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Kim YD, Park HG, Song S, Kim J, Lee BJ, Broadie K, Lee S. Presynaptic structural and functional plasticity are coupled by convergent Rap1 signaling. J Cell Biol 2024; 223:e202309095. [PMID: 38748250 PMCID: PMC11096849 DOI: 10.1083/jcb.202309095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 02/07/2024] [Accepted: 03/27/2024] [Indexed: 05/18/2024] Open
Abstract
Dynamic presynaptic actin remodeling drives structural and functional plasticity at synapses, but the underlying mechanisms remain largely unknown. Previous work has shown that actin regulation via Rac1 guanine exchange factor (GEF) Vav signaling restrains synaptic growth via bone morphogenetic protein (BMP)-induced receptor macropinocytosis and mediates synaptic potentiation via mobilization of reserve pool vesicles in presynaptic boutons. Here, we find that Gef26/PDZ-GEF and small GTPase Rap1 signaling couples the BMP-induced activation of Abelson kinase to this Vav-mediated macropinocytosis. Moreover, we find that adenylate cyclase Rutabaga (Rut) signaling via exchange protein activated by cAMP (Epac) drives the mobilization of reserve pool vesicles during post-tetanic potentiation (PTP). We discover that Rap1 couples activation of Rut-cAMP-Epac signaling to Vav-mediated synaptic potentiation. These findings indicate that Rap1 acts as an essential, convergent node for Abelson kinase and cAMP signaling to mediate BMP-induced structural plasticity and activity-induced functional plasticity via Vav-dependent regulation of the presynaptic actin cytoskeleton.
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Affiliation(s)
- Yeongjin David Kim
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Korea
| | - Hyun Gwan Park
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Korea
| | - Seunghwan Song
- Interdisciplinary Program in Neuroscience, Seoul National University, Seoul, Korea
| | - Joohyung Kim
- Department of Cell and Developmental Biology and Dental Research Institute, Seoul National University, Seoul, Korea
| | - Byoung Ju Lee
- Department of Cell and Developmental Biology and Dental Research Institute, Seoul National University, Seoul, Korea
| | - Kendal Broadie
- Departments of Cell and Developmental Biology, Pharmacology, and Biological Sciences, Vanderbilt University and Medical Center, Nashville, TN, USA
| | - Seungbok Lee
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Korea
- Interdisciplinary Program in Neuroscience, Seoul National University, Seoul, Korea
- Department of Cell and Developmental Biology and Dental Research Institute, Seoul National University, Seoul, Korea
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2
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Medeiros AT, Gratz S, Delgado A, Ritt J, O’Connor-Giles KM. Ca 2+ channel and active zone protein abundance intersects with input-specific synapse organization to shape functional synaptic diversity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.04.02.535290. [PMID: 37034654 PMCID: PMC10081318 DOI: 10.1101/2023.04.02.535290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
Abstract
Synaptic heterogeneity is a hallmark of nervous systems that enables complex and adaptable communication in neural circuits. To understand circuit function, it is thus critical to determine the factors that contribute to the functional diversity of synapses. We investigated the contributions of voltage-gated calcium channel (VGCC) abundance, spatial organization, and subunit composition to synapse diversity among and between synapses formed by two closely related Drosophila glutamatergic motor neurons with distinct neurotransmitter release probabilities (Pr). Surprisingly, VGCC levels are highly predictive of heterogeneous Pr among individual synapses of either low- or high-Pr inputs, but not between inputs. We find that the same number of VGCCs are more densely organized at high-Pr synapses, consistent with tighter VGCC-synaptic vesicle coupling. We generated endogenously tagged lines to investigate VGCC subunits in vivo and found that the α2δ-3 subunit Straightjacket along with the CAST/ELKS active zone (AZ) protein Bruchpilot, both key regulators of VGCCs, are less abundant at high-Pr inputs, yet positively correlate with Pr among synapses formed by either input. Consistently, both Straightjacket and Bruchpilot levels are dynamically increased across AZs of both inputs when neurotransmitter release is potentiated to maintain stable communication following glutamate receptor inhibition. Together, these findings suggest a model in which VGCC and AZ protein abundance intersects with input-specific spatial and molecular organization to shape the functional diversity of synapses.
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Affiliation(s)
- A. T. Medeiros
- Neuroscience Graduate Training Program, Brown University, Providence, RI
| | - S.J. Gratz
- Department of Neuroscience, Brown University, Providence, RI
| | - A. Delgado
- Department of Neuroscience, Brown University, Providence, RI
| | - J.T. Ritt
- Department of Neuroscience, Brown University, Providence, RI
- Carney Institute for Brain Science, Brown University, Providence, RI
| | - Kate M. O’Connor-Giles
- Neuroscience Graduate Training Program, Brown University, Providence, RI
- Department of Neuroscience, Brown University, Providence, RI
- Carney Institute for Brain Science, Brown University, Providence, RI
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3
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Nguyen TH, Vicidomini R, Choudhury SD, Han TH, Maric D, Brody T, Serpe M. scRNA-seq data from the larval Drosophila ventral cord provides a resource for studying motor systems function and development. Dev Cell 2024; 59:1210-1230.e9. [PMID: 38569548 PMCID: PMC11078614 DOI: 10.1016/j.devcel.2024.03.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 12/05/2023] [Accepted: 03/06/2024] [Indexed: 04/05/2024]
Abstract
The Drosophila larval ventral nerve cord (VNC) shares many similarities with the spinal cord of vertebrates and has emerged as a major model for understanding the development and function of motor systems. Here, we use high-quality scRNA-seq, validated by anatomical identification, to create a comprehensive census of larval VNC cell types. We show that the neural lineages that comprise the adult VNC are already defined, but quiescent, at the larval stage. Using fluorescence-activated cell sorting (FACS)-enriched populations, we separate all motor neuron bundles and link individual neuron clusters to morphologically characterized known subtypes. We discovered a glutamate receptor subunit required for basal neurotransmission and homeostasis at the larval neuromuscular junction. We describe larval glia and endorse the general view that glia perform consistent activities throughout development. This census represents an extensive resource and a powerful platform for future discoveries of cellular and molecular mechanisms in repair, regeneration, plasticity, homeostasis, and behavioral coordination.
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Affiliation(s)
| | | | | | | | - Dragan Maric
- Flow and Imaging Cytometry Core, NINDS, NIH, Bethesda, MD 20892, USA
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4
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Wise DL, Greene SB, Escobedo-Lozoya Y, Van Hooser SD, Nelson SB. Progressive Circuit Hyperexcitability in Mouse Neocortical Slice Cultures with Increasing Duration of Activity Silencing. eNeuro 2024; 11:ENEURO.0362-23.2024. [PMID: 38653560 PMCID: PMC11079856 DOI: 10.1523/eneuro.0362-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 04/09/2024] [Accepted: 04/12/2024] [Indexed: 04/25/2024] Open
Abstract
Forebrain neurons deprived of activity become hyperactive when activity is restored. Rebound activity has been linked to spontaneous seizures in vivo following prolonged activity blockade. Here, we measured the time course of rebound activity and the contributing circuit mechanisms using calcium imaging, synaptic staining, and whole-cell patch clamp in organotypic slice cultures of mouse neocortex. Calcium imaging revealed hypersynchronous activity increasing in intensity with longer periods of deprivation. While activity partially recovered 3 d after slices were released from 5 d of deprivation, they were less able to recover after 10 d of deprivation. However, even after the longer period of deprivation, activity patterns eventually returned to baseline levels. The degree of deprivation-induced rebound was age-dependent, with the greatest effects occurring when silencing began in the second week. Pharmacological blockade of NMDA receptors indicated that hypersynchronous rebound activity did not require activation of Hebbian plasticity. In single-neuron recordings, input resistance roughly doubled with a concomitant increase in intrinsic excitability. Synaptic imaging of pre- and postsynaptic proteins revealed dramatic reductions in the number of presumptive synapses with a larger effect on inhibitory than excitatory synapses. Putative excitatory synapses colocalizing PSD-95 and Bassoon declined by 39 and 56% following 5 and 10 d of deprivation, but presumptive inhibitory synapses colocalizing gephyrin and VGAT declined by 55 and 73%, respectively. The results suggest that with prolonged deprivation, a progressive reduction in synapse number is accompanied by a shift in the balance between excitation and inhibition and increased cellular excitability.
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Affiliation(s)
- Derek L Wise
- Department of Biology, Brandeis University, Waltham, Massachusetts 02454
| | - Samuel B Greene
- Department of Biology, Brandeis University, Waltham, Massachusetts 02454
| | | | | | - Sacha B Nelson
- Department of Biology, Brandeis University, Waltham, Massachusetts 02454
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5
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Godavarthi SK, Hiramoto M, Ignatyev Y, Levin JB, Li HQ, Pratelli M, Borchardt J, Czajkowski C, Borodinsky LN, Sweeney L, Cline HT, Spitzer NC. Postsynaptic receptors regulate presynaptic transmitter stability through transsynaptic bridges. Proc Natl Acad Sci U S A 2024; 121:e2318041121. [PMID: 38568976 PMCID: PMC11009644 DOI: 10.1073/pnas.2318041121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 02/27/2024] [Indexed: 04/05/2024] Open
Abstract
Stable matching of neurotransmitters with their receptors is fundamental to synapse function and reliable communication in neural circuits. Presynaptic neurotransmitters regulate the stabilization of postsynaptic transmitter receptors. Whether postsynaptic receptors regulate stabilization of presynaptic transmitters has received less attention. Here, we show that blockade of endogenous postsynaptic acetylcholine receptors (AChR) at the neuromuscular junction destabilizes the cholinergic phenotype in motor neurons and stabilizes an earlier, developmentally transient glutamatergic phenotype. Further, expression of exogenous postsynaptic gamma-aminobutyric acid type A receptors (GABAA receptors) in muscle cells stabilizes an earlier, developmentally transient GABAergic motor neuron phenotype. Both AChR and GABAA receptors are linked to presynaptic neurons through transsynaptic bridges. Knockdown of specific components of these transsynaptic bridges prevents stabilization of the cholinergic or GABAergic phenotypes. Bidirectional communication can enforce a match between transmitter and receptor and ensure the fidelity of synaptic transmission. Our findings suggest a potential role of dysfunctional transmitter receptors in neurological disorders that involve the loss of the presynaptic transmitter.
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Affiliation(s)
- Swetha K. Godavarthi
- Neurobiology Department, University of California San Diego, La Jolla, CA92093
- Kavli Institute for Brain & Mind, University of California San Diego, La Jolla, CA92093
| | - Masaki Hiramoto
- Neuroscience Department, The Scripps Research Institute, La Jolla, CA92037
| | - Yuri Ignatyev
- Institute of Science and Technology Austria, Klosterneuburg3400, Austria
| | - Jacqueline B. Levin
- Department of Physiology & Membrane Biology Shriners Hospital for Children Northern California, University of California Davis School of Medicine, Sacramento, CA95817
| | - Hui-quan Li
- Neurobiology Department, University of California San Diego, La Jolla, CA92093
- Kavli Institute for Brain & Mind, University of California San Diego, La Jolla, CA92093
| | - Marta Pratelli
- Neurobiology Department, University of California San Diego, La Jolla, CA92093
- Kavli Institute for Brain & Mind, University of California San Diego, La Jolla, CA92093
| | - Jennifer Borchardt
- Neuroscience Department, University of Wisconsin Madison, Madison, WI53705
| | - Cynthia Czajkowski
- Neuroscience Department, University of Wisconsin Madison, Madison, WI53705
| | - Laura N. Borodinsky
- Department of Physiology & Membrane Biology Shriners Hospital for Children Northern California, University of California Davis School of Medicine, Sacramento, CA95817
| | - Lora Sweeney
- Institute of Science and Technology Austria, Klosterneuburg3400, Austria
| | - Hollis T. Cline
- Neuroscience Department, The Scripps Research Institute, La Jolla, CA92037
| | - Nicholas C. Spitzer
- Neurobiology Department, University of California San Diego, La Jolla, CA92093
- Kavli Institute for Brain & Mind, University of California San Diego, La Jolla, CA92093
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6
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Beckers CJ, Mrestani A, Komma F, Dannhäuser S. Versatile Endogenous Editing of GluRIIA in Drosophila melanogaster. Cells 2024; 13:323. [PMID: 38391936 PMCID: PMC10887371 DOI: 10.3390/cells13040323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 02/05/2024] [Accepted: 02/08/2024] [Indexed: 02/24/2024] Open
Abstract
Glutamate receptors at the postsynaptic side translate neurotransmitter release from presynapses into postsynaptic excitation. They play a role in many forms of synaptic plasticity, e.g., homeostatic scaling of the receptor field, activity-dependent synaptic plasticity and the induction of presynaptic homeostatic potentiation (PHP). The latter process has been extensively studied at Drosophila melanogaster neuromuscular junctions (NMJs). The genetic removal of the glutamate receptor subunit IIA (GluRIIA) leads to an induction of PHP at the synapse. So far, mostly imprecise knockouts of the GluRIIA gene have been utilized. Furthermore, mutated and tagged versions of GluRIIA have been examined in the past, but most of these constructs were not expressed under endogenous regulatory control or involved the mentioned imprecise GluRIIA knockouts. We performed CRISPR/Cas9-assisted gene editing at the endogenous locus of GluRIIA. This enabled the investigation of the endogenous expression pattern of GluRIIA using tagged constructs with an EGFP and an ALFA tag for super-resolution immunofluorescence imaging, including structured illumination microscopy (SIM) and direct stochastic optical reconstruction microscopy (dSTORM). All GluRIIA constructs exhibited full functionality and PHP could be induced by philanthotoxin at control levels. By applying hierarchical clustering algorithms to analyze the dSTORM data, we detected postsynaptic receptor cluster areas of ~0.15 µm2. Consequently, our constructs are suitable for ultrastructural analyses of GluRIIA.
