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Nguyen H, Glaaser IW, Slesinger PA. Direct modulation of G protein-gated inwardly rectifying potassium (GIRK) channels. Front Physiol 2024; 15:1386645. [PMID: 38903913 PMCID: PMC11187414 DOI: 10.3389/fphys.2024.1386645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 04/08/2024] [Indexed: 06/22/2024] Open
Abstract
Ion channels play a pivotal role in regulating cellular excitability and signal transduction processes. Among the various ion channels, G-protein-coupled inwardly rectifying potassium (GIRK) channels serve as key mediators of neurotransmission and cellular responses to extracellular signals. GIRK channels are members of the larger family of inwardly-rectifying potassium (Kir) channels. Typically, GIRK channels are activated via the direct binding of G-protein βγ subunits upon the activation of G-protein-coupled receptors (GPCRs). GIRK channel activation requires the presence of the lipid signaling molecule, phosphatidylinositol 4,5-bisphosphate (PIP2). GIRK channels are also modulated by endogenous proteins and other molecules, including RGS proteins, cholesterol, and SNX27 as well as exogenous compounds, such as alcohol. In the last decade or so, several groups have developed novel drugs and small molecules, such as ML297, GAT1508 and GiGA1, that activate GIRK channels in a G-protein independent manner. Here, we aim to provide a comprehensive overview focusing on the direct modulation of GIRK channels by G-proteins, PIP2, cholesterol, and novel modulatory compounds. These studies offer valuable insights into the underlying molecular mechanisms of channel function, and have potential implications for both basic research and therapeutic development.
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Affiliation(s)
| | | | - Paul A. Slesinger
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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2
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Zambo B, Gogl G, Morlet B, Eberling P, Negroni L, Moine H, Travé G. Comparative analysis of PDZ-binding motifs in the diacylglycerol kinase family. FEBS J 2024; 291:690-704. [PMID: 37942667 DOI: 10.1111/febs.16994] [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: 08/16/2023] [Revised: 09/26/2023] [Accepted: 10/31/2023] [Indexed: 11/10/2023]
Abstract
Diacylglycerol kinases (DGKs) control local and temporal amounts of diacylglycerol (DAG) and phosphatidic acid (PA) by converting DAG to PA through phosphorylation in cells. Certain DGK enzymes possess C-terminal sequences that encode potential PDZ-binding motifs (PBMs), which could be involved in their recruitment into supramolecular signaling complexes. In this study, we used two different interactomic approaches, quantitative native holdup (nHU) and qualitative affinity purification (AP), both coupled to mass spectrometry (MS) to investigate the PDZ partners associated with the potential PBMs of DGKs. Complementing these results with site-specific affinity interactomic data measured on isolated PDZ domain fragments and PBM motifs, as well as evolutionary conservation analysis of the PBMs of DGKs, we explored functional differences within different DGK groups. All our results indicate that putative PBM sequences of type II enzymes, namely DGKδ, DGKη, and DGKκ, are likely to be nonfunctional. In contrast, type IV enzymes, namely DGKζ and DGKι, possess highly promiscuous PBMs that interact with a set of PDZ proteins with very similar affinity interactomes. The combination of various interactomic assays and evolutionary analyses provides a useful strategy for identifying functional domains and motifs within diverse enzyme families.
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Affiliation(s)
- Boglarka Zambo
- Équipe Labellisée Ligue contre le cancer, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U1258/CNRS UMR 7104/Université de Strasbourg, Illkirch, France
| | - Gergo Gogl
- Équipe Labellisée Ligue contre le cancer, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U1258/CNRS UMR 7104/Université de Strasbourg, Illkirch, France
| | - Bastien Morlet
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U1258/CNRS UMR 7104/Université de Strasbourg, Illkirch, France
| | - Pascal Eberling
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U1258/CNRS UMR 7104/Université de Strasbourg, Illkirch, France
| | - Luc Negroni
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U1258/CNRS UMR 7104/Université de Strasbourg, Illkirch, France
| | - Hervé Moine
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U1258/CNRS UMR 7104/Université de Strasbourg, Illkirch, France
| | - Gilles Travé
- Équipe Labellisée Ligue contre le cancer, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U1258/CNRS UMR 7104/Université de Strasbourg, Illkirch, France
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3
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Martin-Salgado M, Ochoa-Echeverría A, Mérida I. Diacylglycerol kinases: A look into the future of immunotherapy. Adv Biol Regul 2024; 91:100999. [PMID: 37949728 DOI: 10.1016/j.jbior.2023.100999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 11/01/2023] [Indexed: 11/12/2023]
Abstract
Cancer still represents the second leading cause of death right after cardiovascular diseases. According to the World Health Organization (WHO), cancer provoked around 10 million deaths in 2020, with lung and colon tumors accounting for the deadliest forms of cancer. As tumor cells become resistant to traditional therapeutic approaches, immunotherapy has emerged as a novel strategy for tumor control. T lymphocytes are key players in immune responses against tumors. Immunosurveillance allows identification, targeting and later killing of cancerous cells. Nevertheless, tumors evolve through different strategies to evade the immune response and spread in a process called metastasis. The ineffectiveness of traditional strategies to control tumor growth and expansion has led to novel approaches considering modulation of T cell activation and effector functions. Program death receptor 1 (PD-1) and cytotoxic T-lymphocyte antigen 4 (CTLA-4) showed promising results in the early 90s and nowadays are still being exploited together with other drugs for several cancer types. Other negative regulators of T cell activation are diacylglycerol kinases (DGKs) a family of enzymes that catalyze the conversion of diacylglycerol (DAG) into phosphatidic acid (PA). In T cells, DGKα and DGKζ limit the PLCγ/Ras/ERK axis thus attenuating DAG mediated signaling and T cell effector functions. Upregulation of either of both isoforms results in impaired Ras activation and anergy induction, whereas germline knockdown mice showed enhanced antitumor properties and more effective immune responses against pathogens. Here we review the mechanisms used by DGKs to ameliorate T cell activation and how inhibition could be used to reinvigorate T cell functions in cancer context. A better knowledge of the molecular mechanisms involved upon T cell activation will help to improve current therapies with DAG promoting agents.
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Affiliation(s)
- Miguel Martin-Salgado
- Department of Immunology and Oncology. National Centre for Biotechnology. Spanish Research Council (CNB-CSIC), Spain
| | - Ane Ochoa-Echeverría
- Department of Immunology and Oncology. National Centre for Biotechnology. Spanish Research Council (CNB-CSIC), Spain
| | - Isabel Mérida
- Department of Immunology and Oncology. National Centre for Biotechnology. Spanish Research Council (CNB-CSIC), Spain.
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4
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Deb S, Sun J. Endosomal Sorting Protein SNX27 and Its Emerging Roles in Human Cancers. Cancers (Basel) 2022; 15:cancers15010070. [PMID: 36612066 PMCID: PMC9818000 DOI: 10.3390/cancers15010070] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/14/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022] Open
Abstract
SNX27 belongs to the sorting nexin (SNX) family of proteins that play a critical role in protein sorting and trafficking in the endocytosis pathway. This protein family is characterized by the presence of a Phox (PX) domain; however, SNX27 is unique in containing an additional PDZ domain. Recently, SNX27 has gained popularity as an important sorting protein that is associated with the retromer complex and mediates the recycling of internalized proteins from endosomes to the plasma membrane in a PDZ domain-dependent manner. Over 100 cell surface proteins have been identified as binding partners of the SNX27-retromer complex. However, the roles and underlying mechanisms governed by SNX27 in tumorigenesis remains to be poorly understood. Many of its known binding partners include several G-protein coupled receptors, such as β2-andrenergic receptor and parathyroid hormone receptor, are associated with multiple pathways implicated in oncogenic signaling and tumorigenesis. Additionally, SNX27 mediates the recycling of GLUT1 and the activation of mTORC1, both of which can regulate intracellular energy balance and promote cell survival and proliferation under conditions of nutrient deprivation. In this review, we summarize the structure and fundamental roles of SNX proteins, with a focus on SNX27, and provide the current evidence indicating towards the role of SNX27 in human cancers. We also discuss the gap in the field and future direction of SNX27 research. Insights into the emerging roles and mechanism of SNX27 in cancers will provide better development strategies to prevent and treat tumorigenesis.
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Affiliation(s)
- Shreya Deb
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Jun Sun
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL 60612, USA
- University of Illinois at Chicago (UIC) Cancer Center, University of Illinois at Chicago, Chicago, IL 60612, USA
- Jesse Brown VA Medical Center, Chicago, IL 60612, USA
- Correspondence: ; Tel.: +1-312-996-5020
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5
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González-Mancha N, Rodríguez-Rodríguez C, Alcover A, Merida I. Sorting Nexin 27 Enables MTOC and Secretory Machinery Translocation to the Immune Synapse. Front Immunol 2022; 12:814570. [PMID: 35095913 PMCID: PMC8790036 DOI: 10.3389/fimmu.2021.814570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 12/20/2021] [Indexed: 11/24/2022] Open
Abstract
Sorting nexin 27 (SNX27) association to the retromer complex mediates intracellular trafficking of cargoes containing PSD95/Dlg1/ZO-1 (PDZ)-binding C-terminal sequences from endosomes to the cell surface, preventing their lysosomal degradation. Antigen recognition by T lymphocyte leads to the formation of a highly organized structure named the immune synapse (IS), which ensures cell-cell communication and sustained T cell activation. At the neuronal synapse, SNX27 recycles PDZ-binding receptors and its defective expression is associated with synaptic dysfunction and cognitive impairment. In T lymphocytes, SNX27 was found localized at recycling endosomal compartments that polarized to the IS, suggesting a function in polarized traffic to this structure. Proteomic analysis of PDZ-SNX27 interactors during IS formation identify proteins with known functions in cytoskeletal reorganization and lipid regulation, such as diacylglycerol (DAG) kinase (DGK) ζ, as well as components of the retromer and WASH complex. In this study, we investigated the consequences of SNX27 deficiency in cytoskeletal reorganization during IS formation. Our analyses demonstrate that SNX27 controls the polarization towards the cell-cell interface of the PDZ-interacting cargoes DGKζ and the retromer subunit vacuolar protein sorting protein 26, among others. SNX27 silencing abolishes the formation of a DAG gradient at the IS and prevents re-localization of the dynactin complex component dynactin-1/p150Glued, two events that correlate with impaired microtubule organizing center translocation (MTOC). SNX27 silenced cells show marked alteration in cytoskeleton organization including a failure in the organization of the microtubule network and defects in actin clearance at the IS. Reduced SNX27 expression was also found to hinder the arrangement of signaling microclusters at the IS, as well as the polarization of the secretory machinery towards the antigen presenting cells. Our results broaden the knowledge of SNX27 function in T lymphocytes by showing a function in modulating IS organization through regulated trafficking of cargoes.
