101
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Li H, Du Z, Lopes DHJ, Fradinger EA, Wang C, Bitan G. C-terminal tetrapeptides inhibit Aβ42-induced neurotoxicity primarily through specific interaction at the N-terminus of Aβ42. J Med Chem 2011; 54:8451-60. [PMID: 22087474 DOI: 10.1021/jm200982p] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Inhibition of amyloid β-protein (Aβ)-induced toxicity is a promising therapeutic strategy for Alzheimer's disease (AD). Previously, we reported that the C-terminal tetrapeptide Aβ(39-42) is a potent inhibitor of neurotoxicity caused by Aβ42, the form of Aβ most closely associated with AD. Here, initial structure-activity relationship studies identified key structural requirements, including chirality, side-chain structure, and a free N-terminus, which control Aβ(39-42) inhibitory activity. To elucidate the binding site(s) of Aβ(39-42) on Aβ42, we used intrinsic tyrosine (Y) fluorescence and solution-state NMR. The data suggest that Aβ(39-42) binds at several sites, of which the predominant one is located in the N-terminus of Aβ42, in agreement with recent modeling predictions. Thus, despite the small size of Aβ(39-42) and the hydrophobic, aliphatic nature of all four side-chains, the interaction of Aβ(39-42) with Aβ42 is controlled by specific intermolecular contacts requiring a combination of hydrophobic and electrostatic interactions and a particular stereochemistry.
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Affiliation(s)
- Huiyuan Li
- Department of Neurology, David Geffen School of Medicine, Brain Research Institute, University of California, Los Angeles, 635 Charles E. Young Drive South, Los Angeles, California 90095-7334, United States
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102
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A peptide that binds specifically to the β-amyloid of Alzheimer's disease: selection and assessment of anti-β-amyloid neurotoxic effects. PLoS One 2011; 6:e27649. [PMID: 22102917 PMCID: PMC3213187 DOI: 10.1371/journal.pone.0027649] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 10/21/2011] [Indexed: 11/24/2022] Open
Abstract
The accumulation of the amyloid-β peptide (Aβ) into amyloid plaques, an essential event in Alzheimer's disease (AD) pathogenesis, has caused researchers to seek compounds that physiologically bind Aβ and modulate its aggregation and neurotoxicity. In order to develop new Aβ-specific peptides for AD, a randomized 12-mer peptide library with Aβ1-10 as the target was used to identify peptides in the present study. After three rounds of selection, specific phages were screened, and their binding affinities to Aβ1-10 were found to be highly specific. Finally, a special peptide was synthesized according to the sequences of the selected phages. In addition, the effects of the special peptide on Aβ aggregation and Aβ-mediated neurotoxicity in vitro and in vivo were assessed. The results show that the special peptide not only inhibited the aggregation of Aβ into plaques, but it also alleviated Aβ-induced PC12 cell viability and apoptosis at appropriate concentrations as assessed by the cell counting kit-8 assay and propidium iodide staining. Moreover, the special peptide exhibited a protective effect against Aβ-induced learning and memory deficits in rats, as determined by the Morris water maze task. In conclusion, we selected a peptide that specifically binds Aβ1-10 and can modulate Aβ aggregation and Aβ-induced neuronal damage. This opens up possibilities for the development of a novel therapeutic approach for the treatment of AD.
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103
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Raj H, Puthan Veetil V, Szymanski W, Dekker FJ, Quax WJ, Feringa BL, Janssen DB, Poelarends GJ. Characterization of a thermostable methylaspartate ammonia lyase from Carboxydothermus hydrogenoformans. Appl Microbiol Biotechnol 2011; 94:385-97. [PMID: 22005738 PMCID: PMC3310078 DOI: 10.1007/s00253-011-3615-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 08/30/2011] [Accepted: 09/28/2011] [Indexed: 01/05/2023]
Abstract
Methylaspartate ammonia lyase (MAL; EC 4.3.1.2) catalyzes the reversible addition of ammonia to mesaconate to give (2S,3S)-3-methylaspartate and (2S,3R)-3-methylaspartate as products. MAL is of considerable biocatalytic interest because of its potential use for the asymmetric synthesis of substituted aspartic acids, which are important building blocks for synthetic enzymes, peptides, chemicals, and pharmaceuticals. Here, we have cloned the gene encoding MAL from the thermophilic bacterium Carboxydothermus hydrogenoformans Z-2901. The enzyme (named Ch-MAL) was overproduced in Escherichia coli and purified to homogeneity by immobilized metal affinity chromatography. Ch-MAL is a dimer in solution, consisting of two identical subunits (∼49 kDa each), and requires Mg2+ and K+ ions for maximum activity. The optimum pH and temperature for the deamination of (2S,3S)-3-methylaspartic acid are 9.0 and 70°C (kcat = 78 s−1 and Km = 16 mM). Heat inactivation assays showed that Ch-MAL is stable at 50°C for >4 h, which is the highest thermal stability observed among known MALs. Ch-MAL accepts fumarate, mesaconate, ethylfumarate, and propylfumarate as substrates in the ammonia addition reaction. The enzyme also processes methylamine, ethylamine, hydrazine, hydroxylamine, and methoxylamine as nucleophiles that can replace ammonia in the addition to mesaconate, resulting in the corresponding N-substituted methylaspartic acids with excellent diastereomeric excess (>98% de). This newly identified thermostable MAL appears to be a potentially attractive biocatalyst for the stereoselective synthesis of aspartic acid derivatives on large (industrial) scale.
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Affiliation(s)
- Hans Raj
- Department of Pharmaceutical Biology, University of Groningen, Antonius Deusinglaan 1, Groningen, The Netherlands
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104
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Design and development of peptides and peptide mimetics as antagonists for therapeutic intervention. Future Med Chem 2011; 2:1813-22. [PMID: 21428804 DOI: 10.4155/fmc.10.259] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The concept of peptides as therapeutic agents has been historically disregarded by the pharmaceutical industry on account of their susceptibility to degradation, their size and consequent limitations in methods of delivery. Recently, however, there has been a surge of interest in peptides and their mimetics as potential antagonists for therapeutic intervention. This is in part due to the increased half-life and oral availability that has been achieved for a number of peptide-based systems, the introduction and acceptance of alternative delivery methods, and the prevalence of proteomics to identify countless protein-protein interaction targets. The use of peptides and molecules that mimic their function therefore has great potential to effectively target a range of proteins that are pathogenically implicated in numerous diseases.
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105
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Viet MH, Ngo ST, Lam NS, Li MS. Inhibition of Aggregation of Amyloid Peptides by Beta-Sheet Breaker Peptides and Their Binding Affinity. J Phys Chem B 2011; 115:7433-46. [DOI: 10.1021/jp1116728] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Man Hoang Viet
- Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw, Poland
| | - Son Tung Ngo
- Institute for Computational Science and Technology, 6 Quarter, Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Vietnam
| | - Nguyen Sy Lam
- Computational Physics Laboratory, Vietnam National University, Ho Chi Minh City, 227 Nguyen Van Cu, District 5, Vietnam
| | - Mai Suan Li
- Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw, Poland
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106
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Hochdörffer K, März-Berberich J, Nagel-Steger L, Epple M, Meyer-Zaika W, Horn AHC, Sticht H, Sinha S, Bitan G, Schrader T. Rational design of β-sheet ligands against Aβ42-induced toxicity. J Am Chem Soc 2011; 133:4348-58. [PMID: 21381732 DOI: 10.1021/ja107675n] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A β-sheet-binding scaffold was equipped with long-range chemical groups for tertiary contacts toward specific regions of the Alzheimer's Aβ fibril. The new constructs contain a trimeric aminopyrazole carboxylic acid, elongated with a C-terminal binding site, whose influence on the aggregation behavior of the Aβ(42) peptide was studied. MD simulations after trimer docking to the anchor point (F19/F20) suggest distinct groups of complex structures each of which featured additional specific interactions with characteristic Aβ regions. Members of each group also displayed a characteristic pattern in their antiaggregational behavior toward Aβ. Specifically, remote lipophilic moieties such as a dodecyl, cyclohexyl, or LPFFD fragment can form dispersive interactions with the nonpolar cluster of amino acids between I31 and V36. They were shown to strongly reduce Thioflavine T (ThT) fluorescence and protect cells from Aβ lesions (MTT viability assays). Surprisingly, very thick fibrils and a high β-sheet content were detected in transmission electron microscopy (TEM) and CD spectroscopic experiments. On the other hand, distant single or multiple lysines which interact with the ladder of stacked E22 residues found in Aβ fibrils completely dissolve existing β-sheets (ThT, CD) and lead to unstructured, nontoxic material (TEM, MTT). Finally, the triethyleneglycol spacer between heterocyclic β-sheet ligand and appendix was found to play an active role in destabilizing the turn of the U-shaped protofilament. Fluorescence correlation spectroscopy (FCS) and sedimentation velocity analysis (SVA) provided experimental evidence for some smaller benign aggregates of very thin, delicate structure (TEM, MTT). A detailed investigation by dynamic light scattering (DLS) and other methods proved that none of the new ligands acts as a colloid. The evolving picture for the disaggregation mechanism by these new hybrid ligands implies transformation of well-ordered fibrils into less structured aggregates with a high molecular weight. In the few cases where fibrillar components remain, these display a significantly altered morphology and have lost their acute cellular toxicity.
