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Greig J, Bates GT, Yin DI, Briant K, Simonetti B, Cullen PJ, Brodsky FM. CHC22 clathrin recruitment to the early secretory pathway requires two-site interaction with SNX5 and p115. EMBO J 2024; 43:4298-4323. [PMID: 39160272 PMCID: PMC11445476 DOI: 10.1038/s44318-024-00198-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 07/15/2024] [Accepted: 07/17/2024] [Indexed: 08/21/2024] Open
Abstract
The two clathrin isoforms, CHC17 and CHC22, mediate separate intracellular transport routes. CHC17 performs endocytosis and housekeeping membrane traffic in all cells. CHC22, expressed most highly in skeletal muscle, shuttles the glucose transporter GLUT4 from the ERGIC (endoplasmic-reticulum-to-Golgi intermediate compartment) directly to an intracellular GLUT4 storage compartment (GSC), from where GLUT4 can be mobilized to the plasma membrane by insulin. Here, molecular determinants distinguishing CHC22 from CHC17 trafficking are defined. We show that the C-terminal trimerization domain of CHC22 interacts with SNX5, which also binds the ERGIC tether p115. SNX5, and the functionally redundant SNX6, are required for CHC22 localization independently of their participation in the endosomal ESCPE-1 complex. In tandem, an isoform-specific patch in the CHC22 N-terminal domain separately mediates binding to p115. This dual mode of clathrin recruitment, involving interactions at both N- and C-termini of the heavy chain, is required for CHC22 targeting to ERGIC membranes to mediate the Golgi-bypass route for GLUT4 trafficking. Interference with either interaction inhibits GLUT4 targeting to the GSC, defining a bipartite mechanism regulating a key pathway in human glucose metabolism.
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Affiliation(s)
- Joshua Greig
- Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
- Institute of Structural and Molecular Biology, Birkbeck and University College London, London, WC1E 7HX, UK
| | - George T Bates
- Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
- Institute of Structural and Molecular Biology, Birkbeck and University College London, London, WC1E 7HX, UK
| | - Daowen I Yin
- Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
- Institute of Structural and Molecular Biology, Birkbeck and University College London, London, WC1E 7HX, UK
| | - Kit Briant
- Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
- Institute of Structural and Molecular Biology, Birkbeck and University College London, London, WC1E 7HX, UK
| | - Boris Simonetti
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, UK
| | - Peter J Cullen
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, UK
| | - Frances M Brodsky
- Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK.
- Institute of Structural and Molecular Biology, Birkbeck and University College London, London, WC1E 7HX, UK.
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2
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Gopaldass N, Chen KE, Collins B, Mayer A. Assembly and fission of tubular carriers mediating protein sorting in endosomes. Nat Rev Mol Cell Biol 2024; 25:765-783. [PMID: 38886588 DOI: 10.1038/s41580-024-00746-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/03/2024] [Indexed: 06/20/2024]
Abstract
Endosomes are central protein-sorting stations at the crossroads of numerous membrane trafficking pathways in all eukaryotes. They have a key role in protein homeostasis and cellular signalling and are involved in the pathogenesis of numerous diseases. Endosome-associated protein assemblies or coats collect transmembrane cargo proteins and concentrate them into retrieval domains. These domains can extend into tubular carriers, which then pinch off from the endosomal membrane and deliver the cargoes to appropriate subcellular compartments. Here we discuss novel insights into the structure of a number of tubular membrane coats that mediate the recruitment of cargoes into these carriers, focusing on sorting nexin-based coats such as Retromer, Commander and ESCPE-1. We summarize current and emerging views of how selective tubular endosomal carriers form and detach from endosomes by fission, highlighting structural aspects, conceptual challenges and open questions.
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Affiliation(s)
- Navin Gopaldass
- Department of Immunobiology, University of Lausanne, Epalinges, Switzerland.
| | - Kai-En Chen
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
| | - Brett Collins
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
| | - Andreas Mayer
- Department of Immunobiology, University of Lausanne, Epalinges, Switzerland.
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3
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Jongsma MLM, Bakker N, Neefjes J. Choreographing the motor-driven endosomal dance. J Cell Sci 2022; 136:282885. [PMID: 36382597 PMCID: PMC9845747 DOI: 10.1242/jcs.259689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The endosomal system orchestrates the transport of lipids, proteins and nutrients across the entire cell. Along their journey, endosomes mature, change shape via fusion and fission, and communicate with other organelles. This intriguing endosomal choreography, which includes bidirectional and stop-and-go motions, is coordinated by the microtubule-based motor proteins dynein and kinesin. These motors bridge various endosomal subtypes to the microtubule tracks thanks to their cargo-binding domain interacting with endosome-associated proteins, and their motor domain interacting with microtubules and associated proteins. Together, these interactions determine the mobility of different endosomal structures. In this Review, we provide a comprehensive overview of the factors regulating the different interactions to tune the fascinating dance of endosomes along microtubules.
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Affiliation(s)
- Marlieke L. M. Jongsma
- Department of Cell and Chemical Biology, ONCODE institute, Leiden University Medical Center LUMC, 2333 ZC Leiden, The Netherlands
| | - Nina Bakker
- Department of Cell and Chemical Biology, ONCODE institute, Leiden University Medical Center LUMC, 2333 ZC Leiden, The Netherlands
| | - Jacques Neefjes
- Department of Cell and Chemical Biology, ONCODE institute, Leiden University Medical Center LUMC, 2333 ZC Leiden, The Netherlands,Author for correspondence ()
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4
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Roberts JA, Varma VR, An Y, Varma S, Candia J, Fantoni G, Tiwari V, Anerillas C, Williamson A, Saito A, Loeffler T, Schilcher I, Moaddel R, Khadeer M, Lovett J, Tanaka T, Pletnikova O, Troncoso JC, Bennett DA, Albert MS, Yu K, Niu M, Haroutunian V, Zhang B, Peng J, Croteau DL, Resnick SM, Gorospe M, Bohr VA, Ferrucci L, Thambisetty M. A brain proteomic signature of incipient Alzheimer's disease in young APOE ε4 carriers identifies novel drug targets. SCIENCE ADVANCES 2021; 7:eabi8178. [PMID: 34757788 PMCID: PMC8580310 DOI: 10.1126/sciadv.abi8178] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 09/14/2021] [Indexed: 05/13/2023]
Abstract
Aptamer-based proteomics revealed differentially abundant proteins in Alzheimer’s disease (AD) brains in the Baltimore Longitudinal Study of Aging and Religious Orders Study (mean age, 89 ± 9 years). A subset of these proteins was also differentially abundant in the brains of young APOE ε4 carriers relative to noncarriers (mean age, 39 ± 6 years). Several of these proteins represent targets of approved and experimental drugs for other indications and were validated using orthogonal methods in independent human brain tissue samples as well as in transgenic AD models. Using cell culture–based phenotypic assays, we showed that drugs targeting the cytokine transducer STAT3 and the Src family tyrosine kinases, YES1 and FYN, rescued molecular phenotypes relevant to AD pathogenesis. Our findings may accelerate the development of effective interventions targeting the earliest molecular triggers of AD.
