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Al Adem K, Lee S. Structural Polymorphism and Cytotoxicity of Brain-derived β-amyloid Extracts. Protein Sci 2023; 32:e4639. [PMID: 37051675 PMCID: PMC10127262 DOI: 10.1002/pro.4639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 03/04/2023] [Accepted: 04/10/2023] [Indexed: 04/14/2023]
Abstract
To date, more than 37 amyloidogenic proteins have been found to form toxic aggregates that are implicated in the progression of numerous debilitating protein misfolding diseases including Alzheimer's disease (AD). Extensive literature highlights the role of β-amyloid (Aβ) aggregates in causing excessive neuronal cell loss in the brains of AD patients. In fact, major advances in our understanding of Aβ aggregation process, including kinetics, toxicity and structures of fibrillar aggregates have been revealed by examining in vitro preparations of synthetic Aβ peptides. However, ongoing research shows that brain-derived Aβ aggregates have specific characteristics that distinguish them from in vitro prepared species. Notably, the molecular structures of amyloid fibrils grown in the human brain were found to be markedly different than synthetic Aβ fibrils. In addition, recent findings report the existence of heterogeneous Aβ proteoforms in AD brain tissue in contrast to synthetically produced full-length aggregates. Despite their high relevance to AD progression, brain-derived Aβ species are less well-characterized compared with synthetic aggregates. The aim of this review is to provide an overview of the literature on brain-derived Aβ aggregates with particular focus on recent studies that report their structures as well as pathological roles in AD progression. The main motivation of this review is to highlight the importance of utilizing brain-derived amyloids for characterizing the structural and toxic effects of amyloid species. With this knowledge, brain-derived aggregates can be adopted to identify more relevant drug targets and validate potent aggregation inhibitors towards designing highly effective therapeutic strategies against AD. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Kenana Al Adem
- Science Division, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Sungmun Lee
- Department of Biomedical Engineering and Healthcare Engineering Innovation Center, Khalifa University of Science and Technology, Abu Dhabi, UAE
- Khalifa University's Center for Biotechnology, Khalifa University of Science and Technology, Abu Dhabi, UAE
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2
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Behbahanipour M, Benoit R, Navarro S, Ventura S. OligoBinders: Bioengineered Soluble Amyloid-like Nanoparticles to Bind and Neutralize SARS-CoV-2. ACS Appl Mater Interfaces 2023; 15:11444-11457. [PMID: 36890692 PMCID: PMC9969896 DOI: 10.1021/acsami.2c18305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 02/09/2023] [Indexed: 06/18/2023]
Abstract
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has become a primary health concern. Molecules that prevent viral entry into host cells by interfering with the interaction between SARS-CoV-2 spike (S) protein and the human angiotensin-converting enzyme 2 receptor (ACE2r) opened a promising avenue for virus neutralization. Here, we aimed to create a novel kind of nanoparticle that can neutralize SARS-CoV-2. To this purpose, we exploited a modular self-assembly strategy to engineer OligoBinders, soluble oligomeric nanoparticles decorated with two miniproteins previously described to bind to the S protein receptor binding domain (RBD) with high affinity. The multivalent nanostructures compete with the RBD-ACE2r interaction and neutralize SARS-CoV-2 virus-like particles (SC2-VLPs) with IC50 values in the pM range, preventing SC2-VLPs fusion with the membrane of ACE2r-expressing cells. Moreover, OligoBinders are biocompatible and significantly stable in plasma. Overall, we describe a novel protein-based nanotechnology that might find application in SARS-CoV-2 therapeutics and diagnostics.
