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Tanguy E, Wolf A, Montero-Hadjadje M, Gasman S, Bader MF, Vitale N. Phosphatidic acid: Mono- and poly-unsaturated forms regulate distinct stages of neuroendocrine exocytosis. Adv Biol Regul 2020; 79:100772. [PMID: 33288473 DOI: 10.1016/j.jbior.2020.100772] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 11/16/2020] [Accepted: 11/25/2020] [Indexed: 10/22/2022]
Abstract
Lipids have emerged as important actors in an ever-growing number of key functions in cell biology over the last few years. Among them, glycerophospholipids are major constituents of cellular membranes. Because of their amphiphilic nature, phospholipids form lipid bilayers that are particularly useful to isolate cellular content from the extracellular medium, but also to define intracellular compartments. Interestingly, phospholipids come in different flavors based on their fatty acyl chain composition. Indeed, lipidomic analyses have revealed the presence in cellular membranes of up to 50 different species of an individual class of phospholipid, opening the possibility of multiple functions for a single class of phospholipid. In this review we will focus on phosphatidic acid (PA), the simplest phospholipid, that plays both structural and signaling functions. Among the numerous roles that have been attributed to PA, a key regulatory role in secretion has been proposed in different cell models. We review here the evidences that support the idea that mono- and poly-unsaturated PA control distinct steps in hormone secretion from neuroendocrine cells.
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Affiliation(s)
- Emeline Tanguy
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France
| | - Alexander Wolf
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France
| | - Maité Montero-Hadjadje
- Normandie Univ, UNIROUEN, INSERM, U1239, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, 76000, Rouen, France
| | - Stéphane Gasman
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France
| | - Marie-France Bader
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France
| | - Nicolas Vitale
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France.
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Gabel M, Royer C, Thahouly T, Calco V, Gasman S, Bader MF, Vitale N, Chasserot-Golaz S. Annexin A2 Egress during Calcium-Regulated Exocytosis in Neuroendocrine Cells. Cells 2020; 9:cells9092059. [PMID: 32917016 PMCID: PMC7564067 DOI: 10.3390/cells9092059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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] [Received: 07/08/2020] [Revised: 09/04/2020] [Accepted: 09/06/2020] [Indexed: 02/08/2023] Open
Abstract
Annexin A2 (AnxA2) is a calcium- and lipid-binding protein involved in neuroendocrine secretion where it participates in the formation and/or stabilization of lipid micro-domains required for structural and spatial organization of the exocytotic machinery. We have recently described that phosphorylation of AnxA2 on Tyr23 is critical for exocytosis. Considering that Tyr23 phosphorylation is known to promote AnxA2 externalization to the outer face of the plasma membrane in different cell types, we examined whether this phenomenon occurred in neurosecretory chromaffin cells. Using immunolabeling and biochemical approaches, we observed that nicotine stimulation triggered the egress of AnxA2 to the external leaflets of the plasma membrane in the vicinity of exocytotic sites. AnxA2 was found co-localized with tissue plasminogen activator, previously described on the surface of chromaffin cells following secretory granule release. We propose that AnxA2 might be a cell surface tissue plasminogen activator receptor for chromaffin cells, thus playing a role in autocrine or paracrine regulation of exocytosis.
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Affiliation(s)
- Marion Gabel
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France; (M.G.); (T.T.); (V.C.); (S.G.); (M.-F.B.); (N.V.)
| | - Cathy Royer
- Plateforme Imagerie In Vitro, Neuropôle, Université de Strasbourg, F-67000 Strasbourg, France;
| | - Tamou Thahouly
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France; (M.G.); (T.T.); (V.C.); (S.G.); (M.-F.B.); (N.V.)
| | - Valérie Calco
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France; (M.G.); (T.T.); (V.C.); (S.G.); (M.-F.B.); (N.V.)
| | - Stéphane Gasman
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France; (M.G.); (T.T.); (V.C.); (S.G.); (M.-F.B.); (N.V.)
| | - Marie-France Bader
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France; (M.G.); (T.T.); (V.C.); (S.G.); (M.-F.B.); (N.V.)
| | - Nicolas Vitale
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France; (M.G.); (T.T.); (V.C.); (S.G.); (M.-F.B.); (N.V.)
| | - Sylvette Chasserot-Golaz
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000 Strasbourg, France; (M.G.); (T.T.); (V.C.); (S.G.); (M.-F.B.); (N.V.)
- Plateforme Imagerie In Vitro, Neuropôle, Université de Strasbourg, F-67000 Strasbourg, France;
- Correspondence: ; Tel.: +333-88-45-67-39
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3
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Baneux C, Tanguy E, Thahouly T, Vitale A, Chasserot-Golaz S, Bader MF, Gasman S, Vitale N. Phosphatidic acid metabolism regulates neuroendocrine secretion but is not under the direct control of lipins. IUBMB Life 2020; 72:533-543. [PMID: 31967386 DOI: 10.1002/iub.2229] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [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: 12/13/2019] [Accepted: 01/04/2020] [Indexed: 11/11/2022]
Abstract
Phosphatidic acid (PA) produced by phospholipase D1 has been shown to contribute to secretory vesicle exocytosis in a large number of cell models. Among various hypotheses, PA may contribute to recruit and/or activate at the exocytotic site a set of proteins from the molecular machinery dedicated to secretion, but also directly influence membrane curvature thereby favoring membrane rearrangements required for membrane fusion. The release of informative molecules by regulated exocytosis is a tightly controlled process. It is thus expected that PA produced to trigger membrane fusion should be rapidly metabolized and converted in a lipid that does not present similar characteristics. PA-phosphatases of the lipin family are possible candidates as they convert PA into diacylglycerol. We show here that lipin 1 and lipin 2 are expressed in neuroendocrine cells where they are cytosolic, but also partially associated with the endoplasmic reticulum. Silencing of lipin 1 or 2 did not affect significantly either basal or evoked secretion from PC12 cells, suggesting that it is unlikely that conversion of PA into a secondary lipid by lipins might represent a regulatory step in exocytosis in neurosecretory cells. However, in agreement with a model in which PA-metabolism could contribute to prevent entering into exocytosis of additional secretory vesicles, ectopic expression of lipin1B-GFP in bovine chromaffin cells reduced the number of exocytotic events as revealed by carbon fiber amperometry recording. Furthermore, individual spike parameters reflecting fusion pore dynamics were also modified by lipin1B-GFP, suggesting that a tight control of PA levels represents an important regulatory step of the number and kinetic of exocytotic events.
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Affiliation(s)
- Claire Baneux
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Emeline Tanguy
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Tamou Thahouly
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Alessio Vitale
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Sylvette Chasserot-Golaz
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Marie-France Bader
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Stéphane Gasman
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Nicolas Vitale
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
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Houy S, Nicolas G, Momboisse F, Malacombe M, Bader MF, Vitale N, Lecomte MC, Ory S, Gasman S. αII-spectrin controls calcium-regulated exocytosis in neuroendocrine chromaffin cells through neuronal Wiskott-Aldrich Syndrome protein interaction. IUBMB Life 2019; 72:544-552. [PMID: 31859439 DOI: 10.1002/iub.2217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 11/08/2019] [Accepted: 11/30/2019] [Indexed: 11/11/2022]
Abstract
Besides a fundamental structural role at the plasma membrane, spectrin- and actin-based skeletons have been proposed to participate in various processes including vesicular trafficking. Neuroendocrine cells release hormones and neuropeptides through calcium-regulated exocytosis, a process that is coordinated by a fine remodeling of the actin cytoskeleton. We describe here that calcium-regulated exocytosis is impaired in chromaffin and PC12 cells with reduced αII-spectrin expression levels. Using yeast two-hybrid screening, we show that neuronal Wiskott-Aldrich Syndrome protein (N-WASP) is a partner of the αII-spectrin SH3 domain and demonstrate that secretagogue-evoked N-WASP recruitment at cell periphery is blocked in the absence of αII-spectrin. Additionally, experiments performed with ectopically expressed αII-spectrin mutant unable to bind N-WASP indicated that the interaction between SH3 domain and N-WASP is pivotal for neuroendocrine secretion. Our results extend the list of spectrin interactors and strengthen the idea that αII-spectrin is an important scaffold protein that gathers crucial actin-related players of the exocytic machinery.
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Affiliation(s)
- Sébastien Houy
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| | - Gaël Nicolas
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l'inflammation, Université Paris Diderot, Paris, France.,Laboratory of Excellence GR-EX, Paris, France
| | - Fanny Momboisse
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| | - Magali Malacombe
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| | - Marie-France Bader
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| | - Nicolas Vitale
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| | - Marie-Christine Lecomte
- Laboratory of Excellence GR-EX, Paris, France.,Biologie Intégrée du Globule Rouge UMR_S1134, Inserm, Université Paris Diderot, Paris, France.,Institut National de la Transfusion Sanguine, Université des Antilles, Paris, France
| | - Stéphane Ory
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| | - Stéphane Gasman
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
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Gabel M, Delavoie F, Royer C, Tahouly T, Gasman S, Bader MF, Vitale N, Chasserot-Golaz S. Phosphorylation cycling of Annexin A2 Tyr23 is critical for calcium-regulated exocytosis in neuroendocrine cells. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 2019; 1866:1207-1217. [DOI: 10.1016/j.bbamcr.2018.12.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 12/21/2018] [Accepted: 12/22/2018] [Indexed: 10/27/2022]
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6
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Tanguy E, Tran Nguyen AP, Kassas N, Bader MF, Grant NJ, Vitale N. Regulation of Phospholipase D by Arf6 during FcγR-Mediated Phagocytosis. J I 2019; 202:2971-2981. [DOI: 10.4049/jimmunol.1801019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 03/11/2019] [Indexed: 12/20/2022]
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7
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Kassas N, Tanguy E, Thahouly T, Fouillen L, Heintz D, Chasserot-Golaz S, Bader MF, Grant NJ, Vitale N. Comparative Characterization of Phosphatidic Acid Sensors and Their Localization during Frustrated Phagocytosis. J Biol Chem 2017; 292:4266-4279. [PMID: 28115519 DOI: 10.1074/jbc.m116.742346] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [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: 12/12/2016] [Revised: 01/20/2017] [Indexed: 11/06/2022] Open
Abstract
Phosphatidic acid (PA) is the simplest phospholipid naturally existing in living organisms, but it constitutes only a minor fraction of total cell lipids. PA has attracted considerable attention because it is a phospholipid precursor, a lipid second messenger, and a modulator of membrane shape, and it has thus been proposed to play key cellular functions. The dynamics of PA in cells and in subcellular compartments, however, remains an open question. The recent generation of fluorescent probes for PA, by fusing GFP to PA-binding domains, has provided direct evidence for PA dynamics in different intracellular compartments. Here, three PA sensors were characterized in vitro, and their preferences for different PA species in particular lipidic environments were compared. In addition, the localization of PA in macrophages during frustrated phagocytosis was examined using these PA sensors and was combined with a lipidomic analysis of PA in intracellular compartments. The results indicate that the PA sensors display some preferences for specific PA species, depending on the lipid environment, and the localization study in macrophages revealed the complexity of intracellular PA dynamics.
