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Liang C, Carrel D, Singh NK, Hiester LL, Fanget I, Kim H, Firestein BL. Carboxypeptidase E Independently Changes Microtubule Glutamylation, Dendritic Branching, and Neuronal Migration. ASN Neuro 2022; 14:17590914211062765. [PMID: 35014548 PMCID: PMC8755936 DOI: 10.1177/17590914211062765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Neuronal migration and dendritogenesis are dependent on dynamic changes to the microtubule (MT) network. Among various factors that regulate MT dynamics and stability, post-translational modifications (PTMs) of MTs play a critical role in conferring specificity of regulatory protein binding to MTs. Thus, it is important to understand the regulation of PTMs during brain development as multiple developmental processes are dependent on MTs. In this study, we identified that carboxypeptidase E (CPE) changes tubulin polyglutamylation, a major PTM in the brain, and we examine the impact of CPE-mediated changes to polyglutamylation on cortical neuron migration and dendrite morphology. We show, for the first time, that overexpression of CPE increases the level of polyglutamylated α-tubulin while knockdown decreases the level of polyglutamylation. We also demonstrate that CPE-mediated changes to polyglutamylation are dependent on the CPE zinc-binding motif and that this motif is necessary for CPE action on p150Glued localization. However, overexpression of a CPE mutant that does not increase MT glutamylation mimics the effects of overexpression of wild type CPE on dendrite branching. Furthermore, although overexpression of wild type CPE does not alter cortical neuron migration, overexpression of the mutant may act in a dominant-negative manner as it decreases the number of neurons that reach the cortical plate (CP), as we previously reported for CPE knockdown. Overall, our data suggest that CPE changes MT glutamylation and redistribution of p150Glued and that this function of CPE is independent of its role in shaping dendrite development but plays a partial role in regulating cortical neuron migration.
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Affiliation(s)
- Chen Liang
- Department of Cell Biology and Neuroscience, Rutgers, 242612The State University of New Jersey, Piscataway, NJ, USA.,Molecular Biosciences Graduate Program, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Damien Carrel
- SPPIN Laboratory, 555089Université de Paris, Centre National de la Recherche Scientifique UMR 8003, Paris, France
| | - Nisha K Singh
- Department of Cell Biology and Neuroscience, Rutgers, 242612The State University of New Jersey, Piscataway, NJ, USA.,Molecular Biosciences Graduate Program, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Liam L Hiester
- Department of Cell Biology and Neuroscience, Rutgers, 242612The State University of New Jersey, Piscataway, NJ, USA
| | - Isabelle Fanget
- SPPIN Laboratory, 555089Université de Paris, Centre National de la Recherche Scientifique UMR 8003, Paris, France
| | - Hyuck Kim
- Department of Cell Biology and Neuroscience, Rutgers, 242612The State University of New Jersey, Piscataway, NJ, USA
| | - Bonnie L Firestein
- Department of Cell Biology and Neuroscience, Rutgers, 242612The State University of New Jersey, Piscataway, NJ, USA
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2
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Khamsing D, Lebrun S, Fanget I, Larochette N, Tourain C, de Sars V, Brunstein M, Oheim M, Carrel D, Darchen F, Desnos C. A role for BDNF- and NMDAR-induced lysosomal recruitment of mTORC1 in the regulation of neuronal mTORC1 activity. Mol Brain 2021; 14:112. [PMID: 34247625 PMCID: PMC8273036 DOI: 10.1186/s13041-021-00820-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 06/30/2021] [Indexed: 12/15/2022] Open
Abstract
