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Michanski S, Kapoor R, Steyer AM, Möbius W, Früholz I, Ackermann F, Gültas M, Garner CC, Hamra FK, Neef J, Strenzke N, Moser T, Wichmann C. Piccolino is required for ribbon architecture at cochlear inner hair cell synapses and for hearing. EMBO Rep 2023; 24:e56702. [PMID: 37477166 PMCID: PMC10481675 DOI: 10.15252/embr.202256702] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 06/30/2023] [Accepted: 07/06/2023] [Indexed: 07/22/2023] Open
Abstract
Cochlear inner hair cells (IHCs) form specialized ribbon synapses with spiral ganglion neurons that tirelessly transmit sound information at high rates over long time periods with extreme temporal precision. This functional specialization is essential for sound encoding and is attributed to a distinct molecular machinery with unique players or splice variants compared to conventional neuronal synapses. Among these is the active zone (AZ) scaffold protein piccolo/aczonin, which is represented by its short splice variant piccolino at cochlear and retinal ribbon synapses. While the function of piccolo at synapses of the central nervous system has been intensively investigated, the role of piccolino at IHC synapses remains unclear. In this study, we characterize the structure and function of IHC synapses in piccolo gene-trap mutant rats (Pclogt/gt ). We find a mild hearing deficit with elevated thresholds and reduced amplitudes of auditory brainstem responses. Ca2+ channel distribution and ribbon morphology are altered in apical IHCs, while their presynaptic function seems to be unchanged. We conclude that piccolino contributes to the AZ organization in IHCs and is essential for normal hearing.
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Affiliation(s)
- Susann Michanski
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Center for Biostructural Imaging of NeurodegenerationUniversity Medical Center GöttingenGöttingenGermany
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”GöttingenGermany
- Multiscale Bioimaging of Excitable Cells, Cluster of ExcellenceGöttingenGermany
| | - Rohan Kapoor
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Synaptic Nanophysiology GroupMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
- IMPRS Molecular Biology, Göttingen Graduate School for Neuroscience and Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Anna M Steyer
- Electron Microscopy Core Unit, Department of NeurogeneticsMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Wiebke Möbius
- Multiscale Bioimaging of Excitable Cells, Cluster of ExcellenceGöttingenGermany
- Electron Microscopy Core Unit, Department of NeurogeneticsMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Iris Früholz
- Developmental, Neural, and Behavioral Biology Master ProgramUniversity of GöttingenGöttingenGermany
| | | | - Mehmet Gültas
- Faculty of AgricultureSouth Westphalia University of Applied SciencesSoestGermany
| | - Craig C Garner
- German Center for Neurodegenerative DiseasesBerlinGermany
- NeuroCureCluster of ExcellenceCharité – UniversitätsmedizinBerlinGermany
| | - F Kent Hamra
- Department of Obstetrics and GynecologyUniversity of Texas Southwestern Medical CenterDallasTXUSA
| | - Jakob Neef
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”GöttingenGermany
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Synaptic Nanophysiology GroupMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Nicola Strenzke
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”GöttingenGermany
- Auditory Systems Physiology Group, Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
| | - Tobias Moser
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”GöttingenGermany
- Multiscale Bioimaging of Excitable Cells, Cluster of ExcellenceGöttingenGermany
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Synaptic Nanophysiology GroupMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Center for Biostructural Imaging of NeurodegenerationUniversity Medical Center GöttingenGöttingenGermany
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”GöttingenGermany
- Multiscale Bioimaging of Excitable Cells, Cluster of ExcellenceGöttingenGermany
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2
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Garner CC, Ackermann F. Synaptic logistics: The presynaptic scaffold protein Piccolo a nodal point tuning synaptic vesicle recycling, maintenance and integrity. Mol Cell Neurosci 2023; 124:103795. [PMID: 36436725 DOI: 10.1016/j.mcn.2022.103795] [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: 09/30/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022] Open
Abstract
Properly working synapses are one important guarantor for a functional and healthy brain. They are small, densely packed structures, where information is transmitted through the release of neurotransmitters from synaptic vesicles (SVs). The latter cycle within the presynaptic terminal as they first fuse with the plasma membrane to deliver their neurotransmitter, and afterwards become recycled and prepared for a new release event. The synapse is an autonomous structure functioning mostly independent of the neuronal soma. Dysfunction in synaptic processes associated with local insults or genetic abnormalities can directly compromise synapse function and integrity and subsequently lead to the onset of neurodegenerative diseases. Therefore, measures need to be in place counteracting these threats for instance through the continuous replacement of old and damaged SV proteins. Interestingly recent studies show that the presynaptic scaffolding protein Piccolo contributes to health, function and integrity of synapses, as it mediates the delivery of synaptic proteins from the trans-Golgi network (TGN) towards synapses, as well as the local recycling and turnover of SV proteins within synaptic terminals. It can fulfill these various tasks through its multi-domain structure and ability to interact with numerous binding partners. In addition, Piccolo has recently been linked with the early onset neurodegenerative disease Pontocerebellar Hypoplasia Type 3 (PCH3) further underlying its importance for neuronal health. In this review, we will focus on Piccolo's contributions to synapse function, health and integrity and make a connection how those may contribute to the disease pattern of PCH3.
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Affiliation(s)
- Craig C Garner
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany; NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Germany
| | - Frauke Ackermann
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.
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Kudryashova I. Presynaptic Plasticity Is Associated with Actin Polymerization. BIOCHEMISTRY (MOSCOW) 2023; 88:392-403. [PMID: 37076285 DOI: 10.1134/s0006297923030082] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
Modulation of presynaptic short-term plasticity induced by actin polymerization was studied in rat hippocampal slices using the paired-pulse paradigm. Schaffer collaterals were stimulated with paired pulses with a 70-ms interstimulus interval every 30 s before and during perfusion with jasplakinolide, an activator of actin polymerization. Jasplakinolide application resulted in the increase in the amplitudes of CA3-CA1 responses (potentiation) accompanied by a decrease in the paired-pulse facilitation, suggesting induction of presynaptic modifications. Jasplakinolide-induced potentiation depended on the initial paired-pulse rate. These data indicate that the jasplakinolide-mediated changes in actin polymerization increased the probability of neurotransmitter release. Less typical for CA3-CA1 synapses responses, such as a very low paired-pulse ratio (close to 1 or even lower) or even paired-pulse depression, were affected differently. Thus, jasplakinolide caused potentiation of the second, but not the first response to the paired stimulus, which increased the paired-pulse ratio from 0.8 to 1.0 on average, suggesting a negative impact of jasplakinolide on the mechanisms promoting paired-pulse depression. In general, actin polymerization facilitated potentiation, although the patterns of potentiation differed depending on the initial synapse characteristics. We conclude that in addition to the increase in the neurotransmitter release probability, jasplakinolide induced other actin polymerization-dependent mechanisms, including those involved in the paired-pulse depression.
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Affiliation(s)
- Irina Kudryashova
- Laboratory of Functional Biochemistry of the Nervous System, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, 119991, Russia.
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4
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Wu X, Qiu H, Zhang M. Interactions between Membraneless Condensates and Membranous Organelles at the Presynapse: A Phase Separation View of Synaptic Vesicle Cycle. J Mol Biol 2023; 435:167629. [PMID: 35595170 DOI: 10.1016/j.jmb.2022.167629] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/03/2022] [Accepted: 05/04/2022] [Indexed: 02/04/2023]
Abstract
Action potential-induced neurotransmitter release in presynaptic boutons involves coordinated actions of a large list of proteins that are associated directly or indirectly with membrane structures including synaptic vesicles and plasma membranes. These proteins are often highly abundant in different synaptic bouton sub-compartments, and they rarely act alone. Instead, these proteins interact with each other forming intricate and distinct molecular complexes. Many of these complexes form condensed clusters on membrane surfaces. This review summarizes findings in recent years showing that many of presynaptic protein complex assemblies are formed via phase separation. These protein condensates extensively interact with lipid membranes via distinct modes, forming various mesoscale structures by different mode of organizations between membraneless condensates and membranous organelles. We discuss that such mesoscale interactions could have deep implications on mobilization, exocytosis, and retrieval of synaptic vesicles.
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Affiliation(s)
- Xiandeng Wu
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Hua Qiu
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingjie Zhang
- Greater Bay Biomedical Innocenter, Shenzhen Bay Laboratory, Shenzhen 518036, China; School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
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5
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Birdsall V, Kirwan K, Zhu M, Imoto Y, Wilson SM, Watanabe S, Waites CL. Axonal transport of Hrs is activity dependent and facilitates synaptic vesicle protein degradation. Life Sci Alliance 2022; 5:5/10/e202000745. [PMID: 35636965 PMCID: PMC9152131 DOI: 10.26508/lsa.202000745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 11/29/2022] Open
Abstract
This study describes an activity-dependent mechanism for transporting ESCRT-0 protein Hrs to synaptic vesicle (SV) pools, facilitating SV protein degradation in response to increased neuronal firing. Turnover of synaptic vesicle (SV) proteins is vital for the maintenance of healthy and functional synapses. SV protein turnover is driven by neuronal activity in an endosomal sorting complex required for transport (ESCRT)-dependent manner. Here, we characterize a critical step in this process: axonal transport of ESCRT-0 component Hrs, necessary for sorting proteins into the ESCRT pathway and recruiting downstream ESCRT machinery to catalyze multivesicular body (MVB) formation. We find that neuronal activity stimulates the formation of presynaptic endosomes and MVBs, as well as the motility of Hrs+ vesicles in axons and their delivery to SV pools. Hrs+ vesicles co-transport ESCRT-0 component STAM1 and comprise a subset of Rab5+ vesicles, likely representing pro-degradative early endosomes. Furthermore, we identify kinesin motor protein KIF13A as essential for the activity-dependent transport of Hrs to SV pools and the degradation of SV membrane proteins. Together, these data demonstrate a novel activity- and KIF13A-dependent mechanism for mobilizing axonal transport of ESCRT machinery to facilitate the degradation of SV membrane proteins.
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Affiliation(s)
- Veronica Birdsall
- Neurobiology and Behavior PhD Program, Columbia University, New York, NY, USA
| | - Konner Kirwan
- Neurobiology and Behavior PhD Program, Columbia University, New York, NY, USA
| | - Mei Zhu
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Yuuta Imoto
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD, USA
| | - Scott M Wilson
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Shigeki Watanabe
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD, USA.,Solomon H Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA
| | - Clarissa L Waites
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA .,Department of Neuroscience, Columbia University, New York, NY, USA
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6
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Cozzolino F, Vezzoli E, Cheroni C, Besusso D, Conforti P, Valenza M, Iacobucci I, Monaco V, Birolini G, Bombaci M, Falqui A, Saftig P, Rossi RL, Monti M, Cattaneo E, Zuccato C. ADAM10 hyperactivation acts on piccolo to deplete synaptic vesicle stores in Huntington's disease. Hum Mol Genet 2021; 30:1175-1187. [PMID: 33601422 DOI: 10.1093/hmg/ddab047] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 01/30/2021] [Accepted: 02/01/2021] [Indexed: 12/13/2022] Open
Abstract
Synaptic dysfunction and cognitive decline in Huntington's disease (HD) involve hyperactive A disintegrin and metalloproteinase domain-containing protein 10 (ADAM10). To identify the molecular mechanisms through which ADAM10 is associated with synaptic dysfunction in HD, we performed an immunoaffinity purification-mass spectrometry (IP-MS) study of endogenous ADAM10 in the brains of wild-type and HD mice. We found that proteins implicated in synapse organization, synaptic plasticity, and vesicle and organelles trafficking interact with ADAM10, suggesting that it may act as hub protein at the excitatory synapse. Importantly, the ADAM10 interactome is enriched in presynaptic proteins and ADAM10 co-immunoprecipitates with piccolo (PCLO), a key player in the recycling and maintenance of synaptic vesicles. In contrast, reduced ADAM10/PCLO immunoprecipitation occurs in the HD brain, with decreased density of synaptic vesicles in the reserve and docked pools at the HD presynaptic terminal. Conditional heterozygous deletion of ADAM10 in the forebrain of HD mice reduces active ADAM10 to wild-type level and normalizes ADAM10/PCLO complex formation and synaptic vesicle density and distribution. The results indicate that presynaptic ADAM10 and PCLO are a relevant component of HD pathogenesis.