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Affiliation(s)
- Jackson A. Roberts
- Clinical and Translational Neuroscience Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
- Columbia University Vagelos College of Physicians and Surgeons, New York, NY 10032
| | - Vijay R. Varma
- Clinical and Translational Neuroscience Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Yang An
- Brain Aging and Behavior Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | | | - Julián Candia
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Longitudinal Studies Section, Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Giovanna Fantoni
- Clinical Research Core, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Vinod Tiwari
- Section on DNA Repair, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Carlos Anerillas
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Andrew Williamson
- Clinical and Translational Neuroscience Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Atsushi Saito
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Tina Loeffler
- QPS Austria GmbH, Parkring 12, 8074 Grambach, Austria
| | | | - Ruin Moaddel
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Mohammed Khadeer
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Jacqueline Lovett
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Toshiko Tanaka
- Longitudinal Studies Section, Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Olga Pletnikova
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Department of Pathology and Anatomical Sciences, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14203, USA
| | - Juan C. Troncoso
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - David A. Bennett
- Rush Alzheimer’s Disease Center, Rush University Medical Center, Chicago, IL 60612, USA
| | - Marilyn S. Albert
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Kaiwen Yu
- Departments of Structural Biology and Developmental Neurobiology, Center for Proteomics and Metabolomics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Mingming Niu
- Departments of Structural Biology and Developmental Neurobiology, Center for Proteomics and Metabolomics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Vahram Haroutunian
- Departments of Psychiatry and Neuroscience, The Alzheimer’s Disease Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- Mental Illness Research, Education and Clinical Center (MIRECC), James J. Peters VA Medical Center, Bronx, NY 10468, USA
| | - Bin Zhang
- Department of Genetics and Genomic Sciences and Department of Pharmacological Sciences, Mount Sinai Center for Transformative Disease Modeling, Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Junmin Peng
- Departments of Structural Biology and Developmental Neurobiology, Center for Proteomics and Metabolomics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Deborah L. Croteau
- Section on DNA Repair, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Susan M. Resnick
- Brain Aging and Behavior Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Myriam Gorospe
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Vilhelm A. Bohr
- Section on DNA Repair, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Luigi Ferrucci
- Longitudinal Studies Section, Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Madhav Thambisetty
- Clinical and Translational Neuroscience Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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5
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Antón Z, Betin VMS, Simonetti B, Traer CJ, Attar N, Cullen PJ, Lane JD. A heterodimeric SNX4--SNX7 SNX-BAR autophagy complex coordinates ATG9A trafficking for efficient autophagosome assembly. J Cell Sci 2020; 133:jcs246306. [PMID: 32513819 PMCID: PMC7375690 DOI: 10.1242/jcs.246306] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 06/02/2020] [Indexed: 11/24/2022] Open
Abstract
The sorting nexins (SNXs) are a family of peripheral membrane proteins that direct protein trafficking decisions within the endocytic network. Emerging evidence in yeast and mammalian cells implicates a subgroup of SNXs in selective and non-selective forms of autophagy. Using siRNA and CRISPR-Cas9, we demonstrate that the SNX-BAR protein SNX4 is needed for efficient LC3 (also known as MAP1LC3) lipidation and autophagosome assembly in mammalian cells. SNX-BARs exist as homo- and hetero-dimers, and we show that SNX4 forms functional heterodimers with either SNX7 or SNX30 that associate with tubulovesicular endocytic membranes. Detailed image-based analysis during the early stages of autophagosome assembly reveals that SNX4-SNX7 is an autophagy-specific SNX-BAR heterodimer, required for efficient recruitment and/or retention of core autophagy regulators at the nascent isolation membrane. SNX4 partially colocalises with juxtanuclear ATG9A-positive membranes, with our data linking the autophagy defect upon SNX4 disruption to the mis-trafficking and/or retention of ATG9A in the Golgi region. Taken together, our findings show that the SNX4-SNX7 heterodimer coordinates ATG9A trafficking within the endocytic network to establish productive autophagosome assembly sites, thus extending knowledge of SNXs as positive regulators of autophagy.
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Affiliation(s)
- Zuriñe Antón
- Cell Biology Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Virginie M S Betin
- Cell Biology Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Boris Simonetti
- Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Colin J Traer
- Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Naomi Attar
- Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Peter J Cullen
- Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Jon D Lane
- Cell Biology Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
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6
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Munthe E, Raiborg C, Stenmark H, Wenzel EM. Clathrin regulates Wnt/β-catenin signaling by affecting Golgi to plasma membrane transport of transmembrane proteins. J Cell Sci 2020; 133:jcs244467. [PMID: 32546530 DOI: 10.1242/jcs.244467] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 06/04/2020] [Indexed: 12/19/2022] Open
Abstract
The canonical Wnt/β-catenin signaling pathway regulates cell proliferation in development and adult tissue homeostasis. Dysregulated signaling contributes to human diseases, in particular cancer. Growing evidence suggests a role for clathrin and/or endocytosis in the regulation of this pathway, but conflicting results exist and demand a deeper mechanistic understanding. We investigated the consequences of clathrin depletion on Wnt/β-catenin signaling in cell lines and found a pronounced reduction in β-catenin protein levels, which affects the amount of nuclear β-catenin and β-catenin target gene expression. Although we found no evidence that clathrin affects β-catenin levels via endocytosis or multivesicular endosome formation, an inhibition of protein transport through the biosynthetic pathway led to reduced levels of a Wnt co-receptor, low-density lipoprotein receptor-related protein 6 (LRP6), and cell adhesion molecules of the cadherin family, thereby affecting steady-state levels of β-catenin. We conclude that clathrin impacts on Wnt/β-catenin signaling by controlling exocytosis of transmembrane proteins, including cadherins and Wnt co-receptors that together control the membrane-bound and soluble pools of β-catenin.