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Affiliation(s)
- Constantin J. Beckers
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, D-97070 Würzburg, Germany
| | - Achmed Mrestani
- Department of Neurology, University of Leipzig Medical Center, D-04103 Leipzig, Germany;
- Rudolf Schönheimer Institute of Biochemistry, Division of General Biochemistry, Medical Faculty, Leipzig University, D-04103 Leipzig, Germany
| | - Fabian Komma
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, D-97070 Würzburg, Germany
| | - Sven Dannhäuser
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, D-97070 Würzburg, Germany
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7
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Mori M, Rosko A, Farnsworth J, Carrasco G, Broomandkhoshbacht P, Pareja-Navarro K, Pejmun Haghighi A. SimplyFire: An Open-Source, Customizable Software Application for the Analysis of Synaptic Events. eNeuro 2024; 11:ENEURO.0326-23.2023. [PMID: 38167616 PMCID: PMC10849045 DOI: 10.1523/eneuro.0326-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 11/30/2023] [Accepted: 12/21/2023] [Indexed: 01/05/2024] Open
Abstract
We have developed an open-source software for neuroscientists to analyze electrophysiological recordings. Named SimplyFire, the software gives the users the flexibility to analyze a variety of recordings using an interactive graphical user interface or as an importable Python package. The software features a simple plugin structure that allows users to create and deploy various electrophysiology analysis tools. SimplyFire is pre-packaged with tools commonly used in electrophysiology, such as noise filtering, trace averaging, miniature analysis, and trace exporting. We discuss in detail the algorithm behind the different features of the analysis tool. We verify the accuracy of the algorithm by testing the software using computer-generated traces with known true values of the events. SimplyFire will be distributed under the GPLv3.0 license. The open nature of this software will allow interested investigators to modify and expand the software for additional capabilities as needed. We believe this software will not only compete with commercially available software packages but will also present a powerful tool to meet the current and unmet needs of electrophysiologists.
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Affiliation(s)
- Megumi Mori
- The Buck Institute for Research on Aging, Novato 94947, California
- Gladstone Institute of Neurological Disease, Gladstone Institutes, San Francisco 94158, California
| | - Andrew Rosko
- The Buck Institute for Research on Aging, Novato 94947, California
| | - Jill Farnsworth
- The Buck Institute for Research on Aging, Novato 94947, California
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8
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Mrestani A, Dannhäuser S, Pauli M, Kollmannsberger P, Hübsch M, Morris L, Langenhan T, Heckmann M, Paul MM. Nanoscaled RIM clustering at presynaptic active zones revealed by endogenous tagging. Life Sci Alliance 2023; 6:e202302021. [PMID: 37696575 PMCID: PMC10494931 DOI: 10.26508/lsa.202302021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 08/27/2023] [Accepted: 08/28/2023] [Indexed: 09/13/2023] Open
Abstract
Chemical synaptic transmission involves neurotransmitter release from presynaptic active zones (AZs). The AZ protein Rab-3-interacting molecule (RIM) is important for normal Ca2+-triggered release. However, its precise localization within AZs of the glutamatergic neuromuscular junctions of Drosophila melanogaster remains elusive. We used CRISPR/Cas9-assisted genome engineering of the rim locus to incorporate small epitope tags for targeted super-resolution imaging. A V5-tag, derived from simian virus 5, and an HA-tag, derived from human influenza virus, were N-terminally fused to the RIM Zinc finger. Whereas both variants are expressed in co-localization with the core AZ scaffold Bruchpilot, electrophysiological characterization reveals that AP-evoked synaptic release is disturbed in rimV5-Znf but not in rimHA-Znf In addition, rimHA-Znf synapses show intact presynaptic homeostatic potentiation. Combining super-resolution localization microscopy and hierarchical clustering, we detect ∼10 RIMHA-Znf subclusters with ∼13 nm diameter per AZ that are compacted and increased in numbers in presynaptic homeostatic potentiation.
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Affiliation(s)
- Achmed Mrestani
- https://ror.org/00fbnyb24 Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
- Department of Neurology, Leipzig University Medical Center, Leipzig, Germany
- Division of General Biochemistry, Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Sven Dannhäuser
- https://ror.org/00fbnyb24 Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Martin Pauli
- https://ror.org/00fbnyb24 Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | | | - Martha Hübsch
- https://ror.org/00fbnyb24 Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Lydia Morris
- Division of General Biochemistry, Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Tobias Langenhan
- Division of General Biochemistry, Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Manfred Heckmann
- https://ror.org/00fbnyb24 Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Mila M Paul
- https://ror.org/00fbnyb24 Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
- https://ror.org/03pvr2g57 Department of Orthopedic Trauma, Hand, Plastic and Reconstructive Surgery, University Hospital of Würzburg, Würzburg, Germany
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9
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Zhang Y, Wang T, Cai Y, Cui T, Kuah M, Vicini S, Wang T. Role of α2δ-3 in regulating calcium channel localization at presynaptic active zones during homeostatic plasticity. Front Mol Neurosci 2023; 16:1253669. [PMID: 38025261 PMCID: PMC10662314 DOI: 10.3389/fnmol.2023.1253669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
The homeostatic modulation of synaptic transmission is an evolutionarily conserved mechanism that is critical for stabilizing the nervous system. At the Drosophila neuromuscular junction (NMJ), presynaptic homeostatic potentiation (PHP) compensates for impairments in postsynaptic glutamate receptors due to pharmacological blockade or genetic deletion. During PHP, there is an increase in presynaptic neurotransmitter release, counteracting postsynaptic changes and restoring excitation to baseline levels. Previous studies have shown that α2δ-3, an auxiliary subunit of voltage-gated calcium channels (VGCCs), is essential for both the rapid induction and sustained expression of PHP at the Drosophila NMJ. However, the molecular mechanisms by which α2δ-3 regulates neurotransmitter release during PHP remain to be elucidated. In this study, we utilized electrophysiological, confocal imaging, and super-resolution imaging approaches to explore how α2δ-3 regulates synaptic transmission during PHP. Our findings suggest that α2δ-3 governs PHP by controlling the localization of the calcium channel pore-forming α1 subunit at presynaptic release sites, or active zones. Moreover, we examined the role of two structural domains within α2δ-3 in regulating neurotransmitter release and calcium channel localization. Our results highlight that these domains in α2δ-3 serve distinct functions in controlling synaptic transmission and presynaptic calcium channel abundance, at baseline in the absence of perturbations and during PHP. In summary, our research offers compelling evidence that α2δ-3 is an indispensable signaling component for controlling calcium channel trafficking and stabilization in homeostatic plasticity.
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Affiliation(s)
- Yanfeng Zhang
- Department of Pediatric Neurology, First Hospital of Jilin University, Changchun, Jilin, China
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
| | - Ting Wang
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
| | - Yimei Cai
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
| | - Tao Cui
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
| | - Michelle Kuah
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
| | - Stefano Vicini
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
- Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, DC, United States
| | - Tingting Wang
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
- Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, DC, United States
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10
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Cai Y, Cui T, Yin P, Paganelli P, Vicini S, Wang T. Dysregulated glial genes in Alzheimer's disease are essential for homeostatic plasticity: Evidence from integrative epigenetic and single cell analyses. Aging Cell 2023; 22:e13989. [PMID: 37712202 PMCID: PMC10652298 DOI: 10.1111/acel.13989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 08/18/2023] [Accepted: 08/30/2023] [Indexed: 09/16/2023] Open
Abstract
Synaptic homeostatic plasticity is a foundational regulatory mechanism that maintains the stability of synaptic and neural functions within the nervous system. Impairment of homeostatic regulation has been linked to synapse destabilization during the progression of Alzheimer's disease (AD). Recent epigenetic and transcriptomic characterizations of the nervous system have revealed intricate molecular details about the aging brain and the pathogenesis of neurodegenerative diseases. Yet, how abnormal epigenetic and transcriptomic alterations in different cell types in AD affect synaptic homeostatic plasticity remains to be elucidated. Various glial cell types play critical roles in modulating synaptic functions both during the aging process and in the context of AD. Here, we investigated the impact of glial dysregulation of histone acetylation and transcriptome in AD on synaptic homeostatic plasticity, using computational analysis combined with electrophysiological methods in Drosophila. By integrating snRNA-seq and H3K9ac ChIP-seq data from the same AD patient cohort, we pinpointed cell type-specific signature genes that were transcriptionally altered by histone acetylation. We subsequently investigated the role of these glial genes in regulating presynaptic homeostatic potentiation in Drosophila. Remarkably, nine glial-specific genes, which were identified through our computational method as targets of H3K9ac and transcriptional dysregulation, were found to be crucial for the regulation of synaptic homeostatic plasticity in Drosophila. Our genetic evidence connects abnormal glial transcriptomic changes in AD with the impairment of homeostatic plasticity in the nervous system. In summary, our integrative computational and genetic studies highlight specific glial genes as potential key players in the homeostatic imbalance observed in AD.
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Affiliation(s)
- Yimei Cai
- Department of Pharmacology & PhysiologyGeorgetown University Medical CenterWashingtonD.C.USA
| | - Tao Cui
- Department of Pharmacology & PhysiologyGeorgetown University Medical CenterWashingtonD.C.USA
- Interdisciplinary Program in NeuroscienceGeorgetown University Medical CenterWashingtonD.C.USA
| | - Pengqi Yin
- Department of Pharmacology & PhysiologyGeorgetown University Medical CenterWashingtonD.C.USA
- Present address:
Department of Neurology, Shanghai General HospitalShanghai Jiao Tong University School of MedicineShanghaiChina
- Present address:
Department of Neurology, First Affiliated HospitalHarbin Medical UniversityHarbinChina
| | - Paxton Paganelli
- Department of Pharmacology & PhysiologyGeorgetown University Medical CenterWashingtonD.C.USA
| | - Stefano Vicini
- Department of Pharmacology & PhysiologyGeorgetown University Medical CenterWashingtonD.C.USA
- Interdisciplinary Program in NeuroscienceGeorgetown University Medical CenterWashingtonD.C.USA
| | - Tingting Wang
- Department of Pharmacology & PhysiologyGeorgetown University Medical CenterWashingtonD.C.USA
- Interdisciplinary Program in NeuroscienceGeorgetown University Medical CenterWashingtonD.C.USA
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11
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Yin P, Cai Y, Cui T, Berg AJ, Wang T, Morency DT, Paganelli PM, Lok C, Xue Y, Vicini S, Wang T. Glial Sphingosine-Mediated Epigenetic Regulation Stabilizes Synaptic Function in Drosophila Models of Alzheimer's Disease. J Neurosci 2023; 43:6954-6971. [PMID: 37669862 PMCID: PMC10586542 DOI: 10.1523/jneurosci.0515-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 07/25/2023] [Accepted: 08/10/2023] [Indexed: 09/07/2023] Open
Abstract
Destabilization of neural activity caused by failures of homeostatic regulation has been hypothesized to drive the progression of Alzheimer's Disease (AD). However, the underpinning mechanisms that connect synaptic homeostasis and the disease etiology are yet to be fully understood. Here, we demonstrated that neuronal overexpression of amyloid β (Aβ) causes abnormal histone acetylation in peripheral glia and completely blocks presynaptic homeostatic potentiation (PHP) at the neuromuscular junction in Drosophila The synaptic deficits caused by Aβ overexpression in motoneurons are associated with motor function impairment at the adult stage. Moreover, we found that a sphingosine analog drug, Fingolimod, ameliorates synaptic homeostatic plasticity impairment, abnormal glial histone acetylation, and motor behavior defects in the Aβ models. We further demonstrated that perineurial glial sphingosine kinase 2 (Sk2) is not only required for PHP, but also plays a beneficial role in modulating PHP in the Aβ models. Glial overexpression of Sk2 rescues PHP, glial histone acetylation, and motor function deficits that are associated with Aβ in Drosophila Finally, we showed that glial overexpression of Sk2 restores PHP and glial histone acetylation in a genetic loss-of-function mutant of the Spt-Ada-Gcn5 Acetyltransferase complex, strongly suggesting that Sk2 modulates PHP through epigenetic regulation. Both male and female animals were used in the experiments and analyses in this study. Collectively, we provided genetic evidence demonstrating that abnormal glial epigenetic alterations in Aβ models in Drosophila are associated with the impairment of PHP and that the sphingosine signaling pathway displays protective activities in stabilizing synaptic physiology.SIGNIFICANCE STATEMENT Fingolimod, an oral drug to treat multiple sclerosis, is phosphorylated by sphingosine kinases to generate its active form. It is known that Fingolimod enhances the cognitive function in mouse models of Alzheimer's disease (AD), but the role of sphingosine kinases in AD is not clear. We bridge this knowledge gap by demonstrating the relationship between impaired homeostatic plasticity and AD. We show that sphingosine kinase 2 (Sk2) in glial cells is necessary for homeostatic plasticity and that glial Sk2-mediated epigenetic signaling has a protective role in synapse stabilization. Our findings demonstrate the potential of the glial sphingosine signaling as a key player in glia-neuron interactions during homeostatic plasticity, suggesting it could be a promising target for sustaining synaptic function in AD.
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Affiliation(s)
- Pengqi Yin
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington, DC 20007
- Department of Neurology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
- Department of Neurology, First Affiliated Hospital, Harbin Medical University, Harbin 150081, China
| | - Yimei Cai
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington, DC 20007
| | - Tao Cui
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington, DC 20007
| | - Andrew J Berg
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington, DC 20007
| | - Ting Wang
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington, DC 20007
| | - Danielle T Morency
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington, DC 20007
- Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, DC 20007
| | - Paxton M Paganelli
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington, DC 20007
| | - Chloe Lok
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington, DC 20007
- Department of Biology, Georgetown University, Washington, DC 20007
| | - Yang Xue
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington, DC 20007
- Department of Neurology, First Affiliated Hospital, Harbin Medical University, Harbin 150081, China
| | - Stefano Vicini
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington, DC 20007
- Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, DC 20007
| | - Tingting Wang
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington, DC 20007
- Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, DC 20007
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12
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Ramesh N, Escher M, Turrel O, Lützkendorf J, Matkovic T, Liu F, Sigrist SJ. An antagonism between Spinophilin and Syd-1 operates upstream of memory-promoting presynaptic long-term plasticity. eLife 2023; 12:e86084. [PMID: 37767892 PMCID: PMC10588984 DOI: 10.7554/elife.86084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023] Open
Abstract
We still face fundamental gaps in understanding how molecular plastic changes of synapses intersect with circuit operation to define behavioral states. Here, we show that an antagonism between two conserved regulatory proteins, Spinophilin (Spn) and Syd-1, controls presynaptic long-term plasticity and the maintenance of olfactory memories in Drosophila. While Spn mutants could not trigger nanoscopic active zone remodeling under homeostatic challenge and failed to stably potentiate neurotransmitter release, concomitant reduction of Syd-1 rescued all these deficits. The Spn/Syd-1 antagonism converged on active zone close F-actin, and genetic or acute pharmacological depolymerization of F-actin rescued the Spn deficits by allowing access to synaptic vesicle release sites. Within the intrinsic mushroom body neurons, the Spn/Syd-1 antagonism specifically controlled olfactory memory stabilization but not initial learning. Thus, this evolutionarily conserved protein complex controls behaviorally relevant presynaptic long-term plasticity, also observed in the mammalian brain but still enigmatic concerning its molecular mechanisms and behavioral relevance.
