1
|
Anglès F, Gupta V, Wang C, Balch WE. COPII cage assembly factor Sec13 integrates information flow regulating endomembrane function in response to human variation. Sci Rep 2024; 14:10160. [PMID: 38698045 PMCID: PMC11065896 DOI: 10.1038/s41598-024-60687-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 04/26/2024] [Indexed: 05/05/2024] Open
Abstract
How information flow is coordinated for managing transit of 1/3 of the genome through endomembrane pathways by the coat complex II (COPII) system in response to human variation remains an enigma. By examining the interactome of the COPII cage-assembly component Sec13, we show that it is simultaneously associated with multiple protein complexes that facilitate different features of a continuous program of chromatin organization, transcription, translation, trafficking, and degradation steps that are differentially sensitive to Sec13 levels. For the trafficking step, and unlike other COPII components, reduction of Sec13 expression decreased the ubiquitination and degradation of wild-type (WT) and F508del variant cargo protein cystic fibrosis transmembrane conductance regulator (CFTR) leading to a striking increase in fold stability suggesting that the events differentiating export from degradation are critically dependent on COPII cage assembly at the ER Golgi intermediate compartment (ERGIC) associated recycling and degradation step linked to COPI exchange. Given Sec13's multiple roles in protein complex assemblies that change in response to its expression, we suggest that Sec13 serves as an unanticipated master regulator coordinating information flow from the genome to the proteome to facilitate spatial covariant features initiating and maintaining design and function of membrane architecture in response to human variation.
Collapse
Affiliation(s)
- Frédéric Anglès
- Department of Molecular Medicine, The Scripps Research Institute, 10550 North Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Vijay Gupta
- Department of Molecular Medicine, The Scripps Research Institute, 10550 North Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Chao Wang
- Department of Molecular Medicine, The Scripps Research Institute, 10550 North Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - William E Balch
- Department of Molecular Medicine, The Scripps Research Institute, 10550 North Torrey Pines Rd, La Jolla, CA, 92037, USA.
| |
Collapse
|
2
|
Amaral MD. Using the genome to correct the ion transport defect in cystic fibrosis. J Physiol 2022; 601:1573-1582. [PMID: 36068724 DOI: 10.1113/jp282308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 08/31/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Human genome information can help finding drugs for human diseases. 'Omics' allow unbiased identification of novel drug targets. High-throughput (HT) approaches provide a global view on disease mechanisms. As a monogenic disease CF has led the way in multiple 'Omic' studies. 'Multi-omics' integration will generate maximal biological significance. ABSTRACT Today Biomedicine faces one of its greatest challenges, i.e. treating diseases through their causative dysfunctional processes and not just their symptoms. However, we still miss a global view of mechanisms and pathways involved in pathophysiology of most diseases. In fact, disease mechanisms and pathways can be achieved by holistic studies provided by 'Omic' approaches. Cystic Fibrosis (CF), caused by mutations in the CF transmembrane conductance regulator (CFTR) gene which encodes an anion channel, is paradigmatic for monogenic disorders, namely channelopathies. A high number of 'omics studies' have focussed on CF, namely several cell-based high-throughput (HT) approaches were developed and applied towards a global mechanistic characterization of CF pathophysiology and the identification of novel and 'unbiased' drug targets. Notwithstanding, it is likely that, through the integration of all these 'layers' of large datasets into comprehensive disease maps that biological significance can be extracted so that the enormous potential of these approaches to identifying dysfunctional mechanisms and novel drugs may become a reality. Abstract figure legend Schematic overview of the 3 main approaches to discovery of new drugs/drug targets. This article is protected by copyright. All rights reserved.
Collapse
Affiliation(s)
- Margarida D Amaral
- BioISI - Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande-C8 bdg, Lisboa, 1749-016, Portugal
| |
Collapse
|
3
|
Wang C, Anglès F, Balch WE. Triangulating variation in the population to define mechanisms for precision management of genetic disease. Structure 2022; 30:1190-1207.e5. [PMID: 35714602 PMCID: PMC9357173 DOI: 10.1016/j.str.2022.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 04/18/2022] [Accepted: 05/17/2022] [Indexed: 10/18/2022]
Abstract
To understand mechanistically how the protein fold is shaped by therapeutics to inform precision management of disease, we developed variation-capture (VarC) mapping. VarC triangulates sparse sequence variation information found in the population using Gaussian process regression (GPR)-based machine learning to define the combined pairwise-residue interactions contributing to dynamic protein function in the individual in response to therapeutics. Using VarC mapping, we now reveal the pairwise-residue covariant relationships across the entire protein fold of cystic fibrosis (CF) transmembrane conductance regulator (CFTR) to define the molecular mechanisms of clinically approved CF chemical modulators. We discover an energetically destabilized covariant core containing a di-acidic YKDAD endoplasmic reticulum (ER) exit code that is only weakly corrected by current therapeutics. Our results illustrate that VarC provides a generalizable tool to triangulate information from genetic variation in the population to mechanistically discover therapeutic strategies that guide precision management of the individual.
Collapse
Affiliation(s)
- Chao Wang
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Frédéric Anglès
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - William E Balch
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA.
| |
Collapse
|
4
|
Anglès F, Wang C, Balch WE. Spatial covariance analysis reveals the residue-by-residue thermodynamic contribution of variation to the CFTR fold. Commun Biol 2022; 5:356. [PMID: 35418593 PMCID: PMC9008016 DOI: 10.1038/s42003-022-03302-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 03/21/2022] [Indexed: 12/21/2022] Open
Abstract
Although the impact of genome variation on the thermodynamic properties of function on the protein fold has been studied in vitro, it remains a challenge to assign these relationships across the entire polypeptide sequence in vivo. Using the Gaussian process regression based principle of Spatial CoVariance, we globally assign on a residue-by-residue basis the biological thermodynamic properties that contribute to the functional fold of CFTR in the cell. We demonstrate the existence of a thermodynamically sensitive region of the CFTR fold involving the interface between NBD1 and ICL4 that contributes to its export from endoplasmic reticulum. At the cell surface a new set of residues contribute uniquely to the management of channel function. These results support a general ‘quality assurance’ view of global protein fold management as an SCV principle describing the differential pre- and post-ER residue interactions contributing to compartmentalization of the energetics of the protein fold for function. Our results set the stage for future analyses of the quality systems managing protein sequence-to-function-to-structure broadly encompassing genome design leading to protein function in complex cellular relationships responsible for diversity and fitness in biology in response to the environment. Spatial covariance analysis shows how each residue in the critical fold region of chloride channel CFTR, defective in cystic fibrosis patients, contributes to CFTR’s export from the endoplasmic reticulum and function in the cell.
Collapse
Affiliation(s)
- Frédéric Anglès
- Scripps Research, Department of Molecular Medicine, 10550 North Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Chao Wang
- Scripps Research, Department of Molecular Medicine, 10550 North Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - William E Balch
- Scripps Research, Department of Molecular Medicine, 10550 North Torrey Pines Rd, La Jolla, CA, 92037, USA.
| |
Collapse
|
5
|
Xu X, Wei Z, Wu G. Specific motifs mediate post-synaptic and surface transport of G protein-coupled receptors. iScience 2022; 25:103643. [PMID: 35024582 PMCID: PMC8728401 DOI: 10.1016/j.isci.2021.103643] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/19/2021] [Accepted: 12/14/2021] [Indexed: 12/23/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are key regulators of synaptic functions. However, their targeted trafficking to synapses after synthesis is poorly understood. Here, we demonstrate that multiple motifs mediate α2B-adrenergic receptor transport to the dendritic and post-synaptic compartments in primary hippocampal neurons, with a single leucine residue on the first intracellular loop being specifically involved in synaptic targeting. The N-terminally located tyrosine-serine motif operates differently in neuronal and non-neuronal cells. We further show that the highly conserved dileucine (LL) motif in the C-terminus is required for the dendritic and post-synaptic traffic of all GPCRs studied. The LL motif also directs the export from the endoplasmic reticulum of a chimeric GPCR and confers its transport ability to vesicular stomatitis virus glycoprotein in cell lines. Collectively, these data reveal the intrinsic structural determinants for the synaptic targeting of nascent GPCRs and their cell-type-specific trafficking along the biosynthetic pathways.
Collapse
Affiliation(s)
- Xin Xu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Zhe Wei
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Guangyu Wu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| |
Collapse
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Wouters R, Michiels C, Sannerud R, Kleizen B, Dillen K, Vermeire W, Ayala AE, Demedts D, Schekman R, Annaert W. Assembly of γ-secretase occurs through stable dimers after exit from the endoplasmic reticulum. J Cell Biol 2021; 220:212501. [PMID: 34292306 PMCID: PMC8302450 DOI: 10.1083/jcb.201911104] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/29/2020] [Accepted: 06/07/2021] [Indexed: 01/22/2023] Open
Abstract
γ-Secretase affects many physiological processes through targeting >100 substrates; malfunctioning links γ-secretase to cancer and Alzheimer’s disease. The spatiotemporal regulation of its stoichiometric assembly remains unresolved. Fractionation, biochemical assays, and imaging support prior formation of stable dimers in the ER, which, after ER exit, assemble into full complexes. In vitro ER budding shows that none of the subunits is required for the exit of others. However, knockout of any subunit leads to the accumulation of incomplete subcomplexes in COPII vesicles. Mutating a DPE motif in presenilin 1 (PSEN1) abrogates ER exit of PSEN1 and PEN-2 but not nicastrin. We explain this by the preferential sorting of PSEN1 and nicastrin through Sec24A and Sec24C/D, respectively, arguing against full assembly before ER exit. Thus, dimeric subcomplexes aided by Sec24 paralog selectivity support a stepwise assembly of γ-secretase, controlling final levels in post-Golgi compartments.
