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Brown EB, Lloyd E, Riley R, Panahidizjikan Z, Martin-Peña A, McFarlane S, Dahanukar A, Keene AC. Aging is associated with a modality-specific decline in taste. iScience 2024; 27:110919. [PMID: 39381735 PMCID: PMC11460507 DOI: 10.1016/j.isci.2024.110919] [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: 02/16/2024] [Revised: 06/27/2024] [Accepted: 09/06/2024] [Indexed: 10/10/2024] Open
Abstract
Deficits in chemosensory processing are associated with healthy aging, as well as numerous neurodegenerative disorders, including Alzheimer's disease (AD). The fruit fly, Drosophila melanogaster, is a powerful model for studying chemosensation, aging, and aging-related pathologies, yet the effects of aging and neurodegeneration on taste function remain largely unexplored. Aging impaired response to sugars, but not medium-chain fatty acids that are sensed by a shared population of neurons. Selective expression of the human amyloid beta (Aβ) peptide phenocopied the effects of aging. Functional imaging of gustatory axon terminals revealed reduced response to sugar, but not fatty acids. Axonal innervation of the fly taste center was largely intact in aged flies; however, axonal innervation was reduced upon expression of Aβ. A comparison of transcript expression within the sugar-sensing taste neurons revealed age-related changes in 66 genes. Together, these findings suggest that different mechanisms underly taste deficits in aged and AD model flies.
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Affiliation(s)
- Elizabeth B. Brown
- Department of Biological Sciences, Florida State University, Tallahassee, FL 32306, USA
- Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
| | - Evan Lloyd
- Department of Biological Sciences, Florida State University, Tallahassee, FL 32306, USA
- Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
| | - Rose Riley
- Department of Biological Sciences, Florida State University, Tallahassee, FL 32306, USA
| | - Zohre Panahidizjikan
- Department of Biological Sciences, Florida State University, Tallahassee, FL 32306, USA
| | - Alfonso Martin-Peña
- Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Samuel McFarlane
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Anupama Dahanukar
- Interdepartmental Neuroscience Program, University of California, Riverside, Riverside, CA 92521, USA
- Department of Molecular, Cell & Systems Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Alex C. Keene
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
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2
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Pribbenow C, Owald D. Skewing information flow through pre- and postsynaptic plasticity in the mushroom bodies of Drosophila. Learn Mem 2024; 31:a053919. [PMID: 38876487 PMCID: PMC11199954 DOI: 10.1101/lm.053919.124] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 04/26/2024] [Indexed: 06/16/2024]
Abstract
Animal brains need to store information to construct a representation of their environment. Knowledge of what happened in the past allows both vertebrates and invertebrates to predict future outcomes by recalling previous experience. Although invertebrate and vertebrate brains share common principles at the molecular, cellular, and circuit-architectural levels, there are also obvious differences as exemplified by the use of acetylcholine versus glutamate as the considered main excitatory neurotransmitters in the respective central nervous systems. Nonetheless, across central nervous systems, synaptic plasticity is thought to be a main substrate for memory storage. Therefore, how brain circuits and synaptic contacts change following learning is of fundamental interest for understanding brain computations tied to behavior in any animal. Recent progress has been made in understanding such plastic changes following olfactory associative learning in the mushroom bodies (MBs) of Drosophila A current framework of memory-guided behavioral selection is based on the MB skew model, in which antagonistic synaptic pathways are selectively changed in strength. Here, we review insights into plasticity at dedicated Drosophila MB output pathways and update what is known about the plasticity of both pre- and postsynaptic compartments of Drosophila MB neurons.
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Affiliation(s)
- Carlotta Pribbenow
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany
| | - David Owald
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany
- Einstein Center for Neurosciences Berlin, 10117 Berlin, Germany
- NeuroCure, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany
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3
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Weiss JT, Blundell MZ, Singh P, Donlea JM. Sleep deprivation drives brain-wide changes in cholinergic presynapse abundance in Drosophila melanogaster. Proc Natl Acad Sci U S A 2024; 121:e2312664121. [PMID: 38498719 PMCID: PMC10990117 DOI: 10.1073/pnas.2312664121] [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: 07/24/2023] [Accepted: 02/19/2024] [Indexed: 03/20/2024] Open
Abstract
Sleep is an evolutionarily conserved state that supports brain functions, including synaptic plasticity, in species across the animal kingdom. Here, we examine the neuroanatomical and cell-type distribution of presynaptic scaling in the fly brain after sleep loss. We previously found that sleep loss drives accumulation of the active zone scaffolding protein Bruchpilot (BRP) within cholinergic Kenyon cells of the Drosophila melanogaster mushroom body (MB), but not in other classes of MB neurons. To test whether similar cell type-specific trends in plasticity occur broadly across the brain, we used a flp-based genetic reporter to label presynaptic BRP in cholinergic, dopaminergic, GABAergic, or glutamatergic neurons. We then collected whole-brain confocal image stacks of BRP intensity to systematically quantify BRP, a marker of presynapse abundance, across 37 neuropil regions of the central fly brain. Our results indicate that sleep loss, either by overnight (12-h) mechanical stimulation or chronic sleep disruption in insomniac mutants, broadly elevates cholinergic synapse abundance across the brain, while synapse abundance in neurons that produce other neurotransmitters undergoes weaker, if any, changes. Extending sleep deprivation to 24 h drives brain-wide upscaling in glutamatergic, but not other, synapses. Finally, overnight male-male social pairings induce increased BRP in excitatory synapses despite male-female pairings eliciting more waking activity, suggesting experience-specific plasticity. Within neurotransmitter class and waking context, BRP changes are similar across the 37 neuropil domains, indicating that similar synaptic scaling rules may apply across the brain during acute sleep loss and that sleep need may broadly alter excitatory-inhibitory balance in the central brain.
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Affiliation(s)
- Jacqueline T. Weiss
- Department of Neurobiology, David Geffen School of Medicine at University of California, Los Angeles, CA90095
- Neuroscience Interdepartmental Program, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Mei Z. Blundell
- Department of Neurobiology, David Geffen School of Medicine at University of California, Los Angeles, CA90095
| | - Prabhjit Singh
- Department of Neurobiology, David Geffen School of Medicine at University of California, Los Angeles, CA90095
| | - Jeffrey M. Donlea
- Department of Neurobiology, David Geffen School of Medicine at University of California, Los Angeles, CA90095
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4
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Brown EB, Lloyd E, Martin-Peña A, McFarlane S, Dahanukar A, Keene AC. Aging is associated with a modality-specific decline in taste. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.01.578408. [PMID: 38352472 PMCID: PMC10862884 DOI: 10.1101/2024.02.01.578408] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/15/2024]
Abstract
Deficits in chemosensory processing are associated with healthy aging, as well as numerous neurodegenerative disorders, including Alzheimer's Disease (AD). In many cases, chemosensory deficits are harbingers of neurodegenerative disease, and understanding the mechanistic basis for these changes may provide insight into the fundamental dysfunction associated with aging and neurodegeneration. The fruit fly, Drosophila melanogaster , is a powerful model for studying chemosensation, aging, and aging-related pathologies, yet the effects of aging and neurodegeneration on chemosensation remain largely unexplored in this model, particularly with respect to taste. To determine whether the effects of aging on taste are conserved in flies, we compared the response of flies to different appetitive tastants. Aging impaired response to sugars, but not medium-chain fatty acids that are sensed by a shared population of neurons, revealing modality-specific deficits in taste. Selective expression of the human amyloid beta (Aβ) 1-42 peptide bearing the Arctic mutation (E693E) associated with early onset AD in the neurons that sense sugars and fatty acids phenocopies the effects of aging, suggesting that the age-related decline in response is localized to gustatory neurons. Functional imaging of gustatory axon terminals revealed reduced response to sugar, but not fatty acids. Axonal innervation of the fly taste center was largely intact in aged flies, suggesting that reduced sucrose response does not derive from neurodegeneration. Conversely, expression of the amyloid peptide in sweet-sensing taste neurons resulted in reduced innervation of the primary fly taste center. A comparison of transcript expression within the sugar-sensing taste neurons revealed age-related changes in 66 genes, including a reduction in odorant-binding protein class genes that are also expressed in taste sensilla. Together, these findings suggest that deficits in taste detection may result from signaling pathway-specific changes, while different mechanisms underly taste deficits in aged and AD model flies. Overall, this work provides a model to examine cellular deficits in neural function associated with aging and AD.
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5
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Jetti SK, Crane AB, Akbergenova Y, Aponte-Santiago NA, Cunningham KL, Whittaker CA, Littleton JT. Molecular logic of synaptic diversity between Drosophila tonic and phasic motoneurons. Neuron 2023; 111:3554-3569.e7. [PMID: 37611584 DOI: 10.1016/j.neuron.2023.07.019] [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: 01/17/2023] [Revised: 05/22/2023] [Accepted: 07/28/2023] [Indexed: 08/25/2023]
Abstract
Although neuronal subtypes display unique synaptic organization and function, the underlying transcriptional differences that establish these features are poorly understood. To identify molecular pathways that contribute to synaptic diversity, single-neuron Patch-seq RNA profiling was performed on Drosophila tonic and phasic glutamatergic motoneurons. Tonic motoneurons form weaker facilitating synapses onto single muscles, while phasic motoneurons form stronger depressing synapses onto multiple muscles. Super-resolution microscopy and in vivo imaging demonstrated that synaptic active zones in phasic motoneurons are more compact and display enhanced Ca2+ influx compared with their tonic counterparts. Genetic analysis identified unique synaptic properties that mapped onto gene expression differences for several cellular pathways, including distinct signaling ligands, post-translational modifications, and intracellular Ca2+ buffers. These findings provide insights into how unique transcriptomes drive functional and morphological differences between neuronal subtypes.
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Affiliation(s)
- Suresh K Jetti
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Andrés B Crane
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yulia Akbergenova
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Nicole A Aponte-Santiago
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Karen L Cunningham
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Charles A Whittaker
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - J Troy Littleton
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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6
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Bhattacharya D, Górska-Andrzejak J, Abaquita TAL, Pyza E. Effects of adenosine receptor overexpression and silencing in neurons and glial cells on lifespan, fitness, and sleep of Drosophila melanogaster. Exp Brain Res 2023:10.1007/s00221-023-06649-y. [PMID: 37335362 DOI: 10.1007/s00221-023-06649-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 05/28/2023] [Indexed: 06/21/2023]
Abstract
A single adenosine receptor gene (dAdoR) has been detected in Drosophila melanogaster. However, its function in different cell types of the nervous system is mostly unknown. Therefore, we overexpressed or silenced the dAdoR gene in eye photoreceptors, all neurons, or glial cells and examined the fitness of flies, the amount and daily pattern of sleep, and the influence of dAdoR silencing on Bruchpilot (BRP) presynaptic protein. Furthermore, we examined the dAdoR and brp gene expression in young and old flies. We found that a higher level of dAdoR in the retina photoreceptors, all neurons, and glial cells negatively influenced the survival rate and lifespan of male and female Drosophila in a cell-dependent manner and to a different extent depending on the age of the flies. In old flies, expression of both dAdoR and brp was higher than in young ones. An excess of dAdoR in neurons improved climbing in older individuals. It also influenced sleep by lengthening nighttime sleep and siesta. In turn, silencing of dAdoR decreased the lifespan of flies, although it increased the survival rate of young flies. It hindered the climbing of older males and females, but did not change sleep. Silencing also affected the daily pattern of BRP abundance, especially when dAdoR expression was decreased in glial cells. The obtained results indicate the role of adenosine and dAdoR in the regulation of fitness in flies that is based on communication between neurons and glial cells, and the effect of glial cells on synapses.
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Affiliation(s)
| | | | | | - Elżbieta Pyza
- Department of Cell Biology and Imaging, Jagellonian University, Kraków, Poland.
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7
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Krout M, Oh KH, Xiong A, Frankel EB, Kurshan PT, Kim H, Richmond JE. C. elegans Clarinet/CLA-1 recruits RIMB-1/RIM-binding protein and UNC-13 to orchestrate presynaptic neurotransmitter release. Proc Natl Acad Sci U S A 2023; 120:e2220856120. [PMID: 37186867 PMCID: PMC10214197 DOI: 10.1073/pnas.2220856120] [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: 12/07/2022] [Accepted: 04/05/2023] [Indexed: 05/17/2023] Open
Abstract
Synaptic transmission requires the coordinated activity of multiple synaptic proteins that are localized at the active zone (AZ). We previously identified a Caenorhabditis elegans protein named Clarinet (CLA-1) based on homology to the AZ proteins Piccolo, Rab3-interactingmolecule (RIM)/UNC-10 and Fife. At the neuromuscular junction (NMJ), cla-1 null mutants exhibit release defects that are greatly exacerbated in cla-1;unc-10 double mutants. To gain insights into the coordinated roles of CLA-1 and UNC-10, we examined the relative contributions of each to the function and organization of the AZ. Using a combination of electrophysiology, electron microscopy, and quantitative fluorescence imaging we explored the functional relationship of CLA-1 to other key AZ proteins including: RIM1, Cav2.1 channels, RIM1-binding protein, and Munc13 (C. elegans UNC-10, UNC-2, RIMB-1 and UNC-13, respectively). Our analyses show that CLA-1 acts in concert with UNC-10 to regulate UNC-2 calcium channel levels at the synapse via recruitment of RIMB-1. In addition, CLA-1 exerts a RIMB-1-independent role in the localization of the priming factor UNC-13. Thus C. elegans CLA-1/UNC-10 exhibit combinatorial effects that have overlapping design principles with other model organisms: RIM/RBP and RIM/ELKS in mouse and Fife/RIM and BRP/RBP in Drosophila. These data support a semiconserved arrangement of AZ scaffolding proteins that are necessary for the localization and activation of the fusion machinery within nanodomains for precise coupling to Ca2+ channels.