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Affiliation(s)
- Nawal Kassas
- From the Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 CNRS and Université de Strasbourg, 5 Rue Blaise Pascal, 67084 Strasbourg
| | - Emeline Tanguy
- From the Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 CNRS and Université de Strasbourg, 5 Rue Blaise Pascal, 67084 Strasbourg
| | - Tamou Thahouly
- From the Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 CNRS and Université de Strasbourg, 5 Rue Blaise Pascal, 67084 Strasbourg
| | - Laetitia Fouillen
- the Laboratoire de Biogénèse Membranaire, UMR-5200 CNRS, Plateforme Métabolome, Université de Bordeaux, 33883 Villenave D'Ornon, and
| | - Dimitri Heintz
- the Plateforme Métabolomique, Institut de Biologie Moléculaire des Plantes, UPR-2357 CNRS and Université de Strasbourg, Institut de Botanique, 28 Rue Goethe, 67083 Strasbourg, France
| | - Sylvette Chasserot-Golaz
- From the Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 CNRS and Université de Strasbourg, 5 Rue Blaise Pascal, 67084 Strasbourg
| | - Marie-France Bader
- From the Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 CNRS and Université de Strasbourg, 5 Rue Blaise Pascal, 67084 Strasbourg
| | - Nancy J Grant
- From the Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 CNRS and Université de Strasbourg, 5 Rue Blaise Pascal, 67084 Strasbourg
| | - Nicolas Vitale
- From the Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 CNRS and Université de Strasbourg, 5 Rue Blaise Pascal, 67084 Strasbourg,
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Gabel M, Delavoie F, Vitale N, Bader MF, Chasserot-Golaz S. [Actin and annexin A2: essential partners for the control of neuroendocrine secretion]. Med Sci (Paris) 2016; 32:553-5. [PMID: 27406755 DOI: 10.1051/medsci/20163206008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Marion Gabel
- Institut des neurosciences cellulaires et intégratives, CNRS - UPR 3212 et université de Strasbourg, 5, rue Blaise Pascal, F-67084, Strasbourg, France
| | - Franck Delavoie
- Laboratoire de biologie moléculaire eucaryote, UMR5099 CNRS-université de Toulouse III Paul Sabatier, 118, route de Narbonne, F-31000, Toulouse, France
| | - Nicolas Vitale
- Institut des neurosciences cellulaires et intégratives, CNRS - UPR 3212 et université de Strasbourg, 5, rue Blaise Pascal, F-67084, Strasbourg, France
| | - Marie-France Bader
- Institut des neurosciences cellulaires et intégratives, CNRS - UPR 3212 et université de Strasbourg, 5, rue Blaise Pascal, F-67084, Strasbourg, France
| | - Sylvette Chasserot-Golaz
- Institut des neurosciences cellulaires et intégratives, CNRS - UPR 3212 et université de Strasbourg, 5, rue Blaise Pascal, F-67084, Strasbourg, France
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Gabel M, Delavoie F, Demais V, Royer C, Bailly Y, Vitale N, Bader MF, Chasserot-Golaz S. Annexin A2-dependent actin bundling promotes secretory granule docking to the plasma membrane and exocytosis. J Cell Biol 2015; 210:785-800. [PMID: 26323692 PMCID: PMC4555831 DOI: 10.1083/jcb.201412030] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Annexin A2, a calcium-, actin-, and lipid-binding protein involved in exocytosis, mediates the formation of lipid microdomains required for the structural and spatial organization of fusion sites at the plasma membrane. To understand how annexin A2 promotes this membrane remodeling, the involvement of cortical actin filaments in lipid domain organization was investigated. 3D electron tomography showed that cortical actin bundled by annexin A2 connected docked secretory granules to the plasma membrane and contributed to the formation of GM1-enriched lipid microdomains at the exocytotic sites in chromaffin cells. When an annexin A2 mutant with impaired actin filament-bundling activity was expressed, the formation of plasma membrane lipid microdomains and the number of exocytotic events were decreased and the fusion kinetics were slower, whereas the pharmacological activation of the intrinsic actin-bundling activity of endogenous annexin A2 had the opposite effects. Thus, annexin A2-induced actin bundling is apparently essential for generating active exocytotic sites.
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Affiliation(s)
- Marion Gabel
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 Centre National de la Recherche Scientifique, Université de Strasbourg, F-67084 Strasbourg, France
| | - Franck Delavoie
- Laboratoire de Biologie Moléculaire Eucaryote, UMR5099 Centre National de la Recherche Scientifique-Université de Toulouse III Paul Sabatier, F-31000 Toulouse, France
| | - Valérie Demais
- Plateforme Imagerie In Vitro, Neuropôle de Strasbourg, F-67084 Strasbourg, France
| | - Cathy Royer
- Plateforme Imagerie In Vitro, Neuropôle de Strasbourg, F-67084 Strasbourg, France
| | - Yannick Bailly
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 Centre National de la Recherche Scientifique, Université de Strasbourg, F-67084 Strasbourg, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 Centre National de la Recherche Scientifique, Université de Strasbourg, F-67084 Strasbourg, France
| | - Marie-France Bader
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 Centre National de la Recherche Scientifique, Université de Strasbourg, F-67084 Strasbourg, France
| | - Sylvette Chasserot-Golaz
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 Centre National de la Recherche Scientifique, Université de Strasbourg, F-67084 Strasbourg, France
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10
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Gabel M, Delavoie F, Demais V, Royer C, Bailly Y, Vitale N, Bader MF, Chasserot-Golaz S. Annexin A2–dependent actin bundling promotes secretory granule docking to the plasma membrane and exocytosis. J Gen Physiol 2015. [DOI: 10.1085/jgp.1463oia51] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Ammar MR, Kassas N, Bader MF, Vitale N. Phosphatidic acid in neuronal development: A node for membrane and cytoskeleton rearrangements. Biochimie 2014; 107 Pt A:51-7. [DOI: 10.1016/j.biochi.2014.07.026] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 07/30/2014] [Indexed: 12/22/2022]
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12
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Tryoen-Tóth P, Beaumelle B, Bader MF, Vitale N. [HIV-associated cognitive disorders: tat perturbs neurosecretion]. Med Sci (Paris) 2013; 29:1069-70. [PMID: 24356129 DOI: 10.1051/medsci/20132912002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Petra Tryoen-Tóth
- Institut des neurosciences cellulaires et intégratives ; CNRS UPR-3212, 5, rue Blaise Pascal, 67084 Strasbourg ; Université de Strasbourg, Strasbourg, France
| | - Bruno Beaumelle
- CPBS - Centre d'étude d'agents pathogènes et biotechnologies pour la santé ; UMR 5236 CNRS ; Université Montpellier 1 et 2 ; 1919, route de Mende, 34293 Montpellier Cedex 5, France
| | - Marie-France Bader
- Institut des neurosciences cellulaires et intégratives ; CNRS UPR-3212, 5, rue Blaise Pascal, 67084 Strasbourg ; Université de Strasbourg, Strasbourg, France
| | - Nicolas Vitale
- Institut des neurosciences cellulaires et intégratives ; CNRS UPR-3212, 5, rue Blaise Pascal, 67084 Strasbourg ; Université de Strasbourg, Strasbourg, France
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13
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Houy S, Croisé P, Gubar O, Chasserot-Golaz S, Tryoen-Tóth P, Bailly Y, Ory S, Bader MF, Gasman S. Exocytosis and endocytosis in neuroendocrine cells: inseparable membranes! Front Endocrinol (Lausanne) 2013; 4:135. [PMID: 24106488 PMCID: PMC3788349 DOI: 10.3389/fendo.2013.00135] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 09/13/2013] [Indexed: 12/23/2022] Open
Abstract
Although much has been learned concerning the mechanisms of secretory vesicle formation and fusion at donor and acceptor membrane compartments, relatively little attention has been paid toward understanding how cells maintain a homeostatic membrane balance through vesicular trafficking. In neurons and neuroendocrine cells, release of neurotransmitters, neuropeptides, and hormones occurs through calcium-regulated exocytosis at the plasma membrane. To allow recycling of secretory vesicle components and to preserve organelles integrity, cells must initiate and regulate compensatory membrane uptake. This review relates the fate of secretory granule membranes after full fusion exocytosis in neuroendocrine cells. In particular, we focus on the potential role of lipids in preserving and sorting secretory granule membranes after exocytosis and we discuss the potential mechanisms of membrane retrieval.