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Affiliation(s)
- Else Munthe
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, N-0379 Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, N-0316 Oslo, Norway
| | - Camilla Raiborg
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, N-0379 Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, N-0316 Oslo, Norway
| | - Harald Stenmark
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, N-0379 Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, N-0316 Oslo, Norway
| | - Eva Maria Wenzel
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, N-0379 Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, N-0316 Oslo, Norway
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7
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Henkel V, Schürmanns L, Brunner M, Hamann A, Osiewacz HD. Role of sorting nexin PaATG24 in autophagy, aging and development of Podospora anserina. Mech Ageing Dev 2020; 186:111211. [PMID: 32007577 DOI: 10.1016/j.mad.2020.111211] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 12/12/2019] [Accepted: 01/27/2020] [Indexed: 12/18/2022]
Abstract
Sorting nexins are a conserved protein family involved in vesicle transport, membrane trafficking and protein sorting. The sorting nexin ATG24/SNX4 has been demonstrated to be involved in different autophagy pathways and in endosomal trafficking. However, its impact on cellular quality control and on aging and development is still elusive. Here we report studies analyzing the function of PaATG24 in the aging model Podospora anserina. Ablation of PaATG24 leads to a reduced growth rate, infertility, and to a pronounced lifespan reduction. These characteristics are accompanied by alterations of the morphology and size distribution of vacuoles and severe impairments in non-selective and selective autophagy of peroxisomes (pexophagy) and mitochondria (mitophagy). While general autophagy and pexophagy are almost completely blocked, a PaATG24-independent form of mitophagy is induced during aging. In the ΔPaAtg24 mutant a strong accumulation of peroxisomes occurs while mitochondrial abundance is only slightly increased. These mitochondria are partially affected in function. Most strikingly, although some PaATG24-independent mitophagy exists, it appears that this is not sufficient to remove dysfunctional mitochondria efficiently enough to prevent premature aging. Overall our data emphasize the key role of mitochondria in aging and of mitophagy in quality control to keep a population of "healthy" mitochondria during aging.
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Affiliation(s)
- Vanessa Henkel
- Goethe-University, Institute for Molecular Biosciences, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
| | - Lea Schürmanns
- Goethe-University, Institute for Molecular Biosciences, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
| | - Miriam Brunner
- Goethe-University, Institute for Molecular Biosciences, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
| | - Andrea Hamann
- Goethe-University, Institute for Molecular Biosciences, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
| | - Heinz D Osiewacz
- Goethe-University, Institute for Molecular Biosciences, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany.
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8
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Xu S, Nigam SM, Brodin L. Overexpression of SNX3 Decreases Amyloid-β Peptide Production by Reducing Internalization of Amyloid Precursor Protein. NEURODEGENER DIS 2018; 18:26-37. [PMID: 29414832 DOI: 10.1159/000486199] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 12/08/2017] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Sorting nexins (SNXs) have diverse functions in protein sorting and membrane trafficking. Recently, single-nucleotide polymorphisms in SNX3 were found to be associated with Alzheimer disease. However, it remains unknown whether SNX3 participates in amyloid (A)β peptide production. OBJECTIVE To examine the role of SNX3 in Aβ production and APP processing. METHODS The effect of increased expression of SNX3 was studied in HEK293T cells. Aβ peptides were measured by immunoassay. Protein-protein association was analyzed by a bimolecular fluorescence complementation (BiFC) assay. APP uptake was measured with an α-bungarotoxin-binding assay, and flow cytometry was used to measure cell surface APP levels. RESULTS We found that overexpression of SNX3 in HEK293T cells decreases the levels of secreted Aβ and soluble N-terminal APP fragments (sAPPβ). The reduction correlated with a decreased association of APP with BACE1, as revealed by BiFC. This effect may, in part, be explained by a reduced internalization of APP; SNX3 overexpression reduced APP internalization as determined by an α-bungarotoxin-binding assay, and caused increased APP levels on the cell surface, as shown by flow cytometry. In addition, SNX3 overexpression increased the cellular levels of full-length APP. CONCLUSION These results provide evidence that SNX3 regulates Aβ production by influencing the internalization of APP.
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Affiliation(s)
- Shaohua Xu
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Saket M Nigam
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Lennart Brodin
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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9
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Aznar N, Sun N, Dunkel Y, Ear J, Buschman MD, Ghosh P. A Daple-Akt feed-forward loop enhances noncanonical Wnt signals by compartmentalizing β-catenin. Mol Biol Cell 2017; 28:3709-3723. [PMID: 29021338 PMCID: PMC5706997 DOI: 10.1091/mbc.e17-06-0405] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 08/04/2017] [Accepted: 10/06/2017] [Indexed: 01/12/2023] Open
Abstract
Balance between canonical and noncanonical Wnt pathways controls the β-catenin transcriptional program; how the noncanonical pathway antagonizes the canonical pathway remains unclear. We show that Daple, an enhancer of noncanonical Wnt signals, accomplishes that goal by dictating the subcellular distribution of β-catenin in cells. Cellular proliferation is antagonistically regulated by canonical and noncanonical Wnt signals; their dysbalance triggers cancers. We previously showed that a multimodular signal transducer, Daple, enhances PI3-K→Akt signals within the noncanonical Wnt signaling pathway and antagonistically inhibits canonical Wnt responses. Here we demonstrate that the PI3-K→Akt pathway serves as a positive feedback loop that further enhances noncanonical Wnt signals by compartmentalizing β-catenin. By phosphorylating the phosphoinositide- (PI) binding domain of Daple, Akt abolishes Daple’s ability to bind PI3-P-enriched endosomes that engage dynein motor complex for long-distance trafficking of β-catenin/E-cadherin complexes to pericentriolar recycling endosomes (PCREs). Phosphorylation compartmentalizes Daple/β-catenin/E-cadherin complexes to cell–cell contact sites, enhances noncanonical Wnt signals, and thereby suppresses colony growth. Dephosphorylation compartmentalizes β-catenin on PCREs, a specialized compartment for prolonged unopposed canonical Wnt signaling, and enhances colony growth. Cancer-associated Daple mutants that are insensitive to Akt mimic a constitutively dephosphorylated state. This work not only identifies Daple as a platform for cross-talk between Akt and the noncanonical Wnt pathway but also reveals the impact of such cross-talk on tumor cell phenotypes that are critical for cancer initiation and progression.
