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O'Shaughnessy EC, Lam M, Ryken SE, Wiesner T, Lukasik K, Zuchero JB, Leterrier C, Adalsteinsson D, Gupton SL. pHusion - a robust and versatile toolset for automated detection and analysis of exocytosis. J Cell Sci 2024; 137:jcs261828. [PMID: 38690758 PMCID: PMC11190432 DOI: 10.1242/jcs.261828] [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: 11/23/2023] [Accepted: 04/24/2024] [Indexed: 05/03/2024] Open
Abstract
Exocytosis is a fundamental process used by eukaryotes to regulate the composition of the plasma membrane and facilitate cell-cell communication. To investigate exocytosis in neuronal morphogenesis, previously we developed computational tools with a graphical user interface to enable the automatic detection and analysis of exocytic events from fluorescence timelapse images. Although these tools were useful, we found the code was brittle and not easily adapted to different experimental conditions. Here, we developed and validated a robust and versatile toolkit, named pHusion, for the analysis of exocytosis, written in ImageTank, a graphical programming language that combines image visualization and numerical methods. We tested pHusion using a variety of imaging modalities and pH-sensitive fluorophores, diverse cell types and various exocytic markers, to generate a flexible and intuitive package. Using this system, we show that VAMP3-mediated exocytosis occurs 30-times more frequently in melanoma cells compared with primary oligodendrocytes, that VAMP2-mediated fusion events in mature rat hippocampal neurons are longer lasting than those in immature murine cortical neurons, and that exocytic events are clustered in space yet random in time in developing cortical neurons.
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Affiliation(s)
- Ellen C. O'Shaughnessy
- University of North Carolina at Chapel Hill, Department of Cell Biology and Physiology, Chapel Hill, NC 27599, USA
| | - Mable Lam
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Samantha E. Ryken
- University of North Carolina at Chapel Hill, Department of Cell Biology and Physiology, Chapel Hill, NC 27599, USA
| | - Theresa Wiesner
- NeuroCyto, Aix Marseille Université, CNRS, INP UMR7051, Marseille 13385, France
| | - Kimberly Lukasik
- University of North Carolina at Chapel Hill, Department of Cell Biology and Physiology, Chapel Hill, NC 27599, USA
| | - J. Bradley Zuchero
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | | | - David Adalsteinsson
- University of North Carolina at Chapel Hill, Department of Mathematics, Chapel Hill, NC 27599, USA
| | - Stephanie L. Gupton
- University of North Carolina at Chapel Hill, Department of Cell Biology and Physiology, Chapel Hill, NC 27599, USA
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2
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McFadden MH, Emeritt MB, Xu H, Cui Y, Leterrier C, Zala D, Venance L, Lenkei Z. Actomyosin-mediated inhibition of synaptic vesicle release under CB 1R activation. Transl Psychiatry 2024; 14:335. [PMID: 39168993 DOI: 10.1038/s41398-024-03017-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 04/16/2024] [Accepted: 07/08/2024] [Indexed: 08/23/2024] Open
Abstract
Long-term synaptic plasticity is critical for adaptive function of the brain, but presynaptic mechanisms of functional plasticity remain poorly understood. Here, we show that changes in synaptic efficacy induced by activation of the cannabinoid type-1 receptor (CB1R), one of the most widespread G-protein coupled receptors in the brain, requires contractility of the neuronal actomyosin cytoskeleton. Specifically, using a synaptophysin-pHluorin probe (sypH2), we show that inhibitors of non-muscle myosin II (NMII) ATPase as well as one of its upstream effectors Rho-associated kinase (ROCK) prevent the reduction of synaptic vesicle release induced by CB1R activation. Using 3D STORM super-resolution microscopy, we find that activation of CB1R induces a redistribution of synaptic vesicles within presynaptic boutons in an actomyosin dependent manner, leading to vesicle clustering within the bouton and depletion of synaptic vesicles from the active zone. We further show, using sypH2, that inhibitors of NMII and ROCK specifically restore the release of the readily releasable pool of synaptic vesicles from the inhibition induced by CB1R activation. Finally, using slice electrophysiology, we find that activation of both NMII and ROCK is necessary for the long-term, but not the short-term, form of CB1R induced synaptic plasticity at excitatory cortico-striatal synapses. We thus propose a novel mechanism underlying CB1R-induced plasticity, whereby CB1R activation leads to a contraction of the actomyosin cytoskeleton inducing a reorganization of the functional presynaptic vesicle pool, preventing vesicle release and inducing long-term depression.
