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Wang B, Lin X, Zhou J, Xie C, Li C, Dong R, Zhang G, Sun X, Wang M, Bi Y. Insulin-like growth factor-1 improves postoperative cognitive dysfunction following splenectomy in aged rats. Exp Ther Med 2021; 21:215. [PMID: 33574912 PMCID: PMC7818527 DOI: 10.3892/etm.2021.9647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 09/29/2020] [Indexed: 11/15/2022] Open
Abstract
Postoperative cognitive dysfunction (POCD) is a serious complication following anesthesia and operations in aged patients undergoing surgical intervention. It is characterized by temporary or permanent cognitive decline, memory impairment and deterioration in language comprehension and social adaption ability. Therefore, the development of POCD prevention and treatment tools has become an area of interest. The current study assessed the therapeutic effects of insulin-like growth factor-1 (IGF-1) on POCD in aged rats and explored the underlying mechanisms. Model rats underwent splenectomy under 1.5-2% isoflurane and mechanical ventilation. IGF-1 (50 µg/kg) was diluted in normal saline and administered by abdominal hypodermic injection daily from the operation to day 7 post-operation. Following splenectomy, the animals showed marked cognitive impairment as determined by the Morris water maze test. Hippocampal protein levels of amyloid precursor protein (APP), β-site APP-cleaving enzyme-1 (BACE-1), amyloid-β (Aβ), capase3, Bax and Bcl-2 were assessed by immunoblotting. Neuronal apoptosis in the hippocampus was analyzed using a TUNEL assay. The results demonstrated that the levels of APP, BACE-1, Aβ, caspase3 and Bax were increased following splenectomy, while the levels of Bcl2 were reduced at days 1, 3 and 7 post-operation in aged rats. However, IGF-1 downregulated APP, BACE-1, Aβ, capase3 and Bax, and upregulated Bcl2 at these time points following splenectomy. TUNEL staining revealed that administration of IGF-1 significantly reduced neuronal apoptosis in the hippocampal CA1 region following splenectomy. These results indicated that IGF-1 decreased Aβ-protein production and inhibited neuronal apoptosis in the hippocampus following splenectomy, subsequently alleviating POCD.
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Affiliation(s)
- Bin Wang
- Department of Anesthesiology, Qingdao Municipal Hospital Affiliated to Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Xu Lin
- Department of Anesthesiology, Qingdao Municipal Hospital Affiliated to Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Jiahui Zhou
- Department of Anesthesiology, Qingdao Municipal Hospital Affiliated to Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Chunhui Xie
- Department of Anesthesiology, Weifang Medical University, Weifang, Shandong 261042, P.R. China
| | - Chuan Li
- Department of Anesthesiology, Weifang Medical University, Weifang, Shandong 261042, P.R. China
| | - Rui Dong
- Department of Anesthesiology, Qingdao Municipal Hospital Affiliated to Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Gaofeng Zhang
- Department of Anesthesiology, Qingdao Municipal Hospital Affiliated to Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Xiaopeng Sun
- Department of Anesthesiology, Qingdao Municipal Hospital Affiliated to Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Mingshan Wang
- Department of Anesthesiology, Qingdao Municipal Hospital Affiliated to Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Yanlin Bi
- Department of Anesthesiology, Qingdao Municipal Hospital Affiliated to Qingdao University, Qingdao, Shandong 266071, P.R. China
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Ahmed T, Zahid S, Mahboob A, Farhat SM. Cholinergic System and Post-translational Modifications: An Insight on the Role in Alzheimer's Disease. Curr Neuropharmacol 2017; 15:480-494. [PMID: 27012953 PMCID: PMC5543671 DOI: 10.2174/1570159x14666160325121145] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 12/02/2015] [Accepted: 03/03/2016] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Alzheimer's disease (AD) is the most common form of old age dementia. The formation of amyloid plaques (Aβ), neurofibrillary tangles and loss of basal forebrain cholinergic neurons are the hallmark events in the pathology of AD. LITERATURE REVIEW Cholinergic system is one of the most important neurotransmitter system involved in learning and memory which preferentially degenerates in the initial stages of AD. Activation of cholinergic receptors (muscarinic and nicotinic) activates multiple pathways which result in post translational modifications (PTMs) in multiple proteins which bring changes in nervous system. Cholinergic receptors-mediated PTMs "in-part" substantially affect the biosynthesis, proteolysis, degradation and expression of many proteins and in particular, amyloid precursor protein (APP). APP is subjected to several PTMs (proteolytic processing, glycosylation, sulfation, and phosphorylation) during its course of processing, resulting in Aβ deposition, leading to AD. Aβ also alters the PTMs of tau which is a microtubule associated protein. Therefore, post-translationally modified tau and Aβ collectively aggravate the neuronal loss that leads to cholinergic hypofunction. CONCLUSION Despite the accumulating evidences, the interaction between cholinergic neurotransmission and the physiological significance of PTM events remain speculative and still needs further exploration. This review focuses on the role of cholinergic system and discusses the significance of PTMs in pathological progression of AD and highlights some important future directions.
