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Girard M, Bellefeuille SD, Eiselt É, Arguin G, Longpré JM, Sarret P, Gendron FP. Ligand-dependent intracellular trafficking of the G protein-coupled P2Y 6 receptor. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119476. [PMID: 37059189 DOI: 10.1016/j.bbamcr.2023.119476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 03/28/2023] [Accepted: 04/05/2023] [Indexed: 04/16/2023]
Abstract
Endosomal trafficking is intricately linked to G protein-coupled receptors (GPCR) fate and signaling. Extracellular uridine diphosphate (UDP) acts as a signaling molecule by selectively activating the GPCR P2Y6. Despite the recent interest for this receptor in pathologies, such as gastrointestinal and neurological diseases, there is sparse information on the endosomal trafficking of P2Y6 receptors in response to its endogenous agonist UDP and synthetic selective agonist 5-iodo-UDP (MRS2693). Confocal microscopy and cell surface ELISA revealed delayed internalization kinetics in response to MRS2693 vs. UDP stimulation in AD293 and HCT116 cells expressing human P2Y6. Interestingly, UDP induced clathrin-dependent P2Y6 internalization, whereas receptor stimulation by MRS2693 endocytosis appeared to be associated with a caveolin-dependent mechanism. Internalized P2Y6 was associated with Rab4, 5, and 7 positive vesicles independent of the agonist. We have measured a higher frequency of receptor expression co-occurrence with Rab11-vesicles, the trans-Golgi network, and lysosomes in response to MRS2693. Interestingly, a higher agonist concentration reversed the delayed P2Y6 internalization and recycling kinetics in the presence of MRS2693 stimulation without changing its caveolin-dependent internalization. This work showed a ligand-dependent effect affecting the P2Y6 receptor internalization and endosomal trafficking. These findings could guide the development of bias ligands that could influence P2Y6 signaling.
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Affiliation(s)
- Mélissa Girard
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada; Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Canada
| | - Steve Dagenais Bellefeuille
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Émilie Eiselt
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Canada
| | - Guillaume Arguin
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Jean-Michel Longpré
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Canada
| | - Philippe Sarret
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Canada
| | - Fernand-Pierre Gendron
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada; Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Canada.
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Huang J, Tiu AC, Jose PA, Yang J. Sorting nexins: role in the regulation of blood pressure. FEBS J 2023; 290:600-619. [PMID: 34847291 PMCID: PMC9149145 DOI: 10.1111/febs.16305] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 10/13/2021] [Accepted: 11/29/2021] [Indexed: 02/06/2023]
Abstract
Sorting nexins (SNXs) are a family of proteins that regulate cellular cargo sorting and trafficking, maintain intracellular protein homeostasis, and participate in intracellular signaling. SNXs are also important in the regulation of blood pressure via several mechanisms. Aberrant expression and dysfunction of SNXs participate in the dysregulation of blood pressure. Genetic studies show a correlation between SNX gene variants and the response to antihypertensive drugs. In this review, we summarize the progress in SNX-mediated regulation of blood pressure, discuss the potential role of SNXs in the pathophysiology and treatment of hypertension, and propose novel strategies for the medical therapy of hypertension.
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Affiliation(s)
- Juan Huang
- Department of Clinical Nutrition, The Third Affiliated Hospital of Chongqing Medical University, Chongqing 410020, P.R. China
| | - Andrew C. Tiu
- Department of Medicine, Einstein Medical Center Philadelphia, Philadelphia, PA 19141, USA
| | - Pedro A. Jose
- Division of Renal Diseases & Hypertension, Department of Medicine, and Department of Physiology and Pharmacology, The George Washington University School of Medicine & Health Sciences, Washington, DC 20052, USA
| | - Jian Yang
- Department of Clinical Nutrition, The Third Affiliated Hospital of Chongqing Medical University, Chongqing 410020, P.R. China
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3
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Da Graça J, Morel E. Canonical and Non-Canonical Roles of SNX1 and SNX2 in Endosomal Membrane Dynamics. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2023; 6:25152564231217867. [PMID: 38033809 PMCID: PMC10683387 DOI: 10.1177/25152564231217867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 11/07/2023] [Accepted: 11/15/2023] [Indexed: 12/02/2023]
Abstract
Sorting nexins (SNXs) are a family of membrane-binding proteins known to play a critical role in regulating endocytic pathway sorting and endosomal membrane trafficking. Among them, SNX1 and SNX2 are members of the SNX-BAR subfamily and possess a membrane-curvature domain and a phosphoinositide-binding domain, which enables their stabilization at the phosphatidylinositol-3-phosphate (PI3P)-positive surface of endosomes. While their binding to PI3P-positive platforms facilitates interaction with endosomal partners and stabilization at the endosomal membrane, their SNX-BAR region is pivotal for generating membrane tubulation from endosomal compartments. In this context, their primary identified biological roles-and their partnership-are tightly associated with the retromer and endosomal SNX-BAR sorting complex for promoting exit 1 complex trafficking, facilitating the transport of cargoes from early endosomes to the secretory pathway. However, recent literature indicates that these proteins also possess biological functions in other aspects of endosomal features and sorting processes. Notably, SNX2 has been found to regulate endosome-endoplasmic reticulum (ER) contact sites through its interaction with VAP proteins at the ER membrane. Furthermore, data from our laboratory show that SNX1 and SNX2 are involved in the tubulation of early endosomes toward ER sites associated with autophagy initiation during starvation. These findings shed light on a novel role of SNXs in inter-organelle tethering and communication. In this concise review, we will explore the non-retromer functions of SNX1 and SNX2, specifically focusing on their involvement in endosomal membrane dynamics during stress sensing and autophagy-associated processes.
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Affiliation(s)
- Juliane Da Graça
- Université Paris Cité, INSERM UMR-S1151, CNRS UMR-S8253, Institut Necker Enfants Malades, Paris, France
| | - Etienne Morel
- Université Paris Cité, INSERM UMR-S1151, CNRS UMR-S8253, Institut Necker Enfants Malades, Paris, France
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4
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Law KC, Chung KK, Zhuang X. An Update on Coat Protein Complexes for Vesicle Formation in Plant Post-Golgi Trafficking. FRONTIERS IN PLANT SCIENCE 2022; 13:826007. [PMID: 35283904 PMCID: PMC8905187 DOI: 10.3389/fpls.2022.826007] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/11/2022] [Indexed: 05/13/2023]
Abstract
Endomembrane trafficking is an evolutionarily conserved process for all eukaryotic organisms. It is a fundamental and essential process for the transportation of proteins, lipids, or cellular metabolites. The aforementioned cellular components are sorted across multiple membrane-bounded organelles. In plant cells, the endomembrane mainly consists of the nuclear envelope, endoplasmic reticulum (ER), Golgi apparatus, trans-Golgi network or early endosome (TGN/EE), prevacuolar compartments or multivesicular bodies (PVCs/MVBs), and vacuole. Among them, Golgi apparatus and TGN represent two central sorting intermediates for cargo secretion and recycling from other compartments by anterograde or retrograde trafficking. Several protein sorting machineries have been identified to function in these pathways for cargo recognition and vesicle assembly. Exciting progress has been made in recent years to provide novel insights into the sorting complexes and also the underlying sorting mechanisms in plants. Here, we will highlight the recent findings for the adaptor protein (AP) complexes, retromer, and retriever complexes, and also their functions in the related coated vesicle formation in post-Golgi trafficking.
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Affiliation(s)
| | | | - Xiaohong Zhuang
- Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, Hong Kong SAR, China
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5
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Degrandmaison J, Grisé O, Parent JL, Gendron L. Differential barcoding of opioid receptors trafficking. J Neurosci Res 2021; 100:99-128. [PMID: 34559903 DOI: 10.1002/jnr.24949] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 07/25/2021] [Accepted: 08/05/2021] [Indexed: 11/09/2022]
Abstract
Over the past several years, studies have highlighted the δ-opioid receptor (DOPr) as a promising therapeutic target for chronic pain management. While exhibiting milder undesired effects than most currently prescribed opioids, its specific agonists elicit effective analgesic responses in numerous animal models of chronic pain, including inflammatory, neuropathic, diabetic, and cancer-related pain. However, as compared with the extensively studied μ-opioid receptor, the molecular mechanisms governing its trafficking remain elusive. Recent advances have denoted several significant particularities in the regulation of DOPr intracellular routing, setting it apart from the other members of the opioid receptor family. Although they share high homology, each opioid receptor subtype displays specific amino acid patterns potentially involved in the regulation of its trafficking. These precise motifs or "barcodes" are selectively recognized by regulatory proteins and therefore dictate several aspects of the itinerary of a receptor, including its anterograde transport, internalization, recycling, and degradation. With a specific focus on the regulation of DOPr trafficking, this review will discuss previously reported, as well as potential novel trafficking barcodes within the opioid and nociceptin/orphanin FQ opioid peptide receptors, and their impact in determining distinct interactomes and physiological responses.
