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Rodina N, Hornung S, Sarkar R, Suladze S, Peters C, Schmid PWN, Niu Z, Haslbeck M, Buchner J, Kapurniotu A, Reif B. Modulation of Alzheimer's Disease Aβ40 Fibril Polymorphism by the Small Heat Shock Protein αB-Crystallin. J Am Chem Soc 2024; 146:19077-19087. [PMID: 38973199 PMCID: PMC11258688 DOI: 10.1021/jacs.4c03504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 07/01/2024] [Accepted: 07/02/2024] [Indexed: 07/09/2024]
Abstract
Deposition of amyloid plaques in the brains of Alzheimer's disease (AD) patients is a hallmark of the disease. AD plaques consist primarily of the beta-amyloid (Aβ) peptide but can contain other factors such as lipids, proteoglycans, and chaperones. So far, it is unclear how the cellular environment modulates fibril polymorphism and how differences in fibril structure affect cell viability. The small heat-shock protein (sHSP) alpha-B-Crystallin (αBC) is abundant in brains of AD patients, and colocalizes with Aβ amyloid plaques. Using solid-state NMR spectroscopy, we show that the Aβ40 fibril seed structure is not replicated in the presence of the sHSP. αBC prevents the generation of a compact fibril structure and leads to the formation of a new polymorph with a dynamic N-terminus. We find that the N-terminal fuzzy coat and the stability of the C-terminal residues in the Aβ40 fibril core affect the chemical and thermodynamic stability of the fibrils and influence their seeding capacity. We believe that our results yield a better understanding of how sHSP, such as αBC, that are part of the cellular environment, can affect fibril structures related to cell degeneration in amyloid diseases.
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Affiliation(s)
- Natalia Rodina
- Bayerisches
NMR Zentrum (BNMRZ) at the Department of Biosciences,
School of Natural SciencesCenter for Functional Protein Assemblies
(CPA), Department of Biosciences, Technische
Universität München, Lichtenbergstr. 4, Garching 85747, Germany
- Helmholtz-Zentrum
München (HMGU), Deutsches Forschungszentrum für Gesundheit
und Umwelt, Institute of Structural Biology (STB), Ingolstädter Landstr. 1, Neuherberg 85764, Germany
| | - Simon Hornung
- Division
of Peptide Biochemistry, TUM School of Life Sciences, Technical University of Munich, Emil-Erlenmeyer-Forum 5, Freising 85354, Germany
| | - Riddhiman Sarkar
- Bayerisches
NMR Zentrum (BNMRZ) at the Department of Biosciences,
School of Natural SciencesCenter for Functional Protein Assemblies
(CPA), Department of Biosciences, Technische
Universität München, Lichtenbergstr. 4, Garching 85747, Germany
- Helmholtz-Zentrum
München (HMGU), Deutsches Forschungszentrum für Gesundheit
und Umwelt, Institute of Structural Biology (STB), Ingolstädter Landstr. 1, Neuherberg 85764, Germany
| | - Saba Suladze
- Bayerisches
NMR Zentrum (BNMRZ) at the Department of Biosciences,
School of Natural SciencesCenter for Functional Protein Assemblies
(CPA), Department of Biosciences, Technische
Universität München, Lichtenbergstr. 4, Garching 85747, Germany
| | - Carsten Peters
- Bayerisches
NMR Zentrum (BNMRZ) at the Department of Biosciences,
School of Natural SciencesCenter for Functional Protein Assemblies
(CPA), Department of Biosciences, Technische
Universität München, Lichtenbergstr. 4, Garching 85747, Germany
| | - Philipp W. N. Schmid
- Bayerisches
NMR Zentrum (BNMRZ) at the Department of Biosciences,
School of Natural SciencesCenter for Functional Protein Assemblies
(CPA), Department of Biosciences, Technische
Universität München, Lichtenbergstr. 4, Garching 85747, Germany
| | - Zheng Niu
- School
of Pharmacy, Henan University, Kaifeng, Henan 475004, China
| | - Martin Haslbeck
- Bayerisches
NMR Zentrum (BNMRZ) at the Department of Biosciences,
School of Natural SciencesCenter for Functional Protein Assemblies
(CPA), Department of Biosciences, Technische
Universität München, Lichtenbergstr. 4, Garching 85747, Germany
| | - Johannes Buchner
- Bayerisches
NMR Zentrum (BNMRZ) at the Department of Biosciences,
School of Natural SciencesCenter for Functional Protein Assemblies
(CPA), Department of Biosciences, Technische
Universität München, Lichtenbergstr. 4, Garching 85747, Germany
| | - Aphrodite Kapurniotu
- Division
of Peptide Biochemistry, TUM School of Life Sciences, Technical University of Munich, Emil-Erlenmeyer-Forum 5, Freising 85354, Germany
| | - Bernd Reif
- Bayerisches
NMR Zentrum (BNMRZ) at the Department of Biosciences,
School of Natural SciencesCenter for Functional Protein Assemblies
(CPA), Department of Biosciences, Technische
Universität München, Lichtenbergstr. 4, Garching 85747, Germany
- Helmholtz-Zentrum
München (HMGU), Deutsches Forschungszentrum für Gesundheit
und Umwelt, Institute of Structural Biology (STB), Ingolstädter Landstr. 1, Neuherberg 85764, Germany
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Xu Y, Filice CT, Leonenko Z. Protective effect of trehalose sugar on amyloid-membrane interactions using BLM electrophysiology. Biophys J 2024; 123:1690-1704. [PMID: 38751113 PMCID: PMC11213996 DOI: 10.1016/j.bpj.2024.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 04/10/2024] [Accepted: 05/13/2024] [Indexed: 05/30/2024] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease characterized by dementia and memory loss in the elderly population. The amyloid-β peptide (Aβ) is one of the main pathogenic factors in AD and is known to cause damage to neuronal cellular membranes. There is no cure currently available for AD, and new approaches, including preventive strategies, are highly desirable. In this work, we explore the possibility of protecting neuronal membranes from amyloid-induced damage with naturally existing sugar trehalose. Trehalose has been shown to protect plant cellular membranes in extreme conditions and modify Aβ misfolding. We hypothesize that trehalose can protect the neuronal membrane from amyloid toxicity. In this work, we studied the protective effect of trehalose against Aβ1-42-induced damage in model lipid membranes (DPPC/POPC/cholesterol) using atomic force microscopy and black lipid membrane electrophysiology. Our results demonstrate that Aβ1-42 damaged membranes and led to ionic current leakage across these membranes due to the formation of various defects and pores. The presence of trehalose reduced the ion current across membranes caused by Aβ1-42 peptide damage, thus efficiently protecting the membranes. These findings suggest that the trehalose sugar can potentially be useful in protecting neuronal membranes against amyloid toxicity in AD.
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Affiliation(s)
- Yue Xu
- Department of Physics & Astronomy, University of Waterloo, Waterloo, ON, Canada
| | - Carina Teresa Filice
- Department of Biology, University of Waterloo, Waterloo, ON, Canada; Waterloo Institute for Nanotechnology, Waterloo, ON, Canada
| | - Zoya Leonenko
- Department of Physics & Astronomy, University of Waterloo, Waterloo, ON, Canada; Department of Biology, University of Waterloo, Waterloo, ON, Canada; Waterloo Institute for Nanotechnology, Waterloo, ON, Canada.
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3
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He MT, Kim JH, Cho EJ. Co-treatment with the seed of Carthamus tinctorius L. and the aerial part of Taraxacum coreanum synergistically suppresses Aβ 25-35-induced neurotoxicity by altering APP processing. Food Sci Nutr 2024; 12:1573-1580. [PMID: 38455162 PMCID: PMC10916591 DOI: 10.1002/fsn3.3768] [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: 06/28/2022] [Revised: 09/18/2023] [Accepted: 09/27/2023] [Indexed: 03/09/2024] Open
Abstract
Accumulation of β-amyloid peptide (Aβ) induces neurotoxicity, which is the primary risk factor in the pathogenesis of Alzheimer's disease (AD). The cleavage of amyloid precursor protein (APP) by the β- (BACE) and γ- (PS1, PS2) secretases is a critical step in the amyloidogenic pathway. The induction of neuronal apoptosis by Aβ involves increased expression of B-cell lymphoma protein 2 (Bcl-2)-associated X (Bax) and decreased Bcl-2 expression. The seed of Carthamus tinctorius L. (CTS) and the aerial part of Taraxacum coreanum (TC) are traditional herbs used to treat several neurodegenerative diseases. In this study, the neuroprotective effects of co-treatment with CTS and TC on Aβ-induced neurotoxicity in SH-SY5Y neuroblastoma cells and the underlying mechanisms were investigated. CTS, TC, and the co-treatment (CTS + TC) were added to Aβ25-35-treated SH-SY5Y cells. CTS + TC synergistically increased cell viability and inhibited reactive oxygen species production. CTS + TC resulted in significant downregulation of BACE, PS1, PS2, and APP, as well as the 99-aa C-terminal domain of APP, compared with either CTS or TC alone. Compared with the single herbs, co-treatment with CTS and TC markedly decreased the expression of Bax and increased the expression of Bcl-2, consistent with its anti-apoptotic effects. These findings suggest that co-treatment with CTS and TC may be useful for AD prevention.
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Affiliation(s)
- Mei Tong He
- College of Korean MedicineGachon UniversitySeongnamKorea
| | - Ji Hyun Kim
- Department of Food Science and NutritionGyeongsang National UniversityJinjuKorea
| | - Eun Ju Cho
- Department of Food Science and Nutrition & Kimchi Research InstitutePusan National UniversityBusanKorea
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4
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Howitz WJ, Guaglianone G, McKnelly KJ, Haduong K, Ashby SN, Laayouni M, Nowick JS. Macrocyclic Peptides Derived from Familial Alzheimer's Disease Mutants Show Charge-Dependent Oligomeric Assembly and Toxicity. ACS Chem Neurosci 2022; 13:714-720. [PMID: 35191689 PMCID: PMC9042422 DOI: 10.1021/acschemneuro.1c00833] [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] [Indexed: 11/30/2022] Open
Abstract
This work probes the role of charge in the oligomeric assembly, toxicity, and membrane destabilization of a series of peptides derived from Aβ and the E22Q and E22K familial mutants. In the mutant Aβ peptides, an acidic residue (E) is replaced with either a neutral or basic residue (Q or K), thus altering the net charge of the peptide. Acetylation at peripheral positions permits modulation of charge of the peptides and allows investigation of the role of charge in their oligomeric assembly, cytotoxicity, and membrane disruption. Peptides with the same net charge generally behave similarly even if the amino acid residue at position 22 differs. As the net charge of the peptide decreases, so does the extent of assembly, cytotoxicity, and membrane destabilization, which were determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, lactate dehydrogenase (LDH)-release assays with SH-SY5Y cells, and dye leakage assays using liposomes. These findings suggest that the charge of the amino acid side chain, rather than its size or hydrophobicity, accounts for the differences in the oligomeric assembly and toxicity of the E22 familial mutants of Aβ.