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Affiliation(s)
- Mia Krout
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL60607
| | - Kelly H. Oh
- Department of Cell Biology and Anatomy, Center for Cancer Cell Biology, Immunology, and Infection, Chicago Medical School, School of Graduate and Postdoctoral Studies, Rosalind Franklin University of Medicine and Science, North Chicago, IL60064
| | - Ame Xiong
- Department of Cell Biology and Anatomy, Center for Cancer Cell Biology, Immunology, and Infection, Chicago Medical School, School of Graduate and Postdoctoral Studies, Rosalind Franklin University of Medicine and Science, North Chicago, IL60064
| | - Elisa B. Frankel
- Department of Genetics, Albert Einstein College of Medicine, New York, NY10461
| | - Peri T. Kurshan
- Department of Genetics, Albert Einstein College of Medicine, New York, NY10461
| | - Hongkyun Kim
- Department of Genetics, Albert Einstein College of Medicine, New York, NY10461
| | - Janet E. Richmond
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL60607
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8
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Ghelani T, Escher M, Thomas U, Esch K, Lützkendorf J, Depner H, Maglione M, Parutto P, Gratz S, Matkovic-Rachid T, Ryglewski S, Walter AM, Holcman D, O‘Connor Giles K, Heine M, Sigrist SJ. Interactive nanocluster compaction of the ELKS scaffold and Cacophony Ca 2+ channels drives sustained active zone potentiation. SCIENCE ADVANCES 2023; 9:eade7804. [PMID: 36800417 PMCID: PMC9937578 DOI: 10.1126/sciadv.ade7804] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 01/17/2023] [Indexed: 06/01/2023]
Abstract
At presynaptic active zones (AZs), conserved scaffold protein architectures control synaptic vesicle (SV) release by defining the nanoscale distribution and density of voltage-gated Ca2+ channels (VGCCs). While AZs can potentiate SV release in the minutes range, we lack an understanding of how AZ scaffold components and VGCCs engage into potentiation. We here establish dynamic, intravital single-molecule imaging of endogenously tagged proteins at Drosophila AZs undergoing presynaptic homeostatic potentiation. During potentiation, the numbers of α1 VGCC subunit Cacophony (Cac) increased per AZ, while their mobility decreased and nanoscale distribution compacted. These dynamic Cac changes depended on the interaction between Cac channel's intracellular carboxyl terminus and the membrane-close amino-terminal region of the ELKS-family protein Bruchpilot, whose distribution compacted drastically. The Cac-ELKS/Bruchpilot interaction was also needed for sustained AZ potentiation. Our single-molecule analysis illustrates how the AZ scaffold couples to VGCC nanoscale distribution and dynamics to establish a state of sustained potentiation.
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Affiliation(s)
- Tina Ghelani
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
- Molecular and Theoretical Neuroscience Leibniz-Forschungs Institut für Molekulare Pharmakologie (FMP) im CharitéCrossOver (CCO) Charité–University Medicine Berlin Charité Campus Mitte, Charité Platz, 110117 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
| | - Marc Escher
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Ulrich Thomas
- Department of Cellular Neurobiology, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany
| | - Klara Esch
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Janine Lützkendorf
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Harald Depner
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Marta Maglione
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
- Institute for Chemistry and Biochemistry, SupraFAB, Freie Universität Berlin, Altensteinstr. 23a, 14195 Berlin, Germany
| | - Pierre Parutto
- Group of Applied Mathematics and Computational Biology, IBENS, Ecole Normale Superieure, Paris, France
- Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Cambridge CB2 0AH, UK
- Churchill College, University of Cambridge, Cambridge CB3 0DS, UK
| | - Scott Gratz
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Tanja Matkovic-Rachid
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Stefanie Ryglewski
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Alexander M. Walter
- Molecular and Theoretical Neuroscience Leibniz-Forschungs Institut für Molekulare Pharmakologie (FMP) im CharitéCrossOver (CCO) Charité–University Medicine Berlin Charité Campus Mitte, Charité Platz, 110117 Berlin, Germany
- Department of Neuroscience, University of Copenhagen, Copenhagen 2200, Denmark
| | - David Holcman
- Group of Applied Mathematics and Computational Biology, IBENS, Ecole Normale Superieure, Paris, France
- Churchill College, University of Cambridge, Cambridge CB3 0DS, UK
| | - Kate O‘Connor Giles
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
- Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA
| | - Martin Heine
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
- Research Group Molecular Physiology, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany
| | - Stephan J. Sigrist
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
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9
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Jetti SK, Crane AB, Akbergenova Y, Aponte-Santiago NA, Cunningham KL, Whittaker CA, Littleton JT. Molecular Logic of Synaptic Diversity Between Drosophila Tonic and Phasic Motoneurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.17.524447. [PMID: 36711745 PMCID: PMC9882338 DOI: 10.1101/2023.01.17.524447] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Although neuronal subtypes display unique synaptic organization and function, the underlying transcriptional differences that establish these features is poorly understood. To identify molecular pathways that contribute to synaptic diversity, single neuron PatchSeq RNA profiling was performed on Drosophila tonic and phasic glutamatergic motoneurons. Tonic motoneurons form weaker facilitating synapses onto single muscles, while phasic motoneurons form stronger depressing synapses onto multiple muscles. Super-resolution microscopy and in vivo imaging demonstrated synaptic active zones in phasic motoneurons are more compact and display enhanced Ca 2+ influx compared to their tonic counterparts. Genetic analysis identified unique synaptic properties that mapped onto gene expression differences for several cellular pathways, including distinct signaling ligands, post-translational modifications and intracellular Ca 2+ buffers. These findings provide insights into how unique transcriptomes drive functional and morphological differences between neuronal subtypes.
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Affiliation(s)
- Suresh K Jetti
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Andrés B Crane
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Yulia Akbergenova
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Nicole A Aponte-Santiago
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Karen L Cunningham
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Charles A Whittaker
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - J Troy Littleton
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
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10
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Cunningham KL, Littleton JT. Mechanisms controlling the trafficking, localization, and abundance of presynaptic Ca 2+ channels. Front Mol Neurosci 2023; 15:1116729. [PMID: 36710932 PMCID: PMC9880069 DOI: 10.3389/fnmol.2022.1116729] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 12/26/2022] [Indexed: 01/14/2023] Open
Abstract
Voltage-gated Ca2+ channels (VGCCs) mediate Ca2+ influx to trigger neurotransmitter release at specialized presynaptic sites termed active zones (AZs). The abundance of VGCCs at AZs regulates neurotransmitter release probability (Pr ), a key presynaptic determinant of synaptic strength. Given this functional significance, defining the processes that cooperate to establish AZ VGCC abundance is critical for understanding how these mechanisms set synaptic strength and how they might be regulated to control presynaptic plasticity. VGCC abundance at AZs involves multiple steps, including channel biosynthesis (transcription, translation, and trafficking through the endomembrane system), forward axonal trafficking and delivery to synaptic terminals, incorporation and retention at presynaptic sites, and protein recycling. Here we discuss mechanisms that control VGCC abundance at synapses, highlighting findings from invertebrate and vertebrate models.
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Affiliation(s)
- Karen L. Cunningham
- The Picower Institute for Learning and Memory, Department of Biology, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
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11
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Jin Y, Zhai RG. Presynaptic Cytomatrix Proteins. ADVANCES IN NEUROBIOLOGY 2023; 33:23-42. [PMID: 37615862 DOI: 10.1007/978-3-031-34229-5_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
The Cytomatrix Assembled at the active Zone (CAZ) of a presynaptic terminal displays electron-dense appearance and defines the center of the synaptic vesicle release. The protein constituents of CAZ are multiple-domain scaffolds that interact extensively with each other and also with an ensemble of synaptic vesicle proteins to ensure docking, fusion, and recycling. Reflecting the central roles of the active zone in synaptic transmission, CAZ proteins are highly conserved throughout evolution. As the nervous system increases complexity and diversity in types of neurons and synapses, CAZ proteins expand in the number of gene and protein isoforms and interacting partners. This chapter summarizes the discovery of the core CAZ proteins and current knowledge of their functions.
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Affiliation(s)
- Yishi Jin
- Department of Neurobiology, School of Biological Sciences, University of California San Diego, La Jolla, CA, USA.
| | - R Grace Zhai
- Department of Molecular and Cellular Pharmacology, Leonard M. Miller School of Medicine, University of Miami, Miami, FL, USA.
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12
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Huang S, Piao C, Beuschel CB, Zhao Z, Sigrist SJ. A brain-wide form of presynaptic active zone plasticity orchestrates resilience to brain aging in Drosophila. PLoS Biol 2022; 20:e3001730. [PMID: 36469518 PMCID: PMC9721493 DOI: 10.1371/journal.pbio.3001730] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 11/07/2022] [Indexed: 12/10/2022] Open
Abstract
The brain as a central regulator of stress integration determines what is threatening, stores memories, and regulates physiological adaptations across the aging trajectory. While sleep homeostasis seems to be linked to brain resilience, how age-associated changes intersect to adapt brain resilience to life history remains enigmatic. We here provide evidence that a brain-wide form of presynaptic active zone plasticity ("PreScale"), characterized by increases of active zone scaffold proteins and synaptic vesicle release factors, integrates resilience by coupling sleep, longevity, and memory during early aging of Drosophila. PreScale increased over the brain until mid-age, to then decreased again, and promoted the age-typical adaption of sleep patterns as well as extended longevity, while at the same time it reduced the ability of forming new memories. Genetic induction of PreScale also mimicked early aging-associated adaption of sleep patterns and the neuronal activity/excitability of sleep control neurons. Spermidine supplementation, previously shown to suppress early aging-associated PreScale, also attenuated the age-typical sleep pattern changes. Pharmacological induction of sleep for 2 days in mid-age flies also reset PreScale, restored memory formation, and rejuvenated sleep patterns. Our data suggest that early along the aging trajectory, PreScale acts as an acute, brain-wide form of presynaptic plasticity to steer trade-offs between longevity, sleep, and memory formation in a still plastic phase of early brain aging.
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Affiliation(s)
- Sheng Huang
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Berlin, Germany
| | - Chengji Piao
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Berlin, Germany
| | - Christine B. Beuschel
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Berlin, Germany
| | - Zhiying Zhao
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Stephan J. Sigrist
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Berlin, Germany
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13
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Muttathukunnel P, Frei P, Perry S, Dickman D, Müller M. Rapid homeostatic modulation of transsynaptic nanocolumn rings. Proc Natl Acad Sci U S A 2022; 119:e2119044119. [PMID: 36322725 PMCID: PMC9659372 DOI: 10.1073/pnas.2119044119] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 09/10/2022] [Indexed: 11/07/2022] Open
Abstract
Robust neural information transfer relies on a delicate molecular nano-architecture of chemical synapses. Neurotransmitter release is controlled by a specific arrangement of proteins within presynaptic active zones. How the specific presynaptic molecular architecture relates to postsynaptic organization and how synaptic nano-architecture is transsynaptically regulated to enable stable synaptic transmission remain enigmatic. Using time-gated stimulated emission-depletion microscopy at the Drosophila neuromuscular junction, we found that presynaptic nanorings formed by the active-zone scaffold Bruchpilot (Brp) align with postsynaptic glutamate receptor (GluR) rings. Individual rings harbor approximately four transsynaptically aligned Brp-GluR nanocolumns. Similar nanocolumn rings are formed by the presynaptic protein Unc13A and GluRs. Intriguingly, acute GluR impairment triggers transsynaptic nanocolumn formation on the minute timescale during homeostatic plasticity. We reveal distinct phases of structural transsynaptic homeostatic plasticity, with postsynaptic GluR reorganization preceding presynaptic Brp modulation. Finally, homeostatic control of transsynaptic nano-architecture and neurotransmitter release requires the auxiliary GluR subunit Neto. Thus, transsynaptic nanocolumn rings provide a substrate for rapid homeostatic stabilization of synaptic efficacy.
