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Vandael D, Jonas P. Structure, biophysics, and circuit function of a "giant" cortical presynaptic terminal. Science 2024; 383:eadg6757. [PMID: 38452088 DOI: 10.1126/science.adg6757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 01/19/2024] [Indexed: 03/09/2024]
Abstract
The hippocampal mossy fiber synapse, formed between axons of dentate gyrus granule cells and dendrites of CA3 pyramidal neurons, is a key synapse in the trisynaptic circuitry of the hippocampus. Because of its comparatively large size, this synapse is accessible to direct presynaptic recording, allowing a rigorous investigation of the biophysical mechanisms of synaptic transmission and plasticity. Furthermore, because of its placement in the very center of the hippocampal memory circuit, this synapse seems to be critically involved in several higher network functions, such as learning, memory, pattern separation, and pattern completion. Recent work based on new technologies in both nanoanatomy and nanophysiology, including presynaptic patch-clamp recording, paired recording, super-resolution light microscopy, and freeze-fracture and "flash-and-freeze" electron microscopy, has provided new insights into the structure, biophysics, and network function of this intriguing synapse. This brings us one step closer to answering a fundamental question in neuroscience: how basic synaptic properties shape higher network computations.
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Affiliation(s)
- David Vandael
- Institute of Science and Technology Austria (ISTA), A-3400 Klosterneuburg, Austria
| | - Peter Jonas
- Institute of Science and Technology Austria (ISTA), A-3400 Klosterneuburg, Austria
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2
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Chaudhary P, Lockwood H, Stowell C, Bushong E, Reynaud J, Yang H, Gardiner SK, Wiliams G, Williams I, Ellisman M, Marsh-Armstrong N, Burgoyne C. Retrolaminar Demyelination of Structurally Intact Axons in Nonhuman Primate Experimental Glaucoma. Invest Ophthalmol Vis Sci 2024; 65:36. [PMID: 38407858 PMCID: PMC10902877 DOI: 10.1167/iovs.65.2.36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 01/28/2024] [Indexed: 02/27/2024] Open
Abstract
Purpose To determine if structurally intact, retrolaminar optic nerve (RON) axons are demyelinated in nonhuman primate (NHP) experimental glaucoma (EG). Methods Unilateral EG NHPs (n = 3) were perfusion fixed, EG and control eyes were enucleated, and foveal Bruch's membrane opening (FoBMO) 30° sectoral axon counts were estimated. Optic nerve heads were trephined; serial vibratome sections (VSs) were imaged and colocalized to a fundus photograph establishing their FoBMO location. The peripheral neural canal region within n = 5 EG versus control eye VS comparisons was targeted for scanning block-face electron microscopic reconstruction (SBEMR) using micro-computed tomographic reconstructions (µCTRs) of each VS. Posterior laminar beams within each µCTR were segmented, allowing a best-fit posterior laminar surface (PLS) to be colocalized into its respective SBEMR. Within each SBEMR, up to 300 axons were randomly traced until they ended (nonintact) or left the block (intact). For each intact axon, myelin onset was identified and myelin onset distance (MOD) was measured relative to the PLS. For each EG versus control SBEMR comparison, survival analyses compared EG and control MOD. Results MOD calculations were successful in three EG and five control eye SBEMRs. Within each SBEMR comparison, EG versus control eye axon loss was -32.9%, -8.3%, and -15.2% (respectively), and MOD was increased in the EG versus control SBEMR (P < 0.0001 for each EG versus control SBEMR comparison). When data from all three EG eye SBEMRs were compared to all five control eye SBEMRs, MOD was increased within the EG eyes. Conclusions Structurally intact, RON axons are demyelinated in NHP early to moderate EG. Studies to determine their functional status are indicated.
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Affiliation(s)
- Priya Chaudhary
- Optic Nerve Head Research Laboratory, Legacy Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
- Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Howard Lockwood
- Optic Nerve Head Research Laboratory, Legacy Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
- Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Cheri Stowell
- Optic Nerve Head Research Laboratory, Legacy Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
- Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Eric Bushong
- National Center for Microscopy & Imaging Research, UCSD, La Jolla, California, United States
| | - Juan Reynaud
- Optic Nerve Head Research Laboratory, Legacy Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
- Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Hongli Yang
- Optic Nerve Head Research Laboratory, Legacy Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
- Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Stuart K Gardiner
- Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Galen Wiliams
- Optic Nerve Head Research Laboratory, Legacy Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
- Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Imee Williams
- Optic Nerve Head Research Laboratory, Legacy Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
- Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Mark Ellisman
- National Center for Microscopy & Imaging Research, UCSD, La Jolla, California, United States
| | - Nick Marsh-Armstrong
- Department of Ophthalmology, University of California, Davis, California, United States
| | - Claude Burgoyne
- Optic Nerve Head Research Laboratory, Legacy Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
- Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
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3
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Dixit D, Hallisey VM, Zhu EY, Okuniewska M, Cadwell K, Chipuk JE, Axelrad JE, Schwab SR. S1PR1 inhibition induces proapoptotic signaling in T cells and limits humoral responses within lymph nodes. J Clin Invest 2024; 134:e174984. [PMID: 38194271 PMCID: PMC10869180 DOI: 10.1172/jci174984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 12/21/2023] [Indexed: 01/10/2024] Open
Abstract
Effective immunity requires a large, diverse naive T cell repertoire circulating among lymphoid organs in search of antigen. Sphingosine 1-phosphate (S1P) and its receptor S1PR1 contribute by both directing T cell migration and supporting T cell survival. Here, we addressed how S1P enables T cell survival and the implications for patients treated with S1PR1 antagonists. We found that S1PR1 limited apoptosis by maintaining the appropriate balance of BCL2 family members via restraint of JNK activity. Interestingly, the same residues of S1PR1 that enable receptor internalization were required to prevent this proapoptotic cascade. Findings in mice were recapitulated in ulcerative colitis patients treated with the S1PR1 antagonist ozanimod, and the loss of naive T cells limited B cell responses. Our findings highlighted an effect of S1PR1 antagonists on the ability to mount immune responses within lymph nodes, beyond their effect on lymph node egress, and suggested both limitations and additional uses of this important class of drugs.
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Affiliation(s)
- Dhaval Dixit
- Departments of Cell Biology and Pathology, New York University Grossman School of Medicine, New York, New York, USA
| | - Victoria M. Hallisey
- Departments of Cell Biology and Pathology, New York University Grossman School of Medicine, New York, New York, USA
| | - Ethan Y.S. Zhu
- Departments of Cell Biology and Pathology, New York University Grossman School of Medicine, New York, New York, USA
| | - Martyna Okuniewska
- Departments of Cell Biology and Pathology, New York University Grossman School of Medicine, New York, New York, USA
| | - Ken Cadwell
- Department of Medicine and Institute for Immunology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Jerry E. Chipuk
- Department of Oncological Sciences, Department of Dermatology, and Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Jordan E. Axelrad
- Division of Gastroenterology, Department of Medicine, New York University Grossman School of Medicine, New York, New York, USA
| | - Susan R. Schwab
- Departments of Cell Biology and Pathology, New York University Grossman School of Medicine, New York, New York, USA
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4
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Thomas CI, Ryan MA, Kamasawa N, Scholl B. Postsynaptic mitochondria are positioned to support functional diversity of dendritic spines. eLife 2023; 12:RP89682. [PMID: 38059805 PMCID: PMC10703439 DOI: 10.7554/elife.89682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2023] Open
Abstract
Postsynaptic mitochondria are critical for the development, plasticity, and maintenance of synaptic inputs. However, their relationship to synaptic structure and functional activity is unknown. We examined a correlative dataset from ferret visual cortex with in vivo two-photon calcium imaging of dendritic spines during visual stimulation and electron microscopy reconstructions of spine ultrastructure, investigating mitochondrial abundance near functionally and structurally characterized spines. Surprisingly, we found no correlation to structural measures of synaptic strength. Instead, we found that mitochondria are positioned near spines with orientation preferences that are dissimilar to the somatic preference. Additionally, we found that mitochondria are positioned near groups of spines with heterogeneous orientation preferences. For a subset of spines with a mitochondrion in the head or neck, synapses were larger and exhibited greater selectivity to visual stimuli than those without a mitochondrion. Our data suggest mitochondria are not necessarily positioned to support the energy needs of strong spines, but rather support the structurally and functionally diverse inputs innervating the basal dendrites of cortical neurons.
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Affiliation(s)
- Connon I Thomas
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, Max Planck WayJupiterUnited States
| | - Melissa A Ryan
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, Max Planck WayJupiterUnited States
| | - Naomi Kamasawa
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, Max Planck WayJupiterUnited States
| | - Benjamin Scholl
- Department of Neuroscience, Perelman School of Medicine at the University of PennsylvaniaPhiladelphiaUnited States
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5
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Thomas CI, Ryan MA, Kamasawa N, Scholl B. Postsynaptic mitochondria are positioned to support functional diversity of dendritic spines. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.14.549063. [PMID: 37502969 PMCID: PMC10370038 DOI: 10.1101/2023.07.14.549063] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Postsynaptic mitochondria are critical to the development, plasticity, and maintenance of synaptic inputs. However, their relationship to synaptic structure and functional activity is unknown. We examined a correlative dataset from ferret visual cortex with in vivo two-photon calcium imaging of dendritic spines during visual stimulation and electron microscopy (EM) reconstructions of spine ultrastructure, investigating mitochondrial abundance near functionally- and structurally-characterized spines. Surprisingly, we found no correlation to structural measures of synaptic strength. Instead, we found that mitochondria are positioned near spines with orientation preferences that are dissimilar to the somatic preference. Additionally, we found that mitochondria are positioned near groups of spines with heterogeneous orientation preferences. For a subset of spines with mitochondrion in the head or neck, synapses were larger and exhibited greater selectivity to visual stimuli than those without a mitochondrion. Our data suggest mitochondria are not necessarily positioned to support the energy needs of strong spines, but rather support the structurally and functionally diverse inputs innervating the basal dendrites of cortical neurons.
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Affiliation(s)
- Connon I. Thomas
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, 1 Max Planck Way, Jupiter, FL 33458, USA
| | - Melissa A. Ryan
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, 1 Max Planck Way, Jupiter, FL 33458, USA
- Present Address: Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Naomi Kamasawa
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, 1 Max Planck Way, Jupiter, FL 33458, USA
| | - Benjamin Scholl
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, 415 Curie Blvd, Philadelphia, PA, 19104, USA
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6
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Michalska JM, Lyudchik J, Velicky P, Štefaničková H, Watson JF, Cenameri A, Sommer C, Amberg N, Venturino A, Roessler K, Czech T, Höftberger R, Siegert S, Novarino G, Jonas P, Danzl JG. Imaging brain tissue architecture across millimeter to nanometer scales. Nat Biotechnol 2023:10.1038/s41587-023-01911-8. [PMID: 37653226 DOI: 10.1038/s41587-023-01911-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 07/20/2023] [Indexed: 09/02/2023]
Abstract
Mapping the complex and dense arrangement of cells and their connectivity in brain tissue demands nanoscale spatial resolution imaging. Super-resolution optical microscopy excels at visualizing specific molecules and individual cells but fails to provide tissue context. Here we developed Comprehensive Analysis of Tissues across Scales (CATS), a technology to densely map brain tissue architecture from millimeter regional to nanometer synaptic scales in diverse chemically fixed brain preparations, including rodent and human. CATS uses fixation-compatible extracellular labeling and optical imaging, including stimulated emission depletion or expansion microscopy, to comprehensively delineate cellular structures. It enables three-dimensional reconstruction of single synapses and mapping of synaptic connectivity by identification and analysis of putative synaptic cleft regions. Applying CATS to the mouse hippocampal mossy fiber circuitry, we reconstructed and quantified the synaptic input and output structure of identified neurons. We furthermore demonstrate applicability to clinically derived human tissue samples, including formalin-fixed paraffin-embedded routine diagnostic specimens, for visualizing the cellular architecture of brain tissue in health and disease.
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Affiliation(s)
- Julia M Michalska
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Julia Lyudchik
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Philipp Velicky
- Institute of Science and Technology Austria, Klosterneuburg, Austria
- Core Facility Imaging, Medical University of Vienna, Vienna, Austria
| | - Hana Štefaničková
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Jake F Watson
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Alban Cenameri
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Christoph Sommer
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Nicole Amberg
- Department of Neurology, Division of Neuropathology and Neurochemistry, Medical University of Vienna, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | | | - Karl Roessler
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
- Department of Neurosurgery, Medical University of Vienna, Vienna, Austria
| | - Thomas Czech
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
- Department of Neurosurgery, Medical University of Vienna, Vienna, Austria
| | - Romana Höftberger
- Department of Neurology, Division of Neuropathology and Neurochemistry, Medical University of Vienna, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Sandra Siegert
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Gaia Novarino
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Peter Jonas
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Johann G Danzl
- Institute of Science and Technology Austria, Klosterneuburg, Austria.
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7
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Dixit D, Hallisey VM, Zhu EYS, Okuniewska M, Cadwell K, Chipuk JE, Axelrad JE, Schwab SR. Sphingosine 1-phosphate receptor 1 inhibition induces a pro-apoptotic signaling cascade in T cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.21.554104. [PMID: 37662380 PMCID: PMC10473648 DOI: 10.1101/2023.08.21.554104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Effective immunity requires a large, diverse naïve T cell repertoire circulating among lymphoid organs in search of antigen. Sphingosine 1-phosphate (S1P) and its receptor S1PR1 contribute by both directing T cell migration and supporting T cell survival. Here, we address how S1P enables T cell survival, and the implications for patients treated with S1PR1 antagonists. Contrary to expectations, we found that S1PR1 limits apoptosis by maintaining the appropriate balance of BCL2 family members via restraint of JNK activity. Interestingly, the same residues of S1PR1 that enable receptor internalization are required to prevent this pro-apoptotic cascade. Findings in mice were recapitulated in ulcerative colitis patients treated with the S1PR1 antagonist ozanimod, and the loss of naïve T cells limited B cell responses. Our findings highlight an unexpected effect of S1PR1 antagonists on the ability to mount immune responses within lymph nodes, beyond their effect on lymph node egress, and suggest both limitations and novel uses of this important class of drugs.