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Affiliation(s)
- Sébastien Houy
- Institut des Neurosciences Cellulaires et Intégratives (INCI), Centre National de la Recherche Scientifique (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Pauline Croisé
- Institut des Neurosciences Cellulaires et Intégratives (INCI), Centre National de la Recherche Scientifique (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Olga Gubar
- Institut des Neurosciences Cellulaires et Intégratives (INCI), Centre National de la Recherche Scientifique (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Sylvette Chasserot-Golaz
- Institut des Neurosciences Cellulaires et Intégratives (INCI), Centre National de la Recherche Scientifique (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Petra Tryoen-Tóth
- Institut des Neurosciences Cellulaires et Intégratives (INCI), Centre National de la Recherche Scientifique (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Yannick Bailly
- Institut des Neurosciences Cellulaires et Intégratives (INCI), Centre National de la Recherche Scientifique (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Stéphane Ory
- Institut des Neurosciences Cellulaires et Intégratives (INCI), Centre National de la Recherche Scientifique (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Marie-France Bader
- Institut des Neurosciences Cellulaires et Intégratives (INCI), Centre National de la Recherche Scientifique (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Stéphane Gasman
- Institut des Neurosciences Cellulaires et Intégratives (INCI), Centre National de la Recherche Scientifique (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
- *Correspondence: Stéphane Gasman, Institut des Neurosciences Cellulaires et Intégratives (INCI), Centre National de la Recherche Scientifique (CNRS UPR 3212), Université de Strasbourg, 5 rue Blaise Pascal, Strasbourg 67084, France e-mail:
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14
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Abstract
The regulated secretory pathway in neuroendocrine cells ends with the release of hormones and neurotransmitters following a rise in cytosolic calcium. This process known as regulated exocytosis involves the assembly of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins, the synaptic vesicle VAMP (synaptobrevin), and the plasma membrane proteins syntaxin and SNAP-25. Although there is much evidence suggesting that SNARE proteins play a key role in the fusion machinery, other cellular elements regulating the kinetics, the extent of fusion, and the preparation of vesicle for release have received less attention. Among those factors, lipids have also been proposed to play important functions both at the level of secretory vesicle recruitment and late membrane fusion steps. Here, we will review the latest evidence supporting the concept of the fusogenic activity of lipids, and also discuss how this may be achieved. These possibilities include the recruitment and sequestration of the components of the exocytotic machinery, regulation of protein function, and direct effects on membrane topology.
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Affiliation(s)
- Mohamed Raafet Ammar
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Nawal Kassas
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Sylvette Chasserot-Golaz
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Marie-France Bader
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
- *Correspondence: Nicolas Vitale, Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique, Université de Strasbourg, 5 rue Blaise Pascal, 67084 Strasbourg, France e-mail:
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15
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Vitale N, Beaumelle B, Bader MF, Tryoen-Tóth P. HIV-1 Tat protein perturbs diacylglycerol production at the plasma membrane of neurosecretory cells during exocytosis. Commun Integr Biol 2013; 6:e25145. [PMID: 24255740 PMCID: PMC3829902 DOI: 10.4161/cib.25145] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 05/22/2013] [Accepted: 05/22/2013] [Indexed: 11/21/2022] Open
Abstract
Human immunodeficiency virus (HIV)-infected cells actively release the transcriptional activator (Tat) viral protein that is required for efficient HIV gene transcription. We recently reported that extracellular Tat is able to enter uninfected neurosecretory cells. Internalized Tat escapes endosomes to reach the cytosol and is then recruited to the plasma membrane by phosphatidylinositol 4,5-bisphophate (PtdIns(4,5)P2). Tat strongly impairs exocytosis from chromaffin and PC12 cells and perturbs synaptic vesicle exo-endocytosis cycle through its ability to interact with PtdIns(4,5)P2. Among PtdIns(4,5)P2-dependent processes required for neurosecretion, we found that Tat impairs annexin A2 recruitment involved in the organization of exocytotic sites at the plasma membrane. Moreover Tat perturbs the actin cytoskeleton reorganization necessary for the movement of secretory vesicles toward their plasma membrane fusion sites during the exocytotic process.
Here, we investigated whether extracellular Tat affects PtdIns(4,5)P2 metabolism in PC12 cells. Using a diacylglycerol (DAG) sensor, we found that ATP stimulation of exocytosis triggers the production of DAG at the plasma membrane as seen by the relocation of the DAG probe from the cytosol to the plasma membrane. Exposure to Tat strongly delayed the recruitment of the DAG sensor, suggesting a reduced level of DAG production at the early phase of ATP stimulation. These observations indicate that Tat reduces the hydrolysis rate of PtdIns(4,5)P2 by phospholipase C during exocytosis. Thus, the neuronal disorders often associated with HIV-1 infection may be linked to the capacity of Tat to interact with PtdIns(4,5)P2, and alter both its metabolism and functions in neurosecretion.
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Affiliation(s)
- Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives; CNRS UPR3212; Université de Strasbourg; Strasbourg, France
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16
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Tryoen-Tóth P, Chasserot-Golaz S, Tu A, Gherib P, Bader MF, Beaumelle B, Vitale N. HIV-1 Tat protein inhibits neurosecretion by binding to phosphatidylinositol (4,5) bisphosphate. J Cell Sci 2012. [DOI: 10.1242/jcs.111658] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
HIV-1 Tat enables viral transcription and is also actively released by infected cells. Extracellular Tat can enter uninfected cells and affect some cellular functions. Here, we examine the effects of Tat protein on the secretory activity of neuroendocrine cells. When added to the culture medium of chromaffin and PC12 cells, Tat was actively internalized and strongly impaired exocytosis as measured by carbon fiber amperometry and growth hormone (GH) release assay. Expression of Tat mutants that do not bind to phosphatidylinositol-(4,5)-bisphophate (PI(4,5)P2) did not affect secretion, and overexpression of phosphatidylinositol 4 phosphate 5-kinase (PIP5K), the major PI(4,5)P2 synthesizing enzyme, significantly rescued the Tat-induced inhibition of neurosecretion. This suggests that the inhibition of exocytosis may be the consequence of PI(4,5)P2 sequestration. Accordingly expression of Tat in PC12 cells interfered with the secretagogue-dependent recruitment of annexin A2 to the plasma membrane, a PI(4,5)P2-binding protein that promotes the formation of lipid microdomains that are required for exocytosis. In addition Tat significantly prevented the reorganization of the actin cytoskeleton necessary for the movement of secretory vesicles towards plasma membrane fusion sites. Thus, the capacity of extracellular Tat to enter neuroendocrine cells and sequester plasma membrane PI(4,5)P2 perturbs several PI(4,5)P2-dependent players of the exocytotic machinery, thereby affecting neurosecretion. We propose that Tat-induced inhibition of exocytosis is involved in the neuronal disorders associated with HIV-1 infection.
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17
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Abstract
In addition to forming bilayers to separate cellular compartments, lipids participate in vesicular trafficking and signal transduction. Among others, phosphatidic acid (PA) is emerging as an important signaling molecule. The spatiotemporal distribution of cellular PA appears to be tightly regulated by localized synthesis and a rapid metabolism. Although PA has been long proposed as a pleiotropic bioactive lipid, when and where PA is produced in the living cells have only recently been explored using biosensors that specifically bind to PA. The probes that we have generated are composed of the PA-binding domains of either Spo20p or Raf1 directly fused to GFP. In this chapter, we will describe the expression and purification of GST-fusion proteins of these probes, and the use of phospholipid strips to validate the specificity of their interaction with PA. We will then illustrate the use of GFP-tagged probes to visualize the synthesis of PA in the neurosecretory PC12 cells and RAW 267.4 macrophages. Interestingly, the two probes show a differential distribution in these cell types, indicating that they may have different affinities for PA or recognize different pools of PA. In conclusion, the development of a broader choice of probes may be required to adequately follow the complex dynamics of PA in different cell types, in order to determine the cellular distribution of PA and its role in various cellular processes.
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Affiliation(s)
- Nawal Kassas
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR3212, Strasbourg, France
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18
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Abstract
Rho GTPases are small GTP binding proteins belonging to the Ras superfamily which act as molecular switches that regulate many cellular function including cell morphology, cell to cell interaction, cell migration and adhesion. In neuronal cells, Rho GTPases have been proposed to regulate neuronal development and synaptic plasticity. However, the role of Rho GTPases in neurosecretion is poorly documented. In this review, we discuss data that highlight the importance of Rho GTPases and their regulators into the control of neurotransmitter and hormone release in neurons and neuroendocrine cells, respectively.
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Affiliation(s)
- Fanny Momboisse
- CNRS UPR 3212, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
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Ceridono M, Ory S, Momboisse F, Chasserot-Golaz S, Houy S, Calco V, Haeberlé AM, Demais V, Bailly Y, Bader MF, Gasman S. Selective Recapture of Secretory Granule Components After Full Collapse Exocytosis in Neuroendocrine Chromaffin Cells. Traffic 2010; 12:72-88. [DOI: 10.1111/j.1600-0854.2010.01125.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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20
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Corrotte M, Nyguyen APT, Harlay ML, Vitale N, Bader MF, Grant NJ. Ral isoforms are implicated in Fc gamma R-mediated phagocytosis: activation of phospholipase D by RalA. J Immunol 2010; 185:2942-50. [PMID: 20679536 DOI: 10.4049/jimmunol.0903138] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phagocytosis is an essential element of the immune response permitting the elimination of pathogens, cellular debris, apoptotic cells, and tumor cells. Recently, both phospholipase D (PLD) isoforms, PLD1 and PLD2, were shown to be necessary for efficient FcgammaR-mediated phagocytosis. In this study, we investigated the role of a potential PLD regulator, the Ral GTPases RalA and RalB, in murine RAW 264.7 macrophages. Both Ral isoforms are expressed in macrophages and are transiently activated following FcgammaR stimulation. When Ral expression levels were varied using Ral mutants or interference RNA, phagocytosis assays revealed that Ral isoforms have antagonistic effects; RalA is a positive modulator, whereas RalB plays a negative role. We then focused on RalA and its possible relationship with PLD. The increase in PLD activity that occurs when phagocytosis is stimulated was inhibited in cells with reduced RalA protein, but it was unaffected by reduced levels of RalB. Furthermore, in macrophages transfected with dsRed-RalA and GFP-PLD1 or GFP-PLD2, RalA colocalized with PLD1 and PLD2 at the phagocytic cup during phagosome formation. Additional results obtained from immunoprecipitation of PLD from macrophages transfected with myc-RalA and hemagglutinin-tagged PLD1 or PLD2 indicated an enhanced interaction of RalA with both PLD isoforms during phagocytic stimulation. The increase in RalA and PLD1 interaction was transient and correlated with the time course of RalA activation. These findings reveal a novel pathway involving RalA and PLD in the regulation of FcgammaR-mediated phagocytosis.
