1
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Hall LG, Czeczor JK, Connor T, Botella J, De Jong KA, Renton MC, Genders AJ, Venardos K, Martin SD, Bond ST, Aston-Mourney K, Howlett KF, Campbell JA, Collier GR, Walder KR, McKenzie M, Ziemann M, McGee SL. Amyloid beta 42 alters cardiac metabolism and impairs cardiac function in male mice with obesity. Nat Commun 2024; 15:258. [PMID: 38225272 PMCID: PMC10789867 DOI: 10.1038/s41467-023-44520-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 12/15/2023] [Indexed: 01/17/2024] Open
Abstract
There are epidemiological associations between obesity and type 2 diabetes, cardiovascular disease and Alzheimer's disease. The role of amyloid beta 42 (Aβ42) in these diverse chronic diseases is obscure. Here we show that adipose tissue releases Aβ42, which is increased from adipose tissue of male mice with obesity and is associated with higher plasma Aβ42. Increasing circulating Aβ42 levels in male mice without obesity has no effect on systemic glucose homeostasis but has obesity-like effects on the heart, including reduced cardiac glucose clearance and impaired cardiac function. The closely related Aβ40 isoform does not have these same effects on the heart. Administration of an Aβ-neutralising antibody prevents obesity-induced cardiac dysfunction and hypertrophy. Furthermore, Aβ-neutralising antibody administration in established obesity prevents further deterioration of cardiac function. Multi-contrast transcriptomic analyses reveal that Aβ42 impacts pathways of mitochondrial metabolism and exposure of cardiomyocytes to Aβ42 inhibits mitochondrial complex I. These data reveal a role for systemic Aβ42 in the development of cardiac disease in obesity and suggest that therapeutics designed for Alzheimer's disease could be effective in combating obesity-induced heart failure.
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Affiliation(s)
- Liam G Hall
- Institute for Mental and Physical Health and Clinical Translation, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
- Department of Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, Canada
| | - Juliane K Czeczor
- Institute for Mental and Physical Health and Clinical Translation, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
- Becton Dickinson GmbH, Medical Affairs, 69126, Heidelberg, Germany
| | - Timothy Connor
- Institute for Mental and Physical Health and Clinical Translation, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Javier Botella
- Institute for Mental and Physical Health and Clinical Translation, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Kirstie A De Jong
- Institute for Mental and Physical Health and Clinical Translation, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
- Institute of Experimental Cardiovascular Research, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany
| | - Mark C Renton
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Amanda J Genders
- Institute for Mental and Physical Health and Clinical Translation, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
- Department of Nutrition, Dietetics and Food, School of Clinical Sciences and Victorian Heart Institute, Monash University, Melbourne, Australia
| | - Kylie Venardos
- Institute for Mental and Physical Health and Clinical Translation, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Sheree D Martin
- Institute for Mental and Physical Health and Clinical Translation, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Simon T Bond
- Institute for Mental and Physical Health and Clinical Translation, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
- Baker Heart and Diabetes Institute, Melbourne, Australia
| | - Kathryn Aston-Mourney
- Institute for Mental and Physical Health and Clinical Translation, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Kirsten F Howlett
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | | | | | - Ken R Walder
- Institute for Mental and Physical Health and Clinical Translation, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Matthew McKenzie
- School of Life and Environmental Science, Deakin University, Geelong, Australia
| | - Mark Ziemann
- School of Life and Environmental Science, Deakin University, Geelong, Australia
| | - Sean L McGee
- Institute for Mental and Physical Health and Clinical Translation, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia.
- Ambetex Pty Ltd, Geelong, Australia.
