A TauP301L mouse model of dementia; development of pathology, synaptic transmission, microglial response and cognition throughout life

AbstractBackgroundLate stage Alzheimer’s disease and other dementias are associated with neurofibrillary tangles and neurodegeneration. Here we describe a mouse (TauD35) carrying human Tau with the P301L mutation that results in Tau hyperphosphorylation and tangles. Previously we have compared gene expression in TauD35 mice to mice which develop plaques but no tangles. A similar comparison of other pathological features throughout disease progression is made here between amyloidβ and Tau mice described in Parts I and II of this study.MethodsIn vitro CA1 patch clamp and field recordings were used to investigate synaptic transmission and plasticity. Plaque load and microglia were investigated with immunohistochemistry. Cognition, locomotor activity and anxiety-related behaviours were assessed with a forced-alternation T-maze, open field and light/dark box.ResultsTransgene copy number in TauD35 mice fell into two groups (HighTAU and LowTAU), allowing assessment of dose-dependent effects of overexpression and resulting in tangle load increasing 100-fold for a 2-fold change in protein levels. Tangles were first detected at 8 (HighTAU) or 13 months (LowTAU) but the effects on synaptic transmission and plasticity and behaviour were subtle. However, severe neurodegeneration occurred in HighTAU mice at around 17 months, preceded by considerable proliferation and activation of microglia at 13 months of age; both increasing further at 17 months. LowTAU mice at 24 months of age showed a comparable tangle load and microglial proliferation to that occurring at 13 months in HighTAU mice. However, LowTAU mice showed no neurodegeneration at this stage and considerable microglial activation, stressing the dependence of these effects on overexpression and/or age.ConclusionsComparison of the effects of amyloidβ and plaques without tangles in a model of preclinical Alzheimer’s disease to the effects of tangles without amyloidβ plaques in the late stage model described here may clarify the progressive stages of Alzheimer’s disease. While Tau hyperphosphorylation and neurofibrillary tangles are eventually sufficient to cause severe neurodegeneration, initial effects on synaptic transmission and the immune response are subtle. In contrast while even with a heavy plaque load little if any neurodegeneration occurs, considerable effects on synaptic transmission and the immune system result, even before plaques are detectable.

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Escitalopram Alleviates Alzheimer’s Disease-Type Tau Pathologies in the Aged P301L Tau Transgenic Mice

Journal of Alzheimer s Disease ◽

10.3233/jad-200401 ◽

2020 ◽

Vol 77 (2) ◽

pp. 807-819

Author(s):

Yan-Juan Wang ◽

Wei-Gang Gong ◽

Qing-Guo Ren ◽

Zhi-Jun Zhang

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Tau Phosphorylation ◽

Tau Hyperphosphorylation ◽

Protective Effects ◽

Protein Levels ◽

Phosphorylated Akt ◽

Biochemical Analyses ◽

Gsk 3Β

Background: The inhibition of tau hyperphosphorylation is one of the most promising therapeutic targets for the development of Alzheimer’s disease (AD) modifying drugs. Escitalopram, a kind of selective serotonin reuptake inhibitor antidepressant, has been previously reported to ameliorate tau hyperphosphorylation in vitro. Objective: In this study, we determined whether escitalopram alleviates tau pathologies in the aged P301L mouse. Methods: Mice were intraperitoneal injected with either escitalopram or saline for 4 weeks, and a battery of behavioral tests were conducted before tissue collection and biochemical analyses of brain tissue with western blot and immunohistochemistry. Results: Wild-type (Wt) mice statistically outperformed the aged pR5 mice in the Morris water maze, while escitalopram treatment did not significantly rescue learning and memory deficits of aged pR5 mice. Tau phosphorylation at different phosphorylation sites were enhanced in the hippocampus of aged pR5 mice, while escitalopram treatment significantly decreased tau phosphorylation. The levels of phosphorylated GSK-3β and phosphorylated Akt were significantly decreased in the hippocampus of aged pR5 mice, while escitalopram administration markedly increased the expression level. The aged pR5 mice showed significant decreases in PSD95 and PSD93, while the administration of escitalopram significantly increased PSD95 and PSD93 to levels comparable with the Wt mice. Conclusion: The protective effects of escitalopram exposure during advanced AD are mainly associated with significant decrease in tau hyperphosphorylation, increased numbers of neurons, and increased synaptic protein levels, which may via activation of the Akt/GSK-3β signaling pathway.

