1
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Lamanna J, Gloria G, Villa A, Malgaroli A. Anomalous diffusion of synaptic vesicles and its influences on spontaneous and evoked neurotransmission. J Physiol 2024; 602:2873-2898. [PMID: 38723211 DOI: 10.1113/jp284926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 04/22/2024] [Indexed: 06/15/2024] Open
Abstract
Neurons in the central nervous system communicate with each other by activating billions of tiny synaptic boutons distributed along their fine axons. These presynaptic varicosities are very crowded environments, comprising hundreds of synaptic vesicles. Only a fraction of these vesicles can be recruited in a single release episode, either spontaneous or evoked by action potentials. Since the seminal work by Fatt and Katz, spontaneous release has been modelled as a memoryless process. Nevertheless, at central synapses, experimental evidence indicates more complex features, including non-exponential distributions of release intervals and power-law behaviour in their rate. To describe these features, we developed a probabilistic model of spontaneous release based on Brownian motion of synaptic vesicles in the presynaptic environment. To account for different diffusion regimes, we based our simulations on fractional Brownian motion. We show that this model can predict both deviation from the Poisson hypothesis and power-law features in experimental quantal release series, thus suggesting that the vesicular motion by diffusion could per se explain the emergence of these properties. We demonstrate the efficacy of our modelling approach using electrophysiological recordings at single synaptic boutons and ultrastructural data. When this approach was used to simulate evoked responses, we found that the replenishment of the readily releasable pool driven by Brownian motion of vesicles can reproduce the characteristic binomial release distributions seen experimentally. We believe that our modelling approach supports the idea that vesicle diffusion and readily releasable pool dynamics are crucial factors for the physiological functioning of neuronal communication. KEY POINTS: We developed a new probabilistic model of spontaneous and evoked vesicle fusion based on simple biophysical assumptions, including the motion of vesicles before they dock to the release site. We provide closed-form equations for the interval distribution of spontaneous releases in the special case of Brownian diffusion of vesicles, showing that a power-law heavy tail is generated. Fractional Brownian motion (fBm) was exploited to simulate anomalous vesicle diffusion, including directed and non-directed motion, by varying the Hurst exponent. We show that our model predicts non-linear features observed in experimental spontaneous quantal release series as well as ultrastructural data of synaptic vesicles spatial distribution. Evoked exocytosis based on a diffusion-replenished readily releasable pool might explain the emergence of power-law behaviour in neuronal activity.
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Affiliation(s)
- Jacopo Lamanna
- Center for Behavioral Neuroscience and Communication (BNC), Vita-Salute San Raffaele University, Milan, Italy
- Faculty of Psychology, Vita-Salute San Raffaele University, Milan, Italy
| | - Giulia Gloria
- Center for Behavioral Neuroscience and Communication (BNC), Vita-Salute San Raffaele University, Milan, Italy
| | | | - Antonio Malgaroli
- Center for Behavioral Neuroscience and Communication (BNC), Vita-Salute San Raffaele University, Milan, Italy
- Faculty of Psychology, Vita-Salute San Raffaele University, Milan, Italy
- San Raffaele Turro, IRCCS Ospedale San Raffaele, Milan, Italy
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2
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Hepburn I, Lallouette J, Chen W, Gallimore AR, Nagasawa-Soeda SY, De Schutter E. Vesicle and reaction-diffusion hybrid modeling with STEPS. Commun Biol 2024; 7:573. [PMID: 38750123 PMCID: PMC11096338 DOI: 10.1038/s42003-024-06276-5] [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: 09/11/2023] [Accepted: 05/01/2024] [Indexed: 05/18/2024] Open
Abstract
Vesicles carry out many essential functions within cells through the processes of endocytosis, exocytosis, and passive and active transport. This includes transporting and delivering molecules between different parts of the cell, and storing and releasing neurotransmitters in neurons. To date, computational simulation of these key biological players has been rather limited and has not advanced at the same pace as other aspects of cell modeling, restricting the realism of computational models. We describe a general vesicle modeling tool that has been designed for wide application to a variety of cell models, implemented within our software STochastic Engine for Pathway Simulation (STEPS), a stochastic reaction-diffusion simulator that supports realistic reconstructions of cell tissue in tetrahedral meshes. The implementation is validated in an extensive test suite, parallel performance is demonstrated in a realistic synaptic bouton model, and example models are visualized in a Blender extension module.
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Affiliation(s)
- Iain Hepburn
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-son, Okinawa, Japan
| | - Jules Lallouette
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-son, Okinawa, Japan
| | - Weiliang Chen
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-son, Okinawa, Japan
| | - Andrew R Gallimore
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-son, Okinawa, Japan
| | - Sarah Y Nagasawa-Soeda
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-son, Okinawa, Japan
| | - Erik De Schutter
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-son, Okinawa, Japan.
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3
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Longfield SF, Gormal RS, Feller M, Parutto P, Reingruber J, Wallis TP, Joensuu M, Augustine GJ, Martínez-Mármol R, Holcman D, Meunier FA. Synapsin 2a tetramerisation selectively controls the presynaptic nanoscale organisation of reserve synaptic vesicles. Nat Commun 2024; 15:2217. [PMID: 38472171 PMCID: PMC10933366 DOI: 10.1038/s41467-024-46256-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 02/21/2024] [Indexed: 03/14/2024] Open
Abstract
Neurotransmitter release relies on the regulated fusion of synaptic vesicles (SVs) that are tightly packed within the presynaptic bouton of neurons. The mechanism by which SVs are clustered at the presynapse, while preserving their ability to dynamically recycle to support neuronal communication, remains unknown. Synapsin 2a (Syn2a) tetramerization has been suggested as a potential clustering mechanism. Here, we used Dual-pulse sub-diffractional Tracking of Internalised Molecules (DsdTIM) to simultaneously track single SVs from the recycling and the reserve pools, in live hippocampal neurons. The reserve pool displays a lower presynaptic mobility compared to the recycling pool and is also present in the axons. Triple knockout of Synapsin 1-3 genes (SynTKO) increased the mobility of reserve pool SVs. Re-expression of wild-type Syn2a (Syn2aWT), but not the tetramerization-deficient mutant K337Q (Syn2aK337Q), fully rescued these effects. Single-particle tracking revealed that Syn2aK337QmEos3.1 exhibited altered activity-dependent presynaptic translocation and nanoclustering. Therefore, Syn2a tetramerization controls its own presynaptic nanoclustering and thereby contributes to the dynamic immobilisation of the SV reserve pool.
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Affiliation(s)
- Shanley F Longfield
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rachel S Gormal
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Matis Feller
- Group of Data Modelling and Computational Biology, IBENS, Ecole Normale Superieure, 75005, Paris, France
| | - Pierre Parutto
- Group of Data Modelling and Computational Biology, IBENS, Ecole Normale Superieure, 75005, Paris, France
| | - Jürgen Reingruber
- Group of Data Modelling and Computational Biology, IBENS, Ecole Normale Superieure, 75005, Paris, France
| | - Tristan P Wallis
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Merja Joensuu
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia
| | | | - Ramón Martínez-Mármol
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - David Holcman
- Group of Data Modelling and Computational Biology, IBENS, Ecole Normale Superieure, 75005, Paris, France
- Department of Applied Mathematics and Theoretical Physics (DAMPT) visitor, University of Cambridge, and Churchill College, CB30DS, Cambridge, UK
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia.
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4
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Alfken J, Neuhaus C, Major A, Taskina A, Hoffmann C, Ganzella M, Petrovic A, Zwicker D, Fernández-Busnadiego R, Jahn R, Milovanovic D, Salditt T. Vesicle condensation induced by synapsin: condensate size, geometry, and vesicle shape deformations. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2024; 47:8. [PMID: 38270681 DOI: 10.1140/epje/s10189-023-00404-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 12/28/2023] [Indexed: 01/26/2024]
Abstract
We study the formation of vesicle condensates induced by the protein synapsin, as a cell-free model system mimicking vesicle pool formation in the synapse. The system can be considered as an example of liquid-liquid phase separation (LLPS) in biomolecular fluids, where one phase is a complex fluid itself consisting of vesicles and a protein network. We address the pertinent question why the LLPS is self-limiting and stops at a certain size, i.e., why macroscopic phase separation is prevented. Using fluorescence light microscopy, we observe different morphologies of the condensates (aggregates) depending on the protein-to-lipid ratio. Cryogenic electron microscopy then allows us to resolve individual vesicle positions and shapes in a condensate and notably the size and geometry of adhesion zones between vesicles. We hypothesize that the membrane tension induced by already formed adhesion zones then in turn limits the capability of vesicles to bind additional vesicles, resulting in a finite condensate size. In a simple numerical toy model we show that this effect can be accounted for by redistribution of effective binding particles on the vesicle surface, accounting for the synapsin-induced adhesion zone.
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Affiliation(s)
- Jette Alfken
- Institut für Röntgenphysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany
| | - Charlotte Neuhaus
- Institut für Röntgenphysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany
| | - András Major
- Institut für Röntgenphysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany
| | - Alyona Taskina
- Institut für Röntgenphysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany
- Theorie Biologischer Flüssigkeiten, Max-Planck-Institut für Dynamik und Selbstorganisation, Am Fassberg 11, 37077, Göttingen, Germany
| | - Christian Hoffmann
- Molekulare Neurowissenschaften, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Charitéplatz 1, 10117, Berlin, Germany
| | - Marcelo Ganzella
- Labor für Neurobiologie, Max-Planck-Institut für multidisziplinäre Naturwissenschaften, Am Fassberg 11, 37077, Göttingen, Germany
| | - Arsen Petrovic
- Institut für Neuropathologie, Universitätsmedizin Göttingen, Justus-von-Liebig-Weg 11, 37077, Göttingen, Germany
| | - David Zwicker
- Theorie Biologischer Flüssigkeiten, Max-Planck-Institut für Dynamik und Selbstorganisation, Am Fassberg 11, 37077, Göttingen, Germany
| | - Rubén Fernández-Busnadiego
- Institut für Neuropathologie, Universitätsmedizin Göttingen, Justus-von-Liebig-Weg 11, 37077, Göttingen, Germany
| | - Reinhard Jahn
- Labor für Neurobiologie, Max-Planck-Institut für multidisziplinäre Naturwissenschaften, Am Fassberg 11, 37077, Göttingen, Germany
| | - Dragomir Milovanovic
- Molekulare Neurowissenschaften, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Charitéplatz 1, 10117, Berlin, Germany
| | - Tim Salditt
- Institut für Röntgenphysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany.
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5
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Wallace JN, Crockford ZC, Román-Vendrell C, Brady EB, Hoffmann C, Vargas KJ, Potcoava M, Wegman ME, Alford ST, Milovanovic D, Morgan JR. Excess phosphoserine-129 α-synuclein induces synaptic vesicle trafficking and declustering defects at a vertebrate synapse. Mol Biol Cell 2024; 35:ar10. [PMID: 37991902 PMCID: PMC10881165 DOI: 10.1091/mbc.e23-07-0269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 11/06/2023] [Accepted: 11/06/2023] [Indexed: 11/24/2023] Open
Abstract
α-Synuclein is a presynaptic protein that regulates synaptic vesicle (SV) trafficking. In Parkinson's disease (PD) and dementia with Lewy bodies (DLB), α-synuclein aberrantly accumulates throughout neurons, including at synapses. During neuronal activity, α-synuclein is reversibly phosphorylated at serine 129 (pS129). While pS129 comprises ∼4% of total α-synuclein under physiological conditions, it dramatically increases in PD and DLB brains. The impacts of excess pS129 on synaptic function are currently unknown. We show here that compared with wild-type (WT) α-synuclein, pS129 exhibits increased binding and oligomerization on synaptic membranes and enhanced vesicle "microclustering" in vitro. Moreover, when acutely injected into lamprey reticulospinal axons, excess pS129 α-synuclein robustly localized to synapses and disrupted SV trafficking in an activity-dependent manner, as assessed by ultrastructural analysis. Specifically, pS129 caused a declustering and dispersion of SVs away from the synaptic vicinity, leading to a significant loss of total synaptic membrane. Live imaging further revealed altered SV cycling, as well as microclusters of recently endocytosed SVs moving away from synapses. Thus, excess pS129 caused an activity-dependent inhibition of SV trafficking via altered vesicle clustering/reclustering. This work suggests that accumulation of pS129 at synapses in diseases like PD and DLB could have profound effects on SV dynamics.
