51
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Jones MR, Mu C, Wang MCP, Webb MI, Walsby CJ, Storr T. Modulation of the Aβ peptide aggregation pathway by KP1019 limits Aβ-associated neurotoxicity. Metallomics 2014; 7:129-35. [PMID: 25387614 DOI: 10.1039/c4mt00252k] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder that is increasing worldwide due to increased life expectancy. AD is characterized by two pathological hallmarks in the brain: amyloid-β (Aβ) plaque deposits and neurofibrillary tangles. A focus of AD research has concentrated on either inhibiting Aβ peptide aggregation that leads to plaque formation or breaking down pre-formed Aβ peptide aggregates. An alternative approach is to modulate the Aβ aggregation profile by facilitating the formation of Aβ species that are off-pathway and non-toxic. Herein, we report the re-purposing of the widely studied Ru(iii) anti-cancer complex KP1019, towards regulating the aggregation profile of the Aβ peptide. Using electron paramagnetic resonance (EPR) spectroscopy, we conclude that KP1019 binds to histidine residues, located at the N-terminus of the peptide, in a rapid and robust fashion. Native gels and transmission electron microscopy (TEM) analyses have provided insight into the species and structures that are generated by KP1019-Aβ interactions. Finally, incubation in an in vitro human neuronal cell model has demonstrated that the formation of KP1019-Aβ species rescues cell viability from Aβ-associated neurotoxicity. Modulation of the Aβ aggregation pathway via covalent interactions with small molecules is thus a promising AD therapeutic strategy.
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Affiliation(s)
- Michael R Jones
- Department of Chemistry, Simon Fraser University, Burnaby, BC V5A1S6, Canada.
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52
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Brinet D, Kaffy J, Oukacine F, Glumm S, Ongeri S, Taverna M. An improved capillary electrophoresis method for in vitro monitoring of the challenging early steps of Aβ1-42 peptide oligomerization: application to anti-Alzheimer's drug discovery. Electrophoresis 2014; 35:3302-9. [PMID: 25219962 DOI: 10.1002/elps.201400271] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 08/22/2014] [Accepted: 08/22/2014] [Indexed: 11/06/2022]
Abstract
We report an improved CE method to monitor in vitro the self-assembly of monomeric amyloid β-peptide (42 amino acids amyloid β-peptide, Aβ1-42 ) and in particular the crucial early steps involved in the formation of the neurotoxic oligomers. In order to start the kinetics from the beginning, sample preparation was optimized to provide samples containing exclusively the monomeric form. The CE method was also improved using a dynamic coating and by reducing the separation distance. Using this method, the disappearance of the monomer as well as the progressive formation of four species during the self-assembly process can now be monitored and quantified over time. The hydrodynamic radius of the species present at the initial kinetics step was estimated around 1.8 nm by Taylor dispersion analysis while SDS-PAGE analyses showed the predominance of the monomer. These results confirmed that the Aβ1-42 species present at this initial time was the monomer. Methylene blue, an anti-Alzheimer disease candidate, was then evaluated. In spite of an oligomerization inhibition, the enhanced disappearance of the Aβ1-42 monomer provoked by methylene blue was demonstrated for the first time. This method, allowing the monomeric and smallest oligomeric species to be monitored, represents a new accurate and precise way to evaluate compounds for drug discovery.
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Affiliation(s)
- Dimitri Brinet
- Protéines et Nanotechnologies en Sciences Séparatives, Institut Galien de Paris Sud, Faculté de Pharmacie, Université Paris-Sud, Châtenay-Malabry, France; Molécules Fluorées et Chimie Médicinale, Faculté de Pharmacie, Université Paris-Sud, Châtenay-Malabry, France
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53
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Kotler SA, Walsh P, Brender JR, Ramamoorthy A. Differences between amyloid-β aggregation in solution and on the membrane: insights into elucidation of the mechanistic details of Alzheimer's disease. Chem Soc Rev 2014; 43:6692-700. [PMID: 24464312 PMCID: PMC4110197 DOI: 10.1039/c3cs60431d] [Citation(s) in RCA: 301] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The association of the amyloid-β (Aβ) peptide with cellular membranes is hypothesized to be the underlying phenomenon of neurotoxicity in Alzheimer's disease. Misfolding of proteins and peptides, as is the case with Aβ, follows a progression from a monomeric state, through intermediates, ending at long, unbranched amyloid fibers. This tutorial review offers a perspective on the association of toxic Aβ structures with membranes as well as details of membrane-associated mechanisms of toxicity.