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Affiliation(s)
- Niraja Ramesh
- Institute for Biology/Genetics, Freie Universität BerlinBerlinGermany
| | - Marc Escher
- Institute for Biology/Genetics, Freie Universität BerlinBerlinGermany
| | - Oriane Turrel
- Institute for Biology/Genetics, Freie Universität BerlinBerlinGermany
| | | | - Tanja Matkovic
- Institute for Biology/Genetics, Freie Universität BerlinBerlinGermany
| | - Fan Liu
- Leibniz-Forschungsinstitut für Molekulare PharmakologieBerlinGermany
| | - Stephan J Sigrist
- Institute for Biology/Genetics, Freie Universität BerlinBerlinGermany
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13
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Machamer JB, Vazquez-Cintron EJ, Stenslik MJ, Pagarigan KT, Bradford AB, Ondeck CA, McNutt PM. Neuromuscular recovery from botulism involves multiple forms of compensatory plasticity. Front Cell Neurosci 2023; 17:1226194. [PMID: 37650071 PMCID: PMC10463753 DOI: 10.3389/fncel.2023.1226194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 07/28/2023] [Indexed: 09/01/2023] Open
Abstract
Introduction Botulinum neurotoxin (BoNT) causes neuroparalytic disease and death by blocking neuromuscular transmission. There are no specific therapies for clinical botulism and the only treatment option is supportive care until neuromuscular function spontaneously recovers, which can take weeks or months after exposure. The highly specialized neuromuscular junction (NMJ) between phrenic motor neurons and diaphragm muscle fibers is the main clinical target of BoNT. Due to the difficulty in eliciting respiratory paralysis without a high mortality rate, few studies have characterized the neurophysiological mechanisms involved in diaphragm recovery from intoxication. Here, we develop a mouse model of botulism that involves partial paralysis of respiratory muscles with low mortality rates, allowing for longitudinal analysis of recovery. Methods and results Mice challenged by systemic administration of 0.7 LD50 BoNT/A developed physiological signs of botulism, such as respiratory depression and reduced voluntary running activity, that persisted for an average of 8-12 d. Studies in isolated hemidiaphragm preparations from intoxicated mice revealed profound reductions in nerve-elicited, tetanic and twitch muscle contraction strengths that recovered to baseline 21 d after intoxication. Despite apparent functional recovery, neurophysiological parameters remained depressed for 28 d, including end plate potential (EPP) amplitude, EPP success rate, quantal content (QC), and miniature EPP (mEPP) frequency. However, QC recovered more quickly than mEPP frequency, which could explain the discrepancy between muscle function studies and neurophysiological recordings. Hypothesizing that differential modulation of voltage-gated calcium channels (VGCC) contributed to the uncoupling of QC from mEPP frequency, pharmacological inhibition studies were used to study the contributions of different VGCCs to neurophysiological function. We found that N-type VGCC and P/Q-type VGCC partially restored QC but not mEPP frequency during recovery from paralysis, potentially explaining the accelerated recovery of evoked release versus spontaneous release. We identified additional changes that presumably compensate for reduced acetylcholine release during recovery, including increased depolarization of muscle fiber resting membrane potential and increased quantal size. Discussion In addition to identifying multiple forms of compensatory plasticity that occur in response to reduced NMJ function, it is expected that insights into the molecular mechanisms involved in recovery from neuromuscular paralysis will support new host-targeted treatments for multiple neuromuscular diseases.
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Affiliation(s)
- James B. Machamer
- BASF, Research Triangle Park, NC, United States
- United States Army Medical Research Institute of Chemical Defense, Gunpowder, MD, United States
| | | | - Mallory J. Stenslik
- United States Army Medical Research Institute of Chemical Defense, Gunpowder, MD, United States
| | - Kathleen T. Pagarigan
- United States Army Medical Research Institute of Chemical Defense, Gunpowder, MD, United States
| | - Aaron B. Bradford
- United States Army Medical Research Institute of Chemical Defense, Gunpowder, MD, United States
| | - Celinia A. Ondeck
- United States Army Medical Research Institute of Chemical Defense, Gunpowder, MD, United States
- Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, United States
| | - Patrick M. McNutt
- United States Army Medical Research Institute of Chemical Defense, Gunpowder, MD, United States
- Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, United States
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14
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Jusyte M, Blaum N, Böhme MA, Berns MMM, Bonard AE, Vámosi ÁB, Pushpalatha KV, Kobbersmed JRL, Walter AM. Unc13A dynamically stabilizes vesicle priming at synaptic release sites for short-term facilitation and homeostatic potentiation. Cell Rep 2023; 42:112541. [PMID: 37243591 DOI: 10.1016/j.celrep.2023.112541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 03/10/2023] [Accepted: 05/03/2023] [Indexed: 05/29/2023] Open
Abstract
Presynaptic plasticity adjusts neurotransmitter (NT) liberation. Short-term facilitation (STF) tunes synapses to millisecond repetitive activation, while presynaptic homeostatic potentiation (PHP) of NT release stabilizes transmission over minutes. Despite different timescales of STF and PHP, our analysis of Drosophila neuromuscular junctions reveals functional overlap and shared molecular dependence on the release-site protein Unc13A. Mutating Unc13A's calmodulin binding domain (CaM-domain) increases baseline transmission while blocking STF and PHP. Mathematical modeling suggests that Ca2+/calmodulin/Unc13A interaction plastically stabilizes vesicle priming at release sites and that CaM-domain mutation causes constitutive stabilization, thereby blocking plasticity. Labeling the functionally essential Unc13A MUN domain reveals higher STED microscopy signals closer to release sites following CaM-domain mutation. Acute phorbol ester treatment similarly enhances NT release and blocks STF/PHP in synapses expressing wild-type Unc13A, while CaM-domain mutation occludes this, indicating common downstream effects. Thus, Unc13A regulatory domains integrate signals across timescales to switch release-site participation for synaptic plasticity.
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Affiliation(s)
- Meida Jusyte
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany; Einstein Center for Neurosciences Berlin, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Natalie Blaum
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Mathias A Böhme
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany; Rudolf Schönheimer Institute of Biochemistry, Division of General Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Manon M M Berns
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Alix E Bonard
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Ábel B Vámosi
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | | | - Janus R L Kobbersmed
- Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark; Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Alexander M Walter
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany; Einstein Center for Neurosciences Berlin, Charité Universitätsmedizin Berlin, Berlin, Germany; Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.
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15
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Mallik B, Brusich DJ, Heyrman G, Frank CA. Precise mapping of one classic and three novel GluRIIA mutants in Drosophila melanogaster. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.000784. [PMID: 37334199 PMCID: PMC10276266 DOI: 10.17912/micropub.biology.000784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 04/24/2023] [Accepted: 05/25/2023] [Indexed: 06/20/2023]
Abstract
Mutation of the Drosophila melanogaster GluRIIA gene or pharmacological agents targeting it are commonly used to assess homeostatic synaptic function at the larval neuromuscular junction (NMJ). The commonly used mutation, GluRIIA SP16 , is a null allele created by a large and imprecise excision of a P-element which affects GluRIIA and multiple upstream genes. Here we mapped the exact bounds of the GluRIIA SP16 allele, refined a multiplex PCR strategy for positive identification of GluRIIA SP16 in homozygous or heterozygous backgrounds, and sequenced and characterized three new CRISPR-generated GluRIIA mutants. We found the three new GluRIIA alleles are apparent nulls that lack GluRIIA immunofluorescence signal at the 3 rd instar larval NMJ and are predicted to cause premature truncations at the genetic level. Further, these new mutants have similar electrophysiological outcomes as GluRIIA SP16 , including reduced miniature excitatory postsynaptic potential (mEPSP) amplitude and frequency compared to controls, and they express robust homeostatic compensation as evidenced by normal excitatory postsynaptic potential (EPSP) amplitude and elevated quantal content. These findings and new tools extend the capacity of the D. melanogaster NMJ for assessment of synaptic function.
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Affiliation(s)
- Bhagaban Mallik
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, Iowa, United States
| | - Douglas J Brusich
- Human Biology Department, University of Wisconsin–Green Bay, Green Bay, Wisconsin, United States
| | - Georgette Heyrman
- Human Biology Department, University of Wisconsin–Green Bay, Green Bay, Wisconsin, United States
| | - C. Andrew Frank
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, Iowa, United States
- Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States
- Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, United States
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16
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Mackay JP, Smith-Dijak AI, Koch ET, Zhang P, Fung E, Nassrallah WB, Buren C, Schmidt M, Hayden MR, Raymond LA. Axonal ER Ca 2+ Release Selectively Enhances Activity-Independent Glutamate Release in a Huntington Disease Model. J Neurosci 2023; 43:3743-3763. [PMID: 36944490 PMCID: PMC10198457 DOI: 10.1523/jneurosci.1593-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 03/08/2023] [Accepted: 03/15/2023] [Indexed: 03/23/2023] Open
Abstract
Action potential (AP)-independent (miniature) neurotransmission occurs at all chemical synapses but remains poorly understood, particularly in pathologic contexts. Axonal endoplasmic reticulum (ER) Ca2+ stores are thought to influence miniature neurotransmission, and aberrant ER Ca2+ handling is implicated in progression of Huntington disease (HD). Here, we report elevated mEPSC frequencies in recordings from YAC128 mouse (HD-model) neurons (from cortical cultures and striatum-containing brain slices, both from male and female animals). Pharmacological experiments suggest that this is mediated indirectly by enhanced tonic ER Ca2+ release. Calcium imaging, using an axon-localized sensor, revealed slow AP-independent ER Ca2+ release waves in both YAC128 and WT cultures. These Ca2+ waves occurred at similar frequencies in both genotypes but spread less extensively and were of lower amplitude in YAC128 axons, consistent with axonal ER Ca2+ store depletion. Surprisingly, basal cytosolic Ca2+ levels were lower in YAC128 boutons and YAC128 mEPSCs were less sensitive to intracellular Ca2+ chelation. Together, these data suggest that elevated miniature glutamate release in YAC128 cultures is associated with axonal ER Ca2+ depletion but not directly mediated by ER Ca2+ release into the cytoplasm. In contrast to increased mEPSC frequencies, cultured YAC128 cortical neurons showed less frequent AP-dependent (spontaneous) Ca2+ events in soma and axons, although evoked glutamate release detected by an intensity-based glutamate-sensing fluorescence reporter in brain slices was similar between genotypes. Our results indicate that axonal ER dysfunction selectively elevates miniature glutamate release from cortical terminals in HD. This, together with reduced spontaneous cortical neuron firing, may cause a shift from activity-dependent to -independent glutamate release in HD, with potential implications for fidelity and plasticity of cortical excitatory signaling.SIGNIFICANCE STATEMENT Miniature neurotransmitter release persists at all chemical neuronal synapses in the absence of action potential firing but remains poorly understood, particularly in disease states. We show enhanced miniature glutamate release from cortical neurons in the YAC128 mouse Huntington disease model. This effect is mediated by axonal ER Ca2+ store depletion, but is not obviously due to elevated ER-to-cytosol Ca2+ release. Conversely, YAC128 cortical pyramidal neurons fired fewer action potentials and evoked cortical glutamate release was similar between WT an YAC128 preparations, indicating axonal ER depletion selectively enhances miniature glutamate release in YAC128 mice. These results extend our understanding of action potential independent neurotransmission and highlight a potential involvement of elevated miniature glutamate release in Huntington disease pathology.
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Affiliation(s)
- James P Mackay
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health
| | - Amy I Smith-Dijak
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health
- Graduate Program in Neuroscience
| | - Ellen T Koch
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health
- Graduate Program in Neuroscience
| | - Peng Zhang
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Evan Fung
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health
| | - Wissam B Nassrallah
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health
- MD/PhD Program
| | - Caodu Buren
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health
- Graduate Program in Neuroscience
| | - Mandi Schmidt
- Graduate Program in Neuroscience
- Centre for Molecular Medicine and Therapeutics, British Columbia Children's Hospital Research Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Michael R Hayden
- Centre for Molecular Medicine and Therapeutics, British Columbia Children's Hospital Research Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Lynn A Raymond
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health
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17
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Geng J, Khaket TP, Pan J, Li W, Zhang Y, Ping Y, Cobos Sillero MI, Lu B. Deregulation of ER-mitochondria contact formation and mitochondrial calcium homeostasis mediated by VDAC in fragile X syndrome. Dev Cell 2023; 58:597-615.e10. [PMID: 37040696 PMCID: PMC10113018 DOI: 10.1016/j.devcel.2023.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 07/31/2022] [Accepted: 03/06/2023] [Indexed: 04/13/2023]
Abstract
Loss of fragile X messenger ribonucleoprotein (FMRP) causes fragile X syndrome (FXS), the most prevalent form of inherited intellectual disability. Here, we show that FMRP interacts with the voltage-dependent anion channel (VDAC) to regulate the formation and function of endoplasmic reticulum (ER)-mitochondria contact sites (ERMCSs), structures that are critical for mitochondrial calcium (mito-Ca2+) homeostasis. FMRP-deficient cells feature excessive ERMCS formation and ER-to-mitochondria Ca2+ transfer. Genetic and pharmacological inhibition of VDAC or other ERMCS components restored synaptic structure, function, and plasticity and rescued locomotion and cognitive deficits of the Drosophila dFmr1 mutant. Expressing FMRP C-terminal domain (FMRP-C), which confers FMRP-VDAC interaction, rescued the ERMCS formation and mito-Ca2+ homeostasis defects in FXS patient iPSC-derived neurons and locomotion and cognitive deficits in Fmr1 knockout mice. These results identify altered ERMCS formation and mito-Ca2+ homeostasis as contributors to FXS and offer potential therapeutic targets.
