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Hu ZW, Cruceta L, Zhang S, Sun Y, Qiang W. Cross-Seeded Fibrillation Induced by Pyroglutamate-3 and Truncated Aβ 40 Variants Leads to Aβ 40 Structural Polymorphism Modulation and Elevated Toxicity. ACS Chem Neurosci 2021; 12:3625-3637. [PMID: 34524791 DOI: 10.1021/acschemneuro.1c00341] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The pathological amyloid plaques in Alzheimer's disease (AD) patients contain not only the wild-type β-amyloid (wt-Aβ) peptide sequences but also a variety of post-translationally modified variants. The pyroglutamate-3 Aβ (pyroE3-Aβ), which is generated from its truncated precursors ΔE3-Aβ, shows the highest abundance among all modified Aβ variants. Previous works have shown that pyroE3-Aβ and/or ΔE3-Aβ, compared with the wild-type sequences, led to a more rapid fibrillation process and final fibrils with higher neuronal cytotoxicity levels. However, much less is known about how the formation of pyroE3/ΔE3-Aβ fibrils would affect the amyloid deposition of wt-Aβ peptides, which are the main pathological events in AD. We show in the present work that the pyroE3/ΔE3-Aβ40 fibrils differ significantly from the wt-Aβ40 fibrils in terms of their molecular structures. When added into monomeric wt-Aβ40 peptides, these variant fibrils can cross-seed the formation of wt-Aβ40 fibrils with fibrillation kinetics that are greater than the self-seeded fibrillation of wt-Aβ40. Furthermore, the cross-seeding process modulates the molecular structures of the yielded wt-Aβ40 fibrils, which show similar features as their variant seeds. The cross-seeded fibrillation process also induces higher cytotoxicity levels compared with the self-seeded fibrillation of wt-Aβ40. Overall, our results support the hypothesis that pyroE3 and ΔE3-Aβ40 variants may serve as triggering factors of the pathological amyloid aggregation of wt-Aβ40 and may underlie the pathological significance of pyroE3/ΔE3-Aβ40 variants on the structural polymorphism of Aβ deposits.
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Affiliation(s)
- Zhi-Wen Hu
- Department of Chemistry, Binghamton University, State University of New York, Binghamton, New York 13902, United States
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, P. R. China
| | - Letticia Cruceta
- Department of Chemistry, Binghamton University, State University of New York, Binghamton, New York 13902, United States
| | - Shiyue Zhang
- Department of Chemistry, Binghamton University, State University of New York, Binghamton, New York 13902, United States
| | - Yan Sun
- Small Scale Systems Integration and Package (S3IP) Center, Binghamton University, Binghamton, New York 13902, United States
| | - Wei Qiang
- Department of Chemistry, Binghamton University, State University of New York, Binghamton, New York 13902, United States
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2
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Cheng B, Li Y, Ma L, Wang Z, Petersen RB, Zheng L, Chen Y, Huang K. Interaction between amyloidogenic proteins and biomembranes in protein misfolding diseases: Mechanisms, contributors, and therapy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1876-1888. [PMID: 29466701 DOI: 10.1016/j.bbamem.2018.02.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 02/12/2018] [Accepted: 02/13/2018] [Indexed: 12/14/2022]
Abstract
The toxic deposition of misfolded amyloidogenic proteins is associated with more than fifty protein misfolding diseases (PMDs), including Alzheimer's disease, Parkinson's disease and type 2 diabetes mellitus. Protein deposition is a multi-step process modulated by a variety of factors, in particular by membrane-protein interaction. The interaction results in permeabilization of biomembranes contributing to the cytotoxicity that leads to PMDs. Different biological and physiochemical factors, such as protein sequence, lipid composition, and chaperones, are known to affect the membrane-protein interaction. Here, we provide a comprehensive review of the mechanisms and contributing factors of the interaction between biomembranes and amyloidogenic proteins, and a summary of the therapeutic approaches to PMDs that target this interaction. This article is part of a Special Issue entitled: Protein Aggregation and Misfolding at the Cell Membrane Interface edited by Ayyalusamy Ramamoorthy.
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Affiliation(s)
- Biao Cheng
- Department of Pharmacy, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430023, China; Key Laboratory for Molecular Diagnosis of Hubei Province, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430023, China
| | - Yang Li
- Tongji School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Liang Ma
- Tongji School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Zhuoyi Wang
- Tongji School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Robert B Petersen
- Foundational Sciences, Central Michigan University College of Medicine, Mt. Pleasant, MI 48858, USA
| | - Ling Zheng
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan 430072, China
| | - Yuchen Chen
- Tongji School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Kun Huang
- Tongji School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
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3
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Differential contribution of isoaspartate post-translational modifications to the fibrillization and toxic properties of amyloid β and the Asn23 Iowa mutation. Biochem J 2015; 456:347-60. [PMID: 24028142 DOI: 10.1042/bj20130652] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mutations within the Aβ (amyloid β) peptide, especially those clustered at residues 21-23, are linked to early-onset AD (Alzheimer's disease) and primarily associated with cerebral amyloid angiopathy. The Iowa variant, a substitution of an aspartic acid residue for asparagine at position 23 (D23N), associates with widespread vascular amyloid and abundant diffuse pre-amyloid lesions significantly exceeding the incidence of mature plaques. Brain Iowa deposits consist primarily of a mixture of mutated and non-mutated Aβ species exhibiting partial aspartate isomerization at positions 1, 7 and 23. The present study analysed the contribution of the post-translational modification and the D23N mutation to the aggregation/fibrillization and cell toxicity properties of Aβ providing insight into the elicited cell death mechanisms. The induction of apoptosis by the different Aβ species correlated with their oligomerization/fibrillization propensity and β-sheet content. Although cell toxicity was primarily driven by the D23N mutation, all Aβ isoforms tested were capable, albeit at different time frames, of eliciting comparable apoptotic pathways with mitochondrial engagement and cytochrome c release to the cytoplasm in both neuronal and microvascular endothelial cells. Methazolamide, a cytochrome c release inhibitor, exerted a protective effect in both cell types, suggesting that pharmacological targeting of mitochondria may constitute a viable therapeutic avenue.
