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Amyloid oligomers

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https://www.readbyqxmd.com/read/28624352/pressure-effects-on-%C3%AE-synuclein-amyloid-fibrils-an-experimental-investigation-on-their-dissociation-and-reversible-nature
#1
Federica Piccirilli, Nicoletta Plotegher, Francesco Spinozzi, Luigi Bubacco, Paolo Mariani, Mariano Beltramini, Isabella Tessari, Valeria Militello, Andrea Perucchi, Heinz Wilfried Amenitsch, Enrico Baldassarri, Milos Steinhart, Stefano Lupi, Maria Grazia Ortore
α-synuclein amyloid fibrils are found in surviving neurons of Parkinson's disease affected patients, but the role they play in the disease development is still under debate. A growing number of evidences points to soluble oligomers as the major cytotoxic species, while insoluble fibrillar aggregates could even play a protection role. In this work, we investigate α-synuclein fibrils dissociation induced at high pressure by means of Small Angle X-ray Scattering and Fourier Transform Infrared Spectroscopy. Fibrils were produced from wild type α-synuclein and two familial mutants, A30P and A53T...
June 14, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28623460/spreading-of-pathology-in-alzheimer-s-disease
#2
REVIEW
Zhong-Yue Lv, Chen-Chen Tan, Jin-Tai Yu, Lan Tan
The senile plaques (SPs) and neurofibrillary tangles (NFTs) are the two major pathological hallmarks of AD, which are composed of β-amyloid protein and Tau protein. So the β-amyloid protein (Aβ) and Tau oligomers (oTau) are the majority in the pathology of AD. Recently, the spreading of Aβ and oTau in the brain of AD patients has received heated value. In this review, we summarize recent research progress and aim to figure out the spreading mechanism of Aβ and Tau in AD via introduction of the formation, release, uptake, diffusion between different brain regions, and the propagation principle of Aβ and Tau...
June 16, 2017: Neurotoxicity Research
https://www.readbyqxmd.com/read/28623233/structural-and-functional-analyses-of-pyroglutamate-amyloid-%C3%AE-specific-antibodies-as-a-basis-for-alzheimer-immunotherapy
#3
Anke Piechotta, Christoph Parthier, Martin Kleinschmidt, Kathrin Gnoth, Thierry Pillot, Inge Lues, Hans-Ulrich Demuth, Stephan Schilling, Jens-Ulrich Rahfeld, Milton T Stubbs
Alzheimers disease is associated with deposition of the amyloidogenic peptide Aβ in the brain. Passive immunization using Aβ-specific antibodies has been demonstrated to reduce amyloid deposition both in vitro and in vivo. As N terminally truncated pyroglutamate (pE)-modified Aβ species (AβpE3) exhibit enhanced aggregation potential and propensity to form toxic oligomers, they represent particularly attractive targets for antibody therapy. Here we present three separate monoclonal antibodies that specifically recognize AβpE3 with affinities of 1-10 nM and inhibit AβpE3 fibril formation in vitro...
June 16, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28621364/single-molecule-probing-of-amyloid-nano-ensembles-using-the-polymer-nanoarray-approach
#4
Sibaprasad Maity, Ekaterina Viazovkina, Alexander Gall, Yuri L Lyubchenko
Soluble amyloid-beta (Aβ) oligomers are the prime causative agents of cognitive deficits during early stages of Alzheimer's disease (AD). The transient nature of the oligomers makes them difficult to characterize by traditional techniques, suggesting that advanced approaches are necessary. Previously developed fluorescence-based tethered approach for probing intermolecular interactions (TAPIN) and AFM-based single-molecule force spectroscopy are capable of probing dimers of Aβ peptides. In this paper, a novel polymer nanoarray approach to probe trimers and tetramers formed by the Aβ(14-23) segment of Aβ protein at the single-molecule level is applied...
June 16, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28620147/prostaglandin-i2-is-responsible-for-ameliorating-prostaglandin-e2-stress-in-stimulating-the-expression-of-tumor-necrosis-factor-%C3%AE-in-a-%C3%AE-amyloid-protein-dependent-mechanism
#5
Shao-Qin Zheng, Zi-Yi Gong, Chen-Di Lu, Pu Wang
Cyclooxygenase-2 (COX-2) has been found to be induced during the early stage of Alzheimer's disease (AD). Using mouse-derived astrocyte and APP/PS1 transgenic (Tg) mice as model systems, we firstly elucidated the mechanisms underlying COX-2 metabolic production including prostaglandin (PG)E2- and PGI2-mediated tumor necrosis factor α (TNF-α) regulation. Specifically, PGE2 accumulation in astrocyte activated the p38 and JNK/c-Jun signaling pathways via phosphorylation, resulting in TNF-α expression. In contrast, the administration of PGI2 attenuated the effects of PGE2 in stimulating the production of TNF-α by inhibiting the activity of TNF-α promoter and the binding activity of AP1 on the promoter of TNF-α...