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Targeting Tau Hyperphosphorylation via Kinase Inhibition: Strategy to Address Alzheimer's Disease

Current Topics in Medicinal Chemistry ◽

10.2174/1568026620666200106125910 ◽

2020 ◽

Vol 20 (12) ◽

pp. 1059-1073 ◽

Cited By ~ 3

Author(s):

Ahmad Abu Turab Naqvi ◽

Gulam Mustafa Hasan ◽

Md. Imtaiyaz Hassan

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Tau Protein ◽

Glycogen Synthase ◽

Paired Helical Filaments ◽

Tau Hyperphosphorylation ◽

Microtubule Stabilization ◽

Extracellular Signal

Microtubule-associated protein tau is involved in the tubulin binding leading to microtubule stabilization in neuronal cells which is essential for stabilization of neuron cytoskeleton. The regulation of tau activity is accommodated by several kinases which phosphorylate tau protein on specific sites. In pathological conditions, abnormal activity of tau kinases such as glycogen synthase kinase-3 β (GSK3β), cyclin-dependent kinase 5 (CDK5), c-Jun N-terminal kinases (JNKs), extracellular signal-regulated kinase 1 and 2 (ERK1/2) and microtubule affinity regulating kinase (MARK) lead to tau hyperphosphorylation. Hyperphosphorylation of tau protein leads to aggregation of tau into paired helical filaments like structures which are major constituents of neurofibrillary tangles, a hallmark of Alzheimer’s disease. In this review, we discuss various tau protein kinases and their association with tau hyperphosphorylation. We also discuss various strategies and the advancements made in the area of Alzheimer's disease drug development by designing effective and specific inhibitors for such kinases using traditional in vitro/in vivo methods and state of the art in silico techniques.

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RTP801/REDD1 contributes to neuroinflammation severity and memory impairments in Alzheimer’s disease

Cell Death and Disease ◽

10.1038/s41419-021-03899-y ◽

2021 ◽

Vol 12 (6) ◽

Author(s):

Leticia Pérez-Sisqués ◽

Anna Sancho-Balsells ◽

Júlia Solana-Balaguer ◽

Genís Campoy-Campos ◽

Marcel Vives-Isern ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Hippocampal Neurons ◽

Mrna Levels ◽

Spine Density ◽

Memory Impairments ◽

Protein Levels ◽

Synaptic Markers ◽

5Xfad Mice

AbstractRTP801/REDD1 is a stress-regulated protein whose upregulation is necessary and sufficient to trigger neuronal death. Its downregulation in Parkinson’s and Huntington’s disease models ameliorates the pathological phenotypes. In the context of Alzheimer’s disease (AD), the coding gene for RTP801, DDIT4, is responsive to Aβ and modulates its cytotoxicity in vitro. Also, RTP801 mRNA levels are increased in AD patients’ lymphocytes. However, the involvement of RTP801 in the pathophysiology of AD has not been yet tested. Here, we demonstrate that RTP801 levels are increased in postmortem hippocampal samples from AD patients. Interestingly, RTP801 protein levels correlated with both Braak and Thal stages of the disease and with GFAP expression. RTP801 levels are also upregulated in hippocampal synaptosomal fractions obtained from murine 5xFAD and rTg4510 mice models of the disease. A local RTP801 knockdown in the 5xFAD hippocampal neurons with shRNA-containing AAV particles ameliorates cognitive deficits in 7-month-old animals. Upon RTP801 silencing in the 5xFAD mice, no major changes were detected in hippocampal synaptic markers or spine density. Importantly, we found an unanticipated recovery of several gliosis hallmarks and inflammasome key proteins upon neuronal RTP801 downregulation in the 5xFAD mice. Altogether our results suggest that RTP801 could be a potential future target for theranostic studies since it could be a biomarker of neuroinflammation and neurotoxicity severity of the disease and, at the same time, a promising therapeutic target in the treatment of AD.

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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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Plant Compound Curcumin Mediates Calcineurin Activity to Upregulate ABCA1 Expression in a Model of Alzheimer’s Disease

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1120-1121.821 ◽

2015 ◽

Vol 1120-1121 ◽

pp. 821-825

Author(s):

Ke Xu ◽

Xiong Zhang ◽

Li Yu

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Cholesterol Metabolism ◽

Protein Levels ◽

Atp Binding Cassette Transporter ◽

Model Of Alzheimer’S Disease ◽

Abca1 Expression ◽

Underlying Mechanisms ◽

Calcineurin Activity

Cholesterol metabolism plays an important role in pathogenesis of Alzheimer’s disease (AD). Curcumin has been reported to decrease cholesterol in serum through increasing the cholesterol efflux transporter ATP-binding cassette transporter A1 (ABCA1) expression, but the underlying mechanisms are not fully understand yet. To investigate the effects of curcumin on the activity of calcineurin and the expression of ABCA1 in vitro, N2a/APP695swe cells were treated with curcumin at 5 umol/L for 24 h, or with the calcineurin activity inhabitor CyclosporinA (CsA) at 0.5 umol/L for 48 h. Our findings showed that curcumin could increase the expression of the ABCA1 at mRNA and protein levels, furthermore, it could inhibit the calcineurin activity, CsA also could increase the expression of the ABCA1 at mRNA and protein levels. These findings suggest that curcumin may upregulate the expression of ABCA1 via inhibiting the calcineurin activity in N2a/APP695swe cells.

