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Cano-Astorga N, Plaza-Alonso S, Turegano-Lopez M, Rodrigo-Rodríguez J, Merchan-Perez A, DeFelipe J. Unambiguous identification of asymmetric and symmetric synapses using volume electron microscopy. Front Neuroanat 2024; 18:1348032. [PMID: 38645671 PMCID: PMC11026665 DOI: 10.3389/fnana.2024.1348032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 03/08/2024] [Indexed: 04/23/2024] Open
Abstract
The brain contains thousands of millions of synapses, exhibiting diverse structural, molecular, and functional characteristics. However, synapses can be classified into two primary morphological types: Gray's type I and type II, corresponding to Colonnier's asymmetric (AS) and symmetric (SS) synapses, respectively. AS and SS have a thick and thin postsynaptic density, respectively. In the cerebral cortex, since most AS are excitatory (glutamatergic), and SS are inhibitory (GABAergic), determining the distribution, size, density, and proportion of the two major cortical types of synapses is critical, not only to better understand synaptic organization in terms of connectivity, but also from a functional perspective. However, several technical challenges complicate the study of synapses. Potassium ferrocyanide has been utilized in recent volume electron microscope studies to enhance electron density in cellular membranes. However, identifying synaptic junctions, especially SS, becomes more challenging as the postsynaptic densities become thinner with increasing concentrations of potassium ferrocyanide. Here we describe a protocol employing Focused Ion Beam Milling and Scanning Electron Microscopy for studying brain tissue. The focus is on the unequivocal identification of AS and SS types. To validate SS observed using this protocol as GABAergic, experiments with immunocytochemistry for the vesicular GABA transporter were conducted on fixed mouse brain tissue sections. This material was processed with different concentrations of potassium ferrocyanide, aiming to determine its optimal concentration. We demonstrate that using a low concentration of potassium ferrocyanide (0.1%) improves membrane visualization while allowing unequivocal identification of synapses as AS or SS.
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Affiliation(s)
- Nicolás Cano-Astorga
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- PhD Program in Neuroscience, Autonoma de Madrid University-Cajal Institute, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Sergio Plaza-Alonso
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Marta Turegano-Lopez
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - José Rodrigo-Rodríguez
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Angel Merchan-Perez
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
- Departamento de Arquitectura y Tecnología de Sistemas Informáticos, Universidad Politécnica de Madrid, Madrid, Spain
| | - Javier DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
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Glausier JR, Bouchet-Marquis C, Maier M, Banks-Tibbs T, Wu K, Ning J, Melchitzky D, Lewis DA, Freyberg Z. Characterization of the three-dimensional synaptic and mitochondrial nanoarchitecture within glutamatergic synaptic complexes in postmortem human brain via focused ion beam-scanning electron microscopy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.26.582174. [PMID: 38463986 PMCID: PMC10925168 DOI: 10.1101/2024.02.26.582174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Glutamatergic synapses are the primary site of excitatory synaptic signaling and neural communication in the cerebral cortex. Electron microscopy (EM) studies in non-human model organisms have demonstrated that glutamate synaptic activity and functioning are directly reflected in quantifiable ultrastructural features. Thus, quantitative EM analysis of glutamate synapses in ex vivo preserved human brain tissue has the potential to provide novel insight into in vivo synaptic functioning. However, factors associated with the acquisition and preservation of human brain tissue have resulted in persistent concerns regarding the potential confounding effects of antemortem and postmortem biological processes on synaptic and sub-synaptic ultrastructural features. Thus, we sought to determine how well glutamate synaptic relationships and nanoarchitecture are preserved in postmortem human dorsolateral prefrontal cortex (DLPFC), a region that substantially differs in size and architecture from model systems. Focused ion beam-scanning electron microscopy (FIB-SEM), a powerful volume EM (VEM) approach, was employed to generate high-fidelity, fine-resolution, three-dimensional (3D) micrographic datasets appropriate for quantitative analyses. Using postmortem human DLPFC with a 6-hour postmortem interval, we optimized a tissue preservation and staining workflow that generated samples of excellent ultrastructural preservation and the high-contrast staining intensity required for FIB-SEM imaging. Quantitative analysis of sub-cellular, sub-synaptic and organelle components within glutamate axo-spinous synapses revealed that ultrastructural features of synaptic function and activity were well-preserved within and across individual synapses in postmortem human brain tissue. The synaptic, sub-synaptic and organelle measures were highly consistent with findings from experimental models that are free from antemortem or postmortem effects. Further, dense reconstruction of neuropil revealed a unique, ultrastructurally-complex, spiny dendritic shaft that exhibited features characteristic of neuronal processes with heightened synaptic communication, integration and plasticity. Altogether, our findings provide a critical proof-of-concept that ex vivo VEM analysis provides a valuable and informative means to infer in vivo functioning of human brain.
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Affiliation(s)
| | | | | | - Tabitha Banks-Tibbs
- Department of Psychiatry, University of Pittsburgh
- Department of Human Genetics, University of Pittsburgh
- College of Medicine, The Ohio State University
| | - Ken Wu
- Materials and Structural Analysis, Thermo Fisher Scientific
| | - Jiying Ning
- Department of Psychiatry, University of Pittsburgh
| | | | | | - Zachary Freyberg
- Department of Psychiatry, University of Pittsburgh
- Department of Cell Biology, University of Pittsburgh
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Woelfle S, Pedro MT, Wagner J, Schön M, Boeckers TM. Expression profiles of the autism-related SHANK proteins in the human brain. BMC Biol 2023; 21:254. [PMID: 37953224 PMCID: PMC10641957 DOI: 10.1186/s12915-023-01712-0] [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: 03/17/2023] [Accepted: 09/25/2023] [Indexed: 11/14/2023] Open
Abstract
BACKGROUND SHANKs are major scaffolding proteins at postsynaptic densities (PSDs) in the central nervous system. Mutations in all three family members have been associated with neurodevelopmental disorders such as autism spectrum disorders (ASDs). Despite the pathophysiological importance of SHANK2 and SHANK3 mutations in humans, research on the expression of these proteins is mostly based on rodent model organisms. RESULTS In the present study, cellular and neuropil SHANK2 expression was analyzed by immunofluorescence (IF) staining of post mortem human brain tissue from four male individuals (19 brain regions). Mouse brains were analyzed in comparison to evaluate the degree of phylogenetic conservation. Furthermore, SHANK2 and SHANK3 isoform patterns were compared in human and mouse brain lysates. While isoform expression and subcellular distribution were largely conserved, differences in neuropil levels of SHANK2 were found by IF staining: Maximum expression was concordantly measured in the cerebellum; however, higher SHANK2 expression was detected in the human brainstem and thalamus when compared to mice. One of the lowest SHANK2 levels was found in the human amygdala, a moderately expressing region in mouse. Quantification of SHANK3 IF in mouse brains unveiled a distribution comparable to humans. CONCLUSIONS In summary, these data show that the overall expression pattern of SHANK is largely conserved in defined brain regions; however, differences do exist, which need to be considered in the translation of rodent studies. The summarized expression patterns of SHANK2 and SHANK3 should serve as a reference for future studies.
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Affiliation(s)
- Sarah Woelfle
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Maria T Pedro
- Department of Neurosurgery, Ulm University, Campus Günzburg, Lindenallee 2, 89312, Günzburg, Germany
| | - Jan Wagner
- Department of Neurology, Ulm University and Universitäts- and Rehabilitationskliniken Ulm, 89081, Ulm, Germany
| | - Michael Schön
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
| | - Tobias M Boeckers
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
- Deutsches Zentrum Für Neurodegenerative Erkrankungen, DZNE, Ulm Site, 89081, Ulm, Germany.
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Guangming G, Mei C, Qinfeng Y, Xiang G, Chenchen Z, Qingyuan S, Wei X, Junhua G. Neurexin and neuroligins jointly regulate synaptic degeneration at the Drosophila neuromuscular junction based on TEM studies. Front Cell Neurosci 2023; 17:1257347. [PMID: 38026694 PMCID: PMC10646337 DOI: 10.3389/fncel.2023.1257347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 09/12/2023] [Indexed: 12/01/2023] Open
Abstract
The Drosophila larval neuromuscular junction (NMJ) is a well-known model system and is often used to study synapse development. Here, we show synaptic degeneration at NMJ boutons, primarily based on transmission electron microscopy (TEM) studies. When degeneration starts, the subsynaptic reticulum (SSR) swells, retracts and folds inward, and the residual SSR then degenerates into a disordered, thin or linear membrane. The axon terminal begins to degenerate from the central region, and the T-bar detaches from the presynaptic membrane with clustered synaptic vesicles to accelerate large-scale degeneration. There are two degeneration modes for clear synaptic vesicles. In the first mode, synaptic vesicles without actin filaments degenerate on the membrane with ultrafine spots and collapse and disperse to form an irregular profile with dark ultrafine particles. In the second mode, clear synaptic vesicles with actin filaments degenerate into dense synaptic vesicles, form irregular dark clumps without a membrane, and collapse and disperse to form an irregular profile with dark ultrafine particles. Last, all residual membranes in NMJ boutons degenerate into a linear shape, and all the residual elements in axon terminals degenerate and eventually form a cluster of dark ultrafine particles. Swelling and retraction of the SSR occurs prior to degradation of the axon terminal, which degenerates faster and with more intensity than the SSR. NMJ bouton degeneration occurs under normal physiological conditions but is accelerated in Drosophila neurexin (dnrx) dnrx273, Drosophila neuroligin (dnlg) dnlg1 and dnlg4 mutants and dnrx83;dnlg3 and dnlg2;dnlg3 double mutants, which suggests that both neurexin and neuroligins play a vital role in preventing synaptic degeneration.