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Affiliation(s)
- Jade Degrandmaison
- Département de Pharmacologie-Physiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Institut de Pharmacologie de Sherbrooke, Centre de Recherche du CHUS, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Quebec Network of Junior Pain Investigators, QC, Canada
| | - Olivier Grisé
- Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Institut de Pharmacologie de Sherbrooke, Centre de Recherche du CHUS, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Jean-Luc Parent
- Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Institut de Pharmacologie de Sherbrooke, Centre de Recherche du CHUS, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Louis Gendron
- Département de Pharmacologie-Physiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Institut de Pharmacologie de Sherbrooke, Centre de Recherche du CHUS, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Quebec Pain Research Network, QC, Canada
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6
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Paterson GG, Young JM, Willson JA, Graham CJ, Dru RC, Lee EW, Torpey GS, Walmsley SR, Chan MV, Warner TD, Baillie JK, Thompson AAR. Hypoxia Modulates Platelet Purinergic Signalling Pathways. Thromb Haemost 2019; 120:253-261. [PMID: 31858521 PMCID: PMC7286126 DOI: 10.1055/s-0039-3400305] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Hypoxia resulting from ascent to high-altitude or pathological states at sea level is known to increase platelet reactivity. Previous work from our group has suggested that this may be adenosine diphosphate (ADP)-specific. Given the clinical importance of drugs targeting ADP pathways, research into the impact of hypoxia on platelet ADP pathways is highly important. METHODS Optimul aggregometry was performed on plasma from 29 lowland residents ascending to 4,700 m, allowing systematic assessment of platelet reactivity in response to several platelet agonists. Aggregometry was also performed in response to ADP in the presence of inhibitors of the two main ADP receptors, P2Y1 and P2Y12 (MRS2500 and cangrelor, respectively). Phosphorylation of vasodilator-stimulated phosphoprotein (VASP), a key determinant of platelet aggregation, was analysed using the VASPFix assay. RESULTS Hypobaric hypoxia significantly reduced the ability of a fixed concentration of cangrelor to inhibit ADP-induced aggregation and increased basal VASP phosphorylation. However, in the absence of P2Y receptor inhibitors, we did not find evidence of increased platelet sensitivity to any of the agonists tested and found reduced sensitivity to thrombin receptor-activating peptide-6 amide. CONCLUSION Our results provide evidence of increased P2Y1 receptor activity at high altitude and suggest down-regulation of the P2Y12 pathway through increased VASP phosphorylation. These changes in ADP pathway activity are of potential therapeutic significance to high-altitude sojourners and hypoxic sea level patients prescribed platelet inhibitors and warrant further investigation.
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Affiliation(s)
- Gordon G Paterson
- APEX (Altitude Physiology Expeditions), Edinburgh, United Kingdom.,Edinburgh Medical School, University of Edinburgh, Edinburgh, United Kingdom
| | - Jason M Young
- APEX (Altitude Physiology Expeditions), Edinburgh, United Kingdom.,Edinburgh Medical School, University of Edinburgh, Edinburgh, United Kingdom
| | - Joseph A Willson
- University of Edinburgh Centre for Inflammation Research, The Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Christopher J Graham
- APEX (Altitude Physiology Expeditions), Edinburgh, United Kingdom.,Edinburgh Medical School, University of Edinburgh, Edinburgh, United Kingdom
| | - Rebecca C Dru
- APEX (Altitude Physiology Expeditions), Edinburgh, United Kingdom.,Edinburgh Medical School, University of Edinburgh, Edinburgh, United Kingdom
| | - Eleanor W Lee
- APEX (Altitude Physiology Expeditions), Edinburgh, United Kingdom.,Edinburgh Medical School, University of Edinburgh, Edinburgh, United Kingdom
| | - Greig S Torpey
- APEX (Altitude Physiology Expeditions), Edinburgh, United Kingdom.,Edinburgh Medical School, University of Edinburgh, Edinburgh, United Kingdom
| | - Sarah R Walmsley
- University of Edinburgh Centre for Inflammation Research, The Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Melissa V Chan
- Centre for Immunobiology, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Timothy D Warner
- Centre for Immunobiology, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - John Kenneth Baillie
- APEX (Altitude Physiology Expeditions), Edinburgh, United Kingdom.,Division of Genetics and Genomics, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom.,Department of Anaesthesia, Critical Care and Pain Medicine, Royal Infirmary of Edinburgh, NHS Lothian, Edinburgh, United Kingdom
| | - Alfred Arthur Roger Thompson
- APEX (Altitude Physiology Expeditions), Edinburgh, United Kingdom.,Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
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7
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A Critical Role for Sorting Nexin 1 in the Trafficking of Metabotropic Glutamate Receptors. J Neurosci 2018; 38:8605-8620. [PMID: 30143569 DOI: 10.1523/jneurosci.0454-18.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 07/22/2018] [Accepted: 08/16/2018] [Indexed: 11/21/2022] Open
Abstract
Group I metabotropic glutamate receptors (mGluRs) function as modulators of neuronal physiology and they have also been implicated in various neuropsychiatric disorders. Trafficking of mGluRs plays important roles in controlling the precise localization of these receptors at specific region of the cell, as well as it regulates the activity of these receptors. Despite this obvious significance, we know very little about the cellular machineries that control the trafficking of these receptors in the CNS. Sorting nexin 1 (SNX1) has been shown to regulate the endosomal sorting of few cell surface receptors either to lysosomes where they are downregulated or back to the cell surface. Using "molecular replacement" approach in hippocampal neurons derived from mice of both sexes, we show here that SNX1 plays critical role in the trafficking of mGluR1, a member of the group I mGluR family. Overexpression of dominant-negative SNX1 or knockdown of endogenous SNX1 resulted in the rapid recycling of the receptor. Importantly, recycling via the rapid recycling route, did not allow the resensitization of the receptors. Our data suggest that both, N-terminal and C-terminal region of SNX1 play critical role in the normal trafficking of the receptor. In addition, we also show here that SNX1 regulates the trafficking of mGluR1 through the interaction with Hrs (hepatocyte growth factor-regulated tyrosine kinase substrate), a protein that has been implicated in both signaling and vesicular trafficking. Thus, these studies reveal a mechanistic role of SNX1 in the trafficking of group I mGluRs and its physiological implications.SIGNIFICANCE STATEMENT Group I mGluRs are activated by the neurotransmitter glutamate in the CNS, and play various important roles in the brain. Similar to many other receptors, trafficking plays crucial roles in controlling the precise localization as well as activity of these receptors. Despite this obvious significance very little is known about the cellular machineries that control the trafficking of these receptors. We demonstrate here, that SNX1 plays a critical role in the trafficking of mGluR1, a member of the group I mGluR family. SNX1-mediated trafficking is critical for the resensitization of the receptor. SNX1 controls the trafficking of the receptor through the interaction with another protein, Hrs. The results suggest a role for SNX1 in the regulation of group I mGluRs.
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8
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Buenaventura T, Kanda N, Douzenis PC, Jones B, Bloom SR, Chabosseau P, Corrêa IR, Bosco D, Piemonti L, Marchetti P, Johnson PR, Shapiro AMJ, Rutter GA, Tomas A. A Targeted RNAi Screen Identifies Endocytic Trafficking Factors That Control GLP-1 Receptor Signaling in Pancreatic β-Cells. Diabetes 2018; 67:385-399. [PMID: 29284659 DOI: 10.2337/db17-0639] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Accepted: 12/19/2017] [Indexed: 11/13/2022]
Abstract
The glucagon-like peptide 1 (GLP-1) receptor (GLP-1R) is a key target for type 2 diabetes (T2D) treatment. Because endocytic trafficking of agonist-bound receptors is one of the most important routes for regulation of receptor signaling, a better understanding of this process may facilitate the development of new T2D therapeutic strategies. Here, we screened 29 proteins with known functions in G protein-coupled receptor trafficking for their role in GLP-1R potentiation of insulin secretion in pancreatic β-cells. We identify five (clathrin, dynamin1, AP2, sorting nexins [SNX] SNX27, and SNX1) that increase and four (huntingtin-interacting protein 1 [HIP1], HIP14, GASP-1, and Nedd4) that decrease insulin secretion from murine insulinoma MIN6B1 cells in response to the GLP-1 analog exendin-4. The roles of HIP1 and the endosomal SNX1 and SNX27 were further characterized in mouse and human β-cell lines and human islets. While HIP1 was required for the coupling of cell surface GLP-1R activation with clathrin-dependent endocytosis, the SNXs were found to control the balance between GLP-1R plasma membrane recycling and lysosomal degradation and, in doing so, determine the overall β-cell incretin responses. We thus identify key modulators of GLP-1R trafficking and signaling that might provide novel targets to enhance insulin secretion in T2D.
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Affiliation(s)
- Teresa Buenaventura
- Section of Cell Biology and Functional Genomics and Pancreatic Islet Biology and Diabetes Consortium, Imperial College London, London, U.K
| | - Nisha Kanda
- Section of Cell Biology and Functional Genomics and Pancreatic Islet Biology and Diabetes Consortium, Imperial College London, London, U.K
| | - Phoebe C Douzenis
- Section of Cell Biology and Functional Genomics and Pancreatic Islet Biology and Diabetes Consortium, Imperial College London, London, U.K
| | - Ben Jones
- Section of Investigative Medicine, Imperial College London, London, U.K
| | - Stephen R Bloom
- Section of Investigative Medicine, Imperial College London, London, U.K
| | - Pauline Chabosseau
- Section of Cell Biology and Functional Genomics and Pancreatic Islet Biology and Diabetes Consortium, Imperial College London, London, U.K
| | | | - Domenico Bosco
- Department of Surgery, University of Geneva, Geneva, Switzerland
| | - Lorenzo Piemonti
- Diabetes Research Institute, San Raffaele Scientific Institute, Milan, Italy
- Vita-Salute San Raffaele University, Milan, Italy
| | - Piero Marchetti
- Department of Clinical and Experimental Medicine, Islet Cell Laboratory, University of Pisa, Pisa, Italy
| | - Paul R Johnson
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, U.K
| | - A M James Shapiro
- Clinical Islet Laboratory and Clinical Islet Transplant Program, University of Alberta, Edmonton, Alberta, Canada
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics and Pancreatic Islet Biology and Diabetes Consortium, Imperial College London, London, U.K
| | - Alejandra Tomas
- Section of Cell Biology and Functional Genomics and Pancreatic Islet Biology and Diabetes Consortium, Imperial College London, London, U.K.
