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Viles JH. Imaging Amyloid-β Membrane Interactions: Ion-Channel Pores and Lipid-Bilayer Permeability in Alzheimer's Disease. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 135:e202215785. [PMID: 38515735 PMCID: PMC10952214 DOI: 10.1002/ange.202215785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Indexed: 03/08/2023]
Abstract
The accumulation of the amyloid-β peptides (Aβ) is central to the development of Alzheimer's disease. The mechanism by which Aβ triggers a cascade of events that leads to dementia is a topic of intense investigation. Aβ self-associates into a series of complex assemblies with different structural and biophysical properties. It is the interaction of these oligomeric, protofibril and fibrillar assemblies with lipid membranes, or with membrane receptors, that results in membrane permeability and loss of cellular homeostasis, a key event in Alzheimer's disease pathology. Aβ can have an array of impacts on lipid membranes, reports have included: a carpeting effect; a detergent effect; and Aβ ion-channel pore formation. Recent advances imaging these interactions are providing a clearer picture of Aβ induced membrane disruption. Understanding the relationship between different Aβ structures and membrane permeability will inform therapeutics targeting Aβ cytotoxicity.
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Affiliation(s)
- John H. Viles
- Department of Biochemistry, SBBS, Queen MaryUniversity of LondonUK
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2
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Viles JH. Imaging Amyloid-β Membrane Interactions: Ion-Channel Pores and Lipid-Bilayer Permeability in Alzheimer's Disease. Angew Chem Int Ed Engl 2023; 62:e202215785. [PMID: 36876912 PMCID: PMC10953358 DOI: 10.1002/anie.202215785] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/07/2023]
Abstract
The accumulation of the amyloid-β peptides (Aβ) is central to the development of Alzheimer's disease. The mechanism by which Aβ triggers a cascade of events that leads to dementia is a topic of intense investigation. Aβ self-associates into a series of complex assemblies with different structural and biophysical properties. It is the interaction of these oligomeric, protofibril and fibrillar assemblies with lipid membranes, or with membrane receptors, that results in membrane permeability and loss of cellular homeostasis, a key event in Alzheimer's disease pathology. Aβ can have an array of impacts on lipid membranes, reports have included: a carpeting effect; a detergent effect; and Aβ ion-channel pore formation. Recent advances imaging these interactions are providing a clearer picture of Aβ induced membrane disruption. Understanding the relationship between different Aβ structures and membrane permeability will inform therapeutics targeting Aβ cytotoxicity.
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Affiliation(s)
- John H. Viles
- Department of Biochemistry, SBBS, Queen MaryUniversity of LondonUK
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3
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Bulgart HR, Goncalves I, Weisleder N. Leveraging Plasma Membrane Repair Therapeutics for Treating Neurodegenerative Diseases. Cells 2023; 12:1660. [PMID: 37371130 DOI: 10.3390/cells12121660] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 06/12/2023] [Accepted: 06/16/2023] [Indexed: 06/29/2023] Open
Abstract
Plasma membrane repair is an essential cellular mechanism that reseals membrane disruptions after a variety of insults, and compromised repair capacity can contribute to the progression of many diseases. Neurodegenerative diseases are marked by membrane damage from many sources, reduced membrane integrity, elevated intracellular calcium concentrations, enhanced reactive oxygen species production, mitochondrial dysfunction, and widespread neuronal death. While the toxic intracellular effects of these changes in cellular physiology have been defined, the specific mechanism of neuronal death in certain neurodegenerative diseases remains unclear. An abundance of recent evidence indicates that neuronal membrane damage and pore formation in the membrane are key contributors to neurodegenerative disease pathogenesis. In this review, we have outlined evidence supporting the hypothesis that membrane damage is a contributor to neurodegenerative diseases and that therapeutically enhancing membrane repair can potentially combat neuronal death.
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Affiliation(s)
- Hannah R Bulgart
- Department of Physiology & Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Isabella Goncalves
- Department of Physiology & Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Noah Weisleder
- Department of Physiology & Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
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4
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Matthes D, de Groot BL. Molecular dynamics simulations reveal the importance of amyloid-beta oligomer β-sheet edge conformations in membrane permeabilization. J Biol Chem 2023; 299:103034. [PMID: 36806684 PMCID: PMC10033322 DOI: 10.1016/j.jbc.2023.103034] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 02/03/2023] [Accepted: 02/13/2023] [Indexed: 02/18/2023] Open
Abstract
Oligomeric aggregates of the amyloid-beta peptide(1-42) (Aβ42) are regarded as a primary cause of cytotoxicity related to membrane damage in Alzheimer's disease. However, a dynamical and structural characterization of pore-forming Aβ42 oligomers at atomic detail has not been feasible. Here, we used Aβ42 oligomer structures previously determined in a membrane-mimicking environment as putative model systems to study the pore formation process in phospholipid bilayers with all-atom molecular dynamics simulations. Multiple Aβ42 oligomer sizes, conformations, and N-terminally truncated isoforms were investigated on the multi-μs time scale. We found that pore formation and ion permeation occur via edge conductivity and exclusively for β-sandwich structures that feature exposed side-by-side β-strand pairs formed by residues 9 to 21 of Aβ42. The extent of pore formation and ion permeation depends on the insertion depth of hydrophilic residues 13 to 16 (HHQK domain) and thus on subtle differences in the overall stability, orientation, and conformation of the aggregates in the membrane. Additionally, we determined that backbone carbonyl and polar side-chain atoms from the edge strands directly contribute to the coordination sphere of the permeating ions. Furthermore, point mutations that alter the number of favorable side-chain contacts correlate with the ability of the Aβ42 oligomer models to facilitate ion permeation in the bilayer center. Our findings suggest that membrane-inserted, layered β-sheet edges are a key structural motif in pore-forming Aβ42 oligomers independent of their size and play a pivotal role in aggregate-induced membrane permeabilization.
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Affiliation(s)
- Dirk Matthes
- Computational Biomolecular Dynamics Group, Department of Theoretical and Computational Biophysics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
| | - Bert L de Groot
- Computational Biomolecular Dynamics Group, Department of Theoretical and Computational Biophysics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
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5
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Abstract
Perturbation of cell membranes by amyloid β (Ab) peptide oligomers is one possible mechanism of cytotoxicity in Alzheimer's disease, but the structure of such Ab-membrane complexes is unknown. Here we examine the stability of several putative structures by implicit membrane and all-atom molecular dynamics simulations. The structures include (a) a variety of models proposed by other researchers in the past, (b) a heptameric β barrel determined by grafting the Ab sequence onto α-hemolysin, (c) a similar structure with modified strand orientation and turn location based on an experimental β-hairpin structure, (d) oligomers inserting C-terminal β hairpins into one leaflet of the bilayer, (e) oligomers forming parallel C-terminal β barrels, and (f) a helical hexamer made of C-terminal fragments. The α-hemolysin-grafted structure and its alternately oriented variant are stable in the membrane and form an aqueous pore. In contrast, the C-terminal parallel barrels are not stable, presumably due to excessive hydrophobicity of their inner surface. The helical hexamer also failed to stabilize an aqueous pore for the same reason. The C-terminal hairpin-inserting structures remain stably inserted but, again, do not form an aqueous pore. Our results suggest that only β-barrels inserting a combination of C-terminal and other residues can form stable aqueous pores.
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Affiliation(s)
- Aliasghar Sepehri
- Department of Chemistry, City College of New York, CUNY, 160 Convent Avenue, New York, New York10031, United States
| | - Themis Lazaridis
- Department of Chemistry, City College of New York, CUNY, 160 Convent Avenue, New York, New York10031, United States.,Graduate Programs in Chemistry, Biochemistry, and Physics, The Graduate Center, City University of New York, 365 Fifth Avenue, New York, New York10016, United States
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6
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Yavorsky VA, Rozumna NM, Lukyanetz EA. Influence of amyloid beta on impulse spiking of isolated hippocampal neurons. Front Cell Neurosci 2023; 17:1132092. [PMID: 37124394 PMCID: PMC10133472 DOI: 10.3389/fncel.2023.1132092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Accepted: 03/29/2023] [Indexed: 05/02/2023] Open
Abstract
One of the signs of Alzheimer's disease (AD) is the formation of β-amyloid plaques, which ultimately lead to the dysfunction of neurons with subsequent neurodegeneration. Although extensive researches have been conducted on the effects of different amyloid conformations such as oligomers and fibrils on neuronal function in isolated cells and circuits, the exact contribution of extracellular beta-amyloid on neurons remains incompletely comprehended. In our experiments, we studied the effect of β-amyloid peptide (Aβ1-42) on the action potential (APs) generation in isolated CA1 hippocampal neurons in perforated patch clamp conditions. Our findings demonstrate that Aβ1-42 affects the generation of APs differently in various hippocampal neurons, albeit with a shared effect of enhancing the firing response of the neurons within a minute of the start of Aβ1-42 application. In the first response type, there was a shift of 20-65% toward smaller values in the firing threshold of action potentials in response to inward current. Conversely, the firing threshold of action potentials was not affected in the second type of response to the application of Aβ1-42. In these neurons, Aβ1-42 caused a moderate increase in the frequency of spiking, up to 15%, with a relatively uniform increase in the frequency of action potentials generation regardless of the level of input current. Obtained data prove the absence of direct short-term negative effect of the Aβ1-42 on APs generation in neurons. Even with increasing the APs generation frequency and lowering the neurons' activation threshold, neurons were functional. Obtained data can suggest that only the long-acting presence of the Aβ1-42 in the cell environment can cause neuronal dysfunction due to a prolonged increase of APs firing and predisposition to this process.
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7
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Mahakud AK, Shaikh J, Rifa Iqbal VV, Gupta A, Tiwari A, Saleem M. Amyloids on Membrane Interfaces: Implications for Neurodegeneration. J Membr Biol 2022; 255:705-722. [PMID: 35670831 DOI: 10.1007/s00232-022-00245-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 05/12/2022] [Indexed: 12/24/2022]
Abstract
Membrane interfaces are vital for various cellular processes, and their involvement in neurodegenerative disorders such as Alzheimer's and Parkinson's disease has taken precedence in recent years. The amyloidogenic proteins associated with neurodegenerative diseases interact with the neuronal membrane through various means, which has implications for both the onset and progression of the disease. The parameters that regulate the interaction between the membrane and the amyloids remain poorly understood. The review focuses on the various aspects of membrane interactions of amyloids, particularly amyloid-β (Aβ) peptides and Tau involved in Alzheimer's and α-synuclein involved in Parkinson's disease. The genetic, cell biological, biochemical, and biophysical studies that form the basis for our current understanding of the membrane interactions of Aβ peptides, Tau, and α-synuclein are discussed.
