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Marshall KE, Mengham K, Spink MC, Vania L, Pollard HJ, Darrow MC, Duke E, Harkiolaki M, Serpell LC. Correlative cryo-soft X-ray tomography and cryo-structured illumination microscopy reveal changes to lysosomes in amyloid-β-treated neurons. Structure 2024; 32:585-593.e3. [PMID: 38471506 DOI: 10.1016/j.str.2024.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/20/2023] [Accepted: 02/15/2024] [Indexed: 03/14/2024]
Abstract
Protein misfolding is common to neurodegenerative diseases (NDs) including Alzheimer's disease (AD), which is partly characterized by the self-assembly and accumulation of amyloid-beta in the brain. Lysosomes are a critical component of the proteostasis network required to degrade and recycle material from outside and within the cell and impaired proteostatic mechanisms have been implicated in NDs. We have previously established that toxic amyloid-beta oligomers are endocytosed, accumulate in lysosomes, and disrupt the endo-lysosomal system in neurons. Here, we use pioneering correlative cryo-structured illumination microscopy and cryo-soft X-ray tomography imaging techniques to reconstruct 3D cellular architecture in the native state revealing reduced X-ray density in lysosomes and increased carbon dense vesicles in oligomer treated neurons compared with untreated cells. This work provides unprecedented visual information on the changes to neuronal lysosomes inflicted by amyloid beta oligomers using advanced methods in structural cell biology.
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Affiliation(s)
- Karen E Marshall
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, BN1 9QG Brighton, UK.
| | - Kurtis Mengham
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, BN1 9QG Brighton, UK
| | - Matthew C Spink
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Fermi Avenue, OX11 0DE Didcot, UK
| | - Lyra Vania
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, BN1 9QG Brighton, UK
| | - Hannah Jane Pollard
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, BN1 9QG Brighton, UK
| | - Michele C Darrow
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Fermi Avenue, OX11 0DE Didcot, UK
| | - Elizabeth Duke
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Fermi Avenue, OX11 0DE Didcot, UK
| | - Maria Harkiolaki
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Fermi Avenue, OX11 0DE Didcot, UK
| | - Louise C Serpell
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, BN1 9QG Brighton, UK.
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2
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Frieg B, Han M, Giller K, Dienemann C, Riedel D, Becker S, Andreas LB, Griesinger C, Schröder GF. Cryo-EM structures of lipidic fibrils of amyloid-β (1-40). Nat Commun 2024; 15:1297. [PMID: 38351005 PMCID: PMC10864299 DOI: 10.1038/s41467-023-43822-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 11/21/2023] [Indexed: 02/16/2024] Open
Abstract
Alzheimer's disease (AD) is a progressive and incurable neurodegenerative disease characterized by the extracellular deposition of amyloid plaques. Investigation into the composition of these plaques revealed a high amount of amyloid-β (Aβ) fibrils and a high concentration of lipids, suggesting that fibril-lipid interactions may also be relevant for the pathogenesis of AD. Therefore, we grew Aβ40 fibrils in the presence of lipid vesicles and determined their structure by cryo-electron microscopy (cryo-EM) to high resolution. The fold of the major polymorph is similar to the structure of brain-seeded fibrils reported previously. The majority of the lipids are bound to the fibrils, as we show by cryo-EM and NMR spectroscopy. This apparent lipid extraction from vesicles observed here in vitro provides structural insights into potentially disease-relevant fibril-lipid interactions.
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Affiliation(s)
- Benedikt Frieg
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry) and JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, Jülich, Germany
| | - Mookyoung Han
- Department of NMR-Based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Karin Giller
- Department of NMR-Based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Christian Dienemann
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Dietmar Riedel
- Laboratory of Electron Microscopy, Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Stefan Becker
- Department of NMR-Based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
| | - Loren B Andreas
- Department of NMR-Based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
| | - Christian Griesinger
- Department of NMR-Based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
- Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.
| | - Gunnar F Schröder
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry) and JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, Jülich, Germany.
- Physics Department, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
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3
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Nie RZ, Zhang SS, Yan XK, Feng K, Lao YJ, Bao YR. Molecular insights into the structure destabilization effects of ECG and EC on the Aβ protofilament: An all-atom molecular dynamics simulation study. Int J Biol Macromol 2023; 253:127002. [PMID: 37729983 DOI: 10.1016/j.ijbiomac.2023.127002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 09/13/2023] [Accepted: 09/17/2023] [Indexed: 09/22/2023]
Abstract
The formation of Aβ into amyloid fibrils was closely connected to AD, therefore, the Aβ aggregates were the primary therapeutic targets against AD. Previous studies demonstrated that epicatechin-3-gallate (ECG), which possessed a gallate moiety, exhibited a greater ability to disrupt the preformed Aβ amyloid fibrils than epicatechin (EC), indicating that the gallate moiety was crucial. In the present study, the molecular mechanisms were investigated. Our results demonstrated that ECG had more potent disruptive impacts on the β-sheet structure and K28-A42 salt bridges than EC. We found that ECG significantly interfered the interactions between Peptide-4 and Peptide-5. However, EC could not. The disruption of K28-A42 salt bridges by ECG was mainly due to the interactions between ECG and the hydrophobic residues located at C-terminus. Interestingly, EC disrupted the K28-A42 salt bridges by the interactions with C-terminal hydrophobic residues and the cation-π interactions with K28. Moreover, our results indicated that hydrophobic interactions, H-bonds, π-π interactions and cation-π interactions between ECG and the bend of L-shaped region caused the disaggregation of interactions between Peptide-4 and Peptide-5. Significantly, gallate moiety in ECG had contributed tremendously to the disaggregation. We believed that our findings could be useful for designing prospective drug candidates targeting AD.
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Affiliation(s)
- Rong-Zu Nie
- College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450002, China; Henan Key Laboratory of Cold Chain Food Quality and Safety Control, Zhengzhou University of Light Industry, Zhengzhou 450002, China
| | - Shan-Shuo Zhang
- College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450002, China
| | - Xiao-Ke Yan
- College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450002, China
| | - Kun Feng
- College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450002, China; Henan Key Laboratory of Cold Chain Food Quality and Safety Control, Zhengzhou University of Light Industry, Zhengzhou 450002, China
| | - Yan-Jing Lao
- College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450002, China
| | - Ya-Ru Bao
- Science and Technology Division, Zhengzhou University of Light Industry, Zhengzhou 450002, China.
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4
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Santhanam V, Modi P, Mishra UK, Jahan I, Ramesh NG, Deep S. Rational design and synthesis of novel triazole- and tetrazole-fused iminosugars as potential inhibitors of amyotrophic lateral sclerosis (ALS) linked SOD1 aggregation. Int J Biol Macromol 2023; 253:126900. [PMID: 37714236 DOI: 10.1016/j.ijbiomac.2023.126900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 08/25/2023] [Accepted: 09/12/2023] [Indexed: 09/17/2023]
Abstract
In this manuscript we report the first example of an iminosugar that inhibits superoxide dismutase fibrillation associated with the amyotrophic lateral sclerosis (ALS). The present work involves synthesis of novel triazole and tetrazole embedded iminosugars, synthesized in 11-13 high yielding steps starting from readily available tri-O-benzyl-D-glucal and proceeding through a concomitant azidation - thermal intramolecular [3 + 2] cycloaddition reaction as the key step. One of these pre-designed iminosugars was found to inhibit fibrillation of SOD1 and also has shown propensity to break pre-formed fibrils. Docking and MD simulation studies suggest that the most probable interaction of this compound is a hydrogen bonding with Arg69, a loop IV residue of SOD1, which has a crucial role in stabilizing the native conformation of SOD1.
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Affiliation(s)
- Venkatesan Santhanam
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Priya Modi
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Umesh K Mishra
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Ishrat Jahan
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Namakkal G Ramesh
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
| | - Shashank Deep
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
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5
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Sallaberry CA, Voss BJ, Stone WB, Estrada F, Bhatia A, Soto JD, Griffin CW, Vander Zanden CM. Curcumin Reduces Amyloid Beta Oligomer Interactions with Anionic Membranes. ACS Chem Neurosci 2023; 14:4026-4038. [PMID: 37906715 DOI: 10.1021/acschemneuro.3c00512] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023] Open
Abstract
Many neurodegenerative diseases involve amyloidogenic proteins forming surface-bound aggregates on anionic membranes, and the peptide amyloid β (Aβ) in Alzheimer's disease is one prominent example of this. Curcumin is a small polyphenolic molecule that provides an interesting opportunity to understand the fundamental mechanisms of membrane-mediated aggregation because it embeds into membranes to alter their structure while also altering Aβ aggregation in an aqueous environment. The purpose of this work was to understand interactions among curcumin, β-sheet-rich Aβ fibrillar oligomers (FO), and a model anionic membrane. From a combination of liquid surface X-ray scattering experiments and molecular dynamics simulations, we found that curcumin embedded into an anionic 1,2-dimyristoyl-sn-glycero-3-phosphorylglycerol (DMPG) membrane to rest between the lipid headgroups and the tails, causing disorder and membrane thinning. FO accumulation on the membrane was reduced by ∼66% in the presence of curcumin, likely influenced by membrane thinning. Simulation results suggested curcumin clusters near exposed phenylalanine residues on a membrane-embedded FO structure. Altogether, curcumin inhibited FO interactions with a DMPG membrane, likely through a combination of altered membrane structure and interactions with the FO surface. This work elucidates the mechanism of curcumin as a small molecule that inhibits amyloidogenesis through a combination of both membrane and protein interactions.
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Affiliation(s)
- Chad A Sallaberry
- Department of Chemistry and Biochemistry, University of Colorado Colorado Springs, Colorado Springs, Colorado 80918, United States
| | - Barbie J Voss
- Department of Chemistry and Biochemistry, University of Colorado Colorado Springs, Colorado Springs, Colorado 80918, United States
| | - William B Stone
- Department of Chemistry and Biochemistry, University of Colorado Colorado Springs, Colorado Springs, Colorado 80918, United States
| | - Fabiola Estrada
- Department of Chemistry and Biochemistry, University of Colorado Colorado Springs, Colorado Springs, Colorado 80918, United States
| | - Advita Bhatia
- Department of Chemistry and Biochemistry, University of Colorado Colorado Springs, Colorado Springs, Colorado 80918, United States
| | - J Daniel Soto
- Department of Chemistry and Biochemistry, University of Colorado Colorado Springs, Colorado Springs, Colorado 80918, United States
| | - Charles W Griffin
- Department of Chemistry and Biochemistry, University of Colorado Colorado Springs, Colorado Springs, Colorado 80918, United States
| | - Crystal M Vander Zanden
- Department of Chemistry and Biochemistry, University of Colorado Colorado Springs, Colorado Springs, Colorado 80918, United States
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6
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Rudajev V, Novotny J. Cholesterol-dependent amyloid β production: space for multifarious interactions between amyloid precursor protein, secretases, and cholesterol. Cell Biosci 2023; 13:171. [PMID: 37705117 PMCID: PMC10500844 DOI: 10.1186/s13578-023-01127-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 09/05/2023] [Indexed: 09/15/2023] Open
Abstract
Amyloid β is considered a key player in the development and progression of Alzheimer's disease (AD). Many studies investigating the effect of statins on lowering cholesterol suggest that there may be a link between cholesterol levels and AD pathology. Since cholesterol is one of the most abundant lipid molecules, especially in brain tissue, it affects most membrane-related processes, including the formation of the most dangerous form of amyloid β, Aβ42. The entire Aβ production system, which includes the amyloid precursor protein (APP), β-secretase, and the complex of γ-secretase, is highly dependent on membrane cholesterol content. Moreover, cholesterol can affect amyloidogenesis in many ways. Cholesterol influences the stability and activity of secretases, but also dictates their partitioning into specific cellular compartments and cholesterol-enriched lipid rafts, where the amyloidogenic machinery is predominantly localized. The most complicated relationships have been found in the interaction between cholesterol and APP, where cholesterol affects not only APP localization but also the precise character of APP dimerization and APP processing by γ-secretase, which is important for the production of Aβ of different lengths. In this review, we describe the intricate web of interdependence between cellular cholesterol levels, cholesterol membrane distribution, and cholesterol-dependent production of Aβ, the major player in AD.
