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Laporte MH, Chi KI, Caudal LC, Zhao N, Schwarz Y, Rolland M, Martinez-Hernandez J, Martineau M, Chatellard C, Denarier E, Mercier V, Lemaître F, Blot B, Moutaux E, Cazorla M, Perrais D, Lanté F, Bruns D, Fraboulet S, Hemming FJ, Kirchhoff F, Sadoul R. Alix is required for activity-dependent bulk endocytosis at brain synapses. PLoS Biol 2022; 20:e3001659. [PMID: 35658004 PMCID: PMC9200306 DOI: 10.1371/journal.pbio.3001659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 06/15/2022] [Accepted: 05/04/2022] [Indexed: 12/04/2022] Open
Abstract
In chemical synapses undergoing high frequency stimulation, vesicle components can be retrieved from the plasma membrane via a clathrin-independent process called activity-dependent bulk endocytosis (ADBE). Alix (ALG-2-interacting protein X/PDCD6IP) is an adaptor protein binding to ESCRT and endophilin-A proteins which is required for clathrin-independent endocytosis in fibroblasts. Alix is expressed in neurons and concentrates at synapses during epileptic seizures. Here, we used cultured neurons to show that Alix is recruited to presynapses where it interacts with and concentrates endophilin-A during conditions triggering ADBE. Using Alix knockout (ko) neurons, we showed that this recruitment, which requires interaction with the calcium-binding protein ALG-2, is necessary for ADBE. We also found that presynaptic compartments of Alix ko hippocampi display subtle morphological defects compatible with flawed synaptic activity and plasticity detected electrophysiologically. Furthermore, mice lacking Alix in the forebrain undergo less seizures during kainate-induced status epilepticus and reduced propagation of the epileptiform activity. These results thus show that impairment of ADBE due to the lack of neuronal Alix leads to abnormal synaptic recovery during physiological or pathological repeated stimulations. The adaptor protein Alix (PDCD6IP) is necessary for membrane shaping underlying various biological processes including endocytosis. This study shows that Alix mediates activity-dependent bulk endocytosis and is required for correct synaptic physiology under normal and pathological conditions.
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Affiliation(s)
- Marine H. Laporte
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Department of Cell Biology, University of Geneva, Geneva, Switzerland
- * E-mail: (MHL); (FK); (RS)
| | - Kwang Il Chi
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Laura C. Caudal
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Na Zhao
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Yvonne Schwarz
- Molecular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Marta Rolland
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - José Martinez-Hernandez
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad Castilla-La Mancha, Albacete, Spain
| | - Magalie Martineau
- Interdisciplinary Institute for Neuroscience, University of Bordeaux-CNRS UMR 5297, Bordeaux, France
| | - Christine Chatellard
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Institut de Biologie Structurale, University Grenoble Alpes—CNRS-CEA UMR 5075, Grenoble, France
| | - Eric Denarier
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Vincent Mercier
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Florent Lemaître
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Département des Neurosciences, Centre de Recherche du centre hospitalier de Montréal, Canada
| | - Béatrice Blot
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Eve Moutaux
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Maxime Cazorla
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Institut de Neuroscience la Timone, CNRS UMR7289, Marseille, France
| | - David Perrais
- Interdisciplinary Institute for Neuroscience, University of Bordeaux-CNRS UMR 5297, Bordeaux, France
| | - Fabien Lanté
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Dieter Bruns
- Molecular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Sandrine Fraboulet
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Institute for Advanced Biosciences, Univ. Grenoble Alpes—INSERM U1209—CNRS UMR 5309, Grenoble, France
| | - Fiona J. Hemming
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
- * E-mail: (MHL); (FK); (RS)
| | - Rémy Sadoul
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Institut de Biologie Structurale, University Grenoble Alpes—CNRS-CEA UMR 5075, Grenoble, France
- * E-mail: (MHL); (FK); (RS)
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2
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Meunier M, Guttin A, Ancelet S, Laurin D, Zannoni J, Lefebvre C, Tondeur S, Persoons V, Pezet M, Pernet-Gallay K, Chuffart F, Rousseaux S, Testard Q, Thevenon J, Jouzier C, Deleuze JF, Laulagnier K, Sadoul R, Chatellard C, Hainaut P, Polack B, Cahn JY, Issartel JP, Park S. Extracellular vesicles from myelodysplastic mesenchymal stromal cells induce DNA damage and mutagenesis of hematopoietic stem cells through miRNA transfer. Leukemia 2020; 34:2249-2253. [PMID: 32051530 DOI: 10.1038/s41375-020-0738-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 12/15/2019] [Accepted: 01/30/2020] [Indexed: 11/09/2022]
Affiliation(s)
- Mathieu Meunier
- Department of Hematology, CHU Grenoble Alpes, Grenoble, France.
- CNRS UMR 5309, INSERM, U1209, Université Grenoble Alpes, Institute for Advanced Bioscience, 38700, Grenoble, France.
| | - Audrey Guttin
- Grenoble Institut des Neurosciences, INSERM U836, Grenoble Alpes University, Grenoble, France
| | - Sarah Ancelet
- CNRS UMR 5309, INSERM, U1209, Université Grenoble Alpes, Institute for Advanced Bioscience, 38700, Grenoble, France
| | - David Laurin
- CNRS UMR 5309, INSERM, U1209, Université Grenoble Alpes, Institute for Advanced Bioscience, 38700, Grenoble, France
| | - Johanna Zannoni
- Department of Hematology, CHU Grenoble Alpes, Grenoble, France
- CNRS UMR 5309, INSERM, U1209, Université Grenoble Alpes, Institute for Advanced Bioscience, 38700, Grenoble, France
| | - Christine Lefebvre
- Laboratoire de Génétique des hémopathies, CHU Grenoble Alpes, Grenoble, France
| | - Sylvie Tondeur
- Laboratoire de Génétique des hémopathies, CHU Grenoble Alpes, Grenoble, France
| | - Virginie Persoons
- Unité de Thérapie et d'Ingénierie Cellulaire, EFS Auvergne Rhône Alpes et UF Génétique moléculaire et maladie héréditaire et oncologie, CHUGA, Grenoble, France
| | - Mylène Pezet
- CNRS UMR 5309, INSERM, U1209, Université Grenoble Alpes, Institute for Advanced Bioscience, 38700, Grenoble, France
| | - Karin Pernet-Gallay
- Grenoble Institut des Neurosciences, Plateforme de Microscopie électronique, Grenoble Alpes University, Grenoble, France
| | - Florent Chuffart
- CNRS UMR 5309, INSERM, U1209, Université Grenoble Alpes, Institute for Advanced Bioscience, 38700, Grenoble, France
| | - Sophie Rousseaux
- CNRS UMR 5309, INSERM, U1209, Université Grenoble Alpes, Institute for Advanced Bioscience, 38700, Grenoble, France
| | - Quentin Testard
- CNRS UMR 5309, INSERM, U1209, Université Grenoble Alpes, Institute for Advanced Bioscience, 38700, Grenoble, France
- Département de Génétique et Procréation, CHU Grenoble Alpes, Université Grenoble Alpes, Grenoble, France
- Bioinformatics Unit, Eurofins Biomnis, Lyon, France
| | - Julien Thevenon
- CNRS UMR 5309, INSERM, U1209, Université Grenoble Alpes, Institute for Advanced Bioscience, 38700, Grenoble, France
- Département de Génétique et Procréation, CHU Grenoble Alpes, Université Grenoble Alpes, Grenoble, France
| | - Claire Jouzier
- Department of Hematology, CHU Grenoble Alpes, Grenoble, France
- CNRS UMR 5309, INSERM, U1209, Université Grenoble Alpes, Institute for Advanced Bioscience, 38700, Grenoble, France
| | - Jean-François Deleuze
- Centre National de Génotypage, Institut de Génomique, Evry and Centre d'Etude du Polymorphisme Humain, 2 rue Gaston Crémieux, 91000, Paris, France
| | - Karine Laulagnier
- Grenoble Institut des Neurosciences, INSERM U836, Grenoble Alpes University, Grenoble, France
| | - Rémy Sadoul
- Grenoble Institut des Neurosciences, INSERM U836, Grenoble Alpes University, Grenoble, France
| | - Christine Chatellard
- Grenoble Institut des Neurosciences, INSERM U836, Grenoble Alpes University, Grenoble, France
| | - Pierre Hainaut
- CNRS UMR 5309, INSERM, U1209, Université Grenoble Alpes, Institute for Advanced Bioscience, 38700, Grenoble, France
| | - Benoît Polack
- Department of Hematology, CHU Grenoble Alpes, Grenoble, France
| | - Jean-Yves Cahn
- Department of Hematology, CHU Grenoble Alpes, Grenoble, France
| | - Jean-Paul Issartel
- Grenoble Institut des Neurosciences, INSERM U836, Grenoble Alpes University, Grenoble, France
| | - Sophie Park
- Department of Hematology, CHU Grenoble Alpes, Grenoble, France.
- CNRS UMR 5309, INSERM, U1209, Université Grenoble Alpes, Institute for Advanced Bioscience, 38700, Grenoble, France.
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Balaphas A, Meyer J, Sadoul R, Morel P, Gonelle-Gispert C, Bühler LH. Extracellular vesicles: Future diagnostic and therapeutic tools for liver disease and regeneration. Liver Int 2019; 39:1801-1817. [PMID: 31286675 DOI: 10.1111/liv.14189] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 06/06/2019] [Accepted: 07/01/2019] [Indexed: 02/13/2023]
Abstract
Extracellular vesicles are membrane fragments that can be produced by all cell types. Interactions between extracellular vesicles and various liver cells constitute an emerging field in hepatology and recent evidences have established a role for extracellular vesicles in various liver diseases and physiological processes. Extracellular vesicles originating from liver cells are implicated in intercellular communication and fluctuations of specific circulating extracellular vesicles could constitute new diagnostic tools. In contrast, extracellular vesicles derived from progenitor cells interact with hepatocytes or non-parenchymal cells, thereby protecting the liver from various injuries and promoting liver regeneration. Our review focuses on recent developments investigating the role of various types of extracellular vesicles in acute and chronic liver diseases as well as their potential use as biomarkers and therapeutic tools.
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Affiliation(s)
- Alexandre Balaphas
- Division of Digestive Surgery, University Hospitals of Geneva, Geneva, Switzerland.,Surgical Research Unit, University Hospitals of Geneva, Geneva, Switzerland.,Geneva Medical School, University Hospitals of Geneva, Geneva, Switzerland
| | - Jeremy Meyer
- Division of Digestive Surgery, University Hospitals of Geneva, Geneva, Switzerland.,Surgical Research Unit, University Hospitals of Geneva, Geneva, Switzerland.,Geneva Medical School, University Hospitals of Geneva, Geneva, Switzerland
| | - Rémy Sadoul
- Université Grenoble Alpes, Institut des Neurosciences, Grenoble, France
| | - Philippe Morel
- Division of Digestive Surgery, University Hospitals of Geneva, Geneva, Switzerland.,Surgical Research Unit, University Hospitals of Geneva, Geneva, Switzerland.,Geneva Medical School, University Hospitals of Geneva, Geneva, Switzerland
| | - Carmen Gonelle-Gispert
- Surgical Research Unit, University Hospitals of Geneva, Geneva, Switzerland.,Geneva Medical School, University Hospitals of Geneva, Geneva, Switzerland
| | - Leo Hans Bühler
- Division of Digestive Surgery, University Hospitals of Geneva, Geneva, Switzerland.,Surgical Research Unit, University Hospitals of Geneva, Geneva, Switzerland.,Geneva Medical School, University Hospitals of Geneva, Geneva, Switzerland
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4
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Laulagnier K, Javalet C, Hemming FJ, Chivet M, Lachenal G, Blot B, Chatellard C, Sadoul R. Amyloid precursor protein products concentrate in a subset of exosomes specifically endocytosed by neurons. Cell Mol Life Sci 2018; 75:757-773. [PMID: 28956068 PMCID: PMC11105273 DOI: 10.1007/s00018-017-2664-0] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [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: 03/30/2017] [Revised: 08/31/2017] [Accepted: 09/20/2017] [Indexed: 12/15/2022]
Abstract
Amyloid beta peptide (Aβ), the main component of senile plaques of Alzheimer's disease brains, is produced by sequential cleavage of amyloid precursor protein (APP) and of its C-terminal fragments (CTFs). An unanswered question is how amyloidogenic peptides spread throughout the brain during the course of the disease. Here, we show that small lipid vesicles called exosomes, secreted in the extracellular milieu by cortical neurons, carry endogenous APP and are strikingly enriched in CTF-α and the newly characterized CTF-η. Exosomes from N2a cells expressing human APP with the autosomal dominant Swedish mutation contain Aβ peptides as well as CTF-α and CTF-η, while those from cells expressing the non-mutated form of APP only contain CTF-α and CTF-η. APP and CTFs are sorted into a subset of exosomes which lack the tetraspanin CD63 and specifically bind to dendrites of neurons, unlike exosomes carrying CD63 which bind to both neurons and glial cells. Thus, neuroblastoma cells secrete distinct populations of exosomes carrying different cargoes and targeting specific cell types. APP-carrying exosomes can be endocytosed by receiving cells, allowing the processing of APP acquired by exosomes to give rise to the APP intracellular domain (AICD). Thus, our results show for the first time that neuronal exosomes may indeed act as vehicles for the intercellular transport of APP and its catabolites.
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Affiliation(s)
- Karine Laulagnier
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, 38042, Grenoble, France.