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Affiliation(s)
- Samuel A Kotler
- Biophysics and Department of Chemistry, University of Michigan, 930 N. University Ave, Ann Arbor, MI 48109-1055, USA.
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54
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Kaffy J, Brinet D, Soulier JL, Khemtémourian L, Lequin O, Taverna M, Crousse B, Ongeri S. Structure–activity relationships of sugar-based peptidomimetics as modulators of amyloid β-peptide early oligomerization and fibrillization. Eur J Med Chem 2014; 86:752-8. [DOI: 10.1016/j.ejmech.2014.09.031] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/05/2014] [Accepted: 09/08/2014] [Indexed: 12/19/2022]
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55
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Jia M, Wang M, Yang Y, Chen Y, Liu D, Wang X, Song L, Wu J, Yang Y. rAAV/ABAD-DP-6His attenuates oxidative stress-induced injury of PC12 cells. Neural Regen Res 2014; 9:481-8. [PMID: 25206842 PMCID: PMC4153500 DOI: 10.4103/1673-5374.130065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2014] [Indexed: 11/04/2022] Open
Abstract
Our previous studies have revealed that amyloid β (Aβ)-binding alcohol dehydrogenase (ABAD) decoy peptide antagonizes Aβ42-induced neurotoxicity. However, whether it improves oxidative stress injury remains unclear. In this study, a recombinant adenovirus constitutively secreting and expressing Aβ-ABAD decoy peptide (rAAV/ABAD-DP-6His) was successfully constructed. Our results showed that rAAV/ABAD-DP-6His increased superoxide dismutase activity in hydrogen peroxide-induced oxidative stress-mediated injury of PC12 cells. Moreover, rAAV/ABAD-DP-6His decreased malondialdehyde content, intracellular Ca(2+) concentration, and the level of reactive oxygen species. rAAV/ABAD-DP-6His maintained the stability of the mitochondrial membrane potential. In addition, the ATP level remained constant, and apoptosis was reduced. Overall, the results indicate that rAAV/ABAD-DP-6His generates the fusion peptide, Aβ-ABAD decoy peptide, which effectively protects PC12 cells from oxidative stress injury induced by hydrogen peroxide, thus exerting neuroprotective effects.
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Affiliation(s)
- Mingyue Jia
- Department of Neurology, the First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Mingyu Wang
- Department of Neurology, People's Hospital of Jilin Province, Changchun, Jilin Province, China
| | - Yi Yang
- Department of Neurology, the First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Yixin Chen
- Radioactive Medicine Specialty, College of Public Health in Jilin University, Changchun, Jilin Province, China
| | - Dujuan Liu
- Department of Burn and Plastic Surgery, the General Hospital of CNPC in Jilin, Jilin, Jilin Province, China
| | - Xu Wang
- Department of Neurology, the First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Lei Song
- Department of Neurology, the First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Jiang Wu
- Department of Neurology, the First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Yu Yang
- Department of Neurology, the First Hospital of Jilin University, Changchun, Jilin Province, China
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56
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Gillman AL, Jang H, Lee J, Ramachandran S, Kagan B, Nussinov R, Teran Arce F. Activity and architecture of pyroglutamate-modified amyloid-β (AβpE3-42) pores. J Phys Chem B 2014; 118:7335-44. [PMID: 24922585 PMCID: PMC4096221 DOI: 10.1021/jp5040954] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Revised: 06/10/2014] [Indexed: 12/17/2022]
Abstract
Among the family of Aβ peptides, pyroglutamate-modified Aβ (AβpE) peptides are particularly associated with cytotoxicity in Alzheimer's disease (AD). They represent the dominant fraction of Aβ oligomers in the brains of AD patients, but their accumulation in the brains of elderly individuals with normal cognition is significantly lower. Accumulation of AβpE plaques precedes the formation of plaques of full-length Aβ (Aβ1-40/42). Most of these properties appear to be associated with the higher hydrophobicity of AβpE as well as an increased resistance to enzymatic degradation. However, the important question of whether AβpE peptides induce pore activity in lipid membranes and their potential toxicity compared with other Aβ pores is still open. Here we examine the activity of AβpE pores in anionic membranes using planar bilayer electrical recording and provide their structures using molecular dynamics simulations. We find that AβpE pores spontaneously induce ionic current across the membrane and have some similar properties to the other previously studied pores of the Aβ family. However, there are also some significant differences. The onset of AβpE3-42 pore activity is generally delayed compared with Aβ1-42 pores. However, once formed, AβpE3-42 pores produce increased ion permeability of the membrane, as indicated by a greater occurrence of higher conductance electrical events. Structurally, the lactam ring of AβpE peptides induces a change in the conformation of the N-terminal strands of the AβpE3-42 pores. While the N-termini of wild-type Aβ1-42 peptides normally reside in the bulk water region, the N-termini of AβpE3-42 peptides tend to reside in the hydrophobic lipid core. These studies provide a first step to an understanding of the enhanced toxicity attributed to AβpE peptides.