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Affiliation(s)
| | | | | | - Emily B. Brady
- Eugene Bell Center for Regenerative Biology and Tissue Engineering, and
| | - Christian Hoffmann
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Karina J. Vargas
- Eugene Bell Center for Regenerative Biology and Tissue Engineering, and
- Department of Cell Biology, University of Pittsburgh, PA 15261
| | - Mariana Potcoava
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612
| | | | - Simon T. Alford
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612
| | - Dragomir Milovanovic
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
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6
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Li D, Ai S, Huang C, Liu ZH, Wang HL. Icariin rescues developmental BPA exposure induced spatial memory deficits in rats. Toxicol Appl Pharmacol 2024; 482:116776. [PMID: 38043803 DOI: 10.1016/j.taap.2023.116776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 11/23/2023] [Accepted: 11/27/2023] [Indexed: 12/05/2023]
Abstract
Bisphenol A (BPA) has been implicated in cognitive impairment. Icariin is the main active ingredient extracted from Epimedium Herb with protective function of nervous system. However, the potential therapeutic effects of Icariin on spatial memory deficits induced by developmental BPA exposure in Sprague-Dawley rats have not been investigated. This study investigated the therapeutic effect of Icariin (10 mg/kg/day, from postnatal day (PND) 21 to PND 60 by gavage) on spatial memory deficits in rat induced by developmental BPA exposure (1 mg/kg/day, from embryonic to PND 60), demonstrating that Icariin can markedly improve spatial memory in BPA-exposed rat. Furthermore, intra-gastric administration of Icariin could attenuate abnormal hippocampal cell dispersion and loss, improved the dendritic spine density and Nissl bodies. Moreover, Icariin reversed BPA induced reduction of frequency of miniature excitatory postsynaptic currents(mEPSC) and decrease of Vesicular glutamate transporter 1(VGlut1). Collectively, Icariin could effectively rescue BPA-induced spatial memory impairment in male rats by preventing cell loss and reduction of dendritic spines in the hippocampus. In addition, we also found that VGlut1 is a critical target in the repair of BPA-induced spatial memory by Icariin. Thus, Icariin may be a promising therapeutic agent to attenuate BPA-induced spatial memory deficits.
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Affiliation(s)
- Danyang Li
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, Anhui Province 230009, China
| | - Shu Ai
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, Anhui Province 230009, China
| | - Chengqing Huang
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, Anhui Province 230009, China
| | - Zhi-Hua Liu
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, Anhui Province 230009, China.
| | - Hui-Li Wang
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, Anhui Province 230009, China.
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7
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Hoffmann C, Milovanovic D. Dipping contacts - a novel type of contact site at the interface between membraneless organelles and membranes. J Cell Sci 2023; 136:jcs261413. [PMID: 38149872 PMCID: PMC10785658 DOI: 10.1242/jcs.261413] [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: 12/28/2023] Open
Abstract
Liquid-liquid phase separation is a major mechanism for organizing macromolecules, particularly proteins with intrinsically disordered regions, in compartments not limited by a membrane or a scaffold. The cell can therefore be perceived as a complex emulsion containing many of these membraneless organelles, also referred to as biomolecular condensates, together with numerous membrane-bound organelles. It is currently unclear how such a complex concoction operates to allow for intracellular trafficking, signaling and metabolic processes to occur with high spatiotemporal precision. Based on experimental observations of synaptic vesicle condensates - a membraneless organelle that is in fact packed with membranes - we present here the framework of dipping contacts: a novel type of contact site between membraneless organelles and membranes. In this Hypothesis, we propose that our framework of dipping contacts can serve as a foundation to investigate the interface that couples the diffusion and material properties of condensates to biochemical processes occurring in membranes. The identity and regulation of this interface is especially critical in the case of neurodegenerative diseases, where aberrant inclusions of misfolded proteins and damaged organelles underlie cellular pathology.
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Affiliation(s)
- Christian Hoffmann
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543, USA
- National Center for X-ray Tomography, Advanced Light Source, Berkeley, CA 94720, USA
- Einstein Center for Neuroscience, Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität Berlin and Berlin Institute of Health, 10117 Berlin, Germany
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8
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Ramšak M, Ramirez DA, Hough LE, Shirts MR, Vidmar S, Eleršič Filipič K, Anderluh G, Jerala R. Programmable de novo designed coiled coil-mediated phase separation in mammalian cells. Nat Commun 2023; 14:7973. [PMID: 38042897 PMCID: PMC10693550 DOI: 10.1038/s41467-023-43742-w] [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: 06/29/2023] [Accepted: 11/17/2023] [Indexed: 12/04/2023] Open
Abstract
Membraneless liquid compartments based on phase-separating biopolymers have been observed in diverse cell types and attributed to weak multivalent interactions predominantly based on intrinsically disordered domains. The design of liquid-liquid phase separated (LLPS) condensates based on de novo designed tunable modules that interact in a well-understood, controllable manner could improve our understanding of this phenomenon and enable the introduction of new features. Here we report the construction of CC-LLPS in mammalian cells, based on designed coiled-coil (CC) dimer-forming modules, where the stability of CC pairs, their number, linkers, and sequential arrangement govern the transition between diffuse, liquid and immobile condensates and are corroborated by coarse-grained molecular simulations. Through modular design, we achieve multiple coexisting condensates, chemical regulation of LLPS, condensate fusion, formation from either one or two polypeptide components or LLPS regulation by a third polypeptide chain. These findings provide further insights into the principles underlying LLPS formation and a design platform for controlling biological processes.
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Affiliation(s)
- Maruša Ramšak
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, Ljubljana, Slovenia
- Interdisciplinary doctoral study of biomedicine, Medical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Dominique A Ramirez
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Loren E Hough
- Department of Physics and BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA
| | - Michael R Shirts
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, USA
| | - Sara Vidmar
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, Ljubljana, Slovenia
- Interdisciplinary doctoral study of biomedicine, Medical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Kristina Eleršič Filipič
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Gregor Anderluh
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Roman Jerala
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, Ljubljana, Slovenia.
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9
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Longfield SF, Mollazade M, Wallis TP, Gormal RS, Joensuu M, Wark JR, van Waardenberg AJ, Small C, Graham ME, Meunier FA, Martínez-Mármol R. Tau forms synaptic nano-biomolecular condensates controlling the dynamic clustering of recycling synaptic vesicles. Nat Commun 2023; 14:7277. [PMID: 37949856 PMCID: PMC10638352 DOI: 10.1038/s41467-023-43130-4] [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: 07/02/2022] [Accepted: 11/01/2023] [Indexed: 11/12/2023] Open
Abstract
Neuronal communication relies on the release of neurotransmitters from various populations of synaptic vesicles. Despite displaying vastly different release probabilities and mobilities, the reserve and recycling pool of vesicles co-exist within a single cluster suggesting that small synaptic biomolecular condensates could regulate their nanoscale distribution. Here, we performed a large-scale activity-dependent phosphoproteome analysis of hippocampal neurons in vitro and identified Tau as a highly phosphorylated and disordered candidate protein. Single-molecule super-resolution microscopy revealed that Tau undergoes liquid-liquid phase separation to generate presynaptic nanoclusters whose density and number are regulated by activity. This activity-dependent diffusion process allows Tau to translocate into the presynapse where it forms biomolecular condensates, to selectively control the mobility of recycling vesicles. Tau, therefore, forms presynaptic nano-biomolecular condensates that regulate the nanoscale organization of synaptic vesicles in an activity-dependent manner.
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Affiliation(s)
- Shanley F Longfield
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland; St Lucia Campus, Brisbane, QLD, 4072, Australia
| | - Mahdie Mollazade
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland; St Lucia Campus, Brisbane, QLD, 4072, Australia
| | - Tristan P Wallis
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland; St Lucia Campus, Brisbane, QLD, 4072, Australia
| | - Rachel S Gormal
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland; St Lucia Campus, Brisbane, QLD, 4072, Australia
| | - Merja Joensuu
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland; St Lucia Campus, Brisbane, QLD, 4072, Australia
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland; St Lucia Campus, Brisbane, QLD, 4072, Australia
| | - Jesse R Wark
- Synapse Proteomics, Children's Medical Research Institute (CMRI), The University of Sydney, 214 Hawkesbury Road, Westmead, NSW, 2145, Australia
| | | | - Christopher Small
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland; St Lucia Campus, Brisbane, QLD, 4072, Australia
| | - Mark E Graham
- Synapse Proteomics, Children's Medical Research Institute (CMRI), The University of Sydney, 214 Hawkesbury Road, Westmead, NSW, 2145, Australia
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland; St Lucia Campus, Brisbane, QLD, 4072, Australia.
- School of Biomedical Science, The University of Queensland; St Lucia Campus, Brisbane, QLD, 4072, Australia.
| | - Ramón Martínez-Mármol
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland; St Lucia Campus, Brisbane, QLD, 4072, Australia.
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10
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Li Q, Song Q, Guo W, Cao Y, Cui X, Chen D, Shum HC. Synthetic Membraneless Droplets for Synaptic-Like Clustering of Lipid Vesicles. Angew Chem Int Ed Engl 2023; 62:e202313096. [PMID: 37728515 DOI: 10.1002/anie.202313096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 09/19/2023] [Accepted: 09/20/2023] [Indexed: 09/21/2023]
Abstract
In eukaryotic cells, the membraneless organelles (MLOs) formed via liquid-liquid phase separation (LLPS) are found to interact intimately with membranous organelles (MOs). One major mode is the clustering of MOs by MLOs, such as the formation of clusters of synaptic vesicles at nerve terminals mediated by the synapsin-rich MLOs. Aqueous droplets, including complex coacervates and aqueous two-phase systems, have been plausible MLO-mimics to emulate or elucidate biological processes. However, neither of them can cluster lipid vesicles (LVs) like MLOs. In this work, we develop a synthetic droplet assembled from a combination of two different interactions underlying the formation of these two droplets, namely, associative and segregative interactions, which we call segregative-associative (SA) droplets. The SA droplets cluster and disperse LVs recapitulating the key functional features of synapsin condensates, which can be attributed to the weak electrostatic interaction environment provided by SA droplets. This work suggests LLPS with combined segregative and associative interactions as a possible route for synaptic clustering of lipid vesicles and highlights SA droplets as plausible MLO-mimics and models for studying and mimicking related cellular dynamics.
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Affiliation(s)
- Qingchuan Li
- School of Chemistry & Chemical Engineering, National Engineering Research Center for Colloidal Materials, Shandong University, 27 Shanda Nanlu, Jinan, Shandong, P.R.China
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Shatin, New Territories, Hong Kong (SAR), Hong Kong, China
| | - Qingchun Song
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Wei Guo
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Shatin, New Territories, Hong Kong (SAR), Hong Kong, China
| | - Yang Cao
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Xinyu Cui
- Department of Public Health, Mudanjiang Medical University, Mudanjiang, 157000, P. R. China
| | - Dairong Chen
- School of Chemistry & Chemical Engineering, National Engineering Research Center for Colloidal Materials, Shandong University, 27 Shanda Nanlu, Jinan, Shandong, P.R.China
| | - Ho Cheung Shum
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Shatin, New Territories, Hong Kong (SAR), Hong Kong, China
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11
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Carter-Fenk K, Liu M, Pujal L, Loipersberger M, Tsanai M, Vernon RM, Forman-Kay JD, Head-Gordon M, Heidar-Zadeh F, Head-Gordon T. The Energetic Origins of Pi-Pi Contacts in Proteins. J Am Chem Soc 2023; 145. [PMID: 37917924 PMCID: PMC10655088 DOI: 10.1021/jacs.3c09198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 10/04/2023] [Accepted: 10/05/2023] [Indexed: 11/04/2023]
Abstract
Accurate potential energy models of proteins must describe the many different types of noncovalent interactions that contribute to a protein's stability and structure. Pi-pi contacts are ubiquitous structural motifs in all proteins, occurring between aromatic and nonaromatic residues and play a nontrivial role in protein folding and in the formation of biomolecular condensates. Guided by a geometric criterion for isolating pi-pi contacts from classical molecular dynamics simulations of proteins, we use quantum mechanical energy decomposition analysis to determine the molecular interactions that stabilize different pi-pi contact motifs. We find that neutral pi-pi interactions in proteins are dominated by Pauli repulsion and London dispersion rather than repulsive quadrupole electrostatics, which is central to the textbook Hunter-Sanders model. This results in a notable lack of variability in the interaction profiles of neutral pi-pi contacts even with extreme changes in the dielectric medium, explaining the prevalence of pi-stacked arrangements in and between proteins. We also find interactions involving pi-containing anions and cations to be extremely malleable, interacting like neutral pi-pi contacts in polar media and like typical ion-pi interactions in nonpolar environments. Like-charged pairs such as arginine-arginine contacts are particularly sensitive to the polarity of their immediate surroundings and exhibit canonical pi-pi stacking behavior only if the interaction is mediated by environmental effects, such as aqueous solvation.
