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Gao J, Zhang S, Deng P, Wu Z, Lemaitre B, Zhai Z, Guo Z. Dietary L-Glu sensing by enteroendocrine cells adjusts food intake via modulating gut PYY/NPF secretion. Nat Commun 2024; 15:3514. [PMID: 38664401 PMCID: PMC11045819 DOI: 10.1038/s41467-024-47465-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 03/28/2024] [Indexed: 04/28/2024] Open
Abstract
Amino acid availability is monitored by animals to adapt to their nutritional environment. Beyond gustatory receptors and systemic amino acid sensors, enteroendocrine cells (EECs) are believed to directly percept dietary amino acids and secrete regulatory peptides. However, the cellular machinery underlying amino acid-sensing by EECs and how EEC-derived hormones modulate feeding behavior remain elusive. Here, by developing tools to specifically manipulate EECs, we find that Drosophila neuropeptide F (NPF) from mated female EECs inhibits feeding, similar to human PYY. Mechanistically, dietary L-Glutamate acts through the metabotropic glutamate receptor mGluR to decelerate calcium oscillations in EECs, thereby causing reduced NPF secretion via dense-core vesicles. Furthermore, two dopaminergic enteric neurons expressing NPFR perceive EEC-derived NPF and relay an anorexigenic signal to the brain. Thus, our findings provide mechanistic insights into how EECs assess food quality and identify a conserved mode of action that explains how gut NPF/PYY modulates food intake.
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Affiliation(s)
- Junjun Gao
- Department of Medical Genetics, School of Basic Medicine, Institute for Brain Research, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Song Zhang
- Department of Medical Genetics, School of Basic Medicine, Institute for Brain Research, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Pan Deng
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, PR China
- Department of Mechanical Engineering, University of British Columbia, Vancouver, British Columbia, Canada
| | - Zhigang Wu
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, PR China
| | - Bruno Lemaitre
- Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Zongzhao Zhai
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, Hunan, PR China.
| | - Zheng Guo
- Department of Medical Genetics, School of Basic Medicine, Institute for Brain Research, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
- Cell Architecture Research Center, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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2
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Kowalski A, Betzer C, Larsen ST, Gregersen E, Newcombe EA, Bermejo MC, Bendtsen VW, Diemer J, Ernstsen CV, Jain S, Bou AE, Langkilde AE, Nejsum LN, Klipp E, Edwards R, Kragelund BB, Jensen PH, Nissen P. Monomeric α-synuclein activates the plasma membrane calcium pump. EMBO J 2023; 42:e111122. [PMID: 37916890 PMCID: PMC10690453 DOI: 10.15252/embj.2022111122] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 09/19/2023] [Accepted: 10/11/2023] [Indexed: 11/03/2023] Open
Abstract
Alpha-synuclein (aSN) is a membrane-associated and intrinsically disordered protein, well known for pathological aggregation in neurodegeneration. However, the physiological function of aSN is disputed. Pull-down experiments have pointed to plasma membrane Ca2+ -ATPase (PMCA) as a potential interaction partner. From proximity ligation assays, we find that aSN and PMCA colocalize at neuronal synapses, and we show that calcium expulsion is activated by aSN and PMCA. We further show that soluble, monomeric aSN activates PMCA at par with calmodulin, but independent of the autoinhibitory domain of PMCA, and highly dependent on acidic phospholipids and membrane-anchoring properties of aSN. On PMCA, the key site is mapped to the acidic lipid-binding site, located within a disordered PMCA-specific loop connecting the cytosolic A domain and transmembrane segment 3. Our studies point toward a novel physiological role of monomeric aSN as a stimulator of calcium clearance in neurons through activation of PMCA.
