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Huang F, Yan J, Zhang X, Xu H, Lian J, Yang X, Wang C, Ding F, Sun Y. Computational insights into the aggregation mechanism and amyloidogenic core of aortic amyloid medin polypeptide. Colloids Surf B Biointerfaces 2024; 244:114192. [PMID: 39226847 DOI: 10.1016/j.colsurfb.2024.114192] [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: 05/24/2024] [Revised: 07/30/2024] [Accepted: 08/29/2024] [Indexed: 09/05/2024]
Abstract
Medin amyloid, prevalent in the vessel walls of 97 % of individuals over 50, contributes to arterial stiffening and cerebrovascular dysfunction, yet our understanding of its aggregation mechanism remains limited. Dividing the full-length 50-amino-acid medin peptide into five 10-residue segments, we conducted individual investigations on each segment's self-assembly dynamics via microsecond-timescale atomistic discrete molecular dynamics (DMD) simulations. Our findings showed that medin1-10 and medin11-20 segments predominantly existed as isolated unstructured monomers, unable to form stable oligomers. Medin31-40 exhibited moderate aggregation, forming dynamic β-sheet oligomers with frequent association and dissociation. Conversely, medin21-30 and medin41-50 segments demonstrated significant self-assembly capability, readily forming stable β-sheet-rich oligomers. Residue pairwise contact frequency analysis highlighted the critical roles of residues 22-26 and 43-49 in driving the self-assembly of medin21-30 and medin41-50, acting as the β-sheet core and facilitating β-strand formation in other regions within medin monomers, expecting to extend to oligomers and fibrils. Regions containing residues 22-26 and 43-49, with substantial self-assembly abilities and assistance in β-sheet formation, represent crucial targets for amyloid inhibitor drug design against aortic medial amyloidosis (AMA). In summary, our study not only offers deep insights into the mechanism of medin amyloid formation but also provides crucial theoretical and practical guidance for future treatments of AMA.
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Affiliation(s)
- Fengjuan Huang
- Ningbo Institute of Innovation for Combined Medicine and Engineering (NIIME), Ningbo Medical Center Lihuili Hospital, Ningbo 315211, China
| | - Jiajia Yan
- School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
| | - Xiaohan Zhang
- School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
| | - Huan Xu
- School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
| | - Jiangfang Lian
- Ningbo Institute of Innovation for Combined Medicine and Engineering (NIIME), Ningbo Medical Center Lihuili Hospital, Ningbo 315211, China
| | - Xi Yang
- Ningbo Institute of Innovation for Combined Medicine and Engineering (NIIME), Ningbo Medical Center Lihuili Hospital, Ningbo 315211, China
| | - Chuang Wang
- School of Medicine, Ningbo University, Ningbo 315211, China.
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States.
| | - Yunxiang Sun
- School of Physical Science and Technology, Ningbo University, Ningbo 315211, China; Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States.
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2
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Altenburg IS, Smets NG, Strijkers GJ, Bakker EN. Medin, a link between vascular pathology and dementia? J Cereb Blood Flow Metab 2024:271678X241289772. [PMID: 39370976 DOI: 10.1177/0271678x241289772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/08/2024]
Abstract
Medin is a protein fragment derived from milk fat globule epidermal growth factor VIII (MFG-E8). Medin aggregates are present in the vessel wall of most subjects over 50 years of age. In this narrative review, we focus on the consequences of medin aggregation in relation to the development of dementia. Recent literature revealed medin as biomarker for dementia in CSF, specifically of a vascular subtype. Preclinical work showed that medin is associated with aging-related cerebral vascular dysfunction, vascular stiffening, hypertension, and. vascular amyloid β deposition. These findings position medin as a potential mechanistic link between aging, vascular pathology and dementia.
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Affiliation(s)
- Ilse S Altenburg
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Nina G Smets
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences Research Institute, Amsterdam, The Netherlands
- Amsterdam Neuroscience Research Institute, Amsterdam, The Netherlands
| | - Gustav J Strijkers
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences Research Institute, Amsterdam, The Netherlands
| | - Erik Ntp Bakker
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences Research Institute, Amsterdam, The Netherlands
- Amsterdam Neuroscience Research Institute, Amsterdam, The Netherlands
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3
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Rios FJ, de Ciuceis C, Georgiopoulos G, Lazaridis A, Nosalski R, Pavlidis G, Tual-Chalot S, Agabiti-Rosei C, Camargo LL, Dąbrowska E, Quarti-Trevano F, Hellmann M, Masi S, Lopreiato M, Mavraganis G, Mengozzi A, Montezano AC, Stavropoulos K, Winklewski PJ, Wolf J, Costantino S, Doumas M, Gkaliagkousi E, Grassi G, Guzik TJ, Ikonomidis I, Narkiewicz K, Paneni F, Rizzoni D, Stamatelopoulos K, Stellos K, Taddei S, Touyz RM, Virdis A. Mechanisms of Vascular Inflammation and Potential Therapeutic Targets: A Position Paper From the ESH Working Group on Small Arteries. Hypertension 2024; 81:1218-1232. [PMID: 38511317 DOI: 10.1161/hypertensionaha.123.22483] [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: 03/22/2024]
Abstract
Inflammatory responses in small vessels play an important role in the development of cardiovascular diseases, including hypertension, stroke, and small vessel disease. This involves various complex molecular processes including oxidative stress, inflammasome activation, immune-mediated responses, and protein misfolding, which together contribute to microvascular damage. In addition, epigenetic factors, including DNA methylation, histone modifications, and microRNAs influence vascular inflammation and injury. These phenomena may be acquired during the aging process or due to environmental factors. Activation of proinflammatory signaling pathways and molecular events induce low-grade and chronic inflammation with consequent cardiovascular damage. Identifying mechanism-specific targets might provide opportunities in the development of novel therapeutic approaches. Monoclonal antibodies targeting inflammatory cytokines and epigenetic drugs, show promise in reducing microvascular inflammation and associated cardiovascular diseases. In this article, we provide a comprehensive discussion of the complex mechanisms underlying microvascular inflammation and offer insights into innovative therapeutic strategies that may ameliorate vascular injury in cardiovascular disease.