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4
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Saido TC. Metabolism of amyloid β peptide and pathogenesis of Alzheimer's disease. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2013; 89:321-39. [PMID: 23883611 PMCID: PMC3758963 DOI: 10.2183/pjab.89.321] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 06/10/2013] [Indexed: 06/02/2023]
Abstract
The conversion of what has been interpreted as "normal brain aging" to Alzheimer's disease (AD) via transition states, i.e., preclinical AD and mild cognitive impairment, appears to be a continuous process caused primarily by aging-dependent accumulation of amyloid β peptide (Aβ) in the brain. This notion however gives us a hope that, by manipulating the Aβ levels in the brain, we may be able not only to prevent and cure the disease but also to partially control some very significant aspects of brain aging. Aβ is constantly produced from its precursor and immediately catabolized under normal conditions, whereas dysmetabolism of Aβ seems to lead to pathological deposition upon aging. We have focused our attention on elucidation of the unresolved mechanism of Aβ catabolism in the brain. In this review, I describe a new approach to prevent AD development by reducing Aβ burdens in aging brains through up-regulation of the catabolic mechanism involving neprilysin that can degrade both monomeric and oligomeric forms of Aβ. The strategy of combining presymptomatic diagnosis with preventive medicine seems to be the most pragmatic in both medical and socioeconomical terms.(Communicated by Kunihiko SUZUKI, M.J.A.).
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Affiliation(s)
- Takaomi C Saido
- Laboratory for Proteolytic Neuroscience, RIKEN Brain Science Institute, Saitama, Japan.
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5
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Jana AK, Sengupta N. Adsorption mechanism and collapse propensities of the full-length, monomeric Aβ(1-42) on the surface of a single-walled carbon nanotube: a molecular dynamics simulation study. Biophys J 2012; 102:1889-96. [PMID: 22768945 DOI: 10.1016/j.bpj.2012.03.036] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 03/02/2012] [Accepted: 03/14/2012] [Indexed: 11/25/2022] Open
Abstract
Though nanomaterials such as carbon nanotubes have gained recent attention in biology and medicine, there are few studies at the single-molecule level that explore their interactions with disease-causing proteins. Using atomistic molecular-dynamics simulations, we have investigated the interactions of the monomeric Aβ(1-42) peptide with a single-walled carbon nanotube of small diameter. Starting with peptide-nanotube complexes that delineate the interactions of different segments of the peptide, we find rapid convergence in the peptide's adsorption behavior on the nanotube surface, manifested in its arrested movement, the convergence of peptide-nanotube contact areas and approach distances, and in increased peptide wrapping around the nanotube. In systems where the N-terminal domain is initially distal from nanotube, the adsorption phenomena are initiated by interactions arising from the central hydrophobic core, and precipitated by those arising from the N-terminal residues. Our simulations and free energy calculations together demonstrate that the presence of the nanotube increases the energetic favorability of the open state. We note that the observation of peptide localization could be leveraged for site-specific drug delivery, while the decreased propensity of collapse appears promising for altering kinetics of the peptide's self-assembly.
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Affiliation(s)
- Asis K Jana
- Physical Chemistry Division, National Chemical Laboratory, Pune, India
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6
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Nicholson AM, Wold LA, Walsh DM, Ferreira A. β-Amyloid carrying the Dutch mutation has diverse effects on calpain-mediated toxicity in hippocampal neurons. Mol Med 2012; 18:178-85. [PMID: 22160219 DOI: 10.2119/molmed.2011.00366] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 11/28/2011] [Indexed: 11/06/2022] Open
Abstract
Hereditary cerebral hemorrhage with amyloidosis-Dutch type is a disorder associated with a missense mutation (E693Q) in the β-amyloid (Aβ)-coding region of the amyloid precursor protein (APP). This familial disease is characterized by cognitive deficits secondary to intracerebral hemorrhage and, in some cases, progressive Alzheimer's disease (AD)-like dementia. Although this mutation was the first ever reported in the human APP gene, little is known about the molecular mechanisms underlying the direct toxic effects of this mutated Aβ on central neurons. In the present study, we assessed the role of calpain-mediated toxicity in such effects using an AD primary culture model system. Our results showed that Dutch mutant Aβ (E22Q) induced calpain-mediated cleavage of dynamin 1 and a significant decrease in synaptic contacts in mature hippocampal cultures. These synaptic deficits were similar to those induced by wild-type (WT) Aβ. In contrast, calpain-mediated tau cleavage leading to the generation of a 17-kDa neurotoxic fragment, as well as neuronal death, were significantly reduced in E22Q Aβ-treated neurons when compared with WT Aβ-treated ones. This complex regulation of the calpain-mediated toxicity pathway by E22Q Aβ could have some bearing in the pathobiology of this familial AD form.
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Affiliation(s)
- Alexandra M Nicholson
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
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7
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Ma B, Nussinov R. Polymorphic triple beta-sheet structures contribute to amide hydrogen/deuterium (H/D) exchange protection in the Alzheimer amyloid beta42 peptide. J Biol Chem 2011; 286:34244-53. [PMID: 21832091 PMCID: PMC3190809 DOI: 10.1074/jbc.m111.241141] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 07/26/2011] [Indexed: 11/06/2022] Open
Abstract
Characterization of the polymorphic structural range of Aβ oligomers is important to the understanding of the mechanisms of toxicity. Yet for highly polymorphic ensembles, experimental structural elucidation is difficult. Here, we use a combination of NMR solvent protection experiments and computational structural screening to identify major species in the amyloid conformational ensemble. We examined the polymorphic pentamer and fibril seeds of Aβ42 and its mutants and compared the theoretical backbone amide protection obtained from simulations with experimental hydrogen/deuterium (H/D) exchange protection ratio. We observed that highly flexible pentamers do not share structural similarities with fibril seed oligomers, except the turn regions. We found that a novel amyloid structural motif of a triple β-sheet, with the N-terminal residues interacting with the core (Lys(17)-Glu(22)) β-sheet region, correlates with H/D exchange protection. The triple β-sheet Aβ42 oligomer has a minimal exposure of hydrophobic residues and is further stabilized by the E22Q (Dutch) mutation in Alzheimer disease. The experimental H/D exchange solvent protection ratio implies that triple β-sheet fibrils and globulomers could coexist in the Aβ42 ensemble, pointing to a broad heterogeneous aggregate population. Our results suggest that an approach that combines computational modeling with NMR protection data can be a useful strategy for obtaining clues to the preferred conformational species of the assemblies in solution and help in alleviating experimental difficulties and consequently possible errors in the exchange data for Aβ42 fibrils.
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Affiliation(s)
- Buyong Ma
- SAIC-Frederick, Inc, Center for Cancer Research Nanobiology Program, NCI, National Institutes of Health, Frederick, Maryland 21702, USA.
