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Guglielmelli A, Bartucci R, Rizzuti B, Palermo G, Guzzi R, Strangi G. The interaction of tryptophan enantiomers with model membranes is modulated by polar head type and physical state of phospholipids. Colloids Surf B Biointerfaces 2023; 224:113216. [PMID: 36848783 DOI: 10.1016/j.colsurfb.2023.113216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 01/29/2023] [Accepted: 02/21/2023] [Indexed: 02/25/2023]
Abstract
The mutual influence of chiral bioactive molecules and supramolecular assemblies is currently being studied in many research fields, including medical-pharmaceutical applications. Model membranes of phospholipids, such as the zwitterionic dipalmitoylphosphatidylcholine (DPPC) and the anionic dipalmitoylphosphatidylglycerol (DPPG), interact with a variety of chiral compounds that include amino acids. In this work, the interaction of tryptophan enantiomers, L-Trp and D-Trp, on DPPC and DPPG bilayers was investigated by using differential scanning calorimetry, attenuated total reflectance-Fourier transform infrared and spin-label electron spin resonance spectroscopies as well as molecular docking simulations. The results show that Trp enantiomers slightly perturb the bilayer thermotropic phase transitions. For both membranes, O atoms in the carbonyl groups have a propensity to act as acceptors of a (weak) hydrogen bond. The Trp chiral forms also promote formation of hydrogen bonds and/or hydration in the PO2- moiety of the phosphate group, especially for the DPPC bilayer. In contrast, they interact more closely with the glycerol group of DPPG polar head. Only for DPPC bilayers, both enantiomers increase the packing of the first hydrocarbon chain segments for temperatures through the gel state, whereas they do not affect the lipid chain order and mobility in the fluid state. The results are consistent with a Trp association in the upper region of the bilayers without permeation in the innermost hydrophobic region. The findings suggest that neutral and anionic lipid bilayers are differently sensitive to amino acid chirality.
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Affiliation(s)
- Alexa Guglielmelli
- Department of Physics, NLHT Lab., University of Calabria, 87036 Rende, Italy; CNR NANOTEC-Institute of Nanotechnology, SS Rende (CS), 87036 Rende, Italy
| | - Rosa Bartucci
- Department of Chemistry and Chemical Technologies, Molecular Biophysics Laboratory, University of Calabria, 87036 Rende, Italy.
| | - Bruno Rizzuti
- CNR NANOTEC-Institute of Nanotechnology, SS Rende (CS), 87036 Rende, Italy; Institute for Biocomputation and Physics of Complex Systems (BIFI), Joint Unit GBsC-CSIC-BIFI, University of Zaragoza, 50018 Zaragoza, Spain
| | - Giovanna Palermo
- Department of Physics, NLHT Lab., University of Calabria, 87036 Rende, Italy; CNR NANOTEC-Institute of Nanotechnology, SS Rende (CS), 87036 Rende, Italy
| | - Rita Guzzi
- CNR NANOTEC-Institute of Nanotechnology, SS Rende (CS), 87036 Rende, Italy; Department of Physics, Molecular Biophysics Laboratory, University of Calabria, 87036 Rende, Italy
| | - Giuseppe Strangi
- Department of Physics, NLHT Lab., University of Calabria, 87036 Rende, Italy; CNR NANOTEC-Institute of Nanotechnology, SS Rende (CS), 87036 Rende, Italy; Department of Physics, Case Western Reserve University, 2076 Adelbert Rd, Cleveland, OH 44106 USA
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2
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Probable Reasons for Neuron Copper Deficiency in the Brain of Patients with Alzheimer’s Disease: The Complex Role of Amyloid. INORGANICS 2022. [DOI: 10.3390/inorganics10010006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Alzheimer’s disease is a progressive neurodegenerative disorder that eventually leads the affected patients to die. The appearance of senile plaques in the brains of Alzheimer’s patients is known as a main symptom of this disease. The plaques consist of different components, and according to numerous reports, their main components include beta-amyloid peptide and transition metals such as copper. In this disease, metal dyshomeostasis leads the number of copper ions to simultaneously increase in the plaques and decrease in neurons. Copper ions are essential for proper brain functioning, and one of the possible mechanisms of neuronal death in Alzheimer’s disease is the copper depletion of neurons. However, the reason for the copper depletion is as yet unknown. Based on the available evidence, we suggest two possible reasons: the first is copper released from neurons (along with beta-amyloid peptides), which is deposited outside the neurons, and the second is the uptake of copper ions by activated microglia.
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3
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Törnquist M, Linse S. Chiral Selectivity of Secondary Nucleation in Amyloid Fibril Propagation. Angew Chem Int Ed Engl 2021; 60:24008-24011. [PMID: 34494356 PMCID: PMC8596840 DOI: 10.1002/anie.202108648] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Indexed: 01/02/2023]
Abstract
Chirality is a fundamental feature of asymmetric molecules and of critical importance for intermolecular interactions. The growth of amyloid fibrils displays a strong enantioselectivity, which is manifested as elongation through the addition of monomers of the same, but not opposite, chirality as the parent aggregate. Here we ask whether also secondary nucleation on the surface of amyloid fibrils, of relevance for toxicity, is governed by the chirality of the nucleating monomers. We use short amyloid peptides (Aβ20‐34 and IAPP20‐29) with all residues as L‐ or all D‐enantiomer in self and cross‐seeding experiments with low enough seed concentration that any acceleration of fibril formation is dominated by secondary nucleation. We find a strong enantio‐specificity of this auto‐catalytic process with secondary nucleation being observed in the self‐seeding experiments only. The results highlight a role of secondary nucleation in strain propagation.
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Affiliation(s)
- Mattias Törnquist
- Biochemistry and Structural Biology, Lund University, Kemicentrum, Box 118, 22100, Lund, Sweden
| | - Sara Linse
- Biochemistry and Structural Biology, Lund University, Kemicentrum, Box 118, 22100, Lund, Sweden
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4
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Törnquist M, Linse S. Chiral Selectivity of Secondary Nucleation in Amyloid Fibril Propagation. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202108648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Mattias Törnquist
- Biochemistry and Structural Biology Lund University Kemicentrum, Box 118 22100 Lund Sweden
| | - Sara Linse
- Biochemistry and Structural Biology Lund University Kemicentrum, Box 118 22100 Lund Sweden
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5
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Foley AR, Raskatov JA. Understanding and controlling amyloid aggregation with chirality. Curr Opin Chem Biol 2021; 64:1-9. [PMID: 33610939 PMCID: PMC8368077 DOI: 10.1016/j.cbpa.2021.01.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 01/11/2021] [Accepted: 01/16/2021] [Indexed: 12/22/2022]
Abstract
Amyloid aggregation and human disease are inextricably linked. Examples include Alzheimer disease, Parkinson disease, and type II diabetes. While seminal advances on the mechanistic understanding of these diseases have been made over the last decades, controlling amyloid fibril formation still represents a challenge, and it is a subject of active research. In this regard, chiral modifications have increasingly been proved to offer a particularly well-suited approach toward accessing to previously unknown aggregation pathways and to provide with novel insights on the biological mechanisms of action of amyloidogenic peptides and proteins. Here, we summarize recent advances on how the use of mirror-image peptides/proteins and d-amino acid incorporations have helped modulate amyloid aggregation, offered new mechanistic tools to study cellular interactions, and allowed us to identify key positions within the peptide/protein sequence that influence amyloid fibril growth and toxicity.
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Affiliation(s)
- Alejandro R Foley
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, 95064, USA
| | - Jevgenij A Raskatov
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, 95064, USA.
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6
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Rajput S, Sani MA, Keizer DW, Separovic F. Utilizing magnetic resonance techniques to study membrane interactions of amyloid peptides. Biochem Soc Trans 2021; 49:1457-1465. [PMID: 34156433 PMCID: PMC8286822 DOI: 10.1042/bst20201244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 05/26/2021] [Accepted: 06/02/2021] [Indexed: 12/30/2022]
Abstract
Alzheimer's disease (AD) is a common neurodegenerative condition that involves the extracellular accumulation of amyloid plaques predominantly consisting of Aβ peptide aggregates. The amyloid plaques and soluble oligomeric species of Aβ are believed to be the major cause of synaptic dysfunction in AD brain and their cytotoxic mechanisms have been proposed to involve interactions with cell membranes. In this review, we discuss our solid-state nuclear magnetic resonance (ssNMR) studies of Aβ interactions with model membranes.