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Affiliation(s)
- Katrin Hochdörffer
- Universität Duisburg-Essen, Fachbereich Chemie, Universitätstrasse 5, 45117 Essen, Germany
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107
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Yu X, Wang Q, Zheng J. Structural determination of Abeta25-35 micelles by molecular dynamics simulations. Biophys J 2010; 99:666-74. [PMID: 20643087 DOI: 10.1016/j.bpj.2010.05.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 04/29/2010] [Accepted: 05/03/2010] [Indexed: 10/19/2022] Open
Abstract
Amyloid-beta (Abeta) peptides and other amyloidogenic proteins can form a wide range of soluble oligomers of varied morphologies at the early aggregation stage, and some of these oligomers are biologically relevant to the pathogenesis of Alzheimer's disease. Spherical micelle-like oligomers have been often observed for many different types of amyloids. Here, we report a hybrid computational approach to systematically construct, search, optimize, and rank soluble micelle-like Abeta25-35 structures with different side-chain packings at the atomic level. Simulations reveal for the first time, to our knowledge, that two Abeta micelles with antiparallel peptide organization and distinct surface hydrophobicity display high structural stability. Stable micelles experience a slow secondary structural transition from turn to alpha-helix. Energetic analysis coupled with computational mutagenesis reveals that van der Waals and solvation energies play a more pronounced role in stabilizing the micelles, whereas the electrostatic energies present a stable but minor energetic contribution to peptide assemblies. Modeled Abeta micelles with shapes and dimensions similar to those of experimentally derived spherical structures also provide detailed information about the roles of structural dynamics and transition in the formation of amyloid fibrils. The strong binding affinity of our micelles to antibodies implies that micelles may be a biologically relevant species.
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Affiliation(s)
- Xiang Yu
- Department of Chemical and Biomolecular Engineering, University of Akron, Akron, Ohio, USA
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108
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Lanning JD, Hawk AJ, Derryberry J, Meredith SC. Chaperone-like N-methyl peptide inhibitors of polyglutamine aggregation. Biochemistry 2010; 49:7108-18. [PMID: 20583779 DOI: 10.1021/bi1006095] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Polyglutamine expansion in the exon 1 domain of huntingtin leads to aggregation into beta-sheet-rich insoluble aggregates associated with Huntington's disease. We assessed eight polyglutamine peptides with different permutations of N-methylation of backbone and side chain amides as potential inhibitors of polyglutamine aggregation. Surprisingly, the most effective inhibitor, 5QMe(2) [Anth-K-Q-Q(Me(2))-Q-Q(Me(2))-Q-CONH(2), where Anth is N-methylanthranilic acid and Q(Me(2)) is side chain N-methyl Q], has only side chain methylations at alternate residues, highlighting the importance of side chain interactions in polyglutamine fibrillogenesis. Above a 1:1 stoichiometric ratio, 5QMe(2) can completely prevent fibrillation of a synthetic aggregating peptide, YAQ(12)A; it also shows significant inhibition at substoichiometric ratios. Surface plasmon resonance (SPR) measurements show a moderate K(d) with very fast k(on) and k(off) values. Sedimentation equilibrium analytical ultracentrifugation indicates that 5QMe(2) is predominantly or entirely monomeric at concentrations of <or=1 mM and that it forms a 1:1 stoichiometric complex with a fibril-forming target, YAQ(12)A. 5QMe(2) inhibits not only nucleation of YAQ(12)A but also fibril extension, as shown by the fact that it also inhibits seeded fibril growth where the nucleation steps are bypassed. 5QMe(2) acts on its targets only when they are in the PPII-like conformation, but not after they undergo a transition to beta-sheets. Thus, 5QMe(2) does not disassemble preformed YAQ(12)A; this contrasts with our previously described, backbone N-methylated inhibitors of beta-amyloid aggregation [Gordon, D. J., et al. (2001) Biochemistry 40, 8237-8245; Gordon, D. J., et al. (2002) J. Pept. Res. 60, 37-55]. The mode of action of 5QMe(2) is reminiscent of that of chaperones, because it binds and releases its targets very rapidly and maintains them in a nonaggregation-prone, monomeric state, in this case, the polyproline II (PPII)-like conformation, as shown by circular dichroism spectroscopy.
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Affiliation(s)
- Jennifer D Lanning
- Department of Pathology, The University of Chicago, Chicago, Illinois 60637, USA
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109
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Li H, Monien BH, Lomakin A, Zemel R, Fradinger EA, Tan M, Spring SM, Urbanc B, Xie CW, Benedek GB, Bitan G. Mechanistic investigation of the inhibition of Abeta42 assembly and neurotoxicity by Abeta42 C-terminal fragments. Biochemistry 2010; 49:6358-64. [PMID: 20568734 DOI: 10.1021/bi100773g] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Oligomeric forms of amyloid beta-protein (Abeta) are key neurotoxins in Alzheimer's disease (AD). Previously, we found that C-terminal fragments (CTFs) of Abeta42 interfered with assembly of full-length Abeta42 and inhibited Abeta42-induced toxicity. To decipher the mechanism(s) by which CTFs affect Abeta42 assembly and neurotoxicity, here, we investigated the interaction between Abeta42 and CTFs using photoinduced cross-linking and dynamic light scattering. The results demonstrate that distinct parameters control CTF inhibition of Abeta42 assembly and Abeta42-induced toxicity. Inhibition of Abeta42-induced toxicity was found to correlate with stabilization of oligomers with a hydrodynamic radius (R(H)) of 8-12 nm and attenuation of formation of oligomers with an R(H) of 20-60 nm. In contrast, inhibition of Abeta42 paranucleus formation correlated with CTF solubility and the degree to which CTFs formed amyloid fibrils themselves but did not correlate with inhibition of Abeta42-induced toxicity. Our findings provide important insight into the mechanisms by which different CTFs inhibit the toxic effect of Abeta42 and suggest that stabilization of nontoxic Abeta42 oligomers is a promising strategy for designing inhibitors of Abeta42 neurotoxicity.
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Affiliation(s)
- Huiyuan Li
- Department of Neurology, David Geffen School of Medicine, University of California-Los Angeles, 635 Charles E.Young Drive S., Los Angeles, CA 90095, USA
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110
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Extensive lysine methylation in hyperthermophilic crenarchaea: potential implications for protein stability and recombinant enzymes. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2010; 2010. [PMID: 20811616 PMCID: PMC2929605 DOI: 10.1155/2010/106341] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Accepted: 07/01/2010] [Indexed: 11/18/2022]
Abstract
In eukarya and bacteria, lysine methylation is relatively rare and is catalysed by sequence-specific lysine methyltransferases that typically have only a single-protein target. Using RNA polymerase purified from the thermophilic crenarchaeum Sulfolobus solfataricus, we identified 21 methyllysines distributed across 9 subunits of the enzyme. The modified lysines were predominantly in alpha-helices and showed no conserved sequence context. A limited survey of the Thermoproteus tenax proteome revealed widespread modification with 52 methyllysines in 30 different proteins. These observations suggest the presence of an unusual lysine methyltransferase with relaxed specificity in the crenarchaea. Since lysine methylation is known to enhance protein thermostability, this may be an adaptation to a thermophilic lifestyle. The implications of this modification for studies and applications of recombinant crenarchaeal enzymes are discussed.