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Affiliation(s)
- Touqeer Ahmed
- Neurobiology Laboratory, Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Sector H-12, Islamabad, 44000, Pakistan
| | - Saadia Zahid
- Neurobiology Laboratory, Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Sector H-12, Islamabad, 44000, Pakistan
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Montanari S, Bartolini M, Neviani P, Belluti F, Gobbi S, Pruccoli L, Tarozzi A, Falchi F, Andrisano V, Miszta P, Cavalli A, Filipek S, Bisi A, Rampa A. Multitarget Strategy to Address Alzheimer's Disease: Design, Synthesis, Biological Evaluation, and Computational Studies of Coumarin-Based Derivatives. ChemMedChem 2015; 11:1296-308. [DOI: 10.1002/cmdc.201500392] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Indexed: 12/30/2022]
Affiliation(s)
- Serena Montanari
- Department of Pharmacy & Biotechnology, Alma Mater Studiorum; University of Bologna; Via Belmeloro 6 40126 Bologna Italy
| | - Manuela Bartolini
- Department of Pharmacy & Biotechnology, Alma Mater Studiorum; University of Bologna; Via Belmeloro 6 40126 Bologna Italy
| | - Paolo Neviani
- Department for Life Quality Studies, Alma Mater Studiorum; University of Bologna; Corso d'Augusto 237 47921 Rimini Italy
| | - Federica Belluti
- Department of Pharmacy & Biotechnology, Alma Mater Studiorum; University of Bologna; Via Belmeloro 6 40126 Bologna Italy
| | - Silvia Gobbi
- Department of Pharmacy & Biotechnology, Alma Mater Studiorum; University of Bologna; Via Belmeloro 6 40126 Bologna Italy
| | - Letizia Pruccoli
- Department for Life Quality Studies, Alma Mater Studiorum; University of Bologna; Corso d'Augusto 237 47921 Rimini Italy
| | - Andrea Tarozzi
- Department for Life Quality Studies, Alma Mater Studiorum; University of Bologna; Corso d'Augusto 237 47921 Rimini Italy
| | - Federico Falchi
- CompuNet; Italian Institute of Technology; via Morego 30 16163 Genova Italy
| | - Vincenza Andrisano
- Department for Life Quality Studies, Alma Mater Studiorum; University of Bologna; Corso d'Augusto 237 47921 Rimini Italy
| | - Przemysław Miszta
- Faculty of Chemistry; Biological & Chemical Research Centre; University of Warsaw; Pasteura 1 02093 Warsaw Poland
| | - Andrea Cavalli
- Department of Pharmacy & Biotechnology, Alma Mater Studiorum; University of Bologna; Via Belmeloro 6 40126 Bologna Italy
- CompuNet; Italian Institute of Technology; via Morego 30 16163 Genova Italy
| | - Sławomir Filipek
- Faculty of Chemistry; Biological & Chemical Research Centre; University of Warsaw; Pasteura 1 02093 Warsaw Poland
| | - Alessandra Bisi
- Department of Pharmacy & Biotechnology, Alma Mater Studiorum; University of Bologna; Via Belmeloro 6 40126 Bologna Italy
| | - Angela Rampa
- Department of Pharmacy & Biotechnology, Alma Mater Studiorum; University of Bologna; Via Belmeloro 6 40126 Bologna Italy
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4
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Paramelle D, Nieves D, Brun B, Kraut RS, Fernig DG. Targeting Cell Membrane Lipid Rafts by Stoichiometric Functionalization of Gold Nanoparticles With a Sphingolipid-Binding Domain Peptide. Adv Healthc Mater 2015; 4:911-7. [PMID: 25650337 DOI: 10.1002/adhm.201400730] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 01/14/2015] [Indexed: 01/15/2023]
Abstract
A non-membrane protein-based nanoparticle agent for the tracking of lipid rafts on live cells is produced by stoichiometric functionalization of gold nanoparticles with a previously characterized sphingolipid- and cell membrane microdomain-binding domain peptide (SBD). The SBD peptide is inserted in a self-assembled monolayer of peptidol and alkane thiol ethylene glycol, on gold nanoparticles surface. The stoichiometric functionalization of nanoparticles with the SBD peptide, essential for single molecule tracking, is achieved by means of non-affinity nanoparticle purification. The SBD-nanoparticles have remarkable long-term resistance to electrolyte-induced aggregation and ligand-exchange and have no detectable non-specific binding to live cells. Binding and diffusion of SBD-nanoparticles bound to the membrane of live cells is measured by real-time photothermal microscopy and shows the dynamics of sphingolipid-enriched microdomains on cells membrane, with evidence for clustering, splitting, and diffusion over time of the SBD-nanoparticle labeled membrane domains. The monofunctionalized SBD-nanoparticle is a promising targeting agent for the tracking of lipid rafts independently of their protein composition and the labelling requires no prior modification of the cells. This approach has potential for further functionalization of the particles to manipulate the organization of, or targeting to microdomains that control signaling events and thereby lead to novel diagnostics and therapeutics.
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Affiliation(s)
- David Paramelle
- Institute of Materials Research and Engineering; A*STAR (Agency for Science Technology and Research); 3 Research Link 117602 Singapore
| | - Daniel Nieves
- Department of Biochemistry; Institute of Integrative Biology; University of Liverpool; Liverpool L69 7ZB UK
| | - Benjamin Brun
- Institute of Materials Research and Engineering; A*STAR (Agency for Science Technology and Research); 3 Research Link 117602 Singapore
| | - Rachel S. Kraut
- School of Biological Sciences; Nanyang Technological University; 50 Nanyang Ave 639798 Singapore
| | - David G. Fernig
- Department of Biochemistry; Institute of Integrative Biology; University of Liverpool; Liverpool L69 7ZB UK
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Crespi GAN, Hermans SJ, Parker MW, Miles LA. Molecular basis for mid-region amyloid-β capture by leading Alzheimer's disease immunotherapies. Sci Rep 2015; 5:9649. [PMID: 25880481 PMCID: PMC4549621 DOI: 10.1038/srep09649] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 03/12/2015] [Indexed: 12/24/2022] Open
Abstract
Solanezumab (Eli Lilly) and crenezumab (Genentech) are the leading clinical antibodies targeting Amyloid-β (Aβ) to be tested in multiple Phase III clinical trials for the prevention of Alzheimer's disease in at-risk individuals. Aβ capture by these clinical antibodies is explained here with the first reported mid-region Aβ-anti-Aβ complex crystal structure. Solanezumab accommodates a large Aβ epitope (960 Å(2) buried interface over residues 16 to 26) that forms extensive contacts and hydrogen bonds to the antibody, largely via main-chain Aβ atoms and a deeply buried Phe19-Phe20 dipeptide core. The conformation of Aβ captured is an intermediate between observed sheet and helical forms with intramolecular hydrogen bonds stabilising residues 20-26 in a helical conformation. Remarkably, Aβ-binding residues are almost perfectly conserved in crenezumab. The structure explains the observed shared cross reactivity of solanezumab and crenezumab with proteins abundant in plasma that exhibit this Phe-Phe dipeptide.