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Affiliation(s)
- Vladimir Rudajev
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jiri Novotny
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
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7
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Viles JH. Imaging Amyloid-β Membrane Interactions: Ion-Channel Pores and Lipid-Bilayer Permeability in Alzheimer's Disease. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 135:e202215785. [PMID: 38515735 PMCID: PMC10952214 DOI: 10.1002/ange.202215785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Indexed: 03/08/2023]
Abstract
The accumulation of the amyloid-β peptides (Aβ) is central to the development of Alzheimer's disease. The mechanism by which Aβ triggers a cascade of events that leads to dementia is a topic of intense investigation. Aβ self-associates into a series of complex assemblies with different structural and biophysical properties. It is the interaction of these oligomeric, protofibril and fibrillar assemblies with lipid membranes, or with membrane receptors, that results in membrane permeability and loss of cellular homeostasis, a key event in Alzheimer's disease pathology. Aβ can have an array of impacts on lipid membranes, reports have included: a carpeting effect; a detergent effect; and Aβ ion-channel pore formation. Recent advances imaging these interactions are providing a clearer picture of Aβ induced membrane disruption. Understanding the relationship between different Aβ structures and membrane permeability will inform therapeutics targeting Aβ cytotoxicity.
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Affiliation(s)
- John H. Viles
- Department of Biochemistry, SBBS, Queen MaryUniversity of LondonUK
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8
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Viles JH. Imaging Amyloid-β Membrane Interactions: Ion-Channel Pores and Lipid-Bilayer Permeability in Alzheimer's Disease. Angew Chem Int Ed Engl 2023; 62:e202215785. [PMID: 36876912 PMCID: PMC10953358 DOI: 10.1002/anie.202215785] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/07/2023]
Abstract
The accumulation of the amyloid-β peptides (Aβ) is central to the development of Alzheimer's disease. The mechanism by which Aβ triggers a cascade of events that leads to dementia is a topic of intense investigation. Aβ self-associates into a series of complex assemblies with different structural and biophysical properties. It is the interaction of these oligomeric, protofibril and fibrillar assemblies with lipid membranes, or with membrane receptors, that results in membrane permeability and loss of cellular homeostasis, a key event in Alzheimer's disease pathology. Aβ can have an array of impacts on lipid membranes, reports have included: a carpeting effect; a detergent effect; and Aβ ion-channel pore formation. Recent advances imaging these interactions are providing a clearer picture of Aβ induced membrane disruption. Understanding the relationship between different Aβ structures and membrane permeability will inform therapeutics targeting Aβ cytotoxicity.
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Affiliation(s)
- John H. Viles
- Department of Biochemistry, SBBS, Queen MaryUniversity of LondonUK
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9
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Saha J, Bose P, Dhakal S, Ghosh P, Rangachari V. Ganglioside-Enriched Phospholipid Vesicles Induce Cooperative Aβ Oligomerization and Membrane Disruption. Biochemistry 2022; 61:2206-2220. [PMID: 36173882 PMCID: PMC9840156 DOI: 10.1021/acs.biochem.2c00495] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
A major hallmark of Alzheimer's disease (AD) is the accumulation of extracellular aggregates of amyloid-β (Aβ). Structural polymorphism observed among Aβ fibrils in AD brains seem to correlate with the clinical subtypes suggesting a link between fibril polymorphism and pathology. Since fibrils emerge from a templated growth of low-molecular-weight oligomers, understanding the factors affecting oligomer generation is important. Membrane lipids are key factors to influence early stages of Aβ aggregation and oligomer generation, which cause membrane disruption. We have previously demonstrated that conformationally discrete Aβ oligomers can be generated by modulating the charge, composition, and chain length of lipids and surfactants. Here, we extend our studies into liposomal models by investigating Aβ oligomerization on large unilamellar vesicles (LUVs) of total brain extracts (TBE), reconstituted lipid rafts (LRs), or 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). Varying the vesicle composition by specifically increasing the amount of GM1 gangliosides as a constituent, we found that only GM1-enriched liposomes induce the formation of toxic, low-molecular-weight oligomers. Furthermore, we found that the aggregation on liposome surface and membrane disruption are highly cooperative and sensitive to membrane surface characteristics. Numerical simulations confirm such a cooperativity and reveal that GM1-enriched liposomes form twice as many pores as those formed in the absence GM1. Overall, this study uncovers mechanisms of cooperativity between oligomerization and membrane disruption under controlled lipid compositional bias, and refocuses the significance of the early stages of Aβ aggregation in polymorphism, propagation, and toxicity in AD.
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Affiliation(s)
- Jhinuk Saha
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg, Mississippi 39406, United States
| | - Priyankar Bose
- Department of Computer Science, Virginia Commonwealth University, Richmond, Virginia 23220, United States
| | - Shailendra Dhakal
- Center for Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg, Mississippi 39406, United States
| | - Preetam Ghosh
- Department of Computer Science, Virginia Commonwealth University, Richmond, Virginia 23220, United States
| | - Vijayaraghavan Rangachari
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg, Mississippi 39406, United States; Center for Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg, Mississippi 39406, United States
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10
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Rudajev V, Novotny J. Cholesterol as a key player in amyloid β-mediated toxicity in Alzheimer’s disease. Front Mol Neurosci 2022; 15:937056. [PMID: 36090253 PMCID: PMC9453481 DOI: 10.3389/fnmol.2022.937056] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 07/27/2022] [Indexed: 11/13/2022] Open
Abstract
Alzheimer’s disease (AD) is a neurodegenerative disorder that is one of the most devastating and widespread diseases worldwide, mainly affecting the aging population. One of the key factors contributing to AD-related neurotoxicity is the production and aggregation of amyloid β (Aβ). Many studies have shown the ability of Aβ to bind to the cell membrane and disrupt its structure, leading to cell death. Because amyloid damage affects different parts of the brain differently, it seems likely that not only Aβ but also the nature of the membrane interface with which the amyloid interacts, helps determine the final neurotoxic effect. Because cholesterol is the dominant component of the plasma membrane, it plays an important role in Aβ-induced toxicity. Elevated cholesterol levels and their regulation by statins have been shown to be important factors influencing the progression of neurodegeneration. However, data from many studies have shown that cholesterol has both neuroprotective and aggravating effects in relation to the development of AD. In this review, we attempt to summarize recent findings on the role of cholesterol in Aβ toxicity mediated by membrane binding in the pathogenesis of AD and to consider it in the broader context of the lipid composition of cell membranes.
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Kalita S, Kalita S, Kawa AH, Shill S, Gupta A, Kumar S, Mandal B. Copper Chelating Cyclic Peptidomimetic Inhibits Aβ Fibrillogenesis. RSC Med Chem 2022; 13:761-774. [PMID: 35814930 PMCID: PMC9215124 DOI: 10.1039/d2md00019a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 05/09/2022] [Indexed: 11/21/2022] Open
Abstract
Misfolding of amyloid- peptide (A) and its subsequent aggregation into toxic oligomers is one of the leading causes of Alzheimer's disease (AD). As a therapeutic approach, cyclic peptides have been...
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12
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Sanders HM, Jovcevski B, Marty MT, Pukala TL. Structural and mechanistic insights into amyloid-β and α-synuclein fibril formation and polyphenol inhibitor efficacy in phospholipid bilayers. FEBS J 2022; 289:215-230. [PMID: 34268903 PMCID: PMC8727495 DOI: 10.1111/febs.16122] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 06/11/2021] [Accepted: 07/15/2021] [Indexed: 01/03/2023]
Abstract
Under certain cellular conditions, functional proteins undergo misfolding, leading to a transition into oligomers which precede the formation of amyloid fibrils. Misfolding proteins are associated with neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. While the importance of lipid membranes in misfolding and disease aetiology is broadly accepted, the influence of lipid membranes during therapeutic design has been largely overlooked. This study utilized a biophysical approach to provide mechanistic insights into the effects of two lipid membrane systems (anionic and zwitterionic) on the inhibition of amyloid-β 40 and α-synuclein amyloid formation at the monomer, oligomer and fibril level. Large unilamellar vesicles (LUVs) were shown to increase fibrillization and largely decrease the effectiveness of two well-known polyphenol fibril inhibitors, (-)-epigallocatechin gallate (EGCG) and resveratrol; however, use of immunoblotting and ion mobility mass spectrometry revealed this occurs through varying mechanisms. Oligomeric populations in particular were differentially affected by LUVs in the presence of resveratrol, an elongation phase inhibitor, compared to EGCG, a nucleation targeted inhibitor. Ion mobility mass spectrometry showed EGCG interacts with or induces more compact forms of monomeric protein typical of off-pathway structures; however, binding is reduced in the presence of LUVs, likely due to partitioning in the membrane environment. Competing effects of the lipids and inhibitor, along with reduced inhibitor binding in the presence of LUVs, provide a mechanistic understanding of decreased inhibitor efficacy in a lipid environment. Together, this study highlights that amyloid inhibitor design may be misguided if effects of lipid membrane composition and architecture are not considered during development.
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Affiliation(s)
- Henry M. Sanders
- Department of Chemistry, School of Physical Sciences, The University of Adelaide, Adelaide, SA 5005, Australia,Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Blagojce Jovcevski
- Department of Chemistry, School of Physical Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Michael T. Marty
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Tara L. Pukala
- Department of Chemistry, School of Physical Sciences, The University of Adelaide, Adelaide, SA 5005, Australia,Correspondence: Tara L. Pukala: School of Physical Sciences, The University of Adelaide, Adelaide, SA 5005, Australia; ; Tel. +61 8 8313 5497
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13
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Schwarze B, Korn A, Höfling C, Zeitschel U, Krueger M, Roßner S, Huster D. Peptide backbone modifications of amyloid β (1-40) impact fibrillation behavior and neuronal toxicity. Sci Rep 2021; 11:23767. [PMID: 34887476 PMCID: PMC8660793 DOI: 10.1038/s41598-021-03091-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 11/25/2021] [Indexed: 11/23/2022] Open
Abstract
Fibril formation of amyloid β (Aβ) peptides is one of the key molecular events connected to Alzheimer's disease. The pathway of formation and mechanism of action of Aβ aggregates in biological systems is still object of very active research. To this end, systematic modifications of the Phe19-Leu34 hydrophobic contact, which has been reported in almost all structural studies of Aβ40 fibrils, helps understanding Aβ folding pathways and the underlying free energy landscape of the amyloid formation process. In our approach, a series of Aβ40 peptide variants with two types of backbone modifications, namely incorporation of (i) a methylene or an ethylene spacer group and (ii) a N-methylation at the amide functional group, of the amino acids at positions 19 or 34 was applied. These mutations are expected to challenge the inter-β-strand side chain contacts as well as intermolecular backbone β-sheet hydrogen bridges. Using a multitude of biophysical methods, it is shown that these backbone modifications lead, in most of the cases, to alterations in the fibril formation kinetics, a higher local structural heterogeneity, and a somewhat modified fibril morphology without generally impairing the fibril formation capacity of the peptides. The toxicological profile found for the variants depend on the type and extent of the modification.
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Affiliation(s)
- Benedikt Schwarze
- Institute for Medical Physics and Biophysics, Leipzig University, Härtelstr. 16/18, 04107, Leipzig, Germany
| | - Alexander Korn
- Institute for Medical Physics and Biophysics, Leipzig University, Härtelstr. 16/18, 04107, Leipzig, Germany
| | - Corinna Höfling
- Paul Flechsig Institute for Brain Research, Leipzig University, Liebigstr. 19, 04103, Leipzig, Germany
| | - Ulrike Zeitschel
- Paul Flechsig Institute for Brain Research, Leipzig University, Liebigstr. 19, 04103, Leipzig, Germany
| | - Martin Krueger
- Institute of Anatomy, Leipzig University, Liebigstr. 13, 04103, Leipzig, Germany
| | - Steffen Roßner
- Paul Flechsig Institute for Brain Research, Leipzig University, Liebigstr. 19, 04103, Leipzig, Germany
| | - Daniel Huster
- Institute for Medical Physics and Biophysics, Leipzig University, Härtelstr. 16/18, 04107, Leipzig, Germany.
