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Cranston AL, Kraev I, Stewart MG, Horsley D, Santos RX, Robinson L, Dreesen E, Armstrong P, Palliyil S, Harrington CR, Wischik CM, Riedel G. Rescue of synaptosomal glutamate release defects in tau transgenic mice by the tau aggregation inhibitor hydromethylthionine. Cell Signal 2024; 121:111269. [PMID: 38909930 DOI: 10.1016/j.cellsig.2024.111269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 06/13/2024] [Accepted: 06/20/2024] [Indexed: 06/25/2024]
Abstract
Glutamatergic neurotransmission, important for learning and memory, is disrupted in different ways in patients with Alzheimer's disease (AD) and frontotemporal dementia (FTD) tauopathies. We have previously reported that two tau transgenic mouse models, L1 and L66, produce different phenotypes resembling AD and FTD, respectively. The AD-like L1 model expresses the truncated core aggregation domain of the AD paired helical filament (PHF) form of tau (tau296-390) whereas the FTD-like L66 model expresses full-length tau carrying two mutations at P301S/G335D. We have used synaptosomes isolated from these mice to investigate K+-evoked glutamate release and, if abnormal, to determine responsiveness to hydromethylthionine, a tau aggregation inhibitor previously shown to reduce tau pathology in these models. We report that the transgenes in these two mouse lines cause opposite abnormalities in glutamate release. Over-expression of the core tau unit in L1 produces a significant reduction in glutamate release and a loss of Ca2+-dependency compared with wild-type control mice. Full-length mutant tau produces an increase in glutamate release that retains normal Ca2+-dependency. Chronic pre-treatment with hydromethylthionine normalises both reduced (L1) and excessive glutamate (L66) and restores normal Ca2+-dependency in L1 mice. This implies that both patterns of impairment are the result of tau aggregation, but that the direction and Ca2+-dependency of the abnormality is determined by expression of the disease-specific transgene. Our results lead to the conclusion that the tauopathies need not be considered a single entity in terms of the downstream effects of pathological aggregation of tau protein. In this case, directionally opposite abnormalities in glutamate release resulting from different types of tau aggregation in the two mouse models can be corrected by hydromethylthionine. This may help to explain the activity of hydromethylthionine on cognitive decline and brain atrophy in both AD and behavioural-variant FTD.
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Affiliation(s)
- Anna L Cranston
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill AB25 2ZD, UK
| | - Igor Kraev
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes MK7 6AA, UK
| | - Mike G Stewart
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes MK7 6AA, UK
| | - David Horsley
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill AB25 2ZD, UK
| | - Renato X Santos
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill AB25 2ZD, UK
| | - Lianne Robinson
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill AB25 2ZD, UK
| | - Eline Dreesen
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill AB25 2ZD, UK
| | - Paul Armstrong
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill AB25 2ZD, UK
| | - Soumya Palliyil
- Scottish Biologics Facility, University of Aberdeen, Foresterhill AB25 2ZP, UK
| | - Charles R Harrington
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill AB25 2ZD, UK; TauRx Therapeutics Ltd, 395 King Street, Aberdeen, AB24 5RP, UK
| | - Claude M Wischik
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill AB25 2ZD, UK; TauRx Therapeutics Ltd, 395 King Street, Aberdeen, AB24 5RP, UK
| | - Gernot Riedel
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill AB25 2ZD, UK.
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2
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Pierson SR, Fiock KL, Wang R, Balasubramanian N, Reinhardt J, Khan KM, James TD, Hunter ML, Cooper BJ, Williamsen HR, Betters R, Deniz K, Lee G, Aldridge G, Hefti MM, Marcinkiewcz CA. Tau pathology in the dorsal raphe may be a prodromal indicator of Alzheimer's disease. Mol Psychiatry 2024:10.1038/s41380-024-02664-9. [PMID: 39143322 DOI: 10.1038/s41380-024-02664-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 06/22/2024] [Accepted: 07/04/2024] [Indexed: 08/16/2024]
Abstract
Protein aggregation in brainstem nuclei is thought to occur in the early stages of Alzheimer's disease (AD), but its specific role in driving prodromal symptoms and disease progression is largely unknown. The dorsal raphe nucleus (DRN) contains a large population of serotonin (5-hydroxytryptamine; 5-HT) neurons that regulate mood, reward-related behavior, and sleep, which are all disrupted in AD. We report here that tau pathology is present in the DRN of individuals 25-80 years old without a known history of dementia, and its prevalence was comparable to the locus coeruleus (LC). By comparison, fewer cases were positive for other pathological proteins including α-synuclein, β-amyloid, and TDP-43. To evaluate how early tau pathology impacts behavior, we overexpressed human P301L-tau in the DRN of mice and observed depressive-like behaviors and hyperactivity without deficits in spatial memory. Tau pathology was predominantly found in neurons relative to glia and colocalized with a significant proportion of Tph2-expressing neurons in the DRN. 5-HT neurons were also hyperexcitable in P301L-tauDRN mice, and there was an increase in the amplitude of excitatory post-synaptic currents (EPSCs). Moreover, astrocytic density was elevated in the DRN and accompanied by an increase in IL-1α and Frk expression, which suggests increased inflammatory signaling. Additionally, tau pathology was detected in axonal processes in the thalamus, hypothalamus, amygdala, and caudate putamen. A significant proportion of this tau pathology colocalized with the serotonin reuptake transporter (SERT), suggesting that tau may spread in an anterograde manner to regions outside the DRN. Together these results indicate that tau pathology accumulates in the DRN in a subset of individuals over 50 years and may lead to behavioral dysregulation, 5-HT neuronal dysfunction, and activation of local astrocytes which may be prodromal indicators of AD.
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Affiliation(s)
- Samantha R Pierson
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA, 52242, USA
| | - Kimberly L Fiock
- Department of Pathology, University of Iowa, Iowa City, IA, 52242, USA
| | - Ruixiang Wang
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA, 52242, USA
| | | | - Jessica Reinhardt
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA, 52242, USA
| | - Kanza M Khan
- Psychological Sciences Department, Daemen University, Amherst, NY, 14226, USA
| | - Thomas D James
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA, 52242, USA
| | - Mikayla L Hunter
- Department of Pathology, University of Iowa, Iowa City, IA, 52242, USA
| | - Benjamin J Cooper
- Department of Pathology, University of Iowa, Iowa City, IA, 52242, USA
| | | | - Ryan Betters
- Department of Pathology, University of Iowa, Iowa City, IA, 52242, USA
| | - Kaancan Deniz
- Department of Neurology, University of Iowa, Iowa City, IA, 52242, USA
| | - Gloria Lee
- Department of Internal Medicine, University of Iowa, Iowa City, IA, 52242, USA
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, 52242, USA
| | - Georgina Aldridge
- Department of Neurology, University of Iowa, Iowa City, IA, 52242, USA
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, 52242, USA
| | - Marco M Hefti
- Department of Pathology, University of Iowa, Iowa City, IA, 52242, USA
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, 52242, USA
| | - Catherine A Marcinkiewcz
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA, 52242, USA.
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, 52242, USA.
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3
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Ortiz C, Pearson A, McCartan R, Roche S, Carothers N, Browning M, Perez S, He B, Ginsberg SD, Mullan M, Mufson EJ, Crawford F, Ojo J. Overexpression of pathogenic tau in astrocytes causes a reduction in AQP4 and GLT1, an immunosuppressed phenotype and unique transcriptional responses to repetitive mild TBI without appreciable changes in tauopathy. J Neuroinflammation 2024; 21:130. [PMID: 38750510 PMCID: PMC11096096 DOI: 10.1186/s12974-024-03117-4] [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: 02/22/2024] [Accepted: 04/30/2024] [Indexed: 05/18/2024] Open
Abstract
Epidemiological studies have unveiled a robust link between exposure to repetitive mild traumatic brain injury (r-mTBI) and elevated susceptibility to develop neurodegenerative disorders, notably chronic traumatic encephalopathy (CTE). The pathogenic lesion in CTE cases is characterized by the accumulation of hyperphosphorylated tau in neurons around small cerebral blood vessels which can be accompanied by astrocytes that contain phosphorylated tau, the latter termed tau astrogliopathy. However, the contribution of tau astrogliopathy to the pathobiology and functional consequences of r-mTBI/CTE or whether it is merely a consequence of aging remains unclear. We addressed these pivotal questions by utilizing a mouse model harboring tau-bearing astrocytes, GFAPP301L mice, subjected to our r-mTBI paradigm. Despite the fact that r-mTBI did not exacerbate tau astrogliopathy or general tauopathy, it increased phosphorylated tau in the area underneath the impact site. Additionally, gene ontology analysis of tau-bearing astrocytes following r-mTBI revealed profound alterations in key biological processes including immunological and mitochondrial bioenergetics. Moreover, gene array analysis of microdissected astrocytes accrued from stage IV CTE human brains revealed an immunosuppressed astroglial phenotype similar to tau-bearing astrocytes in the GFAPP301L model. Additionally, hippocampal reduction of proteins involved in water transport (AQP4) and glutamate homeostasis (GLT1) was found in the mouse model of tau astrogliopathy. Collectively, these findings reveal the importance of understanding tau astrogliopathy and its role in astroglial pathobiology under normal circumstances and following r-mTBI. The identified mechanisms using this GFAPP301L model may suggest targets for therapeutic interventions in r-mTBI pathogenesis in the context of CTE.
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Affiliation(s)
- Camila Ortiz
- The Roskamp Institute, Sarasota, FL, USA.
- The Open University, Milton Keynes, UK.
| | - Andrew Pearson
- The Roskamp Institute, Sarasota, FL, USA
- The Open University, Milton Keynes, UK
| | | | | | | | | | | | - Bin He
- Barrow Neurological Institute, Phoenix, AZ, USA
| | - Stephen D Ginsberg
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY, USA
- Departments of Psychiatry, Neuroscience and Physiology, and NYU Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA
| | | | | | - Fiona Crawford
- The Roskamp Institute, Sarasota, FL, USA
- The Open University, Milton Keynes, UK
- James A. Haley Veterans Hospital, Tampa, FL, USA
| | - Joseph Ojo
- The Roskamp Institute, Sarasota, FL, USA
- The Open University, Milton Keynes, UK
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4
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Hartnell IJ, Woodhouse D, Jasper W, Mason L, Marwaha P, Graffeuil M, Lau LC, Norman JL, Chatelet DS, Buee L, Nicoll JAR, Blum D, Dorothee G, Boche D. Glial reactivity and T cell infiltration in frontotemporal lobar degeneration with tau pathology. Brain 2024; 147:590-606. [PMID: 37703311 PMCID: PMC10834257 DOI: 10.1093/brain/awad309] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 07/23/2023] [Accepted: 08/11/2023] [Indexed: 09/15/2023] Open
Abstract
Frontotemporal lobar degeneration with tau (FTLD-tau) is a group of tauopathies that underlie ∼50% of FTLD cases. Identification of genetic risk variants related to innate/adaptive immunity have highlighted a role for neuroinflammation and neuroimmune interactions in FTLD. Studies have shown microglial and astrocyte activation together with T cell infiltration in the brain of THY-Tau22 tauopathy mice. However, this remains to be confirmed in FTLD-tau patients. We conducted a detailed post-mortem study of FTLD-tau cases including 45 progressive supranuclear palsy with clinical frontotemporal dementia, 33 Pick's disease, 12 FTLD-MAPT and 52 control brains to characterize the link between phosphorylated tau (pTau) epitopes and the innate and adaptive immunity. Tau pathology was assessed in the cerebral cortex using antibodies directed against: Tau-2 (phosphorylated and unphosphorylated tau), AT8 (pSer202/pThr205), AT100 (pThr212/pSer214), CP13 (pSer202), PHF1 (pSer396/pSer404), pThr181 and pSer356. The immunophenotypes of microglia and astrocytes were assessed with phenotypic markers (Iba1, CD68, HLA-DR, CD64, CD32a, CD16 for microglia and GFAP, EAAT2, glutamine synthetase and ALDH1L1 for astrocytes). The adaptive immune response was explored via CD4+ and CD8+ T cell quantification and the neuroinflammatory environment was investigated via the expression of 30 inflammatory-related proteins using V-Plex Meso Scale Discovery. As expected, all pTau markers were increased in FTLD-tau cases compared to controls. pSer356 expression was greatest in FTLD-MAPT cases versus controls (P < 0.0001), whereas the expression of other markers was highest in Pick's disease. Progressive supranuclear palsy with frontotemporal dementia consistently had a lower pTau protein load compared to Pick's disease across tau epitopes. The only microglial marker increased in FTLD-tau was CD16 (P = 0.0292) and specifically in FTLD-MAPT cases (P = 0.0150). However, several associations were detected between pTau epitopes and microglia, supporting an interplay between them. GFAP expression was increased in FTLD-tau (P = 0.0345) with the highest expression in Pick's disease (P = 0.0019), while ALDH1L1 was unchanged. Markers of astrocyte glutamate cycling function were reduced in FTLD-tau (P = 0.0075; Pick's disease: P < 0.0400) implying astrocyte reactivity associated with a decreased glutamate cycling activity, which was further associated with pTau expression. Of the inflammatory proteins assessed in the brain, five chemokines were upregulated in Pick's disease cases (P < 0.0400), consistent with the recruitment of CD4+ (P = 0.0109) and CD8+ (P = 0.0014) T cells. Of note, the CD8+ T cell infiltration was associated with pTau epitopes and microglial and astrocytic markers. Our results highlight that FTLD-tau is associated with astrocyte reactivity, remarkably little activation of microglia, but involvement of adaptive immunity in the form of chemokine-driven recruitment of T lymphocytes.