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Affiliation(s)
- Francisco J Rios
- Research Institute of the McGill University Health Centre, McGill University, Montreal, Canada (F.J.R., L.L.C., A.C.M., R.M.T.)
| | - Carolina de Ciuceis
- Department of Clinical and Experimental Sciences, University of Brescia (C.d.C., C.A.-R., D.R.)
| | - Georgios Georgiopoulos
- Angiology and Endothelial Pathophysiology Unit, Department of Clinical Therapeutics, Medical School (G.G., G.M., K. Stamatelopoulos), National and Kapodistrian University of Athens
| | - Antonios Lazaridis
- Third Department of Internal Medicine, Aristotle University of Thessaloniki, Papageorgiou Hospital, Greece (A.L., E.G.)
| | - Ryszard Nosalski
- Centre for Cardiovascular Sciences; Queen's Medical Research Institute, University of Edinburgh, United Kingdom (R.N., T.J.G.)
- Department of Internal Medicine, Center for Medical Genomics OMICRON, Jagiellonian University Medical College, Krakow, Poland (R.N., T.J.G.)
| | - George Pavlidis
- Medical School (G.P., I.I.), National and Kapodistrian University of Athens
- Preventive Cardiology Laboratory and Clinic of Cardiometabolic Diseases, 2-Cardiology Department, Attikon Hospital, Athens, Greece (G.P., I.I.)
| | - Simon Tual-Chalot
- Biosciences Institute, Vascular Biology and Medicine Theme, Faculty of Medical Sciences, Newcastle University, United Kingdom (S.T.-C., K. Stellos)
| | - Claudia Agabiti-Rosei
- Department of Clinical and Experimental Sciences, University of Brescia (C.d.C., C.A.-R., D.R.)
| | - Livia L Camargo
- Research Institute of the McGill University Health Centre, McGill University, Montreal, Canada (F.J.R., L.L.C., A.C.M., R.M.T.)
| | - Edyta Dąbrowska
- Department of Hypertension and Diabetology, Center of Translational Medicine (E.D., J.W., K.N.) and M.D.)
| | - Fosca Quarti-Trevano
- Clinica Medica, Department of Medicine and Surgery, University of Milano-Bicocca, Milan, Italy (F.Q.-T., G.G.)
| | - Marcin Hellmann
- Cardiac Diagnostics (M.H.), Medical University of Gdansk, Poland
| | - Stefano Masi
- Institute of Cardiovascular Science, University College London, United Kingdom (S.M.)
- Department of Clinical and Experimental Medicine, University of Pisa, Italy (S.M., M.L., A.M., S.T., A.V.)
| | - Mariarosaria Lopreiato
- Department of Clinical and Experimental Medicine, University of Pisa, Italy (S.M., M.L., A.M., S.T., A.V.)
| | - Georgios Mavraganis
- Angiology and Endothelial Pathophysiology Unit, Department of Clinical Therapeutics, Medical School (G.G., G.M., K. Stamatelopoulos), National and Kapodistrian University of Athens
| | - Alessandro Mengozzi
- Department of Clinical and Experimental Medicine, University of Pisa, Italy (S.M., M.L., A.M., S.T., A.V.)
- Center for Translational and Experimental Cardiology, Department of Cardiology, University Hospital Zurich, University of Zurich, Switzerland (A.M., F.P.)
- Health Science Interdisciplinary Center, Scuola Superiore Sant'Anna, Pisa (A.M.)
| | - Augusto C Montezano
- Research Institute of the McGill University Health Centre, McGill University, Montreal, Canada (F.J.R., L.L.C., A.C.M., R.M.T.)
| | - Konstantinos Stavropoulos
- Second Medical Department, Hippokration Hospital, Aristotle University of Thessaloniki, Greece (K. Stavropoulos)
| | - Pawel J Winklewski
- Departments of Human Physiology (P.J.W.), Medical University of Gdansk, Poland
| | - Jacek Wolf
- Department of Hypertension and Diabetology, Center of Translational Medicine (E.D., J.W., K.N.) and M.D.)
| | - Sarah Costantino
- University Heart Center (S.C., F.P.), University Hospital Zurich, Switzerland
| | - Michael Doumas
- Department of Hypertension and Diabetology, Center of Translational Medicine (E.D., J.W., K.N.) and M.D.)
| | - Eugenia Gkaliagkousi
- Third Department of Internal Medicine, Aristotle University of Thessaloniki, Papageorgiou Hospital, Greece (A.L., E.G.)
| | - Guido Grassi
- Clinica Medica, Department of Medicine and Surgery, University of Milano-Bicocca, Milan, Italy (F.Q.-T., G.G.)
| | - Tomasz J Guzik
- Centre for Cardiovascular Sciences; Queen's Medical Research Institute, University of Edinburgh, United Kingdom (R.N., T.J.G.)