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111
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In vitro ADMET and physicochemical investigations of poly-N-methylated peptides designed to inhibit Aβ aggregation. Bioorg Med Chem 2010; 18:5896-902. [DOI: 10.1016/j.bmc.2010.06.087] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 06/24/2010] [Accepted: 06/28/2010] [Indexed: 11/23/2022]
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112
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Tomlinson JH, Craven CJ, Williamson MP, Pandya MJ. Dimerization of protein G B1 domain at low pH: a conformational switch caused by loss of a single hydrogen bond. Proteins 2010; 78:1652-61. [PMID: 20112422 DOI: 10.1002/prot.22683] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A number of signals in the NMR spectrum of the B1 domain of staphylococcal protein G (GB1) show a chemical shift dependence on the concentration of the protein at pH 3 but not at neutral pH, implying the existence of self-association at low pH. NMR backbone relaxation experiments show that GB1 undergoes a slow conformational exchange at pH 3, which is not seen at higher pH. Analysis of relaxation dispersion experiments yields a self-association constant of 50 mM, and shows that (15)N chemical shift changes in the dimer interface are up to 3 ppm. The shift changes measured from concentration-dependent HSQC spectra and from relaxation dispersion show good consistency. Measurements of chemical shifts as a function of pH show that a hydrogen bond between the sidechains of Asp44 and Gln40 is broken when Asp44 is protonated, and that loss of this hydrogen bond leads to the breaking of the (i, i + 4) backbone helical hydrogen bond from Asp44 HN to Gln40 O, and therefore to a loss of two residues from the C-terminal end of the helix. This weakens the helix structure and facilitates the loss of further helical structure thus permitting dimerization, which is suggested to occur in the same way as observed for the A42F mutant of GB1 (Jee et al., Proteins 2007;71:1420-1431), by formation of an antiparallel beta-sheet between the edge strands 2 in two monomers. The monomer/dimer ratio is thus a finely balanced equilibrium even in the wild type protein.
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Affiliation(s)
- Jennifer H Tomlinson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
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113
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Cabaleiro-Lago C, Quinlan-Pluck F, Lynch I, Dawson KA, Linse S. Dual effect of amino modified polystyrene nanoparticles on amyloid β protein fibrillation. ACS Chem Neurosci 2010; 1:279-87. [PMID: 22778827 DOI: 10.1021/cn900027u] [Citation(s) in RCA: 213] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Accepted: 01/18/2010] [Indexed: 11/29/2022] Open
Abstract
The fibrillation kinetics of the amyloid β peptide is analyzed in presence of cationic polystyrene nanoparticles of different size. The results highlight the importance of the ratio between the peptide and particle concentration. Depending on the specific ratio, the kinetic effects vary from acceleration of the fibrillation process by reducing the lag phase at low particle surface area in solution to inhibition of the fibrillation process at high particle surface area. The kinetic behavior can be explained if we assume a balance between two different pathways: first fibrillation of free monomer in solution and second nucleation and fibrillation promoted at the particle surface. The overall rate of fibrillation will depend on the interplay between these two pathways, and the predominance of one mechanism over the other will be determined by the relative equilibrium and rate constants.
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Affiliation(s)
- Celia Cabaleiro-Lago
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Fiona Quinlan-Pluck
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Iseult Lynch
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Kenneth A. Dawson
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Sara Linse
- Biochemistry Department, Lund University, PO Box 124, 22100 Lund, Sweden
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114
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Tarawneh R, Galvin JE. Potential future neuroprotective therapies for neurodegenerative disorders and stroke. Clin Geriatr Med 2010; 26:125-47. [PMID: 20176298 PMCID: PMC2828394 DOI: 10.1016/j.cger.2009.12.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The cellular mechanisms underlying neuronal loss and neurodegeneration have been an area of interest in the last decade. Although neurodegenerative diseases such as Alzheimer disease, Parkinson disease, and Huntington disease each have distinct clinical symptoms and pathologies, they all share common mechanisms such as protein aggregation, oxidative injury, inflammation, apoptosis, and mitochondrial injury that contribute to neuronal loss. Although cerebrovascular disease has different causes from the neurodegenerative disorders, many of the same common disease mechanisms come into play following a stroke. Novel therapies that target each of these mechanisms may be effective in decreasing the risk of disease, abating symptoms, or slowing down their progression. Although most of these therapies are experimental, and require further investigation, a few seem to offer promise.
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Affiliation(s)
- Rawan Tarawneh
- Alzheimer Disease Research Center, Washington University School of Medicine, St Louis, MO, 63108
- Department of Neurology, Washington University School of Medicine, St Louis, MO, 63108
| | - James E. Galvin
- Alzheimer Disease Research Center, Washington University School of Medicine, St Louis, MO, 63108
- Department of Neurobiology, Washington University School of Medicine, St Louis, MO, 63108
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115
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Pratim Bose P, Chatterjee U, Nerelius C, Govender T, Norström T, Gogoll A, Sandegren A, Göthelid E, Johansson J, Arvidsson PI. Poly-N-methylated amyloid beta-peptide (Abeta) C-terminal fragments reduce Abeta toxicity in vitro and in Drosophila melanogaster. J Med Chem 2010; 52:8002-9. [PMID: 19908889 DOI: 10.1021/jm901092h] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Alzheimer's disease (AD), an age related neurodegenerative disorder, threatens to become a major health-economic problem. Assembly of 40- or 42-residue amyloid beta-peptides (Abeta) into neurotoxic oligo-/polymeric beta-sheet structures is an important pathogenic feature in AD, thus, inhibition of this process has been explored to prevent or treat AD. The C-terminal part plays an important role in Abeta aggregation, but most Abeta aggregation inhibitors have targeted the central region around residues 16-23. Herein, we synthesized hexapeptides with varying extents of N-methylation based on residues 32-37 of Abeta, to target its C-terminal region. We measured the peptides' abilities to retard beta-sheet and fibril formation of Abeta and to reduce Abeta neurotoxicity. A penta-N-methylated peptide was more efficient than peptides with 0, 2, or 3 N-methyl groups. This penta-N-methylated peptide moreover increased life span and locomotor activity in Drosophila melanogaster flies overexpressing human Abeta(1-42).
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Affiliation(s)
- Partha Pratim Bose
- Department of Biochemistry and Organic Chemistry, Uppsala University, Uppsala, Sweden
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116
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Abstract
The aggregation of numerous peptides or proteins has been linked to the onset of disease, including Abeta (amyloid beta-peptide) in AD (Alzheimer's disease), asyn (alpha-synuclein) in Parkinson's disease and amylin in Type 2 diabetes. Diverse amyloidogenic proteins can often be cut down to an SRE (self-recognition element) of as few as five residues that retains the ability to aggregate. SREs can be used as a starting point for aggregation inhibitors. In particular, N-methylated SREs can bind to a target on one side, but have hydrogen-bonding blocked on their methylated face, interfering with further assembly. We applied this strategy to develop Abeta toxicity inhibitors. Our compounds, and a range of compounds from the literature, were compared under the same conditions, using biophysical and toxicity assays. Two N-methylated D-peptide inhibitors with unnatural side chains were the most effective and can reverse Abeta-induced inhibition of LTP (long-term potentiation) at concentrations as low as 10 nM. An SRE in asyn (VAQKTV) was identified using solid-state NMR. When VAQKTV was N-methylated, it was able to disrupt asyn aggregation. N-methylated derivatives of the SRE of amylin are also able to inhibit amylin aggregation.
