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Xu Y, Filice CT, Leonenko Z. Protective effect of trehalose sugar on amyloid-membrane interactions using BLM electrophysiology. Biophys J 2024; 123:1690-1704. [PMID: 38751113 PMCID: PMC11213996 DOI: 10.1016/j.bpj.2024.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 04/10/2024] [Accepted: 05/13/2024] [Indexed: 05/30/2024] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease characterized by dementia and memory loss in the elderly population. The amyloid-β peptide (Aβ) is one of the main pathogenic factors in AD and is known to cause damage to neuronal cellular membranes. There is no cure currently available for AD, and new approaches, including preventive strategies, are highly desirable. In this work, we explore the possibility of protecting neuronal membranes from amyloid-induced damage with naturally existing sugar trehalose. Trehalose has been shown to protect plant cellular membranes in extreme conditions and modify Aβ misfolding. We hypothesize that trehalose can protect the neuronal membrane from amyloid toxicity. In this work, we studied the protective effect of trehalose against Aβ1-42-induced damage in model lipid membranes (DPPC/POPC/cholesterol) using atomic force microscopy and black lipid membrane electrophysiology. Our results demonstrate that Aβ1-42 damaged membranes and led to ionic current leakage across these membranes due to the formation of various defects and pores. The presence of trehalose reduced the ion current across membranes caused by Aβ1-42 peptide damage, thus efficiently protecting the membranes. These findings suggest that the trehalose sugar can potentially be useful in protecting neuronal membranes against amyloid toxicity in AD.
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Affiliation(s)
- Yue Xu
- Department of Physics & Astronomy, University of Waterloo, Waterloo, ON, Canada
| | - Carina Teresa Filice
- Department of Biology, University of Waterloo, Waterloo, ON, Canada; Waterloo Institute for Nanotechnology, Waterloo, ON, Canada
| | - Zoya Leonenko
- Department of Physics & Astronomy, University of Waterloo, Waterloo, ON, Canada; Department of Biology, University of Waterloo, Waterloo, ON, Canada; Waterloo Institute for Nanotechnology, Waterloo, ON, Canada.
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2
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Ritwiset A, Maensiri S, Krongsuk S. Insight into molecular structures and dynamical properties of niosome bilayers containing melatonin molecules: a molecular dynamics simulation approach. RSC Adv 2024; 14:1697-1709. [PMID: 38187447 PMCID: PMC10768803 DOI: 10.1039/d3ra07564h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 12/26/2023] [Indexed: 01/09/2024] Open
Abstract
Niosomes represent vesicular carriers capable of encapsulating both hydrophobic and hydrophilic drugs within their inner core or bilayer shell. They are typically composed of non-ionic synthetic surfactants such as sorbitan monostearate (Span60) with the addition of cholesterol (Chol). The physical properties and stability of niosomal vesicles strongly depend on the composition of their bilayers, which plays a significant role in determining the efficiency of drug encapsulation and release in drug delivery systems. In this study, we have explored the interactions between melatonin (Mel) molecules and the niosome bilayer, as well as their resulting physical properties. Molecular dynamics simulations were employed to investigate melatonin-inserted niosome bilayers, both with and without the inclusion of cholesterol. The simulation results revealed that cholesterol notably influences the location of melatonin molecules within the niosome bilayers. In the absence of cholesterol, melatonin tends to occupy the region around the Span60 tail groups. However, in the presence of cholesterol, melatonin is found in the vicinity of the Span60 head groups. Melatonin molecules in niosome bilayers without cholesterol exhibit a more ordered orientation when compared to those in bilayers containing 50 mol% cholesterol. The bilayer structure of the Span60/Mel and Span60/Chol/Mel systems exhibited a liquid-disordered phase (Ld). In contrast, the Span60/Chol bilayer system displays a liquid-ordered phase (Lo) with less fluidity. This study reveals that melatonin induces a disorderly bilayer structure and greater lateral expansion, whereas cholesterol induces an orderly bilayer structure and a more condensed effect. Cholesterol plays a crucial role in condensing the bilayer structure with stronger interactions between Span60 and cholesterol. The addition of 50 mol% cholesterol in the Span60 bilayers not only enhances the stability and rigidity of niosomes but also facilitates the easier release of melatonin from the bilayer membranes. This finding is particularly valuable in the context of preparing niosomes for drug delivery systems.
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Affiliation(s)
- Aksornnarong Ritwiset
- School of Physics, Institute of Science, Suranaree University of Technology Nakhon Ratchasima 30000 Thailand
| | - Santi Maensiri
- School of Physics, Institute of Science, Suranaree University of Technology Nakhon Ratchasima 30000 Thailand
- Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology Nakhon Ratchasima 30000 Thailand
| | - Sriprajak Krongsuk
- Department of Physics, Faculty of Science, Khon Kaen University Khon Kaen 40002 Thailand
- Institute of Nanomaterials Research and Innovation for Energy (IN-RIE), Khon Kaen University Khon Kaen 40002 Thailand
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3
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Kurakin S, Badreeva D, Dushanov E, Shutikov A, Efimov S, Timerova A, Mukhametzyanov T, Murugova T, Ivankov O, Mamatkulov K, Arzumanyan G, Klochkov V, Kučerka N. Arrangement of lipid vesicles and bicelle-like structures formed in the presence of Aβ(25-35) peptide. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184237. [PMID: 37820938 DOI: 10.1016/j.bbamem.2023.184237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 08/31/2023] [Accepted: 10/03/2023] [Indexed: 10/13/2023]
Abstract
Our complementary experimental data and molecular dynamics (MD) simulations results reveal the structure of previously observed lipid bicelle-like structures (BLSs) formed in the presence of amyloid-beta peptide Aβ(25-35) below the main phase transition temperature (Tm) of saturated phosphatidylcholine lipids and small unilamellar vesicles (SUVs) above this temperature. First, we show by using solid-state 31P nuclear magnetic resonance (NMR) spectroscopy that our BLSs being in the lipid gel phase demonstrate magnetic alignment along the magnetic field of NMR spectrometer and undergo a transition to SUVs in the lipid fluid phase when heated through the Tm. Secondly, thanks to the BLS alignment we present their lipid structure. Lipids are found located not only in the flat bilayered part but also around its perimeter, which is corroborated by the results of coarse-grained (CG) MD simulations. Finally, peptides appear to mix randomly with lipids in SUVs while assuming predominantly unordered secondary structures revealed by circular dichroism (CD), Raman spectroscopy, and all-atom MD simulations. Importantly, the former is changing little when the system undergoes morphological transitions between BLSs and SUVs. Our structural results then offer a platform for studying and understanding mechanisms of morphological transformations caused by the disruptive effect of amyloid-beta peptides on the lipid bilayer.
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Affiliation(s)
- Sergei Kurakin
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia; Institute of Physics, Kazan Federal University, Kremlevskaya 18, Kazan 420008, Russia.
| | - Dina Badreeva
- Meshcheryakov Laboratory of Information Technologies, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia
| | - Ermuhammad Dushanov
- Laboratory of Radiation Biology, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia
| | - Artyom Shutikov
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia
| | - Sergey Efimov
- Institute of Physics, Kazan Federal University, Kremlevskaya 18, Kazan 420008, Russia
| | - Ayzira Timerova
- Institute of Physics, Kazan Federal University, Kremlevskaya 18, Kazan 420008, Russia
| | - Timur Mukhametzyanov
- Butlerov Chemistry Institute, Kazan Federal University, Kremlevskaya 18, Kazan 420008, Russia
| | - Tatiana Murugova
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia
| | - Oleksandr Ivankov
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia
| | - Kahramon Mamatkulov
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia
| | - Grigory Arzumanyan
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia
| | - Vladimir Klochkov
- Institute of Physics, Kazan Federal University, Kremlevskaya 18, Kazan 420008, Russia
| | - Norbert Kučerka
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia; Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, Odbojárov 10, Bratislava 832 32, Slovakia.
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4
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Ivankov O, Kondela T, Dushanov EB, Ermakova EV, Murugova TN, Soloviov D, Kuklin AI, Kučerka N. Cholesterol and melatonin regulated membrane fluidity does not affect the membrane breakage triggered by amyloid-beta peptide. Biophys Chem 2023; 298:107023. [PMID: 37148823 DOI: 10.1016/j.bpc.2023.107023] [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: 01/01/2023] [Revised: 04/12/2023] [Accepted: 04/12/2023] [Indexed: 05/08/2023]
Abstract
We have studied by means of small angle neutron scattering and diffraction, and molecular dynamics simulations the effect of lipid membrane fluidity on the amyloid-beta peptide interactions with the membrane. These interactions have been discovered previously to trigger the reorganization of model membranes between unilamellar vesicles and planar membranes (bicelle-like structures) during the lipid phase transition. The morphology changes were taking place in rigid membranes prepared of fully saturated lipids and were proposed to play a role in the onset of amyloid related disorders. We show in this study that the replacement of fully saturated lipids by more fluid mono-unsaturated lipids eliminates the mentioned morphology changes, most likely due to the absence of phase transition within the temperature range investigated. We have therefore controlled the membrane rigidity also while ensuring the presence of membrane phase transition within the biologically relevant temperatures. It was done by the addition of melatonin and/or cholesterol to the initial membranes made of saturated lipids. Small angle neutron scattering experiments performed over a range of cholesterol and melatonin concentrations show their distinctive effects on the local membrane structure only. The cholesterol for example affects the membrane curvature such that spontaneously formed unilamellar vesicles are of much larger sizes than those formed by the neat lipid membranes or membranes with melatonin added. The temperature dependent experiments, however, reveal no influence on the previously discovered membrane breakage whether cholesterol or melatonin have been added.
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Affiliation(s)
- O Ivankov
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna 141980, Russia.
| | - T Kondela
- Department of Nuclear Physics and Biophysics, Faculty of Mathematics, Physics and Informatics, Comenius University Bratislava, Bratislava 842 48, Slovakia
| | - E B Dushanov
- Laboratory of Radiation Biology, Joint Institute for Nuclear Research, Dubna 141980, Russia
| | - E V Ermakova
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna 141980, Russia
| | - T N Murugova
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna 141980, Russia
| | - D Soloviov
- European Molecular Biology Laboratory (EMBL), Hamburg Outstation c/o DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - A I Kuklin
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna 141980, Russia; Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
| | - N Kučerka
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna 141980, Russia; Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, Bratislava SK-832 32, Slovakia.