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9
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Jones B, Bloom SR, Buenaventura T, Tomas A, Rutter GA. Control of insulin secretion by GLP-1. Peptides 2018; 100:75-84. [PMID: 29412835 DOI: 10.1016/j.peptides.2017.12.013] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Revised: 12/13/2017] [Accepted: 12/14/2017] [Indexed: 12/12/2022]
Abstract
Stimulation of insulin secretion by glucagon-like peptide-1 (GLP-1) and other gut-derived peptides is central to the incretin response to ingesting nutriments. Analogues of GLP-1, and inhibitors of its breakdown, have found widespread clinical use for the treatment of type 2 diabetes (T2D) and obesity. The release of these peptides underlies the improvements in glycaemic control and disease remission after bariatric surgery. Given therapeutically, GLP-1 analogues can lead to side effects including nausea, which limit dosage. Greater understanding of the interactions between the GLP-1 receptor (GLP-1R) and both the endogenous and artificial ligands therefore holds promise to provide more efficacious compounds. Here, we discuss recent findings concerning the signalling and trafficking of the GLP-1R in pancreatic beta cells. Leveraging "bias" at the receptor towards cAMP generation versus the recruitment of β-arrestins and extracellular signal-regulated kinases (ERK1/2) activation may allow the development of new analogues with significantly improved clinical efficacy. We describe how, unexpectedly, relatively low-affinity agonists, which prompt less receptor internalisation than the parent compound, provoke greater insulin secretion and consequent improvements in glycaemia.
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Affiliation(s)
- Ben Jones
- Section of Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK
| | - Stephen R Bloom
- Section of Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK
| | - Teresa Buenaventura
- Section of Cell Biology and Functional Genomics & Imperial Consortium for Islet Biology and Diabetes, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK
| | - Alejandra Tomas
- Section of Cell Biology and Functional Genomics & Imperial Consortium for Islet Biology and Diabetes, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics & Imperial Consortium for Islet Biology and Diabetes, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
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10
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Heucken N, Ivanov R. The retromer, sorting nexins and the plant endomembrane protein trafficking. J Cell Sci 2018; 131:jcs.203695. [PMID: 29061884 DOI: 10.1242/jcs.203695] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Protein sorting in the endomembrane system is responsible for the coordination of cellular functions. Plant intracellular trafficking has its own unique features, which include specific regulatory aspects of endosomal sorting and recycling of cargo proteins, mediated by the retromer complex. Recent work has led to significant progress in understanding the role of Arabidopsis retromer subunits in recycling vacuolar sorting receptors and plasma membrane proteins. As a consequence, members of the sorting nexin (SNX) protein family and their interaction partners have emerged as critical protein trafficking regulators, in particular with regard to adaptation to environmental change, such as temperature fluctuations and nutrient deficiency. In this Review, we discuss the known and proposed functions of the comparatively small Arabidopsis SNX protein family. We review the available information on the role of the three Bin-Amphiphysin-Rvs (BAR)-domain-containing Arabidopsis thaliana (At)SNX proteins and discuss their function in the context of their potential participation in the plant retromer complex. We also summarize the role of AtSNX1-interacting proteins in different aspects of SNX-dependent protein trafficking and comment on the potential function of three novel, as yet unexplored, Arabidopsis SNX proteins.
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Affiliation(s)
- Nicole Heucken
- Institute of Botany, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Rumen Ivanov
- Institute of Botany, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
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11
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Extracellular vesicle budding is inhibited by redundant regulators of TAT-5 flippase localization and phospholipid asymmetry. Proc Natl Acad Sci U S A 2018; 115:E1127-E1136. [PMID: 29367422 PMCID: PMC5819400 DOI: 10.1073/pnas.1714085115] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cells release extracellular vesicles (EVs) that mediate intercellular communication and repair damaged membranes. Despite the pleiotropic functions of EVs in vitro, their in vivo function is debated, largely because it is unclear how to induce or inhibit their formation. In particular, the mechanisms of EV release by plasma membrane budding or ectocytosis are poorly understood. We previously showed that TAT-5 phospholipid flippase activity maintains the asymmetric localization of the lipid phosphatidylethanolamine (PE) in the plasma membrane and inhibits EV budding by ectocytosis in Caenorhabditis elegans However, no proteins that inhibit ectocytosis upstream of TAT-5 were known. Here, we identify TAT-5 regulators associated with retrograde endosomal recycling: PI3Kinase VPS-34, Beclin1 homolog BEC-1, DnaJ protein RME-8, and the uncharacterized Dopey homolog PAD-1. PI3Kinase, RME-8, and semiredundant sorting nexins are required for the plasma membrane localization of TAT-5, which is important to maintain PE asymmetry and inhibit EV release. PAD-1 does not directly regulate TAT-5 localization, but is required for the lipid flipping activity of TAT-5. PAD-1 also has roles in endosomal trafficking with the GEF-like protein MON-2, which regulates PE asymmetry and EV release redundantly with sorting nexins independent of the core retromer. Thus, in addition to uncovering redundant intracellular trafficking pathways, our study identifies additional proteins that regulate EV release. This work pinpoints TAT-5 and PE as key regulators of plasma membrane budding, further supporting the model that PE externalization drives ectocytosis.
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Nishimura A, Sunggip C, Oda S, Numaga-Tomita T, Tsuda M, Nishida M. Purinergic P2Y receptors: Molecular diversity and implications for treatment of cardiovascular diseases. Pharmacol Ther 2017. [DOI: 10.1016/j.pharmthera.2017.06.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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13
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Abubakar YS, Zheng W, Olsson S, Zhou J. Updated Insight into the Physiological and Pathological Roles of the Retromer Complex. Int J Mol Sci 2017; 18:ijms18081601. [PMID: 28757549 PMCID: PMC5577995 DOI: 10.3390/ijms18081601] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 07/20/2017] [Accepted: 07/21/2017] [Indexed: 12/13/2022] Open
Abstract
Retromer complexes mediate protein trafficking from the endosomes to the trans-Golgi network (TGN) or through direct recycling to the plasma membrane. In yeast, they consist of a conserved trimer of the cargo selective complex (CSC), Vps26-Vps35-Vps29 and a dimer of sorting nexins (SNXs), Vps5-Vps17. In mammals, the CSC interacts with different kinds of SNX proteins in addition to the mammalian homologues of Vps5 and Vps17, which further diversifies retromer functions. The retromer complex plays important roles in many cellular processes including restriction of invading pathogens. In this review, we summarize some recent developments in our understanding of the physiological and pathological functions of the retromer complex.
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Affiliation(s)
- Yakubu Saddeeq Abubakar
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Wenhui Zheng
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Stefan Olsson
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Jie Zhou
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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14
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Saimani U, Kim K. Traffic from the endosome towards trans-Golgi network. Eur J Cell Biol 2017; 96:198-205. [PMID: 28256269 DOI: 10.1016/j.ejcb.2017.02.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/24/2017] [Accepted: 02/16/2017] [Indexed: 11/16/2022] Open
Abstract
Retrograde passage of a transport carrier entails cargo sorting at the endosome, generation of a cargo-laden carrier and its movement along cytoskeletal tracks towards trans-Golgi network (TGN), tethering at the TGN, and fusion with the Golgi membrane. Significant advances have been made in understanding this traffic system, revealing molecular requirements in each step and the functional connection between them as well as biomedical implication of the dysregulation of those important traffic factors. This review focuses on describing up-to-date action mechanisms for retrograde transport from the endosomal system to the TGN.
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Affiliation(s)
- Uma Saimani
- Department of Biology, Missouri State University, 901 S National, Springfield, MO 65807, United States
| | - Kyoungtae Kim
- Department of Biology, Missouri State University, 901 S National, Springfield, MO 65807, United States.
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Bhosle VK, Rivera JC, Chemtob S. New insights into mechanisms of nuclear translocation of G-protein coupled receptors. Small GTPases 2017; 10:254-263. [PMID: 28125336 DOI: 10.1080/21541248.2017.1282402] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The G-protein coupled receptor (GPCR) signaling was long believed to involve activation of receptor exclusively at the cell surface, followed by its binding to heterotrimeric G-proteins and arrestins to trigger various intracellular signaling cascades, and termination of signaling by internalization of the receptor. It is now accepted that many GPCRs continue to signal after internalization in the endosomes. Since the breakthrough discoveries of nuclear binding sites for their ligands in 1980s, several GPCRs have been detected at cell nuclei. But mechanisms of nuclear localization of GPCRs, many of whom contain putative nuclear localization signals, remain poorly understood to date. Nevertheless, it is known that subcellular trafficking of GPCRs is regulated by members of Ras superfamily of small GTPases, most notably by Rab and Arf GTPases. In this commentary, we highlight several recent studies which suggest novel roles of small GTPases, importins and sorting nexin proteins in the nuclear translocation of GPCRs via vesicular transport pathways. Taken together with increasing evidence for in vivo functionality of the nuclear GPCRs, better understanding of their trafficking will provide valuable clues in cell biology.