- Department of Internal Medicine, Center for Medical Genomics OMICRON, Jagiellonian University Medical College, Krakow, Poland (R.N., T.J.G.)
| | - Ignatios Ikonomidis
- Medical School (G.P., I.I.), National and Kapodistrian University of Athens
- Preventive Cardiology Laboratory and Clinic of Cardiometabolic Diseases, 2-Cardiology Department, Attikon Hospital, Athens, Greece (G.P., I.I.)
| | - Krzysztof Narkiewicz
- Department of Hypertension and Diabetology, Center of Translational Medicine (E.D., J.W., K.N.) and M.D.)
| | - Francesco Paneni
- Center for Translational and Experimental Cardiology, Department of Cardiology, University Hospital Zurich, University of Zurich, Switzerland (A.M., F.P.)
- University Heart Center (S.C., F.P.), University Hospital Zurich, Switzerland
- Department of Research and Education (F.P.), University Hospital Zurich, Switzerland
| | - Damiano Rizzoni
- Department of Clinical and Experimental Sciences, University of Brescia (C.d.C., C.A.-R., D.R.)
- Division of Medicine, Spedali Civili di Brescia, Italy (D.R.)
| | - Kimon Stamatelopoulos
- Angiology and Endothelial Pathophysiology Unit, Department of Clinical Therapeutics, Medical School (G.G., G.M., K. Stamatelopoulos), National and Kapodistrian University of Athens
| | - Konstantinos Stellos
- Biosciences Institute, Vascular Biology and Medicine Theme, Faculty of Medical Sciences, Newcastle University, United Kingdom (S.T.-C., K. Stellos)
- Department of Cardiovascular Research, European Center for Angioscience, Medical Faculty Mannheim (K. Stellos), Heidelberg University, Germany
- Department of Cardiology, University Hospital Mannheim (K. Stellos), Heidelberg University, Germany
- German Centre for Cardiovascular Research, Heidelberg/Mannheim Partner Site (K. Stellos)
| | - Stefano Taddei
- Department of Clinical and Experimental Medicine, University of Pisa, Italy (S.M., M.L., A.M., S.T., A.V.)
| | - Rhian M Touyz
- Research Institute of the McGill University Health Centre, McGill University, Montreal, Canada (F.J.R., L.L.C., A.C.M., R.M.T.)
| | - Agostino Virdis
- Department of Clinical and Experimental Medicine, University of Pisa, Italy (S.M., M.L., A.M., S.T., A.V.)
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Madine J, Davies HA, Migrino RQ, Ruotsalainen SE, Wagner J, Neher JJ. Medin amyloid may drive arterial aging and disease in the periphery and brain. NATURE AGING 2023; 3:1039-1041. [PMID: 37620584 DOI: 10.1038/s43587-023-00481-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Affiliation(s)
- Jillian Madine
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Hannah A Davies
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Raymond Q Migrino
- Phoenix Veterans Affairs Health Care System and University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Sanni E Ruotsalainen
- Institute for Molecular Medicine Finland (FIMM), HiLIFE, University of Helsinki, Helsinki, Finland
| | - Jessica Wagner
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Jonas J Neher
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany.
- Department of Cellular Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.
- Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, LMU Munich, Munich, Germany.
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Milk Fat Globule Epidermal Growth Factor VIII Fragment Medin in Age-Associated Arterial Adverse Remodeling and Arterial Disease. Cells 2023; 12:cells12020253. [PMID: 36672188 PMCID: PMC9857039 DOI: 10.3390/cells12020253] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/28/2022] [Accepted: 01/03/2023] [Indexed: 01/11/2023] Open
Abstract
Medin, a small 50-amino acid peptide, is an internal cleaved product from the second discoidin domain of milk fat globule epidermal growth factor VIII (MFG-E8) protein. Medin has been reported as the most common amylogenic protein in the upper part of the arterial system, including aortic, temporal, and cerebral arterial walls in the elderly. Medin has a high affinity to elastic fibers and is closely associated with arterial degenerative inflammation, elastic fiber fragmentation, calcification, and amyloidosis. In vitro, treating with the medin peptide promotes the inflammatory phenotypic shift of both endothelial cells and vascular smooth muscle cells. In vitro, ex vivo, and in vivo studies demonstrate that medin enhances the abundance of reactive oxygen species and reactive nitrogen species produced by both endothelial cells and vascular smooth muscle cells and promotes vascular endothelial dysfunction and arterial stiffening. Immunostaining and immunoblotting analyses of human samples indicate that the levels of medin are increased in the pathogenesis of aortic aneurysm/dissection, temporal arteritis, and cerebrovascular dementia. Thus, medin peptide could be targeted as a biomarker diagnostic tool or as a potential molecular approach to curbing the arterial degenerative inflammatory remodeling that accompanies aging and disease.