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5
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Yuan R, Huang H. Anchoring of Amyloid-β onto Polyunsaturated Phospholipid Membranes. J Biomol Struct Dyn 2023; 41:1098-1108. [PMID: 34915817 DOI: 10.1080/07391102.2021.2016488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The interaction between the toxic amyloid-β and phospholipid membranes in the early stage of Alzheimer's disease is complicated and depends on many factors. It was found that polyunsaturated fatty acids affect the incidence of Alzheimer's disease. The number of double bonds in the phospholipid layer may play an important role in the molecular dynamic behavior of amyloid-β on cell membranes. In the present paper, the interactions between Aβ(25-35) and each of four phospholipids, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1-stearoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (SAPC), 1-stearoyl-2-docosahexaenooyl-sn-glycero-3-phosphocholine (SDPC), and 1,2-diarachidonoyl-sn-glycero-3-phosphocholine (DAPC), are investigated by using all-atom molecular dynamics simulation. It is interesting that, as the number of double bonds in the membrane increases, the peptide fragment prefers to stay in the surface region of the membrane rather than penetrates deeply into the membrane. With the increasing number of double bonds, the interaction between Aβ(25-35) and the membrane surface becomes stronger, especially for the interaction between the residue 28 (LYS28) in Aβ(25-35) and the phospholipids, anchoring Aβ(25-35) onto the membrane. The double bonds in phospholipid determine not only the adsorption of the peptide fragment Aβ(25-35) but also its conformation, which will influence further aggregation of Aβ in later stages.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Ruikang Yuan
- Laboratory of Soft Matter, South China University of Technology, Guangzhou, China
| | - Haohao Huang
- Laboratory of Soft Matter, South China University of Technology, Guangzhou, China
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6
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Khayat E, Delfing BM, Laracuente X, Olson A, Lockhart C, Klimov DK. Lysine Acetylation Changes the Mechanism of Aβ25-35 Peptide Binding and Dimerization in the DMPC Bilayer. ACS Chem Neurosci 2023; 14:494-505. [PMID: 36656569 DOI: 10.1021/acschemneuro.2c00722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The impact of Lys28 acetylation on Alzheimer's Aβ peptide binding to the lipid bilayer has not been previously studied, either experimentally or computationally. To probe this common post-translational modification, we performed all-atom replica exchange molecular dynamics simulations targeting binding and aggregation of acetylated acAβ25-35 peptide within the DMPC bilayer. Using the unmodified Aβ25-35 studied previously as a reference, our results can be summarized as follows. First, Lys28 acetylation strengthens the Aβ25-35 hydrophobic moment and consequently promotes the helical structure across the peptide extending it into the N-terminus. Second, because Lys28 acetylation disrupts electrostatic contact between Lys28 and lipid phosphate groups, it reduces the binding affinity of acAβ25-35 peptides to the DMPC bilayer. Accordingly, although acetylation preserves the bimodal binding featuring a preferred inserted state and a less probable surface bound state, it decreases the stability of the former. Third, acetylation promotes acAβ25-35 aggregation and eliminates monomers as thermodynamically viable species. More importantly, acAβ25-35 retains as the most thermodynamically stable the inserted dimer with unique head-to-tail helical aggregation interface. However, due to enhanced helix structure, this dimer state becomes less stable and is less likely to propagate into higher order aggregates. Thus, acetylation is predicted to facilitate the formation of low-molecular-weight oligomers. Other post-translational modifications, including phosphorylation and oxidation, reduce helical propensity and have divergent impact on aggregation. Consequently, acetylation, when considered in its totality, has distinct consequences on Aβ25-35 binding and aggregation in the lipid bilayer.
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Affiliation(s)
- Elias Khayat
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Bryan M Delfing
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Xavier Laracuente
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Audrey Olson
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Christopher Lockhart
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Dmitri K Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
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7
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Burrelli A, Moretti P, Gerelli Y, Ortore MG. Effects of model membranes on lysozyme amyloid aggregation. Biomol Concepts 2023; 14:bmc-2022-0034. [PMID: 37542518 DOI: 10.1515/bmc-2022-0034] [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: 04/30/2023] [Accepted: 07/13/2023] [Indexed: 08/07/2023] Open
Abstract
The study of the interaction between lipid membranes and amyloidogenic peptides is a turning point for understanding the processes involving the cytotoxicity of peptides involved in neurodegenerative diseases. In this work, we perform an experimental study of model membrane-lysozyme interaction to understand how the formation of amyloid fibrils can be affected by the presence of polar and zwitterionic phospholipid molecules (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine [POPC] and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol [POPG]). The study was conducted above and below the critical micellar concentration (CMC) using dynamic light scattering (DLS), atomic force microscopy (AFM), UV-Vis spectrophotometry, and the quartz crystal microbalance (QCM). Our results show that the presence of phospholipids appears to be a factor favoring the formation of amyloid aggregates. Spectrophotometric and DLS data revealed that the quantity of β -structure increases in the presence of POPG and POPC at different concentrations. The presence of POPG and POPC increases the speed of the nucleation process, without altering the overall structures of the fibrillar final products.
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Affiliation(s)
- Annaclaudia Burrelli
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Paolo Moretti
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Yuri Gerelli
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
- CNR Institute for Complex Systems, Piazzale Aldo Moro 5, 00185 Roma, Italy
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Maria Grazia Ortore
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
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Vergilio J, Lockhart C, Klimov DK. De Novo Transmembrane Aggregation of Aβ10-40 Peptides in an Anionic Lipid Bilayer. J Chem Inf Model 2022; 62:6228-6241. [PMID: 36455155 DOI: 10.1021/acs.jcim.2c01192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Using the all-atom model and 10 μs serial replica-exchange molecular dynamics (SREMD), we investigated the binding of Alzheimer's Aβ10-40 peptides to the anionic dimyristoylphosphatidylcholine/dimyristoylphosphatidylglycerol (DMPC/DMPG) lipid bilayer. Our objective was to probe de novo transmembrane Aβ10-40 aggregation and to test the utility of SREMD. Our results are threefold. First, upon binding, Aβ10-40 adopts a helical structure in the C-terminus and deeply inserts into the bilayer. Binding is primarily controlled by electrostatic interactions of the peptides with water, ions, and lipids, particularly, anionic DMPG. Second, Aβ-bilayer interactions reorganize lipids in the proximity of the bound peptides, causing an influx of DMPG lipids into the Aβ binding footprint. Third and most important, computed free energy landscapes reveal that Aβ10-40 peptides partition into monomeric and dimeric species. The dimers result from transmembrane aggregation of the peptides and induce a striking lipid density void throughout both leaflets in the bilayer. There are multiple factors stabilizing transmembrane dimers, including van der Waals and steric interactions, electrostatic interactions, and hydrogen bonding, hydration, and entropic gains originating from dimer conformations and lipid disorder. We argue that helix dipole-dipole interactions underestimated in the all-atom force field must be a contributing factor to stabilizing antiparallel transmembrane dimers. We propose that transmembrane aggregates serve as mechanistic links between the populations of extra- and intracellular Aβ peptides. From the computational perspective, SREMD is found to be a viable alternative to traditional replica-exchange simulations.
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Affiliation(s)
- James Vergilio
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Christopher Lockhart
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Dmitri K Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
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Rudajev V, Novotny J. Cholesterol as a key player in amyloid β-mediated toxicity in Alzheimer’s disease. Front Mol Neurosci 2022; 15:937056. [PMID: 36090253 PMCID: PMC9453481 DOI: 10.3389/fnmol.2022.937056] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 07/27/2022] [Indexed: 11/13/2022] Open
Abstract
Alzheimer’s disease (AD) is a neurodegenerative disorder that is one of the most devastating and widespread diseases worldwide, mainly affecting the aging population. One of the key factors contributing to AD-related neurotoxicity is the production and aggregation of amyloid β (Aβ). Many studies have shown the ability of Aβ to bind to the cell membrane and disrupt its structure, leading to cell death. Because amyloid damage affects different parts of the brain differently, it seems likely that not only Aβ but also the nature of the membrane interface with which the amyloid interacts, helps determine the final neurotoxic effect. Because cholesterol is the dominant component of the plasma membrane, it plays an important role in Aβ-induced toxicity. Elevated cholesterol levels and their regulation by statins have been shown to be important factors influencing the progression of neurodegeneration. However, data from many studies have shown that cholesterol has both neuroprotective and aggravating effects in relation to the development of AD. In this review, we attempt to summarize recent findings on the role of cholesterol in Aβ toxicity mediated by membrane binding in the pathogenesis of AD and to consider it in the broader context of the lipid composition of cell membranes.
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Santhosh PB, Genova J, Slavkova Z, Chamati H. Influence of melatonin on the structural and thermal properties of SOPC lipid membranes. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.129081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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11
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Lipid membrane-mediated assembly of the functional amyloid-forming peptide Somatostatin-14. Biophys Chem 2022; 287:106830. [DOI: 10.1016/j.bpc.2022.106830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 05/03/2022] [Accepted: 05/17/2022] [Indexed: 11/20/2022]
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Loh D, Reiter RJ. Melatonin: Regulation of Prion Protein Phase Separation in Cancer Multidrug Resistance. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27030705. [PMID: 35163973 PMCID: PMC8839844 DOI: 10.3390/molecules27030705] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/11/2022] [Accepted: 01/17/2022] [Indexed: 12/13/2022]
Abstract
The unique ability to adapt and thrive in inhospitable, stressful tumor microenvironments (TME) also renders cancer cells resistant to traditional chemotherapeutic treatments and/or novel pharmaceuticals. Cancer cells exhibit extensive metabolic alterations involving hypoxia, accelerated glycolysis, oxidative stress, and increased extracellular ATP that may activate ancient, conserved prion adaptive response strategies that exacerbate multidrug resistance (MDR) by exploiting cellular stress to increase cancer metastatic potential and stemness, balance proliferation and differentiation, and amplify resistance to apoptosis. The regulation of prions in MDR is further complicated by important, putative physiological functions of ligand-binding and signal transduction. Melatonin is capable of both enhancing physiological functions and inhibiting oncogenic properties of prion proteins. Through regulation of phase separation of the prion N-terminal domain which targets and interacts with lipid rafts, melatonin may prevent conformational changes that can result in aggregation and/or conversion to pathological, infectious isoforms. As a cancer therapy adjuvant, melatonin could modulate TME oxidative stress levels and hypoxia, reverse pH gradient changes, reduce lipid peroxidation, and protect lipid raft compositions to suppress prion-mediated, non-Mendelian, heritable, but often reversible epigenetic adaptations that facilitate cancer heterogeneity, stemness, metastasis, and drug resistance. This review examines some of the mechanisms that may balance physiological and pathological effects of prions and prion-like proteins achieved through the synergistic use of melatonin to ameliorate MDR, which remains a challenge in cancer treatment.