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Affiliation(s)
- Kevin Carter-Fenk
- Kenneth
S. Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Meili Liu
- Kenneth
S. Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Department
of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Leila Pujal
- Department
of Chemistry, Queen’s University, Kingston, Ontario K7L 3N6, Canada
| | - Matthias Loipersberger
- Kenneth
S. Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Maria Tsanai
- Kenneth
S. Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Robert M. Vernon
- Molecular
Medicine Program, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
- Department
of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Julie D. Forman-Kay
- Molecular
Medicine Program, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
- Department
of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Martin Head-Gordon
- Kenneth
S. Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Farnaz Heidar-Zadeh
- Department
of Chemistry, Queen’s University, Kingston, Ontario K7L 3N6, Canada
- Center
for Molecular Modeling (CMM), Ghent University, 9052 Zwijnaarde, Belgium
| | - Teresa Head-Gordon
- Kenneth
S. Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Department
of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States
- Department
of Bioengineering, University of California, Berkeley, California 94720, United States
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12
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Hoffmann C, Rentsch J, Tsunoyama TA, Chhabra A, Aguilar Perez G, Chowdhury R, Trnka F, Korobeinikov AA, Shaib AH, Ganzella M, Giannone G, Rizzoli SO, Kusumi A, Ewers H, Milovanovic D. Synapsin condensation controls synaptic vesicle sequestering and dynamics. Nat Commun 2023; 14:6730. [PMID: 37872159 PMCID: PMC10593750 DOI: 10.1038/s41467-023-42372-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 10/09/2023] [Indexed: 10/25/2023] Open
Abstract
Neuronal transmission relies on the regulated secretion of neurotransmitters, which are packed in synaptic vesicles (SVs). Hundreds of SVs accumulate at synaptic boutons. Despite being held together, SVs are highly mobile, so that they can be recruited to the plasma membrane for their rapid release during neuronal activity. However, how such confinement of SVs corroborates with their motility remains unclear. To bridge this gap, we employ ultrafast single-molecule tracking (SMT) in the reconstituted system of native SVs and in living neurons. SVs and synapsin 1, the most highly abundant synaptic protein, form condensates with liquid-like properties. In these condensates, synapsin 1 movement is slowed in both at short (i.e., 60-nm) and long (i.e., several hundred-nm) ranges, suggesting that the SV-synapsin 1 interaction raises the overall packing of the condensate. Furthermore, two-color SMT and super-resolution imaging in living axons demonstrate that synapsin 1 drives the accumulation of SVs in boutons. Even the short intrinsically-disordered fragment of synapsin 1 was sufficient to restore the native SV motility pattern in synapsin triple knock-out animals. Thus, synapsin 1 condensation is sufficient to guarantee reliable confinement and motility of SVs, allowing for the formation of mesoscale domains of SVs at synapses in vivo.
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Affiliation(s)
- Christian Hoffmann
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117, Berlin, Germany
| | - Jakob Rentsch
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195, Berlin, Germany
| | - Taka A Tsunoyama
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST); Onna-son, Okinawa, 904-0495, Japan
| | - Akshita Chhabra
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117, Berlin, Germany
| | - Gerard Aguilar Perez
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117, Berlin, Germany
| | - Rajdeep Chowdhury
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Germany; Biostructural Imaging of Neurodegeneration (BIN) Center, Göttingen, Germany; Excellence Cluster Multiscale Bioimaging, 37073, Göttingen, Germany
| | - Franziska Trnka
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117, Berlin, Germany
| | - Aleksandr A Korobeinikov
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117, Berlin, Germany
| | - Ali H Shaib
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Germany; Biostructural Imaging of Neurodegeneration (BIN) Center, Göttingen, Germany; Excellence Cluster Multiscale Bioimaging, 37073, Göttingen, Germany
| | - Marcelo Ganzella
- Department of Neurobiology, Max Planck Institute for Multidisciplinary Sciences, 37077, Göttingen, Germany
| | - Gregory Giannone
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, UMR 5297, F-33000, Bordeaux, France
| | - Silvio O Rizzoli
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Germany; Biostructural Imaging of Neurodegeneration (BIN) Center, Göttingen, Germany; Excellence Cluster Multiscale Bioimaging, 37073, Göttingen, Germany
| | - Akihiro Kusumi
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST); Onna-son, Okinawa, 904-0495, Japan
| | - Helge Ewers
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195, Berlin, Germany
| | - Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117, Berlin, Germany.
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13
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Toledo PL, Gianotti AR, Vazquez DS, Ermácora MR. Protein nanocondensates: the next frontier. Biophys Rev 2023; 15:515-530. [PMID: 37681092 PMCID: PMC10480383 DOI: 10.1007/s12551-023-01105-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 07/21/2023] [Indexed: 09/09/2023] Open
Abstract
Over the past decade, myriads of studies have highlighted the central role of protein condensation in subcellular compartmentalization and spatiotemporal organization of biological processes. Conceptually, protein condensation stands at the highest level in protein structure hierarchy, accounting for the assembly of bodies ranging from thousands to billions of molecules and for densities ranging from dense liquids to solid materials. In size, protein condensates range from nanocondensates of hundreds of nanometers (mesoscopic clusters) to phase-separated micron-sized condensates. In this review, we focus on protein nanocondensation, a process that can occur in subsaturated solutions and can nucleate dense liquid phases, crystals, amorphous aggregates, and fibers. We discuss the nanocondensation of proteins in the light of general physical principles and examine the biophysical properties of several outstanding examples of nanocondensation. We conclude that protein nanocondensation cannot be fully explained by the conceptual framework of micron-scale biomolecular condensation. The evolution of nanocondensates through changes in density and order is currently under intense investigation, and this should lead to the development of a general theoretical framework, capable of encompassing the full range of sizes and densities found in protein condensates.
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Affiliation(s)
- Pamela L. Toledo
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, 1876, Bernal, Buenos Aires, Argentina
- Grupo de Biología Estructural y Biotecnología, IMBICE, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Alejo R. Gianotti
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, 1876, Bernal, Buenos Aires, Argentina
- Grupo de Biología Estructural y Biotecnología, IMBICE, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Diego S. Vazquez
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, 1876, Bernal, Buenos Aires, Argentina
- Grupo de Biología Estructural y Biotecnología, IMBICE, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Mario R. Ermácora
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, 1876, Bernal, Buenos Aires, Argentina
- Grupo de Biología Estructural y Biotecnología, IMBICE, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
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14
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Guo X, Zhu K, Zhu X, Zhao W, Miao Y. Two-dimensional molecular condensation in cell signaling and mechanosensing. Acta Biochim Biophys Sin (Shanghai) 2023; 55:1064-1074. [PMID: 37475548 PMCID: PMC10423693 DOI: 10.3724/abbs.2023132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 05/21/2023] [Indexed: 07/22/2023] Open
Abstract
Membraneless organelles (MLO) regulate diverse biological processes in a spatiotemporally controlled manner spanning from inside to outside of the cells. The plasma membrane (PM) at the cell surface serves as a central platform for forming multi-component signaling hubs that sense mechanical and chemical cues during physiological and pathological conditions. During signal transduction, the assembly and formation of membrane-bound MLO are dynamically tunable depending on the physicochemical properties of the surrounding environment and partitioning biomolecules. Biomechanical properties of MLO-associated membrane structures can control the microenvironment for biomolecular interactions and assembly. Lipid-protein complex interactions determine the catalytic region's assembly pattern and assembly rate and, thereby, the amplitude of activities. In this review, we will focus on how cell surface microenvironments, including membrane curvature, surface topology and tension, lipid-phase separation, and adhesion force, guide the assembly of PM-associated MLO for cell signal transductions.
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Affiliation(s)
- Xiangfu Guo
- School of ChemistryChemical Engineering and BiotechnologyNanyang Technological UniversitySingapore637457Singapore
| | - Kexin Zhu
- School of Biological SciencesNanyang Technological UniversitySingapore637551Singapore
| | - Xinlu Zhu
- School of Biological SciencesNanyang Technological UniversitySingapore637551Singapore
| | - Wenting Zhao
- School of ChemistryChemical Engineering and BiotechnologyNanyang Technological UniversitySingapore637457Singapore
- Institute for Digital Molecular Analytics and ScienceNanyang Technological UniversitySingapore636921Singapore
| | - Yansong Miao
- School of Biological SciencesNanyang Technological UniversitySingapore637551Singapore
- Institute for Digital Molecular Analytics and ScienceNanyang Technological UniversitySingapore636921Singapore
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15
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Hurtle BT, Xie L, Donnelly CJ. Disrupting pathologic phase transitions in neurodegeneration. J Clin Invest 2023; 133:e168549. [PMID: 37395272 DOI: 10.1172/jci168549] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2023] Open
Abstract
Solid-like protein deposits found in aged and diseased human brains have revealed a relationship between insoluble protein accumulations and the resulting deficits in neurologic function. Clinically diverse neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, frontotemporal lobar degeneration, and amyotrophic lateral sclerosis, exhibit unique and disease-specific biochemical protein signatures and abnormal protein depositions that often correlate with disease pathogenesis. Recent evidence indicates that many pathologic proteins assemble into liquid-like protein phases through the highly coordinated process of liquid-liquid phase separation. Over the last decade, biomolecular phase transitions have emerged as a fundamental mechanism of cellular organization. Liquid-like condensates organize functionally related biomolecules within the cell, and many neuropathology-associated proteins reside within these dynamic structures. Thus, examining biomolecular phase transitions enhances our understanding of the molecular mechanisms mediating toxicity across diverse neurodegenerative diseases. This Review explores the known mechanisms contributing to aberrant protein phase transitions in neurodegenerative diseases, focusing on tau and TDP-43 proteinopathies and outlining potential therapeutic strategies to regulate these pathologic events.
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Affiliation(s)
- Bryan T Hurtle
- Center for Neuroscience at the University of Pittsburgh Graduate Program
- Medical Scientist Training Program, University of Pittsburgh; and
- LiveLikeLou Center for ALS Research at the University of Pittsburgh Brain Institute; Pittsburgh, Pennsylvania, USA
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Longxin Xie
- LiveLikeLou Center for ALS Research at the University of Pittsburgh Brain Institute; Pittsburgh, Pennsylvania, USA
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- School of Medicine, Tsinghua University, Beijing, China
| | - Christopher J Donnelly
- Center for Neuroscience at the University of Pittsburgh Graduate Program
- Medical Scientist Training Program, University of Pittsburgh; and
- LiveLikeLou Center for ALS Research at the University of Pittsburgh Brain Institute; Pittsburgh, Pennsylvania, USA
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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16
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Sansevrino R, Hoffmann C, Milovanovic D. Condensate biology of synaptic vesicle clusters. Trends Neurosci 2023; 46:293-306. [PMID: 36725404 DOI: 10.1016/j.tins.2023.01.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 12/20/2022] [Accepted: 01/10/2023] [Indexed: 01/31/2023]
Abstract
Neuronal communication crucially relies on exocytosis of neurotransmitters from synaptic vesicles (SVs) which are clustered at synapses. To ensure reliable neurotransmitter release, synapses need to maintain an adequate pool of SVs at all times. Decades of research have established that SVs are clustered by synapsin 1, an abundant SV-associated phosphoprotein. The classical view postulates that SVs are crosslinked in a scaffold of protein-protein interactions between synapsins and their binding partners. Recent studies have shown that synapsins cluster SVs via liquid-liquid phase separation (LLPS), thus providing a new framework for the organization of the synapse. We discuss the evidence for phase separation of SVs, emphasizing emerging questions related to its regulation, specificity, and reversibility.
