1
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Bailly C, Degand C, Laine W, Sauzeau V, Kluza J. Implication of Rac1 GTPase in molecular and cellular mitochondrial functions. Life Sci 2024; 342:122510. [PMID: 38387701 DOI: 10.1016/j.lfs.2024.122510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 02/07/2024] [Accepted: 02/16/2024] [Indexed: 02/24/2024]
Abstract
Rac1 is a member of the Rho GTPase family which plays major roles in cell mobility, polarity and migration, as a fundamental regulator of actin cytoskeleton. Signal transduction by Rac1 occurs through interaction with multiple effector proteins, and its activity is regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). The small protein is mainly anchored to the inner side of the plasma membrane but it can be found in endocellular compartments, notably endosomes and cell nuclei. The protein localizes also into mitochondria where it contributes to the regulation of mitochondrial dynamics, including both mitobiogenesis and mitophagy, in addition to signaling processes via different protein partners, such as the proapoptotic protein Bcl-2 and chaperone sigma-1 receptor (σ-1R). The mitochondrial form of Rac1 (mtRac1) has been understudied thus far, but it is as essential as the nuclear or plasma membrane forms, via its implication in regulation of oxidative stress and DNA damages. Rac1 is subject to diverse post-translational modifications, notably to a geranylgeranylation which contributes importantly to its mitochondrial import and its anchorage to mitochondrial membranes. In addition, Rac1 contributes to the mitochondrial translocation of other proteins, such as p53. The mitochondrial localization and functions of Rac1 are discussed here, notably in the context of human diseases such as cancers. Inhibitors of Rac1 have been identified (NSC-23766, EHT-1864) and some are being developed for the treatment of cancer (MBQ-167) or central nervous system diseases (JK-50561). Their effects on mtRac1 warrant further investigations. An overview of mtRac1 is provided here.
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Affiliation(s)
- Christian Bailly
- University of Lille, CNRS, Inserm, CHU Lille, UMR9020 - UMR1277 - Canther - Cancer Heterogeneity, Plasticity and Resistance to Therapies, 59000 Lille, France; University of Lille, Faculty of Pharmacy, Institut de Chimie Pharmaceutique Albert Lespagnol (ICPAL), 3 rue du Professeur Laguesse, 59000 Lille, France; OncoWitan, Consulting Scientific Office, Lille (Wasquehal) 59290, France.
| | - Claire Degand
- University of Lille, CNRS, Inserm, CHU Lille, UMR9020 - UMR1277 - Canther - Cancer Heterogeneity, Plasticity and Resistance to Therapies, 59000 Lille, France
| | - William Laine
- University of Lille, CNRS, Inserm, CHU Lille, UMR9020 - UMR1277 - Canther - Cancer Heterogeneity, Plasticity and Resistance to Therapies, 59000 Lille, France
| | - Vincent Sauzeau
- Université de Nantes, CHU Nantes, CNRS, INSERM, Institut du thorax, Nantes, France
| | - Jérôme Kluza
- University of Lille, CNRS, Inserm, CHU Lille, UMR9020 - UMR1277 - Canther - Cancer Heterogeneity, Plasticity and Resistance to Therapies, 59000 Lille, France
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2
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Capitani N, Baldari CT. F-Actin Dynamics in the Regulation of Endosomal Recycling and Immune Synapse Assembly. Front Cell Dev Biol 2021; 9:670882. [PMID: 34249926 PMCID: PMC8265274 DOI: 10.3389/fcell.2021.670882] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 05/24/2021] [Indexed: 12/24/2022] Open
Abstract
Membrane proteins endocytosed at the cell surface as vesicular cargoes are sorted at early endosomes for delivery to lysosomes for degradation or alternatively recycled to different cellular destinations. Cargo recycling is orchestrated by multimolecular complexes that include the retromer, retriever, and the WASH complex, which promote the polymerization of new actin filaments at early endosomes. These endosomal actin pools play a key role at different steps of the recycling process, from cargo segregation to specific endosomal subdomains to the generation and mobility of tubulo-vesicular transport carriers. Local F-actin pools also participate in the complex redistribution of endomembranes and organelles that leads to the acquisition of cell polarity. Here, we will present an overview of the contribution of endosomal F-actin to T-cell polarization during assembly of the immune synapse, a specialized membrane domain that T cells form at the contact with cognate antigen-presenting cells.
