201
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Shiwarski DJ, Darr M, Telmer CA, Bruchez MP, Puthenveedu MA. PI3K class II α regulates δ-opioid receptor export from the trans-Golgi network. Mol Biol Cell 2017; 28:2202-2219. [PMID: 28566554 PMCID: PMC5531736 DOI: 10.1091/mbc.e17-01-0030] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 04/26/2017] [Accepted: 05/23/2017] [Indexed: 12/20/2022] Open
Abstract
The interplay between signaling and trafficking by G protein-coupled receptors (GPCRs) has focused mainly on endocytic trafficking. Whether and how surface delivery of newly synthesized GPCRs is regulated by extracellular signals is less understood. Here we define a signaling-regulated checkpoint at the trans-Golgi network (TGN) that controls the surface delivery of the delta opioid receptor (δR). In PC12 cells, inhibition of phosphoinositide-3 kinase (PI3K) activity blocked export of newly synthesized δR from the Golgi and delivery to the cell surface, similar to treatment with nerve growth factor (NGF). Depletion of class II phosphoinositide-3 kinase α (PI3K C2A), but not inhibition of class I PI3K, blocked δR export to comparable levels and attenuated δR-mediated cAMP inhibition. NGF treatment displaced PI3K C2A from the Golgi and optogenetic recruitment of the PI3K C2A kinase domain to the TGN-induced δR export downstream of NGF. Of importance, PI3K C2A expression promotes export of endogenous δR in primary trigeminal ganglion neurons. Taken together, our results identify PI3K C2A as being required and sufficient for δR export and surface delivery in neuronal cells and suggest that it could be a key modulator of a novel Golgi export checkpoint that coordinates GPCR delivery to the surface.
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Affiliation(s)
- Daniel J Shiwarski
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213.,Center for the Neural Basis of Cognition, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Marlena Darr
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Cheryl A Telmer
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Marcel P Bruchez
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213.,Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213.,Molecular Biosensor and Imaging Center, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Manojkumar A Puthenveedu
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213 .,Center for the Neural Basis of Cognition, Carnegie Mellon University, Pittsburgh, PA 15213
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202
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Campelo F, van Galen J, Turacchio G, Parashuraman S, Kozlov MM, García-Parajo MF, Malhotra V. Sphingomyelin metabolism controls the shape and function of the Golgi cisternae. eLife 2017; 6. [PMID: 28500756 PMCID: PMC5462544 DOI: 10.7554/elife.24603] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 05/04/2017] [Indexed: 12/11/2022] Open
Abstract
The flat Golgi cisterna is a highly conserved feature of eukaryotic cells, but how is this morphology achieved and is it related to its function in cargo sorting and export? A physical model of cisterna morphology led us to propose that sphingomyelin (SM) metabolism at the trans-Golgi membranes in mammalian cells essentially controls the structural features of a Golgi cisterna by regulating its association to curvature-generating proteins. An experimental test of this hypothesis revealed that affecting SM homeostasis converted flat cisternae into highly curled membranes with a concomitant dissociation of membrane curvature-generating proteins. These data lend support to our hypothesis that SM metabolism controls the structural organization of a Golgi cisterna. Together with our previously presented role of SM in controlling the location of proteins involved in glycosylation and vesicle formation, our data reveal the significance of SM metabolism in the structural organization and function of Golgi cisternae. DOI:http://dx.doi.org/10.7554/eLife.24603.001 The Golgi complex is a hub inside cells that transports many proteins to various parts of the cell. It also receives freshly made proteins and modifies them to help them mature into their final active forms. The complex is made up of a stack of disc-like membrane structures called cisternae. Are the shapes of the cisternae important for the Golgi complex to work properly? Membranes are made of mixtures of molecules known as lipids and proteins. Previous experiments show that when the mixture of lipids in the Golgi membranes changes in a specific manner, the cisternae curl into an onion-like shape and the Golgi cannot process or send out proteins anymore. Campelo et al. used mathematics