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Okafor M, Champomier O, Raibaut L, Ozkan S, El Kholti N, Ory S, Chasserot-Golaz S, Gasman S, Hureau C, Faller P, Vitale N. Restoring cellular copper homeostasis in Alzheimer disease: a novel peptide shuttle is internalized by an ATP-dependent endocytosis pathway involving Rab5- and Rab14-endosomes. Front Mol Biosci 2024; 11:1355963. [PMID: 38645276 PMCID: PMC11026709 DOI: 10.3389/fmolb.2024.1355963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/11/2024] [Indexed: 04/23/2024] Open
Abstract
CPPs, or Cell-Penetrating Peptides, offer invaluable utility in disease treatment due to their ability to transport various therapeutic molecules across cellular membranes. Their unique characteristics, such as biocompatibility and low immunogenicity, make them ideal candidates for delivering drugs, genes, or imaging agents directly into cells. This targeted delivery enhances treatment efficacy while minimizing systemic side effects. CPPs exhibit versatility, crossing biological barriers and reaching intracellular targets that conventional drugs struggle to access. This capability holds promise in treating a wide array of diseases, including cancer, neurodegenerative disorders, and infectious diseases, offering a potent avenue for innovative and targeted therapies, yet their precise mechanism of cell entry is far from being fully understood. In order to correct Cu dysregulation found in various pathologies such as Alzheimer disease, we have recently conceived a peptide Cu(II) shuttle, based on the αR5W4 CPP, which, when bound to Cu(II), is able to readily enter a neurosecretory cell model, and release bioavailable Cu in cells. Furthermore, this shuttle has the capacity to protect cells in culture against oxidative stress-induced damage which occurs when Cu binds to the Aβ peptide. The aim of this study was therefore to characterize the cell entry route used by this shuttle and determine in which compartment Cu is released. Pharmacological treatments, siRNA silencing and colocalization experiments with GFP-Rab fusion proteins, indicate that the shuttle is internalized by an ATP-dependent endocytosis pathway involving both Rab5 and Rab14 endosomes route and suggest an early release of Cu from the shuttle.
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Affiliation(s)
- Michael Okafor
- Institut des Neurosciences Cellulaires et Intégratives—Centre National de la Recherche Scientifique UPR3212, Université de Strasbourg, Strasbourg, France
- Institut de Chimie—UMR7177, Université de Strasbourg, Centre National de la Recherche Scientifique, Strasbourg, France
| | - Olivia Champomier
- Institut des Neurosciences Cellulaires et Intégratives—Centre National de la Recherche Scientifique UPR3212, Université de Strasbourg, Strasbourg, France
- Institut de Chimie—UMR7177, Université de Strasbourg, Centre National de la Recherche Scientifique, Strasbourg, France
| | - Laurent Raibaut
- Institut de Chimie—UMR7177, Université de Strasbourg, Centre National de la Recherche Scientifique, Strasbourg, France
| | - Sebahat Ozkan
- Institut des Neurosciences Cellulaires et Intégratives—Centre National de la Recherche Scientifique UPR3212, Université de Strasbourg, Strasbourg, France
| | - Naima El Kholti
- Institut des Neurosciences Cellulaires et Intégratives—Centre National de la Recherche Scientifique UPR3212, Université de Strasbourg, Strasbourg, France
| | - Stéphane Ory
- Institut des Neurosciences Cellulaires et Intégratives—Centre National de la Recherche Scientifique UPR3212, Université de Strasbourg, Strasbourg, France
| | - Sylvette Chasserot-Golaz
- Institut des Neurosciences Cellulaires et Intégratives—Centre National de la Recherche Scientifique UPR3212, Université de Strasbourg, Strasbourg, France
| | - Stéphane Gasman
- Institut des Neurosciences Cellulaires et Intégratives—Centre National de la Recherche Scientifique UPR3212, Université de Strasbourg, Strasbourg, France
| | - Christelle Hureau
- Laboratoire de Chimie de Coordination, Centre National de la Recherche Scientifique UPR8241, Université de Toulouse, Toulouse, France
| | - Peter Faller
- Institut de Chimie—UMR7177, Université de Strasbourg, Centre National de la Recherche Scientifique, Strasbourg, France
- Institut Universitaire de France (IUF), Paris, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives—Centre National de la Recherche Scientifique UPR3212, Université de Strasbourg, Strasbourg, France
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Cafaro A, Schietroma I, Sernicola L, Belli R, Campagna M, Mancini F, Farcomeni S, Pavone-Cossut MR, Borsetti A, Monini P, Ensoli B. Role of HIV-1 Tat Protein Interactions with Host Receptors in HIV Infection and Pathogenesis. Int J Mol Sci 2024; 25:1704. [PMID: 38338977 PMCID: PMC10855115 DOI: 10.3390/ijms25031704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 01/19/2024] [Accepted: 01/23/2024] [Indexed: 02/12/2024] Open
Abstract
Each time the virus starts a new round of expression/replication, even under effective antiretroviral therapy (ART), the transactivator of viral transcription Tat is one of the first HIV-1 protein to be produced, as it is strictly required for HIV replication and spreading. At this stage, most of the Tat protein exits infected cells, accumulates in the extracellular matrix and exerts profound effects on both the virus and neighbor cells, mostly of the innate and adaptive immune systems. Through these effects, extracellular Tat contributes to the acquisition of infection, spreading and progression to AIDS in untreated patients, or to non-AIDS co-morbidities in ART-treated individuals, who experience inflammation and immune activation despite virus suppression. Here, we review the role of extracellular Tat in both the virus life cycle and on cells of the innate and adaptive immune system, and we provide epidemiological and experimental evidence of the importance of targeting Tat to block residual HIV expression and replication. Finally, we briefly review vaccine studies showing that a therapeutic Tat vaccine intensifies ART, while its inclusion in a preventative vaccine may blunt escape from neutralizing antibodies and block early events in HIV acquisition.
