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Serrano ME, Kim E, Petrinovic MM, Turkheimer F, Cash D. Imaging Synaptic Density: The Next Holy Grail of Neuroscience? Front Neurosci 2022; 16:796129. [PMID: 35401097 PMCID: PMC8990757 DOI: 10.3389/fnins.2022.796129] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 02/15/2022] [Indexed: 12/19/2022] Open
Abstract
The brain is the central and most complex organ in the nervous system, comprising billions of neurons that constantly communicate through trillions of connections called synapses. Despite being formed mainly during prenatal and early postnatal development, synapses are continually refined and eliminated throughout life via complicated and hitherto incompletely understood mechanisms. Failure to correctly regulate the numbers and distribution of synapses has been associated with many neurological and psychiatric disorders, including autism, epilepsy, Alzheimer’s disease, and schizophrenia. Therefore, measurements of brain synaptic density, as well as early detection of synaptic dysfunction, are essential for understanding normal and abnormal brain development. To date, multiple synaptic density markers have been proposed and investigated in experimental models of brain disorders. The majority of the gold standard methodologies (e.g., electron microscopy or immunohistochemistry) visualize synapses or measure changes in pre- and postsynaptic proteins ex vivo. However, the invasive nature of these classic methodologies precludes their use in living organisms. The recent development of positron emission tomography (PET) tracers [such as (18F)UCB-H or (11C)UCB-J] that bind to a putative synaptic density marker, the synaptic vesicle 2A (SV2A) protein, is heralding a likely paradigm shift in detecting synaptic alterations in patients. Despite their limited specificity, novel, non-invasive magnetic resonance (MR)-based methods also show promise in inferring synaptic information by linking to glutamate neurotransmission. Although promising, all these methods entail various advantages and limitations that must be addressed before becoming part of routine clinical practice. In this review, we summarize and discuss current ex vivo and in vivo methods of quantifying synaptic density, including an evaluation of their reliability and experimental utility. We conclude with a critical assessment of challenges that need to be overcome before successfully employing synaptic density biomarkers as diagnostic and/or prognostic tools in the study of neurological and neuropsychiatric disorders.
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Affiliation(s)
- Maria Elisa Serrano
- Department of Neuroimaging, The BRAIN Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.,Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, Kings College London, London, United Kingdom
| | - Eugene Kim
- Department of Neuroimaging, The BRAIN Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.,Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, Kings College London, London, United Kingdom
| | - Marija M Petrinovic
- Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.,MRC Centre for Neurodevelopmental Disorders, King's College London, London, United Kingdom
| | - Federico Turkheimer
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, Kings College London, London, United Kingdom
| | - Diana Cash
- Department of Neuroimaging, The BRAIN Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.,Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, Kings College London, London, United Kingdom
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2
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Chater TE, Goda Y. The Shaping of AMPA Receptor Surface Distribution by Neuronal Activity. Front Synaptic Neurosci 2022; 14:833782. [PMID: 35387308 PMCID: PMC8979068 DOI: 10.3389/fnsyn.2022.833782] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Accepted: 02/25/2022] [Indexed: 12/29/2022] Open
Abstract
Neurotransmission is critically dependent on the number, position, and composition of receptor proteins on the postsynaptic neuron. Of these, α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs) are responsible for the majority of postsynaptic depolarization at excitatory mammalian synapses following glutamate release. AMPARs are continually trafficked to and from the cell surface, and once at the surface, AMPARs laterally diffuse in and out of synaptic domains. Moreover, the subcellular distribution of AMPARs is shaped by patterns of activity, as classically demonstrated by the synaptic insertion or removal of AMPARs following the induction of long-term potentiation (LTP) and long-term depression (LTD), respectively. Crucially, there are many subtleties in the regulation of AMPARs, and exactly how local and global synaptic activity drives the trafficking and retention of synaptic AMPARs of different subtypes continues to attract attention. Here we will review how activity can have differential effects on AMPAR distribution and trafficking along with its subunit composition and phosphorylation state, and we highlight some of the controversies and remaining questions. As the AMPAR field is extensive, to say the least, this review will focus primarily on cellular and molecular studies in the hippocampus. We apologise to authors whose work could not be cited directly owing to space limitations.