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Affiliation(s)
- Paola Muttathukunnel
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich/Swiss Federal Institute of Technology (ETH) Zurich, Zurich, 8057 Switzerland
| | - Patrick Frei
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Sarah Perry
- Department of Neurobiology, University of Southern California, Los Angeles, CA 90089
| | - Dion Dickman
- Department of Neurobiology, University of Southern California, Los Angeles, CA 90089
| | - Martin Müller
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich/Swiss Federal Institute of Technology (ETH) Zurich, Zurich, 8057 Switzerland
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14
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Active forgetting requires Sickie function in a dedicated dopamine circuit in Drosophila. Proc Natl Acad Sci U S A 2022; 119:e2204229119. [PMID: 36095217 PMCID: PMC9499536 DOI: 10.1073/pnas.2204229119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Forgetting is an essential component of the brain's memory management system, providing a balance to memory formation processes by removing unused or unwanted memories, or by suppressing their expression. However, the molecular, cellular, and circuit mechanisms underlying forgetting are poorly understood. Here we show that the memory suppressor gene, sickie, functions in a single dopamine neuron (DAn) by supporting the process of active forgetting in Drosophila. RNAi knockdown (KD) of sickie impairs forgetting by reducing the Ca2+ influx and DA release from the DAn that promotes forgetting. Coimmunoprecipitation/mass spectrometry analyses identified cytoskeletal and presynaptic active zone (AZ) proteins as candidates that physically interact with Sickie, and a focused RNAi screen of the candidates showed that Bruchpilot (Brp)-a presynaptic AZ protein that regulates calcium channel clustering and neurotransmitter release-impairs active forgetting like sickie KD. In addition, overexpression of brp rescued the impaired forgetting of sickie KD, providing evidence that they function in the same process. Moreover, we show that sickie KD in the DAn reduces the abundance and size of AZ markers but increases their number, suggesting that Sickie controls DAn activity for forgetting by modulating the presynaptic AZ structure. Our results identify a molecular and circuit mechanism for normal levels of active forgetting and reveal a surprising role of Sickie in maintaining presynaptic AZ structure for neurotransmitter release.
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15
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Andreani T, Rosensweig C, Sisobhan S, Ogunlana E, Kath W, Allada R. Circadian programming of the ellipsoid body sleep homeostat in Drosophila. eLife 2022; 11:e74327. [PMID: 35735904 PMCID: PMC9270026 DOI: 10.7554/elife.74327] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 06/23/2022] [Indexed: 11/18/2022] Open
Abstract
Homeostatic and circadian processes collaborate to appropriately time and consolidate sleep and wake. To understand how these processes are integrated, we scheduled brief sleep deprivation at different times of day in Drosophila and find elevated morning rebound compared to evening. These effects depend on discrete morning and evening clock neurons, independent of their roles in circadian locomotor activity. In the R5 ellipsoid body sleep homeostat, we identified elevated morning expression of activity dependent and presynaptic gene expression as well as the presynaptic protein BRUCHPILOT consistent with regulation by clock circuits. These neurons also display elevated calcium levels in response to sleep loss in the morning, but not the evening consistent with the observed time-dependent sleep rebound. These studies reveal the circuit and molecular mechanisms by which discrete circadian clock neurons program a homeostatic sleep center.
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Affiliation(s)
- Tomas Andreani
- Department of Neurobiology, Northwestern UniversityEvanstonUnited States
| | - Clark Rosensweig
- Department of Neurobiology, Northwestern UniversityEvanstonUnited States
| | - Shiju Sisobhan
- Department of Neurobiology, Northwestern UniversityEvanstonUnited States
| | - Emmanuel Ogunlana
- Department of Neurobiology, Northwestern UniversityEvanstonUnited States
| | - William Kath
- Department of Engineering Sciences and Applied Mathematics, Northwestern UniversityEvanstonUnited States
| | - Ravi Allada
- Department of Neurobiology, Northwestern UniversityChicagoUnited States
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16
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Tan C, Wang SSH, de Nola G, Kaeser PS. Rebuilding essential active zone functions within a synapse. Neuron 2022; 110:1498-1515.e8. [PMID: 35176221 PMCID: PMC9081183 DOI: 10.1016/j.neuron.2022.01.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 12/21/2021] [Accepted: 01/24/2022] [Indexed: 01/15/2023]
Abstract
Presynaptic active zones are molecular machines that control neurotransmitter secretion. They form sites for vesicle docking and priming and couple vesicles to Ca2+ entry for release triggering. The complexity of active zone machinery has made it challenging to determine its mechanisms in release. Simultaneous knockout of the active zone proteins RIM and ELKS disrupts active zone assembly, abolishes vesicle docking, and impairs release. We here rebuild docking, priming, and Ca2+ secretion coupling in these mutants without reinstating active zone networks. Re-expression of RIM zinc fingers recruited Munc13 to undocked vesicles and rendered the vesicles release competent. Action potential triggering of release was reconstituted by docking these primed vesicles to Ca2+ channels through attaching RIM zinc fingers to CaVβ4-subunits. Our work identifies an 80-kDa β4-Zn protein that bypasses the need for megadalton-sized secretory machines, establishes that fusion competence and docking are mechanistically separable, and defines RIM zinc finger-Munc13 complexes as hubs for active zone function.
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Affiliation(s)
- Chao Tan
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Shan Shan H Wang
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Giovanni de Nola
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Pascal S Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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17
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Knodel MM, Dutta Roy R, Wittum G. Influence of T-Bar on Calcium Concentration Impacting Release Probability. Front Comput Neurosci 2022; 16:855746. [PMID: 35586479 PMCID: PMC9108211 DOI: 10.3389/fncom.2022.855746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 03/09/2022] [Indexed: 11/25/2022] Open
Abstract
The relation of form and function, namely the impact of the synaptic anatomy on calcium dynamics in the presynaptic bouton, is a major challenge of present (computational) neuroscience at a cellular level. The Drosophila larval neuromuscular junction (NMJ) is a simple model system, which allows studying basic effects in a rather simple way. This synapse harbors several special structures. In particular, in opposite to standard vertebrate synapses, the presynaptic boutons are rather large, and they have several presynaptic zones. In these zones, different types of anatomical structures are present. Some of the zones bear a so-called T-bar, a particular anatomical structure. The geometric form of the T-bar resembles the shape of the letter “T” or a table with one leg. When an action potential arises, calcium influx is triggered. The probability of vesicle docking and neurotransmitter release is superlinearly proportional to the concentration of calcium close to the vesicular release site. It is tempting to assume that the T-bar causes some sort of calcium accumulation and hence triggers a higher release probability and thus enhances neurotransmitter exocytosis. In order to study this influence in a quantitative manner, we constructed a typical T-bar geometry and compared the calcium concentration close to the active zones (AZs). We compared the case of synapses with and without T-bars. Indeed, we found a substantial influence of the T-bar structure on the presynaptic calcium concentrations close to the AZs, indicating that this anatomical structure increases vesicle release probability. Therefore, our study reveals how the T-bar zone implies a strong relation between form and function. Our study answers the question of experimental studies (namely “Wichmann and Sigrist, Journal of neurogenetics 2010”) concerning the sense of the anatomical structure of the T-bar.
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Affiliation(s)
- Markus M. Knodel
- Goethe Center for Scientific Computing (GCSC), Goethe Universität Frankfurt, Frankfurt, Germany
- *Correspondence: Markus M. Knodel ; orcid.org/0000-0001-8739-0803
| | | | - Gabriel Wittum
- Goethe Center for Scientific Computing (GCSC), Goethe Universität Frankfurt, Frankfurt, Germany
- Applied Mathematics and Computational Science, Computer, Electrical and Mathematical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
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18
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Szule JA. Hypothesis Relating the Structure, Biochemistry and Function of Active Zone Material Macromolecules at a Neuromuscular Junction. Front Synaptic Neurosci 2022; 13:798225. [PMID: 35069169 PMCID: PMC8766674 DOI: 10.3389/fnsyn.2021.798225] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 12/14/2021] [Indexed: 12/22/2022] Open
Abstract
This report integrates knowledge of in situ macromolecular structures and synaptic protein biochemistry to propose a unified hypothesis for the regulation of certain vesicle trafficking events (i.e., docking, priming, Ca2+-triggering, and membrane fusion) that lead to neurotransmitter secretion from specialized “active zones” of presynaptic axon terminals. Advancements in electron tomography, to image tissue sections in 3D at nanometer scale resolution, have led to structural characterizations of a network of different classes of macromolecules at the active zone, called “Active Zone Material’. At frog neuromuscular junctions, the classes of Active Zone Material macromolecules “top-masts”, “booms”, “spars”, “ribs” and “pins” direct synaptic vesicle docking while “pins”, “ribs” and “pegs” regulate priming to influence Ca2+-triggering and membrane fusion. Other classes, “beams”, “steps”, “masts”, and “synaptic vesicle luminal filaments’ likely help organize and maintain the structural integrity of active zones. Extensive studies on the biochemistry that regulates secretion have led to comprehensive characterizations of the many conserved proteins universally involved in these trafficking events. Here, a hypothesis including a partial proteomic atlas of Active Zone Material is presented which considers the common roles, binding partners, physical features/structure, and relative positioning in the axon terminal of both the proteins and classes of macromolecules involved in the vesicle trafficking events. The hypothesis designates voltage-gated Ca2+ channels and Ca2+-gated K+ channels to ribs and pegs that are connected to macromolecules that span the presynaptic membrane at the active zone. SNARE proteins (Syntaxin, SNAP25, and Synaptobrevin), SNARE-interacting proteins Synaptotagmin, Munc13, Munc18, Complexin, and NSF are designated to ribs and/or pins. Rab3A and Rabphillin-3A are designated to top-masts and/or booms and/or spars. RIM, Bassoon, and Piccolo are designated to beams, steps, masts, ribs, spars, booms, and top-masts. Spectrin is designated to beams. Lastly, the luminal portions of SV2 are thought to form the bulk of the observed synaptic vesicle luminal filaments. The goal here is to help direct future studies that aim to bridge Active Zone Material structure, biochemistry, and function to ultimately determine how it regulates the trafficking events in vivo that lead to neurotransmitter secretion.
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19
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Graham LC, Kline RA, Lamont DJ, Gillingwater TH, Mabbott NA, Skehel PA, Wishart TM. Temporal Profiling of the Cortical Synaptic Mitochondrial Proteome Identifies Ageing Associated Regulators of Stability. Cells 2021; 10:cells10123403. [PMID: 34943911 PMCID: PMC8700124 DOI: 10.3390/cells10123403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/15/2021] [Accepted: 11/25/2021] [Indexed: 11/16/2022] Open
Abstract
Synapses are particularly susceptible to the effects of advancing age, and mitochondria have long been implicated as organelles contributing to this compartmental vulnerability. Despite this, the mitochondrial molecular cascades promoting age-dependent synaptic demise remain to be elucidated. Here, we sought to examine how the synaptic mitochondrial proteome (including strongly mitochondrial associated proteins) was dynamically and temporally regulated throughout ageing to determine whether alterations in the expression of individual candidates can influence synaptic stability/morphology. Proteomic profiling of wild-type mouse cortical synaptic and non-synaptic mitochondria across the lifespan revealed significant age-dependent heterogeneity between mitochondrial subpopulations, with aged organelles exhibiting unique protein expression profiles. Recapitulation of aged synaptic mitochondrial protein expression at the Drosophila neuromuscular junction has the propensity to perturb the synaptic architecture, demonstrating that temporal regulation of the mitochondrial proteome may directly modulate the stability of the synapse in vivo.
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Affiliation(s)
- Laura C. Graham
- The Roslin Institute, University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, UK; (L.C.G.); (R.A.K.); (N.A.M.)
- Euan MacDonald Centre, Chancellor’s Building, University of Edinburgh, 49 Little France Crescent, Edinburgh EH16 4SB, UK; (T.H.G.); (P.A.S.)
| | - Rachel A. Kline
- The Roslin Institute, University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, UK; (L.C.G.); (R.A.K.); (N.A.M.)
- Euan MacDonald Centre, Chancellor’s Building, University of Edinburgh, 49 Little France Crescent, Edinburgh EH16 4SB, UK; (T.H.G.); (P.A.S.)
| | - Douglas J. Lamont
- FingerPrints Proteomic Facility, College of Life Sciences, University of Dundee, Dow Street DD1 5EH, UK;
| | - Thomas H. Gillingwater
- Euan MacDonald Centre, Chancellor’s Building, University of Edinburgh, 49 Little France Crescent, Edinburgh EH16 4SB, UK; (T.H.G.); (P.A.S.)
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | - Neil A. Mabbott
- The Roslin Institute, University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, UK; (L.C.G.); (R.A.K.); (N.A.M.)
| | - Paul A. Skehel
- Euan MacDonald Centre, Chancellor’s Building, University of Edinburgh, 49 Little France Crescent, Edinburgh EH16 4SB, UK; (T.H.G.); (P.A.S.)
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | - Thomas M. Wishart
- The Roslin Institute, University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, UK; (L.C.G.); (R.A.K.); (N.A.M.)
- Euan MacDonald Centre, Chancellor’s Building, University of Edinburgh, 49 Little France Crescent, Edinburgh EH16 4SB, UK; (T.H.G.); (P.A.S.)