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Affiliation(s)
- Ji Geng
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Tejinder Pal Khaket
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jie Pan
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Wen Li
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Yan Zhang
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Key Laboratory of Psychotic Disorders (No. 13dz2260500), Shanghai Mental Health Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Yong Ping
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Key Laboratory of Psychotic Disorders (No. 13dz2260500), Shanghai Mental Health Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200030, China
| | | | - Bingwei Lu
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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18
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Grasskamp AT, Jusyte M, McCarthy AW, Götz TWB, Ditlevsen S, Walter AM. Spontaneous neurotransmission at evocable synapses predicts their responsiveness to action potentials. Front Cell Neurosci 2023; 17:1129417. [PMID: 36970416 PMCID: PMC10030884 DOI: 10.3389/fncel.2023.1129417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 02/16/2023] [Indexed: 03/29/2023] Open
Abstract
Synaptic transmission relies on presynaptic neurotransmitter (NT) release from synaptic vesicles (SVs) and on NT detection by postsynaptic receptors. Transmission exists in two principal modes: action-potential (AP) evoked and AP-independent, "spontaneous" transmission. AP-evoked neurotransmission is considered the primary mode of inter-neuronal communication, whereas spontaneous transmission is required for neuronal development, homeostasis, and plasticity. While some synapses appear dedicated to spontaneous transmission only, all AP-responsive synapses also engage spontaneously, but whether this encodes functional information regarding their excitability is unknown. Here we report on functional interdependence of both transmission modes at individual synaptic contacts of Drosophila larval neuromuscular junctions (NMJs) which were identified by the presynaptic scaffolding protein Bruchpilot (BRP) and whose activities were quantified using the genetically encoded Ca2+ indicator GCaMP. Consistent with the role of BRP in organizing the AP-dependent release machinery (voltage-dependent Ca2+ channels and SV fusion machinery), most active BRP-positive synapses (>85%) responded to APs. At these synapses, the level of spontaneous activity was a predictor for their responsiveness to AP-stimulation. AP-stimulation resulted in cross-depletion of spontaneous activity and both transmission modes were affected by the non-specific Ca2+ channel blocker cadmium and engaged overlapping postsynaptic receptors. Thus, by using overlapping machinery, spontaneous transmission is a continuous, stimulus independent predictor for the AP-responsiveness of individual synapses.
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Affiliation(s)
| | - Meida Jusyte
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
- Einstein Center for Neurosciences, Charité–Universitätsmedizin Berlin, Berlin, Germany
| | | | - Torsten W. B. Götz
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | - Susanne Ditlevsen
- Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Alexander M. Walter
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
- Einstein Center for Neurosciences, Charité–Universitätsmedizin Berlin, Berlin, Germany
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
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19
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Ghelani T, Escher M, Thomas U, Esch K, Lützkendorf J, Depner H, Maglione M, Parutto P, Gratz S, Matkovic-Rachid T, Ryglewski S, Walter AM, Holcman D, O‘Connor Giles K, Heine M, Sigrist SJ. Interactive nanocluster compaction of the ELKS scaffold and Cacophony Ca 2+ channels drives sustained active zone potentiation. SCIENCE ADVANCES 2023; 9:eade7804. [PMID: 36800417 PMCID: PMC9937578 DOI: 10.1126/sciadv.ade7804] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 01/17/2023] [Indexed: 06/01/2023]
Abstract
At presynaptic active zones (AZs), conserved scaffold protein architectures control synaptic vesicle (SV) release by defining the nanoscale distribution and density of voltage-gated Ca2+ channels (VGCCs). While AZs can potentiate SV release in the minutes range, we lack an understanding of how AZ scaffold components and VGCCs engage into potentiation. We here establish dynamic, intravital single-molecule imaging of endogenously tagged proteins at Drosophila AZs undergoing presynaptic homeostatic potentiation. During potentiation, the numbers of α1 VGCC subunit Cacophony (Cac) increased per AZ, while their mobility decreased and nanoscale distribution compacted. These dynamic Cac changes depended on the interaction between Cac channel's intracellular carboxyl terminus and the membrane-close amino-terminal region of the ELKS-family protein Bruchpilot, whose distribution compacted drastically. The Cac-ELKS/Bruchpilot interaction was also needed for sustained AZ potentiation. Our single-molecule analysis illustrates how the AZ scaffold couples to VGCC nanoscale distribution and dynamics to establish a state of sustained potentiation.
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Affiliation(s)
- Tina Ghelani
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
- Molecular and Theoretical Neuroscience Leibniz-Forschungs Institut für Molekulare Pharmakologie (FMP) im CharitéCrossOver (CCO) Charité–University Medicine Berlin Charité Campus Mitte, Charité Platz, 110117 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
| | - Marc Escher
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Ulrich Thomas
- Department of Cellular Neurobiology, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany
| | - Klara Esch
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Janine Lützkendorf
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Harald Depner
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Marta Maglione
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
- Institute for Chemistry and Biochemistry, SupraFAB, Freie Universität Berlin, Altensteinstr. 23a, 14195 Berlin, Germany
| | - Pierre Parutto
- Group of Applied Mathematics and Computational Biology, IBENS, Ecole Normale Superieure, Paris, France
- Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Cambridge CB2 0AH, UK
- Churchill College, University of Cambridge, Cambridge CB3 0DS, UK
| | - Scott Gratz
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Tanja Matkovic-Rachid
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Stefanie Ryglewski
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Alexander M. Walter
- Molecular and Theoretical Neuroscience Leibniz-Forschungs Institut für Molekulare Pharmakologie (FMP) im CharitéCrossOver (CCO) Charité–University Medicine Berlin Charité Campus Mitte, Charité Platz, 110117 Berlin, Germany
- Department of Neuroscience, University of Copenhagen, Copenhagen 2200, Denmark
| | - David Holcman
- Group of Applied Mathematics and Computational Biology, IBENS, Ecole Normale Superieure, Paris, France
- Churchill College, University of Cambridge, Cambridge CB3 0DS, UK
| | - Kate O‘Connor Giles
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
- Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA
| | - Martin Heine
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
- Research Group Molecular Physiology, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany
| | - Stephan J. Sigrist
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
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20
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Cunningham KL, Littleton JT. Mechanisms controlling the trafficking, localization, and abundance of presynaptic Ca 2+ channels. Front Mol Neurosci 2023; 15:1116729. [PMID: 36710932 PMCID: PMC9880069 DOI: 10.3389/fnmol.2022.1116729] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 12/26/2022] [Indexed: 01/14/2023] Open
Abstract
Voltage-gated Ca2+ channels (VGCCs) mediate Ca2+ influx to trigger neurotransmitter release at specialized presynaptic sites termed active zones (AZs). The abundance of VGCCs at AZs regulates neurotransmitter release probability (Pr ), a key presynaptic determinant of synaptic strength. Given this functional significance, defining the processes that cooperate to establish AZ VGCC abundance is critical for understanding how these mechanisms set synaptic strength and how they might be regulated to control presynaptic plasticity. VGCC abundance at AZs involves multiple steps, including channel biosynthesis (transcription, translation, and trafficking through the endomembrane system), forward axonal trafficking and delivery to synaptic terminals, incorporation and retention at presynaptic sites, and protein recycling. Here we discuss mechanisms that control VGCC abundance at synapses, highlighting findings from invertebrate and vertebrate models.
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Affiliation(s)
- Karen L. Cunningham
- The Picower Institute for Learning and Memory, Department of Biology, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
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21
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Armstrong NS, Frank CA. The calcineurin regulator Sarah enables distinct forms of homeostatic plasticity at the Drosophila neuromuscular junction. Front Synaptic Neurosci 2023; 14:1033743. [PMID: 36685082 PMCID: PMC9846150 DOI: 10.3389/fnsyn.2022.1033743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 12/05/2022] [Indexed: 01/05/2023] Open
Abstract
Introduction: The ability of synapses to maintain physiological levels of evoked neurotransmission is essential for neuronal stability. A variety of perturbations can disrupt neurotransmission, but synapses often compensate for disruptions and work to stabilize activity levels, using forms of homeostatic synaptic plasticity. Presynaptic homeostatic potentiation (PHP) is one such mechanism. PHP is expressed at the Drosophila melanogaster larval neuromuscular junction (NMJ) synapse, as well as other NMJs. In PHP, presynaptic neurotransmitter release increases to offset the effects of impairing muscle transmitter receptors. Prior Drosophila work has studied PHP using different ways to perturb muscle receptor function-either acutely (using pharmacology) or chronically (using genetics). Some of our prior data suggested that cytoplasmic calcium signaling was important for expression of PHP after genetic impairment of glutamate receptors. Here we followed up on that observation. Methods: We used a combination of transgenic Drosophila RNA interference and overexpression lines, along with NMJ electrophysiology, synapse imaging, and pharmacology to test if regulators of the calcium/calmodulin-dependent protein phosphatase calcineurin are necessary for the normal expression of PHP. Results: We found that either pre- or postsynaptic dysregulation of a Drosophila gene regulating calcineurin, sarah (sra), blocks PHP. Tissue-specific manipulations showed that either increases or decreases in sra expression are detrimental to PHP. Additionally, pharmacologically and genetically induced forms of expression of PHP are functionally separable depending entirely upon which sra genetic manipulation is used. Surprisingly, dual-tissue pre- and postsynaptic sra knockdown or overexpression can ameliorate PHP blocks revealed in single-tissue experiments. Pharmacological and genetic inhibition of calcineurin corroborated this latter finding. Discussion: Our results suggest tight calcineurin regulation is needed across multiple tissue types to stabilize peripheral synaptic outputs.
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Affiliation(s)
- Noah S. Armstrong
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA, United States,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA, United States
| | - C. Andrew Frank
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA, United States,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA, United States,Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, United States,*Correspondence: C. Andrew Frank
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22
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Parker D. Neurobiological reduction: From cellular explanations of behavior to interventions. Front Psychol 2022; 13:987101. [PMID: 36619115 PMCID: PMC9815460 DOI: 10.3389/fpsyg.2022.987101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 11/28/2022] [Indexed: 12/24/2022] Open
Abstract
Scientific reductionism, the view that higher level functions can be explained by properties at some lower-level or levels, has been an assumption of nervous system analyses since the acceptance of the neuron doctrine in the late 19th century, and became a dominant experimental approach with the development of intracellular recording techniques in the mid-20th century. Subsequent refinements of electrophysiological approaches and the continual development of molecular and genetic techniques have promoted a focus on molecular and cellular mechanisms in experimental analyses and explanations of sensory, motor, and cognitive functions. Reductionist assumptions have also influenced our views of the etiology and treatment of psychopathologies, and have more recently led to claims that we can, or even should, pharmacologically enhance the normal brain. Reductionism remains an area of active debate in the philosophy of science. In neuroscience and psychology, the debate typically focuses on the mind-brain question and the mechanisms of cognition, and how or if they can be explained in neurobiological terms. However, these debates are affected by the complexity of the phenomena being considered and the difficulty of obtaining the necessary neurobiological detail. We can instead ask whether features identified in neurobiological analyses of simpler aspects in simpler nervous systems support current molecular and cellular approaches to explaining systems or behaviors. While my view is that they do not, this does not invite the opposing view prevalent in dichotomous thinking that molecular and cellular detail is irrelevant and we should focus on computations or representations. We instead need to consider how to address the long-standing dilemma of how a nervous system that ostensibly functions through discrete cell to cell communication can generate population effects across multiple spatial and temporal scales to generate behavior.
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23
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Dannhäuser S, Mrestani A, Gundelach F, Pauli M, Komma F, Kollmannsberger P, Sauer M, Heckmann M, Paul MM. Endogenous tagging of Unc-13 reveals nanoscale reorganization at active zones during presynaptic homeostatic potentiation. Front Cell Neurosci 2022; 16:1074304. [PMID: 36589286 PMCID: PMC9797049 DOI: 10.3389/fncel.2022.1074304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 11/23/2022] [Indexed: 12/15/2022] Open
Abstract
Introduction Neurotransmitter release at presynaptic active zones (AZs) requires concerted protein interactions within a dense 3D nano-hemisphere. Among the complex protein meshwork the (M)unc-13 family member Unc-13 of Drosophila melanogaster is essential for docking of synaptic vesicles and transmitter release. Methods We employ minos-mediated integration cassette (MiMIC)-based gene editing using GFSTF (EGFP-FlAsH-StrepII-TEV-3xFlag) to endogenously tag all annotated Drosophila Unc-13 isoforms enabling visualization of endogenous Unc-13 expression within the central and peripheral nervous system. Results and discussion Electrophysiological characterization using two-electrode voltage clamp (TEVC) reveals that evoked and spontaneous synaptic transmission remain unaffected in unc-13 GFSTF 3rd instar larvae and acute presynaptic homeostatic potentiation (PHP) can be induced at control levels. Furthermore, multi-color structured-illumination shows precise co-localization of Unc-13GFSTF, Bruchpilot, and GluRIIA-receptor subunits within the synaptic mesoscale. Localization microscopy in combination with HDBSCAN algorithms detect Unc-13GFSTF subclusters that move toward the AZ center during PHP with unaltered Unc-13GFSTF protein levels.
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Affiliation(s)
- Sven Dannhäuser
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Achmed Mrestani
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
- Department of Neurology, Leipzig University Medical Center, Leipzig, Germany
- Division of General Biochemistry, Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Florian Gundelach
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
- Center of Mental Health, Department of Psychiatry, Psychotherapy, and Psychosomatics, University Hospital of Würzburg, Würzburg, Germany
| | - Martin Pauli
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Fabian Komma
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Philip Kollmannsberger
- Center for Computational and Theoretical Biology, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Manfred Heckmann
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Mila M Paul
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
- Department of Orthopedic Trauma, Hand, Plastic and Reconstructive Surgery, University Hospital of Würzburg, Würzburg, Germany
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24
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Perry S, Han Y, Qiu C, Chien C, Goel P, Nishimura S, Sajnani M, Schmid A, Sigrist SJ, Dickman D. A glutamate receptor C-tail recruits CaMKII to suppress retrograde homeostatic signaling. Nat Commun 2022; 13:7656. [PMID: 36496500 PMCID: PMC9741633 DOI: 10.1038/s41467-022-35417-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 12/02/2022] [Indexed: 12/13/2022] Open
Abstract
Presynaptic homeostatic plasticity (PHP) adaptively enhances neurotransmitter release following diminished postsynaptic glutamate receptor (GluR) functionality to maintain synaptic strength. While much is known about PHP expression mechanisms, postsynaptic induction remains enigmatic. For over 20 years, diminished postsynaptic Ca2+ influx was hypothesized to reduce CaMKII activity and enable retrograde PHP signaling at the Drosophila neuromuscular junction. Here, we have interrogated inductive signaling and find that active CaMKII colocalizes with and requires the GluRIIA receptor subunit. Next, we generated Ca2+-impermeable GluRs to reveal that both CaMKII activity and PHP induction are Ca2+-insensitive. Rather, a GluRIIA C-tail domain is necessary and sufficient to recruit active CaMKII. Finally, chimeric receptors demonstrate that the GluRIIA tail constitutively occludes retrograde homeostatic signaling by stabilizing active CaMKII. Thus, the physical loss of the GluRIIA tail is sensed, rather than reduced Ca2+, to enable retrograde PHP signaling, highlighting a unique, Ca2+-independent control mechanism for CaMKII in gating homeostatic plasticity.