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Affiliation(s)
- Aurelio Cafaro
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, 00161 Rome, Italy; (I.S.); (L.S.); (R.B.); (M.C.); (F.M.); (S.F.); (M.R.P.-C.); (A.B.); (P.M.)
| | | | | | | | | | | | | | | | | | | | - Barbara Ensoli
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, 00161 Rome, Italy; (I.S.); (L.S.); (R.B.); (M.C.); (F.M.); (S.F.); (M.R.P.-C.); (A.B.); (P.M.)
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3
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Ghanam RH, Eastep GN, Saad JS. Structural Insights into the Mechanism of HIV-1 Tat Secretion from the Plasma Membrane. J Mol Biol 2023; 435:167880. [PMID: 36370804 PMCID: PMC9822876 DOI: 10.1016/j.jmb.2022.167880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/27/2022] [Accepted: 11/04/2022] [Indexed: 11/11/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) trans-activator of transcription (Tat) is a small, intrinsically disordered basic protein that plays diverse roles in the HIV-1 replication cycle, including promotion of efficient viral RNA transcription. Tat is released by infected cells and subsequently absorbed by healthy cells, thereby contributing to HIV-1 pathogenesis including HIV-associated neurocognitive disorder. It has been shown that, in HIV-1-infected primary CD4 T-cells, Tat accumulates at the plasma membrane (PM) for secretion, a mechanism mediated by phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). However, the structural basis for Tat interaction with the PM and thereby secretion is lacking. Herein, we employed NMR and biophysical methods to characterize Tat86 (86 amino acids) interactions with PI(4,5)P2 and lipid nanodiscs (NDs). Our data revealed that Arg49, Lys50 and Lys51 (RKK motif) constitute the PI(4,5)P2 binding site, that Tat86 interaction with lipid NDs is dependent on PI(4,5)P2 and phosphatidylserine (PS), and that the arginine-rich motif (RRQRRR) preferentially interacts with PS. Furthermore, we show that Trp11, previously implicated in Tat secretion, penetrates deeply in the membrane; substitution of Trp11 severely reduced Tat86 interaction with membranes. Deletion of the entire highly basic region and Trp11 completely abolished Tat86 binding to lipid NDs. Our data support a mechanism by which HIV-1 Tat secretion from the PM is mediated by a tripartite signal consisting of binding of the RKK motif to PI(4,5)P2, arginine-rich motif to PS, and penetration of Trp11 in the membrane. Altogether, these findings provide new insights into the molecular requirements for Tat binding to membranes during secretion.
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Affiliation(s)
- Ruba H Ghanam
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Gunnar N Eastep
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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Joliot A. Role of PI(4,5)P2 and Cholesterol in Unconventional Protein Secretion. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:381-392. [PMID: 36988889 DOI: 10.1007/978-3-031-21547-6_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Besides its protective role in the maintenance of cell homeostasis, the plasma membrane is the site of exchanges between the cell interior and the extracellular medium. To circumvent the hydrophobic barrier formed by the acyl chains of the lipid bilayer, protein channels and transporters are key players in the exchange of small hydrophilic compounds such as ions or nutrients, but they hardly account for the transport of larger biological molecules. Exchange of proteins usually relies on membrane-fusion events between vesicles and the plasma membrane. In recent years, several alternative unconventional protein secretion (UPS) pathways across the plasma membrane have been characterised for a specific set of secreted substrates, some of them excluding any membrane-fusion events (Dimou and Nickel, Curr Biol 28:R406-R410, 2018). One of thesbe pathways, referred as type I UPS, relies on the direct translocation of the protein across the plasma membrane and not surprisingly, lipids are essential players in this process. In this chapter, we discuss the roles of phosphatidylinositol(4,5)bisphosphate (PI(4,5)P2) and cholesterol in unconventional pathways involving Engrailed-2 homeoprotein and fibroblast growth factor 2.
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Affiliation(s)
- Alain Joliot
- INSERM U932, Institut Curie Centre de Recherche, PSL Research University, Paris, France.
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Wang Q, Wolf A, Ozkan S, Richert L, Mely Y, Chasserot-Golaz S, Ory S, Gasman S, Vitale N. V-ATPase modulates exocytosis in neuroendocrine cells through the activation of the ARNO-Arf6-PLD pathway and the synthesis of phosphatidic acid. Front Mol Biosci 2023; 10:1163545. [PMID: 37091866 PMCID: PMC10119424 DOI: 10.3389/fmolb.2023.1163545] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 03/23/2023] [Indexed: 04/25/2023] Open
Abstract
Although there is mounting evidence indicating that lipids serve crucial functions in cells and are implicated in a growing number of human diseases, their precise roles remain largely unknown. This is particularly true in the case of neurosecretion, where fusion with the plasma membrane of specific membrane organelles is essential. Yet, little attention has been given to the role of lipids. Recent groundbreaking research has emphasized the critical role of lipid localization at exocytotic sites and validated the essentiality of fusogenic lipids, such as phospholipase D (PLD)-generated phosphatidic acid (PA), during membrane fusion. Nevertheless, the regulatory mechanisms synchronizing the synthesis of these key lipids and neurosecretion remain poorly understood. The vacuolar ATPase (V-ATPase) has been involved both in vesicle neurotransmitter loading and in vesicle fusion. Thus, it represents an ideal candidate to regulate the fusogenic status of secretory vesicles according to their replenishment state. Indeed, the cytosolic V1 and vesicular membrane-associated V0 subdomains of V-ATPase were shown to dissociate during the stimulation of neurosecretory cells. This allows the subunits of the vesicular V0 to interact with different proteins of the secretory machinery. Here, we show that V0a1 interacts with the Arf nucleotide-binding site opener (ARNO) and promotes the activation of the Arf6 GTPase during the exocytosis in neuroendocrine cells. When the interaction between V0a1 and ARNO was disrupted, it resulted in the inhibition of PLD activation, synthesis of phosphatidic acid during exocytosis, and changes in the timing of fusion events. These findings indicate that the separation of V1 from V0 could function as a signal to initiate the ARNO-Arf6-PLD1 pathway and facilitate the production of phosphatidic acid, which is essential for effective exocytosis in neuroendocrine cells.