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Affiliation(s)
- Roberto Sansevrino
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Christian Hoffmann
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany.
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17
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Rothman JS, Borges-Merjane C, Holderith N, Jonas P, Silver RA. Validation of a stereological method for estimating particle size and density from 2D projections with high accuracy. PLoS One 2023; 18:e0277148. [PMID: 36930689 PMCID: PMC10022809 DOI: 10.1371/journal.pone.0277148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 03/02/2023] [Indexed: 03/18/2023] Open
Abstract
Stereological methods for estimating the 3D particle size and density from 2D projections are essential to many research fields. These methods are, however, prone to errors arising from undetected particle profiles due to sectioning and limited resolution, known as 'lost caps'. A potential solution developed by Keiding, Jensen, and Ranek in 1972, which we refer to as the Keiding model, accounts for lost caps by quantifying the smallest detectable profile in terms of its limiting 'cap angle' (ϕ), a size-independent measure of a particle's distance from the section surface. However, this simple solution has not been widely adopted nor tested. Rather, model-independent design-based stereological methods, which do not explicitly account for lost caps, have come to the fore. Here, we provide the first experimental validation of the Keiding model by comparing the size and density of particles estimated from 2D projections with direct measurement from 3D EM reconstructions of the same tissue. We applied the Keiding model to estimate the size and density of somata, nuclei and vesicles in the cerebellum of mice and rats, where high packing density can be problematic for design-based methods. Our analysis reveals a Gaussian distribution for ϕ rather than a single value. Nevertheless, curve fits of the Keiding model to the 2D diameter distribution accurately estimate the mean ϕ and 3D diameter distribution. While systematic testing using simulations revealed an upper limit to determining ϕ, our analysis shows that estimated ϕ can be used to determine the 3D particle density from the 2D density under a wide range of conditions, and this method is potentially more accurate than minimum-size-based lost-cap corrections and disector methods. Our results show the Keiding model provides an efficient means of accurately estimating the size and density of particles from 2D projections even under conditions of a high density.
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Affiliation(s)
- Jason Seth Rothman
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | | | - Noemi Holderith
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest, Hungary
| | - Peter Jonas
- Cellular Neuroscience, Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - R. Angus Silver
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
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18
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Wang X, Sela-Donenfeld D, Wang Y. Axonal and presynaptic FMRP: Localization, signal, and functional implications. Hear Res 2023; 430:108720. [PMID: 36809742 PMCID: PMC9998378 DOI: 10.1016/j.heares.2023.108720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 01/22/2023] [Accepted: 02/09/2023] [Indexed: 02/12/2023]
Abstract
Fragile X mental retardation protein (FMRP) binds a selected set of mRNAs and proteins to guide neural circuit assembly and regulate synaptic plasticity. Loss of FMRP is responsible for Fragile X syndrome, a neuropsychiatric disorder characterized with auditory processing problems and social difficulty. FMRP actions in synaptic formation, maturation, and plasticity are site-specific among the four compartments of a synapse: presynaptic and postsynaptic neurons, astrocytes, and extracellular matrix. This review summarizes advancements in understanding FMRP localization, signals, and functional roles in axons and presynaptic terminals.
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Affiliation(s)
- Xiaoyu Wang
- Division of Histology & Embryology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Medical College, Jinan University, Guangzhou 510632, China
| | - Dalit Sela-Donenfeld
- Koret School of Veterinary Medicine, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | - Yuan Wang
- Department of Biomedical Sciences, Program in Neuroscience, Florida State University College of Medicine, Tallahassee, FL 32306, USA.
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19
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Synaptic vesicle proteins and ATG9A self-organize in distinct vesicle phases within synapsin condensates. Nat Commun 2023; 14:455. [PMID: 36709207 PMCID: PMC9884207 DOI: 10.1038/s41467-023-36081-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Accepted: 01/16/2023] [Indexed: 01/30/2023] Open
Abstract
Ectopic expression in fibroblasts of synapsin 1 and synaptophysin is sufficient to generate condensates of vesicles highly reminiscent of synaptic vesicle (SV) clusters and with liquid-like properties. Here we show that unlike synaptophysin, other major integral SV membrane proteins fail to form condensates with synapsin, but co-assemble into the clusters formed by synaptophysin and synapsin in this ectopic expression system. Another vesicle membrane protein, ATG9A, undergoes activity-dependent exo-endocytosis at synapses, raising questions about the relation of ATG9A traffic to the traffic of SVs. We find that both in fibroblasts and in nerve terminals ATG9A does not co-assemble into synaptophysin-positive vesicle condensates but localizes on a distinct class of vesicles that also assembles with synapsin but into a distinct phase. Our findings suggest that ATG9A undergoes differential sorting relative to SV proteins and also point to a dual role of synapsin in controlling clustering at synapses of SVs and ATG9A vesicles.
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20
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Liquid-liquid Phase Separation of α-Synuclein: A New Mechanistic Insight for α-Synuclein Aggregation Associated with Parkinson's Disease Pathogenesis. J Mol Biol 2023; 435:167713. [PMID: 35787838 DOI: 10.1016/j.jmb.2022.167713] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 06/25/2022] [Accepted: 06/27/2022] [Indexed: 02/04/2023]
Abstract
Aberrant aggregation of the misfolded presynaptic protein, α-Synuclein (α-Syn) into Lewy body (LB) and Lewy neuritis (LN) is a major pathological hallmark of Parkinson's disease (PD) and other synucleinopathies. Numerous studies have suggested that prefibrillar and fibrillar species of the misfolded α-Syn aggregates are responsible for cell death in PD pathogenesis. However, the precise molecular events during α-Syn aggregation, especially in the early stages, remain elusive. Emerging evidence has demonstrated that liquid-liquid phase separation (LLPS) of α-Syn occurs in the nucleation step of α-Syn aggregation, which offers an alternate non-canonical aggregation pathway in the crowded microenvironment. The liquid-like α-Syn droplets gradually undergo an irreversible liquid-to-solid phase transition into amyloid-like hydrogel entrapping oligomers and fibrils. This new mechanism of α-Syn LLPS and gel formation might represent the molecular basis of cellular toxicity associated with PD. This review aims to demonstrate the recent development of α-Syn LLPS, the underlying mechanism along with the microscopic events of aberrant phase transition. This review further discusses how several intrinsic and extrinsic factors regulate the thermodynamics and kinetics of α-Syn LLPS and co-LLPS with other proteins, which might explain the pathophysiology of α-Syn in various neurodegenerative diseases.
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21
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Wu X, Qiu H, Zhang M. Interactions between Membraneless Condensates and Membranous Organelles at the Presynapse: A Phase Separation View of Synaptic Vesicle Cycle. J Mol Biol 2023; 435:167629. [PMID: 35595170 DOI: 10.1016/j.jmb.2022.167629] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/03/2022] [Accepted: 05/04/2022] [Indexed: 02/04/2023]
Abstract
Action potential-induced neurotransmitter release in presynaptic boutons involves coordinated actions of a large list of proteins that are associated directly or indirectly with membrane structures including synaptic vesicles and plasma membranes. These proteins are often highly abundant in different synaptic bouton sub-compartments, and they rarely act alone. Instead, these proteins interact with each other forming intricate and distinct molecular complexes. Many of these complexes form condensed clusters on membrane surfaces. This review summarizes findings in recent years showing that many of presynaptic protein complex assemblies are formed via phase separation. These protein condensates extensively interact with lipid membranes via distinct modes, forming various mesoscale structures by different mode of organizations between membraneless condensates and membranous organelles. We discuss that such mesoscale interactions could have deep implications on mobilization, exocytosis, and retrieval of synaptic vesicles.
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Affiliation(s)
- Xiandeng Wu
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Hua Qiu
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingjie Zhang
- Greater Bay Biomedical Innocenter, Shenzhen Bay Laboratory, Shenzhen 518036, China; School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
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22
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Pyrpassopoulos S, Gicking AM, Zaniewski TM, Hancock WO, Ostap EM. KIF1A is kinetically tuned to be a superengaging motor under hindering loads. Proc Natl Acad Sci U S A 2023; 120:e2216903120. [PMID: 36598948 PMCID: PMC9926277 DOI: 10.1073/pnas.2216903120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 11/04/2022] [Indexed: 01/05/2023] Open
Abstract
KIF1A is a highly processive vesicle transport motor in the kinesin-3 family. Mutations in KIF1A lead to neurodegenerative diseases including hereditary spastic paraplegia. We applied optical tweezers to study the ability of KIF1A to generate and sustain force against hindering loads. We used both the three-bead assay, where force is oriented parallel to the microtubule, and the traditional single-bead assay, where force is directed along the radius of the bead, resulting in a vertical force component. The average force and attachment duration of KIF1A in the three-bead assay were substantially greater than those observed in the single-bead assay. Thus, vertical forces accelerate termination of force ramps of KIF1A. Average KIF1A termination forces were slightly lower than the kinesin-1 KIF5B, and the median attachment duration of KIF1A was >10-fold shorter than KIF5B under hindering loads. KIF1A rapidly reengages with microtubules after detachment, as observed previously. Strikingly, quantification enabled by the three-bead assay shows that reengagement largely occurs within 2 ms of detachment, indicating that KIF1A has a nearly 10-fold faster reengagement rate than KIF5B. We found that rapid microtubule reengagement is not due to KIF1A's positively charged loop-12; however, removal of charge from this loop diminished the unloaded run length at near physiological ionic strength. Both loop-12 and the microtubule nucleotide state have modulatory effects on reengagement under load, suggesting a role for the microtubule lattice in KIF1A reengagement. Our results reveal adaptations of KIF1A that lead to a model of superengaging transport under load.
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Affiliation(s)
- Serapion Pyrpassopoulos
- The Pennsylvania Muscle Institute, Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA19104
- Center for Engineering Mechanobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA19104
| | - Allison M. Gicking
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA16802
| | - Taylor M. Zaniewski
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA16802
- Department of Chemistry, Pennsylvania State University, University Park, PA16802
| | - William O. Hancock
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA16802
- Department of Chemistry, Pennsylvania State University, University Park, PA16802
| | - E. Michael Ostap
- The Pennsylvania Muscle Institute, Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA19104
- Center for Engineering Mechanobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA19104
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23
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Milovanovic D, Rizzoli SO. Editorial: Protein Phase Separation and Aggregation in (Patho)Physiology of Neurons. Front Physiol 2022; 13:959570. [PMID: 35860657 PMCID: PMC9289605 DOI: 10.3389/fphys.2022.959570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 06/13/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases, Berlin, Germany
- *Correspondence: Dragomir Milovanovic, ; Silvio O. Rizzoli,
| | - Silvio O. Rizzoli
- Institute of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
- *Correspondence: Dragomir Milovanovic, ; Silvio O. Rizzoli,
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24
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Brodin L, Milovanovic D, Rizzoli SO, Shupliakov O. α-Synuclein in the Synaptic Vesicle Liquid Phase: Active Player or Passive Bystander? Front Mol Biosci 2022; 9:891508. [PMID: 35664678 PMCID: PMC9159372 DOI: 10.3389/fmolb.2022.891508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/26/2022] [Indexed: 12/15/2022] Open
Abstract
The protein α-synuclein, which is well-known for its links to Parkinson’s Disease, is associated with synaptic vesicles (SVs) in nerve terminals. Despite intensive studies, its precise physiological function remains elusive. Accumulating evidence indicates that liquid-liquid phase separation takes part in the assembly and/or maintenance of different synaptic compartments. The current review discusses recent data suggesting α-synuclein as a component of the SV liquid phase. We also consider possible implications of these data for disease.