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Affiliation(s)
- Sunnia Rajput
- Bio21 Molecular Science & Biotechnology Institute, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Marc-Antoine Sani
- Bio21 Molecular Science & Biotechnology Institute, University of Melbourne, Melbourne, VIC 3010, Australia
- School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia
| | - David W. Keizer
- Bio21 Molecular Science & Biotechnology Institute, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Frances Separovic
- Bio21 Molecular Science & Biotechnology Institute, University of Melbourne, Melbourne, VIC 3010, Australia
- School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia
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7
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Shi JM, Zhu L, Lan X, Zhao DW, He YJ, Sun ZQ, Wu D, Li HY. Endocytosis Is a Key Mode of Interaction between Extracellular β-Amyloid and the Cell Membrane. Biophys J 2020; 119:1078-1090. [PMID: 32857960 PMCID: PMC7499104 DOI: 10.1016/j.bpj.2020.07.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/21/2020] [Accepted: 07/08/2020] [Indexed: 11/23/2022] Open
Abstract
Interactions between amyloid-β peptide (Aβ) and the cell membrane include interaction with membrane lipids and binding to membrane receptors, both of which are considered to be the toxicity mechanisms of Aβ. However, it is unclear whether both mechanisms lead to cytotoxicity. Thus, we aimed to analyze these two mechanisms of Aβ42 interaction with cell membranes under different Aβ aggregation states. To this end, model membrane experiments were conducted. Quantitative analysis of Aβ42 monomers or oligomers bound to the membrane of neuro-2a cells was also performed, and laser confocal microscopy was employed to assess endocytosis of FITC-Aβ42 monomers or oligomers by neuro-2a cells. We found that the binding capacity of Aβ42 to membrane lipids was weak and that the amount of Aβ42 bound to membrane lipids was low. Moreover, clathrin-mediated endocytosis of Aβ42 oligomers by neuro-2a cells was observed. Endocytosis serves as a key mode of interaction between extracellular Aβ42 and neurons. These findings provide insights into the mechanisms underlying Aβ oligomer metabolism.
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Affiliation(s)
- Jing-Ming Shi
- School of Medicine, Xizang Minzu University, Xian' yang, Shaanxi, P.R. China
| | - Li Zhu
- School of Life Sciences, Lanzhou University, Lanzhou, P.R. China
| | - Xi Lan
- MOE Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, Shaanxi, P. R. China
| | - Duan-Wei Zhao
- Gansu Provincial Institute of Drug Control, Lanzhou, P.R. China
| | - Yong-Jun He
- School of Medicine, Xizang Minzu University, Xian' yang, Shaanxi, P.R. China
| | - Zheng-Qi Sun
- School of Medicine, Xizang Minzu University, Xian' yang, Shaanxi, P.R. China
| | - Di Wu
- School of Life Sciences, Lanzhou University, Lanzhou, P.R. China
| | - Hai-Yun Li
- MOE Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, Shaanxi, P. R. China.
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8
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Annexin A5 prevents amyloid-β-induced toxicity in choroid plexus: implication for Alzheimer's disease. Sci Rep 2020; 10:9391. [PMID: 32523019 PMCID: PMC7286910 DOI: 10.1038/s41598-020-66177-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 05/09/2020] [Indexed: 12/11/2022] Open
Abstract
In Alzheimer’s disease (AD) amyloid-β (Aβ) deposits may cause impairments in choroid plexus, a specialised brain structure which forms the blood–cerebrospinal fluid (CSF) barrier. We previously carried out a mass proteomic-based study in choroid plexus from AD patients and we found several differentially regulated proteins compared with healthy subjects. One of these proteins, annexin A5, was previously demonstrated implicated in blocking Aβ-induced cytotoxicity in neuronal cell cultures. Here, we investigated the effects of annexin A5 on Aβ toxicity in choroid plexus. We used choroid plexus tissue samples and CSF from mild cognitive impairment (MCI) and AD patients to analyse Aβ accumulation, cell death and annexin A5 levels compared with control subjects. Choroid plexus cell cultures from rats were used to analyse annexin A5 effects on Aβ-induced cytotoxicity. AD choroid plexus exhibited progressive reduction of annexin A5 levels along with progressive increased Aβ accumulation and cell death as disease stage was higher. On the other hand, annexin A5 levels in CSF from patients were found progressively increased as the disease stage increased in severity. In choroid plexus primary cultures, Aβ administration reduced endogenous annexin A5 levels in a time-course dependent manner and simultaneously increased annexin A5 levels in extracellular medium. Annexin A5 addition to choroid plexus cell cultures restored the Aβ-induced impairments on autophagy flux and apoptosis in a calcium-dependent manner. We propose that annexin A5 would exert a protective role in choroid plexus and this protection is lost as Aβ accumulates with the disease progression. Then, brain protection against further toxic insults would be jeopardised.
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9
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Kravenska Y, Nieznanska H, Nieznanski K, Lukyanetz E, Szewczyk A, Koprowski P. The monomers, oligomers, and fibrils of amyloid-β inhibit the activity of mitoBK Ca channels by a membrane-mediated mechanism. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183337. [PMID: 32380169 DOI: 10.1016/j.bbamem.2020.183337] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Revised: 04/25/2020] [Accepted: 04/28/2020] [Indexed: 02/08/2023]
Abstract
A causative agent of Alzheimer's disease (AD) is a short amphipathic peptide called amyloid beta (Aβ). Aβ monomers undergo structural changes leading to their oligomerization or fibrillization. The monomers as well as all aggregated forms of Aβ, i.e., oligomers, and fibrils, can bind to biological membranes, thereby modulating membrane mechanical properties. It is also known that some isoforms of the large-conductance calcium-activated potassium (BKCa) channel, including the mitochondrial BKCa (mitoBKCa) channel, respond to mechanical changes in the membrane. Here, using the patch-clamp technique, we investigated the impact of full-length Aβ (Aβ1-42) and its fragment, Aβ25-35, on the activity of mitoBKCa channels. We found that all forms of Aβ inhibited the activity of the mitoBKCa channel in a concentration-dependent manner. Since monomers, oligomers, and fibrils of Aβ exhibit different molecular characteristics and structures, we hypothesized that the inhibition was not due to direct peptide-protein interactions but rather to membrane-binding of the Aβ peptides. Our findings supported this hypothesis by showing that Aβ peptides block mitoBKCa channels irrespective of the side of the membrane to which they are applied. In addition, we found that the enantiomeric peptide, D-Aβ1-42, demonstrated similar inhibitory activity towards mitoBKCa channels. As a result, we proposed a general model in which all Aβ forms i.e., monomers, oligomers, and amyloid fibrils, contribute to the progression of AD by exerting a modulatory effect on mechanosensitive membrane components.
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Affiliation(s)
- Yevheniia Kravenska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology PAS, Pasteura str. 3, Warsaw 02-093, Poland; Department of Biophysics of Ion Channels, Bogomoletz Institute of Physiology NASU, Bogomoletz str. 4, Kyiv 01-024, Ukraine.
| | - Hanna Nieznanska
- Laboratory of Electron Microscopy, Nencki Institute of Experimental Biology PAS, Pasteura str. 3, Warsaw 02-093, Poland
| | - Krzysztof Nieznanski
- Laboratory of Molecular Basis of Cell Motility, Nencki Institute of Experimental Biology PAS, Pasteura str. 3, Warsaw 02-093, Poland
| | - Elena Lukyanetz
- Department of Biophysics of Ion Channels, Bogomoletz Institute of Physiology NASU, Bogomoletz str. 4, Kyiv 01-024, Ukraine
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology PAS, Pasteura str. 3, Warsaw 02-093, Poland
| | - Piotr Koprowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology PAS, Pasteura str. 3, Warsaw 02-093, Poland
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10
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Przygońska K, Pacewicz M, Sadowska W, Poznański J, Bal W, Dadlez M. His6, His13, and His14 residues in Aβ 1-40 peptide significantly and specifically affect oligomeric equilibria. Sci Rep 2019; 9:9449. [PMID: 31263161 PMCID: PMC6602940 DOI: 10.1038/s41598-019-45988-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 06/20/2019] [Indexed: 11/12/2022] Open
Abstract
Oligomers of Aβ peptide are implicated as the most probable causative agent in Alzheimer's disease. However, their structural properties remain elusive due to the dynamic and heterogeneous character of oligomeric species coexisting in solution. Nevertheless, new approaches, mainly based on mass spectrometry, provide unique access to these different structural forms. Using these methods, we previously showed that the N-terminal, non-amyloidogenic region of Aβ is involved in the network of interactions specifically stabilizing oligomers. In the present study, we identified three histidine residues as active participants in this network. Detailed knowledge of the structural features that are potentially important for oligomer-mediated neurotoxicity is a prerequisite for the rational design of oligomerization modifiers.
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Affiliation(s)
- Kaja Przygońska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Magdalena Pacewicz
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Wiktoria Sadowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
- Department of Chemistry, University of Warsaw, Warsaw, Poland
| | - Jarosław Poznański
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Wojciech Bal
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Michał Dadlez
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.
- Institute of Genetics and Biotechnology, Department of Biology, University of Warsaw, Warsaw, Poland.
