1
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Robinson MS, Antrobus R, Sanger A, Davies AK, Gershlick DC. The role of the AP-1 adaptor complex in outgoing and incoming membrane traffic. J Cell Biol 2024; 223:e202310071. [PMID: 38578286 PMCID: PMC10996651 DOI: 10.1083/jcb.202310071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 02/17/2024] [Accepted: 03/12/2024] [Indexed: 04/06/2024] Open
Abstract
The AP-1 adaptor complex is found in all eukaryotes, but it has been implicated in different pathways in different organisms. To look directly at AP-1 function, we generated stably transduced HeLa cells coexpressing tagged AP-1 and various tagged membrane proteins. Live cell imaging showed that AP-1 is recruited onto tubular carriers trafficking from the Golgi apparatus to the plasma membrane, as well as onto transferrin-containing early/recycling endosomes. Analysis of single AP-1 vesicles showed that they are a heterogeneous population, which starts to sequester cargo 30 min after exit from the ER. Vesicle capture showed that AP-1 vesicles contain transmembrane proteins found at the TGN and early/recycling endosomes, as well as lysosomal hydrolases, but very little of the anterograde adaptor GGA2. Together, our results support a model in which AP-1 retrieves proteins from post-Golgi compartments back to the TGN, analogous to COPI's role in the early secretory pathway. We propose that this is the function of AP-1 in all eukaryotes.
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Affiliation(s)
- Margaret S. Robinson
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Robin Antrobus
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Anneri Sanger
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Alexandra K. Davies
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - David C. Gershlick
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
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2
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Vassilopoulos S, Montagnac G. Clathrin assemblies at a glance. J Cell Sci 2024; 137:jcs261674. [PMID: 38668719 DOI: 10.1242/jcs.261674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2024] Open
Abstract
Clathrin assembles into honeycomb-like lattices at the plasma membrane but also on internal membranes, such as at the Golgi and tubular endosomes. Clathrin assemblies primarily regulate the intracellular trafficking of different cargoes, but clathrin also has non-endocytic functions in cell adhesion through interactions with specific integrins, contributes to intraluminal vesicle formation by forming flat bilayered coats on endosomes and even assembles on kinetochore k-fibers during mitosis. In this Cell Science at a Glance article and the accompanying poster, we review our current knowledge on the different types of canonical and non-canonical membrane-associated clathrin assemblies in mammalian cells, as observed by thin-section or platinum replica electron microscopy in various cell types, and discuss how the structural plasticity of clathrin contributes to its functional diversity.
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Affiliation(s)
- Stéphane Vassilopoulos
- Sorbonne Université, Inserm U974, Institut de Myologie, Centre de Recherche en Myologie, 75013 Paris, France
| | - Guillaume Montagnac
- Inserm U1279, Gustave Roussy Institute, Université Paris-Saclay, 94800 Villejuif, France
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3
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Hooy RM, Iwamoto Y, Tudorica DA, Ren X, Hurley JH. Self-assembly and structure of a clathrin-independent AP-1:Arf1 tubular membrane coat. SCIENCE ADVANCES 2022; 8:eadd3914. [PMID: 36269825 PMCID: PMC9586487 DOI: 10.1126/sciadv.add3914] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 09/01/2022] [Indexed: 05/28/2023]
Abstract
The adaptor protein (AP) complexes not only form the inner layer of clathrin coats but also have clathrin-independent roles in membrane traffic whose mechanisms are unknown. HIV-1 Nef hijacks AP-1 to sequester major histocompatibility complex class I (MHC-I), evading immune detection. We found that AP-1:Arf1:Nef:MHC-I forms a coat on tubulated membranes without clathrin and determined its structure. The coat assembles via Arf1 dimer interfaces. AP-1-positive tubules are enriched in cells upon clathrin knockdown. Nef localizes preferentially to AP-1 tubules in cells, explaining how Nef sequesters MHC-I. Coat contact residues are conserved across Arf isoforms and the Arf-dependent AP complexes AP-1, AP-3, and AP-4. Thus, AP complexes can self-assemble with Arf1 into tubular coats without clathrin or other scaffolding factors. The AP-1:Arf1 coat defines the structural basis of a broader class of tubulovesicular membrane coats as an intermediate in clathrin vesicle formation from internal membranes and as an MHC-I sequestration mechanism in HIV-1 infection.
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Affiliation(s)
- Richard M. Hooy
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Yuichiro Iwamoto
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Dan A. Tudorica
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
- Graduate Group in Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Xuefeng Ren
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - James H. Hurley
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
- Graduate Group in Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
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4
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Quidwai T, Wang J, Hall EA, Petriman NA, Leng W, Kiesel P, Wells JN, Murphy LC, Keighren MA, Marsh JA, Lorentzen E, Pigino G, Mill P. A WDR35-dependent coat protein complex transports ciliary membrane cargo vesicles to cilia. eLife 2021; 10:e69786. [PMID: 34734804 PMCID: PMC8754431 DOI: 10.7554/elife.69786] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 11/04/2021] [Indexed: 11/13/2022] Open
Abstract
Intraflagellar transport (IFT) is a highly conserved mechanism for motor-driven transport of cargo within cilia, but how this cargo is selectively transported to cilia is unclear. WDR35/IFT121 is a component of the IFT-A complex best known for its role in ciliary retrograde transport. In the absence of WDR35, small mutant cilia form but fail to enrich in diverse classes of ciliary membrane proteins. In Wdr35 mouse mutants, the non-core IFT-A components are degraded and core components accumulate at the ciliary base. We reveal deep sequence homology of WDR35 and other IFT-A subunits to α and ß' COPI coatomer subunits and demonstrate an accumulation of 'coat-less' vesicles that fail to fuse with Wdr35 mutant cilia. We determine that recombinant non-core IFT-As can bind directly to lipids and provide the first in situ evidence of a novel coat function for WDR35, likely with other IFT-A proteins, in delivering ciliary membrane cargo necessary for cilia elongation.
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Affiliation(s)
- Tooba Quidwai
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
| | - Jiaolong Wang
- Department of Molecular Biology and Genetics, Aarhus UniversityAarhusDenmark
| | - Emma A Hall
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
| | - Narcis A Petriman
- Department of Molecular Biology and Genetics, Aarhus UniversityAarhusDenmark
| | - Weihua Leng
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
| | - Petra Kiesel
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
| | - Jonathan N Wells
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
| | - Laura C Murphy
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
| | - Margaret A Keighren
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
| | - Joseph A Marsh
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
| | - Esben Lorentzen
- Department of Molecular Biology and Genetics, Aarhus UniversityAarhusDenmark
| | - Gaia Pigino
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- Human TechnopoleMilanItaly
| | - Pleasantine Mill
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
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5
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Usmani MA, Ahmed ZM, Magini P, Pienkowski VM, Rasmussen KJ, Hernan R, Rasheed F, Hussain M, Shahzad M, Lanpher BC, Niu Z, Lim FY, Pippucci T, Ploski R, Kraus V, Matuszewska K, Palombo F, Kianmahd J, Martinez-Agosto JA, Lee H, Colao E, Motazacker MM, Brigatti KW, Puffenberger EG, Riazuddin SA, Gonzaga-Jauregui C, Chung WK, Wagner M, Schultz MJ, Seri M, Kievit AJ, Perrotti N, Klein Wassink-Ruiter J, van Bokhoven H, Riazuddin S, Riazuddin S, Riazuddin S. De novo and bi-allelic variants in AP1G1 cause neurodevelopmental disorder with developmental delay, intellectual disability, and epilepsy. Am J Hum Genet 2021; 108:1330-1341. [PMID: 34102099 DOI: 10.1016/j.ajhg.2021.05.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 05/14/2021] [Indexed: 12/15/2022] Open
Abstract
Adaptor protein (AP) complexes mediate selective intracellular vesicular trafficking and polarized localization of somatodendritic proteins in neurons. Disease-causing alleles of various subunits of AP complexes have been implicated in several heritable human disorders, including intellectual disabilities (IDs). Here, we report two bi-allelic (c.737C>A [p.Pro246His] and c.1105A>G [p.Met369Val]) and eight de novo heterozygous variants (c.44G>A [p.Arg15Gln], c.103C>T [p.Arg35Trp], c.104G>A [p.Arg35Gln], c.229delC [p.Gln77Lys∗11], c.399_400del [p.Glu133Aspfs∗37], c.747G>T [p.Gln249His], c.928-2A>C [p.?], and c.2459C>G [p.Pro820Arg]) in AP1G1, encoding gamma-1 subunit of adaptor-related protein complex 1 (AP1γ1), associated with a neurodevelopmental disorder (NDD) characterized by mild to severe ID, epilepsy, and developmental delay in eleven families from different ethnicities. The AP1γ1-mediated adaptor complex is essential for the formation of clathrin-coated intracellular vesicles. In silico analysis and 3D protein modeling simulation predicted alteration of AP1γ1 protein folding for missense variants, which was consistent with the observed altered AP1γ1 levels in heterologous cells. Functional studies of the recessively inherited missense variants revealed no apparent impact on the interaction of AP1γ1 with other subunits of the AP-1 complex but rather showed to affect the endosome recycling pathway. Knocking out ap1g1 in zebrafish leads to severe morphological defect and lethality, which was significantly rescued by injection of wild-type AP1G1 mRNA and not by transcripts encoding the missense variants. Furthermore, microinjection of mRNAs with de novo missense variants in wild-type zebrafish resulted in severe developmental abnormalities and increased lethality. We conclude that de novo and bi-allelic variants in AP1G1 are associated with neurodevelopmental disorder in diverse populations.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Saima Riazuddin
- Department of Otorhinolaryngology Head and Neck Surgery, School of Medicine, University of Maryland, Baltimore, MD 21201, USA; Department of Molecular Biology and Biochemistry, School of Medicine, University of Maryland, Baltimore, MD 21201, USA.