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Affiliation(s)
- Nagaja Capitani
- Department of Life Sciences, University of Siena, Siena, Italy
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3
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Erasmus JC, Smolarczyk K, Brezovjakova H, Mohd-Naim NF, Lozano E, Matter K, Braga VMM. Rac1-PAK1 regulation of Rab11 cycling promotes junction destabilization. J Cell Biol 2021; 220:212034. [PMID: 33914026 PMCID: PMC8091128 DOI: 10.1083/jcb.202002114] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 09/21/2020] [Accepted: 02/04/2021] [Indexed: 12/12/2022] Open
Abstract
Rac1 GTPase is hyperactivated in tumors and contributes to malignancy. Rac1 disruption of junctions requires its effector PAK1, but the precise mechanisms are unknown. Here, we show that E-cadherin is internalized via micropinocytosis in a PAK1–dependent manner without catenin dissociation and degradation. In addition to internalization, PAK1 regulates E-cadherin transport by fine-tuning Rab small GTPase function. PAK1 phosphorylates a core Rab regulator, RabGDIβ, but not RabGDIα. Phosphorylated RabGDIβ preferentially associates with Rab5 and Rab11, which is predicted to promote Rab retrieval from membranes. Consistent with this hypothesis, Rab11 is activated by Rac1, and inhibition of Rab11 function partially rescues E-cadherin destabilization. Thus, Rac1 activation reduces surface cadherin levels as a net result of higher bulk flow of membrane uptake that counteracts Rab11-dependent E-cadherin delivery to junctions (recycling and/or exocytosis). This unique small GTPase crosstalk has an impact on Rac1 and PAK1 regulation of membrane remodeling during epithelial dedifferentiation, adhesion, and motility.
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Affiliation(s)
- Jennifer C Erasmus
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK
| | - Kasia Smolarczyk
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK
| | - Helena Brezovjakova
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK
| | - Noor F Mohd-Naim
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK
| | - Encarnación Lozano
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK
| | - Karl Matter
- Institute of Ophthalmology, University College London, London, UK
| | - Vania M M Braga
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK
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4
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Mastrogiovanni M, Juzans M, Alcover A, Di Bartolo V. Coordinating Cytoskeleton and Molecular Traffic in T Cell Migration, Activation, and Effector Functions. Front Cell Dev Biol 2020; 8:591348. [PMID: 33195256 PMCID: PMC7609836 DOI: 10.3389/fcell.2020.591348] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 09/24/2020] [Indexed: 12/28/2022] Open
Abstract
Dynamic localization of receptors and signaling molecules at the plasma membrane and within intracellular vesicular compartments is crucial for T lymphocyte sensing environmental cues, triggering membrane receptors, recruiting signaling molecules, and fine-tuning of intracellular signals. The orchestrated action of actin and microtubule cytoskeleton and intracellular vesicle traffic plays a key role in all these events that together ensure important steps in T cell physiology. These include extravasation and migration through lymphoid and peripheral tissues, T cell interactions with antigen-presenting cells, T cell receptor (TCR) triggering by cognate antigen–major histocompatibility complex (MHC) complexes, immunological synapse formation, cell activation, and effector functions. Cytoskeletal and vesicle traffic dynamics and their interplay are coordinated by a variety of regulatory molecules. Among them, polarity regulators and membrane–cytoskeleton linkers are master controllers of this interplay. Here, we review the various ways the T cell plasma membrane, receptors, and their signaling machinery interplay with the actin and microtubule cytoskeleton and with intracellular vesicular compartments. We highlight the importance of this fine-tuned crosstalk in three key stages of T cell biology involving cell polarization: T cell migration in response to chemokines, immunological synapse formation in response to antigen cues, and effector functions. Finally, we discuss two examples of perturbation of this interplay in pathological settings, such as HIV-1 infection and mutation of the polarity regulator and tumor suppressor adenomatous polyposis coli (Apc) that leads to familial polyposis and colorectal cancer.