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3
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Yu H, Bai XC, Wang W. Characterization of the subunit composition and structure of adult human glycine receptors. Neuron 2021; 109:2707-2716.e6. [PMID: 34473954 DOI: 10.1016/j.neuron.2021.08.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 07/23/2021] [Accepted: 08/16/2021] [Indexed: 11/27/2022]
Abstract
The strychnine-sensitive pentameric glycine receptor (GlyR) mediates fast inhibitory neurotransmission in the mammalian nervous system. Only heteromeric GlyRs mediate synaptic transmission, as they contain the β subunit that permits clustering at the synapse through its interaction with scaffolding proteins. Here, we show that α2 and β subunits assemble with an unexpected 4:1 stoichiometry to produce GlyR with native electrophysiological properties. We determined structures in multiple functional states at 3.6-3.8 Å resolutions and show how 4:1 stoichiometry is consistent with the structural features of α2β GlyR. Furthermore, we show that one single β subunit in each GlyR gives rise to the characteristic electrophysiological properties of heteromeric GlyR, while more β subunits render GlyR non-conductive. A single β subunit ensures a univalent GlyR-scaffold linkage, which means the scaffold alone regulates the cluster properties.
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Affiliation(s)
- Hailong Yu
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Xiao-Chen Bai
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Weiwei Wang
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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4
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Carvalhais LG, Martinho VC, Ferreiro E, Pinheiro PS. Unraveling the Nanoscopic Organization and Function of Central Mammalian Presynapses With Super-Resolution Microscopy. Front Neurosci 2021; 14:578409. [PMID: 33584169 PMCID: PMC7874199 DOI: 10.3389/fnins.2020.578409] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 12/03/2020] [Indexed: 12/22/2022] Open
Abstract
The complex, nanoscopic scale of neuronal function, taking place at dendritic spines, axon terminals, and other minuscule structures, cannot be adequately resolved using standard, diffraction-limited imaging techniques. The last couple of decades saw a rapid evolution of imaging methods that overcome the diffraction limit imposed by Abbe's principle. These techniques, including structured illumination microscopy (SIM), stimulated emission depletion (STED), photo-activated localization microscopy (PALM), and stochastic optical reconstruction microscopy (STORM), among others, have revolutionized our understanding of synapse biology. By exploiting the stochastic nature of fluorophore light/dark states or non-linearities in the interaction of fluorophores with light, by using modified illumination strategies that limit the excitation area, these methods can achieve spatial resolutions down to just a few tens of nm or less. Here, we review how these advanced imaging techniques have contributed to unprecedented insight into the nanoscopic organization and function of mammalian neuronal presynapses, revealing new organizational principles or lending support to existing views, while raising many important new questions. We further discuss recent technical refinements and newly developed tools that will continue to expand our ability to delve deeper into how synaptic function is orchestrated at the nanoscopic level.
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Affiliation(s)
- Lia G Carvalhais
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Vera C Martinho
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Elisabete Ferreiro
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Paulo S Pinheiro
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
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5
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Ferrini F, Perez-Sanchez J, Ferland S, Lorenzo LE, Godin AG, Plasencia-Fernandez I, Cottet M, Castonguay A, Wang F, Salio C, Doyon N, Merighi A, De Koninck Y. Differential chloride homeostasis in the spinal dorsal horn locally shapes synaptic metaplasticity and modality-specific sensitization. Nat Commun 2020; 11:3935. [PMID: 32769979 PMCID: PMC7414850 DOI: 10.1038/s41467-020-17824-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 07/22/2020] [Indexed: 02/06/2023] Open
Abstract
GABAA/glycine-mediated neuronal inhibition critically depends on intracellular chloride (Cl-) concentration which is mainly regulated by the K+-Cl- co-transporter 2 (KCC2) in the adult central nervous system (CNS). KCC2 heterogeneity thus affects information processing across CNS areas. Here, we uncover a gradient in Cl- extrusion capacity across the superficial dorsal horn (SDH) of the spinal cord (laminae I-II: LI-LII), which remains concealed under low Cl- load. Under high Cl- load or heightened synaptic drive, lower Cl- extrusion is unveiled in LI, as expected from the gradient in KCC2 expression found across the SDH. Blocking TrkB receptors increases KCC2 in LI, pointing to differential constitutive TrkB activation across laminae. Higher Cl- lability in LI results in rapidly collapsing inhibition, and a form of activity-dependent synaptic plasticity expressed as a continuous facilitation of excitatory responses. The higher metaplasticity in LI as compared to LII differentially affects sensitization to thermal and mechanical input. Thus, inconspicuous heterogeneity of Cl- extrusion across laminae critically shapes plasticity for selective nociceptive modalities.