Memory and long term potentiation require de novo protein synthesis. A key regulator of this process is mTORC1, a complex comprising the mTOR kinase. Growth factors activate mTORC1 via a pathway involving PI3-kinase, Akt, the TSC complex and the GTPase Rheb. In non-neuronal cells, translocation of mTORC1 to late endocytic compartments (LEs), where Rheb is enriched, is triggered by amino acids. However, the regulation of mTORC1 in neurons remains unclear. In mouse hippocampal neurons, we observed that BDNF and treatments activating NMDA receptors trigger a robust increase in mTORC1 activity. NMDA receptors activation induced a significant recruitment of mTOR onto lysosomes even in the absence of external amino acids, whereas mTORC1 was evenly distributed in neurons under resting conditions. NMDA receptor-induced mTOR translocation to LEs was partly dependent on the BDNF receptor TrkB, suggesting that BDNF contributes to the effect of NMDA receptors on mTORC1 translocation. In addition, the combination of Rheb overexpression and artificial mTORC1 targeting to LEs by means of a modified component of mTORC1 fused with a LE-targeting motif strongly activated mTOR. To gain spatial and temporal control over mTOR localization, we designed an optogenetic module based on light-sensitive dimerizers able to recruit mTOR on LEs. In cells expressing this optogenetic tool, mTOR was translocated to LEs upon photoactivation. In the absence of growth factor, this was not sufficient to activate mTORC1. In contrast, mTORC1 was potently activated by a combination of BDNF and photoactivation. The data demonstrate that two important triggers of synaptic plasticity, BDNF and NMDA receptors, synergistically power the two arms of the mTORC1 activation mechanism, i.e., mTORC1 translocation to LEs and Rheb activation. Moreover, they unmask a functional link between NMDA receptors and mTORC1 that could underlie the changes in the synaptic proteome associated with long-lasting changes in synaptic strength.
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Affiliation(s)
- Dany Khamsing
- Saints-Pères Paris Institute for the Neurosciences, Université de Paris, Centre National de la Recherche Scientifique UMR 8003, 45 rue des Saints Pères, 75006, Paris, France
| | - Solène Lebrun
- Saints-Pères Paris Institute for the Neurosciences, Université de Paris, Centre National de la Recherche Scientifique UMR 8003, 45 rue des Saints Pères, 75006, Paris, France
| | - Isabelle Fanget
- Saints-Pères Paris Institute for the Neurosciences, Université de Paris, Centre National de la Recherche Scientifique UMR 8003, 45 rue des Saints Pères, 75006, Paris, France
| | - Nathanaël Larochette
- Saints-Pères Paris Institute for the Neurosciences, Université de Paris, Centre National de la Recherche Scientifique UMR 8003, 45 rue des Saints Pères, 75006, Paris, France.,Université de Paris, Centre National de la Recherche Scientifique, INSERM, B3OA, Paris, France, Ecole Nationale Vétérinaire d'Alfort, B3OA, Maisons-Alfort, France
| | - Christophe Tourain
- Wavefront-Engineering Microscopy Group, Sorbonne Université, INSERM S968, CNRS UMR7210, Institut de la Vision, Paris, France
| | - Vincent de Sars
- Wavefront-Engineering Microscopy Group, Sorbonne Université, INSERM S968, CNRS UMR7210, Institut de la Vision, Paris, France
| | - Maia Brunstein
- Saints-Pères Paris Institute for the Neurosciences, Université de Paris, Centre National de la Recherche Scientifique UMR 8003, 45 rue des Saints Pères, 75006, Paris, France
| | - Martin Oheim
- Saints-Pères Paris Institute for the Neurosciences, Université de Paris, Centre National de la Recherche Scientifique UMR 8003, 45 rue des Saints Pères, 75006, Paris, France
| | - Damien Carrel
- Saints-Pères Paris Institute for the Neurosciences, Université de Paris, Centre National de la Recherche Scientifique UMR 8003, 45 rue des Saints Pères, 75006, Paris, France.
| | - François Darchen
- Saints-Pères Paris Institute for the Neurosciences, Université de Paris, Centre National de la Recherche Scientifique UMR 8003, 45 rue des Saints Pères, 75006, Paris, France.,Service de Psychiatrie Infanto-Juvénile, Centre Hospitalier de Gonesse, 2 Boulevard du 19 mars 1962, 95500, Gonesse, France
| | - Claire Desnos
- Saints-Pères Paris Institute for the Neurosciences, Université de Paris, Centre National de la Recherche Scientifique UMR 8003, 45 rue des Saints Pères, 75006, Paris, France.