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Affiliation(s)
- Marta Mastrogiovanni
- Ligue Nationale Contre le Cancer - Equipe Labellisée LIGUE 2018, Lymphocyte Cell Biology Unit, INSERM-U1221, Department of Immunology, Institut Pasteur, Paris, France.,Collège Doctoral, Sorbonne Université, Paris, France
| | - Marie Juzans
- Ligue Nationale Contre le Cancer - Equipe Labellisée LIGUE 2018, Lymphocyte Cell Biology Unit, INSERM-U1221, Department of Immunology, Institut Pasteur, Paris, France
| | - Andrés Alcover
- Ligue Nationale Contre le Cancer - Equipe Labellisée LIGUE 2018, Lymphocyte Cell Biology Unit, INSERM-U1221, Department of Immunology, Institut Pasteur, Paris, France
| | - Vincenzo Di Bartolo
- Ligue Nationale Contre le Cancer - Equipe Labellisée LIGUE 2018, Lymphocyte Cell Biology Unit, INSERM-U1221, Department of Immunology, Institut Pasteur, Paris, France
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5
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Wang X, Weng M, Ke Y, Sapp E, DiFiglia M, Li X. Kalirin Interacts with TRAPP and Regulates Rab11 and Endosomal Recycling. Cells 2020; 9:cells9051132. [PMID: 32375403 PMCID: PMC7291072 DOI: 10.3390/cells9051132] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/24/2020] [Accepted: 05/01/2020] [Indexed: 12/21/2022] Open
Abstract
Coordinated actions of Rab and Rho are necessary for numerous essential cellular processes ranging from vesicle budding to whole cell movement. How Rab and Rho are choreographed is poorly understood. Here, we report a protein complex comprised of kalirin, a Rho guanine nucleotide exchange factor (GEF) activating Rac1, and RabGEF transport protein particle (TRAPP). Kalirin was identified in a mass spectrometry analysis of proteins precipitated by trappc4 and detected on membranous organelles containing trappc4. Acute knockdown of kalirin did not affect trappc4, but significantly reduced overall and membrane-bound levels of trappc9, which specifies TRAPP toward activating Rab11. Trappc9 deficiency led to elevated expression of kalirin in neurons. Co-localization of kalirin and Rab11 occurred at a low frequency in NRK cells under steady state and was enhanced upon expressing an inactive Rab11 mutant to prohibit the dissociation of Rab11 from the kalirin-TRAPP complex. The small RNA-mediated depletion of kalirin diminished activities in cellular membranes for activating Rab11 and resulted in a shift in size of Rab11 positive structures from small to larger ones and tubulation of recycling endosomes. Our study suggests that kalirin and TRAPP form a dual GEF complex to choreograph actions of Rab11 and Rac1 at recycling endosomes.
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Affiliation(s)
- Xiaolong Wang
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai 200240, China; (X.W.); (Y.K.)
| | - Meiqian Weng
- Mucosal Immunology Lab combined program in Pediatric Gastroenterology and Nutrition, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA;
| | - Yuting Ke
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai 200240, China; (X.W.); (Y.K.)
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; (E.S.); (M.D.)
| | - Ellen Sapp
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; (E.S.); (M.D.)
| | - Marian DiFiglia
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; (E.S.); (M.D.)
| | - Xueyi Li
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai 200240, China; (X.W.); (Y.K.)
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; (E.S.); (M.D.)