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Affiliation(s)
- Francesco Ferrini
- Department of Veterinary Sciences, University of Turin, Turin, Italy.
- CERVO Brain Research Centre, Québec, QC, Canada.
- Department of Psychiatry and Neuroscience, Université Laval, Québec, QC, Canada.
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada.
| | - Jimena Perez-Sanchez
- CERVO Brain Research Centre, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | - Samuel Ferland
- CERVO Brain Research Centre, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | | | - Antoine G Godin
- CERVO Brain Research Centre, Québec, QC, Canada
- Department of Psychiatry and Neuroscience, Université Laval, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | - Isabel Plasencia-Fernandez
- CERVO Brain Research Centre, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | | | | | - Feng Wang
- CERVO Brain Research Centre, Québec, QC, Canada
| | - Chiara Salio
- Department of Veterinary Sciences, University of Turin, Turin, Italy
| | - Nicolas Doyon
- CERVO Brain Research Centre, Québec, QC, Canada
- Department of Mathematics and Statistics, Université Laval, Québec, QC, Canada
| | - Adalberto Merighi
- Department of Veterinary Sciences, University of Turin, Turin, Italy
| | - Yves De Koninck
- CERVO Brain Research Centre, Québec, QC, Canada
- Department of Psychiatry and Neuroscience, Université Laval, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
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6
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Lorenzo LE, Godin AG, Ferrini F, Bachand K, Plasencia-Fernandez I, Labrecque S, Girard AA, Boudreau D, Kianicka I, Gagnon M, Doyon N, Ribeiro-da-Silva A, De Koninck Y. Enhancing neuronal chloride extrusion rescues α2/α3 GABA A-mediated analgesia in neuropathic pain. Nat Commun 2020; 11:869. [PMID: 32054836 PMCID: PMC7018745 DOI: 10.1038/s41467-019-14154-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 12/16/2019] [Indexed: 02/06/2023] Open
Abstract
Spinal disinhibition has been hypothesized to underlie pain hypersensitivity in neuropathic pain. Apparently contradictory mechanisms have been reported, raising questions on the best target to produce analgesia. Here, we show that nerve injury is associated with a reduction in the number of inhibitory synapses in the spinal dorsal horn. Paradoxically, this is accompanied by a BDNF-TrkB-mediated upregulation of synaptic GABAARs and by an α1-to-α2GABAAR subunit switch, providing a mechanistic rationale for the analgesic action of the α2,3GABAAR benzodiazepine-site ligand L838,417 after nerve injury. Yet, we demonstrate that impaired Cl- extrusion underlies the failure of L838,417 to induce analgesia at high doses due to a resulting collapse in Cl- gradient, dramatically limiting the benzodiazepine therapeutic window. In turn, enhancing KCC2 activity not only potentiated L838,417-induced analgesia, it rescued its analgesic potential at high doses, revealing a novel strategy for analgesia in pathological pain, by combined targeting of the appropriate GABAAR-subtypes and restoring Cl- homeostasis.