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Affiliation(s)
- Gan Guangming
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Chen Mei
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Yu Qinfeng
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Gao Xiang
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Zhang Chenchen
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Sheng Qingyuan
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Xie Wei
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
- The Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, Jiangsu, China
| | - Geng Junhua
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
- Shenzhen Research Institute of Southeast University, Shenzhen, Guangdong, China
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5
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Taddei RN, Perbet R, Mate de Gerando A, Wiedmer AE, Sanchez-Mico M, Connors Stewart T, Gaona A, Melloni A, Amaral AC, Duff K, Frosch MP, Gómez-Isla T. Tau Oligomer-Containing Synapse Elimination by Microglia and Astrocytes in Alzheimer Disease. JAMA Neurol 2023; 80:1209-1221. [PMID: 37812432 PMCID: PMC10562992 DOI: 10.1001/jamaneurol.2023.3530] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 08/03/2023] [Indexed: 10/10/2023]
Abstract
Importance Factors associated with synapse loss beyond amyloid-β plaques and neurofibrillary tangles may more closely correlate with the emergence of cognitive deficits in Alzheimer disease (AD) and be relevant for early therapeutic intervention. Objective To investigate whether accumulation of tau oligomers in synapses is associated with excessive synapse elimination by microglia or astrocytes and with cognitive outcomes (dementia vs no dementia [hereinafter termed resilient]) of individuals with equal burdens of AD neuropathologic changes at autopsy. Design, Setting, and Participants This cross-sectional postmortem study included 40 human brains from the Massachusetts Alzheimer Disease Research Center Brain Bank with Braak III to IV stages of tau pathology but divergent antemortem cognition (dementia vs resilient) and cognitively normal controls with negligible AD neuropathologic changes. The visual cortex, a region without tau tangle deposition at Braak III to IV stages, was assessed after expansion microscopy to analyze spatial relationships of synapses with microglia and astrocytes. Participants were matched for age, sex, and apolipoprotein E status. Evidence of Lewy bodies, TDP-43 aggregates, or other lesions different from AD neuropathology were exclusion criteria. Tissue was collected from July 1998 to November 2020, and analyses were conducted from February 1, 2022, through May 31, 2023. Main Outcomes and Measures Amyloid-β plaques, tau neuropil thread burden, synapse density, tau oligomers in synapses, and internalization of tau oligomer-tagged synapses by microglia and astrocytes were quantitated. Analyses were performed using 1-way analysis of variance for parametric variables and the Kruskal-Wallis test for nonparametric variables; between-group differences were evaluated with Holm-Šídák tests. Results Of 40 included participants (mean [SD] age at death, 88 [8] years; 21 [52%] male), 19 had early-stage dementia with Braak stages III to IV, 13 had resilient brains with similar Braak stages III to IV, and 8 had no dementia (Braak stages 0-II). Brains with dementia but not resilient brains had substantial loss of presynaptic (43%), postsynaptic (33%), and colocalized mature synaptic elements (38%) compared with controls and significantly higher percentages of mature synapses internalized by IBA1-positive microglia (mean [SD], 13.3% [3.9%] in dementia vs 2.6% [1.9%] in resilient vs 0.9% [0.5%] in control; P < .001) and by GFAP-positive astrocytes (mean [SD], 17.2% [10.9%] in dementia vs 3.7% [4.0%] in resilient vs 2.7% [1.8%] in control; P = .001). In brains with dementia but not in resilient brains, tau oligomers more often colocalized with synapses, and the proportions of tau oligomer-containing synapses inside microglia (mean [SD] for presynapses, mean [SD], 7.4% [1.8%] in dementia vs 5.1% [1.9%] resilient vs 3.7% [0.8%] control; P = .006; and for postsynapses 11.6% [3.6%] dementia vs 6.8% [1.3%] resilient vs 7.4% [2.5%] control; P = .001) and astrocytes (mean [SD] for presynapses, 7.0% [2.1%] dementia vs 4.3% [2.2%] resilient vs 4.0% [0.7%] control; P = .001; and for postsynapses, 7.9% [2.2%] dementia vs 5.3% [1.8%] resilient vs 3.0% [1.5%] control; P < .001) were significantly increased compared with controls. Those changes in brains with dementia occurred in the absence of tau tangle deposition in visual cortex. Conclusion and Relevance The findings from this cross-sectional study suggest that microglia and astrocytes may excessively engulf synapses in brains of individuals with dementia and that the abnormal presence of tau oligomers in synapses may serve as signals for increased glial-mediated synapse elimination and early loss of brain function in AD.
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Affiliation(s)
- Raquel N. Taddei
- Neurology Department, Massachusetts General Hospital, Harvard University, Boston, Massachusetts
- Department of Neurology, Dementia Research Institute, University College London, United Kingdom
| | - Romain Perbet
- Neurology Department, Massachusetts General Hospital, Harvard University, Boston, Massachusetts
| | | | - Anne E. Wiedmer
- Neurology Department, Massachusetts General Hospital, Harvard University, Boston, Massachusetts
| | - Maria Sanchez-Mico
- Neurology Department, Massachusetts General Hospital, Harvard University, Boston, Massachusetts
| | - Theresa Connors Stewart
- C.S. Kubik Laboratory for Neuropathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Angelica Gaona
- C.S. Kubik Laboratory for Neuropathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Alexandra Melloni
- C.S. Kubik Laboratory for Neuropathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Ana C. Amaral
- Neurology Department, Massachusetts General Hospital, Harvard University, Boston, Massachusetts
| | - Karen Duff
- Department of Neurology, Dementia Research Institute, University College London, United Kingdom
| | - Matthew P. Frosch
- C.S. Kubik Laboratory for Neuropathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Teresa Gómez-Isla
- Neurology Department, Massachusetts General Hospital, Harvard University, Boston, Massachusetts
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Han X, Li PH, Wang S, Sanchez M, Aggarwal S, Blakely T, Schalek R, Meirovitch Y, Lin Z, Berger D, Wu Y, Aly F, Bay S, Delatour B, LaFaye P, Pfister H, Wei D, Jain V, Ploegh H, Lichtman J. A large-scale volumetric correlated light and electron microscopy study localizes Alzheimer's disease-related molecules in the hippocampus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.24.563674. [PMID: 37961104 PMCID: PMC10634883 DOI: 10.1101/2023.10.24.563674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Connectomics is a nascent neuroscience field to map and analyze neuronal networks. It provides a new way to investigate abnormalities in brain tissue, including in models of Alzheimer's disease (AD). This age-related disease is associated with alterations in amyloid-β (Aβ) and phosphorylated tau (pTau). These alterations correlate with AD's clinical manifestations, but causal links remain unclear. Therefore, studying these molecular alterations within the context of the local neuronal and glial milieu may provide insight into disease mechanisms. Volume electron microscopy (vEM) is an ideal tool for performing connectomics studies at the ultrastructural level, but localizing specific biomolecules within large-volume vEM data has been challenging. Here we report a volumetric correlated light and electron microscopy (vCLEM) approach using fluorescent nanobodies as immuno-probes to localize Alzheimer's disease-related molecules in a large vEM volume. Three molecules (pTau, Aβ, and a marker for activated microglia (CD11b)) were labeled without the need for detergents by three nanobody probes in a sample of the hippocampus of the 3xTg Alzheimer's disease model mouse. Confocal microscopy followed by vEM imaging of the same sample allowed for registration of the location of the molecules within the volume. This dataset revealed several ultrastructural abnormalities regarding the localizations of Aβ and pTau in novel locations. For example, two pTau-positive post-synaptic spine-like protrusions innervated by axon terminals were found projecting from the axon initial segment of a pyramidal cell. Three pyramidal neurons with intracellular Aβ or pTau were 3D reconstructed. Automatic synapse detection, which is necessary for connectomics analysis, revealed the changes in density and volume of synapses at different distances from an Aβ plaque. This vCLEM approach is useful to uncover molecular alterations within large-scale volume electron microscopy data, opening a new connectomics pathway to study Alzheimer's disease and other types of dementia.
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Zhu M, Xiao B, Xue T, Qin S, Ding J, Wu Y, Tang Q, Huang M, Zhao N, Ye Y, Zhang Y, Zhang B, Li J, Guo F, Jiang Y, Zhang L, Zhang L. Cdc42GAP deficiency contributes to the Alzheimer's disease phenotype. Brain 2023; 146:4350-4365. [PMID: 37254741 DOI: 10.1093/brain/awad184] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 04/20/2023] [Accepted: 05/05/2023] [Indexed: 06/01/2023] Open
Abstract
Alzheimer's disease, the most common cause of dementia, is a chronic degenerative disease with typical pathological features of extracellular senile plaques and intracellular neurofibrillary tangles and a significant decrease in the density of neuronal dendritic spines. Cdc42 is a member of the small G protein family that plays an important role in regulating synaptic plasticity and is regulated by Cdc42GAP, which switches Cdc42 from active GTP-bound to inactive GDP-bound states regulating downstream pathways via effector proteins. However, few studies have focused on Cdc42 in the progression of Alzheimer's disease. In a heterozygous Cdc42GAP mouse model that exhibited elevated Cdc42-GTPase activity accompanied by increased Cdc42-PAK1-cofilin signalling, we found impairments in cognitive behaviours, neuron senescence, synaptic loss with depolymerization of F-actin and the pathological phenotypes of Alzheimer's disease, including phosphorylated tau (p-T231, AT8), along with increased soluble and insoluble Aβ1-42 and Aβ1-40, which are consistent with typical Alzheimer's disease mice. Interestingly, these impairments increased significantly with age. Furthermore, the results of quantitative phosphoproteomic analysis of the hippocampus of 11-month-old GAP mice suggested that Cdc42GAP deficiency induces and accelerates Alzheimer's disease-like phenotypes through activation of GSK-3β by dephosphorylation at Ser9, Ser389 and/or phosphorylation at Tyr216. In addition, overexpression of dominant-negative Cdc42 in the primary hippocampal and cortical neurons of heterozygous Cdc42GAP mice reversed synaptic loss and tau hyperphosphorylation. Importantly, the Cdc42 signalling pathway, Aβ1-42, Aβ1-40 and GSK-3β activity were increased in the cortical sections of Alzheimer's disease patients compared with those in healthy controls. Together, these data indicated that Cdc42GAP is involved in regulating Alzheimer's disease-like phenotypes such as cognitive deficits, dendritic spine loss, phosphorylated tau (p-T231, AT8) and increased soluble and insoluble Aβ1-42 and Aβ1-40, possibly through the activation of GSK-3β, and these impairments increased significantly with age. Thus, we provide the first evidence that Cdc42 is involved in the progression of Alzheimer's disease-like phenotypes, which may provide new targets for Alzheimer's disease treatment.