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6
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Kim SH, Cho JH, Park BO, Park BC, Kim JH, Park SG, Kim S. Phosphorylation of REPS1 at Ser709 by RSK attenuates the recycling of transferrin receptor. BMB Rep 2021. [PMID: 33407999 PMCID: PMC8167248 DOI: 10.5483/bmbrep.2021.54.5.266] [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] [Indexed: 11/20/2022] Open
Abstract
RalBP1 associated EPS domain containing 1 (REPS1) is conserved from Drosophila to humans and implicated in the endocytic system. However, an exact role of REPS1 remains largely unknown. Here, we demonstrated that mitogen activated protein kinase kinase (MEK)-p90 ribosomal S6 Kinase (RSK) signaling pathway directly phosphorylated REPS1 at Ser709 upon stimulation by epidermal growth factor (EGF) and amino acid. While REPS2 is known to be involved in the endocytosis of EGF receptor (EGFR), REPS1 knockout (KO) cells did not show any defect in the endocytosis of EGFR. However, in the REPS1 KO cells and the KO cells reconstituted with a non-phosphorylatable REPS1 (REPS1 S709A), the recycling of transferrin receptor (TfR) was attenuated compared to the cells reconstituted with wild type REPS1. Collectively, we suggested that the phosphorylation of REPS1 at S709 by RSK may have a role of the trafficking of TfR.
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Affiliation(s)
- Seong Heon Kim
- Department of Functional Genomics, KRIBB School of Biological Science, Korea University of Science and Technology, Daejeon 34113, Korea
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
| | - Jin-hwa Cho
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
| | - Bi-Oh Park
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
- College of Pharmacy, Chungbuk National University, Cheongju 28160, Korea
| | - Byoung Chul Park
- Department of Functional Genomics, KRIBB School of Biological Science, Korea University of Science and Technology, Daejeon 34113, Korea
- Department of Proteome Structural Biology, KRIBB School of Biological Science, Korea University of Science and Technology, Daejeon 34113, Korea
| | - Jeong-Hoon Kim
- Department of Functional Genomics, KRIBB School of Biological Science, Korea University of Science and Technology, Daejeon 34113, Korea
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
| | - Sung Goo Park
- Department of Functional Genomics, KRIBB School of Biological Science, Korea University of Science and Technology, Daejeon 34113, Korea
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
| | - Sunhong Kim
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
- Department of Biomolecular Science, KRIBB School of Biological Science, Korea University of Science and Technology, Daejeon 34113, Korea
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7
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Fujii S, Kurokawa K, Tago T, Inaba R, Takiguchi A, Nakano A, Satoh T, Satoh AK. Sec71 separates Golgi stacks in Drosophila S2 cells. J Cell Sci 2020; 133:jcs245571. [PMID: 33262309 PMCID: PMC10668125 DOI: 10.1242/jcs.245571] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 11/18/2020] [Indexed: 01/19/2023] Open
Abstract
Golgi stacks are the basic structural units of the Golgi. Golgi stacks are separated from each other and scattered in the cytoplasm of Drosophila cells. Here, we report that the ARF-GEF inhibitor Brefeldin A (BFA) induces the formation of BFA bodies, which are aggregates of Golgi stacks, trans-Golgi networks and recycling endosomes. Recycling endosomes are located in the centers of BFA bodies, while Golgi stacks surround them on their trans sides. Live imaging of S2 cells revealed that Golgi stacks repeatedly merged and separated on their trans sides, and BFA caused successive merger by inhibiting separation, forming BFA bodies. S2 cells carrying genome-edited BFA-resistant mutant Sec71M717L did not form BFA bodies at high concentrations of BFA; S2 cells carrying genome-edited BFA-hypersensitive mutant Sec71F713Y produced BFA bodies at low concentrations of BFA. These results indicate that Sec71 is the sole BFA target for BFA body formation and controls Golgi stack separation. Finally, we showed that impairment of Sec71 in fly photoreceptors induces BFA body formation, with accumulation of both apical and basolateral cargoes, resulting in inhibition of polarized transport.
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Affiliation(s)
- Syara Fujii
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Kazuo Kurokawa
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Tatsuya Tago
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Ryota Inaba
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Arata Takiguchi
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Akihiko Nakano
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Takunori Satoh
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Akiko K Satoh
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
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8
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The Host GTPase Arf1 and Its Effectors AP1 and PICK1 Stimulate Actin Polymerization and Exocytosis To Promote Entry of Listeria monocytogenes. Infect Immun 2020; 88:IAI.00578-19. [PMID: 31740529 DOI: 10.1128/iai.00578-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 11/10/2019] [Indexed: 12/20/2022] Open
Abstract
Listeria monocytogenes is a foodborne bacterium that causes gastroenteritis, meningitis, or abortion. Listeria induces its internalization (entry) into some human cells through interaction of the bacterial surface protein InlB with its host receptor, the Met tyrosine kinase. InlB and Met promote entry through stimulation of localized actin polymerization and exocytosis. How actin cytoskeletal changes and exocytosis are controlled during entry is not well understood. Here, we demonstrate important roles for the host GTPase Arf1 and its effectors AP1 and PICK1 in actin polymerization and exocytosis during InlB-dependent uptake. Depletion of Arf1 by RNA interference (RNAi) or inhibition of Arf1 activity using a dominant-negative allele impaired InlB-dependent internalization, indicating an important role for Arf1 in this process. InlB stimulated an increase in the GTP-bound form of Arf1, demonstrating that this bacterial protein activates Arf1. RNAi and immunolocalization studies indicated that Arf1 controls exocytosis and actin polymerization during entry by recruiting the effectors AP1 and PICK1 to the plasma membrane. In turn, AP1 and PICK1 promoted plasma membrane translocation of both Filamin A (FlnA) and Exo70, two host proteins previously found to mediate exocytosis during InlB-dependent internalization (M. Bhalla, H. Van Ngo, G. C. Gyanwali, and K. Ireton, Infect Immun 87:e00689-18, 2018, https://doi.org/10.1128/IAI.00689-18). PICK1 mediated recruitment of Exo70 but not FlnA. Collectively, these results indicate that Arf1, AP1, and PICK1 stimulate exocytosis by redistributing FlnA and Exo70 to the plasma membrane. We propose that Arf1, AP1, and PICK1 are key coordinators of actin polymerization and exocytosis during infection of host cells by Listeria.
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9
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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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Affiliation(s)
- Eleanor A Latomanski
- Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Hayley J Newton
- Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
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10
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Fermie J, Liv N, Ten Brink C, van Donselaar EG, Müller WH, Schieber NL, Schwab Y, Gerritsen HC, Klumperman J. Single organelle dynamics linked to 3D structure by correlative live-cell imaging and 3D electron microscopy. Traffic 2018; 19:354-369. [PMID: 29451726 DOI: 10.1111/tra.12557] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 02/13/2018] [Accepted: 02/13/2018] [Indexed: 01/05/2023]
Abstract
Live-cell correlative light-electron microscopy (live-cell-CLEM) integrates live movies with the corresponding electron microscopy (EM) image, but a major challenge is to relate the dynamic characteristics of single organelles to their 3-dimensional (3D) ultrastructure. Here, we introduce focused ion beam scanning electron microscopy (FIB-SEM) in a modular live-cell-CLEM pipeline for a single organelle CLEM. We transfected cells with lysosomal-associated membrane protein 1-green fluorescent protein (LAMP-1-GFP), analyzed the dynamics of individual GFP-positive spots, and correlated these to their corresponding fine-architecture and immediate cellular environment. By FIB-SEM we quantitatively assessed morphological characteristics, like number of intraluminal vesicles and contact sites with endoplasmic reticulum and mitochondria. Hence, we present a novel way to integrate multiple parameters of subcellular dynamics and architecture onto a single organelle, which is relevant to address biological questions related to membrane trafficking, organelle biogenesis and positioning. Furthermore, by using CLEM to select regions of interest, our method allows for targeted FIB-SEM, which significantly reduces time required for image acquisition and data processing.
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Affiliation(s)
- Job Fermie
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
- Section Molecular Biophysics, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands
| | - Nalan Liv
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Corlinda Ten Brink
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Elly G van Donselaar
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Wally H Müller
- Section Cryo-EM, Department of Chemistry, Utrecht University, Utrecht, The Netherlands
| | - Nicole L Schieber
- Electron Microscopy Core Facility, EMBL Heidelberg, Heidelberg, Germany
| | - Yannick Schwab
- Electron Microscopy Core Facility, EMBL Heidelberg, Heidelberg, Germany
| | - Hans C Gerritsen
- Section Molecular Biophysics, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands
| | - Judith Klumperman
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
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11
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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: 28] [Impact Index Per Article: 3.1] [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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12
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Tomas A, Vaughan SO, Burgoyne T, Sorkin A, Hartley JA, Hochhauser D, Futter CE. WASH and Tsg101/ALIX-dependent diversion of stress-internalized EGFR from the canonical endocytic pathway. Nat Commun 2015; 6:7324. [PMID: 26066081 PMCID: PMC4490399 DOI: 10.1038/ncomms8324] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 04/27/2015] [Indexed: 12/14/2022] Open
Abstract
Stress exposure triggers ligand-independent EGF receptor (EGFR) endocytosis, but its post-endocytic fate and role in regulating signalling are unclear. We show that the p38 MAP kinase-dependent, EGFR tyrosine kinase (TK)-independent EGFR internalization induced by ultraviolet light C (UVC) or the cancer therapeutic cisplatin, is followed by diversion from the canonical endocytic pathway. Instead of lysosomal degradation or plasma membrane recycling, EGFR accumulates in a subset of LBPA-rich perinuclear multivesicular bodies (MVBs) distinct from those carrying EGF-stimulated EGFR. Stress-internalized EGFR co-segregates with exogenously expressed pre-melanosomal markers OA1 and fibrillar PMEL, following early endosomal sorting by the actin polymerization-promoting WASH complex. Stress-internalized EGFR is retained intracellularly by continued p38 activity in a mechanism involving ubiquitin-independent, ESCRT/ALIX-dependent incorporation onto intraluminal vesicles (ILVs) of MVBs. In contrast to the internalization-independent EGF-stimulated activation, UVC/cisplatin-triggered EGFR activation depends on EGFR internalization and intracellular retention. EGFR signalling from this MVB subpopulation delays apoptosis and might contribute to chemoresistance.
