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Dresselhaus EC, Harris KP, Blanchette CR, Koles K, Del Signore SJ, Pescosolido MF, Ermanoska B, Rozencwaig M, Soslowsky RC, Parisi MJ, Stewart BA, Mosca TJ, Rodal AA. ESCRT disruption provides evidence against trans-synaptic signaling via extracellular vesicles. J Cell Biol 2024; 223:e202405025. [PMID: 38842573 DOI: 10.1083/jcb.202405025] [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: 05/05/2024] [Revised: 05/20/2024] [Accepted: 05/29/2024] [Indexed: 06/07/2024] Open
Abstract
Extracellular vesicles (EVs) are released by many cell types, including neurons, carrying cargoes involved in signaling and disease. It is unclear whether EVs promote intercellular signaling or serve primarily to dispose of unwanted materials. We show that loss of multivesicular endosome-generating endosomal sorting complex required for transport (ESCRT) machinery disrupts release of EV cargoes from Drosophila motor neurons. Surprisingly, ESCRT depletion does not affect the signaling activities of the EV cargo Synaptotagmin-4 (Syt4) and disrupts only some signaling activities of the EV cargo evenness interrupted (Evi). Thus, these cargoes may not require intercellular transfer via EVs, and instead may be conventionally secreted or function cell-autonomously in the neuron. We find that EVs are phagocytosed by glia and muscles, and that ESCRT disruption causes compensatory autophagy in presynaptic neurons, suggesting that EVs are one of several redundant mechanisms to remove cargoes from synapses. Our results suggest that synaptic EV release serves primarily as a proteostatic mechanism for certain cargoes.
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Affiliation(s)
| | - Kathryn P Harris
- Office of the Vice-Principal, Research and Innovation, University of Toronto Mississauga, Mississauga, Canada
| | | | - Kate Koles
- Department of Biology, Brandeis University, Waltham, MA, USA
| | | | | | | | - Mark Rozencwaig
- Department of Biology, Brandeis University, Waltham, MA, USA
| | | | - Michael J Parisi
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - Bryan A Stewart
- Department of Biology, University of Toronto Mississauga, Mississauga, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Timothy J Mosca
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - Avital A Rodal
- Department of Biology, Brandeis University, Waltham, MA, USA
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2
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Dresselhaus EC, Harris KP, Blanchette CR, Koles K, Del Signore SJ, Pescosolido MF, Ermanoska B, Rozencwaig M, Soslowsky RC, Parisi MJ, Stewart BA, Mosca TJ, Rodal AA. ESCRT disruption provides evidence against transsynaptic signaling functions for extracellular vesicles. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.04.22.537920. [PMID: 38746182 PMCID: PMC11092503 DOI: 10.1101/2023.04.22.537920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Extracellular vesicles (EVs) are released by many cell types including neurons, carrying cargoes involved in signaling and disease. It is unclear whether EVs promote intercellular signaling or serve primarily to dispose of unwanted materials. We show that loss of multivesicular endosome-generating ESCRT (endosomal sorting complex required for transport) machinery disrupts release of EV cargoes from Drosophila motor neurons. Surprisingly, ESCRT depletion does not affect the signaling activities of the EV cargo Synaptotagmin-4 (Syt4) and disrupts only some signaling activities of the EV cargo Evenness Interrupted (Evi). Thus, these cargoes may not require intercellular transfer via EVs, and instead may be conventionally secreted or function cell autonomously in the neuron. We find that EVs are phagocytosed by glia and muscles, and that ESCRT disruption causes compensatory autophagy in presynaptic neurons, suggesting that EVs are one of several redundant mechanisms to remove cargoes from synapses. Our results suggest that synaptic EV release serves primarily as a proteostatic mechanism for certain cargoes.
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Affiliation(s)
| | - Kathryn P. Harris
- Office of the Vice-Principal, Research and Innovation, University of Toronto, Mississauga, Mississauga, Canada
| | | | - Kate Koles
- Department of Biology, Brandeis University, Waltham, MA
| | | | | | | | | | | | - Michael J. Parisi
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA
| | - Bryan A. Stewart
- Department of Biology, University of Toronto Mississauga, Mississauga, Canada; Department of Cell and Systems Biology University of Toronto, Toronto, Canada
| | - Timothy J. Mosca
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA
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3
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Dominicci-Cotto C, Vazquez M, Marie B. The Wingless planar cell polarity pathway is essential for optimal activity-dependent synaptic plasticity. Front Synaptic Neurosci 2024; 16:1322771. [PMID: 38633293 PMCID: PMC11021733 DOI: 10.3389/fnsyn.2024.1322771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 03/18/2024] [Indexed: 04/19/2024] Open
Abstract
From fly to man, the Wingless (Wg)/Wnt signaling molecule is essential for both the stability and plasticity of the nervous system. The Drosophila neuromuscular junction (NMJ) has proven to be a useful system for deciphering the role of Wg in directing activity-dependent synaptic plasticity (ADSP), which, in the motoneuron, has been shown to be dependent on both the canonical and the noncanonical calcium Wg pathways. Here we show that the noncanonical planar cell polarity (PCP) pathway is an essential component of the Wg signaling system controlling plasticity at the motoneuron synapse. We present evidence that disturbing the PCP pathway leads to a perturbation in ADSP. We first show that a PCP-specific allele of disheveled (dsh) affects the de novo synaptic structures produced during ADSP. We then show that the Rho GTPases downstream of Dsh in the PCP pathway are also involved in regulating the morphological changes that take place after repeated stimulation. Finally, we show that Jun kinase is essential for this phenomenon, whereas we found no indication of the involvement of the transcription factor complex AP1 (Jun/Fos). This work shows the involvement of the neuronal PCP signaling pathway in supporting ADSP. Because we find that AP1 mutants can perform ADSP adequately, we hypothesize that, upon Wg activation, the Rho GTPases and Jun kinase are involved locally at the synapse, in instructing cytoskeletal dynamics responsible for the appearance of the morphological changes occurring during ADSP.
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Affiliation(s)
- Carihann Dominicci-Cotto
- Department of Anatomy and Neurobiology, Medical Sciences Campus, University of Puerto Rico, San Juan, PR, United States
- Institute of Neurobiology, Medical Sciences Campus, University of Puerto Rico, San Juan, PR, United States
| | - Mariam Vazquez
- Institute of Neurobiology, Medical Sciences Campus, University of Puerto Rico, San Juan, PR, United States
- Molecular Sciences Research Center, University of Puerto Rico, San Juan, PR, United States
| | - Bruno Marie
- Department of Anatomy and Neurobiology, Medical Sciences Campus, University of Puerto Rico, San Juan, PR, United States
- Institute of Neurobiology, Medical Sciences Campus, University of Puerto Rico, San Juan, PR, United States
- Molecular Sciences Research Center, University of Puerto Rico, San Juan, PR, United States
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4
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Mondal P, Bai P, Gomm A, Bakiasi G, Lin CJ, Wang Y, Choi SH, Tanzi RE, Wang C, Zhang C. Structure-Based Discovery of A Small Molecule Inhibitor of Histone Deacetylase 6 (HDAC6) that Significantly Reduces Alzheimer's Disease Neuropathology. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2304545. [PMID: 37990786 PMCID: PMC10767396 DOI: 10.1002/advs.202304545] [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] [Received: 07/05/2023] [Revised: 09/27/2023] [Indexed: 11/23/2023]
Abstract
Histone deacetylase 6 (HDAC6) is one of the key histone deacetylases (HDACs) that regulates various cellular functions including clearance of misfolded protein and immunological responses. Considerable evidence suggests that HDAC6 is closely related to amyloid and tau pathology, the two primary hallmarks of Alzheimer's disease (AD). It is still unclear whether HDAC6 expression changes with amyloid deposition in AD during disease progression or HDAC6 may be regulating amyloid phagocytosis or neuroinflammation or other neuropathological changes in AD. In this work, the pathological accumulation of HDAC6 in AD brains over age as well as the relationship of its regulatory activity - with amyloid pathogenesis and pathophysiological alterations is aimed to be enlightened using the newly developed HDAC6 inhibitor (HDAC6i) PB118 in microglia BV2 cell and 3D-AD human neural culture model. Results suggest that the structure-based rational design led to biologically compelling HDAC6i PB118 with multiple mechanisms that clear Aβ deposits by upregulating phagocytosis, improve tubulin/microtubule network by enhancing acetyl α-tubulin levels, regulate different cytokines and chemokines responsible for inflammation, and significantly reduce phospho-tau (p-tau) levels associated with AD. These findings indicate that HDAC6 plays key roles in the pathophysiology of AD and potentially serves as a suitable pharmacological target through chemical biology-based drug discovery in AD.
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Affiliation(s)
- Prasenjit Mondal
- Genetics and Aging Research Unit, McCance Center for Brain Health, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General HospitalHarvard Medical School BostonCharlestownBostonMA02114USA
| | - Ping Bai
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General HospitalHarvard Medical SchoolBuilding 149, CharlestownBostonMA02129USA
| | - Ashley Gomm
- Genetics and Aging Research Unit, McCance Center for Brain Health, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General HospitalHarvard Medical School BostonCharlestownBostonMA02114USA
| | - Grisilda Bakiasi
- Genetics and Aging Research Unit, McCance Center for Brain Health, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General HospitalHarvard Medical School BostonCharlestownBostonMA02114USA
| | - Chih‐Chung Jerry Lin
- Genetics and Aging Research Unit, McCance Center for Brain Health, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General HospitalHarvard Medical School BostonCharlestownBostonMA02114USA
| | - Yanli Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General HospitalHarvard Medical SchoolBuilding 149, CharlestownBostonMA02129USA
| | - Se Hoon Choi
- Genetics and Aging Research Unit, McCance Center for Brain Health, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General HospitalHarvard Medical School BostonCharlestownBostonMA02114USA
| | - Rudolph E. Tanzi
- Genetics and Aging Research Unit, McCance Center for Brain Health, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General HospitalHarvard Medical School BostonCharlestownBostonMA02114USA
| | - Changning Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General HospitalHarvard Medical SchoolBuilding 149, CharlestownBostonMA02129USA
| | - Can Zhang
- Genetics and Aging Research Unit, McCance Center for Brain Health, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General HospitalHarvard Medical School BostonCharlestownBostonMA02114USA
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Guangming G, Mei C, Qinfeng Y, Xiang G, Chenchen Z, Qingyuan S, Wei X, Junhua G. Neurexin and neuroligins jointly regulate synaptic degeneration at the Drosophila neuromuscular junction based on TEM studies. Front Cell Neurosci 2023; 17:1257347. [PMID: 38026694 PMCID: PMC10646337 DOI: 10.3389/fncel.2023.1257347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 09/12/2023] [Indexed: 12/01/2023] Open
Abstract
The Drosophila larval neuromuscular junction (NMJ) is a well-known model system and is often used to study synapse development. Here, we show synaptic degeneration at NMJ boutons, primarily based on transmission electron microscopy (TEM) studies. When degeneration starts, the subsynaptic reticulum (SSR) swells, retracts and folds inward, and the residual SSR then degenerates into a disordered, thin or linear membrane. The axon terminal begins to degenerate from the central region, and the T-bar detaches from the presynaptic membrane with clustered synaptic vesicles to accelerate large-scale degeneration. There are two degeneration modes for clear synaptic vesicles. In the first mode, synaptic vesicles without actin filaments degenerate on the membrane with ultrafine spots and collapse and disperse to form an irregular profile with dark ultrafine particles. In the second mode, clear synaptic vesicles with actin filaments degenerate into dense synaptic vesicles, form irregular dark clumps without a membrane, and collapse and disperse to form an irregular profile with dark ultrafine particles. Last, all residual membranes in NMJ boutons degenerate into a linear shape, and all the residual elements in axon terminals degenerate and eventually form a cluster of dark ultrafine particles. Swelling and retraction of the SSR occurs prior to degradation of the axon terminal, which degenerates faster and with more intensity than the SSR. NMJ bouton degeneration occurs under normal physiological conditions but is accelerated in Drosophila neurexin (dnrx) dnrx273, Drosophila neuroligin (dnlg) dnlg1 and dnlg4 mutants and dnrx83;dnlg3 and dnlg2;dnlg3 double mutants, which suggests that both neurexin and neuroligins play a vital role in preventing synaptic degeneration.