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Affiliation(s)
- Alan L. Gillman
- Department
of Bioengineering, University of California,
San Diego, 9500 Gilman
Drive, La Jolla, California 92093, United States
| | - Hyunbum Jang
- Cancer
and Inflammation Program, National Cancer Institute at Frederick,
Leidos Biomedical Research, Inc., Frederick
National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
| | - Joon Lee
- Department
of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Srinivasan Ramachandran
- Department
of Bioengineering, University of California,
San Diego, 9500 Gilman
Drive, La Jolla, California 92093, United States
- Department
of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Bruce
L. Kagan
- Department
of Psychiatry, David Geffen School of Medicine, Semel Institute for
Neuroscience and Human Behavior, University
of California, 760 Westwood
Plaza, Los Angeles, California 90024, United States
| | - Ruth Nussinov
- Cancer
and Inflammation Program, National Cancer Institute at Frederick,
Leidos Biomedical Research, Inc., Frederick
National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
- Department
of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Fernando Teran Arce
- Department
of Bioengineering, University of California,
San Diego, 9500 Gilman
Drive, La Jolla, California 92093, United States
- Department
of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
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57
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Probing the interplay between amyloidogenic proteins and membranes using lipid monolayers and bilayers. Adv Colloid Interface Sci 2014; 207:81-92. [PMID: 24200086 DOI: 10.1016/j.cis.2013.10.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 10/11/2013] [Accepted: 10/13/2013] [Indexed: 11/21/2022]
Abstract
Many degenerative diseases such as Alzheimer's and Parkinson's involve proteins that have a tendency to misfold and aggregate eventually forming amyloid fibers. This review describes the use of monolayers, bilayers, supported membranes, and vesicles as model systems that have helped elucidate the mechanisms and consequences of the interactions between amyloidogenic proteins and membranes. These are twofold: membranes favor the formation of amyloid structures and these induce damage in those membranes. We describe studies that show how interfaces, especially charged ones, favor amyloidogenic protein aggregation by several means. First, surfaces increase the effective protein concentration reducing a three-dimensional system to a two-dimensional one. Second, charged surfaces allow electrostatic interactions with the protein. Anionic lipids as well as rafts, rich in cholesterol and gangliosides, prove to play an especially important role. Finally, these amphipathic systems also offer a hydrophobic environment favoring conformational changes, oligomerization, and eventual formation of mature fibers. In addition, we examine several models for membrane permeabilization: protein pores, leakage induced by extraction of lipids, chaotic pores, and membrane tension, presenting illustrative examples of experimental evidence in support of these models. The picture that emerges from recent work is one where more than one mechanism is in play. Which mechanism prevails depends on the protein, its aggregation state, and the lipid environment in which the interactions occur.