June 13, 2017: Oncotarget
https://www.readbyqxmd.com/read/28613069/molybdenum-disulfide-nanoparticles-as-multifunctional-inhibitors-against-alzheimer-s-disease
#6
Qiusen Han, Shuangfei Cai, Lin Yang, Xinhuan Wang, Cui Qi, Rong Yang, Chen Wang
The complex pathogenic mechanisms of Alzheimer's disease (AD) include the aggregation of β-amyloid peptides (Aβ) into oligomers or fibrils as well as Aβ-mediated oxidative stress, which require comprehensive treatment. Therefore, the inhibition of Aβ aggregation and free-radical scavenging are essential for the treatment of AD. Nanoparticles (NPs) have been found to influence Aβ aggregation process in vitro. Herein, we report the inhibition effects of molybdenum disulfide (MoS2) NPs on Aβ aggregation...
June 14, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28607171/astrocyte-transforming-growth-factor-beta-1-protects-synapses-against-a%C3%AE-oligomers-in-alzheimer-s-disease-model
#7
Luan Pereira Diniz, Vanessa Tortelli, Isadora Matias, Juliana Morgado, Ana Paula Bérgamo Araujo, Helen M Melo, Gisele S Seixas da Silva, Soniza V Alves-Leon, Jorge M de Souza, Sergio T Ferreira, Fernanda G De Felice, Flávia Carvalho Alcantara Gomes
Alzheimer's disease (AD) is characterized by progressive cognitive decline, increasingly attributed to neuronal dysfunction induced by amyloid-β oligomers (AβOs). Although the impact of AβOs on neurons has been extensively studied, only recently have the possible effects of AβOs on astrocytes begun to be investigated. Given the key roles of astrocytes in synapse formation, plasticity and function, we sought to investigate the impact of AβOs on astrocytes, and to determine if this impact is related to the deleterious actions of AβOs on synapses...
June 8, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28595357/the-alzheimer-s-disease-transcriptome-mimics-the-neuroprotective-signature-of-igf-1-receptor-deficient-neurons
#8
Caroline George, Géraldine Gontier, Philippe Lacube, Jean-Christophe François, Martin Holzenberger, Saba Aïd
Seminal studies using post-mortem brains of patients with Alzheimer's disease evidenced aberrant insulin-like growth factor 1 receptor (IGF1R) signalling. Addressing causality, work in animal models recently demonstrated that long-term suppression of IGF1R signalling alleviates Alzheimer's disease progression and promotes neuroprotection. However, the underlying mechanisms remain largely elusive. Here, we showed that genetically ablating IGF1R in neurons of the ageing brain efficiently protects from neuroinflammation, anxiety and memory impairments induced by intracerebroventricular injection of amyloid-β oligomers...
June 8, 2017: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/28592267/a-vaccine-with-a%C3%AE-oligomer-specific-mimotope-attenuates-cognitive-deficits-and-brain-pathologies-in-transgenic-mice-with-alzheimer-s-disease
#9
Shao-Wei Wang, Dong-Qun Liu, Ling-Xiao Zhang, Mei Ji, Yang-Xin Zhang, Quan-Xiu Dong, Shu-Ying Liu, Xi-Xiu Xie, Rui-Tian Liu
BACKGROUND: β-Amyloid peptide (Aβ) oligomers are initial factors used to induce Alzheimer's disease (AD) development, and Aβ monomers have normal physiological function. The antibodies or vaccines against Aβ monomers have serious problems, such as side effects and low curative effects. Therefore, it is essential to specifically target Aβ oligomers rather than monomers for the treatment of AD. METHODS: The mimotopes of Aβ oligomers were obtained by panning the phage-displayed random peptide libraries using oligomer-specific antibodies as targets and expressed on the surface of EBY100 Saccharomyces cerevisiae to generate yeast cell base vaccines...
June 7, 2017: Alzheimer's Research & Therapy
https://www.readbyqxmd.com/read/28587858/rebamipide-reduces-amyloid-%C3%AE-1-42-a%C3%AE-42-production-and-ameliorates-a%C3%AE-43-lowered-cell-viability-in-cultured-sh-sy5y-human-neuroblastoma-cells
#10
Kenta Fukui, Kazuma Yachi, Hidemi Yoshida, Kunikazu Tanji, Tomoh Matsumiya, Ryo Hayakari, Kazushi Tsuruga, Hiroshi Tanaka, Tadaatsu Imaizumi
Amyloid-beta (Aβ) peptides, Aβ 1-42 (Aβ42) and Aβ43, in particular, have been implicated in the pathophysiology of neurodegenerative disease such as Alzheimer's disease (AD). Rebamipide (REB), a gastrointestinal protective drug, can cross the blood-brain barrier after oral administration; however, the effects of REB on neuronal cells have not yet been reported. In this study, we investigated the effects of REB on Aβ43-induced cytotoxicity (monomers, 10μM) in cultured SH-SY5Y human neuroblastoma cells...