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Affiliation(s)
- Alejandra Tomas
- Department of Cell Biology, UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
- Present address: Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK
| | - Simon O. Vaughan
- Department of Cell Biology, UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Thomas Burgoyne
- Department of Cell Biology, UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Alexander Sorkin
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
| | - John A. Hartley
- Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street, London WC1E 6BT, UK
| | - Daniel Hochhauser
- Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street, London WC1E 6BT, UK
| | - Clare E. Futter
- Department of Cell Biology, UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
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13
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14
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Wavre-Shapton ST, Meschede IP, Seabra MC, Futter CE. Phagosome maturation during endosome interaction revealed by partial rhodopsin processing in retinal pigment epithelium. J Cell Sci 2014; 127:3852-61. [PMID: 25074813 PMCID: PMC4150067 DOI: 10.1242/jcs.154757] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Defects in phagocytosis and degradation of photoreceptor outer segments (POS) by the retinal pigment epithelium (RPE) are associated with aging and retinal disease. The daily burst of rod outer segment (ROS) phagocytosis by the RPE provides a unique opportunity to analyse phagosome processing in vivo. In mouse retinae, phagosomes containing stacked rhodopsin-rich discs were identified by immuno-electron microscopy. Early apical phagosomes stained with antibodies against both cytoplasmic and intradiscal domains of rhodopsin. During phagosome maturation, a remarkably synchronised loss of the cytoplasmic epitope coincided with movement to the cell body and preceded phagosome-lysosome fusion and disc degradation. Loss of the intradiscal rhodopsin epitope and disc digestion occurred upon fusion with cathepsin-D-positive lysosomes. The same sequential stages of phagosome maturation were identified in cultured RPE and macrophages challenged with isolated POS. Loss of the cytoplasmic rhodopsin epitope was insensitive to pH but sensitive to protease inhibition and coincided with the interaction of phagosomes with endosomes. Thus, during pre-lysosomal maturation of ROS-containing phagosomes, limited rhodopsin processing occurs upon interaction with endosomes. This potentially provides a sensitive readout of phagosome-endosome interactions that is applicable to multiple phagocytes.
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Affiliation(s)
- Silène T Wavre-Shapton
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Ingrid P Meschede
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Miguel C Seabra
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK CEDOC, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1169-056 Lisbon, Portugal Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
| | - Clare E Futter
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
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15
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Abstract
Live-cell imaging reveals the endolysosomal system as a complex and highly dynamic network of interacting compartments. Distinct types of endosomes are discerned by kinetic, molecular, and morphological criteria. Although none of these criteria, or combinations thereof, can capture the full complexity of the endolysosomal system, they are extremely useful for experimental purposes. Some membrane domain specializations and specific morphological characteristics can only be seen by ultrastructural analysis after preparation for electron microscopy (EM). Immuno-EM allows a further discrimination of seemingly identical compartments by their molecular makeup. In this review we provide an overview of the ultrastructural characteristics and membrane organization of endosomal compartments, along with their organizing machineries.
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Affiliation(s)
- Judith Klumperman
- Department of Cell Biology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Graça Raposo
- Institut Curie, Centre de Recherche, Paris F-75248, France Structure and Membrane Compartments CNRS UMR144, Paris F-75248, France
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16
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Abstract
Polarized cells such as epithelial cells and neurons exhibit different plasma membrane domains with distinct protein compositions. Recent studies have shown that sorting of transmembrane proteins to the basolateral domain of epithelial cells and the somatodendritic domain of neurons is mediated by recognition of signals in the cytosolic domains of the proteins by adaptors. These adaptors are components of protein coats associated with the trans-Golgi network and/or recycling endosomes. The clathrin-associated adaptor protein 1 (AP-1) complex plays a preeminent role in this process, although other adaptors and coat proteins, such as AP-4, ARH, Numb, exomer, and retromer, have also been implicated.
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Affiliation(s)
- Juan S Bonifacino
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
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17
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Bertuccio CA, Lee SL, Wu G, Butterworth MB, Hamilton KL, Devor DC. Anterograde trafficking of KCa3.1 in polarized epithelia is Rab1- and Rab8-dependent and recycling endosome-independent. PLoS One 2014; 9:e92013. [PMID: 24632741 PMCID: PMC3954861 DOI: 10.1371/journal.pone.0092013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 02/16/2014] [Indexed: 02/01/2023] Open
Abstract
The intermediate conductance, Ca2+-activated K+ channel (KCa3.1) targets to the basolateral (BL) membrane in polarized epithelia where it plays a key role in transepithelial ion transport. However, there are no studies defining the anterograde and retrograde trafficking of KCa3.1 in polarized epithelia. Herein, we utilize Biotin Ligase Acceptor Peptide (BLAP)-tagged KCa3.1 to address these trafficking steps in polarized epithelia, using MDCK, Caco-2 and FRT cells. We demonstrate that KCa3.1 is exclusively targeted to the BL membrane in these cells when grown on filter supports. Following endocytosis, KCa3.1 degradation is prevented by inhibition of lysosomal/proteosomal pathways. Further, the ubiquitylation of KCa3.1 is increased following endocytosis from the BL membrane and PR-619, a deubiquitylase inhibitor, prevents degradation, indicating KCa3.1 is targeted for degradation by ubiquitylation. We demonstrate that KCa3.1 is targeted to the BL membrane in polarized LLC-PK1 cells which lack the μ1B subunit of the AP-1 complex, indicating BL targeting of KCa3.1 is independent of μ1B. As Rabs 1, 2, 6 and 8 play roles in ER/Golgi exit and trafficking of proteins to the BL membrane, we evaluated the role of these Rabs in the trafficking of KCa3.1. In the presence of dominant negative Rab1 or Rab8, KCa3.1 cell surface expression was significantly reduced, whereas Rabs 2 and 6 had no effect. We also co-immunoprecipitated KCa3.1 with both Rab1 and Rab8. These results suggest these Rabs are necessary for the anterograde trafficking of KCa3.1. Finally, we determined whether KCa3.1 traffics directly to the BL membrane or through recycling endosomes in MDCK cells. For these studies, we used either recycling endosome ablation or dominant negative RME-1 constructs and determined that KCa3.1 is trafficked directly to the BL membrane rather than via recycling endosomes. These results are the first to describe the anterograde and retrograde trafficking of KCa3.1 in polarized epithelia cells.
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Affiliation(s)
- Claudia A. Bertuccio
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Shih-Liang Lee
- Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, Otago, New Zealand
| | - Guangyu Wu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
| | - Michael B. Butterworth
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Kirk L. Hamilton
- Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, Otago, New Zealand
- * E-mail: (DCD); (KLH)
| | - Daniel C. Devor
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail: (DCD); (KLH)
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18
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Guo X, Mattera R, Ren X, Chen Y, Retamal C, González A, Bonifacino JS. The adaptor protein-1 μ1B subunit expands the repertoire of basolateral sorting signal recognition in epithelial cells. Dev Cell 2014; 27:353-66. [PMID: 24229647 DOI: 10.1016/j.devcel.2013.10.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Revised: 07/15/2013] [Accepted: 10/10/2013] [Indexed: 01/05/2023]
Abstract
An outstanding question in protein sorting is why polarized epithelial cells express two isoforms of the μ1 subunit of the AP-1 clathrin adaptor complex: the ubiquitous μ1A and the epithelial-specific μ1B. Previous studies led to the notion that μ1A and μ1B mediate basolateral sorting predominantly from the trans-Golgi network (TGN) and recycling endosomes, respectively. Using improved analytical tools, however, we find that μ1A and μ1B largely colocalize with each other. They also colocalize to similar extents with TGN and recycling endosome markers, as well as with basolateral cargoes transiting biosynthetic and endocytic-recycling routes. Instead, the two isoforms differ in their signal-recognition specificity. In particular, μ1B preferentially binds a subset of signals from cargoes that are sorted basolaterally in a μ1B-dependent manner. We conclude that expression of distinct μ1 isoforms in epithelial cells expands the repertoire of signals recognized by AP-1 for sorting of a broader range of cargoes to the basolateral surface.
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Affiliation(s)
- Xiaoli Guo
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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19
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Abstract
Hepatocytes, like other epithelia, are situated at the interface between the organism's exterior and the underlying internal milieu and organize the vectorial exchange of macromolecules between these two spaces. To mediate this function, epithelial cells, including hepatocytes, are polarized with distinct luminal domains that are separated by tight junctions from lateral domains engaged in cell-cell adhesion and from basal domains that interact with the underlying extracellular matrix. Despite these universal principles, hepatocytes distinguish themselves from other nonstriated epithelia by their multipolar organization. Each hepatocyte participates in multiple, narrow lumina, the bile canaliculi, and has multiple basal surfaces that face the endothelial lining. Hepatocytes also differ in the mechanism of luminal protein trafficking from other epithelia studied. They lack polarized protein secretion to the luminal domain and target single-spanning and glycosylphosphatidylinositol-anchored bile canalicular membrane proteins via transcytosis from the basolateral domain. We compare this unique hepatic polarity phenotype with that of the more common columnar epithelial organization and review our current knowledge of the signaling mechanisms and the organization of polarized protein trafficking that govern the establishment and maintenance of hepatic polarity. The serine/threonine kinase LKB1, which is activated by the bile acid taurocholate and, in turn, activates adenosine monophosphate kinase-related kinases including AMPK1/2 and Par1 paralogues has emerged as a key determinant of hepatic polarity. We propose that the absence of a hepatocyte basal lamina and differences in cell-cell adhesion signaling that determine the positioning of tight junctions are two crucial determinants for the distinct hepatic and columnar polarity phenotypes.
