders are associated with an increased occurrence of cognitive deficits and have been linked to cognitive impairment and Alzheimer's disease. The putative molecular mechanisms involved in these associations are however not clear. The aim of this systematic review...... were limited by very low sample numbers. Finally, different assays for amyloid-beta were utilized in the different studies, thus hampering comparisons. Conclusion: To unravel possible risk relations and causalities between affective disorder and Alzheimer's disease and to determine how amyloid...

  2. CD147 is a regulatory subunit of the gamma-secretase complex inAlzheimer's disease amyloid beta-peptide production

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shuxia; Zhou, Hua; Walian, Peter J.; Jap, Bing K.

    2005-04-06

    {gamma}-secretase is a membrane protein complex that cleaves the {beta}-amyloid precursor protein (APP) within the transmembrane region, following prior processing by {beta}-secretase, producing amyloid {beta}-peptides (A{beta}{sub 40} and A{beta}{sub 42}). Errant production of A{beta}-peptides that substantially increases A{beta}{sub 42} production has been associated with the formation of amyloid plaques in Alzheimer's disease patients. Biophysical and genetic studies indicate that presenilin-1 (Psn-1), which contains the proteolytic active site, and three other membrane proteins, nicastrin (Nct), APH-1, and PEN-2 are required to form the core of the active {gamma}-secretase complex. Here, we report the purification of the native {gamma}-secretase complexes from HeLa cell membranes and the identification of an additional {gamma}-secretase complex subunit, CD147, a transmembrane glycoprotein with two immunoglobulin-like domains. The presence of this subunit as an integral part of the complex itself was confirmed through co-immunoprecipitation studies of the purified protein from HeLa cells and solubilized complexes from other cell lines such as neural cell HCN-1A and HEK293. Depletion of CD147 by RNA interference was found to increase the production of A{beta} peptides without changing the expression level of the other {gamma}-secretase components or APP substrates while CD147 overexpression had no statistically significant effect on amyloid {beta}-peptide production, other {gamma}-secretase components or APP substrates, indicating that the presence of the CD147 subunit within the {gamma}-secretase complex directly down-modulates the production of A{beta}-peptides. {gamma}-secretase was first recognized through its role in the production of the A{beta} peptides that are pathogenic in Alzheimer's disease (AD) (1). {gamma}-secretase is a membrane protein complex with unusual aspartyl protease activity that cleaves a variety of type I membrane proteins

  3. Effects of Capsule Yi -Zhi on learning and memory disorder and beta-amyloid peptide induced neurotoxicity in rats

    Institute of Scientific and Technical Information of China (English)

    XUJiang-Ping; WUHang-Yu; LILin

    2004-01-01

    AIM To investigate the effects of Capsule Yi-Zhi (CYZ) on learning and memory disorder and beta-amyloid protein induced neurotoxieity in rats. Methods Various doses of CYZ were administered to Sprague-Dawley (SD) rats for 8 days, twice a day. Then scopolamine hydrobromide (Sco) intraperitoneal injection was performed on each rat and the

  4. Amyloid beta-peptide(25-35) changes [Ca2+] in hippocampal neurons

    DEFF Research Database (Denmark)

    Mogensen, Helle Smidt; Beatty, D M; Morris, S J

    1998-01-01

    of A beta(25-35) on [Ca2+]i and intracellular H+ concentration ([H+]i) in single hippocampal neurons by real time fluorescence imaging using the Ca(2+)- and H(+)-specific ratio dyes, indo-1 and SNARF-1. Incubation of these cultures with A beta(25-35) for 3-12 days in vitro increased [Ca2+]i and [H......+]i in large, NMDA-responsive neurons....

  5. Resveratrol and Amyloid-Beta: Mechanistic Insights

    Directory of Open Access Journals (Sweden)

    Yongming Jia

    2017-10-01

    Full Text Available The amyloid-beta (Aβ hypothesis that dyshomeostasis between Aβ production and clearance is a very early, key molecular factor in the etiology of Alzheimer’s disease (AD has been proposed and examined in the AD research field. Scientists have focused on seeking natural products or drugs to influence the dynamic equilibrium of Aβ, targeting production and clearance of Aβ. There is emerging evidence that resveratrol (Res, a naturally occurring polyphenol mainly found in grapes and red wine, acts on AD in numerous in vivo and in vitro models. Res decreases the amyloidogenic cleavage of the amyloid precursor protein (APP, enhances clearance of amyloid beta-peptides, and reduces Aβ aggregation. Moreover, Res also protects neuronal functions through its antioxidant properties. This review discusses the action of Res on Aβ production, clearance and aggregation and multiple potential mechanisms, providing evidence of the useful of Res for AD treatment.

  6. How cholesterol constrains glycolipid conformation for optimal recognition of Alzheimer's beta amyloid peptide (Abeta1-40).

    Science.gov (United States)

    Yahi, Nouara; Aulas, Anaïs; Fantini, Jacques

    2010-02-05

    Membrane lipids play a pivotal role in the pathogenesis of Alzheimer's disease, which is associated with conformational changes, oligomerization and/or aggregation of Alzheimer's beta-amyloid (Abeta) peptides. Yet conflicting data have been reported on the respective effect of cholesterol and glycosphingolipids (GSLs) on the supramolecular assembly of Abeta peptides. The aim of the present study was to unravel the molecular mechanisms by which cholesterol modulates the interaction between Abeta(1-40) and chemically defined GSLs (GalCer, LacCer, GM1, GM3). Using the Langmuir monolayer technique, we show that Abeta(1-40) selectively binds to GSLs containing a 2-OH group in the acyl chain of the ceramide backbone (HFA-GSLs). In contrast, Abeta(1-40) did not interact with GSLs containing a nonhydroxylated fatty acid (NFA-GSLs). Cholesterol inhibited the interaction of Abeta(1-40) with HFA-GSLs, through dilution of the GSL in the monolayer, but rendered the initially inactive NFA-GSLs competent for Abeta(1-40) binding. Both crystallographic data and molecular dynamics simulations suggested that the active conformation of HFA-GSL involves a H-bond network that restricts the orientation of the sugar group of GSLs in a parallel orientation with respect to the membrane. This particular conformation is stabilized by the 2-OH group of the GSL. Correspondingly, the interaction of Abeta(1-40) with HFA-GSLs is strongly inhibited by NaF, an efficient competitor of H-bond formation. For NFA-GSLs, this is the OH group of cholesterol that constrains the glycolipid to adopt the active L-shape conformation compatible with sugar-aromatic CH-pi stacking interactions involving residue Y10 of Abeta(1-40). We conclude that cholesterol can either inhibit or facilitate membrane-Abeta interactions through fine tuning of glycosphingolipid conformation. These data shed some light on the complex molecular interplay between cell surface GSLs, cholesterol and Abeta peptides, and on the influence

  7. How cholesterol constrains glycolipid conformation for optimal recognition of Alzheimer's beta amyloid peptide (Abeta1-40.

    Directory of Open Access Journals (Sweden)

    Nouara Yahi

    Full Text Available Membrane lipids play a pivotal role in the pathogenesis of Alzheimer's disease, which is associated with conformational changes, oligomerization and/or aggregation of Alzheimer's beta-amyloid (Abeta peptides. Yet conflicting data have been reported on the respective effect of cholesterol and glycosphingolipids (GSLs on the supramolecular assembly of Abeta peptides. The aim of the present study was to unravel the molecular mechanisms by which cholesterol modulates the interaction between Abeta(1-40 and chemically defined GSLs (GalCer, LacCer, GM1, GM3. Using the Langmuir monolayer technique, we show that Abeta(1-40 selectively binds to GSLs containing a 2-OH group in the acyl chain of the ceramide backbone (HFA-GSLs. In contrast, Abeta(1-40 did not interact with GSLs containing a nonhydroxylated fatty acid (NFA-GSLs. Cholesterol inhibited the interaction of Abeta(1-40 with HFA-GSLs, through dilution of the GSL in the monolayer, but rendered the initially inactive NFA-GSLs competent for Abeta(1-40 binding. Both crystallographic data and molecular dynamics simulations suggested that the active conformation of HFA-GSL involves a H-bond network that restricts the orientation of the sugar group of GSLs in a parallel orientation with respect to the membrane. This particular conformation is stabilized by the 2-OH group of the GSL. Correspondingly, the interaction of Abeta(1-40 with HFA-GSLs is strongly inhibited by NaF, an efficient competitor of H-bond formation. For NFA-GSLs, this is the OH group of cholesterol that constrains the glycolipid to adopt the active L-shape conformation compatible with sugar-aromatic CH-pi stacking interactions involving residue Y10 of Abeta(1-40. We conclude that cholesterol can either inhibit or facilitate membrane-Abeta interactions through fine tuning of glycosphingolipid conformation. These data shed some light on the complex molecular interplay between cell surface GSLs, cholesterol and Abeta peptides, and on the

  8. Activation of the endoplasmic reticulum stress response by the amyloid-beta 1-40 peptide in brain endothelial cells.

    Science.gov (United States)

    Fonseca, Ana Catarina R G; Ferreiro, Elisabete; Oliveira, Catarina R; Cardoso, Sandra M; Pereira, Cláudia F

    2013-12-01

    Neurovascular dysfunction arising from endothelial cell damage is an early pathogenic event that contributes to the neurodegenerative process occurring in Alzheimer's disease (AD). Since the mechanisms underlying endothelial dysfunction are not fully elucidated, this study was aimed to explore the hypothesis that brain endothelial cell death is induced upon the sustained activation of the endoplasmic reticulum (ER) stress response by amyloid-beta (Aβ) peptide, which deposits in the cerebral vessels in many AD patients and transgenic mice. Incubation of rat brain endothelial cells (RBE4 cell line) with Aβ1-40 increased the levels of several markers of ER stress-induced unfolded protein response (UPR), in a time-dependent manner, and affected the Ca(2+) homeostasis due to the release of Ca(2+) from this intracellular store. Finally, Aβ1-40 was shown to activate both mitochondria-dependent and -independent apoptotic cell death pathways. Enhanced release of cytochrome c from mitochondria and activation of the downstream caspase-9 were observed in cells treated with Aβ1-40 concomitantly with caspase-12 activation. Furthermore, Aβ1-40 activated the apoptosis effectors' caspase-3 and promoted the translocation of apoptosis-inducing factor (AIF) to the nucleus demonstrating the involvement of caspase-dependent and -independent mechanisms during Aβ-induced endothelial cell death. In conclusion, our data demonstrate that ER stress plays a significant role in Aβ1-40-induced apoptotic cell death in brain endothelial cells suggesting that ER stress-targeted therapeutic strategies might be useful in AD to counteract vascular defects and ultimately neurodegeneration. © 2013.

  9. Analysis of the complex between amyloid beta peptides and mitochondrial enzyme 17beta-HSD in cerebrospinal fluid

    Czech Academy of Sciences Publication Activity Database

    Krištofíková, Z.; Hegnerová, Kateřina; Bocková, Markéta; Vaisocherová, Hana; Bartoš, A.; Říčný, J.; Řípová, D.; Homola, J.

    2008-01-01

    Roč. 275, podzim (2008), s. 249-249 ISSN 1742-464X. [EUROPTRODE /9./. Dublin, 30.03.2008-02.04.2008] Institutional research plan: CEZ:AV0Z20670512 Keywords : surface plasmon resonance * alzheimer disease * 17beta-HSD10 Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 3.139, year: 2008

  10. Generation of the beta-amyloid peptide and the amyloid precursor protein C-terminal fragment gamma are potentiated by FE65L1.

    Science.gov (United States)

    Chang, Yang; Tesco, Giuseppina; Jeong, William J; Lindsley, Loren; Eckman, Elizabeth A; Eckman, Christopher B; Tanzi, Rudolph E; Guénette, Suzanne Y

    2003-12-19

    Members of the FE65 family of adaptor proteins, FE65, FE65L1, and FE65L2, bind the C-terminal region of the amyloid precursor protein (APP). Overexpression of FE65 and FE65L1 was previously reported to increase the levels of alpha-secretase-derived APP (APPs alpha). Increased beta-amyloid (A beta) generation was also observed in cells showing the FE65-dependent increase in APPs alpha. To understand the mechanism for the observed increase in both A beta and APPs alpha given that alpha-secretase cleavage of a single APP molecule precludes A beta generation, we examined the effects of FE65L1 overexpression on APP C-terminal fragments (APP CTFs). Our data show that FE65L1 potentiates gamma-secretase processing of APP CTFs, including the amyloidogenic CTF C99, accounting for the ability of FE65L1 to increase generation of APP C-terminal domain and A beta 40. The FE65L1 modulation of these processing events requires binding of FE65L1 to APP and APP CTFs and is not because of a direct effect on gamma-secretase activity, because Notch intracellular domain generation is not altered by FE65L1. Furthermore, enhanced APP CTF processing can be detected in early endosome vesicles but not in endoplasmic reticulum or Golgi membranes, suggesting that the effects of FE65L1 occur at or near the plasma membrane. Finally, although FE65L1 increases APP C-terminal domain production, it does not mediate the APP-dependent transcriptional activation observed with FE65.

  11. Inhibition of Alzheimer amyloid {beta} aggregation by polyvalent trehalose

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Yoshiko; You, Chouga [School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Ohnishi, Reiko [Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)], E-mail: miuray@jaist.ac.jp

    2008-04-15

    A glycopolymer carrying trehalose was found to suppress the formation of amyloid fibrils from the amyloid {beta} peptide (1-42) (A{beta}), as evaluated by thioflavin T assay and atomic force microscopy. Glycopolymers carrying sugar alcohols also changed the aggregation properties of A{beta}, and the inhibitory effect depended on the type of sugar and alkyl side chain. Neutralization activity was confirmed by in vitro assay using HeLa cells. The glycopolymer carrying trehalose strongly inhibited amyloid formation and neutralized cytotoxicity.

  12. A sensitive and selective electrochemical biosensor for the determination of beta-amyloid oligomer by inhibiting the peptide-triggered in situ assembly of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Xing Y

    2017-04-01

    Full Text Available Yun Xing,1,2 Xiao-Zhen Feng,2 Lipeng Zhang,1 Jiating Hou,2 Guo-Cheng Han,2 Zhencheng Chen2 1Henan Province of Key Laboratory of New Optoelectronic Functional Materials, College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, 2School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi, People’s Republic of China Abstract: Soluble beta-amyloid (Aβ oligomer is believed to be the most important toxic species in the brain of Alzheimer’s disease (AD patients. Thus, it is critical to develop a simple method for the selective detection of Aβ oligomer with low cost and high sensitivity. In this paper, we report an electrochemical method for the detection of Aβ oligomer with a peptide as the bioreceptor and silver nanoparticle (AgNP aggregates as the redox reporters. This strategy is based on the conversion of AgNP-based colorimetric assay into electrochemical analysis. Specifically, the peptide immobilized on the electrode surface and presented in solution triggered together the in situ formation of AgNP aggregates, which produced a well-defined electrochemical signal. However, the specific binding of Aβ oligomer to the immobilized peptide prevented the in situ assembly of AgNPs. As a result, a poor electrochemical signal was observed. The detection limit of the method was found to be 6 pM. Furthermore, the amenability of this method for the analysis of Aβ oligomer in serum and artificial cerebrospinal fluid (aCSF samples was demonstrated. Keywords: electrochemical biosensors, Alzheimer’s disease, beta-amyloid oligomer, peptide, silver nanoparticles

  13. Rosuvastatin ameliorates cognitive impairment in rats fed with high-salt and cholesterol diet via inhibiting acetylcholinesterase activity and amyloid beta peptide aggregation.

    Science.gov (United States)

    Husain, I; Akhtar, M; Abdin, M Zainul; Islamuddin, M; Shaharyar, M; Najmi, A K

    2018-04-01

    Amyloid beta (Aβ) peptide aggregation and cholinergic neurodegeneration are involved in the development of cognitive impairment. Therefore, in this article, we examined rosuvastatin (RSV), an oral hypolipidemic drug, to determine its potential as a dual inhibitor of acetylcholinesterase (AChE) and Aβ peptide aggregation for the treatment of cognitive impairment. Molecular docking study was done to examine the affinity of RSV with Aβ 1-42 and AChE in silico. We also employed neurobehavioral activity tests, biochemical estimation, and histopathology to study the anti-Aβ 1-42 aggregation capability of RSV in vivo. Molecular docking study provided evidence that RSV has the best binding conformer at its receptor site or active site of an enzyme. The cognitive impairment in female Wistar rats was induced by high-salt and cholesterol diet (HSCD) ad libitum for 8 weeks. RSV ameliorated serum cholesterol level, AChE activity, and Aβ 1-42 peptide aggregations in HSCD induced cognitive impairment. In addition, RSV-treated rats showed greater scores in the open field (locomotor activity) test. Moreover, the histopathological studies in the hippocampus and cortex of rat brain also supported that RSV markedly reduced the cognitive impairment and preserved the normal histoarchitectural pattern of the hippocampus and cortex. Taken together, these data indicate that RSV may act as a dual inhibitor of AChE and Aβ 1-42 peptide aggregation, therefore suggesting a therapeutic strategy for cognitive impairment treatment.

  14. Neurofibrillary tangles and the deposition of a beta amyloid peptide with a novel N-terminal epitope in the brains of wild Tsushima leopard cats.

    Directory of Open Access Journals (Sweden)

    James K Chambers

    Full Text Available Beta amyloid (Aβ deposits are seen in aged individuals in many of the mammalian species that possess the same Aβ amino acid sequence as humans. Conversely, neurofibrillary tangles (NFT, the other hallmark lesion of Alzheimer's disease (AD, are extremely rare in these animals. We detected Aβ deposits in the brains of Tsushima leopard cats (Prionailurus bengalensis euptilurus that live exclusively on Tsushima Island, Japan. Aβ42 was deposited in a granular pattern in the neuropil of the pyramidal cell layer, but did not form argyrophilic senile plaques. These Aβ deposits were not immunolabeled with antibodies to the N-terminal of human Aβ. Sequence analysis of the amyloid precursor protein revealed an amino acid substitution at the 7th residue of the Aβ peptide. In a comparison with other mammalian animals that do develop argyrophilic senile plaques, we concluded that the alternative Aβ amino acid sequence displayed by leopard cats is likely to be related to its distinctive deposition pattern. Interestingly, most of the animals with these Aβ deposits also developed NFTs. The distributions of hyperphosphorylated tau-positive cells and the two major isoforms of aggregated tau proteins were quite similar to those seen in Alzheimer's disease. In addition, the unphosphorylated form of GSK-3β colocalized with hyperphosphorylated tau within the affected neurons. In conclusion, this animal species develops AD-type NFTs without argyrophilic senile plaques.

  15. Accumulation of Exogenous Amyloid-Beta Peptide in Hippocampal Mitochondria Causes Their Dysfunction: A Protective Role for Melatonin

    Directory of Open Access Journals (Sweden)

    Sergio Rosales-Corral

    2012-01-01

    Full Text Available Amyloid-beta (Aβ pathology is related to mitochondrial dysfunction accompanied by energy reduction and an elevated production of reactive oxygen species (ROS. Monomers and oligomers of Aβ have been found inside mitochondria where they accumulate in a time-dependent manner as demonstrated in transgenic mice and in Alzheimer’s disease (AD brain. We hypothesize that the internalization of extracellular Aβ aggregates is the major cause of mitochondrial damage and here we report that following the injection of fibrillar Aβ into the hippocampus, there is severe axonal damage which is accompanied by the entrance of Aβ into the cell. Thereafter, Aβ appears in mitochondria where it is linked to alterations in the ionic gradient across the inner mitochondrial membrane. This effect is accompanied by disruption of subcellular structure, oxidative stress, and a significant reduction in both the respiratory control ratio and in the hydrolytic activity of ATPase. Orally administrated melatonin reduced oxidative stress, improved the mitochondrial respiratory control ratio, and ameliorated the energy imbalance.

  16. Zn(II)- and Cu(II)-induced non-fibrillar aggregates of amyloid-beta (1-42) peptide are transformed to amyloid fibrils, both spontaneously and under the influence of metal chelators.

    Science.gov (United States)

    Tõugu, Vello; Karafin, Ann; Zovo, Kairit; Chung, Roger S; Howells, Claire; West, Adrian K; Palumaa, Peep

    2009-09-01

    Aggregation of amyloid-beta (Abeta) peptides is a central phenomenon in Alzheimer's disease. Zn(II) and Cu(II) have profound effects on Abeta aggregation; however, their impact on amyloidogenesis is unclear. Here we show that Zn(II) and Cu(II) inhibit Abeta(42) fibrillization and initiate formation of non-fibrillar Abeta(42) aggregates, and that the inhibitory effect of Zn(II) (IC(50) = 1.8 micromol/L) is three times stronger than that of Cu(II). Medium and high-affinity metal chelators including metallothioneins prevented metal-induced Abeta(42) aggregation. Moreover, their addition to preformed aggregates initiated fast Abeta(42) fibrillization. Upon prolonged incubation the metal-induced aggregates also transformed spontaneously into fibrils, that appear to represent the most stable state of Abeta(42). H13A and H14A mutations in Abeta(42) reduced the inhibitory effect of metal ions, whereas an H6A mutation had no significant impact. We suggest that metal binding by H13 and H14 prevents the formation of a cross-beta core structure within region 10-23 of the amyloid fibril. Cu(II)-Abeta(42) aggregates were neurotoxic to neurons in vitro only in the presence of ascorbate, whereas monomers and Zn(II)-Abeta(42) aggregates were non-toxic. Disturbed metal homeostasis in the vicinity of zinc-enriched neurons might pre-dispose formation of metal-induced Abeta aggregates, subsequent fibrillization of which can lead to amyloid formation. The molecular background underlying metal-chelating therapies for Alzheimer's disease is discussed in this light.

  17. Amyloid-beta induced CA1 pyramidal cell loss in young adult rats is alleviated by systemic treatment with FGL, a neural cell adhesion molecule-derived mimetic peptide.

    Directory of Open Access Journals (Sweden)

    Nicola J Corbett

    Full Text Available Increased levels of neurotoxic amyloid-beta in the brain are a prominent feature of Alzheimer's disease. FG-Loop (FGL, a neural cell adhesion molecule-derived peptide that corresponds to its second fibronectin type III module, has been shown to provide neuroprotection against a range of cellular insults. In the present study impairments in social recognition memory were seen 24 days after a 5 mg/15 µl amyloid-beta(25-35 injection into the right lateral ventricle of the young adult rat brain. This impairment was prevented if the animal was given a systemic treatment of FGL. Unbiased stereology was used to investigate the ability of FGL to alleviate the deleterious effects on CA1 pyramidal cells of the amyloid-beta(25-35 injection. NeuN, a neuronal marker (for nuclear staining was used to identify pyramidal cells, and immunocytochemistry was also used to identify inactive glycogen synthase kinase 3beta (GSK3β and to determine the effects of amyloid-beta(25-35 and FGL on the activation state of GSK3β, since active GSK3β has been shown to cause a range of AD pathologies. The cognitive deficits were not due to hippocampal atrophy as volume estimations of the entire hippocampus and its regions showed no significant loss, but amyloid-beta caused a 40% loss of pyramidal cells in the dorsal CA1 which was alleviated partially by FGL. However, FGL treatment without amyloid-beta was also found to cause a 40% decrease in CA1 pyramidal cells. The action of FGL may be due to inactivation of GSK3β, as an increased proportion of CA1 pyramidal neurons contained inactive GSK3β after FGL treatment. These data suggest that FGL, although potentially disruptive in non-pathological conditions, can be neuroprotective in disease-like conditions.

  18. Proposal for novel curcumin derivatives as potent inhibitors against Alzheimer's disease: Ab initio molecular simulations on the specific interactions between amyloid-beta peptide and curcumin

    Science.gov (United States)

    Ota, Shintaro; Fujimori, Mitsuki; Ishimura, Hiromi; Shulga, Sergiy; Kurita, Noriyuki

    2017-10-01

    Accumulation of amyloid-β (Aβ) peptides in a brain is closely related with the pathogenesis of Alzheimer's disease. To suppress the production of Aβ peptides, we propose novel curcumin derivatives and investigate their binding properties with the amyloid precursor protein (APP), using protein-ligand docking as well as ab initio molecular simulations. Our proposed derivative (curcumin XIV) is found to have a large binding energy with APP and interacts strongly with the cleavage site Ala19 by secretase. It is thus expected that curcumin XIV can protect APP from the secretase attack and be a potent inhibitor against the production of Aβ peptides.

  19. Cysteine Cathepsins in the secretory vesicle produce active peptides: Cathepsin L generates peptide neurotransmitters and cathepsin B produces beta-amyloid of Alzheimer's disease.

    Science.gov (United States)

    Hook, Vivian; Funkelstein, Lydiane; Wegrzyn, Jill; Bark, Steven; Kindy, Mark; Hook, Gregory

    2012-01-01

    Recent new findings indicate significant biological roles of cysteine cathepsin proteases in secretory vesicles for production of biologically active peptides. Notably, cathepsin L in secretory vesicles functions as a key protease for proteolytic processing of proneuropeptides (and prohormones) into active neuropeptides that are released to mediate cell-cell communication in the nervous system for neurotransmission. Moreover, cathepsin B in secretory vesicles has been recently identified as a β-secretase for production of neurotoxic β- amyloid (Aβ) peptides that accumulate in Alzheimer's disease (AD), participating as a notable factor in the severe memory loss in AD. These secretory vesicle functions of cathepsins L and B for production of biologically active peptides contrast with the well-known role of cathepsin proteases in lysosomes for the degradation of proteins to result in their inactivation. The unique secretory vesicle proteome indicates proteins of distinct functional categories that provide the intravesicular environment for support of cysteine cathepsin functions. Features of the secretory vesicle protein systems insure optimized intravesicular conditions that support the proteolytic activity of cathepsins. These new findings of recently discovered biological roles of cathepsins L and B indicate their significance in human health and disease. This article is part of a Special Issue entitled: Proteolysis 50 years after the discovery of lysosome. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Other Species in the Aqueous Environment of a Peptide Can Invert its Intrinsic Solvated Polyproline II/Beta Propensity: Implications for Amyloid Formation.

    Science.gov (United States)

    Mirkin, Noemi G; Krimm, Samuel

    2016-02-02

    As we have previously shown, the predominance of the polyproline II conformation in the circular dichroism spectra of aqueous polypeptides is related to its lower energy than that of the beta conformation. In order to test whether this is still the case in the presence of additional components in the medium, we have calculated the energy difference between these two conformations in an alanine-dipeptide/twelve-water system without and with the addition of an HCl molecule. We find in the latter case that the beta conformer is of lower energy than the polyproline II. Energy profiles near the minima in both cases also permit conclusions about the relative entropies of these structures. These results emphasize the importance of considering the peptide-plus-medium state as the relevant entity in determining the structural properties of such systems. Such an inversion could be relevant to the formation of amyloid and could thus lead to new strategies for studying its role in the development of neurodegenerative diseases. This article is protected by copyright. All rights reserved. © 2016 Wiley Periodicals, Inc.

  1. The Na+/K+-ATPase and the amyloid-beta peptide aβ1-40 control the cellular distribution, abundance and activity of TRPC6 channels.

    Science.gov (United States)

    Chauvet, Sylvain; Boonen, Marielle; Chevallet, Mireille; Jarvis, Louis; Abebe, Addis; Benharouga, Mohamed; Faller, Peter; Jadot, Michel; Bouron, Alexandre

    2015-11-01

    The Na(+)/K(+)-ATPase interacts with the non-selective cation channels TRPC6 but the functional consequences of this association are unknown. Experiments performed with HEK cells over-expressing TRPC6 channels showed that inhibiting the activity of the Na(+)/K(+)-ATPase with ouabain reduced the amount of TRPC6 proteins and depressed Ca(2+) entry through TRPC6. This effect, not mimicked by membrane depolarization with KCl, was abolished by sucrose and bafilomycin-A, and was partially sensitive to the intracellular Ca(2+) chelator BAPTA/AM. Biotinylation and subcellular fractionation experiments showed that ouabain caused a multifaceted redistribution of TRPC6 to the plasma membrane and to an endo/lysosomal compartment where they were degraded. The amyloid beta peptide Aβ(1-40), another inhibitor of the Na(+)/K(+)-ATPase, but not the shorter peptide Aβ1-16, reduced TRPC6 protein levels and depressed TRPC6-mediated responses. In cortical neurons from embryonic mice, ouabain, veratridine (an opener of voltage-gated Na(+) channel), and Aβ(1-40) reduced TRPC6-mediated Ca(2+) responses whereas Aβ(1-16) was ineffective. Furthermore, when Aβ(1-40) was co-added together with zinc acetate it could no longer control TRPC6 activity. Altogether, this work shows the existence of a functional coupling between the Na(+)/K(+)-ATPase and TRPC6. It also suggests that the abundance, distribution and activity of TRPC6 can be regulated by cardiotonic steroids like ouabain and the naturally occurring peptide Aβ(1-40) which underlines the pathophysiological significance of these processes. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Small heat shock protein HspB8: its distribution in Alzheimer's disease brains and its inhibition of amyloid-beta protein aggregation and cerebrovascular amyloid-beta toxicity.

    NARCIS (Netherlands)

    Wilhelmus, M.M.M.; Boelens, W.C.; Otte-Holler, I.; Kamps, B.; Kusters, B.; Maat-Schieman, M.L.; Waal, R.M.W. de; Verbeek, M.M.

    2006-01-01

    Alzheimer's disease (AD) is characterized by pathological lesions, such as senile plaques (SPs) and cerebral amyloid angiopathy (CAA), both predominantly consisting of a proteolytic cleavage product of the amyloid-beta precursor protein (APP), the amyloid-beta peptide (Abeta). CAA is also the major

  3. Hyperforin prevents beta-amyloid neurotoxicity and spatial memory impairments by disaggregation of Alzheimer's amyloid-beta-deposits.

    Science.gov (United States)

    Dinamarca, M C; Cerpa, W; Garrido, J; Hancke, J L; Inestrosa, N C

    2006-11-01

    The major protein constituent of amyloid deposits in Alzheimer's disease (AD) is the amyloid beta-peptide (Abeta). In the present work, we have determined the effect of hyperforin an acylphloroglucinol compound isolated from Hypericum perforatum (St John's Wort), on Abeta-induced spatial memory impairments and on Abeta neurotoxicity. We report here that hyperforin: (1) decreases amyloid deposit formation in rats injected with amyloid fibrils in the hippocampus; (2) decreases the neuropathological changes and behavioral impairments in a rat model of amyloidosis; (3) prevents Abeta-induced neurotoxicity in hippocampal neurons both from amyloid fibrils and Abeta oligomers, avoiding the increase in reactive oxidative species associated with amyloid toxicity. Both effects could be explained by the capacity of hyperforin to disaggregate amyloid deposits in a dose and time-dependent manner and to decrease Abeta aggregation and amyloid formation. Altogether these evidences suggest that hyperforin may be useful to decrease amyloid burden and toxicity in AD patients, and may be a putative therapeutic agent to fight the disease.

  4. Kinetically controlled thermal response of beta2-microglobulin amyloid fibrils.

    Science.gov (United States)

    Sasahara, Kenji; Naiki, Hironobu; Goto, Yuji

    2005-09-23

    Calorimetric measurements were carried out using a differential scanning calorimeter in the temperature range from 10 to 120 degrees C for characterizing the thermal response of beta2-microglobulin amyloid fibrils. The thermograms of amyloid fibril solution showed a remarkably large decrease in heat capacity that was essentially released upon the thermal unfolding of the fibrils, in which the magnitude of negative heat capacity change was not explicable in terms of the current accessible surface area model of protein structural thermodynamics. The heat capacity-temperature curve of amyloid fibrils prior to the fibril unfolding exhibited an unusual dependence on the fibril concentration and the heating rate. Particularly, the heat needed to induce the thermal response was found to be linearly dependent on the heating rate, indicating that its thermal response is under a kinetic control and precluding the interpretation in terms of equilibrium thermodynamics. Furthermore, amyloid fibrils of amyloid beta peptides also exhibited a heating rate-dependent exothermic process before the fibril unfolding, indicating that the kinetically controlled thermal response may be a common phenomenon to amyloid fibrils. We suggest that the heating rate-dependent negative change in heat capacity is coupled to the association of amyloid fibrils with characteristic hydration pattern.

  5. Mutation-based structural modification and dynamics study of amyloid beta peptide (1–42: An in-silico-based analysis to cognize the mechanism of aggregation

    Directory of Open Access Journals (Sweden)

    Pritam Kumar Panda

    2016-03-01

    Full Text Available Alzheimer's disease is the prevalent cause of premature senility, a progressive mental disorder due to degeneration in brain and deposition of amyloid β peptide (1–42, a misfolded protein in the form of aggregation that prevails for a prolonged time and obstructs every aspect of life. One of the primary hallmarks of the neuropathological disease is the accretion of amyloid β peptide in the brain that leads to Alzheimer's disease, but the mechanism is still a mystery. Several investigations have shown that mutations at specific positions have a significant impact in stability of the peptide as predicted from aggregation profiles. Here in our study, we have analyzed the mutations by substituting residues at position A22G, E22G, E22K, E22Q, D23N, L34V and molecular dynamics have been performed to check the deviation in stability and conformation of the peptide. The results validated that the mutations at specific positions lead to instability and the proline substitution at E22P and L34P stalled the aggregation of the peptide. Keywords: Amyloid β peptide, Alzheimer's disease, Aggregation, Mutational analysis, NAMD, UCSF Chimera, Discovery Studio Visualizer

  6. Monodisperse carboxyl-functionalized poly(ethylene glycol)-coated magnetic poly(glycidyl methacrylate) microspheres: application to the immunocapture of .beta.-amyloid peptides

    Czech Academy of Sciences Publication Activity Database

    Horák, Daniel; Hlídková, Helena; Hiraoui, M.; Taverna, M.; Proks, Vladimír; Mázl Chánová, Eliška; Smadja, C.; Kučerová, Z.

    2014-01-01

    Roč. 14, č. 11 (2014), s. 1590-1599 ISSN 1616-5187 R&D Projects: GA MŠk 7E12053 EU Projects: European Commission(XE) 246513 - NADINE Institutional support: RVO:61389013 Keywords : β-amyloid peptides * CE-LIF detection * functionalization Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.851, year: 2014

  7. Amyloid fibril formation from sequences of a natural beta-structured fibrous protein, the adenovirus fiber.

    Science.gov (United States)

    Papanikolopoulou, Katerina; Schoehn, Guy; Forge, Vincent; Forsyth, V Trevor; Riekel, Christian; Hernandez, Jean-François; Ruigrok, Rob W H; Mitraki, Anna

    2005-01-28

    Amyloid fibrils are fibrous beta-structures that derive from abnormal folding and assembly of peptides and proteins. Despite a wealth of structural studies on amyloids, the nature of the amyloid structure remains elusive; possible connections to natural, beta-structured fibrous motifs have been suggested. In this work we focus on understanding amyloid structure and formation from sequences of a natural, beta-structured fibrous protein. We show that short peptides (25 to 6 amino acids) corresponding to repetitive sequences from the adenovirus fiber shaft have an intrinsic capacity to form amyloid fibrils as judged by electron microscopy, Congo Red binding, infrared spectroscopy, and x-ray fiber diffraction. In the presence of the globular C-terminal domain of the protein that acts as a trimerization motif, the shaft sequences adopt a triple-stranded, beta-fibrous motif. We discuss the possible structure and arrangement of these sequences within the amyloid fibril, as compared with the one adopted within the native structure. A 6-amino acid peptide, corresponding to the last beta-strand of the shaft, was found to be sufficient to form amyloid fibrils. Structural analysis of these amyloid fibrils suggests that perpendicular stacking of beta-strand repeat units is an underlying common feature of amyloid formation.

  8. The amyloid beta-peptide is imported into mitochondria via the TOM import machinery and localized to mitochondrial cristae

    DEFF Research Database (Denmark)

    Hansson Petersen, Camilla A; Alikhani, Nyosha; Behbahani, Homira

    2008-01-01

    that extracellulary applied Abeta can be internalized by human neuroblastoma cells and can colocalize with mitochondrial markers. Together, these results provide further insight into the mitochondrial uptake of Abeta, a peptide considered to be of major significance in Alzheimer's disease....

  9. Timing of neurodegeneration and beta-amyloid (Abeta) peptide deposition in the brain of aging kokanee salmon.

    Science.gov (United States)

    Maldonado, Tammy A; Jones, Richard E; Norris, David O

    2002-10-01

    Brains of kokanee salmon (Oncorhynchus nerka kennerlyi) in one of four reproductive stages (sexually immature, maturing, sexually mature, and spawning) were stained with cresyl violet and silver stain to visualize neurodegeneration. These reproductive stages correlate with increasing somatic aging of kokanee salmon, which die after spawning. Twenty-four regions of each brain were examined. Brains of sexually immature fish exhibited low levels of neurodegeneration, whereas neurodegeneration was more marked in maturing fish and greatest in spawning fish. Neurodegeneration was present in specific regions of the telencephalon, diencephalon, mesencephalon, and rhombencephalon. Pyknotic neurons were observed in all regions previously reported to be immunopositive for A beta. Regions that did not exhibit neurodegeneration during aging included the magnocellular vestibular nucleus, the nucleus lateralis tuberis of the hypothalamus, and Purkinje cells of the cerebellum, all of which also lack A beta; perhaps these regions are neuroprotected. In 14 of 16 brain areas for which data were available on both the increase in A beta deposition and pyknosis, neurodegeneration preceded or appeared more or less simultaneously with A beta production, whereas in only two regions did A beta deposition precede neurodegeneration. This information supports the hypothesis that A beta deposition is a downstream product of neurodegeneration in most brain regions. Other conclusions are that the degree of neurodegeneration varies among brain regions, neurodegeneration begins in maturing fish and peaks in spawning fish, the timing of neurodegeneration varies among brain regions, and some regions do not exhibit accelerated neurodegeneration during aging. Copyright 2002 Wiley Periodicals, Inc.

  10. Surface Mediated Self-Assembly of Amyloid Peptides

    Science.gov (United States)

    Fakhraai, Zahra

    2015-03-01

    Amyloid fibrils have been considered as causative agents in many neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, type II diabetes and amyloidosis. Amyloid fibrils form when proteins or peptides misfold into one dimensional crystals of stacked beta-sheets. In solution, amyloid fibrils form through a nucleation and growth mechanism. The rate limiting nucleation step requires a critical concentration much larger than those measured in physiological conditions. As such the exact origins of the seeds or oligomers that result in the formation of fully mature fibrils in the body remain topic intense studies. It has been suggested that surfaces and interfaces can enhance the fibrillization rate. However, studies of the mechanism and kinetics of the surface-mediated fibrillization are technologically challenging due to the small size of the oligomer and protofibril species. Using smart sample preparation technique to dry the samples after various incubation times we are able to study the kinetics of fibril formation both in solution and in the vicinity of various surfaces using high-resolution atomic force microscopy. These studies elucidate the role of surfaces in catalyzing amyloid peptide formation through a nucleation-free process. The nucleation free self-assembly is rapid and requires much smaller concentrations of peptides or proteins. We show that this process resembles diffusion limited aggregation and is governed by the peptide adhesion rate, two -dimensional diffusion of the peptides on the surface, and preferential interactions between the peptides. These studies suggest an alternative pathway for amyloid formation may exist, which could lead to new criteria for disease prevention and alternative therapies. Research was partially supported by a seed grant from the National Institute of Aging of the National Institutes of Health (NIH) under Award Number P30AG010124 (PI: John Trojanowski) and the University of Pennsylvania.

  11. Halogenation dictates the architecture of amyloid peptide nanostructures.

    Science.gov (United States)

    Pizzi, Andrea; Pigliacelli, Claudia; Gori, Alessandro; Nonappa; Ikkala, Olli; Demitri, Nicola; Terraneo, Giancarlo; Castelletto, Valeria; Hamley, Ian W; Baldelli Bombelli, Francesca; Metrangolo, Pierangelo

    2017-07-20

    Amyloid peptides yield a plethora of interesting nanostructures though difficult to control. Here we report that depending on the number, position, and nature of the halogen atoms introduced into either one or both phenylalanine benzene rings of the amyloid β peptide-derived core-sequence KLVFF, four different architectures were obtained in a controlled manner. Our findings demonstrate that halogenation may develop as a general strategy to engineer amyloidal peptide self-assembly and obtain new amyloidal nanostructures.

  12. Reducing the Levels of Akt Activation by PDK1 Knock-in Mutation Protects Neuronal Cultures against Synthetic Amyloid-Beta Peptides

    Directory of Open Access Journals (Sweden)

    Shaobin Yang

    2018-01-01

    Full Text Available The Akt kinase has been widely assumed for years as a key downstream effector of the PI3K signaling pathway in promoting neuronal survival. This notion was however challenged by the finding that neuronal survival responses were still preserved in mice with reduced Akt activity. Moreover, here we show that the Akt signaling is elevated in the aged brain of two different mice models of Alzheimer Disease. We manipulate the rate of Akt stimulation by employing knock-in mice expressing a mutant form of PDK1 (phosphoinositide-dependent protein kinase 1 with reduced, but not abolished, ability to activate Akt. We found increased membrane localization and activity of the TACE/ADAM17 α-secretase in the brain of the PDK1 mutant mice with concomitant TNFR1 processing, which provided neurons with resistance against TNFα-induced neurotoxicity. Opposite to the Alzheimer Disease transgenic mice, the PDK1 knock-in mice exhibited an age-dependent attenuation of the unfolding protein response, which protected the mutant neurons against endoplasmic reticulum stressors. Moreover, these two mechanisms cooperatively provide the mutant neurons with resistance against amyloid-beta oligomers, and might singularly also contribute to protect these mice against amyloid-beta pathology.

  13. Beta-amyloid and cholinergic neurons

    Czech Academy of Sciences Publication Activity Database

    Doležal, Vladimír; Kašparová, Jana

    2003-01-01

    Roč. 28, 3-4 (2003), s. 499-506 ISSN 0364-3190 R&D Projects: GA ČR GA305/01/0283; GA AV ČR IAA5011206 Institutional research plan: CEZ:AV0Z5011922 Keywords : cholinergic neurons * AlzheimerŽs disease * beta-amyloid Subject RIV: FH - Neurology Impact factor: 1.511, year: 2003

  14. An UHPLC-MS/MS method for simultaneous quantification of human amyloid beta peptides Aβ1-38, Aβ1-40 and Aβ1-42 in cerebrospinal fluid using micro-elution solid phase extraction.

    Science.gov (United States)

    Lin, Ping-Ping; Chen, Wei-Li; Yuan, Fei; Sheng, Lei; Wu, Yu-Jia; Zhang, Wei-Wei; Li, Guo-Qing; Xu, Hong-Rong; Li, Xue-Ning

    2017-12-01

    Amyloid beta (Aβ) peptides in cerebrospinal fluid are extensively estimated for identification of Alzheimer's disease (AD) as diagnostic biomarkers. Unfortunately, their pervasive application is hampered by interference from Aβ propensity of self-aggregation, nonspecifically bind to surfaces and matrix proteins, and by lack of quantitive standardization. Here we report on an alternative Ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous measurement of human amyloid beta peptides Aβ1-38, Aβ1-40 and Aβ1-42 in cerebrospinal fluid (CSF) using micro-elution solid phase extraction (SPE). Samples were pre-processing by the mixed-mode micro-elution solid phase extraction and quantification was performed in the positive ion multiple reaction monitoring (MRM) mode using electrospray ionization. The stable-isotope labeled Aβ peptides 15 N 51 - Aβ1-38, 15 N 53 - Aβ1-40 and 15 N 55 - Aβ1-42 peptides were used as internal standards. And the artificial cerebrospinal fluid (ACSF) containing 5% rat plasma was used as a surrogate matrix for calibration curves. The quality control (QC) samples at 0.25, 2 and 15ng/mL were prepared. A "linear" regression (1/x 2 weighting): y=ax+b was used to fit the calibration curves over the concentration range of 0.1-20ng/mL for all three peptides. Coefficient of variation (CV) of intra-batch and inter-batch assays were all less than 6.44% for Aβ1-38, 6.75% for Aβ1-40 and 10.74% for Aβ1-42. The precision values for all QC samples of three analytes met the acceptance criteria. Extract recoveries of Aβ1-38, Aβ1-40 and Aβ1-42 were all greater than 70.78%, both in low and high QC samples. The stability assessments showed that QC samples at both low and high levels could be stable for at least 24h at 4°C, 4h at room temperature and through three freeze-thaw cycles without sacrificing accuracy or precision. And no significant carryover effect was observed. This validated UHPLC

  15. Evidence for novel beta-sheet structures in Iowa mutant beta-amyloid fibrils.

    Science.gov (United States)

    Tycko, Robert; Sciarretta, Kimberly L; Orgel, Joseph P R O; Meredith, Stephen C

    2009-07-07

    Asp23-to-Asn mutation within the coding sequence of beta-amyloid, called the Iowa mutation, is associated with early onset, familial Alzheimer's disease and cerebral amyloid angiopathy, in which patients develop neuritic plaques and massive vascular deposition predominantly of the mutant peptide. We examined the mutant peptide, D23N-Abeta40, by electron microscopy, X-ray diffraction, and solid-state NMR spectroscopy. D23N-Abeta40 forms fibrils considerably faster than the wild-type peptide (k = 3.77 x 10(-3) min(-1) and 1.07 x 10(-4) min(-1) for D23N-Abeta40 and the wild-type peptide WT-Abeta40, respectively) and without a lag phase. Electron microscopy shows that D23N-Abeta40 forms fibrils with multiple morphologies. X-ray fiber diffraction shows a cross-beta pattern, with a sharp reflection at 4.7 A and a broad reflection at 9.4 A, which is notably smaller than the value for WT-Abeta40 fibrils (10.4 A). Solid-state NMR measurements indicate molecular level polymorphism of the fibrils, with only a minority of D23N-Abeta40 fibrils containing the in-register, parallel beta-sheet structure commonly found in WT-Abeta40 fibrils and most other amyloid fibrils. Antiparallel beta-sheet structures in the majority of fibrils are indicated by measurements of intermolecular distances through (13)C-(13)C and (15)N-(13)C dipole-dipole couplings. An intriguing possibility exists that there is a relationship between the aberrant structure of D23N-Abeta40 fibrils and the unusual vasculotropic clinical picture in these patients.

  16. Disrupting beta-amyloid aggregation for Alzheimer disease treatment.

    Science.gov (United States)

    Estrada, L D; Soto, C

    2007-01-01

    Alzheimer's disease is a devastating degenerative disorder for which there is no cure or effective treatment. Although the etiology of Alzheimer's disease is not fully understood, compelling evidence indicates that deposition of aggregates composed by a misfolded form of the amyloid beta peptide (Abeta) is the central event in the disease pathogenesis. Therefore, an attractive therapeutic strategy is to prevent or reverse Abeta misfolding and aggregation. Diverse strategies have been described to identify inhibitors of this process, including screening of libraries of small molecules chemical compounds, rational design of synthetic peptides, assessment of natural Abeta-binding proteins and stimulation of the immune system by vaccination. In this article we describe these different approaches, their principles and their potential strengths and weaknesses. Overall the available data suggest that the development of drugs to interfere with Abeta misfolding and aggregation is a feasible target that hold great promise for the treatment of Alzheimer's disease.

  17. Some commonly used brominated flame retardants cause Ca2+-ATPase inhibition, beta-amyloid peptide release and apoptosis in SH-SY5Y neuronal cells.

    Directory of Open Access Journals (Sweden)

    Fawaz Al-Mousa

    Full Text Available Brominated flame retardants (BFRs are chemicals commonly used to reduce the flammability of consumer products and are considered pollutants since they have become widely dispersed throughout the environment and have also been shown to bio-accumulate within animals and man. This study investigated the cytotoxicity of some of the most commonly used groups of BFRs on SH-SY5Y human neuroblastoma cells. The results showed that of the BFRs tested, hexabromocyclododecane (HBCD, tetrabromobisphenol-A (TBBPA and decabromodiphenyl ether (DBPE, all are cytotoxic at low micromolar concentrations (LC(50 being 2.7 ± 0.7 µM, 15 ± 4 µM and 28 ± 7 µM, respectively. They induced cell death, at least in part, by apoptosis through activation of caspases. They also increased intracellular [Ca(2+] levels and reactive-oxygen-species within these neuronal cells. Furthermore, these BFRs also caused rapid depolarization of the mitochondria and cytochrome c release in these neuronal cells. Elevated intracellular [Ca(2+] levels appear to occur through a mechanism involving microsomal Ca(2+-ATPase inhibition and this maybe responsible for Ca(2+-induced mitochondrial dysfunction. In addition, µM levels of these BFRs caused β-amyloid peptide (Aβ-42 processing and release from these cells with a few hours of exposure. These results therefore shows that these pollutants are both neurotoxic and amyloidogenic in-vitro.

  18. Covalent modifications of the amyloid beta peptide by hydroxynonenal: Effects on metal ion binding by monomers and insights into the fibril topology.

    Science.gov (United States)

    Grasso, G; Komatsu, H; Axelsen, P H

    2017-09-01

    Amyloid β peptides (Aβ) and metal ions are associated with oxidative stress in Alzheimer's disease (AD). Oxidative stress, acting on ω-6 polyunsaturated fatty acyl chains, produces diverse products, including 4-hydroxy-2-nonenal (HNE), which can covalently modify the Aβ that helped to produce it. To examine possible feedback mechanisms involving Aβ, metal ions and HNE production, the effects of HNE modification and fibril formation on metal ion binding was investigated. Results indicate that copper(II) generally inhibits the modification of His side chains in Aβ by HNE, but that once modified, copper(II) still binds to Aβ with high affinity. Fibril formation protects only one of the three His residues in Aβ from HNE modification, and this protection is consistent with proposed models of fibril structure. These results provide insight into a network of biochemical reactions that may be operating as a consequence of oxidative stress in AD, or as part of the pathogenic process. Copyright © 2016. Published by Elsevier Inc.

  19. BETASCAN: probable beta-amyloids identified by pairwise probabilistic analysis.

    Directory of Open Access Journals (Sweden)

    Allen W Bryan

    2009-03-01

    Full Text Available Amyloids and prion proteins are clinically and biologically important beta-structures, whose supersecondary structures are difficult to determine by standard experimental or computational means. In addition, significant conformational heterogeneity is known or suspected to exist in many amyloid fibrils. Recent work has indicated the utility of pairwise probabilistic statistics in beta-structure prediction. We develop here a new strategy for beta-structure prediction, emphasizing the determination of beta-strands and pairs of beta-strands as fundamental units of beta-structure. Our program, BETASCAN, calculates likelihood scores for potential beta-strands and strand-pairs based on correlations observed in parallel beta-sheets. The program then determines the strands and pairs with the greatest local likelihood for all of the sequence's potential beta-structures. BETASCAN suggests multiple alternate folding patterns and assigns relative a priori probabilities based solely on amino acid sequence, probability tables, and pre-chosen parameters. The algorithm compares favorably with the results of previous algorithms (BETAPRO, PASTA, SALSA, TANGO, and Zyggregator in beta-structure prediction and amyloid propensity prediction. Accurate prediction is demonstrated for experimentally determined amyloid beta-structures, for a set of known beta-aggregates, and for the parallel beta-strands of beta-helices, amyloid-like globular proteins. BETASCAN is able both to detect beta-strands with higher sensitivity and to detect the edges of beta-strands in a richly beta-like sequence. For two proteins (Abeta and Het-s, there exist multiple sets of experimental data implying contradictory structures; BETASCAN is able to detect each competing structure as a potential structure variant. The ability to correlate multiple alternate beta-structures to experiment opens the possibility of computational investigation of prion strains and structural heterogeneity of amyloid

  20. Amyloid-beta aggregates cause alterations of astrocytic metabolic phenotype: impact on neuronal viability

    OpenAIRE

    Allaman, Igor; Gavillet, Mathilde; Bélanger, Mireille; Laroche, Thierry; Viertl, David; Lashuel, Hilal A.; Magistretti, Pierre J.

    2010-01-01

    Amyloid-beta (Abeta) peptides play a key role in the pathogenesis of Alzheimer's disease and exert various toxic effects on neurons; however, relatively little is known about their influence on glial cells. Astrocytes play a pivotal role in brain homeostasis, contributing to the regulation of local energy metabolism and oxidative stress defense, two aspects of importance for neuronal viability and function. In the present study, we explored the effects of Abeta peptides on glucose metabolism ...

  1. alpha7 Nicotinic acetylcholine receptor knockout selectively enhances ethanol-, but not beta-amyloid-induced neurotoxicity.

    Science.gov (United States)

    de Fiebre, Nancyellen C; de Fiebre, Christopher M

    2005-01-03

    The alpha7 subtype of nicotinic acetylcholine receptor (nAChR) has been implicated as a potential site of action for two neurotoxins, ethanol and the Alzheimer's disease related peptide, beta-amyloid. Here, we utilized primary neuronal cultures of cerebral cortex from alpha7 nAChR null mutant mice to examine the role of this receptor in modulating the neurotoxic properties of subchronic, "binge" ethanol and beta-amyloid. Knockout of the alpha7 nAChR gene selectively enhanced ethanol-induced neurotoxicity in a gene dosage-related fashion. Susceptibility of cultures to beta-amyloid induced toxicity, however, was unaffected by alpha7 nAChR gene null mutation. Further, beta-amyloid did not inhibit the binding of the highly alpha7-selective radioligand, [(125)I]alpha-bungarotoxin. On the other hand, in studies in Xenopus oocytes ethanol efficaciously inhibited alpha7 nAChR function. These data suggest that alpha7 nAChRs modulate the neurotoxic effects of binge ethanol, but not the neurotoxicity produced by beta-amyloid. It is hypothesized that inhibition of alpha7 nAChRs by ethanol provides partial protection against the neurotoxic properties of subchronic ethanol.

  2. Quantitation of amyloid beta peptides Aβ(1-38), Aβ(1-40), and Aβ(1-42) in human cerebrospinal fluid by ultra-performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Lame, Mary E; Chambers, Erin E; Blatnik, Matthew

    2011-12-15

    Critical events in Alzheimer's disease (AD) involve an imbalance between the production and clearance of amyloid beta (Aβ) peptides from the brain. Current methods for Aβ quantitation rely heavily on immuno-based techniques. However, these assays require highly specific antibodies and reagents that are time-consuming and expensive to develop. Immuno-based assays are also characterized by poor dynamic ranges, cross-reactivity, matrix interferences, and dilution linearity problems. In particular, noncommercial immunoassays are especially subject to high intra- and interassay variability because they are not subject to more stringent manufacturing controls. Combinations of these factors make immunoassays more labor-intensive and often challenging to validate in support of clinical studies. Here we describe a mixed-mode solid-phase extraction method and an ultra-performance liquid chromatography tandem mass spectrometry (SPE UPLC-MS/MS) assay for the simultaneous quantitation of Aβ(1-38), Aβ(1-40), and Aβ(1-42) from human cerebrospinal fluid (CSF). Negative ion versus positive ion species were compared using their corresponding multiple reaction monitoring (MRM) transitions, and negative ions were approximately 1.6-fold greater in intensity but lacked selectivity in matrix. The positive ion MRM assay was more than sufficient to quantify endogenous Aβ peptides. Aβ standards were prepared in artificial CSF containing 5% rat plasma, and quality control samples were prepared in three pooled CSF sources. Extraction efficiency was greater than 80% for all three peptides, and the coefficient of variation during analysis was less than 15% for all species. Mean basal levels of Aβ species from three CSF pools were 1.64, 2.17, and 1.26 ng/ml for Aβ(1-38); 3.24, 3.63, and 2.55 ng/ml for Aβ(1-40); and 0.50, 0.63, and 0.46 ng/ml for Aβ(1-42). Copyright © 2011 Elsevier Inc. All rights reserved.

  3. Aggregation properties of a short peptide that mediates amyloid fibril ...

    Indian Academy of Sciences (India)

    Short peptides have been identified from amyloidogenic proteins that form amyloid fibrils in isolation. The ... proteins. These peptide fibrils have the conformational features of β-structure that .... water and immediately deposited on freshly cleaved surface of mica .... with the peptide via electrostatic interactions. NaCl would.

  4. A Peptide-Fc Opsonin with Pan-Amyloid Reactivity

    Directory of Open Access Journals (Sweden)

    James S. Foster

    2017-09-01

    Full Text Available There is a continuing need for therapeutic interventions for patients with the protein misfolding disorders that result in systemic amyloidosis. Recently, specific antibodies have been employed to treat AL amyloidosis by opsonizing tissue amyloid deposits thereby inducing cell-mediated dissolution and organ improvement. To develop a pan-amyloid therapeutic agent, we have produced an Fc-fusion product incorporating a peptide, p5, which binds many if not all forms of amyloid. This protein, designated Fcp5, expressed in mammalian cells, forms the desired bivalent dimer structure and retains pan-amyloid reactivity similar to the p5 peptide as measured by immunosorbent assays, immunohistochemistry, surface plasmon resonance, and pulldown assays using radioiodinated Fcp5. Additionally, Fcp5 was capable of opsonizing amyloid fibrils in vitro using a pH-sensitive fluorescence assay of phagocytosis. In mice,125 I-labeled Fcp5 exhibited an extended serum circulation time, relative to the p5 peptide. It specifically bound AA amyloid deposits in diseased mice, as evidenced by biodistribution and microautoradiographic methods, which coincided with an increase in active, Iba-1-positive macrophages in the liver at 48 h postinjection of Fcp5. In healthy mice, no specific tissue accumulation was observed. The data indicate that polybasic, pan-amyloid-targeting peptides, in the context of an Fc fusion, can yield amyloid reactive, opsonizing reagents that may serve as next-generation immunotherapeutics.

  5. Perforin Promotes Amyloid Beta Internalisation in Neurons.

    Science.gov (United States)

    Lana, Erica; Khanbolouki, Mahbod; Degavre, Charline; Samuelsson, Eva-Britt; Åkesson, Elisabet; Winblad, Bengt; Alici, Evren; Lithner, Christina Unger; Behbahani, Homira

    2017-03-01

    Studies on the mechanisms of neuronal amyloid-β (Aβ) internalisation are crucial for understanding the neuropathological progression of Alzheimer's disease (AD). We here investigated how extracellular Aβ peptides are internalised and focused on three different pathways: (i) via endocytic mechanisms, (ii) via the receptor for advanced glycation end products (RAGE) and (iii) via the pore-forming protein perforin. Both Aβ 40 and Aβ 42 were internalised in retinoic acid differentiated neuroblastoma (RA-SH-SY5Y) cells. A higher concentration was required for Aβ 40 (250 nM) compared with Aβ 42 (100 nM). The internalised Aβ 40 showed a dot-like pattern of distribution whereas Aβ 42 accumulated in larger and distinct formations. By confocal microscopy, we showed that Aβ 40 and Aβ 42 co-localised with mitochondria, endoplasmic reticulum (ER) and lysosomes. Aβ treatment of human primary cortical neurons (hPCN) confirmed our findings in RA-SH-SY5Y cells, but hPCN were less sensitive to Aβ; therefore, a 20 (Aβ 40 ) and 50 (Aβ 42 ) times higher concentration was needed for inducing uptake. The blocking of endocytosis completely inhibited the internalisation of Aβ peptides in RA-SH-SY5Y cells and hPCN, indicating that this is a major pathway by which Aβ enters the cells. In addition, the internalisation of Aβ 42 , but not Aβ 40 , was reduced by 55 % by blocking RAGE. Finally, for the first time we showed that pore formation in cell membranes by perforin led to Aβ internalisation in hPCN. Understanding how Aβ is internalised sheds light on the pathological role of Aβ and provides further ideas of inhibitory strategies for preventing Aβ internalisation and the spreading of neurodegeneration in AD.

  6. Serum amyloid beta peptides in patients with dementia and age-matched non-demented controls as detected by surface-enhanced laser desorption ionisation-time of flight mass spectrometry (SELDI-TOF MS).

    Science.gov (United States)

    Frankfort, Suzanne V; van Campen, Jos P C M; Tulner, Linda R; Beijnen, Jos H

    2008-09-01

    By using surface enhanced laser desorption/ionisation- time of flight mass spectrometry (SELDI-TOF MS) an amyloid beta (Abeta) profile was shown in cerebrospinal fluid (CSF) of patients with dementia. To investigate the Abeta-profile in serum with SELDI-TOF MS, to evaluate if this profile resembles CSF profiles and to investigate the correlation between intensity of Abeta-peptide-peaks in serum and clinical, demographical and genetic variables. Duplicate profiling of Abeta by an SELDI-TOF MS immunocapture assay was performed in 106 patients, suffering from Alzheimer's Disease or Vascular Dementia and age-matched non-demented control patients. Linear regression analyses were performed to investigate the intensities of four selected Abeta peaks as dependent variables in relation to the independent clinical, demographic or genetic variables. Abeta37, Abeta38 and Abeta40 were found among additional unidentified Abeta peptides, with the most pronounced Abeta peak at a molecular mass of 7752. This profile partly resembled the CSF profile. The clinical diagnosis was not a predictive independent variable, however ABCB1 genotypes C1236T, G2677T/A, age and creatinine level showed to be related to Abeta peak intensities in multivariate analyses. We found an Abeta profile in serum that partly resembled the CSF profile in demented patients. Age, creatinine levels, presence of the APOE epsilon4 allele and ABCB1 genotypes (C1236T and G2677T/A) were correlated with the Abeta serum profile. The role of P-gp as an Abeta transporter and the role of ABCB1 genotypes deserves further research. The investigated serum Abeta profile is probably not useful in the diagnosis of dementia.

  7. 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.

  8. The role of beta amyloid in Alzheimer's disease: still a cause of everything or the only one who got caught?

    Science.gov (United States)

    Verdile, Giuseppe; Fuller, Stephanie; Atwood, Craig S; Laws, Simon M; Gandy, Samuel E; Martins, Ralph N

    2004-10-01

    The beta amyloid (A beta) protein is a key molecule in the pathogenesis of Alzheimer's disease (AD). The tendency of the A beta peptide to aggregate, its reported neurotoxicity, and genetic linkage studies, have led to a hypothesis of AD pathogenesis that many AD researchers term the amyloid cascade hypothesis. In this hypothesis, an increased production of A beta results in neurodegeneration and ultimately dementia through a cascade of events. In the past 15 years, debate amongst AD researchers has arisen as to whether A beta is a cause or an effect of the pathogenic process. Recent in vitro and in vivo research has consolidated the theory that A beta is the primary cause, initiating secondary events, culminating in the neuropathological hallmarks associated with AD. This research has led to the development of therapeutic agents, currently in human clinical trials, which target A beta.

  9. AmyloidPeptide Induces Prion Protein Amyloid Formation: Evidence for Its Widespread Amyloidogenic Effect.

    Science.gov (United States)

    Honda, Ryo

    2018-04-12

    Transmissible spongiform encephalopathy is associated with misfolding of prion protein (PrP) into an amyloid β-rich aggregate. Previous studies have indicated that PrP interacts with Alzheimer's disease amyloidpeptide (Aβ), but it remains elusive how this interaction impacts on the misfolding of PrP. This study presents the first in vitro evidence that Aβ induces PrP-amyloid formation at submicromolar concentrations. Interestingly, systematic mutagenesis of PrP revealed that Aβ requires no specific amino acid sequences in PrP, and induces the misfolding of other unrelated proteins (insulin and lysozyme) into amyloid fibrils in a manner analogous to PrP. This unanticipated nonspecific amyloidogenic effect of Aβ indicates that this peptide might be involved in widespread protein aggregation, regardless of the amino acid sequences of target proteins, and exacerbate the pathology of many neurodegenerative diseases. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Stabilization of a β-hairpin in monomeric Alzheimer's amyloidpeptide inhibits amyloid formation

    OpenAIRE

    Hoyer, Wolfgang; Grönwall, Caroline; Jonsson, Andreas; Ståhl, Stefan; Härd, Torleif

    2008-01-01

    According to the amyloid hypothesis, the pathogenesis of Alzheimer's disease is triggered by the oligomerization and aggregation of the amyloid-β (Aβ) peptide into protein plaques. Formation of the potentially toxic oligomeric and fibrillar Aβ assemblies is accompanied by a conformational change toward a high content of β-structure. Here, we report the solution structure of Aβ(1–40) in complex with the phage-display selected affibody protein ZAβ3, a binding protein of nanomolar affinity. Boun...

  11. Effect of four medicinal plants on amyloid-beta induced neurotoxicity in SH-SY5Y Cells

    CSIR Research Space (South Africa)

    Adewusi, EA

    2013-01-01

    Full Text Available Amyloid-beta peptide (Aß) is implicated in the pathogenesis of Alzheimer’s disease (AD), a neurodegenerative disorder. This study was designed to determine the effect of four medicinal plants used to treat neurodegenerative diseases on Aß...

  12. Beta-amyloid, cholinergní neurony a Alzheimerova choroba

    Czech Academy of Sciences Publication Activity Database

    Kašparová, Jana; Doležal, Vladimír

    2002-01-01

    Roč. 51, č. 2 (2002), s. 82-94 ISSN 0009-0557 R&D Projects: GA MZd NF5183; GA ČR GA305/01/0283 Institutional research plan: CEZ:AV0Z5011922 Keywords : Alzheimer 's disease * beta-amyloid * cholinergic neurons Subject RIV: FR - Pharmacology ; Medidal Chemistry

  13. Quantification of amyloid-beta 40 in cerebrospinal fluid

    NARCIS (Netherlands)

    Verwey, N.A.; Veerhuis, R.; Twaalfhoven, H.A.M.; Wouters, D.; Hoozemans, J.J.M.; Bollen, Y.J.M.; Killestein, J.; Bibl, M.; Wiltfang, J.; Hack, C.E.; Scheltens, P.; Blankenstein, M.A.

    2009-01-01

    Background: Truncated forms and full-length forms of the amyloid-beta 40 (Aβ40) are key molecules in the pathogenesis of dementia, and are detectable in CSF. Reliable methods to detect these biomarkers in CSF are of great importance for understanding the disease mechanisms and for diagnostic

  14. AFM-based force spectroscopy measurements of mature amyloid fibrils of the peptide glucagon

    DEFF Research Database (Denmark)

    Dong, M. D.; Hovgaard, M. B.; Mamdouh, W.

    2008-01-01

    We report on the mechanical characterization of individual mature amyloid fibrils by atomic force microscopy (AFM) and AFM-based single-molecule force spectroscopy (SMFS). These self-assembling materials, formed from the 29-residue amphiphatic peptide hormone glucagon, were found to display...... a reversible elastic behaviour. Based on AFM morphology and SMFS studies, we suggest that the observed elasticity is due to a force-induced conformational transition which is reversible due to the beta-helical conformation of protofibrils, allowing a high degree of extension. The elastic properties...... of such mature fibrils contribute to their high stability, suggesting that the internal hydrophobic interactions of amyloid fibrils are likely to be of fundamental importance in the assembly of amyloid fibrils and therefore for the understanding of the progression of their associated pathogenic disorders...

  15. Detection of Alzheimer's amyloid beta aggregation by capturing molecular trails of individual assemblies

    International Nuclear Information System (INIS)

    Vestergaard, Mun'delanji; Hamada, Tsutomu; Saito, Masato; Yajima, Yoshifumi; Kudou, Monotori; Tamiya, Eiichi; Takagi, Masahiro

    2008-01-01

    Assembly of Amyloid beta (Aβ) peptides, in particular Aβ-42 is central to the formation of the amyloid plaques associated with neuro-pathologies such as Alzheimer's disease (AD). Molecular assembly of individual Aβ-42 species was observed using a simple fluorescence microscope. From the molecular movements (aka Brownian motion) of the individual peptide assemblies, we calculated a temporal evolution of the hydrodynamic radius (R H ) of the peptide at physiological temperature and pH. The results clearly show a direct relationship between R H of Aβ-42 and incubation period, corresponding to the previously reported peptide's aggregation kinetics. The data correlates highly with in solution-based label-free electrochemical detection of the peptide's aggregation, and Aβ-42 deposited on a solid surface and analysed using atomic force microscopy (AFM). To the best of our knowledge, this is the first analysis and characterisation of Aβ aggregation based on capturing molecular trails of individual assemblies. The technique enables both real-time observation and a semi-quantitative distribution profile of the various stages of Aβ assembly, at microM peptide concentration. Our method is a promising candidate for real-time observation and analysis of the effect of other pathologically-relevant molecules such as metal ions on pathways to Aβ oligomerisation and aggregation. The method is also a promising screening tool for AD therapeutics that target Aβ assembly.

  16. Arf6 controls beta-amyloid production by regulating macropinocytosis of the Amyloid Precursor Protein to lysosomes.

    Science.gov (United States)

    Tang, Weihao; Tam, Joshua H K; Seah, Claudia; Chiu, Justin; Tyrer, Andrea; Cregan, Sean P; Meakin, Susan O; Pasternak, Stephen H

    2015-07-14

    Alzheimer's disease (AD) is characterized by the deposition of Beta-Amyloid (Aβ) peptides in the brain. Aβ peptides are generated by cleavage of the Amyloid Precursor Protein (APP) by the β - and γ - secretase enzymes. Although this process is tightly linked to the internalization of cell surface APP, the compartments responsible are not well defined. We have found that APP can be rapidly internalized from the cell surface to lysosomes, bypassing early and late endosomes. Here we show by confocal microscopy and electron microscopy that this pathway is mediated by macropinocytosis. APP internalization is enhanced by antibody binding/crosslinking of APP suggesting that APP may function as a receptor. Furthermore, a dominant negative mutant of Arf6 blocks direct transport of APP to lysosomes, but does not affect classical endocytosis to endosomes. Arf6 expression increases through the hippocampus with the development of Alzheimer's disease, being expressed mostly in the CA1 and CA2 regions in normal individuals but spreading through the CA3 and CA4 regions in individuals with pathologically diagnosed AD. Disruption of lysosomal transport of APP reduces both Aβ40 and Aβ42 production by more than 30 %. Our findings suggest that the lysosome is an important site for Aβ production and that altering APP trafficking represents a viable strategy to reduce Aβ production.

  17. Exploring the early steps of aggregation of amyloid-forming peptide KFFE

    Energy Technology Data Exchange (ETDEWEB)

    Wei Guanghong [Departement de Physique and Regroupement Quebecois sur les Materiaux de Pointe, Universite de Montreal, CP 6128, succursale centre-ville, Montreal, QC, H3C 3J7 (Canada); Mousseau, Normand [Departement de Physique and Regroupement Quebecois sur les Materiaux de Pointe, Universite de Montreal, CP 6128, succursale centre-ville, Montreal, QC, H3C 3J7 (Canada); Derreumaux, Philippe [Laboratoire de Biochimie, Theorique, UPR 9080 CNRS, IBPC, Universite Paris 7 Denis-Diderot, 13 rue Pierre et Marie Curie, 75005 Paris (France)

    2004-11-10

    It has been shown recently that even a tetrapeptide can form amyloid fibrils sharing all the characteristics of amyloid fibrils built from large proteins. Recent experimental studies also suggest that the toxicity observed in several neurodegenerative diseases, such as Alzheimer's disease and Creutzfeldt-Jakob disease, is not only related to the mature fibrils themselves, but also to the soluble oligomers formed early in the process of fibrillogenesis. This raises the interest in studying the early steps of the aggregation process. Although fibril formation follows the nucleation-condensation process, characterized by the presence of lag phase, the exact pathways remain to be determined. In this study, we used the activation-relaxation technique and a generic energy model to explore the process of self-assembly and the structures of the resulting aggregates of eight KFFE peptides. Our simulations show, starting from different states with a preformed antiparallel dimer, that eight chains can self-assemble to adopt, with various orientations, four possible distant oligomeric well-aligned structures of similar energy. Two of these structures show a double-layer {beta}-sheet organization, in agreement with the structure of amyloid fibrils as observed by x-ray diffraction; another two are mixtures of dimers and trimers. Our results also suggest that octamers are likely to be below the critical size for nucleation of amyloid fibrils for small peptides.

  18. Gold Nanoparticles and Microwave Irradiation Inhibit Beta-Amyloid Amyloidogenesis

    Directory of Open Access Journals (Sweden)

    Bastus Neus

    2008-01-01

    Full Text Available Abstract Peptide-Gold nanoparticles selectively attached to β-amyloid protein (Aβ amyloidogenic aggregates were irradiated with microwave. This treatment produces dramatic effects on the Aβ aggregates, inhibiting both the amyloidogenesis and the restoration of the amyloidogenic potential. This novel approach offers a new strategy to inhibit, locally and remotely, the amyloidogenic process, which could have application in Alzheimer’s disease therapy. We have studied the irradiation effect on the amyloidogenic process in the presence of conjugates peptide-nanoparticle by transmission electronic microscopy observations and by Thioflavine T assays to quantify the amount of fibrils in suspension. The amyloidogenic aggregates rather than the amyloid fibrils seem to be better targets for the treatment of the disease. Our results could contribute to the development of a new therapeutic strategy to inhibit the amyloidogenic process in Alzheimer’s disease.

  19. Human amyloid beta protein gene locus: HaeIII RFLP

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, J E; Gonzalez-DeWhitt, P A; Fuller, F; Cordell, B; Frossard, P M [California Biotechnology Inc., Mountain View (USA); Tinklenberg, J R; Davies, H D; Eng, L F; Yesavage, J A [Stanford Univ. School of Medicine, Palo Alto, CA (USA)

    1988-07-25

    A 2.2 kb EcoRI-EcoRI fragment from the 5{prime} end of the human amyloid beta protein cDNA was isolated from a human fibroblast cDNA library and subcloned into pGEM3. HaeIII (GGCC) detects 6 invariant bands at 0.5 kb, 1.0 kb, 1.1 kb, 1.3 kb, 1.4 kb and 1.6 kb and a two-allele polymorphism with bands at either 1.9 kb or 2.1 kb. Its frequency was studied in 50 North Americans. Human amyloid beta protein gene mapped to the long arm of chromosome 21 (21q11.2-21q21) by Southern blot analysis of human-rodent somatic cell hybrids. Co-dominant segregation was observed in two families (15 individuals).

  20. Cross-interactions between the Alzheimer Disease AmyloidPeptide and Other Amyloid Proteins: A Further Aspect of the Amyloid Cascade Hypothesis.