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Affiliation(s)
- Vikrant K Bhosle
- a Department of Pharmacology and Therapeutics , McGill University , Montréal , Québec , Canada.,b CHU Sainte-Justine Hospital Research Centre , University of Montréal , Montréal , Québec , Canada.,c Maisonneuve-Rosemont Hospital Research Centre , University of Montréal , Montréal , Québec , Canada.,e Cell Biology Program , Peter Gilgan Centre for Research and Learning , Toronto , Ontario , Canada
| | - José Carlos Rivera
- b CHU Sainte-Justine Hospital Research Centre , University of Montréal , Montréal , Québec , Canada.,c Maisonneuve-Rosemont Hospital Research Centre , University of Montréal , Montréal , Québec , Canada
| | - Sylvain Chemtob
- a Department of Pharmacology and Therapeutics , McGill University , Montréal , Québec , Canada.,b CHU Sainte-Justine Hospital Research Centre , University of Montréal , Montréal , Québec , Canada.,c Maisonneuve-Rosemont Hospital Research Centre , University of Montréal , Montréal , Québec , Canada.,d Departments of Pediatrics, Ophthalmology and Pharmacology , University of Montréal , Montréal , Québec , Canada
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16
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Caspase-mediated proteolysis of the sorting nexin 2 disrupts retromer assembly and potentiates Met/hepatocyte growth factor receptor signaling. Cell Death Discov 2017; 3:16100. [PMID: 28179995 PMCID: PMC5253419 DOI: 10.1038/cddiscovery.2016.100] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 11/23/2016] [Indexed: 12/14/2022] Open
Abstract
The unfolding of apoptosis involves the cleavage of hundreds of proteins by the caspase family of cysteinyl peptidases. Among those substrates are proteins involved in intracellular vesicle trafficking with a net outcome of shutting down the crucial processes governing protein transport to organelles and to the plasma membrane. However, because of the intertwining of receptor trafficking and signaling, cleavage of specific proteins may lead to unintended consequences. Here we show that in apoptosis, sorting nexin 1 and 2 (SNX1 and SNX2), two proteins involved in endosomal sorting, are cleaved by initiator caspases and also by executioner caspase-6 in the case of SNX2. Moreover, SNX1 is cleaved at multiple sites, including following glutamate residues. Cleavage of SNX2 results in a loss of association with the endosome-to-trans-Golgi network transport protein Vps35 and in a delocalization from endosomes of its associated partner Vps26. We also demonstrate that SNX2 depletion causes an increase in hepatocyte growth factor receptor tyrosine phosphorylation and Erk1/2 signaling in cells. Finally, we show that SNX2 mRNA and protein levels are decreased in colorectal carcinoma and that lower SNX2 gene expression correlates with an increase in cancer patient mortality. Our study reveals the importance to characterize the cleavage fragments produced by caspases of specific death substrates given their potential implication in the mechanism of regulation of physiological (signaling/trafficking) pathways or in the dysfunction leading to pathogenesis.
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Dores MR, Grimsey NJ, Mendez F, Trejo J. ALIX Regulates the Ubiquitin-Independent Lysosomal Sorting of the P2Y1 Purinergic Receptor via a YPX3L Motif. PLoS One 2016; 11:e0157587. [PMID: 27301021 PMCID: PMC4907476 DOI: 10.1371/journal.pone.0157587] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 06/01/2016] [Indexed: 12/22/2022] Open
Abstract
Endocytic sorting and lysosomal degradation are integral to the regulation of G protein-coupled receptor (GPCR) function. Upon ligand binding, classical GPCRs are activated, internalized and recycled or sorted to lysosomes for degradation, a process that requires receptor ubiquitination. However, recent studies have demonstrated that numerous GPCRs are sorted to lysosomes independent of receptor ubiquitination. Here, we describe an ubiquitin-independent lysosomal sorting pathway for the purinergic GPCR P2Y1. After activation, P2Y1 sorts to lysosomes for degradation independent of direct ubiquitination that is mediated by a YPX3L motif within the second intracellular loop that serves as a binding site for the adaptor protein ALIX. Depletion of ALIX or site-directed mutation of the YPX3L motif inhibits P2Y1 sorting into the lumen of multivesicular endosomes/lysosomes and degradation. These findings confirm the function of YPX3L motifs as lysosomal targeting sequences for GPCRs and demonstrate that ALIX mediates the ubiquitin-independent degradation of certain GPCRs.
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Affiliation(s)
- Michael R. Dores
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA 92093, United States of America
- Department of Biology, Hofstra University, Hempstead, NY 11549, United States of America
| | - Neil J. Grimsey
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA 92093, United States of America
| | - Francisco Mendez
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA 92093, United States of America
| | - JoAnn Trejo
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA 92093, United States of America
- * E-mail:
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18
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Li C, Shah SZA, Zhao D, Yang L. Role of the Retromer Complex in Neurodegenerative Diseases. Front Aging Neurosci 2016; 8:42. [PMID: 26973516 PMCID: PMC4772447 DOI: 10.3389/fnagi.2016.00042] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/15/2016] [Indexed: 11/13/2022] Open
Abstract
The retromer complex is a protein complex that plays a central role in endosomal trafficking. Retromer dysfunction has been linked to a growing number of neurological disorders. The process of intracellular trafficking and recycling is crucial for maintaining normal intracellular homeostasis, which is partly achieved through the activity of the retromer complex. The retromer complex plays a primary role in sorting endosomal cargo back to the cell surface for reuse, to the trans-Golgi network (TGN), or alternatively to specialized endomembrane compartments, in which the cargo is not subjected to lysosomal-mediated degradation. In most cases, the retromer acts as a core that interacts with associated proteins, including sorting nexin family member 27 (SNX27), members of the vacuolar protein sorting 10 (VPS10) receptor family, the major endosomal actin polymerization-promoting complex known as Wiskott-Aldrich syndrome protein and scar homolog (WASH), and other proteins. Some of the molecules carried by the retromer complex are risk factors for neurodegenerative diseases. Defects such as haplo-insufficiency or mutations in one or several units of the retromer complex lead to various pathologies. Here, we summarize the molecular architecture of the retromer complex and the roles of this system in intracellular trafficking related the pathogenesis of neurodegenerative diseases.
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Affiliation(s)
- Chaosi Li
- National Animal Transmissible Spongiform Encephalopathy Laboratory, Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University Beijing, China
| | - Syed Zahid Ali Shah
- National Animal Transmissible Spongiform Encephalopathy Laboratory, Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University Beijing, China
| | - Deming Zhao
- National Animal Transmissible Spongiform Encephalopathy Laboratory, Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University Beijing, China
| | - Lifeng Yang
- National Animal Transmissible Spongiform Encephalopathy Laboratory, Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University Beijing, China
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19
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Li C, Ma W, Yin S, Liang X, Shu X, Pei D, Egan TM, Huang J, Pan A, Li Z. Sorting Nexin 11 Regulates Lysosomal Degradation of Plasma Membrane TRPV3. Traffic 2016; 17:500-14. [DOI: 10.1111/tra.12379] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 01/21/2016] [Accepted: 01/21/2016] [Indexed: 12/15/2022]
Affiliation(s)
- Caiyue Li
- Key Laboratory of Regenerative Biology, Chinese Academy of Sciences and Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine; Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences; Guangzhou China
| | - Wenbo Ma
- Key Laboratory of Regenerative Biology, Chinese Academy of Sciences and Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine; Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences; Guangzhou China
| | - Shikui Yin
- Key Laboratory of Regenerative Biology, Chinese Academy of Sciences and Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine; Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences; Guangzhou China
| | - Xin Liang
- Key Laboratory of Regenerative Biology, Chinese Academy of Sciences and Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine; Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences; Guangzhou China
| | - Xiaodong Shu
- Key Laboratory of Regenerative Biology, Chinese Academy of Sciences and Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine; Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences; Guangzhou China
| | - Duanqing Pei
- Key Laboratory of Regenerative Biology, Chinese Academy of Sciences and Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine; Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences; Guangzhou China
| | - Terrance M. Egan
- Pharmacological and Physiological Science, School of Medicine; Saint Louis University; St. Louis MO USA
| | - Jufang Huang
- Department of Anatomy and Neurobiology, Xiangya School of Medicine; Central South University; Changsha China
| | - Aihua Pan
- Department of Anatomy and Neurobiology, Xiangya School of Medicine; Central South University; Changsha China
| | - Zhiyuan Li
- Key Laboratory of Regenerative Biology, Chinese Academy of Sciences and Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine; Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences; Guangzhou China
- Department of Anatomy and Neurobiology, Xiangya School of Medicine; Central South University; Changsha China
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20
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Golkowski M, Shimizu-Albergine M, Suh HW, Beavo JA, Ong SE. Studying mechanisms of cAMP and cyclic nucleotide phosphodiesterase signaling in Leydig cell function with phosphoproteomics. Cell Signal 2015; 28:764-78. [PMID: 26643407 DOI: 10.1016/j.cellsig.2015.11.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 11/26/2015] [Indexed: 12/21/2022]
Abstract
Many cellular processes are modulated by cyclic AMP and nucleotide phosphodiesterases (PDEs) regulate this second messenger by catalyzing its breakdown. The major unique function of testicular Leydig cells is to produce testosterone in response to luteinizing hormone (LH). Treatment of Leydig cells with PDE inhibitors increases cAMP levels and the activity of its downstream effector, cAMP-dependent protein kinase (PKA), leading to a series of kinase-dependent signaling and transcription events that ultimately increase testosterone release. We have recently shown that PDE4B and PDE4C as well as PDE8A and PDE8B are expressed in rodent Leydig cells and that combined inhibition of PDE4 and PDE8 leads to dramatically increased steroid biosynthesis. Here we investigated the effect of PDE4 and PDE8 inhibition on the molecular mechanisms of cAMP actions in a mouse MA10 Leydig cell line model with SILAC mass spectrometry-based phosphoproteomics. We treated MA10 cells either with PDE4 family specific inhibitor (Rolipram) and PDE8 family specific inhibitor (PF-04957325) alone or in combination and quantified the resulting phosphorylation changes at five different time points between 0 and 180min. We identified 28,336 phosphosites from 4837 proteins and observed significant regulation of 749 sites in response to PDE4 and PDE8 inhibitor treatment. Of these, 132 phosphosites were consensus PKA sites. Our data strongly suggest that PDE4 and PDE8 inhibitors synergistically regulate phosphorylation of proteins required for many different cellular processes, including cell cycle progression, lipid and glucose metabolism, transcription, endocytosis and vesicle transport. Our data suggests that cAMP, PDE4 and PDE8 coordinate steroidogenesis by acting on not one rate-limiting step but rather multiple pathways. Moreover, the pools of cAMP controlled by these PDEs also coordinate many other metabolic processes that may be regulated to assure timely and sufficient testosterone secretion in response to LH.
