1
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Tavares LA, Rodrigues RL, Santos da Costa C, Nascimento JA, Vargas de Carvalho J, Nogueira de Carvalho A, Mardones GA, daSilva LLP. AP-1γ2 is an adaptor protein 1 variant required for endosome-to-Golgi trafficking of the mannose-6-P receptor (CI-MPR) and ATP7B copper transporter. J Biol Chem 2024; 300:105700. [PMID: 38307383 PMCID: PMC10909764 DOI: 10.1016/j.jbc.2024.105700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 01/18/2024] [Accepted: 01/21/2024] [Indexed: 02/04/2024] Open
Abstract
Selective retrograde transport from endosomes back to the trans-Golgi network (TGN) is important for maintaining protein homeostasis, recycling receptors, and returning molecules that were transported to the wrong compartments. Two important transmembrane proteins directed to this pathway are the Cation-Independent Mannose-6-phosphate receptor (CI-MPR) and the ATP7B copper transporter. Among CI-MPR functions is the delivery of acid hydrolases to lysosomes, while ATP7B facilitates the transport of cytosolic copper ions into organelles or the extracellular space. Precise subcellular localization of CI-MPR and ATP7B is essential for the proper functioning of these proteins. This study shows that both CI-MPR and ATP7B interact with a variant of the clathrin adaptor 1 (AP-1) complex that contains a specific isoform of the γ-adaptin subunit called γ2. Through synchronized anterograde trafficking and cell-surface uptake assays, we demonstrated that AP-1γ2 is dispensable for ATP7B and CI-MPR exit from the TGN while being critically required for ATP7B and CI-MPR retrieval from endosomes to the TGN. Moreover, AP-1γ2 depletion leads to the retention of endocytosed CI-MPR in endosomes enriched in retromer complex subunits. These data underscore the importance of AP-1γ2 as a key component in the sorting and trafficking machinery of CI-MPR and ATP7B, highlighting its essential role in the transport of proteins from endosomes.
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Affiliation(s)
- Lucas Alves Tavares
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Roger Luiz Rodrigues
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Cristina Santos da Costa
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Jonas Alburqueque Nascimento
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Julianne Vargas de Carvalho
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Andreia Nogueira de Carvalho
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Gonzalo A Mardones
- Escuela de Medicina, Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia, Chile
| | - Luis L P daSilva
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.
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2
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Krishnan S, Klingauf J. The readily retrievable pool of synaptic vesicles. Biol Chem 2023; 404:385-397. [PMID: 36867726 DOI: 10.1515/hsz-2022-0298] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 02/16/2023] [Indexed: 03/05/2023]
Abstract
In the CNS communication between neurons occurs at synapses by secretion of neurotransmitter via exocytosis of synaptic vesicles (SVs) at the active zone. Given the limited number of SVs in presynaptic boutons a fast and efficient recycling of exocytosed membrane and proteins by triggered compensatory endocytosis is required to maintain neurotransmission. Thus, pre-synapses feature a unique tight coupling of exo- and endocytosis in time and space resulting in the reformation of SVs with uniform morphology and well-defined molecular composition. This rapid response requires early stages of endocytosis at the peri-active zone to be well choreographed to ensure reformation of SVs with high fidelity. The pre-synapse can address this challenge by a specialized membrane microcompartment, where a pre-sorted and pre-assembled readily retrievable pool (RRetP) of endocytic membrane patches is formed, consisting of the vesicle cargo, presumably bound within a nucleated Clathrin and adaptor complex. This review considers evidence for the RRetP microcompartment to be the primary organizer of presynaptic triggered compensatory endocytosis.
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Affiliation(s)
- Sai Krishnan
- Institute of Medical Physics and Biophysics, University of Münster, Robert-Koch Strasse 31, D-48149, Münster, Germany
| | - Jürgen Klingauf
- Institute of Medical Physics and Biophysics, University of Münster, Robert-Koch Strasse 31, D-48149, Münster, Germany.,Center for Soft Nanoscience, Busso-Peus Strasse 10, D-48149, Münster, Germany
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3
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Buser DP, Spang A. Protein sorting from endosomes to the TGN. Front Cell Dev Biol 2023; 11:1140605. [PMID: 36895788 PMCID: PMC9988951 DOI: 10.3389/fcell.2023.1140605] [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: 01/09/2023] [Accepted: 02/09/2023] [Indexed: 02/23/2023] Open
Abstract
Retrograde transport from endosomes to the trans-Golgi network is essential for recycling of protein and lipid cargoes to counterbalance anterograde membrane traffic. Protein cargo subjected to retrograde traffic include lysosomal acid-hydrolase receptors, SNARE proteins, processing enzymes, nutrient transporters, a variety of other transmembrane proteins, and some extracellular non-host proteins such as viral, plant, and bacterial toxins. Efficient delivery of these protein cargo molecules depends on sorting machineries selectively recognizing and concentrating them for their directed retrograde transport from endosomal compartments. In this review, we outline the different retrograde transport pathways governed by various sorting machineries involved in endosome-to-TGN transport. In addition, we discuss how this transport route can be analyzed experimentally.
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Affiliation(s)
| | - Anne Spang
- Biozentrum, University of Basel, Basel, Switzerland
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4
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Duncan MC. New directions for the clathrin adaptor AP-1 in cell biology and human disease. Curr Opin Cell Biol 2022; 76:102079. [DOI: 10.1016/j.ceb.2022.102079] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/02/2022] [Accepted: 03/03/2022] [Indexed: 11/03/2022]
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5
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Schor S, Pu S, Nicolaescu V, Azari S, Kõivomägi M, Karim M, Cassonnet P, Saul S, Neveu G, Yueh A, Demeret C, Skotheim JM, Jacob Y, Randall G, Einav S. The cargo adapter protein CLINT1 is phosphorylated by the Numb-associated kinase BIKE and mediates dengue virus infection. J Biol Chem 2022; 298:101956. [PMID: 35452674 PMCID: PMC9133654 DOI: 10.1016/j.jbc.2022.101956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 03/22/2022] [Accepted: 03/24/2022] [Indexed: 11/25/2022] Open
Abstract
The signaling pathways and cellular functions regulated by the four Numb-associated kinases are largely unknown. We reported that AAK1 and GAK control intracellular trafficking of RNA viruses and revealed a requirement for BIKE in early and late stages of dengue virus (DENV) infection. However, the downstream targets phosphorylated by BIKE have not yet been identified. Here, to identify BIKE substrates, we conducted a barcode fusion genetics-yeast two-hybrid screen and retrieved publicly available data generated via affinity-purification mass spectrometry. We subsequently validated 19 of 47 putative BIKE interactors using mammalian cell-based protein-protein interaction assays. We found that CLINT1, a cargo-specific adapter implicated in bidirectional Golgi-to-endosome trafficking, emerged as a predominant hit in both screens. Our experiments indicated that BIKE catalyzes phosphorylation of a threonine 294 CLINT1 residue both in vitro and in cell culture. Our findings revealed that CLINT1 phosphorylation mediates its binding to the DENV nonstructural 3 protein and subsequently promotes DENV assembly and egress. Additionally, using live-cell imaging we revealed that CLINT1 cotraffics with DENV particles and is involved in mediating BIKE's role in DENV infection. Finally, our data suggest that additional cellular BIKE interactors implicated in the host immune and stress responses and the ubiquitin proteasome system might also be candidate phosphorylation substrates of BIKE. In conclusion, these findings reveal cellular substrates and pathways regulated by the understudied Numb-associated kinase enzyme BIKE, a mechanism for CLINT1 regulation, and control of DENV infection via BIKE signaling, with potential implications for cell biology, virology, and host-targeted antiviral design.
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Affiliation(s)
- Stanford Schor
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA
| | - Szuyuan Pu
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA
| | - Vlad Nicolaescu
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | - Siavash Azari
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA
| | | | - Marwah Karim
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA
| | - Patricia Cassonnet
- Department of Virology, Molecular Genetics of RNA Virus Genetics (GMVR), Pasteur Institute, National Center for Scientific Research, and Paris Diderot University, Paris, France
| | - Sirle Saul
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA
| | - Gregory Neveu
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA
| | - Andrew Yueh
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Zhunan, Taiwan
| | - Caroline Demeret
- Department of Virology, Molecular Genetics of RNA Virus Genetics (GMVR), Pasteur Institute, National Center for Scientific Research, and Paris Diderot University, Paris, France
| | - Jan M Skotheim
- Department of Biology, Stanford University, California, USA
| | - Yves Jacob
- Department of Virology, Molecular Genetics of RNA Virus Genetics (GMVR), Pasteur Institute, National Center for Scientific Research, and Paris Diderot University, Paris, France
| | - Glenn Randall
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | - Shirit Einav
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA; Chan Zuckerberg Biohub, San Francisco, California, USA.
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6
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Buser DP, Bader G, Spiess M. Retrograde transport of CDMPR depends on several machineries as analyzed by sulfatable nanobodies. Life Sci Alliance 2022; 5:5/7/e202101269. [PMID: 35314489 PMCID: PMC8961009 DOI: 10.26508/lsa.202101269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 03/08/2022] [Accepted: 03/09/2022] [Indexed: 11/24/2022] Open
Abstract
Nanobody toolkit enables the quantitative analysis of endosome-to-TGN transport of the mannose-6-phosphate receptor in cells depleted of retrograde transport machineries Retrograde protein transport from the cell surface and endosomes to the TGN is essential for membrane homeostasis in general and for the recycling of mannose-6-phosphate receptors (MPRs) for sorting of lysosomal hydrolases in particular. We used a nanobody-based sulfation tool to more directly determine transport kinetics from the plasma membrane to the TGN for the cation-dependent MPR (CDMPR) with and without rapid or gradual inactivation of candidate machinery proteins. Although knockdown of retromer (Vps26), epsinR, or Rab9a reduced CDMPR arrival to the TGN, no effect was observed upon silencing of TIP47. Strikingly, when retrograde transport was analyzed by rapamycin-induced rapid depletion (knocksideways) or long-term depletion by knockdown of the clathrin adaptor AP-1 or of the GGA machinery, distinct phenotypes in sulfation kinetics were observed, suggesting a potential role of GGA adaptors in retrograde and anterograde transport. Our study illustrates the usefulness of derivatized, sulfation-competent nanobodies, reveals novel insights into CDMPR trafficking biology, and further outlines that the selection of machinery inactivation is critical for phenotype analysis.