Collapse
Affiliation(s)
- Rosanne Wouters
- Laboratory for Membrane Trafficking, Vlaams Instituut voor Biotechnologie Center for Brain and Disease Research, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Christine Michiels
- Laboratory for Membrane Trafficking, Vlaams Instituut voor Biotechnologie Center for Brain and Disease Research, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Ragna Sannerud
- Laboratory for Membrane Trafficking, Vlaams Instituut voor Biotechnologie Center for Brain and Disease Research, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Bertrand Kleizen
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Katleen Dillen
- Laboratory for Membrane Trafficking, Vlaams Instituut voor Biotechnologie Center for Brain and Disease Research, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Wendy Vermeire
- Laboratory for Membrane Trafficking, Vlaams Instituut voor Biotechnologie Center for Brain and Disease Research, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Abril Escamilla Ayala
- Vlaams Instituut voor Biotechnologie BioImaging Core, Vlaams Instituut voor Biotechnologie Center for Brain and Disease Research, Leuven, Belgium
| | - David Demedts
- Laboratory for Membrane Trafficking, Vlaams Instituut voor Biotechnologie Center for Brain and Disease Research, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Randy Schekman
- Department of Molecular and Cell Biology and Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA
| | - Wim Annaert
- Laboratory for Membrane Trafficking, Vlaams Instituut voor Biotechnologie Center for Brain and Disease Research, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| |
Collapse
|
8
|
Abstract
In 1994, a convergence of ideas and collaborative research orchestrated by Randy Schekman led to the discovery of the coat protein complex II (COPII). In this Perspective, the chain of events enabling discovery of a new vesicle coat and progress on understanding COPII budding mechanisms are considered.
Collapse
Affiliation(s)
- Charles Barlowe
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| |
Collapse
|
9
|
Zeyen L, Döring T, Stieler JT, Prange R. Hepatitis B subviral envelope particles use the COPII machinery for intracellular transport via selective exploitation of Sec24A and Sec23B. Cell Microbiol 2020; 22:e13181. [PMID: 32017353 DOI: 10.1111/cmi.13181] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 01/18/2020] [Accepted: 01/28/2020] [Indexed: 12/12/2022]
Abstract
Hepatitis B virus (HBV) is a leading cause of liver disease. Its success as a human pathogen is related to the immense production of subviral envelope particles (SVPs) contributing to viral persistence by interfering with immune functions. To explore cellular pathways involved in SVP formation and egress, we investigated host-pathogen interactions. Yeast-based proteomics revealed Sec24A, a component of the coat protein complex II (COPII), as an interaction partner of the HBV envelope S domain. To understand how HBV co-opts COPII as a proviral machinery, we studied roles of key Sec proteins in HBV-expressing liver cells. Silencing of Sar1, Sec23, and Sec24, which promote COPII assembly concomitant with cargo loading, strongly diminished endoplasmic reticulum (ER) envelope export and SVP secretion. By analysing Sec paralog specificities, we unexpectedly found that the HBV envelope is a selective interaction partner of Sec24A and Sec23B whose functions could not be substituted by their related isoforms. In support, we found that HBV replication upregulated Sec24A and Sec23B transcription. Furthermore, HBV encountered the Sec24A/Sec23B complex via an interaction that involved the N-terminal half of Sec24A and a di-arginine motif of its S domain, mirroring a novel ER export code. Accordingly, an interference with the COPII/HBV cross-talk might display a tool to effectively inhibit SVP release.
Collapse
Affiliation(s)
- Lisa Zeyen
- Department of Virology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Tatjana Döring
- Department of Virology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Jens T Stieler
- Department of Molecular and Cellular Mechanisms of Neurodegeneration, Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany
| | - Reinhild Prange
- Department of Virology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| |
Collapse
|
10
|
Wang B, Stanford KR, Kundu M. ER-to-Golgi Trafficking and Its Implication in Neurological Diseases. Cells 2020; 9:E408. [PMID: 32053905 PMCID: PMC7073182 DOI: 10.3390/cells9020408] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/27/2020] [Accepted: 02/07/2020] [Indexed: 12/21/2022] Open
Abstract
Membrane and secretory proteins are essential for almost every aspect of cellular function. These proteins are incorporated into ER-derived carriers and transported to the Golgi before being sorted for delivery to their final destination. Although ER-to-Golgi trafficking is highly conserved among eukaryotes, several layers of complexity have been added to meet the increased demands of complex cell types in metazoans. The specialized morphology of neurons and the necessity for precise spatiotemporal control over membrane and secretory protein localization and function make them particularly vulnerable to defects in trafficking. This review summarizes the general mechanisms involved in ER-to-Golgi trafficking and highlights mutations in genes affecting this process, which are associated with neurological diseases in humans.
Collapse
Affiliation(s)
- Bo Wang
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (B.W.); (K.R.S.)
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Katherine R. Stanford
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (B.W.); (K.R.S.)
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Mondira Kundu
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (B.W.); (K.R.S.)
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| |
Collapse
|
11
|
Subramanian A, Capalbo A, Iyengar NR, Rizzo R, di Campli A, Di Martino R, Lo Monte M, Beccari AR, Yerudkar A, Del Vecchio C, Glielmo L, Turacchio G, Pirozzi M, Kim SG, Henklein P, Cancino J, Parashuraman S, Diviani D, Fanelli F, Sallese M, Luini A. Auto-regulation of Secretory Flux by Sensing and Responding to the Folded Cargo Protein Load in the Endoplasmic Reticulum. Cell 2020; 176:1461-1476.e23. [PMID: 30849374 DOI: 10.1016/j.cell.2019.01.035] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 08/30/2018] [Accepted: 01/23/2019] [Indexed: 11/19/2022]
Abstract
Maintaining the optimal performance of cell processes and organelles is the task of auto-regulatory systems. Here we describe an auto-regulatory device that helps to maintain homeostasis of the endoplasmic reticulum (ER) by adjusting the secretory flux to the cargo load. The cargo-recruiting subunit of the coatomer protein II (COPII) coat, Sec24, doubles as a sensor of folded cargo and, upon cargo binding, acts as a guanine nucleotide exchange factor to activate the signaling protein Gα12 at the ER exit sites (ERESs). This step, in turn, activates a complex signaling network that activates and coordinates the ER export machinery and attenuates proteins synthesis, thus preventing large fluctuations of folded and potentially active cargo that could be harmful to the cell or the organism. We call this mechanism AREX (autoregulation of ER export) and expect that its identification will aid our understanding of human physiology and diseases that develop from secretory dysfunction.
Collapse
Affiliation(s)
- Advait Subramanian
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy.
| | - Anita Capalbo
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Namrata Ravi Iyengar
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Riccardo Rizzo
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Antonella di Campli
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy; Department of Medical, Oral and Biotechnological Sciences and CeSI-MeT, Center for Research on Ageing and Translational Medicine, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy
| | - Rosaria Di Martino
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Matteo Lo Monte
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Andrea R Beccari
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy; Dompé Farmaceutici SpA, Milan, Italy
| | - Amol Yerudkar
- Department of Engineering, Universitá degli Studi del Sannio, Benevento, Italy
| | - Carmen Del Vecchio
- Department of Engineering, Universitá degli Studi del Sannio, Benevento, Italy
| | - Luigi Glielmo
- Department of Engineering, Universitá degli Studi del Sannio, Benevento, Italy
| | - Gabriele Turacchio
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Marinella Pirozzi
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Sang Geon Kim
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, South Korea
| | - Petra Henklein
- Institut fur Biochemie, Charite Universitätsmedizin, Berlin, Germany
| | - Jorge Cancino
- Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Lota 2465, Santiago 7510157, Chile
| | | | - Dario Diviani
- Université de Lausanne, Département de Pharmacologie et Toxicologie, Rue du Bugnon 27, 1011 Lausanne, Switzerland
| | - Francesca Fanelli
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Michele Sallese
- Department of Medical, Oral and Biotechnological Sciences and CeSI-MeT, Center for Research on Ageing and Translational Medicine, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy
| | - Alberto Luini
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy.
| |
Collapse
|
12
|
Zhang M, Wu G. Mechanisms of the anterograde trafficking of GPCRs: Regulation of AT1R transport by interacting proteins and motifs. Traffic 2018; 20:110-120. [PMID: 30426616 DOI: 10.1111/tra.12624] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 10/29/2018] [Accepted: 11/08/2018] [Indexed: 12/11/2022]
Abstract
Anterograde cell surface transport of nascent G protein-coupled receptors (GPCRs) en route from the endoplasmic reticulum (ER) through the Golgi apparatus represents a crucial checkpoint to control the amount of the receptors at the functional destination and the strength of receptor activation-elicited cellular responses. However, as compared with extensively studied internalization and recycling processes, the molecular mechanisms of cell surface trafficking of GPCRs are relatively less defined. Here, we will review the current advances in understanding the ER-Golgi-cell surface transport of GPCRs and use angiotensin II type 1 receptor as a representative GPCR to discuss emerging roles of receptor-interacting proteins and specific motifs embedded within the receptors in controlling the forward traffic of GPCRs along the biosynthetic pathway.
Collapse
Affiliation(s)
- Maoxiang Zhang
- Guangzhou University of Chinese Medicine, Guangzhou, China.,Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Guangyu Wu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia
| |
Collapse
|
13
|
Padmanabhan S, Biswal MR, Manjithaya R, Prakash MK. Exploring the context of diacidic motif DE as a signal for unconventional protein secretion in eukaryotic proteins. Wellcome Open Res 2018; 3:148. [PMID: 30607372 PMCID: PMC6305234 DOI: 10.12688/wellcomeopenres.14914.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2018] [Indexed: 12/18/2022] Open
Abstract
Unconventional protein secretion (UPS) is an important phenomenon with fundamental implications to cargo export. How eukaryotic proteins transported by UPS are recognized without a conventional signal peptide has been an open question. It was recently observed that a diacidic amino acid motif (ASP-GLU or DE) is necessary for the secretion of superoxide dismutase 1 (SOD1) from yeast under nutrient starvation. Taking cue from this discovery, we explore the hypothesis of whether the diacidic motif DE, which can occur fairly ubiquitously, along with its context, can be a generic signal for unconventional secretion of proteins. Four different contexts were evaluated: a physical context encompassing the structural order and charge signature in the neighbourhood of DE, two signalling contexts reflecting the presence of either a phosphorylatable amino acid ('X' in XDE, DXE, DEX) or an LC3 interacting region (LIR) which can trigger autophagy and a co-evolutionary constraint relative to other amino acids in the protein interpreted by examining sequences across different species. Among the 100 proteins we curated from different physiological or pathological conditions, we observe a pattern in the unconventional secretion of heat shock proteins in the cancer secretome, where DE in an ordered structural region has higher odds of being a UPS signal.