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Affiliation(s)
- Gan Guangming
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Chen Mei
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Yu Qinfeng
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Gao Xiang
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Zhang Chenchen
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Sheng Qingyuan
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Xie Wei
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
- The Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, Jiangsu, China
| | - Geng Junhua
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
- Shenzhen Research Institute of Southeast University, Shenzhen, Guangdong, China
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6
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Wang Y, Zhang R, Huang S, Valverde PTT, Lobb-Rabe M, Ashley J, Venkatasubramanian L, Carrillo RA. Glial Draper signaling triggers cross-neuron plasticity in bystander neurons after neuronal cell death in Drosophila. Nat Commun 2023; 14:4452. [PMID: 37488133 PMCID: PMC10366216 DOI: 10.1038/s41467-023-40142-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 07/07/2023] [Indexed: 07/26/2023] Open
Abstract
Neuronal cell death and subsequent brain dysfunction are hallmarks of aging and neurodegeneration, but how the nearby healthy neurons (bystanders) respond to the death of their neighbors is not fully understood. In the Drosophila larval neuromuscular system, bystander motor neurons can structurally and functionally compensate for the loss of their neighbors by increasing their terminal bouton number and activity. We term this compensation as cross-neuron plasticity, and in this study, we demonstrate that the Drosophila engulfment receptor, Draper, and the associated kinase, Shark, are required for cross-neuron plasticity. Overexpression of the Draper-I isoform boosts cross-neuron plasticity, implying that the strength of plasticity correlates with Draper signaling. In addition, we find that functional cross-neuron plasticity can be induced at different developmental stages. Our work uncovers a role for Draper signaling in cross-neuron plasticity and provides insights into how healthy bystander neurons respond to the loss of their neighboring neurons.
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Affiliation(s)
- Yupu Wang
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA.
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA.
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, 20147, USA.
| | - Ruiling Zhang
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Sihao Huang
- Program in Biochemistry and Molecular Biophysics, University of Chicago, Chicago, IL, 60637, USA
| | - Parisa Tajalli Tehrani Valverde
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Meike Lobb-Rabe
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA
- Program in Cell and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - James Ashley
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA
| | | | - Robert A Carrillo
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA.
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA.
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, IL, 60637, USA.
- Program in Cell and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA.
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7
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Ji H, Wang B, Shen Y, Labib D, Lei J, Chen X, Sapar M, Boulanger A, Dura JM, Han C. The Drosophila chemokine-like Orion bridges phosphatidylserine and Draper in phagocytosis of neurons. Proc Natl Acad Sci U S A 2023; 120:e2303392120. [PMID: 37276397 PMCID: PMC10268242 DOI: 10.1073/pnas.2303392120] [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: 02/28/2023] [Accepted: 04/10/2023] [Indexed: 06/07/2023] Open
Abstract
Phagocytic clearance of degenerating neurons is triggered by "eat-me" signals exposed on the neuronal surface. The conserved neuronal eat-me signal phosphatidylserine (PS) and the engulfment receptor Draper (Drpr) mediate phagocytosis of degenerating neurons in Drosophila. However, how PS is recognized by Drpr-expressing phagocytes in vivo remains poorly understood. Using multiple models of dendrite degeneration, we show that the Drosophila chemokine-like protein Orion can bind to PS and is responsible for detecting PS exposure on neurons; it is supplied cell-non-autonomously to coat PS-exposing dendrites and to mediate interactions between PS and Drpr, thus enabling phagocytosis. As a result, the accumulation of Orion on neurons and on phagocytes produces opposite outcomes by potentiating and suppressing phagocytosis, respectively. Moreover, the Orion dosage is a key determinant of the sensitivity of phagocytes to PS exposed on neurons. Lastly, mutagenesis analyses show that the sequence motifs shared between Orion and human immunomodulatory proteins are important for Orion function. Thus, our results uncover a missing link in PS-mediated phagocytosis in Drosophila and imply conserved mechanisms of phagocytosis of neurons.
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Affiliation(s)
- Hui Ji
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Bei Wang
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Yifan Shen
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - David Labib
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Joyce Lei
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Xinchen Chen
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Maria Sapar
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Ana Boulanger
- Institute of Human Genetics (IGH), Univ Montpellier, CNRS, Montpellier34090, France
| | - Jean-Maurice Dura
- Institute of Human Genetics (IGH), Univ Montpellier, CNRS, Montpellier34090, France
| | - Chun Han
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
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8
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Fernandes AR, Martins JP, Gomes ER, Mendes CS, Teodoro RO. Drosophila motor neuron boutons remodel through membrane blebbing coupled with muscle contraction. Nat Commun 2023; 14:3352. [PMID: 37291089 PMCID: PMC10250368 DOI: 10.1038/s41467-023-38421-9] [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: 03/30/2021] [Accepted: 04/26/2023] [Indexed: 06/10/2023] Open
Abstract
Wired neurons form new presynaptic boutons in response to increased synaptic activity, however the mechanism(s) by which this occurs remains uncertain. Drosophila motor neurons (MNs) have clearly discernible boutons that display robust structural plasticity, being therefore an ideal system in which to study activity-dependent bouton genesis. Here, we show that in response to depolarization and in resting conditions, MNs form new boutons by membrane blebbing, a pressure-driven mechanism that occurs in 3-D cell migration, but to our knowledge not previously described to occur in neurons. Accordingly, F-actin is decreased in boutons during outgrowth, and non-muscle myosin-II is dynamically recruited to newly formed boutons. Furthermore, muscle contraction plays a mechanical role, which we hypothesize promotes bouton addition by increasing MN confinement. Overall, we identified a mechanism by which established circuits form new boutons allowing their structural expansion and plasticity, using trans-synaptic physical forces as the main driving force.
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Affiliation(s)
- Andreia R Fernandes
- iNOVA4Health, NOVA Medical School|Faculdade de Ciências Médicas, NMS|FCM, Universidade Nova de Lisboa, Lisboa, Portugal
| | - João P Martins
- iNOVA4Health, NOVA Medical School|Faculdade de Ciências Médicas, NMS|FCM, Universidade Nova de Lisboa, Lisboa, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisboa, Portugal
| | - Edgar R Gomes
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisboa, Portugal
| | - César S Mendes
- iNOVA4Health, NOVA Medical School|Faculdade de Ciências Médicas, NMS|FCM, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Rita O Teodoro
- iNOVA4Health, NOVA Medical School|Faculdade de Ciências Médicas, NMS|FCM, Universidade Nova de Lisboa, Lisboa, Portugal.
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9
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Wang Y, Zhang R, Huang S, Valverde PTT, Lobb-Rabe M, Ashley J, Venkatasubramanian L, Carrillo RA. Glial Draper signaling triggers cross-neuron plasticity in bystander neurons after neuronal cell death. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.09.536190. [PMID: 37090512 PMCID: PMC10120647 DOI: 10.1101/2023.04.09.536190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Neuronal cell death and subsequent brain dysfunction are hallmarks of aging and neurodegeneration, but how the nearby healthy neurons (bystanders) respond to the cell death of their neighbors is not fully understood. In the Drosophila larval neuromuscular system, bystander motor neurons can structurally and functionally compensate for the loss of their neighbors by increasing their axon terminal size and activity. We termed this compensation as cross-neuron plasticity, and in this study, we demonstrated that the Drosophila engulfment receptor, Draper, and the associated kinase, Shark, are required in glial cells. Surprisingly, overexpression of the Draper-I isoform boosts cross-neuron plasticity, implying that the strength of plasticity correlates with Draper signaling. Synaptic plasticity normally declines as animals age, but in our system, functional cross-neuron plasticity can be induced at different time points, whereas structural cross-neuron plasticity can only be induced at early stages. Our work uncovers a novel role for glial Draper signaling in cross-neuron plasticity that may enhance nervous system function during neurodegeneration and provides insights into how healthy bystander neurons respond to the loss of their neighboring neurons.
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10
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Lin WY, Liu CH, Cheng J, Liu HP. Alterations of RNA-binding protein found in neurons in Drosophila neurons and glia influence synaptic transmission and lifespan. Front Mol Neurosci 2022; 15:1006455. [DOI: 10.3389/fnmol.2022.1006455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 10/24/2022] [Indexed: 11/13/2022] Open
Abstract
The found in neurons (fne), a paralog of the RNA-binding protein ELAV gene family in Drosophila, is required for post-transcriptional regulation of neuronal development and differentiation. Previous explorations into the functions of the FNE protein have been limited to neurons. The function of fne in Drosophila glia remains unclear. We induced the knockdown or overexpression of fne in Drosophila neurons and glia to determine how fne affects different types of behaviors, neuronal transmission and the lifespan. Our data indicate that changes in fne expression impair associative learning, thermal nociception, and phototransduction. Examination of synaptic transmission at presynaptic and postsynaptic terminals of the larval neuromuscular junction (NMJ) revealed that loss of fne in motor neurons and glia significantly decreased excitatory junction currents (EJCs) and quantal content, while flies with glial fne knockdown facilitated short-term synaptic plasticity. In muscle cells, overexpression of fne reduced both EJC and quantal content and increased short-term synaptic facilitation. In both genders, the lifespan could be extended by the knockdown of fne in neurons and glia; the overexpression of fne shortened the lifespan. Our results demonstrate that disturbances of fne in neurons and glia influence the function of the Drosophila nervous system. Further explorations into the physiological and molecular mechanisms underlying neuronal and glial fne and elucidation of how fne affects neuronal activity may clarify certain brain functions.
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11
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Delta/Notch signaling in glia maintains motor nerve barrier function and synaptic transmission by controlling matrix metalloproteinase expression. Proc Natl Acad Sci U S A 2022; 119:e2110097119. [PMID: 35969789 PMCID: PMC9407389 DOI: 10.1073/pnas.2110097119] [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] [Indexed: 11/18/2022] Open
Abstract
We have made a surprising discovery linking Delta/Notch signaling in subperineurial glia (SPG) to the regulation of nerve ensheathment and neurotransmitter release at the Drosophila neuromuscular junction (NMJ). SPG, the counterpart of the endothelial layer in the vertebrate blood–brain barrier, form the key cellular layer that is critical for axonal ensheathment and the blood–brain barrier in Drosophila. Our findings demonstrate that Delta/Notch signaling exerts a constitutive negative inhibition on JNK signaling in SPG, thereby limiting the expression of Mmp1, a matrix metalloproteinase. SPG-specific and temporally regulated knockdown of Delta leads to breakdown of barrier function and compromises neurotransmitter release at the NMJ. Our results provide a mechanistic insight into the biology of barrier function and glia–neuron interactions. While the role of barrier function in establishing a protective, nutrient-rich, and ionically balanced environment for neurons has been appreciated for some time, little is known about how signaling cues originating in barrier-forming cells participate in maintaining barrier function and influence synaptic activity. We have identified Delta/Notch signaling in subperineurial glia (SPG), a crucial glial type for Drosophila motor axon ensheathment and the blood–brain barrier, to be essential for controlling the expression of matrix metalloproteinase 1 (Mmp1), a major regulator of the extracellular matrix (ECM). Our genetic analysis indicates that Delta/Notch signaling in SPG exerts an inhibitory control on Mmp1 expression. In the absence of this inhibition, abnormally enhanced Mmp1 activity disrupts septate junctions and glial ensheathment of peripheral motor nerves, compromising neurotransmitter release at the neuromuscular junction (NMJ). Temporally controlled and cell type–specific transgenic analysis shows that Delta/Notch signaling inhibits transcription of Mmp1 by inhibiting c-Jun N-terminal kinase (JNK) signaling in SPG. Our results provide a mechanistic insight into the regulation of neuronal health and function via glial-initiated signaling and open a framework for understanding the complex relationship between ECM regulation and the maintenance of barrier function.