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14
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Strazdaite S, Roeters SJ, Sakalauskas A, Sneideris T, Kirschner J, Pedersen KB, Schiøtt B, Jensen F, Weidner T, Smirnovas V, Niaura G. Interaction of Amyloid-β-(1-42) Peptide and Its Aggregates with Lipid/Water Interfaces Probed by Vibrational Sum-Frequency Generation Spectroscopy. J Phys Chem B 2021; 125:11208-11218. [PMID: 34597059 DOI: 10.1021/acs.jpcb.1c04882] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this study, we use surface-sensitive vibrational sum-frequency generation (VSFG) spectroscopy to investigate the interaction between model lipid monolayers and Aβ(1-42) in its monomeric and aggregated states. Combining VSFG with atomic force microscopy (AFM) and thioflavin T (ThT) fluorescence measurements, we found that only small aggregates with probably a β-hairpin-like structure adsorbed to the zwitterionic lipid monolayer (DOPC). In contrast, larger aggregates with an extended β-sheet structure adsorbed to a negatively charged lipid monolayer (DOPG). The adsorption of small, initially formed aggregates strongly destabilized both monolayers, but only the DOPC monolayer was completely disrupted. We showed that the intensity of the amide-II' band in achiral (SSP) and chiral (SPP) polarization combinations increased in time when Aβ(1-42) aggregates accumulated at the DOPG monolayer. Nevertheless, almost no adsorption of preformed mature fibrils to DOPG monolayers was detected. By performing spectral VSFG calculations, we revealed a clear correlation between the amide-II' signal and the degree of amyloid aggregates (e.g., oligomers or (proto)fibrils) of various Aβ(1-42) structures. The calculations showed that only structures with a significant amyloid β-sheet content have a strong amide-II' intensity, in line with previous Raman studies. The combination of the presented results substantiates the amide-II(') band as a legitimate amyloid marker.
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Affiliation(s)
- S Strazdaite
- Department of Organic Chemistry, Center for Physical Sciences and Technology, Sauletekio Ave. 3, Vilnius LT-10257, Lithuania
| | - S J Roeters
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - A Sakalauskas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio 7, LT-10257 Vilnius, Lithuania
| | - T Sneideris
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio 7, LT-10257 Vilnius, Lithuania
| | - J Kirschner
- Institute of Solid State Physics, TU Wien, Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria
| | - K B Pedersen
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - B Schiøtt
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - F Jensen
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - T Weidner
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - V Smirnovas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio 7, LT-10257 Vilnius, Lithuania
| | - G Niaura
- Department of Organic Chemistry, Center for Physical Sciences and Technology, Sauletekio Ave. 3, Vilnius LT-10257, Lithuania
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15
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Tian Y, Liang R, Kumar A, Szwedziak P, Viles JH. 3D-visualization of amyloid-β oligomer interactions with lipid membranes by cryo-electron tomography. Chem Sci 2021; 12:6896-6907. [PMID: 34123318 PMCID: PMC8153238 DOI: 10.1039/d0sc06426b] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Amyloid-β (Aβ) assemblies have been shown to bind to lipid bilayers. This can disrupt membrane integrity and cause a loss of cellular homeostasis, that triggers a cascade of events leading to Alzheimer's disease. However, molecular mechanisms of Aβ cytotoxicity and how the different assembly forms interact with the membrane remain enigmatic. Here we use cryo-electron tomography (cryoET) to obtain three-dimensional nano-scale images of various Aβ assembly types and their interaction with liposomes. Aβ oligomers and curvilinear protofibrils bind extensively to the lipid vesicles, inserting and carpeting the upper-leaflet of the bilayer. Aβ oligomers concentrate at the interface of vesicles and form a network of Aβ-linked liposomes, while crucially, monomeric and fibrillar Aβ have relatively little impact on the membrane. Changes to lipid membrane composition highlight a significant role for GM1-ganglioside in promoting Aβ-membrane interactions. The different effects of Aβ assembly forms observed align with the highlighted cytotoxicity reported for Aβ oligomers. The wide-scale incorporation of Aβ oligomers and curvilinear protofibrils into the lipid bilayer suggests a mechanism by which membrane integrity is lost. Cryo-electron tomography 3D imaging of amyloid-β oligomers carpeting the surface of lipid bilayers in near native conditions.![]()
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Affiliation(s)
- Yao Tian
- School of Biological and Chemical Sciences, Queen Mary University of London Mile End Road London E1 4NS UK
| | - Ruina Liang
- School of Biological and Chemical Sciences, Queen Mary University of London Mile End Road London E1 4NS UK
| | - Amit Kumar
- School of Biological and Chemical Sciences, Queen Mary University of London Mile End Road London E1 4NS UK
| | - Piotr Szwedziak
- Laboratory of Structural Cell Biology, Centre of New Technologies, University of Warsaw 02-097 Warsaw Poland .,ReMedy-International Research Agenda Unit, Centre of New Technologies, University of Warsaw 02-097 Warsaw Poland
| | - John H Viles
- School of Biological and Chemical Sciences, Queen Mary University of London Mile End Road London E1 4NS UK
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16
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Duan Y, Chen J, Jin Y, Tu Q, Wang S, Xiang J. Antibody-Free Determinations of Low-Mass, Soluble Oligomers of Aβ 42 and Aβ 40 by Planar Bilayer Lipid Membrane-Based Electrochemical Biosensor. Anal Chem 2021; 93:3611-3617. [PMID: 33571410 DOI: 10.1021/acs.analchem.0c05281] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disease among the elderly. Abnormal aggregates of both β-amyloid peptide (Aβ) subtypes, Aβ42 and Aβ40, are the typical neuropathology hallmarks of AD. However, because of the lack of specific recognition elements such as an antibody and aptamer, it is difficult to differentiate and determine the oligomers of Aβ42 and Aβ40 in clinic. In this paper, we developed a planar bilayer lipid membrane (BLM)-based electrochemical biosensor. According to the dynamic differences on oligomer-induced BLM damage, both low-mass, soluble oligomers of Aβ42 and Aβ40 (L-Aβ42O and L-Aβ40O) were measured in turn by electrochemical impedance spectroscopy. The BLM was supported by a porous 11-mercaptoundecanoic acid layer on a gold electrode, which amplified the impedance signal corresponding to the membrane damage and improved the detection sensitivity. The weakly charged surface of the BLM ensured the low non-specific adsorption of coexisting proteins in cerebrospinal fluid (CSF). Using the electrochemical biosensor, L-Aβ42O was determined within 20 min, with a linear range from 5 to 500 pM and a detection limit of 3 pM. Meanwhile, L-Aβ40O was determined within 60 min, with a linear range from 60 pM to 6.0 nM and a detection limit of 26 pM. The recoveries in oligomer-spiked artificial CSF and human CSF samples confirmed the accuracy and applicability of this proposed method in clinic. This work provides an antibody-free, highly selective, and sensitive method for simultaneous detections of L-Aβ42O and L-Aβ40O in real CSF samples, which is significant for the early diagnosis and prognosis of AD.
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Affiliation(s)
- Yuemei Duan
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China
| | - Jia Chen
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China
| | - Yan Jin
- Operation Center, The Third Xiangya Hospital, Central South University, Changsha 410013, China
| | - Qiuyun Tu
- Department of Geriatrics, The Fifth Affiliated Hospital of Sun Yat-Sen University, Zhuhai 519000, China
| | - Shuhui Wang
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China
| | - Juan Xiang
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China
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17
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Paul A, Viswanathan GK, Huber A, Arad E, Engel H, Jelinek R, Gazit E, Segal D. Inhibition of tau amyloid formation and disruption of its preformed fibrils by Naphthoquinone-Dopamine hybrid. FEBS J 2021; 288:4267-4290. [PMID: 33523571 DOI: 10.1111/febs.15741] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/02/2021] [Accepted: 01/28/2021] [Indexed: 01/10/2023]
Abstract
Misfolding and aggregation of tau protein, into pathological amyloids, are hallmarks of a group of neurodegenerative diseases collectively termed tauopathies and their modulation may be therapeutically valuable. Herein, we describe the synthesis and characterization of a dopamine-based hybrid molecule, naphthoquinone-dopamine (NQDA). Using thioflavin S assay, CD, transmission electron microscopy, dynamic light scattering, Congo Red birefringence, and large unilamellar vesicle leakage assays, we demonstrated its efficacy in inhibiting the in vitro aggregation of key tau-derived amyloidogenic fragments, PHF6 (VQIVYK) and PHF6* (VQIINK), prime drivers of aggregation of full-length tau in disease pathology. Isothermal titration calorimetry analysis revealed that the interaction between NQDA and PHF6 is spontaneous and has significant binding efficiency driven by both entropic and enthalpic processes. Furthermore, NQDA efficiently disassembled preformed fibrils of PHF6 and PHF6* into nontoxic species. Molecular dynamic simulations supported the in vitro results and provided a plausible mode of binding of NQDA with PHF6 fibril. NQDA was also capable of inhibiting the aggregation of full-length tau protein and disrupting its preformed fibrils in vitro in a dose-dependent manner. In a comparative study, the IC50 value (50% inhibition of fibril formation) of NQDA in inhibiting the aggregation of PHF6 (25 µm) was ~ 17 µm, which is lower than for other bona fide amyloid inhibitors, naphthoquinone-tryptophan, rosmarinic acid, epigallocatechin gallate, ~ 21, ~ 77, or ~ 19 µm, respectively. Comparable superiority of NQDA was observed for inhibition of PHF6*. These findings suggest that NQDA can be a useful scaffold for designing new therapeutics for Alzheimer's disease and other tauopathies.
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Affiliation(s)
- Ashim Paul
- Department of Molecular Microbiology and Biotechnology, Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Israel
| | - Guru KrishnaKumar Viswanathan
- Department of Molecular Microbiology and Biotechnology, Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Israel
| | - Adi Huber
- Department of Molecular Microbiology and Biotechnology, Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Israel
| | - Elad Arad
- Ilse Katz Institute for Nanoscale Science and Technology & Department of Chemistry, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Hamutal Engel
- Blavatnik Center for Drug Discovery, Tel Aviv University, Israel
| | - Raz Jelinek
- Ilse Katz Institute for Nanoscale Science and Technology & Department of Chemistry, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Ehud Gazit
- Department of Molecular Microbiology and Biotechnology, Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Israel.,Department of Materials Science and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Israel
| | - Daniel Segal
- Department of Molecular Microbiology and Biotechnology, Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Israel.,Sagol Interdisciplinary School of Neuroscience, Tel Aviv University, Israel
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18
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Kalita S, Kalita S, Paul A, Shah M, Kumar S, Mandal B. Site-specific single point mutation by anthranilic acid in hIAPP 8-37 enhances anti-amyloidogenic activity. RSC Chem Biol 2021; 2:266-273. [PMID: 34458787 PMCID: PMC8341151 DOI: 10.1039/d0cb00178c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 12/24/2020] [Indexed: 12/01/2022] Open
Abstract
Amylin or hIAPP, together with insulin, plays a significant role in glucose metabolism. However, it undergoes β-sheet rich amyloid formation associated with pancreatic β-cell dysfunction leading to type-2 diabetes (T2D). Recent studies suggest that restricting β-sheet formation in it may halt amyloid formation, which may limit the risk for the disease. Several peptide-based inhibitors have been reported to prevent aggregation. However, most of them have limitations, including low binding efficiency, active only at higher doses, poor solubility, and proteolytic degradation. Insertion of non-coded amino acids renders proteolytically stable peptides. We incorporated a structurally rigid β-amino acid, Anthranilic acid (Ant), at different sites within the central hydrophobic region of hIAPP and developed two singly mutated hIAPP8–37 peptidomimetics. These peptidomimetics inhibited the amyloid formation of hIAPP substantially even at low concentration, as evident from in vitro ThT, CD, FT-IR, TEM, and Congo red staining birefringence results. These peptidomimetics also disrupted the preformed aggregates formed by hIAPP into non-toxic species. These β-amino acid-based peptidomimetics can be an attractive scaffold for therapeutic design towards T2D or other protein misfolding diseases. β-Amino acid based peptidomimetics are attractive scaffolds for therapeutics design towards T2D. They prevent amyloid formation of hIAPP by forming non-fibrillar non-toxic aggregates.![]()
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Affiliation(s)
- Sourav Kalita
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati Assam-781039 India
| | - Sujan Kalita
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati Assam-781039 India
| | - Ashim Paul
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati Assam-781039 India
| | - Manisha Shah
- Department of Biosciences & Bioengineering, Indian Institute of Technology Guwahati Assam-781039 India
| | - Sachin Kumar
- Department of Biosciences & Bioengineering, Indian Institute of Technology Guwahati Assam-781039 India
| | - Bhubaneswar Mandal
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati Assam-781039 India
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19
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Paul A, Kumar S, Kalita S, Kalita S, Sarkar D, Bhunia A, Bandyopadhyay A, Mondal AC, Mandal B. An explicitly designed paratope of amyloid-β prevents neuronal apoptosis in vitro and hippocampal damage in rat brain. Chem Sci 2020; 12:2853-2862. [PMID: 34164050 PMCID: PMC8179358 DOI: 10.1039/d0sc04379f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Synthetic antibodies hold great promise in combating diseases, diagnosis, and a wide range of biomedical applications. However, designing a therapeutically amenable, synthetic antibody that can arrest the aggregation of amyloid-β (Aβ) remains challenging. Here, we report a flexible, hairpin-like synthetic paratope (SP1, ∼2 kDa), which prevents the aggregation of Aβ monomers and reverses the preformed amyloid fibril to a non-toxic species. Structural and biophysical studies further allowed dissecting the mode and affinity of molecular recognition events between SP1 and Aβ. Subsequently, SP1 reduces Aβ-induced neurotoxicity, neuronal apoptosis, and ROS-mediated oxidative damage in human neuroblastoma cells (SH-SY5Y). The non-toxic nature of SP1 and its ability to ameliorate hippocampal neurodegeneration in a rat model of AD demonstrate its therapeutic potential. This paratope engineering module could readily implement discoveries of cost-effective molecular probes to nurture the basic principles of protein misfolding, thus combating related diseases.