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8
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Bosch C. Looking at the Human Brain in Detail. Biol Psychiatry 2023; 94:285-287. [PMID: 37495332 DOI: 10.1016/j.biopsych.2023.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 06/13/2023] [Indexed: 07/28/2023]
Affiliation(s)
- Carles Bosch
- Sensory Circuits and Neurotechnology Laboratory, The Francis Crick Institute, London, United Kingdom.
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9
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Hayashi S, Ohno N, Knott G, Molnár Z. Correlative light and volume electron microscopy to study brain development. Microscopy (Oxf) 2023; 72:279-286. [PMID: 36620906 DOI: 10.1093/jmicro/dfad002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 01/06/2023] [Indexed: 01/10/2023] Open
Abstract
Recent advances in volume electron microscopy (EM) have been driving our thorough understanding of the brain architecture. Volume EM becomes increasingly powerful when cells and their subcellular structures that are imaged in light microscopy are correlated to those in ultramicrographs obtained with EM. This correlative approach, called correlative light and volume electron microscopy (vCLEM), is used to link three-dimensional ultrastructural information with physiological data such as intracellular Ca2+ dynamics. Genetic tools to express fluorescent proteins and/or an engineered form of a soybean ascorbate peroxidase allow us to perform vCLEM using natural landmarks including blood vessels without immunohistochemical staining. This immunostaining-free vCLEM has been successfully employed in two-photon Ca2+ imaging in vivo as well as in studying complex synaptic connections in thalamic neurons that receive a variety of specialized inputs from the cerebral cortex. In this mini-review, we overview how volume EM and vCLEM have contributed to studying the developmental processes of the brain. We also discuss potential applications of genetic manipulation of target cells using clustered regularly interspaced short palindromic repeats-associated protein 9 and subsequent volume EM to the analysis of protein localization as well as to loss-of-function studies of genes regulating brain development. We give examples for the combinatorial usage of genetic tools with vCLEM that will further enhance our understanding of regulatory mechanisms underlying brain development.
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Affiliation(s)
- Shuichi Hayashi
- Department of Anatomy, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama 701-0192, Japan
| | - Nobuhiko Ohno
- Department of Anatomy, Division of Histology and Cell Biology, School of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
- Division of Ultrastructural Research, National Institute for Physiological Sciences, 5-1 Higashiyama Myodaiji, Okazaki, Aichi 444-8787, Japan
| | - Graham Knott
- Biological Electron Microscopy Facility, Faculty of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Route Cantonale, Lausanne CH-1015, Switzerland
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
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10
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Spirou GA, Kersting M, Carr S, Razzaq B, Yamamoto Alves Pinto C, Dawson M, Ellisman MH, Manis PB. High-resolution volumetric imaging constrains compartmental models to explore synaptic integration and temporal processing by cochlear nucleus globular bushy cells. eLife 2023; 12:e83393. [PMID: 37288824 PMCID: PMC10435236 DOI: 10.7554/elife.83393] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 06/07/2023] [Indexed: 06/09/2023] Open
Abstract
Globular bushy cells (GBCs) of the cochlear nucleus play central roles in the temporal processing of sound. Despite investigation over many decades, fundamental questions remain about their dendrite structure, afferent innervation, and integration of synaptic inputs. Here, we use volume electron microscopy (EM) of the mouse cochlear nucleus to construct synaptic maps that precisely specify convergence ratios and synaptic weights for auditory nerve innervation and accurate surface areas of all postsynaptic compartments. Detailed biophysically based compartmental models can help develop hypotheses regarding how GBCs integrate inputs to yield their recorded responses to sound. We established a pipeline to export a precise reconstruction of auditory nerve axons and their endbulb terminals together with high-resolution dendrite, soma, and axon reconstructions into biophysically detailed compartmental models that could be activated by a standard cochlear transduction model. With these constraints, the models predict auditory nerve input profiles whereby all endbulbs onto a GBC are subthreshold (coincidence detection mode), or one or two inputs are suprathreshold (mixed mode). The models also predict the relative importance of dendrite geometry, soma size, and axon initial segment length in setting action potential threshold and generating heterogeneity in sound-evoked responses, and thereby propose mechanisms by which GBCs may homeostatically adjust their excitability. Volume EM also reveals new dendritic structures and dendrites that lack innervation. This framework defines a pathway from subcellular morphology to synaptic connectivity, and facilitates investigation into the roles of specific cellular features in sound encoding. We also clarify the need for new experimental measurements to provide missing cellular parameters, and predict responses to sound for further in vivo studies, thereby serving as a template for investigation of other neuron classes.
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Affiliation(s)
- George A Spirou
- Department of Medical Engineering, University of South FloridaTampaUnited States
| | - Matthew Kersting
- Department of Medical Engineering, University of South FloridaTampaUnited States
| | - Sean Carr
- Department of Medical Engineering, University of South FloridaTampaUnited States
| | - Bayan Razzaq
- Department of Otolaryngology, Head and Neck Surgery, West Virginia UniversityMorgantownUnited States
| | | | - Mariah Dawson
- Department of Otolaryngology, Head and Neck Surgery, West Virginia UniversityMorgantownUnited States
| | - Mark H Ellisman
- Department of Neurosciences, University of California, San DiegoSan DiegoUnited States
- National Center for Microscopy and Imaging Research,University of California, San DiegoSan DiegoUnited States
| | - Paul B Manis
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel HillChapel HillUnited States
- Department of Cell Biology and Physiology, University of North CarolinaChapel HillUnited States
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11
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Tamada H. Three-dimensional ultrastructure analysis of organelles in injured motor neuron. Anat Sci Int 2023:10.1007/s12565-023-00720-y. [PMID: 37071350 DOI: 10.1007/s12565-023-00720-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 03/23/2023] [Indexed: 04/19/2023]
Abstract
Morphological analysis of organelles is one of the important clues for understanding the cellular conditions and mechanisms occurring in cells. In particular, nanoscale information within crowded intracellular organelles of tissues provide more direct implications when compared to analyses of cells in culture or isolation. However, there are some difficulties in detecting individual shape using light microscopy, including super-resolution microscopy. Transmission electron microscopy (TEM), wherein the ultrastructure can be imaged at the membrane level, cannot determine the whole structure, and analyze it quantitatively. Volume EM, such as focused ion beam/scanning electron microscopy (FIB/SEM), can be a powerful tool to explore the details of three-dimensional ultrastructures even within a certain volume, and to measure several parameters from them. In this review, the advantages of FIB/SEM analysis in organelle studies are highlighted along with the introduction of mitochondrial analysis in injured motor neurons. This would aid in understanding the morphological details of mitochondria, especially those distributed in the cell bodies as well as in the axon initial segment (AIS) in mouse tissues. These regions have not been explored thus far due to the difficulties encountered in accessing their images by conditional microscopies. Some mechanisms of nerve regeneration have also been discussed with reference to the obtained findings. Finally, future perspectives on FIB/SEM are introduced. The combination of biochemical and genetic understanding of organelle structures and a nanoscale understanding of their three-dimensional distribution and morphology will help to match achievements in genomics and structural biology.
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Affiliation(s)
- Hiromi Tamada
- Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-Ku, Nagoya, Aichi, 466-8550, Japan.
- Anatomy, Graduate School of Medicines, University of Fukui, Matsuokashimoaizuki, Eiheiji-Cho, Yoshida-Gun, Fukui, 910-1193, Japan.
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Maher EE, Briegel AC, Imtiaz S, Fox MA, Golino H, Erisir A. 3D electron microscopy and volume-based bouton sorting reveal the selectivity of inputs onto geniculate relay cell and interneuron dendrite segments. Front Neuroanat 2023; 17:1150747. [PMID: 37007643 PMCID: PMC10064015 DOI: 10.3389/fnana.2023.1150747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 02/27/2023] [Indexed: 03/19/2023] Open
Abstract
Introduction The visual signals evoked at the retinal ganglion cells are modified and modulated by various synaptic inputs that impinge on lateral geniculate nucleus cells before they are sent to the cortex. The selectivity of geniculate inputs for clustering or forming microcircuits on discrete dendritic segments of geniculate cell types may provide the structural basis for network properties of the geniculate circuitry and differential signal processing through the parallel pathways of vision. In our study, we aimed to reveal the patterns of input selectivity on morphologically discernable relay cell types and interneurons in the mouse lateral geniculate nucleus. Methods We used two sets of Scanning Blockface Electron Microscopy (SBEM) image stacks and Reconstruct software to manually reconstruct of terminal boutons and dendrite segments. First, using an unbiased terminal sampling (UTS) approach and statistical modeling, we identified the criteria for volume-based sorting of geniculate boutons into their putative origins. Geniculate terminal boutons that were sorted in retinal and non-retinal categories based on previously described mitochondrial morphology, could further be sorted into multiple subpopulations based on their bouton volume distributions. Terminals deemed non-retinal based on the morphological criteria consisted of five distinct subpopulations, including small-sized putative corticothalamic and cholinergic boutons, two medium-sized putative GABAergic inputs, and a large-sized bouton type that contains dark mitochondria. Retinal terminals also consisted of four distinct subpopulations. The cutoff criteria for these subpopulations were then applied to datasets of terminals that synapse on reconstructed dendrite segments of relay cells or interneurons. Results Using a network analysis approach, we found an almost complete segregation of retinal and cortical terminals on putative X-type cell dendrite segments characterized by grape-like appendages and triads. On these cells, interneuron appendages intermingle with retinal and other medium size terminals to form triads within glomeruli. In contrast, a second, presumed Y-type cell displayed dendrodendritic puncta adherentia and received all terminal types without a selectivity for synapse location; these were not engaged in triads. Furthermore, the contribution of retinal and cortical synapses received by X-, Y- and interneuron dendrites differed such that over 60% of inputs to interneuron dendrites were from the retina, as opposed to 20% and 7% to X- and Y-type cells, respectively. Conclusion The results underlie differences in network properties of synaptic inputs from distinct origins on geniculate cell types.
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Affiliation(s)
- Erin E Maher
- Department of Psychology, University of Virginia, Charlottesville, VA, United States
| | - Alex C Briegel
- Department of Psychology, University of Virginia, Charlottesville, VA, United States
| | - Shahrozia Imtiaz
- Department of Psychology, University of Virginia, Charlottesville, VA, United States
| | - Michael A Fox
- School of Neuroscience, Virginia Tech, Blacksburg, VA, United States
- Fralin Biomedical Research Institute, Roanoke, VA, United States
| | - Hudson Golino
- Department of Psychology, University of Virginia, Charlottesville, VA, United States
| | - Alev Erisir
- Department of Psychology, University of Virginia, Charlottesville, VA, United States
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13
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Impact of Training Data, Ground Truth and Shape Variability in the Deep Learning-Based Semantic Segmentation of HeLa Cells Observed with Electron Microscopy. J Imaging 2023; 9:jimaging9030059. [PMID: 36976110 PMCID: PMC10058680 DOI: 10.3390/jimaging9030059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/16/2023] [Accepted: 02/17/2023] [Indexed: 03/06/2023] Open
Abstract
This paper investigates the impact of the amount of training data and the shape variability on the segmentation provided by the deep learning architecture U-Net. Further, the correctness of ground truth (GT) was also evaluated. The input data consisted of a three-dimensional set of images of HeLa cells observed with an electron microscope with dimensions 8192×8192×517. From there, a smaller region of interest (ROI) of 2000×2000×300 was cropped and manually delineated to obtain the ground truth necessary for a quantitative evaluation. A qualitative evaluation was performed on the 8192×8192 slices due to the lack of ground truth. Pairs of patches of data and labels for the classes nucleus, nuclear envelope, cell and background were generated to train U-Net architectures from scratch. Several training strategies were followed, and the results were compared against a traditional image processing algorithm. The correctness of GT, that is, the inclusion of one or more nuclei within the region of interest was also evaluated. The impact of the extent of training data was evaluated by comparing results from 36,000 pairs of data and label patches extracted from the odd slices in the central region, to 135,000 patches obtained from every other slice in the set. Then, 135,000 patches from several cells from the 8192×8192 slices were generated automatically using the image processing algorithm. Finally, the two sets of 135,000 pairs were combined to train once more with 270,000 pairs. As would be expected, the accuracy and Jaccard similarity index improved as the number of pairs increased for the ROI. This was also observed qualitatively for the 8192×8192 slices. When the 8192×8192 slices were segmented with U-Nets trained with 135,000 pairs, the architecture trained with automatically generated pairs provided better results than the architecture trained with the pairs from the manually segmented ground truths. This suggests that the pairs that were extracted automatically from many cells provided a better representation of the four classes of the various cells in the 8192×8192 slice than those pairs that were manually segmented from a single cell. Finally, the two sets of 135,000 pairs were combined, and the U-Net trained with these provided the best results.