- Correspondence: or ; Tel.: +86-21-34204737
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6
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Li F, Du W, Wang H, Zhao S, Zhu L, Hao J. Activation of AMPK pathway compromises Rab11 downregulation-mediated inhibition of Schwann cell proliferation in a Glut1 and Glut3-dependent manner. Neurosci Lett 2020; 720:134762. [PMID: 31954765 DOI: 10.1016/j.neulet.2020.134762] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/26/2019] [Accepted: 01/14/2020] [Indexed: 12/17/2022]
Abstract
Rab11, a small GTPase, is an important protein in the regulation of intracellular plasma membrane trafficking. Schwann cells are the main cells of peripheral nerves and knockdown of Rab11 in these cells inhibits the formation of functional tunneling nanotubes (TNTs). However, the role of Rab11 in the functioning of Schwann cells remains elusive. Herein, using cell viability analysis, live/dead cell staining, BrdU assay, and western blot analysis with an AMPK antibody, we observed that the knockdown of Rab11 significantly inhibited the proliferation of RSC96 cells. Further investigations showed that the AMPK pathway was activated by the knockdown of Rab11, as indicated by the enhanced levels of phosphorylated AMPK. Moreover, suppression of AMPK pathway with Compound C aggravated Rab11 knockdown-induced inhibition of cell proliferation. In contrast, activation of the AMPK pathway with AICAR ameliorated the Rab11 knockdown-mediated inhibition of cell proliferation. Furthermore, the levels of Glut1 and Glut3 were decreased in the RSC96 cells upon Rab11 knockdown. Additionally, the knockdown of Glut1 and Glut3 led to the activation of the AMPK pathway in RSC96 cells. We conclude that the knockdown of Rab11 suppresses the proliferation of RSC96 cells, and as a compensatory mechanism, the activation of AMPK pathway, in a Glut1 and Glut3-dependent manner, improves RSC96 cell proliferation.
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Affiliation(s)
- Fan Li
- Department of Pathology, Hebei Medical University, Shijiazhuang, China; Center of Metabolic Diseases and Cancer Research, Institute of Medical and Health Science of Hebei Medical University, Shijiazhuang, China
| | - Wei Du
- Department of Pathology, Hebei Medical University, Shijiazhuang, China; Center of Metabolic Diseases and Cancer Research, Institute of Medical and Health Science of Hebei Medical University, Shijiazhuang, China
| | - Hui Wang
- Department of Pathology, Hebei Medical University, Shijiazhuang, China; Center of Metabolic Diseases and Cancer Research, Institute of Medical and Health Science of Hebei Medical University, Shijiazhuang, China
| | - Song Zhao
- Department of Pathology, Hebei Medical University, Shijiazhuang, China; Center of Metabolic Diseases and Cancer Research, Institute of Medical and Health Science of Hebei Medical University, Shijiazhuang, China
| | - Lin Zhu
- Department of Electromyogram, the Third Hospital of Hebei Medical University, Shijiazhuang, China.
| | - Jun Hao
- Department of Pathology, Hebei Medical University, Shijiazhuang, China; Center of Metabolic Diseases and Cancer Research, Institute of Medical and Health Science of Hebei Medical University, Shijiazhuang, China
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7
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Saraste J, Prydz K. A New Look at the Functional Organization of the Golgi Ribbon. Front Cell Dev Biol 2019; 7:171. [PMID: 31497600 PMCID: PMC6713163 DOI: 10.3389/fcell.2019.00171] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 08/07/2019] [Indexed: 12/14/2022] Open
Abstract
A characteristic feature of vertebrate cells is a Golgi ribbon consisting of multiple cisternal stacks connected into a single-copy organelle next to the centrosome. Despite numerous studies, the mechanisms that link the stacks together and the functional significance of ribbon formation remain poorly understood. Nevertheless, these questions are of considerable interest, since there is increasing evidence that Golgi fragmentation – the unlinking of the stacks in the ribbon – is intimately connected not only to normal physiological processes, such as cell division and migration, but also to pathological states, including neurodegeneration and cancer. Challenging a commonly held view that ribbon architecture involves the formation of homotypic tubular bridges between the Golgi stacks, we present an alternative model, based on direct interaction between the biosynthetic (pre-Golgi) and endocytic (post-Golgi) membrane networks and their connection with the centrosome. We propose that the central domains of these permanent pre- and post-Golgi networks function together in the biogenesis and maintenance of the more transient Golgi stacks, and thereby establish “linker compartments” that dynamically join the stacks together. This model provides insight into the reversible fragmentation of the Golgi ribbon that takes place in dividing and migrating cells and its regulation along a cell surface – Golgi – centrosome axis. Moreover, it helps to understand transport pathways that either traverse or bypass the Golgi stacks and the positioning of the Golgi apparatus in differentiated neuronal, epithelial, and muscle cells.