and experimental approaches to investigate what causes the Golgi to change shape when the lipid mixture of the cisternae changes. A mathematical description of the shape of the Golgi predicted that some proteins keep the cisternae flat by holding the membrane rim that connects the two faces of a cisterna. To test this prediction, Campelo et al. performed experiments in human cells, which showed that when the mixture of lipids in the Golgi membranes changes, certain proteins jump from the rim, causing the cisternae to curl. These same proteins are also needed to transport cargo proteins out of the Golgi, meaning that there is a connection between the shape of the Golgi and the tasks it carries out. The shape of the Golgi complex is altered in Alzheimer’s disease and many other neurodegenerative diseases. The next challenges are to understand how these shape changes happen, how this affects cells, and if it could be possible to develop drugs that prevent these changes from occurring in patients. DOI:http://dx.doi.org/10.7554/eLife.24603.002
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Affiliation(s)
- Felix Campelo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Josse van Galen
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain
| | - Gabriele Turacchio
- Institute of Protein Biochemistry, National Research Council of Italy, Naples, Italy
| | | | - Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - María F García-Parajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Vivek Malhotra
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain
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203
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Capasso S, Sticco L, Rizzo R, Pirozzi M, Russo D, Dathan NA, Campelo F, van Galen J, Hölttä-Vuori M, Turacchio G, Hausser A, Malhotra V, Riezman I, Riezman H, Ikonen E, Luberto C, Parashuraman S, Luini A, D'Angelo G. Sphingolipid metabolic flow controls phosphoinositide turnover at the trans-Golgi network. EMBO J 2017; 36:1736-1754. [PMID: 28495678 DOI: 10.15252/embj.201696048] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 03/31/2017] [Accepted: 04/04/2017] [Indexed: 11/09/2022] Open
Abstract
Sphingolipids are membrane lipids globally required for eukaryotic life. The sphingolipid content varies among endomembranes with pre- and post-Golgi compartments being poor and rich in sphingolipids, respectively. Due to this different sphingolipid content, pre- and post-Golgi membranes serve different cellular functions. The basis for maintaining distinct subcellular sphingolipid levels in the presence of membrane trafficking and metabolic fluxes is only partially understood. Here, we describe a homeostatic regulatory circuit that controls sphingolipid levels at the trans-Golgi network (TGN). Specifically, we show that sphingomyelin production at the TGN triggers a signalling pathway leading to PtdIns(4)P dephosphorylation. Since PtdIns(4)P is required for cholesterol and sphingolipid transport to the trans-Golgi network, PtdIns(4)P consumption interrupts this transport in response to excessive sphingomyelin production. Based on this evidence, we envisage a model where this homeostatic circuit maintains a constant lipid composition in the trans-Golgi network and post-Golgi compartments, thus counteracting fluctuations in the sphingolipid biosynthetic flow.
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Affiliation(s)
- Serena Capasso
- Istituto di Ricovero e Cura a Carattere Scientifico-SDN, Naples, Italy
| | - Lucia Sticco
- Institute of Protein Biochemistry-National Research Council, Naples, Italy
| | - Riccardo Rizzo
- Institute of Protein Biochemistry-National Research Council, Naples, Italy
| | - Marinella Pirozzi
- Institute of Protein Biochemistry-National Research Council, Naples, Italy
| | - Domenico Russo
- Institute of Protein Biochemistry-National Research Council, Naples, Italy
| | - Nina A Dathan
- Institute of Protein Biochemistry-National Research Council, Naples, Italy
| | - Felix Campelo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain
| | - Josse van Galen
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain
| | - Maarit Hölttä-Vuori
- Department of Anatomy, Faculty of Medicine, Minerva Research Institute for Medical Research, University of Helsinki, Helsinki, Finland
| | - Gabriele Turacchio
- Institute of Protein Biochemistry-National Research Council, Naples, Italy
| | - Angelika Hausser
- Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, Germany
| | - Vivek Malhotra
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
| | - Isabelle Riezman
- Department of Biochemistry, NCCR Chemical Biology, University of Geneva, Geneva, Switzerland
| | - Howard Riezman