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14
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Maruo T, Mizutani K, Miyata M, Kuriu T, Sakakibara S, Takahashi H, Kida D, Maesaka K, Sugaya T, Sakane A, Sasaki T, Takai Y, Mandai K. s-Afadin binds to MAGUIN/Cnksr2 and regulates the localization of the AMPA receptor and glutamatergic synaptic response in hippocampal neurons. J Biol Chem 2023; 299:103040. [PMID: 36803960 PMCID: PMC10040811 DOI: 10.1016/j.jbc.2023.103040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 02/02/2023] [Accepted: 02/03/2023] [Indexed: 02/19/2023] Open
Abstract
A hippocampal mossy fiber synapse implicated in learning and memory is a complex structure in which a presynaptic bouton attaches to the dendritic trunk by puncta adherentia junctions (PAJs) and wraps multiply branched spines. The postsynaptic densities (PSDs) are localized at the heads of each of these spines and faces to the presynaptic active zones. We previously showed that the scaffolding protein afadin regulates the formation of the PAJs, PSDs, and active zones in the mossy fiber synapse. Afadin has two splice variants: l-afadin and s-afadin. l-Afadin, but not s-afadin, regulates the formation of the PAJs but the roles of s-afadin in synaptogenesis remain unknown. We found here that s-afadin more preferentially bound to MAGUIN (a product of the Cnksr2 gene) than l-afadin in vivo and in vitro. MAGUIN/CNKSR2 is one of the causative genes for nonsyndromic X-linked intellectual disability accompanied by epilepsy and aphasia. Genetic ablation of MAGUIN impaired PSD-95 localization and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic (AMPA) receptor surface accumulation in cultured hippocampal neurons. Our electrophysiological analysis revealed that the postsynaptic response to glutamate, but not its release from the presynapse, was impaired in the MAGUIN-deficient cultured hippocampal neurons. Furthermore, disruption of MAGUIN did not increase the seizure susceptibility to flurothyl, a GABAA receptor antagonist. These results indicate that s-afadin binds to MAGUIN and regulates the PSD-95-dependent cell surface localization of the AMPA receptor and glutamatergic synaptic responses in the hippocampal neurons and that MAGUIN is not involved in the induction of epileptic seizure by flurothyl in our mouse model.
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Affiliation(s)
- Tomohiko Maruo
- Department of Molecular and Cellular Neurobiology, Kitasato University Graduate School of Medical Sciences, Sagamihara, Kanagawa, Japan; Department of Biochemistry, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan; Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan; Department of Biochemistry, Tokushima University Graduate School of Medical Sciences, Tokushima, Japan
| | - Kiyohito Mizutani
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
| | - Muneaki Miyata
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
| | - Toshihiko Kuriu
- Research and Development Center, Osaka Medical and Pharmaceutical University, Takatsuki, Osaka, Japan
| | - Shotaro Sakakibara
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan; Department of Biochemistry, Tokushima University Graduate School of Medical Sciences, Tokushima, Japan
| | - Hatena Takahashi
- Department of Molecular and Cellular Neurobiology, Kitasato University Graduate School of Medical Sciences, Sagamihara, Kanagawa, Japan
| | - Daichi Kida
- Department of Molecular and Cellular Neurobiology, Kitasato University Graduate School of Medical Sciences, Sagamihara, Kanagawa, Japan
| | - Kouki Maesaka
- Department of Molecular and Cellular Neurobiology, Kitasato University Graduate School of Medical Sciences, Sagamihara, Kanagawa, Japan
| | - Tsukiko Sugaya
- Department of Biochemistry, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Ayuko Sakane
- Department of Biochemistry, Tokushima University Graduate School of Medical Sciences, Tokushima, Japan; Department of Interdisciplinary Researches for Medicine and Photonics, Institute of Post-LED Photonics, Tokushima University, Tokushima, Japan
| | - Takuya Sasaki
- Department of Biochemistry, Tokushima University Graduate School of Medical Sciences, Tokushima, Japan
| | - Yoshimi Takai
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan.
| | - Kenji Mandai
- Department of Molecular and Cellular Neurobiology, Kitasato University Graduate School of Medical Sciences, Sagamihara, Kanagawa, Japan; Department of Biochemistry, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
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15
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Mironov AA, Beznoussenko GV. Algorithm for Modern Electron Microscopic Examination of the Golgi Complex. Methods Mol Biol 2022; 2557:161-209. [PMID: 36512216 DOI: 10.1007/978-1-0716-2639-9_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The Golgi complex (GC) is an essential organelle of the eukaryotic exocytic pathway. It has a very complexed structure and thus localization of its resident proteins is not trivial. Fast development of microscopic methods generates a huge difficulty for Golgi researchers to select the best protocol to use. Modern methods of light microscopy, such as super-resolution light microscopy (SRLM) and electron microscopy (EM), open new possibilities in analysis of various biological structures at organelle, cell, and organ levels. Nowadays, new generation of EM methods became available for the study of the GC; these include three-dimensional EM (3DEM), correlative light-EM (CLEM), immune EM, and new estimators within stereology that allow realization of maximal goal of any morphological study, namely, to achieve a three-dimensional model of the sample with optimal level of resolution and quantitative determination of its chemical composition. Methods of 3DEM have partially overlapping capabilities. This requires a careful comparison of these methods, identification of their strengths and weaknesses, and formulation of recommendations for their application to cell or tissue samples. Here, we present an overview of 3DEM methods for the study of the GC and some basics for how the images are formed and how the image quality can be improved.
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16
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Lichter K, Paul MM, Pauli M, Schoch S, Kollmannsberger P, Stigloher C, Heckmann M, Sirén AL. Ultrastructural analysis of wild-type and RIM1α knockout active zones in a large cortical synapse. Cell Rep 2022; 40:111382. [PMID: 36130490 DOI: 10.1016/j.celrep.2022.111382] [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: 03/04/2022] [Revised: 06/14/2022] [Accepted: 08/28/2022] [Indexed: 11/18/2022] Open
Abstract
Rab3A-interacting molecule (RIM) is crucial for fast Ca2+-triggered synaptic vesicle (SV) release in presynaptic active zones (AZs). We investigated hippocampal giant mossy fiber bouton (MFB) AZ architecture in 3D using electron tomography of rapid cryo-immobilized acute brain slices in RIM1α-/- and wild-type mice. In RIM1α-/-, AZs are larger with increased synaptic cleft widths and a 3-fold reduced number of tightly docked SVs (0-2 nm). The distance of tightly docked SVs to the AZ center is increased from 110 to 195 nm, and the width of their electron-dense material between outer SV membrane and AZ membrane is reduced. Furthermore, the SV pool in RIM1α-/- is more heterogeneous. Thus, RIM1α, besides its role in tight SV docking, is crucial for synaptic architecture and vesicle pool organization in MFBs.
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Affiliation(s)
- Katharina Lichter
- Department of Neurosurgery, University Hospital of Würzburg, 97080 Würzburg, Germany; Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany; Center of Mental Health, Department of Psychiatry, Psychosomatics and Psychotherapy, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Mila Marie Paul
- Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany; Department of Orthopedic Trauma, Hand, Plastic and Reconstructive Surgery, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Martin Pauli
- Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany
| | - Susanne Schoch
- Department of Neuropathology and Department of Epileptology, University Hospital Bonn, 53127 Bonn, Germany
| | - Philip Kollmannsberger
- Center for Computational and Theoretical Biology, Julius-Maximilians-University Würzburg, 97074 Würzburg, Germany
| | - Christian Stigloher
- Imaging Core Facility, Biocenter, University of Würzburg, 97074 Würzburg, Germany.
| | - Manfred Heckmann
- Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany.
| | - Anna-Leena Sirén
- Department of Neurosurgery, University Hospital of Würzburg, 97080 Würzburg, Germany; Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany.
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17
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Albargothy MJ, Azizah NN, Stewart SL, Troendle EP, Steel DHW, Curtis TM, Taggart MJ. Investigation of heterocellular features of the mouse retinal neurovascular unit by 3D electron microscopy. J Anat 2022. [PMID: 35841597 DOI: 10.1111/joa.13721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 06/06/2022] [Accepted: 06/15/2022] [Indexed: 11/26/2022] Open
Abstract
The retina has a complex structure with a diverse collection of component cells that work together to facilitate vision. The retinal capillaries supplying the nutritional requirements to the inner retina have an intricate system of neural, glial and vascular elements that interconnect to form the neurovascular unit (NVU). The retina has no autonomic nervous system and so relies on the NVU as an interdependent, physical and functional unit to alter blood flow appropriately to changes in the physiological environment. The importance of this is demonstrated by alterations in NVU function being apparent in the blinding disease diabetic retinopathy and other diseases of the retina. It is, therefore, imperative to understand the anatomy of the components of the NVU that underlie its functioning and in particular the nanoscale arrangements of its heterocellular components. However, information on this in three spatial dimensions is limited. In the present study, we utilised the technique of serial block-face scanning electron microscopy (SBF-SEM), and computational image reconstruction, to enable the first three-dimensional ultrastructural analysis of the NVU in mouse retinal capillaries. Mouse isolated retina was prepared for SBF-SEM and up to 150 serial scanning electron microscopy images (covering z-axes distances of 12-8 mm) of individual capillaries in the superficial plexus and NVU cellular components digitally aligned. Examination of the data in the x-, y- and z-planes was performed with the use of semi-automated computational image analysis tools including segmentation, 3D image reconstruction and quantitation of cell proximities. A prominent feature of the capillary arrangements in 3D was the extensive sheath-like coverage by singular pericytes. They appeared in close register to the basement membrane with which they interwove in a complex mesh-like appearance. Breaks in the basement membrane appeared to facilitate pericyte interactions with other NVU cell types. There were frequent, close (<10 nm) pericyte-endothelial interactions with direct contact points and peg-and-socket-like morphology. Macroglia typically intervened between neurons and capillary structures; however, regions were identified where neurons came into closer contact with the basement membrane. A software-generated analysis to assess the morphology of the different cellular components of the NVU, including quantifications of convexity, sphericity and cell-to-cell closeness, has enabled preliminary semi-quantitative characterisation of cell arrangements with neighbouring structures. This study presents new data on the nanoscale spatial characteristics of components of the murine retinal NVU in 3D that has implications for our understanding of structural integrity (e.g. pericyte-endothelial cell anchoring) and function (e.g. possible paracrine communication between macroglia and pericytes). It also serves as a platform to inform future studies examining changes in NVU characteristics with different biological and disease circumstances. All raw and processed image data have been deposited for public viewing.
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Affiliation(s)
- Mona J Albargothy
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Nadhira N Azizah
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Sarah L Stewart
- Wellcome Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, UK
| | - Evan P Troendle
- Wellcome Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, UK
| | - David H W Steel
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Tim M Curtis
- Wellcome Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, UK
| | - Michael J Taggart
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
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18
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Zhang Y, Ackels T, Pacureanu A, Zdora MC, Bonnin A, Schaefer AT, Bosch C. Sample Preparation and Warping Accuracy for Correlative Multimodal Imaging in the Mouse Olfactory Bulb Using 2-Photon, Synchrotron X-Ray and Volume Electron Microscopy. Front Cell Dev Biol 2022; 10:880696. [PMID: 35756997 PMCID: PMC9213878 DOI: 10.3389/fcell.2022.880696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 04/22/2022] [Indexed: 11/23/2022] Open
Abstract
Integrating physiology with structural insights of the same neuronal circuit provides a unique approach to understanding how the mammalian brain computes information. However, combining the techniques that provide both streams of data represents an experimental challenge. When studying glomerular column circuits in the mouse olfactory bulb, this approach involves e.g., recording the neuronal activity with in vivo 2-photon (2P) calcium imaging, retrieving the circuit structure with synchrotron X-ray computed tomography with propagation-based phase contrast (SXRT) and/or serial block-face scanning electron microscopy (SBEM) and correlating these datasets. Sample preparation and dataset correlation are two key bottlenecks in this correlative workflow. Here, we first quantify the occurrence of different artefacts when staining tissue slices with heavy metals to generate X-ray or electron contrast. We report improvements in the staining procedure, ultimately achieving perfect staining in ∼67% of the 0.6 mm thick olfactory bulb slices that were previously imaged in vivo with 2P. Secondly, we characterise the accuracy of the spatial correlation between functional and structural datasets. We demonstrate that direct, single-cell precise correlation between in vivo 2P and SXRT tissue volumes is possible and as reliable as correlating between 2P and SBEM. Altogether, these results pave the way for experiments that require retrieving physiology, circuit structure and synaptic signatures in targeted regions. These correlative function-structure studies will bring a more complete understanding of mammalian olfactory processing across spatial scales and time.
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Affiliation(s)
- Yuxin Zhang
- Sensory Circuits and Neurotechnology Lab, The Francis Crick Institute, London, United Kingdom
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Tobias Ackels
- Sensory Circuits and Neurotechnology Lab, The Francis Crick Institute, London, United Kingdom
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Alexandra Pacureanu
- Sensory Circuits and Neurotechnology Lab, The Francis Crick Institute, London, United Kingdom
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
- ESRF, The European Synchrotron, Grenoble, France
| | - Marie-Christine Zdora
- Department of Physics and Astronomy, University College London, London, United Kingdom
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, United Kingdom
- School of Physics and Astronomy, University of Southampton, Highfield Campus, Southampton, United Kingdom
- Paul Scherrer Institut, Villigen, Switzerland
| | - Anne Bonnin
- Paul Scherrer Institut, Villigen, Switzerland
| | - Andreas T. Schaefer
- Sensory Circuits and Neurotechnology Lab, The Francis Crick Institute, London, United Kingdom
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Carles Bosch
- Sensory Circuits and Neurotechnology Lab, The Francis Crick Institute, London, United Kingdom
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19
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Flores CC, Loschky SS, Marshall W, Spano GM, Massaro Cenere M, Tononi G, Cirelli C. Identification of ultrastructural signatures of sleep and wake in the fly brain. Sleep 2022; 45:zsab235. [PMID: 35554595 PMCID: PMC9113029 DOI: 10.1093/sleep/zsab235] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 07/12/2021] [Indexed: 11/14/2022] Open
Abstract
The cellular consequences of sleep loss are poorly characterized. In the pyramidal neurons of mouse frontal cortex, we found that mitochondria and secondary lysosomes occupy a larger proportion of the cytoplasm after chronic sleep restriction compared to sleep, consistent with increased cellular burden due to extended wake. For each morphological parameter, the within-animal variance was high, suggesting that the effects of sleep and sleep loss vary greatly among neurons. However, the analysis was based on 4-5 mice/group and a single section/cell. Here, we applied serial block-face scanning electron microscopy to identify signatures of sleep and sleep loss in the Drosophila brain. Stacks of images were acquired and used to obtain full 3D reconstructions of the cytoplasm and nucleus of 263 Kenyon cells from adult flies collected after a night of sleep (S) or after 11 h (SD11) or 35 h (SD35) of sleep deprivation (9 flies/group). Relative to S flies, SD35 flies showed increased density of dark clusters of chromatin and Golgi apparata and a trend increase in the percent of cell volume occupied by mitochondria, consistent with increased need for energy and protein supply during extended wake. Logistic regression models could assign each neuron to the correct experimental group with good accuracy, but in each cell, nuclear and cytoplasmic changes were poorly correlated, and within-fly variance was substantial in all experimental groups. Together, these results support the presence of ultrastructural signatures of sleep and sleep loss but underscore the complexity of their effects at the single-cell level.