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Affiliation(s)
- Qili Wang
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Alexander Wolf
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Sebahat Ozkan
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Ludovic Richert
- Laboratoire de Bioimagerie et Pathologies, Faculté de Pharmacie, CNRS UMR and Université de Strasbourg, Strasbourg, France
| | - Yves Mely
- Laboratoire de Bioimagerie et Pathologies, Faculté de Pharmacie, CNRS UMR and Université de Strasbourg, Strasbourg, France
| | - Sylvette Chasserot-Golaz
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Stéphane Ory
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Stéphane Gasman
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
- *Correspondence: Nicolas Vitale,
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Abstract
Over the last four decades, chromaffin cells originating from the adrenal medulla have been probably one of the most popular cell models to study neurosecretion at the molecular level. Accordingly, numerous seminal discoveries in the field, including the characterization of role of the cytoskeleton, fusogenic lipids, and soluble N-ethylmaleimide-sensitivefactor attachment protein receptor (SNARE) proteins, have been made using this model. In this chapter, we describe a standard method currently used to isolate and culture bovine chromaffin cells, and we illustrate a catecholamine secretion assay based on the successive transformation of adrenaline into adrenochrome and adrenolutine for fluorescence measurements. We also provide some guidelines for efficient cell recovery and for the use of this assay in the laboratory.
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Priyanka, Wadhwa R, Chaudhuri R, Nag TC, Seth P. Novel role of mortalin in attenuating HIV-1 Tat-mediated astrogliosis. J Neuroinflammation 2020; 17:276. [PMID: 32951595 PMCID: PMC7504834 DOI: 10.1186/s12974-020-01912-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 07/29/2020] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND In human immunodeficiency virus-1 (HIV-1) infection, activation of astrocytes induces imbalance in physiological functions due to perturbed astrocytic functions that unleashes toxicity on neurons. This leads to inflammatory response finally culminating into neurocognitive dysfunction. In neuroAIDS, HIV-1 protein, transactivator of transcription (Tat) is detected in the cerebrospinal fluid of infected patients. Mortalin, a multifunctional protein, has anti-inflammatory role following its activation in various stress conditions. Recent studies demonstrate downregulation of mortalin in neurodegenerative diseases. Here, we explored the mechanisms of mortalin in modulating HIV-1 Tat-mediated neuroinflammation. METHODS Expression of mortalin in autopsy section in normal and diseased individuals were examined using immunohistochemistry. To decipher the role of mortalin in HIV-1 Tat-induced activation, human fetal brain-derived astrocytes were transiently transfected with Tat and mortalin using expression vectors. HIV-1 Tat-mediated damage was analyzed using RT-PCR and western blotting. Modulatory role of mortalin was examined by coexpressing it with Tat, followed by examination of mitochondrial morphodynamics using biochemical assay and confocal and electron microscopy. Extracellular ATP release was monitored using luciferase assay. Neuroinflammation in astrocytes was examined using flow cytometry, dye based study, immunocytochemistry, immunoprecipitation, and western blotting. Indirect neuronal damage was also analyzed. RESULTS HIV-1 Tat downregulates the expression of mortalin in astrocytes, and this is corroborated with autopsy sections of HIV-1 patients. We found that overexpression of mortalin with Tat reduced inflammation and also rescued astrocytic-mediated neuronal death. Using bioinformatics, we discovered that binding of mortalin with Tat leads to Tat degradation and rescues the cell from neuroinflammation. Blocking of proteosomal pathway rescued the Tat degradation and revealed the ubiquitination of Tat. CONCLUSION Overall, our data demonstrated the protective role of mortalin in combating HIV-1 Tat-mediated damage. We also showed that mortalin could degrade Tat through direct binding with HIV-1 Tat. Overexpression of mortalin in the presence of Tat could significantly reduce cytotoxic effects of Tat in astrocytes. Indirect neuronal death was also found to be rescued. Our in vitro findings were validated as we found attenuated expression of mortalin in the autopsy sections of HIV-1 patients.
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Affiliation(s)
- Priyanka
- Department of Cellular and Molecular Neuroscience, National Brain Research Centre, NH-8, Nainwal Road, Manesar, Gurgaon, Haryana, 122052, India
| | - Renu Wadhwa
- AIST-INDIA DAILAB, DBT-AIST International Center for Translational and Environmental (DAICENTER), National Institute of Advanced Industrial Science & Technology (AIST), Tsukuba, 305-8565, Japan
| | - Rituparna Chaudhuri
- Department of Cellular and Molecular Neuroscience, National Brain Research Centre, NH-8, Nainwal Road, Manesar, Gurgaon, Haryana, 122052, India
| | | | - Pankaj Seth
- Department of Cellular and Molecular Neuroscience, National Brain Research Centre, NH-8, Nainwal Road, Manesar, Gurgaon, Haryana, 122052, India.