- Institut des Neurosciences, Université Grenoble Alpes, 38042, Grenoble, France.
| | - Charlotte Javalet
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, 38042, Grenoble, France
- Institut des Neurosciences, Université Grenoble Alpes, 38042, Grenoble, France
| | - Fiona J Hemming
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, 38042, Grenoble, France
- Institut des Neurosciences, Université Grenoble Alpes, 38042, Grenoble, France
| | - Mathilde Chivet
- Dulbecco Telethon Institute Lab of Neurodegenerative Diseases, Centre for Integrative Biology (CIBIO), University of Trento, 38123, Trento, Italy
| | - Gaëlle Lachenal
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, 38042, Grenoble, France
- Institut des Neurosciences, Université Grenoble Alpes, 38042, Grenoble, France
| | - Béatrice Blot
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, 38042, Grenoble, France
- Institut des Neurosciences, Université Grenoble Alpes, 38042, Grenoble, France
| | - Christine Chatellard
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, 38042, Grenoble, France
- Institut des Neurosciences, Université Grenoble Alpes, 38042, Grenoble, France
| | - Rémy Sadoul
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, 38042, Grenoble, France.
- Institut des Neurosciences, Université Grenoble Alpes, 38042, Grenoble, France.
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5
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Guo H, Chitiprolu M, Roncevic L, Javalet C, Hemming FJ, Trung MT, Meng L, Latreille E, Tanese de Souza C, McCulloch D, Baldwin RM, Auer R, Côté J, Russell RC, Sadoul R, Gibbings D. Atg5 Disassociates the V 1V 0-ATPase to Promote Exosome Production and Tumor Metastasis Independent of Canonical Macroautophagy. Dev Cell 2018; 43:716-730.e7. [PMID: 29257951 DOI: 10.1016/j.devcel.2017.11.018] [Citation(s) in RCA: 180] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 10/29/2017] [Accepted: 11/20/2017] [Indexed: 01/08/2023]
Abstract
Autophagy and autophagy-related genes (Atg) have been attributed prominent roles in tumorigenesis, tumor growth, and metastasis. Extracellular vesicles called exosomes are also implicated in cancer metastasis. Here, we demonstrate that exosome production is strongly reduced in cells lacking Atg5 and Atg16L1, but this is independent of Atg7 and canonical autophagy. Atg5 specifically decreases acidification of late endosomes where exosomes are produced, disrupting the acidifying V1V0-ATPase by removing a regulatory component, ATP6V1E1, into exosomes. The effect of Atg5 on exosome production promotes the migration and in vivo metastasis of orthotopic breast cancer cells. These findings uncover mechanisms controlling exosome release and identify means by which autophagy-related genes can contribute to metastasis in autophagy-independent pathways.
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Affiliation(s)
- Huishan Guo
- Department of Cellular and Molecular Medicine, University of Ottawa, 3131 Roger Guindon Hall, 451 Smyth Road, Ottawa K1H 8M5, Canada
| | - Maneka Chitiprolu
- Department of Cellular and Molecular Medicine, University of Ottawa, 3131 Roger Guindon Hall, 451 Smyth Road, Ottawa K1H 8M5, Canada
| | - Luc Roncevic
- Department of Cellular and Molecular Medicine, University of Ottawa, 3131 Roger Guindon Hall, 451 Smyth Road, Ottawa K1H 8M5, Canada
| | - Charlotte Javalet
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, 38042 Grenoble, France; Université Grenoble Alpes, Institut des Neurosciences, 38042 Grenoble, France
| | - Fiona J Hemming
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, 38042 Grenoble, France; Université Grenoble Alpes, Institut des Neurosciences, 38042 Grenoble, France
| | - My Tran Trung
- Department of Cellular and Molecular Medicine, University of Ottawa, 3131 Roger Guindon Hall, 451 Smyth Road, Ottawa K1H 8M5, Canada
| | - Lingrui Meng
- Department of Cellular and Molecular Medicine, University of Ottawa, 3131 Roger Guindon Hall, 451 Smyth Road, Ottawa K1H 8M5, Canada
| | - Elyse Latreille
- Department of Cellular and Molecular Medicine, University of Ottawa, 3131 Roger Guindon Hall, 451 Smyth Road, Ottawa K1H 8M5, Canada
| | | | - Danielle McCulloch
- Department of Cellular and Molecular Medicine, University of Ottawa, 3131 Roger Guindon Hall, 451 Smyth Road, Ottawa K1H 8M5, Canada
| | - R Mitchell Baldwin
- Department of Cellular and Molecular Medicine, University of Ottawa, 3131 Roger Guindon Hall, 451 Smyth Road, Ottawa K1H 8M5, Canada
| | - Rebecca Auer
- Ottawa Hospital Research Institute, Ottawa K1H 8L6, Canada
| | - Jocelyn Côté
- Department of Cellular and Molecular Medicine, University of Ottawa, 3131 Roger Guindon Hall, 451 Smyth Road, Ottawa K1H 8M5, Canada
| | - Ryan Charles Russell
- Department of Cellular and Molecular Medicine, University of Ottawa, 3131 Roger Guindon Hall, 451 Smyth Road, Ottawa K1H 8M5, Canada
| | - Rémy Sadoul
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, 38042 Grenoble, France; Université Grenoble Alpes, Institut des Neurosciences, 38042 Grenoble, France
| | - Derrick Gibbings
- Department of Cellular and Molecular Medicine, University of Ottawa, 3131 Roger Guindon Hall, 451 Smyth Road, Ottawa K1H 8M5, Canada; Ottawa Institute for System Biology, University of Ottawa, Ottawa K1H 8M5, Canada.
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6
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Williamson RL, Laulagnier K, Miranda AM, Fernandez MA, Wolfe MS, Sadoul R, Di Paolo G. Disruption of amyloid precursor protein ubiquitination selectively increases amyloid β (Aβ) 40 levels via presenilin 2-mediated cleavage. J Biol Chem 2017; 292:19873-19889. [PMID: 29021256 PMCID: PMC5712626 DOI: 10.1074/jbc.m117.818138] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [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: 09/17/2017] [Revised: 09/30/2017] [Indexed: 11/06/2022] Open
Abstract
Amyloid plaques, a neuropathological hallmark of Alzheimer's disease, are largely composed of amyloid β (Aβ) peptide, derived from cleavage of amyloid precursor protein (APP) by β- and γ-secretases. The endosome is increasingly recognized as an important crossroad for APP and these secretases, with major implications for APP processing and amyloidogenesis. Among various post-translational modifications affecting APP accumulation, ubiquitination of cytodomain lysines may represent a key signal controlling APP endosomal sorting. Here, we show that substitution of APP C-terminal lysines with arginine disrupts APP ubiquitination and that an increase in the number of substituted lysines tends to increase APP metabolism. An APP mutant lacking all C-terminal lysines underwent the most pronounced increase in processing, leading to accumulation of both secreted and intracellular Aβ40. Artificial APP ubiquitination with rapalog-mediated proximity inducers reduced Aβ40 generation. A lack of APP C-terminal lysines caused APP redistribution from endosomal intraluminal vesicles (ILVs) to the endosomal limiting membrane, with a subsequent decrease in APP C-terminal fragment (CTF) content in secreted exosomes, but had minimal effects on APP lysosomal degradation. Both the increases in secreted and intracellular Aβ40 were abolished by depletion of presenilin 2 (PSEN2), recently shown to be enriched on the endosomal limiting membrane compared with PSEN1. Our findings demonstrate that ubiquitin can act as a signal at five cytodomain-located lysines for endosomal sorting of APP. They further suggest that disruption of APP endosomal sorting reduces its sequestration in ILVs and results in PSEN2-mediated processing of a larger pool of APP-CTF on the endosomal membrane.
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Affiliation(s)
| | - Karine Laulagnier
- the Grenoble Institut des Neurosciences, Inserm, Grenoble 38042, France
| | - André M Miranda
- From the Department of Pathology and Cell Biology and
- the Life and Health Sciences Research Institute, School of Medicine, University of Minho and
- Life and Health Sciences Research Institute/3B's Research Group-Biomaterials, Biodegradables, and Biomimetics Associate Laboratory, 4710-057 Braga/Guimarães, Portugal, and
| | - Marty A Fernandez
- the Center for Neurologic Diseases, Harvard University, Boston, Massachusetts 02115
| | - Michael S Wolfe
- the Center for Neurologic Diseases, Harvard University, Boston, Massachusetts 02115
| | - Rémy Sadoul
- the Grenoble Institut des Neurosciences, Inserm, Grenoble 38042, France
| | - Gilbert Di Paolo
- From the Department of Pathology and Cell Biology and
- the Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, New York 10032
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7
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Sadoul R, Laporte MH, Chassefeyre R, Chi KI, Goldberg Y, Chatellard C, Hemming FJ, Fraboulet S. The role of ESCRT during development and functioning of the nervous system. Semin Cell Dev Biol 2017; 74:40-49. [PMID: 28811263 DOI: 10.1016/j.semcdb.2017.08.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 07/21/2017] [Accepted: 08/04/2017] [Indexed: 12/12/2022]
Abstract
The endosomal sorting complex required for transport (ESCRT) is made of subcomplexes (ESCRT 0-III), crucial to membrane remodelling at endosomes, nuclear envelope and cell surface. ESCRT-III shapes membranes and in most cases cooperates with the ATPase VPS4 to mediate fission of membrane necks from the inside. The first ESCRT complexes mainly serve to catalyse the formation of ESCRT-III but can be bypassed by accessory proteins like the Alg-2 interacting protein-X (ALIX). In the nervous system, ALIX/ESCRT controls the survival of embryonic neural progenitors and later on the outgrowth and pruning of axons and dendrites, all necessary steps to establish a functional brain. In the adult brain, ESCRTs allow the endosomal turn over of synaptic vesicle proteins while stable ESCRT complexes might serve as scaffolds for the postsynaptic parts. The necessity of ESCRT for the harmonious function of the brain has its pathological counterpart, the mutations in CHMP2B of ESCRT-III giving rise to several neurodegenerative diseases.
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Affiliation(s)
- Rémy Sadoul
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France; Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France.
| | - Marine H Laporte
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France; Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Romain Chassefeyre
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France; Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Kwang Il Chi
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France; Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Yves Goldberg
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France; Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Christine Chatellard
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France; Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Fiona J Hemming
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France; Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Sandrine Fraboulet
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France; Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
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8
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Laporte MH, Chatellard C, Vauchez V, Hemming FJ, Deloulme JC, Vossier F, Blot B, Fraboulet S, Sadoul R. Alix is required during development for normal growth of the mouse brain. Sci Rep 2017; 7:44767. [PMID: 28322231 PMCID: PMC5359572 DOI: 10.1038/srep44767] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 02/14/2017] [Indexed: 12/20/2022] Open
Abstract
Alix (ALG-2 interacting protein X) drives deformation and fission of endosomal and cell surface membranes and thereby intervenes in diverse biological processes including cell proliferation and apoptosis. Using embryonic fibroblasts of Alix knock-out mice, we recently demonstrated that Alix is required for clathrin-independent endocytosis. Here we show that mice lacking Alix suffer from severe reduction in the volume of the brain which affects equally all regions examined. The cerebral cortex of adult animals shows normal layering but is reduced in both medio-lateral length and thickness. Alix controls brain size by regulating its expansion during two distinct developmental stages. Indeed, embryonic surface expansion of the Alix ko cortex is reduced because of the loss of neural progenitors during a transient phase of apoptosis occurring between E11.5 and E12.5. Subsequent development of the Alix ko cortex occurs normally until birth, when Alix is again required for the post-natal radial expansion of the cortex through its capacity to allow proper neurite outgrowth. The need of Alix for both survival of neural progenitor cells and neurite outgrowth is correlated with its role in clathrin-independent endocytosis in neural progenitors and at growth cones. Thus Alix-dependent, clathrin independent endocytosis is essential for controlling brain size.
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Affiliation(s)
- Marine H. Laporte
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France
- Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Christine Chatellard
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France
- Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Victoria Vauchez
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France
- Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Fiona J. Hemming
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France
- Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Jean-Christophe Deloulme
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France
- Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Frédérique Vossier
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France
- Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Béatrice Blot
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France
- Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Sandrine Fraboulet
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France
- Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Rémy Sadoul
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38042 Grenoble, France
- Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
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9
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Vernay A, Therreau L, Blot B, Risson V, Dirrig-Grosch S, Waegaert R, Lequeu T, Sellal F, Schaeffer L, Sadoul R, Loeffler JP, René F. A transgenic mouse expressing CHMP2Bintron5 mutant in neurons develops histological and behavioural features of amyotrophic lateral sclerosis and frontotemporal dementia. Hum Mol Genet 2016; 25:3341-3360. [PMID: 27329763 DOI: 10.1093/hmg/ddw182] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 06/06/2016] [Accepted: 06/07/2016] [Indexed: 12/11/2022] Open
Abstract
Mutations in the charged multivesicular body protein 2B (CHMP2B) are associated with frontotemporal dementia (FTD), amyotrophic lateral sclerosis (ALS), and with a mixed ALS-FTD syndrome. To model this syndrome, we generated a transgenic mouse line expressing the human CHMP2Bintron5 mutant in a neuron-specific manner. These mice developed a dose-dependent disease phenotype. A longitudinal study revealed progressive gait abnormalities, reduced muscle strength and decreased motor coordination. CHMP2Bintron5 mice died due to generalized paralysis. When paralyzed, signs of denervation were present as attested by altered electromyographic profiles, by decreased number of fully innervated neuromuscular junctions, by reduction in size of motor endplates and by a decrease of sciatic nerve axons area. However, spinal motor neurons cell bodies were preserved until death. In addition to the motor dysfunctions, CHMP2Bintron5 mice progressively developed FTD-relevant behavioural modifications such as disinhibition, stereotypies, decrease in social interactions, compulsivity and change in dietary preferences. Furthermore, neurons in the affected spinal cord and brain regions showed accumulation of p62-positive cytoplasmic inclusions associated or not with ubiquitin and CHMP2Bintron5 As observed in FTD3 patients, these inclusions were negative for TDP-43 and FUS. Moreover, astrogliosis and microgliosis developed with age. Altogether, these data indicate that the neuronal expression of human CHMP2Bintron5 in areas involved in motor and cognitive functions induces progressive motor alterations associated with dementia symptoms and with histopathological hallmarks reminiscent of both ALS and FTD.