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Affiliation(s)
- Carlos C Flores
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI, USA
| | - Sophia S Loschky
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI, USA
| | - William Marshall
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI, USA
- Department of Mathematics and Statistics, Brock University, St. Catharines, ON, Canada
| | | | | | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI, USA
| | - Chiara Cirelli
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI, USA
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20
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Mito T, Vincent AE, Faitg J, Taylor RW, Khan NA, McWilliams TG, Suomalainen A. Mosaic dysfunction of mitophagy in mitochondrial muscle disease. Cell Metab 2022; 34:197-208.e5. [PMID: 35030325 PMCID: PMC8815775 DOI: 10.1016/j.cmet.2021.12.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 10/12/2021] [Accepted: 12/17/2021] [Indexed: 01/07/2023]
Abstract
Mitophagy is a quality control mechanism that eliminates damaged mitochondria, yet its significance in mammalian pathophysiology and aging has remained unclear. Here, we report that mitophagy contributes to mitochondrial dysfunction in skeletal muscle of aged mice and human patients. The early disease stage is characterized by muscle fibers with central nuclei, with enhanced mitophagy around these nuclei. However, progressive mitochondrial dysfunction halts mitophagy and disrupts lysosomal homeostasis. Interestingly, activated or halted mitophagy occur in a mosaic manner even in adjacent muscle fibers, indicating cell-autonomous regulation. Rapamycin restores mitochondrial turnover, indicating mTOR-dependence of mitochondrial recycling in advanced disease stage. Our evidence suggests that (1) mitophagy is a hallmark of age-related mitochondrial pathology in mammalian muscle, (2) mosaic halting of mitophagy is a mechanism explaining mosaic respiratory chain deficiency and accumulation of pathogenic mtDNA variants in adult-onset mitochondrial diseases and normal aging, and (3) augmenting mitophagy is a promising therapeutic approach for muscle mitochondrial dysfunction.
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Affiliation(s)
- Takayuki Mito
- Research Program of Stem Cells and Metabolism, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland
| | - Amy E Vincent
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Julie Faitg
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK
| | - Nahid A Khan
- Research Program of Stem Cells and Metabolism, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland
| | - Thomas G McWilliams
- Research Program of Stem Cells and Metabolism, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland; Department of Anatomy, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Anu Suomalainen
- Research Program of Stem Cells and Metabolism, Faculty of Medicine, Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland; Helsinki University Hospital, HUSlab, 00290 Helsinki, Finland.
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21
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Kim J, Park D, Seo NY, Yoon TH, Kim GH, Lee SH, Seo J, Um JW, Lee KJ, Ko J. LRRTM3 regulates activity-dependent synchronization of synapse properties in topographically connected hippocampal neural circuits. Proc Natl Acad Sci U S A 2022; 119:e2110196119. [PMID: 35022233 PMCID: PMC8784129 DOI: 10.1073/pnas.2110196119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Accepted: 12/03/2021] [Indexed: 11/18/2022] Open
Abstract
Synaptic cell-adhesion molecules (CAMs) organize the architecture and properties of neural circuits. However, whether synaptic CAMs are involved in activity-dependent remodeling of specific neural circuits is incompletely understood. Leucine-rich repeat transmembrane protein 3 (LRRTM3) is required for the excitatory synapse development of hippocampal dentate gyrus (DG) granule neurons. Here, we report that Lrrtm3-deficient mice exhibit selective reductions in excitatory synapse density and synaptic strength in projections involving the medial entorhinal cortex (MEC) and DG granule neurons, accompanied by increased neurotransmitter release and decreased excitability of granule neurons. LRRTM3 deletion significantly reduced excitatory synaptic innervation of hippocampal mossy fibers (Mf) of DG granule neurons onto thorny excrescences in hippocampal CA3 neurons. Moreover, LRRTM3 loss in DG neurons significantly decreased mossy fiber long-term potentiation (Mf-LTP). Remarkably, silencing MEC-DG circuits protected against the decrease in the excitatory synaptic inputs onto DG and CA3 neurons, excitability of DG granule neurons, and Mf-LTP in Lrrtm3-deficient mice. These results suggest that LRRTM3 may be a critical factor in activity-dependent synchronization of the topography of MEC-DG-CA3 excitatory synaptic connections. Collectively, our data propose that LRRTM3 shapes the target-specific structural and functional properties of specific hippocampal circuits.
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Affiliation(s)
- Jinhu Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Dongseok Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Na-Young Seo
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
- Neural Circuits Group, Korea Brain Research Institute (KBRI), Daegu 41062, Korea
| | - Taek-Han Yoon
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Gyu Hyun Kim
- Neural Circuits Group, Korea Brain Research Institute (KBRI), Daegu 41062, Korea
| | - Sang-Hoon Lee
- Neural Circuits Group, Korea Brain Research Institute (KBRI), Daegu 41062, Korea
- Brain Research Core Facilities, KBRI, Daegu 41062, Korea
| | - Jinsoo Seo
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Kea Joo Lee
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
- Neural Circuits Group, Korea Brain Research Institute (KBRI), Daegu 41062, Korea
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
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22
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Loschky SS, Spano GM, Marshall W, Schroeder A, Nemec KM, Schiereck SS, de Vivo L, Bellesi M, Banningh SW, Tononi G, Cirelli C. Ultrastructural effects of sleep and wake on the parallel fiber synapses of the cerebellum. eLife 2022; 11:84199. [PMID: 36576248 PMCID: PMC9797193 DOI: 10.7554/elife.84199] [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: 10/13/2022] [Accepted: 12/18/2022] [Indexed: 12/29/2022] Open
Abstract
Multiple evidence in rodents shows that the strength of excitatory synapses in the cerebral cortex and hippocampus is greater after wake than after sleep. The widespread synaptic weakening afforded by sleep is believed to keep the cost of synaptic activity under control, promote memory consolidation, and prevent synaptic saturation, thus preserving the brain's ability to learn day after day. The cerebellum is highly plastic and the Purkinje cells, the sole output neurons of the cerebellar cortex, are endowed with a staggering number of excitatory parallel fiber synapses. However, whether these synapses are affected by sleep and wake is unknown. Here, we used serial block face scanning electron microscopy to obtain the full 3D reconstruction of more than 7000 spines and their parallel fiber synapses in the mouse posterior vermis. This analysis was done in mice whose cortical and hippocampal synapses were previously measured, revealing that average synaptic size was lower after sleep compared to wake with no major changes in synapse number. Here, instead, we find that while the average size of parallel fiber synapses does not change, the number of branched synapses is reduced in half after sleep compared to after wake, corresponding to ~16% of all spines after wake and ~8% after sleep. Branched synapses are harbored by two or more spines sharing the same neck and, as also shown here, are almost always contacted by different parallel fibers. These findings suggest that during wake, coincidences of firing over parallel fibers may translate into the formation of synapses converging on the same branched spine, which may be especially effective in driving Purkinje cells to fire. By contrast, sleep may promote the off-line pruning of branched synapses that were formed due to spurious coincidences.
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Affiliation(s)
- Sophia S Loschky
- Department of Psychiatry, University of Wisconsin-MadisonMadisonUnited States
| | | | - William Marshall
- Department of Psychiatry, University of Wisconsin-MadisonMadisonUnited States,Department of Mathematics and Statistics, Brock UniversitySt. CatharinesCanada
| | - Andrea Schroeder
- Department of Psychiatry, University of Wisconsin-MadisonMadisonUnited States
| | - Kelsey Marie Nemec
- Department of Psychiatry, University of Wisconsin-MadisonMadisonUnited States
| | | | - Luisa de Vivo
- Department of Psychiatry, University of Wisconsin-MadisonMadisonUnited States
| | - Michele Bellesi
- Department of Psychiatry, University of Wisconsin-MadisonMadisonUnited States
| | | | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin-MadisonMadisonUnited States
| | - Chiara Cirelli
- Department of Psychiatry, University of Wisconsin-MadisonMadisonUnited States
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23
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Tanaka M, Sakaba T, Miki T. Quantal analysis estimates docking site occupancy determining short-term depression at hippocampal glutamatergic synapses. J Physiol 2021; 599:5301-5327. [PMID: 34705277 DOI: 10.1113/jp282235] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/20/2021] [Indexed: 12/23/2022] Open
Abstract
Before fusion, synaptic vesicles (SVs) pause at discrete release/docking sites. During repetitive stimulation, the probability of site occupancy changes following SV fusion and replenishment. The occupancy probability is considered to be one of the crucial determinants of synaptic strength, but it is difficult to estimate separately because it usually blends with other synaptic parameters. Thus, the contribution of site occupancy to synaptic function, particularly to synaptic depression, remains elusive. Here, we directly estimated the occupancy probability at the hippocampal mossy fibre-CA3 interneuron synapse showing synaptic depression, using statistics of counts of vesicular events detected by deconvolution. We found that this synapse had a particularly high occupancy (∼0.85) with a high release probability of a docked SV (∼0.8) under 3 mm external calcium conditions. Analyses of quantal amplitudes and SV counts indicated that quantal size reduction decreased the amplitudes of all responses in a train to a similar degree, whereas release/docking site number was unchanged during trains, suggesting that quantal size and release/docking site number had little influence on the extent of synaptic depression. Model simulations revealed that the initial occupancy with high release probability and slow replenishment determined the time course of synaptic depression. Consistently, decreasing external calcium concentration reduced both the occupancy and release probability, and the reductions in turn produced less depression. Based on these results, we suggest that the occupancy probability is a crucial determinant of short-term synaptic depression at glutamatergic synapses in the hippocampus. KEY POINTS: The occupancy probability of a release/docking site by a synaptic vesicle at presynaptic terminals is considered to be one of the crucial determinants of synaptic strength, but it is difficult to estimate separately from other synaptic parameters. Here, we directly estimate the occupancy probability at the hippocampal mossy fibre-interneuron synapse using statistics of vesicular events detected by deconvolution. We show that the synapses have particularly high occupancy (0.85) with high release probability (0.8) under high external calcium concentration ([Ca2+ ]o ) conditions, and that both parameter values change with [Ca2+ ]o , shaping synaptic depression. Analyses of the quantal amplitudes and synaptic vesicle counts suggest that quantal sizes and release/docking site number have little influence on the extent of synaptic depression. The results suggest that the occupancy probability is a crucial determinant of short-term synaptic depression at glutamatergic synapses in the hippocampus.
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Affiliation(s)
- Mamoru Tanaka
- Graduate School of Brain Science, Doshisha University, Kyoto, Japan
| | - Takeshi Sakaba
- Graduate School of Brain Science, Doshisha University, Kyoto, Japan
| | - Takafumi Miki
- Graduate School of Brain Science, Doshisha University, Kyoto, Japan.,Organization for Research Initiatives and Development, Doshisha University, Kyoto, Japan
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24
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Zhuang A, Yap FYT, Borg DJ, McCarthy D, Fotheringham A, Leung S, Penfold SA, Sourris KC, Coughlan MT, Schulz BL, Forbes JM. The AGE receptor, OST48 drives podocyte foot process effacement and basement membrane expansion (alters structural composition). Endocrinol Diabetes Metab 2021; 4:e00278. [PMID: 34277994 PMCID: PMC8279619 DOI: 10.1002/edm2.278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 05/16/2021] [Accepted: 05/22/2021] [Indexed: 11/17/2022] Open
Abstract
AIMS The accumulation of advanced glycation end products is implicated in the development and progression of diabetic kidney disease. No study has examined whether stimulating advanced glycation clearance via receptor manipulation is reno-protective in diabetes. Podocytes, which are early contributors to diabetic kidney disease and could be a target for reno-protection. MATERIALS AND METHODS To examine the effects of increased podocyte oligosaccharyltransferase-48 on kidney function, glomerular sclerosis, tubulointerstitial fibrosis and proteome (PXD011434), we generated a mouse with increased oligosaccharyltransferase-48kDa subunit abundance in podocytes driven by the podocin promoter. RESULTS Despite increased urinary clearance of advanced glycation end products, we observed a decline in renal function, significant glomerular damage including glomerulosclerosis, collagen IV deposition, glomerular basement membrane thickening and foot process effacement and tubulointerstitial fibrosis. Analysis of isolated glomeruli identified enrichment in proteins associated with collagen deposition, endoplasmic reticulum stress and oxidative stress. Ultra-resolution microscopy of podocytes revealed denudation of foot processes where there was co-localization of oligosaccharyltransferase-48kDa subunit and advanced glycation end-products. CONCLUSIONS These studies indicate that increased podocyte expression of oligosaccharyltransferase-48 kDa subunit results in glomerular endoplasmic reticulum stress and a decline in kidney function.
