scholarly journals Ageing and amyloidosis underlie the molecular and pathological alterations of tau in a mouse model of familial Alzheimer’s disease

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Athanasios Metaxas ◽  
Camilla Thygesen ◽  
Stefan J. Kempf ◽  
Marco Anzalone ◽  
Ramanan Vaitheeswaran ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Human Subjects ◽  
Experimental Models ◽  
Mouse Tissue ◽  
Tau Pathology ◽  
Cerebral Amyloidosis ◽  
Necessary And Sufficient ◽  
Tau Aggregation ◽  
Tau Aggregate

Abstract Despite compelling evidence that the accumulation of amyloid-beta (Aβ) promotes neocortical MAPT (tau) aggregation in familial and idiopathic Alzheimer’s disease (AD), murine models of cerebral amyloidosis are not considered to develop tau-associated pathology. In the present study, we show that tau can accumulate spontaneously in aged transgenic APPswe/PS1ΔE9 mice. Tau pathology is abundant around Aβ deposits, and further characterized by accumulation of Gallyas and thioflavin-S-positive inclusions, which were detected in the APPswe/PS1ΔE9 brain at 18 months of age. Age-dependent increases in argyrophilia correlated positively with binding levels of the paired helical filament (PHF) tracer [18F]Flortaucipir, in all brain areas examined. Sarkosyl-insoluble PHFs were visualized by electron microscopy. Quantitative proteomics identified sequences of hyperphosphorylated and three-repeat tau in transgenic mice, along with signs of RNA missplicing, ribosomal dysregulation and disturbed energy metabolism. Tissue from the frontal gyrus of human subjects was used to validate these findings, revealing primarily quantitative differences between the tau pathology observed in AD patient vs. transgenic mouse tissue. As physiological levels of endogenous, ‘wild-type’ tau aggregate secondarily to Aβ in APPswe/PS1ΔE9 mice, this study suggests that amyloidosis is both necessary and sufficient to drive tauopathy in experimental models of familial AD.

scholarly journals Tauopathy in theAPPswe/PS1ΔE9mouse model of familial Alzheimer’s disease

2018 ◽  
Author(s):  
Athanasios Metaxas ◽  
Camilla Thygesen ◽  
Stefan J. Kempf ◽  
Marco Anzalone ◽  
Ramanan Vaitheeswaran ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Transgenic Mice ◽  
Experimental Models ◽  
Mouse Tissue ◽  
Murine Models ◽  
Littermate Control ◽  
Cerebral Amyloidosis ◽  
Necessary And Sufficient ◽  
Tau Aggregation

AbstractDespite compelling evidence that the accumulation of amyloid-beta (Aβ) promotes cortical MAPT (tau) aggregation in familial and idiopathic Alzheimer’s disease (AD), murine models of cerebral amyloidosis are not considered to develop tau-associated pathology. The absence of neurofibrillary lesions in amyloidosis mice remains a challenge for the amyloidocentric paradigm of AD pathogenesis. It has resulted in the generation of transgenic mice harboring mutations in theirtaugene, which may be inappropriate for studying a disease with no knownTAUmutations, such as AD. Here, we have usedAPPswe/PS1ΔE9mice to show that tau pathology can develop spontaneously in murine models of familial AD. Tauopathy was abundant around Aβ deposits, with Gallyas- and thioflavin-S-positive perinuclear inclusions accumulating in theAPPswe/PS1ΔE9cortex by 18 months of age. Age-dependent increases in Gallyas signal correlated positively with binding levels of the paired helical filament (PHF) ligand [18F]Flortaucipir, in all brain areas examined. Sarkosyl-insoluble PHFs were visualized by electron microscopy. Tandem mass tag proteomics identified sequences of hyperphosphorylated tau in transgenic mice, along with signs of RNA missplicing, ribosomal dysregulation and disturbed energy metabolism. Human frontal gyrus tissue was used to validate these findings, revealing primarily quantitative differences between the tauopathy observed in AD patient vs. transgenic mouse tissue. Levels oftaumRNA were not different betweenAPPswe/PS1ΔE9and littermate control animals. As physiological levels of endogenous, ‘wild-type’ tau aggregate secondarily to Aβ in transgenic mice, this study demonstrates that amyloidosis is both necessary and sufficient to drive tauopathy in experimental models of familial AD.