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Affiliation(s)
- William J Howitz
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Gretchen Guaglianone
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Kate J McKnelly
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Katelyn Haduong
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Shareen N Ashby
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Mohamed Laayouni
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - James S Nowick
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States.,Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, California 92697, United States
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5
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Zakany F, Szabo M, Batta G, Kárpáti L, Mándity IM, Fülöp P, Varga Z, Panyi G, Nagy P, Kovacs T. An ω-3, but Not an ω-6 Polyunsaturated Fatty Acid Decreases Membrane Dipole Potential and Stimulates Endo-Lysosomal Escape of Penetratin. Front Cell Dev Biol 2021; 9:647300. [PMID: 33912562 PMCID: PMC8074792 DOI: 10.3389/fcell.2021.647300] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 03/22/2021] [Indexed: 12/21/2022] Open
Abstract
Although the largely positive intramembrane dipole potential (DP) may substantially influence the function of transmembrane proteins, its investigation is deeply hampered by the lack of measurement techniques suitable for high-throughput examination of living cells. Here, we describe a novel emission ratiometric flow cytometry method based on F66, a 3-hydroxiflavon derivative, and demonstrate that 6-ketocholestanol, cholesterol and 7-dehydrocholesterol, saturated stearic acid (SA) and ω-6 γ-linolenic acid (GLA) increase, while ω-3 α-linolenic acid (ALA) decreases the DP. These changes do not correlate with alterations in cell viability or membrane fluidity. Pretreatment with ALA counteracts, while SA or GLA enhances cholesterol-induced DP elevations. Furthermore, ALA (but not SA or GLA) increases endo-lysosomal escape of penetratin, a cell-penetrating peptide. In summary, we have developed a novel method to measure DP in large quantities of individual living cells and propose ALA as a physiological DP lowering agent facilitating cytoplasmic entry of penetratin.
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Affiliation(s)
- Florina Zakany
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Mate Szabo
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gyula Batta
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Levente Kárpáti
- Department of Organic Chemistry, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary
| | - István M. Mándity
- Department of Organic Chemistry, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary
- Lendület-Artificial Chloride Ion Transporter Group, Institute of Materials and Environmental Chemistry, Research Center for Natural Sciences, Budapest, Hungary
| | - Péter Fülöp
- Division of Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Zoltan Varga
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gyorgy Panyi
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Peter Nagy
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamas Kovacs
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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6
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Patnaik D, Pao PC, Zhao WN, Silva MC, Hylton NK, Chindavong PS, Pan L, Tsai LH, Haggarty SJ. Exifone Is a Potent HDAC1 Activator with Neuroprotective Activity in Human Neuronal Models of Neurodegeneration. ACS Chem Neurosci 2021; 12:271-284. [PMID: 33417763 DOI: 10.1021/acschemneuro.0c00308] [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] [Indexed: 12/14/2022] Open
Abstract
Genomic instability caused by a deficiency in the DNA damage response and repair has been linked to age-related cognitive decline and neurodegenerative diseases. Preventing genomic instability that ultimately leads to neuronal death may provide a broadly effective strategy to protect against multiple potential genotoxic stressors. Recently, the zinc-dependent class I histone deacetylase (HDAC1) has been identified as a critical factor for protecting neurons from deleterious effects of DNA damage in Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and frontotemporal dementia (FTD). Translating these observations to a novel neuroprotective therapy for AD, ALS, and FTD may be advanced by the identification of small molecules capable of increasing the deacetylase activity of HDAC1 selectively over other structurally similar HDACs. Here, we demonstrate that exifone, a drug previously shown to be effective in treating cognitive deficits associated with AD and Parkinson's disease, the molecular mechanism of which has remained poorly understood, potently activates the deacetylase activity of HDAC1. We show that exifone acts as a mixed, nonessential activator of HDAC1 that is capable of binding to both free and substrate-bound enzyme, resulting in an increased relative maximal rate of HDAC1-catalyzed deacetylation. Exifone can directly bind to HDAC1 based upon biolayer interferometry assays with kinetic and selectivity profiling, suggesting that HDAC1 is preferentially targeted compared to other class I HDACs and the kinase CDK5, which have also been implicated in neurodegeneration. Consistent with a mechanism of deacetylase activation intracellularly, the treatment of human induced pluripotent stem cell (iPSC)-derived neuronal cells resulted in globally decreased histone acetylation. Moreover, exifone treatment was neuroprotective in a tauopathy patient iPSC-derived neuronal model subject to oxidative stress. Taken together, these findings reveal exifone as a potent activator of HDAC1-mediated deacetylation, thereby offering a lead for novel therapeutic development aiming to protect genomic integrity in the context of neurodegeneration and aging.
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Affiliation(s)
- Debasis Patnaik
- Chemical Neurobiology Laboratory, Center for Genomic Medicine, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, Massachusetts 02114, United States
- Departments of Psychiatry & Neurology, Massachusetts General Hospital & Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Ping-Chieh Pao
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Wen-Ning Zhao
- Chemical Neurobiology Laboratory, Center for Genomic Medicine, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, Massachusetts 02114, United States
- Departments of Psychiatry & Neurology, Massachusetts General Hospital & Harvard Medical School, Boston, Massachusetts 02114, United States
| | - M. Catarina Silva
- Chemical Neurobiology Laboratory, Center for Genomic Medicine, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, Massachusetts 02114, United States
- Departments of Psychiatry & Neurology, Massachusetts General Hospital & Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Norma K. Hylton
- Chemical Neurobiology Laboratory, Center for Genomic Medicine, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, Massachusetts 02114, United States
- Departments of Psychiatry & Neurology, Massachusetts General Hospital & Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Peter S. Chindavong
- Chemical Neurobiology Laboratory, Center for Genomic Medicine, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, Massachusetts 02114, United States
- Departments of Psychiatry & Neurology, Massachusetts General Hospital & Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Ling Pan
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Li-Huei Tsai
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Stephen J. Haggarty
- Chemical Neurobiology Laboratory, Center for Genomic Medicine, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, Massachusetts 02114, United States
- Departments of Psychiatry & Neurology, Massachusetts General Hospital & Harvard Medical School, Boston, Massachusetts 02114, United States
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7
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Normalizing polydiacetylene colorimetric assays of vesicle binding across lipid systems. Anal Biochem 2020; 609:113864. [DOI: 10.1016/j.ab.2020.113864] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 06/24/2020] [Accepted: 07/07/2020] [Indexed: 11/18/2022]
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8
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Direct and indirect cholesterol effects on membrane proteins with special focus on potassium channels. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158706. [DOI: 10.1016/j.bbalip.2020.158706] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 03/19/2020] [Accepted: 03/30/2020] [Indexed: 12/16/2022]
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9
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Alvarez AB, Caruso B, Rodríguez PEA, Petersen SB, Fidelio GD. Aβ-Amyloid Fibrils Are Self-Triggered by the Interfacial Lipid Environment and Low Peptide Content. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:8056-8065. [PMID: 32551671 DOI: 10.1021/acs.langmuir.0c00468] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We studied the surface properties of Aβ(1-40) amyloid peptides mixed with 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) (liquid state) or 1,2-disteraoyl-phosphatidylcholine (DSPC) (solid state) phospholipids by using nanostructured lipid/peptide films (Langmuir monolayers). Pure Aβ(1-40) amyloid peptides form insoluble monolayers without forming fibril-like structures. In a lipid environment [phospholipid/Aβ(1-40) peptide mixtures], we observed that both miscibility and stability of the films depend on the peptide content. At low Aβ(1-40) amyloid peptide proportion (from 2.5 to 10% of peptide area proportion), we observed the formation of a fibril-like structure when mixed only with POPC lipids. The stability acquired by these mixed films is within 20-35 mN·m-1 compatible with the equivalent surface pressure postulated for natural biomembranes. Fibrils are clearly evidenced directly from the monolayers by using Brewster angle microscopy. The so-called nanostructured fibrils are thioflavin T positive when observed by fluorescence microscopy. The amyloid fibril network at the surface was also evidenced by atomic force microscopy when the films are transferred onto a mica support. Aβ(1-40) amyloid mixed with the solid DSPC lipid showed an immiscible behavior in all peptide proportions without fibril formation. We postulated that the amyloid fibrillogenesis at the membrane can be dynamically nano-self-triggered at the surface by the quality of the interfacial environment, that is, the physical state of the water-lipid interface and the relative content of amyloid protein present at the interface.
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Affiliation(s)
- Alain Bolaño Alvarez
- Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Cordoba X5000HUA, Argentina
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, CONICET, Universidad Nacional de Córdoba, Cordoba X5000HUA, Argentina
| | - Benjamín Caruso
- Cátedra de Química Biológica, Departamento de Química, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba X5016GCA, Argentina
- Instituto de Investigaciones Biológicas y Tecnológicas (IIBYT), CONICET, Universidad Nacional de Córdoba, Córdoba X5016GCA, Argentina
| | - Pablo E A Rodríguez
- Ministerio de Ciencia y Tecnología de la Provincia de Córdoba, Cordoba X5004AAP, Argentina
| | - Steffen B Petersen
- Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg 9220, Denmark
| | - Gerardo D Fidelio
- Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Cordoba X5000HUA, Argentina
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, CONICET, Universidad Nacional de Córdoba, Cordoba X5000HUA, Argentina
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10
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Jakob DS, Wang H, Zeng G, Otzen DE, Yan Y, Xu XG. Peak Force Infrared-Kelvin Probe Force Microscopy. Angew Chem Int Ed Engl 2020; 59:16083-16090. [PMID: 32463936 DOI: 10.1002/anie.202004211] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/10/2020] [Indexed: 12/20/2022]
Abstract
Correlative scanning probe microscopy of chemical identity, surface potential, and mechanical properties provide insight into the structure-function relationships of nanomaterials. However, simultaneous measurement with comparable and high resolution is a challenge. We seamlessly integrated nanoscale photothermal infrared imaging with Coulomb force detection to form peak force infrared-Kelvin probe force microscopy (PFIR-KPFM), which enables simultaneous nanomapping of infrared absorption, surface potential, and mechanical properties with approximately 10 nm spatial resolution in a single-pass scan. MAPbBr3 perovskite crystals of different degradation pathways were studied in situ. Nanoscale charge accumulations were observed in MAPbBr3 near the boundary to PbBr2 . PFIR-KPFM also revealed correlations between residual charges and secondary conformation in amyloid fibrils. PFIR-KPFM is applicable to other heterogeneous materials at the nanoscale for correlative multimodal characterizations.