- Department of Biochemistry, NCCR Chemical Biology, University of Geneva, Geneva, Switzerland
| | - Elina Ikonen
- Department of Anatomy, Faculty of Medicine, Minerva Research Institute for Medical Research, University of Helsinki, Helsinki, Finland
| | - Chiara Luberto
- Stony Brook Cancer Center, Health Science Center, Stony Brook University, Stony Brook, NY, USA
| | | | - Alberto Luini
- Istituto di Ricovero e Cura a Carattere Scientifico-SDN, Naples, Italy.,Institute of Protein Biochemistry-National Research Council, Naples, Italy
| | - Giovanni D'Angelo
- Istituto di Ricovero e Cura a Carattere Scientifico-SDN, Naples, Italy .,Institute of Protein Biochemistry-National Research Council, Naples, Italy
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204
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Abstract
ADP-ribosylation factors (Arfs) and ADP-ribosylation factor-like proteins (Arls) are highly conserved small GTPases that function as main regulators of vesicular trafficking and cytoskeletal reorganization. Arl1, the first identified member of the large Arl family, is an important regulator of Golgi complex structure and function in organisms ranging from yeast to mammals. Together with its effectors, Arl1 has been shown to be involved in several cellular processes, including endosomal trans-Golgi network and secretory trafficking, lipid droplet and salivary granule formation, innate immunity and neuronal development, stress tolerance, as well as the response of the unfolded protein. In this Commentary, we provide a comprehensive summary of the Arl1-dependent cellular functions and a detailed characterization of several Arl1 effectors. We propose that involvement of Arl1 in these diverse cellular functions reflects the fact that Arl1 is activated at several late-Golgi sites, corresponding to specific molecular complexes that respond to and integrate multiple signals. We also provide insight into how the GTP-GDP cycle of Arl1 is regulated, and highlight a newly discovered mechanism that controls the sophisticated regulation of Arl1 activity at the Golgi complex.
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Affiliation(s)
- Chia-Jung Yu
- Department of Cell and Molecular Biology, College of Medicine, Chang Gung University, Linkou, Tao-Yuan 33302, Taiwan.,Department of Thoracic Medicine, Chang Gung Memorial Hospital, Linkou, Tao-Yuan 33305, Taiwan
| | - Fang-Jen S Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan .,Department of Medical Research, National Taiwan University Hospital, Taipei 10002, Taiwan
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205
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Lipid transfer proteins and the tuning of compartmental identity in the Golgi apparatus. Chem Phys Lipids 2016; 200:42-61. [DOI: 10.1016/j.chemphyslip.2016.06.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 06/21/2016] [Accepted: 06/22/2016] [Indexed: 11/23/2022]
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206
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Abstract
Acidic phospholipids are minor membrane lipids but critically important for signaling events. The main acidic phospholipids are phosphatidylinositol phosphates (PIPs also known as phosphoinositides), phosphatidylserine (PS), and phosphatidic acid (PA). Acidic phospholipids are precursors of second messengers of key signaling cascades or are second messengers themselves. They regulate the localization and activation of many proteins, and are involved in virtually all membrane trafficking events. As such, it is crucial to understand the subcellular localization and dynamics of each of these lipids within the cell. Over the years, several techniques have emerged in either fixed or live cells to analyze the subcellular localization and dynamics of acidic phospholipids. In this chapter, we review one of them: the use of genetically encoded biosensors that are based on the expression of specific lipid binding domains (LBDs) fused to fluorescent proteins. We discuss how to design such sensors, including the criteria for selecting the lipid binding domains of interest and to validate them. We also emphasize the care that must be taken during data analysis as well as the main limitations and advantages of this approach.
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Affiliation(s)
- Matthieu Pierre Platre
- Laboratoire de Reproduction et Développement des Plantes, CNRS, INRA, ENS Lyon, UCBL, Université de Lyon, 46 Allée d'Italie, 69364, Lyon Cedex 07, France
| | - Yvon Jaillais
- Laboratoire de Reproduction et Développement des Plantes, CNRS, INRA, ENS Lyon, UCBL, Université de Lyon, 46 Allée d'Italie, 69364, Lyon Cedex 07, France.