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2
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Kinger S, Dubey AR, Kumar P, Jagtap YA, Choudhary A, Kumar A, Prajapati VK, Dhiman R, Mishra A. Molecular Chaperones' Potential against Defective Proteostasis of Amyotrophic Lateral Sclerosis. Cells 2023; 12:cells12091302. [PMID: 37174703 PMCID: PMC10177248 DOI: 10.3390/cells12091302] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 04/24/2023] [Accepted: 04/27/2023] [Indexed: 05/15/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neuronal degenerative condition identified via a build-up of mutant aberrantly folded proteins. The native folding of polypeptides is mediated by molecular chaperones, preventing their pathogenic aggregation. The mutant protein expression in ALS is linked with the entrapment and depletion of chaperone capacity. The lack of a thorough understanding of chaperones' involvement in ALS pathogenesis presents a significant challenge in its treatment. Here, we review how the accumulation of the ALS-linked mutant FUS, TDP-43, SOD1, and C9orf72 proteins damage cellular homeostasis mechanisms leading to neuronal loss. Further, we discuss how the HSP70 and DNAJ family co-chaperones can act as potential targets for reducing misfolded protein accumulation in ALS. Moreover, small HSPB1 and HSPB8 chaperones can facilitate neuroprotection and prevent stress-associated misfolded protein apoptosis. Designing therapeutic strategies by pharmacologically enhancing cellular chaperone capacity to reduce mutant protein proteotoxic effects on ALS pathomechanisms can be a considerable advancement. Chaperones, apart from directly interacting with misfolded proteins for protein quality control, can also filter their toxicity by initiating strong stress-response pathways, modulating transcriptional expression profiles, and promoting anti-apoptotic functions. Overall, these properties of chaperones make them an attractive target for gaining fundamental insights into misfolded protein disorders and designing more effective therapies against ALS.
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Affiliation(s)
- Sumit Kinger
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Jodhpur 342037, India
| | - Ankur Rakesh Dubey
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Jodhpur 342037, India
| | - Prashant Kumar
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Jodhpur 342037, India
| | - Yuvraj Anandrao Jagtap
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Jodhpur 342037, India
| | - Akash Choudhary
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Jodhpur 342037, India
| | - Amit Kumar
- Discipline of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore 453552, India
| | - Vijay Kumar Prajapati
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, Ajmer 305817, India
| | - Rohan Dhiman
- Laboratory of Mycobacterial Immunology, Department of Life Science, National Institute of Technology, Rourkela 769008, India
| | - Amit Mishra
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Jodhpur 342037, India
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3
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Chen EW, Guo Z. Preparation and Fractionation of Heterogeneous Aβ42 Oligomers with Different Aggregation Properties. Methods Mol Biol 2023; 2551:29-39. [PMID: 36310194 DOI: 10.1007/978-1-0716-2597-2_3] [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] [Indexed: 06/16/2023]
Abstract
Deposition of amyloid-β (Aβ) aggregates in the form of amyloid plaques is a central feature of Alzheimer's disease. The end products of Aβ aggregation are amyloid fibrils. Soluble Aβ aggregates called oligomers are also formed either on or off the pathway of fibril formation. The amyloid fibrils from different clinical subtypes of Alzheimer's disease have been found to adopt different structures, a phenomenon called fibril polymorphism. Meanwhile, different types of Aβ oligomers have also been found. Recently, it has been shown that different types of Aβ42 oligomers may form fibrils of different structures, linking oligomer heterogeneity to fibril polymorphism. In this chapter, we describe methods to prepare heterogeneous Aβ42 oligomers and to quantify the concentration of these oligomers at a low micromolar range using a fluorescamine method. Fractionation of these oligomers by size using ultrafiltration filters allows for the formation of Aβ42 fibrils with different structural properties.
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Affiliation(s)
- Erica W Chen
- Department of Neurology, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, CA, USA
| | - Zhefeng Guo
- Department of Neurology, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, CA, USA.