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Affiliation(s)
- Jaakko Saraste
- Department of Biomedicine and Molecular Imaging Center, University of Bergen, Bergen, Norway
| | - Kristian Prydz
- Department of Biosciences, University of Oslo, Oslo, Norway
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8
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Onnis A, Baldari CT. Orchestration of Immunological Synapse Assembly by Vesicular Trafficking. Front Cell Dev Biol 2019; 7:110. [PMID: 31334230 PMCID: PMC6616304 DOI: 10.3389/fcell.2019.00110] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 06/03/2019] [Indexed: 12/15/2022] Open
Abstract
Ligation of the T-cell antigen receptor (TCR) by cognate peptide bound to the Major Histocompatibility Complex on the surface of an antigen-presenting cell (APC) leads to the spatial reorganization of the TCR and accessory receptors to form a specialized area of intimate contact between T cell and APC, known as the immunological synapse (IS), where signals are deciphered, coordinated, and integrated to promote T cell activation. With the discovery that an endosomal TCR pool contributes to IS assembly and function by undergoing polarized recycling to the IS, recent years have witnessed a shift from a plasma membrane-centric view of the IS to the vesicular trafficking events that occur at this location following the TCR-dependent translocation of the centrosome toward the synaptic membrane. Here we will summarize our current understanding of the trafficking pathways that are responsible for the steady delivery of endosomal TCRs, kinases, and adapters to the IS to sustain signaling, as well as of the endocytic pathways responsible for signal termination. We will also discuss recent evidence highlighting a role for endosomes in sustaining TCR signaling after its internalization at the IS and identifying the IS as a site of formation and release of extracellular vesicles that allow for transcellular communication with the APC.
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Affiliation(s)
- Anna Onnis
- Department of Life Sciences, University of Siena, Siena, Italy
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9
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Castro-Sánchez P, Ramirez-Munoz R, Martín-Cófreces NB, Aguilar-Sopeña O, Alegre-Gomez S, Hernández-Pérez S, Reyes R, Zeng Q, Cabañas C, Sánchez-Madrid F, Roda-Navarro P. Phosphatase of Regenerating Liver-1 (PRL-1) Regulates Actin Dynamics During Immunological Synapse Assembly and T Cell Effector Function. Front Immunol 2018; 9:2655. [PMID: 30515156 PMCID: PMC6255827 DOI: 10.3389/fimmu.2018.02655] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Accepted: 10/29/2018] [Indexed: 12/30/2022] Open
Abstract
The regulatory role of most dual specific phosphatases during T cell activation remains unknown. Here, we have studied the expression and function of phosphatases of regenerating liver (PRLs: PRL-1, PRL-2, and PRL-3) during T cell activation, as well as, the dynamic delivery of PRL-1 to the Immunological Synapse (IS). We found that T cell activation downregulates the expression of PRL-2, resulting in an increased PRL-1/PRL-2 ratio. PRL-1 redistributed at the IS in two stages: Initially, it was transiently accumulated at scanning membranes enriched in CD3 and actin, and at later times, it was delivered at the contact site from pericentriolar, CD3ζ-containing, vesicles. Once at the established IS, PRL-1 distributed to LFA-1 and CD3ε sites. Remarkably, PRL-1 was found to regulate actin dynamics during IS assembly and the secretion of IL-2. Moreover, pharmacological inhibition of the catalytic activity of the three PRLs reduced the secretion of IL-2. These results provide evidence indicating a regulatory role of PRL-1 during IS assembly and highlight the involvement of PRLs in immune responses by mature T cells.