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Affiliation(s)
- Flora Cozzolino
- Department of Chemical Sciences, University of Naples "Federico II", Naples 80126, Italy
- CEINGE Advanced Biotechnologies, Naples 80131, Italy
| | - Elena Vezzoli
- Department of Biomedical Sciences for Health, University of Milan, Milan 20133, Italy
| | - Cristina Cheroni
- European Institute of Oncology, IRCCS, Milan 20141, Italy
- Department of Oncology and Hemato-Oncology, University of Milan, Milan 20122, Italy
| | - Dario Besusso
- Department of Biosciences, University of Milan, Milan 20133, Italy
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan 20122, Italy
| | - Paola Conforti
- Department of Biosciences, University of Milan, Milan 20133, Italy
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan 20122, Italy
| | - Marta Valenza
- Department of Biosciences, University of Milan, Milan 20133, Italy
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan 20122, Italy
| | - Ilaria Iacobucci
- Department of Chemical Sciences, University of Naples "Federico II", Naples 80126, Italy
- CEINGE Advanced Biotechnologies, Naples 80131, Italy
| | - Vittoria Monaco
- CEINGE Advanced Biotechnologies, Naples 80131, Italy
- Biostructures and Biosystems National Institute (INBB), Rome 00136, Italy
| | - Giulia Birolini
- Department of Biosciences, University of Milan, Milan 20133, Italy
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan 20122, Italy
| | - Mauro Bombaci
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan 20122, Italy
| | - Andrea Falqui
- Biological and Environmental Science and Engineering (BESE) Division, NABLA Lab, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
| | - Paul Saftig
- Institute of Biochemistry, Christian-Albrechts-University of Kiel, Kiel D-24098, Germany
| | - Riccardo L Rossi
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan 20122, Italy
| | - Maria Monti
- Department of Chemical Sciences, University of Naples "Federico II", Naples 80126, Italy
- CEINGE Advanced Biotechnologies, Naples 80131, Italy
| | - Elena Cattaneo
- Department of Biosciences, University of Milan, Milan 20133, Italy
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan 20122, Italy
| | - Chiara Zuccato
- Department of Biosciences, University of Milan, Milan 20133, Italy
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan 20122, Italy
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7
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Ivanova D, Imig C, Camacho M, Reinhold A, Guhathakurta D, Montenegro-Venegas C, Cousin MA, Gundelfinger ED, Rosenmund C, Cooper B, Fejtova A. CtBP1-Mediated Membrane Fission Contributes to Effective Recycling of Synaptic Vesicles. Cell Rep 2021; 30:2444-2459.e7. [PMID: 32075774 PMCID: PMC7034063 DOI: 10.1016/j.celrep.2020.01.079] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 12/12/2019] [Accepted: 01/22/2020] [Indexed: 01/08/2023] Open
Abstract
Compensatory endocytosis of released synaptic vesicles (SVs) relies on coordinated signaling at the lipid-protein interface. Here, we address the synaptic function of C-terminal binding protein 1 (CtBP1), a ubiquitous regulator of gene expression and membrane trafficking in cultured hippocampal neurons. In the absence of CtBP1, synapses form in greater density and show changes in SV distribution and size. The increased basal neurotransmission and enhanced synaptic depression could be attributed to a higher vesicular release probability and a smaller fraction of release-competent SVs, respectively. Rescue experiments with specifically targeted constructs indicate that, while synaptogenesis and release probability are controlled by nuclear CtBP1, the efficient recycling of SVs relies on its synaptic expression. The ability of presynaptic CtBP1 to facilitate compensatory endocytosis depends on its membrane-fission activity and the activation of the lipid-metabolizing enzyme PLD1. Thus, CtBP1 regulates SV recycling by promoting a permissive lipid environment for compensatory endocytosis.
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Affiliation(s)
- Daniela Ivanova
- RG Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany; Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany; Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Cordelia Imig
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, German
| | - Marcial Camacho
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Annika Reinhold
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Debarpan Guhathakurta
- Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | | | - Michael A Cousin
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, EH9 9XD Edinburgh, UK
| | - Eckart D Gundelfinger
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany; Center for Behavioral Brain Science and Medical Faculty, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Christian Rosenmund
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Benjamin Cooper
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, German
| | - Anna Fejtova
- RG Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany; Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany; Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
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8
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Aparicio GI, Formoso K, León A, Frasch AC, Scorticati C. Identification of Potential Interacting Proteins With the Extracellular Loops of the Neuronal Glycoprotein M6a by TMT/MS. Front Synaptic Neurosci 2020; 12:28. [PMID: 32848694 PMCID: PMC7396582 DOI: 10.3389/fnsyn.2020.00028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 06/15/2020] [Indexed: 12/21/2022] Open
Abstract
Nowadays, great efforts are made to gain insight into the molecular mechanisms that underlie structural neuronal plasticity. Moreover, the identification of signaling pathways involved in the development of psychiatric disorders aids the screening of possible therapeutic targets. Genetic variations or alterations in GPM6A expression are linked to neurological disorders such as schizophrenia, depression, and Alzheimer's disease. GPM6A encodes the neuronal surface glycoprotein M6a that promotes filopodia/spine, dendrite, and synapse formation by unknown mechanisms. A substantial body of evidence suggests that the extracellular loops of M6a command its function. However, the proteins that associate with them and that modulate neuronal plasticity have not been determined yet. To address this question, we generated a chimera protein that only contains the extracellular loops of M6a and performed a co-immunoprecipitation with rat hippocampus samples followed by TMT/MS. Here, we report 72 proteins, which are good candidates to interact with M6a's extracellular loops and modify its function. Gene ontology (GO) analysis showed that 63% of the potential M6a's interactor proteins belong to the category "synapse," at both sides of the synaptic cleft, "neuron projections" (51%) and "presynapse" (49%). In this sense, we showed that endogenous M6a interacts with piccolo, synaptic vesicle protein 2B, and synapsin 1 in mature cultured hippocampal neurons. Interestingly, about 28% of the proteins left were related to the "myelin sheath" annotation, suggesting that M6a could interact with proteins at the surface of oligodendrocytes. Indeed, we demonstrated the (cis and trans) interaction between M6a and proteolipid protein (PLP) in neuroblastoma N2a cells. Finally, the 72 proteins were subjected to disease-associated genes and variants screening by DisGeNET. Apart from the diseases that have already been associated with M6a, most of the proteins are also involved in "autistic disorder," "epilepsy," and "seizures" increasing the spectrum of disorders in which M6a could play a role. Data are available via ProteomeXchange with identifier PXD017347.
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Affiliation(s)
- Gabriela I Aparicio
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (IIBio-UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Argentina
| | - Karina Formoso
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (IIBio-UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Argentina.,Instituto de Investigaciones Biomédicas (BIOMED), Facultad de Ciencias Médicas, Pontificia Universidad Católica Argentina (UCA), CONICET, San Martín, Argentina
| | - Antonella León
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (IIBio-UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Argentina
| | - Alberto C Frasch
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (IIBio-UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Argentina.,Vicerrectorado, Edificio de Gobierno, Universidad Nacional de San Martín (UNSAM), San Martín, Argentina
| | - Camila Scorticati
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (IIBio-UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Argentina
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9
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Huang TT, Smith R, Bacos K, Song DY, Faull RM, Waldvogel HJ, Li JY. No symphony without bassoon and piccolo: changes in synaptic active zone proteins in Huntington's disease. Acta Neuropathol Commun 2020; 8:77. [PMID: 32493491 PMCID: PMC7268643 DOI: 10.1186/s40478-020-00949-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 05/19/2020] [Indexed: 11/10/2022] Open
Abstract
Prominent features of HD neuropathology are the intranuclear and cytoplasmic inclusions of huntingtin and striatal and cortical neuronal cell death. Recently, synaptic defects have been reported on HD-related studies, including impairment of neurotransmitter release and alterations of synaptic components. However, the definite characteristics of synapse dysfunction and the underlying mechanisms remain largely unknown. We studied the gene expression levels and patterns of a number of proteins forming the cytoskeletal matrix of the presynaptic active zones in HD transgenic mice (R6/1), in hippocampal neuronal cultures overexpressing mutant huntingtin and in postmortem brain tissues of HD patients. To investigate the interactions between huntingtin and active proteins, we performed confocal microscopic imaging and immunoprecipitation in mouse and HEK 293 cell line models. The mRNA and protein levels of Bassoon were reduced in mouse and cell culture models of HD and in brain tissues of patients with HD. Moreover, a striking re-distribution of a complex of proteins including Bassoon, Piccolo and Munc 13-1 from the cytoplasm and synapses into intranuclear huntingtin aggregates with loss of active zone proteins and dendritic spines. This re-localization was age-dependent and coincided with the formation of huntingtin aggregates. Using co-immunoprecipitation, we demonstrated that huntingtin interacts with Bassoon, and that this interaction is likely mediated by a third linking protein. Three structural proteins involved in neurotransmitter release in the presynaptic active zones of neurons are altered in expression and that the proteins are redistributed from their normal functional site into mutant huntingtin aggregates.
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10
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Serine-Arginine Protein Kinase SRPK2 Modulates the Assembly of the Active Zone Scaffolding Protein CAST1/ERC2. Cells 2019; 8:cells8111333. [PMID: 31671734 PMCID: PMC6912806 DOI: 10.3390/cells8111333] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/08/2019] [Accepted: 10/11/2019] [Indexed: 01/10/2023] Open
Abstract
Neurons release neurotransmitters at a specialized region of the presynaptic membrane, the active zone (AZ), where a complex meshwork of proteins organizes the release apparatus. The formation of this proteinaceous cytomatrix at the AZ (CAZ) depends on precise homo- and hetero-oligomerizations of distinct CAZ proteins. The CAZ protein CAST1/ERC2 contains four coiled-coil (CC) domains that interact with other CAZ proteins, but also promote self-assembly, which is an essential step for its integration during AZ formation. The self-assembly and synaptic recruitment of the Drosophila protein Bruchpilot (BRP), a partial homolog of CAST1/ERC2, is modulated by the serine-arginine protein kinase (SRPK79D). Here, we demonstrate that overexpression of the vertebrate SRPK2 regulates the self-assembly of CAST1/ERC2 in HEK293T, SH-SY5Y and HT-22 cells and the CC1 and CC4 domains are involved in this process. Moreover, the isoform SRPK2 forms a complex with CAST1/ERC2 when co-expressed in HEK293T and SH-SY5Y cells. More importantly, SRPK2 is present in brain synaptic fractions and synapses, suggesting that this protein kinase might control the level of self-aggregation of CAST1/ERC2 in synapses, and thereby modulate presynaptic assembly.
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11
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Lindhout FW, Cao Y, Kevenaar JT, Bodzęta A, Stucchi R, Boumpoutsari MM, Katrukha EA, Altelaar M, MacGillavry HD, Hoogenraad CC. VAP-SCRN1 interaction regulates dynamic endoplasmic reticulum remodeling and presynaptic function. EMBO J 2019; 38:e101345. [PMID: 31441084 PMCID: PMC6792018 DOI: 10.15252/embj.2018101345] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 07/11/2019] [Accepted: 07/17/2019] [Indexed: 01/08/2023] Open
Abstract
In neurons, the continuous and dynamic endoplasmic reticulum (ER) network extends throughout the axon, and its dysfunction causes various axonopathies. However, it remains largely unknown how ER integrity and remodeling modulate presynaptic function in mammalian neurons. Here, we demonstrated that ER membrane receptors VAPA and VAPB are involved in modulating the synaptic vesicle (SV) cycle. VAP interacts with secernin-1 (SCRN1) at the ER membrane via a single FFAT-like motif. Similar to VAP, loss of SCRN1 or SCRN1-VAP interactions resulted in impaired SV cycling. Consistently, SCRN1 or VAP depletion was accompanied by decreased action potential-evoked Ca2+ responses. Additionally, we found that VAP-SCRN1 interactions play an important role in maintaining ER continuity and dynamics, as well as presynaptic Ca2+ homeostasis. Based on these findings, we propose a model where the ER-localized VAP-SCRN1 interactions provide a novel control mechanism to tune ER remodeling and thereby modulate Ca2+ dynamics and SV cycling at presynaptic sites. These data provide new insights into the molecular mechanisms controlling ER structure and dynamics, and highlight the relevance of ER function for SV cycling.
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Affiliation(s)
- Feline W Lindhout
- Department of BiologyCell BiologyUtrecht UniversityUtrechtThe Netherlands
| | - Yujie Cao
- Department of BiologyCell BiologyUtrecht UniversityUtrechtThe Netherlands
| | - Josta T Kevenaar
- Department of BiologyCell BiologyUtrecht UniversityUtrechtThe Netherlands
| | - Anna Bodzęta
- Department of BiologyCell BiologyUtrecht UniversityUtrechtThe Netherlands
| | - Riccardo Stucchi
- Department of BiologyCell BiologyUtrecht UniversityUtrechtThe Netherlands
- Biomolecular Mass Spectrometry and ProteomicsBijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical SciencesUtrecht UniversityUtrechtThe Netherlands
| | | | - Eugene A Katrukha
- Department of BiologyCell BiologyUtrecht UniversityUtrechtThe Netherlands
| | - Maarten Altelaar
- Biomolecular Mass Spectrometry and ProteomicsBijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical SciencesUtrecht UniversityUtrechtThe Netherlands
| | | | - Casper C Hoogenraad
- Department of BiologyCell BiologyUtrecht UniversityUtrechtThe Netherlands
- Department of NeuroscienceGenentech, Inc.South San FranciscoCAUSA
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12
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Ackermann F, Schink KO, Bruns C, Izsvák Z, Hamra FK, Rosenmund C, Garner CC. Critical role for Piccolo in synaptic vesicle retrieval. eLife 2019; 8:46629. [PMID: 31074746 PMCID: PMC6541439 DOI: 10.7554/elife.46629] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 05/09/2019] [Indexed: 12/30/2022] Open
Abstract
Loss of function of the active zone protein Piccolo has recently been linked to a disease, Pontocerebellar Hypoplasia type 3, which causes brain atrophy. Here, we address how Piccolo inactivation in rat neurons adversely affects synaptic function and thus may contribute to neuronal loss. Our analysis shows that Piccolo is critical for the recycling and maintenance of synaptic vesicles. We find that boutons lacking Piccolo have deficits in the Rab5/EEA1 dependent formation of early endosomes and thus the recycling of SVs. Mechanistically, impaired Rab5 function was caused by reduced synaptic recruitment of Pra1, known to interact selectively with the zinc finger domains of Piccolo. Importantly, over-expression of GTPase deficient Rab5 or the Znf1 domain of Piccolo restores the size and recycling of SV pools. These data provide a molecular link between the active zone and endosome sorting at synapses providing hints to how Piccolo contributes to developmental and psychiatric disorders.