Collapse
Affiliation(s)
- Sreedevi Padmanabhan
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre For Advanced Scientific Research, Bangalore, Karnataka, 560064, India
| | - Malay Ranjan Biswal
- Computational Biophysics Group, Theoretical Sciences Unit, Jawaharlal Nehru Centre For Advanced Scientific Research, Bangalore, Karnataka, 560064, India
| | - Ravi Manjithaya
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre For Advanced Scientific Research, Bangalore, Karnataka, 560064, India
| | - Meher K Prakash
- Computational Biophysics Group, Theoretical Sciences Unit, Jawaharlal Nehru Centre For Advanced Scientific Research, Bangalore, Karnataka, 560064, India
| |
Collapse
|
14
|
Abstract
The flow of cargo vesicles along the secretory pathway requires concerted action among various regulators. The COPII complex, assembled by the activated SAR1 GTPases on the surface of the endoplasmic reticulum, orchestrates protein interactions to package cargos and generate transport vesicles en route to the Golgi. The dynamic nature of COPII, however, hinders analysis with conventional biochemical assays. Here we apply proximity-dependent biotinylation labeling to capture the dynamics of COPII transport in cells. When SAR1B was fused with a promiscuous biotin ligase, BirA*, the fusion protein SAR1B-BirA* biotinylates and thus enables the capture of COPII machinery and cargos in a GTP-dependent manner. Biochemical and pulse-chase imaging experiments demonstrate that the COPII coat undergoes a dynamic cycle of engagement-disengagement with the transmembrane cargo receptor LMAN1/ERGIC53. LMAN1 undergoes a process of concentrative sorting by the COPII coat, via a dimeric sorting code generated by oligomerization of the cargo receptor. Similar oligomerization events have been observed with other COPII sorting signals, suggesting that dimeric/multimeric sorting codes may serve as a general mechanism to generate selectivity of cargo sorting.
Collapse
|
15
|
Ma W, Goldberg E, Goldberg J. ER retention is imposed by COPII protein sorting and attenuated by 4-phenylbutyrate. eLife 2017; 6. [PMID: 28594326 PMCID: PMC5464768 DOI: 10.7554/elife.26624] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 04/18/2017] [Indexed: 01/07/2023] Open
Abstract
Native cargo proteins exit the endoplasmic reticulum (ER) in COPII-coated vesicles, whereas resident and misfolded proteins are substantially excluded from vesicles by a retention mechanism that remains unresolved. We probed the ER retention process using the proteostasis regulator 4-phenylbutyrate (4-PBA), which we show targets COPII protein to reduce the stringency of retention. 4-PBA competes with p24 proteins to bind COPII. When p24 protein uptake is blocked, COPII vesicles package resident proteins and an ER-trapped mutant LDL receptor. We further show that 4-PBA triggers the secretion of a KDEL-tagged luminal resident, implying that a compromised retention mechanism causes saturation of the KDEL retrieval system. The results indicate that stringent ER retention requires the COPII coat machinery to actively sort biosynthetic cargo from diffusible misfolded and resident ER proteins. DOI:http://dx.doi.org/10.7554/eLife.26624.001
Collapse
Affiliation(s)
- Wenfu Ma
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Elena Goldberg
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Jonathan Goldberg
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States.,Howard Hughes Medical Institute, New York, United States
| |
Collapse
|
16
|
Dual-targeting of Arabidopsis DMP1 isoforms to the tonoplast and the plasma membrane. PLoS One 2017; 12:e0174062. [PMID: 28384172 PMCID: PMC5383025 DOI: 10.1371/journal.pone.0174062] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 03/02/2017] [Indexed: 12/26/2022] Open
Abstract
The reports of dual-targeted proteins in plants have steadily increased over the past years. The vast majority of these proteins are soluble proteins distributed between compartments of the non-secretory pathway, predominantly chloroplasts and mitochondria. In contrast, dual-targeted transmembrane proteins, especially of the secretory pathway, are rare and the mechanisms leading to their differential targeting remain largely unknown. Here, we report dual-targeting of the Arabidopsis DUF679 Membrane Protein 1 (DMP1) to the tonoplast (TP) and the plasma membrane (PM). In Arabidopsis and tobacco two equally abundant DMP1 isoforms are synthesized by alternative translation initiation: a full length protein, DMP1.1, and a truncated one, DMP1.2, which lacks the N-terminal 19 amino acids including a TP-targeting dileucine motif. Accumulation of DMP1.1 and DMP1.2 in the TP and the PM, respectively, is Brefeldin A-sensitive, indicating transit via the Golgi. However, DMP1.2 interacts with DMP1.1, leading to extensive rerouting of DMP1.2 to the TP and “eclipsed” localization of DMP1.2 in the PM where it is barely visible by confocal laser scanning microscopy but clearly detectable by membrane fractionation. It is demonstrated that eGFP fusion to either DMP1 terminus can cause mistargeting artifacts: C-terminal fusion to DMP1.1 or DMP1.2 results in altered ER export and N-terminal fusion to DMP1.1 causes mistargeting to the PM, presumably by masking of the TP targeting signal. These results illustrate how the interplay of alternative translation initiation, presence or absence of targeting information and rerouting due to protein-protein interaction determines the ultimate distribution of a transmembrane protein between two membranes.
Collapse
|
17
|
Abstract
Transport of newly synthesized proteins from the endoplasmic reticulum (ER) to the Golgi complex is highly selective. As a general rule, such transport is limited to soluble and membrane-associated secretory proteins that have reached properly folded and assembled conformations. To secure the efficiency, fidelity, and control of this crucial transport step, cells use a combination of mechanisms. The mechanisms are based on selective retention of proteins in the ER to prevent uptake into transport vesicles, on selective capture of proteins in COPII carrier vesicles, on inclusion of proteins in these vesicles by default as part of fluid and membrane bulk flow, and on selective retrieval of proteins from post-ER compartments by retrograde vesicle transport.
Collapse
Affiliation(s)
- Charles Barlowe
- Biochemistry Department, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755;
| | - Ari Helenius
- Institute of Biochemistry, ETH Zurich, Zurich CH-8093, Switzerland
| |
Collapse
|
18
|
Butler EC, Bradbury NA. Signal dependent ER export of lemur tyrosine kinase 2. BMC Cell Biol 2015; 16:26. [PMID: 26559041 PMCID: PMC4642647 DOI: 10.1186/s12860-015-0072-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 11/06/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The membrane anchored kinase, LMTK2, is a serine/threonine kinase predominantly localized to endosomal compartments. LMTK2 has been shown to be involved in the trafficking of the CFTR ion channel, the androgen receptor, as well as modulating neurodegeneration. As a membrane anchored protein, LMTK2 must be exported from the ER, yet the mechanisms whereby LMTK2 is sequestered within the ER for efficient export are unknown. METHODS Sequence analysis of the carboxyl tail of LMTK2 revealed a putative di-acidic ER export motif. Site-directed mutagenesis was utilized to ablate this potential motif. Subcellular fractionation, immunofluorescence microscopy, and transferrin recycling assays were used to determine the consequence of mutating LMTK2's export motif. RESULTS Mutation of the di-acidic export motif led to ER retention of LMTK2, and an increase in protein half-life and a concomitant loss of LMTK2 from its appropriate terminal destination. Loss of LMTK2 from endosomal compartments by preventing its release from the ER is linked to a reduction in transferrin recycling. CONCLUSIONS We have identified a di-acidic ER export motif within the carboxyl tail of the membrane anchored kinase LMTK2. This sequence is used by LMTK2 for its efficient export from the ER.
Collapse
Affiliation(s)
- E C Butler
- Department of Physiology and Biophysics, Chicago Medical School, 3333 Green Bay Rd, North Chicago, IL, 60064, USA.
| | - Neil A Bradbury
- Department of Physiology and Biophysics, Chicago Medical School, 3333 Green Bay Rd, North Chicago, IL, 60064, USA.
| |
Collapse
|
19
|
Spear JM, Koborssy DA, Schwartz AB, Johnson AJ, Audhya A, Fadool DA, Stagg SM. Kv1.3 contains an alternative C-terminal ER exit motif and is recruited into COPII vesicles by Sec24a. BMC BIOCHEMISTRY 2015; 16:16. [PMID: 26156069 PMCID: PMC4497498 DOI: 10.1186/s12858-015-0045-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 06/26/2015] [Indexed: 12/11/2022]
Abstract
Background Potassium channels play a fundamental role in resetting the resting membrane potential of excitable cells. Determining the intracellular trafficking and localization mechanisms of potassium channels provides a platform to fully characterize their maturation and functionality. Previous investigations have discovered residues or motifs that exist in their primary structure, which directly promote anterograde trafficking of nascent potassium channels. Recently, a non-conical di-acidic motif (E483/484) has been discovered in the C-terminus of the mammalian homologue of the Shaker voltage-gated potassium channel subfamily member 3 (Kv1.3), and was shown to disrupt the anterograde trafficking of Kv1.3. Results We have further investigated the intracellular trafficking requirements of Kv1.3 both in vivo and in vitro. First, three alternative C-terminal acidic residues, E443, E445, E447 were probed for their involvement within the early secretory pathway of Kv1.3. Single point (E443A, E445A, and E447A) and double point (E443A-E445A, E445A-E447A) mutations exhibited no significant changes in their endoplasmic reticulum (ER) retention. The triple point mutant E443A-E445A-E447A displayed a modest ER retention while deletion of the C-terminus showed dramatic ER retention. Second, we demonstrate in vivo the requirement for the Sec24a isoform to confer anterograde trafficking using a siRNA knockdown assay. Third, we show in vitro the association of recombinantly expressed Kv1.3 and Sec24a proteins. Conclusion These results expand upon previous studies aimed at deciphering the Kv1.3 secretory trafficking mechanisms and further show in vitro evidence of the association between Kv1.3 and the COPII cargo adaptor subunit isoform Sec24a. Electronic supplementary material The online version of this article (doi:10.1186/s12858-015-0045-6) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- John M Spear
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL, 32306, USA.