scholarly journals The extracellular chaperone Clusterin enhances Tau aggregate seeding in a cellular model

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Patricia Yuste-Checa ◽  
Victoria A. Trinkaus ◽  
Irene Riera-Tur ◽  
Rahmi Imamoglu ◽  
Theresa F. Schaller ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Disease Progression ◽  
Frontotemporal Dementia ◽  
Brain Regions ◽  
Model System ◽  
Cellular Model ◽  
Tau Pathology ◽  
Extracellular Chaperone ◽  
Tau Aggregate

AbstractSpreading of aggregate pathology across brain regions acts as a driver of disease progression in Tau-related neurodegeneration, including Alzheimer’s disease (AD) and frontotemporal dementia. Aggregate seeds released from affected cells are internalized by naïve cells and induce the prion-like templating of soluble Tau into neurotoxic aggregates. Here we show in a cellular model system and in neurons that Clusterin, an abundant extracellular chaperone, strongly enhances Tau aggregate seeding. Upon interaction with Tau aggregates, Clusterin stabilizes highly potent, soluble seed species. Tau/Clusterin complexes enter recipient cells via endocytosis and compromise the endolysosomal compartment, allowing transfer to the cytosol where they propagate aggregation of endogenous Tau. Thus, upregulation of Clusterin, as observed in AD patients, may enhance Tau seeding and possibly accelerate the spreading of Tau pathology.

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

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.

scholarly journals Alzheimer’s Disease risk modifier genes do not impact tau aggregate uptake, seeding or maintenance in cell models

2019 ◽  
Author(s):  
Sourav Kolay ◽  
Marc I. Diamond
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Gene Knockout ◽  
Association Studies ◽  
Modifier Genes ◽  
Model Systems ◽  
Genome Wide Association Studies ◽  
Tau Pathology ◽  
Risk Modifier ◽  
Tau Aggregate

ABSTRACTAlzheimer’s disease (AD) afflicts millions of people worldwide, and is caused by accumulated amyloid beta and tau pathology. Progression of tau pathology in AD may utilize prion mechanisms of propagation in which pathological tau aggregates released from one cell are taken up by neighboring or connected cells and act as templates for their own replication, a process termed “seeding.” In cultured cells we have modeled various aspects of pathological tau propagation, including uptake of aggregates, induced (naked) seeding by exogenous aggregates, seeding caused by Lipofectamine-mediated delivery to the cell interior, and chronic maintenance of aggregates in cells through mother-to-daughter transmission. The factors that regulate these processes are not well understood, and we hypothesized that AD risk modifier genes might play a role. We identified 22 genes strongly linked to AD via meta-analysis of genome-wide association studies (GWAS). We used CRISPR/Cas-9 to individually knock out each in gene in HEK293T cells, and verified disruption using genomic sequencing. We then tested the effect of gene knockout in tau aggregate uptake, naked and Lipofectamine-mediated seeding, and aggregate maintenance in cultured cell lines. GWAS gene knockouts had no effect on these models of tau pathology. With obvious caveats due to the model systems used, these results imply that these 22 AD risk modifier genes do not directly modulate tau uptake, seeding, or aggregate maintenance.

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

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.

Neuroinflammation in Alzheimer’s disease: focus on NLRP1 and NLRP3 inflammasomes

2021 ◽  
Vol 22 ◽  
Author(s):  
Eliana Cristina de Brito Toscano ◽  
Natalia Pessoa Rocha ◽  
Beatriz Noele Azevedo Lopes ◽  
Claudia Kimie Suemoto ◽  
Antonio Lucio Teixeira
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Β ◽  
Experimental Models ◽  
Tau Pathology ◽  
Relevant Role ◽  
Nlrp3 Inflammasomes ◽  
Amyloid Cascade ◽  
Disease Focus