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8
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Yates EA, Cucco EM, Legleiter J. Point mutations in Aβ induce polymorphic aggregates at liquid/solid interfaces. ACS Chem Neurosci 2011; 2:294-307. [PMID: 22778873 DOI: 10.1021/cn200001k] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Accepted: 04/11/2011] [Indexed: 11/30/2022] Open
Abstract
A pathological hallmark of Alzheimer's disease (AD), a late onset neurodegenerative disease, is the development of neuritic amyloid plaques, composed predominantly of aggregates of the β-amyloid (Aβ) peptide. It has been demonstrated that Aβ can aggregate into a variety of polymorphic aggregate structures under different chemical environments, and a potentially important environmental factor in dictating aggregate structure is the presence of surfaces. There are also several mutations clustered around the central hydrophobic core of Aβ (E22G Arctic mutation, E22K Italian mutation, D23N Iowa mutation, and A21G Flemish mutation). These mutations are associated with hereditary diseases ranging from almost pure cerebral amyloid angiopathy (CAA) to typical Alzheimer's disease pathology. The goal of this study was to determine how these mutations influence the morphology of Aβ aggregates under free solution conditions and at an anionic surface/liquid interface. While the rate of formation of specific aggregates was altered by mutations in Aβ under free solution conditions, the respective aggregate morphologies were similar. However, aggregation occurring directly on a negatively charged mica surface resulted in distinct aggregate morphologies formed by different mutant forms of Aβ. These studies provide insight into the potential role anionic surfaces play in dictating the formation of Aβ polymorphic aggregate structures.
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Affiliation(s)
- Elizabeth A. Yates
- The C. Eugene Bennett Department of Chemistry, ‡WVnano Initiative, §the Center for Neurosciences, West Virginia University, 217 Clark Hall, P.O. Box 6045, Morgantown, West Virginia 26506, United States
| | - Elena M. Cucco
- The C. Eugene Bennett Department of Chemistry, ‡WVnano Initiative, §the Center for Neurosciences, West Virginia University, 217 Clark Hall, P.O. Box 6045, Morgantown, West Virginia 26506, United States
| | - Justin Legleiter
- The C. Eugene Bennett Department of Chemistry, ‡WVnano Initiative, §the Center for Neurosciences, West Virginia University, 217 Clark Hall, P.O. Box 6045, Morgantown, West Virginia 26506, United States
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9
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Zhou L, Brouwers N, Benilova I, Vandersteen A, Mercken M, Van Laere K, Van Damme P, Demedts D, Van Leuven F, Sleegers K, Broersen K, Van Broeckhoven C, Vandenberghe R, De Strooper B. Amyloid precursor protein mutation E682K at the alternative β-secretase cleavage β'-site increases Aβ generation. EMBO Mol Med 2011; 3:291-302. [PMID: 21500352 PMCID: PMC3377078 DOI: 10.1002/emmm.201100138] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 02/04/2011] [Accepted: 03/06/2011] [Indexed: 11/21/2022] Open
Abstract
BACE1 cleaves the amyloid precursor protein (APP) at the β-cleavage site (Met671–Asp672) to initiate the generation of amyloid peptide Aβ. BACE1 is also known to cleave APP at a much less well-characterized β′-cleavage site (Tyr681–Glu682). We describe here the identification of a novel APP mutation E682K located at this β′-site in an early onset Alzheimer's disease (AD) case. Functional analysis revealed that this E682K mutation blocked the β′-site and shifted cleavage of APP to the β-site, causing increased Aβ production. This work demonstrates the functional importance of APP processing at the β′-site and shows how disruption of the balance between β- and β′-site cleavage may enhance the amyloidogenic processing and consequentially risk for AD. Increasing exon- and exome-based sequencing efforts will identify many more putative pathogenic mutations without conclusive segregation-based evidence in a single family. Our study shows how functional analysis of such mutations allows to determine the potential pathogenic nature of these mutations. We propose to classify the E682K mutation as probable pathogenic awaiting further independent confirmation of its association with AD in other patients.
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Affiliation(s)
- Lujia Zhou
- Department for Developmental and Molecular Genetics, VIB, Leuven, Belgium
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10
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Pifer PM, Yates EA, Legleiter J. Point mutations in Aβ result in the formation of distinct polymorphic aggregates in the presence of lipid bilayers. PLoS One 2011; 6:e16248. [PMID: 21267410 PMCID: PMC3022758 DOI: 10.1371/journal.pone.0016248] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 12/08/2010] [Indexed: 11/19/2022] Open
Abstract
A hallmark of Alzheimer's disease (AD) is the rearrangement of the β-amyloid (Aβ) peptide to a non-native conformation that promotes the formation of toxic, nanoscale aggregates. Recent studies have pointed to the role of sample preparation in creating polymorphic fibrillar species. One of many potential pathways for Aβ toxicity may be modulation of lipid membrane function on cellular surfaces. There are several mutations clustered around the central hydrophobic core of Aβ near the α-secretase cleavage site (E22G Arctic mutation, E22K Italian mutation, D23N Iowa mutation, and A21G Flemish mutation). These point mutations are associated with hereditary diseases ranging from almost pure cerebral amyloid angiopathy (CAA) to typical Alzheimer's disease pathology with plaques and tangles. We investigated how these point mutations alter Aβ aggregation in the presence of supported lipid membranes comprised of total brain lipid extract. Brain lipid extract bilayers were used as a physiologically relevant model of a neuronal cell surface. Intact lipid bilayers were exposed to predominantly monomeric preparations of Wild Type or different mutant forms of Aβ, and atomic force microscopy was used to monitor aggregate formation and morphology as well as bilayer integrity over a 12 hour period. The goal of this study was to determine how point mutations in Aβ, which alter peptide charge and hydrophobic character, influence interactions between Aβ and the lipid surface. While fibril morphology did not appear to be significantly altered when mutants were prepped similarly and incubated under free solution conditions, aggregation in the lipid membranes resulted in a variety of polymorphic aggregates in a mutation dependent manner. The mutant peptides also had a variable ability to disrupt bilayer integrity.