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Affiliation(s)
- Molood Behbahanipour
- Institut
de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica
i Biologia Molecular, Universitat Autònoma
de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Roger Benoit
- Laboratory
of Nanoscale Biology, Division of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Susanna Navarro
- Institut
de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica
i Biologia Molecular, Universitat Autònoma
de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Salvador Ventura
- Institut
de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica
i Biologia Molecular, Universitat Autònoma
de Barcelona, Bellaterra, 08193 Barcelona, Spain
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3
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Madhu P, Mukhopadhyay S. Distinct types of amyloid-β oligomers displaying diverse neurotoxicity mechanisms in Alzheimer's disease. J Cell Biochem 2021; 122:1594-1608. [PMID: 34494298 DOI: 10.1002/jcb.30141] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/21/2021] [Accepted: 08/26/2021] [Indexed: 11/09/2022]
Abstract
Soluble oligomers of amyloid-β (Aβ) are recognized as key pernicious species in Alzheimer's disease (AD) that cause synaptic dysfunction and memory impairments. Numerous studies have identified various types of Aβ oligomers having heterogeneous peptide length, size distribution, structure, appearance, and toxicity. Here, we review the characteristics of soluble Aβ oligomers based on their morphology, size, and structural reactivity toward the conformation-specific antibodies and then describe their formation, localization, and cellular effects in AD brains, in vivo and in vitro. We also summarize the mechanistic pathways by which these soluble Aβ oligomers cause proteasomal impairment, calcium dyshomeostasis, inhibition of long-term potentiation, apoptosis, mitochondrial damage, and cognitive decline. These cellular events include three distinct molecular mechanisms: (i) high-affinity binding with the receptors for Aβ oligomers such as N-methyl- d-aspartate receptors, cellular prion protein, nerve growth factor, insulin receptors, and frizzled receptors; (ii) the interaction of Aβ oligomers with the lipid membranes; (iii) intraneuronal accumulation of Aβ by α7-nicotinic acetylcholine receptors, apolipoprotein E, and receptor for advanced glycation end products. These studies indicate that there is a pressing need to carefully examine the role of size, appearance, and the conformation of oligomers in identifying the specific mechanism of neurotoxicity that may uncover potential targets for designing AD therapeutics.
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Affiliation(s)
- Priyanka Madhu
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER), Mohali, India.,Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, India
| | - Samrat Mukhopadhyay
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER), Mohali, India.,Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, India.,Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali, India
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4
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Abstract
The loss of proteostasis over the life course is associated with a wide range of debilitating degenerative diseases and is a central hallmark of human aging. When left unchecked, proteins that are intrinsically disordered can pathologically aggregate into highly ordered fibrils, plaques, and tangles (termed amyloids), which are associated with countless disorders such as Alzheimer's disease, Parkinson's disease, type II diabetes, cancer, and even certain viral infections. However, despite significant advances in protein folding and solution biophysics techniques, determining the molecular cause of these conditions in humans has remained elusive. This has been due, in part, to recent discoveries showing that soluble protein oligomers, not insoluble fibrils or plaques, drive the majority of pathological processes. This has subsequently led researchers to focus instead on heterogeneous and often promiscuous protein oligomers. Unfortunately, significant gaps remain in how to prepare, model, experimentally corroborate, and extract amyloid oligomers relevant to human disease in a systematic manner. This Review will report on each of these techniques and their successes and shortcomings in an attempt to standardize comparisons between protein oligomers across disciplines, especially in the context of neurodegeneration. By standardizing multiple techniques and identifying their common overlap, a clearer picture of the soluble neuropathological aggresome can be constructed and used as a baseline for studying human disease and aging.