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Affiliation(s)
- Amaresh Kumar Mahakud
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India.,Homi Bhabha National Institute, Mumbai, India
| | - Jafarulla Shaikh
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India.,Homi Bhabha National Institute, Mumbai, India
| | - V V Rifa Iqbal
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India.,Homi Bhabha National Institute, Mumbai, India
| | - Abhinav Gupta
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India.,Homi Bhabha National Institute, Mumbai, India
| | - Anuj Tiwari
- Department of Life Sciences, National Institute of Technology, Rourkela, India
| | - Mohammed Saleem
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India. .,Homi Bhabha National Institute, Mumbai, India.
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8
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Durell SR, Kayed R, Guy HR. The amyloid concentric β‐barrel hypothesis: Models of amyloid beta 42 oligomers and annular protofibrils. Proteins 2022; 90:1190-1209. [DOI: 10.1002/prot.26301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 12/31/2021] [Accepted: 01/11/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Stewart R. Durell
- Laboratory of Cell Biology, National Cancer Institute National Institutes of Health Bethesda Maryland USA
| | - Rakez Kayed
- UTMB Mitchell Center for Neurodegenerative Diseases, Department of Neurology University of Texas Medical Branch Galveston Texas USA
| | - H. Robert Guy
- Amyloid Research Consultants (ARC) Cochiti Lake New Mexico USA
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9
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Sun L, Cho HJ, Sen S, Arango AS, Huynh TT, Huang Y, Bandara N, Rogers BE, Tajkhorshid E, Mirica LM. Amphiphilic Distyrylbenzene Derivatives as Potential Therapeutic and Imaging Agents for Soluble and Insoluble Amyloid β Aggregates in Alzheimer's Disease. J Am Chem Soc 2021; 143:10462-10476. [PMID: 34213901 PMCID: PMC8762579 DOI: 10.1021/jacs.1c05470] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Alzheimer's Disease (AD) is the most common neurodegenerative disease, and efficient therapeutic and early diagnostic agents for AD are still lacking. Herein, we report the development of a novel amphiphilic compound, LS-4, generated by linking a hydrophobic amyloid-binding distyrylbenzene fragment with a hydrophilic triazamacrocycle, which dramatically increases the binding affinity toward various amyloid β (Aβ) peptide aggregates, especially for soluble Aβ oligomers. Moreover, upon the administration of LS-4 to 5xFAD mice, fluorescence imaging of LS-4-treated brain sections reveals that LS-4 can penetrate the blood-brain barrier and bind to the Aβ oligomers in vivo. In addition, the treatment of 5xFAD mice with LS-4 reduces the amount of both amyloid plaques and associated phosphorylated tau aggregates vs the vehicle-treated 5xFAD mice, while microglia activation is also reduced. Molecular dynamics simulations corroborate the observation that introducing a hydrophilic moiety into the molecular structure of LS-4 can enhance the electrostatic interactions with the polar residues of the Aβ species. Finally, exploiting the Cu2+-chelating property of the triazamacrocycle, we performed a series of imaging and biodistribution studies that show the 64Cu-LS-4 complex binds to the amyloid plaques and can accumulate to a significantly larger extent in the 5xFAD mouse brains vs the wild-type controls. Overall, these results illustrate that the novel strategy, to employ an amphiphilic molecule containing a hydrophilic moiety attached to a hydrophobic amyloid-binding fragment, can increase the binding affinity for both soluble and insoluble Aβ aggregates and can thus be used to detect and regulate various Aβ species in AD.
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Affiliation(s)
- Liang Sun
- Department of Chemistry, Beckman Institute for Advanced Science and Technology, The Neuroscience Program, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, Illinois 61801, United States
| | - Hong-Jun Cho
- Department of Chemistry, Beckman Institute for Advanced Science and Technology, The Neuroscience Program, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, Illinois 61801, United States
| | - Soumyo Sen
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Center for Biophysics and Quantitative Biology and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Andres S Arango
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Center for Biophysics and Quantitative Biology and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Truc T Huynh
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63108, United States
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States
| | - Yiran Huang
- Department of Chemistry, Beckman Institute for Advanced Science and Technology, The Neuroscience Program, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, Illinois 61801, United States
| | - Nilantha Bandara
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63108, United States
| | - Buck E Rogers
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63108, United States
| | - Emad Tajkhorshid
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Center for Biophysics and Quantitative Biology and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Liviu M Mirica
- Department of Chemistry, Beckman Institute for Advanced Science and Technology, The Neuroscience Program, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, Illinois 61801, United States
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri 63110, United States
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10
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Zaretsky DV, Zaretskaia MV. Mini-review: Amyloid degradation toxicity hypothesis of Alzheimer's disease. Neurosci Lett 2021; 756:135959. [PMID: 34000347 DOI: 10.1016/j.neulet.2021.135959] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 04/28/2021] [Accepted: 05/10/2021] [Indexed: 12/21/2022]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia affecting millions of people. Neuronal death in AD is initiated by oligomeric amyloid-β (Aβ) peptides. The amyloid channel hypothesis readily explains the primary molecular damage but does not address major observations associated with AD such as autophagy failure and decreased metabolism. The amyloid degradation toxicity hypothesis provides the interpretation as a sequence of molecular events. Aβ enters a cell by endocytosis, and the endocytic vesicle is merged with a lysosome. Lysosomal peptidases degrade the peptide. Fragments form membrane channels in lysosomal membranes that have a significant negative charge due to the presence of acidic phospholipids. Amyloid channels can transfer various ions (including protons) and even relatively large compounds, which explains lysosomal permeabilization. The neutralization of lysosomal content inactivates degradation enzymes, results in an accumulation of undigested amyloid, and stalls autophagy. Inadequate quality control of mitochondria is associated with an increased production of reactive oxygen species and decreased energy production. Also, the passage of lysosomal proteases through rare extremely large channels results in cell death. Proposed hypothesis identifies biochemical pathways involved in the initiation and progression of cellular damage induced by beta-amyloid and provides new potential pharmacological targets to treat Alzheimer's disease.
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11
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Yakupova EI, Bobyleva LG, Shumeyko SA, Vikhlyantsev IM, Bobylev AG. Amyloids: The History of Toxicity and Functionality. BIOLOGY 2021; 10:biology10050394. [PMID: 34062910 PMCID: PMC8147320 DOI: 10.3390/biology10050394] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/26/2021] [Accepted: 04/29/2021] [Indexed: 12/15/2022]
Abstract
Proteins can perform their specific function due to their molecular structure. Partial or complete unfolding of the polypeptide chain may lead to the misfolding and aggregation of proteins in turn, resulting in the formation of different structures such as amyloid aggregates. Amyloids are rigid protein aggregates with the cross-β structure, resistant to most solvents and proteases. Because of their resistance to proteolysis, amyloid aggregates formed in the organism accumulate in tissues, promoting the development of various diseases called amyloidosis, for instance Alzheimer's diseases (AD). According to the main hypothesis, it is considered that the cause of AD is the formation and accumulation of amyloid plaques of Aβ. That is why Aβ-amyloid is the most studied representative of amyloids. Therefore, in this review, special attention is paid to the history of Aβ-amyloid toxicity. We note the main problems with anti-amyloid therapy and write about new views on amyloids that can play positive roles in the different organisms including humans.
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Affiliation(s)
- Elmira I. Yakupova
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, 142290 Moscow, Russia; (L.G.B.); (S.A.S.); (I.M.V.); (A.G.B.)
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
- Correspondence: ; Tel.: +7-(985)687-77-27
| | - Liya G. Bobyleva
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, 142290 Moscow, Russia; (L.G.B.); (S.A.S.); (I.M.V.); (A.G.B.)
| | - Sergey A. Shumeyko
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, 142290 Moscow, Russia; (L.G.B.); (S.A.S.); (I.M.V.); (A.G.B.)
| | - Ivan M. Vikhlyantsev
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, 142290 Moscow, Russia; (L.G.B.); (S.A.S.); (I.M.V.); (A.G.B.)
| | - Alexander G. Bobylev
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, 142290 Moscow, Russia; (L.G.B.); (S.A.S.); (I.M.V.); (A.G.B.)
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12
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Abstract
Protein aggregation and amyloid formation are pathogenic events underlying the development of an increasingly large number of human diseases named “proteinopathies”. Abnormal accumulation in affected tissues of amyloid β (Aβ) peptide, islet amyloid polypeptide (IAPP), and the prion protein, to mention a few, are involved in the occurrence of Alzheimer’s (AD), type 2 diabetes mellitus (T2DM) and prion diseases, respectively. Many reports suggest that the toxic properties of amyloid aggregates are correlated with their ability to damage cell membranes. However, the molecular mechanisms causing toxic amyloid/membrane interactions are still far to be completely elucidated. This review aims at describing the mutual relationships linking abnormal protein conformational transition and self-assembly into amyloid aggregates with membrane damage. A cross-correlated analysis of all these closely intertwined factors is thought to provide valuable insights for a comprehensive molecular description of amyloid diseases and, in turn, the design of effective therapies.
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13
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Wang Y, Guo Z, Tan T, Ji Y, Hu J, Zhang Y. The effects of nanobubbles on the assembly of glucagon amyloid fibrils. SOFT MATTER 2021; 17:3486-3493. [PMID: 33657201 DOI: 10.1039/d0sm02279a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Some recent studies have shown that the surface and interface play an important role in the assembly and aggregation of amyloid proteins. However, it is unclear how the gas-liquid interface affects the protein assembly at the nanometer scale although the presence of gas-liquid interfaces is very common in in vitro experiments. Nanobubbles have a large specific surface area, which provides a stage for interactions with various proteins and peptides on the nanometer scale. In this work, nanobubbles produced in solution were employed for studying the effects of the gas-liquid interface on the assembly of glucagon proteins. Atomic force microscopy (AFM) studies showed that nanobubble-treated glucagon solution formed fibrils with an apparent height of 4.02 ± 0.71 nm, in contrast to the fibrils formed with a height of 2.14 ± 0.53 nm in the control. Transmission electron microscopy (TEM) results also showed that nanobubbles promoted the assembly of glucagon to form more fibrils. Thioflavin T (ThT) fluorescence and Fourier transform infrared (FTIR) analyses indicated that the nanobubbles induced the change of the glucagon conformation to a β-sheet structure. A mechanism that explains how nanobubbles affect the assembly of glucagon amyloid fibrils was proposed based on the above-mentioned experimental results. Given the fact that there are a considerable amount of nanobubbles existing in protein solutions, our results indicate that nanobubbles should be considered for fully understanding the protein aggregation events in vitro.