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Affiliation(s)
- Aurélia Vernay
- INSERM, U1118, Mécanismes Centraux et Périphériques de la Neurodégénérescence, F-67000 Strasbourg, France.,Université de Strasbourg, UMRS1118, Faculté de Médecine, Fédération de Médecine Translationelle de Strasbourg, F-67000 Strasbourg, France
| | - Ludivine Therreau
- INSERM, U1118, Mécanismes Centraux et Périphériques de la Neurodégénérescence, F-67000 Strasbourg, France.,Université de Strasbourg, UMRS1118, Faculté de Médecine, Fédération de Médecine Translationelle de Strasbourg, F-67000 Strasbourg, France
| | - Béatrice Blot
- INSERM U836, Grenoble Institut des Neurosciences, Université Joseph Fourier, F-38700 La Tronche, France
| | - Valérie Risson
- Laboratoire de Biologie Moléculaire de la Cellule, UMR5239 CNRS/ENS Lyon/UCBL/HCL Ecole normale supérieure de Lyon, F-69364 Lyon Cedex 07, France
| | - Sylvie Dirrig-Grosch
- INSERM, U1118, Mécanismes Centraux et Périphériques de la Neurodégénérescence, F-67000 Strasbourg, France.,Université de Strasbourg, UMRS1118, Faculté de Médecine, Fédération de Médecine Translationelle de Strasbourg, F-67000 Strasbourg, France
| | - Robin Waegaert
- INSERM, U1118, Mécanismes Centraux et Périphériques de la Neurodégénérescence, F-67000 Strasbourg, France.,Université de Strasbourg, UMRS1118, Faculté de Médecine, Fédération de Médecine Translationelle de Strasbourg, F-67000 Strasbourg, France
| | - Thiebault Lequeu
- INSERM, U1118, Mécanismes Centraux et Périphériques de la Neurodégénérescence, F-67000 Strasbourg, France.,Université de Strasbourg, UMRS1118, Faculté de Médecine, Fédération de Médecine Translationelle de Strasbourg, F-67000 Strasbourg, France
| | - François Sellal
- INSERM, U1118, Mécanismes Centraux et Périphériques de la Neurodégénérescence, F-67000 Strasbourg, France.,Neurology department, Hôpitaux civils and CMRR, F-68000 Colmar, France
| | - Laurent Schaeffer
- Laboratoire de Biologie Moléculaire de la Cellule, UMR5239 CNRS/ENS Lyon/UCBL/HCL Ecole normale supérieure de Lyon, F-69364 Lyon Cedex 07, France
| | - Rémy Sadoul
- INSERM U836, Grenoble Institut des Neurosciences, Université Joseph Fourier, F-38700 La Tronche, France
| | - Jean-Philippe Loeffler
- INSERM, U1118, Mécanismes Centraux et Périphériques de la Neurodégénérescence, F-67000 Strasbourg, France.,Université de Strasbourg, UMRS1118, Faculté de Médecine, Fédération de Médecine Translationelle de Strasbourg, F-67000 Strasbourg, France
| | - Frédérique René
- INSERM, U1118, Mécanismes Centraux et Périphériques de la Neurodégénérescence, F-67000 Strasbourg, France .,Université de Strasbourg, UMRS1118, Faculté de Médecine, Fédération de Médecine Translationelle de Strasbourg, F-67000 Strasbourg, France
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10
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Mercier V, Laporte MH, Destaing O, Blot B, Blouin CM, Pernet-Gallay K, Chatellard C, Saoudi Y, Albiges-Rizo C, Lamaze C, Fraboulet S, Petiot A, Sadoul R. ALG-2 interacting protein-X (Alix) is essential for clathrin-independent endocytosis and signaling. Sci Rep 2016; 6:26986. [PMID: 27244115 PMCID: PMC4886688 DOI: 10.1038/srep26986] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [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] [Received: 02/25/2016] [Accepted: 05/09/2016] [Indexed: 12/22/2022] Open
Abstract
The molecular mechanisms and the biological functions of clathrin independent endocytosis (CIE) remain largely elusive. Alix (ALG-2 interacting protein X), has been assigned roles in membrane deformation and fission both in endosomes and at the plasma membrane. Using Alix ko cells, we show for the first time that Alix regulates fluid phase endocytosis and internalization of cargoes entering cells via CIE, but has no apparent effect on clathrin mediated endocytosis or downstream endosomal trafficking. We show that Alix acts with endophilin-A to promote CIE of cholera toxin and to regulate cell migration. We also found that Alix is required for fast endocytosis and downstream signaling of the interleukin-2 receptor giving a first indication that CIE is necessary for activation of at least some surface receptors. In addition to characterizing a new function for Alix, our results highlight Alix ko cells as a unique tool to unravel the biological consequences of CIE.
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Affiliation(s)
- Vincent Mercier
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 1216, F-38042 Grenoble, France.,Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Marine H Laporte
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 1216, F-38042 Grenoble, France.,Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Olivier Destaing
- INSERM U1209, Grenoble, F-38042, France.,Université Grenoble Alpes, Institut Albert Bonniot, F-38000 Grenoble, France.,CNRS UMR 5309, F-38000 Grenoble, France
| | - Béatrice Blot
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 1216, F-38042 Grenoble, France.,Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Cédric M Blouin
- Institut Curie, PSL Research University, Membrane Dynamics and Mechanics of Intracellular Signaling Laboratory, Paris, France.,INSERM, U1143, Paris, France.,CNRS, UMR 3666, Paris, France
| | - Karin Pernet-Gallay
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 1216, F-38042 Grenoble, France.,Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Christine Chatellard
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 1216, F-38042 Grenoble, France.,Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Yasmina Saoudi
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 1216, F-38042 Grenoble, France.,Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Corinne Albiges-Rizo
- INSERM U1209, Grenoble, F-38042, France.,Université Grenoble Alpes, Institut Albert Bonniot, F-38000 Grenoble, France.,CNRS UMR 5309, F-38000 Grenoble, France
| | - Christophe Lamaze
- Institut Curie, PSL Research University, Membrane Dynamics and Mechanics of Intracellular Signaling Laboratory, Paris, France.,INSERM, U1143, Paris, France.,CNRS, UMR 3666, Paris, France
| | - Sandrine Fraboulet
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 1216, F-38042 Grenoble, France.,Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Anne Petiot
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 1216, F-38042 Grenoble, France.,Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
| | - Rémy Sadoul
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 1216, F-38042 Grenoble, France.,Université Grenoble Alpes, Institut des Neurosciences, F-38042 Grenoble, France
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11
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Chassefeyre R, Martínez-Hernández J, Bertaso F, Bouquier N, Blot B, Laporte M, Fraboulet S, Couté Y, Devoy A, Isaacs AM, Pernet-Gallay K, Sadoul R, Fagni L, Goldberg Y. Regulation of postsynaptic function by the dementia-related ESCRT-III subunit CHMP2B. J Neurosci 2015; 35:3155-73. [PMID: 25698751 PMCID: PMC4331633 DOI: 10.1523/jneurosci.0586-14.2015] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [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: 02/10/2014] [Revised: 12/23/2014] [Accepted: 01/06/2015] [Indexed: 12/14/2022] Open
Abstract
The charged multivesicular body proteins (Chmp1-7) are an evolutionarily conserved family of cytosolic proteins that transiently assembles into helical polymers that change the curvature of cellular membrane domains. Mutations in human CHMP2B cause frontotemporal dementia, suggesting that this protein may normally control some neuron-specific process. Here, we examined the function, localization, and interactions of neuronal Chmp2b. The protein was highly expressed in mouse brain and could be readily detected in neuronal dendrites and spines. Depletion of endogenous Chmp2b reduced dendritic branching of cultured hippocampal neurons, decreased excitatory synapse density in vitro and in vivo, and abolished activity-induced spine enlargement and synaptic potentiation. To understand the synaptic effects of Chmp2b, we determined its ultrastructural distribution by quantitative immuno-electron microscopy and its biochemical interactions by coimmunoprecipitation and mass spectrometry. In the hippocampus in situ, a subset of neuronal Chmp2b was shown to concentrate beneath the perisynaptic membrane of dendritic spines. In synaptoneurosome lysates, Chmp2b was stably bound to a large complex containing other members of the Chmp family, as well as postsynaptic scaffolds. The supramolecular Chmp assembly detected here corresponds to a stable form of the endosomal sorting complex required for transport-III (ESCRT-III), a ubiquitous cytoplasmic protein complex known to play a central role in remodeling of lipid membranes. We conclude that Chmp2b-containing ESCRT-III complexes are also present at dendritic spines, where they regulate synaptic plasticity. We propose that synaptic ESCRT-III filaments may function as a novel element of the submembrane cytoskeleton of spines.
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Affiliation(s)
- Romain Chassefeyre
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 836, F-38042 Grenoble, France, Université Grenoble Alpes, Grenoble Institut des Neurosciences (GIN), F-38042 Grenoble, France
| | - José Martínez-Hernández
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 836, F-38042 Grenoble, France, Université Grenoble Alpes, Grenoble Institut des Neurosciences (GIN), F-38042 Grenoble, France
| | - Federica Bertaso
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, F-34094 Montpellier, France, Universités de Montpellier 1 & 2, UMR-5203, F-34094 Montpellier, France, INSERM, Unité 661, F-34094 Montpellier, France
| | - Nathalie Bouquier
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, F-34094 Montpellier, France, Universités de Montpellier 1 & 2, UMR-5203, F-34094 Montpellier, France, INSERM, Unité 661, F-34094 Montpellier, France
| | - Béatrice Blot
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 836, F-38042 Grenoble, France, Université Grenoble Alpes, Grenoble Institut des Neurosciences (GIN), F-38042 Grenoble, France
| | - Marine Laporte
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 836, F-38042 Grenoble, France, Université Grenoble Alpes, Grenoble Institut des Neurosciences (GIN), F-38042 Grenoble, France
| | - Sandrine Fraboulet
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 836, F-38042 Grenoble, France, Université Grenoble Alpes, Grenoble Institut des Neurosciences (GIN), F-38042 Grenoble, France
| | - Yohann Couté
- INSERM, Unité 1038, F-38054 Grenoble, France, Commissariat à l'Energie Atomique (CEA), Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), Laboratoire de Biologie à Grande Echelle, F-38054 Grenoble, France
| | - Anny Devoy
- Department of Neurodegenerative Disease, University College London Institute of Neurology, London WC1N 3BG, United Kingdom, and
| | - Adrian M Isaacs
- Department of Neurodegenerative Disease, University College London Institute of Neurology, London WC1N 3BG, United Kingdom, and
| | - Karin Pernet-Gallay
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 836, F-38042 Grenoble, France, Université Grenoble Alpes, Grenoble Institut des Neurosciences (GIN), F-38042 Grenoble, France
| | - Rémy Sadoul
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 836, F-38042 Grenoble, France, Université Grenoble Alpes, Grenoble Institut des Neurosciences (GIN), F-38042 Grenoble, France,
| | - Laurent Fagni
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, F-34094 Montpellier, France, Universités de Montpellier 1 & 2, UMR-5203, F-34094 Montpellier, France, INSERM, Unité 661, F-34094 Montpellier, France
| | - Yves Goldberg
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 836, F-38042 Grenoble, France, Université Grenoble Alpes, Grenoble Institut des Neurosciences (GIN), F-38042 Grenoble, France, CEA, iRTSV, Groupe Physiopathologie du Cytosquelette (GPC), F-38054 Grenoble, France
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12
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Chivet M, Javalet C, Laulagnier K, Blot B, Hemming FJ, Sadoul R. Exosomes secreted by cortical neurons upon glutamatergic synapse activation specifically interact with neurons. J Extracell Vesicles 2014; 3:24722. [PMID: 25398455 PMCID: PMC4232649 DOI: 10.3402/jev.v3.24722] [Citation(s) in RCA: 208] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 09/16/2014] [Accepted: 09/17/2014] [Indexed: 12/22/2022] Open
Abstract
Exosomes are nano-sized vesicles of endocytic origin released into the extracellular space upon fusion of multivesicular bodies with the plasma membrane. Exosomes represent a novel mechanism of cell-cell communication allowing direct transfer of proteins, lipids and RNAs. In the nervous system, both glial and neuronal cells secrete exosomes in a way regulated by glutamate. It has been hypothesized that exosomes can be used for interneuronal communication implying that neuronal exosomes should bind to other neurons with some kind of specificity. Here, dissociated hippocampal cells were used to compare the specificity of binding of exosomes secreted by neuroblastoma cells to that of exosomes secreted by cortical neurons. We found that exosomes from neuroblastoma cells bind indiscriminately to neurons and glial cells and could be endocytosed preferentially by glial cells. In contrast, exosomes secreted from stimulated cortical neurons bound to and were endocytosed only by neurons. Thus, our results demonstrate for the first time that exosomes released upon synaptic activation do not bind to glial cells but selectively to other neurons suggesting that they can underlie a novel aspect of interneuronal communication.