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MESH Headings
- Alzheimer Disease/therapy
- Amyloid beta-Peptides/chemistry
- Amyloid beta-Peptides/immunology
- Amyloid beta-Peptides/metabolism
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/therapeutic use
- Antibodies, Monoclonal, Humanized/chemistry
- Antibodies, Monoclonal, Humanized/immunology
- Antibodies, Monoclonal, Humanized/therapeutic use
- Binding Sites
- Crystallography, X-Ray
- Dipeptides/blood
- Dipeptides/immunology
- Humans
- Hydrogen Bonding
- Immunotherapy
- Molecular Dynamics Simulation
- Protein Structure, Tertiary
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Affiliation(s)
- Gabriela A. N. Crespi
- ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
| | - Stefan J. Hermans
- ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
| | - Michael W. Parker
- ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Luke A. Miles
- ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
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6
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Alzheimer's disease--a panorama glimpse. Int J Mol Sci 2014; 15:12631-50. [PMID: 25032844 PMCID: PMC4139864 DOI: 10.3390/ijms150712631] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 06/26/2014] [Accepted: 07/10/2014] [Indexed: 01/05/2023] Open
Abstract
The single-mutation of genes associated with Alzheimer's disease (AD) increases the production of Aβ peptides. An elevated concentration of Aβ peptides is prone to aggregation into oligomers and further deposition as plaque. Aβ plaques and neurofibrillary tangles are two hallmarks of AD. In this review, we provide a broad overview of the diverses sources that could lead to AD, which include genetic origins, Aβ peptides and tau protein. We shall discuss on tau protein and tau accumulation, which result in neurofibrillary tangles. We detail the mechanisms of Aβ aggregation, fibril formation and its polymorphism. We then show the possible links between Aβ and tau pathology. Furthermore, we summarize the structural data of Aβ and its precursor protein obtained via Nuclear Magnetic Resonance (NMR) or X-ray crystallography. At the end, we go through the C-terminal and N-terminal truncated Aβ variants. We wish to draw reader's attention to two predominant and toxic Aβ species, namely Aβ4-42 and pyroglutamate amyloid-beta peptides, which have been neglected for more than a decade and may be crucial in Aβ pathogenesis due to their dominant presence in the AD brain.
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7
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Lin Y, Lee YH, Yoshimura Y, Yagi H, Goto Y. Solubility and supersaturation-dependent protein misfolding revealed by ultrasonication. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:1845-1854. [PMID: 24059752 DOI: 10.1021/la403100h] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Although alcohols are useful cosolvents for producing amyloid fibrils, the underlying mechanism of alcohol-dependent fibrillation is unclear. We studied the alcohol-induced fibrillation of hen egg-white lysozyme at various concentrations of ethanol, 2,2,2-trifluoroethanol (TFE), and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). Under the conditions where the alcohol-denatured lysozyme retained metastability, ultrasonication effectively triggered fibrillation. The optimal alcohol concentration depended on the alcohol species. HFIP showed a sharp maximum at 12-16%. For TFE, a broad maximum at 40-80% was observed. Ethanol exhibited only an increase in fibrillation above 60%. These profiles were opposite to the equilibrium solubility of lysozyme in water/alcohol mixtures. The results indicate that although fibrillation is determined by solubility, supersaturation prevents conformational transitions and ultrasonication is highly effective in minimizing an effect of supersaturation. We propose an alcohol-dependent protein misfolding funnel useful for examining amyloidogenicity. This misfolding funnel will apply to fibrillation under physiological conditions where biological environments play important roles in decreasing the solubility.
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Affiliation(s)
- Yuxi Lin
- Institute for Protein Research, Osaka University , 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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8
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Okamoto A, Nomura K, Yano A, Higai S, Kondo T, Kamba S, Kurita N. Proposal for an inhibitor of Alzheimer's disease blocking aggregation of amyloid-β peptides:ab initiomolecular simulations. ACTA ACUST UNITED AC 2013. [DOI: 10.1088/1742-6596/433/1/012033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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9
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Lauterbach T, Manna M, Ruhnow M, Wisantoso Y, Wang Y, Matysik A, Oglęcka K, Mu Y, Geifman-Shochat S, Wohland T, Kraut R. Weak glycolipid binding of a microdomain-tracer peptide correlates with aggregation and slow diffusion on cell membranes. PLoS One 2012; 7:e51222. [PMID: 23251459 PMCID: PMC3520979 DOI: 10.1371/journal.pone.0051222] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 10/30/2012] [Indexed: 11/18/2022] Open
Abstract
Organized assembly or aggregation of sphingolipid-binding ligands, such as certain toxins and pathogens, has been suggested to increase binding affinity of the ligand to the cell membrane and cause membrane reorganization or distortion. Here we show that the diffusion behavior of the fluorescently tagged sphingolipid-interacting peptide probe SBD (Sphingolipid Binding Domain) is altered by modifications in the construction of the peptide sequence that both result in a reduction in binding to ganglioside-containing supported lipid membranes, and at the same time increase aggregation on the cell plasma membrane, but that do not change relative amounts of secondary structural features. We tested the effects of modifying the overall charge and construction of the SBD probe on its binding and diffusion behavior, by Surface Plasmon Resonance (SPR; Biacore) analysis on lipid surfaces, and by Fluorescence Correlation Spectroscopy (FCS) on live cells, respectively. SBD binds preferentially to membranes containing the highly sialylated gangliosides GT1b and GD1a. However, simple charge interactions of the peptide with the negative ganglioside do not appear to be a critical determinant of binding. Rather, an aggregation-suppressing amino acid composition and linker between the fluorophore and the peptide are required for optimum binding of the SBD to ganglioside-containing supported lipid bilayer surfaces, as well as for interaction with the membrane. Interestingly, the strength of interactions with ganglioside-containing artificial membranes is mirrored in the diffusion behavior by FCS on cell membranes, with stronger binders displaying similar characteristic diffusion profiles. Our findings indicate that for aggregation-prone peptides, aggregation occurs upon contact with the cell membrane, and rather than giving a stronger interaction with the membrane, aggregation is accompanied by weaker binding and complex diffusion profiles indicative of heterogeneous diffusion behavior in the probe population.