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117
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Kaminsky YG, Marlatt MW, Smith MA, Kosenko EA. Subcellular and metabolic examination of amyloid-beta peptides in Alzheimer disease pathogenesis: evidence for Abeta(25-35). Exp Neurol 2009; 221:26-37. [PMID: 19751725 DOI: 10.1016/j.expneurol.2009.09.005] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 09/03/2009] [Accepted: 09/04/2009] [Indexed: 11/28/2022]
Abstract
Amyloid-beta peptide (Abeta) is a central player in the pathogenesis and diagnosis of Alzheimer disease. It aggregates to form the core of Alzheimer disease-associated plaques found in coordination with tau deposits in diseased individuals. Despite this clinical relevance, no single hypothesis satisfies and explicates the role of Abeta in toxicity and progression of the disease. To explore this area, investigators have focused on mechanisms of cellular dysfunction, aggregation, and maladaptive responses. Extensive research has been conducted using various methodologies to investigate Abeta peptides and oligomers, and these multiple facets have provided a wealth of data from specific models. Notably, the utility of each experiment must be considered in regards to the brain environment. The use of Abeta(25-35) in studies of cellular dysfunction has provided data indicating that the peptide is indeed responsible for multiple disturbances to cellular integrity. We will review how Abeta peptide induces oxidative stress and calcium homeostasis, and how multiple enzymes are deleteriously impacted by Abeta(25-35). Understanding and discussing the origin and properties of Abeta peptides is essential to evaluating their effects on various intracellular metabolic processes. Attention will also be specifically directed to metabolic compartmentation in affected brain cells, including mitochondrial, cytosolic, nuclear, and lysosomal enzymes.
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Affiliation(s)
- Yury G Kaminsky
- Institute of Theoretical and Experimental Biophysics, RAS, Pushchino, Russia.
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118
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Dasilva KA, Shaw JE, McLaurin J. Amyloid-beta fibrillogenesis: structural insight and therapeutic intervention. Exp Neurol 2009; 223:311-21. [PMID: 19744483 DOI: 10.1016/j.expneurol.2009.08.032] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 08/12/2009] [Accepted: 08/27/2009] [Indexed: 02/02/2023]
Abstract
Structural insight into the conformational changes associated with aggregation and assembly of fibrils has provided a number of targets for therapeutic intervention. Solid-state NMR, hydrogen/deuterium exchange and mutagenesis strategies have been used to probe the secondary and tertiary structure of amyloid fibrils and key intermediates. Rational design of peptide inhibitors directed against key residues important for aggregation and stabilization of fibrils has demonstrated effectiveness at inhibiting fibrillogenesis. Studies on the interaction between Abeta and cell membranes led to the discovery that inositol, the head group of phosphatidylinositol, inhibits fibrillogenesis. As a result, scyllo-inositol is currently in clinical trials for the treatment of AD. Additional small-molecule inhibitors, including polyphenolic compounds such as curcumin, (-)-epigallocatechin gallate (EGCG), and grape seed extract have been shown to attenuate Abeta aggregation through distinct mechanisms, and have shown effectiveness at reducing amyloid levels when administered to transgenic mouse models of AD. Although the results of ongoing clinical trials remain to be seen, these compounds represent the first generation of amyloid-based therapeutics, with the potential to alter the progression of AD and, when used prophylactically, alleviate the deposition of Abeta.
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Affiliation(s)
- Kevin A Dasilva
- Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
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119
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Madine J, Wang X, Brown DR, Middleton DA. Evaluation of β-Alanine- and GABA-Substituted Peptides as Inhibitors of Disease-Linked Protein Aggregation. Chembiochem 2009; 10:1982-7. [DOI: 10.1002/cbic.200900219] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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120
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Kaminsky YG, Kosenko EA. Effects of amyloid-beta peptides on hydrogen peroxide-metabolizing enzymes in rat brainin vivo. Free Radic Res 2009; 42:564-73. [DOI: 10.1080/10715760802159057] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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121
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Chebaro Y, Derreumaux P. Targeting the early steps of Abeta16-22 protofibril disassembly by N-methylated inhibitors: a numerical study. Proteins 2009; 75:442-52. [PMID: 18837034 DOI: 10.1002/prot.22254] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Aggregation of the Abeta1-40/Abeta1-42 peptides is a key factor in Alzheimer's disease. Though the inhibitory effect of N-methylated Abeta16-22 (mAbeta16-22) peptides is well characterized in vitro, there is little information on how they disassemble full-length Abeta fibrils or block fibril formation. Here, we report coarse-grained implicit solvent molecular dynamics (MD) and replica exchange molecular dynamics (REMD) simulations on Abeta16-22 and mAbeta16-22 monomers, and then a preformed six-chain Abeta16-22 bilayer with either four copies of Abeta16-22 or four copies of mAbeta16-22. Our simulations show that the effect of N-methylation on mAbeta16-22 monomer is to reduce the density of compact forms. While 100 ns MD trajectories do not reveal any significant differences between the two ten-chain systems, the REMD simulations totaling 1 micros help understand the first steps of Abeta16-22 protofibril disassembly by N-methylated inhibitors. Notably, we find that mAbeta16-22 preferentially interacts with Abeta16-22 by blocking both beta-sheet extension and lateral association of layers, but also by intercalation of the inhibitors allowing sequestration of Abeta16-22 peptides. This third binding mode is particularly appealing for blocking Abeta fibrillogenesis.
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Affiliation(s)
- Yassmine Chebaro
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, Institut de Biologie, Physico Chimique et Université Paris 7 Denis Diderot, 13 rue Pierre et Marie Curie, Paris 75005, France
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122
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Hashimoto M, Shahdat HM, Katakura M, Tanabe Y, Gamoh S, Miwa K, Shimada T, Shido O. Effects of docosahexaenoic acid on in vitro amyloid beta peptide 25–35 fibrillation. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:289-96. [DOI: 10.1016/j.bbalip.2009.01.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 12/22/2008] [Accepted: 01/16/2009] [Indexed: 10/21/2022]
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123
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Hawkes CA, Ng V, McLaurin J. Small molecule inhibitors of Aβ-aggregation and neurotoxicity. Drug Dev Res 2009. [DOI: 10.1002/ddr.20290] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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124
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De Bona P, Laura Giuffrida M, Caraci F, Copani A, Pignataro B, Attanasio F, Cataldo S, Pappalardo G, Rizzarelli E. Design and synthesis of new trehalose-conjugated pentapeptides as inhibitors of Aβ(1-42) fibrillogenesis and toxicity. J Pept Sci 2009; 15:220-8. [DOI: 10.1002/psc.1109] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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125
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Affiliation(s)
- Seol-Heui Han
- Department of Neurology, Konkuk University School of Medicine Center for Geriatric Neuroscience Research, IBST, Konkuk University, Korea.
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126
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Soto C, Martin Z. Therapeutic strategies against protein misfolding in neurodegenerative diseases. Expert Opin Drug Discov 2008; 4:71-84. [DOI: 10.1517/13543770802630455] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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127
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Rivière C, Delaunay JC, Immel F, Cullin C, Monti JP. The polyphenol piceid destabilizes preformed amyloid fibrils and oligomers in vitro: hypothesis on possible molecular mechanisms. Neurochem Res 2008; 34:1120-8. [PMID: 19030989 DOI: 10.1007/s11064-008-9883-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2008] [Indexed: 11/30/2022]
Abstract
Alzheimer's disease (AD) is characterized by deposits of amyloid in various tissues. The neuronal cytotoxicity of Abeta peptides is attributed not only to various mechanisms but also to amyloid fibrils and soluble oligomeric intermediates. Consequently, finding molecules to prevent or reverse the oligomerization and fibrillization of Abeta could be of therapeutic value in the treatment of AD. We show that piceid, a polyphenol of the stilbene family, destabilized fibrils and oligomers to give back monomers that are not neurotoxic molecules. The mechanism of this destabilization could be a dynamic interaction between the polyphenol and the Abeta that could open the hydrophobic zipper and shift the reversible equilibrium "random coil<-->beta-sheet" to the disordered structure.
