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amyloid oligomer

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https://www.readbyqxmd.com/read/28650319/somatostatin-binds-to-the-human-amyloid-%C3%AE-peptide-and-favors-the-formation-of-distinct-oligomers
#1
Hansen Wang, Lisa D Muiznieks, Punam Ghosh, Declan Williams, Michael Solarski, Andrew Fang, Alejandro Ruiz-Riquelme, Régis Pomès, Joel C Watts, Avi Chakrabartty, Holger Wille, Simon Sharpe, Gerold Schmitt-Ulms
The amyloid β peptide (Aβ) is a key player in the etiology of Alzheimer disease (AD), yet a systematic investigation of its molecular interactions has not been reported. Here we identified by quantitative mass spectrometry proteins in human brain extract that bind to oligomeric Aβ1-42 (oAβ1-42) and/or monomeric Aβ1-42 (mAβ1-42) baits. Remarkably, the cyclic neuroendocrine peptide somatostatin-14 (SST14) was observed to be the most selectively enriched oAβ1-42 binder. The binding interface comprises a central tryptophan within SST14 and the N-terminus of Aβ1-42...
June 26, 2017: ELife
https://www.readbyqxmd.com/read/28649012/small-molecule-probes-of-protein-aggregation
#2
REVIEW
Lydia M Young, Alison E Ashcroft, Sheena E Radford
Understanding the mechanisms of amyloid formation and toxicity remain major challenges. Although substantial progress has been made in the development of methods able to identify the species formed during self-assembly and to describe the kinetic mechanisms of aggregation, the structure(s) of non-native species, including potentially toxic oligomers, remain elusive. Moreover, how fibrils contribute to disease remains unclear. Here we review recent advances in the development of small molecules and other reagents that are helping to define the mechanisms of protein aggregation in molecular detail...
June 22, 2017: Current Opinion in Chemical Biology
https://www.readbyqxmd.com/read/28648936/diagnostic-pathology-of-alzheimer-s-disease-from-routine-microscopy-to-immunohistochemistry-and-experimental-correlations
#3
Gerard Nuovo, Bernard Paniccia, Louisa Mezache, Maria Quiñónez, James Williams, Paige Vandiver, Paolo Fadda, Vicky Amann
The absence of any histologic correlate for Alzheimer's disease despite its commonness and severe clinical sequelae may offers clues to its etiology. Recent evidence strongly suggests that the central event of this disease is the hyperphosphorylation of neuronal tau protein and not the beta amyloid precipitates. In each case, essential and soluble neuronal proteins derivatives form insoluble aggregates that can readily be detected by immunohistochemistry using antibodies specific for the misfolded proteins...
June 2017: Annals of Diagnostic Pathology
https://www.readbyqxmd.com/read/28647556/synapsin-i-phosphorylation-is-dysregulated-by-beta-amyloid-oligomers-and-restored-by-valproic-acid
#4
Jade Marsh, Saifuddien Haji Bagol, Robin S B Williams, George Dickson, Pavlos Alifragis
Alzheimer's disease is the most prevalent form of dementia in the elderly but the precise causal mechanisms are still not fully understood. Growing evidence supports a significant role for Aβ42 oligomers in the development and progression of Alzheimer's. For example, intracellular soluble Aβ oligomers are thought to contribute to the early synaptic dysfunction associated with Alzheimer's disease, but the molecular mechanisms underlying this effect are still unclear. Here, we identify a novel mechanism that contributes to our understanding of the reported synaptic dysfunction...
June 21, 2017: Neurobiology of Disease
https://www.readbyqxmd.com/read/28644501/stabilizing-amyloid-%C3%AE-peptide-by-the-n-terminus-capture-is-capable-of-preventing-and-eliminating-amyloid-%C3%AE-oligomers
#5
Gesi Wen, Daoyuan Chen, Wenjing Qin, Binhua Zhou, Youqiao Wang, Ziyi Liu, Jun Du, Qiang Zhou, Junmin Quan, Xianzhang Bu
Elimination of amyloid-β (Aβ) oligomers remains challenging. We describe here a novel strategy to prevent and eliminate the Aβ oligomers from either the early aggregation or the fibril dissolution pathway by targeting the flexible N-terminus, but not the widely investigated hydrophobic segment, with a rationally designed cyclopeptide.
June 23, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28642346/detergent-induced-self-assembly-and-controllable-photosensitizer-activity-of-diester-phenylene-ethynylenes
#6
Patrick L Donabedian, Matthew N Creyer, Florencia A Monge, Kirk S Schanze, Eva Y Chi, David G Whitten
Photodynamic therapy, in which malignant tissue is killed by targeted light exposure following administration of a photosensitizer, can be a valuable treatment modality but currently relies on passive transport and local irradiation to avoid off-target oxidation. We present a system of excited-state control for truly local delivery of singlet oxygen. An anionic phenylene ethynylene oligomer is initially quenched by water, producing minimal fluorescence and no measurable singlet oxygen generation. When presented with a binding partner, in this case an oppositely charged surfactant, changes in solvent microenvironment result in fluorescence unquenching, restoration of intersystem crossing to the triplet state, and singlet oxygen generation, as assayed by transient absorption spectroscopy and chemical trapping...
June 22, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28641562/structural-characterization-of-amyloid-%C3%AE-17-42-dimer-by-potential-of-mean-force-analysis-insights-from-molecular-dynamics-simulations
#7
Mary Dutta, Rajkalyan Chutia, Venkata Satish Kumar Mattaparthi
Recent experiments with Amyloid β1-42 peptide have indicated that the initial dimerization of Aβ1-42 monomers to form amyloid dimers stand out as a key event in the generation of toxic oligomers. However, the structural characterization of Aβ1-42 dimer at the atomistic level and the dimerization mechanism by which Aβ1-42 peptides co-aggregate still remains not clear. In the present study, the process of Aβ17-42 peptide dimerization which is known to play an important role in the plaque formation was evaluated in terms of potential of mean force, which provided free energies along the reaction coordinates...
June 20, 2017: Protein and Peptide Letters
https://www.readbyqxmd.com/read/28624352/pressure-effects-on-%C3%AE-synuclein-amyloid-fibrils-an-experimental-investigation-on-their-dissociation-and-reversible-nature
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
#14
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 12, 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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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