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Affiliation(s)
- Martin Golkowski
- Department of Pharmacology, School of Medicine, University of Washington, USA
| | | | - Hyong Won Suh
- Department of Pharmacology, School of Medicine, University of Washington, USA
| | - Joseph A Beavo
- Department of Pharmacology, School of Medicine, University of Washington, USA.
| | - Shao-En Ong
- Department of Pharmacology, School of Medicine, University of Washington, USA.
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21
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The Proteome of the Isolated Chlamydia trachomatis Containing Vacuole Reveals a Complex Trafficking Platform Enriched for Retromer Components. PLoS Pathog 2015; 11:e1004883. [PMID: 26042774 PMCID: PMC4456400 DOI: 10.1371/journal.ppat.1004883] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 04/14/2015] [Indexed: 12/22/2022] Open
Abstract
Chlamydia trachomatis is an important human pathogen that replicates inside the infected host cell in a unique vacuole, the inclusion. The formation of this intracellular bacterial niche is essential for productive Chlamydia infections. Despite its importance for Chlamydia biology, a holistic view on the protein composition of the inclusion, including its membrane, is currently missing. Here we describe the host cell-derived proteome of isolated C. trachomatis inclusions by quantitative proteomics. Computational analysis indicated that the inclusion is a complex intracellular trafficking platform that interacts with host cells’ antero- and retrograde trafficking pathways. Furthermore, the inclusion is highly enriched for sorting nexins of the SNX-BAR retromer, a complex essential for retrograde trafficking. Functional studies showed that in particular, SNX5 controls the C. trachomatis infection and that retrograde trafficking is essential for infectious progeny formation. In summary, these findings suggest that C. trachomatis hijacks retrograde pathways for effective infection. The important human pathogen Chlamydia trachomatis causes 100 million new infections each year world-wide. It replicates inside the infected host cell in a unique vacuole, the inclusion. Currently, the nature, and specifically the protein composition of the inclusion, is poorly defined. Here, we described the host cell-derived inclusion proteome by quantitative proteomics using a newly established method to purify inclusions from infected epithelial cells. We showed that the inclusion is a complex intracellular trafficking platform that is well embedded into the organellar network and interacts with host cells’ antero- and retrograde trafficking pathways. Particularly, SNX1, 2, 5 and 6, components of the retromer, are recruited to the inclusion and seem to control the infection. We found also that retrograde trafficking is essential for Chlamydia progeny formation. Our study provides new insights into how the obligate intracellular bacterium C. trachomatis interacts with the eukaryotic host cell and subverts host cell functions for productive infection.
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22
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Filipeanu CM, Pullikuth AK, Guidry JJ. Molecular determinants of the human α2C-adrenergic receptor temperature-sensitive intracellular traffic. Mol Pharmacol 2015; 87:792-802. [PMID: 25680754 PMCID: PMC4407737 DOI: 10.1124/mol.114.096198] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 02/12/2015] [Indexed: 01/22/2023] Open
Abstract
The human α2C-adrenergic receptor (α2C-AR) is localized intracellularly at physiologic temperature. Decreasing the environmental temperature strongly stimulates the receptor transport to the cell surface. In contrast, rat and mouse α2C-AR plasma membrane levels are less sensitive to decrease in temperature, whereas the opossum α2C-AR cell surface levels are not changed in these conditions. Structural analysis demonstrated that human α2C-AR has a high number of arginine residues in the third intracellular loop and in the C-terminus, organized as putative RXR motifs. Although these motifs do not affect the receptor subcellular localization at 37°C, deletion of the arginine clusters significantly enhanced receptor plasma membrane levels at reduced temperature. We found that this exaggerated transport of the human receptor is mediated by two functional arginine clusters, one in the third intracellular loop and one in the C-terminus. This effect is mediated by interactions with COPI vesicles, but not by 14-3-3 proteins. In rat α2C-AR, the arginine cluster from the third intracellular loop is shifted to the left due to three missing residues. Reinsertion of these residues in the rat α2C-AR restored the same temperature sensitivity as in the human receptor. Proteomic and coimmunoprecipitation experiments identified pontin as a molecule having stronger interactions with human α2C-AR compared with rat α2C-AR. Inhibition of pontin activity enhanced human receptor plasma membrane levels and signaling at 37°C. Our results demonstrate that human α2C-AR has a unique temperature-sensitive traffic pattern within the G protein-coupled receptor class due to interactions with different molecular chaperones, mediated in part by strict spatial localization of specific arginine residues.
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Affiliation(s)
- Catalin M Filipeanu
- Department of Pharmacology, College of Medicine, Howard University, Washington, DC (C.M.F.); Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana (A.K.P., J.J.G.); Department of Cancer Biology, Wake Forest University School of Medicine, Winston Salem, North Carolina (A.K.P.); and Louisiana State University Health Sciences Center Proteomics Core Facility, New Orleans, Louisiana (J.J.G.)
| | - Ashok K Pullikuth
- Department of Pharmacology, College of Medicine, Howard University, Washington, DC (C.M.F.); Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana (A.K.P., J.J.G.); Department of Cancer Biology, Wake Forest University School of Medicine, Winston Salem, North Carolina (A.K.P.); and Louisiana State University Health Sciences Center Proteomics Core Facility, New Orleans, Louisiana (J.J.G.)
| | - Jessie J Guidry
- Department of Pharmacology, College of Medicine, Howard University, Washington, DC (C.M.F.); Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana (A.K.P., J.J.G.); Department of Cancer Biology, Wake Forest University School of Medicine, Winston Salem, North Carolina (A.K.P.); and Louisiana State University Health Sciences Center Proteomics Core Facility, New Orleans, Louisiana (J.J.G.)
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23
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Zhou K, Sumigray KD, Lechler T. The Arp2/3 complex has essential roles in vesicle trafficking and transcytosis in the mammalian small intestine. Mol Biol Cell 2015; 26:1995-2004. [PMID: 25833710 PMCID: PMC4472011 DOI: 10.1091/mbc.e14-10-1481] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 03/23/2015] [Indexed: 12/23/2022] Open
Abstract
The Arp2/3 complex has essential functions in the intestinal epithelium. Loss of ArpC3 results in vesicle-trafficking defects that prevent transcytosis of immunoglobulins and efficient absorption of lipids but does not affect levels of cortical F-actin. The Arp2/3 complex is the only known nucleator of branched F-actin filaments. Work in cultured cells has established a wide array of functions for this complex in controlling cell migration, shape, and adhesion. However, loss of Arp2/3 complex function in tissues has yielded cell type–specific phenotypes. Here we report essential functions of the Arp2/3 complex in the intestinal epithelium. The Arp2/3 complex was dispensable for intestinal development, generation of cortical F-actin, and cell polarity. However, it played essential roles in vesicle trafficking. We found that in the absence of ArpC3, enterocytes had defects in the organization of the endolysosomal system. These defects were physiologically relevant, as transcytosis of IgG was disrupted, lipid absorption was perturbed, and neonatal mice died within days of birth. These data highlight the important roles of the Arp2/3 complex in vesicle trafficking in enterocytes and suggest that defects in cytoplasmic F-actin assembly by the Arp2/3 complex, rather than cortical pools, underlie many of the phenotypes seen in the mutant small intestine.
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Affiliation(s)
- Kang Zhou
- Department of Dermatology and Department of Cell Biology, Duke University Medical Center, Durham, NC 27710
| | - Kaelyn D Sumigray
- Department of Dermatology and Department of Cell Biology, Duke University Medical Center, Durham, NC 27710
| | - Terry Lechler
- Department of Dermatology and Department of Cell Biology, Duke University Medical Center, Durham, NC 27710
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24
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Harbour ME, Seaman MNJ. Evolutionary variations of VPS29, and their implications for the heteropentameric model of retromer. Commun Integr Biol 2014. [DOI: 10.4161/cib.16855] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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25
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Terenzio M, Golding M, Russell MRG, Wicher KB, Rosewell I, Spencer-Dene B, Ish-Horowicz D, Schiavo G. Bicaudal-D1 regulates the intracellular sorting and signalling of neurotrophin receptors. EMBO J 2014; 33:1582-98. [PMID: 24920579 PMCID: PMC4198053 DOI: 10.15252/embj.201387579] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 03/14/2014] [Accepted: 04/23/2014] [Indexed: 12/31/2022] Open
Abstract
We have identified a new function for the dynein adaptor Bicaudal D homolog 1 (BICD1) by screening a siRNA library for genes affecting the dynamics of neurotrophin receptor-containing endosomes in motor neurons (MNs). Depleting BICD1 increased the intracellular accumulation of brain-derived neurotrophic factor (BDNF)-activated TrkB and p75 neurotrophin receptor (p75(NTR)) by disrupting the endosomal sorting, reducing lysosomal degradation and increasing the co-localisation of these neurotrophin receptors with retromer-associated sorting nexin 1. The resulting re-routing of active receptors increased their recycling to the plasma membrane and altered the repertoire of signalling-competent TrkB isoforms and p75(NTR) available for ligand binding on the neuronal surface. This resulted in attenuated, but more sustained, AKT activation in response to BDNF stimulation. These data, together with our observation that Bicd1 expression is restricted to the developing nervous system when neurotrophin receptor expression peaks, indicate that BICD1 regulates neurotrophin signalling by modulating the endosomal sorting of internalised ligand-activated receptors.