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Affiliation(s)
- Devon S Jakob
- Department of Chemistry, Lehigh University, 6 E Packer Ave., Bethlehem, PA, 18015, USA
| | - Haomin Wang
- Department of Chemistry, Lehigh University, 6 E Packer Ave., Bethlehem, PA, 18015, USA
| | - Guanghong Zeng
- DFM A/S, Danish National Metrology Institute, Kogle Alle 5, 2970, Hørsholm, Denmark
| | - Daniel E Otzen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wields Vej 14, 8000, Aarhus C, Denmark
| | - Yong Yan
- Department of Chemistry, San Diego State University, 5500 Campanile Dr., San Diego, CA, 92182, USA
| | - Xiaoji G Xu
- Department of Chemistry, Lehigh University, 6 E Packer Ave., Bethlehem, PA, 18015, USA
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11
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Jakob DS, Wang H, Zeng G, Otzen DE, Yan Y, Xu XG. Peak Force Infrared–Kelvin Probe Force Microscopy. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202004211] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Devon S. Jakob
- Department of Chemistry Lehigh University 6 E Packer Ave. Bethlehem PA 18015 USA
| | - Haomin Wang
- Department of Chemistry Lehigh University 6 E Packer Ave. Bethlehem PA 18015 USA
| | - Guanghong Zeng
- DFM A/S, Danish National Metrology Institute Kogle Alle 5 2970 Hørsholm Denmark
| | - Daniel E. Otzen
- Interdisciplinary Nanoscience Center (iNANO) Aarhus University Gustav Wields Vej 14 8000 Aarhus C Denmark
| | - Yong Yan
- Department of Chemistry San Diego State University 5500 Campanile Dr. San Diego CA 92182 USA
| | - Xiaoji G. Xu
- Department of Chemistry Lehigh University 6 E Packer Ave. Bethlehem PA 18015 USA
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12
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Martial B, Raîche-Marcoux G, Lefèvre T, Audet P, Voyer N, Auger M. Structure of a Parkinson’s Disease-Involved α-Synuclein Peptide Is Modulated by Membrane Composition and Physical State. J Phys Chem B 2020; 124:3469-3481. [DOI: 10.1021/acs.jpcb.0c00945] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Benjamin Martial
- Department of Chemistry, Regroupement québécois de recherche sur la fonction, l’ingénierie et les applications des protéines (PROTEO), Centre de recherche sur les matériaux avancés (CERMA), Centre québécois sur les matériaux fonctionnels (CQMF), Université Laval, 1045 avenue de la médecine, Québec, Quebec G1V 0A6, Canada
| | - Gabrielle Raîche-Marcoux
- Department of Chemistry, Regroupement québécois de recherche sur la fonction, l’ingénierie et les applications des protéines (PROTEO), Centre de recherche sur les matériaux avancés (CERMA), Centre québécois sur les matériaux fonctionnels (CQMF), Université Laval, 1045 avenue de la médecine, Québec, Quebec G1V 0A6, Canada
| | - Thierry Lefèvre
- Department of Chemistry, Regroupement québécois de recherche sur la fonction, l’ingénierie et les applications des protéines (PROTEO), Centre de recherche sur les matériaux avancés (CERMA), Centre québécois sur les matériaux fonctionnels (CQMF), Université Laval, 1045 avenue de la médecine, Québec, Quebec G1V 0A6, Canada
| | - Pierre Audet
- Department of Chemistry, Université Laval, 1045 avenue de la médecine, Québec, Quebec G1V 0A6, Canada
| | - Normand Voyer
- Department of Chemistry, Regroupement québécois de recherche sur la fonction, l’ingénierie et les applications des protéines (PROTEO), Université Laval, 1045 avenue de la médecine, Québec, Quebec G1V 0A6, Canada
| | - Michèle Auger
- Department of Chemistry, Regroupement québécois de recherche sur la fonction, l’ingénierie et les applications des protéines (PROTEO), Centre de recherche sur les matériaux avancés (CERMA), Centre québécois sur les matériaux fonctionnels (CQMF), Université Laval, 1045 avenue de la médecine, Québec, Quebec G1V 0A6, Canada
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13
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Dias CL, Jalali S, Yang Y, Cruz L. Role of Cholesterol on Binding of Amyloid Fibrils to Lipid Bilayers. J Phys Chem B 2020; 124:3036-3042. [DOI: 10.1021/acs.jpcb.0c00485] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Cristiano L. Dias
- Department of Physics, New Jersey Institute of Technology, Newark, New Jersey 07102-1982, United States
| | - Sharareh Jalali
- Department of Physics, New Jersey Institute of Technology, Newark, New Jersey 07102-1982, United States
| | - Yanxing Yang
- Department of Physics, New Jersey Institute of Technology, Newark, New Jersey 07102-1982, United States
| | - Luis Cruz
- Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States
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14
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Deng M, Huang L, Zhong X. β‑asarone modulates Beclin‑1, LC3 and p62 expression to attenuate Aβ40 and Aβ42 levels in APP/PS1 transgenic mice with Alzheimer's disease. Mol Med Rep 2020; 21:2095-2102. [PMID: 32186763 PMCID: PMC7115210 DOI: 10.3892/mmr.2020.11026] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 01/22/2020] [Indexed: 12/14/2022] Open
Abstract
Alzheimer's disease (AD) is a common neurodegenerative disease in the elderly population. Autophagy is a well-known regulator of neurodegenerative diseases and β-asarone has been discovered to have certain neuropharmacological effects. Thus, the present study aimed to analyze the potential effects of β-asarone in AD and its possible mechanism of action in relation to autophagy. The present study investigated the effects of β-asarone on the number of senile plaques and amyloid β(Aβ)40, Aβ42, amyloid precursor protein (APP) and Beclin-1 mRNA levels in the hippocampus of APP/presenilin-1 (PS1) transgenic mice. The possible mechanism of β-asarone on autophagy-related proteins, including Beclin-1, light chain (LC)3A, LC3B and p62 levels, and the number of autophagosomes was also investigated. Mice were divided into a normal control group, a model group, a β-asarone-treated group, a 3-MA-treated group and a rapamycin-treated group. Treatments were continuously administered to all mice for 30 days by intragastric administration. The mice, including those in the normal and model control groups, were given equal volumes of saline. It was demonstrated that β-asarone treatment reduced the number of senile plaques and autophagosomes, and decreased Aβ40, Aβ42, APP and Beclin-1 expression in the hippocampus of model mice compared with untreated model mice. β-asarone also inhibited LC3A/B expression levels, but increased p62 expression. It was deduced that the neuroprotective effects of β-asarone in APP/PS1 transgenic mice resulted from its inhibition of autophagy. In conclusion, the data suggested that β-asarone should be explored further as a potential therapeutic agent in AD.
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Affiliation(s)
- Minzhen Deng
- Department of Neurology, Guangdong Provincial Hospital of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510120, P.R. China
| | - Liping Huang
- Department of Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, Lingnan Normal University, Zhanjiang, Guangdong 524048, P.R. China
| | - Xiaoqin Zhong
- Department of Neurology, Guangdong Provincial Hospital of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510120, P.R. China
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15
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Fabiani C, Antollini SS. Alzheimer's Disease as a Membrane Disorder: Spatial Cross-Talk Among Beta-Amyloid Peptides, Nicotinic Acetylcholine Receptors and Lipid Rafts. Front Cell Neurosci 2019; 13:309. [PMID: 31379503 PMCID: PMC6657435 DOI: 10.3389/fncel.2019.00309] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 06/25/2019] [Indexed: 12/17/2022] Open
Abstract
Biological membranes show lateral and transverse asymmetric lipid distribution. Cholesterol (Chol) localizes in both hemilayers, but in the external one it is mostly condensed in lipid-ordered microdomains (raft domains), together with saturated phosphatidyl lipids and sphingolipids (including sphingomyelin and glycosphingolipids). Membrane asymmetries induce special membrane biophysical properties and behave as signals for several physiological and/or pathological processes. Alzheimer’s disease (AD) is associated with a perturbation in different membrane properties. Amyloid-β (Aβ) plaques and neurofibrillary tangles of tau protein together with neuroinflammation and neurodegeneration are the most characteristic cellular changes observed in this disease. The extracellular presence of Aβ peptides forming senile plaques, together with soluble oligomeric species of Aβ, are considered the major cause of the synaptic dysfunction of AD. The association between Aβ peptide and membrane lipids has been extensively studied. It has been postulated that Chol content and Chol distribution condition Aβ production and posterior accumulation in membranes and, hence, cell dysfunction. Several lines of evidence suggest that Aβ partitions in the cell membrane accumulate mostly in raft domains, the site where the cleavage of the precursor AβPP by β- and γ- secretase is also thought to occur. The main consequence of the pathogenesis of AD is the disruption of the cholinergic pathways in the cerebral cortex and in the basal forebrain. In parallel, the nicotinic acetylcholine receptor has been extensively linked to membrane properties. Since its transmembrane domain exhibits extensive contacts with the surrounding lipids, the acetylcholine receptor function is conditioned by its lipid microenvironment. The nicotinic acetylcholine receptor is present in high-density clusters in the cell membrane where it localizes mainly in lipid-ordered domains. Perturbations of sphingomyelin or cholesterol composition alter acetylcholine receptor location. Therefore, Aβ processing, Aβ partitioning, and acetylcholine receptor location and function can be manipulated by changes in membrane lipid biophysics. Understanding these mechanisms should provide insights into new therapeutic strategies for prevention and/or treatment of AD. Here, we discuss the implications of lipid-protein interactions at the cell membrane level in AD.