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Affiliation(s)
- Yujiao Wang
- Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
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14
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Zaretsky DV, Zaretskaia M. Degradation Products of Amyloid Protein: Are They The Culprits? Curr Alzheimer Res 2021; 17:869-880. [DOI: 10.2174/1567205017666201203142103] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 10/13/2020] [Accepted: 11/06/2020] [Indexed: 11/22/2022]
Abstract
Objectives:
Beta-amyloid (Aβ) peptides are most toxic to cells in oligomeric form. It is commonly accepted that
oligomers can form ion channels in cell membranes and allow calcium and other ions to enter cells. The activation of other
mechanisms, such as apoptosis or lipid peroxidation, aggravates the toxicity, but it itself can result from the same initial
point, that is, ion disturbance due to an increased permeability of membranes. However, experimental studies of membrane
channels created by Aβ are surprisingly limited. Methods: Here, we report a novel flow cytometry technique which can be
used to detect increased permeability of membranes to calcium induced by the exposure to amyloid peptides. Calcium entry
into the liposome is monitored using calcium-sensitive fluorescent probe. Undamaged lipid membranes are not permeable to
calcium. Liposomes that are prepared in a calcium-free medium become able to accumulate calcium in a calcium-containing
medium only after the formation of channels. Using this technique, we demonstrated that the addition of short amyloid
fragment Aβ, which is known for its extreme toxicity on cultured neurons, readily increased membrane permeability to
calcium. However, neither similarly sized peptide Ab22-35 nor full-length peptide Ab1-42 were producing channels. The
formation of channels was observed in the membranes made of phosphatidylserine, a negatively charged lipid, but not in
membranes made of the neutral phosphatidylcholine.
Methods:
Here, we report a novel flow cytometry technique which can be
used to detect increased permeability of membranes to calcium induced by the exposure to amyloid peptides. Calcium entry
into the liposome is monitored using calcium-sensitive fluorescent probe. Undamaged lipid membranes are not permeable to
calcium. Liposomes that are prepared in a calcium-free medium become able to accumulate calcium in a calcium-containing
medium only after the formation of channels. Using this technique, we demonstrated that the addition of short amyloid
fragment Aβ, which is known for its extreme toxicity on cultured neurons, readily increased membrane permeability to
calcium. However, neither similarly sized peptide Ab22-35 nor full-length peptide Ab1-42 were producing channels. The
formation of channels was observed in the membranes made of phosphatidylserine, a negatively charged lipid, but not in
membranes made of the neutral phosphatidylcholine.
Results:
In the Discussion section, we have analyzed several issues which could be critical for understanding the
pathogenesis of Alzheimer’s disease, specifically 1) the need for a negatively charged membrane to produce the ion channel;
2) the potential role of the aggregated form in cellular toxicity of Ab peptides; 3) channel-forming ability of multiple
degradation products of amyloid; 4) non-specificity of ion channels formed by amyloid peptides. Potential targets of
channel-forming oligomers appear to be intracellular and are organelles well-known for dysfunction in Alzheimer’s disease
(mitochondria and lysosomes). In fact, lysosomes can also be the producers of degraded amyloid. Provided speculations
support the hypothesis that neuronal toxicity can be caused by the degradation products of beta-amyloid.
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15
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Zaretsky DV, Zaretskaia MV. Flow cytometry method to quantify the formation of beta-amyloid membrane ion channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1863:183506. [PMID: 33171157 DOI: 10.1016/j.bbamem.2020.183506] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 10/31/2020] [Accepted: 11/05/2020] [Indexed: 11/17/2022]
Abstract
It is accepted that the cytotoxicity of beta-amyloid is mediated by its oligomers. Amyloid peptides can form ion channels in cell membranes and allow calcium and other ions to enter cells. In this project, we developed a technique to quantify the appearance of calcium in liposomes and applied this technique to study the effect of amyloid peptides on the permeability of membranes. Calcium influx was monitored in liposomes made of phosphatidylcholine (PC) or phosphatidylserine (PS) with an addition of a lipid-soluble dye DiD and containing fluorescent calcium-sensitive probe Fluo-3. The intensity of fluorescence of individual liposomes was measured using a flow cytometer. Calcium ionophore ionomycin served as a positive control. The addition of micromolar concentrations of short fragments of amyloid-beta (Aβ25-35) permeabilized a significant number of PS liposomes. This effect was not observed in PC liposomes. Our data supports the hypothesis that the ion channel formation by amyloid peptide is dependent on electrostatic interactions. High concentrations of Aβ25-35 (above 20 μM) increased signal intensity in a recording channel corresponding to the calcium-sensing probe. However, this phenomenon was also observed in Ca2+-free conditions and even in liposomes without Fluo-3, so we interpreted it as an artifact. Using the described technique, we were not able to detect the formation of calcium channels by several other amyloid peptides. Considering that liposomes appeared resistant to reasonable concentrations of solvents, we expect that described flowmetric technique can be used in high-throughput screening applications.
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16
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Evidence of cadmium and mercury involvement in the Aβ42 aggregation process. Biophys Chem 2020; 266:106453. [DOI: 10.1016/j.bpc.2020.106453] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/30/2020] [Accepted: 08/02/2020] [Indexed: 12/11/2022]
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Puig E, Tolchard J, Riera A, Carulla N. Somatostatin, an In Vivo Binder to Aβ Oligomers, Binds to βPFO Aβ(1-42) Tetramers. ACS Chem Neurosci 2020; 11:3358-3365. [PMID: 32915532 DOI: 10.1021/acschemneuro.0c00470] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Somatostatin (SST14) is strongly related to Alzheimer's disease (AD), as its levels decline during aging, it regulates the proteolytic degradation of the amyloid beta peptide (Aβ), and it binds to Aβ oligomers in vivo. Recently, the 3D structure of a membrane-associated β-sheet pore-forming tetramer (βPFOAβ(1-42) tetramer) has been reported. Here, we show that SST14 binds selectively to the βPFOAβ(1-42) tetramer with a KD value of ∼40 μM without binding to monomeric Aβ(1-42). Specific NMR chemical shift perturbations, observed during titration of SST14, define a binding site in the βPFOAβ(1-42) tetramer and are in agreement with a 2:1 stoichiometry determined by both native mass spectroscopy and isothermal titration calorimetry. These results enabled us to perform driven docking and model the binding mode for the interaction. The present study provides additional evidence on the relation between SST14 and the amyloid cascade and positions the βPFOAβ(1-42) tetramer as a relevant aggregation form of Aβ and as a potential target for AD.
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Affiliation(s)
- Eduard Puig
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, Barcelona 08028, Spain
- CBMN (UMR 5248), University of Bordeaux−CNRS−IPB, Institut Européen de Chimie et Biologie, 2 rue Escarpit, Pessac 33600, France
| | - James Tolchard
- CBMN (UMR 5248), University of Bordeaux−CNRS−IPB, Institut Européen de Chimie et Biologie, 2 rue Escarpit, Pessac 33600, France
| | - Antoni Riera
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, Barcelona 08028, Spain
- Departament de Química Inorgànica i Orgànica, Universitat de Barcelona, Martí i Franqués 1, Barcelona 08028, Spain
| | - Natàlia Carulla
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, Barcelona 08028, Spain
- CBMN (UMR 5248), University of Bordeaux−CNRS−IPB, Institut Européen de Chimie et Biologie, 2 rue Escarpit, Pessac 33600, France
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18
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Ciudad S, Puig E, Botzanowski T, Meigooni M, Arango AS, Do J, Mayzel M, Bayoumi M, Chaignepain S, Maglia G, Cianferani S, Orekhov V, Tajkhorshid E, Bardiaux B, Carulla N. Aβ(1-42) tetramer and octamer structures reveal edge conductivity pores as a mechanism for membrane damage. Nat Commun 2020; 11:3014. [PMID: 32541820 PMCID: PMC7296003 DOI: 10.1038/s41467-020-16566-1] [Citation(s) in RCA: 147] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 05/01/2020] [Indexed: 12/20/2022] Open
Abstract
Formation of amyloid-beta (Aβ) oligomer pores in the membrane of neurons has been proposed to explain neurotoxicity in Alzheimer's disease (AD). Here, we present the three-dimensional structure of an Aβ oligomer formed in a membrane mimicking environment, namely an Aβ(1-42) tetramer, which comprises a six stranded β-sheet core. The two faces of the β-sheet core are hydrophobic and surrounded by the membrane-mimicking environment while the edges are hydrophilic and solvent-exposed. By increasing the concentration of Aβ(1-42) in the sample, Aβ(1-42) octamers are also formed, made by two Aβ(1-42) tetramers facing each other forming a β-sandwich structure. Notably, Aβ(1-42) tetramers and octamers inserted into lipid bilayers as well-defined pores. To establish oligomer structure-membrane activity relationships, molecular dynamics simulations were carried out. These studies revealed a mechanism of membrane disruption in which water permeation occurred through lipid-stabilized pores mediated by the hydrophilic residues located on the core β-sheets edges of the oligomers.
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Affiliation(s)
- Sonia Ciudad
- University of Bordeaux, CBMN (UMR 5248)-CNRS-IPB, Institut Européen de Chimie et Biologie, 2 rue Escarpit, 33600, Pessac, France
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028, Barcelona, Spain
| | - Eduard Puig
- University of Bordeaux, CBMN (UMR 5248)-CNRS-IPB, Institut Européen de Chimie et Biologie, 2 rue Escarpit, 33600, Pessac, France
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028, Barcelona, Spain
- Departament de Química Inorgànica i Orgànica, Universitat de Barcelona, Martí i Franqués 1, 08028, Barcelona, Spain
| | - Thomas Botzanowski
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS UMR7178, IPHC, Strasbourg, France
| | - Moeen Meigooni
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Center for Biophysics and Quantitative Biology and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Andres S Arango
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Center for Biophysics and Quantitative Biology and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Jimmy Do
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Center for Biophysics and Quantitative Biology and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Maxim Mayzel
- Swedish NMR Centre, University of Gothenburg, Box 465, 405 30, Gothenburg, Sweden
| | - Mariam Bayoumi
- Biochemistry, Molecular and Structural Biology Section, University of Leuven, Celestijnenlaan 200G, 3001, Leuven, Belgium
| | - Stéphane Chaignepain
- University of Bordeaux, CBMN (UMR 5248)-CNRS-IPB, Institut Européen de Chimie et Biologie, 2 rue Escarpit, 33600, Pessac, France
| | - Giovanni Maglia
- Groningen Biomolecular Sciences & Biotechnology Institute, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Sarah Cianferani
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS UMR7178, IPHC, Strasbourg, France
| | - Vladislav Orekhov
- Swedish NMR Centre, University of Gothenburg, Box 465, 405 30, Gothenburg, Sweden
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 465, 405 30, Gothenburg, Sweden
| | - Emad Tajkhorshid
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Center for Biophysics and Quantitative Biology and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Benjamin Bardiaux
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, C3BI, Institut Pasteur; CNRS UMR3528; CNRS USR3756, Paris, France
| | - Natàlia Carulla
- University of Bordeaux, CBMN (UMR 5248)-CNRS-IPB, Institut Européen de Chimie et Biologie, 2 rue Escarpit, 33600, Pessac, France.