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Exploration of Aberrant E3 Ligases Implicated in Alzheimer’s Disease and Development of Chemical Tools to Modulate Their Function

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2021.768655 ◽

2021 ◽

Vol 15 ◽

Author(s):

Frances M. Potjewyd ◽

Alison D. Axtman

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

E3 Ligase ◽

Amyloid Β ◽

3D Cell Culture ◽

Ubiquitin Proteasome System ◽

E3 Ligases ◽

Protein Levels ◽

Chemical Tools

The Ubiquitin Proteasome System (UPS) is responsible for the degradation of misfolded or aggregated proteins via a multistep ATP-dependent proteolytic mechanism. This process involves a cascade of ubiquitin (Ub) transfer steps from E1 to E2 to E3 ligase. The E3 ligase transfers Ub to a targeted protein that is brought to the proteasome for degradation. The inability of the UPS to remove misfolded or aggregated proteins due to UPS dysfunction is commonly observed in neurodegenerative diseases, such as Alzheimer’s disease (AD). UPS dysfunction in AD drives disease pathology and is associated with the common hallmarks such as amyloid-β (Aβ) accumulation and tau hyperphosphorylation, among others. E3 ligases are key members of the UPS machinery and dysfunction or changes in their expression can propagate other aberrant processes that accelerate AD pathology. The upregulation or downregulation of expression or activity of E3 ligases responsible for these processes results in changes in protein levels of E3 ligase substrates, many of which represent key proteins that propagate AD. A powerful way to better characterize UPS dysfunction in AD and the role of individual E3 ligases is via the use of high-quality chemical tools that bind and modulate specific E3 ligases. Furthermore, through combining gene editing with recent advances in 3D cell culture, in vitro modeling of AD in a dish has become more relevant and possible. These cell-based models of AD allow for study of specific pathways and mechanisms as well as characterization of the role E3 ligases play in driving AD. In this review, we outline the key mechanisms of UPS dysregulation linked to E3 ligases in AD and highlight the currently available chemical modulators. We present several key approaches for E3 ligase ligand discovery being employed with respect to distinct classes of E3 ligases. Where possible, specific examples of the use of cultured neurons to delineate E3 ligase biology have been captured. Finally, utilizing the available ligands for E3 ligases in the design of proteolysis targeting chimeras (PROTACs) to degrade aberrant proteins is a novel strategy for AD, and we explore the prospects of PROTACs as AD therapeutics.

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USP14 haploinsufficiency ameliorates Alzheimer’s disease-like pathology in APP/PS1 mice

10.21203/rs.3.rs-84968/v1 ◽

2020 ◽

Author(s):

Hua Xu ◽

Xueheng Wu ◽

Lu Liang ◽

Haoyu Chen ◽

Jia Xu ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Neurofibrillary Tangles ◽

Senile Plaques ◽

Ubiquitin Proteasome System ◽

Spatial Learning And Memory ◽

Protein Levels ◽

Reported Study ◽

Ubiquitin Proteasome ◽

The Impact

Abstract Background: Alzheimer's disease (AD) is the most common cause of dementia; its main pathological features are neurofibrillary tangles (NFTs) consisting of hyperphosphorylated microtubule-associated protein (Tau) in the cell and extracellular beta-amyloid protein (Aβ)-based senile plaques (SP). The ubiquitin-proteasome system (UPS) is the main pathway for protein degradation in cells. Proteasome malfunction exists in AD patients and may promote the progression of the disease. USP14 is a deubiquitinating enzyme associated with the 19S proteasome. Functional inhibition of USP14 was shown to enhance proteasome proteolytic function, but no reported study has investigated the impact of genetic inhibition of USP14 on AD.Methods: Mice with heterozygous knockout of the Usp14 gene (USP14+/-) were generated and cross-bred with the APP/PS1 transgenic mice, the resultant offspring littermates were subjected to basal survival and growth analyses, and comparison of AD-like pathologies as detected with biochemical and histopathological methods and of cognitive function as assessed with the Morris water maze tests. Results:USP14 mRNA and protein levels in USP14+/- mice were decreased by ~50% compared with USP14+/+mice. The increases of total, K48 or K63 linked ubiquitinated proteins in APP/PS1 mouse brains were abolished in APP/PS1::USP14+/- mice. The increases in Aβ deposition and AD-associated phosphorylated Tau, senile plagues and neurofibrillary tangles, as well as spatial learning and memory decline induced by APP/PS1 were significantly attenuated in APP/PS1 mice. Conclusions: This study demonstrates that global knocking down USP14 protein expression by 50% is tolerable by mice and exhibits marked protection against AD-like pathologies in a widely used AD mouse model, favoring the exploration of moderate inhibition ofUSP14 as a potentially novel and viable therapy against AD.