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Affiliation(s)
- Marco Terenzio
- Molecular NeuroPathobiology Laboratory, Cancer Research UK London Research Institute, London, UK
| | - Matthew Golding
- Molecular NeuroPathobiology Laboratory, Cancer Research UK London Research Institute, London, UK
| | - Matthew R G Russell
- Electron Microscopy Laboratory, Cancer Research UK London Research Institute, London, UK
| | - Krzysztof B Wicher
- Developmental Genetics Laboratory, Cancer Research UK London Research Institute, London, UK
| | - Ian Rosewell
- Transgenic Services laboratory, Cancer Research UK London Research Institute, London, UK
| | - Bradley Spencer-Dene
- Experimental Histopathology Laboratory, Cancer Research UK London Research Institute, London, UK
| | - David Ish-Horowicz
- Developmental Genetics Laboratory, Cancer Research UK London Research Institute, London, UK
| | - Giampietro Schiavo
- Molecular NeuroPathobiology Laboratory, Cancer Research UK London Research Institute, London, UK Sobell Department of Motor Neuroscience & Movement Disorders, UCL-Institute of Neurology, University College London, London, UK
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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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O'Brien CE, Wyss-Coray T. Sorting through the roles of beclin 1 in microglia and neurodegeneration. J Neuroimmune Pharmacol 2014; 9:285-92. [PMID: 24385262 DOI: 10.1007/s11481-013-9519-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 12/13/2013] [Indexed: 02/03/2023]
Abstract
Beclin 1 has a well-established role in regulating autophagy, a cellular degradation pathway. Although the yeast ortholog of beclin 1 (Atg6/Vps30) was discovered to also regulate vacuolar protein sorting nearly 30 years ago, the varied functions of beclin 1 in mammalian cells are only beginning to be sorted out. We recently described a role for beclin 1 in regulating recycling of phagocytic receptors in microglia, a function analogous to that of its yeast ortholog. Microglia lacking beclin 1 have a reduced phagocytic capacity, which impairs clearance of amyloid β (Aβ) in a mouse model of Alzheimer's Disease (AD). Here we summarize these findings and discuss the implications for beclin 1-regulated receptor recycling in neurodegenerative disease.
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Affiliation(s)
- Caitlin E O'Brien
- Cell and Molecular Biology Program, Stanford University, Stanford, CA, 94305, USA
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Fukaya M, Fukushima D, Hara Y, Sakagami H. EFA6A, a guanine nucleotide exchange factor for Arf6, interacts with sorting nexin-1 and regulates neurite outgrowth. J Neurochem 2013; 129:21-36. [PMID: 24261326 DOI: 10.1111/jnc.12524] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 10/09/2013] [Accepted: 11/04/2013] [Indexed: 01/11/2023]
Abstract
The membrane trafficking and actin cytoskeleton remodeling mediated by ADP ribosylation factor 6 (Arf6) are functionally linked to various neuronal processes including neurite formation and maintenance, neurotransmitter release, and receptor internalization. EFA6A is an Arf6-specific guanine nucleotide exchange factor that is abundantly expressed in the brain. In this study, we identified sorting nexin-1 (SNX1), a retromer component that is implicated in endosomal sorting and trafficking, as a novel interacting partner for EFA6A by yeast two-hybrid screening. The interaction was mediated by the C-terminal region of EFA6A and a BAR domain of SNX1, and further confirmed by pull-down assay and immunoprecipitation from mouse brain lysates. In situ hybridization analysis demonstrated the widespread expression of SNX1 in the mouse brain, which overlapped with the expression of EFA6A in the forebrain. Immunofluorescent analysis revealed the partial colocalization of EFA6A and SNX1 in the dendritic fields of the hippocampus. Immunoelectron microscopic analysis revealed the overlapping subcellular localization of EFA6A and SNX1 at the post-synaptic density and endosomes in dendritic spines. In Neuro-2a neuroblastoma cells, expression of either EFA6A or SNX1 induced neurite outgrowth, which was further enhanced by co-expression of EFA6A and SNX1. The present findings suggest a novel mechanism by which EFA6A regulates Arf6-mediated neurite formation through the interaction with SNX1.
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Affiliation(s)
- Masahiro Fukaya
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
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29
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Zelazny E, Santambrogio M, Gaude T. Retromer association with membranes: plants have their own rules! PLANT SIGNALING & BEHAVIOR 2013; 8:25312. [PMID: 23803747 PMCID: PMC4002585 DOI: 10.4161/psb.25312] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The retromer is an endosome-localized complex involved in protein trafficking. To better understand its function and regulation in plants, we recently investigated how Arabidopsis retromer subunits assemble and are targeted to endosomal membranes and highlighted original features compared with mammals. We characterized Arabidopsis vps26 null mutant and showed that it displays severe developmental defaults similar to those observed in vps29 mutant. Here, we go further by describing new phenotypic defects associated with loss of VPS26 function, such as inhibition of lateral root initiation. Recently, we showed that VPS35 subunit plays a crucial role in the recruitment of the plant retromer to endosomes, probably through an interaction with the Rab7 homolog RABG3f. In this work, we now show that contrary to mammals, Arabidopsis Rab5 homologs do not seem to be necessary for the recruitment of the core retromer to endosomal membranes, which highlights a new specificity of the plant retromer.
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Affiliation(s)
- Enric Zelazny
- Centre National de la Recherche Scientifique; Lyon, France
- Institut National de la Recherche Agronomique; Lyon, France
- Ecole Normale Supérieure de Lyon; Lyon, France
- Université Lyon 1; Villeurbanne, France
- Unité Mixte de Service Biosciences Gerland; Lyon, France
| | - Martina Santambrogio
- Centre National de la Recherche Scientifique; Lyon, France
- Institut National de la Recherche Agronomique; Lyon, France
- Ecole Normale Supérieure de Lyon; Lyon, France
- Université Lyon 1; Villeurbanne, France
- Unité Mixte de Service Biosciences Gerland; Lyon, France
| | - Thierry Gaude
- Centre National de la Recherche Scientifique; Lyon, France
- Institut National de la Recherche Agronomique; Lyon, France
- Ecole Normale Supérieure de Lyon; Lyon, France
- Université Lyon 1; Villeurbanne, France
- Unité Mixte de Service Biosciences Gerland; Lyon, France
- Correspondence to: Thierry Gaude,
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Abstract
Platelets are critical for haemostasis, however inappropriate activation can lead to the development of arterial thrombosis, which can result in heart attack and stroke. ADP is a key platelet agonist that exerts its actions via stimulation of two surface GPCRs (G-protein-coupled receptors), P2Y(1) and P2Y(12). Similar to most GPCRs, P2Y receptor activity is tightly regulated by a number of complex mechanisms including receptor desensitization, internalization and recycling. In the present article, we review the molecular mechanisms that underlie P2Y(1) and P2Y(12) receptor regulation, with particular emphasis on the structural motifs within the P2Y(12) receptor, which are required to maintain regulatory protein interaction. The implications of these findings for platelet responsiveness are also discussed.
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31
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Allison R, Lumb JH, Fassier C, Connell JW, Ten Martin D, Seaman MNJ, Hazan J, Reid E. An ESCRT-spastin interaction promotes fission of recycling tubules from the endosome. ACTA ACUST UNITED AC 2013; 202:527-43. [PMID: 23897888 PMCID: PMC3734076 DOI: 10.1083/jcb.201211045] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Inclusion of IST1 into the ESCRT complex allows recruitment of the microtubule-severing protein spastin to promote fission of recycling tubules from the endosome. Mechanisms coordinating endosomal degradation and recycling are poorly understood, as are the cellular roles of microtubule (MT) severing. We show that cells lacking the MT-severing protein spastin had increased tubulation of and defective receptor sorting through endosomal tubular recycling compartments. Spastin required the ability to sever MTs and to interact with ESCRT-III (a complex controlling cargo degradation) proteins to regulate endosomal tubulation. Cells lacking IST1 (increased sodium tolerance 1), an endosomal sorting complex required for transport (ESCRT) component to which spastin binds, also had increased endosomal tubulation. Our results suggest that inclusion of IST1 into the ESCRT complex allows recruitment of spastin to promote fission of recycling tubules from the endosome. Thus, we reveal a novel cellular role for MT severing and identify a mechanism by which endosomal recycling can be coordinated with the degradative machinery. Spastin is mutated in the axonopathy hereditary spastic paraplegia. Zebrafish spinal motor axons depleted of spastin or IST1 also had abnormal endosomal tubulation, so we propose this phenotype is important for axonal degeneration.
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Affiliation(s)
- Rachel Allison
- Department of Medical Genetics, University of Cambridge, Cambridge CB2 0XY, England, UK
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32
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Cunningham MR, Nisar SP, Cooke AE, Emery ED, Mundell SJ. Differential endosomal sorting of a novel P2Y12 purinoreceptor mutant. Traffic 2013; 14:585-98. [PMID: 23387322 DOI: 10.1111/tra.12054] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 01/30/2013] [Accepted: 02/06/2013] [Indexed: 12/11/2022]
Abstract
P2Y12 receptor internalization and recycling play an essential role in ADP-induced platelet activation. Recently, we identified a patient with a mild bleeding disorder carrying a heterozygous mutation of P2Y12 (P341A) whose P2Y12 receptor recycling was significantly compromised. Using human cell line models, we identified key proteins regulating wild-type (WT) P2Y12 recycling and investigated P2Y12 -P341A receptor traffic. Treatment with ADP resulted in delayed Rab5-dependent internalization of P341A when compared with WT P2Y12 . While WT P2Y12 rapidly recycled back to the membrane via Rab4 and Rab11 recycling pathways, limited P341A recycling was observed, which relied upon Rab11 activity. Although minimal receptor degradation was evident, P341A was localized in Rab7-positive endosomes with considerable agonist-dependent accumulation in the trans-Golgi network (TGN). Rab7 activity is known to facilitate recruitment of retromer complex proteins to endosomes to transport cargo to the TGN. Here, we identified that P341A colocalized with Vps26; depletion of which blocked limited recycling and promoted receptor degradation. This study has identified key points of divergence in the endocytic traffic of P341A versus WT-P2Y12 . Given that these pathways are retained in human platelets, this research helps define the molecular mechanisms regulating P2Y12 receptor traffic and explain the compromised receptor function in the platelets of the P2Y12 -P341A-expressing patient.