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Affiliation(s)
- Frauke Ackermann
- German Center for Neurodegenerative Diseases e.V. (DZNE), Charité Medical University, Berlin, Germany
| | - Kay Oliver Schink
- Center for Cancer Biomedicine, University of Oslo, Norwegian Radium Hospital, Oslo, Norway
| | - Christine Bruns
- German Center for Neurodegenerative Diseases e.V. (DZNE), Charité Medical University, Berlin, Germany
| | - Zsuzsanna Izsvák
- Max-Delbrück Center for Molecular Medicine in the Helmholtz Society, Berlin, Germany
| | - F Kent Hamra
- Department of Obstetrics and Gynecology, University of Texas Southwestern, Dallas, United States
| | - Christian Rosenmund
- NeuroCure Cluster of Excellence, Neuroscience Research Center, Charité Medical University, Berlin, Germany
| | - Craig Curtis Garner
- German Center for Neurodegenerative Diseases e.V. (DZNE), Charité Medical University, Berlin, Germany
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13
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Lee K, Vyas Y, Garner CC, Montgomery JM. Autism‐associated
Shank3
mutations alter mGluR expression and mGluR‐dependent but not NMDA receptor‐dependent long‐term depression. Synapse 2019; 73:e22097. [DOI: 10.1002/syn.22097] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 02/20/2019] [Accepted: 03/10/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Kevin Lee
- Department of Physiology, Centre for Brain Research University of Auckland Auckland New Zealand
| | - Yukti Vyas
- Department of Physiology, Centre for Brain Research University of Auckland Auckland New Zealand
| | - Craig C. Garner
- German Center for Neurodegenerative Disorders Charité – Universitätsmedizin Berlin Berlin Germany
| | - Johanna M. Montgomery
- Department of Physiology, Centre for Brain Research University of Auckland Auckland New Zealand
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14
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Zhang Q, Lee WCA, Paul DL, Ginty DD. Multiplexed peroxidase-based electron microscopy labeling enables simultaneous visualization of multiple cell types. Nat Neurosci 2019; 22:828-839. [PMID: 30886406 PMCID: PMC6555422 DOI: 10.1038/s41593-019-0358-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 02/07/2019] [Indexed: 01/06/2023]
Abstract
Electron microscopy (EM) is a powerful tool for circuit mapping, but identifying specific cell types in EM datasets remains a major challenge. Here we describe a technique enabling simultaneous visualization of multiple, genetically identified neuronal populations so that synaptic interactions between them can be unequivocally defined. We present 15 AAV constructs and six mouse reporter lines for multiplexed EM labeling in the mammalian nervous system. These reporters feature dAPEX2, which exhibits dramatically improved signal compared to previously described ascorbate peroxidases. By targeting this enhanced peroxidase to different subcellular compartments, multiple orthogonal reporters can be simultaneously visualized and distinguished under EM using a protocol compatible with existing EM pipelines. Proof-of-principle double and triple EM labeling experiments demonstrated synaptic connections between primary afferents, descending cortical inputs, and inhibitory interneurons in the spinal cord dorsal horn. Our multiplexed peroxidase-based EM labeling system should therefore greatly facilitate analysis of connectivity in the nervous system.
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Affiliation(s)
- Qiyu Zhang
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Wei-Chung A Lee
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA
| | - David L Paul
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.
| | - David D Ginty
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA. .,Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA.
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15
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Abstract
Live imaging of microfluidically isolated axons permits study of the dynamic behavior of fluorescently tagged proteins and vesicles in these neuronal processes. We use this technique to study the motility and transport of ESCRT proteins in axons of primary hippocampal neurons. This chapter details the preparation of microfluidic chambers, as well as the seeding, fluidic isolation, and lentiviral transduction of hippocampal neurons in these chambers, optimized for the study of ESCRT protein dynamics.
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16
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Ha HTT, Leal-Ortiz S, Lalwani K, Kiyonaka S, Hamachi I, Mysore SP, Montgomery JM, Garner CC, Huguenard JR, Kim SA. Shank and Zinc Mediate an AMPA Receptor Subunit Switch in Developing Neurons. Front Mol Neurosci 2018; 11:405. [PMID: 30524232 PMCID: PMC6256285 DOI: 10.3389/fnmol.2018.00405] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 10/15/2018] [Indexed: 11/18/2022] Open
Abstract
During development, pyramidal neurons undergo dynamic regulation of AMPA receptor (AMPAR) subunit composition and density to help drive synaptic plasticity and maturation. These normal developmental changes in AMPARs are particularly vulnerable to risk factors for Autism Spectrum Disorders (ASDs), which include loss or mutations of synaptic proteins and environmental insults, such as dietary zinc deficiency. Here, we show how Shank2 and Shank3 mediate a zinc-dependent regulation of AMPAR function and subunit switch from GluA2-lacking to GluA2-containing AMPARs. Over development, we found a concomitant increase in Shank2 and Shank3 with GluA2 at synapses, implicating these molecules as potential players in AMPAR maturation. Since Shank activation and function require zinc, we next studied whether neuronal activity regulated postsynaptic zinc at glutamatergic synapses. Zinc was found to increase transiently and reversibly with neuronal depolarization at synapses, which could affect Shank and AMPAR localization and activity. Elevated zinc induced multiple functional changes in AMPAR, indicative of a subunit switch. Specifically, zinc lengthened the decay time of AMPAR-mediated synaptic currents and reduced their inward rectification in young hippocampal neurons. Mechanistically, both Shank2 and Shank3 were necessary for the zinc-sensitive enhancement of AMPAR-mediated synaptic transmission and act in concert to promote removal of GluA1 while enhancing recruitment of GluA2 at pre-existing Shank puncta. These findings highlight a cooperative local dynamic regulation of AMPAR subunit switch controlled by zinc signaling through Shank2 and Shank3 to shape the biophysical properties of developing glutamatergic synapses. Given the zinc sensitivity of young neurons and its dependence on Shank2 and Shank3, genetic mutations and/or environmental insults during early development could impair synaptic maturation and circuit formation that underlie ASD etiology.
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Affiliation(s)
- Huong T T Ha
- Department of Neurology & Neurological Sciences, School of Medicine, Stanford University, Stanford, CA, United States.,Neurosciences Graduate Program, School of Medicine, Stanford University, Stanford, CA, United States
| | - Sergio Leal-Ortiz
- Department of Material Science & Engineering, School of Engineering, Stanford University, Stanford, CA, United States
| | - Kriti Lalwani
- Department of Neurology & Neurological Sciences, School of Medicine, Stanford University, Stanford, CA, United States
| | - Shigeki Kiyonaka
- Department of Synthetic Chemistry & Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Itaru Hamachi
- Department of Synthetic Chemistry & Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Shreesh P Mysore
- Department of Psychological & Brain Sciences, Johns Hopkins University, Baltimore, MD, United States
| | - Johanna M Montgomery
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Craig C Garner
- German Center for Neurodegenerative Diseases (DZNE), Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - John R Huguenard
- Department of Neurology & Neurological Sciences, School of Medicine, Stanford University, Stanford, CA, United States
| | - Sally A Kim
- Department of Neurology & Neurological Sciences, School of Medicine, Stanford University, Stanford, CA, United States
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17
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Lira M, Arancibia D, Orrego PR, Montenegro-Venegas C, Cruz Y, García J, Leal-Ortiz S, Godoy JA, Gundelfinger ED, Inestrosa NC, Garner CC, Zamorano P, Torres VI. The Exocyst Component Exo70 Modulates Dendrite Arbor Formation, Synapse Density, and Spine Maturation in Primary Hippocampal Neurons. Mol Neurobiol 2018; 56:4620-4638. [DOI: 10.1007/s12035-018-1378-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 10/01/2018] [Indexed: 02/07/2023]
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18
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Chen H, Shi L, Liu L, Yin S, Aiken S, Wang J. Noise-induced Cochlear Synaptopathy and Signal Processing Disorders. Neuroscience 2018; 407:41-52. [PMID: 30267832 DOI: 10.1016/j.neuroscience.2018.09.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 09/17/2018] [Accepted: 09/18/2018] [Indexed: 01/18/2023]
Abstract
Noise-induced hidden hearing loss (NIHHL) has attracted great attention in hearing research and clinical audiology since the discovery of significant noise-induced synaptic damage in the absence of permanent threshold shifts (PTS) in animal models. Although the extant evidence for this damage is based on animal models, NIHHL likely occurs in humans as well. This review focuses on three issues concerning NIHHL that are somewhat controversial: (1) whether disrupted synapses can be re-established; (2) whether synaptic damage and repair are responsible for the initial temporal threshold shifts (TTS) and subsequent recovery; and (3) the relationship between the synaptic damage and repair processes and neural coding deficits. We conclude that, after a single, brief noise exposure, (1) the damaged and the totally destroyed synapses can be partially repaired, but the repaired synapses are functionally abnormal; (2) While deficits are observed in some aspects of neural responses related to temporal and intensity coding in the auditory nerve, we did not find strong evidence for hypothesized coding-in-noise deficits; (3) the sensitivity and the usefulness of the envelope following responses to amplitude modulation signals in detecting cochlear synaptopathy is questionable.
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Affiliation(s)
- Hengchao Chen
- Otolaryngology Research Institute, 6th Affiliated Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Lijuan Shi
- Department of Physiology, Medical College of Southeast University, Nanjing, China
| | - Lijie Liu
- Department of Physiology, Medical College of Southeast University, Nanjing, China
| | - Shankai Yin
- Otolaryngology Research Institute, 6th Affiliated Hospital, Shanghai Jiao Tong University, Shanghai, China.
| | - Steven Aiken
- School of Communication Sciences and Disorders, Dalhousie University, Halfiax, Canada
| | - Jian Wang
- Otolaryngology Research Institute, 6th Affiliated Hospital, Shanghai Jiao Tong University, Shanghai, China; School of Communication Sciences and Disorders, Dalhousie University, Halfiax, Canada.
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19
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Nguyen TL, Duchon A, Manousopoulou A, Loaëc N, Villiers B, Pani G, Karatas M, Mechling AE, Harsan LA, Limanton E, Bazureau JP, Carreaux F, Garbis SD, Meijer L, Herault Y. Correction of cognitive deficits in mouse models of Down syndrome by a pharmacological inhibitor of DYRK1A. Dis Model Mech 2018; 11:dmm035634. [PMID: 30115750 PMCID: PMC6176987 DOI: 10.1242/dmm.035634] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 08/01/2018] [Indexed: 12/13/2022] Open
Abstract
Growing evidence supports the implication of DYRK1A in the development of cognitive deficits seen in Down syndrome (DS) and Alzheimer's disease (AD). We here demonstrate that pharmacological inhibition of brain DYRK1A is able to correct recognition memory deficits in three DS mouse models with increasing genetic complexity [Tg(Dyrk1a), Ts65Dn, Dp1Yey], all expressing an extra copy of Dyrk1a Overexpressed DYRK1A accumulates in the cytoplasm and at the synapse. Treatment of the three DS models with the pharmacological DYRK1A inhibitor leucettine L41 leads to normalization of DYRK1A activity and corrects the novel object cognitive impairment observed in these models. Brain functional magnetic resonance imaging reveals that this cognitive improvement is paralleled by functional connectivity remodelling of core brain areas involved in learning/memory processes. The impact of Dyrk1a trisomy and L41 treatment on brain phosphoproteins was investigated by a quantitative phosphoproteomics method, revealing the implication of synaptic (synapsin 1) and cytoskeletal components involved in synaptic response and axonal organization. These results encourage the development of DYRK1A inhibitors as drug candidates to treat cognitive deficits associated with DS and AD.