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Affiliation(s)
- Céline Rivière
- Laboratoire de physique et biophysique, GESVAB EA 3675, ISVV, Université de Bordeaux 2, Bordeaux cedex, France
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128
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Cabaleiro-Lago C, Quinlan-Pluck F, Lynch I, Lindman S, Minogue AM, Thulin E, Walsh DM, Dawson KA, Linse S. Inhibition of Amyloid β Protein Fibrillation by Polymeric Nanoparticles. J Am Chem Soc 2008; 130:15437-43. [DOI: 10.1021/ja8041806] [Citation(s) in RCA: 431] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Celia Cabaleiro-Lago
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland, Department of Biophysical Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, and Laboratory for Neurodegenerative Research, UCD Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Fiona Quinlan-Pluck
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland, Department of Biophysical Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, and Laboratory for Neurodegenerative Research, UCD Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Iseult Lynch
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland, Department of Biophysical Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, and Laboratory for Neurodegenerative Research, UCD Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Stina Lindman
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland, Department of Biophysical Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, and Laboratory for Neurodegenerative Research, UCD Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Aedin M. Minogue
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland, Department of Biophysical Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, and Laboratory for Neurodegenerative Research, UCD Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Eva Thulin
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland, Department of Biophysical Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, and Laboratory for Neurodegenerative Research, UCD Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Dominic M. Walsh
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland, Department of Biophysical Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, and Laboratory for Neurodegenerative Research, UCD Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Kenneth A. Dawson
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland, Department of Biophysical Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, and Laboratory for Neurodegenerative Research, UCD Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Sara Linse
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland, Department of Biophysical Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, and Laboratory for Neurodegenerative Research, UCD Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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129
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Suh EC, Jung YJ, Kim YA, Park EM, Lee KE. Aβ25–35 induces presynaptic changes in organotypic hippocampal slice cultures. Neurotoxicology 2008; 29:691-9. [DOI: 10.1016/j.neuro.2008.04.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2007] [Revised: 03/21/2008] [Accepted: 04/07/2008] [Indexed: 12/29/2022]
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130
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Madine J, Doig AJ, Middleton DA. Design of an N-methylated peptide inhibitor of alpha-synuclein aggregation guided by solid-state NMR. J Am Chem Soc 2008; 130:7873-81. [PMID: 18510319 DOI: 10.1021/ja075356q] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Many neurodegenerative diseases are associated with the aggregation of misfolded proteins into amyloid oligomers or fibrils that are deposited as pathological lesions within areas of the brain. An attractive therapeutic strategy for preventing or ameliorating amyloid formation is to identify agents that inhibit the onset or propagation of protein aggregation. Here we demonstrate how solid-state nuclear magnetic resonance (ssNMR) may be used to identify key residues within amyloidogenic protein sequences that may be targeted to inhibit the aggregation of the host protein. For alpha-synuclein, the major protein component of Lewy bodies associated with Parkinson's disease, we have used a combination of ssNMR and biochemical data to identify the key region for self-aggregation of the protein as residues 77-82 (VAQKTV). We used our new structural information to design a peptide derived from residues 77 to 82 of alpha-synuclein with an N-methyl group at the C-terminal residue, which was able to disrupt the aggregation of alpha-synuclein. Thus, we have shown how structural data obtained from ssNMR can guide the design of modified peptides for use as amyloid inhibitors, as a primary step toward developing therapeutic compounds for prevention and/or treatment of amyloid diseases.
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Affiliation(s)
- Jillian Madine
- School of Biological Sciences, University of Liverpool, Crown Street, Liverpool L69 7ZB, United Kingdom
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131
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Gordon LM, Nisthal A, Lee AB, Eskandari S, Ruchala P, Jung CL, Waring AJ, Mobley PW. Structural and functional properties of peptides based on the N-terminus of HIV-1 gp41 and the C-terminus of the amyloid-beta protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:2127-37. [PMID: 18515070 DOI: 10.1016/j.bbamem.2008.05.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 04/07/2008] [Accepted: 05/06/2008] [Indexed: 11/30/2022]
Abstract
Given their high alanine and glycine levels, plaque formation, alpha-helix to beta-sheet interconversion and fusogenicity, FP (i.e., the N-terminal fusion peptide of HIV-1 gp41; 23 residues) and amyloids were proposed as belonging to the same protein superfamily. Here, we further test whether FP may exhibit 'amyloid-like' characteristics, by contrasting its structural and functional properties with those of Abeta(26-42), a 17-residue peptide from the C-terminus of the amyloid-beta protein responsible for Alzheimer's. FTIR spectroscopy, electron microscopy, light scattering and predicted amyloid structure aggregation (PASTA) indicated that aqueous FP and Abeta(26-42) formed similar networked beta-sheet fibrils, although the FP fibril interactions were weaker. FP and Abeta(26-42) both lysed and aggregated human erythrocytes, with the hemolysis-onsets correlated with the conversion of alpha-helix to beta-sheet for each peptide in liposomes. Congo red (CR), a marker of amyloid plaques in situ, similarly inhibited either FP- or Abeta(26-42)-induced hemolysis, and surface plasmon resonance indicated that this may be due to direct CR-peptide binding. These findings suggest that membrane-bound beta-sheets of FP may contribute to the cytopathicity of HIV in vivo through an amyloid-type mechanism, and support the classification of HIV-1 FP as an 'amyloid homolog' (or 'amylog').
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Affiliation(s)
- Larry M Gordon
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
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132
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Esteras-Chopo A, Pastor MT, Serrano L, López de la Paz M. New Strategy for the Generation of Specific d-Peptide Amyloid Inhibitors. J Mol Biol 2008; 377:1372-81. [DOI: 10.1016/j.jmb.2008.01.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2007] [Revised: 01/02/2008] [Accepted: 01/08/2008] [Indexed: 10/22/2022]
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133
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Design, synthesis, and biological evaluation of glycine-based molecular tongs as inhibitors of Abeta1-40 aggregation in vitro. Bioorg Med Chem 2008; 16:4810-22. [PMID: 18406152 DOI: 10.1016/j.bmc.2008.03.052] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 03/13/2008] [Accepted: 03/20/2008] [Indexed: 11/21/2022]
Abstract
A series of N-terminus benzamides of glycine-based symmetric peptides, linked to m-xylylenediamine and 3,4'-oxydianiline spacers, were prepared and tested as inhibitors of beta-amyloid peptide Abeta(1-40) aggregation in vitro. Compounds with good anti-aggregating activity were detected. Polyphenolic amides showed the highest anti-aggregating activity, with IC(50) values in the micromolar range. Structure-activity relationships suggested that pi-pi stacking and hydrogen-bonding interactions play a key role in the inhibition of Abeta(1-40) self-assembly leading to amyloid fibrils.
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134
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Platt GW, Routledge KE, Homans SW, Radford SE. Fibril growth kinetics reveal a region of beta2-microglobulin important for nucleation and elongation of aggregation. J Mol Biol 2008; 378:251-63. [PMID: 18342332 PMCID: PMC2627305 DOI: 10.1016/j.jmb.2008.01.092] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 01/22/2008] [Accepted: 01/31/2008] [Indexed: 12/31/2022]
Abstract
Amyloid is a highly ordered form of aggregate comprising long, straight and unbranched proteinaceous fibrils that are formed with characteristic nucleation-dependent kinetics in vitro. Currently, the structural molecular mechanism of fibril nucleation and elongation is poorly understood. Here, we investigate the role of the sequence and structure of the initial monomeric precursor in determining the rates of nucleation and elongation of human β2-microglobulin (β2m). We describe the kinetics of seeded and spontaneous (unseeded) fibril growth of wild-type β2m and 12 variants at pH 2.5, targeting specifically an aromatic-rich region of the polypeptide chain (residues 62–70) that has been predicted to be highly amyloidogenic. The results reveal the importance of aromatic residues in this part of the β2m sequence in fibril formation under the conditions explored and show that this region of the polypeptide chain is involved in both the nucleation and the elongation phases of fibril formation. Structural analysis of the conformational properties of the unfolded monomer for each variant using NMR relaxation methods revealed that all variants contain significant non-random structure involving two hydrophobic clusters comprising regions 29–51 and 58–79, the extent of which is critically dependent on the sequence. No direct correlation was observed, however, between the extent of non-random structure in the unfolded state and the rates of fibril nucleation and elongation, suggesting that the early stages of aggregation involve significant conformational changes from the initial unfolded state. Together, the data suggest a model for β2m amyloid formation in which structurally specific interactions involving the highly hydrophobic and aromatic-rich region comprising residues 62–70 provide a complementary interface that is key to the generation of amyloid fibrils for this protein at acidic pH.