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Affiliation(s)
- Maureen H McFadden
- Institut Pasteur, Université Paris Cité, Synapse and Circuit Dynamics Laboratory, CNRS UMR 3571, Paris, France
- Brain Plasticity Unit, ESPCI Paris, PSL Research University, CNRS, Paris, France
| | - Michel-Boris Emeritt
- Institute of Psychiatry and Neuroscience of Paris (IPNP), Université Paris Cité, INSERM U1266, Paris, France
| | - Hao Xu
- Dynamics and Pathophysiology of Neuronal Networks Team, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Yihui Cui
- Dynamics and Pathophysiology of Neuronal Networks Team, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | | | - Diana Zala
- Brain Plasticity Unit, ESPCI Paris, PSL Research University, CNRS, Paris, France
- Institute of Psychiatry and Neuroscience of Paris (IPNP), Université Paris Cité, INSERM U1266, Paris, France
| | - Laurent Venance
- Dynamics and Pathophysiology of Neuronal Networks Team, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Zsolt Lenkei
- Brain Plasticity Unit, ESPCI Paris, PSL Research University, CNRS, Paris, France.
- Institute of Psychiatry and Neuroscience of Paris (IPNP), Université Paris Cité, INSERM U1266, Paris, France.
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Kusumi A, Tsunoyama TA, Suzuki KGN, Fujiwara TK, Aladag A. Transient, nano-scale, liquid-like molecular assemblies coming of age. Curr Opin Cell Biol 2024; 89:102394. [PMID: 38963953 DOI: 10.1016/j.ceb.2024.102394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 06/02/2024] [Accepted: 06/06/2024] [Indexed: 07/06/2024]
Abstract
This review examines the dynamic mechanisms underlying cellular signaling, communication, and adhesion via transient, nano-scale, liquid-like molecular assemblies on the plasma membrane (PM). Traditional views posit that stable, solid-like molecular complexes perform these functions. However, advanced imaging reveals that many signaling and scaffolding proteins only briefly reside in these molecular complexes and that micron-scale protein assemblies on the PM, including cell adhesion structures and synapses, are likely made of archipelagoes of nanoliquid protein islands. Borrowing the concept of liquid-liquid phase separation to form micron-scale biocondensates, we propose that these nano-scale oligomers and assemblies are enabled by multiple weak but specific molecular interactions often involving intrinsically disordered regions. The signals from individual nanoliquid signaling complexes would occur as pulses. Single-molecule imaging emerges as a crucial technique for characterizing these transient nanoliquid assemblies on the PM, suggesting a shift toward a model where the fluidity of interactions underpins signal regulation and integration.
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Affiliation(s)
- Akihiro Kusumi
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan; Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan.