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Affiliation(s)
- Natalia González-Mancha
- Department of Immunology and Oncology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
| | - Cristina Rodríguez-Rodríguez
- Department of Immunology and Oncology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
| | - Andrés Alcover
- Institut Pasteur, Université de Paris, Unité Biologie Cellulaire des Lymphocytes, INSERM U1224, Ligue Nationale Contre le Cancer, Équipe Labellisée Ligue-2018, Paris, France
| | - Isabel Merida
- Department of Immunology and Oncology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
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6
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Orłowska M, Muszewska A. In Silico Predictions of Ecological Plasticity Mediated by Protein Family Expansions in Early-Diverging Fungi. J Fungi (Basel) 2022; 8:67. [PMID: 35050007 PMCID: PMC8778642 DOI: 10.3390/jof8010067] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 01/06/2022] [Accepted: 01/07/2022] [Indexed: 11/16/2022] Open
Abstract
Early-diverging fungi (EDF) are ubiquitous and versatile. Their diversity is reflected in their genome sizes and complexity. For instance, multiple protein families have been reported to expand or disappear either in particular genomes or even whole lineages. The most commonly mentioned are CAZymes (carbohydrate-active enzymes), peptidases and transporters that serve multiple biological roles connected to, e.g., metabolism and nutrients intake. In order to study the link between ecology and its genomic underpinnings in a more comprehensive manner, we carried out a systematic in silico survey of protein family expansions and losses among EDF with diverse lifestyles. We found that 86 protein families are represented differently according to EDF ecological features (assessed by median count differences). Among these there are 19 families of proteases, 43 CAZymes and 24 transporters. Some of these protein families have been recognized before as serine and metallopeptidases, cellulases and other nutrition-related enzymes. Other clearly pronounced differences refer to cell wall remodelling and glycosylation. We hypothesize that these protein families altogether define the preliminary fungal adaptasome. However, our findings need experimental validation. Many of the protein families have never been characterized in fungi and are discussed in the light of fungal ecology for the first time.
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Affiliation(s)
- Małgorzata Orłowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland
| | - Anna Muszewska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland
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7
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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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8
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Chandra M, Kendall AK, Jackson LP. Toward Understanding the Molecular Role of SNX27/Retromer in Human Health and Disease. Front Cell Dev Biol 2021; 9:642378. [PMID: 33937239 PMCID: PMC8083963 DOI: 10.3389/fcell.2021.642378] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/22/2021] [Indexed: 11/30/2022] Open
Abstract
Aberrations in membrane trafficking pathways have profound effects in cellular dynamics of cellular sorting processes and can drive severe physiological outcomes. Sorting nexin 27 (SNX27) is a metazoan-specific sorting nexin protein from the PX-FERM domain family and is required for endosomal recycling of many important transmembrane receptors. Multiple studies have shown SNX27-mediated recycling requires association with retromer, one of the best-known regulators of endosomal trafficking. SNX27/retromer downregulation is strongly linked to Down's Syndrome (DS) via glutamate receptor dysfunction and to Alzheimer's Disease (AD) through increased intracellular production of amyloid peptides from amyloid precursor protein (APP) breakdown. SNX27 is further linked to addiction via its role in potassium channel trafficking, and its over-expression is linked to tumorigenesis, cancer progression, and metastasis. Thus, the correct sorting of multiple receptors by SNX27/retromer is vital for normal cellular function to prevent human diseases. The role of SNX27 in regulating cargo recycling from endosomes to the cell surface is firmly established, but how SNX27 assembles with retromer to generate tubulovesicular carriers remains elusive. Whether SNX27/retromer may be a putative therapeutic target to prevent neurodegenerative disease is now an emerging area of study. This review will provide an update on our molecular understanding of endosomal trafficking events mediated by the SNX27/retromer complex on endosomes.
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Affiliation(s)
- Mintu Chandra
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
- Center for Structural Biology, Vanderbilt University, Nashville, TN, United States
| | - Amy K. Kendall
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
- Center for Structural Biology, Vanderbilt University, Nashville, TN, United States
| | - Lauren P. Jackson
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
- Center for Structural Biology, Vanderbilt University, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
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9
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Potential role of diacylglycerol kinases in immune-mediated diseases. Clin Sci (Lond) 2021; 134:1637-1658. [PMID: 32608491 DOI: 10.1042/cs20200389] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/08/2020] [Accepted: 06/22/2020] [Indexed: 02/07/2023]
Abstract
The mechanism promoting exacerbated immune responses in allergy and autoimmunity as well as those blunting the immune control of cancer cells are of primary interest in medicine. Diacylglycerol kinases (DGKs) are key modulators of signal transduction, which blunt diacylglycerol (DAG) signals and produce phosphatidic acid (PA). By modulating lipid second messengers, DGK modulate the activity of downstream signaling proteins, vesicle trafficking and membrane shape. The biological role of the DGK α and ζ isoforms in immune cells differentiation and effector function was subjected to in deep investigations. DGK α and ζ resulted in negatively regulating synergistic way basal and receptor induced DAG signals in T cells as well as leukocytes. In this way, they contributed to keep under control the immune response but also downmodulate immune response against tumors. Alteration in DGKα activity is also implicated in the pathogenesis of genetic perturbations of the immune function such as the X-linked lymphoproliferative disease 1 and localized juvenile periodontitis. These findings suggested a participation of DGK to the pathogenetic mechanisms underlying several immune-mediated diseases and prompted several researches aiming to target DGK with pharmacologic and molecular strategies. Those findings are discussed inhere together with experimental applications in tumors as well as in other immune-mediated diseases such as asthma.
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10
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Bao Z, Zhou S, Zhou H. Sorting Nexin 27 as a potential target in G protein‑coupled receptor recycling for cancer therapy (Review). Oncol Rep 2020; 44:1779-1786. [PMID: 33000258 PMCID: PMC7551096 DOI: 10.3892/or.2020.7766] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 08/10/2020] [Indexed: 12/12/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are the largest family of membrane receptors and activate several downstream signaling pathways involved in numerous physiological cellular processes. GPCRs are usually internalized and desensitized by intracellular signals. Numerous studies have shown that several GPCRs interact with sorting nexin 27 (SNX27), a cargo selector of the retromer complex, and are recycled from endosomes to the plasma membrane. Recycled GPCRs usually contain specific C-terminal postsynaptic density protein 95/Discs large protein/Zonula occludens 1 (PDZ) binding motifs, which are specifically recognized by SNX27, and return to the cell surface as functionally naïve receptors. Aberrant endosome-to-membrane recycling of GPCRs mediated by SNX27 may serve a critical role in cancer growth and development. Therefore, SNX27 may be a novel target for cancer therapies.
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Affiliation(s)
- Zixu Bao
- Department of Biochemistry and Molecular Biology, Anhui Medical University, Hefei, Anhui 230032, P.R. China
| | - Shijun Zhou
- Department of Infectious Disease, The Second Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230601, P.R. China
| | - Haisheng Zhou
- Department of Biochemistry and Molecular Biology, Anhui Medical University, Hefei, Anhui 230032, P.R. China
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11
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Sharma P, Parveen S, Shah LV, Mukherjee M, Kalaidzidis Y, Kozielski AJ, Rosato R, Chang JC, Datta S. SNX27-retromer assembly recycles MT1-MMP to invadopodia and promotes breast cancer metastasis. J Cell Biol 2020; 219:132732. [PMID: 31820782 PMCID: PMC7039210 DOI: 10.1083/jcb.201812098] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 07/26/2019] [Accepted: 10/21/2019] [Indexed: 12/25/2022] Open
Abstract
Recycling of MT-MMPs to actin-rich membrane-protrusive structures promotes breast cancer invasion. This study shows that SNX27–retromer, an endosomal sorting and recycling machinery, interacts with MT1-MMP and regulates its transport to the cell surface, thus promoting matrix invasive activity of the breast cancer cells. A variety of metastatic cancer cells use actin-rich membrane protrusions, known as invadopodia, for efficient ECM degradation, which involves trafficking of proteases from intracellular compartments to these structures. Here, we demonstrate that in the metastatic breast cancer cell line MDA-MB-231, retromer regulates the matrix invasion activity by recycling matrix metalloprotease, MT1-MMP. We further found that MT2-MMP, another abundantly expressed metalloprotease, is also invadopodia associated. MT1- and MT2-MMP showed a high degree of colocalization but were located on the distinct endosomal domains. Retromer and its associated sorting nexin, SNX27, phenocopied each other in matrix degradation via selectively recycling MT1-MMP but not MT2-MMP. ITC-based studies revealed that both SNX27 and retromer could directly interact with MT1-MMP. Analysis from a publicly available database showed SNX27 to be overexpressed or frequently altered in the patients having invasive breast cancer. In xenograft-based studies, SNX27-depleted cell lines showed prolonged survival of SCID mice, suggesting a possible implication for overexpression of the sorting nexin in tumor samples.