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Affiliation(s)
- Antoni Kowalski
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
- REPIN and Structural Biology and NMR Laboratory, Department of BiologyUniversity of CopenhagenCopenhagenDenmark
- Department of Molecular NeurochemistryMedical University of LodzLodzPoland
- Present address:
ImmunAware ApSHørsholmDenmark
| | - Cristine Betzer
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
- Department of BiomedicineAarhus UniversityAarhusDenmark
- Present address:
Region Midtjylland, Regionshospitalet GødstrupHerningDenmark
| | - Sigrid Thirup Larsen
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
| | - Emil Gregersen
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
- Department of BiomedicineAarhus UniversityAarhusDenmark
- Present address:
Department of Clinical MedicineAarhus UniversityAarhus NDenmark
| | - Estella A Newcombe
- REPIN and Structural Biology and NMR Laboratory, Department of BiologyUniversity of CopenhagenCopenhagenDenmark
| | - Montaña Caballero Bermejo
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
- Department Biochemistry and Molecular Biology and Genetics, IBMPUniversity of ExtremaduraBadajozSpain
| | - Viktor Wisniewski Bendtsen
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
| | - Jorin Diemer
- Theoretical BiophysicsHumboldt‐Universität zu BerlinBerlinGermany
| | | | - Shweta Jain
- Departments of Neurology and PhysiologyUniversity of California San FranciscoSan FranciscoCAUSA
| | - Alicia Espiña Bou
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
| | | | - Lene N Nejsum
- Department of Clinical MedicineAarhus UniversityAarhus NDenmark
| | - Edda Klipp
- Theoretical BiophysicsHumboldt‐Universität zu BerlinBerlinGermany
| | - Robert Edwards
- Departments of Neurology and PhysiologyUniversity of California San FranciscoSan FranciscoCAUSA
| | - Birthe B Kragelund
- REPIN and Structural Biology and NMR Laboratory, Department of BiologyUniversity of CopenhagenCopenhagenDenmark
| | - Poul Henning Jensen
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
- Department of BiomedicineAarhus UniversityAarhusDenmark
| | - Poul Nissen
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
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3
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Mueller BD, Merrill SA, Watanabe S, Liu P, Niu L, Singh A, Maldonado-Catala P, Cherry A, Rich MS, Silva M, Maricq AV, Wang ZW, Jorgensen EM. CaV1 and CaV2 calcium channels mediate the release of distinct pools of synaptic vesicles. eLife 2023; 12:e81407. [PMID: 36820519 PMCID: PMC10023163 DOI: 10.7554/elife.81407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 02/22/2023] [Indexed: 02/24/2023] Open
Abstract
Activation of voltage-gated calcium channels at presynaptic terminals leads to local increases in calcium and the fusion of synaptic vesicles containing neurotransmitter. Presynaptic output is a function of the density of calcium channels, the dynamic properties of the channel, the distance to docked vesicles, and the release probability at the docking site. We demonstrate that at Caenorhabditis elegans neuromuscular junctions two different classes of voltage-gated calcium channels, CaV2 and CaV1, mediate the release of distinct pools of synaptic vesicles. CaV2 channels are concentrated in densely packed clusters ~250 nm in diameter with the active zone proteins Neurexin, α-Liprin, SYDE, ELKS/CAST, RIM-BP, α-Catulin, and MAGI1. CaV2 channels are colocalized with the priming protein UNC-13L and mediate the fusion of vesicles docked within 33 nm of the dense projection. CaV2 activity is amplified by ryanodine receptor release of calcium from internal stores, triggering fusion up to 165 nm from the dense projection. By contrast, CaV1 channels are dispersed in the synaptic varicosity, and are colocalized with UNC-13S. CaV1 and ryanodine receptors are separated by just 40 nm, and vesicle fusion mediated by CaV1 is completely dependent on the ryanodine receptor. Distinct synaptic vesicle pools, released by different calcium channels, could be used to tune the speed, voltage-dependence, and quantal content of neurotransmitter release.