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Affiliation(s)
- Tim Lauterbach
- School of Biological Sciences, Nanyang Technological University, Singapore
- Institut für Lebensmittel- und Bioverfahrenstechnik, Technische Universität Dresden, Dresden, Germany
| | - Manoj Manna
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Maria Ruhnow
- School of Biological Sciences, Nanyang Technological University, Singapore
- Institut für Lebensmittel- und Bioverfahrenstechnik, Technische Universität Dresden, Dresden, Germany
| | - Yudi Wisantoso
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Yaofeng Wang
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Artur Matysik
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Kamila Oglęcka
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Yuguang Mu
- School of Biological Sciences, Nanyang Technological University, Singapore
| | | | - Thorsten Wohland
- Department of Chemistry, National University of Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore
- Centre for Bioimaging Sciences, National University of Singapore, Singapore
| | - Rachel Kraut
- School of Biological Sciences, Nanyang Technological University, Singapore
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10
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Maltsev AV, Bystryak S, Galzitskaya OV. The role of β-amyloid peptide in neurodegenerative diseases. Ageing Res Rev 2011; 10:440-52. [PMID: 21406255 DOI: 10.1016/j.arr.2011.03.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 03/03/2011] [Accepted: 03/07/2011] [Indexed: 12/27/2022]
Abstract
Studies of neurodegenerative disorders (NDDs) are drawing more attention of researchers worldwide due to the high incidence of Alzheimer's disease (AD). The pathophysiology of such disorders is, in part, characterized by the transition of a wild-type peptide from its native conformation into a very stable pathological isoform. Subsequently, these abnormal proteins form aggregates of amyloid fibrils that continuously increase in size. Changes in the metabolic processes of neurons (e.g. oxidative stress, hyperphosphorylation of the tau protein, and resulting secondary changes in the cell metabolism) ultimately lead to cell death. We hypothesize that extracellular deposition of β-amyloid peptide fibrils and neurofibrillary tangles represents the body's adaptation mechanism, aimed at preservation of autonomic functioning; while the cognitive decline is severe, the rest of the organ systems remain unaffected and continue to function. This hypothesis is supported by the fact that destruction of pathological plaques, fibrils, and tangles and the use of vaccines targeting β-amyloid result in undesirable side effects. To gain a better understanding of the pathophysiology of Alzheimer's disease and to develop novel therapies, continued studies of the sporadic form of disease and the mechanisms triggering conformational changes in β-amyloid peptide fragments are essential. This review is focused on studies investigating the formation of amyloid fibrils and their role in the pathogenesis of neurodegenerative diseases. In addition, we discuss a related disorder--amyloidosis--where formation of fibrils, tangles, and plaques leads to neuronal death which may occur as a result of a failed adaptation process. Further in-depth investigation and comprehensive analysis of alterations in the metabolism of APP, β-amyloid, and tau protein, which have a pathological effect on cell membrane, alter phosphate exchange, and impair other key metabolic functions of the cell long before the characteristic amyloid deposition takes place, is warranted. A better understanding of intraneuronal processes is crucial in identifying specific inhibitors of pathologic neuronal processes and, consequently, will allow for targeted therapy, thus maximizing efficacy of selected therapeutic regimens.
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Affiliation(s)
- A V Maltsev
- Russian Gerontological Research Clinical Center, Russian Ministry of Health Care, Moscow, Russia.
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11
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Micelle-like architecture of the monomer ensemble of Alzheimer's amyloid-β peptide in aqueous solution and its implications for Aβ aggregation. J Mol Biol 2010; 403:148-165. [PMID: 20709081 DOI: 10.1016/j.jmb.2010.08.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 07/27/2010] [Accepted: 08/02/2010] [Indexed: 01/05/2023]
Abstract
Aggregation of amyloid-β (Aβ) peptide, a 39- to 43-residue fragment of the amyloid precursor protein, is associated with Alzheimer's disease, the most common form of dementia in the elderly population. Several experimental studies have tried to characterize the atomic details of amyloid fibrils, which are the final product of Aβ aggregation. Much less is known about species forming during the early stages of aggregation, in particular about the monomeric state of the Aβ peptide that may be viewed as the product of the very first step in the hypothesized amyloid cascade. Here, the equilibrium ensembles of monomeric Aβ alloforms Aβ(1-40) and Aβ(1-42) are investigated by Monte Carlo simulations using an atomistic force field and implicit solvent model that have been shown previously to correctly reproduce the ensemble properties of other intrinsically disordered polypeptides. Our simulation results indicate that at physiological temperatures, both alloforms of Aβ assume a largely collapsed globular structure. Conformations feature a fluid hydrophobic core formed, on average, by contacts both within and between the two segments comprising residues 12-21 and 24-40/42, respectively. Furthermore, the 11 N-terminal residues are completely unstructured, and all charged side chains, in particular those of Glu22 and Asp23, remain exposed to solvent. Taken together, these observations indicate a micelle-like† architecture at the monomer level whose implications for oligomerization, as well as fibril formation and elongation, are discussed. We establish quantitatively the intrinsic disorder of Aβ and find the propensity to form regular secondary structure to be low but sequence specific. In the presence of a global and unspecific bias for backbone conformations to populate the β-basin, the β-sheet propensity along the sequence is consistent with the arrangement of the monomer within the fibril, as derived from solid-state NMR data. These observations indicate that the primary sequence partially encodes fibril structure, but that fibril elongation must be thought of as a templated assembly step.
