1
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Zhang D. Interplay between endoplasmic reticulum membrane contacts and actomyosin cytoskeleton. Cytoskeleton (Hoboken) 2020; 77:241-248. [PMID: 32543125 DOI: 10.1002/cm.21623] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/11/2020] [Accepted: 06/11/2020] [Indexed: 12/13/2022]
Abstract
Eukaryotic membrane-bound organelles, exhibiting distinctive morphologies, dynamics and functions, are interconnected at membrane contact sites (MCSs) through numerous tethering machineries. MCSs are required for many fundamental cellular processes, such as non-vesicular lipid transfer, calcium transport and organelle homeostasis. Actin cytoskeleton and myosin motors are known to dynamically interact with different membrane boundaries, facilitating organelle movements and partitioning. Intriguingly, recent studies have pinpointed a special participation of actomyosin at various MCSs involving the endoplasmic reticulum (ER), the most extensive membranous organelle in the cell. Here, I summarize emerging roles of ER MCSs in modulating actomyosin structures and discuss feedback functions of such actomyosin regulation at these MCSs.
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Affiliation(s)
- Dan Zhang
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore
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2
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Bosmani C, Leuba F, Hanna N, Bach F, Burdet F, Pagni M, Hagedorn M, Soldati T. Vacuolins and myosin VII are required for phagocytic uptake and phagosomal membrane recycling in Dictyostelium discoideum. J Cell Sci 2020; 133:jcs242974. [PMID: 32482795 DOI: 10.1242/jcs.242974] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 05/18/2020] [Indexed: 12/17/2022] Open
Abstract
Flotillins are lipid raft residents involved in membrane trafficking and recycling of plasma membrane proteins. Dictyostelium discoideum uses phagocytosis to kill, digest and feed on bacteria. It possesses three flotillin-like vacuolins that are strongly associated with membranes and that gradually accumulate on maturing phagosomes. Absence of vacuolins reduced adhesion and particle recognition resulting in a drastic reduction in the uptake of various types of particles. This was caused by a block in the recycling of plasma membrane components and the absence of their specific cortex-associated proteins. In addition, absence of vacuolins also impaired phagolysosome biogenesis, without significantly impacting killing and digestion of a range of bacteria. Strikingly, both absence and overexpression of vacuolins induced a strong downregulation of myosin VII (also known as MyoI) expression, as well as its binding partner talin A. Episomal expression of myosin VII fully rescued defects in uptake and adhesion but not in phagosome maturation. These results suggest a dual role for vacuolins: a novel mechanism involving membrane microdomains and myosin VII-talin A in clustering phagosomal receptors and adhesion molecules at the plasma membrane, and a role in phagolysosomal biogenesis.
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Affiliation(s)
- Cristina Bosmani
- Départment de Biochimie, Faculté des Sciences, Université de Genève, CH-1205 Geneva, Switzerland
| | - Florence Leuba
- Départment de Biochimie, Faculté des Sciences, Université de Genève, CH-1205 Geneva, Switzerland
| | - Nabil Hanna
- Départment de Biochimie, Faculté des Sciences, Université de Genève, CH-1205 Geneva, Switzerland
| | - Frauke Bach
- Section Parasitology, Bernhard Nocht Institute for Tropical Medicine, D-20359 Hamburg, Germany
| | - Frédéric Burdet
- Vital-IT, Swiss Institute of Bioinformatics, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Marco Pagni
- Vital-IT, Swiss Institute of Bioinformatics, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Monica Hagedorn
- Section Parasitology, Bernhard Nocht Institute for Tropical Medicine, D-20359 Hamburg, Germany
| | - Thierry Soldati
- Départment de Biochimie, Faculté des Sciences, Université de Genève, CH-1205 Geneva, Switzerland
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3
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Brzeska H, Gonzalez J, Korn ED, Titus MA. Basic-hydrophobic sites are localized in conserved positions inside and outside of PH domains and affect localization of Dictyostelium myosin 1s. Mol Biol Cell 2020; 31:101-117. [PMID: 31774725 PMCID: PMC6960411 DOI: 10.1091/mbc.e19-08-0475] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/14/2019] [Accepted: 11/22/2019] [Indexed: 11/21/2022] Open
Abstract
Myosin 1s have critical roles in linking membranes to the actin cytoskeleton via direct binding to acidic lipids. Lipid binding may occur through PIP3/PIP2-specific PH domains or nonspecific ionic interactions involving basic-hydrophobic (BH) sites but the mechanism of myosin 1s distinctive lipid targeting is poorly understood. Now we show that PH domains occur in all Dictyostelium myosin 1s and that the BH sites of Myo1A, B, C, D, and F are in conserved positions near the β3/β4 loops of their PH domains. In spite of these shared lipid-binding sites, we observe significant differences in myosin 1s highly dynamic localizations. All myosin 1s except Myo1A are present in macropinocytic structures but only Myo1B and Myo1C are enriched at the edges of macropinocytic cups and associate with the actin in actin waves. In contrast, Myo1D, E, and F are enclosed by the actin wave. Mutations of BH sites affect localization of all Dictyostelium myosin 1s. Notably, mutation of the BH site located within the PH domains of PIP3-specific Myo1D and Myo1F completely eradicates membrane binding. Thus, BH sites are important determinants of motor targeting and may have a similar role in the localization of other myosin 1s.
