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Tau oligomers

Moran Frenkel-Pinter, Sharon Tal, Roni Scherzer-Attali, Malak Abu-Hussien, Idan Alyagor, Tal Eisenbaum, Ehud Gazit, Daniel Segal
Alzheimer's disease (AD) is the most abundant tauopathy and is characterized by Aβ-derived plaques and tau-derived tangles, resulting from the unfolding of the corresponding monomeric subunits into ordered β-sheet oligomers and fibrils. Intervening in the toxic aggregation process is a promising therapeutic approach, but, to date, a disease-modifying therapy is neither available for AD nor for other tauopathies. Along these lines, we have previously demonstrated that a small naphthoquinone-tryptophan hybrid, termed NQTrp, is an effective modulator of tauopathy in vitro and in vivo...
October 20, 2016: Neuro-degenerative Diseases
Susanne Wegmann, Samantha Nicholls, Shuko Takeda, Zhanyun Fan, Bradley T Hyman
Tau is a neuronal microtubule binding protein that, in Alzheimer's disease and other neurodegenerative diseases, can form oligomeric and large fibrillar aggregates, which deposit in neurofibrillary tangles. Tau's physiological state of multimerization appears to vary across conditions, and a stable dimeric form of soluble tau has been suggested from experiments using recombinant tau in vitro. We tested if tau dimerization, or oligomerization, also occurs in cells, and if soluble tau oligomers are relevant for the release and internalization of tau...
October 12, 2016: Journal of Neurochemistry
Darrell Sawmiller, Ahsan Habib, Song Li, Donna Darlington, Huayan Hou, Jun Tian, R Douglas Shytle, Adam Smith, Brian Giunta, Takashi Mori, Jun Tan
Naturally-occurring bioactive flavonoids such as diosmin significantly reduces amyloid beta (Aβ) associated pathology in Alzheimer's disease (AD) mouse models. In the present study, oral administration of diosmin reduced cerebral Aβ oligomer levels, tau-hyperphosphorylation and cognitive impairment in the 3xTg-AD mouse model through glycogen synthase kinase-3 (GSK-3) and transient receptor potential canonical 6-related mechanisms. Diosmetin, one major bioactive metabolite of diosmin, increased inhibitory GSK-3β phosphorylation, while selectively reducing γ-secretase activity, Aβ generation, tau hyperphosphorylation and pro-inflammatory activation of microglia in vitro, without altering Notch processing...
October 15, 2016: Journal of Neuroimmunology
Ashley N Nilson, Kelsey C English, Julia E Gerson, T Barton Whittle, C Nicolas Crain, Judy Xue, Urmi Sengupta, Diana L Castillo-Carranza, Wenbo Zhang, Praveena Gupta, Rakez Kayed
It is well-established that inflammation plays an important role in Alzheimer's disease (AD) and frontotemporal lobar dementia (FTLD). Inflammation and synapse loss occur in disease prior to the formation of larger aggregates, but the contribution of tau to inflammation has not yet been thoroughly investigated. Tau pathologically aggregates to form large fibrillar structures known as tangles. However, evidence suggests that smaller soluble aggregates, called oligomers, are the most toxic species and form prior to tangles...
October 1, 2016: Journal of Alzheimer's Disease: JAD
Andrés Norambuena, Horst Wallrabe, Lloyd McMahon, Antonia Silva, Eric Swanson, Shahzad S Khan, Daniel Baerthlein, Erin Kodis, Salvatore Oddo, James W Mandell, George S Bloom
A major obstacle to presymptomatic diagnosis and disease-modifying therapy for Alzheimer's disease (AD) is inadequate understanding of molecular mechanisms of AD pathogenesis. For example, impaired brain insulin signaling is an AD hallmark, but whether and how it might contribute to the synaptic dysfunction and neuron death that underlie memory and cognitive impairment has been mysterious. Neuron death in AD is often caused by cell cycle reentry (CCR) mediated by amyloid-β oligomers (AβOs) and tau, the precursors of plaques and tangles...
September 29, 2016: Alzheimer's & Dementia: the Journal of the Alzheimer's Association
Julia E Gerson, Amrit Mudher, Rakez Kayed
The culmination of many years of increasing research into the toxicity of tau aggregation in neurodegenerative disease has led to the consensus that soluble, oligomeric forms of tau are likely the most toxic entities in disease. While tauopathies overlap in the presence of tau pathology, each disease has a unique combination of symptoms and pathological features; however, most study into tau has grouped tau oligomers and studied them as a homogenous population. Established evidence from the prion field combined with the most recent tau and amyloidogenic protein research suggests that tau is a prion-like protein, capable of seeding the spread of pathology throughout the brain...