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Affiliation(s)
- Louis-Etienne Lorenzo
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada
| | - Antoine G Godin
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Department of Psychiatry & Neuroscience, Université Laval, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | - Francesco Ferrini
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Department of Psychiatry & Neuroscience, Université Laval, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
- Department of Veterinary Sciences, University of Turin, Turin, Italy
| | - Karine Bachand
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
| | - Isabel Plasencia-Fernandez
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | - Simon Labrecque
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
| | - Alexandre A Girard
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Ecole Polytechnique, IP Paris, Palaiseau, France
| | - Dominic Boudreau
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | - Irenej Kianicka
- Chlorion Pharma, Laval, Québec, QC, Canada
- Laurent Pharmaceuticals Inc., Montreal, QC, Canada
| | - Martin Gagnon
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Centre for Innovation, University of Otago, Dunedin, New Zealand
| | - Nicolas Doyon
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Finite Element Interdisciplinary Research Group (GIREF), Université Laval, Québec, QC, Canada
| | - Alfredo Ribeiro-da-Silva
- Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada
- Department of Anatomy & Cell Biology, McGill University, Montreal, QC, Canada
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada
| | - Yves De Koninck
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada.
- Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada.
- Department of Psychiatry & Neuroscience, Université Laval, Québec, QC, Canada.
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada.
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada.
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7
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Liang Y. Emerging Concepts and Functions of Autophagy as a Regulator of Synaptic Components and Plasticity. Cells 2019; 8:cells8010034. [PMID: 30634508 PMCID: PMC6357011 DOI: 10.3390/cells8010034] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 12/23/2018] [Accepted: 01/03/2019] [Indexed: 12/15/2022] Open
Abstract
Protein homeostasis (proteostasis) is crucial to the maintenance of neuronal integrity and function. As the contact sites between neurons, synapses rely heavily on precisely regulated protein-protein interactions to support synaptic transmission and plasticity processes. Autophagy is an effective degradative pathway that can digest cellular components and maintain cellular proteostasis. Perturbations of autophagy have been implicated in aging and neurodegeneration due to a failure to remove damaged proteins and defective organelles. Recent evidence has demonstrated that autophagosome formation is prominent at synaptic terminals and neuronal autophagy is regulated in a compartment-specific fashion. Moreover, synaptic components including synaptic proteins and vesicles, postsynaptic receptors and synaptic mitochondria are known to be degraded by autophagy, thereby contributing to the remodeling of synapses. Indeed, emerging studies indicate that modulation of autophagy may be required for different forms of synaptic plasticity and memory formation. In this review, I will discuss our current understanding of the important role of neuronal/synaptic autophagy in maintaining neuronal function by degrading synaptic components and try to propose a conceptual framework of how the degradation of synaptic components via autophagy might impact synaptic function and contribute to synaptic plasticity.
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Affiliation(s)
- YongTian Liang
- Neurogenetik, Institut für Biologie, Freie Universität Berlin, 14195 Berlin, Germany.
- NeuroCure, Cluster of Excellence, Charité Universitätsmedizin, 10117 Berlin, Germany.
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8
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Xie X, Cheng YS, Wen MH, Calindi A, Yang K, Chiu CW, Chen TY. Quantifying the Oligomeric States of Membrane Proteins in Cells through Super-Resolution Localizations. J Phys Chem B 2018; 122:10496-10504. [PMID: 30384609 DOI: 10.1021/acs.jpcb.8b10402] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Transitions between different oligomeric states of membrane proteins are essential for proper cellular functions. However, the quantification of their oligomeric states in cells is technically challenging. Here we developed a new method to quantify oligomeric state(s) of highly expressed membrane proteins using the probability density function of molecule density ( PDFMD) calculated from super-resolution localizations. We provided the theoretical model of PDFMD, discussed the effects of protein concentration, cell geometry, and photophysics of fluorescent proteins on PDFMD, and provided experimental criteria for proper quantification of oligomeric states. This method was further validated using simulated single-molecule fluorescent movies and applied to two membrane proteins, UhpT and SbmA in E. coli. The study shows that PDFMD is useful in quantifying oligomeric states of membrane proteins in cells that can help in understanding cellular tasks. Potential applications to proteins with higher oligomeric states under high concentration and limitations of our methodology were also discussed.