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Affiliation(s)
- Iain J Hartnell
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
| | - Declan Woodhouse
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
| | - William Jasper
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
| | - Luke Mason
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
| | - Pavan Marwaha
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
| | - Manon Graffeuil
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
| | - Laurie C Lau
- Clinical and Experimental Sciences, Faculty of Medicine, Sir Henry Wellcome Laboratories, University of Southampton, Southampton O16 6YD, UK
| | - Jeanette L Norman
- Histochemistry Research Unit, Clinical and Experimental Sciences, Faculty of Medicine University of Southampton, Southampton SO16 6YD, UK
| | - David S Chatelet
- Biomedical Imaging Unit, University Hospital Southampton NHS Trust, Southampton SO16 6YD, UK
| | - Luc Buee
- University of Lille, Inserm, CHU Lille, UMR-S1172—Lille Neurosciences and Cognition, Lille 59045, France
- Alzheimer and Tauopathies, LabEX DISTALZ, Lille 59000, France
| | - James A R Nicoll
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
- Department of Cellular Pathology, University Hospital Southampton NHS Trust, Southampton SO16 6YD, UK
| | - David Blum
- University of Lille, Inserm, CHU Lille, UMR-S1172—Lille Neurosciences and Cognition, Lille 59045, France
- Alzheimer and Tauopathies, LabEX DISTALZ, Lille 59000, France
| | - Guillaume Dorothee
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
- Sorbonne Université, Inserm, Centre de Recherche Saint-Antoine, CRSA, Immune System and Neuroinflammation Laboratory, Hôpital Saint-Antoine, Paris 75012, France
| | - Delphine Boche
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
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5
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Eisenbaum M, Pearson A, Ortiz C, Mullan M, Crawford F, Ojo J, Bachmeier C. ApoE4 expression disrupts tau uptake, trafficking, and clearance in astrocytes. Glia 2024; 72:184-205. [PMID: 37668005 DOI: 10.1002/glia.24469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 08/07/2023] [Accepted: 08/26/2023] [Indexed: 09/06/2023]
Abstract
Tauopathies are a collection of neurodegenerative diseases characterized by the accumulation of pathogenic aggregates of the microtubule-associated protein tau. Despite the prevalence and diversity of tau astrogliopathy in tauopathies, the interactions between astrocytes and tau in the brain, and the influence of neurodegenerative genetic risk factors like the apolipoprotein E4 (apoE4) isoform, are largely unknown. Here, we leveraged primary and immortalized astrocytes expressing humanized apoE isoforms to characterize the mechanisms by which astrocytes interact with and eliminate extracellular tau, and the influence of apoE genotype on these processes. Our work indicates that astrocytes rapidly internalize, process, and release tau via an exosomal secretory mechanism under physiological conditions. However, we found that apoE4 disrupted these processes in comparison to apoE3, resulting in an astrocytic phenotype prone to intracellular tau accumulation. Furthermore, exposure to repetitive mild traumatic brain injuries exacerbated the apoE4-induced impairments in tau processing and elimination by astrocytes in apoE4 targeted-replacement mice. The diminished ability of apoE4 astrocytes to eliminate extracellular tau can lead to an accumulation of pathogenic tau, which induces mitochondrial dysfunction, as demonstrated by our studies. In total, our findings suggest that the apoE4 isoform lowers the threshold of astrocytic resilience to pathogenic tau, rendering them susceptible to bioenergetic deficits in the early stages of neurodegenerative diseases such as traumatic brain injury, potentially contributing to neurological decline.
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Affiliation(s)
| | | | | | | | - Fiona Crawford
- The Roskamp Institute, Sarasota, Florida, USA
- James A. Haley Veterans' Hospital, Tampa, Florida, USA
| | - Joseph Ojo
- The Roskamp Institute, Sarasota, Florida, USA
| | - Corbin Bachmeier
- The Roskamp Institute, Sarasota, Florida, USA
- Bay Pines VA Healthcare System, Bay Pines, Florida, USA
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6
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Canet G, Rocaboy E, Diego-Diàz S, Whittington RA, Julien C, Planel E. Methods for Biochemical Isolation of Insoluble Tau in Rodent Models of Tauopathies. Methods Mol Biol 2024; 2754:323-341. [PMID: 38512674 DOI: 10.1007/978-1-0716-3629-9_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
The intracellular accumulation of microtubule-associated protein tau is a characteristic feature of tauopathies, a group of neurodegenerative diseases including Alzheimer's disease. Formation of insoluble tau aggregates is initiated by the abnormal hyperphosphorylation and oligomerization of tau. Over the past decades, multiple transgenic rodent models mimicking tauopathies have been develop, showcasing this neuropathological hallmark. The biochemical analysis of insoluble tau in these models has served as a valuable tool to understand the progression of tau-related pathology. In this chapter, we provide a comprehensive review of the two primary methods for isolating insoluble tau, namely, sarkosyl and formic acid extraction (and their variants), which are employed for biochemical analysis in transgenic mouse models of tauopathy. We also analyze the strengths and limitations of these methods.
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Affiliation(s)
- Geoffrey Canet
- Faculté de Médecine, Département de Psychiatrie et Neurosciences, Université Laval, Quebec, QC, Canada
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Quebec, QC, Canada
| | - Emma Rocaboy
- Faculté de Médecine, Département de Psychiatrie et Neurosciences, Université Laval, Quebec, QC, Canada
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Quebec, QC, Canada
| | - Sofia Diego-Diàz
- Faculté de Médecine, Département de Psychiatrie et Neurosciences, Université Laval, Quebec, QC, Canada
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Quebec, QC, Canada
| | - Robert A Whittington
- Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Carl Julien
- Centre de Recherche en Sciences Animales de Deschambault, Deschambault, QC, Canada
- Faculté des sciences de l'agriculture et de l'alimentation, Université Laval, Quebec, QC, Canada
| | - Emmanuel Planel
- Faculté de Médecine, Département de Psychiatrie et Neurosciences, Université Laval, Quebec, QC, Canada.
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Quebec, QC, Canada.
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7
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Rupareliya VP, Singh AA, Butt AM, A H, Kumar H. The "molecular soldiers" of the CNS: Astrocytes, a comprehensive review on their roles and molecular signatures. Eur J Pharmacol 2023; 959:176048. [PMID: 37758010 DOI: 10.1016/j.ejphar.2023.176048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/24/2023] [Accepted: 09/13/2023] [Indexed: 09/29/2023]
Abstract
For a long time, neurons held the position of central players in the nervous system. Since there are far more astrocytes than neurons in the brain, it makes us wonder if these cells just take up space and support the neurons or if they are actively participating in central nervous system (CNS) homeostasis. Now, astrocytes' contribution to CNS physiology is appreciated as they are known to regulate ion and neurotransmitter levels, synapse formation and elimination, blood-brain barrier integrity, immune function, cerebral blood flow, and many more. In many neurological and psychiatric disorders, astrocyte functions are altered. Advancements in microscopic and transcriptomic tools revealed populations of astrocytes with varied morphology, electrophysiological properties, and transcriptomic profiles. Neuron-circuit-specific functions and neuron-specific interactions of astroglial subpopulations are found, which suggests that diversity is essential in carrying out diverse region-specific CNS functions. Investigations on heterogeneous astrocyte populations are revealing new astrocyte functions and their role in pathological conditions, opening a new therapeutic avenue for targeting neurological conditions. The true extent of astrocytic heterogeneity and its functional implications are yet to be fully explored. This review summarizes essential astrocytic functions and their relevance in pathological conditions and discusses astrocytic diversity in relation to morphology, function, and gene expression throughout the CNS.
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Affiliation(s)
- Vimal P Rupareliya
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Aditya A Singh
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Ayub Mohammed Butt
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Hariharan A
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Hemant Kumar
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat 382355, India.
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8
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Wu M, Chen Z, Jiang M, Bao B, Li D, Yin X, Wang X, Liu D, Zhu LQ. Friend or foe: role of pathological tau in neuronal death. Mol Psychiatry 2023; 28:2215-2227. [PMID: 36918705 DOI: 10.1038/s41380-023-02024-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 02/25/2023] [Accepted: 02/28/2023] [Indexed: 03/16/2023]
Abstract
Neuronal death is one of the most common pathological hallmarks of diverse neurological diseases, which manifest varying degrees of cognitive or motor dysfunction. Neuronal death can be classified into multiple forms with complicated and unique regulatory signaling pathways. Tau is a key microtubule-associated protein that is predominantly expressed in neurons to stabilize microtubules under physiological conditions. In contrast, pathological tau always detaches from microtubules and is implicated in a series of neurological disorders that are characterized by irreversible neuronal death, such as necrosis, apoptosis, necroptosis, pyroptosis, ferroptosis, autophagy-dependent neuronal death and phagocytosis by microglia. However, recent studies have also revealed that pathological tau can facilitate neuron escape from acute apoptosis, delay necroptosis through its action on granulovacuolar degeneration bodies (GVBs), and facilitate iron export from neurons to block ferroptosis. In this review, we briefly describe the current understanding of how pathological tau exerts dual effects on neuronal death by acting as a double-edged sword in different neurological diseases. We propose that elucidating the mechanism by which pathological tau affects neuronal death is critical for exploring novel and precise therapeutic strategies for neurological disorders.
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Affiliation(s)
- Moxin Wu
- Department of Medical Laboratory, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China
| | - Zhiying Chen
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China
- Department of Neurology, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China
| | - Min Jiang
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China
| | - Bing Bao
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China
- Department of Neurology, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China
| | - Dongling Li
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China
- Department of Neurology, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China
| | - Xiaoping Yin
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China.
- Department of Neurology, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China.
| | - Xueren Wang
- Department of Anesthesiology, Shanxi Bethune Hospital, Taiyuan, 030032, China.
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Dan Liu
- Department of Medical Genetics, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Ling-Qiang Zhu
- Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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9
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Fontana IC, Souza DG, Souza DO, Gee A, Zimmer ER, Bongarzone S. A Medicinal Chemistry Perspective on Excitatory Amino Acid Transporter 2 Dysfunction in Neurodegenerative Diseases. J Med Chem 2023; 66:2330-2346. [PMID: 36787643 PMCID: PMC9969404 DOI: 10.1021/acs.jmedchem.2c01572] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
The excitatory amino acid transporter 2 (EAAT2) plays a key role in the clearance and recycling of glutamate - the major excitatory neurotransmitter in the mammalian brain. EAAT2 loss/dysfunction triggers a cascade of neurodegenerative events, comprising glutamatergic excitotoxicity and neuronal death. Nevertheless, our current knowledge regarding EAAT2 in neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) and Alzheimer's disease (AD), is restricted to post-mortem analysis of brain tissue and experimental models. Thus, detecting EAAT2 in the living human brain might be crucial to improve diagnosis/therapy for ALS and AD. This perspective article describes the role of EAAT2 in physio/pathological processes and provides a structure-activity relationship of EAAT2-binders, bringing two perspectives: therapy (activators) and diagnosis (molecular imaging tools).
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Affiliation(s)
- Igor C Fontana
- School of Biomedical Engineering and Imaging Sciences, St Thomas' Hospital, King's College London, London SE1 7EH, United Kingdom.,Graduate Program in Biological Sciences: Biochemistry, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600, 90035-003 Porto Alegre, Brazil.,Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Blickagången 16 - Neo floor seventh, 141 83 Stockholm, Sweden
| | - Débora G Souza
- Graduate Program in Biological Sciences: Biochemistry, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600, 90035-003 Porto Alegre, Brazil.,Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul, Av. Ipiranga, 6681 Porto Alegre, Brazil
| | - Diogo O Souza
- Graduate Program in Biological Sciences: Biochemistry, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600, 90035-003 Porto Alegre, Brazil.,Department of Biochemistry, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600, 90035-003 Porto Alegre, Brazil
| | - Antony Gee
- School of Biomedical Engineering and Imaging Sciences, St Thomas' Hospital, King's College London, London SE1 7EH, United Kingdom
| | - Eduardo R Zimmer
- Department of Biochemistry, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600, 90035-003 Porto Alegre, Brazil.,Department of Pharmacology, Universidade Federal do Rio Grande do Sul, Av. Sarmento Leite 500, sala, 90035-003 Porto Alegre, Brazil.,Graduate Program in Biological Sciences: Biochemistry (PPGBioq), and Pharmacology and Therapeutics (PPGFT), Universidade Federal do Rio Grande do Sul, Av. Sarmento Leite 500, sala, 305 Porto Alegre, Brazil.,Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul, Av. Ipiranga, 6681 Porto Alegre, Brazil.,McGill University Research Centre for Studies in Aging, McGill University, Montreal, Quebec H4H 1R3, Canada
| | - Salvatore Bongarzone
- School of Biomedical Engineering and Imaging Sciences, St Thomas' Hospital, King's College London, London SE1 7EH, United Kingdom
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10
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Lee D, Lee VMY, Hur SK. Manipulation of the diet-microbiota-brain axis in Alzheimer's disease. Front Neurosci 2022; 16:1042865. [PMID: 36408394 PMCID: PMC9672822 DOI: 10.3389/fnins.2022.1042865] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 10/14/2022] [Indexed: 11/06/2022] Open
Abstract
Several studies investigating the pathogenesis of Alzheimer's disease have identified various interdependent constituents contributing to the exacerbation of the disease, including Aβ plaque formation, tau protein hyperphosphorylation, neurofibrillary tangle accumulation, glial inflammation, and the eventual loss of proper neural plasticity. Recently, using various models and human patients, another key factor has been established as an influential determinant in brain homeostasis: the gut-brain axis. The implications of a rapidly aging population and the absence of a definitive cure for Alzheimer's disease have prompted a search for non-pharmaceutical tools, of which gut-modulatory therapies targeting the gut-brain axis have shown promise. Yet multiple recent studies examining changes in human gut flora in response to various probiotics and environmental factors are limited and difficult to generalize; whether the state of the gut microbiota in Alzheimer's disease is a cause of the disease, a result of the disease, or both through numerous feedback loops in the gut-brain axis, remains unclear. However, preliminary findings of longitudinal studies conducted over the past decades have highlighted dietary interventions, especially Mediterranean diets, as preventative measures for Alzheimer's disease by reversing neuroinflammation, modifying the intestinal and blood-brain barrier (BBB), and addressing gut dysbiosis. Conversely, the consumption of Western diets intensifies the progression of Alzheimer's disease through genetic alterations, impaired barrier function, and chronic inflammation. This review aims to support the growing body of experimental and clinical data highlighting specific probiotic strains and particular dietary components in preventing Alzheimer's disease via the gut-brain axis.