    Science.gov (United States)

    Luo, Jinghui; Wärmländer, Sebastian K T S; Gräslund, Astrid; Abrahams, Jan Pieter

    2016-08-05

    Many protein folding diseases are intimately associated with accumulation of amyloid aggregates. The amyloid materials formed by different proteins/peptides share many structural similarities, despite sometimes large amino acid sequence differences. Some amyloid diseases constitute risk factors for others, and the progression of one amyloid disease may affect the progression of another. These connections are arguably related to amyloid aggregates of one protein being able to directly nucleate amyloid formation of another, different protein: the amyloid cross-interaction. Here, we discuss such cross-interactions between the Alzheimer disease amyloid-β (Aβ) peptide and other amyloid proteins in the context of what is known from in vitro and in vivo experiments, and of what might be learned from clinical studies. The aim is to clarify potential molecular associations between different amyloid diseases. We argue that the amyloid cascade hypothesis in Alzheimer disease should be expanded to include cross-interactions between Aβ and other amyloid proteins. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. Rationally designed turn promoting mutation in the amyloidpeptide sequence stabilizes oligomers in solution.

    Directory of Open Access Journals (Sweden)

    Jayakumar Rajadas

    Full Text Available Enhanced production of a 42-residue beta amyloid peptide (Aβ(42 in affected parts of the brain has been suggested to be the main causative factor for the development of Alzheimer's Disease (AD. The severity of the disease depends not only on the amount of the peptide but also its conformational transition leading to the formation of oligomeric amyloid-derived diffusible ligands (ADDLs in the brain of AD patients. Despite being significant to the understanding of AD mechanism, no atomic-resolution structures are available for these species due to the evanescent nature of ADDLs that hinders most structural biophysical investigations. Based on our molecular modeling and computational studies, we have designed Met35Nle and G37p mutations in the Aβ(42 peptide (Aβ(42Nle35p37 that appear to organize Aβ(42 into stable oligomers. 2D NMR on the Aβ(42Nle35p37 peptide revealed the occurrence of two β-turns in the V24-N27 and V36-V39 stretches that could be the possible cause for the oligomer stability. We did not observe corresponding NOEs for the V24-N27 turn in the Aβ(21-43Nle35p37 fragment suggesting the need for the longer length amyloid peptide to form the stable oligomer promoting conformation. Because of the presence of two turns in the mutant peptide which were absent in solid state NMR structures for the fibrils, we propose, fibril formation might be hindered. The biophysical information obtained in this work could aid in the development of structural models for toxic oligomer formation that could facilitate the development of therapeutic approaches to AD.

  2. Alzheimer's disease amyloid-beta links lens and brain pathology in Down syndrome.

    Directory of Open Access Journals (Sweden)

    Juliet A Moncaster

    2010-05-01

    Full Text Available Down syndrome (DS, trisomy 21 is the most common chromosomal disorder and the leading genetic cause of intellectual disability in humans. In DS, triplication of chromosome 21 invariably includes the APP gene (21q21 encoding the Alzheimer's disease (AD amyloid precursor protein (APP. Triplication of the APP gene accelerates APP expression leading to cerebral accumulation of APP-derived amyloid-beta peptides (Abeta, early-onset AD neuropathology, and age-dependent cognitive sequelae. The DS phenotype complex also includes distinctive early-onset cerulean cataracts of unknown etiology. Previously, we reported increased Abeta accumulation, co-localizing amyloid pathology, and disease-linked supranuclear cataracts in the ocular lenses of subjects with AD. Here, we investigate the hypothesis that related AD-linked Abeta pathology underlies the distinctive lens phenotype associated with DS. Ophthalmological examinations of DS subjects were correlated with phenotypic, histochemical, and biochemical analyses of lenses obtained from DS, AD, and normal control subjects. Evaluation of DS lenses revealed a characteristic pattern of supranuclear opacification accompanied by accelerated supranuclear Abeta accumulation, co-localizing amyloid pathology, and fiber cell cytoplasmic Abeta aggregates (approximately 5 to 50 nm identical to the lens pathology identified in AD. Peptide sequencing, immunoblot analysis, and ELISA confirmed the identity and increased accumulation of Abeta in DS lenses. Incubation of synthetic Abeta with human lens protein promoted protein aggregation, amyloid formation, and light scattering that recapitulated the molecular pathology and clinical features observed in DS lenses. These results establish the genetic etiology of the distinctive lens phenotype in DS and identify the molecular origin and pathogenic mechanism by which lens pathology is expressed in this common chromosomal disorder. Moreover, these findings confirm increased Abeta

  3. Development and characterization of a TAPIR-like mouse monoclonal antibody to amyloid-beta.

    Science.gov (United States)

    Wang, Jun; Hara, Hideo; Makifuchi, Takao; Tabira, Takeshi

    2008-06-01

    Tissue amyloid plaque immuno-reactive (TAPIR) antibody was better related to the effect of immunotherapy in Alzheimer's disease (AD) than ELISA antibody. Here we used a hybridoma technique to develop a TAPIR-like anti-human amyloid-beta (Abeta) mouse monoclonal antibody. The obtained monoclonal antibody, 3.4A10, was an IgG2b isotype and recognized N-terminal portion of Abeta1-42 without binding denatured or native amyloid-beta protein precursor. It had higher affinity to Abeta1-42 than to Abeta1-40 by Biacore affinity analysis and stained preferably the peripheral part of senile plaques and recognized the plaque core less than 4G8. It inhibited the Abeta1-42 fibril formation as well as degraded pre-aggregated Abeta1-42 peptide in a thioflavin T fluorescence spectrophotometry assay. The in vivo studies showed that 3.4A10 treatment decreased amyloid burden compared to the control group and significantly reduced Abeta42 levels rather than Abeta40 levels in brain lysates as well as the Abeta*56 oligomer (12mer) in TBS fraction of the brain lysates. 3.4A10 entered brain and decorated some plaques, which is surrounded by more Iba1-positive microglia. 3.4A10 therapy did not induce lymphocytic infiltration and obvious increase in microhemorrhage. We conclude that 3.4A10 is a TAPIR-like anti-human amyloid monoclonal antibody, and has a potential of therapeutic application for AD.

  4. Analysis of a compartmental model of amyloid beta production, irreversible loss and exchange in humans.

    Science.gov (United States)

    Elbert, Donald L; Patterson, Bruce W; Bateman, Randall J

    2015-03-01

    Amyloid beta (Aβ) peptides, and in particular Aβ42, are found in senile plaques associated with Alzheimer's disease. A compartmental model of Aβ production, exchange and irreversible loss was recently developed to explain the kinetics of isotope-labeling of Aβ peptides collected in cerebrospinal fluid (CSF) following infusion of stable isotope-labeled leucine in humans. The compartmental model allowed calculation of the rates of production, irreversible loss (or turnover) and short-term exchange of Aβ peptides. Exchange of Aβ42 was particularly pronounced in amyloid plaque-bearing participants. In the current work, we describe in much greater detail the characteristics of the compartmental model to two distinct audiences: physician-scientists and biokineticists. For physician-scientists, we describe through examples the types of questions the model can and cannot answer, as well as correct some misunderstandings of previous kinetic analyses applied to this type of isotope labeling data. For biokineticists, we perform a system identifiability analysis and a sensitivity analysis of the kinetic model to explore the global and local properties of the model. Combined, these analyses motivate simplifications from a more comprehensive physiological model to the final model that was previously presented. The analyses clearly demonstrate that the current dataset and compartmental model allow determination with confidence a single 'turnover' parameter, a single 'exchange' parameter and a single 'delay' parameter. When combined with CSF concentration data for the Aβ peptides, production rates may also be obtained. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. A comparative analysis of the aggregation behavior of amyloidpeptide variants

    NARCIS (Netherlands)

    Vandersteen, Annelies; Hubin, Ellen; Sarroukh, Rabia; De Baets, Greet; Schymkowitz, Joost; Rousseau, Frederic; Subramaniam, Vinod; Raussens, Vincent; Wenschuh, Holger; Wildemann, Dirk; Broersen, Kerensa

    2012-01-01

    Aggregated forms of the amyloidpeptide are hypothesized to act as the prime toxic agents in Alzheimer disease (AD). The in vivo amyloidpeptide pool consists of both C- and N-terminally truncated or mutated peptides, and the composition thereof significantly determines AD risk. Other

  6. The role of mutated amyloid beta 1-42 stimulating dendritic cells in a PDAPP transgenic mouse

    Directory of Open Access Journals (Sweden)

    LI Jia-lin

    2012-06-01

    Full Text Available Background Amyloid plaque is one of the pathological hallmarks of Alzheimer's disease (AD. Anti-beta-amyloid (Aβ immunotherapy is effective in removing brain Aβ, but has shown to be associated with detrimental effects. To avoid severe adverse effects such as meningoencephalitis induced by amyloid beta vaccine with adjuvant, and take advantage of amyloid beta antibody's therapeutic effect on Alzheimer's disease sufficiently, our group has developed a new Alzheimer vaccine with mutated amyloid beta 1-42 peptide stimulating dendritic cells (DC. Our previous work has confirmed that DC vaccine can induce adequate anti-amyloid beta antibody in PDAPP Tg mice safely and efficiently. The DC vaccine can improve impaired learning and memory in the Alzheimer's animal model, and did not cause microvasculitis, microhemorrhage or meningoencephalitis in the animal model. However, the exact mechanism of immunotherapy which reduces Aβ deposition remains unknown. In this report, we studied the mechanism of the vaccine, thinking that this may have implications for better understanding of the pathogenesis of Alzheimer's disease. Methods A new Alzheimer vaccine with mutated amyloid beta 1-42 peptide stimulating DC which were obtained from C57/B6 mouse bone marrow was developed. Amyloid beta with Freund's adjuvant was inoculated at the same time to act as positive control. After the treatment was done, the samples of brains were collected, fixed, cut. Immunohistochemical staining was performed to observe the expression of the nuclear hormone liver X receptor (LXR, membrane-bound protein tyrosine phosphatase (CD45, the ATP-binding cassette family of active transporters (ABCA1, receptor for advanced glycation end products (RAGE, β-site APP-cleaving enzyme (BACE and Aβ in mouse brain tissue. Semi-quantitative analysis was used to defect CA1, CA2, CA3, DG, Rad in hippocampus region and positive neuron in cortex region. Results Aβ was significantly reduced in the

  7. Lowering beta-amyloid levels rescues learning and memory in a Down syndrome mouse model.

    Directory of Open Access Journals (Sweden)

    William J Netzer

    Full Text Available beta-amyloid levels are elevated in Down syndrome (DS patients throughout life and are believed to cause Alzheimer's disease (AD in adult members of this population. However, it is not known if beta-amyloid contributes to intellectual disability in younger individuals. We used a gamma-secretase inhibitor to lower beta-amyloid levels in young mice that model DS. This treatment corrected learning deficits characteristic of these mice, suggesting that beta-amyloid-lowering therapies might improve cognitive function in young DS patients.

  8. Plasma Membrane Protein Profiling in Beta-Amyloid-Treated Microglia Cell Line.

    Science.gov (United States)

    Correani, Virginia; Di Francesco, Laura; Mignogna, Giuseppina; Fabrizi, Cinzia; Leone, Stefano; Giorgi, Alessandra; Passeri, Alessia; Casata, Roberto; Fumagalli, Lorenzo; Maras, Bruno; Schininà, M Eugenia

    2017-09-01

    In the responsiveness of microglia to toxic stimuli, plasma membrane proteins play a key role. In this study we treated with a synthetic beta amyloid peptide murine microglial cells metabolically differently labelled with stable isotope amino acids (SILAC). The plasma membrane was selectively enriched by a multi-stage aqueous two-phase partition system. We were able to identify by 1D-LC-MS/MS analyses 1577 proteins, most of them are plasma membrane proteins according to the Gene Ontology annotation. An unchanged level of amyloid receptors in this data set suggests that microglia preserve their responsiveness capability to the environment even after 24-h challenge with amyloid peptides. On the other hand, 14 proteins were observed to change their plasma membrane abundance to a statistically significant extent. Among these, we proposed as reliable biomarkers of the inflammatory microglia phenotype in AD damaged tissues MAP/microtubule affinity-regulating kinase 3 (MARK3), Interferon-induced transmembrane protein 3 (IFITM3), Annexins A5 and A7 (ANXA5, ANXA7) and Neuropilin-1 (NRP1), all proteins known to be involved in the inflammation processes and in microtubule network assembly rate. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Neuroinflammation and Complexes of 17 beta-Hydroxysteroid Dehydrogenase type 10-Amyloid beta in Alzheimer's Disease

    Czech Academy of Sciences Publication Activity Database

    Krištofíková, Z.; Řípová, D.; Bartoš, A.; Bocková, Markéta; Hegnerová, Kateřina; Říčný, J.; Čechová, L.; Vrajová, M.; Homola, Jiří

    2013-01-01

    Roč. 10, č. 2 (2013), s. 165-173 ISSN 1567-2050 R&D Projects: GA MZd(CZ) NT11225 Institutional support: RVO:67985882 Keywords : Amyloid beta * mitochondrial enzyme * Alzheimer 's disease Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 3.796, year: 2013

  10. Successful adjuvant-free vaccination of BALB/c mice with mutated amyloid β peptides

    Directory of Open Access Journals (Sweden)

    Wahi Monika M

    2008-02-01

    Full Text Available Abstract Background A recent human clinical trial of an Alzheimer's disease (AD vaccine using amyloid beta (Aβ 1–42 plus QS-21 adjuvant produced some positive results, but was halted due to meningoencephalitis in some participants. The development of a vaccine with mutant Aβ peptides that avoids the use of an adjuvant may result in an effective and safer human vaccine. Results All peptides tested showed high antibody responses, were long-lasting, and demonstrated good memory response. Epitope mapping indicated that peptide mutation did not lead to epitope switching. Mutant peptides induced different inflammation responses as evidenced by cytokine profiles. Ig isotyping indicated that adjuvant-free vaccination with peptides drove an adequate Th2 response. All anti-sera from vaccinated mice cross-reacted with human Aβ in APP/PS1 transgenic mouse brain tissue. Conclusion Our study demonstrated that an adjuvant-free vaccine with different Aβ peptides can be an effective and safe vaccination approach against AD. This study represents the first report of adjuvant-free vaccines utilizing Aβ peptides carrying diverse mutations in the T-cell epitope. These largely positive results provide encouragement for the future of the development of human vaccinations for AD.

  11. Lipopolysaccharide induces amyloid formation of antimicrobial peptide HAL-2.

    Science.gov (United States)

    Wang, Jiarong; Li, Yan; Wang, Xiaoming; Chen, Wei; Sun, Hongbin; Wang, Junfeng

    2014-11-01

    Lipopolysaccharide (LPS), the important component of the outer membrane of Gram-negative bacteria, contributes to the integrity of the outer membrane and protects the cell against bactericidal agents, including antimicrobial peptides. However, the mechanisms of interaction between antimicrobial peptides and LPS are not clearly understood. Halictines-2 (HAL-2), one of the novel antimicrobial peptides, was isolated from the venom of the eusocial bee Halictus sexcinctus. HAL-2 has exhibited potent antimicrobial activity against Gram-positive and Gram-negative bacteria and even against cancer cells. Here, we studied the interactions between HAL-2 and LPS to elucidate the antibacterial mechanism of HAL-2 in vitro. Our results show that HAL-2 adopts a significant degree of β-strand structure in the presence of LPS. LPS is capable of inducing HAL-2 amyloid formation, which may play a vital role in its antimicrobial activity. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Liquid Crystal Enabled Early Stage Detection of Beta Amyloid Formation on Lipid Monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Sadati, Monirosadat [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Apik, Aslin Izmitli [Chemical and Biological Engineering, University of Wisconsin, Madison WI 53706 USA; Armas-Perez, Julio C. [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Martinez-Gonzalez, Jose [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Hernandez-Ortiz, Juan P. [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Departamento de Materiales y Minerales, Facultad de Minas, Universidad Nacional de Colombia, Sede Medellín, Calle 75 # 79A-51, Bloque M17 Medellín Colombia; Abbott, Nicholas L. [Chemical and Biological Engineering, University of Wisconsin, Madison WI 53706 USA; de Pablo, Juan J. [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Argonne National Laboratory, Argonne IL 60439 USA

    2015-09-09

    Liquid crystals (LCs) can serve as sensitive reporters of interfacial events, and this property has been used for sensing of synthetic or biological toxins. Here it is demonstrated that LCs can distinguish distinct molecular motifs and exhibit a specific response to beta-sheet structures. That property is used to detect the formation of highly toxic protofibrils involved in neurodegenerative diseases, where it is crucial to develop methods that probe the early-stage aggregation of amyloidogenic peptides in the vicinity of biological membranes. In the proposed method, the amyloid fibrils formed at the lipid-decorated LC interface can change the orientation of LCs and form elongated and branched structures that are amplified by the mesogenic medium; however, nonamyloidogenic peptides form ellipsoidal domains of tilted LCs. Moreover, a theoretical and computational analysis is used to reveal the underlying structure of the LC, thereby providing a detailed molecular-level view of the interactions and mechanisms responsible for such motifs. The corresponding signatures can be detected at nanomolar concentrations of peptide by polarized light microscopy and much earlier than the ones that can be identified by fluorescence-based techniques. As such, it offers the potential for early diagnoses of neurodegenerative diseases and for facile testing of inhibitors of amyloid formation.

  13. Microglia kill amyloid-beta1-42 damaged neurons by a CD14-dependent process

    NARCIS (Netherlands)

    Bate, Clive; Veerhuis, Robert; Eikelenboom, Piet; Williams, Alun

    2004-01-01

    Activated microglia are closely associated with neuronal damage in Alzheimer's disease. In the present study, neurons exposed to low concentrations of amyloid-beta1-42, a toxic fragment of the amyloid-beta protein, were killed by microglia in a process that required cell-cell contact. Pre-treating

  14. Electrochemical sensing of 2D condensation in amyloid peptides

    Czech Academy of Sciences Publication Activity Database

    Kurzatkowska, K.; Ostatná, Veronika; Hamley, I.W.; Doneux, T.; Paleček, Emil

    2013-01-01

    Roč. 106, SEP2013 (2013), s. 43-48 ISSN 0013-4686 R&D Projects: GA ČR(CZ) GAP301/11/2055 Institutional support: RVO:68081707 Keywords : QUARTZ-CRYSTAL-MICROBALANCE * SELF -ASSEMBLED MONOLAYERS * BETA-SHEET PEPTIDES Subject RIV: BO - Biophysics Impact factor: 4.086, year: 2013

  15. A hydrogel biosensor for high selective and sensitive detection of amyloid-beta oligomers

    Directory of Open Access Journals (Sweden)

    Sun LP

    2018-02-01

    Full Text Available Liping Sun,1 Yong Zhong,1 Jie Gui,1 Xianwu Wang,1 Xiaorong Zhuang,2 Jian Weng1 1Key Laboratory of Biomedical Engineering of Fujian Province, Research Center of Biomedical Engineering of Xiamen, Department of Biomaterials, College of Materials, Xiamen University, 2Department of Neurology, The Affiliated Zhongshan Hospital of Xiamen University, Xiamen, People’s Republic of China Background: Alzheimer’s disease (AD is a neurodegenerative disorder characterized by progressive cognitive and memory impairment. It is the most common neurological disease that causes dementia. Soluble amyloid-beta oligomers (AβO in blood or cerebrospinal fluid (CSF are the pathogenic biomarker correlated with AD. Methods: A simple electrochemical biosensor using graphene oxide/gold nanoparticles (GNPs hydrogel electrode was developed in this study. Thiolated cellular prion protein (PrPC peptide probe was immobilized on GNPs of the hydrogel electrode to construct an AβO biosensor. Electrochemical impedance spectroscopy was utilized for AβO analysis. Results: The specific binding between AβO and PrPC probes on the hydrogel electrode resulted in an increase in the electron-transfer resistance. The biosensor showed high specificity and sensitivity for AβO detection. It could selectively differentiate AβO from amyloid-beta (Aβ monomers or fibrils. Meanwhile, it was highly sensitive to detect as low as 0.1 pM AβO in artificial CSF or blood plasma. The linear range for AβO detection is from 0.1 pM to 10 nM. Conclusion: This biosensor could be used as a cost-effective tool for early diagnosis of AD due to its high electrochemical performance and bionic structure. Keywords: Alzheimer’s disease, amyloid-beta oligomer, graphene, gold nanoparticles, biosensor

  16. Two distinct β-sheet structures in Italian-mutant amyloid-beta fibrils : a potential link to different clinical phenotypes

    NARCIS (Netherlands)

    Hubin, Ellen; Deroo, Stéphanie; Schierle, Gabriele Kaminksi; Kaminski, Clemens; Serpell, Louise; Subramaniam, Vinod; van Nuland, Nico; Broersen, Kerensa; Raussens, Vincent; Sarroukh, Rabia

    2015-01-01

    Most Alzheimer's disease (AD) cases are late-onset and characterized by the aggregation and deposition of the amyloid-beta (Aβ) peptide in extracellular plaques in the brain. However, a few rare and hereditary Aβ mutations, such as the Italian Glu22-to-Lys (E22K) mutation, guarantee the development

  17. Stabilization of a β-hairpin in monomeric Alzheimer's amyloidpeptide inhibits amyloid formation

    Science.gov (United States)

    Hoyer, Wolfgang; Grönwall, Caroline; Jonsson, Andreas; Ståhl, Stefan; Härd, Torleif

    2008-01-01

    According to the amyloid hypothesis, the pathogenesis of Alzheimer's disease is triggered by the oligomerization and aggregation of the amyloid-β (Aβ) peptide into protein plaques. Formation of the potentially toxic oligomeric and fibrillar Aβ assemblies is accompanied by a conformational change toward a high content of β-structure. Here, we report the solution structure of Aβ(1–40) in complex with the phage-display selected affibody protein ZAβ3, a binding protein of nanomolar affinity. Bound Aβ(1–40) features a β-hairpin comprising residues 17–36, providing the first high-resolution structure of Aβ in β conformation. The positions of the secondary structure elements strongly resemble those observed for fibrillar Aβ. ZAβ3 stabilizes the β-sheet by extending it intermolecularly and by burying both of the mostly nonpolar faces of the Aβ hairpin within a large hydrophobic tunnel-like cavity. Consequently, ZAβ3 acts as a stoichiometric inhibitor of Aβ fibrillation. The selected Aβ conformation allows us to suggest a structural mechanism for amyloid formation based on soluble oligomeric hairpin intermediates. PMID:18375754

  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. A hydrogel biosensor for high selective and sensitive detection of amyloid-beta oligomers.

    Science.gov (United States)

    Sun, Liping; Zhong, Yong; Gui, Jie; Wang, Xianwu; Zhuang, Xiaorong; Weng, Jian

    2018-01-01

    Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive and memory impairment. It is the most common neurological disease that causes dementia. Soluble amyloid-beta oligomers (AβO) in blood or cerebrospinal fluid (CSF) are the pathogenic biomarker correlated with AD. A simple electrochemical biosensor using graphene oxide/gold nanoparticles (GNPs) hydrogel electrode was developed in this study. Thiolated cellular prion protein (PrP C ) peptide probe was immobilized on GNPs of the hydrogel electrode to construct an AβO biosensor. Electrochemical impedance spectroscopy was utilized for AβO analysis. The specific binding between AβO and PrP C probes on the hydrogel electrode resulted in an increase in the electron-transfer resistance. The biosensor showed high specificity and sensitivity for AβO detection. It could selectively differentiate AβO from amyloid-beta (Aβ) monomers or fibrils. Meanwhile, it was highly sensitive to detect as low as 0.1 pM AβO in artificial CSF or blood plasma. The linear range for AβO detection is from 0.1 pM to 10 nM. This biosensor could be used as a cost-effective tool for early diagnosis of AD due to its high electrochemical performance and bionic structure.

  20. Natural Modulators of Amyloid-Beta Precursor Protein Processing

    Science.gov (United States)

    Zhang, Can; Tanzi, Rudolph E.

    2013-01-01

    Alzheimer’s disease (AD) is a devastating neurodegenerative disease and the primary cause of dementia, with no cure currently available. The pathogenesis of AD is believed to be primarily driven by Aβ, the principal component of senile plaques. Aβ is an ~4 kDa peptide generated from the amyloid-β precursor protein (APP) through proteolytic secretases. Natural products, particularly those utilized in traditional Chinese medicine (TCM), have a long history alleviating common clinical disorders, including dementia. However, the cell/molecular pathways mediated by these natural products are largely unknown until recently when the underlying molecular mechanisms of the disorders begin to be elucidated. Here, the mechanisms with which natural products modulate the pathogenesis of AD are discussed, in particular, by focusing on their roles in the processing of APP. PMID:22998566

  1. Unwinding fibril formation of medin, the peptide of the most common form of human amyloid

    International Nuclear Information System (INIS)

    Larsson, Annika; Soederberg, Linda; Westermark, Gunilla T.; Sletten, Knut; Engstroem, Ulla; Tjernberg, Lars O.; Naeslund, Jan; Westermark, Per

    2007-01-01

    Medin amyloid affects the medial layer of the thoracic aorta of most people above 50 years of age. The consequences of this amyloid are not completely known but the deposits may contribute to diseases such as thoracic aortic aneurysm and dissection or to the general diminished elasticity of blood vessels seen in elderly people. We show that the 50-amino acid residue peptide medin forms amyloid-like fibrils in vitro. With the use of Congo red staining, Thioflavin T fluorescence, electron microscopy, and a solid-phase binding assay on different synthetic peptides, we identified the last 18-19 amino acid residues to constitute the amyloid-promoting region of medin. We also demonstrate that the two C-terminal phenylalanines, previously suggested to be of importance for amyloid formation, are not required for medin amyloid formation

  2. Minocycline does not affect amyloid beta phagocytosis by human microglial cells

    NARCIS (Netherlands)

    Familian, Atoosa; Eikelenboom, Piet; Veerhuis, Robert

    2007-01-01

    Activated microglia accumulate in amyloid beta (Abeta) plaques containing amyloid associated factors SAP and C1q in Alzheimer's disease (AD) brain. Microglia are involved in AD pathogenesis by promoting Abeta plaque formation and production of pro-inflammatory cytokines. On the other hand,

  3. How ionic strength affects the conformational behavior of human and rat beta amyloids--a computational study.

    Directory of Open Access Journals (Sweden)

    Zdeněk Kříž

    Full Text Available Progressive cerebral deposition of amyloid beta occurs in Alzheimers disease and during the aging of certain mammals (human, monkey, dog, bear, cow, cat but not others (rat, mouse. It is possibly due to different amino acid sequences at positions 5, 10 and 13. To address this issue, we performed series of 100 ns long trajectories (each trajectory was run twice with different initial velocity distribution on amyloid beta (1-42 with the human and rat amino acid sequence in three different environments: water with only counter ions, water with NaCl at a concentration of 0.15 M as a model of intracellular Na(+ concentration at steady state, and water with NaCl at a concentration of 0.30 M as a model of intracellular Na(+ concentration under stimulated conditions. We analyzed secondary structure stability, internal hydrogen bonds, and residual fluctuation. It was observed that the change in ionic strength affects the stability of internal hydrogen bonds. Increasing the ionic strength increases atomic fluctuation in the hydrophobic core of the human amyloid, and decreases the atomic fluctuation in the case of rat amyloid. The secondary structure analyses show a stable α-helix part between residues 10 and 20. However, C-terminus of investigated amyloids is much more flexible showing no stable secondary structure elements. Increasing ionic strength of the solvent leads to decreasing stability of the secondary structural elements. The difference in conformational behavior of the three amino acids at position 5, 10 and 13 for human and rat amyloids significantly changes the conformational behavior of the whole peptide.

  4. Mitochondrion-derived reactive oxygen species lead to enhanced amyloid beta formation

    NARCIS (Netherlands)

    Leuner, K.; Schutt, T.; Kurz, C.; Eckert, S.H.; Schiller, C.; Occhipinti, A.; Mai, S.; Jendrach, M.; Eckert, G.P.; Kruse, S.E.; Palmiter, R.D.; Brandt, U.; Drose, S.; Wittig, I.; Willem, M.; Haass, C.; Reichert, A.S.; Muller, W.E.

    2012-01-01

    AIMS: Intracellular amyloid beta (Abeta) oligomers and extracellular Abeta plaques are key players in the progression of sporadic Alzheimer's disease (AD). Still, the molecular signals triggering Abeta production are largely unclear. We asked whether mitochondrion-derived reactive oxygen species

  5. Interaction of the amyloid β peptide with sodium dodecyl sulfate as a membrane-mimicking detergent.

    NARCIS (Netherlands)

    Hashemi, Shabestari M.; Meeuwenoord, N.J.; Filippov, D.V.; Huber, M.I.

    2016-01-01

    The amyloid β (A β) peptide is important in the context of Alzheimer's disease, since it is one of the major components of the fibrils that constitute amyloid plaques. Agents that can influence fibril formation are important, and of those, membrane mimics are particularly relevant, because the

  6. Glycation induces formation of amyloid cross-beta structure in albumin.

    Science.gov (United States)

    Bouma, Barend; Kroon-Batenburg, Loes M J; Wu, Ya-Ping; Brünjes, Bettina; Posthuma, George; Kranenburg, Onno; de Groot, Philip G; Voest, Emile E; Gebbink, Martijn F B G

    2003-10-24

    Amyloid fibrils are components of proteinaceous plaques that are associated with conformational diseases such as Alzheimer's disease, transmissible spongiform encephalopathies, and familial amyloidosis. Amyloid polypeptides share a specific quarternary structure element known as cross-beta structure. Commonly, fibrillar aggregates are modified by advanced glycation end products (AGE). In addition, AGE formation itself induces protein aggregation. Both amyloid proteins and protein-AGE adducts bind multiligand receptors, such as receptor for AGE, CD36, and scavenger receptors A and B type I, and the serine protease tissue-type plasminogen activator (tPA). Based on these observations, we hypothesized that glycation induces refolding of globular proteins, accompanied by formation of cross-beta structure. Using transmission electron microscopy, we demonstrate here that glycated albumin condensates into fibrous or amorphous aggregates. These aggregates bind to amyloid-specific dyes Congo red and thioflavin T and to tPA. In contrast to globular albumin, glycated albumin contains amino acid residues in beta-sheet conformation, as measured with circular dichroism spectropolarimetry. Moreover, it displays cross-beta structure, as determined with x-ray fiber diffraction. We conclude that glycation induces refolding of initially globular albumin into amyloid fibrils comprising cross-beta structure. This would explain how glycated ligands and amyloid ligands can bind to the same multiligand "cross-beta structure" receptors and to tPA.

  7. Key aromatic/hydrophobic amino acids controlling a cross-amyloid peptide interaction versus amyloid self-assembly.

    Science.gov (United States)

    Bakou, Maria; Hille, Kathleen; Kracklauer, Michael; Spanopoulou, Anna; Frost, Christina V; Malideli, Eleni; Yan, Li-Mei; Caporale, Andrea; Zacharias, Martin; Kapurniotu, Aphrodite

    2017-09-01

    The interaction of the intrinsically disordered polypeptide islet amyloid polypeptide (IAPP), which is associated with type 2 diabetes (T2D), with the Alzheimer's disease amyloid-β (Aβ) peptide modulates their self-assembly into amyloid fibrils and may link the pathogeneses of these two cell-degenerative diseases. However, the molecular determinants of this interaction remain elusive. Using a systematic alanine scan approach, fluorescence spectroscopy, and other biophysical methods, including heterocomplex pulldown assays, far-UV CD spectroscopy, the thioflavin T binding assay, transmission EM, and molecular dynamics simulations, here we identified single aromatic/hydrophobic residues within the amyloid core IAPP region as hot spots or key residues of its cross-interaction with Aβ40(42) peptide. Importantly, we also find that none of these residues in isolation plays a key role in IAPP self-assembly, whereas simultaneous substitution of four aromatic/hydrophobic residues with Ala dramatically impairs both IAPP self-assembly and hetero-assembly with Aβ40(42). Furthermore, our experiments yielded several novel IAPP analogs, whose sequences are highly similar to that of IAPP but have distinct amyloid self- or cross-interaction potentials. The identified similarities and major differences controlling IAPP cross-peptide interaction with Aβ40(42) versus its amyloid self-assembly offer a molecular basis for understanding the underlying mechanisms. We propose that these insights will aid in designing intervention strategies and novel IAPP analogs for the management of type 2 diabetes, Alzheimer's disease, or other diseases related to IAPP dysfunction or cross-amyloid interactions. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. Kinetic and structural characterization of amyloidpeptide hydrolysis by human angiotensin-1-converting enzyme.

    Science.gov (United States)

    Larmuth, Kate M; Masuyer, Geoffrey; Douglas, Ross G; Schwager, Sylva L; Acharya, K Ravi; Sturrock, Edward D

    2016-03-01

    Angiotensin-1-converting enzyme (ACE), a zinc metallopeptidase, consists of two homologous catalytic domains (N and C) with different substrate specificities. Here we report kinetic parameters of five different forms of human ACE with various amyloid beta (Aβ) substrates together with high resolution crystal structures of the N-domain in complex with Aβ fragments. For the physiological Aβ(1-16) peptide, a novel ACE cleavage site was found at His14-Gln15. Furthermore, Aβ(1-16) was preferentially cleaved by the individual N-domain; however, the presence of an inactive C-domain in full-length somatic ACE (sACE) greatly reduced enzyme activity and affected apparent selectivity. Two fluorogenic substrates, Aβ(4-10)Q and Aβ(4-10)Y, underwent endoproteolytic cleavage at the Asp7-Ser8 bond with all ACE constructs showing greater catalytic efficiency for Aβ(4-10)Y. Surprisingly, in contrast to Aβ(1-16) and Aβ(4-10)Q, sACE showed positive domain cooperativity and the double C-domain (CC-sACE) construct no cooperativity towards Aβ(4-10)Y. The structures of the Aβ peptide-ACE complexes revealed a common mode of peptide binding for both domains which principally targets the C-terminal P2' position to the S2' pocket and recognizes the main chain of the P1' peptide. It is likely that N-domain selectivity for the amyloid peptide is conferred through the N-domain specific S2' residue Thr358. Additionally, the N-domain can accommodate larger substrates through movement of the N-terminal helices, as suggested by the disorder of the hinge region in the crystal structures. Our findings are important for the design of domain selective inhibitors as the differences in domain selectivity are more pronounced with the truncated domains compared to the more physiological full-length forms. The atomic coordinates and structure factors for N-domain ACE with Aβ peptides 4-10 (5AM8), 10-16 (5AM9), 1-16 (5AMA), 35-42 (5AMB) and (4-10)Y (5AMC) complexes have been deposited in the

  9. Amyloid beta precursor protein regulates male sexual behavior.

    Science.gov (United States)

    Park, Jin Ho; Bonthius, Paul J; Tsai, Houng-Wei; Bekiranov, Stefan; Rissman, Emilie F

    2010-07-28

    Sexual behavior is variable between individuals, ranging from celibacy to sexual addictions. Within normal populations of individual men, ranging from young to middle aged, testosterone levels do not correlate with libido. To study the genetic mechanisms that contribute to individual differences in male sexual behavior, we used hybrid B6D2F1 male mice, which are a cross between two common inbred strains (C57BL/6J and DBA/2J). Unlike most laboratory rodent species in which male sexual behavior is highly dependent upon gonadal steroids, sexual behavior in a large proportion of these hybrid male mice after castration is independent of gonadal steroid hormones and their receptors; thus, we have the ability to discover novel genes involved in this behavior. Gene expression arrays, validation of gene candidates, and transgenic mice that overexpress one of the genes of interest were used to reveal genes involved in maintenance of male sexual behavior. Several genes related to neuroprotection and neurodegeneration were differentially expressed in the hypothalamus of males that continued to mate after castration. Male mice overexpressing the human form of one of these candidate genes, amyloid beta precursor protein (APP), displayed enhanced sexual behavior before castration and maintained sexual activity for a longer duration after castration compared with controls. Our results reveal a novel and unexpected relationship between APP and male sexual behavior. We speculate that declining APP during normal aging in males may contribute to the loss of sexual function.

  10. Transthyretin protects against A-beta peptide toxicity by proteolytic cleavage of the peptide: a mechanism sensitive to the Kunitz protease inhibitor.

    Directory of Open Access Journals (Sweden)

    Rita Costa

    Full Text Available Alzheimer's disease (AD is a neurodegenerative disorder characterized by the deposition of amyloid beta-peptide (A-Beta in the brain. Transthyretin (TTR is a tetrameric protein of about 55 kDa mainly produced in the liver and choroid plexus of the brain. The known physiological functions of TTR are the transport of thyroid hormone T(4 and retinol, through binding to the retinol binding protein. TTR has also been established as a cryptic protease able to cleave ApoA-I in vitro. It has been described that TTR is involved in preventing A-Beta fibrilization, both by inhibiting and disrupting A-Beta fibrils, with consequent abrogation of toxicity. We further characterized the nature of the TTR/A-Beta interaction and found that TTR, both recombinant or isolated from human sera, was able to proteolytically process A-Beta, cleaving the peptide after aminoacid residues 1, 2, 3, 10, 13, 14,16, 19 and 27, as determined by mass spectrometry, and reversed phase chromatography followed by N-terminal sequencing. A-Beta peptides (1-14 and (15-42 showed lower amyloidogenic potential than the full length counterpart, as assessed by thioflavin binding assay and ultrastructural analysis by transmission electron microscopy. A-Beta cleavage by TTR was inhibited in the presence of an alphaAPP peptide containing the Kunitz Protease Inhibitor (KPI domain but not in the presence of the secreted alphaAPP derived from the APP isoform 695 without the KPI domain. TTR was also able to degrade aggregated forms of A-Beta peptide. Our results confirmed TTR as a protective molecule in AD, and prompted A-Beta proteolysis by TTR as a protective mechanism in this disease. TTR may prove to be a useful therapeutic agent for preventing or retarding the cerebral amyloid plaque formation implicated in AD pathology.

  11. Immunotherapy of Alzheimer's disease (AD): from murine models to anti-amyloid beta (Abeta) human monoclonal antibodies.

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    Geylis, Valeria; Steinitz, Michael

    2006-01-01

    The deposition of amyloid beta (Abeta) protein is a key pathological feature in Alzheimer's disease (AD). In murine models of AD, both active and passive immunization against Abeta induce a marked reduction in amyloid brain burden and an improvement in cognitive functions. Preliminary results of a prematurely terminated clinical trial where AD patients were actively vaccinated with aggregated Abeta bear resemblance to those documented in murine models. Passive immunization of AD patients with anti-Abeta antibodies, in particular human antibodies, is a strategy that provides a more cautious management and control of any undesired side effects. Sera of all healthy adults contain anti-Abeta IgG autoimmune antibodies. Hence antigen-committed human B-cells are easily immortalized by Epstein-Barr virus (EBV) into anti-Abeta secreting cell lines. Two anti-Abeta human monoclonal antibodies which we recently prepared bind to the N-terminus of Abeta peptide and were shown to stain amyloid plaques in non-fixed brain sections from an AD patient. It is anticipated that specifically selected anti-Abeta human monoclonal antibodies could reduce and inhibit deposits of amyloid in brain while avoiding the cognitive decline that characterizes AD. In the future, this type of antibody may prove to be a promising immune therapy for the disease.

  12. Microglial responses to amyloid β peptide opsonization and indomethacin treatment

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    Leonard Brian

    2005-08-01

    Full Text Available Abstract Background Recent studies have suggested that passive or active immunization with anti-amyloid β peptide (Aβ antibodies may enhance microglial clearance of Aβ deposits from the brain. However, in a human clinical trial, several patients developed secondary inflammatory responses in brain that were sufficient to halt the study. Methods We have used an in vitro culture system to model the responses of microglia, derived from rapid autopsies of Alzheimer's disease patients, to Aβ deposits. Results Opsonization of the deposits with anti-Aβ IgG 6E10 enhanced microglial chemotaxis to and phagocytosis of Aβ, as well as exacerbated microglial secretion of the pro-inflammatory cytokines TNF-α and IL-6. Indomethacin, a common nonsteroidal anti-inflammatory drug (NSAID, had no effect on microglial chemotaxis or phagocytosis, but did significantly inhibit the enhanced production of IL-6 after Aβ opsonization. Conclusion These results are consistent with well known, differential NSAID actions on immune cell functions, and suggest that concurrent NSAID administration might serve as a useful adjunct to Aβ immunization, permitting unfettered clearance of Aβ while dampening secondary, inflammation-related adverse events.

  13. Absence of beta-amyloid in cortical cataracts of donors with and without Alzheimer's disease.

    Science.gov (United States)

    Michael, Ralph; Rosandić, Jurja; Montenegro, Gustavo A; Lobato, Elvira; Tresserra, Francisco; Barraquer, Rafael I; Vrensen, Gijs F J M

    2013-01-01

    Eye lenses from human donors with and without Alzheimer's disease (AD) were studied to evaluate the presence of amyloid in cortical cataract. We obtained 39 lenses from 21 postmortem donors with AD and 15 lenses from age-matched controls provided by the Banco de Ojos para Tratamientos de la Ceguera (Barcelona, Spain). For 17 donors, AD was clinically diagnosed by general physicians and for 4 donors the AD diagnosis was neuropathologically confirmed. Of the 21 donors with AD, 6 had pronounced bilateral cortical lens opacities and 15 only minor or no cortical opacities. As controls, 7 donors with pronounced cortical opacities and 8 donors with almost transparent lenses were selected. All lenses were photographed in a dark field stereomicroscope. Histological sections were analyzed using a standard and a more sensitive Congo red protocol, thioflavin staining and beta-amyloid immunohistochemistry. Brain tissue from two donors, one with cerebral amyloid angiopathy and another with advanced AD-related changes and one cornea with lattice dystrophy were used as positive controls for the staining techniques. Thioflavin, standard and modified Congo red staining were positive in the control brain tissues and in the dystrophic cornea. Beta-amyloid immunohistochemistry was positive in the brain tissues but not in the cornea sample. Lenses from control and AD donors were, without exception, negative after Congo red, thioflavin, and beta-amyloid immunohistochemical staining. The results of the positive control tissues correspond well with known observations in AD, amyloid angiopathy and corneas with lattice dystrophy. The absence of staining in AD and control lenses with the techniques employed lead us to conclude that there is no beta-amyloid in lenses from donors with AD or in control cortical cataracts. The inconsistency with previous studies of Goldstein et al. (2003) and Moncaster et al. (2010), both of which demonstrated positive Congo red, thioflavin, and beta-amyloid

  14. Intracellular accumulation of amyloid-beta - a predictor for synaptic dysfunction and neuron loss in Alzheimer's disease

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    Thomas A Bayer

    2010-03-01

    Full Text Available Despite of long-standing evidence that beta-amyloid (Aβ peptides have detrimental effects on synaptic function, the relationship between Aβ, synaptic and neuron loss is largely unclear. During the last years there is growing evidence that early intraneuronal accumulation of Aβ peptides is one of the key events leading to synaptic and neuronal dysfunction. Many studies have been carried out using transgenic mouse models of Alzheimer’s disease (AD which have been proven to be valuable model system in modern AD research. The present review discusses the impact of intraneuronal Aβ accumulation on synaptic impairment and neuron loss and provides an overview of currently available AD mouse models showing these pathological alterations.

  15. Peptide p5 binds both heparinase-sensitive glycosaminoglycans and fibrils in patient-derived AL amyloid extracts

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Emily B.; Williams, Angela [Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Heidel, Eric [Department of Surgery, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Macy, Sallie [Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Kennel, Stephen J. [Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Department of Radiology, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Wall, Jonathan S., E-mail: jwall@utmck.edu [Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Department of Radiology, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States)

    2013-06-21

    Highlights: •Polybasic peptide p5 binds human light chain amyloid extracts. •The binding of p5 with amyloid involves both glycosaminoglycans and fibrils. •Heparinase treatment led to a correlation between p5 binding and fibril content. •p5 binding to AL amyloid requires electrostatic interactions. -- Abstract: In previously published work, we have described heparin-binding synthetic peptides that preferentially recognize amyloid deposits in a mouse model of reactive systemic (AA) amyloidosis and can be imaged by using positron and single photon emission tomographic imaging. We wanted to extend these findings to the most common form of visceral amyloidosis, namely light chain (AL); however, there are no robust experimental animal models of AL amyloidosis. To further define the binding of the lead peptide, p5, to AL amyloid, we characterized the reactivity in vitro of p5 with in situ and patient-derived AL amyloid extracts which contain both hypersulfated heparan sulfate proteoglycans as well as amyloid fibrils. Histochemical staining demonstrated that the peptide specifically localized with tissue-associated AL amyloid deposits. Although we anticipated that p5 would undergo electrostatic interactions with the amyloid-associated glycosaminoglycans expressing heparin-like side chains, no significant correlation between peptide binding and glycosaminoglycan content within amyloid extracts was observed. In contrast, following heparinase I treatment, although overall binding was reduced, a positive correlation between peptide binding and amyloid fibril content became evident. This interaction was further confirmed using synthetic light chain fibrils that contain no carbohydrates. These data suggest that p5 can bind to both the sulfated glycosaminoglycans and protein fibril components of AL amyloid. Understanding these complex electrostatic interactions will aid in the optimization of synthetic peptides for use as amyloid imaging agents and potentially as

  16. The proton-pump inhibitor lansoprazole enhances amyloid beta production.

    Science.gov (United States)

    Badiola, Nahuai; Alcalde, Victor; Pujol, Albert; Münter, Lisa-Marie; Multhaup, Gerd; Lleó, Alberto; Coma, Mireia; Soler-López, Montserrat; Aloy, Patrick

    2013-01-01

    A key event in the pathogenesis of Alzheimer's disease (AD) is the accumulation of amyloid-β (Aβ) species in the brain, derived from the sequential cleavage of the amyloid precursor protein (APP) by β- and γ-secretases. Based on a systems biology study to repurpose drugs for AD, we explore the effect of lansoprazole, and other proton-pump inhibitors (PPIs), on Aβ production in AD cellular and animal models. We found that lansoprazole enhances Aβ37, Aβ40 and Aβ42 production and lowers Aβ38 levels on amyloid cell models. Interestingly, acute lansoprazole treatment in wild type and AD transgenic mice promoted higher Aβ40 levels in brain, indicating that lansoprazole may also exacerbate Aβ production in vivo. Overall, our data presents for the first time that PPIs can affect amyloid metabolism, both in vitro and in vivo.

  17. [Development of anti-Alzheimer's disease drug based on beta-amyloid hypothesis].

    Science.gov (United States)

    Sugimoto, Hachiro

    2010-04-01

    Currently, there are five anti-Alzheimer's disease drugs approved. These are tacrine, donepezil, rivastigmine, galantamine, and memantine. The mechanism of the first four drugs is acetylcholinesterase inhibition, while memantine is an NMDA-receptor antagonist. However, these drugs do not cure Alzheimer's, but are only symptomatic treatments. Therefore, a cure for Alzheimer's disease is truly needed. Alzheimer's disease is a progressive neurodegenerative disease characterized by cognitive deficits. The cause of the disease is not well understood, but research indicates that the aggregation of beta-amyloid is the fundamental cause. This theory suggests that beta-amyloid aggregation causes neurotoxicity. Therefore, development of the next anti-Alzheimer's disease drug is based on the beta-amyloid theory. We are now studying natural products, such as mulberry leaf extracts and curcumin derivatives, as potential cure for Alzheimer's disease. In this report, we describe some data about these natural products and derivatives.

  18. Amyloid-beta transporter expression at the blood-CSF barrier is age-dependent

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    Pascale Crissey L

    2011-07-01

    Full Text Available Abstract Background Age is the major risk factor for many neurodegenerative diseases, including Alzheimer's disease (AD. There is an accumulation of amyloid-beta peptides (Aβ in both the AD brain and the normal aging brain. Clearance of Aβ from the brain occurs via active transport at the blood-brain barrier (BBB and blood-cerebrospinal fluid barrier (BCSFB. With increasing age, the expression of the Aβ efflux transporters is decreased and the Aβ influx transporter expression is increased at the BBB, adding to the amyloid burden in the brain. Expression of the Aβ transporters at the choroid plexus (CP epithelium as a function of aging was the subject of this study. Methods This project investigated the changes in expression of the Aβ transporters, the low density lipoprotein receptor-related protein-1 (LRP-1, P-glycoprotein (P-gp, LRP-2 (megalin and the receptor for advanced glycation end-products (RAGE at the BCSFB in Brown-Norway/Fischer rats at ages 3, 6, 9, 12, 20, 30 and 36 months, using real time RT-PCR to measure transporter mRNA expression, and immunohistochemistry (IHC to measure transporter protein in isolated rat CP. Results There was an increase in the transcription of the Aβ efflux transporters, LRP-1 and P-gp, no change in RAGE expression and a decrease in LRP-2, the CP epithelium influx transporter, at the BCSFB with aging. Decreased Aβ42 concentration in the CP, as measured by quantitative IHC, was associated with these Aβ transporter alterations. Conclusions Age-dependent alterations in the CP Aβ transporters are associated with a decrease in Aβ42 accumulation in the CP, and are reciprocal to the changes seen in these transporters at the BBB, suggesting a possible compensatory role for the BCSFB in Aβ clearance in aging.

  19. Red mold rice ameliorates impairment of memory and learning ability in intracerebroventricular amyloid beta-infused rat by repressing amyloid beta accumulation.

    Science.gov (United States)

    Lee, Chun-Lin; Kuo, Tzong-Fu; Wang, Jyh-Jye; Pan, Tzu-Ming

    2007-11-01

    Amyloid beta (Abeta) peptide related to the onset of Alzheimer's disease (AD) damaged neurons and further resulted in dementia. Monascus-fermented red mold rice (RMR), a traditional Chinese medicine as well as health food, includes monacolins (with the same function as statins) and multifunctional metabolites. In this study, ethanol extract of RMR (RE) was used to evaluate neuroprotection against Abeta40 neurotoxicity in PC12 cells. Furthermore, the effects of dietary administration of RMR on memory and learning abilities are confirmed in an animal model of AD rats infused with Abeta40 into the cerebral ventricle. During continuous Abeta40 infusion for 28 days, the rats of test groups were administered RMR or lovastatin. Memory and learning abilities were evaluated in the water maze and passive avoidance tasks. After sacrifice, cerebral cortex and hippocampus were collected for the examination of AD risk factors. The in vitro results clearly indicate that RE provides stronger neuroprotection in rescuing cell viability as well as repressing inflammatory response and oxidative stress. RMR administration potently reverses the memory deficit in the memory task. Abeta40 infusion increases acetylcholinesterase activity, reactive oxygen species, and lipid peroxidation and decreases total antioxidant status and superoxide dismutase activity in brain, but these damages were potently reversed by RMR administration, and the protection was more significant than that with lovastatin administration. The protection provided by RMR is able to prevent Abeta fibrils from being formed and deposited in hippocampus and further decrease Abeta40 accumulation, even though Abeta40 solution was infused into brain continuously. (c) 2007 Wiley-Liss, Inc.

  20. Methods for labeling .beta.-amyloid plaques and neurofibrillary tangles

    Science.gov (United States)

    Barrio, Jorge R.; Petric, Andrej; Satyamurthy, Nagichettiar; Small, Gary W.; Cole, Gregory M.; Huang, Sung-Cheng

    2001-01-01

    A method for labeling .beta.-amyloid plaques and neurofibrillary tangles in vivo and in vitro, comprises contacting a compound of formula (I): ##STR1## with mammalian tissue. In formula (I), R.sub.1 is selected from the group consisting of --C(O)-alkyl, --C(O)-alkylenyl-R.sub.4, --C(O)O-alkyl, --C(O)O-alkylenyl-R.sub.4, --C.dbd.C(CN).sub.2 -alkyl, --C.dbd.C(CN).sub.2 -alkylenyl-R.sub.4 , ##STR2## R.sub.4 is a radical selected from the group consisting of alkyl, substituted alkyl, aryl and substituted aryl; R.sub.5, is a radical selected from the group consisting of --NH.sub.2, --OH, --SH, --NH-alkyl, --NHR.sub.4, --NH-alkylenyl-R.sub.4, --O-alkyl, --O-alkylenyl-R.sub.4, --S-alkyl, and --S-alkylenyl-R.sub.4 ; R.sub.6 is a radical selected from the group consisting of --CN, --COOH, --C(O)O-alkyl, --C(O)O-alkylenyl-R.sub.4, --C(O)-alkyl, --C(O)-alkylenyl-R.sub.4, --C(O)-halogen, --C(O)NH , --C(O)NH-alkyl, --C(O)NH-alkylenyl-R.sub.4 ; R.sub.7 is a radical selected from the group consisting of O, NH, and S; and R.sub.8 is N, O or S. R.sub.2 and R.sub.3 are each independently selected from the group consisting of alkyl and alkylenyl-R.sub.10, wherein R.sub.10 is selected from the group consisting of --OH, --OTs, halogen, spiperone, spiperone ketal and spiperone-3-yl. Alternatively, R.sub.2 and R.sub.3 together form a heterocyclic ring, optionally substituted with at least one radical selected from the group consisting of alkyl, alkoxy, OH, OTs, halogen, alkylenyl-R.sub.10, carbonyl, spiperone, spiperone ketal and spiperone-3-yl. In the compounds of formula (I), one or more of the hydrogen, halogen or carbon atoms can, optionally, be replaced with a radiolabel.

  1. Compositions for labeling .beta.-amyloid plaques and neurofibrillary tangles

    Science.gov (United States)

    Barrio, Jorge R [Agoura Hills, CA; Petric, Andrej [Ljubljana, SI; Satyamurthy, Nagichettiar [Los Angeles, CA; Small, Gary W [Los Angeles, CA; Cole, Gregory M [Santa Monica, CA; Huang, Sung-Cheng [Sherman Oaks, CA

    2008-03-11

    Compositions useful for labeling .beta.-amyloid plaques and neurofibrillary tangles are provided. The compositions comprises compounds of formula (I): ##STR00001## wherein R.sub.1 is selected from the group consisting of --C(O)-alkyl, --C(O)-alkylenyl-R.sub.4, --C(O)O-alkyl, --C(O)O-alkylenyl-R.sub.4, --C.dbd.C(CN).sub.2-alkyl, --C.dbd.C(CN).sub.2-alkylenyl-R.sub.4, ##STR00002## wherein R.sub.4 is a radical selected from the group consisting of alkyl, substituted alkyl, aryl and substituted aryl; R.sub.5 is a radical selected from the group consisting of --NH.sub.2, --OH, --SH, --NH-alkyl, --NHR.sub.4, --NH-alkylenyl-R.sub.4, --O-alkyl, --O-alkylenyl-R.sub.4, --S-alkyl, and --S-alkylenyl-R.sub.4; R.sub.6 is a radical selected from the group consisting of --CN, --COOH, --C(O)O-alkyl, --C(O)O-alkylenyl-R.sub.4, --C(O)-alkyl, --C(O)-alkylenyl-R.sub.4, --C(O)-halogen, --C(O)NH-alkyl, --C(O)NH-alkylenyl-R.sub.4 and --C(O)NH.sub.2; R.sub.7 is a radical selected from the group consisting of O, NH, and S; and R.sub.8 is N, O or S; and R.sub.2 is selected from the group consisting of alkyl and alkylenyl-R.sub.10 and R.sub.3 is alkylenyl-R.sub.10, wherein R.sub.10 is selected from the group consisting of --OH, --OTs, halogen, spiperone, spiperone ketal, and spiperone-3-yl, or R.sub.2 and R.sub.3 together form a heterocyclic ring, optionally substituted with at least one radical selected from the group consisting of alkyl, alkoxy, OH, OTs, halogen, alkyl-R.sub.10, carbonyl, spiperone, spiperone ketal and spiperone-3-yl, and further wherein one or more of the hydrogen, halogen or carbon atoms are optionally replaced with a radiolabel.

  2. Amyloid Beta and Tau as Alzheimer's Disease Blood Biomarkers: Promise From New Technologies.

    Science.gov (United States)

    Lue, Lih-Fen; Guerra, Andre; Walker, Douglas G

    2017-07-01

    The utility of the levels of amyloid beta (Aβ) peptide and tau in blood for diagnosis, drug development, and assessment of clinical trials for Alzheimer's disease (AD) has not been established. The lack of availability of ultra-sensitive assays is one critical issue that has impeded progress. The levels of Aβ species and tau in plasma and serum are much lower than levels in cerebrospinal fluid. Furthermore, plasma or serum contain high levels of assay-interfering factors, resulting in difficulties in the commonly used singulex or multiplex ELISA platforms. In this review, we focus on two modern immune-complex-based technologies that show promise to advance this field. These innovative technologies are immunomagnetic reduction technology and single molecule array technology. We describe the technologies and discuss the published studies using these technologies. Currently, the potential of utilizing these technologies to advance Aβ and tau as blood-based biomarkers for AD requires further validation using already collected large sets of samples, as well as new cohorts and population-based longitudinal studies.

  3. Detection of Alzheimer’s disease amyloid-beta plaque deposition by deep brain impedance profiling

    Science.gov (United States)

    Béduer, Amélie; Joris, Pierre; Mosser, Sébastien; Fraering, Patrick C.; Renaud, Philippe

    2015-04-01

    Objective. Alzheimer disease (AD) is the most common form of neurodegenerative disease in elderly people. Toxic brain amyloid-beta (Aß) aggregates and ensuing cell death are believed to play a central role in the pathogenesis of the disease. In this study, we investigated if we could monitor the presence of these aggregates by performing in situ electrical impedance spectroscopy measurements in AD model mice brains. Approach. In this study, electrical impedance spectroscopy measurements were performed post-mortem in APPPS1 transgenic mice brains. This transgenic model is commonly used to study amyloidogenesis, a pathological hallmark of AD. We used flexible probes with embedded micrometric electrodes array to demonstrate the feasibility of detecting senile plaques composed of Aß peptides by localized impedance measurements. Main results. We particularly focused on deep brain structures, such as the hippocampus. Ex vivo experiments using brains from young and old APPPS1 mice lead us to show that impedance measurements clearly correlate with the percentage of Aβ plaque load in the brain tissues. We could monitor the effects of aging in the AD APPPS1 mice model. Significance. We demonstrated that a localized electrical impedance measurement constitutes a valuable technique to monitor the presence of Aβ-plaques, which is complementary with existing imaging techniques. This method does not require prior Aβ staining, precluding the risk of variations in tissue uptake of dyes or tracers, and consequently ensuring reproducible data collection.

  4. A kinetic model for beta-amyloid adsorption at the air/solution interface and its implication to the beta-amyloid aggregation process.

    Science.gov (United States)

    Jiang, Dianlu; Dinh, Kim Lien; Ruthenburg, Travis C; Zhang, Yi; Su, Lei; Land, Donald P; Zhou, Feimeng

    2009-03-12

    At the air/buffer solution interface the kinetics of adsorption of amyloid beta peptide, Abeta(1-42), whose bulk concentration (submicromolar) is more than 2 orders of magnitude lower than that typically used in other in vitro aggregation studies, has been studied using a Langmuir-Blodgett trough. The pressure-time curves exhibit a lag phase, wherein the surface pressure essentially remains at zero, and a rising phase, corresponding to the Abeta adsorption at the interface. The duration of the lag phase was found to be highly dependent on both the Abeta bulk concentration and the solution temperature. A large activation energy (62.2 +/- 4.1 KJ/mol) was determined and the apparent adsorption rate constant was found to be linearly dependent on the Abeta bulk concentration. Attenuated total reflection-IR spectra of the adsorbed Abeta transferred to a solid substrate and circular dichroism measurements of Abeta in the solution layer near the interface reveal that the natively unstructured Abeta in the bulk undergo a conformation change (folding) to mainly the alpha-helical structure. The results suggest that, prior to the adsorption step, an equilibrium between Abeta conformations is established within the subsurface. The kinetic equation derived from this model confirms that the overall Abeta adsorption is kinetically controlled and the apparent rate constant is proportional to the Abeta bulk concentration. This model also indicates that interfaces such as cell membranes and lipid bilayers may facilitate Abeta aggregation/ fibrillation by providing a thin hydrophobic layer adjacent to the interface for the initial A/beta conformation change (misfolding) and accumulation. Such a preconcentration effect offers a plausible explanation of the fact that Abeta fibrillation occurs in vivo at nanomolar concentrations. Another important biological implication from our work is that Abeta misfolding may occur before its adsorption onto a cell membrane. This general kinetic model

  5. Amyloid-beta aggregates cause alterations of astrocytic metabolic phenotype: impact on neuronal viability.

    Science.gov (United States)

    Allaman, Igor; Gavillet, Mathilde; Bélanger, Mireille; Laroche, Thierry; Viertl, David; Lashuel, Hilal A; Magistretti, Pierre J

    2010-03-03

    Amyloid-beta (Abeta) peptides play a key role in the pathogenesis of Alzheimer's disease and exert various toxic effects on neurons; however, relatively little is known about their influence on glial cells. Astrocytes play a pivotal role in brain homeostasis, contributing to the regulation of local energy metabolism and oxidative stress defense, two aspects of importance for neuronal viability and function. In the present study, we explored the effects of Abeta peptides on glucose metabolism in cultured astrocytes. Following Abeta(25-35) exposure, we observed an increase in glucose uptake and its various metabolic fates, i.e., glycolysis (coupled to lactate release), tricarboxylic acid cycle, pentose phosphate pathway, and incorporation into glycogen. Abeta increased hydrogen peroxide production as well as glutathione release into the extracellular space without affecting intracellular glutathione content. A causal link between the effects of Abeta on glucose metabolism and its aggregation and internalization into astrocytes through binding to members of the class A scavenger receptor family could be demonstrated. Using astrocyte-neuron cocultures, we observed that the overall modifications of astrocyte metabolism induced by Abeta impair neuronal viability. The effects of the Abeta(25-35) fragment were reproduced by Abeta(1-42) but not by Abeta(1-40). Finally, the phosphoinositide 3-kinase (PI3-kinase) pathway appears to be crucial in these events since both the changes in glucose utilization and the decrease in neuronal viability are prevented by LY294002, a PI3-kinase inhibitor. This set of observations indicates that Abeta aggregation and internalization into astrocytes profoundly alter their metabolic phenotype with deleterious consequences for neuronal viability.

  6. Elucidation of amyloid beta-protein oligomerization mechanisms: discrete molecular dynamics study.

    Science.gov (United States)

    Urbanc, B; Betnel, M; Cruz, L; Bitan, G; Teplow, D B

    2010-03-31

    Oligomers of amyloid beta-protein (Abeta) play a central role in the pathology of Alzheimer's disease. Of the two predominant Abeta alloforms, Abeta(1-40) and Abeta(1-42), Abeta(1-42) is more strongly implicated in the disease. We elucidated the structural characteristics of oligomers of Abeta(1-40) and Abeta(1-42) and their Arctic mutants, [E22G]Abeta(1-40) and [E22G]Abeta(1-42). We simulated oligomer formation using discrete molecular dynamics (DMD) with a four-bead protein model, backbone hydrogen bonding, and residue-specific interactions due to effective hydropathy and charge. For all four peptides under study, we derived the characteristic oligomer size distributions that were in agreement with prior experimental findings. Unlike Abeta(1-40), Abeta(1-42) had a high propensity to form paranuclei (pentameric or hexameric) structures that could self-associate into higher-order oligomers. Neither of the Arctic mutants formed higher-order oligomers, but [E22G]Abeta(1-40) formed paranuclei with a similar propensity to that of Abeta(1-42). Whereas the best agreement with the experimental data was obtained when the charged residues were modeled as solely hydrophilic, further assembly from spherical oligomers into elongated protofibrils was induced by nonzero electrostatic interactions among the charged residues. Structural analysis revealed that the C-terminal region played a dominant role in Abeta(1-42) oligomer formation whereas Abeta(1-40) oligomerization was primarily driven by intermolecular interactions among the central hydrophobic regions. The N-terminal region A2-F4 played a prominent role in Abeta(1-40) oligomerization but did not contribute to the oligomerization of Abeta(1-42) or the Arctic mutants. The oligomer structure of both Arctic peptides resembled Abeta(1-42) more than Abeta(1-40), consistent with their potentially more toxic nature.

  7. Insulin inhibits amyloid beta-induced cell death in cultured human brain pericytes

    NARCIS (Netherlands)

    Rensink, Annemieke A M; Otte-Höller, Irene; de Boer, Roelie; Bosch, Remko R; ten Donkelaar, Hans J; de Waal, Robert M W; Verbeek, Marcel M; Kremer, Berry

    Amyloid-beta (Abeta) deposition in the cerebral arterial and capillary walls is one of the characteristics of Alzheimer's disease and hereditary cerebral hemorrhage with amyloidosis-Dutch type. In vitro, Abeta1-40, carrying the "Dutch" mutation (DAbeta1-40), induced reproducible degeneration of

  8. Loss of function of ATXN1 increases amyloid beta-protein levels by potentiating beta-secretase processing of beta-amyloid precursor protein.

    Science.gov (United States)

    Zhang, Can; Browne, Andrew; Child, Daniel; Divito, Jason R; Stevenson, Jesse A; Tanzi, Rudolph E

    2010-03-19

    Alzheimer disease (AD) is a devastating neurodegenerative disease with complex and strong genetic inheritance. Four genes have been established to either cause familial early onset AD (APP, PSEN1, and PSEN2) or to increase susceptibility for late onset AD (APOE). To date approximately 80% of the late onset AD genetic variance remains elusive. Recently our genome-wide association screen identified four novel late onset AD candidate genes. Ataxin 1 (ATXN1) is one of these four AD candidate genes and has been indicated to be the disease gene for spinocerebellar ataxia type 1, which is also a neurodegenerative disease. Mounting evidence suggests that the excessive accumulation of Abeta, the proteolytic product of beta-amyloid precursor protein (APP), is the primary AD pathological event. In this study, we ask whether ATXN1 may lead to AD pathogenesis by affecting Abeta and APP processing utilizing RNA interference in a human neuronal cell model and mouse primary cortical neurons. We show that knock-down of ATXN1 significantly increases the levels of both Abeta40 and Abeta42. This effect could be rescued with concurrent overexpression of ATXN1. Moreover, overexpression of ATXN1 decreased Abeta levels. Regarding the underlying molecular mechanism, we show that the effect of ATXN1 expression on Abeta levels is modulated via beta-secretase cleavage of APP. Taken together, ATXN1 functions as a genetic risk modifier that contributes to AD pathogenesis through a loss-of-function mechanism by regulating beta-secretase cleavage of APP and Abeta levels.

  9. Uptake of raft components into amyloid β-peptide aggregates and membrane damage.

    Science.gov (United States)

    Sasahara, Kenji; Morigaki, Kenichi; Mori, Yasuko

    2015-07-15

    Amyloid aggregation and deposition of amyloid β-peptide (Aβ) are pathologic characteristics of Alzheimer's disease (AD). Recent reports have shown that the association of Aβ with membranes containing ganglioside GM1 (GM1) plays a pivotal role in amyloid deposition and the pathogenesis of AD. However, the molecular interactions responsible for membrane damage associated with Aβ deposition are not fully understood. In this study, we microscopically observed amyloid aggregation of Aβ in the presence of lipid vesicles and on a substrate-supported planar membrane containing raft components and GM1. The experimental system enabled us to observe lipid-associated aggregation of Aβ, uptake of the raft components into Aβ aggregates, and relevant membrane damage. The results indicate that uptake of raft components from the membrane into Aβ deposits induces macroscopic heterogeneity of the membrane structure. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Glutamate system, amyloid β peptides and tau protein: functional interrelationships and relevance to Alzheimer disease pathology

    Science.gov (United States)

    Revett, Timothy J.; Baker, Glen B.; Jhamandas, Jack; Kar, Satyabrata

    2013-01-01

    Alzheimer disease is the most prevalent form of dementia globally and is characterized premortem by a gradual memory loss and deterioration of higher cognitive functions and postmortem by neuritic plaques containing amyloid β peptide and neurofibrillary tangles containing phospho-tau protein. Glutamate is the most abundant neurotransmitter in the brain and is essential to memory formation through processes such as long-term potentiation and so might be pivotal to Alzheimer disease progression. This review discusses how the glutamatergic system is impaired in Alzheimer disease and how interactions of amyloid β and glutamate influence synaptic function, tau phosphorylation and neurodegeneration. Interestingly, glutamate not only influences amyloid β production, but also amyloid β can alter the levels of glutamate at the synapse, indicating that small changes in the concentrations of both molecules could influence Alzheimer disease progression. Finally, we describe how the glutamate receptor antagonist, memantine, has been used in the treatment of individuals with Alzheimer disease and discuss its effectiveness. PMID:22894822

  11. Manipulation of self-assembly amyloid peptide nanotubes by dielectrophoresis (DEP)

    DEFF Research Database (Denmark)

    Castillo, Jaime; Tanzi, Simone; Dimaki, Maria

    2008-01-01

    Self-assembled amyloid peptide nanotubes (SAPNT) were manipulated and immobilized using dielectrophoresis. Micro-patterned electrodes of Au were fabricated by photolithography and lifted off on a silicon dioxide layer. SAPNT were manipulated by adjusting the amplitude and frequency of the applied...

  12. Halogenation dictates the architecture of amyloid peptide nanostructures† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7nr03263c

    Science.gov (United States)

    Pizzi, Andrea; Pigliacelli, Claudia; Gori, Alessandro; Nonappa; Ikkala, Olli; Demitri, Nicola; Terraneo, Giancarlo; Castelletto, Valeria; Hamley, Ian W.; Baldelli Bombelli, Francesca

    2017-01-01

    Amyloid peptides yield a plethora of interesting nanostructures though difficult to control. Here we report that depending on the number, position, and nature of the halogen atoms introduced into either one or both phenylalanine benzene rings of the amyloid β peptide-derived core-sequence KLVFF, four different architectures were obtained in a controlled manner. Our findings demonstrate that halogenation may develop as a general strategy to engineer amyloidal peptide self-assembly and obtain new amyloidal nanostructures. PMID:28696473

  13. 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.

  14. A binding-site barrier affects imaging efficiency of high affinity amyloid-reactive peptide radiotracers in vivo.

    Science.gov (United States)

    Wall, Jonathan S; Williams, Angela; Richey, Tina; Stuckey, Alan; Huang, Ying; Wooliver, Craig; Macy, Sallie; Heidel, Eric; Gupta, Neil; Lee, Angela; Rader, Brianna; Martin, Emily B; Kennel, Stephen J

    2013-01-01

    Amyloid is a complex pathology associated with a growing number of diseases including Alzheimer's disease, type 2 diabetes, rheumatoid arthritis, and myeloma. The distribution and extent of amyloid deposition in body organs establishes the prognosis and can define treatment options; therefore, determining the amyloid load by using non-invasive molecular imaging is clinically important. We have identified a heparin-binding peptide designated p5 that, when radioiodinated, was capable of selectively imaging systemic visceral AA amyloidosis in a murine model of the disease. The p5 peptide was posited to bind effectively to amyloid deposits, relative to similarly charged polybasic heparin-reactive peptides, because it adopted a polar α helix secondary structure. We have now synthesized a variant, p5R, in which the 8 lysine amino acids of p5 have been replaced with arginine residues predisposing the peptide toward the α helical conformation in an effort to enhance the reactivity of the peptide with the amyloid substrate. The p5R peptide had higher affinity for amyloid and visualized AA amyloid in mice by using SPECT/CT imaging; however, the microdistribution, as evidenced in micro-autoradiographs, was dramatically altered relative to the p5 peptide due to its increased affinity and a resultant "binding site barrier" effect. These data suggest that radioiodinated peptide p5R may be optimal for the in vivo detection of discreet, perivascular amyloid, as found in the brain and pancreatic vasculature, by using molecular imaging techniques; however, peptide p5, due to its increased penetration, may yield more quantitative imaging of expansive tissue amyloid deposits.

  15. A binding-site barrier affects imaging efficiency of high affinity amyloid-reactive peptide radiotracers in vivo.

    Directory of Open Access Journals (Sweden)

    Jonathan S Wall

    Full Text Available Amyloid is a complex pathology associated with a growing number of diseases including Alzheimer's disease, type 2 diabetes, rheumatoid arthritis, and myeloma. The distribution and extent of amyloid deposition in body organs establishes the prognosis and can define treatment options; therefore, determining the amyloid load by using non-invasive molecular imaging is clinically important. We have identified a heparin-binding peptide designated p5 that, when radioiodinated, was capable of selectively imaging systemic visceral AA amyloidosis in a murine model of the disease. The p5 peptide was posited to bind effectively to amyloid deposits, relative to similarly charged polybasic heparin-reactive peptides, because it adopted a polar α helix secondary structure. We have now synthesized a variant, p5R, in which the 8 lysine amino acids of p5 have been replaced with arginine residues predisposing the peptide toward the α helical conformation in an effort to enhance the reactivity of the peptide with the amyloid substrate. The p5R peptide had higher affinity for amyloid and visualized AA amyloid in mice by using SPECT/CT imaging; however, the microdistribution, as evidenced in micro-autoradiographs, was dramatically altered relative to the p5 peptide due to its increased affinity and a resultant "binding site barrier" effect. These data suggest that radioiodinated peptide p5R may be optimal for the in vivo detection of discreet, perivascular amyloid, as found in the brain and pancreatic vasculature, by using molecular imaging techniques; however, peptide p5, due to its increased penetration, may yield more quantitative imaging of expansive tissue amyloid deposits.

  16. Curcumin Decreases AmyloidPeptide Levels by Attenuating the Maturation of Amyloid-β Precursor Protein*

    Science.gov (United States)

    Zhang, Can; Browne, Andrew; Child, Daniel; Tanzi, Rudolph E.

    2010-01-01

    Alzheimer disease (AD) is a devastating neurodegenerative disease with no cure. The pathogenesis of AD is believed to be driven primarily by amyloid-β (Aβ), the principal component of senile plaques. Aβ is an ∼4-kDa peptide generated via cleavage of the amyloid-β precursor protein (APP). Curcumin is a compound in the widely used culinary spice, turmeric, which possesses potent and broad biological activities, including anti-inflammatory and antioxidant activities, chemopreventative effects, and effects on protein trafficking. Recent in vivo studies indicate that curcumin is able to reduce Aβ-related pathology in transgenic AD mouse models via unknown molecular mechanisms. Here, we investigated the effects of curcumin on Aβ levels and APP processing in various cell lines and mouse primary cortical neurons. We show for the first time that curcumin potently lowers Aβ levels by attenuating the maturation of APP in the secretory pathway. These data provide a mechanism of action for the ability of curcumin to attenuate amyloid-β pathology. PMID:20622013

  17. 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...

  18. DNA polymerase-beta is expressed early in neurons of Alzheimer's disease brain and is loaded into DNA replication forks in neurons challenged with beta-amyloid

    NARCIS (Netherlands)

    Copani, Agata; Hoozemans, Jeroen J. M.; Caraci, Filippo; Calafiore, Marco; van Haastert, Elise S.; Veerhuis, Robert; Rozemuller, Annemieke J. M.; Aronica, Eleonora; Sortino, Maria Angela; Nicoletti, Ferdinando

    2006-01-01

    Cultured neurons exposed to synthetic beta-amyloid (Abeta) fragments reenter the cell cycle and initiate a pathway of DNA replication that involves the repair enzyme DNA polymerase-beta (DNA pol-beta) before undergoing apoptotic death. In this study, by performing coimmunoprecipitation experiments

  19. First demonstration of cerebrospinal fluid and plasma A beta lowering with oral administration of a beta-site amyloid precursor protein-cleaving enzyme 1 inhibitor in nonhuman primates.