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Affiliation(s)
- Mengjuan Zhu
- Guangdong Provincial Key Laboratory of Functional Proteomics, Key Laboratory of Mental Health of the Ministry of Education, School of Basic Medical Sciences, Department of Otorhinolaryngology-Head and Neck Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
| | - Bin Xiao
- Guangdong Provincial Key Laboratory of Functional Proteomics, Key Laboratory of Mental Health of the Ministry of Education, School of Basic Medical Sciences, Department of Otorhinolaryngology-Head and Neck Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
| | - Tao Xue
- Guangdong Provincial Key Laboratory of Functional Proteomics, Key Laboratory of Mental Health of the Ministry of Education, School of Basic Medical Sciences, Department of Otorhinolaryngology-Head and Neck Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
| | - Sifei Qin
- Guangdong Provincial Key Laboratory of Functional Proteomics, Key Laboratory of Mental Health of the Ministry of Education, School of Basic Medical Sciences, Department of Otorhinolaryngology-Head and Neck Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
| | - Jiuyang Ding
- School of Forensic Medicine, Guizhou Medical University, Guiyang 550004, China
| | - Yue Wu
- Guangdong Provincial Key Laboratory of Functional Proteomics, Key Laboratory of Mental Health of the Ministry of Education, School of Basic Medical Sciences, Department of Otorhinolaryngology-Head and Neck Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
| | - Qingqiu Tang
- Guangdong Provincial Key Laboratory of Functional Proteomics, Key Laboratory of Mental Health of the Ministry of Education, School of Basic Medical Sciences, Department of Otorhinolaryngology-Head and Neck Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
| | - Mengfan Huang
- Guangdong Provincial Key Laboratory of Functional Proteomics, Key Laboratory of Mental Health of the Ministry of Education, School of Basic Medical Sciences, Department of Otorhinolaryngology-Head and Neck Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
| | - Na Zhao
- School of Forensic Medicine, Guizhou Medical University, Guiyang 550004, China
| | - Yingshan Ye
- Guangdong Provincial Key Laboratory of Functional Proteomics, Key Laboratory of Mental Health of the Ministry of Education, School of Basic Medical Sciences, Department of Otorhinolaryngology-Head and Neck Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
| | - Yuning Zhang
- Guangdong Provincial Key Laboratory of Functional Proteomics, Key Laboratory of Mental Health of the Ministry of Education, School of Basic Medical Sciences, Department of Otorhinolaryngology-Head and Neck Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
| | - Boya Zhang
- Guangdong Provincial Key Laboratory of Functional Proteomics, Key Laboratory of Mental Health of the Ministry of Education, School of Basic Medical Sciences, Department of Otorhinolaryngology-Head and Neck Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
| | - Juan Li
- Department of Histology and Embryology, NMPA Key Laboratory for Safety Evaluation of Cosmetics, Guangdong Provincial Key Laboratory of Construction and Detection in Tissue Engineering, School of Basic Medical Sciences, Center for Orthopedic Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
| | - Fukun Guo
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Research Foundation, Cincinnati, OH 45229-3026, USA
| | - Yong Jiang
- Guangdong Provincial Key Laboratory of Functional Proteomics, Key Laboratory of Mental Health of the Ministry of Education, School of Basic Medical Sciences, Department of Otorhinolaryngology-Head and Neck Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
| | - Lin Zhang
- Department of Histology and Embryology, NMPA Key Laboratory for Safety Evaluation of Cosmetics, Guangdong Provincial Key Laboratory of Construction and Detection in Tissue Engineering, School of Basic Medical Sciences, Center for Orthopedic Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
| | - Lu Zhang
- Guangdong Provincial Key Laboratory of Functional Proteomics, Key Laboratory of Mental Health of the Ministry of Education, School of Basic Medical Sciences, Department of Otorhinolaryngology-Head and Neck Surgery of the Third Affiliated Hospital, Southern Medical University, Guangzhou 510515, China
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8
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Cano-Astorga N, Plaza-Alonso S, DeFelipe J, Alonso-Nanclares L. 3D synaptic organization of layer III of the human anterior cingulate and temporopolar cortex. Cereb Cortex 2023; 33:9691-9708. [PMID: 37455478 PMCID: PMC10472499 DOI: 10.1093/cercor/bhad232] [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: 04/11/2023] [Revised: 06/08/2023] [Accepted: 06/09/2023] [Indexed: 07/18/2023] Open
Abstract
The human anterior cingulate and temporopolar cortices have been proposed as highly connected nodes involved in high-order cognitive functions, but their synaptic organization is still basically unknown due to the difficulties involved in studying the human brain. Using Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM) to study the synaptic organization of the human brain obtained with a short post-mortem delay allows excellent results to be obtained. We have used this technology to analyze layer III of the anterior cingulate cortex (Brodmann area 24) and the temporopolar cortex, including the temporal pole (Brodmann area 38 ventral and dorsal) and anterior middle temporal gyrus (Brodmann area 21). Our results, based on 6695 synaptic junctions fully reconstructed in 3D, revealed that Brodmann areas 24, 21 and ventral area 38 showed similar synaptic density and synaptic size, whereas dorsal area 38 displayed the highest synaptic density and the smallest synaptic size. However, the proportion of the different types of synapses (excitatory and inhibitory), the postsynaptic targets, and the shapes of excitatory and inhibitory synapses were similar, regardless of the region examined. These observations indicate that certain aspects of the synaptic organization are rather homogeneous, whereas others show specific variations across cortical regions.
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Affiliation(s)
- Nicolás Cano-Astorga
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223 Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Doctor Arce 37, 28002 Madrid, Spain
- PhD Program in Neuroscience, Autonoma de Madrid University - Cajal Institute, 28029 Madrid, Spain
| | - Sergio Plaza-Alonso
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223 Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Doctor Arce 37, 28002 Madrid, Spain
| | - Javier DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223 Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Doctor Arce 37, 28002 Madrid, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Valderrebollo 5, 28031 Madrid, Spain
| | - Lidia Alonso-Nanclares
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223 Madrid, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Doctor Arce 37, 28002 Madrid, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Valderrebollo 5, 28031 Madrid, Spain
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9
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Melgosa-Ecenarro L, Doostdar N, Radulescu CI, Jackson JS, Barnes SJ. Pinpointing the locus of GABAergic vulnerability in Alzheimer's disease. Semin Cell Dev Biol 2023; 139:35-54. [PMID: 35963663 DOI: 10.1016/j.semcdb.2022.06.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 06/30/2022] [Accepted: 06/30/2022] [Indexed: 12/31/2022]
Abstract
The early stages of Alzheimer's disease (AD) have been linked to microcircuit dysfunction and pathophysiological neuronal firing in several brain regions. Inhibitory GABAergic microcircuitry is a critical feature of stable neural-circuit function in the healthy brain, and its dysregulation has therefore been proposed as contributing to AD-related pathophysiology. However, exactly how the critical balance between excitatory and inhibitory microcircuitry is modified by AD pathogenesis remains unclear. Here, we set the current evidence implicating dysfunctional GABAergic microcircuitry as a driver of early AD pathophysiology in a simple conceptual framework. Our framework is based on a generalised reductionist model of firing-rate control by local feedback inhibition. We use this framework to consider multiple loci that may be vulnerable to disruption by AD pathogenesis. We first start with evidence investigating how AD-related processes may impact the gross number of inhibitory neurons in the network. We then move to discuss how pathology may impact intrinsic cellular properties and firing thresholds of GABAergic neurons. Finally, we cover how AD-related pathogenesis may disrupt synaptic connectivity between excitatory and inhibitory neurons. We use the feedback inhibition framework to discuss and organise the available evidence from both preclinical rodent work and human studies in AD patients and conclude by identifying key questions and understudied areas for future investigation.
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Affiliation(s)
- Leire Melgosa-Ecenarro
- UK Dementia Research Institute, Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
| | - Nazanin Doostdar
- UK Dementia Research Institute, Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
| | - Carola I Radulescu
- UK Dementia Research Institute, Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
| | - Johanna S Jackson
- UK Dementia Research Institute, Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
| | - Samuel J Barnes
- UK Dementia Research Institute, Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.
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10
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Wang W, Zhao F, Lu Y, Siedlak SL, Fujioka H, Feng H, Perry G, Zhu X. Damaged mitochondria coincide with presynaptic vesicle loss and abnormalities in alzheimer's disease brain. Acta Neuropathol Commun 2023; 11:54. [PMID: 37004141 PMCID: PMC10067183 DOI: 10.1186/s40478-023-01552-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 03/16/2023] [Indexed: 04/03/2023] Open
Abstract
Loss of synapses is the most robust pathological correlate of Alzheimer's disease (AD)-associated cognitive deficits, although the underlying mechanism remains incompletely understood. Synaptic terminals have abundant mitochondria which play an indispensable role in synaptic function through ATP provision and calcium buffering. Mitochondrial dysfunction is an early and prominent feature in AD which could contribute to synaptic deficits. Here, using electron microscopy, we examined synapses with a focus on mitochondrial deficits in presynaptic axonal terminals and dendritic spines in cortical biopsy samples from clinically diagnosed AD and age-matched non-AD control patients. Synaptic vesicle density within the presynaptic axon terminals was significantly decreased in AD cases which appeared largely due to significantly decreased reserve pool, but there were significantly more presynaptic axons containing enlarged synaptic vesicles or dense core vesicles in AD. Importantly, there was reduced number of mitochondria along with significantly increased damaged mitochondria in the presynapse of AD which correlated with changes in SV density. Mitochondria in the post-synaptic dendritic spines were also enlarged and damaged in the AD biopsy samples. This study provided evidence of presynaptic vesicle loss as synaptic deficits in AD and suggested that mitochondrial dysfunction in both pre- and post-synaptic compartments contribute to synaptic deficits in AD.
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Affiliation(s)
- Wenzhang Wang
- Department of Pathology, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH, 44106, USA
| | - Fanpeng Zhao
- Department of Pathology, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH, 44106, USA
| | - Yubing Lu
- Department of Pathology, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH, 44106, USA
| | - Sandra L Siedlak
- Department of Pathology, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH, 44106, USA
| | - Hisashi Fujioka
- Cryo-EM Core Facility, Case Western Reserve University, Cleveland, OH, USA
| | - Hao Feng
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH, USA
| | - George Perry
- Department of Neuroscience, Developmental and Regenerative Biology, University of Texas, San Antonio, TX, USA
| | - Xiongwei Zhu
- Department of Pathology, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH, 44106, USA.
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11
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Lukacs IP, Francavilla R, Field M, Hunter E, Howarth M, Horie S, Plaha P, Stacey R, Livermore L, Ansorge O, Tamas G, Somogyi P. Differential effects of group III metabotropic glutamate receptors on spontaneous inhibitory synaptic currents in spine-innervating double bouquet and parvalbumin-expressing dendrite-targeting GABAergic interneurons in human neocortex. Cereb Cortex 2023; 33:2101-2142. [PMID: 35667019 PMCID: PMC9977385 DOI: 10.1093/cercor/bhac195] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 11/12/2022] Open
Abstract
Diverse neocortical GABAergic neurons specialize in synaptic targeting and their effects are modulated by presynaptic metabotropic glutamate receptors (mGluRs) suppressing neurotransmitter release in rodents, but their effects in human neocortex are unknown. We tested whether activation of group III mGluRs by L-AP4 changes GABAA receptor-mediated spontaneous inhibitory postsynaptic currents (sIPSCs) in 2 distinct dendritic spine-innervating GABAergic interneurons recorded in vitro in human neocortex. Calbindin-positive double bouquet cells (DBCs) had columnar "horsetail" axons descending through layers II-V innervating dendritic spines (48%) and shafts, but not somata of pyramidal and nonpyramidal neurons. Parvalbumin-expressing dendrite-targeting cell (PV-DTC) axons extended in all directions innervating dendritic spines (22%), shafts (65%), and somata (13%). As measured, 20% of GABAergic neuropil synapses innervate spines, hence DBCs, but not PV-DTCs, preferentially select spine targets. Group III mGluR activation paradoxically increased the frequency of sIPSCs in DBCs (to median 137% of baseline) but suppressed it in PV-DTCs (median 92%), leaving the amplitude unchanged. The facilitation of sIPSCs in DBCs may result from their unique GABAergic input being disinhibited via network effect. We conclude that dendritic spines receive specialized, diverse GABAergic inputs, and group III mGluRs differentially regulate GABAergic synaptic transmission to distinct GABAergic cell types in human cortex.
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Affiliation(s)
- Istvan P Lukacs
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
| | | | - Martin Field
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
| | - Emily Hunter
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
| | - Michael Howarth
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
| | - Sawa Horie
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
| | - Puneet Plaha
- Department of Neurosurgery, John Radcliffe Hospital, OUH NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Richard Stacey
- Department of Neurosurgery, John Radcliffe Hospital, OUH NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Laurent Livermore
- Department of Neurosurgery, John Radcliffe Hospital, OUH NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Olaf Ansorge
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Gabor Tamas
- Department of Physiology, Anatomy and Neuroscience, University of Szeged, 6726 Szeged, Hungary
| | - Peter Somogyi
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
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12
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Lin NH, Goh A, Lin SH, Chuang KA, Chang CH, Li MH, Lu CH, Chen WY, Wei PH, Pan IH, Perng MD, Wen SF. Neuroprotective Effects of a Multi-Herbal Extract on Axonal and Synaptic Disruption in Vitro and Cognitive Impairment in Vivo. J Alzheimers Dis Rep 2023; 7:51-76. [PMID: 36777330 PMCID: PMC9912829 DOI: 10.3233/adr-220056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 01/02/2023] [Indexed: 01/19/2023] Open
Abstract
Background Alzheimer's disease (AD) is a multifactorial disorder characterized by cognitive decline. Current available therapeutics for AD have limited clinical benefit. Therefore, preventive therapies for interrupting the development of AD are critically needed. Molecules targeting multifunction to interact with various pathlogical components have been considered to improve the therapeutic efficiency of AD. In particular, herbal medicines with multiplicity of actions produce cognitive benefits on AD. Bugu-M is a multi-herbal extract composed of Ganoderma lucidum (Antler form), Nelumbo nucifera Gaertn., Ziziphus jujuba Mill., and Dimocarpus longan, with the ability of its various components to confer resilience to cognitive deficits. Objective To evaluate the potential of Bugu-M on amyloid-β (Aβ) toxicity and its in vitro mechanisms and on in vivo cognitive function. Methods We illustrated the effect of Bugu-M on Aβ25-35-evoked toxicity as well as its possible mechanisms to diminish the pathogenesis of AD in rat cortical neurons. For cognitive function studies, 2-month-old female 3×Tg-AD mice were administered 400 mg/kg Bugu-M for 30 days. Behavioral tests were performed to assess the efficacy of Bugu-M on cognitive impairment. Results In primary cortical neuronal cultures, Bugu-M mitigated Aβ-evoked toxicity by reducing cytoskeletal aberrations and axonal disruption, restoring presynaptic and postsynaptic protein expression, suppressing mitochondrial damage and apoptotic signaling, and reserving neurogenic and neurotrophic factors. Importantly, 30-day administration of Bugu-M effectively prevented development of cognitive impairment in 3-month-old female 3×Tg-AD mice. Conclusion Bugu-M might be beneficial in delaying the progression of AD, and thus warrants consideration for its preventive potential for AD.