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207
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Tanguy E, Carmon O, Wang Q, Jeandel L, Chasserot-Golaz S, Montero-Hadjadje M, Vitale N. Lipids implicated in the journey of a secretory granule: from biogenesis to fusion. J Neurochem 2016; 137:904-12. [PMID: 26877188 DOI: 10.1111/jnc.13577] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 01/20/2016] [Accepted: 02/03/2016] [Indexed: 01/01/2023]
Abstract
The regulated secretory pathway begins with the formation of secretory granules by budding from the Golgi apparatus and ends by their fusion with the plasma membrane leading to the release of their content into the extracellular space, generally following a rise in cytosolic calcium. Generation of these membrane-bound transport carriers can be classified into three steps: (i) cargo sorting that segregates the cargo from resident proteins of the Golgi apparatus, (ii) membrane budding that encloses the cargo and depends on the creation of appropriate membrane curvature, and (iii) membrane fission events allowing the nascent carrier to separate from the donor membrane. These secretory vesicles then mature as they are actively transported along microtubules toward the cortical actin network at the cell periphery. The final stage known as regulated exocytosis involves the docking and the priming of the mature granules, necessary for merging of vesicular and plasma membranes, and the subsequent partial or total release of the secretory vesicle content. Here, we review the latest evidence detailing the functional roles played by lipids during secretory granule biogenesis, recruitment, and exocytosis steps. In this review, we highlight evidence supporting the notion that lipids play important functions in secretory vesicle biogenesis, maturation, recruitment, and membrane fusion steps. These effects include regulating various protein distribution and activity, but also directly modulating membrane topology. The challenges ahead to understand the pleiotropic functions of lipids in a secretory granule's journey are also discussed. This article is part of a mini review series on Chromaffin cells (ISCCB Meeting, 2015).
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Affiliation(s)
- Emeline Tanguy
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique & Université de Strasbourg, Strasbourg, France
| | - Ophélie Carmon
- INSERM U982, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale, Université de Rouen, Mont-Saint-Aignan, France
| | - Qili Wang
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique & Université de Strasbourg, Strasbourg, France
| | - Lydie Jeandel
- INSERM U982, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale, Université de Rouen, Mont-Saint-Aignan, France
| | - Sylvette Chasserot-Golaz
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique & Université de Strasbourg, Strasbourg, France
| | - Maité Montero-Hadjadje
- INSERM U982, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale, Université de Rouen, Mont-Saint-Aignan, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR-3212 Centre National de la Recherche Scientifique & Université de Strasbourg, Strasbourg, France
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208
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Picas L, Gaits-Iacovoni F, Goud B. The emerging role of phosphoinositide clustering in intracellular trafficking and signal transduction. F1000Res 2016; 5. [PMID: 27092250 PMCID: PMC4821294 DOI: 10.12688/f1000research.7537.1] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/23/2016] [Indexed: 01/03/2023] Open
Abstract
Phosphoinositides are master regulators of multiple cellular processes: from vesicular trafficking to signaling, cytoskeleton dynamics, and cell growth. They are synthesized by the spatiotemporal regulated activity of phosphoinositide-metabolizing enzymes. The recent observation that some protein modules are able to cluster phosphoinositides suggests that alternative or complementary mechanisms might operate to stabilize the different phosphoinositide pools within cellular compartments. Herein, we discuss the different known and potential molecular players that are prone to engage phosphoinositide clustering and elaborate on how such a mechanism might take part in the regulation of intracellular trafficking and signal transduction.