    Science.gov (United States)

    Sankaranarayanan, Sethu; Holahan, Marie A; Colussi, Dennis; Crouthamel, Ming-Chih; Devanarayan, Viswanath; Ellis, Joan; Espeseth, Amy; Gates, Adam T; Graham, Samuel L; Gregro, Allison R; Hazuda, Daria; Hochman, Jerome H; Holloway, Katharine; Jin, Lixia; Kahana, Jason; Lai, Ming-tain; Lineberger, Janet; McGaughey, Georgia; Moore, Keith P; Nantermet, Philippe; Pietrak, Beth; Price, Eric A; Rajapakse, Hemaka; Stauffer, Shaun; Steinbeiser, Melissa A; Seabrook, Guy; Selnick, Harold G; Shi, Xiao-Ping; Stanton, Matthew G; Swestock, John; Tugusheva, Katherine; Tyler, Keala X; Vacca, Joseph P; Wong, Jacky; Wu, Guoxin; Xu, Min; Cook, Jacquelynn J; Simon, Adam J

    2009-01-01

    beta-Site amyloid precursor protein (APP)-cleaving enzyme (BACE) 1 cleavage of amyloid precursor protein is an essential step in the generation of the potentially neurotoxic and amyloidogenic A beta 42 peptides in Alzheimer's disease. Although previous mouse studies have shown brain A beta lowering after BACE1 inhibition, extension of such studies to nonhuman primates or man was precluded by poor potency, brain penetration, and pharmacokinetics of available inhibitors. In this study, a novel tertiary carbinamine BACE1 inhibitor, tertiary carbinamine (TC)-1, was assessed in a unique cisterna magna ported rhesus monkey model, where the temporal dynamics of A beta in cerebrospinal fluid (CSF) and plasma could be evaluated. TC-1, a potent inhibitor (IC(50) approximately 0.4 nM), has excellent passive membrane permeability, low susceptibility to P-glycoprotein transport, and lowered brain A beta levels in a mouse model. Intravenous infusion of TC-1 led to a significant but transient lowering of CSF and plasma A beta levels in conscious rhesus monkeys because it underwent CYP3A4-mediated metabolism. Oral codosing of TC-1 with ritonavir, a potent CYP3A4 inhibitor, twice daily over 3.5 days in rhesus monkeys led to sustained plasma TC-1 exposure and a significant and sustained reduction in CSF sAPP beta, A beta 40, A beta 42, and plasma A beta 40 levels. CSF A beta 42 lowering showed an EC(50) of approximately 20 nM with respect to the CSF [TC-1] levels, demonstrating excellent concordance with its potency in a cell-based assay. These results demonstrate the first in vivo proof of concept of CSF A beta lowering after oral administration of a BACE1 inhibitor in a nonhuman primate.

  20. The Peptide Vaccine Combined with Prior Immunization of a Conventional Diphtheria-Tetanus Toxoid Vaccine Induced Amyloid β Binding Antibodies on Cynomolgus Monkeys and Guinea Pigs

    Directory of Open Access Journals (Sweden)

    Akira Yano

    2015-01-01

    Full Text Available The reduction of brain amyloid beta (Aβ peptides by anti-Aβ antibodies is one of the possible therapies for Alzheimer’s disease. We previously reported that the Aβ peptide vaccine including the T-cell epitope of diphtheria-tetanus combined toxoid (DT induced anti-Aβ antibodies, and the prior immunization with conventional DT vaccine enhanced the immunogenicity of the peptide. Cynomolgus monkeys were given the peptide vaccine subcutaneously in combination with the prior DT vaccination. Vaccination with a similar regimen was also performed on guinea pigs. The peptide vaccine induced anti-Aβ antibodies in cynomolgus monkeys and guinea pigs without chemical adjuvants, and excessive immune responses were not observed. Those antibodies could preferentially recognize Aβ40, and Aβ42 compared to Aβ fibrils. The levels of serum anti-Aβ antibodies and plasma Aβ peptides increased in both animals and decreased the brain Aβ40 level of guinea pigs. The peptide vaccine could induce a similar binding profile of anti-Aβ antibodies in cynomolgus monkeys and guinea pigs. The peptide vaccination could be expected to reduce the brain Aβ peptides and their toxic effects via clearance of Aβ peptides by generated antibodies.

  1. Apolipoproteins E and J interfere with amyloid-beta uptake by primary human astrocytes and microglia in vitro

    NARCIS (Netherlands)

    Mulder, S.D.; Nielsen, H.M.; Blankenstein, M.A.; Eikelenboom, P.; Veerhuis, R.

    2014-01-01

    Defective clearance of the amyloidpeptide (Aβ) from the brain is considered a strong promoter in Alzheimer's disease (AD) pathogenesis. Astrocytes and microglia are important mediators of Aβ clearance and Aβ aggregation state and the presence of amyloid associated proteins (AAPs), such as

  2. Structural and Thermodynamic Properties of AmyloidPeptides: Impact of Fragment Size

    Science.gov (United States)

    Kitahara, T.; Wise-Scira, O.; Coskuner, O.

    2010-10-01

    Alzheimer's disease is a progressive neurodegenerative disease whose physiological characteristics include the accumulation of amyloid-containing deposits in the brain and consequent synapse and neuron loss. Unfortunately, most widely used drugs for the treatment can palliate the outer symptoms but cannot cure the disease itself. Hence, developing a new drug that can cure it. Most recently, the ``early aggregation and monomer'' hypothesis has become popular and a few drugs have been developed based on this hypothesis. Detailed understanding of the amyloidpeptide structure can better help us to determine more effective treatment strategies; indeed, the structure of Amyloid has been studied extensively employing experimental and theoretical tools. Nevertheless, those studies have employed different fragment sizes of Amyloid and characterized its conformational nature in different media. Thus, the structural properties might be different from each other and provide a reason for the existing debates in the literature. Here, we performed all-atom MD simulations and present the structural and thermodynamic properties of Aβ1-16, Aβ1-28, and Aβ1-42 in the gas phase and in aqueous solution. Our studies show that the overall structures, secondary structures, and the calculated thermodynamic properties change with increasing peptide size. In addition, we find that the structural properties of those peptides are different from each other in the gas phase and in aqueous solution.

  3. A Binding-Site Barrier Affects Imaging Efficiency of High Affinity Amyloid-Reactive Peptide Radiotracers In Vivo

    OpenAIRE

    Wall, Jonathan S.; Williams, Angela; Richey, Tina; Stuckey, Alan; Huang, Ying; Wooliver, Craig; Macy, Sallie; Heidel, Eric; Gupta, Neil; Lee, Angela; Rader, Brianna; Martin, Emily B.; Kennel, Stephen J.

    2013-01-01

    Amyloid is a complex pathology associated with a growing number of diseases including Alzheimer's disease, type 2 diabetes, rheumatoid arthritis, and myeloma. The distribution and extent of amyloid deposition in body organs establishes the prognosis and can define treatment options; therefore, determining the amyloid load by using non-invasive molecular imaging is clinically important. We have identified a heparin-binding peptide designated p5 that, when radioiodinated, was capable of selecti...

  4. Emerging role of amyloid beta in stress response: Implication for depression and diabetes.

    Science.gov (United States)

    Morgese, Maria Grazia; Schiavone, Stefania; Trabace, Luigia

    2017-12-15

    Chronic stress is considered a widely accepted risk factor for the development of neuropsychiatric and neurological disorders. Indeed, high cortisol levels, and, thus, hypothalamic pituitary adrenal (HPA)-axis dysregulation, have been indicated as the most frequent alteration in patients affected by depression, as well as by Alzheimer's disease (AD). Furthermore, depressive state has been pointed as an early manifestation of AD, advocating an overlap between these neuropathological events. We have previously demonstrated that central soluble beta amyloid 1-42 (Aβ) administration peptide induces a depressive like-behavior in rats, with altered HPA axis activation, reduced cortical serotonin and neurotrophin levels. The crucial role of Aβ in stress response is becoming more and more evident, indeed many reports indicate that its release is increased in stressful conditions and stress-based paradigm. Furthermore, it has been reported that stress controls Aβ production and/or clearance. Chronic stress is responsible of inducing neuroinflammation processes and reduced serotoninergic tone, both pathophysiological mechanisms proposed in the association of depression with another chronic disease, such as diabetes. Likewise, AD has also been indicated as type 3 diabetes, considering the large body of literature that suggests common biological bases. Thus, the main aim of the present review is to evaluate the most recent literature findings in humans and animal models in regard to the role of Aβ in stress response and in relation to the biological substrates and pathological pathways common to AD and comorbid diseases, such as depression and diabetes. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Tuning the stereo-hindrance of a curcumin scaffold for the selective imaging of the soluble forms of amyloid beta species.

    Science.gov (United States)

    Li, Yuyan; Yang, Jian; Liu, Hongwu; Yang, Jing; Du, Lei; Feng, Haiwei; Tian, Yanli; Cao, Jianqin; Ran, Chongzhao

    2017-11-01

    Amyloid peptides and proteins are associated with the pathologies of numerous diseases. In the progression of a disease, amyloids exist in soluble and insoluble forms, which are the dominant species at different stages of the disease and they have different degrees of toxicity. However, differentiating between the soluble and insoluble forms is very challenging with small molecule probes due to multiple obstacles that need to be overcome. Inspired by the recognition principle of antibodies for sAβ, we hypothesized that the accessibility/tightness of soluble and insoluble amyloids could be utilized to design imaging probes to recognize different amyloid forms and the stereo-hindrance tuning strategy could be used to design imaging probes for selectively detecting the soluble amyloid beta (sAβ) species in Alzheimer's disease (AD). Herein, we demonstrated that tuning the stereo-hindrance of the phenoxy-alkyl chains at the 4-position of a curcumin scaffold could lead to certain selectivity for sAβ over insoluble Aβs (insAβ). Among the designed compounds, CRANAD-102 showed a 68-fold higher affinity for sAβ than for insAβ (7.5 ± 10 nM vs. 505.9 ± 275.9 nM). Moreover, our imaging data indicated that CRANAD-102 was indeed capable of detecting sAβ in vivo using 4 month old APP/PS1 mice, in which sAβ is the predominant species in the brain. In addition, we also demonstrated that CRANAD-102 could be used to monitor the increase in sAβ loading from the ages of 4 months old to 12 months old. We believe that CRANAD-102 can be a useful probe for selectively detecting sAβ species in AD and that our probe designing strategy can be applied to other amyloids and will have tremendous impact on AD drug development and other amyloid research.

  6. Synaptic transmission block by presynaptic injection of oligomeric amyloid beta

    Science.gov (United States)

    Moreno, Herman; Yu, Eunah; Pigino, Gustavo; Hernandez, Alejandro I.; Kim, Natalia; Moreira, Jorge E.; Sugimori, Mutsuyuki; Llinás, Rodolfo R.

    2009-01-01

    Early Alzheimer's disease (AD) pathophysiology is characterized by synaptic changes induced by degradation products of amyloid precursor protein (APP). The exact mechanisms of such modulation are unknown. Here, we report that nanomolar concentrations of intraaxonal oligomeric (o)Aβ42, but not oAβ40 or extracellular oAβ42, acutely inhibited synaptic transmission at the squid giant synapse. Further characterization of this phenotype demonstrated that presynaptic calcium currents were unaffected. However, electron microscopy experiments revealed diminished docked synaptic vesicles in oAβ42-microinjected terminals, without affecting clathrin-coated vesicles. The molecular events of this modulation involved casein kinase 2 and the synaptic vesicle rapid endocytosis pathway. These findings open the possibility of a new therapeutic target aimed at ameliorating synaptic dysfunction in AD. PMID:19304802

  7. Distinct thermodynamic signatures of oligomer generation in the aggregation of the amyloidpeptide

    Science.gov (United States)

    Cohen, Samuel I. A.; Cukalevski, Risto; Michaels, Thomas C. T.; Šarić, Andela; Törnquist, Mattias; Vendruscolo, Michele; Dobson, Christopher M.; Buell, Alexander K.; Knowles, Tuomas P. J.; Linse, Sara

    2018-05-01

    Mapping free-energy landscapes has proved to be a powerful tool for studying reaction mechanisms. Many complex biomolecular assembly processes, however, have remained challenging to access using this approach, including the aggregation of peptides and proteins into amyloid fibrils implicated in a range of disorders. Here, we generalize the strategy used to probe free-energy landscapes in protein folding to determine the activation energies and entropies that characterize each of the molecular steps in the aggregation of the amyloidpeptide (Aβ42), which is associated with Alzheimer's disease. Our results reveal that interactions between monomeric Aβ42 and amyloid fibrils during fibril-dependent secondary nucleation fundamentally reverse the thermodynamic signature of this process relative to primary nucleation, even though both processes generate aggregates from soluble peptides. By mapping the energetic and entropic contributions along the reaction trajectories, we show that the catalytic efficiency of Aβ42 fibril surfaces results from the enthalpic stabilization of adsorbing peptides in conformations amenable to nucleation, resulting in a dramatic lowering of the activation energy for nucleation.

  8. Dynamic PET and SPECT imaging with radioiodinated, amyloid-reactive peptide p5 in mice: a positive role for peptide dehalogenation.

    Science.gov (United States)

    Martin, Emily B; Kennel, Stephen J; Richey, Tina; Wooliver, Craig; Osborne, Dustin; Williams, Angela; Stuckey, Alan; Wall, Jonathan S

    2014-10-01

    Dynamic molecular imaging provides bio-kinetic data that is used to characterize novel radiolabeled tracers for the detection of disease. Amyloidosis is a rare protein misfolding disease that can affect many organs. It is characterized by extracellular deposits composed principally of fibrillar proteins and hypersulfated proteoglycans. We have previously described a peptide, p5, which binds preferentially to amyloid deposits in a murine model of reactive (AA) amyloidosis. We have determined the whole body distribution of amyloid by molecular imaging techniques using radioiodinated p5. The loss of radioiodide from imaging probes due to enzymatic reaction has plagued the use of radioiodinated peptides and antibodies. Therefore, we studied iodine-124-labeled p5 by using dynamic PET imaging of both amyloid-laden and healthy mice to assess the rates of amyloid binding, the relevance of dehalogenation and the fate of the radiolabeled peptide. Rates of blood pool clearance, tissue accumulation and dehalogenation of the peptide were estimated from the images. Comparisons of these properties between the amyloid-laden and healthy mice provided kinetic profiles whose differences may prove to be indicative of the disease state. Additionally, we performed longitudinal SPECT/CT imaging with iodine-125-labeled p5 up to 72h post injection to determine the stability of the radioiodinated peptide when bound to the extracellular amyloid. Our data show that amyloid-associated peptide, in contrast to the unbound peptide, is resistant to dehalogenation resulting in enhanced amyloid-specific imaging. These data further support the utility of this peptide for detecting amyloidosis and monitoring potential therapeutic strategies in patients. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Amyloid-beta binds catalase with high affinity and inhibits hydrogen peroxide breakdown.

    OpenAIRE

    Milton, N G

    1999-01-01

    Amyloid-beta (Abeta) specifically bound purified catalase with high affinity and inhibited catalase breakdown of H(2)O(2). The Abeta-induced catalase inhibition involved formation of the inactive catalase Compound II and was reversible. CatalaseAbeta interactions provide rapid functional assays for the cytotoxic domain of Abeta and suggest a mechanism for some of the observed actions of Abeta plus catalase in vitro.

  10. Brain-predicted age in Down syndrome is associated with beta amyloid deposition and cognitive decline.

    Science.gov (United States)

    Cole, James H; Annus, Tiina; Wilson, Liam R; Remtulla, Ridhaa; Hong, Young T; Fryer, Tim D; Acosta-Cabronero, Julio; Cardenas-Blanco, Arturo; Smith, Robert; Menon, David K; Zaman, Shahid H; Nestor, Peter J; Holland, Anthony J

    2017-08-01

    Individuals with Down syndrome (DS) are more likely to experience earlier onset of multiple facets of physiological aging. This includes brain atrophy, beta amyloid deposition, cognitive decline, and Alzheimer's disease-factors indicative of brain aging. Here, we employed a machine learning approach, using structural neuroimaging data to predict age (i.e., brain-predicted age) in people with DS (N = 46) and typically developing controls (N = 30). Chronological age was then subtracted from brain-predicted age to generate a brain-predicted age difference (brain-PAD) score. DS participants also underwent [ 11 C]-PiB positron emission tomography (PET) scans to index the levels of cerebral beta amyloid deposition, and cognitive assessment. Mean brain-PAD in DS participants' was +2.49 years, significantly greater than controls (p brain-PAD was associated with the presence and the magnitude of PiB-binding and levels of cognitive performance. Our study indicates that DS is associated with premature structural brain aging, and that age-related alterations in brain structure are associated with individual differences in the rate of beta amyloid deposition and cognitive impairment. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  11. Cationization increases brain distribution of an amyloid-beta protofibril selective F(ab')2 fragment

    OpenAIRE

    Syvänen, Stina; Edén, Desireé; Sehlin, Dag

    2017-01-01

    Antibodies and fragments thereof are, because of high selectivity for their targets, considered as potential therapeutics and biomarkers for several neurological disorders. However, due to their large molecular size, antibodies/fragments do not easily penetrate into the brain. The aim of the present study was to improve the brain distribution via adsorptive-mediated transcytosis of an amyloid-beta (A beta) protofibril selective F(ab')2 fragment (F(ab')2-h158). F(ab')2-h158 was cationized to d...

  12. Glutamate carboxypeptidase II does not process amyloid-beta peptide

    Czech Academy of Sciences Publication Activity Database

    Sedlák, František; Šácha, Pavel; Blechová, Miroslava; Březinová, Anna; Šafařík, Martin; Šebestík, Jaroslav; Konvalinka, Jan

    2013-01-01

    Roč. 27, č. 7 (2013), s. 2626-2632 ISSN 0892-6638 R&D Projects: GA ČR GAP304/12/0847 Institutional support: RVO:61388963 Keywords : PSMA * Alzheimer's disease * disaggregation * exopeptidase * substrate specificity * depsipeptide Subject RIV: CE - Biochemistry Impact factor: 5.480, year: 2013

  13. Exploring the early steps of aggregation of amyloid-forming peptide KFFE

    International Nuclear Information System (INIS)

    Wei Guanghong; Mousseau, Normand; Derreumaux, Philippe

    2004-01-01

    It has been shown recently that even a tetrapeptide can form amyloid fibrils sharing all the characteristics of amyloid fibrils built from large proteins. Recent experimental studies also suggest that the toxicity observed in several neurodegenerative diseases, such as Alzheimer's disease and Creutzfeldt-Jakob disease, is not only related to the mature fibrils themselves, but also to the soluble oligomers formed early in the process of fibrillogenesis. This raises the interest in studying the early steps of the aggregation process. Although fibril formation follows the nucleation-condensation process, characterized by the presence of lag phase, the exact pathways remain to be determined. In this study, we used the activation-relaxation technique and a generic energy model to explore the process of self-assembly and the structures of the resulting aggregates of eight KFFE peptides. Our simulations show, starting from different states with a preformed antiparallel dimer, that eight chains can self-assemble to adopt, with various orientations, four possible distant oligomeric well-aligned structures of similar energy. Two of these structures show a double-layer β-sheet organization, in agreement with the structure of amyloid fibrils as observed by x-ray diffraction; another two are mixtures of dimers and trimers. Our results also suggest that octamers are likely to be below the critical size for nucleation of amyloid fibrils for small peptides

  14. Effect of copper (II) ion against elongation behavior of amyloid {beta} fibrils on liposome membranes

    Energy Technology Data Exchange (ETDEWEB)

    Shimanouchi, T.; Onishi, R.; Kitaura, N.; Umakoshi, H.; Kuboi, R. [Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka (Japan)

    2012-01-15

    The fibril growth behavior of amyloid {beta} protein (A{beta}) on cell membranes is relating to the progression of Alzheimer's disease. This growth behavior of A{beta} fibrils is sensitively affected by the metal ions, neurotransmitters, or bioreactive substrate. The inhibitory effect of those materials was quantitatively estimated from the viewpoints of ''crystal growth''. In a bulk aqueous solution, copper (II) ion showed the strong inhibitory effect on the growth of A{beta} fibrils. Meanwhile, the addition of a closed-phospholipid bilayer membrane (liposome) could reduce the above inhibitory effect of copper (II) ion. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Molecular basis and pharmacological implications of Alzheimer amyloid ß-peptide fibril formation,

    OpenAIRE

    Tjernberg, Lars

    1998-01-01

    Alzheimer's disease is a progressive neurodegenerative disease, mostly affectingelderly. The invariable deposition of protease-resistant fibrils of Alzheimer amyloidß-peptide (Aß) in the parenchyma and blood vessels of the brain is a centralevent. The aim of this study was to investigate whether Aß develops proteaseresistance upon polymerization and whether Aß may be generated through non specificproteolysis of a polymerized precursor, to identify Aß-Aß binding and fibrilfor...

  16. Chemokines, macrophage inflammatory protein-2 and stromal cell-derived factor-1{alpha}, suppress amyloid {beta}-induced neurotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Raman, Dayanidhi; Milatovic, Snjezana-Zaja [Department of Cancer Biology, Vanderbilt University, School of Medicine, Nashville, TN 37232 (United States); Milatovic, Dejan [Department of Pediatrics/Pediatric Toxicology, Vanderbilt University, School of Medicine, Nashville, TN 37232 (United States); Splittgerber, Ryan [Department of Cancer Biology, Vanderbilt University, School of Medicine, Nashville, TN 37232 (United States); Fan, Guo-Huang [Department of Neurobiology and Neurotoxicology, Meharry Medical College, Nashville, TN 37221 (United States); Richmond, Ann, E-mail: ann.richmond@vanderbilt.edu [VA Medical Center, Nashville, TN 37232 (United States); Department of Cancer Biology, Vanderbilt University, School of Medicine, Nashville, TN 37232 (United States)

    2011-11-15

    Alzheimer's disease (AD) is characterized by a progressive cognitive decline and accumulation of neurotoxic oligomeric peptides amyloid-{beta} (A{beta}). Although the molecular events are not entirely known, it has become evident that inflammation, environmental and other risk factors may play a causal, disruptive and/or protective role in the development of AD. The present study investigated the ability of the chemokines, macrophage inflammatory protein-2 (MIP-2) and stromal cell-derived factor-1{alpha} (SDF-1{alpha}), the respective ligands for chemokine receptors CXCR2 and CXCR4, to suppress A{beta}-induced neurotoxicity in vitro and in vivo. Pretreatment with MIP-2 or SDF-1{alpha} significantly protected neurons from A{beta}-induced dendritic regression and apoptosis in vitro through activation of Akt, ERK1/2 and maintenance of metalloproteinase ADAM17 especially with SDF-1{alpha}. Intra-cerebroventricular (ICV) injection of A{beta} led to reduction in dendritic length and spine density of pyramidal neurons in the CA1 area of the hippocampus and increased oxidative damage 24 h following the exposure. The A{beta}-induced morphometric changes of neurons and increase in biomarkers of oxidative damage, F{sub 2}-isoprostanes, were significantly inhibited by pretreatment with the chemokines MIP-2 or SDF-1{alpha}. Additionally, MIP-2 or SDF-1{alpha} was able to suppress the aberrant mislocalization of p21-activated kinase (PAK), one of the proteins involved in the maintenance of dendritic spines. Furthermore, MIP-2 also protected neurons against A{beta} neurotoxicity in CXCR2-/- mice, potentially through observed up regulation of CXCR1 mRNA. Understanding the neuroprotective potential of chemokines is crucial in defining the role for their employment during the early stages of neurodegeneration. -- Research highlights: Black-Right-Pointing-Pointer Neuroprotective ability of the chemokines MIP2 and CXCL12 against A{beta} toxicity. Black-Right-Pointing-Pointer MIP

  17. Anti-amyloid treatments in Alzheimer's disease.

    Science.gov (United States)

    Sapra, Mamta; Kim, Kye Y

    2009-06-01

    Alzheimer's disease is one of the most challenging threats to the healthcare system in society. One of the main characteristic of Alzheimer's disease (AD) pathology is formation of amyloid plaques from accumulation of amyloid beta peptide. The therapeutic agents that are currently available for AD including acetylcholinesterase inhibitors (AchEIs) and the N-methyl-D-aspartate (NMDA) antagonist are focused on improving the symptoms and do not revert the progression of the disease. This limitation coupled with the burgeoning increase in the prevalence of AD and resultant impact on healthcare economics calls for more substantial treatments for AD. According to the leading amyloid hypothesis, cleavage of amyloid precursor protein to release amyloid beta peptide is the critical event in pathogenesis of Alzheimer's disease. Recently treatment strategies have been focused on modifying the formation, clearance and accumulation of neurotoxic amyloid beta peptide. This article reviews different therapeutic approaches that have been investigated to target amyloid beta ranging from secretase modulators, antiaggregation agents to amyloid immunotherapy. Authors review the different novel drugs which are in clinical trials.

  18. An infrared spectroscopy approach to follow β-sheet formation in peptide amyloid assemblies

    Science.gov (United States)

    Seo, Jongcheol; Hoffmann, Waldemar; Warnke, Stephan; Huang, Xing; Gewinner, Sandy; Schöllkopf, Wieland; Bowers, Michael T.; von Helden, Gert; Pagel, Kevin

    2017-01-01

    Amyloidogenic peptides and proteins play a crucial role in a variety of neurodegenerative disorders such as Alzheimer's and Parkinson's disease. These proteins undergo a spontaneous transition from a soluble, often partially folded form, into insoluble amyloid fibrils that are rich in β-sheets. Increasing evidence suggests that highly dynamic, polydisperse folding intermediates, which occur during fibril formation, are the toxic species in the amyloid-related diseases. Traditional condensed-phase methods are of limited use for characterizing these states because they typically only provide ensemble averages rather than information about individual oligomers. Here we report the first direct secondary-structure analysis of individual amyloid intermediates using a combination of ion mobility spectrometry-mass spectrometry and gas-phase infrared spectroscopy. Our data reveal that oligomers of the fibril-forming peptide segments VEALYL and YVEALL, which consist of 4-9 peptide strands, can contain a significant amount of β-sheet. In addition, our data show that the more-extended variants of each oligomer generally exhibit increased β-sheet content.

  19. Role of amyloid peptides in vascular dysfunction and platelet dysregulation in Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Ilaria eCanobbio

    2015-03-01

    Full Text Available Alzheimer’s disease (AD is the most common neurodegenerative cause of dementia in the elderly. AD is accompanied by the accumulation of amyloid peptides in the brain parenchyma and in the cerebral vessels. The sporadic form of the AD accounts for about 95% of all cases. It is characterized by a late onset, typically after the age of 65, with a complex and still poorly understood aetiology. Several observations point towards a central role of cerebrovascular dysfunction in the onset of sporadic AD. According to the vascular hypothesis, AD may be initiated by vascular dysfunctions that precede and promote the neurodegenerative process. In accordance to this, AD patients show increased hemorragic or ischemic stroke risks. It is now clear that multiple bidirectional connections exist between AD and cerebrovascular disease, and in this new scenario, the effect of amyloid peptides on vascular cells and blood platelets appear to be central to AD. In this review we analyse the effect of amyloid peptides on vascular function and platelet activation and its contribution to the cerebrovascular pathology associated with AD and the progression of this disease.

  20. SERUM ANALYSIS OF AMYLOID BETA-PROTEIN 1-40 IN HEALTHY SUBJECTS, AUTISTIC CHILDREN AND ALZHEIMER’S PATIENTS

    Directory of Open Access Journals (Sweden)

    Vijendra K. SINGH

    2008-06-01

    Full Text Available Amyloid beta-protein1-40 (AP40 is a low molecu­lar weight peptide produced throughout life during normal cell metabolism and neurodegenerative diseases. Owing to its neurotrophic and neurotoxic effects, the present study was conducted to evalu­ate serum levels of AP40 in healthy subjects, au­tistic children and Alzheimer’s disease patients. Serum AP40 was measured by enzyme-linked im­munosorbent assay (ELISA. AP40 was signifi­cantly higher in normal children compared to nor­mal older controls, in normal children compared to autistic children, and in autistic children compared to Alzheimer’s patients (p value was less than 0.05 for all groups. This finding suggests an age-re­lated decline of serum AP40 in normal aging, as well as in autism and Alzheimer’s disease. This decline may result from abnormal processing of amyloid beta-protein precursor (APP during nor­mal aging and age-related diseases such as autism in children and Alzheimer’s disease in elderly. Possible explanations for this decline may include age-related increased interactions of AP40 with cytoskeletal proteins for brain tissue deposition, increased serine proteases for APP metabolism or hyperimmune reaction (antibodies to AP40 for removal of circulating AP40. To conclude, the AP40 metabolism declines with normal aging and in addition to its role in Alzheimer’s disease this protein might also be a contributing factor in au­tism.

  1. Origin of life. Primordial genetics: Information transfer in a pre-RNA world based on self-replicating beta-sheet amyloid conformers.

    Science.gov (United States)

    Maury, Carl Peter J

    2015-10-07

    The question of the origin of life on Earth can largely be reduced to the question of what was the first molecular replicator system that was able to replicate and evolve under the presumably very harsh conditions on the early Earth. It is unlikely that a functional RNA could have existed under such conditions and it is generally assumed that some other kind of information system preceded the RNA world. Here, I present an informational molecular system that is stable, self-replicative, environmentally responsive, and evolvable under conditions characterized by high temperatures, ultraviolet and cosmic radiation. This postulated pregenetic system is based on the amyloid fold, a functionally unique polypeptide fold characterized by a cross beta-sheet structure in which the beta strands are arranged perpendicular to the fiber axis. Beside an extraordinary structural robustness, the amyloid fold possesses a unique ability to transmit information by a three-dimensional templating mechanism. In amyloidogenesis short peptide monomers are added one by one to the growing end of the fiber. From the same monomeric subunits several structural variants of amyloid may be formed. Then, in a self-replicative mode, a specific amyloid conformer can act as a template and confer its spatially encoded information to daughter molecular entities in a repetitive way. In this process, the specific conformational information, the spatially changed organization, is transmitted; the coding element is the steric zipper structure, and recognition occurs by amino acid side chain complementarity. The amyloid information system fulfills several basic requirements of a primordial evolvable replicator system: (i) it is stable under the presumed primitive Earth conditions, (ii) the monomeric building blocks of the informational polymer can be formed from available prebiotic compounds, (iii) the system is self-assembling and self-replicative and (iv) it is adaptive to changes in the environment and

  2. Caspase activation increases beta-amyloid generation independently of caspase cleavage of the beta-amyloid precursor protein (APP).

    Science.gov (United States)

    Tesco, Giuseppina; Koh, Young Ho; Tanzi, Rudolph E

    2003-11-14

    The amyloid precursor protein (APP) undergoes "alternative" proteolysis mediated by caspases. Three major caspase recognition sites have been identified in the APP, i.e. one at the C terminus (Asp720) and two at the N terminus (Asp197 and Asp219). Caspase cleavage at Asp720 has been suggested as leading to increased production of Abeta. Thus, we set out to determine which putative caspase sites in APP, if any, are cleaved in Chinese hamster ovary cell lines concurrently with the increased Abeta production that occurs during apoptosis. We found that cleavage at Asp720 occurred concurrently with caspase 3 activation and the increased production of total secreted Abeta and Abeta1-42 in association with staurosporine- and etoposide-induced apoptosis. To investigate the contribution of caspase cleavage of APP to Abeta generation, we expressed an APP mutant truncated at Asp720 that mimics APP caspase cleavage at the C-terminal site. This did not increase Abeta generation but, in contrast, dramatically decreased Abeta production in Chinese hamster ovary cells. Furthermore, the ablation of caspase-dependent cleavage at Asp720, Asp197, and Asp219 (by site-directed mutagenesis) did not prevent enhanced Abeta production following etoposide-induced apoptosis. These findings indicate that the enhanced Abeta generation associated with apoptosis does not require cleavage of APP at its C-terminal (Asp720) and/or N-terminal caspase sites.

  3. Amyloid-beta immunotherapy: the hope for Alzheimer disease?

    Science.gov (United States)

    Barrera-Ocampo, Alvaro; Lopera, Francisco

    2016-12-30

    Alzheimer disease (AD) is the most prevalent form of dementia of adult-onset, characterized by progressive impairment in cognition and memory. There is no cure for the disease and the current treatments are only symptomatic. Drug discovery is an expensive and time-consuming process; in the last decade no new drugs have been found for AD despite the efforts of the scientific community and pharmaceutical companies. The Aβ immunotherapy is one of the most promising approaches to modify the course of AD. This therapeutic strategy uses synthetic peptides or monoclonal antibodies (mAb) to decrease the Aβ load in the brain and slow the progression of the disease. Therefore, this article will discuss the main aspects of AD neuropathogenesis, the classical pharmacologic treatment, as well as the active and passive immunization describing drug prototypes evaluated in different clinical trials.

  4. Protective effects of some medicinal plants from Lamiaceae family against beta-amyloid induced toxicity in PC12 cell

    Directory of Open Access Journals (Sweden)

    Balali P

    2012-10-01

    Full Text Available Background: Excessive accumulation of beta-amyliod peptide (Aβ, the major component of senile plaques in Alzheimer's disease (AD, causes neuronal cell death through induction of oxidative stress. Therefore, antioxidants may be of use in the treatment of AD. The medicinal plants from the Lamiaceae family have been widely used in Iranian traditional medicine. These plants contain compounds with antioxidant activity and some species in this family have been reported to have neuroprotective properties. In the present study, methanolic extract of seven plants from salvia and satureja species were evaluated for their protective effects against beta-amyloid induced neurotoxicity.Methods: Aerial parts of the plants were extracted with ethyl acetate and methanol, respectively, by percolation at room temperature and subsequently, methanolic extracts of the plants were prepared. PC12 cells were incubated with different concentrations of the extracts in culture medium 1h prior to incubation with Aβ. Cell toxicity was assessed 24h after addition of Aβ by MTT assay.Results: Satureja bachtiarica, Salvia officinalis and Salvia macrosiphon methanolic extracts exhibited high protective effects against Aβ induced toxicity (P<0.001. Protective effects of Satureja bachtiarica and Salvia officinalis were dose-dependent.Conclusion: The main constituents of these extracts are polyphenolic and flavonoid compounds such as rosmarinic acid, naringenin, apigenin and luteolin which have antioxidant properties and may have a role in neuroprotection. Based on neuroprotective effect of these plants against Aβ induced toxicity, we recommend greater attention to their use in the treatment of Alzheimer disease.

  5. Levels of alpha- and beta-secretase cleaved amyloid precursor protein in the cerebrospinal fluid of Alzheimer's disease patients

    DEFF Research Database (Denmark)

    Sennvik, K; Fastbom, J; Blomberg, M

    2000-01-01

    Alternative cleavage of the amyloid precursor protein (APP) results in generation and secretion of both soluble APP (sAPP) and beta-amyloid (Abeta). Abeta is the main component of the amyloid depositions in the brains of Alzheimer's disease (AD) patients. Using Western blotting, we compared...... the levels of alpha-secretase cleaved sAPP, beta-secretase cleaved sAPP and total sAPP, in cerebrospinal fluid (CSF) from 13 sporadic AD patients and 13 healthy controls. Our findings show significant amounts of beta-secretase cleaved sAPP in CSF. There was no statistically significant difference...... in the levels of beta-secretase cleaved sAPP between AD patients and controls. The levels of alpha-secretase cleaved sAPP and total sAPP were, however, found to be significantly lower in the AD patients than in the controls....

  6. Interleukin-3 prevents neuronal death induced by amyloid peptide

    Directory of Open Access Journals (Sweden)

    Otth Carola

    2007-10-01

    Full Text Available Abstract Background Interleukin-3 (IL-3 is an important glycoprotein involved in regulating biological responses such as cell proliferation, survival and differentiation. Its effects are mediated via interaction with cell surface receptors. Several studies have demonstrated the expression of IL-3 in neurons and astrocytes of the hippocampus and cortices in normal mouse brain, suggesting a physiological role of IL-3 in the central nervous system. Although there is evidence indicating that IL-3 is expressed in some neuronal populations, its physiological role in these cells is poorly known. Results In this study, we demonstrated the expression of IL-3 receptor in cortical neurons, and analyzed its influence on amyloid β (Aβ-treated cells. In these cells, IL-3 can activate at least three classical signalling pathways, Jak/STAT, Ras/MAP kinase and the PI 3-kinase. Viability assays indicated that IL-3 might play a neuroprotective role in cells treated with Aβ fibrils. It is of interest to note that our results suggest that cell survival induced by IL-3 required PI 3-kinase and Jak/STAT pathway activation, but not MAP kinase. In addition, IL-3 induced an increase of the anti-apoptotic protein Bcl-2. Conclusion Altogether these data strongly suggest that IL-3 neuroprotects neuronal cells against neurodegenerative agents like Aβ.

  7. Amyloid fibril formation of peptides derived from the C-terminus of CETP modulated by lipids

    Energy Technology Data Exchange (ETDEWEB)

    García-González, Victor [Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 México, DF (Mexico); Mas-Oliva, Jaime, E-mail: jmas@ifc.unam.mx [Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 México, DF (Mexico); División de Investigación, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510 México, DF (Mexico)

    2013-04-26

    Highlights: •The secondary structure of a C-terminal peptide derived from CETP was studied. •Lipids modulate secondary structure changes of a C-terminal peptide derived from CETP. •Lysophosphatidic acid maintains a functional α-helix and prevents fibril formation. •Transfer of lipids by CETP is related to the presence of an α-helix at its C-end. -- Abstract: Cholesteryl-ester transfer protein (CETP) is a plasmatic protein involved in neutral lipid transfer between lipoproteins. Focusing on the last 12 C-terminus residues we have previously shown that mutation D{sub 470}N promotes a conformational change towards a β-secondary structure. In turn, this modification leads to the formation of oligomers and fibrillar structures, which cause cytotoxic effects similar to the ones provoked by amyloid peptides. In this study, we evaluated the role of specific lipid arrangements on the structure of peptide helix-Z (D{sub 470}N) through the use of thioflavin T fluorescence, peptide bond absorbance, circular dichroism and electron microscopy. The results indicate that the use of micelles formed with lysophosphatidylcholine and lysophosphatidic acid (LPA) under neutral pH induce a conformational transition of peptide helix-Z containing a β-sheet conformation to a native α-helix structure, therefore avoiding the formation of amyloid fibrils. In contrast, incubation with phosphatidic acid does not change the profile for the β-sheet conformation. When the electrostatic charge at the surface of micelles or vesicles is regulated through the use of lipids such as phospholipid and LPA, minimal changes and the presence of β-structures were recorded. Mixtures with a positive net charge diminished the percentage of β-structure and the amount of amyloid fibrils. Our results suggest that the degree of solvation determined by the presence of a free hydroxyl group on lipids such as LPA is a key condition that can modulate the secondary structure and the consequent formation of

  8. Amyloid fibril formation of peptides derived from the C-terminus of CETP modulated by lipids

    International Nuclear Information System (INIS)

    García-González, Victor; Mas-Oliva, Jaime

    2013-01-01

    Highlights: •The secondary structure of a C-terminal peptide derived from CETP was studied. •Lipids modulate secondary structure changes of a C-terminal peptide derived from CETP. •Lysophosphatidic acid maintains a functional α-helix and prevents fibril formation. •Transfer of lipids by CETP is related to the presence of an α-helix at its C-end. -- Abstract: Cholesteryl-ester transfer protein (CETP) is a plasmatic protein involved in neutral lipid transfer between lipoproteins. Focusing on the last 12 C-terminus residues we have previously shown that mutation D 470 N promotes a conformational change towards a β-secondary structure. In turn, this modification leads to the formation of oligomers and fibrillar structures, which cause cytotoxic effects similar to the ones provoked by amyloid peptides. In this study, we evaluated the role of specific lipid arrangements on the structure of peptide helix-Z (D 470 N) through the use of thioflavin T fluorescence, peptide bond absorbance, circular dichroism and electron microscopy. The results indicate that the use of micelles formed with lysophosphatidylcholine and lysophosphatidic acid (LPA) under neutral pH induce a conformational transition of peptide helix-Z containing a β-sheet conformation to a native α-helix structure, therefore avoiding the formation of amyloid fibrils. In contrast, incubation with phosphatidic acid does not change the profile for the β-sheet conformation. When the electrostatic charge at the surface of micelles or vesicles is regulated through the use of lipids such as phospholipid and LPA, minimal changes and the presence of β-structures were recorded. Mixtures with a positive net charge diminished the percentage of β-structure and the amount of amyloid fibrils. Our results suggest that the degree of solvation determined by the presence of a free hydroxyl group on lipids such as LPA is a key condition that can modulate the secondary structure and the consequent formation of amyloid

  9. Adherence to the Mediterranean Diet Is not Related to Beta-Amyloid Deposition: Data from the Women's Healthy Ageing Project.

    Science.gov (United States)

    Hill, E; Szoeke, C; Dennerstein, L; Campbell, S; Clifton, P

    2018-01-01

    Research has indicated the neuroprotective potential of the Mediterranean diet. Adherence to the Mediterranean diet has shown preventative potential for Alzheimer's disease incidence and prevalence, yet few studies have investigated the impact of Mediterranean diet adherence on the hallmark protein; beta-amyloid. To investigate the association between Mediterranean diet adherence and beta-amyloid deposition in a cohort of healthy older Australian women. This study was a cross-sectional investigation of participants from the longitudinal, epidemiologically sourced Women's Healthy Ageing Project which is a follow-up of the Melbourne Women's Midlife Health Project. Assessments were conducted at the Centre for Medical Research, Royal Melbourne Hospital in Melbourne, Australia. F-18 Florbetaben positron emission tomography scanning was conducted at the Austin Centre for PET in Victoria, Australia. One hundred and eleven Women's Healthy Ageing Project participants were included in the study. Mediterranean diet adherence scores for all participants were calculated from the administration of a validated food frequency questionnaire constructed by the Cancer Council of Victoria. Beta-amyloid deposition was measured using positron emission tomography standardised uptake value ratios. Gamma regression analysis displayed no association between Mediterranean diet adherence and beta-amyloid deposition. This result was consistent across APOE-ε4 +/- cohorts and with the inclusion of covariates such as age, education, body mass index and cognition. This study found no association between adherence to the Mediterranean diet and beta-amyloid deposition in a cohort of healthy Australian women.

  10. Molecular architecture of human prion protein amyloid: a parallel, in-register beta-structure.

    Science.gov (United States)

    Cobb, Nathan J; Sönnichsen, Frank D; McHaourab, Hassane; Surewicz, Witold K

    2007-11-27

    Transmissible spongiform encephalopathies (TSEs) represent a group of fatal neurodegenerative diseases that are associated with conformational conversion of the normally monomeric and alpha-helical prion protein, PrP(C), to the beta-sheet-rich PrP(Sc). This latter conformer is believed to constitute the main component of the infectious TSE agent. In contrast to high-resolution data for the PrP(C) monomer, structures of the pathogenic PrP(Sc) or synthetic PrP(Sc)-like aggregates remain elusive. Here we have used site-directed spin labeling and EPR spectroscopy to probe the molecular architecture of the recombinant PrP amyloid, a misfolded form recently reported to induce transmissible disease in mice overexpressing an N-terminally truncated form of PrP(C). Our data show that, in contrast to earlier, largely theoretical models, the con formational conversion of PrP(C) involves major refolding of the C-terminal alpha-helical region. The core of the amyloid maps to C-terminal residues from approximately 160-220, and these residues form single-molecule layers that stack on top of one another with parallel, in-register alignment of beta-strands. This structural insight has important implications for understanding the molecular basis of prion propagation, as well as hereditary prion diseases, most of which are associated with point mutations in the region found to undergo a refolding to beta-structure.

  11. Hydrodynamic effects on β-amyloid (16-22) peptide aggregation

    Energy Technology Data Exchange (ETDEWEB)

    Chiricotto, Mara; Sterpone, Fabio, E-mail: fabio.sterpone@ibpc.fr [Laboratoire de Biochimie Théorique, IBPC, CNRS UPR9080, University Paris Diderot, Sorbonne Paris Cité, 13 rue Pierre et Marie Curie, 75005 Paris (France); Melchionna, Simone [CNR-ISC, Institute for Complex System, Consiglio Nazionale delle Ricerche, Rome (Italy); Derreumaux, Philippe [Laboratoire de Biochimie Théorique, IBPC, CNRS UPR9080, University Paris Diderot, Sorbonne Paris Cité, 13 rue Pierre et Marie Curie, 75005 Paris (France); IUF, Institut Universitaire de France, Boulevard Saint Michel, 75005 Paris (France)

    2016-07-21

    Computer simulations based on simplified representations are routinely used to explore the early steps of amyloid aggregation. However, when protein models with implicit solvent are employed, these simulations miss the effect of solvent induced correlations on the aggregation kinetics and lifetimes of metastable states. In this work, we apply the multi-scale Lattice Boltzmann Molecular Dynamics technique (LBMD) to investigate the initial aggregation phases of the amyloid Aβ{sub 16−22} peptide. LBMD includes naturally hydrodynamic interactions (HIs) via a kinetic on-lattice representation of the fluid kinetics. The peptides are represented by the flexible OPEP coarse-grained force field. First, we have tuned the essential parameters that control the coupling between the molecular and fluid evolutions in order to reproduce the experimental diffusivity of elementary species. The method is then deployed to investigate the effect of HIs on the aggregation of 100 and 1000 Aβ{sub 16−22} peptides. We show that HIs clearly impact the aggregation process and the fluctuations of the oligomer sizes by favouring the fusion and exchange dynamics of oligomers between aggregates. HIs also guide the growth of the leading largest cluster. For the 100 Aβ{sub 16−22} peptide system, the simulation of ∼300 ns allowed us to observe the transition from ellipsoidal assemblies to an elongated and slightly twisted aggregate involving almost the totality of the peptides. For the 1000 Aβ{sub 16−22} peptides, a system of unprecedented size at quasi-atomistic resolution, we were able to explore a branched disordered fibril-like structure that has never been described by other computer simulations, but has been observed experimentally.

  12. Fibrils from designed non-amyloid-related synthetic peptides induce AA-amyloidosis during inflammation in an animal model.

    Directory of Open Access Journals (Sweden)

    Per Westermark

    Full Text Available BACKGROUND: Mouse AA-amyloidosis is a transmissible disease by a prion-like mechanism where amyloid fibrils act by seeding. Synthetic peptides with no amyloid relationship can assemble into amyloid-like fibrils and these may have seeding capacity for amyloid proteins. PRINCIPAL FINDINGS: Several synthetic peptides, designed for nanotechnology, have been examined for their ability to produce fibrils with Congo red affinity and concomitant green birefringence, affinity for thioflavin S and to accelerate AA-amyloidosis in mice. It is shown that some amphiphilic fibril-forming peptides not only produced Congo red birefringence and showed affinity for thioflavin S, but they also shortened the lag phase for systemic AA-amyloidosis in mice when they were given intravenously at the time of inflammatory induction with silver nitride. Peptides, not forming amyloid-like fibrils, did not have such properties. CONCLUSIONS: These observations should caution researchers and those who work with synthetic peptides and their derivatives to be aware of the potential health concerns.

  13. Protein kinase C involvement in the acetylcholine release reduction induced by amyloid-beta(25-35) aggregates on neuromuscular synapses.

    Science.gov (United States)

    Tomàs, Marta; Garcia, Neus; Santafé, Manuel M; Lanuza, Maria; Tomàs, Josep

    2009-01-01

    Using intracellular recording of the diaphragm muscle of adult rats, we have investigated the short-term functional effects of amyloid-beta (Abeta(25-35) peptide aggregates on the modulation of acetylcholine (ACh) release and the involvement of protein kinase C (PKC). The non-aggregated form of this peptide does not change the evoked and spontaneous transmitter release parameters on the neuromuscular synapse. However, the aggregated form of Abeta(25-35) acutely interferes with evoked quantal ACh release (approximately 40% reduction) when synaptic activity in the ex vivo neuromuscular preparation is maintained by low frequency (1 Hz) electrical stimulation. This effect is partially dependent on the activity of PKC that may have a permissive action. The end result of Abeta(25-35) is in opposition to the PKC-dependent maintenance effect on ACh release manifested in active synapses.

  14. Indexing amyloid peptide diffraction from serial femtosecond crystallography: new algorithms for sparse patterns

    Energy Technology Data Exchange (ETDEWEB)

    Brewster, Aaron S. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Sawaya, Michael R. [University of California, Los Angeles, CA 90095-1570 (United States); University of California, Los Angeles, CA 90095-1570 (United States); University of California, Los Angeles, CA 90095-1570 (United States); Rodriguez, Jose [University of California, Los Angeles, CA 90095-1570 (United States); University of California, Los Angeles, CA 90095-1570 (United States); Hattne, Johan; Echols, Nathaniel [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); McFarlane, Heather T. [University of California, Los Angeles, CA 90095-1570 (United States); University of California, Los Angeles, CA 90095-1570 (United States); Cascio, Duilio [University of California, Los Angeles, CA 90095-1570 (United States); University of California, Los Angeles, CA 90095-1570 (United States); University of California, Los Angeles, CA 90095-1570 (United States); Adams, Paul D. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); University of California, Berkeley, CA 94720 (United States); Eisenberg, David S. [University of California, Los Angeles, CA 90095-1570 (United States); University of California, Los Angeles, CA 90095-1570 (United States); University of California, Los Angeles, CA 90095-1570 (United States); Sauter, Nicholas K., E-mail: nksauter@lbl.gov [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2015-02-01

    Special methods are required to interpret sparse diffraction patterns collected from peptide crystals at X-ray free-electron lasers. Bragg spots can be indexed from composite-image powder rings, with crystal orientations then deduced from a very limited number of spot positions. Still diffraction patterns from peptide nanocrystals with small unit cells are challenging to index using conventional methods owing to the limited number of spots and the lack of crystal orientation information for individual images. New indexing algorithms have been developed as part of the Computational Crystallography Toolbox (cctbx) to overcome these challenges. Accurate unit-cell information derived from an aggregate data set from thousands of diffraction patterns can be used to determine a crystal orientation matrix for individual images with as few as five reflections. These algorithms are potentially applicable not only to amyloid peptides but also to any set of diffraction patterns with sparse properties, such as low-resolution virus structures or high-throughput screening of still images captured by raster-scanning at synchrotron sources. As a proof of concept for this technique, successful integration of X-ray free-electron laser (XFEL) data to 2.5 Å resolution for the amyloid segment GNNQQNY from the Sup35 yeast prion is presented.

  15. Benchmarking of copper(II) LFMM parameters for studying amyloidpeptides.

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    Mutter, Shaun T; Deeth, Robert J; Turner, Matthew; Platts, James A

    2018-04-01

    Ligand field molecular mechanics (LFMM) parameters have been benchmarked for copper (II) bound to the amyloid-β 1-16 peptide fragment. Several density functional theory (DFT) optimised small test models, representative of different possible copper coordination modes, have been used to test the accuracy of the LFMM copper bond lengths and angles, resulting in errors typically less than 0.1 Å and 5°. Ligand field molecular dynamics (LFMD) simulations have been carried out on the copper bound amyloid-β 1-16 peptide and snapshots extracted from the subsequent trajectory. Snapshots have been optimised using DFT and the semi-empirical PM7 method resulting in good agreement against the LFMM calculated geometry. Analysis of substructures within snapshots shows that the larger contribution of geometrical difference, as measured by RMSD, lies within the peptide backbone, arising from differences in DFT and AMBER, and the copper coordination sphere is reproduced well by LFMM. PM7 performs excellently against LFMM with an average RMSD of 0.2 Å over 21 tested snapshots. Further analysis of the LFMD trajectory shows that copper bond lengths and angles have only small deviations from average values, with the exception of a carbonyl moiety from the N-terminus, which can act as a weakly bound fifth ligand.

  16. In vitro fibrillization of Alzheimer’s amyloidpeptide (1-42)

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    Tiiman, Ann [Department of Gene Technology, Tallinn University of Technology, Tallinn 12618 (Estonia); Department of Biochemistry and Biophysics, Arrhenius Laboratories, Stockholm University, Stockholm, 106 91 (Sweden); Krishtal, Jekaterina; Palumaa, Peep; Tõugu, Vello, E-mail: vello.tougu@ttu.ee [Department of Gene Technology, Tallinn University of Technology, Tallinn 12618 (Estonia)

    2015-09-15

    The amyloid deposition in the form of extracellular fibrillar aggregates of amyloid-β (Aβ) peptide is a critical pathological event in Alzheimer’s disease. Here, we report a systematic investigation of the effects of environmental factors on the kinetics of Aβ fibrillization in vitro. The effects of Aβ42 peptide concentration, temperature, pH, added solvents and the ratio of Aβ40 and Aβ42 on the peptide fibrillization under agitated conditions was studied. The analysis show that the rate of fibril growth by monomer addition is not limited by diffusion but by rearrangement in the monomer structure, which is enhanced by low concentrations of fluorinated alcohols and characterized by the activation energy of 12 kcal/mol. Fibrillization rate decreases at pH values below 7.0 where simultaneous protonation of His 13 and 14 inhibits fibril formation. The lag period for Aβ42 was only twofold shorter and the fibril growth rate twofold faster than those of Aβ40. Lag period was shortened and the fibrillization rate was increased only at 90% content of Aβ42.

  17. Methyl Salicylate Lactoside Protects Neurons Ameliorating Cognitive Disorder Through Inhibiting Amyloid Beta-Induced Neuroinflammatory Response in Alzheimer's Disease.

    Science.gov (United States)

    Li, Jinze; Ma, Xiaowei; Wang, Yu; Chen, Chengjuan; Hu, Min; Wang, Linlin; Fu, Junmin; Shi, Gaona; Zhang, Dongming; Zhang, Tiantai

    2018-01-01

    Neuroinflammatory reactions mediated by microglia and astrocytes have been shown to play a key role in early progression of Alzheimer's disease (AD). Increased evidences have demonstrated that neurons exacerbate local inflammatory reactions by producing inflammatory mediators and act as an important participant in the pathogenesis of AD. Methyl salicylate lactoside (MSL) is an isolated natural product that is part of a class of novel non-steroidal anti-inflammatory drugs (NSAID). In our previous studies, we demonstrated that MSL exhibited therapeutic effects on arthritis-induced mice and suppressed the activation of glial cells. In the current study, we investigated the effects of MSL on cognitive function and neuronal protection induced by amyloid-beta peptides (Aβ) and explored potential underlying mechanisms involved. Amyloid precursor protein (APP) and presenilin 1 (PS1) double transgenic mice were used to evaluate the effects of MSL through behavioral testing and neuronal degenerative changes. In addition, copper-injured APP Swedish mutation overexpressing SH-SY5Y cells were used to determine the transduction of cyclooxygenase (COX) and mitogen-activated protein kinase (MAPK) pathways. Our results indicated that at an early stage, MSL treatment ameliorated cognitive impairment and neurodegeneration in APP/PS1 mice. Moreover, in an in vitro AD model, MSL treatment protected injured cells by increasing cell viability, improving mitochondrial dysfunction, and decreasing oxidative damage. In addition, MSL inhibited the phosphorylated level of c-Jun N-terminal kinase (JNK) and p38 MAPK, and suppressed the expression of COX-1/2. As a novel NSAIDs and used for the treatment in early stage of AD, MSL clearly demonstrated cognitive preservation by protecting neurons via a pleiotropic anti-inflammatory effect in the context of AD-associated deficits. Therefore, early treatment of anti-inflammatory therapy may be an effective strategy for treating AD.

  18. Isobaric Quantification of Cerebrospinal Fluid AmyloidPeptides in Alzheimer's Disease: C-Terminal Truncation Relates to Early Measures of Neurodegeneration.

    Science.gov (United States)

    Rogeberg, Magnus; Almdahl, Ina Selseth; Wettergreen, Marianne; Nilsson, Lars N G; Fladby, Tormod

    2015-11-06

    The amyloid beta (Aβ) peptide is the main constituent of the plaques characteristic of Alzheimer's disease (AD). Measurement of Aβ1-42 in cerebrospinal fluid (CSF) is a valuable marker in AD research, where low levels indicate AD. Although the use of immunoassays measuring Aβ1-38 and Aβ1-40 in addition to Aβ1-42 has increased, quantitative assays of other Aβ peptides remain rarely explored. We recently discovered novel Aβ peptides in CSF using antibodies recognizing the Aβ mid-domain region. Here we have developed a method using both Aβ N-terminal and mid-domain antibodies for immunoprecipitation in combination with isobaric labeling and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for relative quantification of endogenous Aβ peptides in CSF. The developed method was used in a pilot study to produce Aβ peptide profiles from 38 CSF samples. Statistical comparison between CSF samples from 19 AD patients and 19 cognitively healthy controls revealed no significant differences at group level. A significant correlation was found between several larger C-terminally truncated Aβ peptides and protein biomarkers for neuronal damage, particularly prominent in the control group. Comparison of the isobaric quantification with immunoassays measuring Aβ1-38 or Aβ1-40 showed good correlation (r(2) = 0.84 and 0.85, respectively) between the two analysis methods. The developed method could be used to assess disease-modifying therapies directed at Aβ production or degradation.

  19. Impairment of context memory by β-amyloid peptide in terrestrial snail

    Directory of Open Access Journals (Sweden)

    2008-09-01

    Full Text Available We examined influence of the β-amyloid peptide (25-35 neurotoxic fragment (βAP on Helix lucorum food-aversion learning. Testing with aversively conditioned carrot showed that 2, 5, and 14 days after training the βAP-injected group responded in a significantly larger number of cases and with a significantly smaller latency than the sham-injected control group. The results demonstrate that the amyloid peptide partially impairs the learning process. In an attempt to specify what component of memory is impaired we compared responses in a context in which the snails were aversively trained, and in a neutral context. It was found that the sham-injected learned snails significantly less frequently took the aversively conditioned food in the context in which the snails were shocked, while the βAP-injected snails remembered the aversive context 2 days after associative training, but were not able to distinguish two contexts 5, and 14 days after training. In a separate series of experiments a specific context was associated with electric shock, and changes in general responsiveness were tested in two contexts several days later. It was found that the βAP-injected snails significantly increased withdrawal responses in all tested contexts, while the sham-injected control animals selectively increased responsiveness only in the context in which they were reinforced with electric shocks. These results demonstrate that the β-amyloid peptide (25-35 interferes with the learning process, and may play a significant role in behavioral plasticity and memory by selectively impairing only one

  20. Novel Detox Gel Depot sequesters β-Amyloid Peptides in a mouse model of Alzheimer's Disease.

    Science.gov (United States)

    Sundaram, Ranjini K; Kasinathan, Chinnaswamy; Stein, Stanley; Sundaram, Pazhani

    2012-06-01

    Alzheimer's Disease (AD), a debilitating neurodegenerative disease is caused by aggregation and accumulation of a 39-43 amino acid peptide (amyloid β or Aβ) in brain parenchyma and cerebrovasculature. The rational approach would be to use drugs that interfere with Aβ-Aβ interaction and disrupt polymerization. Peptide ligands capable of binding to the KLVFF (amino acids 16-20) region in the Aβ molecule have been investigated as possible drug candidates. Retro-inverso (RI) peptide of this pentapeptide, ffvlk, has been shown to bind artificial fibrils made from Aβ with moderate affinity. We hypothesized that a 'detox gel', which is synthesized by covalently linking a tetrameric version of RI peptide ffvlk to poly (ethylene glycol) polymer chains will act like a 'sink' to capture Aβ peptides from the surrounding environment. We previously demonstrated that this hypothesis works in an in vitro system. The present study extended this hypothesis to an in vivo mouse model of Alzheimer's Disease and determined the therapeutic effect of our detox gel. We injected detox gel subcutaneously to AD model mice and analyzed brain levels of Aβ-42 and improvement in memory parameters. The results showed a reduction of brain amyloid burden in detox gel treated mice. Memory parameters in the treated mice improved. No undesirable immune response was observed. The data strongly suggest that our detox gel can be used as an effective therapy to deplete brain Aβ levels. Considering recent abandonment of failed antibody based therapies, our detox gel appears to have the advantage of being a non-immune based therapy.

  1. The influence of pathological mutations and proline substitutions in TDP-43 glycine-rich peptides on its amyloid properties and cellular toxicity.

    Directory of Open Access Journals (Sweden)

    Chia-Sui Sun

    Full Text Available TAR DNA-binding protein (TDP-43 was identified as the major ubiquitinated component deposited in the inclusion bodies in amyotrophic lateral sclerosis (ALS and frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U in 2006. Later on, numerous ALS-related mutations were found in either the glycine or glutamine/asparagine-rich region on the TDP-43 C-terminus, which hinted on the importance of mutations on the disease pathogenesis. However, how the structural conversion was influenced by the mutations and the biological significance of these peptides remains unclear. In this work, various peptides bearing pathogenic or de novo designed mutations were synthesized and displayed their ability to form twisted amyloid fibers, cause liposome leakage, and mediate cellular toxicity as confirmed by transmission electron microscopy (TEM, circular dichroism (CD, Thioflavin T (ThT assay, Raman spectroscopy, calcein leakage assay, and cell viability assay. We have also shown that replacing glycines with prolines, known to obstruct β-sheet formation, at the different positions in these peptides may influence the amyloidogenesis process and neurotoxicity. In these cases, GGG308PPP mutant was not able to form beta-amyloid, cause liposome leakage, nor jeopardized cell survival, which hinted on the importance of the glycines (308-310 during amyloidogenesis.

  2. High frequency NcoI RFLP detected in the Alzheimer amyloid peptide gene

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y; Dobkin, C; Devine-Gage, E; Ramakrishna, N; Brown, W T; Wisniewski, H M; Robakis, N K

    1988-02-25

    Probe pAMB2.3 contains a 778bp cDNA fragment encoding the amyloid polypeptide of Alzheimer disease and Down Syndrome (beta protein) inserted into pUC18. The probe was sublocalized to chromosome 21q21. NcoI identifies a two allele polymorphism of a band at either 15 kb or 8.5 kb. Autosomal codominant inheritance was shown in five informative families. Two non polymorphic bands, 7.0kb and 6.0kb, are seen only occasionally. Their presence seems to depend on the particular DNA preparation.

  3. Spatial distribution of diffuse, primitive, and classic amyloid-beta deposits and blood vessels in the upper laminae of the frontal cortex in Alzheimer disease.

    Science.gov (United States)

    Armstrong, R A; Cairns, N J; Lantos, P L

    1998-12-01

    The spatial distribution of the diffuse, primitive, and classic amyloid-beta deposits was studied in the upper laminae of the superior frontal gyrus in cases of sporadic Alzheimer disease (AD). Amyloid-beta-stained tissue was counterstained with collagen IV to determine whether the spatial distribution of the amyloid-beta deposits along the cortex was related to blood vessels. In all patients, amyloid-beta deposits and blood vessels were aggregated into distinct clusters and in many patients, the clusters were distributed with a regular periodicity along the cortex. The clusters of diffuse and primitive deposits did not coincide with the clusters of blood vessels in most patients. However, the clusters of classic amyloid-beta deposits coincided with those of the large diameter (>10 microm) blood vessels in all patients and with clusters of small-diameter (upper cortical laminae.

  4. Synthesis, Molecular Modelling and Biological Evaluation of Novel Heterodimeric, Multiple Ligands Targeting Cholinesterases and Amyloid Beta

    Directory of Open Access Journals (Sweden)

    Michalina Hebda

    2016-03-01

    Full Text Available Cholinesterases and amyloid beta are one of the major biological targets in the search for a new and efficacious treatment of Alzheimer’s disease. The study describes synthesis and pharmacological evaluation of new compounds designed as dual binding site acetylcholinesterase inhibitors. Among the synthesized compounds, two deserve special attention—compounds 42 and 13. The former is a saccharin derivative and the most potent and selective acetylcholinesterase inhibitor (EeAChE IC50 = 70 nM. Isoindoline-1,3-dione derivative 13 displays balanced inhibitory potency against acetyl- and butyrylcholinesterase (BuChE (EeAChE IC50 = 0.76 μM, EqBuChE IC50 = 0.618 μM, and it inhibits amyloid beta aggregation (35.8% at 10 μM. Kinetic studies show that the developed compounds act as mixed or non-competitive acetylcholinesterase inhibitors. According to molecular modelling studies, they are able to interact with both catalytic and peripheral active sites of the acetylcholinesterase. Their ability to cross the blood-brain barrier (BBB was confirmed in vitro in the parallel artificial membrane permeability BBB assay. These compounds can be used as a solid starting point for further development of novel multifunctional ligands as potential anti-Alzheimer’s agents.

  5. Multiscale Molecular Dynamics Simulations of Beta-Amyloid Interactions with Neurons

    Science.gov (United States)

    Qiu, Liming; Vaughn, Mark; Cheng, Kelvin

    2012-10-01

    Early events of human beta-amyloid protein interactions with cholesterol-containing membranes are critical to understanding the pathogenesis of Alzheimer's disease (AD) and to exploring new therapeutic interventions of AD. Atomistic molecular dynamics (AMD) simulations have been extensively used to study the protein-lipid interaction at high atomic resolutions. However, traditional MD simulations are not efficient in sampling the phase space of complex lipid/protein systems with rugged free energy landscapes. Meanwhile, coarse-grained MD (CGD) simulations are efficient in the phase space sampling but suffered from low spatial resolutions and from the fact that the energy landscapes are not identical to those of the AMD. Here, a multiscale approach was employed to simulate the protein-lipid interactions of beta-amyloid upon its release from proteolysis residing in the neuronal membranes. We utilized a forward (AMD to CGD) and reverse (CGD-AMD) strategy to explore new transmembrane and surface protein configuration and evaluate the stabilization mechanisms by measuring the residue-specific protein-lipid or protein conformations. The detailed molecular interactions revealed in this multiscale MD approach will provide new insights into understanding the early molecular events leading to the pathogenesis of AD.

  6. PPARgamma agonist curcumin reduces the amyloid-beta-stimulated inflammatory responses in primary astrocytes.

    Science.gov (United States)

    Wang, Hong-Mei; Zhao, Yan-Xin; Zhang, Shi; Liu, Gui-Dong; Kang, Wen-Yan; Tang, Hui-Dong; Ding, Jian-Qing; Chen, Sheng-Di

    2010-01-01

    Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder. Accumulating data indicate that astrocytes play an important role in the neuroinflammation related to the pathogenesis of AD. It has been shown that microglia and astrocytes are activated in AD brain and amyloid-beta (Abeta) can increase the expression of cyclooxygenase 2 (COX-2), interleukin-1, and interleukin-6. Suppressing the inflammatory response caused by activated astrocytes may help to inhibit the development of AD. Curcumin is a major constituent of the yellow curry spice turmeric and proved to be a potential anti-inflammatory drug in arthritis and colitis. There is a low age-adjusted prevalence of AD in India, a country where turmeric powder is commonly used as a culinary compound. Curcumin has been shown to suppress activated astroglia in amyloid-beta protein precursor transgenic mice. The real mechanism by which curcumin inhibits activated astroglia is poorly understood. Here we report that the expression of COX-2 and glial fibrillary acidic protein were enhanced and that of peroxisome proliferator-activated receptor gamma (PPARgamma) was decreased in Abeta(25-35)-treated astrocytes. In line with these results, nuclear factor-kappaB translocation was increased in the presence of Abeta. All these can be reversed by the pretreatment of curcumin. Furthermore, GW9662, a PPARgamma antagonist, can abolish the anti-inflammatory effect of curcumin. These results show that curcumin might act as a PPARgamma agonist to inhibit the inflammation in Abeta-treated astrocytes.

  7. Broad neutralization of calcium-permeable amyloid pore channels with a chimeric Alzheimer/Parkinson peptide targeting brain gangliosides.

    Science.gov (United States)

    Di Scala, Coralie; Yahi, Nouara; Flores, Alessandra; Boutemeur, Sonia; Kourdougli, Nazim; Chahinian, Henri; Fantini, Jacques

    2016-02-01

    Growing evidence supports a role for brain gangliosides in the pathogenesis of neurodegenerative diseases including Alzheimer's and Parkinson's. Recently we deciphered the ganglioside-recognition code controlling specific ganglioside binding to Alzheimer's β-amyloid (Aβ1-42) peptide and Parkinson's disease-associated protein α-synuclein. Cracking this code allowed us to engineer a short chimeric Aβ/α-synuclein peptide that recognizes all brain gangliosides. Here we show that ganglioside-deprived neural cells do no longer sustain the formation of zinc-sensitive amyloid pore channels induced by either Aβ1-42 or α-synuclein, as assessed by single-cell Ca(2+) fluorescence microscopy. Thus, amyloid channel formation, now considered a key step in neurodegeneration, is a ganglioside-dependent process. Nanomolar concentrations of chimeric peptide competitively inhibited amyloid pore formation induced by Aβ1-42 or α-synuclein in cultured neural cells. Moreover, this peptide abrogated the intracellular calcium increases induced by Parkinson's-associated mutant forms of α-synuclein (A30P, E46K and A53T). The chimeric peptide also prevented the deleterious effects of Aβ1-42 on synaptic vesicle trafficking and decreased the Aβ1-42-induced impairment of spontaneous activity in rat hippocampal slices. Taken together, these data show that the chimeric peptide has broad anti-amyloid pore activity, suggesting that a common therapeutic strategy based on the prevention of amyloid-ganglioside interactions is a reachable goal for both Alzheimer's and Parkinson's diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Benzothiazole aniline tetra(ethylene glycol) and 3-amino-1,2,4-triazole inhibit neuroprotection against amyloid peptides by catalase overexpression in vitro.

    Science.gov (United States)

    Chilumuri, Amrutha; Odell, Mark; Milton, Nathaniel G N

    2013-11-20

    Alzheimer's disease, Familial British dementia, Familial Danish dementia, Type 2 diabetes mellitus, plus Creutzfeldt-Jakob disease are associated with amyloid fibril deposition and oxidative stress. The antioxidant enzyme catalase is a neuroprotective amyloid binding protein. Herein the effects of catalase overexpression in SH-SY5Y neuronal cells on the toxicity of amyloid-β (Aβ), amyloid-Bri (ABri), amyloid-Dan (ADan), amylin (IAPP), and prion protein (PrP) peptides were determined. Results showed catalase overexpression was neuroprotective against Aβ, ABri, ADan, IAPP, and PrP peptides. The catalase inhibitor 3-amino-1,2,4-triazole (3-AT) and catalase-amyloid interaction inhibitor benzothiazole aniline tetra(ethylene glycol) (BTA-EG4) significantly enhanced neurotoxicity of amyloid peptides in catalase overexpressing neuronal cells. This suggests catalase neuroprotection involves breakdown of hydrogen peroxide (H2O2) plus a direct binding interaction between catalase and the Aβ, ABri, ADan, IAPP, and PrP peptides. Kisspeptin 45-50 had additive neuroprotective actions against the Aβ peptide in catalase overexpressing cells. The effects of 3-AT had an intracellular site of action, while catalase-amyloid interactions had an extracellular component. These results suggest that the 3-AT and BTA-EG4 compounds may be able to inhibit endogenous catalase mediated neuroprotection. Use of BTA-EG4, or compounds that inhibit catalase binding to amyloid peptides, as potential therapeutics for Neurodegenerative diseases may therefore result in unwanted effects.

  9. Benzothiazole Aniline Tetra(ethylene glycol) and 3-Amino-1,2,4-triazole Inhibit Neuroprotection against Amyloid Peptides by Catalase Overexpression in Vitro

    Science.gov (United States)

    2013-01-01

    Alzheimer’s disease, Familial British dementia, Familial Danish dementia, Type 2 diabetes mellitus, plus Creutzfeldt-Jakob disease are associated with amyloid fibril deposition and oxidative stress. The antioxidant enzyme catalase is a neuroprotective amyloid binding protein. Herein the effects of catalase overexpression in SH-SY5Y neuronal cells on the toxicity of amyloid-β (Aβ), amyloid-Bri (ABri), amyloid-Dan (ADan), amylin (IAPP), and prion protein (PrP) peptides were determined. Results showed catalase overexpression was neuroprotective against Aβ, ABri, ADan, IAPP, and PrP peptides. The catalase inhibitor 3-amino-1,2,4-triazole (3-AT) and catalase-amyloid interaction inhibitor benzothiazole aniline tetra(ethylene glycol) (BTA-EG4) significantly enhanced neurotoxicity of amyloid peptides in catalase overexpressing neuronal cells. This suggests catalase neuroprotection involves breakdown of hydrogen peroxide (H2O2) plus a direct binding interaction between catalase and the Aβ, ABri, ADan, IAPP, and PrP peptides. Kisspeptin 45–50 had additive neuroprotective actions against the Aβ peptide in catalase overexpressing cells. The effects of 3-AT had an intracellular site of action, while catalase-amyloid interactions had an extracellular component. These results suggest that the 3-AT and BTA-EG4 compounds may be able to inhibit endogenous catalase mediated neuroprotection. Use of BTA-EG4, or compounds that inhibit catalase binding to amyloid peptides, as potential therapeutics for Neurodegenerative diseases may therefore result in unwanted effects. PMID:23968537

  10. A cocoa peptide protects Caenorhabditis elegans from oxidative stress and β-amyloid peptide toxicity.

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    Patricia Martorell

    Full Text Available BACKGROUND: Cocoa and cocoa-based products contain different compounds with beneficial properties for human health. Polyphenols are the most frequently studied, and display antioxidant properties. Moreover, protein content is a very interesting source of antioxidant bioactive peptides, which can be used therapeutically for the prevention of age-related diseases. METHODOLOGY/PRINCIPAL FINDINGS: A bioactive peptide, 13L (DNYDNSAGKWWVT, was obtained from a hydrolyzed cocoa by-product by chromatography. The in vitro inhibition of prolyl endopeptidase (PEP was used as screening method to select the suitable fraction for peptide identification. Functional analysis of 13L peptide was achieved using the transgenic Caenorhabditis elegans strain CL4176 expressing the human Aβ₁₋₄₂ peptide as a pre-clinical in vivo model for Alzheimer's disease. Among the peptides isolated, peptide 13L (1 µg/mL showed the highest antioxidant activity (P≤0.001 in the wild-type strain (N2. Furthermore, 13L produced a significant delay in body paralysis in strain CL4176, especially in the 24-47 h period after Aβ₁₋₄₂ peptide induction (P≤0.0001. This observation is in accordance with the reduction of Aβ deposits in CL4176 by western blot. Finally, transcriptomic analysis in wild-type nematodes treated with 13L revealed modulation of the proteosomal and synaptic functions as the main metabolic targets of the peptide. CONCLUSIONS/SIGNIFICANCE: These findings suggest that the cocoa 13L peptide has antioxidant activity and may reduce Aβ deposition in a C. elegans model of Alzheimer's disease; and therefore has a putative therapeutic potential for prevention of age-related diseases. Further studies in murine models and humans will be essential to analyze the effectiveness of the 13L peptide in higher animals.