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11
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Dutta S, Finn TS, Kuhn AJ, Abrams B, Raskatov JA. Chirality Dependence of Amyloid β Cellular Uptake and a New Mechanistic Perspective. Chembiochem 2019; 20:1023-1026. [PMID: 30550626 PMCID: PMC6517241 DOI: 10.1002/cbic.201800708] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Indexed: 01/08/2023]
Abstract
Amyloid β is an inherently disordered peptide that can form diverse neurotoxic aggregates, and its 42-amino-acid isoform is believed to be the agent responsible for Alzheimer's disease (AD). Cellular uptake of the peptide is a pivotal step for it to be able to exert many of its toxic actions. The cellular uptake process is complex, and numerous competing internalization pathways have been proposed. To date, it remains unclear which of the uptake mechanisms are particularly important for the overall process, and improvement of this understanding is needed, so that better molecular AD therapeutics can be designed. Chirality can be used as a unique tool to study this process, because some of the proposed mechanisms are expected to proceed in stereoselective fashion, whereas others are not. To shed light on this important issue, we synthesized fluorescently labeled enantiomers of amyloid β and quantified their cellular uptake, finding that uptake occurs in stereoselective fashion, with a typical preference for the l stereoisomer of ≈5:1. This suggests that the process is predominantly receptor-mediated, with likely minor contributions of non-stereoselective mechanisms.
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Affiliation(s)
- Subrata Dutta
- Dept. of Chemistry and Biochemistry, UCSC, 1156 High Street, Santa Cruz, California, USA
| | - Thomas S. Finn
- Dept. of Chemistry and Biochemistry, UCSC, 1156 High Street, Santa Cruz, California, USA
| | - Ariel J. Kuhn
- Dept. of Chemistry and Biochemistry, UCSC, 1156 High Street, Santa Cruz, California, USA
| | - Benjamin Abrams
- Dept. of Biomolecular Engineering, Life Sciences Microscopy Center, UCSC, 1156 High Street, Santa Cruz, 95064 CA, USA
| | - Jevgenij A. Raskatov
- Dept. of Chemistry and Biochemistry, UCSC, 1156 High Street, Santa Cruz, California, USA
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12
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Liu W, Dong X, Sun Y. d-Enantiomeric RTHLVFFARK-NH 2: A Potent Multifunctional Decapeptide Inhibiting Cu 2+-Mediated Amyloid β-Protein Aggregation and Remodeling Cu 2+-Mediated Amyloid β Aggregates. ACS Chem Neurosci 2019; 10:1390-1401. [PMID: 30650306 DOI: 10.1021/acschemneuro.8b00440] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Aggregation of amyloid β-protein (Aβ) into β-sheet-rich plaques is a general feature of Alzheimer's disease (AD). Homeostasis dysregulation of Cu2+ mediates Aβ to form high cytotoxic aggregates, which causes cell damage by generation of reactive oxygen species (ROS). To improve the inhibitory potency and explore the multifaceted functions of our previously designed decapeptide, RTHLVFFARK-NH2 (RK10), we have herein reformulated the decapeptide into its d-enantiomer, rk10, and the effects of chirality on Aβ aggregation, Cu2+-mediated Aβ aggregations, and aggregate-remodeling effects were investigated. The results revealed the following: (1) The d-enantiomer presented enhanced inhibitory potency on Aβ fibrillogenesis in comparison to RK10; rk10 and RK10 increased the cell viability from 60% to 91% and 71%, respectively, at an equimolar concentration to Aβ. (2) The enantiomers were chemically equivalent to Cu2+ chelation, ROS suppression and oxidative damage rescue. (3) The d-enantiomer exhibited higher performance to inhibit Cu2+-mediated Aβ aggregation, and more significantly attenuated the cytotoxicity caused by Aβ42-Cu2+ complex than RK10. Cell viability was rescued from 51% to 89% and 74% by coincubating with rk10 and RK10 at 50 μM, respectively. Intracellular ROS levels generated by Aβ42 and Aβ42-Cu2+ species were also remarkably decreased by treating with rk10. (4) The enantiomers could remodel mature Aβ42-Cu2+ aggregates by Cu2+ chelation, and rk10 showed higher performance than RK10, as evidenced by the enhanced cell viability from 57% to 86% by RK10 and to 96% by rk10. The d-enantiomer also showed higher ability than RK10 on protecting the disrupted species from reaggregation. Taken together, D-chiral derivatization of the decapeptide resulted in a potent multifunctional agent in inhibiting Cu2+-mediated Aβ aggregation and remodeling mature Aβ-Cu2+ species. To the best of our knowledge, this is the first investigation on the chirality effect of a multifunctional peptide inhibitor on Cu2+-mediated Aβ aggregation and on the remodeling effect of mature Aβ-Cu2+ aggregates. The work provides new insights into the critical role of chirality in the multifaceted functions of peptide inhibitors against amyloid formation and its toxicity.
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Affiliation(s)
- Wei Liu
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300354, China
| | - Xiaoyan Dong
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300354, China
| | - Yan Sun
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300354, China
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13
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Young TR, Wedd AG, Xiao Z. Evaluation of Cu(i) binding to the E2 domain of the amyloid precursor protein - a lesson in quantification of metal binding to proteins via ligand competition. Metallomics 2019; 10:108-119. [PMID: 29215101 DOI: 10.1039/c7mt00291b] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The extracellular domain E2 of the amyloid precursor protein (APP) features a His-rich metal-binding site (denoted as the M1 site). In conjunction with surrounding basic residues, the site participates in interactions with components of the extracellular matrix including heparins, a class of negatively charged polysaccharide molecules of varying length. This work studied the chemistry of Cu(i) binding to APP E2 with the probe ligands Bcs, Bca, Fz and Fs. APP E2 forms a stable Cu(i)-mediated ternary complex with each of these anionic ligands. The complex with Bca was selected for isolation and characterization and was demonstrated, by native ESI-MS analysis, to have the stoichiometry E2 : Cu(i) : Bca = 1 : 1 : 1. Formation of these ternary complexes is specific for the APP E2 domain and requires Cu(i) coordination to the M1 site. Mutation of the M1 site was consistent with the His ligands being part of the E2 ligand set. It is likely that interactions between the negatively charged probe ligands and a positively charged patch on the surface of APP E2 are one aspect of the generation of the stable ternary complexes. Their formation prevented meaningful quantification of the affinity of Cu(i) binding to the M1 site with these probe ligands. However, the ternary complexes are disrupted by heparin, allowing reliable determination of a picomolar Cu(i) affinity for the E2/heparin complex with the Fz or Bca probe ligands. This is the first documented example of the formation of stable ternary complexes between a Cu(i) binding protein and a probe ligand. The ready disruption of the complexes by heparin identified clear 'tell-tale' signs for diagnosis of ternary complex formation and allowed a systematic review of conditions and criteria for reliable determination of affinities for metal binding via ligand competition. This study also provides new insights into a potential correlation of APP functions regulated by copper binding and heparin interaction.
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Affiliation(s)
- Tessa R Young
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
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14
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Khan AW, Ziemann M, Rafehi H, Maxwell S, Ciccotosto GD, El-Osta A. MeCP2 interacts with chromosomal microRNAs in brain. Epigenetics 2018; 12:1028-1037. [PMID: 29412786 DOI: 10.1080/15592294.2017.1391429] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Although methyl CpG binding domain protein-2 (MeCP2) is commonly understood to function as a silencing factor at methylated DNA sequences, recent studies also show that MeCP2 can bind unmethylated sequences and coordinate gene activation. MeCP2 displays broad binding patterns throughout the genome, with high expression levels similar to histone H1 in neurons. Despite its significant presence in the brain, only subtle gene expression changes occur in the absence of MeCP2. This may reflect a more complex regulatory mechanism of MeCP2 to complement chromatin binding. Using an RNA immunoprecipitation of native chromatin technique, we identify MeCP2 interacting microRNAs in mouse primary cortical neurons. In addition, comparison with mRNA sequencing data from Mecp2-null mice suggests that differentially expressed genes may indeed be targeted by MeCP2-interacting microRNAs. These findings highlight the MeCP2 interaction with microRNAs that may modulate its binding with chromatin and regulate gene expression.