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4
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Panja S, Siegel D, Camandola S, de Cabo R, Ross D, Mallela K. FAD-deficient P187S mutation of NAD(P)H:quinone oxidoreductase 1 (NQO1*2) binds and accelerates β-amyloid aggregation. Biosci Rep 2022; 42:BSR20220643. [PMID: 36281795 PMCID: PMC9664297 DOI: 10.1042/bsr20220643] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 09/28/2022] [Accepted: 10/24/2022] [Indexed: 02/03/2024] Open
Abstract
Alzheimer's disease (AD) is one of the most prominent neurodegenerative diseases. Results from animal and cellular models suggest that FAD-deficient forms of NAD(P)H quinone oxidoreductase 1 (NQO1) may accelerate the aggregation of Alzheimer's amyloid-β peptide (Aβ1-42). Here, we examined in vitro whether NQO1 and its FAD-deficient P187S mutation (NQO1*2) directly interact with Aβ1-42 and modify its rate of aggregation. When monitored using the fluorescence of either noncovalent thioflavin T (ThT) or HiLyte Fluor 647 (HF647) dye covalently attached to the Aβ1-42 peptide, the aggregation kinetics of Aβ1-42 were markedly more rapid in the presence of NQO1*2 than the wild-type (WT) NQO1. Experiments using apo-NQO1 indicate that this increase is linked to the inability of NQO1*2 to bind to FAD. Furthermore, dicoumarol, an NQO1 inhibitor that binds near the FAD-binding site and stabilizes NQO1*2, markedly decreased the aggregation kinetics of Aβ1-42. Imaging flow cytometry confirmed in-vitro coaggregation of NQO1 isoforms and Aβ1-42. Aβ1-42 alone forms rod-shaped fibril structures while in the presence of NQO1 isoforms, Aβ1-42 is incorporated in the middle of larger globular protein aggregates surrounded by NQO1 molecules. Isothermal titration calorimetry (ITC) analysis indicates that Aβ1-42 interacts with NQO1 isoforms with a specific stoichiometry through a hydrophobic interaction with positive enthalpy and entropy changes. These data define the kinetics, mechanism, and shape of coaggregates of Aβ1-42 and NQO1 isoforms and the potential relevance of FAD-deficient forms of NQO1 for amyloid aggregation diseases.
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Affiliation(s)
- Sudipta Panja
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, 12850 East Montview Boulevard, MS C238-V20, Aurora, CO 80045, U.S.A
| | - David Siegel
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, 12850 East Montview Boulevard, MS C238-V20, Aurora, CO 80045, U.S.A
| | - Simonetta Camandola
- Experimental Gerontology Section, National Institute of Aging, National Institutes of Health, Baltimore MD, U.S.A
| | - Rafael de Cabo
- Experimental Gerontology Section, National Institute of Aging, National Institutes of Health, Baltimore MD, U.S.A
| | - David Ross
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, 12850 East Montview Boulevard, MS C238-V20, Aurora, CO 80045, U.S.A
| | - Krishna M.G. Mallela
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, 12850 East Montview Boulevard, MS C238-V20, Aurora, CO 80045, U.S.A
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5
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Matuszyk MM, Garwood CJ, Ferraiuolo L, Simpson JE, Staniforth RA, Wharton SB. Biological and methodological complexities of beta-amyloid peptide: Implications for Alzheimer's disease research. J Neurochem 2021; 160:434-453. [PMID: 34767256 DOI: 10.1111/jnc.15538] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 10/29/2021] [Accepted: 11/09/2021] [Indexed: 01/01/2023]
Abstract
Although controversial, the amyloid cascade hypothesis remains central to the Alzheimer's disease (AD) field and posits amyloid-beta (Aβ) as the central factor initiating disease onset. In recent years, there has been an increase in emphasis on studying the role of low molecular weight aggregates, such as oligomers, which are suggested to be more neurotoxic than fibrillary Aβ. Other Aβ isoforms, such as truncated Aβ, have also been implicated in disease. However, developing a clear understanding of AD pathogenesis has been hampered by the complexity of Aβ biochemistry in vitro and in vivo. This review explores factors contributing to the lack of consistency in experimental approaches taken to model Aβ aggregation and toxicity and provides an overview of the different techniques available to analyse Aβ, such as electron and atomic force microscopy, nuclear magnetic resonance spectroscopy, dye-based assays, size exclusion chromatography, mass spectrometry and SDS-PAGE. The review also explores how different types of Aβ can influence Aβ aggregation and toxicity, leading to variation in experimental outcomes, further highlighting the need for standardisation in Aβ preparations and methods used in current research.