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58
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Xu PX, Wang SW, Yu XL, Su YJ, Wang T, Zhou WW, Zhang H, Wang YJ, Liu RT. Rutin improves spatial memory in Alzheimer's disease transgenic mice by reducing Aβ oligomer level and attenuating oxidative stress and neuroinflammation. Behav Brain Res 2014; 264:173-80. [PMID: 24512768 DOI: 10.1016/j.bbr.2014.02.002] [Citation(s) in RCA: 165] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Revised: 01/30/2014] [Accepted: 02/01/2014] [Indexed: 12/22/2022]
Abstract
Alzheimer's disease (AD) is a progressive, neurodegenerative disease characterized by extracellular β-amyloid (Aβ) plaques and intracellular neurofibrillary tangles in the brain. Aβ aggregation is closely associated with neurotoxicity, oxidative stress, and neuronal inflammation. The soluble Aβ oligomers are believed to be the most neurotoxic form among all forms of Aβ aggregates. We have previously reported a polyphenol compound rutin that could inhibit Aβ aggregation and cytotoxicity, attenuate oxidative stress, and decrease the production of nitric oxide and proinflammatory cytokines in vitro. In the current study, we investigated the effect of rutin on APPswe/PS1dE9 transgenic mice. Results demonstrated that orally administered rutin significantly attenuated memory deficits in AD transgenic mice, decreased oligomeric Aβ level, increased super oxide dismutase (SOD) activity and glutathione (GSH)/glutathione disulfide (GSSG) ratio, reduced GSSG and malondialdehyde (MDA) levels, downregulated microgliosis and astrocytosis, and decreased interleukin (IL)-1β and IL-6 levels in the brain. These results indicated that rutin is a promising agent for AD treatment because of its antioxidant, anti-inflammatory, and reducing Aβ oligomer activities.
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Affiliation(s)
- Peng-Xin Xu
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China; School of Life Science, Ningxia University, Yinchuan 750021, China
| | - Shao-Wei Wang
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiao-Lin Yu
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Ya-Jing Su
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China; School of Life Science, Ningxia University, Yinchuan 750021, China
| | - Teng Wang
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Wei-Wei Zhou
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - He Zhang
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Yu-Jiong Wang
- School of Life Science, Ningxia University, Yinchuan 750021, China.
| | - Rui-Tian Liu
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
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59
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Relini A, Marano N, Gliozzi A. Misfolding of amyloidogenic proteins and their interactions with membranes. Biomolecules 2013; 4:20-55. [PMID: 24970204 PMCID: PMC4030986 DOI: 10.3390/biom4010020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 12/13/2013] [Accepted: 12/17/2013] [Indexed: 01/07/2023] Open
Abstract
In this paper, we discuss amyloidogenic proteins, their misfolding, resulting structures, and interactions with membranes, which lead to membrane damage and subsequent cell death. Many of these proteins are implicated in serious illnesses such as Alzheimer’s disease and Parkinson’s disease. Misfolding of amyloidogenic proteins leads to the formation of polymorphic oligomers and fibrils. Oligomeric aggregates are widely thought to be the toxic species, however, fibrils also play a role in membrane damage. We focus on the structure of these aggregates and their interactions with model membranes. Study of interactions of amlyoidogenic proteins with model and natural membranes has shown the importance of the lipid bilayer in protein misfolding and aggregation and has led to the development of several models for membrane permeabilization by the resulting amyloid aggregates. We discuss several of these models: formation of structured pores by misfolded amyloidogenic proteins, extraction of lipids, interactions with receptors in biological membranes, and membrane destabilization by amyloid aggregates perhaps analogous to that caused by antimicrobial peptides.
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Affiliation(s)
- Annalisa Relini
- Department of Physics, University of Genoa, Genoa 16146, Italy.
| | - Nadia Marano
- Department of Physics, University of Genoa, Genoa 16146, Italy.