- Centre for Dementia Prevention, The University of Edinburgh, 9A Bioquarter, 9 Little France Road, Edinburgh EH16 4UX, UK
- Correspondence:
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20
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Weiss JT, Donlea JM. Sleep deprivation results in diverse patterns of synaptic scaling across the Drosophila mushroom bodies. Curr Biol 2021; 31:3248-3261.e3. [PMID: 34107302 PMCID: PMC8355077 DOI: 10.1016/j.cub.2021.05.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 03/22/2021] [Accepted: 05/11/2021] [Indexed: 11/19/2022]
Abstract
Sleep is essential for a variety of plastic processes, including learning and memory. However, the consequences of insufficient sleep on circuit connectivity remain poorly understood. To better appreciate the effects of sleep loss on synaptic connectivity across a memory-encoding circuit, we examined changes in the distribution of synaptic markers in the Drosophila mushroom body (MB). Protein-trap tags for active zone components indicate that recent sleep time is inversely correlated with Bruchpilot (BRP) abundance in the MB lobes; sleep loss elevates BRP while sleep induction reduces BRP across the MB. Overnight sleep deprivation also elevated levels of dSyd-1 and Cacophony, but not other pre-synaptic proteins. Cell-type-specific genetic reporters show that MB-intrinsic Kenyon cells (KCs) exhibit increased pre-synaptic BRP throughout the axonal lobes after sleep deprivation; similar increases were not detected in projections from large interneurons or dopaminergic neurons that innervate the MB. These results indicate that pre-synaptic plasticity in KCs is responsible for elevated levels of BRP in the MB lobes of sleep-deprived flies. Because KCs provide synaptic inputs to several classes of post-synaptic partners, we next used a fluorescent reporter for synaptic contacts to test whether each class of KC output connections is scaled uniformly by sleep loss. The KC output synapses that we observed here can be divided into three classes: KCs to MB interneurons; KCs to dopaminergic neurons; and KCs to MB output neurons. No single class showed uniform scaling across each constituent member, indicating that different rules may govern plasticity during sleep loss across cell types.
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Affiliation(s)
- Jacqueline T Weiss
- Department of Neurobiology, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095, USA; Neuroscience Interdepartmental Program, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Jeffrey M Donlea
- Department of Neurobiology, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095, USA.
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21
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Götz TWB, Puchkov D, Lysiuk V, Lützkendorf J, Nikonenko AG, Quentin C, Lehmann M, Sigrist SJ, Petzoldt AG. Rab2 regulates presynaptic precursor vesicle biogenesis at the trans-Golgi. J Cell Biol 2021; 220:211946. [PMID: 33822845 PMCID: PMC8025234 DOI: 10.1083/jcb.202006040] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 02/08/2021] [Accepted: 02/26/2021] [Indexed: 11/22/2022] Open
Abstract
Reliable delivery of presynaptic material, including active zone and synaptic vesicle proteins from neuronal somata to synaptic terminals, is prerequisite for successful synaptogenesis and neurotransmission. However, molecular mechanisms controlling the somatic assembly of presynaptic precursors remain insufficiently understood. We show here that in mutants of the small GTPase Rab2, both active zone and synaptic vesicle proteins accumulated in the neuronal cell body at the trans-Golgi and were, consequently, depleted at synaptic terminals, provoking neurotransmission deficits. Ectopic presynaptic material accumulations consisted of heterogeneous vesicles and short tubules of 40 × 60 nm, segregating in subfractions either positive for active zone or synaptic vesicle proteins and LAMP1, a lysosomal membrane protein. Genetically, Rab2 acts upstream of Arl8, a lysosomal adaptor controlling axonal export of precursors. Collectively, we identified a Golgi-associated assembly sequence of presynaptic precursor biogenesis dependent on a Rab2-regulated protein export and sorting step at the trans-Golgi.
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Affiliation(s)
- Torsten W B Götz
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany
| | - Dmytro Puchkov
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V., Campus Berlin-Buch, Berlin, Germany
| | - Veronika Lysiuk
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany
| | - Janine Lützkendorf
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany
| | | | - Christine Quentin
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany
| | - Martin Lehmann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V., Campus Berlin-Buch, Berlin, Germany
| | - Stephan J Sigrist
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany.,NeuroCure, Charité, Berlin, Germany
| | - Astrid G Petzoldt
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany
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22
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Goel P, Dickman D. Synaptic homeostats: latent plasticity revealed at the Drosophila neuromuscular junction. Cell Mol Life Sci 2021; 78:3159-3179. [PMID: 33449150 PMCID: PMC8044042 DOI: 10.1007/s00018-020-03732-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/19/2020] [Accepted: 12/04/2020] [Indexed: 12/11/2022]
Abstract
Homeostatic signaling systems are fundamental forms of biological regulation that maintain stable functionality in a changing environment. In the nervous system, synapses are crucial substrates for homeostatic modulation, serving to establish, maintain, and modify the balance of excitation and inhibition. Synapses must be sufficiently flexible to enable the plasticity required for learning and memory but also endowed with the stability to last a lifetime. In response to the processes of development, growth, remodeling, aging, and disease that challenge synapses, latent forms of adaptive plasticity become activated to maintain synaptic stability. In recent years, new insights into the homeostatic control of synaptic function have been achieved using the powerful Drosophila neuromuscular junction (NMJ). This review will focus on work over the past 10 years that has illuminated the cellular and molecular mechanisms of five homeostats that operate at the fly NMJ. These homeostats adapt to loss of postsynaptic neurotransmitter receptor functionality, glutamate imbalance, axonal injury, as well as aberrant synaptic growth and target innervation. These diverse homeostats work independently yet can be simultaneously expressed to balance neurotransmission. Growing evidence from this model glutamatergic synapse suggests these ancient homeostatic signaling systems emerged early in evolution and are fundamental forms of plasticity that also function to stabilize mammalian cholinergic NMJs and glutamatergic central synapses.
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Affiliation(s)
- Pragya Goel
- Department of Neurobiology, University of Southern California, Los Angeles, CA, 90089, USA
| | - Dion Dickman
- Department of Neurobiology, University of Southern California, Los Angeles, CA, 90089, USA.
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23
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Bhat SA, Yousuf A, Mushtaq Z, Kumar V, Qurashi A. Fragile X Premutation rCGG Repeats Impair Synaptic Growth and Synaptic Transmission at Drosophila larval Neuromuscular Junction. Hum Mol Genet 2021; 30:1677-1692. [PMID: 33772546 DOI: 10.1093/hmg/ddab087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/21/2021] [Accepted: 03/22/2021] [Indexed: 11/14/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disease that develops in some premutation (PM) carriers of the FMR1 gene with alleles bearing 55-200 CGG repeats. The discovery of a broad spectrum of clinical and cell developmental abnormalities among PM carriers with or without FXTAS and in model systems suggests that neurodegeneration seen in FXTAS could be the inevitable end-result of pathophysiological processes set during early development. Hence, it is imperative to trace early PM-induced pathological abnormalities. Previous studies have shown that transgenic Drosophila carrying PM-length CGG repeats are sufficient to cause neurodegeneration. Here, we used the same transgenic model to understand the effect of CGG repeats on the structure and function of the developing nervous system. We show that presynaptic expression of CGG repeats restricts synaptic growth, reduces the number of synaptic boutons, leads to aberrant presynaptic varicosities, and impairs synaptic transmission at the larval neuromuscular junctions. The postsynaptic analysis shows that both glutamate receptors and subsynaptic reticulum proteins were normal. However, a high percentage of boutons show a reduced density of Bruchpilot protein, a key component of presynaptic active zones required for vesicle release. The electrophysiological analysis shows a significant reduction in quantal content, a measure of total synaptic vesicles released per excitation potential. Together, these findings suggest that synapse perturbation caused by rCGG repeats mediates presynaptically during larval NMJ development. We also suggest that the stress-activated c-Jun N-terminal kinase protein Basket and CIDE-N protein Drep-2 positively mediate Bruchpilot active zone defects caused by rCGG repeats.
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Affiliation(s)
- Sajad A Bhat
- Department of Biotechnology, University of Kashmir, Srinagar, JK, 190006, India
| | - Aadil Yousuf
- Department of Biotechnology, University of Kashmir, Srinagar, JK, 190006, India
| | - Zeeshan Mushtaq
- Laboratory of Neurogenetics, IISER-Bhopal, Bhopal, MP, 462066, India
| | - Vimlesh Kumar
- Laboratory of Neurogenetics, IISER-Bhopal, Bhopal, MP, 462066, India
| | - Abrar Qurashi
- Department of Biotechnology, University of Kashmir, Srinagar, JK, 190006, India
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24
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Petzoldt AG, Götz TWB, Driller JH, Lützkendorf J, Reddy-Alla S, Matkovic-Rachid T, Liu S, Knoche E, Mertel S, Ugorets V, Lehmann M, Ramesh N, Beuschel CB, Kuropka B, Freund C, Stelzl U, Loll B, Liu F, Wahl MC, Sigrist SJ. RIM-binding protein couples synaptic vesicle recruitment to release sites. J Cell Biol 2021; 219:151735. [PMID: 32369542 PMCID: PMC7337501 DOI: 10.1083/jcb.201902059] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 02/03/2020] [Accepted: 04/07/2020] [Indexed: 11/24/2022] Open
Abstract
At presynaptic active zones, arrays of large conserved scaffold proteins mediate fast and temporally precise release of synaptic vesicles (SVs). SV release sites could be identified by clusters of Munc13, which allow SVs to dock in defined nanoscale relation to Ca2+ channels. We here show in Drosophila that RIM-binding protein (RIM-BP) connects release sites physically and functionally to the ELKS family Bruchpilot (BRP)-based scaffold engaged in SV recruitment. The RIM-BP N-terminal domain, while dispensable for SV release site organization, was crucial for proper nanoscale patterning of the BRP scaffold and needed for SV recruitment of SVs under strong stimulation. Structural analysis further showed that the RIM-BP fibronectin domains form a “hinge” in the protein center, while the C-terminal SH3 domain tandem binds RIM, Munc13, and Ca2+ channels release machinery collectively. RIM-BPs’ conserved domain architecture seemingly provides a relay to guide SVs from membrane far scaffolds into membrane close release sites.
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Affiliation(s)
- Astrid G Petzoldt
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany
| | - Torsten W B Götz
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany
| | - Jan Heiner Driller
- Freie Universität Berlin, Institute of Chemistry and Biochemistry/Structural Biochemistry Berlin, Berlin, Germany
| | - Janine Lützkendorf
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany
| | - Suneel Reddy-Alla
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany
| | | | - Sunbin Liu
- Freie Universität Berlin, Institute of Chemistry and Biochemistry/Structural Biochemistry Berlin, Berlin, Germany
| | - Elena Knoche
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany
| | - Sara Mertel
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany
| | - Vladimir Ugorets
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany
| | - Martin Lehmann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V., Campus Berlin-Buch, Berlin, Germany
| | - Niraja Ramesh
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany
| | | | - Benno Kuropka
- Universität Berlin, Institute for Chemistry and Biochemistry, Berlin, Germany
| | - Christian Freund
- Universität Berlin, Institute for Chemistry and Biochemistry, Berlin, Germany
| | - Ulrich Stelzl
- Institut für Pharmazeutische Wissenschaften, Graz, Austria
| | - Bernhard Loll
- Freie Universität Berlin, Institute of Chemistry and Biochemistry/Structural Biochemistry Berlin, Berlin, Germany
| | - Fan Liu
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V., Campus Berlin-Buch, Berlin, Germany
| | - Markus C Wahl
- Freie Universität Berlin, Institute of Chemistry and Biochemistry/Structural Biochemistry Berlin, Berlin, Germany.,Helmholtz-Zentrum Berlin für Materialien und Energie, Macromolecular Crystallography, Berlin, Germany
| | - Stephan J Sigrist
- Freie Universität Berlin, Institute for Biology and Genetics, Berlin, Germany.,NeuroCure, Charité, Berlin, Germany
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25
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Rizalar FS, Roosen DA, Haucke V. A Presynaptic Perspective on Transport and Assembly Mechanisms for Synapse Formation. Neuron 2020; 109:27-41. [PMID: 33098763 DOI: 10.1016/j.neuron.2020.09.038] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/26/2020] [Accepted: 09/25/2020] [Indexed: 01/01/2023]
Abstract
Neurons are highly polarized cells with a single axon and multiple dendrites derived from the cell body to form tightly associated pre- and postsynaptic compartments. As the biosynthetic machinery is largely restricted to the somatodendritic domain, the vast majority of presynaptic components are synthesized in the neuronal soma, packaged into synaptic precursor vesicles, and actively transported along the axon to sites of presynaptic biogenesis. In contrast with the significant progress that has been made in understanding synaptic transmission and processing of information at the post-synapse, comparably little is known about the formation and dynamic remodeling of the presynaptic compartment. We review here our current understanding of the mechanisms that govern the biogenesis, transport, and assembly of the key components for presynaptic neurotransmission, discuss how alterations in presynaptic assembly may impact nervous system function or lead to disease, and outline key open questions for future research.
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Affiliation(s)
- Filiz Sila Rizalar
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Dorien A Roosen
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany; Faculty of Biology, Chemistry, Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany.