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Affiliation(s)
- Abdul Waheed Khan
- a Central Clinical School, Faculty of Medicine , Monash University , Victoria , Australia.,b Baker IDI Heart and Diabetes Institute , The Alfred Medical Research and Education Precinct , Melbourne , Victoria 3004 , Australia.,c Department of Pathology , The University of Melbourne , Parkville , Victoria , Australia
| | - Mark Ziemann
- a Central Clinical School, Faculty of Medicine , Monash University , Victoria , Australia.,b Baker IDI Heart and Diabetes Institute , The Alfred Medical Research and Education Precinct , Melbourne , Victoria 3004 , Australia
| | - Haloom Rafehi
- a Central Clinical School, Faculty of Medicine , Monash University , Victoria , Australia.,b Baker IDI Heart and Diabetes Institute , The Alfred Medical Research and Education Precinct , Melbourne , Victoria 3004 , Australia
| | - Scott Maxwell
- a Central Clinical School, Faculty of Medicine , Monash University , Victoria , Australia.,b Baker IDI Heart and Diabetes Institute , The Alfred Medical Research and Education Precinct , Melbourne , Victoria 3004 , Australia
| | - Giuseppe D Ciccotosto
- c Department of Pathology , The University of Melbourne , Parkville , Victoria , Australia.,d Bio21 Molecular science and Biotechnology Institute , Victoria , Australia
| | - Assam El-Osta
- a Central Clinical School, Faculty of Medicine , Monash University , Victoria , Australia.,b Baker IDI Heart and Diabetes Institute , The Alfred Medical Research and Education Precinct , Melbourne , Victoria 3004 , Australia.,c Department of Pathology , The University of Melbourne , Parkville , Victoria , Australia.,e Hong Kong Institute of Diabetes and Obesity, Prince of Wales Hospital , The Chinese University of Hong Kong , Hong Kong SAR
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15
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Jamasbi E, Separovic F, Hossain MA, Ciccotosto GD. Phosphorylation of a full length amyloid-β peptide modulates its amyloid aggregation, cell binding and neurotoxic properties. MOLECULAR BIOSYSTEMS 2018. [PMID: 28642958 DOI: 10.1039/c7mb00249a] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Amyloid beta peptide (Aβ) is the major protein component of the amyloid plaques that are present in the brains of Alzheimer's disease (AD) patients. Aβ42 peptide is a known neurotoxic agent that binds to neurons and, under specific aggregation conditions, triggers cell death. Aβ peptide can undergo specific amino acid posttranslational modifications, such as phosphorylation, that are important for modulating its proteolytic degradation, aggregation, binding to lipid membranes and neurotoxic functions. Peptides phosphorylated at serine 8 in full-length Aβ42 (pAβ42) were synthesised and compared to native Aβ42 peptide. Their secondary structures, aggregation properties and interactions with plasma membranes of primary cortical neurons were investigated. The results revealed that pAβ42 has increased β-sheet formation with rapid amyloid formation in a synthetic lipid environment, which was associated with increased cellular binding but concomitant diminished neurotoxicity. Our data support the notion that phosphorylation of Aβ42 promotes the formation of amyloid plaques in the brain, which lack the neurotoxic properties associated with oligomeric species causing pathogenesis in AD.
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Affiliation(s)
- Elaheh Jamasbi
- School of Chemistry and Bio21 Institute, The University of Melbourne, VIC 3010, Australia
| | - Frances Separovic
- School of Chemistry and Bio21 Institute, The University of Melbourne, VIC 3010, Australia
| | - Mohammed Akhter Hossain
- School of Chemistry and Bio21 Institute, The University of Melbourne, VIC 3010, Australia and The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, VIC 3010, Australia.
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16
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Jamasbi E, Hossain MA, Tan M, Separovic F, Ciccotosto GD. Fluorescence imaging of the interaction of amyloid beta 40 peptides with live cells and model membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1609-1615. [PMID: 29408451 DOI: 10.1016/j.bbamem.2018.01.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 01/23/2018] [Accepted: 01/27/2018] [Indexed: 11/30/2022]
Abstract
Amyloid beta peptides (Aβ) found in plaques in the brain have been widely recognised as a hallmark of Alzheimer's disease although the underlying mechanism is still unknown. Aβ40 and Aβ40(A2T) peptides were synthesized and their effects on neuronal cells are reported together with the effect of tetramer forms of the peptides. ThT assay revealed that mutation affected the lag time and aggregation and the presence of lipid vesicles changed the fibril formation profile for both peptides. The A2T mutation appeared to reduce cytotoxicity and lessen binding of Aβ40 peptides to neuronal cells. Fluorescence microscopy of the interaction between Aβ40 peptides and giant unilamellar vesicles revealed that both peptides led to formation of smaller vesicles although the tetramer of Aβ(A2T) appeared to promote vesicle aggregation. This article is part of a Special Issue entitled: Protein Aggregation and Misfolding at the Cell Membrane Interface edited by Ayyalusamy Ramamoorthy.
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Affiliation(s)
- Elaheh Jamasbi
- School of Chemistry, Bio21 Institute, The University of Melbourne, VIC 3010, Australia
| | - Mohammed Akhter Hossain
- School of Chemistry, Bio21 Institute, The University of Melbourne, VIC 3010, Australia; The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, VIC 3010, Australia
| | - Marsha Tan
- Department of Pathology, The University of Melbourne, VIC 3010, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, The University of Melbourne, VIC 3010, Australia.
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17
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Bagheri S, Squitti R, Haertlé T, Siotto M, Saboury AA. Role of Copper in the Onset of Alzheimer's Disease Compared to Other Metals. Front Aging Neurosci 2018; 9:446. [PMID: 29472855 PMCID: PMC5810277 DOI: 10.3389/fnagi.2017.00446] [Citation(s) in RCA: 130] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 12/28/2017] [Indexed: 12/14/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder that is characterized by amyloid plaques in patients' brain tissue. The plaques are mainly made of β-amyloid peptides and trace elements including Zn2+, Cu2+, and Fe2+. Some studies have shown that AD can be considered a type of metal dyshomeostasis. Among metal ions involved in plaques, numerous studies have focused on copper ions, which seem to be one of the main cationic elements in plaque formation. The involvement of copper in AD is controversial, as some studies show a copper deficiency in AD, and consequently a need to enhance copper levels, while other data point to copper overload and therefore a need to reduce copper levels. In this paper, the role of copper ions in AD and some contradictory reports are reviewed and discussed.
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Affiliation(s)
- Soghra Bagheri
- Medical Biology Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Rosanna Squitti
- Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio-Fatebenefratelli, Brescia, Italy
| | - Thomas Haertlé
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
- UR 1268 Biopolymères Interactions Assemblages, Institut National de la Recherche Agronomique, Equipe Fonctions et Interactions des Protéines, Nantes, France
- Department of Animal Nutrition and Feed Management, Poznan University of Life Sciences, Poznań, Poland
| | | | - Ali A. Saboury
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
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18
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Dutta S, Foley AR, Warner CJA, Zhang X, Rolandi M, Abrams B, Raskatov JA. Suppression of Oligomer Formation and Formation of Non‐Toxic Fibrils upon Addition of Mirror‐Image Aβ42 to the Natural
l
‐Enantiomer. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201706279] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Subrata Dutta
- Dept. of Chemistry and Biochemistry UCSC 1156 High Street Santa Cruz CA USA
| | - Alejandro R. Foley
- Dept. of Chemistry and Biochemistry UCSC 1156 High Street Santa Cruz CA USA
| | | | - Xiaolin Zhang
- Dept. of Electrical Engineering UCSC 1156 High Street Santa Cruz CA USA
- Dept. of Materials Science and Engineering University of Washington Seattle WA USA
| | - Marco Rolandi
- Dept. of Electrical Engineering UCSC 1156 High Street Santa Cruz CA USA
| | - Benjamin Abrams
- Dept. of Biomolecular Engineering Life Sciences Microscopy Center UCSC 1156 High Street Santa Cruz 95064 CA USA
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19
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Dutta S, Foley AR, Warner CJA, Zhang X, Rolandi M, Abrams B, Raskatov JA. Suppression of Oligomer Formation and Formation of Non-Toxic Fibrils upon Addition of Mirror-Image Aβ42 to the Natural l-Enantiomer. Angew Chem Int Ed Engl 2017; 56:11506-11510. [PMID: 28682473 DOI: 10.1002/anie.201706279] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Indexed: 11/11/2022]
Abstract
Racemates often have lower solubility than enantiopure compounds, and the mixing of enantiomers can enhance the aggregation propensity of peptides. Amyloid beta (Aβ) 42 is an aggregation-prone peptide that is believed to play a key role in Alzheimer's disease. Soluble Aβ42 aggregation intermediates (oligomers) have emerged as being particularly neurotoxic. We hypothesized that the addition of mirror-image d-Aβ42 should reduce the concentration of toxic oligomers formed from natural l-Aβ42. We synthesized l- and D-Aβ42 and found their equimolar mixing to lead to accelerated fibril formation. Confocal microscopy with fluorescently labeled analogues of the enantiomers showed their colocalization in racemic fibrils. Owing to the enhanced fibril formation propensity, racemic Aβ42 was less prone to form soluble oligomers. This resulted in the protection of cells from the toxicity of l-Aβ42 at concentrations up to 50 μm. The mixing of Aβ42 enantiomers thus accelerates the formation of non-toxic fibrils.