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3
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Dubois L, Pietrancosta N, Cabaye A, Fanget I, Debacker C, Gilormini PA, Dansette PM, Dairou J, Biot C, Froissart R, Goupil-Lamy A, Bertrand HO, Acher FC, McCort-Tranchepain I, Gasnier B, Anne C. Amino Acids Bearing Aromatic or Heteroaromatic Substituents as a New Class of Ligands for the Lysosomal Sialic Acid Transporter Sialin. J Med Chem 2020; 63:8231-8249. [PMID: 32608236 DOI: 10.1021/acs.jmedchem.9b02119] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Sialin, encoded by the SLC17A5 gene, is a lysosomal sialic acid transporter defective in Salla disease, a rare inherited leukodystrophy. It also enables metabolic incorporation of exogenous sialic acids, leading to autoantibodies against N-glycolylneuraminic acid in humans. Here, we identified a novel class of human sialin ligands by virtual screening and structure-activity relationship studies. The ligand scaffold is characterized by an amino acid backbone with a free carboxylate, an N-linked aromatic or heteroaromatic substituent, and a hydrophobic side chain. The most potent compound, 45 (LSP12-3129), inhibited N-acetylneuraminic acid 1 (Neu5Ac) transport in a non-competitive manner with IC50 ≈ 2.5 μM, a value 400-fold lower than the KM for Neu5Ac. In vitro and molecular docking studies attributed the non-competitive character to selective inhibitor binding to the Neu5Ac site in a cytosol-facing conformation. Moreover, compound 45 rescued the trafficking defect of the pathogenic mutant (R39C) causing Salla disease. This new class of cell-permeant inhibitors provides tools to investigate the physiological roles of sialin and help develop pharmacological chaperones for Salla disease.
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Affiliation(s)
- Lilian Dubois
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, CNRS, UMR 8601, Université de Paris, F-75006 Paris, France
| | - Nicolas Pietrancosta
- Laboratoire des Biomolécules, LBM, Sorbonne Université, École Normale Supérieure, PSL University, CNRS, F-75005 Paris, France.,Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Sorbonne Université, INSERM, CNRS, F-75005 Paris, France
| | - Alexandre Cabaye
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, CNRS, UMR 8601, Université de Paris, F-75006 Paris, France.,BIOVIA, Dassault Systèmes, F-78140 Velizy-Villacoublay, France
| | - Isabelle Fanget
- SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Université de Paris, F-75006 Paris, France
| | - Cécile Debacker
- SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Université de Paris, F-75006 Paris, France
| | - Pierre-André Gilormini
- UMR 8576, UGSF, Unité de Glycobiologie et Fonctionnelle, Université de Lille, CNRS, F-59650 Lille, France
| | - Patrick M Dansette
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, CNRS, UMR 8601, Université de Paris, F-75006 Paris, France
| | - Julien Dairou
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, CNRS, UMR 8601, Université de Paris, F-75006 Paris, France
| | - Christophe Biot
- UMR 8576, UGSF, Unité de Glycobiologie et Fonctionnelle, Université de Lille, CNRS, F-59650 Lille, France
| | - Roseline Froissart
- Service de Biochimie et Biologie Moléculaire Grand Est, Centre de Biologie et de Pathologie Est, Hospices Civils de Lyon, F-69677 Bron, France
| | | | | | - Francine C Acher
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, CNRS, UMR 8601, Université de Paris, F-75006 Paris, France
| | - Isabelle McCort-Tranchepain
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, CNRS, UMR 8601, Université de Paris, F-75006 Paris, France
| | - Bruno Gasnier
- SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Université de Paris, F-75006 Paris, France
| | - Christine Anne
- SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Université de Paris, F-75006 Paris, France
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4