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Affiliation(s)
- Ashim Paul
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati (IITG) North Guwahati Assam-781039 India
| | - Sourav Kumar
- Neuroscience Research Unit, Department of Physiology, Raja Peary Mohan College Hooghly Uttarpara West Bengal-712258 India
| | - Sujan Kalita
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati (IITG) North Guwahati Assam-781039 India
| | - Sourav Kalita
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati (IITG) North Guwahati Assam-781039 India
| | - Dibakar Sarkar
- Biomolecular NMR and Drug Design Laboratory, Department of Biophysics, Bose Institute P-1/12 CIT Scheme VII (M) Kolkata 700054 India
| | - Anirban Bhunia
- Biomolecular NMR and Drug Design Laboratory, Department of Biophysics, Bose Institute P-1/12 CIT Scheme VII (M) Kolkata 700054 India
| | - Anupam Bandyopadhyay
- Peptide Engineering Laboratory, Department of Chemistry, Indian Institute of Technology Ropar Punjab-140001 India
| | - Amal Chandra Mondal
- Neuroscience Research Unit, Department of Physiology, Raja Peary Mohan College Hooghly Uttarpara West Bengal-712258 India .,Laboratory of Cellular & Molecular Neurobiology, School of Life Sciences, Jawaharlal Nehru University New Delhi-110 067 India
| | - Bhubaneswar Mandal
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati (IITG) North Guwahati Assam-781039 India
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20
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Dong X, Tang Y, Zhan C, Wei G. Green tea extract EGCG plays a dual role in Aβ 42 protofibril disruption and membrane protection: A molecular dynamic study. Chem Phys Lipids 2020; 234:105024. [PMID: 33278382 DOI: 10.1016/j.chemphyslip.2020.105024] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/13/2020] [Accepted: 11/29/2020] [Indexed: 11/18/2022]
Abstract
Amyloid plaques accumulated by the amyloid-β (Aβ) fibrillar aggregates are the major pathological hallmark of the Alzheimer's disease (AD). Inhibiting aggregation and disassembling preformed fibrils of Aβ by natural small molecules have developed into a promising therapeutic strategy for AD. Previous experiments reported that the green tea extract epigallocatechin-3-gallate (EGCG) can disrupt Aβ fibril and reduce Aβ cytotoxicity. The inhibitory ability of EGCG can also be affected by cellular membranes. Thus, it is essential to consider the membrane influences in the investigation of protofibril-disruptive capability of EGCG. Here, we performed multiple all-atom molecular dynamic simulations to investigate the effect of EGCG on the Aβ42 protofibril in the presence of a mixed POPC/POPG (7:3) lipid bilayer and the underlying molecular mechanisms of action. Our simulations show that in the presence of membrane bilayers, EGCG has a preference to bind to the membrane, and this binding alters the binding modes between Aβ42 protofibril and the lipid bilayer, leading to a reduced membrane thinning, indicative of a protective effect of EGCG on the membrane. And EGCG still displays a disruptive effect on Aβ42 protofibril, albeit with a lesser extent of disruption than that in the membrane-free environment. EGCG destabilizes the two hydrophobic core regions (L17-F19-I31 and F4-L34-V36), and disrupts the intrachain K28-A42 salt bridges. Our results reveal that in the presence of lipid bilayers, EGCG plays a dual role in Aβ42 protofibril disruption and membrane protection, suggesting that EGCG could be a potential effective drug candidate for the treatment of AD.
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Affiliation(s)
- Xuewei Dong
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai, 200438, People's Republic of China.
| | - Yiming Tang
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai, 200438, People's Republic of China
| | - Chendi Zhan
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai, 200438, People's Republic of China
| | - Guanghong Wei
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai, 200438, People's Republic of China.
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21
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Marshall KE, Vadukul DM, Staras K, Serpell LC. Misfolded amyloid-β-42 impairs the endosomal-lysosomal pathway. Cell Mol Life Sci 2020; 77:5031-5043. [PMID: 32025743 PMCID: PMC7658065 DOI: 10.1007/s00018-020-03464-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 01/13/2020] [Accepted: 01/14/2020] [Indexed: 12/29/2022]
Abstract
Misfolding and aggregation of proteins is strongly linked to several neurodegenerative diseases, but how such species bring about their cytotoxic actions remains poorly understood. Here we used specifically-designed optical reporter probes and live fluorescence imaging in primary hippocampal neurons to characterise the mechanism by which prefibrillar, oligomeric forms of the Alzheimer's-associated peptide, Aβ42, exert their detrimental effects. We used a pH-sensitive reporter, Aβ42-CypHer, to track Aβ internalisation in real-time, demonstrating that oligomers are rapidly taken up into cells in a dynamin-dependent manner, and trafficked via the endo-lysosomal pathway resulting in accumulation in lysosomes. In contrast, a non-assembling variant of Aβ42 (vAβ42) assayed in the same way is not internalised. Tracking ovalbumin uptake into cells using CypHer or Alexa Fluor tags shows that preincubation with Aβ42 disrupts protein uptake. Our results identify a potential mechanism by which amyloidogenic aggregates impair cellular function through disruption of the endosomal-lysosomal pathway.
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Affiliation(s)
- Karen E Marshall
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, BN1 9QG, UK
| | - Devkee M Vadukul
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, BN1 9QG, UK
| | - Kevin Staras
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, BN1 9QG, UK.
| | - Louise C Serpell
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, BN1 9QG, UK.
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22
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Pani I, Madhu P, Najiya N, Aayush A, Mukhopadhyay S, Pal SK. Differentiating Conformationally Distinct Alzheimer's Amyloid-β Oligomers Using Liquid Crystals. J Phys Chem Lett 2020; 11:9012-9018. [PMID: 33040538 DOI: 10.1021/acs.jpclett.0c01867] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Soluble oligomers of amyloidogenic proteins like an amyloid-β (Aβ) peptide are believed to exhibit toxic effects in neurodegenerative diseases. The structural classification of oligomers indicates two fundamentally distinct oligomers, namely, fibrillar and prefibrillar oligomers that are recognized by OC and A11 conformation-specific antibodies, respectively. Previous studies have indicated that the interaction of Aβ oligomers with the lipid membrane is one of the mechanisms by which these oligomers exert their toxic effects in Alzheimer's disease. Here, we report that the orientational ordering of liquid crystals (LC) can be used to study the membrane-induced aggregation of Aβ oligomers at nanomolar concentrations. Our results demonstrate a faster fibrillation kinetics of OC-positive fibrillar Aβ oligomers with the lipid monolayer in comparison to that of the A11-positive prefibrillar Aβ oligomers. Our findings suggest a general strategy for distinguishing conformationally distinct soluble oligomers that are formed by a number of amyloidogenic proteins on lipid-decorated aqueous-LC interfaces.
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23
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Paul A, Huber A, Rand D, Gosselet F, Cooper I, Gazit E, Segal D. Naphthoquinone–Dopamine Hybrids Inhibit α‐Synuclein Aggregation, Disrupt Preformed Fibrils, and Attenuate Aggregate‐Induced Toxicity. Chemistry 2020; 26:16486-16496. [DOI: 10.1002/chem.202003374] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Indexed: 12/17/2022]
Affiliation(s)
- Ashim Paul
- Department of Molecular Microbiology and Biotechnology School of Molecular Cell Biology and Biotechnology Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
| | - Adi Huber
- Department of Molecular Microbiology and Biotechnology School of Molecular Cell Biology and Biotechnology Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
| | - Daniel Rand
- The Joseph Sagol Neuroscience Center Sheba Medical Center, Tel Hashomer Ramat Gan 52621 Israel
| | - Fabien Gosselet
- UR 2465 Blood-brain barrier Laboratory (LBHE) Artois University 62300 Lens France
| | - Itzik Cooper
- The Joseph Sagol Neuroscience Center Sheba Medical Center, Tel Hashomer Ramat Gan 52621 Israel
| | - Ehud Gazit
- Department of Molecular Microbiology and Biotechnology School of Molecular Cell Biology and Biotechnology Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
- Department of Materials Science and Engineering Iby and Aladar Fleischman Faculty of Engineering Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
| | - Daniel Segal
- Department of Molecular Microbiology and Biotechnology School of Molecular Cell Biology and Biotechnology Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
- Sagol Interdisciplinary School of Neuroscience Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel
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24
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Roy R, Pradhan K, Khan J, Das G, Mukherjee N, Das D, Ghosh S. Human Serum Albumin-Inspired Glycopeptide-Based Multifunctional Inhibitor of Amyloid-β Toxicity. ACS OMEGA 2020; 5:18628-18641. [PMID: 32775865 PMCID: PMC7407538 DOI: 10.1021/acsomega.0c01028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 05/19/2020] [Indexed: 05/07/2023]
Abstract
In Alzheimer's disease (AD), insoluble Aβ42 peptide fragments self-aggregate and form oligomers and fibrils in the brain, causing neurotoxicity. Further, the presence of redox-active metal ions such as Cu2+ enhances the aggregation process through chelation with these Aβ42 aggregates as well as generation of Aβ42-mediated reactive oxygen species (ROS). Herein, we have adopted a bioinspired strategy to design and develop a multifunctional glycopeptide hybrid molecule (Glupep), which can serve as a potential AD therapeutic. This molecule consists of a natural metal-chelating tetrapeptide motif of human serum albumin (HSA), a β-sheet breaker peptide, and a sugar moiety for better bioavailability. We performed different biophysical and docking experiments, which revealed that Glupep not only associates with Aβ42 but also prevents its self-aggregation to form toxic oligomers and fibrils. Moreover, Glupep was also shown to sequester out Cu2+ from the Aβ-Cu2+ complex, reducing the ROS formation and toxicity. Besides, this study also revealed that Glupep could protect PC12-derived neurons from Aβ-Cu2+-mediated toxicity by reducing intracellular ROS generation and stabilizing the mitochondrial membrane potential. All these exciting features show Glupep to be a potent inhibitor of Aβ42-mediated multifaceted toxicity and a prospective therapeutic lead for AD.