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Affiliation(s)
- Aleksandr Treyer
- Albert Einstein College of Medicine, Department of Developmental and Molecular Biology, Bronx, New York, USA
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20
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Perrin L, Laura P, Lacas-Gervais S, Sandra LG, Gilleron J, Jérôme G, Ceppo F, Franck C, Prodon F, François P, Benmerah A, Alexandre B, Tanti JF, Jean-François T, Cormont M, Mireille C. Rab4b controls an early endosome sorting event by interacting with the γ-subunit of the clathrin adaptor complex 1. J Cell Sci 2013; 126:4950-62. [PMID: 24006255 DOI: 10.1242/jcs.130575] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The endocytic pathway is essential for cell homeostasis and numerous small Rab GTPases are involved in its control. The endocytic trafficking step controlled by Rab4b has not been elucidated, although recent data suggested it could be important for glucose homeostasis, synaptic homeostasis or adaptive immunity. Here, we show that Rab4b is required for early endosome sorting of transferrin receptors (TfRs) to the recycling endosomes, and we identified the AP1γ subunit of the clathrin adaptor AP-1 as a Rab4b effector and key component of the machinery of early endosome sorting. We show that internalised transferrin (Tf) does not reach Vamp3/Rab11 recycling endosomes in the absence of Rab4b, whereas it is rapidly recycled back to the plasma membrane. By contrast, overexpression of Rab4b leads to the accumulation of internalised Tf within AP-1- and clathrin-coated vesicles. These vesicles are poor in early and recycling endocytic markers except for TfR and require AP1γ for their formation. Furthermore, the targeted overexpression of the Rab4b-binding domain of AP1γ to early endosome upon its fusion with FYVE domains inhibited the interaction between Rab4b and endogenous AP1γ, and perturbed Tf traffic. We thus proposed that the interaction between early endocytic Rab4b and AP1γ could allow the budding of clathrin-coated vesicles for subsequent traffic to recycling endosomes. The data also uncover a novel type of endosomes, characterised by low abundance of either early or recycling endocytic markers, which could potentially be generated in cell types that naturally express high level of Rab4b.
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Affiliation(s)
| | - Perrin Laura
- INSERM U1065, Centre Méditerranéen de Médecine Moléculaire C3M, Nice, France
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21
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Humphries AC, Way M. The non-canonical roles of clathrin and actin in pathogen internalization, egress and spread. Nat Rev Microbiol 2013; 11:551-60. [PMID: 24020073 DOI: 10.1038/nrmicro3072] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The role of clathrin in pathogen entry has received much attention and has highlighted the adaptability of clathrin during internalization. Recent studies have now uncovered additional roles for clathrin and have put the spotlight on its role in pathogen spread. Here, we discuss the manipulation of clathrin by pathogens, with specific attention to the processes that occur at the plasma membrane. In the majority of cases, both clathrin and the actin cytoskeleton are hijacked, so we also examine the interplay between these two systems and their role during pathogen internalization, egress and spread.
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Affiliation(s)
- Ashley C Humphries
- Cancer Research UK London Research Institute, 44 Lincoln’s Inn Fields, London WC2A 3LY, UK
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22
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Vesicles modulate an actin network for asymmetric spindle positioning. Nat Cell Biol 2013; 15:937-47. [PMID: 23873150 PMCID: PMC3797517 DOI: 10.1038/ncb2802] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 06/06/2013] [Indexed: 12/12/2022]
Abstract
Actin networks drive many essential cellular processes, including cell migration, cytokinesis and tissue morphogenesis. However, how cells organize and regulate dynamic actin networks that consist of long, unbranched actin filaments is only poorly understood. This study in mouse oocytes reveals that cells can use vesicles as adaptable, motorized network nodes to regulate the dynamics and density of intracellular actin networks. In particular, Rab11a-positive vesicles drive the network dynamics in a myosin-Vb-dependent manner, and modulate the network density by sequestering and clustering the network's actin nucleators. We also report a simple way by which networks of different densities can be generated, namely by adjusting the number and volume of vesicles in the cell. This vesicle-based mechanism of actin network modulation is essential for asymmetric positioning of the meiotic spindle in mouse oocytes, a vital step in the development of a fertilizable egg in mammals.
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23
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Streptococcus pneumoniae invades endothelial host cells via multiple pathways and is killed in a lysosome dependent manner. PLoS One 2013; 8:e65626. [PMID: 23785439 PMCID: PMC3681976 DOI: 10.1371/journal.pone.0065626] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 04/25/2013] [Indexed: 11/19/2022] Open
Abstract
Streptococcus pneumoniae is one of the major causative agents of pneumonia, sepsis, meningitis and other morbidities. In spite of its heavy disease burden, surprisingly little is known about the mechanisms involved in the switch of life style, from commensal colonizer of the nasopharynx to invasive pathogen. In vitro experiments, and mouse models have shown that S. pneumoniae can be internalized by host cells, which coupled with intracellular vesicle transport through the cells, i.e. transcytosis, is suggested to be the first step of invasive disease. To further dissect the process of S. pneumoniae internalization, we chemically inhibited discrete parts of the cellular uptake system. We show that this invasion of the host cells was facilitated via both clathrin- and caveolae-mediated endocytosis. After internalization we demonstrated that the bulk of the internalized S. pneumoniae was killed in the lysosome. Interestingly, inhibition of the lysosome altered transcytosis dynamics as it resulted in an increase in the transport of the internalized bacteria out of the cells via the basal side. These results show that uptake of S. pneumoniae into host cells occurs via multiple pathways, as opposed to the often proposed view of invasion being dependent on specific, and singular receptor-mediated endocytosis. This indicates that the endothelium not only has a critical role as a physical barrier against S. pneumoniae in the blood stream, but also in degrading S. pneumonia cells that have adhered to, and invaded the endothelial cells.
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24
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Luo Y, Zhan Y, Keen JH. Arf6 regulation of Gyrating-clathrin. Traffic 2012; 14:97-106. [PMID: 22998223 DOI: 10.1111/tra.12014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 09/19/2012] [Accepted: 09/21/2012] [Indexed: 11/29/2022]
Abstract
'Gyrating-' or 'G'-clathrin are coated endocytic structures located near peripheral sorting endosomes (SEs), which exhibit highly dynamic but localized movements when visualized by live-cell microscopy. They have been implicated in recycling of transferrin from the sorting endosome directly to the cell surface, but there is no information about their formation or regulation. We show here that G-clathrin comprise a minority of clathrin-coated structures in the cell periphery and are brefeldin A (BFA)-resistant. Arf6-GTP substantially increases G-clathrin levels, probably by lengthening coated bud lifetimes as suggested by photobleaching and photoactivation results, and an Arf6(Q67L)-GTP mutant bearing an internal GFP tag can be directly visualized in G-clathrin structures in live cells. Upon siRNA-mediated depletion of Arf6 or expression of Arf6(T27N), G-clathrin levels rise and are primarily Arf1-dependent, yet still BFA-resistant. However, BFA-sensitive increased G-clathrin levels are observed upon acute incubation with cytohesin inhibitor SecinH3, indicating a shift in GEF usage. Depletion of both Arf6 and Arf1 abolishes G-clathrin, and results in partial inhibition of fast transferrin recycling consistent with the latter's participation in this pathway. Collectively, these results demonstrate that the dynamics of G-clathrin primarily requires completion of the Arf6 guanine nucleotide cycle, but can be regulated by multiple Arf and GEF proteins, reflecting both overlapping mechanisms operative in their regulation and the complexity of processes involved in endosomal sorting.
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Affiliation(s)
- Yi Luo
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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25
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Keith DJ, Wolfrum K, Eshleman AJ, Janowsky A. Melittin initiates dopamine transporter internalization and recycling in transfected HEK-293 cells. Eur J Pharmacol 2012; 690:13-21. [PMID: 22683840 DOI: 10.1016/j.ejphar.2012.05.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 05/02/2012] [Accepted: 05/15/2012] [Indexed: 12/26/2022]
Abstract
The dopamine transporter removes the neurotransmitter from the synapse, regulating dopamine availability. The transporter can be internalized and its function is blocked by cocaine and other ligands. Melittin inhibits dopamine transporter function and causes internalization of the recombinant transporter in stably transfected HEK-293 cells, but the specific pathways for internalization and disposition of the transporter are unknown. Here we report that melittin treatment increased both transporter internalization and colocalization with clathrin, effects that were blocked by pretreatment with cocaine. Density gradient centrifugation revealed that melittin treatment caused the dopamine transporter to associate with a density fraction containing the early endosome marker Rab 5A. Confocal microscopy revealed that melittin treatment also increased transporter colocalization with Rab 5A and decreased colocalization with the late endosome marker Rab 7 and the recycling endosome marker Rab 11. Following 60 min of melittin treatment, the transporter was trafficked back to the membrane. By comparison, phorbol ester treatment increased transporter colocalization with early endosome antigen 1 and Rab 7 in a time-dependent manner. Cocaine treatment alone does not affect transporter trafficking in these cells. Results indicate multiple dopamine transporter internalization and recycling pathways that depend on transporter-ligand interactions and post-translational modifications.
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Affiliation(s)
- Dove J Keith
- Graduate Program in Neuroscience, VA Medical Center, Portland, OR 97239, USA
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26
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Gupta GS. P-Type Lectins: Cation-Dependent Mannose-6-Phosphate Receptor. ANIMAL LECTINS: FORM, FUNCTION AND CLINICAL APPLICATIONS 2012. [PMCID: PMC7121444 DOI: 10.1007/978-3-7091-1065-2_3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In eukaryotic cells, post-translational modification of secreted proteins and intracellular protein transport between organelles are ubiquitous features. One of the most studied systems is the N-linked glycosylation pathway in the synthesis of secreted glycoproteins (Schrag et al. 2003). The N-linked glycoproteins are subjected to diverse modifications and are transported through ER and Golgi apparatus to their final destinations in- and outside the cell. Incorporation of cargo glycoproteins into transport vesicles is mediated by transmembrane cargo receptors, which have been identified as intracellular lectins. For example, mannose 6-phosphate receptors (Ghosh et al. 2003) function as a cargo receptor for lysosomal proteins in the trans-Golgi network, whereas ERGIC-53 (Zhang et al. 2003) and its yeast orthologs Emp46/47p (Sato and Nakano 2002) are transport lectins for glycoproteins that are transported out of ER.