| | - Taka A Tsunoyama
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan
| | - Kenichi G N Suzuki
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan; Institute for Glyco-core Research (iGCORE), Gifu University, Gifu 501-1193, Japan; National Cancer Center Research Institute, Tokyo 104-0045, Japan
| | - Takahiro K Fujiwara
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan
| | - Amine Aladag
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan; Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan
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4
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Akshita C, Christian H, Aleksandr KA, Jakob R, Linda K, Luka G, Cristina RV, Emma JC, Jaqulin WN, Branislava R, Eleonora P, Sarah K, Silvio RO, Helge E, Jennifer MR, Dragomir M. Condensates of synaptic vesicles and synapsin are molecular beacons for actin sequestering and polymerization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.19.604346. [PMID: 39071264 PMCID: PMC11275919 DOI: 10.1101/2024.07.19.604346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Neuronal communication relies on precisely maintained synaptic vesicle (SV) clusters, which assemble via liquid-liquid phase separation (LLPS). This process requires synapsins, the major synaptic phosphoproteins, which are known to bind actin. The reorganization of SVs, synapsins and actin is a hallmark of synaptic activity, but their interplay is still unclear. Here we combined the reconstitution approaches and super-resolution imaging to dissect the roles of synapsin-SV condensates in the organization of the presynaptic actin cytoskeleton. Our data indicate that LLPS of synapsin initiates actin polymerization, allowing for SV:synapsin:actin assemblies to facilitate the mesoscale organization of SV clusters along axons mimicking the native presynaptic organization in both lamprey and mammalian synapses. Understanding the relationship between the actin network and synapsin-SVs condensates is an essential building block on a roadmap to unravel how coordinated neurotransmission along the axon enables circuit function and behavior.
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Affiliation(s)
- Chhabra Akshita
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
- Whitman Center, Marine Biological Laboratory, 02543 Woods Hole, MA, USA
| | - Hoffmann Christian
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
- Whitman Center, Marine Biological Laboratory, 02543 Woods Hole, MA, USA
| | - Korobeinikov A. Aleksandr
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Rentsch Jakob
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Kokwaro Linda
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
- Einstein Center for Neuroscience, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, 10117 Berlin, Germany
| | - Gnidovec Luka
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Román-Vendrell Cristina
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, 02543 Woods Hole, MA, USA
| | - Johnson C. Emma
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, 02543 Woods Hole, MA, USA
| | - Wallace N. Jaqulin
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, 02543 Woods Hole, MA, USA
| | - Rankovic Branislava
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
- Whitman Center, Marine Biological Laboratory, 02543 Woods Hole, MA, USA
| | - Perego Eleonora
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Köster Sarah
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Rizzoli O. Silvio
- Institute for Neuro- and Sensory Physiology, University Medical Center Göttingen, 37073, Göttingen, Germany
| | - Ewers Helge
- Whitman Center, Marine Biological Laboratory, 02543 Woods Hole, MA, USA
| | - Morgan R. Jennifer
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, 02543 Woods Hole, MA, USA
| | - Milovanovic Dragomir
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
- Whitman Center, Marine Biological Laboratory, 02543 Woods Hole, MA, USA
- Einstein Center for Neuroscience, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, 10117 Berlin, Germany
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5
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Sun C. Single-Molecule-Resolution Approaches in Synaptic Biology. J Phys Chem B 2024; 128:3061-3068. [PMID: 38513216 DOI: 10.1021/acs.jpcb.3c08026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
Synapses between neurons are the primary loci for information transfer and storage in the brain. An individual neuron, alone, can make over 10000 synaptic contacts. It is, however, not easy to investigate what goes on locally within a synapse because many synaptic compartments are only a few hundred nanometers wide in size─close to the diffraction limit of light. To observe the biomolecular machinery and processes within synapses, in situ single-molecule techniques are emerging as powerful tools. Guided by important biological questions, this Perspective will highlight recent advances in using these techniques to obtain in situ measurements of synaptic molecules in three aspects: the cell-biological machinery within synapses, the synaptic architecture, and the synaptic neurotransmitter receptors. These advances showcase the increasing importance of single-molecule-resolution techniques for accessing subcellular biophysical and biomolecular information related to the brain.
