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de Veij Mestdagh CF, Witte ME, Scheper W, Smit AB, Henning RH, van Kesteren RE. Torpor induces reversible tau hyperphosphorylation and accumulation in mice expressing human tau. Acta Neuropathol Commun 2024; 12:86. [PMID: 38835043 PMCID: PMC11149198 DOI: 10.1186/s40478-024-01800-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Accepted: 05/13/2024] [Indexed: 06/06/2024] Open
Abstract
Tau protein hyperphosphorylation and aggregation are key pathological events in neurodegenerative tauopathies such as Alzheimer's disease. Interestingly, seasonal hibernators show extensive tau hyperphosphorylation during torpor, i.e., the hypothermic and hypometabolic state of hibernation, which is completely reversed during arousal. Torpor-associated mechanisms that reverse tau hyperphosphorylation may be of therapeutic relevance, however, it is currently not known to what extent they apply to human tau. Here we addressed this issue using daily torpor in wildtype mice that express mouse tau (mtau) and in mice that lack mtau expression and instead express human tau (htau). AT8, AT100 and Ser396 immunoblotting and immunohistochemistry were used to assess tau (hyper)phosphorylation at clinically relevant phosphorylation sites. We found that torpor robustly and reversibly increases the levels of phosphorylated tau in both mtau and htau mice. Immunohistochemistry revealed four brain areas that show prominent tau phosphorylation: the hippocampus, posterior parietal cortex, piriform cortex and cortical amygdala. Whereas wildtype mice primarily showed increased levels of diffusely organized hyperphosphorylated tau during torpor, htau mice contained clear somato-dendritic accumulations of AT8 reactivity resembling tau pre-tangles as observed in the Alzheimer brain. Interestingly, AT8-positive accumulations disappeared upon arousal, and tau phosphorylation levels at 24 h after arousal were lower than observed at baseline, suggesting a beneficial effect of torpor-arousal cycles on preexisting hyperphosphorylated tau. In conclusion, daily torpor in mice offers a quick and standardized method to study tau phosphorylation, accumulation and clearance in mouse models relevant for neurodegeneration, as well as opportunities to discover new targets for the treatment of human tauopathies.
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Affiliation(s)
- C F de Veij Mestdagh
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, Groningen, The Netherlands.
- Alzheimer Center Amsterdam, Amsterdam UMC location VUmc, Amsterdam, The Netherlands.
| | - M E Witte
- Department of Molecular Cell Biology and Immunology, MS Center, Amsterdam UMC location VUmc, Amsterdam, The Netherlands
| | - W Scheper
- Department of Human Genetics, Amsterdam UMC - location Vrije Universiteit, Amsterdam, The Netherlands
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - A B Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - R H Henning
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, Groningen, The Netherlands
| | - R E van Kesteren
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
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2
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Jiang S, Sydney EJ, Runyan AM, Serpe R, Srikanth M, Figueroa HY, Yang M, Myeku N. 5-HT4 receptor agonists treatment reduces tau pathology and behavioral deficit in the PS19 mouse model of tauopathy. Front Cell Neurosci 2024; 18:1338502. [PMID: 38638303 PMCID: PMC11024353 DOI: 10.3389/fncel.2024.1338502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 03/18/2024] [Indexed: 04/20/2024] Open
Abstract
Background Accumulation of tau in synapses in the early stages of Alzheimer's disease (AD) has been shown to cause synaptic damage, synaptic loss, and the spread of tau pathology through trans-synaptically connected neurons. Moreover, synaptic loss correlates with a decline in cognitive function, providing an opportunity to investigate therapeutic strategies to target synapses and synaptic tau to rescue or prevent cognitive decline in AD. One of the promising synaptic targets is the 5-HT4 serotonergic receptor present postsynaptically in the brain structures involved in the memory processes. 5-HT4R stimulation exerts synaptogenic and pro-cognitive effects involving synapse-to-nucleus signaling essential for synaptic plasticity. However, it is not known whether 5-HT4R activation has a therapeutic effect on tau pathology. Methods The goal of this study was to investigate the impact of chronic stimulation of 5-HT4R by two agonists, prucalopride and RS-67333, in PS19 mice, a model of tauopathy. We utilized gradient assays to isolate pre- and post-synaptic compartments, followed by biochemical analyses for tau species and ubiquitinated proteins in the synaptic compartments and total brain tissue. Next, we performed kinetic assays to test the proteasome's hydrolysis capacity in treatment conditions. Moreover, behavioral tests such as the open field and non-maternal nest-building tests were used to evaluate anxiety-like behaviors and hippocampal-related cognitive functioning in the treatment paradigm. Results Our results show that 5-HT4R agonism reduced tauopathy, reduced synaptic tau, increased proteasome activity, and improved cognitive functioning in PS19 mice. Our data suggest that enhanced proteasome activity by synaptic mediated signaling leads to the enhanced turnover of tau initially within synapses where the receptors are localized, and over time, the treatment attenuated the accumulation of tau aggregation and improved cognitive functioning of the PS19 mice. Conclusion Therefore, stimulation of 5-HT4R offers a promising therapy to rescue synapses from the accumulation of toxic synaptic tau, evident in the early stages of AD.