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Affiliation(s)
- Daniel Lee
- Middleton High School, Middleton, WI, United States
| | - Virginia M-Y. Lee
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurodegenerative Disease Research, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
| | - Seong Kwon Hur
- Center for Neurodegenerative Disease Research, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
- Department of Neuroscience, Genentech, Inc., South San Francisco, CA, United States
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11
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Andersen JV, Schousboe A, Verkhratsky A. Astrocyte energy and neurotransmitter metabolism in Alzheimer's disease: integration of the glutamate/GABA-glutamine cycle. Prog Neurobiol 2022; 217:102331. [PMID: 35872221 DOI: 10.1016/j.pneurobio.2022.102331] [Citation(s) in RCA: 73] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 07/14/2022] [Accepted: 07/19/2022] [Indexed: 02/06/2023]
Abstract
Astrocytes contribute to the complex cellular pathology of Alzheimer's disease (AD). Neurons and astrocytes function in close collaboration through neurotransmitter recycling, collectively known as the glutamate/GABA-glutamine cycle, which is essential to sustain neurotransmission. Neurotransmitter recycling is intimately linked to astrocyte energy metabolism. In the course of AD, astrocytes undergo extensive metabolic remodeling, which may profoundly affect the glutamate/GABA-glutamine cycle. The consequences of altered astrocyte function and metabolism in relation to neurotransmitter recycling are yet to be comprehended. Metabolic alterations of astrocytes in AD deprive neurons of metabolic support, thereby contributing to synaptic dysfunction and neurodegeneration. In addition, several astrocyte-specific components of the glutamate/GABA-glutamine cycle, including glutamine synthesis and synaptic neurotransmitter uptake, are perturbed in AD. Integration of the complex astrocyte biology within the context of AD is essential for understanding the fundamental mechanisms of the disease, while restoring astrocyte metabolism may serve as an approach to arrest or even revert clinical progression of AD.
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Affiliation(s)
- Jens V Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK; Achucarro Center for Neuroscience, IKERBASQUE, 48011 Bilbao, Spain; Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102 Vilnius, Lithuania.
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12
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Involvement of astrocyte senescence in Alzheimer's disease. Curr Opin Neurobiol 2022; 76:102594. [PMID: 35779313 DOI: 10.1016/j.conb.2022.102594] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 05/17/2022] [Accepted: 05/29/2022] [Indexed: 01/10/2023]
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13
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Garrett LR, Niccoli T. Frontotemporal Dementia and Glucose Metabolism. Front Neurosci 2022; 16:812222. [PMID: 35281504 PMCID: PMC8906510 DOI: 10.3389/fnins.2022.812222] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 01/18/2022] [Indexed: 12/02/2022] Open
Abstract
Frontotemporal dementia (FTD), hallmarked by antero-temporal degeneration in the human brain, is the second most common early onset dementia. FTD is a diverse disease with three main clinical presentations, four different identified proteinopathies and many disease-associated genes. The exact pathophysiology of FTD remains to be elucidated. One common characteristic all forms of FTD share is the dysregulation of glucose metabolism in patients’ brains. The brain consumes around 20% of the body’s energy supply and predominantly utilizes glucose as a fuel. Glucose metabolism dysregulation could therefore be extremely detrimental for neuronal health. Research into the association between glucose metabolism and dementias has recently gained interest in Alzheimer’s disease. FTD also presents with glucose metabolism dysregulation, however, this remains largely an unexplored area. A better understanding of the link between FTD and glucose metabolism may yield further insight into FTD pathophysiology and aid the development of novel therapeutics. Here we review our current understanding of FTD and glucose metabolism in the brain and discuss the evidence of impaired glucose metabolism in FTD. Lastly, we review research potentially suggesting a causal relationship between FTD proteinopathies and impaired glucose metabolism in FTD.
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14
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Ezerskiy LA, Schoch KM, Sato C, Beltcheva M, Horie K, Rigo F, Martynowicz R, Karch CM, Bateman RJ, Miller TM. Astrocytic 4R tau expression drives astrocyte reactivity and dysfunction. JCI Insight 2022; 7:152012. [PMID: 34874917 PMCID: PMC8765054 DOI: 10.1172/jci.insight.152012] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 11/29/2021] [Indexed: 11/22/2022] Open
Abstract
The protein tau and its isoforms are associated with several neurodegenerative diseases, many of which are characterized by greater deposition of the 4-repeat (4R) tau isoform; however, the role of 4R tau in disease pathogenesis remains unclear. We created antisense oligonucleotides (ASOs) that alter the ratio of 3R to 4R tau to investigate the role of specific tau isoforms in disease. Preferential expression of 4R tau in human tau-expressing (hTau-expressing) mice was previously shown to increase seizure severity and phosphorylated tau deposition without neuronal or synaptic loss. In this study, we observed strong colocalization of 4R tau within reactive astrocytes and increased expression of pan-reactive and neurotoxic genes following 3R to 4R tau splicing ASO treatment in hTau mice. Increasing 4R tau levels in primary astrocytes provoked a similar response, including a neurotoxic genetic profile and diminished homeostatic function, which was replicated in human induced pluripotent stem cell-derived (iPSC-derived) astrocytes harboring a mutation that exhibits greater 4R tau. Healthy neurons cultured with 4R tau-expressing human iPSC-derived astrocytes exhibited a higher firing frequency and hypersynchrony, which could be prevented by lowering tau expression. These findings support a potentially novel pathway by which astrocytic 4R tau mediates reactivity and dysfunction and suggest that astrocyte-targeted therapeutics against 4R tau may mitigate neurodegenerative disease progression.
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Affiliation(s)
| | | | | | - Mariana Beltcheva
- Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | | | - Frank Rigo
- Ionis Pharmaceuticals, Carlsbad, California, USA
| | | | - Celeste M. Karch
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
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15
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Wu M, Zhang M, Yin X, Chen K, Hu Z, Zhou Q, Cao X, Chen Z, Liu D. The role of pathological tau in synaptic dysfunction in Alzheimer's diseases. Transl Neurodegener 2021; 10:45. [PMID: 34753506 PMCID: PMC8579533 DOI: 10.1186/s40035-021-00270-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 10/25/2021] [Indexed: 12/12/2022] Open
Abstract
Alzheimer’s disease (AD) is a neurodegenerative disease characterized by progressive cognitive decline, accompanied by amyloid-β (Aβ) overload and hyperphosphorylated tau accumulation in the brain. Synaptic dysfunction, an important pathological hallmark in AD, is recognized as the main cause of the cognitive impairments. Accumulating evidence suggests that synaptic dysfunction could be an early pathological event in AD. Pathological tau, which is detached from axonal microtubules and mislocalized into pre- and postsynaptic neuronal compartments, is suggested to induce synaptic dysfunction in several ways, including reducing mobility and release of presynaptic vesicles, decreasing glutamatergic receptors, impairing the maturation of dendritic spines at postsynaptic terminals, disrupting mitochondrial transport and function in synapses, and promoting the phagocytosis of synapses by microglia. Here, we review the current understanding of how pathological tau mediates synaptic dysfunction and contributes to cognitive decline in AD. We propose that elucidating the mechanism by which pathological tau impairs synaptic function is essential for exploring novel therapeutic strategies for AD.
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Affiliation(s)
- Moxin Wu
- Department of Medical Laboratory, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China.,Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China
| | - Manqing Zhang
- Medical College of Jiujiang University, Jiujiang, 332000, China
| | - Xiaoping Yin
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China.,Department of Neurology, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China
| | - Kai Chen
- Department of Dermatology, Wuhan No. 1 Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Zhijian Hu
- Department of Medical Laboratory, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China
| | - Qin Zhou
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China
| | - Xianming Cao
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China.,Department of Neurology, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China
| | - Zhiying Chen
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, 332000, China. .,Department of Neurology, Affiliated Hospital of Jiujiang University, Jiujiang, 332000, China.
| | - Dan Liu
- Department of Medical Genetics, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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16
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Wander CM, Song J. The neurogenic niche in Alzheimer's disease. Neurosci Lett 2021; 762:136109. [PMID: 34271133 PMCID: PMC9013442 DOI: 10.1016/j.neulet.2021.136109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 06/17/2021] [Accepted: 07/07/2021] [Indexed: 12/15/2022]
Abstract
Adult hippocampal neurogenesis is the process of generation and functional incorporation of new neurons, formed by adult neural stem cells in the dentate gyrus. Adult hippocampal neurogenesis is highly dependent upon the integration of dynamic external stimuli and is instrumental in the formation of new spatial memories. Adult hippocampal neurogenesis is therefore uniquely sensitive to the summation of neuronal circuit and neuroimmune environments that comprise the neurogenic niche, and has powerful implications in diseases of aging and neurological disorders. This sensitivity underlies the neurogenic niche alterations commonly observed in Alzheimer's disease, the most common form of dementia. This review summarizes Alzheimer's disease associated changes in neuronal network activity, neuroinflammatory processes, and adult neural stem cell fate choice that ultimately result in neurogenic niche dysfunction and impaired adult hippocampal neurogenesis. A more comprehensive understanding of the complex changes mediating neurogenic niche disturbances in Alzheimer's disease will aid development of future therapies targeting adult neurogenesis.
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Affiliation(s)
- Connor M Wander
- Department of Pharmacology, University of North Carolina at Chapel Hill
| | - Juan Song
- Department of Pharmacology, University of North Carolina at Chapel Hill
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
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17
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Chung DEC, Roemer S, Petrucelli L, Dickson DW. Cellular and pathological heterogeneity of primary tauopathies. Mol Neurodegener 2021; 16:57. [PMID: 34425874 PMCID: PMC8381569 DOI: 10.1186/s13024-021-00476-x] [Citation(s) in RCA: 88] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 07/22/2021] [Indexed: 12/14/2022] Open
Abstract
Microtubule-associated protein tau is abnormally aggregated in neuronal and glial cells in a range of neurodegenerative diseases that are collectively referred to as tauopathies. Multiple studies have suggested that pathological tau species may act as a seed that promotes aggregation of endogenous tau in naïve cells and contributes to propagation of tau pathology. While they share pathological tau aggregation as a common feature, tauopathies are distinct from one another with respect to predominant tau isoforms that accumulate and the selective vulnerability of brain regions and cell types that have tau inclusions. For instance, primary tauopathies present with glial tau pathology, while it is mostly neuronal in Alzheimer's disease (AD). Also, morphologies of tau inclusions can greatly vary even within the same cell type, suggesting distinct mechanisms or distinct tau conformers in each tauopathy. Neuropathological heterogeneity across tauopathies challenges our understanding of pathophysiology behind tau seeding and aggregation, as well as our efforts to develop effective therapeutic strategies for AD and other tauopathies. In this review, we describe diverse neuropathological features of tau inclusions in neurodegenerative tauopathies and discuss what has been learned from experimental studies with mouse models, advanced transcriptomics, and cryo-electron microscopy (cryo-EM) on the biology underlying cell type-specific tau pathology.
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Affiliation(s)
- Dah-eun Chloe Chung
- Department of Neuroscience, Mayo Clinic, 32224 Jacksonville, FL USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, 77030 Houston, TX USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, 77030 Houston, TX USA
| | - Shanu Roemer
- Department of Neuroscience, Mayo Clinic, 32224 Jacksonville, FL USA
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18
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Lyu S, Guo Y, Zhang L, Tang G, Li R, Yang J, Gao S, Li W, Liu J. Downregulation of astroglial glutamate transporter GLT-1 in the lateral habenula is associated with depressive-like behaviors in a rat model of Parkinson's disease. Neuropharmacology 2021; 196:108691. [PMID: 34197892 DOI: 10.1016/j.neuropharm.2021.108691] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 06/06/2021] [Accepted: 06/24/2021] [Indexed: 01/11/2023]
Abstract
Recent studies show that neuron-glial communication plays an important role in neurological diseases. Particularly, dysfunction of astroglial glutamate transporter GLT-1 has been involved in various neuropsychiatric disorders, including Parkinson's disease (PD) and depression. Our previous studies indicated hyperactivity of neurons in the lateral habenula (LHb) of hemiparkinsonian rats with depressive-like behaviors. Thus, we hypothesized that impaired expression or function of GLT-1 in the LHb might be a potential contributor to LHb hyperactivity, which consequently induces PD-related depression. In the study, unilateral lesions of the substantia nigra pars compacta (SNc) by 6-hydroxydopamine in rats induced depressive-like behaviors and resulted in neuronal hyperactivity as well as increased glutamate levels in the LHb compared to sham-lesioned rats. Intra-LHb injection of GLT-1 inhibitor WAY-213613 induced the depressive-like behaviors in both groups, but the dose producing behavioral effects in the lesioned rats was lower than that of sham-lesioned rats. In the two groups of rats, WAY-213613 increased the firing rate of LHb neurons and extracellular levels of glutamate, and these excitatory effects in the lesioned rats lasted longer than those in sham-lesioned rats. The functional changes of the GLT-1 which primarily expresses in astrocytes in the LHb may attribute to its downregulation after degeneration of the nigrostriatal pathway. Bioinformatics analysis showed that GLT-1 is correlated with various biomarkers of PD and depression risks. Collectively, our study suggests that astroglial GLT-1 in the LHb regulates the firing activity of the neurons, whereupon its downregulation and dysfunction are closely associated with PD-related depression.
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Affiliation(s)
- Shuxuan Lyu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Yuan Guo
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Li Zhang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Guoyi Tang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Ruotong Li
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Jie Yang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Shasha Gao
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Wenjuan Li
- Department of Rehabilitation Medicine, The Second Hospital, Xi'an Jiaotong University, Xi'an, 710004, China
| | - Jian Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China.