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Affiliation(s)
- Priyanka Sharma
- Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Bhopal, India
| | - Sameena Parveen
- Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Bhopal, India
| | - Lekha V Shah
- Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Bhopal, India
| | - Madhumita Mukherjee
- Department of Chemistry, Indian Institute of Science Education and Research, Bhopal, Bhopal, India
| | - Yannis Kalaidzidis
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Faculty of Bioengineering and Bioinformatics, Moscow State University, Moscow, Russia
| | | | | | | | - Sunando Datta
- Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Bhopal, India
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12
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González-Mancha N, Mérida I. Interplay Between SNX27 and DAG Metabolism in the Control of Trafficking and Signaling at the IS. Int J Mol Sci 2020; 21:ijms21124254. [PMID: 32549284 PMCID: PMC7352468 DOI: 10.3390/ijms21124254] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/09/2020] [Accepted: 06/10/2020] [Indexed: 12/13/2022] Open
Abstract
Recognition of antigens displayed on the surface of an antigen-presenting cell (APC) by T-cell receptors (TCR) of a T lymphocyte leads to the formation of a specialized contact between both cells named the immune synapse (IS). This highly organized structure ensures cell–cell communication and sustained T-cell activation. An essential lipid regulating T-cell activation is diacylglycerol (DAG), which accumulates at the cell–cell interface and mediates recruitment and activation of proteins involved in signaling and polarization. Formation of the IS requires rearrangement of the cytoskeleton, translocation of the microtubule-organizing center (MTOC) and vesicular compartments, and reorganization of signaling and adhesion molecules within the cell–cell junction. Among the multiple players involved in this polarized intracellular trafficking, we find sorting nexin 27 (SNX27). This protein translocates to the T cell–APC interface upon TCR activation, and it is suggested to facilitate the transport of cargoes toward this structure. Furthermore, its interaction with diacylglycerol kinase ζ (DGKζ), a negative regulator of DAG, sustains the precise modulation of this lipid and, thus, facilitates IS organization and signaling. Here, we review the role of SNX27, DAG metabolism, and their interplay in the control of T-cell activation and establishment of the IS.
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13
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Bannert K, Berlin P, Reiner J, Lemcke H, David R, Engelmann R, Lamprecht G. SNX27 regulates DRA activity and mediates its direct recycling by PDZ-interaction in early endosomes at the apical pole of Caco2 cells. Am J Physiol Gastrointest Liver Physiol 2020; 318:G854-G869. [PMID: 32116023 DOI: 10.1152/ajpgi.00374.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
DRA (downregulated in adenoma, SLC26A3) and NHE3 (Na+/H+ exchanger 3, SLC9A3) together mediate intestinal electroneutral NaCl absorption. Both transporters contain PDZ (postsynaptic density 95, disc large, zonula occludens 1) binding motifs and interact with PDZ adaptor proteins regulating their activity and recycling. SNX27 (sorting nexin 27) contains a PDZ domain and is involved in the recycling of cargo proteins including NHE3. The interaction of SNX27 with DRA and its potential role for the activity and recycling of DRA have been evaluated in this study. SNX27 specifically interacts with DRA via its PDZ domain. The knockdown (KD) of SNX27 reduced DRA activity by 50% but was not accompanied by a decrease of DRA surface expression. This indicates that DRA is trafficked to specific functional domains in the plasma membrane in which DRA is particularly active. Consistently, the disruption of lipid raft integrity by methyl-β-cyclodextrin has an inhibitory effect on DRA activity that was strongly reduced after SNX27 KD. In differentiated intestinal Caco2 cells, superresolution microscopy and a novel quantitative axial approach revealed that DRA and SNX27 colocalize in rab5-positive early endosomes at the apical pole. SNX27 regulates the activity of DRA in the apical plasma membrane through binding with its PDZ domain. This interaction occurs in rab5-positive early endosomes at the apical pole of differentiated intestinal Caco2 cells. SNX27 is involved in the direct recycling of DRA to the plasma membrane where it is inserted into lipid rafts facilitating increased activity.NEW & NOTEWORTHY SNX27 has a PDZ domain and is involved in the regulation and recycling of transmembrane proteins. The role of SNX27 on the activity and recycling of the intestinal Cl-/HCO3- exchanger DRA has not yet been studied. This study shows that SNX27 directly interacts with DRA in early endosomes at the apical pole of intestinal Caco2 cells and mediates its direct recycling to facilitate high activity in lipid rafts in the apical plasma membrane.
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Affiliation(s)
- Karen Bannert
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
| | - Peggy Berlin
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
| | - Johannes Reiner
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
| | - Heiko Lemcke
- Department of Cardiac Surgery, Rostock University Medical Center, Rostock, Germany.,Department Life, Light and Matter, University of Rostock, Rostock, Germany
| | - Robert David
- Department of Cardiac Surgery, Rostock University Medical Center, Rostock, Germany.,Department Life, Light and Matter, University of Rostock, Rostock, Germany
| | - Robby Engelmann
- Institute of Immunology, Rostock University Medical Center, Rostock, Germany
| | - Georg Lamprecht
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
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14
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Monnot GC, Martinez-Usatorre A, Lanitis E, Lopes SF, Cheng WC, Ho PC, Irving M, Coukos G, Donda A, Romero P. miR-155 Overexpression in OT-1 CD8 + T Cells Improves Anti-Tumor Activity against Low-Affinity Tumor Antigen. Mol Ther Oncolytics 2020; 16:111-123. [PMID: 32021906 PMCID: PMC6994712 DOI: 10.1016/j.omto.2019.12.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 12/16/2019] [Indexed: 12/27/2022] Open
Abstract
Therapy by adoptive transfer of ex vivo-expanded tumor-infiltrating or genetically modified T cells may lead to impressive clinical responses. However, there is a need to improve in vivo persistence and functionality of the transferred T cells, in particular, to face the highly immunosuppressive environment of solid tumors. Here, we investigate the potential of miR-155, a microRNA known to play an important role in CD8+ T cell fitness. We show that forced expression of miR-155 in tumor antigen-specific T cells improves the tumor control of B16 tumors expressing a low-affinity antigen ligand. Importantly, miR-155-transduced T cells exhibit increased proliferation and effector functions associated with a higher glycolytic activity independent of exogenous glucose. Altogether, these data suggest that miR-155 may optimize the antitumor activity of adoptively transferred low-affinity tumor-infiltrating lymphocytes (TILs), in particular, by rendering them more resistant to the glucose-deprived environment of solid tumors. Thus, transgenic expression of miR-155 may enable therapeutic targeting of self-antigen-specific T cells in addition to neoantigen-specific ones.
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Affiliation(s)
- Gwennaëlle C. Monnot
- Department of Fundamental Oncology and Ludwig Cancer Center, Faculty of Biology and Medicine, University of Lausanne, 1066 Epalinges, Switzerland
| | - Amaia Martinez-Usatorre
- Department of Fundamental Oncology and Ludwig Cancer Center, Faculty of Biology and Medicine, University of Lausanne, 1066 Epalinges, Switzerland
| | - Evripidis Lanitis
- Ludwig Institute for Cancer Research, Lausanne Branch at the University of Lausanne, 1066 Epalinges, Switzerland
| | - Silvia Ferreira Lopes
- Department of Fundamental Oncology and Ludwig Cancer Center, Faculty of Biology and Medicine, University of Lausanne, 1066 Epalinges, Switzerland
| | - Wan-Chen Cheng
- Department of Fundamental Oncology and Ludwig Cancer Center, Faculty of Biology and Medicine, University of Lausanne, 1066 Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch at the University of Lausanne, 1066 Epalinges, Switzerland
| | - Ping-Chih Ho
- Department of Fundamental Oncology and Ludwig Cancer Center, Faculty of Biology and Medicine, University of Lausanne, 1066 Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch at the University of Lausanne, 1066 Epalinges, Switzerland
| | - Melita Irving
- Department of Fundamental Oncology and Ludwig Cancer Center, Faculty of Biology and Medicine, University of Lausanne, 1066 Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch at the University of Lausanne, 1066 Epalinges, Switzerland
| | - George Coukos
- Department of Fundamental Oncology and Ludwig Cancer Center, Faculty of Biology and Medicine, University of Lausanne, 1066 Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch at the University of Lausanne, 1066 Epalinges, Switzerland
| | - Alena Donda
- Department of Fundamental Oncology and Ludwig Cancer Center, Faculty of Biology and Medicine, University of Lausanne, 1066 Epalinges, Switzerland
| | - Pedro Romero
- Department of Fundamental Oncology and Ludwig Cancer Center, Faculty of Biology and Medicine, University of Lausanne, 1066 Epalinges, Switzerland
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15
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Barber CN, Raben DM. Roles of DGKs in neurons: Postsynaptic functions? Adv Biol Regul 2019; 75:100688. [PMID: 31836314 DOI: 10.1016/j.jbior.2019.100688] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Revised: 11/08/2019] [Accepted: 11/18/2019] [Indexed: 01/12/2023]
Abstract
Diacylglycerol kinases (DGKs) contribute to an important part of intracellular signaling because, in addition to reducing diacylglycerol levels, they generate phosphatidic acid (PtdOH) Recent research has led to the discovery of ten mammalian DGK isoforms, all of which are found in the mammalian brain. Many of these isoforms have studied functions within the brain, while others lack such understanding in regards to neuronal roles, regulation, and structural dynamics. However, while previously a neuronal function for DGKθ was unknown, it was recently found that DGKθ is required for the regulation of synaptic vesicle endocytosis and work is currently being conducted to elucidate the mechanism behind this regulation. Here we will review some of the roles of all mammalian DGKs and hypothesize additional roles. We will address the topic of redundancy among the ten DGK isoforms and discuss the possibility that DGKθ, among other DGKs, may have unstudied postsynaptic functions. We also hypothesize that in addition to DGKθ's presynaptic endocytic role, DGKθ might also regulate the endocytosis of AMPA receptors and other postsynaptic membrane proteins.
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Affiliation(s)
- Casey N Barber
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD, 21205, USA
| | - Daniel M Raben
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD, 21205, USA.