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Affiliation(s)
- Rajsekhar Roy
- Department
of Bioscience & Bioengineering, Indian
Institute of Technology Jodhpur, NH 65, Surpura Bypass Road, Karwar, Rajasthan 342037, India
| | - Krishnangsu Pradhan
- Organic
and Medicinal Chemistry and Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical
Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, WB, India
| | - Juhee Khan
- Organic
and Medicinal Chemistry and Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical
Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, WB, India
| | - Gaurav Das
- Organic
and Medicinal Chemistry and Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical
Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, WB, India
| | - Nabanita Mukherjee
- Department
of Bioscience & Bioengineering, Indian
Institute of Technology Jodhpur, NH 65, Surpura Bypass Road, Karwar, Rajasthan 342037, India
| | - Durba Das
- Department
of Bioscience & Bioengineering, Indian
Institute of Technology Jodhpur, NH 65, Surpura Bypass Road, Karwar, Rajasthan 342037, India
| | - Surajit Ghosh
- Organic
and Medicinal Chemistry and Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical
Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, WB, India
- Department
of Bioscience & Bioengineering, Indian
Institute of Technology Jodhpur, NH 65, Surpura Bypass Road, Karwar, Rajasthan 342037, India
- Academy
of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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25
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Fibrillization of 40-Residue β-Amyloid Peptides in Membrane-Like Environments Leads to Different Fibril Structures and Reduced Molecular Polymorphisms. Biomolecules 2020; 10:biom10060881. [PMID: 32521743 PMCID: PMC7356566 DOI: 10.3390/biom10060881] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 05/28/2020] [Accepted: 06/04/2020] [Indexed: 12/31/2022] Open
Abstract
The molecular-level polymorphism in β-Amyloid (Aβ) fibrils have recently been considered as a pathologically relevant factor in Alzheimer’s disease (AD). Studies showed that the structural deviations in human-brain-seeded Aβ fibrils potentially correlated with the clinical histories of AD patients. For the 40-residue Aβ (Aβ40) fibrils derived from human brain tissues, a predominant molecular structure was proposed based on solid-state nuclear magnetic resonance (ssNMR) spectroscopy. However, previous studies have shown that the molecular structures of Aβ40 fibrils were sensitive to their growth conditions in aqueous environments. We show in this work that biological membranes and their phospholipid bilayer mimics serve as environmental factors to reduce the structural heterogeneity in Aβ40 fibrils. Fibrillization in the presence of membranes leads to fibril structures that are significantly different to the Aβ40 fibrils grown in aqueous solutions. Fibrils grown from multiple types of membranes, including the biological membranes extracted from the rats’ synaptosomes, shared similar ssNMR spectral features. Our studies emphasize the biological relevance of membranes in Aβ40 fibril structures and fibrillization processes.
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26
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Ghosh P, Rana P, Rangachari V, Saha J, Steen E, Vaidya A. A game-theoretic approach to deciphering the dynamics of amyloid- β aggregation along competing pathways. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191814. [PMID: 32431878 PMCID: PMC7211858 DOI: 10.1098/rsos.191814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 04/01/2020] [Indexed: 06/11/2023]
Abstract
Aggregation of amyloid-β (Aβ) peptides is a significant event that underpins Alzheimer's disease (AD). Aβ aggregates, especially the low-molecular weight oligomers, are the primary toxic agents in AD pathogenesis. Therefore, there is increasing interest in understanding their formation and behaviour. In this paper, we use our previously established results on heterotypic interactions between Aβ and fatty acids (FAs) to investigate off-pathway aggregation under the control of FA concentrations to develop a mathematical framework that captures the mechanism. Our framework to define and simulate the competing on- and off-pathways of Aβ aggregation is based on the principles of game theory. Together with detailed simulations and biophysical experiments, our models describe the dynamics involved in the mechanisms of Aβ aggregation in the presence of FAs to adopt multiple pathways. Specifically, our reduced-order computations indicate that the emergence of off- or on-pathway aggregates are tightly controlled by a narrow set of rate constants, and one could alter such parameters to populate a particular oligomeric species. These models agree with the detailed simulations and experimental data on using FA as a heterotypic partner to modulate the temporal parameters. Predicting spatio-temporal landscape along competing pathways for a given heterotypic partner such as lipids is a first step towards simulating scenarios in which the generation of specific 'conformer strains' of Aβ could be predicted. This approach could be significant in deciphering the mechanisms of amyloid aggregation and strain generation, which are ubiquitously observed in many neurodegenerative diseases.
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Affiliation(s)
- Preetam Ghosh
- Department of Computer Science, Virginia Commonwealth University, Richmond, VA 23220, USA
| | - Pratip Rana
- Department of Computer Science, Virginia Commonwealth University, Richmond, VA 23220, USA
| | - Vijayaraghavan Rangachari
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA
| | - Jhinuk Saha
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA
| | - Edward Steen
- Department of Mathematical Science, Montclair State University, Montclair, NJ 07043, USA
| | - Ashwin Vaidya
- Department of Mathematical Science, Montclair State University, Montclair, NJ 07043, USA
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27
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Kalita S, Kalita S, Paul A, Sarkar A, Mandal B. Peptidomimetics prepared by tail-to-side chain one component peptide stapling inhibit Alzheimer's amyloid-β fibrillogenesis. Chem Sci 2020; 11:4171-4179. [PMID: 34122880 PMCID: PMC8152599 DOI: 10.1039/c9sc06076f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Alzheimer's disease (AD) is the most common form of dementia affecting the elderly population worldwide. Despite enormous efforts and considerable advancement in research, no therapeutic agents have come to light to date. However, many peptide-based and small molecule inhibitors interact efficiently with the amyloid-β (Aβ) peptide and alter its aggregation pathway. On the other hand, stapled peptides have been developed mainly to stabilize α-helix conformations and study protein–protein interactions. β-Sheet stabilization or destabilization by stapled peptides has not been explored enough. Herein, we describe the generation of a library of “tail-to-side chain” stapled peptides via lactamization and their application for the first time as modulators of Aβ1-40 self-association and fibrillogenesis. They also disrupt the preformed fibrillar aggregates into nontoxic species. Their stability in the presence of proteolytic enzymes is increased due to stapling. Therefore, the stapled peptides thus formed can be useful as potent amyloid aggregation inhibitors and pave a therapeutic pathway for combating amyloid-related diseases. Also, they may help in gaining insight into the process of aggregation. Tail to side-chain stapled peptides inhibit fibrillogenesis of Alzheimer's amyloid β peptide by facilitating off-pathway aggregation.![]()
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Affiliation(s)
- Sujan Kalita
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati Assam-781039 India
| | - Sourav Kalita
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati Assam-781039 India
| | - Ashim Paul
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati Assam-781039 India
| | - Amar Sarkar
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati Assam-781039 India
| | - Bhubaneswar Mandal
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati Assam-781039 India
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28
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Vander Zanden CM, Wampler L, Bowers I, Watkins EB, Majewski J, Chi EY. Fibrillar and Nonfibrillar Amyloid Beta Structures Drive Two Modes of Membrane-Mediated Toxicity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16024-16036. [PMID: 31509701 PMCID: PMC7385729 DOI: 10.1021/acs.langmuir.9b02484] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In Alzheimer's disease, the amyloid-beta peptide (Aβ) is implicated in neuronal toxicity via interactions with the cell membrane. Monomeric Aβ (Aβm) is intrinsically disordered, but it can adopt a range of aggregated conformations with varying toxicities from short fibrillar oligomers (FO), to globular nonfibrillar oligomers (NFO), and full-length amyloid fibrils. NFO is considered to be the most toxic, followed by fibrils, and finally Aβm. To elucidate molecular-level membrane interactions that contribute to their different toxicities, we used liquid surface X-ray scattering and Langmuir trough insertion assays to compare Aβm, FO, and NFO surface activities and interactions with anionic DMPG lipid monolayers at the air/water interface. All Aβ species were highly surface active and rapidly adopted β-sheet rich structures upon adsorption to the air/water interface. Likewise, all Aβ species had affinity for the anionic membrane. Aβm rapidly converted to β-sheet rich assemblies upon binding the membrane, and these aggregated structures of Aβm and FO disrupted hexagonally packed lipid domains and resulted in membrane thinning and instability. In contrast, NFO perturbed membrane structure by extracting lipids from the air/water interface and causing macroscale membrane deformations. Altogether, our results support two models for membrane-mediated Aβ toxicity: fibril-induced reorganization of lipid packing and NFO-induced membrane destabilization and lipid extraction. This work provides a structural understanding of Aβ neurotoxicity via membrane interactions and aids the effort in understanding early events in Alzheimer's disease and other neurodegenerative diseases.
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Affiliation(s)
- Crystal M Vander Zanden
- Center for Biomedical Engineering , University of New Mexico , Albuquerque , New Mexico 87131 , United States
- Department of Chemical and Biological Engineering , University of New Mexico , Albuquerque , New Mexico 87131 , United States
- Department of Chemistry and Biochemistry , University of Colorado Colorado Springs , Colorado Springs , Colorado 80918 , United States
| | - Lois Wampler
- Department of Biomedical Engineering , Texas A&M University , College Station , Texas 77843 , United States
| | - Isabella Bowers
- Department of Engineering and Technology , Southeast Missouri State University , Cape Girardeau , Missouri 63701 , United States
| | - Erik B Watkins
- MPA-11: Materials Synthesis and Integrated Devices , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Jaroslaw Majewski
- Department of Chemical and Biological Engineering , University of New Mexico , Albuquerque , New Mexico 87131 , United States
- Division of Molecular and Cellular Biosciences , National Science Foundation , Alexandria , Virginia 22314 , United States
- Theoretical Biology and Biophysics , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Eva Y Chi
- Center for Biomedical Engineering , University of New Mexico , Albuquerque , New Mexico 87131 , United States
- Department of Chemical and Biological Engineering , University of New Mexico , Albuquerque , New Mexico 87131 , United States
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29
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Long K, Williams TL, Urbanc B. Insulin Inhibits Aβ42 Aggregation and Prevents Aβ42-Induced Membrane Disruption. Biochemistry 2019; 58:4519-4529. [DOI: 10.1021/acs.biochem.9b00696] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kaho Long
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | | | - Brigita Urbanc
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
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30
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Viswanathan GK, Paul A, Gazit E, Segal D. Naphthoquinone Tryptophan Hybrids: A Promising Small Molecule Scaffold for Mitigating Aggregation of Amyloidogenic Proteins and Peptides. Front Cell Dev Biol 2019; 7:242. [PMID: 31750300 PMCID: PMC6843079 DOI: 10.3389/fcell.2019.00242] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 10/02/2019] [Indexed: 12/22/2022] Open
Abstract
A current challenge faced by researchers is the lack of disease-modifying therapeutics for amyloid formation that is associated with several human diseases. Although the monomeric proteins or peptides involved in various amyloidogenic diseases do not have amino acid sequence homology, there appears to be a structural correlation among the amyloid assemblies, which are responsible for distinct pathological conditions. Here, we review our work on Naphthoquinone Tryptophan (NQTrp) hybrids, a small molecule scaffold that can generically modulate neuronal and non-neuronal amyloid aggregation both in vitro and in vivo. NQTrp reduces the net amyloid load by inhibiting the process of amyloid formation and disassembling the pre-formed fibrils, both in a dose-dependent manner. As a plausible mechanism of action, NQTrp effectively forms hydrogen bonding and hydrophobic interactions, such as π-π stacking, with the vital residues responsible for the initial nucleation of protein/peptide aggregation. This review highlights the effectiveness of the NQTrp hybrid scaffold for developing novel small molecule modulators of amyloid aggregation.
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Affiliation(s)
- Guru KrishnaKumar Viswanathan
- Department of Molecular Microbiology and Biotechnology, School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Ashim Paul
- Department of Molecular Microbiology and Biotechnology, School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Ehud Gazit
- Department of Molecular Microbiology and Biotechnology, School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Daniel Segal
- Department of Molecular Microbiology and Biotechnology, School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv, Israel.,Interdisciplinary Sagol School of Neurosciences, Tel Aviv University, Tel Aviv, Israel
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31
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Paul A, Viswanathan GK, Mahapatra S, Balboni G, Pacifico S, Gazit E, Segal D. Antagonistic Activity of Naphthoquinone-Based Hybrids toward Amyloids Associated with Alzheimer's Disease and Type-2 Diabetes. ACS Chem Neurosci 2019; 10:3510-3520. [PMID: 31282646 DOI: 10.1021/acschemneuro.9b00123] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Protein misfolding and amyloid formation are associated with various human diseases including Alzheimer's disease (AD), Parkinson's disease (PD), and Type-2 Diabetes mellitus (T2DM). No disease-modifying therapeutics are available for them. Despite the lack of sequence homology between the corresponding proteins, aromatic residues are recognized as common key motifs in the formation and stabilization of amyloid structures via π-π stacking. Thus, targeting aromatic recognition interfaces could be a useful approach for inhibiting amyloid formation as well as disrupting the preformed amyloid fibrils. Combining experimental and computational approaches, we demonstrated the anti-amyloidogenic effect of naphthoquinone-tryptophan-based hybrid molecules toward PHF6 (τ-derived aggregative peptide), Amyloid β (Aβ42), and human islet amyloid polypeptide (hIAPP) implicated in AD and T2DM, respectively. These hybrid molecules significantly inhibited the aggregation and disrupted their preformed fibrillar aggregates in vitro, in a dose-dependent manner as evident from Thioflavin T/S binding assay, CD spectroscopy, and electron microscopy. Dye leakage assay from LUVs and cell-based experiments indicated that the hybrid molecules inhibit membrane disruption and cytotoxicity induced by these amyloids. Furthermore, in silico studies provided probable mechanistic insights into the interaction of these molecules with the amyloidogenic proteins in their monomeric or aggregated forms, including the role of hydrophobic interaction, hydrogen bond formation, and packing during inhibition of aggregation and fibril disassembly. Our findings may help in designing novel therapeutics toward AD, T2DM, and other proteinopathies based on the naphthoquinone derived hybrid molecules.