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Affiliation(s)
- Patricia Castro-Sánchez
- Department of Immunology, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain.,12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Rocío Ramirez-Munoz
- Department of Immunology, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain.,12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Noa B Martín-Cófreces
- Servicio de Inmunología. Hospital Universitario de la Princesa, Universidad Autónoma de Madrid, Instituto de Investigación Sanitaria Princesa (IP), Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - Oscar Aguilar-Sopeña
- Department of Immunology, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain.,12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Sergio Alegre-Gomez
- Department of Immunology, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain.,12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Sara Hernández-Pérez
- Department of Immunology, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain.,12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Raquel Reyes
- Department of Cell Biology and Immunology, Center for Molecular Biology Severo Ochoa (CBM-SO), Mayor Council of Scientific Research (CSIC), Madrid, Spain
| | - Qi Zeng
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (ASTAR), Singapore, Singapore
| | - Carlos Cabañas
- Department of Immunology, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain.,12 de Octubre Health Research Institute (imas12), Madrid, Spain.,Department of Cell Biology and Immunology, Center for Molecular Biology Severo Ochoa (CBM-SO), Mayor Council of Scientific Research (CSIC), Madrid, Spain
| | - Francisco Sánchez-Madrid
- Servicio de Inmunología. Hospital Universitario de la Princesa, Universidad Autónoma de Madrid, Instituto de Investigación Sanitaria Princesa (IP), Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - Pedro Roda-Navarro
- Department of Immunology, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain.,12 de Octubre Health Research Institute (imas12), Madrid, Spain
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10
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Iyer S, Subramanian V, Acharya KR. C9orf72, a protein associated with amyotrophic lateral sclerosis (ALS) is a guanine nucleotide exchange factor. PeerJ 2018; 6:e5815. [PMID: 30356970 PMCID: PMC6195791 DOI: 10.7717/peerj.5815] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 09/22/2018] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), two late onset neurodegenerative diseases, have been shown to share overlapping cellular pathologies and genetic origins. Studies suggest that a hexanucleotide repeat expansion in the first intron of the C9orf72 gene is the most common cause of familial FTD and ALS pathology. The C9orf72 protein is predicted to be a differentially expressed in normal and neoplastic cells domain protein implying that C9orf72 functions as a guanine nucleotide exchange factor (GEF) to regulate specific Rab GTPases. Reported studies thus far point to a putative role for C9orf72 in lysosome biogenesis, vesicular trafficking, autophagy and mechanistic target of rapamycin complex1 (mTORC1) signaling. Here we report the expression, purification and biochemical characterization of C9orf72 protein. We conclusively show that C9orf72 is a GEF. The distinctive presence of both Rab- and Rho-GTPase GEF activities suggests that C9orf72 may function as a dual exchange factor coupling physiological functions such as cytoskeleton modulation and autophagy with endocytosis.