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028, Barcelona, Spain.
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Karkisaval AG, Rostagno A, Azimov R, Ban DK, Ghiso J, Kagan BL, Lal R. Ion channel formation by N-terminally truncated Aβ (4-42): relevance for the pathogenesis of Alzheimer's disease. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2020; 29:102235. [PMID: 32531337 DOI: 10.1016/j.nano.2020.102235] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 05/27/2020] [Accepted: 05/29/2020] [Indexed: 11/17/2022]
Abstract
Aβ deposition is a pathological hallmark of Alzheimer's disease (AD). Besides the full-length amyloid forming peptides (Aβ1-40 and Aβ1-42), biochemical analyses of brain deposits have identified a variety of N- and C-terminally truncated Aβ variants in sporadic and familial AD patients. However, their relevance for AD pathogenesis remains largely understudied. We demonstrate that Aβ4-42 exhibits a high tendency to form β-sheet structures leading to fast self-aggregation and formation of oligomeric assemblies. Atomic force microscopy and electrophysiological studies reveal that Aβ4-42 forms highly stable ion channels in lipid membranes. These channels that are blocked by monoclonal antibodies specifically recognizing the N-terminus of Aβ4-42. An Aβ variant with a double truncation at phenylalanine-4 and leucine 34, (Aβ4-34), exhibits unstable channel formation capability. Taken together the results presented herein highlight the potential benefit of C-terminal proteolytic cleavage and further support an important pathogenic role for N-truncated Aβ species in AD pathophysiology.
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Affiliation(s)
- Abhijith G Karkisaval
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, 92092, USA
| | - Agueda Rostagno
- Department of Pathology, New York University Grossman School of Medicine, 550 First Avenue, New York, NY, 10016, USA
| | - Rustam Azimov
- Department of Psychiatry, Geffen School of Medicine, University of California, Los Angeles, California 90095, USA; Semel Neuropsychiatric for Neuroscience & Human Behavior, University of California, Los Angeles, California 90095, United States
| | - Deependra K Ban
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, 92092, USA
| | - Jorge Ghiso
- Department of Pathology, New York University Grossman School of Medicine, 550 First Avenue, New York, NY, 10016, USA; Department of Psychiatry, New York University Grossman School of Medicine, 550 First Avenue, New York, NY, 10016, USA.
| | - Bruce L Kagan
- Department of Psychiatry, Geffen School of Medicine, University of California, Los Angeles, California 90095, USA; Semel Neuropsychiatric for Neuroscience & Human Behavior, University of California, Los Angeles, California 90095, United States.
| | - Ratnesh Lal
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, 92092, USA; Department of Bioengineering, University of California San Diego, La Jolla, California, 92092, USA; Materials Science and Engineering, University of California San Diego, La Jolla, California, 92092, USA.
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20
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Younger S, Jang H, Davies HA, Niemiec MJ, Garcia JGN, Nussinov R, Migrino RQ, Madine J, Arce FT. Medin Oligomer Membrane Pore Formation: A Potential Mechanism of Vascular Dysfunction. Biophys J 2020; 118:2769-2782. [PMID: 32402244 PMCID: PMC7264854 DOI: 10.1016/j.bpj.2020.04.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 04/11/2020] [Accepted: 04/17/2020] [Indexed: 12/12/2022] Open
Abstract
Medin, a 50-amino-acid cleavage product of the milk fat globule-EGF factor 8 protein, is one of the most common forms of localized amyloid found in the vasculature of individuals older than 50 years. Medin induces endothelial dysfunction and vascular inflammation, yet despite its prevalence in the human aorta and multiple arterial beds, little is known about the nature of its pathology. Medin oligomers have been implicated in the pathology of aortic aneurysm, aortic dissection, and more recently, vascular dementia. Recent in vitro biomechanical measurements found increased oligomer levels in aneurysm patients with altered aortic wall integrity. Our results suggest an oligomer-mediated toxicity mechanism for medin pathology. Using lipid bilayer electrophysiology, we show that medin oligomers induce ionic membrane permeability by pore formation. Pore activity was primarily observed for preaggregated medin species from the growth-phase and rarely for lag-phase species. Atomic force microscopy (AFM) imaging of medin aggregates at different stages of aggregation revealed the gradual formation of flat domains resembling the morphology of supported lipid bilayers. Transmission electron microscopy images showed the coexistence of compact oligomers, largely consistent with the AFM data, and larger protofibrillar structures. Circular dichroism spectroscopy revealed the presence of largely disordered species and suggested the presence of β-sheets. This observation and the significantly lower thioflavin T fluorescence emitted by medin aggregates compared to amyloid-β fibrils, along with the absence of amyloid fibers in the AFM and transmission electron microscopy images, suggest that medin aggregation into pores follows a nonamyloidogenic pathway. In silico modeling by molecular dynamics simulations provides atomic-level structural detail of medin pores with the CNpNC barrel topology and diameters comparable to values estimated from experimental pore conductances.
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Affiliation(s)
- Scott Younger
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona
| | - Hyunbum Jang
- Computational Structural Biology Section, Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - Hannah A Davies
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Martin J Niemiec
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona
| | - Joe G N Garcia
- Department of Medicine, University of Arizona, Tucson, Arizona
| | - Ruth Nussinov
- Computational Structural Biology Section, Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland; Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Raymond Q Migrino
- Office of Research, Phoenix Veterans Affairs Health Care System, Phoenix, Arizona; Department of Medicine, University of Arizona College of Medicine-Phoenix, Arizona
| | - Jillian Madine
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Fernando T Arce
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona; Department of Medicine, University of Arizona, Tucson, Arizona.
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21
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Efimova SS, Ostroumova OS. Mechanisms of Regulation of Amyloid-Induced Permeability of Model Lipid Membranes by Polyphenols. ACTA ACUST UNITED AC 2019. [DOI: 10.1134/s1990519x19040023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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22
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Yap T, Shamsher E, Guo L, Cordeiro M. Ophthalmic Research Lecture 2018: DARC as a Potential Surrogate Marker. Ophthalmic Res 2019; 63:1-7. [DOI: 10.1159/000500527] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 11/19/2022]
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23
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Serra-Batiste M, Ninot-Pedrosa M, Puig E, Ciudad S, Gairí M, Carulla N. Preparation of a Well-Defined and Stable β-Barrel Pore-Forming Aβ42 Oligomer. Methods Mol Biol 2019; 1779:13-22. [PMID: 29886524 DOI: 10.1007/978-1-4939-7816-8_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The formation of amyloid-β peptide (Aβ) oligomers at the cellular membrane is considered a crucial process that underlies neurotoxicity in Alzheimer's disease (AD). To obtain structural information on this type of oligomers, we were inspired by membrane protein approaches used to stabilize, characterize, and analyze the function of such proteins. Using these approaches, we developed conditions under which Aβ42, the Aβ variant most strongly linked to the aetiology of AD, assembles into an oligomer that inserts into lipid bilayers as a well-defined pore and adopts a specific structure with characteristics of a β-barrel arrangement. We named this oligomer β-barrel Pore-Forming Aβ42 Oligomer (βPFOAβ42). Here, we describe detailed protocols for its preparation and characterization. We expect βPFOAβ42 to be useful in establishing the involvement of membrane-associated Aβ oligomers in AD.
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Affiliation(s)
- Montserrat Serra-Batiste
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute Science and Technology, Barcelona, Spain
| | - Martí Ninot-Pedrosa
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute Science and Technology, Barcelona, Spain.,CBMN (UMR 5248), University of Bordeaux-CNRS-IPB, Institut Européen de Chimie et Biologie, Pessac, France
| | - Eduard Puig
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute Science and Technology, Barcelona, Spain.,CBMN (UMR 5248), University of Bordeaux-CNRS-IPB, Institut Européen de Chimie et Biologie, Pessac, France
| | - Sonia Ciudad
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute Science and Technology, Barcelona, Spain.,CBMN (UMR 5248), University of Bordeaux-CNRS-IPB, Institut Européen de Chimie et Biologie, Pessac, France
| | - Margarida Gairí
- NMR Facility, Scientific and Technological Centers, University of Barcelona (CCiTUB), Barcelona, Spain
| | - Natàlia Carulla
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute Science and Technology, Barcelona, Spain. .,CBMN (UMR 5248), University of Bordeaux-CNRS-IPB, Institut Européen de Chimie et Biologie, Pessac, France.
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24
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Concentration-dependent effects of mercury and lead on Aβ42: possible implications for Alzheimer's disease. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2019; 48:173-187. [PMID: 30603762 DOI: 10.1007/s00249-018-1344-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 09/24/2018] [Accepted: 12/10/2018] [Indexed: 02/06/2023]
Abstract
Mercury (Hg) and lead (Pb) are known to be toxic non-radioactive elements, with well-described neurotoxicology. Much evidence supports the implication of metals as potential risk cofactors in Alzheimer's disease (AD). Although the action mechanism of the two metals remains unclear, Hg and Pb toxicity in AD could depend on their ability to favour misfolding and aggregation of amyloid beta proteins (Aβs) that seem to have toxic properties, particularly in their aggregated state. In our study, we evaluated the effect of Hg and Pb both on the Aβ42 ion channel incorporated in a planar lipid membrane made up of phosphatidylcholine containing 30% cholesterol and on the secondary structure of Aβ42 in an aqueous environment. The effects of Hg and Pb on the Aβ42 peptide were observed for its channel incorporated into a membrane as well as for the peptide in solution. A decreasing Aβ42 channel frequency and the formation of large and amorphous aggregates in solution that are prone to precipitate were both dependent on metal concentration. These experimental data suggest that Hg and Pb interact directly with Aβs, strengthening the hypothesis that the two metals may be a risk factor in AD.