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Affiliation(s)
- Phillip M. Pifer
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia, United States of America
| | - Elizabeth A. Yates
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia, United States of America
| | - Justin Legleiter
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia, United States of America
- WVnano Initiative, West Virginia University, Morgantown, West Virginia, United States of America
- The Center for Neurosciences, West Virginia University, Morgantown, West Virginia, United States of America
- * E-mail:
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11
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Sureshbabu N, Kirubagaran R, Thangarajah H, Malar EJP, Jayakumar R. Lipid-induced conformational transition of amyloid beta peptide fragments. J Mol Neurosci 2010; 41:368-82. [PMID: 20480256 DOI: 10.1007/s12031-010-9380-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Accepted: 04/20/2010] [Indexed: 10/19/2022]
Abstract
Conformational transition of soluble monomeric amyloid beta-peptide (Abeta) into oligomeric and protofibrillar aggregates plays a key role in the pathogenesis of Alzheimer's disease (AD). One of the central questions surrounding the molecular pathophysiology of AD is how the soluble Abeta is converted into its aggregated toxic form. A more detailed understanding of the conformational transitions involved in the self-assembly of Abeta may facilitate the design of inhibitors of aggregation. In this study, we evaluated the wild-type (WT) Abeta 16-28 peptide (KLVFFAEDVGSNK) and its associated mutants, including A21G (Flemish), E22K (Italian), E22Q (Dutch), and E22G (Arctic) mutants, by examining, in particular, their aggregation kinetics in the presence and in the absence of negatively charged and zwitterionic lipids. Circular dichroic and thioflavin T fluorescence studies indicated that the WT peptide undergoes a rapid conformational transition into beta-sheet structure in solution, whereas the Arctic and Dutch variants show a markedly rapid transition into beta-sheet structure in the presence of negatively charged lipids. These results provide strong evidence suggesting that the reduction in net charge, with a concurrent increase in the net hydrophobicity of the peptide alone or when complexed with lipid in solution, determines the rate of aggregate formation.
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Affiliation(s)
- Nagarajan Sureshbabu
- Bio-Organic and Neurochemistry Laboratory, Central Leather Research Institute, Adyar, Chennai 600020, India
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12
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Crews L, Rockenstein E, Masliah E. APP transgenic modeling of Alzheimer's disease: mechanisms of neurodegeneration and aberrant neurogenesis. Brain Struct Funct 2009; 214:111-26. [PMID: 20091183 PMCID: PMC2847155 DOI: 10.1007/s00429-009-0232-6] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 11/11/2009] [Indexed: 12/13/2022]
Abstract
Neurodegenerative disorders of the aging population affect over 5 million people in the US and Europe alone. The common feature is the progressive accumulation of misfolded proteins with the formation of toxic oligomers. Alzheimer’s disease (AD) is characterized by cognitive impairment, progressive degeneration of neuronal populations in the neocortex and limbic system, and formation of amyloid plaques and neurofibrillary tangles. Amyloid-β (Aβ) is the product of proteolysis of amyloid precursor protein (APP) by β and γ-secretase enzymes. The neurodegenerative process in AD initiates with axonal and synaptic damage and is associated with progressive accumulation of toxic Aβ oligomers in the intracellular and extracellular space. In addition, neurodegeneration in AD is associated with alterations in neurogenesis. Aβ accumulation is the consequence of an altered balance between protein synthesis, aggregation rate, and clearance. Identification of genetic mutations in APP associated with familial forms of AD and gene polymorphisms associated with the more common sporadic variants of AD has led to the development of transgenic (tg) and knock out rodents as well as viral vector driven models of AD. While APP tg murine models with mutations in the N- and C-terminal flanking regions of Aβ are characterized by increased Aβ production with plaque formation, mutations in the mid-segment of Aβ result in increased formation of oligomers, and mutations toward the C-terminus (E22Q) segment results in amyloid angiopathy. Similar to AD, in APP tg models bearing familial mutations, formation of Aβ oligomers results in defective plasticity in the perforant pathway, selective neuronal degeneration, and alterations in neurogenesis. Promising results have been obtained utilizing APP tg models of AD to develop therapies including the use of β- and γ-secretase inhibitors, immunization, and stimulating neurogenesis.
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Affiliation(s)
- Leslie Crews
- Department of Pathology, University of California, San Diego, La Jolla, CA, USA
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Wirths O, Breyhan H, Cynis H, Schilling S, Demuth HU, Bayer TA. Intraneuronal pyroglutamate-Abeta 3-42 triggers neurodegeneration and lethal neurological deficits in a transgenic mouse model. Acta Neuropathol 2009; 118:487-96. [PMID: 19547991 PMCID: PMC2737116 DOI: 10.1007/s00401-009-0557-5] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Revised: 06/03/2009] [Accepted: 06/06/2009] [Indexed: 11/11/2022]
Abstract
It is well established that only a fraction of Aβ peptides in the brain of Alzheimer’s disease (AD) patients start with N-terminal aspartate (Aβ1D) which is generated by proteolytic processing of amyloid precursor protein (APP) by BACE. N-terminally truncated and pyroglutamate modified Aβ starting at position 3 and ending with amino acid 42 [Aβ3(pE)–42] have been previously shown to represent a major species in the brain of AD patients. When compared with Aβ1–42, this peptide has stronger aggregation propensity and increased toxicity in vitro. Although it is unknown which peptidases remove the first two N-terminal amino acids, the cyclization of Aβ at N-terminal glutamate can be catalyzed in vitro. Here, we show that Aβ3(pE)–42 induces neurodegeneration and concomitant neurological deficits in a novel mouse model (TBA2 transgenic mice). Although TBA2 transgenic mice exhibit a strong neuronal expression of Aβ3–42 predominantly in hippocampus and cerebellum, few plaques were found in the cortex, cerebellum, brain stem and thalamus. The levels of converted Aβ3(pE)-42 in TBA2 mice were comparable to the APP/PS1KI mouse model with robust neuron loss and associated behavioral deficits. Eight weeks after birth TBA2 mice developed massive neurological impairments together with abundant loss of Purkinje cells. Although the TBA2 model lacks important AD-typical neuropathological features like tangles and hippocampal degeneration, it clearly demonstrates that intraneuronal Aβ3(pE)–42 is neurotoxic in vivo.