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Affiliation(s)
| | - Gaétan Bader
- Biozentrum, University of Basel, Basel, Switzerland
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7
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SNARE proteins: zip codes in vesicle targeting? Biochem J 2022; 479:273-288. [PMID: 35119456 PMCID: PMC8883487 DOI: 10.1042/bcj20210719] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 12/01/2021] [Accepted: 12/22/2021] [Indexed: 12/17/2022]
Abstract
Membrane traffic in eukaryotic cells is mediated by transport vesicles that bud from a precursor compartment and are transported to their destination compartment where they dock and fuse. To reach their intracellular destination, transport vesicles contain targeting signals such as Rab GTPases and polyphosphoinositides that are recognized by tethering factors in the cytoplasm and that connect the vesicles with their respective destination compartment. The final step, membrane fusion, is mediated by SNARE proteins. SNAREs are connected to targeting signals and tethering factors by multiple interactions. However, it is still debated whether SNAREs only function downstream of targeting and tethering or whether they also participate in regulating targeting specificity. Here, we review the evidence and discuss recent data supporting a role of SNARE proteins as targeting signals in vesicle traffic.
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8
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Lujan P, Campelo F. Should I stay or should I go? Golgi membrane spatial organization for protein sorting and retention. Arch Biochem Biophys 2021; 707:108921. [PMID: 34038703 DOI: 10.1016/j.abb.2021.108921] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/12/2021] [Accepted: 05/03/2021] [Indexed: 12/23/2022]
Abstract
The Golgi complex is the membrane-bound organelle that lies at the center of the secretory pathway. Its main functions are to maintain cellular lipid homeostasis, to orchestrate protein processing and maturation, and to mediate protein sorting and export. These functions are not independent of one another, and they all require that the membranes of the Golgi complex have a well-defined biochemical composition. Importantly, a finely-regulated spatiotemporal organization of the Golgi membrane components is essential for the correct performance of the organelle. In here, we review our current mechanistic and molecular understanding of how Golgi membranes are spatially organized in the lateral and axial directions to fulfill their functions. In particular, we highlight the current evidence and proposed models of intra-Golgi transport, as well as the known mechanisms for the retention of Golgi residents and for the sorting and export of transmembrane cargo proteins. Despite the controversies, conflicting evidence, clashes between models, and technical limitations, the field has moved forward and we have gained extensive knowledge in this fascinating topic. However, there are still many important questions that remain to be completely answered. We hope that this review will help boost future investigations on these issues.
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Affiliation(s)
- Pablo Lujan
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Barcelona, Spain.
| | - Felix Campelo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Barcelona, Spain.
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9
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Zhou Y, Zhao R, Schwarz EC, Akbar R, Kaba M, Pattu V, Helms V, Rieger H, Nunes-Hasler P, Qu B. Interorganelle Tethering to Endocytic Organelles Determines Directional Cytokine Transport in CD4 + T Cells. THE JOURNAL OF IMMUNOLOGY 2020; 205:2988-3000. [PMID: 33106338 DOI: 10.4049/jimmunol.2000195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 09/20/2020] [Indexed: 12/24/2022]
Abstract
Delivery of vesicles to their desired destinations plays a central role in maintaining proper cell functionality. In certain scenarios, depending on loaded cargos, the vesicles have spatially distinct destinations. For example, in T cells, some cytokines (e.g., IL-2) are polarized to the T cell-target cell interface, whereas the other cytokines are delivered multidirectionally (e.g., TNF-α). In this study, we show that in primary human CD4+ T cells, both TNF-α+ and IL-2+ vesicles can tether with endocytic organelles (lysosomes/late endosomes) by forming membrane contact sites. Tethered cytokine-containing vesicle (CytV)-endocytic organelle pairs are released sequentially. Only endocytic organelle-tethered CytVs are preferentially transported to their desired destination. Mathematical models suggest that endocytic organelle tethering could regulate the direction of cytokine transport by selectively attaching different microtubule motor proteins (such as kinesin and dynein) to the corresponding CytVs. These findings establish the previously unknown interorganelle tethering to endocytic organelles as a universal solution for directional cytokine transport in CD4+ T cells. Modulating tethering to endocytic organelles can, therefore, coordinately control directionally distinct cytokine transport.
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Affiliation(s)
- Yan Zhou
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, 66421 Homburg, Germany
| | - Renping Zhao
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, 66421 Homburg, Germany
| | - Eva C Schwarz
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, 66421 Homburg, Germany
| | - Rahmad Akbar
- Center for Bioinformatics, Saarland University, 66123 Saarbrücken, Germany
| | - Mayis Kaba
- Department of Cell Physiology and Metabolism, University Medical Center, University of Geneva, 1211 Geneva, Switzerland
| | - Varsha Pattu
- Department of Physiology, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, 66421 Homburg, Germany
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, 66123 Saarbrücken, Germany
| | - Heiko Rieger
- Department of Theoretical Physics, Saarland University, 66123 Saarbrücken, Germany
| | - Paula Nunes-Hasler
- Department of Cell Physiology and Metabolism, University Medical Center, University of Geneva, 1211 Geneva, Switzerland.,Department of Pathology and Immunology, University Medical Center, University of Geneva, 1211 Geneva, Switzerland; and
| | - Bin Qu
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, 66421 Homburg, Germany; .,Leibniz Institute for New Materials, 66123 Saarbrücken, Germany
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10
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Margiotta A, Frei DM, Sendstad IH, Janssen L, Neefjes J, Bakke O. Invariant chain regulates endosomal fusion and maturation through an interaction with the SNARE Vti1b. J Cell Sci 2020; 133:jcs244624. [PMID: 32907852 DOI: 10.1242/jcs.244624] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 08/25/2020] [Indexed: 01/01/2023] Open
Abstract
The invariant chain (Ii, also known as CD74) is a multifunctional regulator of adaptive immune responses and is responsible for sorting major histocompatibility complex class I and class II (MHCI and MHCII, respectively) molecules, as well as other Ii-associated molecules, to a specific endosomal pathway. When Ii is expressed, endosomal maturation and proteolytic degradation of proteins are delayed and, in non-antigen presenting cells, the endosomal size increases, but the molecular mechanisms underlying this are not known. We identified that a SNARE, Vti1b, is essential for regulating these Ii-induced effects. Vti1b binds to Ii and is localized at the contact sites of fusing Ii-positive endosomes. Furthermore, truncated Ii lacking the cytoplasmic tail, which is not internalized from the plasma membrane, relocates Vti1b to the plasma membrane. Knockout of Ii in an antigen-presenting cell line was found to speed up endosomal maturation, whereas silencing of Vti1b inhibits the Ii-induced maturation delay. Our results suggest that Ii, by interacting with the SNARE Vti1b in antigen-presenting cells, directs specific Ii-associated SNARE-mediated fusion in the early part of the endosomal pathway that leads to a slower endosomal maturation for efficient antigen processing and MHC antigen loading.
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Affiliation(s)
- Azzurra Margiotta
- Department of Molecular Biosciences, University of Oslo, PB 1066, 0316 Oslo, Norway
| | - Dominik M Frei
- Department of Molecular Biosciences, University of Oslo, PB 1066, 0316 Oslo, Norway
| | | | - Lennert Janssen
- Department of Cell and Chemical Biology, Oncode Institute, Leiden University Medical Center LUMC, Leiden, The Netherlands
| | - Jacques Neefjes
- Department of Cell and Chemical Biology, Oncode Institute, Leiden University Medical Center LUMC, Leiden, The Netherlands
| | - Oddmund Bakke
- Department of Molecular Biosciences, University of Oslo, PB 1066, 0316 Oslo, Norway
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11
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Tu Y, Zhao L, Billadeau DD, Jia D. Endosome-to-TGN Trafficking: Organelle-Vesicle and Organelle-Organelle Interactions. Front Cell Dev Biol 2020; 8:163. [PMID: 32258039 PMCID: PMC7093645 DOI: 10.3389/fcell.2020.00163] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Accepted: 02/28/2020] [Indexed: 12/13/2022] Open
Abstract
Retrograde transport from endosomes to the trans-Golgi network (TGN) diverts proteins and lipids away from lysosomal degradation. It is essential for maintaining cellular homeostasis and signaling. In recent years, significant advancements have been made in understanding this classical pathway, revealing new insights into multiple steps of vesicular trafficking as well as critical roles of ER-endosome contacts for endosomal trafficking. In this review, we summarize up-to-date knowledge about this trafficking pathway, in particular, mechanisms of cargo recognition at endosomes and vesicle tethering at the TGN, and contributions of ER-endosome contacts.