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Affiliation(s)
- Shan Jiang
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University Irving Medical Center, New York, NY, United States
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
| | - Eric J. Sydney
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University Irving Medical Center, New York, NY, United States
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
| | - Avery M. Runyan
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University Irving Medical Center, New York, NY, United States
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
| | - Rossana Serpe
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University Irving Medical Center, New York, NY, United States
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
| | - Malavika Srikanth
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University Irving Medical Center, New York, NY, United States
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
| | - Helen Y. Figueroa
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University Irving Medical Center, New York, NY, United States
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
| | - Mu Yang
- The Institute for Genomic Medicine and Psychiatry, Columbia University Irving Medical Center, New York, NY, United States
| | - Natura Myeku
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University Irving Medical Center, New York, NY, United States
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
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Khan N, Uribe Isaza J, Rouhi N, Jamani NF, Jabeen S, Gill AK, Tsutsui M, Visser F, Sargin D. Behavioral and Neurophysiological Implications of Pathological Human Tau Expression in Serotonin Neurons. ACS Chem Neurosci 2024; 15:932-943. [PMID: 38377680 PMCID: PMC10921395 DOI: 10.1021/acschemneuro.3c00626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 01/30/2024] [Accepted: 01/31/2024] [Indexed: 02/22/2024] Open
Abstract
Alzheimer's disease (AD) is a progressive degenerative disorder that results in a severe loss of brain cells and irreversible cognitive decline. Memory problems are the most recognized symptoms of AD. However, approximately 90% of patients diagnosed with AD suffer from behavioral symptoms, including mood changes and social impairment years before cognitive dysfunction. Recent evidence indicates that the dorsal raphe nucleus (DRN) is among the initial regions that show tau pathology, which is a hallmark feature of AD. The DRN harbors serotonin (5-HT) neurons, which are critically involved in mood, social, and cognitive regulation. Serotonergic impairment early in the disease process may contribute to behavioral symptoms in AD. However, the mechanisms underlying vulnerability and contribution of the 5-HT system to AD progression remain unknown. Here, we performed behavioral and electrophysiological characterizations in mice expressing a phosphorylation-prone form of human tau (hTauP301L) in 5-HT neurons. We found that pathological tau expression in 5-HT neurons induces anxiety-like behavior and alterations in stress-coping strategies in female and male mice. Female mice also exhibited social disinhibition and mild cognitive impairment in response to 5-HT neuron-specific hTauP301L expression. Behavioral alterations were accompanied by disrupted 5-HT neuron physiology in female and male hTauP301L expressing mice with exacerbated excitability disruption in females only. These data provide mechanistic insights into the brain systems and symptoms impaired early in AD progression, which is critical for disease intervention.