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Affiliation(s)
- Doris Loh
- Independent Researcher, Marble Falls, TX 78654, USA
- Correspondence: (D.L.); (R.J.R.)
| | - Russel J. Reiter
- Department of Cellular and Structural Biology, UT Health San Antonio, San Antonio, TX 78229, USA
- Correspondence: (D.L.); (R.J.R.)
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Amyloid-beta peptide (25-35) triggers a reorganization of lipid membranes driven by temperature changes. Sci Rep 2021; 11:21990. [PMID: 34754013 PMCID: PMC8578324 DOI: 10.1038/s41598-021-01347-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 10/27/2021] [Indexed: 11/08/2022] Open
Abstract
The amyloid-beta peptide (Aβ) is considered a key factor in Alzheimer's disease (AD) ever since the discovery of the disease. The understanding of its damaging influence has however shifted recently from large fibrils observed in the inter-cellular environment to the small oligomers interacting with a cell membrane. We studied the effect of temperature on the latter interactions by evaluating the structural characteristics of zwitterionic phosphatidylcholine (PC) membranes with incorporated Aβ25–35 peptide. By means of small angle neutron scattering (SANS), we have observed for the first time a spontaneous reformation of extruded unilamellar vesicles (EULVs) to discoidal bicelle-like structures (BLSs) and small unilamellar vesicles (SULVs). These changes in the membrane self-organization happen during the thermodynamic phase transitions of lipids and only in the presence of the peptide. We interpret the dramatic changes in the membrane's overall shape with parallel changes in its thickness as the Aβ25–35 triggered membrane damage and a consequent reorganization of its structure. The suggested process is consistent with an action of separate peptides or small size peptide oligomers rather than the result of large Aβ fibrils.
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Loh D, Reiter RJ. Melatonin: Regulation of Biomolecular Condensates in Neurodegenerative Disorders. Antioxidants (Basel) 2021; 10:1483. [PMID: 34573116 PMCID: PMC8465482 DOI: 10.3390/antiox10091483] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 12/12/2022] Open
Abstract
Biomolecular condensates are membraneless organelles (MLOs) that form dynamic, chemically distinct subcellular compartments organizing macromolecules such as proteins, RNA, and DNA in unicellular prokaryotic bacteria and complex eukaryotic cells. Separated from surrounding environments, MLOs in the nucleoplasm, cytoplasm, and mitochondria assemble by liquid-liquid phase separation (LLPS) into transient, non-static, liquid-like droplets that regulate essential molecular functions. LLPS is primarily controlled by post-translational modifications (PTMs) that fine-tune the balance between attractive and repulsive charge states and/or binding motifs of proteins. Aberrant phase separation due to dysregulated membrane lipid rafts and/or PTMs, as well as the absence of adequate hydrotropic small molecules such as ATP, or the presence of specific RNA proteins can cause pathological protein aggregation in neurodegenerative disorders. Melatonin may exert a dominant influence over phase separation in biomolecular condensates by optimizing membrane and MLO interdependent reactions through stabilizing lipid raft domains, reducing line tension, and maintaining negative membrane curvature and fluidity. As a potent antioxidant, melatonin protects cardiolipin and other membrane lipids from peroxidation cascades, supporting protein trafficking, signaling, ion channel activities, and ATPase functionality during condensate coacervation or dissolution. Melatonin may even control condensate LLPS through PTM and balance mRNA- and RNA-binding protein composition by regulating N6-methyladenosine (m6A) modifications. There is currently a lack of pharmaceuticals targeting neurodegenerative disorders via the regulation of phase separation. The potential of melatonin in the modulation of biomolecular condensate in the attenuation of aberrant condensate aggregation in neurodegenerative disorders is discussed in this review.
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Affiliation(s)
- Doris Loh
- Independent Researcher, Marble Falls, TX 78654, USA
| | - Russel J. Reiter
- Department of Cellular and Structural Biology, UT Health Science Center, San Antonio, TX 78229, USA
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15
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Zambrano P, Suwalsky M, Jemiola-Rzeminska M, Gallardo-Nelson MJ, Strzalka K, Muñoz-Torrero D. Protective Role of a Donepezil-Huprine Hybrid against the β-Amyloid (1-42) Effect on Human Erythrocytes. Int J Mol Sci 2021; 22:ijms22179563. [PMID: 34502472 PMCID: PMC8431064 DOI: 10.3390/ijms22179563] [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: 08/04/2021] [Revised: 08/27/2021] [Accepted: 08/31/2021] [Indexed: 12/17/2022] Open
Abstract
Aβ(1-42) peptide is a neurotoxic agent strongly associated with the etiology of Alzheimer's disease (AD). Current treatments are still of very low effectiveness, and deaths from AD are increasing worldwide. Huprine-derived molecules have a high affinity towards the enzyme acetylcholinesterase (AChE), act as potent Aβ(1-42) peptide aggregation inhibitors, and improve the behavior of experimental animals. AVCRI104P4 is a multitarget donepezil-huprine hybrid that improves short-term memory in a mouse model of AD and exerts protective effects in transgenic Caenorhabditis elegans that express Aβ(1-42) peptide. At present, there is no information about the effects of this compound on human erythrocytes. Thus, we considered it important to study its effects on the cell membrane and erythrocyte models, and to examine its protective effect against the toxic insult induced by Aβ(1-42) peptide in this cell and models. This research was developed using X-ray diffraction and differential scanning calorimetry (DSC) on molecular models of the human erythrocyte membrane constituted by lipid bilayers built of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE). They correspond to phospholipids representative of those present in the external and internal monolayers, respectively, of most plasma and neuronal membranes. The effect of AVCRI104P4 on human erythrocyte morphology was studied by scanning electron microscopy (SEM). The experimental results showed a protective effect of AVCRI104P4 against the toxicity induced by Aβ(1-42) peptide in human erythrocytes and molecular models.
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Affiliation(s)
- Pablo Zambrano
- Facultad de Ciencias Químicas, Universidad de Concepción, Concepción 4030000, Chile
- Correspondence: ; Tel.: +49-89-8578-2374
| | - Mario Suwalsky
- Facultad de Medicina, Universidad Católica de la Santísima Concepción, Concepción 4030000, Chile;
| | - Malgorzata Jemiola-Rzeminska
- Malopolska Centre of Biotechnology, Jagiellonian University, 30-387 Kraków, Poland; (M.J.-R.); (K.S.)
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
| | | | - Kazimierz Strzalka
- Malopolska Centre of Biotechnology, Jagiellonian University, 30-387 Kraków, Poland; (M.J.-R.); (K.S.)
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
| | - Diego Muñoz-Torrero
- Laboratory of Medicinal Chemistry (CSIC Associated Unit), Faculty of Pharmacy and Food, Sciences, University of Barcelona (UB), E-08028 Barcelona, Spain;
- Institute of Biomedicine (IBUB), University of Barcelona (UB), E-08028 Barcelona, Spain
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16
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Khayat E, Lockhart C, Delfing BM, Smith AK, Klimov DK. Met35 Oxidation Hinders Aβ25-35 Peptide Aggregation within the Dimyristoylphosphatidylcholine Bilayer. ACS Chem Neurosci 2021; 12:3225-3236. [PMID: 34383481 DOI: 10.1021/acschemneuro.1c00407] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Using all-atom explicit solvent replica exchange molecular dynamics simulations, we studied the aggregation of oxidized (ox) Aβ25-35 peptides into dimers mediated by the zwitterionic dimyristoylphosphatidylcholine (DMPC) lipid bilayer. By comparing oxAβ25-35 aggregation with that observed for reduced and phosphorylated Aβ25-35 peptides, we elucidated plausible impact of post-translational modifications on cytotoxicity of Aβ peptides involved in Alzheimer's disease. We found that Met35 oxidation reduces helical propensity in oxAβ25-35 peptides bound to the lipid bilayer and enhances backbone fluctuations. These factors destabilize the wild-type head-to-tail dimer interface and lower the aggregation propensity. Met35 oxidation diversifies aggregation pathways by adding monomeric species to the bound conformational ensemble. The oxAβ25-35 dimer becomes partially expelled from the DMPC bilayer and as a result inflicts limited disruption to the bilayer structure compared to wild-type Aβ25-35. Interestingly, the effect of Ser26 phosphorylation is largely opposite, as it preserves the wild-type head-to-tail aggregation interface and strengthens, not weakens, aggregation propensity. The differing effects can be attributed to the sequence locations of these post-translational modifications, since in contrast to Ser26 phosphorylation, Met35 oxidation directly affects the wild-type C-terminal aggregation interface. A comparison with experimental data is provided.
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Affiliation(s)
- Elias Khayat
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Christopher Lockhart
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Bryan M. Delfing
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Amy K. Smith
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Dmitri K. Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
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17
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Reflectometry and molecular dynamics study of the impact of cholesterol and melatonin on model lipid membranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2021; 50:1025-1035. [PMID: 34357445 DOI: 10.1007/s00249-021-01564-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 03/12/2021] [Accepted: 07/30/2021] [Indexed: 10/20/2022]
Abstract
The effect of melatonin and/or cholesterol on the structural properties of a model lipid bilayer prepared from 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) has been investigated both experimentally and via molecular dynamics (MD) simulations. Neutron reflectometry experiments performed with single supported membranes revealed changes in lipid bilayer thickness upon the introduction of additional components. While the presence of cholesterol led to an increase in membrane thickness, the opposite effect was observed in the case of melatonin. The results obtained are in a good agreement with MD simulations which provided further information on the organization of components within the systems examined, indicating a mechanism underlying the membranes' thickness changes due to cholesterol and melatonin that had been observed experimentally. Cholesterol and melatonin preferentially accumulate in different membrane regions, presumably affecting the conformation of lipid hydrophobic moieties differently, and in turn having distinct impacts on the structure of the entire membrane. Our findings may be relevant for understanding the effects of age-related changes in cholesterol and melatonin concentrations, including those in the brains of individuals with Alzheimer's disease.
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18
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Zou X, Himbert S, Dujardin A, Juhasz J, Ros S, Stöver HDH, Rheinstädter MC. Curcumin and Homotaurine Suppress Amyloid-β 25-35 Aggregation in Synthetic Brain Membranes. ACS Chem Neurosci 2021; 12:1395-1405. [PMID: 33826295 DOI: 10.1021/acschemneuro.1c00057] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Amyloid-β (Aβ) peptides spontaneously aggregate into β- and cross-β-sheets in model brain membranes. These nanometer sized can fuse into larger micrometer sized clusters and become extracellular and serve as nuclei for further plaque and fibril growth. Curcumin and homotaurine represent two different types of Aβ aggregation inhibitors. While homotaurine is a peptic antiaggregant that binds to amyloid peptides, curcumin is a nonpeptic molecule that can inhibit aggregation by changing membrane properties. By using optical and fluorescent microscopy, X-ray diffraction, and UV-vis spectroscopy, we study the effect of curcumin and homotaurine on Aβ25-35 aggregates in synthetic brain membranes. Both molecules partition spontaneously and uniformly in membranes and do not lead to observable membrane defects or disruption in our experiments. Both curcumin and homotaurine were found to significantly reduce the number of small, nanoscopic Aβ aggregates and the corresponding β- and cross-β-sheet signals. While a number of research projects focus on potential drug candidates that target Aβ peptides directly, membrane-lipid therapy explores membrane-mediated pathways to suppress peptide aggregation. Based on the results obtained, we conclude that membrane active drugs can be as efficient as peptide targeting drugs in inhibiting amyloid aggregation in vitro.