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Affiliation(s)
- Shalini Iyer
- Department of Biology and Biochemistry, University of Bath, Bath, UK
| | | | - K Ravi Acharya
- Department of Biology and Biochemistry, University of Bath, Bath, UK
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11
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Del Río-Iñiguez I, Vázquez-Chávez E, Cuche C, Di Bartolo V, Bouchet J, Alcover A. HIV-1 Nef Hijacks Lck and Rac1 Endosomal Traffic To Dually Modulate Signaling-Mediated and Actin Cytoskeleton-Mediated T Cell Functions. THE JOURNAL OF IMMUNOLOGY 2018; 201:2624-2640. [PMID: 30282749 DOI: 10.4049/jimmunol.1800372] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 09/03/2018] [Indexed: 01/03/2023]
Abstract
Endosomal traffic of TCR and signaling molecules regulates immunological synapse formation and T cell activation. We recently showed that Rab11 endosomes regulate the subcellular localization of the tyrosine kinase Lck and of the GTPase Rac1 and control their functions in TCR signaling and actin cytoskeleton remodeling. HIV-1 infection of T cells alters their endosomal traffic, activation capacity, and actin cytoskeleton organization. The viral protein Nef is pivotal for these modifications. We hypothesized that HIV-1 Nef could jointly alter Lck and Rac1 endosomal traffic and concomitantly modulate their functions. In this study, we show that HIV-1 infection of human T cells sequesters both Lck and Rac1 in a pericentrosomal compartment in an Nef-dependent manner. Strikingly, the Nef-induced Lck compartment contains signaling-competent forms (phosphorylated on key Tyr residues) of Lck and some of its downstream effectors, TCRζ, ZAP70, SLP76, and Vav1, avoiding the proximal LAT adaptor. Importantly, Nef-induced concentration of signaling molecules was concomitant with the upregulation of several early and late T cell activation genes. Moreover, preventing the concentration of the Nef-induced Lck compartment by depleting the Rab11 effector FIP3 counteracted Nef-induced gene expression upregulation. In addition, Nef extensively sequesters Rac1 and downregulates Rac1-dependent actin cytoskeleton remodeling, thus reducing T cell spreading. Therefore, by modifying their endosomal traffic, Nef hijacks signaling and actin cytoskeleton regulators to dually modulate their functional outputs. Our data shed new light into the molecular mechanisms that modify T cell physiology during HIV-1 infection.
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Affiliation(s)
- Iratxe Del Río-Iñiguez
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, 75724 Paris, France.,INSERM U1221, 75015 Paris, France; and.,Collège Doctoral, Sorbonne Université, 75014 Paris, France
| | - Elena Vázquez-Chávez
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, 75724 Paris, France.,INSERM U1221, 75015 Paris, France; and
| | - Céline Cuche
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, 75724 Paris, France.,INSERM U1221, 75015 Paris, France; and
| | - Vincenzo Di Bartolo
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, 75724 Paris, France.,INSERM U1221, 75015 Paris, France; and
| | - Jérôme Bouchet
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, 75724 Paris, France; .,INSERM U1221, 75015 Paris, France; and
| | - Andrés Alcover
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, 75724 Paris, France; .,INSERM U1221, 75015 Paris, France; and
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Hernández-González M, Bravo-Plaza I, Pinar M, de los Ríos V, Arst HN, Peñalva MA. Endocytic recycling via the TGN underlies the polarized hyphal mode of life. PLoS Genet 2018; 14:e1007291. [PMID: 29608571 PMCID: PMC5880334 DOI: 10.1371/journal.pgen.1007291] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 03/06/2018] [Indexed: 12/13/2022] Open
Abstract
Intracellular traffic in Aspergillus nidulans hyphae must cope with the challenges that the high rates of apical extension (1μm/min) and the long intracellular distances (>100 μm) impose. Understanding the ways in which the hyphal tip cell coordinates traffic to meet these challenges is of basic importance, but is also of considerable applied interest, as fungal invasiveness of animals and plants depends critically upon maintaining these high rates of growth. Rapid apical extension requires localization of cell-wall-modifying enzymes to hyphal tips. By combining genetic blocks in different trafficking steps with multidimensional epifluorescence microscopy and quantitative image analyses we demonstrate that polarization of the essential chitin-synthase ChsB occurs by indirect endocytic recycling, involving delivery/exocytosis to apices followed by internalization by the sub-apical endocytic collar of actin patches and subsequent trafficking to TGN cisternae, where it accumulates for ~1 min before being re-delivered to the apex by a RAB11/TRAPPII-dependent pathway. Accordingly, ChsB is stranded at the