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Affiliation(s)
- Sarah Perry
- Department of Neurobiology, University of Southern California, Los Angeles, CA, USA
| | - Yifu Han
- Department of Neurobiology, University of Southern California, Los Angeles, CA, USA
| | - Chengjie Qiu
- Department of Neurobiology, University of Southern California, Los Angeles, CA, USA
| | - Chun Chien
- Department of Neurobiology, University of Southern California, Los Angeles, CA, USA
| | - Pragya Goel
- Department of Neurobiology, University of Southern California, Los Angeles, CA, USA
| | - Samantha Nishimura
- Department of Neurobiology, University of Southern California, Los Angeles, CA, USA
| | - Manisha Sajnani
- Department of Neurobiology, University of Southern California, Los Angeles, CA, USA
| | - Andreas Schmid
- Institute for Biology/Genetics, Freie Universität Berlin, Takustraße 6, 14195, Berlin, Germany
- Faculty of Life Sciences, Albstadt-Sigmaringen University, Sigmaringen, Germany
| | - Stephan J Sigrist
- Institute for Biology/Genetics, Freie Universität Berlin, Takustraße 6, 14195, Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117, Berlin, Germany
| | - Dion Dickman
- Department of Neurobiology, University of Southern California, Los Angeles, CA, USA.
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25
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Mushtaq Z, Aavula K, Lasser DA, Kieweg ID, Lion LM, Kins S, Pielage J. Madm/NRBP1 mediates synaptic maintenance and neurodegeneration-induced presynaptic homeostatic potentiation. Cell Rep 2022; 41:111710. [PMID: 36450258 DOI: 10.1016/j.celrep.2022.111710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/05/2022] [Accepted: 11/02/2022] [Indexed: 12/03/2022] Open
Abstract
The precise regulation of synaptic connectivity and function is essential to maintain neuronal circuits. Here, we show that the Drosophila pseudo-kinase Madm/NRBP1 (Mlf-1-adapter-molecule/nuclear-receptor-binding protein 1) is required presynaptically to maintain synaptic stability and to coordinate synaptic growth and function. Presynaptic Madm mediates these functions by controlling cap-dependent translation via the target of rapamycin (TOR) effector 4E-BP/Thor (eukaryotic initiation factor 4E binding protein/Thor). Strikingly, at degenerating neuromuscular synapses, postsynaptic Madm induces a compensatory, transsynaptic signal that utilizes the presynaptic homeostatic potentiation (PHP) machinery to offset synaptic release deficits and to delay synaptic degeneration. Madm is not required for canonical PHP but induces a neurodegeneration-specific form of PHP and acts via the regulation of the cap-dependent translation regulators 4E-BP/Thor and S6-kinase. Consistently, postsynaptic induction of canonical PHP or TOR activation can compensate for postsynaptic Madm to alleviate functional and structural synaptic defects. Our results provide insights into the molecular mechanisms underlying neurodegeneration-induced PHP with potential neurotherapeutic applications.
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Affiliation(s)
- Zeeshan Mushtaq
- Department of Zoology and Neurobiology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Kumar Aavula
- Department of Zoology and Neurobiology, University of Kaiserslautern, 67663 Kaiserslautern, Germany; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland.
| | - Dario A Lasser
- Department of Zoology and Neurobiology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Ingrid D Kieweg
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Lena M Lion
- Department of Zoology and Neurobiology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Stefan Kins
- Department of Human Biology and Human Genetics, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Jan Pielage
- Department of Zoology and Neurobiology, University of Kaiserslautern, 67663 Kaiserslautern, Germany.
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26
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Orr BO, Fetter RD, Davis GW. Activation and expansion of presynaptic signaling foci drives presynaptic homeostatic plasticity. Neuron 2022; 110:3743-3759.e6. [PMID: 36087584 PMCID: PMC9671843 DOI: 10.1016/j.neuron.2022.08.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 06/07/2022] [Accepted: 08/11/2022] [Indexed: 12/15/2022]
Abstract
Presynaptic homeostatic plasticity (PHP) adaptively regulates synaptic transmission in health and disease. Despite identification of numerous genes that are essential for PHP, we lack a dynamic framework to explain how PHP is initiated, potentiated, and limited to achieve precise control of vesicle fusion. Here, utilizing both mice and Drosophila, we demonstrate that PHP progresses through the assembly and physical expansion of presynaptic signaling foci where activated integrins biochemically converge with trans-synaptic Semaphorin2b/PlexinB signaling. Each component of the identified signaling complexes, including alpha/beta-integrin, Semaphorin2b, PlexinB, talin, and focal adhesion kinase (FAK), and their biochemical interactions, are essential for PHP. Complex integrity requires the Sema2b ligand and complex expansion includes a ∼2.5-fold expansion of active-zone associated puncta composed of the actin-binding protein talin. Finally, complex pre-expansion is sufficient to accelerate the rate and extent of PHP. A working model is proposed incorporating signal convergence with dynamic molecular assemblies that instruct PHP.
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Affiliation(s)
- Brian O Orr
- Department of Biochemistry and Biophysics, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158 USA
| | - Richard D Fetter
- Department of Biochemistry and Biophysics, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158 USA
| | - Graeme W Davis
- Department of Biochemistry and Biophysics, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158 USA.
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27
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Drion C. Homeostatic Control of Neuronal Activity. Physiology (Bethesda) 2022. [DOI: 10.5772/intechopen.108577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
For healthy brain functioning, it is crucial that neuronal networks do not become hyperactive, but also, that they remain excitable. Homeostatic mechanisms ensure that neuronal activity remains within a functional range. How does that work? In this chapter, we will explore homeostatic control of neuronal activity. We will start by introducing the basics of neuronal communication to establish what makes a neuron excitable. Then, we will learn how neurons are able to tune their own excitability, which is called homeostatic intrinsic plasticity. Next, we will discuss the ability of neurons to tune the strength of their connections to other neurons. This is called homeostatic synaptic plasticity and involves synaptic scaling, the up- and downregulation of receptors, and the control of neurotransmitter release. Finally, we will review the role of glia in neuronal network homeostasis and discuss disorders where the homeostatic control of neuronal activity is compromised.
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28
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Abstract
Robust neural information transfer relies on a delicate molecular nano-architecture of chemical synapses. Neurotransmitter release is controlled by a specific arrangement of proteins within presynaptic active zones. How the specific presynaptic molecular architecture relates to postsynaptic organization and how synaptic nano-architecture is transsynaptically regulated to enable stable synaptic transmission remain enigmatic. Using time-gated stimulated emission-depletion microscopy at the Drosophila neuromuscular junction, we found that presynaptic nanorings formed by the active-zone scaffold Bruchpilot (Brp) align with postsynaptic glutamate receptor (GluR) rings. Individual rings harbor approximately four transsynaptically aligned Brp-GluR nanocolumns. Similar nanocolumn rings are formed by the presynaptic protein Unc13A and GluRs. Intriguingly, acute GluR impairment triggers transsynaptic nanocolumn formation on the minute timescale during homeostatic plasticity. We reveal distinct phases of structural transsynaptic homeostatic plasticity, with postsynaptic GluR reorganization preceding presynaptic Brp modulation. Finally, homeostatic control of transsynaptic nano-architecture and neurotransmitter release requires the auxiliary GluR subunit Neto. Thus, transsynaptic nanocolumn rings provide a substrate for rapid homeostatic stabilization of synaptic efficacy.
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29
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Xiao J, Meng X, Chen K, Wang J, Wu L, Chen Y, Yu X, Feng J, Li Z. Down-Regulation of Double C2 Domain Alpha Promotes the Formation of Hyperplastic Nerve Fibers in Aganglionic Segments of Hirschsprung’s Disease. Int J Mol Sci 2022; 23:ijms231810204. [PMID: 36142117 PMCID: PMC9499397 DOI: 10.3390/ijms231810204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 11/22/2022] Open
Abstract
Hirschsprung’s disease (HSCR) is a common developmental anomaly of the gastrointestinal tract in children. The most significant characteristics of aganglionic segments in HSCR are hyperplastic extrinsic nerve fibers and the absence of endogenous ganglion plexus. Double C2 domain alpha (DOC2A) is mainly located in the nucleus and is involved in Ca2+-dependent neurotransmitter release. The loss function of DOC2A influences postsynaptic protein synthesis, dendrite morphology, postsynaptic receptor density and synaptic plasticity. It is still unknown why hyperplastic extrinsic nerve fibers grow into aganglionic segments in HSCR. We detected the expression of DOC2A in HSCR aganglionic segment colons and established three DOC2A-knockdown models in the Neuro-2a cell line, neural spheres and zebrafish separately. First, we detected the protein and mRNA expression of DOC2A and found that DOC2A was negatively correlated with AChE+ grades. Second, in the Neuro-2a cell lines, we found that the amount of neurite outgrowth and mean area per cell were significantly increased, which suggested that the inhibition of DOC2A promotes nerve fiber formation and the neuron’s polarity. In the neural spheres, we found that the DOC2A knockdown was manifested by a more obvious connection of nerve fibers in neural spheres. Then, we knocked down Doc2a in zebrafish and found that the down-regulation of Doc2a accelerates the formation of hyperplastic nerve fibers in aganglionic segments in zebrafish. Finally, we detected the expression of MUNC13-2 (UNC13B), which was obviously up-regulated in Grade3/4 (lower DOC2A expression) compared with Grade1/2 (higher DOC2A expression) in the circular muscle layer and longitudinal muscle layer. The expression of UNC13B was up-regulated with the knocking down of DOC2A, and there were protein interactions between DOC2A and UNC13B. The down-regulation of DOC2A may be an important factor leading to hyperplastic nerve fibers in aganglionic segments of HSCR. UNC13B seems to be a downstream molecule to DOC2A, which may participate in the spasm of aganglionic segments of HSCR patient colons.
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Affiliation(s)
- Jun Xiao
- Department of Pediatric Surgery, Tongji Hospital, Huazhong University of Science and Technology, Wuhan 430030, China
- Hubei Clinical Center of Hirschsprung’s Disease and Allied Disorders, Wuhan 430030, China
| | - Xinyao Meng
- Department of Pediatric Surgery, Tongji Hospital, Huazhong University of Science and Technology, Wuhan 430030, China
- Hubei Clinical Center of Hirschsprung’s Disease and Allied Disorders, Wuhan 430030, China
| | - Ke Chen
- Department of Pediatric Surgery, Tongji Hospital, Huazhong University of Science and Technology, Wuhan 430030, China
- Hubei Clinical Center of Hirschsprung’s Disease and Allied Disorders, Wuhan 430030, China
| | - Jing Wang
- Department of Pediatric Surgery, Tongji Hospital, Huazhong University of Science and Technology, Wuhan 430030, China
- Hubei Clinical Center of Hirschsprung’s Disease and Allied Disorders, Wuhan 430030, China
| | - Luyao Wu
- Department of Pediatric Surgery, Tongji Hospital, Huazhong University of Science and Technology, Wuhan 430030, China
- Hubei Clinical Center of Hirschsprung’s Disease and Allied Disorders, Wuhan 430030, China
| | - Yingjian Chen
- Department of Pediatric Surgery, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou 350001, China
| | - Xiaosi Yu
- Department of Pediatric Surgery, Tongji Hospital, Huazhong University of Science and Technology, Wuhan 430030, China
- Hubei Clinical Center of Hirschsprung’s Disease and Allied Disorders, Wuhan 430030, China
| | - Jiexiong Feng
- Department of Pediatric Surgery, Tongji Hospital, Huazhong University of Science and Technology, Wuhan 430030, China
- Hubei Clinical Center of Hirschsprung’s Disease and Allied Disorders, Wuhan 430030, China
- Correspondence: (J.F.); (Z.L.)
| | - Zhi Li
- Department of Pediatric Surgery, Tongji Hospital, Huazhong University of Science and Technology, Wuhan 430030, China
- Hubei Clinical Center of Hirschsprung’s Disease and Allied Disorders, Wuhan 430030, China
- Correspondence: (J.F.); (Z.L.)
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30
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Han Y, Chien C, Goel P, He K, Pinales C, Buser C, Dickman D. Botulinum neurotoxin accurately separates tonic vs. phasic transmission and reveals heterosynaptic plasticity rules in Drosophila. eLife 2022; 11:e77924. [PMID: 35993544 PMCID: PMC9439677 DOI: 10.7554/elife.77924] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 08/20/2022] [Indexed: 11/13/2022] Open
Abstract
In developing and mature nervous systems, diverse neuronal subtypes innervate common targets to establish, maintain, and modify neural circuit function. A major challenge towards understanding the structural and functional architecture of neural circuits is to separate these inputs and determine their intrinsic and heterosynaptic relationships. The Drosophila larval neuromuscular junction is a powerful model system to study these questions, where two glutamatergic motor neurons, the strong phasic-like Is and weak tonic-like Ib, co-innervate individual muscle targets to coordinate locomotor behavior. However, complete neurotransmission from each input has never been electrophysiologically separated. We have employed a botulinum neurotoxin, BoNT-C, that eliminates both spontaneous and evoked neurotransmission without perturbing synaptic growth or structure, enabling the first approach that accurately isolates input-specific neurotransmission. Selective expression of BoNT-C in Is or Ib motor neurons disambiguates the functional properties of each input. Importantly, the blended values of Is+Ib neurotransmission can be fully recapitulated by isolated physiology from each input. Finally, selective silencing by BoNT-C does not induce heterosynaptic structural or functional plasticity at the convergent input. Thus, BoNT-C establishes the first approach to accurately separate neurotransmission between tonic vs. phasic neurons and defines heterosynaptic plasticity rules in a powerful model glutamatergic circuit.