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12
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Restrepo LJ, DePew AT, Moese ER, Tymanskyj SR, Parisi MJ, Aimino MA, Duhart JC, Fei H, Mosca TJ. γ-secretase promotes Drosophila postsynaptic development through the cleavage of a Wnt receptor. Dev Cell 2022; 57:1643-1660.e7. [PMID: 35654038 DOI: 10.1016/j.devcel.2022.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 04/06/2022] [Accepted: 05/10/2022] [Indexed: 12/27/2022]
Abstract
Developing synapses mature through the recruitment of specific proteins that stabilize presynaptic and postsynaptic structure and function. Wnt ligands signaling via Frizzled (Fz) receptors play many crucial roles in neuronal and synaptic development, but whether and how Wnt and Fz influence synaptic maturation is incompletely understood. Here, we show that Fz2 receptor cleavage via the γ-secretase complex is required for postsynaptic development and maturation. In the absence of γ-secretase, Drosophila neuromuscular synapses fail to recruit postsynaptic scaffolding and cytoskeletal proteins, leading to behavioral deficits. Introducing presenilin mutations linked to familial early-onset Alzheimer's disease into flies leads to synaptic maturation phenotypes that are identical to those seen in null alleles. This conserved role for γ-secretase in synaptic maturation and postsynaptic development highlights the importance of Fz2 cleavage and suggests that receptor processing by proteins linked to neurodegeneration may be a shared mechanism with aspects of synaptic development.
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Affiliation(s)
- Lucas J Restrepo
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA
| | - Alison T DePew
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA
| | - Elizabeth R Moese
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA
| | - Stephen R Tymanskyj
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA
| | - Michael J Parisi
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA
| | - Michael A Aimino
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA
| | - Juan Carlos Duhart
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA
| | - Hong Fei
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA
| | - Timothy J Mosca
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA.
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13
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Blanchette CR, Scalera AL, Harris KP, Zhao Z, Dresselhaus EC, Koles K, Yeh A, Apiki JK, Stewart BA, Rodal AA. Local regulation of extracellular vesicle traffic by the synaptic endocytic machinery. J Cell Biol 2022; 221:e202112094. [PMID: 35320349 PMCID: PMC8952828 DOI: 10.1083/jcb.202112094] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 02/14/2022] [Accepted: 02/28/2022] [Indexed: 02/01/2023] Open
Abstract
Neuronal extracellular vesicles (EVs) are locally released from presynaptic terminals, carrying cargoes critical for intercellular signaling and disease. EVs are derived from endosomes, but it is unknown how these cargoes are directed to the EV pathway rather than for conventional endolysosomal degradation. Here, we find that endocytic machinery plays an unexpected role in maintaining a release-competent pool of EV cargoes at synapses. Endocytic mutants, including nervous wreck (nwk), shibire/dynamin, and AP-2, unexpectedly exhibit local presynaptic depletion specifically of EV cargoes. Accordingly, nwk mutants phenocopy synaptic plasticity defects associated with loss of the EV cargo synaptotagmin-4 (Syt4) and suppress lethality upon overexpression of the EV cargo amyloid precursor protein (APP). These EV defects are genetically separable from canonical endocytic functions in synaptic vesicle recycling and synaptic growth. Endocytic machinery opposes the endosomal retromer complex to regulate EV cargo levels and acts upstream of synaptic cargo removal by retrograde axonal transport. Our data suggest a novel molecular mechanism that locally promotes cargo loading into synaptic EVs.
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Affiliation(s)
| | | | - Kathryn P. Harris
- Department of Biology, University of Toronto Mississauga, Mississauga, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Zechuan Zhao
- Department of Biology, Brandeis University, Waltham, MA
| | | | - Kate Koles
- Department of Biology, Brandeis University, Waltham, MA
| | - Anna Yeh
- Department of Biology, Brandeis University, Waltham, MA
| | | | - Bryan A. Stewart
- Department of Biology, University of Toronto Mississauga, Mississauga, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
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14
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Rochat C, Bernard-Marissal N, Källstig E, Pradervand S, Perrin FE, Aebischer P, Raoul C, Schneider BL. Astrocyte-targeting RNA interference against mutated superoxide dismutase 1 induces motoneuron plasticity and protects fast-fatigable motor units in a mouse model of amyotrophic lateral sclerosis. Glia 2022; 70:842-857. [PMID: 34978340 PMCID: PMC9303637 DOI: 10.1002/glia.24140] [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: 09/23/2021] [Revised: 12/19/2021] [Accepted: 12/22/2021] [Indexed: 11/22/2022]
Abstract
In amyotrophic lateral sclerosis (ALS) caused by SOD1 gene mutations, both cell‐autonomous and noncell‐autonomous mechanisms lead to the selective degeneration of motoneurons (MN). Here, we evaluate the therapeutic potential of gene therapy targeting mutated SOD1 in mature astrocytes using mice expressing the mutated SOD1G93A protein. An AAV‐gfaABC1D vector encoding an artificial microRNA is used to deliver RNA interference against mutated SOD1 selectively in astrocytes. The treatment leads to the progressive rescue of neuromuscular junction occupancy, to the recovery of the compound muscle action potential in the gastrocnemius muscle, and significantly improves neuromuscular function. In the spinal cord, gene therapy targeting astrocytes protects a small pool of the most vulnerable fast‐fatigable MN until disease end stage. In the gastrocnemius muscle of the treated SOD1G93A mice, the fast‐twitch type IIB muscle fibers are preserved from atrophy. Axon collateral sprouting is observed together with muscle fiber type grouping indicative of denervation/reinnervation events. The transcriptome profiling of spinal cord MN shows changes in the expression levels of factors regulating the dynamics of microtubules. Gene therapy delivering RNA interference against mutated SOD1 in astrocytes protects fast‐fatigable motor units and thereby improves neuromuscular function in ALS mice.
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Affiliation(s)
- Cylia Rochat
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Brain Mind Institute, Lausanne
| | - Nathalie Bernard-Marissal
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Brain Mind Institute, Lausanne.,INSERM, MMG, Aix-Marseille University, Marseille, France
| | - Emma Källstig
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Brain Mind Institute, Lausanne.,Bertarelli Platform for Gene Therapy, Ecole Polytechnique Fédérale de Lausanne (EPFL), Geneva
| | - Sylvain Pradervand
- Genomic Technologies Facility, University of Lausanne, Lausanne, Switzerland
| | | | - Patrick Aebischer
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Brain Mind Institute, Lausanne
| | - Cédric Raoul
- INM, Université Montpellier, INSERM, Montpellier, France
| | - Bernard L Schneider
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Brain Mind Institute, Lausanne.,Bertarelli Platform for Gene Therapy, Ecole Polytechnique Fédérale de Lausanne (EPFL), Geneva
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15
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Faust TE, Gunner G, Schafer DP. Mechanisms governing activity-dependent synaptic pruning in the developing mammalian CNS. Nat Rev Neurosci 2021; 22:657-673. [PMID: 34545240 PMCID: PMC8541743 DOI: 10.1038/s41583-021-00507-y] [Citation(s) in RCA: 114] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2021] [Indexed: 02/08/2023]
Abstract
Almost 60 years have passed since the initial discovery by Hubel and Wiesel that changes in neuronal activity can elicit developmental rewiring of the central nervous system (CNS). Over this period, we have gained a more comprehensive picture of how both spontaneous neural activity and sensory experience-induced changes in neuronal activity guide CNS circuit development. Here we review activity-dependent synaptic pruning in the mammalian CNS, which we define as the removal of a subset of synapses, while others are maintained, in response to changes in neural activity in the developing nervous system. We discuss the mounting evidence that immune and cell-death molecules are important mechanistic links by which changes in neural activity guide the pruning of specific synapses, emphasizing the role of glial cells in this process. Finally, we discuss how these developmental pruning programmes may go awry in neurodevelopmental disorders of the human CNS, focusing on autism spectrum disorder and schizophrenia. Together, our aim is to give an overview of how the field of activity-dependent pruning research has evolved, led to exciting new questions and guided the identification of new, therapeutically relevant mechanisms that result in aberrant circuit development in neurodevelopmental disorders.
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Affiliation(s)
- Travis E Faust
- Department of Neurobiology, Brudnick Neuropsychiatric Research Institute, University of Massachusetts Medical School, Worcester, MA, USA
| | - Georgia Gunner
- Department of Neurobiology, Brudnick Neuropsychiatric Research Institute, University of Massachusetts Medical School, Worcester, MA, USA
| | - Dorothy P Schafer
- Department of Neurobiology, Brudnick Neuropsychiatric Research Institute, University of Massachusetts Medical School, Worcester, MA, USA.
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16
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Woo E, Sansing LH, Arnsten AFT, Datta D. Chronic Stress Weakens Connectivity in the Prefrontal Cortex: Architectural and Molecular Changes. CHRONIC STRESS 2021; 5:24705470211029254. [PMID: 34485797 PMCID: PMC8408896 DOI: 10.1177/24705470211029254] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 06/14/2021] [Indexed: 12/26/2022]
Abstract
Chronic exposure to uncontrollable stress causes loss of spines and dendrites in the prefrontal cortex (PFC), a recently evolved brain region that provides top-down regulation of thought, action, and emotion. PFC neurons generate top-down goals through recurrent excitatory connections on spines. This persistent firing is the foundation for higher cognition, including working memory, and abstract thought. However, exposure to acute uncontrollable stress drives high levels of catecholamine release in the PFC, which activates feedforward calcium-cAMP signaling pathways to open nearby potassium channels, rapidly weakening synaptic connectivity to reduce persistent firing. Chronic stress exposures can further exacerbate these signaling events leading to loss of spines and resulting in marked cognitive impairment. In this review, we discuss how stress signaling mechanisms can lead to spine loss, including changes to BDNF-mTORC1 signaling, calcium homeostasis, actin dynamics, and mitochondrial actions that engage glial removal of spines through inflammatory signaling. Stress signaling events may be amplified in PFC spines due to cAMP magnification of internal calcium release. As PFC dendritic spine loss is a feature of many cognitive disorders, understanding how stress affects the structure and function of the PFC will help to inform strategies for treatment and prevention.
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Affiliation(s)
- Elizabeth Woo
- Department of Neuroscience, Yale Medical School, New Haven, CT, USA.,Department of Neurology, Yale Medical School, New Haven, CT, USA
| | - Lauren H Sansing
- Department of Neurology, Yale Medical School, New Haven, CT, USA
| | - Amy F T Arnsten
- Department of Neuroscience, Yale Medical School, New Haven, CT, USA
| | - Dibyadeep Datta
- Department of Neuroscience, Yale Medical School, New Haven, CT, USA
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17
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Prakash P, Jethava KP, Korte N, Izquierdo P, Favuzzi E, Rose IVL, Guttenplan KA, Manchanda P, Dutta S, Rochet JC, Fishell G, Liddelow SA, Attwell D, Chopra G. Monitoring phagocytic uptake of amyloid β into glial cell lysosomes in real time. Chem Sci 2021; 12:10901-10918. [PMID: 34476070 PMCID: PMC8372545 DOI: 10.1039/d1sc03486c] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Accepted: 07/07/2021] [Indexed: 12/30/2022] Open
Abstract
Phagocytosis by glial cells is essential to regulate brain function during health and disease. Therapies for Alzheimer's disease (AD) have primarily focused on targeting antibodies to amyloid β (Aβ) or inhibitng enzymes that make it, and while removal of Aβ by phagocytosis is protective early in AD it remains poorly understood. Impaired phagocytic function of glial cells during later stages of AD likely contributes to worsened disease outcome, but the underlying mechanisms of how this occurs remain unknown. We have developed a human Aβ1-42 analogue (AβpH) that exhibits green fluorescence upon internalization into the acidic organelles of cells but is non-fluorescent at physiological pH. This allowed us to image, for the first time, glial uptake of AβpH in real time in live animals. We find that microglia phagocytose more AβpH than astrocytes in culture, in brain slices and in vivo. AβpH can be used to investigate the phagocytic mechanisms responsible for removing Aβ from the extracellular space, and thus could become a useful tool to study Aβ clearance at different stages of AD.