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Affiliation(s)
- Matthias Corrotte
- Département Neurotransmission et Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Unité Propre de Recherche 3212, Strasbourg, France
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21
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Umbrecht-Jenck E, Demais V, Calco V, Bailly Y, Bader MF, Chasserot-Golaz S. S100A10-mediated translocation of annexin-A2 to SNARE proteins in adrenergic chromaffin cells undergoing exocytosis. Traffic 2010; 11:958-71. [PMID: 20374557 DOI: 10.1111/j.1600-0854.2010.01065.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In neuroendocrine cells, annexin-A2 is implicated as a promoter of monosialotetrahexosylganglioside (GM1)-containing lipid microdomains that are required for calcium-regulated exocytosis. As soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) require a specific lipid environment to mediate granule docking and fusion, we investigated whether annexin-A2-induced lipid microdomains might be linked to the SNAREs present at the plasma membrane. Stimulation of adrenergic chromaffin cells induces the translocation of cytosolic annexin-A2 to the plasma membrane, where it colocalizes with SNAP-25 and S100A10. Cross-linking experiments performed in stimulated chromaffin cells indicate that annexin-A2 directly interacts with S100A10 to form a tetramer at the plasma membrane. Here, we demonstrate that S100A10 can interact with vesicle-associated membrane protein 2 (VAMP2) and show that VAMP2 is present at the plasma membrane in resting adrenergic chromaffin cells. Tetanus toxin that cleaves VAMP2 solubilizes S100A10 from the plasma membrane and inhibits the translocation of annexin-A2 to the plasma membrane. Immunogold labelling of plasma membrane sheets combined with spatial point pattern analysis confirmed that S100A10 is present in VAMP2 microdomains at the plasma membrane and that annexin-A2 is observed close to S100A10 and to syntaxin in stimulated chromaffin cells. In addition, these results showed that the formation of phosphatidylinositol (4,5)-bisphosphate (PIP(2)) microdomains colocalized with S100A10 in the vicinity of docked granules, suggesting a functional interplay between annexin-A2-mediated lipid microdomains and SNAREs during exocytosis.
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Affiliation(s)
- Emeline Umbrecht-Jenck
- Institut des Neurosciences Cellulaires et Intégratives, UPR 3212 CNRS, Université de Strasbourg, 5 rue Blaise Pascal, F-67084 Strasbourg, France
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22
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Vitale N, Thiersé D, Bader MF. Melittin promotes exocytosis in neuroendocrine cells through the activation of phospholipase A₂. ACTA ACUST UNITED AC 2009; 165:111-6. [PMID: 19800928 DOI: 10.1016/j.regpep.2009.09.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Revised: 09/17/2009] [Accepted: 09/24/2009] [Indexed: 01/02/2023]
Abstract
Regulated exocytosis requires the formation of trans-SNARE complexes that assemble at the interface between vesicles and the plasma membrane. Recent evidence has also highlighted the importance of lipid dynamic in this process. For instance, small cone-shaped lipids generating membrane curvature of the plasma membrane are synthesized at the exocytotic sites. Among those lipids, phosphatidic acid (PA) synthesized through the activity of phospholipase D (PLD) has been recently shown to be necessary to hormonal release in various cell types as well as in neurotransmitter release. In this paper we examined the possible role of arachidonic acid (AA), a fatty acid that is generated by the activity of phospholipase A₂ (PLA₂). Melittin a well-known activator of PLA₂ was found to concomitantly promote catecholamine and chromogranin A (CGA) release in a calcium-dependent manner and also to increase AA synthesis in chromaffin cells. The effects of melittin on exocytosis and AA synthesis did not involve heterotrimeric G protein activation, but were suppressed by PLA₂ inhibitors. Accordingly addition of exogenous PLA₂ stimulated AA synthesis and catecholamine release in permeabilized chromaffin cells, whereas provision of exogenous AA directly increased exocytosis. These results suggest that AA produced by PLA₂ activation during exocytosis may play an important regulatory role in hormonal and neurotransmitter release. The possibility that CGA-derived peptides released during exocytosis mimic the activity of melittin is discussed.
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Affiliation(s)
- Nicolas Vitale
- Département Neurotransmission & Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UPR-3212), Centre National de la Recherche Scientifique & Université de Strasbourg, 5 Rue Blaise Pascal, 67084 Strasbourg, France.
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23
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Bader MF, Vitale N. Phospholipase D in calcium-regulated exocytosis: Lessons from chromaffin cells. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:936-41. [DOI: 10.1016/j.bbalip.2009.02.016] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2008] [Revised: 02/23/2009] [Accepted: 02/26/2009] [Indexed: 10/21/2022]
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Momboisse F, Lonchamp E, Calco V, Ceridono M, Vitale N, Bader MF, Gasman S. betaPIX-activated Rac1 stimulates the activation of phospholipase D, which is associated with exocytosis in neuroendocrine cells. J Cell Sci 2009; 122:798-806. [PMID: 19261846 DOI: 10.1242/jcs.038109] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rho GTPases are crucial regulators of actin cytoskeletal rearrangements and play important roles in many cell functions linked to membrane trafficking processes. In neuroendocrine cells, we have previously demonstrated that RhoA and Cdc42 mediate part of the actin remodelling and vesicular trafficking events that are required for the release of hormones by exocytosis. Here, we investigate the functional importance of Rac1 for the exocytotic reaction and dissect the downstream and upstream molecular events that might integrate it to the exocytotic machinery. Using PC12 cells, we found that Rac1 is associated with the plasma membrane and is activated during exocytosis. Silencing of Rac1 by siRNA inhibits hormone release, prevents secretagogue (high K(+))-evoked phospholipase D1 (PLD1) activation and blocks the formation of phosphatidic acid at the plasma membrane. We identify betaPix as the guanine nucleotide-exchange factor integrating Rac1 activation to PLD1 and the exocytotic process. Finally, we show that the presence of the scaffolding protein Scrib at the plasma membrane is essential for betaPix/Rac1-mediated PLD1 activation and exocytosis. As PLD1 has recently emerged as a promoter of membrane fusion in various exocytotic events, our results define a novel molecular pathway linking a Rho GTPase, Rac1, to the final stages of Ca(2+)-regulated exocytosis in neuroendocrine cells.
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Affiliation(s)
- Fanny Momboisse
- Département Neurotransmission et Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Centre National de la Recherche Scientifique et Université de Strasbourg, 5 rue Blaise Pascal, 67084 Strasbourg, France
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25
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Zeniou-Meyer M, Béglé A, Bader MF, Vitale N. The Coffin-Lowry Syndrome-associated Protein RSK2 Controls Neuroendocrine Secretion through the Regulation of Phospholipase D1 at the Exocytotic Sites. Ann N Y Acad Sci 2009; 1152:201-8. [DOI: 10.1111/j.1749-6632.2008.04001.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Momboisse F, Ory S, Calco V, Malacombe M, Bader MF, Gasman S. Calcium-regulated Exocytosis in Neuroendocrine Cells: Intersectin-1L Stimulates Actin Polymerization and Exocytosis by Activating Cdc42. Ann N Y Acad Sci 2009; 1152:209-14. [DOI: 10.1111/j.1749-6632.2008.03998.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Béglé A, Tryoen-Tóth P, de Barry J, Bader MF, Vitale N. ARF6 regulates the synthesis of fusogenic lipids for calcium-regulated exocytosis in neuroendocrine cells. J Biol Chem 2009; 284:4836-45. [PMID: 19124467 DOI: 10.1074/jbc.m806894200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
An important role for specific lipids in membrane fusion has recently emerged, but regulation of their biosynthesis remains poorly understood. Among fusogenic lipids, phosphatidic acid and phosphoinositol 4,5-bisphosphate (PIP(2)) have been proposed to act at various steps of neurotransmitter and hormone exocytosis. Using real time FRET (fluorescence resonance energy transfer) measurements, we show here that the GTPase ARF6, potentially involved in the synthesis of these lipids, is activated at the exocytotic sites in PC12 cells stimulated for secretion. Depletion of endogenous ARF6 by siRNA dramatically inhibited secretagogue-evoked exocytosis. ARF6-siRNA greatly reduced secretagogue-evoked phospholipase D (PLD) activation and phosphatidic acid formation at the plasma membrane and moderately reduced constitutive levels of PIP(2) present at the plasma membrane in resting cells. Expression of an ARF6 insensitive to short interference RNA (siRNA) fully rescued secretion in ARF6-depleted cells. However, a mutated ARF6 protein specifically impaired in its ability to stimulate PLD had no effect. Finally, we show that the ARF6-siRNA-mediated inhibition of exocytosis could be rescued by an exogenous addition of lysophosphatidylcholine, a lipid that favors negative curvature on the inner leaflet of the plasma membrane. Altogether these data indicate that ARF6 is a critical upstream signaling element in the activation of PLD necessary to produce the fusogenic lipids required for exocytosis.
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Affiliation(s)
- Aurélie Béglé
- Département Neurotransmission et Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Centre National de la Recherche Scientifique et Université de Strasbourg, 5 rue Blaise Pascal, 67084 Strasbourg, France
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28
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Zeniou-Meyer M, Zabari N, Ashery U, Chasserot-Golaz S, Haeberlé AM, Demais V, Bailly Y, Gottfried I, Nakanishi H, Neiman AM, Du G, Frohman MA, Bader MF, Vitale N. Phospholipase D1 Production of Phosphatidic Acid at the Plasma Membrane Promotes Exocytosis of Large Dense-core Granules at a Late Stage. J Biol Chem 2007; 282:21746-57. [PMID: 17540765 DOI: 10.1074/jbc.m702968200] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Substantial efforts have recently been made to demonstrate the importance of lipids and lipid-modifying enzymes in various membrane trafficking processes, including calcium-regulated exocytosis of hormones and neurotransmitters. Among bioactive lipids, phosphatidic acid (PA) is an attractive candidate to promote membrane fusion through its ability to change membrane topology. To date, however, the biosynthetic pathway, the dynamic location, and actual function of PA in secretory cells remain unknown. Using a short interference RNA strategy on chromaffin and PC12 cells, we demonstrate here that phospholipase D1 is activated in secretagogue-stimulated cells and that it produces PA at the plasma membrane at the secretory granule docking sites. We show that phospholipase D1 activation and PA production represent key events in the exocytotic progression. Membrane capacitance measurements indicate that reduction of endogenous PA impairs the formation of fusion-competent granules. Finally, we show that the PLD1 short interference RNA-mediated inhibition of exocytosis can be rescued by exogenous provision of a lipid that favors the transition of opposed bi-layer membranes to hemifused membranes having the outer leaflets fused. Our findings demonstrate that PA synthesis is required during exocytosis to facilitate a late event in the granule fusion pathway. We propose that the underlying mechanism is related to the ability of PA to alter membrane curvature and promote hemi-fusion.