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Affiliation(s)
- Camila Fabiani
- Instituto de Investigaciones Bioquímicas de Bahía Blanca CONICET-UNS, Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Silvia S Antollini
- Instituto de Investigaciones Bioquímicas de Bahía Blanca CONICET-UNS, Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina
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16
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Structure of amyloid β 25-35 in lipid environment and cholesterol-dependent membrane pore formation. Sci Rep 2019; 9:2689. [PMID: 30804528 PMCID: PMC6389947 DOI: 10.1038/s41598-019-38749-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 01/08/2019] [Indexed: 01/14/2023] Open
Abstract
The amyloid β (Aβ) peptide and its shorter variants, including a highly cytotoxic Aβ25–35 peptide, exert their neurotoxic effect during Alzheimer’s disease by various mechanisms, including cellular membrane permeabilization. The intrinsic polymorphism of Aβ has prevented the identification of the molecular basis of Aβ pore formation by direct structural methods, and computational studies have led to highly divergent pore models. Here, we have employed a set of biophysical techniques to directly monitor Ca2+-transporting Aβ25–35 pores in lipid membranes, to quantitatively characterize pore formation, and to identify the key structural features of the pore. Moreover, the effect of membrane cholesterol on pore formation and the structure of Aβ25–35 has been elucidated. The data suggest that the membrane-embedded peptide forms 6- or 8-stranded β-barrel like structures. The 8-stranded barrels may conduct Ca2+ ions through an inner cavity, whereas the tightly packed 6-stranded barrels need to assemble into supramolecular structures to form a central pore. Cholesterol affects Aβ25–35 pore formation by a dual mechanism, i.e., by direct interaction with the peptide and by affecting membrane structure. Collectively, our data illuminate the molecular basis of Aβ membrane pore formation, which should advance both basic and clinical research on Alzheimer’s disease and membrane-associated pathologies in general.
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17
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Singh J, Peric M. Interaction of the β amyloid - Aβ(25-35) - peptide with zwitterionic and negatively charged vesicles with and without cholesterol. Chem Phys Lipids 2018; 216:39-47. [PMID: 30222975 DOI: 10.1016/j.chemphyslip.2018.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 09/07/2018] [Accepted: 09/11/2018] [Indexed: 12/11/2022]
Abstract
The interactions of the Alzheimer's β-amyloid peptide, Aβ(25-35), with 18:1 (Δ9-Cis) PC 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), L-α-phosphatidylcholine (EPC), 1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (sodium salt) (DOPG), and L-α-phosphatidylglycerol (EPG) phospholipid vesicles with and without cholesterol (Ch) are studied by the nitroxide spin probe electron paramagnetic resonance (EPR) method. Two nitroxide spin probes, 2,2,6,6-tetramethyl-piperidin-1-oxyl-4-yl hexadecanoate (TP, TEMPO-Palmitate) and 2-Ethyl-2-(15-methoxy-15-oxopentadecyl)-4,4-dimethyl-3-oxazolidinyloxy (16-DSE), are utilized in the study. TEMPO-Palmitate has the reporting EPR moiety located at the top of this spin probe, while 16-DSE has the reporting EPR moiety located at the tail of the spin probe. These two probes enable us to sample the surface and the middle of the phospholipid bilayer, respectively. All EPR measurements are done above the melting points of all four phospholipids when the bilayer is in the liquid crystal phase, the physiologically relevant phase. Due to non-linear spectral line fitting, the EPR spectral parameters are extracted with high precision. The results show that there are two populations of Aβ(25-35) and that one of them is located in the hydrophobic phospholipid layer below the hydrophilic headgroup region. The second population appears to be weakly coupled to the surface of the bilayer. Both hydrophobic and electrostatic interactions affect the insertion of Aβ(25-35) in the bilayer. Also, there is strong evidence for an interaction between cholesterol and Aβ(25-35), which affects the dielectric and dynamic properties of the bilayer.
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Affiliation(s)
- Jasmeet Singh
- Department of Physics and Astronomy and The Center for Supramolecular Studies, California State University at Northridge, Northridge, California 91330, United States
| | - Miroslav Peric
- Department of Physics and Astronomy and The Center for Supramolecular Studies, California State University at Northridge, Northridge, California 91330, United States.
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18
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Toglia P, Demuro A, Mak DOD, Ullah G. Data-driven modeling of mitochondrial dysfunction in Alzheimer's disease. Cell Calcium 2018; 76:23-35. [PMID: 30248575 DOI: 10.1016/j.ceca.2018.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 09/02/2018] [Accepted: 09/03/2018] [Indexed: 02/06/2023]
Abstract
Intracellular accumulation of oligomeric forms of β amyloid (Aβ) are now believed to play a key role in the earliest phase of Alzheimer's disease (AD) as their rise correlates well with the early symptoms of the disease. Extensive evidence points to impaired neuronal Ca2+ homeostasis as a direct consequence of the intracellular Aβ oligomers. However, little is known about the downstream effects of the resulting Ca2+ rise on the many intracellular Ca2+-dependent pathways. Here we use multiscale modeling in conjunction with patch-clamp electrophysiology of single inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) and fluorescence imaging of whole-cell Ca2+ response, induced by exogenously applied intracellular Aβ42 oligomers to show that Aβ42 inflicts cytotoxicity by impairing mitochondrial function. Driven by patch-clamp experiments, we first model the kinetics of IP3R, which is then extended to build a model for the whole-cell Ca2+ signals. The whole-cell model is then fitted to fluorescence signals to quantify the overall Ca2+ release from the endoplasmic reticulum by intracellular Aβ42 oligomers through G-protein-mediated stimulation of IP3 production. The estimated IP3 concentration as a function of intracellular Aβ42 content together with the whole-cell model allows us to show that Aβ42 oligomers impair mitochondrial function through pathological Ca2+ uptake and the resulting reduced mitochondrial inner membrane potential, leading to an overall lower ATP and increased production of reactive oxygen species and H2O2. We further show that mitochondrial function can be restored by the addition of Ca2+ buffer EGTA, in accordance with the observed abrogation of Aβ42 cytotoxicity by EGTA in our live cells experiments.
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Affiliation(s)
- Patrick Toglia
- Department of Physics, University of South Florida, Tampa, FL 33620, USA
| | - Angelo Demuro
- Department of Neurobiology and Behavior and Physiology and Biophysics, University of California, Irvine, CA 92697, USA
| | - Don-On Daniel Mak
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, FL 33620, USA.
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19
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Savelieff MG, Nam G, Kang J, Lee HJ, Lee M, Lim MH. Development of Multifunctional Molecules as Potential Therapeutic Candidates for Alzheimer’s Disease, Parkinson’s Disease, and Amyotrophic Lateral Sclerosis in the Last Decade. Chem Rev 2018; 119:1221-1322. [DOI: 10.1021/acs.chemrev.8b00138] [Citation(s) in RCA: 270] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Masha G. Savelieff
- SciGency Science Communications, Ann Arbor, Michigan 48104, United States
| | - Geewoo Nam
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Juhye Kang
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Hyuck Jin Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Misun Lee
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Mi Hee Lim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
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20
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Lee TH, Hirst DJ, Kulkarni K, Del Borgo MP, Aguilar MI. Exploring Molecular-Biomembrane Interactions with Surface Plasmon Resonance and Dual Polarization Interferometry Technology: Expanding the Spotlight onto Biomembrane Structure. Chem Rev 2018; 118:5392-5487. [PMID: 29793341 DOI: 10.1021/acs.chemrev.7b00729] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The molecular analysis of biomolecular-membrane interactions is central to understanding most cellular systems but has emerged as a complex technical challenge given the complexities of membrane structure and composition across all living cells. We present a review of the application of surface plasmon resonance and dual polarization interferometry-based biosensors to the study of biomembrane-based systems using both planar mono- or bilayers or liposomes. We first describe the optical principals and instrumentation of surface plasmon resonance, including both linear and extraordinary transmission modes and dual polarization interferometry. We then describe the wide range of model membrane systems that have been developed for deposition on the chips surfaces that include planar, polymer cushioned, tethered bilayers, and liposomes. This is followed by a description of the different chemical immobilization or physisorption techniques. The application of this broad range of engineered membrane surfaces to biomolecular-membrane interactions is then overviewed and how the information obtained using these techniques enhance our molecular understanding of membrane-mediated peptide and protein function. We first discuss experiments where SPR alone has been used to characterize membrane binding and describe how these studies yielded novel insight into the molecular events associated with membrane interactions and how they provided a significant impetus to more recent studies that focus on coincident membrane structure changes during binding of peptides and proteins. We then discuss the emerging limitations of not monitoring the effects on membrane structure and how SPR data can be combined with DPI to provide significant new information on how a membrane responds to the binding of peptides and proteins.
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Affiliation(s)
- Tzong-Hsien Lee
- Department of Biochemistry and Molecular Biology and Biomedicine Discovery Institute , Monash University , Clayton , VIC 3800 , Australia
| | - Daniel J Hirst
- Department of Biochemistry and Molecular Biology and Biomedicine Discovery Institute , Monash University , Clayton , VIC 3800 , Australia
| | - Ketav Kulkarni
- Department of Biochemistry and Molecular Biology and Biomedicine Discovery Institute , Monash University , Clayton , VIC 3800 , Australia
| | - Mark P Del Borgo
- Department of Biochemistry and Molecular Biology and Biomedicine Discovery Institute , Monash University , Clayton , VIC 3800 , Australia
| | - Marie-Isabel Aguilar
- Department of Biochemistry and Molecular Biology and Biomedicine Discovery Institute , Monash University , Clayton , VIC 3800 , Australia
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21
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Role of the cell membrane interface in modulating production and uptake of Alzheimer's beta amyloid protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1639-1651. [PMID: 29572033 DOI: 10.1016/j.bbamem.2018.03.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/13/2018] [Accepted: 03/14/2018] [Indexed: 12/22/2022]
Abstract
The beta amyloid protein (Aβ) plays a central role in Alzheimer's disease (AD) pathogenesis and its interaction with cell membranes in known to promote mutually disruptive structural perturbations that contribute to amyloid deposition and neurodegeneration in the brain. In addition to protein aggregation at the membrane interface and disruption of membrane integrity, growing reports demonstrate an important role for the membrane in modulating Aβ production and uptake into cells. The aim of this review is to highlight and summarize recent literature that have contributed insight into the implications of altered membrane composition on amyloid precursor protein (APP) proteolysis, production of Aβ, its internalization in to cells via permeabilization and receptor mediated uptake. Here, we also review the various membrane model systems and experimental tools used for probing Aβ-membrane interactions to investigate the key mechanistic aspects underlying the accumulation and toxicity of Aβ in AD.