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19
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Robert A, Schöll M, Vogels T. Tau Seeding Mouse Models with Patient Brain-Derived Aggregates. Int J Mol Sci 2021; 22:6132. [PMID: 34200180 PMCID: PMC8201271 DOI: 10.3390/ijms22116132] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 05/31/2021] [Accepted: 06/01/2021] [Indexed: 12/23/2022] Open
Abstract
Tauopathies are a heterogeneous class of neurodegenerative diseases characterized by intracellular inclusions of aggregated tau proteins. Tau aggregates in different tauopathies have distinct structural features and can be found in different cell types. Transgenic animal models overexpressing human tau have been used for over two decades in the research of tau pathology. However, these models poorly recapitulate the heterogeneity of tauopathies found in human brains. Recent findings demonstrate that injection of purified tau aggregates from the brains of human tauopathy patients recapitulates both the structural features and cell-type specificity of the tau pathology of the donor tauopathy. These models may therefore have unique translational value in the study of functional consequences of tau pathology, tau-based diagnostics, and tau targeting therapeutics. This review provides an update of the literature relating to seeding-based tauopathy and their potential applications.
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Affiliation(s)
- Aiko Robert
- Department of Neurodegenerative Disease, UCL Queen Square, Institute of Neurology, University College London, London WC1N 3BG, UK; (A.R.); (M.S.)
| | - Michael Schöll
- Department of Neurodegenerative Disease, UCL Queen Square, Institute of Neurology, University College London, London WC1N 3BG, UK; (A.R.); (M.S.)
- Wallenberg Centre for Molecular and Translational Medicine and the Department of Psychiatry and Neurochemistry, University of Gothenburg, 413 45 Gothenburg, Sweden
- Department of Psychiatry and Neurochemistry, University of Gothenburg, 413 45 Gothenburg, Sweden
| | - Thomas Vogels
- Department of Neurodegenerative Disease, UCL Queen Square, Institute of Neurology, University College London, London WC1N 3BG, UK; (A.R.); (M.S.)
- Department of Psychiatry and Neurochemistry, University of Gothenburg, 413 45 Gothenburg, Sweden
- Sylics (Synaptologics B.V.), 3721 MA Bilthoven, The Netherlands
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20
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Ryan RM, Ingram SL, Scimemi A. Regulation of Glutamate, GABA and Dopamine Transporter Uptake, Surface Mobility and Expression. Front Cell Neurosci 2021; 15:670346. [PMID: 33927596 PMCID: PMC8076567 DOI: 10.3389/fncel.2021.670346] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 03/15/2021] [Indexed: 01/31/2023] Open
Abstract
Neurotransmitter transporters limit spillover between synapses and maintain the extracellular neurotransmitter concentration at low yet physiologically meaningful levels. They also exert a key role in providing precursors for neurotransmitter biosynthesis. In many cases, neurons and astrocytes contain a large intracellular pool of transporters that can be redistributed and stabilized in the plasma membrane following activation of different signaling pathways. This means that the uptake capacity of the brain neuropil for different neurotransmitters can be dynamically regulated over the course of minutes, as an indirect consequence of changes in neuronal activity, blood flow, cell-to-cell interactions, etc. Here we discuss recent advances in the mechanisms that control the cell membrane trafficking and biophysical properties of transporters for the excitatory, inhibitory and modulatory neurotransmitters glutamate, GABA, and dopamine.
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Affiliation(s)
- Renae M. Ryan
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Susan L. Ingram
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, United States
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21
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Maté de Gérando A, d'Orange M, Augustin E, Joséphine C, Aurégan G, Gaudin-Guérif M, Guillermier M, Hérard AS, Stimmer L, Petit F, Gipchtein P, Jan C, Escartin C, Selingue E, Carvalho K, Blum D, Brouillet E, Hantraye P, Gaillard MC, Bonvento G, Bemelmans AP, Cambon K. Neuronal tau species transfer to astrocytes and induce their loss according to tau aggregation state. Brain 2021; 144:1167-1182. [PMID: 33842937 DOI: 10.1093/brain/awab011] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 09/24/2020] [Accepted: 11/01/2020] [Indexed: 11/12/2022] Open
Abstract
Deposits of different abnormal forms of tau in neurons and astrocytes represent key anatomo-pathological features of tauopathies. Although tau protein is highly enriched in neurons and poorly expressed by astrocytes, the origin of astrocytic tau is still elusive. Here, we used innovative gene transfer tools to model tauopathies in adult mouse brains and to investigate the origin of astrocytic tau. We showed in our adeno-associated virus (AAV)-based models and in Thy-Tau22 transgenic mice that astrocytic tau pathology can emerge secondarily to neuronal pathology. By designing an in vivo reporter system, we further demonstrated bidirectional exchanges of tau species between neurons and astrocytes. We then determined the consequences of tau accumulation in astrocytes on their survival in models displaying various status of tau aggregation. Using stereological counting of astrocytes, we report that, as for neurons, soluble tau species are highly toxic to some subpopulations of astrocytes in the hippocampus, whereas the accumulation of tau aggregates does not affect their survival. Thus, astrocytes are not mere bystanders of neuronal pathology. Our results strongly suggest that tau pathology in astrocytes may significantly contribute to clinical symptoms.
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Affiliation(s)
- Anastasie Maté de Gérando
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Marie d'Orange
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Emma Augustin
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Charlène Joséphine
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Gwénaelle Aurégan
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Mylène Gaudin-Guérif
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Martine Guillermier
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Anne-Sophie Hérard
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Lev Stimmer
- MIRCen, INSERM-CEA, Platform for experimental pathology, U1169 and US27, F-92265 Fontenay-aux-Roses, France
| | - Fanny Petit
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Pauline Gipchtein
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Caroline Jan
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Carole Escartin
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Erwan Selingue
- Université Paris-Saclay, CEA, Neurospin, 91191, Gif-sur-Yvette, France
| | - Kévin Carvalho
- Université Lille, Inserm, CHU Lille, U1172-LilNCog-Lille Neuroscience and Cognition, F-59000 Lille, France.,Alzheimer and Tauopathies, LabEx DISTALZ, Lille, France
| | - David Blum
- Université Lille, Inserm, CHU Lille, U1172-LilNCog-Lille Neuroscience and Cognition, F-59000 Lille, France.,Alzheimer and Tauopathies, LabEx DISTALZ, Lille, France
| | - Emmanuel Brouillet
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Philippe Hantraye
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Marie-Claude Gaillard
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Gilles Bonvento
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Alexis-Pierre Bemelmans
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Karine Cambon
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
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22
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Ungerleider K, Beck J, Lissa D, Turnquist C, Horikawa I, Harris BT, Harris CC. Astrocyte senescence and SASP in neurodegeneration: tau joins the loop. Cell Cycle 2021; 20:752-764. [PMID: 33818291 DOI: 10.1080/15384101.2021.1909260] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Tau accumulation is a core component of Alzheimer's disease and other neurodegenerative tauopathies. While tau's impact on neurons is a major area of research, the effect of extracellular tau on astrocytes is largely unknown. This article summarizes our recent studies showing that astrocyte senescence plays a critical role in neurodegenerative diseases and integrates extracellular tau into the regulatory loop of senescent astrocyte-mediated neurotoxicity. Human astrocytes in vitro undergoing senescence were shown to acquire the inflammatory senescence-associated secretory phenotype (SASP) and toxicity to neurons, which may recapitulate aging- and disease-associated neurodegeneration. Here, we show that human astrocytes exposed to extracellular tau in vitro also undergo cellular senescence and acquire a neurotoxic SASP (e.g. IL-6 secretion), with oxidative stress response (indicated by upregulated NRF2 target genes) and a possible activation of inflammasome (indicated by upregulated ASC and IL-1β). These findings suggest that senescent astrocytes induced by various conditions and insults, including tau exposure, may represent a therapeutic target to inhibit or delay the progression of neurodegenerative diseases. We also discuss the pathological activity of extracellular tau in microglia and astrocytes, the disease relevance and diversity of tau forms, therapeutics targeting senescence in neurodegeneration, and the roles of p53 and its isoforms in astrocyte-mediated neurotoxicity and neuroprotection.
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Affiliation(s)
- Kyra Ungerleider
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jessica Beck
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.,Department of Comparative Pathobiology, Purdue University, West Layfette, Indiana, USA
| | - Delphine Lissa
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Casmir Turnquist
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.,University of Oxford Medical School, John Radcliffe Hospital, Oxford, UK
| | - Izumi Horikawa
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Brent T Harris
- Department of Neurology, Georgetown University Medical Center, Washington, DC, USA
| | - Curtis C Harris
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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23
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Fleeman RM, Proctor EA. Astrocytic Propagation of Tau in the Context of Alzheimer's Disease. Front Cell Neurosci 2021; 15:645233. [PMID: 33815065 PMCID: PMC8010320 DOI: 10.3389/fncel.2021.645233] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 02/19/2021] [Indexed: 01/14/2023] Open
Abstract
More than 6 million Americans are currently living with Alzheimer's disease (AD), and the incidence is growing rapidly with our aging population. Numerous therapeutics have failed to make it to the clinic, potentially due to a focus on presumptive pathogenic proteins instead of cell-type-specific signaling mechanisms. The tau propagation hypothesis that inter-neuronal tau transfer drives AD pathology has recently garnered attention, as accumulation of pathological tau in the brain has high clinical significance in correlating with progression of cognitive AD symptoms. However, studies on tau pathology in AD are classically neuron-centric and have greatly overlooked cell-type specific effects of tau internalization, degradation, and propagation. While the contribution of microglia to tau processing and propagation is beginning to be recognized and understood, astrocytes, glial cells in the brain important for maintaining neuronal metabolic, synaptic, trophic, and immune function which can produce, internalize, degrade, and propagate tau are understudied in their ability to affect AD progression through tau pathology. Here, we showcase evidence for whether tau uptake by astrocytes may be beneficial or detrimental to neuronal health and how astrocytes and their immunometabolic functions may be key targets for future successful AD therapies.
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Affiliation(s)
- Rebecca M Fleeman
- Department of Neurosurgery, Department of Pharmacology, College of Medicine, Pennsylvania State University (PSU), Hershey, PA, United States.,Center for Neural Engineering, Pennsylvania State University (PSU), University Park, PA, United States
| | - Elizabeth A Proctor
- Department of Neurosurgery, Department of Pharmacology, College of Medicine, Pennsylvania State University (PSU), Hershey, PA, United States.,Department of Biomedical Engineering, Department of Engineering Science and Mechanics, Center for Neural Engineering, Pennsylvania State University (PSU), University Park, PA, United States
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24
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Brymer KJ, Barnes JR, Parsons MP. Entering a new era of quantifying glutamate clearance in health and disease. J Neurosci Res 2021; 99:1598-1617. [PMID: 33618436 DOI: 10.1002/jnr.24810] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 01/22/2021] [Accepted: 02/01/2021] [Indexed: 12/21/2022]
Abstract
Glutamate transporter proteins, expressed on both neurons and glia, serve as the main gatekeepers that dictate the spatial and temporal actions of extracellular glutamate. Glutamate is essential to the function of the healthy brain yet paradoxically contributes to the toxicity associated with many neurodegenerative diseases. Rapid transporter-mediated glutamate uptake, primarily occurring at astrocytic processes, tightens the efficiency of excitatory network activity and prevents toxic glutamate build-up in the extracellular space. Glutamate transporter dysfunction is thought to underlie myriad central nervous system (CNS) diseases including Alzheimer and Huntington disease. Over the past few decades, techniques such as biochemical uptake assays and electrophysiological recordings of transporter currents from individual astrocytes have revealed the remarkable ability of the CNS to efficiently clear extracellular glutamate. In more recent years, the rapidly evolving glutamate-sensing "sniffers" now allow researchers to visualize real-time glutamate transients on a millisecond time scale with single synapse spatial resolution in defined cell populations. As we transition to an increased reliance on optical-based methods of glutamate visualization and quantification, it is of utmost importance to understand not only the advantages that glutamate biosensors bring to the table but also the associated caveats and their implications for data interpretation. In this review, we summarize the strengths and limitations of the commonly used methods to quantify glutamate uptake. We then discuss what these techniques, when viewed as a complementary whole, have told us about the brain's ability to regulate glutamate levels, in both health and in the context of neurodegenerative disease.
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Affiliation(s)
- Kyle J Brymer
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Jocelyn R Barnes
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Matthew P Parsons
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
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25
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Acioglu C, Li L, Elkabes S. Contribution of astrocytes to neuropathology of neurodegenerative diseases. Brain Res 2021; 1758:147291. [PMID: 33516810 DOI: 10.1016/j.brainres.2021.147291] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 12/10/2020] [Accepted: 01/05/2021] [Indexed: 02/08/2023]
Abstract
Classically, the loss of vulnerable neuronal populations in neurodegenerative diseases was considered to be the consequence of cell autonomous degeneration of neurons. However, progress in the understanding of glial function, the availability of improved animal models recapitulating the features of the human diseases, and the development of new approaches to derive glia and neurons from induced pluripotent stem cells obtained from patients, provided novel information that altered this view. Current evidence strongly supports the notion that non-cell autonomous mechanisms contribute to the demise of neurons in neurodegenerative disorders, and glia causally participate in the pathogenesis and progression of these diseases. In addition to microglia, astrocytes have emerged as key players in neurodegenerative diseases and will be the focus of the present review. Under the influence of pathological stimuli present in the microenvironment of the diseased CNS, astrocytes undergo morphological, transcriptional, and functional changes and become reactive. Reactive astrocytes are heterogeneous and exhibit neurotoxic (A1) or neuroprotective (A2) phenotypes. In recent years, single-cell or single-nucleus transcriptome analyses unraveled new, disease-specific phenotypes beyond A1/A2. These investigations highlighted the complexity of the astrocytic responses to CNS pathology. The present review will discuss the contribution of astrocytes to neurodegenerative diseases with particular emphasis on Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and frontotemporal dementia. Some of the commonalties and differences in astrocyte-mediated mechanisms that possibly drive the pathogenesis or progression of the diseases will be summarized. The emerging view is that astrocytes are potential new targets for therapeutic interventions. A comprehensive understanding of astrocyte heterogeneity and disease-specific phenotypic complexity could facilitate the design of novel strategies to treat neurodegenerative disorders.