June 3, 2017: Neuroscience Research
https://www.readbyqxmd.com/read/28587777/effect-of-ionic-strength-on-the-aggregation-kinetics-of-the-amidated-amyloid-beta-peptide-a%C3%AE-1-40-in-aqueous-solutions
#11
Adriana Campos-Ramírez, Maripaz Márquez, Liliana Quintanar, Luis F Rojas-Ochoa
In this work we study the effect of solution ionic strength on the structural evolution of amidated amyloid beta peptide Aβ (1-40) oligomers at the early stages of fibril formation. By light scattering, we follow the time evolution of the structure and short-time dynamics of peptide structures at low ionic strengths. Our results allow identifying initial oligomer structures as the effective building blocks in the amyloid fibrils formation and indicate that the oligomers growth pathway, from compact structures to flexible chain-like structures, becomes faster as the solution ionic strength is increased...
May 19, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28585804/membrane-interactions-of-hiapp-monomer-and-oligomer-with-lipid-membranes-by-molecular-dynamics-simulations
#12
Mingzhen Zhang, Baiping Ren, Yonglan Liu, Guizhao Liang, Yan Sun, Lijian Xu, Jie Zheng
Interaction of human islet amyloid polypeptide (hIAPP) peptides with cell membrane is crucial for the understanding of amyloid toxicity associated with Type II diabetes (T2D). While it is known that the hIAPP-membrane interactions are considered to promote hIAPP aggregation into fibrils and induce membrane disruption, the membrane-induced conformation, orientation, aggregation, and adsorption behaviors of hIAPP peptides have not been well understood at atomic level. Herein, we perform all-atom explicit-water molecular dynamics (MD) simulations to study the adsorption, orientation, and surface interaction of hIAPP aggregates with different sizes (monomer to tetramer) and conformations (monomer with α-helix and tetramer with β-sheet-rich U-turn) upon adsorption on the lipid bilayers composed of both pure zwitterionic POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and mixed anionic POPC/POPE (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine) (3:1) lipids...
June 6, 2017: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/28584111/phage-display-and-kinetic-selection-of-antibodies-that-specifically-inhibit-amyloid-self-replication
#13
Anna Munke, Jonas Persson, Tanja Weiffert, Erwin De Genst, Georg Meisl, Paolo Arosio, Anna Carnerup, Christopher M Dobson, Michele Vendruscolo, Tuomas P J Knowles, Sara Linse
The aggregation of the amyloid β peptide (Aβ) into amyloid fibrils is a defining characteristic of Alzheimer's disease. Because of the complexity of this aggregation process, effective therapeutic inhibitors will need to target the specific microscopic steps that lead to the production of neurotoxic species. We introduce a strategy for generating fibril-specific antibodies that selectively suppress fibril-dependent secondary nucleation of the 42-residue form of Aβ (Aβ42). We target this step because it has been shown to produce the majority of neurotoxic species during aggregation of Aβ42...
June 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28581708/optimization-of-d-peptides-for-a%C3%AE-monomer-binding-specificity-enhances-their-potential-to-eliminate-toxic-a%C3%AE-oligomers
#14
Antonia Nicole Klein, Tamar Ziehm, Thomas van Groen, Inga Kadish, Anne Elfgen, Markus Tusche, Maren Thomaier, Kerstin Reiss, Oleksandr Brener, Lothar Gremer, Janine Kutzsche, Dieter Willbold
Amyloid-beta (Aβ) oligomers are thought to be causative for the development and progression of Alzheimer's disease (AD). Starting from the Aβ oligomer eliminating D-enantiomeric peptide D3, we developed and applied a two-step procedure based on peptide microarrays to identify D3 derivatives with increased binding affinity and specificity for monomeric Aβ(1-42) to further enhance the Aβ oligomer elimination efficacy. Out of more than 1,000 D3 derivatives, we selected seven novel D-peptides, named ANK1 to ANK7, and characterized them in more detail in vitro...
June 5, 2017: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/28564579/lipid-membranes-catalyse-the-fibril-formation-of-the-amyloid-%C3%AE-1-42-peptide-through-lipid-fibril-interactions-that-reinforce-secondary-pathways
#15
David J Lindberg, Emelie Wesén, Johan Björkeroth, Sandra Rocha, Elin K Esbjörner
Alzheimer's disease is associated with the aggregation of amyloid-β (Aβ) peptides into oligomers and fibrils. Herein we explore how model lipid membranes modulate the rate and mechanisms of Aβ(1-42) self-assembly, in order to shed light on how this pathological reaction, may occur in the lipid-rich environments that this peptide encounters in the brain. Using a combination of in vitro biophysical experiments and theoretical approaches, we show that zwitterionic lipid vesicles accelerate the Aβ(1-42) fibril growth rate by interacting specifically with the growing fibrils...