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Liang C, Carrel D, Omelchenko A, Kim H, Patel A, Fanget I, Firestein BL. Cortical Neuron Migration and Dendrite Morphology are Regulated by Carboxypeptidase E. Cereb Cortex 2019; 29:2890-2903. [PMID: 29982499 PMCID: PMC6611459 DOI: 10.1093/cercor/bhy155] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 06/08/2018] [Accepted: 06/12/2018] [Indexed: 12/28/2022] Open
Abstract
Higher brain function relies on proper development of the cerebral cortex, including correct positioning of neurons and dendrite morphology. Disruptions in these processes may result in various neurocognitive disorders. Mutations in the CPE gene, which encodes carboxypeptidase E (CPE), have been linked to depression and intellectual disability. However, it remains unclear whether CPE is involved in early brain development and in turn contributes to the pathophysiology of neurocognitive disorders. Here, we investigate the effects of CPE knockdown on early brain development and explore the functional significance of the interaction between CPE and its binding partner p150Glued. We demonstrate that CPE is required for cortical neuron migration and dendrite arborization. Furthermore, we show that expression of CPE-C10 redistributes p150Glued from the centrosome and that disruption of CPE interaction with p150Glued leads to abnormal neuronal migration and dendrite morphology, suggesting that a complex between CPE and p150Glued is necessary for proper neurodevelopment.
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Affiliation(s)
- Chen Liang
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ, USA
- Molecular Biosciences Graduate Program, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ, USA
| | - Damien Carrel
- Neurophotonics Laboratory, Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique UMR 8250, Paris, France
| | - Anton Omelchenko
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ, USA
- Neuroscience Graduate Program, Rutgers, The State University of New Jersey, 683 Hoes Lane West, USA
| | - Hyuck Kim
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ, USA
| | - Aashini Patel
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ, USA
| | - Isabelle Fanget
- Neurophotonics Laboratory, Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique UMR 8250, Paris, France
| | - Bonnie L Firestein
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ, USA
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5
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Bretou M, Jouannot O, Fanget I, Pierobon P, Larochette N, Gestraud P, Guillon M, Emiliani V, Gasman S, Desnos C, Lennon-Duménil AM, Darchen F. Cdc42 controls the dilation of the exocytotic fusion pore by regulating membrane tension. Mol Biol Cell 2014; 25:3195-209. [PMID: 25143404 PMCID: PMC4196869 DOI: 10.1091/mbc.e14-07-1229] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
On exocytosis, membrane fusion starts with the formation of a narrow fusion pore that must expand to allow the release of secretory compounds. The GTPase Cdc42 promotes fusion pore dilation in neuroendocrine cells by controlling membrane tension. Membrane fusion underlies multiple processes, including exocytosis of hormones and neurotransmitters. Membrane fusion starts with the formation of a narrow fusion pore. Radial expansion of this pore completes the process and allows fast release of secretory compounds, but this step remains poorly understood. Here we show that inhibiting the expression of the small GTPase Cdc42 or preventing its activation with a dominant negative Cdc42 construct in human neuroendocrine cells impaired the release process by compromising fusion pore enlargement. Consequently the mode of vesicle exocytosis was shifted from full-collapse fusion to kiss-and-run. Remarkably, Cdc42-knockdown cells showed reduced membrane tension, and the artificial increase of membrane tension restored fusion pore enlargement. Moreover, inhibiting the motor protein myosin II by blebbistatin decreased membrane tension, as well as fusion pore dilation. We conclude that membrane tension is the driving force for fusion pore dilation and that Cdc42 is a key regulator of this force.