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Mono- and Poly-unsaturated Phosphatidic Acid Regulate Distinct Steps of Regulated Exocytosis in Neuroendocrine Cells. Cell Rep 2020; 32:108026. [DOI: 10.1016/j.celrep.2020.108026] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 06/16/2020] [Accepted: 07/21/2020] [Indexed: 12/21/2022] Open
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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] [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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Cafaro A, Tripiciano A, Picconi O, Sgadari C, Moretti S, Buttò S, Monini P, Ensoli B. Anti-Tat Immunity in HIV-1 Infection: Effects of Naturally Occurring and Vaccine-Induced Antibodies Against Tat on the Course of the Disease. Vaccines (Basel) 2019; 7:vaccines7030099. [PMID: 31454973 PMCID: PMC6789840 DOI: 10.3390/vaccines7030099] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/08/2019] [Accepted: 08/15/2019] [Indexed: 02/07/2023] Open
Abstract
HIV-1 Tat is an essential protein in the virus life cycle, which is required for virus gene expression and replication. Most Tat that is produced during infection is released extracellularly and it plays a key role in HIV pathogenesis, including residual disease upon combination antiretroviral therapy (cART). Here, we review epidemiological and experimental evidence showing that antibodies against HIV-1 Tat, infrequently occurring in natural infection, play a protective role against disease progression, and that vaccine targeting Tat can intensify cART. In fact, Tat vaccination of subjects on suppressive cART in Italy and South Africa promoted immune restoration, including CD4+ T-cell increase in low immunological responders, and a reduction of proviral DNA even after six years of cART, when both CD4+ T-cell gain and DNA decay have reached a plateau. Of note, DNA decay was predicted by the neutralization of Tat-mediated entry of Env into dendritic cells by anti-Tat antibodies, which were cross-clade binding and neutralizing. Anti-Tat cellular immunity also contributed to the DNA decay. Based on these data, we propose the Tat therapeutic vaccine as a pathogenesis-driven intervention that effectively intensifies cART and it may lead to a functional cure, providing new perspectives and opportunities also for prevention and virus eradication strategies.
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Affiliation(s)
- Aurelio Cafaro
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Antonella Tripiciano
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Orietta Picconi
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Cecilia Sgadari
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Sonia Moretti
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Stefano Buttò
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Paolo Monini
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Barbara Ensoli
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy.
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11
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Chopard C, Tong PBV, Tóth P, Schatz M, Yezid H, Debaisieux S, Mettling C, Gross A, Pugnière M, Tu A, Strub JM, Mesnard JM, Vitale N, Beaumelle B. Cyclophilin A enables specific HIV-1 Tat palmitoylation and accumulation in uninfected cells. Nat Commun 2018; 9:2251. [PMID: 29884859 PMCID: PMC5993824 DOI: 10.1038/s41467-018-04674-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 05/15/2018] [Indexed: 12/21/2022] Open
Abstract
Most HIV-1 Tat is unconventionally secreted by infected cells following Tat interaction with phosphatidylinositol (4,5) bisphosphate (PI(4,5)P2) at the plasma membrane. Extracellular Tat is endocytosed by uninfected cells before escaping from endosomes to reach the cytosol and bind PI(4,5)P2. It is not clear whether and how incoming Tat concentrates in uninfected cells. Here we show that, in uninfected cells, the S-acyl transferase DHHC-20 together with the prolylisomerases cyclophilin A (CypA) and FKBP12 palmitoylate Tat on Cys31 thereby increasing Tat affinity for PI(4,5)P2. In infected cells, CypA is bound by HIV-1 Gag, resulting in its encapsidation and CypA depletion from cells. Because of the lack of this essential cofactor, Tat is not palmitoylated in infected cells but strongly secreted. Hence, Tat palmitoylation specifically takes place in uninfected cells. Moreover, palmitoylation is required for Tat to accumulate at the plasma membrane and affect PI(4,5)P2-dependent membrane traffic such as phagocytosis and neurosecretion. It is not clear whether and how incoming HIV-1 Tat accumulates in uninfected cells. Here, Chopard et al. show that, in uninfected cells, incoming Tat is palmitoylated on Cys31 by DHHC-20, which increases its affinity for PI(4,5)P2 and results in its accumulation at the plasma membrane.
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Affiliation(s)
- Christophe Chopard
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Phuoc Bao Viet Tong
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Petra Tóth
- INCI, UPR 3212 CNRS, 5 rue Blaise Pascal, 67084, Strasbourg, France.
| | - Malvina Schatz
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Hocine Yezid
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Solène Debaisieux
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Clément Mettling
- IGH, UPR 1142 CNRS, 141 Rue de la Cardonille, 34396, Montpellier, France
| | - Antoine Gross
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Martine Pugnière
- IRCM, INSERM U 1194, 208 Rue des Apothicaires, 34298, Montpellier, France
| | - Annie Tu
- INCI, UPR 3212 CNRS, 5 rue Blaise Pascal, 67084, Strasbourg, France
| | - Jean-Marc Strub
- CNRS, IPHC UMR 7178, Université de Strasbourg, 67000, Strasbourg, France
| | - Jean-Michel Mesnard
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Nicolas Vitale
- INCI, UPR 3212 CNRS, 5 rue Blaise Pascal, 67084, Strasbourg, France.,INSERM, 75654, Paris Cedex 13, France
| | - Bruno Beaumelle
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France.