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12
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Ravault S, Flore C, Saurel O, Milon A, Brasseur R, Lins L. Study of the specific lipid binding properties of Abeta 11-22 fragment at endosomal pH. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:10948-10953. [PMID: 19735146 DOI: 10.1021/la901544g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Increasing evidence implicates interactions between Abeta peptide and lipids in the development of Alzheimer's disease. More generally, Abeta peptide interactions with membranes seem to depend on the composition of the lipid bilayer and the structural features of the peptide. One key parameter should be pH, since one site of intracellular Abeta peptide production and/or accumulation is likely to be endosomes. This intracellular endosomal accumulation was suggested to contribute to disease progression. In this paper, we report a study on the 11-22 amphiphilic domain of Abeta in interaction with model membrane; this region contains most of the charged residues of the N-terminal domain of Abeta. We show that the peptide charge, and more precisely the protonation state of histidines 13 and/or 14, is important for the interaction with lipids. Hence, it is only at endosomal pH that a conformational change of the peptide is observed in the presence of negatively charged lipid vesicles, that is, when both lipid headgroups and histidines can interact through electrostatic interactions. Specific interactions of the fragment with phosphatidylserine and to a lesser extent with phosphatidylcholine, but not phosphatidylethanolamine, are further evidenced by the Langmuir monolayer technique. From our results, we suggest that the protonation state of His residues could have a role in the pathogenic surface interaction of the whole Abeta peptide with membranes.
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Affiliation(s)
- S Ravault
- Centre de Biophysique Moléculaire Numérique, Agricultural University of Gembloux, 5030 Gembloux, Belgium
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13
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Beel AJ, Mobley CK, Kim HJ, Tian F, Hadziselimovic A, Jap B, Prestegard JH, Sanders CR. Structural studies of the transmembrane C-terminal domain of the amyloid precursor protein (APP): does APP function as a cholesterol sensor? Biochemistry 2008; 47:9428-46. [PMID: 18702528 DOI: 10.1021/bi800993c] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The amyloid precursor protein (APP) is subject to alternative pathways of proteolytic processing, leading either to production of the amyloid-beta (Abeta) peptides or to non-amyloidogenic fragments. Here, we report the first structural study of C99, the 99-residue transmembrane C-terminal domain of APP liberated by beta-secretase cleavage. We also show that cholesterol, an agent that promotes the amyloidogenic pathway, specifically binds to this protein. C99 was purified into model membranes where it was observed to homodimerize. NMR data show that the transmembrane domain of C99 is an alpha-helix that is flanked on both sides by mostly disordered extramembrane domains, with two exceptions. First, there is a short extracellular surface-associated helix located just after the site of alpha-secretase cleavage that helps to organize the connecting loop to the transmembrane domain, which is known to be essential for Abeta production. Second, there is a surface-associated helix located at the cytosolic C-terminus, adjacent to the YENPTY motif that plays critical roles in APP trafficking and protein-protein interactions. Cholesterol was seen to participate in saturable interactions with C99 that are centered at the critical loop connecting the extracellular helix to the transmembrane domain. Binding of cholesterol to C99 and, most likely, to APP may be critical for the trafficking of these proteins to cholesterol-rich membrane domains, which leads to cleavage by beta- and gamma-secretase and resulting amyloid-beta production. It is proposed that APP may serve as a cellular cholesterol sensor that is linked to mechanisms for suppressing cellular cholesterol uptake.
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Affiliation(s)
- Andrew J Beel
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232-8725, USA
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Rodziewicz-Motowidło S, Czaplewska P, Sikorska E, Spodzieja M, Kołodziejczyk AS. The Arctic mutation alters helix length and type in the 11-28 beta-amyloid peptide monomer-CD, NMR and MD studies in an SDS micelle. J Struct Biol 2008; 164:199-209. [PMID: 18765285 DOI: 10.1016/j.jsb.2008.07.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 07/11/2008] [Accepted: 07/29/2008] [Indexed: 11/30/2022]
Abstract
The beta-amyloid (Abeta) is the major peptide constituent of neuritic plaques in Alzheimer's disease, and its aggregation is believed to play a central role in the pathogenesis of the disease. Naturally occurring mutations resulting in changes in the Abeta sequence (pos. 21-23) are associated with familial Alzheimer's-like diseases with extensive cerebrovascular pathology. It has been demonstrated that such mutations alter the aggregation ability of Abeta and its neurotoxicity. Among the five mutations at positions 21-23 there is one with distinct clinical characteristics and a potentially distinct pathogenic mechanism-the Arctic (E22G) mutation. We have examined the structures of fragment 11-28 of the native peptide and its E22G variant. This fragment was chosen because it has been shown to be a good model for conformational and aggregation studies as it contains the hydrophobic core responsible for aggregation and the residues critical to alpha-secretase cleavage of APP. The detailed structure of the two peptides was determined using CD, 2D NMR and molecular dynamics techniques under water-SDS micelle conditions. Our studies indicated the existence of partially alpha- and 3(10)-helical conformations in the native and mutated peptide, respectively.