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26
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Damulewicz M, Woźnicka O, Jasińska M, Pyza E. CRY-dependent plasticity of tetrad presynaptic sites in the visual system of Drosophila at the morning peak of activity and sleep. Sci Rep 2020; 10:18161. [PMID: 33097794 PMCID: PMC7585400 DOI: 10.1038/s41598-020-74442-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 09/22/2020] [Indexed: 11/09/2022] Open
Abstract
Tetrad synapses are formed between the retina photoreceptor terminals and postsynaptic cells in the first optic neuropil (lamina) of Drosophila. They are remodelled in the course of the day and show distinct functional changes during activity and sleep. These changes result from fast degradation of the presynaptic scaffolding protein Bruchpilot (BRP) by Cryptochrome (CRY) in the morning and depend on BRP-170, one of two BRP isoforms. This process also affects the number of synaptic vesicles, both clear and dense-core, delivered to the presynaptic elements. In cry01 mutants lacking CRY and in brpΔ170, the number of synaptic vesicles is lower in the morning peak of activity than during night-sleep while in wild-type flies the number of synaptic vesicles is similar at these two time points. CRY may also set phase of the circadian rhythm in plasticity of synapses. The process of synapse remodelling stimulates the formation of clear synaptic vesicles in the morning. They carry histamine, a neurotransmitter in tetrad synapses and seem to be formed from glial capitate projections inside the photoreceptor terminals. In turn dense-core vesicles probably carry synaptic proteins building the tetrad presynaptic element.
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Affiliation(s)
- Milena Damulewicz
- Department of Cell Biology and Imaging, Institute of Zoology and Biomedical Research, Jagiellonian University, Kraków, Poland
| | - Olga Woźnicka
- Department of Cell Biology and Imaging, Institute of Zoology and Biomedical Research, Jagiellonian University, Kraków, Poland
| | - Małgorzata Jasińska
- Department of Histology, Jagiellonian University Medical College, Kraków, Poland
| | - Elżbieta Pyza
- Department of Cell Biology and Imaging, Institute of Zoology and Biomedical Research, Jagiellonian University, Kraków, Poland.
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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: 27] [Impact Index Per Article: 6.8] [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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Huang S, Piao C, Beuschel CB, Götz T, Sigrist SJ. Presynaptic Active Zone Plasticity Encodes Sleep Need in Drosophila. Curr Biol 2020; 30:1077-1091.e5. [PMID: 32142702 DOI: 10.1016/j.cub.2020.01.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 09/26/2019] [Accepted: 01/07/2020] [Indexed: 01/04/2023]
Abstract
Sleep is universal across species and essential for quality of life and health, as evidenced by the consequences of sleep loss. Sleep might homeostatically normalize synaptic gains made over wake states in order to reset information processing and storage and support learning, and sleep-associated synaptic (ultra)structural changes have been demonstrated recently. However, causal relationships between the molecular and (ultra)structural status of synapses, sleep homeostatic regulation, and learning processes have yet to be established. We show here that the status of the presynaptic active zone can directly control sleep in Drosophila. Short sleep mutants showed a brain-wide upregulation of core presynaptic scaffold proteins and release factors. Increasing the gene copy number of ELKS-family scaffold master organizer Bruchpilot (BRP) not only mimicked changes in the active zone scaffold and release proteins but importantly provoked sleep in a dosage-dependent manner, qualitatively and quantitatively reminiscent of sleep deprivation effects. Conversely, reducing the brp copy number decreased sleep in short sleep mutant backgrounds, suggesting a specific role of the active zone plasticity in homeostatic sleep regulation. Finally, elimination of BRP specifically in the sleep-promoting R2 neurons of 4xBRP animals partially restored sleep patterns and rescued learning deficits. Our results suggest that the presynaptic active zone plasticity driven by BRP operates as a sleep homeostatic actuator that also restricts periods of effective learning.
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Affiliation(s)
- Sheng Huang
- Institute for Biology/Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany; NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
| | - Chengji Piao
- Institute for Biology/Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Christine B Beuschel
- Institute for Biology/Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Torsten Götz
- Institute for Biology/Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Stephan J Sigrist
- Institute for Biology/Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany; NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany.
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29
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Structural Remodeling of Active Zones Is Associated with Synaptic Homeostasis. J Neurosci 2020; 40:2817-2827. [PMID: 32122953 DOI: 10.1523/jneurosci.2002-19.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 02/16/2020] [Accepted: 02/22/2020] [Indexed: 02/07/2023] Open
Abstract
Perturbations to postsynaptic glutamate receptors (GluRs) trigger retrograde signaling to precisely increase presynaptic neurotransmitter release, maintaining stable levels of synaptic strength, a process referred to as homeostatic regulation. However, the structural change of homeostatic regulation remains poorly defined. At wild-type Drosophila neuromuscular junction synapse, there is one Bruchpilot (Brp) ring detected by superresolution microscopy at active zones (AZs). In the present study, we report multiple Brp rings (i.e., multiple T-bars seen by electron microscopy) at AZs of both male and female larvae when GluRs are reduced. At GluRIIC-deficient neuromuscular junctions, quantal size was reduced but quantal content was increased, indicative of homeostatic presynaptic potentiation. Consistently, multiple Brp rings at AZs were observed in the two classic synaptic homeostasis models (i.e., GluRIIA mutant and pharmacological blockade of GluRIIA activity). Furthermore, postsynaptic overexpression of the cell adhesion protein Neuroligin 1 partially rescued multiple Brp rings phenotype. Our study thus supports that the formation of multiple Brp rings at AZs might be a structural basis for synaptic homeostasis.SIGNIFICANCE STATEMENT Synaptic homeostasis is a conserved fundamental mechanism to maintain efficient neurotransmission of neural networks. Active zones (AZs) are characterized by an electron-dense cytomatrix, which is largely composed of Bruchpilot (Brp) at the Drosophila neuromuscular junction synapses. It is not clear how the structure of AZs changes during homeostatic regulation. To address this question, we examined the structure of AZs by superresolution microscopy and electron microscopy during homeostatic regulation. Our results reveal multiple Brp rings at AZs of glutamate receptor-deficient neuromuscular junction synapses compared with single Brp ring at AZs in wild type (WT). We further show that Neuroligin 1-mediated retrograde signaling regulates multiple Brp ring formation at glutamate receptor-deficient synapses. This study thus reveals a regulatory mechanism for synaptic homeostasis.
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30
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Kobbersmed JR, Grasskamp AT, Jusyte M, Böhme MA, Ditlevsen S, Sørensen JB, Walter AM. Rapid regulation of vesicle priming explains synaptic facilitation despite heterogeneous vesicle:Ca 2+ channel distances. eLife 2020; 9:51032. [PMID: 32077852 PMCID: PMC7145420 DOI: 10.7554/elife.51032] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 02/14/2020] [Indexed: 12/27/2022] Open
Abstract
Chemical synaptic transmission relies on the Ca2+-induced fusion of transmitter-laden vesicles whose coupling distance to Ca2+ channels determines synaptic release probability and short-term plasticity, the facilitation or depression of repetitive responses. Here, using electron- and super-resolution microscopy at the Drosophila neuromuscular junction we quantitatively map vesicle:Ca2+ channel coupling distances. These are very heterogeneous, resulting in a broad spectrum of vesicular release probabilities within synapses. Stochastic simulations of transmitter release from vesicles placed according to this distribution revealed strong constraints on short-term plasticity; particularly facilitation was difficult to achieve. We show that postulated facilitation mechanisms operating via activity-dependent changes of vesicular release probability (e.g. by a facilitation fusion sensor) generate too little facilitation and too much variance. In contrast, Ca2+-dependent mechanisms rapidly increasing the number of releasable vesicles reliably reproduce short-term plasticity and variance of synaptic responses. We propose activity-dependent inhibition of vesicle un-priming or release site activation as novel facilitation mechanisms. Cells in the nervous system of all animals communicate by releasing and sensing chemicals at contact points named synapses. The ‘talking’ (or pre-synaptic) cell stores the chemicals close to the synapse, in small spheres called vesicles. When the cell is activated, calcium ions flow in and interact with the release-ready vesicles, which then spill the chemicals into the synapse. In turn, the ‘listening’ (or post-synaptic) cell can detect the chemicals and react accordingly. When the pre-synaptic cell is activated many times in a short period, it can release a greater quantity of chemicals, allowing a bigger reaction in the post-synaptic cell. This phenomenon is known as facilitation, but it is still unclear how exactly it can take place. This is especially the case when many of the vesicles are not ready to respond, for example when they are too far from where calcium flows into the cell. Computer simulations have been created to model facilitation but they have assumed that all vesicles are placed at the same distance to the calcium entry point: Kobbersmed et al. now provide evidence that this assumption is incorrect. Two high-resolution imaging techniques were used to measure the actual distances between the vesicles and the calcium source in the pre-synaptic cells of fruit flies: this showed that these distances are quite variable – some vesicles sit much closer to the source than others. This information was then used to create a new computer model to simulate facilitation. The results from this computing work led Kobbersmed et al. to suggest that facilitation may take place because a calcium-based mechanism in the cell increases the number of vesicles ready to release their chemicals. This new model may help researchers to better understand how the cells in the nervous system work. Ultimately, this can guide experiments to investigate what happens when information processing at synapses breaks down, for example in diseases such as epilepsy.
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Affiliation(s)
- Janus Rl Kobbersmed
- Department of Mathematical Sciences, University of Copenhagen, København, Denmark.,Department of Neuroscience, University of Copenhagen, København, Denmark
| | - Andreas T Grasskamp
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, FMP im CharitéCrossOver, Berlin, Germany
| | - Meida Jusyte
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, FMP im CharitéCrossOver, Berlin, Germany.,Einstein Center for Neuroscience, Berlin, Germany
| | - Mathias A Böhme
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, FMP im CharitéCrossOver, Berlin, Germany
| | - Susanne Ditlevsen
- Department of Mathematical Sciences, University of Copenhagen, København, Denmark
| | | | - Alexander M Walter
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, FMP im CharitéCrossOver, Berlin, Germany.,Einstein Center for Neuroscience, Berlin, Germany
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31
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Li X, Goel P, Wondolowski J, Paluch J, Dickman D. A Glutamate Homeostat Controls the Presynaptic Inhibition of Neurotransmitter Release. Cell Rep 2019; 23:1716-1727. [PMID: 29742428 PMCID: PMC5973541 DOI: 10.1016/j.celrep.2018.03.130] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 01/24/2018] [Accepted: 03/28/2018] [Indexed: 02/07/2023] Open
Abstract
We have interrogated the synaptic dialog that enables the bi-directional, homeostatic control of pre-synaptic efficacy at the glutamatergic Drosophila neuromuscular junction (NMJ). We find that homeo-static depression and potentiation use disparate genetic, induction, and expression mechanisms. Specifically, homeostatic potentiation is achieved through reduced CaMKII activity postsynaptically and increased abundance of active zone material presynaptically at one of the two neuronal subtypes innervating the NMJ, while homeostatic depression occurs without alterations in CaMKII activity and is expressed at both neuronal subtypes. Furthermore, homeostatic depression is only induced through excess presynaptic glutamate release and operates with disregard to the postsynaptic response. We propose that two independent homeostats modulate presynaptic efficacy at the Drosophila NMJ: one is an intercellular signaling system that potentiates synaptic strength following diminished postsynaptic excitability, while the other adaptively modulates presynaptic glutamate release through an autocrine mechanism without feedback from the postsynaptic compartment.
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Affiliation(s)
- Xiling Li
- Department of Neurobiology, University of Southern California, Los Angeles, CA; USC Neuroscience Graduate Program, University of Southern California, Los Angeles, CA
| | - Pragya Goel
- Department of Neurobiology, University of Southern California, Los Angeles, CA; USC Graduate Program in Molecular and Computational Biology, University of Southern California, Los Angeles, CA
| | - Joyce Wondolowski
- Department of Neurobiology, University of Southern California, Los Angeles, CA
| | - Jeremy Paluch
- Department of Neurobiology, University of Southern California, Los Angeles, CA
| | - Dion Dickman
- Department of Neurobiology, University of Southern California, Los Angeles, CA.
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32
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Goel P, Dufour Bergeron D, Böhme MA, Nunnelly L, Lehmann M, Buser C, Walter AM, Sigrist SJ, Dickman D. Homeostatic scaling of active zone scaffolds maintains global synaptic strength. J Cell Biol 2019; 218:1706-1724. [PMID: 30914419 PMCID: PMC6504899 DOI: 10.1083/jcb.201807165] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 12/14/2018] [Accepted: 03/06/2019] [Indexed: 12/23/2022] Open
Abstract
Synaptic terminals grow and retract throughout life, yet synaptic strength is maintained within stable physiological ranges. To study this process, we investigated Drosophila endophilin (endo) mutants. Although active zone (AZ) number is doubled in endo mutants, a compensatory reduction in their size homeostatically adjusts global neurotransmitter output to maintain synaptic strength. We find an inverse adaptation in rab3 mutants. Additional analyses using confocal, STED, and electron microscopy reveal a stoichiometric tuning of AZ scaffolds and nanoarchitecture. Axonal transport of synaptic cargo via the lysosomal kinesin adapter Arl8 regulates AZ abundance to modulate global synaptic output and sustain the homeostatic potentiation of neurotransmission. Finally, we find that this AZ scaling can interface with two independent homeostats, depression and potentiation, to remodel AZ structure and function, demonstrating a robust balancing of separate homeostatic adaptations. Thus, AZs are pliable substrates with elastic and modular nanostructures that can be dynamically sculpted to stabilize and tune both local and global synaptic strength.