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Affiliation(s)
- Priya Prakash
- Department of Chemistry, Purdue University West Lafayette IN 47907 USA
| | - Krupal P Jethava
- Department of Chemistry, Purdue University West Lafayette IN 47907 USA
| | - Nils Korte
- Department of Neuroscience, Physiology and Pharmacology, University College London London WC1E 6BT UK
| | - Pablo Izquierdo
- Department of Neuroscience, Physiology and Pharmacology, University College London London WC1E 6BT UK
| | - Emilia Favuzzi
- Department of Neurobiology, Harvard Medical School 220 Longwood Avenue Boston MA 02115 USA
- Stanley Center at the Broad 75 Ames Street Cambridge MA 02142 USA
| | - Indigo V L Rose
- Neuroscience Institute, NYU Grossman School of Medicine New York NY 10016 USA
| | | | - Palak Manchanda
- Department of Chemistry, Purdue University West Lafayette IN 47907 USA
| | - Sayan Dutta
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University West Lafayette IN 47907 USA
| | - Jean-Christophe Rochet
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University West Lafayette IN 47907 USA
- Purdue Institute for Integrative Neuroscience, Purdue University West Lafayette IN 47907 USA
| | - Gord Fishell
- Department of Neurobiology, Harvard Medical School 220 Longwood Avenue Boston MA 02115 USA
- Stanley Center at the Broad 75 Ames Street Cambridge MA 02142 USA
| | - Shane A Liddelow
- Neuroscience Institute, NYU Grossman School of Medicine New York NY 10016 USA
- Department of Neuroscience & Physiology, NYU Grossman School of Medicine New York NY 10016 USA
- Department of Ophthalmology, NYU Grossman School of Medicine New York NY 10016 USA
| | - David Attwell
- Department of Neuroscience, Physiology and Pharmacology, University College London London WC1E 6BT UK
| | - Gaurav Chopra
- Department of Chemistry, Purdue University West Lafayette IN 47907 USA
- Purdue Institute for Integrative Neuroscience, Purdue University West Lafayette IN 47907 USA
- Purdue Institute for Drug Discovery 720 Clinic Drive West Lafayette IN 47907 USA
- Purdue Center for Cancer Research, Purdue University West Lafayette IN 47907 USA
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University West Lafayette IN 47907 USA
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18
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Petrignani B, Rommelaere S, Hakim-Mishnaevski K, Masson F, Ramond E, Hilu-Dadia R, Poidevin M, Kondo S, Kurant E, Lemaitre B. A secreted factor NimrodB4 promotes the elimination of apoptotic corpses by phagocytes in Drosophila. EMBO Rep 2021; 22:e52262. [PMID: 34370384 PMCID: PMC8419693 DOI: 10.15252/embr.202052262] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 06/22/2021] [Accepted: 06/30/2021] [Indexed: 01/07/2023] Open
Abstract
Programmed cell death plays a fundamental role in development and tissue homeostasis. Professional and non‐professional phagocytes achieve the proper recognition, uptake, and degradation of apoptotic cells, a process called efferocytosis. Failure in efferocytosis leads to autoimmune and neurodegenerative diseases. In Drosophila, two transmembrane proteins of the Nimrod family, Draper and SIMU, mediate the recognition and internalization of apoptotic corpses. Beyond this early step, little is known about how apoptotic cell degradation is regulated. Here, we study the function of a secreted member of the Nimrod family, NimB4, and reveal its crucial role in the clearance of apoptotic cells. We show that NimB4 is expressed by macrophages and glial cells, the two main types of phagocytes in Drosophila. Similar to draper mutants, NimB4 mutants accumulate apoptotic corpses during embryogenesis and in the larval brain. Our study points to the role of NimB4 in phagosome maturation, more specifically in the fusion between the phagosome and lysosomes. We propose that similar to bridging molecules, NimB4 binds to apoptotic corpses to engage a phagosome maturation program dedicated to efferocytosis.
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Affiliation(s)
- Bianca Petrignani
- Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Samuel Rommelaere
- Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Ketty Hakim-Mishnaevski
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Florent Masson
- Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Elodie Ramond
- Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Reut Hilu-Dadia
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | | | - Shu Kondo
- Invertebrate Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, Mishima, Japan
| | - Estee Kurant
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Bruno Lemaitre
- Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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19
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Walsh RB, Dresselhaus EC, Becalska AN, Zunitch MJ, Blanchette CR, Scalera AL, Lemos T, Lee SM, Apiki J, Wang S, Isaac B, Yeh A, Koles K, Rodal AA. Opposing functions for retromer and Rab11 in extracellular vesicle traffic at presynaptic terminals. J Cell Biol 2021; 220:212178. [PMID: 34019080 PMCID: PMC8144913 DOI: 10.1083/jcb.202012034] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 03/15/2021] [Accepted: 04/29/2021] [Indexed: 12/18/2022] Open
Abstract
Neuronal extracellular vesicles (EVs) play important roles in intercellular communication and pathogenic protein propagation in neurological disease. However, it remains unclear how cargoes are selectively packaged into neuronal EVs. Here, we show that loss of the endosomal retromer complex leads to accumulation of EV cargoes including amyloid precursor protein (APP), synaptotagmin-4 (Syt4), and neuroglian (Nrg) at Drosophila motor neuron presynaptic terminals, resulting in increased release of these cargoes in EVs. By systematically exploring known retromer-dependent trafficking mechanisms, we show that EV regulation is separable from several previously identified roles of neuronal retromer. Conversely, mutations in rab11 and rab4, regulators of endosome-plasma membrane recycling, cause reduced EV cargo levels, and rab11 suppresses cargo accumulation in retromer mutants. Thus, EV traffic reflects a balance between Rab4/Rab11 recycling and retromer-dependent removal from EV precursor compartments. Our data shed light on previous studies implicating Rab11 and retromer in competing pathways in Alzheimer's disease, and suggest that misregulated EV traffic may be an underlying defect.
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Affiliation(s)
- Rylie B Walsh
- Department of Biology, Brandeis University, Waltham, MA
| | | | | | | | | | - Amy L Scalera
- Department of Biology, Brandeis University, Waltham, MA
| | - Tania Lemos
- Department of Biology, Brandeis University, Waltham, MA
| | - So Min Lee
- Department of Biology, Brandeis University, Waltham, MA
| | - Julia Apiki
- Department of Biology, Brandeis University, Waltham, MA
| | - ShiYu Wang
- Department of Biology, Brandeis University, Waltham, MA
| | - Berith Isaac
- Department of Biology, Brandeis University, Waltham, MA
| | - Anna Yeh
- Department of Biology, Brandeis University, Waltham, MA
| | - Kate Koles
- Department of Biology, Brandeis University, Waltham, MA
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20
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Dason JS, Sokolowski MB. A cGMP-dependent protein kinase, encoded by the Drosophila foraging gene, regulates neurotransmission through changes in synaptic structure and function. J Neurogenet 2021; 35:213-220. [PMID: 33998378 DOI: 10.1080/01677063.2021.1905639] [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] [Indexed: 10/21/2022]
Abstract
A cGMP-dependent protein kinase (PKG) encoded by the Drosophila foraging (for) gene regulates both synaptic structure (nerve terminal growth) and function (neurotransmission) through independent mechanisms at the Drosophila larval neuromuscular junction (nmj). Glial for is known to restrict nerve terminal growth, whereas presynaptic for inhibits synaptic vesicle (SV) exocytosis during low frequency stimulation. Presynaptic for also facilitates SV endocytosis during high frequency stimulation. for's effects on neurotransmission can occur independent of any changes in nerve terminal growth. However, it remains unclear if for's effects on neurotransmission affect nerve terminal growth. Furthermore, it's possible that for's effects on synaptic structure contribute to changes in neurotransmission. In the present study, we examined these questions using RNA interference to selectively knockdown for in presynaptic neurons or glia at the Drosophila larval nmj. Consistent with our previous findings, presynaptic knockdown of for impaired SV endocytosis, whereas knockdown of glial for had no effect on SV endocytosis. Surprisingly, we found that knockdown of either presynaptic or glial for increased neurotransmitter release in response to low frequency stimulation. Knockdown of presynaptic for did not affect nerve terminal growth, demonstrating that for's effects on neurotransmission does not alter nerve terminal growth. In contrast, knockdown of glial for enhanced nerve terminal growth. This enhanced nerve terminal growth was likely the cause of the enhanced neurotransmitter release seen following knockdown of glial for. Overall, we show that for can affect neurotransmitter release by regulating both synaptic structure and function.
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Affiliation(s)
- Jeffrey S Dason
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada.,Department of Biomedical Sciences, University of Windsor, Windsor, Canada
| | - Marla B Sokolowski
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada.,Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Canada.,Child and Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Canada
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21
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Nazareth L, St John J, Murtaza M, Ekberg J. Phagocytosis by Peripheral Glia: Importance for Nervous System Functions and Implications in Injury and Disease. Front Cell Dev Biol 2021; 9:660259. [PMID: 33898462 PMCID: PMC8060502 DOI: 10.3389/fcell.2021.660259] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 03/17/2021] [Indexed: 12/30/2022] Open
Abstract
The central nervous system (CNS) has very limited capacity to regenerate after traumatic injury or disease. In contrast, the peripheral nervous system (PNS) has far greater capacity for regeneration. This difference can be partly attributed to variances in glial-mediated functions, such as axon guidance, structural support, secretion of growth factors and phagocytic activity. Due to their growth-promoting characteristic, transplantation of PNS glia has been trialed for neural repair. After peripheral nerve injuries, Schwann cells (SCs, the main PNS glia) phagocytose myelin debris and attract macrophages to the injury site to aid in debris clearance. One peripheral nerve, the olfactory nerve, is unique in that it continuously regenerates throughout life. The olfactory nerve glia, olfactory ensheathing cells (OECs), are the primary phagocytes within this nerve, continuously clearing axonal debris arising from the normal regeneration of the nerve and after injury. In contrast to SCs, OECs do not appear to attract macrophages. SCs and OECs also respond to and phagocytose bacteria, a function likely critical for tackling microbial invasion of the CNS via peripheral nerves. However, phagocytosis is not always effective; inflammation, aging and/or genetic factors may contribute to compromised phagocytic activity. Here, we highlight the diverse roles of SCs and OECs with the focus on their phagocytic activity under physiological and pathological conditions. We also explore why understanding the contribution of peripheral glia phagocytosis may provide us with translational strategies for achieving axonal regeneration of the injured nervous system and potentially for the treatment of certain neurological diseases.