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Affiliation(s)
- Mathilde Chivet
- Institut National de la Santé et de la Recherche Médicale (INSERM), U836, Grenoble, France; Grenoble Institute of Neuroscience, University of Grenoble Alpes, Grenoble, France
| | - Charlotte Javalet
- Institut National de la Santé et de la Recherche Médicale (INSERM), U836, Grenoble, France; Grenoble Institute of Neuroscience, University of Grenoble Alpes, Grenoble, France
| | - Karine Laulagnier
- Institut National de la Santé et de la Recherche Médicale (INSERM), U836, Grenoble, France; Grenoble Institute of Neuroscience, University of Grenoble Alpes, Grenoble, France
| | - Béatrice Blot
- Institut National de la Santé et de la Recherche Médicale (INSERM), U836, Grenoble, France; Grenoble Institute of Neuroscience, University of Grenoble Alpes, Grenoble, France
| | - Fiona J Hemming
- Institut National de la Santé et de la Recherche Médicale (INSERM), U836, Grenoble, France; Grenoble Institute of Neuroscience, University of Grenoble Alpes, Grenoble, France
| | - Rémy Sadoul
- Institut National de la Santé et de la Recherche Médicale (INSERM), U836, Grenoble, France; Grenoble Institute of Neuroscience, University of Grenoble Alpes, Grenoble, France;
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13
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Chivet M, Hemming F, Pernet-Gallay K, Fraboulet S, Sadoul R. Emerging role of neuronal exosomes in the central nervous system. Front Physiol 2012; 3:145. [PMID: 22654762 PMCID: PMC3361079 DOI: 10.3389/fphys.2012.00145] [Citation(s) in RCA: 164] [Impact Index Per Article: 13.7] [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: 03/14/2012] [Accepted: 04/30/2012] [Indexed: 12/24/2022] Open
Abstract
Exosomes are small extracellular vesicles, which stem from endosomes fusing with the plasma membrane, and can be recaptured by receiving cells. They contain lipids, proteins, and RNAs able to modify the physiology of receiving cells. Functioning of the brain relies on intercellular communication between neural cells. These communications can modulate the strength of responses at sparse groups of specific synapses, to modulate circuits underlying associations and memory. Expression of new genes must then follow to stabilize the long-term modifications of the synaptic response. Local changes of the physiology of synapses from one neuron driven by another, have so far been explained by classical signal transduction to modulate transcription, translation, and posttranslational modifications. In vitro evidence now demonstrates that exosomes are released by neurons in a way depending on synaptic activity; these exosomes can be retaken by other neurons suggesting a novel way for inter-neuronal communication. The efficacy of inter-neuronal transfer of biochemical information allowed by exosomes would be far superior to that of direct cell-to-cell contacts or secreted soluble factors. Indeed, lipids, proteins, and RNAs contained in exosomes secreted by emitting neurons could directly modify signal transduction and protein expression in receiving cells. Exosomes could thus represent an ideal mechanism for inter-neuronal transfer of information allowing anterograde and retrograde signaling across synapses necessary for plasticity. They might also allow spreading across the nervous system of pathological proteins like PrPsc, APP fragments, phosphorylated Tau, or Alpha-synuclein.
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Affiliation(s)
- Mathilde Chivet
- U836, Equipe 2, Neurodégénérescence et Plasticité, INSERM Grenoble, France
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14
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Bodon G, Chassefeyre R, Pernet-Gallay K, Martinelli N, Effantin G, Hulsik DL, Belly A, Goldberg Y, Chatellard-Causse C, Blot B, Schoehn G, Weissenhorn W, Sadoul R. Charged multivesicular body protein 2B (CHMP2B) of the endosomal sorting complex required for transport-III (ESCRT-III) polymerizes into helical structures deforming the plasma membrane. J Biol Chem 2011; 286:40276-86. [PMID: 21926173 DOI: 10.1074/jbc.m111.283671] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The endosomal sorting complexes required for transport (ESCRT-0-III) allow membrane budding and fission away from the cytosol. This machinery is used during multivesicular endosome biogenesis, cytokinesis, and budding of some enveloped viruses. Membrane fission is catalyzed by ESCRT-III complexes made of polymers of charged multivesicular body proteins (CHMPs) and by the AAA-type ATPase VPS4. How and which of the ESCRT-III subunits sustain membrane fission from the cytoplasmic surface remain uncertain. In vitro, CHMP2 and CHMP3 recombinant proteins polymerize into tubular helical structures, which were hypothesized to drive vesicle fission. However, this model awaits the demonstration that such structures exist and can deform membranes in cellulo. Here, we show that depletion of VPS4 induces specific accumulation of endogenous CHMP2B at the plasma membrane. Unlike other CHMPs, overexpressed full-length CHMP2B polymerizes into long, rigid tubes that protrude out of the cell. CHMP4s relocalize at the base of the tubes, the formation of which depends on VPS4. Cryo-EM of the CHMP2B membrane tubes demonstrates that CHMP2B polymerizes into a tightly packed helical lattice, in close association with the inner leaflet of the membrane tube. This association is tight enough to deform the lipid bilayer in cases where the tubular CHMP2B helix varies in diameter or is closed by domes. Thus, our observation that CHMP2B polymerization scaffolds membranes in vivo represents a first step toward demonstrating its structural role during outward membrane deformation.
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Affiliation(s)
- Gilles Bodon
- INSERM, U836, Equipe 2, Neurodégénérescence et Plasticité, Grenoble F-38042, France
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15
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Belly A, Bodon G, Blot B, Bouron A, Sadoul R, Goldberg Y. CHMP2B mutants linked to frontotemporal dementia impair maturation of dendritic spines. J Cell Sci 2010; 123:2943-54. [PMID: 20699355 DOI: 10.1242/jcs.068817] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [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] Open
Abstract
The highly conserved ESCRT-III complex is responsible for deformation and cleavage of membranes during endosomal trafficking and other cellular activities. In humans, dominant mutations in the ESCRT-III subunit CHMP2B cause frontotemporal dementia (FTD). The decade-long process leading to this cortical degeneration is not well understood. One possibility is that, akin to other neurodegenerative diseases, the pathogenic protein affects the integrity of dendritic spines and synapses before any neuronal death. Using confocal microscopy and 3D reconstruction, we examined whether expressing the FTD-linked mutants CHMP2B(intron5) and CHMP2B(Delta10) in cultured hippocampal neurons modified the number or structure of spines. Both mutants induced a significant decrease in the proportion of large spines with mushroom morphology, without overt degeneration. Furthermore, CHMP2B(Delta10) induced a drop in frequency and amplitude of spontaneous excitatory postsynaptic currents, suggesting that the more potent synapses were lost. These effects seemed unrelated to changes in autophagy. Depletion of endogenous CHMP2B by RNAi resulted in morphological changes similar to those induced by mutant CHMP2B, consistent with dominant-negative activity of pathogenic mutants. Thus, CHMP2B is required for spine growth. Taken together, these results demonstrate that a mutant ESCRT-III subunit linked to a human neurodegenerative disease can disrupt the normal pattern of spine development.
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Affiliation(s)
- Agnès Belly
- INSERM, Research Centre U836, F-38042 Grenoble, France
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16
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Grange J, Belly A, Dupas S, Trembleau A, Sadoul R, Goldberg Y. Specific interaction between Sam68 and neuronal mRNAs: implication for the activity-dependent biosynthesis of elongation factor eEF1A. J Neurosci Res 2009; 87:12-25. [PMID: 18711726 DOI: 10.1002/jnr.21824] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In cultured hippocampal neurons and in adult brain, the splicing regulatory protein Sam68 is partially relocated to the somatodendritic domain and associates with dendritic polysomes. Transfer to the dendrites is activity-dependent. We have investigated the repertoire of neuronal mRNAs to which Sam68 binds in vivo. By using coimmunoprecipitation and microarray screening techniques, Sam68 was found to associate with a number of plasticity-related mRNA species, including Eef1a1, an activity-responsive mRNA coding for translation elongation factor eEF1A. In cortical neuronal cultures, translation of the Eef1a1 mRNA was strongly induced by neuronal depolarisation and correlated with enhanced association of Sam68 with polysomal mRNAs. The possible function of Sam68 in Eef1a1 mRNA utilization was studied by expressing a dominant-negative, cytoplasmic Sam68 mutant (GFP-Sam68DeltaC) in cultured hippocampal neurons. The level of eEF1A was lower in neurons expressing GFP-Sam68DeltaC than in control neurons, supporting the proposal that endogenous Sam68 may contribute to the translational efficiency of the Eef1a1 mRNA. These findings are discussed in the light of the complex, potentially crucial regulation of eEF1A biosynthesis during long-term synaptic change.
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Affiliation(s)
- Julien Grange
- Université Joseph Fourier, Grenoble Institute of Neuroscience, Grenoble, France
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17
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Mahul-Mellier AL, Strappazzon F, Petiot A, Chatellard-Causse C, Torch S, Blot B, Freeman K, Kuhn L, Garin J, Verna JM, Fraboulet S, Sadoul R. Alix and ALG-2 are involved in tumor necrosis factor receptor 1-induced cell death. J Biol Chem 2008; 283:34954-65. [PMID: 18936101 PMCID: PMC3259881 DOI: 10.1074/jbc.m803140200] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 10/01/2008] [Indexed: 12/29/2022] Open
Abstract
Alix/AIP1 regulates cell death in a way involving interactions with the calcium-binding protein ALG-2 and with proteins of ESCRT (endosomal sorting complex required for transport). Using mass spectrometry we identified caspase-8 among proteins co-immunoprecipitating with Alix in dying neurons. We next demonstrated that Alix and ALG-2 interact with pro-caspase-8 and that Alix forms a complex with the TNFalpha receptor-1 (TNF-R1), depending on its capacity to bind ESCRT proteins. Thus, Alix and ALG-2 may allow the recruitment of pro-caspase-8 onto endosomes containing TNF-R1, a step thought to be necessary for activation of the apical caspase. In line with this, expression of Alix deleted of its ALG-2-binding site (AlixDeltaALG-2) significantly reduced TNF-R1-induced cell death, without affecting endocytosis of the receptor. In a more physiological setting, we found that programmed cell death of motoneurons, which can be inhibited by AlixDeltaALG-2, is regulated by TNF-R1. Taken together, these results highlight Alix and ALG-2 as new actors of the TNF-R1 pathway.