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Affiliation(s)
- Nazmus
S. Khan
- Department
of Psychology, Department of Physiology and Pharmacology, Cumming School of
Medicine, Hotchkiss Brain Institute, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Juan Uribe Isaza
- Department
of Psychology, Department of Physiology and Pharmacology, Cumming School of
Medicine, Hotchkiss Brain Institute, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Nahid Rouhi
- Department
of Psychology, Department of Physiology and Pharmacology, Cumming School of
Medicine, Hotchkiss Brain Institute, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Naila F. Jamani
- Department
of Psychology, Department of Physiology and Pharmacology, Cumming School of
Medicine, Hotchkiss Brain Institute, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Shaista Jabeen
- Department
of Psychology, Department of Physiology and Pharmacology, Cumming School of
Medicine, Hotchkiss Brain Institute, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Amisha K. Gill
- Department
of Psychology, Department of Physiology and Pharmacology, Cumming School of
Medicine, Hotchkiss Brain Institute, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Mio Tsutsui
- Department
of Psychology, Department of Physiology and Pharmacology, Cumming School of
Medicine, Hotchkiss Brain Institute, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Frank Visser
- Department
of Psychology, Department of Physiology and Pharmacology, Cumming School of
Medicine, Hotchkiss Brain Institute, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Derya Sargin
- Department
of Psychology, Department of Physiology and Pharmacology, Cumming School of
Medicine, Hotchkiss Brain Institute, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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Benskey MJ, Panoushek S, Saito T, Saido TC, Grabinski T, Kanaan NM. Behavioral and neuropathological characterization over the adult lifespan of the human tau knock-in mouse. Front Aging Neurosci 2023; 15:1265151. [PMID: 37842124 PMCID: PMC10576558 DOI: 10.3389/fnagi.2023.1265151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 09/11/2023] [Indexed: 10/17/2023] Open
Abstract
Tau is a microtubule-associated protein with a diverse functional repertoire linked to neurodegenerative disease. Recently, a human tau knock-in (MAPT KI) mouse was developed that may overcome many limitations associated with current animal models used to study tau. In MAPT KI mice, the entire murine Mapt gene was replaced with the human MAPT gene under control of the endogenous Mapt promoter. This model represents an ideal in vivo platform to study the function and dysfunction of human tau protein. Accordingly, a detailed understanding of the effects MAPT KI has on structure and function of the CNS is warranted. Here, we provide a detailed behavioral and neuropathological assessment of MAPT KI mice. We compared MAPT KI to wild-type (WT) C57BL/6j mice in behavioral assessments of anxiety, attention, working memory, spatial memory, and motor performance from 6 to 24 months (m) of age. Using immunohistological and biochemical assays, we quantified markers of glia (microglia, astrocytes and oligodendrocytes), synaptic integrity, neuronal integrity and the cytoskeleton. Finally, we quantified levels of total tau, tau isoforms, tau phosphorylation, and tau conformations. MAPT KI mice show normal cognitive and locomotor behavior at all ages, and resilience to mild age-associated locomotor deficits observed in WT mice. Markers of neuronal and synaptic integrity are unchanged in MAPT KI mice with advancing age. Glial markers are largely unchanged in MAPT KI mice, but glial fibrillary acidic protein is increased in the hippocampus of WT and MAPT KI mice at 24 m. MAPT KI mice express all 6 human tau isoforms and levels of tau remain stable throughout adulthood. Hippocampal tau in MAPT KI and WT mice is phosphorylated at serine 396/404 (PHF1) and murine tau in WT animals displays more PHF1 phosphorylation at 6 and 12 m. Lastly, we extended previous reports showing that MAPT KI mice do not display overt pathology. No evidence of other tau phosphorylation residues (AT8, pS422) or abnormal conformations (TNT2 or TOC1) associated with pathogenic tau were detected. The lack of overt pathological changes in MAPT KI mice make this an ideal platform for future investigations into the function and dysfunction of tau protein in vivo.