May 28, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28562630/the-influence-of-n-terminal-acetylation-on-micelle-induced-conformational-changes-and-aggregation-of-%C3%AE-synuclein
#16
David Ruzafa, Yuriko S Hernandez-Gomez, Giovanni Bisello, Kerensa Broersen, Bertrand Morel, Francisco Conejero-Lara
The biological function of α-Synuclein has been related to binding to lipids and membranes but these interactions can also mediate α-Synuclein aggregation, which is associated to Parkinson's disease and other neuropathologies. In brain tissue α-Synuclein is constitutively N-acetylated, a modification that plays an important role in its conformational propensity, lipid and membrane binding, and aggregation propensity. We studied the interactions of the lipid-mimetic SDS with N-acetylated and non-acetylated α-Synuclein, as well as their early-onset Parkinson's disease variants A30P, E46K and A53T...
2017: PloS One
https://www.readbyqxmd.com/read/28559794/possible-function-of-molecular-chaperones-in-diseases-caused-by-propagating-amyloid-aggregates
#17
REVIEW
Vladimir F Lazarev, Elena R Mikhaylova, Irina V Guzhova, Boris A Margulis
The vast majority of neurodegenerative pathologies stem from the formation of toxic oligomers and aggregates composed of wrongly folded proteins. These protein complexes can be released from pathogenic cells and enthralled by other cells, causing the formation of new aggregates in a prion-like manner. By this mechanism, migrating complexes can transmit a disorder to distant regions of the brain and promote gradually transmitting degenerative processes. Molecular chaperones can counteract the toxicity of misfolded proteins...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28559789/the-hsp70-hsp90-chaperone-machinery-in-neurodegenerative-diseases
#18
REVIEW
Rachel E Lackie, Andrzej Maciejewski, Valeriy G Ostapchenko, Jose Marques-Lopes, Wing-Yiu Choy, Martin L Duennwald, Vania F Prado, Marco A M Prado
The accumulation of misfolded proteins in the human brain is one of the critical features of many neurodegenerative diseases, including Alzheimer's disease (AD). Assembles of beta-amyloid (Aβ) peptide-either soluble (oligomers) or insoluble (plaques) and of tau protein, which form neurofibrillary tangles, are the major hallmarks of AD. Chaperones and co-chaperones regulate protein folding and client maturation, but they also target misfolded or aggregated proteins for refolding or for degradation, mostly by the proteasome...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28559586/a%C3%AE-42-pentamers-hexamers-are-the-smallest-detectable-oligomers-in-solution
#19
Martin Wolff, Bo Zhang-Haagen, Christina Decker, Bogdan Barz, Mario Schneider, Ralf Biehl, Aurel Radulescu, Birgit Strodel, Dieter Willbold, Luitgard Nagel-Steger
Amyloid β (Aβ) oligomers may play a decisive role in Alzheimer's disease related neurodegeneration, but their structural properties are poorly understood. In this report, sedimentation velocity centrifugation, small angle neutron scattering (SANS) and molecular modelling were used to identify the small oligomeric species formed by the 42 amino acid residue long isoform of Aβ (Aβ42) in solution, characterized by a sedimentation coefficient of 2.56 S, and a radius of gyration between 2 and 4 nm. The measured sedimentation coefficient is in close agreement with the sedimentation coefficient calculated for Aβ42 hexamers using MD simulations at µM concentration...
May 30, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28557010/rapid-amyloid-%C3%AE-oligomer-and-protofibril-accumulation-in-traumatic-brain-injury
#20
Sami Abu Hamdeh, Erik Rollman Waara, Christer Möller, Linda Söderberg, Hans Basun, Irina Alafuzoff, Lars Hillered, Lars Lannfelt, Martin Ingelsson, Niklas Marklund
OBJECTIVE: Deposition of amyloid-β (Aβ) is central to Alzheimer's disease (AD) pathogenesis and associated with progressive neurodegeneration in traumatic brain injury (TBI). We analysed predisposing factors for Aβ deposition including monomeric Aβ40, Aβ42 and Aβ oligomers/protofibrils, Aβ species with pronounced neurotoxic properties, following human TBI. METHODS: Highly selective ELISAs were used to analyse N-terminally intact and truncated Aβ40 and Aβ42, as well as Aβ oligomers/protofibrils, in human brain tissue, surgically resected from severe TBI patients (n=12; mean age 49...
May 29, 2017: Brain Pathology
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