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Affiliation(s)
- Hanna Brzeska
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Jesus Gonzalez
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Edward D. Korn
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Margaret A. Titus
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455
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4
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Sharma D, Otto G, Warren EC, Beesley P, King JS, Williams RSB. Gamma secretase orthologs are required for lysosomal activity and autophagic degradation in Dictyostelium discoideum, independent of PSEN (presenilin) proteolytic function. Autophagy 2019; 15:1407-1418. [PMID: 30806144 PMCID: PMC6613883 DOI: 10.1080/15548627.2019.1586245] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mutations in the γ-secretase complex are strongly associated with familial Alzheimer disease. Both proteolytic and non-proteolytic functions for the γ-secretase complex have been previously described in mammalian model organisms, but their relative contributions to disease pathology remain unclear. Here, we dissect the roles of orthologs of the γ-secretase components in the model system Dictyostelium, focusing on endocytosis, lysosomal activity and autophagy. In this model, we show that the orthologs of PSEN (psenA and psenB), Ncstn (nicastrin) and Aph-1 (gamma-secretase subunit Aph-1), are necessary for optimal fluid-phase uptake by macropinocytosis and in multicellular development under basic pH conditions. Disruption of either psenA/B or Aph-1 proteins also leads to disrupted phagosomal proteolysis as well as decreased autophagosomal acidification and autophagic flux. This indicates a general defect in lysosomal trafficking and degradation, which we show leads to the accumulation of ubiquitinated protein aggregates in cells lacking psenA/B and Aph-1 proteins. Importantly, we find that all the endocytic defects observed in Dictyostelium PSEN ortholog mutants can be fully rescued by proteolytically inactive Dictyostelium psenB and human PSEN1 proteins. Our data therefore demonstrates an evolutionarily conserved non-proteolytic role for presenilin, and γ-secretase component orthologs, in maintaining Dictyostelium lysosomal trafficking and autophagy. Abbreviations: Atg8: autophagy protein 8a; Aph-1: gamma-secretase subunit Aph-1; crtA: calreticulin; ER: endoplasmic reticulum; GFP: green fluorescent protein; GSK3B: glycogen synthase kinase 3 beta; Ncstn: nicastrin; PSEN1: presenilin 1; psenA and psenB: Dictyostelium presenilin A and B; TRITC; tetramethylrhodamine isothiocyanate.