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Affiliation(s)
- Xingyuan Zou
- Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada
- Origins Institute, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Sebastian Himbert
- Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada
- Origins Institute, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Alix Dujardin
- Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada
- Origins Institute, McMaster University, Hamilton, ON L8S 4L8, Canada
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Janos Juhasz
- Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada
- Department of Medical Physics, Juravinski Cancer Centre, Hamilton, ON L8V 5C2, Canada
| | - Samantha Ros
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Harald D. H. Stöver
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Maikel C. Rheinstädter
- Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada
- Origins Institute, McMaster University, Hamilton, ON L8S 4L8, Canada
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19
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Martí J, Lu H. Microscopic Interactions of Melatonin, Serotonin and Tryptophan with Zwitterionic Phospholipid Membranes. Int J Mol Sci 2021; 22:2842. [PMID: 33799606 PMCID: PMC8001758 DOI: 10.3390/ijms22062842] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/05/2021] [Accepted: 03/08/2021] [Indexed: 12/15/2022] Open
Abstract
The interactions at the atomic level between small molecules and the main components of cellular plasma membranes are crucial for elucidating the mechanisms allowing for the entrance of such small species inside the cell. We have performed molecular dynamics and metadynamics simulations of tryptophan, serotonin, and melatonin at the interface of zwitterionic phospholipid bilayers. In this work, we will review recent computer simulation developments and report microscopic properties, such as the area per lipid and thickness of the membranes, atomic radial distribution functions, angular orientations, and free energy landscapes of small molecule binding to the membrane. Cholesterol affects the behaviour of the small molecules, which are mainly buried in the interfacial regions. We have observed a competition between the binding of small molecules to phospholipids and cholesterol through lipidic hydrogen-bonds. Free energy barriers that are associated to translational and orientational changes of melatonin have been found to be between 10-20 kJ/mol for distances of 1 nm between melatonin and the center of the membrane. Corresponding barriers for tryptophan and serotonin that are obtained from reversible work methods are of the order of 10 kJ/mol and reveal strong hydrogen bonding between such species and specific phospholipid sites. The diffusion of tryptophan and melatonin is of the order of 10-7 cm2/s for the cholesterol-free and cholesterol-rich setups.
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Affiliation(s)
- Jordi Martí
- Department of Physics, Technical University of Catalonia-Barcelona Tech, 08034 Barcelona, Spain
| | - Huixia Lu
- School of Pharmacy, Shanghai Jiaotong University, Shanghai 200240, China;
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20
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Li Y, Tang H, Andrikopoulos N, Javed I, Cecchetto L, Nandakumar A, Kakinen A, Davis TP, Ding F, Ke PC. The membrane axis of Alzheimer's nanomedicine. ADVANCED NANOBIOMED RESEARCH 2021; 1:2000040. [PMID: 33748816 PMCID: PMC7971452 DOI: 10.1002/anbr.202000040] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Alzheimer's disease (AD) is a major neurological disorder impairing its carrier's cognitive function, memory and lifespan. While the development of AD nanomedicine is still nascent, the field is evolving into a new scientific frontier driven by the diverse physicochemical properties and theranostic potential of nanomaterials and nanocomposites. Characteristic to the AD pathology is the deposition of amyloid plaques and tangles of amyloid beta (Aβ) and tau, whose aggregation kinetics may be curbed by nanoparticle inhibitors via sequence-specific targeting or nonspecific interactions with the amyloidogenic proteins. As literature implicates cell membrane as a culprit in AD pathogenesis, here we summarize the membrane axis of AD nanomedicine and present a new rationale that the field development may greatly benefit from harnessing our existing knowledge of Aβ-membrane interaction, nanoparticle-membrane interaction and Aβ-nanoparticle interaction.
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Affiliation(s)
- Yuhuan Li
- Zhongshan Hospital, Fudan University, 111 Yixueyuan Rd, Xuhui District, Shanghai, 200032, China
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Huayuan Tang
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States
| | - Nicholas Andrikopoulos
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Ibrahim Javed
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Qld 4072, Australia
| | - Luca Cecchetto
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- Department of Chemical and Pharmaceutical Science, University of Trieste, Via Licio Giorgieri 1, 34127 Trieste, Italy
| | - Aparna Nandakumar
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Aleksandr Kakinen
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Qld 4072, Australia
| | - Thomas P. Davis
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Qld 4072, Australia
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States
| | - Pu Chun Ke
- Zhongshan Hospital, Fudan University, 111 Yixueyuan Rd, Xuhui District, Shanghai, 200032, China
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
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21
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Luchini A, Vitiello G. Mimicking the Mammalian Plasma Membrane: An Overview of Lipid Membrane Models for Biophysical Studies. Biomimetics (Basel) 2020; 6:biomimetics6010003. [PMID: 33396534 PMCID: PMC7838988 DOI: 10.3390/biomimetics6010003] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 12/23/2020] [Accepted: 12/28/2020] [Indexed: 02/07/2023] Open
Abstract
Cell membranes are very complex biological systems including a large variety of lipids and proteins. Therefore, they are difficult to extract and directly investigate with biophysical methods. For many decades, the characterization of simpler biomimetic lipid membranes, which contain only a few lipid species, provided important physico-chemical information on the most abundant lipid species in cell membranes. These studies described physical and chemical properties that are most likely similar to those of real cell membranes. Indeed, biomimetic lipid membranes can be easily prepared in the lab and are compatible with multiple biophysical techniques. Lipid phase transitions, the bilayer structure, the impact of cholesterol on the structure and dynamics of lipid bilayers, and the selective recognition of target lipids by proteins, peptides, and drugs are all examples of the detailed information about cell membranes obtained by the investigation of biomimetic lipid membranes. This review focuses specifically on the advances that were achieved during the last decade in the field of biomimetic lipid membranes mimicking the mammalian plasma membrane. In particular, we provide a description of the most common types of lipid membrane models used for biophysical characterization, i.e., lipid membranes in solution and on surfaces, as well as recent examples of their applications for the investigation of protein-lipid and drug-lipid interactions. Altogether, promising directions for future developments of biomimetic lipid membranes are the further implementation of natural lipid mixtures for the development of more biologically relevant lipid membranes, as well as the development of sample preparation protocols that enable the incorporation of membrane proteins in the biomimetic lipid membranes.
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Affiliation(s)
- Alessandra Luchini
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark;
| | - Giuseppe Vitiello
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Piazzale Tecchio 80, 80125 Naples, Italy
- CSGI-Center for Colloid and Surface Science, via della Lastruccia 3, 50019 Sesto Fiorentino (Florence), Italy
- Correspondence:
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Khayat E, Klimov DK, Smith AK. Phosphorylation Promotes Aβ25-35 Peptide Aggregation within the DMPC Bilayer. ACS Chem Neurosci 2020; 11:3430-3441. [PMID: 33006281 DOI: 10.1021/acschemneuro.0c00541] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The consequences of phosphorylation of the Aβ25-35 peptide at the position Ser26 on its aggregation have not been examined. To investigate them, we performed all-atom replica exchange simulations probing the binding of phosphorylated Aβ25-35 (pAβ25-35) peptides to the dimyristoyl phosphatidylcholine (DMPC) bilayer and their subsequent aggregation. As a control, we used our previous study of unmodified peptides. We found that phosphorylation moderately reduces the helical propensity in pAβ25-35 and its binding affinity to the DMPC bilayer. Phosphorylation preserves the bimodal binding observed for unmodified Aβ25-35, which features a preferred inserted state and a less probable surface bound state. Phosphorylation also retains the inserted dimer with a head-to-tail helical aggregation interface as the most thermodynamically stable state. Importantly, this post-translation modification strengthens interpeptide interactions by adding a new aggregation "hot spot" created by cross-bridging phosphorylated Ser26 with water, cationic ions, or Lys28. The cross-bridging constitutes the molecular mechanism behind most structural phosphorylation effects. In addition, phosphorylation eliminates pAβ25-35 monomers and diversifies the pool of aggregated species. As a result, it changes the binding and aggregation mechanism by multiplying pathways leading to stable inserted dimers. These findings offer a plausible molecular rationale for experimental observations, including enhanced production of low molecular weight oligomers and cytotoxicity of phosphorylated Aβ peptides.
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Affiliation(s)
- Elias Khayat
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Dmitri K. Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Amy K. Smith
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
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23
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Gastaldo IP, Himbert S, Ram U, Rheinstädter MC. The Effects of Resveratrol, Caffeine, β-Carotene, and Epigallocatechin Gallate (EGCG) on Amyloid- β 25 -- 35 Aggregation in Synthetic Brain Membranes. Mol Nutr Food Res 2020; 64:e2000632. [PMID: 32981185 DOI: 10.1002/mnfr.202000632] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Indexed: 01/08/2023]
Abstract
SCOPE Alzheimer's disease is a neurodegenerative condition marked by the formation and aggregation of amyloid-β (Aβ) peptides. There exists, to this day, no cure or effective prevention for the disease; however, there is evidence that a healthy diet and certain food products can slow down first occurrence and progression. To investigate if food ingredients can interact with peptide aggregates, synthetic membranes that contained aggregates consisting of cross-β sheets of the membrane active fragment A β 25 -- 35 are prepared. METHODS AND RESULTS The impact of resveratrol, found in grapes, caffeine, the main active ingredient in coffee, β-carotene, found in orange fruits and vegetables, and epigallocatechin gallate (EGCG), a component of green tea, on the size and volume fraction of Aβ aggregates is studied using optical and fluorescence microscopy, X-ray diffraction, UV-vis spectroscopy, and molecular dynamics simulations. All compounds are membrane active and spontaneously partitioned in the synthetic brain membranes. While resveratrol and caffeine lead to membrane thickening and reduced membrane fluidity, β-carotene and EGCG preserve or increase fluidity. CONCLUSION Resveratrol and caffeine do not reduce the volume fraction of peptide aggregates while β-carotene significantly reduces plaque size. Interestingly, EGCG dissolves peptide aggregates and significantly decreases the corresponding cross-β and β-sheet signals.