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Affiliation(s)
- Nicolas Aznar
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Nina Sun
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Ying Dunkel
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Jason Ear
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Matthew D Buschman
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Pradipta Ghosh
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093 .,Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093.,Moores Cancer Centre, University of California, San Diego, La Jolla, CA 92093
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10
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Abubakar YS, Zheng W, Olsson S, Zhou J. Updated Insight into the Physiological and Pathological Roles of the Retromer Complex. Int J Mol Sci 2017; 18:ijms18081601. [PMID: 28757549 PMCID: PMC5577995 DOI: 10.3390/ijms18081601] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 07/20/2017] [Accepted: 07/21/2017] [Indexed: 12/13/2022] Open
Abstract
Retromer complexes mediate protein trafficking from the endosomes to the trans-Golgi network (TGN) or through direct recycling to the plasma membrane. In yeast, they consist of a conserved trimer of the cargo selective complex (CSC), Vps26-Vps35-Vps29 and a dimer of sorting nexins (SNXs), Vps5-Vps17. In mammals, the CSC interacts with different kinds of SNX proteins in addition to the mammalian homologues of Vps5 and Vps17, which further diversifies retromer functions. The retromer complex plays important roles in many cellular processes including restriction of invading pathogens. In this review, we summarize some recent developments in our understanding of the physiological and pathological functions of the retromer complex.
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Affiliation(s)
- Yakubu Saddeeq Abubakar
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Wenhui Zheng
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Stefan Olsson
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Jie Zhou
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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11
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Quantitative Co-Localization and Pattern Analysis of Endo-Lysosomal Cargo in Subcellular Image Cytometry and Validation on Synthetic Image Sets. Methods Mol Biol 2017; 1594:93-128. [PMID: 28456978 DOI: 10.1007/978-1-4939-6934-0_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Late endosomes and lysosomes (LE/LYSs) play a central role in trafficking of endocytic cargo, secretion of exosomes, and hydrolysis of ingested proteins and lipids. Failure in such processes can lead to lysosomal storage disorders in which a particular metabolite accumulates within LE/LYSs. Analysis of endocytic trafficking relies heavily on quantitative fluorescence microscopy, but evaluation of the huge image data sets is challenging and demands computer-assisted statistical tools. Here, we describe how to use SpatTrack ( www.sdu.dk/bmb/spattrack ), an imaging toolbox, which we developed for quantification of the distribution and dynamics of endo-lysosomal cargo from fluorescence images of living cells. First, we explain how to analyze experimental images of endocytic processes in Niemann Pick C2 disease fibroblasts using SpatTrack. We demonstrate how to quantify the location of the sterol-binding protein NPC2 in LE/LYSs relative to cholesterol -rich lysosomal storage organelles (LSOs) stained with filipin. Second, we show how to simulate realistic vesicle patterns in the cell geometry using Markov Chain Monte Carlo and suitable inter-vesicle and cell-vesicle interaction potentials. Finally, we use such synthetic vesicle patterns as "ground truth" for validation of two-channel analysis tools in SpatTrack, revealing their high reliability. An improved version of SpatTrack for microscopy-based quantification of cargo transport through the endo-lysosomal system accompanies this protocol.
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Hierro A, Gershlick DC, Rojas AL, Bonifacino JS. Formation of Tubulovesicular Carriers from Endosomes and Their Fusion to the trans-Golgi Network. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 318:159-202. [PMID: 26315886 DOI: 10.1016/bs.ircmb.2015.05.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Endosomes undergo extensive spatiotemporal rearrangements as proteins and lipids flux through them in a series of fusion and fission events. These controlled changes enable the concentration of cargo for eventual degradation while ensuring the proper recycling of other components. A growing body of studies has now defined multiple recycling pathways from endosomes to the trans-Golgi network (TGN) which differ in their molecular machineries. The recycling process requires specific sets of lipids, coats, adaptors, and accessory proteins that coordinate cargo selection with membrane deformation and its association with the cytoskeleton. Specific tethering factors and SNARE (SNAP (Soluble NSF Attachment Protein) Receptor) complexes are then required for the docking and fusion with the acceptor membrane. Herein, we summarize some of the current knowledge of the machineries that govern the retrograde transport from endosomes to the TGN.
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Affiliation(s)
- Aitor Hierro
- Structural Biology Unit, CIC bioGUNE, Derio, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - David C Gershlick
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | | | - 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, USA
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Chi RJ, Harrison MS, Burd CG. Biogenesis of endosome-derived transport carriers. Cell Mol Life Sci 2015; 72:3441-3455. [PMID: 26022064 DOI: 10.1007/s00018-015-1935-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 05/18/2015] [Accepted: 05/21/2015] [Indexed: 01/29/2023]
Abstract
Sorting of macromolecules within the endosomal system is vital for physiological control of nutrient homeostasis, cell motility, and proteostasis. Trafficking routes that export macromolecules from the endosome via vesicle and tubule transport carriers constitute plasma membrane recycling and retrograde endosome-to-Golgi pathways. Proteins of the sorting nexin family have been discovered to function at nearly every step of endosomal transport carrier biogenesis and it is becoming increasingly clear that they form the core machineries of cargo-specific transport pathways that are closely integrated with cellular physiology. Here, we summarize recent progress in elucidating the pathways that mediate the biogenesis of endosome-derived transport carriers.
