Read by QxMD icon Read

Amyloid oligomers

Tong Lu, Feihong Meng, Ying Wei, Yang Li, Chunyu Wang, Fei Li
The formation of prefibrillar intermediates is a key stage not only for the fibrillation of amyloid peptides but also for their cytotoxicity. The heterogeneous and transient nature of most prefibrillar intermediates make them difficult to be separated, identified, and characterized. Rat islet amyloid polypeptide (rIAPP) has a weak propensity of fibrillation under most solution conditions and is found to be cytotoxic, which enables us to characterize prefibrillar species formed at various oligomeric states and explore the mechanism of membrane damage by these oligomers...
March 20, 2018: Physical Chemistry Chemical Physics: PCCP
Myeongsang Lee, Jae In Kim, Sungsoo Na, Kilho Eom
Amyloid β (Aβ) aggregates, which are a hallmark for neurodegenerative disease, are formed through a self-assembly process such as aggregation of Aβ peptide chains. This aggregation process depends on the solvent conditions under which the proteins are aggregated. Nevertheless, the underlying mechanism of the ionic effect on the formation and stability of amyloid aggregates has not been fully understood. Here, we report how metal ions play a role in the formation and stability of Aβ aggregates at different length scales, i...
March 20, 2018: Physical Chemistry Chemical Physics: PCCP
Ming-Che Lee, Wan-Cheng Yu, Yao-Hsiang Shih, Chun-Yu Chen, Zhong-Hong Guo, Shing-Jong Huang, Jerry C C Chan, Yun-Ru Chen
Alzheimer's disease (AD) is the most prevalent neurodegenerative disease in the elderly. Zinc (Zn) ion interacts with the pathogenic hallmark, amyloid-β (Aβ), and is enriched in senile plaques in brain of AD patients. To understand Zn-chelated Aβ (ZnAβ) species, here we systematically characterized ZnAβ aggregates by incubating equimolar Aβ with Zn. We found ZnAβ40 and ZnAβ42 both form spherical oligomers with a diameter of ~12-14 nm composed of reduced β-sheet content. Oligomer assembly examined by analytical ultracentrifugation, hydrophobic exposure by BisANS spectra, and immunoreactivity of ZnAβ and Aβ derived diffusible ligands (ADDLs) are distinct...
March 19, 2018: Scientific Reports
Xinwei Ge, Yunxiang Sun, Feng Ding
Accumulating evidence suggests that soluble oligomers are more toxic than final fibrils of amyloid aggregations. Among the mixture of inter-converting intermediates with continuous distribution of sizes and secondary structures, oligomers in the β-barrel conformation - a common class of protein folds with a closed β-sheet - have been postulated as the toxic species with well-defined three-dimensional structures to perform pathological functions. A common mechanism for amyloid toxicity, therefore, implies that all amyloid peptides should be able to form β-barrel oligomers as the aggregation intermediates...
March 14, 2018: Biochimica et Biophysica Acta
Mitchell R White, Ruth Kandel, I-Ni Hsieh, Xavier De Luna, Kevan L Hartshorn
Recent studies have shown that the Alzheimer's associated β-amyloid protein (βA) can inhibit growth of bacteria, fungi and viruses. We reported that the 42 amino acid βA protein inhibits replication of seasonal and pandemic strains of H3N2 and H1N1 influenza A virus (IAV) in vitro and modulates activation of neutrophils and monocytes exposed IAV. We here show that fragments composed of the N and C terminal domain of βA42, including βA22-42 and the 8 amino acid βA35-42, retain viral neutralizing and viral aggregating activity, whereas fragments lacking the C-terminal amino acids 41 and 42 (e...
2018: PloS One
Xueying Wang, Ksenia V Kastanenka, Michal Arbel-Ornath, Caitlin Commins, Akira Kuzuya, Amanda J Lariviere, Grant A Krafft, Franz Hefti, Jasna Jerecic, Brian J Bacskai
Soluble amyloid β oligomers (AβOs) are widely recognized neurotoxins that trigger aberrant signaling in specific subsets of neurons, leading to accumulated neuronal damage and memory disorders in Alzheimer's disease (AD). One of the profound downstream consequences of AβO-triggered events is dysregulation of cytosolic calcium concentration ([Ca2+ ]i ), which has been implicated in synaptic failure, cytoskeletal abnormalities, and eventually neuronal death. We have developed an in vitro/in vivo drug screening assay to evaluate putative AβO-blocking candidates by measuring AβO-induced real-time changes in [Ca2+ ]i ...
March 15, 2018: Scientific Reports
O V Galzitskaya, E I Galushko, O M Selivanova
Studies of the process of amyloid formation by Aβ peptide have been topical due to the critical role of this peptide in the pathogenesis of Alzheimer's disease. Many articles devoted to this process are available in the literature; however, none of them gives a detailed description of the mechanism of the process of generation of amyloids. Moreover, there are no reliable data on the influence of modified forms of Aβ peptide on its amyloid formation. To appreciate the role of Aβ aggregation in the pathogenesis of Alzheimer's disease and to develop a strategy for its treatment, it is necessary to have a well-defined description of the molecular mechanism underlying the formation of amyloids as well as the contribution of each intermediate to this process...