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Affiliation(s)
| | | | | | - Sheena E. Radford
- Corresponding author. Tel.: +44 113 343 3170; fax: +44 113 343 7486.
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135
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Tarawneh R, Galvin JE. Distinguishing Lewy body dementias from Alzheimer's disease. Expert Rev Neurother 2008; 7:1499-516. [PMID: 17997699 DOI: 10.1586/14737175.7.11.1499] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Lewy body dementia (LBD) is the second most common dementia after Alzheimer's disease (AD). LBD is characterized clinically by visual hallucinations, extrapyramidal symptoms, cognitive fluctuations and neuroleptic sensitivity. LBD and AD share many common features in pathology, genetics and biochemical alterations; however, correct clinical distinction between these disorders has prognostic and therapeutic implications. There are currently no definitive radiological or biological markers for LBD, but studies suggest that premorbid differences in cognitive domains and personality traits, differences in clinical presentation, and alterations in autonomic function and sleep may improve diagnosis. Cholinergic dysfunction plays a major role in both AD and LBD; however, dysfunction is greater in LBD. This may account for the more prominent hallucinations, and offers the possibility of a greater response to cholinesterase inhibitors in LBD. The treatment of LBD is symptomatic and is based on a limited number of clinical trials and extension of results from trials in AD. Current research is focused on the role of synuclein aggregation with possible roles for synuclein-derived peptides as aggregation inhibitors. Other approaches target amyloid, neuroinflammation, oxidative injury, proteolysis, lipid peroxidation and immunotherapies with variable results. Improved understanding of disease mechanisms may open new therapeutic avenues for LBD in the future.
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Affiliation(s)
- Rawan Tarawneh
- Department of Neurology, Washington University School of Medicine, St Louis, MO 63108, USA.
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136
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Marcucci E, Bayó-Puxan N, Tulla-Puche J, Spengler J, Albericio F. Cysteine-S-trityl a Key Derivative to PrepareN-Methyl Cysteines. ACTA ACUST UNITED AC 2008; 10:69-78. [DOI: 10.1021/cc7001588] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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137
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138
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Soto P, Griffin MA, Shea JE. New insights into the mechanism of Alzheimer amyloid-beta fibrillogenesis inhibition by N-methylated peptides. Biophys J 2007; 93:3015-25. [PMID: 17631541 PMCID: PMC2025672 DOI: 10.1529/biophysj.107.112086] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Alzheimer's disease is a debilitating neurodegenerative disorder associated with the abnormal self-assembly of amyloid-beta (Abeta) peptides into fibrillar species. N-methylated peptides homologous to the central hydrophobic core of the Abeta peptide are potent inhibitors of this aggregation process. In this work, we use fully atomistic molecular dynamics simulations to study the interactions of the N-methylated peptide inhibitor Abeta16-20m (Ac-Lys(16)-(Me)Leu(17)-Val(18)-(Me)Phe(19)-Phe(20)-NH(2)) with a model protofilament consisting of Alzheimer Abeta16-22 peptides. Our simulations indicate that the inhibitor peptide can bind to the protofilament at four different sites: 1), at the edge of the protofilament; 2), on the exposed face of a protofilament layer; 3), between the protofilament layers; and 4), between the protofilament strands. The different binding scenarios suggest several mechanisms of fibrillogenesis inhibition: 1), fibril inhibition of longitudinal growth (in the direction of monomer deposition); 2), fibril inhibition of lateral growth (in the direction of protofilament assembly); and 3), fibril disassembly by strand removal and perturbation of the periodicity of the protofilament (disruption of fibril morphology). Our simulations suggest that the Abeta16-20m inhibitor can act on both prefibrillar species and mature fibers and that the specific mechanism of inhibition may depend on the structural nature of the Abeta aggregate. Disassembly of the fibril can be explained by a mechanism through which the inhibitor peptides bind to disaggregated or otherwise free Abeta16-22 peptides in solution, leading to a shift in the equilibrium from a fibrillar state to one dominated by inhibitor-bound Abeta16-22 peptides.
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Affiliation(s)
- Patricia Soto
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA
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139
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Elgersma RC, Mulder GE, Kruijtzer JAW, Posthuma G, Rijkers DTS, Liskamp RMJ. Transformation of the amyloidogenic peptide amylin(20–29) into its corresponding peptoid and retropeptoid: Access to both an amyloid inhibitor and template for self-assembled supramolecular tapes. Bioorg Med Chem Lett 2007; 17:1837-42. [PMID: 17276062 DOI: 10.1016/j.bmcl.2007.01.042] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 01/12/2007] [Accepted: 01/13/2007] [Indexed: 10/23/2022]
Abstract
The highly amyloidogenic peptide sequence of amylin(20-29) was transformed into its corresponding peptoid and retropeptoid sequences to design a novel class of beta-sheet breaker peptides as amyloid inhibitors. This report describes the synthesis of the chiral peptoid building block of L-isoleucine, the solid phase synthesis of the peptoid and retropeptoid sequences of amylin(20-29), and the structural analysis of these amylin derivatives in solution by infrared spectroscopy, circular dichroism, and transmission electron microscopy. It was found that the peptoid sequence did not form amyloid fibrils or any other secondary structures and was able to inhibit amyloid formation of native amylin(20-29). Although the retropeptoid did not form amyloid fibrils it had only modest amyloid inhibitor properties since supramolecular tapes were formed.
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Affiliation(s)
- Ronald C Elgersma
- Department of Medicinal Chemistry & Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, PO Box 80082, 3508 TB Utrecht, The Netherlands
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140
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Yuan C, Berscheit HL, Huang AJW. Identification of an amyloidogenic region on keratoepithelin via synthetic peptides. FEBS Lett 2006; 581:241-7. [PMID: 17207483 DOI: 10.1016/j.febslet.2006.12.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Revised: 12/05/2006] [Accepted: 12/07/2006] [Indexed: 11/16/2022]
Abstract
Mutations of keratoepithelin (KE) gene in human chromosome 5q31 have been linked with corneal epithelial or stromal dystrophies characterized by the abnormal deposits of amyloid fibrils and/or non-amyloid aggregations in corneal tissue. We report herein that synthetic peptide containing amino acid (a.a.) residues of 515-532 of native KE protein can readily form beta-sheet-containing amyloid fibrils in vitro. Amyloid fibrils formed in various conditions from short synthetic peptides (containing a.a. 515-532 and 515-525, respectively) were characterized by thioflavin T (ThT) fluorescence assay, Congo red staining, electron microscopy (EM) and circular dichroism (CD). Triple-N-methylation of the synthetic peptides prevented the beta-sheet polymerization and related amyloid fibril formation. Comparison study with ThT fluorescence further demonstrated that synthetic peptides containing corneal dystrophy-related mutations within this region formed amyloid fibrils to various extents. Our results suggest that each individual dystrophy-related mutation by itself does not necessarily potentiate amyloid fibril formation of KE. Roles of these intrinsically amyloidogenic foci in abnormal KE aggregations and amyloid deposits of stromal corneal dystrophies await further investigation.
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Affiliation(s)
- Ching Yuan
- Department of Ophthalmology, University of Minnesota, Minneapolis, MN 55455, USA.