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Affiliation(s)
- Yingfeng Tu
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, State Key Laboratory of Biotherapy, Department of Paediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Lin Zhao
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, State Key Laboratory of Biotherapy, Department of Paediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Daniel D. Billadeau
- Division of Oncology Research, Schulze Center for Novel Therapeutics, Mayo Clinic, Rochester, MN, United States
| | - Da Jia
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, State Key Laboratory of Biotherapy, Department of Paediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
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12
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A formal methods approach to predicting new features of the eukaryotic vesicle traffic system. ACTA INFORM 2019. [DOI: 10.1007/s00236-019-00357-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Emperador-Melero J, Toonen RF, Verhage M. Vti Proteins: Beyond Endolysosomal Trafficking. Neuroscience 2019; 420:32-40. [DOI: 10.1016/j.neuroscience.2018.11.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 11/08/2018] [Accepted: 11/09/2018] [Indexed: 10/27/2022]
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14
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Huang Y, Ma T, Lau PK, Wang J, Zhao T, Du S, Loy MMT, Guo Y. Visualization of Protein Sorting at the Trans-Golgi Network and Endosomes Through Super-Resolution Imaging. Front Cell Dev Biol 2019; 7:181. [PMID: 31552246 PMCID: PMC6733968 DOI: 10.3389/fcell.2019.00181] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 08/19/2019] [Indexed: 12/19/2022] Open
Abstract
The trans-Golgi network (TGN) and endosomes are essential protein sorting stations in the secretory transport pathway. Protein sorting is fundamentally a process of spatial segregation, but the spatial relationships among the proteins that constitute the sorting machinery have not been systematically analyzed at high resolution in mammalian cells. Here, using two-color STORM imaging, we show that the TGN/endosome-localized cargo adaptors, AP-1, GGA2 and epsinR, form elongated structures of over 250 nm in length at the juxta-nuclear Golgi area. Many of these structures are associated with clathrin. We found that AP-1 is spatially segregated from AP-3 and GGA2, whereas a fraction of AP-1 and GGA2 punctae are associated with epsinR. Moreover, we observed that the planar cell polarity cargo proteins, Vangl2 and Frizzled6 associate with different cargo adaptors—AP-1 and GGA2 or epsinR, respectively—when exiting the TGN. Knockdown analysis confirms the functional significance of this segregation. Our data indicates that TGN/endosome-localized cargo adaptors have distinct spatial relationships. The spatially segregated cargo adaptors GGA2 and AP-1 regulate sorting of Frizzled6 and Vangl2, respectively and spatially associated cargo adaptors can cooperatively regulate a specific sorting process.
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Affiliation(s)
- Yan Huang
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China
| | - Tianji Ma
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China
| | - Pik Ki Lau
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China
| | - Jinhui Wang
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China
| | - Teng Zhao
- Light Innovation Technology Limited, Hong Kong, China
| | - Shengwang Du
- Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology, Hong Kong, China.,Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Michael M T Loy
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Yusong Guo
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China.,Hong Kong University of Science and Technology Shenzhen Research Institute, Shenzhen, China
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15
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Yanguas F, Moscoso-Romero E, Valdivieso MH. Ent3 and GGA adaptors facilitate diverse anterograde and retrograde trafficking events to and from the prevacuolar endosome. Sci Rep 2019; 9:10747. [PMID: 31341193 PMCID: PMC6656748 DOI: 10.1038/s41598-019-47035-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 07/09/2019] [Indexed: 11/09/2022] Open
Abstract
Carboxypeptidases Y (Cpy1) and S (Cps1), the receptor Vps10, and the ATPase subunit Vph1 follow the carboxypeptidase Y (CPY) pathway from the trans-Golgi network (TGN) to the prevacuolar endosome (PVE). Using Schizosaccharomyces pombe quantitative live-cell imaging, biochemical and genetic analyses, we extended the previous knowledge and showed that collaboration between Gga22, the dominant Golgi-localized Gamma-ear-containing ARF-binding (GGA) protein, and Gga21, and between Gga22 and the endosomal epsin Ent3, was required for efficient: i) Vps10 anterograde trafficking from the TGN to the PVE; ii) Vps10 retrograde trafficking from the PVE to the TGN; iii) Cps1 exit from the TGN, and its sorting in the PVE en route to the vacuole; and iv) Syb1/Snc1 recycling to the plasma membrane through the PVE. Therefore, monomeric clathrin adaptors facilitated the trafficking of Vps10 in both directions of the CPY pathway, and facilitated trafficking events of Cps1 in different organelles. By contrast, they were dispensable for Vph1 trafficking. Thus, these adaptors regulated the traffic of some, but not all, of the cargo of the CPY pathway, and regulated the traffic of cargoes that do not follow this pathway. Additionally, this collaboration was required for PVE organization and efficient growth under stress.
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Affiliation(s)
- Francisco Yanguas
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain.,Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas (CSIC), Calle Zacarías González 2, 37007, Salamanca, Spain
| | - Esteban Moscoso-Romero
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain.,Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas (CSIC), Calle Zacarías González 2, 37007, Salamanca, Spain
| | - M-Henar Valdivieso
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain. .,Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas (CSIC), Calle Zacarías González 2, 37007, Salamanca, Spain.
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16
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Abstract
The entry of pathogens into nonphagocytic host cells has received much attention in the past three decades, revealing a vast array of strategies employed by bacteria and viruses. A method of internalization that has been extensively studied in the context of viral infections is the use of the clathrin-mediated pathway. More recently, a role for clathrin in the entry of some intracellular bacterial pathogens was discovered. Classically, clathrin-mediated endocytosis was thought to accommodate internalization only of particles smaller than 150 nm; however, this was challenged upon the discovery that Listeria monocytogenes requires clathrin to enter eukaryotic cells. Now, with discoveries that clathrin is required during other stages of some bacterial infections, another paradigm shift is occurring. There is a more diverse impact of clathrin during infection than previously thought. Much of the recent data describing clathrin utilization in processes such as bacterial attachment, cell-to-cell spread and intracellular growth may be due to newly discovered divergent roles of clathrin in the cell. Not only does clathrin act to facilitate endocytosis from the plasma membrane, but it also participates in budding from endosomes and the Golgi apparatus and in mitosis. Here, the manipulation of clathrin processes by bacterial pathogens, including its traditional role during invasion and alternative ways in which clathrin supports bacterial infection, is discussed. Researching clathrin in the context of bacterial infections will reveal new insights that inform our understanding of host-pathogen interactions and allow researchers to fully appreciate the diverse roles of clathrin in the eukaryotic cell.
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17
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A versatile nanobody-based toolkit to analyze retrograde transport from the cell surface. Proc Natl Acad Sci U S A 2018; 115:E6227-E6236. [PMID: 29915061 DOI: 10.1073/pnas.1801865115] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Retrograde transport of membranes and proteins from the cell surface to the Golgi and beyond is essential to maintain homeostasis, compartment identity, and physiological functions. To study retrograde traffic biochemically, by live-cell imaging or by electron microscopy, we engineered functionalized anti-GFP nanobodies (camelid VHH antibody domains) to be bacterially expressed and purified. Tyrosine sulfation consensus sequences were fused to the nanobody for biochemical detection of trans-Golgi arrival, fluorophores for fluorescence microscopy and live imaging, and APEX2 (ascorbate peroxidase 2) for electron microscopy and compartment ablation. These functionalized nanobodies are specifically captured by GFP-modified reporter proteins at the cell surface and transported piggyback to the reporters' homing compartments. As an application of this tool, we have used it to determine the contribution of adaptor protein-1/clathrin in retrograde transport kinetics of the mannose-6-phosphate receptors from endosomes back to the trans-Golgi network. Our experiments establish functionalized nanobodies as a powerful tool to demonstrate and quantify retrograde transport pathways.
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18
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Takatori S, Tomita T. AP180 N-Terminal Homology (ANTH) and Epsin N-Terminal Homology (ENTH) Domains: Physiological Functions and Involvement in Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1111:55-76. [DOI: 10.1007/5584_2018_218] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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19
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Ma T, Li B, Wang R, Lau PK, Huang Y, Jiang L, Schekman R, Guo Y. A mechanism for differential sorting of the planar cell polarity proteins Frizzled6 and Vangl2 at the trans-Golgi network. J Biol Chem 2018; 293:8410-8427. [PMID: 29666182 DOI: 10.1074/jbc.ra118.001906] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 03/12/2018] [Indexed: 01/14/2023] Open
Abstract
In planar cell polarity (PCP), the epithelial cells are polarized along the plane of the cell surface perpendicular to the classical apical-basal axis, a process mediated by several conserved signaling receptors. Two PCP-signaling proteins, VANGL planar cell polarity protein 2 (Vangl2) and Frizzled6 (Fzd6), are located asymmetrically on opposite boundaries of the cell. Examining sorting of these two proteins at the trans-Golgi network (TGN), we demonstrated previously that the GTP-binding protein ADP-ribosylation factor-related protein 1 (Arfrp1) and the clathrin-associated adaptor protein complex 1 (AP-1) are required for Vangl2 transport from the TGN. In contrast, TGN export of Frizzled6 does not depend on Arfrp1 or AP-1. Here, to further investigate the TGN sorting process in mammalian cells, we reconstituted release of Vangl2 and Frizzled6 from the TGN into vesicles in vitro Immunoblotting of released vesicles indicated that Vangl2 and Frizzled6 exit the TGN in separate compartments. Knockdown analysis revealed that a clathrin adaptor, epsinR, regulates TGN export of Frizzled6 but not of Vangl2. Protein interaction analysis suggested that epsinR forms a stable complex with clathrin and that this complex interacts with a conserved polybasic motif in the Frizzled6 cytosolic domain to package Frizzled6 into transport vesicles. Moreover, we found that Frizzled6-epsinR binding dissociates epsinR from AP-1, which may separate these two cargo adaptors from each other to perform distinct cargo-sorting functions. Our results suggest that Vangl2 and Frizzled6 are packaged into separate vesicles that are regulated by different clathrin adaptors at the TGN, which may contribute to their asymmetric localizations.