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15
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Valerio M, Porcelli F, Zbilut JP, Giuliani A, Manetti C, Conti F. pH effects on the conformational preferences of amyloid beta-peptide (1-40) in HFIP aqueous solution by NMR spectroscopy. ChemMedChem 2008; 3:833-43. [PMID: 18228239 DOI: 10.1002/cmdc.200700324] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The structure and aggregation state of amyloid beta-peptide (Abeta) in membrane-like environments are important determinants of pathological events in Alzheimer's disease. In fact, the neurotoxic nature of amyloid-forming peptides and proteins is associated with specific conformational transitions proximal to the membrane. Under certain conditions, the Abeta peptide undergoes a conformational change that brings the peptide in solution to a "competent state" for aggregation. Conversion can be obtained at medium pH (5.0-6.0), and in vivo this appears to take place in the endocytic pathway. The combined use of (1)H NMR spectroscopy and molecular dynamics-simulated annealing calculations in aqueous hexafluoroisopropanol simulating the membrane environment, at different pH conditions, enabled us to get some insights into the aggregation process of Abeta, confirming our previous hypotheses of a relationship between conformational flexibility and aggregation propensity. The conformational space of the peptide was explored by means of an innovative use of principal component analysis as applied to residue-by-residue root-mean-square deviations values from a reference structure. This procedure allowed us to identify the aggregation-prone regions of the peptide.
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Affiliation(s)
- Mariacristina Valerio
- Dipartimento di Chimica, Università La Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italia
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16
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Wun KS, Miles LA, Crespi GAN, Wycherley K, Ascher DB, Barnham KJ, Cappai R, Beyreuther K, Masters CL, Parker MW, McKinstry WJ. Crystallization and preliminary X-ray diffraction analysis of the Fab fragment of WO2, an antibody specific for the Abeta peptides associated with Alzheimer's disease. Acta Crystallogr Sect F Struct Biol Cryst Commun 2008; 64:438-41. [PMID: 18453721 PMCID: PMC2376392 DOI: 10.1107/s1744309108011718] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2008] [Accepted: 04/23/2008] [Indexed: 11/10/2022]
Abstract
The murine monoclonal antibody WO2 specifically binds the N-terminal region of the amyloid beta peptide (Abeta) associated with Alzheimer's disease. This region of Abeta has been shown to be the immunodominant B-cell epitope of the peptide and hence is considered to be a basis for the development of immunotherapeutic strategies against this prevalent cause of dementia. Structural studies have been undertaken in order to characterize the molecular basis for antibody recognition of this important epitope. Here, details of the crystallization and X-ray analysis of the Fab fragment of the unliganded WO2 antibody in two crystal forms and of the complexes that it forms with the truncated Abeta peptides Abeta(1-16) and Abeta(1-28) are presented. These crystals were all obtained using the hanging-drop vapour-diffusion method at 295 K. Crystals of WO2 Fab were grown in polyethylene glycol solutions containing ZnSO(4); they belonged to the orthorhombic space group P2(1)2(1)2(1) and diffracted to 1.6 A resolution. The complexes of WO2 Fab with either Abeta(1-16) or Abeta(1-28) were cocrystallized from polyethylene glycol solutions. These two complex crystals grew in the same space group, P2(1)2(1)2(1), and diffracted to 1.6 A resolution. A second crystal form of WO2 Fab was grown in the presence of the sparingly soluble Abeta(1-42) in PEG 550 MME. This second form belonged to space group P2(1) and diffracted to 1.9 A resolution.
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Affiliation(s)
- Kwok S. Wun
- Biota Structural Biology Laboratory and Centre for Structural Neurobiology, St Vincent’s Institute of Medical Research, 41 Victoria Parade, Fitzroy, Victoria 3065, Australia
| | - Luke A. Miles
- Biota Structural Biology Laboratory and Centre for Structural Neurobiology, St Vincent’s Institute of Medical Research, 41 Victoria Parade, Fitzroy, Victoria 3065, Australia
- Department of Chemical and Biomolecular Engineering, The University of Melbourne, Victoria 3010, Australia
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria 3010, Australia
| | - Gabriela A. N. Crespi
- Biota Structural Biology Laboratory and Centre for Structural Neurobiology, St Vincent’s Institute of Medical Research, 41 Victoria Parade, Fitzroy, Victoria 3065, Australia
| | - Kaye Wycherley
- WEHI Biotechnology Centre, La Trobe R&D Park, Bundoora, Victoria 3086, Australia
| | - David B. Ascher
- Biota Structural Biology Laboratory and Centre for Structural Neurobiology, St Vincent’s Institute of Medical Research, 41 Victoria Parade, Fitzroy, Victoria 3065, Australia
| | - Kevin J. Barnham
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria 3010, Australia
- Department of Pathology, The University of Melbourne, Victoria 3010, Australia
- The Mental Health Research Institute of Victoria, Parkville, Victoria 3052, Australia
| | - Roberto Cappai
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria 3010, Australia
- Department of Pathology, The University of Melbourne, Victoria 3010, Australia
- The Mental Health Research Institute of Victoria, Parkville, Victoria 3052, Australia
| | | | - Colin L. Masters
- Department of Pathology, The University of Melbourne, Victoria 3010, Australia
- The Mental Health Research Institute of Victoria, Parkville, Victoria 3052, Australia
| | - Michael W. Parker
- Biota Structural Biology Laboratory and Centre for Structural Neurobiology, St Vincent’s Institute of Medical Research, 41 Victoria Parade, Fitzroy, Victoria 3065, Australia
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria 3010, Australia
| | - William J. McKinstry
- Biota Structural Biology Laboratory and Centre for Structural Neurobiology, St Vincent’s Institute of Medical Research, 41 Victoria Parade, Fitzroy, Victoria 3065, Australia
- Department of Medicine (St Vincent’s Hospital), The University of Melbourne, 41 Victoria Parade, Fitzroy 3065, Australia
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17
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Miles LA, Wun KS, Crespi GAN, Fodero-Tavoletti MT, Galatis D, Bagley CJ, Beyreuther K, Masters CL, Cappai R, McKinstry WJ, Barnham KJ, Parker MW. Amyloid-beta-anti-amyloid-beta complex structure reveals an extended conformation in the immunodominant B-cell epitope. J Mol Biol 2008; 377:181-92. [PMID: 18237744 DOI: 10.1016/j.jmb.2007.12.036] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 12/15/2007] [Accepted: 12/17/2007] [Indexed: 11/16/2022]
Abstract
Alzheimer's disease (AD) is the most common form of dementia. Amyloid-beta (A beta) peptide, generated by proteolytic cleavage of the amyloid precursor protein, is central to AD pathogenesis. Most pharmaceutical activity in AD research has focused on A beta, its generation and clearance from the brain. In particular, there is much interest in immunotherapy approaches with a number of anti-A beta antibodies in clinical trials. We have developed a monoclonal antibody, called WO2, which recognises the A beta peptide. To this end, we have determined the three-dimensional structure, to near atomic resolution, of both the antibody and the complex with its antigen, the A beta peptide. The structures reveal the molecular basis for WO2 recognition and binding of A beta. The A beta peptide adopts an extended, coil-like conformation across its major immunodominant B-cell epitope between residues 2 and 8. We have also studied the antibody-bound A beta peptide in the presence of metals known to affect its aggregation state and show that WO2 inhibits these interactions. Thus, antibodies that target the N-terminal region of A beta, such as WO2, hold promise for therapeutic development.