January 2018: Biochemistry. Biokhimii︠a︡
Yuanyuan Wang, Qinwen Wang, Xiaoming Bao, Yanfei Ding, Jieyi Shentu, Wei Cui, Xiaowei Chen, Xiaofei Wei, Shujun Xu
Taxifolin is a potent flavonoid with anti-inflammatory activity. Taxifolin has been reported to decrease the accumulation of β-amyloid (Aβ), and reduce Aβ-induced neurotoxicity. However, the detail molecular mechanism of taxifolin against Aβ-induced neurotoxicity is largely unknown. In this study, we revealed the protective effects and the underlying mechanisms of taxifolin on the impairments of cognitive function and synapse formation induced by soluble Aβ oligomers. Our results showed that taxifolin prevented neuronal cell death in a concentration-dependent manner...
March 14, 2018: Metabolic Brain Disease
Italo A Cavini, Claudia E Munte, Markus Beck Erlach, Thomas van Groen, Inga Kadish, Tao Zhang, Tamar Ziehm, Luitgard Nagel-Steger, Janine Kutzsche, Werner Kremer, Dieter Willbold, Hans Robert Kalbitzer
Pressure can shift the polymer-monomer equilibrium of Aβ, increasing pressure first leads to a release of Aβ-monomers, surprisingly at pressures higher than 180 MPa repolymerization is induced. By high pressure NMR spectroscopy, differences of partial molar volumes ΔV0 and compressibility factors Δβ' of polymerization were determined at different temperatures. The d-enantiomeric peptides RD2 and RD2D3 bind to monomeric Aβ with affinities substantially higher than those determined for fibril formation...
March 14, 2018: Chemical Communications: Chem Comm
Xiaocui Fang, Maryam Yousaf, Qunxing Huang, Yanlian Yang, Chen Wang
The oligomerization and fibrillation of human islet amyloid polypeptide (hIAPP) play a central role in the pathogenesis of type 2 diabetes. Strategies for remodelling the formation of hIAPP oligomers and fibrils have promising application potential in type 2 diabetes therapy. Herein, we demonstrated that PEG-PE micelle could inhibit hIAPP oligomerization and fibrillation through blocking the hydrophobic interaction and the conformational change from random coil to β-sheet structures of hIAPP. In addition, we also found that PEG-PE micelle could remodel the preformed hIAPP fibrils allowing the formation of short fibrils and co-aggregates...
March 13, 2018: Scientific Reports
José A Del Río, Isidre Ferrer, Rosalina Gavín
Several studies have indicated that certain misfolded amyloids composed of tau, β-amyloid or α-synuclein can be transferred from cell to cell, suggesting the contribution of mechanisms reminiscent of those by which infective prions spread through the brain. This process of a 'prion-like' spreading between cells is also relevant as a novel putative therapeutic target that could block the spreading of proteinaceous aggregates throughout the brain which may underlie the progressive nature of neurodegenerative diseases...
March 9, 2018: Progress in Neurobiology
Xuewei Dong, Qin Qiao, Zhenyu Qian, Guanghong Wei
The amyloid deposits of human islet amyloid polypeptide (hIAPP) are found in type II diabetes patients. hIAPP monomer is intrinsically disordered in solution, whereas it can form amyloid fibrils both in vivo and in vitro. Extensive evidence suggests that hIAPP causes the disruption of cellular membrane, and further induces cytotoxicity and the death of islet β-cells in pancreas. The presence of membrane also accelerates the hIAPP fibril formation. hIAPP oligomers and protofibrils in the early stage of aggregation were reported to be the most cytotoxic, disrupting the membrane integrity and giving rise to the pathological process...
March 9, 2018: Biochimica et Biophysica Acta
Vijayaraghavan Rangachari, Dexter N Dean, Pratip Rana, Ashwin Vaidya, Preetam Ghosh
Self-templating propagation of protein aggregate conformations is increasingly becoming a significant factor in many neurological diseases. In Alzheimer disease (AD), intrinsically disordered amyloid-β (Aβ) peptides undergo aggregation that is sensitive to environmental conditions. High-molecular weight aggregates of Aβ that form insoluble fibrils are deposited as senile plaques in AD brains. However, low-molecular weight aggregates called soluble oligomers are known to be the primary toxic agents responsible for neuronal dysfunction...
March 8, 2018: Biochimica et Biophysica Acta
Can Kayatekin, Audra Amasino, Giorgio Gaglia, Jason Flannick, Julia M Bonner, Saranna Fanning, Priyanka Narayan, M Inmaculada Barrasa, David Pincus, Dirk Landgraf, Justin Nelson, William R Hesse, Michael Costanzo, Chad L Myers, Charles Boone, Jose C Florez, Susan Lindquist
Aggregates of human islet amyloid polypeptide (IAPP) in the pancreas of patients with type 2 diabetes (T2D) are thought to contribute to β cell dysfunction and death. To understand how IAPP harms cells and how this might be overcome, we created a yeast model of IAPP toxicity. Ste24, an evolutionarily conserved protease that was recently reported to degrade peptides stuck within the translocon between the cytoplasm and the endoplasmic reticulum, was the strongest suppressor of IAPP toxicity. By testing variants of the human homolog, ZMPSTE24, with varying activity levels, the rescue of IAPP toxicity proved to be directly proportional to the declogging efficiency...