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Affiliation(s)
- Laura Picas
- Centre de Biochimie Structurale, CNRS UMR 5048, INSERM U1054, Université de Montpellier, Montpellier, France
| | - Frederique Gaits-Iacovoni
- INSERM, UMR1048, Université Toulouse III, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Bruno Goud
- Institut Curie, PSL Research University, CNRS UMR 144, Paris, France
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209
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Foissner I, Sommer A, Hoeftberger M, Hoepflinger MC, Absolonova M. Is Wortmannin-Induced Reorganization of the trans-Golgi Network the Key to Explain Charasome Formation? FRONTIERS IN PLANT SCIENCE 2016; 7:756. [PMID: 27375631 PMCID: PMC4891338 DOI: 10.3389/fpls.2016.00756] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 05/17/2016] [Indexed: 05/18/2023]
Abstract
Wortmannin, a fungal metabolite and an inhibitor of phosphatidylinositol-3 (PI3) and phosphatidylinositol-4 (PI4) kinases, is widely used for the investigation and dissection of vacuolar trafficking routes and for the identification of proteins located at multivesicular bodies (MVBs). In this study, we applied wortmannin on internodal cells of the characean green alga Chara australis. Wortmannin was used at concentrations of 25 and 50 μM which, unlike in other cells, arrested neither constitutive, nor wounding-induced endocytosis via coated vesicles. Wortmannin caused the formation of "mixed compartments" consisting of MVBs and membranous tubules which were probably derived from the trans-Golgi network (TGN) and within these compartments MVBs fused into larger organelles. Most interestingly, wortmannin also caused pronounced changes in the morphology of the TGNs. After transient hypertrophy, the TGNs lost their coat and formed compact, three-dimensional meshworks of anastomosing tubules containing a central core. These meshworks had a size of up to 4 μm and a striking resemblance to charasomes, which are convoluted plasma membrane domains, and which serve to increase the area available for transporters. Our findings indicate that similar mechanisms are responsible for the formation of charasomes and the wortmannin-induced reorganization of the TGN. We hypothesize that both organelles grow because of a disturbance of clathrin-dependent membrane retrieval due to inhibition of PI3 and/or PI4 kinases. This leads to local inhibition of clathrin-mediated endocytosis during charasome formation in untreated cells and to inhibition of vesicle release from the TGN in wortmannin-treated cells, respectively. The morphological resemblance between charasomes and wortmannin-modified TGN compartments suggests that homologous proteins are involved in membrane curvature and organelle architecture.
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210
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Eiseler T, Wille C, Koehler C, Illing A, Seufferlein T. Protein Kinase D2 Assembles a Multiprotein Complex at the Trans-Golgi Network to Regulate Matrix Metalloproteinase Secretion. J Biol Chem 2015; 291:462-77. [PMID: 26507660 DOI: 10.1074/jbc.m115.673582] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Indexed: 11/06/2022] Open
Abstract
Vesicle formation and fission are tightly regulated at the trans-Golgi network (TGN) during constitutive secretion. Two major protein families regulate these processes: members of the adenosyl-ribosylation factor family of small G-proteins (ARFs) and the protein kinase D (PKD) family of serine/threonine kinases. The functional relationship between these two key regulators of protein transport from the TGN so far is elusive. We here demonstrate the assembly of a novel functional protein complex at the TGN and its key members: cytosolic PKD2 binds ARF-like GTPase (ARL1) and shuttles ARL1 to the TGN. ARL1, in turn, localizes Arfaptin2 to the TGN. At the TGN, where PKD2 interacts with active ARF1, PKD2, and ARL1 are required for the assembly of a complex comprising of ARF1 and Arfaptin2 leading to secretion of matrix metalloproteinase-2 and -7. In conclusion, our data indicate that PKD2 is a core factor in the formation of this multiprotein complex at the TGN that controls constitutive secretion of matrix metalloproteinase cargo.