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22
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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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23
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Zhang H, Chang Z, Mehmood K, Abbas RZ, Nabi F, Rehman MU, Wu X, Tian X, Yuan X, Li Z, Zhou D. Nano Copper Induces Apoptosis in PK-15 Cells via a Mitochondria-Mediated Pathway. Biol Trace Elem Res 2018; 181:62-70. [PMID: 28497347 DOI: 10.1007/s12011-017-1024-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 04/12/2017] [Indexed: 12/31/2022]
Abstract
Nano-sized copper particles are widely used in various chemical, physical, and biological fields. However, earlier studies have shown that nano copper particles (40-100 μg/mL) can induce cell toxicity and apoptosis. Therefore, this study was conducted to investigate the role of nano copper in mitochondrion-mediated apoptosis in PK-15 cells. The cells were treated with different doses of nano copper (20, 40, 60, and 80 μg/mL) to determine the effects of apoptosis using acridine orange/ethidium bromide (AO/EB) fluorescence staining and a flow cytometry assay. The levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in the PK-15 cells were examined using commercially available kits. Moreover, the mRNA levels of the Bax, Bid, Caspase-3, and CYCS genes were assessed by real-time PCR. The results revealed that nano copper exposure induced apoptosis and changed the mitochondrial membrane potential. In addition, nano copper significantly altered the levels of the Bax, Bid, Caspase-3, and CYCS genes at a concentration of 40 μg/mL. To summarize, nano copper significantly (P < 0.05) decreased the level of SOD and increased the level of MDA in PK-15 cells. Altogether, these results suggest that nano copper can play an important role in inducing the apoptotic pathway in PK-15 cells, which may be the mechanism by which nano copper induces nephrotoxicity.
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Affiliation(s)
- Hui Zhang
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Zhenyu Chang
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Khalid Mehmood
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- University College of Veterinary and Animal Sciences, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
| | - Rao Zahid Abbas
- Department of Parasitology, Faculty of Veterinary Science, University of Agriculture, Faisalabad, 38000, Pakistan
| | - Fazul Nabi
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Mujeeb Ur Rehman
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Xiaoxing Wu
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Xinxin Tian
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Xiaodan Yuan
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Zhaoyang Li
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Donghai Zhou
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
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24
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Kandel N, Zheng T, Huo Q, Tatulian SA. Membrane Binding and Pore Formation by a Cytotoxic Fragment of Amyloid β Peptide. J Phys Chem B 2017; 121:10293-10305. [PMID: 29039658 DOI: 10.1021/acs.jpcb.7b07002] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Amyloid β (Aβ) peptide contributes to Alzheimer's disease by a yet unidentified mechanism. In the brain tissue, Aβ occurs in various forms, including an undecapeptide Aβ25-35, which exerts a neurotoxic effect through the mitochondrial dysfunction and/or Ca2+-permeable pore formation in cell membranes. This work was aimed at the biophysical characterization of membrane binding and pore formation by Aβ25-35. Interaction of Aβ25-35 with anionic and zwitterionic membranes was analyzed by microelectrophoresis. In pore formation experiments, Aβ25-35 was incubated in aqueous buffer to form oligomers and added to Quin-2-loaded vesicles. Gradual increase in Quin-2 fluorescence was interpreted in terms of membrane pore formation by the peptide, Ca2+ influx, and binding to intravesicular Quin-2. The kinetics and magnitude of this process were used to evaluate the rate constant of pore formation, peptide-peptide association constants, and the oligomeric state of the pores. Decrease in membrane anionic charge and high ionic strength conditions significantly suppressed membrane binding and pore formation, indicating the importance of electrostatic interactions in these events. Circular dichroism spectroscopy showed that Aβ25-35 forms the most efficient pores in β-sheet conformation. The data are consistent with an oligo-oligomeric pore model composed of up to eight peptide units, each containing 6-8 monomers.
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Affiliation(s)
| | | | | | - Suren A Tatulian
- Department of Physics, University of Central Florida , Physical Sciences Bldg., Room 456, 4111 Libra Drive, Orlando, Florida 32816, United States
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25
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Kedia N, Almisry M, Bieschke J. Glucose directs amyloid-beta into membrane-active oligomers. Phys Chem Chem Phys 2017; 19:18036-18046. [PMID: 28671211 PMCID: PMC5654640 DOI: 10.1039/c7cp02849k] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Oligomeric amyloid-β 1-42 (Aβ-42) peptides are considered to be the most toxic species connected to the occurrence of Alzheimer's disease. However, not all aggregation conditions promote oligomer formation in vitro, raising the question whether oligomer formation in vivo also requires a specific suitable cellular environment. We recently found that interaction with neuronal membranes initiates aggregation of Aβ-42 and neuronal uptake. Our data suggest that small molecules in the extracellular space can facilitate the formation of membrane-active Aβ-42 oligomers. We analyzed the early stage of Aβ-42 aggregation in the presence of glucose and sucrose and found that these sugars strongly favor Aβ-42 oligomer formation. We characterized oligomers by dynamic light scattering, atomic force microscopy, immuno-transmission electron microscopy and fluorescence cross correlation spectroscopy. We found that Aβ-42 spontaneously and rapidly forms low molecular weight oligomers in the presence of sugars. Slightly acidic pH (6.7-7) greatly favors oligomer formation when compared to the extracellular physiological pH (7.4). Circular dichroism demonstrated that these Aβ-42 oligomers did not adopt a β-sheet structure. Unstructured oligomeric Aβ-42 interacted with membrane bilayers of giant unilamellar vesicles (GUV) and neuronal model cells, facilitated cellular uptake of Aβ-42, and inhibition of mitochondrial activity. Our data therefore suggest that elevated concentrations of glucose within the range observed in diabetic individuals (10 mM) facilitate the formation of membrane-active Aβ-42 oligomers.
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Affiliation(s)
- Niraja Kedia
- Department of Biomedical Engineering, Washington University, 63130 St. Louis, MO, USA.
| | - Michael Almisry
- Department of Biomedical Engineering, Washington University, 63130 St. Louis, MO, USA.
| | - Jan Bieschke
- Department of Biomedical Engineering, Washington University, 63130 St. Louis, MO, USA.
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Amino acid substitutions [K16A] and [K28A] distinctly affect amyloid β-protein oligomerization. J Biol Phys 2016; 42:453-76. [PMID: 27155979 DOI: 10.1007/s10867-016-9417-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 03/28/2016] [Indexed: 10/21/2022] Open
Abstract
Amyloid β-protein (A β) assembles into oligomers that play a seminal role in Alzheimer's disease (AD), a leading cause of dementia among the elderly. Despite undisputed importance of A β oligomers, their structure and the basis of their toxicity remain elusive. Previous experimental studies revealed that the [K16A] substitution strongly inhibits toxicity of the two predominant A β alloforms in the brain, A β 40 and A β 42, whereas the [K28A] substitution exerts only a moderate effect. Here, folding and oligomerization of [A16]A β 40, [A28]A β 40, [A16]A β 42, and [A28]A β 42 are examined by discrete molecular dynamics (DMD) combined with a four-bead implicit solvent force field, DMD4B-HYDRA, and compared to A β 40 and A β 42 oligomer formation. Our results show that both substitutions promote A β 40 and A β 42 oligomerization and that structural changes to oligomers are substitution- and alloform-specific. The [K28A] substitution increases solvent-accessible surface area of hydrophobic residues and the intrapeptide N-to-C terminal distance within oligomers more than the [K16A] substitution. The [K16A] substitution decreases the overall β-strand content, whereas the [K28A] substitution exerts only a modest change. Substitution-specific tertiary and quaternary structure changes indicate that the [K16A] substitution induces formation of more compact oligomers than the [K28A] substitution. If the structure-function paradigm applies to A β oligomers, then the observed substitution-specific structural changes in A β 40 and A β 42 oligomers are critical for understanding the structural basis of A β oligomer toxicity and correct identification of therapeutic targets against AD.
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Cording A, Gormally M, Bond PJ, Carrington M, Balasubramanian S, Miska EA, Thomas B. Selective inhibitors of trypanosomal uridylyl transferase RET1 establish druggability of RNA post-transcriptional modifications. RNA Biol 2016; 14:611-619. [PMID: 26786754 PMCID: PMC5449093 DOI: 10.1080/15476286.2015.1137422] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Non-coding RNAs are crucial regulators for a vast array of cellular processes and have been implicated in human disease. These biological processes represent a hitherto untapped resource in our fight against disease. In this work we identify small molecule inhibitors of a non-coding RNA uridylylation pathway. The TUTase family of enzymes is important for modulating non-coding RNA pathways in both human cancer and pathogen systems. We demonstrate that this new class of drug target can be accessed with traditional drug discovery techniques. Using the Trypanosoma brucei TUTase, RET1, we identify TUTase inhibitors and lay the groundwork for the use of this new target class as a therapeutic opportunity for the under-served disease area of African Trypanosomiasis. In a broader sense this work demonstrates the therapeutic potential for targeting RNA post-transcriptional modifications with small molecules in human disease.