| | - Dolly Al Koborssy
- Program in Neuroscience, Florida State University, 1107 West Call Street, Tallahassee, FL, 32306, USA.
| | - Austin B Schwartz
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL, 32306, USA.
| | - Adam J Johnson
- Biomolecular Chemistry, University of Wisconsin-Madison, 440 Henry Mall, Madison, WI, 53706, USA.
| | - Anjon Audhya
- Biomolecular Chemistry, University of Wisconsin-Madison, 440 Henry Mall, Madison, WI, 53706, USA.
| | - Debra A Fadool
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL, 32306, USA. .,Program in Neuroscience, Florida State University, 1107 West Call Street, Tallahassee, FL, 32306, USA. .,Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL, 32306, USA.
| | - Scott M Stagg
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL, 32306, USA. .,Department of Chemistry and Biochemistry, Florida State University, 91 Chieftan Way, Tallahassee, FL, 32306, USA.
| |
Collapse
|
20
|
Wu G, Davis JE, Zhang M. Regulation of α2B-Adrenerigc Receptor Export Trafficking by Specific Motifs. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 132:227-44. [PMID: 26055061 PMCID: PMC4827153 DOI: 10.1016/bs.pmbts.2015.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Intracellular trafficking and precise targeting to specific locations of G protein-coupled receptors (GPCRs) control the physiological functions of the receptors. Compared to the extensive efforts dedicated to understanding the events involved in the endocytic and recycling pathways, the molecular mechanisms underlying the transport of the GPCR superfamily from the endoplasmic reticulum (ER) through the Golgi to the plasma membrane are relatively less well defined. Over the past years, we have used α(2B)-adrenergic receptor (α(2B)-AR) as a model to define the factors that control GPCR export trafficking. In this chapter, we will review specific motifs identified to mediate the export of nascent α(2B)-AR from the ER and the Golgi and discuss the possible underlying mechanisms. As these motifs are highly conserved among GPCRs, they may provide common mechanisms for export trafficking of these receptors.
Collapse
Affiliation(s)
- Guangyu Wu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA.
| | - Jason E Davis
- Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA
| | - Maoxiang Zhang
- Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA
| |
Collapse
|
21
|
SAP97 blocks the RXR ER retention signal of NMDA receptor subunit GluN1-3 through its SH3 domain. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:489-99. [PMID: 25499266 DOI: 10.1016/j.bbamcr.2014.11.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 11/14/2014] [Accepted: 11/30/2014] [Indexed: 11/21/2022]
Abstract
SAP97 is directly involved in exporting NMDA receptors with a specific subunit composition from the endoplasmic reticulum (ER). Characterization of the interactions between SAP97 and an NMDA receptor splice variant, GluN1-3, and of the effects on forward trafficking revealed that an ER-level interaction blocked the RXR ER-retention motif in the GluN1-3 cytoplasmic C-terminus in the context of both reporter molecules and full-length receptors. Binding of SAP97 to the PDZ-binding domain of GluN1-3 was required, but the blockade of ER-retention was mediated by the SH3-GuK domains coupled with the action of the N-terminus of SAP97. While other domains of SAP97 were involved in forward trafficking of GluN1-3 out of the ER, the SH3 domain was necessary and sufficient to block the ER retention. This is the first direct evidence for the masking of ER-retention signals by PDZ domain-containing proteins, and provides detailed underlying mechanistic requirements. Such a mechanism could be central to modulating the ER exit of receptors into local, non-conventional or conventional, secretory pathways in neurons.
Collapse
|
22
|
Myeong J, Kwak M, Hong C, Jeon JH, So I. Identification of a membrane-targeting domain of the transient receptor potential canonical (TRPC)4 channel unrelated to its formation of a tetrameric structure. J Biol Chem 2014; 289:34990-5002. [PMID: 25349210 DOI: 10.1074/jbc.m114.584649] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Canonical transient receptor potential (TRPC) channels are Ca(2+)-permeable nonselective cation channels that are activated by a wide variety of stimuli, including G protein-coupled receptors (GPCRs). The TRPC4 channel is expressed in a punctate distribution in the membrane. To identify the regulating region of the channel trafficking to the membrane, we generated deletion mutants of the TRPC4 channel. We determined that when either region that was downstream of the 20 amino acids of the N terminus or the 700-730 amino acids was deleted, the mutants were retained in the endoplasmic reticulum. By coexpression of the wild-type TRPC4 with deletion mutants, we found that the 23-29 amino acids of the N terminus regulate a membrane trafficking. Additionally, by the fluorescence resonance energy transfer (FRET) method, we found that the regions downstream of the 99 amino acid region of the N terminus and upstream of the 730 amino acid region in the C terminus produce assembly of the TRPC4 tetramers. We inferred the candidate proteins that regulate or interact with the 23-29 domain of TRPC4.
Collapse
Affiliation(s)
- Jongyun Myeong
- From the Department of Physiology, Seoul National University College of Medicine
| | - Misun Kwak
- From the Department of Physiology, Seoul National University College of Medicine
| | - Chansik Hong
- From the Department of Physiology, Seoul National University College of Medicine
| | - Ju-Hong Jeon
- From the Department of Physiology, Seoul National University College of Medicine
| | - Insuk So
- From the Department of Physiology, Seoul National University College of Medicine
| |
Collapse
|
23
|
Gutiérrez T, Simmen T. Endoplasmic reticulum chaperones and oxidoreductases: critical regulators of tumor cell survival and immunorecognition. Front Oncol 2014; 4:291. [PMID: 25386408 PMCID: PMC4209815 DOI: 10.3389/fonc.2014.00291] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 10/07/2014] [Indexed: 12/25/2022] Open
Abstract
Endoplasmic reticulum (ER) chaperones and oxidoreductases are abundant enzymes that mediate the production of fully folded secretory and transmembrane proteins. Resisting the Golgi and plasma membrane-directed “bulk flow,” ER chaperones and oxidoreductases enter retrograde trafficking whenever they are pulled outside of the ER by their substrates. Solid tumors are characterized by the increased production of reactive oxygen species (ROS), combined with reduced blood flow that leads to low oxygen supply and ER stress. Under these conditions, hypoxia and the unfolded protein response upregulate their target genes. When this occurs, ER oxidoreductases and chaperones become important regulators of tumor growth. However, under these conditions, these proteins not only promote the folding of proteins, but also alter the properties of the plasma membrane and hence modulate tumor immune recognition. For instance, high levels of calreticulin serve as an “eat-me” signal on the surface of tumor cells. Conversely, both intracellular and surface BiP/GRP78 promotes tumor growth. Other ER folding assistants able to modulate the properties of tumor tissue include protein disulfide isomerase (PDI), Ero1α and GRP94. Understanding the roles and mechanisms of ER chaperones in regulating tumor cell functions and immunorecognition will lead to important insight for the development of novel cancer therapies.
Collapse
Affiliation(s)
- Tomás Gutiérrez
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta , Edmonton, AB , Canada
| | - Thomas Simmen
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta , Edmonton, AB , Canada
| |
Collapse
|
24
|
Fossati M, Colombo SF, Borgese N. A positive signal prevents secretory membrane cargo from recycling between the Golgi and the ER. EMBO J 2014; 33:2080-97. [PMID: 25063674 DOI: 10.15252/embj.201488367] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The Golgi complex and ER are dynamically connected by anterograde and retrograde trafficking pathways. To what extent and by what mechanism outward-bound cargo proteins escape retrograde trafficking has been poorly investigated. Here, we analysed the behaviour of several membrane proteins at the ER/Golgi interface in live cells. When Golgi-to-plasma membrane transport was blocked, vesicular stomatitis virus glycoprotein (VSVG), which bears an ER export signal, accumulated in the Golgi, whereas an export signal-deleted version of VSVG attained a steady state determined by the balance of retrograde and anterograde traffic. A similar behaviour was displayed by EGF receptor and by a model tail-anchored protein, whose retrograde traffic was slowed by addition of VSVG's export signal. Retrograde trafficking was energy- and Rab6-dependent, and Rab6 inhibition accelerated signal-deleted VSVG's transport to the cell surface. Our results extend the dynamic bi-directional relationship between the Golgi and ER to include surface-directed proteins, uncover an unanticipated role for export signals at the Golgi complex, and identify recycling as a novel factor that regulates cargo transport out of the early secretory pathway.