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12
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Francesconi W, Berton F, Marcondes MCG. HIV-1 Tat alters neuronal intrinsic excitability. BMC Res Notes 2018; 11:275. [PMID: 29728138 PMCID: PMC5935945 DOI: 10.1186/s13104-018-3376-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 04/21/2018] [Indexed: 12/20/2022] Open
Abstract
Objective In HIV+ individuals, the virus enters the central nervous system and invades innate immune cells, producing important changes that result in neurological deficits. We aimed to determine whether HIV plays a direct role in neuronal excitability. Of the HIV peptides, Tat is secreted and acts in other cells. In order to examine whether the HIV Tat can modify neuronal excitability, we exposed primary murine hippocampal neurons to that peptide, and tested its effects on the intrinsic membrane properties, 4 and 24 h after exposure. Results The exposure of hippocampal pyramidal neurons to Tat for 4 h did not alter intrinsic membrane properties. However, we found a strong increase in intrinsic excitability, characterized by increase of the slope (Gain) of the input–output function, in cells treated with Tat for 24 h. Nevertheless, Tat treatment for 24 h did not alter the resting membrane potential, input resistance, rheobase and action potential threshold. Thus, neuronal adaptability to Tat exposure for 24 h is not applicable to basic neuronal properties. A restricted but significant effect on coupling the inputs to the outputs may have implications to our knowledge of Tat biophysical firing capability, and its involvement in neuronal hyperexcitability in neuroHIV.
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Affiliation(s)
- Walter Francesconi
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois Chicago, 6068 COMRB MC 512, Chicago, IL, 60612, USA. .,The Scripps Research Institute, 10550 North Torrey Pines Rd., La Jolla, CA, 92037, USA.
| | - Fulvia Berton
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois Chicago, 6068 COMRB MC 512, Chicago, IL, 60612, USA.,The Scripps Research Institute, 10550 North Torrey Pines Rd., La Jolla, CA, 92037, USA
| | - Maria Cecilia G Marcondes
- San Diego Biomedical Research Institute, 10865 Road to the Cure, San Diego, CA, 92121, USA. .,The Scripps Research Institute, 10550 North Torrey Pines Rd., La Jolla, CA, 92037, USA.
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13
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Mele AR, Marino J, Chen K, Pirrone V, Janetopoulos C, Wigdahl B, Klase Z, Nonnemacher MR. Defining the molecular mechanisms of HIV-1 Tat secretion: PtdIns(4,5)P 2 at the epicenter. Traffic 2018; 19:10.1111/tra.12578. [PMID: 29708629 PMCID: PMC6207469 DOI: 10.1111/tra.12578] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 04/26/2018] [Accepted: 04/26/2018] [Indexed: 12/18/2022]
Abstract
The human immunodeficiency virus type 1 (HIV-1) transactivator of transcription (Tat) protein functions both intracellularly and extracellularly. Intracellularly, the main function is to enhance transcription of the viral promoter. However, this process only requires a small amount of intracellular Tat. The majority of Tat is secreted through an unconventional mechanism by binding to phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2 ), a phospholipid in the inner leaflet of the plasma membrane that is required for secretion. This interaction is mediated by the basic domain of Tat (residues 48-57) and a conserved tryptophan (residue 11). After binding to PtdIns(4,5)P2 , Tat secretion diverges into multiple pathways, which we categorized as oligomerization-mediated pore formation, spontaneous translocation and incorporation into exosomes. Extracellular Tat has been shown to be neurotoxic and toxic to other cells of the central nervous system (CNS) and periphery, able to recruit immune cells to the CNS and cerebrospinal fluid, and alter the gene expression and morphology of uninfected cells. The effects of extracellular Tat have been examined in HIV-1-associated neurocognitive disorders (HAND); however, only a small number of studies have focused on the mechanisms underlying Tat secretion. In this review, the molecular mechanisms of Tat secretion will be examined in a variety of biologically relevant cell types.
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Affiliation(s)
- Anthony R Mele
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Jamie Marino
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Kenneth Chen
- Department of Biology, University of the Sciences, Philadelphia, Pennsylvania
| | - Vanessa Pirrone
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Chris Janetopoulos
- Department of Biology, University of the Sciences, Philadelphia, Pennsylvania
| | - Brian Wigdahl
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Zachary Klase
- Department of Biology, University of the Sciences, Philadelphia, Pennsylvania
| | - Michael R Nonnemacher
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
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14
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Gasman S, Vitale N. Lipid remodelling in neuroendocrine secretion. Biol Cell 2017; 109:381-390. [DOI: 10.1111/boc.201700030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 09/18/2017] [Accepted: 09/18/2017] [Indexed: 12/13/2022]
Affiliation(s)
- Stéphane Gasman
- Institut des Neurosciences Cellulaires et Intégratives; CNRS UPR3212; Université de Strasbourg; Strasbourg France
- INSERM; Paris Cedex 75654 France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives; CNRS UPR3212; Université de Strasbourg; Strasbourg France
- INSERM; Paris Cedex 75654 France
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15
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Phosphatidylinositol (4,5)-bisphosphate-mediated pathophysiological effect of HIV-1 Tat protein. Biochimie 2017; 141:80-85. [DOI: 10.1016/j.biochi.2017.05.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 05/21/2017] [Indexed: 11/23/2022]
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16
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How does the stimulus define exocytosis in adrenal chromaffin cells? Pflugers Arch 2017; 470:155-167. [DOI: 10.1007/s00424-017-2052-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 07/28/2017] [Accepted: 08/01/2017] [Indexed: 12/28/2022]
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17
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Niedergang F, Gasman S, Vitale N, Desnos C, Lamaze C. Meeting after meeting: 20 years of discoveries by the members of the Exocytosis-Endocytosis Club. Biol Cell 2017; 109:339-353. [DOI: 10.1111/boc.201700026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/24/2017] [Accepted: 07/24/2017] [Indexed: 11/29/2022]
Affiliation(s)
- Florence Niedergang
- Institut National de la Santé et de la Recherche Médicale (INSERM); U1016 Institut Cochin Paris France
- Centre National de la Recherche Scientifique (CNRS); UMR 8104 Paris France