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Affiliation(s)
- Richard J Chi
- Department of Cell Biology, Yale School of Medicine, SHM C425B, 333 Cedar Street, New Haven, CT 06520, USA
| | - Megan S Harrison
- Department of Cell Biology, Yale School of Medicine, SHM C425B, 333 Cedar Street, New Haven, CT 06520, USA
| | - Christopher G Burd
- Department of Cell Biology, Yale School of Medicine, SHM C425B, 333 Cedar Street, New Haven, CT 06520, USA
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Kornilova ES. Receptor-mediated endocytosis and cytoskeleton. BIOCHEMISTRY (MOSCOW) 2014; 79:865-78. [DOI: 10.1134/s0006297914090041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Sakane H, Horii Y, Nogami S, Kawano Y, Kaneko-Kawano T, Shirataki H. α-Taxilin interacts with sorting nexin 4 and participates in the recycling pathway of transferrin receptor. PLoS One 2014; 9:e93509. [PMID: 24690921 PMCID: PMC3972091 DOI: 10.1371/journal.pone.0093509] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 03/06/2014] [Indexed: 01/09/2023] Open
Abstract
Membrane traffic plays a crucial role in delivering proteins and lipids to their intracellular destinations. We previously identified α-taxilin as a binding partner of the syntaxin family, which is involved in intracellular vesicle traffic. α-Taxilin is overexpressed in tumor tissues and interacts with polymerized tubulin, but the precise function of α-taxilin remains unclear. Receptor proteins on the plasma membrane are internalized, delivered to early endosomes and then either sorted to the lysosome for degradation or recycled back to the plasma membrane. In this study, we found that knockdown of α-taxilin induced the lysosomal degradation of transferrin receptor (TfnR), a well-known receptor which is generally recycled back to the plasma membrane after internalization, and impeded the recycling of transferrin. α-Taxilin was immunoprecipitated with sorting nexin 4 (SNX4), which is involved in the recycling of TfnR. Furthermore, knockdown of α-taxilin decreased the number and length of SNX4-positive tubular structures. We report for the first time that α-taxilin interacts with SNX4 and plays a role in the recycling pathway of TfnR.
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Affiliation(s)
- Hiroshi Sakane
- Department of Molecular and Cell Biology, Graduate school of Medicine, Dokkyo Medical University, Mibu, Tochigi, Japan
| | - Yukimi Horii
- Department of Molecular and Cell Biology, Graduate school of Medicine, Dokkyo Medical University, Mibu, Tochigi, Japan
| | - Satoru Nogami
- Department of Molecular and Cell Biology, Graduate school of Medicine, Dokkyo Medical University, Mibu, Tochigi, Japan
| | - Yoji Kawano
- Department of Molecular and Cell Biology, Graduate school of Medicine, Dokkyo Medical University, Mibu, Tochigi, Japan
| | - Takako Kaneko-Kawano
- Department of Molecular and Cell Biology, Graduate school of Medicine, Dokkyo Medical University, Mibu, Tochigi, Japan
| | - Hiromichi Shirataki
- Department of Molecular and Cell Biology, Graduate school of Medicine, Dokkyo Medical University, Mibu, Tochigi, Japan
- * E-mail:
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Cellular Mechanisms in Nanomaterial Internalization, Intracellular Trafficking, and Toxicity. Nanotoxicology 2014. [DOI: 10.1007/978-1-4614-8993-1_9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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17
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Danson C, Brown E, Hemmings OJ, McGough IJ, Yarwood S, Heesom KJ, Carlton JG, Martin-Serrano J, May MT, Verkade P, Cullen PJ. SNX15 links clathrin endocytosis to the PtdIns3P early endosome independently of the APPL1 endosome. J Cell Sci 2013; 126:4885-99. [PMID: 23986476 DOI: 10.1242/jcs.125732] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Sorting nexins (SNXs) are key regulators of the endosomal network. In designing an RNAi-mediated loss-of-function screen, we establish that of 30 human SNXs only SNX3, SNX5, SNX9, SNX15 and SNX21 appear to regulate EGF receptor degradative sorting. Suppression of SNX15 results in a delay in receptor degradation arising from a defect in movement of newly internalised EGF-receptor-labelled vesicles into early endosomes. Besides a phosphatidylinositol 3-phosphate- and PX-domain-dependent association to early endosomes, SNX15 also associates with clathrin-coated pits and clathrin-coated vesicles by direct binding to clathrin through a non-canonical clathrin-binding box. From live-cell imaging, it was identified that the activated EGF receptor enters distinct sub-populations of SNX15- and APPL1-labelled peripheral endocytic vesicles, which do not undergo heterotypic fusion. The SNX15-decorated receptor-containing sub-population does, however, undergo direct fusion with the Rab5-labelled early endosome. Our data are consistent with a model in which the EGF receptor enters the early endosome following clathrin-mediated endocytosis through at least two parallel pathways: maturation through an APPL1-intermediate compartment and an alternative more direct fusion between SNX15-decorated endocytic vesicles and the Rab5-positive early endosome.
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Affiliation(s)
- Chris Danson
- The Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
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Hunt SD, Townley AK, Danson CM, Cullen PJ, Stephens DJ. Microtubule motors mediate endosomal sorting by maintaining functional domain organization. J Cell Sci 2013; 126:2493-501. [PMID: 23549789 PMCID: PMC3679488 DOI: 10.1242/jcs.122317] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Many microtubule motors have been shown to couple to endosomal membranes. These motors include dynein in addition to many different kinesin family members. Sorting nexins (SNXs) are central to the organization and function of endosomes. These proteins can actively shape endosomal membranes and couple directly or indirectly to the minus-end microtubule motor dynein. Motor proteins acting on endosomes drive their motility, dictate their morphology and affect cargo segregation. We have used well-characterized members of the SNX family to elucidate motor coupling using high-resolution light microscopy coupled with depletion of specific microtubule motors. Endosomal domains labelled with SNX1, SNX4 and SNX8 couple to discrete combinations of dynein and kinesin motors. These specific combinations govern the structure and motility of each SNX-coated membrane in addition to the segregation of distinct functional endosomal subdomains. Taken together, our data show that these key features of endosome dynamics are governed by the same set of opposing microtubule motors. Thus, microtubule motors help to define the mosaic layout of endosomes that underpins cargo sorting.