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Affiliation(s)
- Isabella P Gastaldo
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1, Canada.,Origins Institute, McMaster University, Hamilton, Ontario, L8S 4M1, Canada.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, L8S 4M1, Canada
| | - Sebastian Himbert
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1, Canada.,Origins Institute, McMaster University, Hamilton, Ontario, L8S 4M1, Canada
| | - Udbhav Ram
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1, Canada.,Origins Institute, McMaster University, Hamilton, Ontario, L8S 4M1, Canada
| | - Maikel C Rheinstädter
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1, Canada.,Origins Institute, McMaster University, Hamilton, Ontario, L8S 4M1, Canada
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Cellular absorption of small molecules: free energy landscapes of melatonin binding at phospholipid membranes. Sci Rep 2020; 10:9235. [PMID: 32513935 PMCID: PMC7280225 DOI: 10.1038/s41598-020-65753-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Accepted: 05/05/2020] [Indexed: 12/28/2022] Open
Abstract
Free energy calculations are essential to unveil mechanisms at the atomic scale such as binding of small solutes and their translocation across cell membranes, eventually producing cellular absorption. Melatonin regulates biological rhythms and is directly related to carcinogenesis and neurodegenerative disorders. Free energy landscapes obtained from well-tempered metadynamics simulations precisely describe the characteristics of melatonin binding to specific sites in the membrane and reveal the role of cholesterol in free energy barrier crossing. A specific molecular torsional angle and the distance between melatonin and the center of the membrane along the normal to the membrane Z-axis have been considered as suitable reaction coordinates. Free energy barriers between two particular orientations of the molecular structure (folded and extended) have been found to be of about 18 kJ/mol for z-distances of about 1–2 nm. The ability of cholesterol to expel melatonin out of the internal regions of the membrane towards the interface and the external solvent is explained from a free energy perspective. The calculations reported here offer detailed free energy landscapes of melatonin embedded in model cell membranes and reveal microscopic information on its transition between free energy minima, including the location of relevant transition states, and provide clues on the role of cholesterol in the cellular absorption of small molecules.
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25
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Lockhart C, Smith AK, Klimov DK. Three Popular Force Fields Predict Consensus Mechanism of Amyloid β Peptide Binding to the Dimyristoylgylcerophosphocholine Bilayer. J Chem Inf Model 2020; 60:2282-2293. [DOI: 10.1021/acs.jcim.0c00096] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Christopher Lockhart
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Amy K. Smith
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Dmitri K. Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
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26
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Sanderson JM. Far from Inert: Membrane Lipids Possess Intrinsic Reactivity That Has Consequences for Cell Biology. Bioessays 2020; 42:e1900147. [PMID: 31995246 DOI: 10.1002/bies.201900147] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 12/06/2019] [Indexed: 12/19/2022]
Abstract
In this article, it is hypothesized that a fundamental chemical reactivity exists between some non-lipid constituents of cellular membranes and ester-based lipids, the significance of which is not generally recognized. Many peptides and smaller organic molecules have now been shown to undergo lipidation reactions in model membranes in circumstances where direct reaction with the lipid is the only viable route for acyl transfer. Crucially, drugs like propranolol are lipidated in vivo with product profiles that are comparable to those produced in vitro. Some compounds have also been found to promote lipid hydrolysis. Drugs with high lytic activity in vivo tend to have higher toxicity in vitro. Deacylases and lipases are proposed as key enzymes that protect cells against the effects of intrinsic lipidation. The toxic effects of intrinsic lipidation are hypothesized to include a route by which nucleation can occur during the formation of amyloid fibrils.
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27
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Ermilova I, Lyubartsev AP. Modelling of interactions between Aβ(25-35) peptide and phospholipid bilayers: effects of cholesterol and lipid saturation. RSC Adv 2020; 10:3902-3915. [PMID: 35492630 PMCID: PMC9048594 DOI: 10.1039/c9ra06424a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 12/14/2019] [Indexed: 11/25/2022] Open
Abstract
Aggregation of amyloid beta (Aβ) peptides in neuronal membranes is a known promoter of Alzheimer’s disease. To gain insight into the molecular details of Aβ peptide aggregation and its effect on model neuronal membranes, we carried out molecular dynamics simulations of the Aβ(25–35) fragment of the amyloid precursor protein in phospholipid bilayers composed of either fully saturated or highly unsaturated lipids, in the presence or absence of cholesterol. It was found that the peptide does not penetrate through any of the considered membranes, but can reside in the headgroup region and upper part of the lipid tails showing a clear preference to a polyunsaturated cholesterol-free membrane. Due to the ordering and condensing effect upon addition of cholesterol, membranes become more rigid facilitating peptide aggregation on the surface. Except for the case of the cholesterol-free saturated lipid bilayer, the peptides have a small effect on the membrane structure and ordering. It was also found that the most “active” amino-acid for peptide–lipid and peptide–cholesterol interaction is methionine-35, followed by asparagine-27 and serine-26, which form hydrogen bonds between peptides and polar atoms of lipid headgroups. These amino acids are also primarily responsible for peptide aggregation. This work will be relevant for designing strategies to develop drugs to combat Alzheimer’s disease. Molecular dynamics simulations of Aβ(25–35) peptides in phospholipid bilayers are carried out to investigate the effect of polyunsaturated lipids and cholesterol on aggregation of the peptides. ![]()
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Affiliation(s)
- Inna Ermilova
- Department of Materials and Environmental Chemistry, Stockholm University Stockholm Sweden +46 8161193
| | - Alexander P Lyubartsev
- Department of Materials and Environmental Chemistry, Stockholm University Stockholm Sweden +46 8161193
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Hawk LML, Pittman JM, Moore PC, Srivastava AK, Zerweck J, Williams JTB, Hawk AJ, Sachleben JR, Meredith SC. β-amyloid model core peptides: Effects of hydrophobes and disulfides. Protein Sci 2019; 29:527-541. [PMID: 31710741 DOI: 10.1002/pro.3778] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/30/2019] [Accepted: 10/31/2019] [Indexed: 12/22/2022]
Abstract
The mechanism by which a disordered peptide nucleates and forms amyloid is incompletely understood. A central domain of β-amyloid (Aβ21-30) has been proposed to have intrinsic structural propensities that guide the limited formation of structure in the process of fibrillization. In order to test this hypothesis, we examine several internal fragments of Aβ, and variants of these either cyclized or with an N-terminal Cys. While Aβ21-30 and variants were always monomeric and unstructured (circular dichroism (CD) and nuclear magnetic resonance spectroscopy (NMRS)), we found that the addition of flanking hydrophobic residues in Aβ16-34 led to formation of typical amyloid fibrils. NMR showed no long-range nuclear overhauser effect (nOes) in Aβ21-30, Aβ16-34, or their variants, however. Serial 1 H-15 N-heteronuclear single quantum coherence spectroscopy, 1 H-1 H nuclear overhauser effect spectroscopy, and 1 H-1 H total correlational spectroscopy spectra were used to follow aggregation of Aβ16-34 and Cys-Aβ16-34 at a site-specific level. The addition of an N-terminal Cys residue (in Cys-Aβ16-34) increased the rate of fibrillization which was attributable to disulfide bond formation. We propose a scheme comparing the aggregation pathways for Aβ16-34 and Cys-Aβ16-34, according to which Cys-Aβ16-34 dimerizes, which accelerates fibril formation. In this context, cysteine residues form a focal point that guides fibrillization, a role which, in native peptides, can be assumed by heterogeneous nucleators of aggregation.
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Affiliation(s)
- Laura M L Hawk
- Department of Chemistry, The University of Chicago, Chicago, Illinois
| | - Jay M Pittman
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois
| | - Patrick C Moore
- Department of Pathology, The University of Chicago, Chicago, Illinois
| | - Atul K Srivastava
- Department of Pathology, The University of Chicago, Chicago, Illinois
| | - Jonathan Zerweck
- Department of Pathology, The University of Chicago, Chicago, Illinois
| | | | - Andrew J Hawk
- Department of Pathology, The University of Chicago, Chicago, Illinois
| | - Joseph R Sachleben
- Biomolecular NMR Core Facility, The University of Chicago, Chicago, Illinois
| | - Stephen C Meredith
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois.,Department of Pathology, The University of Chicago, Chicago, Illinois
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29
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Al-Akayleh F, Mohammed Ali HH, Ghareeb MM, Al-Remawi M. Therapeutic deep eutectic system of capric acid and menthol: Characterization and pharmaceutical application. J Drug Deliv Sci Technol 2019. [DOI: 10.1016/j.jddst.2019.101159] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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30
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Fabiani C, Antollini SS. Alzheimer's Disease as a Membrane Disorder: Spatial Cross-Talk Among Beta-Amyloid Peptides, Nicotinic Acetylcholine Receptors and Lipid Rafts. Front Cell Neurosci 2019; 13:309. [PMID: 31379503 PMCID: PMC6657435 DOI: 10.3389/fncel.2019.00309] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 06/25/2019] [Indexed: 12/17/2022] Open
Abstract
Biological membranes show lateral and transverse asymmetric lipid distribution. Cholesterol (Chol) localizes in both hemilayers, but in the external one it is mostly condensed in lipid-ordered microdomains (raft domains), together with saturated phosphatidyl lipids and sphingolipids (including sphingomyelin and glycosphingolipids). Membrane asymmetries induce special membrane biophysical properties and behave as signals for several physiological and/or pathological processes. Alzheimer’s disease (AD) is associated with a perturbation in different membrane properties. Amyloid-β (Aβ) plaques and neurofibrillary tangles of tau protein together with neuroinflammation and neurodegeneration are the most characteristic cellular changes observed in this disease. The extracellular presence of Aβ peptides forming senile plaques, together with soluble oligomeric species of Aβ, are considered the major cause of the synaptic dysfunction of AD. The association between Aβ peptide and membrane lipids has been extensively studied. It has been postulated that Chol content and Chol distribution condition Aβ production and posterior accumulation in membranes and, hence, cell dysfunction. Several lines of evidence suggest that Aβ partitions in the cell membrane accumulate mostly in raft domains, the site where the cleavage of the precursor AβPP by β- and γ- secretase is also thought to occur. The main consequence of the pathogenesis of AD is the disruption of the cholinergic pathways in the cerebral cortex and in the basal forebrain. In parallel, the nicotinic acetylcholine receptor has been extensively linked to membrane properties. Since its transmembrane domain exhibits extensive contacts with the surrounding lipids, the acetylcholine receptor function is conditioned by its lipid microenvironment. The nicotinic acetylcholine receptor is present in high-density clusters in the cell membrane where it localizes mainly in lipid-ordered domains. Perturbations of sphingomyelin or cholesterol composition alter acetylcholine receptor location. Therefore, Aβ processing, Aβ partitioning, and acetylcholine receptor location and function can be manipulated by changes in membrane lipid biophysics. Understanding these mechanisms should provide insights into new therapeutic strategies for prevention and/or treatment of AD. Here, we discuss the implications of lipid-protein interactions at the cell membrane level in AD.