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Affiliation(s)
- Cigdem Acioglu
- The Reynolds Family Spine Laboratory, Department of Neurological Surgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, United States.
| | - Lun Li
- The Reynolds Family Spine Laboratory, Department of Neurological Surgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, United States.
| | - Stella Elkabes
- The Reynolds Family Spine Laboratory, Department of Neurological Surgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, United States.
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26
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Posada-Duque RA, Cardona-Gómez GP. CDK5 Targeting as a Therapy for Recovering Neurovascular Unit Integrity in Alzheimer's Disease. J Alzheimers Dis 2020; 82:S141-S161. [PMID: 33016916 DOI: 10.3233/jad-200730] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The neurovascular unit (NVU) is responsible for synchronizing the energetic demand, vasodynamic changes, and neurochemical and electrical function of the brain through a closed and interdependent interaction of cell components conforming to brain tissue. In this review, we will focus on cyclin-dependent kinase 5 (CDK5) as a molecular pivot, which plays a crucial role in the healthy function of neurons, astrocytes, and the endothelium and is implicated in the cross-talk of cellular adhesion signaling, ion transmission, and cytoskeletal remodeling, thus allowing the individual and interconnected homeostasis of cerebral parenchyma. Then, we discuss how CDK5 overactivation affects the integrity of the NVU in Alzheimer's disease (AD) and cognitive impairment; we emphasize how CDK5 is involved in the excitotoxicity spreading of glutamate and Ca2+ imbalance under acute and chronic injury. Additionally, we present pharmacological and gene therapy strategies for producing partial depletion of CDK5 activity on neurons, astrocytes, or endothelium to recover neuroplasticity and neurotransmission, suggesting that the NVU should be the targeted tissue unit in protective strategies. Finally, we conclude that CDK5 could be effective due to its intervention on astrocytes by its end feet on the endothelium and neurons, acting as an intermediary cell between systemic and central communication in the brain. This review provides integrated guidance regarding the pathogenesis of and potential repair strategies for AD.
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Affiliation(s)
- Rafael Andrés Posada-Duque
- Cellular and Molecular Neurobiology Area, Group of Neuroscience of Antioquia, SIU, University of Antioquia, Medellín, Colombia.,Institute of Biology, Faculty of Exact and Natural Sciences, University of Antioquia, Medellín, Colombia
| | - Gloria Patricia Cardona-Gómez
- Cellular and Molecular Neurobiology Area, Group of Neuroscience of Antioquia, SIU, University of Antioquia, Medellín, Colombia
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27
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Koller EJ, Chakrabarty P. Tau-Mediated Dysregulation of Neuroplasticity and Glial Plasticity. Front Mol Neurosci 2020; 13:151. [PMID: 32973446 PMCID: PMC7472665 DOI: 10.3389/fnmol.2020.00151] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/20/2020] [Indexed: 01/14/2023] Open
Abstract
The inability of individual neurons to compensate for aging-related damage leads to a gradual loss of functional plasticity in the brain accompanied by progressive impairment in learning and memory. Whereas this loss in neuroplasticity is gradual during normal aging, in neurodegenerative diseases such as Alzheimer’s disease (AD), this loss is accelerated dramatically, leading to the incapacitation of patients within a decade of onset of cognitive symptoms. The mechanisms that underlie this accelerated loss of neuroplasticity in AD are still not completely understood. While the progressively increasing proteinopathy burden, such as amyloid β (Aβ) plaques and tau tangles, definitely contribute directly to a neuron’s functional demise, the role of non-neuronal cells in controlling neuroplasticity is slowly being recognized as another major factor. These non-neuronal cells include astrocytes, microglia, and oligodendrocytes, which through regulating brain homeostasis, structural stability, and trophic support, play a key role in maintaining normal functioning and resilience of the neuronal network. It is believed that chronic signaling from these cells affects the homeostatic network of neuronal and non-neuronal cells to an extent to destabilize this harmonious milieu in neurodegenerative diseases like AD. Here, we will examine the experimental evidence regarding the direct and indirect pathways through which astrocytes and microglia can alter brain plasticity in AD, specifically as they relate to the development and progression of tauopathy. In this review article, we describe the concepts of neuroplasticity and glial plasticity in healthy aging, delineate possible mechanisms underlying tau-induced plasticity dysfunction, and discuss current clinical trials as well as future disease-modifying approaches.
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Affiliation(s)
- Emily J Koller
- Department of Neuroscience, University of Florida, Gainesville, FL, United States.,Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, United States
| | - Paramita Chakrabarty
- Department of Neuroscience, University of Florida, Gainesville, FL, United States.,Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, United States.,McKnight Brain Institute, University of Florida, Gainesville, FL, United States
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28
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Means JC, Lopez AA, Koulen P. Resveratrol Protects Optic Nerve Head Astrocytes from Oxidative Stress-Induced Cell Death by Preventing Caspase-3 Activation, Tau Dephosphorylation at Ser 422 and Formation of Misfolded Protein Aggregates. Cell Mol Neurobiol 2020; 40:911-926. [PMID: 31919747 PMCID: PMC7299779 DOI: 10.1007/s10571-019-00781-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 12/23/2019] [Indexed: 12/19/2022]
Abstract
Optic nerve head astrocytes (ONHAs) are the major cell type within the optic nerve head, providing both structural and nutrient support to the optic nerve. Astrocytes are necessary for the survival of neurons with controlled activation of astrocytes being beneficial to neurons. However, overactive astrocytes can be harmful and the loss of normal astrocyte function can be a primary contributor to neurodegeneration. The neuroprotective properties of reactive astrocytes can be lost or they might gain neurotoxic properties in neurodegenerative diseases. The activated astrocytes are crucial in the development of glaucoma, where they serve as a source for cytotoxic substances that participate in ganglion apoptosis. There is increasing evidence indicating that neuroinflammation is an important process in glaucoma. Under pathological conditions, astrocytes can induce an inflammatory response. Extensive evidence shows that inflammatory responses mediated by astrocytes can also influence pathology development, synapse health, and neurodegeneration. The elimination of activated astrocytes by apoptosis is also expected in unfavorable conditions. In neurodegenerative diseases, a common feature is the presence of aggregates found in astrocytes, which can disrupt astrocyte function in such a way as to be detrimental to the viability of neurons. The biological processes involved in vision loss in glaucoma are not well understood. Despite the rapid advances in our understanding of optic nerve head (ONH) structure and function, numerous potential contributions of the ONHAs to optic nerve damage remain unanswered. The present study investigated the role of ONHAs during oxidative stress in order to determine novel cell biological processes underlying glaucoma pathogenesis. ONHAs were exposed to chemically induced oxidative stress using tert-butyl hydroperoxide (tBHP) in order to model extracellular oxidative stress as it occurs in the glaucomatous retina and ONH. In order to determine the impact of an intervention approach employing potential glioprotective treatments for central nervous system tissue we pretreated cells with the polyphenolic phytostilbene and antioxidant trans-resveratrol (3,5,4'-trihydroxy-trans-stilbene). ONHAs exposed to tBHP-mediated oxidative stress displayed decreased viability and underwent apoptosis. In addition, increased levels of activated caspases, dephosphorylation of Tau protein at Ser422, an important site adjacent to the caspase cleavage site controlling Tau cleavage, caspase-mediated Tau cleavage, and cytoskeletal changes, specifically formation of neurofibrillary tangles (NFTs) were detected in ONHAs undergoing oxidative stress. When cells were pretreated with resveratrol cell viability increased along with a significant decrease in activated caspases, cleaved Tau, and NFT formation. Taken together, ONHAs appear to act similar to neurons when undergoing oxidative stress, where proteolytic cleavage of Tau by caspases leads to NFT formation. In addition, resveratrol appears to have promise as a potential protective treatment preventing ONHA dysfunction and degeneration. There is currently no cure for glaucoma or a neuro- and glioprotective treatment that directly targets the pathogenic mechanisms in the glaucomatous retina and optic nerve. The present study identified a potential mechanism underlying degeneration of astrocytes that is susceptible to pharmaco-therapeutic intervention in the eye and potentially elsewhere in the central nervous system. Identification of such mechanisms involved in glaucoma and other disorders of the eye and brain is critical to determine novel targets for effective therapies.
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Affiliation(s)
- John C Means
- Vision Research Center, Department of Ophthalmology, School of Medicine, University of Missouri -Kansas City, 2411 Holmes St, Kansas City, MO, 64108, USA
| | - Adam A Lopez
- Vision Research Center, Department of Ophthalmology, School of Medicine, University of Missouri -Kansas City, 2411 Holmes St, Kansas City, MO, 64108, USA
| | - Peter Koulen
- Vision Research Center, Department of Ophthalmology, School of Medicine, University of Missouri -Kansas City, 2411 Holmes St, Kansas City, MO, 64108, USA.
- Department of Biomedical Sciences, School of Medicine, University of Missouri -Kansas City, 2411 Holmes St, Kansas City, MO, 64108, USA.
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29
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Astroglial contribution to tau-dependent neurodegeneration. Biochem J 2020; 476:3493-3504. [PMID: 31774919 DOI: 10.1042/bcj20190506] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 11/07/2019] [Accepted: 11/08/2019] [Indexed: 01/31/2023]
Abstract
Astrocytes, by maintaining an optimal environment for neuronal function, play a critical role in proper function of mammalian nervous system. They regulate synaptic transmission and plasticity and protect neurons against toxic insults. Astrocytes and neurons interact actively via glutamine-glutamate cycle (GGC) that supports neuronal metabolic demands and neurotransmission. GGC deficiency may be involved in different diseases of the brain, where impaired astrocytic control of glutamate homeostasis contributes to neuronal dysfunction. This includes tau-dependent neurodegeneration, where astrocytes lose key molecules involved in regulation of glutamate/glutamine homeostasis, neuronal survival and synaptogenesis. Astrocytic dysfunction in tauopathy appears to precede neurodegeneration and overt tau neuropathology such as phosphorylation, aggregation and formation of neurofibrillary tangles. In this review, we summarize recent studies demonstrating that activation of astrocytes is strictly associated with neurodegenerative processes including those involved in tau related pathology. We propose that astrocytic dysfunction, by disrupting the proper neuron-glia signalling early in the disease, significantly contributes to tauopathy pathogenesis.
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30
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Ferrer I, Andrés-Benito P, Zelaya MV, Aguirre MEE, Carmona M, Ausín K, Lachén-Montes M, Fernández-Irigoyen J, Santamaría E, del Rio JA. Familial globular glial tauopathy linked to MAPT mutations: molecular neuropathology and seeding capacity of a prototypical mixed neuronal and glial tauopathy. Acta Neuropathol 2020; 139:735-771. [PMID: 31907603 PMCID: PMC7096369 DOI: 10.1007/s00401-019-02122-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/23/2019] [Accepted: 12/23/2019] [Indexed: 12/11/2022]
Abstract
Globular glial tauopathy (GGT) is a progressive neurodegenerative disease involving the grey matter and white matter (WM) and characterized by neuronal deposition of hyper-phosphorylated, abnormally conformed, truncated, oligomeric 4Rtau in neurons and in glial cells forming typical globular astrocyte and oligodendrocyte inclusions (GAIs and GOIs, respectively) and coiled bodies. Present studies centre on four genetic GGT cases from two unrelated families bearing the P301T mutation in MAPT and one case of sporadic GGT (sGGT) and one case of GGT linked to MAPT K317M mutation, for comparative purposes. Clinical and neuropathological manifestations and biochemical profiles of phospho-tau are subjected to individual variations in patients carrying the same mutation, even in carriers of the same family, independently of the age of onset, gender, and duration of the disease. Immunohistochemistry, western blotting, transcriptomic, proteomics and phosphoproteomics, and intra-cerebral inoculation of brain homogenates to wild-type (WT) mice were the methods employed. In GGT cases linked to MAPT P301T mutation, astrocyte markers GFAP, ALDH1L1, YKL40 mRNA and protein, GJA1 mRNA, and AQ4 protein are significantly increased; glutamate transporter GLT1 (EAAT2) and glucose transporter (SLC2A1) decreased; mitochondrial pyruvate carrier 1 (MPC1) increased, and mitochondrial uncoupling protein 5 (UCP5) almost absent in GAIs in frontal cortex (FC). Expression of oligodendrocyte markers OLIG1 and OLIG2mRNA, and myelin-related genes MBP, PLP1, CNP, MAG, MAL, MOG, and MOBP are significantly decreased in WM; CNPase, PLP1, and MBP antibodies reveal reduction and disruption of myelinated fibres; and SMI31 antibodies mark axonal damage in the WM. Altered expression of AQ4, GLUC-t, and GLT-1 is also observed in sGGT and in GGT linked to MAPT K317M mutation. These alterations point to primary astrogliopathy and oligodendrogliopathy in GGT. In addition, GGT linked to MAPT P301T mutation proteotypes unveil a proteostatic imbalance due to widespread (phospho)proteomic dearrangement in the FC and WM, triggering a disruption of neuron projection morphogenesis and synaptic transmission. Identification of hyper-phosphorylation of variegated proteins calls into question the concept of phospho-tau-only alteration in the pathogenesis of GGT. Finally, unilateral inoculation of sarkosyl-insoluble fractions of GGT homogenates from GGT linked to MAPT P301T, sGGT, and GGT linked to MAPT K317M mutation in the hippocampus, corpus callosum, or caudate/putamen in wild-type mice produces seeding, and time- and region-dependent spreading of phosphorylated, non-oligomeric, and non-truncated 4Rtau and 3Rtau, without GAIs and GOIs but only of coiled bodies. These experiments prove that host tau strains are important in the modulation of cellular vulnerability and phenotypes of phospho-tau aggregates.