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Affiliation(s)
- Sylvie D Hunt
- Cell Biology Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
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Abstract
The retromer complex is a vital element of the endosomal protein sorting machinery that is conserved across all eukaryotes. Retromer is most closely associated with the endosome-to-Golgi retrieval pathway and is necessary to maintain an active pool of hydrolase receptors in the trans-Golgi network. Recent progress in studies of retromer have identified new retromer-interacting proteins, including the WASH complex and cargo such as the Wntless/MIG-14 protein, which now extends the role of retromer beyond the endosome-to-Golgi pathway and has revealed that retromer is required for aspects of endosome-to-plasma membrane sorting and regulation of signalling events. The interactions between the retromer complex and other macromolecular protein complexes now show how endosomal protein sorting is coordinated with actin assembly and movement along microtubules, and place retromer squarely at the centre of a complex set of protein machinery that governs endosomal protein sorting. Dysregulation of retromer-mediated endosomal protein sorting leads to various pathologies, including neurodegenerative diseases such as Alzheimer disease and spastic paraplegia and the mechanisms underlying these pathologies are starting to be understood. In this Commentary, I will highlight recent advances in the understanding of retromer-mediated endosomal protein sorting and discuss how retromer contributes to a diverse set of physiological processes.
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McGough IJ, Cullen PJ. Clathrin is not required for SNX-BAR-retromer-mediated carrier formation. J Cell Sci 2012; 126:45-52. [PMID: 23015596 DOI: 10.1242/jcs.112904] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Clathrin has been implicated in retromer-mediated trafficking, but its precise function remains elusive. Given the importance of retromers for efficient endosomal sorting, we have sought to clarify the relationship between clathrin and the SNX-BAR retromer. We find that the retromer SNX-BARs do not interact directly or indirectly with clathrin. In addition, we observe that SNX-BAR-retromer tubules and carriers are not clathrin coated. Furthermore, perturbing clathrin function, by overexpressing a dominant-negative clathrin or through suppression of clathrin expression, has no detectable effect on the frequency of SNX-BAR-retromer tubulation. We propose that SNX-BAR-retromer-mediated membrane deformation and carrier formation does not require clathrin, and hence the role of clathrin in SNX-BAR-retromer function would appear to lie in pre-SNX-BAR-retromer cargo sorting.
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Affiliation(s)
- Ian J McGough
- Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK
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21
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Iversen TG, Frerker N, Sandvig K. Uptake of ricinB-quantum dot nanoparticles by a macropinocytosis-like mechanism. J Nanobiotechnology 2012; 10:33. [PMID: 22849338 PMCID: PMC3466139 DOI: 10.1186/1477-3155-10-33] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 07/23/2012] [Indexed: 12/23/2022] Open
Abstract
Background There is a huge effort in developing ligand-mediated targeting of nanoparticles to diseased cells and tissue. The plant toxin ricin has been shown to enter cells by utilizing both dynamin-dependent and -independent endocytic pathways. Thus, it is a representative ligand for addressing the important issue of whether even a relatively small ligand-nanoparticle conjugate can gain access to the same endocytic pathways as the free ligand. Results Here we present a systematic study concerning the internalization mechanism of ricinB:Quantum dot (QD) nanoparticle conjugates in HeLa cells. Contrary to uptake of ricin itself, we found that internalization of ricinB:QDs was inhibited in HeLa cells expressing dominant-negative dynamin. Both clathrin-, Rho-dependent uptake as well as a specific form of macropinocytosis involve dynamin. However, the ricinB:QD uptake was not affected by siRNA-mediated knockdown of clathrin or inhibition of Rho-dependent uptake caused by treating cells with the Clostridium C3 transferase. RicinB:QD uptake was significantly reduced by cholesterol depletion with methyl-β-cyclodextrin and by inhibitors of actin polymerization such as cytochalasin D. Finally, we found that uptake of ricinB:QDs was blocked by the amiloride analog EIPA, an inhibitor of macropinocytosis. Upon entry, the ricinB:QDs co-localized with dextran, a marker for fluid-phase uptake. Thus, internalization of ricinB:QDs in HeLa cells critically relies on a dynamin-dependent macropinocytosis-like mechanism. Conclusions Our results demonstrate that internalization of a ligand-nanoparticle conjugate can be dependent on other endocytic mechanisms than those used by the free ligand, highlighting the challenges of using ligand-mediated targeting of nanoparticles-based drug delivery vehicles to cells of diseased tissues.
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Affiliation(s)
- Tore Geir Iversen
- Centre for Cancer Biomedicine, Faculty Division Norwegian Radium Hospital, University of Oslo, Oslo, Norway.
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Annexin A1 and A2: roles in retrograde trafficking of Shiga toxin. PLoS One 2012; 7:e40429. [PMID: 22792315 PMCID: PMC3391278 DOI: 10.1371/journal.pone.0040429] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 06/06/2012] [Indexed: 01/05/2023] Open
Abstract
Annexins constitute a family of calcium and membrane binding proteins. As annexin A1 and A2 have previously been linked to various membrane trafficking events, we initiated this study to investigate the role of these annexins in the uptake and intracellular transport of the bacterial Shiga toxin (Stx) and the plant toxin ricin. Once endocytosed, both toxins are retrogradely transported from endosomes to the Golgi apparatus and the endoplasmic reticulum before being targeted to the cytosol where they inhibit protein synthesis. This study was performed to obtain new information both about toxin transport and the function of annexin A1 and annexin A2. Our data show that depletion of annexin A1 or A2 alters the retrograde transport of Stx but not ricin, without affecting toxin binding or internalization. Knockdown of annexin A1 increases Golgi transport of Stx, whereas knockdown of annexin A2 slightly decreases the same transport step. Interestingly, annexin A1 was found in proximity to cytoplasmic phospholipase A2 (cPLA2), and the basal as well as the increased Golgi transport of Stx upon annexin A1 knockdown is dependent on cPLA2 activity. In conclusion, annexin A1 and A2 have different roles in Stx transport to the trans-Golgi network. The most prominent role is played by annexin A1 which normally works as a negative regulator of retrograde transport from the endosomes to the Golgi network, most likely by complex formation and inhibition of cPLA2.
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Abstract
The endo-lysosomal system is an interconnected tubulo-vesicular network that acts as a sorting station to process and distribute internalised cargo. This network accepts cargoes from both the plasma membrane and the biosynthetic pathway, and directs these cargos either towards the lysosome for degradation, the peri-nuclear recycling endosome for return to the cell surface, or to the trans-Golgi network. These intracellular membranes are variously enriched in different phosphoinositides that help to shape compartmental identity. These lipids act to localise a number of phosphoinositide-binding proteins that function as sorting machineries to regulate endosomal cargo sorting. Herein we discuss regulation of these machineries by phosphoinositides and explore how phosphoinositide-switching contributes toward sorting decisions made at this platform.