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Affiliation(s)
- Aowen Zhuang
- Glycation and Diabetes ComplicationsMater Research Institute – The University of QueenslandTranslational Research InstituteWoolloongabbaQldAustralia
- Faculty of MedicineUniversity of QueenslandSt LuciaQldAustralia
- Baker Heart and Diabetes InstituteMelbourneVicAustralia
| | | | - Danielle J. Borg
- Glycation and Diabetes ComplicationsMater Research Institute – The University of QueenslandTranslational Research InstituteWoolloongabbaQldAustralia
| | - Domenica McCarthy
- Glycation and Diabetes ComplicationsMater Research Institute – The University of QueenslandTranslational Research InstituteWoolloongabbaQldAustralia
| | - Amelia Fotheringham
- Glycation and Diabetes ComplicationsMater Research Institute – The University of QueenslandTranslational Research InstituteWoolloongabbaQldAustralia
| | - Sherman Leung
- Glycation and Diabetes ComplicationsMater Research Institute – The University of QueenslandTranslational Research InstituteWoolloongabbaQldAustralia
| | | | - Karly C. Sourris
- Baker Heart and Diabetes InstituteMelbourneVicAustralia
- Department of DiabetesCentral Clinical SchoolMonash UniversityMelbourneVicAustralia
| | - Melinda T. Coughlan
- Baker Heart and Diabetes InstituteMelbourneVicAustralia
- Department of DiabetesCentral Clinical SchoolMonash UniversityMelbourneVicAustralia
| | - Benjamin L. Schulz
- School of Chemistry and Molecular BiosciencesUniversity of QueenslandSt LuciaQldAustralia
| | - Josephine M. Forbes
- Glycation and Diabetes ComplicationsMater Research Institute – The University of QueenslandTranslational Research InstituteWoolloongabbaQldAustralia
- Faculty of MedicineUniversity of QueenslandSt LuciaQldAustralia
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25
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Abstract
In this work, an unsupervised volumetric semantic instance segmentation of the plasma membrane of HeLa cells as observed with serial block face scanning electron microscopy is described. The resin background of the images was segmented at different slices of a 3D stack of 518 slices with 8192 × 8192 pixels each. The background was used to create a distance map, which helped identify and rank the cells by their size at each slice. The centroids of the cells detected at different slices were linked to identify them as a single cell that spanned a number of slices. A subset of these cells, i.e., the largest ones and those not close to the edges were selected for further processing. The selected cells were then automatically cropped to smaller regions of interest of 2000 × 2000 × 300 voxels that were treated as cell instances. Then, for each of these volumes, the nucleus was segmented, and the cell was separated from any neighbouring cells through a series of traditional image processing steps that followed the plasma membrane. The segmentation process was repeated for all the regions of interest previously selected. For one cell for which the ground truth was available, the algorithm provided excellent results in Accuracy (AC) and the Jaccard similarity Index (JI): nucleus: JI =0.9665, AC =0.9975, cell including nucleus JI =0.8711, AC =0.9655, cell excluding nucleus JI =0.8094, AC =0.9629. A limitation of the algorithm for the plasma membrane segmentation was the presence of background. In samples with tightly packed cells, this may not be available. When tested for these conditions, the segmentation of the nuclear envelope was still possible. All the code and data were released openly through GitHub, Zenodo and EMPIAR.
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26
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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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27
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CAPS1 is involved in hippocampal synaptic plasticity and hippocampus-associated learning. Sci Rep 2021; 11:8656. [PMID: 33883618 PMCID: PMC8060421 DOI: 10.1038/s41598-021-88009-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 04/07/2021] [Indexed: 12/14/2022] Open
Abstract
Calcium-dependent activator protein for secretion 1 (CAPS1) is a key molecule in vesicular exocytosis, probably in the priming step. However, CAPS1's role in synaptic plasticity and brain function is elusive. Herein, we showed that synaptic plasticity and learning behavior were impaired in forebrain and/or hippocampus-specific Caps1 conditional knockout (cKO) mice by means of molecular, physiological, and behavioral analyses. Neonatal Caps1 cKO mice showed a decrease in the number of docked vesicles in the hippocampal CA3 region, with no detectable changes in the distribution of other major exocytosis-related molecules. Additionally, long-term potentiation (LTP) was partially and severely impaired in the CA1 and CA3 regions, respectively. CA1 LTP was reinforced by repeated high-frequency stimuli, whereas CA3 LTP was completely abolished. Accordingly, hippocampus-associated learning was severely impaired in adeno-associated virus (AAV) infection-mediated postnatal Caps1 cKO mice. Collectively, our findings suggest that CAPS1 is a key protein involved in the cellular mechanisms underlying hippocampal synaptic release and plasticity, which is crucial for hippocampus-associated learning.
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28
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Hayashi S, Hoerder-Suabedissen A, Kiyokage E, Maclachlan C, Toida K, Knott G, Molnár Z. Maturation of Complex Synaptic Connections of Layer 5 Cortical Axons in the Posterior Thalamic Nucleus Requires SNAP25. Cereb Cortex 2021; 31:2625-2638. [PMID: 33367517 PMCID: PMC8023812 DOI: 10.1093/cercor/bhaa379] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 11/16/2020] [Accepted: 11/19/2020] [Indexed: 02/06/2023] Open
Abstract
Synapses are able to form in the absence of neuronal activity, but how is their subsequent maturation affected in the absence of regulated vesicular release? We explored this question using 3D electron microscopy and immunoelectron microscopy analyses in the large, complex synapses formed between cortical sensory efferent axons and dendrites in the posterior thalamic nucleus. Using a Synaptosome-associated protein 25 conditional knockout (Snap25 cKO), we found that during the first 2 postnatal weeks the axonal boutons emerge and increase in the size similar to the control animals. However, by P18, when an adult-like architecture should normally be established, axons were significantly smaller with 3D reconstructions, showing that each Snap25 cKO bouton only forms a single synapse with the connecting dendritic shaft. No excrescences from the dendrites were formed, and none of the normally large glomerular axon endings were seen. These results show that activity mediated through regulated vesicular release from the presynaptic terminal is not necessary for the formation of synapses, but it is required for the maturation of the specialized synaptic structures between layer 5 corticothalamic projections in the posterior thalamic nucleus.
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Affiliation(s)
- Shuichi Hayashi
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
- Department of Anatomy, Kawasaki Medical School, Kurashiki, Okayama 701-0192, Japan
| | - Anna Hoerder-Suabedissen
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Emi Kiyokage
- Department of Medical Technology, Kawasaki University of Medical Welfare, Kurashiki, Okayama 701-0193, Japan
| | - Catherine Maclachlan
- BioEM Facility, School of Life Sciences, EPFL, Lausanne 1015, Switzerland
- The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Kazunori Toida
- Department of Anatomy, Kawasaki Medical School, Kurashiki, Okayama 701-0192, Japan
- Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - Graham Knott
- BioEM Facility, School of Life Sciences, EPFL, Lausanne 1015, Switzerland
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
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29
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Courson JA, Landry PT, Do T, Spehlmann E, Lafontant PJ, Patel N, Rumbaut RE, Burns AR. Serial Block-Face Scanning Electron Microscopy (SBF-SEM) of Biological Tissue Samples. J Vis Exp 2021:10.3791/62045. [PMID: 33843931 PMCID: PMC8225236 DOI: 10.3791/62045] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Serial block-face scanning electron microscopy (SBF-SEM) allows for the collection of hundreds to thousands of serially-registered ultrastructural images, offering an unprecedented three-dimensional view of tissue microanatomy. While SBF-SEM has seen an exponential increase in use in recent years, technical aspects such as proper tissue preparation and imaging parameters are paramount for the success of this imaging modality. This imaging system benefits from the automated nature of the device, allowing one to leave the microscope unattended during the imaging process, with the automated collection of hundreds of images possible in a single day. However, without appropriate tissue preparation cellular ultrastructure can be altered in such a way that incorrect or misleading conclusions might be drawn. Additionally, images are generated by scanning the block-face of a resin-embedded biological sample and this often presents challenges and considerations that must be addressed. The accumulation of electrons within the block during imaging, known as "tissue charging," can lead to a loss of contrast and an inability to appreciate cellular structure. Moreover, while increasing electron beam intensity/voltage or decreasing beam-scanning speed can increase image resolution, this can also have the unfortunate side effect of damaging the resin block and distorting subsequent images in the imaging series. Here we present a routine protocol for the preparation of biological tissue samples that preserves cellular ultrastructure and diminishes tissue charging. We also provide imaging considerations for the rapid acquisition of high-quality serial-images with minimal damage to the tissue block.
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Affiliation(s)
- Justin A. Courson
- University of Houston, College of Optometry, Houston, TX,
United States of America
| | - Paul T. Landry
- University of Houston, College of Optometry, Houston, TX,
United States of America
| | - Thao Do
- University of Houston, College of Optometry, Houston, TX,
United States of America
| | - Eric Spehlmann
- DePauw University, Department of Biology, Greencastle, IN,
United States of America
| | - Pascal J. Lafontant
- DePauw University, Department of Biology, Greencastle, IN,
United States of America
| | - Nimesh Patel
- University of Houston, College of Optometry, Houston, TX,
United States of America
| | - Rolando E. Rumbaut
- Center for Translational Research on Inflammatory Diseases
(CTRID), Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX, United
States of America,Baylor College of Medicine, Children’s Nutrition
Center, Houston, TX, United States of America
| | - Alan R. Burns
- University of Houston, College of Optometry, Houston, TX,
United States of America,Baylor College of Medicine, Children’s Nutrition
Center, Houston, TX, United States of America
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30
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Targeted volumetric single-molecule localization microscopy of defined presynaptic structures in brain sections. Commun Biol 2021; 4:407. [PMID: 33767432 PMCID: PMC7994795 DOI: 10.1038/s42003-021-01939-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 03/03/2021] [Indexed: 11/17/2022] Open
Abstract
Revealing the molecular organization of anatomically precisely defined brain regions is necessary for refined understanding of synaptic plasticity. Although three-dimensional (3D) single-molecule localization microscopy can provide the required resolution, imaging more than a few micrometers deep into tissue remains challenging. To quantify presynaptic active zones (AZ) of entire, large, conditional detonator hippocampal mossy fiber (MF) boutons with diameters as large as 10 µm, we developed a method for targeted volumetric direct stochastic optical reconstruction microscopy (dSTORM). An optimized protocol for fast repeated axial scanning and efficient sequential labeling of the AZ scaffold Bassoon and membrane bound GFP with Alexa Fluor 647 enabled 3D-dSTORM imaging of 25 µm thick mouse brain sections and assignment of AZs to specific neuronal substructures. Quantitative data analysis revealed large differences in Bassoon cluster size and density for distinct hippocampal regions with largest clusters in MF boutons. Pauli et al. develop targeted volumetric dSTORM in order to image large hippocampal mossy fiber boutons (MFBs) in brain slices. They can identify synaptic targets of individual MFBs and measured size and density of Bassoon clusters within individual untruncated MFBs at nanoscopic resolution.
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31
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Peripheral nerve injury and sensitization underlie pain associated with oral cancer perineural invasion. Pain 2021; 161:2592-2602. [PMID: 32658150 DOI: 10.1097/j.pain.0000000000001986] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Cancer invading into nerves, termed perineural invasion (PNI), is associated with pain. Here, we show that oral cancer patients with PNI report greater spontaneous pain and mechanical allodynia compared with patients without PNI, suggesting that unique mechanisms drive PNI-induced pain. We studied the impact of PNI on peripheral nerve physiology and anatomy using a murine sciatic nerve PNI model. Mice with PNI exhibited spontaneous nociception and mechanical allodynia. Perineural invasion induced afterdischarge in A high-threshold mechanoreceptors (HTMRs), mechanical sensitization (ie, decreased mechanical thresholds) in both A and C HTMRs, and mechanical desensitization in low-threshold mechanoreceptors. Perineural invasion resulted in nerve damage, including axon loss, myelin damage, and axon degeneration. Electrophysiological evidence of nerve injury included decreased conduction velocity, and increased percentage of both mechanically insensitive and electrically unexcitable neurons. We conclude that PNI-induced pain is driven by nerve injury and peripheral sensitization in HTMRs.
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32
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Marzan DE, Brügger-Verdon V, West BL, Liddelow S, Samanta J, Salzer JL. Activated microglia drive demyelination via CSF1R signaling. Glia 2021; 69:1583-1604. [PMID: 33620118 DOI: 10.1002/glia.23980] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/04/2021] [Accepted: 02/05/2021] [Indexed: 02/06/2023]
Abstract
Microgliosis is a prominent pathological feature in many neurological diseases including multiple sclerosis (MS), a progressive auto-immune demyelinating disorder. The precise role of microglia, parenchymal central nervous system (CNS) macrophages, during demyelination, and the relative contributions of peripheral macrophages are incompletely understood. Classical markers used to identify microglia do not reliably discriminate between microglia and peripheral macrophages, confounding analyses. Here, we use a genetic fate mapping strategy to identify microglia as predominant responders and key effectors of demyelination in the cuprizone (CUP) model. Colony-stimulating factor 1 (CSF1), also known as macrophage colony-stimulating factor (M-CSF) - a secreted cytokine that regulates microglia development and survival-is upregulated in demyelinated white matter lesions. Depletion of microglia with the CSF1R inhibitor PLX3397 greatly abrogates the demyelination, loss of oligodendrocytes, and reactive astrocytosis that results from CUP treatment. Electron microscopy (EM) and serial block face imaging show myelin sheaths remain intact in CUP treated mice depleted of microglia. However, these CUP-damaged myelin sheaths are lost and robustly phagocytosed upon-repopulation of microglia. Direct injection of CSF1 into CNS white matter induces focal microgliosis and demyelination indicating active CSF1 signaling can promote demyelination. Finally, mice defective in adopting a toxic astrocyte phenotype that is driven by microglia nevertheless demyelinate normally upon CUP treatment implicating microglia rather than astrocytes as the primary drivers of CUP-mediated demyelination. Together, these studies indicate activated microglia are required for and can drive demyelination directly and implicate CSF1 signaling in these events.