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Affiliation(s)
- Camila Fabiani
- Instituto de Investigaciones Bioquímicas de Bahía Blanca CONICET-UNS, Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Silvia S Antollini
- Instituto de Investigaciones Bioquímicas de Bahía Blanca CONICET-UNS, Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina
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31
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Karimi H, Heydari Dokoohaki M, Zolghadr AR, Ghatee MH. The interactions of an Aβ protofibril with a cholesterol-enriched membrane and involvement of neuroprotective carbazolium-based substances. Phys Chem Chem Phys 2019; 21:11066-11078. [PMID: 31090756 DOI: 10.1039/c9cp00859d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Recent studies have shown that the aggregation of the amyloid-beta peptide (Aβ) in the brain cell membrane is responsible for the emergence of Alzheimer's disease (AD); the exploration of effective factors involved in the extension of the aggregation process and alternatively the examination of an effective inhibitor via theoretical and experimental tools are among the main research topics in the field of AD treatment. Therefore, in this study, we used all-atom molecular dynamics (MD) simulations to clarify the impact of cell membrane cholesterol on the interaction of Aβ with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) as a membrane model. Moreover, the effect of the P7C3-S243 molecule on the abovementioned process was investigated. The simulation results disclosed the neuroprotective property of the P7C3-S243 molecule. The MD simulation results indicate that the interaction of cholesterol molecules with the Aβ oligomer is negligible and cannot enhance membrane rupture. However, strong hydrogen bonding between the POPC molecules and the oligomers led to membrane perturbation. According to our modellings, the P7C3-S243 molecular layer can protect the cell membrane by inhibiting the direct interaction between the bilayer and Aβ. In addition, free-energy calculations were conducted to determine the possible penetration of Aβ fibrils into the cholesterol-enriched membrane.
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Affiliation(s)
- Hedayat Karimi
- Department of Chemistry, Shiraz University, Shiraz, 71946-84795, Iran.
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32
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De novo aggregation of Alzheimer's Aβ25-35 peptides in a lipid bilayer. Sci Rep 2019; 9:7161. [PMID: 31073226 PMCID: PMC6509337 DOI: 10.1038/s41598-019-43685-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 04/27/2019] [Indexed: 11/28/2022] Open
Abstract
A potential mechanism of cytotoxicity attributed to Alzheimer’s Aβ peptides postulates that their aggregation disrupts membrane structure causing uncontrollable permeation of Ca2+ ions. To gain molecular insights into these processes, we have performed all-atom explicit solvent replica exchange with solute tempering molecular dynamics simulations probing aggregation of the naturally occurring Aβ fragment Aβ25-35 within the DMPC lipid bilayer. To compare the impact produced on the bilayer by Aβ25-35 oligomers and monomers, we used as a control our previous simulations, which explored binding of Aβ25-35 monomers to the same bilayer. We found that compared to monomeric species aggregation results in much deeper insertion of Aβ25-35 peptides into the bilayer hydrophobic core causing more pronounced disruption in its structure. Aβ25-35 peptides aggregate by incorporating monomer-like structures with stable C-terminal helix. As a result the Aβ25-35 dimer features unusual helix head-to-tail topology supported by a parallel off-registry interface. Such topology affords further growth of an aggregate by recruiting additional peptides. Free energy landscape reveals that inserted dimers represent the dominant equilibrium state augmented by two metastable states associated with surface bound dimers and inserted monomers. Using the free energy landscape we propose the pathway of Aβ25-35 binding, aggregation, and insertion into the lipid bilayer.
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33
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Schmidt A, Alsop RJ, Rimal R, Lenzig P, Joussen S, Gervasi NN, Khondker A, Gründer S, Rheinstädter MC, Wiemuth D. Modulation of DEG/ENaCs by Amphiphiles Suggests Sensitivity to Membrane Alterations. Biophys J 2019; 114:1321-1335. [PMID: 29590590 DOI: 10.1016/j.bpj.2018.01.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 01/22/2018] [Accepted: 01/26/2018] [Indexed: 12/25/2022] Open
Abstract
The bile acid-sensitive ion channel is activated by amphiphilic substances such as bile acids or artificial detergents via membrane alterations; however, the mechanism of membrane sensitivity of the bile acid-sensitive ion channel is not known. It has also not been systematically investigated whether other members of the degenerin/epithelial Na+ channel (DEG/ENaC) gene family are affected by amphiphilic compounds. Here, we show that DEG/ENaCs ASIC1a, ASIC3, ENaC, and the purinergic receptor P2X2 are modulated by a large number of different, structurally unrelated amphiphilic substances, namely the detergents N-lauroylsarcosine, Triton X-100, and β-octylglucoside; the fenamate flufenamic acid; the antipsychotic drug chlorpromazine; the natural phenol resveratrol; the chili pepper compound capsaicin; the loop diuretic furosemide; and the antiarrythmic agent verapamil. We determined the modification of membrane properties using large-angle x-ray diffraction experiments on model lipid bilayers, revealing that the amphiphilic compounds are positioned in a characteristic fashion either in the lipid tail group region or in the lipid head group region, demonstrating that they perturbed the membrane structure. Collectively, our results show that DEG/ENaCs and structurally related P2X receptors are modulated by diverse amphiphilic molecules. Furthermore, they suggest alterations of membrane properties by amphiphilic compounds as a mechanism contributing to modulation.
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Affiliation(s)
- Axel Schmidt
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Rick J Alsop
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Rahul Rimal
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Pia Lenzig
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Sylvia Joussen
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Natalie N Gervasi
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Adree Khondker
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Stefan Gründer
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | | | - Dominik Wiemuth
- Institute of Physiology, RWTH Aachen University, Aachen, Germany.
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34
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Structure of amyloid β 25-35 in lipid environment and cholesterol-dependent membrane pore formation. Sci Rep 2019; 9:2689. [PMID: 30804528 PMCID: PMC6389947 DOI: 10.1038/s41598-019-38749-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 01/08/2019] [Indexed: 01/14/2023] Open
Abstract
The amyloid β (Aβ) peptide and its shorter variants, including a highly cytotoxic Aβ25–35 peptide, exert their neurotoxic effect during Alzheimer’s disease by various mechanisms, including cellular membrane permeabilization. The intrinsic polymorphism of Aβ has prevented the identification of the molecular basis of Aβ pore formation by direct structural methods, and computational studies have led to highly divergent pore models. Here, we have employed a set of biophysical techniques to directly monitor Ca2+-transporting Aβ25–35 pores in lipid membranes, to quantitatively characterize pore formation, and to identify the key structural features of the pore. Moreover, the effect of membrane cholesterol on pore formation and the structure of Aβ25–35 has been elucidated. The data suggest that the membrane-embedded peptide forms 6- or 8-stranded β-barrel like structures. The 8-stranded barrels may conduct Ca2+ ions through an inner cavity, whereas the tightly packed 6-stranded barrels need to assemble into supramolecular structures to form a central pore. Cholesterol affects Aβ25–35 pore formation by a dual mechanism, i.e., by direct interaction with the peptide and by affecting membrane structure. Collectively, our data illuminate the molecular basis of Aβ membrane pore formation, which should advance both basic and clinical research on Alzheimer’s disease and membrane-associated pathologies in general.
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35
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Singh J, Peric M. Interaction of the β amyloid - Aβ(25-35) - peptide with zwitterionic and negatively charged vesicles with and without cholesterol. Chem Phys Lipids 2018; 216:39-47. [PMID: 30222975 DOI: 10.1016/j.chemphyslip.2018.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 09/07/2018] [Accepted: 09/11/2018] [Indexed: 12/11/2022]
Abstract
The interactions of the Alzheimer's β-amyloid peptide, Aβ(25-35), with 18:1 (Δ9-Cis) PC 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), L-α-phosphatidylcholine (EPC), 1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (sodium salt) (DOPG), and L-α-phosphatidylglycerol (EPG) phospholipid vesicles with and without cholesterol (Ch) are studied by the nitroxide spin probe electron paramagnetic resonance (EPR) method. Two nitroxide spin probes, 2,2,6,6-tetramethyl-piperidin-1-oxyl-4-yl hexadecanoate (TP, TEMPO-Palmitate) and 2-Ethyl-2-(15-methoxy-15-oxopentadecyl)-4,4-dimethyl-3-oxazolidinyloxy (16-DSE), are utilized in the study. TEMPO-Palmitate has the reporting EPR moiety located at the top of this spin probe, while 16-DSE has the reporting EPR moiety located at the tail of the spin probe. These two probes enable us to sample the surface and the middle of the phospholipid bilayer, respectively. All EPR measurements are done above the melting points of all four phospholipids when the bilayer is in the liquid crystal phase, the physiologically relevant phase. Due to non-linear spectral line fitting, the EPR spectral parameters are extracted with high precision. The results show that there are two populations of Aβ(25-35) and that one of them is located in the hydrophobic phospholipid layer below the hydrophilic headgroup region. The second population appears to be weakly coupled to the surface of the bilayer. Both hydrophobic and electrostatic interactions affect the insertion of Aβ(25-35) in the bilayer. Also, there is strong evidence for an interaction between cholesterol and Aβ(25-35), which affects the dielectric and dynamic properties of the bilayer.
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Affiliation(s)
- Jasmeet Singh
- Department of Physics and Astronomy and The Center for Supramolecular Studies, California State University at Northridge, Northridge, California 91330, United States
| | - Miroslav Peric
- Department of Physics and Astronomy and The Center for Supramolecular Studies, California State University at Northridge, Northridge, California 91330, United States.