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Affiliation(s)
- Brian D Mueller
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Sean A Merrill
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Shigeki Watanabe
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Ping Liu
- Department of Neuroscience, University of Connecticut Medical SchoolFarmingtonUnited States
| | - Longgang Niu
- Department of Neuroscience, University of Connecticut Medical SchoolFarmingtonUnited States
| | - Anish Singh
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | | | - Alex Cherry
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Matthew S Rich
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Malan Silva
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | | | - Zhao-Wen Wang
- Department of Neuroscience, University of Connecticut Medical SchoolFarmingtonUnited States
| | - Erik M Jorgensen
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
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Ghelani T, Escher M, Thomas U, Esch K, Lützkendorf J, Depner H, Maglione M, Parutto P, Gratz S, Matkovic-Rachid T, Ryglewski S, Walter AM, Holcman D, O‘Connor Giles K, Heine M, Sigrist SJ. Interactive nanocluster compaction of the ELKS scaffold and Cacophony Ca 2+ channels drives sustained active zone potentiation. SCIENCE ADVANCES 2023; 9:eade7804. [PMID: 36800417 PMCID: PMC9937578 DOI: 10.1126/sciadv.ade7804] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 01/17/2023] [Indexed: 06/01/2023]
Abstract
At presynaptic active zones (AZs), conserved scaffold protein architectures control synaptic vesicle (SV) release by defining the nanoscale distribution and density of voltage-gated Ca2+ channels (VGCCs). While AZs can potentiate SV release in the minutes range, we lack an understanding of how AZ scaffold components and VGCCs engage into potentiation. We here establish dynamic, intravital single-molecule imaging of endogenously tagged proteins at Drosophila AZs undergoing presynaptic homeostatic potentiation. During potentiation, the numbers of α1 VGCC subunit Cacophony (Cac) increased per AZ, while their mobility decreased and nanoscale distribution compacted. These dynamic Cac changes depended on the interaction between Cac channel's intracellular carboxyl terminus and the membrane-close amino-terminal region of the ELKS-family protein Bruchpilot, whose distribution compacted drastically. The Cac-ELKS/Bruchpilot interaction was also needed for sustained AZ potentiation. Our single-molecule analysis illustrates how the AZ scaffold couples to VGCC nanoscale distribution and dynamics to establish a state of sustained potentiation.
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Affiliation(s)
- Tina Ghelani
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
- Molecular and Theoretical Neuroscience Leibniz-Forschungs Institut für Molekulare Pharmakologie (FMP) im CharitéCrossOver (CCO) Charité–University Medicine Berlin Charité Campus Mitte, Charité Platz, 110117 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
| | - Marc Escher
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Ulrich Thomas
- Department of Cellular Neurobiology, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany
| | - Klara Esch
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Janine Lützkendorf
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Harald Depner
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Marta Maglione
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
- Institute for Chemistry and Biochemistry, SupraFAB, Freie Universität Berlin, Altensteinstr. 23a, 14195 Berlin, Germany
| | - Pierre Parutto
- Group of Applied Mathematics and Computational Biology, IBENS, Ecole Normale Superieure, Paris, France
- Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Cambridge CB2 0AH, UK
- Churchill College, University of Cambridge, Cambridge CB3 0DS, UK
| | - Scott Gratz
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Tanja Matkovic-Rachid
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
| | - Stefanie Ryglewski
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Alexander M. Walter
- Molecular and Theoretical Neuroscience Leibniz-Forschungs Institut für Molekulare Pharmakologie (FMP) im CharitéCrossOver (CCO) Charité–University Medicine Berlin Charité Campus Mitte, Charité Platz, 110117 Berlin, Germany
- Department of Neuroscience, University of Copenhagen, Copenhagen 2200, Denmark
| | - David Holcman
- Group of Applied Mathematics and Computational Biology, IBENS, Ecole Normale Superieure, Paris, France
- Churchill College, University of Cambridge, Cambridge CB3 0DS, UK
| | - Kate O‘Connor Giles
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
- Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA
| | - Martin Heine
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
- Research Group Molecular Physiology, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany
| | - Stephan J. Sigrist
- Institute for Biology and Genetics, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
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5
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Zi Y, Barker JR, MacIsaac HJ, Zhang R, Gras R, Chiang YC, Zhou Y, Lu F, Cai W, Sun C, Chang X. Identification of neurotoxic compounds in cyanobacteria exudate mixtures. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 857:159257. [PMID: 36208737 DOI: 10.1016/j.scitotenv.2022.159257] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 10/01/2022] [Accepted: 10/01/2022] [Indexed: 06/16/2023]
Abstract
Release of toxic cyanobacterial secondary metabolites threatens biosecurity, foodwebs and public health. Microcystis aeruginosa (Ma), the dominant species in global freshwater cyanobacterial blooms, produces exudates (MaE) that cause adverse outcomes including nerve damage. Previously, we identified > 300 chemicals in MaE. It is critical to investigate neurotoxicity mechanisms of active substances among this suite of Ma compounds. Here, we screened 103 neurotoxicity assays from the ToxCast database to reveal targets of action of MaE using machine learning. We then built a potential Adverse Outcome Pathway (AOP) to identify neurotoxicity mechanisms of MaE as well as key targets. Finally, we selected potential neurotoxins matched with those targets using molecular docking. We found 38 targets that were inhibited and eight targets that were activated, collectively mainly related to neurotransmission (i.e. cholinergic, dopaminergic and serotonergic neurotransmitter systems). The potential AOP of MaE neurotoxicity could be caused by blocking calcium voltage-gated channel (CACNA1A), because of antagonizing neurotransmitter receptors, or because of inhibiting solute carrier transporters. We identified nine neurotoxic MaE compounds with high affinity to those targets, including LysoPC(16:0), 2-acetyl-1-alkyl-sn-glycero-3-phosphocholine, egonol glucoside, polyoxyethylene (600) monoricinoleate, and phytosphingosine. Our study enhances understanding of neurotoxicity mechanisms and identifies neurotoxins in cyanobacterial bloom exudates, which may help identify priority compounds for cyanobacteria management.