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Affiliation(s)
- Ni-Hsuan Lin
- Institute of Molecular Medicine, College of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan
| | - Angela Goh
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Shyh-Horng Lin
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Kai-An Chuang
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Chih-Hsuan Chang
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Ming-Han Li
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Chu-Hsun Lu
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Wen-Yin Chen
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Pei-Hsuan Wei
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - I-Hong Pan
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Ming-Der Perng
- Institute of Molecular Medicine, College of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan,
School of Medicine, College of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan,Correspondence to: Shu-Fang Wen, Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, 321, Section 2, Kuang-Fu Road, Hsinchu 300044, Taiwan. Tel.: +886 35743946; E-mail: and Ming-Der Perng, College of Life Sciences, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 300044, Taiwan. Tel.: +886 35742024; E-mail:
| | - Shu-Fang Wen
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan,Correspondence to: Shu-Fang Wen, Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, 321, Section 2, Kuang-Fu Road, Hsinchu 300044, Taiwan. Tel.: +886 35743946; E-mail: and Ming-Der Perng, College of Life Sciences, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 300044, Taiwan. Tel.: +886 35742024; E-mail:
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13
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Weible AP, Wehr M. Amyloid Pathology in the Central Auditory Pathway of 5XFAD Mice Appears First in Auditory Cortex. J Alzheimers Dis 2022; 89:1385-1402. [PMID: 36031901 PMCID: PMC10097438 DOI: 10.3233/jad-220538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Background: Effective treatment of Alzheimer’s disease (AD) will hinge on early detection. This has led to the search for early biomarkers that use non-invasive testing. One possible early biomarker is auditory temporal processing deficits, which reflect central auditory pathway dysfunction and precede cognitive and memory declines in AD. Gap detection is a measure of auditory temporal processing, is impaired in human AD, and is also impaired in the 5XFAD mouse model of AD. Gap detection deficits appear as early as postnatal day 60 in 5XFAD mice, months before cognitive deficits or cell death, supporting gap detection as an early biomarker. However, it remains unclear how gap detection deficits relate to the progression of amyloid pathology in the auditory system. Objective: To determine the progression of amyloid pathology throughout the central auditory system and across age in 5XFAD mice. Methods: We quantified intracellular and extracellular antibody labelling of Aβ 42 in 6 regions of the central auditory system from p14 to p150. Results: Pathology appeared first in primary auditory cortex (A1) as intracellular accumulation of Aβ 42 in layer 5 pyramidal neurons by age p21. Extracellular plaques appeared later, by age p90, in A1, medial geniculate body, and inferior colliculus. Auditory brainstem structures showed minimal amyloid pathology. We also observed pathology in the caudal pontine reticular nucleus, a brainstem structure that is outside of the central auditory pathway but which is involved in the acoustic startle reflex. Conclusion: These results suggest that Aβ 42 accumulation, but not plaques, may impair gap detection.
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Affiliation(s)
- Aldis P. Weible
- Department of Psychology, Institute of Neuroscience, University of Oregon, Eugene, OR, USA
| | - Michael Wehr
- Department of Psychology, Institute of Neuroscience, University of Oregon, Eugene, OR, USA
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14
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Martínez-Serra R, Alonso-Nanclares L, Cho K, Giese KP. Emerging insights into synapse dysregulation in Alzheimer's disease. Brain Commun 2022; 4:fcac083. [PMID: 35652120 PMCID: PMC9149787 DOI: 10.1093/braincomms/fcac083] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 02/15/2022] [Accepted: 04/05/2022] [Indexed: 11/14/2022] Open
Abstract
Alzheimer's disease is the leading cause of dementia and a growing worldwide problem, with its incidence expected to increase in the coming years. Since synapse loss is a major pathology and is correlated with symptoms in Alzheimer's disease, synapse dysfunction and loss may underlie pathophysiology. In this context, this review focuses on emerging insights into synaptic changes at the ultrastructural level. The three-dimensional electron microscopy technique unequivocally detects all types of synapses, including multi-synapses, which are indicators of synaptic connectivity between neurons. In recent years it has become feasible to perform sophisticated three-dimensional electron microscopy analyses on post-mortem human Alzheimer's disease brain as tissue preservation and electron microscopy techniques have improved. This ultrastructural analysis found that synapse loss does not always precede neuronal loss, as long believed. For instance, in the transentorhinal cortex and area CA1 of the hippocampus, synapse loss does not precede neuronal loss. However, in the entorhinal cortex, synapse loss precedes neuronal loss. Moreover, the ultrastructural analysis provides details about synapse morphology. For example, changes in excitatory synapses' post-synaptic densities, with fragmented postsynaptic densities increasing at the expense of perforated synapses, are seen in Alzheimer's disease brain. Further, multi-synapses also appear to be altered in Alzheimer's disease by doubling the abundance of multi-innervated spines in the transentorhinal cortex of Alzheimer's disease brain. Collectively, these recent ultrastructural analyses highlight distinct synaptic phenotypes in different Alzheimer's disease brain regions and broaden the understanding of synapse alterations, which may unravel some new therapeutic targets.
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Affiliation(s)
- Raquel Martínez-Serra
- Department of Basic and Clinical Neuroscience,
Institute of Psychiatry, Psychology and Neuroscience, King’s College
London, London SE5 9NU, UK
| | - Lidia Alonso-Nanclares
- Instituto Cajal (CSIC - Consejo Superior de
Investigaciones Científicas), Avda. Doctor Arce 37, 28002
Madrid, Spain
- Laboratorio Cajal de Circuitos Corticales (CTB),
Universidad Politécnica de Madrid, Campus de Montegancedo
s/n, Pozuelo de Alarcón 28223, Madrid, Spain
| | - Kwangwook Cho
- Department of Basic and Clinical Neuroscience,
Institute of Psychiatry, Psychology and Neuroscience, King’s College
London, London SE5 9NU, UK
- UK-Dementia Research Institute at King’s
College London, London SE5 9NU, UK
| | - K. Peter Giese
- Department of Basic and Clinical Neuroscience,
Institute of Psychiatry, Psychology and Neuroscience, King’s College
London, London SE5 9NU, UK
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15
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Trujillo-Estrada L, Vanderklish PW, Nguyen MMT, Kuang RR, Nguyen C, Huynh E, da Cunha C, Javonillo DI, Forner S, Martini AC, Sarraf ST, Simmon VF, Baglietto-Vargas D, LaFerla FM. SPG302 Reverses Synaptic and Cognitive Deficits Without Altering Amyloid or Tau Pathology in a Transgenic Model of Alzheimer's Disease. Neurotherapeutics 2021; 18:2468-2483. [PMID: 34738197 PMCID: PMC8804111 DOI: 10.1007/s13311-021-01143-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2021] [Indexed: 12/04/2022] Open
Abstract
Alzheimer's disease (AD) is conceptualized as a synaptic failure disorder in which loss of glutamatergic synapses is a major driver of cognitive decline. Thus, novel therapeutic strategies aimed at regenerating synapses may represent a promising approach to mitigate cognitive deficits in AD patients. At present, no disease-modifying drugs exist for AD, and approved therapies are palliative at best, lacking in the ability to reverse the synaptic failure. Here, we tested the efficacy of a novel synaptogenic small molecule, SPG302 - a 3rd-generation benzothiazole derivative that increases the density of axospinous glutamatergic synapses - in 3xTg-AD mice. Daily dosing of 3xTg-AD mice with SPG302 at 3 and 30 mg/kg (i.p.) for 4 weeks restored hippocampal synaptic density and improved cognitive function in hippocampal-dependent tasks. Mushroom and stubby spine profiles were increased by SPG302, and associated with enhanced expression of key postsynaptic proteins - including postsynaptic density protein 95 (PSD95), drebrin, and amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) - and increased colocalization of PSD95 with synaptophysin. Notably, SPG302 proved efficacious in this model without modifying Aβ and tau pathology. Thus, our study provides preclinical support for the idea that compounds capable of restoring synaptic density offer a viable strategy to reverse cognitive decline in AD.
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Affiliation(s)
- Laura Trujillo-Estrada
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
- Departamento Biología Celular, Genetica y Fisiologia, Instituto de Investigacion Biomedica de Malaga-IBIMA, Facultad de Ciencias, Universidad de Malaga, Malaga, Spain
- Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Peter W Vanderklish
- Spinogenix Inc, 10210 Campus Point Drive, Suite 150, San Diego, CA, 92121, USA.
| | - Marie Minh Thu Nguyen
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Run Rong Kuang
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Caroline Nguyen
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Eric Huynh
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Celia da Cunha
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Dominic Ibarra Javonillo
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Stefania Forner
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Alessandra C Martini
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
| | - Stella T Sarraf
- Spinogenix Inc, 10210 Campus Point Drive, Suite 150, San Diego, CA, 92121, USA
| | - Vincent F Simmon
- Spinogenix Inc, 10210 Campus Point Drive, Suite 150, San Diego, CA, 92121, USA.
| | - David Baglietto-Vargas
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA.
- Department of Neurobiology and Behavior, University of California, Irvine, CA, 92697-1450, USA.
- Departamento Biología Celular, Genetica y Fisiologia, Instituto de Investigacion Biomedica de Malaga-IBIMA, Facultad de Ciencias, Universidad de Malaga, Malaga, Spain.
- Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
| | - Frank M LaFerla
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA.
- Department of Neurobiology and Behavior, University of California, Irvine, CA, 92697-1450, USA.
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16
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Walker CK, Herskowitz JH. Dendritic Spines: Mediators of Cognitive Resilience in Aging and Alzheimer's Disease. Neuroscientist 2021; 27:487-505. [PMID: 32812494 PMCID: PMC8130863 DOI: 10.1177/1073858420945964] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cognitive resilience is often defined as the ability to remain cognitively normal in the face of insults to the brain. These insults can include disease pathology, such as plaques and tangles associated with Alzheimer's disease, stroke, traumatic brain injury, or other lesions. Factors such as physical or mental activity and genetics may contribute to cognitive resilience, but the neurobiological underpinnings remain ill-defined. Emerging evidence suggests that dendritic spine structural plasticity is one plausible mechanism. In this review, we highlight the basic structure and function of dendritic spines and discuss how spine density and morphology change in aging and Alzheimer's disease. We note evidence that spine plasticity mediates resilience to stress, and we tackle dendritic spines in the context of cognitive resilience to Alzheimer's disease. Finally, we examine how lifestyle and genetic factors may influence dendritic spine plasticity to promote cognitive resilience before discussing evidence for actin regulatory kinases as therapeutic targets for Alzheimer's disease.