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Affiliation(s)
- Xihong Xie
- Department of Chemistry , University of Houston , Houston , Texas 77204 , United States
| | - Yu-Shan Cheng
- Department of Chemistry , University of Houston , Houston , Texas 77204 , United States
| | - Meng-Hsuan Wen
- Department of Chemistry , University of Houston , Houston , Texas 77204 , United States
| | - Aparna Calindi
- Department of Chemistry , University of Houston , Houston , Texas 77204 , United States
| | - Karen Yang
- Department of Chemistry , University of Houston , Houston , Texas 77204 , United States
| | - Chi-Wei Chiu
- Department of Chemistry , University of Houston , Houston , Texas 77204 , United States
| | - Tai-Yen Chen
- Department of Chemistry , University of Houston , Houston , Texas 77204 , United States
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9
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Groeneweg FL, Trattnig C, Kuhse J, Nawrotzki RA, Kirsch J. Gephyrin: a key regulatory protein of inhibitory synapses and beyond. Histochem Cell Biol 2018; 150:489-508. [DOI: 10.1007/s00418-018-1725-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/07/2018] [Indexed: 12/26/2022]
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10
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Mei-Ling Liu J, Fair SR, Kaya B, Zuniga JN, Mostafa HR, Alves MJ, Stephens JA, Jones M, Aslan MT, Czeisler C, Otero JJ. Development of a Novel FIJI-Based Method to Investigate Neuronal Circuitry in Neonatal Mice. Dev Neurobiol 2018; 78:1146-1167. [PMID: 30136762 DOI: 10.1002/dneu.22636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 07/04/2018] [Accepted: 07/30/2018] [Indexed: 12/21/2022]
Abstract
The emergence of systems neuroscience tools requires parallel generation of objective analytical workflows for experimental neuropathology. We developed an objective analytical workflow that we used to determine how specific autonomic neural lineages change during postnatal development. While a wealth of knowledge exists regarding postnatal alterations in respiratory neural function, how these neural circuits change and develop in the weeks following birth remains less clear. In this study, we developed our workflow by combining genetic mouse modeling and quantitative immunofluorescent confocal microscopy and used this to examine the postnatal development of neural circuits derived from the transcription factors NKX2.2 and OLIG3 into three medullary respiratory nuclei. Our automated FIJI-based image analysis workflow rapidly and objectively quantified synaptic puncta in user-defined anatomic regions. Using our objective workflow, we found that the density and estimated total number of Nkx2.2-derived afferents into the pre-Bötzinger Complex significantly decreased with postnatal age during the first three weeks of postnatal life. These data indicate that Nkx2.2-derived structures differentially influence pre-Bötzinger Complex respiratory oscillations at different stages of postnatal development.
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Affiliation(s)
- Jillian Mei-Ling Liu
- Department of Pathology, Division of Neuropathology, The Ohio State University College of Medicine, Columbus, Ohio
| | - Summer Rose Fair
- Department of Pathology, Division of Neuropathology, The Ohio State University College of Medicine, Columbus, Ohio
| | - Behiye Kaya
- Department of Pathology, Division of Neuropathology, The Ohio State University College of Medicine, Columbus, Ohio
| | - Jessica Nabile Zuniga
- Department of Pathology, Division of Neuropathology, The Ohio State University College of Medicine, Columbus, Ohio
| | - Hasnaa Rashad Mostafa
- Department of Pathology, Division of Neuropathology, The Ohio State University College of Medicine, Columbus, Ohio
| | - Michele Joana Alves
- Department of Pathology, Division of Neuropathology, The Ohio State University College of Medicine, Columbus, Ohio
| | - Julie A Stephens
- Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University College of Medicine, Columbus, Ohio
| | - Mikayla Jones
- Department of Pathology, Division of Neuropathology, The Ohio State University College of Medicine, Columbus, Ohio
| | - M Tahir Aslan
- Department of Pathology, Division of Neuropathology, The Ohio State University College of Medicine, Columbus, Ohio
| | - Catherine Czeisler
- Department of Pathology, Division of Neuropathology, The Ohio State University College of Medicine, Columbus, Ohio
| | - José Javier Otero
- Department of Pathology, Division of Neuropathology, The Ohio State University College of Medicine, Columbus, Ohio