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Affiliation(s)
- Tianji Ma
- From the Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Baiying Li
- the Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Ryan Wang
- the Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, and
| | - Pik Ki Lau
- From the Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Yan Huang
- From the Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Liwen Jiang
- the Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Randy Schekman
- the Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, and
| | - Yusong Guo
- From the Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China,
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20
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Dannhauser PN, Camus SM, Sakamoto K, Sadacca LA, Torres JA, Camus MD, Briant K, Vassilopoulos S, Rothnie A, Smith CJ, Brodsky FM. CHC22 and CHC17 clathrins have distinct biochemical properties and display differential regulation and function. J Biol Chem 2017; 292:20834-20844. [PMID: 29097553 PMCID: PMC5743061 DOI: 10.1074/jbc.m117.816256] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 10/30/2017] [Indexed: 11/06/2022] Open
Abstract
Clathrins are cytoplasmic proteins that play essential roles in endocytosis and other membrane traffic pathways. Upon recruitment to intracellular membranes, the canonical clathrin triskelion assembles into a polyhedral protein coat that facilitates vesicle formation and captures cargo molecules for transport. The triskelion is formed by trimerization of three clathrin heavy-chain subunits. Most vertebrates have two isoforms of clathrin heavy chains, CHC17 and CHC22, generating two clathrins with distinct cellular functions. CHC17 forms vesicles at the plasma membrane for receptor-mediated endocytosis and at the trans-Golgi network for organelle biogenesis. CHC22 plays a key role in intracellular targeting of the insulin-regulated glucose transporter 4 (GLUT4), accumulates at the site of GLUT4 sequestration during insulin resistance, and has also been implicated in neuronal development. Here, we demonstrate that CHC22 and CHC17 share morphological features, in that CHC22 forms a triskelion and latticed vesicle coats. However, cellular CHC22-coated vesicles were distinct from those formed by CHC17. The CHC22 coat was more stable to pH change and was not removed by the enzyme complex that disassembles the CHC17 coat. Moreover, the two clathrins were differentially recruited to membranes by adaptors, and CHC22 did not support vesicle formation or transferrin endocytosis at the plasma membrane in the presence or absence of CHC17. Our findings provide biochemical evidence for separate regulation and distinct functional niches for CHC17 and CHC22 in human cells. Furthermore, the greater stability of the CHC22 coat relative to the CHC17 coat may be relevant to its excessive accumulation with GLUT4 during insulin resistance.
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Affiliation(s)
- Philip N Dannhauser
- From the Division of Biosciences, University College London, London WC1E 6BT, United Kingdom.,the Institute of Cell Biology/Electron Microscopy, Centre of Anatomy, Hanover Medical School, 30625 Hanover, Germany
| | - Stéphane M Camus
- From the Division of Biosciences, University College London, London WC1E 6BT, United Kingdom.,the Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, Microbiology and Immunology and The G.W. Hooper Foundation, University of California at San Francisco, San Francisco, California 94143
| | - Kazuho Sakamoto
- the Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, Microbiology and Immunology and The G.W. Hooper Foundation, University of California at San Francisco, San Francisco, California 94143.,the Department of Pharmacology, Fukushima Medical University School of Medicine, Fukushima, Fukushima 960-1295, Japan
| | - L Amanda Sadacca
- From the Division of Biosciences, University College London, London WC1E 6BT, United Kingdom
| | - Jorge A Torres
- the Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, Microbiology and Immunology and The G.W. Hooper Foundation, University of California at San Francisco, San Francisco, California 94143
| | - Marine D Camus
- From the Division of Biosciences, University College London, London WC1E 6BT, United Kingdom.,the Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, Microbiology and Immunology and The G.W. Hooper Foundation, University of California at San Francisco, San Francisco, California 94143
| | - Kit Briant
- From the Division of Biosciences, University College London, London WC1E 6BT, United Kingdom
| | - Stéphane Vassilopoulos
- the Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, Microbiology and Immunology and The G.W. Hooper Foundation, University of California at San Francisco, San Francisco, California 94143.,the Institut de Myologie, Paris F-75013, France
| | - Alice Rothnie
- Life & Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, United Kingdom, and
| | - Corinne J Smith
- the Department of Biological Sciences, Warwick University, Coventry CV4 7AL, United Kingdom
| | - Frances M Brodsky
- From the Division of Biosciences, University College London, London WC1E 6BT, United Kingdom, .,the Departments of Bioengineering and Therapeutic Sciences, Pharmaceutical Chemistry, Microbiology and Immunology and The G.W. Hooper Foundation, University of California at San Francisco, San Francisco, California 94143
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21
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Archuleta TL, Frazier MN, Monken AE, Kendall AK, Harp J, McCoy AJ, Creanza N, Jackson LP. Structure and evolution of ENTH and VHS/ENTH-like domains in tepsin. Traffic 2017; 18:590-603. [PMID: 28691777 PMCID: PMC5567745 DOI: 10.1111/tra.12499] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 07/02/2017] [Accepted: 07/06/2017] [Indexed: 12/28/2022]
Abstract
Tepsin is currently the only accessory trafficking protein identified in adaptor-related protein 4 (AP4)-coated vesicles originating at the trans-Golgi network (TGN). The molecular basis for interactions between AP4 subunits and motifs in the tepsin C-terminus have been characterized, but the biological role of tepsin remains unknown. We determined X-ray crystal structures of the tepsin epsin N-terminal homology (ENTH) and VHS/ENTH-like domains. Our data reveal unexpected structural features that suggest key functional differences between these and similar domains in other trafficking proteins. The tepsin ENTH domain lacks helix0, helix8 and a lipid binding pocket found in epsin1/2/3. These results explain why tepsin requires AP4 for its membrane recruitment and further suggest ENTH domains cannot be defined solely as lipid binding modules. The VHS domain lacks helix8 and thus contains fewer helices than other VHS domains. Structural data explain biochemical and biophysical evidence that tepsin VHS does not mediate known VHS functions, including recognition of dileucine-based cargo motifs or ubiquitin. Structural comparisons indicate the domains are very similar to each other, and phylogenetic analysis reveals their evolutionary pattern within the domain superfamily. Phylogenetics and comparative genomics further show tepsin within a monophyletic clade that diverged away from epsins early in evolutionary history (~1500 million years ago). Together, these data provide the first detailed molecular view of tepsin and suggest tepsin structure and function diverged away from other epsins. More broadly, these data highlight the challenges inherent in classifying and understanding protein function based only on sequence and structure.
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Affiliation(s)
- Tara L. Archuleta
- Department of Biological Sciences, Vanderbilt University, Nashville,
TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN,
USA
| | - Meredith N. Frazier
- Department of Biological Sciences, Vanderbilt University, Nashville,
TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN,
USA
| | - Anderson E. Monken
- Department of Biological Sciences, Vanderbilt University, Nashville,
TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN,
USA
| | - Amy K. Kendall
- Department of Biological Sciences, Vanderbilt University, Nashville,
TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN,
USA
| | - Joel Harp
- Center for Structural Biology, Vanderbilt University, Nashville, TN,
USA
| | - Airlie J. McCoy
- Cambridge Institute for Medical Research, Department of Clinical
Biochemistry, University of Cambridge, Hills Road, Cambridge, United Kingdom
| | - Nicole Creanza
- Department of Biological Sciences, Vanderbilt University, Nashville,
TN, USA
| | - Lauren P. Jackson
- Department of Biological Sciences, Vanderbilt University, Nashville,
TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN,
USA
- Department of Biochemistry, Vanderbilt University, Nashville, TN,
USA
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22
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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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23
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Staudt C, Gilis F, Boonen M, Jadot M. Molecular determinants that mediate the sorting of human ATG9A from the endoplasmic reticulum. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1863:2299-310. [PMID: 27316455 DOI: 10.1016/j.bbamcr.2016.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 06/07/2016] [Accepted: 06/14/2016] [Indexed: 11/15/2022]
Abstract
ATG9A is a multispanning membrane protein required for autophagosome formation. Under basal conditions, neosynthesized ATG9A proteins travel to the Golgi apparatus and cycle between the trans-Golgi network and endosomes. In the present work, we searched for molecular determinants involved in the subcellular trafficking of human ATG9A in HeLa cells using sequential deletions and point mutations. Deletion of amino acids L(340) to L(354) resulted in the retention of ATG9A in the endoplasmic reticulum. In addition, we found that substitution of the L(711)YM(713) sequence (located in the C-terminal region of ATG9A) by alanine residues severely impaired its transport through the Golgi apparatus. This defect could be corrected by oligomerization of the mutant protein with co-transfected wild-type ATG9A, suggesting that ATG9A oligomerization may help its sorting through biosynthetic compartments. Lastly, the study of the consequences of the LYM/AAA mutation on the intracellular trafficking of ATG9A highlighted that some newly synthesized ATG9A can bypass the Golgi apparatus to reach the plasma membrane. Taken together, these findings provide new insights into the intracellular pathways followed by ATG9A to reach different subcellular compartments, and into the intramolecular determinants that drive the sorting of this protein.
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Affiliation(s)
- Catherine Staudt
- URPhyM-Laboratoire de Chimie Physiologique, Université de Namur, Belgium
| | - Florentine Gilis
- URPhyM-Laboratoire de Chimie Physiologique, Université de Namur, Belgium
| | - Marielle Boonen
- URPhyM-Laboratoire de Chimie Physiologique, Université de Namur, Belgium
| | - Michel Jadot
- URPhyM-Laboratoire de Chimie Physiologique, Université de Namur, Belgium.
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24
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Imae R, Dejima K, Kage-Nakadai E, Arai H, Mitani S. Endomembrane-associated RSD-3 is important for RNAi induced by extracellular silencing RNA in both somatic and germ cells of Caenorhabditis elegans. Sci Rep 2016; 6:28198. [PMID: 27306325 PMCID: PMC4910058 DOI: 10.1038/srep28198] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 06/01/2016] [Indexed: 12/25/2022] Open
Abstract
RNA silencing signals in C. elegans spread among cells, leading to RNAi
throughout the body. During systemic spread of RNAi, membrane trafficking is thought
to play important roles. Here, we show that RNAi Spreading Defective-3
(rsd-3), which encodes a homolog of epsinR, a conserved ENTH (epsin
N-terminal homology) domain protein, generally participates in cellular uptake of
silencing RNA. RSD-3 is previously thought to be involved in systemic RNAi only in
germ cells, but we isolated several deletion alleles of rsd-3, and found that
these mutants are defective in the spread of silencing RNA not only into germ cells
but also into somatic cells. RSD-3 is ubiquitously expressed, and intracellularly
localized to the trans-Golgi network (TGN) and endosomes. Tissue-specific
rescue experiments indicate that RSD-3 is required for importing silencing RNA into
cells rather than exporting from cells. Structure/function analysis showed that the
ENTH domain alone is sufficient, and membrane association of the ENTH domain is
required, for RSD-3 function in systemic RNAi. Our results suggest that endomembrane
trafficking through the TGN and endosomes generally plays an important role in
cellular uptake of silencing RNA.