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Affiliation(s)
- Subrata Dutta
- Dept. of Chemistry and Biochemistry, UCSC, 1156 High Street, Santa Cruz, CA, USA
| | - Alejandro R Foley
- Dept. of Chemistry and Biochemistry, UCSC, 1156 High Street, Santa Cruz, CA, USA
| | | | - Xiaolin Zhang
- Dept. of Electrical Engineering, UCSC, 1156 High Street, Santa Cruz, CA, USA.,Dept. of Materials Science and Engineering, University of Washington, Seattle, WA, USA
| | - Marco Rolandi
- Dept. of Electrical Engineering, UCSC, 1156 High Street, Santa Cruz, CA, USA
| | - Benjamin Abrams
- Dept. of Biomolecular Engineering, Life Sciences Microscopy Center, UCSC, 1156 High Street, Santa Cruz, 95064, CA, USA
| | - Jevgenij A Raskatov
- Dept. of Chemistry and Biochemistry, UCSC, 1156 High Street, Santa Cruz, CA, USA
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20
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Ma LY, Lv YL, Huo K, Liu J, Shang SH, Fei YL, Li YB, Zhao BY, Wei M, Deng YN, Qu QM. Autophagy-lysosome dysfunction is involved in Aβ deposition in STZ-induced diabetic rats. Behav Brain Res 2016; 320:484-493. [PMID: 27773683 DOI: 10.1016/j.bbr.2016.10.031] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Revised: 10/13/2016] [Accepted: 10/19/2016] [Indexed: 11/15/2022]
Abstract
β-Amyloid (Aβ) deposition has a central role in the pathogenesis of Alzheimer disease (AD). Previous studies have indicated that as a risk factor for AD, diabetes mellitus (DM) could induce Aβ deposition in the brain, but the mechanism is not fully elucidated. Autophagy-lysosome is a cellular pathway involved in protein and organelle degradation. In the present study, we used streptozotocin (STZ)-induced diabetic rats to investigate whether autophagy-lysosome is related to Aβ1-42 clearance in DM. We found that DM rats had a longer escape latency and less frequent entry into the target zone than that of the control group (p<0.05) in the Morris water maze test. Meanwhile, hippocampal neuron damage and apoptosis (p<0.05) were found in the DM rats. The Aβ1-42 expression in the hippocampus significantly increased in the DM group compared with the control group (p<0.05). The markers of autophagy, beclin-1 and LC3 II, were increased (p<0.05), whereas LC3 I was decreased (p<0.05), and the ratio of LC3 II / I was increased as the time advanced (p<0.01). LAMP1 and LAMP2, which are the markers of lysosome function, were decreased in the hippocampus of DM rats (p<0.05). The Aβ1-42 deposition was correlated with beclin-1, LC3 II, and LC3 I positively (p<0.05), but with LAMP1 and LAMP2 negatively (p<0.05). These findings indicate that DM activated autophagy, but lysosome function was impaired. Autophagy-lysosome dysfunction may be involved in the Aβ deposition in diabetic cognitive impairment.
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Affiliation(s)
- Lou-Yan Ma
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China; The Second Department of Geriatrics, Xi'an Ninth Hospital, Xi'an, China
| | - Ya-Li Lv
- The Second Department of Geriatrics, Xi'an Ninth Hospital, Xi'an, China
| | - Kang Huo
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Jie Liu
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Su-Hang Shang
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Yu-Lang Fei
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Yan-Bo Li
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Bei-Yu Zhao
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Meng Wei
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Yong-Ning Deng
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Qiu-Min Qu
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
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21
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Jana MK, Cappai R, Ciccotosto GD. Oligomeric Amyloid-β Toxicity Can Be Inhibited by Blocking Its Cellular Binding in Cortical Neuronal Cultures with Addition of the Triphenylmethane Dye Brilliant Blue G. ACS Chem Neurosci 2016; 7:1141-7. [PMID: 27258855 DOI: 10.1021/acschemneuro.6b00108] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Accumulation of soluble amyloid β (Aβ) oligomers in the brain has been suggested to cause neurodegeneration associated with Alzheimer's disease (AD). Our previous findings showed that the binding of Aβ trimer and tetramer to neurons is significantly correlated with Aβ-induced neuronal cell death. We propose blocking of neuronal binding of these neurotoxic Aβ oligomers as a therapeutic strategy for preventing this disease. To test this, a nontoxic triphenylmethane dye, Brilliant Blue G (BBG), which has been reported to modulate Aβ aggregation and neurotoxicity, was investigated using mouse primary cortical neuronal cultures treated with photoinduced cross-linked toxic Aβ40 oligomers as well as soluble Aβ40 and Aβ42 peptides. We found that the BBG-induced decrease in Aβ binding resulted in a significant decrease in its neurotoxicity. These findings support our hypothesis that disruption of cellular Aβ binding is a promising therapeutic strategy for combating AD.
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Affiliation(s)
- Metta K. Jana
- Department of Pathology, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Roberto Cappai
- Department of Pathology, The University of Melbourne, Parkville, VIC 3010, Australia
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22
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Jana MK, Cappai R, Pham CLL, Ciccotosto GD. Membrane-bound tetramer and trimer Aβ oligomeric species correlate with toxicity towards cultured neurons. J Neurochem 2016; 136:594-608. [DOI: 10.1111/jnc.13443] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 11/11/2015] [Accepted: 11/23/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Metta K. Jana
- Department of Pathology; Bio21 Molecular Science and Biotechnology Institute; The University of Melbourne; Parkville Vic. Australia
| | - Roberto Cappai
- Department of Pathology; Bio21 Molecular Science and Biotechnology Institute; The University of Melbourne; Parkville Vic. Australia
| | - Chi L. L. Pham
- Department of Pathology; Bio21 Molecular Science and Biotechnology Institute; The University of Melbourne; Parkville Vic. Australia
| | - Giuseppe D. Ciccotosto
- Department of Pathology; Bio21 Molecular Science and Biotechnology Institute; The University of Melbourne; Parkville Vic. Australia
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23
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Jang H, Arce FT, Ramachandran S, Kagan BL, Lal R, Nussinov R. Disordered amyloidogenic peptides may insert into the membrane and assemble into common cyclic structural motifs. Chem Soc Rev 2014; 43:6750-64. [PMID: 24566672 PMCID: PMC4143503 DOI: 10.1039/c3cs60459d] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Aggregation of disordered amyloidogenic peptides into oligomers is the causative agent of amyloid-related diseases. In solution, disordered protein states are characterized by heterogeneous ensembles. Among these, β-rich conformers self-assemble via a conformational selection mechanism to form energetically-favored cross-β structures, regardless of their precise sequences. These disordered peptides can also penetrate the membrane, and electrophysiological data indicate that they form ion-conducting channels. Based on these and additional data, including imaging and molecular dynamics simulations of a range of amyloid peptides, Alzheimer's amyloid-β (Aβ) peptide, its disease-related variants with point mutations and N-terminal truncated species, other amyloidogenic peptides, as well as a cytolytic peptide and a synthetic gel-forming peptide, we suggest that disordered amyloidogenic peptides can also present a common motif in the membrane. The motif consists of curved, moon-like β-rich oligomers associated into annular organizations. The motif is favored in the lipid bilayer since it permits hydrophobic side chains to face and interact with the membrane and the charged/polar residues to face the solvated channel pores. Such channels are toxic since their pores allow uncontrolled leakage of ions into/out of the cell, destabilizing cellular ionic homeostasis. Here we detail Aβ, whose aggregation is associated with Alzheimer's disease (AD) and for which there are the most abundant data. AD is a protein misfolding disease characterized by a build-up of Aβ peptide as senile plaques, neurodegeneration, and memory loss. Excessively produced Aβ peptides may directly induce cellular toxicity, even without the involvement of membrane receptors through Aβ peptide-plasma membrane interactions.
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Affiliation(s)
- Hyunbum Jang
- Cancer and Inflammation Program, National Cancer Institute at Frederick, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, U.S.A
| | - Fernando Teran Arce
- Departments of Bioengineering and of Mechanical and Aerospace Engineering, and Materials Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Srinivasan Ramachandran
- Departments of Bioengineering and of Mechanical and Aerospace Engineering, and Materials Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Bruce L. Kagan
- Department of Psychiatry, David Geffen School of Medicine, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, California 90024, U.S.A
| | - Ratnesh Lal
- Departments of Bioengineering and of Mechanical and Aerospace Engineering, and Materials Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Ruth Nussinov
- Cancer and Inflammation Program, National Cancer Institute at Frederick, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, U.S.A
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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24
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Ciccotosto GD, James SA, Altissimo M, Paterson D, Vogt S, Lai B, de Jonge MD, Howard DL, Bush AI, Cappai R. Quantitation and localization of intracellular redox active metals by X-ray fluorescence microscopy in cortical neurons derived from APP and APLP2 knockout tissue. Metallomics 2014; 6:1894-904. [PMID: 25098278 DOI: 10.1039/c4mt00176a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The amyloid precursor protein (APP) gene family includes APP and the amyloid precursor-like proteins, APLP1 and APLP2. These proteins contain metal binding sites for copper, zinc and iron and are known to have physiological roles in modulating the metal homeostasis in brain cells. Here we report the application of X-ray fluorescence microscopy (XFM) to investigate the subcellular distribution patterns of the metal ions Cu, Zn, Fe, and Ca in individual neurons derived from APP and APLP2 knockout mice brains to further define their role in metal homeostasis. These studies add to the growing body of data that the APP family of proteins are metalloproteins that have shared as well as distinct effects on metals. As we continue to delineate the cellular effects of the APP family of proteins it is important to consider how metals are involved in their actions.