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Affiliation(s)
- Dave E Marzan
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU Grossman School of Medicine, New York, New York, USA.,Translational Neuroscience Program, University of Pennsylvania, Philadelphia, PA, USA
| | - Valérie Brügger-Verdon
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU Grossman School of Medicine, New York, New York, USA
| | | | - Shane Liddelow
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU Grossman School of Medicine, New York, New York, USA
| | - Jayshree Samanta
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin, USA
| | - James L Salzer
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU Grossman School of Medicine, New York, New York, USA
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33
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Buss EW, Corbett NJ, Roberts JG, Ybarra N, Musial TF, Simkin D, Molina-Campos E, Oh KJ, Nielsen LL, Ayala GD, Mullen SA, Farooqi AK, D'Souza GX, Hill CL, Bean LA, Rogalsky AE, Russo ML, Curlik DM, Antion MD, Weiss C, Chetkovich DM, Oh MM, Disterhoft JF, Nicholson DA. Cognitive aging is associated with redistribution of synaptic weights in the hippocampus. Proc Natl Acad Sci U S A 2021; 118:e1921481118. [PMID: 33593893 PMCID: PMC7923642 DOI: 10.1073/pnas.1921481118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Behaviors that rely on the hippocampus are particularly susceptible to chronological aging, with many aged animals (including humans) maintaining cognition at a young adult-like level, but many others the same age showing marked impairments. It is unclear whether the ability to maintain cognition over time is attributable to brain maintenance, sufficient cognitive reserve, compensatory changes in network function, or some combination thereof. While network dysfunction within the hippocampal circuit of aged, learning-impaired animals is well-documented, its neurobiological substrates remain elusive. Here we show that the synaptic architecture of hippocampal regions CA1 and CA3 is maintained in a young adult-like state in aged rats that performed comparably to their young adult counterparts in both trace eyeblink conditioning and Morris water maze learning. In contrast, among learning-impaired, but equally aged rats, we found that a redistribution of synaptic weights amplifies the influence of autoassociational connections among CA3 pyramidal neurons, yet reduces the synaptic input onto these same neurons from the dentate gyrus. Notably, synapses within hippocampal region CA1 showed no group differences regardless of cognitive ability. Taking the data together, we find the imbalanced synaptic weights within hippocampal CA3 provide a substrate that can explain the abnormal firing characteristics of both CA3 and CA1 pyramidal neurons in aged, learning-impaired rats. Furthermore, our work provides some clarity with regard to how some animals cognitively age successfully, while others' lifespans outlast their "mindspans."
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Affiliation(s)
- Eric W Buss
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Nicola J Corbett
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Joshua G Roberts
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Natividad Ybarra
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Timothy F Musial
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Dina Simkin
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | | | - Kwang-Jin Oh
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Lauren L Nielsen
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Gelique D Ayala
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Sheila A Mullen
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Anise K Farooqi
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Gary X D'Souza
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Corinne L Hill
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Linda A Bean
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Annalise E Rogalsky
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Matthew L Russo
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Dani M Curlik
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Marci D Antion
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Craig Weiss
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Dane M Chetkovich
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232
| | - M Matthew Oh
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - John F Disterhoft
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611;
| | - Daniel A Nicholson
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612;
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34
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Steinkellner T, Madany M, Haberl MG, Zell V, Li C, Hu J, Mackey M, Ramachandra R, Adams S, Ellisman MH, Hnasko TS, Boassa D. Genetic Probe for Visualizing Glutamatergic Synapses and Vesicles by 3D Electron Microscopy. ACS Chem Neurosci 2021; 12:626-639. [PMID: 33522227 PMCID: PMC7899175 DOI: 10.1021/acschemneuro.0c00643] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 01/19/2021] [Indexed: 01/21/2023] Open
Abstract
Communication between neurons relies on the release of diverse neurotransmitters, which represent a key-defining feature of a neuron's chemical and functional identity. Neurotransmitters are packaged into vesicles by specific vesicular transporters. However, tools for labeling and imaging synapses and synaptic vesicles based on their neurochemical identity remain limited. We developed a genetically encoded probe to identify glutamatergic synaptic vesicles at the levels of both light and electron microscopy (EM) by fusing the mini singlet oxygen generator (miniSOG) probe to an intralumenal loop of the vesicular glutamate transporter-2. We then used a 3D imaging method, serial block-face scanning EM, combined with a deep learning approach for automatic segmentation of labeled synaptic vesicles to assess the subcellular distribution of transporter-defined vesicles at nanometer scale. These tools represent a new resource for accessing the subcellular structure and molecular machinery of neurotransmission and for transmitter-defined tracing of neuronal connectivity.
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Affiliation(s)
- Thomas Steinkellner
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Institute of Pharmacology, Center for Physiology and
Pharmacology, Medical University of Vienna, Vienna 1090,
Austria
| | - Matthew Madany
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
| | - Matthias G. Haberl
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
- Charité−Universitätsmedizin
Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität
zu Berlin, and Berlin Institute of Health, Neuroscience Research Center,
Berlin 10117, Germany
| | - Vivien Zell
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
| | - Carolina Li
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
| | - Junru Hu
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
| | - Mason Mackey
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
| | - Ranjan Ramachandra
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
| | - Stephen Adams
- Department of Pharmacology, University of
California, San Diego, La Jolla California 92093, United
States
| | - Mark H. Ellisman
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
| | - Thomas S. Hnasko
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Research Service, VA San Diego Healthcare
System, San Diego, California 92161, United
States
| | - Daniela Boassa
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
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35
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Pérez-Hernández M, Leo-Macias A, Keegan S, Jouni M, Kim JC, Agullo-Pascual E, Vermij S, Zhang M, Liang FX, Burridge P, Fenyö D, Rothenberg E, Delmar M. Structural and Functional Characterization of a Na v1.5-Mitochondrial Couplon. Circ Res 2021; 128:419-432. [PMID: 33342222 PMCID: PMC7864872 DOI: 10.1161/circresaha.120.318239] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
RATIONALE The cardiac sodium channel NaV1.5 has a fundamental role in excitability and conduction. Previous studies have shown that sodium channels cluster together in specific cellular subdomains. Their association with intracellular organelles in defined regions of the myocytes, and the functional consequences of that association, remain to be defined. OBJECTIVE To characterize a subcellular domain formed by sodium channel clusters in the crest region of the myocytes and the subjacent subsarcolemmal mitochondria. METHODS AND RESULTS Through a combination of imaging approaches including super-resolution microscopy and electron microscopy we identified, in adult cardiac myocytes, a NaV1.5 subpopulation in close proximity to subjacent subsarcolemmal mitochondria; we further found that subjacent subsarcolemmal mitochondria preferentially host the mitochondrial NCLX (Na+/Ca2+ exchanger). This anatomic proximity led us to investigate functional changes in mitochondria resulting from sodium channel activity. Upon TTX (tetrodotoxin) exposure, mitochondria near NaV1.5 channels accumulated more Ca2+ and showed increased reactive oxygen species production when compared with interfibrillar mitochondria. Finally, crosstalk between NaV1.5 channels and mitochondria was analyzed at a transcriptional level. We found that SCN5A (encoding NaV1.5) and SLC8B1 (which encode NaV1.5 and NCLX, respectively) are negatively correlated both in a human transcriptome data set (Genotype-Tissue Expression) and in human-induced pluripotent stem cell-derived cardiac myocytes deficient in SCN5A. CONCLUSIONS We describe an anatomic hub (a couplon) formed by sodium channel clusters and subjacent subsarcolemmal mitochondria. Preferential localization of NCLX to this domain allows for functional coupling where the extrusion of Ca2+ from the mitochondria is powered, at least in part, by the entry of sodium through NaV1.5 channels. These results provide a novel entry-point into a mechanistic understanding of the intersection between electrical and structural functions of the heart.
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Affiliation(s)
| | - Alejandra Leo-Macias
- Leon H Charney Division of Cardiology NYU Grossman School of Medicine. New York, NY
| | - Sarah Keegan
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology. NYU Grossman School of Medicine. New York, NY
| | - Mariam Jouni
- Department of Pharmacology, Northwestern University Feinberg School of Medicine. Chicago, IL
| | - Joon-Chul Kim
- Leon H Charney Division of Cardiology NYU Grossman School of Medicine. New York, NY
| | | | - Sarah Vermij
- Leon H Charney Division of Cardiology NYU Grossman School of Medicine. New York, NY
| | - Mingliang Zhang
- Leon H Charney Division of Cardiology NYU Grossman School of Medicine. New York, NY
| | - Feng-Xia Liang
- Microscopy laboratory, Division of Advanced Research Technologies. NYU Grossman School of Medicine. New York, NY
| | - Paul Burridge
- Department of Pharmacology, Northwestern University Feinberg School of Medicine. Chicago, IL
| | - David Fenyö
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology. NYU Grossman School of Medicine. New York, NY
| | - Eli Rothenberg
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology. NYU Grossman School of Medicine. New York, NY
| | - Mario Delmar
- Leon H Charney Division of Cardiology NYU Grossman School of Medicine. New York, NY
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36
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Merlini M, Rafalski VA, Ma K, Kim KY, Bushong EA, Rios Coronado PE, Yan Z, Mendiola AS, Sozmen EG, Ryu JK, Haberl MG, Madany M, Sampson DN, Petersen MA, Bardehle S, Tognatta R, Dean T, Acevedo RM, Cabriga B, Thomas R, Coughlin SR, Ellisman MH, Palop JJ, Akassoglou K. Microglial G i-dependent dynamics regulate brain network hyperexcitability. Nat Neurosci 2020; 24:19-23. [PMID: 33318667 PMCID: PMC8118167 DOI: 10.1038/s41593-020-00756-7] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 11/11/2020] [Indexed: 12/19/2022]
Abstract
Microglial surveillance is a key feature of brain physiology and disease. We found that Gi-dependent microglial dynamics prevent neuronal network hyperexcitability. By generating MgPTX mice to genetically inhibit Gi in microglia, we showed that sustained reduction of microglia brain surveillance and directed process motility induced spontaneous seizures and increased hypersynchrony upon physiologically evoked neuronal activity in awake adult mice. Thus, Gi-dependent microglia dynamics may prevent hyperexcitability in neurological diseases.
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Affiliation(s)
| | | | - Keran Ma
- Gladstone Institutes, San Francisco, CA, USA
| | - Keun-Young Kim
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA.,National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Eric A Bushong
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA.,National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | | | - Zhaoqi Yan
- Gladstone Institutes, San Francisco, CA, USA
| | | | - Elif G Sozmen
- Gladstone Institutes, San Francisco, CA, USA.,Department of Neurology and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | - Jae Kyu Ryu
- Gladstone Institutes, San Francisco, CA, USA.,Department of Neurology and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | - Matthias G Haberl
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA.,National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Matthew Madany
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA.,National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Daniel Naranjo Sampson
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA.,National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Mark A Petersen
- Gladstone Institutes, San Francisco, CA, USA.,Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | | | | | - Terry Dean
- Gladstone Institutes, San Francisco, CA, USA.,Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | | | | | | | - Shaun R Coughlin
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Mark H Ellisman
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA.,National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Jorge J Palop
- Gladstone Institutes, San Francisco, CA, USA.,Department of Neurology and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | - Katerina Akassoglou
- Gladstone Institutes, San Francisco, CA, USA. .,Department of Neurology and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA.
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37
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Synapse type-specific proteomic dissection identifies IgSF8 as a hippocampal CA3 microcircuit organizer. Nat Commun 2020; 11:5171. [PMID: 33057002 PMCID: PMC7560607 DOI: 10.1038/s41467-020-18956-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 09/23/2020] [Indexed: 12/20/2022] Open
Abstract
Excitatory and inhibitory neurons are connected into microcircuits that generate circuit output. Central in the hippocampal CA3 microcircuit is the mossy fiber (MF) synapse, which provides powerful direct excitatory input and indirect feedforward inhibition to CA3 pyramidal neurons. Here, we dissect its cell-surface protein (CSP) composition to discover novel regulators of MF synaptic connectivity. Proteomic profiling of isolated MF synaptosomes uncovers a rich CSP composition, including many CSPs without synaptic function and several that are uncharacterized. Cell-surface interactome screening identifies IgSF8 as a neuronal receptor enriched in the MF pathway. Presynaptic Igsf8 deletion impairs MF synaptic architecture and robustly decreases the density of bouton filopodia that provide feedforward inhibition. Consequently, IgSF8 loss impairs excitation/inhibition balance and increases excitability of CA3 pyramidal neurons. Our results provide insight into the CSP landscape and interactome of a specific excitatory synapse and reveal IgSF8 as a critical regulator of CA3 microcircuit connectivity and function. Mossy fiber synapses are key in CA3 microcircuit function. Here, the authors profile the mossy fiber synapse proteome and cell-surface interactome. They uncover a diverse repertoire of cell-surface proteins and identify the receptor IgSF8 as a regulator of CA3 microcircuit connectivity and function.
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38
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Yakoubi R, Rollenhagen A, von Lehe M, Shao Y, Sätzler K, Lübke JHR. Quantitative Three-Dimensional Reconstructions of Excitatory Synaptic Boutons in Layer 5 of the Adult Human Temporal Lobe Neocortex: A Fine-Scale Electron Microscopic Analysis. Cereb Cortex 2020; 29:2797-2814. [PMID: 29931200 DOI: 10.1093/cercor/bhy146] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 05/22/2018] [Accepted: 05/29/2018] [Indexed: 11/14/2022] Open
Abstract
Studies of synapses are available for different brain regions of several animal species including non-human primates, but comparatively little is known about their quantitative morphology in humans. Here, synaptic boutons in Layer 5 (L5) of the human temporal lobe (TL) neocortex were investigated in biopsy tissue, using fine-scale electron microscopy, and quantitative three-dimensional reconstructions. The size and organization of the presynaptic active zones (PreAZs), postsynaptic densities (PSDs), and that of the 3 distinct pools of synaptic vesicles (SVs) were particularly analyzed. L5 synaptic boutons were medium-sized (~6 μm2) with a single but relatively large PreAZ (~0.3 μm2). They contained a total of ~1500 SVs/bouton, ~20 constituting the putative readily releasable pool (RRP), ~180 the recycling pool (RP), and the remainder, the resting pool. The PreAZs, PSDs, and vesicle pools are ~3-fold larger than those of CNS synapses in other species. Astrocytic processes reached the synaptic cleft and may regulate the glutamate concentration. Profound differences exist between synapses in human TL neocortex and those described in various species, particularly in the size and geometry of PreAZs and PSDs, the large RRP/RP, and the astrocytic ensheathment suggesting high synaptic efficacy, strength, and modulation of synaptic transmission at human synapses.