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Affiliation(s)
- Yifu Han
- Department of Neurobiology, University of Southern CaliforniaLos AngelesUnited States
| | - Chun Chien
- Department of Neurobiology, University of Southern CaliforniaLos AngelesUnited States
| | - Pragya Goel
- Department of Neurobiology, University of Southern CaliforniaLos AngelesUnited States
| | - Kaikai He
- Department of Neurobiology, University of Southern CaliforniaLos AngelesUnited States
| | | | | | - Dion Dickman
- Department of Neurobiology, University of Southern CaliforniaLos AngelesUnited States
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31
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Rue MC, Alonso LM, Marder E. Repeated applications of high potassium elicit long-term changes in a motor circuit from the crab, Cancer borealis. iScience 2022; 25:104919. [PMID: 36060056 PMCID: PMC9436765 DOI: 10.1016/j.isci.2022.104919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/12/2022] [Accepted: 08/08/2022] [Indexed: 12/04/2022] Open
Abstract
We examined the effects of altered extracellular potassium concentration on the output of the well-studied pyloric circuit in the crab, Cancer borealis. Pyloric neurons initially become quiescent, then recover spiking and bursting activity in high potassium saline (2.5x[K+]). These changes in circuit robustness are maintained after the perturbation is removed; pyloric neurons are more robust to subsequent potassium perturbations even after several hours of wash in control saline. Despite this long-term "memory" of the stimulus history, we found no differences in neuronal activity in control saline. The circuit's adaptation is erased by both low potassium saline (0.4x[K+]) and direct hyperpolarizing current. Initial sensitivity of PD neurons to high potassium saline also varies seasonally, indicating that changes in robustness may reflect natural changes in circuit states. Thus, perturbation, followed by recovery of normal activity, can hide cryptic changes in neuronal properties that are only revealed by subsequent challenges.
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Affiliation(s)
- Mara C.P. Rue
- Biology Department and Volen Center, Brandeis University, Waltham, MA 02454, USA
| | - Leandro M. Alonso
- Biology Department and Volen Center, Brandeis University, Waltham, MA 02454, USA
| | - Eve Marder
- Biology Department and Volen Center, Brandeis University, Waltham, MA 02454, USA,Corresponding author
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Baccino-Calace M, Schmidt K, Müller M. The E3 ligase Thin controls homeostatic plasticity through neurotransmitter release repression. eLife 2022; 11:71437. [PMID: 35796533 PMCID: PMC9299833 DOI: 10.7554/elife.71437] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 07/06/2022] [Indexed: 11/13/2022] Open
Abstract
Synaptic proteins and synaptic transmission are under homeostatic control, but the relationship between these two processes remains enigmatic. Here, we systematically investigated the role of E3 ubiquitin ligases, key regulators of protein degradation-mediated proteostasis, in presynaptic homeostatic plasticity (PHP). An electrophysiology-based genetic screen of 157 E3 ligase-encoding genes at the Drosophila neuromuscular junction identified thin, an ortholog of human tripartite motif-containing 32 (TRIM32), a gene implicated in several neurological disorders, including autism spectrum disorder and schizophrenia. We demonstrate that thin functions presynaptically during rapid and sustained PHP. Presynaptic thin negatively regulates neurotransmitter release under baseline conditions by limiting the number of release-ready vesicles, largely independent of gross morphological defects. We provide genetic evidence that thin controls release through dysbindin, a schizophrenia-susceptibility gene required for PHP. Thin and Dysbindin localize in proximity within presynaptic boutons, and Thin degrades Dysbindin in vitro. Thus, the E3 ligase Thin links protein degradation-dependent proteostasis of Dysbindin to homeostatic regulation of neurotransmitter release.
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Affiliation(s)
| | - Katharina Schmidt
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Martin Müller
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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33
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Tang F, Fan J, Zhang X, Zou Z, Xiao D, Li X. The Role of Vti1a in Biological Functions and Its Possible Role in Nervous System Disorders. Front Mol Neurosci 2022; 15:918664. [PMID: 35711736 PMCID: PMC9197314 DOI: 10.3389/fnmol.2022.918664] [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: 04/12/2022] [Accepted: 05/09/2022] [Indexed: 11/24/2022] Open
Abstract
Vesicle transport through interaction with t-SNAREs 1A (Vti1a), a member of the N-ethylmaleimide-sensitive factor attachment protein receptor protein family, is involved in cell signaling as a vesicular protein and mediates vesicle trafficking. Vti1a appears to have specific roles in neurons, primarily by regulating upstream neurosecretory events that mediate exocytotic proteins and the availability of secretory organelles, as well as regulating spontaneous synaptic transmission and postsynaptic efficacy to control neurosecretion. Vti1a also has essential roles in neural development, autophagy, and unconventional extracellular transport of neurons. Studies have shown that Vti1a dysfunction plays critical roles in pathological mechanisms of Hepatic encephalopathy by influencing spontaneous neurotransmission. It also may have an unknown role in amyotrophic lateral sclerosis. A VTI1A variant is associated with the risk of glioma, and the fusion product of the VTI1A gene and the adjacent TCF7L2 gene is involved in glioma development. This review summarizes Vti1a functions in neurons and highlights the role of Vti1a in the several nervous system disorders.
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Affiliation(s)
- Fajuan Tang
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, China
| | - Jiali Fan
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, China
| | - Xiaoyan Zhang
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, China
| | - Zhuan Zou
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, China
| | - Dongqiong Xiao
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, China
- Dongqiong Xiao,
| | - Xihong Li
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, China
- *Correspondence: Xihong Li,
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34
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Egashira Y, Kumade A, Ojida A, Ono F. Spontaneously Recycling Synaptic Vesicles Constitute Readily Releasable Vesicles in Intact Neuromuscular Synapses. J Neurosci 2022; 42:3523-3536. [PMID: 35332083 PMCID: PMC9053852 DOI: 10.1523/jneurosci.2005-21.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 03/08/2022] [Accepted: 03/10/2022] [Indexed: 12/14/2022] Open
Abstract
Emerging evidence shows that spontaneous synaptic transmission plays crucial roles on neuronal functions through presynaptic molecular mechanisms distinct from that of action potential (AP)-evoked transmission. However, whether the synaptic vesicle (SV) population undergoing the two forms of transmission is segregated remains controversial due in part to the conflicting results observed in cultured neurons. Here we address this issue in intact neuromuscular synapses using transgenic zebrafish larvae expressing two different indicators targeted in the SVs: a pH-sensitive fluorescent protein, pHluorin, and a tag protein, HaloTag. By establishing a quantitative measure of recycled SV fractions, we found that ∼85% of SVs were mobilized by high-frequency AP firings. In contrast, spontaneously recycling SVs were mobilized only from <8% of SVs with a time constant of 45 min at 25°C, although prolonged AP inhibition mobilized an additional population with a delayed onset. The mobilization of the early-onset population was less temperature-sensitive and resistant to tetanus toxin, whereas that of the late-onset population was more sensitive to temperature and was inhibited by tetanus toxin, indicating that prolonged AP inhibition activated a distinct molecular machinery for spontaneous SV fusion. Therefore, the early-onset population limited to <8% was likely the only source of spontaneous release that occurred physiologically. We further showed that this limited population was independent from those reluctant to fuse during AP firing and was used in both the hypertonic stimulation and the immediate phase of AP-evoked releases, thereby matching the characteristics of the readily releasable pool.SIGNIFICANCE STATEMENT Synaptic vesicles (SVs) are divided into functionally distinct pools depending on how they respond to action potential (AP) firing. The origin of SVs used for spontaneous fusion remains enigmatic despite intensive studies in cultured preparations. We addressed this question in intact neuromuscular synapses and provided two findings. First, prolonged AP inhibition activated a distinct population of fusion, which needs to be distinguished from genuine spontaneous fusion arising from a highly limited fraction. Second, the limited fraction observed early in the AP inhibition period exhibited the characteristics of readily releasable pool in the subsequent round of stimulation. Our study revealed that the origin of spontaneous SV fusion is restricted to the readily releasable pool among the SV pools involved in AP-evoked fusion.
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Affiliation(s)
- Yoshihiro Egashira
- Department of Physiology, Osaka Medical and Pharmaceutical University, Takatsuki, 569-8686, Japan
| | - Ayane Kumade
- Graduate School of Pharmaceutical Science, Kyushu University, Fukuoka, 812-8582, Japan
| | - Akio Ojida
- Graduate School of Pharmaceutical Science, Kyushu University, Fukuoka, 812-8582, Japan
| | - Fumihito Ono
- Department of Physiology, Osaka Medical and Pharmaceutical University, Takatsuki, 569-8686, Japan
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35
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Stahl A, Noyes NC, Boto T, Botero V, Broyles CN, Jing M, Zeng J, King LB, Li Y, Davis RL, Tomchik SM. Associative learning drives longitudinally graded presynaptic plasticity of neurotransmitter release along axonal compartments. eLife 2022; 11:76712. [PMID: 35285796 PMCID: PMC8956283 DOI: 10.7554/elife.76712] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 03/11/2022] [Indexed: 12/27/2022] Open
Abstract
Anatomical and physiological compartmentalization of neurons is a mechanism to increase the computational capacity of a circuit, and a major question is what role axonal compartmentalization plays. Axonal compartmentalization may enable localized, presynaptic plasticity to alter neuronal output in a flexible, experience-dependent manner. Here, we show that olfactory learning generates compartmentalized, bidirectional plasticity of acetylcholine release that varies across the longitudinal compartments of Drosophila mushroom body (MB) axons. The directionality of the learning-induced plasticity depends on the valence of the learning event (aversive vs. appetitive), varies linearly across proximal to distal compartments following appetitive conditioning, and correlates with learning-induced changes in downstream mushroom body output neurons (MBONs) that modulate behavioral action selection. Potentiation of acetylcholine release was dependent on the CaV2.1 calcium channel subunit cacophony. In addition, contrast between the positive conditioned stimulus and other odors required the inositol triphosphate receptor, which maintained responsivity to odors upon repeated presentations, preventing adaptation. Downstream from the MB, a set of MBONs that receive their input from the γ3 MB compartment were required for normal appetitive learning, suggesting that they represent a key node through which reward learning influences decision-making. These data demonstrate that learning drives valence-correlated, compartmentalized, bidirectional potentiation, and depression of synaptic neurotransmitter release, which rely on distinct mechanisms and are distributed across axonal compartments in a learning circuit.
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Affiliation(s)
- Aaron Stahl
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Nathaniel C Noyes
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Tamara Boto
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Valentina Botero
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Connor N Broyles
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Miao Jing
- Chinese Institute for Brain Research, Beijing, China
| | - Jianzhi Zeng
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China.,State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.,PKU IDG/McGovern Institute for Brain Research, Beijing, China
| | - Lanikea B King
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Yulong Li
- Chinese Institute for Brain Research, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China.,State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.,PKU IDG/McGovern Institute for Brain Research, Beijing, China
| | - Ronald L Davis
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Seth M Tomchik
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
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36
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Wenner PA, Pekala D. Homeostatic Regulation of Motoneuron Properties in Development. ADVANCES IN NEUROBIOLOGY 2022; 28:87-107. [PMID: 36066822 DOI: 10.1007/978-3-031-07167-6_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Homeostatic plasticity represents a set of compensatory mechanisms that are engaged following a perturbation to some feature of neuronal or network function. Homeostatic mechanisms are most robustly expressed during development, a period that is replete with various perturbations such as increased cell size and the addition/removal of synaptic connections. In this review we look at numerous studies that have advanced our understanding of homeostatic plasticity by taking advantage of the accessibility of developing motoneurons. We discuss the homeostatic regulation of embryonic movements in the living chick embryo and describe the spinal compensatory mechanisms that act to recover these movements (homeostatic intrinsic plasticity) or stabilize synaptic strength (synaptic scaling). We describe the expression and triggering mechanisms of these forms of homeostatic plasticity and thereby gain an understanding of their roles in the motor system. We then illustrate how these findings can be extended to studies of developing motoneurons in other systems including the rodents, zebrafish, and fly. Furthermore, studies in developing drosophila have been critical in identifying some of the molecular signaling cascades and expression mechanisms that underlie homeostatic intrinsic membrane excitability. This powerful model organism has also been used to study a presynaptic form of homeostatic plasticity where increases or decreases in synaptic transmission are associated with compensatory changes in probability of release at the neuromuscular junction. Further, we describe studies that demonstrate homeostatic adjustments of ion channel expression following perturbations to other kinds of ion channels. Finally, we discuss work in xenopus that shows a homeostatic regulation of neurotransmitter phenotype in developing motoneurons following activity perturbations. Together, this work illustrates the importance of developing motoneurons in elucidating the mechanisms and roles of homeostatic plasticity.
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Affiliation(s)
- Peter A Wenner
- Department of Cell Biology, Whitehead Biomedical Research Building, Emory University School of Medicine, Atlanta, GA, USA.
| | - Dobromila Pekala
- Department of Cell Biology, Whitehead Biomedical Research Building, Emory University School of Medicine, Atlanta, GA, USA
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37
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Nair AG, Muttathukunnel P, Müller M. Distinct molecular pathways govern presynaptic homeostatic plasticity. Cell Rep 2021; 37:110105. [PMID: 34910905 PMCID: PMC8692748 DOI: 10.1016/j.celrep.2021.110105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 10/05/2021] [Accepted: 11/16/2021] [Indexed: 11/30/2022] Open
Abstract
Presynaptic homeostatic plasticity (PHP) stabilizes synaptic transmission by counteracting impaired neurotransmitter receptor function through neurotransmitter release potentiation. PHP is thought to be triggered by impaired receptor function and to involve a stereotypic signaling pathway. However, here we demonstrate that different receptor perturbations that similarly reduce synaptic transmission result in different responses at the Drosophila neuromuscular junction. While receptor inhibition by the glutamate receptor (GluR) antagonist γ-D-glutamylglycine (γDGG) is not compensated by PHP, the GluR inhibitors Philanthotoxin-433 (PhTx) and Gyki-53655 (Gyki) induce compensatory PHP. Intriguingly, PHP triggered by PhTx and Gyki involve separable signaling pathways, including inhibition of distinct GluR subtypes, differential modulation of the active-zone scaffold Bruchpilot, and short-term plasticity. Moreover, while PHP upon Gyki treatment does not require genes promoting PhTx-induced PHP, it involves presynaptic protein kinase D. Thus, synapses not only respond differentially to similar activity impairments, but achieve homeostatic compensation via distinct mechanisms, highlighting the diversity of homeostatic signaling.
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Affiliation(s)
- Anu G Nair
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Department of Neuroscience, Karolinska Institute, 17177 Stockholm, Sweden
| | - Paola Muttathukunnel
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University of Zurich/ETH Zurich, 8057 Zurich, Switzerland
| | - Martin Müller
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University of Zurich/ETH Zurich, 8057 Zurich, Switzerland.