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16
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Abstract
OTULIN (OTU Deubiquitinase With Linear Linkage Specificity) specifically hydrolyzes methionine1 (Met1)-linked ubiquitin chains conjugated by LUBAC (linear ubiquitin chain assembly complex). Here we report on the mass spectrometric identification of the OTULIN interactor SNX27 (sorting nexin 27), an adaptor of the endosomal retromer complex responsible for protein recycling to the cell surface. The C-terminal PDZ-binding motif (PDZbm) in OTULIN associates with the cargo-binding site in the PDZ domain of SNX27. By solving the structure of the OTU domain in complex with the PDZ domain, we demonstrate that a second interface contributes to the selective, high affinity interaction of OTULIN and SNX27. SNX27 does not affect OTULIN catalytic activity, OTULIN-LUBAC binding or Met1-linked ubiquitin chain homeostasis. However, via association, OTULIN antagonizes SNX27-dependent cargo loading, binding of SNX27 to the VPS26A-retromer subunit and endosome-to-plasma membrane trafficking. Thus, we define an additional, non-catalytic function of OTULIN in the regulation of SNX27-retromer assembly and recycling to the cell surface. OTULIN is a linear ubiquitin hydrolase that regulates ubiquitin homeostasis. Here the authors identify the adaptor of the endosomal retromer complex sorting nexin 27 (SNX27) as a binding partner of OTULIN and determine the structure of the OTULIN-SNX27 complex, which reveals a secondary interface through which OTULIN non-catalytically antagonizes SNX27 retromer assembly and cargo loading.
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17
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Gutiérrez-González LH, Santos-Mendoza T. Viral targeting of PDZ polarity proteins in the immune system as a potential evasion mechanism. FASEB J 2019; 33:10607-10617. [PMID: 31336050 DOI: 10.1096/fj.201900518r] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PDZ proteins are highly conserved through evolution; the principal function of this large family of proteins is to assemble protein complexes that are involved in many cellular processes, such as cell-cell junctions, cell polarity, recycling, or trafficking. Many PDZ proteins that have been identified as targets of viral pathogens by promoting viral replication and spread are also involved in epithelial cell polarity. Here, we briefly review the PDZ polarity proteins in cells of the immune system to subsequently focus on our hypothesis that the viral PDZ-dependent targeting of PDZ polarity proteins in these cells may alter the cellular fitness of the host to favor that of the virus; we further hypothesize that this modification of the cellular fitness landscape occurs as a common and widespread mechanism for immune evasion by viruses and possibly other pathogens.-Gutiérrez-González, L. H., Santos-Mendoza, T. Viral targeting of PDZ polarity proteins in the immune system as a potential evasion mechanism.
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Affiliation(s)
- Luis H Gutiérrez-González
- Department of Virology and Mycology, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Teresa Santos-Mendoza
- Laboratory of Autoimmunity, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
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18
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Diacylglycerol kinase control of protein kinase C. Biochem J 2019; 476:1205-1219. [DOI: 10.1042/bcj20180620] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 03/29/2019] [Accepted: 04/01/2019] [Indexed: 12/27/2022]
Abstract
Abstract
The diacylglycerol kinases (DGK) are lipid kinases that transform diacylglycerol (DAG) into phosphatidic acid (PA) in a reaction that terminates DAG-based signals. DGK provide negative regulation to conventional and novel protein kinase C (PKC) enzymes, limiting local DAG availability in a tissue- and subcellular-restricted manner. Defects in the expression/activity of certain DGK isoforms contribute substantially to cognitive impairment and mental disorders. Abnormal DGK overexpression in tumors facilitates invasion and resistance to chemotherapy preventing tumor immune destruction by tumor-infiltrating lymphocytes. Effective translation of these findings into therapeutic approaches demands a better knowledge of the physical and functional interactions between the DGK and PKC families. DGKζ is abundantly expressed in the nervous and immune system, where physically and functionally interacts with PKCα. The latest discoveries suggest that PDZ-mediated interaction facilitates spatial restriction of PKCα by DGKζ at the cell–cell contact sites in a mechanism where the two enzymes regulate each other. In T lymphocytes, DGKζ interaction with Sorting Nexin 27 (SNX27) guarantees the basal control of PKCα activation. SNX27 is a trafficking component required for normal brain function whose deficit has been linked to Alzheimer's disease (AD) pathogenesis. The enhanced PKCα activation as the result of SNX27 silencing in T lymphocytes aligns with the recent correlation found between gain-of-function PKCα mutations and AD and suggests that disruption of the mechanisms that provides a correct spatial organization of DGKζ and PKCα may lie at the basis of immune and neuronal synapse impairment.
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19
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Naslavsky N, Caplan S. The enigmatic endosome - sorting the ins and outs of endocytic trafficking. J Cell Sci 2018; 131:131/13/jcs216499. [PMID: 29980602 DOI: 10.1242/jcs.216499] [Citation(s) in RCA: 195] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The early endosome (EE), also known as the sorting endosome (SE) is a crucial station for the sorting of cargoes, such as receptors and lipids, through the endocytic pathways. The term endosome relates to the receptacle-like nature of this organelle, to which endocytosed cargoes are funneled upon internalization from the plasma membrane. Having been delivered by the fusion of internalized vesicles with the EE or SE, cargo molecules are then sorted to a variety of endocytic pathways, including the endo-lysosomal pathway for degradation, direct or rapid recycling to the plasma membrane, and to a slower recycling pathway that involves a specialized form of endosome known as a recycling endosome (RE), often localized to the perinuclear endocytic recycling compartment (ERC). It is striking that 'the endosome', which plays such essential cellular roles, has managed to avoid a precise description, and its characteristics remain ambiguous and heterogeneous. Moreover, despite the rapid advances in scientific methodologies, including breakthroughs in light microscopy, overall, the endosome remains poorly defined. This Review will attempt to collate key characteristics of the different types of endosomes and provide a platform for discussion of this unique and fascinating collection of organelles. Moreover, under-developed, poorly understood and important open questions will be discussed.
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Affiliation(s)
- Naava Naslavsky
- The Department of Biochemistry and Molecular Biology, The University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Steve Caplan
- The Department of Biochemistry and Molecular Biology, The University of Nebraska Medical Center, Omaha, NE 68198, USA .,The Fred and Pamela Buffett Cancer Center, The University of Nebraska Medical Center, Omaha, NE 68198, USA
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20
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Gupta MK, Mohan ML, Naga Prasad SV. G Protein-Coupled Receptor Resensitization Paradigms. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 339:63-91. [PMID: 29776605 DOI: 10.1016/bs.ircmb.2018.03.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cellular responses to extracellular milieu/environment are driven by cell surface receptors that transmit the signal into the cells resulting in a synchronized and measured response. The ability to provide such exquisite responses to changes in external environment is mediated by the tight and yet, deliberate regulation of cell surface receptor function. In this regard, the seven transmembrane G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors that regulate responses like cardiac contractility, vision, and olfaction including platelet activation. GPCRs regulate these plethora of events through GPCR-activation, -desensitization, and -resensitization. External stimuli (ligands or agonists) activate GPCR initiating downstream signals. The activated GPCR undergoes inactivation or desensitization by phosphorylation and binding of β-arrestin resulting in diminution of downstream signals. The desensitized GPCRs are internalized into endosomes, wherein they undergo dephosphorylation or resensitization by protein phosphatase to be recycled back to the cell membrane as naïve GPCR ready for the next wave of stimuli. Despite the knowledge that activation, desensitization, and resensitization shoulder an equal role in maintaining GPCR function, major advances have been made in understanding activation and desensitization compared to resensitization. However, increasing evidence shows that resensitization is exquisitely regulated process, thereby contributing to the dynamic regulation of GPCR function. In recognition of these observations, in this chapter we discuss the key advances on the mechanistic underpinning that drive and regulate GPCR function with a focus on resensitization.
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Affiliation(s)
- Manveen K Gupta
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Maradumane L Mohan
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Sathyamangla V Naga Prasad
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States.
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21
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SNX27 links DGKζ to the control of transcriptional and metabolic programs in T lymphocytes. Sci Rep 2017; 7:16361. [PMID: 29180720 PMCID: PMC5703713 DOI: 10.1038/s41598-017-16370-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 11/10/2017] [Indexed: 01/10/2023] Open
Abstract
Sorting nexin 27 (SNX27) recycles PSD-95, Dlg1, ZO-1 (PDZ) domain-interacting membrane proteins and is essential to sustain adequate brain functions. Here we define a fundamental SNX27 function in T lymphocytes controlling antigen-induced transcriptional activation and metabolic reprogramming. SNX27 limits the activation of diacylglycerol (DAG)-based signals through its high affinity PDZ-interacting cargo DAG kinase ζ (DGKζ). SNX27 silencing in human T cells enhanced T cell receptor (TCR)-stimulated activator protein 1 (AP-1)- and nuclear factor κB (NF-κB)-mediated transcription. Transcription did not increase upon DGKζ silencing, suggesting that DGKζ function is dependent on SNX27. The enhanced transcriptional activation in SNX27-silenced cells contrasted with defective activation of the mammalian target of rapamycin (mTOR) pathway. The analysis of Snx27−/− mice supported a role for SNX27 in the control of T cell growth. This study broadens our understanding of SNX27 as an integrator of lipid-based signals with the control of transcription and metabolic pathways.