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Affiliation(s)
- Matthew J. Benskey
- Department of Translational Neuroscience, College of Human Medicine, Michigan State University, Grand Rapids, MI, United States
| | - Spencer Panoushek
- Department of Translational Neuroscience, College of Human Medicine, Michigan State University, Grand Rapids, MI, United States
| | - Takashi Saito
- Department of Neurocognitive Science, Institute of Brain Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
- Laboratory for Proteolytic Neuroscience, Riken Center for Brain Science, Wako, Japan
| | - Takaomi C. Saido
- Laboratory for Proteolytic Neuroscience, Riken Center for Brain Science, Wako, Japan
| | - Tessa Grabinski
- Department of Translational Neuroscience, College of Human Medicine, Michigan State University, Grand Rapids, MI, United States
| | - Nicholas M. Kanaan
- Department of Translational Neuroscience, College of Human Medicine, Michigan State University, Grand Rapids, MI, United States
- Neuroscience Program, Michigan State University, East Lansing, MI, United States
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Sonsalla MM, Lamming DW. Geroprotective interventions in the 3xTg mouse model of Alzheimer's disease. GeroScience 2023:10.1007/s11357-023-00782-w. [PMID: 37022634 PMCID: PMC10400530 DOI: 10.1007/s11357-023-00782-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 03/23/2023] [Indexed: 04/07/2023] Open
Abstract
Alzheimer's disease (AD) is an age-associated neurodegenerative disease. As the population ages, the increasing prevalence of AD threatens massive healthcare costs in the coming decades. Unfortunately, traditional drug development efforts for AD have proven largely unsuccessful. A geroscience approach to AD suggests that since aging is the main driver of AD, targeting aging itself may be an effective way to prevent or treat AD. Here, we discuss the effectiveness of geroprotective interventions on AD pathology and cognition in the widely utilized triple-transgenic mouse model of AD (3xTg-AD) which develops both β-amyloid and tau pathologies characteristic of human AD, as well as cognitive deficits. We discuss the beneficial impacts of calorie restriction (CR), the gold standard for geroprotective interventions, and the effects of other dietary interventions including protein restriction. We also discuss the promising preclinical results of geroprotective pharmaceuticals, including rapamycin and medications for type 2 diabetes. Though these interventions and treatments have beneficial effects in the 3xTg-AD model, there is no guarantee that they will be as effective in humans, and we discuss the need to examine these interventions in additional animal models as well as the urgent need to test if some of these approaches can be translated from the lab to the bedside for the treatment of humans with AD.
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Affiliation(s)
- Michelle M Sonsalla
- Department of Medicine, University of Wisconsin-Madison, 2500 Overlook Terrace, VAH C3127 Research 151, Madison, WI, 53705, USA
- William S. Middleton Memorial Veterans Hospital, Madison, WI, 53705, USA
- Comparative Biomedical Sciences Graduate Program, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Dudley W Lamming
- Department of Medicine, University of Wisconsin-Madison, 2500 Overlook Terrace, VAH C3127 Research 151, Madison, WI, 53705, USA.
- William S. Middleton Memorial Veterans Hospital, Madison, WI, 53705, USA.
- Comparative Biomedical Sciences Graduate Program, University of Wisconsin-Madison, Madison, WI, 53706, USA.
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Jiang S, Sydney EJ, Runyan AM, Serpe R, Figueroa HY, Yang M, Myeku N. 5-HT4 receptor agonists treatment reduces tau pathology and behavioral deficit in the PS19 mouse model of tauopathy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.03.526871. [PMID: 36778352 PMCID: PMC9915615 DOI: 10.1101/2023.02.03.526871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Accumulation of tau in synapses in Alzheimer’s disease (AD) has been shown to cause synaptic damage, synaptic loss, and the spread of pathology through synaptically connected neurons. Synaptic loss correlates with a decline in cognition, providing an opportunity to investigate strategies to target synaptic tau to rescue or prevent cognitive decline. One of the promising synaptic targets is the 5-HT4 receptor present post-synaptically in the brain areas involved in the memory processes. 5-HT4R activation exerts synaptogenic and pro-cognitive effects involving synapse-to-nucleus signaling essential for synaptic plasticity. However, it is not known whether 5-HT4R activation has a therapeutic effect on tauopathy. The goal of this study was to investigate the impact of stimulation of 5-HT4R in tauopathy mice. Our results show that 5-HT4R agonism led to reduced tauopathy and synaptic tau and correlated with increased proteasome activity and improved cognitive functioning in PS19 mice. Thus, stimulation of 5-HT4R offers a promising therapy to rescue synapses from toxic synaptic tau.