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11
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Alpha subunit-dependent glycine receptor clustering and regulation of synaptic receptor numbers. Sci Rep 2017; 7:10899. [PMID: 28883437 PMCID: PMC5589798 DOI: 10.1038/s41598-017-11264-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 08/21/2017] [Indexed: 02/08/2023] Open
Abstract
Accumulation of glycine receptors at synapses requires the interaction between the beta subunit of the receptor and the scaffold protein gephyrin. Here, we questioned whether different alpha subunits could modulate the receptors' diffusion and propensity to cluster at spinal cord synapses. Using quantitative photoactivated localisation microscopy we found that alpha-1 and alpha-3 containing glycine receptors display the same α3:β2 stoichiometry and gephyrin binding. Despite these similarities, alpha-3 containing receptors are less mobile and cluster at higher density compared to alpha-1, with 1500 versus 1100 complexes µm-2, respectively. Furthermore, we identified a subunit-specific regulation of glycine receptor copy numbers at synapses: when challenged with interleukin 1β, the synaptic occupancy of alpha-1 but not alpha-3 receptors was reduced. This mechanism may play a role in the cell-type dependent regulation of glycinergic currents in response to interleukin 1β and highlights the capacity of the alpha subunits to affect receptor-gephyrin binding at synapses.
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12
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13
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Linden R. The Biological Function of the Prion Protein: A Cell Surface Scaffold of Signaling Modules. Front Mol Neurosci 2017; 10:77. [PMID: 28373833 PMCID: PMC5357658 DOI: 10.3389/fnmol.2017.00077] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 03/06/2017] [Indexed: 12/18/2022] Open
Abstract
The prion glycoprotein (PrPC) is mostly located at the cell surface, tethered to the plasma membrane through a glycosyl-phosphatydil inositol (GPI) anchor. Misfolding of PrPC is associated with the transmissible spongiform encephalopathies (TSEs), whereas its normal conformer serves as a receptor for oligomers of the β-amyloid peptide, which play a major role in the pathogenesis of Alzheimer’s Disease (AD). PrPC is highly expressed in both the nervous and immune systems, as well as in other organs, but its functions are controversial. Extensive experimental work disclosed multiple physiological roles of PrPC at the molecular, cellular and systemic levels, affecting the homeostasis of copper, neuroprotection, stem cell renewal and memory mechanisms, among others. Often each such process has been heralded as the bona fide function of PrPC, despite restricted attention paid to a selected phenotypic trait, associated with either modulation of gene expression or to the engagement of PrPC with a single ligand. In contrast, the GPI-anchored prion protein was shown to bind several extracellular and transmembrane ligands, which are required to endow that protein with the ability to play various roles in transmembrane signal transduction. In addition, differing sets of those ligands are available in cell type- and context-dependent scenarios. To account for such properties, we proposed that PrPC serves as a dynamic platform for the assembly of signaling modules at the cell surface, with widespread consequences for both physiology and behavior. The current review advances the hypothesis that the biological function of the prion protein is that of a cell surface scaffold protein, based on the striking similarities of its functional properties with those of scaffold proteins involved in the organization of intracellular signal transduction pathways. Those properties are: the ability to recruit spatially restricted sets of binding molecules involved in specific signaling; mediation of the crosstalk of signaling pathways; reciprocal allosteric regulation with binding partners; compartmentalized responses; dependence of signaling properties upon posttranslational modification; and stoichiometric requirements and/or oligomerization-dependent impact on signaling. The scaffold concept may contribute to novel approaches to the development of effective treatments to hitherto incurable neurodegenerative diseases, through informed modulation of prion protein-ligand interactions.
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Affiliation(s)
- Rafael Linden
- Laboratory of Neurogenesis, Institute of Biophysics, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
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