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6
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Quittot N, Fortier M, Babych M, Nguyen PT, Sebastiao M, Bourgault S. Cell surface glycosaminoglycans exacerbate plasma membrane perturbation induced by the islet amyloid polypeptide. FASEB J 2021; 35:e21306. [DOI: 10.1096/fj.202001845r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/14/2020] [Accepted: 12/09/2020] [Indexed: 11/11/2022]
Affiliation(s)
- Noé Quittot
- Department of Chemistry Université du Québec à Montréal Montreal QC Canada
- Center of Excellence in Research on Orphan Diseases ‐ Courtois Foundation Montreal Canada
- Quebec Network for Research on Protein Function, Engineering and Applications, PROTEO Quebec City Canada
| | - Mathilde Fortier
- Department of Chemistry Université du Québec à Montréal Montreal QC Canada
- Center of Excellence in Research on Orphan Diseases ‐ Courtois Foundation Montreal Canada
- Quebec Network for Research on Protein Function, Engineering and Applications, PROTEO Quebec City Canada
| | - Margaryta Babych
- Department of Chemistry Université du Québec à Montréal Montreal QC Canada
- Center of Excellence in Research on Orphan Diseases ‐ Courtois Foundation Montreal Canada
- Quebec Network for Research on Protein Function, Engineering and Applications, PROTEO Quebec City Canada
| | - Phuong Trang Nguyen
- Department of Chemistry Université du Québec à Montréal Montreal QC Canada
- Center of Excellence in Research on Orphan Diseases ‐ Courtois Foundation Montreal Canada
- Quebec Network for Research on Protein Function, Engineering and Applications, PROTEO Quebec City Canada
| | - Mathew Sebastiao
- Department of Chemistry Université du Québec à Montréal Montreal QC Canada
- Center of Excellence in Research on Orphan Diseases ‐ Courtois Foundation Montreal Canada
- Quebec Network for Research on Protein Function, Engineering and Applications, PROTEO Quebec City Canada
| | - Steve Bourgault
- Department of Chemistry Université du Québec à Montréal Montreal QC Canada
- Center of Excellence in Research on Orphan Diseases ‐ Courtois Foundation Montreal Canada
- Quebec Network for Research on Protein Function, Engineering and Applications, PROTEO Quebec City Canada
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7
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Ni YQ, Zhan JK, Liu YS. Roles and mechanisms of MFG-E8 in vascular aging-related diseases. Ageing Res Rev 2020; 64:101176. [PMID: 32971257 DOI: 10.1016/j.arr.2020.101176] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 08/17/2020] [Accepted: 09/03/2020] [Indexed: 12/20/2022]
Abstract
The aging of the vasculature plays a crucial role in the pathological progression of various vascular aging-related diseases. As endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are essential parts in the inner and medial layers of vessel wall, respectively, the structural and functional alterations of ECs and VSMCs are the major causes of vascular aging. Milk fat globule-epidermal growth factor 8 (MFG-E8) is a multifunctional glycoprotein which exerts a regulatory role in the intercellular interactions involved in a variety of biological and pathological processes. Emerging evidence suggests that MFG-E8 is a novel and outstanding modulator for vascular aging via targeting at ECs and VSMCs. In this review, we will summarise the cumulative roles and mechanisms of MFG-E8 in vascular aging and vascular aging-related diseases with special emphasis on the functions of ECs and VSMCs. In addition, we also aim to focus on the promising diagnostic function as a biomarker and the potential therapeutic application of MFG-E8 in vascular aging and the clinical evaluation of vascular aging-related diseases.
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8
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Medin aggregation causes cerebrovascular dysfunction in aging wild-type mice. Proc Natl Acad Sci U S A 2020; 117:23925-23931. [PMID: 32900929 DOI: 10.1073/pnas.2011133117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Medin is the most common amyloid known in humans, as it can be found in blood vessels of the upper body in virtually everybody over 50 years of age. However, it remains unknown whether deposition of Medin plays a causal role in age-related vascular dysfunction. We now report that aggregates of Medin also develop in the aorta and brain vasculature of wild-type mice in an age-dependent manner. Strikingly, genetic deficiency of the Medin precursor protein, MFG-E8, eliminates not only vascular aggregates but also prevents age-associated decline of cerebrovascular function in mice. Given the prevalence of Medin aggregates in the general population and its role in vascular dysfunction with aging, targeting Medin may become a novel approach to sustain healthy aging.
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Davies HA, Caamaño-Gutiérrez E, Chim YH, Field M, Nawaytou O, Ressel L, Akhtar R, Madine J. Idiopathic degenerative thoracic aneurysms are associated with increased aortic medial amyloid. Amyloid 2019; 26:148-155. [PMID: 31210552 PMCID: PMC6816484 DOI: 10.1080/13506129.2019.1625323] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 05/20/2019] [Accepted: 05/27/2019] [Indexed: 02/06/2023]
Abstract
Objective: To explore the relationship of aortic medial amyloid with biochemical and micromechanical properties of the aortic wall in aneurysm patients. Methods: Human aortic tissues removed during aneurysm surgery from tricuspid (idiopathic degenerative aneurysm, DA) and bicuspid valve (BAV) patients were subjected to oscillatory nanoindentation experiments to determine localised mechanical properties of the tissue (shear storage modulus, G´ and shear loss modulus, G˝). Collagen, elastin, matrix metalloproteinase 2 and glycosaminoglycans concentrations were determined, along with relative levels of aortic medial amyloid-related factors (medin, milk fat globule-EGF factor 8, oligomers and fibrils). Measurements were combined with clinical data and statistical analyses performed. Results: The DA cohort can be divided based on their phenotype. One group shared similar characteristics with BAV patients, termed bicuspid like phenotype-tricuspid valve. The second group had high amyloid oligomer species present with a significantly lower G´ (p = .01), indicative of reduced elastic response of the tissue, termed amyloid-rich. Conclusions: We identified a group of DA patients with high amyloid oligomers and altered micromechanical and structural properties of the vessel wall. We propose these findings as a cause for aneurysm formation in these patients. Amyloid is not found in BAV patients, suggesting at least two distinct mechanisms for pathogenesis.