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Affiliation(s)
- Anne-Laure Mahul-Mellier
- INSERM, U836, Equipe 2,
Neurodégénérescence et Plasticité, Grenoble
F-38042, France, Commissariat à
l'Énergie Atomique, Departement des Sciences du Vivant Laboratoire
d'Etude de la Dynamique des Protéomes, Grenoble F-38054, France,
INSERM, U880, Grenoble F-38054, France, and the
Université Joseph Fourier, Grenoble
Institut des Neurosciences, Grenoble F-38042, France
| | - Flavie Strappazzon
- INSERM, U836, Equipe 2,
Neurodégénérescence et Plasticité, Grenoble
F-38042, France, Commissariat à
l'Énergie Atomique, Departement des Sciences du Vivant Laboratoire
d'Etude de la Dynamique des Protéomes, Grenoble F-38054, France,
INSERM, U880, Grenoble F-38054, France, and the
Université Joseph Fourier, Grenoble
Institut des Neurosciences, Grenoble F-38042, France
| | - Anne Petiot
- INSERM, U836, Equipe 2,
Neurodégénérescence et Plasticité, Grenoble
F-38042, France, Commissariat à
l'Énergie Atomique, Departement des Sciences du Vivant Laboratoire
d'Etude de la Dynamique des Protéomes, Grenoble F-38054, France,
INSERM, U880, Grenoble F-38054, France, and the
Université Joseph Fourier, Grenoble
Institut des Neurosciences, Grenoble F-38042, France
| | - Christine Chatellard-Causse
- INSERM, U836, Equipe 2,
Neurodégénérescence et Plasticité, Grenoble
F-38042, France, Commissariat à
l'Énergie Atomique, Departement des Sciences du Vivant Laboratoire
d'Etude de la Dynamique des Protéomes, Grenoble F-38054, France,
INSERM, U880, Grenoble F-38054, France, and the
Université Joseph Fourier, Grenoble
Institut des Neurosciences, Grenoble F-38042, France
| | - Sakina Torch
- INSERM, U836, Equipe 2,
Neurodégénérescence et Plasticité, Grenoble
F-38042, France, Commissariat à
l'Énergie Atomique, Departement des Sciences du Vivant Laboratoire
d'Etude de la Dynamique des Protéomes, Grenoble F-38054, France,
INSERM, U880, Grenoble F-38054, France, and the
Université Joseph Fourier, Grenoble
Institut des Neurosciences, Grenoble F-38042, France
| | - Béatrice Blot
- INSERM, U836, Equipe 2,
Neurodégénérescence et Plasticité, Grenoble
F-38042, France, Commissariat à
l'Énergie Atomique, Departement des Sciences du Vivant Laboratoire
d'Etude de la Dynamique des Protéomes, Grenoble F-38054, France,
INSERM, U880, Grenoble F-38054, France, and the
Université Joseph Fourier, Grenoble
Institut des Neurosciences, Grenoble F-38042, France
| | - Kimberley Freeman
- INSERM, U836, Equipe 2,
Neurodégénérescence et Plasticité, Grenoble
F-38042, France, Commissariat à
l'Énergie Atomique, Departement des Sciences du Vivant Laboratoire
d'Etude de la Dynamique des Protéomes, Grenoble F-38054, France,
INSERM, U880, Grenoble F-38054, France, and the
Université Joseph Fourier, Grenoble
Institut des Neurosciences, Grenoble F-38042, France
| | - Loriane Kuhn
- INSERM, U836, Equipe 2,
Neurodégénérescence et Plasticité, Grenoble
F-38042, France, Commissariat à
l'Énergie Atomique, Departement des Sciences du Vivant Laboratoire
d'Etude de la Dynamique des Protéomes, Grenoble F-38054, France,
INSERM, U880, Grenoble F-38054, France, and the
Université Joseph Fourier, Grenoble
Institut des Neurosciences, Grenoble F-38042, France
| | - Jérome Garin
- INSERM, U836, Equipe 2,
Neurodégénérescence et Plasticité, Grenoble
F-38042, France, Commissariat à
l'Énergie Atomique, Departement des Sciences du Vivant Laboratoire
d'Etude de la Dynamique des Protéomes, Grenoble F-38054, France,
INSERM, U880, Grenoble F-38054, France, and the
Université Joseph Fourier, Grenoble
Institut des Neurosciences, Grenoble F-38042, France
| | - Jean-Marc Verna
- INSERM, U836, Equipe 2,
Neurodégénérescence et Plasticité, Grenoble
F-38042, France, Commissariat à
l'Énergie Atomique, Departement des Sciences du Vivant Laboratoire
d'Etude de la Dynamique des Protéomes, Grenoble F-38054, France,
INSERM, U880, Grenoble F-38054, France, and the
Université Joseph Fourier, Grenoble
Institut des Neurosciences, Grenoble F-38042, France
| | - Sandrine Fraboulet
- INSERM, U836, Equipe 2,
Neurodégénérescence et Plasticité, Grenoble
F-38042, France, Commissariat à
l'Énergie Atomique, Departement des Sciences du Vivant Laboratoire
d'Etude de la Dynamique des Protéomes, Grenoble F-38054, France,
INSERM, U880, Grenoble F-38054, France, and the
Université Joseph Fourier, Grenoble
Institut des Neurosciences, Grenoble F-38042, France
| | - Rémy Sadoul
- INSERM, U836, Equipe 2,
Neurodégénérescence et Plasticité, Grenoble
F-38042, France, Commissariat à
l'Énergie Atomique, Departement des Sciences du Vivant Laboratoire
d'Etude de la Dynamique des Protéomes, Grenoble F-38054, France,
INSERM, U880, Grenoble F-38054, France, and the
Université Joseph Fourier, Grenoble
Institut des Neurosciences, Grenoble F-38042, France
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18
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Petiot A, Sadoul R. Autophagy discriminates between Alix and ESCRTs. Autophagy 2008; 5:106-7. [PMID: 19029801 DOI: 10.4161/auto.5.1.7277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Alix and ESCRT proteins are required for membrane fission during viral budding and egress and during the abscission stage of cytokinesis. These common roles have suggested that Alix functions as an ESCRT protein, a conclusion challenged by the finding that unlike ESCRTs, which control the formation of multivesicular endosomes, Alix does not influence the degradation of the EGF receptor. We previously showed that Alix controls neuronal death by an unknown mechanism, but dependent on its interaction with ESCRT proteins. Since then, numerous reports have shown that ESCRTs participate in macroautophagy. Given the direct interaction between ESCRTs and Alix, together with the known contribution of autophagy to cell death, it was hypothesized that Alix controls autophagy and thereby cell death. Our recent published results show that this is not the case. ESCRT protein activity therefore needs Alix for viral budding and cytokinesis but not for autophagy. The function of ESCRT can thus be clearly be disconnected from that of Alix.
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Affiliation(s)
- Anne Petiot
- INSERM U836 and Université Joseph Fourier, Grenoble Institute of Neurosciences (GIN), Grenoble, France
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19
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Petiot A, Strappazzon F, Chatellard-Causse C, Blot B, Torch S, Verna JM, Sadoul R. Alix differs from ESCRT proteins in the control of autophagy. Biochem Biophys Res Commun 2008; 375:63-8. [PMID: 18684393 DOI: 10.1016/j.bbrc.2008.07.136] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 07/22/2008] [Indexed: 11/25/2022]
Abstract
Alix/AIP1 is a cytosolic protein that regulates cell death through mechanisms that remain unclear. Alix binds to two protein members of the so-called Endosomal Sorting Complex Required for Transport (ESCRT), which facilitates membrane fission events during multivesicular endosome formation, enveloped virus budding and cytokinesis. Alix itself has been suggested to participate in these cellular events and is thus often considered to function in the ESCRT pathway. ESCRT proteins were recently implicated in autophagy, a process involved in bulk degradation of cytoplasmic constituents in lysosomes, which can also participate in cell death. In this study, we shown that, unlike ESCRT proteins, Alix is not involved in autophagy. These results strongly suggest that the capacity of several mutants of Alix to block both caspase-dependent and independent cell death does not relate to their capacity to modulate autophagy. Furthermore, they reinforce the conclusion of other studies demonstrating that the role of Alix is different from that of classical ESCRT proteins.
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Affiliation(s)
- Anne Petiot
- INSERM U836, Grenoble Institute of Neuroscience, F-38042 Grenoble, France.
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20
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Mabrouk K, Ram N, Boisseau S, Strappazzon F, Rehaim A, Sadoul R, Darbon H, Ronjat M, De Waard M. Critical amino acid residues of maurocalcine involved in pharmacology, lipid interaction and cell penetration. Biochimica et Biophysica Acta (BBA) - Biomembranes 2007; 1768:2528-40. [PMID: 17888395 DOI: 10.1016/j.bbamem.2007.06.030] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2006] [Revised: 06/05/2007] [Accepted: 06/07/2007] [Indexed: 11/22/2022]
Abstract
Maurocalcine (MCa) is a 33-amino acid residue peptide that was initially identified in the Tunisian scorpion Scorpio maurus palmatus. This peptide triggers interest for three main reasons. First, it helps unravelling the mechanistic basis of Ca(2+) mobilization from the sarcoplasmic reticulum because of its sequence homology with a calcium channel domain involved in excitation-contraction coupling. Second, it shows potent pharmacological properties because of its ability to activate the ryanodine receptor. Finally, it is of technological value because of its ability to carry cell-impermeable compounds across the plasma membrane. Herein, we characterized the molecular determinants that underlie the pharmacological and cell-penetrating properties of maurocalcine. We identify several key amino acid residues of the peptide that will help the design of cell-penetrating analogues devoid of pharmacological activity and cell toxicity. Close examination of the determinants underlying cell penetration of maurocalcine reveals that basic amino acid residues are required for an interaction with negatively charged lipids of the plasma membrane. Maurocalcine analogues that penetrate better have also stronger interaction with negatively charged lipids. Conversely, less effective analogues present a diminished ability to interact with these lipids. These findings will also help the design of still more potent cell penetrating analogues of maurocalcine.
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Affiliation(s)
- Kamel Mabrouk
- Laboratoire Chimie Biologie et Radicaux Libre, Universite Aix-Marseille, Avenue Escadrille Normandie Niemen, 13397 Marseille, France
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21
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Strappazzon F, Torch S, Trioulier Y, Blot B, Sadoul R, Verna JM. Survival response-linked Pyk2 activation during potassium depletion-induced apoptosis of cerebellar granule neurons. Mol Cell Neurosci 2006; 34:355-65. [PMID: 17188509 DOI: 10.1016/j.mcn.2006.11.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 10/27/2006] [Accepted: 11/14/2006] [Indexed: 11/16/2022] Open
Abstract
Numerous extracellular stimuli trigger trans-autophosphorylation at Tyr402 of Pyk2, inducing its activation. Pyk2 is a key mediator of several signaling pathways and has been implicated in apoptosis induced by specific stress signals. We investigated whether Pyk2 participates in cerebellar granule neuron (CGN) apoptosis induced by the suppression of membrane depolarization. We demonstrate that shifting CGN cultures from 25 mM to 5 mM KCl-containing medium induces an early, transient 70% increase in phosphorylated Tyr402 and Tyr580 Pyk2 levels that is triggered by Ca(2+) released from intracellular stores and mediated by calmodulin (CaM). Overexpression of Pyk2 increases CGN survival after 24 h by 70% compared to the control, thus suggesting that Pyk2 is involved in an anti-apoptotic response to K+ lowering. Furthermore, we show that CGN grown in K25 medium exhibit detectable CaM-dependent Pyk2 activity. When silencing Pyk2 activity by expressing a dominant-negative form, only 40% of the transfected neurons were alive 24 h after transfection when compared to the control. Overall, the present findings demonstrate for the first time that Pyk2 is a critical mediator of CGN survival.
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Affiliation(s)
- Flavie Strappazzon
- Institut National de la Santé et de la Recherche Médicale (INSERM), Laboratoire Neurodégénérescence et Plasticité, EMI108, France
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22
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Abstract
Alix/AIP1 (ALG-2-interacting protein X/apoptosis-linked-gene-2-interacting protein 1) is an adaptor protein that was first described for its capacity to bind to the calcium-binding protein ALG-2 (apoptosis-linked gene 2), the expression of which seemed necessary for cell death. Over-expression of truncated forms of Alix blocks caspase-dependent and -independent mechanisms of cell death. Numerous observations in yeast and in mammalian cells suggest that Alix controls the making of and trafficking through endosomes called MVBs (multivesicular bodies), which are crucial intermediates within the endolysosomal system. In particular, deletion of Bro1, one of the yeast homologues of Alix, leads to an impairment in the function of MVBs, leading to mis-sorting of proteins normally destined to the vacuole. Mammalian Alix may have a similar function and has been shown to bind to lyso(bis)phosphatidic acid, ESCRT (endosomal sorting complex required for transport) proteins, endophilins and CIN85 (Cbl-interacting protein of 85 kDa), which are all main regulators of the endosomal system. EIAV (equine infectious anaemia virus) and HIV late domains use Alix to recruit the ESCRT machinery in order to bud from the cell surface, underscoring the crucial role of the protein in orchestrating membrane deformation. In this review I develop the hypothesis that the normal function of Alix in the endolysosomal system may be deviated by ALG-2 towards a destructive role during active cell death.
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Affiliation(s)
- Rémy Sadoul
- Neurodégénérescence et Plasticité, E0108, INSERM/Université Joseph Fourier, Grenoble, France.
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23
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Mahul-Mellier AL, Hemming FJ, Blot B, Fraboulet S, Sadoul R. Alix, making a link between apoptosis-linked gene-2, the endosomal sorting complexes required for transport, and neuronal death in vivo. J Neurosci 2006; 26:542-9. [PMID: 16407552 PMCID: PMC6674414 DOI: 10.1523/jneurosci.3069-05.2006] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Alix/apoptosis-linked gene-2 (ALG-2)-interacting protein X is an adaptor protein involved in the regulation of the endolysosomal system through binding to endophilins and to endosomal sorting complexes required for transport (ESCRT) proteins, TSG101 and CHMP4b. It was first characterized as an interactor of ALG-2, a calcium-binding protein necessary for cell death, and several observations suggest a role for Alix in controlling cell death. We used electroporation in the chick embryo to test whether overexpressed wild-type or mutated Alix proteins influence cell death in vivo. We show that Alix overexpression is sufficient to induce cell death of neuroepithelial cells. This effect is strictly dependent on its capacity to bind to ALG-2. On the other hand, expression of Alix mutants lacking the ALG-2 or the CHMP4b binding sites prevents early programmed cell death in cervical motoneurons at day 4.5 of chick embryo development. This protection afforded by Alix mutants was abolished after deletion of the TSG101, but not of the endophilin, binding sites. Our results suggest that the interaction of the ALG-2/Alix complex with ESCRT proteins is necessary for naturally occurring death of motoneurons. Therefore, Alix represents a molecular link between the endolysosomal system and the cell death machinery.
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Affiliation(s)
- Anne-Laure Mahul-Mellier
- Institut National de la Santé et de la Recherche Médicale (INSERM), Laboratoire Neurodégénérescence et Plasticité, Equipe Mixte INSERM 0108, Universite Joseph Fourier, Grenoble I, F-38043 Grenoble, France
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24
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Estoppey S, Rodriguez I, Sadoul R, Martinou JC. Bcl-2 prevents activation of CPP32 cysteine protease and cleavage of poly (ADP-ribose) polymerase and U1-70 kD proteins in staurosporine-mediated apoptosis. Cell Death Differ 2006; 4:34-8. [PMID: 16465208 DOI: 10.1038/sj.cdd.4400205] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/1999] [Revised: 06/07/1999] [Accepted: 06/10/1999] [Indexed: 11/09/2022] Open
Abstract
Members of the the Bcl-2 and ICE/ced-3 gene families have been implicated as essential components in the control of the cell death pathway. Bcl-2 overexpression can prevent programmed cell death (PCD) in different cell types. ICE/ced-3-like proteases are synthesized as pro-enzymes and are activated by limited proteolysis. When overexpressed in diverse cell types, they trigger PCD. Bcl-2 can inhibit PCD mediated by these proteases, although as yet it is not clear at what specific step in the cell death pathway the protein acts. Here, we demonstrate that CPP32/Yama/Apopain, a member of the ICE/Ced-3 gene family, is processed during staurosporine-induced apoptosis in HeLa cells and that concomitant with CPP32 activation, two other proteins, poly (ADP-ribose) polymerase (PARP) and the U1-70 K small ribonucleoprotein, also undergo proteolysis. Overexpression of Bcl-2 prevents cleavage of CPP32, PARP and U1-70 K and protects HeLa cells from PCD. These results demonstrate that Bcl-2 controls PCD, by acting upstream of CPP32/Yama/Apopain.