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USP14 Haploinsufficiency Ameliorates Alzheimer’s Disease-Like Pathology in APP/PS1 Mice

10.21203/rs.3.rs-68805/v1 ◽

2020 ◽

Author(s):

Hua Xu ◽

Xueheng Wu ◽

Lu Liang ◽

Haoyu Chen ◽

Jia Xu ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Neurofibrillary Tangles ◽

Senile Plaques ◽

Ubiquitin Proteasome System ◽

Spatial Learning And Memory ◽

Protein Levels ◽

Reported Study ◽

Ubiquitin Proteasome ◽

The Impact

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Pathology of the Cleaved Tau Protein in the Context of Toxicity and the Formation of Neurofibrillary Tangles

European Neurological Review ◽

10.17925/enr.2009.04.02.20 ◽

2009 ◽

Vol 4 (2) ◽

pp. 20

Author(s):

Gustavo Basurto Islas ◽

Siddhartha Mondragón Rodríguez ◽

Lester I Binder ◽

Francisco García-Sierra ◽

◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Neurofibrillary Tangles ◽

Tau Protein ◽

Intracellular Transport ◽

Neuronal Degeneration ◽

Binding Capacity ◽

Neurofibrillary Tangle ◽

Oligomeric State

In Alzheimer’s disease, tau protein is abnormally processed to self-aggregate into pathologically paired helical filaments and neurofibrillary tangles. Accumulation of these structures in the somatodendritic compartment of neurons may result in pathological alterations of the cytoskeleton stability, abnormal sorting of molecules and obstruction of the intracellular transport of organelles. Initially, abnormal phosphorylation of tau was considered by many to be the major modification that alters its microtubule-binding capacity. In recent years, however, proteolytic cleavage of tau protein produced by caspases has been shown to promote the abnormal aggregation properties of tauin vitroand to produce toxic effects in cell and animal models of Alzheimer's disease. Although some of these results have been debated, truncation of tau associated with neurofibrillary tangle formation has been shown to correlate well with the clinical progression of Alzheimer’s disease. Although new alternative mechanisms of tau pathogenesis in a monomeric or oligomeric state have been proposed, the aggregated form of intact or truncated tau into insoluble polymers is still a major indicator of neuronal degeneration.

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Autosomal dominant VCP hypomorph mutation impairs disaggregation of PHF-tau

Science ◽

10.1126/science.aay8826 ◽

2020 ◽

Vol 370 (6519) ◽

pp. eaay8826 ◽

Cited By ~ 2

Author(s):

Nabil F. Darwich ◽

Jessica M. Phan ◽

Boram Kim ◽

EunRan Suh ◽

John D. Papatriantafyllou ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Neurofibrillary Tangles ◽

Therapeutic Target ◽

Autosomal Dominant ◽

Genetic Mutation ◽

Neurofibrillary Degeneration ◽

Wild Type ◽

Intracerebral Microinjection

Neurodegeneration in Alzheimer’s disease (AD) is closely associated with the accumulation of pathologic tau aggregates in the form of neurofibrillary tangles. We found that a p.Asp395Gly mutation in VCP (valosin-containing protein) was associated with dementia characterized neuropathologically by neuronal vacuoles and neurofibrillary tangles. Moreover, VCP appeared to exhibit tau disaggregase activity in vitro, which was impaired by the p.Asp395Gly mutation. Additionally, intracerebral microinjection of pathologic tau led to increased tau aggregates in mice in which p.Asp395Gly VCP mice was knocked in, as compared with injected wild-type mice. These findings suggest that p.Asp395Gly VCP is an autosomal-dominant genetic mutation associated with neurofibrillary degeneration in part owing to reduced tau disaggregation, raising the possibility that VCP may represent a therapeutic target for the treatment of AD.

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