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Affiliation(s)
- Thu Lan Nguyen
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Department of Translational Medicine and Neurogenetics, 67400 Illkirch, France
- Centre National de la Recherche Scientifique, UMR7104, 67400 Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, U964, 67400 Illkirch, France
- Université de Strasbourg, 67400 Illkirch, France
- ManRos Therapeutics, Perharidy Research Center, 29680 Roscoff, Bretagne, France
| | - Arnaud Duchon
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Department of Translational Medicine and Neurogenetics, 67400 Illkirch, France
- Centre National de la Recherche Scientifique, UMR7104, 67400 Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, U964, 67400 Illkirch, France
- Université de Strasbourg, 67400 Illkirch, France
| | - Antigoni Manousopoulou
- Faculty of Medicine/Cancer Sciences & Clinical and Experimental Medicine, University of Southampton, Center for Proteomic Research, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Nadège Loaëc
- ManRos Therapeutics, Perharidy Research Center, 29680 Roscoff, Bretagne, France
| | - Benoît Villiers
- ManRos Therapeutics, Perharidy Research Center, 29680 Roscoff, Bretagne, France
| | - Guillaume Pani
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Department of Translational Medicine and Neurogenetics, 67400 Illkirch, France
- Centre National de la Recherche Scientifique, UMR7104, 67400 Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, U964, 67400 Illkirch, France
- Université de Strasbourg, 67400 Illkirch, France
| | - Meltem Karatas
- Laboratory of Engineering, Informatics and Imaging (ICube), Integrative multimodal imaging in healthcare (IMIS), UMR 7357, and University Hospital Strasbourg, Department of Biophysics and Nuclear Medicine, University of Strasbourg, 67400 Illkirch, France
- Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Breisacher Strasse 60a, 79106 Freiburg, Germany
| | - Anna E Mechling
- Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Breisacher Strasse 60a, 79106 Freiburg, Germany
| | - Laura-Adela Harsan
- Laboratory of Engineering, Informatics and Imaging (ICube), Integrative multimodal imaging in healthcare (IMIS), UMR 7357, and University Hospital Strasbourg, Department of Biophysics and Nuclear Medicine, University of Strasbourg, 67400 Illkirch, France
- Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Breisacher Strasse 60a, 79106 Freiburg, Germany
| | - Emmanuelle Limanton
- Université de Rennes 1, ISCR (Institut des sciences chimiques de Rennes)-UMR, 6226, 35000 Rennes, France
| | - Jean-Pierre Bazureau
- Université de Rennes 1, ISCR (Institut des sciences chimiques de Rennes)-UMR, 6226, 35000 Rennes, France
| | - François Carreaux
- Université de Rennes 1, ISCR (Institut des sciences chimiques de Rennes)-UMR, 6226, 35000 Rennes, France
| | - Spiros D Garbis
- Faculty of Medicine/Cancer Sciences & Clinical and Experimental Medicine, University of Southampton, Center for Proteomic Research, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Laurent Meijer
- ManRos Therapeutics, Perharidy Research Center, 29680 Roscoff, Bretagne, France
| | - Yann Herault
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Department of Translational Medicine and Neurogenetics, 67400 Illkirch, France
- Centre National de la Recherche Scientifique, UMR7104, 67400 Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, U964, 67400 Illkirch, France
- Université de Strasbourg, 67400 Illkirch, France
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20
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Zhu M, Cortese GP, Waites CL. Parkinson's disease-linked Parkin mutations impair glutamatergic signaling in hippocampal neurons. BMC Biol 2018; 16:100. [PMID: 30200940 PMCID: PMC6130078 DOI: 10.1186/s12915-018-0567-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 08/24/2018] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Parkinson's disease (PD)-associated E3 ubiquitin ligase Parkin is enriched at glutamatergic synapses, where it ubiquitinates multiple substrates, suggesting that its mutation/loss-of-function could contribute to the etiology of PD by disrupting excitatory neurotransmission. Here, we evaluate the impact of four common PD-associated Parkin point mutations (T240M, R275W, R334C, G430D) on glutamatergic synaptic function in hippocampal neurons. RESULTS We find that expression of these point mutants in cultured hippocampal neurons from Parkin-deficient and Parkin-null backgrounds alters NMDA and AMPA receptor-mediated currents and cell-surface levels and prevents the induction of long-term depression. Mechanistically, we demonstrate that Parkin regulates NMDA receptor trafficking through its ubiquitination of GluN1, and that all four mutants are impaired in this ubiquitinating activity. Furthermore, Parkin regulates synaptic AMPA receptor trafficking via its binding and retention of the postsynaptic scaffold Homer1, and all mutants are similarly impaired in this capacity. CONCLUSION Our findings demonstrate that pathogenic Parkin mutations disrupt glutamatergic synaptic transmission in hippocampal neurons by impeding NMDA and AMPA receptor trafficking. Such effects may contribute to the pathophysiology of PD in PARK2 patients.
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Affiliation(s)
- Mei Zhu
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032 USA
| | - Giuseppe P. Cortese
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032 USA
- Department of Psychiatry, Columbia University Medical Center, New York, NY USA
| | - Clarissa L. Waites
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032 USA
- Department of Neuroscience, Columbia University, New York, NY USA
- Waites Lab, 650 W. 168th St. Black Building 1210B, New York, NY 10032 USA
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21
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Falk N, Kessler K, Schramm SF, Boldt K, Becirovic E, Michalakis S, Regus-Leidig H, Noegel AA, Ueffing M, Thiel CT, Roepman R, Brandstätter JH, Gießl A. Functional analyses of Pericentrin and Syne-2 interaction in ciliogenesis. J Cell Sci 2018; 131:jcs.218487. [PMID: 30054381 DOI: 10.1242/jcs.218487] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 07/12/2018] [Indexed: 01/31/2023] Open
Abstract
Pericentrin (Pcnt) is a multifunctional scaffold protein and mutations in the human PCNT gene are associated with several diseases, including ciliopathies. Pcnt plays a crucial role in ciliary development in olfactory receptor neurons, but its function in the photoreceptor-connecting cilium is unknown. We downregulated Pcnt in the retina ex vivo and in vivo via a virus-based RNA interference approach to study Pcnt function in photoreceptors. ShRNA-mediated knockdown of Pcnt impaired the development of the connecting cilium and the outer segment of photoreceptors, and caused a nuclear migration defect. In protein interaction screens, we found that the outer nuclear membrane protein Syne-2 (also known as Nesprin-2) is an interaction partner of Pcnt in photoreceptors. Syne-2 is important for positioning murine photoreceptor cell nuclei and for centrosomal migration during early ciliogenesis. CRISPR/Cas9-mediated knockout of Syne-2 in cell culture led to an overexpression and mislocalization of Pcnt and to ciliogenesis defects. Our findings suggest that the Pcnt-Syne-2 complex is important for ciliogenesis and outer segment formation during retinal development and plays a role in nuclear migration.
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Affiliation(s)
- Nathalie Falk
- Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Kristin Kessler
- Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Sinja-Fee Schramm
- Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Karsten Boldt
- Division of Experimental Ophthalmology and Medical Proteome Center, Center of Ophthalmology, University of Tübingen, 72074 Tübingen, Germany
| | - Elvir Becirovic
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Stylianos Michalakis
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Hanna Regus-Leidig
- Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Angelika A Noegel
- Institute of Biochemistry I, Medical Faculty, University Hospital, University of Cologne, 50931 Cologne, Germany
| | - Marius Ueffing
- Division of Experimental Ophthalmology and Medical Proteome Center, Center of Ophthalmology, University of Tübingen, 72074 Tübingen, Germany
| | - Christian T Thiel
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Ronald Roepman
- Department of Human Genetics, Radboud University Medical Center, Nijmegen 6525 GA, The Netherlands
| | | | - Andreas Gießl
- Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
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22
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Chen X, Wang X, Yang Y, Li Z, Zhang Y, Gao W, Xiao J, Li B. Schwann cells protect against CaMKII- and PKA-dependent Acrylamide-induced Synapsin I phosphorylation. Brain Res 2018; 1701:18-27. [PMID: 30028969 DOI: 10.1016/j.brainres.2018.07.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 07/11/2018] [Accepted: 07/13/2018] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To explore the effects of Acrylamide (ACR), as well as the influence of Schwann cells (SCs), on the signal transduction pathway and phosphorylation of Synapsin I in a Human neuroblastoma cell line (NB-1). METHODS NB-1s, NB-1s co-cultured with SCs, and a negative control group (NB-1 cells without ACR) were exposed to gradient concentrations of ACR for 48 h. Cell proliferation and viability were determined by MTT. Protein and mRNA expression levels of typical kinases (i.e., cAMP-dependent protein kinase [PKA], calcium/calmodulin-dependent protein kinase II [CaMKII], and mitogen-activated protein kinase-extracellular signal-regulated kinases [MAPK-Erk]), their phosphorylation status, as well as Synapsin I and its phosphorylation status, were tested by western blotting and polymerase chain reaction, respectively. Further, the effect of SCs on ACR-induced NB-1 cell toxicity was evaluated. RESULTS (1) The MTT assay showed a sustained, dose- and time-dependent inhibition of NB-1s exposed to ACR. (2) ACR exposure increased the phosphorylation of CaMKII and PKA, which subsequently increased the phosphorylation of Synapsin I (at Serine603 [a substrate site of CaMKII] and Serine9 [a substrate site of PKA]). Pretreatment with CaMKII and PKA inhibitors blocked the ACR-mediated increase in phosphorylation. The above-described results were all significantly different when compared to the control group (p < 0.05). (3) When co-cultured with SCs, ACR-induced NB-1 inhibition was obviously decreased, and the trend of change of phosphorylated CaMKII, PKA, and Synapsin I were changed (first slightly increased and then decreased), which was inconsistent with what we observed in NB-1s cultured alone. CONCLUSIONS The toxic effects of ACR on neurons may be mediated by CaMKII and PKA-dependent signaling pathways in which Synapsin I may act as a downstream effector. Furthermore, glial cells (SCs) may be able to prevent a certain degree of ACR-induced neuronal damage.
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Affiliation(s)
- Xiao Chen
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China
| | - Xiuhui Wang
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China
| | - Yiguang Yang
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China
| | - Zhongsheng Li
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China
| | - Yi Zhang
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China
| | - Weimin Gao
- Department of Occupational and Environmental Health Sciences, School of Public Health, West Virginia University, West Virginia, USA
| | - Jingwei Xiao
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
| | - Bin Li
- Department of Toxicology, Key Lab of Chemical Safety and Health, National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
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23
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Cruz-Lopez D, Ramos D, Castilloveitia G, Schikorski T. Quintuple labeling in the electron microscope with genetically encoded enhanced horseradish peroxidase. PLoS One 2018; 13:e0200693. [PMID: 30011315 PMCID: PMC6047818 DOI: 10.1371/journal.pone.0200693] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 07/02/2018] [Indexed: 11/25/2022] Open
Abstract
Genetic encoded multilabeling is essential for modern cell biology. In fluorescence microscopy this need has been satisfied by the development of numerous color-variants of the green fluorescent protein. In electron microscopy, however, true genetic encoded multilabeling is currently not possible. Here, we introduce combinatorial cell organelle type-specific labeling as a strategy for multilabeling. First, we created a reliable and high sensitive label by evolving the catalytic activity of horseradish peroxidase (HRP). We then built fusion proteins that targeted our new enhanced HRP (eHRP) to three cell organelles whose labeling pattern did not overlap with each other. The labeling of the endoplasmic reticulum, synaptic vesicles and the plasma membrane consequently allowed for triple labeling in the EM. The combinatorial expression of the three organelle-specific constructs increased the number of clearly distinguishable labels to seven. This strategy of multilabeling for EM closes a significant gap in our tool set and has a broad application range in cell biology.
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Affiliation(s)
- Didiana Cruz-Lopez
- Department of Neuroscience, Universidad Central del Caribe, Bayamon, Puerto Rico, United States of America
| | - Dianne Ramos
- Department of Neuroscience, Universidad Central del Caribe, Bayamon, Puerto Rico, United States of America
| | - Gloria Castilloveitia
- Department of Neuroscience, Universidad Central del Caribe, Bayamon, Puerto Rico, United States of America
| | - Thomas Schikorski
- Department of Neuroscience, Universidad Central del Caribe, Bayamon, Puerto Rico, United States of America
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24
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Batista AFR, Martínez JC, Hengst U. Intra-axonal Synthesis of SNAP25 Is Required for the Formation of Presynaptic Terminals. Cell Rep 2018; 20:3085-3098. [PMID: 28954226 DOI: 10.1016/j.celrep.2017.08.097] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/08/2017] [Accepted: 08/29/2017] [Indexed: 01/13/2023] Open
Abstract
Localized protein synthesis is a mechanism for developing axons to react acutely and in a spatially restricted manner to extracellular signals. As such, it is important for many aspects of axonal development, but its role in the formation of presynapses remains poorly understood. We found that the induced assembly of presynaptic terminals required local protein synthesis. Newly synthesized proteins were detectable at nascent presynapses within 15 min of inducing synapse formation in isolated axons. The transcript for the t-SNARE protein SNAP25, which is required for the fusion of synaptic vesicles with the plasma membrane, was recruited to presynaptic sites and locally translated. Inhibition of intra-axonal SNAP25 synthesis affected the clustering of SNAP25 and other presynaptic proteins and interfered with the release of synaptic vesicles from presynaptic sites. This study reveals a critical role for the axonal synthesis of SNAP25 in the assembly of presynaptic terminals.
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Affiliation(s)
- Andreia F R Batista
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga, Portugal; ICVS/3B's, PT Associate Laboratory, Braga/Guimarães, Portugal; The Taub Institute for Research on Alzheimer's Disease and the Aging Brain and Department of Pathology & Cell Biology, Columbia University, New York, NY 10032, USA
| | - José C Martínez
- Medical Scientist Training Program, Columbia University, New York, NY 10032, USA
| | - Ulrich Hengst
- The Taub Institute for Research on Alzheimer's Disease and the Aging Brain and Department of Pathology & Cell Biology, Columbia University, New York, NY 10032, USA.
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25
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Dunn M, Boltaev U, Beskow A, Pampou S, Realubit R, Meira T, Silva JV, Reeb R, Karan C, Jockusch S, Sulzer D, Chang YT, Sames D, Waites CL. Identification of Fluorescent Small Molecule Compounds for Synaptic Labeling by Image-Based, High-Content Screening. ACS Chem Neurosci 2018; 9:673-683. [PMID: 29215865 DOI: 10.1021/acschemneuro.7b00263] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Few tools are available for noninvasive imaging of synapses in the living mammalian brain. Current paradigms require the use of genetically modified mice or viral delivery of genetic material to the brain. To develop an alternative chemical approach, utilizing the recognition of synaptic components by organic small molecules, we designed an imaging-based, high-content screen in cultured cortical neurons to identify molecules based on their colocalization with fluorescently tagged synaptic proteins. We used this approach to screen a library of ∼7000 novel fluorescent dyes, and identified a series of compounds in the xanthone family that exhibited consistent synaptic labeling. Follow-up studies with one of these compounds, CX-G3, demonstrated its ability to label acidic organelles and in particular synaptic vesicles at glutamatergic synapses in cultured neurons and murine brain tissue, indicating the potential of this screening approach to identify promising lead compounds for use as synaptic markers, sensors, and targeting devices.