- Université Paris Descartes, Sorbonne Paris Cité; Paris France
| | - Stéphane Gasman
- Institut des Neurosciences Cellulaires et Intégratives; CNRS UPR3212; Université de Strasbourg; France
- INSERM; 75654 Paris Cedex 13 France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives; CNRS UPR3212; Université de Strasbourg; France
- INSERM; 75654 Paris Cedex 13 France
| | - Claire Desnos
- Université Paris Descartes, Sorbonne Paris Cité; Paris France
- CNRS; UMR 8250 Paris France
| | - Christophe Lamaze
- Institut Curie - Centre de Recherche; PSL Research University; Membrane Dynamics and Mechanics of Intracellular Signaling Laboratory; Paris France
- CNRS; UMR 3666 Paris France
- INSERM; U1143 Paris France
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18
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Es-Salah-Lamoureux Z, Jouni M, Malak OA, Belbachir N, Al Sayed ZR, Gandon-Renard M, Lamirault G, Gauthier C, Baró I, Charpentier F, Zibara K, Lemarchand P, Beaumelle B, Gaborit N, Loussouarn G. HIV-Tat induces a decrease in I Kr and I Ks via reduction in phosphatidylinositol-(4,5)-bisphosphate availability. J Mol Cell Cardiol 2016; 99:1-13. [DOI: 10.1016/j.yjmcc.2016.08.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 08/23/2016] [Accepted: 08/29/2016] [Indexed: 02/07/2023]
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19
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Gabel M, Chasserot-Golaz S. Annexin A2, an essential partner of the exocytotic process in chromaffin cells. J Neurochem 2016; 137:890-6. [DOI: 10.1111/jnc.13628] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 03/09/2016] [Accepted: 03/30/2016] [Indexed: 12/30/2022]
Affiliation(s)
- Marion Gabel
- INCI; UPR3212 CNRS; Université de Strasbourg; Strasbourg France
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20
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Tanguy E, Carmon O, Wang Q, Jeandel L, Chasserot-Golaz S, Montero-Hadjadje M, Vitale N. Lipids implicated in the journey of a secretory granule: from biogenesis to fusion. J Neurochem 2016; 137:904-12. [PMID: 26877188 DOI: 10.1111/jnc.13577] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 01/20/2016] [Accepted: 02/03/2016] [Indexed: 01/01/2023]
Abstract
The regulated secretory pathway begins with the formation of secretory granules by budding from the Golgi apparatus and ends by their fusion with the plasma membrane leading to the release of their content into the extracellular space, generally following a rise in cytosolic calcium. Generation of these membrane-bound transport carriers can be classified into three steps: (i) cargo sorting that segregates the cargo from resident proteins of the Golgi apparatus, (ii) membrane budding that encloses the cargo and depends on the creation of appropriate membrane curvature, and (iii) membrane fission events allowing the nascent carrier to separate from the donor membrane. These secretory vesicles then mature as they are actively transported along microtubules toward the cortical actin network at the cell periphery. The final stage known as regulated exocytosis involves the docking and the priming of the mature granules, necessary for merging of vesicular and plasma membranes, and the subsequent partial or total release of the secretory vesicle content. Here, we review the latest evidence detailing the functional roles played by lipids during secretory granule biogenesis, recruitment, and exocytosis steps. In this review, we highlight evidence supporting the notion that lipids play important functions in secretory vesicle biogenesis, maturation, recruitment, and membrane fusion steps. These effects include regulating various protein distribution and activity, but also directly modulating membrane topology. The challenges ahead to understand the pleiotropic functions of lipids in a secretory granule's journey are also discussed. This article is part of a mini review series on Chromaffin cells (ISCCB Meeting, 2015).
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Affiliation(s)
- Emeline Tanguy
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique & Université de Strasbourg, Strasbourg, France
| | - Ophélie Carmon
- INSERM U982, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale, Université de Rouen, Mont-Saint-Aignan, France
| | - Qili Wang
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique & Université de Strasbourg, Strasbourg, France
| | - Lydie Jeandel
- INSERM U982, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale, Université de Rouen, Mont-Saint-Aignan, France
| | - Sylvette Chasserot-Golaz
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique & Université de Strasbourg, Strasbourg, France
| | - Maité Montero-Hadjadje
- INSERM U982, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale, Université de Rouen, Mont-Saint-Aignan, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique & Université de Strasbourg, Strasbourg, France
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21
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Musinova YR, Sheval EV, Dib C, Germini D, Vassetzky YS. Functional roles of HIV-1 Tat protein in the nucleus. Cell Mol Life Sci 2016; 73:589-601. [PMID: 26507246 PMCID: PMC11108392 DOI: 10.1007/s00018-015-2077-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 09/01/2015] [Accepted: 10/16/2015] [Indexed: 02/06/2023]
Abstract
Human immunodeficiency virus-1 (HIV-1) Tat protein is one of the most important regulatory proteins for viral gene expression in the host cell and can modulate different cellular processes. In addition, Tat is secreted by the infected cell and can be internalized by neighboring cells; therefore, it affects both infected and uninfected cells. Tat can modulate cellular processes by interacting with different cellular structures and signaling pathways. In the nucleus, Tat might be localized either in the nucleoplasm or the nucleolus depending on its concentration. Here we review the distinct functions of Tat in the nucleoplasm and the nucleolus in connection with viral infection and HIV-induced oncogenesis.
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Affiliation(s)
- Yana R Musinova
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, 119991, Moscow, Russia
- LIA 1066 French-Russian Joint Cancer Research Laboratory, 94805, Villejuif, France
| | - Eugene V Sheval
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, 119991, Moscow, Russia
- LIA 1066 French-Russian Joint Cancer Research Laboratory, 94805, Villejuif, France
| | - Carla Dib
- LIA 1066 French-Russian Joint Cancer Research Laboratory, 94805, Villejuif, France
- UMR8126, Université Paris-Sud, CNRS, Institut de cancérologie Gustave Roussy, 94805, Villejuif, France
| | - Diego Germini
- LIA 1066 French-Russian Joint Cancer Research Laboratory, 94805, Villejuif, France
- UMR8126, Université Paris-Sud, CNRS, Institut de cancérologie Gustave Roussy, 94805, Villejuif, France
| | - Yegor S Vassetzky
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, 119991, Moscow, Russia.