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Affiliation(s)
- Hannah A. Davies
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Eva Caamaño-Gutiérrez
- Computational Biology Facility, Technology Directorate, University of Liverpool, Liverpool, UK
| | - Ya Hua Chim
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, Liverpool, UK
| | - Mark Field
- Liverpool Heart and Chest Hospital, Liverpool, UK
| | | | - Lorenzo Ressel
- Department of Veterinary Pathology and Public Health, Institute of Veterinary Science, University of Liverpool, Liverpool, UK
| | - Riaz Akhtar
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, Liverpool, UK
| | - Jillian Madine
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
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Owen MC, Gnutt D, Gao M, Wärmländer SKTS, Jarvet J, Gräslund A, Winter R, Ebbinghaus S, Strodel B. Effects of in vivo conditions on amyloid aggregation. Chem Soc Rev 2019; 48:3946-3996. [PMID: 31192324 DOI: 10.1039/c8cs00034d] [Citation(s) in RCA: 123] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
One of the grand challenges of biophysical chemistry is to understand the principles that govern protein misfolding and aggregation, which is a highly complex process that is sensitive to initial conditions, operates on a huge range of length- and timescales, and has products that range from protein dimers to macroscopic amyloid fibrils. Aberrant aggregation is associated with more than 25 diseases, which include Alzheimer's, Parkinson's, Huntington's, and type II diabetes. Amyloid aggregation has been extensively studied in the test tube, therefore under conditions that are far from physiological relevance. Hence, there is dire need to extend these investigations to in vivo conditions where amyloid formation is affected by a myriad of biochemical interactions. As a hallmark of neurodegenerative diseases, these interactions need to be understood in detail to develop novel therapeutic interventions, as millions of people globally suffer from neurodegenerative disorders and type II diabetes. The aim of this review is to document the progress in the research on amyloid formation from a physicochemical perspective with a special focus on the physiological factors influencing the aggregation of the amyloid-β peptide, the islet amyloid polypeptide, α-synuclein, and the hungingtin protein.
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Affiliation(s)
- Michael C Owen
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 753/5, Brno 625 00, Czech Republic
| | - David Gnutt
- Institute of Physical and Theoretical Chemistry, TU Braunschweig, Rebenring 56, 38106 Braunschweig, Germany and Lead Discovery Wuppertal, Bayer AG, 42096 Wuppertal, Germany
| | - Mimi Gao
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Str. 4a, 44227 Dortmund, Germany and Sanofi-Aventis Deutschland GmbH, R&D, Industriepark Höchst, 65926 Frankfurt, Germany
| | - Sebastian K T S Wärmländer
- Department of Biochemistry and Biophysics, Stockholm University, Svante Arrhenius väg 16C, 106 91 Stockholm, Sweden
| | - Jüri Jarvet
- Department of Biochemistry and Biophysics, Stockholm University, Svante Arrhenius väg 16C, 106 91 Stockholm, Sweden
| | - Astrid Gräslund
- Department of Biochemistry and Biophysics, Stockholm University, Svante Arrhenius väg 16C, 106 91 Stockholm, Sweden
| | - Roland Winter
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Str. 4a, 44227 Dortmund, Germany
| | - Simon Ebbinghaus
- Institute of Physical and Theoretical Chemistry, TU Braunschweig, Rebenring 56, 38106 Braunschweig, Germany
| | - Birgit Strodel
- Institute of Complex Systems: Structural Biochemistry, Forschungszentrum Jülich, 42525 Jülich, Germany. and Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
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11
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Wang Y, Feng X, Shen B, Ma J, Zhao W. Is Vascular Amyloidosis Intertwined with Arterial Aging, Hypertension and Atherosclerosis? Front Genet 2017; 8:126. [PMID: 29085385 PMCID: PMC5649204 DOI: 10.3389/fgene.2017.00126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 09/04/2017] [Indexed: 12/21/2022] Open
Abstract
Vascular amyloidosis (VA) is a component of aging, but both VA and aging move forward together. Although, not all age-related molecules are involved with VA, some molecules are involved in a crosstalk between both of them. However, the cellular mechanism by which, vascular cells are phenotypically shifted to arterial remodeling, is not only involved in aging but also linked to VA. Additionally, patients with hypertension and atherosclerosis are susceptible to VA, while amyloidosis alone may provide fertile soil for the initiation and progression of subsequent hypertension and atherosclerosis. It is known that hypertension, atherosclerosis and amyloidosis can be viewed as accelerated aging. This review summarizes the available experimental and clinical evidence to help the reader to understand the advance and underlying mechanisms for VA involvement in and interaction with aging. Taken together, it is clear that VA, hypertension and atherosclerosis are closely intertwined with arterial aging as equal partners.
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Affiliation(s)
- Yushi Wang
- Cardiovascular Center, The First Hospital of Jilin University, Changchun, China
| | - Xiaoxing Feng
- Cardiovascular Center, The First Hospital of Jilin University, Changchun, China
| | - Botao Shen
- Cardiovascular Center, The First Hospital of Jilin University, Changchun, China
| | - Jing Ma
- Cardiovascular Center, The First Hospital of Jilin University, Changchun, China
| | - Waiou Zhao
- Cardiovascular Center, The First Hospital of Jilin University, Changchun, China
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Jackson MP, Hewitt EW. Why are Functional Amyloids Non-Toxic in Humans? Biomolecules 2017; 7:biom7040071. [PMID: 28937655 PMCID: PMC5745454 DOI: 10.3390/biom7040071] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/18/2017] [Accepted: 09/20/2017] [Indexed: 12/26/2022] Open
Abstract
Amyloids were first identified in association with amyloidoses, human diseases in which proteins and peptides misfold into amyloid fibrils. Subsequent studies have identified an array of functional amyloid fibrils that perform physiological roles in humans. Given the potential for the production of toxic species in amyloid assembly reactions, it is remarkable that cells can produce these functional amyloids without suffering any obvious ill effect. Although the precise mechanisms are unclear, there are a number of ways in which amyloid toxicity may be prevented. These include regulating the level of the amyloidogenic peptides and proteins, minimising the production of prefibrillar oligomers in amyloid assembly reactions, sequestrating amyloids within membrane bound organelles, controlling amyloid assembly by other molecules, and disassembling the fibrils under physiological conditions. Crucially, a better understanding of how toxicity is avoided in the production of functional amyloids may provide insights into the prevention of amyloid toxicity in amyloidoses.