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22
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Bahouth SW, Nooh MM. Barcoding of GPCR trafficking and signaling through the various trafficking roadmaps by compartmentalized signaling networks. Cell Signal 2017; 36:42-55. [PMID: 28449947 PMCID: PMC5512170 DOI: 10.1016/j.cellsig.2017.04.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 04/21/2017] [Accepted: 04/22/2017] [Indexed: 01/08/2023]
Abstract
Proper signaling by G protein coupled receptors (GPCR) is dependent on the specific repertoire of transducing, enzymatic and regulatory kinases and phosphatases that shape its signaling output. Activation and signaling of the GPCR through its cognate G protein is impacted by G protein-coupled receptor kinase (GRK)-imprinted "barcodes" that recruit β-arrestins to regulate subsequent desensitization, biased signaling and endocytosis of the GPCR. The outcome of agonist-internalized GPCR in endosomes is also regulated by sequence motifs or "barcodes" within the GPCR that mediate its recycling to the plasma membrane or retention and eventual degradation as well as its subsequent signaling in endosomes. Given the vast number of diverse sequences in GPCR, several trafficking mechanisms for endosomal GPCR have been described. The majority of recycling GPCR, are sorted out of endosomes in a "sequence-dependent pathway" anchored around a type-1 PDZ-binding module found in their C-tails. For a subset of these GPCR, a second "barcode" imprinted onto specific GPCR serine/threonine residues by compartmentalized kinase networks was required for their efficient recycling through the "sequence-dependent pathway". Mutating the serine/threonine residues involved, produced dramatic effects on GPCR trafficking, indicating that they played a major role in setting the trafficking itinerary of these GPCR. While endosomal SNX27, retromer/WASH complexes and actin were required for efficient sorting and budding of all these GPCR, additional proteins were required for GPCR sorting via the second "barcode". Here we will review recent developments in GPCR trafficking in general and the human β1-adrenergic receptor in particular across the various trafficking roadmaps. In addition, we will discuss the role of GPCR trafficking in regulating endosomal GPCR signaling, which promote biochemical and physiological effects that are distinct from those generated by the GPCR signal transduction pathway in membranes.
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Affiliation(s)
- Suleiman W Bahouth
- Department of Pharmacology, The University of Tennessee Health Sciences Center, 71 S. Manassas, Memphis, TN 38103, USA.
| | - Mohammed M Nooh
- Department of Biochemistry, Faculty of Pharmacy Cairo University, Kasr El-Aini St., Cairo 11562, Egypt
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23
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Tello-Lafoz M, Martínez-Martínez G, Rodríguez-Rodríguez C, Albar JP, Huse M, Gharbi S, Merida I. Sorting nexin 27 interactome in T-lymphocytes identifies zona occludens-2 dynamic redistribution at the immune synapse. Traffic 2017; 18:491-504. [PMID: 28477369 DOI: 10.1111/tra.12492] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 04/28/2017] [Accepted: 05/03/2017] [Indexed: 12/27/2022]
Abstract
T Lymphocyte recognition of antigens leads to the formation of a highly organized structure termed immune synapse (IS) by analogy with the neuronals synapse. Sorting nexin 27 (SNX27) controls the endosomal traffic of PSD95, Dlg1, ZO-1 (PDZ) domain-interacting proteins, and its alteration is associated with impaired synaptic function and neurological diseases. In T-lymphocytes, SNX27-positive vesicles polarize to the IS, the identity of SNX27 interactors in these conditions nonetheless remains unknown. Here we used proteomics to analyze the SNX27 interactome purified from IS-forming T cells, and confirmed the conserved nature of the SNX27/WASH/retromer association in hematopoietic cells. Furthermore, our comparative interactome analysis of SNX27 wild-type and a mutant-deficient for PDZ cargo recognition identified the epithelial cell-cell junction protein zona occludens-2 (ZO-2) as an IS component. Biochemistry and microscopy approaches in T cells confirmed SNX27/ZO-2 PDZ-dependent interaction, and demonstrated its role controlling the dynamic localization of ZO-2 at the IS. This study broadens our knowledge of SNX27 function in T lymphocytes, and suggests that pathways that delimit polarized structures in nervous and epithelial systems also participate in IS regulation.
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Affiliation(s)
- María Tello-Lafoz
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | - Gonzalo Martínez-Martínez
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain.,Proteomics Laboratory, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | | | - Juan Pablo Albar
- Proteomics Laboratory, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | - Morgan Huse
- Immunology Program, Memorial Sloan-Kettering Cancer Center, New York City, New York
| | - Severine Gharbi
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain.,Proteomics Laboratory, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | - Isabel Merida
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
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24
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Andrada E, Almena M, de Guinoa JS, Merino-Cortes SV, Liebana R, Arcos R, Carrasco S, Carrasco YR, Merida I. Diacylglycerol kinase limits the polarized recruitment of diacylglycerol-enriched organelles to the immune synapse in T cells. Sci Signal 2016; 9:ra127. [DOI: 10.1126/scisignal.aaf7714] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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25
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A molecular code for endosomal recycling of phosphorylated cargos by the SNX27-retromer complex. Nat Struct Mol Biol 2016; 23:921-932. [PMID: 27595347 DOI: 10.1038/nsmb.3290] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 08/11/2016] [Indexed: 12/11/2022]
Abstract
Recycling of internalized receptors from endosomal compartments is essential for the receptors' cell-surface homeostasis. Sorting nexin 27 (SNX27) cooperates with the retromer complex in the recycling of proteins containing type I PSD95-Dlg-ZO1 (PDZ)-binding motifs. Here we define specific acidic amino acid sequences upstream of the PDZ-binding motif required for high-affinity engagement of the human SNX27 PDZ domain. However, a subset of SNX27 ligands, such as the β2 adrenergic receptor and N-methyl-D-aspartate (NMDA) receptor, lack these sequence determinants. Instead, we identified conserved sites of phosphorylation that substitute for acidic residues and dramatically enhance SNX27 interactions. This newly identified mechanism suggests a likely regulatory switch for PDZ interaction and protein transport by the SNX27-retromer complex. Defining this SNX27 binding code allowed us to classify more than 400 potential SNX27 ligands with broad functional implications in signal transduction, neuronal plasticity and metabolite transport.
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26
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Ghai R, Tello-Lafoz M, Norwood SJ, Yang Z, Clairfeuille T, Teasdale RD, Mérida I, Collins BM. Phosphoinositide binding by the SNX27 FERM domain regulates its localization at the immune synapse of activated T-cells. J Cell Sci 2016; 128:553-65. [PMID: 25472716 DOI: 10.1242/jcs.158204] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Sorting nexin 27 (SNX27) controls the endosomal-to-cell-surface recycling of diverse transmembrane protein cargos. Crucial to this function is the recruitment of SNX27 to endosomes which is mediated by the binding of phosphatidylinositol-3-phosphate (PtdIns3P) by its phox homology (PX) domain. In T-cells, SNX27 localizes to the immunological synapse in an activation-dependent manner, but the molecular mechanisms underlying SNX27 translocation remain to be clarified. Here, we examined the phosphoinositide-lipid-binding capabilities of full-length SNX27, and discovered a new PtdInsP-binding site within the C-terminal 4.1, ezrin, radixin, moesin (FERM) domain. This binding site showed a clear preference for bi- and tri-phosphorylated phophoinositides, and the interaction was confirmed through biophysical, mutagenesis and modeling approaches. At the immunological synapse of activated T-cells, cell signaling regulates phosphoinositide dynamics, and we find that perturbing phosphoinositide binding by the SNX27 FERM domain alters the SNX27 distribution in both endosomal recycling compartments and PtdIns(3,4,5)P3-enriched domains of the plasma membrane during synapse formation. Our results suggest that SNX27 undergoes dynamic partitioning between different membrane domains during immunological synapse assembly, and underscore the contribution of unique lipid interactions for SNX27 orchestration of cargo trafficking.
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27
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Loss of Diacylglycerol Kinase-Ζ Inhibits Cell Proliferation and Survival in Human Gliomas. Mol Neurobiol 2015; 53:5425-35. [DOI: 10.1007/s12035-015-9419-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 09/02/2015] [Indexed: 12/25/2022]
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28
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Torres-Ayuso P, Tello-Lafoz M, Mérida I, Ávila-Flores A. Diacylglycerol kinase-ζ regulates mTORC1 and lipogenic metabolism in cancer cells through SREBP-1. Oncogenesis 2015; 4:e164. [PMID: 26302180 PMCID: PMC4632073 DOI: 10.1038/oncsis.2015.22] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 06/26/2015] [Accepted: 07/07/2015] [Indexed: 01/03/2023] Open
Abstract
Diacylglycerol kinases (DGKs) transform diacylglycerol (DAG) into phosphatidic acid (PA), balancing the levels of these key metabolic and signaling lipids. We previously showed that PA derived from the DGKζ isoform promotes mammalian target of rapamycin complex 1 (mTORC1) activation. This function might be crucial for the growth and survival of cancer cells, especially for those resistant to the allosteric mTOR inhibitor rapamycin. How this positive function of DGKζ coordinates with DAG metabolism and signaling is unknown. In this study, we used a rapamycin-resistant colon cancer cell line as a model to address the role of DGKζ in tumor cells. We found that DGKζ predominated over other PA sources such as DGKα or phospholipase D to activate mTORC1, and that its activity was a component of the rapamycin-induced feedback loops. We show that the DGKζ DAG-consuming function is central to cell homeostasis, as DAG negatively regulates levels of the lipogenic transcription factor SREBP-1. Our findings suggest a model in which simultaneous regulation of DAG and PA levels by DGKζ is integrated with mTOR function to maintain tumor cell homeostasis; we provide new evidence of the crosstalk between mTOR and lipid metabolism that will be advantageous in the design of drug therapies.
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Affiliation(s)
- P Torres-Ayuso
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - M Tello-Lafoz
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - I Mérida
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - A Ávila-Flores
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
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Xie S, Naslavsky N, Caplan S. Diacylglycerol kinases in membrane trafficking. CELLULAR LOGISTICS 2015; 5:e1078431. [PMID: 27057419 DOI: 10.1080/21592799.2015.1078431] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 07/22/2015] [Accepted: 07/24/2015] [Indexed: 10/23/2022]
Abstract
Diacylglycerol kinases (DGKs) belong to a family of cytosolic kinases that regulate the phosphorylation of diacylglycerol (DAG), converting it into phosphatidic acid (PA). There are 10 known mammalian DGK isoforms, each with a different tissue distribution and substrate specificity. These differences allow regulation of cellular responses by fine-tuning the delicate balance of cellular DAG and PA. DGK isoforms are best characterized as mediators of signal transduction and immune function. However, since recent studies reveal that DAG and PA are also involved in the regulation of endocytic trafficking, it is therefore anticipated that DGKs also plays an important role in membrane trafficking. In this review, we summarize the literature discussing the role of DGK isoforms at different stages of endocytic trafficking, including endocytosis, exocytosis, endocytic recycling, and transport from/to the Golgi apparatus. Overall, these studies contribute to our understanding of the involvement of PA and DAG in endocytic trafficking, an area of research that is drawing increasing attention in recent years.