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Affiliation(s)
- Lynn Nazareth
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia
| | - James St John
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Mariyam Murtaza
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Jenny Ekberg
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
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22
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Böhme MA, McCarthy AW, Blaum N, Berezeckaja M, Ponimaskine K, Schwefel D, Walter AM. Glial Synaptobrevin mediates peripheral nerve insulation, neural metabolic supply, and is required for motor function. Glia 2021; 69:1897-1915. [PMID: 33811396 DOI: 10.1002/glia.24000] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 03/12/2021] [Accepted: 03/17/2021] [Indexed: 01/10/2023]
Abstract
Peripheral nerves contain sensory and motor neuron axons coated by glial cells whose interplay ensures function, but molecular details are lacking. SNARE-proteins mediate the exchange and secretion of cargo by fusing vesicles with target organelles, but how glial SNAREs contribute to peripheral nerve function is largely unknown. We, here, identify non-neuronal Synaptobrevin (Syb) as the essential vesicular SNARE in Drosophila peripheral glia to insulate and metabolically supply neurons. We show that tetanus neurotoxin light chain (TeNT-LC), which potently inhibits SNARE-mediated exocytosis from neurons, also impairs peripheral nerve function when selectively expressed in glia, causing nerve disintegration, defective axonal transport, tetanic muscle hyperactivity, impaired locomotion, and lethality. While TeNT-LC disrupts neural function by cleaving neuronal Synaptobrevin (nSyb), it targets non-neuronal Synaptobrevin (Syb) in glia, which it cleaves at low rates: Glial knockdown of Syb (but not nSyb) phenocopied glial TeNT-LC expression whose effects were reverted by a TeNT-LC-insensitive Syb mutant. We link Syb-necessity to two distinct glial subtypes: Impairing Syb function in subperineurial glia disrupted nerve morphology, axonal transport, and locomotion, likely, because nerve-isolating septate junctions (SJs) could not form as essential SJ components (like the cell adhesion protein Neurexin-IV) were mistargeted. Interference with Syb in axon-encircling wrapping glia left nerve morphology and locomotion intact but impaired axonal transport, likely because neural metabolic supply was disrupted due to the mistargeting of metabolite shuffling monocarboxylate transporters. Our study identifies crucial roles of Syb in various glial subtypes to ensure glial-glial and glial-neural interplay needed for proper nerve function, animal motility, and survival.
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Affiliation(s)
- Mathias A Böhme
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), FMP im CharitéCrossOver, Berlin, Germany.,Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anthony W McCarthy
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), FMP im CharitéCrossOver, Berlin, Germany
| | - Natalie Blaum
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), FMP im CharitéCrossOver, Berlin, Germany
| | - Monika Berezeckaja
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), FMP im CharitéCrossOver, Berlin, Germany
| | - Kristina Ponimaskine
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), FMP im CharitéCrossOver, Berlin, Germany
| | - David Schwefel
- Institute of Medical Physics and Biophysics, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Alexander M Walter
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), FMP im CharitéCrossOver, Berlin, Germany.,Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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23
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Insect Behavioral Change and the Potential Contributions of Neuroinflammation-A Call for Future Research. Genes (Basel) 2021; 12:genes12040465. [PMID: 33805190 PMCID: PMC8064348 DOI: 10.3390/genes12040465] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/19/2021] [Accepted: 03/21/2021] [Indexed: 12/21/2022] Open
Abstract
Many organisms are able to elicit behavioral change in other organisms. Examples include different microbes (e.g., viruses and fungi), parasites (e.g., hairworms and trematodes), and parasitoid wasps. In most cases, the mechanisms underlying host behavioral change remain relatively unclear. There is a growing body of literature linking alterations in immune signaling with neuron health, communication, and function; however, there is a paucity of data detailing the effects of altered neuroimmune signaling on insect neuron function and how glial cells may contribute toward neuron dysregulation. It is important to consider the potential impacts of altered neuroimmune communication on host behavior and reflect on its potential role as an important tool in the "neuro-engineer" toolkit. In this review, we examine what is known about the relationships between the insect immune and nervous systems. We highlight organisms that are able to influence insect behavior and discuss possible mechanisms of behavioral manipulation, including potentially dysregulated neuroimmune communication. We close by identifying opportunities for integrating research in insect innate immunity, glial cell physiology, and neurobiology in the investigation of behavioral manipulation.
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24
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Vita DJ, Meier CJ, Broadie K. Neuronal fragile X mental retardation protein activates glial insulin receptor mediated PDF-Tri neuron developmental clearance. Nat Commun 2021; 12:1160. [PMID: 33608547 PMCID: PMC7896095 DOI: 10.1038/s41467-021-21429-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 01/08/2021] [Indexed: 01/31/2023] Open
Abstract
Glia engulf and phagocytose neurons during neural circuit developmental remodeling. Disrupting this pruning process contributes to Fragile X syndrome (FXS), a leading cause of intellectual disability and autism spectrum disorder in mammals. Utilizing a Drosophila FXS model central brain circuit, we identify two glial classes responsible for Draper-dependent elimination of developmentally transient PDF-Tri neurons. We find that neuronal Fragile X Mental Retardation Protein (FMRP) drives insulin receptor activation in glia, promotes glial Draper engulfment receptor expression, and negatively regulates membrane-molding ESCRT-III Shrub function during PDF-Tri neuron clearance during neurodevelopment in Drosophila. In this context, we demonstrate genetic interactions between FMRP and insulin receptor signaling, FMRP and Draper, and FMRP and Shrub in PDF-Tri neuron elimination. We show that FMRP is required within neurons, not glia, for glial engulfment, indicating FMRP-dependent neuron-to-glia signaling mediates neuronal clearance. We conclude neuronal FMRP drives glial insulin receptor activation to facilitate Draper- and Shrub-dependent neuronal clearance during neurodevelopment in Drosophila.
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Affiliation(s)
- Dominic J Vita
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Cole J Meier
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
- Kennedy Center for Research on Human Development, Nashville, TN, USA.
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA.
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25
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Lago-Baldaia I, Fernandes VM, Ackerman SD. More Than Mortar: Glia as Architects of Nervous System Development and Disease. Front Cell Dev Biol 2020; 8:611269. [PMID: 33381506 PMCID: PMC7767919 DOI: 10.3389/fcell.2020.611269] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 11/17/2020] [Indexed: 12/12/2022] Open
Abstract
Glial cells are an essential component of the nervous system of vertebrates and invertebrates. In the human brain, glia are as numerous as neurons, yet the importance of glia to nearly every aspect of nervous system development has only been expounded over the last several decades. Glia are now known to regulate neural specification, synaptogenesis, synapse function, and even broad circuit function. Given their ubiquity, it is not surprising that the contribution of glia to neuronal disease pathogenesis is a growing area of research. In this review, we will summarize the accumulated evidence of glial participation in several distinct phases of nervous system development and organization-neural specification, circuit wiring, and circuit function. Finally, we will highlight how these early developmental roles of glia contribute to nervous system dysfunction in neurodevelopmental and neurodegenerative disorders.
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Affiliation(s)
- Inês Lago-Baldaia
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Vilaiwan M. Fernandes
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Sarah D. Ackerman
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR, United States
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26
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Ozdowski EF, Wentzell JS, Engert SM, Abbott H, Sherwood NT. Suppression of spastin Mutant Phenotypes by Pak3 Loss Implicates a Role for Reactive Glia in AD-HSP. Front Neurosci 2020; 14:912. [PMID: 33013303 PMCID: PMC7499821 DOI: 10.3389/fnins.2020.00912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 08/06/2020] [Indexed: 11/13/2022] Open
Abstract
Neurodegenerative mechanisms due to mutations in spastin currently center on neuronal defects, primarily in microtubule and endomembrane regulation. Spastin loss in Drosophila larvae compromises neuronal microtubule distribution, alters synaptic bouton morphology, and weakens synaptic transmission at glutamatergic neuromuscular junction (NMJ) synapses. Pak3, a p21-activated kinase that promotes actin polymerization and filopodial projections, is required for these spastin mutant defects; animals lacking both genes have normal NMJs. Here we show that Pak3 is expressed in central and peripheral glial populations, and reduction of Pak3 specifically in subperineurial glial cells is sufficient to suppress the phenotypes associated with spastin loss. Subperineurial glia in the periphery ensheathe motor neuron axons and have been shown to extend actin-based projections that regulate synaptic terminals during normal NMJ development. We find that these subperineurial glial projections are Pak3-dependent and nearly twice as frequent in spastin mutants, while in Pak3, spastin double mutants, neither glial projections nor synaptic defects are observed. Spastin deficiency thus increases Pak3-dependent subperineurial glia activity, which is in turn required for neuronal defects. Our results demonstrate a central role for Pak3-mediated, altered glial behavior in the neuronal defects due to spastin loss, and suggest that a similar reactive glia-mediated mechanism may underlie human AD-HSP pathogenesis.
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Affiliation(s)
| | | | | | | | - Nina T. Sherwood
- Department of Biology, Duke University, Durham, NC, United States
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27
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Chou VT, Johnson SA, Van Vactor D. Synapse development and maturation at the drosophila neuromuscular junction. Neural Dev 2020; 15:11. [PMID: 32741370 PMCID: PMC7397595 DOI: 10.1186/s13064-020-00147-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 07/14/2020] [Indexed: 12/12/2022] Open
Abstract
Synapses are the sites of neuron-to-neuron communication and form the basis of the neural circuits that underlie all animal cognition and behavior. Chemical synapses are specialized asymmetric junctions between a presynaptic neuron and a postsynaptic target that form through a series of diverse cellular and subcellular events under the control of complex signaling networks. Once established, the synapse facilitates neurotransmission by mediating the organization and fusion of synaptic vesicles and must also retain the ability to undergo plastic changes. In recent years, synaptic genes have been implicated in a wide array of neurodevelopmental disorders; the individual and societal burdens imposed by these disorders, as well as the lack of effective therapies, motivates continued work on fundamental synapse biology. The properties and functions of the nervous system are remarkably conserved across animal phyla, and many insights into the synapses of the vertebrate central nervous system have been derived from studies of invertebrate models. A prominent model synapse is the Drosophila melanogaster larval neuromuscular junction, which bears striking similarities to the glutamatergic synapses of the vertebrate brain and spine; further advantages include the simplicity and experimental versatility of the fly, as well as its century-long history as a model organism. Here, we survey findings on the major events in synaptogenesis, including target specification, morphogenesis, and the assembly and maturation of synaptic specializations, with a emphasis on work conducted at the Drosophila neuromuscular junction.
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Affiliation(s)
- Vivian T Chou
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA
| | - Seth A Johnson
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.
| | - David Van Vactor
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.
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28
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Guangming G, Junhua G, Chenchen Z, Yang M, Wei X. Neurexin and Neuroligins Maintain the Balance of Ghost and Satellite Boutons at the Drosophila Neuromuscular Junction. Front Neuroanat 2020; 14:19. [PMID: 32581727 PMCID: PMC7296126 DOI: 10.3389/fnana.2020.00019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/26/2020] [Indexed: 11/22/2022] Open
Abstract
Neurexins and neuroligins are common synaptic adhesion molecules that are associated with autism and interact with each other in the synaptic cleft. The Drosophila neuromuscular junction (NMJ) bouton is a well-known model system in neuroscience, and ghost and satellite boutons, respectively, indicate the poor development and overgrowth of the NMJ boutons. However, the Drosophila neurexin (DNrx) and Drosophila neuroligins (DNlgs) are mainly observed in type Ib boutons, indicating the ultrastructural and developmental phenotypes of the Drosophila NMJ. Here, we identified the ultrastructural and developmental features of ghost and satellite boutons by utilizing dneurexin (dnrx) and dneuroligins (dnlgs) fly mutants and other associated fly strains. Ghost boutons contain synaptic vesicles with multiple diameters but very rarely contain T-bar structures and swollen or thin subsynaptic reticulum (SSR) membranes. The muscle cell membrane is invaginated at different sites, stretches to the ghost bouton from different directions, forms several layers that enwrap the ghost bouton, and then branches into the complex SSR. Satellite boutons share a common SSR membrane and present either a typical profile in which a main bouton is encircled by small boutons or two atypical profiles in which the small boutons are grouped together or distributed in beads without a main bouton. Electron and confocal microscopy data showed that dnrx, dnlg1, dnlg2, dnlg3, and dnlg4 mutations led to ghost boutons; the overexpression of dnrx, dnlg1, dnlg2, dnlg3, and dnlg4 led to satellite boutons; and the dnlg2;dnlg3 double mutation also led to satellite boutons. These results suggested that DNrx and DNlgs jointly maintain the development and function of NMJ boutons by regulating the balance of ghost and satellite boutons in Drosophila.