September 21, 2016: Critical Reviews in Biochemistry and Molecular Biology
Abolfazl Jangholi, Mohammad Reza Ashrafi-Kooshk, Seyed Shahriar Arab, Gholamhossein Riazi, Farzad Mokhtari, Mansour Poorebrahim, Hamid Mahdiuni, Boris I Kurganov, Ali Akbar Moosavi-Movahedi, Reza Khodarahmi
In many neurodegenerative diseases, formation of protein fibrillar aggregates has been observed as a major pathological change. Neurofibrillary tangles, mainly composed of fibrils formed by the microtubule-associated protein; Tau, are a hallmark of a group of neurodegenerative diseases such as Alzheimer's disease. Tau belongs to the class of natively unfolded proteins and partially folds into an ordered β-structure during aggregation. Polyanionic cofactors such as heparin are commonly used as inducer of Tau aggregation in vitro...
November 1, 2016: Archives of Biochemistry and Biophysics
Mathew A Sherman, Michael LaCroix, Fatou Amar, Megan E Larson, Colleen Forster, Adriano Aguzzi, David A Bennett, Martin Ramsden, Sylvain E Lesné
UNLABELLED: Despite the demonstration that amyloid-β (Aβ) can trigger increased tau phosphorylation and neurofibrillary tangle (NFT) formation in vivo, the molecular link associating Aβ and tau pathologies remains ill defined. Here, we observed that exposure of cultured primary neurons to Aβ trimers isolated from brain tissue of subjects with Alzheimer's disease led to a specific conformational change of tau detected by the antibody Alz50. A similar association was supported by postmortem human brain analyses...
September 14, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Jun Yoshitake, Yoshiyuki Soeda, Tomoaki Ida, Akio Sumioka, Misato Yoshikawa, Kenji Matsushita, Takaaki Akaike, Akihiko Takashima
Neurofibrillarly tangles caused by intracellular hyperphosphorylated tau inclusion and extracellular amyloid β peptide deposition are hallmarks of Alzheimer's disease. Tau contains one or two cysteine residues in three-repeat or four-repeat of microtubule binding region following alternative splicing of exon 10, and formation of intermolecular cysteine disulfide bonds accelerate tau aggregation. 8-nitroguanosine 3',5'-cyclicmonophosphate (8-nitro-cGMP) acts as a novel second messenger of nitric oxide (NO) by covalently binding cGMP to cysteine residues by electrophilic properties, a process termed protein S-guanylation...
September 6, 2016: Journal of Biological Chemistry
Siân Baker, Juan Carlos Polanco, Jϋrgen Götz
In Alzheimer's disease, the distribution of neurofibrillary tangles, a histological hallmark comprised of phosphorylated forms of the protein tau, follows a distinct pattern through anatomically connected brain regions. The well-documented correlation between the severity of tau pathology and disease progression implies a prion-like seeding and spreading mechanism for tau. Experimentally, this has been addressed in transgenic mice by the injection of protein lysates isolated from brains of transgenic mice or patients with tauopathies, including AD, that were shown to behave like seeds, accelerating tau pathology and tangle formation in predisposed mice...
October 4, 2016: Journal of Alzheimer's Disease: JAD
Qingwei Ruan, Grazia D'Onofrio, Daniele Sancarlo, Antonio Greco, Zhuowei Yu
Cognitive frailty (CF) overlaps with early neuropathological alterations associated with aging‑related major neurocognitive disorders, including Alzheimer's disease (AD). Fluid biomarkers for these pathological brain alterations allow for early diagnosis in the preclinical stages of AD, and for objective prognostic assessments in clinical intervention trials. These biomarkers may also be helpful in the screening of CF. The present study reviewed the literature and identified systematic reviews of cohort studies and other authoritative reports...
October 2016: Molecular Medicine Reports
Brian Spencer, Paula A Desplats, Cassia R Overk, Elvira Valera-Martin, Robert A Rissman, Chengbiao Wu, Michael Mante, Anthony Adame, Jazmin Florio, Edward Rockenstein, Eliezer Masliah
UNLABELLED: Alzheimer's disease (AD) is characterized by the progressive accumulation of amyloid β (Aβ) and microtubule associate protein tau, leading to the selective degeneration of neurons in the neocortex, limbic system, and nucleus basalis, among others. Recent studies have shown that α-synuclein (α-syn) also accumulates in the brains of patients with AD and interacts with Aβ and tau, forming toxic hetero-oligomers. Although the involvement of α-syn has been investigated extensively in Lewy body disease, less is known about the role of this synaptic protein in AD...
July 27, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Farzad Mokhtari, Gholamhossein Riazi, Saeed Balalaie, Reza Khodarahmi, Saeed Karima, Azam Hemati, Bahram Bolouri, Fatemeh Hedayati Katouli, Esmat Fathi
No abstract text is available yet for this article.