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Affiliation(s)
- Rachida Yakoubi
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Leo-Brandt Str., Jülich, Germany
| | - Astrid Rollenhagen
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Leo-Brandt Str., Jülich, Germany
| | - Marec von Lehe
- University Hospital/Knappschaftskrankenhaus Bochum, In der Schornau 23-25, Bochum, Germany.,Department of Neurosurgery, Ruppiner Kliniken, Medizinische Hochschule Brandenburg, Fehrbelliner Str. 38, Neuruppin, Germany
| | - Yachao Shao
- Simulation Lab Neuroscience, Research Centre Jülich GmbH, Leo-Brandt Str., Jülich, Germany.,College of Computer, National University of Defense Technology, Changsha, China
| | - Kurt Sätzler
- School of Biomedical Sciences, University of Ulster, Cromore Rd., BT52 1SA, Londonderry, UK
| | - Joachim H R Lübke
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Leo-Brandt Str., Jülich, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, Medical Faculty/RWTH University Hospital Aachen, Pauwelsstr. 30, Aachen, Germany.,JARA Translational Brain Medicine, Germany
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39
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Andoh M, Shibata K, Okamoto K, Onodera J, Morishita K, Miura Y, Ikegaya Y, Koyama R. Exercise Reverses Behavioral and Synaptic Abnormalities after Maternal Inflammation. Cell Rep 2020; 27:2817-2825.e5. [PMID: 31167129 DOI: 10.1016/j.celrep.2019.05.015] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 03/11/2019] [Accepted: 05/01/2019] [Indexed: 12/17/2022] Open
Abstract
Abnormal behaviors in individuals with neurodevelopmental disorders are generally believed to be irreversible. Here, we show that voluntary wheel running ameliorates the abnormalities in sociability, repetitiveness, and anxiety observed in a mouse model of a neurodevelopmental disorder induced by maternal immune activation (MIA). Exercise activates a portion of dentate granule cells, normalizing the density of hippocampal CA3 synapses, which is excessive in the MIA-affected offspring. The synaptic surplus in the MIA offspring is induced by deficits in synapse engulfment by microglia, which is normalized by exercise through microglial activation. Finally, chemogenetically induced activation of granule cells promotes the engulfment of CA3 synapses. Thus, our study proposes a role of voluntary exercise in the modulation of behavioral and synaptic abnormalities in neurodevelopmental disorders.
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Affiliation(s)
- Megumi Andoh
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kazuki Shibata
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kazuki Okamoto
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Junya Onodera
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kohei Morishita
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yuki Miura
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Center for Information and Neural Networks, 1-4 Yamadaoka, Suita City, Osaka 565-0871, Japan
| | - Ryuta Koyama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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40
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Shiotani H, Miyata M, Kameyama T, Mandai K, Yamasaki M, Watanabe M, Mizutani K, Takai Y. Nectin‐2α is localized at cholinergic neuron dendrites and regulates synapse formation in the medial habenula. J Comp Neurol 2020; 529:450-477. [DOI: 10.1002/cne.24958] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 05/08/2020] [Accepted: 05/14/2020] [Indexed: 11/09/2022]
Affiliation(s)
- Hajime Shiotani
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology Kobe University Graduate School of Medicine Kobe Japan
| | - Muneaki Miyata
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology Kobe University Graduate School of Medicine Kobe Japan
| | - Takeshi Kameyama
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology Kobe University Graduate School of Medicine Kobe Japan
| | - Kenji Mandai
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology Kobe University Graduate School of Medicine Kobe Japan
- Department of Molecular and Cellular Neurobiology Kitasato University Graduate School of Medical Sciences Sagamihara Japan
- Department of Biochemistry Kitasato University School of Medicine Sagamihara Japan
| | - Miwako Yamasaki
- Department of Anatomy, Faculty of Medicine Hokkaido University Sapporo Japan
| | - Masahiko Watanabe
- Department of Anatomy, Faculty of Medicine Hokkaido University Sapporo Japan
| | - Kiyohito Mizutani
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology Kobe University Graduate School of Medicine Kobe Japan
| | - Yoshimi Takai
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology Kobe University Graduate School of Medicine Kobe Japan
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41
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Kim E, Lee J, Noh S, Kwon O, Mun JY. Double staining method for array tomography using scanning electron microscopy. Appl Microsc 2020; 50:14. [PMID: 33580409 PMCID: PMC7818292 DOI: 10.1186/s42649-020-00033-8] [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: 04/02/2020] [Accepted: 06/05/2020] [Indexed: 11/16/2022] Open
Abstract
Scanning electron microscopy (SEM) plays a central role in analyzing structures by imaging a large area of brain tissue at nanometer scales. A vast amount of data in the large area are required to study structural changes of cellular organelles in a specific cell, such as neurons, astrocytes, oligodendrocytes, and microglia among brain tissue, at sufficient resolution. Array tomography is a useful method for large-area imaging, and the osmium-thiocarbohydrazide-osmium (OTO) and ferrocyanide-reduced osmium methods are commonly used to enhance membrane contrast. Because many samples prepared using the conventional technique without en bloc staining are considered inadequate for array tomography, we suggested an alternative technique using post-staining conventional samples and compared the advantages.
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Affiliation(s)
- Eunjin Kim
- National Instrumentation Center for Environmental Management, Seoul National University, Seoul, South Korea
| | - Jiyoung Lee
- National Instrumentation Center for Environmental Management, Seoul National University, Seoul, South Korea
| | - Seulgi Noh
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu, South Korea.,Neural circuit research group, Korea Brain Research Institute, Daegu, South Korea
| | - Ohkyung Kwon
- National Instrumentation Center for Environmental Management, Seoul National University, Seoul, South Korea.
| | - Ji Young Mun
- Neural circuit research group, Korea Brain Research Institute, Daegu, South Korea.
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42
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Peterzan MA, Clarke WT, Lygate CA, Lake HA, Lau JYC, Miller JJ, Johnson E, Rayner JJ, Hundertmark MJ, Sayeed R, Petrou M, Krasopoulos G, Srivastava V, Neubauer S, Rodgers CT, Rider OJ. Cardiac Energetics in Patients With Aortic Stenosis and Preserved Versus Reduced Ejection Fraction. Circulation 2020; 141:1971-1985. [PMID: 32438845 PMCID: PMC7294745 DOI: 10.1161/circulationaha.119.043450] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Supplemental Digital Content is available in the text. Why some but not all patients with severe aortic stenosis (SevAS) develop otherwise unexplained reduced systolic function is unclear. We investigate the hypothesis that reduced creatine kinase (CK) capacity and flux is associated with this transition.
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Affiliation(s)
- Mark A Peterzan
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine (M.A.P., J.Y.C.L., J.J.M., J.J.R., M.J.H., S.N., O.J.R.), University of Oxford, United Kingdom
| | - William T Clarke
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences (W.T.C.), University of Oxford, United Kingdom
| | | | - Hannah A Lake
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine (H.A.L.), University of Oxford, United Kingdom
| | - Justin Y C Lau
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine (M.A.P., J.Y.C.L., J.J.M., J.J.R., M.J.H., S.N., O.J.R.), University of Oxford, United Kingdom
| | - Jack J Miller
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine (M.A.P., J.Y.C.L., J.J.M., J.J.R., M.J.H., S.N., O.J.R.), University of Oxford, United Kingdom
| | - Errin Johnson
- Dunn School of Pathology (E.J.), University of Oxford, United Kingdom
| | - Jennifer J Rayner
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine (M.A.P., J.Y.C.L., J.J.M., J.J.R., M.J.H., S.N., O.J.R.), University of Oxford, United Kingdom
| | - Moritz J Hundertmark
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine (M.A.P., J.Y.C.L., J.J.M., J.J.R., M.J.H., S.N., O.J.R.), University of Oxford, United Kingdom
| | - Rana Sayeed
- Department of Cardiothoracic Surgery, Oxford Heart Centre, John Radcliffe Hospital, United Kingdom (R.S., G.K., V.S.)
| | - Mario Petrou
- Department of Cardiothoracic Surgery, Royal Brompton and Harefield National Health Service Foundation Trust, London, United Kingdom (M.P.)
| | - George Krasopoulos
- Department of Cardiothoracic Surgery, Oxford Heart Centre, John Radcliffe Hospital, United Kingdom (R.S., G.K., V.S.)
| | - Vivek Srivastava
- Department of Cardiothoracic Surgery, Oxford Heart Centre, John Radcliffe Hospital, United Kingdom (R.S., G.K., V.S.)
| | - Stefan Neubauer
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine (M.A.P., J.Y.C.L., J.J.M., J.J.R., M.J.H., S.N., O.J.R.), University of Oxford, United Kingdom
| | | | - Oliver J Rider
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine (M.A.P., J.Y.C.L., J.J.M., J.J.R., M.J.H., S.N., O.J.R.), University of Oxford, United Kingdom
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43
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Murray KD, Liu XB, King AN, Luu JD, Cheng HJ. Age-Related Changes in Synaptic Plasticity Associated with Mossy Fiber Terminal Integration during Adult Neurogenesis. eNeuro 2020; 7:ENEURO.0030-20.2020. [PMID: 32332082 PMCID: PMC7240290 DOI: 10.1523/eneuro.0030-20.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/27/2020] [Accepted: 04/12/2020] [Indexed: 12/17/2022] Open
Abstract
Mouse hippocampus retains the capacity for neurogenesis throughout lifetime, but such plasticity decreases with age. Adult hippocampal neurogenesis (AHN) involves the birth, maturation, and synaptic integration of newborn granule cells (GCs) into preexisting hippocampal circuitry. While functional integration onto adult-born GCs has been extensively studied, maturation of efferent projections onto CA3 pyramidal cells is less understood, particularly in aged brain. Here, using combined light and reconstructive electron microscopy (EM), we describe the maturation of mossy fiber bouton (MFB) connectivity with CA3 pyramidal cells in young adult and aged mouse brain. We found mature synaptic contacts of newborn GCs were formed in both young and aged brains. However, the dynamics of their spatiotemporal development and the cellular process by which these cells functionally integrated over time were different. In young brain newborn GCs either formed independent nascent MFB synaptic contacts or replaced preexisting MFBs, but these contacts were pruned over time to a mature state. In aged brain only replacement of preexisting MFBs was observed and new contacts were without evidence of pruning. These data illustrate that functional synaptic integration of AHN occurs in young adult and aged brain, but with distinct dynamics. They suggest elimination of preexisting connectivity is required for the integration of adult-born GCs in aged brain.
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Affiliation(s)
- Karl D Murray
- Center for Neuroscience
- Department of Psychiatry and Behavioral Neuroscience
| | | | | | | | - Hwai-Jong Cheng
- Center for Neuroscience
- Department of Neurobiology, Physiology and behavior
- Department of Pathology and Laboratory Medicine, University of California, Davis, Davis, CA 95618
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44
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FAITG JULIE, DAVEY TRACEY, TURNBULL DOUGM, WHITE KATHRYN, VINCENT AMYE. Mitochondrial morphology and function: two for the price of one! J Microsc 2020; 278:89-106. [DOI: 10.1111/jmi.12891] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 03/26/2020] [Accepted: 03/27/2020] [Indexed: 11/28/2022]
Affiliation(s)
- JULIE FAITG
- Wellcome Centre for Mitochondrial Research, Translational and Clinical ResearchNewcastle University Newcastle UK
- Electron Microscopy Research ServicesNewcastle University Newcastle UK
| | - TRACEY DAVEY
- Electron Microscopy Research ServicesNewcastle University Newcastle UK
| | - DOUG M. TURNBULL
- Wellcome Centre for Mitochondrial Research, Translational and Clinical ResearchNewcastle University Newcastle UK
| | - KATHRYN WHITE
- Electron Microscopy Research ServicesNewcastle University Newcastle UK
| | - AMY E. VINCENT
- Wellcome Centre for Mitochondrial Research, Translational and Clinical ResearchNewcastle University Newcastle UK
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45
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Sanculi D, Pannoni KE, Bushong EA, Crump M, Sung M, Popat V, Zaher C, Hicks E, Song A, Mofakham N, Li P, Antzoulatos EG, Fioravante D, Ellisman MH, DeBello WM. Toric Spines at a Site of Learning. eNeuro 2020; 7:ENEURO.0197-19.2019. [PMID: 31822521 PMCID: PMC6944481 DOI: 10.1523/eneuro.0197-19.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 10/23/2019] [Accepted: 11/02/2019] [Indexed: 11/21/2022] Open
Abstract
We discovered a new type of dendritic spine. It is found on space-specific neurons in the barn owl inferior colliculus, a site of experience-dependent plasticity. Connectomic analysis revealed dendritic protrusions of unusual morphology including topological holes, hence termed "toric" spines (n = 76). More significantly, presynaptic terminals converging onto individual toric spines displayed numerous active zones (up to 49) derived from multiple axons (up to 11) with incoming trajectories distributed widely throughout 3D space. This arrangement is suited to integrate input sources. Dense reconstruction of two toric spines revealed that they were unconnected with the majority (∼84%) of intertwined axons, implying a high capacity for information storage. We developed an ex vivo slice preparation and provide the first published data on space-specific neuron intrinsic properties, including cellular subtypes with and without toric-like spines. We propose that toric spines are a cellular locus of sensory integration and behavioral learning.