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Affiliation(s)
- S Estoppey
- Glaxo Insititute for Molecular Biology, 14 chemin des Aulx, Plan-Les Ouates, Switzerland
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25
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Fauré J, Lachenal G, Court M, Hirrlinger J, Chatellard-Causse C, Blot B, Grange J, Schoehn G, Goldberg Y, Boyer V, Kirchhoff F, Raposo G, Garin J, Sadoul R. Exosomes are released by cultured cortical neurones. Mol Cell Neurosci 2006; 31:642-8. [PMID: 16446100 DOI: 10.1016/j.mcn.2005.12.003] [Citation(s) in RCA: 641] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Revised: 12/06/2005] [Accepted: 12/08/2005] [Indexed: 01/22/2023] Open
Abstract
Accumulating evidence shows that several cell types have the capacity to secrete membrane proteins by incorporating them into exosomes, which are small lipid vesicles derived from the intralumenal membranes of multivesicular bodies (MVBs) of the endocytic pathway. Exosomes are expelled in the extracellular space upon fusion of the MVB with the plasma membrane. Exosomal release is a way of secreting membrane proteins meant to be discarded, or to be passed on to other cells. Here, we demonstrate, using primary cortical cultures, that neurones and astrocytes can secrete exosomes. We find that exosomes released by cortical neurones contain the L1 cell adhesion molecule, the GPI-anchored prion protein, and the GluR2/3 but not the NR1 subunits of glutamate receptors. We also show that exosomal release is regulated by depolarisation. Our observation suggests that exosomes may have a regulatory function at synapses and could also allow intercellular exchange of membrane proteins within the brain.
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Affiliation(s)
- J Fauré
- Laboratoire Neurodégénérescence et Plasticité, INSERM-Université Joseph Fourier, Pavillon de Neurologie, Hopital A. Michallon, BP 217, 38043 Grenoble Cedex 9, France
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26
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Le Blanc I, Luyet PP, Pons V, Ferguson C, Emans N, Petiot A, Mayran N, Demaurex N, Fauré J, Sadoul R, Parton RG, Gruenberg J. Endosome-to-cytosol transport of viral nucleocapsids. Nat Cell Biol 2005; 7:653-64. [PMID: 15951806 PMCID: PMC3360589 DOI: 10.1038/ncb1269] [Citation(s) in RCA: 242] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2005] [Accepted: 05/10/2005] [Indexed: 12/22/2022]
Abstract
During viral infection, fusion of the viral envelope with endosomal membranes and nucleocapsid release were thought to be concomitant events. We show here that for the vesicular stomatitis virus they occur sequentially, at two successive steps of the endocytic pathway. Fusion already occurs in transport intermediates between early and late endosomes, presumably releasing the nucleocapsid within the lumen of intra-endosomal vesicles, where it remains hidden. Transport to late endosomes is then required for the nucleocapsid to be delivered to the cytoplasm. This last step, which initiates infection, depends on the late endosomal lipid lysobisphosphatidic acid (LBPA) and its putative effector Alix/AIP1, and is regulated by phosphatidylinositol-3-phosphate (PtdIns3P) signalling via the PtdIns3P-binding protein Snx16. We conclude that the nucleocapsid is exported into the cytoplasm after the back-fusion of internal vesicles with the limiting membrane of late endosomes, and that this process is controlled by the phospholipids LBPA and PtdIns3P and their effectors.
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Affiliation(s)
- Isabelle Le Blanc
- Biochemistry Department
University of Geneva30 quai E. Ansermet, 1211 Geneva 4,CH
- Department of Molecular and Cell Biology
University of California16 Barker Hall, Berkeley, CA 94720-3202,US
| | | | - Véronique Pons
- Biochemistry Department
University of Geneva30 quai E. Ansermet, 1211 Geneva 4,CH
| | - Charles Ferguson
- Institute for Molecular Bioscience
University of QueenslandCenter for Microscopy and Microanalysis, and School of Biomedical Sciences, Queensland 4072,AU
| | - Neil Emans
- Institut Pasteur de Corée
Institut Pasteur de CoréeRéseau International des Instituts Pasteur39-1, Hawolgok-dong, Sungbuk-gu, Seoul 136-791,KR
| | - Anne Petiot
- Biochemistry Department
University of Geneva30 quai E. Ansermet, 1211 Geneva 4,CH
- Glycobiologie et signalisation cellulaire
INSERM : U504Université Paris Sud - Paris XICentre de recherche Inserm 16, avenue Paul Vaillant Couturier 94807 Villejuif,FR
| | - Nathalie Mayran
- Biochemistry Department
University of Geneva30 quai E. Ansermet, 1211 Geneva 4,CH
- Institute of Experimental Pathology
Institute of Experimental Pathology25 Rue du Bugnon, 1011 Lausanne,CH
| | - Nicolas Demaurex
- Department of Physiology
Centre médical universitairerue Michel-Servet 1, 1211 Geneva 4,CH
| | - Julien Fauré
- Neurodegenerescence et Plasticite
INSERM : E108Université Joseph Fourier - Grenoble ICentre Hospitalier Universitaire 38043 GRENOBLE CEDEX 9,FR
| | - Rémy Sadoul
- Neurodegenerescence et Plasticite
INSERM : E108Université Joseph Fourier - Grenoble ICentre Hospitalier Universitaire 38043 GRENOBLE CEDEX 9,FR
| | - Robert G. Parton
- Institute for Molecular Bioscience
University of QueenslandCenter for Microscopy and Microanalysis, and School of Biomedical Sciences, Queensland 4072,AU
| | - Jean Gruenberg
- Biochemistry Department
University of Geneva30 quai E. Ansermet, 1211 Geneva 4,CH
- Correspondence should be adressed to: Jean Gruenberg
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Mattei S, Ryves WJ, Blot B, Sadoul R, Harwood AJ, Satre M, Klein G, Aubry L. Dd-Alix, a conserved endosome-associated protein, controls Dictyostelium development. Dev Biol 2005; 279:99-113. [PMID: 15708561 DOI: 10.1016/j.ydbio.2004.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2004] [Revised: 11/30/2004] [Accepted: 12/03/2004] [Indexed: 11/21/2022]
Abstract
We have characterized the Dictyostelium homolog of the mammalian protein Alix. Dd-Alix is encoded by a single gene and is expressed during vegetative growth and multicellular development. We showed that the alx null strain fails to complete its developmental program. Past the tight aggregate stage, morphogenesis is impaired, leading to markedly aberrant structures containing vacuolated and undifferentiated cells but no mature spores. The developmental defect is cell-autonomous as most cells remain of the PstB type even when mixed with wild-type cells. Complementation analysis with different Alix constructs allowed the identification of a 101-residue stretch containing a coiled-coil domain essential for Alix function. In addition, we showed that the protein associates in part with vesicular structures and that its distribution on a Percoll gradient overlaps that of the endocytic marker Vamp7. Dd-Alix also co-localizes with Dd-Vps32. In view of our data, and given the role of Vps32 proteins in membrane protein sorting and multivesicular body formation in yeast and mammals, we hypothesize that the developmental defects of the alx null strain result from abnormal trafficking of cell-surface receptors.
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Affiliation(s)
- Sara Mattei
- The Laboratoire de Biochimie et Biophysique des Systèmes Intégrés (UMR 5092 CNRS-CEA-UJF), DRDC, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
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Belly A, Moreau-Gachelin F, Sadoul R, Goldberg Y. Delocalization of the multifunctional RNA splicing factor TLS/FUS in hippocampal neurones: exclusion from the nucleus and accumulation in dendritic granules and spine heads. Neurosci Lett 2005; 379:152-7. [PMID: 15843054 DOI: 10.1016/j.neulet.2004.12.071] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2004] [Revised: 12/08/2004] [Accepted: 12/22/2004] [Indexed: 11/28/2022]
Abstract
Long-term synaptic change in the cortex and the hippocampus is believed to require the highly localized delivery and translation of mRNAs in the dendritic shafts and spines. The molecular interactions that underlie local signalling between synapses and mRNAs are still largely undefined. After purification from total brain extracts, the NMDA receptor is known to be associated with numerous proteins, including the multifunctional RNA-binding factor TLS (also called FUS). In non-neural tissue, TLS is a vital nuclear protein with roles in DNA repair, homologous recombination, transcriptional regulation and pre-mRNA processing. We have examined the distribution of TLS in hippocampal neurones, both in the adult brain and in mature primary cultures, using subcellular fractionation and immunofluorescence techniques. TLS immunoreactivity is largely excluded from the neuronal nucleus and is found in the cytosol and in somatodendritic particles. In some of these particles, TLS colocalizes with Sam68, a nuclear RNA-binding protein that we previously showed is incorporated into dendritic RNA granules. Some of the TLS clusters also colocalize with NMDA receptor clusters. Finally, TLS clusters are occasionally seen within spine heads. The apparent removal of TLS from the nucleus might result in specific patterns of mRNA transcription or splicing in hippocampal neurones. TLS may also contribute to steering, anchoring or regulating mRNAs at synaptic sites.
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Affiliation(s)
- Agnès Belly
- Laboratoire Neurodégénérescence et Plasticité, Université Joseph Fourier and INSERM EMI 0108, Pavillon de Neurologie, Centre Hospitalier Universitaire, F-38043 Grenoble cedex 9, France
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29
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Abstract
Apoptosis-linked gene-2 interacting protein X (Alix) is thought to be involved in both cell death and vesicular trafficking. We examined Alix expression 2 h, 6 h and 24 h after triggering seizure-dependent neuronal death by i.p. kainic acid injection. In the hippocampus, intense, transient immunolabelling was observed in the strata lucidum, oriens and radiatum, areas of high synaptic activity. The similarity of this distribution to those of synaptophysin and endophilin suggests a presynaptic localisation. Alix labelling was increased in neuronal cell bodies in kainate-sensitive regions before or concomitant with the first signs of oedema and/or neuronal eosinophilia. The increase persisted 24 h after kainate-injection in CA3 and the piriform cortex which are areas with massive swelling and numerous pyknotic neurons. This suggests that Alix may play an early role in the mechanisms leading to cell death. Taken together, our results suggest that Alix may be a molecular link between synaptic functioning and neuronal death.
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Affiliation(s)
- F J Hemming
- Neurodégénérescence et Plasticité, EMI 0108, INSERM/UJF, Hôpital A. Michallon, CHU, BP 217, 38043 Grenoble 9, France.
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Ben Fredj N, Grange J, Sadoul R, Richard S, Goldberg Y, Boyer V. Depolarization-induced translocation of the RNA-binding protein Sam68 to the dendrites of hippocampal neurons. J Cell Sci 2004; 117:1079-90. [PMID: 14996936 DOI: 10.1242/jcs.00927] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The traffic and expression of mRNAs in neurons are modulated by changes in neuronal activity. The regulation of neuronal RNA-binding proteins is therefore currently receiving attention. Sam68 is a ubiquitous nuclear RNA-binding protein implicated in post-transcriptional processes such as signal-dependent splice site selection. We show that Sam68 undergoes activity-responsive translocation to the soma and dendrites of hippocampal neurons in primary culture. In unstimulated neurons transiently expressing a GFP-Sam68 fusion protein, 90% of the cells accumulated the protein exclusively in the nucleus, and 4% showed extension of GFP-Sam68 to the dendrites. This nuclear expression pattern required the integrity of the Sam68 N-terminus. When present, the dendritic GFP-Sam68 formed granules, 26% of which were colocalized with ethidium bromide-stained RNA clusters. Most of the GFP-Sam68 granules were completely stationary, but a few moved in either a retrograde or anterograde direction. Following depolarization by 25 mM KCl, 50% of neurons displayed dendritic GFP-Sam68. GFP-Sam68 invaded the dendrites after 2 hours with high KCl, and returned to the nucleus within 3 hours after termination of the KCl treatment. A control GFP fusion derived from the SC-35 splicing factor remained fully nuclear during depolarization. No significant change was observed in the phosphorylation of Sam68 after depolarization. Translocation of Sam68 to the distal dendrites was microtubule dependent. Blockade of calcium channels with nimodipine abolished the translocation. Furthermore, inhibition of CRM-1-mediated nuclear export by leptomycin B partially prevented the depolarization-induced nuclear efflux of GFP-Sam68. These results support the possible involvement of Sam68 in the activity-dependent regulation of dendritic mRNAs.