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Affiliation(s)
- Martyna M Matuszyk
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Claire J Garwood
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Laura Ferraiuolo
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Julie E Simpson
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | | | - Stephen B Wharton
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
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6
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Gu L, Guo Z. Lipid membranes induce structural conversion from amyloid oligomers to fibrils. Biochem Biophys Res Commun 2021; 557:122-126. [PMID: 33862455 DOI: 10.1016/j.bbrc.2021.03.174] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 03/31/2021] [Indexed: 12/16/2022]
Abstract
Formation of amyloid oligomers and fibrils underlies the pathogenesis of a number of neurodegenerative diseases such as Alzheimer's. One mechanism of action by which Aβ aggregates cause neuronal toxicity is through interactions with cellular membranes. Aβ aggregates have been shown to disrupt membrane integrity via pore formation, membrane thinning, or lipid extraction. At the same time, lipid membranes also affect the rate of Aβ aggregation and remodel pre-formed Aβ fibrils. Here we show that Aβ42 globulomers, a type of well-characterized and stable Aβ oligomers, convert to amyloid fibrils in the presence of DOPC liposomes. Electron paramagnetic resonance studies show that the fibrils converted from Aβ42 globulomers adopt the same structure as fibrils formed directly from monomers. Our results suggest that the interactions between Aβ oligomers and cellular membranes are dynamic. By converting Aβ oligomers to fibrils, the lipid membrane can reduce the membrane-disrupting activities caused by these oligomers. Modulation of Aβ-membrane interactions as a therapeutic strategy should take into account the dynamic nature of these interactions.
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Affiliation(s)
- Lei Gu
- Department of Neurology, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, CA, 90095, USA
| | - Zhefeng Guo
- Department of Neurology, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, CA, 90095, USA.
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7
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Liu EN, Park G, Nohara J, Guo Z. Effect of spin labelling on the aggregation kinetics of yeast prion protein Ure2. ROYAL SOCIETY OPEN SCIENCE 2021; 8:201747. [PMID: 33959337 PMCID: PMC8074925 DOI: 10.1098/rsos.201747] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 02/10/2021] [Indexed: 06/12/2023]
Abstract
Amyloid formation is involved in a wide range of neurodegenerative diseases including Alzheimer's and prion diseases. Structural understanding of the amyloid is critical to delineate the mechanism of aggregation and its pathological spreading. Site-directed spin labelling has emerged as a powerful structural tool in the studies of amyloid structures and provided structural evidence for the parallel in-register β-sheet structure for a wide range of amyloid proteins. It is generally accepted that spin labelling does not disrupt the structure of the amyloid fibrils, the end product of protein aggregation. The effect on the rate of protein aggregation, however, has not been well characterized. Here, we employed a scanning mutagenesis approach to study the effect of spin labelling on the aggregation rate of 79 spin-labelled variants of the Ure2 prion domain. The aggregation of Ure2 protein is the basis of yeast prion [URE3]. We found that all spin-labelled Ure2 mutants aggregated within the experimental timeframe of 15 to 40 h. Among the 79 spin-labelled positions, only five residue sites (N23, N27, S33, I35 and G42) showed a dramatic delay in the aggregation rate as a result of spin labelling. These positions may be important for fibril nucleation, a rate-limiting step in aggregation. Importantly, spin labelling at most of the sites had a muted effect on Ure2 aggregation kinetics, showing a general tolerance of spin labelling in protein aggregation studies.