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Affiliation(s)
- G. S. Gupta
- Department of Biophysics, Punjab University, Chandigarh, India
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27
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Eden ER, Huang F, Sorkin A, Futter CE. The role of EGF receptor ubiquitination in regulating its intracellular traffic. Traffic 2012; 13:329-37. [PMID: 22017370 PMCID: PMC3261333 DOI: 10.1111/j.1600-0854.2011.01305.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2011] [Revised: 10/19/2011] [Accepted: 10/19/2011] [Indexed: 12/21/2022]
Abstract
Progression of activated EGF receptor (EGFR) through the endocytic pathway regulates EGFR signaling. Here we show that a non-ubiquitinated EGFR mutant, unable to bind the endosomal-sorting complex required for transport (ESCRT) component, Hrs, is not efficiently targeted onto intraluminal vesicles (ILVs) of multivesicular endosomes/bodies (MVBs). Moreover, ubiquitination and ESCRT engagement of activated EGFR are required for EGF-stimulated ILV formation. Non-ubiquitinated EGFRs enter clathrin-coated tubules emanating from MVBs and show enhanced recycling to the plasma membrane, compared to wild-type EGFR.
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Affiliation(s)
- Emily R Eden
- UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Fangtian Huang
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, 3500 Terrace Street, Pittsburgh, PA 15261 USA
| | - Alexander Sorkin
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, 3500 Terrace Street, Pittsburgh, PA 15261 USA
| | - Clare E Futter
- UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
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28
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Willenborg C, Jing J, Wu C, Matern H, Schaack J, Burden J, Prekeris R. Interaction between FIP5 and SNX18 regulates epithelial lumen formation. ACTA ACUST UNITED AC 2011; 195:71-86. [PMID: 21969467 PMCID: PMC3187708 DOI: 10.1083/jcb.201011112] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The Rab11 GTPase-binding protein FIP5 collaborates with the sorting nexin 18 to transport proteins to the apical surface and to tubulate membranes during epithelial apical lumen formation. During the morphogenesis of the epithelial lumen, apical proteins are thought to be transported via endocytic compartments to the site of the forming lumen, although the machinery mediating this transport remains to be elucidated. Rab11 GTPase and its binding protein, FIP5, are important regulators of polarized endocytic transport. In this study, we identify sorting nexin 18 as a novel FIP5-interacting protein and characterize the role of FIP5 and SNX18 in epithelial lumen morphogenesis. We show that FIP5 mediates the transport of apical proteins from apical endosomes to the apical plasma membrane and, along with SNX18, is required for the early stages of apical lumen formation. Furthermore, both proteins bind lipids, and FIP5 promotes the capacity of SNX18 to tubulate membranes, which implies a role for FIP5 and SNX18 in endocytic carrier formation and/or scission. In summary, the present findings support the hypothesis that this FIP5-SNX18 complex plays a pivotal role in the polarized transport of apical proteins during apical lumen initiation in epithelial cells.
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Affiliation(s)
- Carly Willenborg
- Department of Cell and Developmental Biology, University of Colorado Denver, Aurora, CO 80045, USA
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29
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Abstract
The surface of mucosal sites, such as the intestinal tract, are covered by epithelial cells. To protect the intestinal environment from invading pathogens and maintain homeostasis, the human body developed an exquisite acquired immune system, referred to as the mucosal immune system, in which epithelial cells and lymphocytes function cooperatively. The main player in this immune system is the polymeric immunoglobulins (pIgs), in particular dimeric IgA (dIgA). To exert its protective effect, dIgA produced in the lamina propria must be transported to the intestinal lumen across epithelial cells. This process is called transcytosis and is mediated by polymeric immunoglobulin receptor (pIgR), which is exclusively produced by intestinal epithelial cells (IECs). DIgA is captured by pIgR on the basolateral surface of IECs and transcytosed to the opposite side of IECs. The dIgA-pIgR complex is expressed on the apical surface of IECs and proteolytically cleaved to generate secretory IgA (SIgA). This review describes the current understanding and recent progress in this research field.
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Affiliation(s)
- Masatake Asano
- Department of Pathology, Nihon University School of Dentistry, Tokyo, Japan.
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30
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Grieve AG, Rabouille C. Golgi bypass: skirting around the heart of classical secretion. Cold Spring Harb Perspect Biol 2011; 3:cshperspect.a005298. [PMID: 21441587 DOI: 10.1101/cshperspect.a005298] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Classical secretion consists of the delivery of transmembrane and soluble proteins to the plasma membrane and the extracellular medium, respectively, and is mediated by the organelles of the secretory pathway, the Endoplasmic Reticulum (ER), the ER exit sites, and the Golgi, as described by the Nobel Prize winner George Palade (Palade 1975). At the center of this transport route, the Golgi stack has a major role in modifying, processing, sorting, and dispatching newly synthesized proteins to their final destinations. More recently, however, it has become clear that an increasing number of transmembrane proteins reach the plasma membrane unconventionally, either by exiting the ER in non-COPII vesicles or by bypassing the Golgi. Here, we discuss the evidence for Golgi bypass and the possible physiological benefits of it. Intriguingly, at least during Drosophila development, Golgi bypass seems to be mediated by a Golgi protein, dGRASP, which is found ectopically localized to the plasma membrane.
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Affiliation(s)
- Adam G Grieve
- Cell Microscopy Centre, Department of Cell Biology, University Medical Center Utrecht, The Netherlands
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31
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Recycling endosomes in apical plasma membrane domain formation and epithelial cell polarity. Trends Cell Biol 2010; 20:618-26. [PMID: 20833047 DOI: 10.1016/j.tcb.2010.08.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 08/05/2010] [Accepted: 08/06/2010] [Indexed: 01/24/2023]
Abstract
Recycling endosomes have taken central stage in the intracellular sorting and polarized trafficking of apical and basolateral plasma membrane components. Molecular players in the underlying mechanisms are now emerging, including small GTPases, class V myosins and adaptor proteins. In particular, defects in the expression or function of these recycling endosome-associated and endosome-regulating proteins have been implicated in cell surface polarity defects and diseases, including microvillus inclusion disease, arthrogryposis-renal dysfunction-cholestasis syndrome, and virus susceptibility. Key findings are that recycling endosomes recruit and deliver core polarity proteins to lateral cell surfaces and initiate the biogenesis of apical plasma membrane domains and epithelial cell polarity. Here, we review recent data that implicate recycling endosomes in the establishment and maintenance of epithelial cell polarity.
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32
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Membrane contacts between endosomes and ER provide sites for PTP1B-epidermal growth factor receptor interaction. Nat Cell Biol 2010; 12:267-72. [PMID: 20118922 DOI: 10.1038/ncb2026] [Citation(s) in RCA: 244] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Accepted: 01/17/2009] [Indexed: 01/13/2023]
Abstract
The epidermal growth factor receptor (EGFR) is a critical determinator of cell fate. Signalling from this receptor tyrosine kinase is spatially regulated by progression through the endocytic pathway, governing receptor half-life and accessibility to signalling proteins and phosphatases. Endocytosis of EGFR is required for interaction with the protein tyrosine phosphatase PTP1B (ref. 1), which localizes to the cytoplasmic face of the endoplasmic reticulum (ER), raising the question of how PTP1B comes into contact with endosomal EGFR. We show that EGFR-PTP1B interaction occurs by means of direct membrane contacts between the perimeter membrane of multivesicular bodies (MVBs) and the ER. The population of EGFR interacting with PTP1B is the same population that undergo ESCRT-mediated (endosomal sorting complex required for transport) sorting within MVBs, and PTP1B activity promotes the sequestration of EGFR on to MVB internal vesicles. Membrane contacts between endosomes and the ER form in both the presence and absence of stimulation by EGF. Thus membrane contacts between endosomes and the ER may represent a global mechanism for direct interaction between proteins on these two organelles.
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Maritzen T, Schmidt MR, Kukhtina V, Higman VA, Strauss H, Volkmer R, Oschkinat H, Dotti CG, Haucke V. A novel subtype of AP-1-binding motif within the palmitoylated trans-Golgi network/endosomal accessory protein Gadkin/gamma-BAR. J Biol Chem 2009; 285:4074-4086. [PMID: 19965873 DOI: 10.1074/jbc.m109.049197] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Membrane traffic between the trans-Golgi network (TGN) and endosomes is mediated in part by the assembly of clathrin-AP-1 adaptor complex-coated vesicles. This process involves multiple accessory proteins that directly bind to the ear domain of AP-1gamma via degenerate peptide motifs that conform to the consensus sequence diameterG(P/D/E)(diameter/L/M) (with diameter being a large hydrophobic amino acid). Recently, gamma-BAR (hereafter referred to as Gadkin for reasons explained below) has been identified as a novel AP-1 recruitment factor involved in AP-1-dependent endosomal trafficking of lysosomal enzymes. How precisely Gadkin interacts with membranes and with AP-1gamma has remained unclear. Here we show that Gadkin is an S-palmitoylated peripheral membrane protein that lacks stable tertiary structure. S-Palmitoylation is required for the recruitment of Gadkin to TGN/endosomal membranes but not for binding to AP-1. Furthermore, we identify a novel subtype of AP-1-binding motif within Gadkin that specifically associates with the gamma1-adaptin ear domain. Mutational inactivation of this novel type of motif, either alone or in combination with three more conventional AP-1gamma binding peptides, causes Gadkin to mislocalize to the plasma membrane and interferes with its ability to render AP-1 brefeldin A-resistant, indicating its physiological importance. Our studies thus unravel the molecular basis for Gadkin-mediated AP-1 recruitment to TGN/endosomal membranes and identify a novel subtype of the AP-1-binding motif.
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Affiliation(s)
- Tanja Maritzen
- From the Institute of Chemistry and Biochemistry, Department of Membrane Biochemistry, Freie Universität and Charité-Universitätsmedizin Berlin, Takustrasse 6, 14195 Berlin, Germany
| | - Michael R Schmidt
- From the Institute of Chemistry and Biochemistry, Department of Membrane Biochemistry, Freie Universität and Charité-Universitätsmedizin Berlin, Takustrasse 6, 14195 Berlin, Germany
| | - Viktoria Kukhtina
- From the Institute of Chemistry and Biochemistry, Department of Membrane Biochemistry, Freie Universität and Charité-Universitätsmedizin Berlin, Takustrasse 6, 14195 Berlin, Germany
| | - Victoria A Higman
- the Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Holger Strauss
- the Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Rudolf Volkmer
- the Institut für Medizinische Immunologie, Charité-Universitätsmedizin Berlin, Hessische Strasse 3-4, 10115 Berlin, Germany
| | - Hartmut Oschkinat
- the Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Carlos G Dotti
- the Vlanders Institute for Biotechnology, Molecular & Developmental Genetics Program and Department of Human Genetics, University of Leuven Medical School, Herestraat 49, 3000 Leuven, Belgium, and
| | - Volker Haucke
- From the Institute of Chemistry and Biochemistry, Department of Membrane Biochemistry, Freie Universität and Charité-Universitätsmedizin Berlin, Takustrasse 6, 14195 Berlin, Germany; the Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, 13125 Berlin, Germany.