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Affiliation(s)
- Yuanyan Zi
- School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, PR China; Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON N9 B 3P4, Canada
| | - Justin R Barker
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON N9 B 3P4, Canada
| | - Hugh J MacIsaac
- School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, PR China; Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON N9 B 3P4, Canada
| | - Ruihan Zhang
- Key Laboratory of Medicinal Chemistry for Natural Resources, Ministry of Education and Yunnan Province, School of Chemical Science and Technology, Yunnan University, Kunming 650091, China
| | - Robin Gras
- School of Computer Science, University of Windsor, ON N9B 3P4, Canada
| | - Ying-Chih Chiang
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Science, The Chinese University of Hong Kong (Shenzhen), Shenzhen 518172, China
| | - Yuan Zhou
- School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, PR China
| | - Fangchi Lu
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Science, The Chinese University of Hong Kong (Shenzhen), Shenzhen 518172, China
| | - Wenwen Cai
- School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, PR China; Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON N9 B 3P4, Canada
| | - Chunxiao Sun
- School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, PR China; Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON N9 B 3P4, Canada
| | - Xuexiu Chang
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON N9 B 3P4, Canada; College of Agronomy and Life Sciences, Kunming University, Kunming 650214, China.
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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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7
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Armstrong NS, Frank CA. The calcineurin regulator Sarah enables distinct forms of homeostatic plasticity at the Drosophila neuromuscular junction. Front Synaptic Neurosci 2023; 14:1033743. [PMID: 36685082 PMCID: PMC9846150 DOI: 10.3389/fnsyn.2022.1033743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 12/05/2022] [Indexed: 01/05/2023] Open
Abstract
Introduction: The ability of synapses to maintain physiological levels of evoked neurotransmission is essential for neuronal stability. A variety of perturbations can disrupt neurotransmission, but synapses often compensate for disruptions and work to stabilize activity levels, using forms of homeostatic synaptic plasticity. Presynaptic homeostatic potentiation (PHP) is one such mechanism. PHP is expressed at the Drosophila melanogaster larval neuromuscular junction (NMJ) synapse, as well as other NMJs. In PHP, presynaptic neurotransmitter release increases to offset the effects of impairing muscle transmitter receptors. Prior Drosophila work has studied PHP using different ways to perturb muscle receptor function-either acutely (using pharmacology) or chronically (using genetics). Some of our prior data suggested that cytoplasmic calcium signaling was important for expression of PHP after genetic impairment of glutamate receptors. Here we followed up on that observation. Methods: We used a combination of transgenic Drosophila RNA interference and overexpression lines, along with NMJ electrophysiology, synapse imaging, and pharmacology to test if regulators of the calcium/calmodulin-dependent protein phosphatase calcineurin are necessary for the normal expression of PHP. Results: We found that either pre- or postsynaptic dysregulation of a Drosophila gene regulating calcineurin, sarah (sra), blocks PHP. Tissue-specific manipulations showed that either increases or decreases in sra expression are detrimental to PHP. Additionally, pharmacologically and genetically induced forms of expression of PHP are functionally separable depending entirely upon which sra genetic manipulation is used. Surprisingly, dual-tissue pre- and postsynaptic sra knockdown or overexpression can ameliorate PHP blocks revealed in single-tissue experiments. Pharmacological and genetic inhibition of calcineurin corroborated this latter finding. Discussion: Our results suggest tight calcineurin regulation is needed across multiple tissue types to stabilize peripheral synaptic outputs.