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Affiliation(s)
- Maria Zeniou-Meyer
- Département Neurotransmission & Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives, CNRS and Université Louis Pasteur, 5 rue Blaise Pascal, Strasbourg, France
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29
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Malacombe M, Bader MF, Gasman S. Exocytosis in neuroendocrine cells: new tasks for actin. Biochim Biophys Acta 2006; 1763:1175-83. [PMID: 17034880 DOI: 10.1016/j.bbamcr.2006.09.004] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 08/29/2006] [Accepted: 09/01/2006] [Indexed: 11/19/2022]
Abstract
Most secretory cells undergoing calcium-regulated exocytosis in response to cell surface receptor stimulation display a dense subplasmalemmal actin network, which is remodeled during the exocytotic process. This review summarizes new insights into the role of the cortical actin cytoskeleton in exocytosis. Many earlier findings support the actin-physical-barrier model whereby transient depolymerization of cortical actin filaments permits vesicles to gain access to their appropriate docking and fusion sites at the plasma membrane. On the other hand, data from our laboratory and others now indicate that actin polymerization also plays a positive role in the exocytotic process. Here, we discuss the potential functions attributed to the actin cytoskeleton at each major step of the exocytotic process, including recruitment, docking and fusion of secretory granules with the plasma membrane. Moreover, we present actin-binding proteins, which are likely to link actin organization to calcium signals along the exocytotic pathway. The results cited in this review are derived primarily from investigations of the adrenal medullary chromaffin cell, a cell model that is since many years a source of information concerning the molecular machinery underlying exocytosis.
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Affiliation(s)
- Magali Malacombe
- Département Neurotransmission et Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UMR 7168/LC2), Centre National de la Recherche Scientifique et Université Louis Pasteur, 5 rue Blaise Pascal, 67084 Strasbourg, France
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Malacombe M, Ceridono M, Calco V, Chasserot-Golaz S, McPherson PS, Bader MF, Gasman S. Intersectin-1L nucleotide exchange factor regulates secretory granule exocytosis by activating Cdc42. EMBO J 2006; 25:3494-503. [PMID: 16874303 PMCID: PMC1538555 DOI: 10.1038/sj.emboj.7601247] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Accepted: 06/29/2006] [Indexed: 11/09/2022] Open
Abstract
Rho GTPases are key regulators of the actin cytoskeleton in membrane trafficking events. We previously reported that Cdc42 facilitates exocytosis in neuroendocrine cells by stimulating actin assembly at docking sites for secretory granules. These findings raise the question of the mechanism activating Cdc42 in exocytosis. The neuronal guanine nucleotide exchange factor, intersectin-1L, which specifically activates Cdc42 and is at an interface between membrane trafficking and actin dynamics, appears as an ideal candidate to fulfill this function. Using PC12 and chromaffin cells, we now show the presence of intersectin-1 at exocytotic sites. Moreover, through an RNA interference strategy coupled with expression of various constructs encoding the guanine nucleotide exchange domain, we demonstrate that intersectin-1L is an essential component of the exocytotic machinery. Silencing of intersectin-1 prevents secretagogue-induced activation of Cdc42 revealing intersectin-1L as the factor integrating Cdc42 activation to the exocytotic pathway. Our results extend the current role of intersectin-1L in endocytosis to a function in exocytosis and support the idea that intersectin-1L is an adaptor that coordinates exo-endocytotic membrane trafficking in secretory cells.
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Affiliation(s)
- Magali Malacombe
- Département Neurotransmission & Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UMR 7168/LC2), Centre National de la Recherche Scientifique & Université Louis Pasteur, Strasbourg, France
| | - Mara Ceridono
- Département Neurotransmission & Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UMR 7168/LC2), Centre National de la Recherche Scientifique & Université Louis Pasteur, Strasbourg, France
| | - Valérie Calco
- Département Neurotransmission & Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UMR 7168/LC2), Centre National de la Recherche Scientifique & Université Louis Pasteur, Strasbourg, France
| | - Sylvette Chasserot-Golaz
- Département Neurotransmission & Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UMR 7168/LC2), Centre National de la Recherche Scientifique & Université Louis Pasteur, Strasbourg, France
| | - Peter S McPherson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Marie-France Bader
- Département Neurotransmission & Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UMR 7168/LC2), Centre National de la Recherche Scientifique & Université Louis Pasteur, Strasbourg, France
| | - Stéphane Gasman
- Département Neurotransmission & Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UMR 7168/LC2), Centre National de la Recherche Scientifique & Université Louis Pasteur, Strasbourg, France
- Département Neurotransmission & Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UMR 7168/LC2), Centre National de la Recherche Scientifique & Université Louis Pasteur, 5 rue Blaise Pascal, 67084 Strasbourg, France. Tel.: +33 388456712; Fax: +33 388601664; E-mail:
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Corrotte M, Chasserot-Golaz S, Huang P, Du G, Ktistakis NT, Frohman MA, Vitale N, Bader MF, Grant NJ. Dynamics and function of phospholipase D and phosphatidic acid during phagocytosis. Traffic 2006; 7:365-77. [PMID: 16497229 DOI: 10.1111/j.1600-0854.2006.00389.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Phospholipase D (PLD) produces phosphatidic acid (PA), an established intracellular signalling lipid that has been also implicated in vesicular trafficking, and as such, PLD could play multiple roles during phagocytosis. Using an RNA interference strategy, we show that endogenous PLD1 and PLD2 are necessary for efficient phagocytosis in murine macrophages, in line with results obtained with wild-type constructs and catalytically inactive PLD mutants which, respectively, enhance and inhibit phagocytosis. Furthermore, we found that PA is transiently produced at sites of phagosome formation. Macrophage PLD1 and PLD2 differ in their subcellular distributions. PLD1 is associated with cytoplasmic vesicles, identified as a late endosomal/lysosomal compartment, whereas PLD2 localizes at the plasma membrane. In living cells undergoing phagocytosis, PLD1 vesicles are recruited to nascent and internalized phagosomes, whereas PLD2 is only observed on nascent phagosomes. These results provide evidence that both PLD isoforms are required for phagosome formation, but only PLD1 seems to be implicated in later stages of phagocytosis occurring after phagosomal internalization.
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Affiliation(s)
- Matthias Corrotte
- Département Neurotransmission et Sécrétion Neuroendocrine, UMR 7168/LC2, CNRS/Université Louis Pasteur, Strasbourg, France
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Meyer MZ, Déliot N, Chasserot-Golaz S, Premont RT, Bader MF, Vitale N. Regulation of neuroendocrine exocytosis by the ARF6 GTPase-activating protein GIT1. J Biol Chem 2006; 281:7919-26. [PMID: 16439353 DOI: 10.1074/jbc.m600081200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neuroendocrine cells release hormones and neuropeptides by exocytosis, a highly regulated process in which secretory granules fuse with the plasma membrane to release their contents in response to a calcium trigger. Using chromaffin and PC12 cells, we have recently described that the granule-associated GTPase ARF6 plays a crucial role in exocytosis by activating phospholipase D1 at the plasma membrane and, presumably, promoting the fusion reaction between the two membrane bilayers. ARF6 is activated by the nucleotide exchange factor ARNO following docking of granules to the plasma membrane. We show here that GIT1, a GTPase-activating protein stimulating GTP hydrolysis on ARF6, is the second molecular partner that turns over the GDP/GTP cycle of ARF6 during cell stimulation. Western blot and immunofluorescence experiments indicated that GIT1 is cytosolic in resting cells but is recruited to the plasma membrane in stimulated cells, where it co-localizes with ARF6 at the granule docking sites. Over-expression of wild-type GIT1 inhibits growth hormone secretion from PC12 cells; this inhibitory effect was not observed in cells expressing a GIT1 mutant impaired in its ARF-GTPase-activating protein (GAP) activity or in cells expressing other ARF6-GAPs. Conversely reduction of GIT1 by RNA interference increased the exocytotic activity. Using a real time assay for individual chromaffin cells, we found that microinjection of GIT1 strongly reduced the number of exocytotic events. These results provide the first evidence that GIT1 plays a function in calcium-regulated exocytosis in neuroendocrine cells. We propose that GIT1 represents part of the pathway that inactivates ARF6-dependent reactions and thereby negatively regulates and/or terminates exocytotic release.
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Affiliation(s)
- Maria Zeniou Meyer
- Department of Neurotransmission and Neuroendocrine Secretion, Institut des Neurosciences Cellulaires et Intégratives UMR-7168 CNRS/Université Louis Pasteur, 5 rue Blaise Pascal, 67084 Strasbourg, France
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Waselle L, Gerona RRL, Vitale N, Martin TFJ, Bader MF, Regazzi R. Role of Phosphoinositide Signaling in the Control of Insulin Exocytosis. Mol Endocrinol 2005; 19:3097-106. [PMID: 16081518 DOI: 10.1210/me.2004-0530] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Phosphoinositides (PI) are important signaling molecules involved in the regulation of vesicular trafficking. We found that phosphatidylinositol 4-phosphate (PI4P) and phosphatidylinositol 4,5-biphosphate [PI(4,5)P(2)] increase the secretory response triggered by 10 mum Ca(2+) in streptolysin-O-permeabilized insulin-secreting INS-1E cells. In addition, nutrient-induced exocytosis was diminished in intact cells expressing constructs that sequester PI(4,5)P(2) and in cells transfected with constructs that reduce by RNA interference the level of two enzymes involved in PI(4,5)P(2) production, type III PI4-kinase beta and type I phosphatidylinositol 4-bisphosphate 5-kinase-gamma. To clarify the mechanism of action of PI, we investigated the involvement in the regulation of insulin exocytosis of three potential PI targets, phospholipase D1, the Ca(2+)-dependent activator protein for secretion 1, and Munc18-interacting protein 1. Transfection of insulin-secreting cells with plasmids that direct the synthesis of small interfering RNAs capable of reducing the endogenous levels of these proteins inhibited hormone release elicited by glucose- and cAMP-elevating agents without affecting basal release. Our data indicate that the production of PI(4,5)P(2) is necessary for proper control of beta-cell secretion and suggest that at least part of the effect of PI on insulin exocytosis could be exerted through the activation of phospholipase D1, Ca(2+)-dependent activator protein for secretion 1, and Munc18-interacting protein 1.