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Affiliation(s)
- Daniel Sanculi
- Center for Neuroscience, University of California, Davis, CA 95618
| | | | - Eric A Bushong
- National Center for Molecular Imaging Research, University of California, La Jolla, CA 92093
| | - Michael Crump
- Center for Neuroscience, University of California, Davis, CA 95618
| | - Michelle Sung
- Center for Neuroscience, University of California, Davis, CA 95618
| | - Vyoma Popat
- Center for Neuroscience, University of California, Davis, CA 95618
| | - Camilia Zaher
- Center for Neuroscience, University of California, Davis, CA 95618
| | - Emma Hicks
- Center for Neuroscience, University of California, Davis, CA 95618
| | - Ashley Song
- Center for Neuroscience, University of California, Davis, CA 95618
| | - Nikan Mofakham
- Center for Neuroscience, University of California, Davis, CA 95618
| | - Peining Li
- Center for Neuroscience, University of California, Davis, CA 95618
| | | | | | - Mark H Ellisman
- National Center for Molecular Imaging Research, University of California, La Jolla, CA 92093
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46
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Rodriguez-Moreno J, Rollenhagen A, Arlandis J, Santuy A, Merchan-Pérez A, DeFelipe J, Lübke JHR, Clasca F. Quantitative 3D Ultrastructure of Thalamocortical Synapses from the "Lemniscal" Ventral Posteromedial Nucleus in Mouse Barrel Cortex. Cereb Cortex 2019; 28:3159-3175. [PMID: 28968773 PMCID: PMC6946031 DOI: 10.1093/cercor/bhx187] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 07/03/2017] [Indexed: 01/20/2023] Open
Abstract
Thalamocortical synapses from “lemniscal” neurons of the dorsomedial portion of the rodent ventral posteromedial nucleus (VPMdm) are able to induce with remarkable efficacy, despite their relative low numbers, the firing of primary somatosensory cortex (S1) layer 4 (L4) neurons. To which extent this high efficacy depends on structural synaptic features remains unclear. Using both serial transmission (TEM) and focused ion beam milling scanning electron microscopy (FIB/SEM), we 3D-reconstructed and quantitatively analyzed anterogradely labeled VPMdm axons in L4 of adult mouse S1. All VPMdm synapses are asymmetric. Virtually all are established by axonal boutons, 53% of which contact multiple (2–4) elements (overall synapse/bouton ratio = 1.6). Most boutons are large (mean 0.47 μm3), and contain 1–3 mitochondria. Vesicle pools and postsynaptic density (PSD) surface areas are large compared to others in rodent cortex. Most PSDs are complex. Most synapses (83%) are established on dendritic spine heads. Furthermore, 15% of the postsynaptic spines receive a second, symmetric synapse. In addition, 13% of the spine heads have a large protrusion inserted into a membrane pouch of the VPMdm bouton. The unusual combination of structural features in VPMdm synapses is likely to contribute significantly to the high efficacy, strength, and plasticity of these thalamocortical synapses.
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Affiliation(s)
- Javier Rodriguez-Moreno
- Department of Anatomy & Neuroscience, School of Medicine, Autonoma de Madrid University, Madrid, Spain
| | - Astrid Rollenhagen
- Institute of Neuroscience and Medicine INM-2, Research Centre Jülich GmbH, Jülich, Germany
| | - Jaime Arlandis
- Department of Anatomy & Neuroscience, School of Medicine, Autonoma de Madrid University, Madrid, Spain
| | - Andrea Santuy
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain.,CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Madrid, Spain
| | - Angel Merchan-Pérez
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain.,CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Madrid, Spain.,Departamento de Arquitectura y Tecnología de Sistemas Informáticos, Universidad Politécnica de Madrid, Boadilla del Monte, Madrid, Spain
| | - Javier DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain.,CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Madrid, Spain.,Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Joachim H R Lübke
- Institute of Neuroscience and Medicine INM-2, Research Centre Jülich GmbH, Jülich, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, Aachen, Germany.,JARA-Brain Medicine, Aachen, Germany
| | - Francisco Clasca
- Department of Anatomy & Neuroscience, School of Medicine, Autonoma de Madrid University, Madrid, Spain
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Karabağ C, Jones ML, Peddie CJ, Weston AE, Collinson LM, Reyes-Aldasoro CC. Segmentation and Modelling of the Nuclear Envelope of HeLa Cells Imaged with Serial Block Face Scanning Electron Microscopy. J Imaging 2019; 5:75. [PMID: 34460669 PMCID: PMC8320948 DOI: 10.3390/jimaging5090075] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 09/06/2019] [Accepted: 09/10/2019] [Indexed: 12/11/2022] Open
Abstract
This paper describes an unsupervised algorithm, which segments the nuclear envelope of HeLa cells imaged by Serial Block Face Scanning Electron Microscopy. The algorithm exploits the variations of pixel intensity in different cellular regions by calculating edges, which are then used to generate superpixels. The superpixels are morphologically processed and those that correspond to the nuclear region are selected through the analysis of size, position, and correspondence with regions detected in neighbouring slices. The nuclear envelope is segmented from the nuclear region. The three-dimensional segmented nuclear envelope is then modelled against a spheroid to create a two-dimensional (2D) surface. The 2D surface summarises the complex 3D shape of the nuclear envelope and allows the extraction of metrics that may be relevant to characterise the nature of cells. The algorithm was developed and validated on a single cell and tested in six separate cells, each with 300 slices of 2000 × 2000 pixels. Ground truth was available for two of these cells, i.e., 600 hand-segmented slices. The accuracy of the algorithm was evaluated with two similarity metrics: Jaccard Similarity Index and Mean Hausdorff distance. Jaccard values of the first/second segmentation were 93%/90% for the whole cell, and 98%/94% between slices 75 and 225, as the central slices of the nucleus are more regular than those on the extremes. Mean Hausdorff distances were 9/17 pixels for the whole cells and 4/13 pixels for central slices. One slice was processed in approximately 8 s and a whole cell in 40 min. The algorithm outperformed active contours in both accuracy and time.
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Affiliation(s)
- Cefa Karabağ
- Department of Electrical and Electronic Engineering, Research Centre for Biomedical Engineering, School of Mathematics, Computer Science and Engineering, City, University of London, London EC1V 0HB, UK
| | - Martin L. Jones
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK; (M.L.J.); (C.J.P.); (A.E.W.); (L.M.C.)
| | - Christopher J. Peddie
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK; (M.L.J.); (C.J.P.); (A.E.W.); (L.M.C.)
| | - Anne E. Weston
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK; (M.L.J.); (C.J.P.); (A.E.W.); (L.M.C.)
| | - Lucy M. Collinson
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK; (M.L.J.); (C.J.P.); (A.E.W.); (L.M.C.)
| | - Constantino Carlos Reyes-Aldasoro
- Department of Electrical and Electronic Engineering, Research Centre for Biomedical Engineering, School of Mathematics, Computer Science and Engineering, City, University of London, London EC1V 0HB, UK
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48
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Trinchero MF, Herrero M, Monzón-Salinas MC, Schinder AF. Experience-Dependent Structural Plasticity of Adult-Born Neurons in the Aging Hippocampus. Front Neurosci 2019; 13:739. [PMID: 31379489 PMCID: PMC6651579 DOI: 10.3389/fnins.2019.00739] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 07/02/2019] [Indexed: 12/28/2022] Open
Abstract
Synaptic modification in cortical structures underlies the acquisition of novel information that results in learning and memory formation. In the adult dentate gyrus, circuit remodeling is boosted by the generation of new granule cells (GCs) that contribute to specific aspects of memory encoding. These forms of plasticity decrease in the aging brain, where both the rate of adult neurogenesis and the speed of morphological maturation of newly generated neurons decline. In the young-adult brain, a brief novel experience accelerates the integration of new neurons. The extent to which such degree of plasticity is preserved in the aging hippocampus remains unclear. In this work, we characterized the time course of functional integration of adult-born GCs in middle-aged mice. We performed whole-cell recordings in developing GCs from Ascl1CreERT2;CAGfloxStopTom mice and found a late onset of functional excitatory synaptogenesis, which occurred at 4 weeks (vs. 2 weeks in young-adult mice). Overall mature excitability and maximal glutamatergic connectivity were achieved at 10 weeks. In contrast, large mossy fiber boutons (MFBs) in CA3 displayed mature morphological features including filopodial extensions at 4 weeks, suggesting that efferent connectivity develops faster than afference. Notably, new GCs from middle-aged mice exposed to enriched environment for 7 days showed an advanced degree of maturity at 3 weeks, revealed by the high frequency of excitatory postsynaptic responses, complex dendritic trees, and large size of MFBs with filopodial extensions. These findings demonstrate that adult-born neurons act as sensors that transduce behavioral stimuli into major network remodeling in the aging brain.
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Affiliation(s)
| | | | | | - Alejandro F. Schinder
- Laboratorio de Plasticidad Neuronal, Fundación Instituto Leloir, Buenos Aires, Argentina
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49
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Sleep Deprivation by Exposure to Novel Objects Increases Synapse Density and Axon-Spine Interface in the Hippocampal CA1 Region of Adolescent Mice. J Neurosci 2019; 39:6613-6625. [PMID: 31263066 DOI: 10.1523/jneurosci.0380-19.2019] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/24/2019] [Accepted: 06/10/2019] [Indexed: 11/21/2022] Open
Abstract
Sleep has been hypothesized to rebalance overall synaptic strength after ongoing learning during waking leads to net synaptic potentiation. If so, because synaptic strength and size are correlated, synapses on average should be larger after wake and smaller after sleep. This prediction was recently confirmed in mouse cerebral cortex using serial block-face electron microscopy (SBEM). However, whether these findings extend to other brain regions is unknown. Moreover, sleep deprivation by gentle handling was reported to produce hippocampal spine loss, raising the question of whether synapse size and number are differentially affected by sleep and waking. Here we applied SBEM to measure axon-spine interface (ASI), the contact area between pre-synapse and post-synapse, and synapse density in CA1 stratum radiatum. Adolescent YFP-H mice were studied after 6-8 h of sleep (S = 6), spontaneous wake at night (W = 4) or wake enforced during the day by novelty exposure (EW = 4; males/females balanced). In each animal ≥425 ASIs were measured and synaptic vesicles were counted in ~100 synapses/mouse. Reconstructed dendrites included many small, nonperforated synapses and fewer large, perforated synapses. Relative to S, ASI sizes in perforated synapses shifted toward higher values after W and more so after EW. ASI sizes in nonperforated synapses grew after EW relative to S and W, and so did their density. ASI size correlated with presynaptic vesicle number but the proportion of readily available vesicles decreased after EW, suggesting presynaptic fatigue. Thus, CA1 synapses undergo changes consistent with sleep-dependent synaptic renormalization and their number increases after extended wake.SIGNIFICANCE STATEMENT Sleep benefits learning, memory consolidation, and the integration of new with old memories, but the underlying mechanisms remain highly debated. One hypothesis suggests that sleep's cognitive benefits stem from its ability to renormalize total synaptic strength, after ongoing learning during wake leads to net synaptic potentiation. Supporting evidence for this hypothesis mainly comes from the cerebral cortex, including the observation that cortical synapses are larger after wake and smaller after sleep. Using serial electron microscopy, we find here that sleep/wake synaptic changes consistent with sleep-dependent synaptic renormalization also occur in the CA1 region. Thus, the role of sleep in maintaining synaptic homeostasis may extend to the hippocampus, a key area for learning and synaptic plasticity.
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50
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Das SC, Chen D, Callor WB, Christensen E, Coon H, Williams ME. DiI-mediated analysis of presynaptic and postsynaptic structures in human postmortem brain tissue. J Comp Neurol 2019; 527:3087-3098. [PMID: 31152449 DOI: 10.1002/cne.24722] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 05/24/2019] [Accepted: 05/24/2019] [Indexed: 12/20/2022]
Abstract
Most cognitive and psychiatric disorders are thought to be disorders of the synapse, yet the precise synapse defects remain unknown. Because synapses are highly specialized anatomical structures, defects in synapse formation and function can often be observed as changes in microscale neuroanatomy. Unfortunately, few methods are available for accurate analysis of synaptic structures in human postmortem tissues. Here, we present a methodological pipeline for assessing presynaptic and postsynaptic structures in human postmortem tissue that is accurate, rapid, and relatively inexpensive. Our method uses small tissue blocks from postmortem human brains, immersion fixation, lipophilic dye (DiI) labeling, and confocal microscopy. As proof of principle, we analyzed presynaptic and postsynaptic structures from hippocampi of 13 individuals aged 4 months to 71 years. Our results indicate that postsynaptic CA1 dendritic spine shape and density do not change in adults, while presynaptic DG mossy fiber boutons undergo significant structural rearrangements with normal aging. This suggests that mossy fiber synapses, which play a major role in learning and memory, may remain dynamic throughout life. Importantly, we find that human CA1 spine densities observed using this method on tissue that is up to 28 h postmortem is comparable to prior studies using tissue with much shorter postmortem intervals. Thus, the ease of our protocol and suitability on tissue with longer postmortem intervals should facilitate higher-powered studies of human presynaptic and postsynaptic structures in healthy and diseased states.
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Affiliation(s)
- Sujan C Das
- Department of Psychiatry, University of Utah School of Medicine, Salt Lake City, Utah
| | - Danli Chen
- Department of Psychiatry, University of Utah School of Medicine, Salt Lake City, Utah
| | | | - Eric Christensen
- Utah State Office of Medical Examiner, Utah Department of Health, Salt Lake City, Utah
| | - Hilary Coon
- Department of Psychiatry, University of Utah School of Medicine, Salt Lake City, Utah
| | - Megan E Williams
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah
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