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Gonzalez A, Rodriguez-Boulan E. Clathrin and AP1B: key roles in basolateral trafficking through trans-endosomal routes. FEBS Lett 2009; 583:3784-95. [PMID: 19854182 DOI: 10.1016/j.febslet.2009.10.050] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 10/15/2009] [Accepted: 10/20/2009] [Indexed: 12/12/2022]
Abstract
Research following introduction of the MDCK model system to study epithelial polarity (1978) led to an initial paradigm that posited independent roles of the trans Golgi network (TGN) and recycling endosomes (RE) in the generation of, respectively, biosynthetic and recycling routes of plasma membrane (PM) proteins to apical and basolateral PM domains. This model dominated the field for 20 years. However, studies over the past decade and the discovery of the involvement of clathrin and clathrin adaptors in protein trafficking to the basolateral PM has led to a new paradigm. TGN and RE are now believed to cooperate closely in both biosynthetic and recycling trafficking routes. Here, we critically review these recent advances and the questions that remain unanswered.
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Affiliation(s)
- Alfonso Gonzalez
- Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, Centro de Regulación Celular y Patología and Centro de Envejecimiento y Regeneración, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, 6510260 Santiago, Chile.
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35
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Murai N, Miyake Y, Tsuzuki S, Inouye K, Fushiki T. Involvement of the cytoplasmic juxtamembrane region of matriptase in its exclusive localization to the basolateral membrane domain of Madin-Darby canine kidney epithelial cells. Cytotechnology 2009; 59:169-76. [PMID: 19557537 DOI: 10.1007/s10616-009-9205-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2009] [Accepted: 06/07/2009] [Indexed: 10/20/2022] Open
Abstract
Matriptase is a type II transmembrane serine protease. This protease is strongly expressed in simple epithelial cells such as enterocytes and kidney tubular cells in which the plasma membranes are separated into apical and basolateral domains. Although matriptase was found previously to occur exclusively on the basolateral membrane of enterocytes, the underlying mechanism of localization is unclear. In the present study, a full-length rat matriptase and a chimera consisting of the cytoplasmic and transmembrane regions of the protease and green fluorescent protein (designated as 1-86GFP) were found to localize exclusively to the basolateral membrane domain when expressed in Madin-Darby canine kidney epithelial cells. Mutagenesis analysis of 1-86GFP revealed that the matriptase cytoplasmic juxtamembrane amino acid residues (Lys45, Val47, and Arg50) play a role in mediating the localization in the cells. This study provides the first evidence that matriptase carries information for its localization in simple epithelia.
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Affiliation(s)
- Nobuhito Murai
- Laboratory of Nutrition Chemistry, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
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36
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Truschel ST, Simoes S, Setty SRG, Harper DC, Tenza D, Thomas PC, Herman KE, Sackett SD, Cowan DC, Theos AC, Raposo G, Marks MS. ESCRT-I function is required for Tyrp1 transport from early endosomes to the melanosome limiting membrane. Traffic 2009; 10:1318-36. [PMID: 19624486 DOI: 10.1111/j.1600-0854.2009.00955.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Melanosomes are lysosome-related organelles that coexist with lysosomes within melanocytes. The pathways by which melanosomal proteins are diverted from endocytic organelles toward melanosomes are incompletely defined. In melanocytes from mouse models of Hermansky-Pudlak syndrome that lack BLOC-1, melanosomal proteins such as tyrosinase-related protein 1 (Tyrp1) accumulate in early endosomes. Whether this accumulation represents an anomalous pathway or an arrested normal intermediate in melanosome protein trafficking is not clear. Here, we show that early endosomes are requisite intermediates in the trafficking of Tyrp1 from the Golgi to late stage melanosomes in normal melanocytic cells. Kinetic analyses show that very little newly synthesized Tyrp1 traverses the cell surface and that internalized Tyrp1 is inefficiently sorted to melanosomes. Nevertheless, nearly all Tyrp1 traverse early endosomes since it becomes trapped within enlarged, modified endosomes upon overexpression of Hrs. Although Tyrp1 localization is not affected by Hrs depletion, depletion of the ESCRT-I component, Tsg101, or inhibition of ESCRT function by dominant-negative approaches results in a dramatic redistribution of Tyrp1 to aberrant endosomal membranes that are largely distinct from those harboring traditional ESCRT-dependent, ubiquitylated cargoes such as MART-1. The lysosomal protein content of some of these membranes and the lack of Tyrp1 recycling to the plasma membrane in Tsg101-depleted cells suggests that ESCRT-I functions downstream of BLOC-1. Our data delineate a novel pathway for Tyrp1 trafficking and illustrate a requirement for ESCRT-I function in controlling protein sorting from vacuolar endosomes to the limiting membrane of a lysosome-related organelle.
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Affiliation(s)
- Steven T Truschel
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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37
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Rojas R, van Vlijmen T, Mardones GA, Prabhu Y, Rojas AL, Mohammed S, Heck AJR, Raposo G, van der Sluijs P, Bonifacino JS. Regulation of retromer recruitment to endosomes by sequential action of Rab5 and Rab7. ACTA ACUST UNITED AC 2008; 183:513-26. [PMID: 18981234 PMCID: PMC2575791 DOI: 10.1083/jcb.200804048] [Citation(s) in RCA: 390] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The retromer complex mediates retrograde transport of transmembrane cargo from endosomes to the trans-Golgi network (TGN). Mammalian retromer is composed of a sorting nexin (SNX) dimer that binds to phosphatidylinositol 3-phosphate–enriched endosomal membranes and a vacuolar protein sorting (Vps) 26/29/35 trimer that participates in cargo recognition. The mammalian SNX dimer is necessary but not sufficient for recruitment of the Vps26/29/35 trimer to membranes. In this study, we demonstrate that the guanosine triphosphatase Rab7 contributes to this recruitment. The Vps26/29/35 trimer specifically binds to Rab7–guanosine triphosphate (GTP) and localizes to Rab7-containing endosomal domains. Interference with Rab7 function causes dissociation of the Vps26/29/35 trimer but not the SNX dimer from membranes. This blocks retrieval of mannose 6-phosphate receptors to the TGN and impairs cathepsin D sorting. Rab5-GTP does not bind to the Vps26/29/35 trimer, but perturbation of Rab5 function causes dissociation of both the SNX and Vps26/29/35 components from membranes through inhibition of a pathway involving phosphatidylinositol 3-kinase. These findings demonstrate that Rab5 and Rab7 act in concert to regulate retromer recruitment to endosomes.
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Affiliation(s)
- Raul Rojas
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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Schonteich E, Wilson GM, Burden J, Hopkins CR, Anderson K, Goldenring JR, Prekeris R. The Rip11/Rab11-FIP5 and kinesin II complex regulates endocytic protein recycling. J Cell Sci 2008; 121:3824-33. [PMID: 18957512 DOI: 10.1242/jcs.032441] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Sorting and recycling of endocytosed proteins are required for proper cellular function and growth. Internalized receptors either follow a fast constitutive recycling pathway, returning to the cell surface directly from the early endosomes, or a slow pathway that involves transport via perinuclear recycling endosomes. Slow recycling pathways are thought to play a key role in directing recycling proteins to specific locations on cell surfaces, such as the leading edges of motile cells. These pathways are regulated by various Rab GTPases, such as Rab4 and Rab11. Here we characterize the role of Rip11/FIP5, a known Rab11-binding protein, in regulating endocytic recycling. We use a combination of electron and fluorescent microscopy with siRNA-based protein knockdown to show that Rip11/FIP5 is present at the peripheral endosomes, where it regulates the sorting of internalized receptors to a slow recycling pathway. We also identify kinesin II as a Rip11/FIP5-binding protein and show that it is required for directing endocytosed proteins into the same recycling pathway. Thus, we propose that the Rip11/FIP5-kinesin-II complex has a key role in the routing of internalized receptors through the perinuclear recycling endosomes.
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Affiliation(s)
- Eric Schonteich
- Department of Cellular and Developmental Biology, School of Medicine, University of Colorado Health Sciences Center, 12801 E. 17th Avenue, Aurora, CO 80045, USA
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39
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Zhao Y, Keen JH. Gyrating clathrin: highly dynamic clathrin structures involved in rapid receptor recycling. Traffic 2008; 9:2253-64. [PMID: 18817526 DOI: 10.1111/j.1600-0854.2008.00819.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We report here detection of novel intracellular clathrin-coated structures revealed by continuous high-speed imaging of cells expressing green fluorescent protein fusion proteins. These structures, which we operationally term 'gyrating clathrin' (G-clathrin), are characterized by localized but extremely rapid movement, leading to the hypothesis that they are coated buds on waving membrane tubules. G-clathrin structures have structurally and functionally distinct features. They lack detectable adaptor proteins AP-1 and AP-2 but contain GGA1 [Golgi-localized, gamma-ear-containing, Arf (ADP-ribosylation factor)-binding protein] as well as the cation-dependent mannose-6-phosphate receptor. While they accumulate internalized transferrin (Tf), they do not contain detectable levels of cargos targeted for the late endosome/lysosome pathway such as EGF and dextran. Pulse-chase studies indicate that Tf appears in G-clathrin structures in the cell periphery after sorting endosomes (SEs), but before filling of the perinuclear endocytic recycling compartment. Furthermore, the inhibitors LY294002 and wortmannin, which inhibit direct recycling of Tf from SEs to the plasma membrane, also block its appearance in G-clathrin. These observations suggest that peripheral G-clathrin contributes to rapid recycling, a kinetically defined compartment that has largely eluded structural identification. More generally, the rapid continuous live cell imaging reported here reveals new aspects of membrane trafficking.