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Affiliation(s)
- Emilie N. Liu
- Department of Neurology, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
| | - Giovanna Park
- Department of Neurology, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
| | - Junsuke Nohara
- Department of Neurology, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
| | - Zhefeng Guo
- Department of Neurology, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
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8
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Abedin F, Tatulian SA. Mutual structural effects of unmodified and pyroglutamylated amyloid β peptides during aggregation. J Pept Sci 2021; 27:e3312. [PMID: 33631839 DOI: 10.1002/psc.3312] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 02/05/2021] [Accepted: 02/16/2021] [Indexed: 11/09/2022]
Abstract
Amyloid β (Aβ) peptide aggregates are linked to Alzheimer's disease (AD). Posttranslationally pyroglutamylated Aβ (pEAβ) occurs in AD brains in significant quantities and is hypertoxic, but the underlying structural and aggregation properties remain poorly understood. Here, the structure and aggregation of Aβ1-40 and pEAβ3-40 are analyzed separately and in equimolar combination. Circular dichroism data show that Aβ1-40 , pEAβ3-40 , and their combination assume α-helical structure in dry state and transition to unordered structure in aqueous buffer. Aβ1-40 and the 1:1 combination gradually acquire β-sheet structure while pEAβ3-40 adopts an α-helix/β-sheet conformation. Thioflavin-T fluorescence studies suggest that the two peptides mutually inhibit fibrillogenesis. Fourier transform infrared (FTIR) spectroscopy identifies the presence of β-turn and α-helical structures in addition to β-sheet structure in peptides in aqueous buffer. The kinetics of transitions from the initial α-helical structure to β-sheet structure were resolved by slow hydration of dry peptides by D2 O vapor, coupled with isotope-edited FTIR. These data confirmed the mutual suppression of β-sheet formation by the two peptides. Remarkably, pEAβ3-40 maintained a significant fraction of α-helical structure in the combined sample, implying a reduced β-sheet propensity of pEAβ3-40 . Altogether, the data imply that the combination of unmodified and pyroglutamylated Aβ peptides resists fibrillogenesis and favors the prefibrillar state, which may underlie hypertoxicity of pEAβ.
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Affiliation(s)
- Faisal Abedin
- Physics Graduate Program, University of Central Florida, Orlando, Florida, USA
| | - Suren A Tatulian
- Department of Physics, University of Central Florida, Orlando, Florida, USA
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9
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Rudajev V, Novotny J. The Role of Lipid Environment in Ganglioside GM1-Induced Amyloid β Aggregation. MEMBRANES 2020; 10:membranes10090226. [PMID: 32916822 PMCID: PMC7558528 DOI: 10.3390/membranes10090226] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/04/2020] [Accepted: 09/07/2020] [Indexed: 01/14/2023]
Abstract
Ganglioside GM1 is the most common brain ganglioside enriched in plasma membrane regions known as lipid rafts or membrane microdomains. GM1 participates in many modulatory and communication functions associated with the development, differentiation, and protection of neuronal tissue. It has, however, been demonstrated that GM1 plays a negative role in the pathophysiology of Alzheimer's disease (AD). The two features of AD are the formation of intracellular neurofibrillary bodies and the accumulation of extracellular amyloid β (Aβ). Aβ is a peptide characterized by intrinsic conformational flexibility. Depending on its partners, Aβ can adopt different spatial arrangements. GM1 has been shown to induce specific changes in the spatial organization of Aβ, which lead to enhanced peptide accumulation and deleterious effect especially on neuronal membranes containing clusters of this ganglioside. Changes in GM1 levels and distribution during the development of AD may contribute to the aggravation of the disease.
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10
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Park G, Xue C, Wang H, Guo Z. Distinguishing the Effect on the Rate and Yield of Aβ42 Aggregation by Green Tea Polyphenol EGCG. ACS OMEGA 2020; 5:21497-21505. [PMID: 32905372 PMCID: PMC7469419 DOI: 10.1021/acsomega.0c02063] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 08/10/2020] [Indexed: 05/15/2023]
Abstract
Deposition of Aβ42 aggregates in the form of amyloid plaques is a pathological hallmark of Alzheimer's disease. A desired avenue of intervention is the inhibition of Aβ42 aggregation. Epigallocatechin gallate (EGCG), the main polyphenol in green tea, has been generally considered an inhibitor of Aβ aggregation. However, previous experiments focused on the reduction of the amount of Aβ42 aggregates, while the effect of EGCG on the rate of Aβ42 aggregation was not critically analyzed. Here we performed an experimental evaluation of Aβ42 aggregation kinetics in the absence and presence of EGCG at a wide range of concentrations. We found that EGCG reduced thioflavin T fluorescence in an EGCG concentration-dependent manner, suggesting that EGCG reduced the amount of Aβ42 fibrils. The effect of EGCG on the rate of Aβ42 aggregation appears to be bimodal. We found that higher EGCG-to-Aβ42 ratios promoted the rate of Aβ42 aggregation, while lower EGCG-to-Aβ42 ratios inhibited the aggregation rate. To confirm that the reduction of thioflavin T fluorescence is due to the lowered aggregate quantity, but not due to perturbation of thioflavin T binding to Aβ42 fibrils, we probed the effect of EGCG on Aβ42 aggregation using site-directed spin labeling. Electron paramagnetic resonance of spin-labeled Aβ42 aggregates suggests that high EGCG-to-Aβ42 ratios led to a greatly reduced amount of Aβ42 fibrils, and these aggregates adopt similar structures as the fibrils in the no-EGCG sample. Potential implications of this work in designing prevention or therapeutic strategies using EGCG are discussed.