Collapse
Affiliation(s)
- Matteo Fossati
- BIOMETRA Department, CNR Institute of Neuroscience, Università degli Studi di Milano, Milano, Italy
| | - Sara F Colombo
- BIOMETRA Department, CNR Institute of Neuroscience, Università degli Studi di Milano, Milano, Italy
| | - Nica Borgese
- BIOMETRA Department, CNR Institute of Neuroscience, Università degli Studi di Milano, Milano, Italy Department of Health Science, Magna Graecia University of Catanzaro, Catanzaro, Italy
| |
Collapse
|
25
|
Parmar HB, Barry C, Duncan R. Polybasic trafficking signal mediates golgi export, ER retention or ER export and retrieval based on membrane-proximity. PLoS One 2014; 9:e94194. [PMID: 24714640 PMCID: PMC3979892 DOI: 10.1371/journal.pone.0094194] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 03/11/2014] [Indexed: 12/25/2022] Open
Abstract
Trafficking of integral membrane proteins between the ER and Golgi complex, and protein sorting and trafficking between the TGN and endosomal/lysosomal compartments or plasma membranes, are dependent on cis-acting, linear amino acid sorting signals. Numerous sorting signals of this type have been identified in the cytoplasmic domains of membrane proteins, several of which rely on basic residues. A novel Golgi export signal that relies on a membrane-proximal polybasic motif (PBM) was recently identified in the reptilian reovirus p14 protein, a representative of an unusual group of bitopic fusion-associated small transmembrane (FAST) proteins encoded by fusogenic orthoreoviruses and responsible for cell-cell fusion and syncytium formation. Using immunofluorescence microscopy, cell surface immunofluorescence, and endoglycosidase H assays, we now show the p14 PBM can mediate several distinct trafficking functions depending on its proximity to the transmembrane domain (TMD). When present within 4-residues of the TMD it serves as a Golgi export signal, but when located at the C-terminus of the 68-residue p14 cytoplasmic endodomain it functions as an ER retention signal. The PBM has no effect on protein trafficking when located at an internal position in the cytoplasmic domain. When present in both membrane-proximal and -distal locations, the PBMs promote export to, and efficient retrieval from, the Golgi complex. Interestingly, the conflicting trafficking signals provided by two PBMs induces extensive ER tubulation and segregation of ER components. These studies highlight how a single trafficking signal in a simple transmembrane protein can have remarkably diverse, position-dependent effects on protein trafficking and ER morphogenesis.
Collapse
Affiliation(s)
- Hirendrasinh B. Parmar
- Department of Microbiology & Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Chris Barry
- Department of Microbiology & Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Roy Duncan
- Department of Microbiology & Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
| |
Collapse
|
26
|
Gershlick DC, de Marcos Lousa C, Foresti O, Lee AJ, Pereira EA, daSilva LL, Bottanelli F, Denecke J. Golgi-dependent transport of vacuolar sorting receptors is regulated by COPII, AP1, and AP4 protein complexes in tobacco. THE PLANT CELL 2014; 26:1308-29. [PMID: 24642936 PMCID: PMC4001386 DOI: 10.1105/tpc.113.122226] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 02/10/2014] [Accepted: 02/18/2014] [Indexed: 05/02/2023]
Abstract
The cycling of vacuolar sorting receptors (VSRs) between early and late secretory pathway compartments is regulated by signals in the cytosolic tail, but the exact pathway is controversial. Here, we show that receptor targeting in tobacco (Nicotiana tabacum) initially involves a canonical coat protein complex II-dependent endoplasmic reticulum-to-Golgi bulk flow route and that VSR-ligand interactions in the cis-Golgi play an important role in vacuolar sorting. We also show that a conserved Glu is required but not sufficient for rate-limiting YXX-mediated receptor trafficking. Protein-protein interaction studies show that the VSR tail interacts with the μ-subunits of plant or mammalian clathrin adaptor complex AP1 and plant AP4 but not that of plant and mammalian AP2. Mutants causing a detour of full-length receptors via the cell surface invariantly cause the secretion of VSR ligands. Therefore, we propose that cycling via the plasma membrane is unlikely to play a role in biosynthetic vacuolar sorting under normal physiological conditions and that the conserved Ile-Met motif is mainly used to recover mistargeted receptors. This occurs via a fundamentally different pathway from the prevacuolar compartment that does not mediate recycling. The role of clathrin and clathrin-independent pathways in vacuolar targeting is discussed.
Collapse
Affiliation(s)
- David C. Gershlick
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Carine de Marcos Lousa
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | | | - Andrew J. Lee
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | | | | | | | - Jurgen Denecke
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| |
Collapse
|
27
|
Parmar HB, Barry C, Kai F, Duncan R. Golgi complex-plasma membrane trafficking directed by an autonomous, tribasic Golgi export signal. Mol Biol Cell 2014; 25:866-78. [PMID: 24451258 PMCID: PMC3952855 DOI: 10.1091/mbc.e13-07-0364] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The first example of a cytosolic, membrane-proximal, tribasic motif required for Golgi export to the plasma membrane is identified and characterized. This novel Golgi export signal can also mediate trafficking of a heterologous Golgi-resident protein, indicating that it functions as an autonomous Golgi export signal. Although numerous linear motifs that direct protein trafficking within cells have been identified, there are few examples of linear sorting signals mediating directed export of membrane proteins from the Golgi complex to the plasma membrane. The reovirus fusion-associated small transmembrane proteins are simple, single-pass transmembrane proteins that traffic through the endoplasmic reticulum–Golgi pathway to the plasma membrane, where they induce cell–cell membrane fusion. Here we show that a membrane-proximal, polybasic motif (PBM) in the cytosolic tail of p14 is essential for efficient export of p14 from the Golgi complex to the plasma membrane. Extensive mutagenic analysis reveals that the number, but not the identity or position, of basic residues present in the PBM dictates p14 export from the Golgi complex, with a minimum of three basic residues required for efficient Golgi export. Results further indicate that the tribasic motif does not affect plasma membrane retention of p14. Furthermore, introduction of the tribasic motif into a Golgi-localized, chimeric ERGIC-53 protein directs export from the Golgi complex to the plasma membrane. The p14 PBM is the first example of an autonomous, tribasic signal required for Golgi export to the plasma membrane.
Collapse
Affiliation(s)
- Hirendrasinh B Parmar
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H 4R2, Canada Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada Department of Pediatrics, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | | | | | | |
Collapse
|
28
|
Hu G, Suo Y, Huang J. A crucial role of the RGS domain in trans-Golgi network export of AtRGS1 in the protein secretory pathway. MOLECULAR PLANT 2013; 6:1933-1944. [PMID: 23793400 DOI: 10.1093/mp/sst109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The secretory pathway is responsible for the transport of newly synthesized transmembrane proteins from the endoplasmic reticulum to their destinations via the Golgi/trans-Golgi network (TGN). Cargo proteins at each station are actively sorted by specific sorting signals on the cargo and the corresponding coat complexes. Here, we used the Arabidopsis regulator of G-protein signaling (AtRGS1), which contains an N-terminal potentially sensing glucose seven-transmembrane domain and a C-terminal RGS domain, as a model to uncover sorting motifs required for its cell surface expression. Expression of wild-type and truncated or mutated AtRGS1 fluorescent fusion proteins identified two cysteine residues in the extracellular N-terminus that are essential for endoplasmic reticulum exit and/or correct folding of AtRGS1. The linker between the seven-transmembrane and RGS domains contains an endoplasmic reticulum export signal, whereas the C-terminus is dispensable for the plasma membrane expression of AtRGS1. Interestingly, deletion of the RGS domain results in Golgi/TGN localization of the truncated AtRGS1. Further analysis using site-directed mutagenesis showed that a tyrosine-based motif embedded in the RGS domain is essential for Golgi/TGN export of AtRGS1. These results reveal a new role for the RGS domain in regulating AtRGS1 trafficking from the Golgi/TGN to the plasma membrane and explain the interaction between the seven-transmembrane and RGS domains.
Collapse
Affiliation(s)
- Guangzhen Hu
- National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Feng Lin Road, Shanghai 200032, China
| | | | | |
Collapse
|
29
|
Lin YC, Chen BM, Lu WC, Su CI, Prijovich ZM, Chung WC, Wu PY, Chen KC, Lee IC, Juan TY, Roffler SR. The B7-1 cytoplasmic tail enhances intracellular transport and mammalian cell surface display of chimeric proteins in the absence of a linear ER export motif. PLoS One 2013; 8:e75084. [PMID: 24073236 PMCID: PMC3779271 DOI: 10.1371/journal.pone.0075084] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 08/12/2013] [Indexed: 11/18/2022] Open
Abstract
Membrane-tethered proteins (mammalian surface display) are increasingly being used for novel therapeutic and biotechnology applications. Maximizing surface expression of chimeric proteins on mammalian cells is important for these applications. We show that the cytoplasmic domain from the B7-1 antigen, a commonly used element for mammalian surface display, can enhance the intracellular transport and surface display of chimeric proteins in a Sar1 and Rab1 dependent fashion. However, mutational, alanine scanning and deletion analysis demonstrate the absence of linear ER export motifs in the B7 cytoplasmic domain. Rather, efficient intracellular transport correlated with the presence of predicted secondary structure in the cytoplasmic tail. Examination of the cytoplasmic domains of 984 human and 782 mouse type I transmembrane proteins revealed that many previously identified ER export motifs are rarely found in the cytoplasmic tail of type I transmembrane proteins. Our results suggest that efficient intracellular transport of B7 chimeric proteins is associated with the structure rather than to the presence of a linear ER export motif in the cytoplasmic tail, and indicate that short (less than ~ 10-20 amino acids) and unstructured cytoplasmic tails should be avoided to express high levels of chimeric proteins on mammalian cells.
Collapse
Affiliation(s)
- Yi-Chieh Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Bing-Mae Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Wei-Cheng Lu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chien-I Su
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | | | - Wen-Chuan Chung
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Pei-Yu Wu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Kai-Chuan Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - I-Chiao Lee
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Ting-Yi Juan
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Steve R. Roffler
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
- * E-mail:
| |
Collapse
|
30
|
Wang J, Chen J, Enns CA, Mayinger P. The first transmembrane domain of lipid phosphatase SAC1 promotes Golgi localization. PLoS One 2013; 8:e71112. [PMID: 23936490 PMCID: PMC3731292 DOI: 10.1371/journal.pone.0071112] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 06/25/2013] [Indexed: 01/30/2023] Open
Abstract
The lipid phosphatase Sac1 cycles between endoplasmic reticulum and cisternal Golgi compartments. In proliferating mammalian cells, a canonical dilysine motif at the C-terminus of Sac1 is required for coatomer complex-I (COP-I)-binding and continuous retrieval to the ER. Starvation triggers accumulation of Sac1 at the Golgi. The mechanism responsible for Golgi retention of Sac1 is unknown. Here we show that the first of the two transmembrane regions in human SAC1 (TM1) functions in Golgi localization. A minimal construct containing only TM1 and the adjacent flanking sequences is concentrated at the Golgi. Transplanting TM1 into transferrin receptor 2 (TfR2) induces Golgi accumulation of this normally plasma membrane and endosomal protein, indicating that TM1 is sufficient for Golgi localization. In addition, we determined that the N-terminal cytoplasmic domain of SAC1 also promotes Golgi localization, even when TM1 is mutated or absent. We conclude that the distribution of SAC1 within the Golgi is controlled via both passive membrane thickness-dependent partitioning of TM1 and a retention mechanism that requires the N-terminal cytoplasmic region.