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Affiliation(s)
- Laurent Waselle
- Department of Cell Biology and Morphology, rue du Bugnon 9, 1005 Lausanne, Switzerland
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Vitale N, Mawet J, Camonis J, Regazzi R, Bader MF, Chasserot-Golaz S. The Small GTPase RalA controls exocytosis of large dense core secretory granules by interacting with ARF6-dependent phospholipase D1. J Biol Chem 2005; 280:29921-8. [PMID: 15980073 DOI: 10.1074/jbc.m413748200] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [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: 11/06/2022] Open
Abstract
RalA and RalB constitute a family of highly similar Ras-related GTPases widely distributed in different tissues. Recently, active forms of Ral proteins have been shown to bind to the exocyst complex, implicating them in the regulation of cellular secretion. Since RalA is present on the plasma membrane in neuroendocrine chromaffin and PC12 cells, we investigated the potential role of RalA in calcium-regulated exocytotic secretion. We show here that endogenous RalA is activated during exocytosis. Expression of the constitutively active RalA (G23V) mutant enhances secretagogue-evoked secretion from PC12 cells. Conversely, expression of the constitutively inactive GDP-bound RalA (G26A) or silencing of the RalA gene by RNA interference led to a strong impairment of the exocytotic response. RalA was found to co-localize with phospholipase D1 (PLD1) at the plasma membrane in PC12 cells. We demonstrate that cell stimulation triggers a direct interaction between RalA and ARF6-activated PLD1. Moreover, reduction of endogenous RalA expression level interfered with the activation of PLD1 observed in secretagogue-stimulated cells. Finally, using various RalA mutants selectively impaired in their ability to activate downstream effectors, we show that PLD1 activation is essential for the activation of secretion by GTP-loaded RalA. Together, these results provide evidence that RalA is a positive regulator of calcium-evoked exocytosis of large dense core secretory granules and suggest that stimulation of PLD1 and consequent changes in plasma membrane phospholipid composition is the major function RalA undertakes in calcium-regulated exocytosis.
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Affiliation(s)
- Nicolas Vitale
- Centre National de la Recherche Scientifique, Unité Propre de Recherche 2356 Neurotransmission and Sécrétion Neuroendocrine, Strasbourg France
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Chasserot-Golaz S, Vitale N, Umbrecht-Jenck E, Knight D, Gerke V, Bader MF. Annexin 2 promotes the formation of lipid microdomains required for calcium-regulated exocytosis of dense-core vesicles. Mol Biol Cell 2005; 16:1108-19. [PMID: 15635098 PMCID: PMC551477 DOI: 10.1091/mbc.e04-07-0627] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Annexin 2 is a calcium-dependent phospholipid-binding protein that has been implicated in a number of membrane-related events, including regulated exocytosis. In chromaffin cells, we previously reported that catecholamine secretion requires the translocation and formation of the annexin 2 tetramer near the exocytotic sites. Here, to obtain direct evidence for a role of annexin 2 in exocytosis, we modified its expression level in chromaffin cells by using the Semliki Forest virus expression system. Using a real-time assay for individual cells, we found that the reduction of cytosolic annexin 2, and the consequent decrease of annexin 2 tetramer at the cell periphery, strongly inhibited exocytosis, most likely at an early stage before membrane fusion. Secretion also was severely impaired in cells expressing a chimera that sequestered annexin 2 into cytosolic aggregates. Moreover, we demonstrate that secretagogue-evoked stimulation triggers the formation of lipid rafts in the plasma membrane, essential for exocytosis, and which can be attributed to the annexin 2 tetramer. We propose that annexin 2 acts as a calcium-dependent promoter of lipid microdomains required for structural and spatial organization of the exocytotic machinery.
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Affiliation(s)
- Sylvette Chasserot-Golaz
- Centre National de la Recherche Scientifique, Unité Propre de Recherche 2356, IFR 37 des Neurosciences, 67084 Strasbourg Cedex, France
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Bader MF, Doussau F, Chasserot-Golaz S, Vitale N, Gasman S. Coupling actin and membrane dynamics during calcium-regulated exocytosis: a role for Rho and ARF GTPases. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 2004; 1742:37-49. [PMID: 15590054 DOI: 10.1016/j.bbamcr.2004.09.028] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Revised: 09/22/2004] [Accepted: 09/24/2004] [Indexed: 10/26/2022]
Abstract
Release of neurotransmitters and hormones occurs by calcium-regulated exocytosis, a process that shares many similarities in neurons and neuroendocrine cells. Exocytosis is confined to specific regions in the plasma membrane, where actin remodelling, lipid modifications and protein-protein interactions take place to mediate vesicle/granule docking, priming and fusion. The spatial and temporal coordination of the various players to form a "fast and furious" machinery for secretion remain poorly understood. ARF and Rho GTPases play a central role in coupling actin dynamics to membrane trafficking events in eukaryotic cells. Here, we review the role of Rho and ARF GTPases in supplying actin and lipid structures required for synaptic vesicle and secretory granule exocytosis. Their possible functional interplay may provide the molecular cues for efficient and localized exocytotic fusion.
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Affiliation(s)
- Marie-France Bader
- CNRS UPR-2356 Neurotransmission and Sécrétion Neuroendocrine INSERM, 5 rue Blaise Pascal, 67084 Strasbourg, France.
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Ciesielski-Treska J, Grant NJ, Ulrich G, Corrotte M, Bailly Y, Haeberle AM, Chasserot-Golaz S, Bader MF. Fibrillar prion peptide (106-126) and scrapie prion protein hamper phagocytosis in microglia. Glia 2004; 46:101-15. [PMID: 15042579 DOI: 10.1002/glia.10363] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [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: 01/16/2023]
Abstract
The inflammatory response in prion diseases is dominated by microglial activation. As macrophages of the central nervous system, the phagocytic capacity of microglia is well recognized, and it is possible that microglia are involved in the removal and processing of amyloid fibrils, thus preventing their harmful effect. We have analyzed the effects of a synthetic peptide of the human prion protein, PrP(106-126), which can form fibrils, and the pathogenic form of prion protein, PrPsc, on phagocytosis in microglia isolated from neonatal rat brain cultures. To some extent, fibrillar PrP(106-126) is internalized and processed. However, both synthetic prion peptide PrP(106-126) in a fibrillar form and pathogenic prion protein PrPsc severely hamper the phagocytic activity as measured by the uptake of beads by microglia. At a concentration that does not induce microglial death, PrP(106-126) reduced the number of beads internalized and altered their cytoplasmic distribution. This effect was not due to decreased binding of beads to the cell surface, nor restricted to specific classes of receptors. Although the PrP(106-126) did not prevent F-actin and Rac1 accumulation at sites of particle engulfment, it appeared to interfere with a later step of the internalization process.
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Affiliation(s)
- Jaroslava Ciesielski-Treska
- CNRS UPR-2356 Neurotransmission et Sécrétion Neuroendocrine, IFR 37 des Neurosciences Centre de Neurochimie, Strasbourg, France.
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Gasman S, Chasserot-Golaz S, Malacombe M, Way M, Bader MF. Regulated exocytosis in neuroendocrine cells: a role for subplasmalemmal Cdc42/N-WASP-induced actin filaments. Mol Biol Cell 2003; 15:520-31. [PMID: 14617808 PMCID: PMC329227 DOI: 10.1091/mbc.e03-06-0402] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.3] [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: 11/11/2022] Open
Abstract
In neuroendocrine cells, actin reorganization is a prerequisite for regulated exocytosis. Small GTPases, Rho proteins, represent potential candidates coupling actin dynamics to membrane trafficking events. We previously reported that Cdc42 plays an active role in regulated exocytosis in chromaffin cells. The aim of the present work was to dissect the molecular effector pathway integrating Cdc42 to the actin architecture required for the secretory reaction in neuroendocrine cells. Using PC12 cells as a secretory model, we show that Cdc42 is activated at the plasma membrane during exocytosis. Expression of the constitutively active Cdc42(L61) mutant increases the secretory response, recruits neural Wiskott-Aldrich syndrome protein (N-WASP), and enhances actin polymerization in the subplasmalemmal region. Moreover, expression of N-WASP stimulates secretion by a mechanism dependent on its ability to induce actin polymerization at the cell periphery. Finally, we observed that actin-related protein-2/3 (Arp2/3) is associated with secretory granules and that it accompanies granules to the docking sites at the plasma membrane upon cell activation. Our results demonstrate for the first time that secretagogue-evoked stimulation induces the sequential ordering of Cdc42, N-WASP, and Arp2/3 at the interface between granules and the plasma membrane, thereby providing an actin structure that makes the exocytotic machinery more efficient.
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Affiliation(s)
- Stéphane Gasman
- Centre National de la Recherche Scientifique Unité Propre de Recherche 2356, Institut Fédératif de Recherche 37, 67084 Strasbourg, France.
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Abstract
Neurons and neuroendocrine cells release transmitters and hormones by exocytosis, a highly regulated process in which secretory vesicles or granules fuse with the plasma membrane to release their contents in response to a calcium trigger. Several stages have been recognized in exocytosis. After recruitment and docking at the plasma membrane, vesicles/granules enter a priming step, which is then followed by the fusion process. Cortical actin remodelling accompanies the exocytotic reaction, but the links between actin dynamics and trafficking events remain poorly understood. Here, we review the action of Rho and ADP-ribosylation factor (ARF) GTPases within the exocytotic pathway in adrenal chromaffin cells. Rho proteins are well known for their pivotal role in regulating the actin cytoskeleton. ARFs were originally identified as regulators of vesicle transport within cells. The possible interplay between these two families of GTPases and their downstream effectors provides novel insights into the mechanisms that govern exocytosis.
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Affiliation(s)
- Stéphane Gasman
- CNRS UPR-2356 Neurotransmission et Sécrétion Neuroendocrine, Centre de Neurochimie, 5 rue Blaise Pascal, 67084 Strasbourg, France
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Du G, Altshuller YM, Vitale N, Huang P, Chasserot-Golaz S, Morris AJ, Bader MF, Frohman MA. Regulation of phospholipase D1 subcellular cycling through coordination of multiple membrane association motifs. J Cell Biol 2003; 162:305-15. [PMID: 12876278 PMCID: PMC2172799 DOI: 10.1083/jcb.200302033] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The signaling enzyme phospholipase D1 (PLD1) facilitates membrane vesicle trafficking. Here, we explore how PLD1 subcellular localization is regulated via Phox homology (PX) and pleckstrin homology (PH) domains and a PI4,5P2-binding site critical for its activation. PLD1 localized to perinuclear endosomes and Golgi in COS-7 cells, but on cellular stimulation, translocated to the plasma membrane in an activity-facilitated manner and then returned to the endosomes. The PI4,5P2-interacting site sufficed to mediate outward translocation and association with the plasma membrane. However, in the absence of PX and PH domains, PLD1 was unable to return efficiently to the endosomes. The PX and PH domains appear to facilitate internalization at different steps. The PH domain drives PLD1 entry into lipid rafts, which we show to be a step critical for internalization. In contrast, the PX domain appears to mediate binding to PI5P, a lipid newly recognized to accumulate in endocytosing vesicles. Finally, we show that the PH domain-dependent translocation step, but not the PX domain, is required for PLD1 to function in regulated exocytosis in PC12 cells. We propose that PLD1 localization and function involves regulated and continual cycling through a succession of subcellular sites, mediated by successive combinations of membrane association interactions.