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van Groen T, Kadish I, Wiesehan K, Funke S, Willbold D. In vitro and in vivo Staining Characteristics of Small, Fluorescent, Aβ42-Binding D-Enantiomeric Peptides in Transgenic AD Mouse Models. ChemMedChem 2009; 4:276-82. [DOI: 10.1002/cmdc.200800289] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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15
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Wang SSS, Wu JW, Yamamoto S, Liu HS. Diseases of protein aggregation and the hunt for potential pharmacological agents. Biotechnol J 2008; 3:165-92. [DOI: 10.1002/biot.200700065] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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16
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Saido TC, Iwata N. Metabolism of amyloid beta peptide and pathogenesis of Alzheimer's disease. Towards presymptomatic diagnosis, prevention and therapy. Neurosci Res 2006; 54:235-53. [PMID: 16457902 DOI: 10.1016/j.neures.2005.12.015] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2005] [Revised: 12/19/2005] [Accepted: 12/27/2005] [Indexed: 12/29/2022]
Abstract
The conversion of what has been interpreted as "normal brain aging" to Alzheimer's disease (AD) via a transition state, i.e. mild cognitive impairment, appears to be a continuous process caused primarily by aging-dependent accumulation of amyloid beta peptide (Abeta) in the brain. This notion give us a hope that, by manipulating the Abeta levels in the brain, we may be able not only to prevent and cure the disease but also to partially control some very significant aspects of brain aging. Abeta is constantly produced from its precursor and immediately catabolized under normal conditions, whereas dysmetabolism of Abeta seems to lead to pathological deposition upon aging. We have focused our attention on elucidation of the unresolved mechanism of Abeta catabolism in the brain. In this review, we describe a new approach to prevent AD development by reducing Abeta burdens in aging brains through up-regulation the catabolic mechanism involving neprilysin that can degrade both monomeric and oligomeric forms of Abeta. The strategy of combining presymptomatic diagnosis with preventive medicine seems to be the most pragmatic in both medical and socio-economical terms. We also introduce a novel non-invasive amyloid imaging approach using a high-power magnetic resonance imaging (MRI) for the presymptomatic diagnosis of AD.
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Affiliation(s)
- Takaomi C Saido
- Laboratory for Proteolytic Neuroscience, RIKEN Brain Science Institute, Wako-shi, Saitama, Japan.
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17
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Onoue S, Iwasa S, Kojima T, Katoh F, Debari K, Koh K, Matsuda Y, Yajima T. Structural transition of glucagon in the concentrated solution observed by electrophoretic and spectroscopic techniques. J Chromatogr A 2005; 1109:167-73. [PMID: 16364337 DOI: 10.1016/j.chroma.2005.11.130] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Revised: 11/26/2005] [Accepted: 11/30/2005] [Indexed: 11/26/2022]
Abstract
Glucagon, a polypeptide hormone consisting of 29 amino acid residues, tends to form gel-like fibrillar aggregates, and the glucagon fibril, as well as other pathologically related fibrils including prion, amylin, and beta-amyloid, have been found to be cytotoxic through the activation of apoptotic signaling pathways. To understand the aggregation properties of glucagon fibril, we have characterized and compared the physicochemical properties of glucagon, secretin, a member of the glucagon superfamily, and amylin using analytical techniques including capillary electrophoresis (CE), circular dichroism (CD), FT-IR, FT-Raman, transmission electron microscopy (TEM), and beta-sheet-imaging probe. Aging treatment of glucagon resulted in the formation of fibrillar aggregates in time- and concentration-dependent manner, and FT-IR and FT-Raman analyses showed the spectral shift of amide I band, suggesting the conformational changes from alpha-helix to beta-sheet structure. Interestingly, secretin, having high sequential and secondary structural homology with glucagon, did not generate the fibrillar aggregates at the conditions tested. In addition, we evaluated the association state of glucagon at various pHs raging from pH 2.0 to 3.5 using CE. Based on the CE data, the rate constants of glucagon aggregation were calculated to be 0.002 +/- 0.004/h and 0.080 +/- 0.011/h for aging at pH 2.0 and 3.5, respectively, suggesting the pH dependence of self-association. CE showed the potential to separate and detect the glucagon aggregates and intermediates during aging process.
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Affiliation(s)
- Satomi Onoue
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, Funabashi, Chiba 274-8510, Japan.
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18
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Onoue S, Ohshima K, Debari K, Koh K, Shioda S, Iwasa S, Kashimoto K, Yajima T. Mishandling of the therapeutic peptide glucagon generates cytotoxic amyloidogenic fibrils. Pharm Res 2005; 21:1274-83. [PMID: 15290870 DOI: 10.1023/b:pham.0000033016.36825.2c] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE Some therapeutic peptides exhibit amyloidogenic properties that cause insolubility and cytotoxicity against neuronal cells in vitro. Here, we characterize the conformational change in monomeric therapeutic peptide to its fibrillar aggregate in order to prevent amyloidogenic formation during clinical application. METHODS Therapeutic peptides including glucagon, porcine secretin, and salmon calcitonin were dissolved in acidic solution at concentrations ranging from 1 mg/ml to 80 mg/ml and then aged at 37 degrees C. Amyloidogenic properties were assessed by circular dichroism (CD), electron microscopy (EM), staining with beta-sheet-specific dyes, and size-exclusion chromatography (SEC). Cytotoxic characteristics were determined concomitantly. RESULTS By aging at 2.5 mg/ml or higher for 24 h, monomeric glucagon was converted to fibrillar aggregates consisting of a beta-sheet-rich structure with multimeric states of glucagon. Although no aggregation was observed by aging at the clinical concentration of 1 mg/ml for 1 day, 30-day aging resulted in the generation of fibrillar aggregates. The addition of anti-glucagon serum significantly inhibited fibrillar conversion of monomeric glucagon. Glucagon fibrils induced significant cell death and activated an apoptotic enzyme, caspase-3, in PC12 cells and NIH-3T3 cells. Caspase inhibitors attenuated this toxicity in a dose-dependent manner, indicating the involvement of apoptotic signaling pathways in the fibrillar formation of glucagon. On the contrary to glucagon, salmon calcitonin exhibited aggregation at a much higher concentration of 40 mg/ml and secretin showed no aggregation at the concentration as high as 75 mg/ml. CONCLUSIONS These results indicated that glucagon was self-associated by its beta-sheet-rich intermolecular structure during the aging process under concentrated conditions to induce fibrillar aggregates. Glucagon has the same amyloidogenic propensities as pathologically related peptides such as beta-amyloid (Abeta)1-42 and prion protein fragment (PrP)106-126 including conformational change to a beta-sheet-rich structure and cytotoxic effects by activating caspases. These findings suggest that inappropriate preparation and application of therapeutic glucagon may cause undesirable insoluble products and side effects such as amyloidosis in clinical application.
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Affiliation(s)
- Satomi Onoue
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, Funabashi, Chiba, Japan.