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Julien C, Tomberlin C, Roberts CM, Akram A, Stein GH, Silverman MA, Link CD. In vivo induction of membrane damage by β-amyloid peptide oligomers. Acta Neuropathol Commun 2018; 6:131. [PMID: 30497524 PMCID: PMC6263551 DOI: 10.1186/s40478-018-0634-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 11/13/2018] [Indexed: 01/17/2023] Open
Abstract
Exposure to the β-amyloid peptide (Aβ) is toxic to neurons and other cell types, but the mechanism(s) involved are still unresolved. Synthetic Aβ oligomers can induce ion-permeable pores in synthetic membranes, but whether this ability to damage membranes plays a role in the ability of Aβ oligomers to induce tau hyperphosphorylation, or other disease-relevant pathological changes, is unclear. To examine the cellular responses to Aβ exposure independent of possible receptor interactions, we have developed an in vivo C. elegans model that allows us to visualize these cellular responses in living animals. We find that feeding C. elegans E. coli expressing human Aβ induces a membrane repair response similar to that induced by exposure to the CRY5B, a known pore-forming toxin produced by B. thuringensis. This repair response does not occur when C. elegans is exposed to an Aβ Gly37Leu variant, which we have previously shown to be incapable of inducing tau phosphorylation in hippocampal neurons. The repair response is also blocked by loss of calpain function, and is altered by loss-of-function mutations in the C. elegans orthologs of BIN1 and PICALM, well-established risk genes for late onset Alzheimer's disease. To investigate the role of membrane repair on tau phosphorylation directly, we exposed hippocampal neurons to streptolysin O (SLO), a pore-forming toxin that induces a well-characterized membrane repair response. We find that SLO induces tau hyperphosphorylation, which is blocked by calpain inhibition. Finally, we use a novel biarsenical dye-tagging approach to show that the Gly37Leu substitution interferes with Aβ multimerization and thus the formation of potentially pore-forming oligomers. We propose that Aβ-induced tau hyperphosphorylation may be a downstream consequence of induction of a membrane repair process.
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Zhang L, Zhang L, Hu Q, Wei J, Wang N, Di D, Pei D, Liu Y. Establishment and application of a method for screening the therapeutic drugs of ethanol-induced liver injury based on cellular metabonomics. Biomed Chromatogr 2018; 32:e4369. [DOI: 10.1002/bmc.4369] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 07/29/2018] [Accepted: 08/13/2018] [Indexed: 12/25/2022]
Affiliation(s)
- Linghao Zhang
- Institute of Nutrition and Food Hygiene, School of Public Health; Lanzhou University; Lanzhou China
- Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province; Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences; Lanzhou China
- Center of Resource Chemical & New Material, Qingdao; Qingdao China
| | - Lina Zhang
- Institute of Nutrition and Food Hygiene, School of Public Health; Lanzhou University; Lanzhou China
- Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province; Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences; Lanzhou China
- Center of Resource Chemical & New Material, Qingdao; Qingdao China
| | - Qingping Hu
- Institute of Nutrition and Food Hygiene, School of Public Health; Lanzhou University; Lanzhou China
- Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province; Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences; Lanzhou China
- Center of Resource Chemical & New Material, Qingdao; Qingdao China
| | - Jianteng Wei
- Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province; Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences; Lanzhou China
- Center of Resource Chemical & New Material, Qingdao; Qingdao China
| | - Ningli Wang
- Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province; Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences; Lanzhou China
- Center of Resource Chemical & New Material, Qingdao; Qingdao China
| | - Duolong Di
- Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province; Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences; Lanzhou China
- Center of Resource Chemical & New Material, Qingdao; Qingdao China
| | - Dong Pei
- Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province; Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences; Lanzhou China
- Center of Resource Chemical & New Material, Qingdao; Qingdao China
| | - Yewei Liu
- Institute of Nutrition and Food Hygiene, School of Public Health; Lanzhou University; Lanzhou China
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27
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Serra-Batiste M, Tolchard J, Giusti F, Zoonens M, Carulla N. Stabilization of a Membrane-Associated Amyloid-β Oligomer for Its Validation in Alzheimer's Disease. Front Mol Biosci 2018; 5:38. [PMID: 29725595 PMCID: PMC5917194 DOI: 10.3389/fmolb.2018.00038] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 03/28/2018] [Indexed: 11/13/2022] Open
Abstract
We have recently reported on the preparation of a membrane-associated β-barrel Pore-Forming Aβ42 Oligomer (βPFOAβ42). It corresponds to a stable and homogeneous Aβ42 oligomer that inserts into lipid bilayers as a well-defined pore and adopts a specific structure with characteristics of a β-barrel arrangement. As a follow-up of this work, we aim to establish βPFOAβ42's relevance in Alzheimer's disease (AD). However, βPFOAβ42 is formed under dodecyl phosphocholine (DPC) micelle conditions-intended to mimic the hydrophobic environment of membranes-which are dynamic. Consequently, dilution of the βPFOAβ42/DPC complex in a detergent-free buffer leads to dispersion of the DPC molecules from the oligomer surface, leaving the oligomer without the hydrophobic micelle belt that stabilizes it. Since dilution is required for any biological test, transfer of βPFOAβ42 from DPC micelles into another hydrophobic biomimetic membrane environment, that remains associated with βPFOAβ42 even under high dilution conditions, is a requisite for the validation of βPFOAβ42 in AD. Here we describe conditions for exchanging DPC micelles with amphipols (APols), which are amphipathic polymers designed to stabilize membrane proteins in aqueous solutions. APols bind in an irreversible but non-covalent manner to the hydrophobic surface of membrane proteins preserving their structure even under extreme dilution conditions. We tested three types of APols with distinct physical-chemical properties and found that the βPFOAβ42/DPC complex can only be trapped in non-ionic APols (NAPols). The characterization of the resulting βPFOAβ42/NAPol complex by biochemical tools and structural biology techniques allowed us to establish that the oligomer structure is maintained even under high dilution. Based on these findings, this work constitutes a first step towards the in vivo validation of βPFOAβ42 in AD.
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Affiliation(s)
- Montserrat Serra-Batiste
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute Science and Technology (BIST), Barcelona, Spain
| | - James Tolchard
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute Science and Technology (BIST), Barcelona, Spain.,CBMN (UMR 5248), Centre National de la Recherche Scientifique - IPB, Institut Européen de Chimie et Biologie, University of Bordeaux, Pessac, France
| | - Fabrice Giusti
- Laboratoire de Physico-Chimie Moléculaire des Protéines Membranaires (UMR 7099), Université Paris-7 - Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, Paris, France
| | - Manuela Zoonens
- Laboratoire de Physico-Chimie Moléculaire des Protéines Membranaires (UMR 7099), Université Paris-7 - Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, Paris, France
| | - Natàlia Carulla
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute Science and Technology (BIST), Barcelona, Spain.,CBMN (UMR 5248), Centre National de la Recherche Scientifique - IPB, Institut Européen de Chimie et Biologie, University of Bordeaux, Pessac, France
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28
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Abstract
Glaucoma is one of the leading causes of irreversible visual loss, which has been estimated to affect 3.5% of those over 40 years old and projected to affect a total of 112 million people by 2040. Such a dramatic increase in affected patients demonstrates the need for continual improvement in the way we diagnose and treat this condition. Annexin A5 is a 36 kDa protein that is ubiquitously expressed in humans and is studied as an indicator of apoptosis in several fields. This molecule has a high calcium-dependent affinity for phosphatidylserine, a cell membrane phospholipid externalized to the outer cell membrane in early apoptosis. The DARC (Detection of Apoptosing Retinal Cells) project uses fluorescently-labelled annexin A5 to assess glaucomatous degeneration, the inherent process of which is the apoptosis of retinal ganglion cells. Furthermore, this project has conducted investigation of the retinal apoptosis in the neurodegenerative conditions of the eye and brain. In this present study, we summarized the use of annexin A5 as a marker of apoptosis in the eye. We also relayed the progress of the DARC project, developing real-time imaging of retinal ganglion cell apoptosis in vivo from the experimental models of disease and identifying mechanisms underlying neurodegeneration and its treatments, which has been applied to the first human clinical trials. DARC has potential as a biomarker in neurodegeneration, especially in the research of novel treatments, and could be a useful tool for the diagnosis and monitoring of glaucoma.
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Amyloid growth and membrane damage: Current themes and emerging perspectives from theory and experiments on Aβ and hIAPP. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1625-1638. [PMID: 29501606 DOI: 10.1016/j.bbamem.2018.02.022] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/21/2018] [Accepted: 02/21/2018] [Indexed: 12/15/2022]
Abstract
Alzheimer's Disease (AD) and Type 2 diabetes mellitus (T2DM) are two incurable diseases both hallmarked by an abnormal deposition of the amyloidogenic peptides Aβ and Islet Amyloid Polypeptide (IAPP) in affected tissues. Epidemiological data demonstrate that patients suffering from diabetes are at high risk of developing AD, thus making the search for factors common to the two pathologies of special interest for the design of new therapies. Accumulating evidence suggests that the toxic properties of both Aβ or IAPP are ascribable to their ability to damage the cell membrane. However, the molecular details describing Aβ or IAPP interaction with membranes are poorly understood. This review focuses on biophysical and in silico studies addressing these topics. Effects of calcium, cholesterol and membrane lipid composition in driving aberrant Aβ or IAPP interaction with the membrane will be specifically considered. The cross correlation of all these factors appears to be a key issue not only to shed light in the countless and often controversial reports relative to this area but also to gain valuable insights into the central events leading to membrane damage caused by amyloidogenic peptides. 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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30
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Lee J, Kim YH, T Arce F, Gillman AL, Jang H, Kagan BL, Nussinov R, Yang J, Lal R. Amyloid β Ion Channels in a Membrane Comprising Brain Total Lipid Extracts. ACS Chem Neurosci 2017; 8:1348-1357. [PMID: 28135799 PMCID: PMC6197823 DOI: 10.1021/acschemneuro.7b00006] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Amyloid β (Aβ) oligomers are the predominant toxic species in the pathology of Alzheimer's disease. The prevailing mechanism for toxicity by Aβ oligomers includes ionic homeostasis destabilization in neuronal cells by forming ion channels. These channel structures have been previously studied in model lipid bilayers. In order to gain further insight into the interaction of Aβ oligomers with natural membrane compositions, we have examined the structures and conductivities of Aβ oligomers in a membrane composed of brain total lipid extract (BTLE). We utilized two complementary techniques: atomic force microscopy (AFM) and black lipid membrane (BLM) electrical recording. Our results indicate that Aβ1-42 forms ion channel structures in BTLE membranes, accompanied by a heterogeneous population of ionic current fluctuations. Notably, the observed current events generated by Aβ1-42 peptides in BTLE membranes possess different characteristics compared to current events generated by the presence of Aβ1-42 in model membranes comprising a 1:1 mixture of DOPS and POPE lipids. Oligomers of the truncated Aβ fragment Aβ17-42 (p3) exhibited similar ion conductivity behavior as Aβ1-42 in BTLE membranes. However, the observed macroscopic ion flux across the BTLE membranes induced by Aβ1-42 pores was larger than for p3 pores. Our analysis of structure and conductance of oligomeric Aβ pores in a natural lipid membrane closely mimics the in vivo cellular environment suggesting that Aβ pores could potentially accelerate the loss of ionic homeostasis and cellular abnormalities. Hence, these pore structures may serve as a target for drug development and therapeutic strategies for AD treatment.