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Cho JD, Yang M, Santa-Maria I. Modeling Alzheimer's disease: considerations for a better translational and replicable mouse model. Neural Regen Res 2022; 17:2448-2449. [PMID: 35535894 PMCID: PMC9120700 DOI: 10.4103/1673-5374.335787] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/01/2021] [Accepted: 09/08/2021] [Indexed: 12/01/2022] Open
Affiliation(s)
- Joshua D. Cho
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Department of Pathology & Cell Biology, Columbia University, New York, NY, USA
| | - Mu Yang
- The Mouse NeuroBehavior Core. Institute for Genomic Medicine, Columbia University, New York, NY, USA
| | - Ismael Santa-Maria
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Department of Pathology & Cell Biology, Columbia University, New York, NY, USA
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Disruption of tubulin-alpha4a polyglutamylation prevents aggregation of hyper-phosphorylated tau and microglia activation in mice. Nat Commun 2022; 13:4192. [PMID: 35858909 PMCID: PMC9300677 DOI: 10.1038/s41467-022-31776-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 06/30/2022] [Indexed: 11/14/2022] Open
Abstract
Dissociation of hyper-phosphorylated Tau from neuronal microtubules and its pathological aggregates, are hallmarks in the etiology of tauopathies. The Tau-microtubule interface is subject to polyglutamylation, a reversible posttranslational modification, increasing negative charge at tubulin C-terminal tails. Here, we asked whether tubulin polyglutamylation may contribute to Tau pathology in vivo. Since polyglutamylases modify various proteins other than tubulin, we generated a knock-in mouse carrying gene mutations to abolish Tuba4a polyglutamylation in a substrate-specific manner. We found that Tuba4a lacking C-terminal polyglutamylation prevents the binding of Tau and GSK3 kinase to neuronal microtubules, thereby strongly reducing phospho-Tau levels. Notably, crossbreeding of the Tuba4a knock-in mouse with the hTau tauopathy model, expressing a human Tau transgene, reversed hyper-phosphorylation and oligomerization of Tau and normalized microglia activation in brain. Our data highlight tubulin polyglutamylation as a potential therapeutic strategy in fighting tauopathies. Pathologic oligomerization of hyper-phosphorylated Tau is a hallmark of tauopathies. Here the authors show that the loss of tubulin a4 polyglutamylation reverses tau hyperphosphorylation, oligomerization and microglia activation in a tauopathy mouse.
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Trease AJ, George JW, Roland NJ, Lichter EZ, Emanuel K, Totusek S, Fox HS, Stauch KL. Hyperphosphorylated Human Tau Accumulates at the Synapse, Localizing on Synaptic Mitochondrial Outer Membranes and Disrupting Respiration in a Mouse Model of Tauopathy. Front Mol Neurosci 2022; 15:852368. [PMID: 35359570 PMCID: PMC8960727 DOI: 10.3389/fnmol.2022.852368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 01/31/2022] [Indexed: 12/24/2022] Open
Abstract
Neurogenerative disorders, such as Alzheimer’s disease (AD), represent a growing public health challenge in aging societies. Tauopathies, a subset of neurodegenerative disorders that includes AD, are characterized by accumulation of fibrillar and hyperphosphorylated forms of microtubule-associated protein tau with coincident mitochondrial abnormalities and neuronal dysfunction. Although, in vitro, tau impairs axonal transport altering mitochondrial distribution, clear in vivo mechanisms associating tau and mitochondrial dysfunction remain obscure. Herein, we investigated the effects of human tau on brain mitochondria in vivo using transgenic htau mice at ages preceding and coinciding with onset of tauopathy. Subcellular proteomics combined with bioenergetic assessment revealed pathologic forms of tau preferentially associate with synaptic over non-synaptic mitochondria coinciding with changes in bioenergetics, reminiscent of an aged synaptic mitochondrial phenotype in wild-type mice. While mitochondrial content was unaltered, mitochondrial maximal respiration was impaired in synaptosomes from htau mice. Further, mitochondria-associated tau was determined to be outer membrane-associated using the trypsin protection assay and carbonate extraction. These findings reveal non-mutant human tau accumulation at the synapse has deleterious effects on mitochondria, which likely contributes to synaptic dysfunction observed in the context of tauopathy.
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