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38
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Dissanayake KN, Margetiny F, Whitmore CL, Chou RCC, Roesl C, Patel V, McArdle JJ, Webster R, Beeson D, Tattersall JEH, Wyllie DJA, Eddleston M, Ribchester RR. Antagonistic postsynaptic and presynaptic actions of cyclohexanol on neuromuscular synaptic transmission and function. J Physiol 2021; 599:5417-5449. [PMID: 34748643 DOI: 10.1113/jp281921] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 11/01/2021] [Indexed: 01/20/2023] Open
Abstract
Intentional ingestion of agricultural organophosphorus insecticides is a significant public health issue in rural Asia, causing thousands of deaths annually. Some survivors develop a severe, acute or delayed myasthenic syndrome. In animal models, similar myasthenia has been associated with increasing plasma concentration of one insecticide solvent metabolite, cyclohexanol. We investigated possible mechanisms using voltage and current recordings from mouse neuromuscular junctions (NMJs) and transfected human cell lines. Cyclohexanol (10-25 mM) reduced endplate potential (EPP) amplitudes by 10-40% and enhanced depression during repetitive (2-20 Hz) stimulation by up to 60%. EPP decay was prolonged more than twofold. Miniature EPPs were attenuated by more than 50%. Cyclohexanol inhibited whole-cell currents recorded from CN21 cells expressing human postjunctional acetylcholine receptors (hnAChR) with an IC50 of 3.74 mM. Cyclohexanol (10-20 mM) also caused prolonged episodes of reduced-current, multi-channel bursting in outside-out patch recordings from hnAChRs expressed in transfected HEK293T cells, reducing charge transfer by more than 50%. Molecular modelling indicated cyclohexanol binding (-6 kcal/mol) to a previously identified alcohol binding site on nicotinic AChR α-subunits. Cyclohexanol also increased quantal content of evoked transmitter release by ∼50%. In perineurial recordings, cyclohexanol selectively inhibited presynaptic K+ currents. Modelling indicated cyclohexanol binding (-3.8 kcal/mol) to voltage-sensitive K+ channels at the same site as tetraethylammonium (TEA). TEA (10 mM) blocked K+ channels more effectively than cyclohexanol but EPPs were more prolonged in 20 mM cyclohexanol. The results explain the pattern of neuromuscular dysfunction following ingestion of organophosphorus insecticides containing cyclohexanol precursors and suggest that cyclohexanol may facilitate investigation of mechanisms regulating synaptic strength at NMJs. KEY POINTS: Intentional ingestion of agricultural organophosphorus insecticides is a significant public health issue in rural Asia, causing thousands of deaths annually. Survivors may develop a severe myasthenic syndrome or paralysis, associated with increased plasma levels of cyclohexanol, an insecticide solvent metabolite. Analysis of synaptic transmission at neuromuscular junctions in isolated mouse skeletal muscle, using isometric tension recording and microelectrode recording of endplate voltages and currents, showed that cyclohexanol reduced postsynaptic sensitivity to acetylcholine neurotransmitter (reduced quantal size) while simultaneously enhancing evoked transmitter release (increased quantal content). Patch recording from transfected cell lines, together with molecular modelling, indicated that cyclohexanol causes selective, allosteric antagonism of postsynaptic nicotinic acetylcholine receptors and block of presynaptic K+ -channel function. The data provide insight into the cellular and molecular mechanisms of neuromuscular weakness following intentional ingestion of agricultural organophosphorus insecticides. Our findings also extend understanding of the effects of alcohols on synaptic transmission and homeostatic synaptic function.
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Affiliation(s)
- Kosala N Dissanayake
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Pharmacology, Toxicology and Therapeutics, Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Filip Margetiny
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | | | - Robert C-C Chou
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Cornelia Roesl
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Vishwendra Patel
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, State University of New Jersey, Newark, NJ, USA
| | - Joseph J McArdle
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, State University of New Jersey, Newark, NJ, USA
| | - Richard Webster
- Weatherall Institute for Molecular Medicine, Radcliffe Infirmary, Oxford, UK
| | - David Beeson
- Weatherall Institute for Molecular Medicine, Radcliffe Infirmary, Oxford, UK
| | | | - David J A Wyllie
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Centre for Brain Development and Repair, Institute for Stem Cell Biology and Regenerative Medicine, Bangalore, India
| | - Michael Eddleston
- Pharmacology, Toxicology and Therapeutics, Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
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39
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Sauvola CW, Akbergenova Y, Cunningham KL, Aponte-Santiago NA, Littleton JT. The decoy SNARE Tomosyn sets tonic versus phasic release properties and is required for homeostatic synaptic plasticity. eLife 2021; 10:e72841. [PMID: 34713802 PMCID: PMC8612732 DOI: 10.7554/elife.72841] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/27/2021] [Indexed: 12/14/2022] Open
Abstract
Synaptic vesicle (SV) release probability (Pr) is a key presynaptic determinant of synaptic strength established by cell-intrinsic properties and further refined by plasticity. To characterize mechanisms that generate Pr heterogeneity between distinct neuronal populations, we examined glutamatergic tonic (Ib) and phasic (Is) motoneurons in Drosophila with stereotyped differences in Pr and synaptic plasticity. We found the decoy soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) Tomosyn is differentially expressed between these motoneuron subclasses and contributes to intrinsic differences in their synaptic output. Tomosyn expression enables tonic release in Ib motoneurons by reducing SNARE complex formation and suppressing Pr to generate decreased levels of SV fusion and enhanced resistance to synaptic fatigue. In contrast, phasic release dominates when Tomosyn expression is low, enabling high intrinsic Pr at Is terminals at the expense of sustained release and robust presynaptic potentiation. In addition, loss of Tomosyn disrupts the ability of tonic synapses to undergo presynaptic homeostatic potentiation.
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Affiliation(s)
- Chad W Sauvola
- Department of Brain and Cognitive Sciences, The Picower Institute of Learning and Memory, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Yulia Akbergenova
- Department of Brain and Cognitive Sciences, The Picower Institute of Learning and Memory, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Karen L Cunningham
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | | | - J Troy Littleton
- Department of Brain and Cognitive Sciences, The Picower Institute of Learning and Memory, Massachusetts Institute of TechnologyCambridgeUnited States
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
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40
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Mrestani A, Pauli M, Kollmannsberger P, Repp F, Kittel RJ, Eilers J, Doose S, Sauer M, Sirén AL, Heckmann M, Paul MM. Active zone compaction correlates with presynaptic homeostatic potentiation. Cell Rep 2021; 37:109770. [PMID: 34610300 DOI: 10.1016/j.celrep.2021.109770] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 05/14/2021] [Accepted: 09/07/2021] [Indexed: 12/30/2022] Open
Abstract
Neurotransmitter release is stabilized by homeostatic plasticity. Presynaptic homeostatic potentiation (PHP) operates on timescales ranging from minute- to life-long adaptations and likely involves reorganization of presynaptic active zones (AZs). At Drosophila melanogaster neuromuscular junctions, earlier work ascribed AZ enlargement by incorporating more Bruchpilot (Brp) scaffold protein a role in PHP. We use localization microscopy (direct stochastic optical reconstruction microscopy [dSTORM]) and hierarchical density-based spatial clustering of applications with noise (HDBSCAN) to study AZ plasticity during PHP at the synaptic mesoscale. We find compaction of individual AZs in acute philanthotoxin-induced and chronic genetically induced PHP but unchanged copy numbers of AZ proteins. Compaction even occurs at the level of Brp subclusters, which move toward AZ centers, and in Rab3 interacting molecule (RIM)-binding protein (RBP) subclusters. Furthermore, correlative confocal and dSTORM imaging reveals how AZ compaction in PHP translates into apparent increases in AZ area and Brp protein content, as implied earlier.
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Affiliation(s)
- Achmed Mrestani
- Institute for Physiology, Department of Neurophysiology, Julius Maximilians University Würzburg, 97070 Würzburg, Germany; Department of Neurology, Leipzig University Medical Center, 04103 Leipzig, Germany
| | - Martin Pauli
- Institute for Physiology, Department of Neurophysiology, Julius Maximilians University Würzburg, 97070 Würzburg, Germany; Department of Neurosurgery, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Philip Kollmannsberger
- Center for Computational and Theoretical Biology, Julius Maximilians University Würzburg, 97074 Würzburg, Germany
| | - Felix Repp
- Institute for Physiology, Department of Neurophysiology, Julius Maximilians University Würzburg, 97070 Würzburg, Germany; Center for Computational and Theoretical Biology, Julius Maximilians University Würzburg, 97074 Würzburg, Germany; Department of Neurosurgery, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Robert J Kittel
- Institute for Physiology, Department of Neurophysiology, Julius Maximilians University Würzburg, 97070 Würzburg, Germany; Institute of Biology, Department of Animal Physiology, Leipzig University, 04103 Leipzig, Germany; Carl-Ludwig-Institute for Physiology, Leipzig University, 04103 Leipzig, Germany
| | - Jens Eilers
- Carl-Ludwig-Institute for Physiology, Leipzig University, 04103 Leipzig, Germany
| | - Sören Doose
- Department of Biotechnology and Biophysics, Julius Maximilians University Würzburg, 97074 Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Julius Maximilians University Würzburg, 97074 Würzburg, Germany
| | - Anna-Leena Sirén
- Institute for Physiology, Department of Neurophysiology, Julius Maximilians University Würzburg, 97070 Würzburg, Germany; Department of Neurosurgery, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Manfred Heckmann
- Institute for Physiology, Department of Neurophysiology, Julius Maximilians University Würzburg, 97070 Würzburg, Germany.
| | - Mila M Paul
- Institute for Physiology, Department of Neurophysiology, Julius Maximilians University Würzburg, 97070 Würzburg, Germany; Department of Orthopaedic Trauma, Hand, Plastic and Reconstructive Surgery, University Hospital of Würzburg, 97080 Würzburg, Germany.
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41
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Kaleb K, Pedrosa V, Clopath C. Network-centered homeostasis through inhibition maintains hippocampal spatial map and cortical circuit function. Cell Rep 2021; 36:109577. [PMID: 34433026 PMCID: PMC8411119 DOI: 10.1016/j.celrep.2021.109577] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 04/21/2021] [Accepted: 07/29/2021] [Indexed: 11/23/2022] Open
Abstract
Despite ongoing experiential change, neural activity maintains remarkable stability. Although this is thought to be mediated by homeostatic plasticity, what aspect of neural activity is conserved and how the flexibility necessary for learning and memory is maintained is not fully understood. Experimental studies suggest that there exists network-centered, in addition to the well-studied neuron-centered, control. Here we computationally study such a potential mechanism: input-dependent inhibitory plasticity (IDIP). In a hippocampal model, we show that IDIP can explain the emergence of active and silent place cells as well as remapping following silencing of active place cells. Furthermore, we show that IDIP can also stabilize recurrent dynamics while preserving firing rate heterogeneity and stimulus representation, as well as persistent activity after memory encoding. Hence, the establishment of global network balance with IDIP has diverse functional implications and may be able to explain experimental phenomena across different brain areas. Input-dependent inhibitory plasticity (IDIP) provides network-wide homeostasis IDIP can explain hippocampal remapping following place map silencing IDIP can also provide recurrent network homeostasis with firing rate diversity
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Affiliation(s)
- Klara Kaleb
- Bioengineering Department, Imperial College London, London, UK
| | - Victor Pedrosa
- Bioengineering Department, Imperial College London, London, UK; Sainsbury Wellcome Centre, UCL, London, UK
| | - Claudia Clopath
- Bioengineering Department, Imperial College London, London, UK.
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42
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Jin I, Kassabov S, Kandel ER, Hawkins RD. Possible novel features of synaptic regulation during long-term facilitation in Aplysia. ACTA ACUST UNITED AC 2021; 28:218-227. [PMID: 34131053 PMCID: PMC8212780 DOI: 10.1101/lm.053124.120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 04/23/2021] [Indexed: 11/24/2022]
Abstract
Most studies of molecular mechanisms of synaptic plasticity have focused on the sequence of changes either at individual synapses or in the cell nucleus. However, studies of long-term facilitation at Aplysia sensory neuron–motor neuron synapses in isolated cell culture suggest two additional features of facilitation. First, that there is also regulation of the number of synaptic contacts between two neurons, which may occur at the level of cell pair-specific branch points in the neuronal arbor. Branch points contain many molecules that are involved in protein synthesis-dependent long-term facilitation including neurotrophins and the RNA binding protein CPEB. Second, the regulation involves homeostatic feedback and tends to keep the total number of contacts between two neurons at a fairly constant level both at rest and following facilitation. That raises the question of how facilitation and homeostasis can coexist. A possible answer is suggested by the findings that they both involve spontaneous transmission and postsynaptic Ca2+, which can have bidirectional effects similar to LTP and LTD in hippocampus. In addition, long-term facilitation can involve a change in the set point of homeostasis, which could be encoded by plasticity molecules such as CPEB and/or PKM. A computational model based on these ideas can qualitatively simulate the basic features of both facilitation and homeostasis of the number of contacts.
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Affiliation(s)
- Iksung Jin
- Department of Neuroscience, Columbia University, New York, New York 10032, USA
| | - Stefan Kassabov
- Department of Neuroscience, Columbia University, New York, New York 10032, USA
| | - Eric R Kandel
- Department of Neuroscience, Columbia University, New York, New York 10032, USA.,New York State Psychiatric Institute, New York, New York 10032, USA.,Howard Hughes Medical Institute, New York, New York 10032, USA
| | - Robert D Hawkins
- Department of Neuroscience, Columbia University, New York, New York 10032, USA.,New York State Psychiatric Institute, New York, New York 10032, USA
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43
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Yeates CJ, Frank CA. Homeostatic Depression Shows Heightened Sensitivity to Synaptic Calcium. Front Cell Neurosci 2021; 15:618393. [PMID: 34025355 PMCID: PMC8139420 DOI: 10.3389/fncel.2021.618393] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 04/13/2021] [Indexed: 12/18/2022] Open
Abstract
Synapses and circuits rely on homeostatic forms of regulation in order to transmit meaningful information. The Drosophila melanogaster neuromuscular junction (NMJ) is a well-studied synapse that shows robust homeostatic control of function. Most prior studies of homeostatic plasticity at the NMJ have centered on presynaptic homeostatic potentiation (PHP). PHP happens when postsynaptic muscle neurotransmitter receptors are impaired, triggering retrograde signaling that causes an increase in presynaptic neurotransmitter release. As a result, normal levels of evoked excitation are maintained. The counterpart to PHP at the NMJ is presynaptic homeostatic depression (PHD). Overexpression of the Drosophila vesicular glutamate transporter (VGlut) causes an increase in the amplitude of spontaneous events. PHD happens when the synapse responds to the challenge by decreasing quantal content (QC) during evoked neurotransmissionagain, resulting in normal levels of postsynaptic excitation. We hypothesized that there may exist a class of molecules that affects both PHP and PHD. Impairment of any such molecule could hurt a synapses ability to respond to any significant homeostatic challenge. We conducted an electrophysiology-based screen for blocks of PHD. We did not observe a block of PHD in the genetic conditions screened, but we found loss-of-function conditions that led to a substantial deficit in evoked amplitude when combined with VGlut overexpression. The conditions causing this phenotype included a double heterozygous loss-of-function condition for genes encoding the inositol trisphosphate receptor (IP3R itpr) and ryanodine receptor (RyR). IP3Rs and RyRs gate calcium release from intracellular stores. Pharmacological agents targeting IP3R and RyR recapitulated the genetic losses of these factors, as did lowering calcium levels from other sources. Our data are consistent with the idea that the homeostatic signaling process underlying PHD is especially sensitive to levels of calcium at the presynapse.