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Affiliation(s)
- Peter J Cullen
- Henry Wellcome Integrated Signaling Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, BS8 1TD, Bristol, United Kingdom,
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Cullen PJ, Korswagen HC. Sorting nexins provide diversity for retromer-dependent trafficking events. Nat Cell Biol 2011; 14:29-37. [PMID: 22193161 PMCID: PMC3613977 DOI: 10.1038/ncb2374] [Citation(s) in RCA: 265] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Sorting nexins are a large family of evolutionarily conserved phosphoinositide-binding proteins that have fundamental roles in orchestrating cargo sorting through the membranous maze that is the endosomal network. One ancient group of complexes that contain sorting nexins is the retromer. Here we discuss how retromer complexes regulate endosomal sorting, and describe how this is generating exciting new insight into the central role played by endosomal sorting in development and homeostasis of normal tissues.
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Affiliation(s)
- Peter J. Cullen
- Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, U.K
| | - Hendrik C. Korswagen
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
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Insights into the PX (phox-homology) domain and SNX (sorting nexin) protein families: structures, functions and roles in disease. Biochem J 2011; 441:39-59. [DOI: 10.1042/bj20111226] [Citation(s) in RCA: 212] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The mammalian genome encodes 49 proteins that possess a PX (phox-homology) domain, responsible for membrane attachment to organelles of the secretory and endocytic system via binding of phosphoinositide lipids. The PX domain proteins, most of which are classified as SNXs (sorting nexins), constitute an extremely diverse family of molecules that play varied roles in membrane trafficking, cell signalling, membrane remodelling and organelle motility. In the present review, we present an overview of the family, incorporating recent functional and structural insights, and propose an updated classification of the proteins into distinct subfamilies on the basis of these insights. Almost all PX domain proteins bind PtdIns3P and are recruited to early endosomal membranes. Although other specificities and localizations have been reported for a select few family members, the molecular basis for binding to other lipids is still not clear. The PX domain is also emerging as an important protein–protein interaction domain, binding endocytic and exocytic machinery, transmembrane proteins and many other molecules. A comprehensive survey of the molecular interactions governed by PX proteins highlights the functional diversity of the family as trafficking cargo adaptors and membrane-associated scaffolds regulating cell signalling. Finally, we examine the mounting evidence linking PX proteins to different disorders, in particular focusing on their emerging importance in both pathogen invasion and amyloid production in Alzheimer's disease.
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Abstract
From the pioneering work of Mabel and Lowell Hokin in the 1950s, the biology of this specific isomer of hexahydroxycyclohexane and its phosphorylated derivatives, in the form of inositol phosphates and phosphoinositides, has expanded to fill virtually every corner of cell biology, whole-organism physiology and development. In the present paper, I give a personal view of the role played by phosphoinositides in regulating the function of the endosomal network, and, in so doing, highlight some of the basic properties through which phosphoinositides regulate cell function.
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Abstract
Microtubule motor proteins play key roles in the spatial organization of intracellular organelles as well as the transfer of material between them. This is well illustrated both by the vectorial transfer of biosynthetic cargo from the endoplasmic reticulum to the Golgi apparatus as well as the sorting of secretory and endocytic cargo in the endosomal system. Roles have been described for dynein and kinesin motors in each of these steps. Cytoplasmic dynein is a highly complex motor comprising multiple subunits that provide functional specialization. The family of human kinesins includes over 40 members. This complexity provides immense functional diversity, yet little is known of the specific requirements and functions of individual motors during discrete membrane trafficking steps. In the present paper, we describe some of the latest findings in this area that seek to define the mechanisms of recruitment and control of activity of microtubule motors in spatial organization and cargo trafficking through the endosomal network.
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Abstract
The retromer complex coordinates retrograde transport of cargo proteins between endosomes and the trans-Golgi network. The sorting nexin SNX3 is required for the retrograde trafficking of Wntless, but not of other retrograde cargo proteins, revealing that the cargo specificity of retromer is provided by the sorting nexins.
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Harterink M, Port F, Lorenowicz MJ, McGough IJ, Silhankova M, Betist MC, van Weering JRT, van Heesbeen RGHP, Middelkoop TC, Basler K, Cullen PJ, Korswagen HC. A SNX3-dependent retromer pathway mediates retrograde transport of the Wnt sorting receptor Wntless and is required for Wnt secretion. Nat Cell Biol 2011; 13:914-923. [PMID: 21725319 PMCID: PMC4052212 DOI: 10.1038/ncb2281] [Citation(s) in RCA: 259] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 05/17/2011] [Indexed: 02/08/2023]
Abstract
Wnt proteins are lipid-modified glycoproteins that play a central role in development, adult tissue homeostasis and disease. Secretion of Wnt proteins is mediated by the Wnt-binding protein Wntless (Wls), which transports Wnt from the Golgi network to the cell surface for release. It has recently been shown that recycling of Wls through a retromer-dependent endosome-to-Golgi trafficking pathway is required for efficient Wnt secretion, but the mechanism of this retrograde transport pathway is poorly understood. Here, we report that Wls recycling is mediated through a retromer pathway that is independent of the retromer sorting nexins SNX1-SNX2 and SNX5-SNX6. We have found that the unrelated sorting nexin, SNX3, has an evolutionarily conserved function in Wls recycling and Wnt secretion and show that SNX3 interacts directly with the cargo-selective subcomplex of the retromer to sort Wls into a morphologically distinct retrieval pathway. These results demonstrate that SNX3 is part of an alternative retromer pathway that functionally separates the retrograde transport of Wls from other retromer cargo.
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Affiliation(s)
- Martin Harterink
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Fillip Port
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Magdalena J. Lorenowicz
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Ian J. McGough
- Henry Wellcome Integrated Signaling Laboratories, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Marie Silhankova
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Marco C. Betist
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Jan R. T. van Weering
- Henry Wellcome Integrated Signaling Laboratories, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Roy G. H. P. van Heesbeen
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Teije C. Middelkoop
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Konrad Basler
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Peter J. Cullen
- Henry Wellcome Integrated Signaling Laboratories, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Hendrik C. Korswagen
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
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Abstract
The endosomal network is an organized array of intracellular, membranous compartments that function as sorting sites for endosomal and biosynthetic cargo. The fate of endocytic cargo is reliant upon interactions with a number of molecularly distinct sorting complexes, which tightly control the relationship between sorting of their respective cargo and the physical process of membrane re-scuplturing required for the formation of transport carries. One such complex, retromer, mediates retrograde transport from endosomes to the trans-Golgi network (TGN). Disregulation of retromer has been implicated in a host of disease states including late-onset Alzheimer's. Rather than give a broad overview of retromer biology, here we aim to outline the recent advances in understanding this complex, focussing on the involvement of both clathrin and the cytoskeleton in retromer function.