Background: Alzheimer’s disease (AD) is the main cause of dementia worldwide. The definitive diagnosis of AD is clinicopathological and based on the identification of cerebral deposition of amyloid β (Aβ) plaques and neurofibrillary tangles. However, the link between amyloid cascade and depositions of phosphorylated tau (p-tau) is still missing. In this scenario, inflammasomes might play a relevant role. Experimental models of AD have suggested that Aβ accumulation induces, through microglia, activation of the NLRP3 inflammasome. This activation contributes to the dissemination of Aβ and p-tau, as well as to hyperphosphorylation of tau. Also in experimental models, NLPR1 promoted neuronal pyroptosis. There are neither comprehensive neuropathologic characterization, nor clinicopathologic studies evaluating the NLRP1 and NLRP3 inflammasomes in subjects with AD. Objective: The current mini-review aims to summarize recent and promising findings on the role of NLRP1 and NLRP3 signaling in the pathophysiology of AD. We also sought to highlight the knowledge gap in patients with AD, mainly the lack of clinicopathologic studies on the interaction among inflammasomes, Aβ/tau pathology, and cognitive decline.

scholarly journals Delta-secretase cleavage of Tau mediates its pathology and propagation in Alzheimer’s disease

2020 ◽  
Vol 52 (8) ◽  
pp. 1275-1287
Author(s):  
Seong Su Kang ◽  
Eun Hee Ahn ◽  
Keqiang Ye
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Therapeutic Strategy ◽  
Senile Plaques ◽  
Tau Pathology ◽  
Disease Modifying ◽  
Tau Aggregation ◽  
The Brain ◽  
Insight Into

Abstract Alzheimer’s disease (AD) is a progressive neurodegenerative disease with age as a major risk factor. AD is the most common dementia with abnormal structures, including extracellular senile plaques and intraneuronal neurofibrillary tangles, as key neuropathologic hallmarks. The early feature of AD pathology is degeneration of the locus coeruleus (LC), which is the main source of norepinephrine (NE) supplying various cortical and subcortical areas that are affected in AD. The spread of Tau deposits is first initiated in the LC and is transported in a stepwise manner from the entorhinal cortex to the hippocampus and then to associative regions of the neocortex as the disease progresses. Most recently, we reported that the NE metabolite DOPEGAL activates delta-secretase (AEP, asparagine endopeptidase) and triggers pathological Tau aggregation in the LC, providing molecular insight into why LC neurons are selectively vulnerable to developing early Tau pathology and degenerating later in the disease and how δ-secretase mediates the spread of Tau pathology to the rest of the brain. This review summarizes our current understanding of the crucial role of δ-secretase in driving and spreading AD pathologies by cleaving multiple critical players, including APP and Tau, supporting that blockade of δ-secretase may provide an innovative disease-modifying therapeutic strategy for treating AD.

scholarly journals Quantitative propagation of assembled human Tau from Alzheimer's disease brain in microfluidic neuronal cultures

2020 ◽  
Vol 295 (37) ◽  
pp. 13079-13093 ◽  
Author(s):  
Antigoni Katsikoudi ◽  
Elena Ficulle ◽  
Annalisa Cavallini ◽  
Gary Sharman ◽  
Amelie Guyot ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Imaging Techniques ◽  
Therapeutic Interventions ◽  
Neuronal Cultures ◽  
Tau Pathology ◽  
High Content Imaging ◽  
Molecule Inhibitor ◽  
Culture Model ◽  
Tau Aggregation

Tau aggregation and hyperphosphorylation is a key neuropathological hallmark of Alzheimer's disease (AD), and the temporospatial spread of Tau observed during clinical manifestation suggests that Tau pathology may spread along the axonal network and propagate between synaptically connected neurons. Here, we have developed a cellular model that allows the study of human AD-derived Tau propagation from neuron to neuron using microfluidic devices. We show by using high-content imaging techniques and an in-house developed interactive computer program that human AD-derived Tau seeds rodent Tau that propagates trans-neuronally in a quantifiable manner in a microfluidic culture model. Moreover, we were able to convert this model to a medium-throughput format allowing the user to handle 16 two-chamber devices simultaneously in the footprint of a standard 96-well plate. Furthermore, we show that a small molecule inhibitor of aggregation can block the trans-neuronal transfer of Tau aggregates, suggesting that the system can be used to evaluate mechanisms of Tau transfer and find therapeutic interventions.

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