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Affiliation(s)
- Naïla Ben Fredj
- Neurodégénérescence et Plasticité, INSERM EMI 01-08, Institut National de la Santé et de la Recherche Médicale, Pavillon de Neurologie, Centre Hospitalier Universitaire, 38043 Grenoble, France
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Grange J, Boyer V, Fabian-Fine R, Fredj NB, Sadoul R, Goldberg Y. Somatodendritic localization and mRNA association of the splicing regulatory protein Sam68 in the hippocampus and cortex. J Neurosci Res 2004; 75:654-66. [PMID: 14991841 DOI: 10.1002/jnr.20003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The RNA-binding protein Sam68 has been implicated in the signal-dependent processing of pre-mRNA and in the utilization of intron-containing retroviral mRNAs. Sam68 is predominantly nuclear but exhibits remarkable binding affinity for signalling proteins located at the membrane. We have investigated the subcellular distribution of Sam68 in adult rat cortex and hippocampus. Subcellular fractionation showed that the protein was most abundant in nuclei but also was present at a significant level in the cytosol and membrane fractions, including light and synaptic membranes derived from crude synaptosomes. Sam68 extracted from the synaptosomal fraction cosedimented with polysomes on sucrose gradients. In agreement with these findings, immunohistochemical staining indicated that Sam68 was concentrated in neuronal nuclei but was also detectable in the soma and dendrites. Sam68 immunoreactivity examined at the ultrastructural level was found to associate with dendritic microtubules, endoplasmic reticulum, and free polyribosomes, sometimes close to synapses. A combination of immunoprecipitation and RT-PCR directly confirmed that Sam68 was bound to polyadenylated mRNA in cortical lysates. The alphaCaMKII mRNA was identified as one of the coprecipitated transcripts; in contrast, the gephyrin and NR1-1 mRNAs were not coprecipitated, indicating a certain degree of sequence specificity in the association. In electrophoretic mobility shift assays, recombinant GST-Sam68 as well as brain-derived Sam68 bound with high affinity to the alphaCaMKII 3' untranslated region. These results suggest that Sam68 may accompany and, conceivably, regulate mature mRNAs during nuclear export, somatodendritic transport, and translation.
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Affiliation(s)
- Julien Grange
- Laboratoire Neurodégénérescence et Plasticité, INSERM EMI 01-08, Institut National de la Santé et de la Recherche Médicale, Pavillon de Neurologie, Centre Hospitalier Universitaire, Grenoble, France
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Matsuo H, Chevallier J, Mayran N, Le Blanc I, Ferguson C, Fauré J, Blanc NS, Matile S, Dubochet J, Sadoul R, Parton RG, Vilbois F, Gruenberg J. Role of LBPA and Alix in Multivesicular Liposome Formation and Endosome Organization. Science 2004; 303:531-4. [PMID: 14739459 DOI: 10.1126/science.1092425] [Citation(s) in RCA: 532] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
What are the components that control the assembly of subcellular organelles in eukaryotic cells? Although membranes can clearly be distorted by cytosolic factors, very little is known about the intrinsic mechanisms that control the biogenesis, shape, and organization of organellar membranes. Here, we found that the unconventional phospholipid lysobisphosphatidic acid (LBPA) could induce the formation of multivesicular liposomes that resembled the multivesicular endosomes that exist where this lipid is found in vivo. This process depended on the same pH gradient that exists across endosome membranes in vivo and was selectively controlled by Alix. In turn, Alix regulated the organization of LBPA-containing endosomes in vivo.
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Affiliation(s)
- Hirotami Matsuo
- Department of Biochemistry, University of Geneva, 30 quai Ernest Ansermet, 1211 Geneva 4, Switzerland
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Trioulier Y, Torch S, Blot B, Cristina N, Chatellard-Causse C, Verna JM, Sadoul R. Alix, a Protein Regulating Endosomal Trafficking, Is Involved in Neuronal Death. J Biol Chem 2004; 279:2046-52. [PMID: 14585841 DOI: 10.1074/jbc.m309243200] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alix/AIP1 is a cytoplasmic protein, which was first characterized as an interactor of ALG-2, a calcium-binding protein necessary for cell death. Alix has also recently been defined as a regulator of the endo-lysosomal system. Here we have used post-mitotic cerebellar neurons to test Alix function in caspase-dependent and -independent cell death. Indeed, these neurons survived when cultured in 25 mm potassium-containing medium but underwent apoptosis soon after the extracellular potassium was lowered to 5 mm. In agreement with other studies, we show that caspases are activated after K+ deprivation, but that inhibition of these proteases, using the pancaspase inhibitor boc-aspartyl(OMe)-fluoromethylketone, has no effect on cell survival. Transfection experiments demonstrated that Alix overexpression is sufficient to induce caspase activation, whereas overexpression of its C-terminal half, Alix-CT, blocks caspase activation and cell death after K+ deprivation. We also define a 12-amino acid PXY repeat of the C-terminal proline-rich domain necessary for binding ALG-2. Deletion of this domain in Alix or in Alix-CT abolished the effects of the overexpressed proteins on neuronal survival, demonstrating that the ALG-2-binding region is crucial for the death-modulating function of Alix. Overall, these findings define the Alix/ALG-2 complex as a regulator of cell death controlling both caspase-dependent and -independent pathways. They also suggest a molecular link between the endo-lysosomal system and the effectors of the cell death machinery.
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Affiliation(s)
- Yaël Trioulier
- Laboratoire Neurodégénérescence et Plasticité, INSERM-UJF, Pavillon de Neurologie, Hopital A. Michallon, 38043 Grenoble Cedex 9, France
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Abstract
Alix is a cytoplasmic protein involved in both programmed cell death and endocytosis (Oncogene 21 (2002) 6801). These activities of Alix may be related to its demonstrated capacity to bind ALG-2 (Apoptosis Linked Gene-2), CIN85/SETA and endophilins (J. Biol. Chem. 275 (2000) 19275; Science 271 (1996) 521; Cell Death Differ. 6 (1999) 124; J. Biol. Chem. 274 (1999) 1533; J. Biol. Chem. 28 (2002) 29108). Here we report for the first time the developmental expression pattern of Alix protein during chick development. We show by immunochemistry that the protein appears first in the ventral part of the rostral neural tube (stage 16 HH) and then in more caudal parts, thereby following the rostro-caudal maturation of the neural tube. Later on, the protein is found in the distal part of axons as well as in the dermomyotome where it becomes restricted to the muscle progenitors. This first demonstration of Alix modulation during development suggests a role for the protein in early phases of motoneuron and muscle growth and differentiation.
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Affiliation(s)
- Sandrine Fraboulet
- Laboratoire Neurodégénérescence et Plasticité, INSERM-UJF (EMI 0108), Hôpital A. Michallon, CHU, BP 217, 38043 Grenoble Cedex 9, France.
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Macé K, Saxod R, Feuerstein C, Sadoul R, Hemming FJ. Chondroitin and keratan sulfates have opposing effects on attachment and outgrowth of ventral mesencephalic explants in culture. J Neurosci Res 2002; 70:46-56. [PMID: 12237863 DOI: 10.1002/jnr.10381] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
During rat brain development, striatal proteoglycan (PG) expression shows specific spatio-temporal modifications suggesting a possible role in the guidance of its dopaminergic afferents. The effects of individual glycosaminoglycans (GAGs) on dopaminergic (DA) neuronal adhesion and outgrowth were therefore studied. We tested the behavior of dissociated embryonic rat mesencephalic cells cultivated on substrate-bound GAGs. Neuronal attachment was very limited and quantitative morphometry revealed variations in DA fiber outgrowth depending on the type and the concentration of GAG used. Next, we developed a cryoculture system to examine how neurons react toward GAGs expressed in situ. Rat brain slices from different developmental stages were used as substrates for embryonic mesencephalic explants. Preferential regions of adherence and outgrowth were observed: the striatum was found to be the most permissive, whereas the cortex was inhibitory. Western blotting experiments confirmed quantitative and qualitative changes in chondroitin sulfate (neurocan, phosphacan) and keratan sulfate (KS) containing PGs in these substrates and enzymatic digestion of GAGs before cryoculture revealed a substantial involvement of PGs in DA neuron adhesion and outgrowth. In particular, CSPGs seemed to mediate the permissive effect of the striatum, whereas KS confers an inhibitory effect to the cortex. PGs may thus be important for limiting midbrain projections to the striatum during development and for maintaining topography in the adult.
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Affiliation(s)
- K Macé
- Neurodégénérescence et Plasticité, CHU de Grenoble, Université Joseph Fourier, Pavillon de Neurologie, Grenoble, France.
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Aubry L, Mattei S, Blot B, Sadoul R, Satre M, Klein G. Biochemical characterization of two analogues of the apoptosis-linked gene 2 protein in Dictyostelium discoideum and interaction with a physiological partner in mammals, murine Alix. J Biol Chem 2002; 277:21947-54. [PMID: 11927596 DOI: 10.1074/jbc.m201718200] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two homologues, Dd-ALG-2a and Dd-ALG-2b, of the mammalian calcium-binding protein ALG-2 (apoptosis-linked gene 2) have been characterized in the cellular slime mold Dictyostelium discoideum. Fluorescence titrations showed that both proteins bind calcium ions with affinities (Ca2+)(0.5) of 30 and 450 microm, respectively, at sites specific to calcium. Calcium ion binding resulted in changes of conformation associated with the unmasking of hydrophobic regions of the proteins. Surface plasmon resonance analysis showed that Dd-ALG-2a homodimers formed (K(D) of 1 microm) at calcium ion concentrations similar to those necessary for Ca2+-induced conformational changes. Deletion of the hydrophobic N-terminal sequence or EF-hand 5 of Dd-ALG-2a prevented dimerization. The Dd-ALG-2b homodimer was not detected, and the Dd-ALG-2a/2b heterodimer formed only when Dd-ALG-2b was the immobilized partner. Murine Alix formed a heterodimer (K(D) = 0.6 microm) with Dd-ALG-2a but not with Dd-ALG-2b, and the interaction strictly depended upon calcium ions. The DeltaNter construct of Dd-ALG-2a lost its interaction capacity with mouse Alix. The genes encoding both proteins, Dd-alg-2a and -2b, were expressed in growing cells. The levels of mRNA were at a maximum during aggregation (4-8 h) and decreased rapidly thereafter. In contrast, the levels of proteins remained fairly stable. Dd-ALG-2a and Dd-ALG-2b were found to be dispensable for growth and development, based on the finding that single Dd-alg2a- or Dd-alg-2b- and double Dd-alg2a-/Dd-alg-2b- mutant cell lines showed normal growth in axenic medium or on bacterial lawns and exhibited unaltered development.
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Affiliation(s)
- Laurence Aubry
- Laboratoire de Biochimie et Biophysique des Systèmes Intégrés, Unité Mixte de Recherche 5092 CNRS-Commissariat à l'Energie Atomique-Université Joseph-Fourier, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
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Blum D, Torch S, Lambeng N, Nissou M, Benabid AL, Sadoul R, Verna JM. Molecular pathways involved in the neurotoxicity of 6-OHDA, dopamine and MPTP: contribution to the apoptotic theory in Parkinson's disease. Prog Neurobiol 2001; 65:135-72. [PMID: 11403877 DOI: 10.1016/s0301-0082(01)00003-x] [Citation(s) in RCA: 881] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Parkinson's disease (PD) is a neurodegenerative disorder characterized by a preferential loss of the dopaminergic neurons of the substantia nigra pars compacta. Although the etiology of PD is unknown, major biochemical processes such as oxidative stress and mitochondrial inhibition are largely described. However, despite these findings, the actual therapeutics are essentially symptomatical and are not able to block the degenerative process. Recent histological studies performed on brains from PD patients suggest that nigral cell death could be apoptotic. However, since post-mortem studies do not allow precise determination of the sequence of events leading to this apoptotic cell death, the molecular pathways involved in this process have been essentially studied on experimental models reproducing the human disease. These latter are created by using neurotoxic compounds such as 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or dopamine (DA). Extensive study of these models have shown that they mimick, in vitro and in vivo, the histological and/or the biochemical characteristics of PD and thus help to define important cellular actors of cell death presumably critical for the nigral degeneration. This review reports recent data concerning the biochemical and molecular apoptotic mechanisms underlying the experimental models of PD and correlates them to the phenomena occurring in human disease.
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Affiliation(s)
- D Blum
- Unité Mixte INSERM/UJF E0108, Neurodégénérescence et plasticité, CHU Michallon, Pavillon de Neurologie, BP217, 38043 Cedex 9, Grenoble, France.
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38
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Missotten M, Nichols A, Rieger K, Sadoul R. Alix, a novel mouse protein undergoing calcium-dependent interaction with the apoptosis-linked-gene 2 (ALG-2) protein. Cell Death Differ 1999; 6:124-9. [PMID: 10200558 DOI: 10.1038/sj.cdd.4400456] [Citation(s) in RCA: 197] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
ALG-2 is a EF hand calcium binding protein with sequence homologies to calmodulin. Vito et al have shown that ALG-2 expression is required for apoptosis following a number of death stimuli,1 although nothing is known about the effectors which underlie ALG-2 function. Here we have used ALG-2 as bait in a yeast two hybrid screen of a mouse brain cDNA library. We found that ALG-2 binds to itself and to a novel protein that we call ALG-2 interacting protein X, Alix. Using co-immunoprecipitation experiments, we confirmed ALG-2/ALG-2 binding and demonstrated that this interaction is calcium independent. ALG-2/Alix interaction was also validated by co-immunoprecipitation, but in this case, the binding was found to be strictly calcium dependent. Alix seems highly conserved throughout evolution since it shows significant homologies to a putative C. elegans protein (YNK-1) and to proteins of A. nidulans (PalA) and S. cerevisiae (BRO1). Alix is a potential regulator or downstream effector of ALG-2 action.