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Affiliation(s)
- Lennart Brodin
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- *Correspondence: Lennart Brodin, ; Oleg Shupliakov,
| | - Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Silvio O. Rizzoli
- Institute of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Institute of Translational Biomedicine, St. Petersburg University, St. Petersburg, Russia
- *Correspondence: Lennart Brodin, ; Oleg Shupliakov,
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25
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Kasatkina LA, Gumenyuk VP, Lisakovska OO, Trikash IO. Targeting hippocampal amyloidogenesis with SV2A protein modulator levetiracetam. Biochem Pharmacol 2022; 197:114927. [DOI: 10.1016/j.bcp.2022.114927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 01/12/2022] [Accepted: 01/13/2022] [Indexed: 11/24/2022]
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26
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do Amaral MJ, Freire MHO, Almeida MS, Pinheiro AS, Cordeiro Y. Phase separation of the mammalian prion protein: physiological and pathological perspectives. J Neurochem 2022. [PMID: 35149997 DOI: 10.1111/jnc.15586] [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: 10/08/2021] [Revised: 01/24/2022] [Accepted: 01/31/2022] [Indexed: 11/27/2022]
Abstract
Abnormal phase transitions have been implicated in the occurrence of proteinopathies. Disordered proteins with nucleic acid binding ability drive the formation of reversible micron-sized condensates capable of controlling nucleic acid processing/transport. This mechanism, achieved via liquid-liquid phase separation (LLPS), underlies the formation of long-studied membraneless organelles (e.g., nucleolus) and various transient condensates formed by driver proteins. The prion protein (PrP) is not a classical nucleic acid-binding protein. However, it binds nucleic acids with high affinity, undergoes nucleocytoplasmic shuttling, contains a long intrinsically disordered region rich in glycines and evenly spaced aromatic residues, among other biochemical/biophysical properties of bona fide drivers of phase transitions. Because of this, our group and others have characterized LLPS of recombinant PrP. In vitro phase separation of PrP is modulated by nucleic acid aptamers, and, depending on the aptamer conformation, the liquid droplets evolve to solid-like species. Herein we discuss recent studies and previous evidence supporting PrP phase transitions. We focus on the central role of LLPS related to PrP physiology and pathology, with a special emphasis on the interaction of PrP with different ligands, such as proteins and nucleic acids, which can play a role in prion disease pathogenesis. Finally, we comment on therapeutic strategies directed at the nonfunctional phase separation that could potentially tackle prion diseases or other protein misfolding disorders.
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Affiliation(s)
- Mariana J do Amaral
- Faculty of Pharmacy, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | | | | | - Anderson S Pinheiro
- Department of Biochemistry, Institute of Chemistry, Rio de Janeiro, RJ, Brazil
| | - Yraima Cordeiro
- Faculty of Pharmacy, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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27
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Li W, Jiang C, Zhang E. Advances in the phase separation-organized membraneless organelles in cells: a narrative review. Transl Cancer Res 2022; 10:4929-4946. [PMID: 35116344 PMCID: PMC8797891 DOI: 10.21037/tcr-21-1111] [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: 06/28/2021] [Accepted: 10/29/2021] [Indexed: 11/26/2022]
Abstract
Membraneless organelles (MLOs) are micro-compartments that lack delimiting membranes, concentrating several macro-molecules with a high local concentration in eukaryotic cells. Recent studies have shown that MLOs have pivotal roles in multiple biological processes, including gene transcription, RNA metabolism, translation, protein modification, and signal transduction. These biological processes in cells have essential functions in many diseases, such as cancer, neurodegenerative diseases, and virus-related diseases. The liquid-liquid phase separation (LLPS) microenvironment within cells is thought to be the driving force for initiating the formation of micro-compartments with a liquid-like property, becoming an important organizing principle for MLOs to mediate organism responses. In this review, we comprehensively elucidated the formation of these MLOs and the relationship between biological functions and associated diseases. The mechanisms underlying the influence of protein concentration and valency on phase separation in cells are also discussed. MLOs undergoing the LLPS process have diverse functions, including stimulation of some adaptive and reversible responses to alter the transcriptional or translational processes, regulation of the concentrations of biomolecules in living cells, and maintenance of cell morphogenesis. Finally, we highlight that the development of this field could pave the way for developing novel therapeutic strategies for the treatment of LLPS-related diseases based on the understanding of phase separation in the coming years.
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Affiliation(s)
- Weihan Li
- Department of Immunology, School of Medicine, Nantong University, Nantong, China
| | - Chenwei Jiang
- Department of Immunology, School of Medicine, Nantong University, Nantong, China
| | - Erhao Zhang
- Department of Immunology, School of Medicine, Nantong University, Nantong, China.,Laboratory of Medical Science, School of Medicine, Nantong University, Nantong, China
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28
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Abstract
Fundamental discoveries have shaped our molecular understanding of presynaptic processes, such as neurotransmitter release, active zone organization and mechanisms of synaptic vesicle (SV) recycling. However, certain regulatory steps still remain incompletely understood. Protein liquid-liquid phase separation (LLPS) and its role in SV clustering and active zone regulation now introduce a new perception of how the presynapse and its different compartments are organized. This article highlights the newly emerging concept of LLPS at the synapse, providing a systematic overview on LLPS tendencies of over 500 presynaptic proteins, spotlighting individual proteins and discussing recent progress in the field. Newly discovered LLPS systems like ELKS/liprin-alpha and Eps15/FCho are put into context, and further LLPS candidate proteins, including epsin1, dynamin, synaptojanin, complexin and rabphilin-3A, are highlighted.
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Affiliation(s)
- Janin Lautenschläger
- Department of Clinical Neurosciences, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
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29
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Clayton EL, Bonnycastle K, Isaacs AM, Cousin MA, Schorge S. A novel synaptopathy-defective synaptic vesicle protein trafficking in the mutant CHMP2B mouse model of frontotemporal dementia. J Neurochem 2022; 160:412-425. [PMID: 34855215 DOI: 10.1111/jnc.15551] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 11/10/2021] [Accepted: 11/18/2021] [Indexed: 12/13/2022]
Abstract
Mutations in the ESCRT-III subunit CHMP2B cause frontotemporal dementia (FTD) and lead to impaired endolysosomal trafficking and lysosomal storage pathology in neurons. We investigated the effect of mutant CHMP2B on synaptic pathology, as ESCRT function was recently implicated in the degradation of synaptic vesicle (SV) proteins. We report here that expression of C-terminally truncated mutant CHMP2B results in a novel synaptopathy. This unique synaptic pathology is characterised by selective retention of presynaptic SV trafficking proteins in aged mutant CHMP2B transgenic mice, despite significant loss of postsynaptic proteins. Furthermore, ultrastructural analysis of primary cortical cultures from transgenic CHMP2B mice revealed a significant increase in the number of presynaptic endosomes, while neurons expressing mutant CHMP2B display defective SV recycling and alterations to functional SV pools. Therefore, we reveal how mutations in CHMP2B affect specific presynaptic proteins and SV recycling, identifying CHMP2B FTD as a novel synaptopathy. This novel synaptopathic mechanism of impaired SV physiology may be a key early event in multiple forms of FTD, since proteins that mediate the most common genetic forms of FTD all localise at the presynapse.
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Affiliation(s)
- Emma L Clayton
- Department of Pharmacology, UCL School of Pharmacy, London, UK
- Currently at UK Dementia Research Institute at King's College London, London, UK
| | - Katherine Bonnycastle
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, Scotland
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, Scotland
| | - Adrian M Isaacs
- UK Dementia Research Institute at UCL, London, UK
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, Scotland
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, Scotland
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30
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Lin YH, Wu H, Jia B, Zhang M, Chan HS. Assembly of model postsynaptic densities involves interactions auxiliary to stoichiometric binding. Biophys J 2022; 121:157-171. [PMID: 34637756 PMCID: PMC8758407 DOI: 10.1016/j.bpj.2021.10.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 09/29/2021] [Accepted: 10/06/2021] [Indexed: 01/07/2023] Open
Abstract
The assembly of functional biomolecular condensates often involves liquid-liquid phase separation (LLPS) of proteins with multiple modular domains, which can be folded or conformationally disordered to various degrees. To understand the LLPS-driving domain-domain interactions, a fundamental question is how readily the interactions in the condensed phase can be inferred from interdomain interactions in dilute solutions. In particular, are the interactions leading to LLPS exclusively those underlying the formation of discrete interdomain complexes in homogeneous solutions? We address this question by developing a mean-field LLPS theory of two stoichiometrically constrained solute species. The theory is applied to the neuronal proteins SynGAP and PSD-95, whose complex coacervate serves as a rudimentary model for neuronal postsynaptic densities (PSDs). The predicted phase behaviors are compared with experiments. Previously, a three SynGAP/two PSD-95 ratio was determined for SynGAP/PSD-95 complexes in dilute solutions. However, when this 3:2 stoichiometry is uniformly imposed in our theory encompassing both dilute and condensed phases, the tie-line pattern of the predicted SynGAP/PSD-95 phase diagram differs drastically from that obtained experimentally. In contrast, theories embodying alternate scenarios postulating auxiliary SynGAP-PSD-95 as well as SynGAP-SynGAP and PSD-95-PSD-95 interactions, in addition to those responsible for stoichiometric SynGAP/PSD-95 complexes, produce tie-line patterns consistent with experiment. Hence, our combined theoretical-experimental analysis indicates that weaker interactions or higher-order complexes beyond the 3:2 stoichiometry, but not yet documented, are involved in the formation of SynGAP/PSD-95 condensates, imploring future efforts to ascertain the nature of these auxiliary interactions in PSD-like LLPS and underscoring a likely general synergy between stoichiometric, structurally specific binding and stochastic, multivalent "fuzzy" interactions in the assembly of functional biomolecular condensates.
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Affiliation(s)
- Yi-Hsuan Lin
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada,Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Haowei Wu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Bowen Jia
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China,School of Life Sciences, Southern University of Science and Technology, Shenzhen, China,Corresponding author
| | - Hue Sun Chan
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada,Corresponding author
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31
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Moschetta M, Ravasenga T, De Fusco A, Maragliano L, Aprile D, Orlando M, Sacchetti S, Casagrande S, Lignani G, Fassio A, Baldelli P, Benfenati F. Ca 2+ binding to synapsin I regulates resting Ca 2+ and recovery from synaptic depression in nerve terminals. Cell Mol Life Sci 2022; 79:600. [PMID: 36409372 PMCID: PMC9678998 DOI: 10.1007/s00018-022-04631-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/23/2022] [Accepted: 11/13/2022] [Indexed: 11/22/2022]
Abstract
Synapsin I (SynI) is a synaptic vesicle (SV)-associated phosphoprotein that modulates neurotransmission by controlling SV trafficking. The SynI C-domain contains a highly conserved ATP binding site mediating SynI oligomerization and SV clustering and an adjacent main Ca2+ binding site, whose physiological role is unexplored. Molecular dynamics simulations revealed that the E373K point mutation irreversibly deletes Ca2+ binding to SynI, still allowing ATP binding, but inducing a destabilization of the SynI oligomerization interface. Here, we analyzed the effects of this mutation on neurotransmitter release and short-term plasticity in excitatory and inhibitory synapses from primary hippocampal neurons. Patch-clamp recordings showed an increase in the frequency of miniature excitatory postsynaptic currents (EPSCs) that was totally occluded by exogenous Ca2+ chelators and associated with a constitutive increase in resting terminal Ca2+ concentrations. Evoked EPSC amplitude was also reduced, due to a decreased readily releasable pool (RRP) size. Moreover, in both excitatory and inhibitory synapses, we observed a marked impaired recovery from synaptic depression, associated with impaired RRP refilling and depletion of the recycling pool of SVs. Our study identifies SynI as a novel Ca2+ buffer in excitatory terminals. Blocking Ca2+ binding to SynI results in higher constitutive Ca2+ levels that increase the probability of spontaneous release and disperse SVs. This causes a decreased size of the RRP and an impaired recovery from depression due to the failure of SV reclustering after sustained high-frequency stimulation. The results indicate a physiological role of Ca2+ binding to SynI in the regulation of SV clustering and trafficking in nerve terminals.