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Affiliation(s)
- Devdutt Sharma
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
| | - Grant Otto
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
| | - Eleanor C Warren
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
| | - Philip Beesley
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
| | - Jason S King
- b Department of Biomedical Sciences , University of Sheffield , Sheffield , UK
| | - Robin S B Williams
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
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5
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Sakai R, Fukuda R, Unida S, Aki M, Ono Y, Endo A, Kusumi S, Koga D, Fukushima T, Komada M, Okiyoneda T. The integral function of the endocytic recycling compartment is regulated by RFFL-mediated ubiquitylation of Rab11 effectors. J Cell Sci 2019; 132:jcs.228007. [PMID: 30659120 DOI: 10.1242/jcs.228007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 01/03/2019] [Indexed: 12/11/2022] Open
Abstract
Endocytic trafficking is regulated by ubiquitylation (also known as ubiquitination) of cargoes and endocytic machineries. The role of ubiquitylation in lysosomal delivery has been well documented, but its role in the recycling pathway is largely unknown. Here, we report that the ubiquitin (Ub) ligase RFFL regulates ubiquitylation of endocytic recycling regulators. An RFFL dominant-negative (DN) mutant induced clustering of endocytic recycling compartments (ERCs) and delayed endocytic cargo recycling without affecting lysosomal traffic. A BioID RFFL interactome analysis revealed that RFFL interacts with the Rab11 effectors EHD1, MICALL1 and class I Rab11-FIPs. The RFFL DN mutant strongly captured these Rab11 effectors and inhibited their ubiquitylation. The prolonged interaction of RFFL with Rab11 effectors was sufficient to induce the clustered ERC phenotype and to delay cargo recycling. RFFL directly ubiquitylates these Rab11 effectors in vitro, but RFFL knockout (KO) only reduced the ubiquitylation of Rab11-FIP1. RFFL KO had a minimal effect on the ubiquitylation of EHD1, MICALL1, and Rab11-FIP2, and failed to delay transferrin recycling. These results suggest that multiple Ub ligases including RFFL regulate the ubiquitylation of Rab11 effectors, determining the integral function of the ERC.
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Affiliation(s)
- Ryohei Sakai
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Hyogo 669-1337, Japan
| | - Ryosuke Fukuda
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Hyogo 669-1337, Japan
| | - Shin Unida
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Hyogo 669-1337, Japan
| | - Misaki Aki
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Hyogo 669-1337, Japan
| | - Yuji Ono
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Hyogo 669-1337, Japan
| | - Akinori Endo
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Satoshi Kusumi
- Division of Morphological Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan
| | - Daisuke Koga
- Department of Microscopic Anatomy and Cell Biology, Asahikawa Medical University, Asahikawa 078-8510, Hokkaido, Japan
| | - Toshiaki Fukushima
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Masayuki Komada
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Tsukasa Okiyoneda
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Hyogo 669-1337, Japan
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6
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Maringer K, Yarbrough A, Sims-Lucas S, Saheb E, Jawed S, Bush J. Dictyostelium discoideum RabS and Rab2 colocalize with the Golgi and contractile vacuole system and regulate osmoregulation. J Biosci 2017; 41:205-17. [PMID: 27240981 DOI: 10.1007/s12038-016-9610-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Small-molecular-weight GTPase Rab2 has been shown to be a resident of pre-Golgi intermediates and is required for protein transport from the ER to the Golgi complex; however, Rab2 has yet to be characterized in Dictyostelium discoideum. DdRabS is a Dictyostelium Rab that is 80 percent homologous to DdRab1 which is required for protein transport between the ER and Golgi. Expression of GFP-tagged DdRab2 and DdRabS proteins showed localization to Golgi membranes and to the contractile vacuole system (CV) in Dictyostelium. Microscopic imaging indicates that the DdRab2 and DdRabS proteins localize at, and are essential for, the proper structure of Golgi membranes and the CV system. Dominant negative (DN) forms show fractionation of Golgi membranes, supporting their role in the structure and function of it. DdRab2 and DdRabS proteins, and their dominant negative and constitutively active (CA) forms, affect osmoregulation of the cells, possibly by the influx and discharge of fluids, which suggests a role in the function of the CV system. This is the first evidence of GTPases being localized to both Golgi membranes and the CV system in Dictyostelium.