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Affiliation(s)
- Noah S. Armstrong
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA, United States,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA, United States
| | - C. Andrew Frank
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA, United States,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA, United States,Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, United States,*Correspondence: C. Andrew Frank
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Hendricks EL, Smith IR, Prates B, Barmaleki F, Liebl FLW. The CD63 homologs, Tsp42Ee and Tsp42Eg, restrict endocytosis and promote neurotransmission through differential regulation of synaptic vesicle pools. Front Cell Neurosci 2022; 16:957232. [PMID: 36072568 PMCID: PMC9441712 DOI: 10.3389/fncel.2022.957232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/04/2022] [Indexed: 11/30/2022] Open
Abstract
The Tetraspanin (Tsp), CD63, is a transmembrane component of late endosomes and facilitates vesicular trafficking through endosomal pathways. Despite being widely expressed in the human brain and localized to late endosomes, CD63's role in regulating endo- and exocytic cycling at the synapse has not been investigated. Synaptic vesicle pools are highly dynamic and disruptions in the mobilization and replenishment of these vesicle pools have adverse neuronal effects. We find that the CD63 homologs, Tsp42Ee and Tsp42Eg, are expressed at the Drosophila neuromuscular junction to regulate synaptic vesicle pools through both shared and unique mechanisms. Tsp42Ee and Tsp42Eg negatively regulate endocytosis and positively regulate neurotransmitter release. Both tsp mutants show impaired locomotion, reduced miniature endplate junctional current frequencies, and increased endocytosis. Expression of human CD63 in Drosophila neurons leads to impaired endocytosis suggesting the role of Tsps in endocytosis is conserved. We further show that Tsps influence the synaptic cytoskeleton and membrane composition by regulating Futsch loop formation and synaptic levels of SCAR and PI(4,5)P2. Finally, Tsp42Ee and Tsp42Eg influence the synaptic localization of several vesicle-associated proteins including Synapsin, Synaptotagmin, and Cysteine String Protein. Together, our results present a novel function for Tsps in the regulation of vesicle pools and provide insight into the molecular mechanisms of Tsp-related synaptic dysfunction.
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Affiliation(s)
| | | | | | | | - Faith L. W. Liebl
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, United States
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9
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Improved analysis method of neuromuscular junction in Drosophila larvae by transmission electron microscopy. Anat Sci Int 2021; 97:147-154. [PMID: 34661863 PMCID: PMC8732911 DOI: 10.1007/s12565-021-00635-6] [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: 08/06/2021] [Accepted: 10/04/2021] [Indexed: 11/04/2022]
Abstract
The Drosophila neuromuscular junction is an excellent model for neuroscience research. However, the distribution of neuromuscular junctions is very diffuse, and it is not easy to accurately locate during ultrathin sectioning, which seriously interferes with the ultrastructural analysis under electron microscopy that only has a small field of view. Here, we reported an efficient method for acquiring the ultrastructural picture of neuromuscular junctions in Drosophila larva under electron microscopy. The procedure was as follows: first, the larval sample of body wall muscle was placed between the metal mesh and was dehydrated with alcohol and infiltrated with epoxy resin to prevent the sample from curling or bending, after it was dissected and fixed into thin slices. Second, the sample was embedded in resin into a flat sheet to facilitate the positioning of the muscles. Third, carefully and gradually remove the excess resin and the cuticle of the larvae, cut off both ends of the special body segment, and trim the excess specific muscles according to the recommended ratio of trimming muscles, which would reduce the workload exponentially. At last, the trimmed sample were prepared into serial about 1000 ultrathin sections that was about total 80 microns thickness, and 30–40 sections were gathered into a grid to stain with lead citrate and uranyl acetate. This method could also be applied to the other small and thin samples such as the Drosophila embryo, ventral nerve cord and brain.
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