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Affiliation(s)
- Courtney K. Walker
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, University of Alabama at Birmingham, USA
| | - Jeremy H. Herskowitz
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, University of Alabama at Birmingham, USA
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17
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Cano-Astorga N, DeFelipe J, Alonso-Nanclares L. Three-Dimensional Synaptic Organization of Layer III of the Human Temporal Neocortex. Cereb Cortex 2021; 31:4742-4764. [PMID: 33999122 PMCID: PMC8408440 DOI: 10.1093/cercor/bhab120] [Citation(s) in RCA: 12] [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: 01/04/2023] Open
Abstract
In the present study, we have used focused ion beam/scanning electron microscopy (FIB/SEM) to perform a study of the synaptic organization of layer III of Brodmann's area 21 in human tissue samples obtained from autopsies and biopsies. We analyzed the synaptic density, 3D spatial distribution, and type (asymmetric/symmetric), as well as the size and shape of each synaptic junction of 4945 synapses that were fully reconstructed in 3D. Significant differences in the mean synaptic density between autopsy and biopsy samples were found (0.49 and 0.66 synapses/μm3, respectively). However, in both types of samples (autopsy and biopsy), the asymmetric:symmetric ratio was similar (93:7) and most asymmetric synapses were established on dendritic spines (75%), while most symmetric synapses were established on dendritic shafts (85%). We also compared several electron microscopy methods and analysis tools to estimate the synaptic density in the same brain tissue. We have shown that FIB/SEM is much more reliable and robust than the majority of the other commonly used EM techniques. The present work constitutes a detailed description of the synaptic organization of cortical layer III. Further studies on the rest of the cortical layers are necessary to better understand the functional organization of this temporal cortical region.
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Affiliation(s)
- Nicolás Cano-Astorga
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid 28002, Spain
| | - Javier DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid 28002, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Madrid 28031, Spain
| | - Lidia Alonso-Nanclares
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid 28002, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Madrid 28031, Spain
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18
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Kurucu H, Colom-Cadena M, Davies C, Wilkins L, King D, Rose J, Tzioras M, Tulloch JH, Smith C, Spires-Jones TL. Inhibitory synapse loss and accumulation of amyloid beta in inhibitory presynaptic terminals in Alzheimer's disease. Eur J Neurol 2021; 29:1311-1323. [PMID: 34331352 DOI: 10.1111/ene.15043] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/27/2021] [Accepted: 07/28/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND AND PURPOSE Synapse degeneration in Alzheimer's disease (AD) correlates strongly with cognitive decline. There is well-established excitatory synapse loss in AD with known contributions of pathological amyloid beta (Aβ) to excitatory synapse dysfunction and loss. Despite clear changes in circuit excitability in AD and model systems, relatively little is known about pathology in inhibitory synapses. METHODS Here human postmortem brain samples (n = 5 control, 10 AD cases) from temporal and occipital cortices were examined to investigate whether inhibitory synapses and neurons are lost in AD and whether Aβ may contribute to inhibitory synapse degeneration. Inhibitory neurons were counted in all six cortical layers using stereology software, and array tomography was used to examine synapse density and the accumulation of Aβ in synaptic terminals. RESULTS Differing inhibitory neuron densities were observed in the different cortical layers. The highest inhibitory neuron density was observed in layer 4 in both brain regions and the visual cortex had a higher inhibitory neuron density than the temporal cortex. There was significantly lower inhibitory neuron density in AD than in control cases in all six cortical layers. High-resolution array tomography imaging revealed plaque-associated loss of inhibitory synapses and accumulation of Aβ in a small subset of inhibitory presynaptic terminals with the most accumulation near amyloid plaques. CONCLUSIONS Inhibitory neuron and synapse loss in AD may contribute to disrupted excitatory/inhibitory balance and cognitive decline. Future work is warranted to determine whether targeting inhibitory synapse loss could be a useful therapeutic strategy.
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Affiliation(s)
- Hatice Kurucu
- University of Edinburgh Centre for Discovery Brain Sciences and UK Dementia Research Institute, Edinburgh, UK
| | - Martí Colom-Cadena
- University of Edinburgh Centre for Discovery Brain Sciences and UK Dementia Research Institute, Edinburgh, UK
| | - Caitlin Davies
- University of Edinburgh Centre for Discovery Brain Sciences and UK Dementia Research Institute, Edinburgh, UK
| | - Lewis Wilkins
- University of Edinburgh Centre for Discovery Brain Sciences and UK Dementia Research Institute, Edinburgh, UK
| | - Declan King
- University of Edinburgh Centre for Discovery Brain Sciences and UK Dementia Research Institute, Edinburgh, UK
| | - Jamie Rose
- University of Edinburgh Centre for Discovery Brain Sciences and UK Dementia Research Institute, Edinburgh, UK
| | - Makis Tzioras
- University of Edinburgh Centre for Discovery Brain Sciences and UK Dementia Research Institute, Edinburgh, UK
| | - Jane H Tulloch
- University of Edinburgh Centre for Discovery Brain Sciences and UK Dementia Research Institute, Edinburgh, UK
| | - Colin Smith
- Centre for Clinical Brain Sciences and Sudden Death Brain Bank, University of Edinburgh, Edinburgh, UK
| | - Tara L Spires-Jones
- University of Edinburgh Centre for Discovery Brain Sciences and UK Dementia Research Institute, Edinburgh, UK
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19
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Benavides-Piccione R, Regalado-Reyes M, Fernaud-Espinosa I, Kastanauskaite A, Tapia-González S, León-Espinosa G, Rojo C, Insausti R, Segev I, DeFelipe J. Differential Structure of Hippocampal CA1 Pyramidal Neurons in the Human and Mouse. Cereb Cortex 2021; 30:730-752. [PMID: 31268532 DOI: 10.1093/cercor/bhz122] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 05/07/2019] [Accepted: 05/13/2019] [Indexed: 11/13/2022] Open
Abstract
Pyramidal neurons are the most common cell type and are considered the main output neuron in most mammalian forebrain structures. In terms of function, differences in the structure of the dendrites of these neurons appear to be crucial in determining how neurons integrate information. To further shed light on the structure of the human pyramidal neurons we investigated the geometry of pyramidal cells in the human and mouse CA1 region-one of the most evolutionary conserved archicortical regions, which is critically involved in the formation, consolidation, and retrieval of memory. We aimed to assess to what extent neurons corresponding to a homologous region in different species have parallel morphologies. Over 100 intracellularly injected and 3D-reconstructed cells across both species revealed that dendritic and axonal morphologies of human cells are not only larger but also have structural differences, when compared to mouse. The results show that human CA1 pyramidal cells are not a stretched version of mouse CA1 cells. These results indicate that there are some morphological parameters of the pyramidal cells that are conserved, whereas others are species-specific.
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Affiliation(s)
- Ruth Benavides-Piccione
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid 28002, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
| | - Mamen Regalado-Reyes
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
| | - Isabel Fernaud-Espinosa
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
| | - Asta Kastanauskaite
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
| | - Silvia Tapia-González
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
| | - Gonzalo León-Espinosa
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain.,Departamento de Química y Bioquímica, Facultad de Farmacia, Universidad San Pablo Centro de Estudios Universitarios (CEU), Madrid 28925, Spain
| | - Concepcion Rojo
- Sección Departamental de Anatomía y Embriología (veterinaria). Facultad de Veterinaria. Universidad Complutense de Madrid 28040, Spain
| | - Ricardo Insausti
- Laboratorio de Neuroanatomía Humana, Facultad de Medicina, Universidad de Castilla-La Mancha, Albacete 02008, Spain
| | - Idan Segev
- Department of Neurobiology, Hebrew University of Jerusalem, Jerusalem 9190501, Israel.,Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Jerusalem 9190501, Israel
| | - Javier DeFelipe
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid 28002, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
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20
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Turegano-Lopez M, Santuy A, DeFelipe J, Merchan-Perez A. Size, Shape, and Distribution of Multivesicular Bodies in the Juvenile Rat Somatosensory Cortex: A 3D Electron Microscopy Study. Cereb Cortex 2021; 30:1887-1901. [PMID: 31665237 PMCID: PMC7132939 DOI: 10.1093/cercor/bhz211] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 07/30/2019] [Accepted: 08/16/2019] [Indexed: 12/27/2022] Open
Abstract
Multivesicular bodies (MVBs) are membrane-bound organelles that belong to the endosomal pathway. They participate in the transport, sorting, storage, recycling, degradation, and release of multiple substances. They interchange cargo with other organelles and participate in their renovation and degradation. We have used focused ion beam milling and scanning electron microscopy (FIB-SEM) to obtain stacks of serial sections from the neuropil of the somatosensory cortex of the juvenile rat. Using dedicated software, we have 3D-reconstructed 1618 MVBs. The mean density of MVBs was 0.21 per cubic micron. They were unequally distributed between dendrites (39.14%), axons (18.16%), and nonsynaptic cell processes (42.70%). About one out of five MVBs (18.16%) were docked on mitochondria, representing the process by which the endosomal pathway participates in mitochondrial maintenance. Other features of MVBs, such as the presence of tubular protrusions (6.66%) or clathrin coats (19.74%) can also be interpreted in functional terms, since both are typical of early endosomes. The sizes of MVBs follow a lognormal distribution, with differences across cortical layers and cellular compartments. The mean volume of dendritic MVBs is more than twice as large as the volume of axonic MVBs. In layer I, they are smaller, on average, than in the other layers.
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Affiliation(s)
- M Turegano-Lopez
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223 Madrid, Spain
| | - A Santuy
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223 Madrid, Spain
| | - J DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223 Madrid, Spain.,Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avda Doctor Arce, 37, 28002 Madrid, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) ISCIII, Madrid, Spain
| | - A Merchan-Perez
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223 Madrid, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) ISCIII, Madrid, Spain.,Departamento de Arquitectura y Tecnología de Sistemas Informáticos, Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223 Madrid, Spain
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21
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Parajuli LK, Koike M. Three-Dimensional Structure of Dendritic Spines Revealed by Volume Electron Microscopy Techniques. Front Neuroanat 2021; 15:627368. [PMID: 34135737 PMCID: PMC8200415 DOI: 10.3389/fnana.2021.627368] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 05/03/2021] [Indexed: 11/13/2022] Open
Abstract
Electron microscopy (EM)-based synaptology is a fundamental discipline for achieving a complex wiring diagram of the brain. A quantitative understanding of synaptic ultrastructure also serves as a basis to estimate the relative magnitude of synaptic transmission across individual circuits in the brain. Although conventional light microscopic techniques have substantially contributed to our ever-increasing understanding of the morphological characteristics of the putative synaptic junctions, EM is the gold standard for systematic visualization of the synaptic morphology. Furthermore, a complete three-dimensional reconstruction of an individual synaptic profile is required for the precise quantitation of different parameters that shape synaptic transmission. While volumetric imaging of synapses can be routinely obtained from the transmission EM (TEM) imaging of ultrathin sections, it requires an unimaginable amount of effort and time to reconstruct very long segments of dendrites and their spines from the serial section TEM images. The challenges of low throughput EM imaging have been addressed to an appreciable degree by the development of automated EM imaging tools that allow imaging and reconstruction of dendritic segments in a realistic time frame. Here, we review studies that have been instrumental in determining the three-dimensional ultrastructure of synapses. With a particular focus on dendritic spine synapses in the rodent brain, we discuss various key studies that have highlighted the structural diversity of spines, the principles of their organization in the dendrites, their presynaptic wiring patterns, and their activity-dependent structural remodeling.