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Affiliation(s)
- Yanqiu Zhao
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 S. 10th Street, BLSB/915, Philadelphia, PA 19107, USA
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40
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Hasler U, Nunes P, Bouley R, Lu HAJ, Matsuzaki T, Brown D. Acute hypertonicity alters aquaporin-2 trafficking and induces a MAPK-dependent accumulation at the plasma membrane of renal epithelial cells. J Biol Chem 2008; 283:26643-61. [PMID: 18664568 DOI: 10.1074/jbc.m801071200] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The unique phenotype of renal medullary cells allows them to survive and functionally adapt to changes of interstitial osmolality/tonicity. We investigated the effects of acute hypertonic challenge on AQP2 (aquaporin-2) water channel trafficking. In the absence of vasopressin, hypertonicity alone induced rapid (<10 min) plasma membrane accumulation of AQP2 in rat kidney collecting duct principal cells in situ, and in several kidney epithelial lines. Confocal microscopy revealed that AQP2 also accumulated in the trans-Golgi network (TGN) following hypertonic challenge. AQP2 mutants that mimic the Ser(256)-phosphorylated and -nonphosphorylated state accumulated at the cell surface and TGN, respectively. Hypertonicity did not induce a change in cytosolic cAMP concentration, but inhibition of either calmodulin or cAMP-dependent protein kinase A activity blunted the hypertonicity-induced increase of AQP2 cell surface expression. Hypertonicity increased p38, ERK1/2, and JNK MAPK activity. Inhibiting MAPK activity abolished hypertonicity-induced accumulation of AQP2 at the cell surface but did not affect either vasopressin-dependent AQP2 trafficking or hypertonicity-induced AQP2 accumulation in the TGN. Finally, increased AQP2 cell surface expression induced by hypertonicity largely resulted from a reduction in endocytosis but not from an increase in exocytosis. These data indicate that acute hypertonicity profoundly alters AQP2 trafficking and that hypertonicity-induced AQP2 accumulation at the cell surface depends on MAP kinase activity. This may have important implications on adaptational processes governing transcellular water flux and/or cell survival under extreme conditions of hypertonicity.
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Affiliation(s)
- Udo Hasler
- Massachusetts General Hospital Center for Systems Biology, Program in Membrane Biology and Nephrology Division, Massachusetts General Hospital, Boston, Massachusetts 02114-2790, USA.
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41
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Ceresa BP, Vanlandingham PA. Molecular Mechanisms that Regulate Epidermal Growth Factor Receptor Inactivation. Clin Med Oncol 2008; 2:47-61. [PMID: 21892266 PMCID: PMC3161635 DOI: 10.4137/cmo.s498] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The Epidermal Growth Factor Receptor (EGFR) is the prototypical receptor tyrosine kinase (RTK). These cell surface receptors are integral membrane proteins that bind ligands on their extracellular domain and relay that information to within the cell. The activated EGFR regulates diverse cell fates such as growth, proliferation, differentiation, migration, and apoptosis. These signaling properties are important for the appropriate development and maintenance of an organism. However, when inappropriately controlled, due to EGFR overexpression or hyperactivation, these signaling events are characteristic of many cancers. It remains unclear whether the uncontrolled EGFR activity leads to cell transformation or is a consequence of cell transformation. Regardless of the cause, increased EGFR activity serves both as a biomarker in the diagnosis of some cancers and is a molecular target for anti-cancer therapies. The promising results with current anti-EGFR therapies suggest that the receptor is a viable molecular target for a limited number of applications. However, to become an effective therapeutic target for other cancers that have elevated levels of EGFR activity, current approaches for inhibiting EGFR signaling will need to be refined. Here we describe the molecular mechanisms that regulate EGFR inactivation and discuss their potential as therapeutic targets for inhibiting EGFR signaling.
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Affiliation(s)
- Brian P Ceresa
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190
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42
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Duffield A, Caplan MJ, Muth TR. Chapter 4 Protein Trafficking in Polarized Cells. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 270:145-79. [DOI: 10.1016/s1937-6448(08)01404-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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43
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Mari M, Bujny MV, Zeuschner D, Geerts WJC, Griffith J, Petersen CM, Cullen PJ, Klumperman J, Geuze HJ. SNX1 defines an early endosomal recycling exit for sortilin and mannose 6-phosphate receptors. Traffic 2007; 9:380-93. [PMID: 18088323 DOI: 10.1111/j.1600-0854.2007.00686.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mannose-6-phosphate receptors (MPRs) transport lysosomal hydrolases from the trans Golgi network (TGN) to endosomes. Recently, the multi-ligand receptor sortilin has also been implicated in this transport, but the transport carriers involved herein have not been identified. By quantitative immuno-electron microscopy, we localized endogenous sortilin of HepG2 cells predominantly to the TGN and endosomes. In the TGN, sortilin colocalized with MPRs in the same clathrin-coated vesicles. In endosomes, sortilin and MPRs concentrated in sorting nexin 1 (SNX1)-positive buds and vesicles. SNX1 depletion by small interfering RNA resulted in decreased pools of sortilin in the TGN and an increase in lysosomal degradation. These data indicate that sortilin and MPRs recycle to the TGN in SNX1-dependent carriers, which we named endosome-to-TGN transport carriers (ETCs). Notably, ETCs emerge from early endosomes (EE), lack recycling plasma membrane proteins and by three-dimensional electron tomography exhibit unique structural features. Hence, ETCs are distinct from hitherto described EE-derived membranes involved in recycling. Our data emphasize an important role of EEs in recycling to the TGN and indicate that different, specialized exit events occur on the same EE vacuole.
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Affiliation(s)
- Muriel Mari
- Cell Microscopy Center, Department of Cell Biology, Institute of Biomembranes, University Medical Centre (UMC) Utrecht, AZU Rm G02.525, 3584 CX Utrecht, The Netherlands
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Cancino J, Torrealba C, Soza A, Yuseff MI, Gravotta D, Henklein P, Rodriguez-Boulan E, González A. Antibody to AP1B adaptor blocks biosynthetic and recycling routes of basolateral proteins at recycling endosomes. Mol Biol Cell 2007; 18:4872-84. [PMID: 17881725 PMCID: PMC2096610 DOI: 10.1091/mbc.e07-06-0563] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Accepted: 09/11/2007] [Indexed: 01/03/2023] Open
Abstract
The epithelial-specific adaptor AP1B sorts basolateral plasma membrane (PM) proteins in both biosynthetic and recycling routes, but the site where it carries out this function remains incompletely defined. Here, we have investigated this topic in Fischer rat thyroid (FRT) epithelial cells using an antibody against the medium subunit micro1B. This antibody was suitable for immunofluorescence and blocked the function of AP1B in these cells. The antibody blocked the basolateral recycling of two basolateral PM markers, Transferrin receptor (TfR) and LDL receptor (LDLR), in a perinuclear compartment with marker and functional characteristics of recycling endosomes (RE). Live imaging experiments demonstrated that in the presence of the antibody two newly synthesized GFP-tagged basolateral proteins (vesicular stomatitis virus G [VSVG] protein and TfR) exited the trans-Golgi network (TGN) normally but became blocked at the RE within 3-5 min. By contrast, the antibody did not block trafficking of green fluorescent protein (GFP)-LDLR from the TGN to the PM but stopped its recycling after internalization into RE in approximately 45 min. Our experiments conclusively demonstrate that 1) AP1B functions exclusively at RE; 2) TGN-to-RE transport is very fast and selective and is mediated by adaptors different from AP1B; and 3) the TGN and AP1B-containing RE cooperate in biosynthetic basolateral sorting.
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Affiliation(s)
- Jorge Cancino
- *Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, and Centro de Regulación Celular y Patología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, 6510260 Santiago, Chile
- Millennium Institute for Fundamental and Applied Biology, 7780344 Santiago, Chile
| | - Carolina Torrealba
- *Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, and Centro de Regulación Celular y Patología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, 6510260 Santiago, Chile
- Millennium Institute for Fundamental and Applied Biology, 7780344 Santiago, Chile
| | - Andrea Soza
- *Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, and Centro de Regulación Celular y Patología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, 6510260 Santiago, Chile
- Millennium Institute for Fundamental and Applied Biology, 7780344 Santiago, Chile
| | - María Isabel Yuseff
- *Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, and Centro de Regulación Celular y Patología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, 6510260 Santiago, Chile
- Millennium Institute for Fundamental and Applied Biology, 7780344 Santiago, Chile
| | - Diego Gravotta
- Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY 10021
| | - Peter Henklein
- Institute of Biochemistry Faculty of Medicine, Humboldt University, 10117 Berlin, Germany; and
| | - Enrique Rodriguez-Boulan
- Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY 10021
| | - Alfonso González
- *Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, and Centro de Regulación Celular y Patología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, 6510260 Santiago, Chile
- Millennium Institute for Fundamental and Applied Biology, 7780344 Santiago, Chile
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45
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Norouziyan F, Shen WC, Hamm-Alvarez SF. Tyrphostin A8 stimulates a novel trafficking pathway of apically endocytosed transferrin through Rab11-enriched compartments in Caco-2 cells. Am J Physiol Cell Physiol 2007; 294:C7-21. [PMID: 17959726 DOI: 10.1152/ajpcell.00372.2006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The potential application of transferrin receptors as delivery vehicles for transport of macromolecular drugs across intestinal epithelial cells is limited by several factors, including the low level of transferrin receptor-mediated transcytosis, particularly in the apical-to-basolateral direction. The GTPase inhibitor, AG10 (tyrphostin A8), has been shown previously to increase the apical-to-basolateral transcytosis of transferrin in Caco-2 cells. However, the mechanism of the increased transcytosis has not been established. In this report, the effect of AG10 on the trafficking of endocytosed transferrin among different endosomal compartments as well as the involvement of Rab11 in the intracellular trafficking of transferrin was investigated. Confocal microscopy studies showed a high level of colocalization of FITC-transferrin with Rab5 and Rab11 in Caco-2 cells pulsed at 16 degrees C and 37 degrees C, which indicated the presence of apically endocytosed FITC-transferrin in early endosomes and apical recycling endosomes at 16 degrees C and 37 degrees C, respectively. The effect of AG10 on the accumulation of transferrin within different endosomal compartment was studied, and an increase in the transcytosis and recycling of internalized (125)I-labeled transferrin, as well as a decrease in cell-associated (125)I-labeled transferrin, was observed in AG10-treated Caco-2 cells pulsed at 37 degrees C for 30 min and chased for 30 min. Moreover, confocal microscopy showed that FITC-transferrin exhibited an increased level of colocalization with Rab11, but not with Rab5, in the presence of AG10. These results suggest an effect of AG10 on the later steps of transferrin receptor trafficking, which are involved in subsequent recycling, and possibly transcytosis, of endocytosed transferrin in Caco-2 cells.