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Affiliation(s)
- Matthew Dunn
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- Neuro Technology
Center at Columbia University, New York, New York 10027, United States
- Departments of Psychiatry and Neurology, Columbia University Medical Center, New York, New York 10032, United States
| | - Umed Boltaev
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- Neuro Technology
Center at Columbia University, New York, New York 10027, United States
| | - Anne Beskow
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York 10032, United States
| | - Sergey Pampou
- Columbia Genome Center High-throughput Screening Facility, Columbia University Medical Center, New York, New York 10032, United States
| | - Ronald Realubit
- Columbia Genome Center High-throughput Screening Facility, Columbia University Medical Center, New York, New York 10032, United States
| | - Torcato Meira
- Department of Neuroscience, Columbia University Medical Center, New York, New York 10032, United States
- University of Minho, 4710-057 Braga, Portugal
| | - João Vaz Silva
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York 10032, United States
- University of Minho, 4710-057 Braga, Portugal
| | - Rose Reeb
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York 10032, United States
| | - Charles Karan
- Columbia Genome Center High-throughput Screening Facility, Columbia University Medical Center, New York, New York 10032, United States
| | - Steffen Jockusch
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - David Sulzer
- Departments of Psychiatry and Neurology, Columbia University Medical Center, New York, New York 10032, United States
| | - Young Tae Chang
- Department of Chemistry, Pohang University of Science and Technology, Pohang, Gyeongsangbuk-do, Republic of Korea
| | - Dalibor Sames
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- Neuro Technology
Center at Columbia University, New York, New York 10027, United States
| | - Clarissa L. Waites
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York 10032, United States
- Department of Neuroscience, Columbia University Medical Center, New York, New York 10032, United States
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26
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Parthier D, Kuner T, Körber C. The presynaptic scaffolding protein Piccolo organizes the readily releasable pool at the calyx of Held. J Physiol 2018; 596:1485-1499. [PMID: 29194628 DOI: 10.1113/jp274885] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 11/28/2017] [Indexed: 12/18/2022] Open
Abstract
KEY POINTS Bassoon and Piccolo do not mediate basal synaptic vesicle release at a high-frequency synapse. Knockdown of Bassoon increases short-term depression at the calyx of Held. Both Bassoon and Piccolo have shared functions in synaptic vesicle replenishment during high-frequency synaptic transmission. Piccolo organizes the readily releasable pool of synaptic vesicles. It safeguards a fraction of them to be not immediately available for action potential-induced release. This enables the synapse to sustain high-frequency synaptic transmission over long periods. ABSTRACT Synaptic vesicles (SVs) are released at the active zone (AZ), a specialized region of the presynaptic plasma membrane organized by a highly interconnected network of multidomain proteins called the cytomatrix of the active zone (CAZ). Two core components of the CAZ are the large, highly homologous scaffolding proteins Bassoon and Piccolo, whose function is not well understood. To investigate their role in synaptic transmission, we established the small hairpin RNA (shRNA)-mediated in vivo knockdown (KD) of Bassoon and Piccolo at the rat calyx of Held synapse. KD of Bassoon and Piccolo, separately or simultaneously, did not affect basic SV release. However, short-term depression (STD) was prominently increased by the KD of Bassoon, whereas KD of Piccolo only had a minor effect. The observed alterations in STD were readily explained by reduced SV replenishment in synapses deficient in either of the proteins. Thus, the regulation of SV refilling during ongoing synaptic activity is a shared function of Bassoon and Piccolo, although Bassoon appears to be more efficient. Moreover, we observed the recruitment of slowly-releasing SVs of the readily-releasable pool (RRP), which are normally not available for action potential-induced release, during high-frequency stimulation in Piccolo-deficient calyces. Therefore, the results obtained in the present study suggest a novel and specific role for Piccolo in the organization of the subpools of the RRP.
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Affiliation(s)
- Daniel Parthier
- Institute of Anatomy and Cell Biology, Department of Functional Neuroanatomy, Heidelberg University, Heidelberg, Germany.,Present address: Neuroscience Research Center, Charité Universitätsmedizin, Berlin, Germany
| | - Thomas Kuner
- Institute of Anatomy and Cell Biology, Department of Functional Neuroanatomy, Heidelberg University, Heidelberg, Germany
| | - Christoph Körber
- Institute of Anatomy and Cell Biology, Department of Functional Neuroanatomy, Heidelberg University, Heidelberg, Germany
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27
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Badawi Y, Nishimune H. Presynaptic active zones of mammalian neuromuscular junctions: Nanoarchitecture and selective impairments in aging. Neurosci Res 2017; 127:78-88. [PMID: 29221906 DOI: 10.1016/j.neures.2017.11.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 11/17/2017] [Accepted: 11/27/2017] [Indexed: 12/16/2022]
Abstract
Neurotransmitter release occurs at active zones, which are specialized regions of the presynaptic membrane. A dense collection of proteins at the active zone provides a platform for molecular interactions that promote recruitment, docking, and priming of synaptic vesicles. At mammalian neuromuscular junctions (NMJs), muscle-derived laminin β2 interacts with presynaptic voltage-gated calcium channels to organize active zones. The molecular architecture of presynaptic active zones has been revealed using super-resolution microscopy techniques that combine nanoscale resolution and multiple molecular identification. Interestingly, the active zones of adult NMJs are not stable structures and thus become impaired during aging due to the selective degeneration of specific active zone proteins. This review will discuss recent progress in the understanding of active zone nanoarchitecture and the mechanisms underlying active zone organization in mammalian NMJs. Furthermore, we will summarize the age-related degeneration of active zones at NMJs, and the role of exercise in maintaining active zones.
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Affiliation(s)
- Yomna Badawi
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS, 66160, USA
| | - Hiroshi Nishimune
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS, 66160, USA.
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28
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Xuan Z, Manning L, Nelson J, Richmond JE, Colón-Ramos DA, Shen K, Kurshan PT. Clarinet (CLA-1), a novel active zone protein required for synaptic vesicle clustering and release. eLife 2017; 6:29276. [PMID: 29160205 PMCID: PMC5728718 DOI: 10.7554/elife.29276] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Accepted: 11/20/2017] [Indexed: 01/03/2023] Open
Abstract
Active zone proteins cluster synaptic vesicles at presynaptic terminals and coordinate their release. In forward genetic screens, we isolated a novel Caenorhabditis elegans active zone gene, clarinet (cla-1). cla-1 mutants exhibit defects in synaptic vesicle clustering, active zone structure and synapse number. As a result, they have reduced spontaneous vesicle release and increased synaptic depression. cla-1 mutants show defects in vesicle distribution near the presynaptic dense projection, with fewer undocked vesicles contacting the dense projection and more docked vesicles at the plasma membrane. cla-1 encodes three isoforms containing common C-terminal PDZ and C2 domains with homology to vertebrate active zone proteins Piccolo and RIM. The C-termini of all isoforms localize to the active zone. Specific loss of the ~9000 amino acid long isoform results in vesicle clustering defects and increased synaptic depression. Our data indicate that specific isoforms of clarinet serve distinct functions, regulating synapse development, vesicle clustering and release.
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Affiliation(s)
- Zhao Xuan
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States.,Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Yale University School of Medicine, New Haven, United States
| | - Laura Manning
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Jessica Nelson
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States.,Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Yale University School of Medicine, New Haven, United States
| | - Janet E Richmond
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Daniel A Colón-Ramos
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States.,Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Yale University School of Medicine, New Haven, United States.,Instituto de Neurobiología, Recinto de Ciencias Médicas, Universidad de Puerto Rico, San Juan, Puerto Rico
| | - Kang Shen
- Department of Biology, Stanford University, Stanford, United States.,Howard Hughes Medical Institute
| | - Peri T Kurshan
- Department of Biology, Stanford University, Stanford, United States
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29
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Butola T, Wichmann C, Moser T. Piccolo Promotes Vesicle Replenishment at a Fast Central Auditory Synapse. Front Synaptic Neurosci 2017; 9:14. [PMID: 29118709 PMCID: PMC5660988 DOI: 10.3389/fnsyn.2017.00014] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 10/09/2017] [Indexed: 12/20/2022] Open
Abstract
Piccolo and Bassoon are the two largest cytomatrix of the active zone (CAZ) proteins involved in scaffolding and regulating neurotransmitter release at presynaptic active zones (AZs), but have long been discussed as being functionally redundant. We employed genetic manipulation to bring forth and segregate the role of Piccolo from that of Bassoon at central auditory synapses of the cochlear nucleus—the endbulbs of Held. These synapses specialize in high frequency synaptic transmission, ideally poised to reveal even subtle deficits in the regulation of neurotransmitter release upon molecular perturbation. Combining semi-quantitative immunohistochemistry, electron microscopy, and in vitro and in vivo electrophysiology we first studied signal transmission in Piccolo-deficient mice. Our analysis was not confounded by a cochlear deficit, as a short isoform of Piccolo (“Piccolino”) present at the upstream ribbon synapses of cochlear inner hair cells (IHC), is unaffected by the mutation. Disruption of Piccolo increased the abundance of Bassoon at the AZs of endbulbs, while that of RIM1 was reduced and other CAZ proteins remained unaltered. Presynaptic fiber stimulation revealed smaller amplitude of the evoked excitatory postsynaptic currents (eEPSC), while eEPSC kinetics as well as miniature EPSCs (mEPSCs) remained unchanged. Cumulative analysis of eEPSC trains indicated that the reduced eEPSC amplitude of Piccolo-deficient endbulb synapses is primarily due to a reduced readily releasable pool (RRP) of synaptic vesicles (SV), as was corroborated by a reduction of vesicles at the AZ found on an ultrastructural level. Release probability seemed largely unaltered. Recovery from short-term depression was slowed. We then performed a physiological analysis of endbulb synapses from mice which, in addition to Piccolo deficiency, lacked one functional allele of the Bassoon gene. Analysis of the double-mutant endbulbs revealed an increase in release probability, while the synapses still exhibited the reduced RRP, and the impairment in SV replenishment was exacerbated. We propose additive roles of Piccolo and Bassoon in SV replenishment which in turn influences the organization and size of the RRP, and an additional role of Bassoon in regulation of release probability.
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Affiliation(s)
- Tanvi Butola
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences (GGNB), University of Göttingen, Göttingen, Germany.,International Max Planck Research School for Neurosciences (IMPRS), Göttingen, Germany.,Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry (MPG), Göttingen, Germany
| | - Carolin Wichmann
- Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences (GGNB), University of Göttingen, Göttingen, Germany.,Collaborative Research Centers 889 and 1286, University of Göttingen, Göttingen, Germany.,Molecular Architecture of Synapses Group, Center for Biostructural Imaging of Neurodegeneration (BIN), University of Göttingen, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences (GGNB), University of Göttingen, Göttingen, Germany.,International Max Planck Research School for Neurosciences (IMPRS), Göttingen, Germany.,Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry (MPG), Göttingen, Germany.,Collaborative Research Centers 889 and 1286, University of Göttingen, Göttingen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany
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30
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Parkin Deficiency Reduces Hippocampal Glutamatergic Neurotransmission by Impairing AMPA Receptor Endocytosis. J Neurosci 2017; 36:12243-12258. [PMID: 27903732 DOI: 10.1523/jneurosci.1473-16.2016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 09/19/2016] [Accepted: 10/18/2016] [Indexed: 12/20/2022] Open
Abstract
Mutations in the gene encoding Parkin, an E3 ubiquitin ligase, lead to juvenile-onset Parkinson's disease by inducing the selective death of midbrain dopaminergic neurons. Accumulating evidence indicates that Parkin also has an important role in excitatory glutamatergic neurotransmission, although its precise mechanism of action remains unclear. Here, we investigate Parkin's role at glutamatergic synapses of rat hippocampal neurons. We find that Parkin-deficient neurons exhibit significantly reduced AMPA receptor (AMPAR)-mediated currents and cell-surface expression, and that these phenotypes result from decreased postsynaptic expression of the adaptor protein Homer1, which is necessary for coupling AMPAR endocytic zones with the postsynaptic density. Accordingly, Parkin loss of function leads to the reduced density of postsynaptic endocytic zones and to impaired AMPAR internalization. These findings demonstrate a novel and essential role for Parkin in glutamatergic neurotransmission, as a stabilizer of postsynaptic Homer1 and the Homer1-linked endocytic machinery necessary for maintaining normal cell-surface AMPAR levels. SIGNIFICANCE STATEMENT Mutations in Parkin, a ubiquitinating enzyme, lead to the selective loss of midbrain dopaminergic neurons and juvenile-onset Parkinson's disease (PD). Parkin loss of function has also been shown to alter hippocampal glutamatergic neurotransmission, providing a potential explanation for PD-associated cognitive impairment. However, very little is known about Parkin's specific sites or mechanisms of action at glutamatergic synapses. Here, we show that Parkin deficiency leads to decreased AMPA receptor-mediated activity due to disruption of the postsynaptic endocytic zones required for maintaining proper cell-surface AMPA receptor levels. These findings demonstrate a novel role for Parkin in synaptic AMPA receptor internalization and suggest a Parkin-dependent mechanism for hippocampal dysfunction that may explain cognitive deficits associated with some forms of PD.