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Affiliation(s)
- Catherine J Yeates
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA, United States.,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA, United States
| | - C Andrew Frank
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA, United States.,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA, United States.,Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, Iowa City, IA, United States
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44
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Han TH, Vicidomini R, Ramos CI, Wang Q, Nguyen P, Jarnik M, Lee CH, Stawarski M, Hernandez RX, Macleod GT, Serpe M. Neto-α Controls Synapse Organization and Homeostasis at the Drosophila Neuromuscular Junction. Cell Rep 2021; 32:107866. [PMID: 32640231 PMCID: PMC7484471 DOI: 10.1016/j.celrep.2020.107866] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 02/27/2020] [Accepted: 06/16/2020] [Indexed: 02/06/2023] Open
Abstract
Glutamate receptor auxiliary proteins control receptor distribution and function, ultimately controlling synapse assembly, maturation, and plasticity. At the Drosophila neuromuscular junction (NMJ), a synapse with both pre- and postsynaptic kainate-type glutamate receptors (KARs), we show that the auxiliary protein Neto evolved functionally distinct isoforms to modulate synapse development and homeostasis. Using genetics, cell biology, and electrophysiology, we demonstrate that Neto-α functions on both sides of the NMJ. In muscle, Neto-α limits the size of the postsynaptic receptor field. In motor neurons (MNs), Neto-α controls neurotransmitter release in a KAR-dependent manner. In addition, Neto-α is both required and sufficient for the presynaptic increase in neurotransmitter release in response to reduced postsynaptic sensitivity. This KAR-independent function of Neto-α is involved in activity-induced cytomatrix remodeling. We propose that Drosophila ensures NMJ functionality by acquiring two Neto isoforms with differential expression patterns and activities.
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Affiliation(s)
- Tae Hee Han
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Rosario Vicidomini
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Cathy Isaura Ramos
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA; Institute of Functional Genomics of Lyon, Lyon, France
| | - Qi Wang
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Peter Nguyen
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Michal Jarnik
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Chi-Hon Lee
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA; Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Michal Stawarski
- Wilkes Honors College and Department of Biology, Florida Atlantic University, Jupiter, FL, USA; Biomedical Department, University of Basel, Basel, Switzerland
| | - Roberto X Hernandez
- Wilkes Honors College and Department of Biology, Florida Atlantic University, Jupiter, FL, USA
| | - Gregory T Macleod
- Wilkes Honors College and Department of Biology, Florida Atlantic University, Jupiter, FL, USA
| | - Mihaela Serpe
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA.
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45
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Ruggiero A, Katsenelson M, Slutsky I. Mitochondria: new players in homeostatic regulation of firing rate set points. Trends Neurosci 2021; 44:605-618. [PMID: 33865626 DOI: 10.1016/j.tins.2021.03.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 02/10/2021] [Accepted: 03/11/2021] [Indexed: 10/21/2022]
Abstract
Neural circuit functions are stabilized by homeostatic processes at long timescales in response to changes in behavioral states, experience, and learning. However, it remains unclear which specific physiological variables are being stabilized and which cellular or neural network components compose the homeostatic machinery. At this point, most evidence suggests that the distribution of firing rates among neurons in a neuronal circuit is the key variable that is maintained around a set-point value in a process called 'firing rate homeostasis.' Here, we review recent findings that implicate mitochondria as central players in mediating firing rate homeostasis. While mitochondria are known to regulate neuronal variables such as synaptic vesicle release or intracellular calcium concentration, the mitochondrial signaling pathways that are essential for firing rate homeostasis remain largely unknown. We used basic concepts of control theory to build a framework for classifying possible components of the homeostatic machinery that stabilizes firing rate, and we particularly emphasize the potential role of sleep and wakefulness in this homeostatic process. This framework may facilitate the identification of new homeostatic pathways whose malfunctions drive instability of neural circuits in distinct brain disorders.
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Affiliation(s)
- Antonella Ruggiero
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Maxim Katsenelson
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Inna Slutsky
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, 69978 Tel Aviv, Israel.
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46
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Changes in Presynaptic Gene Expression during Homeostatic Compensation at a Central Synapse. J Neurosci 2021; 41:3054-3067. [PMID: 33608385 PMCID: PMC8026347 DOI: 10.1523/jneurosci.2979-20.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/27/2021] [Accepted: 01/28/2021] [Indexed: 12/02/2022] Open
Abstract
Homeostatic matching of pre- and postsynaptic function has been observed in many species and neural structures, but whether transcriptional changes contribute to this form of trans-synaptic coordination remains unknown. To identify genes whose expression is altered in presynaptic neurons as a result of perturbing postsynaptic excitability, we applied a transcriptomics-friendly, temperature-inducible Kir2.1-based activity clamp at the first synaptic relay of the Drosophila olfactory system, a central synapse known to exhibit trans-synaptic homeostatic matching. Twelve hours after adult-onset suppression of activity in postsynaptic antennal lobe projection neurons of males and females, we detected changes in the expression of many genes in the third antennal segment, which houses the somata of presynaptic olfactory receptor neurons. These changes affected genes with roles in synaptic vesicle release and synaptic remodeling, including several implicated in homeostatic plasticity at the neuromuscular junction. At 48 h and beyond, the transcriptional landscape tilted toward protein synthesis, folding, and degradation; energy metabolism; and cellular stress defenses, indicating that the system had been pushed to its homeostatic limits. Our analysis suggests that similar homeostatic machinery operates at peripheral and central synapses and identifies many of its components. The presynaptic transcriptional response to genetically targeted postsynaptic perturbations could be exploited for the construction of novel connectivity tracing tools. SIGNIFICANCE STATEMENT Homeostatic feedback mechanisms adjust intrinsic and synaptic properties of neurons to keep their average activity levels constant. We show that, at a central synapse in the fruit fly brain, these mechanisms include changes in presynaptic gene expression that are instructed by an abrupt loss of postsynaptic excitability. The trans-synaptically regulated genes have roles in synaptic vesicle release and synapse remodeling; protein synthesis, folding, and degradation; and energy metabolism. Our study establishes a role for transcriptional changes in homeostatic synaptic plasticity, points to mechanistic commonalities between peripheral and central synapses, and potentially opens new opportunities for the development of connectivity-based gene expression systems.
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Goel P, Dickman D. Synaptic homeostats: latent plasticity revealed at the Drosophila neuromuscular junction. Cell Mol Life Sci 2021; 78:3159-3179. [PMID: 33449150 PMCID: PMC8044042 DOI: 10.1007/s00018-020-03732-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/19/2020] [Accepted: 12/04/2020] [Indexed: 12/11/2022]
Abstract
Homeostatic signaling systems are fundamental forms of biological regulation that maintain stable functionality in a changing environment. In the nervous system, synapses are crucial substrates for homeostatic modulation, serving to establish, maintain, and modify the balance of excitation and inhibition. Synapses must be sufficiently flexible to enable the plasticity required for learning and memory but also endowed with the stability to last a lifetime. In response to the processes of development, growth, remodeling, aging, and disease that challenge synapses, latent forms of adaptive plasticity become activated to maintain synaptic stability. In recent years, new insights into the homeostatic control of synaptic function have been achieved using the powerful Drosophila neuromuscular junction (NMJ). This review will focus on work over the past 10 years that has illuminated the cellular and molecular mechanisms of five homeostats that operate at the fly NMJ. These homeostats adapt to loss of postsynaptic neurotransmitter receptor functionality, glutamate imbalance, axonal injury, as well as aberrant synaptic growth and target innervation. These diverse homeostats work independently yet can be simultaneously expressed to balance neurotransmission. Growing evidence from this model glutamatergic synapse suggests these ancient homeostatic signaling systems emerged early in evolution and are fundamental forms of plasticity that also function to stabilize mammalian cholinergic NMJs and glutamatergic central synapses.
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Affiliation(s)
- Pragya Goel
- Department of Neurobiology, University of Southern California, Los Angeles, CA, 90089, USA
| | - Dion Dickman
- Department of Neurobiology, University of Southern California, Los Angeles, CA, 90089, USA.
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48
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Aponte-Santiago NA, Littleton JT. Synaptic Properties and Plasticity Mechanisms of Invertebrate Tonic and Phasic Neurons. Front Physiol 2020; 11:611982. [PMID: 33391026 PMCID: PMC7772194 DOI: 10.3389/fphys.2020.611982] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/24/2020] [Indexed: 12/15/2022] Open
Abstract
Defining neuronal cell types and their associated biophysical and synaptic diversity has become an important goal in neuroscience as a mechanism to create comprehensive brain cell atlases in the post-genomic age. Beyond broad classification such as neurotransmitter expression, interneuron vs. pyramidal, sensory or motor, the field is still in the early stages of understanding closely related cell types. In both vertebrate and invertebrate nervous systems, one well-described distinction related to firing characteristics and synaptic release properties are tonic and phasic neuronal subtypes. In vertebrates, these classes were defined based on sustained firing responses during stimulation (tonic) vs. transient responses that rapidly adapt (phasic). In crustaceans, the distinction expanded to include synaptic release properties, with tonic motoneurons displaying sustained firing and weaker synapses that undergo short-term facilitation to maintain muscle contraction and posture. In contrast, phasic motoneurons with stronger synapses showed rapid depression and were recruited for short bursts during fast locomotion. Tonic and phasic motoneurons with similarities to those in crustaceans have been characterized in Drosophila, allowing the genetic toolkit associated with this model to be used for dissecting the unique properties and plasticity mechanisms for these neuronal subtypes. This review outlines general properties of invertebrate tonic and phasic motoneurons and highlights recent advances that characterize distinct synaptic and plasticity pathways associated with two closely related glutamatergic neuronal cell types that drive invertebrate locomotion.
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Affiliation(s)
- Nicole A. Aponte-Santiago
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, San Francisco, CA, United States
| | - J. Troy Littleton
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
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49
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Zhao K, Hong H, Zhao L, Huang S, Gao Y, Metwally E, Jiang Y, Sigrist SJ, Zhang YQ. Postsynaptic cAMP signalling regulates the antagonistic balance of Drosophila glutamate receptor subtypes. Development 2020; 147:226061. [PMID: 33234716 PMCID: PMC7758632 DOI: 10.1242/dev.191874] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 11/13/2020] [Indexed: 12/19/2022]
Abstract
The balance among different subtypes of glutamate receptors (GluRs) is crucial for synaptic function and plasticity at excitatory synapses. However, the mechanisms balancing synaptic GluR subtypes remain unclear. Herein, we show that the two subtypes of GluRs (A and B) expressed at Drosophila neuromuscular junction synapses mutually antagonize each other in terms of their relative synaptic levels and affect subsynaptic localization of each other, as shown by super-resolution microscopy. Upon temperature shift-induced neuromuscular junction plasticity, GluR subtype A increased but subtype B decreased with a timecourse of hours. Inhibition of the activity of GluR subtype A led to imbalance of GluR subtypes towards more GluRIIA. To gain a better understanding of the signalling pathways underlying the balance of GluR subtypes, we performed an RNA interference screen of candidate genes and found that postsynaptic-specific knockdown of dunce, which encodes cAMP phosphodiesterase, increased levels of GluR subtype A but decreased subtype B. Furthermore, bidirectional alterations of postsynaptic cAMP signalling resulted in the same antagonistic regulation of the two GluR subtypes. Our findings thus identify a direct role of postsynaptic cAMP signalling in control of the plasticity-related balance of GluRs. Summary: The antagonistic balance of GluR subtypes, which is associated with synaptic plasticity, is regulated by cAMP signalling in postsynaptic muscles of Drosophila NMJ synapses.
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Affiliation(s)
- Kai Zhao
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Huilin Hong
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Lu Zhao
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Sheng Huang
- Freie Universität Berlin, Institute for Biology/Genetics, Takustrasse 6, 14195 Berlin, Germany
| | - Ying Gao
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Elsayed Metwally
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yuqiang Jiang
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Stephan J Sigrist
- Freie Universität Berlin, Institute for Biology/Genetics, Takustrasse 6, 14195 Berlin, Germany.,NeuroCure, Charite, Chariteplatz 1, 10117 Berlin, Germany
| | - Yong Q Zhang
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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50
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The auxiliary glutamate receptor subunit dSol-1 promotes presynaptic neurotransmitter release and homeostatic potentiation. Proc Natl Acad Sci U S A 2020; 117:25830-25839. [PMID: 32973097 DOI: 10.1073/pnas.1915464117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Presynaptic glutamate receptors (GluRs) modulate neurotransmitter release and are physiological targets for regulation during various forms of plasticity. Although much is known about the auxiliary subunits associated with postsynaptic GluRs, far less is understood about presynaptic auxiliary GluR subunits and their functions. At the Drosophila neuromuscular junction, a presynaptic GluR, DKaiR1D, localizes near active zones and operates as an autoreceptor to tune baseline transmission and enhance presynaptic neurotransmitter release in response to diminished postsynaptic GluR functionality, a process referred to as presynaptic homeostatic potentiation (PHP). Here, we identify an auxiliary subunit that collaborates with DKaiR1D to promote these synaptic functions. This subunit, dSol-1, is the homolog of the Caenorhabditis elegans CUB (Complement C1r/C1s, Uegf, Bmp1) domain protein Sol-1. We find that dSol-1 functions in neurons to facilitate baseline neurotransmission and to enable PHP expression, properties shared with DKaiR1D Intriguingly, presynaptic overexpression of dSol-1 is sufficient to enhance neurotransmitter release through a DKaiR1D-dependent mechanism. Furthermore, dSol-1 is necessary to rapidly increase the abundance of DKaiR1D receptors near active zones during homeostatic signaling. Together with recent work showing the CUB domain protein Neto2 is necessary for the homeostatic modulation of postsynaptic GluRs in mammals, our data demonstrate that dSol-1 is required for the homeostatic regulation of presynaptic GluRs. Thus, we propose that CUB domain proteins are fundamental homeostatic modulators of GluRs on both sides of the synapse.
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