Collapse
Affiliation(s)
- Jinzhi Wang
- Division of Nephrology & Hypertension, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Juxing Chen
- The Department of Cell & Developmental Biology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Caroline A. Enns
- The Department of Cell & Developmental Biology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Peter Mayinger
- Division of Nephrology & Hypertension, Oregon Health & Science University, Portland, Oregon, United States of America
- * E-mail:
| |
Collapse
|
31
|
Hutt DM, Balch WE. Expanding proteostasis by membrane trafficking networks. Cold Spring Harb Perspect Biol 2013; 5:cshperspect.a013383. [PMID: 23426524 DOI: 10.1101/cshperspect.a013383] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The folding biology common to all three kingdoms of life (Archaea, Bacteria, and Eukarya) is proteostasis. The proteostasis network (PN) functions as a "cloud" to generate, protect, and degrade the proteome. Whereas microbes (Bacteria, Archaea) have a single compartment, Eukarya have numerous subcellular compartments. We examine evidence that Eukarya compartments use coat, tether, and fusion (CTF) membrane trafficking components to form an evolutionarily advanced arm of the PN that we refer to as the "trafficking PN" (TPN). We suggest that the TPN builds compartments by generating a mosaic of integrated cargo-specific trafficking signatures (TRaCKS). TRaCKS control the temporal and spatial features of protein-folding biology based on the Anfinsen principle that the local environment plays a critical role in managing protein structure. TPN-generated endomembrane compartments apply a "quinary" level of structural control to modify the secondary, tertiary, and quaternary structures defined by the primary polypeptide-chain sequence. The development of Anfinsen compartments provides a unifying foundation for understanding the purpose of endomembrane biology and its capacity to drive extant Eukarya function and diversity.
Collapse
Affiliation(s)
- Darren M Hutt
- Department of Cell Biology and Department of Chemical Physiology, The Skaggs Institute for Chemical Biology and the Dorris Institute for Neurological Diseases, The Scripps Research Institute, La Jolla, California 92037, USA
| | | |
Collapse
|
32
|
Frazier SJ, Cohen BN, Lester HA. An engineered glutamate-gated chloride (GluCl) channel for sensitive, consistent neuronal silencing by ivermectin. J Biol Chem 2013; 288:21029-21042. [PMID: 23720773 DOI: 10.1074/jbc.m112.423921] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A modified invertebrate glutamate-gated Cl(-) channel (GluCl αβ) was previously employed to allow pharmacologically induced silencing of electrical activity in CNS neurons upon exposure to the anthelmintic drug ivermectin (IVM). Usefulness of the previous receptor was limited by 1) the high concentration of IVM necessary to elicit a consistent silencing phenotype, raising concern about potential side effects, and 2) the variable extent of neuronal spike suppression, due to variations in the co-expression levels of the fluorescent protein-tagged α and β subunits. To address these issues, mutant receptors generated via rational protein engineering strategies were examined for improvement. Introduction of a gain-of-function mutation (L9'F) in the second transmembrane domain of the α subunit appears to facilitate β subunit incorporation and substantially increase heteromeric GluCl αβ sensitivity to IVM. Removal of an arginine-based endoplasmic reticulum retention motif (RSR mutated to AAA) from the intracellular loop of the β subunit further promotes heteromeric expression at the plasma membrane possibly by preventing endoplasmic reticulum-associated degradation of the β subunit rather than simply reducing endoplasmic reticulum retention. A monomeric XFP (mXFP) mutation that prevents fluorescent protein dimerization complements the mutant channel effects. Expression of the newly engineered GluCl opt α-mXFP L9'F + opt β-mXFP Y182F RSR_AAA receptor in dissociated neuronal cultures markedly increases conductance and reduces variability in spike suppression at 1 nm IVM. This receptor, named "GluClv2.0," is an improved tool for IVM-induced silencing.
Collapse
Affiliation(s)
- Shawnalea J Frazier
- From the Biochemistry and Molecular Biophysics Option and; the Division of Biology, California Institute of Technology, Pasadena, California 91125
| | - Bruce N Cohen
- the Division of Biology, California Institute of Technology, Pasadena, California 91125
| | - Henry A Lester
- the Division of Biology, California Institute of Technology, Pasadena, California 91125.
| |
Collapse
|
33
|
Standley S, Petralia RS, Gravell M, Hamilton R, Wang YX, Schubert M, Wenthold RJ. Trafficking of the NMDAR2B receptor subunit distal cytoplasmic tail from endoplasmic reticulum to the synapse. PLoS One 2012; 7:e39585. [PMID: 22761831 PMCID: PMC3384676 DOI: 10.1371/journal.pone.0039585] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 05/27/2012] [Indexed: 01/24/2023] Open
Abstract
NMDA receptor NR2A/B subunits have PDZ-binding domains on their extreme C-termini that are known to interact with the PSD-95 family and other PDZ proteins. We explore the interactions between PSD-95 family proteins and the NR2A/B cytoplasmic tails, and the consequences of these interactions, from the endoplasmic reticulum (ER) through delivery to the synapse in primary rat hippocampal and cortical cultured neurons. We find that the NR2A/B cytoplasmic tails cluster very early in the secretory pathway and interact serially with SAP102 beginning at the intermediate compartment, and then PSD-95. We further establish that colocalization of the distal C-terminus of NR2B and PSD-95 begins at the trans-Golgi Network (TGN). Formation of NR2B/PSD-95/SAP102 complexes is dependent on the PDZ binding domain of NR2B subunits, but association with SAP102 and PSD-95 plays no distinguishable role in cluster pre-formation or initial targeting to the vicinity of the synapse. Instead the PDZ binding domain plays a role in restricting cell-surface clusters to postsynaptic targets.
Collapse
Affiliation(s)
- Steve Standley
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, California, United States of America.
| | | | | | | | | | | | | |
Collapse
|
34
|
Herzig Y, Sharpe HJ, Elbaz Y, Munro S, Schuldiner M. A systematic approach to pair secretory cargo receptors with their cargo suggests a mechanism for cargo selection by Erv14. PLoS Biol 2012; 10:e1001329. [PMID: 22629230 PMCID: PMC3358343 DOI: 10.1371/journal.pbio.1001329] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 04/03/2012] [Indexed: 11/29/2022] Open
Abstract
A systematic approach to visualize proteins exiting the endoplasmic reticulum paired with their cargo receptors identifies novel cargo for known receptors and reveals the mechanism of one conserved receptor, Erv14. The endoplasmic reticulum (ER) is the site of synthesis of secreted and membrane proteins. To exit the ER, proteins are packaged into COPII vesicles through direct interaction with the COPII coat or aided by specific cargo receptors. Despite the fundamental role of such cargo receptors in protein traffic, only a few have been identified; their cargo spectrum is unknown and the signals they recognize remain poorly understood. We present here an approach we term “PAIRS” (pairing analysis of cargo receptors), which combines systematic genetic manipulations of yeast with automated microscopy screening, to map the spectrum of cargo for a known receptor or to uncover a novel receptor for a particular cargo. Using PAIRS we followed the fate of ∼150 cargos on the background of mutations in nine putative cargo receptors and identified novel cargo for most of these receptors. Deletion of the Erv14 cargo receptor affected the widest range of cargo. Erv14 substrates have a wide array of functions and structures; however, they are all membrane-spanning proteins of the late secretory pathway or plasma membrane. Proteins residing in these organelles have longer transmembrane domains (TMDs). Detailed examination of one cargo supported the hypothesis that Erv14 dependency reflects the length rather than the sequence of the TMD. The PAIRS approach allowed us to uncover new cargo for known cargo receptors and to obtain an unbiased look at specificity in cargo selection. Obtaining the spectrum of cargo for a cargo receptor allows a novel perspective on its mode of action. The rules that appear to guide Erv14 substrate recognition suggest that sorting of membrane proteins at multiple points in the secretory pathway could depend on the physical properties of TMDs. Such a mechanism would allow diverse proteins to utilize a few receptors without the constraints of evolving location-specific sorting motifs. All cells sense their environment, respond to it, and communicate with neighboring cells. To perform these functions, cells use an impressive array of proteins that they display on their surface membranes and secrete into their external environment. Newly synthesized proteins destined for the surface of nucleated cells, or to be secreted into the environment must enter the secretory pathway through the endoplasmic reticulum. Those that reside there remain behind, but most leave for their next destination as cargo proteins in lipid vesicles. To be packaged into vesicles, many of them require a “cargo receptor,” which recognizes and tethers specific cargo proteins in the vesicles. Our study takes a systematic approach to identify the range of cargo proteins that bind to each of the known receptors in yeast. By using this approach, we both discover new cargo for known cargo receptors and delineate the rule that governs cargo selection for one cargo receptor, Erv14. Thus, our study demonstrates a novel approach to identify the cargo for any receptor or to discover new cargo receptors.