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Affiliation(s)
| | | | - Fernando T Arce
- Division of Translational and Regenerative Medicine, Department of Medicine, Department of Biomedical Engineering, University of Arizona , Tucson, Arizona 85721, United States
| | | | - Hyunbum Jang
- Cancer and Inflammation Program, National Cancer Institute at Frederick, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
| | - Bruce L Kagan
- Department of Psychiatry, David Geffen School of Medicine, Semel Institute for Neuroscience and Human Behavior, University of California , Los Angeles, California 90024, United States
| | - Ruth Nussinov
- Cancer and Inflammation Program, National Cancer Institute at Frederick, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
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31
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Bode DC, Baker MD, Viles JH. Ion Channel Formation by Amyloid-β42 Oligomers but Not Amyloid-β40 in Cellular Membranes. J Biol Chem 2016; 292:1404-1413. [PMID: 27927987 DOI: 10.1074/jbc.m116.762526] [Citation(s) in RCA: 149] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 11/24/2016] [Indexed: 12/23/2022] Open
Abstract
A central hallmark of Alzheimer's disease is the presence of extracellular amyloid plaques chiefly consisting of amyloid-β (Aβ) peptides in the brain interstitium. Aβ largely exists in two isoforms, 40 and 42 amino acids long, but a large body of evidence points to Aβ(1-42) rather than Aβ(1-40) as the cytotoxic form. One proposed mechanism by which Aβ exerts toxicity is the formation of ion channel pores that disrupt intracellular Ca2+ homeostasis. However, previous studies using membrane mimetics have not identified any notable difference in the channel forming properties between Aβ(1-40) and Aβ(1-42). Here, we tested whether a more physiological environment, membranes excised from HEK293 cells of neuronal origin, would reveal differences in the relative channel forming ability of monomeric, oligomeric, and fibrillar forms of both Aβ(1-40) and Aβ(1-42). Aβ preparations were characterized with transmission electron microscopy and thioflavin T fluorescence. Aβ was then exposed to the extracellular face of excised membranes, and transmembrane currents were monitored using patch clamp. Our data indicated that Aβ(1-42) assemblies in oligomeric preparations form voltage-independent, non-selective ion channels. In contrast, Aβ(1-40) oligomers, fibers, and monomers did not form channels. Ion channel conductance results suggested that Aβ(1-42) oligomers, but not monomers and fibers, formed three distinct pore structures with 1.7-, 2.1-, and 2.4-nm pore diameters. Our findings demonstrate that only Aβ(1-42) contains unique structural features that facilitate membrane insertion and channel formation, now aligning ion channel formation with the differential neurotoxic effect of Aβ(1-40) and Aβ(1-42) in Alzheimer's disease.
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Affiliation(s)
- David C Bode
- From the School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom and
| | - Mark D Baker
- the Blizard Institute, Centre for Neuroscience and Trauma, Barts and The London School of Medicine and Dentistry, Queen Mary, University of London, 4 Newark Street, London E1 2AT, United Kingdom
| | - John H Viles
- From the School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom and
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32
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Aβ42 assembles into specific β-barrel pore-forming oligomers in membrane-mimicking environments. Proc Natl Acad Sci U S A 2016; 113:10866-71. [PMID: 27621459 DOI: 10.1073/pnas.1605104113] [Citation(s) in RCA: 207] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The formation of amyloid-β peptide (Aβ) oligomers at the cellular membrane is considered to be a crucial process underlying neurotoxicity in Alzheimer's disease (AD). Therefore, it is critical to characterize the oligomers that form within a membrane environment. To contribute to this characterization, we have applied strategies widely used to examine the structure of membrane proteins to study the two major Aβ variants, Aβ40 and Aβ42. Accordingly, various types of detergent micelles were extensively screened to identify one that preserved the properties of Aβ in lipid environments-namely the formation of oligomers that function as pores. Remarkably, under the optimized detergent micelle conditions, Aβ40 and Aβ42 showed different behavior. Aβ40 aggregated into amyloid fibrils, whereas Aβ42 assembled into oligomers that inserted into lipid bilayers as well-defined pores and adopted a specific structure with characteristics of a β-barrel arrangement that we named β-barrel pore-forming Aβ42 oligomers (βPFOsAβ42). Because Aβ42, relative to Aβ40, has a more prominent role in AD, the higher propensity of Aβ42 to form βPFOs constitutes an indication of their relevance in AD. Moreover, because βPFOsAβ42 adopt a specific structure, this property offers an unprecedented opportunity for testing a hypothesis regarding the involvement of βPFOs and, more generally, membrane-associated Aβ oligomers in AD.
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33
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Ullah G, Demuro A, Parker I, Pearson JE. Analyzing and Modeling the Kinetics of Amyloid Beta Pores Associated with Alzheimer's Disease Pathology. PLoS One 2015; 10:e0137357. [PMID: 26348728 PMCID: PMC4562663 DOI: 10.1371/journal.pone.0137357] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 08/14/2015] [Indexed: 11/24/2022] Open
Abstract
Amyloid beta (Aβ) oligomers associated with Alzheimer’s disease (AD) form Ca2+-permeable plasma membrane pores, leading to a disruption of the otherwise well-controlled intracellular calcium (Ca2+) homeostasis. The resultant up-regulation of intracellular Ca2+ concentration has detrimental implications for memory formation and cell survival. The gating kinetics and Ca2+ permeability of Aβ pores are not well understood. We have used computational modeling in conjunction with the ability of optical patch-clamping for massively parallel imaging of Ca2+ flux through thousands of pores in the cell membrane of Xenopus oocytes to elucidate the kinetic properties of Aβ pores. The fluorescence time-series data from individual pores were idealized and used to develop data-driven Markov chain models for the kinetics of the Aβ pore at different stages of its evolution. Our study provides the first demonstration of developing Markov chain models for ion channel gating that are driven by optical-patch clamp data with the advantage of experiments being performed under close to physiological conditions. Towards the end, we demonstrate the up-regulation of gating of various Ca2+ release channels due to Aβ pores and show that the extent and spatial range of such up-regulation increases as Aβ pores with low open probability and Ca2+ permeability transition into those with high open probability and Ca2+ permeability.
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Affiliation(s)
- Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America
- * E-mail:
| | - Angelo Demuro
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA 92697, United States of America
| | - Ian Parker
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA 92697, United States of America
| | - John E. Pearson
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, NM 87545, United States of America
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34
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Efimova SS, Zakharov VV, Ostroumova OS. Effects of dipole modifiers on channel-forming activity of amyloid and amyloid-like peptides in lipid bilayers. ACTA ACUST UNITED AC 2015. [DOI: 10.1134/s1990519x15030049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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35
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36
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Jang H, Arce FT, Ramachandran S, Kagan BL, Lal R, Nussinov R. Disordered amyloidogenic peptides may insert into the membrane and assemble into common cyclic structural motifs. Chem Soc Rev 2014; 43:6750-64. [PMID: 24566672 PMCID: PMC4143503 DOI: 10.1039/c3cs60459d] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Aggregation of disordered amyloidogenic peptides into oligomers is the causative agent of amyloid-related diseases. In solution, disordered protein states are characterized by heterogeneous ensembles. Among these, β-rich conformers self-assemble via a conformational selection mechanism to form energetically-favored cross-β structures, regardless of their precise sequences. These disordered peptides can also penetrate the membrane, and electrophysiological data indicate that they form ion-conducting channels. Based on these and additional data, including imaging and molecular dynamics simulations of a range of amyloid peptides, Alzheimer's amyloid-β (Aβ) peptide, its disease-related variants with point mutations and N-terminal truncated species, other amyloidogenic peptides, as well as a cytolytic peptide and a synthetic gel-forming peptide, we suggest that disordered amyloidogenic peptides can also present a common motif in the membrane. The motif consists of curved, moon-like β-rich oligomers associated into annular organizations. The motif is favored in the lipid bilayer since it permits hydrophobic side chains to face and interact with the membrane and the charged/polar residues to face the solvated channel pores. Such channels are toxic since their pores allow uncontrolled leakage of ions into/out of the cell, destabilizing cellular ionic homeostasis. Here we detail Aβ, whose aggregation is associated with Alzheimer's disease (AD) and for which there are the most abundant data. AD is a protein misfolding disease characterized by a build-up of Aβ peptide as senile plaques, neurodegeneration, and memory loss. Excessively produced Aβ peptides may directly induce cellular toxicity, even without the involvement of membrane receptors through Aβ peptide-plasma membrane interactions.
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Affiliation(s)
- Hyunbum Jang
- Cancer and Inflammation Program, National Cancer Institute at Frederick, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, U.S.A
| | - Fernando Teran Arce
- Departments of Bioengineering and of Mechanical and Aerospace Engineering, and Materials Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Srinivasan Ramachandran
- Departments of Bioengineering and of Mechanical and Aerospace Engineering, and Materials Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Bruce L. Kagan
- Department of Psychiatry, David Geffen School of Medicine, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, California 90024, U.S.A
| | - Ratnesh Lal
- Departments of Bioengineering and of Mechanical and Aerospace Engineering, and Materials Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Ruth Nussinov
- Cancer and Inflammation Program, National Cancer Institute at Frederick, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, U.S.A
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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37
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Notarachille G, Arnesano F, Calò V, Meleleo D. Heavy metals toxicity: effect of cadmium ions on amyloid beta protein 1-42. Possible implications for Alzheimer's disease. Biometals 2014; 27:371-88. [PMID: 24557150 DOI: 10.1007/s10534-014-9719-6] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 02/12/2014] [Indexed: 02/02/2023]
Abstract
Cadmium (Cd) is an environmental contaminant, highly toxic to humans. This biologically non-essential element accumulates in the body, especially in the kidney, liver, lung and brain and can induce several toxic effects, depending on the concentration and the exposure time. Cd has been linked to Alzheimer's disease (AD) as a probable risk factor, as it shows higher concentrations in brain tissues of AD patients than in healthy people, its implication in the formation of neurofibrillary tangles and in the aggregation process of amyloid beta peptides (AβPs). AβPs seem to have toxic properties, particularly in their aggregated state; insoluble AβP forms, such as small and large aggregates, protofibrils and fibrils, appear to be implicated in the pathogenesis of AD. In our study, we have evaluated the effect of Cd, at different concentrations, both on the AβP1-42 ion channel incorporated in a planar lipid membrane made up of phosphatidylcholine containing 30 % cholesterol and on the secondary structure of AβP1-42 in aqueous environment. Cadmium is able to interact with the AβP1-42 peptide by acting on the channel incorporated into the membrane as well as on the peptide in solution, both decreasing AβP1-42 channel frequency and in solution forming large and amorphous aggregates prone to precipitate. These experimental observations suggesting a toxic role for Cd strengthen the hypothesis that Cd may interact directly with AβPs and may be a risk factor in AD.