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Affiliation(s)
- Laxmi Kumar Parajuli
- Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Masato Koike
- Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Tokyo, Japan.,Advanced Research Institute for Health Science, Juntendo University, Tokyo, Japan
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22
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Hong H, Yu X, Zhang R, Jiaerken Y, Wang S, Luo X, Lou M, Huang P, Zhang M. Cortical degeneration detected by neurite orientation dispersion and density imaging in chronic lacunar infarcts. Quant Imaging Med Surg 2021; 11:2114-2124. [PMID: 33936992 DOI: 10.21037/qims-20-880] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background Although lacunar infarcts are focal lesions, they may also have more widespread effects. A reduction in cortical thickness in the remote cortex after lacunar infarcts has been detected by structural imaging; however, its underlying microstructural changes are yet to be elucidated. This study aimed to investigate the effects of lacunar infarcts on the microstructural abnormalities associated with cortical thickness reduction in the remote cortex. Methods Thirty-seven patients with chronic lacunar infarcts were included. Brain structural magnetic resonance images (MRIs) and diffusion tensor images were acquired. We constructed the white matter tracts connecting with the lacunar infarcts and identified the connected cortical area based on a standard brain atlas warped into the subject space. Cortical thickness and microstructural neurite orientation dispersion and density imaging (NODDI) metrics of the ipsilesional and contralesional cortices were compared, and correlations between cortical thickness and NODDI metrics were also investigated. Results We found decreased cortical thickness and reduced neurite orientation dispersion index (ODI) in the ipsilesional cortex (2.47 vs. 2.50 mm, P=0.008; 0.451 vs. 0.456, P=0.035, respectively). In patients with precentral gyrus involvement (n=23), we found that ODI in the ipsilesional cortex was correlated with cortical thickness (r=0.437, P=0.037), and ODI in the contralesional cortex was also correlated with contralesional cortical thickness (r=0.440, P=0.036). Conclusions NODDI metrics could reflect cortical microstructural changes following lacunar infarcts. The correlation between decreased ODI and reduced cortical thickness suggests that dendrites' loss might contribute to lacunar infarct-related cortical atrophy.
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Affiliation(s)
- Hui Hong
- Department of Radiology, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, China
| | - Xinfeng Yu
- Department of Radiology, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, China
| | - Ruiting Zhang
- Department of Radiology, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, China
| | - Yeerfan Jiaerken
- Department of Radiology, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, China
| | - Shuyue Wang
- Department of Radiology, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, China
| | - Xiao Luo
- Department of Radiology, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, China
| | - Min Lou
- Department of Neurology, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, China
| | - Peiyu Huang
- Department of Radiology, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, China
| | - Minming Zhang
- Department of Radiology, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, China
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23
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Domínguez-Álvaro M, Montero-Crespo M, Blazquez-Llorca L, Plaza-Alonso S, Cano-Astorga N, DeFelipe J, Alonso-Nanclares L. 3D Analysis of the Synaptic Organization in the Entorhinal Cortex in Alzheimer's Disease. eNeuro 2021; 8:ENEURO.0504-20.2021. [PMID: 34039651 PMCID: PMC8225407 DOI: 10.1523/eneuro.0504-20.2021] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 03/26/2021] [Accepted: 04/16/2021] [Indexed: 01/01/2023] Open
Abstract
The entorhinal cortex (EC) is especially vulnerable in the early stages of Alzheimer's disease (AD). In particular, cognitive deficits have been linked to alterations in the upper layers of EC. In the present report, we examined Layers II and III from eight human brain autopsies (four subjects with no recorded neurologic alterations and four AD cases). We used stereological methods to assess cortical atrophy of the EC and possible changes in the volume occupied by different cortical elements (neuronal and glial cell bodies; blood vessels; and neuropil). We performed 3D ultrastructural analyses of synapses using focused ion beam/scanning electron microscopy (FIB/SEM) to examine possible alterations related to AD. At the light microscope level, we found a significantly lower volume fraction occupied by neuronal bodies in Layer III and a higher volume fraction occupied by glial cell bodies in Layer II in AD cases. At the ultrastructural level, we observed that (1) there was a significantly lower synaptic density in both layers in AD cases; (2) synapses were larger and more complex in Layer II in AD cases; and (3) there was a greater proportion of small and simple synapses in Layer III in AD cases than in control individuals. These structural differences may play a role in the anatomic basis for the impairment of cognitive functions in AD.
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Affiliation(s)
- M Domínguez-Álvaro
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
| | - M Montero-Crespo
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid 28002, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III 28031, Madrid, Spain
| | - L Blazquez-Llorca
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III 28031, Madrid, Spain
- Sección Departamental de Anatomía y Embriología (Veterinaria), Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid 28040, Spain
| | - S Plaza-Alonso
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid 28002, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III 28031, Madrid, Spain
| | - N Cano-Astorga
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid 28002, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III 28031, Madrid, Spain
| | - J DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid 28002, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III 28031, Madrid, Spain
| | - L Alonso-Nanclares
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid 28223, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid 28002, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III 28031, Madrid, Spain
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24
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Criado-Marrero M, Gebru NT, Blazier DM, Gould LA, Baker JD, Beaulieu-Abdelahad D, Blair LJ. Hsp90 co-chaperones, FKBP52 and Aha1, promote tau pathogenesis in aged wild-type mice. Acta Neuropathol Commun 2021; 9:65. [PMID: 33832539 PMCID: PMC8033733 DOI: 10.1186/s40478-021-01159-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 03/15/2021] [Indexed: 02/07/2023] Open
Abstract
The microtubule associated protein tau is an intrinsically disordered phosphoprotein that accumulates under pathological conditions leading to formation of neurofibrillary tangles, a hallmark of Alzheimer's disease (AD). The mechanisms that initiate the accumulation of phospho-tau aggregates and filamentous deposits are largely unknown. In the past, our work and others' have shown that molecular chaperones play a crucial role in maintaining protein homeostasis and that imbalance in their levels or activity can drive tau pathogenesis. We have found two co-chaperones of the 90 kDa heat shock protein (Hsp90), FK506-binding protein 52 (FKBP52) and the activator of Hsp90 ATPase homolog 1 (Aha1), promote tau aggregation in vitro and in the brains of tau transgenic mice. Based on this, we hypothesized that increased levels of these chaperones could promote tau misfolding and accumulation in the brains of aged wild-type mice. We tested this hypothesis by overexpressing Aha1, FKBP52, or mCherry (control) proteins in the hippocampus of 9-month-old wild-type mice. After 7 months of expression, mice were evaluated for cognitive and pathological changes. Our results show that FKBP52 overexpression impaired spatial reversal learning, while Aha1 overexpression impaired associative learning in aged wild-type mice. FKBP52 and Aha1 overexpression promoted phosphorylation of distinct AD-relevant tau species. Furthermore, FKBP52 activated gliosis and promoted neuronal loss leading to a reduction in hippocampal volume. Glial activation and phospho-tau accumulation were also detected in areas adjacent to the hippocampus, including the entorhinal cortex, suggesting that after initiation these pathologies can propagate through other brain regions. Overall, our findings suggest a role for chaperone imbalance in the initiation of tau accumulation in the aging brain.
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Affiliation(s)
- Marangelie Criado-Marrero
- USF Health Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, 33613, USA
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33620, USA
| | - Niat T Gebru
- USF Health Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, 33613, USA
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33620, USA
| | - Danielle M Blazier
- USF Health Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, 33613, USA
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33620, USA
| | - Lauren A Gould
- USF Health Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, 33613, USA
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33620, USA
| | - Jeremy D Baker
- USF Health Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, 33613, USA
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33620, USA
| | - David Beaulieu-Abdelahad
- USF Health Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, 33613, USA
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33620, USA
| | - Laura J Blair
- USF Health Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, 33613, USA.
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33620, USA.
- Research Service, James A Haley Veterans Hospital, 13000 Bruce B Downs Blvd, Tampa, FL, 33612, USA.
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25
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Blazquez-Llorca L, Miguéns M, Montero-Crespo M, Selvas A, Gonzalez-Soriano J, Ambrosio E, DeFelipe J. 3D Synaptic Organization of the Rat CA1 and Alterations Induced by Cocaine Self-Administration. Cereb Cortex 2021; 31:1927-1952. [PMID: 33253368 PMCID: PMC7945021 DOI: 10.1093/cercor/bhaa331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 09/10/2020] [Accepted: 10/12/2020] [Indexed: 12/24/2022] Open
Abstract
The hippocampus plays a key role in contextual conditioning and has been proposed as an important component of the cocaine addiction brain circuit. To gain knowledge about cocaine-induced alterations in this circuit, we used focused ion beam milling/scanning electron microscopy to reveal and quantify the three-dimensional synaptic organization of the neuropil of the stratum radiatum of the rat CA1, under normal circumstances and after cocaine-self administration (SA). Most synapses are asymmetric (excitatory), macular-shaped, and in contact with dendritic spine heads. After cocaine-SA, the size and the complexity of the shape of both asymmetric and symmetric (inhibitory) synapses increased but no changes were observed in the synaptic density. This work constitutes the first detailed report on the 3D synaptic organization in the stratum radiatum of the CA1 field of cocaine-SA rats. Our data contribute to the elucidation of the normal and altered synaptic organization of the hippocampus, which is crucial for better understanding the neurobiological mechanisms underlying cocaine addiction.
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Affiliation(s)
- L Blazquez-Llorca
- Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Madrid, Spain.,Sección Departamental de Anatomía y Embriología (Veterinaria), Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - M Miguéns
- Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain
| | - M Montero-Crespo
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Madrid, Spain.,Instituto Cajal, Consejo Superior de Investigaciones Científicas, 28002 Madrid, Spain
| | - A Selvas
- Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain
| | - J Gonzalez-Soriano
- Sección Departamental de Anatomía y Embriología (Veterinaria), Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - E Ambrosio
- Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain
| | - J DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Madrid, Spain.,Instituto Cajal, Consejo Superior de Investigaciones Científicas, 28002 Madrid, Spain
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26
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Montero-Crespo M, Domínguez-Álvaro M, Alonso-Nanclares L, DeFelipe J, Blazquez-Llorca L. Three-dimensional analysis of synaptic organization in the hippocampal CA1 field in Alzheimer's disease. Brain 2021; 144:553-573. [PMID: 33324984 PMCID: PMC8240746 DOI: 10.1093/brain/awaa406] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 09/07/2020] [Accepted: 09/20/2020] [Indexed: 02/06/2023] Open
Abstract
Alzheimer's disease is the most common form of dementia, characterized by a persistent and progressive impairment of cognitive functions. Alzheimer's disease is typically associated with extracellular deposits of amyloid-β peptide and accumulation of abnormally phosphorylated tau protein inside neurons (amyloid-β and neurofibrillary pathologies). It has been proposed that these pathologies cause neuronal degeneration and synaptic alterations, which are thought to constitute the major neurobiological basis of cognitive dysfunction in Alzheimer's disease. The hippocampal formation is especially vulnerable in the early stages of Alzheimer's disease. However, the vast majority of electron microscopy studies have been performed in animal models. In the present study, we performed an extensive 3D study of the neuropil to investigate the synaptic organization in the stratum pyramidale and radiatum in the CA1 field of Alzheimer's disease cases with different stages of the disease, using focused ion beam/scanning electron microscopy (FIB/SEM). In cases with early stages of Alzheimer's disease, the synapse morphology looks normal and we observed no significant differences between control and Alzheimer's disease cases regarding the synaptic density, the ratio of excitatory and inhibitory synapses, or the spatial distribution of synapses. However, differences in the distribution of postsynaptic targets and synaptic shapes were found. Furthermore, a lower proportion of larger excitatory synapses in both strata were found in Alzheimer's disease cases. Individuals in late stages of the disease suffered the most severe synaptic alterations, including a decrease in synaptic density and morphological alterations of the remaining synapses. Since Alzheimer's disease cases show cortical atrophy, our data indicate a reduction in the total number (but not the density) of synapses at early stages of the disease, with this reduction being much more accentuated in subjects with late stages of Alzheimer's disease. The observed synaptic alterations may represent a structural basis for the progressive learning and memory dysfunctions seen in Alzheimer's disease cases.