- LIA 1066 French-Russian Joint Cancer Research Laboratory, 94805, Villejuif, France.
- UMR8126, Université Paris-Sud, CNRS, Institut de cancérologie Gustave Roussy, 94805, Villejuif, France.
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22
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HIV-1 Tat inhibits phagocytosis by preventing the recruitment of Cdc42 to the phagocytic cup. Nat Commun 2015; 6:6211. [PMID: 25648615 DOI: 10.1038/ncomms7211] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 01/06/2015] [Indexed: 11/08/2022] Open
Abstract
Most macrophages remain uninfected in HIV-1-infected patients. Nevertheless, the phagocytic capacity of phagocytes from these patients is impaired, favouring the multiplication of opportunistic pathogens. The basis for this phagocytic defect is not known. HIV-1 Tat protein is efficiently secreted by infected cells. Secreted Tat can enter uninfected cells and reach their cytosol. Here we found that extracellular Tat, at the subnanomolar concentration present in the sera of HIV-1-infected patients, inhibits the phagocytosis of Mycobacterium avium or opsonized Toxoplasma gondii by human primary macrophages. This inhibition results from a defect in mannose- and Fcγ-receptor-mediated phagocytosis, respectively. Inhibition relies on the interaction of Tat with phosphatidylinositol (4,5)bisphosphate that interferes with the recruitment of Cdc42 to the phagocytic cup, thereby preventing Cdc42 activation and pseudopod elongation. Tat also inhibits FcγR-mediated phagocytosis in neutrophils and monocytes. This study provides a molecular basis for the phagocytic defects observed in uninfected phagocytes following HIV-1 infection.
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23
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Bagashev A, Mukerjee R, Santerre M, Del Carpio-Cano FE, Shrestha J, Wang Y, He JJ, Sawaya BE. Involvement of miR-196a in HIV-associated neurocognitive disorders. Apoptosis 2015; 19:1202-14. [PMID: 24872081 DOI: 10.1007/s10495-014-1003-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Involvement of the human immunodeficiency virus type 1 (HIV-1) trans-activator of transcription (Tat) protein in neuronal deregulation and in the development of HIV-1 associated neurocognitive disorders (HAND) has been amply explored; however the mechanisms involved remain unclear. In search for the mechanisms, we demonstrated that Tat deregulates neuronal functions through a pathway that involved p73 and p53 pathway. We showed that Tat uses microRNA-196a (miR-196a) to deregulate the p73 pathway. Further, we found that the Abelson murine leukemia (c-Abl) phosphorylates p73 on tyrosine residue 99 (Tyr-99) in Tat-treated cells. Interestingly, Tat lost its ability to promote accumulation and phosphorylation of p73 in the presence of miR-196a mimic. Interestingly, accumulation of p73 did not lead to neuronal cell death by apoptosis as obtained by cell viability assay. Western blot analysis using antibodies directed against serine residues 807 and 811 of retinoblastoma (Rb) protein was also used to validate our data regarding lack of cell death. Hyperphosphorylation of RB (S807/811) is an indication of cell neuronal viability. These results highlight the key role played by p73 and microRNA in Tat-treated neurons leading to their deregulation and it deciphers mechanistically one of the pathways used by Tat to cause neuronal dysfunction that contributes to the development of HAND.
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Affiliation(s)
- Asen Bagashev
- Molecular Studies of Neurodegenerative Diseases Lab, FELS Institute for Cancer Research & Molecular Biology, Temple University School of Medicine, PHA # 302, 3307 North Broad Street, Philadelphia, PA, 19140, USA
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24
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Martin TFJ. PI(4,5)P₂-binding effector proteins for vesicle exocytosis. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1851:785-93. [PMID: 25280637 DOI: 10.1016/j.bbalip.2014.09.017] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/20/2014] [Accepted: 09/23/2014] [Indexed: 12/27/2022]
Abstract
PI(4,5)P₂participates directly in priming and possibly in fusion steps of Ca²⁺-triggered vesicle exocytosis. High concentration nanodomains of PI(4,5)P₂reside on the plasma membrane of neuroendocrine cells. A subset of vesicles that co-localize with PI(4,5)P₂ domains appear to undergo preferential exocytosis in stimulated cells. PI(4,5)P₂directly regulates vesicle exocytosis by recruiting and activating PI(4,5)P₂-binding proteins that regulate SNARE protein function including CAPS, Munc13-1/2, synaptotagmin-1, and other C2 domain-containing proteins. These PI(4,5)P₂effector proteins are coincidence detectors that engage in multiple interactions at vesicle exocytic sites. The SNARE protein syntaxin-1 also binds to PI(4,5)P₂, which promotes clustering, but an activating role for PI(4,5)P₂in syntaxin-1 function remains to be fully characterized. Similar principles underlie polarized constitutive vesicle fusion mediated in part by the PI(4,5)P₂-binding subunits of the exocyst complex (Sec3, Exo70). Overall, focal vesicle exocytosis occurs at sites landmarked by PI(4,5)P2, which serves to recruit and/or activate multifunctional PI(4,5)P₂-binding proteins. This article is part of a Special Issue entitled Phosphoinositides.
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Affiliation(s)
- Thomas F J Martin
- Biochemistry Department, University of Wisconsin, 433 Babcock Drive, Madison, WI 53706, USA.
