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León-Espinosa G, Antón-Fernández A, Tapia-González S, DeFelipe J, Muñoz A. Modifications of the axon initial segment during the hibernation of the Syrian hamster. Brain Struct Funct 2018; 223:4307-4321. [PMID: 30219944 DOI: 10.1007/s00429-018-1753-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 09/09/2018] [Indexed: 02/07/2023]
Abstract
Mammalian hibernation is a natural process in which the brain undergoes profound adaptive changes that appear to protect the brain from extreme hypoxia and hypothermia. In addition to a virtual cessation of neural and metabolic activity, these changes include a decrease in adult neurogenesis; the retraction of neuronal dendritic trees; changes in dendritic spines and synaptic connections; fragmentation of the Golgi apparatus; and the phosphorylation of the microtubule-associated protein tau. Furthermore, alterations of microglial cells also occur in torpor. Importantly, all of these changes are rapidly and fully reversed when the animals arouse from torpor state, with no apparent brain damage occurring. Thus, hibernating animals are excellent natural models to study different aspects of brain plasticity. The axon initial segment (AIS) is critical for the initiation of action potentials in neurons and is an efficient site for the regulation of neural activity. This specialized structure-characterized by the expression of different types of ion channels and adhesion, scaffolding and cytoskeleton proteins-is subjected to morpho-functional plastic changes upon variations in neural activity or in pathological conditions. Here, we used immunocytochemistry and 3D confocal microscopy reconstruction techniques to measure the possible morphological differences in the AIS of neocortical (layers II-III and V) and hippocampal (CA1) neurons during the hibernation of the Syrian hamster. Our results indicate that the general integrity of the AIS is resistant to the ischemia/hypoxia conditions that are characteristic of the torpor phase of hibernation. In addition, the length of the AIS significantly increased in all the regions studied-by about 16-20% in torpor animals compared to controls, suggesting the existence of compensatory mechanisms in response to a decrease in neuronal activity during the torpor phase of hibernation. Furthermore, in double-labeling experiment, we found that the AIS in layer V of torpid animals was longer in neurons expressing phospho-tau than in those not labeled for phospho-tau. This suggests that AIS plastic changes were more marked in phospho-tau accumulating neurons. Overall, the results further emphasize that mammalian hibernation is a good physiological model to study AIS plasticity mechanisms in non-pathological conditions.
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Affiliation(s)
- Gonzalo León-Espinosa
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain.,Facultad de Farmacia, Universidad San Pablo CEU, Madrid, Spain
| | - Alejandro Antón-Fernández
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain
| | - Silvia Tapia-González
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain
| | - Javier DeFelipe
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain.,CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Madrid, Spain
| | - Alberto Muñoz
- Instituto Cajal, CSIC, Madrid, Spain. .,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain. .,Departamento de Biología Celular, Universidad Complutense, Madrid, Spain.
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Antón-Fernández A, Merchán-Rubira J, Avila J, Hernández F, DeFelipe J, Muñoz A. Phospho-Tau Accumulation and Structural Alterations of the Golgi Apparatus of Cortical Pyramidal Neurons in the P301S Tauopathy Mouse Model. J Alzheimers Dis 2018; 60:651-661. [PMID: 28922155 PMCID: PMC5611801 DOI: 10.3233/jad-170332] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The Golgi apparatus (GA) is a highly dynamic organelle involved in the processing and sorting of cellular proteins. In Alzheimer’s disease (AD), it has been shown to decrease in size and become fragmented in neocortical and hippocampal neuronal subpopulations. This fragmentation and decrease in size of the GA in AD has been related to the accumulation of hyperphosphorylated tau. However, the involvement of other pathological factors associated with the course of the disease, such as the extracellular accumulation of amyloid-β (Aβ) aggregates, cannot be ruled out, since both pathologies are present in AD patients. Here we use the P301S tauopathy mouse model to examine possible alterations of the GA in neurons that overexpress human tau (P301S mutated gene) in neocortical and hippocampal neurons, using double immunofluorescence techniques and confocal microscopy. Quantitative analysis revealed that neurofibrillary tangle (NFT)-bearing neurons had important morphological alterations and reductions in the surface area and volume of the GA compared with NFT-free neurons. Since in this mouse model there are no Aβ aggregates typical of AD, the present findings support the idea that the progressive accumulation of phospho-tau is associated with structural alterations of the GA, and that these changes may occur in the absence of Aβ pathology.