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Affiliation(s)
- Matteo Moschetta
- Center for Synaptic Neuroscience and Technology, Istituto Italiano Di Tecnologia, Largo Rosanna Benzi 10, 16132 Genoa, Italy ,Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genoa, Italy
| | - Tiziana Ravasenga
- Center for Synaptic Neuroscience and Technology, Istituto Italiano Di Tecnologia, Largo Rosanna Benzi 10, 16132 Genoa, Italy ,IRCCS, Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genoa, Italy
| | - Antonio De Fusco
- Center for Synaptic Neuroscience and Technology, Istituto Italiano Di Tecnologia, Largo Rosanna Benzi 10, 16132 Genoa, Italy ,Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genoa, Italy
| | - Luca Maragliano
- Center for Synaptic Neuroscience and Technology, Istituto Italiano Di Tecnologia, Largo Rosanna Benzi 10, 16132 Genoa, Italy ,Department of Life and Environmental Sciences, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy
| | - Davide Aprile
- Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genoa, Italy ,Present Address: High-Definition Disease Modelling Lab, Campus IFOM-IEO, Milan, Italy
| | - Marta Orlando
- Center for Synaptic Neuroscience and Technology, Istituto Italiano Di Tecnologia, Largo Rosanna Benzi 10, 16132 Genoa, Italy ,Present Address: Charitè Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität Zu Berlin, Berlin Institute of Health, NeuroCure Cluster of Excellence, Berlin, Germany
| | - Silvio Sacchetti
- Center for Synaptic Neuroscience and Technology, Istituto Italiano Di Tecnologia, Largo Rosanna Benzi 10, 16132 Genoa, Italy
| | - Silvia Casagrande
- Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genoa, Italy
| | - Gabriele Lignani
- Center for Synaptic Neuroscience and Technology, Istituto Italiano Di Tecnologia, Largo Rosanna Benzi 10, 16132 Genoa, Italy ,Present Address: Queens Square Institute of Neurology, University College London, London, UK
| | - Anna Fassio
- Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genoa, Italy ,IRCCS, Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genoa, Italy
| | - Pietro Baldelli
- Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genoa, Italy ,IRCCS, Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genoa, Italy
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology, Istituto Italiano Di Tecnologia, Largo Rosanna Benzi 10, 16132 Genoa, Italy ,IRCCS, Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genoa, Italy
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32
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Fouke KE, Wegman ME, Weber SA, Brady EB, Román-Vendrell C, Morgan JR. Synuclein Regulates Synaptic Vesicle Clustering and Docking at a Vertebrate Synapse. Front Cell Dev Biol 2021; 9:774650. [PMID: 34901020 PMCID: PMC8660973 DOI: 10.3389/fcell.2021.774650] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 11/10/2021] [Indexed: 11/17/2022] Open
Abstract
Neurotransmission relies critically on the exocytotic release of neurotransmitters from small synaptic vesicles (SVs) at the active zone. Therefore, it is essential for neurons to maintain an adequate pool of SVs clustered at synapses in order to sustain efficient neurotransmission. It is well established that the phosphoprotein synapsin 1 regulates SV clustering at synapses. Here, we demonstrate that synuclein, another SV-associated protein and synapsin binding partner, also modulates SV clustering at a vertebrate synapse. When acutely introduced to unstimulated lamprey reticulospinal synapses, a pan-synuclein antibody raised against the N-terminal domain of α-synuclein induced a significant loss of SVs at the synapse. Both docked SVs and the distal reserve pool of SVs were depleted, resulting in a loss of total membrane at synapses. In contrast, antibodies against two other abundant SV-associated proteins, synaptic vesicle glycoprotein 2 (SV2) and vesicle-associated membrane protein (VAMP/synaptobrevin), had no effect on the size or distribution of SV clusters. Synuclein perturbation caused a dose-dependent reduction in the number of SVs at synapses. Interestingly, the large SV clusters appeared to disperse into smaller SV clusters, as well as individual SVs. Thus, synuclein regulates clustering of SVs at resting synapses, as well as docking of SVs at the active zone. These findings reveal new roles for synuclein at the synapse and provide critical insights into diseases associated with α-synuclein dysfunction, such as Parkinson’s disease.
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Affiliation(s)
- Kaitlyn E Fouke
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States.,Department of Neurobiology, Duke University, Durham, NC, United States
| | - M Elizabeth Wegman
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | - Sarah A Weber
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States.,Biological Sciences Collegiate Division, The University of Chicago, Chicago, IL, United States
| | - Emily B Brady
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | - Cristina Román-Vendrell
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | - Jennifer R Morgan
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
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33
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Kusumaatmaja H, May AI, Knorr RL. Intracellular wetting mediates contacts between liquid compartments and membrane-bound organelles. J Cell Biol 2021; 220:212595. [PMID: 34427635 PMCID: PMC8404468 DOI: 10.1083/jcb.202103175] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 07/14/2021] [Accepted: 08/05/2021] [Indexed: 12/29/2022] Open
Abstract
Protein-rich droplets, such as stress granules, P-bodies, and the nucleolus, perform diverse and specialized cellular functions. Recent evidence has shown the droplets, which are also known as biomolecular condensates or membrane-less compartments, form by phase separation. Many droplets also contact membrane-bound organelles, thereby functioning in development, intracellular degradation, and organization. These underappreciated interactions have major implications for our fundamental understanding of cells. Starting with a brief introduction to wetting phenomena, we summarize recent progress in the emerging field of droplet-membrane contact. We describe the physical mechanism of droplet-membrane interactions, discuss how these interactions remodel droplets and membranes, and introduce "membrane scaffolding" by liquids as a novel reshaping mechanism, thereby demonstrating that droplet-membrane interactions are elastic wetting phenomena. "Membrane-less" and "membrane-bound" condensates likely represent distinct wetting states that together link phase separation with mechanosensitivity and explain key structures observed during embryogenesis, during autophagy, and at synapses. We therefore contend that droplet wetting on membranes provides a robust and intricate means of intracellular organization.
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Affiliation(s)
| | - Alexander I May
- Tokyo Tech World Research Hub Initiative, Institute of Innovative Research, Tokyo Institute of Technology, Kanagawa, Japan.,Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Roland L Knorr
- Graduate School and Faculty of Medicine, University of Tokyo, Tokyo, Japan.,Integrative Research Institute for the Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany
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34
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Sertel SM, Blumenstein W, Mandad S, Shomroni O, Salinas G, Rizzoli SO. Differences in synaptic vesicle pool behavior between male and female hippocampal cultured neurons. Sci Rep 2021; 11:17374. [PMID: 34462487 PMCID: PMC8405817 DOI: 10.1038/s41598-021-96846-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 08/17/2021] [Indexed: 12/15/2022] Open
Abstract
A strong focus on sex-related differences has arisen recently in neurobiology, but most investigations focus on brain function in vivo, ignoring common experimental models like cultured neurons. A few studies have addressed morphological differences between male and female neurons in culture, but very few works focused on functional aspects, and especially on presynaptic function. To fill this gap, we studied here functional parameters of synaptic vesicle recycling in hippocampal cultures from male and female rats, which are a standard model system for many laboratories. We found that, although the total vesicle pools are similar, the recycling pool of male synapses was larger, and was more frequently used. This was in line with the observation that the male synapses engaged in stronger local translation. Nevertheless, the general network activity of the neurons was similar, and only small differences could be found when stimulating the cultures. We also found only limited differences in several other assays. We conclude that, albeit these cultures are similar in behavior, future studies of synapse behavior in culture should take the sex of the animals into account.
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Affiliation(s)
- Sinem M Sertel
- Institute for Neuro- and Sensory Physiology, University Medical Center Göttingen, 37075, Göttingen, Germany. .,Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37073, Göttingen, Germany.
| | - Wiebke Blumenstein
- Institute for Neuro- and Sensory Physiology, University Medical Center Göttingen, 37075, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37073, Göttingen, Germany
| | - Sunit Mandad
- Institute for Neuro- and Sensory Physiology, University Medical Center Göttingen, 37075, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37073, Göttingen, Germany
| | - Orr Shomroni
- NGS-Integrative Genomics Core Unit Göttingen (NIG), Institute of Human Genetics, University Medical Center Göttingen, 37077, Göttingen, Germany
| | - Gabriela Salinas
- NGS-Integrative Genomics Core Unit Göttingen (NIG), Institute of Human Genetics, University Medical Center Göttingen, 37077, Göttingen, Germany
| | - Silvio O Rizzoli
- Institute for Neuro- and Sensory Physiology, University Medical Center Göttingen, 37075, Göttingen, Germany. .,Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37073, Göttingen, Germany.
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Longhena F, Faustini G, Brembati V, Pizzi M, Benfenati F, Bellucci A. An updated reappraisal of synapsins: structure, function and role in neurological and psychiatric disorders. Neurosci Biobehav Rev 2021; 130:33-60. [PMID: 34407457 DOI: 10.1016/j.neubiorev.2021.08.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 07/29/2021] [Accepted: 08/09/2021] [Indexed: 01/02/2023]
Abstract
Synapsins (Syns) are phosphoproteins strongly involved in neuronal development and neurotransmitter release. Three distinct genes SYN1, SYN2 and SYN3, with elevated evolutionary conservation, have been described to encode for Synapsin I, Synapsin II and Synapsin III, respectively. Syns display a series of common features, but also exhibit distinctive localization, expression pattern, post-translational modifications (PTM). These characteristics enable their interaction with other synaptic proteins, membranes and cytoskeletal components, which is essential for the proper execution of their multiple functions in neuronal cells. These include the control of synapse formation and growth, neuron maturation and renewal, as well as synaptic vesicle mobilization, docking, fusion, recycling. Perturbations in the balanced expression of Syns, alterations of their PTM, mutations and polymorphisms of their encoding genes induce severe dysregulations in brain networks functions leading to the onset of psychiatric or neurological disorders. This review presents what we have learned since the discovery of Syn I in 1977, providing the state of the art on Syns structure, function, physiology and involvement in central nervous system disorders.
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Affiliation(s)
- Francesca Longhena
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
| | - Gaia Faustini
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
| | - Viviana Brembati
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
| | - Marina Pizzi
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
| | - Fabio Benfenati
- Italian Institute of Technology, Via Morego 30, Genova, Italy; IRCSS Policlinico San Martino Hospital, Largo Rosanna Benzi 10, 16132, Genova, Italy.
| | - Arianna Bellucci
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy; Laboratory for Preventive and Personalized Medicine, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
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36
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Jamecna D, Antonny B. Intrinsically disordered protein regions at membrane contact sites. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:159020. [PMID: 34352388 DOI: 10.1016/j.bbalip.2021.159020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/30/2021] [Accepted: 07/01/2021] [Indexed: 12/14/2022]
Abstract
Membrane contact sites (MCS) are regions of close apposition between membrane-bound organelles. Proteins that occupy MCS display various domain organisation. Among them, lipid transfer proteins (LTPs) frequently contain both structured domains as well as regions of intrinsic disorder. In this review, we discuss the various roles of intrinsically disordered protein regions (IDPRs) in LTPs as well as in other proteins that are associated with organelle contact sites. We distinguish the following functions: (i) to act as flexible tethers between two membranes; (ii) to act as entropic barriers to prevent protein crowding and regulate membrane tethering geometry; (iii) to define the action range of catalytic domains. These functions are added to other functions of IDPRs in membrane environments, such as mediating protein-protein and protein-membrane interactions. We suggest that the overall efficiency and fidelity of contact sites might require fine coordination between all these IDPR activities.
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Affiliation(s)
- Denisa Jamecna
- Université Côte d'Azur et CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne, France; Biochemistry Center (BZH), Heidelberg, Germany
| | - Bruno Antonny
- Université Côte d'Azur et CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne, France.
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37
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Oliveira LMA, Gasser T, Edwards R, Zweckstetter M, Melki R, Stefanis L, Lashuel HA, Sulzer D, Vekrellis K, Halliday GM, Tomlinson JJ, Schlossmacher M, Jensen PH, Schulze-Hentrich J, Riess O, Hirst WD, El-Agnaf O, Mollenhauer B, Lansbury P, Outeiro TF. Alpha-synuclein research: defining strategic moves in the battle against Parkinson's disease. NPJ Parkinsons Dis 2021; 7:65. [PMID: 34312398 PMCID: PMC8313662 DOI: 10.1038/s41531-021-00203-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 05/14/2021] [Indexed: 12/13/2022] Open
Abstract
With the advent of the genetic era in Parkinson's disease (PD) research in 1997, α-synuclein was identified as an important player in a complex neurodegenerative disease that affects >10 million people worldwide. PD has been estimated to have an economic impact of $51.9 billion in the US alone. Since the initial association with PD, hundreds of researchers have contributed to elucidating the functions of α-synuclein in normal and pathological states, and these remain critical areas for continued research. With this position paper the authors strive to achieve two goals: first, to succinctly summarize the critical features that define α-synuclein's varied roles, as they are known today; and second, to identify the most pressing knowledge gaps and delineate a multipronged strategy for future research with the goal of enabling therapies to stop or slow disease progression in PD.