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Affiliation(s)
- Marta Montero-Crespo
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Av. Doctor Arce, 37, 28002 Madrid, Spain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid, Spain
| | - Marta Domínguez-Álvaro
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid, Spain
| | - Lidia Alonso-Nanclares
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Av. Doctor Arce, 37, 28002 Madrid, Spain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, c/Valderrebollo, 5, 28031 Madrid, Spain
| | - Javier DeFelipe
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Av. Doctor Arce, 37, 28002 Madrid, Spain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, c/Valderrebollo, 5, 28031 Madrid, Spain
| | - Lidia Blazquez-Llorca
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, c/Valderrebollo, 5, 28031 Madrid, Spain
- Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), c/Juan del Rosal, 10, 28040 Madrid, Spain
- Sección Departamental de Anatomía y Embriología (Veterinaria), Facultad de Veterinaria, Universidad Complutense de Madrid, Av. Puerta de Hierro, s/n, 28040 Madrid, Spain
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27
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Wang Z, Yang J, Zhu W, Tang Y, Jia J. The synaptic marker neurogranin as a disease state biomarker in Alzheimer's disease: a systematic review and meta-analysis. Int J Neurosci 2021; 132:1245-1253. [PMID: 33527855 DOI: 10.1080/00207454.2021.1881087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Objective: Synaptic degeneration is the pathologic foundation of cognitive decline in the Alzheimer's disease (AD) continuum. We aimed to determine whether cerebrospinal fluid (CSF) synaptic marker neurogranin (Ng) is a disease state or a disease stage biomarker in the AD continuum.Methods: Studies comparing CSF Ng levels among AD, mild cognitive impairment (MCI) and healthy participants were included. Studies were eligible if the correlation between CSF Ng levels and Mini-Mental Status Examination (MMSE) scores was investigated.Results: Twenty-one studies met our inclusion criteria (n = 4515). The magnitude of effect sizes was more apparent in AD (standardized mean difference [SMD] = 1.72; 95% confidence interval [CI] = 1.23-2.22), than in MCI (SMD = 0.82; 95% CI = 0.29-1.34) compared to control populations. These results suggest that CSF Ng can discriminate AD and MCI from control populations, implying that synaptic degeneration worsens as patients progress from MCI to AD. However, there was a very weak correlation between CSF Ng levels and MMSE scores (r = -0.15; 95% CI = -0.21--0.08) among the whole populations, suggesting that an increment of CSF Ng is best considered a biological evidence of disease state in the AD continuum.Conclusion: Our study provides evidence that the synaptic marker CSF Ng can be used as a disease state biomarker for the AD continuum. Because synaptic degeneration is a distinct pathologic event from amyloid deposition and neurofibrillary tangle formation, CSF Ng may provide an important supplementation to the AT(N) biomarker system to reveal the sequence of neuropathology.
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Affiliation(s)
- Zhibin Wang
- Innovation Center for Neurological Disorders, Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, China
| | - Jianwei Yang
- Innovation Center for Neurological Disorders, Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, China
| | - Wei Zhu
- Innovation Center for Neurological Disorders, Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, China
| | - Yi Tang
- Innovation Center for Neurological Disorders, Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, China.,Neurodegenerative Laboratory of Ministry of Education of the People's Republic of China, Beijing, China
| | - Jianping Jia
- Innovation Center for Neurological Disorders, Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, China.,Beijing Key Laboratory of Geriatric Cognitive Disorders, Beijing, China.,Clinical Center for Neurodegenerative Disease and Memory Impairment, Capital Medical University, Beijing, China.,Center of Alzheimer's Disease, Beijing Institute for Brain Disorders, Beijing, China
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28
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Domínguez-Álvaro M, Montero-Crespo M, Blazquez-Llorca L, DeFelipe J, Alonso-Nanclares L. 3D Ultrastructural Study of Synapses in the Human Entorhinal Cortex. Cereb Cortex 2020; 31:410-425. [PMID: 32887978 PMCID: PMC7727377 DOI: 10.1093/cercor/bhaa233] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/24/2020] [Accepted: 07/28/2020] [Indexed: 01/01/2023] Open
Abstract
The entorhinal cortex (EC) is a brain region that has been shown to be essential for memory functions and spatial navigation. However, detailed three-dimensional (3D) synaptic morphology analysis and identification of postsynaptic targets at the ultrastructural level have not been performed before in the human EC. In the present study, we used Focused Ion Beam/Scanning Electron Microscopy to perform a 3D analysis of the synapses in the neuropil of medial EC in layers II and III from human brain autopsies. Specifically, we studied synaptic structural parameters of 3561 synapses, which were fully reconstructed in 3D. We analyzed the synaptic density, 3D spatial distribution, and type (excitatory and inhibitory), as well as the shape and size of each synaptic junction. Moreover, the postsynaptic targets of synapses could be clearly determined. The present work constitutes a detailed description of the synaptic organization of the human EC, which is a necessary step to better understand the functional organization of this region in both health and disease.
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Affiliation(s)
- M Domínguez-Álvaro
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid. Pozuelo de Alarcón, Madrid 28223, Spain
| | - M Montero-Crespo
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid. Pozuelo de Alarcón, Madrid 28223, Spain.,Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Doctor Arce, 37 Madrid, 28002, Spain
| | - L Blazquez-Llorca
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid. Pozuelo de Alarcón, Madrid 28223, Spain.,Depto. Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), c/Juan del Rosal, 10, Madrid 28040, Spain
| | - J DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid. Pozuelo de Alarcón, Madrid 28223, Spain.,Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Doctor Arce, 37 Madrid, 28002, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), c/Valderrebollo, 5, Madrid 28031, Spain
| | - L Alonso-Nanclares
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid. Pozuelo de Alarcón, Madrid 28223, Spain.,Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Doctor Arce, 37 Madrid, 28002, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), c/Valderrebollo, 5, Madrid 28031, Spain
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29
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Ren JM, Zhang SL, Wang XL, Guan ZZ, Qi XL. Expression levels of the α7 nicotinic acetylcholine receptor in the brains of patients with Alzheimer's disease and their effect on synaptic proteins in SH-SY5Y cells. Mol Med Rep 2020; 22:2063-2075. [PMID: 32582986 PMCID: PMC7411404 DOI: 10.3892/mmr.2020.11253] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 06/04/2020] [Indexed: 01/22/2023] Open
Abstract
Alzheimer's disease (AD) is a chronic neurodegenerative, and abnormal aggregation of the neurotoxic β amyloid (Aβ) peptide is an early event in AD. The present study aimed to determine the correlation between the nicotinic acetylcholine receptor α7 subunit (α7 nAChR) and Aβ in the brains of patients with AD, and to investigate whether the increased expression levels of the α7 nAChR could alter the neurotoxicity of Aβ. The expression levels of α7 nAChR and Aβ in the brains of patients with AD and healthy brains were analyzed using immunofluorescence. Moreover, SH‑SY5Y cells were used to stably overexpress or silence α7 nAChR expression levels, prior to the treatment with or without 1 µmol/l Aβ1‑42 oligomer (AβO). The mRNA and protein expression levels of α7 nAChR, synaptophysin (SYP), postsynaptic density of 95 kDa (PSD‑95) and synaptosomal‑associated protein of 25 kDa (SNAP‑25) were subsequently analyzed using reverse transcription‑quantitative PCR and western blotting. In addition, the concentration of acetylcholine (ACh) and the activity of acetylcholinesterase (AChE) were analyzed using spectrophotometry, while the cell apoptotic rate was determined using flow cytometry. The expression of Aβ in the brains of patients with AD was found to be significantly increased, whereas the expression of α7 nAChR was significantly decreased compared with the healthy control group. In vitro, the expression levels of α7 nAChR were significantly increased or decreased following the overexpression or silencing of the gene, respectively. Consistent with these observations, the mRNA and protein expression levels of SYP, PSD‑95 and SNAP‑25 were also significantly increased following the overexpression of α7 nAChR and decreased following the genetic silencing of the receptor. In untransfected or negative control cells, the expression levels of these factors and the apoptotic rate were significantly reduced following the exposure to AβO, which was found to be attenuated by α7 nAChR overexpression, but potentiated by α7 nAChR RNA silencing. However, no significant differences were observed in either the ACh concentration or AChE activity following transfection. Collectively, these findings suggested that α7 nAChR may protect the brains of patients with AD against Aβ, as α7 nAChR overexpression increased the expression levels of SYP, SNAP‑25 and PSD‑95, and attenuated the inhibitory effect of Aβ on the expression of these synaptic proteins and cell apoptosis. Overall, this indicated that α7 nAChR may serve an important neuroprotective role in AD.
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Affiliation(s)
- Jia-Mou Ren
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education, Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
- Key Laboratory of Medical Molecular Biology, Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
- Department of Basic Medicine, Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
| | - Shu-Li Zhang
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education, Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
- Key Laboratory of Medical Molecular Biology, Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
- Chinese People's Liberation Army, Secret Service Center Sanatorium of Xiamen, Xiamen, Fujian 361000, P.R. China
| | - Xiao-Ling Wang
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education, Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
- Key Laboratory of Medical Molecular Biology, Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
| | - Zhi-Zhong Guan
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education, Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
- Key Laboratory of Medical Molecular Biology, Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
- Department of Pathology, Affiliated Hospital of Guizhou Medical University, Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
| | - Xiao-Lan Qi
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education, Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
- Key Laboratory of Medical Molecular Biology, Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
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30
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Montero-Crespo M, Dominguez-Alvaro M, Rondon-Carrillo P, Alonso-Nanclares L, DeFelipe J, Blazquez-Llorca L. Three-dimensional synaptic organization of the human hippocampal CA1 field. eLife 2020; 9:e57013. [PMID: 32690133 PMCID: PMC7375818 DOI: 10.7554/elife.57013] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 06/10/2020] [Indexed: 12/14/2022] Open
Abstract
The hippocampal CA1 field integrates a wide variety of subcortical and cortical inputs, but its synaptic organization in humans is still unknown due to the difficulties involved studying the human brain via electron microscope techniques. However, we have shown that the 3D reconstruction method using Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM) can be applied to study in detail the synaptic organization of the human brain obtained from autopsies, yielding excellent results. Using this technology, 24,752 synapses were fully reconstructed in CA1, revealing that most of them were excitatory, targeting dendritic spines and displaying a macular shape, regardless of the layer examined. However, remarkable differences were observed between layers. These data constitute the first extensive description of the synaptic organization of the neuropil of the human CA1 region.