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Affiliation(s)
- Gregory-Neal Gomes
- Department of Pathology, Yale School of Medicine, New Haven, CT, 06520, USA
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Zachary A. Levine
- Department of Pathology, Yale School of Medicine, New Haven, CT, 06520, USA
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06511, USA
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5
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Foley AR, Finn TS, Kung T, Hatami A, Lee HW, Jia M, Rolandi M, Raskatov JA. Trapping and Characterization of Nontoxic Aβ42 Aggregation Intermediates. ACS Chem Neurosci 2019; 10:3880-3887. [PMID: 31319029 DOI: 10.1021/acschemneuro.9b00340] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Amyloid β (Aβ) 42 is an aggregation-prone peptide and the believed seminal etiological agent of Alzheimer's disease (AD). Intermediates of Aβ42 aggregation, commonly referred to as diffusible oligomers, are considered to be among the most toxic forms of the peptide. Here, we studied the effect of the age-related epimerization of Ser26 (i.e., S26s chiral edit) in Aβ42 and discovered that this subtle molecular change led to reduced fibril formation propensity. Surprisingly, the resultant soluble aggregates were nontoxic. To gain insight into the structural changes that occurred in the peptide upon S26s substitution, the system was probed using an array of biophysical and biochemical methods. These experiments consistently pointed to the stabilization of aggregation intermediates in the Aβ42-S26s system. To better understand the changes arising as a consequence of the S26s substitution, molecular level structural studies were performed. Using a combined nuclear magnetic resonance (NMR)- and density functional theory (DFT)-computational approach, we found that the S26s chiral edit induced only local structural changes in the Gly25-Ser26-Asn27 region. Interestingly, these subtle changes enabled the formation of an intramolecular Ser26-Asn27 H-bond, which disrupted the ability of Asn27 to engage in the fibrillogenic side chain-to-side chain H-bonding pattern. This reveals that intermolecular stabilizing interactions between Asn27 side chains are a key element controlling Aβ42 aggregation and toxicity.
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Affiliation(s)
- Alejandro R. Foley
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California 95064, United States
| | - Thomas S. Finn
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California 95064, United States
| | - Timothy Kung
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California 95064, United States
| | - Asa Hatami
- Sangamo Therapeutics, Richmond, California 94804, United States
| | - Hsiau-Wei Lee
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California 95064, United States
| | - Manping Jia
- Department of Electrical Engineering, University of California Santa Cruz, Santa Cruz, California 95064, United States
| | - Marco Rolandi
- Department of Electrical Engineering, University of California Santa Cruz, Santa Cruz, California 95064, United States
| | - Jevgenij A. Raskatov
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California 95064, United States
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6
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Silva A, Sárkány Z, Fraga JS, Taboada P, Macedo-Ribeiro S, Martins PM. Probing the Occurrence of Soluble Oligomers through Amyloid Aggregation Scaling Laws. Biomolecules 2018; 8:biom8040108. [PMID: 30287796 PMCID: PMC6316134 DOI: 10.3390/biom8040108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 09/29/2018] [Accepted: 10/01/2018] [Indexed: 12/24/2022] Open
Abstract
Drug discovery frequently relies on the kinetic analysis of physicochemical reactions that are at the origin of the disease state. Amyloid fibril formation has been extensively investigated in relation to prevalent and rare neurodegenerative diseases, but thus far no therapeutic solution has directly arisen from this knowledge. Other aggregation pathways producing smaller, hard-to-detect soluble oligomers are increasingly appointed as the main reason for cell toxicity and cell-to-cell transmissibility. Here we show that amyloid fibrillation kinetics can be used to unveil the protein oligomerization state. This is illustrated for human insulin and ataxin-3, two model proteins for which the amyloidogenic and oligomeric pathways are well characterized. Aggregation curves measured by the standard thioflavin-T (ThT) fluorescence assay are shown to reflect the relative composition of protein monomers and soluble oligomers measured by nuclear magnetic resonance (NMR) for human insulin, and by dynamic light scattering (DLS) for ataxin-3. Unconventional scaling laws of kinetic measurables were explained using a single set of model parameters consisting of two rate constants, and in the case of ataxin-3, an additional order-of-reaction. The same fitted parameters were used in a discretized population balance that adequately describes time-course measurements of fibril size distributions. Our results provide the opportunity to study oligomeric targets using simple, high-throughput compatible, biophysical assays.
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Affiliation(s)
- Alexandra Silva
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.
| | - Zsuzsa Sárkány
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.
| | - Joana S Fraga
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.
- ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4050-313 Porto, Portugal.
| | - Pablo Taboada
- Área de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
- Instituto de Investigación Sanitaria (IDIS), 15706 de Santiago de Compostela, Spain.
| | - Sandra Macedo-Ribeiro
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.
| | - Pedro M Martins
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.
- ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4050-313 Porto, Portugal.
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7
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Silva A, Almeida B, Fraga JS, Taboada P, Martins PM, Macedo-Ribeiro S. Distribution of Amyloid-Like and Oligomeric Species from Protein Aggregation Kinetics. Angew Chem Int Ed Engl 2017; 56:14042-14045. [PMID: 28906069 DOI: 10.1002/anie.201707345] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Indexed: 12/13/2022]
Abstract
Amyloid fibrils and soluble oligomers are two types of protein aggregates associated with neurodegeneration. Classic therapeutic strategies try to prevent the nucleation and spread of amyloid fibrils, whilst diffusible oligomers have emerged as promising drug targets affecting downstream pathogenic processes. We developed a generic protein aggregation model and validate it against measured compositions of fibrillar and non-fibrillar assemblies of ataxin-3, a protein implicated in Machado-Joseph disease. The derived analytic rate-law equations can be used to 1) identify the presence of parallel aggregation pathways and 2) estimate the critical sizes of amyloid fibrils. The discretized population balance supporting our model is the first to quantitatively fit time-resolved measurements of size and composition of both amyloid-like and oligomeric species. The new theoretical framework can be used to screen a new class of drugs specifically targeting toxic oligomers.
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Affiliation(s)
- Alexandra Silva
- IBMC-Instituto de Biologia Molecular e Celular and I3s-Instituto de Investigação e Inovação em Saúde Portugal, Universidade do Porto, 4150-180, Porto, Portugal
| | - Bruno Almeida
- IBMC-Instituto de Biologia Molecular e Celular and I3s-Instituto de Investigação e Inovação em Saúde Portugal, Universidade do Porto, 4150-180, Porto, Portugal.,Present address: Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, University of Minho, Braga/Guimarães, Portugal
| | - Joana S Fraga
- IBMC-Instituto de Biologia Molecular e Celular and I3s-Instituto de Investigação e Inovação em Saúde Portugal, Universidade do Porto, 4150-180, Porto, Portugal
| | - Pablo Taboada
- Área de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, Instituto de Investigación Sanitaria (IDIS) de Santiago de Compostela, Spain
| | - Pedro M Martins
- IBMC-Instituto de Biologia Molecular e Celular and I3s-Instituto de Investigação e Inovação em Saúde Portugal, Universidade do Porto, 4150-180, Porto, Portugal.,LEPABE-Departamento de Engenharia Química, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal.,ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Portugal
| | - Sandra Macedo-Ribeiro
- IBMC-Instituto de Biologia Molecular e Celular and I3s-Instituto de Investigação e Inovação em Saúde Portugal, Universidade do Porto, 4150-180, Porto, Portugal
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8
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Pavlova A, Cheng CY, Kinnebrew M, Lew J, Dahlquist FW, Han S. Protein structural and surface water rearrangement constitute major events in the earliest aggregation stages of tau. Proc Natl Acad Sci U S A 2016; 113:E127-36. [PMID: 26712030 DOI: 10.1073/pnas.1504415113] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein aggregation plays a critical role in the pathogenesis of neurodegenerative diseases, and the mechanism of its progression is poorly understood. Here, we examine the structural and dynamic characteristics of transiently evolving protein aggregates under ambient conditions by directly probing protein surface water diffusivity, local protein segment dynamics, and interprotein packing as a function of aggregation time, along the third repeat domain and C terminus of Δtau187 spanning residues 255-441 of the longest isoform of human tau. These measurements were achieved with a set of highly sensitive magnetic resonance tools that rely on site-specific electron spin labeling of Δtau187. Within minutes of initiated aggregation, the majority of Δtau187 that is initially homogeneously hydrated undergoes structural transformations to form partially structured aggregation intermediates. This is reflected in the dispersion of surface water dynamics that is distinct around the third repeat domain, found to be embedded in an intertau interface, from that of the solvent-exposed C terminus. Over the course of hours and in a rate-limiting process, a majority of these aggregation intermediates proceed to convert into stable β-sheet structured species and maintain their stacking order without exchanging their subunits. The population of β-sheet structured species is >5% within 5 min of aggregation and gradually grows to 50-70% within the early stages of fibril formation, while they mostly anneal block-wisely to form elongated fibrils. Our findings suggest that the formation of dynamic aggregation intermediates constitutes a major event occurring in the earliest stages of tau aggregation that precedes, and likely facilitates, fibril formation and growth.