  11. Computational identification of potential multitarget treatments for ameliorating the adverse effects of amyloid-beta on synaptic plasticity

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    Thomas J. Anastasio

    2014-05-01

    Full Text Available The leading hypothesis on Alzheimer Disease (AD is that it is caused by buildup of the peptide amyloid-beta (Abeta, which initially causes dysregulation of synaptic plasticity and eventually causes destruction of synapses and neurons. Pharmacological efforts to limit Abeta buildup have proven ineffective, and this raises the twin challenges of understanding the adverse effects of Abeta on synapses and of suggesting pharmacological means to prevent it. The purpose of this paper is to initiate a computational approach to understanding the dysregulation by Abeta of synaptic plasticity and to offer suggestions whereby combinations of various chemical compounds could be arrayed against it. This data-driven approach confronts the complexity of synaptic plasticity by representing findings from the literature in a course-grained manner, and focuses on understanding the aggregate behavior of many molecular interactions. The same set of interactions is modeled by two different computer programs, each written using a different programming modality: one imperative, the other declarative. Both programs compute the same results over an extensive test battery, providing an essential crosscheck. Then the imperative program is used for the computationally intensive purpose of determining the effects on the model of every combination of ten different compounds, while the declarative program is used to analyze model behavior using temporal logic. Together these two model implementations offer new insights into the mechanisms by which Abeta dysregulates synaptic plasticity and suggest many drug combinations that potentially may reduce or prevent it.

  12. Quantifying the pattern of beta/A4 amyloid protein distribution in Alzheimer's disease by image analysis.

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    Bruce, C V; Clinton, J; Gentleman, S M; Roberts, G W; Royston, M C

    1992-04-01

    We have undertaken a study of the distribution of the beta/A4 amyloid deposited in the cerebral cortex in Alzheimer's disease. Previous studies which have examined the differential distribution of amyloid in the cortex in order to determine the laminar pattern of cortical pathology have not proved to be conclusive. We have developed an alternative method for the solution of this problem. It involves the immunostaining of sections followed by computer-enhanced image analysis. A mathematical model is then used to describe both the amount and the pattern of amyloid across the cortex. This method is both accurate and reliable and also removes many of the problems concerning inter and intra-rater variability in measurement. This method will provide the basis for further quantitative studies on the differential distribution of amyloid in Alzheimer's disease and other cases of dementia where cerebral amyloidosis occurs.

  13. Effect of osmolytes on the conformation and aggregation of some amyloid peptides: CD spectroscopic data

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    Mohammed Inayathullah

    2016-06-01

    Full Text Available Protein misfolding and aggregation are responsible for a large number of diseases called protein conformational diseases or disorders that include Alzheimer׳s disease, Huntington׳s diseases, Prion related encephalopathies and type-II diabetes (http://dx.doi.org/10.1038/35041139 (Kopito and Ron, 2000 [1]. A variety of studies have shown that some small organic molecules, known as osmolytes have the ability to stabilize native conformation of proteins and prevent misfolding and aggregation (http://www.la-press.com/article.php?article_id=447 (Zhao et al., 2008 [2]. It has been shown that certain short segment or fragment of respective proteins can also form amyloids, and the segments also promote the aggregation in the full-length protein (http://dx.doi.org/10.2174/0929867023369187 (Gazit, 2002 [3]. This article presents circular dichroism spectroscopic data on conformational analysis and effect of osmolytes on Aβ peptide fragments, different lengths of polyglutamine peptide and the amyloidogenic segment of islet amyloid polypeptide.

  14. Neuroprotective Effects of Pomegranate Peel Extract after Chronic Infusion with AmyloidPeptide in Mice

    Science.gov (United States)

    Morzelle, Maressa Caldeira; Salgado, Jocelem Mastrodi; Telles, Milena; Mourelle, Danilo; Bachiega, Patricia; Buck, Hudson Sousa

    2016-01-01

    Alzheimer’s disease is a chronic and degenerative condition that had no treatment until recently. The current therapeutic strategies reduce progression of the disease but are expensive and commonly cause side effects that are uncomfortable for treated patients. Functional foods to prevent and/or treat many conditions, including neurodegenerative diseases, represent a promising field of study currently gaining attention. To this end, here we demonstrate the effects of pomegranate (Punica granatum) peel extract (PPE) regarding spatial memory, biomarkers of neuroplasticity, oxidative stress and inflammation in a mouse model of neurodegeneration. Male C57Bl/6 mice were chronically infused for 35 days with amyloidpeptide 1–42 (Aβ) or vehicle (control) using mini-osmotic pumps. Another group, also infused with Aβ, was treated with PPE (p.o.– βA+PPE, 800 mg/kg/day). Spatial memory was evaluated in the Barnes maze. Animals treated with PPE and in the control group exhibited a reduction in failure to find the escape box, a finding that was not observed in the Aβ group. The consumption of PPE reduced amyloid plaque density, increased the expression of neurotrophin BDNF and reduced the activity of acetylcholinesterase enzyme. A reduction in lipid peroxidation and in the concentration of the pro-inflammatory cytokine TNF-α was also observed in the PPE group. No hepatic lesions were observed in animals treated with PPE. In conclusion, administration of pomegranate peel extract has neuroprotective effects involving multiple mechanisms to prevent establishment and progression of the neurodegenerative process induced by infusion with amyloidpeptide in mice. PMID:27829013

  15. Chaperones ameliorate beta cell dysfunction associated with human islet amyloid polypeptide overexpression.

    Directory of Open Access Journals (Sweden)

    Lisa Cadavez

    Full Text Available In type 2 diabetes, beta-cell dysfunction is thought to be due to several causes, one being the formation of toxic protein aggregates called islet amyloid, formed by accumulations of misfolded human islet amyloid polypeptide (hIAPP. The process of hIAPP misfolding and aggregation is one of the factors that may activate the unfolded protein response (UPR, perturbing endoplasmic reticulum (ER homeostasis. Molecular chaperones have been described to be important in regulating ER response to ER stress. In the present work, we evaluate the role of chaperones in a stressed cellular model of hIAPP overexpression. A rat pancreatic beta-cell line expressing hIAPP exposed to thapsigargin or treated with high glucose and palmitic acid, both of which are known ER stress inducers, showed an increase in ER stress genes when compared to INS1E cells expressing rat IAPP or INS1E control cells. Treatment with molecular chaperone glucose-regulated protein 78 kDa (GRP78, also known as BiP or protein disulfite isomerase (PDI, and chemical chaperones taurine-conjugated ursodeoxycholic acid (TUDCA or 4-phenylbutyrate (PBA, alleviated ER stress and increased insulin secretion in hIAPP-expressing cells. Our results suggest that the overexpression of hIAPP induces a stronger response of ER stress markers. Moreover, endogenous and chemical chaperones are able to ameliorate induced ER stress and increase insulin secretion, suggesting that improving chaperone capacity can play an important role in improving beta-cell function in type 2 diabetes.

  16. Beta-amyloid precursor protein transgenic mice that harbor diffuse A beta deposits but do not form plaques show increased ischemic vulnerability: role of inflammation

    Czech Academy of Sciences Publication Activity Database

    Koistinaho, M.; Kettunen, M. I.; Goldsteins, G.; Keinänen, R.; Salminen, A.; Ort, Michael; Bureš, Jan; Liu, D.; Kauppinen, R. A.; Higgins, L. S.; Koistinaho, J.

    2002-01-01

    Roč. 99, č. 3 (2002), s. 1610-1615 ISSN 0027-8424 R&D Projects: GA ČR GA309/00/1656 Institutional research plan: CEZ:AV0Z5011922 Keywords : Beta-amyloid * Alzheimer disease * brain ischemia Subject RIV: FH - Neurology Impact factor: 10.701, year: 2002

  17. Beyond the neurotransmitter-focused approach in treating Alzheimer's disease: drugs targeting beta-amyloid and tau protein.

    Science.gov (United States)

    Panza, Francesco; Solfrizzi, Vincenzo; Frisardi, Vincenza; Imbimbo, Bruno P; Capurso, Cristiano; D'Introno, Alessia; Colacicco, Anna M; Seripa, Davide; Vendemiale, Gianluigi; Capurso, Antonio; Pilotto, Alberto

    2009-12-01

    Drugs currently used to treat Alzheimer's Disease (AD) have limited therapeutic value and do not affect the main neuropathological hallmarks of the disease, i.e., senile plaques and neurofibrillar tangles. Senile plaques are mainly formed of beta-amyloid (Abeta), a 42-aminoacid peptide. Neurofibrillar tangles are composed of paired helical filaments of hyperphosphorylated tau protein. New, potentially disease-modifying, therapeutic approaches are targeting Abeta and tau protein. Drugs directed against Abeta include active and passive immunization, that have been found to accelerate Abeta clearance from the brain. The most developmentally advanced monoclonal antibody directly targeting Abeta is bapineuzumab, now being studied in a large Phase III clinical trial. Compounds that interfere with proteases regulating Abeta formation from amyloid precursor protein (APP) are also actively pursued. The discovery of inhibitors of beta-secretase, the enzyme that regulates the first step of the amyloidogenic metabolism of APP, has been revealed to be particularly difficult due to inherent medicinal chemistry problems, and only one compound (CTS-21166) has reached clinical testing. Conversely, several compounds that inhibit gamma-secretase, the pivotal enzyme that generates Abeta, have been identified, the most advanced being LY-450139 (semagacestat), now in Phase III clinical development. Compounds that stimulate alpha-secretase, the enzyme responsible for the non-amyloidogenic metabolism of APP, are also being developed, and one of them, EHT-0202, has recently entered Phase II testing. Potent inhibitors of Abeta aggregation have also been identified, and one of such compounds, PBT-2, has provided encouraging neuropsychological results in a recently completed Phase II study. Therapeutic approaches directed against tau protein include inhibitors of glycogen synthase kinase- 3 (GSK-3), the enzyme responsible for tau phosphorylation and tau protein aggregation inhibitors. NP-12

  18. Dynamic behavior of small heat shock protein inhibition on amyloid fibrillization of a small peptide (SSTSAA) from RNase A

    International Nuclear Information System (INIS)

    Xi, Dong; Dong, Xiao; Deng, Wei; Lai, Luhua

    2011-01-01

    Highlights: ► Mechanism of small heat shock protein inhibition on fibril formation was studied. ► Peptide SSTSAA with modified ends was used for amyloid fibril formation. ► FRET signal was followed during the fibril formation. ► Mj HSP16.5 inhibits fibril formation when introduced in the lag phase. ► Mj HSP16.5 slows down fibril formation when introduced after the lag phase. -- Abstract: Small heat shock proteins, a class of molecular chaperones, are reported to inhibit amyloid fibril formation in vitro, while the mechanism of inhibition remains unknown. In the present study, we investigated the mechanism by which Mj HSP16.5 inhibits amyloid fibril formation of a small peptide (SSTSAA) from RNase A. A model peptide (dansyl-SSTSAA-W) was designed by introducing a pair of fluorescence resonance energy transfer (FRET) probes into the peptide, allowing for the monitoring of fibril formation by this experimental model. Mj HSP16.5 completely inhibited fibril formation of the model peptide at a molar ratio of 1:120. The dynamic process of fibril formation, revealed by FRET, circular dichroism, and electron microscopy, showed a lag phase of about 2 h followed by a fast growth period. The effect of Mj HSP16.5 on amyloid fibril formation was investigated by adding it into the incubation solution during different growth phases. Adding Mj HSP16.5 to the incubating peptide before or during the lag phase completely inhibited fibril formation. However, introducing Mj HSP16.5 after the lag phase only slowed down the fibril formation process by adhering to the already formed fibrils. These findings provide insight into the inhibitory roles of small heat shock proteins on amyloid fibril formation at the molecular level.

  19. Dynamic behavior of small heat shock protein inhibition on amyloid fibrillization of a small peptide (SSTSAA) from RNase A

    Energy Technology Data Exchange (ETDEWEB)

    Xi, Dong [BNLMS, State Key Laboratory of Structural Chemistry for Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Center for Theoretical Biology, Peking University, Beijing 100871 (China); Dong, Xiao; Deng, Wei [BNLMS, State Key Laboratory of Structural Chemistry for Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Lai, Luhua, E-mail: lhlai@pku.edu.cn [BNLMS, State Key Laboratory of Structural Chemistry for Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Center for Theoretical Biology, Peking University, Beijing 100871 (China)

    2011-12-09

    Highlights: Black-Right-Pointing-Pointer Mechanism of small heat shock protein inhibition on fibril formation was studied. Black-Right-Pointing-Pointer Peptide SSTSAA with modified ends was used for amyloid fibril formation. Black-Right-Pointing-Pointer FRET signal was followed during the fibril formation. Black-Right-Pointing-Pointer Mj HSP16.5 inhibits fibril formation when introduced in the lag phase. Black-Right-Pointing-Pointer Mj HSP16.5 slows down fibril formation when introduced after the lag phase. -- Abstract: Small heat shock proteins, a class of molecular chaperones, are reported to inhibit amyloid fibril formation in vitro, while the mechanism of inhibition remains unknown. In the present study, we investigated the mechanism by which Mj HSP16.5 inhibits amyloid fibril formation of a small peptide (SSTSAA) from RNase A. A model peptide (dansyl-SSTSAA-W) was designed by introducing a pair of fluorescence resonance energy transfer (FRET) probes into the peptide, allowing for the monitoring of fibril formation by this experimental model. Mj HSP16.5 completely inhibited fibril formation of the model peptide at a molar ratio of 1:120. The dynamic process of fibril formation, revealed by FRET, circular dichroism, and electron microscopy, showed a lag phase of about 2 h followed by a fast growth period. The effect of Mj HSP16.5 on amyloid fibril formation was investigated by adding it into the incubation solution during different growth phases. Adding Mj HSP16.5 to the incubating peptide before or during the lag phase completely inhibited fibril formation. However, introducing Mj HSP16.5 after the lag phase only slowed down the fibril formation process by adhering to the already formed fibrils. These findings provide insight into the inhibitory roles of small heat shock proteins on amyloid fibril formation at the molecular level.

  20. Targeting the Nrf2/Amyloid-Beta Liaison in Alzheimer's Disease: A Rational Approach.

    Science.gov (United States)

    Simoni, Elena; Serafini, Melania M; Caporaso, Roberta; Marchetti, Chiara; Racchi, Marco; Minarini, Anna; Bartolini, Manuela; Lanni, Cristina; Rosini, Michela

    2017-07-19

    Amyloid is a prominent feature of Alzheimer's disease (AD). Yet, a linear linkage between amyloidpeptide (Aβ) and the disease onset and progression has recently been questioned. In this context, the crucial partnership between Aβ and Nrf2 pathways is acquiring paramount importance, offering prospects for deciphering the Aβ-centered disease network. Here, we report on a new class of antiaggregating agents rationally designed to simultaneously activate transcription-based antioxidant responses, whose lead 1 showed interesting properties in a preliminary investigation. Relying on the requirements of Aβ recognition, we identified the catechol derivative 12. In SH-SY5Y neuroblastoma cells, 12 combined remarkable free radical scavenger properties to the ability to trigger the Nrf2 pathway and induce the Nrf2-dependent defensive gene NQO1 by means of electrophilic activation of the transcriptional response. Moreover, 12 prevented the formation of cytotoxic stable oligomeric intermediates, being significantly more effective, and per se less toxic, than prototype 1. More importantly, as different chemical features were exploited to regulate Nrf2 and Aβ activities, the two pathways could be tuned independently. These findings point to compound 12 and its derivatives as promising tools for investigating the therapeutic potential of the Nrf2/Aβ cellular network, laying foundation for generating new drug leads to confront AD.

  1. Association between amylin and amyloidpeptides in plasma in the context of apolipoprotein E4 allele.

    Directory of Open Access Journals (Sweden)

    Wei Qiao Qiu

    Full Text Available Amylin, a pancreatic peptide that readily crosses the blood brain barrier (BBB, and amyloid-beta peptide (Aβ, the main component of amyloid plaques and a major component of Alzheimer's disease (AD pathology in the brain, share several features. These include having similar β-sheet secondary structures, binding to the same receptor, and being degraded by the same protease. Thus, amylin may be associated with Aβ, but the nature of their relationship remains unclear. In this study, we used human samples to study the relationship between plasma amylin and Aβ in the context of the apolipoprotein E alleles (ApoE. We found that concentrations of Aβ1-42 (P<0.0001 and Aβ1-40 (P<0.0001 increased with each quartile increase of amylin. Using multivariate regression analysis, the study sample showed that plasma amylin was associated with Aβ1-42 (β = +0.149, SE = 0.025, P<0.0001 and Aβ1-40 (β = +0.034, SE = 0.016, P = 0.04 as an outcome after adjusting for age, gender, ethnicity, ApoE4, BMI, diabetes, stroke, kidney function and lipid profile. This positive association between amylin and Aβ1-42 in plasma was found regardless of the ApoE genotype. In contrast, the relationship between amylin and Aβ1-40 in plasma seen in ApoE4 non-carriers disappeared in the presence of ApoE4. Using AD mouse models, our recent study demonstrates that intraperitoneal (i.p. injection of synthetic amylin enhances the removal of Aβ from the brain into blood, thus resulting in increased blood levels of both amylin and Aβ. The positive association between amylin and Aβ, especially Aβ1-42, in human blood samples is probably relevant to the findings in the AD mouse models. The presence of ApoE4 may attenuate amylin's capacity to remove Aβ, especially Aβ1-40, from the AD brain.

  2. Alzheimer’s Disease Risk Gene CD33 Inhibits Microglial Uptake of Amyloid Beta

    Science.gov (United States)

    Griciuc, Ana; Serrano-Pozo, Alberto; Parrado, Antonio R.; Lesinski, Andrea N.; Asselin, Caroline N.; Mullin, Kristina; Hooli, Basavaraj; Choi, Se Hoon; Hyman, Bradley T.; Tanzi, Rudolph E.

    2013-01-01

    SUMMARY The transmembrane protein CD33 is a sialic acid-binding immunoglobulin-like lectin that regulates innate immunity but has no known functions in the brain. We have previously shown that the CD33 gene is a risk factor for Alzheimer’s disease (AD). Here, we observed increased expression of CD33 in microglial cells in AD brain. The minor allele of the CD33 SNP rs3865444, which confers protection against AD, was associated with reductions in both CD33 expression and insoluble amyloid beta 42 (Aβ42) levels in AD brain. Furthermore, the numbers of CD33-immunoreactive microglia were positively correlated with insoluble Aβ42 levels and plaque burden in AD brain. CD33 inhibited uptake and clearance of Aβ42 in microglial cell cultures. Finally, brain levels of insoluble Aβ42 as well as amyloid plaque burden were markedly reduced in APPSwe/PS1ΔE9/CD33−/− mice. Therefore, CD33 inactivation mitigates Aβ pathology and CD33 inhibition could represent a novel therapy for AD. PMID:23623698

  3. Alzheimer's disease risk gene CD33 inhibits microglial uptake of amyloid beta.

    Science.gov (United States)

    Griciuc, Ana; Serrano-Pozo, Alberto; Parrado, Antonio R; Lesinski, Andrea N; Asselin, Caroline N; Mullin, Kristina; Hooli, Basavaraj; Choi, Se Hoon; Hyman, Bradley T; Tanzi, Rudolph E

    2013-05-22

    The transmembrane protein CD33 is a sialic acid-binding immunoglobulin-like lectin that regulates innate immunity but has no known functions in the brain. We have previously shown that the CD33 gene is a risk factor for Alzheimer's disease (AD). Here, we observed increased expression of CD33 in microglial cells in AD brain. The minor allele of the CD33 SNP rs3865444, which confers protection against AD, was associated with reductions in both CD33 expression and insoluble amyloid beta 42 (Aβ42) levels in AD brain. Furthermore, the numbers of CD33-immunoreactive microglia were positively correlated with insoluble Aβ42 levels and plaque burden in AD brain. CD33 inhibited uptake and clearance of Aβ42 in microglial cell cultures. Finally, brain levels of insoluble Aβ42 as well as amyloid plaque burden were markedly reduced in APP(Swe)/PS1(ΔE9)/CD33(-/-) mice. Therefore, CD33 inactivation mitigates Aβ pathology and CD33 inhibition could represent a novel therapy for AD. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Indirubin-3′-monoxime suppresses amyloid-beta-induced apoptosis by inhibiting tau hyperphosphorylation

    Institute of Scientific and Technical Information of China (English)

    Shu-gang Zhang; Xiao-shan Wang; Ying-dong Zhang; Qing Di; Jing-ping Shi; Min Qian; Li-gang Xu; Xing-jian Lin; Jie Lu

    2016-01-01

    Indirubin-3′-monoxime is an effective inhibitor of cyclin-dependent protein kinases, and may play an obligate role in neuronal apopto-sis in Alzheimer’s disease. Here, we found that indirubin-3′-monoxime improved the morphology and increased the survival rate of SH-SY5Y cells exposed to amyloid-beta 25–35 (Aβ25–35), and also suppressed apoptosis by reducing tau phosphorylation at Ser199 and Thr205. Furthermore, indirubin-3′-monoxime inhibited phosphorylation of glycogen synthase kinase-3β (GSK-3β). Our results suggest that in-dirubin-3′-monoxime reduced Aβ25–35-induced apoptosis by suppressing tau hyperphosphorylationvia a GSK-3β-mediated mechanism. Indirubin-3′-monoxime is a promising drug candidate for Alzheimer’s disease.

  5. Memantine prevents memory consolidation failure induced by soluble beta amyloid in rats

    Directory of Open Access Journals (Sweden)

    Paolo eTucci

    2014-09-01

    Full Text Available It has been well documented that β-amyloid peptide accumulation and aggregation in the brain plays a crucial role in the pathophysiology of Alzheimer’s disease (AD. However, a new orientation of the amyloid cascade hypothesis has evidenced that soluble forms of the peptide (sAβ are involved in Aβ-induced cognitive impairment and cause rapid disruption of the synaptic mechanisms underlying memory. The primary aim of this study was to elucidate the effects of sAβ, acutely injected intracerebrally (i.c.v., 4 µM, on the short term and long term memory of young adult male rats, by using the novel object recognition task. Glutamatergic receptors have been proposed as mediating the effect of Aβ on synaptic plasticity and memory. Thus, we also investigated the effects of sAβ on prefrontal cortex (PFC glutamate release and the specific contribution of N-methyl-D-aspartate (NMDA receptor modulation to the effects of sAβ administration on the cognitive parameters evaluated. We found that a single i.c.v. injection of sAβ 2h before testing did not alter the ability of rats to differentiate between a familiar and a novel object, in a short term memory test, while it was able to negatively affect consolidation/retrieval of long term memory. Moreover, a significant increase of glutamate levels was found in PFC of rats treated with the peptide 2 h earlier. Interestingly, memory deficit induced by sAβ was reversed by a NMDA-receptor antagonist, memantine (5 mg/kg i.p, administered immediately after the familiarization trial (T1. On the contrary, memantine administered 30 min before T1 trial, was not able to rescue long term memory impairment. Taken together, our results suggest that an acute i.c.v. injection of sAβ peptide interferes with the consolidation/retrieval of long term memory. Moreover, such sAβ-induced effect indicates the involvement of glutamatergic system, proposing that NMDA receptor inhibition might prevent or lead to the recovery of

  6. The interaction with gold suppresses fiber-like conformations of the amyloid β (16-22) peptide

    Science.gov (United States)

    Bellucci, Luca; Ardèvol, Albert; Parrinello, Michele; Lutz, Helmut; Lu, Hao; Weidner, Tobias; Corni, Stefano

    2016-04-01

    Inorganic surfaces and nanoparticles can accelerate or inhibit the fibrillation process of proteins and peptides, including the biomedically relevant amyloid β peptide. However, the microscopic mechanisms that determine such an effect are still poorly understood. By means of large-scale, state-of-the-art enhanced sampling molecular dynamics simulations, here we identify an interaction mechanism between the segments 16-22 of the amyloid β peptide, known to be fibrillogenic by itself, and the Au(111) surface in water that leads to the suppression of fiber-like conformations from the peptide conformational ensemble. Moreover, thanks to advanced simulation analysis techniques, we characterize the conformational selection vs. induced fit nature of the gold effect. Our results disclose an inhibition mechanism that is rooted in the details of the microscopic peptide-surface interaction rather than in general phenomena such as peptide sequestration from the solution.Inorganic surfaces and nanoparticles can accelerate or inhibit the fibrillation process of proteins and peptides, including the biomedically relevant amyloid β peptide. However, the microscopic mechanisms that determine such an effect are still poorly understood. By means of large-scale, state-of-the-art enhanced sampling molecular dynamics simulations, here we identify an interaction mechanism between the segments 16-22 of the amyloid β peptide, known to be fibrillogenic by itself, and the Au(111) surface in water that leads to the suppression of fiber-like conformations from the peptide conformational ensemble. Moreover, thanks to advanced simulation analysis techniques, we characterize the conformational selection vs. induced fit nature of the gold effect. Our results disclose an inhibition mechanism that is rooted in the details of the microscopic peptide-surface interaction rather than in general phenomena such as peptide sequestration from the solution. Electronic supplementary information (ESI

  7. Clinical and cost implications of amyloid beta detection with amyloid beta positron emission tomography imaging in early Alzheimer's disease - the case of florbetapir.

    Science.gov (United States)

    Hornberger, John; Bae, Jay; Watson, Ian; Johnston, Joe; Happich, Michael

    2017-04-01

    Amyloid beta (Aβ) positron emission tomography (PET) imaging helps estimate Aβ neuritic plaque density in patients with cognitive impairment who are under evaluation for Alzheimer's disease (AD). This study aims to evaluate the cost-effectiveness of the Aβ-PET scan as an adjunct to standard diagnostic assessment for diagnosis of AD in France, using florbetapir as an example. A state-transition probability analysis was developed adopting the French Health Technology Assessment (HTA) perspective per guidance. Parameters included test characteristics, rate of cognitive decline, treatment effect, costs, and quality of life. Additional scenarios assessed the validity of the analytical framework, including: (1) earlier evaluation/treatment; (2) cerebrospinal fluid (CSF) as a comparator; and (3) use of other diagnostic procedures. Outputs included differences in quality-adjusted life years (QALYs), costs, and incremental cost-effectiveness ratios (ICERs). All benefits and costs were discounted for time preferences. Sensitivity analyses were performed to assess the robustness of findings and key influencers of outcomes. Aβ-PET used as an adjunct to standard diagnostic assessment increased QALYs by 0.021 years and 10 year costs by €470 per patient. The ICER was €21,888 per QALY gained compared to standard diagnostic assessment alone. When compared with CSF, Aβ-PET costs €24,084 per QALY gained. In other scenarios, Aβ-PET was consistently cost-effective relative to the commonly used affordability threshold (€40,000 per QALY). Over 95% of simulations in the sensitivity analysis were cost-effective. Aβ-PET is projected to affordably increase QALYs from the French HTA perspective per guidance over a range of clinical scenarios, comparators, and input parameters.

  8. Modeling of Platinum-Aryl Interaction with AmyloidPeptide.

    Science.gov (United States)

    Turner, Matthew; Platts, James A; Deeth, Robert J

    2016-03-08

    Ligand field molecular mechanics (LFMM), density functional theory (DFT), and semiempirical PM7 methods are used to study the binding of two Pt(II)-L systems to an N-terminal fragment of the amyloidpeptide, where L = 2,2-bipyridyl or 1,10-phenanthroline. Molecular dynamics simulations are used to explore the conformational freedom of the peptide using LFMM combined with AMBER molecular mechanics parameters. We establish a modeling protocol, allowing for identification and analysis of favorable platinum-binding modes and peptide conformations. Preferred binding modes are identified for each ligand investigated; metal coordination occurs via Nε in His residues for both ligands--His6ε-His13ε and His6ε-His14ε for the bipyridyl and phenanthroline ligands, respectively. The observed change in binding mode for the different ligands suggests that the binding mode of these platinum-based structures can be controlled by the choice of ligand. In the bipy systems, Boltzmann population at 310 K is dominated by a single conformer, while in the phenanthroline case, three conformations make significant contributions to the ensemble. The relative stability of these conformations is due to the inherent stability of binding platinum via Nε in addition to subtle H-bonding effects.

  9. Ginsenoside compound K promotes β-amyloid peptide clearance in primary astrocytes via autophagy enhancement.

    Science.gov (United States)

    Guo, Jinhui; Chang, Li; Zhang, Xin; Pei, Sujuan; Yu, Meishuang; Gao, Jianlian

    2014-10-01

    The aim of the present study was to investigate the effect of ginsenoside compound K on β-amyloid (Aβ) peptide clearance in primary astrocytes. Aβ degradation in primary astrocytes was determined using an intracellular Aβ clearance assay. Aggregated LC3 in astrocyte cells, which is a marker for the level of autophagy, was detected using laser scanning confocal microscope. The effect of compound K on the mammalian target of rapamycin (mTOR)/autophagy pathway was determined using western blot analysis, and an enzyme-linked immunosorbent assay was used for Aβ detection. The results demonstrated that compound K promoted the clearance of Aβ and enhanced autophagy in primary astrocytes. In addition, it was found that phosphorylation of mTOR was inhibited by compound K, which may have contributed to the enhanced autophagy. In conclusion, compound K promotes Aβ clearance by enhancing autophagy via the mTOR signaling pathway in primary astrocytes.

  10. Powerful beneficial effects of benfotiamine on cognitive impairment and beta-amyloid deposition in amyloid precursor protein/presenilin-1 transgenic mice.

    Science.gov (United States)

    Pan, Xiaoli; Gong, Neng; Zhao, Jing; Yu, Zhe; Gu, Fenghua; Chen, Jia; Sun, Xiaojing; Zhao, Lei; Yu, Meijing; Xu, Zhiru; Dong, Wenxin; Qin, Yan; Fei, Guoqiang; Zhong, Chunjiu; Xu, Tian-Le

    2010-05-01

    Reduction of glucose metabolism in brain is one of the main features of Alzheimer's disease. Thiamine (vitamin B1)-dependent processes are critical in glucose metabolism and have been found to be impaired in brains from patients with Alzheimer's disease. However, thiamine treatment exerts little beneficial effect in these patients. Here, we tested the effect of benfotiamine, a thiamine derivative with better bioavailability than thiamine, on cognitive impairment and pathology alterations in a mouse model of Alzheimer's disease, the amyloid precursor protein/presenilin-1 transgenic mouse. We show that after a chronic 8 week treatment, benfotiamine dose-dependently enhanced the spatial memory of amyloid precursor protein/presenilin-1 mice in the Morris water maze test. Furthermore, benfotiamine effectively reduced both amyloid plaque numbers and phosphorylated tau levels in cortical areas of the transgenic mice brains. Unexpectedly, these effects were not mimicked by another lipophilic thiamine derivative, fursultiamine, although both benfotiamine and fursultiamine were effective in increasing the levels of free thiamine in the brain. Most notably, benfotiamine, but not fursultiamine, significantly elevated the phosphorylation level of glycogen synthase kinase-3alpha and -3beta, and reduced their enzymatic activities in the amyloid precursor protein/presenilin-1 transgenic brain. Therefore, in the animal Alzheimer's disease model, benfotiamine appears to improve the cognitive function and reduce amyloid deposition via thiamine-independent mechanisms, which are likely to include the suppression of glycogen synthase kinase-3 activities. These results suggest that, unlike many other thiamine-related drugs, benfotiamine may be beneficial for clinical Alzheimer's disease treatment.

  11. Lattice model for amyloid peptides: OPEP force field parametrization and applications to the nucleus size of Alzheimer’s peptides

    Energy Technology Data Exchange (ETDEWEB)

    Tran, Thanh Thuy; Nguyen, Phuong H., E-mail: phuong.nguyen@ibpc.fr; Derreumaux, Philippe, E-mail: philippe.derreumaux@ibpc.fr [Laboratoire de Biochimie Théorique, UPR 9080, CNRS, Université Denis Diderot, Sorbonne Paris Cité IBPC, 13 rue Pierre et Marie Curie, 75005 Paris (France)

    2016-05-28

    Coarse-grained protein lattice models approximate atomistic details and keep the essential interactions. They are, therefore, suitable for capturing generic features of protein folding and amyloid formation at low computational cost. As our aim is to study the critical nucleus sizes of two experimentally well-characterized peptide fragments Aβ{sub 16−22} and Aβ{sub 37−42} of the full length Aβ{sub 1−42} Alzheimer’s peptide, it is important that simulations with the lattice model reproduce all-atom simulations. In this study, we present a comprehensive force field parameterization based on the OPEP (Optimized Potential for Efficient protein structure Prediction) force field for an on-lattice protein model, which incorporates explicitly the formation of hydrogen bonds and directions of side-chains. Our bottom-up approach starts with the determination of the best lattice force parameters for the Aβ{sub 16−22} dimer by fitting its equilibrium parallel and anti-parallel β-sheet populations to all-atom simulation results. Surprisingly, the calibrated force field is transferable to the trimer of Aβ{sub 16−22} and the dimer and trimer of Aβ{sub 37−42}. Encouraged by this finding, we characterized the free energy landscapes of the two decamers. The dominant structure of the Aβ{sub 16−22} decamer matches the microcrystal structure. Pushing the simulations for aggregates between 4-mer and 12-mer suggests a nucleus size for fibril formation of 10 chains. In contrast, the Aβ{sub 37−42} decamer is largely disordered with mixed by parallel and antiparallel chains, suggesting that the nucleus size is >10 peptides. Our refined force field coupled to this on-lattice model should provide useful insights into the critical nucleation number associated with neurodegenerative diseases.

  12. Targeting Beta-Amyloid at the CSF: A New Therapeutic Strategy in Alzheimer's Disease.

    Science.gov (United States)

    Menendez-Gonzalez, Manuel; Padilla-Zambrano, Huber S; Alvarez, Gabriel; Capetillo-Zarate, Estibaliz; Tomas-Zapico, Cristina; Costa, Agustin

    2018-01-01

    Although immunotherapies against the amyloid-β (Aβ) peptide tried so date failed to prove sufficient clinical benefit, Aβ still remains the main target in Alzheimer's disease (AD). This article aims to show the rationale of a new therapeutic strategy: clearing Aβ from the CSF continuously (the "CSF-sink" therapeutic strategy). First, we describe the physiologic mechanisms of Aβ clearance and the resulting AD pathology when these mechanisms are altered. Then, we review the experiences with peripheral Aβ-immunotherapy and discuss the related hypothesis of the mechanism of action of "peripheral sink." We also present Aβ-immunotherapies acting on the CNS directly. Finally, we introduce alternative methods of removing Aβ including the "CSF-sink" therapeutic strategy. As soluble peptides are in constant equilibrium between the ISF and the CSF, altering the levels of Aβ oligomers in the CSF would also alter the levels of such proteins in the brain parenchyma. We conclude that interventions based in a "CSF-sink" of Aβ will probably produce a steady clearance of Aβ in the ISF and therefore it may represent a new therapeutic strategy in AD.

  13. Biological markers of amyloid beta-related mechanisms in Alzheimer's disease.

    LENUS (Irish Health Repository)

    Hampel, Harald

    2012-02-01

    Recent research progress has given detailed knowledge on the molecular pathogenesis of Alzheimer\\'s disease (AD), which has been translated into an intense, ongoing development of disease-modifying treatments. Most new drug candidates are targeted on inhibiting amyloid beta (Abeta) production and aggregation. In drug development, it is important to co-develop biomarkers for Abeta-related mechanisms to enable early diagnosis and patient stratification in clinical trials, and to serve as tools to identify and monitor the biochemical effect of the drug directly in patients. Biomarkers are also requested by regulatory authorities to serve as safety measurements. Molecular aberrations in the AD brain are reflected in the cerebrospinal fluid (CSF). Core CSF biomarkers include Abeta isoforms (Abeta40\\/Abeta42), soluble APP isoforms, Abeta oligomers and beta-site APP-cleaving enzyme 1 (BACE1). This article reviews recent research advances on core candidate CSF and plasma Abeta-related biomarkers, and gives a conceptual review on how to implement biomarkers in clinical trials in AD.

  14. A role for 12/15 lipoxygenase in the amyloid beta precursor protein metabolism.

    Science.gov (United States)

    Succol, Francesca; Praticò, Domenico

    2007-10-01

    12/15 Lipoxygenase (12/15LO) protein levels and activity are increased in pathologically affected regions of Alzheimer's disease (AD) brains, compared with controls. Its metabolic products are elevated in cerebrospinal fluid of patients with AD and individuals with mild cognitive impairment, suggesting that this enzyme may be involved early in AD pathogenesis. Herein, we investigate the effect of pharmacologic inhibition of 12/15LO on the amyloid beta precursor protein (APP) metabolism. To this end, we used CHO and N2A cells stably expressing human APP with the Swedish mutant, and two structurally distinct and selective 12/15LO inhibitors, PD146176 and CDC. Our results demonstrated that both drugs dose-dependently reduced Abeta formation without affecting total APP levels. Interestingly, in the same cells we observed a significant reduction in secreted (s)APPbeta and beta-secretase (BACE), but not sAPPalpha and ADAM10 protein levels. Together, these data show for the first time that this enzymatic pathway influences Abeta formation whereby modulating the BACE proteolytic cascade. We conclude that specific pharmacologic inhibition of 12/15LO could represent a novel therapeutic target for treating or preventing AD pathology in humans.

  15. Biological markers of amyloid beta-related mechanisms in Alzheimer's disease.

    LENUS (Irish Health Repository)

    Hampel, Harald

    2010-06-01

    Recent research progress has given detailed knowledge on the molecular pathogenesis of Alzheimer\\'s disease (AD), which has been translated into an intense, ongoing development of disease-modifying treatments. Most new drug candidates are targeted on inhibiting amyloid beta (Abeta) production and aggregation. In drug development, it is important to co-develop biomarkers for Abeta-related mechanisms to enable early diagnosis and patient stratification in clinical trials, and to serve as tools to identify and monitor the biochemical effect of the drug directly in patients. Biomarkers are also requested by regulatory authorities to serve as safety measurements. Molecular aberrations in the AD brain are reflected in the cerebrospinal fluid (CSF). Core CSF biomarkers include Abeta isoforms (Abeta40\\/Abeta42), soluble APP isoforms, Abeta oligomers and beta-site APP-cleaving enzyme 1 (BACE1). This article reviews recent research advances on core candidate CSF and plasma Abeta-related biomarkers, and gives a conceptual review on how to implement biomarkers in clinical trials in AD.

  16. Investigation of the inhibitory effects of TiO{sub 2} on the β-amyloid peptide aggregation

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Mukhtar H., E-mail: ahmed-m@email.ulster.ac.uk [School of Chemical Science, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland); Nanotechnology Integrated Bioengineering Centre, University of Ulster, Jordanstown, BT37 0QB Belfast (United Kingdom); Byrne, John A. [Nanotechnology Integrated Bioengineering Centre, University of Ulster, Jordanstown, BT37 0QB Belfast (United Kingdom); Keyes, Tia E. [School of Chemical Science, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland)

    2014-06-01

    TiO{sub 2} thin films are of great interest as biocompatible coatings and also as photocatalytic self-cleaning and antimicrobial coatings. In this work we used β-amyloid as a model for infectious protein to investigate the attachment and photocatalytic degradation. TiO{sub 2} films were prepared on stainless steel substrates using magnetron sputtering. The films were characterised before and after exposure to β-amyloid (1–42), using XRD, Raman spectroscopy, XPS and AFM. The TiO{sub 2} film was mostly composed of the anatase phase with a relatively high surface roughness. The presence of Raman peaks at 1668 cm{sup −1} and 1263 cm{sup −1}, with the XPS spectral feature for nitrogen at 400 eV, confirmed the adsorption of amyloid on surface. Following exposure of the β-amyloid contaminated TiO{sub 2} to UV-B irradiation a slight shift of amide modes was observed. Furthermore, the amide I spectra show an overall decrease in α-helix content with presence of a minor peak around 1591 cm{sup −1}, which is related to tryptophanyl and tyrosinyl radicals, which can lead to conformational change of β-amyloid. The C1s band at 292.2 eV suggests the formation of free carboxylic acid. The loss in the crucial structure of β-amyloid leads to reduce the fibril formation, thought to be induced through a photocatalytic process. - Highlights: • TiO{sub 2} thin films synthesised and characterised • Absorption study using β-amyloid (1–42) • Investigation of peptide configuration via Raman, AFM and XPS spectroscopies • β-Amyloid was subsequently degraded by photocatalytic activity of TiO{sub 2}.

  17. Mapping of the gene encoding the. beta. -amyloid precursor protein and its relationship to the Down syndrome region of chromosome 21

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, D.; Gardiner, K.; Kao, F.T.; Tanzi, R.; Watkins, P.; Gusella, J.F. (Eleanor Roosevelt Institute for Cancer Research, Denver, CO (USA))

    1988-11-01

    The gene encoding the {beta}-amyloid precursor protein has been assigned to human chromosome 21, as has a gene responsible for at least some cases of familial Alzheimer disease. Linkage studies strongly suggest that the {beta}-amyloid precursor protein and the product corresponding to familial Alzheimer disease are from two genes, or at least that several million base pairs of DNA separate the markers. The precise location of the {beta}-amyloid precursor protein gene on chromosome 21 has not yet been determined. Here the authors show, by using a somatic-cell/hybrid-cell mapping panel, in situ hybridization, and transverse-alternating-field electrophoresis, that the {beta}-amyloid precursor protein gene is located on chromosome 21 very near the 21q21/21q/22 border and probably within the region of chromosome 21 that, when trisomic, results in Down syndrome.

  18. Vascular remodeling versus amyloid beta-induced oxidative stress in the cerebrovascular dysfunctions associated with Alzheimer's disease.

    Science.gov (United States)

    Tong, Xin-Kang; Nicolakakis, Nektaria; Kocharyan, Ara; Hamel, Edith

    2005-11-30

    The roles of oxidative stress and structural alterations in the cerebrovascular dysfunctions associated with Alzheimer's disease (AD) were investigated in transgenic mice overexpressing amyloid precusor protein (APP+) or transforming growth factor-beta1 (TGF+). Age-related impairments and their in vitro reversibility were evaluated, and underlying pathogenic mechanisms were assessed and compared with those seen in AD brains. Vasoconstrictions to 5-HT and endothelin-1 were preserved, except in the oldest (18-21 months of age) TGF+ mice. Despite unaltered relaxations to sodium nitroprusside, acetylcholine (ACh) and calcitonin gene-related peptide-mediated dilatations were impaired, and there was an age-related deficit in the basal availability of nitric oxide (NO) that progressed more gradually in TGF+ mice. The expression and progression of these deficits were unrelated to the onset or extent of thioflavin-S-positive vessels. Manganese superoxide dismutase (SOD2) was upregulated in pial vessels and around brain microvessels of APP+ mice, pointing to a role of superoxide in the dysfunctions elicited by amyloidosis. In contrast, vascular wall remodeling associated with decreased levels of endothelial NO synthase and cyclooxygenase-2 and increased contents of vascular endothelial growth factor and collagen-I and -IV characterized TGF+ mice. Exogenous SOD or catalase normalized ACh dilatations and NO availability in vessels from aged APP+ mice but had no effect in those of TGF+ mice. Increased perivascular oxidative stress was not evidenced in AD brains, but vascular wall alterations compared well with those seen in TGF+ mice. We conclude that brain vessel remodeling and associated alterations in levels of vasoactive signaling molecules are key contributors to AD cerebrovascular dysfunctions.

  19. The effect of resveratrol on beta amyloid-induced memory impairment involves inhibition of phosphodiesterase-4 related signaling.

    Science.gov (United States)

    Wang, Gang; Chen, Ling; Pan, Xiaoyu; Chen, Jiechun; Wang, Liqun; Wang, Weijie; Cheng, Ruochuan; Wu, Fan; Feng, Xiaoqing; Yu, Yingcong; Zhang, Han-Ting; O'Donnell, James M; Xu, Ying

    2016-04-05

    Resveratrol, a natural polyphenol found in red wine, has wide spectrum of pharmacological properties including antioxidative and antiaging activities. Beta amyloid peptides (Aβ) are known to involve cognitive impairment, neuroinflammatory and apoptotic processes in Alzheimer's disease (AD). Activation of cAMP and/or cGMP activities can improve memory performance and decrease the neuroinflammation and apoptosis. However, it remains unknown whether the memory enhancing effect of resveratrol on AD associated cognitive disorders is related to the inhibition of phosphodiesterase 4 (PDE4) subtypes and subsequent increases in intracellular cAMP and/or cGMP activities. This study investigated the effect of resveratrol on Aβ1-42-induced cognitive impairment and the participation of PDE4 subtypes related cAMP or cGMP signaling. Mice microinfused with Aβ1-42 into bilateral CA1 subregions displayed learning and memory impairment, as evidenced by reduced memory acquisition and retrieval in the water maze and retention in the passive avoidance tasks; it was also significant that neuroinflammatory and pro-apoptotic factors were increased in Aβ1-42-treated mice. Aβ1-42-treated mice also increased in PDE4A, 4B and 4D expression, and decreased in PKA level. However, PKA inhibitor H89, but not PKG inhibitor KT5823, prevented resveratrol's effects on these parameters. Resveratrol also reversed Aβ1-42-induced decreases in phosphorylated cAMP response-element binding protein (pCREB), brain derived neurotrophic factor (BDNF) and anti-apoptotic factor BCl-2 expression, which were reversed by H89. These findings suggest that resveratrol reversing Aβ-induced learning and memory disorder may involve the regulation of neuronal inflammation and apoptosis via PDE4 subtypes related cAMP-CREB-BDNF signaling.

  20. Satureja bachtiarica ameliorate beta-amyloid induced memory impairment, oxidative stress and cholinergic deficit in animal model of Alzheimer's disease.

    Science.gov (United States)

    Soodi, Maliheh; Saeidnia, Soodabeh; Sharifzadeh, Mohammad; Hajimehdipoor, Homa; Dashti, Abolfazl; Sepand, Mohammad Reza; Moradi, Shahla

    2016-04-01

    Extracellular deposition of Beta-amyloid peptide (Aβ) is the main finding in the pathophysiology of Alzheimer's disease (AD), which damages cholinergic neurons through oxidative stress and reduces the cholinergic neurotransmission. Satureja bachtiarica is a medicinal plant from the Lamiaceae family which was widely used in Iranian traditional medicine. The aim of the present study was to investigate possible protective effects of S. bachtiarica methanolic extract on Aβ induced spatial memory impairment in Morris Water Maze (MWM), oxidative stress and cholinergic neuron degeneration. Pre- aggregated Aβ was injected into the hippocampus of each rat bilaterally (10 μg/rat) and MWM task was performed 14 days later to evaluate learning and memory function. Methanolic extract of S.bachtiarica (10, 50 and 100 mg/Kg) was injected intraperitoneally for 19 consecutive days, after Aβ injection. After the probe test the brain tissue were collected and lipid peroxidation, Acetylcholinesterase (AChE) activity and Cholin Acetyl Transferees (ChAT) immunorectivity were measured in the hippocampus. Intrahipocampal injection of Aβ impaired learning and memory in MWM in training days and probe trail. Methanolic extract of S. bachtiarica (50 and 100 mg/Kg) could attenuate Aβ-induced memory deficit. ChAT immunostaining revealed that cholinergic neurons were loss in Aβ- injected group and S. bachtiarica (100 mg/Kg) could ameliorate Aβ- induced ChAT reduction in the hippocampus. Also S. bachtiarica could ameliorate Aβ-induced lipid peroxidation and AChE activity increase in the hippocampus. In conclusion our study represent that S.bachtiarica methanolic extract can improve Aβ-induced memory impairment and cholinergic loss then we recommended this extract as a candidate for further investigation in treatment of AD.

  1. Catalpol ameliorates beta amyloid-induced degeneration of cholinergic neurons by elevating brain-derived neurotrophic factors.

    Science.gov (United States)

    Wang, Z; Liu, Q; Zhang, R; Liu, S; Xia, Z; Hu, Y

    2009-11-10

    The purpose of this work is to study the effect of catalpol, an iridoid from Rehmannia glutinosa on neurodegenerative changes induced by beta-amyloid peptide Abeta(25-35) or Abeta(25-35)+ibotenic acid and the underlying mechanism. Results showed that catalpol significantly improved the memory deficits in the neurodegenerative mouse model produced by injection of Abeta(25-35)+ibotenic acid to the nucleus magnocellularis basalis, yet it is neither a cholinesterase inhibitor nor a muscarinic (M) receptor agonist. Instead, the choline acetyl transferase (ChAT) activity and the M receptor density in brain were significantly decreased in the model mice and catalpol could significantly elevate their levels. Furthermore, the brain-derived neurotrophic factor (BDNF) content in brain was significantly decreased in the model mice and catalpol elevated it to normal level (83%+/-3% and 102%+/-2% of normal respectively). There is a significant positive correlation between BDNF content and memory. Primary culture of forebrain neurons revealed that aggregated Abeta(25-35) induced significant decrease of ChAT positive neuron number, neurite outgrowth length, and M receptor density, while catalpol added to the culture medium 2 h prior to Abeta addition showed significant dose dependent protective effect. Notably, 24 h and 48 h after the addition of Abeta to the cultured cells, the BDNF mRNA level in the neurons decreased to 76%+/-7% and 66%+/-3% of control without catalpol treatment, but became 128%+/-17% and 131%+/-23% of control with catalpol treatment. When the action of BDNF was inhibited by k252a in the cultured neurons, the protective effect of catalpol was completely (neurite outgrowth length) or partially (ChAT positive neuron number and the M receptor density) abolished. Taken together, catalpol improves memory and protects the forebrain neurons from neurodegeneration through increasing BDNF expression. Whether catalpol could reverse the neurodegenerative changes already

  2. Electrochemical quantification of the Alzheimer’s disease amyloid-β (1–40 using amyloid-β fibrillization promoting peptide

    Directory of Open Access Journals (Sweden)

    Satoshi Fujii

    2015-12-01

    Full Text Available Amyloidpeptide (Aβ is believed to be an important biomarker for the early diagnosis of Alzheimer’s disease. Therefore, practical and reliable methods to assay Aβ levels have been coveted. In this study, a rapid, sensitive, and selective electrochemical method for Aβ(1–40 detection using Cu2+ redox cycling on peptide-modified gold electrodes was developed. A 19-residue peptide that can promote Aβ fibrillization (AFPP was immobilized onto a gold electrode. After incubating an Aβ solution with the modified electrode for 1 h, a Cu2+ solution was added and cyclic voltammetry measurements were conducted. The voltammetric response was found to be proportional to the Aβ(1–40 concentration in the 0.1–5 μM range, and a detection limit of 18 nM was achieved. Washing with sodium hydroxide and ethylenediaminetetraacetate solutions easily reinitialized the modified electrode. Results obtained using the reinitialized electrode showed good reproducibility. Furthermore, when another amyloidogenic and Cu2+-binding protein amylin was used as the target, no voltammetric response was observed. These results indicate that the AFPP-modified electrode provides a promising, label-free, sensitive, selective, cost-effective, and easy method for the quantification of Aβ. Keywords: Amyloid-β, Alzheimer’s disease (AD, Fibrillization, Electrochemical detection, Nanobiochip, Cu redox

  3. Adiponectin is protective against oxidative stress induced cytotoxicity in amyloid-beta neurotoxicity.

    Directory of Open Access Journals (Sweden)

    Koon-Ho Chan

    Full Text Available Beta-amyloid (Aβ neurotoxicity is important in Alzheimer's disease (AD pathogenesis. Aβ neurotoxicity causes oxidative stress, inflammation and mitochondrial damage resulting in neuronal degeneration and death. Oxidative stress, inflammation and mitochondrial failure are also pathophysiological mechanisms of type 2 diabetes (T(2DM which is characterized by insulin resistance. Interestingly, T(2DM increases risk to develop AD which is associated with reduced neuronal insulin sensitivity (central insulin resistance. We studied the potential protective effect of adiponectin (an adipokine with insulin-sensitizing, anti-inflammatory and anti-oxidant properties against Aβ neurotoxicity in human neuroblastoma cells (SH-SY5Y transfected with the Swedish amyloid precursor protein (Sw-APP mutant, which overproduced Aβ with abnormal intracellular Aβ accumulation. Cytotoxicity was measured by assay for lactate dehydrogenase (LDH released upon cell death and lysis. Our results revealed that Sw-APP transfected SH-SY5Y cells expressed both adiponectin receptor 1 and 2, and had increased AMP-activated protein kinase (AMPK activation and enhanced nuclear factor-kappa B (NF-κB activation compared to control empty-vector transfected SH-SY5Y cells. Importantly, adiponectin at physiological concentration of 10 µg/ml protected Sw-APP transfected SH-SY5Y cells against cytotoxicity under oxidative stress induced by hydrogen peroxide. This neuroprotective action of adiponectin against Aβ neurotoxicity-induced cytotoxicity under oxidative stress involved 1 AMPK activation mediated via the endosomal adaptor protein APPL1 (adaptor protein with phosphotyrosine binding, pleckstrin homology domains and leucine zipper motif and possibly 2 suppression of NF-κB activation. This raises the possibility of novel therapies for AD such as adiponectin receptor agonists.

  4. Natural Amyloid-Beta Oligomers Acutely Impair the Formation of a Contextual Fear Memory in Mice

    Science.gov (United States)

    Kittelberger, Kara A.; Piazza, Fabrizio; Tesco, Giuseppina; Reijmers, Leon G.

    2012-01-01

    Memory loss is one of the hallmark symptoms of Alzheimer's disease (AD). It has been proposed that soluble amyloid-beta (Abeta) oligomers acutely impair neuronal function and thereby memory. We here report that natural Abeta oligomers acutely impair contextual fear memory in mice. A natural Abeta oligomer solution containing Abeta monomers, dimers, trimers, and tetramers was derived from the conditioned medium of 7PA2 cells, a cell line that expresses human amyloid precursor protein containing the Val717Phe familial AD mutation. As a control we used 7PA2 conditioned medium from which Abeta oligomers were removed through immunodepletion. Separate groups of mice were injected with Abeta and control solutions through a cannula into the lateral brain ventricle, and subjected to fear conditioning using two tone-shock pairings. One day after fear conditioning, mice were tested for contextual fear memory and tone fear memory in separate retrieval trials. Three experiments were performed. For experiment 1, mice were injected three times: 1 hour before and 3 hours after fear conditioning, and 1 hour before context retrieval. For experiments 2 and 3, mice were injected a single time at 1 hour and 2 hours before fear conditioning respectively. In all three experiments there was no effect on tone fear memory. Injection of Abeta 1 hour before fear conditioning, but not 2 hours before fear conditioning, impaired the formation of a contextual fear memory. In future studies, the acute effect of natural Abeta oligomers on contextual fear memory can be used to identify potential mechanisms and treatments of AD associated memory loss. PMID:22238679

  5. Preventive immunization of aged and juvenile non-human primates to beta-amyloid

    Directory of Open Access Journals (Sweden)

    Kofler Julia

    2012-05-01

    Full Text Available Abstract Background Immunization against beta-amyloid (Aβ is a promising approach for the treatment of Alzheimer’s disease, but the optimal timing for the vaccination remains to be determined. Preventive immunization approaches may be more efficacious and associated with fewer side-effects; however, there is only limited information available from primate models about the effects of preclinical vaccination on brain amyloid composition and the neuroinflammatory milieu. Methods Ten non-human primates (NHP of advanced age (18–26 years and eight 2-year-old juvenile NHPs were immunized at 0, 2, 6, 10 and 14 weeks with aggregated Aβ42 admixed with monophosphoryl lipid A as adjuvant, and monitored for up to 6 months. Anti-Aβ antibody levels and immune activation markers were assessed in plasma and cerebrospinal fluid samples before and at several time-points after immunization. Microglial activity was determined by [11C]PK11195 PET scans acquired before and after immunization, and by post-mortem immunohistochemical and real-time PCR evaluation. Aβ oligomer composition was assessed by immunoblot analysis in the frontal cortex of aged immunized and non-immunized control animals. Results All juvenile animals developed a strong and sustained serum anti-Aβ IgG antibody response, whereas only 80 % of aged animals developed detectable antibodies. The immune response in aged monkeys was more delayed and significantly weaker, and was also more variable between animals. Pre- and post-immunization [11C]PK11195 PET scans showed no evidence of vaccine-related microglial activation. Post-mortem brain tissue analysis indicated a low overall amyloid burden, but revealed a significant shift in oligomer size with an increase in the dimer:pentamer ratio in aged immunized animals compared with non-immunized controls (P  Conclusions Our results indicate that preventive Aβ immunization is a safe therapeutic approach lacking adverse CNS immune system

  6. HIV-1 stimulates nuclear entry of amyloid beta via dynamin dependent EEA1 and TGF-β/Smad signaling

    International Nuclear Information System (INIS)

    András, Ibolya E.; Toborek, Michal

    2014-01-01

    Clinical evidence indicates increased amyloid deposition in HIV-1-infected brains, which contributes to neurocognitive dysfunction in infected patients. Here we show that HIV-1 exposure stimulates amyloid beta (Aβ) nuclear entry in human brain endothelial cells (HBMEC), the main component of the blood–brain barrier (BBB). Treatment with HIV-1 and/or Aβ resulted in concurrent increase in early endosomal antigen-1 (EEA1), Smad, and phosphorylated Smad (pSmad) in nuclear fraction of HBMEC. A series of inhibition and silencing studies indicated that Smad and EEA1 closely interact by influencing their own nuclear entry; the effect that was attenuated by dynasore, a blocker of GTP-ase activity of dynamin. Importantly, inhibition of dynamin, EEA1, or TGF-β/Smad effectively attenuated HIV-1-induced Aβ accumulation in the nuclei of HBMEC. The present study indicates that nuclear uptake of Aβ involves the dynamin-dependent EEA1 and TGF-β/Smad signaling pathways. These results identify potential novel targets to protect against HIV-1-associated dysregulation of amyloid processes at the BBB level. - Highlights: • HIV-1 induces nuclear accumulation of amyloid beta (Aβ) in brain endothelial cells. • EEA-1 and TGF-Β/Smad act in concert to regulate nuclear entry of Aβ. • Dynamin appropriates the EEA-1 and TGF-Β/Smad signaling. • Dynamin serves as a master regulator of HIV-1-induced nuclear accumulation of Aβ

  7. HIV-1 stimulates nuclear entry of amyloid beta via dynamin dependent EEA1 and TGF-β/Smad signaling

    Energy Technology Data Exchange (ETDEWEB)

    András, Ibolya E., E-mail: iandras@med.miami; Toborek, Michal, E-mail: mtoborek@med.miami.edu

    2014-04-15

    Clinical evidence indicates increased amyloid deposition in HIV-1-infected brains, which contributes to neurocognitive dysfunction in infected patients. Here we show that HIV-1 exposure stimulates amyloid beta (Aβ) nuclear entry in human brain endothelial cells (HBMEC), the main component of the blood–brain barrier (BBB). Treatment with HIV-1 and/or Aβ resulted in concurrent increase in early endosomal antigen-1 (EEA1), Smad, and phosphorylated Smad (pSmad) in nuclear fraction of HBMEC. A series of inhibition and silencing studies indicated that Smad and EEA1 closely interact by influencing their own nuclear entry; the effect that was attenuated by dynasore, a blocker of GTP-ase activity of dynamin. Importantly, inhibition of dynamin, EEA1, or TGF-β/Smad effectively attenuated HIV-1-induced Aβ accumulation in the nuclei of HBMEC. The present study indicates that nuclear uptake of Aβ involves the dynamin-dependent EEA1 and TGF-β/Smad signaling pathways. These results identify potential novel targets to protect against HIV-1-associated dysregulation of amyloid processes at the BBB level. - Highlights: • HIV-1 induces nuclear accumulation of amyloid beta (Aβ) in brain endothelial cells. • EEA-1 and TGF-Β/Smad act in concert to regulate nuclear entry of Aβ. • Dynamin appropriates the EEA-1 and TGF-Β/Smad signaling. • Dynamin serves as a master regulator of HIV-1-induced nuclear accumulation of Aβ.

  8. Peptides of presenilin-1 bind the amyloid precursor protein ectodomain and offer a novel and specific therapeutic approach to reduce ß-amyloid in Alzheimer's disease.

    Science.gov (United States)

    Dewji, Nazneen N; Singer, S Jonathan; Masliah, Eliezer; Rockenstein, Edward; Kim, Mihyun; Harber, Martha; Horwood, Taylor

    2015-01-01

    β-Amyloid (Aβ) accumulation in the brain is widely accepted to be critical to the development of Alzheimer's disease (AD). Current efforts at reducing toxic Aβ40 or 42 have largely focused on modulating γ-secretase activity to produce shorter, less toxic Aβ, while attempting to spare other secretase functions. In this paper we provide data that offer the potential for a new approach for the treatment of AD. The method is based on our previous findings that the production of Aβ from the interaction between the β-amyloid precursor protein (APP) and Presenilin (PS), as part of the γ-secretase complex, in cell culture is largely inhibited if the entire water-soluble NH2-terminal domain of PS is first added to the culture. Here we demonstrate that two small, non-overlapping water-soluble peptides from the PS-1 NH2-terminal domain can substantially and specifically inhibit the production of total Aβ as well as Aβ40 and 42 in vitro and in vivo in the brains of APP transgenic mice. These results suggest that the inhibitory activity of the entire amino terminal domain of PS-1 on Aβ production is largely focused in a few smaller sequences within that domain. Using biolayer interferometry and confocal microscopy we provide evidence that peptides effective in reducing Aβ give a strong, specific and biologically relevant binding with the purified ectodomain of APP 695. Finally, we demonstrate that the reduction of Aβ by the peptides does not affect the catalytic activities of β- or γ-secretase, or the level of APP. P4 and P8 are the first reported protein site-specific small peptides to reduce Aβ production in model systems of AD. These peptides and their derivatives offer new potential drug candidates for the treatment of AD.

  9. Peptides of presenilin-1 bind the amyloid precursor protein ectodomain and offer a novel and specific therapeutic approach to reduce ß-amyloid in Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Nazneen N Dewji

    Full Text Available β-Amyloid (Aβ accumulation in the brain is widely accepted to be critical to the development of Alzheimer's disease (AD. Current efforts at reducing toxic Aβ40 or 42 have largely focused on modulating γ-secretase activity to produce shorter, less toxic Aβ, while attempting to spare other secretase functions. In this paper we provide data that offer the potential for a new approach for the treatment of AD. The method is based on our previous findings that the production of Aβ from the interaction between the β-amyloid precursor protein (APP and Presenilin (PS, as part of the γ-secretase complex, in cell culture is largely inhibited if the entire water-soluble NH2-terminal domain of PS is first added to the culture. Here we demonstrate that two small, non-overlapping water-soluble peptides from the PS-1 NH2-terminal domain can substantially and specifically inhibit the production of total Aβ as well as Aβ40 and 42 in vitro and in vivo in the brains of APP transgenic mice. These results suggest that the inhibitory activity of the entire amino terminal domain of PS-1 on Aβ production is largely focused in a few smaller sequences within that domain. Using biolayer interferometry and confocal microscopy we provide evidence that peptides effective in reducing Aβ give a strong, specific and biologically relevant binding with the purified ectodomain of APP 695. Finally, we demonstrate that the reduction of Aβ by the peptides does not affect the catalytic activities of β- or γ-secretase, or the level of APP. P4 and P8 are the first reported protein site-specific small peptides to reduce Aβ production in model systems of AD. These peptides and their derivatives offer new potential drug candidates for the treatment of AD.

  10. Peptide design using alpha,beta-dehydro amino acids: from beta-turns to helical hairpins.

    Science.gov (United States)

    Mathur, Puniti; Ramakumar, S; Chauhan, V S

    2004-01-01

    Incorporation of alpha,beta-dehydrophenylalanine (DeltaPhe) residue in peptides induces folded conformations: beta-turns in short peptides and 3(10)-helices in larger ones. A few exceptions-namely, alpha-helix or flat beta-bend ribbon structures-have also been reported in a few cases. The most favorable conformation of DeltaPhe residues are (phi,psi) approximately (-60 degrees, -30 degrees ), (-60 degrees, 150 degrees ), (80 degrees, 0 degrees ) or their enantiomers. DeltaPhe is an achiral and planar residue. These features have been exploited in designing DeltaPhe zippers and helix-turn-helix motifs. DeltaPhe can be incorporated in both right and left-handed helices. In fact, consecutive occurrence of three or more DeltaPhe amino acids induce left-handed screw sense in peptides containing L-amino acids. Weak interactions involving the DeltaPhe residue play an important role in molecular association. The C--H.O==C hydrogen bond between the DeltaPhe side-chain and backbone carboxyl moiety, pi-pi stacking interactions between DeltaPhe side chains belonging to enantiomeric helices have shown to stabilize folding. The unusual capability of a DeltaPhe ring to form the hub of multicentered interactions namely, a donor in aromatic C--H.pi and C--H.O==C and an acceptor in a CH(3).pi interaction suggests its exploitation in introducing long-range interactions in the folding of supersecondary structures. Copyright 2004 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2004

  11. [Noopept improves the spatial memory and stimulates prefibrillar beta-amyloid(25-35) antibody production in mice].

    Science.gov (United States)

    Bobkova, N V; Gruden', M A; Samokhin, A N; Medvinskaia, N I; Morozova-Roch, L; Uudasheva, T A; Ostrovskaia, R U; Seredinin, S B

    2005-01-01

    The effects of the novel proline-containing nootropic and neuroprotective dipeptide noopept (GVS-111, N-phenylacetyl-L-prolylglycine ethyl ester) were studied on NMRI mice upon olfactory bulbectomy, which had been previously shown to imitate the main morphological and biochemical signs of Alzheimer's disease (AD). The spatial memory was assessed using the Morris (water maze) test; the immunological status was characterized by ELISA with antibodies to prefibrillar beta-amyloid(25-35), S100b protein, and protofilaments of equine lysozyme, which are the molecular factors involved in the pathogenesis of AD. The control (sham-operated) animals during the Morris test preferred a sector where the safety platform was placed during the learning session. Bulbectomized animals treated with saline failed to recognize this sector, while bulbectomized animals treated with noopept (0.01 mg/kg for 21 days) restored this predominance, thus demonstrating the improvement of the spatial memory. These animals also demonstrated an increase in the level of antibodies to beta-amyloid(25-35)--the effect, which was more pronounced in the sham-operated than in bulbectomized mice. The latter demonstrated a profound decrease of immunological reactivity in a large number of tests. Noopept, stimulating the production of antibodies to beta-amyloid(25-35), can attenuate the well-known neurotoxic effects of beta-amyloid. The obtained data on the mnemotropic and immunostimulant effects noopept are indicative of good prospects for the clinical usage of this drug in the therapy of patients with neurodegenerative diseases.

  12. The antigen-binding fragment of human gamma immunoglobulin prevents amyloid β-peptide folding into β-sheet to form oligomers

    Science.gov (United States)

    Valls-Comamala, Victòria; Guivernau, Biuse; Bonet, Jaume; Puig, Marta; Perálvarez-Marín, Alex; Palomer, Ernest; Fernàndez-Busquets, Xavier; Altafaj, Xavier; Tajes, Marta; Puig-Pijoan, Albert; Vicente, Rubén; Oliva, Baldomero; Muñoz, Francisco J.

    2017-01-01

    The amyloid beta-peptide (Aβ) plays a leading role in Alzheimer's disease (AD) physiopathology. Even though monomeric forms of Aβ are harmless to cells, Aβ can aggregate into β-sheet oligomers and fibrils, which are both neurotoxic. Therefore, one of the main therapeutic approaches to cure or delay AD onset and progression is targeting Aβ aggregation. In the present study, we show that a pool of human gamma immunoglobulins (IgG) protected cortical neurons from the challenge with Aβ oligomers, as assayed by MTT reduction, caspase-3 activation and cytoskeleton integrity. In addition, we report the inhibitory effect of IgG on Aβ aggregation, as shown by Thioflavin T assay, size exclusion chromatography and atomic force microscopy. Similar results were obtained with Palivizumab, a human anti-sincitial virus antibody. In order to dissect the important domains, we cleaved the pool of human IgG with papain to obtain Fab and Fc fragments. Using these cleaved fragments, we functionally identified Fab as the immunoglobulin fragment inhibiting Aβ aggregation, a result that was further confirmed by an in silico structural model. Interestingly, bioinformatic tools show a highly conserved structure able to bind amyloid in the Fab region. Overall, our data strongly support the inhibitory effect of human IgG on Aβ aggregation and its neuroprotective role. PMID:28467807

  13. Genetic Mechanisms of Coffee Extract Protection in a Caenorhabditis elegans Model of β-Amyloid Peptide Toxicity

    OpenAIRE

    Dostal, Vishantie; Roberts, Christine M.; Link, Christopher D.

    2010-01-01

    Epidemiological studies have reported that coffee and/or caffeine consumption may reduce Alzheimer's disease (AD) risk. We found that coffee extracts can similarly protect against β-amyloid peptide (Aβ) toxicity in a transgenic Caenorhabditis elegans Alzheimer's disease model. The primary protective component(s) in this model is not caffeine, although caffeine by itself can show moderate protection. Coffee exposure did not decrease Aβ transgene expression and did not need to be present during...

  14. Aluminum complexing enhances amyloid beta protein penetration of blood-brain barrier.

    Science.gov (United States)

    Banks, William A; Niehoff, Michael L; Drago, Denise; Zatta, Paolo

    2006-10-20

    A significant co-morbidity of Alzheimer's disease and cerebrovascular impairment suggests that cerebrovascular dysregulation is an important feature of dementia. Amyloid beta protein (Abeta), a relevant risk factor in Alzheimer's disease, has neurotoxic properties and is thought to play a critical role in the cognitive impairments. Previously, we demonstrated that the 42mer of Abeta (Abeta42) complexed with aluminum (Al-Abeta42) is much more cytotoxic than non-complexed Abeta42. The level of Abeta in the brain is a balance between synthesis, degradation, and fluxes across the blood-brain barrier (BBB). In the present paper, we determined whether complexing with aluminum affected the ability of radioactively iodinated Abeta to cross the in vivo BBB. We found that the rates of uptake of Al-Abeta42 and Abeta42 were similar, but that Al-Abeta42 was sequestered by brain endothelial cells much less than Abeta42 and so more readily entered the parenchymal space of the brain. Al-Abeta42 also had a longer half-life in blood and had increased permeation at the striatum and thalamus. Brain-to-blood transport was similar for Al-Abeta42 and Abeta42. In conclusion, complexing with aluminum affects some aspects of blood-to-brain permeability so that Al-Abeta42 would have more ready access to brain cells than Abeta42.

  15. Distinct prion-like strains of amyloid beta implicated in phenotypic diversity of Alzheimer's disease.

    Science.gov (United States)

    Cohen, Mark; Appleby, Brian; Safar, Jiri G

    2016-01-01

    Vast evidence on human prions demonstrates that variable disease phenotypes, rates of propagation, and targeting of distinct brain structures are determined by unique conformers (strains) of pathogenic prion protein (PrP(Sc)). Recent progress in the development of advanced biophysical tools that inventory structural characteristics of amyloid beta (Aβ) in the brain cortex of phenotypically diverse Alzheimer's disease (AD) patients, revealed unique spectrum of oligomeric particles in the cortex of rapidly progressive cases, implicating these structures in variable rates of propagation in the brain, and in distict disease manifestation. Since only ∼30% of phenotypic diversity of AD can be explained by polymorphisms in risk genes, these and transgenic bioassay data argue that structurally distinct Aβ particles play a major role in the diverse pathogenesis of AD, and may behave as distinct prion-like strains encoding diverse phenotypes. From these observations and our growing understanding of prions, there is a critical need for new strain-specific diagnostic strategies for misfolded proteins causing these elusive disorders. Since targeted drug therapy can induce mutation and evolution of prions into new strains, effective treatments of AD will require drugs that enhance clearance of pathogenic conformers, reduce the precursor protein, or inhibit the conversion of precursors into prion-like states.

  16. Amyloid-Beta Induced Changes in Vesicular Transport of BDNF in Hippocampal Neurons

    Directory of Open Access Journals (Sweden)

    Bianca Seifert

    2016-01-01

    Full Text Available The neurotrophin brain derived neurotrophic factor (BDNF is an important growth factor in the CNS. Deficits in transport of this secretory protein could underlie neurodegenerative diseases. Investigation of disease-related changes in BDNF transport might provide insights into the cellular mechanism underlying, for example, Alzheimer’s disease (AD. To analyze the role of BDNF transport in AD, live cell imaging of fluorescently labeled BDNF was performed in hippocampal neurons of different AD model systems. BDNF and APP colocalized with low incidence in vesicular structures. Anterograde as well as retrograde transport of BDNF vesicles was reduced and these effects were mediated by factors released from hippocampal neurons into the extracellular medium. Transport of BDNF was altered at a very early time point after onset of human APP expression or after acute amyloid-beta(1-42 treatment, while the activity-dependent release of BDNF remained unaffected. Taken together, extracellular cleavage products of APP induced rapid changes in anterograde and retrograde transport of BDNF-containing vesicles while release of BDNF was unaffected by transgenic expression of mutated APP. These early transport deficits might lead to permanently impaired brain functions in the adult brain.

  17. Uncaria rhynchophylla, a Chinese medicinal herb, has potent antiaggregation effects on Alzheimer's beta-amyloid proteins.

    Science.gov (United States)

    Fujiwara, Hironori; Iwasaki, Koh; Furukawa, Katsutoshi; Seki, Takashi; He, Mei; Maruyama, Masahiro; Tomita, Naoki; Kudo, Yukitsuka; Higuchi, Makoto; Saido, Takaomi C; Maeda, Sumihiro; Takashima, Akihiko; Hara, Masahiko; Ohizumi, Yasushi; Arai, Hiroyuki

    2006-08-01

    Because the deposition of beta-amyloid protein (Abeta) is a consistent pathological hallmark of Alzheimer's disease (AD) brains, inhibition of Abeta generation, prevention of Abeta fibril formation, or destabilization of preformed Abeta fibrils would be attractive therapeutic strategies for the treatment of AD. We examined the effects of several medicinal herbs used in traditional Chinese medical formulae on the formation and destabilization of Abeta fibrils by using the thioflavin T binding assay, atomic force microscopic imaging, and electrophoresis. Our study demonstrates that several of these herbs have potent inhibitory effects on fibril formation of both Abeta(1-40) and Abeta(1-42) in concentration-dependent manners; in particular, Uncaria rhynchophylla inhibited Abeta aggregation most intensively. Significant destabilization of preformed Abeta(1-40) and Abeta(1-42) fibrils was also induced by Uncaria rhynchophylla as well as some other herb extracts. Three-dimensional HPLC analysis indicated that the water extract of this herb contains several different chemical compounds, including oxindole and indol alkaloids, which have been regarded as neuroprotective. Our results suggest that Uncaria rhynchophylla has remarkably inhibitory effects on the regulation of Abeta fibrils, and we conclude that this medicinal herb could have the potency to be a novel therapeutic agent to prevent and/or cure AD.