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19
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Rowan MJ, Klyubin I, Wang Q, Anwyl R. Mechanisms of the inhibitory effects of amyloid β-protein on synaptic plasticity. Exp Gerontol 2004; 39:1661-7. [PMID: 15582282 DOI: 10.1016/j.exger.2004.06.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2004] [Accepted: 06/09/2004] [Indexed: 12/29/2022]
Abstract
Alzheimer's disease can be considered a protein misfolding disease. In particular, inappropriate processing of a proteolytic fragment of amyloid precursor protein, amyloid beta-protein (Abeta), in early stages of Alzheimer's disease may lead to stabilization of small oligomers that are highly mobile and have a potential to be extremely toxic assemblies. Recently, the importance of such soluble species of Abeta in triggering synaptic dysfunction, long before neuronal loss occurs, has become apparent. Animal models have revealed that plasticity of hippocampal excitatory synaptic transmission is relatively selectively vulnerable to Abeta both in vitro and in vivo. This review focuses on the mechanisms of Abeta inhibition of long-term potentiation at synapses in the rodent hippocampus from two complimentary perspectives. Firstly, we examine evidence that the synaptic activity of this peptide resides primarily in oligomeric rather than monomeric or fibrillar Abeta species. Secondly, the importance of different oxidative/nitrosative stress-linked cascades including JNK, p38 MAPK and NADPH oxidase/iNOS-generated reactive oxygen/nitrogen free radicals in mediating the inhibition of LTP by Abeta is emphasised. These mechanistic studies provide a plausible explanation for the sensitivity of hippocampus-dependent memory to impairment in the early preclinical stages of Alzheimer's disease.
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Affiliation(s)
- Michael J Rowan
- Trinity College Institute of Neuroscience, Department of Pharmacology and Therapeutics, Trinity College, Biotechnology Building, Dublin 2, Ireland.
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20
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Linding R, Schymkowitz J, Rousseau F, Diella F, Serrano L. A Comparative Study of the Relationship Between Protein Structure and β-Aggregation in Globular and Intrinsically Disordered Proteins. J Mol Biol 2004; 342:345-53. [PMID: 15313629 DOI: 10.1016/j.jmb.2004.06.088] [Citation(s) in RCA: 291] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2004] [Revised: 06/21/2004] [Accepted: 06/22/2004] [Indexed: 10/26/2022]
Abstract
A growing number of proteins are being identified that are biologically active though intrinsically disordered, in sharp contrast with the classic notion that proteins require a well-defined globular structure in order to be functional. At the same time recent work showed that aggregation and amyloidosis are initiated in amino acid sequences that have specific physico-chemical properties in terms of secondary structure propensities, hydrophobicity and charge. In intrinsically disordered proteins (IDPs) such sequences would be almost exclusively solvent-exposed and therefore cause serious solubility problems. Further, some IDPs such as the human prion protein, synuclein and Tau protein are related to major protein conformational diseases. However, this scenario contrasts with the large number of unstructured proteins identified, especially in higher eukaryotes, and the fact that the solubility of these proteins is often particularly good. We have used the algorithm TANGO to compare the beta aggregation tendency of a set of globular proteins derived from SCOP and a set of 296 experimentally verified, non-redundant IDPs but also with a set of IDPs predicted by the algorithms DisEMBL and GlobPlot. Our analysis shows that the beta-aggregation propensity of all-alpha, all-beta and mixed alpha/beta globular proteins as well as membrane-associated proteins is fairly similar. This illustrates firstly that globular structures possess an appreciable amount of structural frustration and secondly that beta-aggregation is not determined by hydrophobicity and beta-sheet propensity alone. We also show that globular proteins contain almost three times as much aggregation nucleating regions as IDPs and that the formation of highly structured globular proteins comes at the cost of a higher beta-aggregation propensity because both structure and aggregation obey very similar physico-chemical constraints. Finally, we discuss the fact that although IDPs have a much lower aggregation propensity than globular proteins, this does not necessarily mean that they have a lower potential for amyloidosis.
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Affiliation(s)
- Rune Linding
- European Molecular Biology Laboratory, Programme for Structural and Computational biology, Meyerhofstr 1, D-69117 Heidelberg, Germany
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21
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Qahwash I, He W, Tomasselli A, Kletzien RF, Yan R. Processing Amyloid Precursor Protein at the β-Site Requires Proper Orientation to Be Accessed by BACE1. J Biol Chem 2004; 279:39010-6. [PMID: 15234966 DOI: 10.1074/jbc.m407101200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Membrane-bound BACE1 naturally cleaves its transmembrane substrate amyloid precursor protein (APP) at the two adjacent beta- and beta'-sites. Cleavage at these two sites generates the heterogeneous N-terminal end of APP C-terminal fragments that are further processed by gamma-secretase to release Abeta-(1-40/42) or Abeta-(11-40/42). The significance underlying Abeta-(11-40/42) in Alzheimer's disease pathogenesis has remained to be experimentally elucidated, but increased production of Abeta-(1-40/42) has been broadly demonstrated to contribute to amyloid depositions in senile plaques. In this study, we show that the cleavage of APP at the beta-site by BACE1 is readily disrupted through limited structural twists, whereas the beta'-site is relatively better positioned to gain access to the BACE1 catalytic cavity. Radical insertion or deletion of residues between beta- and beta'-site also favors cleavage of APP at the beta'-site. On the other hand, either lengthening or shortening the loop region of BACE1 has a minor impact on the selective cleavage of APP at these two adjacent sites, but significantly shortening the loop region impairs the ability of BACE1 to process APP at both sites. Thus, processing of APP by BACE1 is clearly dependent on a mutual structural compatibility in addition to the sequence feature. The knowledge gained from this study will potentially offer an opportunity for rational design of small molecule drugs to block the cleavage of APP specifically at the beta-site while not disturbing the functions of other cellular aspartyl proteases.
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Affiliation(s)
- Isam Qahwash
- Cell and Molecular Biology, Protein Sciences, Pharmacia Corporation, Kalamazoo, Michigan 49007, USA
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22
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Klyubin I, Walsh DM, Cullen WK, Fadeeva JV, Anwyl R, Selkoe DJ, Rowan MJ. Soluble Arctic amyloid beta protein inhibits hippocampal long-term potentiation in vivo. Eur J Neurosci 2004; 19:2839-46. [PMID: 15147317 DOI: 10.1111/j.1460-9568.2004.03389.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Mutations in the amyloid precursor protein that result in substitutions of glutamic acid at residue 22 of the amyloid beta protein (A beta) with glutamine (Q22, Dutch) or glycine (G22, Arctic) cause aggressive familial neurological diseases characterized by cerebrovascular haemorrhages or Alzheimer's-type dementia, respectively. The present study compared the ability of these peptides to block long-term potentiation (LTP) of glutamatergic transmission in the hippocampus in vivo. The effects of intracerebroventricular injection of wild-type, Q22 and G22 A beta(1-40) peptides were examined in the CA1 area of urethane-anaesthetized rats. Both mutant peptides were approximately 100-fold more potent than wild-type A beta at inhibiting LTP induced by high-frequency stimulation when solutions of A beta were freshly prepared. Fibrillar material, as determined by electron microscopy, was obvious in all these peptide solutions and exhibited appreciable Congo Red binding, particularly for A beta(1-40)G22 and A beta(1-40)Q22. A soluble fraction of A beta(1-40)G22, obtained following high-speed centrifugation, retained full activity of the peptide solution to inhibit LTP, providing strong evidence that in the case of the Arctic disease a soluble nonfibrillar form of A beta may represent the primary mediator of A beta-related cognitive deficits, particularly early in the disease. In contrast, nonfibrillar soluble A beta(1-40)Q22 supernatant solution was approximately 10-fold less potent at inhibiting LTP than A beta(1-40)G22, a finding consistent with fibrillar A beta contributing to the inhibition of LTP by the Dutch peptide.