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Affiliation(s)
- Gan Guangming
- School of Medicine, Southeast University, Nanjing, China.,The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Geng Junhua
- The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Zhang Chenchen
- School of Medicine, Southeast University, Nanjing, China.,The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Mou Yang
- School of Medicine, Southeast University, Nanjing, China
| | - Xie Wei
- The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China.,Institute of Life Sciences, The Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, China
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29
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Cherra SJ, Goncharov A, Boassa D, Ellisman M, Jin Y. C. elegans MAGU-2/Mpp5 homolog regulates epidermal phagocytosis and synapse density. J Neurogenet 2020; 34:298-306. [PMID: 32366143 DOI: 10.1080/01677063.2020.1726915] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Synapses are dynamic connections that underlie essential functions of the nervous system. The addition, removal, and maintenance of synapses govern the flow of information in neural circuits throughout the lifetime of an animal. While extensive studies have elucidated many intrinsic mechanisms that neurons employ to modulate their connections, increasing evidence supports the roles of non-neuronal cells, such as glia, in synapse maintenance and circuit function. We previously showed that C. elegans epidermis regulates synapses through ZIG-10, a cell-adhesion protein of the immunoglobulin domain superfamily. Here we identified a member of the Pals1/MPP5 family, MAGU-2, that functions in the epidermis to modulate phagocytosis and the number of synapses by regulating ZIG-10 localization. Furthermore, we used light and electron microscopy to show that this epidermal mechanism removes neuronal membranes from the neuromuscular junction, dependent on the conserved phagocytic receptor CED-1. Together, our study shows that C. elegans epidermis constrains synaptic connectivity, in a manner similar to astrocytes and microglia in mammals, allowing optimized output of neural circuits.
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Affiliation(s)
- Salvatore J Cherra
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA.,Department of Neuroscience, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Alexandr Goncharov
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Daniela Boassa
- National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, CA, USA
| | - Mark Ellisman
- National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, CA, USA.,Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA.,Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, USA.,Department of Cellular and Molecular Medicine, School of Medicine, University of California San Diego, La Jolla, CA, USA
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30
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Vainchtein ID, Molofsky AV. Astrocytes and Microglia: In Sickness and in Health. Trends Neurosci 2020; 43:144-154. [PMID: 32044129 DOI: 10.1016/j.tins.2020.01.003] [Citation(s) in RCA: 244] [Impact Index Per Article: 61.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/28/2019] [Accepted: 01/11/2020] [Indexed: 01/05/2023]
Abstract
Healthy central nervous system (CNS) development and function require an intricate and balanced bidirectional communication between neurons and glia cells. In this review, we discuss the complementary roles of astrocytes and microglia in building the brain, including in the formation and refinement of synapses. We discuss recent evidence demonstrating how these interactions are coordinated in the transition from healthy physiology towards disease and discuss known and potential molecular mechanisms that mediate this cellular crosstalk.
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Affiliation(s)
- Ilia D Vainchtein
- Department of Psychiatry/Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Anna V Molofsky
- Department of Psychiatry/Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA.
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31
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Chou VT, Johnson S, Long J, Vounatsos M, Van Vactor D. dTACC restricts bouton addition and regulates microtubule organization at the Drosophila neuromuscular junction. Cytoskeleton (Hoboken) 2020; 77:4-15. [PMID: 31702858 PMCID: PMC7027520 DOI: 10.1002/cm.21578] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 10/11/2019] [Accepted: 11/05/2019] [Indexed: 12/20/2022]
Abstract
Regulation of the synaptic cytoskeleton is essential to proper neuronal development and wiring. Perturbations in neuronal microtubules (MTs) are associated with numerous pathologies, yet it remains unclear how changes in MTs may be coupled to synapse morphogenesis. Studies have identified many MT regulators that promote synapse growth. However, less is known about the factors that restrict growth, despite the potential links of synaptic overgrowth to severe neurological conditions. Here, we report that dTACC, which is implicated in MT assembly and stability, prevents synapse overgrowth at the Drosophila neuromuscular junction by restricting addition of new boutons throughout larval development. dTACC localizes to the axonal MT lattice and is required to maintain tubulin levels and the integrity of higher-order MT structures in motor axon terminals. While previous reports have demonstrated the roles of MT-stabilizing proteins in promoting synapse growth, our findings suggest that in certain contexts, MT stabilization may correlate with restricted growth.
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Affiliation(s)
- Vivian T. Chou
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
| | - Seth Johnson
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
| | - Jennifer Long
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
| | - Maxime Vounatsos
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
| | - David Van Vactor
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
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32
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Darabid H, St-Pierre-See A, Robitaille R. Purinergic-Dependent Glial Regulation of Synaptic Plasticity of Competing Terminals and Synapse Elimination at the Neuromuscular Junction. Cell Rep 2019; 25:2070-2082.e6. [PMID: 30463006 DOI: 10.1016/j.celrep.2018.10.075] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 07/23/2018] [Accepted: 10/19/2018] [Indexed: 01/20/2023] Open
Abstract
The precise wiring of synaptic connections requires the elimination of supernumerary inputs competing for innervation of the same target cell. This competition is activity-dependent, strengthening some inputs whereas others are eliminated. Although glial cells are required for the elimination and clearance of terminals, their involvement in activity-dependent synaptic competition remains ill-defined. Here, we used the developing neuromuscular junctions of mice to show that perisynaptic glial cells, through 2Y1 purinergic receptors (P2Y1Rs), decode synaptic efficacy of competing terminals in a Ca2+-dependent manner. This glial activity induces long-lasting synaptic potentiation of strong but not weak terminals via presynaptic adenosine 2A receptors. Blockade of glial activity by intracellular Ca2+ chelation or blockade of P2Y1Rs prevents this plasticity. In addition, blockade of P2Y1Rs delays synapse elimination in vivo. Hence, P2Y1Rs drive glial cell regulation of strong synaptic inputs and influence synapse competition and elimination.
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Affiliation(s)
- Houssam Darabid
- Département de Neurosciences, Université de Montréal, PO Box 6128, Station Centre-ville, Montréal, QC H3C 3J7, Canada; Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Alexandre St-Pierre-See
- Département de Neurosciences, Université de Montréal, PO Box 6128, Station Centre-ville, Montréal, QC H3C 3J7, Canada; Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Richard Robitaille
- Département de Neurosciences, Université de Montréal, PO Box 6128, Station Centre-ville, Montréal, QC H3C 3J7, Canada; Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-ville, Montréal, QC H3C 3J7, Canada.
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33
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Hakim-Mishnaevski K, Flint-Brodsly N, Shklyar B, Levy-Adam F, Kurant E. Glial Phagocytic Receptors Promote Neuronal Loss in Adult Drosophila Brain. Cell Rep 2019; 29:1438-1448.e3. [DOI: 10.1016/j.celrep.2019.09.086] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 07/30/2019] [Accepted: 09/27/2019] [Indexed: 12/22/2022] Open
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34
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Liddelow SA. Modern approaches to investigating non-neuronal aspects of Alzheimer's disease. FASEB J 2019; 33:1528-1535. [PMID: 30703873 DOI: 10.1096/fj.201802592] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The slow, continuous, devastating march of Alzheimer's disease continues to move across the globe. As a society, we are at a loss for options to treat or reverse the death of neurons-the final, apparently inescapable, hallmark of the disease. A continued focus on these dying neurons has taught us much about the disease but with no knowledge-based effective treatment in sight. A surge of interest in non-neuronal cells, including glia, blood vasculature, and immune cells, has shed new light on how we may better diagnose and treat patients. This may be our best hope to treat the millions patients with cognitive decline and memory loss.-Liddelow, S. A. Modern approaches to investigating non-neuronal aspects of Alzheimer's disease.
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Affiliation(s)
- Shane A Liddelow
- Neuroscience Institute and Department of Neuroscience and Physiology, New York University Langone Medical Center, New York, New York, USA; and.,Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, Victoria, Australia
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35
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Two Pathways for the Activity-Dependent Growth and Differentiation of Synaptic Boutons in Drosophila. eNeuro 2019; 6:ENEURO.0060-19.2019. [PMID: 31387877 PMCID: PMC6709223 DOI: 10.1523/eneuro.0060-19.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 07/15/2019] [Accepted: 07/26/2019] [Indexed: 11/21/2022] Open
Abstract
Synapse formation can be promoted by intense activity. At the Drosophila larval neuromuscular junction (NMJ), new synaptic boutons can grow acutely in response to patterned stimulation. We combined confocal imaging with electron microscopy and tomography to investigate the initial stages of growth and differentiation of new presynaptic boutons at the Drosophila NMJ. We found that the new boutons can form rapidly in intact larva in response to intense crawling activity, and we observed two different patterns of bouton formation and maturation. The first pathway involves the growth of filopodia followed by a formation of boutons that are initially devoid of synaptic vesicles (SVs) but filled with filamentous matrix. The second pathway involves rapid budding of synaptic boutons packed with SVs, and these more mature boutons are sometimes capable of exocytosis/endocytosis. We demonstrated that intense activity predominantly promotes the second pathway, i.e., budding of more mature boutons filled with SVs. We also showed that this pathway depends on synapsin (Syn), a neuronal protein which reversibly associates with SVs and mediates their clustering via a protein kinase A (PKA)-dependent mechanism. Finally, we took advantage of the temperature-sensitive mutant sei to demonstrate that seizure activity can promote very rapid budding of new boutons filled with SVs, and this process occurs at scale of minutes. Altogether, these results demonstrate that intense activity acutely and selectively promotes rapid budding of new relatively mature presynaptic boutons filled with SVs, and that this process is regulated via a PKA/Syn-dependent pathway.
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36
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Abstract
Maturation of neuronal circuits requires selective elimination of synaptic connections. Although neuron-intrinsic mechanisms are important in this process, it is increasingly recognized that glial cells also play a critical role. Without proper functioning of these cells, the number, morphology, and function of synaptic contacts are profoundly altered, resulting in abnormal connectivity and behavioral abnormalities. In addition to their role in synaptic refinement, glial cells have also been implicated in pathological synapse loss and dysfunction following injury or nervous system degeneration in adults. Although mechanisms regulating glia-mediated synaptic elimination are still being uncovered, it is clear this complex process involves many cues that promote and inhibit the removal of specific synaptic connections. Gaining a greater understanding of these signals and the contribution of different cell types will not only provide insight into this critical biological event but also be instrumental in advancing knowledge of brain development and neural disease.
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Affiliation(s)
- Daniel K. Wilton
- Department of Neurology and F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Lasse Dissing-Olesen
- Department of Neurology and F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Beth Stevens
- Department of Neurology and F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
- Stanley Center, Broad Institute, Cambridge, Massachusetts 02142, USA
- Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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37
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Perry JSA, Ravichandran KS. Embryonic Trogocytosis: Neighborly Nibbling during Development. Curr Biol 2019; 27:R68-R70. [PMID: 28118592 DOI: 10.1016/j.cub.2016.11.043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
New work in Caenorhabditis elegans shows that during embryogenesis endodermal cells interact with and regulate primordial germ cells by actively excising and digesting germ cell lobes. Endodermal cells utilize proteins linked to endocytosis to perform this unique 'cannibalistic' process.
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Affiliation(s)
- Justin S A Perry
- Department of Microbiology, Immunology, and Cancer Biology and the Center for Cell Clearance, University of Virginia, Charlottesville, VA, USA
| | - Kodi S Ravichandran
- Department of Microbiology, Immunology, and Cancer Biology and the Center for Cell Clearance, University of Virginia, Charlottesville, VA, USA.