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31
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Shank3 Is Part of a Zinc-Sensitive Signaling System That Regulates Excitatory Synaptic Strength. J Neurosci 2017; 36:9124-34. [PMID: 27581454 DOI: 10.1523/jneurosci.0116-16.2016] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 07/08/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Shank3 is a multidomain scaffold protein localized to the postsynaptic density of excitatory synapses. Functional studies in vivo and in vitro support the concept that Shank3 is critical for synaptic plasticity and the trans-synaptic coupling between the reliability of presynaptic neurotransmitter release and postsynaptic responsiveness. However, how Shank3 regulates synaptic strength remains unclear. The C terminus of Shank3 contains a sterile alpha motif (SAM) domain that is essential for its postsynaptic localization and also binds zinc, thus raising the possibility that changing zinc levels modulate Shank3 function in dendritic spines. In support of this hypothesis, we find that zinc is a potent regulator of Shank3 activation and dynamics in rat hippocampal neurons. Moreover, we show that zinc modulation of synaptic transmission is Shank3 dependent. Interestingly, an autism spectrum disorder (ASD)-associated variant of Shank3 (Shank3(R87C)) retains its zinc sensitivity and supports zinc-dependent activation of AMPAR-mediated synaptic transmission. However, elevated zinc was unable to rescue defects in trans-synaptic signaling caused by the R87C mutation, implying that trans-synaptic increases in neurotransmitter release are not necessary for the postsynaptic effects of zinc. Together, these data suggest that Shank3 is a key component of a zinc-sensitive signaling system, regulating synaptic strength that may be impaired in ASD. SIGNIFICANCE STATEMENT Shank3 is a postsynaptic protein associated with neurodevelopmental disorders such as autism and schizophrenia. In this study, we show that Shank3 is a key component of a zinc-sensitive signaling system that regulates excitatory synaptic transmission. Intriguingly, an autism-associated mutation in Shank3 partially impairs this signaling system. Therefore, perturbation of zinc homeostasis may impair, not only synaptic functionality and plasticity, but also may lead to cognitive and behavioral abnormalities seen in patients with psychiatric disorders.
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32
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Activity-Dependent Degradation of Synaptic Vesicle Proteins Requires Rab35 and the ESCRT Pathway. J Neurosci 2017; 36:8668-86. [PMID: 27535913 DOI: 10.1523/jneurosci.0725-16.2016] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 06/29/2016] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED Synaptic vesicle (SV) pools must maintain a functional repertoire of proteins to efficiently release neurotransmitter. The accumulation of old or damaged proteins on SV membranes is linked to synaptic dysfunction and neurodegeneration. However, despite the importance of SV protein turnover for neuronal health, the molecular mechanisms underlying this process are largely unknown. Here, we have used dissociated rat hippocampal neurons to investigate the pathway for SV protein degradation. We find that neuronal activity drives the degradation of a subset of SV proteins and that the endosomal sorting complex required for transport (ESCRT) machinery and SV-associated GTPase Rab35 are key elements of this use-dependent degradative pathway. Specifically, neuronal activity induces Rab35 activation and binding to the ESCRT-0 protein Hrs, which we have identified as a novel Rab35 effector. These actions recruit the downstream ESCRT machinery to SV pools, thereby initiating SV protein degradation via the ESCRT pathway. Our findings show that the Rab35/ESCRT pathway facilitates the activity-dependent removal of specific proteins from SV pools, thereby maintaining presynaptic protein homeostasis. SIGNIFICANCE STATEMENT Synaptic transmission is mediated by the release of chemical neurotransmitters from synaptic vesicles (SVs). This tightly regulated process requires a functional pool of SVs, necessitating cellular mechanisms for removing old or damaged proteins that could impair SV cycling. Here, we show that a subset of SV proteins is degraded in an activity-dependent manner and that key steps in this degradative pathway are the activation of the small GTPase Rab35 and the subsequent recruitment of the endosomal sorting complex required for transport (ESCRT) machinery to SV pools. Further, we demonstrate that ESCRT-0 component Hrs is an effector of Rab35, thus providing novel mechanistic insight into the coupling of neuronal activity with SV protein degradation and the maintenance of functional SV pools.
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33
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Torres VI, Inestrosa NC. Vertebrate Presynaptic Active Zone Assembly: a Role Accomplished by Diverse Molecular and Cellular Mechanisms. Mol Neurobiol 2017; 55:4513-4528. [PMID: 28685386 DOI: 10.1007/s12035-017-0661-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 06/14/2017] [Indexed: 01/22/2023]
Abstract
Among all the biological systems in vertebrates, the central nervous system (CNS) is the most complex, and its function depends on specialized contacts among neurons called synapses. The assembly and organization of synapses must be exquisitely regulated for a normal brain function and network activity. There has been a tremendous effort in recent decades to understand the molecular and cellular mechanisms participating in the formation of new synapses and their organization, maintenance, and regulation. At the vertebrate presynapses, proteins such as Piccolo, Bassoon, RIM, RIM-BPs, CAST/ELKS, liprin-α, and Munc13 are constant residents and participate in multiple and dynamic interactions with other regulatory proteins, which define network activity and normal brain function. Here, we review the function of these active zone (AZ) proteins and diverse factors involved in AZ assembly and maintenance, with an emphasis on axonal trafficking of precursor vesicles, protein homo- and hetero-oligomeric interactions as a mechanism of AZ trapping and stabilization, and the role of F-actin in presynaptic assembly and its modulation by Wnt signaling.
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Affiliation(s)
- Viviana I Torres
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Nibaldo C Inestrosa
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile. .,Center for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, Australia. .,Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile.
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Goodman L, Baddeley D, Ambroziak W, Waites CL, Garner CC, Soeller C, Montgomery JM. N-terminal SAP97 isoforms differentially regulate synaptic structure and postsynaptic surface pools of AMPA receptors. Hippocampus 2017; 27:668-682. [PMID: 28244171 DOI: 10.1002/hipo.22723] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 02/02/2017] [Accepted: 02/17/2017] [Indexed: 11/07/2022]
Abstract
The location and density of postsynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors is controlled by scaffolding proteins within the postsynaptic density (PSD). SAP97 is a PSD protein with two N-terminal isoforms, α and β, that have opposing effects on synaptic strength thought to result from differential targeting of AMPA receptors into distinct synaptic versus extrasynaptic locations, respectively. In this study, we have applied dSTORM super resolution imaging in order to localize the synaptic and extrasynaptic pools of AMPA receptors in neurons expressing α or βSAP97. Unexpectedly, we observed that both α and βSAP97 enhanced the localization of AMPA receptors at synapses. However, this occurred via different mechanisms: αSAP97 increased PSD size and consequently the number of receptor binding sites, whilst βSAP97 increased synaptic receptor cluster size and surface AMPA receptor density at the PSD edge and surrounding perisynaptic sites without changing PSD size. αSAP97 also strongly enlarged presynaptic active zone protein clusters, consistent with both presynaptic and postsynaptic enhancement underlying the previously observed αSAP97-induced increase in AMPA receptor-mediated currents. In contrast, βSAP97-expressing neurons increased the proportion of immature filopodia that express higher levels of AMPA receptors, decreased the number of functional presynaptic terminals, and also reduced the size of the dendritic tree and delayed the maturation of mushroom spines. Our data reveal that SAP97 isoforms can specifically regulate surface AMPA receptor nanodomain clusters, with βSAP97 increasing extrasynaptic receptor domains at peri-synaptic and filopodial sites. Moreover, βSAP97 negatively regulates synaptic maturation both structurally and functionally. These data support diverging presynaptic and postsynaptic roles of SAP97 N-terminal isoforms in synapse maturation and plasticity. As numerous splice isoforms exist in other major PSD proteins (e.g., Shank, PSD95, and SAP102), this alternative splicing may result in individual PSD proteins having divergent functional and structural roles in both physiological and pathophysiological synaptic states.
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Affiliation(s)
- Lucy Goodman
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - David Baddeley
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand.,Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut
| | - Wojciech Ambroziak
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Clarissa L Waites
- Department of Pathology and Cell Biology, Columbia University, New York, New York
| | - Craig C Garner
- German Center for Neurodegenerative Diseases, Charité University, Berlin, Germany
| | - Christian Soeller
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand.,Department of Physical and Cell Biology, Physical and Cell Biology, University of Exeter, Exeter, United Kingdom
| | - Johanna M Montgomery
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand
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35
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Okerlund ND, Schneider K, Leal-Ortiz S, Montenegro-Venegas C, Kim SA, Garner LC, Waites CL, Gundelfinger ED, Reimer RJ, Garner CC. Bassoon Controls Presynaptic Autophagy through Atg5. Neuron 2017; 93:897-913.e7. [DOI: 10.1016/j.neuron.2017.01.026] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 06/28/2016] [Accepted: 01/25/2017] [Indexed: 12/22/2022]
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Terry-Lorenzo RT, Torres VI, Wagh D, Galaz J, Swanson SK, Florens L, Washburn MP, Waites CL, Gundelfinger ED, Reimer RJ, Garner CC. Trio, a Rho Family GEF, Interacts with the Presynaptic Active Zone Proteins Piccolo and Bassoon. PLoS One 2016; 11:e0167535. [PMID: 27907191 PMCID: PMC5132261 DOI: 10.1371/journal.pone.0167535] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 11/15/2016] [Indexed: 12/17/2022] Open
Abstract
Synaptic vesicles (SVs) fuse with the plasma membrane at a precise location called the presynaptic active zone (AZ). This fusion is coordinated by proteins embedded within a cytoskeletal matrix assembled at the AZ (CAZ). In the present study, we have identified a novel binding partner for the CAZ proteins Piccolo and Bassoon. This interacting protein, Trio, is a member of the Dbl family of guanine nucleotide exchange factors (GEFs) known to regulate the dynamic assembly of actin and growth factor dependent axon guidance and synaptic growth. Trio was found to interact with the C-terminal PBH 9/10 domains of Piccolo and Bassoon via its own N-terminal Spectrin repeats, a domain that is also critical for its localization to the CAZ. Moreover, our data suggest that regions within the C-terminus of Trio negatively regulate its interactions with Piccolo/Bassoon. These findings provide a mechanism for the presynaptic targeting of Trio and support a model in which Piccolo and Bassoon play a role in regulating neurotransmission through interactions with proteins, including Trio, that modulate the dynamic assembly of F-actin during cycles of synaptic vesicle exo- and endocytosis.
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Affiliation(s)
- Ryan T. Terry-Lorenzo
- Dept. of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, California, United States of America
| | - Viviana I. Torres
- Dept. of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, California, United States of America
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile, Alameda, Santiago, Chile
| | - Dhananjay Wagh
- Dept. of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, California, United States of America
| | - Jose Galaz
- Dept. of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, California, United States of America
| | - Selene K. Swanson
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Laurence Florens
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Michael P. Washburn
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Clarissa L. Waites
- Dept. of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, California, United States of America
| | - Eckart D. Gundelfinger
- Dept. of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Richard J. Reimer
- Dept. of Neurology and Neurological Sciences Stanford University and Veterans Affairs Palo Alto Health Care System, Palo Alto, California, United States of America
| | - Craig C. Garner
- Dept. of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, California, United States of America
- German Centers for Neurodegenerative Diseases, Charité - Medical University, Berlin, Germany
- * E-mail:
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Dvorkin R, Ziv NE. Relative Contributions of Specific Activity Histories and Spontaneous Processes to Size Remodeling of Glutamatergic Synapses. PLoS Biol 2016; 14:e1002572. [PMID: 27776122 PMCID: PMC5077109 DOI: 10.1371/journal.pbio.1002572] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Accepted: 09/27/2016] [Indexed: 11/18/2022] Open
Abstract
The idea that synaptic properties are defined by specific pre- and postsynaptic activity histories is one of the oldest and most influential tenets of contemporary neuroscience. Recent studies also indicate, however, that synaptic properties often change spontaneously, even in the absence of specific activity patterns or any activity whatsoever. What, then, are the relative contributions of activity history-dependent and activity history-independent processes to changes synapses undergo? To compare the relative contributions of these processes, we imaged, in spontaneously active networks of cortical neurons, glutamatergic synapses formed between the same axons and neurons or dendrites under the assumption that their similar activity histories should result in similar size changes over timescales of days. The size covariance of such commonly innervated (CI) synapses was then compared to that of synapses formed by different axons (non-CI synapses) that differed in their activity histories. We found that the size covariance of CI synapses was greater than that of non-CI synapses; yet overall size covariance of CI synapses was rather modest. Moreover, momentary and time-averaged sizes of CI synapses correlated rather poorly, in perfect agreement with published electron microscopy-based measurements of mouse cortex synapses. A conservative estimate suggested that ~40% of the observed size remodeling was attributable to specific activity histories, whereas ~10% and ~50% were attributable to cell-wide and spontaneous, synapse-autonomous processes, respectively. These findings demonstrate that histories of naturally occurring activity patterns can direct glutamatergic synapse remodeling but also suggest that the contributions of spontaneous, possibly stochastic, processes are at least as great.
