Dephosphorylation Passivates the Seeding Activity of Oligomeric Tau Derived From Alzheimer’s Brain

Accumulation of intracellular neurofibrillary tangles (NFTs), which are constituted of abnormally phosphorylated tau, is one of the neuropathological hallmarks of Alzheimer’s disease (AD). The oligomeric aggregates of tau in AD brain (AD O-tau) are believed to trigger NFT spreading by seeding normal tau aggregation as toxic seeds, in a prion-like fashion. Here, we revealed the features of AD O-tau by Western blots using antibodies against various epitopes and determined the effect of dephosphorylation on the seeding activity of AD O-tau by capture and seeded aggregation assays. We found that N-terminal truncated and C-terminalhyperphosphorylated tau species were enriched in AD O-tau. Dephosphorylation of AD O-tau by alkaline phosphatasediminished its activity in capturing tau in vitro and ininducing insoluble aggregates in cultured cells. Our resultssuggested that dephosphorylation passivated the seeding activity ofAD O-tau. Inhibition of phosphorylation may be a potentstrategy to prevent the spreading of tau patho3logy.

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Arrayed CRISPR reveals genetic regulators of tau aggregation, autophagy and mitochondria in Alzheimer’s disease model

Scientific Reports ◽

10.1038/s41598-021-82658-7 ◽

2021 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Lishu Duan ◽

Mufeng Hu ◽

Joseph A. Tamm ◽

Yelena Y. Grinberg ◽

Fang Shen ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Drug Discovery ◽

Disease Model ◽

Mitochondrial Morphology ◽

Individual Gene ◽

Human Genes ◽

Future Drug ◽

Tau Aggregation

AbstractAlzheimer’s disease (AD) is a common neurodegenerative disease with poor prognosis. New options for drug discovery targets are needed. We developed an imaging based arrayed CRISPR method to interrogate the human genome for modulation of in vitro correlates of AD features, and used this to assess 1525 human genes related to tau aggregation, autophagy and mitochondria. This work revealed (I) a network of tau aggregation modulators including the NF-κB pathway and inflammatory signaling, (II) a correlation between mitochondrial morphology, respiratory function and transcriptomics, (III) machine learning predicted novel roles of genes and pathways in autophagic processes and (IV) individual gene function inferences and interactions among biological processes via multi-feature clustering. These studies provide a platform to interrogate underexplored aspects of AD biology and offer several specific hypotheses for future drug discovery efforts.

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“Don’t Phos Over Tau”: recent developments in clinical biomarkers and therapies targeting tau phosphorylation in Alzheimer’s disease and other tauopathies

Molecular Neurodegeneration ◽

10.1186/s13024-021-00460-5 ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

Yuxing Xia ◽

Stefan Prokop ◽

Benoit I. Giasson

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Cerebrospinal Fluid ◽

Kinase Inhibitors ◽

Tau Phosphorylation ◽

Phosphorylated Tau ◽

Clinical Biomarkers ◽

Early Results ◽

Recent Developments ◽

Tau Aggregation

AbstractPhosphorylation is one of the most prevalent post-translational modifications found in aggregated tau isolated from Alzheimer’s disease (AD) patient brains. In tauopathies like AD, increased phosphorylation or hyperphosphorylation can contribute to microtubule dysfunction and is associated with tau aggregation. In this review, we provide an overview of the structure and functions of tau protein as well as the physiologic roles of tau phosphorylation. We also extensively survey tau phosphorylation sites identified in brain tissue and cerebrospinal fluid from AD patients compared to age-matched healthy controls, which may serve as disease-specific biomarkers. Recently, new assays have been developed to measure minute amounts of specific forms of phosphorylated tau in both cerebrospinal fluid and plasma, which could potentially be useful for aiding clinical diagnosis and monitoring disease progression. Additionally, multiple therapies targeting phosphorylated tau are in various stages of clinical trials including kinase inhibitors, phosphatase activators, and tau immunotherapy. With promising early results, therapies that target phosphorylated tau could be useful at slowing tau hyperphosphorylation and aggregation in AD and other tauopathies.