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Affiliation(s)
- Luis M A Oliveira
- The Michael J. Fox Foundation for Parkinson's Research, New York, NY, USA.
| | - Thomas Gasser
- Department of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Robert Edwards
- Departments of Neurology and Physiology, UCSF School of Medicine, San Francisco, CA, USA
| | - Markus Zweckstetter
- German Center for Neurodegenerative Diseases (DZNE), Göttingen, Germany
- Department for NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Ronald Melki
- Institut François Jacob, MIRCen, CEA and Laboratory of Neurodegenerative Diseases, CNRS, Fontenay-aux-Roses, France
| | - Leonidas Stefanis
- Biomedical Research Foundation of the Academy of Athens, Athens, Greece
- First Department of Neurology, Medical School of the National and Kapodistrian University of Athens, Athens, Greece
| | - Hilal A Lashuel
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Faculty of Life Sciences, EPFL, Lausanne, Switzerland
| | - David Sulzer
- Department of Psychiatry, Neurology, Molecular Pharmacology and Therapeutics, Columbia University, New York, NY, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA
| | - Kostas Vekrellis
- Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Glenda M Halliday
- University of Sydney, Brain and Mind Centre and Faculty of Medicine and Health, School of Medical Sciences, Sydney, NSW, Australia
| | - Julianna J Tomlinson
- Neuroscience Program, The Ottawa Hospital, Ottawa, ON, Canada
- University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada
| | - Michael Schlossmacher
- Neuroscience Program, The Ottawa Hospital, Ottawa, ON, Canada
- University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada
- Division of Neurology, The Ottawa Hospital, Ottawa, ON, Canada
| | - Poul Henning Jensen
- Aarhus University, Department of Biomedicine & DANDRITE, Danish Research Institute of Translational Neuroscience, Aarhus, Denmark
| | - Julia Schulze-Hentrich
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Olaf Riess
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Warren D Hirst
- Neurodegenerative Diseases Research Unit, Biogen, Cambridge, MA, USA
| | - Omar El-Agnaf
- Neurological Disorder Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Brit Mollenhauer
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
- Paracelsus-Elena-Klinik, Kassel, Germany
| | | | - Tiago F Outeiro
- German Center for Neurodegenerative Diseases (DZNE), Göttingen, Germany.
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.
- Max Planck Institute for Experimental Medicine, Göttingen, Germany.
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle, UK.
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38
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Vweza AO, Song CG, Chong KT. Liquid-Liquid Phase Separation in the Presence of Macromolecular Crowding and State-dependent Kinetics. Int J Mol Sci 2021; 22:6675. [PMID: 34206440 PMCID: PMC8268629 DOI: 10.3390/ijms22136675] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 06/13/2021] [Accepted: 06/14/2021] [Indexed: 12/27/2022] Open
Abstract
Biomolecular condensates formed via liquid-liquid phase separation (LLPS) are increasingly being shown to play major roles in cellular self-organization dynamics in health and disease. It is well established that macromolecular crowding has a profound impact on protein interactions, particularly those that lead to LLPS. Although synthetic crowding agents are used during in vitro LLPS experiments, they are considerably different from the highly crowded nucleo-/cytoplasm and the effects of in vivo crowding remain poorly understood. In this work, we applied computational modeling to investigate the effects of macromolecular crowding on LLPS. To include biologically relevant LLPS dynamics, we extended the conventional Cahn-Hilliard model for phase separation by coupling it to experimentally derived macromolecular crowding dynamics and state-dependent reaction kinetics. Through extensive field-theoretic computer simulations, we show that the inclusion of macromolecular crowding results in late-stage coarsening and the stabilization of relatively smaller condensates. At a high crowding concentration, there is an accelerated growth and late-stage arrest of droplet formation, effectively resulting in anomalous labyrinthine morphologies akin to protein gelation observed in experiments. These results not only elucidate the crowder effects observed in experiments, but also highlight the importance of including state-dependent kinetics in LLPS models, and may help in designing further experiments to probe the intricate roles played by LLPS in self-organization dynamics of cells.
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Affiliation(s)
- Alick-O. Vweza
- Department of Electronics and Information Engineering, Jeonbuk National University, Jeonju 54896, Korea; (A.-O.V.); (C.-G.S.)
| | - Chul-Gyu Song
- Department of Electronics and Information Engineering, Jeonbuk National University, Jeonju 54896, Korea; (A.-O.V.); (C.-G.S.)
- Advanced Biomedical Imaging Center, Jeonbuk National University, Jeonju 54896, Korea
| | - Kil-To Chong
- Department of Electronics and Information Engineering, Jeonbuk National University, Jeonju 54896, Korea; (A.-O.V.); (C.-G.S.)
- Advanced Electronics and Information Research Center, Jeonbuk National University, Jeonju 54896, Korea
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Hoffmann C, Sansevrino R, Morabito G, Logan C, Vabulas RM, Ulusoy A, Ganzella M, Milovanovic D. Synapsin Condensates Recruit alpha-Synuclein. J Mol Biol 2021; 433:166961. [PMID: 33774037 DOI: 10.1016/j.jmb.2021.166961] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 03/07/2021] [Accepted: 03/19/2021] [Indexed: 12/24/2022]
Abstract
Neurotransmission relies on the tight spatial and temporal regulation of the synaptic vesicle (SV) cycle. Nerve terminals contain hundreds of SVs that form tight clusters. These clusters represent a distinct liquid phase in which one component of the phase are SVs and the other synapsin 1, a highly abundant synaptic protein. Another major family of disordered proteins at the presynapse includes synucleins, most notably α-synuclein. The precise physiological role of α-synuclein in synaptic physiology remains elusive, albeit its role has been implicated in nearly all steps of the SV cycle. To determine the effect of α-synuclein on the synapsin phase, we employ the reconstitution approach using natively purified SVs from rat brains and the heterologous cell system to generate synapsin condensates. We demonstrate that synapsin condensates recruit α-synuclein, and while enriched into these synapsin condensates, α-synuclein still maintains its high mobility. The presence of SVs enhances the rate of synapsin/α-synuclein condensation, suggesting that SVs act as catalyzers for the formation of synapsin condensates. Notably, at physiological salt and protein concentrations, α-synuclein alone is not able to cluster isolated SVs. Excess of α-synuclein disrupts the kinetics of synapsin/SV condensate formation, indicating that the molar ratio between synapsin and α-synuclein is important in assembling the functional condensates of SVs. Understanding the molecular mechanism of α-synuclein interactions at the nerve terminals is crucial for clarifying the pathogenesis of synucleinopathies, where α-synuclein, synaptic proteins and lipid organelles all accumulate as insoluble intracellular inclusions.
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Affiliation(s)
- Christian Hoffmann
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Roberto Sansevrino
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Giuseppe Morabito
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Chinyere Logan
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - R Martin Vabulas
- Charité - Universitätsmedizin Berlin, Institute of Biochemistry, 10117 Berlin, Germany
| | - Ayse Ulusoy
- Laboratory of Neuroprotective Mechanisms, German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany
| | - Marcelo Ganzella
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany.
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40
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Feng Z, Wu X, Zhang M. Presynaptic bouton compartmentalization and postsynaptic density-mediated glutamate receptor clustering via phase separation. Neuropharmacology 2021; 193:108622. [PMID: 34051266 DOI: 10.1016/j.neuropharm.2021.108622] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/25/2021] [Accepted: 05/17/2021] [Indexed: 01/21/2023]
Abstract
Neuronal synapses encompass three compartments: presynaptic axon terminal, synaptic cleft, and postsynaptic dendrite. Each compartment contains densely packed molecular machineries that are involved in synaptic transmission. In recent years, emerging evidence indicates that the assembly of these membraneless substructures or assemblies that are not enclosed by membranes are driven by liquid-liquid phase separation. We review here recent studies that suggest the phase separation-mediated organization of these synaptic compartments. We discuss how synaptic function may be linked to its organization as biomolecular condensates. We conclude with a discussion of areas of future interest in the field for better understanding of the structural architecture of neuronal synapses and its contribution to synaptic functions.
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Affiliation(s)
- Zhe Feng
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xiandeng Wu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China.
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41
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An interaction between PRRT2 and Na +/K + ATPase contributes to the control of neuronal excitability. Cell Death Dis 2021; 12:292. [PMID: 33731672 PMCID: PMC7969623 DOI: 10.1038/s41419-021-03569-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 02/18/2021] [Accepted: 02/24/2021] [Indexed: 02/05/2023]
Abstract
Mutations in PRoline Rich Transmembrane protein 2 (PRRT2) cause pleiotropic syndromes including benign infantile epilepsy, paroxysmal kinesigenic dyskinesia, episodic ataxia, that share the paroxysmal character of the clinical manifestations. PRRT2 is a neuronal protein that plays multiple roles in the regulation of neuronal development, excitability, and neurotransmitter release. To better understand the physiopathology of these clinical phenotypes, we investigated PRRT2 interactome in mouse brain by a pulldown-based proteomic approach and identified α1 and α3 Na+/K+ ATPase (NKA) pumps as major PRRT2-binding proteins. We confirmed PRRT2 and NKA interaction by biochemical approaches and showed their colocalization at neuronal plasma membrane. The acute or constitutive inactivation of PRRT2 had a functional impact on NKA. While PRRT2-deficiency did not modify NKA expression and surface exposure, it caused an increased clustering of α3-NKA on the plasma membrane. Electrophysiological recordings showed that PRRT2-deficiency in primary neurons impaired NKA function during neuronal stimulation without affecting pump activity under resting conditions. Both phenotypes were fully normalized by re-expression of PRRT2 in PRRT2-deficient neurons. In addition, the NKA-dependent afterhyperpolarization that follows high-frequency firing was also reduced in PRRT2-silenced neurons. Taken together, these results demonstrate that PRRT2 is a physiological modulator of NKA function and suggest that an impaired NKA activity contributes to the hyperexcitability phenotype caused by PRRT2 deficiency.
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42
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Jähne S, Mikulasch F, Heuer HGH, Truckenbrodt S, Agüi-Gonzalez P, Grewe K, Vogts A, Rizzoli SO, Priesemann V. Presynaptic activity and protein turnover are correlated at the single-synapse level. Cell Rep 2021; 34:108841. [PMID: 33730575 DOI: 10.1016/j.celrep.2021.108841] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 12/18/2020] [Accepted: 02/17/2021] [Indexed: 11/15/2022] Open
Abstract
Synaptic transmission relies on the continual exocytosis and recycling of synaptic vesicles. Aged vesicle proteins are prevented from recycling and are eventually degraded. This implies that active synapses would lose vesicles and vesicle-associated proteins over time, unless the supply correlates to activity, to balance the losses. To test this hypothesis, we first model the quantitative relation between presynaptic spike rate and vesicle turnover. The model predicts that the vesicle supply needs to increase with the spike rate. To follow up this prediction, we measure protein turnover in individual synapses of cultured hippocampal neurons by combining nanoscale secondary ion mass spectrometry (nanoSIMS) and fluorescence microscopy. We find that turnover correlates with activity at the single-synapse level, but not with other parameters such as the abundance of synaptic vesicles or postsynaptic density proteins. We therefore suggest that the supply of newly synthesized proteins to synapses is closely connected to synaptic activity.
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Affiliation(s)
- Sebastian Jähne
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany.
| | - Fabian Mikulasch
- Max-Planck-Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077 Göttingen, Germany
| | - Helge G H Heuer
- Max-Planck-Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077 Göttingen, Germany; Faculty of Physics, Georg-August-University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Sven Truckenbrodt
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Paola Agüi-Gonzalez
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany; Center for Biostructural Imaging of Neurodegeneration (BIN), von Siebold Str. 3a, 37075 Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37073 Göttingen, Germany
| | - Katharina Grewe
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany; Center for Biostructural Imaging of Neurodegeneration (BIN), von Siebold Str. 3a, 37075 Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37073 Göttingen, Germany
| | - Angela Vogts
- NanoSIMS lab, Leibniz Institute for Baltic Sea Research Warnemünde (IOW), Seestraße 15, 18119 Rostock, Germany
| | - Silvio O Rizzoli
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany; Center for Biostructural Imaging of Neurodegeneration (BIN), von Siebold Str. 3a, 37075 Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37073 Göttingen, Germany.
| | - Viola Priesemann
- Max-Planck-Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077 Göttingen, Germany; Faculty of Physics, Georg-August-University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany; Bernstein-Center for Computational Neuroscience, Heinrich-Düker-Weg 12, 37073 Göttingen, Germany.