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60
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Thinnes FP. Concerning a Clue on the Enigma of “Amyloid Made” versus “Amyloid Regulated” Channels in Cell Membranes: A Comment on M. A. Mukhamedyarov et al., Neuroscience and Behavioral Physiology, Vol. 43, No. 4, pp. 479–484 (2013). ACTA ACUST UNITED AC 2013. [DOI: 10.1007/s11055-013-9884-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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61
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Guerrero-Muñoz MJ, Castillo-Carranza DL, Sengupta U, White MA, Kayed R. Design of metastable β-sheet oligomers from natively unstructured peptide. ACS Chem Neurosci 2013; 4:1520-3. [PMID: 24106878 DOI: 10.1021/cn4001395] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Amyloid oligomers represent the primary pathological species for neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Toxic oligomers are formed by many different proteins and peptides, but their polydispersity makes them highly dynamic and heterogeneous. One way to stabilize these structures is to prepare constrained peptides that can be used to study amyloid intermediates, to identify oligomer-specific drugs, and to generate conformational antibodies. These conformational antibodies have demonstrated that oligomers share a common epitope. In this research, we used a 40-amino acid unstructured segment of prion protein (Prp) 109-148 with substitutions of methionine for glycine (Prp-G) residues to prepare a stable and homogeneous population of β-sheet oligomer mimics. These structures were characterized by multiple biophysical and biochemical techniques that show characteristic features of oligomers. Finally, this preparation was not detected by three different sequence dependent prion antibodies.
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Affiliation(s)
- Marcos J. Guerrero-Muñoz
- Department of Neurology, the George P. and
Cynthia Woods Mitchell Center for Neurodegenerative Diseases, ‡Departments of Biochemistry
and Molecular Biology, the Sealy Center for
Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Diana L. Castillo-Carranza
- Department of Neurology, the George P. and
Cynthia Woods Mitchell Center for Neurodegenerative Diseases, ‡Departments of Biochemistry
and Molecular Biology, the Sealy Center for
Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Urmi Sengupta
- Department of Neurology, the George P. and
Cynthia Woods Mitchell Center for Neurodegenerative Diseases, ‡Departments of Biochemistry
and Molecular Biology, the Sealy Center for
Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Mark A. White
- Department of Neurology, the George P. and
Cynthia Woods Mitchell Center for Neurodegenerative Diseases, ‡Departments of Biochemistry
and Molecular Biology, the Sealy Center for
Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Rakez Kayed
- Department of Neurology, the George P. and
Cynthia Woods Mitchell Center for Neurodegenerative Diseases, ‡Departments of Biochemistry
and Molecular Biology, the Sealy Center for
Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555, United States
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62
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Hayden EY, Teplow DB. Amyloid β-protein oligomers and Alzheimer's disease. ALZHEIMERS RESEARCH & THERAPY 2013; 5:60. [PMID: 24289820 PMCID: PMC3978746 DOI: 10.1186/alzrt226] [Citation(s) in RCA: 184] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The oligomer cascade hypothesis, which states that oligomers are the initiating pathologic agents in Alzheimer’s disease, has all but supplanted the amyloid cascade hypothesis, which suggested that fibers were the key etiologic agents in Alzheimer’s disease. We review here the results of in vivo, in vitro and in silico studies of amyloid β-protein oligomers, and discuss important caveats that should be considered in the evaluation of these results. This article is divided into four sections that mirror the main approaches used in the field to better understand oligomers: (1) attempts to locate and examine oligomers in vivo in situ; that is, without removing these species from their environment; (2) studies involving oligomers extracted from human or animal tissues and the subsequent characterization of their properties ex vivo; (3) studies of oligomers that have been produced synthetically and studied using a reductionist approach in relatively simple in vitro biophysical systems; and (4) computational studies of oligomers in silico. These multiple orthogonal approaches have revealed much about the molecular and cell biology of amyloid β-protein. However, as informative as these approaches have been, the amyloid β-protein oligomer system remains enigmatic.