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Alzheimer’s disease brain contains tau fractions with differential prion-like activities

Acta Neuropathologica Communications ◽

10.1186/s40478-021-01127-4 ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Longfei Li ◽

Ruirui Shi ◽

Jianlan Gu ◽

Yunn Chyn Tung ◽

Yan Zhou ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Cultured Cells ◽

Regional Distribution ◽

Proteinase K ◽

Hyperphosphorylated Tau ◽

Terminal Portion ◽

Tau Pathology ◽

Heat Stable ◽

Tau Aggregation

AbstractNeurofibrillary tangles (NFTs) made of abnormally hyperphosphorylated tau are a hallmark of Alzheimer’s disease (AD) and related tauopathies. Regional distribution of NFTs is associated with the progression of the disease and has been proposed to be a result of prion-like propagation of misfolded tau. Tau in AD brain is heterogenous and presents in various forms. In the present study, we prepared different tau fractions by sedimentation combined with sarkosyl solubility from AD brains and analyzed their biochemical and pathological properties. We found that tau in oligomeric fraction (O-tau), sarkosyl-insoluble fractions 1 and 2 (SI1-tau and SI2-tau) and monomeric heat-stable fraction (HS-tau) showed differences in truncation, hyperphosphorylation, and resistance to proteinase K. O-tau, SI1-tau, and SI2-tau, but not HS-tau, were hyperphosphorylated at multiple sites and contained SDS- and β-mercaptoethanol–resistant high molecular weight aggregates, which lacked the N-terminal portion of tau. O-tau and SI2-tau displayed more truncation and less hyperphosphorylation than SI1-tau. Resistance to proteinase K was increased from O-tau to SI1-tau to SI2-tau. O-tau and SI1-tau, but not SI2-tau or HS-tau, captured tau from cell lysates and seeded tau aggregation in cultured cells. Heat treatment could not kill the prion-like activity of O-tau to capture normal tau. Hippocampal injection of O-tau into 18-month-old FVB mice induced significant tau aggregation in both ipsilateral and contralateral hippocampi, but SI1-tau only induced tau pathology in the ipsilateral hippocampus, and SI2-tau and HS-tau failed to induce any detectable tau aggregation. These findings suggest that O-tau and SI1-tau have prion-like activities and may serve as seeds to recruit tau and template tau to aggregate, resulting in the propagation of tau pathology. Heterogeneity of tau pathology within AD brain results in different fractions with different biological and prion-like properties, which may pose a major challenge in targeting tau for development of effective therapeutic treatments.

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Aβ deposition is associated with increases in soluble and phosphorylated tau that precede a positive Tau PET in Alzheimer’s disease

Science Advances ◽

10.1126/sciadv.aaz2387 ◽

2020 ◽

Vol 6 (16) ◽

pp. eaaz2387 ◽

Cited By ~ 18

Author(s):

Niklas Mattsson-Carlgren ◽

Emelie Andersson ◽

Shorena Janelidze ◽

Rik Ossenkoppele ◽

Philip Insel ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Amyloid Pet ◽

Phosphorylated Tau ◽

Positron Emission ◽

Aβ Aggregation ◽

Tau Pet ◽

5Xfad Mice ◽

Tau Aggregation ◽

T Tau

The links between β-amyloid (Aβ) and tau in Alzheimer’s disease are unclear. Cognitively unimpaired persons with signs of Aβ pathology had increased cerebrospinal fluid (CSF) phosphorylated tau (P-tau181 and P-tau217) and total-tau (T-tau), which increased over time, despite no detection of insoluble tau aggregates [normal Tau positron emission tomography (PET)]. CSF P-tau and T-tau started to increase before the threshold for Amyloid PET positivity, while Tau PET started to increase after Amyloid PET positivity. Effects of Amyloid PET on Tau PET were mediated by CSF P-tau, and high CSF P-tau predicted increased Tau PET rates. Individuals with MAPT mutations and signs of tau deposition (but without Aβ pathology) had normal CSF P-tau levels. In 5xFAD mice, CSF tau increased when Aβ aggregation started. These results show that Aβ pathology may induce changes in soluble tau release and phosphorylation, which is followed by tau aggregation several years later in humans.