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31
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Müller-Thomsen L, Borgmann D, Morcinek K, Schröder S, Dengler B, Moser N, Neumaier F, Schneider T, Schröder H, Huggenberger S. Consequences of hyperphosphorylated tau on the morphology and excitability of hippocampal neurons in aged tau transgenic mice. Neurobiol Aging 2020; 93:109-123. [PMID: 32278495 DOI: 10.1016/j.neurobiolaging.2020.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 03/06/2020] [Accepted: 03/10/2020] [Indexed: 12/31/2022]
Abstract
The intracellular accumulation of hyperphosphorylated tau characterizes many neurodegenerative diseases such as Alzheimer's disease and frontotemporal dementia. A critical role for tau is supported by studies in transgenic mouse models expressing the P301L mutation with accumulation of hyperphosphorylated human tau in hippocampal pyramidal neurons of aged mice. Especially, the somatodendritic mislocalization of hyperphosphorylated tau seems to affect the neuronal network of the hippocampus. To show the consequences of aggregation of hyperphosphorylated tau within hippocampal neurons of aged mice, the CA1 pyramidal cells were analyzed morphologically and electrophysiologically. Here we demonstrate in the P301L pR5 mouse model that hyperphosphorylated tau leads to an increase in stubby spines and filopodia, as well as a decrease in total dendritic length of hippocampal pyramidal neurons due to a decrease in apical dendritic length and nodes. This atrophy is in line with the significant reduction in CA1 long-term potentiation. Furthermore, mutant tau induced a depolarized threshold for action potential initiation and an increased current of inward rectifying potassium channels, which should lead, together with the long-term potentiation decrease, to a decreased excitability of CA1 neurons.
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Affiliation(s)
| | - Diba Borgmann
- Department II of Anatomy, University of Cologne, Cologne, Germany
| | - Kerstin Morcinek
- Department II of Anatomy, University of Cologne, Cologne, Germany
| | - Sophia Schröder
- Department II of Anatomy, University of Cologne, Cologne, Germany
| | - Brigitte Dengler
- Department II of Anatomy, University of Cologne, Cologne, Germany
| | - Natasha Moser
- Department II of Anatomy, University of Cologne, Cologne, Germany
| | - Felix Neumaier
- Institute for Neurophysiology, University of Cologne, Cologne, Germany
| | - Toni Schneider
- Institute for Neurophysiology, University of Cologne, Cologne, Germany
| | | | - Stefan Huggenberger
- Department II of Anatomy, University of Cologne, Cologne, Germany; Institute of Anatomy and Clinical Morphology, Faculty of Health, Witten/Herdecke University, Witten, Germany
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32
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Guillemaud O, Ceyzériat K, Saint-Georges T, Cambon K, Petit F, Ben Haim L, Carrillo-de Sauvage MA, Guillermier M, Bernier S, Hérard AS, Joséphine C, Bémelmans AP, Brouillet E, Hantraye P, Bonvento G, Escartin C. Complex roles for reactive astrocytes in the triple transgenic mouse model of Alzheimer disease. Neurobiol Aging 2020; 90:135-146. [PMID: 32171592 DOI: 10.1016/j.neurobiolaging.2020.02.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/06/2020] [Accepted: 02/12/2020] [Indexed: 12/29/2022]
Abstract
In Alzheimer disease (AD), astrocytes undergo complex changes and become reactive. The consequences of this reaction are still unclear. To evaluate the net impact of reactive astrocytes in AD, we developed viral vectors targeting astrocytes that either activate or inhibit the Janus kinase-signal transducer and activator of transcription 3 (JAK2-STAT3) pathway, a central cascade controlling astrocyte reaction. We aimed to evaluate whether reactive astrocytes contribute to tau as well as amyloid pathologies in the hippocampus of 3xTg-AD mice, an AD model that develops tau hyper-phosphorylation and amyloid deposition. JAK2-STAT3 pathway-mediated modulation of reactive astrocytes in 25% of the hippocampus of 3xTg-AD mice did not significantly influence tau phosphorylation or amyloid processing and deposition at early, advanced, and terminal disease stage. Interestingly, inhibition of the JAK2-STAT3 pathway in hippocampal astrocytes did not improve spatial memory in the Y maze but it did reduce anxiety in the elevated plus maze. Our unique approach to specifically manipulate reactive astrocytes in situ show they may impact behavioral outcomes without influencing tau or amyloid pathology.
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Affiliation(s)
- Océane Guillemaud
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Kelly Ceyzériat
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Thomas Saint-Georges
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Karine Cambon
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Fanny Petit
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Lucile Ben Haim
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | | | - Martine Guillermier
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Sueva Bernier
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Anne-Sophie Hérard
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Charlène Joséphine
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Alexis Pierre Bémelmans
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Emmanuel Brouillet
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Philippe Hantraye
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Gilles Bonvento
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Carole Escartin
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France.
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Kery R, Chen APF, Kirschen GW. Genetic targeting of astrocytes to combat neurodegenerative disease. Neural Regen Res 2020; 15:199-211. [PMID: 31552885 PMCID: PMC6905329 DOI: 10.4103/1673-5374.265541] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Astrocytes, glial cells that interact extensively with neurons and other support cells throughout the central nervous system, have recently come under the spotlight for their potential contribution to, or potential regenerative role in a host of neurodegenerative disorders. It is becoming increasingly clear that astrocytes, in concert with microglial cells, activate intrinsic immunological pathways in the setting of neurodegenerative injury, although the direct and indirect consequences of such activation are still largely unknown. We review the current literature on the astrocyte’s role in several neurodegenerative diseases, as well as highlighting recent advances in genetic manipulation of astrocytes that may prove critical to modulating their response to neurological injury, potentially combatting neurodegenerative damage.
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Affiliation(s)
- Rachel Kery
- Medical Scientist Training Program (MSTP), Stony Brook Medicine; Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY, USA
| | - Allen P F Chen
- Medical Scientist Training Program (MSTP), Stony Brook Medicine; Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY, USA
| | - Gregory W Kirschen
- Medical Scientist Training Program (MSTP), Stony Brook Medicine, Stony Brook, NY, USA
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Van Erum J, Valkenburg F, Van Dam D, De Deyn PP. Pentylenetetrazole-induced Seizure Susceptibility in the Tau58/4 Transgenic Mouse Model of Tauopathy. Neuroscience 2019; 425:112-122. [PMID: 31785360 DOI: 10.1016/j.neuroscience.2019.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 11/04/2019] [Accepted: 11/05/2019] [Indexed: 11/19/2022]
Abstract
In several tauopathies such as Alzheimer's disease (AD), an increased incidence of seizures is observed. Tau, one of the major proteins implicated in AD pathology, is an important regulator of neural network excitability and might participate in the underlying epileptic cascade. However, the mechanisms underlying this relationship are not fully elucidated. We aim to investigate this mechanism by analyzing seizure susceptibility to the convulsant pentylenetetrazole (PTZ) in a novel rodent tauopathy model. A single dose of PTZ was systemically injected in Tau58/4 transgenic mice. To investigate whether young and aged heterozygous (HET) mice exhibit a higher susceptibility to seizures in comparison with wild-type (WT) littermates, video electroencephalography (EEG) in combination with behavioral scoring according to a modified Racine scale was used. The employment of different dosage groups enabled us to characterize the dose range reliably inducing seizures. Here, we report an increased seizure susceptibility in young but not in old HET Tau58/4 mice. Young HET animals displayed more severe seizures and had a reduced latency to the first seizure compared to WTs. Also, age-related differences in susceptibility could be demonstrated for both genotypes. Identification and targeting of secondary diseases such as epilepsy, which aggravate dementia and lead to earlier institutionalization, is key. This study finds that tau pathology itself is sufficient to alter seizure susceptibility in a rodent model, indicating that the disease process is crucial in the emergence of epilepsy in patients with tauopathy.
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Affiliation(s)
- Jan Van Erum
- Laboratory of Neurochemistry and Behavior, Institute Born-Bunge, Department of Biomedical Sciences, University of Antwerp, Wilrijk (Antwerp), Belgium
| | - Femke Valkenburg
- Laboratory of Neurochemistry and Behavior, Institute Born-Bunge, Department of Biomedical Sciences, University of Antwerp, Wilrijk (Antwerp), Belgium
| | - Debby Van Dam
- Laboratory of Neurochemistry and Behavior, Institute Born-Bunge, Department of Biomedical Sciences, University of Antwerp, Wilrijk (Antwerp), Belgium; Department of Neurology and Alzheimer Center, University of Groningen and University Medical Center Groningen (UMCG), Groningen, The Netherlands
| | - Peter Paul De Deyn
- Laboratory of Neurochemistry and Behavior, Institute Born-Bunge, Department of Biomedical Sciences, University of Antwerp, Wilrijk (Antwerp), Belgium; Department of Neurology and Alzheimer Center, University of Groningen and University Medical Center Groningen (UMCG), Groningen, The Netherlands; Department of Neurology, Memory Clinic of Hospital Network Antwerp (ZNA) Middelheim and Hoge Beuken, Antwerp, Belgium.
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Vogels T, Murgoci AN, Hromádka T. Intersection of pathological tau and microglia at the synapse. Acta Neuropathol Commun 2019; 7:109. [PMID: 31277708 PMCID: PMC6612163 DOI: 10.1186/s40478-019-0754-y] [Citation(s) in RCA: 116] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 06/19/2019] [Indexed: 02/07/2023] Open
Abstract
Tauopathies are a heterogenous class of diseases characterized by cellular accumulation of aggregated tau and include diseases such as Alzheimer’s disease (AD), progressive supranuclear palsy and chronic traumatic encephalopathy. Tau pathology is strongly linked to neurodegeneration and clinical symptoms in tauopathy patients. Furthermore, synapse loss is an early pathological event in tauopathies and is the strongest correlate of cognitive decline. Tau pathology is additionally associated with chronic neuroinflammatory processes, such as reactive microglia, astrocytes, and increased levels of pro-inflammatory molecules (e.g. complement proteins, cytokines). Recent studies show that as the principal immune cells of the brain, microglia play a particularly important role in the initiation and progression of tau pathology and associated neurodegeneration. Furthermore, AD risk genes such as Triggering receptor expressed on myeloid cells 2 (TREM2) and Apolipoprotein E (APOE) are enriched in the innate immune system and modulate the neuroinflammatory response of microglia to tau pathology. Microglia can play an active role in synaptic dysfunction by abnormally phagocytosing synaptic compartments of neurons with tau pathology. Furthermore, microglia are involved in synaptic spreading of tau – a process which is thought to underlie the progressive nature of tau pathology propagation through the brain. Spreading of pathological tau is also the predominant target for tau-based immunotherapy. Active tau vaccines, therapeutic tau antibodies and other approaches targeting the immune system are actively explored as treatment options for AD and other tauopathies. This review describes the role of microglia in the pathobiology of tauopathies and the mechanism of action of potential therapeutics targeting the immune system in tauopathies.
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Factors other than hTau overexpression that contribute to tauopathy-like phenotype in rTg4510 mice. Nat Commun 2019; 10:2479. [PMID: 31171783 PMCID: PMC6554306 DOI: 10.1038/s41467-019-10428-1] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 05/10/2019] [Indexed: 12/17/2022] Open
Abstract
The tauopathy-like phenotype observed in the rTg4510 mouse line, in which human tauP301L expression specifically within the forebrain can be temporally controlled, has largely been attributed to high overexpression of mutant human tau in the forebrain region. Unexpectedly, we found that in a different mouse line with a targeted-insertion of the same transgene driven by the same tetracycline-TransActivator (tTA) allele, but with even higher overexpression of tauP301L than rTg4510, atrophy and tau histopathology are delayed, and a different behavioral profile is observed. This suggests that it is not overexpression of mutant human tau alone that contributes to the phenotype in rTg4510 mice. Furthermore we show that the tauopathy-like phenotype seen in rTg4510 requires a ~70-copy tau-transgene insertion in a 244 kb deletion in Fgf14, a ~7-copy tTA-transgene insertion in a 508 kb deletion that disrupts another five genes, in addition to high transgene overexpression. We propose that these additional effects need to be accounted for in any studies using rTg4510.
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You Y, Perkins A, Cisternas P, Muñoz B, Taylor X, You Y, Garringer HJ, Oblak AL, Atwood BK, Vidal R, Lasagna-Reeves CA. Tau as a mediator of neurotoxicity associated to cerebral amyloid angiopathy. Acta Neuropathol Commun 2019; 7:26. [PMID: 30808415 PMCID: PMC6390363 DOI: 10.1186/s40478-019-0680-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Accepted: 02/17/2019] [Indexed: 12/20/2022] Open
Abstract
Cerebral amyloid angiopathy (CAA) is typified by the cerebrovascular deposition of amyloid. Currently, there is no clear understanding of the mechanisms underlying the contribution of CAA to neurodegeneration. Despite the fact that CAA is highly associated with accumulation of Aβ, other types of amyloids have been shown to associate with the vasculature. Interestingly, in many cases, vascular amyloidosis is accompanied by significant tau pathology. However, the contribution of tau to neurodegeneration associated to CAA remains to be determined. We used a mouse model of Familial Danish Dementia (FDD), a neurodegenerative disease characterized by the accumulation of Danish amyloid (ADan) in the vasculature, to characterize the contribution of tau to neurodegeneration associated to CAA. We performed histological and biochemical assays to establish tau modifications associated with CAA in conjunction with cell-based and electrophysiological assays to determine the role of tau in the synaptic dysfunction associated with ADan. We demonstrated that ADan aggregates induced hyperphosphorylation and misfolding of tau. Moreover, in a mouse model for CAA, we observed tau oligomers closely associated to astrocytes in the vicinity of vascular amyloid deposits. We finally determined that the absence of tau prevents synaptic dysfunction induced by ADan oligomers. In addition to demonstrating the effect of ADan amyloid on tau misfolding, our results provide compelling evidence of the role of tau in neurodegeneration associated with ADan-CAA and suggest that decreasing tau levels could be a feasible approach for the treatment of CAA.