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Affiliation(s)
- Giuseppe D Ciccotosto
- Department of Pathology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia.
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25
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Jang H, Connelly L, Arce FT, Ramachandran S, Lal R, Kagan BL, Nussinov R. Alzheimer's disease: which type of amyloid-preventing drug agents to employ? Phys Chem Chem Phys 2013; 15:8868-77. [PMID: 23450150 PMCID: PMC3663909 DOI: 10.1039/c3cp00017f] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The current paradigm in the amyloid hypothesis brands small β-amyloid (Aβ) oligomers as the toxic species in Alzheimer's disease (AD). These oligomers are fibril-like; contain β-sheet structure, and present exposed hydrophobic surface. Oligomers with this motif are capable of penetrating the cell membrane, gathering to form toxic ion channels. Current agents suppressing precursor Aβ cleavage have only met partial success; and to date, those targeting the peptides and their assemblies in the aqueous environment of the extracellular space largely fail in clinical trials. One possible reason is failure to reach membrane-embedded targets of disease-'infected' cells. Here we provide an overview, point to the need to account for the lipid environment when aiming to prevent the formation of toxic channels, and propose a combination therapy to target the species spectrum.
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Affiliation(s)
- Hyunbum Jang
- Center for Cancer Research, Nanobiology Program, Basic Science Program, SAIC-Frederick, Inc., National Cancer Institute, Frederick, Maryland 21702, USA
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26
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Ryan TM, Caine J, Mertens HDT, Kirby N, Nigro J, Breheney K, Waddington LJ, Streltsov VA, Curtain C, Masters CL, Roberts BR. Ammonium hydroxide treatment of Aβ produces an aggregate free solution suitable for biophysical and cell culture characterization. PeerJ 2013; 1:e73. [PMID: 23678397 PMCID: PMC3646356 DOI: 10.7717/peerj.73] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Accepted: 04/22/2013] [Indexed: 11/20/2022] Open
Abstract
Alzheimer's disease is the leading cause of dementia in the elderly. Pathologically it is characterized by the presence of amyloid plaques and neuronal loss within the brain tissue of affected individuals. It is now widely hypothesised that fibrillar structures represent an inert structure. Biophysical and toxicity assays attempting to characterize the formation of both the fibrillar and the intermediate oligomeric structures of Aβ typically involves preparing samples which are largely monomeric; the most common method by which this is achieved is to use the fluorinated organic solvent 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). Recent evidence has suggested that this method is not 100% effective in producing an aggregate free solution. We show, using dynamic light scattering, size exclusion chromatography and small angle X-ray scattering that this is indeed the case, with HFIP pretreated Aβ peptide solutions displaying an increased proportion of oligomeric and aggregated material and an increased propensity to aggregate. Furthermore we show that an alternative technique, involving treatment with strong alkali results in a much more homogenous solution that is largely monomeric. These techniques for solubilising and controlling the oligomeric state of Aβ are valuable starting points for future biophysical and toxicity assays.
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Affiliation(s)
- Timothy M Ryan
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne , Parkville, Victoria , Australia
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27
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Kok WM, Cottam JM, Ciccotosto GD, Miles LA, Karas JA, Scanlon DB, Roberts BR, Parker MW, Cappai R, Barnham KJ, Hutton CA. Synthetic dityrosine-linked β-amyloid dimers form stable, soluble, neurotoxic oligomers. Chem Sci 2013. [DOI: 10.1039/c3sc22295k] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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28
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Ripoli C, Piacentini R, Riccardi E, Leone L, Li Puma DD, Bitan G, Grassi C. Effects of different amyloid β-protein analogues on synaptic function. Neurobiol Aging 2012; 34:1032-44. [PMID: 23046860 DOI: 10.1016/j.neurobiolaging.2012.06.027] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 05/31/2012] [Accepted: 06/03/2012] [Indexed: 10/27/2022]
Abstract
Perisynaptic accumulations of amyloid β-protein (Aβ) play a critical role in the synaptic dysfunction underlying the cognitive impairment observed in Alzheimer's disease. The methionine residue at position 35 (Met35) in Aβ is highly subject to oxidation in Alzheimer's disease brains. In hippocampal brain slices we found that long-term potentiation at CA3-CA1 synapses was significantly inhibited by wild type Aβ42 in which Met35 is reduced, but not by Aβ42 harboring Met35 sulfoxide. Similar differences were observed when basal synaptic transmission was investigated in autaptic hippocampal neurons. The significant decreases in excitatory postsynaptic current amplitude, vesicle release probability and miniature excitatory postsynaptic current frequency caused by 20-minute exposure to wild type Aβ42 were not observed after exposure to Aβ42 harboring Met35 sulfoxide. With longer (24-hour) Aβ treatments, this early impairment of the presynaptic terminal function extended to involve the postsynaptic side as well. The Met35 oxidation also affected Aβ42 negative impact on dendritic spine density and expression of pre- and postsynaptic proteins (synaptophysin and postsynaptic density protein-95). Our findings suggest that oxidation of Met35 is critical for molecular, structural, and functional determinants of Aβ42 synaptotoxicity.
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Affiliation(s)
- Cristian Ripoli
- Institute of Human Physiology, Università Cattolica, Rome, Italy
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29
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Bharadwaj P, Head R, Martins R, Raussens V, Sarroukh R, Jegasothy H, Waddington L, Bennett L. Modulation of amyloid-β 1-42 structure and toxicity by proline-rich whey peptides. Food Funct 2012; 4:92-103. [PMID: 23014463 DOI: 10.1039/c2fo30111c] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A proline-rich peptide product prepared from bovine whey protein that was enriched in several hydrophobic amino acids including proline (whey proline-rich peptide, wPRP) was shown to modulate the folding pathway of human amyloid beta peptide 1-42 (Aβ42) into oligomers. Concentration-dependent changes in ThT-binding to Ab42 by wPRP indicated suppression of oligomerisation, that was supported by Transmission Electron Microscopy. Suppression of β-sheet and specifically, anti-parallel β-sheet structures by wPRP was demonstrated by ATR-FTIR spectroscopy, where evidence for capacity of wPRP to dissociate pre-existing β-sheet structures in Aβ42 was also apparent. Suppression of anti-parallel β-sheets of oligomeric Aβ42 was associated with rescue of yeast and SH-SY5Y neuronal cells providing important evidence for the association between anti-parallel β-sheet structure and oligomer toxicity. It was proposed that the interaction of wPRP with Aβ42 interfered with the anti-parallel folding pathway of oligomeric Aβ42 and ultimately produced 'off-pathway' structures of lowered total β-sheet content, with attenuated cellular toxicity.
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Affiliation(s)
- Prashant Bharadwaj
- CSIRO Preventative Health Flagship, Material Science and Engineering, 343 Royal Parade, Parkville, Victoria 3052, Australia
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Eskici G, Axelsen PH. Copper and Oxidative Stress in the Pathogenesis of Alzheimer’s Disease. Biochemistry 2012; 51:6289-311. [DOI: 10.1021/bi3006169] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Gözde Eskici
- Departments of Pharmacology, Biochemistry and Biophysics,
and Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United
States
| | - Paul H. Axelsen
- Departments of Pharmacology, Biochemistry and Biophysics,
and Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United
States
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31
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Masters CL, Selkoe DJ. Biochemistry of amyloid β-protein and amyloid deposits in Alzheimer disease. Cold Spring Harb Perspect Med 2012; 2:a006262. [PMID: 22675658 PMCID: PMC3367542 DOI: 10.1101/cshperspect.a006262] [Citation(s) in RCA: 395] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Progressive cerebral deposition of the amyloid β-protein (Aβ) in brain regions serving memory and cognition is an invariant and defining feature of Alzheimer disease. A highly similar but less robust process accompanies brain aging in many nondemented humans, lower primates, and some other mammals. The discovery of Aβ as the subunit of the amyloid fibrils in meningocerebral blood vessels and parenchymal plaques has led to innumerable studies of its biochemistry and potential cytotoxic properties. Here we will review the discovery of Aβ, numerous aspects of its complex biochemistry, and current attempts to understand how a range of Aβ assemblies, including soluble oligomers and insoluble fibrils, may precipitate and promote neuronal and glial alterations that underlie the development of dementia. Although the role of Aβ as a key molecular factor in the etiology of Alzheimer disease remains controversial, clinical trials of amyloid-lowering agents, reviewed elsewhere in this book, are poised to resolve the question of its pathogenic primacy.
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Affiliation(s)
- Colin L Masters
- The Mental Health Research Institute, The University of Melbourne, Parkville 3010, Australia.