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Affiliation(s)
- Matthew P Jackson
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
| | - Eric W Hewitt
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
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13
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Quittot N, Sebastiao M, Bourgault S. Modulation of amyloid assembly by glycosaminoglycans: from mechanism to biological significance. Biochem Cell Biol 2017; 95:329-337. [DOI: 10.1139/bcb-2016-0236] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Glycosaminoglycans (GAGs) are long and unbranched polysaccharides that are abundant in the extracellular matrix and basement membrane of multicellular organisms. These linear polyanionic macromolecules are involved in many physiological functions from cell adhesion to cellular signaling. Interestingly, amyloid fibrils extracted from patients afflicted with protein misfolding diseases are virtually always associated with GAGs. Amyloid fibrils are highly organized nanostructures that have been historically associated with pathological states, such as Alzheimer’s disease and systemic amyloidoses. However, recent studies have identified functional amyloids that accomplish crucial physiological roles in almost all living organisms, from bacteria to insects and mammals. Over the last 2 decades, numerous reports have revealed that sulfated GAGs accelerate and (or) promote the self-assembly of a large diversity of proteins, both inherently amyloidogenic and non-aggregation prone. Despite the fact that many studies have investigated the molecular mechanism(s) by which GAGs induce amyloid assembly, the mechanistic elucidation of GAG-mediated amyloidogenesis still remains the subject of active research. In this review, we expose the contribution of GAGs in amyloid assembly, and we discuss the pathophysiological and functional significance of GAG-mediated fibrillization. Finally, we propose mechanistic models of the unique and potent ability of sulfated GAGs to hasten amyloid fibril formation.
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Affiliation(s)
- Noé Quittot
- Department of Chemistry, Pharmaqam, C.P. 8888, Succursale Centre-Ville, Université du Québec à Montréal (UQAM), Montreal, QC H3C 3P8, Canada
- Department of Chemistry, Pharmaqam, C.P. 8888, Succursale Centre-Ville, Université du Québec à Montréal (UQAM), Montreal, QC H3C 3P8, Canada
| | - Mathew Sebastiao
- Department of Chemistry, Pharmaqam, C.P. 8888, Succursale Centre-Ville, Université du Québec à Montréal (UQAM), Montreal, QC H3C 3P8, Canada
- Department of Chemistry, Pharmaqam, C.P. 8888, Succursale Centre-Ville, Université du Québec à Montréal (UQAM), Montreal, QC H3C 3P8, Canada
| | - Steve Bourgault
- Department of Chemistry, Pharmaqam, C.P. 8888, Succursale Centre-Ville, Université du Québec à Montréal (UQAM), Montreal, QC H3C 3P8, Canada
- Department of Chemistry, Pharmaqam, C.P. 8888, Succursale Centre-Ville, Université du Québec à Montréal (UQAM), Montreal, QC H3C 3P8, Canada
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14
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Oxidative Stress Alters the Morphology and Toxicity of Aortic Medial Amyloid. Biophys J 2016; 109:2363-70. [PMID: 26636947 PMCID: PMC4675884 DOI: 10.1016/j.bpj.2015.10.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 09/18/2015] [Accepted: 10/13/2015] [Indexed: 11/24/2022] Open
Abstract
The aggregation and fibril deposition of amyloid proteins have been implicated in a range of neurodegenerative and vascular diseases, and yet the underlying molecular mechanisms are poorly understood. Here, we use a combination of cell-based assays, biophysical analysis, and atomic force microscopy to investigate the potential involvement of oxidative stress in aortic medial amyloid (AMA) pathogenesis and deposition. We show that medin, the main constituent of AMA, can induce an environment rich in oxidative species, increasing superoxide and reducing bioavailable nitric oxide in human cells. We investigate the role that this oxidative environment may play in altering the aggregation process of medin and identify potential posttranslational modification sites where site-specific modification and interaction can be unambiguously demonstrated. In an oxidizing environment, medin is nitrated at tyrosine and tryptophan residues, with resultant effects on morphology that lead to longer fibrils with increased toxicity. This provides further motivation to investigate the role of oxidative stress in AMA pathogenicity.
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15
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Davies HA, Madine J, Middleton DA. Comparisons with amyloid-β reveal an aspartate residue that stabilizes fibrils of the aortic amyloid peptide medin. J Biol Chem 2015; 290:7791-803. [PMID: 25614623 PMCID: PMC4367279 DOI: 10.1074/jbc.m114.602177] [Citation(s) in RCA: 12] [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: 08/14/2014] [Revised: 01/19/2015] [Indexed: 11/16/2022] Open
Abstract
Aortic medial amyloid (AMA) is the most common localized human amyloid, occurring in virtually all of the Caucasian population over the age of 50. The main protein component of AMA, medin, readily assembles into amyloid-like fibrils in vitro. Despite the prevalence of AMA, little is known about the self-assembly mechanism of medin or the molecular architecture of the fibrils. The amino acid sequence of medin is strikingly similar to the sequence of the Alzheimer disease (AD) amyloid-β (Aβ) polypeptides around the structural turn region of Aβ, where mutations associated with familial, early onset AD, have been identified. Asp(25) and Lys(30) of medin align with residues Asp(23) and Lys(28) of Aβ, which are known to form a stabilizing salt bridge in some fibril morphologies. Here we show that substituting Asp(25) of medin with asparagine (D25N) impedes assembly into fibrils and stabilizes non-cytotoxic oligomers. Wild-type medin, by contrast, aggregates into β-sheet-rich amyloid-like fibrils within 50 h. A structural analysis of wild-type fibrils by solid-state NMR suggests a molecular repeat unit comprising at least two extended β-strands, separated by a turn stabilized by a Asp(25)-Lys(30) salt bridge. We propose that Asp(25) drives the assembly of medin by stabilizing the fibrillar conformation of the peptide and is thus reminiscent of the influence of Asp(23) on the aggregation of Aβ. Pharmacological comparisons of wild-type medin and D25N will help to ascertain the pathological significance of this poorly understood protein.