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Affiliation(s)
- Margaret R Cunningham
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK
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33
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Villar VAM, Jones JE, Armando I, Asico LD, Escano CS, Lee H, Wang X, Yang Y, Pascua-Crusan AM, Palmes-Saloma CP, Felder RA, Jose PA. Sorting nexin 1 loss results in D5 dopamine receptor dysfunction in human renal proximal tubule cells and hypertension in mice. J Biol Chem 2012; 288:152-63. [PMID: 23152498 DOI: 10.1074/jbc.m112.428458] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The peripheral dopaminergic system plays a crucial role in blood pressure regulation through its actions on renal hemodynamics and epithelial ion transport. The dopamine D5 receptor (D(5)R) interacts with sorting nexin 1 (SNX1), a protein involved in receptor retrieval from the trans-Golgi network. In this report, we elucidated the spatial, temporal, and functional significance of this interaction in human renal proximal tubule cells and HEK293 cells stably expressing human D(5)R and in mice. Silencing of SNX1 expression via RNAi resulted in the failure of D(5)R to internalize and bind GTP, blunting of the agonist-induced increase in cAMP production and decrease in sodium transport, and up-regulation of angiotensin II receptor expression, of which expression was previously shown to be negatively regulated by D(5)R. Moreover, siRNA-mediated depletion of renal SNX1 in C57BL/6J and BALB/cJ mice resulted in increased blood pressure and blunted natriuretic response to agonist in salt-loaded BALB/cJ mice. These data demonstrate a crucial role for SNX1 in D(5)R trafficking and that SNX1 depletion results in D(5)R dysfunction and thus may represent a novel mechanism for the pathogenesis of essential hypertension.
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Affiliation(s)
- Van Anthony M Villar
- Center for Molecular Physiology Research, Children's Research Institute, Children's National Medical Center, Washington DC 20010, USA.
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Abstract
The retromer complex is a vital element of the endosomal protein sorting machinery that is conserved across all eukaryotes. Retromer is most closely associated with the endosome-to-Golgi retrieval pathway and is necessary to maintain an active pool of hydrolase receptors in the trans-Golgi network. Recent progress in studies of retromer have identified new retromer-interacting proteins, including the WASH complex and cargo such as the Wntless/MIG-14 protein, which now extends the role of retromer beyond the endosome-to-Golgi pathway and has revealed that retromer is required for aspects of endosome-to-plasma membrane sorting and regulation of signalling events. The interactions between the retromer complex and other macromolecular protein complexes now show how endosomal protein sorting is coordinated with actin assembly and movement along microtubules, and place retromer squarely at the centre of a complex set of protein machinery that governs endosomal protein sorting. Dysregulation of retromer-mediated endosomal protein sorting leads to various pathologies, including neurodegenerative diseases such as Alzheimer disease and spastic paraplegia and the mechanisms underlying these pathologies are starting to be understood. In this Commentary, I will highlight recent advances in the understanding of retromer-mediated endosomal protein sorting and discuss how retromer contributes to a diverse set of physiological processes.
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Oikonomou G, Perens EA, Lu Y, Shaham S. Some, but not all, retromer components promote morphogenesis of C. elegans sensory compartments. Dev Biol 2012; 362:42-9. [PMID: 22138055 PMCID: PMC3254776 DOI: 10.1016/j.ydbio.2011.11.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 10/31/2011] [Accepted: 11/12/2011] [Indexed: 12/26/2022]
Abstract
The endings of sensory receptor cells often lie within specialized compartments formed by glial cells. The main sensory organ of Caenorhabditis elegans, the amphid, provides a powerful setting for studying glial compartment morphogenesis. Our previous studies showed that amphid compartment size is controlled by opposing activities of the Nemo-like kinase LIT-1, which promotes compartment expansion, and the Patched-related protein DAF-6, which restricts compartment growth. From a genetic screen for mutations able to suppress the bloated sensory compartments of daf-6 mutants, we identified an allele of the sorting nexin gene snx-1. SNX-1 protein is a component of the retromer, a protein complex that facilitates recycling of transmembrane proteins from the endosome to the Golgi network. We find that snx-1 functions cell autonomously within glia to promote sensory compartment growth, and that SNX-1 protein is enriched near the surface of the sensory compartment. snx-1 interacts genetically with lit-1 and another regulator of compartment size, the Dispatched-related gene che-14. Mutations in snx-3 and vps-29, also retromer genes, can suppress daf-6 defects. Surprisingly, however, remaining retromer components seem not to be involved. Our results suggest that a novel assembly of retromer components is important for determining sensory compartment dimensions.
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Affiliation(s)
- Grigorios Oikonomou
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
| | - Elliot A. Perens
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
| | - Yun Lu
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
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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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37
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Lu N, Zhou Z. Membrane trafficking and phagosome maturation during the clearance of apoptotic cells. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 293:269-309. [PMID: 22251564 PMCID: PMC3551535 DOI: 10.1016/b978-0-12-394304-0.00013-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Apoptosis is a cellular suicide process that quietly and efficiently eliminates unwanted or damaged cells. In metazoans, cells that undergo apoptosis are swiftly internalized by phagocytes and subsequently degraded inside phagosomes through phagosome maturation, a process that involves the fusion between phagosomes and multiple kinds of intracellular organelles and the gradual acidification of phagosomal lumen. In recent years, rapid progress has been made, in particular, through studies conducted in the model organism, the nematode Caenorhabditis elegans, in understanding the membrane trafficking events and molecular mechanisms that govern the degradation of apoptotic cells through phagosome maturation. These studies revealed the novel and essential functions of a large number of proteins, including the large GTPase dynamin, multiple Rab small GTPases and their regulatory proteins, the lipid second messenger PtdIns(3)P and its effectors, and unexpectedly, the phagosomal receptors for apoptotic cells, in promoting phagosome maturation. Further, novel signaling pathways essential for phagosome maturation have been delineated. Here, we discuss these exciting new findings, which have significantly deepened and broadened our understanding of the mechanisms that regulate the interaction between intracellular organelles and phagosomes.
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Affiliation(s)
- Nan Lu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
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38
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Guo Y, Jose PA. C-terminal di-leucine motif of dopamine D₁ receptor plays an important role in its plasma membrane trafficking. PLoS One 2011; 6:e29204. [PMID: 22206002 PMCID: PMC3242775 DOI: 10.1371/journal.pone.0029204] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 11/22/2011] [Indexed: 12/12/2022] Open
Abstract
The dopamine D1 receptor (D1R), a G protein-coupled receptor, plays a critical role in regulating blood pressure through its actions on renal hemodynamics and epithelial ion transport, which are highly linked to its intracellular trafficking. In this study, we generated a series of C-terminal mutants of D1R that were tagged with or without enhanced yellow fluorescent protein, and analyzed the consequences of these mutants on the plasma membrane trafficking of D1R and cyclic AMP response to D1R stimulation. D1R with mutations within the endocytic recycling signal (amino acid residues 360–382) continued to be functional, albeit decreased relative to wild-type D1R. Mutation of the palmitoylation site (347C>S) of D1R did not impair its trafficking to the plasma membrane, but abolished its ability to increase cyclic AMP accumulation. In contrast, replacement of di-leucines (344–345L>A) by alanines resulted in the retention of D1R in the early endosome, decreased its glycosylation, and prevented its targeting to the plasma membrane. Our studies suggest that di-L motif at the C-terminus of D1R is critical for the glycosylation and cell surface targeting of D1R.
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Affiliation(s)
- Yan Guo
- Center for Molecular Physiology Research, Children's National Medical Center, Washington, D.C, United States of America.
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39
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van Weering JRT, Verkade P, Cullen PJ. SNX-BAR-mediated endosome tubulation is co-ordinated with endosome maturation. Traffic 2011; 13:94-107. [PMID: 21973056 DOI: 10.1111/j.1600-0854.2011.01297.x] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Endosomal sorting is essential for cell homeostasis. Proteins targeted for degradation are retained in the maturing endosome vacuole while others are recycled to the cell surface or sorted to the biosynthetic pathway via tubular transport carriers. Sorting nexin (SNX) proteins containing a BAR (for Bin-Amphiphysin-Rvs) domain are key regulators of phosphoinositide-mediated, tubular-based endosomal sorting, but how such sorting is co-ordinated with endosomal maturation is not known. Here, using well-defined Rab GTPases as endosomal compartment markers, we have analyzed the localization of SNX1 [endosome-to-trans-Golgi network (TGN) transport as part of the SNX-BAR-retromer complex], SNX4 (cargo-recycling from endosomes to the plasma membrane) and SNX8 (endosomes-to-TGN trafficking in a retromer-independent manner). We show that these SNX-BARs are primarily localized to early endosomes, but display the highest frequency of tubule formation at the moment of early-to-late endosome transition: the Rab5-to-Rab7 switch. Perturbing this switch shifts SNX-BAR tubulation to early endosomes, resulting in SNX1-decorated tubules that lack retromer components VPS26 and VPS35, suggesting that both early and late endosomal characteristics of the endosome are important for SNX-BAR-retromer-tubule formation. We also establish that SNX4, but not SNX1 and SNX8, is associated with the Rab11-recycling endosomes and that a high frequency of SNX4-mediated tubule formation is observed as endosomes undergo Rab4-to-Rab11 transition. Our study therefore provides evidence for fine-tuning between the processes of endosomal maturation and the formation of endosomal tubules. As tubulation is required for SNX1-, SNX4- and SNX8-mediated sorting, these data reveal a previously unrecognized co-ordination between maturation and tubular-based sorting.