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Affiliation(s)
- Luke A Miles
- Biota Structural Biology Laboratory, St. Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3065, Australia
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18
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Gaggelli E, Grzonka Z, Kozłowski H, Migliorini C, Molteni E, Valensin D, Valensin G. Structural features of the Cu(ii) complex with the rat Aβ(1–28) fragment. Chem Commun (Camb) 2008:341-3. [DOI: 10.1039/b713453c] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Gaggelli E, Janicka-Klos A, Jankowska E, Kozlowski H, Migliorini C, Molteni E, Valensin D, Valensin G, Wieczerzak E. NMR studies of the Zn2+ interactions with rat and human beta-amyloid (1-28) peptides in water-micelle environment. J Phys Chem B 2007; 112:100-9. [PMID: 18072760 DOI: 10.1021/jp075168m] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Alzheimer's disease is a fatal neurodegenerative disorder involving the abnormal accumulation and deposition of peptides (amyloid-beta, Abeta) derived from the amyloid precursor protein. Here, we present the structure and the Zn2+ binding sites of human and rat Abeta(1-28) fragments in water/sodium dodecyl sulfate (SDS) micelles by using 1H NMR spectroscopy. The chemical shift variations measured after Zn2+ addition at T>310 K allowed us to assign the binding donor atoms in both rat and human zinc complexes. The Asp-1 amine, His-6 Ndelta, Glu-11 COO-, and His-13 Nepsilon of rat Abeta28 all enter the metal coordination sphere, while His-6 Ndelta, His-13, His-14 Nepsilon, Asp-1 amine, and/or Glu-11 COO- are all bound to Zn2+ in the case of human Abeta28. Finally, a comparison between the rat and human binding abilities was discussed.
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Affiliation(s)
- Elena Gaggelli
- Department of Chemistry, University of Siena, via Aldo Moro, 53-100 Siena, Italy
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20
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Rodziewicz-Motowidło S, Juszczyk P, Kołodziejczyk AS, Sikorska E, Skwierawska A, Oleszczuk M, Grzonka Z. Conformational solution studies of the SDS micelle-bound 11-28 fragment of two Alzheimer's β-amyloid variants (E22K and A21G) using CD, NMR, and MD techniques. Biopolymers 2007; 87:23-39. [PMID: 17534931 DOI: 10.1002/bip.20768] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The beta-amyloid (Abeta) is the major peptide constituent of neuritic plaques in Alzheimer's disease (AD) and its aggregation is believed to play a central role in the pathogenesis of the disease. Naturally occurring mutations resulting in changes in the Abeta sequence (pos. 21-23) are associated with familial AD-like diseases with extensive cerebrovascular pathology. It was proved that the mutations alter the aggregation ability of Abeta and its neurotoxicity. Among five mutations at positions 21-23 there are two mutations with distinct clinical characteristics and potentially distinct pathogenic mechanism-the Italian (E22K) and the Flemish (A21G) mutations. In our studies we have examined the structures of the 11-28 fragment of the Italian and Flemish Abeta variants. The fragment was chosen because it has been shown to be the most important for amyloid fibril formation. The detailed structure of both variants Abeta(11-28) was determined using CD, 2D NMR, and molecular dynamics techniques under water-SDS micelle conditions. The NMR analysis revealed two distinct sets of proton resonances for the peptides. The studies of both peptides pointed out the existence of well-defined alpha-helical conformation in the Italian mutant, whereas the Flemish was found to be unstructured with the possibility of a bent structure in the central part of the peptide.
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21
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Rainey JK, Fliegel L, Sykes BD. Strategies for dealing with conformational sampling in structural calculations of flexible or kinked transmembrane peptides. Biochem Cell Biol 2007; 84:918-29. [PMID: 17215879 DOI: 10.1139/o06-178] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Peptides corresponding to transmembrane (TM) segments from membrane proteins provide a potential route for the determination of membrane protein structure. We have determined that 2 functionally critical TM segments from the mammalian Na+/H+ exchanger display well converged structure in regions separated by break points. The flexibility of these break points results in conformational sampling in solution. A brief review of available NMR structures of helical membrane proteins demonstrates that there are a number of published structures showing similar properties. Such flexibility is likely indicative of kinks in the full-length protein. This minireview focuses on methods and protocols for NMR structure calculation and analysis of peptide structures under conditions of conformational sampling. The methods outlined allow the identification and analysis of structured peptides containing break points owing to conformational sampling and the differentiation between oligomerization and ensemble-averaged observation of multiple peptide conformations.