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Affiliation(s)
- Hannah A Davies
- From the Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, United Kingdom and
| | - Jillian Madine
- From the Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, United Kingdom and
| | - David A Middleton
- the Department of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
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16
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Iannuzzi C, Irace G, Sirangelo I. The effect of glycosaminoglycans (GAGs) on amyloid aggregation and toxicity. Molecules 2015; 20:2510-28. [PMID: 25648594 PMCID: PMC6272481 DOI: 10.3390/molecules20022510] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 01/29/2015] [Indexed: 01/15/2023] Open
Abstract
Amyloidosis is a protein folding disorder in which normally soluble proteins are deposited extracellularly as insoluble fibrils, impairing tissue structure and function. Charged polyelectrolytes such as glycosaminoglycans (GAGs) are frequently found associated with the proteinaceous deposits in tissues of patients affected by amyloid diseases. Experimental evidence indicate that they can play an active role in favoring amyloid fibril formation and stabilization. Binding of GAGs to amyloid fibrils occurs mainly through electrostatic interactions involving the negative polyelectrolyte charges and positively charged side chains residues of aggregating protein. Similarly to catalyst for reactions, GAGs favor aggregation, nucleation and amyloid fibril formation functioning as a structural templates for the self-assembly of highly cytotoxic oligomeric precursors, rich in β-sheets, into harmless amyloid fibrils. Moreover, the GAGs amyloid promoting activity can be facilitated through specific interactions via consensus binding sites between amyloid polypeptide and GAGs molecules. We review the effect of GAGs on amyloid deposition as well as proteins not strictly related to diseases. In addition, we consider the potential of the GAGs therapy in amyloidosis.
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Affiliation(s)
- Clara Iannuzzi
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Università di Napoli, Via L. De Crecchio 7, Napoli 80138, Italy.
| | - Gaetano Irace
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Università di Napoli, Via L. De Crecchio 7, Napoli 80138, Italy.
| | - Ivana Sirangelo
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Università di Napoli, Via L. De Crecchio 7, Napoli 80138, Italy.
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17
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Madine J, Davies HA, Hughes E, Middleton DA. Heparin promotes the rapid fibrillization of a peptide with low intrinsic amyloidogenicity. Biochemistry 2013; 52:8984-92. [PMID: 24279288 DOI: 10.1021/bi401231u] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amyloid deposits in vivo are complex mixtures composed of protein fibrils and nonfibrillar components, including polysaccharides of the glycosaminoglycan (GAG) class. It has been widely documented that GAGs influence the initiation and progress of self-assembly by several disease-associated amyloidogenic proteins and peptides in vitro. Here we investigated whether the GAG heparin can serve as a cofactor to induce amyloid-like fibril formation in a peptide predicted to have a weak propensity to aggregate and not associated with amyloid disorders. We selected the 23-residue peptide PLB(1-23), which corresponds to the acetylated cytoplasmic domain of the phospholamban transmembrane protein. PLB(1-23) remains unfolded in aqueous solution for >24 h and does not bind thioflavin T over this time period, in agreement with computer predictions that the peptide has a very low intrinsic amyloidogenicity. In the presence of low-molecular mass (5 kDa) heparin, which binds PLB(1-23) with micromolar affinity, the peptide undergoes spontaneous and rapid assembly into amyloid-like fibrils, the effect being more pronounced at pH 5.5 than at pH 7.4. At the lower pH, peptide aggregation is accompanied by a transition to a β-sheet rich structure. These results are consistent with the polyanionic heparin serving as a scaffold to enhance aggregation by aligning the peptide molecules in the correct orientation and with the appropriate periodicity. PLB(1-23) is toxic to cells when added in isolation, and promotion of fibril formation by heparin can reduce the toxicity of this peptide, consistent with the notion that amyloid-like fibrils represent a benign end stage of fibrillization. This work provides insight into the role that heparin and other glycosaminoglycans may play in amyloid formation and provides therapeutic avenues targeting the reduction of cytotoxicity of species along the amyloid formation pathway.