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Affiliation(s)
- Alejandro Antón-Fernández
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Madrid, Spain
| | | | - Jesús Avila
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain.,CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Spain
| | - Félix Hernández
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain.,CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Spain
| | - Javier DeFelipe
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Madrid, Spain.,CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Spain
| | - Alberto Muñoz
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Madrid, Spain.,CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Spain.,Department of Cell Biology, Complutense University, Madrid, Spain
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Trzeciakiewicz H, Tseng JH, Wander CM, Madden V, Tripathy A, Yuan CX, Cohen TJ. A Dual Pathogenic Mechanism Links Tau Acetylation to Sporadic Tauopathy. Sci Rep 2017; 7:44102. [PMID: 28287136 PMCID: PMC5347034 DOI: 10.1038/srep44102] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 02/02/2017] [Indexed: 12/17/2022] Open
Abstract
Tau acetylation has recently emerged as a dominant post-translational modification (PTM) in Alzheimer’s disease (AD) and related tauopathies. Mass spectrometry studies indicate that tau acetylation sites cluster within the microtubule (MT)-binding region (MTBR), suggesting acetylation could regulate both normal and pathological tau functions. Here, we combined biochemical and cell-based approaches to uncover a dual pathogenic mechanism mediated by tau acetylation. We show that acetylation specifically at residues K280/K281 impairs tau-mediated MT stabilization, and enhances the formation of fibrillar tau aggregates, highlighting both loss and gain of tau function. Full-length acetylation-mimic tau showed increased propensity to undergo seed-dependent aggregation, revealing a potential role for tau acetylation in the propagation of tau pathology. We also demonstrate that methylene blue, a reported tau aggregation inhibitor, modulates tau acetylation, a novel mechanism of action for this class of compounds. Our study identifies a potential “two-hit” mechanism in which tau acetylation disengages tau from MTs and also promotes tau aggregation. Thus, therapeutic approaches to limit tau K280/K281 acetylation could simultaneously restore MT stability and ameliorate tau pathology in AD and related tauopathies.
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Affiliation(s)
- Hanna Trzeciakiewicz
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jui-Heng Tseng
- Department of Neurology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Connor M Wander
- Department of Neurology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Victoria Madden
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Ashutosh Tripathy
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Chao-Xing Yuan
- Alexion Pharmaceuticals Inc, New Haven, Connecticut 06510, USA
| | - Todd J Cohen
- Department of Neurology, UNC Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Tremblay C, François A, Delay C, Freland L, Vandal M, Bennett DA, Calon F. Association of Neuropathological Markers in the Parietal Cortex With Antemortem Cognitive Function in Persons With Mild Cognitive Impairment and Alzheimer Disease. J Neuropathol Exp Neurol 2017; 76:70-88. [PMID: 28158844 PMCID: PMC7526851 DOI: 10.1093/jnen/nlw109] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The associations between cognitive function and neuropathological markers in patients with mild cognitive impairment (MCI) and Alzheimer disease (AD) remain only partly defined. We investigated relationships between antemortem global cognitive scores and β-amyloid (Aβ), tau, TDP-43, synaptic proteins and other key AD neuropathological markers assessed by biochemical approaches in postmortem anterior parietal cortex samples from 36 subjects (12 MCI, 12 AD and 12 not cognitively impaired) from the Religious Orders Study. Overall, the strongest negative correlation coefficients associated with global cognitive scores were obtained for insoluble phosphorylated tau (r2 = -0.484), insoluble Aβ42 (r2 = -0.389) and neurofibrillary tangle counts (r2 = -0.494) (all p < 0.001). Robust inverse associations with cognition scores were also established for TDP-43-positive cytoplasmic inclusions (r2 = -0.476), total insoluble tau (r2 = -0.385) and Aβ plaque counts (r2 = -0.426). Sarkosyl (SK)- or formic acid (FA)-extracted tau showed similar interrelations. On the other hand, synaptophysin (r2 = +0.335), pS403/404 TDP-43 (r2 = +0.265) and septin-3 (r2 = +0.257) proteins positively correlated with cognitive scores. This study suggests that tau and Aβ42 in their insoluble aggregated forms, synaptic proteins and TDP-43 are the markers in the parietal cortex that are most strongly associated with cognitive function. This further substantiates the relevance of investigating these markers to understand the pathogenesis of AD and develop therapeutic tools.
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Affiliation(s)
- Cyntia Tremblay
- Faculté de pharmacie, Université Laval, Québec, QC, Canada
- Centre Hospitalier Universitaire de Québec (CHU-Q) Research Center, Neuroscience Axis, Québec, QC, Canada
| | - Arnaud François
- Faculté de pharmacie, Université Laval, Québec, QC, Canada
- Centre Hospitalier Universitaire de Québec (CHU-Q) Research Center, Neuroscience Axis, Québec, QC, Canada
| | - Charlotte Delay
- Facteurs de risque et déterminants moléculaires des maladies liées au vieillissement (RID-AGE) Research Group, University of Lille, INSERM U1167, Lille University Medical Center, Institut Pasteur de Lille, Lille, France (CD)
| | - Laure Freland
- Faculté de pharmacie, Université Laval, Québec, QC, Canada
- Centre Hospitalier Universitaire de Québec (CHU-Q) Research Center, Neuroscience Axis, Québec, QC, Canada
| | - Milène Vandal
- Faculté de pharmacie, Université Laval, Québec, QC, Canada
- Centre Hospitalier Universitaire de Québec (CHU-Q) Research Center, Neuroscience Axis, Québec, QC, Canada
| | - David A Bennett
- Rush Alzheimer’s Disease Center, Rush University Medical Center, Chicago, IL
| | - Frédéric Calon
- Faculté de pharmacie, Université Laval, Québec, QC, Canada
- Centre Hospitalier Universitaire de Québec (CHU-Q) Research Center, Neuroscience Axis, Québec, QC, Canada
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