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Affiliation(s)
- Shuwei Xie
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
| | - Naava Naslavsky
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
| | - Steve Caplan
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
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Merida I, Andrada E, Gharbi SI, Avila-Flores A. Redundant and specialized roles for diacylglycerol kinases and in the control of T cell functions. Sci Signal 2015; 8:re6. [DOI: 10.1126/scisignal.aaa0974] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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31
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Singh V, Yang J, Cha B, Chen TE, Sarker R, Yin J, Avula LR, Tse M, Donowitz M. Sorting nexin 27 regulates basal and stimulated brush border trafficking of NHE3. Mol Biol Cell 2015; 26:2030-43. [PMID: 25851603 PMCID: PMC4472014 DOI: 10.1091/mbc.e14-12-1597] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 04/01/2015] [Indexed: 12/21/2022] Open
Abstract
In polarized epithelial cells, SNX27 regulates PDZ domain–directed trafficking of NHE3 from endosomes to the plasma membrane and increases the stability of brush border NHE3. This establishes SNX27 as an important regulator of polarized sorting in epithelial cells. Sorting nexin 27 (SNX27) contains a PDZ domain that is phylogenetically related to the PDZ domains of the NHERF proteins. Studies on nonepithelial cells have shown that this protein is located in endosomes, where it regulates trafficking of cargo proteins in a PDZ domain–dependent manner. However, the role of SNX27 in trafficking of cargo proteins in epithelial cells has not been adequately explored. Here we show that SNX27 directly interacts with NHE3 (C-terminus) primarily through the SNX27 PDZ domain. A combination of knockdown and reconstitution experiments with wild type and a PDZ domain mutant (GYGF → GAGA) of SNX27 demonstrate that the PDZ domain of SNX27 is required to maintain basal NHE3 activity and surface expression of NHE3 in polarized epithelial cells. Biotinylation-based recycling and degradation studies in intestinal epithelial cells show that SNX27 is required for the exocytosis (not endocytosis) of NHE3 from early endosome to plasma membrane. SNX27 is also required to regulate the retention of NHE3 on the plasma membrane. The findings of the present study extend our understanding of PDZ-mediated recycling of cargo proteins from endosome to plasma membrane in epithelial cells.
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Affiliation(s)
- Varsha Singh
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Jianbo Yang
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Boyoung Cha
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Tiane-e Chen
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Rafiquel Sarker
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Jianyi Yin
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Leela Rani Avula
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Ming Tse
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Mark Donowitz
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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Wang X, Huang T, Zhao Y, Zheng Q, Thompson RC, Bu G, Zhang YW, Hong W, Xu H. Sorting nexin 27 regulates Aβ production through modulating γ-secretase activity. Cell Rep 2014; 9:1023-33. [PMID: 25437557 DOI: 10.1016/j.celrep.2014.09.037] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Revised: 08/04/2014] [Accepted: 09/18/2014] [Indexed: 12/14/2022] Open
Abstract
Patients with Down syndrome (DS) invariably develop Alzheimer's disease (AD) pathology in their 40s. We have recently found that overexpression of a chromosome 21-encoded microRNA-155 results in decreased levels of the membrane trafficking component, SNX27, diminishing glutamate receptor recycling and thereby impairing synaptic functions in DS. Here, we report a function of SNX27 in regulating β-amyloid (Aβ) generation by modulating γ-secretase activity. Downregulation of SNX27 using RNAi increased Aβ production, whereas overexpression of full-length SNX27, but not SNX27ΔPDZ, reversed the RNAi-mediated Aβ elevation. Moreover, genetic deletion of Snx27 promoted Aβ production and neuronal loss, whereas overexpression of SNX27 using an adeno-associated viral (AAV) vector reduced hippocampal Aβ levels in a transgenic AD mouse model. SNX27 associates with the γ-secretase complex subunit presenilin 1; this interaction dissociates the γ-secretase complex, thus decreasing its proteolytic activity. Our study establishes a molecular mechanism for Aβ-dependent pathogenesis in both DS and AD.
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Affiliation(s)
- Xin Wang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen 361005, China; Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Timothy Huang
- Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Yingjun Zhao
- Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Qiuyang Zheng
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen 361005, China; Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Robert C Thompson
- Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Guojun Bu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen 361005, China
| | - Yun-wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen 361005, China; Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Wanjin Hong
- Institute for Biomedical Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen 361005, China; Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore 138673, Singapore
| | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen 361005, China; Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA.
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Sorting Nexin 27 regulates basal and activity-dependent trafficking of AMPARs. Proc Natl Acad Sci U S A 2014; 111:11840-5. [PMID: 25071192 DOI: 10.1073/pnas.1412415111] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Activity-dependent changes in synaptic strength have long been postulated as cellular correlates of learning and memory. Long-term potentiation (LTP), a well characterized form of synaptic plasticity, is often expressed as an increase in the number of postsynaptic AMPA-type glutamate receptors (AMPARs). Although the precise molecular mechanisms governing LTP remain elusive, this study identifies one member of the sorting nexin family, Sorting Nexin 27 (SNX27), as a critical component in this process. The ability of sorting nexins to bind specific phospholipids as well as their propensity to form protein-protein complexes, points to a role for these proteins in membrane trafficking and protein sorting. Here, we demonstrate that SNX27 binds to AMPARs, and that this interaction is regulated in an activity-dependent manner. Furthermore, we provide evidence that SNX27 is synaptically enriched and its level of expression regulates targeting of AMPARs to the neuronal surface. Loss of SNX27 abolishes recruitment of surface AMPARs during chemical LTP. Collectively, our data suggest a role for SNX27 in modulating synaptic plasticity through regulated interaction with AMPARs.
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van Weering JRT, Cullen PJ. Membrane-associated cargo recycling by tubule-based endosomal sorting. Semin Cell Dev Biol 2014; 31:40-7. [PMID: 24641888 DOI: 10.1016/j.semcdb.2014.03.015] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 03/09/2014] [Accepted: 03/11/2014] [Indexed: 01/27/2023]
Abstract
The endosome system is a collection of organelles that sort membrane-associated proteins and lipids for lysosomal degradation or recycling back to their target organelle. Recycling cargo is captured in a network of membrane tubules emanating from endosomes where tubular carriers pinch off. These tubules are formed and stabilized through the scaffolding properties of cytosolic Bin/Amphiphysin/Rvs (BAR) proteins that comprise phosphoinositide-detecting moieties, recruiting these proteins to specific endosomal membrane areas. These include the protein family of sorting nexins that remodel endosome membrane into tubules by an evolutionary conserved mechanism of dimerization, local membrane curvature detection/induction and oligomerization. How the formation of such a tubular membrane carrier is coordinated with cargo capture is largely unknown. The tubular structure of the membrane carriers could sequester membrane-bound cargo through an iterative mechanism of geometric sorting. Furthermore, the recent identification of cargo adaptors for the endosome protein sorting complex retromer has expanded the sorting signals that retrieve specific sets of cargo away from lysosomal degradation through distinct membrane trafficking pathways.
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Affiliation(s)
- Jan R T van Weering
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University and VU Medical Center, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
| | - Peter J Cullen
- Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, United Kingdom
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35
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Ishisaka M, Hara H. The Roles of Diacylglycerol Kinases in the Central Nervous System: Review of Genetic Studies in Mice. J Pharmacol Sci 2014; 124:336-43. [DOI: 10.1254/jphs.13r07cr] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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36
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You JS, Lincoln HC, Kim CR, Frey JW, Goodman CA, Zhong XP, Hornberger TA. The role of diacylglycerol kinase ζ and phosphatidic acid in the mechanical activation of mammalian target of rapamycin (mTOR) signaling and skeletal muscle hypertrophy. J Biol Chem 2013; 289:1551-63. [PMID: 24302719 DOI: 10.1074/jbc.m113.531392] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The activation of mTOR signaling is essential for mechanically induced changes in skeletal muscle mass, and previous studies have suggested that mechanical stimuli activate mTOR (mammalian target of rapamycin) signaling through a phospholipase D (PLD)-dependent increase in the concentration of phosphatidic acid (PA). Consistent with this conclusion, we obtained evidence which further suggests that mechanical stimuli utilize PA as a direct upstream activator of mTOR signaling. Unexpectedly though, we found that the activation of PLD is not necessary for the mechanically induced increases in PA or mTOR signaling. Motivated by this observation, we performed experiments that were aimed at identifying the enzyme(s) that promotes the increase in PA. These experiments revealed that mechanical stimulation increases the concentration of diacylglycerol (DAG) and the activity of DAG kinases (DGKs) in membranous structures. Furthermore, using knock-out mice, we determined that the ζ isoform of DGK (DGKζ) is necessary for the mechanically induced increase in PA. We also determined that DGKζ significantly contributes to the mechanical activation of mTOR signaling, and this is likely driven by an enhanced binding of PA to mTOR. Last, we found that the overexpression of DGKζ is sufficient to induce muscle fiber hypertrophy through an mTOR-dependent mechanism, and this event requires DGKζ kinase activity (i.e. the synthesis of PA). Combined, these results indicate that DGKζ, but not PLD, plays an important role in mechanically induced increases in PA and mTOR signaling. Furthermore, this study suggests that DGKζ could be a fundamental component of the mechanism(s) through which mechanical stimuli regulate skeletal muscle mass.