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Affiliation(s)
- Pragya Goel
- Department of Neurobiology, University of Southern California, Los Angeles, CA
| | | | - Mathias A Böhme
- Neurocure Cluster of Excellence, Charité Universitätsmedizin, Berlin, Germany
| | - Luke Nunnelly
- Department of Neurobiology, University of Southern California, Los Angeles, CA
| | - Martin Lehmann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | | | - Alexander M Walter
- Neurocure Cluster of Excellence, Charité Universitätsmedizin, Berlin, Germany
| | | | - Dion Dickman
- Department of Neurobiology, University of Southern California, Los Angeles, CA
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33
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A Screen for Synaptic Growth Mutants Reveals Mechanisms That Stabilize Synaptic Strength. J Neurosci 2019; 39:4051-4065. [PMID: 30902873 DOI: 10.1523/jneurosci.2601-18.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 03/12/2019] [Accepted: 03/14/2019] [Indexed: 01/28/2023] Open
Abstract
Synapses grow, prune, and remodel throughout development, experience, and disease. This structural plasticity can destabilize information transfer in the nervous system. However, neural activity remains stable throughout life, implying that adaptive countermeasures exist that maintain neurotransmission within proper physiological ranges. Aberrant synaptic structure and function have been associated with a variety of neural diseases, including Fragile X syndrome, autism, and intellectual disability. We have screened 300 mutants in Drosophila larvae of both sexes for defects in synaptic growth at the neuromuscular junction, identifying 12 mutants with severe reductions or enhancements in synaptic growth. Remarkably, electrophysiological recordings revealed that synaptic strength was unchanged in all but one of these mutants compared with WT. We used a combination of genetic, anatomical, and electrophysiological analyses to illuminate three mechanisms that stabilize synaptic strength despite major disparities in synaptic growth. These include compensatory changes in (1) postsynaptic neurotransmitter receptor abundance, (2) presynaptic morphology, and (3) active zone structure. Together, this characterization identifies new mutants with defects in synaptic growth and the adaptive strategies used by synapses to homeostatically stabilize neurotransmission in response.SIGNIFICANCE STATEMENT This study reveals compensatory mechanisms used by synapses to ensure stable functionality during severe alterations in synaptic growth using the neuromuscular junction of Drosophila melanogaster as a model system. Through a forward genetic screen, we identify mutants that exhibit dramatic undergrown or overgrown synapses yet express stable levels of synaptic strength, with three specific compensatory mechanisms discovered. Thus, this study reveals novel insights into the adaptive strategies that constrain neurotransmission within narrow physiological ranges while allowing considerable flexibility in overall synapse number. More broadly, these findings provide insights into how stable synaptic function may be maintained in the nervous system during periods of intensive synaptic growth, pruning, and remodeling.
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34
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Driller JH, Lützkendorf J, Depner H, Siebert M, Kuropka B, Weise C, Piao C, Petzoldt AG, Lehmann M, Stelzl U, Zahedi R, Sickmann A, Freund C, Sigrist SJ, Wahl MC. Phosphorylation of the Bruchpilot N-terminus in Drosophila unlocks axonal transport of active zone building blocks. J Cell Sci 2019; 132:jcs.225151. [PMID: 30745339 DOI: 10.1242/jcs.225151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 01/24/2019] [Indexed: 01/31/2023] Open
Abstract
Protein scaffolds at presynaptic active zone membranes control information transfer at synapses. For scaffold biogenesis and maintenance, scaffold components must be safely transported along axons. A spectrum of kinases has been suggested to control transport of scaffold components, but direct kinase-substrate relationships and operational principles steering phosphorylation-dependent active zone protein transport are presently unknown. Here, we show that extensive phosphorylation of a 150-residue unstructured region at the N-terminus of the highly elongated Bruchpilot (BRP) active zone protein is crucial for ordered active zone precursor transport in Drosophila Point mutations that block SRPK79D kinase-mediated phosphorylation of the BRP N-terminus interfered with axonal transport, leading to BRP-positive axonal aggregates that also contain additional active zone scaffold proteins. Axonal aggregates formed only in the presence of non-phosphorylatable BRP isoforms containing the SRPK79D-targeted N-terminal stretch. We assume that specific active zone proteins are pre-assembled in transport packages and are thus co-transported as functional scaffold building blocks. Our results suggest that transient post-translational modification of a discrete unstructured domain of the master scaffold component BRP blocks oligomerization of these building blocks during their long-range transport.
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Affiliation(s)
- Jan H Driller
- Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 6, D-14195 Berlin, Germany
| | - Janine Lützkendorf
- Laboratory of Genetics, Institute of Biology, Freie Universität Berlin, Takustraße 6, D-14195 Berlin, Germany
| | - Harald Depner
- Laboratory of Genetics, Institute of Biology, Freie Universität Berlin, Takustraße 6, D-14195 Berlin, Germany
| | - Matthias Siebert
- Laboratory of Genetics, Institute of Biology, Freie Universität Berlin, Takustraße 6, D-14195 Berlin, Germany
| | - Benno Kuropka
- Laboratory of Protein Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, D-14195 Berlin, Germany
| | - Christoph Weise
- Laboratory of Protein Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, D-14195 Berlin, Germany
| | - Chengji Piao
- Laboratory of Genetics, Institute of Biology, Freie Universität Berlin, Takustraße 6, D-14195 Berlin, Germany
| | - Astrid G Petzoldt
- Laboratory of Genetics, Institute of Biology, Freie Universität Berlin, Takustraße 6, D-14195 Berlin, Germany.,NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Martin Lehmann
- Cellular Imaging, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, D-13125 Berlin, Germany
| | - Ulrich Stelzl
- Pharmaceutical Chemistry, Institute of Pharmaceutical Sciences, University of Graz, Universitätsplatz 1/I, A-8010 Graz, Austria
| | - René Zahedi
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Bunsen-Kirchhoff-Straße 11, D-44139 Dortmund, Germany
| | - Albert Sickmann
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Bunsen-Kirchhoff-Straße 11, D-44139 Dortmund, Germany
| | - Christian Freund
- Laboratory of Protein Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, D-14195 Berlin, Germany
| | - Stephan J Sigrist
- Laboratory of Genetics, Institute of Biology, Freie Universität Berlin, Takustraße 6, D-14195 Berlin, Germany .,NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Markus C Wahl
- Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 6, D-14195 Berlin, Germany .,Macromolecular Crystallography, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
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35
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Held RG, Kaeser PS. ELKS active zone proteins as multitasking scaffolds for secretion. Open Biol 2019; 8:rsob.170258. [PMID: 29491150 PMCID: PMC5830537 DOI: 10.1098/rsob.170258] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Accepted: 02/06/2018] [Indexed: 12/18/2022] Open
Abstract
Synaptic vesicle exocytosis relies on the tethering of release ready vesicles close to voltage-gated Ca2+ channels and specific lipids at the future site of fusion. This enables rapid and efficient neurotransmitter secretion during presynaptic depolarization by an action potential. Extensive research has revealed that this tethering is mediated by an active zone, a protein dense structure that is attached to the presynaptic plasma membrane and opposed to postsynaptic receptors. Although roles of individual active zone proteins in exocytosis are in part understood, the molecular mechanisms that hold the protein scaffold at the active zone together and link it to the presynaptic plasma membrane have remained unknown. This is largely due to redundancy within and across scaffolding protein families at the active zone. Recent studies, however, have uncovered that ELKS proteins, also called ERC, Rab6IP2 or CAST, act as active zone scaffolds redundant with RIMs. This redundancy has led to diverse synaptic phenotypes in studies of ELKS knockout mice, perhaps because different synapses rely to a variable extent on scaffolding redundancy. In this review, we first evaluate the need for presynaptic scaffolding, and we then discuss how the diverse synaptic and non-synaptic functional roles of ELKS support the hypothesis that ELKS provides molecular scaffolding for organizing vesicle traffic at the presynaptic active zone and in other cellular compartments.
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Affiliation(s)
- Richard G Held
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Pascal S Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
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36
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Ghelani T, Sigrist SJ. Coupling the Structural and Functional Assembly of Synaptic Release Sites. Front Neuroanat 2018; 12:81. [PMID: 30386217 PMCID: PMC6198076 DOI: 10.3389/fnana.2018.00081] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 09/18/2018] [Indexed: 01/04/2023] Open
Abstract
Information processing in our brains depends on the exact timing of calcium (Ca2+)-activated exocytosis of synaptic vesicles (SVs) from unique release sites embedded within the presynaptic active zones (AZs). While AZ scaffolding proteins obviously provide an efficient environment for release site function, the molecular design creating such release sites had remained unknown for a long time. Recent advances in visualizing the ultrastructure and topology of presynaptic protein architectures have started to elucidate how scaffold proteins establish “nanodomains” that connect voltage-gated Ca2+ channels (VGCCs) physically and functionally with release-ready SVs. Scaffold proteins here seem to operate as “molecular rulers or spacers,” regulating SV-VGCC physical distances within tens of nanometers and, thus, influence the probability and plasticity of SV release. A number of recent studies at Drosophila and mammalian synapses show that the stable positioning of discrete clusters of obligate release factor (M)Unc13 defines the position of SV release sites, and the differential expression of (M)Unc13 isoforms at synapses can regulate SV-VGCC coupling. We here review the organization of matured AZ scaffolds concerning their intrinsic organization and role for release site formation. Moreover, we also discuss insights into the developmental sequence of AZ assembly, which often entails a tightening between VGCCs and SV release sites. The findings discussed here are retrieved from vertebrate and invertebrate preparations and include a spectrum of methods ranging from cell biology, super-resolution light and electron microscopy to biophysical and electrophysiological analysis. Our understanding of how the structural and functional organization of presynaptic AZs are coupled has matured, as these processes are crucial for the understanding of synapse maturation and plasticity, and, thus, accurate information transfer and storage at chemical synapses.
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Affiliation(s)
- Tina Ghelani
- Faculty of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Stephan J Sigrist
- Faculty of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin, Germany.,NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany
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37
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Michels B, Zwaka H, Bartels R, Lushchak O, Franke K, Endres T, Fendt M, Song I, Bakr M, Budragchaa T, Westermann B, Mishra D, Eschbach C, Schreyer S, Lingnau A, Vahl C, Hilker M, Menzel R, Kähne T, Leßmann V, Dityatev A, Wessjohann L, Gerber B. Memory enhancement by ferulic acid ester across species. SCIENCE ADVANCES 2018; 4:eaat6994. [PMID: 30417089 PMCID: PMC6224069 DOI: 10.1126/sciadv.aat6994] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 09/12/2018] [Indexed: 06/09/2023]
Abstract
Cognitive impairments can be devastating for quality of life, and thus, preventing or counteracting them is of great value. To this end, the present study exploits the potential of the plant Rhodiola rosea and identifies the constituent ferulic acid eicosyl ester [icosyl-(2E)-3-(4-hydroxy-3-methoxyphenyl)-prop-2-enoate (FAE-20)] as a memory enhancer. We show that food supplementation with dried root material from R. rosea dose-dependently improves odor-taste reward associative memory scores in larval Drosophila and prevents the age-related decline of this appetitive memory in adult flies. Task-relevant sensorimotor faculties remain unaltered. From a parallel approach, a list of candidate compounds has been derived, including R. rosea-derived FAE-20. Here, we show that both R. rosea-derived FAE-20 and synthetic FAE-20 are effective as memory enhancers in larval Drosophila. Synthetic FAE-20 also partially compensates for age-related memory decline in adult flies, as well as genetically induced early-onset loss of memory function in young flies. Furthermore, it increases excitability in mouse hippocampal CA1 neurons, leads to more stable context-shock aversive associative memory in young adult (3-month-old) mice, and increases memory scores in old (>2-year-old) mice. Given these effects, and given the utility of R. rosea-the plant from which we discovered FAE-20-as a memory enhancer, these results may hold potential for clinical applications.