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Affiliation(s)
| | | | | | - Gianfranco Balboni
- Department of Life and Environmental Sciences - Unit of Pharmaceutical, Pharmacological and Nutraceutical Sciences, University of Cagliari, via Ospedale 72, I-09124 Cagliari, Italy
| | - Salvatore Pacifico
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara, via Fossato di Mortara 17-19, I-44121 Ferrara, Italy
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32
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Ewald M, Henry S, Lambert E, Feuillie C, Bobo C, Cullin C, Lecomte S, Molinari M. High speed atomic force microscopy to investigate the interactions between toxic Aβ 1-42 peptides and model membranes in real time: impact of the membrane composition. NANOSCALE 2019; 11:7229-7238. [PMID: 30924478 DOI: 10.1039/c8nr08714h] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Due to an aging population, neurodegenerative diseases have become a major health issue, the most common being Alzheimer's disease. The mechanisms leading to neuronal loss still remain unclear but recent studies suggest that soluble Aβ oligomers have deleterious effects on neuronal membranes. Here, high-speed atomic force microscopy was used to assess the effect of oligomeric species of a variant of Aβ1-42 amyloid peptide on model membranes with various lipid compositions. Results showed that the peptide does not interact with membranes composed of phosphatidylcholine and sphingomyelin. Ganglioside GM1, but not cholesterol, is required for the peptide to interact with the membrane. Interestingly, when they are both present, a fast disruption of the membrane was observed. It suggests that the presence of ganglioside GM1 and cholesterol in membranes promotes the interaction of the oligomeric Aβ1-42 peptide with the membrane. This interaction leads to the membrane's destruction in a few seconds. This study highlights the power of high-speed atomic force microscopy to explore lipid-protein interactions with high spatio-temporal resolution.
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Affiliation(s)
- M Ewald
- LRN EA 4682, Université de Reims Champagne-Ardenne, F-51685 Reims, France.
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33
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Paul A, Zhang BD, Mohapatra S, Li G, Li YM, Gazit E, Segal D. Novel Mannitol-Based Small Molecules for Inhibiting Aggregation of α-Synuclein Amyloids in Parkinson's Disease. Front Mol Biosci 2019; 6:16. [PMID: 30968030 PMCID: PMC6438916 DOI: 10.3389/fmolb.2019.00016] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 03/01/2019] [Indexed: 11/16/2022] Open
Abstract
The aggregation of the amyloidogenic protein α-synuclein (α-Syn) into toxic oligomers and mature fibrils is the major pathological hallmark of Parkinson's disease (PD). Small molecules that inhibit α-Syn aggregation thus may be useful therapeutics for PD. Mannitol and naphthoquinone-tryptophan (NQTrp) have been shown in the past to inhibit α-Syn aggregation by different mechanisms. Herein, we tested whether the conjugation of Mannitol and NQTrp may result in enhance efficacy toward α-Syn. The molecules were conjugated either by a click linker or via a PEG linker. The effect of the conjugate molecules on α-Syn aggregation in vitro was monitored using Thioflavin T fluorescence assay, circular dichroism, transmission electron microscopy, and Congo red birefringence assay. One of the conjugate molecules was found to be more effective than the two parent molecules and as effective as a mixture of the two. The conjugate molecules attenuated the disruptive effect of α-Syn on artificial membrane of Large Unilamellar Vesicles as monitored by dye leakage assay. The conjugates were found to be have low cytotoxicity and reduced toxicity of α-Syn toward SH-SY5Y neuroblastoma cells. These novel designed entities can be attractive scaffold for the development of therapeutic agents for PD.
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Affiliation(s)
- Ashim Paul
- School of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Bo-Dou Zhang
- Department of Chemistry, Tsinghua University, Beijing, China
| | - Satabdee Mohapatra
- School of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Gao Li
- Department of Chemistry, Tsinghua University, Beijing, China
| | - Yan-Mei Li
- Department of Chemistry, Tsinghua University, Beijing, China.,Institute of Parkinson Disease, Beijing Institute for Brain Disorders, Beijing, China.,Center for Synthetic and Systems Biology, Tsinghua University, Beijing, China
| | - Ehud Gazit
- School of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Daniel Segal
- School of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel.,Sagol Interdisciplinary School of Neurosciences, Tel Aviv University, Tel Aviv, Israel
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34
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Zhao G, Dong X, Sun Y. Self-Assembled Curcumin-Poly(carboxybetaine methacrylate) Conjugates: Potent Nano-Inhibitors against Amyloid β-Protein Fibrillogenesis and Cytotoxicity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:1846-1857. [PMID: 30134656 DOI: 10.1021/acs.langmuir.8b01921] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Fibrillogenesis of amyloid β-protein (Aβ) is a pathological hallmark of Alzheimer's disease, so inhibition of Aβ aggregation is considered as an important strategy for the precaution and treatment of AD. Curcumin (Cur) has been recognized as an effective inhibitor of Aβ fibrillogenesis, but its potential application is limited by its poor bioavailability. Herein, we proposed to conjugate Cur to a zwitterionic polymer, poly(carboxybetaine methacrylate) (pCB), and synthesized three Cur@pCB conjugates of different degrees of substitution (DS, 1.9-2.9). Cur@pCB conjugates self-assembled into nanogels of 120-190 nm. The inhibition effects of Cur@pCB conjugates on the fibrillation and cytotoxicity of Aβ42 was investigated by extensive biophysical and biological analyses. Thioflavin T fluorescence assays and atomic force microscopic observations revealed that the Cur@pCB conjugates were much more efficient than molecular curcumin on inhibiting Aβ42 fibrillation, and cytotoxicity assays also indicated the same tendency. Of the three conjugates, Cur1@pCB of the lowest DS (1.97) exhibited the best performance; 5 μM Cur1@pCB functioned similarly with 25 μM free curcumin. Moreover, 5 μM Cur1@pCB increased the cell viability by 43% but free curcumin at the same concentration showed little effect. It is considered that the highly hydrated state of the zwitterionic polymers resulted in the superiority of Cur@pCB over free curcumin. Namely, the dense hydration layer on the conjugates strongly stabilized the bound Aβ on curcumin anchored on the polymer, suppressing the conformational transition of the protein to β-sheet-rich structures. This was demonstrated by circular dichroism spectroscopy, in which Cur1@pCB was proven to be the strongest in the three conjugates. The research has thus revealed a new function of zwitterionic polymer pCBMA and provided new insights into the development of more potent nanoinhibitors for suppressing Aβ fibrillogenesis and cytotoxicity.
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Affiliation(s)
- Guangfu Zhao
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology , Tianjin University , Tianjin 300072 , China
| | - Xiaoyan Dong
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology , Tianjin University , Tianjin 300072 , China
| | - Yan Sun
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology , Tianjin University , Tianjin 300072 , China
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35
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Paul A, Li WH, Viswanathan GK, Arad E, Mohapatra S, Li G, Jelinek R, Gazit E, Li YM, Segal D. Tryptophan–glucosamine conjugates modulate tau-derived PHF6 aggregation at low concentrations. Chem Commun (Camb) 2019; 55:14621-14624. [DOI: 10.1039/c9cc06868f] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Tryptophan–glucosamine conjugates efficiently inhibit tau-derived PHF6-peptide fibrillization and disrupt its preformed fibrils at very low concentrations.
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Affiliation(s)
- Ashim Paul
- School of Molecular Cell Biology & Biotechnology
- Tel Aviv University
- Israel
| | - Wen-Hao Li
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- China
| | | | - Elad Arad
- Department of Chemistry
- Ben Gurion University of the Negev
- Beer Sheva 84105
- Israel
| | - Satabdee Mohapatra
- School of Molecular Cell Biology & Biotechnology
- Tel Aviv University
- Israel
| | - Gao Li
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- China
| | - Raz Jelinek
- Department of Chemistry
- Ben Gurion University of the Negev
- Beer Sheva 84105
- Israel
| | - Ehud Gazit
- School of Molecular Cell Biology & Biotechnology
- Tel Aviv University
- Israel
| | - Yan-Mei Li
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- China
- Beijing Institute for Brain Disorders
| | - Daniel Segal
- School of Molecular Cell Biology & Biotechnology
- Tel Aviv University
- Israel
- Sagol Interdisciplinary School of Neurosciences
- Tel Aviv University
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36
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Tatulian SA, Kandel N. Membrane Pore Formation by Peptides Studied by Fluorescence Techniques. Methods Mol Biol 2019; 2003:449-464. [PMID: 31218629 DOI: 10.1007/978-1-4939-9512-7_19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Pore formation in cellular membranes by pathogen-derived proteins is a mechanism utilized by a set of microbes to exert their cytotoxic effect. On the other hand, the host cells have developed a defense mechanism to produce antimicrobial peptides to kill the pathogens by a similar, membrane perforation mechanism. Furthermore, certain endogenous proteins or peptides kill the parent cells through membrane permeabilization. Analysis of the molecular details of membrane pore formation is often conducted using artificial systems, such as bilayer lipid membranes and synthetic peptides. This chapter describes two fluorescence-based methods to study peptide-induced membrane leakage. One method involves preparation of lipid vesicles loaded with a fluorophore (e.g., calcein or carboxyfluorescein) at a self-quenching concentration. If the externally added peptide forms relatively large pores (≥1 nm in diameter), the fluorophore leaks out and undergoes dequenching, resulting in time-dependent increase in fluorescence. The other method is designed to monitor smaller pores (<1 nm in diameter). It involves preparation of vesicles in a Ca2+-less buffer, containing a Ca2+-dependent fluorophore, such as Quin-2. Removal of external Quin-2 by a desalting column and addition of an appropriate concentration of CaCl2 externally sequesters Quin-2 and Ca2+ ions by the vesicle membrane. Addition of the pore-forming peptide to these vesicles results in membrane permeabilization, Ca2+ influx and binding to Quin-2. In both cases, the kinetics of the increase of fluorescence and its equilibrium levels allow quantitative analysis of the pore formation mechanism.
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Affiliation(s)
- Suren A Tatulian
- Department of Physics, University of Central Florida, Orlando, FL, USA.
| | - Nabin Kandel
- Department of Physics, University of Central Florida, Orlando, FL, USA
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37
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Inhibitory Effect of Naphthoquinone-Tryptophan Hybrid towards Aggregation of PAP f39 Semen Amyloid. Molecules 2018; 23:molecules23123279. [PMID: 30544943 PMCID: PMC6320874 DOI: 10.3390/molecules23123279] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 12/03/2018] [Accepted: 12/07/2018] [Indexed: 01/02/2023] Open
Abstract
PAP248–286, a 39 amino acid peptide fragment, derived from the prostatic acid phosphatase secreted in human semen, forms amyloid fibrils and facilitates the attachment of retroviruses to host cells that results in the enhancement of viral infection. Therefore, the inhibition of amyloid formation by PAP248–286 (termed PAP f39) may likely reduce HIV transmission in AIDS. In this study, we show that the naphthoquinone tryptophan (NQTrp) hybrid molecule significantly inhibited PAP f39 aggregation in vitro in a dose-dependent manner as observed from the ThT assay, ANS assay, and transmission electron microscopy imaging. We found that even at a sub-molar concentration of 20:1 [PAP f39:NQTrp], NQTrp could reduce >50% amyloid formation. NQTrp inhibition of PAP f39 aggregation resulted in non-toxic intermediate species as determined by the vesicle leakage assay. Isothermal titration calorimetry and molecular docking revealed that the binding of NQTrp and PAP f39 is spontaneous, and NQTrp predominantly interacts with the polar and charged residues of the peptide by forming hydrogen bonds and hydrophobic contacts with a strong binding energy. Collectively, these findings indicate that NQTrp holds significant potential as a small molecule inhibitor of semen amyloids.