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Affiliation(s)
- Igor Klyubin
- Trinity College Institute of Neuroscience, and Department of Pharmacology and Therapeutics, Trinity College, Dublin 2, Ireland
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23
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Abstract
Cerebral amyloid angiopathy (CAA) is the result of the deposition of an amyloidogenic protein in cortical and leptomeningeal vessels. The most common type of CAA is caused by amyloid beta-protein (Abeta), which is particularly associated with Alzheimer's disease (AD). Excessive Abeta-CAA formation can be caused by several mutations in the Abeta precursor protein and presenilin genes. The origin of Abeta in CAA is likely to be neuronal, although cerebrovascular cells or the circulation cannot be excluded as a source. Despite the apparent similarity, the pathogenesis of CAA appears to differ from that of senile plaques in several aspects, including the mechanism of Abeta-induced cellular toxicity, the extent of inflammatory reaction and the role of oxidative stress. Therefore, therapeutic strategies for AD should, at least in part, also target CAA. Moreover, CAA and cerebrovascular disease (CVD) may set a lower threshold for AD-like changes to cause dementia and may even cause dementia on its own, since patients with AD and CAA and/or CVD appear to be more cognitively impaired than patients with only AD. In conclusion, the precise impact of CAA on AD or dementia remains unclear, however, its role may have been underestimated in the past, and more extensive studies of in vitro and in vivo models for CAA will be needed to elucidate the importance of CAA-specific approaches in designing intervention strategies for AD.
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Affiliation(s)
- Annemieke A M Rensink
- Department of Neurology, Laboratory of Pediatrics and Neurology, University Medical Center, 319, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
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24
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Manoutcharian K, Acero G, Munguia ME, Montero JA, Govezensky T, Cao C, Ugen K, Gevorkian G. Amyloid-beta peptide-specific single chain Fv antibodies isolated from an immune phage display library. J Neuroimmunol 2003; 145:12-7. [PMID: 14644026 DOI: 10.1016/j.jneuroim.2003.08.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A single-chain fragment variable (scFv) antibody library displayed on phage was constructed using spleen cells from mice immunized with human amyloid-beta peptide (Abeta42). This first anti-Abeta42 scFv immune antibody library was selected against human Abeta42. A number of positive clones were obtained, and sequences of VH and Vkappa genes were analyzed using ExPASy and BLAST computer tools. This analysis revealed that only two unique clones with identical VH and Vkappa complementarity determining region (CDR) (except HCDR2) and identical germline genes were selected, indicating that oligoclonal immune response was occurring in Abeta42-immunized mice. Abeta42-specific scFv antibodies selected from this first immune anti-Abeta42 phage antibody library may be an important tool for the development of therapeutic molecules for Alzheimer's disease (AD).
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Affiliation(s)
- K Manoutcharian
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, AP 70228, México DF, 04510, Mexico
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25
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Qahwash I, Weiland KL, Lu Y, Sarver RW, Kletzien RF, Yan R. Identification of a mutant amyloid peptide that predominantly forms neurotoxic protofibrillar aggregates. J Biol Chem 2003; 278:23187-95. [PMID: 12684519 DOI: 10.1074/jbc.m213298200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The amyloid peptide (Abeta), derived from the proteolytic cleavage of the amyloid precursor protein (APP) by beta- and gamma-secretases, undergoes multistage assemblies to fibrillar depositions in the Alzheimer's brains. Abeta protofibrils were previously identified as an intermediate preceding insoluble fibrils. While characterizing a synthetic Abeta variant named EV40 that has mutations in the first two amino acids (D1E/A2V), we discerned unusual aggregation profiles of this variant. In comparison of the fibrillogenesis and cellular toxicity of EV40 to the wild-type Abeta peptide (Abeta40), we found that Abeta40 formed long fibrillar aggregates while EV40 formed only protofibrillar aggregates under the same in vitro incubation conditions. Cellular toxicity assays indicated that EV40 was slightly more toxic than Abeta40 to human neuroblastoma SHEP cells, rat primary cortical, and hippocampal neurons. Like Abeta40, the neurotoxicity of the protofibrillar EV40 could be partially attributed to apoptosis since multiple caspases such as caspase-9 were activated after SHEP cells were challenged with toxic concentrations of EV40. This suggested that apoptosis-induced neuronal loss might occur before extensive depositions of long amyloid fibrils in AD brains. This study has been the first to show that a mutated Abeta peptide formed only protofibrillar species and mutations of the amyloid peptide at the N-terminal side affect the dynamic amyloid fibrillogenesis. Thus, the identification of EV40 may lead to further understanding of the structural perturbation of Abeta to its fibrillation.
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Affiliation(s)
- Isam Qahwash
- Department of Cell & Molecular Biology, Pharmacia Corporation, Kalamazoo, Michigan 49007, USA
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26
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Kumar-Singh S, Julliams A, Nuydens R, Ceuterick C, Labeur C, Serneels S, Vennekens K, Van Osta P, Geerts H, De Strooper B, Van Broeckhoven C. In vitro studies of Flemish, Dutch, and wild-type beta-amyloid provide evidence for two-staged neurotoxicity. Neurobiol Dis 2002; 11:330-40. [PMID: 12505425 DOI: 10.1006/nbdi.2002.0529] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations in the beta-amyloid (Abeta) sequence of the amyloid precursor protein gene (APP) present with variable disease phenotypes. While patients with the Dutch APP mutation (E693Q) have predominantly hemorrhagic strokes, Flemish APP (A692G) patients develop both strokes and Alzheimer's disease (AD). To determine whether these diverse clinical and pathological presentations are due to mutant Abeta or APP, we studied the effect of Flemish, Dutch, and wild-type Abeta/APP on phosphorylation of specific tau epitopes observed in AD. No effect was observed in differentiated SH-SY5Y cells either stably expressing APP or treated with synthetic Abeta(12-42). However, we did observe a paradoxical temporal difference in the neurotoxic potential of mutant and wild-type Abeta. While long 24-h incubation at physiological levels of Abeta (2 microM) showed a higher amount of apoptosis for Dutch Abeta, a short 2-h incubation showed elevated apoptosis for Flemish and wild-type Abeta. The altered aggregating properties of Abeta, with Dutch Abeta aggregating faster and Flemish Abeta slower than wild type, elucidated a discrete two-phase Abeta neurotoxicity. We propose here that, at least in vitro, Abeta might be neurotoxic in an initial phase due to its soluble oligomeric or other early toxic Abeta intermediate(s), which is perhaps distinct from the late neurotoxicity incurred by aggregated larger assemblies of Abeta.