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Affiliation(s)
- Birgit Michels
- Leibniz Institute for Neurobiology, Department Genetics of Learning and Memory, Magdeburg, Germany
| | - Hanna Zwaka
- Leibniz Institute for Neurobiology, Department Genetics of Learning and Memory, Magdeburg, Germany
- Free University Berlin, Institute of Neurobiology, Berlin, Germany
| | - Ruth Bartels
- Free University Berlin, Institute of Neurobiology, Berlin, Germany
| | - Oleh Lushchak
- Precarpathian National University, Department of Biochemistry, Ivano-Frankivsk, Ukraine
| | - Katrin Franke
- Leibniz Institute of Plant Biochemistry (IPB), Department of Bioorganic Chemistry, Halle (Saale), Germany
| | - Thomas Endres
- Otto von Guericke University, Medical Faculty, Magdeburg, Germany
| | - Markus Fendt
- Otto von Guericke University, Medical Faculty, Institute for Pharmacology and Toxicology, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Otto von Guericke University, Magdeburg, Germany
| | - Inseon Song
- German Center for Neurodegenerative Diseases (DZNE), Molecular Neuroplasticity Group, Magdeburg, Germany
| | - May Bakr
- German Center for Neurodegenerative Diseases (DZNE), Molecular Neuroplasticity Group, Magdeburg, Germany
| | - Tuvshinjargal Budragchaa
- Leibniz Institute of Plant Biochemistry (IPB), Department of Bioorganic Chemistry, Halle (Saale), Germany
| | - Bernhard Westermann
- Leibniz Institute of Plant Biochemistry (IPB), Department of Bioorganic Chemistry, Halle (Saale), Germany
| | - Dushyant Mishra
- University of Würzburg, Biocenter Am Hubland, Department of Genetics and Neurobiology, Würzburg, Germany
| | - Claire Eschbach
- University of Würzburg, Biocenter Am Hubland, Department of Genetics and Neurobiology, Würzburg, Germany
| | | | - Annika Lingnau
- Free University Berlin, Institute of Neurobiology, Berlin, Germany
| | - Caroline Vahl
- Free University Berlin, Institute of Neurobiology, Berlin, Germany
| | - Marike Hilker
- Free University Berlin, Institute of Neurobiology, Berlin, Germany
| | - Randolf Menzel
- Free University Berlin, Institute of Neurobiology, Berlin, Germany
| | - Thilo Kähne
- Otto von Guericke University, Institute of Experimental Internal Medicine, Magdeburg, Germany
| | - Volkmar Leßmann
- Otto von Guericke University, Medical Faculty, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Otto von Guericke University, Magdeburg, Germany
| | - Alexander Dityatev
- Center for Behavioral Brain Sciences (CBBS), Otto von Guericke University, Magdeburg, Germany
- German Center for Neurodegenerative Diseases (DZNE), Molecular Neuroplasticity Group, Magdeburg, Germany
- Otto von Guericke University, Medical Faculty, Magdeburg, Germany
| | - Ludger Wessjohann
- Leibniz Institute of Plant Biochemistry (IPB), Department of Bioorganic Chemistry, Halle (Saale), Germany
| | - Bertram Gerber
- Leibniz Institute for Neurobiology, Department Genetics of Learning and Memory, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Otto von Guericke University, Magdeburg, Germany
- Otto von Guericke University, Institute of Biology, Magdeburg, Germany
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38
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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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39
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Harris KP, Littleton JT, Stewart BA. Postsynaptic Syntaxin 4 negatively regulates the efficiency of neurotransmitter release. J Neurogenet 2018; 32:221-229. [PMID: 30175640 PMCID: PMC6317344 DOI: 10.1080/01677063.2018.1501372] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 07/13/2018] [Indexed: 12/12/2022]
Abstract
Signaling from the postsynaptic compartment regulates multiple aspects of synaptic development and function. Syntaxin 4 (Syx4) is a plasma membrane t-SNARE that promotes the growth and plasticity of Drosophila neuromuscular junctions (NMJs) by regulating the localization of key synaptic proteins in the postsynaptic compartment. Here, we describe electrophysiological analyses and report that loss of Syx4 leads to enhanced neurotransmitter release, despite a decrease in the number of active zones. We describe a requirement for postsynaptic Syx4 in regulating several presynaptic parameters, including Ca2+ cooperativity and the abundance of the presynaptic calcium channel Cacophony (Cac) at active zones. These findings indicate Syx4 negatively regulates presynaptic neurotransmitter release through a retrograde signaling mechanism from the postsynaptic compartment.
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Affiliation(s)
- Kathryn P Harris
- a Department of Biology , University of Toronto Mississauga , Mississauga , ON, Canada
- b Department of Cell and Systems Biology , University of Toronto , Toronto , ON, Canada
| | - J Troy Littleton
- c The Picower Institute for Learning and Memory , Massachusetts Institute of Technology , Cambridge , MA , USA
- d Department of Biology , Massachusetts Institute of Technology , Cambridge , MA , USA
- e Department of Brain and Cognitive Sciences , Massachusetts Institute of Technology , Cambridge , MA , USA
| | - Bryan A Stewart
- a Department of Biology , University of Toronto Mississauga , Mississauga , ON, Canada
- b Department of Cell and Systems Biology , University of Toronto , Toronto , ON, Canada
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40
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Böhme MA, Grasskamp AT, Walter AM. Regulation of synaptic release-site Ca 2+ channel coupling as a mechanism to control release probability and short-term plasticity. FEBS Lett 2018; 592:3516-3531. [PMID: 29993122 DOI: 10.1002/1873-3468.13188] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 06/26/2018] [Accepted: 07/06/2018] [Indexed: 12/31/2022]
Abstract
Synaptic transmission relies on the rapid fusion of neurotransmitter-containing synaptic vesicles (SVs), which happens in response to action potential (AP)-induced Ca2+ influx at active zones (AZs). A highly conserved molecular machinery cooperates at SV-release sites to mediate SV plasma membrane attachment and maturation, Ca2+ sensing, and membrane fusion. Despite this high degree of conservation, synapses - even within the same organism, organ or neuron - are highly diverse regarding the probability of APs to trigger SV fusion. Additionally, repetitive activation can lead to either strengthening or weakening of transmission. In this review, we discuss mechanisms controlling release probability and this short-term plasticity. We argue that an important layer of control is exerted by evolutionarily conserved AZ scaffolding proteins, which determine the coupling distance between SV fusion sites and voltage-gated Ca2+ channels (VGCC) and, thereby, shape synapse-specific input/output behaviors. We propose that AZ-scaffold modifications may occur to adapt the coupling distance during synapse maturation and plastic regulation of synapse strength.
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Affiliation(s)
- Mathias A Böhme
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | | | - Alexander M Walter
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
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41
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Akbergenova Y, Cunningham KL, Zhang YV, Weiss S, Littleton JT. Characterization of developmental and molecular factors underlying release heterogeneity at Drosophila synapses. eLife 2018; 7:38268. [PMID: 29989549 PMCID: PMC6075867 DOI: 10.7554/elife.38268] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 06/30/2018] [Indexed: 12/14/2022] Open
Abstract
Neurons communicate through neurotransmitter release at specialized synaptic regions known as active zones (AZs). Using biosensors to visualize single synaptic vesicle fusion events at Drosophila neuromuscular junctions, we analyzed the developmental and molecular determinants of release probability (Pr) for a defined connection with ~300 AZs. Pr was heterogeneous but represented a stable feature of each AZ. Pr remained stable during high frequency stimulation and retained heterogeneity in mutants lacking the Ca2+ sensor Synaptotagmin 1. Pr correlated with both presynaptic Ca2+ channel abundance and Ca2+ influx at individual release sites. Pr heterogeneity also correlated with glutamate receptor abundance, with high Pr connections developing receptor subtype segregation. Intravital imaging throughout development revealed that AZs acquire high Pr during a multi-day maturation period, with Pr heterogeneity largely reflecting AZ age. The rate of synapse maturation was activity-dependent, as both increases and decreases in neuronal activity modulated glutamate receptor field size and segregation. To send a message to its neighbor, a neuron releases chemicals called neurotransmitters into the gap – or synapse – between them. The neurotransmitter molecules bind to proteins on the receiver neuron called receptors. But what causes the sender neuron to release neurotransmitter in the first place? The process starts when an electrical impulse called an action potential arrives at the sender cell. Its arrival causes channels in the membrane of the sender neuron to open, so that calcium ions flood into the cell. The calcium ions interact with packages of neurotransmitter molecules, known as synaptic vesicles. This causes some of the vesicles to empty their contents into the synapse. But this process is not particularly reliable. Only a small fraction of action potentials cause vesicles to fuse with the synaptic membrane. How likely this is to occur varies greatly between neurons, and even between synapses formed by the same neuron. Synapses that are likely to release neurotransmitter are said to be strong. They are good at passing messages from the sender neuron to the receiver. Synapses with a low probability of release are said to be weak. But what exactly differs between strong and weak synapses? Akbergenova et al. studied synapses between motor neurons and muscle cells in the fruit fly Drosophila. Each motor neuron forms several hundred synapses. Some of these synapses are 50 times more likely to release neurotransmitter than others. Using calcium imaging and genetics, Akbergenova et al. showed that sender cells at strong synapses have more calcium channels than sender cells at weak synapses. The subtypes and arrangement of receptor proteins also differ between the receiver neurons of strong versus weak synapses. Finally, studies in larvae revealed that newly formed synapses all start out weak and then gradually become stronger. How fast this strengthening occurs depends on how active the neuron at the synapse is. This study has shown, in unprecedented detail, key molecular factors that make some fruit fly synapses more likely to release neurotransmitter than others. Many proteins at synapses of mammals resemble those at fruit fly synapses. This means that similar factors may also explain differences in synaptic strength in the mammalian brain. Changes in the strength of synapses underlie the ability to learn. Furthermore, many neurological and psychiatric disorders result from disruption of synapses. Understanding the molecular basis of synapses will thus provide clues to the origins of certain brain diseases.
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Affiliation(s)
- Yulia Akbergenova
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, United States.,Department of Biology, Massachusetts Institute of Technology, Cambridge, United States.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Karen L Cunningham
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, United States.,Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Yao V Zhang
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, United States.,Department of Biology, Massachusetts Institute of Technology, Cambridge, United States.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Shirley Weiss
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, United States.,Department of Biology, Massachusetts Institute of Technology, Cambridge, United States.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - J Troy Littleton
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, United States.,Department of Biology, Massachusetts Institute of Technology, Cambridge, United States.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
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42
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Heine J, Wurm CA, Keller-Findeisen J, Schönle A, Harke B, Reuss M, Winter FR, Donnert G. Three dimensional live-cell STED microscopy at increased depth using a water immersion objective. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:053701. [PMID: 29864829 DOI: 10.1063/1.5020249] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Modern fluorescence superresolution microscopes are capable of imaging living cells on the nanometer scale. One of those techniques is stimulated emission depletion (STED) which increases the microscope's resolution many times in the lateral and the axial directions. To achieve these high resolutions not only close to the coverslip but also at greater depths, the choice of objective becomes crucial. Oil immersion objectives have frequently been used for STED imaging since their high numerical aperture (NA) leads to high spatial resolutions. But during live-cell imaging, especially at great penetration depths, these objectives have a distinct disadvantage. The refractive index mismatch between the immersion oil and the usually aqueous embedding media of living specimens results in unwanted spherical aberrations. These aberrations distort the point spread functions (PSFs). Notably, during z- and 3D-STED imaging, the resolution increase along the optical axis is majorly hampered if at all possible. To overcome this limitation, we here use a water immersion objective in combination with a spatial light modulator for z-STED measurements of living samples at great depths. This compact design allows for switching between objectives without having to adapt the STED beam path and enables on the fly alterations of the STED PSF to correct for aberrations. Furthermore, we derive the influence of the NA on the axial STED resolution theoretically and experimentally. We show under live-cell imaging conditions that a water immersion objective leads to far superior results than an oil immersion objective at penetration depths of 5-180 μm.
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Affiliation(s)
- Jörn Heine
- Abberior Instruments GmbH, Hans-Adolf-Krebs-Weg 1, 37077 Göttingen, Germany
| | - Christian A Wurm
- Abberior Instruments GmbH, Hans-Adolf-Krebs-Weg 1, 37077 Göttingen, Germany
| | - Jan Keller-Findeisen
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Andreas Schönle
- Abberior Instruments GmbH, Hans-Adolf-Krebs-Weg 1, 37077 Göttingen, Germany
| | - Benjamin Harke
- Abberior Instruments GmbH, Hans-Adolf-Krebs-Weg 1, 37077 Göttingen, Germany
| | - Matthias Reuss
- Abberior Instruments GmbH, Hans-Adolf-Krebs-Weg 1, 37077 Göttingen, Germany
| | - Franziska R Winter
- Abberior Instruments GmbH, Hans-Adolf-Krebs-Weg 1, 37077 Göttingen, Germany
| | - Gerald Donnert
- Abberior Instruments GmbH, Hans-Adolf-Krebs-Weg 1, 37077 Göttingen, Germany
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43
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Jiang N, Kim HJ, Chozinski TJ, Azpurua JE, Eaton BA, Vaughan JC, Parrish JZ. Superresolution imaging of Drosophila tissues using expansion microscopy. Mol Biol Cell 2018; 29:1413-1421. [PMID: 29688792 PMCID: PMC6014096 DOI: 10.1091/mbc.e17-10-0583] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The limited resolving power of conventional diffraction-limited microscopy hinders analysis of small, densely packed structural elements in cells. Expansion microscopy (ExM) provides an elegant solution to this problem, allowing for increased resolution with standard microscopes via physical expansion of the specimen in a swellable polymer hydrogel. Here, we apply, validate, and optimize ExM protocols that enable the study of Drosophila embryos, larval brains, and larval and adult body walls. We achieve a lateral resolution of ∼70 nm in Drosophila tissues using a standard confocal microscope, and we use ExM to analyze fine intracellular structures and intercellular interactions. First, we find that ExM reveals features of presynaptic active zone (AZ) structure that are observable with other superresolution imaging techniques but not with standard confocal microscopy. We further show that synapses known to exhibit age-dependent changes in activity also exhibit age-dependent changes in AZ structure. Finally, we use the significantly improved axial resolution of ExM to show that dendrites of somatosensory neurons are inserted into epithelial cells at a higher frequency than previously reported in confocal microscopy studies. Altogether, our study provides a foundation for the application of ExM to Drosophila tissues and underscores the importance of tissue-specific optimization of ExM procedures.