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Affiliation(s)
- Gabriella Notarachille
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", via E. Orabona 4, 70126, Bari, Italy
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38
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Hayden EY, Teplow DB. Amyloid β-protein oligomers and Alzheimer's disease. ALZHEIMERS RESEARCH & THERAPY 2013; 5:60. [PMID: 24289820 PMCID: PMC3978746 DOI: 10.1186/alzrt226] [Citation(s) in RCA: 192] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The oligomer cascade hypothesis, which states that oligomers are the initiating pathologic agents in Alzheimer’s disease, has all but supplanted the amyloid cascade hypothesis, which suggested that fibers were the key etiologic agents in Alzheimer’s disease. We review here the results of in vivo, in vitro and in silico studies of amyloid β-protein oligomers, and discuss important caveats that should be considered in the evaluation of these results. This article is divided into four sections that mirror the main approaches used in the field to better understand oligomers: (1) attempts to locate and examine oligomers in vivo in situ; that is, without removing these species from their environment; (2) studies involving oligomers extracted from human or animal tissues and the subsequent characterization of their properties ex vivo; (3) studies of oligomers that have been produced synthetically and studied using a reductionist approach in relatively simple in vitro biophysical systems; and (4) computational studies of oligomers in silico. These multiple orthogonal approaches have revealed much about the molecular and cell biology of amyloid β-protein. However, as informative as these approaches have been, the amyloid β-protein oligomer system remains enigmatic.
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Affiliation(s)
- Eric Y Hayden
- Department of Neurology, 635 Charles E. Young Drive South, Room 455, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - David B Teplow
- Department of Neurology, 635 Charles E. Young Drive South, Room 455, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA ; Brain Research and Molecular Biology Institutes, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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39
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AβP1-42 incorporation and channel formation in planar lipid membranes: the role of cholesterol and its oxidation products. J Bioenerg Biomembr 2013; 45:369-81. [DOI: 10.1007/s10863-013-9513-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 04/12/2013] [Indexed: 02/06/2023]
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40
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Poojari C, Kukol A, Strodel B. How the amyloid-β peptide and membranes affect each other: An extensive simulation study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:327-39. [DOI: 10.1016/j.bbamem.2012.09.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 09/03/2012] [Accepted: 09/04/2012] [Indexed: 11/24/2022]
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41
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Two-step mechanism of membrane disruption by Aβ through membrane fragmentation and pore formation. Biophys J 2013; 103:702-10. [PMID: 22947931 DOI: 10.1016/j.bpj.2012.06.045] [Citation(s) in RCA: 310] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 06/11/2012] [Accepted: 06/18/2012] [Indexed: 12/25/2022] Open
Abstract
Disruption of cell membranes by Aβ is believed to be one of the key components of Aβ toxicity. However, the mechanism by which this occurs is not fully understood. Here, we demonstrate that membrane disruption by Aβ occurs by a two-step process, with the initial formation of ion-selective pores followed by nonspecific fragmentation of the lipid membrane during amyloid fiber formation. Immediately after the addition of freshly dissolved Aβ(1-40), defects form on the membrane that share many of the properties of Aβ channels originally reported from single-channel electrical recording, such as cation selectivity and the ability to be blockaded by zinc. By contrast, subsequent amyloid fiber formation on the surface of the membrane fragments the membrane in a way that is not cation selective and cannot be stopped by zinc ions. Moreover, we observed that the presence of ganglioside enhances both the initial pore formation and the fiber-dependent membrane fragmentation process. Whereas pore formation by freshly dissolved Aβ(1-40) is weakly observed in the absence of gangliosides, fiber-dependent membrane fragmentation can only be observed in their presence. These results provide insights into the toxicity of Aβ and may aid in the design of specific compounds to alleviate the neurodegeneration of Alzheimer's disease.
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42
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Hamley IW. The Amyloid Beta Peptide: A Chemist’s Perspective. Role in Alzheimer’s and Fibrillization. Chem Rev 2012; 112:5147-92. [DOI: 10.1021/cr3000994] [Citation(s) in RCA: 670] [Impact Index Per Article: 55.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- I. W. Hamley
- Department
of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD,
U.K
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43
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Kagan BL, Jang H, Capone R, Arce FT, Ramachandran S, Lal R, Nussinov R. Antimicrobial properties of amyloid peptides. Mol Pharm 2012; 9:708-17. [PMID: 22081976 PMCID: PMC3297685 DOI: 10.1021/mp200419b] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
More than two dozen clinical syndromes known as amyloid diseases are characterized by the buildup of extended insoluble fibrillar deposits in tissues. These amorphous Congo red staining deposits known as amyloids exhibit a characteristic green birefringence and cross-β structure. Substantial evidence implicates oligomeric intermediates of amyloids as toxic species in the pathogenesis of these chronic disease states. A growing body of data has suggested that these toxic species form ion channels in cellular membranes causing disruption of calcium homeostasis, membrane depolarization, energy drainage, and in some cases apoptosis. Amyloid peptide channels exhibit a number of common biological properties including the universal U-shape β-strand-turn-β-strand structure, irreversible and spontaneous insertion into membranes, production of large heterogeneous single-channel conductances, relatively poor ion selectivity, inhibition by Congo red, and channel blockade by zinc. Recent evidence has suggested that increased amounts of amyloids not only are toxic to its host target cells but also possess antimicrobial activity. Furthermore, at least one human antimicrobial peptide, protegrin-1, which kills microbes by a channel-forming mechanism, has been shown to possess the ability to form extended amyloid fibrils very similar to those of classic disease-forming amyloids. In this paper, we will review the reported antimicrobial properties of amyloids and the implications of these discoveries for our understanding of amyloid structure and function.
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Affiliation(s)
- Bruce L. Kagan
- Department of Psychiatry, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California, Los Angeles, California 90024, U.S.A
| | - Hyunbum Jang
- Center for Cancer Research Nanobiology Program, SAIC-Frederick, Inc., NCI-Frederick, Frederick, Maryland 21702, U.S.A
| | - Ricardo Capone
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Fernando Teran Arce
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Srinivasan Ramachandran
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Ratnesh Lal
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Ruth Nussinov
- Center for Cancer Research Nanobiology Program, SAIC-Frederick, Inc., NCI-Frederick, Frederick, Maryland 21702, U.S.A
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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44
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Capone R, Jang H, Kotler SA, Connelly L, Teran Arce F, Ramachandran S, Kagan BL, Nussinov R, Lal R. All-d-Enantiomer of β-Amyloid Peptide Forms Ion Channels in Lipid Bilayers. J Chem Theory Comput 2012; 8:1143-1152. [PMID: 22423218 PMCID: PMC3302213 DOI: 10.1021/ct200885r] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Indexed: 12/11/2022]
Abstract
Alzheimer's disease (AD) is the most common type of senile dementia in aging populations. Amyloid β (Aβ)-mediated dysregulation of ionic homeostasis is the prevailing underlying mechanism leading to synaptic degeneration and neuronal death. Aβ-dependent ionic dysregulation most likely occurs either directly via unregulated ionic transport through the membrane or indirectly via Aβ binding to cell membrane receptors and subsequent opening of existing ion channels or transporters. Receptor binding is expected to involve a high degree of stereospecificity. Here, we investigated whether an Aβ peptide enantiomer, whose entire sequence consists of d-amino acids, can form ion-conducting channels; these channels can directly mediate Aβ effects even in the absence of receptor-peptide interactions. Using complementary approaches of planar lipid bilayer (PLB) electrophysiological recordings and molecular dynamics (MD) simulations, we show that the d-Aβ isomer exhibits ion conductance behavior in the bilayer indistinguishable from that described earlier for the l-Aβ isomer. The d isomer forms channel-like pores with heterogeneous ionic conductance similar to the l-Aβ isomer channels, and the d-isomer channel conductance is blocked by Zn(2+), a known blocker of l-Aβ isomer channels. MD simulations further verify formation of β-barrel-like Aβ channels with d- and l-isomers, illustrating that both d- and l-Aβ barrels can conduct cations. The calculated values of the single-channel conductance are approximately in the range of the experimental values. These findings are in agreement with amyloids forming Ca(2+) leaking, unregulated channels in AD, and suggest that Aβ toxicity is mediated through a receptor-independent, nonstereoselective mechanism.
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Affiliation(s)
- Ricardo Capone
- Departments of Bioengineering
and Mechanical and Aerospace Engineering and Material Science Program, University of California—San Diego, La Jolla,
California 92093, United States
| | - Hyunbum Jang
- Center for Cancer Research Nanobiology
Program, SAIC-Frederick, Incorporated,
NCI-Frederick, Frederick, Maryland 21702, United States
| | - Samuel A. Kotler
- Departments of Bioengineering
and Mechanical and Aerospace Engineering and Material Science Program, University of California—San Diego, La Jolla,
California 92093, United States
| | - Laura Connelly
- Departments of Bioengineering
and Mechanical and Aerospace Engineering and Material Science Program, University of California—San Diego, La Jolla,
California 92093, United States
| | - Fernando Teran Arce
- Departments of Bioengineering
and Mechanical and Aerospace Engineering and Material Science Program, University of California—San Diego, La Jolla,
California 92093, United States
| | - Srinivasan Ramachandran
- Departments of Bioengineering
and Mechanical and Aerospace Engineering and Material Science Program, University of California—San Diego, La Jolla,
California 92093, United States
| | - Bruce L. Kagan
- Department of Psychiatry, David
Geffen School of Medicine, Semel Institute for Neuroscience and Human
Behavior, University of California—Los Angeles, Los Angeles, California 90024, United States
| | - Ruth Nussinov
- Center for Cancer Research Nanobiology
Program, SAIC-Frederick, Incorporated,
NCI-Frederick, Frederick, Maryland 21702, United States
- Department of Human Molecular
Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ratnesh Lal
- Departments of Bioengineering
and Mechanical and Aerospace Engineering and Material Science Program, University of California—San Diego, La Jolla,
California 92093, United States
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45
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Capone R, Jang H, Kotler S, Kagan BL, Nussinov R, Lal R. Probing structural features of Alzheimer's amyloid-β pores in bilayers using site-specific amino acid substitutions. Biochemistry 2012; 51:776-85. [PMID: 22242635 PMCID: PMC3265145 DOI: 10.1021/bi2017427] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 12/29/2011] [Indexed: 11/28/2022]
Abstract
A current hypothesis for the pathology of Alzheimer's disease (AD) proposes that amyloid-β (Aβ) peptides induce uncontrolled, neurotoxic ion flux across cellular membranes. The mechanism of ion flux is not fully understood because no experiment-based Aβ channel structures at atomic resolution are currently available (only a few polymorphic states have been predicted by computational models). Structural models and experimental evidence lend support to the view that the Aβ channel is an assembly of loosely associated mobile β-sheet subunits. Here, using planar lipid bilayers and molecular dynamics (MD) simulations, we show that amino acid substitutions can be used to infer which residues are essential for channel structure. We created two Aβ(1-42) peptides with point mutations: F19P and F20C. The substitution of Phe19 with Pro inhibited channel conductance. MD simulation suggests a collapsed pore of F19P channels at the lower bilayer leaflet. The kinks at the Pro residues in the pore-lining β-strands induce blockage of the solvated pore by the N-termini of the chains. The cysteine mutant is capable of forming channels, and the conductance behavior of F20C channels is similar to that of the wild type. Overall, the mutational analysis of the channel activity performed in this work tests the proposition that the channels consist of a β-sheet rich organization, with the charged/polar central strand containing the mutation sites lining the pore, and the C-terminal strands facing the hydrophobic lipid tails. A detailed understanding of channel formation and its structure should aid studies of drug design aiming to control unregulated Aβ-dependent ion fluxes.