  18. Bioassay-Guided Isolation of Neuroprotective Compounds from Uncaria rhynchophylla against Beta-Amyloid-Induced Neurotoxicity.

    Science.gov (United States)

    Xian, Yan-Fang; Lin, Zhi-Xiu; Mao, Qing-Qiu; Hu, Zhen; Zhao, Ming; Che, Chun-Tao; Ip, Siu-Po

    2012-01-01

    Uncaria rhynchophylla is a component herb of many Chinese herbal formulae for the treatment of neurodegenerative diseases. Previous study in our laboratory has demonstrated that an ethanol extract of Uncaria rhynchophylla ameliorated cognitive deficits in a mouse model of Alzheimer's disease induced by D-galactose. However, the active ingredients of Uncaria rhynchophylla responsible for the anti-Alzheimer's disease activity have not been identified. This study aims to identify the active ingredients of Uncaria rhynchophylla by a bioassay-guided fractionation approach and explore the acting mechanism of these active ingredients by using a well-established cellular model of Alzheimer's disease, beta-amyloid- (Aβ-) induced neurotoxicity in PC12 cells. The results showed that six alkaloids, namely, corynoxine, corynoxine B, corynoxeine, isorhynchophylline, isocorynoxeine, and rhynchophylline were isolated from the extract of Uncaria rhynchophylla. Among them, rhynchophylline and isorhynchophylline significantly decreased Aβ-induced cell death, intracellular calcium overloading, and tau protein hyperphosphorylation in PC12 cells. These results suggest that rhynchophylline and isorhynchophylline are the major active ingredients responsible for the protective action of Uncaria rhynchophylla against Aβ-induced neuronal toxicity, and their neuroprotective effect may be mediated, at least in part, by inhibiting intracellular calcium overloading and tau protein hyperphosphorylation.

  19. Bioassay-Guided Isolation of Neuroprotective Compounds from Uncaria rhynchophylla against Beta-Amyloid-Induced Neurotoxicity

    Directory of Open Access Journals (Sweden)

    Yan-Fang Xian

    2012-01-01

    Full Text Available Uncaria rhynchophylla is a component herb of many Chinese herbal formulae for the treatment of neurodegenerative diseases. Previous study in our laboratory has demonstrated that an ethanol extract of Uncaria rhynchophylla ameliorated cognitive deficits in a mouse model of Alzheimer’s disease induced by D-galactose. However, the active ingredients of Uncaria rhynchophylla responsible for the anti-Alzheimer’s disease activity have not been identified. This study aims to identify the active ingredients of Uncaria rhynchophylla by a bioassay-guided fractionation approach and explore the acting mechanism of these active ingredients by using a well-established cellular model of Alzheimer’s disease, beta-amyloid- (Aβ- induced neurotoxicity in PC12 cells. The results showed that six alkaloids, namely, corynoxine, corynoxine B, corynoxeine, isorhynchophylline, isocorynoxeine, and rhynchophylline were isolated from the extract of Uncaria rhynchophylla. Among them, rhynchophylline and isorhynchophylline significantly decreased Aβ-induced cell death, intracellular calcium overloading, and tau protein hyperphosphorylation in PC12 cells. These results suggest that rhynchophylline and isorhynchophylline are the major active ingredients responsible for the protective action of Uncaria rhynchophylla against Aβ-induced neuronal toxicity, and their neuroprotective effect may be mediated, at least in part, by inhibiting intracellular calcium overloading and tau protein hyperphosphorylation.

  20. Gray matter network disruptions and amyloid beta in cognitively normal adults.

    Science.gov (United States)

    Tijms, Betty M; Kate, Mara Ten; Wink, Alle Meije; Visser, Pieter Jelle; Ecay, Mirian; Clerigue, Montserrat; Estanga, Ainara; Garcia Sebastian, Maite; Izagirre, Andrea; Villanua, Jorge; Martinez Lage, Pablo; van der Flier, Wiesje M; Scheltens, Philip; Sanz Arigita, Ernesto; Barkhof, Frederik

    2016-01-01

    Gray matter networks are disrupted in Alzheimer's disease (AD). It is unclear when these disruptions start during the development of AD. Amyloid beta 1-42 (Aβ42) is among the earliest changes in AD. We studied, in cognitively healthy adults, the relationship between Aβ42 levels in cerebrospinal fluid (CSF) and single-subject cortical gray matter network measures. Single-subject gray matter networks were extracted from structural magnetic resonance imaging scans in a sample of cognitively healthy adults (N = 185; age range 39-79, mini-mental state examination >25, N = 12 showed abnormal Aβ42 level and for 90 anatomical areas. Associations between continuous Aβ42 CSF levels and single-subject cortical gray matter network measures were tested. Smoothing splines were used to determine whether a linear or nonlinear relationship gave a better fit to the data. Lower Aβ42 CSF levels were linearly associated at whole brain level with lower connectivity density, and nonlinearly with lower clustering values and higher path length values, which is indicative of a less-efficient network organization. These relationships were specific to medial temporal areas, precuneus, and the middle frontal gyrus (all p levels can be related to gray matter networks disruptions. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Cellular demise and inflammatory microglial activation during beta-amyloid toxicity are governed by Wnt1 and canonical signaling pathways.

    Science.gov (United States)

    Chong, Zhao Zhong; Li, Faqi; Maiese, Kenneth

    2007-06-01

    Initially described as a modulator of embryogenesis for a number of organ systems, Wnt1 has recently been linked to the development of several neurodegenerative disorders, none being of greater significance than Alzheimer's disease. We therefore examined the ability of Wnt1 to oversee vital pathways responsible for cell survival during beta-amyloid (Abeta1-42) exposure. Here we show that Wnt1 is critical for protection in the SH-SY5Y neuronal cell line against genomic DNA degradation, membrane phosphatidylserine (PS) exposure, and microglial activation, since these neuroprotective attributes of Wnt1 are lost during gene silencing of Wnt1 protein expression. Intimately tied to Wnt1 protection is the presence and activation of Akt1. Pharmacological inhibition of the PI 3-K pathway or gene silencing of Akt1 expression can abrogate the protective capacity of Wnt1. Closely aligned with Wnt1 and Akt1 are the integrated canonical pathways of synthase kinase-3beta (GSK-3beta) and beta-catenin. Through Akt1 dependent pathways, Wnt1 phosphorylates GSK-3beta and maintains beta-catenin integrity to insure its translocation from the cytoplasm to the nucleus to block apoptosis. Our work outlines a highly novel role for Wnt1 and its integration with Akt1, GSK-3beta, and beta-catenin to foster neuronal cell survival and repress inflammatory microglial activation that can identify new avenues of therapy against neurodegenerative disorders.

  2. Rationally Designed Peptides and Peptidomimetics as Inhibitors of Amyloid-β (Aβ) Aggregation: Potential Therapeutics of Alzheimer's Disease.

    Science.gov (United States)

    Goyal, Deepti; Shuaib, Suniba; Mann, Sukhmani; Goyal, Bhupesh

    2017-02-13

    Alzheimer's disease (AD) is a progressive neurodegenerative disease with no clinically accepted treatment to cure or halt its progression. The worldwide effort to develop peptide-based inhibitors of amyloid-β (Aβ) aggregation can be considered an unplanned combinatorial experiment. An understanding of what has been done and achieved may advance our understanding of AD pathology and the discovery of effective therapeutic agents. We review here the history of such peptide-based inhibitors, including those based on the Aβ sequence and those not derived from that sequence, containing both natural and unnatural amino acid building blocks. Peptide-based aggregation inhibitors hold significant promise for future AD therapy owing to their high selectivity, effectiveness, low toxicity, good tolerance, low accumulation in tissues, high chemical and biological diversity, possibility of rational design, and highly developed methods for analyzing their mode of action, proteolytic stability (modified peptides), and blood-brain barrier (BBB) permeability.

  3. Structure activity relationship study of curcumin analogues toward the amyloid-beta aggregation inhibitor.

    Science.gov (United States)

    Endo, Hitoshi; Nikaido, Yuri; Nakadate, Mamiko; Ise, Satomi; Konno, Hiroyuki

    2014-12-15

    Inhibition of the amyloid β aggregation process could possibly prevent the onset of Alzheimer's disease. In this article, we report a structure-activity relationship study of curcumin analogues for anti amyloid β aggregation activity. Compound 7, the ideal amyloid β aggregation inhibitor in vitro among synthesized curcumin analogues, has not only potent anti amyloid β aggregation effects, but also water solubility more than 160 times that of curcumin. In addition, new approaches to improve water solubility of curcumin-type compounds are proposed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. A carrier for non-covalent delivery of functional beta-galactosidase and antibodies against amyloid plaques and IgM to the brain.

    Directory of Open Access Journals (Sweden)

    Gobinda Sarkar

    Full Text Available BACKGROUND: Therapeutic intervention of numerous brain-associated disorders currently remains unrealized due to serious limitations imposed by the blood-brain-barrier (BBB. The BBB generally allows transport of small molecules, typically <600 daltons with high octanol/water partition coefficients, but denies passage to most larger molecules. However, some receptors present on the BBB allow passage of cognate proteins to the brain. Utilizing such receptor-ligand systems, several investigators have developed methods for delivering proteins to the brain, a critical requirement of which involves covalent linking of the target protein to a carrier entity. Such covalent modifications involve extensive preparative and post-preparative chemistry that poses daunting limitations in the context of delivery to any organ. Here, we report creation of a 36-amino acid peptide transporter, which can transport a protein to the brain after routine intravenous injection of the transporter-protein mixture. No covalent linkage of the protein with the transporter is necessary. APPROACH: A peptide transporter comprising sixteen lysine residues and 20 amino acids corresponding to the LDLR-binding domain of apolipoprotein E (ApoE was synthesized. Transport of beta-galactosidase, IgG, IgM, and antibodies against amyloid plques to the brain upon iv injection of the protein-transporter mixture was evaluated through staining for enzyme activity or micro single photon emission tomography (micro-SPECT or immunostaining. Effect of the transporter on the integrity of the BBB was also investigated. PRINCIPAL FINDINGS: The transporter enabled delivery to the mouse brain of functional beta-galactosidase, human IgG and IgM, and two antibodies that labeled brain-associated amyloid beta plaques in a mouse model of Alzheimer's disease. SIGNIFICANCE: The results suggest the transporter is able to transport most or all proteins to the brain without the need for chemically linking the

  5. Identification of Small Peptides in Human Cerebrospinal Fluid upon Amyloid-β Degradation.

    Science.gov (United States)

    Mizuta, Naoki; Yanagida, Kanta; Kodama, Takashi; Tomonaga, Takeshi; Takami, Mako; Oyama, Hiroshi; Kudo, Takashi; Ikeda, Manabu; Takeda, Masatoshi; Tagami, Shinji; Okochi, Masayasu

    2017-01-01

    Amyloid-β (Aβ) degradation in brains of Alzheimer disease patients is a crucial focus for the clarification of disease pathogenesis. Nevertheless, the mechanisms underlying Aβ degradation in the human brain remain unclear. This study aimed to quantify the levels of small C-terminal Aβ fragments generated upon Aβ degradation in human cerebrospinal fluid (CSF). A fraction containing small peptides was isolated and purified from human CSF by high-pressure liquid chromatography. Degradation products of Aβ C termini were identified and measured by liquid chromatography-tandem mass spectrometry. The C-terminal fragments of Aβ in the conditioned medium of cultured cells transfected with the Swedish variant of βAPP (sw βAPP) were analyzed. These fragments in brains of PS1 I213T knock-in transgenic mice, overexpressing sw βAPP, were also analyzed. The peptide fragments GGVV and GVV, produced by the cleavage of Aβ40, were identified in human CSF as well as in the brains of the transgenic mice and in the conditioned medium of the cultured cells. Relative to Aβ40 levels, GGVV and GVV levels were 7.6 ± 0.81 and 1.5 ± 0.18%, respectively, in human CSF. Levels of the GGVV fragment did not increase by the introduction of genes encoding neprilysin and insulin-degrading enzyme to the cultured cells. Our results indicate that a substantial amount of Aβ40 in human brains is degraded via a neprilysin- or insulin-degrading enzyme-independent pathway. © 2017 S. Karger AG, Basel.

  6. Cartilage acidic protein 1, a new member of the beta-propeller protein family with amyloid propensity.

    Science.gov (United States)

    Anjos, Liliana; Morgado, Isabel; Guerreiro, Marta; Cardoso, João C R; Melo, Eduardo P; Power, Deborah M

    2017-02-01

    Cartilage acidic protein1 (CRTAC1) is an extracellular matrix protein of chondrogenic tissue in humans and its presence in bacteria indicate it is of ancient origin. Structural modeling of piscine CRTAC1 reveals it belongs to the large family of beta-propeller proteins that in mammals have been associated with diseases, including amyloid diseases such as Alzheimer's. In order to characterize the structure/function evolution of this new member of the beta-propeller family we exploited the unique characteristics of piscine duplicate genes Crtac1a and Crtac1b and compared their structural and biochemical modifications with human recombinant CRTAC1. We demonstrate that CRTAC1 has a beta-propeller structure that has been conserved during evolution and easily forms high molecular weight thermo-stable aggregates. We reveal for the first time the propensity of CRTAC1 to form amyloid-like structures, and hypothesize that the aggregating property of CRTAC1 may be related to its disease-association. We further contribute to the general understating of CRTAC1's and beta-propeller family evolution and function. Proteins 2017; 85:242-255. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  7. The Alzheimer's Disease-Associated Amyloid β-Protein Is an Antimicrobial Peptide

    Science.gov (United States)

    Soscia, Stephanie J.; Kirby, James E.; Washicosky, Kevin J.; Tucker, Stephanie M.; Ingelsson, Martin; Hyman, Bradley; Burton, Mark A.; Goldstein, Lee E.; Duong, Scott; Tanzi, Rudolph E.; Moir, Robert D.

    2010-01-01

    Background The amyloid β-protein (Aβ) is believed to be the key mediator of Alzheimer's disease (AD) pathology. Aβ is most often characterized as an incidental catabolic byproduct that lacks a normal physiological role. However, Aβ 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 Aβ as an antimicrobial peptide (AMP). Experiments used established in vitro assays to compare antimicrobial activities of Aβ and LL-37, an archetypical human AMP. Findings reveal that Aβ 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 Aβ levels. Consistent with Aβ-mediated activity, the increased antimicrobial action was ablated by immunodepletion of AD brain homogenates with anti-Aβ antibodies. Conclusions/Significance Our findings suggest Aβ is a hitherto unrecognized AMP that may normally function in the innate immune system. This finding stands in stark contrast to current models of Aβ-mediated pathology and has important implications for ongoing and future AD treatment strategies. PMID:20209079

  8. The Physiological Roles of AmyloidPeptide Hint at New Ways to Treat Alzheimer's Disease

    Directory of Open Access Journals (Sweden)

    Holly M. Brothers

    2018-04-01

    Full Text Available Amyloid-ß (Aß is best known as the misfolded peptide that is involved in the pathogenesis of Alzheimer's disease (AD, and it is currently the primary therapeutic target in attempts to arrest the course of this disease. This notoriety has overshadowed evidence that Aß serves several important physiological functions. Aß is present throughout the lifespan, it has been found in all vertebrates examined thus far, and its molecular sequence shows a high degree of conservation. These features are typical of a factor that contributes significantly to biological fitness, and this suggestion has been supported by evidence of functions that are beneficial for the brain. The putative roles of Aß include protecting the body from infections, repairing leaks in the blood-brain barrier, promoting recovery from injury, and regulating synaptic function. Evidence for these beneficial roles comes from in vitro and in vivo studies, which have shown that the cellular production of Aß rapidly increases in response to a physiological challenge and often diminishes upon recovery. These roles are further supported by the adverse outcomes of clinical trials that have attempted to deplete Aß in order to treat AD. We suggest that anti-Aß therapies will produce fewer adverse effects if the known triggers of Aß deposition (e.g., pathogens, hypertension, and diabetes are addressed first.

  9. Viscoelastic response of neural cells governed by the deposition of amyloidpeptides (Aβ)

    Science.gov (United States)

    Gong, Ze; You, Ran; Chang, Raymond Chuen-Chung; Lin, Yuan

    2016-06-01

    Because of its intimate relation with Alzheimer's disease (AD), the question of how amyloidpeptide (Aβ) deposition alters the membrane and cytoskeltal structure of neural cells and eventually their mechanical response has received great attention. In this study, the viscoelastic properties of primary neurons subjected to various Aβ treatments were systematically characterized using atomic force microrheology. It was found that both the storage ( G ') and loss ( G ″) moduli of neural cells are rate-dependent and grow by orders of magnitude as the driving frequency ω varies from 1 to 100 Hz. However, a much stronger frequency dependence was observed in the loss moduli (with a scaling exponent of ˜0.96) than that in G ' ( ˜ ω 0.2 ). Furthermore, both cell moduli increase gradually within the first 6 h of Aβ treatment before steady-state values are reached, with a higher dosage of Aβ leading to larger changes in cell properties. Interestingly, we showed that the measured neuron response can be well-explained by a power law structural damping model. Findings here establish a quantitative link between Aβ accumulation and the physical characteristics of neural cells and hence could provide new insights into how disorders like AD affect the progression of different neurological processes from a mechanics point of view.

  10. 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

  11. Spatial patterns of brain amyloid-beta burden and atrophy rate associations in mild cognitive impairment

    NARCIS (Netherlands)

    Tosun, Duygu; Schuff, Norbert; Mathis, Chester A.; Jagust, William; Weiner, Michael W.; Saradha, A.; Abdi, Herve; Abdulkadir, Ahmed; Abeliovich, Asa; Abellan van Kan, Gabor; Abner, Erin; Acharya, Deepa; Agrusti, Antonella; Agyemang, Alex; Ahdidan, Jamila; Ahmed, Shiek; Ahn, Jae Eun; Aisen, Paul; Aksu, Yaman; Al-Akhras, Mousa; Alarcon, Marcelo; Alberca, Roman; Alexander, Gene; Alexander, Daniel; Alin, Aylin; Almeida, Fabio; Amlien, Inge; Anand, Shyam; Anderson, Dallas; Andrew, Marilee; Angersbach, Steve; Anjum, Ayesha; Aoyama, Eiji; Arfanakis, Konstantinos; Armor, Tom; Arnold, Steven; Arunagiri, Vidhya; Asatryan, Albert; Ashe-McNalley, Cody; Ashiga, Hirokazu; Assareh, Arezoo; Le Page, Aurelie; Avants, Brian; Avinash, Gopal; Aviv, Richard; Awasthi, Sukrati; Ayan-Oshodi, Mosun; Babic, Tomislav; Baek, Young; Bagci, Ulas; Bai, Shuyang; Baird, Geoffrey; Baker, John; Banks, Sarah; Bard, Jonathan; Barnes, Josephine; Bartlett, Jonathan; Bartzokis, George; Barua, Neil; Bauer, Corinna; Bayley, Peter; Beck, Irene; Becker, James; Becker, J. Alex; Beckett, Laurel; Bednar, Martin; Beg, Mirza Faisal; Bek, Stephan; Belaroussi, Boubakeur; Belmokhtar, Nabil; Bernard, Charlotte; Bertram, Lars; Bhaskar, Uday; Biffi, Alessandro; Bigler, Erin; Bilgic, Basar; Bishop, Courtney; Bittner, Daniel; Black, Ronald; Bogorodzki, Piotr; Bokde, Arun; Bonner-Jackson, Aaron; Boppana, Madhu; Bourgeat, Pierrick; Bowes, Mike; Bowman, DuBois; Bowman, Gene; Braskie, Meredith; Braunewell, Karl; Breitner, Joihn; Bresell, Anders; Brewer, James; Brickman, Adam; Britschgi, Markus; Broadbent, Steve; Brogren, Jacob; Brooks, David; Browndyke, Jeffrey; Brunton, Simon; Buchert, Ralph; Buchsbaum, Monte; Buckley, Chris; Buerger, Katharina; Burger, Cyrill; Burnham, Samantha; Burns, Jeffrey; Burton, David; Butman, John; Cabeza, Rafael; Cairns, Nigel; Callhoff, Johanna; Calvini, Piero; Cantillon, Marc; Capella, Heraldo; Carbotti, Angela; Cardona-Sanclemente, Luis Eduardo; Carle, Adam; Carmasin, Jeremy; Carranza-Ath, Fredy; Casabianca, Jodi; Casanova, Ramon; Cash, David; Cedarbaum, Jesse; Cella, Massimo; Celsis, Pierre; Chanu, Pascal; Chao, Linda; Charil, Arnaud; Chemali, Zeina; Chen, Rong; Chen, Jake; Chen, Gennan; Chen, Wei; Chen, Kewei; Chen, Shuzhong; Chen, Minhua; Cheng, Wei-Chen; Cherkas, Yauheniya; Chertkow, Howard; Cheung, Charlton; Cheung, Vinci; Chiang, Gloria; Chiba, Koji; Chin, Simon; Chisholm, Jane; Cho, Youngsang; Choe, John; Choubey, Suresh; Chowbina, Sudhir; Christensen, Anette Luther; Clark, David; Clark, Chris; Clarkson, Matt; Clayton, David; Clunie, David; Coen, Michael; Coimbra, Alexandre; Compton, David; Coppola, Giovanni; Coulin, Samuel; Cover, Keith S.; Crane, Paul; Crans, Gerald; Croop, Robert; Crowther, Daniel; Crum, William; Cui, Yue; Curry, Charles; Curtis, Steven; Cutter, Gary; Daiello, Lori; Dake, Michael; Dale, Anders; Daliri, Mohammad Reza; Damato, Vito Domenico; Darby, Eveleen; Darkner, Sune; Davatzikos, Christos; Dave, Jay; David, Renaud; DavidPrakash, Bhaskaran; Davidson, Julie; de Bruijne, Marleen; de Meyer, Geert; de Nunzio, Giorgio; Decarli, Charles; Dechairo, Bryan; DeDuck, Kristina; Dehghan, Hossein; Dejkam, Arsalan; Delfino, Manuel; Della Rosa, Pasquale Anthony; Dellavedova, Luca; Delpassand, Ebrahim; Delrieu, Julien; DeOrchis, Vincent; Depy Carron, Delphine; deToledo-Morrell, Leyla; Devanand, Davangere; Devanarayan, Viswanath; DeVous, Michael; Diaz-Arrastia, Ramon; Bradford, Dickerson; Ding, Xiaobo; Dinov, Ivo; Dobson, Howard; Dodge, Hiroko; Donohue, Michael; Dore, Vincent; Dorflinger, Ernest; Dowling, Maritza; Duan, Xujun; Dubal, Dena; Duchesne, Simon; Duff, Kevin; Dukart, Jrgen; Durazzo, Timothy; Dykstra, Kevin; Earl, Nancy; Edula, Goutham; Ekin, Ahmet; Elcoroaristizabal, Xabier; Emahazion, Tesfai; Engelman, Corinne; Epstein, Noam; Erten-Lyons, Deniz; Eskildsen, Simon; Falcone, Guido; Fan, Lingzhong; Fan, Yong; Farahibozorg, Seyedehrezvan; Farb, Norman; Farnum, Michael; Farrer, Lindsay; Farzan, Ali; Faux, Noel; Feldman, Betsy; Feldman, Howard; Feldman, Susan; Fennema-Notestine, Christine; Fernandes, Michel; Fernandez, Elsa; Ferrarini, Luca; Ferreira, Manuel Joao; Ferrer, Eugene; Figurski, Michal; Filipovych, Roman; Fillit, Howard; Finch, Stephen; Finlay, Daniel; Fiot, Jean-Baptiste; Flenniken, Derek; Fletcher, P. Thomas; Fletcher, Evan; Flynn Longmire, Crystal; Focke, Niels; Forman, Mark; Forsythe, Alan; Fox, Steven; Fox-Bosetti, Sabrina; Francis, Alexander L.; Franco-Villalobos, Conrado; Franko, Edit; Freeman, Stefanie; Friedrich, Christoph M.; Friesenhahn, Michel; Frings, Lars; Frisoni, Giovanni; Fritzsche, Klaus; Fujimoto, Yoko; Fujiwara, Ken; Fullerton, Terence; Furney, Simon; Gallins, Paul; Galvin, Ben; Gamst, Anthony; Gan, Ke; Garcia, Maria Teresa; Garg, Gaurav; Gaser, Christian; Gastineau, Edward; Gauthier, Serge; Gavett, Brandon; Gavidia, Giovana; Gazdzinski, Stefan; Ge, Qi; Ge, Tian; Gemme, Gianluca; Geraci, Joseph; Ghassabi, Zeinab; Gieschke, Ronald; Gil, Juan E.; Gill, Ryan; Gitelman, Darren; Gleason, Carey; Glymour, M. Maria; Godbey, Michael; Goghari, Vina; Gold, Michael; Goldberg, Terry; Goldman, Jennifer; Gomeni, Roberto; Gong, Shangwenyan; Gonzales, Celedon; Goodro, Robert; Gordon, Brian; Gore, Chris; Gorriz, Juan Manuel; Grachev, Igor; Grandey, Emily; Grasela, Thaddeus; Gratt, Jeremy; Gray, Katherine; Greenberg, Barry; Gregg, Keith; Gregory, Erik; Greicius, Michael; Greve, Douglas; Grill, Joshua; Gross, Alden; Gross, Alan; Guignot, Isabelle; Guo, Jeffrey; Guo, Qimiao; Guo, Hongbin; Guo, Lianghao; Habeck, Christian; Hai, Yizhen; Haight, Thaddeus; Hammarstrom, Per; Hampel, Harald; Han, Duke; Han, Jian; Han, Tony; Hanif, Muhammad; Hanna, Yousef; Hardy, Peter; Harvey, Danielle; Hasan, Md Kamrul; Hayashi, Toshihiro; Hazart, Aurelien; He, Huiguang; He, Yong; Head, Denise; Heckemann, Rolf; Heidebrink, Judith; Henderson, David; Henrard, Sebastien; Herholz, Karl; Hernandez, Monica; Herskovits, A. Zara; Hess, Christopher; Hildenbrand, Maike; Hobart, Jeremy; Hoffman, John; Holder, Daniel; Hollingworth, Paul; Holmes, Robin; Honigberg, Lee; Hoppin, Jack; Hou, Yangyang; Hsu, Ailing; Hsu, Wei-Wen; Hu, Xiaolan; Hu, Zhiwei; Hu, William; Huang, Juebin; Huang, Chien-Chih; Huang, Chingwen; Huang, Shuai; Huang, Yifan; Huang, Fude; Huang, Chun-Jung; Huang, Shu-Pang; Hubbard, Rebecca; Huentelman, Matthew; Hui, Shen; Huppertz, Hans-Jürgen; Hurko, Orest; Hurt, Stephen; Huyck, Susan; Hwang, Scott; Hyun, JungMoon; Ifeachor, Emmanuel; Iglesias, Martina; Ikari, Yasuhiko; Ikonomidou, Vasiliki; Imani, Farzin; Immermann, Fred; Inlow, Mark; Inoue, Lurdes; Insel, Philip; Irizarry, Michael; Irungu, Benson mwangi; Ishibashi, Taro; Ishii, Kenji; Ismail, Sara; Ismail, Shahina; Ito, Kaori; Iturria-Medina, Yasser; Iwatsubo, Takeshi; Jacobson, Mark; Jacqmin, Philippe; Jafari, Aria; Jafari-Khouzani, Kourosh; Jaffe, Carl; Jara, Hernan; Jasperse, Bas; Jedynak, Bruno; Jefferson, Angela; Jennings, J. Richard; Jessen, Walter; Jia, Fucang; Jiang, Tianzi; Jing, Huang; Johnson, Julene; Johnson, Sterling; Johnson, David K.; Jones, Richard; Juengling, Freimut; Juh, Rahyeong; Julin, Per; Kadish, Bill; Kahle-Wrobleski, Kristin; Kallam, Hanimi Reddy; Kamboh, M. Ilyas; Kaneko, Tomoki; Kaneta, Tomohiro; Kang, Ju Hee; Karageorgiou, Elissaios; Karantzoulis, Stella; Karlawish, Jason; Katz, Elyse; Kaushik, Sandeep S.; Kauwe, John; Kawakami, Hirofumi; Kazimipoor, Borhan; Kelleher, Thomas; Kennedy, Richard; Kerchner, Geoffrey; Kerrouche, Nacer; Khalil, Iya; Khalil, Andre; Killeen, Neil; Killiany, Ron; Kim, Jong Hun; Kim, Heeyoung; Kim, Ana; Kim, Yeonhee; Kim, Hyoungkyu; Kim, Seongkyun; Kim, Hyewon; Kimberg, Daniel; Kimura, Tokunori; King, Richard; Kirby, Justin; Kirsch, Wolff; Klimas, Michael; Kline, Richard; Kling, Mitchel; Klopfenstein, Erin; Koikkalainen, Juha; Kokomoor, Anders; Kolasny, Anthony; Koppel, Jeremy; Korolev, Igor; Kotran, Nickolas; Kouassi, Alex; Kowalczyk, Adam; Kozma, Lynn; Krams, Michael; Kratzer, Martina; Kuceyeski, Amy; Kuhn, Felix Pierre; Kumar, Sreedhar; Kuo, Hsun Ting; Kuo, Julie; Kurosawa, Ken; Kwon, Oh Hun; Labrish, Catherine; Laforet, Genevieve; Lai, Song; Lakatos, Anita; Lam, On Ki; Lampron, Antoine; Landau, Susan; Landen, Jaren; Lane, Richard; Langbaum, Jessica; Langford, Dianne; Lanius, Vivian; Laxamana, Joel; Le, Trung; Leahy, Richard; Lee, Jong-Min; Lee, Vita; Lee, Joseph H.; Lee, Grace; Lee, Dongsoo; Lee, Noah; Lefkimmiatis, Stamatis; Lemaitre, Herve; Lenfant, Pierre; Lenz, Robert; Leoutsakos, Jeannie-Marie; Lester, Gayle; Levey, Allan; Li, Shi-jiang; Li, Shanshan; Li, Wenjun; Li, Chin-Shang; Li, Xiaodong; Li, Rui; Li, Ming; Li, Lexin; Li, Jinhe; Li, Yi; Li, Quanzheng; Li, Gang; Liang, Kuchang; Liang, Peipeng; Liang, Lichen; Liao, Yuan-Lin; Lin, Ling-chih; Lin, Lan; Lin, Mingkuan; Lin, Ai-Ling; Liu, Songling; Liu, Yuan; Liu, Tianming; Liu, Meijie; Liu, Xiuwen; Liu, Li; Liu, Honggang; Liu, Pu; Liu, Tao; Liu, Sophia; Liu, Dazhong; Lo, Raymond; Lobanov, Victor; Loewenstein, David; Logovinsky, Veronika; Long, Xiaojing; Long, Ziyi; Looi, Jeffrey; Lu, Po-Haong; Lukic, Ana; Lull, Juan J.; Luo, Xiongjian; Lynch, John; Ma, Lei; Mackin, Scott; Mada, Marius; Magda, Sebastian; Maglio, Silvio; Maikusa, Norihide; Mak, Henry Ka-Fung; Malave, Vicente; Maldjian, Joseph; Mandal, Pravat; Mangin, Jean-Francois; Manjon, Jose; Mantri, Ninad; Manzour, Amir; Marambaud, Philippe; Marchewka, Artur; Marek, Kenneth; Markind, Samuel; Marshall, Gad; Martinez Torteya, Antonio; Mather, Mara; Mathis, Chester; Matoug, Sofia; Matsuo, Yoshiyuki; Mattei, Peter; Matthews, Dawn; McArdle, John; McCarroll, Steven; McEvoy, Linda; McGeown, William; McGonigle, John; McIntyre, John; McLaren, Donald; McQuail, Joseph; Meadowcroft, Mark; Meda, Shashwath; Mehta, Nirav; Melie-Garcia, Lester; Melrose, Rebecca; Mendonca, Brian; Menendez, Manuel; Meredith, Jere; Merrill, David; Mesulam, Marek-Marsel; Metti, Andrea; Meyer, Carsten; Mez, Jesse; Mickael, Guedj; Miftahof, Roustem; Mikhno, Arthur; Miller, David; Millikin, Colleen; Min, Ye; Mirza, Mubeena; Mistridis, Panagiota; Mitchell, Meghan; Mitsis, Effie; Mohan, Ananth; Moore, Dana; Moradi Birgani, Parmida; Moratal, David; Morimoto, Bruce; Mormino, Elizabeth; Mortamet, Benedicte; Moscato, Pablo; Mueller, Kathyrne; Mueller, Susanne; Mueller, Notger; Mukherjee, Shubhabrata; Mulder, Emma; Murayama, Shigeo; Murphy, Michael; Murray, Brian; Musiek, Erik; Myers, Amanda; Najafi, Shahla; Nazarparvar, Babak; Nazeri, Arash; Nettiksimmons, Jasmine; Neu, Scott; Ng, Yen-Bee; Nguyen, Nghi; Nguyen Xuan, Tuong; Nichols, Thomas; Nicodemus, Kristin; Niecko, Timothy; Nielsen, Casper; Notomi, Keiji; Nutakki, Gopi Chand; O'Bryant, Sid; O'Neil, Alison; Obisesan, Thomas; Oh, Dong Hoon; Oh, Joonmi; Okonkwo, Ozioma; Olde Rikkert, Marcel; Olmos, Salvador; Ortner, Marion; Ostrowitzki, Susanne; Oswald, Annahita; Ott, Brian; Ourselin, Sebastien; Ouyang, Gaoxiang; Paiva, Renata; Pan, Zhifang; Pande, Yogesh; Pardo, Jose; Pardoe, Heath; Park, Hyunjin; Park, Lovingly; Park, Moon Ho; Park, Sang hyun; Park, Kee Hyung; Park, Sujin; Parsey, Ramin; Parveen, Riswana; Paskavitz, James; Patel, Yogen; Patil, Manasi; Pawlak, Mikolaj; Payoux, Pierre; Pearson, Jim; Peavy, Guerry; Pell, Gaby; Peng, Yahong; Pennec, Xavier; Pepin, Jean louis; Perea, Rodrigo; Perneczky, Robert; Petitti, Diana; Petrella, Jeffrey; Peyrat, Jean-Marc; Pezoa, Jorge; Pham, Chi-Tuan; Phillips, Justin; Phillips, Nicole; Pierson, Ronald; Piovezan, Mauro; Podhorski, Adam; Pollari, Mika; Pontecorvo, Michael; Poppenk, Jordan; Posner, Holly; Potkin, Steven; Potter, Guy; Potter, Elizabeth; Poulin, Stephane; Prasad, Gautam; Prenger, Kurt; Prince, Jerry; Priya, Anandh; Puchakayala, Shashidhar Reddy; Qiu, Ruolun; Qiu, Anqi; Qiu, Wendy; Qualls, Constance Dean; Rabie, Huwaida; Rajeesh, Rajeesh; Rallabandi, V. P. Subramanyam; Ramage, Amy; Randolph, Christopher; Rao, Anil; Rao, Divya; Raubertas, Richard; Ray, Debashis; Razak, Hana; Redolfi, Alberto; Reed, Bruce; Reid, Andrew; Reilhac, Anthonin; Reinsberger, Claus; Restrepo, Lucas; Retico, Alessandra; Richards, John; Riddle, William; Ries, Michele; Rincon, Mariano; Rischall, Matt; Rizk-Jackson, Angela; Robieson, Weining; Rocha-Rego, Vanessa; Rogalski, Emily; Rogers, Elizabeth; Rojas, Ignacio; Rojas Balderrama, Javier; Romero, Klaus; Rorden, Chris; Rosand, Jonathan; Rosen, Allyson; Rosen, Ori; Rosenberg, Paul; Ross, David; Roubini, Eli; Rousseau, François; Rowe, Christopher; Rubin, Daniel; Rubright, Jonathan; Ruiz, Agustin; Rusinek, Henry; Ryan, Laurie; Saad, Ahmed; Sabbagh, Marway; Sabuncu, Mert; Sachs, Michael; Sadeghi, Ali; Said, Yasmine; Saint-Aubert, Laure; Sakata, Muneyuki; Salat, David; Salmon, David; Salter, Hugh; Samwald, Matthias; Sanchez, Luciano; Sanders, Elizabeth; Sanjo, Nobuo; Sarnel, Haldun; Sato, Hajime; Sato, Shinji; Saumier, Daniel; Savio, Alexandre; Sawada, Ikuhisa; Saykin, Andrew; Schaffer, J. David; Scharre, Douglas; Schegerin, Marc; Schlosser, Gretchen; Schmand, Ben; Schmansky, Nick; Schmidt, Mark; Schmidt-Wilcke, Tobias; Schneider, Lon; Schramm, Hauke; Schuerch, Markus; Schwartz, Eben; Schwartz, Craig; Schwarz, Adam; Seethamraju, Ravi; Seixas, Flavio; Selnes, Per; Senjem, Matthew; Senlin, Wang; Seo, Sang Won; Sethuraman, Gopalan; Sevigny, Jeffrey; Sfikas, Giorgos; Sghedoni, Roberto; Shah, Said Khalid; Shahbaba, Babak; Shams, Soheil; Shattuck, David; Shaw, Leslie; Sheela, Jaba; Shen, Weijia; Shen, Qian; Shera, David; Sherman, John; Sherva, Richard; Shi, Feng; Shukla, Vinay; Shuler, Catherine; Shulman, Joshua; Siegel, Rene; Siemers, Eric; Silveira, Margarida; Silver, Michael; Silverman, Daniel; Sim, Ida; Simmons, Andy; Simoes, Rita; Simon, Melvin; Simpson, Ivor; Singh, Simer Preet; Singh, Nikhil; Siuciak, Judy; Sjogren, Niclas; Skinner, Jeannine; Skup, Martha; Small, Gary; Smith, Michael; Smith, Benjamin; Smith, Charles; Smyth, Timothy; Snow, Sarah; Soares, Holly; Soldea, Octavian; Solomon, Paul; Solomon, Alan; Som, Subhojit; Song, Changhong; Song, Mingli; Sosova, Iveta; Soudah, Eduardo; Soydemir, Melih; Spampinato, Maria Vittoria; Spenger, Christian; Sperling, Reisa; Spiegel, Rene; Spies, Lothar; Squarcia, Sandro; Squire, Larry; Staff, Roger; Stern, Yaakov; Straw, Jack; Stricker, Nikki; Strittmatter, Stephen; Stühler, Elisabeth; Styren, Scot; Subramanian, Vijayalakshmi; Sugishita, Morihiro; Sukkar, Rafid; Sun, Jia; Sun, Ying; Sun, Yu; Sundell, Karen; Suri, Muhammad; Suzuki, Akiyuki; Svetnik, Vladimir; Swan, Melanie; Takahasi, Tetsuhiko; Takeuchi, Tomoko; Tanaka, Shoji; Tanchi, Chaturaphat; Tancredi, Daniel; Tao, Wenwen; Tao, Dacheng; Taylor-Reinwald, Lisa; Teng, Edmond; Terlizzi, Rita; Thames, April; Thiele, Frank; Thomas, Benjamin; Thomas, Ronald; Thompson, Paul; Thompson, Wesley; Thornton-Wells, Tricia; Thorvaldsson, Valgeir; Thurfjell, Lennart; Titeux, Laurence; Tokuda, Takahiko; Toledo, Juan B.; Tolli, Tuomas; Toma, Ahmed; Tomita, Naoki; Toro, Roberto; Torrealdea, Patxi; Tousian, Mona; Toussaint, Paule; Toyoshiba, Hiroyoshi; Tractenberg, Rochelle E.; Trittschuh, Emily; Trojanowski, John; Truran, Diana; Tsechpenakis, Gavriil; Tucker-Drob, Elliot; Tufail, Ahsan; Tung, Joyce; Turken, And; Ueda, Yoji; Ullrich, Lauren; Umadevi Venkataraju, Kannan; Umar, Nisser; Uzunbas, Gokhan; van de Nes, Joseph; van der Brug, Marcel; van Horn, John; van Leemput, Koen; van Train, Kenneth; van Zeeland, Ashley; Vasanawala, Minal; Vemuri, Prashanthi; Verwaerde, Philippe; Videbaek, Charlotte; Vidoni, Eric; Villanueva-Meyer, Javier; Visser, Pieter Jelle; Vitolo, Ottavio; Vounou, Maria; Wade, Sara; Walhovd, Kristine B.; Wan, Hong; Wang, Huanli; Wang, Yongmei Michelle; Wang, Yalin; Wang, Angela; Wang, Lei; Wang, Yue; Wang, Xu; Wang, Ze; Wang, Yaping; Wang, Tiger; Wang, Alex; Wang, Huali; Wang, Li-San; Wang, Wei; Wang, Li; Ward, Michael; Warfield, Simon; Waring, Stephen; Watanabe, Toshiyuki; Webb, David; Wei, Lili; Weiner, Michael; Wen, Shu-Hui; Wenjing, Li; Wenzel, Fabian; Westlye, Lars T.; Whitcher, Brandon; Whitlow, Christopher; Whitwell, Jennifer; Wilhelmsen, Kirk; Williams, David; Wilmot, Beth; Wimsatt, Matt; Wingo, Thomas; Wiste, Heather; Wolfson, Tanya; Wolke, Ira; Wolz, Robin; Woo, Jongwook; Woo, Ellen; Woods, Lynn; Worth, Andrew; Worth, Eric; Wouters, Hans; Wu, Teresa; Wu, Yi-Gen; Wu, Liang; Wu, Xiaoling; Wyman, Bradley; Wyss-Coray, Tony; Xiao, Guanghua; Xiao, Liu; Xie, Sharon; Xu, Shunbin; Xu, Ye; Xu, Yi-Zheng; Xu, Guofan; Xu, Jun; Yamane, Tomohiko; Yamashita, Fumio; Yan, Yunyi; Yan, Pingkun; Yang, Eric; Yang, Jinzhong; Yang, Qing X.; Yang, Zijiang; Yang, Guang; Yang, Zhitong; Yang, Wenlu; Ye, Liang; Ye, Byoung Seok; Ye, Jieping; Ye, Jong; Yee, Laura; Yesavage, Jerome; Ying, Song; Yoo, Bongin; Young, Jonathan; Yu, Shiwei; Yu, Dongchuan; Yuan, Guihong; Yuan, Kai; Yushkevich, Paul; Zaborszky, Laszlo; Zagorodnov, Vitali; Zagorski, Michael; Zawadzki, Rezi; Zeitzer, Jamie; Zelinski, Elizabeth; Zhang, Kurt; Zhang, Huixiong; Zhang, Tianhao; Zhang, Xin; Zhang, Ping; Zhang, Bin; Zhang, Jing; Zhang, Linda; Zhang, Lijun; Zhang, Zhiguo; Zhao, Qinying; Zhao, Jim; Zhao, Peng; Zhen, Xiantong; Zheng, Yuanjie; Zhijun, Yao; Zhou, Bin; Zhou, Sheng; Zhu, Wen; Zhu, Hongtu; Zhu, Wanlin; Zilka, Samantha; Zito, Giancarlo; Zou, Heng

    2011-01-01

    Amyloid-β accumulation in the brain is thought to be one of the earliest events in Alzheimer's disease, possibly leading to synaptic dysfunction, neurodegeneration and cognitive/functional decline. The earliest detectable changes seen with neuroimaging appear to be amyloid-β accumulation detected by

  12. The architecture of amyloid-like peptide fibrils revealed by X-ray scattering, diffraction and electron microscopy

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    Langkilde, Annette E., E-mail: annette.langkilde@sund.ku.dk [University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen (Denmark); Morris, Kyle L.; Serpell, Louise C. [University of Sussex, Falmer, Brighton (United Kingdom); Svergun, Dmitri I. [European Molecular Biology Laboratory, Hamburg Outstation, 22607 Hamburg (Germany); Vestergaard, Bente [University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen (Denmark)

    2015-04-01

    The aggregation process and the fibril state of an amyloidogenic peptide suggest monomer addition to be the prevailing mechanism of elongation and a model of the peptide packing in the fibrils has been obtained. Structural analysis of protein fibrillation is inherently challenging. Given the crucial role of fibrils in amyloid diseases, method advancement is urgently needed. A hybrid modelling approach is presented enabling detailed analysis of a highly ordered and hierarchically organized fibril of the GNNQQNY peptide fragment of a yeast prion protein. Data from small-angle X-ray solution scattering, fibre diffraction and electron microscopy are combined with existing high-resolution X-ray crystallographic structures to investigate the fibrillation process and the hierarchical fibril structure of the peptide fragment. The elongation of these fibrils proceeds without the accumulation of any detectable amount of intermediate oligomeric species, as is otherwise reported for, for example, glucagon, insulin and α-synuclein. Ribbons constituted of linearly arranged protofilaments are formed. An additional hierarchical layer is generated via the pairing of ribbons during fibril maturation. Based on the complementary data, a quasi-atomic resolution model of the protofilament peptide arrangement is suggested. The peptide structure appears in a β-sheet arrangement reminiscent of the β-zipper structures evident from high-resolution crystal structures, with specific differences in the relative peptide orientation. The complexity of protein fibrillation and structure emphasizes the need to use multiple complementary methods.

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

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    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.

  14. Intravenous immunglobulin binds beta amyloid and modifies its aggregation, neurotoxicity and microglial phagocytosis in vitro.

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    Susann Cattepoel

    Full Text Available Intravenous Immunoglobulin (IVIG has been proposed as a potential therapeutic for Alzheimer's disease (AD and its efficacy is currently being tested in mild-to-moderate AD. Earlier studies reported the presence of anti-amyloid beta (Aβ antibodies in IVIG. These observations led to clinical studies investigating the potential role of IVIG as a therapeutic agent in AD. Also, IVIG is known to mediate beneficial effects in chronic inflammatory and autoimmune conditions by interfering with various pathological processes. Therefore, we investigated the effects of IVIG and purified polyclonal Aβ-specific antibodies (pAbs-Aβ on aggregation, toxicity and phagocytosis of Aβ in vitro, thus elucidating some of the potential mechanisms of action of IVIG in AD patients. We report that both IVIG and pAbs-Aβ specifically bound to Aβ and inhibited its aggregation in a dose-dependent manner as measured by Thioflavin T assay. Additionally, IVIG and the purified pAbs-Aβ inhibited Aβ-induced neurotoxicity in the SH-SY5Y human neuroblastoma cell line and prevented Aβ binding to rat primary cortical neurons. Interestingly, IVIG and pAbs-Aβ also increased the number of phagocytosing cells as well as the amount of phagocytosed fibrillar Aβ by BV-2 microglia. Phagocytosis of Aβ depended on receptor-mediated endocytosis and was accompanied by upregulation of CD11b expression. Importantly, we could also show that Privigen dose-dependently reversed Aβ-mediated LTP inhibition in mouse hippocampal slices. Therefore, our in vitro results suggest that IVIG may have an impact on different processes involved in AD pathogenesis, thereby promoting further understanding of the effects of IVIG observed in clinical studies.

  15. High molecular weight of polysaccharides from Hericium erinaceus against amyloid beta-induced neurotoxicity.

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    Cheng, Jai-Hong; Tsai, Chia-Ling; Lien, Yi-Yang; Lee, Meng-Shiou; Sheu, Shyang-Chwen

    2016-06-07

    Hericium erinaceus (HE) is a well-known mushroom in traditional Chinese food and medicine. HE extracts from the fruiting body and mycelia not only exhibit immunomodulatory, antimutagenic and antitumor activity but also have neuroprotective properties. Here, we purified HE polysaccharides (HEPS), composed of two high molecular weight polysaccharides (1.7 × 10(5) Da and 1.1 × 10(5) Da), and evaluated their protective effects on amyloid beta (Aβ)-induced neurotoxicity in rat pheochromocytoma PC12 cells. HEPS were prepared and purified using a 95 % ethanol extraction method. The components of HEPS were analyzed and the molecular weights of the polysaccharides were determined using high-pressure liquid chromatography (HPLC). The neuroprotective effects of the polysaccharides were evaluated through a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and an MTT assay and by quantifying reactive oxygen species (ROS) and mitochondrial membrane potentials (MMP) of Aβ-induced neurotoxicity in cells. Our results showed that 250 μg/ml HEPS was harmless and promoted cell viability with 1.2 μM Aβ treatment. We observed that the free radical scavenging rate exceeded 90 % when the concentration of HEPS was higher than 1 mg/mL in cells. The HEPS decreased the production of ROS from 80 to 58 % in a dose-dependent manner. Cell pretreatment with 250 μg/mL HEPS significantly reduced Aβ-induced high MMPs from 74 to 51 % and 94 to 62 % at 24 and 48 h, respectively. Finally, 250 μg/mL of HEPS prevented Aβ-induced cell shrinkage and nuclear degradation of PC12 cells. Our results demonstrate that HEPS exhibit antioxidant and neuroprotective effects on Aβ-induced neurotoxicity in neurons.

  16. Amyloid beta inhibits olfactory bulb activity and the ability to smell.

    Directory of Open Access Journals (Sweden)

    Reynaldo Alvarado-Martínez

    Full Text Available Early olfactory dysfunction has been consistently reported in both Alzheimer's disease (AD and in transgenic mice that reproduce some features of this disease. In AD transgenic mice, alteration in olfaction has been associated with increased levels of soluble amyloid beta protein (Aβ as well as with alterations in the oscillatory network activity recorded in the olfactory bulb (OB and in the piriform cortex. However, since AD is a multifactorial disease and transgenic mice suffer a variety of adaptive changes, it is still unknown if soluble Aβ, by itself, is responsible for OB dysfunction both at electrophysiological and behavioral levels. Thus, here we tested whether or not Aβ directly affects OB network activity in vitro in slices obtained from mice and rats and if it affects olfactory ability in these rodents. Our results show that Aβ decreases, in a concentration- and time-dependent manner, the network activity of OB slices at clinically relevant concentrations (low nM and in a reversible manner. Moreover, we found that intrabulbar injection of Aβ decreases the olfactory ability of rodents two weeks after application, an effect that is not related to alterations in motor performance or motivation to seek food and that correlates with the presence of Aβ deposits. Our results indicate that Aβ disrupts, at clinically relevant concentrations, the network activity of the OB in vitro and can trigger a disruption in olfaction. These findings open the possibility of exploring the cellular mechanisms involved in early pathological AD as an approach to reduce or halt its progress.

  17. A carboxylated Zn-phthalocyanine inhibits fibril formation of Alzheimer's amyloid β peptide.

    Science.gov (United States)

    Tabassum, Shatera; Sheikh, Abdullah M; Yano, Shozo; Ikeue, Takafumi; Handa, Makoto; Nagai, Atsushi

    2015-02-01

    Amyloid β (Aβ), a 39-42 amino acid peptide derived from amyloid precursor protein, is deposited as fibrils in Alzheimer's disease brains, and is considered to play a major role in the pathogenesis of the disease. We have investigated the effects of a water-soluble Zn-phthalocyanine, ZnPc(COONa)₈, a macrocyclic compound with near-infrared optical properties, on Aβ fibril formation in vitro. A thioflavin T fluorescence assay showed that ZnPc(COONa)₈ significantly inhibited Aβ fibril formation, increasing the lag time and dose-dependently decreasing the plateau level of fibril formation. Moreover, it destabilized pre-formed Aβ fibrils, resulting in an increase in low-molecular-weight species. After fibril formation in the presence of ZnPc(COONa)₈, immunoprecipitation of Aβ₁₋₄₂ using Aβ-specific antibody followed by near-infrared scanning demonstrated binding of ZnPc(COONa)₈ to Aβ₁₋₄₂. A study using the hydrophobic fluorescent probe 8-anilino-1-naphthalenesulfonic acid showed that ZnPc(COONa)8 decreased the hydrophobicity during Aβ₁₋₄₂ fibril formation. CD spectroscopy showed an increase in the α helix structure and a decrease in the β sheet structure of Aβ₁₋₄₀ in fibril-forming buffer containing ZnPc(COONa)₈. SDS/PAGE and a dot-blot immunoassay showed that ZnPc(COONa)₈ delayed the disappearance of low-molecular-weight species and the appearance of higher-molecular-weight oligomeric species of Aβ₁₋₄₂. A cell viability assay showed that ZnPc(COONa)₈ was not toxic to a neuronal cell line (A1), but instead protected A1 cells against Aβ₁₋₄₂-induced toxicity. Overall, our results indicate that ZnPc(COONa)₈ binds to Aβ and decreases the hydrophobicity, and this change is unfavorable for Aβ oligomerization and fibril formation. © 2014 FEBS.

  18. The effect of a beta-lactamase inhibitor peptide on bacterial membrane structure and integrity: a comparative study.

    Science.gov (United States)

    Alaybeyoglu, Begum; Uluocak, Bilge Gedik; Akbulut, Berna Sariyar; Ozkirimli, Elif

    2017-05-01

    Co-administration of beta-lactam antibiotics and beta-lactamase inhibitors has been a favored treatment strategy against beta-lactamase-mediated bacterial antibiotic resistance, but the emergence of beta-lactamases resistant to current inhibitors necessitates the discovery of novel non-beta-lactam inhibitors. Peptides derived from the Ala46-Tyr51 region of the beta-lactamase inhibitor protein are considered as potent inhibitors of beta-lactamase; unfortunately, peptide delivery into the cell limits their potential. The properties of cell-penetrating peptides could guide the design of beta-lactamase inhibitory peptides. Here, our goal is to modify the peptide with the sequence RRGHYY that possesses beta-lactamase inhibitory activity under in vitro conditions. Inspired by the work on the cell-penetrating peptide pVEC, our approach involved the addition of the N-terminal hydrophobic residues, LLIIL, from pVEC to the inhibitor peptide to build a chimera. These residues have been reported to be critical in the uptake of pVEC. We tested the potential of RRGHYY and its chimeric derivative as a beta-lactamase inhibitory peptide on Escherichia coli cells and compared the results with the action of the antimicrobial peptide melittin, the beta-lactam antibiotic ampicillin, and the beta-lactamase inhibitor potassium clavulanate to get mechanistic details on their action. Our results show that the addition of LLIIL to the N-terminus of the beta-lactamase inhibitory peptide RRGHYY increases its membrane permeabilizing potential. Interestingly, the addition of this short stretch of hydrophobic residues also modified the inhibitory peptide such that it acquired antimicrobial property. We propose that addition of the hydrophobic LLIIL residues to the peptide N-terminus offers a promising strategy to design novel antimicrobial peptides in the battle against antibiotic resistance. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd. Copyright © 2017 European

  19. COPS5 (Jab1) protein increases β site processing of amyloid precursor protein and amyloid β peptide generation by stabilizing RanBP9 protein levels.

    Science.gov (United States)

    Wang, Hongjie; Dey, Debleena; Carrera, Ivan; Minond, Dmitriy; Bianchi, Elisabetta; Xu, Shaohua; Lakshmana, Madepalli K

    2013-09-13

    Increased processing of amyloid precursor protein (APP) and accumulation of neurotoxic amyloid β peptide (Aβ) in the brain is central to the pathogenesis of Alzheimer's disease (AD). Therefore, the identification of molecules that regulate Aβ generation is crucial for future therapeutic approaches for AD. We demonstrated previously that RanBP9 regulates Aβ generation in a number of cell lines and primary neuronal cultures by forming tripartite protein complexes with APP, low-density lipoprotein-related protein, and BACE1, consequently leading to increased amyloid plaque burden in the brain. RanBP9 is a scaffold protein that exists and functions in multiprotein complexes. To identify other proteins that may bind RanBP9 and regulate Aβ levels, we used a two-hybrid analysis against a human brain cDNA library and identified COPS5 as a novel RanBP9-interacting protein. This interaction was confirmed by coimmunoprecipitation experiments in both neuronal and non-neuronal cells and mouse brain. Colocalization of COPS5 and RanBP9 in the same subcellular compartments further supported the interaction of both proteins. Furthermore, like RanBP9, COPS5 robustly increased Aβ generation, followed by increased soluble APP-β (sAPP-β) and decreased soluble-APP-α (sAPP-α) levels. Most importantly, down-regulation of COPS5 by siRNAs reduced Aβ generation, implying that endogenous COPS5 regulates Aβ generation. Finally, COPS5 levels were increased significantly in AD brains and APΔE9 transgenic mice, and overexpression of COPS5 strongly increased RanBP9 protein levels by increasing its half-life. Taken together, these results suggest that COPS5 increases Aβ generation by increasing RanBP9 levels. Thus, COPS5 is a novel RanBP9-binding protein that increases APP processing and Aβ generation by stabilizing RanBP9 protein levels.

  20. Organotypic vibrosections from whole brain adult Alzheimer mice (overexpressing amyloid-precursor-protein with the Swedish-Dutch-Iowa mutations as a model to study clearance of beta-amyloid plaques

    Directory of Open Access Journals (Sweden)

    Christian eHumpel

    2015-04-01

    Full Text Available Alzheimer´s disease is a severe neurodegenerative disorder of the brain, pathologically characterized by extracellular beta-amyloid plaques, intraneuronal Tau inclusions, inflammation, reactive glial cells, vascular pathology and neuronal cell death. The degradation and clearance of beta-amyloid plaques is an interesting therapeutic approach, and the proteases neprilysin (NEP, insulysin and matrix metalloproteinases (MMP are of particular interest. The aim of this project was to establish and characterize a simple in vitro model to study the degrading effects of these proteases. Organoytpic brain vibrosections (120 µm thick were sectioned from adult (9 month old wildtype and transgenic mice (expressing amyloid precursor protein (APP harboring the Swedish K670N/M671L, Dutch E693Q, and Iowa D694N mutations; APP_SDI and cultured for 2 weeks. Plaques were stained by immunohistochemistry for beta-amyloid and Thioflavin S. Our data show that plaques were evident in 2 week old cultures from 9 month old transgenic mice. These plaques were surrounded by reactive GFAP+ astroglia and Iba1+ microglia. Incubation of fresh slices for 2 weeks with 1-0.1-0.01 µg/ml of NEP, insulysin, MMP-2 or MMP-9 showed that NEP, insulysin and MMP-9 markedly degradeded beta-amyloid plaques but only at the highest concentration. Our data provide for the first time a potent and powerful living brain vibrosection model containing a high number of plaques, which allows to rapidly and simply study the degradation and clearance of beta-amyloid plaques in vitro.

  1. Cholesterol enhances amyloid {beta} deposition in mouse retina by modulating the activities of A{beta}-regulating enzymes in retinal pigment epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiying [Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519 (Japan); Ohno-Matsui, Kyoko, E-mail: k.ohno.oph@tmd.ac.jp [Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519 (Japan); Morita, Ikuo [Section of Cellular Physiological Chemistry, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519 (Japan)

    2012-08-10

    Highlights: Black-Right-Pointing-Pointer Cholesterol-treated RPE produces more A{beta} than non-treated RPE. Black-Right-Pointing-Pointer Neprilysin expression and activity decreased in cholesterol-treated RPE. Black-Right-Pointing-Pointer {alpha}-Secretase expression and activity decreased in cholesterol-treated RPE. Black-Right-Pointing-Pointer Cholesterol-enriched diet induced subRPE deposits in aged mice. Black-Right-Pointing-Pointer A{beta} were present in cholesterol-enriched-diet-induced subRPE deposits in aged mice. -- Abstract: Subretinally-deposited amyloid {beta} (A{beta}) is a main contributor of developing age-related macular degeneration (AMD). However, the mechanism causing A{beta} deposition in AMD eyes is unknown. Hypercholesterolemia is a significant risk for developing AMD. Thus, we investigated the effects of cholesterol on A{beta} production in retinal pigment epithelial (RPE) cells in vitro and in the mouse retina in vivo. RPE cells isolated from senescent (12-month-old) C57BL/6 mice were treated with 10 {mu}g/ml cholesterol for 48 h. A{beta} amounts in culture supernatants were measured by ELISA. Activity and expression of enzymes and proteins that regulate A{beta} production were examined by activity assay and real time PCR. The retina of mice fed cholesterol-enriched diet was examined by transmission electron microscopy. Cholesterol significantly increased A{beta} production in cultured RPE cells. Activities of A{beta} degradation enzyme; neprilysin (NEP) and anti-amyloidogenic secretase; {alpha}-secretase were significantly decreased in cell lysates of cholesterol-treated RPE cells compared to non-treated cells, but there was no change in the activities of {beta}- or {gamma}-secretase. mRNA levels of NEP and {alpha}-secretase (ADAM10 and ADAM17) were significantly lower in cholesterol-treated RPE cells than non-treated cells. Senescent (12-month-old) mice fed cholesterol-enriched chow developed subRPE deposits containing A{beta}, whereas

  2. Evaluation of beta-cell secretory capacity using glucagon-like peptide 1

    DEFF Research Database (Denmark)

    Vilsbøll, Tina; Nielsen, Mette Toft; Krarup, T

    2000-01-01

    Beta-cell secretory capacity is often evaluated with a glucagon test or a meal test. However, glucagon-like peptide 1 (GLP-1) is the most insulinotropic hormone known, and the effect is preserved in type 2 diabetic patients.......Beta-cell secretory capacity is often evaluated with a glucagon test or a meal test. However, glucagon-like peptide 1 (GLP-1) is the most insulinotropic hormone known, and the effect is preserved in type 2 diabetic patients....

  3. Evidence that a synthetic amyloid-ß oligomer-binding peptide (ABP) targets amyloid-ß deposits in transgenic mouse brain and human Alzheimer's disease brain.

    Science.gov (United States)

    Chakravarthy, Balu; Ito, Shingo; Atkinson, Trevor; Gaudet, Chantal; Ménard, Michel; Brown, Leslie; Whitfield, James

    2014-03-14

    The synthetic ~5 kDa ABP (amyloid-ß binding peptide) consists of a region of the 228 kDa human pericentrioloar material-1 (PCM-1) protein that selectively and avidly binds in vitro Aβ1-42 oligomers, believed to be key co-drivers of Alzheimer's disease (AD), but not monomers (Chakravarthy et al., (2013) [3]). ABP also prevents Aß1-42 from triggering the apoptotic death of cultured human SHSY5Y neuroblasts, likely by sequestering Aß oligomers, suggesting that it might be a potential AD therapeutic. Here we support this possibility by showing that ABP also recognizes and binds Aβ1-42 aggregates in sections of cortices and hippocampi from brains of AD transgenic mice and human AD patients. More importantly, ABP targets Aβ1-42 aggregates when microinjected into the hippocampi of the brains of live AD transgenic mice. Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.

  4. Levels of amyloid-beta-42 and CSF pressure are directly related in patients with Alzheimer's disease.

    Science.gov (United States)

    Schirinzi, Tommaso; Di Lazzaro, Giulia; Sancesario, Giulia Maria; Colona, Vito Luigi; Scaricamazza, Eugenia; Mercuri, Nicola Biagio; Martorana, Alessandro; Sancesario, Giuseppe

    2017-12-01

    Experimental data suggest that the cerebrospinal fluid (CSF) dynamic is involved in the clearance of beta-amyloid, a key event in the pathogenesis of Alzheimer's disease (AD). At this regard no evidence still exists in vivo. In this study we explored the relationships between CSF pressure and AD pathology, as measured with CSF core biomarkers. We enrolled 16 patients with probable AD and 21 controls, collecting demographics, clinical data, CSF opening pressure and CSF levels of beta-amyloid-42 fragment (Aβ42), total-tau (t-tau), phosphorylated-tau-181 (p-tau), albumin and albumin ratio. Differences between the groups were calculated with non-parametric tests, while correlations among all parameters were separately calculated with Spearman's test in each group. The groups significantly differed in biomarkers' concentration with lower Aβ42, and higher t-tau and p-tau in AD patients. Moreover, CSF pressure was significantly lower in AD group (11.0 ± 2.8 vs. 13.3 ± 3.0 mmHg, p < 0.05) and directly correlated with Aβ42 levels (R = 0.512; p < 0.05), but not with other biomarkers or parameters. No significant correlations emerged for biomarkers in control group. AD patients exhibit low CSF pressure whose values are directly and selectively related to CSF Aβ42 levels. This interesting correlation may confirm in vivo the association between CSF dynamic and beta-amyloid metabolism occurring in AD.

  5. pH-dependent kinetics of copper ions binding to amyloidpeptide.

    Science.gov (United States)

    Bin, Yannan; Chen, Shu; Xiang, Juan

    2013-02-01

    Interactions of amyloidpeptide (Aβ) with Cu(2+) are known to be pH-dependent and believed to play a crucial role in the neurotoxicity of Alzheimer's disease (AD). Some research has revealed that injured brains with lowered pH have higher risks of developing AD. However, reported experiments were performed under neutral or mildly acidic conditions, and no reports about the affinity of Aβ-Cu(2+) below pH6.0. In this study, surface plasmon resonance (SPR) sensor with immobilized Aβ was used to investigate the formation of Aβ-Cu(2+) complexes under acidic pH conditions. Dissociation constants were calculated and shown to be pH-dependent, ranging from 3.5×10(-8)M to 8.7×10(-3)M in the pH range from 7.0 to 4.0. The physiological significance of K(d) was preliminarily investigated by monitoring the generation of OH() in aerobic solutions containing Aβ-Cu(2+) and Cu(2+). The results imply that acidic conditions could aggravate the oxidative stress in the presence of Cu(2+), and the weak affinities of Aβ-Cu(2+) under mildly acidic pH of 5.0-6.0 could further enhance the oxidative damage. However, the oxidative stress effect of Aβ is negligible due to the suppressed formation of Aβ-Cu(2+) below pH5.0. This work is useful for the in-depth understanding of the role of Aβ-Cu(2+) in AD neuropathology. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

  6. 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.

  7. 9,10-Anthraquinone hinders β-aggregation: How does a small molecule interfere with Aβ-peptide amyloid fibrillation?

    Science.gov (United States)

    Convertino, Marino; Pellarin, Riccardo; Catto, Marco; Carotti, Angelo; Caflisch, Amedeo

    2009-01-01

    Amyloid aggregation is linked to a number of neurodegenerative syndromes, the most prevalent one being Alzheimer's disease. In this pathology, the β-amyloid peptides (Aβ) aggregate into oligomers, protofibrils, and fibrils and eventually into plaques, which constitute the characteristic hallmark of Alzheimer's disease. Several low-molecular-weight compounds able to impair the Aβ aggregation process have been recently discovered; yet, a detailed description of their interactions with oligomers and fibrils is hitherto missing. Here, molecular dynamics simulations are used to investigate the influence of two relatively similar tricyclic, planar compounds, that is, 9, 10-anthraquinone (AQ) and anthracene (AC), on the early phase of the aggregation of the Aβ heptapeptide segment H14QKLVFF20, the hydrophobic stretch that promotes the Aβ self-assembly. The simulations show that AQ interferes with β-sheet formation more than AC. In particular, AQ intercalates into the β-sheet because polar interactions between the compound and the peptide backbone destabilize the interstrand hydrogen bonds, thereby favoring disorder. The thioflavin T-binding assay indicates that AQ, but not AC, sensibly reduces the amount of aggregated Aβ1–40 peptide. Taken together, the in silico and in vitro results provide evidence that structural perturbations by AQ can remarkably affect ordered oligomerization. Moreover, the simulations shed light at the atomic level on the interactions between AQ and Aβ oligomers, providing useful insights for the design of small-molecule inhibitors of aggregation with therapeutic potential in Alzheimer's disease. PMID:19309732

  8. Methyl Salicylate Lactoside Protects Neurons Ameliorating Cognitive Disorder Through Inhibiting Amyloid Beta-Induced Neuroinflammatory Response in Alzheimer’s Disease

    Science.gov (United States)

    Li, Jinze; Ma, Xiaowei; Wang, Yu; Chen, Chengjuan; Hu, Min; Wang, Linlin; Fu, Junmin; Shi, Gaona; Zhang, Dongming; Zhang, Tiantai

    2018-01-01

    Neuroinflammatory reactions mediated by microglia and astrocytes have been shown to play a key role in early progression of Alzheimer’s disease (AD). Increased evidences have demonstrated that neurons exacerbate local inflammatory reactions by producing inflammatory mediators and act as an important participant in the pathogenesis of AD. Methyl salicylate lactoside (MSL) is an isolated natural product that is part of a class of novel non-steroidal anti-inflammatory drugs (NSAID). In our previous studies, we demonstrated that MSL exhibited therapeutic effects on arthritis-induced mice and suppressed the activation of glial cells. In the current study, we investigated the effects of MSL on cognitive function and neuronal protection induced by amyloid-beta peptides (Aβ) and explored potential underlying mechanisms involved. Amyloid precursor protein (APP) and presenilin 1 (PS1) double transgenic mice were used to evaluate the effects of MSL through behavioral testing and neuronal degenerative changes. In addition, copper-injured APP Swedish mutation overexpressing SH-SY5Y cells were used to determine the transduction of cyclooxygenase (COX) and mitogen-activated protein kinase (MAPK) pathways. Our results indicated that at an early stage, MSL treatment ameliorated cognitive impairment and neurodegeneration in APP/PS1 mice. Moreover, in an in vitro AD model, MSL treatment protected injured cells by increasing cell viability, improving mitochondrial dysfunction, and decreasing oxidative damage. In addition, MSL inhibited the phosphorylated level of c-Jun N-terminal kinase (JNK) and p38 MAPK, and suppressed the expression of COX-1/2. As a novel NSAIDs and used for the treatment in early stage of AD, MSL clearly demonstrated cognitive preservation by protecting neurons via a pleiotropic anti-inflammatory effect in the context of AD-associated deficits. Therefore, early treatment of anti-inflammatory therapy may be an effective strategy for treating AD. PMID:29636677

  9. A Peptide Derived from the HIV-1 gp120 Coreceptor-Binding Region Promotes Formation of PAP248-286 Amyloid Fibrils to Enhance HIV-1 Infection.

    Directory of Open Access Journals (Sweden)

    Jinquan Chen

    Full Text Available Semen is a major vehicle for HIV transmission. Prostatic acid phosphatase (PAP fragments, such as PAP248-286, in human semen can form amyloid fibrils to enhance HIV infection. Other endogenous or exogenous factors present during sexual intercourse have also been reported to promote the formation of seminal amyloid fibrils.Here, we demonstrated that a synthetic 15-residue peptide derived from the HIV-1 gp120 coreceptor-binding region, designated enhancing peptide 2 (EP2, can rapidly self-assemble into nanofibers. These EP2-derivated nanofibers promptly accelerated the formation of semen amyloid fibrils by PAP248-286, as shown by Thioflavin T (ThT and Congo red assays. The amyloid fibrils presented similar morphology, assessed via transmission electron microscopy (TEM, in the presence or absence of EP2. Circular dichroism (CD spectroscopy revealed that EP2 accelerates PAP248-286 amyloid fibril formation by promoting the structural transition of PAP248-286 from a random coil into a cross-β-sheet. Newly formed semen amyloid fibrils effectively enhanced HIV-1 infection in TZM-bl cells and U87 cells by promoting the binding of HIV-1 virions to target cells.Nanofibers composed of EP2 promote the formation of PAP248-286 amyloid fibrils and enhance HIV-1 infection.