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25
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Paris JJ, Singh HD, Ganno ML, Jackson P, McLaughlin JP. Anxiety-like behavior of mice produced by conditional central expression of the HIV-1 regulatory protein, Tat. Psychopharmacology (Berl) 2014; 231:2349-60. [PMID: 24352568 PMCID: PMC4020990 DOI: 10.1007/s00213-013-3385-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 11/30/2013] [Indexed: 10/25/2022]
Abstract
RATIONALE Human immunodeficiency virus (HIV) infection is associated with substantial increases in generalized anxiety. The HIV regulatory protein, transactivator of transcription (Tat), has been implicated in the neuropathogenesis related to HIV-1 infection. However, direct examination of the effect of Tat on behavioral measures of anxiety has not been demonstrated. OBJECTIVE To identify whether expression of the Tat1-86 protein exerts dose-dependent and persistent anxiety-like effects in a whole animal model, the GT-tg bigenic mouse. METHODS GT-tg mice and C57BL/6J controls were administered doxycycline in a dose- (0, 50, 100, or 125 mg/kg, i.p., for 7 days) or duration- (100 mg/kg, i.p., for 0, 1, 3, 5, or 14 days) dependent manner to induce Tat1-86 in brain. Mice were assessed for anxiety-like behavior in an open field, social interaction, or marble burying task 0, 7, and/or 14 days later. Central expression of Tat1-86 protein was verified with Western blot analyses. RESULTS Doxycycline produced no effects on C57BL/6J controls that lacked the Tat1-86 transgene. Among GT-tg mice, doxycycline (100 mg/kg for 3, 5, or 7 days) significantly increased anxiety-like behavior in all tasks, commensurate with enhanced Western blot labeling of Tat1-86 protein in brain, displaying optimal effects with the 7-day regimen. Greater exposure to doxycycline (either 125 mg/kg for 7 days or 100 mg/kg for 14 days) impaired locomotor behavior; whereas lower dosing (below 100 mg/kg) produced only transient increases in anxiety-like behavior. CONCLUSIONS Expression of HIV-1-Tat1-86 in GT-tg mouse brain produces exposure-dependent, persistent increases in anxiety-like behavior.
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Affiliation(s)
- Jason J. Paris
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port Saint Lucie, FL 34987, USA
| | - Harminder D. Singh
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port Saint Lucie, FL 34987, USA
| | - Michelle L. Ganno
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port Saint Lucie, FL 34987, USA
| | - Pauline Jackson
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port Saint Lucie, FL 34987, USA
| | - Jay P. McLaughlin
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port Saint Lucie, FL 34987, USA,Contact for Correspondence: Jay P. McLaughlin, Ph.D., Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port Saint Lucie, FL 34987, USA, Phone: +1 772-345-4715, Fax: +1 772-345-3649,
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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] [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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27
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Papadopulos A, Tomatis VM, Kasula R, Meunier FA. The cortical acto-Myosin network: from diffusion barrier to functional gateway in the transport of neurosecretory vesicles to the plasma membrane. Front Endocrinol (Lausanne) 2013; 4:153. [PMID: 24155741 PMCID: PMC3800816 DOI: 10.3389/fendo.2013.00153] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 10/05/2013] [Indexed: 01/14/2023] Open
Abstract
Dysregulation of regulated exocytosis is linked to an array of pathological conditions, including neurodegenerative disorders, asthma, and diabetes. Understanding the molecular mechanisms underpinning neuroexocytosis including the processes that allow neurosecretory vesicles to access and fuse with the plasma membrane and to recycle post-fusion, is therefore critical to the design of future therapeutic drugs that will efficiently tackle these diseases. Despite considerable efforts to determine the principles of vesicular fusion, the mechanisms controlling the approach of vesicles to the plasma membrane in order to undergo tethering, docking, priming, and fusion remain poorly understood. All these steps involve the cortical actin network, a dense mesh of actin filaments localized beneath the plasma membrane. Recent work overturned the long-held belief that the cortical actin network only plays a passive constraining role in neuroexocytosis functioning as a physical barrier that partly breaks down upon entry of Ca(2+) to allow secretory vesicles to reach the plasma membrane. A multitude of new roles for the cortical actin network in regulated exocytosis have now emerged and point to highly dynamic novel functions of key myosin molecular motors. Myosins are not only believed to help bring about dynamic changes in the actin cytoskeleton, tethering and guiding vesicles to their fusion sites, but they also regulate the size and duration of the fusion pore, thereby directly contributing to the release of neurotransmitters and hormones. Here we discuss the functions of the cortical actin network, myosins, and their effectors in controlling the processes that lead to tethering, directed transport, docking, and fusion of exocytotic vesicles in regulated exocytosis.
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Affiliation(s)
- Andreas Papadopulos
- Queensland Brain Institute, The University of Queensland, St Lucia Campus, Brisbane, QLD, Australia
| | - Vanesa M. Tomatis
- Queensland Brain Institute, The University of Queensland, St Lucia Campus, Brisbane, QLD, Australia
| | - Ravikiran Kasula
- Queensland Brain Institute, The University of Queensland, St Lucia Campus, Brisbane, QLD, Australia
| | - Frederic A. Meunier
- Queensland Brain Institute, The University of Queensland, St Lucia Campus, Brisbane, QLD, Australia
- *Correspondence: Frederic A. Meunier, Queensland Brain Institute, The University of Queensland, St Lucia Campus, QBI Building #79, St Lucia, QLD 4072, Australia e-mail:
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Ammar MR, Kassas N, Chasserot-Golaz S, Bader MF, Vitale N. Lipids in Regulated Exocytosis: What are They Doing? Front Endocrinol (Lausanne) 2013; 4:125. [PMID: 24062727 PMCID: PMC3775428 DOI: 10.3389/fendo.2013.00125] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 08/31/2013] [Indexed: 12/27/2022] Open
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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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] [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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