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David MA, Tayebi M. Detection of protein aggregates in brain and cerebrospinal fluid derived from multiple sclerosis patients. Front Neurol 2014; 5:251. [PMID: 25520699 PMCID: PMC4252634 DOI: 10.3389/fneur.2014.00251] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 11/13/2014] [Indexed: 02/01/2023] Open
Abstract
Studies of the properties of soluble oligomer species of amyloidogenic proteins, derived from different proteins with little sequence homology, have indicated that they share a common structure and may share similar pathogenic mechanisms. Amyloid β, tau protein, as well as amyloid precursor protein normally associated with Alzheimer’s disease and Parkinson’s disease were found in lesions and plaques of multiple sclerosis patients. The objective of the study is to investigate whether brain and cerebrospinal fluid (CSF) samples derived from multiple sclerosis patients demonstrate the presence of soluble oligomers normally associated with protein-misfolding diseases such as Alzheimer’s disease. We have used anti-oligomer monoclonal antibodies to immunodetect soluble oligomers in CSF and brain tissues derived from multiple sclerosis patients. In this report, we describe the presence of soluble oligomers in the brain tissue and cerebral spinal fluid of multiple sclerosis patients detected with our monoclonal anti-oligomer antibodies with Western blot and Sandwich enzyme-linked immunosorbent assay (sELISA). These results might suggest that protein aggregation plays a role in multiple sclerosis pathogenesis although further and more refined studies are needed to confirm the role of soluble aggregates in multiple sclerosis.
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Affiliation(s)
- Monique Antoinette David
- Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, University of Texas Houston Medical School , Houston, TX , USA ; Antibody Discovery Laboratory, PrioCam , Houston, TX , USA
| | - Mourad Tayebi
- Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, University of Texas Houston Medical School , Houston, TX , USA ; Department of Pathology and Infectious Diseases, Faculty of Health and Medical Sciences, University of Surrey , Guildford , UK
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Berhanu WM, Hansmann UHE. The stability of cylindrin β-barrel amyloid oligomer models-a molecular dynamics study. Proteins 2013; 81:1542-55. [PMID: 23606599 DOI: 10.1002/prot.24302] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Revised: 03/21/2013] [Accepted: 04/01/2013] [Indexed: 11/10/2022]
Abstract
Small-soluble amyloid oligomers are believed to play a significant role in the pathology of amyloid diseases. Recently, the atomic structure of a toxic oligomer formed by an 11 residue and its tandem repeat was found to have an out-off register antiparallel β-strands in the shape of a β-barrel. In the present article we investigate the effect of mutations in the hydrophobic cores on the structure and dynamic of the β-barrels using all atom multiple molecular dynamics simulations with an explicit solvent. Extending previous experiments with molecular dynamics simulations we systematically test how stability and formation of cylindrin depends on the interplay between hydrophobicity and steric effects of the core residues. We find that strong hydrophobic interactions between geometrically fitting residues keep the strands (both in register and out-off-register interface) in close proximity, which in turn stabilizes the side-chain and main-chain hydrogen bonds, and the salt bridges on the outer surface along the weak out-of-register interface. Our simulations also indicate presence of water molecules in the hydrophobic interior of the cylindrin β-barrel.Proteins 2013.
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Affiliation(s)
- Workalemahu M Berhanu
- Department of Chemistry & Biochemistry, University of Oklahoma, Norman, Oklahoma, 73019
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