  10. Novel Detox Gel Depot sequesters β-Amyloid Peptides in a mouse model of Alzheimer’s Disease

    Science.gov (United States)

    Sundaram, Ranjini K.; Kasinathan, Chinnaswamy; Stein, Stanley; Sundaram, Pazhani

    2012-01-01

    Alzheimer’s Disease (AD), a debilitating neurodegenerative disease is caused by aggregation and accumulation of a 39–43 amino acid peptide (amyloid β or Aβ) in brain parenchyma and cerebrovasculature. The rational approach would be to use drugs that interfere with Aβ-Aβ interaction and disrupt polymerization. Peptide ligands capable of binding to the KLVFF (amino acids 16–20) region in the Aβ molecule have been investigated as possible drug candidates. Retro-inverso (RI) peptide of this pentapeptide, ffvlk, has been shown to bind artificial fibrils made from Aβ with moderate affinity. We hypothesized that a ‘detox gel’, which is synthesized by covalently linking a tetrameric version of RI peptide ffvlk to poly (ethylene glycol) polymer chains will act like a ‘sink’ to capture Aβ peptides from the surrounding environment. We previously demonstrated that this hypothesis works in an in vitro system. The present study extended this hypothesis to an in vivo mouse model of Alzheimer’s Disease and determined the therapeutic effect of our detox gel. We injected detox gel subcutaneously to AD model mice and analyzed brain levels of Aβ-42 and improvement in memory parameters. The results showed a reduction of brain amyloid burden in detox gel treated mice. Memory parameters in the treated mice improved. No undesirable immune response was observed. The data strongly suggest that our detox gel can be used as an effective therapy to deplete brain Aβ levels. Considering recent abandonment of failed antibody based therapies, our detox gel appears to have the advantage of being a non-immune based therapy. PMID:22712003

  11. Key Aging-Associated Alterations in Primary Microglia Response to Beta-Amyloid Stimulation

    Directory of Open Access Journals (Sweden)

    Cláudia Caldeira

    2017-08-01

    Full Text Available Alzheimer’s disease (AD is characterized by a progressive cognitive decline and believed to be driven by the self-aggregation of amyloid-β (Aβ peptide into oligomers and fibrils that accumulate as senile plaques. It is widely accepted that microglia-mediated inflammation is a significant contributor to disease pathogenesis; however, different microglia phenotypes were identified along AD progression and excessive Aβ production was shown to dysregulate cell function. As so, the contribution of microglia to AD pathogenesis remains to be elucidated. In this study, we wondered if isolated microglia cultured for 16 days in vitro (DIV would react differentially from the 2 DIV cells upon treatment with 1000 nM Aβ1–42 for 24 h. No changes in cell viability were observed and morphometric alterations associated to microglia activation, such as volume increase and process shortening, were obvious in 2 DIV microglia, but less evident in 16 DIV cells. These cells showed lower phagocytic, migration and autophagic properties after Aβ treatment than the 2 DIV cultured microglia. Reduced phagocytosis may derive from increased CD33 expression, reduced triggering receptor expressed on myeloid cells 2 (TREM2 and milk fat globule-EGF factor 8 protein (MFG-E8 levels, which were mainly observed in 16 DIV cells. Activation of inflammatory mediators, such as high mobility group box 1 (HMGB1 and pro-inflammatory cytokines, as well as increased expression of Toll-like receptor 2 (TLR2, TLR4 and fractalkine/CX3C chemokine receptor 1 (CX3CR1 cell surface receptors were prominent in 2 DIV microglia, while elevation of matrix metalloproteinase 9 (MMP9 was marked in 16 DIV cells. Increased senescence-associated β-galactosidase (SA-β-gal and upregulated miR-146a expression that were observed in 16 DIV cells showed to increase by Aβ in 2 DIV microglia. Additionally, Aβ downregulated miR-155 and miR-124, and reduced the CD11b+ subpopulation in 2 DIV microglia, while

  12. Amyloid-beta 40 as a biomarker of cognitive impairment in acute ischemic stroke

    Directory of Open Access Journals (Sweden)

    Aleksey A. Kulesh

    2017-01-01

    Full Text Available Aim: to study the role of amyloid-beta 40 (Aβ 40 in the development of cognitive impairment in acute ischemic stroke.Materials and methods. The study included 70 patients aged 33–86 years, 46 men and 24 women. In patients with acute ischemic stroke cognitive status was assessed with Mini-Mental State Examination (MMSE, Montreal Cognitive Assessment Test (MoCA, Frontal Assessment Battery (FAB, Schulte tables, Clock Drawing Test, Test for Semantic Verbal Fluency and Five Words Test. The concentration of Aβ 40 in the cerebrospinal fluid was determined. Morphometric (size of the infarct and leukoaraiosis area, volume of the brain ventricles and hippocampus and diffusion-tensor parameters of MRI (fractional anisotropy of putamen, thalamus, hippocampus, corpus callosum, limbs of the internal capsule, the cingulate, the superior longitudinal and inferior fronto-occipital tracts were studied.Results. The concentration of Aβ 40 in the cerebrospinal fluid was 436,4 (226,0–514,0 pg/ml. The protein level was associated with the result of subtests «Orientation» (MMSE and «Attention» (MoCA, as well as indirect recall with cues in MoCA. Patients with MMSE score of 24–27 points were characterized by a lower concentration of Aβ 40 as compared to patients with a score less than 24 points. Aβ 40 concentration more than 436,4 pg/mL was associated with a more severe somatic co-morbidity of stroke (hypertension, lower hemoglobin and albumin level, higher erythrocyte sedimentation rate, a smaller volume of the brain ventricles, lower fractional anisotropy of the thalamus, cingulate tracts and contralateral hippocampus. Aβ 40 concentration more than 436,4 pg/mL was also associated with a lower global cognitive status (according to the MMSE and MoCA, as well as the reduction in certain cognitive functions, namely, attention, visual-spatial functions and memory.Conclusions. The concentration of Aβ 40 in the cerebrospinal fluid is a biological marker of

  13. Correlations between serum levels of beta amyloid, cerebrospinal levels of tau and phospho tau, and delayed response tasks in young and aged cynomolgus monkeys (Macaca fascicularis)

    DEFF Research Database (Denmark)

    Darusman, Huda Shalahudin; Sajuthi, D; Kalliokoski, O

    2013-01-01

    In an attempt to explore cynomolgus monkeys as an animal model for Alzheimer's disease, the present study focused on the Alzheimer's biomarkers beta amyloid 1-42 (Aβ42 ) in serum, and total tau (t-tau) and phosphorylated tau (p-tau) levels in cerebrospinal fluid.......In an attempt to explore cynomolgus monkeys as an animal model for Alzheimer's disease, the present study focused on the Alzheimer's biomarkers beta amyloid 1-42 (Aβ42 ) in serum, and total tau (t-tau) and phosphorylated tau (p-tau) levels in cerebrospinal fluid....

  14. Characterization of the fine specificity of peptide antibodies to HLA-DQ beta-chain molecules

    DEFF Research Database (Denmark)

    Petersen, J S; Atar, D; Karlsen, Alan E

    1990-01-01

    In an attempt to produce epitope specific antisera which could distinguish two closely associated HLA-DQ beta-chain alleles, we immunized 20 rabbits with synthetic peptides representing sequences from the first domain of the HLA-DQw8 and -DQw7 beta-chain molecules, differing only by one amino acid...... in position 57. Several of the antisera in immunoblotting specifically recognized either the HLA-DQw7 or the HLA-DQw8 beta-chain allele as previously reported. The fine specificity of the antisera was tested in ELISA using synthetic peptides of varying length as solid phase antigen. Two out of the 20 antisera...

  15. Beta-Amyloid Downregulates MDR1-P-Glycoprotein (Abcb1 Expression at the Blood-Brain Barrier in Mice

    Directory of Open Access Journals (Sweden)

    Anja Brenn

    2011-01-01

    Full Text Available Neurovascular dysfunction is an important component of Alzheimer's disease, leading to reduced clearance across the blood-brain barrier and accumulation of neurotoxic β-amyloid (Aβ peptides in the brain. It has been shown that the ABC transport protein P-glycoprotein (P-gp, ABCB1 is involved in the export of Aβ from the brain into the blood. To determine whether Aβ influences the expression of key Aβ transporters, we studied the effects of 1-day subcutaneous Aβ1-40 and Aβ1-42 administration via Alzet mini-osmotic pumps on P-gp, BCRP, LRP1, and RAGE expression in the brain of 90-day-old male FVB mice. Our results demonstrate significantly reduced P-gp, LRP1, and RAGE mRNA expression in mice treated with Aβ1-42 compared to controls, while BCRP expression was not affected. The expression of the four proteins was unchanged in mice treated with Aβ1-40 or reverse-sequence peptides. These findings indicate that, in addition to the age-related decrease of P-gp expression, Aβ1-42 itself downregulates the expression of P-gp and other Aβ-transporters, which could exacerbate the intracerebral accumulation of Aβ and thereby accelerate neurodegeneration in Alzheimer's disease and cerebral β-amyloid angiopathy.

  16. Interhemispheric EEG differences in olfactory bulbectomized rats with different cognitive abilities and brain beta-amyloid levels.

    Science.gov (United States)

    Bobkova, Natalia; Vorobyov, Vasily; Medvinskaya, Natalia; Aleksandrova, Irina; Nesterova, Inna

    2008-09-26

    Alterations in electroencephalogram (EEG) asymmetry and deficits in interhemispheric integration of information have been shown in patients with Alzheimer's disease (AD). However, no direct evidence of an association between EEG asymmetry, morphological markers in the brain, and cognition was found either in AD patients or in AD models. In this study we used rats with bilateral olfactory bulbectomy (OBX) as one of the AD models and measured their learning/memory abilities, brain beta-amyloid levels and EEG spectra in symmetrical frontal and occipital cortices. One year after OBX or sham-surgery, the rats were tested with the Morris water paradigm and assigned to three groups: sham-operated rats, SO, and OBX rats with virtually normal, OBX(+), or abnormal, OBX(-), learning (memory) abilities. In OBX vs. SO, the theta EEG activity was enhanced to a higher extent in the right frontal cortex and in the left occipital cortex. This produced significant interhemispheric differences in the frontal cortex of the OBX(-) rats and in the occipital cortex of both OBX groups. The beta1 EEG asymmetry in SO was attenuated in OBX(+) and completely eliminated in OBX(-). OBX produced highly significant beta2 EEG decline in the right frontal cortex, with OBX(-)>OBX(+) rank order of strength. The beta-amyloid level, examined by post-mortem immunological DOT-analysis in the cortex-hippocampus samples, was about six-fold higher in OBX(-) than in SO, but significantly less (enhanced by 82% vs. SO) in OBX(+) than in OBX(-). The involvement of the brain mediatory systems in the observed EEG asymmetry differences is discussed.

  17. α-Iso-cubebene exerts neuroprotective effects in amyloid beta stimulated microglia activation.

    Science.gov (United States)

    Park, Sun Young; Park, Se Jin; Park, Nan Jeong; Joo, Woo Hong; Lee, Sang-Joon; Choi, Young-Whan

    2013-10-25

    Schisandra chinensis is commonly used for food and as a traditional remedy for the treatment of neuronal disorders. However, it is unclear which component of S. chinensis is responsible for its neuropharmacological effects. To answer this question, we isolated α-iso-cubebene, a dibenzocyclooctadiene lignin, from S. chinensis and determined if it has any anti-neuroinflammatory and neuroprotective properties against amyloid β-induced neuroinflammation in microglia. Microglia that are stimulated by amyloid β increased their production of pro-inflammatory cytokines and chemokines, prostaglandin E2 (PGE2), nitric oxide (NO) and reactive oxygen species (ROS) and the enzymatic activity of matrix metalloproteinase 9 (MMP-9). We found this was all inhibited by α-iso-cubebene. Consistent with these results, α-iso-cubebene inhibited the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2) and MMP-9 in amyloid β-stimulated microglia. Subsequent mechanistic studies revealed that α-iso-cubebene inhibited the phosphorylation and degradation of IκB-α, the phosphorylation and transactivity of NF-κB, and the phosphorylation of MAPK in amyloid β-stimulated microglia. These results suggest that α-iso-cubebene impairs the amyloid β-induced neuroinflammatory response of microglia by inhibiting the NF-κB and MAPK signaling pathways. Importantly, α-iso-cubebene can provide critical neuroprotection for primary cortical neurons against amyloid β-stimulated microglia-mediated neurotoxicity. To the best of our knowledge, this is the first report showing that α-iso-cubebene can provide neuroprotection against, and influence neuroinflammation triggered by, amyloid β activation of microglia. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  18. The common inhalation anesthetic isoflurane induces caspase activation and increases amyloid beta-protein level in vivo.

    Science.gov (United States)

    Xie, Zhongcong; Culley, Deborah J; Dong, Yuanlin; Zhang, Guohua; Zhang, Bin; Moir, Robert D; Frosch, Matthew P; Crosby, Gregory; Tanzi, Rudolph E

    2008-12-01

    An estimated 200 million patients worldwide have surgery each year. Anesthesia and surgery have been reported to facilitate emergence of Alzheimer's disease. The commonly used inhalation anesthetic isoflurane has previously been reported to induce apoptosis, and to increase levels and aggregation of Alzheimer's disease-associated amyloid beta-protein (Abeta) in cultured cells. However, the in vivo relevance has not been addressed. We therefore set out to determine effects of isoflurane on caspase activation and levels of beta-site amyloid precursor protein-cleaving enzyme (BACE) and Abeta in naive mice, using Western blot, immunohistochemistry, and reverse transcriptase polymerase chain reaction. Here we show for the first time that a clinically relevant isoflurane anesthesia (1.4% isoflurane for 2 hours) leads to caspase activation and modest increases in levels of BACE 6 hours after anesthesia in mouse brain. Isoflurane anesthesia induces caspase activation, and increases levels of BACE and Abeta up to 24 hours after anesthesia. Isoflurane may increase BACE levels by reducing BACE degradation. Moreover, the Abeta aggregation inhibitor, clioquinol, was able to attenuate isoflurane-induced caspase-3 activation in vivo. Given that transient insults to brain may lead to long-term brain damage, these findings suggest that isoflurane may promote Alzheimer's disease neuropathogenesis and, as such, have implications for use of isoflurane in humans, pending human study confirmation.

  19. Insulin Resistance as a Link between Amyloid-Beta and Tau Pathologies in Alzheimer’s Disease

    Directory of Open Access Journals (Sweden)

    Roger J. Mullins

    2017-05-01

    Full Text Available Current hypotheses and theories regarding the pathogenesis of Alzheimer’s disease (AD heavily implicate brain insulin resistance (IR as a key factor. Despite the many well-validated metrics for systemic IR, the absence of biomarkers for brain-specific IR represents a translational gap that has hindered its study in living humans. In our lab, we have been working to develop biomarkers that reflect the common mechanisms of brain IR and AD that may be used to follow their engagement by experimental treatments. We present two promising biomarkers for brain IR in AD: insulin cascade mediators probed in extracellular vesicles (EVs enriched for neuronal origin, and two-dimensional magnetic resonance spectroscopy (MRS measures of brain glucose. As further evidence for a fundamental link between brain IR and AD, we provide a novel analysis demonstrating the close spatial correlation between brain expression of genes implicated in IR (using Allen Human Brain Atlas data and tau and beta-amyloid pathologies. We proceed to propose the bold hypotheses that baseline differences in the metabolic reliance on glycolysis, and the expression of glucose transporters (GLUT and insulin signaling genes determine the vulnerability of different brain regions to Tau and/or Amyloid beta (Aβ pathology, and that IR is a critical link between these two pathologies that define AD. Lastly, we provide an overview of ongoing clinical trials that target IR as an angle to treat AD, and suggest how biomarkers may be used to evaluate treatment efficacy and target engagement.

  20. Synthetic Curcumin Analogs as Inhibitors of β -Amyloid Peptide Aggregation: Potential Therapeutic and Diagnostic Agents for Alzheimer's Disease.

    Science.gov (United States)

    Bukhari, Syed Nasir Abbas; Jantan, Ibrahim

    2015-01-01

    There is a crucial need to develop new effective drugs for Alzheimer's disease (AD) as the currently available AD treatments provide only momentary and incomplete symptomatic relief. Amongst natural products, curcumin, a major constituent of turmeric, has been intensively investigated for its neuroprotective effect against β-amyloid (Aβ)-induced toxicity in cultured neuronal cells. The ability of curcumin to attach to Aβ peptide and prevent its accumulation is attributed to its three structural characteristics such as the presence of two aromatic end groups and their co-planarity, the length and rigidity of the linker region and the substitution conformation of these aromatics. However, curcumin failed to reach adequate brain levels after oral absorption in AD clinical trials due to its low water solubility and poor oral bioavailability. A number of new curcumin analogs that mimic the active site of the compound along with analogs that mimic the curcumin anti-amyloid effect combined with anticholinesterase effect have been developed to enhance the bioavailability, pharmacokinetics, water solubility, stability at physiological conditions and delivery of curcumin. In this article, we have summarized all reported synthetic analogs of curcumin showing effects on β-amyloid and discussed their potential as therapeutic and diagnostic agents for AD.

  1. Distinguishing d- and l-aspartic and isoaspartic acids in amyloid β peptides with ultrahigh resolution ion mobility spectrometry.

    Science.gov (United States)

    Zheng, Xueyun; Deng, Liulin; Baker, Erin S; Ibrahim, Yehia M; Petyuk, Vladislav A; Smith, Richard D

    2017-07-11

    While α-linked amino acids in the l-form are exclusively utilized in mammalian protein building, β-linked and d-form amino acids also have important biological roles. Unfortunately, the structural elucidation and separation of these different amino acid types in peptides has been analytically challenging to date due to the numerous isomers present, limiting our knowledge about their existence and biological roles. Here, we utilized an ultrahigh resolution ion mobility spectrometry platform coupled with mass spectrometry (IMS-MS) to separate amyloid β (Aβ) peptides containing l-aspartic acid, d-aspartic acid, l-isoaspartic acid, and d-isoaspartic acid residues which span α- and β-linked amino acids in both d- and l-forms. The results illustrate how IMS-MS could be used to better understand age-related diseases or protein folding disorders resulting from amino acid modifications.

  2. Amyloid beta and the longest-lived rodent: the naked mole-rat as a model for natural protection from Alzheimer's disease.

    Science.gov (United States)

    Edrey, Yael H; Medina, David X; Gaczynska, Maria; Osmulski, Pawel A; Oddo, Salvatore; Caccamo, Antonella; Buffenstein, Rochelle

    2013-10-01

    Amyloid beta (Aβ) is implicated in Alzheimer's disease (AD) as an integral component of both neural toxicity and plaque formation. Brains of the longest-lived rodents, naked mole-rats (NMRs) approximately 32 years of age, had levels of Aβ similar to those of the 3xTg-AD mouse model of AD. Interestingly, there was no evidence of extracellular plaques, nor was there an age-related increase in Aβ levels in the individuals examined (2-20+ years). The NMR Aβ peptide showed greater homology to the human sequence than to the mouse sequence, differing by only 1 amino acid from the former. This subtle difference led to interspecies differences in aggregation propensity but not neurotoxicity; NMR Aβ was less prone to aggregation than human Aβ. Nevertheless, both NMR and human Aβ were equally toxic to mouse hippocampal neurons, suggesting that Aβ neurotoxicity and aggregation properties were not coupled. Understanding how NMRs acquire and tolerate high levels of Aβ with no plaque formation could provide useful insights into AD, and may elucidate protective mechanisms that delay AD progression. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Beta-Sheet-Forming, Self-Assembled Peptide Nanomaterials towards Optical, Energy, and Healthcare Applications.

    Science.gov (United States)

    Kim, Sungjin; Kim, Jae Hong; Lee, Joon Seok; Park, Chan Beum

    2015-08-12

    Peptide self-assembly is an attractive route for the synthesis of intricate organic nanostructures that possess remarkable structural variety and biocompatibility. Recent studies on peptide-based, self-assembled materials have expanded beyond the construction of high-order architectures; they are now reporting new functional materials that have application in the emerging fields such as artificial photosynthesis and rechargeable batteries. Nevertheless, there have been few reviews particularly concentrating on such versatile, emerging applications. Herein, recent advances in the synthesis of self-assembled peptide nanomaterials (e.g., cross β-sheet-based amyloid nanostructures, peptide amphiphiles) are selectively reviewed and their new applications in diverse, interdisciplinary fields are described, ranging from optics and energy storage/conversion to healthcare. The applications of peptide-based self-assembled materials in unconventional fields are also highlighted, such as photoluminescent peptide nanostructures, artificial photosynthetic peptide nanomaterials, and lithium-ion battery components. The relation of such functional materials to the rapidly progressing biomedical applications of peptide self-assembly, which include biosensors/chips and regenerative medicine, are discussed. The combination of strategies shown in these applications would further promote the discovery of novel, functional, small materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Cross-linking of cell surface amyloid precursor protein leads to increased β-amyloid peptide production in hippocampal neurons: implications for Alzheimer's disease.

    Science.gov (United States)

    Lefort, Roger; Pozueta, Julio; Shelanski, Michael

    2012-08-01

    The accumulation of the β-amyloid peptide (Aβ) in Alzheimer's disease (AD) is thought to play a causative role in triggering synaptic dysfunction in neurons, leading to their eventual demise through apoptosis. Aβ is produced and secreted upon sequential cleavage of the amyloid precursor protein (APP) by β-secretases and γ-secretases. However, while Aβ levels have been shown to be increased in the brains of AD patients, little is known about how the cleavage of APP and the subsequent generation of Aβ is influenced, or whether the cleavage process changes over time. It has been proposed that Aβ can bind APP and promote amyloidogenic processing of APP, further enhancing Aβ production. Proof of this idea has remained elusive because a clear mechanism has not been identified, and the promiscuous nature of Aβ binding complicates the task of demonstrating the idea. To work around these problems, we used an antibody-mediated approach to bind and cross-link cell-surface APP in cultured rat primary hippocampal neurons. Here we show that cross-linking of APP is sufficient to raise the levels of Aβ in viable neurons with a concomitant increase in the levels of the β-secretase BACE1. This appears to occur as a result of a sorting defect that stems from the caspase-3-mediated inactivation of a key sorting adaptor protein, namely GGA3, which prevents the lysosomal degradation of BACE1. Together, our data suggest the occurrence of a positive pathogenic feedback loop involving Aβ and APP in affected neurons possibly allowing Aβ to spread to nearby healthy neurons.

  5. Protective Effects Induced by Microwave-Assisted Aqueous Harpagophytum Extract on Rat Cortex Synaptosomes Challenged with Amyloid β-Peptide.

    Science.gov (United States)

    Ferrante, Claudio; Recinella, Lucia; Locatelli, Marcello; Guglielmi, Paolo; Secci, Daniela; Leporini, Lidia; Chiavaroli, Annalisa; Leone, Sheila; Martinotti, Sara; Brunetti, Luigi; Vacca, Michele; Menghini, Luigi; Orlando, Giustino

    2017-08-01

    Harpagophytum procumbens is a plant species that displays anti-inflammatory properties in multiple tissues. The iridoid glycosides arpagoside, harpagide, and procumbide appear to be the most therapeutically important constituents. In addition, harpagoside treatment exerted neuroprotective effects both in vitro and in vivo. Considering these findings, the aim of the present work is to explore the possible protective role of the previously described microwave-assisted aqueous extract of H. procumbens on rat hypothalamic (Hypo-E22) cells, and in rat cortex challenged with amyloid β-peptide (1-40). In this context, we assayed the protective effects induced by H. procumbens by measuring the levels of malondialdehyde, 3-hydroxykynurenine (3-HK), brain-derived neurotrophic factor, and tumor necrosis factor-α, 3-HK. Finally, we evaluated the effects of H. procumbens treatment on cortex levels of dopamine, norepinephrine, and serotonin. H. procumbens extract was well tolerated by Hypo-E22 cells and upregulated brain-derived neurotrophic factor gene expression but down-regulated tumor necrosis factor-α gene expression. In addition, the extract reduced amyloid β-peptide stimulation of malondialdehyde and 3-HK and blunted the decrease of dopamine, norepinephrine, and serotonin, in the cortex. In this context, our work supports further studies for the evaluation and confirmation of Harpagophytum in the management of the clinical symptoms related to Alzheimer's disease. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  6. AmyloidPeptide Is Needed for cGMP-Induced Long-Term Potentiation and Memory.

    Science.gov (United States)

    Palmeri, Agostino; Ricciarelli, Roberta; Gulisano, Walter; Rivera, Daniela; Rebosio, Claudia; Calcagno, Elisa; Tropea, Maria Rosaria; Conti, Silvia; Das, Utpal; Roy, Subhojit; Pronzato, Maria Adelaide; Arancio, Ottavio; Fedele, Ernesto; Puzzo, Daniela

    2017-07-19

    High levels of amyloidpeptide (Aβ) have been related to Alzheimer's disease pathogenesis. However, in the healthy brain, low physiologically relevant concentrations of Aβ are necessary for long-term potentiation (LTP) and memory. Because cGMP plays a key role in these processes, here we investigated whether the cyclic nucleotide cGMP influences Aβ levels and function during LTP and memory. We demonstrate that the increase of cGMP levels by the phosphodiesterase-5 inhibitors sildenafil and vardenafil induces a parallel release of Aβ due to a change in the approximation of amyloid precursor protein (APP) and the β-site APP cleaving enzyme 1. Moreover, electrophysiological and behavioral studies performed on animals of both sexes showed that blocking Aβ function, by using anti-murine Aβ antibodies or APP knock-out mice, prevents the cGMP-dependent enhancement of LTP and memory. Our data suggest that cGMP positively regulates Aβ levels in the healthy brain which, in turn, boosts synaptic plasticity and memory. SIGNIFICANCE STATEMENT Amyloid-β (Aβ) is a key pathogenetic factor in Alzheimer's disease. However, low concentrations of endogenous Aβ, mimicking levels of the peptide in the healthy brain, enhance hippocampal long-term potentiation (LTP) and memory. Because the second messenger cGMP exerts a central role in LTP mechanisms, here we studied whether cGMP affects Aβ levels and function during LTP. We show that cGMP enhances Aβ production by increasing the APP/BACE-1 convergence in endolysosomal compartments. Moreover, the cGMP-induced enhancement of LTP and memory was disrupted by blockade of Aβ, suggesting that the physiological effect of the cyclic nucleotide on LTP and memory is dependent upon Aβ. Copyright © 2017 the authors 0270-6474/17/376926-12$15.00/0.

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

    Directory of Open Access Journals (Sweden)

    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.

  8. Direct interaction of beta-amyloid with Na,K-ATPase as a putative regulator of the enzyme function

    Science.gov (United States)

    Petrushanko, Irina Yu.; Mitkevich, Vladimir A.; Anashkina, Anastasia A.; Adzhubei, Alexei A.; Burnysheva, Ksenia M.; Lakunina, Valentina A.; Kamanina, Yulia V.; Dergousova, Elena A.; Lopina, Olga D.; Ogunshola, Omolara O.; Bogdanova, Anna Yu.; Makarov, Alexander A.

    2016-06-01

    By maintaining the Na+ and K+ transmembrane gradient mammalian Na,K-ATPase acts as a key regulator of neuronal electrotonic properties. Na,K-ATPase has an important role in synaptic transmission and memory formation. Accumulation of beta-amyloid (Aβ) at the early stages of Alzheimer’s disease is accompanied by reduction of Na,K-ATPase functional activity. The molecular mechanism behind this phenomenon is not known. Here we show that the monomeric Aβ(1-42) forms a tight (Kd of 3 μM), enthalpy-driven equimolar complex with α1β1 Na,K-ATPase. The complex formation results in dose-dependent inhibition of the enzyme hydrolytic activity. The binding site of Aβ(1-42) is localized in the “gap” between the alpha- and beta-subunits of Na,K-ATPase, disrupting the enzyme functionality by preventing the subunits from shifting towards each other. Interaction of Na,K-ATPase with exogenous Aβ(1-42) leads to a pronounced decrease of the enzyme transport and hydrolytic activity and Src-kinase activation in neuroblastoma cells SH-SY5Y. This interaction allows regulation of Na,K-ATPase activity by short-term increase of the Aβ(1-42) level. However prolonged increase of Aβ(1-42) level under pathological conditions could lead to chronical inhibition of Na,K-ATPase and disruption of neuronal function. Taken together, our data suggest the role of beta-amyloid as a novel physiological regulator of Na,K-ATPase.

  9. Unfolding, aggregation, and seeded amyloid formation of lysine-58-cleaved beta(2)-microglobulin

    DEFF Research Database (Denmark)

    Heegaard, N.H.H.; Jørgensen, T.J.D.; Rozlosnik, N.

    2005-01-01

    . Using amide hydrogen/deuterium exchange monitored by mass spectrometry, we show that Delta K58-beta(2)m has increased unfolding rates compared to wt-beta(2)m and that unfolding is highly temperature dependent. The unfolding rate is I order of magnitude faster in Delta K58-beta(2)M than in wt-beta(2)m...... in the circulation of dialysis patients. This beta(2)M variant, Delta K58-beta(2)m, is a disulfide-linked two-chain molecule consisting of amino acid residues 1-57 and 59-99 of intact beta(2)m, and we here demonstrate and characterize its decreased conformational stability as compared to wild-type (wt) beta(2)M...

  10. Antimicrobial beta-peptides and alpha-peptoids

    DEFF Research Database (Denmark)

    Godballe, Troels; Nilsson, Line L.; Petersen, Pernille D.

    2011-01-01

    candidates is derived from naturally occurring antimicrobial peptides. However, despite promising results in early-stage clinical trials, these molecules have faced some difficulties securing FDA approval, which can be linked to their poor metabolic stability. Hence, mimetics of these antimicrobial peptides...

  11. 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

    Recent studies have demonstrated that amyloid-beta1-42 (Abeta1-42) binds to the nicotinergic alpha7 acetylcholine receptor (alpha7 nAChR) and that the application of Abeta1-42 to cells inhibits the function of the alpha7 nAChR. The in vivo consequences of the pharmacological activation of the alp...

  12. Beta-amyloid-induced cholinergic denervation correlates with enhanced nitric oxide synthase activity in rat cerebral cortex: Reversal by NMDA receptor blockade : Reversal by NMDA receptor blockade

    NARCIS (Netherlands)

    O’Mahony, S.; Harkany, T.; Ábrahám, I.; Jong, G.I. de; Varga, J.L.; Zarándi, M.; Penke, B.; Nyakas, C.; Luiten, P.G.M.; Leonard, B.E.

    1998-01-01

    Ample experimental evidence indicates that acute beta-amyloid infusion into the nucleus basalis of rats elicits abrupt degeneration of the magnocellular cholinergic neurons projecting to the cerebral cortex, In fact, involvement of a permanent Ca2+ overload, partially via N-methyl-D-aspartate (NMDA)

  13. Radioiodinated benzimidazole derivatives as single photon emission computed tomography probes for imaging of {beta}-amyloid plaques in Alzheimer's disease

    Energy Technology Data Exchange (ETDEWEB)

    Cui Mengchao [Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan); Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875 (China); Ono, Masahiro, E-mail: ono@pharm.kyoto-u.ac.j [Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan); Kimura, Hiroyuki; Kawashima, Hidekazu [Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan); Liu Boli [Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875 (China); Saji, Hideo, E-mail: hsaji@pharm.kyoto-u.ac.j [Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan)

    2011-04-15

    Five iodinated 2-phenyl-1H-benzo[d]imidazole derivatives were synthesized and evaluated as potential probes for {beta}-amyloid (A{beta}) plaques. One of the compounds, 4-(6-iodo-1H-benzo[d]imidazol-2-yl)-N,N-dimethylaniline (12), showed excellent affinity for A{beta}{sub 1-42} aggregates (K{sub i}=9.8 nM). Autoradiography with sections of postmortem Alzheimer's disease (AD) brain revealed that a radioiodinated probe [{sup 125}I]12, labeled A{beta} plaques selectively with low nonspecific binding. Biodistribution experiments with normal mice injected intravenously with [{sup 125}I]12 showed high uptake [4.14 percent injected dose per gram (% ID/g) at 2 min] into and rapid clearance (0.15% ID/g at 60 min) from the brain, which may bring about a good signal-to-noise ratio and therefore achieve highly sensitive detection of A{beta} plaques. In addition, [{sup 125}I]12 labeled amyloid plaques in vivo in an AD transgenic model. The preliminary results strongly suggest that [{sup 125}I]12 bears characteristics suitable for detecting amyloid plaques in vivo. When labeled with {sup 123}I, it may be a useful SPECT imaging agent for A{beta} plaques in the brain of living AD patients.

  14. Astrocytic expression of the Alzheimer's disease beta-secretase (BACE1) is stimulus-dependent

    DEFF Research Database (Denmark)

    Hartlage-Rübsamen, Maike; Zeitschel, Ulrike; Apelt, Jenny

    2003-01-01

    The beta-site APP-cleaving enzyme (BACE1) is a prerequisite for the generation of beta-amyloid peptides, which give rise to cerebrovascular and parenchymal beta-amyloid deposits in the brain of Alzheimer's disease patients. BACE1 is neuronally expressed in the brains of humans and experimental...... paradigms studied. In contrast, BACE1 expression by reactive astrocytes was evident in chronic but not in acute models of gliosis. Additionally, we observed BACE1-immunoreactive astrocytes in proximity to beta-amyloid plaques in the brains of aged Tg2576 mice and Alzheimer's disease patients....

  15. New Method Based on Capillary Electrophoresis with Laser-Induced Fluorescence Detection (CE-LIF) to Monitor Interaction between Nanoparticles and the AmyloidPeptide

    NARCIS (Netherlands)

    Brambilla, Davide; Verpillot, Romain; Taverna, Myriam; de Kimpe, Line; Le Droumaguet, Benjamin; Nicolas, Julien; Canovi, Mara; Gobbi, Marco; Mantegazza, Francesco; Salmona, Mario; Nicolas, Valérie; Scheper, Wiep; Couvreur, Patrick; Andrieux, Karine

    2010-01-01

    A novel application of capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was proposed to efficiently detect and monitor the interaction between polymeric nanoparticles and the β-Amyloid peptide (Aβ(1-42)), a biomarker for Alzheimer's Disease (AD), at concentrations close

  16. Classic beta-amyloid deposits cluster around large diameter blood vessels rather than capillaries in sporadic Alzheimer's disease.

    Science.gov (United States)

    Armstrong, Richard A

    2006-11-01

    Various hypotheses could explain the relationship between beta-amyloid (Abeta) deposition and the vasculature in Alzheimer's disease (AD). Amyloid deposition may reduce capillary density, affect endothelial cells of blood vessels, result in diffusion from blood vessels, or interfere with the perivascular clearance mechanism. Hence, the spatial pattern of the classic ('cored') type of Abeta deposit was studied in the upper laminae (I,II/III) of the superior frontal gyrus in nine cases of sporadic AD (SAD). Sections were immunostained with antibodies against Abeta and with collagen IV to study the relationships between the spatial distribution of the classic deposits and the blood vessel profiles. Both the classic deposits and blood vessel profiles were distributed in clusters. In all cases, there was a positive spatial correlation between the clusters of the classic deposits and the larger diameter (>10 microm) blood vessel profiles and especially the vertically penetrating arterioles. In only 1 case, was there a significant spatial correlation between the clusters of the classic deposits and the smaller diameter (upper laminae of the frontal cortex. This aggregation could result from diffusion of proteins from blood vessels or from overloading the system of perivascular clearance from the brain.

  17. Decreased rhythmic GABAergic septal activity and memory-associated theta oscillations after hippocampal amyloid-beta pathology in the rat.

    Science.gov (United States)

    Villette, Vincent; Poindessous-Jazat, Frédérique; Simon, Axelle; Léna, Clément; Roullot, Elodie; Bellessort, Brice; Epelbaum, Jacques; Dutar, Patrick; Stéphan, Aline

    2010-08-18

    The memory deficits associated with Alzheimer's disease result to a great extent from hippocampal network dysfunction. The coordination of this network relies on theta (symbol) oscillations generated in the medial septum. Here, we investigated in rats the impact of hippocampal amyloid beta (Abeta) injections on the physiological and cognitive functions that depend on the septohippocampal system. Hippocampal Abeta injections progressively impaired behavioral performances, the associated hippocampal theta power, and theta frequency response in a visuospatial recognition test. These alterations were associated with a specific reduction in the firing of the identified rhythmic bursting GABAergic neurons responsible for the propagation of the theta rhythm to the hippocampus, but without loss of medial septal neurons. Such results indicate that hippocampal Abeta treatment leads to a specific functional depression of inhibitory projection neurons of the medial septum, resulting in the functional impairment of the temporal network.

  18. A ketogenic diet reduces amyloid beta 40 and 42 in a mouse model of Alzheimer's disease

    OpenAIRE

    Van Leuven Fred; Wera Stefaan; Van der Auwera Ingrid; Henderson Samuel T

    2005-01-01

    Abstract Background Alzheimer's disease (AD) is a progressive neurodegenerative disorder that primarily strikes the elderly. Studies in both humans and animal models have linked the consumption of cholesterol and saturated fats with amyloid-β (Aβ) deposition and development of AD. Yet, these studies did not examine high fat diets in combination with reduced carbohydrate intake. Here we tested the effect of a high saturated fat/low carbohydrate diet on a transgenic mouse model of AD. Results S...

  19. Reduction of Alzheimer's disease beta-amyloid pathology in the absence of gut microbiota

    OpenAIRE

    Harach, T.; Marungruang, N.; Dutilleul, N.; Cheatham, V.; Coy, K. D. Mc; Neher, J. J.; Jucker, M.; Fåk, F.; T.; Lasser; Bolmont, T.

    2015-01-01

    Alzheimer's disease is the most common form of dementia in the western world, however there is no cure available for this devastating neurodegenerative disorder. Despite clinical and experimental evidence implicating the intestinal microbiota in a number of brain disorders, its impact on Alzheimer's disease is not known. We generated a germ-free mouse model of Alzheimer's disease and discovered a drastic reduction of cerebral Ab amyloid pathology when compared to control Alzheimer's disease a...

  20. Turn stability in beta-hairpin peptides: Investigation of peptides containing 3:5 type I G1 bulge turns.

    Science.gov (United States)

    Blandl, Tamas; Cochran, Andrea G; Skelton, Nicholas J

    2003-02-01

    The turn-forming ability of a series of three-residue sequences was investigated by substituting them into a well-characterized beta-hairpin peptide. The starting scaffold, bhpW, is a disulfide-cyclized 10-residue peptide that folds into a stable beta-hairpin with two antiparallel strands connected by a two-residue reverse turn. Substitution of the central two residues with the three-residue test sequences leads to less stable hairpins, as judged by thiol-disulfide equilibrium measurements. However, analysis of NMR parameters indicated that each molecule retains a significant folded population, and that the type of turn adopted by the three-residue sequence is the same in all cases. The solution structure of a selected peptide with a PDG turn contained an antiparallel beta-hairpin with a 3:5 type I + G1 bulge turn. Analysis of the energetic contributions of individual turn residues in the series of peptides indicates that substitution effects have significant context dependence, limiting the predictive power of individual amino acid propensities for turn formation. The most stable and least stable sequences were also substituted into a more stable disulfide-cyclized scaffold and a linear beta-hairpin scaffold. The relative stabilities remained the same, suggesting that experimental measurements in the bhpW context are a useful way to evaluate turn stability for use in protein design projects. Moreover, these scaffolds are capable of displaying a diverse set of turns, which can be exploited for the mimicry of protein loops or for generating libraries of reverse turns.

  1. The alpha7 nicotinic acetylcholine receptor-selective antagonist, methyllycaconitine, partially protects against beta-amyloid1-42 toxicity in primary neuron-enriched cultures.

    Science.gov (United States)

    Martin, Shelley E; de Fiebre, Nancy Ellen C; de Fiebre, Christopher M

    2004-10-01

    Studies have suggested that the neuroprotective actions of alpha7 nicotinic agonists arise from activation of receptors and not from the extensive desensitization which rapidly follows activation. Here, we report that the alpha7-selective nicotinic antagonist, methyllycaconitine (MLA), protects against beta-amyloid-induced neurotoxicity; whereas the alpha4beta2-selective antagonist, dihydro-beta-erythroidine, does not. These findings suggest that neuroprotective actions of alpha7-acting agents arise from receptor inhibition/desensitization and that alpha7 antagonists may be useful neuroprotective agents.

  2. 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)

    Steen Jensen, Camilla; 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...

  3. Surface Plasmon Resonance Based Biosensors for Exploring the Influence of Alkaloids on Aggregation of AmyloidPeptide

    Directory of Open Access Journals (Sweden)

    Hanna Radecka

    2011-04-01

    Full Text Available The main objective of the presented study was the development of a simple analytical tool for exploring the influence of naturally occurring compounds on the aggregation of amyloidpeptide (Aβ40 in order to find potential anti-neurodegenerative drugs. The gold discs used for surface plasmon resonance (SPR measurements were modified with thioaliphatic acid. The surface functionalized with carboxylic groups was used for covalent attaching of Aβ40 probe by creation of amide bonds in the presence of EDC/NHS. The modified SPR gold discs were used for exploring the Aβ40 aggregation process in the presence of selected alkaloids: arecoline hydrobromide, pseudopelletierine hydrochloride, trigonelline hydrochloride and α-lobeline hydrochloride. The obtained results were discussed with other parameters which govern the phenomenon studied such as lipophilicity/ hydrophilicy and Aβ40-alkaloid association constants.

  4. Dynamic membrane interactions of antibacterial and antifungal biomolecules, and amyloid peptides, revealed by solid-state NMR spectroscopy.

    Science.gov (United States)

    Naito, Akira; Matsumori, Nobuaki; Ramamoorthy, Ayyalusamy

    2018-02-01

    A variety of biomolecules acting on the cell membrane folds into a biologically active structure in the membrane environment. It is, therefore, important to determine the structures and dynamics of such biomolecules in a membrane environment. While several biophysical techniques are used to obtain low-resolution information, solid-state NMR spectroscopy is one of the most powerful means for determining the structure and dynamics of membrane bound biomolecules such as antibacterial biomolecules and amyloidogenic proteins; unlike X-ray crystallography and solution NMR spectroscopy, applications of solid-state NMR spectroscopy are not limited by non-crystalline, non-soluble nature or molecular size of membrane-associated biomolecules. This review article focuses on the applications of solid-state NMR techniques to study a few selected antibacterial and amyloid peptides. Solid-state NMR studies revealing the membrane inserted bent α-helical structure associated with the hemolytic activity of bee venom melittin and the chemical shift oscillation analysis used to determine the transmembrane structure (with α-helix and 3 10 -helix in the N- and C-termini, respectively) of antibiotic peptide alamethicin are discussed in detail. Oligomerization of an amyloidogenic islet amyloid polypeptide (IAPP, or also known as amylin) resulting from its aggregation in a membrane environment, molecular interactions of the antifungal natural product amphotericin B with ergosterol in lipid bilayers, and the mechanism of lipid raft formation by sphingomyelin studied using solid state NMR methods are also discussed in this review article. This article is part of a Special Issue entitled "Biophysical Exploration of Dynamical Ordering of Biomolecular Systems" edited by Dr. Koichi Kato. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. The interaction of beta 2-microglobulin (beta 2m) with mouse class I major histocompatibility antigens and its ability to support peptide binding. A comparison of human and mouse beta 2m

    DEFF Research Database (Denmark)

    Pedersen, L O; Stryhn, A; Holter, T L

    1995-01-01

    of class I molecules are involved in peptide binding, whereas most of class I molecules are involved in beta 2m binding. We propose that mouse beta 2m interacts with the minor peptide binding (i.e. the "empty") fraction with a lower affinity than human beta 2m does, whereas mouse and human beta 2m interact......The function of major histocompatibility complex (MHC) class I molecules is to sample peptides derived from intracellular proteins and to present these peptides to CD8+ cytotoxic T lymphocytes. In this paper, biochemical assays addressing MHC class I binding of both peptide and beta 2-microglobulin...... (beta 2m) have been used to examine the assembly of the trimolecular MHC class I/beta 2m/peptide complex. Recombinant human beta 2m and mouse beta 2ma have been generated to compare the binding of the two beta 2m to mouse class I. It is frequently assumed that human beta 2m binds to mouse class I heavy...

  6. Familial Alzheimer's disease mutations in presenilin 1 do not alter levels of the secreted amyloid-beta protein precursor generated by beta-secretase cleavage.

    Science.gov (United States)

    Zhang, Can; Browne, Andrew; Kim, Doo Yeon; Tanzi, Rudolph E

    2010-02-01

    Alzheimer's disease (AD) is an insidious and progressive disease with a genetically complex and heterogenous etiology. More than 200 fully penetrant mutations in the amyloid beta-protein precursor (APP), presenilin 1 (or PSEN1), and presenilin 2 (PSEN2) have been linked to early-onset familial AD (FAD). 177 PSEN1 FAD mutations have been identified so far and account for more than approximately 80% of all FAD mutations. All PSEN1 FAD mutations can increase the Abeta42:Abeta40 ratio with seemingly different and incompletely understood mechanisms. A recent study has shown that the 286 amino acid N-terminal fragment of APP (N-APP), a proteolytic product of beta-secretase-derived secreted form of APP (sAPPbeta), could bind the death receptor, DR6, and lead to neurodegeneration. Here we asked whether PSEN1 FAD mutations lead to neurodegeneration by modulating sAPPbeta levels. All four different PSEN1 FAD mutations tested (in three mammalian cell lines) did not alter sAPPbeta levels. Therefore PS1 mutations do not appear to contribute to AD pathogenesis via altered production of sAPPbeta.

  7. Involvement of insulin-degrading enzyme in insulin- and atrial natriuretic peptide-sensitive internalization of amyloidpeptide in mouse brain capillary endothelial cells.

    Science.gov (United States)

    Ito, Shingo; Ohtsuki, Sumio; Murata, Sho; Katsukura, Yuki; Suzuki, Hiroya; Funaki, Miho; Tachikawa, Masanori; Terasaki, Tetsuya

    2014-01-01

    Cerebral clearance of amyloidpeptide (Aβ), which is implicated in Alzheimer's disease, involves elimination across the blood-brain barrier (BBB), and we previously showed that an insulin-sensitive process is involved in the case of Aβ1-40. The purpose of this study was to clarify the molecular mechanism of the insulin-sensitive Aβ1-40 elimination across mouse BBB. An in vivo cerebral microinjection study demonstrated that [125I]hAβ1-40 elimination from mouse brain was inhibited by human natriuretic peptide (hANP), and [125I]hANP elimination was inhibited by hAβ1-40, suggesting that hAβ1-40 and hANP share a common elimination process. Internalization of [125I]hAβ1-40 into cultured mouse brain capillary endothelial cells (TM-BBB4) was significantly inhibited by either insulin, hANP, other natriuretic peptides or insulin-degrading enzyme (IDE) inhibitors, but was not inhibited by phosphoramidon or thiorphan. Although we have reported the involvement of natriuretic peptide receptor C (Npr-C) in hANP internalization, cells stably expressing Npr-C internalized [125I]hANP but not [125I]hAβ1-40, suggesting that there is no direct interaction between Npr-C and hAβ1-40. IDE was detected in plasma membrane of TM-BBB4 cells, and internalization of [125I]hAβ1-40 by TM-BBB4 cells was reduced by IDE-targeted siRNAs. We conclude that elimination of hAβ1-40 from mouse brain across the BBB involves an insulin- and ANP-sensitive process, mediated by IDE expressed in brain capillary endothelial cells.

  8. Three-residue turns in alpha/beta-peptides and their application in the design of tertiary structures.

    Science.gov (United States)

    Sharma, Gangavaram V M; Nagendar, Pendem; Ramakrishna, Kallaganti V S; Chandramouli, Nagula; Choudhary, Madavi; Kunwar, Ajit C

    2008-06-02

    A new three-residue turn was serendipitously discovered in alpha/beta hybrid peptides derived from alternating C-linked carbo-beta-amino acids (beta-Caa) and L-Ala residues. The three-residue beta-alpha-beta turn at the C termini, nucleated by a helix at the N termini, resulted in helix-turn (HT) supersecondary structures in these peptides. The turn in the HT motif is stabilized by two H bonds-CO(i-2)-NH(i), with a seven-membered pseudoring (gamma turn) in the backward direction, and NH(i-2)-CO(i), with a 13-membered pseudoring in the forward direction (i being the last residue)--at the C termini. The study was extended to generalize the new three-residue turn (beta-alpha-beta) by using different alpha- and beta-amino acids. Furthermore, the HT motifs were efficiently converted, by an extension with helical oligomers at the C termini, into peptides with novel helix-turn-helix (HTH) tertiary structures. However, this resulted in the destabilization of the beta-alpha-beta turn with the concomitant nucleation of another three-residue turn, alpha-beta-beta, which is stabilized by 11- and 15-membered bifurcated H bonds. Extensive NMR spectroscopic studies were carried out to delineate the secondary and tertiary structures in these peptides, which are further supported by molecular dynamics (MD) investigations.

  9. Milk bioactive peptides and beta-casomorphins induce mucus release in rat jejunum.

    Science.gov (United States)

    Trompette, Aurélien; Claustre, Jean; Caillon, Fabienne; Jourdan, Gérard; Chayvialle, Jean Alain; Plaisancié, Pascale

    2003-11-01

    Intestinal mucus is critically involved in the protection of the mucosa. An enzymatic casein hydrolysate and beta-casomorphin-7, a mu-opioid peptide generated in the intestine during bovine casein digestion, markedly induce mucus discharge. Because shorter mu-opioid peptides have been described, the effects of the opioid peptides in casein, beta-casomorphin-7, -6, -4, -4NH2 and -3, and of opioid neuropeptides met-enkephalin, dynorphin A and (D-Ala2,N-Me-Phe4,glycinol5)enkephalin (DAMGO) on intestinal mucus secretion were investigated. The experiments were conducted with isolated perfused rat jejunum. Mucus secretion under the influence of beta-casomorphins and opioid neuropeptides administered intraluminally or intra-arterially was evaluated using an ELISA for rat intestinal mucus. Luminal administration of beta-casomorphin-7 (1.2 x 10(-4) mol/L) provoked a mucus discharge (500% of controls) that was inhibited by naloxone, a specific opiate receptor antagonist. Luminal beta-casomorphin-6, -4 and -4NH2 did not modify basal mucus secretion, whereas intra-arterial administration of beta-casomorphin-4 (1.2 x 10(-6) mol/L) induced a mucus discharge. In contrast, intra-arterial administration of the nonopioid peptide beta-casomorphin-3 did not release mucus. Among the opioid neuropeptides, intra-arterial infusion of Met-enkephalin or dynorphin-A did not provoke mucus secretion. In contrast, beta-endorphin (1.2 x 10(-8) to 1.2 x 10(-6) mol/L) induced a dose-dependent release of mucus (maximal response at 500% of controls). DAMGO (1.2 x 10(-6) mol/L), a mu-receptor agonist, also evoked a potent mucus discharge. Our findings suggest that mu-opioid neuropeptides, as well as beta-casomorphins after absorption, modulate intestinal mucus discharge. Milk opioid-derived peptides may thus be involved in defense against noxious agents and could have dietary and health applications.

  10. Protective role of rosmarinic acid on amyloid beta 42-induced echoic memory decline: Implication of oxidative stress and cholinergic impairment.

    Science.gov (United States)

    Kantar Gok, Deniz; Hidisoglu, Enis; Ocak, Guzide Ayse; Er, Hakan; Acun, Alev Duygu; Yargıcoglu, Piraye

    2018-04-13

    In the present study, we examined whether rosmarinic acid (RA) reverses amyloid β (Aβ) induced reductions in antioxidant defense, lipid peroxidation, cholinergic damage as well as the central auditory deficits. For this purpose, Wistar rats were randomly divided into four groups; Sham(S), Sham + RA (SR), Aβ42 peptide (Aβ) and Aβ42 peptide + RA (AβR) groups. Rat model of Alzheimer was established by bilateral injection of Aβ42 peptide (2,2 nmol/10 μl) into the lateral ventricles. RA (50 mg/kg, daily) was administered orally by gavage for 14 days after intracerebroventricular injection. At the end of the experimental period, we recorded the auditory event related potentials (AERPs) and mismatch negativity (MMN) response to assess auditory functions followed by histological and biochemical analysis. Aβ42 injection led to a significant increase in the levels of thiobarbituric acid reactive substances (TBARS) and 4-Hydroxy-2-nonenal (4-HNE) but decreased the activity of antioxidant enzymes (SOD, CAT, GSH-Px) and glutathione levels. Moreover, Aβ42 injection resulted in a reduction in the acetylcholine content and acetylcholine esterase activity. RA treatment prevented the observed alterations in the AβR group. Furthermore, RA attenuated the increased Aβ staining and astrocyte activation. We also found that Aβ42 injection decreased the MMN response and theta power/coherence of AERPs, suggesting an impairing effect on auditory discrimination and echoic memory processes. RA treatment reversed the Aβ42 related alterations in AERP parameters. In conclusion, our study demonstrates that RA prevented Aβ-induced antioxidant-oxidant imbalance and cholinergic damage, which may contribute to the improvement of neural network dynamics of auditory processes in this rat model. Copyright © 2018. Published by Elsevier Ltd.

  11. Impact of amyloid-beta changes on cognitive outcomes in Alzheimer's disease: analysis of clinical trials using a quantitative systems pharmacology model.

    Science.gov (United States)

    Geerts, Hugo; Spiros, Athan; Roberts, Patrick

    2018-02-02

    Despite a tremendous amount of information on the role of amyloid in Alzheimer's disease (AD), almost all clinical trials testing this hypothesis have failed to generate clinically relevant cognitive effects. We present an advanced mechanism-based and biophysically realistic quantitative systems pharmacology computer model of an Alzheimer-type neuronal cortical network that has been calibrated with Alzheimer Disease Assessment Scale, cognitive subscale (ADAS-Cog) readouts from historical clinical trials and simulated the differential impact of amyloid-beta (Aβ40 and Aβ42) oligomers on glutamate and nicotinic neurotransmission. Preclinical data suggest a beneficial effect of shorter Aβ forms within a limited dose range. Such a beneficial effect of Aβ40 on glutamate neurotransmission in human patients is absolutely necessary to reproduce clinical data on the ADAS-Cog in minimal cognitive impairment (MCI) patients with and without amyloid load, the effect of APOE genotype effect on the slope of the cognitive trajectory over time in placebo AD patients and higher sensitivity to cholinergic manipulation with scopolamine associated with higher Aβ in MCI subjects. We further derive a relationship between units of Aβ load in our model and the standard uptake value ratio from amyloid imaging. When introducing the documented clinical pharmacodynamic effects on Aβ levels for various amyloid-related clinical interventions in patients with low Aβ baseline, the platform predicts an overall significant worsening for passive vaccination with solanezumab, beta-secretase inhibitor verubecestat and gamma-secretase inhibitor semagacestat. In contrast, all three interventions improved cognition in subjects with moderate to high baseline Aβ levels, with verubecestat anticipated to have the greatest effect (around ADAS-Cog value 1.5 points), solanezumab the lowest (0.8 ADAS-Cog value points) and semagacestat in between. This could explain the success of many amyloid

  12. Environmental enrichment and exercise are better than social enrichment to reduce memory deficits in amyloid beta neurotoxicity.

    Science.gov (United States)

    Prado Lima, Mariza G; Schimidt, Helen L; Garcia, Alexandre; Daré, Letícia R; Carpes, Felipe P; Izquierdo, Ivan; Mello-Carpes, Pâmela B

    2018-03-06

    Recently, nongenetic animal models to study the onset and development of Alzheimer's disease (AD) have appeared, such as the intrahippocampal infusion of peptides present in Alzheimer amyloid plaques [i.e., amyloid-β (Aβ)]. Nonpharmacological approaches to AD treatment also have been advanced recently, which involve combinations of behavioral interventions whose specific effects are often difficult to determine. Here we isolate the neuroprotective effects of three of these interventions-environmental enrichment (EE), anaerobic physical exercise (AnPE), and social enrichment (SE)-on Aβ-induced oxidative stress and on impairments in learning and memory induced by Aβ. Wistar rats were submitted to 8 wk of EE, AnPE, or SE, followed by Aβ infusion in the dorsal hippocampus. Short-term memory (STM) and long-term memory (LTM) of object recognition (OR) and social recognition (SR) were evaluated. Biochemical assays determined hippocampal oxidative status: reactive oxygen species, lipid peroxidation by thiobarbituric acid reactive substance (TBARS) test, and total antioxidant capacity by ferric reducing/antioxidant power (FRAP), as well as acetylcholinesterase activity. Aβ infusion resulted in memory deficits and hippocampal oxidative damage. EE and AnPE prevented all memory deficits (STM and LTM of OR and SR) and lipid peroxidation (i.e., TBARS). SE prevented only the SR memory deficits and the decrease of total antioxidant capacity decrease (i.e., FRAP). Traditionally, findings obtained with EE protocols do not allow discrimination of the roles of the three individual factors involved. Here we demonstrate that EE and physical exercise have better neuroprotective effects than SE in memory deficits related to Aβ neurotoxicity in the AD model tested.

  13. Designed beta-boomerang antiendotoxic and antimicrobial peptides: structures and activities in lipopolysaccharide.

    Science.gov (United States)

    Bhunia, Anirban; Mohanram, Harini; Domadia, Prerna N; Torres, Jaume; Bhattacharjya, Surajit

    2009-08-14

    Lipopolysaccharide (LPS), an integral part of the outer membrane of Gram-negative bacteria, is involved in a variety of biological processes including inflammation, septic shock, and resistance to host-defense molecules. LPS also provides an environment for folding of outer membrane proteins. In this work, we describe the structure-activity correlation of a series of 12-residue peptides in LPS. NMR structures of the peptides derived in complex with LPS reveal boomerang-like beta-strand conformations that are stabilized by intimate packing between the two aromatic residues located at the 4 and 9 positions. This structural feature renders these peptides with a high ability to neutralize endotoxicity, >80% at 10 nM concentration, of LPS. Replacements of these aromatic residues either with Ala or with Leu destabilizes the boomerang structure with the concomitant loss of antiendotoxic and antimicrobial activities. Furthermore, the aromatic packing stabilizing the beta-boomerang structure in LPS is found to be maintained even in a truncated octapeptide, defining a structured LPS binding motif. The mode of action of the active designed peptides correlates well with their ability to perturb LPS micelle structures. Fourier transform infrared spectroscopy studies of the peptides delineate beta-type conformations and immobilization of phosphate head groups of LPS. Trp fluorescence studies demonstrated selective interactions with LPS and the depth of insertion into the LPS bilayer. Our results demonstrate the requirement of LPS-specific structures of peptides for endotoxin neutralizations. In addition, we propose that structures of these peptides may be employed to design proteins for the outer membrane.

  14. Voluntary Exercise Promotes Glymphatic Clearance of Amyloid Beta and Reduces the Activation of Astrocytes and Microglia in Aged Mice.

    Science.gov (United States)

    He, Xiao-Fei; Liu, Dong-Xu; Zhang, Qun; Liang, Feng-Ying; Dai, Guang-Yan; Zeng, Jin-Sheng; Pei, Zhong; Xu, Guang-Qing; Lan, Yue

    2017-01-01

    Age is characterized by chronic inflammation, leading to synaptic dysfunction and dementia because the clearance of protein waste is reduced. The clearance of proteins depends partly on the permeation of the blood-brain barrier (BBB) or on the exchange of water and soluble contents between the cerebrospinal fluid (CSF) and the interstitial fluid (ISF). A wealth of evidence indicates that physical exercise improves memory and cognition in neurodegenerative diseases during aging, such as Alzheimer's disease (AD), but the influence of physical training on glymphatic clearance, BBB permeability and neuroinflammation remains unclear. In this study, glymphatic clearance and BBB permeability were evaluated in aged mice using in vivo two-photon imaging. The mice performed voluntary wheel running exercise and their water-maze cognition was assessed; the expression of the astrocytic water channel aquaporin 4 (AQP4), astrocyte and microglial activation, and the accumulation of amyloid beta (Aβ) were evaluated with immunofluorescence or an enzyme-linked immunosorbent assay (ELISA); synaptic function was investigated with Thy1 -green fluorescent protein (GFP) transgenic mice and immunofluorescent staining. Voluntary wheel running significantly improved water-maze cognition in the aged mice, accelerated the efficiency of glymphatic clearance, but which did not affect BBB permeability. The numbers of activated astrocytes and microglia decreased, AQP4 expression increased, and the distribution of astrocytic AQP4 was rearranged. Aβ accumulation decreased, whereas dendrites, dendritic spines and postsynaptic density protein (PSD95) increased. Our study suggests that voluntary wheel running accelerated glymphatic clearance but not BBB permeation, improved astrocytic AQP4 expression and polarization, attenuated the accumulation of amyloid plaques and neuroinflammation, and ultimately protected mice against synaptic dysfunction and a decline in spatial cognition. These data suggest

  15. Voluntary Exercise Promotes Glymphatic Clearance of Amyloid Beta and Reduces the Activation of Astrocytes and Microglia in Aged Mice

    Directory of Open Access Journals (Sweden)

    Xiao-fei He

    2017-05-01

    Full Text Available Age is characterized by chronic inflammation, leading to synaptic dysfunction and dementia because the clearance of protein waste is reduced. The clearance of proteins depends partly on the permeation of the blood–brain barrier (BBB or on the exchange of water and soluble contents between the cerebrospinal fluid (CSF and the interstitial fluid (ISF. A wealth of evidence indicates that physical exercise improves memory and cognition in neurodegenerative diseases during aging, such as Alzheimer’s disease (AD, but the influence of physical training on glymphatic clearance, BBB permeability and neuroinflammation remains unclear. In this study, glymphatic clearance and BBB permeability were evaluated in aged mice using in vivo two-photon imaging. The mice performed voluntary wheel running exercise and their water-maze cognition was assessed; the expression of the astrocytic water channel aquaporin 4 (AQP4, astrocyte and microglial activation, and the accumulation of amyloid beta (Aβ were evaluated with immunofluorescence or an enzyme-linked immunosorbent assay (ELISA; synaptic function was investigated with Thy1–green fluorescent protein (GFP transgenic mice and immunofluorescent staining. Voluntary wheel running significantly improved water-maze cognition in the aged mice, accelerated the efficiency of glymphatic clearance, but which did not affect BBB permeability. The numbers of activated astrocytes and microglia decreased, AQP4 expression increased, and the distribution of astrocytic AQP4 was rearranged. Aβ accumulation decreased, whereas dendrites, dendritic spines and postsynaptic density protein (PSD95 increased. Our study suggests that voluntary wheel running accelerated glymphatic clearance but not BBB permeation, improved astrocytic AQP4 expression and polarization, attenuated the accumulation of amyloid plaques and neuroinflammation, and ultimately protected mice against synaptic dysfunction and a decline in spatial cognition

  16. Cerebral amyloid-beta protein accumulation with aging in cotton-top tamarins: a model of early Alzheimer's disease?

    Science.gov (United States)

    Lemere, Cynthia A; Oh, Jiwon; Stanish, Heather A; Peng, Ying; Pepivani, Imelda; Fagan, Anne M; Yamaguchi, Haruyasu; Westmoreland, Susan V; Mansfield, Keith G

    2008-04-01

    Alzheimer's disease (AD) is the most common progressive form of dementia in the elderly. Two major neuropathological hallmarks of AD include cerebral deposition of amyloid-beta protein (Abeta) into plaques and blood vessels, and the presence of neurofibrillary tangles in brain. In addition, activated microglia and reactive astrocytes are often associated with plaques and tangles. Numerous other proteins are associated with plaques in human AD brain, including Apo E and ubiquitin. The amyloid precursor protein and its shorter fragment, Abeta, are homologous between humans and non-human primates. Cerebral Abeta deposition has been reported previously for rhesus monkeys, vervets, squirrel monkeys, marmosets, lemurs, cynomologous monkeys, chimpanzees, and orangutans. Here we report, for the first time, age-related neuropathological changes in cotton-top tamarins (CTT, Saguinus oedipus), an endangered non-human primate native to the rainforests of Colombia and Costa Rica. Typical lifespan is 13-14 years of age in the wild and 15-20+ years in captivity. We performed detailed immunohistochemical analyses of Abeta deposition and associated pathogenesis in archived brain sections from 36 tamarins ranging in age from 6-21 years. Abeta plaque deposition was observed in 16 of the 20 oldest tamarins (>12 years). Plaques contained mainly Abeta42, and in the oldest animals, were associated with reactive astrocytes, activated microglia, Apo E, and ubiquitin-positive dystrophic neurites, similar to human plaques. Vascular Abeta was detected in 14 of the 20 aged tamarins; Abeta42 preceded Abeta40 deposition. Phospho-tau labeled dystrophic neurites and tangles, typically present in human AD, were absent in the tamarins. In conclusion, tamarins may represent a model of early AD pathology.

  17. Development and validation of dried matrix spot sampling for the quantitative determination of amyloid β peptides in cerebrospinal fluid.

    Science.gov (United States)

    Delaby, Constance; Gabelle, Audrey; Meynier, Philippe; Loubiere, Vincent; Vialaret, Jérôme; Tiers, Laurent; Ducos, Jacques; Hirtz, Christophe; Lehmann, Sylvain

    2014-05-01

    The use of dried blood spots on filter paper is well documented as an affordable and practical alternative to classical venous sampling for various clinical needs. This technique has indeed many advantages in terms of collection, biological safety, storage, and shipment. Amyloid β (Aβ) peptides are useful cerebrospinal fluid (CSF) biomarkers for Alzheimer disease diagnosis. However, Aβ determination is hindered by preanalytical difficulties in terms of sample collection and stability in tubes. We compared the quantification of Aβ peptides (1-40, 1-42, and 1-38) by simplex and multiplex ELISA, following either a standard operator method (liquid direct quantification) or after spotting CSF onto dried matrix paper card. The use of dried matrix spot (DMS) overcame preanalytical problems and allowed the determination of Aβ concentrations that were highly commutable (Bland-Altman) with those obtained using CSF in classical tubes. Moreover, we found a positive and significant correlation (r2=0.83, Pearson coefficient p=0.0329) between the two approaches. This new DMS method for CSF represents an interesting alternative that increases the quality and efficiency in preanalytics. This should enable the better exploitation of Aβ analytes for Alzheimer's diagnosis.

  18. Cholinergic Neurons - Keeping Check on Amyloid beta in the Cerebral Cortex

    Directory of Open Access Journals (Sweden)

    Saak V. Ovsepian

    2013-12-01

    Full Text Available The physiological relevance of the uptake of ligands with no apparent trophic functions via the p75 neurotrophin receptor (p75NTR remains unclear. Herein, we propose a homeostatic role for this in clearance of amyloid β (Aβ in the brain. We hypothesize that uptake of Aβ in conjunction with p75NTR followed by its degradation in lysosomes endows cholinergic basalo-cortical projections enriched in this receptor a facility for maintaining physiological levels of Aβ in target areas. Thus, in addition to the diffuse modulator influence and channeling of extra-thalamic signals, cholinergic innervations could supply the cerebral cortex with an elaborate system for Aβ drainage. Interpreting the emerging relationship of new molecular data with established role of cholinergic modulator system in regulating cortical network dynamics should provide new insights into the brain physiology and mechanisms of neuro-degenerative diseases.

  19. Syntheses and characterization of novel oxoisoaporphine derivatives as dual inhibitors for cholinesterases and amyloid beta aggregation.

    Science.gov (United States)

    Li, Yan-Ping; Ning, Fang-Xian; Yang, Meng-Bi; Li, Yong-Cheng; Nie, Min-Hua; Ou, Tian-Miao; Tan, Jia-Heng; Huang, Shi-Liang; Li, Ding; Gu, Lian-Quan; Huang, Zhi-Shu

    2011-05-01

    A series of 3-substituted (5c-5f, 6c-6f) and 4-substituted (10a-10g) oxoisoaporphine derivatives were synthesized. It was found that all these synthetic compounds had IC50 values at micro or nano molar range for cholinesterase inhibition, and most of them could inhibit amyloid β (Aβ) self-induced aggregation with inhibition ratio from 31.8% to 57.6%. The structure-activity relationship studies revealed that the derivatives with higher selectivity on AChE also showed better inhibition on Aβ self-induced aggregation. The results from cell toxicity study indicated that most quaternary methiodide salts had higher IC50 values than the corresponding non-quaternary compounds. This study provided potentially important information for further development of oxoisoaporphine derivatives as lead compounds for the treatment of Alzheimer's disease. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  20. Synergistic effects of high fat feeding and apolipoprotein E deletion on enterocytic amyloid-beta abundance

    Directory of Open Access Journals (Sweden)

    Dhaliwal Satvinder S

    2008-04-01

    Full Text Available Abstract Background Amyloid-β (Aβ, a key protein found in amyloid plaques of subjects with Alzheimer's disease is expressed in the absorptive epithelial cells of the small intestine. Ingestion of saturated fat significantly enhances enterocytic Aβ abundance whereas fasting abolishes expression. Apolipoprotein (apo E has been shown to directly modulate Aβ biogenesis in liver and neuronal cells but it's effect in enterocytes is not known. In addition, apo E modulates villi length, which may indirectly modulate Aβ as a consequence of differences in lipid absorption. This study compared Aβ abundance and villi length in wild-type (WT and apo E knockout (KO mice maintained on either a low-fat or high-fat diet. Wild-type C57BL/6J and apo E KO mice were randomised for six-months to a diet containing either 4% (w/w unsaturated fats, or chow comprising 16% saturated fats and 1% cholesterol. Quantitative immunohistochemistry was used to assess Aβ abundance in small intestinal enterocytes. Apo E KO mice given the low-fat diet had similar enterocytic Aβ abundance compared to WT controls. Results The saturated fat diet substantially increased enterocytic Aβ in WT and in apo E KO mice, however the effect was greater in the latter. Villi height was significantly greater in apo E KO mice than for WT controls when given the low-fat diet. However, WT mice had comparable villi length to apo E KO when fed the saturated fat and cholesterol enriched diet. There was no effect of the high-fat diet on villi length in apo E KO mice. Conclusion The findings of this study are consistent with the notion that lipid substrate availability modulates enterocytic Aβ. Apo E may influence enterocytic lipid availability by modulating absorptive capacity.

  1. Sphingolipid Metabolism Correlates with Cerebrospinal Fluid Beta Amyloid Levels in Alzheimer’s Disease

    Science.gov (United States)

    Fonteh, Alfred N.; Ormseth, Cora; Chiang, Jiarong; Cipolla, Matthew; Arakaki, Xianghong; Harrington, Michael G.

    2015-01-01

    Sphingolipids are important in many brain functions but their role in Alzheimer’s disease (AD) is not completely defined. A major limit is availability of fresh brain tissue with defined AD pathology. The discovery that cerebrospinal fluid (CSF) contains abundant nanoparticles that include synaptic vesicles and large dense core vesicles offer an accessible sample to study these organelles, while the supernatant fluid allows study of brain interstitial metabolism. Our objective was to characterize sphingolipids in nanoparticles representative of membrane vesicle metabolism, and in supernatant fluid representative of interstitial metabolism from study participants with varying levels of cognitive dysfunction. We recently described the recruitment, diagnosis, and CSF collection from cognitively normal or impaired study participants. Using liquid chromatography tandem mass spectrometry, we report that cognitively normal participants had measureable levels of sphingomyelin, ceramide, and dihydroceramide species, but that their distribution differed between nanoparticles and supernatant fluid, and further differed in those with cognitive impairment. In CSF from AD compared with cognitively normal participants: a) total sphingomyelin levels were lower in nanoparticles and supernatant fluid; b) levels of ceramide species were lower in nanoparticles and higher in supernatant fluid; c) three sphingomyelin species were reduced in the nanoparticle fraction. Moreover, three sphingomyelin species in the nanoparticle fraction were lower in mild cognitive impairment compared with cognitively normal participants. The activity of acid, but not neutral sphingomyelinase was significantly reduced in the CSF from AD participants. The reduction in acid sphingomylinase in CSF from AD participants was independent of depression and psychotropic medications. Acid sphingomyelinase activity positively correlated with amyloid β42 concentration in CSF from cognitively normal but not impaired

  2. Sphingolipid metabolism correlates with cerebrospinal fluid Beta amyloid levels in Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Alfred N Fonteh

    Full Text Available Sphingolipids are important in many brain functions but their role in Alzheimer's disease (AD is not completely defined. A major limit is availability of fresh brain tissue with defined AD pathology. The discovery that cerebrospinal fluid (CSF contains abundant nanoparticles that include synaptic vesicles and large dense core vesicles offer an accessible sample to study these organelles, while the supernatant fluid allows study of brain interstitial metabolism. Our objective was to characterize sphingolipids in nanoparticles representative of membrane vesicle metabolism, and in supernatant fluid representative of interstitial metabolism from study participants with varying levels of cognitive dysfunction. We recently described the recruitment, diagnosis, and CSF collection from cognitively normal or impaired study participants. Using liquid chromatography tandem mass spectrometry, we report that cognitively normal participants had measureable levels of sphingomyelin, ceramide, and dihydroceramide species, but that their distribution differed between nanoparticles and supernatant fluid, and further differed in those with cognitive impairment. In CSF from AD compared with cognitively normal participants: a total sphingomyelin levels were lower in nanoparticles and supernatant fluid; b levels of ceramide species were lower in nanoparticles and higher in supernatant fluid; c three sphingomyelin species were reduced in the nanoparticle fraction. Moreover, three sphingomyelin species in the nanoparticle fraction were lower in mild cognitive impairment compared with cognitively normal participants. The activity of acid, but not neutral sphingomyelinase was significantly reduced in the CSF from AD participants. The reduction in acid sphingomylinase in CSF from AD participants was independent of depression and psychotropic medications. Acid sphingomyelinase activity positively correlated with amyloid β42 concentration in CSF from cognitively normal but

  3. Chronic treatment with amyloid beta(1-42) inhibits non-cholinergic high-affinity choline transport in NG108-15 cells through protein kinase C signaling

    Czech Academy of Sciences Publication Activity Database

    Nováková, Jana; Mikasová, Lenka; Machová, Eva; Lisá, Věra; Doležal, Vladimír

    2005-01-01

    Roč. 1062, č. 1-2 (2005), s. 101-110 ISSN 0006-8993 R&D Projects: GA AV ČR(CZ) IAA5011206; GA MŠk(CZ) LC554 Grant - others:Lipidiet(XE) QLK1-CT-2002-00172 Institutional research plan: CEZ:AV0Z50110509 Keywords : choline transporter * beta-amyloid * protein kinase C Subject RIV: ED - Physiology Impact factor: 2.296, year: 2005

  4. Behavior of beta-Amyloid 1-16 at the Air-Water Interface at Varying pH by Nonlinear Spectroscopy and Molecular Dynamics Simulations

    Czech Academy of Sciences Publication Activity Database

    Miller, A. E.; Petersen, P. B.; Hollars, C. H.; Saykally, R. J.; Heyda, Jan; Jungwirth, Pavel

    2011-01-01

    Roč. 115, č. 23 (2011), s. 5873-5880 ISSN 1089-5639 R&D Projects: GA MŠk LC512; GA ČR GA203/08/0114 Grant - others:NSF(US) 0650950 Institutional research plan: CEZ:AV0Z40550506 Keywords : beta-amyloid * air /water interface * SHG spectroscopy * molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.946, year: 2011

  5. Neurodegenerative cerebrospinal fluid biomarkers tau and amyloid beta predict functional, quality of life, and neuropsychological outcomes after aneurysmal subarachnoid hemorrhage.

    Science.gov (United States)

    Joswig, Holger; Korte, Wolfgang; Früh, Severin; Epprecht, Lorenz; Hildebrandt, Gerhard; Fournier, Jean-Yves; Stienen, Martin Nikolaus

    2018-04-01

    Cerebrospinal fluid (CSF) biomarkers might be useful in predicting outcome after aneurysmal subarachnoid hemorrhage (aSAH). It was the aim to determine whether tau and amyloid beta CSF concentrations predict functional, health-related quality of life (hrQoL), and neuropsychological outcomes after aSAH. Ventricular CSF was obtained from n = 24 aSAH patients at admission (D0), day 2 (D2), and day 6 (D6). CSF total (t)Tau, phosphorylated (p)Tau (181P) , and amyloid beta (1-40 and 1-42) (Aβ40/Aβ42) levels were compared between patients with favorable and unfavorable functional (modified Rankin Scale (mRS)), hrQoL (Euro-Qol (EQ-5D)), and neuropsychological outcomes at 3 (3 m) and 12 months (12 m). Patients with unfavorable functional (mRS 4-6) and hrQoL outcome (EQ-5D z-score ≤ - 1.0) at 3 and 12 m had higher CSF tTau/pTau and lower Aβ40/Aβ42 at D0, D2, and D6 with varying degrees of statistical significance. In terms of predicting neuropsychological outcome, CSF pTau showed a statistically significant correlation with the z-scores of executive function (r = - 0.7486, p = 0.008), verbal memory (r = - 0.8101, p = 0.002), attention (r = - 0.6498, p = 0.030), and visuospatial functioning (r = - 0.6944, p = 0.017) at 3 m. At 12 m, CSF pTau had statistically significant correlations with the z-scores of verbal memory (r = - 0.7473, p = 0.008) and visuospatial functioning (r = - 0.6678, p = 0.024). In conclusion, higher tTau/pTau and lower Aβ40/Aβ42 CSF levels predict unfavorable long-term functional and hrQoL outcomes. Neuropsychological deficits correlate with increased CSF tTau and pTau concentrations.

  6. Amyloid beta Fibril Elongation by Monomers Involves Disorder at the Tip

    Czech Academy of Sciences Publication Activity Database

    Bacci, M.; Vymětal, Jiří; Mihajlovic, M.; Caflisch, A.; Vitalis, A.