March 5, 2018: Cell
Csaba Fekete, Csaba Vastagh, Ádám Dénes, Erik Hrabovszky, Gábor Nyiri, Imre Kalló, Zsolt Liposits, Miklós Sárvári
Microglia are instrumental for recognition and elimination of amyloid β1-42 oligomers (AβO), but the long-term consequences of AβO-induced inflammatory changes in the brain are unclear. Here, we explored microglial responses and transciptome-level inflammatory signatures in the rat hippocampus after chronic AβO challenge. Middle-aged Long Evans rats received intracerebroventricular infusion of AβO or vehicle for 4 weeks, followed by treatment with artificial CSF or MCC950 for the subsequent 4 weeks. AβO infusion evoked a sustained inflammatory response including activation of NF-κB, triggered microglia activation and increased the expression of pattern recognition and phagocytic receptors...
March 6, 2018: Neuroscience
Blagojce Jovcevski, J Andrew Aquilina, Justin L P Benesch, Heath Ecroyd
αB-Crystallin (HSPB5) is a small heat-shock protein that is composed of dimers that then assemble into a polydisperse ensemble of oligomers. Oligomerisation is mediated by heterologous interactions between the C-terminal tail of one dimer and the core "α-crystallin" domain of another and stabilised by interactions made by the N-terminal region. Comparatively little is known about the latter contribution, but previous studies have suggested that residues in the region 54-60 form contacts that stabilise the assembly...
March 8, 2018: Cell Stress & Chaperones
Simona Daniele, Daniela Frosini, Deborah Pietrobono, Lucia Petrozzi, Annalisa Lo Gerfo, Filippo Baldacci, Jonathan Fusi, Chiara Giacomelli, Gabriele Siciliano, Maria Letizia Trincavelli, Ferdinando Franzoni, Roberto Ceravolo, Claudia Martini, Ubaldo Bonuccelli
Neurodegenerative disorders (NDs) are characterized by abnormal accumulation/misfolding of specific proteins, primarily α-synuclein (α-syn), β-amyloid1-42 (Aβ1-42 ) and tau, in both brain and peripheral tissues. In addition to oligomers, the role of the interactions of α-syn with Aβ or tau has gradually emerged. Nevertheless, despite intensive research, NDs have no accepted peripheral markers for biochemical diagnosis. In this respect, Red Blood Cells (RBCs) are emerging as a valid peripheral model for the study of aging-related pathologies...
2018: Frontiers in Molecular Neuroscience
Yingjun Zhao, Xilin Wu, Xiaoguang Li, Lu-Lin Jiang, Xun Gui, Yan Liu, Yu Sun, Bing Zhu, Juan C Piña-Crespo, Muxian Zhang, Ningyan Zhang, Xiaochun Chen, Guojun Bu, Zhiqiang An, Timothy Y Huang, Huaxi Xu
Mutations in triggering receptor expressed on myeloid cells 2 (TREM2) have been linked to increased Alzheimer's disease (AD) risk. Neurobiological functions of TREM2 and its pathophysiological ligands remain elusive. Here we found that TREM2 directly binds to β-amyloid (Aβ) oligomers with nanomolar affinity, whereas AD-associated TREM2 mutations reduce Aβ binding. TREM2 deficiency impairs Aβ degradation in primary microglial culture and mouse brain. Aβ-induced microglial depolarization, K+ inward current induction, cytokine expression and secretion, migration, proliferation, apoptosis, and morphological changes are dependent on TREM2...
March 7, 2018: Neuron
A V Finkelstein, N V Dovidchenko, O V Galzitskaya
Meisl et al. have recently observed an anomalous dependence of the amyloid formation rate on the protein concentration. A novel mechanism of fibril growth has been proposed by Meisl et al. to explain the abnormality; it consists in the fibril-catalyzed initiation of fibril formation with saturation of catalytic sites at high concentrations of substrates. Our article describes an alternative explanation of the anomalous kinetics, assuming that the formation of metastable oligomers competes with fibril formation by decreasing the concentration of free monomers...
January 2018: Molekuliarnaia Biologiia
Kayla M Pate, Brandon J Kim, Eric V Shusta, Regina M Murphy
β-amyloid (Aβ) aggregation is causally linked to neuronal pathology in Alzheimer's disease; therefore, several small molecules, antibodies, and peptides have been tested as anti-Aβ agents. We developed two compounds based on the Aβ-binding domain of transthyretin (TTR), a cyclic peptide cG8 and an engineered protein mTTR, and compared them for therapeutically relevant properties. Both mTTR and cG8 inhibit fibrillogenesis of Aβ, with mTTR inhibiting at a lower concentration than cG8. Both inhibit aggregation of amylin but not of α-synuclein...
March 7, 2018: ChemMedChem
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"