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Affiliation(s)
- Marine Bretou
- Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France Institut National de la Santé et de la Recherche Médicale, U932, Institut Curie, 75005 Paris, France
| | - Ouardane Jouannot
- Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France
| | - Isabelle Fanget
- Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France
| | - Paolo Pierobon
- Institut National de la Santé et de la Recherche Médicale, U932, Institut Curie, 75005 Paris, France
| | - Nathanaël Larochette
- Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France
| | - Pierre Gestraud
- Institut Curie, Paris 75248, France Institut National de la Santé et de la Recherche Médicale, U900, Paris 75248, France Ecole des Mines ParisTech, Fontainebleau, 77300 France
| | - Marc Guillon
- Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France
| | - Valentina Emiliani
- Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France
| | - Stéphane Gasman
- Centre National de la Recherche Scientifique/UPR3212, Institut des Neurosciences Cellulaires et Intégratives, Université Strasbourg, 67084 Strasbourg, France
| | - Claire Desnos
- Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France
| | - Ana-Maria Lennon-Duménil
- Institut National de la Santé et de la Recherche Médicale, U932, Institut Curie, 75005 Paris, France
| | - François Darchen
- Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France
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Meunier A, Jouannot O, Fulcrand R, Fanget I, Bretou M, Karatekin E, Arbault S, Guille M, Darchen F, Lemaître F, Amatore C. Back Cover: Coupling Amperometry and Total Internal Reflection Fluorescence Microscopy at ITO Surfaces for Monitoring Exocytosis of Single Vesicles (Angew. Chem. Int. Ed. 22/2011). Angew Chem Int Ed Engl 2011. [DOI: 10.1002/anie.201102239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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7
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Meunier A, Jouannot O, Fulcrand R, Fanget I, Bretou M, Karatekin E, Arbault S, Guille M, Darchen F, Lemaître F, Amatore C. Rücktitelbild: Coupling Amperometry and Total Internal Reflection Fluorescence Microscopy at ITO Surfaces for Monitoring Exocytosis of Single Vesicles (Angew. Chem. 22/2011). Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201102239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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8
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Meunier A, Jouannot O, Fulcrand R, Fanget I, Bretou M, Karatekin E, Arbault S, Guille M, Darchen F, Lemaître F, Amatore C. Coupling amperometry and total internal reflection fluorescence microscopy at ITO surfaces for monitoring exocytosis of single vesicles. Angew Chem Int Ed Engl 2011; 50:5081-4. [PMID: 21523868 DOI: 10.1002/anie.201101148] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Indexed: 11/11/2022]
Affiliation(s)
- Anne Meunier
- Département de Chimie, Ecole Normale Supérieure UMR 8640 (CNRS-ENS-UPMC Univ Paris 06), 24 rue Lhomond, 75005 Paris, France
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9
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Meunier A, Jouannot O, Fulcrand R, Fanget I, Bretou M, Karatekin E, Arbault S, Guille M, Darchen F, Lemaître F, Amatore C. Coupling Amperometry and Total Internal Reflection Fluorescence Microscopy at ITO Surfaces for Monitoring Exocytosis of Single Vesicles. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201101148] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Desnos C, Huet S, Fanget I, Chapuis C, Böttiger C, Racine V, Sibarita JB, Henry JP, Darchen F. Myosin va mediates docking of secretory granules at the plasma membrane. J Neurosci 2007; 27:10636-45. [PMID: 17898234 PMCID: PMC6673143 DOI: 10.1523/jneurosci.1228-07.2007] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Myosin Va (MyoVa) is a prime candidate for controlling actin-based organelle motion in neurons and neuroendocrine cells. Its function in secretory granule (SG) trafficking was investigated in enterochromaffin cells by wide-field and total internal reflection fluorescence microscopy. The distribution of endogenous MyoVa partially overlapped with SGs and microtubules. Impairing MyoVa function by means of a truncated construct (MyoVa tail) or RNA interference prevented the formation of SG-rich regions at the cell periphery and reduced SG density in the subplasmalemmal region. Individual SG trajectories were tracked to analyze SG mobility. A wide distribution of their diffusion coefficient, D(xy), was observed. Almost immobile SGs (D(xy) < 5 x 10(-4) microm2 x s(-1)) were considered as docked at the plasma membrane based on two properties: (1) SGs that undergo exocytosis have a D(xy) below this threshold value for at least 2 s before fusion; (2) a negative autocorrelation of the vertical motion was found in subtrajectories with a D(xy) below the threshold. Using this criterion of docking, we found that the main effect of MyoVa inhibition was to reduce the number of docked granules, leading to reduced secretory responses. Surprisingly, this reduction was not attributable to a decreased transport of SGs toward release sites. In contrast, MyoVa silencing reduced the occurrence of long-lasting, but not short-lasting, docking periods. We thus propose that, despite its known motor activity, MyoVa directly mediates stable attachment of SGs at the plasma membrane.