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Affiliation(s)
- Rieko Imae
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Katsufumi Dejima
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Eriko Kage-Nakadai
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Hiroyuki Arai
- Graduate School of Pharmaceutical Science, University of Tokyo, Tokyo, Japan
| | - Shohei Mitani
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan.,Tokyo Women's Medical University Institute for Integrated Medical Sciences, Tokyo, Japan
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25
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Frazier MN, Davies AK, Voehler M, Kendall AK, Borner GHH, Chazin WJ, Robinson MS, Jackson LP. Molecular Basis for the Interaction Between AP4 β4 and its Accessory Protein, Tepsin. Traffic 2016; 17:400-15. [PMID: 26756312 PMCID: PMC4805503 DOI: 10.1111/tra.12375] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 01/07/2016] [Accepted: 01/07/2016] [Indexed: 01/08/2023]
Abstract
The adaptor protein 4 (AP4) complex (ϵ/β4/μ4/σ4 subunits) forms a non-clathrin coat on vesicles departing the trans-Golgi network. AP4 biology remains poorly understood, in stark contrast to the wealth of molecular data available for the related clathrin adaptors AP1 and AP2. AP4 is important for human health because mutations in any AP4 subunit cause severe neurological problems, including intellectual disability and progressive spastic para- or tetraplegias. We have used a range of structural, biochemical and biophysical approaches to determine the molecular basis for how the AP4 β4 C-terminal appendage domain interacts with tepsin, the only known AP4 accessory protein. We show that tepsin harbors a hydrophobic sequence, LFxG[M/L]x[L/V], in its unstructured C-terminus, which binds directly and specifically to the C-terminal β4 appendage domain. Using nuclear magnetic resonance chemical shift mapping, we define the binding site on the β4 appendage by identifying residues on the surface whose signals are perturbed upon titration with tepsin. Point mutations in either the tepsin LFxG[M/L]x[L/V] sequence or in its cognate binding site on β4 abolish in vitro binding. In cells, the same point mutations greatly reduce the amount of tepsin that interacts with AP4. However, they do not abolish the binding between tepsin and AP4 completely, suggesting the existence of additional interaction sites between AP4 and tepsin. These data provide one of the first detailed mechanistic glimpses at AP4 coat assembly and should provide an entry point for probing the role of AP4-coated vesicles in cell biology, and especially in neuronal function.
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Affiliation(s)
- Meredith N Frazier
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Alexandra K Davies
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge, UK
| | - Markus Voehler
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
- Department of Biochemistry and Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Amy K Kendall
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Georg H H Borner
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Walter J Chazin
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
- Department of Biochemistry and Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Margaret S Robinson
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge, UK
| | - Lauren P Jackson
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
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26
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Robinson MS. Forty Years of Clathrin-coated Vesicles. Traffic 2015; 16:1210-38. [PMID: 26403691 DOI: 10.1111/tra.12335] [Citation(s) in RCA: 230] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 09/16/2015] [Accepted: 09/16/2015] [Indexed: 12/11/2022]
Abstract
The purification of coated vesicles and the discovery of clathrin by Barbara Pearse in 1975 was a landmark in cell biology. Over the past 40 years, work from many labs has uncovered the molecular details of clathrin and its associated proteins, including how they assemble into a coated vesicle and how they select cargo. Unexpected connections have been found with signalling, development, neuronal transmission, infection, immunity and genetic disorders. But there are still a number of unanswered questions, including how clathrin-mediated trafficking is regulated and how the machinery evolved.
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Affiliation(s)
- Margaret S Robinson
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
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27
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Hirst J, Edgar JR, Borner GHH, Li S, Sahlender DA, Antrobus R, Robinson MS. Contributions of epsinR and gadkin to clathrin-mediated intracellular trafficking. Mol Biol Cell 2015; 26:3085-103. [PMID: 26179914 PMCID: PMC4551321 DOI: 10.1091/mbc.e15-04-0245] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 07/06/2015] [Indexed: 01/14/2023] Open
Abstract
EpsinR and gadkin are two components of intracellular clathrin-coated vesicles whose precise functions are unclear. Rapid depletion of each protein from the available pool using the knocksideways method strongly inhibited the production of intracellular clathrin-coated vesicles, providing new insights into the functions of both proteins. The precise functions of most of the proteins that participate in clathrin-mediated intracellular trafficking are unknown. We investigated two such proteins, epsinR and gadkin, using the knocksideways method, which rapidly depletes proteins from the available pool by trapping them onto mitochondria. Although epsinR is known to be an N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE)-specific adaptor, the epsinR knocksideways blocked the production of the entire population of intracellular clathrin-coated vesicles (CCVs), suggesting a more global function. Using the epsinR knocksideways data, we were able to estimate the copy number of all major intracellular CCV proteins. Both sides of the vesicle are densely covered, indicating that CCVs sort their cargo by molecular crowding. Trapping of gadkin onto mitochondria also blocked the production of intracellular CCVs but by a different mechanism: vesicles became cross-linked to mitochondria and pulled out toward the cell periphery. Both phenotypes provide new insights into the regulation of intracellular CCV formation, which could not have been found using more conventional approaches.
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Affiliation(s)
- Jennifer Hirst
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - James R Edgar
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Georg H H Borner
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Sam Li
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Daniela A Sahlender
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Robin Antrobus
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Margaret S Robinson
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
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Borner GHH, Fielding AB. Isolation of clathrin-coated vesicles from tissue culture cells. Cold Spring Harb Protoc 2014; 2014:1136-1138. [PMID: 25368317 DOI: 10.1101/pdb.top074435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The study of clathrin-coated vesicles (CCVs) isolated from various organs has revealed the identities and important features of many of the factors involved in membrane trafficking. The development of isolation methods using cultured cell lines has made it possible to manipulate the source material before isolation to ask important questions about the roles of these factors and the pathways in which they are involved. We discuss here the advantages and limitations of the use of cultured cell lines for the isolation of CCVs.
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Affiliation(s)
- Georg H H Borner
- Department of Proteomics and Signal Transduction, Max Plank Institute of Biochemistry, 82152 Martinsried, Germany
| | - Andrew B Fielding
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, United Kingdom
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Borner GHH, Fielding AB. Isolating HeLa cell fractions enriched for clathrin-coated vesicles. Cold Spring Harb Protoc 2014; 2014:1184-7. [PMID: 25368312 DOI: 10.1101/pdb.prot083147] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HeLa cell lines can be experimentally manipulated using drugs or gene-silencing techniques such as RNA interference. Fractions enriched for clathrin-coated vesicles (CCVs) can be isolated from these cell lines and used to study the effects of these manipulations on the composition of CCVs. This protocol, originally developed in the laboratory of Margaret Robinson (Cambridge, United Kingdom), describes the preparation of a HeLa cell fraction that is enriched for a mixed population of CCVs and is suitable for analysis by mass spectroscopy, western blotting, or electron microscopy.
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Affiliation(s)
- Georg H H Borner
- Department of Proteomics and Signal Transduction, Max Plank Institute of Biochemistry, 82152 Martinsried, Germany
| | - Andrew B Fielding
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, United Kingdom
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Shishido T, Hachisuka M, Ryuzaki K, Miura Y, Tanabe A, Tamura Y, Kusayanagi T, Takeuchi T, Kamisuki S, Sugawara F, Sahara H. EpsinR, a target for pyrenocine B, role in endogenous MHC-II-restricted antigen presentation. Eur J Immunol 2014; 44:3220-31. [DOI: 10.1002/eji.201444475] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 07/31/2014] [Accepted: 09/03/2014] [Indexed: 01/28/2023]
Affiliation(s)
- Tatsuya Shishido
- Laboratory of Biology; Azabu University School of Veterinary Medicine; Sagamihara Japan
| | - Masami Hachisuka
- Laboratory of Biology; Azabu University School of Veterinary Medicine; Sagamihara Japan
| | - Kai Ryuzaki
- Laboratory of Biology; Azabu University School of Veterinary Medicine; Sagamihara Japan
| | - Yuko Miura
- Laboratory of Biology; Azabu University School of Veterinary Medicine; Sagamihara Japan
| | - Atsushi Tanabe
- Laboratory of Biology; Azabu University School of Veterinary Medicine; Sagamihara Japan
| | - Yasuaki Tamura
- Department of Pathology; Sapporo Medical University School of Medicine; Sapporo Japan
| | - Tomoe Kusayanagi
- Genome and Drug Research Center; Tokyo University of Science; Chiba Japan
| | - Toshifumi Takeuchi
- Genome and Drug Research Center; Tokyo University of Science; Chiba Japan
| | - Shinji Kamisuki
- Genome and Drug Research Center; Tokyo University of Science; Chiba Japan
| | - Fumio Sugawara
- Genome and Drug Research Center; Tokyo University of Science; Chiba Japan
| | - Hiroeki Sahara
- Laboratory of Biology; Azabu University School of Veterinary Medicine; Sagamihara Japan
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31
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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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Messa M, Fernández-Busnadiego R, Sun EW, Chen H, Czapla H, Wrasman K, Wu Y, Ko G, Ross T, Wendland B, De Camilli P. Epsin deficiency impairs endocytosis by stalling the actin-dependent invagination of endocytic clathrin-coated pits. eLife 2014; 3:e03311. [PMID: 25122462 PMCID: PMC4161027 DOI: 10.7554/elife.03311] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Epsin is an evolutionarily conserved endocytic clathrin adaptor whose most critical function(s) in clathrin coat dynamics remain(s) elusive. To elucidate such function(s), we generated embryonic fibroblasts from conditional epsin triple KO mice. Triple KO cells displayed a dramatic cell division defect. Additionally, a robust impairment in clathrin-mediated endocytosis was observed, with an accumulation of early and U-shaped pits. This defect correlated with a perturbation of the coupling between the clathrin coat and the actin cytoskeleton, which we confirmed in a cell-free assay of endocytosis. Our results indicate that a key evolutionary conserved function of epsin, in addition to other roles that include, as we show here, a low affinity interaction with SNAREs, is to help generate the force that leads to invagination and then fission of clathrin-coated pits.