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141
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Heredia L, Helguera P, de Olmos S, Kedikian G, Solá Vigo F, LaFerla F, Staufenbiel M, de Olmos J, Busciglio J, Cáceres A, Lorenzo A. Phosphorylation of actin-depolymerizing factor/cofilin by LIM-kinase mediates amyloid beta-induced degeneration: a potential mechanism of neuronal dystrophy in Alzheimer's disease. J Neurosci 2006; 26:6533-42. [PMID: 16775141 PMCID: PMC6674046 DOI: 10.1523/jneurosci.5567-05.2006] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Deposition of fibrillar amyloid beta (fAbeta) plays a critical role in Alzheimer's disease (AD). We have shown recently that fAbeta-induced dystrophy requires the activation of focal adhesion proteins and the formation of aberrant focal adhesion structures, suggesting the activation of a mechanism of maladaptative plasticity in AD. Focal adhesions are actin-based structures that provide a structural link between the extracellular matrix and the cytoskeleton. To gain additional insight in the molecular mechanism of neuronal degeneration in AD, here we explored the involvement of LIM kinase 1 (LIMK1), actin-depolymerizing factor (ADF), and cofilin in Abeta-induced dystrophy. ADF/cofilin are actin-binding proteins that play a central role in actin filament dynamics, and LIMK1 is the kinase that phosphorylates and thereby inhibits ADF/cofilin. Our data indicate that treatment of hippocampal neurons with fAbeta increases the level of Ser3-phosphorylated ADF/cofilin and Thr508-phosphorylated LIMK1 (P-LIMK1), accompanied by a dramatic remodeling of actin filaments, neuritic dystrophy, and neuronal cell death. A synthetic peptide, S3 peptide, which acts as a specific competitor for ADF/cofilin phosphorylation by LIMK1, inhibited fAbeta-induced ADF/cofilin phosphorylation, preventing actin filament remodeling and neuronal degeneration, indicating the involvement of LIMK1 in Abeta-induced neuronal degeneration in vitro. Immunofluorescence analysis of AD brain showed a significant increase in the number of P-LIMK1-positive neurons in areas affected with AD pathology. P-LIMK1-positive neurons also showed early signs of AD pathology, such as intracellular Abeta and pretangle phosphorylated tau. Thus, LIMK1 activation may play a key role in AD pathology.
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142
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Zhang S, Govender T, Norström T, Arvidsson PI. An improved synthesis of Fmoc-N-methyl-alpha-amino acids. J Org Chem 2006; 70:6918-20. [PMID: 16095315 DOI: 10.1021/jo050916u] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A highly efficient and environmentally more benign synthesis of Fmoc-N-methyl-alpha-amino acids from the corresponding Fmoc-amino acid, via intermediate 5-oxazolidinones, has been developed by using Lewis acid catalysis for the reductive opening of the oxazolidinone ring.
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Affiliation(s)
- Suode Zhang
- Department of Chemistry, Organic Chemistry, Uppsala University Box 599, SE-751 24 Uppsala, Sweden
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143
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Sato T, Kienlen-Campard P, Ahmed M, Liu W, Li H, Elliott JI, Aimoto S, Constantinescu SN, Octave JN, Smith SO. Inhibitors of amyloid toxicity based on beta-sheet packing of Abeta40 and Abeta42. Biochemistry 2006; 45:5503-16. [PMID: 16634632 PMCID: PMC2593882 DOI: 10.1021/bi052485f] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Amyloid fibrils associated with Alzheimer's disease and a wide range of other neurodegenerative diseases have a cross beta-sheet structure, where main chain hydrogen bonding occurs between beta-strands in the direction of the fibril axis. The surface of the beta-sheet has pronounced ridges and grooves when the individual beta-strands have a parallel orientation and the amino acids are in-register with one another. Here we show that in Abeta amyloid fibrils, Met35 packs against Gly33 in the C-terminus of Abeta40 and against Gly37 in the C-terminus of Abeta42. These packing interactions suggest that the protofilament subunits are displaced relative to one another in the Abeta40 and Abeta42 fibril structures. We take advantage of this corrugated structure to design a new class of inhibitors that prevent fibril formation by placing alternating glycine and aromatic residues on one face of a beta-strand. We show that peptide inhibitors based on a GxFxGxF framework disrupt sheet-to-sheet packing and inhibit the formation of mature Abeta fibrils as assayed by thioflavin T fluorescence, electron microscopy, and solid-state NMR spectroscopy. The alternating large and small amino acids in the GxFxGxF sequence are complementary to the corresponding amino acids in the IxGxMxG motif found in the C-terminal sequence of Abeta40 and Abeta42. Importantly, the designed peptide inhibitors significantly reduce the toxicity induced by Abeta42 on cultured rat cortical neurons.
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Affiliation(s)
- Takeshi Sato
- Department of Biochemistry and Cell Biology, Center for Structural Biology, Stony Brook University, Stony Brook, NY 11794-5215
| | - Pascal Kienlen-Campard
- Experimental Pharmacology Unit, Université Catholique de Louvain, Brussels 1200, Belgium
| | - Mahiuddin Ahmed
- Department of Biochemistry and Cell Biology, Center for Structural Biology, Stony Brook University, Stony Brook, NY 11794-5215
| | - Wei Liu
- Department of Biochemistry and Cell Biology, Center for Structural Biology, Stony Brook University, Stony Brook, NY 11794-5215
| | - Huilin Li
- Department of Biology, Brookhaven National Laboratory, Upton, NY
| | - James I. Elliott
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520
| | - Saburo Aimoto
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Stefan N. Constantinescu
- Ludwig Institute for Cancer Research, Bruxelles 1200, Belgium. Christian de Duve Institute of Cellular Pathology, MEXP Unit, Université Catholique de Louvain, Brussels 1200, Belgium
| | - Jean-Noel Octave
- Experimental Pharmacology Unit, Université Catholique de Louvain, Brussels 1200, Belgium
| | - Steven O. Smith
- Department of Biochemistry and Cell Biology, Center for Structural Biology, Stony Brook University, Stony Brook, NY 11794-5215
- Address correspondence to: Steven O. Smith, Department of Biochemistry and Cell Biology, Center for Structural Biology, Stony Brook University, Stony Brook, NY 11794-5215, Tel. 631 632-1210; Fax. 631-632-8575.
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144
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Amer DAM, Irvine GB, El-Agnaf OMA. Inhibitors of alpha-synuclein oligomerization and toxicity: a future therapeutic strategy for Parkinson's disease and related disorders. Exp Brain Res 2006; 173:223-33. [PMID: 16733698 DOI: 10.1007/s00221-006-0539-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2006] [Accepted: 05/01/2006] [Indexed: 01/12/2023]
Abstract
An abundance of genetic, histopathological, and biochemical evidence has implicated the neuronal protein, alpha-synuclein (alpha-syn) as a key player in the development of several neurodegenerative diseases, the so-called synucleinopathies, of which Parkinson's disease (PD) is the most prevalent. Development of disease appears to be linked to events that increase the intracellular concentration of alpha-syn or cause its chemical modification, either of which can accelerate the rate at which it forms aggregates. Examples of such events include increased copy number of genes, decreased rate of degradation via the proteasome or other proteases, or altered forms of alpha-syn, such as truncations, missense mutations, or chemical modifications by oxidative reactions. Aggregated forms of the protein, especially newly formed soluble aggregates, are toxic to cells, so that one therapeutic strategy would be to reduce the rate at which such oligomerization occurs. We have therefore designed several peptides and also identified small molecules that can inhibit alpha-syn oligomerization and toxicity in vitro. These compounds could serve as lead compounds for the design of new drugs for the treatment of PD and related disorders in the future.