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Ferrer I, García MA, González IL, Lucena DD, Villalonga AR, Tech MC, Llorens F, Garcia‐Esparcia P, Martinez‐Maldonado A, Mendez MF, Escribano BT, Bech‐Serra JJ, Sabido E, de la Torre Gómez C, del Rio JA. Aging-related tau astrogliopathy (ARTAG): not only tau phosphorylation in astrocytes. Brain Pathol 2018; 28:965-985. [PMID: 29396893 PMCID: PMC8028270 DOI: 10.1111/bpa.12593] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 01/26/2018] [Indexed: 12/12/2022] Open
Abstract
Aging-related tau astrogliopathy (ARTAG) is defined by the presence of two types of tau-bearing astrocytes: thorn-shaped astrocytes (TSAs) and granular/fuzzy astrocytes in the brain of old-aged individuals. The present study is focused on TSAs in rare forms of ARTAG with no neuronal tau pathology or restricted to entorhinal and transentorhinal cortices, to avoid bias from associated tauopathies. TSAs show 4Rtau phosphorylation at several specific sites and abnormal tau conformation, but they lack ubiquitin and they are not immunostained with tau-C3 antibodies which recognize truncated tau at Asp421. Astrocytes in ARTAG have atrophic processes, reduced glial fibrillary acidic protein (GFAP) and increased superoxide dismutase 2 (SOD2) immunoreactivity. Gel electrophoresis and western blotting of sarkosyl-insoluble fractions reveal a pattern of phospho-tau in ARTAG characterized by two bands of 68 and 64 kDa, and several middle bands between 35 and 50 kDa which differ from what is seen in AD. Phosphoproteomics of dissected vulnerable regions identifies an increase of phosphorylation marks in a large number of proteins in ARTAG compared with controls. GFAP, aquaporin 4, several serine-threonine kinases, microtubule associated proteins and other neuronal proteins are among the differentially phosphorylated proteins in ARTAG thus suggesting a hyper-phosphorylation background that affects several molecules, including many kinases and proteins from several cell compartments and various cell types. Finally, present results show for the first time that tau seeding is produced in neurons of the hippocampal complex, astrocytes, oligodendroglia and along fibers of the corpus callosum, fimbria and fornix following inoculation into the hippocampus of wild type mice of sarkosyl-insoluble fractions enriched in hyper-phosphorylated tau from selected ARTAG cases. These findings show astrocytes as crucial players of tau seeding in tauopathies.
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Affiliation(s)
- Isidro Ferrer
- Department of Pathology and Experimental TherapeuticsUniversity of BarcelonaBarcelonaSpain
- Bellvitge University Hospital, IDIBELL (Bellvitge Biomedical Research Centre)BarcelonaSpain
- Ministry of Economy and CompetitivenessCIBERNED (Network Centre of Biomedical Research of Neurodegenerative Diseases), Institute of Health Carlos IIIBarcelonaSpain
- Institute of Neurosciences, University of BarcelonaBarcelonaSpain
| | - Meritxell Aguiló García
- Department of Pathology and Experimental TherapeuticsUniversity of BarcelonaBarcelonaSpain
- Laboratory of Molecular Biology and BiochemistryInstitute for Molecular Biosciences, Karl‐Franzens University of GrazAustria
| | - Irene López González
- Ministry of Economy and CompetitivenessCIBERNED (Network Centre of Biomedical Research of Neurodegenerative Diseases), Institute of Health Carlos IIIBarcelonaSpain
| | - Daniela Diaz Lucena
- Ministry of Economy and CompetitivenessCIBERNED (Network Centre of Biomedical Research of Neurodegenerative Diseases), Institute of Health Carlos IIIBarcelonaSpain
| | - Aina Roig Villalonga
- Department of Pathology and Experimental TherapeuticsUniversity of BarcelonaBarcelonaSpain
| | - Margarita Carmona Tech
- Department of Pathology and Experimental TherapeuticsUniversity of BarcelonaBarcelonaSpain
- Ministry of Economy and CompetitivenessCIBERNED (Network Centre of Biomedical Research of Neurodegenerative Diseases), Institute of Health Carlos IIIBarcelonaSpain
| | - Franc Llorens
- Ministry of Economy and CompetitivenessCIBERNED (Network Centre of Biomedical Research of Neurodegenerative Diseases), Institute of Health Carlos IIIBarcelonaSpain
| | - Paula Garcia‐Esparcia
- Bellvitge University Hospital, IDIBELL (Bellvitge Biomedical Research Centre)BarcelonaSpain
| | | | - Margalida Frau Mendez
- Department of Pathology and Experimental TherapeuticsUniversity of BarcelonaBarcelonaSpain
| | - Benjamín Torrejón Escribano
- Biology Unit, Scientific and Technical ServicesUniversity of Barcelona, Hospitalet de LlobregatBarcelonaSpain
| | | | - Eduard Sabido
- Proteomics Unit, Centre de Regulació GenòmicaBarcelona Institute of Science and TechnologyBarcelonaSpain
| | | | - José Antonio del Rio
- Ministry of Economy and CompetitivenessCIBERNED (Network Centre of Biomedical Research of Neurodegenerative Diseases), Institute of Health Carlos IIIBarcelonaSpain
- Institute of Neurosciences, University of BarcelonaBarcelonaSpain
- Molecular and Cellular NeurobiotechnologyInstitute of Bioengineering of Catalonia (IBEC), Barcelona Institute for Science and Technology, Parc Científic de BarcelonaBarcelonaSpain
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Abstract
Astrocytes are involved in many diseases of the central nervous system, not only as reactive cells to neuronal damage but also as primary actors in the pathological process. Astrogliopathy is a term used to designate the involvement of astrocytes as key elements in the pathogenesis and pathology of diseases and injuries of the central nervous system. Astrocytopathy is utilized to name non-reactive astrogliosis covering hypertrophy, atrophy and astroglial degeneration with loss of function in astrocytes and pathological remodeling, as well as senescent changes. Astrogliopathy and astrocytopathy are hallmarks of tauopathies—neurodegenerative diseases with abnormal hyper-phosphorylated tau aggregates in neurons and glial cells. The involvement of astrocytes covers different disease-specific types such as tufted astrocytes, astrocytic plaques, thorn-shaped astrocytes, granular/fuzzy astrocytes, ramified astrocytes and astrocytes with globular inclusions, as well as others which are unnamed but not uncommon in familial frontotemporal degeneration linked to mutations in the tau gene. Knowledge of molecular differences among tau-containing astrocytes is only beginning, and their distinct functional implications remain rather poorly understood. However, tau-containing astrocytes in certain conditions have deleterious effects on neuronal function and nervous system integrity. Moreover, recent studies have shown that tau-containing astrocytes obtained from human brain tauopathies have a capacity for abnormal tau seeding and spreading in wild type mice. Inclusive conceptions include a complex scenario involving neurons, glial cells and local environmental factors that potentiate each other and promote disease progression in tauopathies.
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Javidnia M, Hebron ML, Xin Y, Kinney NG, Moussa CEH. Pazopanib Reduces Phosphorylated Tau Levels and Alters Astrocytes in a Mouse Model of Tauopathy. J Alzheimers Dis 2018; 60:461-481. [PMID: 28869476 DOI: 10.3233/jad-170429] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hyperphosphorylation and aggregation of tau protein is a critical factor in many neurodegenerative diseases. These diseases are increasing in prevalence, and there are currently no cures. Previous work from our group and others has shown that tyrosine kinase inhibitors (TKIs) can stimulate autophagy, decrease pathological proteins, and improve symptoms in models of neurodegeneration. Here we examined the role of pazopanib in mouse models that express either human mutant P301L tau (TauP301L) or triple mutant amyloid precursor protein (3x-AβPP). The TauP301L mouse expresses P301L tau under the control of a prion promoter in both neurons and astrocytes, reminiscent of some human tauopathies. Pazopanib crosses the blood-brain barrier with no detectable peripheral off-side effects, and decreases p-tau in TauP301L mice. Pazopanib reaches a brain concentration sufficient for inhibition of several tyrosine kinases, including vascular endothelial growth factor receptors (VEGFRs). Further, pazopanib does not affect microglia but reduces astrocyte levels toward nontransgenic controls in TauP301L mice. Pazopanib does not alter amyloid beta levels or astrocytes in 3x-AβPP mice but modulates a number of inflammatory markers (IP-10, MIP-1α, MIP-1β, and RANTES). These data suggest that pazopanib may be involved in p-tau clearance and modulation of astrocytic activity in models of tauopathies.
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Affiliation(s)
- Monica Javidnia
- Department of Neurology, Laboratory for Dementiaand Parkinsonism, Translational Neurotherapeutics Program, Washington, DC, USA.,Department of Pharmacologyand Physiology, Georgetown University Medical Center, Washington, DC, USA
| | - Michaeline L Hebron
- Department of Neurology, Laboratory for Dementiaand Parkinsonism, Translational Neurotherapeutics Program, Washington, DC, USA
| | - Yue Xin
- Department of Neurology, Laboratory for Dementiaand Parkinsonism, Translational Neurotherapeutics Program, Washington, DC, USA
| | - Nikolas G Kinney
- Department of Neurology, Laboratory for Dementiaand Parkinsonism, Translational Neurotherapeutics Program, Washington, DC, USA
| | - Charbel E-H Moussa
- Department of Neurology, Laboratory for Dementiaand Parkinsonism, Translational Neurotherapeutics Program, Washington, DC, USA
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Gorshkov K, Aguisanda F, Thorne N, Zheng W. Astrocytes as targets for drug discovery. Drug Discov Today 2018; 23:673-680. [PMID: 29317338 PMCID: PMC5937927 DOI: 10.1016/j.drudis.2018.01.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 11/08/2017] [Accepted: 01/04/2018] [Indexed: 12/18/2022]
Abstract
Recent studies have illuminated the crucial role of astrocytes in maintaining proper neuronal health and function. Abnormalities in astrocytic functions have now been implicated in the pathogenesis of neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS). Historically, drug development programs for neurodegenerative diseases generally target only neurons, overlooking the contributions of astrocytes. Therefore, targeting both disease neurons and astrocytes offers a new approach for drug development for the treatment of neurological diseases. Looking forward, the co-culturing of human neurons with astrocytes could be the next evolutionary step in drug discovery for neurodegenerative diseases.
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Affiliation(s)
- Kirill Gorshkov
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892, USA
| | - Francis Aguisanda
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892, USA
| | - Natasha Thorne
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wei Zheng
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892, USA.
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Sidoryk-Wegrzynowicz M, Gerber YN, Ries M, Sastre M, Tolkovsky AM, Spillantini MG. Astrocytes in mouse models of tauopathies acquire early deficits and lose neurosupportive functions. Acta Neuropathol Commun 2017; 5:89. [PMID: 29187256 PMCID: PMC6389177 DOI: 10.1186/s40478-017-0478-9] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 10/02/2017] [Indexed: 01/17/2023] Open
Abstract
Microtubule-associated protein tau aggregates constitute the characteristic neuropathological features of several neurodegenerative diseases grouped under the name of tauopathies. It is now clear that the process of tau aggregation is associated with neurodegeneration. Several transgenic tau mouse models have been developed where tau progressively aggregates, causing neuronal death. Previously we have shown that transplantation of astrocytes in P301S tau transgenic mice rescues cortical neuron death, implying that the endogenous astrocytes are deficient in survival support. We now show that the gliosis markers Glial fibrillary acidic protein (GFAP) and S100 calcium-binding protein B (S100β) are elevated in brains from P301S tau mice compared to control C57Bl/6 mice whereas the expression of proteins involved in glutamine/glutamate metabolism are reduced, pointing to a functional deficit. To test whether astrocytes from P301S mice are intrinsically deficient, we co-cultured astrocytes and neurons from control and P301S mice. Significantly more C57-derived and P301S-derived neurons survived when cells were cultured with C57-derived astrocytes or astrocyte conditioned medium (C57ACM) than with P301S-derived astrocytes or astrocyte conditioned medium (P301SACM), or ACM from P301L tau mice, where the transgene is also specifically expressed in neurons. The astrocytic alterations developed in mice during the first postnatal week of life. In addition, P301SACM significantly decreased presynaptic (synaptophysin, SNP) and postsynaptic (postsynaptic density protein 95, PSD95) protein expression in cortical neuron cultures whereas C57ACM enhanced these markers. Since thrombospondin 1 (TSP-1) is a major survival and synaptogenic factor, we examined whether TSP-1 is deficient in P301S mouse brains and ACM. Significantly less TSP-1 was expressed in the brains of P301S tau mice or produced by P301S-derived astrocytes, whereas supplementation of P301SACM with TSP-1 increased its neurosupportive capacity. Our results demonstrate that P301S-derived astrocytes acquire an early functional deficiency that may explain in part the loss of cortical neurons in the P301S tau mice.
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Kulbe JR, Hall ED. Chronic traumatic encephalopathy-integration of canonical traumatic brain injury secondary injury mechanisms with tau pathology. Prog Neurobiol 2017; 158:15-44. [PMID: 28851546 PMCID: PMC5671903 DOI: 10.1016/j.pneurobio.2017.08.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 08/09/2017] [Accepted: 08/17/2017] [Indexed: 12/14/2022]
Abstract
In recent years, a new neurodegenerative tauopathy labeled Chronic Traumatic Encephalopathy (CTE), has been identified that is believed to be primarily a sequela of repeated mild traumatic brain injury (TBI), often referred to as concussion, that occurs in athletes participating in contact sports (e.g. boxing, American football, Australian football, rugby, soccer, ice hockey) or in military combatants, especially after blast-induced injuries. Since the identification of CTE, and its neuropathological finding of deposits of hyperphosphorylated tau protein, mechanistic attention has been on lumping the disorder together with various other non-traumatic neurodegenerative tauopathies. Indeed, brains from suspected CTE cases that have come to autopsy have been confirmed to have deposits of hyperphosphorylated tau in locations that make its anatomical distribution distinct for other tauopathies. The fact that these individuals experienced repetitive TBI episodes during their athletic or military careers suggests that the secondary injury mechanisms that have been extensively characterized in acute TBI preclinical models, and in TBI patients, including glutamate excitotoxicity, intracellular calcium overload, mitochondrial dysfunction, free radical-induced oxidative damage and neuroinflammation, may contribute to the brain damage associated with CTE. Thus, the current review begins with an in depth analysis of what is known about the tau protein and its functions and dysfunctions followed by a discussion of the major TBI secondary injury mechanisms, and how the latter have been shown to contribute to tau pathology. The value of this review is that it might lead to improved neuroprotective strategies for either prophylactically attenuating the development of CTE or slowing its progression.