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Affiliation(s)
- Mirko Messa
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Cell Biology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States
| | - Rubén Fernández-Busnadiego
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Cell Biology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States
| | - Elizabeth Wen Sun
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Cell Biology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States
| | - Hong Chen
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Cell Biology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States
| | - Heather Czapla
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Cell Biology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States
| | - Kristie Wrasman
- Department of Biology, Johns Hopkins University, Baltimore, United States
| | - Yumei Wu
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Cell Biology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States
| | - Genevieve Ko
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Cell Biology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States
| | - Theodora Ross
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, United States
| | - Beverly Wendland
- Department of Biology, Johns Hopkins University, Baltimore, United States
| | - Pietro De Camilli
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Cell Biology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States
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Lu L, Hong W. From endosomes to the trans-Golgi network. Semin Cell Dev Biol 2014; 31:30-9. [PMID: 24769370 DOI: 10.1016/j.semcdb.2014.04.024] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 04/16/2014] [Accepted: 04/16/2014] [Indexed: 12/11/2022]
Abstract
The retrograde trafficking from endosomes to the trans-Golgi network (TGN) is one of the major endocytic pathways to divert proteins and lipids away from lysosomal degradation. Retrograde transported cargos enter the TGN via two itineraries from either the early endosome/recycling endosome or the late endosome and involve various machinery components such as retromer, sorting nexins, clathrin, small GTPases, tethering factors and SNAREs. Recently, the pathway has been recognized for its role in signal transduction, physiology and pathogenesis of human diseases.
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Affiliation(s)
- Lei Lu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
| | - Wanjin Hong
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore; School of Pharmaceutical Sciences, Xiamen University, Xiamen, People's Republic of China
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PtdIns(4)P signalling and recognition systems. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 991:59-83. [PMID: 23775691 DOI: 10.1007/978-94-007-6331-9_5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The Golgi apparatus is a sorting platform that exchanges extensively with the endoplasmic reticulum (ER), endosomes (Es) and plasma membrane (PM) compartments. The last compartment of the Golgi, the trans-Golgi Network (TGN) is a large complex of highly deformed membranes from which vesicles depart to their targeted organelles but also are harbored from retrograde pathways. The phosphoinositide (PI) composition of the TGN is marked by an important contingent of phosphatidylinositol-4-phosphate (PtdIns(4)P). Although this PI is present throughout the Golgi, its proportion grows along the successive cisternae and peaks at the TGN. The levels of this phospholipid are controlled by a set of kinases and phosphatases that regulate its concentrations in the Golgi and maintain a dynamic gradient that determines the cellular localization of several interacting proteins. Though not exclusive to the Golgi, the synthesis of PtdIns(4)P in other membranes is relatively marginal and has unclear consequences. The significance of PtdIns(4)P within the TGN has been demonstrated for numerous cellular events such as vesicle formation, lipid metabolism, and membrane trafficking.
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Tan J, Brill JA. Cinderella story: PI4P goes from precursor to key signaling molecule. Crit Rev Biochem Mol Biol 2013; 49:33-58. [PMID: 24219382 DOI: 10.3109/10409238.2013.853024] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Phosphatidylinositol lipids are signaling molecules involved in nearly all aspects of cellular regulation. Production of phosphatidylinositol 4-phosphate (PI4P) has long been recognized as one of the first steps in generating poly-phosphatidylinositol phosphates involved in actin organization, cell migration, and signal transduction. In addition, progress over the last decade has brought to light independent roles for PI4P in membrane trafficking and lipid homeostasis. Here, we describe recent advances that reveal the breadth of processes regulated by PI4P, the spectrum of PI4P effectors, and the mechanisms of spatiotemporal control that coordinate crosstalk between PI4P and cellular signaling pathways.
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Affiliation(s)
- Julie Tan
- Department of Molecular Genetics, University of Toronto , Toronto, Ontario , Canada and
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36
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Holloway ZG, Velayos-Baeza A, Howell GJ, Levecque C, Ponnambalam S, Sztul E, Monaco AP. Trafficking of the Menkes copper transporter ATP7A is regulated by clathrin-, AP-2-, AP-1-, and Rab22-dependent steps. Mol Biol Cell 2013; 24:1735-48, S1-8. [PMID: 23596324 PMCID: PMC3667726 DOI: 10.1091/mbc.e12-08-0625] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
ATP7A mediates copper absorption and feeds cuproenzymes in the trans-Golgi network. To regulate copper homeostasis, ATP7A cycles between the TGN and plasma membrane. The roles of clathrin, adaptor complexes, lipid rafts, and Rab22a are assessed in an attempt to decipher the regulatory proteins involved in ATP7A cycling. The transporter ATP7A mediates systemic copper absorption and provides cuproenzymes in the trans-Golgi network (TGN) with copper. To regulate metal homeostasis, ATP7A constitutively cycles between the TGN and plasma membrane (PM). ATP7A trafficking to the PM is elevated in response to increased copper load and is reversed when copper concentrations are lowered. Molecular mechanisms underlying this trafficking are poorly understood. We assess the role of clathrin, adaptor complexes, lipid rafts, and Rab22a in an attempt to decipher the regulatory proteins involved in ATP7A cycling. While RNA interference (RNAi)–mediated depletion of caveolin 1/2 or flotillin had no effect on ATP7A localization, clathrin heavy chain depletion or expression of AP180 dominant-negative mutant not only disrupted clathrin-regulated pathways, but also blocked PM-to-TGN internalization of ATP7A. Depletion of the μ subunits of either adaptor protein-2 (AP-2) or AP-1 using RNAi further provides evidence that both clathrin adaptors are important for trafficking of ATP7A from the PM to the TGN. Expression of the GTP-locked Rab22aQ64L mutant caused fragmentation of TGN membrane domains enriched for ATP7A. These appear to be a subdomain of the mammalian TGN, showing only partial overlap with the TGN marker golgin-97. Of importance, ATP7A remained in the Rab22aQ64L-generated structures after copper treatment and washout, suggesting that forward trafficking out of this compartment was blocked. This study provides evidence that multiple membrane-associated factors, including clathrin, AP-2, AP-1, and Rab22, are regulators of ATP7A trafficking.
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Affiliation(s)
- Zoe G Holloway
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom
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37
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Pohler E, Mamai O, Hirst J, Zamiri M, Horn H, Nomura T, Irvine AD, Moran B, Wilson NJ, Smith FJD, Goh CSM, Sandilands A, Cole C, Barton GJ, Evans AT, Shimizu H, Akiyama M, Suehiro M, Konohana I, Shboul M, Teissier S, Boussofara L, Denguezli M, Saad A, Gribaa M, Dopping-Hepenstal PJ, McGrath JA, Brown SJ, Goudie DR, Reversade B, Munro CS, McLean WHI. Haploinsufficiency for AAGAB causes clinically heterogeneous forms of punctate palmoplantar keratoderma. Nat Genet 2012; 44:1272-6. [PMID: 23064416 PMCID: PMC3836166 DOI: 10.1038/ng.2444] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 09/21/2012] [Indexed: 01/28/2023]
Abstract
Palmoplantar keratodermas (PPKs) are a group of disorders that are diagnostically and therapeutically problematic in dermatogenetics. Punctate PPKs are characterized by circumscribed hyperkeratotic lesions on the palms and soles with considerable heterogeneity. In 18 families with autosomal dominant punctate PPK, we report heterozygous loss-of-function mutations in AAGAB, encoding α- and γ-adaptin-binding protein p34, located at a previously linked locus at 15q22. α- and γ-adaptin-binding protein p34, a cytosolic protein with a Rab-like GTPase domain, was shown to bind both clathrin adaptor protein complexes, indicating a role in membrane trafficking. Ultrastructurally, lesional epidermis showed abnormalities in intracellular vesicle biology. Immunohistochemistry showed hyperproliferation within the punctate lesions. Knockdown of AAGAB in keratinocytes led to increased cell division, which was linked to greatly elevated epidermal growth factor receptor (EGFR) protein expression and tyrosine phosphorylation. We hypothesize that p34 deficiency may impair endocytic recycling of growth factor receptors such as EGFR, leading to increased signaling and cellular proliferation.