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36
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Khondker A, Alsop RJ, Himbert S, Tang J, Shi AC, Hitchcock AP, Rheinstädter MC. Membrane-Modulating Drugs can Affect the Size of Amyloid-β 25-35 Aggregates in Anionic Membranes. Sci Rep 2018; 8:12367. [PMID: 30120270 PMCID: PMC6098001 DOI: 10.1038/s41598-018-30431-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 07/30/2018] [Indexed: 01/08/2023] Open
Abstract
The formation of amyloid-β plaques is one of the hallmarks of Alzheimer's disease. The presence of an amphiphatic cell membrane can accelerate the formation of amyloid-β aggregates, making it a potential druggable target to delay the progression of Alzheimer's disease. We have prepared unsaturated anionic membranes made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1,2-dimyristoyl-sn-glycero-3-phospho-L-serine (DMPS) and added the trans-membrane segment Aβ25-35. Peptide plaques spontaneously form in these membranes at high peptide concentrations of 20 mol%, which show the characteristic cross-β motif (concentrations are relative to the number of membrane lipids and indicate the peptide-to-lipid ratio). We used atomic force microscopy, fluorescence microscopy, x-ray microscopy, x-ray diffraction, UV-vis spectroscopy and Molecular Dynamics (MD) simulations to study three membrane-active molecules which have been speculated to have an effect in Alzheimer's disease: melatonin, acetylsalicyclic acid (ASA) and curcumin at concentrations of 5 mol% (drug-to-peptide ratio). Melatonin did not change the structural parameters of the membranes and did not impact the size or extent of peptide clusters. While ASA led to a membrane thickening and stiffening, curcumin made membranes softer and thinner. As a result, ASA was found to lead to the formation of larger peptide aggregates, whereas curcumin reduced the volume fraction of cross-β sheets by ~70%. We speculate that the interface between membrane and peptide cluster becomes less favorable in thick and stiff membranes, which favors the formation of larger aggregates, while the corresponding energy mismatch is reduced in soft and thin membranes. Our results present evidence that cross-β sheets of Aβ25-35 in anionic unsaturated lipid membranes can be re-dissolved by changing membrane properties to reduce domain mismatch.
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Affiliation(s)
- Adree Khondker
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada.,Origins Institute, McMaster University, Hamilton, Ontario, Canada
| | - Richard J Alsop
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada.,Origins Institute, McMaster University, Hamilton, Ontario, Canada
| | - Sebastian Himbert
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada.,Origins Institute, McMaster University, Hamilton, Ontario, Canada
| | - Jennifer Tang
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada.,Origins Institute, McMaster University, Hamilton, Ontario, Canada
| | - An-Chang Shi
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Adam P Hitchcock
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada
| | - Maikel C Rheinstädter
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada. .,Origins Institute, McMaster University, Hamilton, Ontario, Canada.
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37
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Smith AK, Klimov DK. Binding of Cytotoxic Aβ25–35 Peptide to the Dimyristoylphosphatidylcholine Lipid Bilayer. J Chem Inf Model 2018; 58:1053-1065. [DOI: 10.1021/acs.jcim.8b00045] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Amy K. Smith
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Dmitri K. Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
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38
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Zhang X, London E, Raleigh DP. Sterol Structure Strongly Modulates Membrane-Islet Amyloid Polypeptide Interactions. Biochemistry 2018; 57:1868-1879. [PMID: 29373018 DOI: 10.1021/acs.biochem.7b01190] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Amyloid formation has been implicated in a wide range of human diseases, and the interaction of amyloidogenic proteins with membranes are believed to be important for many of them. In type-2 diabetes, human islet amyloid polypeptide (IAPP) forms amyloids, which contribute to β-cell death and dysfunction in the disease. IAPP-membrane interactions are potential mechanisms of cytotoxicity. In vitro studies have shown that cholesterol significantly modulates the ability of model membranes to induce IAPP amyloid formation and IAPP-mediated membrane damage. It is not known if this is due to the general effects of cholesterol on membranes or because of specific sterol-IAPP interactions. The effects of replacing cholesterol with eight other sterols/steroids on IAPP binding to model membranes, membrane disruption, and membrane-mediated amyloid formation were examined. The primary effect of the sterols/steroids on the IAPP-membrane interactions was found to reflect their effect upon membrane order as judged by fluorescence anisotropy measurements. Specific IAPP-sterol/steroid interactions have smaller effects. The fraction of vesicles that bind IAPP was inversely correlated with the sterols/steroids' effect on membrane order, as was the extent of IAPP-induced membrane leakage and the time to form amyloids. The correlation between the fraction of vesicles binding IAPP and membrane leakage was particularly tight, suggesting the restriction of IAPP to a subset of vesicles is responsible for incomplete leakage.
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39
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Liu Y, Ren B, Zhang Y, Sun Y, Chang Y, Liang G, Xu L, Zheng J. Molecular simulation aspects of amyloid peptides at membrane interface. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1906-1916. [PMID: 29421626 DOI: 10.1016/j.bbamem.2018.02.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 12/13/2022]
Abstract
The interactions of amyloid peptides with cell membranes play an important role in maintaining the integrity and functionality of cell membrane. A thorough molecular-level understanding of the structure, dynamics, and interactions between amyloid peptides and cell membranes is critical to amyloid aggregation and toxicity mechanisms for the bench-to-bedside applications. Here we review the most recent computational studies of amyloid peptides at model cell membranes. Different mechanisms of action of amyloid peptides on/in cell membranes, targeted by different computational techniques at different lengthscales and timescales, are rationally discussed. Finally, we have proposed some new insights into the remaining challenges and perspectives for future studies to improve our understanding of the activity of amyloid peptides associated with protein-misfolding diseases. 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)
- Yonglan Liu
- Hunan Key Laboratory of Biomedical Nanomaterials and Devices, College of Life Science and Chemistry, Hunan University of Technology, Zhuzhou 412007, PR China; Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325, United States
| | - Baiping Ren
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325, United States
| | - Yanxian Zhang
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325, United States
| | - 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 300072, China
| | - Yung Chang
- R&D Center for Membrane Technology and Department of Chemical EngineeringChung Yuan Christian University, Chung-Li, Taoyuan 320, Taiwan
| | - Guizhao Liang
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, PR China
| | - Lijian Xu
- Hunan Key Laboratory of Biomedical Nanomaterials and Devices, College of Life Science and Chemistry, Hunan University of Technology, Zhuzhou 412007, PR China; Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325, United States.
| | - Jie Zheng
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325, United States.
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40
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Khondker A, Alsop RJ, Dhaliwal A, Saem S, Moran-Mirabal JM, Rheinstädter MC. Membrane Cholesterol Reduces Polymyxin B Nephrotoxicity in Renal Membrane Analogs. Biophys J 2017; 113:2016-2028. [PMID: 29117525 DOI: 10.1016/j.bpj.2017.09.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 08/17/2017] [Accepted: 09/13/2017] [Indexed: 01/21/2023] Open
Abstract
Polymyxin B (PmB) is a "last-line" antibiotic scarcely used due to its nephrotoxicity. However, the molecular basis for antibiotic nephrotoxicity is not clearly understood. We prepared kidney membrane analogs of detergent-susceptible membranes, depleted of cholesterol, and cholesterol enriched, resistant membranes. In both analogs, PmB led to membrane damage. By combining x-ray diffraction, molecular dynamics simulations, and electrochemistry, we present evidence for two populations of PmB molecules: peptides that lie flat on the membranes, and an inserted state. In cholesterol depleted membranes, PmB forms clusters on the membranes leading to an indentation of the bilayers and increase in water permeation. The inserted peptides formed aggregates in the membrane core leading to further structural instabilities and increased water intake. The presence of cholesterol in the resistant membrane analogs led to a significant decrease in membrane damage. Although cholesterol did not inhibit peptide insertion, it minimized peptide clustering and water intake through stabilization of the bilayer structure and suppression of lipid and peptide mobility.
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Affiliation(s)
- Adree Khondker
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Richard J Alsop
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Alexander Dhaliwal
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Sokunthearath Saem
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada
| | - Jose M Moran-Mirabal
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada
| | - Maikel C Rheinstädter
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada.
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Kandel N, Zheng T, Huo Q, Tatulian SA. Membrane Binding and Pore Formation by a Cytotoxic Fragment of Amyloid β Peptide. J Phys Chem B 2017; 121:10293-10305. [PMID: 29039658 DOI: 10.1021/acs.jpcb.7b07002] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Amyloid β (Aβ) peptide contributes to Alzheimer's disease by a yet unidentified mechanism. In the brain tissue, Aβ occurs in various forms, including an undecapeptide Aβ25-35, which exerts a neurotoxic effect through the mitochondrial dysfunction and/or Ca2+-permeable pore formation in cell membranes. This work was aimed at the biophysical characterization of membrane binding and pore formation by Aβ25-35. Interaction of Aβ25-35 with anionic and zwitterionic membranes was analyzed by microelectrophoresis. In pore formation experiments, Aβ25-35 was incubated in aqueous buffer to form oligomers and added to Quin-2-loaded vesicles. Gradual increase in Quin-2 fluorescence was interpreted in terms of membrane pore formation by the peptide, Ca2+ influx, and binding to intravesicular Quin-2. The kinetics and magnitude of this process were used to evaluate the rate constant of pore formation, peptide-peptide association constants, and the oligomeric state of the pores. Decrease in membrane anionic charge and high ionic strength conditions significantly suppressed membrane binding and pore formation, indicating the importance of electrostatic interactions in these events. Circular dichroism spectroscopy showed that Aβ25-35 forms the most efficient pores in β-sheet conformation. The data are consistent with an oligo-oligomeric pore model composed of up to eight peptide units, each containing 6-8 monomers.
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Affiliation(s)
| | | | | | - Suren A Tatulian
- Department of Physics, University of Central Florida , Physical Sciences Bldg., Room 456, 4111 Libra Drive, Orlando, Florida 32816, United States
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42
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Lockhart C, Klimov DK. Cholesterol Changes the Mechanisms of Aβ Peptide Binding to the DMPC Bilayer. J Chem Inf Model 2017; 57:2554-2565. [PMID: 28910085 DOI: 10.1021/acs.jcim.7b00431] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using isobaric-isothermal all-atom replica-exchange molecular dynamics (REMD) simulations, we investigated the equilibrium binding of Aβ10-40 monomers to the zwitterionic dimyristoylphosphatidylcholine (DMPC) bilayer containing cholesterol. Our previous REMD simulations, which studied binding of the same peptide to the cholesterol-free DMPC bilayer, served as a control, against which we measured the impact of cholesterol. Our findings are as follows. First, addition of cholesterol to the DMPC bilayer partially expels the Aβ peptide from the hydrophobic core and promotes its binding to bilayer polar headgroups. Using thermodynamic and energetics analyses, we argued that Aβ partial expulsion is not related to cholesterol-induced changes in lateral pressure within the bilayer but is caused by binding energetics, which favors Aβ binding to the surface of the densely packed cholesterol-rich bilayer. Second, cholesterol has a protective effect on the DMPC bilayer structure against perturbations caused by Aβ binding. More specifically, cholesterol reduces bilayer thinning and overall depletion of bilayer density beneath the Aβ binding footprint. Third, we found that the Aβ peptide contains a single cholesterol binding site, which involves hydrophobic C-terminal amino acids (Ile31-Val36), Phe19, and Phe20 from the central hydrophobic cluster, and cationic Lys28 from the turn region. This binding site accounts for about 76% of all Aβ-cholesterol interactions. Because cholesterol binding site in the Aβ10-40 peptide does not contain the GXXXG motif featured in cholesterol interactions with the transmembrane domain C99 of the β-amyloid precursor protein, we argued that the binding mechanisms for Aβ and C99 are distinct reflecting their different conformations and positions in the lipid bilayer. Fourth, cholesterol sharply reduces the helical propensity in the bound Aβ peptide. As a result, cholesterol largely eliminates the emergence of helical structure observed upon Aβ transition from a water environment to the cholesterol-free DMPC bilayer. We explain this effect by the formation of hydrogen bonds between cholesterol and the Aβ backbone, which prevent helix formation. Taken together, we expect that our simulations will advance understanding of a molecular-level mechanism behind the role of cholesterol in Alzheimer's disease.