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Affiliation(s)
- Amy Cording
- a The Gurdon Institute, University of Cambridge , Cambridge , UK
| | - Michael Gormally
- b Department of Chemistry , University of Cambridge , Cambridge , UK.,c Cancer Research UK Cambridge Institute, Li Ka Shing Center , Cambridge , UK.,d National Center for Advancing Translational Sciences , National Institutes of Health , Bethesda , MD , USA
| | - Peter J Bond
- e Bioinformatics Institute (A*STAR) , Singapore.,f Department of Biological Sciences , National University of Singapore , Singapore
| | | | - Shankar Balasubramanian
- b Department of Chemistry , University of Cambridge , Cambridge , UK.,c Cancer Research UK Cambridge Institute, Li Ka Shing Center , Cambridge , UK
| | - Eric A Miska
- a The Gurdon Institute, University of Cambridge , Cambridge , UK
| | - Beth Thomas
- b Department of Chemistry , University of Cambridge , Cambridge , UK
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de Oliveira MR. Phloretin-induced cytoprotective effects on mammalian cells: A mechanistic view and future directions. Biofactors 2016; 42:13-40. [PMID: 26826024 DOI: 10.1002/biof.1256] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 11/19/2015] [Indexed: 11/11/2022]
Abstract
Phloretin (C15 H14 O5 ), a dihydrochalcone flavonoid, is mainly found in fruit, leaves, and roots of apple tree. Phloretin exerts antioxidant, anti-inflammatory, and anti-tumor activities in mammalian cells through mechanisms that have been partially elucidated throughout the years. Phloretin bioavailability is well known in humans, but still remains to be better studied in experimental animals, such as mouse and rat. The focus of the present review is to gather information regarding the mechanisms involved in the phloretin-elicited effects in different in vitro and in vivo experimental models. Several manuscripts were analyzed and data raised by authors were described and discussed here in a mechanistic manner. Comparisons between the effects elicited by phloretin and phloridzin were made whenever possible, as well as with other polyphenols, clarifying questions about the use of phloretin as a potential therapeutic agent. Toxicological aspects associated to phloretin exposure were also discussed here. Furthermore, a special section containing future directions was created as a suggestive guide towards the elucidation of phloretin-related actions in mammalian cells and tissues.
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Affiliation(s)
- Marcos Roberto de Oliveira
- Department of Chemistry/ICET, Postgraduate Program in Chemistry (PPGQ), Federal University of Mato Grosso (UFMT), CEP, Cuiaba, MT, Brazil
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29
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Korshavn KJ, Jang M, Kwak YJ, Kochi A, Vertuani S, Bhunia A, Manfredini S, Ramamoorthy A, Lim MH. Reactivity of Metal-Free and Metal-Associated Amyloid-β with Glycosylated Polyphenols and Their Esterified Derivatives. Sci Rep 2015; 5:17842. [PMID: 26657338 PMCID: PMC4674742 DOI: 10.1038/srep17842] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Accepted: 11/05/2015] [Indexed: 12/19/2022] Open
Abstract
Both amyloid-β (Aβ) and transition metal ions are shown to be involved in the pathogenesis of Alzheimer's disease (AD), though the importance of their interactions remains unclear. Multifunctional molecules, which can target metal-free and metal-bound Aβ and modulate their reactivity (e.g., Aβ aggregation), have been developed as chemical tools to investigate their function in AD pathology; however, these compounds generally lack specificity or have undesirable chemical and biological properties, reducing their functionality. We have evaluated whether multiple polyphenolic glycosides and their esterified derivatives can serve as specific, multifunctional probes to better understand AD. The ability of these compounds to interact with metal ions and metal-free/-associated Aβ, and further control both metal-free and metal-induced Aβ aggregation was investigated through gel electrophoresis with Western blotting, transmission electron microscopy, UV-Vis spectroscopy, fluorescence spectroscopy, and NMR spectroscopy. We also examined the cytotoxicity of the compounds and their ability to mitigate the toxicity induced by both metal-free and metal-bound Aβ. Of the polyphenols investigated, the natural product (Verbascoside) and its esterified derivative (VPP) regulate the aggregation and cytotoxicity of metal-free and/or metal-associated Aβ to different extents. Our studies indicate Verbascoside represents a promising structure for further multifunctional tool development against both metal-free Aβ and metal-Aβ.
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Affiliation(s)
- Kyle J. Korshavn
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Milim Jang
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
| | - Yeon Ju Kwak
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
| | - Akiko Kochi
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
| | - Silvia Vertuani
- Department of Life Sciences and Biotechnology, University of Ferrara, I-44121 Ferrara, Italy
| | - Anirban Bhunia
- Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VII(M), Kolkata 700054, India
| | - Stefano Manfredini
- Department of Life Sciences and Biotechnology, University of Ferrara, I-44121 Ferrara, Italy
| | - Ayyalusamy Ramamoorthy
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
- Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Mi Hee Lim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
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30
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Williams TL, Urbanc B, Marshall KE, Vadukul DM, Jenkins ATA, Serpell LC. Europium as an inhibitor of Amyloid-β(1-42) induced membrane permeation. FEBS Lett 2015; 589:3228-36. [PMID: 26450778 PMCID: PMC4641243 DOI: 10.1016/j.febslet.2015.09.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 09/16/2015] [Accepted: 09/25/2015] [Indexed: 11/25/2022]
Abstract
Europium ions complex with GM1 gangliosides in phospholipid membranes. Europium ions cause inhibition Aβ–membrane interactions. Europium blocks an Aβ receptor protecting against membrane permeation. Discrete Aβ binding events correlate to specific membrane permeation events.
Soluble Amyloid-beta (Aβ) oligomers are a source of cytotoxicity in Alzheimer’s disease (AD). The toxicity of Aβ oligomers may arise from their ability to interact with and disrupt cellular membranes mediated by GM1 ganglioside receptors within these membranes. Therefore, inhibition of Aβ–membrane interactions could provide a means of preventing the toxicity associated with Aβ. Here, using Surface Plasmon field-enhanced Fluorescence Spectroscopy, we determine that the lanthanide, Europium III chloride (Eu3+), strongly binds to GM1 ganglioside-containing membranes and prevents the interaction with Aβ42 leading to a loss of the peptides ability to cause membrane permeation. Here we discuss the molecular mechanism by which Eu3+ inhibits Aβ42-membrane interactions and this may lead to protection of membrane integrity against Aβ42 induced toxicity.
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Affiliation(s)
- Thomas L Williams
- School of Life Sciences, University of Sussex, Falmer, East Sussex BN1 9QG, UK; Physics Department, Drexel University, Philadelphia, PA 19104, USA; School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Brigita Urbanc
- Physics Department, Drexel University, Philadelphia, PA 19104, USA
| | - Karen E Marshall
- School of Life Sciences, University of Sussex, Falmer, East Sussex BN1 9QG, UK
| | - Devkee M Vadukul
- School of Life Sciences, University of Sussex, Falmer, East Sussex BN1 9QG, UK
| | | | - Louise C Serpell
- School of Life Sciences, University of Sussex, Falmer, East Sussex BN1 9QG, UK.
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31
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Mishra P, Ayyannan SR, Panda G. Perspectives on Inhibiting β-Amyloid Aggregation through Structure-Based Drug Design. ChemMedChem 2015; 10:1467-74. [DOI: 10.1002/cmdc.201500215] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 06/30/2015] [Indexed: 12/24/2022]
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32
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Bhowmik D, Das AK, Maiti S. Rapid, cell-free assay for membrane-active forms of amyloid-β. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:4049-4053. [PMID: 25310376 DOI: 10.1021/la502679t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Small oligomers of amyloid beta (Aβ) are suspected to be the key to Alzheimer's disease (AD). However, identifying these toxic species in the background of other similar but nontoxic Aβ aggregates has remained a challenge. Recent studies indicate that Aβ undergoes a global structural transition in an early step of aggregation. This transition is marked by a strong increase in its affinity for cell membranes, which suggests that the resultant oligomers could be the key to Aβ toxicity. Here we use this increased membrane affinity to develop a rapid, quantitative, cell-free assay for these bioactive oligomers. It uses fluorescence correlation spectroscopy of fluorescently labeled Aβ and requires only 30 s of measurement time. We also describe a simpler (though less rapid) assay based on the same principles, which uses a dialysis step followed by conventional fluorescence spectroscopy. Our results potentially provide a much-needed high-throughput assay for AD drug development.
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Affiliation(s)
- Debanjan Bhowmik
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Anand Kant Das
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Sudipta Maiti
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
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33
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Tofoleanu F, Brooks BR, Buchete NV. Modulation of Alzheimer's Aβ protofilament-membrane interactions by lipid headgroups. ACS Chem Neurosci 2015; 6:446-55. [PMID: 25581460 DOI: 10.1021/cn500277f] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The molecular pathogenesis of Alzheimer's disease (AD) is complex and sparsely understood. The relationship between AD's amyloid β (Aβ) peptides and neuronal membranes is central to Aβ's cytotoxicity and is directly modulated by the composition of the lipid headgroups. Molecular studies of the insertion of model Aβ40 protofilaments in lipid bilayers revealed strong interactions that affect the structural integrity of both the membranes and the ordered amyloid aggregates. In particular, electrostatics plays a crucial role in the interaction between Aβ protofilaments and palmytoil-oleoyl-phosphatidylethanolamine (POPE) lipids, a common component of neuronal plasma membranes. Here, we use all-atom molecular dynamics and steered molecular dynamics simulations to systematically compare the effects that POPE and palmytoil-oleoyl-phosphatidylcholine (POPC) headgroups have on the Aβ-lipid interactions. We find that Aβ protofilaments exhibit weaker electrostatic interactions with POPC headgroups and establish significantly shorter-lived contacts with the POPC bilayer. This illustrates the crucial yet complex role of electrostatic and hydrogen bonding interactions in modulating the anchoring and insertion of Aβ peptides into lipid bilayers. Our study reveals the atomistic details behind the barrier created by the lipid headgroup region in impeding solution-aggregated fibrillar oligomers to spontaneously insert into POPC bilayers, in contrast to the POPE case. While the biological reality is notoriously more complex (e.g., including other factors such as cholesterol), our results evidence a simple experimentally and computationally testable case for probing the factors that control the insertion of Aβ oligomeric aggregates in neuronal cell membranes--a process central to their neurotoxicity.
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Affiliation(s)
- Florentina Tofoleanu
- Laboratory
of Computational Biology, Biochemistry and Biophysics Center, National
Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Bernard R. Brooks
- Laboratory
of Computational Biology, Biochemistry and Biophysics Center, National
Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Nicolae-Viorel Buchete
- School of Physics & Complex and Adaptive Systems Laboratory, University College Dublin, Belfield, Dublin 4, Ireland
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34
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Stancu IC, Vasconcelos B, Terwel D, Dewachter I. Models of β-amyloid induced Tau-pathology: the long and "folded" road to understand the mechanism. Mol Neurodegener 2014; 9:51. [PMID: 25407337 PMCID: PMC4255655 DOI: 10.1186/1750-1326-9-51] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 10/14/2014] [Indexed: 02/28/2023] Open
Abstract
The amyloid cascade hypothesis has been the prevailing hypothesis in Alzheimer’s Disease research, although the final and most wanted proof i.e. fully successful anti-amyloid clinical trials in patients, is still lacking. This may require a better in depth understanding of the cascade. Particularly, the exact toxic forms of Aβ and Tau, the molecular link between them and their respective contributions to the disease process need to be identified in detail. Although the lack of final proof has raised substantial criticism on the hypothesis per se, accumulating experimental evidence in in vitro models, in vivo models and from biomarkers analysis in patients supports the amyloid cascade and particularly Aβ-induced Tau-pathology, which is the focus of this review. We here discuss available models that recapitulate Aβ-induced Tau-pathology and review some potential underlying mechanisms. The availability and diversity of these models that mimic the amyloid cascade partially or more complete, provide tools to study remaining questions, which are crucial for development of therapeutic strategies for Alzheimer’s Disease.