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Affiliation(s)
- Ricardo Capone
- Department of Bioengineering,
Department of Mechanical and Aerospace Engineering, and Material Science
Program, University of California, San Diego, La Jolla, California 92093, United States
| | - Hyunbum Jang
- Center for Cancer Research Nanobiology
Program, SAIC-Frederick, Inc., National Cancer Institute-Frederick, Frederick, Maryland 21702, United States
| | - Samuel
A. Kotler
- Department of Bioengineering,
Department of Mechanical and Aerospace Engineering, and Material Science
Program, University of California, San Diego, La Jolla, California 92093, United States
| | - Bruce L. Kagan
- Department of Psychiatry, David
Geffen School of Medicine, Semel Institute for Neuroscience and Human
Behavior, University of California, Los
Angeles, California 90024, United States
| | - Ruth Nussinov
- Center for Cancer Research Nanobiology
Program, SAIC-Frederick, Inc., National Cancer Institute-Frederick, Frederick, Maryland 21702, United States
- Department of Human Molecular
Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ratnesh Lal
- Department of Bioengineering,
Department of Mechanical and Aerospace Engineering, and Material Science
Program, University of California, San Diego, La Jolla, California 92093, United States
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46
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Kagan BL. Membrane pores in the pathogenesis of neurodegenerative disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 107:295-325. [PMID: 22482454 DOI: 10.1016/b978-0-12-385883-2.00001-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The neurodegenerative diseases described in this volume, as well as many nonneurodegenerative diseases, are characterized by deposits known as amyloid. Amyloid has long been associated with these various diseases as a pathological marker and has been implicated directly in the molecular pathogenesis of disease. However, increasing evidence suggests that these proteinaceous Congo red staining deposits may not be toxic or destructive of tissue. Recent studies strongly implicate smaller aggregates of amyloid proteins as the toxic species underlying these neurodegenerative diseases. Despite the outward obvious differences among these clinical syndromes, there are some striking similarities in their molecular pathologies. These include dysregulation of intracellular calcium levels, impairment of mitochondrial function, and the ability of virtually all amyloid peptides to form ion-permeable pores in lipid membranes. Pore formation is enhanced by environmental factors that promote protein aggregation and is inhibited by agents, such as Congo red, which prevent aggregation. Remarkably, the pores formed by a variety of amyloid peptides from neurodegenerative and other diseases share a common set of physiologic properties. These include irreversible insertion of the pores in lipid membranes, formation of heterodisperse pore sizes, inhibition by Congo red of pore formation, blockade of pores by zinc, and a relative lack of ion selectivity and voltage dependence. Although there exists some information about the physical structure of these pores, molecular modeling suggests that 4-6-mer amyloid subunits may assemble into 24-mer pore-forming aggregates. The molecular structure of these pores may resemble the β-barrel structure of the toxics pore formed by bacterial toxins, such as staphylococcal α-hemolysin, anthrax toxin, and Clostridium perfringolysin.
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Affiliation(s)
- Bruce L Kagan
- Department of Psychiatry & Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Semel Institute for Neuroscience and Human Behavior, Los Angeles, California, USA
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47
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Allen MJ, Lacroix JJ, Ramachandran S, Capone R, Whitlock JL, Ghadge GD, Arnsdorf MF, Roos RP, Lal R. Mutant SOD1 forms ion channel: implications for ALS pathophysiology. Neurobiol Dis 2011; 45:831-8. [PMID: 21930207 DOI: 10.1016/j.nbd.2011.08.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 08/18/2011] [Accepted: 08/31/2011] [Indexed: 10/17/2022] Open
Abstract
Point mutations in the gene encoding copper-zinc superoxide dismutase (SOD1) impart a gain-of-function to this protein that underlies 20-25% of all familial amyotrophic lateral sclerosis (FALS) cases. However, the specific mechanism of mutant SOD1 toxicity has remained elusive. Using the complementary techniques of atomic force microscopy (AFM), electrophysiology, and cell and molecular biology, here we examine the structure and activity of A4VSOD1, a mutant SOD1. AFM of A4VSOD1 reconstituted in lipid membrane shows discrete tetrameric pore-like structure with outer and inner diameters 12.2 and 3.0nm respectively. Electrophysiological recordings show distinct ionic conductances across bilayer for A4VSOD1 and none for wildtype SOD1. Mouse neuroblastoma cells exposed to A4VSOD1 undergo membrane depolarization and increases in intracellular calcium. These results provide compelling new evidence that a mutant SOD1 is capable of disrupting cellular homeostasis via an unregulated ion channel mechanism. Such a "toxic channel" mechanism presents a new therapeutic direction for ALS research.
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Affiliation(s)
- Michael J Allen
- Center for Nanomedicine and Section of Pulmonary/Critical Care, Department of Medicine, The University of Chicago, Chicago, IL, USA
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48
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Chiu WT, Shen SC, Yang LY, Chow JM, Wu CY, Chen YC. Inhibition of HSP90-dependent telomerase activity in amyloid β-induced apoptosis of cerebral endothelial cells. J Cell Physiol 2011; 226:2041-51. [DOI: 10.1002/jcp.22536] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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49
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Jang H, Arce F, Mustata M, Ramachandran S, Capone R, Nussinov R, Lal R. Antimicrobial protegrin-1 forms amyloid-like fibrils with rapid kinetics suggesting a functional link. Biophys J 2011; 100:1775-83. [PMID: 21463591 PMCID: PMC3072611 DOI: 10.1016/j.bpj.2011.01.072] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 01/19/2011] [Accepted: 01/21/2011] [Indexed: 11/17/2022] Open
Abstract
Protegrin-1 (PG-1) is an 18 residues long, cysteine-rich β-sheet antimicrobial peptide (AMP). PG-1 induces strong cytotoxic activities on cell membrane and acts as a potent antibiotic agent. Earlier we reported that its cytotoxicity is mediated by its channel-forming ability. In this study, we have examined the amyloidogenic fibril formation properties of PG-1 in comparison with a well-defined amyloid, the amyloid-β (Aβ(1-42)) peptide. We have used atomic force microscopy (AFM) and thioflavin-T staining to investigate the kinetics of PG-1 fibrils growth and molecular dynamics simulations to elucidate the underlying mechanism. AFM images of PG-1 on a highly hydrophilic surface (mica) show fibrils with morphological similarities to Aβ(1-42) fibrils. Real-time AFM imaging of fibril growth suggests that PG-1 fibril growth follows a relatively fast kinetics compared to the Aβ(1-42) fibrils. The AFM results are in close agreement with results from thioflavin-T staining data. Furthermore, the results indicate that PG-1 forms fibrils in solution. Significantly, in contrast, we do not detect fibrillar structures of PG-1 on an anionic lipid bilayer 2-dioleoyl-sn-glycero-3-phospho-L-serine/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine; only small PG-1 oligomers can be observed. Molecular dynamics simulations are able to identify the presence of these small oligomers on the membrane bilayer. Thus, our current results show that cytotoxic AMP PG-1 is amyloidogenic and capable of forming fibrils. Overall, comparing β-rich AMPs and amyloids such as Aβ, in addition to cytotoxicity and amyloidogenicity, they share a common structural motif, and are channel forming. These combined properties support a functional relationship between amyloidogenic peptides and β-sheet-rich cytolytic AMPs, suggesting that amyloids channels may have an antimicrobial function.
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Affiliation(s)
- Hyunbum Jang
- Center for Cancer Research Nanobiology Program, National Cancer Institute-Frederick, SAIC-Frederick, Frederick, Maryland
| | - Fernando Teran Arce
- Department of Bioengineering and Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California
| | - Mirela Mustata
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois
| | - Srinivasan Ramachandran
- Department of Bioengineering and Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California
| | - Ricardo Capone
- Department of Bioengineering and Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California
| | - Ruth Nussinov
- Center for Cancer Research Nanobiology Program, National Cancer Institute-Frederick, SAIC-Frederick, Frederick, Maryland
- Sackler Institute of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ratnesh Lal
- Department of Bioengineering and Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California
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50
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Butterfield SM, Lashuel HA. Amyloidogenic protein-membrane interactions: mechanistic insight from model systems. Angew Chem Int Ed Engl 2011; 49:5628-54. [PMID: 20623810 DOI: 10.1002/anie.200906670] [Citation(s) in RCA: 483] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The toxicity of amyloid-forming proteins is correlated with their interactions with cell membranes. Binding events between amyloidogenic proteins and membranes result in mutually disruptive structural perturbations, which are associated with toxicity. Membrane surfaces promote the conversion of amyloid-forming proteins into toxic aggregates, and amyloidogenic proteins, in turn, compromise the structural integrity of the cell membrane. Recent studies with artificial model membranes have highlighted the striking resemblance of the mechanisms of membrane permeabilization of amyloid-forming proteins to those of pore-forming toxins and antimicrobial peptides.
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Affiliation(s)
- Sara M Butterfield
- Laboratory of Molecular Neurobiology and Neuroproteomics, Swiss Federal Institute of Technology Lausanne (EPFL), SV-BMI-LMNN AI2351, 1015 Lausanne, Switzerland
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