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Affiliation(s)
- Eric Y Hayden
- Department of Neurology, 635 Charles E. Young Drive South, Room 455, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - David B Teplow
- Department of Neurology, 635 Charles E. Young Drive South, Room 455, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA ; Brain Research and Molecular Biology Institutes, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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63
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Camilleri A, Zarb C, Caruana M, Ostermeier U, Ghio S, Högen T, Schmidt F, Giese A, Vassallo N. Mitochondrial membrane permeabilisation by amyloid aggregates and protection by polyphenols. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2532-43. [PMID: 23817009 DOI: 10.1016/j.bbamem.2013.06.026] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 06/17/2013] [Accepted: 06/19/2013] [Indexed: 12/20/2022]
Abstract
Alzheimer's disease and Parkinson's disease are neurodegenerative disorders characterised by the misfolding of proteins into soluble prefibrillar aggregates. These aggregate complexes disrupt mitochondrial function, initiating a pathophysiological cascade leading to synaptic and neuronal degeneration. In order to explore the interaction of amyloid aggregates with mitochondrial membranes, we made use of two in vitro model systems, namely: (i) lipid vesicles with defined membrane compositions that mimic those of mitochondrial membranes, and (ii) respiring mitochondria isolated from neuronal SH-SY5Y cells. External application of soluble prefibrillar forms, but not monomers, of amyloid-beta (Aβ42 peptide), wild-type α-synuclein (α-syn), mutant α-syn (A30P and A53T) and tau-441 proteins induced a robust permeabilisation of mitochondrial-like vesicles, and triggered cytochrome c release (CCR) from isolated mitochondrial organelles. Importantly, the effect on mitochondria was shown to be dependent upon cardiolipin, an anionic phospholipid unique to mitochondria and a well-known key player in mitochondrial apoptosis. Pharmacological modulators of mitochondrial ion channels failed to inhibit CCR. Thus, we propose a generic mechanism of thrilling mitochondria in which soluble amyloid aggregates have the intrinsic capacity to permeabilise mitochondrial membranes, without the need of any other protein. Finally, six small-molecule compounds and black tea extract were tested for their ability to inhibit permeation of mitochondrial membranes by Aβ42, α-syn and tau aggregate complexes. We found that black tea extract and rosmarinic acid were the most potent mito-protectants, and may thus represent important drug leads to alleviate mitochondrial dysfunction in neurodegenerative diseases.
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Affiliation(s)
- Angelique Camilleri
- Department of Physiology and Biochemistry, University of Malta, Msida, Malta
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64
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Jang H, Connelly L, Arce FT, Ramachandran S, Lal R, Kagan BL, Nussinov R. Alzheimer's disease: which type of amyloid-preventing drug agents to employ? Phys Chem Chem Phys 2013; 15:8868-77. [PMID: 23450150 PMCID: PMC3663909 DOI: 10.1039/c3cp00017f] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The current paradigm in the amyloid hypothesis brands small β-amyloid (Aβ) oligomers as the toxic species in Alzheimer's disease (AD). These oligomers are fibril-like; contain β-sheet structure, and present exposed hydrophobic surface. Oligomers with this motif are capable of penetrating the cell membrane, gathering to form toxic ion channels. Current agents suppressing precursor Aβ cleavage have only met partial success; and to date, those targeting the peptides and their assemblies in the aqueous environment of the extracellular space largely fail in clinical trials. One possible reason is failure to reach membrane-embedded targets of disease-'infected' cells. Here we provide an overview, point to the need to account for the lipid environment when aiming to prevent the formation of toxic channels, and propose a combination therapy to target the species spectrum.
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Affiliation(s)
- Hyunbum Jang
- Center for Cancer Research, Nanobiology Program, Basic Science Program, SAIC-Frederick, Inc., National Cancer Institute, Frederick, Maryland 21702, USA
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65
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Ochoa-de la Paz LD, Salazar-Soto DB, Reyes JP, Miledi R, Martinez-Torres A. A hyperpolarization-activated ion current of amphibian oocytes. Pflugers Arch 2013; 465:1087-99. [PMID: 23440457 DOI: 10.1007/s00424-013-1231-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Revised: 01/28/2013] [Accepted: 01/30/2013] [Indexed: 11/29/2022]
Abstract
A comparative analysis of a hyperpolarization-activated ion current present in amphibian oocytes was performed using the two-electrode voltage-clamp technique in Xenopus laevis, Xenopus tropicalis, and Ambystoma mexicanum. This current appears to be driven mainly by Cl(-) ions, is independent of Ca(2+), and is made evident by applying extremely negative voltage pulses; it shows a slow activating phase and little or no desensitization. The pharmacological profile of the current is complex. The different channel blocker used for Cl(-), K(+), Na(+) and Ca(2+) conductances, exhibited various degrees of inhibition depending of the species. The profiles illustrate the intricacy of the components that give rise to this current. During X. laevis oogenesis, the hyperpolarization-activated current is present at all stages of oocytes tested (II-VI), and the amplitude of the current increases from about 50 nA in stage I to more than 1 μA in stage VI; nevertheless, there was no apparent modification of the kinetics. Our results suggest that the hyperpolarization-activated current is present both in order Anura and Urodela oocytes. However, the electrophysiological and pharmacological characteristics are quite perplexing and seem to suggest a mixture of ionic conductances that includes the activation of both anionic and cationic channels, most probably transiently opened due to the extreme hyperpolarizion of the plasma membrane. As a possible mechanism for the generation of the current, a kinetic model which fits the data suggests the opening of pores in the plasma membrane whose ion selectivity is dependent on the extracellular Cl(-) concentration. The extreme voltage conditions could induce the opening of otherwise latent pores in plasma membrane proteins (i.e., carriers), resembling the ´slippage´ events already described for some carriers. These observations should be valuable for other groups trying to express cloned, voltage-dependent ion channels in oocytes of amphibian in which hyperpolarizing voltage pulses are applied to activate the channels.