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Affiliation(s)
- Ian J McGough
- Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK
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31
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Abstract
Some proteins and lipids traffic from the plasma membrane to the trans Golgi network (TGN)/Golgi apparatus and the endoplasmic reticulum, via the retrograde transport route. Endosomes are an obligatory through station. Whether early, recycling and late endosomes all hand off material to the TGN have remained a matter of debate. In this review, we give a short historical overview on how retrograde transport was discovered and explored. We then summarize and critically discuss data that have been put forward in favour of the existence of trafficking interfaces between each of the different endocytic localizations and the TGN. We finally point out some conceptual and technological challenges that will have to be met to establish definite conclusions for each of these scenarios.
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Affiliation(s)
- Ludger Johannes
- Traffic, Signaling, and Delivery Laboratory, Centre de Recherche, Institut Curie, CNRS UMR144, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
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Pust S, Barth H, Sandvig K. Clostridium botulinum C2 toxin is internalized by clathrin- and Rho-dependent mechanisms. Cell Microbiol 2011; 12:1809-20. [PMID: 20690924 DOI: 10.1111/j.1462-5822.2010.01512.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Clostridium botulinum C2 toxin is an ADP-ribosyltransferase, causing depolymerization of the actin cytoskeleton in eukaryotic cells. The C2 toxin is a binary toxin consisting of the enzymatic subunit C2I and the binding subunit C2II. Proteolytical activation of the binding subunit triggers the formation of heptameric structures (C2IIa), which bind to cellular receptors. C2I is able to bind to C2IIa oligomers, and it has been suggested that the whole complex is internalized by a raft-dependent mechanism. Here we analysed by which mechanism C2 toxin is endocytosed. In HeLa cells expressing a dominant-negative dynamin mutant, cytotoxicity and C2 toxin uptake were blocked. Furthermore, siRNA-mediated knockdown of flotillins or inhibition of Arf6 function, proteins suggested to be involved in dynamin-independent endocytosis, did not affect C2 toxicity. Knockdown of caveolin did not inhibit endocytosis of C2 toxin, whereas inhibition of clathrin function reduced the uptake of C2 toxin and delayed the cytotoxic effect. Finally, we found evidence for a Rho-mediated uptake of C2 toxin. In conclusion, C2 toxin is endocytosed by dynamin-dependent mechanisms and we provide evidence for involvement of clathrin and Rho.
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Affiliation(s)
- Sascha Pust
- Centre for Cancer Biomedicine and Institute for Cancer Research, Department of Biochemistry, Oslo University Hospital and University of Oslo, 0316 Oslo, Norway
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Anitei M, Wassmer T, Stange C, Hoflack B. Bidirectional transport between the trans-Golgi network and the endosomal system. Mol Membr Biol 2010; 27:443-56. [DOI: 10.3109/09687688.2010.522601] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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van Weering JRT, Verkade P, Cullen PJ. SNX-BAR proteins in phosphoinositide-mediated, tubular-based endosomal sorting. Semin Cell Dev Biol 2009; 21:371-80. [PMID: 19914387 DOI: 10.1016/j.semcdb.2009.11.009] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Accepted: 11/06/2009] [Indexed: 12/11/2022]
Abstract
The endocytic network is morphologically characterized by a wide variety of membrane bound compartments that are able to undergo dynamic re-modeling through tubular and vesicular structures. The precise molecular mechanisms governing such re-modeling, and the events that co-ordinated this with the major role of endosomes, cargo sorting, remain unclear. That said, recent work on a protein family of sorting nexins (SNX) - especially a subfamily of SNX that contain a BAR domain (SNX-BARs) - has begun to shed some much needed light on these issues and in particular the process of tubular-based endosomal sorting. SNX-BARs are evolutionary conserved in endosomal protein complexes such as retromer, where they co-ordinate membrane deformation with cargo selection. Furthermore a central theme emerges of SNX-BARs linking the forming membrane carrier to cytoskeletal elements for transport through motor proteins such as dynein. By studying these SNX-BARs, we are gaining an increasingly detailed appreciation of the mechanistic basis of endosomal sorting and how this highly dynamic process functions in health and disease.
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Affiliation(s)
- Jan R T van Weering
- The Henry Wellcome Integrated Signalling Laboratories, Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
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Regulation of endosomal clathrin and retromer-mediated endosome to Golgi retrograde transport by the J-domain protein RME-8. EMBO J 2009; 28:3290-302. [PMID: 19763082 DOI: 10.1038/emboj.2009.272] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Accepted: 07/28/2009] [Indexed: 12/11/2022] Open
Abstract
After endocytosis, most cargo enters the pleiomorphic early endosomes in which sorting occurs. As endosomes mature, transmembrane cargo can be sequestered into inwardly budding vesicles for degradation, or can exit the endosome in membrane tubules for recycling to the plasma membrane, the recycling endosome, or the Golgi apparatus. Endosome to Golgi transport requires the retromer complex. Without retromer, recycling cargo such as the MIG-14/Wntless protein aberrantly enters the degradative pathway and is depleted from the Golgi. Endosome-associated clathrin also affects the recycling of retrograde cargo and has been shown to function in the formation of endosomal subdomains. Here, we find that the Caemorhabditis elegans endosomal J-domain protein RME-8 associates with the retromer component SNX-1. Loss of SNX-1, RME-8, or the clathrin chaperone Hsc70/HSP-1 leads to over-accumulation of endosomal clathrin, reduced clathrin dynamics, and missorting of MIG-14 to the lysosome. Our results indicate a mechanism, whereby retromer can regulate endosomal clathrin dynamics through RME-8 and Hsc70, promoting the sorting of recycling cargo into the retrograde pathway.
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