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Affiliation(s)
- Jan R T van Weering
- Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, University Walk, Bristol, UK
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40
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Harbour ME, Seaman MNJ. Evolutionary variations of VPS29, and their implications for the heteropentameric model of retromer. Commun Integr Biol 2011; 4:619-22. [PMID: 22046480 DOI: 10.4161/cib.4.5.16855] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 06/09/2011] [Indexed: 11/19/2022] Open
Abstract
The retromer complex is conserved across all eukaryotic species and functions in physiologically important sorting processes at the endosomal membrane. A key component of retromer is the VPS29 protein that, although structurally similar to phospho-diesterases, has been convincingly shown in the recent study by Swarbrick et al. (PLoS One 6:e20420, 2011) to be a rigid scaffold that interacts with various proteins that function with retromer in endosomal protein sorting. A widely held view, based on initial observations in Saccharomyces cerevisiae, is that retromer functions as a stable heteropentamer. This is, however, contrary to experimental data presented in Swarbrick et al. (and in other studies) that indicate that retromer in higher eukaryotes is a looser association of two subcomplexes that respectively mediate cargo-selection and membrane tubulation. Here we present an analysis of evolutionary variation of the VPS29 protein and discuss why the retromer complex as first characterized in S. cerevisiae is not representative of retromer in other eukaryotic taxa.
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Affiliation(s)
- Michael E Harbour
- University of Cambridge; Cambridge Institue for Medical Research; Addenbrookes Hospital; Cambridge, UK
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41
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Lu N, Shen Q, Mahoney TR, Liu X, Zhou Z. Three sorting nexins drive the degradation of apoptotic cells in response to PtdIns(3)P signaling. Mol Biol Cell 2011; 22:354-74. [PMID: 21148288 PMCID: PMC3031466 DOI: 10.1091/mbc.e10-09-0756] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
LST-4/SNX9, SNX-1, and SNX-6 together drive the degradation of apoptotic cells, as PtdIns(3)P effectors, during Caenorhabditis elegans development. By inducing regional membrane curvature and maintaining RAB-7 GTPase on phagosomes, these three sorting nexins stimulate the fusion of endocytic organelles with phagosomes. Apoptotic cells are swiftly engulfed by phagocytes and degraded inside phagosomes. Phagosome maturation requires phosphatidylinositol 3-phosphate [PtdIns(3)P], yet how PtdIns(3)P triggers phagosome maturation remains largely unknown. Through a genome-wide PtdIns(3)P effector screen in the nematode Caenorhabditis elegans, we identified LST-4/SNX9, SNX-1, and SNX-6, three BAR domain-containing sorting nexins, that act in two parallel pathways to drive PtdIns(3)P-mediated degradation of apoptotic cells. We found that these proteins were enriched on phagosomal surfaces through association with PtdIns(3)P and through specific protein–protein interaction, and they promoted the fusion of early endosomes and lysosomes to phagosomes, events essential for phagosome maturation. Specifically, LST-4 interacts with DYN-1 (dynamin), an essential phagosome maturation initiator, to strengthen DYN-1’s association to phagosomal surfaces, and facilitates the maintenance of the RAB-7 GTPase on phagosomal surfaces. Furthermore, both LST-4 and SNX-1 promote the extension of phagosomal tubules to facilitate the docking and fusion of intracellular vesicles. Our findings identify the critical and differential functions of two groups of sorting nexins in phagosome maturation and reveal a signaling cascade initiated by phagocytic receptor CED-1, mediated by PtdIns(3)P, and executed through these sorting nexins to degrade apoptotic cells.
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Affiliation(s)
- Nan Lu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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42
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Abstract
The endosomal network is an organized array of intracellular, membranous compartments that function as sorting sites for endosomal and biosynthetic cargo. The fate of endocytic cargo is reliant upon interactions with a number of molecularly distinct sorting complexes, which tightly control the relationship between sorting of their respective cargo and the physical process of membrane re-scuplturing required for the formation of transport carries. One such complex, retromer, mediates retrograde transport from endosomes to the trans-Golgi network (TGN). Disregulation of retromer has been implicated in a host of disease states including late-onset Alzheimer's. Rather than give a broad overview of retromer biology, here we aim to outline the recent advances in understanding this complex, focussing on the involvement of both clathrin and the cytoskeleton in retromer function.
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Affiliation(s)
- Ian J McGough
- Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK
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Park SJ, Huh JW, Kim YH, Kim JS, Song BS, Lee SR, Kim SU, Kim HS, Imakawa K, Chang KT. Quantitative analysis of retromer complex-related genes during embryo development in the mouse. Mol Cells 2011; 31:431-6. [PMID: 21359680 PMCID: PMC3887610 DOI: 10.1007/s10059-011-0272-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 01/27/2011] [Accepted: 02/09/2011] [Indexed: 10/18/2022] Open
Abstract
The retromer complex is a heteropentameric protein unit associated with retrograde transport of cargo proteins from endosomes to the trans-Golgi network. Functional silencing study of the Vps26a gene indicated the important role of the retromer complex during early developmental stages in the mouse. However, individual expression patterns and quantitative analysis of individual members of the retromer complex during the early developmental stages has not been investigated. In this study, we conducted quantitative expression analysis of six retromer complex genes (Vps26a, Vps26b, Vps29, Vps35, Snx1, and Snx2) and one related receptor gene (Ci-mpr) during the eleven embryonic stages with normal MEF (mouse embryonic fibroblast) and Vps26a(-/-) MEF cells. Remarkably, except for Vps26a (maternal expression pattern), all tested genes showed maternal-zygotic expression patterns. And five genes (Vps26b, Vps29, Vps35, Snx2, and Ci-mpr) showed a pattern of decreased expression in Vps26a(-/-) MEF cells by comparative analysis between normal MEF and Vps26a(-/-) MEF cells. However, the Snx1 gene showed a pattern of increased expression in Vps26a(-/-) MEF cells. From our results, we could assume that retromer complex-related genes have important roles during oocyte development. However, in the preimplantation stage, they did not have significant roles.
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Affiliation(s)
- Sang-Je Park
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology, Ochang 363-883, Korea
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Korea
- These authors contributed equally to this work
| | - Jae-Won Huh
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology, Ochang 363-883, Korea
- These authors contributed equally to this work
| | - Young-Hyun Kim
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology, Ochang 363-883, Korea
- Department of Functional Genomics, University of Science and Technology, Daejeon 305-333, Korea
- These authors contributed equally to this work
| | - Ji-Su Kim
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology, Ochang 363-883, Korea
- These authors contributed equally to this work
| | - Bong-Seok Song
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology, Ochang 363-883, Korea
| | - Sang-Rae Lee
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology, Ochang 363-883, Korea
| | - Sun-Uk Kim
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology, Ochang 363-883, Korea
| | - Heui-Soo Kim
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Korea
| | - Kazuhiko Imakawa
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Kyu-Tae Chang
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology, Ochang 363-883, Korea
- Department of Functional Genomics, University of Science and Technology, Daejeon 305-333, Korea
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Prosser DC, Tran D, Schooley A, Wendland B, Ngsee JK. A novel, retromer-independent role for sorting nexins 1 and 2 in RhoG-dependent membrane remodeling. Traffic 2011; 11:1347-62. [PMID: 20604901 DOI: 10.1111/j.1600-0854.2010.01100.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The sorting nexins SNX1 and SNX2 are members of the retromer complex involved in protein sorting within the endocytic pathway. While retromer-dependent functions of SNX1 and SNX2 have been well documented, potential retromer-independent roles remain unclear. Here, we show that SNX1 and SNX2 interact with the Rac1 and RhoG guanine nucleotide exchange factor Kalirin-7. Simultaneous overexpression of SNX1 or SNX2 and Kalirin-7 in epithelial cells causes partial redistribution of both SNX isoforms to the plasma membrane, and results in RhoG-dependent lamellipodia formation that requires functional Phox homology (PX) and Bin/Amphiphysin/Rvs (BAR) domains of SNX, but is Rac1- and retromer-independent. Conversely, depletion of endogenous SNX1 or SNX2 inhibits Kalirin-7-mediated lamellipodia formation. Finally, we demonstrate that SNX1 and SNX2 interact directly with inactive RhoG, suggesting a novel role for these SNX proteins in recruiting an inactive Rho GTPase to its exchange factor.
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Affiliation(s)
- Derek C Prosser
- Department of Cellular and Molecular Medicine, Ottawa Hospital Research Institute, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada
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Harbour ME, Breusegem SYA, Antrobus R, Freeman C, Reid E, Seaman MNJ. The cargo-selective retromer complex is a recruiting hub for protein complexes that regulate endosomal tubule dynamics. J Cell Sci 2010; 123:3703-17. [PMID: 20923837 DOI: 10.1242/jcs.071472] [Citation(s) in RCA: 198] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The retromer complex is required for the efficient endosome-to-Golgi retrieval of the CIMPR, sortilin, SORL1, wntless and other physiologically important membrane proteins. Retromer comprises two protein complexes that act together in endosome-to-Golgi retrieval; the cargo-selective complex is a trimer of VPS35, VPS29 and VPS26 that sorts cargo into tubules for retrieval to the Golgi. Tubules are produced by the oligomerization of sorting nexin dimers. Here, we report the identification of five endosomally-localised proteins that modulate tubule formation and are recruited to the membrane via interactions with the cargo-selective retromer complex. One of the retromer-interacting proteins, strumpellin, is mutated in hereditary spastic paraplegia, a progressive length-dependent axonopathy. Here, we show that strumpellin regulates endosomal tubules as part of a protein complex with three other proteins that include WASH1, an actin-nucleating promoting factor. Therefore, in addition to a direct role in endosome-to-Golgi retrieval, the cargo-selective retromer complex also acts as a platform for recruiting physiologically important proteins to endosomal membranes that regulate membrane tubule dynamics.
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Affiliation(s)
- Michael E Harbour
- Department of Clinical Biochemistry, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrookes Hospital, Cambridge CB2 0XY, UK
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