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Affiliation(s)
- Katherine Maringer
- Division of Nephrology, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15201, USA
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7
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Buckley CM, Gopaldass N, Bosmani C, Johnston SA, Soldati T, Insall RH, King JS. WASH drives early recycling from macropinosomes and phagosomes to maintain surface phagocytic receptors. Proc Natl Acad Sci U S A 2016; 113:E5906-E5915. [PMID: 27647881 PMCID: PMC5056073 DOI: 10.1073/pnas.1524532113] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Macropinocytosis is an ancient mechanism that allows cells to harvest nutrients from extracellular media, which also allows immune cells to sample antigens from their surroundings. During macropinosome formation, bulk plasma membrane is internalized with all its integral proteins. It is vital for cells to salvage these proteins before degradation, but the mechanisms for sorting them are not known. Here we describe the evolutionarily conserved recruitment of the WASH (WASP and SCAR homolog) complex to both macropinosomes and phagosomes within a minute of internalization. Using Dictyostelium, we demonstrate that WASH drives protein sorting and recycling from macropinosomes and is thus essential to maintain surface receptor levels and sustain phagocytosis. WASH functionally interacts with the retromer complex at both early and late phases of macropinosome maturation, but mediates recycling via retromer-dependent and -independent pathways. WASH mutants consequently have decreased membrane levels of integrins and other surface proteins. This study reveals an important pathway enabling cells to sustain macropinocytosis without bulk degradation of plasma membrane components.
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Affiliation(s)
- Catherine M Buckley
- Department of Biomedical Sciences, Centre for Membrane Interactions and Dynamics, University of Sheffield, Sheffield S10 2TN, United Kingdom; Bateson Centre, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Navin Gopaldass
- Department of Biochemistry, University of Geneva, CH-1211 Geneva, Switzerland
| | - Cristina Bosmani
- Department of Biochemistry, University of Geneva, CH-1211 Geneva, Switzerland
| | - Simon A Johnston
- Bateson Centre, University of Sheffield, Sheffield S10 2TN, United Kingdom; Department of Infection, Immunity and Cardiovascular Sciences, University of Sheffield Medical School, Sheffield S10 2RX, United Kingdom
| | - Thierry Soldati
- Department of Biochemistry, University of Geneva, CH-1211 Geneva, Switzerland
| | - Robert H Insall
- Beatson Institute for Cancer Research, Glasgow G61 1BD, United Kingdom
| | - Jason S King
- Department of Biomedical Sciences, Centre for Membrane Interactions and Dynamics, University of Sheffield, Sheffield S10 2TN, United Kingdom; Bateson Centre, University of Sheffield, Sheffield S10 2TN, United Kingdom;
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8
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Brzeska H, Koech H, Pridham KJ, Korn ED, Titus MA. Selective localization of myosin-I proteins in macropinosomes and actin waves. Cytoskeleton (Hoboken) 2016; 73:68-82. [PMID: 26801966 DOI: 10.1002/cm.21275] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 01/20/2016] [Accepted: 01/20/2016] [Indexed: 01/19/2023]
Abstract
Class I myosins are widely expressed with roles in endocytosis and cell migration in a variety of cell types. Dictyostelium express multiple myosin Is, including three short-tailed (Myo1A, Myo1E, Myo1F) and three long-tailed (Myo1B, Myo1C, Myo1D). Here we report the molecular basis of the specific localizations of short-tailed Myo1A, Myo1E, and Myo1F compared to our previously determined localization of long-tailed Myo1B. Myo1A and Myo1B have common and unique localizations consistent with the various features of their tail region; specifically the BH sites in their tails are required for their association with the plasma membrane and heads are sufficient for relocalization to the front of polarized cells. Myo1A does not localize to actin waves and macropinocytic protrusions, in agreement with the absence of a tail region which is required for these localizations of Myo1B. However, in spite of the overall similarity of their domain structures, the cellular distributions of Myo1E and Myo1F are quite different from Myo1A. Myo1E and Myo1F, but not Myo1A, are associated with macropinocytic cups and actin waves. The localizations of Myo1E and Myo1F in macropinocytic structures and actin waves differ from the localization of Myo1B. Myo1B colocalizes with F-actin in the actin waves and at the tips of mature macropinocytic cups whereas Myo1E and Myo1F are in the interior of actin waves and along the entire surface of macropinocytic cups. Our results point to different mechanisms of targeting of short- and long-tailed myosin Is, and are consistent with these myosins having both shared and divergent cellular functions.