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Affiliation(s)
- Dena A M Amer
- Department of Biochemistry, Faculty of Medicine and Health Sciences, United Arab Emirates University, P.O.Box: 17666, Al Ain, United Arab Emirates
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145
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Elgersma RC, Meijneke T, Posthuma G, Rijkers DTS, Liskamp RMJ. Self-Assembly of Amylin(20–29) Amide-Bond Derivatives into Helical Ribbons and Peptide Nanotubes rather than Fibrils. Chemistry 2006; 12:3714-25. [PMID: 16528792 DOI: 10.1002/chem.200501374] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Uncontrolled aggregation of proteins or polypeptides can be detrimental for normal cellular processes in healthy organisms. Proteins or polypeptides that form these amyloid deposits differ in their primary sequence but share a common structural motif: the (anti)parallel beta sheet. A well-accepted approach for interfering with beta-sheet formation is the design of soluble beta-sheet peptides to disrupt the hydrogen-bonding network; this ultimately leads to the disassembly of the aggregates or fibrils. Here, we describe the synthesis, spectroscopic analysis, and aggregation behavior, imaged by electron microscopy, of several backbone-modified amylin(20-29) derivatives. It was found that these amylin derivatives were not able to form fibrils and to some extent were able to inhibit fibril growth of native amylin(20-29). However, two of the amylin peptides were able to form large supramolecular assemblies, like helical ribbons and peptide nanotubes, in which beta-sheet formation was clearly absent. This was quite unexpected since these peptides have been designed as soluble beta-sheet breakers for disrupting the characteristic hydrogen-bonding network of (anti)parallel beta sheets. The increased hydrophobicity and the presence of essential amino acid side chains in the newly designed amylin(20-29) derivatives were found to be the driving force for self-assembly into helical ribbons and peptide nanotubes. This example of controlled and desired peptide aggregation may be a strong impetus for research on bionanomaterials in which special shapes and assemblies are the focus of interest.
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Affiliation(s)
- Ronald C Elgersma
- Department of Medicinal Chemistry, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands
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146
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Ma B, Nussinov R. The stability of monomeric intermediates controls amyloid formation: Abeta25-35 and its N27Q mutant. Biophys J 2006; 90:3365-74. [PMID: 16500972 PMCID: PMC1440722 DOI: 10.1529/biophysj.105.075309] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The structure and stabilities of the intermediates affect protein folding as well as misfolding and amyloid formation. By applying Kramer's theory of barrier crossing and a Morse-function-like energy landscape, we show that intermediates with medium stability dramatically increase the rate of amyloid formation; on the other hand, very stable and very unstable intermediates sharply decrease amyloid formation. Remarkably, extensive molecular dynamics simulations and conformational energy landscape analysis of Abeta25-35 and its N27Q mutant corroborate the mathematical description. Both experimental and current simulation results indicate that the core of the amyloid structure of Abeta25-35 formed from residues 28-35. A single mutation of N27Q of Abeta25-35 makes the Abeta25-35 N27Q amyloid-free. Energy landscape calculations show that Abeta25-35 has extended intermediates with medium stability that are prone to form amyloids, whereas the extended intermediates for Abeta25-35 N27Q split into stable and very unstable species that are not disposed to form amyloids. The results explain the contribution of both alpha-helical and beta-strand intermediates to amyloid formation. The results also indicate that the structure and stability of the intermediates, as well as of the native folded and the amyloid states can be targeted in drug design. One conceivable approach is to stabilize the intermediates to deter amyloid formation.
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Affiliation(s)
- Buyong Ma
- Basic Research Program, SAIC-Frederick, Center for Cancer Research, Nanobiology Program, National Cancer Institute, FCRDC, Frederick, Maryland 21702, USA.
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147
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Boutaud O, Montine TJ, Chang L, Klein WL, Oates JA. PGH2-derived levuglandin adducts increase the neurotoxicity of amyloid beta1-42. J Neurochem 2006; 96:917-23. [PMID: 16412101 PMCID: PMC1621054 DOI: 10.1111/j.1471-4159.2005.03586.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The body of evidence indicating that oligomers of amyloid beta(1-42) (Abeta(1-42)) produce toxicity to neurons, together with our demonstration that prostaglandin H(2) (PGH(2)) oligomerizes amyloid beta(1-42), led to the examination of the neurotoxicity of amyloid beta(1-42) treated with PGH(2). The neurotoxic effects of Abeta(1-42) incubated with PGH(2) was examined in primary cultures of cerebral neurons of mice, monitoring the reduction of 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) as an indicator of cell toxicity. Whereas Abeta(1-42) itself, incubated for 24 h, has little or no effect on MTT reduction, Abeta(1-42) 24 h after exposure to PGH(2) produced a marked inhibition of MTT reduction, comparable with the inhibition resulting from Abeta(1-42) that has been oligomerized by incubation for 6 days. Similar results were obtained when Abeta(1-42) was incubated with levuglandin E(2) (LGE(2)), a reactive aldehyde formed by spontaneous rearrangement of PGH(2). The oligomers formed from reaction of Abeta(1-42) with LGE(2) exhibit immunochemical similarity with amyloid-derived diffusible ligands (ADDLs), as determined by analysis of the products of reaction of Abeta(1-42) with LGE(2) using western blotting with an antibody that is selective for ADDLs.
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Affiliation(s)
- Olivier Boutaud
- Department of Pharmacology, Vanderbilt University, Nashville 37232-6602, Tennessee, USA.
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148
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Zhang S, Prabpai S, Kongsaeree P, Arvidsson PI. Poly-N-methylated α-peptides: synthesis and X-ray structure determination of β-strand forming foldamers. Chem Commun (Camb) 2006:497-9. [PMID: 16432561 DOI: 10.1039/b513277k] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The first high resolution X-ray structure determination of poly-N-methylated alpha-peptides, a class of peptides widely used in biomedical research, is described; it shows that these molecules adopt a beta-strand conformation.
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Affiliation(s)
- Suode Zhang
- Department of Chemistry, Organic Chemistry, Uppsala University, S-75124, Uppsala, Sweden
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149
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Elgersma RC, Meijneke T, de Jong R, Brouwer AJ, Posthuma G, Rijkers DTS, Liskamp RMJ. Synthesis and structural investigations of N-alkylated β-peptidosulfonamide–peptide hybrids of the amyloidogenic amylin(20–29) sequence: implications of supramolecular folding for the design of peptide-based bionanomaterials. Org Biomol Chem 2006; 4:3587-97. [PMID: 16990934 DOI: 10.1039/b606875h] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The incorporation of a single beta-aminoethane sulfonyl amide moiety in a highly amyloidogenic peptide sequence resulted in a complete loss of amyloid fibril formation. Instead, supramolecular folding morphologies were observed. Subsequent chemoselective N-alkylation of the sulfonamide resulted in amphiphilic peptide-based hydrogelators. It was found that variation of merely the alkyl chain induced a dramatic variation in aggregation motifs such as helical ribbons and tapes, ribbons progressing to closed tubes, twisted lamellar sheets and entangled/branched fibers.
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Affiliation(s)
- Ronald C Elgersma
- Department of Medicinal Chemistry and Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, PO Box 80082, 3508 TB, Utrecht, The Netherlands
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150
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Abstract
This review considers the design, synthesis, and mechanistic assessment of peptide-based fibrillogenesis inhibitors, mainly focusing on beta-amyloid, but generalizable to other aggregating proteins and peptides. In spite of revision of the "amyloid hypothesis," the investigation and development of fibrillogenesis inhibitors remain important scientific and therapeutic goals for at least three reasons. First, it is still premature to dismiss fibrils altogether as sources of cytotoxicity. Second, a "fibrillogenesis inhibitor" is typically identified experimentally as such, but these compounds may also bind to intermediates in the fibrillogenesis pathway and have hard-to-predict consequences, including improved clearance of more cytotoxic soluble oligomers. Third, inhibitors are valuable structural probes, as the entire field of enzymology attests. Screening procedures for selection of random inhibitory sequences are briefly considered, but the bulk of the review concentrates on rationally designed fibrillogenesis inhibitors. Among these are internal segments of fibril-forming peptides, amino acid substitutions and side chain modifications of fibrillogenic domains, insertion of prolines into or adjacent to fibrillogenic domains, modification of peptide termini, modification of peptide backbone atoms (including N-methylation), peptide cyclization, use of D-amino acids in fibrillogenic domains, and nonpeptidic beta-sheet mimics. Finally, we consider methods of assaying fibrillogenesis inhibitors, including pitfalls in these assays. We consider binding of inhibitor peptides to their targets, but because this is a specific application of the more general and much larger problem of assessing protein-protein interactions, this topic is covered only briefly. Finally, we consider potential applications of inhibitor peptides to therapeutic strategies.
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