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38
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Nakano R, Iwamura M, Obikawa A, Togane Y, Hara Y, Fukuhara T, Tomaru M, Takano-Shimizu T, Tsujimura H. Cortex glia clear dead young neurons via Drpr/dCed-6/Shark and Crk/Mbc/dCed-12 signaling pathways in the developing Drosophila optic lobe. Dev Biol 2019; 453:68-85. [PMID: 31063730 DOI: 10.1016/j.ydbio.2019.05.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 04/25/2019] [Accepted: 05/02/2019] [Indexed: 02/06/2023]
Abstract
The molecular and cellular mechanism for clearance of dead neurons was explored in the developing Drosophila optic lobe. During development of the optic lobe, many neural cells die through apoptosis, and corpses are immediately removed in the early pupal stage. Most of the cells that die in the optic lobe are young neurons that have not extended neurites. In this study, we showed that clearance was carried out by cortex glia via a phagocytosis receptor, Draper (Drpr). drpr expression in cortex glia from the second instar larval to early pupal stages was required and sufficient for clearance. Drpr that was expressed in other subtypes of glia did not mediate clearance. Shark and Ced-6 mediated clearance of Drpr. The Crk/Mbc/dCed-12 pathway was partially involved in clearance, but the role was minor. Suppression of the function of Pretaporter, CaBP1 and phosphatidylserine delayed clearance, suggesting a possibility for these molecules to function as Drpr ligands in the developing optic lobe.
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Affiliation(s)
- Ryosuke Nakano
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan; Department of Drosophila Genomics and Genetic Resources, Center for Advanced Insect Research Promotion, Kyoto Institute of Technology, Saga Ippongi-cho, Ukyo-ku, Kyoto 616-8354, Japan
| | - Masashi Iwamura
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Akiko Obikawa
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan; Department of Drosophila Genomics and Genetic Resources, Center for Advanced Insect Research Promotion, Kyoto Institute of Technology, Saga Ippongi-cho, Ukyo-ku, Kyoto 616-8354, Japan
| | - Yu Togane
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Yusuke Hara
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Toshiyuki Fukuhara
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Masatoshi Tomaru
- Department of Drosophila Genomics and Genetic Resources, Center for Advanced Insect Research Promotion, Kyoto Institute of Technology, Saga Ippongi-cho, Ukyo-ku, Kyoto 616-8354, Japan
| | - Toshiyuki Takano-Shimizu
- Department of Drosophila Genomics and Genetic Resources, Center for Advanced Insect Research Promotion, Kyoto Institute of Technology, Saga Ippongi-cho, Ukyo-ku, Kyoto 616-8354, Japan
| | - Hidenobu Tsujimura
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
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39
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Sapar ML, Han C. Die in pieces: How Drosophila sheds light on neurite degeneration and clearance. J Genet Genomics 2019; 46:187-199. [PMID: 31080046 DOI: 10.1016/j.jgg.2019.03.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 03/24/2019] [Accepted: 03/26/2019] [Indexed: 01/08/2023]
Abstract
Dendrites and axons are delicate neuronal membrane extensions that undergo degeneration after physical injuries. In neurodegenerative diseases, they often degenerate prior to neuronal death. Understanding the mechanisms of neurite degeneration has been an intense focus of neurobiology research in the last two decades. As a result, many discoveries have been made in the molecular pathways that lead to neurite degeneration and the cell-cell interactions responsible for the subsequent clearance of neuronal debris. Drosophila melanogaster has served as a prime in vivo model system for identifying and characterizing the key molecular players in neurite degeneration, thanks to its genetic tractability and easy access to its nervous system. The knowledge learned in the fly provided targets and fuel for studies in other model systems that have further enhanced our understanding of neurodegeneration. In this review, we will introduce the experimental systems developed in Drosophila to investigate injury-induced neurite degeneration, and then discuss the biological pathways that drive degeneration. We will also cover what is known about the mechanisms of how phagocytes recognize and clear degenerating neurites, and how recent findings in this area enhance our understanding of neurodegenerative disease pathology.
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Affiliation(s)
- Maria L Sapar
- Weill Institute for Cell and Molecular Biology, Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Chun Han
- Weill Institute for Cell and Molecular Biology, Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA.
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40
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Draper I, Saha M, Stonebreaker H, Salomon RN, Matin B, Kang PB. The impact of Megf10/Drpr gain-of-function on muscle development in Drosophila. FEBS Lett 2019; 593:680-696. [PMID: 30802937 DOI: 10.1002/1873-3468.13348] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 02/12/2019] [Accepted: 02/13/2019] [Indexed: 11/07/2022]
Abstract
Recessive mutations in multiple epidermal growth factor-like domains 10 (MEGF10) underlie a rare congenital muscle disease known as MEGF10 myopathy. MEGF10 and its Drosophila homolog Draper (Drpr) are transmembrane receptors expressed in muscle and glia. Drpr deficiency is known to result in muscle abnormalities in flies. In the current study, flies that ubiquitously overexpress Drpr, or mouse Megf10, display developmental arrest. The phenotype is reproduced with overexpression in muscle, but not in other tissues, and with overexpression during intermediate stages of myogenesis, but not in myoblasts. We find that tubular muscle subtypes are particularly sensitive to Megf10/Drpr overexpression. Complementary genetic analyses show that Megf10/Drpr and Notch may interact to regulate myogenesis. Our findings provide a basis for investigating MEGF10 in muscle development using Drosophila.
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Affiliation(s)
- Isabelle Draper
- Department of Medicine, Molecular Cardiology Research Institute, Tufts Medical Center, Boston, MA, USA
| | - Madhurima Saha
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, USA
| | | | - Robert N Salomon
- Department of Pathology and Laboratory Medicine, Tufts Medical Center, Boston, MA, USA
| | - Bahar Matin
- Department of Medicine, Molecular Cardiology Research Institute, Tufts Medical Center, Boston, MA, USA
| | - Peter B Kang
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, USA.,Department of Neurology, Boston Children's Hospital, MA, USA.,Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, FL, USA.,Department of Neurology, University of Florida College of Medicine, Gainesville, FL, USA.,Genetics Institute and Myology Institute, University of Florida, Gainesville, FL, USA
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41
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Guttenplan KA, Liddelow SA. Astrocytes and microglia: Models and tools. J Exp Med 2018; 216:71-83. [PMID: 30541903 PMCID: PMC6314517 DOI: 10.1084/jem.20180200] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 08/16/2018] [Accepted: 11/26/2018] [Indexed: 01/05/2023] Open
Abstract
An amazing array of tools both old and new are available to investigate the function of astrocytes and microglia. Guttenplan and Liddelow discuss tools available to study the physiology and pathophysiology of these cells both in vivo and in culture systems. Glial cells serve as fundamental regulators of the central nervous system in development, homeostasis, and disease. Discoveries into the function of these cells have fueled excitement in glial research, with enthusiastic researchers addressing fundamental questions about glial biology and producing new scientific tools for the community. Here, we outline the pros and cons of in vivo and in vitro techniques to study astrocytes and microglia with the goal of helping researchers quickly identify the best approach for a given research question in the context of glial biology. It is truly a great time to be a glial biologist.
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Affiliation(s)
| | - Shane A Liddelow
- Neuroscience Institute, NYU Langone Medical Center, New York, NY.,Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY.,Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, Australia
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42
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Yildirim K, Petri J, Kottmeier R, Klämbt C. Drosophila glia: Few cell types and many conserved functions. Glia 2018; 67:5-26. [DOI: 10.1002/glia.23459] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 04/25/2018] [Accepted: 05/04/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Kerem Yildirim
- Institute for Neuro and Behavioral Biology; University of Münster; Badestraße 9, 48149 Münster Germany
| | - Johanna Petri
- Institute for Neuro and Behavioral Biology; University of Münster; Badestraße 9, 48149 Münster Germany
| | - Rita Kottmeier
- Institute for Neuro and Behavioral Biology; University of Münster; Badestraße 9, 48149 Münster Germany
| | - Christian Klämbt
- Institute for Neuro and Behavioral Biology; University of Münster; Badestraße 9, 48149 Münster Germany
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43
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Stawarski M, Justs KA, Hernandez RX, Macleod GT. The application of 'kisser' probes for resolving the distribution and microenvironment of membrane proteins in situ. J Neurogenet 2018; 32:236-245. [PMID: 30175639 DOI: 10.1080/01677063.2018.1503260] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Membrane proteins play a lead role in the formation and function of synapses, but, despite revolutions in immunology and molecular genetics, limitations persist in our ability to investigate membrane proteins in the context of an intact synapse. Here, we introduce a simple but novel approach to resolving the distribution of endogenous membrane proteins in either live or fixed tissues. The technique involves transgenic expression of a protein with an extracellular tag, a generic transmembrane domain, and an intracellular terminus that mimics the intracellular anchoring motifs of the endogenous protein of interest. We provide three examples where these kisser probes can be used to answer questions regarding the synaptic distribution of endogenous proteins and their microenvironment that would be difficult to resolve by other contemporary means: (i) the live distribution of untagged proteins at the neuromuscular junction (Cacophony and Shaker), (ii) the relative distribution of an untagged protein (PMCA) in pre- versus post-synaptic membranes separated by only 20 nm across the cleft of a fixed synapse, and (iii) the live targeting of functional probes (chemical and protein fluorescent pH reporters) to membrane protein-defined subcellular domains.
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Affiliation(s)
- Michal Stawarski
- a Department of Biomedicine , University of Basel , Basel , Switzerland
| | - Karlis Anthony Justs
- b Wilkes Honors College , Florida Atlantic University, John D MacArthur Campus , Jupiter , FL, USA
| | - Roberto Xander Hernandez
- b Wilkes Honors College , Florida Atlantic University, John D MacArthur Campus , Jupiter , FL, USA
| | - Gregory Talisker Macleod
- b Wilkes Honors College , Florida Atlantic University, John D MacArthur Campus , Jupiter , FL, USA
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44
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Hilu-Dadia R, Hakim-Mishnaevski K, Levy-Adam F, Kurant E. Draper-mediated JNK signaling is required for glial phagocytosis of apoptotic neurons during Drosophila metamorphosis. Glia 2018. [PMID: 29520845 DOI: 10.1002/glia.23322] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Development of the central nervous system involves elimination of superfluous neurons through apoptosis and subsequent phagocytosis. In Drosophila, this occurs mainly during three developmental stages: embryogenesis, metamorphosis and emerging adult. Two transmembrane glial phagocytic receptors, SIMU (homolog of the mammalian Stabilin-2) and Draper (homolog of the mammalian MEGF10 and Jedi), mediate glial phagocytosis of apoptotic neurons during embryogenesis. However, less is known about the removal of apoptotic neurons during later stages of development. Here we show that during metamorphosis, Draper plays a critical role in apoptotic cell clearance by glia, whereas SIMU, which is mostly expressed in pupal macrophages outside the brain, is not involved in glial phagocytosis. We found that Draper activates Drosophila c-Jun N-terminal kinase (dJNK) signaling predominantly in the ensheathing glia and astrocytes, where it is required for efficient removal of apoptotic neurons. Our data suggest that besides the dJNK pathway, Draper also triggers an additional signaling pathway capable of removing apoptotic neurons in the pupal brain. This study thus reveals that SIMU unexpectedly is not involved in glial phagocytosis of apoptotic neurons during metamorphosis and highlights the novel role of dJNK signaling in developmental apoptotic cell clearance downstream of Draper.