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38
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Mechanistic insights into remodeled Tau-derived PHF6 peptide fibrils by Naphthoquinone-Tryptophan hybrids. Sci Rep 2018; 8:71. [PMID: 29311706 PMCID: PMC5758761 DOI: 10.1038/s41598-017-18443-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 12/12/2017] [Indexed: 11/20/2022] Open
Abstract
Intra-cellular tau protein tangles and extra-cellular β-amyloid plaques are hallmarks of Alzheimer’s disease (AD), characterized by the conversion of natively unfolded monomeric protein/peptide into misfolded β-sheet rich aggregates. Therefore, inhibiting the aggregation cascade or disassembling the pre-formed aggregates becomes a pivotal event in disease treatment. In the present study, we show that Naphthoquinone-Tryptophan hybrids, i.e., NQTrp and Cl-NQTrp significantly disrupted the pre-formed fibrillar aggregates of Tau-derived PHF6 (VQIVYK) peptide and full-length tau protein in vitro, in a dose-dependent manner as evident from ThS assay, CD spectroscopy, and TEM. Molecular dynamics simulation of PHF6 oligomers and fibrils with the Naphthoquinone-Tryptophan hybrids provides a possible structure-function based mechanism-of-action, highlighting the role of hydrophobic interaction and hydrogen bond formation during fibril disassembly. These findings signify the effectiveness of NQTrp and Cl-NQTrp in disassembling fibrillar aggregates and may help in designing novel hybrid molecules for AD treatment.
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39
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Bryksa BC, Yada RY. Protein Structure Insights into the Bilayer Interactions of the Saposin-Like Domain of Solanum tuberosum Aspartic Protease. Sci Rep 2017; 7:16911. [PMID: 29208977 PMCID: PMC5717070 DOI: 10.1038/s41598-017-16734-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 11/16/2017] [Indexed: 12/26/2022] Open
Abstract
Many plant aspartic proteases contain a saposin-like domain whose principal functions are intracellular sorting and host defence. Its structure is characterised by helical segments cross-linked by three highly conserved cystines. The present study on the saposin-like domain of Solanum tuberosum aspartic protease revealed that acidification from inactive to active conditions causes dimerisation and a strand-to-helix secondary structure transition independent of bilayer interaction. Bilayer fusion was shown to occur under reducing conditions yielding a faster shift to larger vesicle sizes relative to native conditions, implying that a lower level structural motif might be bilayer-active. Characterisation of peptide sequences based on the domain’s secondary structural regions showed helix-3 to be active (~4% of the full domain’s activity), and mutation of its sole positively charged residue resulted in loss of activity and disordering of structure. Also, the peptides’ respective circular dichroism spectra suggested that native folding within the full domain is dependent on surrounding structure. Overall, the present study reveals that the aspartic protease saposin-like domain active structure is an open saposin fold dimer whose formation is pH-dependent, and that a bilayer-active motif shared among non-saposin membrane-active proteins including certain plant defence proteins is nested within an overall structure essential for native functionality.
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Affiliation(s)
- Brian C Bryksa
- Ontario Agricultural College, University of Guelph, N1G 2W1, Guelph, Ontario, Canada
| | - Rickey Y Yada
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, V6T 1Z4, British Columbia, Canada.
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40
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Rana P, Dean DN, Steen ED, Vaidya A, Rangachari V, Ghosh P. Fatty Acid Concentration and Phase Transitions Modulate Aβ Aggregation Pathways. Sci Rep 2017; 7:10370. [PMID: 28871093 PMCID: PMC5583381 DOI: 10.1038/s41598-017-09794-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 07/31/2017] [Indexed: 01/04/2023] Open
Abstract
Aggregation of amyloid β (Aβ) peptides is a significant event that underpins Alzheimer disease (AD) pathology. Aβ aggregates, especially the low-molecular weight oligomers, are the primary toxic agents in AD and hence, there is increasing interest in understanding their formation and behavior. Aggregation is a nucleation-dependent process in which the pre-nucleation events are dominated by Aβ homotypic interactions. Dynamic flux and stochasticity during pre-nucleation renders the reactions susceptible to perturbations by other molecules. In this context, we investigate the heterotypic interactions between Aβ and fatty acids (FAs) by two independent tool-sets such as reduced order modelling (ROM) and ensemble kinetic simulation (EKS). We observe that FAs influence Aβ dynamics distinctively in three broadly-defined FA concentration regimes containing non-micellar, pseudo-micellar or micellar phases. While the non-micellar phase promotes on-pathway fibrils, pseudo-micellar and micellar phases promote predominantly off-pathway oligomers, albeit via subtly different mechanisms. Importantly off-pathway oligomers saturate within a limited molecular size, and likely with a different overall conformation than those formed along the on-pathway, suggesting the generation of distinct conformeric strains of Aβ, which may have profound phenotypic outcomes. Our results validate previous experimental observations and provide insights into potential influence of biological interfaces in modulating Aβ aggregation pathways.
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Affiliation(s)
- Pratip Rana
- Department of Computer Science, Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Dexter N Dean
- Department of Chemistry & Biochemistry, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Edward D Steen
- Department of Mathematical Science, Montclair State University, Montclair, NJ, 07043, USA
| | - Ashwin Vaidya
- Department of Mathematical Science, Montclair State University, Montclair, NJ, 07043, USA
| | - Vijayaraghavan Rangachari
- Department of Chemistry & Biochemistry, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Preetam Ghosh
- Department of Computer Science, Virginia Commonwealth University, Richmond, VA, 23284, USA.
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41
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Paul A, Kumar S, Kalita S, Ghosh AK, Mondal AC, Mandal B. A Peptide Based Pro-drug Disrupts Alzheimer’s Amyloid into Non-toxic Species and Reduces Aβ Induced Toxicity In Vitro. Int J Pept Res Ther 2017. [DOI: 10.1007/s10989-017-9602-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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42
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Ford L, Crossley M, Vadukul DM, Kemenes G, Serpell LC. Structure-dependent effects of amyloid-β on long-term memory in Lymnaea stagnalis. FEBS Lett 2017; 591:1236-1246. [PMID: 28337747 PMCID: PMC5435943 DOI: 10.1002/1873-3468.12633] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 02/24/2017] [Accepted: 03/20/2017] [Indexed: 12/03/2022]
Abstract
Amyloid‐β (Aβ) peptides are implicated in the causation of memory loss, neuronal impairment, and neurodegeneration in Alzheimer's disease. Our recent work revealed that Aβ 1–42 and Aβ 25–35 inhibit long‐term memory (LTM) recall in Lymnaea stagnalis (pond snail) in the absence of cell death. Here, we report the characterization of the active species prepared under different conditions, describe which Aβ species is present in brain tissue during the behavioral recall time point and relate the sequence and structure of the oligomeric species to the resulting neuronal properties and effect on LTM. Our results suggest that oligomers are the key toxic Aβ1–42 structures, which likely affect LTM through synaptic plasticity pathways, and that Aβ 1–42 and Aβ 25–35 cannot be used as interchangeable peptides.
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Affiliation(s)
- Lenzie Ford
- Sussex NeuroscienceSchool of Life SciencesUniversity of SussexBrightonUK
- Present address: Department of NeuroscienceColumbia UniversityNew YorkNY10032USA
- Present address: Howard Hughes Medical InstituteColumbia UniversityNew YorkNY10032USA
| | - Michael Crossley
- Sussex NeuroscienceSchool of Life SciencesUniversity of SussexBrightonUK
| | - Devkee M. Vadukul
- Sussex NeuroscienceSchool of Life SciencesUniversity of SussexBrightonUK
| | - György Kemenes
- Sussex NeuroscienceSchool of Life SciencesUniversity of SussexBrightonUK
| | - Louise C. Serpell
- Sussex NeuroscienceSchool of Life SciencesUniversity of SussexBrightonUK
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43
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Goldblatt G, Cilenti L, Matos JO, Lee B, Ciaffone N, Wang QX, Tetard L, Teter K, Tatulian SA. Unmodified and pyroglutamylated amyloid β peptides form hypertoxic hetero-oligomers of unique secondary structure. FEBS J 2017; 284:1355-1369. [PMID: 28294556 DOI: 10.1111/febs.14058] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 03/07/2017] [Accepted: 03/08/2017] [Indexed: 11/29/2022]
Abstract
Amyloid β (Aβ) peptide plays a major role in Alzheimer's disease (AD) and occurs in multiple forms, including pyroglutamylated Aβ (AβpE). Identification and characterization of the most cytotoxic Aβ species is necessary for advancement in AD diagnostics and therapeutics. While in brain tissue multiple Aβ species act in combination, structure/toxicity studies and immunotherapy trials have been focused on individual forms of Aβ. As a result, the molecular composition and the structural features of "toxic Aβ oligomers" have remained unresolved. Here, we have used a novel approach, hydration from gas phase coupled with isotope-edited Fourier transform infrared (FTIR) spectroscopy, to identify the prefibrillar assemblies formed by Aβ and AβpE and to resolve the structures of both peptides in combination. The peptides form unusual β-sheet oligomers stabilized by intramolecular H-bonding as opposed to intermolecular H-bonding in the fibrils. Time-dependent morphological changes in peptide assemblies have been visualized by atomic force microscopy. Aβ/AβpE hetero-oligomers exert unsurpassed cytotoxic effect on PC12 cells as compared to oligomers of individual peptides or fibrils. These findings lead to a novel concept that Aβ/AβpE hetero-oligomers, not just Aβ or AβpE oligomers, constitute the main neurotoxic conformation. The hetero-oligomers thus present a new biomarker that may be targeted for development of more efficient diagnostic and immunotherapeutic strategies to combat AD.
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Affiliation(s)
- Greg Goldblatt
- Biomedical Sciences Graduate Program, University of Central Florida, Orlando, FL, USA
| | - Lucia Cilenti
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Jason O Matos
- Biotechnology Graduate Program, University of Central Florida, Orlando, FL, USA
| | - Briana Lee
- Nanotechnology Graduate Program, NanoScience Technology Center, University of Central Florida, Orlando, FL, USA
| | - Nicholas Ciaffone
- Nanotechnology Graduate Program, NanoScience Technology Center, University of Central Florida, Orlando, FL, USA
| | - Qing X Wang
- Physics Graduate Program, College of Sciences, University of Central Florida, Orlando, FL, USA
| | - Laurene Tetard
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Department of Physics, College of Sciences, University of Central Florida, Orlando, FL, USA
| | - Ken Teter
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Suren A Tatulian
- Department of Physics, College of Sciences, University of Central Florida, Orlando, FL, USA
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44
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Urbanc B. Flexible N‐Termini of Amyloid β‐Protein Oligomers: A Link between Structure and Activity? Isr J Chem 2017. [DOI: 10.1002/ijch.201600097] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Brigita Urbanc
- Department of Physics Drexel University Philadelphia, PA 19104 USA
- Faculty of Mathematics and Physics Jadranska ulica 19 1000 Ljubljana Slovenia
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45
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Disaggregation of Amylin Aggregate by Novel Conformationally Restricted Aminobenzoic Acid containing α/β and α/γ Hybrid Peptidomimetics. Sci Rep 2017; 7:40095. [PMID: 28054630 PMCID: PMC5214534 DOI: 10.1038/srep40095] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 12/01/2016] [Indexed: 11/24/2022] Open
Abstract
Diabetes has emerged as a threat to the current world. More than ninety five per cent of all the diabetic population has type 2 diabetes mellitus (T2DM). Aggregates of Amylin hormone, which is co-secreted with insulin from the pancreatic β-cells, inhibit the activities of insulin and glucagon and cause T2DM. Importance of the conformationally restricted peptides for drug design against T2DM has been invigorated by recent FDA approval of Symlin, which is a large conformationally restricted peptide. However, Symlin still has some issues including solubility, oral bioavailability and cost of preparation. Herein, we introduced a novel strategy for conformationally restricted peptide design adopting a minimalistic approach for cost reduction. We have demonstrated efficient inhibition of amyloid formation of Amylin and its disruption by a novel class of conformationally restricted β-sheet breaker hybrid peptidomimetics (BSBHps). We have inserted β, γ and δ -aminobenzoic acid separately into an amyloidogenic peptide sequence, synthesized α/β, α/γ and α/δ hybrid peptidomimetics, respectively. Interestingly, we observed the aggregation inhibitory efficacy of α/β and α/γ BSBHps, but not of α/δ analogues. They also disrupt existing amyloids into non-toxic forms. Results may be useful for newer drug design against T2DM as well as other amyloidoses and understanding amyloidogenesis.