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Affiliation(s)
- Claire Desnos
- Institut de Biologie Physico-Chimique, Centre National de la Recherche Scientifique, Unité Propre de Recherche 1929, Université Paris 7 Denis Diderot, 75005 Paris, France, and
| | - Sébastien Huet
- Institut de Biologie Physico-Chimique, Centre National de la Recherche Scientifique, Unité Propre de Recherche 1929, Université Paris 7 Denis Diderot, 75005 Paris, France, and
| | - Isabelle Fanget
- Institut de Biologie Physico-Chimique, Centre National de la Recherche Scientifique, Unité Propre de Recherche 1929, Université Paris 7 Denis Diderot, 75005 Paris, France, and
| | - Catherine Chapuis
- Institut de Biologie Physico-Chimique, Centre National de la Recherche Scientifique, Unité Propre de Recherche 1929, Université Paris 7 Denis Diderot, 75005 Paris, France, and
| | - Caroline Böttiger
- Institut de Biologie Physico-Chimique, Centre National de la Recherche Scientifique, Unité Propre de Recherche 1929, Université Paris 7 Denis Diderot, 75005 Paris, France, and
| | - Victor Racine
- Institut Curie, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144, 75248 Paris Cedex 05, France
| | - Jean-Baptiste Sibarita
- Institut Curie, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144, 75248 Paris Cedex 05, France
| | - Jean-Pierre Henry
- Institut de Biologie Physico-Chimique, Centre National de la Recherche Scientifique, Unité Propre de Recherche 1929, Université Paris 7 Denis Diderot, 75005 Paris, France, and
| | - François Darchen
- Institut de Biologie Physico-Chimique, Centre National de la Recherche Scientifique, Unité Propre de Recherche 1929, Université Paris 7 Denis Diderot, 75005 Paris, France, and
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11
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Tran VS, Huet S, Fanget I, Cribier S, Henry JP, Karatekin E. Characterization of sequential exocytosis in a human neuroendocrine cell line using evanescent wave microscopy and “virtual trajectory” analysis. Eur Biophys J 2007; 37:55-69. [PMID: 17440716 DOI: 10.1007/s00249-007-0161-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Revised: 03/16/2007] [Accepted: 03/20/2007] [Indexed: 11/30/2022]
Abstract
Secretion of hormones and other bioactive substances is a fundamental process for virtually all multicellular organisms. Using total internal reflection fluorescence microscopy (TIRFM), we have studied the calcium-triggered exocytosis of single, fluorescently labeled large, dense core vesicles in the human neuroendocrine BON cell line. Three types of exocytotic events were observed: (1) simple fusions (disappearance of a fluorescent spot by rapid diffusion of the dye released to the extracellular space), (2) "orphan" fusions for which only rapid dye diffusion, but not the parent vesicle, could be detected, and (3) events with incomplete or multi-step disappearance of a fluorescent spot. Although all three types were reported previously, only the first case is clearly understood. Here, thanks to a combination of two-color imaging, variable angle TIRFM, and novel statistical analyses, we show that the latter two types of events are generated by the same basic mechanism, namely shape retention of fused vesicle ghosts which become targets for sequential fusions with deeper lying vesicles. Overall, approximately 25% of all exocytotic events occur via sequential fusion. Secondary vesicles, located 200-300 nm away from the cell membrane are as fusion ready as primary vesicles located very near the cell membrane. These findings call for a fundamental shift in current models of regulated secretion in endocrine cells. Previously, sequential fusion had been studied mainly using two-photon imaging. To the best of our knowledge, this work constitutes the first quantitative report on sequential fusion using TIRFM, despite its long running and widespread use in studies of secretory mechanisms.