October 2016: Neuropeptides
Miquel Martorell, Katherine Forman, Natalia Castro, Xavier Capó, Silvia Tejada, Antoni Sureda
Alzheimer's disease (AD) is an age-associated neurodegenerative amyloid disease and is considered a social and clinical problem the last decades, particularly in the Western countries. Amyloid diseases are characterized by the deposition of typically aggregated protein/peptides in tissues that are associated with brain degeneration and progressive cognitive impairment. The amyloid plaques and neurofibrillary tangles arise as a result of self-assembly into fibrillar material of amyloid-β protein and hyperphosphorylated tau, respectively...
2016: Current Pharmaceutical Biotechnology
Molly Stanley, Shannon L Macauley, David M Holtzman
Individuals with type 2 diabetes have an increased risk for developing Alzheimer's disease (AD), although the causal relationship remains poorly understood. Alterations in insulin signaling (IS) are reported in the AD brain. Moreover, oligomers/fibrils of amyloid-β (Aβ) can lead to neuronal insulin resistance and intranasal insulin is being explored as a potential therapy for AD. Conversely, elevated insulin levels (ins) are found in AD patients and high insulin has been reported to increase Aβ levels and tau phosphorylation, which could exacerbate AD pathology...
July 25, 2016: Journal of Experimental Medicine
Francesca Pistollato, Sandra Sumalla Cano, Iñaki Elio, Manuel Masias Vergara, Francesca Giampieri, Maurizio Battino
Accumulation of proteinaceous amyloid β plaques and tau oligomers may occur several years before the onset of Alzheimer disease (AD). Under normal circumstances, misfolded proteins get cleared by proteasome degradation, autophagy, and the recently discovered brain glymphatic system, an astroglial-mediated interstitial fluid bulk flow. It has been shown that the activity of the glymphatic system is higher during sleep and disengaged or low during wakefulness. As a consequence, poor sleep quality, which is associated with dementia, might negatively affect glymphatic system activity, thus contributing to amyloid accumulation...
July 2016: Advances in Nutrition
Giusi Manassero, Michela Guglielmotto, Raluca Zamfir, Roberta Borghi, Laura Colombo, Mario Salmona, George Perry, Patrizio Odetti, Ottavio Arancio, Elena Tamagno, Massimo Tabaton
The mechanistic relationship between amyloid β1-42 (Aβ1-42) and the alteration of Tau protein are debated. We investigated the effect of Aβ1-42 monomers and oligomers on Tau, using mice expressing wild-type human Tau that do not spontaneously develop Tau pathology. After intraventricular injection of Aβ1-42, mice were sacrificed after 3 h or 4 days. The short-lasting treatment with Aβ monomers, but not oligomers, showed a conformational PHF-like change of Tau, together with hyperphosphorylation. The same treatment induced increase in concentration of GSK3 and MAP kinases...
October 2016: Aging Cell
Aleš Benda, Hayden Aitken, Danielle S Davies, Renee Whan, Claire Goldsbury
Alzheimer's disease (AD) involves the propagation of filaments of tau protein throughout the cerebral cortex. Imaging tau filaments and oligomers in human brain at high resolution would help contribute insight into the mechanism and progression of tauopathic diseases. STED microscopy is a nano-scale imaging technique and we aimed to test the abilities of this method for resolving tau structures within human brain. Using autopsied 50μm AD brain sections, we demonstrate that STED microscopy can resolve immunolabelled tau filaments at 77nm resolution...
September 2016: Journal of Structural Biology
Armand Savioz, Panteleimon Giannakopoulos, François R Herrmann, William L Klein, Enikö Kövari, Constantin Bouras, Ezio Giacobini
BACKGROUND/AIMS: Investigations of Aβ oligomers in neuropathologically confirmed Alzheimer's disease (AD) are still scarce. We report neurohistopathological and biochemical analyses using antibodies against tau and amyloid β (Aβ) pathology. METHODS: Thirty elderly AD patients and 43 age-matched controls with or without deposition of amyloid plaques (AP) were analyzed by immunohistochemistry. In 21 cases with available fresh tissue, Western blots were also performed...
2016: Neuro-degenerative Diseases
Chelsea T Tiernan, Benjamin Combs, Kristine Cox, Gerardo Morfini, Scott T Brady, Scott E Counts, Nicholas M Kanaan
In Alzheimer's disease (AD), tau undergoes numerous modifications, including increased phosphorylation at serine-422 (pS422). In the human brain, pS422 tau protein is found in prodromal AD, correlates well with cognitive decline and neuropil thread pathology, and appears associated with increased oligomer formation and exposure of the N-terminal phosphatase-activating domain (PAD). However, whether S422 phosphorylation contributes to toxic mechanisms associated with disease-related forms of tau remains unknown...
September 2016: Experimental Neurology
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