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46
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Lynn SA, Keeling E, Munday R, Gabha G, Griffiths H, Lotery AJ, Ratnayaka JA. The complexities underlying age-related macular degeneration: could amyloid beta play an important role? Neural Regen Res 2017; 12:538-548. [PMID: 28553324 PMCID: PMC5436342 DOI: 10.4103/1673-5374.205083] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Age-related macular degeneration (AMD) causes irreversible loss of central vision for which there is no effective treatment. Incipient pathology is thought to occur in the retina for many years before AMD manifests from midlife onwards to affect a large proportion of the elderly. Although genetic as well as non-genetic/environmental risks are recognized, its complex aetiology makes it difficult to identify susceptibility, or indeed what type of AMD develops or how quickly it progresses in different individuals. Here we summarize the literature describing how the Alzheimer's-linked amyloid beta (Aβ) group of misfolding proteins accumulate in the retina. The discovery of this key driver of Alzheimer's disease in the senescent retina was unexpected and surprising, enabling an altogether different perspective of AMD. We argue that Aβ fundamentally differs from other substances which accumulate in the ageing retina, and discuss our latest findings from a mouse model in which physiological amounts of Aβ were subretinally-injected to recapitulate salient features of early AMD within a short period. Our discoveries as well as those of others suggest the pattern of Aβ accumulation and pathology in donor aged/AMD tissues are closely reproduced in mice, including late-stage AMD phenotypes, which makes them highly attractive to study dynamic aspects of Aβ-mediated retinopathy. Furthermore, we discuss our findings revealing how Aβ behaves at single-cell resolution, and consider the long-term implications for neuroretinal function. We propose Aβ as a key element in switching to a diseased retinal phenotype, which is now being used as a biomarker for late-stage AMD.
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Affiliation(s)
- Savannah A Lynn
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Eloise Keeling
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Rosie Munday
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Gagandeep Gabha
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Helen Griffiths
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Andrew J Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.,Eye Unit, University Southampton NHS Trust, Southampton, United Kingdom
| | - J Arjuna Ratnayaka
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
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47
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Kumar S, Paul A, Kalita S, Ghosh AK, Mandal B, Mondal AC. Protective effects of β-sheet breaker α/β-hybrid peptide against amyloid β-induced neuronal apoptosis in vitro. Chem Biol Drug Des 2016; 89:888-900. [PMID: 27995757 DOI: 10.1111/cbdd.12912] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 09/13/2016] [Accepted: 11/08/2016] [Indexed: 12/31/2022]
Abstract
Alzheimer's disease is most common neurodegenerative disorder and is characterized by increased production of soluble amyloid-β oligomers, the main toxic species predominantly formed from aggregation of monomeric amyloid-β (Aβ). Increased production of Aβ invokes a cascade of oxidative damages to neurons and eventually leads to neuronal death. This study was aimed to investigate the neuroprotective effects of a β-sheet breaker α/β-hybrid peptide (BSBHp) and the underlying mechanisms against Aβ40 -induced neurotoxicity in human neuroblastoma SH-SY5Y cells. Cells were pretreated with the peptide Aβ40 to induce neurotoxicity. Assays for cell viability, cell membrane damage, cellular apoptosis, generation of reactive oxygen species (ROS), intracellular free Ca2+ , and key apoptotic protein levels were performed in vitro. Our results showed that pretreatment with BSBHp significantly attenuates Aβ40 -induced toxicity by retaining cell viability, suppressing generation of ROS, Ca2+ levels, and effectively protects neuronal apoptosis by suppressing pro-apoptotic protein Bax and up-regulating antiapoptotic protein Bcl-2. These results suggest that α/β-hybrid peptide has neuroprotective effects against Aβ40 -induced oxidative stress, which might be a potential therapeutic agent for treating or preventing neurodegenerative diseases.
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Affiliation(s)
- Sourav Kumar
- Neuroscience Research Unit, Department of Physiology, Raja Peary Mohan College, Uttarpara, Hooghly, West Bengal, India
| | - Ashim Paul
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati (IITG), North Guwahati, Assam, India
| | - Sourav Kalita
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati (IITG), North Guwahati, Assam, India
| | - Anup Kumar Ghosh
- Department of Instrumentation Science, Jadavpur University, Kolkata, West Bengal, India
| | - Bhubaneswar Mandal
- Laboratory of Peptide and Amyloid Research, Department of Chemistry, Indian Institute of Technology Guwahati (IITG), North Guwahati, Assam, India
| | - Amal Chandra Mondal
- Neuroscience Research Unit, Department of Physiology, Raja Peary Mohan College, Uttarpara, Hooghly, West Bengal, India.,School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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48
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Thomaier M, Gremer L, Dammers C, Fabig J, Neudecker P, Willbold D. High-Affinity Binding of Monomeric but Not Oligomeric Amyloid-β to Ganglioside GM1 Containing Nanodiscs. Biochemistry 2016; 55:6662-6672. [DOI: 10.1021/acs.biochem.6b00829] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Maren Thomaier
- Institute
of Complex Systems (ICS-6), Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany
- Institut
für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Lothar Gremer
- Institute
of Complex Systems (ICS-6), Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany
- Institut
für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Christina Dammers
- Institute
of Complex Systems (ICS-6), Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Judith Fabig
- Institute
of Complex Systems (ICS-6), Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Philipp Neudecker
- Institute
of Complex Systems (ICS-6), Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany
- Institut
für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Dieter Willbold
- Institute
of Complex Systems (ICS-6), Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany
- Institut
für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
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49
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Taylor-Walker G, Lynn SA, Keeling E, Munday R, Johnston DA, Page A, Scott JA, Goverdhan S, Lotery AJ, Ratnayaka JA. The Alzheimer's-related amyloid beta peptide is internalised by R28 neuroretinal cells and disrupts the microtubule associated protein 2 (MAP-2). Exp Eye Res 2016; 153:110-121. [PMID: 27751744 PMCID: PMC5131630 DOI: 10.1016/j.exer.2016.10.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 09/12/2016] [Accepted: 10/11/2016] [Indexed: 11/15/2022]
Abstract
Age-related Macular Degeneration (AMD) is a common, irreversible blinding condition that leads to the loss of central vision. AMD has a complex aetiology with both genetic as well as environmental risks factors, and share many similarities with Alzheimer's disease. Recent findings have contributed significantly to unravelling its genetic architecture that is yet to be matched by molecular insights. Studies are made more challenging by observations that aged and AMD retinas accumulate the highly pathogenic Alzheimer's-related Amyloid beta (Aβ) group of peptides, for which there appears to be no clear genetic basis. Analyses of human donor and animal eyes have identified retinal Aβ aggregates in retinal ganglion cells (RGC), the inner nuclear layer, photoreceptors as well as the retinal pigment epithelium. Aβ is also a major drusen constituent; found correlated with elevated drusen-load and age, with a propensity to aggregate in retinas of advanced AMD. Despite this evidence, how such a potent driver of neurodegeneration might impair the neuroretina remains incompletely understood, and studies into this important aspect of retinopathy remains limited. In order to address this we exploited R28 rat retinal cells which due to its heterogeneous nature, offers diverse neuroretinal cell-types in which to study the molecular pathology of Aβ. R28 cells are also unaffected by problems associated with the commonly used RGC-5 immortalised cell-line, thus providing a well-established model in which to study dynamic Aβ effects at single-cell resolution. Our findings show that R28 cells express key neuronal markers calbindin, protein kinase C and the microtubule associated protein-2 (MAP-2) by confocal immunofluorescence which has not been shown before, but also calretinin which has not been reported previously. For the first time, we reveal that retinal neurons rapidly internalised Aβ1-42, the most cytotoxic and aggregate-prone amongst the Aβ family. Furthermore, exposure to physiological amounts of Aβ1-42 for 24 h correlated with impairment to neuronal MAP-2, a cytoskeletal protein which regulates microtubule dynamics in axons and dendrites. Disruption to MAP-2 was transient, and had recovered by 48 h, although internalised Aβ persisted as discrete puncta for as long as 72 h. To assess whether Aβ could realistically localise to living retinas to mediate such effects, we subretinally injected nanomolar levels of oligomeric Aβ1-42 into wildtype mice. Confocal microscopy revealed the presence of focal Aβ deposits in RGC, the inner nuclear and the outer plexiform layers 8 days later, recapitulating naturally-occurring patterns of Aβ aggregation in aged retinas. Our novel findings describe how retinal neurons internalise Aβ to transiently impair MAP-2 in a hitherto unreported manner. MAP-2 dysfunction is reported in AMD retinas, and is thought to be involved in remodelling and plasticity of post-mitotic neurons. Our insights suggest a molecular pathway by which this could occur in the senescent eye leading to complex diseases such as AMD. Molecular basis of complex retinopathies such as AMD is incompletely understood. The Alzheimer's-related Aβ peptides are rapidly internalised by retinal neurons. Internalised Aβ is retained within neurons and transiently impairs MAP-2. Subretinally injected Aβ mimics its naturally-occurring distribution in aged retinas.
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Affiliation(s)
- George Taylor-Walker
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, SGH, MP806, Tremona Road, Southampton, SO16 6YD, United Kingdom
| | - Savannah A Lynn
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, SGH, MP806, Tremona Road, Southampton, SO16 6YD, United Kingdom
| | - Eloise Keeling
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, SGH, MP806, Tremona Road, Southampton, SO16 6YD, United Kingdom
| | - Rosie Munday
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, SGH, MP806, Tremona Road, Southampton, SO16 6YD, United Kingdom
| | - David A Johnston
- Biomedical Imaging Unit, University of Southampton, SGH, MP12, Tremona Road, Southampton, SO16 6YD, United Kingdom
| | - Anton Page
- Biomedical Imaging Unit, University of Southampton, SGH, MP12, Tremona Road, Southampton, SO16 6YD, United Kingdom
| | - Jennifer A Scott
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, SGH, MP806, Tremona Road, Southampton, SO16 6YD, United Kingdom
| | - Srini Goverdhan
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, SGH, MP806, Tremona Road, Southampton, SO16 6YD, United Kingdom
| | - Andrew J Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, SGH, MP806, Tremona Road, Southampton, SO16 6YD, United Kingdom; Eye Unit, University Southampton NHS Trust, Southampton, SO16 6YD, United Kingdom
| | - J Arjuna Ratnayaka
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, SGH, MP806, Tremona Road, Southampton, SO16 6YD, United Kingdom.
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50
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Rajasekhar K, Madhu C, Govindaraju T. Natural Tripeptide-Based Inhibitor of Multifaceted Amyloid β Toxicity. ACS Chem Neurosci 2016; 7:1300-10. [PMID: 27355515 DOI: 10.1021/acschemneuro.6b00175] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Accumulation of amyloid beta (Aβ) peptide and its aggregates in the human brain is considered as one of the hallmarks of Alzheimer's disease (AD). The polymorphic oligomers and fully grown fibrillar aggregates of Aβ exhibit different levels of neuronal toxicity. Moreover, aggregation of Aβ in the presence of redox-active metal ions like Cu(2+) is responsible for the additional trait of cellular toxicity induced by the generation of reactive oxygen species (ROS). Herein, a multifunctional peptidomimetic inhibitor (P6) has been presented, based on a naturally occurring metal chelating tripeptide (GHK) and the inhibitor of Aβ aggregation. It was shown by employing various biophysical studies that P6 interact with Aβ and prevent the formation of toxic Aβ forms like oligomeric species and fibrillar aggregates. Further, P6 successfully sequestered Cu(2+) from the Aβ-Cu(2+) complex and maintained it in a redox-dormant state to prevent the generation of ROS. P6 inhibited membrane disruption by Aβ oligomers and efficiently prevented DNA damage caused by the Aβ-Cu(2+) complex. PC12 cells were rescued from multifaceted Aβ toxicity when treated with P6, and the amount of ROS generated in cells was reduced. These attributes make P6 a potential therapeutic candidate to ameliorate the multifaceted Aβ toxicity in AD.
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Affiliation(s)
- K. Rajasekhar
- Bioorganic Chemistry Laboratory,
New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur
P. O., Bengaluru 560064, Karnataka, India
| | - Chilakapati Madhu
- Bioorganic Chemistry Laboratory,
New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur
P. O., Bengaluru 560064, Karnataka, India
| | - T. Govindaraju
- Bioorganic Chemistry Laboratory,
New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur
P. O., Bengaluru 560064, Karnataka, India
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