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Capone R, Jang H, Kotler SA, Connelly L, Teran Arce F, Ramachandran S, Kagan BL, Nussinov R, Lal R. All-d-Enantiomer of β-Amyloid Peptide Forms Ion Channels in Lipid Bilayers. J Chem Theory Comput 2012; 8:1143-1152. [PMID: 22423218 PMCID: PMC3302213 DOI: 10.1021/ct200885r] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Indexed: 12/11/2022]
Abstract
Alzheimer's disease (AD) is the most common type of senile dementia in aging populations. Amyloid β (Aβ)-mediated dysregulation of ionic homeostasis is the prevailing underlying mechanism leading to synaptic degeneration and neuronal death. Aβ-dependent ionic dysregulation most likely occurs either directly via unregulated ionic transport through the membrane or indirectly via Aβ binding to cell membrane receptors and subsequent opening of existing ion channels or transporters. Receptor binding is expected to involve a high degree of stereospecificity. Here, we investigated whether an Aβ peptide enantiomer, whose entire sequence consists of d-amino acids, can form ion-conducting channels; these channels can directly mediate Aβ effects even in the absence of receptor-peptide interactions. Using complementary approaches of planar lipid bilayer (PLB) electrophysiological recordings and molecular dynamics (MD) simulations, we show that the d-Aβ isomer exhibits ion conductance behavior in the bilayer indistinguishable from that described earlier for the l-Aβ isomer. The d isomer forms channel-like pores with heterogeneous ionic conductance similar to the l-Aβ isomer channels, and the d-isomer channel conductance is blocked by Zn(2+), a known blocker of l-Aβ isomer channels. MD simulations further verify formation of β-barrel-like Aβ channels with d- and l-isomers, illustrating that both d- and l-Aβ barrels can conduct cations. The calculated values of the single-channel conductance are approximately in the range of the experimental values. These findings are in agreement with amyloids forming Ca(2+) leaking, unregulated channels in AD, and suggest that Aβ toxicity is mediated through a receptor-independent, nonstereoselective mechanism.
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Affiliation(s)
- Ricardo Capone
- Departments of Bioengineering
and Mechanical and Aerospace Engineering and Material Science Program, University of California—San Diego, La Jolla,
California 92093, United States
| | - Hyunbum Jang
- Center for Cancer Research Nanobiology
Program, SAIC-Frederick, Incorporated,
NCI-Frederick, Frederick, Maryland 21702, United States
| | - Samuel A. Kotler
- Departments of Bioengineering
and Mechanical and Aerospace Engineering and Material Science Program, University of California—San Diego, La Jolla,
California 92093, United States
| | - Laura Connelly
- Departments of Bioengineering
and Mechanical and Aerospace Engineering and Material Science Program, University of California—San Diego, La Jolla,
California 92093, United States
| | - Fernando Teran Arce
- Departments of Bioengineering
and Mechanical and Aerospace Engineering and Material Science Program, University of California—San Diego, La Jolla,
California 92093, United States
| | - Srinivasan Ramachandran
- Departments of Bioengineering
and Mechanical and Aerospace Engineering and Material Science Program, University of California—San Diego, La Jolla,
California 92093, United States
| | - Bruce L. Kagan
- Department of Psychiatry, David
Geffen School of Medicine, Semel Institute for Neuroscience and Human
Behavior, University of California—Los Angeles, Los Angeles, California 90024, United States
| | - Ruth Nussinov
- Center for Cancer Research Nanobiology
Program, SAIC-Frederick, Incorporated,
NCI-Frederick, Frederick, Maryland 21702, United States
- Department of Human Molecular
Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ratnesh Lal
- Departments of Bioengineering
and Mechanical and Aerospace Engineering and Material Science Program, University of California—San Diego, La Jolla,
California 92093, United States
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Connelly L, Arce FT, Jang H, Capone R, Kotler SA, Ramachandran S, Kagan BL, Nussinov R, Lal R. Atomic force microscopy and MD simulations reveal pore-like structures of all-D-enantiomer of Alzheimer's β-amyloid peptide: relevance to the ion channel mechanism of AD pathology. J Phys Chem B 2012; 116:1728-35. [PMID: 22217000 PMCID: PMC4342054 DOI: 10.1021/jp2108126] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease (AD) is a protein misfolding disease characterized by a buildup of β-amyloid (Aβ) peptide as senile plaques, uncontrolled neurodegeneration, and memory loss. AD pathology is linked to the destabilization of cellular ionic homeostasis and involves Aβ peptide-plasma membrane interactions. In principle, there are two possible ways through which disturbance of the ionic homeostasis can take place: directly, where the Aβ peptide either inserts into the membrane and creates ion-conductive pores or destabilizes the membrane organization, or, indirectly, where the Aβ peptide interacts with existing cell membrane receptors. To distinguish between these two possible types of Aβ-membrane interactions, we took advantage of the biochemical tenet that ligand-receptor interactions are stereospecific; L-amino acid peptides, but not their D-counterparts, bind to cell membrane receptors. However, with respect to the ion channel-mediated mechanism, like L-amino acids, D-amino acid peptides will also form ion channel-like structures. Using atomic force microscopy (AFM), we imaged the structures of both D- and L-enantiomers of the full length Aβ(1-42) when reconstituted in lipid bilayers. AFM imaging shows that both L- and D-Aβ isomers form similar channel-like structures. Molecular dynamics (MD) simulations support the AFM imaged 3D structures. Previously, we have shown that D-Aβ(1-42) channels conduct ions similarly to their L- counterparts. Taken together, our results support the direct mechanism of Aβ ion channel-mediated destabilization of ionic homeostasis rather than the indirect mechanism through Aβ interaction with membrane receptors.
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Affiliation(s)
- Laura Connelly
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Materials Science Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Fernando Teran Arce
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Materials Science Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Hyunbum Jang
- Center for Cancer Research Nanobiology Program, SAIC-Frederick, Inc., NCI-Frederick, Frederick, MD 21702, USA
| | - Ricardo Capone
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Materials Science Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Samuel A. Kotler
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Materials Science Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Srinivasan Ramachandran
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Materials Science Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Bruce L. Kagan
- Department of Psychiatry, David Geffen School of Medicine, Semel Institute for Neuroscience Human Behavior, University of California, Los Angeles, CA 90024, USA
| | - Ruth Nussinov
- Center for Cancer Research Nanobiology Program, SAIC-Frederick, Inc., NCI-Frederick, Frederick, MD 21702, USA
| | - Ratnesh Lal
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Materials Science Program, University of California, San Diego, La Jolla, CA 92093, USA
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Correia SC, Santos RX, Carvalho C, Cardoso S, Candeias E, Santos MS, Oliveira CR, Moreira PI. Insulin signaling, glucose metabolism and mitochondria: major players in Alzheimer's disease and diabetes interrelation. Brain Res 2012; 1441:64-78. [PMID: 22290178 DOI: 10.1016/j.brainres.2011.12.063] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2011] [Revised: 11/07/2011] [Accepted: 12/31/2011] [Indexed: 12/24/2022]
Abstract
Many epidemiological studies have shown that diabetes, particularly type 2 diabetes, significantly increases the risk to develop Alzheimer's disease. Both diseases share several common abnormalities including impaired glucose metabolism, increased oxidative stress, insulin resistance and deposition of amyloidogenic proteins. It has been suggested that these two diseases disrupt common cellular and molecular pathways and each disease potentiates the progression of the other. This review discusses clinical and biochemical features shared by Alzheimer's disease and diabetes, giving special attention to the involvement of insulin signaling, glucose metabolism and mitochondria. Understanding the key mechanisms underlying this deleterious interaction may provide opportunities for the design of effective therapeutic strategies.
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Affiliation(s)
- Sónia C Correia
- Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra, Portugal
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Weber DK, Gehman JD, Separovic F, Sani MA. Copper Modulation of Amyloid Beta 42 Interactions with Model Membranes. Aust J Chem 2012. [DOI: 10.1071/ch12015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Growing evidence supports that interactions of the amyloid-β peptide Aβ(1–42) with neuronal cell membranes and copper are involved in Alzheimer’s disease pathogenesis. We report using solid-state NMR that the peptide significantly perturbed the phosphate and upper acyl chain region of bilayers comprising brain total lipid extract to cause domain segregation. Deep headgroup perturbations were also realized for palmitoyloleoylphospatidylcholine–cholesterol model systems; however, incorporating 10 % palmitoyloleoylphosphatidylserine or the ganglioside GM1 resulted in a more peripheral interaction. Cu2+ at a 1 : 7 molar ratio to peptide caused deeper penetration into model systems, but partially attenuated interactions with brain total lipid extract. Thioflavin T assay showed that bilayers affected amyloid formation in a mode dependant on lipid content, and was further modulated by addition of Cu2+. Our data support that ternary interactions between Cu2+, lipids and Aβ(1–42) may have significance in Alzheimer’s disease, and challenge the validity of model bilayers as substitutes for natural systems.