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Affiliation(s)
- Elizabeth Pohler
- Centre for Dermatology and Genetic Medicine, College of Life Sciences and College of Medicine, Dentistry & Nursing, University of Dundee, UK
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Borner GHH, Antrobus R, Hirst J, Bhumbra GS, Kozik P, Jackson LP, Sahlender DA, Robinson MS. Multivariate proteomic profiling identifies novel accessory proteins of coated vesicles. ACTA ACUST UNITED AC 2012; 197:141-60. [PMID: 22472443 PMCID: PMC3317806 DOI: 10.1083/jcb.201111049] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A multivariate proteomics approach identified numerous new clathrin-coated vesicle proteins as well as the first AP-4 accessory protein, and also revealed how auxilin depletion causes mitotic arrest through sequestration of spindle proteins in clathrin cages. Despite recent advances in mass spectrometry, proteomic characterization of transport vesicles remains challenging. Here, we describe a multivariate proteomics approach to analyzing clathrin-coated vesicles (CCVs) from HeLa cells. siRNA knockdown of coat components and different fractionation protocols were used to obtain modified coated vesicle-enriched fractions, which were compared by stable isotope labeling of amino acids in cell culture (SILAC)-based quantitative mass spectrometry. 10 datasets were combined through principal component analysis into a “profiling” cluster analysis. Overall, 136 CCV-associated proteins were predicted, including 36 new proteins. The method identified >93% of established CCV coat proteins and assigned >91% correctly to intracellular or endocytic CCVs. Furthermore, the profiling analysis extends to less well characterized types of coated vesicles, and we identify and characterize the first AP-4 accessory protein, which we have named tepsin. Finally, our data explain how sequestration of TACC3 in cytosolic clathrin cages causes the severe mitotic defects observed in auxilin-depleted cells. The profiling approach can be adapted to address related cell and systems biological questions.
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Affiliation(s)
- Georg H H Borner
- Cambridge Institute for Medical Research, Wellcome Trust/Medical Research Council Building, University of Cambridge, Cambridge CB2 0XY, England, UK.
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Hirst J, D. Barlow L, Francisco GC, Sahlender DA, Seaman MNJ, Dacks JB, Robinson MS. The fifth adaptor protein complex. PLoS Biol 2011; 9:e1001170. [PMID: 22022230 PMCID: PMC3191125 DOI: 10.1371/journal.pbio.1001170] [Citation(s) in RCA: 220] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 08/30/2011] [Indexed: 11/18/2022] Open
Abstract
Adaptor protein (AP) complexes sort cargo into vesicles for transport from one membrane compartment of the cell to another. Four distinct AP complexes have been identified, which are present in most eukaryotes. We report the existence of a fifth AP complex, AP-5. Tagged AP-5 localises to a late endosomal compartment in HeLa cells. AP-5 does not associate with clathrin and is insensitive to brefeldin A. Knocking down AP-5 subunits interferes with the trafficking of the cation-independent mannose 6-phosphate receptor and causes the cell to form swollen endosomal structures with emanating tubules. AP-5 subunits can be found in all five eukaryotic supergroups, but they have been co-ordinately lost in many organisms. Concatenated phylogenetic analysis provides robust resolution, for the first time, into the evolutionary order of emergence of the adaptor subunit families, showing AP-3 as the basal complex, followed by AP-5, AP-4, and AP-1 and AP-2. Thus, AP-5 is an evolutionarily ancient complex, which is involved in endosomal sorting, and which has links with hereditary spastic paraplegia. Adaptor protein (AP) complexes facilitate the trafficking of cargo from one membrane compartment of the cell to another by recruiting other proteins to particular types of vesicles. For over 10 years, it has been assumed that there are four, and only four, distinct AP complexes in eukaryotic cells. We report the existence of a fifth AP complex, AP-5. Immunolocalisation and RNAi knockdown experiments both indicate that AP-5 is involved in trafficking proteins from endosomes towards other membranous compartments. There are genetic links between AP-5 and hereditary spastic paraplegia, a group of human genetic disorders characterised by progressive spasticity in the lower limbs. Phylogenetic analyses indicate that AP-5 was already present in the last eukaryotic common ancestor over a billion years ago.
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Affiliation(s)
- Jennifer Hirst
- University of Cambridge, Cambridge Institute for Medical Research, Cambridge, United Kingdom
| | - Lael D. Barlow
- Department of Cell Biology, University of Alberta, Edmonton, Canada
| | | | - Daniela A. Sahlender
- University of Cambridge, Cambridge Institute for Medical Research, Cambridge, United Kingdom
| | - Matthew N. J. Seaman
- University of Cambridge, Cambridge Institute for Medical Research, Cambridge, United Kingdom
| | - Joel B. Dacks
- Department of Cell Biology, University of Alberta, Edmonton, Canada
- * E-mail: (MSR); (JBD)
| | - Margaret S. Robinson
- University of Cambridge, Cambridge Institute for Medical Research, Cambridge, United Kingdom
- * E-mail: (MSR); (JBD)
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Epsin N-terminal homology domains bind on opposite sides of two SNAREs. Proc Natl Acad Sci U S A 2011; 108:12277-82. [PMID: 21746902 DOI: 10.1073/pnas.1013101108] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
SNARE proteins are crucial for membrane fusion in vesicular transport. To ensure efficient and accurate fusion, SNAREs need to be sorted into different budding vesicles. This process is usually regulated by specific recognition between SNAREs and their adaptor proteins. How different pairs of SNAREs and adaptors achieve their recognition is unclear. Here, we report the recognition between yeast SNARE Vti1p and its adaptor Ent3p derived from three crystal structures. Surprisingly, this yeast pair Vti1p/Ent3p interacts through a distinct binding site compared to their homologues vti1b/epsinR in mammals. An opposite surface on Vti1p_Habc domain binds to a conserved area on the epsin N-terminal homology (ENTH) domain of Ent3p. Two-hybrid, in vitro pull-down and in vivo experiments indicate this binding interface is important for correct localization of Vti1p in the cell. This previously undescribed discovery that a cargo and adaptor pair uses different binding sites across species suggests the diversity of SNARE-adaptor recognition in vesicular transport.
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Offenhäuser C, Lei N, Roy S, Collins BM, Stow JL, Murray RZ. Syntaxin 11 binds Vti1b and regulates late endosome to lysosome fusion in macrophages. Traffic 2011; 12:762-73. [PMID: 21388490 DOI: 10.1111/j.1600-0854.2011.01189.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Syntaxin 11 (Stx11) is a SNARE protein enriched in cells of the immune system. Loss or mutation of Stx11 results in familial hemophagocytic lymphohistiocytosis type-4 (FHL-4), an autosomal recessive disorder of immune dysregulation characterized by high levels of inflammatory cytokines along with defects in T-cell and natural killer cell function. We show here Stx11 is located on endosomal membranes including late endosomes and lysosomes in macrophages. While Stx11 did not form a typical trans-SNARE complex, it did bind to the Q-SNARE Vti1b and was able to regulate the availability of Vti1b to form the Q-SNARE complexes Stx6/Stx7/Vtib and Stx7/Stx8/Vti1b. The mutant form of Stx11 sequestered Vti1b from forming the Q-SNARE complex that mediates late endosome to lysosome fusion. Depletion of Stx11 in activated macrophages leads to an accumulation of enlarged late endocytic compartments, increased trafficking to the cell surface and inhibition of late endosome to lysosome fusion. These phenotypes are rescued by the expression of an siRNA-resistant Stx11 construct in Stx11-depleted cells. Our results suggest that by regulating the availability of Vti1b, Stx11 regulates trafficking steps between late endosomes, lysosomes and the cell surface in macrophages.
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Affiliation(s)
- Carolin Offenhäuser
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
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42
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Dissecting Ent3p: the ENTH domain binds different SNAREs via distinct amino acid residues while the C-terminus is sufficient for retrograde transport from endosomes. Biochem J 2010; 431:123-34. [PMID: 20658963 DOI: 10.1042/bj20100693] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The ENTH (epsin N-terminal homology) domain protein Ent3p and the ANTH [AP (adaptor protein)-180 N-terminal homology] domain protein Ent5p serve as partially redundant adaptors in vesicle budding from the TGN (trans-Golgi network) in Saccharomyces cerevisiae. They interact with phosphoinositides, clathrin, adaptor proteins and cargo such as chitin synthase Chs3p and SNAREs (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptors). In the present study, we show that ent3Δent5Δ cells displayed defects in cell separation and bud site selection. Ent3p and Ent5p were also involved in retrograde transport from early endosomes to the TGN because GFP (green fluorescent protein)-Snc1p shifted from a plasma membrane to an intracellular localization in ent3Δent5Δ cells. The C-terminal part of Ent3p was sufficient to restore retrograde transport from early endosomes to the TGN in ent3Δent5Δ cells. In contrast, the ENTH domain and the C-terminus were required for transport from the TGN to late endosomes, demonstrating that both functions are distinct. The ENTH domain of Ent3p is known to bind the N-terminal domains of the SNAREs Vti1p, Pep12p and Syn8p, which are required for fusion with late endosomes. The interaction surface between the Ent3p-related mammalian epsinR and vti1b is known. In the present paper, we show that Vti1p bound to the homologous surface patch of Ent3p. Pep12p and Syn8p interacted with the same surface area of Ent3p. However, different amino acid residues in Ent3p were crucial for the interaction with these SNAREs in two-hybrid assays. This provides the necessary flexibility to bind three SNAREs with little sequence homology but maintains the specificity of the interaction.
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43
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Fraldi A, Annunziata F, Lombardi A, Kaiser HJ, Medina DL, Spampanato C, Fedele AO, Polishchuk R, Sorrentino NC, Simons K, Ballabio A. Lysosomal fusion and SNARE function are impaired by cholesterol accumulation in lysosomal storage disorders. EMBO J 2010; 29:3607-20. [PMID: 20871593 PMCID: PMC2982760 DOI: 10.1038/emboj.2010.237] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 08/26/2010] [Indexed: 11/09/2022] Open
Abstract
The function of lysosomes relies on the ability of the lysosomal membrane to fuse with several target membranes in the cell. It is known that in lysosomal storage disorders (LSDs), lysosomal accumulation of several types of substrates is associated with lysosomal dysfunction and impairment of endocytic membrane traffic. By analysing cells from two severe neurodegenerative LSDs, we observed that cholesterol abnormally accumulates in the endolysosomal membrane of LSD cells, thereby reducing the ability of lysosomes to efficiently fuse with endocytic and autophagic vesicles. Furthermore, we discovered that soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptors (SNAREs), which are key components of the cellular membrane fusion machinery are aberrantly sequestered in cholesterol-enriched regions of LSD endolysosomal membranes. This abnormal spatial organization locks SNAREs in complexes and impairs their sorting and recycling. Importantly, reducing membrane cholesterol levels in LSD cells restores normal SNARE function and efficient lysosomal fusion. Our results support a model by which cholesterol abnormalities determine lysosomal dysfunction and endocytic traffic jam in LSDs by impairing the membrane fusion machinery, thus suggesting new therapeutic targets for the treatment of these disorders.