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Affiliation(s)
- Hanna Brzeska
- Laboratory of Cell Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Hilary Koech
- Laboratory of Cell Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Kevin J Pridham
- Laboratory of Cell Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Edward D Korn
- Laboratory of Cell Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Margaret A Titus
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota
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9
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Zhang C, Chen Y, Yin Y, Ji HH, Shim WB, Hou Y, Zhou M, Li XD, Ma Z. A small molecule species specifically inhibits Fusarium myosin I. Environ Microbiol 2015; 17:2735-46. [PMID: 25404531 DOI: 10.1111/1462-2920.12711] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/03/2014] [Accepted: 11/05/2014] [Indexed: 11/28/2022]
Abstract
Fusarium head blight (FHB) caused by Fusarium graminearum is a devastating disease of cereal crops worldwide. Recently, a novel fungicide JS399-19 has been launched into the marketplace to manage FHB. It is compelling that JS399-19 shows highly inhibitory activity towards some Fusarium species, but not to other fungi, indicating that it is an environmentally compatible fungicide. To explore the mode of action of this species-specific compound, we conducted a whole-genome transcript profiling together with genetic and biochemical assays, and discovered that JS399-19 targets the myosin I of F. graminearum (FgMyo1). FgMyo1 is essential for F. graminearum growth. A point mutation S217L or E420K in FgMyo1 is responsible for F. graminearum resistance to JS399-19. In addition, transformation of F. graminearum with the myosin I gene of Magnaporthe grisea, the causal agent of rice blast, also led to JS399-19 resistance. JS399-19 strongly inhibits the ATPase activity of the wild-type FgMyo1, but not the mutated FgMyo1(S217L/E420K) . These results provide us a new insight into the design of species-specific antifungal compounds. Furthermore, our strategy can be applied to identify novel drug targets in various pathogenic organisms.
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Affiliation(s)
- Chengqi Zhang
- Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Yun Chen
- Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Yanni Yin
- Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Huan-Hong Ji
- National Laboratory of Integrated Management of Insect Pests and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Won-Bo Shim
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, 77843-2132, USA
| | - Yiping Hou
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
| | - Mingguo Zhou
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
| | - Xiang-Dong Li
- National Laboratory of Integrated Management of Insect Pests and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Zhonghua Ma
- Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
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10
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Liburd J, Chitayat S, Crawley SW, Munro K, Miller E, Denis CM, Spencer HL, Côté GP, Smith SP. Structure of the small Dictyostelium discoideum myosin light chain MlcB provides insights into MyoB IQ motif recognition. J Biol Chem 2014; 289:17030-42. [PMID: 24790102 DOI: 10.1074/jbc.m113.536532] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Dictyostelium discoideum MyoB is a class I myosin involved in the formation and retraction of membrane projections, cortical tension generation, membrane recycling, and phagosome maturation. The MyoB-specific, single-lobe EF-hand light chain MlcB binds the sole IQ motif of MyoB with submicromolar affinity in the absence and presence of Ca(2+). However, the structural features of this novel myosin light chain and its interaction with its cognate IQ motif remain uncharacterized. Here, we describe the NMR-derived solution structure of apoMlcB, which displays a globular four-helix bundle. Helix 1 adopts a unique orientation when compared with the apo states of the EF-hand calcium-binding proteins calmodulin, S100B, and calbindin D9k. NMR-based chemical shift perturbation mapping identified a hydrophobic MyoB IQ binding surface that involves amino acid residues in helices I and IV and the functional N-terminal Ca(2+) binding loop, a site that appears to be maintained when MlcB adopts the holo state. Complementary mutagenesis and binding studies indicated that residues Ile-701, Phe-705, and Trp-708 of the MyoB IQ motif are critical for recognition of MlcB, which together allowed the generation of a structural model of the apoMlcB-MyoB IQ complex. We conclude that the mode of IQ motif recognition by the novel single-lobe MlcB differs considerably from that of stereotypical bilobal light chains such as calmodulin.