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Affiliation(s)
- Marta Montero-Crespo
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC)MadridSpain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadridSpain
| | - Marta Dominguez-Alvaro
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadridSpain
| | - Patricia Rondon-Carrillo
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadridSpain
| | - Lidia Alonso-Nanclares
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC)MadridSpain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadridSpain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIIIMadridSpain
| | - Javier DeFelipe
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC)MadridSpain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadridSpain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIIIMadridSpain
| | - Lidia Blazquez-Llorca
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de MadridMadridSpain
- Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED)MadridSpain
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31
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Sanderson JB, De S, Jiang H, Rovere M, Jin M, Zaccagnini L, Hays Watson A, De Boni L, Lagomarsino VN, Young-Pearse TL, Liu X, Pochapsky TC, Hyman BT, Dickson DW, Klenerman D, Selkoe DJ, Bartels T. Analysis of α-synuclein species enriched from cerebral cortex of humans with sporadic dementia with Lewy bodies. Brain Commun 2020; 2:fcaa010. [PMID: 32280944 PMCID: PMC7130446 DOI: 10.1093/braincomms/fcaa010] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 12/23/2019] [Accepted: 01/09/2020] [Indexed: 02/06/2023] Open
Abstract
Since researchers identified α-synuclein as the principal component of Lewy bodies and Lewy neurites, studies have suggested that it plays a causative role in the pathogenesis of dementia with Lewy bodies and other ‘synucleinopathies’. While α-synuclein dyshomeostasis likely contributes to the neurodegeneration associated with the synucleinopathies, few direct biochemical analyses of α-synuclein from diseased human brain tissue currently exist. In this study, we analysed sequential protein extracts from a substantial number of patients with neuropathological diagnoses of dementia with Lewy bodies and corresponding controls, detecting a shift of cytosolic and membrane-bound physiological α-synuclein to highly aggregated forms. We then fractionated aqueous extracts (cytosol) from cerebral cortex using non-denaturing methods to search for soluble, disease-associated high molecular weight species potentially associated with toxicity. We applied these fractions and corresponding insoluble fractions containing Lewy-type aggregates to several reporter assays to determine their bioactivity and cytotoxicity. Ultimately, high molecular weight cytosolic fractions enhances phospholipid membrane permeability, while insoluble, Lewy-associated fractions induced morphological changes in the neurites of human stem cell-derived neurons. While the concentrations of soluble, high molecular weight α-synuclein were only slightly elevated in brains of dementia with Lewy bodies patients compared to healthy, age-matched controls, these observations suggest that a small subset of soluble α-synuclein aggregates in the brain may drive early pathogenic effects, while Lewy body-associated α-synuclein can drive neurotoxicity.
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Affiliation(s)
- John B Sanderson
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Suman De
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK.,UK Dementia Research Institute, Department of Chemistry, University of Cambridge, Cambridge CB2 0AH, UK
| | - Haiyang Jiang
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Matteo Rovere
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Ming Jin
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Ludovica Zaccagnini
- UK Dementia Research Institute, Department of Neurology, University College London, London WC1E 6BT, UK
| | - Aurelia Hays Watson
- UK Dementia Research Institute, Department of Neurology, University College London, London WC1E 6BT, UK
| | - Laura De Boni
- UK Dementia Research Institute, Department of Neurology, University College London, London WC1E 6BT, UK
| | - Valentina N Lagomarsino
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Tracy L Young-Pearse
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Xinyue Liu
- Department of Chemistry, Rosenstiel Institute for Basic Biomedical Research, Brandeis University, Waltham, MA 02453, USA
| | - Thomas C Pochapsky
- Department of Chemistry, Rosenstiel Institute for Basic Biomedical Research, Brandeis University, Waltham, MA 02453, USA
| | - Bradley T Hyman
- Massachusetts General Hospital, Harvard Medical School, Department of Neurology, Massachusetts Institute for Neurodegenerative Disease, Boston, MA 02129, USA
| | - Dennis W Dickson
- Neuropathology Laboratory, Department of Neuroscience, Mayo Clinic Jacksonville, Jacksonville, FL 32224, USA
| | - David Klenerman
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK.,UK Dementia Research Institute, Department of Chemistry, University of Cambridge, Cambridge CB2 0AH, UK
| | - Dennis J Selkoe
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Tim Bartels
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.,UK Dementia Research Institute, Department of Neurology, University College London, London WC1E 6BT, UK
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32
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Ranneva SV, Maksimov VF, Korostyshevskaja IM, Lipina TV. Lack of synaptic protein, calsyntenin‐2, impairs morphology of synaptic complexes in mice. Synapse 2019; 74:e22132. [DOI: 10.1002/syn.22132] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 09/05/2019] [Accepted: 09/11/2019] [Indexed: 12/31/2022]
Affiliation(s)
- Svetlana V. Ranneva
- Federal State Budgetary Scientific Institution Scientific Research Institute of Physiology and Basic Medicine Novosibirsk Russia
| | - Valeriy F. Maksimov
- Federal State Budgetary Scientific Institution Scientific Research Institute of Physiology and Basic Medicine Novosibirsk Russia
| | - Irina M. Korostyshevskaja
- Federal State Budgetary Scientific Institution Scientific Research Institute of Physiology and Basic Medicine Novosibirsk Russia
| | - Tatiana V. Lipina
- Federal State Budgetary Scientific Institution Scientific Research Institute of Physiology and Basic Medicine Novosibirsk Russia
- Department of Medicine and Psychology Novosibirsk State University Novosibirsk Russia
- Department of Pharmacology and Toxicology University of Toronto Toronto Ontario Canada
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33
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3D Electron Microscopy Study of Synaptic Organization of the Normal Human Transentorhinal Cortex and Its Possible Alterations in Alzheimer's Disease. eNeuro 2019; 6:ENEURO.0140-19.2019. [PMID: 31217195 PMCID: PMC6620390 DOI: 10.1523/eneuro.0140-19.2019] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/23/2019] [Accepted: 05/27/2019] [Indexed: 01/10/2023] Open
Abstract
The transentorhinal cortex (TEC) is an obliquely oriented cortex located in the medial temporal lobe and, together with the entorhinal cortex, is one of the first affected areas in Alzheimer’s disease (AD). One of the most widely accepted hypotheses is that synaptopathy (synaptic alterations and loss) represents the major structural correlate of the cognitive decline observed in AD. However, very few electron microscope (EM) studies are available; the most common method to estimate synaptic density indirectly is by counting, at the light microscopic level, immunoreactive puncta using synaptic markers. To investigate synaptic morphology and possible alterations related to AD, a detailed three-dimensional (3D) ultrastructural analysis using focused ion beam/scanning EM (FIB/SEM) was performed in the neuropil of Layer II of the TEC in human brain samples from non-demented subjects and AD patients. Evaluation of the proportion and shape of asymmetric synapses (AS) and symmetric synapses (SS) targeting spines or dendritic shafts was performed using 3D reconstructions of every synapse. The 3D analysis of 4722 synapses revealed that the preferable targets were spine heads for AS and dendritic shafts for SS, both in control and AD cases. However, in AD patients, we observed a reduction in the percentage of synapses targeting spine heads. Regarding the shape of synapses, in both control cases and AD samples, the vast majority of synapses had a macular shape, followed by perforated or horseshoe-shaped synapses, with fragmented synapses being the least frequent type. Moreover, comparisons showed an increased number of fragmented AS in AD patients.
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34
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Rolnick D, Dyer EL. Generative models and abstractions for large-scale neuroanatomy datasets. Curr Opin Neurobiol 2019; 55:112-120. [PMID: 30878806 PMCID: PMC8449855 DOI: 10.1016/j.conb.2019.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 01/09/2019] [Accepted: 02/07/2019] [Indexed: 01/09/2023]
Abstract
Neural datasets are increasing rapidly in both resolution and volume. In neuroanatomy, this trend has been accelerated by innovations in imaging technology. As full datasets are impractical and unnecessary for many applications, it is important to identify abstractions that distill useful features of neural structure, organization, and anatomy. In this review article, we discuss several such abstractions and highlight recent algorithmic advances in working with these models. In particular, we discuss the use of generative models in neuroanatomy; such models may be considered 'meta-abstractions' that capture distributions over other abstractions.
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Affiliation(s)
- David Rolnick
- School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA
| | - Eva L Dyer
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta, GA, USA; School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
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Region-specific depletion of synaptic mitochondria in the brains of patients with Alzheimer's disease. Acta Neuropathol 2018; 136:747-757. [PMID: 30191401 PMCID: PMC6208730 DOI: 10.1007/s00401-018-1903-2] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 08/22/2018] [Accepted: 08/22/2018] [Indexed: 01/04/2023]
Abstract
Of all of the neuropathological changes observed in Alzheimer’s disease (AD), the loss of synapses correlates most strongly with cognitive decline. The precise mechanisms of synapse degeneration in AD remain unclear, although strong evidence indicates that pathological forms of both amyloid beta and tau contribute to synaptic dysfunction and loss. Synaptic mitochondria play a potentially important role in synapse degeneration in AD. Many studies in model systems indicate that amyloid beta and tau both impair mitochondrial function and impair transport of mitochondria to synapses. To date, much less is known about whether synaptic mitochondria are affected in human AD brain. Here, we used transmission electron microscopy to examine synapses and synaptic mitochondria in two cortical regions (BA41/42 and BA46) from eight AD and nine control cases. In this study, we observed 3000 synapses and find region-specific differences in synaptic mitochondria in AD cases compared to controls. In BA41/42, we observe a fourfold reduction in the proportion of presynaptic terminals that contain multiple mitochondria profiles in AD. We also observe ultrastructural changes including abnormal mitochondrial morphology, the presence of multivesicular bodies in synapses, and reduced synapse apposition length near plaques in AD. Together, our data show region-specific changes in synaptic mitochondria in AD and support the idea that the transport of mitochondria to presynaptic terminals or synaptic mitochondrial dynamics may be altered in AD.
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Evidence for altered dendritic spine compartmentalization in Alzheimer's disease and functional effects in a mouse model. Acta Neuropathol 2018; 135:839-854. [PMID: 29696365 DOI: 10.1007/s00401-018-1847-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 03/30/2018] [Accepted: 04/05/2018] [Indexed: 12/23/2022]
Abstract
Alzheimer's disease (AD) is associated with a progressive loss of synapses and neurons. Studies in animal models indicate that morphological alterations of dendritic spines precede synapse loss, increasing the proportion of large and short ("stubby") spines. Whether similar alterations occur in human patients, and what their functional consequences could be, is not known. We analyzed biopsies from AD patients and APP x presenilin 1 knock-in mice that were previously shown to present a loss of pyramidal neurons in the CA1 area of the hippocampus. We observed that the proportion of stubby spines and the width of spine necks are inversely correlated with synapse density in frontal cortical biopsies from non-AD and AD patients. In mice, the reduction in the density of synapses in the stratum radiatum was preceded by an alteration of spine morphology, with a reduction of their length and an enlargement of their neck. Serial sectioning examined with electron microscopy allowed us to precisely measure spine parameters. Mathematical modeling indicated that the shortening and widening of the necks should alter the electrical compartmentalization of the spines, leading to reduced postsynaptic potentials in spine heads, but not in soma. Accordingly, there was no alteration in basal synaptic transmission, but long-term potentiation and spatial memory were impaired. These results indicate that an alteration of spine morphology could be involved in the early cognitive deficits associated with AD.
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