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Extensive Anti-CoA Immunostaining in Alzheimer’s Disease and Covalent Modification of Tau by a Key Cellular Metabolite Coenzyme A

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2021.739425 ◽

2021 ◽

Vol 15 ◽

Author(s):

Tammaryn Lashley ◽

Maria-Armineh Tossounian ◽

Neve Costello Heaven ◽

Samantha Wallworth ◽

Sew Peak-Chew ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Neurofibrillary Tangles ◽

Cellular Response ◽

Protein Modification ◽

Coenzyme A ◽

Neurodegenerative Disorder ◽

Regulation Of Gene Expression ◽

Covalent Modification

Alzheimer’s disease (AD) is a neurodegenerative disorder, accounting for at least two-thirds of dementia cases. A combination of genetic, epigenetic and environmental triggers is widely accepted to be responsible for the onset and development of AD. Accumulating evidence shows that oxidative stress and dysregulation of energy metabolism play an important role in AD pathogenesis, leading to neuronal dysfunction and death. Redox-induced protein modifications have been reported in the brain of AD patients, indicating excessive oxidative damage. Coenzyme A (CoA) is essential for diverse metabolic pathways, regulation of gene expression and biosynthesis of neurotransmitters. Dysregulation of CoA biosynthesis in animal models and inborn mutations in human genes involved in the CoA biosynthetic pathway have been associated with neurodegeneration. Recent studies have uncovered the antioxidant function of CoA, involving covalent protein modification by this cofactor (CoAlation) in cellular response to oxidative or metabolic stress. Protein CoAlation has been shown to both modulate the activity of modified proteins and protect cysteine residues from irreversible overoxidation. In this study, immunohistochemistry analysis with highly specific anti-CoA monoclonal antibody was used to reveal protein CoAlation across numerous neurodegenerative diseases, which appeared particularly frequent in AD. Furthermore, protein CoAlation consistently co-localized with tau-positive neurofibrillary tangles, underpinning one of the key pathological hallmarks of AD. Double immunihistochemical staining with tau and CoA antibodies in AD brain tissue revealed co-localization of the two immunoreactive signals. Further, recombinant 2N3R and 2N4R tau isoforms were found to be CoAlated in vitro and the site of CoAlation mapped by mass spectrometry to conserved cysteine 322, located in the microtubule binding region. We also report the reversible H2O2-induced dimerization of recombinant 2N3R, which is inhibited by CoAlation. Moreover, CoAlation of transiently expressed 2N4R tau was observed in diamide-treated HEK293/Pank1β cells. Taken together, this study demonstrates for the first time extensive anti-CoA immunoreactivity in AD brain samples, which occurs in structures resembling neurofibrillary tangles and neuropil threads. Covalent modification of recombinant tau at cysteine 322 suggests that CoAlation may play an important role in protecting redox-sensitive tau cysteine from irreversible overoxidation and may modulate its acetyltransferase activity and functional interactions.

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Bioavailability and Pharmaco-therapeutic Potential of Luteolin in Overcoming Alzheimer’s Disease

CNS & Neurological Disorders - Drug Targets ◽

10.2174/1871527318666190319141835 ◽

2019 ◽

Vol 18 (5) ◽

pp. 352-365 ◽

Cited By ~ 6

Author(s):