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Affiliation(s)
- Janine Liburd
- From the Department of Biomedical and Molecular Sciences and
| | - Seth Chitayat
- From the Department of Biomedical and Molecular Sciences and
| | - Scott W Crawley
- From the Department of Biomedical and Molecular Sciences and
| | - Kim Munro
- the Protein Function Discovery Group, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Emily Miller
- From the Department of Biomedical and Molecular Sciences and
| | - Chris M Denis
- From the Department of Biomedical and Molecular Sciences and
| | - Holly L Spencer
- From the Department of Biomedical and Molecular Sciences and
| | - Graham P Côté
- From the Department of Biomedical and Molecular Sciences and the Protein Function Discovery Group, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Steven P Smith
- From the Department of Biomedical and Molecular Sciences and the Protein Function Discovery Group, Queen's University, Kingston, Ontario K7L 3N6, Canada
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11
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Zhang X, Soldati T. Detecting, visualizing and quantitating the generation of reactive oxygen species in an amoeba model system. J Vis Exp 2013:e50717. [PMID: 24300479 PMCID: PMC3970549 DOI: 10.3791/50717] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Reactive oxygen species (ROS) comprise a range of reactive and short-lived, oxygen-containing molecules, which are dynamically interconverted or eliminated either catalytically or spontaneously. Due to the short life spans of most ROS and the diversity of their sources and subcellular localizations, a complete picture can be obtained only by careful measurements using a combination of protocols. Here, we present a set of three different protocols using OxyBurst Green (OBG)-coated beads, or dihydroethidium (DHE) and Amplex UltraRed (AUR), to monitor qualitatively and quantitatively various ROS in professional phagocytes such as Dictyostelium. We optimised the beads coating procedures and used OBG-coated beads and live microscopy to dynamically visualize intraphagosomal ROS generation at the single cell level. We identified lipopolysaccharide (LPS) from E. coli as a potent stimulator for ROS generation in Dictyostelium. In addition, we developed real time, medium-throughput assays using DHE and AUR to quantitatively measure intracellular superoxide and extracellular H2O2 production, respectively.
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Affiliation(s)
- Xuezhi Zhang
- Department of Biochemistry, University of Geneva
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12
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Tiwari A, Jung JJ, Inamdar SM, Nihalani D, Choudhury A. The myosin motor Myo1c is required for VEGFR2 delivery to the cell surface and for angiogenic signaling. Am J Physiol Heart Circ Physiol 2012; 304:H687-96. [PMID: 23262137 DOI: 10.1152/ajpheart.00744.2012] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Vascular endothelial growth factor receptor-2 (VEGFR2) is a receptor tyrosine kinase that is expressed in endothelial cells and regulates angiogenic signal transduction under both physiological and pathological conditions. VEGFR2 turnover at the plasma membrane (PM) is regulated by its transport through endocytic and secretory transport pathways. Short-range cargo trafficking along actin filaments is commonly regulated by motor proteins of myosin superfamily. In the current study, performed in primary human endothelial cells, we demonstrate that unconventional myosin 1c (Myo1c; class I family member) regulates the localization of VEGFR2 at the PM. We further demonstrate that the recruitment of VEGFR2 to the PM and its colocalization with Myo1c and caveolin-1 occur in response to VEGF-A (VEGF) stimulation. In addition, VEGF-induced delivery of VEGFR2 to the cell surface requires Myo1c; surface VEGFR2 levels are reduced in the absence of Myo1c and, more importantly, are restored by the overexpression of wild-type but not mutant Myo1c. Subcellular density gradient fractionation revealed that partitioning of VEGFR2 into caveolin-1- and Myo1c-enriched membrane fractions is dependent on VEGF stimulation. Myo1c depletion resulted in increased VEGF-induced VEGFR2 transport to the lysosomes for degradation and was rescued by applying either brefeldin A, which blocks trafficking between the endoplasmic reticulum and the Golgi complex, or dynasore, an inhibitor of dynamin-mediated endocytosis. Myo1c depletion also reduced VEGF-induced VEGFR2 phosphorylation at Y1175 and phosphorylation-dependent activation of ERK1/2 and c-Src kinase, leading to reduced cell proliferation and cell migration. This is the first report demonstrating that Myo1c is an important mediator of VEGF-induced VEGFR2 delivery to the cell surface and plays a role in angiogenic signaling.