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Affiliation(s)
- L D Ochoa-de la Paz
- Departamento de Neurobiología Celular y Molecular, Laboratorio de Neurobiología Molecular y Celular, Instituto de Neurobiología, Campus UNAM Juriquilla, Querétaro, Qro, CP 76230, Mexico.
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Jang H, Connelly L, Arce FT, Ramachandran S, Kagan BL, Lal R, Nussinov R. Mechanisms for the Insertion of Toxic, Fibril-like β-Amyloid Oligomers into the Membrane. J Chem Theory Comput 2013; 9:822-833. [PMID: 23316126 PMCID: PMC3539805 DOI: 10.1021/ct300916f] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Amyloid-β (Aβ) oligomers destabilize cellular ionic homeostasis, mediating Alzheimer's disease (AD). It is still unclear whether the mechanism (i) is mediated by cell surface receptors; (ii) is direct, with Aβ oligomers interacting with membrane lipids; or (iii) both mechanisms take place. Recent studies indicate that Aβ oligomers may act by either of the last two. Little is known about the oligomers' structures and how they spontaneously insert into the membrane. Using explicit solvent molecular dynamics (MD) simulations, we show that fibril-like Aβ(17-42) (p3) oligomer is capable of penetrating the membrane. Insertion is similar to that observed for protegrin-1 (PG-1), a cytolytic β-sheet-rich antimicrobial peptide (AMP). Both Aβ and PG-1 favor the amphipathic interface of the lipid bilayer in the early stage of interaction with the membrane. U-shaped Aβ oligomers are observed in solution and in the membrane, suggesting that the preformed seeds can be shared by amyloid fibrils in the growth phase and membrane toxicity. Here we provide sequential events in possible Aβ oligomer membrane-insertion pathways. We speculate that for the U-shaped motif, a trimer is the minimal oligomer size to insert effectively. We propose that monomers and dimers may insert in (apparently on-pathway) aggregation-intermediate β-hairpin state, and may (or may not) convert to a U-shape in the bilayer. Together with earlier observations, our results point to a non-specific, broadly heterogeneous landscape of membrane-inserting oligomer conformations, pathways, and membrane-mediated toxicity of β-rich oligomers.
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Affiliation(s)
- Hyunbum Jang
- Basic Science Program, SAIC-Frederick, Inc., Center for Cancer Research Nanobiology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, USA
| | - Laura Connelly
- Departments of Bioengineering and of Mechanical and Aerospace Engineering, and Materials Science Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Fernando Teran Arce
- Departments of Bioengineering and of Mechanical and Aerospace Engineering, and Materials Science Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Srinivasan Ramachandran
- Departments of Bioengineering and of Mechanical and Aerospace Engineering, and Materials Science Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Bruce L. Kagan
- Department of Psychiatry, David Geffen School of Medicine, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, California 90024, USA
| | - Ratnesh Lal
- Departments of Bioengineering and of Mechanical and Aerospace Engineering, and Materials Science Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Ruth Nussinov
- Basic Science Program, SAIC-Frederick, Inc., Center for Cancer Research Nanobiology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, USA
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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