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Affiliation(s)
- Roman Dvorkin
- Technion Faculty of Medicine, Network Biology Research Laboratories, Lorry Lokey Center for Life Sciences and Engineering, Technion, Haifa, Israel
| | - Noam E Ziv
- Technion Faculty of Medicine, Network Biology Research Laboratories, Lorry Lokey Center for Life Sciences and Engineering, Technion, Haifa, Israel.,Rappaport Family Institute for Research in the Medical Sciences, Haifa, Israel
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Rogers RS, Nishimune H. The role of laminins in the organization and function of neuromuscular junctions. Matrix Biol 2016; 57-58:86-105. [PMID: 27614294 DOI: 10.1016/j.matbio.2016.08.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 08/10/2016] [Accepted: 08/17/2016] [Indexed: 01/11/2023]
Abstract
The synapse between motor neurons and skeletal muscle is known as the neuromuscular junction (NMJ). Proper alignment of presynaptic and post-synaptic structures of motor neurons and muscle fibers, respectively, is essential for efficient motor control of skeletal muscles. The synaptic cleft between these two cells is filled with basal lamina. Laminins are heterotrimer extracellular matrix molecules that are key members of the basal lamina. Laminin α4, α5, and β2 chains specifically localize to NMJs, and these laminin isoforms play a critical role in maintenance of NMJs and organization of synaptic vesicle release sites known as active zones. These individual laminin chains exert their role in organizing NMJs by binding to their receptors including integrins, dystroglycan, and voltage-gated calcium channels (VGCCs). Disruption of these laminins or the laminin-receptor interaction occurs in neuromuscular diseases including Pierson syndrome and Lambert-Eaton myasthenic syndrome (LEMS). Interventions to maintain proper level of laminins and their receptor interactions may be insightful in treating neuromuscular diseases and aging related degeneration of NMJs.
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Affiliation(s)
- Robert S Rogers
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, Kansas, USA.
| | - Hiroshi Nishimune
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, Kansas, USA.
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A DNA target-enrichment approach to detect mutations, copy number changes and immunoglobulin translocations in multiple myeloma. Blood Cancer J 2016; 6:e467. [PMID: 27588520 PMCID: PMC5056967 DOI: 10.1038/bcj.2016.72] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 05/25/2016] [Accepted: 06/16/2016] [Indexed: 01/31/2023] Open
Abstract
Genomic lesions are not investigated during routine diagnostic workup for multiple myeloma (MM). Cytogenetic studies are performed to assess prognosis but with limited impact on therapeutic decisions. Recently, several recurrently mutated genes have been described, but their clinical value remains to be defined. Therefore, clinical-grade strategies to investigate the genomic landscape of myeloma samples are needed to integrate new and old prognostic markers. We developed a target-enrichment strategy followed by next-generation sequencing (NGS) to streamline simultaneous analysis of gene mutations, copy number changes and immunoglobulin heavy chain (IGH) translocations in MM in a high-throughput manner, and validated it in a panel of cell lines. We identified 548 likely oncogenic mutations in 182 genes. By integrating published data sets of NGS in MM, we retrieved a list of genes with significant relevance to myeloma and found that the mutational spectrum of primary samples and MM cell lines is partially overlapping. Gains and losses of chromosomes, chromosomal segments and gene loci were identified with accuracy comparable to conventional arrays, allowing identification of lesions with known prognostic significance. Furthermore, we identified IGH translocations with high positive and negative predictive value. Our approach could allow the identification of novel biomarkers with clinical relevance in myeloma.
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40
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Dual-color STED microscopy reveals a sandwich structure of Bassoon and Piccolo in active zones of adult and aged mice. Sci Rep 2016; 6:27935. [PMID: 27321892 PMCID: PMC4913281 DOI: 10.1038/srep27935] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 05/16/2016] [Indexed: 11/08/2022] Open
Abstract
Presynaptic active zones play a pivotal role as synaptic vesicle release sites for synaptic transmission, but the molecular architecture of active zones in mammalian neuromuscular junctions (NMJs) at sub-diffraction limited resolution remains unknown. Bassoon and Piccolo are active zone specific cytosolic proteins essential for active zone assembly in NMJs, ribbon synapses, and brain synapses. These proteins are thought to colocalize and share some functions at active zones. Here, we report an unexpected finding of non-overlapping localization of these two proteins in mouse NMJs revealed using dual-color stimulated emission depletion (STED) super resolution microscopy. Piccolo puncta sandwiched Bassoon puncta and aligned in a Piccolo-Bassoon-Piccolo structure in adult NMJs. P/Q-type voltage-gated calcium channel (VGCC) puncta colocalized with Bassoon puncta. The P/Q-type VGCC and Bassoon protein levels decreased significantly in NMJs from aged mouse. In contrast, the Piccolo levels in NMJs from aged mice were comparable to levels in adult mice. This study revealed the molecular architecture of active zones in mouse NMJs at sub-diffraction limited resolution, and described the selective degeneration mechanism of active zone proteins in NMJs from aged mice. Interestingly, the localization pattern of active zone proteins described herein is similar to active zone structures described using electron microscope tomography.
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Lopez CI, Saud KE, Aguilar R, Berndt FA, Cánovas J, Montecino M, Kukuljan M. The chromatin modifying complex CoREST/LSD1 negatively regulates notch pathway during cerebral cortex development. Dev Neurobiol 2016; 76:1360-1373. [PMID: 27112428 DOI: 10.1002/dneu.22397] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 03/19/2016] [Accepted: 04/22/2016] [Indexed: 12/22/2022]
Abstract
The development of the cerebral cortex is a dynamic and coordinated process in which cell division, cell death, migration, and differentiation must be highly regulated to acquire the final architecture and functional competence of the mature organ. Notch pathway is an important regulator of differentiation and it is essential to maintain neural stem cell (NSC) pool. Here, we studied the role of epigenetic modulators such as lysine-specific demethylase 1 (LSD1) and its interactor CoREST in the regulation of the Notch pathway activity during the development of the cerebral cortex. We found that CoREST and LSD1 interact in vitro with RBPJ-κ in the repressor complex and these proteins are released upon overexpression of Notch intracellular domain (NICD). We corroborated LSD1 and RBPJ-κ interaction in developing cerebral cortex and also found that LSD1 binds to the hes1 promoter. Knock-down of CoREST and LSD1 by in utero electroporation increases Hes1 expression in vivo and decreases Ngn2. Interestingly, we found a functional interaction between CoREST and LSD1 with Notch pathway. This conclusion is based on the observation that both the defects in neuronal migration and the increase in the number of cells expressing Sox2 and Tbr2 were associated to the knock-down of either CoREST or LSD1 and were reversed by the loss of Notch. These results demonstrate that CoREST and LSD1 downregulate the Notch pathway in the developing cerebral cortex, thus suggesting a role of epigenetic regulation in the fine tuning of cell differentiation. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1360-1373, 2016.
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Affiliation(s)
- Cecilia I Lopez
- Faculty of Medicine, Program in Physiology and Biophysics, Institute for Biomedical Sciences, Universidad de Chile, Santiago, Chile.,Faculty of Medicine, Biomedical Neuroscience Institute (BNI), Universidad de Chile, Santiago, Chile
| | - Katherine E Saud
- Faculty of Medicine, Program in Physiology and Biophysics, Institute for Biomedical Sciences, Universidad de Chile, Santiago, Chile.,Faculty of Medicine, Biomedical Neuroscience Institute (BNI), Universidad de Chile, Santiago, Chile
| | - Rodrigo Aguilar
- Faculty of Biological Sciences and Faculty of Medicine, Center for Biomedical Research and FONDAP Center for Genome Regulation, Universidad Andre's Bello, Santiago, Chile
| | - F Andrés Berndt
- Faculty of Medicine, Program in Physiology and Biophysics, Institute for Biomedical Sciences, Universidad de Chile, Santiago, Chile.,Faculty of Medicine, Biomedical Neuroscience Institute (BNI), Universidad de Chile, Santiago, Chile
| | - José Cánovas
- Faculty of Medicine, Program in Physiology and Biophysics, Institute for Biomedical Sciences, Universidad de Chile, Santiago, Chile.,Faculty of Medicine, Biomedical Neuroscience Institute (BNI), Universidad de Chile, Santiago, Chile
| | - Martín Montecino
- Faculty of Biological Sciences and Faculty of Medicine, Center for Biomedical Research and FONDAP Center for Genome Regulation, Universidad Andre's Bello, Santiago, Chile
| | - Manuel Kukuljan
- Faculty of Medicine, Program in Physiology and Biophysics, Institute for Biomedical Sciences, Universidad de Chile, Santiago, Chile.,Faculty of Medicine, Biomedical Neuroscience Institute (BNI), Universidad de Chile, Santiago, Chile
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42
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Piccolo paralogs and orthologs display conserved patterns of alternative splicing within the C2A and C2B domains. Genes Genomics 2016. [DOI: 10.1007/s13258-015-0383-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Körber C, Kuner T. Molecular Machines Regulating the Release Probability of Synaptic Vesicles at the Active Zone. Front Synaptic Neurosci 2016; 8:5. [PMID: 26973506 PMCID: PMC4773589 DOI: 10.3389/fnsyn.2016.00005] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 02/17/2016] [Indexed: 11/13/2022] Open
Abstract
The fusion of synaptic vesicles (SVs) with the plasma membrane of the active zone (AZ) upon arrival of an action potential (AP) at the presynaptic compartment is a tightly regulated probabilistic process crucial for information transfer. The probability of a SV to release its transmitter content in response to an AP, termed release probability (Pr), is highly diverse both at the level of entire synapses and individual SVs at a given synapse. Differences in Pr exist between different types of synapses, between synapses of the same type, synapses originating from the same axon and even between different SV subpopulations within the same presynaptic terminal. The Pr of SVs at the AZ is set by a complex interplay of different presynaptic properties including the availability of release-ready SVs, the location of the SVs relative to the voltage-gated calcium channels (VGCCs) at the AZ, the magnitude of calcium influx upon arrival of the AP, the buffering of calcium ions as well as the identity and sensitivity of the calcium sensor. These properties are not only interconnected, but can also be regulated dynamically to match the requirements of activity patterns mediated by the synapse. Here, we review recent advances in identifying molecules and molecular machines taking part in the determination of vesicular Pr at the AZ.
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Affiliation(s)
- Christoph Körber
- Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University Heidelberg, Germany
| | - Thomas Kuner
- Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University Heidelberg, Germany
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Gundelfinger ED, Reissner C, Garner CC. Role of Bassoon and Piccolo in Assembly and Molecular Organization of the Active Zone. Front Synaptic Neurosci 2016; 7:19. [PMID: 26793095 PMCID: PMC4709825 DOI: 10.3389/fnsyn.2015.00019] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 12/14/2015] [Indexed: 01/05/2023] Open
Abstract
Bassoon and Piccolo are two very large scaffolding proteins of the cytomatrix assembled at the active zone (CAZ) where neurotransmitter is released. They share regions of high sequence similarity distributed along their entire length and seem to share both overlapping and distinct functions in organizing the CAZ. Here, we survey our present knowledge on protein-protein interactions and recent progress in understanding of molecular functions of these two giant proteins. These include roles in the assembly of active zones (AZ), the localization of voltage-gated Ca2+ channels (VGCCs) in the vicinity of release sites, synaptic vesicle (SV) priming and in the case of Piccolo, a role in the dynamic assembly of the actin cytoskeleton. Piccolo and Bassoon are also important for the maintenance of presynaptic structure and function, as well as for the assembly of CAZ specializations such as synaptic ribbons. Recent findings suggest that they are also involved in the regulation activity-dependent communication between presynaptic boutons and the neuronal nucleus. Together these observations suggest that Bassoon and Piccolo use their modular structure to organize super-molecular complexes essential for various aspects of presynaptic function.
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Affiliation(s)
- Eckart D Gundelfinger
- Department Neurochemistry and Molecular Biology, Leibniz Institute for NeurobiologyMagdeburg, Germany; Center for Behavioral Brain SciencesMagdeburg, Germany; Medical Faculty, Otto von Guericke UniversityMagdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE) Site MagdeburgMagdeburg, Germany
| | - Carsten Reissner
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms University Münster, Germany
| | - Craig C Garner
- German Center for Neurodegenerative Diseases (DZNE) Site BerlinBerlin, Germany; Charité Medical UniversityBerlin, Germany
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Ryan J, Artero S, Carrière I, Maller JJ, Meslin C, Ritchie K, Ancelin ML. GWAS-identified risk variants for major depressive disorder: Preliminary support for an association with late-life depressive symptoms and brain structural alterations. Eur Neuropsychopharmacol 2016; 26:113-125. [PMID: 26391493 DOI: 10.1016/j.euroneuro.2015.08.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 08/28/2015] [Accepted: 08/29/2015] [Indexed: 11/30/2022]
Abstract
A number of genome-wide association studies (GWAS) have investigated risk factors for major depressive disorder (MDD), however there has been little attempt to replicate these findings in population-based studies of depressive symptoms. Variants within three genes, BICC1, PCLO and GRM7 were selected for replication in our study based on the following criteria: they were identified in a prior MDD GWAS study; a subsequent study found evidence that they influenced depression risk; and there is a solid biological basis for a role in depression. We firstly investigated whether these variants were associated with depressive symptoms in our population-based cohort of 929 elderly (238 with clinical depressive symptoms and 691 controls), and secondly to investigate associations with structural brain alterations. A number of nominally significant associations were identified, but none reached Bonferroni-corrected significance levels. Common SNPs in BICC1 and PCLO were associated with a 50% and 30% decreased risk of depression, respectively. PCLO rs2522833 was also associated with the volume of grey matter (p=1.6×10(-3)), and to a lesser extent with hippocampal volume and white matter lesions. Among depressed individuals rs9870680 (GRM7) was associated with the volume of grey and white matter (p=10(-4) and 8.3×10(-3), respectively). Our results provide some support for the involvement of BICC1 and PCLO in late-life depressive disorders and preliminary evidence that these genetic variants may also influence brain structural volumes. However effect sizes remain modest and associations did not reach corrected significance levels. Further large imaging studies are needed to confirm our findings.