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11
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Capturing Amyloid-β Oligomers by Stirring with Microscaled Iron Oxide Stir Bars into Magnetic Plaques to Reduce Cytotoxicity toward Neuronal Cells. NANOMATERIALS 2020; 10:nano10071284. [PMID: 32629933 PMCID: PMC7407479 DOI: 10.3390/nano10071284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/24/2020] [Accepted: 06/28/2020] [Indexed: 11/17/2022]
Abstract
Soluble amyloid-β oligomers (oAβ42)-induced neuronal death and inflammation response has been recognized as one of the major causes of Alzheimer’s disease (AD). In this work, a novel strategy adopting silica-coated iron oxide stir bar (MSB)-based AD therapy system via magnetic stirring-induced capture of oAβ42 into magnetic plaques (mpAβ42) and activation of microglia on cellular plaque clearance was developed. With oAβ42 being effectively converted into mpAβ42, the neurotoxicity toward neuronal cells was thus greatly reduced. In addition to the good preservation of neurite outgrowth through the diminished uptake of oAβ42, neurons treated with oAβ42 under magnetic stirring also exhibited comparable neuron-specific protein expression to those in the absence of oAβ42. The phagocytic uptake of mpAβ42 by microglia was enhanced significantly as compared to the counterpart of oAβ42, and the M1 polarization of microglia often occurring after the uptake of oAβ42 restricted to an appreciable extent. As a result, the inflammation induced by pro-inflammatory cytokines was greatly alleviated.
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12
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Talwar P, Kushwaha S, Gupta R, Agarwal R. Systemic Immune Dyshomeostasis Model and Pathways in Alzheimer's Disease. Front Aging Neurosci 2019; 11:290. [PMID: 31736740 PMCID: PMC6838686 DOI: 10.3389/fnagi.2019.00290] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 10/07/2019] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's disease (AD) still remains an enigma for researchers and clinicians. The onset of AD is insidious, gradually progressive and multifactorial. The recent accumulated scientific evidences suggests that the pathological changes resemble the autoimmune-driven self-sustaining inflammatory process as a result of prolonged oxidative stress and immune dyshomeostasis. Apart from aging, during life span various other factors-mainly environmental, lifestyle, chronic stress, polymicrobial infections and neuroendocrine functions-affect the immune system. Here, we provide crosstalk among "trigger insults/inflammatory stimulus" i.e., polymicrobial infection, chronic stress, pro-inflammatory diet and cholinergic signaling to put forward a "Systemic Immune Dyshomeostasis" model as to connect the events leading to AD development and progression. Our model implicates altered cholinergic signaling and suggests pathological stages with various modifiable risk factors and triggers at different chronological age and stage of cognitive decline. The search of specific autoantibodies for AD which may serve as the suitable blood/CSF biomarkers should be actively pursued for the early diagnosis of AD. The preventive and therapeutic strategies should be directed towards maintaining the normal functioning of the immune system throughout the life span and specific modulation of the immune responses in the brain depending on the stage of changes in brain.
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Affiliation(s)
- Puneet Talwar
- Department of Neurology, Institute of Human Behaviour and Allied Sciences (IHBAS), University of Delhi, Delhi, India
| | - Suman Kushwaha
- Department of Neurology, Institute of Human Behaviour and Allied Sciences (IHBAS), University of Delhi, Delhi, India
| | - Renu Gupta
- Department of Microbiology, Institute of Human Behaviour and Allied Sciences (IHBAS), University of Delhi, Delhi, India
| | - Rachna Agarwal
- Department of Neurochemistry, Institute of Human Behaviour and Allied Sciences (IHBAS), University of Delhi, Delhi, India
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