TGN by Sec7 inactivation but re-polarizes to the apical dome if the block is bypassed by a mutation in geaAgea1 that restores growth in the absence of Sec7. That polarization is independent of RAB5, that ChsB predominates at apex-proximal cisternae, and that upon dynein impairment ChsB is stalled at the tips in an aggregated endosome indicate that endocytosed ChsB traffics to the TGN via sorting endosomes functionally located upstream of the RAB5 domain and that this step requires dynein-mediated basipetal transport. It also requires RAB6 and its effector GARP (Vps51/Vps52/Vps53/Vps54), whose composition we determined by MS/MS following affinity chromatography purification. Ablation of any GARP component diverts ChsB to vacuoles and impairs growth and morphology markedly, emphasizing the important physiological role played by this pathway that, we propose, is central to the hyphal mode of growth. Filamentous fungi form long tubular cells, called hyphae, which grow rapidly by apical extension, enabling these sessile organisms to explore substrates and facilitating tissue invasion in the case of pathogenic species. Because the shape of the hyphae is determined by an external cell wall, hyphal growth requires that cell-wall sculpting enzymes polarize to the tips. Endocytosis is essential for hyphal growth, and it was suspected that this results from its participation in a recycling pathway that takes up cell-wall enzymes from the plasma membrane and re-delivers them to the apex. Here we track the trafficking of a chitin synthase (a cell-wall modifying enzyme) to demonstrate that it is polarized by endocytic recycling. This chitin synthase is delivered by exocytosis to the apex, but diffuses away until being captured by a subapical collar of actin patches (sites of endocytosis) from where it reaches a sorting endosome before undergoing transport to the nearest trans-Golgi cisternae and incorporating into secretory vesicles that re-deliver the enzyme to the apex. Because impairing transit across this pathway compromises apical extension markedly and results in severe morphological defects, the pathway could be manipulated to prevent fungal pathogenicity of plants and humans, an enormous burden on human welfare.
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Affiliation(s)
- Miguel Hernández-González
- Department of Cellular and Molecular Biology and Intradepartmental WhiteBiotech Unit, Centro de Investigaciones Biológicas del Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, Madrid, Spain
| | - Ignacio Bravo-Plaza
- Department of Cellular and Molecular Biology and Intradepartmental WhiteBiotech Unit, Centro de Investigaciones Biológicas del Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, Madrid, Spain
| | - Mario Pinar
- Department of Cellular and Molecular Biology and Intradepartmental WhiteBiotech Unit, Centro de Investigaciones Biológicas del Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, Madrid, Spain
| | - Vivian de los Ríos
- Proteomics Facility, Centro de Investigaciones Biológicas del Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, Madrid, Spain
| | - Herbert N. Arst
- Section of Microbiology, Imperial College London, Flowers Building, Armstrong Road, London, United Kingdom
| | - Miguel A. Peñalva
- Department of Cellular and Molecular Biology and Intradepartmental WhiteBiotech Unit, Centro de Investigaciones Biológicas del Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, Madrid, Spain
- * E-mail:
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Abstract
Cell polarity refers to the asymmetric localization of cellular components that allows cells to carry out their specialized functions, be they epithelial barrier function, transmission of action potentials in nerve cells, or modulation of the immune response. The establishment and maintenance of cell polarity requires the directed trafficking of membrane proteins and lipids - essential processes that are mediated by Rab GTPases. Interestingly, several of the Rabs that impact polarity are present in the earliest eukaryotes, and the Rab polarity repertoire has expanded as cells have become more complex. There is a substantial conservation of Rab function across diverse cell types. Rabs act through an assortment of effector proteins that include scaffolding proteins, cytoskeletal motors, and other small GTPases. In this review we highlight the similarities and differences in Rab function for the instruction of polarity in diverse cell types.
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Affiliation(s)
- Sara S Parker
- a Department of Cellular and Molecular Medicine , University of Arizona , Tucson , AZ , USA
| | - Christopher Cox
- a Department of Cellular and Molecular Medicine , University of Arizona , Tucson , AZ , USA
| | - Jean M Wilson
- a Department of Cellular and Molecular Medicine , University of Arizona , Tucson , AZ , USA
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