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Krištofiková Z, Kříž Z, Řípová D, Koča J. Interactions of Amyloid β Peptide 1–40 and Cerebrosterol. Neurochem Res 2011; 37:604-13. [DOI: 10.1007/s11064-011-0650-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 10/31/2011] [Accepted: 11/03/2011] [Indexed: 01/07/2023]
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Salazar-Weber NL, Smith JP. Copper Inhibits NMDA Receptor-Independent LTP and Modulates the Paired-Pulse Ratio after LTP in Mouse Hippocampal Slices. Int J Alzheimers Dis 2011; 2011:864753. [PMID: 22028985 PMCID: PMC3199118 DOI: 10.4061/2011/864753] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 08/05/2011] [Accepted: 08/16/2011] [Indexed: 11/20/2022] Open
Abstract
Copper misregulation has been implicated in the pathological processes underlying deterioration of learning and memory in Alzheimer's disease and other neurodegenerative disorders. Supporting this, inhibition of long-term potentiation (LTP) by copper (II) has been well established, but the exact mechanism is poorly characterized. It is thought that an interaction between copper and postsynaptic NMDA receptors is a major part of the mechanism; however, in this study, we found that copper (II) inhibited NMDA receptor-independent LTP in the CA3 region of hippocampal slices. In addition, in the CA3 and CA1 regions, copper modulated the paired-pulse ratio (PPR) in an LTP-dependent manner. Combined, this suggests the involvement of a presynaptic mechanism in the modulation of synaptic plasticity by copper. Inhibition of the copper-dependent changes in the PPR with cyclothiazide suggested that this may involve an interaction with the presynaptic AMPA receptors that regulate neurotransmitter release.
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Affiliation(s)
- Nina L Salazar-Weber
- Department of Biology, Colorado State University-Pueblo, 2200 Bonforte Boulevard, Pueblo, CO 81001, USA
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Neniskyte U, Neher JJ, Brown GC. Neuronal death induced by nanomolar amyloid β is mediated by primary phagocytosis of neurons by microglia. J Biol Chem 2011; 286:39904-13. [PMID: 21903584 PMCID: PMC3220594 DOI: 10.1074/jbc.m111.267583] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Alzheimer disease is characterized by neuronal loss and brain plaques of extracellular amyloid β (Aβ), but the means by which Aβ may induce neuronal loss is not entirely clear. Although high concentrations of Aβ (μm) can induce direct toxicity to neurons, we find that low concentration (nm) induce neuronal loss through a microglia-mediated mechanism. In mixed neuronal-glial cultures from rat cerebellum, 250 nm Aβ1–42 (added as monomers, oligomers or fibers) induced about 30% loss of neurons between 2 and 3 days. This neuronal loss occurred without any increase in neuronal apoptosis or necrosis, and no neuronal loss occurred with Aβ42–1. Aβ greatly increased the phagocytic capacity of microglia and induced phosphatidylserine exposure (an “eat-me” signal) on neuronal processes. Blocking exposed phosphatidylserine by adding annexin V or an antibody to phosphatidylserine or inhibiting microglial phagocytosis by adding either cytochalasin D (to block actin polymerization) or cyclo(RGDfV) (to block vitronectin receptors) significantly prevented neuronal loss. Loss of neuronal synapses occurred in parallel with loss of cell bodies and was also prevented by blocking phagocytosis. Inhibition of phagocytosis prevented neuronal loss with no increase in neuronal death, even after 7 days, suggesting that microglial phagocytosis was the primary cause of neuronal death induced by nanomolar Aβ.
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Affiliation(s)
- Urte Neniskyte
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom.
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Alleviating transcriptional inhibition of the norepinephrine slc6a2 transporter gene in depolarized neurons. J Neurosci 2010; 30:1494-501. [PMID: 20107077 DOI: 10.1523/jneurosci.4675-09.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Recent studies have brought to light additional experimental information, namely, that the MeCP2 protein complex is not only capable of associating with members of the ATPase-dependent bromodomain family, but also found on nonmethylated genomic sequences. These unexpected results are indicative of a multifunctional role for MeCP2, more importantly; our view of the molecular mechanisms that regulate gene activity may not be necessarily distinguishable. Depolarized mouse neuronal cortical cells were examined for increased Slc6a2 mRNA synthesis, changes in CpG methylation status using bisulfite sequencing, and binding of MeCP2 and Smarca2 on the Slc6a2 promoter sequence by chromatin immunopurification strategies. Increased Slc6a2 gene expression in response to membrane depolarization was strongly correlated with the dissociation of MeCP2 and Smarca2 complex on the unmethylated gene. We identified that gene expression in neuronal cortical cells involves increased histone hyperacetylation on the Slc6a2 promoter, which is commensurate with the recruitment of SP1 and RNA Polymerase II and is inversely correlated with H3K9 trimethylation. We hypothesize that the MeCP2 corepressor is capable of associating with multiple forms of SWI/SNF to remodel chromatin for important regulatory roles. The results of our experiments indicate that these proteins are asymmetrically bound to chromatin independent of DNA methylation and not inevitably diametrically opposed. These results now begin to offer a new perspective on the mechanism of Slc6a2 gene regulation.
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Poduslo JF, Gilles EJ, Ramakrishnan M, Howell KG, Wengenack TM, Curran GL, Kandimalla KK. HH domain of Alzheimer's disease Abeta provides structural basis for neuronal binding in PC12 and mouse cortical/hippocampal neurons. PLoS One 2010; 5:e8813. [PMID: 20098681 PMCID: PMC2809098 DOI: 10.1371/journal.pone.0008813] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Accepted: 12/22/2009] [Indexed: 11/18/2022] Open
Abstract
A key question in understanding AD is whether extracellular Aβ deposition of parenchymal amyloid plaques or intraneuronal Aβ accumulation initiates the AD process. Amyloid precursor protein (APP) is endocytosed from the cell surface into endosomes where it is cleaved to produce soluble Aβ which is then released into the brain interstitial fluid. Intraneuronal Aβ accumulation is hypothesized to predominate from the neuronal uptake of this soluble extracellular Aβ rather than from ER/Golgi processing of APP. We demonstrate that substitution of the two adjacent histidine residues of Aβ40 results in a significant decrease in its binding with PC12 cells and mouse cortical/hippocampal neurons. These substitutions also result in a dramatic enhancement of both thioflavin-T positive fibril formation and binding to preformed Aβ fibrils while maintaining its plaque-binding ability in AD transgenic mice. Hence, alteration of the histidine domain of Aβ prevented neuronal binding and drove Aβ to enhanced fibril formation and subsequent amyloid plaque deposition - a potential mechanism for removing toxic species of Aβ. Substitution or even masking of these Aβ histidine residues might provide a new therapeutic direction for minimizing neuronal uptake and subsequent neuronal degeneration and maximizing targeting to amyloid plaques.
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Affiliation(s)
- Joseph F Poduslo
- Molecular Neurobiology Laboratory, Department of Neurology, Mayo Clinic College of Medicine, Rochester, Minnesota, United States of America.
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Ondrejcak T, Klyubin I, Hu NW, Barry AE, Cullen WK, Rowan MJ. Alzheimer's disease amyloid beta-protein and synaptic function. Neuromolecular Med 2009; 12:13-26. [PMID: 19757208 DOI: 10.1007/s12017-009-8091-0] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Accepted: 08/25/2009] [Indexed: 12/15/2022]
Abstract
Alzheimer's disease (AD) is characterized neuropathologically by the deposition of different forms of amyloid beta-protein (A beta) including variable amounts of soluble species that correlate with severity of dementia. The extent of synaptic loss in the brain provides the best morphological correlate of cognitive impairment in clinical AD. Animal research on the pathophysiology of AD has therefore focussed on how soluble A beta disrupts synaptic mechanisms in vulnerable brain regions such as the hippocampus. Synaptic plasticity in the form of persistent activity-dependent increases or decreases in synaptic strength provide a neurophysiological substrate for hippocampal-dependent learning and memory. Acute treatment with human-derived or chemically prepared soluble A beta that contains certain oligomeric assemblies, potently and selectively disrupts synaptic plasticity causing inhibition of long-term potentiation (LTP) and enhancement of long-term depression (LTD) of glutamatergic transmission. Over time these and related actions of A beta have been implicated in reducing synaptic integrity. This review addresses the involvement of neurotransmitter intercellular signaling in mediating or modulating the synaptic plasticity disrupting actions of soluble A beta, with particular emphasis on the different roles of glutamatergic and cholinergic mechanisms. There is growing evidence to support the view that NMDA and possibly nicotinic receptors are critically involved in mediating the disruptive effect of A beta and that targeting muscarinic receptors can indirectly modulate A beta's actions. Such studies should help inform ongoing and future clinical trials of drugs acting through the glutamatergic and cholinergic systems.
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Affiliation(s)
- Tomas Ondrejcak
- Department of Pharmacology and Therapeutics, Biotechnology Building and Institute of Neuroscience, Trinity College, Dublin 2, Ireland
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