    2017-01-01

    Roč. 13, č. 10 (2017), s. 5117-5130 ISSN 1549-9618 Institutional support: RVO:61388963 Keywords : molecular dynamics simulations * atomic resolution structure * A beta Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 5.245, year: 2016

  7. Human amyloid β peptide and tau co-expression impairs behavior and causes specific gene expression changes in Caenorhabditis elegans.

    Science.gov (United States)

    Wang, Chenyin; Saar, Valeria; Leung, Ka Lai; Chen, Liang; Wong, Garry

    2018-01-01

    Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the presence of extracellular amyloid plaques consisting of Amyloidpeptide (Aβ) aggregates and neurofibrillary tangles formed by aggregation of hyperphosphorylated microtubule-associated protein tau. We generated a novel invertebrate model of AD by crossing Aβ1-42 (strain CL2355) with either pro-aggregating tau (strain BR5270) or anti-aggregating tau (strain BR5271) pan-neuronal expressing transgenic Caenorhabditis elegans. The lifespan and progeny viability of the double transgenic strains were significantly decreased compared with wild type N2 (P5E-21). RNA interference of 13 available top up-regulated genes in Aβ1-42+pro-aggregating tau animals revealed that F-box family genes and nep-4 could enhance life span deficits and chemotaxis deficits while Y39G8C.2 (TTBK2) could suppress these behaviors. Comparing the list of regulated genes from C. elegans to the top 60 genes related to human AD confirmed an overlap of 8 genes: patched homolog 1, PTCH1 (ptc-3), the Rab GTPase activating protein, TBC1D16 (tbc-16), the WD repeat and FYVE domain-containing protein 3, WDFY3 (wdfy-3), ADP-ribosylation factor guanine nucleotide exchange factor 2, ARFGEF2 (agef-1), Early B-cell Factor, EBF1 (unc-3), d-amino-acid oxidase, DAO (daao-1), glutamate receptor, metabotropic 1, GRM1 (mgl-2), prolyl 4-hydroxylase subunit alpha 2, P4HA2 (dpy-18 and phy-2). Taken together, our C. elegans double transgenic model provides insight on the fundamental neurobiologic processes underlying human AD and recapitulates selected transcriptomic changes observed in human AD brains. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Imaging of alpha(v)beta(3) expression by a bifunctional chimeric RGD peptide not cross-reacting with alpha(v)beta(5).

    Science.gov (United States)

    Zannetti, Antonella; Del Vecchio, Silvana; Iommelli, Francesca; Del Gatto, Annarita; De Luca, Stefania; Zaccaro, Laura; Papaccioli, Angela; Sommella, Jvana; Panico, Mariarosaria; Speranza, Antonio; Grieco, Paolo; Novellino, Ettore; Saviano, Michele; Pedone, Carlo; Salvatore, Marco

    2009-08-15

    To test whether a novel bifunctional chimeric peptide comprising a cyclic Arg-Gly-Asp pentapeptide covalently bound to an echistatin domain can discriminate alpha(v)beta(3) from alpha(v)beta(5) integrin, thus allowing the in vivo selective visualization of alpha(v)beta(3) expression by single-photon and positron emission tomography (PET) imaging. The chimeric peptide was preliminarily tested for inhibition of alpha(v)beta(3)-dependent cell adhesion and competition of 125I-echistatin binding to membrane of stably transfected K562 cells expressing alpha(v)beta(3) (Kalpha(v)beta(3)) or alpha(v)beta(5) (Kalpha(v)beta(5)) integrin. The chimeric peptide was then conjugated with diethylenetriaminepentaacetic acid and labeled with 111In for single-photon imaging, whereas a one-step procedure was used for labeling the full-length peptide and a truncated derivative, lacking the last five C-terminal amino acids, with 18F for PET imaging. Nude mice bearing tumors from Kalpha(v)beta(3), Kalpha(v)beta(5), U87MG human glioblastoma, and A431 human epidermoid cells were subjected to single-photon and PET imaging. Adhesion and competitive binding assays showed that the novel chimeric peptide selectively binds to alpha(v)beta(3) integrin and does not cross-react with alpha(v)beta(5). In agreement with in vitro findings, single-photon and PET imaging studies showed that the radiolabeled chimeric peptide selectively localizes in tumor xenografts expressing alphavbeta3 and fails to accumulate in those expressing alpha(v)beta(5) integrin. When 18F-labeled truncated derivative was used for PET imaging, alphavbeta3- and alpha(v)beta(5)-expressing tumors were visualized, indicating that the five C-terminal amino acids are required to differentially bind the two integrins. Our findings indicate that the novel chimeric Arg-Gly-Asp peptide, having no cross-reaction with alphavbeta5 integrin, allows highly selective alphavbeta3 expression imaging and monitoring.

  9. Binding of peptides to HLA-DQ molecules: peptide binding properties of the disease-associated HLA-DQ(alpha 1*0501, beta 1*0201) molecule

    DEFF Research Database (Denmark)

    Johansen, B H; Buus, S; Vartdal, F

    1994-01-01

    Peptide binding to DQ molecules has not previously been described. Here we report a biochemical peptide-binding assay specific for the DQ2 [i.e. DQ(alpha 1*0501, beta 1*0201)] molecule. This molecule was chosen since it shows a strong association to diseases such as celiac disease and insulin...

  10. Dodecylphosphocholine Micelles Induce Amyloid Formation of the PrP(110-136 Peptide via an α-Helical Metastable Conformation.

    Directory of Open Access Journals (Sweden)

    Simon Sauvé

    Full Text Available A peptide encompassing the conserved hydrophobic region and the first β-strand of the prion protein (PrP(110-136 shown to interact with the surface of dodecylphosphocholine micelles adopts an α-helical conformation that is localized below the head-group layer. This surface-bound peptide has a half-life of one day, and readily initiates the formation of amyloid fibrils. The presence of the latter was confirmed using birefringence microscopy upon Congo red binding and thioflavin T-binding induced fluorescence. The observation of this metastable α-helical conformer provides a unique snapshot of the early steps of the inter-conversion pathway. These findings together with the body of evidence from the prion literature allowed us to propose a mechanism for the conversion of PrPC to amyloid material.

  11. Dual Targeting of Amyloid-beta Clearance and Neuroinflammation as a Novel Therapeutic Approach against Alzheimer's Disease

    Science.gov (United States)

    Batarseh, Yazan S.

    Amyloid-beta (Abeta) cascade hypothesis suggests that Alzheimer's disease (AD) is related to an imbalance between the production and clearance of Abeta peptide. Sporadic AD has been related to faulty clearance of Abeta. Accumulation of Abeta oligomers (Abetao) has been linked to several downstream toxic effects including neuroinflammation, synaptic loss, and cellular death. Abeta transport across the blood-brain barrier (BBB) is one of the primary pathways for reducing Abeta load in the brain, which work hand in hand with other parenchymal mechanisms to reduce Abeta levels including intra and extracellular degradation by a family of Abeta degrading enzymes. Established AD drugs, such as the cholinesterase inhibitor donepezil, have been reported to have several additional non-cholinergic effects that alter Abeta pathology; reduce Abeta load, anti-inflammatory response, and attenuate synaptic loss. However, their limited effect only lead to minor improvements in AD symptoms without improving the prognosis of the disease. The lack of effective medical treatment for AD led to several studies focusing on establishing new therapeutic approaches to reduce Abeta pathology. We aimed to identify and characterize natural products that are capable of enhancing the BBB clearance of Abeta in addition to reducing neuroinflammation. Our first project was to investigate the role of oleocanthal (one of the active ingredients in extra-virgin olive oil; EVOO) on attenuating Abeta toxic effects on neurons and astrocytes. We developed Abeta oligomers (Abetao) induced inflammatory environment by exposing neurons and astrocytes to accumulative doses of Abetao to investigate oleocanthal effect on modulating Abetao pathological changes in neurons and astrocytes. Our findings demonstrated oleocanthal prevented Abetao-induced synaptic proteins, SNAP-25 and PSD-95, down-regulation in neurons, attenuated Abetao-induced inflammation, and restored glutamine transporter (GLT1) and glucose

  12. beta-Scission of C-3 (beta-carbon) alkoxyl radicals on peptides and proteins

    DEFF Research Database (Denmark)

    Headlam, H A; Mortimer, A; Easton, C J

    2000-01-01

    Exposure of proteins to radicals in the presence of O(2) brings about multiple changes in the target molecules. These alterations include oxidation of side chains, fragmentation, cross-linking, changes in hydrophobicity and conformation, altered susceptibility to proteolytic enzymes, and formation...... of methanal (formaldehyde). This product has been quantified with a number of oxidized peptides and proteins, and can account for up to 64% of the initial attacking radicals with some Ala peptides. When quantified together with the hydroperoxide precursors, these species account for up to 80% of the initial...... radicals, confirming that this is a major process. Methanal causes cell toxicity and DNA damage and is an animal carcinogen and a genotoxic agent in human cells. Thus, the formation and subsequent reaction of alkoxyl radicals formed at the C-3 position on aliphatic amino acid side chains on peptides...

  13. Lipidated alpha-Peptide/beta-Peptoid Hybrids with Potent Antiinflammatory Activity

    DEFF Research Database (Denmark)

    Skovbakke, Sarah L.; Larsen, Camilla J.; Heegaard, Peter M. H.

    2015-01-01

    is dependent on the length and position of the lipid element(s). The resulting lead compound, Pam-(Lys-beta NSpe)(6)-NH2, blocks LPS-induced cytokine secretion with a potency comparable to that of polymyxin B. The mode of action of this HDP mimic appears not to involve direct LPS interaction since it......, in contrast to polymyxin B, displayed only minor activity in the Limulus amebocyte lysate assay. Flow cytometry data showed specific interaction of a fluorophore-labeled lipidated a-peptide/beta-peptoid hybrid with monocytes and granulocytes indicating a cellular target expressed by these leukocyte subsets....

  14. Glutamine acts as a neuroprotectant against DNA damage, beta-amyloid and H2O2-induced stress.

    Directory of Open Access Journals (Sweden)

    Jianmin Chen

    Full Text Available Glutamine is the most abundant free amino acid in the human blood stream and is 'conditionally essential' to cells. Its intracellular levels are regulated both by the uptake of extracellular glutamine via specific transport systems and by its intracellular synthesis by glutamine synthetase (GS. Adding to the regulatory complexity, when extracellular glutamine is reduced GS protein levels rise. Unfortunately, this excess GS can be maladaptive. GS overexpression is neurotoxic especially if the cells are in a low-glutamine medium. Similarly, in low glutamine, the levels of multiple stress response proteins are reduced rendering cells hypersensitive to H(2O(2, zinc salts and DNA damage. These altered responses may have particular relevance to neurodegenerative diseases of aging. GS activity and glutamine levels are lower in the Alzheimer's disease (AD brain, and a fraction of AD hippocampal neurons have dramatically increased GS levels compared with control subjects. We validated the importance of these observations by showing that raising glutamine levels in the medium protects cultured neuronal cells against the amyloid peptide, Aβ. Further, a 10-day course of dietary glutamine supplementation reduced inflammation-induced neuronal cell cycle activation, tau phosphorylation and ATM-activation in two different mouse models of familial AD while raising the levels of two synaptic proteins, VAMP2 and synaptophysin. Together, our observations suggest that healthy neuronal cells require both intracellular and extracellular glutamine, and that the neuroprotective effects of glutamine supplementation may prove beneficial in the treatment of AD.

  15. Lycopene Prevents Amyloid [Beta]-Induced Mitochondrial Oxidative Stress and Dysfunctions in Cultured Rat Cortical Neurons.

    Science.gov (United States)

    Qu, Mingyue; Jiang, Zheng; Liao, Yuanxiang; Song, Zhenyao; Nan, Xinzhong

    2016-06-01

    Brains affected by Alzheimer's disease (AD) show a large spectrum of mitochondrial alterations at both morphological and genetic level. The causal link between β-amyloid (Aβ) and mitochondrial dysfunction has been established in cellular models of AD. We observed previously that lycopene, a member of the carotenoid family of phytochemicals, could counteract neuronal apoptosis and cell damage induced by Aβ and other neurotoxic substances, and that this neuroprotective action somehow involved the mitochondria. The present study aims to investigate the effects of lycopene on mitochondria in cultured rat cortical neurons exposed to Aβ. It was found that lycopene attenuated Aβ-induced oxidative stress, as evidenced by the decreased intracellular reactive oxygen species generation and mitochondria-derived superoxide production. Additionally, lycopene ameliorated Aβ-induced mitochondrial morphological alteration, opening of the mitochondrial permeability transition pores and the consequent cytochrome c release. Lycopene also improved mitochondrial complex activities and restored ATP levels in Aβ-treated neuron. Furthermore, lycopene prevented mitochondrial DNA damages and improved the protein level of mitochondrial transcription factor A in mitochondria. Those results indicate that lycopene protects mitochondria against Aβ-induced damages, at least in part by inhibiting mitochondrial oxidative stress and improving mitochondrial function. These beneficial effects of lycopene may account for its protection against Aβ-induced neurotoxicity.

  16. Hypocretin and brain β-amyloid peptide interactions in cognitive disorders and narcolepsy

    Directory of Open Access Journals (Sweden)

    Yves A Dauvilliers

    2014-06-01

    Full Text Available Objective: To examine relationships between cerebrospinal fluid (CSF Alzheimer’ disease (AD biomarkers and hypocretin-1 levels in patients with cognitive abnormalities and hypocretin-deficient narcolepsy-cataplexy (NC, estimate diagnostic accuracy, and determine correlations with sleep disturbances. Background: Sleep disturbances are frequent in AD. Interactions between brain β-amyloid (Aβ aggregation and a wake-related neurotransmitter hypocretin have been reported in a mouse model of AD. Methods: Ninety-one cognitive patients (37 AD, 16 mild cognitive impairment – MCI that converts to AD, 38 other dementias and 15 elderly patients with NC were recruited. Patients were diagnosed blind to CSF results. CSF A42, total tau, ptau181, and hypocretin-1 were measured. Sleep disturbances were assessed with questionnaires in 32 cognitive patients. Results: Lower CSF Aβ42 but higher tau and P-tau levels were found in AD and MCI compared to other dementias. CSF hypocretin-1 levels were higher in patients with MCI due to AD compared to other dementias, with a similar tendency for patients with advanced AD. CSF hypocretin-1 was significantly and independently associated with AD/MCI due to AD, with an OR of 2.70 after full adjustment, exceeding that for Aβ42. Aβ42 correlated positively with hypocretin-1 levels in advanced stage AD. No association was found between sleep disturbances and CSF biomarkers. No patients with NC achieved pathological cutoffs for Aβ42, with respectively one and four patients with NC above tau and P-tau cutoffs and no correlations between hypocretin-1 and other biomarkers. Conclusions: Our results suggest a pathophysiological relationship between Aβ42 and hypocretin-1 in the AD process, with higher CSF hypocretin-1 levels in early disease stages. Further longitudinal studies are needed to validate these biomarker interactions and to determine the cause-effect relationship and the role of wake/sleep behavior in amyloid

  17. IMPY, a potential {beta}-amyloid imaging probe for detection of prion deposits in scrapie-infected mice

    Energy Technology Data Exchange (ETDEWEB)

    Song, P.-J. [INSERM, U619, F-37000 Tours (France); Universite Francois-Rabelais, F-37000 Tours (France); IFR135, F-37000 Tours (France); Bernard, Serge [IFR135, F-37000 Tours (France); INRA, UR1282, IASP, 37380 Nouzilly (France)], E-mail: bernard@tours.inra.fr; Sarradin, Pierre [INRA, UR1282, IASP, 37380 Nouzilly (France); Vergote, Jackie [INSERM, U619, F-37000 Tours (France); Universite Francois-Rabelais, F-37000 Tours (France); IFR135, F-37000 Tours (France); Barc, Celine [INRA, UR1282, IASP, 37380 Nouzilly (France); Chalon, Sylvie [INSERM, U619, F-37000 Tours (France); Universite Francois-Rabelais, F-37000 Tours (France); IFR135, F-37000 Tours (France); Kung, M.-P.; Kung, Hank F. [Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Guilloteau, Denis [INSERM, U619, F-37000 Tours (France); Universite Francois-Rabelais, F-37000 Tours (France); IFR135, F-37000 Tours (France)

    2008-02-15

    Introduction: A potential single-photon emission computed tomography imaging agent for labeling of A{beta} plaques of Alzheimer's disease, IMPY (2-(4'-dimethylaminophenyl)-6-iodo-imidazo[1,2-a]pyridine), would be effective in detection of prion amyloid deposits in transmissible spongiform encephalopathies (TSEs). Methods: In vitro autoradiographic studies were carried out with [{sup 125}I]IMPY on brain sections from scrapie-infected mice and age-matched controls. Competition study was performed to evaluate the prion deposit binding specificity with nonradioactive IMPY. Results: Binding of [{sup 125}I]IMPY was observed in infected brain sections, while on age-matched control brain sections, there was no or very low labeling. Prion deposit binding was confirmed by histoblots with prion protein-specific monoclonal antibody 2D6. In the presence of nonradioactive IMPY, the binding of [{sup 125}I]IMPY was significantly inhibited in all regions studied. Conclusions: These findings indicate that IMPY can detect the prion deposits in vitro in scrapie-infected mice. Labeled with {sup 123}I, this ligand may be useful to quantitate prion deposit burdens in TSEs by in vivo imaging.

  18. Icariin Prevents Amyloid Beta-Induced Apoptosis via the PI3K/Akt Pathway in PC-12 Cells

    Directory of Open Access Journals (Sweden)

    Dongdong Zhang

    2015-01-01

    Full Text Available Icariin is a prenylated flavonol glycoside derived from the Chinese herb Epimedium sagittatum that exerts a variety of pharmacological activities and shows promise in the treatment and prevention of Alzheimer’s disease. In this study, we investigated the neuroprotective effects of icariin against amyloid beta protein fragment 25–35 (Aβ25–35 induced neurotoxicity in cultured rat pheochromocytoma PC12 cells and explored potential underlying mechanisms. Our results showed that icariin dose-dependently increased cell viability and decreased Aβ25–35-induced apoptosis, as assessed by MTT assay and Annexin V/propidium iodide staining, respectively. Results of western blot analysis revealed that the selective phosphatidylinositol 3-kinase (PI3K inhibitor LY294002 suppressed icariin-induced Akt phosphorylation, suggesting that the protective effects of icariin are associated with activation of the PI3K/Akt signaling pathway. LY294002 also blocked the icariin-induced downregulation of proapoptotic factors Bax and caspase-3 and upregulation of antiapoptotic factor Bcl-2 in Aβ25–35-treated PC12 cells. These findings provide further evidence for the clinical efficacy of icariin in the treatment of Alzheimer’s disease.

  19. Beta-amyloid deposition in patients with major depressive disorder with differing levels of treatment resistance: a pilot study.

    Science.gov (United States)

    Li, Peng; Hsiao, Ing-Tsung; Liu, Chia-Yih; Chen, Chia-Hsiang; Huang, She-Yao; Yen, Tzu-Chen; Wu, Kuan-Yi; Lin, Kun-Ju

    2017-12-01

    Lack of treatment response in patients with late-life depression is common. The role of brain beta-amyloid (Aβ) deposition in treatment outcome in subjects with late-life depression remains unclear. The present study aimed to investigate brain Aβ deposition in patients with major depressive disorder (MDD) with differing treatment outcomes in vivo using 18 F-florbetapir imaging. This study included 62 MDD patients and 18 healthy control subjects (HCs).We first employed the Maudsley staging method (MSM) to categorize MDD patients into two groups according to treatment response: mild treatment resistance (n = 29) and moderate-to-severe treatment resistance (n = 33).The standard uptake value ratio (SUVR) of each volume of interest was analysed, and voxel-wise comparisons were made between the MDD patients and HCs. Vascular risk factors, serum homocysteine level, and apolipoprotein E (ApoE) genotype were also determined. The MDD patients with moderate-to-severe treatment resistance had higher 18 F-florbetapir SUVRs than the HCs in the parietal region (P depressive symptoms may represent prodromal manifestations of Alzheimer's disease (AD). Depressive symptomatology in old age, particularly in subjects with a poor treatment response, may underscore early changes of AD-related pathophysiology.

  20. Increased tau phosphorylation and beta amyloid in the hipocampus of mouse pups by early life lead exposure.

    Science.gov (United States)

    Li, N; Yu, Z L; Wang, L; Zheng, Y T; Jia, J X; Wang, Q; Zhu, M J; Liu, X L; Xia, X; Li, W J

    2010-06-01

    The aim of this study was to investigate the effects of maternal lead exposure on the learning and memory ability and expression of tau protein phosphorylation (P-tau) and beta amyloid protein (Abeta) in hippocampus of mice offspring. Pb exposure initiated from beginning of gestation to weaning. Pb acetate administered in drinking solutions was dissolved in distilled deionized water at the concentrations of 0.1%, 0.5% and 1% groups. On the 21 th of postnatal day, the learning and memory ability of the mouse pups was tested by Water Maze test and the Pb levels in blood and hippocampus of the offspring were also determined. The expression of P-tau and Abeta in hippocampus was measured by immunohistochemistry and Western blotting. The Pb levels in blood and hippocampus of all exposure groups were significantly higher than that of the control group ( P < 0.05). In Water Maze test, the performances of 0.5% and 1% groups were worse than that of the control group ( P < 0.05). The expression of P-tau and Abeta was increased in Pb exposed groups than that of the control group ( P < 0.05). Tau hyper-phosphorylation and Abeta increase in the hippocampus of pups may contribute to the impairment of learning and memory associated with maternal Pb exposure.

  1. Novel neuroprotective function of apical-basal polarity gene crumbs in amyloid beta 42 (aβ42 mediated neurodegeneration.

    Directory of Open Access Journals (Sweden)

    Andrew M Steffensmeier

    Full Text Available Alzheimer's disease (AD, OMIM: 104300, a progressive neurodegenerative disorder with no cure to date, is caused by the generation of amyloid-beta-42 (Aβ42 aggregates that trigger neuronal cell death by unknown mechanism(s. We have developed a transgenic Drosophila eye model where misexpression of human Aβ42 results in AD-like neuropathology in the neural retina. We have identified an apical-basal polarity gene crumbs (crb as a genetic modifier of Aβ42-mediated-neuropathology. Misexpression of Aβ42 caused upregulation of Crb expression, whereas downregulation of Crb either by RNAi or null allele approach rescued the Aβ42-mediated-neurodegeneration. Co-expression of full length Crb with Aβ42 increased severity of Aβ42-mediated-neurodegeneration, due to three fold induction of cell death in comparison to the wild type. Higher Crb levels affect axonal targeting from the retina to the brain. The structure function analysis identified intracellular domain of Crb to be required for Aβ42-mediated-neurodegeneration. We demonstrate a novel neuroprotective role of Crb in Aβ42-mediated-neurodegeneration.

  2. Structure of the antimicrobial beta-hairpin peptide protegrin-1 in a DLPC lipid bilayer investigated by molecular dynamics simulation

    DEFF Research Database (Denmark)

    Khandelia, Himanshu; Kaznessis, Yiannis N

    2007-01-01

    -550]), and to delineate specific peptide-membrane interactions which are responsible for the peptide's membrane binding properties. A novel, previously unknown, "kick" shaped conformation of the peptide was detected, where a bend at the C-terminal beta-strand of the peptide caused the peptide backbone at residues 16...... different initial orientations of the peptide converged to the same final equilibrium orientation of the peptide relative to the bilayer. The kick-shaped conformation was observed only in one of the two simulations....... of the peptide in a membrane environment (previously solved only in solution [R.L. Fahrner, T. Dieckmann, S.S.L. Harwig, R.I. Lehrer, D. Eisenberg, J. Feigon, Solution structure of protegrin-1, a broad-spectrum antimicrobial peptide from porcine leukocytes. Chemistry and Biology, 3 (1996) 543...

  3. 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.

  4. Amyloidpeptides 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

  5. Complex of amyloid beta peptides with 24-hydroxycholesterol and its effect on hemicholinium-3 sensitive carriers

    Czech Academy of Sciences Publication Activity Database

    Krištofíková, Z.; Kopecký, V. Jr.; Hofbauerová, Kateřina; Hovorková, P.; Řípová, D.

    2008-01-01

    Roč. 33, č. 3 (2008), s. 412-421 ISSN 0364-3190 Grant - others:GA Mšk(CZ) MZOPCP2005 Institutional research plan: CEZ:AV0Z50200510 Keywords : aging * hippocampus * choline carriers Subject RIV: EE - Microbiology, Virology Impact factor: 2.260, year: 2008

  6. Huperzine A protects isolated rat brain mitochondria against beta-amyloid peptide.

    Science.gov (United States)

    Gao, Xin; Zheng, Chun Yan; Yang, Ling; Tang, Xi Can; Zhang, Hai Yan

    2009-06-01

    Our previous work in cells and animals showed that mitochondria are involved in the neuroprotective effect of huperzine A (HupA). In this study, the effects of HupA on isolated rat brain mitochondria were investigated. In addition to inhibiting the Abeta(25-35) (40 microM)-induced decrease in mitochondrial respiration, adenosine 5'-triphosphate (ATP) synthesis, enzyme activity, and transmembrane potential, HupA (0.01 or 0.1 microM) effectively prevented Abeta-induced mitochondrial swelling, reactive oxygen species increase, and cytochrome c release. More interestingly, administration of HupA to isolated mitochondria promoted the rate of ATP production and blocked mitochondrial swelling caused by normal osmosis. These results indicate that HupA protects mitochondria against Abeta at least in part by preserving membrane integrity and improving energy metabolism. These direct effects on mitochondria further extend the noncholinergic functions of HupA.

  7. 18F-Florbetaben PET beta-amyloid binding expressed in Centiloids

    International Nuclear Information System (INIS)

    Rowe, Christopher C.; Dore, Vincent; Jones, Gareth; Baxendale, David; Mulligan, Rachel S.; Bullich, Santiago; Stephens, Andrew W.; Dinkelborg, Ludger; De Santi, Susan; Masters, Colin L.; Villemagne, Victor L.

    2017-01-01

    The Centiloid (CL) method enables quantitative values from Aβ-amyloid (Aβ) imaging to be expressed in a universal unit providing pathological, diagnostic and prognostic thresholds in clinical practice and research and allowing integration of multiple tracers and methods. The method was developed for 11 C-PiB scans with zero CL set as the average in young normal subjects and 100 CL the average in subjects with mild Alzheimer's disease (AD). The method allows derivation of equations to convert the uptake value of any tracer into the same standard CL units but first requires head-to-head comparison with 11 C-PiB results. We derived the equation to express 18 F-florbetaben (FBB) binding in CL units. Paired PiB and FBB PET scans were obtained in 35 subjects. including ten young normal subjects aged under 45 years (33 ± 8 years). FBB images were acquired from 90 to 110 min after injection. Spatially normalized images were analysed using the standard CL method (SPM8 coregistration of PET data to MRI data and the MNI-152 atlas) and standard CL regions (cortex and whole cerebellum downloaded from http://www.gaain.org). FBB binding was strongly correlated with PiB binding (R 2 = 0.96, SUVR FBB = 0.61 x SUVR PiB + 0.39). The equation to derive CL values from FBB SUVR was CL units = 153.4 x SUVR FBB - 154.9. The CL value in the young normal subjects was -1.08 ± 6.81 for FBB scans compared to -0.32 ± 3.48 for PiB scans, giving a variance ratio of 1.96 (SD FBB CL /SD PiB CL ). 18 F-FBB binding is strongly correlated with PiB binding and FBB results can now be expressed in CL units. (orig.)

  8. A ketogenic diet reduces amyloid beta 40 and 42 in a mouse model of Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Van Leuven Fred

    2005-10-01

    Full Text Available Abstract Background Alzheimer's disease (AD is a progressive neurodegenerative disorder that primarily strikes the elderly. Studies in both humans and animal models have linked the consumption of cholesterol and saturated fats with amyloid-β (Aβ deposition and development of AD. Yet, these studies did not examine high fat diets in combination with reduced carbohydrate intake. Here we tested the effect of a high saturated fat/low carbohydrate diet on a transgenic mouse model of AD. Results Starting at three months of age, two groups of female transgenic mice carrying the "London" APP mutation (APP/V717I were fed either, a standard diet (SD composed of high carbohydrate/low fat chow, or a ketogenic diet (KD composed of very low carbohydrate/high saturated fat chow for 43 days. Animals fed the KD exhibited greatly elevated serum ketone body levels, as measured by β-hydroxybutyrate (3.85 ± 2.6 mM, compared to SD fed animals (0.29 ± 0.06 mM. In addition, animals fed the KD lost body weight (SD 22.2 ± 0.6 g vs. KD 17.5 ± 1.4 g, p = 0.0067. In contrast to earlier studies, the brief KD feeding regime significantly reduced total brain Aβ levels by approximately 25%. Despite changes in ketone levels, body weight, and Aβ levels, the KD diet did not alter behavioral measures. Conclusion Previous studies have suggested that diets rich in cholesterol and saturated fats increased the deposition of Aβ and the risk of developing AD. Here we demonstrate that a diet rich in saturated fats and low in carbohydrates can actually reduce levels of Aβ. Therefore, dietary strategies aimed at reducing Aβ levels should take into account interactions of dietary components and the metabolic outcomes, in particular, levels of carbohydrates, total calories, and presence of ketone bodies should be considered.

  9. Intrinsic excitability changes induced by acute treatment of hippocampal CA1 pyramidal neurons with exogenous amyloid β peptide

    Science.gov (United States)

    Scullion, Sarah; Brown, Jon T.; Randall, Andrew D.

    2015-01-01

    ABSTRACT Accumulation of beta‐amyloid (Aβ) peptides in the human brain is a canonical pathological hallmark of Alzheimer's disease (AD). Recent work in Aβ‐overexpressing transgenic mice indicates that increased brain Aβ levels can be associated with aberrant epileptiform activity. In line with this, such mice can also exhibit altered intrinsic excitability (IE) of cortical and hippocampal neurons: these observations may relate to the increased prevalence of seizures in AD patients. In this study, we examined what changes in IE are produced in hippocampal CA1 pyramidal cells after 2–5 h treatment with an oligomeric preparation of synthetic human Aβ 1–42 peptide. Whole cell current clamp recordings were compared between Aβ‐(500 nM) and vehicle‐(DMSO 0.05%) treated hippocampal slices obtained from mice. The soluble Aβ treatment did not produce alterations in sub‐threshold intrinsic properties, including membrane potential, input resistance, and hyperpolarization activated “sag”. Similarly, no changes were noted in the firing profile evoked by 500 ms square current supra‐threshold stimuli. However, Aβ 500 nM treatment resulted in the hyperpolarization of the action potential (AP) threshold. In addition, treatment with Aβ at 500 nM depressed the after‐hyperpolarization that followed both a single AP or 50 Hz trains of a number of APs between 5 and 25. These data suggest that acute exposure to soluble Aβ oligomers affects IE properties of CA1 pyramidal neurons differently from outcomes seen in transgenic models of amyloidopathy. However, in both chronic and acute models, the IE changes are toward hyperexcitability, reinforcing the idea that amyloidopathy and increased incidence in seizures might be causally related in AD patients. © 2014 The Authors Hippocampus Published by Wiley Periodicals, Inc. PMID:25515596

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

    Directory of Open Access Journals (Sweden)

    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.

  11. Chronic apocynin treatment attenuates beta amyloid plaque size and microglial number in hAPP(751(SL mice.

    Directory of Open Access Journals (Sweden)

    Melinda E Lull

    Full Text Available NADPH oxidase is implicated in neurotoxic microglial activation and the progressive nature of Alzheimer's Disease (AD. Here, we test the ability of two NADPH oxidase inhibitors, apocynin and dextromethorphan (DM, to reduce learning deficits and neuropathology in transgenic mice overexpressing human amyloid precursor protein with the Swedish and London mutations (hAPP(751(SL.Four month old hAPP(751(SL mice were treated daily with saline, 15 mg/kg DM, 7.5 mg/kg DM, or 10 mg/kg apocynin by gavage for four months.Only hAPP(751(SL mice treated with apocynin showed reduced plaque size and a reduction in the number of cortical microglia, when compared to the saline treated group. Analysis of whole brain homogenates from all treatments tested (saline, DM, and apocynin demonstrated low levels of TNFα, protein nitration, lipid peroxidation, and NADPH oxidase activation, indicating a low level of neuroinflammation and oxidative stress in hAPP(751(SL mice at 8 months of age that was not significantly affected by any drug treatment. Despite in vitro analyses demonstrating that apocynin and DM ameliorate Aβ-induced extracellular superoxide production and neurotoxicity, both DM and apocynin failed to significantly affect learning and memory tasks or synaptic density in hAPP(751(SL mice. To discern how apocynin was affecting plaque levels (plaque load and microglial number in vivo, in vitro analysis of microglia was performed, revealing no apocynin effects on beta-amyloid (Aβ phagocytosis, microglial proliferation, or microglial survival.Together, this study suggests that while hAPP(751(SL mice show increases in microglial number and plaque load, they fail to exhibit elevated markers of neuroinflammation consistent with AD at 8 months of age, which may be a limitation of this animal model. Despite absence of clear neuroinflammation, apocynin was still able to reduce both plaque size and microglial number, suggesting that apocynin may have additional

  12. Using Multifunctional Peptide Conjugated Au Nanorods for Monitoring β-amyloid Aggregation and Chemo-Photothermal Treatment of Alzheimer's Disease.

    Science.gov (United States)

    Li, Meng; Guan, Yijia; Zhao, Andong; Ren, Jinsong; Qu, Xiaogang

    2017-01-01

    Development of sensitive detectors of Aβ aggregates and effective inhibitors of Aβ aggregation are of diagnostic importance and therapeutic implications for Alzheimer's disease (AD) treatment. Herein, a novel strategy has been presented by self-assembly of peptide conjugated Au nanorods (AuP) as multifunctional Aβ fibrillization detectors and inhibitors. Our design combines the unique high NIR absorption property of AuNRs with two known Aβ inhibitors, Aβ15-20 and polyoxometalates (POMs). The synthesized AuP can effectively inhibit Aβ aggregation and dissociate amyloid deposits with NIR irradiation both in buffer and in mice cerebrospinal fluid (CSF), and protect cells from Aβ-related toxicity upon NIR irradiation. In addition, with the shape and size-dependent optical properties, the nanorods can also act as effective diagnostic probes to sensitively detect the Aβ aggregates. This is the first report to integrate 3 segments, an Aβ-targeting element, a reporter and inhibitors, in one drug delivery system for AD treatment.

  13. Posttranslational nitro-glycative modifications of albumin in Alzheimer's disease: implications in cytotoxicity and amyloidpeptide aggregation.

    Science.gov (United States)

    Ramos-Fernández, Eva; Tajes, Marta; Palomer, Ernest; Ill-Raga, Gerard; Bosch-Morató, Mònica; Guivernau, Biuse; Román-Dégano, Irene; Eraso-Pichot, Abel; Alcolea, Daniel; Fortea, Juan; Nuñez, Laura; Paez, Antonio; Alameda, Francesc; Fernández-Busquets, Xavier; Lleó, Alberto; Elosúa, Roberto; Boada, Mercé; Valverde, Miguel A; Muñoz, Francisco J

    2014-01-01

    Glycation and nitrotyrosination are pathological posttranslational modifications that make proteins prone to losing their physiological properties. Since both modifications are increased in Alzheimer's disease (AD) due to amyloidpeptide (Aβ) accumulation, we have studied their effect on albumin, the most abundant protein in cerebrospinal fluid and blood. Brain and plasmatic levels of glycated and nitrated albumin were significantly higher in AD patients than in controls. In vitro turbidometry and electron microscopy analyses demonstrated that glycation and nitrotyrosination promote changes in albumin structure and biochemical properties. Glycated albumin was more resistant to proteolysis and less uptake by hepatoma cells occurred. Glycated albumin also reduced the osmolarity expected for a solution containing native albumin. Both glycation and nitrotyrosination turned albumin cytotoxic in a cell type-dependent manner for cerebral and vascular cells. Finally, of particular relevance to AD, these modified albumins were significantly less effective in avoiding Aβ aggregation than native albumin. In summary, nitrotyrosination and especially glycation alter albumin structural and biochemical properties, and these modifications might contribute for the progression of AD.

  14. Sildenafil protects neuronal cells from mitochondrial toxicity induced by β-amyloid peptide via ATP-sensitive K+ channels.

    Science.gov (United States)

    Son, Yonghae; Kim, Koanhoi; Cho, Hyok-Rae

    2018-06-02

    To understand the molecular mechanisms underlying the beneficial effects of sildenafil in animal models of neurological disorders, we investigated the effects of sildenafil on the mitochondrial toxicity induced by β-amyloid (Aβ) peptide. Treatment of HT-22 hippocampal neuronal cells with Aβ 25∼35 results in increased mitochondrial Ca 2+ load, which is subsequently suppressed by sildenafil as well as by diazoxide, a selective opener of the ATP-sensitive K + channels (K ATP ). However, the suppressive effects of sildenafil and diazoxide are significantly attenuated by 5-hydroxydecanoic acid (5-HD), a K ATP inhibitor. The increased mitochondrial Ca 2+ overload is accompanied by decrease in the intracellular ATP concentration, increase in intracellular ROS generation, occurrence of mitochondrial permeability transition, and activation of caspase-9 and cell death. Exposure to sildenafil inhibited the mitochondria-associated changes and cell death induced by Aβ. However, the inhibitory effects of sildenafil are abolished or weakened in the presence of 5-HD, suggesting that opening of the mitochondrial K ATP is required for sildenafil to exert these effects. Taken together, these results indicate that at the mitochondrial levels, sildenafil plays a protective role towards neuronal cell in an environment rich in Aβ, and exerts its effects via the mitochondrial K ATP channels-dependent mechanisms. Copyright © 2018 Elsevier Inc. All rights reserved.

  15. Amyloidpeptide-specific DARPins as a novel class of potential therapeutics for Alzheimer disease.

    Science.gov (United States)

    Hanenberg, Michael; McAfoose, Jordan; Kulic, Luka; Welt, Tobias; Wirth, Fabian; Parizek, Petra; Strobel, Lisa; Cattepoel, Susann; Späni, Claudia; Derungs, Rebecca; Maier, Marcel; Plückthun, Andreas; Nitsch, Roger M

    2014-09-26

    Passive immunization with anti-amyloidpeptide (Aβ) antibodies is effective in animal models of Alzheimer disease. With the advent of efficient in vitro selection technologies, the novel class of designed ankyrin repeat proteins (DARPins) presents an attractive alternative to the immunoglobulin scaffold. DARPins are small and highly stable proteins with a compact modular architecture ideal for high affinity protein-protein interactions. In this report, we describe the selection, binding profile, and epitope analysis of Aβ-specific DARPins. We further showed their ability to delay Aβ aggregation and prevent Aβ-mediated neurotoxicity in vitro. To demonstrate their therapeutic potential in vivo, mono- and trivalent Aβ-specific DARPins (D23 and 3×D23) were infused intracerebroventricularly into the brains of 11-month-old Tg2576 mice over 4 weeks. Both D23 and 3×D23 treatments were shown to result in improved cognitive performance and reduced soluble Aβ levels. These findings demonstrate the therapeutic potential of Aβ-specific DARPins for the treatment of Alzheimer disease. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Low background and high contrast PET imaging of amyloid-{beta} with [{sup 11}C]AZD2995 and [{sup 11}C]AZD2184 in Alzheimer's disease patients

    Energy Technology Data Exchange (ETDEWEB)

    Forsberg, Anton; Andersson, Jan; Varnaes, Katarina; Halldin, Christer [Karolinska Institutet, Centre for Psychiatry Research, Department of Clinical Neuroscience, Stockholm (Sweden); Jureus, Anders; Swahn, Britt-Marie; Sandell, Johan; Julin, Per; Svensson, Samuel [AstraZeneca Research and Development, Neuroscience Research and Therapy Area, Soedertaelje (Sweden); Cselenyi, Zsolt; Schou, Magnus; Johnstroem, Peter; Farde, Lars [Karolinska Institutet, Centre for Psychiatry Research, Department of Clinical Neuroscience, Stockholm (Sweden); Karolinska Hospital, AstraZeneca Translational Sciences Centre, PET CoE, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm (Sweden); Eriksdotter, Maria; Freund-Levi, Yvonne [Karolinska Institutet, Clinical Geriatrics, Department of Neurobiology, Care Sciences and Society, Stockholm (Sweden); Karolinska University Hospital, Department of Geriatric Medicine, Stockholm (Sweden); Jeppsson, Fredrik [AstraZeneca Research and Development, Neuroscience Research and Therapy Area, Soedertaelje (Sweden); Karolinska Institutet, Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Stockholm (Sweden)

    2013-04-15

    The aim of this study was to evaluate AZD2995 side by side with AZD2184 as novel PET radioligands for imaging of amyloid-{beta} in Alzheimer's disease (AD). In vitro binding of tritium-labelled AZD2995 and AZD2184 was studied and compared with that of the established amyloid-{beta} PET radioligand PIB. Subsequently, a first-in-human in vivo PET study was performed using [{sup 11}C]AZD2995 and [{sup 11}C]AZD2184 in three healthy control subjects and seven AD patients. AZD2995, AZD2184 and PIB were found to share the same binding site to amyloid-{beta}. [{sup 3}H]AZD2995 had the highest signal-to-background ratio in brain tissue from patients with AD as well as in transgenic mice. However, [{sup 11}C]AZD2184 had superior imaging properties in PET, as shown by larger effect sizes comparing binding potential values in cortical regions of AD patients and healthy controls. Nevertheless, probably due to a lower amount of nonspecific binding, the group separation of the distribution volume ratio values of [{sup 11}C]AZD2995 was greater in areas with lower amyloid-{beta} load, e.g. the hippocampus. Both AZD2995 and AZD2184 detect amyloid-{beta} with high affinity and specificity and also display a lower degree of nonspecific binding than that reported for PIB. Overall [{sup 11}C]AZD2184 seems to be an amyloid-{beta} radioligand with higher uptake and better group separation when compared to [{sup 11}C]AZD2995. However, the very low nonspecific binding of [{sup 11}C]AZD2995 makes this radioligand potentially interesting as a tool to study minute levels of amyloid-{beta}. This sensitivity may be important in investigating, for example, early prodromal stages of AD or in the longitudinal study of a disease modifying therapy. (orig.)

  17. {sup 18}F-Florbetaben PET beta-amyloid binding expressed in Centiloids

    Energy Technology Data Exchange (ETDEWEB)

    Rowe, Christopher C. [Austin Health, Department of Molecular Imaging and Therapy, Centre for PET, Melbourne, VIC (Australia); University of Melbourne, Department of Medicine, Melbourne (Australia); Dore, Vincent [Austin Health, Department of Molecular Imaging and Therapy, Centre for PET, Melbourne, VIC (Australia); eHealth, CSIRO Health and Biosecurity, Brisbane, QLD (Australia); Jones, Gareth; Baxendale, David; Mulligan, Rachel S. [Austin Health, Department of Molecular Imaging and Therapy, Centre for PET, Melbourne, VIC (Australia); Bullich, Santiago; Stephens, Andrew W.; Dinkelborg, Ludger [Piramal Imaging GmbH, Berlin (Germany); De Santi, Susan [Piramal Pharma, Inc, Boston, MA (United States); Masters, Colin L. [The Florey Institute of Neuroscience and Mental Health, Melbourne, VIC (Australia); Villemagne, Victor L. [Austin Health, Department of Molecular Imaging and Therapy, Centre for PET, Melbourne, VIC (Australia); University of Melbourne, Department of Medicine, Melbourne (Australia); The Florey Institute of Neuroscience and Mental Health, Melbourne, VIC (Australia)

    2017-11-15

    The Centiloid (CL) method enables quantitative values from Aβ-amyloid (Aβ) imaging to be expressed in a universal unit providing pathological, diagnostic and prognostic thresholds in clinical practice and research and allowing integration of multiple tracers and methods. The method was developed for {sup 11}C-PiB scans with zero CL set as the average in young normal subjects and 100 CL the average in subjects with mild Alzheimer's disease (AD). The method allows derivation of equations to convert the uptake value of any tracer into the same standard CL units but first requires head-to-head comparison with {sup 11}C-PiB results. We derived the equation to express {sup 18}F-florbetaben (FBB) binding in CL units. Paired PiB and FBB PET scans were obtained in 35 subjects. including ten young normal subjects aged under 45 years (33 ± 8 years). FBB images were acquired from 90 to 110 min after injection. Spatially normalized images were analysed using the standard CL method (SPM8 coregistration of PET data to MRI data and the MNI-152 atlas) and standard CL regions (cortex and whole cerebellum downloaded from http://www.gaain.org). FBB binding was strongly correlated with PiB binding (R{sup 2} = 0.96, SUVR{sub FBB} = 0.61 x SUVR{sub PiB} + 0.39). The equation to derive CL values from FBB SUVR was CL units = 153.4 x SUVR{sub FBB} - 154.9. The CL value in the young normal subjects was -1.08 ± 6.81 for FBB scans compared to -0.32 ± 3.48 for PiB scans, giving a variance ratio of 1.96 (SD{sub FBB} {sub CL}/SD{sub PiB} {sub CL}). {sup 18}F-FBB binding is strongly correlated with PiB binding and FBB results can now be expressed in CL units. (orig.)

  18. Coconut oil protects cortical neurons from amyloid beta toxicity by enhancing signaling of cell survival pathways.

    Science.gov (United States)

    Nafar, F; Clarke, J P; Mearow, K M

    2017-05-01

    Alzheimer's disease is a progressive neurodegenerative disease that has links with other conditions that can often be modified by dietary and life-style interventions. In particular, coconut oil has received attention as having potentially having benefits in lessening the cognitive deficits associated with Alzheimer's disease. In a recent report, we showed that neuron survival in cultures co-treated with coconut oil and Aβ was rescued compared to cultures exposed only to Aβ. Here we investigated treatment with Aβ for 1, 6 or 24 h followed by addition of coconut oil for a further 24 h, or treatment with coconut oil for 24 h followed by Aβ exposure for various periods. Neuronal survival and several cellular parameters (cleaved caspase 3, synaptophysin labeling and ROS) were assessed. In addition, the influence of these treatments on relevant signaling pathways was investigated with Western blotting. In terms of the treatment timing, our data indicated that coconut oil rescues cells pre-exposed to Aβ for 1 or 6 h, but is less effective when the pre-exposure has been 24 h. However, pretreatment with coconut oil prior to Aβ exposure showed the best outcomes. Treatment with octanoic or lauric acid also provided protection against Aβ, but was not as effective as the complete oil. The coconut oil treatment reduced the number of cells with cleaved caspase and ROS labeling, as well as rescuing the loss of synaptophysin labeling observed with Aβ treatment. Treatment with coconut oil, as well as octanoic, decanoic and lauric acids, resulted in a modest increase in ketone bodies compared to controls. The biochemical data suggest that Akt and ERK activation may contribute to the survival promoting influence of coconut oil. This was supported by observations that a PI3-Kinase inhibitor blocked the rescue effect of CoOil on Aβ amyloid toxicity. Further studies into the mechanisms of action of coconut oil and its constituent medium chain fatty acids are warranted

  19. Effect of four medicinal plants on Amyloid-β induced neurotoxicity in ...

    African Journals Online (AJOL)

    Amyloid-beta peptide (Aâ) is implicated in the pathogenesis of Alzheimer's disease (AD), a neurodegenerative disorder. This study was designed to determine the effect of four medicinal plants used to treat neurodegenerative diseases on Aâ-induced cell death. Cytotoxicity of the ethanol extracts of the plants was ...

  20. Characterization of the conformational space of a triple-stranded beta-sheet forming peptide with molecular dynamics simulations

    NARCIS (Netherlands)

    Soto, P; Colombo, G

    2004-01-01

    Molecular dynamics (MD) simulations have been performed on a series of mutants of the 20 amino acid peptide Betanova in order to critically assess the ability of MD simulations to reproduce the folding and stability of small beta-sheet-forming peptides on currently accessible timescales. Simulations

  1. Melting of a beta-Hairpin Peptide Using Isotope-Edited 2D IR Spectroscopy and Simulations

    NARCIS (Netherlands)

    Smith, Adam W.; Lessing, Joshua; Ganim, Ziad; Peng, Chunte Sam; Tokmakoff, Andrei; Roy, Santanu; Jansen, Thomas L. C.; Knoester, Jasper

    2010-01-01

    Isotope-edited two-dimensional infrared spectroscopy has been used! to characterize the conformational heterogeneity of the beta-hairpin peptide TrpZip2 (17.2) across its thermal unfolding transition Four isotopologues were synthesized to probe hydrogen bonding and solvent exposure of the beta-turn

  2. Melting of a beta-hairpin peptide using isotope-edited 2D IR spectroscopy and simulations.

    NARCIS (Netherlands)

    Smith, A.W.; Lessing, J.; Ganim, Z.; Peng, C.S.; Tokmakoff, A.; Roy, S.; Jansen, T.L.Th.A.; Knoester, J.

    2010-01-01

    Isotope-edited two-dimensional infrared spectroscopy has been used to characterize the conformational heterogeneity of the beta-hairpin peptide TrpZip2 (TZ2) across its thermal unfolding transition. Four isotopologues were synthesized to probe hydrogen bonding and solvent exposure of the beta-turn

  3. Targeted correction of a thalassemia-associated beta-globin mutation induced by pseudo-complementary peptide nucleic acids

    DEFF Research Database (Denmark)

    Lonkar, Pallavi; Kim, Ki-Hyun; Kuan, Jean Y

    2009-01-01

    Beta-thalassemia is a genetic disorder caused by mutations in the beta-globin gene. Triplex-forming oligonucleotides and triplex-forming peptide nucleic acids (PNAs) have been shown to stimulate recombination in mammalian cells via site-specific binding and creation of altered helical structures...

  4. Tumor targeting with radiolabeled alpha(v)beta(3) integrin binding peptides in a nude mouse model.

    NARCIS (Netherlands)

    Janssen, M.L.H.; Oyen, W.J.G.; Dijkgraaf, I.; Massuger, L.F.A.G.; Frielink, C.; Edwards, D.S.; Rajopadhye, M.; Boonstra, H.; Corstens, F.H.M.; Boerman, O.C.

    2002-01-01

    The alpha(v)beta(3) integrin is expressed on proliferating endothelial cells such as those present in growing tumors, as well as on tumor cells of various origin. Tumor-induced angiogenesis can be blocked in vivo by antagonizing the alpha(v)beta(3) integrin with small peptides containing the

  5. Serum β-amyloid peptide levels spike in the early stage of Alzheimer-like plaque pathology in an APP/PS1 double transgenic mouse model.

    Science.gov (United States)

    He, Jue; Qiao, Jin-Ping; Zhu, Shenghua; Xue, Mengzhou; Chen, Wenwu; Wang, Xinchun; Tempier, Adrien; Huang, Qingjun; Kong, Jiming; Li, Xin-Min

    2013-11-01

    Serum levels of β-amyloid (Aβ) peptides may represent an early biomarker in the diagnosis of Alzheimer's disease (AD). In the present study, we investigated the temporal kinetic changes in the levels of serum Aβ 1-42 and 40 in an amyloid precursor protein (APP)/presenilin (PS)1 double transgenic mouse model of AD. Serum Aβ peptide levels in 2-, 3-, 6-, 9- and 18-month old, and liver Aβ 1-40 level in 6-month old mice were measured using enzyme-linked immunosorbent assay (ELISA) kits. Results revealed that serum Aβ levels peaked in 3-month old transgenic mice, and the Aβ level in non-transgenic and transgenic mice is comparable in liver. Compared to the 6-month old transgenic mice, Congo red staining showed that the 3-month old transgenic mice had minimum brain Aβ plaques, corresponding to the early stage of Alzheimer-like plaque pathology, and confocal microscope images showed that the deposition of Aβ in their cerebral vessels was minimal. Furthermore, results of the water maze test, showed that memory was normal for the 3- month old transgenic mice when compared to age-matched non-transgenic mice. These results suggest that serum Aβ peptide levels may be peaked during the early stage of AD. Monitoring serum Aβ peptide levels in the potential AD population may provide an early diagnosis of AD prior to the appearance of clinical symptoms.

  6. The metabolic enhancer piracetam ameliorates the impairment of mitochondrial function and neurite outgrowth induced by ß-amyloid peptide

    Science.gov (United States)

    Kurz, C; Ungerer, I; Lipka, U; Kirr, S; Schütt, T; Eckert, A; Leuner, K; Müller, WE

    2010-01-01

    Background and purpose: β-Amyloid peptide (Aβ) is implicated in the pathogenesis of Alzheimer's disease by initiating a cascade of events from mitochondrial dysfunction to neuronal death. The metabolic enhancer piracetam has been shown to improve mitochondrial dysfunction following brain aging and experimentally induced oxidative stress. Experimental approach: We used cell lines (PC12 and HEK cells) and murine dissociated brain cells. The protective effects of piracetam in vitro and ex vivo on Aβ-induced impairment of mitochondrial function (as mitochondrial membrane potential and ATP production), on secretion of soluble Aβ and on neurite outgrowth in PC12 cells were investigated. Key results: Piracetam improves mitochondrial function of PC12 cells and acutely dissociated brain cells from young NMRI mice following exposure to extracellular Aβ1-42. Similar protective effects against Aβ1-42 were observed in dissociated brain cells from aged NMRI mice, or mice transgenic for mutant human amyloid precursor protein (APP) treated with piracetam for 14 days. Soluble Aβ load was markedly diminished in the brain of those animals after treatment with piracetam. Aβ production by HEK cells stably transfected with mutant human APP was elevated by oxidative stress and this was reduced by piracetam. Impairment of neuritogenesis is an important consequence of Aβ-induced mitochondrial dysfunction and Aβ-induced reduction of neurite growth in PC12 cells was substantially improved by piracetam. Conclusion and implications: Our findings strongly support the concept of improving mitochondrial function as an approach to ameliorate the detrimental effects of Aβ on brain function. This article is commented on by Moncada, pp. 217–219 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2010.00706.x and to view related papers by Pravdic et al. and Puerta et al. visit http://dx.doi.org/10.1111/j.1476-5381.2010.00698.x and http://dx.doi.org/10.1111/j

  7. Hubungan Konsumsi Antioksidan dari Makanan dengan Beta-Amyloid Plasma sebagai Penanda Gangguan Fungsi Kognitif pada Lanjut Usia

    Directory of Open Access Journals (Sweden)

    Ratna D Siregar

    2015-01-01

    Full Text Available AbstrakPenelitian ini bertujuan untuk mengetahui hubungan antara konsumsi vitamin A, vitamin C, vitamin E, zink dan selenium dari makanan dengan fungsi kognitif pada lanjut usia. Metoda penelitian adalah cross sectional study terhadap 145 lansia umur ≥ 60 tahun, pada dua kecamatan di Kabupaten Lima Puluh Kota Sumatra Barat. Wawancara konsumsi antioksidan menggunakan Food Frequency Questionnaires (FFQ, fungsi kognitif diperiksa dengan Montreal Cognitive Assesment versi Indonesia (MoCA-Ina, Aβ40 dan Aβ42 plasma diperiksa dengan metode ELISA. Data dianalisis menggunakan uji Mann-Whitney dan Chi-square. Pada hasil penelitian ditemukan 83 orang (57,2% lansia yang mengalami gangguan fungsi kognitif. Terdapat hubungan yang signifikan antara konsumsi vitamin C (p<0,049 dan vitamin E (p<0,037 tetapi tidak terdapat hubungan signifikan antara vitamin A, zink dan selenium dengan fungsi kognitif. Tidak terdapat hubungan yang signifikan antara konsumsi antioksidan dengan tingkat Aβ40 dan Aβ42 serta antara tingkat Aβ40 dan Aβ42 dengan fungsi kognitif masing-masing (p<0,058 dan p<0,350. Kesimpulan hasil penelitian ini didapatkan hubungan antara konsumsi vitamin C dan vitamin E dari makanan dengan fungsi kognitif. Tetapi tidak terdapat hubungan antara konsumsi antioksidan dengan Aβ40 dan Aβ42 plasma dan Aβ40 dan Aβ42 dengan fungsi kognitif.Kata kunci: antioksidan, beta-amyloid, fungsi kognitif, lanjut usiaAbstractThe objective of this study was to determine the relationship between consumption of vitamin A, vitamin C, vitamin E, zinc and selenium from foods with cognitive function in elderly. This was a cross-sectional study that was conducted to 145 elderly with age ≥ 60 years, in two districts in West Sumatra, in Lima Puluh Kota city. Interview antioxidant intake using a Food Frequency Questionnaires (FFQ, cognitive function was checked by Montreal Cognitive Assessment Indonesian version (MoCA-Ina, plasma Aβ40 dan Aβ42 were examined by ELISA

  8. Synaptotoxicity of Alzheimer beta amyloid can be explained by its membrane perforating property.

    Directory of Open Access Journals (Sweden)

    Fernando J Sepulveda

    Full Text Available The mechanisms that induce Alzheimer's disease (AD are largely unknown thereby deterring the development of disease-modifying therapies. One working hypothesis of AD is that Abeta excess disrupts membranes causing pore formation leading to alterations in ionic homeostasis. However, it is largely unknown if this also occurs in native brain neuronal membranes. Here we show that similar to other pore forming toxins, Abeta induces perforation of neuronal membranes causing an increase in membrane conductance, intracellular calcium and ethidium bromide influx. These data reveal that the target of Abeta is not another membrane protein, but that Abeta itself is the cellular target thereby explaining the failure of current therapies to interfere with the course of AD. We propose that this novel effect of Abeta could be useful for the discovery of anti AD drugs capable of blocking these "Abeta perforates". In addition, we demonstrate that peptides that block Abeta neurotoxicity also slow or prevent the membrane-perforating action of Abeta.

  9. Alzheimer's Toxic Amyloid Beta Oligomers: Unwelcome Visitors to the Na/K ATPase alpha3 Docking Station.

    Science.gov (United States)

    DiChiara, Thomas; DiNunno, Nadia; Clark, Jeffrey; Bu, Riana Lo; Cline, Erika N; Rollins, Madeline G; Gong, Yuesong; Brody, David L; Sligar, Stephen G; Velasco, Pauline T; Viola, Kirsten L; Klein, William L

    2017-03-01

    Toxic amyloid beta oligomers (AβOs) are known to accumulate in Alzheimer's disease (AD) and in animal models of AD. Their structure is heterogeneous, and they are found in both intracellular and extracellular milieu. When given to CNS cultures or injected ICV into non-human primates and other non-transgenic animals, AβOs have been found to cause impaired synaptic plasticity, loss of memory function, tau hyperphosphorylation and tangle formation, synapse elimination, oxidative and ER stress, inflammatory microglial activation, and selective nerve cell death. Memory loss and pathology in transgenic models are prevented by AβO antibodies, while Aducanumab, an antibody that targets AβOs as well as fibrillar Aβ, has provided cognitive benefit to humans in early clinical trials. AβOs have now been investigated in more than 3000 studies and are widely thought to be the major toxic form of Aβ. Although much has been learned about the downstream mechanisms of AβO action, a major gap concerns the earliest steps: How do AβOs initially interact with surface membranes to generate neuron-damaging transmembrane events? Findings from Ohnishi et al (PNAS 2005) combined with new results presented here are consistent with the hypothesis that AβOs act as neurotoxins because they attach to particular membrane protein docks containing Na/K ATPase-α3, where they inhibit ATPase activity and pathologically restructure dock composition and topology in a manner leading to excessive Ca++ build-up. Better understanding of the mechanism that makes attachment of AβOs to vulnerable neurons a neurotoxic phenomenon should open the door to therapeutics and diagnostics targeting the first step of a complex pathway that leads to neural damage and dementia.

  10. Impaired memory is more closely associated with brain beta-amyloid than leukoaraiosis in hypertensive patients with cognitive symptoms.

    Directory of Open Access Journals (Sweden)

    Eric E Smith

    Full Text Available Hypertension is the strongest modifiable risk factor for subcortical ischemic changes and is also a risk factor for Alzheimer's dementia. We used neuroimaging to investigate the pathological basis of early cognitive symptoms in patients with hypertension.In this cross-sectional cohort study 67 patients age >60 years with hypertension and Clinical Dementia Rating scale score of 0.5 without dementia, and without history of symptomatic stroke, underwent MRI for measurement of subcortical vascular changes and positron emission tomography (PET scan with Pittsburgh Compound B (PiB-PET to detect beta-amyloid deposition. These imaging measures were related to neuropsychological tests of memory, executive function and processing speed.Mean age was 75.0 (standard deviation, SD, 7.3. Mean neuropsychological Z scores were: episodic memory -0.63 (SD 1.23, executive function -0.40 (SD 1.10, processing speed -0.24 (SD 0.88; 22 of the 67 subjects met criteria for mild cognitive impairment (MCI and the remaining 45 subjects had subjective cognitive concerns only. In multivariable models adjusting for age and years of education, each 0.1 unit increase in mean cortical PiB-PET binding was associated with 0.14 lower mean Z score for episodic memory (95% CI -0.28 to -0.01. This means that for every 0.1 unit increase in mean cortical PiB-PET, episodic memory was 0.14 standard deviations lower. White matter hyperintensity volume, silent brain infarcts and microbleeds were not associated with neuropsychological test scores.Episodic memory was prominently affected in hypertensive participants with MCI or subjective cognitive concerns, and was associated with PiB-PET binding. This suggests a prominent role for Alzheimer pathology in cognitive impairment even in hypertensive participants at elevated risk for vascular cognitive impairment.

  11. Neuroprotective Effect of Fisetin Against Amyloid-Beta-Induced Cognitive/Synaptic Dysfunction, Neuroinflammation, and Neurodegeneration in Adult Mice.

    Science.gov (United States)

    Ahmad, Ashfaq; Ali, Tahir; Park, Hyun Young; Badshah, Haroon; Rehman, Shafiq Ur; Kim, Myeong Ok

    2017-04-01

    Alzheimer's disease (AD) is a devastating and progressive neurodegenerative disease and is characterized pathologically by the accumulation of amyloid beta (Aβ) and the hyperphosphorylation of tau proteins in the brain. The deposition of Aβ aggregates triggers synaptic dysfunction, hyperphosphorylation of tau, and neurodegeneration, which lead to cognitive disorders. Here, we investigated the neuroprotective effect of fisetin in the Aβ 1-42 mouse model of AD. Single intracerebroventricular injections of Aβ 1-42 (3 μl/5 min/mouse) markedly induced memory/synaptic deficits, neuroinflammation, and neurodegeneration. Intraperitoneal injections of fisetin at a dose of 20 mg/kg/day for 2 weeks starting 24 h after Aβ 1-42 injection significantly decreased the Aβ 1-42 -induced accumulation of Aβ, BACE-1 expression, and hyperphosphorylation of tau protein at serine 413. Fisetin treatment also markedly reversed Aβ 1-42 -induced synaptic dysfunction by increasing the levels of both presynaptic (SYN and SNAP-25) and postsynaptic proteins (PSD-95, SNAP-23, p-GluR1 (Ser 845), p-CREB (Ser 133) and p-CAMKII (Thr 286) and ultimately improved mouse memory, as observed in the Morris water maze test. Fisetin significantly activated p-PI3K, p-Akt (Ser 473), and p-GSK3β (Ser 9) expression in Aβ 1-42 -treated mice. Moreover, fisetin prevented neuroinflammation by suppressing various activated neuroinflammatory mediators and gliosis; it also suppressed the apoptotic neurodegeneration triggered by Aβ 1-42 injections in the mouse hippocampus. Fluorojade-B and immunohistochemical staining for caspase-3 revealed that fisetin prevented neurodegeneration in Aβ 1-42 -treated mice. Our results suggest that fisetin has a potent neuroprotective effect against Aβ 1-42 -induced neurotoxicity. These results demonstrate that polyphenolic flavonoids such as fisetin could be a beneficial, effective and safe neuroprotective agent for preventing neurological disorders such as AD.

  12. Reduced amyloidogenic processing of the amyloid beta-protein precursor by the small-molecule Differentiation Inducing Factor-1.

    Science.gov (United States)

    Myre, Michael A; Washicosky, Kevin; Moir, Robert D; Tesco, Giuseppina; Tanzi, Rudolph E; Wasco, Wilma

    2009-04-01

    The detection of cell cycle proteins in Alzheimer's disease (AD) brains may represent an early event leading to neurodegeneration. To identify cell cycle modifiers with anti-Abeta properties, we assessed the effect of Differentiation-Inducing Factor-1 (DIF-1), a unique, small-molecule from Dictyostelium discoideum, on the proteolysis of the amyloid beta-protein precursor (APP) in a variety of different cell types. We show that DIF-1 slows cell cycle progression through G0/G1 that correlates with a reduction in cyclin D1 protein levels. Western blot analysis of DIF-treated cells and conditioned medium revealed decreases in the levels of secreted APP, mature APP, and C-terminal fragments. Assessment of conditioned media by sandwich ELISA showed reduced levels of Abeta40 and Abeta42, also demonstrating that treatment with DIF-1 effectively decreases the ratio of Abeta42 to Abeta40. In addition, DIF-1 significantly diminished APP phosphorylation at residue T668. Interestingly, site-directed mutagenesis of APP residue Thr668 to alanine or glutamic acid abolished the effect of DIF-1 on APP proteolysis and restored secreted levels of Abeta. Finally, DIF-1 prevented the accumulation of APP C-terminal fragments induced by the proteasome inhibitor lactacystin, and calpain inhibitor N-acetyl-leucyl-leucyl-norleucinal (ALLN). Our findings suggest that DIF-1 affects G0/G1-associated amyloidogenic processing of APP by a gamma-secretase-, proteasome- and calpain-insensitive pathway, and that this effect requires the presence of residue Thr668.

  13. Cortical Amyloid Beta in Cognitively Normal Elderly Adults is Associated with Decreased Network Efficiency within the Cerebro-Cerebellar System.

    Science.gov (United States)

    Steininger, Stefanie C; Liu, Xinyang; Gietl, Anton; Wyss, Michael; Schreiner, Simon; Gruber, Esmeralda; Treyer, Valerie; Kälin, Andrea; Leh, Sandra; Buck, Alfred; Nitsch, Roger M; Prüssmann, Klaas P; Hock, Christoph; Unschuld, Paul G

    2014-01-01

    Deposition of cortical amyloid beta (Aβ) is a correlate of aging and a risk factor for Alzheimer disease (AD). While several higher order cognitive processes involve functional interactions between cortex and cerebellum, this study aims to investigate effects of cortical Aβ deposition on coupling within the cerebro-cerebellar system. We included 15 healthy elderly subjects with normal cognitive performance as assessed by neuropsychological testing. Cortical Aβ was quantified using (11)carbon-labeled Pittsburgh compound B positron-emission-tomography late frame signals. Volumes of brain structures were assessed by applying an automated parcelation algorithm to three dimensional magnetization-prepared rapid gradient-echo T1-weighted images. Basal functional network activity within the cerebro-cerebellar system was assessed using blood-oxygen-level dependent resting state functional magnetic resonance imaging at the high field strength of 7 T for measuring coupling between cerebellar seeds and cerebral gray matter. A bivariate regression approach was applied for identification of brain regions with significant effects of individual cortical Aβ load on coupling. Consistent with earlier reports, a significant degree of positive and negative coupling could be observed between cerebellar seeds and cerebral voxels. Significant positive effects of cortical Aβ load on cerebro-cerebellar coupling resulted for cerebral brain regions located in inferior temporal lobe, prefrontal cortex, hippocampus, parahippocampal gyrus, and thalamus. Our findings indicate that brain amyloidosis in cognitively normal elderly subjects is associated with decreased network efficiency within the cerebro-cerebellar system. While the identified cerebral regions are consistent with established patterns of increased sensitivity for Aβ-associated neurodegeneration, additional studies are needed to elucidate the relationship between dysfunction of the cerebro-cerebellar system and risk for AD.

  14. Direct exposure of guinea pig CNS to human luteinizing hormone increases cerebrospinal fluid and cerebral beta amyloid levels.

    Science.gov (United States)

    Wahjoepramono, Eka J; Wijaya, Linda K; Taddei, Kevin; Bates, Kristyn A; Howard, Matthew; Martins, Georgia; deRuyck, Karl; Matthews, Paul M; Verdile, Giuseppe; Martins, Ralph N

    2011-01-01

    Luteinizing hormone (LH) has been shown to alter the metabolism of beta amyloid (Aβ), a key protein in Alzheimer's disease (AD) pathogenesis. While LH and components required for LH receptor signalling are present in the brain, their role in the CNS remains unclear. In vitro, LH has been shown to facilitate neurosteroid production and alter Aβ metabolism. However, whether LH can directly modulate cerebral Aβ levels in vivo has not previously been studied. In this study, we investigated the effect of chronic administration of LH to the guinea pig CNS on cerebral Aβ levels. Gonadectomised male animals were administered, via cortical placement, either placebo or LH slow-release pellets. At 14 and 28 days after treatment, animals were sacrificed. Brain, plasma and CSF were collected and Aβ levels measured via ELISA. Levels of the Aβ precursor protein (APP) and the neurosteroidogenic enzyme cytochrome P450 side-chain cleavage enzyme (P450scc) were also assayed. An increase in CSF Aβ40 levels was observed 28 days following treatment. These CSF data also reflected changes in Aβ40 levels observed in brain homogenates. No change was observed in plasma Aβ40 levels but APP and its C-terminal fragments (APP-CTF) were significantly increased in response to LH exposure. Protein expression of P450scc was increased after 28 days of LH exposure, suggesting activation of the LH receptor. These data indicate that direct exposure of guinea pig CNS to LH results in altered brain Aβ levels, perhaps due to altered APP expression/metabolism. Copyright © 2011 S. Karger AG, Basel.

  15. [Molecular cloning of activin betaA subunit mature peptide from peafowl and its application in taxonomy and phylogeny].

    Science.gov (United States)

    Zou, Fang-Dong; Tong, Xin-Xin; Yue, Bi-Song

    2005-03-01

    The sequences of activin gene betaA subunit mature peptide have been amplified from white peafowl, blue peafowl (pavo cristatus) and green peafowl (pavo muticus) genomic DNA by polymerase chain reaction (PCR) with a pair of degenerate primers. The target fragments were cloned into the vector pMD18-T and sequenced. The length of activin gene betaA subunit mature peptide is 345bp, which encoded a peptide of 115 amino acid residues. Sequence analysis of activin gene betaA subunit mature peptide demonstrated that the identity of nucleotide is 98.0% between blue peaflowl and green peafowl, and the identity of that is 98.8% between blue peaflowl and white peafow. Sequences comparison in NCBI revealed that the sequences of activin gene betaA subunit mature peptides of different species are highly conserved during evolution process. In addition, the restriction enzyme map of activins is high similar between white peafowl and blue peafowl. Phylogenetic tree was constructed with Mega 2 and Clustalxldx software. The result showed that white peafowl has a closer relationship to blue peafowl than to green peafowl. Considered the nucleotide differences of peafowls' activin gene betaA subunit mature peptides, a highly conserved region, we supported that white peafowl was derived from blue peafowl, and it is more possible the hybrid but just the product of color mutation, or maybe as a subspecies of Pavo genus.

  16. Nanoparticles and amyloid systems: A fatal encounter?

    Energy Technology Data Exchange (ETDEWEB)

    Abel, Bernd [Leibniz Institute of Surface Modification, Chemical Department, Permoserstr. 15, D-04318 Leipzig, Germany and Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, Linnéstr. 3, D-04103 Leipzig (Germany)

    2014-10-06

    Nanoparticles (NPs) are used in many products of our daily life, however, there has been concern that they may also be harmful to human health. Recently NPs have been found to accelerate the fibrillation kinetics of amyloid systems. In the past this has been preliminarily attributed to a nucleation effect. Nanoparticle surfaces and interfaces appear to limit the degrees of freedom of amyloid systems (i.e., peptides and proteins) due to a phase space constraint such that rapid cross-beta structures are formed faster than without interface interactions and in turn fibril formation is enhanced significantly. Here we explore if lipid bilayers in the form of liposomes (140nm) also accelerate fibril formation for amyloid systems. We have investigated a fragment NNFGAIL of the Human islet amyloid polypeptide (hIAPP) in contact with 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) liposomes in aqueous solution. We found that the lipid bilayer vesicles do accelerate fibril formation in time-resolved off-line detected atomic force microscopy experiments. Characteristic Thioflavine-T fluorescence on the same structures verify that the structures consist of aggregated peptides in a typical cross-β-structure arrangement.

  17. Chirality and chiroptical properties of amyloid fibrils.

    Science.gov (United States)

    Dzwolak, Wojciech

    2014-09-01

    Chirality of amyloid fibrils-linear beta-sheet-rich aggregates of misfolded protein chains-often manifests in morphological traits such as helical twist visible in atomic force microscopy and in chiroptical properties accessible to vibrational circular dichroism (VCD). According to recent studies the relationship between molecular chirality of polypeptide building blocks and superstructural chirality of amyloid fibrils may be more intricate and less deterministic than previously assumed. Several puzzling experimental findings have put into question earlier intuitive ideas on: 1) the bottom-up chirality transfer upon amyloidogenic self-assembly, and 2) the structural origins of chiroptical properties of protein aggregates. For example, removal of a single amino acid residue from an amyloidogenic all-L peptide was shown to reverse handedness of fibrils. On the other hand, certain types of amyloid aggregates revealed surprisingly strong VCD spectra with the sign and shape dependent on the conditions of fibrillation. Hence, microscopic and chiroptical studies have highlighted chirality as one more aspect of polymorphism of amyloid fibrils. This brief review is intended to outline the current state of research on amyloid-like fibrils from the perspective of their structural and superstructural chirality and chiroptical properties. © 2014 Wiley Periodicals, Inc.

  18. Exendin-4, a glucagon-like peptide 1 receptor agonist, protects against amyloidpeptide-induced impairment of spatial learning and memory in rats.