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Affiliation(s)
- Jillian Madine
- Institute of Integrative Biology, University of Liverpool , Crown Street, Liverpool L69 7ZB, United Kingdom
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18
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De Carufel CA, Nguyen PT, Sahnouni S, Bourgault S. New insights into the roles of sulfated glycosaminoglycans in islet amyloid polypeptide amyloidogenesis and cytotoxicity. Biopolymers 2013; 100:645-55. [DOI: 10.1002/bip.22243] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 03/11/2013] [Accepted: 03/17/2013] [Indexed: 01/16/2023]
Affiliation(s)
| | - Phuong Trang Nguyen
- Department of Chemistry; University of Québec in Montreal; Montreal QC H3C 3P8 Canada
| | - Sabrina Sahnouni
- Department of Chemistry; University of Québec in Montreal; Montreal QC H3C 3P8 Canada
| | - Steve Bourgault
- Department of Chemistry; University of Québec in Montreal; Montreal QC H3C 3P8 Canada
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19
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Bleiholder C, Do TD, Wu C, Economou NJ, Bernstein SS, Buratto SK, Shea JE, Bowers MT. Ion mobility spectrometry reveals the mechanism of amyloid formation of Aβ(25-35) and its modulation by inhibitors at the molecular level: epigallocatechin gallate and scyllo-inositol. J Am Chem Soc 2013; 135:16926-37. [PMID: 24131107 DOI: 10.1021/ja406197f] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Amyloid cascades leading to peptide β-sheet fibrils and plaques are central to many important diseases. Recently, intermediate assemblies of these cascades were identified as the toxic agents that interact with the cellular machinery. The relationship between the transformation from natively unstructured assembly to the β-sheet oligomers to disease is important in understanding disease onset and the development of therapeutic agents. Research on this early oligomeric region has largely been unsuccessful since traditional techniques measure only ensemble average oligomer properties. Here, ion mobility methods are utilized to deduce the modulation of peptide self-assembly pathways in the amyloid-β protein fragment Aβ(25-35) by two amyloid inhibitors (epigallocatechin gallate and scyllo-inositol) that are currently in clinical trials for Alzheimer's Disease. We provide evidence that suppression of β-extended oligomers from the onset of the conversion into β-oligomer conformations is essential for effective attenuation of β-structured amyloid oligomeric species often associated with oligomer toxicity. Furthermore, we demonstrate the ease with which ion mobility spectrometry-mass spectrometry can guide the development of therapeutic agents and drug evaluation by providing molecular level insight into the amyloid formation process and its modulation by small molecule assembly modulators.
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Affiliation(s)
- Christian Bleiholder
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106-9510, United States
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20
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Westermark GT, Westermark P. Localized amyloids important in diseases outside the brain - lessons from the islets of Langerhans and the thoracic aorta. FEBS J 2011; 278:3918-29. [DOI: 10.1111/j.1742-4658.2011.08298.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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21
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Heparin induces harmless fibril formation in amyloidogenic W7FW14F apomyoglobin and amyloid aggregation in wild-type protein in vitro. PLoS One 2011; 6:e22076. [PMID: 21779376 PMCID: PMC3135624 DOI: 10.1371/journal.pone.0022076] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 06/14/2011] [Indexed: 12/02/2022] Open
Abstract
Glycosaminoglycans (GAGs) are frequently associated with amyloid deposits in most amyloid diseases, and there is evidence to support their active role in amyloid fibril formation. The purpose of this study was to obtain structural insight into GAG-protein interactions and to better elucidate the molecular mechanism underlying the effect of GAGs on the amyloid aggregation process and on the related cytotoxicity. To this aim, using Fourier transform infrared and circular diochroism spectroscopy, electron microscopy and thioflavin fluorescence dye we examined the effect of heparin and other GAGs on the fibrillogenesis and cytotoxicity of aggregates formed by the amyloidogenic W7FW14 apomyoglobin mutant. Although this protein is unrelated to human disease, it is a suitable model for in vitro studies because it forms amyloid-like fibrils under physiological conditions of pH and temperature. Heparin strongly stimulated aggregation into amyloid fibrils, thereby abolishing the lag-phase normally detected following the kinetics of the process, and increasing the yield of fibrils. Moreover, the protein aggregates were harmless when assayed for cytotoxicity in vitro. Neutral or positive compounds did not affect the aggregation rate, and the early aggregates were highly cytotoxic. The surprising result that heparin induced amyloid fibril formation in wild-type apomyoglobin and in the partially folded intermediate state of the mutant, i.e., proteins that normally do not show any tendency to aggregate, suggested that the interaction of heparin with apomyoglobin is highly specific because of the presence, in protein turn regions, of consensus sequences consisting of alternating basic and non-basic residues that are capable of binding heparin molecules. Our data suggest that GAGs play a dual role in amyloidosis, namely, they promote beneficial fibril formation, but they also function as pathological chaperones by inducing amyloid aggregation.
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Jha S, Patil SM, Gibson J, Nelson CE, Alder NN, Alexandrescu AT. Mechanism of amylin fibrillization enhancement by heparin. J Biol Chem 2011; 286:22894-904. [PMID: 21555785 DOI: 10.1074/jbc.m110.215814] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We characterized the interaction of amylin with heparin fragments of defined length, which model the glycosaminoglycan chains associated with amyloid deposits found in type 2 diabetes. Binding of heparin fragments to the positively charged N-terminal half of monomeric amylin depends on the concentration of negatively charged saccharides but is independent of oligosaccharide length. By contrast, amylin fibrillogenesis has a sigmoidal dependence on heparin fragment length, with an enhancement observed for oligosaccharides longer than four monomers and a leveling off of effects beyond 12 monomers. The length dependence suggests that the negatively charged helical structure of heparin electrostatically complements the positively charged surface of the fibrillar amylin cross-β structure. Fluorescence resonance energy transfer and total internal reflection fluorescence microscopy experiments indicate that heparin associates with amylin fibrils, rather than enhancing fibrillogenesis catalytically. Short heparin fragments containing two- or eight-saccharide monomers protect against amylin cytotoxicity toward a MIN6 mouse cell model of pancreatic β-cells.
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Affiliation(s)
- Suman Jha
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269-3125, USA
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