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Affiliation(s)
- Jacqueline R Kulbe
- Spinal Cord & Brain Injury Research Center, University of Kentucky College of Medicine, United States; Department of Neuroscience, University of Kentucky College of Medicine, United States
| | - Edward D Hall
- Spinal Cord & Brain Injury Research Center, University of Kentucky College of Medicine, United States; Department of Neuroscience, University of Kentucky College of Medicine, United States.
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Ferrer I. Diversity of astroglial responses across human neurodegenerative disorders and brain aging. Brain Pathol 2017; 27:645-674. [PMID: 28804999 PMCID: PMC8029391 DOI: 10.1111/bpa.12538] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 05/24/2017] [Indexed: 12/11/2022] Open
Abstract
Astrogliopathy refers to alterations of astrocytes occurring in diseases of the nervous system, and it implies the involvement of astrocytes as key elements in the pathogenesis and pathology of diseases and injuries of the central nervous system. Reactive astrocytosis refers to the response of astrocytes to different insults to the nervous system, whereas astrocytopathy indicates hypertrophy, atrophy/degeneration and loss of function and pathological remodeling occurring as a primary cause of a disease or as a factor contributing to the development and progression of a particular disease. Reactive astrocytosis secondary to neuron loss and astrocytopathy due to intrinsic alterations of astrocytes occur in neurodegenerative diseases, overlap each other, and, together with astrocyte senescence, contribute to disease-specific astrogliopathy in aging and neurodegenerative diseases with abnormal protein aggregates in old age. In addition to the well-known increase in glial fibrillary acidic protein and other proteins in reactive astrocytes, astrocytopathy is evidenced by deposition of abnormal proteins such as β-amyloid, hyper-phosphorylated tau, abnormal α-synuclein, mutated huntingtin, phosphorylated TDP-43 and mutated SOD1, and PrPres , in Alzheimer's disease, tauopathies, Lewy body diseases, Huntington's disease, amyotrophic lateral sclerosis and Creutzfeldt-Jakob disease, respectively. Astrocytopathy in these diseases can also be manifested by impaired glutamate transport; abnormal metabolism and release of neurotransmitters; altered potassium, calcium and water channels resulting in abnormal ion and water homeostasis; abnormal glucose metabolism; abnormal lipid and, particularly, cholesterol metabolism; increased oxidative damage and altered oxidative stress responses; increased production of cytokines and mediators of the inflammatory response; altered expression of connexins with deterioration of cell-to-cell networks and transfer of gliotransmitters; and worsening function of the blood brain barrier, among others. Increased knowledge of these aspects will permit a better understanding of brain aging and neurodegenerative diseases in old age as complex disorders in which neurons are not the only players.
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Affiliation(s)
- Isidro Ferrer
- Department of Pathology and Experimental TherapeuticsUniversity of BarcelonaBarcelonaSpain
- Institute of NeuropathologyPathologic Anatomy Service, Bellvitge University Hospital, IDIBELL, Hospitalet de LlobregatBarcelonaSpain
- Institute of NeurosciencesUniversity of BarcelonaBarcelonaSpain
- Biomedical Network Research Center on Neurodegenerative Diseases (CIBERNED), Institute Carlos IIIMadridSpain
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45
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Acosta C, Anderson HD, Anderson CM. Astrocyte dysfunction in Alzheimer disease. J Neurosci Res 2017; 95:2430-2447. [PMID: 28467650 DOI: 10.1002/jnr.24075] [Citation(s) in RCA: 161] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/07/2017] [Accepted: 04/10/2017] [Indexed: 12/11/2022]
Abstract
Astrocytes are glial cells that are distributed throughout the central nervous system in an arrangement optimal for chemical and physical interaction with neuronal synapses and brain blood supply vessels. Neurotransmission modulates astrocytic excitability by activating an array of cell surface receptors and transporter proteins, resulting in dynamic changes in intracellular Ca2+ or Na+ . Ionic and electrogenic astrocytic changes, in turn, drive vital cell nonautonomous effects supporting brain function, including regulation of synaptic activity, neuronal metabolism, and regional blood supply. Alzheimer disease (AD) is associated with aberrant oligomeric amyloid β generation, which leads to extensive proliferation of astrocytes with a reactive phenotype and abnormal regulation of these processes. Astrocytic morphology, Ca2+ responses, extracellular K+ removal, glutamate transport, amyloid clearance, and energy metabolism are all affected in AD, resulting in a deleterious set of effects that includes glutamate excitotoxicity, impaired synaptic plasticity, reduced carbon delivery to neurons for oxidative phosphorylation, and dysregulated linkages between neuronal energy demand and regional blood supply. This review summarizes how astrocytes are affected in AD and describes how these changes are likely to influence brain function. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Crystal Acosta
- Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada.,Canadian Centre for Agri-food Research in Health and Medicine, St. Boniface Hospital Research, Winnipeg, Manitoba, Canada
| | - Hope D Anderson
- Canadian Centre for Agri-food Research in Health and Medicine, St. Boniface Hospital Research, Winnipeg, Manitoba, Canada.,College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
| | - Christopher M Anderson
- Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada.,Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Manitoba, Canada
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Kilian JG, Hsu HW, Mata K, Wolf FW, Kitazawa M. Astrocyte transport of glutamate and neuronal activity reciprocally modulate tau pathology in Drosophila. Neuroscience 2017; 348:191-200. [PMID: 28215745 DOI: 10.1016/j.neuroscience.2017.02.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 02/01/2017] [Accepted: 02/07/2017] [Indexed: 01/21/2023]
Abstract
Abnormal buildup of the microtubule associated protein tau is a major pathological hallmark of Alzheimer's disease (AD) and various tauopathies. The mechanisms by which pathological tau accumulates and spreads throughout the brain remain largely unknown. Previously, we demonstrated that a restoration of the major astrocytic glutamate transporter, GLT1, ameliorated a buildup of tau pathology and rescued cognition in a mouse model of AD. We hypothesized that aberrant extracellular glutamate and abnormal neuronal excitatory activities promoted tau pathology. In the present study, we investigated genetic interactions between tau and the GLT1 homolog dEaat1 in Drosophila melanogaster. Neuronal-specific overexpression of human wildtype tau markedly shortened lifespan and impaired motor behavior. RNAi depletion of dEaat1 in astrocytes worsened these phenotypes, whereas overexpression of dEaat1 improved them. However, the synaptic neuropil appeared unaffected, and we failed to detect any major neuronal loss with tau overexpression in combination with dEaat1 depletion. To mimic glutamate-induced aberrant excitatory input in neurons, repeated depolarization of neurons via transgenic TrpA1 was applied to the adult Drosophila optic nerves, and we examined the change of tau deposits. Repeated depolarization significantly increased the accumulation of tau in these neurons. We propose that increased neuronal excitatory activity exacerbates tau-mediated neuronal toxicity and behavioral deficits.
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Affiliation(s)
- Jason G Kilian
- Center for Occupational and Environmental Health, Department of Medicine, University of California, Irvine, CA 92697, United States; Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, CA 95343, United States
| | - Heng-Wei Hsu
- Center for Occupational and Environmental Health, Department of Medicine, University of California, Irvine, CA 92697, United States; Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, CA 95343, United States
| | - Kenneth Mata
- Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, CA 95343, United States
| | - Fred W Wolf
- Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, CA 95343, United States
| | - Masashi Kitazawa
- Center for Occupational and Environmental Health, Department of Medicine, University of California, Irvine, CA 92697, United States; Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, CA 95343, United States.
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47
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Filous AR, Silver J. "Targeting astrocytes in CNS injury and disease: A translational research approach". Prog Neurobiol 2016; 144:173-87. [PMID: 27026202 PMCID: PMC5035184 DOI: 10.1016/j.pneurobio.2016.03.009] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 02/03/2016] [Accepted: 03/03/2016] [Indexed: 12/31/2022]
Abstract
Astrocytes are a major constituent of the central nervous system. These glia play a major role in regulating blood-brain barrier function, the formation and maintenance of synapses, glutamate uptake, and trophic support for surrounding neurons and glia. Therefore, maintaining the proper functioning of these cells is crucial to survival. Astrocyte defects are associated with a wide variety of neuropathological insults, ranging from neurodegenerative diseases to gliomas. Additionally, injury to the CNS causes drastic changes to astrocytes, often leading to a phenomenon known as reactive astrogliosis. This process is important for protecting the surrounding healthy tissue from the spread of injury, while it also inhibits axonal regeneration and plasticity. Here, we discuss the important roles of astrocytes after injury and in disease, as well as potential therapeutic approaches to restore proper astrocyte functioning.
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Affiliation(s)
- Angela R Filous
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 216-368-4615, United States.
| | - Jerry Silver
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 216-368-4615, United States.
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Arendt T, Stieler JT, Holzer M. Tau and tauopathies. Brain Res Bull 2016; 126:238-292. [DOI: 10.1016/j.brainresbull.2016.08.018] [Citation(s) in RCA: 333] [Impact Index Per Article: 41.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/31/2016] [Accepted: 08/31/2016] [Indexed: 12/11/2022]
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Bodea L, Eckert A, Ittner LM, Piguet O, Götz J. Tau physiology and pathomechanisms in frontotemporal lobar degeneration. J Neurochem 2016; 138 Suppl 1:71-94. [PMID: 27306859 PMCID: PMC5094566 DOI: 10.1111/jnc.13600] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 01/31/2016] [Accepted: 02/24/2016] [Indexed: 12/27/2022]
Abstract
Frontotemporal lobar degeneration (FTLD) has been associated with toxic intracellular aggregates of hyperphosphorylated tau (FTLD-tau). Moreover, genetic studies identified mutations in the MAPT gene encoding tau in familial cases of the disease. In this review, we cover a range of aspects of tau function, both in the healthy and diseased brain, discussing several in vitro and in vivo models. Tau structure and function in the healthy brain is presented, accentuating its distinct compartmentalization in neurons and its role in microtubule stabilization and axonal transport. Furthermore, tau-driven pathology is discussed, introducing current concepts and the underlying experimental evidence. Different aspects of pathological tau phosphorylation, the protein's genomic and domain organization as well as its spreading in disease, together with MAPT-associated mutations and their respective models are presented. Dysfunction related to other post-transcriptional modifications and their effect on normal neuronal functions such as cell cycle, epigenetics and synapse dynamics are also discussed, providing a mechanistic explanation for the observations made in FTLD-tau cases, with the possibility for therapeutic intervention. In this review, we cover aspects of tau function, both in the healthy and diseased brain, referring to different in vitro and in vivo models. In healthy neurons, tau is compartmentalized, with higher concentrations found in the distal part of the axon. Cargo molecules are sensitive to this gradient. A disturbed tau distribution, as found in frontotemporal lobar degeneration (FTLD-tau), has severe consequences for cellular physiology: tau accumulates in the neuronal soma and dendrites, leading among others to microtubule depolymerization and impaired axonal transport. Tau forms insoluble aggregates that sequester additional molecules stalling cellular physiology. Neuronal communication is gradually lost as toxic tau accumulates in dendritic spines with subsequent degeneration of synapses and synaptic loss. Thus, by providing a mechanistic explanation for the observations made in FTLD-tau cases, arises a possibility for therapeutic interventions. This article is part of the Frontotemporal Dementia special issue.
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Affiliation(s)
- Liviu‐Gabriel Bodea
- Clem Jones Centre for Ageing Dementia ResearchQueensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
| | - Anne Eckert
- Neurobiology LaboratoryPsychiatric University Clinics BaselUniversity of BaselBaselSwitzerland
| | - Lars Matthias Ittner
- Dementia Research UnitSchool of Medical SciencesFaculty of MedicineUniversity of New South WalesSydneyNSWAustralia
| | | | - Jürgen Götz
- Clem Jones Centre for Ageing Dementia ResearchQueensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
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Mungenast AE, Siegert S, Tsai LH. Modeling Alzheimer's disease with human induced pluripotent stem (iPS) cells. Mol Cell Neurosci 2016; 73:13-31. [PMID: 26657644 PMCID: PMC5930170 DOI: 10.1016/j.mcn.2015.11.010] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 11/05/2015] [Accepted: 11/25/2015] [Indexed: 02/08/2023] Open
Abstract
In the last decade, induced pluripotent stem (iPS) cells have revolutionized the utility of human in vitro models of neurological disease. The iPS-derived and differentiated cells allow researchers to study the impact of a distinct cell type in health and disease as well as performing therapeutic drug screens on a human genetic background. In particular, clinical trials for Alzheimer's disease (AD) have been failing. Two of the potential reasons are first, the species gap involved in proceeding from initial discoveries in rodent models to human studies, and second, an unsatisfying patient stratification, meaning subgrouping patients based on the disease severity due to the lack of phenotypic and genetic markers. iPS cells overcome this obstacles and will improve our understanding of disease subtypes in AD. They allow researchers conducting in depth characterization of neural cells from both familial and sporadic AD patients as well as preclinical screens on human cells. In this review, we briefly outline the status quo of iPS cell research in neurological diseases along with the general advantages and pitfalls of these models. We summarize how genome-editing techniques such as CRISPR/Cas9 will allow researchers to reduce the problem of genomic variability inherent to human studies, followed by recent iPS cell studies relevant to AD. We then focus on current techniques for the differentiation of iPS cells into neural cell types that are relevant to AD research. Finally, we discuss how the generation of three-dimensional cell culture systems will be important for understanding AD phenotypes in a complex cellular milieu, and how both two- and three-dimensional iPS cell models can provide platforms for drug discovery and translational studies into the treatment of AD.
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Affiliation(s)
- Alison E Mungenast
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Sandra Siegert
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA.
| | - Li-Huei Tsai
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
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