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Affiliation(s)
- Samir Kumar-Singh
- Department of Molecular Genetics, Flanders Interuniversity Institute for Biotechnology, Born-Bunge Foundation, University of Antwerp, B-2610 Antwerp, Belgium
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27
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Sidera C, Liu C, Austen B. Pro-domain removal in ASP-2 and the cleavage of the amyloid precursor are influenced by pH. BMC BIOCHEMISTRY 2002; 3:25. [PMID: 12204094 PMCID: PMC126479 DOI: 10.1186/1471-2091-3-25] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2002] [Accepted: 08/31/2002] [Indexed: 11/23/2022]
Abstract
BACKGROUND One of the signatures of Alzheimer's disease is the accumulation of aggregated amyloid protein, Abeta, in the brain. Abeta arises from cleavage of the Amyloid Precursor protein by beta and gamma secretases, which present attractive candidates for therapeutic targeting. Two beta-secretase candidates, ASP-1 and ASP-2, were identified as aspartic proteases, both of which cleave the amyloid precursor at the beta-site. These are produced as immature transmembrane proteins containing a pro-segment. RESULTS ASP-2 expressed in HEK293-cells cleaved the Swedish mutant amyloid precursor at different beta-sites at different pHs in vitro. Recent reports show that furin cleaves the pro-peptide of ASP-2, whereas ASP-1 undergoes auto-catalysis. We show that purified recombinant ASP-2 cleaves its own pro-peptide at ph 5 but not pH 8.5 as seen by mass spectrometry, electrophoresis and N-terminal sequencing. CONCLUSION We suggest that ASP-2 processing as well as activity are influenced by pH, and hence the cellular localisation of the protein may have profound effects on the production of Abeta. These factors should be taken into consideration in the design of potential inhibitors for these enzymes.
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Affiliation(s)
- Christina Sidera
- Neurodegeneration Unit, Dept of Surgery, St George's Hospital Medical School, Cranmer Terrace, London SW 17 ORE, UK
| | - Chibuu Liu
- Neurodegeneration Unit, Dept of Surgery, St George's Hospital Medical School, Cranmer Terrace, London SW 17 ORE, UK
| | - Brian Austen
- Neurodegeneration Unit, Dept of Surgery, St George's Hospital Medical School, Cranmer Terrace, London SW 17 ORE, UK
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28
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Dahlgren KN, Manelli AM, Stine WB, Baker LK, Krafft GA, LaDu MJ. Oligomeric and fibrillar species of amyloid-beta peptides differentially affect neuronal viability. J Biol Chem 2002; 277:32046-53. [PMID: 12058030 DOI: 10.1074/jbc.m201750200] [Citation(s) in RCA: 1119] [Impact Index Per Article: 50.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Genetic evidence predicts a causative role for amyloid-beta (A beta) in Alzheimer's disease. Recent debate has focused on whether fibrils (amyloid) or soluble oligomers of A beta are the active species that contribute to neurodegeneration and dementia. We developed two aggregation protocols for the consistent production of stable oligomeric or fibrillar preparations of A beta-(1-42). Here we report that oligomers inhibit neuronal viability 10-fold more than fibrils and approximately 40-fold more than unaggregated peptide, with oligomeric A beta-(1-42)-induced inhibition significant at 10 nm. Under A beta-(1-42) oligomer- and fibril-forming conditions, A beta-(1-40) remains predominantly as unassembled monomer and had significantly less effect on neuronal viability than preparations of A beta-(1-42). We applied the aggregation protocols developed for wild type A beta-(1-42) to A beta-(1-42) with the Dutch (E22Q) or Arctic (E22G) mutations. Oligomeric preparations of the mutations exhibited extensive protofibril and fibril formation, respectively, but were not consistently different from wild type A beta-(1-42) in terms of inhibition of neuronal viability. However, fibrillar preparations of the mutants appeared larger and induced significantly more inhibition of neuronal viability than wild type A beta-(1-42) fibril preparations. These data demonstrate that protocols developed to produce oligomeric and fibrillar A beta-(1-42) are useful in distinguishing the structural and functional differences between A beta-(1-42) and A beta-(1-40) and genetic mutations of A beta-(1-42).
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Affiliation(s)
- Karie N Dahlgren
- Department of Medicine, Evanston Northwestern Healthcare Research Institute, Evanston, Illinois 60201, USA
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29
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Sennvik K, Nilsberth C, Stenh C, Lannfelt L, Benedikz E. The Arctic Alzheimer mutation enhances sensitivity to toxic stress in human neuroblastoma cells. Neurosci Lett 2002; 326:51-5. [PMID: 12052536 DOI: 10.1016/s0304-3940(02)00305-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The E693G (Arctic) mutation of the amyloid precursor protein was recently found to lead to early-onset Alzheimer's disease in a Swedish family. In the present study, we report that the Arctic mutation decreases cell viability in human neuroblastoma cells. The cell viability, as measured by the MTT assay and propidium iodide staining, was further compromised following exposure to calcium ionophore A23187, microtubule-binding colchicine or oxidative stress inducer hydrogen peroxide. The manner of cell death was found to be apoptotic. During apoptosis, cells with the Arctic mutation also decreased their secretion of beta-secretase cleaved amyloid precursor protein. The enhanced sensitivity to toxic stress in cells with the Arctic mutation most likely contributes to the pathogenic pathway leading to Alzheimer's disease.
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Affiliation(s)
- Kristina Sennvik
- Section of Experimental Geriatrics, Neurotec, Karolinska Institutet, KFC Novum, plan 4, 141 86 Huddinge, Sweden.
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