Collapse
Affiliation(s)
- Yonatan Herzig
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | | | - Yael Elbaz
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Sean Munro
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
- * E-mail: (SM); (MS)
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
- * E-mail: (SM); (MS)
| |
Collapse
|
35
|
Dong C, Nichols CD, Guo J, Huang W, Lambert NA, Wu G. A triple arg motif mediates α(2B)-adrenergic receptor interaction with Sec24C/D and export. Traffic 2012; 13:857-68. [PMID: 22404651 DOI: 10.1111/j.1600-0854.2012.01351.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 03/07/2012] [Accepted: 03/09/2012] [Indexed: 12/28/2022]
Abstract
Recent studies have demonstrated that cargo exit from the endoplasmic reticulum (ER) may be directed by ER export motifs recognized by components of the coat protein II (COPII) vesicles. However, little is known about ER export motifs and vesicle targeting of the G protein-coupled receptor (GPCR) superfamily. Here, we have demonstrated that a triple Arg (3R) motif in the third intracellular loop functions as a novel ER export signal for α(2B)-adrenergic receptor (α(2B)-AR). The 3R motif mediates α(2B)-AR interaction with Sec24C/D and modulates ER exit, cell surface transport and function of α(2B)-AR. Furthermore, export function of the 3R motif is independent of its position within α(2B)-AR and can be conferred to CD8 glycoprotein. These data provide the first evidence implicating that export of GPCRs is controlled by code-directed interactions with selective components of the COPII transport machinery.
Collapse
Affiliation(s)
- Chunmin Dong
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, 1901 Perdido St, New Orleans, LA 70112, USA
| | | | | | | | | | | |
Collapse
|
36
|
Anterograde trafficking of nascent α(2B)-adrenergic receptor: structural basis, roles of small GTPases. CURRENT TOPICS IN MEMBRANES 2012; 67:79-100. [PMID: 21771486 DOI: 10.1016/b978-0-12-384921-2.00004-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
|
37
|
Abstract
Anterograde trafficking of newly synthesized G protein-coupled -receptors (GPCRs) from the endoplasmic reticulum to the cell surface represents a crucial checkpoint in controlling the amount of the functional receptors at the cell surface and the strength of signaling initiated by the receptors. In contrast to the extensively studied, well-understood endocytic and recycling pathways, the molecular mechanisms underlying the cell-surface targeting of the receptors remain poorly defined. In this chapter, I will discuss current advances in understanding post-Golgi transport of GPCRs by focusing on specific motifs or sequences that may function as sorting signals regulating export from the Golgi and subsequent transport to the plasma membrane of GPCRs.
Collapse
|
38
|
Zhang X, Dong C, Wu QJ, Balch WE, Wu G. Di-acidic motifs in the membrane-distal C termini modulate the transport of angiotensin II receptors from the endoplasmic reticulum to the cell surface. J Biol Chem 2011; 286:20525-35. [PMID: 21507945 DOI: 10.1074/jbc.m111.222034] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The molecular mechanisms underlying the endoplasmic reticulum (ER) export and cell surface transport of nascent G protein-coupled receptors (GPCRs) have just begun to be revealed and previous studies have shown that hydrophobic motifs in the putative amphipathic 8(th) α-helical region within the membrane-proximal C termini play an important role. In this study, we demonstrate that di-acidic motifs in the membrane-distal, nonstructural C-terminal portions are required for the exit from the ER and transport to the plasma membrane of angiotensin II receptors, but not adrenergic receptors. More interestingly, distinct di-acidic motifs dictate optimal export trafficking of different angiotensin II receptors and export ability of each acidic residue in the di-acidic motifs cannot be fully substituted by other acidic residue. Moreover, the function of the di-acidic motifs is likely mediated through facilitating the recruitment of the receptors onto the ER-derived COPII transport vesicles. Therefore, the di-acidic motifs located in the membrane-distal C termini may represent the first linear motifs which recruit selective GPCRs onto the COPII vesicles to control their export from the ER.
Collapse
Affiliation(s)
- Xiaoping Zhang
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
| | | | | | | | | |
Collapse
|
39
|
Sorieul M, Santoni V, Maurel C, Luu DT. Mechanisms and Effects of Retention of Over-Expressed Aquaporin AtPIP2;1 in the Endoplasmic Reticulum. Traffic 2011; 12:473-82. [DOI: 10.1111/j.1600-0854.2010.01154.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
40
|
Miner JJ, Shao B, Wang Y, Chichili GR, Liu Z, Klopocki AG, Yago T, McDaniel JM, Rodgers W, Xia L, McEver RP. Cytoplasmic domain of P-selectin glycoprotein ligand-1 facilitates dimerization and export from the endoplasmic reticulum. J Biol Chem 2011; 286:9577-86. [PMID: 21220419 DOI: 10.1074/jbc.m110.208777] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
P-selectin glycoprotein ligand-1 (PSGL-1) is a homodimeric transmembrane mucin on leukocytes. During inflammation, reversible interactions of PSGL-1 with selectins mediate leukocyte rolling on vascular surfaces. The transmembrane domain of PSGL-1 is required for dimerization, and the cytoplasmic domain propagates signals that activate β(2) integrins to slow rolling on integrin ligands. Leukocytes from knock-in "ΔCD" mice express a truncated PSGL-1 that lacks the cytoplasmic domain. Unexpectedly, they have 10-fold less PSGL-1 on their surfaces than WT leukocytes. Using glycosidases, proteases, Western blotting, confocal microscopy, cell-surface cross-linking, FRET, and pulse-chase metabolic labeling, we demonstrate that deleting the cytoplasmic domain impaired dimerization and delayed export of PSGL-1 from the endoplasmic reticulum (ER), markedly increasing a monomeric precursor in the ER and decreasing mature PSGL-1 on the cell surface. A monomeric full-length PSGL-1 made by substituting the transmembrane domain with that of CD43 exited the ER normally, revealing that dimerization was not required for ER export. Thus, the transmembrane and cytoplasmic domains cooperate to promote dimerization of PSGL-1. Furthermore, the cytoplasmic domain provides a key signal to export precursors of PSGL-1 from the ER to the Golgi apparatus en route to the cell surface.
Collapse
Affiliation(s)
- Jonathan J Miner
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Moriyama K, Sitkovsky MV. Adenosine A2A receptor is involved in cell surface expression of A2B receptor. J Biol Chem 2010; 285:39271-88. [PMID: 20926384 PMCID: PMC2998132 DOI: 10.1074/jbc.m109.098293] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 10/05/2010] [Indexed: 11/06/2022] Open
Abstract
The A2A and A2B adenosine receptors (A2AR and A2BR) are implicated in many physiological processes. However, the mechanisms of their intracellular maturation and trafficking are poorly understood. In comparative studies of A2AR versus A2BR expression in transfected cells, we noticed that the levels of cell surface expression of A2BR were significantly lower than those of A2AR. A large portion of the A2BR was degraded by the proteasome. Studies of cell surface expression of A2BR chimeric molecules in transfectants suggested that A2BR does not have the dominant forward transport signal for export from the endoplasmic reticulum to the cell surface. A2BR surface expression was increased in A2BR chimeras where the A2BR carboxyl terminus (CT) was replaced or fused with the A2AR CT. Co-transfection of A2AR with A2BR enhanced surface expression of A2BR though the F(X)(6)LL motif in the A2AR CT. The requirements of A2AR expression for better A2BR cell surface expression was not only established in transfectants but also confirmed by observations of much lower levels of A2BR-induced intracellular cAMP accumulation in response to A2BR-activating ligand in splenocytes from A2AR(-/-) mice than in wild type mice. The results of mechanistic studies suggested that poor A2BR expression at the cell surface might be accounted for mainly by the lack of a dominant forward transport signal from the endoplasmic reticulum to the plasma membrane; it is likely that A2BR forms a hetero-oligomer complex for better function.
Collapse
Affiliation(s)
- Kengo Moriyama
- From the New England Inflammation and Tissue Protection Institute, Departments of Pharmaceutical Science and Biology, Northeastern University, Boston, Massachusetts 02115
| | - Michail V. Sitkovsky
- From the New England Inflammation and Tissue Protection Institute, Departments of Pharmaceutical Science and Biology, Northeastern University, Boston, Massachusetts 02115
| |
Collapse
|
42
|
Kawaguchi S, Hsu CL, Ng DTW. Interplay of substrate retention and export signals in endoplasmic reticulum quality control. PLoS One 2010; 5:e15532. [PMID: 21151492 PMCID: PMC2991357 DOI: 10.1371/journal.pone.0015532] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Accepted: 10/05/2010] [Indexed: 11/19/2022] Open
Abstract
Background Endoplasmic reticulum (ER) quality control mechanisms are part of a comprehensive system to manage cell stress. The flux of molecules is monitored to retain folding intermediates and target misfolded molecules to ER-associated degradation (ERAD) pathways. The mechanisms of sorting remain unclear. While some proteins are retained statically, the classical model substrate CPY* is found in COPII transport vesicles, suggesting a retrieval mechanism for retention. However, its management can be even more dynamic. If ERAD is saturated under stress, excess CPY* traffics to the vacuole for degradation. These observations suggest that misfolded proteins might display different signals for their management. Methodology/Principal Findings Here, we report the existence of a functional ER exit signal in the pro-domain of CPY*. Compromising its integrity causes ER retention through exclusion from COPII vesicles. The signal co-exists with other signals used for retention and degradation. Physiologically, the export signal is important for stress tolerance. Disabling it converts a benign protein into one that is intrinsically cytotoxic. Conclusions/Significance These data reveal the remarkable interplay between opposing signals embedded within ERAD substrate molecules and the mechanisms that decipher them. Our findings demonstrate the diversity of mechanisms deployed for protein quality control and maintenance of protein homeostasis.
Collapse
Affiliation(s)
- Shinichi Kawaguchi
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore
| | - Chia-Ling Hsu
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore
| | - Davis T. W. Ng
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- * E-mail:
| |
Collapse
|
43
|
Sharp TM, Guix S, Katayama K, Crawford SE, Estes MK. Inhibition of cellular protein secretion by norwalk virus nonstructural protein p22 requires a mimic of an endoplasmic reticulum export signal. PLoS One 2010; 5:e13130. [PMID: 20976190 PMCID: PMC2956632 DOI: 10.1371/journal.pone.0013130] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 09/02/2010] [Indexed: 12/22/2022] Open
Abstract
Protein trafficking between the endoplasmic reticulum (ER) and Golgi apparatus is central to cellular homeostasis. ER export signals are utilized by a subset of proteins to rapidly exit the ER by direct uptake into COPII vesicles for transport to the Golgi. Norwalk virus nonstructural protein p22 contains a YXΦESDG motif that mimics a di-acidic ER export signal in both sequence and function. However, unlike normal ER export signals, the ER export signal mimic of p22 is necessary for apparent inhibition of normal COPII vesicle trafficking, which leads to Golgi disassembly and antagonism of Golgi-dependent cellular protein secretion. This is the first reported function for p22. Disassembly of the Golgi apparatus was also observed in cells replicating Norwalk virus, which may contribute to pathogenesis by interfering with cellular processes that are dependent on an intact secretory pathway. These results indicate that the ER export signal mimic is critical to the antagonistic function of p22, shown herein to be a novel antagonist of ER/Golgi trafficking. This unique and well-conserved human norovirus motif is therefore an appealing target for antiviral drug development.