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Affiliation(s)
- Joanne Ryan
- Inserm, U1061, Montpellier F-34093; Université Montpellier, Montpellier F-34000, France; Disease Epigenetics Group, Murdoch Childrens Research Institute & Department of Paediatrics, University of Melbourne, Parkville 3052, Victoria, Australia.
| | - Sylvaine Artero
- Inserm, U1061, Montpellier F-34093; Université Montpellier, Montpellier F-34000, France
| | - Isabelle Carrière
- Inserm, U1061, Montpellier F-34093; Université Montpellier, Montpellier F-34000, France
| | - Jerome J Maller
- Monash Alfred Psychiatry Research Centre, The Alfred & Monash University Central Clinical School, Melbourne 3004, Victoria, Australia
| | - Chantal Meslin
- Centre for Mental Health Research, Australian National University, ACT, Canberra 0200, Australia
| | - Karen Ritchie
- Inserm, U1061, Montpellier F-34093; Université Montpellier, Montpellier F-34000, France; Faculty of Medicine, Imperial College, London SW7 2AZ, United Kingdom
| | - Marie-Laure Ancelin
- Inserm, U1061, Montpellier F-34093; Université Montpellier, Montpellier F-34000, France
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46
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The Specification of Cortical Subcerebral Projection Neurons Depends on the Direct Repression of TBR1 by CTIP1/BCL11a. J Neurosci 2015; 35:7552-64. [PMID: 25972180 DOI: 10.1523/jneurosci.0169-15.2015] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The acquisition of distinct neuronal fates is fundamental for the function of the cerebral cortex. We find that the development of subcerebral projections from layer 5 neurons in the mouse neocortex depends on the high levels of expression of the transcription factor CTIP1; CTIP1 is coexpressed with CTIP2 in neurons that project to subcerebral targets and with SATB2 in those that project to the contralateral cortex. CTIP1 directly represses Tbr1 in layer 5, which appears as a critical step for the acquisition of the subcerebral fate. In contrast, lower levels of CTIP1 in layer 6 are required for TBR1 expression, which directs the corticothalamic fate. CTIP1 does not appear to play a critical role in the acquisition of the callosal projection fate in layer 5. These findings unravel a key step in the acquisition of cell fate for closely related corticofugal neurons and indicate that differential dosages of transcriptions factors are critical to specify different neuronal identities.
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47
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Wichmann C, Moser T. Relating structure and function of inner hair cell ribbon synapses. Cell Tissue Res 2015; 361:95-114. [PMID: 25874597 PMCID: PMC4487357 DOI: 10.1007/s00441-014-2102-7] [Citation(s) in RCA: 74] [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: 10/02/2014] [Accepted: 12/18/2014] [Indexed: 01/28/2023]
Abstract
In the mammalian cochlea, sound is encoded at synapses between inner hair cells (IHCs) and type I spiral ganglion neurons (SGNs). Each SGN receives input from a single IHC ribbon-type active zone (AZ) and yet SGNs indefatigably spike up to hundreds of Hz to encode acoustic stimuli with submillisecond precision. Accumulating evidence indicates a highly specialized molecular composition and structure of the presynapse, adapted to suit these high functional demands. However, we are only beginning to understand key features such as stimulus-secretion coupling, exocytosis mechanisms, exo-endocytosis coupling, modes of endocytosis and vesicle reformation, as well as replenishment of the readily releasable pool. Relating structure and function has become an important avenue in addressing these points and has been applied to normal and genetically manipulated hair cell synapses. Here, we review some of the exciting new insights gained from recent studies of the molecular anatomy and physiology of IHC ribbon synapses.
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Affiliation(s)
- C. Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University Medical Center Göttingen, Göttingen, Germany
| | - T. Moser
- Collaborative Research Center 889, University Medical Center Göttingen, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany
- Bernstein Center for Computational Neuroscience, University of Göttingen, Göttingen, Germany
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48
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Giniatullina A, Maroteaux G, Geerts CJ, Koopmans B, Loos M, Klaassen R, Chen N, van der Schors RC, van Nierop P, Li KW, de Jong J, Altrock WD, Cornelisse LN, Toonen RF, van der Sluis S, Sullivan PF, Stiedl O, Posthuma D, Smit AB, Groffen AJ, Verhage M. Functional characterization of the PCLO p.Ser4814Ala variant associated with major depressive disorder reveals cellular but not behavioral differences. Neuroscience 2015; 300:518-38. [PMID: 26045179 DOI: 10.1016/j.neuroscience.2015.05.047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 05/17/2015] [Accepted: 05/20/2015] [Indexed: 12/14/2022]
Abstract
Genome-wide association studies have suggested a role for a genetic variation in the presynaptic gene PCLO in major depressive disorder (MDD). As with many complex traits, the PCLO variant has a small contribution to the overall heritability and the association does not always replicate. One variant (rs2522833, p.Ser4814Ala) is of particular interest given that it is a common, nonsynonymous exon variant near a calcium-sensing part of PCLO. It has been suggested that the molecular effects of such variations penetrate to a variable extent in the population due to phenotypic and genotypic heterogeneity at the population level. More robust effects may be exposed by studying such variations in isolation, in a more homogeneous context. We tested this idea by modeling PCLO variation in a mouse knock-in model expressing the Pclo(SA)(/)(SA) variant. In the highly homogeneous background of inbred mice, two functional effects of the SA-variation were observed at the cellular level: increased synaptic Piccolo levels, and 30% increased excitatory synaptic transmission in cultured neurons. Other aspects of Piccolo function were unaltered: calcium-dependent phospholipid binding, synapse formation in vitro, and synaptic accumulation of synaptic vesicles. Moreover, anxiety, cognition and depressive-like behavior were normal in Pclo(SA)(/)(SA) mice. We conclude that the PCLO p.Ser4814Ala missense variant produces mild cellular phenotypes, which do not translate into behavioral phenotypes. We propose a model explaining how (subtle) cellular phenotypes do not penetrate to the mouse behavioral level but, due to genetic and phenotypic heterogeneity and non-linearity, can produce association signals in human population studies.
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Affiliation(s)
- A Giniatullina
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - G Maroteaux
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - C J Geerts
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - B Koopmans
- Sylics (Synaptologics BV), Amsterdam, The Netherlands
| | - M Loos
- Sylics (Synaptologics BV), Amsterdam, The Netherlands
| | - R Klaassen
- Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - N Chen
- Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - R C van der Schors
- Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - P van Nierop
- Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - K W Li
- Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - J de Jong
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - W D Altrock
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - L N Cornelisse
- Department of Clinical Genetics, Section Complex Trait Genetics, VU University Medical Center, Amsterdam, The Netherlands
| | - R F Toonen
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - S van der Sluis
- Department of Clinical Genetics, Section Complex Trait Genetics, VU University Medical Center, Amsterdam, The Netherlands
| | - P F Sullivan
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA; Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - O Stiedl
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands; Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - D Posthuma
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands; Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - A B Smit
- Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - A J Groffen
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - M Verhage
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands; Department of Clinical Genetics, Section Complex Trait Genetics, VU University Medical Center, Amsterdam, The Netherlands.
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49
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Wagh D, Terry-Lorenzo R, Waites CL, Leal-Ortiz SA, Maas C, Reimer RJ, Garner CC. Piccolo Directs Activity Dependent F-Actin Assembly from Presynaptic Active Zones via Daam1. PLoS One 2015; 10:e0120093. [PMID: 25897839 PMCID: PMC4405365 DOI: 10.1371/journal.pone.0120093] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 01/23/2015] [Indexed: 12/12/2022] Open
Abstract
The dynamic assembly of filamentous (F) actin plays essential roles in the assembly of presynaptic boutons, the fusion, mobilization and recycling of synaptic vesicles (SVs), and presynaptic forms of plasticity. However, the molecular mechanisms that regulate the temporal and spatial assembly of presynaptic F-actin remain largely unknown. Similar to other F-actin rich membrane specializations, presynaptic boutons contain a set of molecules that respond to cellular cues and trans-synaptic signals to facilitate activity-dependent assembly of F-actin. The presynaptic active zone (AZ) protein Piccolo has recently been identified as a key regulator of neurotransmitter release during SV cycling. It does so by coordinating the activity-dependent assembly of F-Actin and the dynamics of key plasticity molecules including Synapsin1, Profilin and CaMKII. The multidomain structure of Piccolo, its exquisite association with the AZ, and its ability to interact with a number of actin-associated proteins suggest that Piccolo may function as a platform to coordinate the spatial assembly of F-actin. Here we have identified Daam1, a Formin that functions with Profilin to drive F-actin assembly, as a novel Piccolo binding partner. We also found that within cells Daam1 activation promotes Piccolo binding, an interaction that can spatially direct the polymerization of F-Actin. Moreover, similar to Piccolo and Profilin, Daam1 loss of function impairs presynaptic-F-actin assembly in neurons. These data suggest a model in which Piccolo directs the assembly of presynaptic F-Actin from the AZ by scaffolding key actin regulatory proteins including Daam1.
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Affiliation(s)
- Dhananjay Wagh
- Department of Psychiatry and Behavioral Sciences, Nancy Pritzker Laboratory, Stanford University, Stanford, California, United States of America
| | - Ryan Terry-Lorenzo
- Department of Psychiatry and Behavioral Sciences, Nancy Pritzker Laboratory, Stanford University, Stanford, California, United States of America
| | - Clarissa L. Waites
- Department of Pathology and Cell Biology Columbia University New York, New York, United States of America
| | - Sergio A. Leal-Ortiz
- Department of Psychiatry and Behavioral Sciences, Nancy Pritzker Laboratory, Stanford University, Stanford, California, United States of America
| | - Christoph Maas
- Department of Psychiatry and Behavioral Sciences, Nancy Pritzker Laboratory, Stanford University, Stanford, California, United States of America
| | - Richard J. Reimer
- Department of Neurology and Neurological Sciences Stanford University and Veterans Affairs Palo Alto Health Care System, Palo Alto, California, United States of America
| | - Craig C. Garner
- Department of Psychiatry and Behavioral Sciences, Nancy Pritzker Laboratory, Stanford University, Stanford, California, United States of America
- * E-mail:
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50
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Martín-Flores N, Romaní-Aumedes J, Rué L, Canal M, Sanders P, Straccia M, Allen ND, Alberch J, Canals JM, Pérez-Navarro E, Malagelada C. RTP801 Is Involved in Mutant Huntingtin-Induced Cell Death. Mol Neurobiol 2015; 53:2857-2868. [PMID: 25876513 DOI: 10.1007/s12035-015-9166-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 03/30/2015] [Indexed: 01/16/2023]
Abstract
RTP801 expression is induced by cellular stress and has a pro-apoptotic function in non-proliferating differentiated cells such as neurons. In several neurodegenerative disorders, including Parkinson's disease and Alzheimer's disease, elevated levels of RTP801 have been observed, which suggests a role for RTP801 in neuronal death. Neuronal death is also a pathological hallmark in Huntington's disease (HD), an inherited neurodegenerative disorder caused by a CAG repeat expansion in the huntingtin gene. Currently, the exact mechanisms underlying mutant huntingtin (mhtt)-induced toxicity are still unclear. Here, we investigated whether RTP801 is involved in (mhtt)-induced cell death. Ectopic exon-1 mhtt elevated RTP801 mRNA and protein levels in nerve growth factor (NGF)-differentiated PC12 cells and in rat primary cortical neurons. In neuronal PC12 cells, mhtt also contributed to RTP801 protein elevation by reducing its proteasomal degradation rate, in addition to promoting RTP801 gene expression. Interestingly, silencing RTP801 expression with short hairpin RNAs (shRNAs) blocked mhtt-induced cell death in NGF-differentiated PC12 cells. However, RTP801 protein levels were not altered in the striatum of Hdh(Q7/Q111) and R6/1 mice, two HD models that display motor deficits but not neuronal death. Importantly, RTP801 protein levels were elevated in both neural telencephalic progenitors differentiated from HD patient-derived induced pluripotent stem cells and in the putamen and cerebellum of human HD postmortem brains. Taken together, our results suggest that RTP801 is a novel downstream effector of mhtt-induced toxicity and that it may be relevant to the human disease.
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Affiliation(s)
- Núria Martín-Flores
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain
| | - Joan Romaní-Aumedes
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain
| | - Laura Rué
- Department of Cell Biology, Immunology and Neurosciences, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Mercè Canal
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain
| | - Phil Sanders
- Department of Cell Biology, Immunology and Neurosciences, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Marco Straccia
- Department of Cell Biology, Immunology and Neurosciences, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Nicholas D Allen
- Divisions of Pathophysiology & Repair and Neuroscience, School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK
| | - Jordi Alberch
- Department of Cell Biology, Immunology and Neurosciences, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Josep M Canals
- Department of Cell Biology, Immunology and Neurosciences, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Esther Pérez-Navarro
- Department of Cell Biology, Immunology and Neurosciences, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain. .,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Catalonia, Spain. .,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
| | - Cristina Malagelada
- Department of Pathological Anatomy, Pharmacology and Microbiology, Faculty of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.
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