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Affiliation(s)
- Fariba Norouziyan
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, California 90033, USA
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46
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Braun V, Deschamps C, Raposo G, Benaroch P, Benmerah A, Chavrier P, Niedergang F. AP-1 and ARF1 control endosomal dynamics at sites of FcR mediated phagocytosis. Mol Biol Cell 2007; 18:4921-31. [PMID: 17914058 PMCID: PMC2096587 DOI: 10.1091/mbc.e07-04-0392] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Phagocytosis, the mechanism of ingestion of large material and microorganisms, relies on actin polymerization and on the focal delivery of intracellular endocytic compartments. The molecular mechanisms involved in the formation and delivery of the endocytic vesicles that are recruited at sites of phagocytosis are not well characterized. Here we show that adaptor protein (AP)-1 but not AP-2 clathrin adaptor complexes are recruited early below the sites of particle attachment and are required for efficient receptor-mediated phagocytosis in murine macrophages. Clathrin, however, is not recruited with the AP complexes. We further show that the recruitment of AP-1-positive structures at sites of phagocytosis is regulated by the GTP-binding protein ARF1 but is not sensitive to brefeldin A. Furthermore, AP-1 depletion leads to increased surface levels of TNF-alpha, a cargo known to traffic through the endosomes to the plasma membrane upon stimulation of the macrophages. Together, our results support a clathrin-independent role for AP complexes in endosomal dynamics in macrophages by retaining some cargo proteins, a process important for membrane remodeling during phagocytosis.
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Affiliation(s)
- Virginie Braun
- *Institut Curie, Centre de Recherche, Paris, F-75248 France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144, Paris, F-75248 France
| | - Chantal Deschamps
- Institut Cochin, Université Paris Descartes, Centre National de la Recherche Scientifique (Unité Mixte de Recherche 8104), F-75014 Paris, France
- Institut National de la Santé et de la Recherche Médicale, U567, F-75014 Paris, France; and
| | - Graça Raposo
- *Institut Curie, Centre de Recherche, Paris, F-75248 France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144, Paris, F-75248 France
| | - Philippe Benaroch
- *Institut Curie, Centre de Recherche, Paris, F-75248 France
- Institut National de la Santé et de la Recherche Médicale U653, F-75248 Paris, France
| | - Alexandre Benmerah
- Institut Cochin, Université Paris Descartes, Centre National de la Recherche Scientifique (Unité Mixte de Recherche 8104), F-75014 Paris, France
- Institut National de la Santé et de la Recherche Médicale, U567, F-75014 Paris, France; and
| | - Philippe Chavrier
- *Institut Curie, Centre de Recherche, Paris, F-75248 France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144, Paris, F-75248 France
| | - Florence Niedergang
- Institut Cochin, Université Paris Descartes, Centre National de la Recherche Scientifique (Unité Mixte de Recherche 8104), F-75014 Paris, France
- Institut National de la Santé et de la Recherche Médicale, U567, F-75014 Paris, France; and
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47
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Kametaka S, Moriyama K, Burgos PV, Eisenberg E, Greene LE, Mattera R, Bonifacino JS. Canonical interaction of cyclin G associated kinase with adaptor protein 1 regulates lysosomal enzyme sorting. Mol Biol Cell 2007; 18:2991-3001. [PMID: 17538018 PMCID: PMC1949374 DOI: 10.1091/mbc.e06-12-1162] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The adaptor protein 1 (AP1) complex is a heterotetramer that participates in cargo sorting into clathrin-coated vesicles at the trans-Golgi network (TGN) and endosomes. The gamma subunit of AP1 possesses a C-terminal "ear" domain that recruits a cohort of accessory proteins through recognition of a shared canonical motif, PsiG[PDE][PsiLM] (where Psi is an aromatic residue). The physiological relevance of these ear-motif interactions, however, remains to be demonstrated. Here we report that the cyclin G-associated kinase (GAK) has two sequences fitting this motif, FGPL and FGEF, which mediate binding to the AP1-gamma-ear domain in vitro. Mutation of both gamma-ear-binding sequences or depletion of AP1-gamma by RNA interference (RNAi) decreases the association of GAK with the TGN in vivo. Depletion of GAK by RNAi impairs the sorting of the acid hydrolase, cathepsin D, to lysosomes. Importantly, expression of RNAi-resistant GAK restores the lysosomal sorting of cathepsin D in cells depleted of endogenous GAK, whereas expression of a similar construct bearing mutations in both gamma-ear-binding sequences fails to correct the sorting defect. Thus, interactions between the PsiG[PDE][PsiLM]-motif sequences in GAK and the AP1-gamma-ear domain are critical for the recruitment of GAK to the TGN and the function of GAK in lysosomal enzyme sorting.
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Affiliation(s)
- Satoshi Kametaka
- *Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, and
| | - Kengo Moriyama
- *Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, and
| | - Patricia V. Burgos
- *Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, and
| | - Evan Eisenberg
- Laboratory of Cell Biology, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Lois E. Greene
- Laboratory of Cell Biology, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Rafael Mattera
- *Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, and
| | - Juan S. Bonifacino
- *Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, and
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48
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Henderson DM, Conner SD. A novel AAK1 splice variant functions at multiple steps of the endocytic pathway. Mol Biol Cell 2007; 18:2698-706. [PMID: 17494869 PMCID: PMC1924820 DOI: 10.1091/mbc.e06-09-0831] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Phosphorylation is a critical step in regulating receptor transport through the endocytic pathway. AAK1 is a serine/threonine kinase that is thought to coordinate the recruitment of AP-2 to receptors containing tyrosine-based internalization motifs by phosphorylating the micro2 subunit. Here we have identified a long form of AAK1 (AAK1L) that contains an extended C-terminus that encodes an additional clathrin-binding domain (CBD2) consisting of multiple low-affinity interaction motifs. Protein interaction studies demonstrate that AAK1L CBD2 directly binds clathrin. However, in vitro kinase assays reveal little difference between AAK1 isoforms in their basal or clathrin-stimulated kinase activity toward the AP-2 micro2 subunit. However, overexpression of AAK1L CBD2 impairs transferrin endocytosis, confirming an endocytic role for AAK1. Surprisingly, CBD2 overexpression or AAK1 depletion by RNA interference significantly impairs transferrin recycling from the early/sorting endosome. These observations suggest that AAK1 functions at multiple steps of the endosomal pathway by regulating transferrin internalization and its rapid recycling back to the plasma membrane from early/sorting endosome.
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Affiliation(s)
- Davin M. Henderson
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455
| | - Sean D. Conner
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455
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49
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Thompson A, Nessler R, Wisco D, Anderson E, Winckler B, Sheff D. Recycling endosomes of polarized epithelial cells actively sort apical and basolateral cargos into separate subdomains. Mol Biol Cell 2007; 18:2687-97. [PMID: 17494872 PMCID: PMC1924834 DOI: 10.1091/mbc.e05-09-0873] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The plasma membranes of epithelial cells plasma membranes contain distinct apical and basolateral domains that are critical for their polarized functions. However, both domains are continuously internalized, with proteins and lipids from each intermixing in supranuclear recycling endosomes (REs). To maintain polarity, REs must faithfully recycle membrane proteins back to the correct plasma membrane domains. We examined sorting within REs and found that apical and basolateral proteins were laterally segregated into subdomains of individual REs. Subdomains were absent in unpolarized cells and developed along with polarization. Subdomains were formed by an active sorting process within REs, which precedes the formation of AP-1B-dependent basolateral transport vesicles. Both the formation of subdomains and the fidelity of basolateral trafficking were dependent on PI3 kinase activity. This suggests that subdomain and transport vesicle formation occur as separate sorting steps and that both processes may contribute to sorting fidelity.
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Affiliation(s)
| | - Randy Nessler
- Imaging Core Facility, University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | - Dolora Wisco
- Department of Neuroscience, University of Virginia Medical School, Charlottesville, VA 22908; and
| | - Eric Anderson
- Department of Cell Biology, Yale School of Medicine and Ludwig Institute for Cancer Research, New Haven, CT 06520
| | - Bettina Winckler
- Department of Neuroscience, University of Virginia Medical School, Charlottesville, VA 22908; and
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50
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Wallrabe H, Bonamy G, Periasamy A, Barroso M. Receptor complexes cotransported via polarized endocytic pathways form clusters with distinct organizations. Mol Biol Cell 2007; 18:2226-43. [PMID: 17409357 PMCID: PMC1877110 DOI: 10.1091/mbc.e06-08-0700] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Previously, FRET confocal microscopy has shown that polymeric IgA-receptor (pIgA-R) is distributed in a clustered manner in apical endosomes. To test whether different membrane-bound components form clusters during membrane trafficking, live-cell quantitative FRET was used to characterize the organization of pIgA-R and transferrin receptor (TFR) in endocytic membranes of polarized MDCK cells upon internalization of donor- and acceptor-labeled ligands. We show that pIgA-R and TFR complexes form increasingly organized clusters during cotransport from basolateral to perinuclear endosomes. The organization of these receptor clusters in basolateral versus perinuclear/apical endosomes is significantly different; the former showing a mixed random/clustered distribution while the latter highly organized clusters. Our results indicate that although both perinuclear and apical endosomes comprise pIgA-R and TFR clusters, their E% levels are significantly different suggesting that these receptors are packed into clusters in a distinct manner. The quantitative FRET-based assay presented here suggests that different receptor complexes form clusters, with diverse levels of organization, while being cotransported via the polarized endocytic pathways.
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Affiliation(s)
- H Wallrabe
- Department of Biology, W. M. Keck Center for Cellular Imaging, University of Virginia, Charlottesville, VA 22904, USA
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