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Affiliation(s)
- Guangwei Du
- Department of Pharmacology, University Medical Center, State University of New York at Stony Brook, Stony Brook, NY 11794, USA
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Vitale N, Chasserot-Golaz S, Bailly Y, Morinaga N, Frohman MA, Bader MF. Calcium-regulated exocytosis of dense-core vesicles requires the activation of ADP-ribosylation factor (ARF)6 by ARF nucleotide binding site opener at the plasma membrane. J Cell Biol 2002; 159:79-89. [PMID: 12379803 PMCID: PMC2173505 DOI: 10.1083/jcb.200203027] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [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
The ADP ribosylation factor (ARF) GTP binding proteins are believed to mediate cytoskeletal remodeling and vesicular trafficking along the secretory pathway. Here we show that ARF6 is specifically associated with dense-core secretory granules in neuroendocrine PC12 cells. Stimulation with a secretagogue triggers the recruitment of secretory granules to the cell periphery and the concomitant activation of ARF6 by the plasma membrane-associated guanine nucleotide exchange factor, ARF nucleotide binding site opener (ARNO). Expression of the constitutively inactive ARF6(T27N) mutant inhibits secretagogue-dependent exocytosis from PC12 cells. Using a mutant of ARF6 specifically impaired for PLD1 stimulation, we find that ARF6 is functionally linked to phospholipase D (PLD)1 in the exocytotic machinery. Finally, we show that ARNO, ARF6, and PLD1 colocalize at sites of exocytosis, and we demonstrate direct interaction between ARF6 and PLD1 in stimulated cells. Together, these results provide the first direct evidence that ARF6 plays a role in calcium-regulated exocytosis in neuroendocrine cells, and suggest that ARF6-stimulated PLD1 activation at the plasma membrane and consequent changes in membrane phospholipid composition are critical for formation of the exocytotic fusion pore.
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Affiliation(s)
- Nicolas Vitale
- Unité Propre de Recherche 2356, Centre National de la Recherche Scientifique, 67084 Strasbourg Cedex, France.
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Abstract
Chromogranin (CgA), a protein upregulated in many neuropathologies, can induce an activated phenotype in microglial cells that leads to neuronal apoptosis. The death-signaling pathways mobilized in neurons involve the death receptor Fas, p38 MAP kinase, and mitochondrial cytochrome c. We propose that CgA represents a potent endogenous inflammatory factor responsible for neuronal degeneration.
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Affiliation(s)
- Gabrielle Ulrich
- CNRS UPR-2356 Neurotransmission et Secretion Neuroendocrine 5, 67084 Strasbourg Cedex, France
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Vitale N, Chasserot-Golaz S, Bader MF. Regulated secretion in chromaffin cells: an essential role for ARF6-regulated phospholipase D in the late stages of exocytosis. Ann N Y Acad Sci 2002; 971:193-200. [PMID: 12438119 DOI: 10.1111/j.1749-6632.2002.tb04463.x] [Citation(s) in RCA: 31] [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: 11/26/2022]
Abstract
ARFs constitute a family of structurally related proteins that forms a subset of the ras GTPases. In chromaffin cells, secretagogue-evoked stimulation triggers the rapid translocation of ARF6 from secretory granules to the plasma membrane and the concomitant activation of PLD in the plasma membrane. Both PLD activation and catecholamine secretion are strongly inhibited by a synthetic peptide corresponding to the N-terminal domain of ARF6. ARNO, a potential guanine nucleotide exchange factor for ARF6, is expressed and localized in the plasma membrane of chromaffin cells. Using permeabilized cells, we found that the introduction of anti-ARNO antibodies into the cytosol inhibits both PLD activation and catecholamine secretion. Chromaffin cells express PLD1 at the plasma membrane. We found that microinjection of the catalytically inactive PLD1(K898R) dramatically reduces catecholamine secretion monitored by amperometry, most likely by interfering with a late postdocking step of calcium-regulated exocytosis. We propose that ARNO-ARF6 participate in the exocytotic reaction by controlling the plasma membrane-bound PLD1. By generating fusogenic lipids at the exocytotic sites, PLD1 may represent an essential component of the fusion machinery in neuroendocrine cells.
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Affiliation(s)
- Nicolas Vitale
- CNRS UPR-2356 Neurotransmission et Sécrétion Neuroendocrine, 67084 Strasbourg cedex, France.
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Abstract
Neurons and neuroendocrine cells release transmitters and hormones by exocytosis of secrctory vesicles or granules. Among the cell models that have provided insight into the molecular machinery underlying the successive steps of exocytosis, adrenal chromaffin cells have taken a prominent place. Thus, most of the molecular players that orchestrate the formation, targeting, docking, and fusion of secrctory granules have been identified in chromaffin cells. By offering the opportunity to combine the use of recent biophysical techniques allowing single-vesicle resolution and specific biochemical modifications in the protein machinery involved in exocytosis, chromaffn cells remain a powerful model to address new and still open questions in the field of secretion.
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Affiliation(s)
- Marie-France Bader
- CNRS UPR-2356 Neurotransmission et Sécrétion Neuroendocrine, 67084 Strasbourg cedex, France.
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Mukherjee S, Gurevich VV, Preninger A, Hamm HE, Bader MF, Fazleabas AT, Birnbaumer L, Hunzicker-Dunn M. Aspartic acid 564 in the third cytoplasmic loop of the luteinizing hormone/choriogonadotropin receptor is crucial for phosphorylation-independent interaction with arrestin2. J Biol Chem 2002; 277:17916-27. [PMID: 11867621 DOI: 10.1074/jbc.m110479200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Arrestin2 binding to the active but unphosphorylated luteinizing hormone/choriogonadotropin receptor (LH/CG R) in ovarian follicles is triggered by activation of ADP-ribosylation factor 6 (ARF6) and leads to uncoupling of this receptor from cAMP signaling. We sought to determine how arrestin2 binds to LH/CG R, if binding is of high affinity, and if the receptor also binds arrestin3. Desensitization of intact LH/CG R was equally sensitive to ectopic constructs of arrestin2 that bind other G protein-coupled receptors (GPCRs) either in a phosphorylation-independent or -dependent manner. Intact LH/CG R was not desensitized by ectopic arrestin3 constructs. Surface plasmon resonance studies showed that arrestin2 bound a synthetic third intracellular (3i) LH/CG R loop peptide with picomolar affinity; arrestin3 bound with millimolar affinity. To determine whether Asp-564 in the 3i loop mimicked the phosphorylated residue of other GPCRs, human embryonic kidney (HEK) cells were transfected with wild-type (WT) and D564G LH/CG R. An agonist-stimulated ARF6-dependent arrestin2 undocking pathway to drive desensitization of WT receptor was recapitulated in HEK cell membranes, and ectopic arrestin2 promoted desensitization of WT LH/CG R. However, D564G LH/CG R in HEK cells was not desensitized, and synthetic 3i D564G peptide did not bind arrestin2. Synthetic 3i loop peptides containing D564E, D564V, or D564N also did not bind arrestin2. We conclude that the ARF6-mediated mechanism to release a pool of membrane-delimited arrestin to bind GPCRs may be a widespread mechanism to deliver arrestin to GPCRs for receptor desensitization. Unlike other GPCRs that additionally require receptor phosphorylation, LH/CG R activation is sufficient to expose a conformation in which Asp-564 in the 3i loop confers high affinity binding selectively to arrestin2.
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Affiliation(s)
- Sutapa Mukherjee
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
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Humeau Y, Vitale N, Chasserot-Golaz S, Dupont JL, Du G, Frohman MA, Bader MF, Poulain B. A role for phospholipase D1 in neurotransmitter release. Proc Natl Acad Sci U S A 2001; 98:15300-5. [PMID: 11752468 PMCID: PMC65024 DOI: 10.1073/pnas.261358698] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Phosphatidic acid produced by phospholipase D (PLD) as a result of signaling activity is thought to play a role in membrane vesicle trafficking, either as an intracellular messenger or as a cone-shaped lipid that promotes membrane fusion. We recently described that, in neuroendocrine cells, plasma membrane-associated PLD1 operates at a stage of Ca(2+)-dependent exocytosis subsequent to cytoskeletal-mediated recruitment of secretory granules to exocytotic sites. We show here that PLD1 also plays a crucial role in neurotransmitter release. Using purified rat brain synaptosomes subjected to hypotonic lysis and centrifugation, we found that PLD1 is associated with the particulate fraction containing the plasma membrane. Immunostaining of rat cerebellar granule cells confirmed localization of PLD1 at the neuronal plasma membrane in zones specialized for neurotransmitter release (axonal neurites, varicosities, and growth cone-like structures). To determine the potential involvement of PLD1 in neurotransmitter release, we microinjected catalytically inactive PLD1(K898R) into Aplysia neurons and analyzed its effects on evoked acetylcholine (ACh) release. PLD1(K898R) produced a fast and potent dose-dependent inhibition of ACh release. By analyzing paired-pulse facilitation and postsynaptic responses evoked by high-frequency stimulations, we found that the exocytotic inhibition caused by PLD1(K898R) was not the result of an alteration in stimulus-secretion coupling or in vesicular trafficking. Analysis of the fluctuations in amplitude of the postsynaptic responses revealed that the PLD1(K898R) blocked ACh release by reducing the number of active presynaptic-releasing sites. Our results provide evidence that PLD1 plays a major role in neurotransmission, most likely by controlling the fusogenic status of presynaptic release sites.