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Affiliation(s)
| | | | | | - Ilse Dewachter
- Catholic University of Louvain, Institute of Neuroscience, Alzheimer Dementia, Av, E, Mounier 53, Av, Hippocrate 54, B-1200 Brussels, Belgium.
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35
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Venkatasubramaniam A, Drude A, Good T. Role of N-terminal residues in Aβ interactions with integrin receptor and cell surface. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2568-77. [DOI: 10.1016/j.bbamem.2014.06.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 05/26/2014] [Accepted: 06/13/2014] [Indexed: 01/12/2023]
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36
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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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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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38
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Cytotoxicity of intracellular aβ42 amyloid oligomers involves Ca2+ release from the endoplasmic reticulum by stimulated production of inositol trisphosphate. J Neurosci 2013; 33:3824-33. [PMID: 23447594 DOI: 10.1523/jneurosci.4367-12.2013] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Oligomeric forms of β-amyloid (Aβ(42)) peptides associated with Alzheimer's disease (AD) disrupt cellular Ca(2+) regulation by liberating Ca(2+) into the cytosol from both extracellular and intracellular sources. We elucidated the actions of intracellular Aβ by imaging Ca(2+) responses to injections of Aβ oligomers into Xenopus oocytes. Two types of signal were observed: (1) local, "channel-like" transients dependent on extracellular Ca(2+) influx, which resembled signals from amlyoid pores formed by extracellular application of oligomers; and (2) local transients and global Ca(2+) waves, resembling Ca(2+) puffs and waves mediated by inositol trisphosphate (IP(3)). The latter responses were suppressed by antagonists of the IP(3) receptor (caffeine and heparin), pretreatment with the G(i)(o)-protein inhibitor pertussis toxin, and pretreatment with lithium to deplete membrane inositol lipids. We show that G-protein-mediated stimulation of IP(3) production and consequent liberation of Ca(2+) from the endoplasmic reticulum by intracellular Aβ oligomers is cytotoxic, potentially representing a novel pathological mechanism in AD which may be further exacerbated by AD-linked mutations in presenilins to promote opening of IP(3) receptor/channels.
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Sarkar B, Das AK, Maiti S. Thermodynamically stable amyloid-β monomers have much lower membrane affinity than the small oligomers. Front Physiol 2013; 4:84. [PMID: 23781202 PMCID: PMC3681284 DOI: 10.3389/fphys.2013.00084] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 04/02/2013] [Indexed: 12/23/2022] Open
Abstract
Amyloid beta (Aβ) is an extracellular 39–43 residue long peptide present in the mammalian cerebrospinal fluid, whose aggregation is associated with Alzheimer's disease (AD). Small oligomers of Aβ are currently thought to be the key to toxicity. However, it is not clear why the monomers of Aβ are non-toxic, and at what stage of aggregation toxicity emerges. Interactions of Aβ with cell membranes is thought to be the initiator of toxicity, but membrane binding studies with different preparations of monomers and oligomers have not settled this issue. We have earlier found that thermodynamically stable Aβ monomers emerge spontaneously from oligomeric mixtures upon long term incubation in physiological solutions (Nag et al., 2011). Here we show that the membrane-affinity of these stable Aβ monomers is much lower than that of a mixture of monomers and small oligomers (containing dimers to decamers), providing a clue to the emergence of toxicity. Fluorescently labeled Aβ40 monomers show negligible binding to cell membranes of a neuronal cell line (RN46A) at physiological concentrations (250 nM), while oligomers at the same concentrations show strong binding within 30 min of incubation. The increased affinity most likely does not require any specific neuronal receptor, since this difference in membrane-affinity was also observed in a somatic cell-line (HEK 293T). Similar results are also obtained for Aβ42 monomers and oligomers. Minimal amount of cell death is observed at these concentrations even after 36 h of incubation. It is likely that membrane binding precedes subsequent slower toxic events induced by Aβ. Our results (a) provide an explanation for the non-toxic nature of Aβ monomers, (b) suggest that Aβ toxicity emerges at the initial oligomeric phase, and (c) provide a quick assay for monitoring the benign-to-toxic transformation of Aβ.
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Affiliation(s)
- Bidyut Sarkar
- Department of Chemical Sciences, Tata Institute of Fundamental Research Colaba, Mumbai, India
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40
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Xu P, Xu J, Liu S, Yang Z. Nano copper induced apoptosis in podocytes via increasing oxidative stress. JOURNAL OF HAZARDOUS MATERIALS 2012; 241-242:279-86. [PMID: 23063557 DOI: 10.1016/j.jhazmat.2012.09.041] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 08/31/2012] [Accepted: 09/17/2012] [Indexed: 05/07/2023]
Abstract
Nanosized copper particles (nano-Cu), one of the representative metal nanometer materials, were used in several domains, and the potential toxicity was raised more and more attention. In order to investigate the cytotoxicity induced by nano-Cu in podocytes, which was the key player of the glomerular filtration barrier, podocytes were treated with different concentrations of nano-Cu. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to measure the cell viability. Hoechst 33342 staining assay and Annexin V/PI double labeling assay were used to identify whether the cytotoxicity induced by nano-Cu was due to apoptosis or necrosis. The oxidative stress induced by nano-Cu and its mechanism were studied in relation to the generation of reactive oxygen species (ROS), superoxide dismutase (SOD) and malondialdehyde (MDA). As a result, while podocytes were treated with nano-Cu, the cell viability was significantly decreased and the apoptosis was significantly increased in podocytes. Results showed that nano-Cu affected the oxidant-antioxidant balance and had cytotoxicity in podocytes, resulting in the enhanced generation of ROS and MDA. Meanwhile, pretreatment with N-(2-mercaptopropionyl)-glycine (N-MPG), a type of ROS scavenger, could inhibit podocyte apoptosis induced by nano-Cu. Results suggested that the increased oxidative stress was a key mechanism in the podocyte apoptosis induced by nano-Cu, which could provide evidence for further research on the toxicity of nano-Cu.
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Affiliation(s)
- Pengjuan Xu
- College of Medicine, Nankai University, Tianjin 300071, China
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41
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Sinha S, Lopes DHJ, Bitan G. A key role for lysine residues in amyloid β-protein folding, assembly, and toxicity. ACS Chem Neurosci 2012; 3:473-81. [PMID: 22860216 DOI: 10.1021/cn3000247] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Accepted: 03/16/2012] [Indexed: 12/25/2022] Open
Abstract
A combination of hydrophobic and electrostatic interactions is important in initiating the aberrant self-assembly process that leads to formation of toxic oligomers and aggregates by multiple disease-related proteins, including amyloid β-protein (Aβ), whose self-assembly is believed to initiate brain pathogenesis in Alzheimer's disease. Lys residues play key roles in this process and participate in both types of interaction. They also are the target of our recently reported molecular tweezer inhibitors. To obtain further insight into the role of the two Lys residues in Aβ assembly and toxicity, here we substituted each by Ala in both Aβ40 and Aβ42 and studied the impact of the substitution on Aβ oligomerization, aggregation, and toxicity. Our data show that each substitution has a major impact on Aβ assembly and toxicity, with significant differences depending on peptide length (40 versus 42 amino acids) and the position of the substitution. In particular, Lys16→Ala substitution dramatically reduces Aβ toxicity. The data support the use of compounds targeting Lys residues specifically as inhibitors of Aβ toxicity and suggest that exploring the role of Lys residues in other disease-related amyloidogenic proteins may help understanding the mechanisms of aggregation and toxicity of these proteins.
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Affiliation(s)
- Sharmistha Sinha
- Department of Neurology, David Geffen School of Medicine, ‡Brain Research Institute, and §Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
| | - Dahabada H. J. Lopes
- Department of Neurology, David Geffen School of Medicine, ‡Brain Research Institute, and §Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
| | - Gal Bitan
- Department of Neurology, David Geffen School of Medicine, ‡Brain Research Institute, and §Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
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42
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Ta HP, Berthelot K, Coulary-Salin B, Castano S, Desbat B, Bonnafous P, Lambert O, Alves I, Cullin C, Lecomte S. A yeast toxic mutant of HET-s amyloid disrupts membrane integrity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2325-34. [PMID: 22562024 DOI: 10.1016/j.bbamem.2012.04.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 04/17/2012] [Accepted: 04/18/2012] [Indexed: 10/28/2022]
Abstract
Many studies have pointed out the interaction between amyloids and membranes, and their potential involvement in amyloid toxicity. Previously, we generated a yeast toxic amyloid mutant (M8) from the harmless amyloid protein by changing a few residues of the Prion Forming Domain of HET-s (PFD HET-s(218-289)) and clearly demonstrated the complete different behaviors of the non-toxic Wild Type (WT) and toxic amyloid (called M8) in terms of fiber morphology, aggregation kinetics and secondary structure. In this study, we compared the interaction of both proteins (WT and M8) with membrane models, as liposomes or supported bilayers. We first demonstrated that the toxic protein (M8) induces a significant leakage of liposomes formed with negatively charged lipids and promotes the formation of microdomains inside the lipid bilayer (as potential "amyloid raft"), whereas the non-toxic amyloid (WT) only binds to the membrane without further perturbations. The secondary structure of both amyloids interacting with membrane is preserved, but the anti-symmetric PO(2)(-) vibration is strongly shifted in the presence of M8. Secondly, we established that the presence of membrane models catalyzes the amyloidogenesis of both proteins. Cryo-TEM (cryo-transmission electron microscopy) images show the formation of long HET-s fibers attached to liposomes, whereas a large aggregation of the toxic M8 seems to promote a membrane disruption. This study allows us to conclude that the toxicity of the M8 mutant could be due to its high propensity to interact and disrupt lipid membranes.