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Affiliation(s)
- Jae-Sung You
- From the Program in Cellular and Molecular Biology and
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37
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Abstract
Diacylglycerol (DAG), a second messenger generated by phospholipase Cγ1 activity upon engagement of a T-cell receptor, triggers several signaling cascades that play important roles in T cell development and function. A family of enzymes called DAG kinases (DGKs) catalyzes the phosphorylation of DAG to phosphatidic acid, acting as a braking mechanism that terminates DAG-mediated signals. Two DGK isoforms, α and ζ, are expressed predominantly in T cells and synergistically regulate the development of both conventional αβ T cells and invariant natural killer T cells in the thymus. In mature T cells, the activity of these DGK isoforms aids in the maintenance of self-tolerance by preventing T-cell hyperactivation upon T cell receptor stimulation and by promoting T-cell anergy. In CD8 cells, reduced DGK activity is associated with enhanced primary responses against viruses and tumors. Recent work also has established an important role for DGK activity at the immune synapse and identified partners that modulate DGK function. In addition, emerging evidence points to previously unappreciated roles for DGK function in directional secretion and T-cell adhesion. This review describes the multitude of roles played by DGKs in T cell development and function and emphasizes recent advances in the field.
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Affiliation(s)
- Sruti Krishna
- Department of Pediatrics, Division of Allergy and Immunology and Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
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38
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Steinberg F, Gallon M, Winfield M, Thomas EC, Bell AJ, Heesom KJ, Tavaré JM, Cullen PJ. A global analysis of SNX27-retromer assembly and cargo specificity reveals a function in glucose and metal ion transport. Nat Cell Biol 2013; 15:461-71. [PMID: 23563491 PMCID: PMC4052425 DOI: 10.1038/ncb2721] [Citation(s) in RCA: 386] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 03/01/2013] [Indexed: 02/08/2023]
Abstract
The PDZ-domain-containing sorting nexin 27 (SNX27) promotes recycling of internalized transmembrane proteins from endosomes to the plasma membrane by linking PDZ-dependent cargo recognition to retromer-mediated transport. Here, we employed quantitative proteomics of the SNX27 interactome and quantification of the surface proteome of SNX27- and retromer-suppressed cells to dissect the assembly of the SNX27 complex and provide an unbiased global view of SNX27-mediated sorting. Over 100 cell surface proteins, many of which interact with SNX27, including the glucose transporter GLUT1, the Menkes disease copper transporter ATP7A, various zinc and amino acid transporters, and numerous signalling receptors, require SNX27-retromer to prevent lysosomal degradation and maintain surface levels. Furthermore, we establish that direct interaction of the SNX27 PDZ domain with the retromer subunit VPS26 is necessary and sufficient to prevent lysosomal entry of SNX27 cargo. Our data identify the SNX27-retromer as a major endosomal recycling hub required to maintain cellular nutrient homeostasis.
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Affiliation(s)
- Florian Steinberg
- The Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
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Joshi RP, Koretzky GA. Diacylglycerol kinases: regulated controllers of T cell activation, function, and development. Int J Mol Sci 2013; 14:6649-73. [PMID: 23531532 PMCID: PMC3645659 DOI: 10.3390/ijms14046649] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 03/07/2013] [Accepted: 03/14/2013] [Indexed: 01/22/2023] Open
Abstract
Diacylglycerol kinases (DGKs) are a diverse family of enzymes that catalyze the conversion of diacylglycerol (DAG), a crucial second messenger of receptor-mediated signaling, to phosphatidic acid (PA). Both DAG and PA are bioactive molecules that regulate a wide set of intracellular signaling proteins involved in innate and adaptive immunity. Clear evidence points to a critical role for DGKs in modulating T cell activation, function, and development. More recently, studies have elucidated factors that control DGK function, suggesting an added complexity to how DGKs act during signaling. This review summarizes the available knowledge of the function and regulation of DGK isoforms in signal transduction with a particular focus on T lymphocytes.
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Affiliation(s)
- Rohan P. Joshi
- Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, PA 19104, USA; E-Mail:
| | - Gary A. Koretzky
- Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, PA 19104, USA; E-Mail:
- Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-215-746-5522; Fax: +1-215-746-5525
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40
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Balana B, Bahima L, Bodhinathan K, Taura JJ, Taylor NM, Nettleton MY, Ciruela F, Slesinger PA. Ras-association domain of sorting Nexin 27 is critical for regulating expression of GIRK potassium channels. PLoS One 2013; 8:e59800. [PMID: 23536889 PMCID: PMC3607560 DOI: 10.1371/journal.pone.0059800] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 02/19/2013] [Indexed: 12/25/2022] Open
Abstract
G protein-gated inwardly rectifying potassium (GIRK) channels play an important role in regulating neuronal excitability. Sorting nexin 27b (SNX27b), which reduces surface expression of GIRK channels through a PDZ domain interaction, contains a putative Ras-association (RA) domain with unknown function. Deleting the RA domain in SNX27b (SNX27b-ΔRA) prevents the down-regulation of GIRK2c/GIRK3 channels. Similarly, a point mutation (K305A) in the RA domain disrupts regulation of GIRK2c/GIRK3 channels and reduces H-Ras binding in vitro. Finally, the dominant-negative H-Ras (S17N) occludes the SNX27b-dependent decrease in surface expression of GIRK2c/GIRK3 channels. Thus, the presence of a functional RA domain and the interaction with Ras-like G proteins comprise a novel mechanism for modulating SNX27b control of GIRK channel surface expression and cellular excitability.
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Affiliation(s)
- Bartosz Balana
- Peptide Biology Laboratories, The Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Laia Bahima
- Peptide Biology Laboratories, The Salk Institute for Biological Studies, La Jolla, California, United States of America
- Unitat de Farmacologia, Departament de Patologia i Terapèutica Experimental, University of Barcelona, Barcelona, Spain
| | - Karthik Bodhinathan
- Peptide Biology Laboratories, The Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Jaume J. Taura
- Peptide Biology Laboratories, The Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Natalie M. Taylor
- Peptide Biology Laboratories, The Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Margaret Y. Nettleton
- Peptide Biology Laboratories, The Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament de Patologia i Terapèutica Experimental, University of Barcelona, Barcelona, Spain
- * E-mail: (PS); (FC)
| | - Paul A. Slesinger
- Peptide Biology Laboratories, The Salk Institute for Biological Studies, La Jolla, California, United States of America
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail: (PS); (FC)
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41
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Tu-Sekine B, Raben DM. Dual regulation of diacylglycerol kinase (DGK)-θ: polybasic proteins promote activation by phospholipids and increase substrate affinity. J Biol Chem 2012; 287:41619-27. [PMID: 23091060 DOI: 10.1074/jbc.m112.404855] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Diacylglycerol kinases are important mediators of lipid signaling cascades, and insight into their regulation is of increasing interest. Using purified DGK-θ, we show that this isoform is subject to dual regulation and that the previously characterized stimulation by acidic phospholipids is dependent on the presence of a positively charged protein or peptide. Polybasic cofactors lowered the K(m) for diacylglycerol at the membrane surface (K(m)((surf))), and worked synergistically with acidic phospholipids to increase activity 10- to 30-fold, suggesting that the purified enzyme is autoinhibited. Vesicle pulldown studies showed that acidic phospholipids recruit polybasic cofactors to the vesicle surface but have little effect on the membrane association of DGK-θ, suggesting that a triad of enzyme, acidic lipid and basic protein are necessary for interfacial activity. Importantly, these data demonstrate that the interfacial association and catalytic activity of DGK-θ are independently regulated. Finally, we show that DGK-θ directly interacts with, and is activated by, basic proteins such as histone H1 and Tau with nm affinity, consistent with a potential role for a polybasic protein or protein domain in the activation of this enzyme.
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Affiliation(s)
- Becky Tu-Sekine
- Department of Biological Chemistry, The Johns Hopkins School of Medicine, Baltimore, Maryland 20120, USA
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Rainero E, Caswell PT, Muller PAJ, Grindlay J, McCaffrey MW, Zhang Q, Wakelam MJO, Vousden KH, Graziani A, Norman JC. Diacylglycerol kinase α controls RCP-dependent integrin trafficking to promote invasive migration. ACTA ACUST UNITED AC 2012; 196:277-95. [PMID: 22270919 PMCID: PMC3265946 DOI: 10.1083/jcb.201109112] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Phosphatidic acid generation by DGK-α is essential for the localization of Rab11-coupling protein to invasive pseudopods and subsequent invasive migration by tumor cells. Inhibition of αvβ3 integrin or expression of oncogenic mutants of p53 promote invasive cell migration by enhancing endosomal recycling of α5β1 integrin under control of the Rab11 effector Rab-coupling protein (RCP). In this paper, we show that diacylglycerol kinase α (DGK-α), which phosphorylates diacylglycerol to phosphatidic acid (PA), was required for RCP to be mobilized to and tethered at the tips of invasive pseudopods and to allow RCP-dependent α5β1 recycling and the resulting invasiveness of tumor cells. Expression of a constitutive-active mutant of DGK-α drove RCP-dependent invasion in the absence of mutant p53 expression or αvβ3 inhibition, and conversely, an RCP mutant lacking the PA-binding C2 domain was not capable of being tethered at pseudopod tips. These data demonstrate that generation of PA downstream of DGK-α is essential to connect expression of mutant p53s or inhibition of αvβ3 to RCP and for this Rab11 effector to drive the trafficking of α5β1 that is required for tumor cell invasion through three-dimensional matrices.
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Affiliation(s)
- Elena Rainero
- Beatson Institute for Cancer Research, G61 1BD Glasgow, Scotland, UK
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43
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Abstract
The endo-lysosomal system is an interconnected tubulo-vesicular network that acts as a sorting station to process and distribute internalised cargo. This network accepts cargoes from both the plasma membrane and the biosynthetic pathway, and directs these cargos either towards the lysosome for degradation, the peri-nuclear recycling endosome for return to the cell surface, or to the trans-Golgi network. These intracellular membranes are variously enriched in different phosphoinositides that help to shape compartmental identity. These lipids act to localise a number of phosphoinositide-binding proteins that function as sorting machineries to regulate endosomal cargo sorting. Herein we discuss regulation of these machineries by phosphoinositides and explore how phosphoinositide-switching contributes toward sorting decisions made at this platform.