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Affiliation(s)
- Viet Samuel Tran
- Institut de Biologie Physico-Chimique, CNRS, UPR 1929, Université Paris 7 Denis Diderot, Paris, France
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Huet S, Karatekin E, Tran VS, Fanget I, Cribier S, Henry JP. Analysis of transient behavior in complex trajectories: application to secretory vesicle dynamics. Biophys J 2006; 91:3542-59. [PMID: 16891360 PMCID: PMC1614485 DOI: 10.1529/biophysj.105.080622] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Analysis of trajectories of dynamical biological objects, such as breeding ants or cell organelles, is essential to reveal the interactions they develop with their environments. Many previous works used a global characterization based on parameters calculated for entire trajectories. In cases where transient behavior was detected, this usually concerned only a particular type, such as confinement or directed motion. However, these approaches are not appropriate in situations in which the tracked objects may display many different types of transient motion. We have developed a method to exhaustively analyze different kinds of transient behavior that the tracked objects may exhibit. The method discriminates stalled periods, constrained and directed motions from random dynamics by evaluating the diffusion coefficient, the mean-square displacement curvature, and the trajectory asymmetry along individual trajectories. To detect transient motions of various durations, these parameters are calculated along trajectories using a rolling analysis window whose width is variable. The method was applied to the study of secretory vesicle dynamics in the subplasmalemmal region of human carcinoid BON cells. Analysis of transitions between transient motion periods, combined with plausible assumptions about the origin of each motion type, leads to a model of dynamical subplasmalemmal organization.
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Affiliation(s)
- Sébastien Huet
- Institut de Biologie Physico-Chimique, Centre National de la Recherche Scientifique, UPR 1929, Université Paris 7 Denis Diderot, Paris, F-75005, France
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Desnos C, Schonn JS, Huet S, Tran VS, El-Amraoui A, Raposo G, Fanget I, Chapuis C, Ménasché G, de Saint Basile G, Petit C, Cribier S, Henry JP, Darchen F. Rab27A and its effector MyRIP link secretory granules to F-actin and control their motion towards release sites. ACTA ACUST UNITED AC 2004; 163:559-70. [PMID: 14610058 PMCID: PMC2173641 DOI: 10.1083/jcb.200302157] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The GTPase Rab27A interacts with myosin-VIIa and myosin-Va via MyRIP or melanophilin and mediates melanosome binding to actin. Here we show that Rab27A and MyRIP are associated with secretory granules (SGs) in adrenal chromaffin cells and PC12 cells. Overexpression of Rab27A, GTPase-deficient Rab27A-Q78L, or MyRIP reduced secretory responses of PC12 cells. Amperometric recordings of single adrenal chromaffin cells revealed that Rab27A-Q78L and MyRIP reduced the sustained component of release. Moreover, these effects on secretion were partly suppressed by the actin-depolymerizing drug latrunculin but strengthened by jasplakinolide, which stabilizes the actin cortex. Finally, MyRIP and Rab27A-Q78L restricted the motion of SGs in the subplasmalemmal region of PC12 cells, as measured by evanescent-wave fluorescence microscopy. In contrast, the Rab27A-binding domain of MyRIP and a MyRIP construct that interacts with myosin-Va but not with actin increased the mobility of SGs. We propose that Rab27A and MyRIP link SGs to F-actin and control their motion toward release sites through the actin cortex.
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Affiliation(s)
- Claire Desnos
- Centre National de la Recherche Scientifique (CNRS) UPR 1929, Institut de Biologie Physico-Chimique, 75005 Paris, France
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