    Science.gov (United States)

    Jia, Xiao-Tao; Ye-Tian; Yuan-Li; Zhang, Ge-Juan; Liu, Zhi-Qin; Di, Zheng-Li; Ying, Xiao-Ping; Fang, Yan; Song, Er-Fei; Qi, Jin-Shun; Pan, Yan-Fang

    2016-05-15

    Type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) share specific molecular mechanisms, and agents with proven efficacy in one may be useful against the other. The glucagon-like peptide-1 (GLP-1) receptor agonist exendin-4 has similar properties to GLP-1 and is currently in clinical use for T2DM treatment. Thus, this study was designed to characterize the effects of exendin-4 on the impairment of learning and memory induced by amyloid protein (Aβ) and its probable molecular underlying mechanisms. The results showed that (1) intracerebroventricular (i.c.v.) injection of Aβ1-42 resulted in a significant decline of spatial learning and memory of rats in water maze tests; (2) pretreatment with exendin-4 effectively and dose-dependently protected against the Aβ1-42-induced impairment of spatial learning and memory; (3) exendin-4 treatment significantly decreased the expression of Bax and cleaved caspase-3 and increased the expression of Bcl2 in Aβ1-42-induced Alzheimer's rats. The vision and swimming speed of the rats among all groups in the visible platform tests did not show any difference. These findings indicate that systemic pretreatment with exendin-4 can effectively prevent the behavioral impairment induced by neurotoxic Aβ1-42, and the underlying protective mechanism of exendin-4 may be involved in the Bcl2, Bax and caspase-3 pathways. Thus, the application of exendin-4 or the activation of its signaling pathways may be a promising strategy to ameliorate the degenerative processes observed in AD. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Cerebral Amyloid Angiopathy

    Directory of Open Access Journals (Sweden)

    Mahmut Edip Gürol

    2009-03-01

    Full Text Available Cerebral amyloid angiopathy (CAA is characterized by the accumulation of amyloid beta-peptides (Ab in the walls of leptomeningeal arteries, arterioles, and veins. Despite the fact that these pathological changes were first described in 1909, major advancement in our understanding of the clinicoradiological manifestations, neurobiology, and course of CAA has occurred only during the last 30 years. No significant associations have been shown between CAA and other systemic/visceral amyloidoses or vascular risk factors, including hypertension. CAA is well known as the most common cause of spontaneous and anticoagulant-related lobar parenchymal ICH in the elderly. It also causes lobar cerebral microbleeds (CMBs, small dot-like dark susceptibility artifacts visible with gradient recalled echo (GRE-magnetic resonance imaging (MRI. CMBs are important markers of disease severity and predictors of CAA progression. Amyloid angiopathy is also a common cause of ischemic microvascular white matter disease (WMD and deep cerebral infarctions. Such WMD is defined as subcortical and periventricular white matter changes without obvious infarction, as well as a dark appearance on computerized tomography (CT and a bright appearance on fluid attenuated inversion recovery (FLAIR-MRI. CAA-related vascular dysfunction, with its hemorrhagic and ischemic complications, is a recognized contributor to vascular cognitive impairment in the elderly, an independent effect that is synergistically increased by Alzheimer pathologies, such as plaques and tangles. A set of clinicoradiological criteria was established for the accurate diagnosis of CAA. According to the Boston Criteria, patients aged 55 years and older with multiple hemorrhages (on CT or GRE-MRI restricted to the lobar, cortical, or corticosubcortical regions (cerebellar hemorrhage allowed are diagnosed as probable CAA when no other etiology is found; a single hemorrhage in the same region is classified as possible

  20. Generation and Partial Characterization of Rabbit Monoclonal Antibody to AmyloidPeptide 1-37 (Aβ37).

    Science.gov (United States)

    Mehta, Pankaj D; Blain, Jean-Francois; Freeman, Emily A; Patrick, Bruce A; Barshatzky, Marc; Hrdlicka, Lori A; Mehta, Sangita P; Frackowiak, Janusz; Mazur-Kolecka, Bozena; Wegiel, Jerzy; Patzke, Holger; Miller, David L

    2017-01-01

    Secreted soluble amyloid-β 1-37 (Aβ37) peptide is one of the prominent Aβ forms next to Aβ40, and is found in cerebrospinal fluid (CSF) and blood. Recent studies have shown the importance of quantitation of CSF Aβ37 levels in combination with Aβ38, Aβ40, and Aβ42 to support the diagnosis of patients with probable Alzheimer's disease (AD), and the value of antibody to Aβ37 to facilitate drug discovery studies. However, the availability of reliable and specific monoclonal antibody to Aβ37 is very limited. Our aims were: 1) to generate and partially characterize rabbit monoclonal antibody (RabmAb) to Aβ37, and 2) to determine whether the antibody detects changes in Aβ37 levels produced by a γ-secretase modulator (GSM). Our generated RabmAb to Aβ37 was found to be specific to Aβ37, since it did not react with Aβ36, Aβ38, Aβ39, Aβ40, and Aβ42 in an ELISA or immunoblotting. The epitope of the antibody was contained in the seven C-terminal residues of Aβ37. The antibody was sensitive enough to measure CSF and plasma Aβ37 levels in ELISA. Immunohistological studies showed the presence of Aβ37-positive deposits in the brain of AD, and Down syndrome persons diagnosed with AD. Our studies also showed that the antibody detected Aβ37 increases in CSF and brains of rodents following treatment with a GSM. Thus, our antibody can be widely applied to AD research, and in a panel based approach it may have potential to support the diagnosis of probable AD, and in testing the effect of GSMs to target AD.

  1. Selective inhibition of phosphodiesterases 4, 5 and 9 induces HSP20 phosphorylation and attenuates amyloid beta 1-42 mediated cytotoxicity

    OpenAIRE

    Cameron, Ryan T.; Whiteley, Ellanor; Day, Jon P.; Parachikova, Anna I.; Baillie, George S.

    2017-01-01

    Phosphodiesterase (PDE) inhibitors are currently under evaluation as agents that may facilitate the improvement of cognitive impairment associated with Alzheimer's disease. Our aim was to determine whether inhibitors of PDEs 4, 5 and 9 could alleviate the cytotoxic effects of amyloid beta 1?42 (A?1?42) via a mechanism involving the small heatshock protein HSP20. We show that inhibition of PDEs 4, 5 and 9 but not 3 induces the phosphorylation of HSP20 which, in turn, increases the colocalisati...

  2. 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.

  3. Expanding the peptide beta-turn in alphagamma hybrid sequences: 12 atom hydrogen bonded helical and hairpin turns.

    Science.gov (United States)

    Chatterjee, Sunanda; Vasudev, Prema G; Raghothama, Srinivasarao; Ramakrishnan, Chandrasekharan; Shamala, Narayanaswamy; Balaram, Padmanabhan

    2009-04-29

    Hybrid peptide segments containing contiguous alpha and gamma amino acid residues can form C(12) hydrogen bonded turns which may be considered as backbone expanded analogues of C(10) (beta-turns) found in alphaalpha segments. Exploration of the regular hydrogen bonded conformations accessible for hybrid alphagamma sequences is facilitated by the use of a stereochemically constrained gamma amino acid residue gabapentin (1-aminomethylcyclohexaneacetic acid, Gpn), in which the two torsion angles about C(gamma)-C(beta) (theta(1)) and C(beta)-C(alpha) (theta(2)) are predominantly restricted to gauche conformations. The crystal structures of the octapeptides Boc-Gpn-Aib-Gpn-Aib-Gpn-Aib-Gpn-Aib-OMe (1) and Boc-Leu-Phe-Val-Aib-Gpn-Leu-Phe-Val-OMe (2) reveal two distinct conformations for the Aib-Gpn segment. Peptide 1 forms a continuous helix over the Aib(2)-Aib(6) segment, while the peptide 2 forms a beta-hairpin structure stabilized by four cross-strand hydrogen bonds with the Aib-Gpn segment forming a nonhelical C(12) turn. The robustness of the helix in peptide 1 in solution is demonstrated by NMR methods. Peptide 2 is conformationally fragile in solution with evidence of beta-hairpin conformations being obtained in methanol. Theoretical calculations permit delineation of the various C(12) hydrogen bonded structures which are energetically feasible in alphagamma and gammaalpha sequences.

  4. pH-dependence of the specific binding of Cu(II) and Zn(II) ions to the amyloidpeptide

    International Nuclear Information System (INIS)

    Ghalebani, Leila; Wahlström, Anna; Danielsson, Jens; Wärmländer, Sebastian K.T.S.; Gräslund, Astrid

    2012-01-01

    Highlights: ► Cu(II) and Zn(II) display pH-dependent binding to the Aβ(1–40) peptide. ► At pH 7.4 both metal ions display residue-specific binding to the Aβ peptide. ► At pH 5.5 the binding specificity is lost for Zn(II). ► Differential Cu(II) and Zn(II) binding may help explain metal-induced AD toxicity. -- Abstract: Metal ions like Cu(II) and Zn(II) are accumulated in Alzheimer’s disease amyloid plaques. The amyloid-β (Aβ) peptide involved in the disease interacts with these metal ions at neutral pH via ligands provided by the N-terminal histidines and the N-terminus. The present study uses high-resolution NMR spectroscopy to monitor the residue-specific interactions of Cu(II) and Zn(II) with 15 N- and 13 C, 15 N-labeled Aβ(1–40) peptides at varying pH levels. At pH 7.4 both ions bind to the specific ligands, competing with one another. At pH 5.5 Cu(II) retains its specific histidine ligands, while Zn(II) seems to lack residue-specific interactions. The low pH mimics acidosis which is linked to inflammatory processes in vivo. The results suggest that the cell toxic effects of redox active Cu(II) binding to Aβ may be reversed by the protective activity of non-redox active Zn(II) binding to the same major binding site under non-acidic conditions. Under acidic conditions, the protective effect of Zn(II) may be decreased or changed, since Zn(II) is less able to compete with Cu(II) for the specific binding site on the Aβ peptide under these conditions.

  5. Soluble γ-secretase modulators selectively inhibit the production of the 42-amino acid amyloid β peptide variant and augment the production of multiple carboxy-truncated amyloid β species.

    Science.gov (United States)

    Wagner, Steven L; Zhang, Can; Cheng, Soan; Nguyen, Phuong; Zhang, Xulun; Rynearson, Kevin D; Wang, Rong; Li, Yueming; Sisodia, Sangram S; Mobley, William C; Tanzi, Rudolph E

    2014-02-04

    Alzheimer's disease (AD) is characterized pathologically by an abundance of extracellular neuritic plaques composed primarily of the 42-amino acid amyloid β peptide variant (Aβ42). In the majority of familial AD (FAD) cases, e.g., those harboring mutations in presenilin 1 (PS1), there is a relative increase in the levels of Aβ42 compared to the levels of Aβ40. We previously reported the characterization of a series of aminothiazole-bridged aromates termed aryl aminothiazole γ-secretase modulators or AGSMs [Kounnas, M. Z., et al. (2010) Neuron 67, 769-780] and showed their potential for use in the treatment of FAD [Wagner, S. L., et al. (2012) Arch. Neurol. 69, 1255-1258]. Here we describe a series of GSMs with physicochemical properties improved compared to those of AGSMs. Specific heterocycle replacements of the phenyl rings in AGSMs provided potent molecules with improved aqueous solubilities. A number of these soluble γ-secretase modulators (SGSMs) potently lowered Aβ42 levels without inhibiting proteolysis of Notch or causing accumulation of amyloid precursor protein carboxy-terminal fragments, even at concentrations approximately 1000-fold greater than their IC50 values for reducing Aβ42 levels. The effects of one potent SGSM on Aβ peptide production were verified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry, showing enhanced production of a number of carboxy-truncated Aβ species. This SGSM also inhibited Aβ42 peptide production in a highly purified reconstituted γ-secretase in vitro assay system and retained the ability to modulate γ-secretase-mediated proteolysis in a stably transfected cell culture model overexpressing a human PS1 mutation validating the potential for use in FAD.

  6. GMP-compliant automated synthesis of [{sup 18}F]AV-45 (Florbetapir F 18) for imaging {beta}-amyloid plaques in human brain

    Energy Technology Data Exchange (ETDEWEB)

    Yao, C.-H. [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Lin, K.-J. [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hua 1st Road, Kweishan, Taoyuan 333, Taiwan (China); Weng, C.-C. [Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hua 1st Road, Kweishan, Taoyuan 333, Taiwan (China); Hsiao, I.-T. [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hua 1st Road, Kweishan, Taoyuan 333, Taiwan (China); Ting, Y.-S. [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Yen, T.-C. [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hua 1st Road, Kweishan, Taoyuan 333, Taiwan (China); Jan, T.-R. [Department and Graduate Institute of Veterinary Medicine, National Taiwan University, Taipei, Taiwan (China); Skovronsky, Daniel [Avid Radiopharmaceuticals, Inc., Philadelphia, PA 19104 (United States); Kung, M.-P. [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Wey, S.-P., E-mail: spwey@mail.cgu.edu.t [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hua 1st Road, Kweishan, Taoyuan 333, Taiwan (China)

    2010-12-15

    We report herein the Good Manufacturing Practice (GMP)-compliant automated synthesis of {sup 18}F-labeled styrylpyridine, AV-45 (Florbetapir), a novel tracer for positron emission tomography (PET) imaging of {beta}-amyloid (A{beta}) plaques in the brain of Alzheimer's disease patients. [{sup 18}F]AV-45 was prepared in 105 min using a tosylate precursor with Sumitomo modules for radiosynthesis under GMP-compliant conditions. The overall yield was 25.4{+-}7.7% with a final radiochemical purity of 95.3{+-}2.2% (n=19). The specific activity of [{sup 18}F]AV-45 reached as high as 470{+-}135 TBq/mmol (n=19). The present studies show that [{sup 18}F]AV-45 can be manufactured under GMP-compliant conditions and could be widely available for routine clinical use.

  7. Aggregation, impaired degradation and immunization targeting of amyloid-beta dimers in Alzheimer’s disease: a stochastic modelling approach

    Directory of Open Access Journals (Sweden)

    Proctor Carole J

    2012-07-01

    Full Text Available Abstract Background Alzheimer’s disease (AD is the most frequently diagnosed neurodegenerative disorder affecting humans, with advanced age being the most prominent risk factor for developing AD. Despite intense research efforts aimed at elucidating the precise molecular underpinnings of AD, a definitive answer is still lacking. In recent years, consensus has grown that dimerisation of the polypeptide amyloid-beta (Aß, particularly Aß42, plays a crucial role in the neuropathology that characterise AD-affected post-mortem brains, including the large-scale accumulation of fibrils, also referred to as senile plaques. This has led to the realistic hope that targeting Aß42 immunotherapeutically could drastically reduce plaque burden in the ageing brain, thus delaying AD onset or symptom progression. Stochastic modelling is a useful tool for increasing understanding of the processes underlying complex systems-affecting disorders such as AD, providing a rapid and inexpensive strategy for testing putative new therapies. In light of the tool’s utility, we developed computer simulation models to examine Aß42 turnover and its aggregation in detail and to test the effect of immunization against Aß dimers. Results Our model demonstrates for the first time that even a slight decrease in the clearance rate of Aß42 monomers is sufficient to increase the chance of dimers forming, which could act as instigators of protofibril and fibril formation, resulting in increased plaque levels. As the process is slow and levels of Aβ are normally low, stochastic effects are important. Our model predicts that reducing the rate of dimerisation leads to a significant reduction in plaque levels and delays onset of plaque formation. The model was used to test the effect of an antibody mediated immunological response. Our results showed that plaque levels were reduced compared to conditions where antibodies are not present. Conclusion Our model supports the current

  8. Multielement analysis of swiss mice brains with Alzheimer's disease induced by beta amyloid oligomers using a portable total reflection X-ray fluorescence system

    International Nuclear Information System (INIS)

    Almeida, Danielle S.; Brigido, Matheus M.; Anjos, Marcelino J.; Ferreira, Sergio S.; Souza, Amanda S.; Lopes, Ricardo T.

    2017-01-01

    Alzheimer's disease (AD) is a progressive dementia that, in early stages, manifests as a profound inability to form new memories. The pathological features of AD include β-amyloid (Aβ) plaques, intracellular neurofibrillary tangles, loss of neurons and synapses, and activation of glia cells. Recently, several groups have raised the 'metal hypothesis' of AD. Metal ions, such as Cu and Zn, have been demonstrated to modulate amyloid aggregation along different pathways. Extensive research has been conducted on the effects of metals on Aβ aggregation and all of them have shown that both Cu and Zn accelerate the aggregation by shortening, or eliminating, the lag phase associated with the amyloid fibrillation process. The metal ions mentioned previously may have an important impact on the protein misfolding and the progression of the neurodegenerative process. The TXRF technique is very important, because can be used to identify and quantify trace elements present in the sample at very low concentrations (μg.g"-"1). In this work, three groups of females were studied: control, AD10 and AD100. The groups AD10 and AD100 were given a single intracerebroventricular injection of 10 pmol and 100 pmol of oligomers of β-amyloid peptide respectively to be induced AD. The TXRF measurements were performed using a portable total reflection X-ray fluorescence system developed in the Laboratory of Nuclear Instrumentation (LIN/UFRJ) that uses an X-ray tube with a molybdenum anode operating at 40 kV and 500 mA used for the excitation and a detector Si-PIN with energy resolution of 145 eV at 200 eV. It was possible to determine the concentrations of the following elements: P, S, K, Fe, Cu, Zn and Rubidium. Results showed differences in the elemental concentration in some brain regions between the AD groups and the control group. (author)

  9. Multielement analysis of swiss mice brains with Alzheimer's disease induced by beta amyloid oligomers using a portable total reflection X-ray fluorescence system

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Danielle S.; Brigido, Matheus M.; Anjos, Marcelino J.; Ferreira, Sergio S.; Souza, Amanda S.; Lopes, Ricardo T., E-mail: ricardo@lin.ufrj.br, E-mail: marcelin@uerj.br, E-mail: amandass@bioqmed.ufrj.br, E-mail: ferreira@bioqmed.ufrj.br, E-mail: amandass@bioqmed.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil); Instituto de Fisica Armando Dias Tavares (Brazil)

    2017-11-01

    Alzheimer's disease (AD) is a progressive dementia that, in early stages, manifests as a profound inability to form new memories. The pathological features of AD include β-amyloid (Aβ) plaques, intracellular neurofibrillary tangles, loss of neurons and synapses, and activation of glia cells. Recently, several groups have raised the 'metal hypothesis' of AD. Metal ions, such as Cu and Zn, have been demonstrated to modulate amyloid aggregation along different pathways. Extensive research has been conducted on the effects of metals on Aβ aggregation and all of them have shown that both Cu and Zn accelerate the aggregation by shortening, or eliminating, the lag phase associated with the amyloid fibrillation process. The metal ions mentioned previously may have an important impact on the protein misfolding and the progression of the neurodegenerative process. The TXRF technique is very important, because can be used to identify and quantify trace elements present in the sample at very low concentrations (μg.g{sup -1}). In this work, three groups of females were studied: control, AD10 and AD100. The groups AD10 and AD100 were given a single intracerebroventricular injection of 10 pmol and 100 pmol of oligomers of β-amyloid peptide respectively to be induced AD. The TXRF measurements were performed using a portable total reflection X-ray fluorescence system developed in the Laboratory of Nuclear Instrumentation (LIN/UFRJ) that uses an X-ray tube with a molybdenum anode operating at 40 kV and 500 mA used for the excitation and a detector Si-PIN with energy resolution of 145 eV at 200 eV. It was possible to determine the concentrations of the following elements: P, S, K, Fe, Cu, Zn and Rubidium. Results showed differences in the elemental concentration in some brain regions between the AD groups and the control group. (author)

  10. Fetzima (levomilnacipran), a drug for major depressive disorder as a dual inhibitor for human serotonin transporters and beta-site amyloid precursor protein cleaving enzyme-1.

    Science.gov (United States)

    Rizvi, Syed Mohd Danish; Shaikh, Sibhghatulla; Khan, Mahiuddin; Biswas, Deboshree; Hameed, Nida; Shakil, Shazi

    2014-01-01

    Pharmacological management of Major Depressive Disorder includes the use of serotonin reuptake inhibitors which targets serotonin transporters (SERT) to increase the synaptic concentrations of serotonin. Beta-site amyloid precursor protein cleaving enzyme-1 (BACE-1) is responsible for amyloid β plaque formation. Hence it is an interesting target for Alzheimer's disease (AD) therapy. This study describes molecular interactions of a new Food and Drug Administration approved antidepressant drug named 'Fetzima' with BACE-1 and SERT. Fetzima is chemically known as levomilnacipran. The study has explored a possible link between the treatment of Depression and AD. 'Autodock 4.2' was used for docking study. The free energy of binding (ΔG) values for 'levomilnacipran-SERT' interaction and 'levomilnacipran-BACE1' interaction were found to be -7.47 and -8.25 kcal/mol, respectively. Levomilnacipran was found to interact with S438, known to be the most important amino acid residue of serotonin binding site of SERT during 'levomilnacipran-SERT' interaction. In the case of 'levomilnacipran-BACE1' interaction, levomilnacipran interacted with two very crucial aspartic acid residues of BACE-1, namely, D32 and D228. These residues are accountable for the cleavage of amyloid precursor protein and the subsequent formation of amyloid β plaques in AD brain. Hence, Fetzima (levomilnacipran) might act as a potent dual inhibitor of SERT and BACE-1 and expected to form the basis of a future dual therapy against depression and AD. It is an established fact that development of AD is associated with Major Depressive Disorder. Therefore, the design of new BACE-1 inhibitors based on antidepressant drug scaffolds would be particularly beneficial.

  11. The architecture of amyloid-like peptide fibrils revealed by X-ray scattering, diffraction and electron microscopy

    DEFF Research Database (Denmark)

    Langkilde, Annette Eva; Morris, Kyle L; Serpell, Louise C

    2015-01-01

    Structural analysis of protein fibrillation is inherently challenging. Given the crucial role of fibrils in amyloid diseases, method advancement is urgently needed. A hybrid modelling approach is presented enabling detailed analysis of a highly ordered and hierarchically organized fibril of the G......Structural analysis of protein fibrillation is inherently challenging. Given the crucial role of fibrils in amyloid diseases, method advancement is urgently needed. A hybrid modelling approach is presented enabling detailed analysis of a highly ordered and hierarchically organized fibril...

  12. Characterization of glucagon-like peptide-1 receptor beta-arrestin 2 interaction: a high-affinity receptor phenotype

    DEFF Research Database (Denmark)

    Jorgensen, Rasmus; Martini, Lene; Schwartz, Thue W

    2005-01-01

    To dissect the interaction between beta-arrestin ((beta)arr) and family B G protein-coupled receptors, we constructed fusion proteins between the glucagon-like peptide 1 receptor and (beta)arr2. The fusion constructs had an increase in apparent affinity selectively for glucagon, suggesting...... that (beta)arr2 interaction locks the receptor in a high-affinity conformation, which can be explored by some, but not all, ligands. The fusion constructs adopted a signaling phenotype governed by the tethered (beta)arr2 with an attenuated G protein-mediated cAMP signal and a higher maximal internalization...... of that which has previously been characterized for family A G protein-coupled receptors, suggesting similarities in the effect of (beta)arr interaction between family A and B receptors also at the molecular level....

  13. Induced dural lymphangiogenesis facilities soluble amyloid-beta clearance from brain in a transgenic mouse model of Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Ya-Ru Wen

    2018-01-01

    Full Text Available Impaired amyloid-β clearance from the brain is a core pathological event in Alzheimer's disease. The therapeutic effect of current pharmacotherapies is unsatisfactory, and some treatments cause severe side effects. The meningeal lymphatic vessels might be a new route for amyloid-β clearance. This study investigated whether promoting dural lymphangiogenesis facilitated the clearance of amyloid-β from the brain. First, human lymphatic endothelial cells were treated with 100 ng/mL recombinant human vascular endothelial growth factor-C (rhVEGF-C protein. Light microscopy verified that rhVEGF-C, a specific ligand for vascular endothelial growth factor receptor-3 (VEGFR-3, significantly promoted tube formation of human lymphatic endothelial cells in vitro. In an in vivo study, 200 μg/mL rhVEGF-C was injected into the cisterna magna of APP/PS1 transgenic mice, once every 2 days, four times in total. Immunofluorescence staining demonstrated high levels of dural lymphangiogenesis in Alzheimer's disease mice. One week after rhVEGF-C administration, enzyme-linked immunosorbent assay results showed that levels of soluble amyloid-β were decreased in cerebrospinal fluid and brain. The Morris water maze test demonstrated that spatial cognition was restored. These results indicate that the upregulation of dural lymphangiogenesis facilities amyloid-β clearance from the brain of APP/PS1 mice, suggesting the potential of the VEGF-C/VEGFR-3 signaling pathway as a therapeutic target for Alzheimer's disease.

  14. The host defense peptide beta-defensin 1 confers protection against Bordetella pertussis in newborn piglets.

    Science.gov (United States)

    Elahi, Shokrollah; Buchanan, Rachelle M; Attah-Poku, Sam; Townsend, Hugh G G; Babiuk, Lorne A; Gerdts, Volker

    2006-04-01

    Innate immunity plays an important role in protection against respiratory infections in humans and animals. Host defense peptides such as beta-defensins represent major components of innate immunity. We recently developed a novel porcine model of pertussis, an important respiratory disease of young children and infants worldwide. Here, we investigated the role of porcine beta-defensin 1 (pBD-1), a porcine defensin homologue of human beta-defensin 2, in conferring protection against respiratory infection with Bordetella pertussis. In this model, newborn piglets were fully susceptible to infection and developed severe bronchopneumonia. In contrast, piglets older than 4 weeks of age were protected against infection with B. pertussis. Protection was associated with the expression of pBD-1 in the upper respiratory tract. In fact, pBD-1 expression was developmentally regulated, and the absence of pBD-1 was thought to contribute to the increased susceptibility of newborn piglets to infection with B. pertussis. Bronchoalveolar lavage specimens collected from older animals as well as chemically synthesized pBD-1 displayed strong antimicrobial activity against B. pertussis in vitro. Furthermore, in vivo treatment of newborn piglets with only 500 mug pBD-1 at the time of challenge conferred protection against infection with B. pertussis. Interestingly, pBD-1 displayed no bactericidal activity in vitro against Bordetella bronchiseptica, a closely related natural pathogen of pigs. Our results demonstrate that host defense peptides play an important role in protection against pertussis and are essential in modulating innate immune responses against respiratory infections.

  15. Probing alpha-helical and beta-sheet structures of peptides at solid/liquid interfaces with SFG.

    Science.gov (United States)

    Chen, Xiaoyun; Wang, Jie; Sniadecki, Jason J; Even, Mark A; Chen, Zhan

    2005-03-29

    We demonstrated that sum frequency generation (SFG) vibrational spectroscopy can distinguish different secondary structures of proteins or peptides adsorbed at solid/liquid interfaces. The SFG spectrum for tachyplesin I at the polystyrene (PS)/solution interface has a fingerprint peak corresponding to the B1/B3 mode of the antiparallel beta-sheet. This peak disappeared upon the addition of dithiothreitol, which can disrupt the beta-sheet structure. The SFG spectrum indicative of the MSI594 alpha-helical structure was observed at the PS/MSI594 solution interface. This research validates SFG as a powerful technique for revealing detailed secondary structures of interfacial proteins and peptides.

  16. Development of a new family of conformationally restricted peptides as potent nucleators of beta-turns. Design, synthesis, structure, and biological evaluation of a beta-lactam peptide analogue of melanostatin.

    Science.gov (United States)

    Palomo, Claudio; Aizpurua, Jesus M; Benito, Ana; Miranda, José Ignacio; Fratila, Raluca M; Matute, Carlos; Domercq, Maria; Gago, Federico; Martin-Santamaria, Sonsoles; Linden, Anthony

    2003-12-31

    Novel enantiopure (i)-(beta-lactam)-(Gly)-(i+3) peptide models, defined by the presence of a central alpha-alkyl-alpha-amino-beta-lactam ring placed as the (i+1) residue, have been synthesized in a totally stereocontrolled way by alpha-alkylation of suitable N-[bis(trimethylsilyl)methyl]-beta-lactams. The structural properties of these beta-lactam pseudopeptides have been studied by X-ray crystallography, Molecular Dynamics simulation, and NOESY-restrained NMR simulated annealing techniques, showing a strong tendency to form stable type II or type II' beta-turns either in the solid state or in highly coordinating DMSO solutions. Tetrapeptide models containing syn- or anti-alpha,beta-dialkyl-alpha-amino-beta-lactam rings have also been synthesized and their conformations analyzed, revealing that alpha-alkyl substitution is essential for beta-turn stabilization. A beta-lactam analogue of melanostatin (PLG amide) has also been prepared, characterized as a type-II beta-turn in DMSO-d6 solution, and tested by competitive binding assay as a dopaminergic D2 modulator in rat neuron cultured cells, displaying moderate agonist activity in the micromolar concentration range. On the basis of these results, a novel peptidomimetic design concept, based on the separation of constraint and recognition elements, is proposed.

  17. Sequence-specific unusual (1-->2)-type helical turns in alpha/beta-hybrid peptides.

    Science.gov (United States)

    Prabhakaran, Panchami; Kale, Sangram S; Puranik, Vedavati G; Rajamohanan, P R; Chetina, Olga; Howard, Judith A K; Hofmann, Hans-Jörg; Sanjayan, Gangadhar J

    2008-12-31

    This article describes novel conformationally ordered alpha/beta-hybrid peptides consisting of repeating l-proline-anthranilic acid building blocks. These oligomers adopt a compact, right-handed helical architecture determined by the intrinsic conformational preferences of the individual amino acid residues. The striking feature of these oligomers is their ability to display an unusual periodic pseudo beta-turn network of nine-membered hydrogen-bonded rings formed in the forward direction of the sequence by 1-->2 amino acid interactions both in solid-state and in solution. Conformational investigations of several of these oligomers by single-crystal X-ray diffraction, solution-state NMR, and ab initio MO theory suggest that the characteristic steric and dihedral angle restraints exerted by proline are essential for stabilizing the unusual pseudo beta-turn network found in these oligomers. Replacing proline by the conformationally flexible analogue alanine (Ala) or by the conformationally more constrained alpha-amino isobutyric acid (Aib) had an adverse effect on the stabilization of this structural architecture. These findings increase the potential to design novel secondary structure elements profiting from the steric and dihedral angle constraints of the amino acid constituents and help to augment the conformational space available for synthetic oligomer design with diverse backbone structures.

  18. Effect of nanoparticles binding ß-amyloid peptide on nitric oxide production by cultured endothelial cells and macrophages

    Directory of Open Access Journals (Sweden)

    Orlando A

    2013-04-01

    Full Text Available Antonina Orlando,1 Francesca Re,1 Silvia Sesana,1 Ilaria Rivolta,1 Alice Panariti,1 Davide Brambilla,2 Julien Nicolas,2 Patrick Couvreur,2 Karine Andrieux,2 Massimo Masserini,1 Emanuela Cazzaniga1 1Department of Health Sciences, University of Milano-Bicocca, Monza, Italy; 2Institut Galien Paris Sud, University Paris-Sud, Châtenay-Malabry, France Background: As part of a project designing nanoparticles for the treatment of Alzheimer’s disease, we have synthesized and characterized a small library of nanoparticles binding with high affinity to the β-amyloid peptide and showing features of biocompatibility in vitro, which are important properties for administration in vivo. In this study, we focused on biocompatibility issues, evaluating production of nitric oxide by cultured human umbilical vein endothelial cells and macrophages, used as models of cells which would be exposed to nanoparticles after systemic administration. Methods: The nanoparticles tested were liposomes and solid lipid nanoparticles carrying phosphatidic acid or cardiolipin, and PEGylated poly(alkyl cyanoacrylate nanoparticles (PEG-PACA. We measured nitric oxide production using the Griess method as well as phosphorylation of endothelial nitric oxide synthase and intracellular free calcium, which are biochemically related to nitric oxide production. MTT viability tests and caspase-3 detection were also undertaken. Results: Exposure to liposomes did not affect the viability of endothelial cells at any concentration tested. Increased production of nitric oxide was detected only with liposomes carrying phosphatidic acid or cardiolipin at the highest concentration (120 µg/mL, together with increased synthase phosphorylation and intracellular calcium levels. Macrophages exposed to liposomes showed a slightly dose-dependent decrease in viability, with no increase in production of nitric oxide. Exposure to solid lipid nanoparticles carrying phosphatidic acid decreased viability in

  19. Effects of Yizhi Capsule (益智胶囊) on Learning and Memory Disorder and β-amyloid Peptide Induced Neurotoxicity in Rats

    Institute of Scientific and Technical Information of China (English)

    WU Hang-yu; XU Jiang-ping; LI Lin; ZHU Bai-hua

    2006-01-01

    Objective: To explore the effects of Yizhi Capsule (益智胶囊, YZC) on learning and memory disorder and β-amyloid peptide induced neurotoxicity in rats. Methods: Various doses of YZC were administered to Sprague-Dawley (SD) rats for 8 consecutive days, twice a day. On the 8th day of the experiment,scopolamine hydrobromide was intraperitoneally injected to every rat and Morris water maze test and shuttle dark avoidance test were carried out respectively to explore the changes of learning and memory capacities in the rats. Besides, after the cerebral cortical neurons of newborn SD rats aged within 3 days were cultured in vitro for 7 days, drug serum containing YZC was added to the cultured neurons before or after β amyloid peptide25-35 (Aβ25-35) intoxication to observe the protective effect of YZC on neurotoxicity by MTT assay and to determine the LDH content in the supernatant. Results: Compared with those untreated with YZC, the rats having received YZC treatment got superiority in shorter time of platform seeking in Morris water maze test,as well as elongated latent period and less times of error in shuttle dark avoidance test. On the cultured neurons, YZC drug serum could effectively increase the survival rate of Aβ25-35 intoxicated neurons and reduce the LDH contents in cultured supernatant. Conclusion: YZC has an action of improving learning and memory disorder, and good protective effect on Aβ25-35 induced neurotoxicity in SD rats.

  20. beta. -Endorphin and related peptides suppress phorbol myristate acetate-induced respiratory burst in human polymorphonuclear leukocytes

    Energy Technology Data Exchange (ETDEWEB)

    Diamant, M.; Henricks, P.A.J.; Nijkamp, F.P.; de Wied, D. (Univ. of Utrecht (Netherlands))

    1989-01-01

    In the present study, the immunomodulatory effect of {beta}-endorphin ({beta}-E) and shorter pro-opiomelancortin (POMC) fragments was evaluated by assessing their influence on respiratory burst in human polymorphonuclear leukocytes (PMN). The effect of the peptides on phorbol myristate acetate (PMA)-stimulated production of reactive oxygen metabolites was measured in a lucigenin-enhanced chemiluminescence (CL) assay. Both POMC peptides with opiate-like activity and their non-opioid derivatives were tested. With the exception of {alpha}-E, PMA-stimulated respiratory burst was suppressed by all POMC fragments tested. A U-shaped dose-response relation was observed. Doses lower than 10{sup {minus}17}M and higher than 10{sup {minus}8}M were without effect. {beta}-E and dT{beta}E both suppressed PMA-induced oxidative burst in human PMN at physiological concentrations. {gamma}-E and dT{gamma}E proved to be less potent inhibitors, reaching maximal effect at higher concentrations. DE{gamma}E exerted an even less pronounced but still significant suppressive effect at the concentration of 10{sup {minus}10}M. None of the endorphins tested was shown to affect resting oxidative metabolism in the PMN. The modulatory effects of the opioid peptides could not be blocked by the opioid antagonist naloxone.

  1. The antibacterial activity of peptides derived from human beta-2 glycoprotein I is inhibited by protein H and M1 protein from Streptococcus pyogenes

    NARCIS (Netherlands)

    Nilsson, Maria; Wasylik, Sylwia; Mörgelin, Matthias; Olin, Anders I.; Meijers, Joost C. M.; Derksen, Ronald H. W. M.; de Groot, Philip G.; Herwald, Heiko

    2008-01-01

    During the last years, the importance of antibacterial peptides has attracted considerable attention. We report here that peptides derived from the fifth domain of beta-2 glycoprotein I (beta(2)GPI), a human heparin binding plasma protein, have antibacterial activities against Gram-positive and

  2. Influence of scan duration on the accuracy of {beta}-amyloid PET with florbetaben in patients with Alzheimer's disease and healthy volunteers

    Energy Technology Data Exchange (ETDEWEB)

    Tiepolt, Solveig; Barthel, Henryk; Butzke, Daniel; Hesse, Swen; Patt, Marianne; Sabri, Osama [University of Leipzig, Department of Nuclear Medicine, Leipzig (Germany); Gertz, Hermann-Josef [University of Leipzig, Department of Psychiatry, Leipzig (Germany); Reininger, Cornelia [Bayer Pharma AG, Global Clinical Development, Berlin (Germany)

    2013-02-15

    Florbetaben is a {beta}-amyloid-targeted PET tracer with significant potential for augmenting the toolbox in the clinical diagnosis of Alzheimer's disease (AD). In dementia imaging, shortening of scan duration may simplify future clinical use. The aim of this retrospective study was to investigate the effect of scan duration on diagnostic accuracy. PET scans obtained from 25 AD patients and 25 healthy volunteers (HVs) were analysed. In each subject, scans of three different durations (5, 10 and 20 min; all starting 90 min after injection) were obtained, randomized, and visually assessed by three experts blinded to the subject's identity and group affiliation. Presence/absence of {beta}-amyloid and diagnostic confidence (0-100 %) were scored, and 10 % of the scans were re-read. Further, randomly selected datasets of ten AD patients and ten HVs were quantified using an established VOI-based approach and using a voxel-based approach. The sensitivity and specificity of the blinded read were 80 % and 96 %, respectively, for all scan durations. Diagnostic confidence was high (97 {+-} 6 %, 97 {+-} 6 % and 95 {+-} 8 % for the 20-min, 10-min and 5-min scans, respectively; n.s.), as was interreader agreement (kappa{sub 20} {sub min} = 0.94, kappa{sub 10} {sub min} = 0.94, kappa{sub 5} {sub min} = 0.89; n.s.). Intrareader agreement was highest for the 20-min scan (kappa = 1.00) and lower for the 10-min scan (kappa = 0.71) and 5-min scan (kappa = 0.80; p = 0.002 and 0.003 vs. the 20-min scan). For all scan durations, composite SUVRs (Cohen's d effect size 4.5, 3.9 and 4.8 for the 5-min, 10-min and 20-min scans; p < 0.0001 each) and individual brain volumes affected by {beta}-amyloid (Cohen's d effect size 1.6, 1.8 and 2.0 for the 5-min, 10-min and 20-min scans; p < 0.005 each) were significantly higher in AD patients than in HVs. Reduction in scan duration did not relevantly affect the accuracy of florbetaben PET scans in discriminating between AD patients

  3. Individualized quantification of brain {beta}-amyloid burden: results of a proof of mechanism phase 0 florbetaben PET trial in patients with Alzheimer's disease and healthy controls

    Energy Technology Data Exchange (ETDEWEB)

    Barthel, Henryk; Luthardt, Julia; Becker, Georg; Patt, Marianne; Sattler, Bernhard; Schildan, Andreas; Hesse, Swen; Meyer, Philipp M.; Sabri, Osama [University of Leipzig, Department of Nuclear Medicine, Leipzig (Germany); Hammerstein, Eva; Hartwig, Kristin; Gertz, Hermann-Josef [University of Leipzig, Department of Psychiatry, Leipzig (Germany); Eggers, Birk [Arzneimittelforschung Leipzig GmbH, Leipzig (Germany); Wolf, Henrike [University of Leipzig, Department of Psychiatry, Leipzig (Germany); University of Zurich, Department of Psychiatry, Zurich (Switzerland); Zimmermann, Torsten; Reischl, Joachim; Rohde, Beate; Reininger, Cornelia [Bayer Healthcare, Berlin (Germany)

    2011-09-15

    Complementing clinical findings with those generated by biomarkers - such as {beta}-amyloid-targeted positron emission tomography (PET) imaging - has been proposed as a means of increasing overall accuracy in the diagnosis of Alzheimer's disease (AD). Florbetaben ([{sup 18}F]BAY 94-9172) is a novel {beta}-amyloid PET tracer currently in global clinical development. We present the results of a proof of mechanism study in which the diagnostic efficacy, pharmacokinetics, safety and tolerability of florbetaben were assessed. The value of various quantitative parameters derived from the PET scans as potential surrogate markers of cognitive decline was also investigated. Ten patients with mild-moderate probable AD (DSM-IV and NINCDS-ADRDA criteria) and ten age-matched ({>=} 55 years) healthy controls (HCs) were administered a single dose of 300 MBq florbetaben, which contained a tracer mass dose of < 5 {mu}g. The 70-90 min post-injection brain PET data were visually analysed by three blinded experts. Quantitative assessment was also performed via MRI-based, anatomical sampling of predefined volumes of interest (VOI) and subsequent calculation of standardized uptake value (SUV) ratios (SUVRs, cerebellar cortex as reference region). Furthermore, single-case, voxelwise analysis was used to calculate individual ''whole brain {beta}-amyloid load''. Visual analysis of the PET data revealed nine of the ten AD, but only one of the ten HC brains to be {beta}-amyloid positive (p = 0.001), with high inter-reader agreement (weighted kappa {>=} 0.88). When compared to HCs, the neocortical SUVRs were significantly higher in the ADs (with descending order of effect size) in frontal cortex, lateral temporal cortex, occipital cortex, anterior and posterior cingulate cortices, and parietal cortex (p = 0.003-0.010). Voxel-based group comparison confirmed these differences. Amongst the PET-derived parameters, the Statistical Parametric Mapping-based whole brain

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    Fustiñana, Maria Sol; Ariel, Pablo; Federman, Noel; Freudenthal, Ramiro; Romano, Arturo

    2010-09-01

    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. 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 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.

  6. Protective effect of Nelumbo nucifera extracts on beta amyloid protein induced apoptosis in PC12 cells, in vitro model of Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Alaganandam Kumaran

    2018-01-01

    Full Text Available Alzheimer's disease (AD is the most common cause of dementia in the elderly. β-Amyloid (Aβ has been proposed to play a role in the pathogenesis of AD. Deposits of insoluble Aβ are found in the brains of patients with AD and are one of the pathological hallmarks of the disease, but the underlying signaling pathways are poorly understood. In order to develop antidementia agents with potential therapeutic value, we examined the inhibitory effect of the Nelumbo nucifera seed embryo extracts on to the aggregated amyloid β peptide (agg Aβ1–40-induced damage of differentiated PC-12 cells (dPC-12, a well-known cell model for AD. In the present study, seed embryos of N. nucifera were extracted with 70% methanol in water and then separated into hexane, ethyl acetate, n-butanol, and water layers. Among them, only the n-butanol layer showed strong activity and was therefore subjected to separation on Sephadex LH-20 chromatography. Two fractions showing potent activity were found to significantly inhibit Aβ1–40 toxicity on dPC-12 cells in increasing order of concentration (10–50 μg/mL. Further purification and characterization of these active fractions identified them to be flavonoids such as rutin, orientin, isoorientin, isoquercetrin, and hyperoside. 2,2-Diphenyl-1-picrylhydrazyl hydrate scavenging activity of the extracts was also carried out to ascertain the possible mechanism of the activity.

  7. PET imaging of alpha(v)beta(3) integrin expression in tumours with Ga-68-labelled mono-, di- and tetrameric RGD peptides

    NARCIS (Netherlands)

    Dijkgraaf, Ingrid; Yim, Cheng-Bin; Franssen, Gerben M.; Schuit, Robert C.; Luurtsema, Gert; Liu, Shuang; Oyen, Wim J. G.; Boerman, Otto C.

    Due to the restricted expression of alpha(v)beta(3) in tumours, alpha(v)beta(3) is considered a suitable receptor for tumour targeting. In this study the alpha(v)beta(3)-binding characteristics of Ga-68-labelled monomeric, dimeric and tetrameric RGD peptides were determined and compared with their

  8. Intrinsic folding of small peptide chains: spectroscopic evidence for the formation of beta-turns in the gas phase.

    Science.gov (United States)

    Chin, Wutharath; Dognon, Jean-Pierre; Piuzzi, François; Tardivel, Benjamin; Dimicoli, Iliana; Mons, Michel

    2005-01-19

    Laser desorption of model peptides coupled to laser spectroscopic techniques enables the gas-phase observation of genuine secondary structures of biology. Spectroscopic evidence for the formation of beta-turns in gas-phase peptide chains containing glycine and phenylalanine residues establishes the intrinsic stability of these forms and their ability to compete with other stable structures. The precise characterization of local minima on the potential energy surface from IR spectroscopy constitutes an acute assessment for the state-of-the-art quantum mechanical calculations also presented. The observation of different types of beta-turns depending upon the residue order within the sequence is found to be consistent with the residue propensities in beta-turns of proteins, which suggests that the prevalence of glycine in type II and II' turns stems essentially from an energetic origin, already at play under isolated conditions.

  9. Green-fluorescent protein+ Astrocytes Attach to beta-Amyloid Plaques in an Alzheimer Mouse Model and GFPare Sensitive for Clasmatodendrosis

    Directory of Open Access Journals (Sweden)

    Christian eHumpel

    2016-04-01

    Full Text Available Alzheimer’s disease (AD is pathologically characterized by beta-amyloid (Aβ plaques and Tau pathology. It is well-established that Aβ plaques are surrounded by reactive astrocytes, highly expressing glial fibrillary acidic protein (GFAP. In order to study the cellular interaction of reactive astrocytes with Aβ plaques, we crossbred mice overexpressing amyloid precursor protein (APP with the Swedish-Dutch-Iowa mutations (APP-SweDI with mice expressing green fluorescent protein (GFP under the GFAP-promotor. Three-dimensional confocal microscopy revealed a tight association and intense sprouting of astrocytic fine branched processes towards Aβ plaques in 12 month old mice. In order to study phagocytosis, 110 µm thick brain slices from 12 month old crossbred mice were cultured overnight, however, we found that the GFP fluorescence faded away, distal processes degenerated and a complete loss of astrocytic morphology was seen (clasmatodendrosis. In summary, our data show that GFP+ reactive astrocytes make intense contact with Aβ plaques but these cells are highly vulnerable for degeneration.

  10. Poor Memory Performance in Aged Cynomolgus Monkeys with Hippocampal Atrophy, Depletion of Amyloid Beta 1-42 and Accumulation of Tau Proteins in Cerebrospinal Fluid

    DEFF Research Database (Denmark)

    Darusman, Huda S; Pandelaki, Jacub; Mulyadi, Rahmad

    2014-01-01

    , aged cynomolgus monkeys were divided into two groups to compare high-performing (n=6) and low-performing (n=6) subjects. Both groups were tested for biomarkers related to Alzheimer's disease and their brains were scanned using structural magnetic resonance imaging. RESULTS: The subjects with poor DRT......BACKGROUND: Due to their similarities in behavior and disease pathology to humans, non-human primate models are desirable to complement small animals as models for the study of age-related dementia. MATERIALS AND METHODS: Based on their performance on delayed response task (DRT) tests of memory...... performance had evidence of atrophy in the hippocampus and cortical areas, significantly lower cerebrospinal fluid levels of amyloid beta amino acid 1-42 (pperforming well on the DRT tests. CONCLUSION: Old, memory...

  11. The soluble transcobalamin receptor (sCD320) is present in cerebrospinal fluid and correlates to dementia-related biomarkers tau proteins and amyloid-beta

    DEFF Research Database (Denmark)

    Abuyaman, Omar; Nexo, Ebba

    2015-01-01

    BACKGROUND: Cellular uptake of vitamin B12 (B12) demands binding of the vitamin to transcobalamin (TC) and recognition of TC-B12 (holoTC) by the receptor CD320. Recently, we identified a soluble form of CD320 (sCD320) in human plasma. Here we present data on the occurrence of this soluble receptor...... phospho-tau (181P) (p-tau), total tau (t-tau) and amyloid-beta 1-42 (Aβ) (n = 177) employing commercial ELISA kits (Innogenetics Company). Size exclusion chromatography was performed on a Superdex 200 column. RESULTS: The median sCD320 concentration in CSF (14 pmol/L) is around five times lower than...

  12. Near-infrared fluorescence molecular imaging of amyloid beta species and monitoring therapy in animal models of Alzheimer’s disease

    Science.gov (United States)

    Zhang, Xueli; Tian, Yanli; Zhang, Can; Tian, Xiaoyu; Ross, Alana W.; Moir, Robert D.; Sun, Hongbin; Tanzi, Rudolph E.; Moore, Anna; Ran, Chongzhao

    2015-01-01

    Near-infrared fluorescence (NIRF) molecular imaging has been widely applied to monitoring therapy of cancer and other diseases in preclinical studies; however, this technology has not been applied successfully to monitoring therapy for Alzheimer’s disease (AD). Although several NIRF probes for detecting amyloid beta (Aβ) species of AD have been reported, none of these probes has been used to monitor changes of Aβs during therapy. In this article, we demonstrated that CRANAD-3, a curcumin analog, is capable of detecting both soluble and insoluble Aβ species. In vivo imaging showed that the NIRF signal of CRANAD-3 from 4-mo-old transgenic AD (APP/PS1) mice was 2.29-fold higher than that from age-matched wild-type mice, indicating that CRANAD-3 is capable of detecting early molecular pathology. To verify the feasibility of CRANAD-3 for monitoring therapy, we first used the fast Aβ-lowering drug LY2811376, a well-characterized beta-amyloid cleaving enzyme-1 inhibitor, to treat APP/PS1 mice. Imaging data suggested that CRANAD-3 could monitor the decrease in Aβs after drug treatment. To validate the imaging capacity of CRANAD-3 further, we used it to monitor the therapeutic effect of CRANAD-17, a curcumin analog for inhibition of Aβ cross-linking. The imaging data indicated that the fluorescence signal in the CRANAD-17–treated group was significantly lower than that in the control group, and the result correlated with ELISA analysis of brain extraction and Aβ plaque counting. It was the first time, to our knowledge, that NIRF was used to monitor AD therapy, and we believe that our imaging technology has the potential to have a high impact on AD drug development. PMID:26199414

  13. Keampferol-3-O-rhamnoside abrogates amyloid beta toxicity by modulating monomers and remodeling oligomers and fibrils to non-toxic aggregates

    Directory of Open Access Journals (Sweden)

    Sharoar Md

    2012-12-01

    Full Text Available Abstract Background Aggregation of soluble, monomeric β- amyloid (Aβ to oligomeric and then insoluble fibrillar Aβ is a key pathogenic feature in development of Alzheimer’s disease (AD. Increasing evidence suggests that toxicity is linked to diffusible Aβ oligomers, rather than to insoluble fibrils. The use of naturally occurring small molecules for inhibition of Aβ aggregation has recently attracted significant interest for development of effective therapeutic strategies against the disease. A natural polyphenolic flavone, Kaempferol-3-O-rhamnoside (K-3-rh, was utilized to investigate its effects on aggregation and cytotoxic effects of Aβ42 peptide. Several biochemical techniques were used to determine the conformational changes and cytotoxic effect of the peptide in the presence and absence of K-3-rh. Results K-3-rh showed a dose-dependent effect against Aβ42 mediated cytotoxicity. Anti-amyloidogenic properties of K-3-rh were found to be efficient in inhibiting fibrilogenesis and secondary structural transformation of the peptide. The consequence of these inhibitions was the accumulation of oligomeric structural species. The accumulated aggregates were smaller, soluble, non-β-sheet and non-toxic aggregates, compared to preformed toxic Aβ oligomers. K-3-rh was also found to have the remodeling properties of preformed soluble oligomers and fibrils. Both of these conformers were found to remodel into non-toxic aggregates. The results showed that K-3-rh interacts with different Aβ conformers, which affects fibril formation, oligomeric maturation and fibrillar stabilization. Conclusion K-3-rh is an efficient molecule to hinder the self assembly and to abrogate the cytotoxic effects of Aβ42 peptide. Hence, K-3-rh and small molecules with similar structure might be considered for therapeutic development against AD.

  14. Effects of super-hard rice bread blended with black rice bran on amyloid β peptide production and abrupt increase in postprandial blood glucose levels in mice.

    Science.gov (United States)

    Nakamura, Sumiko; Hara, Takashi; Joh, Toshio; Kobayashi, Atsushi; Yamazaki, Akira; Kasuga, Kensaku; Ikeuchi, Takeshi; Ohtsubo, Ken'ichi

    2017-02-01

    Alzheimer's disease and type 2 diabetes are very serious diseases with the latter having been suggested to cause the former. We prepared super-hard rice bread blended with black rice bran (SRBBB), which contained a high amount of resistant starch that showed strong inhibitory activities against β-secretase and acetylcholinesterase even after heating. Black rice bran showed greater β-secretase inhibitory activity (3.6-fold) than Koshihikari rice. The bran contained more oleic acid and anthocyanin, meaning that it is potentially a biofunctional food with a high antioxidant capacity. Furthermore, aged mice, which were fed a SRBBB diet for four weeks, showed lower amyloid β 40 peptide in the blood than mice fed a commercial diet (p < 0.01). Additionally, their initial blood glucose levels (BGLs) after 12 weeks of being fed SRBBB were significantly lower than those in the control group. Taken together, our results indicate SRBBB shows promise for inhibiting not only amyloid β production, but also abrupt increases in postprandial BGLs.

  15. Biosynthesis and release of beta-endorphin-, N-acetyl beta-endorphin-, beta-endorphin-(1-27)-, and N-acetyl beta-endorphin-(1-27)-like peptides by rat pituitary neurointermediate lobe: beta-endorphin is not further processed by anterior lobe

    International Nuclear Information System (INIS)

    Liotta, A.S.; Yamaguchi, H.; Krieger, D.T.

    1981-01-01

    Continuous labeling and pulse-chase techniques were employed to study the synthesis and secretion of multiple forms of immunoreactive beta-endorphin by cultured dispersed rat anterior lobe cells and intact neurointermediate pituitary lobe. Intact neurointermediate lobes incorporated radiolabeled amino acids into four to six forms of immunoreactive beta-endorphin. Four of these forms were physicochemically similar to authentic beta-endorphin, N-acetylated beta-endorphin, beta-endorphin-(1-27), and N-acetylated beta-endorphin-(1-27). Pulse-chase studies indicated that a beta-lipotropin-like molecule served as a metabolic intermediate for a beta-endorphin-like molecule. As beta-endorphin-like material accumulated in the cell, some of it was N-acetylated (approximately 18% at 2 hr chase and approximately 65% at 18 hr chase). At later chase times, beta-endorphin-(1-27)- and N-acetylated beta-endorphin-(1-27)-like peptides were the predominant molecular species detected. All endorphin forms were detected in unlabeled tissue maintained in culture or tissue continuously labeled for 72 hr and were released into the medium under basal, stimulatory (10(-8) M norepinephrine), or inhibitory (10(-7) M dopamine) incubation conditions. In all cases, beta-endorphin-(1-27)-like species were the predominant forms (more than 70% of total) present in the cells and released into the medium. In contrast, approximately 90% of radiolabeled immunoreactive beta-endorphin extracted from anterior lobe cells and medium similarly incubated appeared to represent the authentic beta-endorphin molecule. Continuous labeling (72 hr) revealed the beta-lipotropin/beta-endorphin molar ratio to be approximately 4. We conclude that, in anterior lobe, most of the beta-endorphin is not processed further and is released intact, while in neurointermediate lobe, it serves as a biosynthetic intermediate

  16. Why are Functional Amyloids Non-Toxic in Humans?

    Directory of Open Access Journals (Sweden)

    Matthew P. Jackson

    2017-09-01

    Full Text Available Amyloids were first identified in association with amyloidoses, human diseases in which proteins and peptides misfold into amyloid fibrils. Subsequent studies have identified an array of functional amyloid fibrils that perform physiological roles in humans. Given the potential for the production of toxic species in amyloid assembly reactions, it is remarkable that cells can produce these functional amyloids without suffering any obvious ill effect. Although the precise mechanisms are unclear, there are a number of ways in which amyloid toxicity may be prevented. These include regulating the level of the amyloidogenic peptides and proteins, minimising the production of prefibrillar oligomers in amyloid assembly reactions, sequestrating amyloids within membrane bound organelles, controlling amyloid assembly by other molecules, and disassembling the fibrils under physiological conditions. Crucially, a better understanding of how toxicity is avoided in the production of functional amyloids may provide insights into the prevention of amyloid toxicity in amyloidoses.

  17. Stability of transmembrane amyloid β-peptide and membrane integrity tested by molecular modeling of site-specific Aβ42 mutations.

    Directory of Open Access Journals (Sweden)

    Chetan Poojari

    Full Text Available Interactions of the amyloid β-protein (Aβ with neuronal cell membranes, leading to the disruption of membrane integrity, are considered to play a key role in the development of Alzheimer's disease. Natural mutations in Aβ42, such as the Arctic mutation (E22G have been shown to increase Aβ42 aggregation and neurotoxicity, leading to the early-onset of Alzheimer's disease. A correlation between the propensity of Aβ42 to form protofibrils and its effect on neuronal dysfunction and degeneration has been established. Using rational mutagenesis of the Aβ42 peptide it was further revealed that the aggregation of different Aβ42 mutants in lipid membranes results in a variety of polymorphic aggregates in a mutation dependent manner. The mutant peptides also have a variable ability to disrupt bilayer integrity. To further test the connection between Aβ42 mutation and peptide-membrane interactions, we perform molecular dynamics simulations of membrane-inserted Aβ42 variants (wild-type and E22G, D23G, E22G/D23G, K16M/K28M and K16M/E22G/D23G/K28M mutants as β-sheet monomers and tetramers. The effects of charged residues on transmembrane Aβ42 stability and membrane integrity are analyzed at atomistic level. We observe an increased stability for the E22G Aβ42 peptide and a decreased stability for D23G compared to wild-type Aβ42, while D23G has the largest membrane-disruptive effect. These results support the experimental observation that the altered toxicity arising from mutations in Aβ is not only a result of the altered aggregation propensity, but also originates from modified Aβ interactions with neuronal membranes.

  18. Comparison and Analysis of 3,4 dihydrocylmandelic acid (DHMA) and noremetanephrine (NMN) on Amyloid-Beta 40 Monomer for treatment of Alzheimer's Disease using Molecular Dynamics Simulation

    Science.gov (United States)

    Choi, Woosung; Jee, Sang Eun; Jang, Seung Soon

    Alzheimer's disease (AD) is type of degenerative dementia caused memory loss and behavior problem. Main reason of AD is Amyloid-Beta 40(A β) mostly composed of α -helix form misfolds to insoluble fibrils and soluble oilgomer. This insoluble fibrils aggregate with beta sheet structure and form the plaque which is caused nurotoxicity in brain. Both 3,4 dihydrocylmandelic acid (DHMA) and noremetanephrine (NMN) are the metabolite of norepinephrine in brain . Also these are inhibit the changing formation of fibrils and maintain the α -helix structure. In this computational modeling study, both NMN and DHMA molecules were modified and analyzed for specific effect on the A β-monomer using molecular dynamics simulation. Using molecular dynamic simulation, NMN and DHMA act as modulator on three A β-monomer batches and could observe the conformational changing of these A β-monomer under the physiologocal condition. This computational experiment is designed to compare and analyze both of chemicals for determining which chamecal would be more effective on the conformation of A β 40 monomer.

  19. Conformational interconversions in peptide beta-turns: analysis of turns in proteins and computational estimates of barriers.

    Science.gov (United States)

    Gunasekaran, K; Gomathi, L; Ramakrishnan, C; Chandrasekhar, J; Balaram, P

    1998-12-18

    The two most important beta-turn features in peptides and proteins are the type I and type II turns, which differ mainly in the orientation of the central peptide unit. Facile conformational interconversion is possible, in principle, by a flip of the central peptide unit. Homologous crystal structures afford an opportunity to structurally characterize both possible conformational states, thus allowing identification of sites that are potentially stereochemically mobile. A representative data set of 250 high-resolution (turns that are assigned different conformational types (type I/type II) in related structures. A total of 55 examples of beta-turns were identified as possible candidates for a stereochemically mobile site. Of the 55 examples, 45 could be classified as a potential site for interconversion between type I and type II beta-turns, while ten correspond to flips from type I' to type II' structures. As a further check, the temperature factors of the central peptide unit carbonyl oxygen atom of the 55 examples were examined. The analysis reveals that the turn assignments are indeed reliable. Examination of the secondary structures at the flanking positions of the flippable beta-turns reveals that seven examples occur in the loop region of beta-hairpins, indicating that the formation of ordered secondary structures on either side of the beta-turn does not preclude local conformational variations. In these beta-turns, Pro (11 examples), Lys (nine examples) and Ser (seven examples) were most often found at the i+1 position. Glycine was found to occur overwhelmingly at position i+2 (28 examples), while Ser (seven examples) and Asn (six examples) were amongst the most frequent residues. Activation energy barriers for the interconversion between type I and type II beta-turns were computed using the peptide models Ac-Pro-Aib-NHMe and Ac-Pro-Gly-NHMe within the framework of the AM1 semi-empirical molecular orbital procedure. In order to have a uniform basis for

  20. Inhibiting and Remodeling Toxic Amyloid-Beta Oligomer Formation Using a Computationally Designed Drug Molecule That Targets Alzheimer's Disease

    Science.gov (United States)

    Downey, Matthew A.; Giammona, Maxwell J.; Lang, Christian A.; Buratto, Steven K.; Singh, Ambuj; Bowers, Michael T.

    2018-04-01

    Alzheimer's disease (AD) is rapidly reaching epidemic status among a burgeoning aging population. Much evidence suggests the toxicity of this amyloid disease is most influenced by the formation of soluble oligomeric forms of amyloid β-protein, particularly the 42-residue alloform (Aβ42). Developing potential therapeutics in a directed, streamlined approach to treating this disease is necessary. Here we utilize the joint pharmacophore space (JPS) model to design a new molecule [AC0107] incorporating structural characteristics of known Aβ inhibitors, blood-brain barrier permeability, and limited toxicity. To test the molecule's efficacy experimentally, we employed ion mobility mass spectrometry (IM-MS) to discover [AC0107] inhibits the formation of the toxic Aβ42 dodecamer at both high (1:10) and equimolar concentrations of inhibitor. Atomic force microscopy (AFM) experiments reveal that [AC0107] prevents further aggregation of Aβ42, destabilizes preformed fibrils, and reverses Aβ42 aggregation. This trend continues for long-term interaction times of 2 days until only small aggregates remain with virtually no fibrils or higher order oligomers surviving. Pairing JPS with IM-MS and AFM presents a powerful and effective first step for AD drug development.

  1. Synthesis and functional evaluation of a peptide derivative of 1-beta-D-arabinofuranosylcytosine.

    Science.gov (United States)

    Balajthy, Z; Aradi, J; Kiss, I T; Elödi, P

    1992-09-04

    We have synthesized a peptidyl prodrug derivative of 1-beta-D-arabinofuranosylcytosine (1) designed to be a selective substrate of plasmin. D-Val-Leu-Lys-ara-C (2) was obtained by coupling the protected peptide Cbz-D-Val-Leu-(N6-Cbz)Lys-OH and ara-C (1) by a water-soluble carbodiimide (EDCI), followed by the removal of the Cbz groups by using catalytic hydrogenolysis over Pd/C. The kinetic constant of hydrolysis of 2 in the presence of plasmin demonstrated effective release of 1. The amino group of 1, which is sensitive to the removal by cytidine deaminase, is protected in 2 by the formation of the amide bond resulting in a prolonged half-life of 2 in biological milieu. The antiproliferative efficiency of 2 against L1210 leukemic cells was significantly higher than that of 1. The activity of 2 was abolished in the presence of serine proteinase inhibitor, (4-amidinopheny)methanesulfonyl fluoride. These data indicate that 2 is a prodrug form of 1 in systems generating plasmin.

  2. Metabolic changes precede proteostatic dysfunction in a Drosophila model of Abeta peptide toxicity

    DEFF Research Database (Denmark)

    Ott, Stanislav; Vishnivetskaya, Anastasia; Malmendal, Anders

    2016-01-01

    Amyloid beta (Aβ) peptide aggregation is linked to the initiation of Alzheimer's disease; accordingly, aggregation-prone isoforms of Aβ, expressed in the brain, shorten the lifespan of Drosophila melanogaster. However, the lethal effects of Aβ are not apparent until after day 15. We used shibireT...

  3. The recombinant C-terminal fragment of tetanus toxin protects against cholinotoxicity by intraseptal injection of β-amyloid peptide (25-35) in rats.

    Science.gov (United States)

    Patricio-Martínez, A; Mendieta, L; Martínez, I; Aguilera, J; Limón, I D

    2016-02-19

    The recombinant C-terminal domain of tetanus toxin (Hc-TeTx) is a new non-toxic peptide of the tetanus toxin that exerts a protective action against glutamate excitotoxicity in motoneurons. Moreover, its efficacy as a neuroprotective agent has been demonstrated in several animal models of neurodegeneration. The eleven amino acids in the β amyloid peptide (Aβ25-35) mimic the toxic effects of the full β amyloid peptide (Aβ1-42), causing the impairment of the cholinergic system in the medial septum (MS) which, in turn, alters the septo-hippocampal pathway and leads to learning and memory impairments. The aim of this study was to examine the neuroprotective effects of the Hc-TeTx fragment against cholinotoxicity. The Hc-TeTx fragment (100 ng) was injected into the rats intercranially, with the Aβ(25-35) (2 μg) then injected into their MS. The animals were tested for spatial learning and memory in the eight-arm radial maze. The brains were removed to assess cholinergic markers, such as choline acetyltransferase (ChAT) and acetylcholinesterase (AChE), and to explore neurodegeneration in the MS and hippocampus, using amino-cupric silver and H&E staining. Finally, capase-3, a marker of apoptosis, was examined in the MS. Our results clearly demonstrate that the application of Hc-TeTx prevents the loss of cholinergic markers (ChAT and AChE), the activation of capase-3, and neurodegeneration in the MS and the CA1 and CA3 subfields of the hippocampus. All these improvements were reflected in spatial learning and memory performance, and were significantly higher compared with animals treated with Aβ(25-35). Interestingly, the single administration of Hc-TeTx into the MS modified the ChAT and AChE expression that affect cognitive processes, without inducing neurodegeneration or an increase in capase-3 expression in the MS and hippocampus. In summary, our findings suggest that the recombinant Hc-TeTx fragment offers effective protection for the septo-hippocampal pathway

  4. 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR attenuates the expression of LPS- and Aβ peptide-induced inflammatory mediators in astroglia

    Directory of Open Access Journals (Sweden)

    Giri Shailendra

    2005-09-01

    Full Text Available Abstract Background Alzheimer's disease (AD pathology shows characteristic 'plaques' rich in amyloid beta (Aβ peptide deposits. Inflammatory process-related proteins such as pro-inflammatory cytokines have been detected in AD brain suggesting that an inflammatory immune reaction also plays a role in the pathogenesis of AD. Glial cells in culture respond to LPS and Aβ stimuli by upregulating the expression of cytokines TNF-α, IL-1β, and IL-6, and also the expression of proinflammatory genes iNOS and COX-2. We have earlier reported that LPS/Aβ stimulation-induced ceramide and ROS generation leads to iNOS expression and nitric oxide production in glial cells. The present study was undertaken to investigate the neuroprotective function of AICAR (a potent activator of AMP-activated protein kinase in blocking the pro-oxidant/proinflammatory responses induced in primary glial cultures treated with LPS and Aβ peptide. Methods To test the anti-inflammatory/anti-oxidant functions of AICAR, we tested its inhibitory potential in blocking the expression of pro-inflammatory cytokines and iNOS, expression of COX-2, generation of ROS, and associated signaling following treatment of glial cells with LPS and Aβ peptide. We also investigated the neuroprotective effects of AICAR against the effects of cytokines and inflammatory mediators (released by the glia, in blocking neurite outgrowth inhibition, and in nerve growth factor-(NGF induced neurite extension by PC-12 cells. Results AICAR blocked LPS/Aβ-induced inflammatory processes by blocking the expression of proinflammatory cytokine, iNOS, COX-2 and MnSOD genes, and by inhibition of ROS generation and depletion of glutathione in astroglial cells. AICAR also inhibited down-stream signaling leading to the regulation of transcriptional factors such as NFκB and C/EBP which are critical for the expression of iNOS, COX-2, MnSOD and cytokines (TNF-α/IL-1β and IL-6. AICAR promoted NGF-induced neurite growth

  5. Improved targeting of the alpha(v)beta (3) integrin by multimerisation of RGD peptides.

    NARCIS (Netherlands)

    Dijkgraaf, I.; Kruijtzer, J.A.; Liu, S.; Soede, A.C.; Oyen, W.J.G.; Corstens, F.H.M.; Liskamp, R.M.; Boerman, O.C.

    2007-01-01

    PURPOSE: The integrin alpha(v)beta(3) is expressed on sprouting endothelial cells and on various tumour cell types. Due to the restricted expression of alpha(v)beta(3) in tumours, alpha(v)beta(3) is considered a suitable receptor for tumour targeting. In this study the alpha(v)beta(3) binding

  6. GM1 Ganglioside Inhibits β-Amyloid Oligomerization Induced by Sphingomyelin

    Czech Academy of Sciences Publication Activity Database

    Amaro, Mariana; Šachl, Radek; Aydogan, Gokcan; Mikhalyov, I.; Vácha, R.; Hof, Martin

    2016-01-01

    Roč. 55, č. 32 (2016), s. 9411-9415 ISSN 1433-7851 R&D Projects: GA ČR(CZ) GBP208/12/G016 Grant - others:GA MŠk(CZ) LM2010005 Institutional support: RVO:61388955 Keywords : amyloid beta-peptides * Alzheimer's disease * diffusion coefficients Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 11.994, year: 2016

  7. Curcumin Improves Amyloid β-Peptide (1-42 Induced Spatial Memory Deficits through BDNF-ERK Signaling Pathway.

    Directory of Open Access Journals (Sweden)

    Lu Zhang

    Full Text Available Curcumin, the most active component of turmeric, has various beneficial properties, such as antioxidant, anti-inflammatory, and antitumor effects. Previous studies have suggested that curcumin reduces the levels of amyloid and oxidized proteins and prevents memory deficits and thus is beneficial to patients with Alzheimer's disease (AD. However, the molecular mechanisms underlying curcumin's effect on cognitive functions are not well-understood. In the present study, we examined the working memory and spatial reference memory in rats that received a ventricular injection of amyloid-β1-42 (Aβ1-42, representing a rodent model of Alzheimer's disease (AD. The rats treated with Aβ1-42 exhibited obvious cognitive deficits in behavioral tasks. Chronic (seven consecutive days, once per day but not acute (once a day curcumin treatments (50, 100, and 200 mg/kg improved the cognitive functions in a dose-dependent manner. In addition, the beneficial effect of curcumin is accompanied by increased BDNF levels and elevated levels of phosphorylated ERK in the hippocampus. Furthermore, the cognition enhancement effect of curcumin could be mimicked by the overexpression of BDNF in the hippocampus and blocked by either bilateral hippocampal injections with lentiviruses that express BDNF shRNA or a microinjection of ERK inhibitor. These findings suggest that chronic curcumin ameliorates AD-related cognitive deficits and that upregulated BDNF-ERK signaling in the hippocampus may underlie the cognitive improvement produced by curcumin.

  8. Real-time amyloid aggregation monitoring with a photonic crystal-based approach.

    Science.gov (United States)

    Santi, Sara; Musi, Valeria; Descrovi, Emiliano; Paeder, Vincent; Di Francesco, Joab; Hvozdara, Lubos; van der Wal, Peter; Lashuel, Hilal A; Pastore, Annalisa; Neier, Reinhard; Herzig, Hans Peter

    2013-10-21

    We propose the application of a new label-free optical technique based on photonic nanostructures to real-time monitor the amyloid-beta 1-42 (Aβ(1-42)) fibrillization, including the early stages of the aggregation process, which are related to the onset of the Alzheimer's Disease (AD). The aggregation of Aβ peptides into amyloid fibrils has commonly been associated with neuronal death, which culminates in the clinical features of the incurable degenerative AD. Recent studies revealed that cell toxicity is determined by the formation of soluble oligomeric forms of Aβ peptides in the early stages of aggregation. At this phase, classical amyloid detection techniques lack in sensitivity. Upon a chemical passivation of the sensing surface by means of polyethylene glycol, the proposed approach allows an accurate, real-time monitoring of the refractive index variation of the solution, wherein Aβ(1-42) peptides are aggregating. This measurement is directly related to the aggregation state of the peptide throughout oligomerization and subsequent fibrillization. Our findings open new perspectives in the understanding of the dynamics of amyloid formation, and validate this approach as a new and powerful method to screen aggregation at early stages. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. How can a beta-sheet peptide be both a potent antimicrobial and harmfully toxic? Molecular dynamics simulations of protegrin-1 in micelles

    DEFF Research Database (Denmark)

    Langham, Allison A; Khandelia, Himanshu; Kaznessis, Yiannis N

    2006-01-01

    In this work, the naturally occurring beta-hairpin antimicrobial peptide protegrin-1 (PG-1) is studied by molecular dynamics simulation in all-atom sodium dodecylsulfate and dodecylphosphocholine micelles. These simulations provide a high-resolution picture of the interactions between the peptide...

  10. Imaging characteristic of dual-phase 18F-florbetapir (AV-45/Amyvid) PET for the concomitant detection of perfusion deficits and beta-amyloid deposition in Alzheimer's disease and mild cognitive impairment

    International Nuclear Information System (INIS)

    Lin, Kun-Ju; Hsiao, Ing-Tsung; Hsieh, Chia-Ju; Wey, Shiaw-Pyng; Yen, Tzu-Chen; Hsu, Jung-Lung; Huang, Chin-Chang; Huang, Kuo-Lun

    2016-01-01

    We investigated dual-phase 18 F-florbetapir (AV-45/Amyvid) PET imaging for the concomitant detection of brain perfusion deficits and beta-amyloid deposition in patients with Alzheimer's disease (AD) and amnestic mild cognitive impairment (MCI), and in cognitively healthy controls (HCs). A total of 82 subjects (24 AD patients, 44 MCI patients and 14 HCs) underwent both dual-phase 18 F-AV-45 PET and MRI imaging. Dual-phase dynamic PET imaging consisted of (1) five 1-min scans obtained 1 - 6 min after tracer injection (perfusion 18 F-AV-45 imaging, pAV-45), and (2) ten 1-min scans obtained 50 - 60 min after tracer injection (amyloid 18 F-AV-45 imaging). Amyloid-negative MCI/AD patients were excluded. Volume of interest analysis and statistical parametric mapping of pAV-45 and 18 F-AV-45 images were performed to investigate the perfusion deficits and the beta-amyloid burden in the three study groups. The associations between Mini-Mental State Examination (MMSE) scores and global perfusion deficits and amyloid deposition were investigated with linear and segmental linear correlation analyses. HCs generally had normal pAV-45 findings, whereas perfusion deficits were evident in the hippocampus, and temporal, parietal and middle frontal cortices in both MCI and AD patients. The motor-sensory cortex was relatively preserved. MMSE scores in the entire study cohort were significantly associated with the degree of perfusion impairment as assessed by pAV-45 imaging (r = 0.5156, P < 0.0001). 18 F-AV-45 uptake was significantly higher in AD patients than in the two other study groups. However, the correlation between MMSE scores and 18 F-AV-45 uptake in MCI patients was more of a binary phenomenon and began in MCI patients with MMSE score 23.14 when 18 F-AV-45 uptake was higher and MMSE score lower than in patients with early MCI. Amyloid deposition started in the