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Affiliation(s)
- Nan Jiang
- Department of Biology, University of Washington, Seattle, WA 98195
| | - Hyeon-Jin Kim
- Department of Chemistry, University of Washington, Seattle, WA 98195
| | - Tyler J Chozinski
- Department of Chemistry, University of Washington, Seattle, WA 98195
| | - Jorge E Azpurua
- Department of Physiology, University of Texas Health Sciences Center, San Antonio, TX 78229
| | - Benjamin A Eaton
- Department of Physiology, University of Texas Health Sciences Center, San Antonio, TX 78229
| | - Joshua C Vaughan
- Department of Chemistry, University of Washington, Seattle, WA 98195
| | - Jay Z Parrish
- Department of Biology, University of Washington, Seattle, WA 98195
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44
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Li X, Goel P, Chen C, Angajala V, Chen X, Dickman DK. Synapse-specific and compartmentalized expression of presynaptic homeostatic potentiation. eLife 2018; 7:34338. [PMID: 29620520 PMCID: PMC5927770 DOI: 10.7554/elife.34338] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 04/04/2018] [Indexed: 01/23/2023] Open
Abstract
Postsynaptic compartments can be specifically modulated during various forms of synaptic plasticity, but it is unclear whether this precision is shared at presynaptic terminals. Presynaptic homeostatic plasticity (PHP) stabilizes neurotransmission at the Drosophila neuromuscular junction, where a retrograde enhancement of presynaptic neurotransmitter release compensates for diminished postsynaptic receptor functionality. To test the specificity of PHP induction and expression, we have developed a genetic manipulation to reduce postsynaptic receptor expression at one of the two muscles innervated by a single motor neuron. We find that PHP can be induced and expressed at a subset of synapses, over both acute and chronic time scales, without influencing transmission at adjacent release sites. Further, homeostatic modulations to CaMKII, vesicle pools, and functional release sites are compartmentalized and do not spread to neighboring pre- or post-synaptic structures. Thus, both PHP induction and expression mechanisms are locally transmitted and restricted to specific synaptic compartments. Everything we think and do is the result of communication between neurons. This communication takes place at junctions called synapses. When two nerve cells or neurons communicate at a synapse, the output terminal of the first cell releases a chemical called a neurotransmitter. This binds to receiver proteins, or receptors, on the second cell. When this communication is interrupted, synapses can adapt to maintain a stable dialogue between them. This can occur in two ways. Either the first neuron starts to release more neurotransmitter from its output terminal, or the second neuron produces extra receptors with which to detect the neurotransmitter. But how specific are these changes? The brain contains far more synapses than neurons because each neuron can form synapses with many other cells. Can a neuron adjust how much of the neurotransmitter it releases at some of its synapses while leaving the others unchanged? Li et al. have now addressed this question by studying a special type of synapse that forms between neurons and muscles, known as a neuromuscular junction. At one particular neuromuscular junction in fruit flies, a single neuron splits into two output terminals, each of which forms a synapse with a different muscle. Li et al. show that when the number of neurotransmitter receptors in one of the muscles is artificially reduced, the associated output terminal compensates by increasing its neurotransmitter release. By contrast, the other output terminal remains unaffected. This suggests that a neuron can induce remarkably specific changes in a subset of its synapses. This discovery paves the way towards identifying the smallest possible unit of change that can occur in the neurons’ ability to communicate. This unit may in turn be the smallest change that can support learning. Such knowledge will help us understand how the nervous system processes and stabilizes information transfer, both in health and after injury or disease.
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Affiliation(s)
- Xiling Li
- Department of Neurobiology, University of Southern California, Los Angeles, United States.,Neuroscience Graduate Program, University of Southern California, California, United States
| | - Pragya Goel
- Department of Neurobiology, University of Southern California, Los Angeles, United States.,Graduate Program in Molecular and Computational Biology, University of Southern California, California, United States
| | - Catherine Chen
- Department of Neurobiology, University of Southern California, Los Angeles, United States
| | | | - Xun Chen
- Neuroscience Graduate Program, University of Southern California, California, United States
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45
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Migh E, Götz T, Földi I, Szikora S, Gombos R, Darula Z, Medzihradszky KF, Maléth J, Hegyi P, Sigrist S, Mihály J. Microtubule organization in presynaptic boutons relies on the formin DAAM. Development 2018; 145:dev.158519. [PMID: 29487108 DOI: 10.1242/dev.158519] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 02/14/2018] [Indexed: 02/02/2023]
Abstract
Regulation of the cytoskeleton is fundamental to the development and function of synaptic terminals, such as neuromuscular junctions. Despite the identification of numerous proteins that regulate synaptic actin and microtubule dynamics, the mechanisms of cytoskeletal control during terminal arbor formation have remained largely elusive. Here, we show that DAAM, a member of the formin family of cytoskeleton organizing factors, is an important presynaptic regulator of neuromuscular junction development in Drosophila We demonstrate that the actin filament assembly activity of DAAM plays a negligible role in terminal formation; rather, DAAM is necessary for synaptic microtubule organization. Genetic interaction studies consistently link DAAM with the Wg/Ank2/Futsch module of microtubule regulation and bouton formation. Finally, we provide evidence that DAAM is tightly associated with the synaptic active zone scaffold, and electrophysiological data point to a role in the modulation of synaptic vesicle release. Based on these results, we propose that DAAM is an important cytoskeletal effector element of the Wg/Ank2 pathway involved in the determination of basic synaptic structures, and, additionally, that DAAM may couple the active zone scaffold to the presynaptic cytoskeleton.
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Affiliation(s)
- Ede Migh
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, MTA-SZBK NAP B Axon Growth and Regeneration Group, Temesvári krt. 62, Szeged H-6726, Hungary
| | - Torsten Götz
- Institut für Biologie/Genetik and NeuroCure, Freie Universitat Berlin, Takustrasse 6, D-14195 Berlin, Germany
| | - István Földi
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, MTA-SZBK NAP B Axon Growth and Regeneration Group, Temesvári krt. 62, Szeged H-6726, Hungary
| | - Szilárd Szikora
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, MTA-SZBK NAP B Axon Growth and Regeneration Group, Temesvári krt. 62, Szeged H-6726, Hungary
| | - Rita Gombos
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, MTA-SZBK NAP B Axon Growth and Regeneration Group, Temesvári krt. 62, Szeged H-6726, Hungary
| | - Zsuzsanna Darula
- Laboratory of Proteomics Research, Biological Research Centre, Hungarian Academy of Sciences, Szeged H-6726, Hungary
| | - Katalin F Medzihradszky
- Laboratory of Proteomics Research, Biological Research Centre, Hungarian Academy of Sciences, Szeged H-6726, Hungary
| | - József Maléth
- MTA-SZTE Translational Gastroenterology Research Group, Szeged H-6725, Hungary
| | - Péter Hegyi
- MTA-SZTE Translational Gastroenterology Research Group, Szeged H-6725, Hungary.,Institute for Translational Medicine, University of Pecs, Pécs H-7624, Hungary
| | - Stephan Sigrist
- Institut für Biologie/Genetik and NeuroCure, Freie Universitat Berlin, Takustrasse 6, D-14195 Berlin, Germany
| | - József Mihály
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, MTA-SZBK NAP B Axon Growth and Regeneration Group, Temesvári krt. 62, Szeged H-6726, Hungary
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46
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Ehmann N, Owald D, Kittel RJ. Drosophila active zones: From molecules to behaviour. Neurosci Res 2018; 127:14-24. [DOI: 10.1016/j.neures.2017.11.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Revised: 11/30/2017] [Accepted: 11/30/2017] [Indexed: 11/15/2022]
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47
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Hamada S, Ohtsuka T. CAST: Its molecular structure and phosphorylation-dependent regulation of presynaptic plasticity. Neurosci Res 2018; 127:25-32. [DOI: 10.1016/j.neures.2017.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 12/05/2017] [Accepted: 12/06/2017] [Indexed: 11/16/2022]
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48
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Walter AM, Böhme MA, Sigrist SJ. Vesicle release site organization at synaptic active zones. Neurosci Res 2017; 127:3-13. [PMID: 29275162 DOI: 10.1016/j.neures.2017.12.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 12/04/2017] [Accepted: 12/06/2017] [Indexed: 11/30/2022]
Abstract
Information transfer between nerve cells (neurons) forms the basis of behavior, emotion, and survival. Signal transduction from one neuron to another occurs at synapses, and relies on both electrical and chemical signal propagation. At chemical synapses, incoming electrical action potentials trigger the release of chemical neurotransmitters that are sensed by the connected cell and here reconverted to an electrical signal. The presynaptic conversion of an electrical to a chemical signal is an energy demanding, highly regulated process that relies on a complex, evolutionarily conserved molecular machinery. Here, we review the biophysical characteristics of this process, the current knowledge of the molecules operating in this reaction and genetic specializations that may have evolved to shape inter-neuronal signaling.
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Affiliation(s)
- Alexander M Walter
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, Berlin 13125, Germany.
| | - Mathias A Böhme
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, Berlin 13125, Germany
| | - Stephan J Sigrist
- Freie Universität Berlin, Institute for Biology/Genetics, Takustraße 6, 14195 Berlin, Germany; NeuroCure, Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany.
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49
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Xuan Z, Manning L, Nelson J, Richmond JE, Colón-Ramos DA, Shen K, Kurshan PT. Clarinet (CLA-1), a novel active zone protein required for synaptic vesicle clustering and release. eLife 2017; 6:29276. [PMID: 29160205 PMCID: PMC5728718 DOI: 10.7554/elife.29276] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Accepted: 11/20/2017] [Indexed: 01/03/2023] Open
Abstract
Active zone proteins cluster synaptic vesicles at presynaptic terminals and coordinate their release. In forward genetic screens, we isolated a novel Caenorhabditis elegans active zone gene, clarinet (cla-1). cla-1 mutants exhibit defects in synaptic vesicle clustering, active zone structure and synapse number. As a result, they have reduced spontaneous vesicle release and increased synaptic depression. cla-1 mutants show defects in vesicle distribution near the presynaptic dense projection, with fewer undocked vesicles contacting the dense projection and more docked vesicles at the plasma membrane. cla-1 encodes three isoforms containing common C-terminal PDZ and C2 domains with homology to vertebrate active zone proteins Piccolo and RIM. The C-termini of all isoforms localize to the active zone. Specific loss of the ~9000 amino acid long isoform results in vesicle clustering defects and increased synaptic depression. Our data indicate that specific isoforms of clarinet serve distinct functions, regulating synapse development, vesicle clustering and release.
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Affiliation(s)
- Zhao Xuan
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States.,Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Yale University School of Medicine, New Haven, United States
| | - Laura Manning
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Jessica Nelson
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States.,Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Yale University School of Medicine, New Haven, United States
| | - Janet E Richmond
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Daniel A Colón-Ramos
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States.,Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Yale University School of Medicine, New Haven, United States.,Instituto de Neurobiología, Recinto de Ciencias Médicas, Universidad de Puerto Rico, San Juan, Puerto Rico
| | - Kang Shen
- Department of Biology, Stanford University, Stanford, United States.,Howard Hughes Medical Institute
| | - Peri T Kurshan
- Department of Biology, Stanford University, Stanford, United States
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50
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Wu CH, Giampetruzzi A, Tran H, Fallini C, Gao FB, Landers JE. A Drosophila model of ALS reveals a partial loss of function of causative human PFN1 mutants. Hum Mol Genet 2017; 26:2146-2155. [PMID: 28379367 DOI: 10.1093/hmg/ddx112] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 03/16/2017] [Indexed: 01/04/2023] Open
Abstract
Mutations in the profilin 1 (PFN1) gene are causative for familial amyotrophic lateral sclerosis (fALS). However, it is still not fully understood how these mutations lead to neurodegeneration. To address this question, we generated a novel Drosophila model expressing human wild-type and ALS-causative PFN1 mutants. We show that at larval neuromuscular junctions (NMJ), motor neuron expression of wild-type human PFN1 increases the number of ghost boutons, active zone density, F-actin content, and the formation of filopodia. In contrast, the expression of ALS-causative human PFN1 mutants causes a less pronounced phenotype, suggesting a loss of function of these mutants in promoting NMJ remodeling. Importantly, expression of human PFN1 in motor neurons results in progressive locomotion defects and shorter lifespan in adult flies, while ALS-causative PFN1 mutants display a less toxic effect. In summary, our study provides evidence that PFN1 is important in regulating NMJ morphology and influences survival and locomotion in Drosophila. Furthermore, our results suggest ALS-causative human PFN1 mutants display a partial loss of function relative to wild-type hPFN1 that may contribute to human disease pathogenesis.
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Affiliation(s)
- Chi-Hong Wu
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Anthony Giampetruzzi
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Helene Tran
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Claudia Fallini
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Fen-Biao Gao
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - John E Landers
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01605, USA
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