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Affiliation(s)
- Reut Hilu-Dadia
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa, 34988, Israel.,Department of Genetics and Developmental Biology, The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, 31096, Israel
| | - Ketty Hakim-Mishnaevski
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa, 34988, Israel
| | - Flonia Levy-Adam
- Department of Genetics and Developmental Biology, The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, 31096, Israel
| | - Estee Kurant
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa, 34988, Israel.,Department of Genetics and Developmental Biology, The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, 31096, Israel
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45
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Jordán-Álvarez S, Santana E, Casas-Tintó S, Acebes Á, Ferrús A. The equilibrium between antagonistic signaling pathways determines the number of synapses in Drosophila. PLoS One 2017; 12:e0184238. [PMID: 28892511 PMCID: PMC5593197 DOI: 10.1371/journal.pone.0184238] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 08/21/2017] [Indexed: 12/12/2022] Open
Abstract
The number of synapses is a major determinant of behavior and many neural diseases exhibit deviations in that number. However, how signaling pathways control this number is still poorly understood. Using the Drosophila larval neuromuscular junction, we show here a PI3K-dependent pathway for synaptogenesis which is functionally connected with other previously known elements including the Wit receptor, its ligand Gbb, and the MAPkinases cascade. Based on epistasis assays, we determined the functional hierarchy within the pathway. Wit seems to trigger signaling through PI3K, and Ras85D also contributes to the initiation of synaptogenesis. However, contrary to other signaling pathways, PI3K does not require Ras85D binding in the context of synaptogenesis. In addition to the MAPK cascade, Bsk/JNK undergoes regulation by Puc and Ras85D which results in a narrow range of activity of this kinase to determine normalcy of synapse number. The transcriptional readout of the synaptogenesis pathway involves the Fos/Jun complex and the repressor Cic. In addition, we identified an antagonistic pathway that uses the transcription factors Mad and Medea and the microRNA bantam to down-regulate key elements of the pro-synaptogenesis pathway. Like its counterpart, the anti-synaptogenesis signaling uses small GTPases and MAPKs including Ras64B, Ras-like-a, p38a and Licorne. Bantam downregulates the pro-synaptogenesis factors PI3K, Hiw, Ras85D and Bsk, but not AKT. AKT, however, can suppress Mad which, in conjunction with the reported suppression of Mad by Hiw, closes the mutual regulation between both pathways. Thus, the number of synapses seems to result from the balanced output from these two pathways.
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Affiliation(s)
| | | | | | - Ángel Acebes
- Institute Cajal C.S.I.C., Madrid, Spain
- * E-mail: (AF); (AA)
| | - Alberto Ferrús
- Institute Cajal C.S.I.C., Madrid, Spain
- * E-mail: (AF); (AA)
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46
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Petralia RS, Wang YX, Mattson MP, Yao PJ. Invaginating Presynaptic Terminals in Neuromuscular Junctions, Photoreceptor Terminals, and Other Synapses of Animals. Neuromolecular Med 2017; 19:193-240. [PMID: 28612182 PMCID: PMC6518423 DOI: 10.1007/s12017-017-8445-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 06/01/2017] [Indexed: 10/19/2022]
Abstract
Typically, presynaptic terminals form a synapse directly on the surface of postsynaptic processes such as dendrite shafts and spines. However, some presynaptic terminals invaginate-entirely or partially-into postsynaptic processes. We survey these invaginating presynaptic terminals in all animals and describe several examples from the central nervous system, including giant fiber systems in invertebrates, and cup-shaped spines, electroreceptor synapses, and some specialized auditory and vestibular nerve terminals in vertebrates. We then examine mechanoreceptors and photoreceptors, concentrating on the complex of pre- and postsynaptic processes found in basal invaginations of the cell. We discuss in detail the role of vertebrate invaginating horizontal cell processes in both chemical and electrical feedback mechanisms. We also discuss the common presence of indenting or invaginating terminals in neuromuscular junctions on muscles of most kinds of animals, and especially discuss those of Drosophila and vertebrates. Finally, we consider broad questions about the advantages of possessing invaginating presynaptic terminals and describe some effects of aging and disease, especially on neuromuscular junctions. We suggest that the invagination is a mechanism that can enhance both chemical and electrical interactions at the synapse.
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Affiliation(s)
- Ronald S Petralia
- Advanced Imaging Core, NIDCD/NIH, 35A Center Drive, Room 1E614, Bethesda, MD, 20892-3729, USA.
| | - Ya-Xian Wang
- Advanced Imaging Core, NIDCD/NIH, 35A Center Drive, Room 1E614, Bethesda, MD, 20892-3729, USA
| | - Mark P Mattson
- Laboratory of Neurosciences, NIA/NIH, Baltimore, MD, 21224, USA
| | - Pamela J Yao
- Laboratory of Neurosciences, NIA/NIH, Baltimore, MD, 21224, USA
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47
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GULP1/CED-6 ameliorates amyloid-β toxicity in a Drosophila model of Alzheimer's disease. Oncotarget 2017; 8:99274-99283. [PMID: 29245900 PMCID: PMC5725091 DOI: 10.18632/oncotarget.20062] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 07/30/2017] [Indexed: 01/24/2023] Open
Abstract
Amyloidogenic processing of APP by β- and γ-secretases leads to the generation of amyloid-β peptide (Aβ), and the accumulation of Aβ in senile plaques is a hallmark of Alzheimer’s disease (AD). Understanding the mechanisms of APP processing is therefore paramount. Increasing evidence suggests that APP intracellular domain (AICD) interacting proteins influence APP processing. In this study, we characterized the overexpression of AICD interactor GULP1 in a Drosophila AD model expressing human BACE and APP695. Transgenic GULP1 significantly lowered the levels of both Aβ1-40 and Aβ1-42 without decreasing the BACE and APP695 levels. Overexpression of GULP1 also reduced APP/BACE-mediated retinal degeneration, rescued motor dysfunction and extended longevity of the flies. Our results indicate that GULP1 regulate APP processing and reduce neurotoxicity in a Drosophila AD model.
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48
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Hosaka Y, Inoshita T, Shiba-Fukushima K, Cui C, Arano T, Imai Y, Hattori N. Reduced TDP-43 Expression Improves Neuronal Activities in a Drosophila Model of Perry Syndrome. EBioMedicine 2017. [PMID: 28625517 PMCID: PMC5514405 DOI: 10.1016/j.ebiom.2017.06.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Parkinsonian Perry syndrome, involving mutations in the dynein motor component dynactin or p150Glued, is characterized by TDP-43 pathology in affected brain regions, including the substantia nigra. However, the molecular relationship between p150Glued and TDP-43 is largely unknown. Here, we report that a reduction in TDP-43 protein levels alleviates the synaptic defects of neurons expressing the Perry mutant p150G50R in Drosophila. Dopaminergic expression of p150G50R, which decreases dopamine release, disrupts motor ability and reduces the lifespan of Drosophila. p150G50R expression also causes aggregation of dense core vesicles (DCVs), which contain monoamines and neuropeptides, and disrupts the axonal flow of DCVs, thus decreasing synaptic strength. The above phenotypes associated with Perry syndrome are improved by the removal of a copy of Drosophila TDP-43 TBPH, thus suggesting that the stagnation of axonal transport by dynactin mutations promotes TDP-43 aggregation and interferes with the dynamics of DCVs and synaptic activities. Fly model of Perry syndrome exhibits motor disturbance and impaired dopamine release. Perry mutation in dynactin produces aggregation of dense core vesicles (DCVs) in axons and disrupts axonal flux of DCVs. Removal of a copy of the TDP-43 gene improves retrograde flux of DCVs.
Parkinsonian Perry syndrome (PS), caused by mutations in a component of the retrograde transport complex, Dynactin, is pathologically characterized by the accumulation of an RNA-binding protein, TDP-43, in affected neurons. The neuronal accumulation of TDP-43 is observed in various neurodegenerative diseases including amyotrophic lateral sclerosis and Alzheimer's disease. We report that decreased TDP-43 expression improves defects in the axonal transport of dense core vesicles and in the dopamine release in a Drosophila PS model. This study provides insight into the possibility that a transient decrease in TDP-43 in neurons may be a promising therapeutic approach for treating neurodegenerative disorders associated with TDP-43 pathology, including PS.
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Affiliation(s)
- Yuka Hosaka
- Department of Neurology, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Tsuyoshi Inoshita
- Department of Treatment and Research in Multiple Sclerosis and Neuro-intractable Disease, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Kahori Shiba-Fukushima
- Department of Treatment and Research in Multiple Sclerosis and Neuro-intractable Disease, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Changxu Cui
- Department of Research for Parkinson's Disease, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Taku Arano
- Center for Genomic and Regenerative Medicine, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Yuzuru Imai
- Department of Neurology, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan; Department of Treatment and Research in Multiple Sclerosis and Neuro-intractable Disease, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan.
| | - Nobutaka Hattori
- Department of Neurology, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan; Department of Treatment and Research in Multiple Sclerosis and Neuro-intractable Disease, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan; Department of Research for Parkinson's Disease, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan.
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49
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Wang CH, Huang YC, Chen PY, Cheng YJ, Kao HH, Pi H, Chien CT. USP5/Leon deubiquitinase confines postsynaptic growth by maintaining ubiquitin homeostasis through Ubiquilin. eLife 2017; 6. [PMID: 28489002 PMCID: PMC5438252 DOI: 10.7554/elife.26886] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 05/09/2017] [Indexed: 12/14/2022] Open
Abstract
Synapse formation and growth are tightly controlled processes. How synaptic growth is terminated after reaching proper size remains unclear. Here, we show that Leon, the Drosophila USP5 deubiquitinase, controls postsynaptic growth. In leon mutants, postsynaptic specializations of neuromuscular junctions are dramatically expanded, including the subsynaptic reticulum, the postsynaptic density, and the glutamate receptor cluster. Expansion of these postsynaptic features is caused by a disruption of ubiquitin homeostasis with accumulation of free ubiquitin chains and ubiquitinated substrates in the leon mutant. Accumulation of Ubiquilin (Ubqn), the ubiquitin receptor whose human homolog ubiquilin 2 is associated with familial amyotrophic lateral sclerosis, also contributes to defects in postsynaptic growth and ubiquitin homeostasis. Importantly, accumulations of postsynaptic proteins cause different aspects of postsynaptic overgrowth in leon mutants. Thus, the deubiquitinase Leon maintains ubiquitin homeostasis and proper Ubqn levels, preventing postsynaptic proteins from accumulation to confine postsynaptic growth. DOI:http://dx.doi.org/10.7554/eLife.26886.001
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Affiliation(s)
- Chien-Hsiang Wang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Institute of Neuroscience, National Yang Ming University, Taipei, Taiwan
| | - Yi-Chun Huang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Department of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan
| | - Pei-Yi Chen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Institute of Neuroscience, National Yang Ming University, Taipei, Taiwan
| | - Ying-Ju Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Hsiu-Hua Kao
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Haiwei Pi
- Department of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Institute of Neuroscience, National Yang Ming University, Taipei, Taiwan
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50
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Van Vactor D, Sigrist SJ. Presynaptic morphogenesis, active zone organization and structural plasticity in Drosophila. Curr Opin Neurobiol 2017; 43:119-129. [PMID: 28388491 DOI: 10.1016/j.conb.2017.03.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 03/06/2017] [Accepted: 03/08/2017] [Indexed: 12/31/2022]
Abstract
Effective adaptation of neural circuit function to a changing environment requires many forms of plasticity. Among these, structural plasticity is one of the most durable, and is also an intrinsic part of the developmental logic for the formation and refinement of synaptic connectivity. Structural plasticity of presynaptic sites can involve the addition, remodeling, or removal of pre- and post-synaptic elements. However, this requires coordination of morphogenesis and assembly of the subcellular machinery for neurotransmitter release within the presynaptic neuron, as well as coordination of these events with the postsynaptic cell. While much progress has been made in revealing the cell biological mechanisms of postsynaptic structural plasticity, our understanding of presynaptic mechanisms is less complete.
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Affiliation(s)
- David Van Vactor
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA; Okinawa Institute of Science and Technology, Graduate University, Tancha 1919-1, Onna-son, Okinawa, Japan.
| | - Stephan J Sigrist
- Institut für Biologie/Genetik and NeuroCure, Freie Universität Berlin, Takustrasse 6, D-14195 Berlin, Germany.
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