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Affiliation(s)
| | - Fabio Annunziata
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | - Alessia Lombardi
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | - Hermann-Josef Kaiser
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr., Dresden, Germany
| | | | | | | | - Roman Polishchuk
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
- Laboratory of Membrane Traffic, Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro (Chieti), Italy
| | | | - Kai Simons
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr., Dresden, Germany
| | - Andrea Ballabio
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
- Medical Genetics, Department of Pediatrics, Federico II University, Naples, Italy
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44
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Hoffmann A, Dannhauser PN, Groos S, Hinrichsen L, Curth U, Ungewickell EJ. A Comparison of GFP-Tagged Clathrin Light Chains with Fluorochromated Light Chains In Vivo and In Vitro. Traffic 2010; 11:1129-40. [DOI: 10.1111/j.1600-0854.2010.01084.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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45
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Robinson MS, Sahlender DA, Foster SD. Rapid inactivation of proteins by rapamycin-induced rerouting to mitochondria. Dev Cell 2010; 18:324-31. [PMID: 20159602 PMCID: PMC2845799 DOI: 10.1016/j.devcel.2009.12.015] [Citation(s) in RCA: 186] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Revised: 10/28/2009] [Accepted: 12/17/2009] [Indexed: 11/26/2022]
Abstract
We have developed a method for rapidly inactivating proteins with rapamycin-induced heterodimerization. Cells were stably transfected with siRNA-resistant, FKBP-tagged subunits of the adaptor protein (AP) complexes of clathrin-coated vesicles (CCVs), together with an FKBP and rapamycin-binding domain-containing construct with a mitochondrial targeting signal. Knocking down the endogenous subunit with siRNA, and then adding rapamycin, caused the APs to be rerouted to mitochondria within seconds. Rerouting AP-2 to mitochondria effectively abolished clathrin-mediated endocytosis of transferrin. In cells with rerouted AP-1, endocytosed cation-independent mannose 6-phosphate receptor (CIMPR) accumulated in a peripheral compartment, and isolated CCVs had reduced levels of CIMPR, but normal levels of the lysosomal hydrolase DNase II. Both observations support a role for AP-1 in retrograde trafficking. This type of approach, which we call a “knocksideways,” should be widely applicable as a means of inactivating proteins with a time scale of seconds or minutes rather than days.
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Affiliation(s)
- Margaret S Robinson
- University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, UK.
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46
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Hirst J, Sahlender DA, Choma M, Sinka R, Harbour ME, Parkinson M, Robinson MS. Spatial and Functional Relationship of GGAs and AP-1 inDrosophilaand HeLa Cells. Traffic 2009; 10:1696-710. [DOI: 10.1111/j.1600-0854.2009.00983.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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47
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Gordon DE, Mirza M, Sahlender DA, Jakovleska J, Peden AA. Coiled-coil interactions are required for post-Golgi R-SNARE trafficking. EMBO Rep 2009; 10:851-6. [PMID: 19557002 PMCID: PMC2726663 DOI: 10.1038/embor.2009.96] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Revised: 04/03/2009] [Accepted: 04/07/2009] [Indexed: 11/09/2022] Open
Abstract
The sorting of post-Golgi R-SNAREs (vesicle-associated membrane protein (VAMP)1, 2, 3, 4, 7 and 8) is still poorly understood. To address this, we developed a system to investigate their localization, trafficking and cell-surface levels. Here, we show that the distribution and internalization of VAMPs 3 and 8 are determined solely through a new conserved mechanism that uses coiled-coil interactions, and that VAMP4 does not require these interactions for its trafficking. We propose that VAMPs 3 and 8 are trafficked while in a complex with Q-SNAREs. We also show that the dileucine motif of VAMP4 is required for both its internalization and retrieval to the trans-Golgi network. However, when the dileucine motif is mutated, the construct can still be internalized potentially through coiled-coil interactions with Q-SNAREs.
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Affiliation(s)
- David E Gordon
- Department of Clinical Biochemistry, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB20XY, UK
| | - Myriam Mirza
- Department of Clinical Biochemistry, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB20XY, UK
| | - Daniela A Sahlender
- Department of Clinical Biochemistry, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB20XY, UK
| | - Jovana Jakovleska
- Department of Clinical Biochemistry, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB20XY, UK
| | - Andrew A Peden
- Department of Clinical Biochemistry, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB20XY, UK
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48
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Dodd ME, Hatzold J, Mathias JR, Walters KB, Bennin DA, Rhodes J, Kanki JP, Look AT, Hammerschmidt M, Huttenlocher A. The ENTH domain protein Clint1 is required for epidermal homeostasis in zebrafish. Development 2009; 136:2591-600. [PMID: 19570844 DOI: 10.1242/dev.038448] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Epidermal hyperproliferation and inflammation are hallmarks of the human condition psoriasis. Here, we report that a zebrafish line with a mutation in the cargo adaptor protein Clint1 exhibits psoriasis-like phenotypes including epithelial hyperproliferation and leukocyte infiltration. Clint1 is an ENTH domain-containing protein that binds SNARE proteins and functions in vesicle trafficking; however, its in vivo function in animal models has not been reported to date. The clint1 mutants exhibit chronic inflammation characterized by increased Interleukin 1beta expression, leukocyte infiltration, bidirectional trafficking and phagocytosis of cellular debris. The defects in clint1 mutants can be rescued by expression of zebrafish clint1 and can be phenocopied with clint1-specific morpholinos, supporting an essential role for Clint1 in epidermal development. Interaction studies suggest that Clint1 and Lethal giant larvae 2 function synergistically to regulate epidermal homeostasis. Accordingly, clint1 mutants show impaired hemidesmosome formation, loss of cell-cell contacts and increased motility suggestive of epithelial to mesenchymal transition. Taken together, our findings describe a novel function for the ENTH domain protein Clint1 in epidermal development and inflammation and suggest that its deficiency in zebrafish generates a phenotype that resembles the human condition psoriasis.
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Affiliation(s)
- M Ernest Dodd
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706, USA
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Lee JH, Overstreet E, Fitch E, Fleenor S, Fischer JA. Drosophila liquid facets-Related encodes Golgi epsin and is an essential gene required for cell proliferation, growth, and patterning. Dev Biol 2009; 331:1-13. [PMID: 19376106 DOI: 10.1016/j.ydbio.2009.03.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 03/11/2009] [Accepted: 03/12/2009] [Indexed: 12/12/2022]
Abstract
Epsin and epsin-Related (epsinR) are multi-modular proteins that stimulate clathrin-coated vesicle formation. Epsin promotes endocytosis at the plasma membrane, and epsinR functions at the Golgi and early endosomes for trans-Golgi network/endosome vesicle trafficking. In Drosophila, endocytic epsin is known as Liquid facets, and it is essential specifically for Notch signaling. Here, by generating and analyzing loss-of-function mutants in the liquid facets-Related (lqfR) gene of Drosophila, we investigated the function of Golgi epsin in a multicellular context. We found that LqfR is indeed a Golgi protein, and that like liquid facets, lqfR is essential for Drosophila viability. In addition, primarily by analyzing mutant eye discs, we found that lqfR is required for cell proliferation, insulin-independent cell growth, and cell patterning, consistent with a role in one or several signaling pathways. Epsins in all organisms share an ENTH (epsin N-terminal homology) domain, which binds phosphoinositides enriched at the plasma membrane or the Golgi membrane. The epsinR ENTH domain is also the recognition element for particular cargos. By generating wild-type and mutant lqfR transgenes, we found that all apparent LqfR functions are independent of its ENTH domain. These results suggest that LqfR transports specific cargo critical to one or more signaling pathways, and lays the foundation for identifying those proteins.
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Affiliation(s)
- Ji-Hoon Lee
- Section of Molecular Cell and Developmental Biology, Institute for Cell and Molecular Biology, The University of Texas at Austin, 1 University Station A4800, Austin, TX 78712, USA
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50
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Choudhury R, Noakes CJ, McKenzie E, Kox C, Lowe M. Differential clathrin binding and subcellular localization of OCRL1 splice isoforms. J Biol Chem 2009; 284:9965-73. [PMID: 19211563 DOI: 10.1074/jbc.m807442200] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutation of the inositol polyphosphate 5-phosphatase OCRL1 causes the X-linked disorder oculocerebrorenal syndrome of Lowe, characterized by defects in the brain, kidneys, and eyes. OCRL1 exists as two splice isoforms that differ by a single exon encoding 8 amino acids. The longer protein, termed isoform a, is the only form in brain, whereas both isoforms are present in all other tissues. The significance of OCRL1 splicing is currently unclear. Given its proximity to a clathrin-binding site, we hypothesized that splicing may alter the clathrin binding properties of OCRL1. Here we show that this is indeed the case. OCRL1 isoform a binds clathrin with higher affinity than isoform b and is significantly more enriched in clathrin-coated trafficking intermediates. We also identify a second clathrin-binding site in OCRL1 that contributes to clathrin binding of both isoforms. Association of OCRL1 with clathrin-coated intermediates requires membrane association through interaction with Rab GTPases but not binding to the clathrin adaptor AP2. Expression of OCRL1 isoform a lacking the 5-phosphatase domain impairs transferrin endocytosis, whereas an equivalent version of isoform b does not. Our results suggest that OCRL1 exists as two functional pools, one participating in clathrin-mediated trafficking events such as endocytosis and another that is much less or not involved in this process.
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Affiliation(s)
- Rawshan Choudhury
- Faculty of Life Sciences, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, United Kingdom
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