Collapse
Affiliation(s)
- Tyler M. Sharp
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Susana Guix
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Kazuhiko Katayama
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Sue E. Crawford
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Mary K. Estes
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| |
Collapse
|
44
|
Errasti-Murugarren E, Casado FJ, Pastor-Anglada M. Different N-terminal motifs determine plasma membrane targeting of the human concentrative nucleoside transporter 3 in polarized and nonpolarized cells. Mol Pharmacol 2010; 78:795-803. [PMID: 20643903 DOI: 10.1124/mol.110.065920] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Human concentrative nucleoside transporter 3 (hCNT3) is a broad-selectivity, high-affinity protein implicated in the uptake of most nucleoside-derived anticancer and antiviral drugs. Regulated trafficking of hCNT3 has been recently postulated as a suitable way to improve nucleoside-based therapies. Moreover, the recent identification of a putative novel hCNT3-type transporter lacking the first 69 amino acids and retained at the endoplasmic reticulum anticipated that the N terminus of hCNT3 contains critical motifs implicated in trafficking. In the current study, we have addressed this issue by using deletions and site-directed mutagenesis and plasma membrane expression and nucleoside uptake kinetic analysis. Data reveal that 1) a segment between amino acids 50 and 62 contains plasma membrane-sorting determinants in nonpolarized cells; 2) in particular, the Val(57)-Thr(58)-Val(59) tripeptide seems to be the core of the export signal, whereas acidic motifs upstream and downstream of it seem to be important for the kinetics of the process; and 3) in polarized epithelia, the β-turn-forming motif (17)VGFQ(20) is necessary for proper apical expression of the protein.
Collapse
Affiliation(s)
- Ekaitz Errasti-Murugarren
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona and CIBER EHD, Avda Diagonal 645, Edifici annex, Planta-1, 08028 Barcelona, Spain
| | | | | |
Collapse
|
45
|
Renard HF, Demaegd D, Guerriat B, Morsomme P. Efficient ER exit and vacuole targeting of yeast Sna2p require two tyrosine-based sorting motifs. Traffic 2010; 11:931-46. [PMID: 20406419 DOI: 10.1111/j.1600-0854.2010.01070.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
SNA (Sensitive to Na(+)) proteins form a membrane protein family, which, in the yeast Saccharomyces cerevisiae, is composed of four members: Sna1p/Pmp3p, Sna2p, Sna3p and Sna4p. In this study, we focused on the 79 residue Sna2p protein. We found that Sna2p is localized in the vacuolar membrane. Directed mutagenesis showed that two functional tyrosine motifs YXXØ are present in the C-terminal region. Each of these is involved in a different Golgi-to-vacuole targeting pathway: the tyrosine 65 motif is involved in adaptor protein (AP-1)-dependent targeting, whereas the tyrosine 75 motif is involved in AP-3-dependent targeting. Moreover, our data suggest that these motifs also play a crucial role in the exit of Sna2p from the endoplasmic reticulum (ER). Directed mutagenesis of these tyrosines led to a partial redirection of Sna2p to lipid bodies, probably because of a decrease in ER exit efficiency. Sna2p is the first yeast protein in which two YXXØ motifs have been identified and both were shown to be functional at two different steps of the secretory pathway, ER exit and Golgi-to-vacuole transport.
Collapse
Affiliation(s)
- Henri-François Renard
- Université catholique de Louvain, Institut des Sciences de la Vie, Croix du Sud 4/15, B-1348 Louvain-la-Neuve, Belgium
| | | | | | | |
Collapse
|
46
|
|
47
|
Lang SM, Means RE. Characterization of cytoplasmic motifs important in rhesus rhadinovirus gB processing and trafficking. Virology 2010; 398:233-42. [PMID: 20060555 DOI: 10.1016/j.virol.2009.12.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 11/09/2009] [Accepted: 12/02/2009] [Indexed: 12/13/2022]
Abstract
Rhesus monkey rhadinovirus (RRV) is highly related to Kaposi's sarcoma-associated herpesvirus (KSHV), a human gamma-herpesvirus etiologically-linked with several cancers. Glycoprotein B (gB) homologues are encoded by all herpesviruses and play a role in virus attachment, entry, and in egress. We have found that RRV gB, like KSHV gB, is cleaved at a consensus furin cleavage site and is modified by both N-linked and O-linked glycosylation. Mutagenesis of three tyrosine- based trafficking motifs, a diacidic tyrosine motif, and a di-lucine motif in the cytoplasmic region revealed a role for these sequences in both ER export and endocytosis from the plasma membrane. These experiments provide a basis for further experiments looking at gB incorporation and role in gamma-herpesvirus assembly and egress.
Collapse
Affiliation(s)
- Sabine M Lang
- Department Of Pathology, Yale University School of Medicine, P.O. Box 208023, New Haven, CT 06520, USA
| | | |
Collapse
|
48
|
Hayer A, Stoeber M, Bissig C, Helenius A. Biogenesis of caveolae: stepwise assembly of large caveolin and cavin complexes. Traffic 2009; 11:361-82. [PMID: 20070607 DOI: 10.1111/j.1600-0854.2009.01023.x] [Citation(s) in RCA: 188] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We analyzed the assembly of caveolae in CV1 cells by following the fate of newly synthesized caveolin-1 (CAV1), caveolin-2 and polymerase I and transcript release factor (PTRF)/cavin-1 biochemically and using live-cell imaging. Immediately after synthesis in the endoplasmic reticulum (ER), CAV1 assembled into 8S complexes that concentrated in ER exit sites, due to a DXE sequence in the N-terminal domain. The coat protein II (COPII) machinery allowed rapid transport to the Golgi complex. Accumulating in the medial Golgi, the caveolins lost their diffusional mobility, underwent conformational changes, associated with cholesterol, and eventually assembled into 70S complexes. Together with green fluorescent protein-glycosyl-phosphatidylinositol (GFP-GPI), the newly assembled caveolin scaffolds underwent transport to the plasma membrane in vesicular carriers distinct from those containing vesicular stomatitis virus (VSV) G-protein. After arrival, PTRF/cavin-1 was recruited to the caveolar domains over a period of 25 min or longer. PTRF/cavin-1 itself was present in 60S complexes that also formed in the absence of CAV1. Our study showed the existence of two novel large complexes containing caveolar coat components, and identified a hierarchy of events required for caveolae assembly occurring stepwise in three distinct locations--the ER, the Golgi complex and the plasma membrane.
Collapse
Affiliation(s)
- Arnold Hayer
- ETH Zurich, Institute of Biochemistry, HPM, 8093 Zurich, Switzerland
| | | | | | | |
Collapse
|
49
|
Sakai K, Hamanaka R, Yuki H, Watanabe M. A novel fractionation method of the rough ER integral membrane proteins; resident proteins versus exported proteins? Proteomics 2009; 9:3036-46. [PMID: 19526556 DOI: 10.1002/pmic.200800803] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We treated the high salt-washed canine pancreatic rough ER (KRM) with 0.18% Triton X-100, separated the extract from the residual membrane (0.18%Tx KRM), and processed the extract with SM-2 beads to recover membrane proteins in proteoliposomes. To focus on integral membrane proteins, KRM, 0.18%Tx KRM and proteoliposomes were subjected to sodium carbonate treatment, and analyzed by 2-D gel electrophoresis. Consequently we found that a distinct group of integral membrane protein of KRM preferentially extracted from the membrane and recovered in proteoliposomes did exist, while majority of KRM integral membrane proteins were fractionated in 0.18%Tx KRM, which retained the basic structure and functions of KRM. Protein identification showed that the former group was enriched with proteins exported from the ER and the latter group comprised mostly of ER resident proteins. This result will potentially affect the prevailing view of the ER membrane structure as well as protein sorting from the ER.
Collapse
Affiliation(s)
- Kumiko Sakai
- Department of Cell Biology, Faculty of Medicine, Oita University, Yufu-Shi, Oita, Japan
| | | | | | | |
Collapse
|
50
|
Mikosch M, Käberich K, Homann U. ER export of KAT1 is correlated to the number of acidic residues within a triacidic motif. Traffic 2009; 10:1481-7. [PMID: 19659502 DOI: 10.1111/j.1600-0854.2009.00962.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
For a number of ion channels, including the potassium (K(+)) inward rectifying channel from Arabidopsis thaliana (KAT1), diacidic endoplasmic reticulum (ER) export motifs have been identified. These motifs consist of two acidic amino acids (aspartate (D) and/or glutamate (E)) separated by any amino acid. To specify the role of single acidic amino acids for efficiency of ER export, we analysed a sequence of KAT1 that included the originally identified diacidic ER export motif (DxE) plus an additional D just upstream of the diacidic motif. Analysis of single, double and triple mutations of the acidic amino acids of the DxDxE motif revealed a gradual reduction of ER export depending on the number of mutated acidic residues. The amount of reduction in ER export was not related to the position, but only to the number of mutated acidic amino acids. These results show that a triacidic motif is essential for efficient ER export of KAT1. Function of the triacidic motif probably involves cooperative binding to Sec24.
Collapse
Affiliation(s)
- Melanie Mikosch
- Institute of Botany, Technische Universität Darmstadt, Darmstadt, Germany
| | | | | |
Collapse
|