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Affiliation(s)
- Tim Eiseler
- From the Department of Internal Medicine I, Ulm University, Albert Einstein Allee 23, D-89081 Ulm, Germany and
| | - Christoph Wille
- From the Department of Internal Medicine I, Ulm University, Albert Einstein Allee 23, D-89081 Ulm, Germany and
| | - Conny Koehler
- the Department of Internal Medicine I, Martin-Luther University Halle-Wittenberg, Ernst-Grube, Strasse 40, D-06120 Halle (Saale), Germany
| | - Anett Illing
- From the Department of Internal Medicine I, Ulm University, Albert Einstein Allee 23, D-89081 Ulm, Germany and
| | - Thomas Seufferlein
- From the Department of Internal Medicine I, Ulm University, Albert Einstein Allee 23, D-89081 Ulm, Germany and
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211
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Huang LH, Lee WC, You ST, Cheng CC, Yu CJ. Arfaptin-1 negatively regulates Arl1-mediated retrograde transport. PLoS One 2015; 10:e0118743. [PMID: 25789876 PMCID: PMC4366199 DOI: 10.1371/journal.pone.0118743] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 01/11/2015] [Indexed: 12/24/2022] Open
Abstract
The small GTPase Arf-like protein 1 (Arl1) is well known for its role in intracellular vesicular transport at the trans-Golgi network (TGN). In this study, we used differential affinity chromatography combined with mass spectrometry to identify Arf-interacting protein 1b (arfaptin-1b) as an Arl1-interacting protein and characterized a novel function for arfaptin-1 (including the arfaptin-1a and 1b isoforms) in Arl1-mediated retrograde transport. Using a Shiga-toxin subunit B (STxB) transportation assay, we demonstrated that knockdown of arfaptin-1 accelerated the retrograde transport of STxB from the endosome to the Golgi apparatus, whereas Arl1 knockdown inhibited STxB transport compared with control cells. Arfaptin-1 overexpression, but not an Arl1 binding-defective mutant (arfaptin-1b-F317A), consistently inhibited STxB transport. Exogenous arfaptin-1 expression did not interfere with the localization of the Arl1-interacting proteins golgin-97 and golgin-245 to the TGN and vice versa. Moreover, we found that the N-terminal region of arfaptin-1 was involved in the regulation of retrograde transport. Our results show that arfaptin-1 acts as a negative regulator in Arl1-mediated retrograde transport and suggest that different functional complexes containing Arl1 form in distinct microdomains and are responsible for different functions.
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Affiliation(s)
- Lien-Hung Huang
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Wei-Chung Lee
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Shu-Ting You
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chia-Chen Cheng
- Department of Cell and Molecular Biology, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Chia-Jung Yu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
- Department of Cell and Molecular Biology, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
- Molecular Medicine Research Center, Chang Gung University, Tao-Yuan, Taiwan
- * E-mail:
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212
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Structural basis for membrane binding and remodeling by the exomer secretory vesicle cargo adaptor. Dev Cell 2014; 30:610-24. [PMID: 25203211 DOI: 10.1016/j.devcel.2014.07.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 04/29/2014] [Accepted: 07/15/2014] [Indexed: 12/21/2022]
Abstract
Cargo adaptor subunits of vesicle coat protein complexes sort transmembrane proteins to distinct membrane compartments in eukaryotic cells. The exomer complex is the only cargo adaptor known to sort proteins at the trans-Golgi network into secretory vesicles. Exomer function is regulated by the Arf1 GTPase, a master regulator of trafficking at the Golgi. We report the structure of exomer bound to two copies of Arf1. Exomer interacts with each Arf1 molecule via two surfaces, one of which is a noncanonical interface that regulates GTP hydrolysis. The structure uncovers an unexpected membrane-proximal hydrophobic element that exomer uses in cooperation with Arf1 to remodel membranes. Given the constrained motion of the exomer hinge region, we envision that exomer dynamically positions multiple membrane insertion elements to drive membrane fission. In contrast to other known cargo adaptors, exomer therefore couples two functions, cargo sorting and membrane fission, into a single complex.