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Affiliation(s)
- Chao Sun
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, 8000 Aarhus C, Denmark
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6
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Oevel K, Hohensee S, Kumar A, Rosas-Brugada I, Bartolini F, Soykan T, Haucke V. Rho GTPase signaling and mDia facilitate endocytosis via presynaptic actin. eLife 2024; 12:RP92755. [PMID: 38502163 PMCID: PMC10950329 DOI: 10.7554/elife.92755] [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] [Indexed: 03/20/2024] Open
Abstract
Neurotransmission at synapses is mediated by the fusion and subsequent endocytosis of synaptic vesicle membranes. Actin has been suggested to be required for presynaptic endocytosis but the mechanisms that control actin polymerization and its mode of action within presynaptic nerve terminals remain poorly understood. We combine optical recordings of presynaptic membrane dynamics and ultrastructural analysis with genetic and pharmacological manipulations to demonstrate that presynaptic endocytosis is controlled by actin regulatory diaphanous-related formins mDia1/3 and Rho family GTPase signaling in mouse hippocampal neurons. We show that impaired presynaptic actin assembly in the near absence of mDia1/3 and reduced RhoA activity is partly compensated by hyperactivation of Rac1. Inhibition of Rac1 signaling further aggravates impaired presynaptic endocytosis elicited by loss of mDia1/3. Our data suggest that interdependent mDia1/3-Rho and Rac1 signaling pathways cooperatively act to facilitate synaptic vesicle endocytosis by controlling presynaptic F-actin.
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Affiliation(s)
- Kristine Oevel
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)BerlinGermany
| | - Svea Hohensee
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)BerlinGermany
| | - Atul Kumar
- Department of Pathology and Cell Biology, Columbia University Medical CenterNew York CityUnited States
| | | | - Francesca Bartolini
- Department of Pathology and Cell Biology, Columbia University Medical CenterNew York CityUnited States
| | - Tolga Soykan
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)BerlinGermany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)BerlinGermany
- Faculty of Biology, Chemistry, Pharmacy, Freie Universität BerlinBerlinGermany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin BerlinBerlinGermany
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7
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Parra-Rivas LA, Madhivanan K, Aulston BD, Wang L, Prakashchand DD, Boyer NP, Saia-Cereda VM, Branes-Guerrero K, Pizzo DP, Bagchi P, Sundar VS, Tang Y, Das U, Scott DA, Rangamani P, Ogawa Y, Subhojit Roy. Serine-129 phosphorylation of α-synuclein is an activity-dependent trigger for physiologic protein-protein interactions and synaptic function. Neuron 2023; 111:4006-4023.e10. [PMID: 38128479 PMCID: PMC10766085 DOI: 10.1016/j.neuron.2023.11.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 10/08/2023] [Accepted: 11/19/2023] [Indexed: 12/23/2023]
Abstract
Phosphorylation of α-synuclein at the serine-129 site (α-syn Ser129P) is an established pathologic hallmark of synucleinopathies and a therapeutic target. In physiologic states, only a fraction of α-syn is phosphorylated at this site, and most studies have focused on the pathologic roles of this post-translational modification. We found that unlike wild-type (WT) α-syn, which is widely expressed throughout the brain, the overall pattern of α-syn Ser129P is restricted, suggesting intrinsic regulation. Surprisingly, preventing Ser129P blocked activity-dependent synaptic attenuation by α-syn-thought to reflect its normal function. Exploring mechanisms, we found that neuronal activity augments Ser129P, which is a trigger for protein-protein interactions that are necessary for mediating α-syn function at the synapse. AlphaFold2-driven modeling and membrane-binding simulations suggest a scenario where Ser129P induces conformational changes that facilitate interactions with binding partners. Our experiments offer a new conceptual platform for investigating the role of Ser129 in synucleinopathies, with implications for drug development.
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Affiliation(s)
- Leonardo A Parra-Rivas
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Kayalvizhi Madhivanan
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - Brent D Aulston
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - Lina Wang
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - Dube Dheeraj Prakashchand
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, USA
| | - Nicholas P Boyer
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - Veronica M Saia-Cereda
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - Kristen Branes-Guerrero
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - Donald P Pizzo
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - Pritha Bagchi
- Emory Integrated Proteomics Core, Emory University, Atlanta, GA, USA
| | - V S Sundar
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - Yong Tang
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - Utpal Das
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA; Department of Neurosciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - David A Scott
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, USA
| | - Yuki Ogawa
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Subhojit Roy
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA; Department of Neurosciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA.