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Affiliation(s)
- M Missotten
- Serono Pharmaceutical Research Institute, 14 Chemin des Aulx, 1228 Plan les Ouates, Geneva, Switzerland
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Eskes R, Antonsson B, Osen-Sand A, Montessuit S, Richter C, Sadoul R, Mazzei G, Nichols A, Martinou JC. Bax-induced cytochrome C release from mitochondria is independent of the permeability transition pore but highly dependent on Mg2+ ions. J Cell Biol 1998; 143:217-24. [PMID: 9763433 PMCID: PMC2132823 DOI: 10.1083/jcb.143.1.217] [Citation(s) in RCA: 518] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Bcl-2 family members either promote or repress programmed cell death. Bax, a death-promoting member, is a pore-forming, mitochondria-associated protein whose mechanism of action is still unknown. During apoptosis, cytochrome C is released from the mitochondria into the cytosol where it binds to APAF-1, a mammalian homologue of Ced-4, and participates in the activation of caspases. The release of cytochrome C has been postulated to be a consequence of the opening of the mitochondrial permeability transition pore (PTP). We now report that Bax is sufficient to trigger the release of cytochrome C from isolated mitochondria. This pathway is distinct from the previously described calcium-inducible, cyclosporin A-sensitive PTP. Rather, the cytochrome C release induced by Bax is facilitated by Mg2+ and cannot be blocked by PTP inhibitors. These results strongly suggest the existence of two distinct mechanisms leading to cytochrome C release: one stimulated by calcium and inhibited by cyclosporin A, the other Bax dependent, Mg2+ sensitive but cyclosporin insensitive.
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Affiliation(s)
- R Eskes
- Serono Pharmaceutical Research Institute, 1228 Plan-les-Ouates, Geneva, Switzerland
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Abstract
Neuronal death is an essential feature in the normal development of the nervous system and in neurodegenerative states of the adult or ageing brain. Bcl-2 is the prototype of a growing family of proteins which control cell death. Many of these proteins are expressed in the nervous system during development and in the adult. Numerous observations have suggested that this family of proteins plays a central role in the control of naturally occurring and pathological neuronal death. In this review, I will discuss the possible mechanisms of action of these proteins as well as their potential use in treating neurodegenerative diseases.
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Affiliation(s)
- R Sadoul
- Serono Pharmaceutical Research Institute, 14 chemin des Aulx, 1228 Plan les Ouates, Geneva, Switzerland.
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41
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Abstract
We show that the pro-apoptotic proteins Bax and Bak trigger apoptosis when over-expressed in sympathetic neurons cultured in the presence of NGF. This effect can be blocked with z-VAD-fmk, a peptide inhibitor of caspases, but not with anti-apoptotic chemical compounds such as antioxidants or proteasome inhibitors. These results demonstrate that in sympathetic neurons Bax and Bak are sufficient to induce apoptosis in the absence of any other apparent cell death stimulus and that their effect is mediated by caspases but does not require reactive oxygen species nor activity of the proteasome.
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Affiliation(s)
- I Martinou
- Geneva Biomedical Research Institute, Plan-Les-Ouates, Glaxo-Wellcome, Switzerland
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42
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Antonsson B, Conti F, Ciavatta A, Montessuit S, Lewis S, Martinou I, Bernasconi L, Bernard A, Mermod JJ, Mazzei G, Maundrell K, Gambale F, Sadoul R, Martinou JC. Inhibition of Bax channel-forming activity by Bcl-2. Science 1997; 277:370-2. [PMID: 9219694 DOI: 10.1126/science.277.5324.370] [Citation(s) in RCA: 772] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Proteins of the Bcl-2 family are intracellular membrane-associated proteins that regulate programmed cell death (apoptosis) either positively or negatively by as yet unknown mechanisms. Bax, a pro-apoptotic member of the Bcl-2 family, was shown to form channels in lipid membranes. Bax triggered the release of liposome-encapsulated carboxyfluorescein at both neutral and acidic pH. At physiological pH, release could be blocked by Bcl-2. Bcl-2, in contrast, triggered carboxyfluorescein release at acidic pH only. In planar lipid bilayers, Bax formed pH- and voltage-dependent ion-conducting channels. Thus, the pro-apoptotic effects of Bax may be elicited through an intrinsic pore-forming activity that can be antagonized by Bcl-2.
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Affiliation(s)
- B Antonsson
- Geneva Biomedical Research Institute, Glaxo Wellcome R&D S. A., 1288 Plan les Ouates, Geneva, Switzerland.
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43
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Mermod JJ, Kruithof EK, Alouani S, Quiquerez AL, Sadoul R. ApoE genotype does not affect plasma tPA and PAI-1 antigen levels. Am J Med Genet 1997; 74:172-5. [PMID: 9129718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The presence of one or two apoliprotein E4 (apoE4) alleles constitutes a major risk factor for Alzheimer's disease (AD) and coronary heart disease (CHD). Numerous observations have suggested that misregulation of proteases may be instrumental in both diseases. Tissue-type plasminogen activator (tPA) has been recently demonstrated to play a key role in neuronal plasticity and in experimental neurodegeneration. One receptor for the ApoE protein is the LRP/alpha 2 macroglobulin receptor, which also binds to and endocytoses tPA and plasminogen activator inhibitor I (PAI-1). Here we tested whether the apoE genotype has an influence on the plasma levels of these proteins. We demonstrate that there is no difference in plasma levels of tPA- and PAI-1-antigens between middled-aged individuals with one apoE4 allele and those having none. This suggests that the impact of apoE4 on Alzheimer's disease is not the result of altered clearance of tPA or PAI-1 by the LRP receptor.
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Affiliation(s)
- J J Mermod
- Geneva Biomedical Research Institute, Glaxo Wellcome Research and Development, Switzerland
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44
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Allet B, Hochmann A, Martinou I, Berger A, Missotten M, Antonsson B, Sadoul R, Martinou JC, Bernasconi L. Dissecting processing and apoptotic activity of a cysteine protease by mutant analysis. J Cell Biol 1996; 135:479-86. [PMID: 8896603 PMCID: PMC2121040 DOI: 10.1083/jcb.135.2.479] [Citation(s) in RCA: 23] [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] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We have compared the behavior of wild-type mouse NEDD-2, a neural precursor cell-expressed, developmentally down-regulated cysteine protease gene, to various mutant forms of the gene in both apoptotic activity in neuronal cells and proteolytic cleavage in the Semliki Forest virus and rabbit reticulocyte protein expression systems. Our results confirm that NEDD-2 processing and apoptotic activity are linked phenomena. They identify aspartate residues as likely targets for autocatalytic cleavage. They establish that cleavage events only occur at specific sites. Finally, they pinpoint differential effects of individual mutations on the overall proteolytic cleavage patterns, raising interesting questions related to the mechanisms of subunit assembly.
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Affiliation(s)
- B Allet
- Geneva Biomedical Research Institute, Glaxo Wellcome Research and Development S.A., Switzerland
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45
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Abstract
The past year has witnessed significant advances in our understanding of the mechanisms that kill neurons during programmed cell death. The executioners are members of a family of proteases founded by ced-3, the product of a gene that is required for programmed cell death in the nematode Caenorhabditis elegans, and by mammalian interleukin-1 beta-converting enzyme. These proteases represent interesting novel targets for the therapy of acute and chronic pathologies of the nervous system associated with neuronal death.
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Affiliation(s)
- J C Martinou
- Geneva Biomedical Research Institute, Glaxo Wellcome Research and Development S.A, Switzerland.
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46
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Sadoul R, Fernandez PA, Quiquerez AL, Martinou I, Maki M, Schröter M, Becherer JD, Irmler M, Tschopp J, Martinou JC. Involvement of the proteasome in the programmed cell death of NGF-deprived sympathetic neurons. EMBO J 1996; 15:3845-52. [PMID: 8670889 PMCID: PMC452074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Sympathetic neurons undergo programmed cell death (PCD) upon deprivation of nerve growth factor (NGF). PCD of neurons is blocked by inhibitors of the interleukin-1beta converting enzyme (ICE)/Ced-3-like cysteine protease, indicating involvement of this class of proteases in the cell death programme. Here we demonstrate that the proteolytic activities of the proteasome are also essential in PCD of neurons. Nanomolar concentrations of several proteasome inhibitors, including the highly selective inhibitor lactacystin, not only prolonged survival of NGF-deprived neurons but also prevented processing of poly(ADP-ribose) polymerase which is known to be cleaved by an ICE/Ced-3 family member during PCD. These results demonstrate that the proteasome is a key regulator of neuronal PCD and that, within this process, it is involved upstream of proteases of the ICE/Ced-3 family. This order of events was confirmed in macrophages where lactacystin inhibited the proteolytic activation of precursor ICE and the subsequent generation of active interleukin-1beta.
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Affiliation(s)
- R Sadoul
- Geneva Biomedical Research Institute, 14 chemin des Aulx, 1228 Plan-Les-Ouates, Geneva, Switzerland
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47
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Abstract
The p53 tumour suppressor gene plays a major role in controlling cell cycle and apoptosis in many different cell types. Here we have examined the status and the potential apoptosis inducing activity of p53 in sympathetic neurons. The p53 protein is expressed in rat sympathetic neurons cultured in the presence of NGF. The protein is not upregulated when these neurons are induced to die upon NGF deprivation. Over-expression of wild-type human p53 in neurons cultured in the presence of NGF does not trigger apoptosis nor does it accelerate apoptosis when the neurons are deprived of NGF. Finally endogenous p53 expression is not necessary for neuronal cell death triggered by NGF deprivation since neurons prepared from p53 knockout mice undergo normal cell death upon NGF deprivation. Our results suggest that p53 may have an unknown function in post-mitotic neurons which is distinct from its well described roles in apoptosis or cell cycle control.
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Affiliation(s)
- R Sadoul
- Department of Neurobiology, Glaxo Institute for Molecular Biology, Geneva, Switzerland
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48
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Frankowski H, Missotten M, Fernandez PA, Martinou I, Michel P, Sadoul R, Martinou JC. Function and expression of the Bcl-x gene in the developing and adult nervous system. Neuroreport 1995; 6:1917-21. [PMID: 8547598 DOI: 10.1097/00001756-199510020-00023] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have shown that overexpression of Bcl-x can rescue sympathetic neurones from nerve growth factor deprivation in vitro. We have also examined the distribution and expression of Bcl-x mRNA in the developing and adult nervous system using Northern blot and in situ hybridization. Bcl-x mRNA is widespread during development of the nervous system. In embryonic spinal cord, mRNA levels increase at the beginning of the naturally occurring cell death period, suggesting that Bcl-x may be involved in the selection of neurones during this period. In the brain, Bcl-x expression increases after birth to reach a high level in the adult brain. Neurones from the cortex, olfactory bulb, and Purkinje cells are among those expressing the highest levels of Bcl-x mRNA. The widespread expression of Bcl-x during development and in adult brain suggests of a role for Bcl-x beyond simply protecting neurones from developmental cell death.
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Affiliation(s)
- H Frankowski
- Glaxo Institute for Molecular Biology, Geneva, Switzerland
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49
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Abstract
Apoptosis is critically dependent on the presence of the ced-3 gene in Caenorhabditis elegans, which encodes a protein homologous to the mammalian interleukin (IL)-1 beta-converting enzyme (ICE). Overexpression of ICE or ced-3 promotes apoptosis. Cytotoxic T lymphocyte-mediated rapid apoptosis is induced by the proteases granzyme A and B. ICE and granzyme B share the rare substrate site of aspartic acid, after which amino acid cleavage of precursor IL-1 beta (pIL-1 beta) occurs. Here we show that granzyme A, but not granzyme B, converts pIL-1 beta to its 17-kD mature form. Major cleavage occurs at Arg120, four amino acids downstream of the authentic processing site, Asp116. IL-1 beta generated by granzyme A is biologically active. When pIL-1 beta processing is monitored in lipopolysaccharide-activated macrophage target cells attacked by cytotoxic T lymphocytes, intracellular conversion precedes lysis. Prior granzyme inactivation blocks this processing. We conclude that the apoptosis-inducing granzyme A and ICE share at least one downstream target substrate, i.e., pIL-1 beta. This suggests that lymphocytes, by means of their own converting enzyme, could initiate a local inflammatory response independent of the presence of ICE.
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Affiliation(s)
- M Irmler
- Institute of Biochemistry, University of Lausanne, Epalinges, Switzerland
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50
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Martinou I, Fernandez PA, Missotten M, White E, Allet B, Sadoul R, Martinou JC. Viral proteins E1B19K and p35 protect sympathetic neurons from cell death induced by NGF deprivation. J Biophys Biochem Cytol 1995; 128:201-8. [PMID: 7822415 PMCID: PMC2120324 DOI: 10.1083/jcb.128.1.201] [Citation(s) in RCA: 113] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
To study molecular mechanisms underlying neuronal cell death, we have used sympathetic neurons from superior cervical ganglia which undergo programmed cell death when deprived of nerve growth factor. These neurons have been microinjected with expression vectors containing cDNAs encoding selected proteins to test their regulatory influence over cell death. Using this procedure, we have shown previously that sympathetic neurons can be protected from NGF deprivation by the protooncogene Bcl-2. We now report that the E1B19K protein from adenovirus and the p35 protein from baculovirus also rescue neurons. Other adenoviral proteins, E1A and E1B55K, have no effect on neuronal survival. E1B55K, known to block apoptosis mediated by p53 in proliferative cells, failed to rescue sympathetic neurons suggesting that p53 is not involved in neuronal death induced by NGF deprivation. E1B19K and p35 were also coinjected with Bcl-Xs which blocks Bcl-2 function in lymphoid cells. Although Bcl-Xs blocked the ability of Bcl-2 to rescue neurons, it had no effect on survival that was dependent upon expression of E1B19K or p35.
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Affiliation(s)
- I Martinou
- Glaxo Institute for Molecular Biology, Geneva, Switzerland
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