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43
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The vesicle cluster as a major organizer of synaptic composition in the short-term and long-term. Curr Opin Cell Biol 2021; 71:63-68. [PMID: 33706235 DOI: 10.1016/j.ceb.2021.02.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 01/22/2021] [Accepted: 02/04/2021] [Indexed: 01/29/2023]
Abstract
For decades, the synaptic vesicle cluster has been thought of as a storage space for synaptic vesicles, whose obvious function is to provide vesicles for the depolarization-induced release of neurotransmitters; however, reports over the last few years indicate that the synaptic vesicle cluster probably plays a much broader and more fundamental role in synaptic biology. Various experiments suggest that the cluster is able to regulate protein distribution and mobility in the synapse; moreover, it probably regulates cytoskeleton architecture, mediates the selective removal of synaptic components from the bouton, and controls the responses of the presynapse to plasticity. Here we discuss these features of the vesicle cluster and conclude that it serves as a key organizer of synaptic composition and dynamics.
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44
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Cao R, Kumar D, Dinsmore AD. Vesicle-Based Gel via Polyelectrolyte-Induced Adhesion: Structure, Rheology, and Response. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:1714-1724. [PMID: 33513022 DOI: 10.1021/acs.langmuir.0c02921] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We describe an experimental study of soft solids composed of micron-scale lipid bilayer vesicles that adhere to one another through electrostatic attraction to an oppositely charged polymer (PDADMAC). As the polymer concentration was increased, we found a fluid phase, a solid gel phase, and a gel composed of internally reorganized vesicles. Optical microscopy images showed a nearly close-packed structure of adhered vesicles that retained their closed-cell morphology. Shear rheology measurements showed that the gel phase is a solid with a modulus at the Pa scale and with linear response up to 70% strain. We found that the modulus depends on the energy per area of membrane-membrane adhesion but does not depend on the vesicle size. We further found that the gels survived osmotic stress or dilution of the adhering polymer but could be rapidly disrupted in response to the addition of strongly binding silica nanoparticles. These results demonstrate the potential for cell-sized lipid vesicles to form a solid platform that maintains the responsive properties of the membranes. Such materials may find applications as triggerable, protective coatings of delicate surfaces.
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Affiliation(s)
- Rui Cao
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Deepak Kumar
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Anthony D Dinsmore
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, United States
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45
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Park D, Wu Y, Lee SE, Kim G, Jeong S, Milovanovic D, De Camilli P, Chang S. Cooperative function of synaptophysin and synapsin in the generation of synaptic vesicle-like clusters in non-neuronal cells. Nat Commun 2021; 12:263. [PMID: 33431828 PMCID: PMC7801664 DOI: 10.1038/s41467-020-20462-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 12/02/2020] [Indexed: 02/01/2023] Open
Abstract
Clusters of tightly packed synaptic vesicles (SVs) are a defining feature of nerve terminals. While SVs are mobile within the clusters, the clusters have no boundaries consistent with a liquid phase. We previously found that purified synapsin, a peripheral SV protein, can assemble into liquid condensates and trap liposomes into them. How this finding relates to the physiological formation of SV clusters in living cells remains unclear. Here, we report that synapsin alone, when expressed in fibroblasts, has a diffuse cytosolic distribution. However, when expressed together with synaptophysin, an integral SV membrane protein previously shown to be localized on small synaptic-like microvesicles when expressed in non-neuronal cells, is sufficient to organize such vesicles in clusters highly reminiscent of SV clusters and with liquid-like properties. This minimal reconstitution system can be a powerful model to gain mechanistic insight into the assembly of structures which are of fundamental importance in synaptic transmission. Synaptic vesicle clusters were proposed to represent phase separated condensates. Here, the authors show that only two proteins, synapsin and synaptophysin, are sufficient to make vesicle clusters in fibroblasts which are similar to those found at synapses in morphology and liquid-like properties.
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Affiliation(s)
- Daehun Park
- Departments of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration and Repair, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Yumei Wu
- Departments of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration and Repair, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Sang-Eun Lee
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Goeun Kim
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Seonyoung Jeong
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Dragomir Milovanovic
- Departments of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration and Repair, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, 06510, USA.,Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Charitéplatz 1, 10117, Berlin, Germany
| | - Pietro De Camilli
- Departments of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration and Repair, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, 06510, USA.
| | - Sunghoe Chang
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, South Korea.
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Perego E, Reshetniak S, Lorenz C, Hoffmann C, Milovanović D, Rizzoli SO, Köster S. A minimalist model to measure interactions between proteins and synaptic vesicles. Sci Rep 2020; 10:21086. [PMID: 33273508 PMCID: PMC7713060 DOI: 10.1038/s41598-020-77887-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 11/17/2020] [Indexed: 02/03/2023] Open
Abstract
Protein dynamics in the synaptic bouton are still not well understood, despite many quantitative studies of synaptic structure and function. The complexity of the synaptic environment makes investigations of presynaptic protein mobility challenging. Here, we present an in vitro approach to create a minimalist model of the synaptic environment by patterning synaptic vesicles (SVs) on glass coverslips. We employed fluorescence correlation spectroscopy (FCS) to measure the mobility of monomeric enhanced green fluorescent protein (mEGFP)-tagged proteins in the presence of the vesicle patterns. We observed that the mobility of all eleven measured proteins is strongly reduced in the presence of the SVs, suggesting that they all bind to the SVs. The mobility observed in these conditions is within the range of corresponding measurements in synapses of living cells. Overall, our simple, but robust, approach should enable numerous future studies of organelle-protein interactions in general.
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Affiliation(s)
- Eleonora Perego
- Institute for X-Ray Physics, University of Göttingen, 37077, Göttingen, Germany
| | - Sofiia Reshetniak
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, 37075, Göttingen, Germany
| | - Charlotta Lorenz
- Institute for X-Ray Physics, University of Göttingen, 37077, Göttingen, Germany
| | - Christian Hoffmann
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117, Berlin, Germany
| | - Dragomir Milovanović
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117, Berlin, Germany
| | - Silvio O Rizzoli
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, 37075, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37073, Göttingen, Germany
| | - Sarah Köster
- Institute for X-Ray Physics, University of Göttingen, 37077, Göttingen, Germany. .,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37073, Göttingen, Germany.
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47
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Quantitative Synaptic Biology: A Perspective on Techniques, Numbers and Expectations. Int J Mol Sci 2020; 21:ijms21197298. [PMID: 33023247 PMCID: PMC7582872 DOI: 10.3390/ijms21197298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/24/2020] [Accepted: 09/28/2020] [Indexed: 12/31/2022] Open
Abstract
Synapses play a central role for the processing of information in the brain and have been analyzed in countless biochemical, electrophysiological, imaging, and computational studies. The functionality and plasticity of synapses are nevertheless still difficult to predict, and conflicting hypotheses have been proposed for many synaptic processes. In this review, we argue that the cause of these problems is a lack of understanding of the spatiotemporal dynamics of key synaptic components. Fortunately, a number of emerging imaging approaches, going beyond super-resolution, should be able to provide required protein positions in space at different points in time. Mathematical models can then integrate the resulting information to allow the prediction of the spatiotemporal dynamics. We argue that these models, to deal with the complexity of synaptic processes, need to be designed in a sufficiently abstract way. Taken together, we suggest that a well-designed combination of imaging and modelling approaches will result in a far more complete understanding of synaptic function than currently possible.
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48
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Silva PM, Puerner C, Seminara A, Bassilana M, Arkowitz RA. Secretory Vesicle Clustering in Fungal Filamentous Cells Does Not Require Directional Growth. Cell Rep 2020; 28:2231-2245.e5. [PMID: 31433995 DOI: 10.1016/j.celrep.2019.07.062] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 04/22/2019] [Accepted: 07/18/2019] [Indexed: 11/27/2022] Open
Abstract
During symmetry breaking, the highly conserved Rho GTPase Cdc42 becomes stabilized at a defined site via an amplification process. However, little is known about how a new polarity site is established in an already asymmetric cell-a critical process in a changing environment. The human fungal pathogen Candida albicans switches from budding to filamentous growth in response to external cues, a transition controlled by Cdc42. Here, we have used optogenetic manipulation of cell polarity to reset growth in asymmetric filamentous C. albicans cells. We show that increasing the level of active Cdc42 on the plasma membrane results in disruption of the exocyst subunit Sec3 localization and a striking de novo clustering of secretory vesicles. This new cluster of secretory vesicles is highly dynamic, moving by hops and jumps, until a new growth site is established. Our results reveal that secretory vesicle clustering can occur in the absence of directional growth.
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Affiliation(s)
- Patrícia M Silva
- Université Côte d'Azur, CNRS, INSERM, Institute of Biology Valrose (iBV), Parc Valrose, Nice, France
| | - Charles Puerner
- Université Côte d'Azur, CNRS, INSERM, Institute of Biology Valrose (iBV), Parc Valrose, Nice, France
| | - Agnese Seminara
- Université Côte d'Azur, CNRS, Institute Physics of Nice (INPHYNI), Ave. J. Vallot, Nice, France
| | - Martine Bassilana
- Université Côte d'Azur, CNRS, INSERM, Institute of Biology Valrose (iBV), Parc Valrose, Nice, France
| | - Robert A Arkowitz
- Université Côte d'Azur, CNRS, INSERM, Institute of Biology Valrose (iBV), Parc Valrose, Nice, France.
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Phase Separation in Membrane Biology: The Interplay between Membrane-Bound Organelles and Membraneless Condensates. Dev Cell 2020; 55:30-44. [PMID: 32726575 DOI: 10.1016/j.devcel.2020.06.033] [Citation(s) in RCA: 143] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/14/2020] [Accepted: 06/26/2020] [Indexed: 12/13/2022]
Abstract
In eukaryotic cells, various membrane-bound organelles compartmentalize diverse cellular activities in a spatially and temporally controlled manner. Numerous membraneless organelles assembled via liquid-liquid phase separation (LLPS), known as condensates, also facilitate compartmentalization of cellular functions. Emerging evidence shows that these two organelle types interact in many biological processes. Membranes modulate the biogenesis and dynamics of phase-separated condensates by serving as assembly platforms or by forming direct contacts. Phase separation of membrane-associated proteins participates in various trafficking events, such as clustering of vesicles for temporally controlled fusion and storage, and transport of membraneless condensates on membrane-bound organelles. Phase separation also acts in cargo trafficking pathways by sorting and docking cargos for translocon-mediated transport across membranes, by shuttling cargos through the nuclear pore complex, and by triggering the formation of surrounding autophagosomes for delivery to lysosomes. The coordinated actions of membrane-bound and membraneless organelles ensure spatiotemporal control of various cellular functions.
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50
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Wu X, Cai Q, Feng Z, Zhang M. Liquid-Liquid Phase Separation in Neuronal Development and Synaptic Signaling. Dev Cell 2020; 55:18-29. [PMID: 32726576 DOI: 10.1016/j.devcel.2020.06.012] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/27/2020] [Accepted: 06/09/2020] [Indexed: 01/09/2023]
Abstract
Formation of biomolecular condensates that are not enclosed by membranes via liquid-liquid phase separation (LLPS) is a general strategy that cells adopt to organize membraneless subcellular compartments for diverse functions. Neurons are highly polarized with elaborate branching and functional compartmentalization of their neurites, thus, raising additional demand for the proper subcellular localization of both membraneless and membrane-based organelles. Recent studies have provided evidence that several protein assemblies involved in the establishment of neuronal stem cell (NSC) polarity and in the asymmetric division of NSCs form distinct molecular condensates via LLPS. In synapses of adult neurons, molecular apparatuses controlling presynaptic neurotransmitter release and postsynaptic signaling transmission are also likely formed via LLPS. These molecular condensates, though not enclosed by lipid bilayers, directly associate with plasma membranes or membrane-based organelles, indicating that direct communication between membraneless and membrane-based organelles is a common theme in neurons and other types of cells.
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Affiliation(s)
- Xiandeng Wu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Qixu Cai
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Zhe Feng
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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