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213
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Affiliation(s)
- Yusong Guo
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, California 94720-3200;
| | - Daniel W. Sirkis
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, California 94720-3200;
| | - Randy Schekman
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, California 94720-3200;
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214
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K33-Linked Polyubiquitination of Coronin 7 by Cul3-KLHL20 Ubiquitin E3 Ligase Regulates Protein Trafficking. Mol Cell 2014; 54:586-600. [DOI: 10.1016/j.molcel.2014.03.035] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 01/28/2014] [Accepted: 03/18/2014] [Indexed: 01/05/2023]
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215
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A complex comprising phosphatidylinositol 4-kinase IIIβ, ACBD3, and Aichi virus proteins enhances phosphatidylinositol 4-phosphate synthesis and is critical for formation of the viral replication complex. J Virol 2014; 88:6586-98. [PMID: 24672044 DOI: 10.1128/jvi.00208-14] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Phosphatidylinositol 4-kinase IIIβ (PI4KB) is a host factor required for the replication of certain picornavirus genomes. We previously showed that nonstructural proteins 2B, 2BC, 2C, 3A, and 3AB of Aichi virus (AiV), a picornavirus, interact with the Golgi protein, acyl-coenzyme A binding domain containing 3 (ACBD3), which interacts with PI4KB. These five viral proteins, ACBD3, PI4KB, and the PI4KB product phosphatidylinositol 4-phosphate (PI4P) colocalize to the AiV RNA replication sites (J. Sasaki et al., EMBO J. 31:754-766, 2012). We here examined the roles of these viral and cellular molecules in the formation of AiV replication complexes. Immunofluorescence microscopy revealed that treatment of AiV polyprotein-expressing cells with a small interfering RNA targeting ACBD3 abolished colocalization of the viral 2B, 2C, and 3A proteins with PI4KB. A PI4KB-specific inhibitor also prevented their colocalization. Virus RNA replication increased the level of cellular PI4P without affecting that of PI4KB, and individual expression of 2B, 2BC, 2C, 3A, or 3AB stimulated PI4P generation. These results suggest that the viral protein/ACBD3/PI4KB complex plays an important role in forming the functional replication complex by enhancing PI4P synthesis. Of the viral proteins, 3A and 3AB were shown to stimulate the in vitro kinase activity of PI4KB through forming a 3A or 3AB/ACBD3/PI4KB complex, whereas the ACBD3-mediated PI4KB activation by 2B and 2C remains to be demonstrated. IMPORTANCE The phosphatidylinositol 4-kinase PI4KB is a host factor required for the replication of certain picornavirus genomes. Aichi virus, a picornavirus belonging to the genus Kobuvirus, forms a complex comprising one of the viral nonstructural proteins 2B, 2BC, 2C, 3A, and 3AB, the Golgi protein ACBD3, and PI4KB to synthesize PI4P at the sites for viral RNA replication. However, the roles of this protein complex in forming the replication complex are unknown. This study showed that virus RNA replication and individual viral proteins enhance the level of cellular PI4P, and suggested that the viral protein/ACBD3/PI4KB complex plays an important role in forming a functional replication complex. Thus, the present study provides a new example of modulation of cellular lipid metabolism by viruses to support the replication of their genomes.
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Abstract
Lipids are unevenly distributed within and between cell membranes, thus defining organelle identity. Such distribution relies on local metabolic branches and mechanisms that move lipids. These processes are regulated by feedback mechanisms that decipher topographical information in organelle membranes and then regulate lipid levels or flows. In the endoplasmic reticulum, the major lipid source, transcriptional regulators and enzymes sense changes in membrane features to modulate lipid production. At the Golgi apparatus, lipid-synthesizing, lipid-flippase, and lipid-transport proteins (LTPs) collaborate to control lipid balance and distribution within the membrane to guarantee remodeling processes crucial for vesicular trafficking. Open questions exist regarding LTPs, which are thought to be lipid sensors that regulate lipid synthesis or carriers that transfer lipids between organelles across long distances or in contact sites. A novel model is that LTPs, by exchanging two different lipids, exploit one lipid gradient between two distinct membranes to build a second lipid gradient.
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Affiliation(s)
- Guillaume Drin
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis and CNRS, 06560 Valbonne, France;
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