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Affiliation(s)
- Christopher Lockhart
- School of Systems Biology, George Mason University , Manassas, Virginia 20110, United States
| | - Dmitri K Klimov
- School of Systems Biology, George Mason University , Manassas, Virginia 20110, United States
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43
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Membrane-Accelerated Amyloid-β Aggregation and Formation of Cross-β Sheets. MEMBRANES 2017; 7:membranes7030049. [PMID: 28858214 PMCID: PMC5618134 DOI: 10.3390/membranes7030049] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 07/26/2017] [Accepted: 08/23/2017] [Indexed: 11/17/2022]
Abstract
Amyloid- β aggregates play a causative role in Alzheimer's disease. These aggregates are a product of the physical environment provided by the basic neuronal membrane, composed of a lipid bilayer. The intrinsic properties of the lipid bilayer allow amyloid- β peptides to nucleate and form well-ordered cross- β sheets within the membrane. Here, we correlate the aggregation of the hydrophobic fragment of the amyloid- β protein, A β 25 - 35 , with the hydrophobicity, fluidity, and charge density of a lipid bilayer. We summarize recent biophysical studies of model membranes and relate these to the process of aggregation in physiological systems.
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44
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Alsop RJ, Dhaliwal A, Rheinstädter MC. Curcumin Protects Membranes through a Carpet or Insertion Model Depending on Hydration. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:8516-8524. [PMID: 28548854 DOI: 10.1021/acs.langmuir.7b01562] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Curcumin is the main ingredient in turmeric, a common Indian spice. Curcumin shows a broad spectrum of effects, including anti-Alzheimer's and antioxidant properties. An interaction between curcumin and lipid membranes has been speculated as the root cause of this activity, and the molecule is often proposed to protect the bilayer. However, the detailed molecular mechanism of this protection is disputed. There is evidence that curcumin either (a) lies flat on the bilayer and provides a "carpet" for protection by forming a steric barrier, or (b) inserts into the membrane and stiffens tails, thereby protecting against peptide insertion. We studied the interaction between curcumin and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) bilayers at different concentrations using high-resolution X-ray diffraction and molecular dynamics (MD) computer simulations. We observed curcumin molecules forming a carpet in dehydrated bilayers, whereas in hydrated membranes the curcumin molecules were found to insert into the bilayers. From calculations of the potential of mean force (PMF), we find two minima, a metastable state in the headgroup region, at |z| ≈ 22 Å, and a global minimum in the hydrophobic membrane core, at |z| ≈ 9 Å. The population of the two states depends on membrane hydration. Experiments may thus observe curcumin in a carpet or inserted position, depending on the osmotic pressure conditions created, for instance, by salts, buffer solutions, substrates, or macromolecular solutes. In the carpet model, curcumin dehydrates lipid bilayers and decreases fluidity. When inserted, curcumin leads to a further fluidification of the membranes and an increase in tail fluctuations, contrary to cholesterol's condensing effect.
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Affiliation(s)
- Richard J Alsop
- Department of Physics and Astronomy, McMaster University , Hamilton, Ontario L8S 4M1, Canada
| | - Alexander Dhaliwal
- Department of Physics and Astronomy, McMaster University , Hamilton, Ontario L8S 4M1, Canada
| | - Maikel C Rheinstädter
- Department of Physics and Astronomy, McMaster University , Hamilton, Ontario L8S 4M1, Canada
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45
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The Molecular Structure of Human Red Blood Cell Membranes from Highly Oriented, Solid Supported Multi-Lamellar Membranes. Sci Rep 2017; 7:39661. [PMID: 28045119 PMCID: PMC5206716 DOI: 10.1038/srep39661] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 11/24/2016] [Indexed: 12/30/2022] Open
Abstract
We prepared highly oriented, multi-lamellar stacks of human red blood cell (RBC) membranes applied on silicon wafers. RBC ghosts were prepared by hemolysis and applied onto functionalized silicon chips and annealed into multi-lamellar RBC membranes. High resolution X-ray diffraction was used to determine the molecular structure of the stacked membranes. We present direct experimental evidence that these RBC membranes consist of nanometer sized domains of integral coiled-coil peptides, as well as liquid ordered (lo) and liquid disordered (ld) lipids. Lamellar spacings, membrane and hydration water layer thicknesses, areas per lipid tail and domain sizes were determined. The common drug aspirin was added to the RBC membranes and found to interact with RBC membranes and preferably partition in the head group region of the lo domain leading to a fluidification of the membranes, i.e., a thinning of the bilayers and an increase in lipid tail spacing. Our results further support current models of RBC membranes as patchy structures and provide unprecedented structural details of the molecular organization in the different domains.
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46
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Parikh N, Klimov DK. Inclusion of lipopeptides into the DMPC lipid bilayers prevents Aβ peptide insertion. Phys Chem Chem Phys 2017; 19:10087-10098. [DOI: 10.1039/c7cp01003f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lipopeptides prevent penetration of Alzheimer's Aβ peptides into lipid bilayers.
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Affiliation(s)
- Niyati Parikh
- School of Systems Biology
- George Mason University
- Manassas
- USA
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47
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Brown AM, Bevan DR. Influence of sequence and lipid type on membrane perturbation by human and rat amyloid β-peptide (1–42). Arch Biochem Biophys 2017; 614:1-13. [DOI: 10.1016/j.abb.2016.11.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 11/17/2016] [Accepted: 11/20/2016] [Indexed: 12/20/2022]
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48
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Schmidt A, Löhrer D, Alsop RJ, Lenzig P, Oslender-Bujotzek A, Wirtz M, Rheinstädter MC, Gründer S, Wiemuth D. A Cytosolic Amphiphilic α-Helix Controls the Activity of the Bile Acid-sensitive Ion Channel (BASIC). J Biol Chem 2016; 291:24551-24565. [PMID: 27679529 DOI: 10.1074/jbc.m116.756437] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 09/19/2016] [Indexed: 12/22/2022] Open
Abstract
The bile acid-sensitive ion channel (BASIC) is a member of the degenerin/epithelial Na+ channel (Deg/ENaC) family of ion channels. It is mainly found in bile duct epithelial cells, the intestinal tract, and the cerebellum and is activated by alterations of its membrane environment. Bile acids, one class of putative physiological activators, exert their effect by changing membrane properties, leading to an opening of the channel. The physiological function of BASIC, however, is unknown. Deg/ENaC channels are characterized by a trimeric subunit composition. Each subunit is composed of two transmembrane segments, which are linked by a large extracellular domain. The termini of the channels protrude into the cytosol. Many Deg/ENaC channels contain regulatory domains and sequence motifs within their cytosolic domains. In this study, we show that BASIC contains an amphiphilic α-helical structure within its N-terminal domain. This α-helix binds to the cytosolic face of the plasma membrane and stabilizes a closed state. Truncation of this domain renders the channel hyperactive. Collectively, we identify a cytoplasmic domain, unique to BASIC, that controls channel activity via membrane interaction.
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Affiliation(s)
- Axel Schmidt
- From the Institute of Physiology, RWTH Aachen University, D-52074 Aachen, Germany and
| | - Daniel Löhrer
- From the Institute of Physiology, RWTH Aachen University, D-52074 Aachen, Germany and
| | - Richard J Alsop
- the Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Pia Lenzig
- From the Institute of Physiology, RWTH Aachen University, D-52074 Aachen, Germany and
| | | | - Monika Wirtz
- From the Institute of Physiology, RWTH Aachen University, D-52074 Aachen, Germany and
| | - Maikel C Rheinstädter
- the Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Stefan Gründer
- From the Institute of Physiology, RWTH Aachen University, D-52074 Aachen, Germany and
| | - Dominik Wiemuth
- From the Institute of Physiology, RWTH Aachen University, D-52074 Aachen, Germany and.
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49
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Alsop RJ, Maria Schober R, Rheinstädter MC. Swelling of phospholipid membranes by divalent metal ions depends on the location of the ions in the bilayers. SOFT MATTER 2016; 12:6737-6748. [PMID: 27453289 DOI: 10.1039/c6sm00695g] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The Hofmeister series illustrates how salts produce a wide range of effects in biological systems, which are not exclusively explained by ion charge. In lipid membranes, charged ions have been shown to bind to lipids and either hydrate or dehydrate lipid head groups, and also to swell the water layer in multi-lamellar systems. Typically, Hofmeister phenomena are explained by the interaction of the ions with water, as well as with biological interfaces, such as proteins or membranes. We studied the effect of the divalent cations Mg(2+), Ca(2+), Fe(2+), and Zn(2+) on oriented, stacked, phospholipid bilayers made of dimyristoylphosphatidylcholine (DMPC). Using high-resolution X-ray diffraction, we observed that the cations lead to a swelling of the water layer between the bilayers, without causing significant changes to the bilayer structure. The cations swelled the bilayers in different amounts, in the order Fe(2+) > Mg(2+) > Ca(2+) > Zn(2+). By decomposing the total bilayer electron density into different molecular groups, Zn(2+) and Ca(2+) were found to interact with the glycerol groups of the lipid molecules and cause minor swelling of the bilayers. Mg(2+) and Fe(2+) were found to position near the phosphate groups and cause a strong increase in the number of hydration water molecules. Our results present a molecular mechanism-of-action for the Hofmeister series in phospholipid membranes.
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Affiliation(s)
- Richard J Alsop
- Department of Physics and Astronomy, McMaster University, ABB-241, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada.
| | - Rafaëla Maria Schober
- Department of Physics and Astronomy, McMaster University, ABB-241, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada.
| | - Maikel C Rheinstädter
- Department of Physics and Astronomy, McMaster University, ABB-241, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada.
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50
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Lockhart C, Klimov DK. The Alzheimer's disease A β peptide binds to the anionic DMPS lipid bilayer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1118-28. [DOI: 10.1016/j.bbamem.2016.03.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 02/26/2016] [Accepted: 03/01/2016] [Indexed: 11/24/2022]
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