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Affiliation(s)
- Y Humeau
- Centre National de la Recherche Scientifique, Unité Propre de Recherche 2356, Neurotransmission et Sécrétion Neuroendocrine, 5 Rue Blaise Pascal, IFR37, 67084 Strasbourg, France
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Salvador LM, Mukherjee S, Kahn RA, Lamm ML, Fazleabas AT, Maizels ET, Bader MF, Hamm H, Rasenick MM, Casanova JE, Hunzicker-Dunn M. Activation of the luteinizing hormone/choriogonadotropin hormone receptor promotes ADP ribosylation factor 6 activation in porcine ovarian follicular membranes. J Biol Chem 2001; 276:33773-81. [PMID: 11448949 DOI: 10.1074/jbc.m101498200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previously we demonstrated in a cell-free ovarian follicular plasma membrane model that agonist-dependent desensitization of the luteinizing hormone/choriogonadotropin receptor (LH/CG R) is GTP-dependent, mimicked by the addition of ADP-ribosylation factor (ARF) nucleotide binding site opener, which acts as a guanine nucleotide exchange factor for ARFs 1 and 6, and selectively inhibited by synthetic N-terminal ARF6 peptides. We therefore sought direct evidence that activation of the LH/CG R promotes activation of ARF1 and/or ARF6. Using a classic ARF activation assay, the cholera toxin-catalyzed ADP-ribosylation of G alpha(s), results show that LH/CG R activation stimulates an ARF protein by a brefeldin A-independent mechanism. Synthetic N-terminal inhibitory ARF6 but not ARF1 peptide blocks LH/CG R-stimulated ARF activity. LH/CG R activation also promotes the binding of a photoaffinity GTP analog to a protein that migrates on one- and two-dimensional polyacrylamide gel electrophoresis with ARF6. These results suggest that ARF6 is the predominant ARF activated by the LH/CG R. To activate ARF6, the LH/CG R does not appear to signal through the C-terminal regions of G alpha(i) or G alpha(q) or through the second or third intracellular loops or the N terminus of the cytoplasmic tail of the LH/CG R. Although exogenous recombinant ARNO promotes only a small increase in ARF6 activation in the presence of activated LH/CG R, hCG-stimulated ARF6 activation is reduced to basal levels by catalytically inactive ARF nucleotide binding-site opener. These results provide direct evidence that LH/CG R activation leads to the activation of membrane-delimited ARF6.
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Affiliation(s)
- L M Salvador
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
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Vitale N, Caumont AS, Chasserot-Golaz S, Du G, Wu S, Sciorra VA, Morris AJ, Frohman MA, Bader MF. Phospholipase D1: a key factor for the exocytotic machinery in neuroendocrine cells. EMBO J 2001; 20:2424-34. [PMID: 11350931 PMCID: PMC125248 DOI: 10.1093/emboj/20.10.2424] [Citation(s) in RCA: 195] [Impact Index Per Article: 8.5] [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: 11/13/2022] Open
Abstract
Phospholipase D (PLD) has been proposed to mediate cytoskeletal remodeling and vesicular trafficking along the secretory pathway. We recently described the activation of an ADP ribosylation factor-regulated PLD at the plasma membrane of chromaffin cells undergoing secretagogue-stimulated exocytosis. We show here that the isoform involved is PLD1b, and, using a real-time assay for individual cells, that PLD activation and exocytosis are closely correlated. Moreover, overexpressed PLD1, but not PLD2, increases stimulated exocytosis in a phosphatidylinositol 4,5-bisphosphate-dependent manner, whereas catalytically inactive PLD1 inhibits it. These results provide the first direct evidence that PLD1 is an important component of the exocytotic machinery in neuroendocrine cells.
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Affiliation(s)
| | | | | | - Guangwei Du
- CNRS-UPR 2356 Neurotransmission et Sécrétion Neuroendocrine, 5 rue Blaise Pascal, 67084 Strasbourg, France and
Department of Pharmacology and Center for Developmental Genetics, University Medical Center at Stony Brook, Stony Brook, NY 11794-5140, USA Corresponding author e-mail: N.Vitale and A.-S.Caumont contributed equally to this work
| | - Si Wu
- CNRS-UPR 2356 Neurotransmission et Sécrétion Neuroendocrine, 5 rue Blaise Pascal, 67084 Strasbourg, France and
Department of Pharmacology and Center for Developmental Genetics, University Medical Center at Stony Brook, Stony Brook, NY 11794-5140, USA Corresponding author e-mail: N.Vitale and A.-S.Caumont contributed equally to this work
| | - Vicki A. Sciorra
- CNRS-UPR 2356 Neurotransmission et Sécrétion Neuroendocrine, 5 rue Blaise Pascal, 67084 Strasbourg, France and
Department of Pharmacology and Center for Developmental Genetics, University Medical Center at Stony Brook, Stony Brook, NY 11794-5140, USA Corresponding author e-mail: N.Vitale and A.-S.Caumont contributed equally to this work
| | - Andrew J. Morris
- CNRS-UPR 2356 Neurotransmission et Sécrétion Neuroendocrine, 5 rue Blaise Pascal, 67084 Strasbourg, France and
Department of Pharmacology and Center for Developmental Genetics, University Medical Center at Stony Brook, Stony Brook, NY 11794-5140, USA Corresponding author e-mail: N.Vitale and A.-S.Caumont contributed equally to this work
| | - Michael A. Frohman
- CNRS-UPR 2356 Neurotransmission et Sécrétion Neuroendocrine, 5 rue Blaise Pascal, 67084 Strasbourg, France and
Department of Pharmacology and Center for Developmental Genetics, University Medical Center at Stony Brook, Stony Brook, NY 11794-5140, USA Corresponding author e-mail: N.Vitale and A.-S.Caumont contributed equally to this work
| | - Marie-France Bader
- CNRS-UPR 2356 Neurotransmission et Sécrétion Neuroendocrine, 5 rue Blaise Pascal, 67084 Strasbourg, France and
Department of Pharmacology and Center for Developmental Genetics, University Medical Center at Stony Brook, Stony Brook, NY 11794-5140, USA Corresponding author e-mail: N.Vitale and A.-S.Caumont contributed equally to this work
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Ciesielski-Treska J, Ulrich G, Chasserot-Golaz S, Zwiller J, Revel MO, Aunis D, Bader MF. Mechanisms underlying neuronal death induced by chromogranin A-activated microglia. J Biol Chem 2001; 276:13113-20. [PMID: 11124958 DOI: 10.1074/jbc.m009711200] [Citation(s) in RCA: 58] [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: 12/22/2022] Open
Abstract
The neurotoxic effects of activated microglia in neurodegenerative diseases are well established. We recently provided evidence that chromogranin A (CGA), a multifunctional protein localized in dystrophic neurites and in senile plaques, induces an activated phenotype and secretion of neurotoxins by rat microglia in culture. In the present study, we focused on the mechanisms underlying neuronal degeneration triggered by CGA-activated microglia. We found that neuronal death exhibits apoptotic features, characterized by the externalization of phosphatidylserine and the fragmentation of DNA. Microglial neurotoxins markedly stimulate the phosphorylation and activity of neuronal p38 mitogen-activated protein kinase and provoke the release of mitochondrial cytochrome c, which precedes apoptosis. Inhibition of p38 kinase with SB 203580 partially protects neurons from death induced by CGA-activated microglia. Furthermore, neurons are also protected by Fas-Fc, which antagonizes the interactions between the death receptor Fas and its ligand FasL and by cell-permeable peptides that inhibit caspases 8 and 3. Thus, CGA triggers the release of microglial neurotoxins that mobilize several death-signaling pathways in neurons. Our results further support the idea that CGA, which is up-regulated in many neuropathologies, represents a potent endogeneous inflammatory factor possibly responsible for neuronal degeneration.
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Affiliation(s)
- J Ciesielski-Treska
- Unité INSERM U-338 de Biologie de la Communication Cellulaire, Centre de Neurochimie, 5 rue Blaise Pascal, 67084 Strasbourg Cedex, France.
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Le Stunff H, Dokhac L, Bourgoin S, Bader MF, Harbon S. Phospholipase D in rat myometrium: occurrence of a membrane-bound ARF6 (ADP-ribosylation factor 6)-regulated activity controlled by betagamma subunits of heterotrimeric G-proteins. Biochem J 2000; 352 Pt 2:491-9. [PMID: 11085943 PMCID: PMC1221481 DOI: 10.1042/0264-6021:3520491] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Both protein kinase C and protein tyrosine kinases have been shown to be involved in phospholipase D (PLD) activation in intact rat myometrium [Le Stunff, Dokhac and Harbon (2000) J. Pharmacol. Exp. Ther. 292, 629-637]. In this study we assessed the involvement of monomeric G-proteins in PLD activation in a cell-free system derived from myometrial tissue. Both the PLD1 and PLD2 isoforms were detected. Two forms of PLD activity, essentially membrane-bound, were found in myometrial preparations. One form was stimulated by oleate and insensitive to guanosine 5'-[gamma-thio] triphosphate (GTP[S]). The second required ammonium sulphate to be detected and was stimulated by GTP[S]. ADP-ribosylation factors (ARF1 and ARF6) and RhoA were immunodetected in myometrial preparations. ARF1 and RhoA were present in the membrane and cytosolic fractions whereas ARF6 was detected exclusively in the membrane fraction. A synthetic myristoylated peptide corresponding to the N-terminal domain of ARF6 [myrARF6((2-13))] totally abolished PLD activation in the presence of ammonium sulphate and GTP[S], whereas myrARF1((2-17)) and the inhibitory GDP/GTP-exchange factor, Rho GDI, did not. These data are consistent with a membrane-bound ARF6-regulated PLD activity. Finally, the stimulation of PLD by ARF6 was inhibited by AlF(-)(4) and this inhibition was counteracted by the fusion protein glutathione S-transferase-beta-adrenergic receptor kinase 1 (495-689) and by the QEHA peptide (from adenylate cyclase ACII), which act as G-protein betagamma-subunit scavengers. It is concluded that G-protein subunits betagamma are involved in a pathway modulating PLD activation by ARF6, illustrating cross-talk between heterotrimeric and monomeric G-proteins.
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Affiliation(s)
- H Le Stunff
- Signalisation et Régulations Cellulaires, CNRS UMR 8619, Bâtiment 432, Université Paris-Sud, 91405 Orsay Cedex, France
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