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Affiliation(s)
- Peter J Cullen
- Henry Wellcome Integrated Signaling Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, BS8 1TD, Bristol, United Kingdom,
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Rincón E, Gharbi SI, Santos-Mendoza T, Mérida I. Diacylglycerol kinase ζ: At the crossroads of lipid signaling and protein complex organization. Prog Lipid Res 2012; 51:1-10. [DOI: 10.1016/j.plipres.2011.10.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Insights into the PX (phox-homology) domain and SNX (sorting nexin) protein families: structures, functions and roles in disease. Biochem J 2011; 441:39-59. [DOI: 10.1042/bj20111226] [Citation(s) in RCA: 212] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The mammalian genome encodes 49 proteins that possess a PX (phox-homology) domain, responsible for membrane attachment to organelles of the secretory and endocytic system via binding of phosphoinositide lipids. The PX domain proteins, most of which are classified as SNXs (sorting nexins), constitute an extremely diverse family of molecules that play varied roles in membrane trafficking, cell signalling, membrane remodelling and organelle motility. In the present review, we present an overview of the family, incorporating recent functional and structural insights, and propose an updated classification of the proteins into distinct subfamilies on the basis of these insights. Almost all PX domain proteins bind PtdIns3P and are recruited to early endosomal membranes. Although other specificities and localizations have been reported for a select few family members, the molecular basis for binding to other lipids is still not clear. The PX domain is also emerging as an important protein–protein interaction domain, binding endocytic and exocytic machinery, transmembrane proteins and many other molecules. A comprehensive survey of the molecular interactions governed by PX proteins highlights the functional diversity of the family as trafficking cargo adaptors and membrane-associated scaffolds regulating cell signalling. Finally, we examine the mounting evidence linking PX proteins to different disorders, in particular focusing on their emerging importance in both pathogen invasion and amyloid production in Alzheimer's disease.
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Baldanzi G, Pighini A, Bettio V, Rainero E, Traini S, Chianale F, Porporato PE, Filigheddu N, Mesturini R, Song S, Schweighoffer T, Patrussi L, Baldari CT, Zhong XP, van Blitterswijk WJ, Sinigaglia F, Nichols KE, Rubio I, Parolini O, Graziani A. SAP-mediated inhibition of diacylglycerol kinase α regulates TCR-induced diacylglycerol signaling. THE JOURNAL OF IMMUNOLOGY 2011; 187:5941-51. [PMID: 22048771 DOI: 10.4049/jimmunol.1002476] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Diacylglycerol kinases (DGKs) metabolize diacylglycerol to phosphatidic acid. In T lymphocytes, DGKα acts as a negative regulator of TCR signaling by decreasing diacylglycerol levels and inducing anergy. In this study, we show that upon costimulation of the TCR with CD28 or signaling lymphocyte activation molecule (SLAM), DGKα, but not DGKζ, exits from the nucleus and undergoes rapid negative regulation of its enzymatic activity. Inhibition of DGKα is dependent on the expression of SAP, an adaptor protein mutated in X-linked lymphoproliferative disease, which is essential for SLAM-mediated signaling and contributes to TCR/CD28-induced signaling and T cell activation. Accordingly, overexpression of SAP is sufficient to inhibit DGKα, whereas SAP mutants unable to bind either phospho-tyrosine residues or SH3 domain are ineffective. Moreover, phospholipase C activity and calcium, but not Src-family tyrosine kinases, are also required for negative regulation of DGKα. Finally, inhibition of DGKα in SAP-deficient cells partially rescues defective TCR/CD28 signaling, including Ras and ERK1/2 activation, protein kinase C membrane recruitment, induction of NF-AT transcriptional activity, and IL-2 production. Thus SAP-mediated inhibition of DGKα sustains diacylglycerol signaling, thereby regulating T cell activation, and it may represent a novel pharmacological strategy for X-linked lymphoproliferative disease treatment.
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Affiliation(s)
- Gianluca Baldanzi
- Department of Clinical and Experimental Medicine, University A. Avogadro of Piemonte Orientale, 28100 Novara, Italy.
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Gharbi SI, Rincón E, Avila-Flores A, Torres-Ayuso P, Almena M, Cobos MA, Albar JP, Mérida I. Diacylglycerol kinase ζ controls diacylglycerol metabolism at the immunological synapse. Mol Biol Cell 2011; 22:4406-14. [PMID: 21937721 PMCID: PMC3216665 DOI: 10.1091/mbc.e11-03-0247] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
DGKα and DGKζ negatively regulate the DAG/RasGRP1/Ras pathway in T cells. Study of the specific contribution of each isoform to DAG metabolism during immune synapse formation by use of a combination of RNAi and videomicroscopy techniques identifies DGKζ as mainly responsible for DAG consumption at the immunological synapse. Diacylglycerol (DAG) generation at the T cell immunological synapse (IS) determines the correct activation of antigen-specific immune responses. DAG kinases (DGKs) α and ζ act as negative regulators of DAG-mediated signals by catalyzing DAG conversion to phosphatidic acid (PA). Nonetheless, the specific input of each enzyme and their spatial regulation during IS formation remain uncharacterized. Here we report recruitment of endogenous DGKα and DGKζ to the T cell receptor (TCR) complex following TCR/CD28 engagement. Specific DGK gene silencing shows that PA production at the activated complex depends mainly on DGKζ, indicating functional differences between these proteins. DGKζ kinase activity at the TCR is enhanced by phorbol-12-myristate-13-acetate cotreatment, suggesting DAG-mediated regulation of DGKζ responsiveness. We used GFP-DGKζ and -DGKα chimeras to assess translocation dynamics during IS formation. Only GFP-DGKζ translocated rapidly to the plasma membrane at early stages of IS formation, independent of enzyme activity. Finally, use of a fluorescent DAG sensor confirmed rapid, sustained DAG accumulation at the IS and allowed us to directly correlate membrane translocation of active DGKζ with DAG consumption at the IS. This study highlights a DGKζ-specific function for local DAG metabolism at the IS and offers new clues to its mode of regulation.
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Affiliation(s)
- Severine I Gharbi
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, E-28049 Madrid, Spain
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Valdes JL, Tang J, McDermott MI, Kuo JC, Zimmerman SP, Wincovitch SM, Waterman CM, Milgram SL, Playford MP. Sorting nexin 27 protein regulates trafficking of a p21-activated kinase (PAK) interacting exchange factor (β-Pix)-G protein-coupled receptor kinase interacting protein (GIT) complex via a PDZ domain interaction. J Biol Chem 2011; 286:39403-16. [PMID: 21926430 DOI: 10.1074/jbc.m111.260802] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Sorting nexin 27 (SNX27) is a 62-kDa protein localized to early endosomes and known to regulate the intracellular trafficking of ion channels and receptors. In addition to a PX domain, SNX27 is the only sorting family member that contains a PDZ domain. To identify novel SNX27-PDZ binding partners, we performed a proteomic screen in mouse principal kidney cortical collecting duct cells using a GST-SNX27 fusion construct as bait. We found that β-Pix (p21-activated kinase-interactive exchange factor), a guanine nucleotide exchange factor for the Rho family of small GTPases known to regulate cell motility directly interacted with SNX27. The association of β-Pix and SNX27 is specific for β-Pix isoforms terminating in the type-1 PDZ binding motif (ETNL). In the same screen we also identified Git1/2 as a potential SNX27 interacting protein. The interaction between SNX27 and Git1/2 is indirect and mediated by β-Pix. Furthermore, we show recruitment of the β-Pix·Git complex to endosomal sites in a SNX27-dependent manner. Finally, migration assays revealed that depletion of SNX27 from HeLa and mouse principal kidney cortical collecting duct cells significantly decreases cell motility. We propose a model by which SNX27 regulates trafficking of β-Pix to focal adhesions and thereby influences cell motility.
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Affiliation(s)
- Julie L Valdes
- Cell Biology and Physiology Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20982, USA
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Ghai R, Collins BM. PX-FERM proteins: A link between endosomal trafficking and signaling? Small GTPases 2011; 2:259-263. [PMID: 22292128 DOI: 10.4161/sgtp.2.5.17276] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 07/13/2011] [Accepted: 07/15/2011] [Indexed: 01/08/2023] Open
Abstract
Endosomes are the primary organelle where decisions are made as to whether endocytosed proteins will be sorted into degradative trafficking pathways or recycled back to the plasma membrane. This balance between cellular uptake and recycling regulates the plasma membrane composition and is therefore critical for many cellular processes such as nutrient uptake, neuronal transmission and cell migration.1 In addition to its well-known role in membrane trafficking, the endosome is increasingly being recognized as a critical cellular domain for regulated cell signaling. We recently showed that several proteins that regulate endosomal recycling, SNX17, SNX27 and SNX31 are structurally and functionally related.2 These proteins use an unusual FERM domain to bind specific endosomal cargo molecules, and most interestingly, we also found that these proteins use the same FERM domain to associate with the activated Ras small GTPase. Here we speculate on the potential dual role of the PX-FERM proteins in endosomal transport and as scaffolds that may be involved in endosomal Ras signaling processes.
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Affiliation(s)
- Rajesh Ghai
- Institute for Molecular Bioscience; University of Queensland; St. Lucia, Queensland Australia
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Shaping up the membrane: diacylglycerol coordinates spatial orientation of signaling. Trends Biochem Sci 2011; 36:593-603. [PMID: 21798744 DOI: 10.1016/j.tibs.2011.06.005] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Revised: 06/21/2011] [Accepted: 06/23/2011] [Indexed: 11/23/2022]
Abstract
Diacylglycerol signals by binding and activating C1 domain-containing proteins expressed principally in neuronal and immune tissues. This restricted expression profile suggests that diacylglycerol-regulated signals are particularly relevant in cell-cell communication processes in which active endocytosis and exocytosis take place. Not surprisingly, various experimental approaches have demonstrated a crucial role for diacylglycerol effectors and metabolizing enzymes in the control of immune responses, neuron communication and phagocytosis. Current research delineates a scenario in which coordinated decoding of diacylglycerol signals is translated into complex biological responses such as neuronal plasticity, T cell development or cytolytic killing. Diacylglycerol functions reach maximal diversity in these highly specialized systems in which signal intensity directly regulates distinct biological outcomes. This review brings together the most recent studies, emphasizing the contribution of compartmentalized DAG metabolism to orientated signaling events.
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