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Affiliation(s)
- Ha Phuong Ta
- Université Bordeaux 1, Allée Geoffroy de Saint Hilaire, Pessac, France
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43
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Hunter S, Brayne C. Relationships between the amyloid precursor protein and its various proteolytic fragments and neuronal systems. Alzheimers Res Ther 2012; 4:10. [PMID: 22498202 PMCID: PMC3583130 DOI: 10.1186/alzrt108] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease and in its familial form is associated with mutations in the amyloid precursor protein (APP) and the presenilins (PSs). Much data regarding the interactions of APP, its proteolytic fragments and PS have been generated, expanding our understanding of the roles of these proteins in mechanisms underlying cognitive function and revealing many complex relationships with wide ranging cellular systems. In this review, we examine the multiple interactions of APP and its proteolytic fragments with other neuronal systems in terms of feedback loops and use these relationships to build a map. We highlight the complexity involved in the APP proteolytic system and discuss alternative perspectives on the roles of APP and its proteolytic fragments in dynamic processes associated with disease progression in AD. We highlight areas where data are missing and suggest potential confounding factors. We suggest that a systems biology approach enhances representations of the data and may be more useful in modelling both normal cognition and disease processes.
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Affiliation(s)
- Sally Hunter
- Institute of Public Health, University of Cambridge, Forvie site, Robinson Way, Cambridge CB2 0SR, UK
| | - Carol Brayne
- Institute of Public Health, University of Cambridge, Forvie site, Robinson Way, Cambridge CB2 0SR, UK
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Lü L, Zhang L, Wai MSM, Yew DTW, Xu J. Exocytosis of MTT formazan could exacerbate cell injury. Toxicol In Vitro 2012; 26:636-44. [PMID: 22401948 DOI: 10.1016/j.tiv.2012.02.006] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Revised: 10/29/2011] [Accepted: 02/20/2012] [Indexed: 01/01/2023]
Abstract
MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] method is one of the most widely used methods to analyze cell proliferation and viability. It is taken up through endocytosis and is reduced by mitochondrial enzymes as well as endosomal/lysosomal compartments, then is transported to cell surfaces to form needle-like MTT formazans; however the effect of MTT itself still remains elusive. Our objective was to investigate the direct effects of MTT on in vitro SH-SY5Y cells. Results showed that the endocytosis of MTT did not cause obvious lesion and induce cell death, but the metabolism and exocytosis of MTT could dramatically damage cells. Our results also indicated that MTT could activate apoptosis related factors such as caspase-8, caspase-3 or accelerate the leakage of cell contents after the appearance of MTT formazan crystals. The present data suggest MTT method should be carefully chosen; otherwise the cell viability would be underestimated and incomparable.
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Affiliation(s)
- Lanhai Lü
- Department of Anatomy, Zhongshan School of Medicine, Sun Yat-sen University, Northern Campus, Guangzhou, Guangdong, China
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45
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Tofoleanu F, Buchete NV. Molecular interactions of Alzheimer's Aβ protofilaments with lipid membranes. J Mol Biol 2012; 421:572-86. [PMID: 22281438 DOI: 10.1016/j.jmb.2011.12.063] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Revised: 12/22/2011] [Accepted: 12/29/2011] [Indexed: 12/22/2022]
Abstract
Amyloid fibrils and peptide oligomers play central roles in the pathology of Alzheimer's disease, type 2 diabetes, Parkinson's disease, Huntington's disease, and prion-related disease. Here, we investigate the molecular interactions between preformed amyloid β (Aβ) molecular protofilaments and lipid bilayer membranes, in the presence of explicit water molecules, using computational models and all-atom molecular dynamics. These interactions play an important role in the stability and function of both Aβ fibrils and the adjacent cellular membrane. Taking advantage of the symmetry-related and directional properties of the protofilaments, we build models that cover several relative protofilament-membrane orientations. Our molecular dynamics simulations reveal the relative contributions of different structural elements to the dynamics and stability of Aβ protofilament segments near membranes, and the first steps in the mechanism of fibril-membrane interactions. During this process, we observe a significant alteration of the side-chain contact pattern in protofilaments, although a fraction of the characteristic β-sheet content is preserved. As a major driving force, we identify the electrostatic interactions between Aβ charged side chains, including E22, D23, and K28, and lipid headgroups. Together with hydrogen bonding with atoms from lipid headgroups, these interactions can facilitate the penetration of hydrophobic C-terminal amino acids through the lipid headgroup region, which can finally lead both to further loss of the initial fibril structure and to local membrane-thinning effects. Our results may guide new experiments that could test the extent to which the structural features of water-formed amyloid fibrils are preserved, lost, or reshaped by membrane-mediated interactions.
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Härd T, Lendel C. Inhibition of amyloid formation. J Mol Biol 2012; 421:441-65. [PMID: 22244855 DOI: 10.1016/j.jmb.2011.12.062] [Citation(s) in RCA: 215] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 12/28/2011] [Accepted: 12/29/2011] [Indexed: 12/26/2022]
Abstract
Amyloid is aggregated protein in the form of insoluble fibrils. Amyloid deposition in human tissue-amyloidosis-is associated with a number of diseases including all common dementias and type II diabetes. Considerable progress has been made to understand the mechanisms leading to amyloid formation. It is, however, not yet clear by which mechanisms amyloid and protein aggregates formed on the path to amyloid are cytotoxic. Strategies to prevent protein aggregation and amyloid formation are nevertheless, in many cases, promising and even successful. This review covers research on intervention of amyloidosis and highlights several examples of how inhibition of protein aggregation and amyloid formation has been achieved in practice. For instance, rational design can provide drugs that stabilize a native folded state of a protein, protein engineering can provide new binding proteins that sequester monomeric peptides from aggregation, small molecules and peptides can be designed to block aggregation or direct it into non-cytotoxic paths, and monoclonal antibodies have been developed for therapies towards neurodegenerative diseases based on inhibition of amyloid formation and clearance.
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Affiliation(s)
- Torleif Härd
- Department of Molecular Biology, Swedish University of Agricultural Sciences, SE-751 24 Uppsala, Sweden.
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Demuro A, Smith M, Parker I. Single-channel Ca(2+) imaging implicates Aβ1-42 amyloid pores in Alzheimer's disease pathology. ACTA ACUST UNITED AC 2011; 195:515-24. [PMID: 22024165 PMCID: PMC3206345 DOI: 10.1083/jcb.201104133] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
High-resolution imaging of calcium influx reveals that the Aβ peptides implicated in Alzheimer’s disease form highly toxic Ca2+-permeable pores. Oligomeric forms of Aβ peptides are implicated in Alzheimer’s disease (AD) and disrupt membrane integrity, leading to cytosolic calcium (Ca2+) elevation. Proposed mechanisms by which Aβ mediates its effects include lipid destabilization, activation of native membrane channels, and aggregation of Aβ into Ca2+-permeable pores. We distinguished between these using total internal reflection fluorescence (TIRF) microscopy to image Ca2+ influx in Xenopus laevis oocytes. Aβ1–42 oligomers evoked single-channel Ca2+ fluorescence transients (SCCaFTs), which resembled those from classical ion channels but which were not attributable to endogenous oocyte channels. SCCaFTs displayed widely variable open probabilities (Po) and stepwise transitions among multiple amplitude levels reminiscent of subconductance levels of ion channels. The proportion of high Po, large amplitude SCCaFTs grew with time, suggesting that continued oligomer aggregation results in the formation of highly toxic pores. We conclude that formation of intrinsic Ca2+-permeable membrane pores is a major pathological mechanism in AD and introduce TIRF imaging for massively parallel single-channel studies of the incorporation, assembly, and properties of amyloidogenic oligomers.
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Affiliation(s)
- Angelo Demuro
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA 92697, USA.
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Torrent M, Valle J, Nogués MV, Boix E, Andreu D. The generation of antimicrobial peptide activity: a trade-off between charge and aggregation? Angew Chem Int Ed Engl 2011; 50:10686-9. [PMID: 21928454 DOI: 10.1002/anie.201103589] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Indexed: 12/11/2022]
Affiliation(s)
- Marc Torrent
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Dr. Aiguader 88, 08003 Barcelona, Spain
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49
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Torrent M, Valle J, Nogués MV, Boix E, Andreu D. The Generation of Antimicrobial Peptide Activity: A Trade-off between Charge and Aggregation? Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201103589] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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50
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Fonte V, Dostal V, Roberts CM, Gonzales P, Lacor PN, Lacor P, Velasco PT, Magrane J, Dingwell N, Fan EY, Silverman MA, Stein GH, Link CD. A glycine zipper motif mediates the formation of toxic β-amyloid oligomers in vitro and in vivo. Mol Neurodegener 2011; 6:61. [PMID: 21861874 PMCID: PMC3178497 DOI: 10.1186/1750-1326-6-61] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 08/23/2011] [Indexed: 12/21/2022] Open
Abstract
Background The β-amyloid peptide (Aβ) contains a Gly-XXX-Gly-XXX-Gly motif in its C-terminal region that has been proposed to form a "glycine zipper" that drives the formation of toxic Aβ oligomers. We have tested this hypothesis by examining the toxicity of Aβ variants containing substitutions in this motif using a neuronal cell line, primary neurons, and a transgenic C. elegans model. Results We found that a Gly37Leu substitution dramatically reduced Aβ toxicity in all models tested, as measured by cell dysfunction, cell death, synaptic alteration, or tau phosphorylation. We also demonstrated in multiple models that Aβ Gly37Leu is actually anti-toxic, thereby supporting the hypothesis that interference with glycine zipper formation blocks assembly of toxic Aβ oligomers. To test this model rigorously, we engineered second site substitutions in Aβ predicted by the glycine zipper model to compensate for the Gly37Leu substitution and expressed these in C. elegans. We show that these second site substitutions restore in vivo Aβtoxicity, further supporting the glycine zipper model. Conclusions Our structure/function studies support the view that the glycine zipper motif present in the C-terminal portion of Aβ plays an important role in the formation of toxic Aβ oligomers. Compounds designed to interfere specifically with formation of the glycine zipper could have therapeutic potential.
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Affiliation(s)
- Virginia Fonte
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80309, USA.
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