Fahad Ali ◽

Yasir Hasan Siddique

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Therapeutic Potential ◽

In Vivo Models ◽

Naturally Occurring ◽

Current Review ◽

Tau Aggregation ◽

Dose Limiting Toxicity

Luteolin is a naturally occurring, yellow crystalline flavonoid found in numerous dietary supplements we frequently have in our meals. Studies in the last 2 decades have revealed its therapeutic potential to reduce the Alzheimer’s disease (AD) symptoms in various in vitro and in vivo models. The anti-Alzheimer’s potential of luteolin is attributed to its ability to suppress Aβ as well as tau aggregation or promote their disaggregation, down-regulate the expression of COX-2, NOS, MMP-9, TNF-α, interleukins and chemokines, reduce oxidative stress by scavenging ROS, modulate the activities of transcription factors CREB, cJun, Nrf-1, NF-κB, p38, p53, AP-1 and β-catenine and inhibiting the activities of various protein kinases. In several systems, luteolin has been described as a potent antioxidant and anti-inflammatory agent. In addition, we have also discussed about the bio-availability of the luteolin in the plasma. After being metabolized luteolin persists in plasma as glucuronides and sulphate-conjugates. Human clinical trials indicated no dose limiting toxicity when administered at a dose of 100 mg/day. Improvements in the formulations and drug delivery systems may further enhance the bioavailability and potency of luteolin. The current review describes in detail the data supporting these studies.

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Aluminum and Tau in Neurofibrillary Tangles in Familial Alzheimer’s Disease

Journal of Alzheimer s Disease Reports ◽

10.3233/adr-210011 ◽

2021 ◽

pp. 1-12

Author(s):

Matthew John Mold ◽

Adam O’Farrell ◽

Benjamin Morris ◽

Christopher Exley

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Neurofibrillary Tangles ◽

Senile Plaques ◽

Amyloid Β ◽

Amyloid Β Protein ◽

Phosphorylated Tau ◽

Familial Alzheimer’S Disease ◽

Therapeutic Benefits ◽

Familial Alzheimer's Disease

Background: Familial Alzheimer’s disease (fAD) is driven by genetic predispositions affecting the expression and metabolism of the amyloid-β protein precursor. Aluminum is a non-essential yet biologically-reactive metal implicated in the etiology of AD. Recent research has identified aluminum intricately and unequivocally associated with amyloid-β in senile plaques and, more tentatively, co-deposited with neuropil-like threads in the brains of a Colombian cohort of donors with fAD. Objective: Herein, we have assessed the co-localization of aluminum to immunolabelled phosphorylated tau to probe the potential preferential binding of aluminum to senile plaques or neurofibrillary tangles in the same Colombian kindred. Methods: Herein, we have performed phosphorylated tau-specific immunolabelling followed by aluminum-specific fluorescence microscopy of the identical brain tissue sections via a sequential labelling method. Results: Aluminum was co-localized with immunoreactive phosphorylated tau in the brains of donors with fAD. While aluminum was predominantly co-located to neurofibrillary tangles in the temporal cortex, aluminum was more frequently co-deposited with cortical senile plaques. Conclusion: These data suggest that the co-deposition of aluminum with amyloid-β precedes that with neurofibrillary tangles. Extracellularly deposited amyloid-β may also be more immediately available to bind aluminum versus intracellular aggregates of tau. Therapeutic approaches to reduce tau have demonstrated the amelioration of its synergistic interactions with amyloid-β, ultimately reducing tau pathology and reducing neuronal loss. These data support the intricate associations of aluminum in the neuropathology of fAD, of which its subsequent reduction may further therapeutic benefits observed in ongoing clinical trials in vivo.

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Astrocytic expression of the Alzheimer’s disease risk allele, ApoEε4, potentiates neuronal tau pathology in multiple preclinical models

Scientific Reports ◽

10.1038/s41598-021-82901-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Angela Marie Jablonski ◽

Lee Warren ◽

Marija Usenovic ◽

Heather Zhou ◽

Jonathan Sugam ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Disease Risk ◽