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Affiliation(s)
- Jan K Rainey
- Protein Engineering Network of Centres of Excellence and Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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22
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23
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Jaroniec CP, Kaufman JD, Stahl SJ, Viard M, Blumenthal R, Wingfield PT, Bax A. Structure and dynamics of micelle-associated human immunodeficiency virus gp41 fusion domain. Biochemistry 2006; 44:16167-80. [PMID: 16331977 DOI: 10.1021/bi051672a] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The N-terminal fusion domain of the HIV-1 gp41 envelope glycoprotein is responsible for initiating the fusion of viral and cellular membranes, leading to the subsequent infection of the host cell by HIV-1. We have investigated the backbone structure and dynamics of the 30 N-terminal residues of HIV-1 gp41 in membrane-mimicking environments using NMR spectroscopy and (15)N- and (15)N,(13)C,(2)H-labeled peptides. Similar (15)N-(1)H HSQC spectra were obtained in a variety of detergents, including SDS, DPC, mixed DPC/SDS, and LPPG micelles, indicating that the peptide structure is not strongly influenced by the type of detergent used. Detailed characterization was carried out in SDS micelles, where the long-term sample stability was found to be optimal. In addition to J-coupling and NOE restraints, a nearly complete set of backbone residual dipolar coupling restraints was recorded for the fusion domain-micelle complex aligned with respect to the magnetic field using a stretched polyacrylamide gel. Backbone amide (15)N spin relaxation and amide hydrogen exchange rates with the solvent were also measured. The ensemble of NMR structures reveals an uninterrupted alpha-helix for the least mobile residues (S(2) > 0.65), Ile-4 to Met-19, with transient helical character extending up to Ala-22. A 12-residue (Ile-4 to Ala-15) segment is fully shielded from solvent, with Gly-3 and Gly-16 found at micelle-solvent interfaces. Residues external to the micelle exhibit enhanced picosecond to nanosecond time scale dynamics relative to the residues buried in the micelle, and their mobility increases with the distance from the micelle.
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Affiliation(s)
- Christopher P Jaroniec
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, USA.
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24
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Morgan C, Colombres M, Nuñez MT, Inestrosa NC. Structure and function of amyloid in Alzheimer's disease. Prog Neurobiol 2004; 74:323-49. [PMID: 15649580 DOI: 10.1016/j.pneurobio.2004.10.004] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Accepted: 10/26/2004] [Indexed: 12/21/2022]
Abstract
This review is focused on the structure and function of Alzheimer's amyloid deposits. Amyloid formation is a process in which normal well-folded cellular proteins undergo a self-assembly process that leads to the formation of large and ordered protein structures. Amyloid deposition, oligomerization, and higher order polymerization, and the structure adopted by these assemblies, as well as their functional relationship with cell biology are underscored. Numerous efforts have been directed to elucidate these issues and their relation with senile dementia. Significant advances made in the last decade in amyloid structure, dynamics and cell biology are summarized and discussed. The mechanism of amyloid neurotoxicity is discussed with emphasis on the Wnt signaling pathway. This review is focused on Alzheimer's amyloid fibrils in general and has been divided into two parts dealing with the structure and function of amyloid.
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Affiliation(s)
- Carlos Morgan
- Centro FONDAP de Regulación Celular y Patología Joaquín V. Luco, MIFAB, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, P.O. Box 114-D, Santiago, Chile
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25
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Mascioni A, Porcelli F, Ilangovan U, Ramamoorthy A, Veglia G. Conformational preferences of the amylin nucleation site in SDS micelles: an NMR study. Biopolymers 2003; 69:29-41. [PMID: 12717720 DOI: 10.1002/bip.10305] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Human islet amyloid polypeptide (hIAPP), or amylin, is a 37 amino acid hormone secreted by pancreatic beta-cells. hIAPP constitutes approximately 90% of the amyloid deposits found in type II diabetic patients. It has been shown that the central region of the peptide (hIAPP(20-29)) constitutes the nucleation site for the amyloidogenic process with F23 playing a key role in the formation of the beta-pleated structures. In addition, it has been proposed that an important stage in the cytotoxicity of hIAPP is its interaction with the beta-cell membranes. As a first step toward the characterization of the interaction of hIAPP with cell membranes, we determined conformational preferences of hIAPP(20-29) in membrane-mimicking environments. We found that upon interacting with negatively charged micelles, the dominant conformation of hIAPP(20-29) is a distorted type I beta-turn centered on residues F23 and G24, with F23, A25, and I26 forming a small hydrophobic cluster that may facilitate the interaction of this peptide with the membrane bilayer. Moreover, we were able to elucidate the topological orientation of the peptide that is absorbed on the micelle surface, with the hydrophobic cluster oriented toward the hydrocarbon region of the micelles and both N- and C-termini exposed to the solvent.
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26
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Watanabe K, Segawa T, Nakamura K, Kodaka M, Konakahara T, Okuno H. Identification of the molecular interaction site of amyloid beta peptide by using a fluorescence assay. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2001; 58:342-6. [PMID: 11606220 DOI: 10.1034/j.1399-3011.2001.00920.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Beta-amyloid peptides (Abeta) are the main protein components of neuritic plaques and are important in the pathogenesis of Alzheimer's disease. It is reported that Abeta itself is not toxic; however, it becomes toxic to neuronal cells once it has aggregated into amyloid fibrils by peptide-peptide interactions. In this study, to specify the molecular mechanism of aggregation, a novel fluorescence assay was designed. For this purpose, possible partial peptides (38 types of 5-mer) were synthesized on solid-phase. The molecular interactions were examined by a fluorescence probe possessing Lys-Leu-Val-Phe-Phe (KLVFF) as a molecular recognition site. KLVFF is known to be a minimum sequence for formation of the Abeta aggregate. A specific interaction was observed between labeled and immobilized KLVFF. It suggests that the aggregation of Abeta was controlled by the recognition of KLVFF itself by hydrophobic and electrostatic interactions.
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Affiliation(s)
- K Watanabe
- National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
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