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Ermanoska B, Rodal AA. Non-muscle myosin II regulates presynaptic actin assemblies and neuronal mechanobiology. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.10.566609. [PMID: 38014140 PMCID: PMC10680633 DOI: 10.1101/2023.11.10.566609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Neuromuscular junctions (NMJs) are evolutionarily ancient, specialized contacts between neurons and muscles. Axons and NMJs must endure mechanical strain through a lifetime of muscle contraction, making them vulnerable to aging and neurodegenerative conditions. However, cellular strategies for mitigating this mechanical stress remain unknown. In this study, we used Drosophila larval NMJs to investigate the role of actin and myosin (actomyosin)-mediated contractility in generating and responding to cellular forces at the neuron-muscle interface. We identified a new long-lived, low-turnover presynaptic actin core traversing the NMJ, which partly co-localizes with non-muscle myosin II (NMII). Neuronal RNAi of NMII induced disorganization of this core, suggesting that this structure might have contractile properties. Interestingly, neuronal RNAi of NMII also decreased NMII levels in the postsynaptic muscle proximal to neurons, suggesting that neuronal actomyosin rearrangements propagate their effects trans-synaptically. We also observed reduced Integrin levels upon NMII knockdown, indicating that neuronal actomyosin disruption triggers rearrangements of Integrin-mediated connections between neurons and surrounding muscle tissue. In summary, our study identifies a previously uncharacterized presynaptic actomyosin subpopulation that upholds the neuronal mechanical continuum, transmits signals to adjacent muscle tissue, and collaborates with Integrin receptors to govern the mechanobiology of the neuromuscular junction.
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Parkes M, Landers NL, Gramlich MW. Recently recycled synaptic vesicles use multi-cytoskeletal transport and differential presynaptic capture probability to establish a retrograde net flux during ISVE in central neurons. Front Cell Dev Biol 2023; 11:1286915. [PMID: 38020880 PMCID: PMC10657820 DOI: 10.3389/fcell.2023.1286915] [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: 09/01/2023] [Accepted: 10/18/2023] [Indexed: 12/01/2023] Open
Abstract
Presynapses locally recycle synaptic vesicles to efficiently communicate information. During use and recycling, proteins on the surface of synaptic vesicles break down and become less efficient. In order to maintain efficient presynaptic function and accommodate protein breakdown, new proteins are regularly produced in the soma and trafficked to presynaptic locations where they replace older protein-carrying vesicles. Maintaining a balance of new proteins and older proteins is thus essential for presynaptic maintenance and plasticity. While protein production and turnover have been extensively studied, it is still unclear how older synaptic vesicles are trafficked back to the soma for recycling in order to maintain balance. In the present study, we use a combination of fluorescence microscopy, hippocampal cell cultures, and computational analyses to determine the mechanisms that mediate older synaptic vesicle trafficking back to the soma. We show that synaptic vesicles, which have recently undergone exocytosis, can differentially utilize either the microtubule or the actin cytoskeleton networks. We show that axonally trafficked vesicles traveling with higher speeds utilize the microtubule network and are less likely to be captured by presynapses, while slower vesicles utilize the actin network and are more likely to be captured by presynapses. We also show that retrograde-driven vesicles are less likely to be captured by a neighboring presynapse than anterograde-driven vesicles. We show that the loss of synaptic vesicle with bound molecular motor myosin V is the mechanism that differentiates whether vesicles will utilize the microtubule or actin networks. Finally, we present a theoretical framework of how our experimentally observed retrograde vesicle trafficking bias maintains the balance with previously observed rates of new vesicle trafficking from the soma.
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