In Vitro Models ◽

Tau Pathology ◽

Adeno Associated Virus ◽

Human Apoe ◽

Specific Effects ◽

Tau Aggregation

AbstractApoEε4 is a major genetic risk factor for Alzheimer’s disease (AD), a disease hallmarked by extracellular amyloid-beta (Aβ) plaques and intracellular neurofibrillary tangles (NFTs). The presence of the ApoEε4 allele is associated with increased Aβ deposition and a role for ApoEε4 in the potentiation of tau pathology has recently emerged. This study focused on comparing the effects of adeno-associated virus (AAV)-mediated overexpression of the three predominant human ApoE isoforms within astrocytes. The isoform-specific effects of human ApoE were evaluated within in vitro models of tau pathology within neuron/astrocyte co-cultures, as well as in a transgenic tau mouse model. Tau aggregation, accumulation, and phosphorylation were measured to determine if the three isoforms of human ApoE had differential effects on tau. Astrocytic overexpression of the human ApoEε4 allele increased phosphorylation and misfolding of overexpressed neuronal tau in multiple models, including the aggregation and accumulation of added tau oligomers, in an isoform-specific manner. The ability of ApoEε4 to increase tau aggregation could be inhibited by an ApoEε4-specific antibody. This study indicates that astrocytic expression of ApoEε4 can potentiate tau aggregation and phosphorylation within neurons and supports a gain of toxic function hypothesis for the effect of hApoEε4 on tau.

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Cinnamon Extract Inhibits Tau Aggregation Associated with Alzheimer's Disease In Vitro

Journal of Alzheimer s Disease ◽

10.3233/jad-2009-1083 ◽

2009 ◽

Vol 17 (3) ◽

pp. 585-597 ◽

Cited By ~ 63

Author(s):

Dylan W. Peterson ◽

Roshni C. George ◽

Francesca Scaramozzino ◽

Nichole E. LaPointe ◽

Richard A. Anderson ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Cinnamon Extract ◽

Tau Aggregation

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Phosphorylated tau interactome in the human Alzheimer’s disease brain

Brain ◽

10.1093/brain/awaa223 ◽

2020 ◽

Vol 143 (9) ◽

pp. 2803-2817 ◽

Cited By ~ 1

Author(s):

Eleanor Drummond ◽

Geoffrey Pires ◽

Claire MacMurray ◽

Manor Askenazi ◽

Shruti Nayak ◽

...

Keyword(s):

Mass Spectrometry ◽

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Neurofibrillary Tangles ◽

Affinity Purification ◽

Pathological Feature ◽

Phosphorylated Tau ◽

Atpase Subunit ◽

Protein Ubiquitination ◽

Affinity Purification Mass Spectrometry

Abstract Accumulation of phosphorylated tau is a key pathological feature of Alzheimer’s disease. Phosphorylated tau accumulation causes synaptic impairment, neuronal dysfunction and formation of neurofibrillary tangles. The pathological actions of phosphorylated tau are mediated by surrounding neuronal proteins; however, a comprehensive understanding of the proteins that phosphorylated tau interacts with in Alzheimer’s disease is surprisingly limited. Therefore, the aim of this study was to determine the phosphorylated tau interactome. To this end, we used two complementary proteomics approaches: (i) quantitative proteomics was performed on neurofibrillary tangles microdissected from patients with advanced Alzheimer’s disease; and (ii) affinity purification-mass spectrometry was used to identify which of these proteins specifically bound to phosphorylated tau. We identified 542 proteins in neurofibrillary tangles. This included the abundant detection of many proteins known to be present in neurofibrillary tangles such as tau, ubiquitin, neurofilament proteins and apolipoprotein E. Affinity purification-mass spectrometry confirmed that 75 proteins present in neurofibrillary tangles interacted with PHF1-immunoreactive phosphorylated tau. Twenty-nine of these proteins have been previously associated with phosphorylated tau, therefore validating our proteomic approach. More importantly, 34 proteins had previously been associated with total tau, but not yet linked directly to phosphorylated tau (e.g. synaptic protein VAMP2, vacuolar-ATPase subunit ATP6V0D1); therefore, we provide new evidence that they directly interact with phosphorylated tau in Alzheimer’s disease. In addition, we also identified 12 novel proteins, not previously known to be physiologically or pathologically associated with tau (e.g. RNA binding protein HNRNPA1). Network analysis showed that the phosphorylated tau interactome was enriched in proteins involved in the protein ubiquitination pathway and phagosome maturation. Importantly, we were able to pinpoint specific proteins that phosphorylated tau interacts with in these pathways for the first time, therefore providing novel potential pathogenic mechanisms that can be explored in future studies. Combined, our results reveal new potential drug targets for the treatment of tauopathies and provide insight into how phosphorylated tau mediates its toxicity in Alzheimer’s disease.

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