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Affiliation(s)
- Ajit Tiwari
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA 52242, USA
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13
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Dieckmann R, Guého A, Monroy R, Ruppert T, Bloomfield G, Soldati T. The balance in the delivery of ER components and the vacuolar proton pump to the phagosome depends on myosin IK in Dictyostelium. Mol Cell Proteomics 2012; 11:886-900. [PMID: 22736568 DOI: 10.1074/mcp.m112.017608] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In Dictyostelium, the cytoskeletal proteins Actin binding protein 1 (Abp1) and the class I myosin MyoK directly interact and couple actin dynamics to membrane deformation during phagocytosis. Together with the kinase PakB, they build a regulatory switch that controls the efficiency of uptake of large particles. As a basis for further functional dissection, exhaustive phagosome proteomics was performed and established that about 1300 proteins participate in phagosome biogenesis. Then, quantitative and comparative proteomic analysis of phagosome maturation was performed to investigate the impact of the absence of MyoK or Abp1. Immunoblots and two-dimensional differential gel electrophoresis of phagosomes isolated from myoK-null and abp1-null cells were used to determine the relative abundance of proteins during the course of maturation. Immunoblot profiling showed that absence of Abp1 alters the maturation profile of its direct binding partners such as actin and the Arp2/3 complex, suggesting that Abp1 directly regulates actin dynamics at the phagosome. Comparative two-dimensional differential gel electrophoresis analysis resulted in the quantification of mutant-to-wild type abundance ratios at all stages of maturation for over one hundred identified proteins. Coordinated temporal changes in these ratio profiles determined the classification of identified proteins into functional groups. Ratio profiling revealed that the early delivery of ER proteins to the phagosome was affected by the absence of MyoK and was coupled to a reciprocal imbalance in the delivery of the vacuolar proton pump and Rab11 GTPases. As direct functional consequences, a delayed acidification and a reduced intraphagosomal proteolysis were demonstrated in vivo in myoK-null cells. In conclusion, the absence of MyoK alters the balance of the contributions of the ER and an endo-lysosomal compartment, and slows down phagosome acidification as well as the speed and efficiency of particle degradation inside the phagosome.
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Affiliation(s)
- Régis Dieckmann
- Départment de Biochimie, University de Genève, Sciences II, 30 quay Ernest Ansermet, CH-1211 Genève-4, Switzerland
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14
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Brzeska H, Guag J, Preston GM, Titus MA, Korn ED. Molecular basis of dynamic relocalization of Dictyostelium myosin IB. J Biol Chem 2012; 287:14923-36. [PMID: 22367211 DOI: 10.1074/jbc.m111.318667] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Class I myosins have a single heavy chain comprising an N-terminal motor domain with actin-activated ATPase activity and a C-terminal globular tail with a basic region that binds to acidic phospholipids. These myosins contribute to the formation of actin-rich protrusions such as pseudopodia, but regulation of the dynamic localization to these structures is not understood. Previously, we found that Acanthamoeba myosin IC binds to acidic phospholipids in vitro through a short sequence of basic and hydrophobic amino acids, BH site, based on the charge density of the phospholipids. The tail of Dictyostelium myosin IB (DMIB) also contains a BH site. We now report that the BH site is essential for DMIB binding to the plasma membrane and describe the molecular basis of the dynamic relocalization of DMIB in live cells. Endogenous DMIB is localized uniformly on the plasma membrane of resting cells, at active protrusions and cell-cell contacts of randomly moving cells, and at the front of motile polarized cells. The BH site is required for association of DMIB with the plasma membrane at all stages where it colocalizes with phosphoinositide bisphosphate/phosphoinositide trisphosphate (PIP(2)/PIP(3)). The charge-based specificity of the BH site allows for in vivo specificity of DMIB for PIP(2)/PIP(3) similar to the PH domain-based specificity of other class I myosins. However, DMIB-head is required for relocalization of DMIB to the front of migrating cells. Motor activity is not essential, but the actin binding site in the head is important. Thus, dynamic relocalization of DMIB is determined principally by the local PIP(2)/PIP(3) concentration in the plasma membrane and cytoplasmic F-actin.
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Affiliation(s)
- Hanna Brzeska
- Laboratory of Cell Biology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA.
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15
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Gopaldass N, Patel D, Kratzke R, Dieckmann R, Hausherr S, Hagedorn M, Monroy R, Krüger J, Neuhaus EM, Hoffmann E, Hille K, Kuznetsov SA, Soldati T. Dynamin A, Myosin IB and Abp1 couple phagosome maturation to F-actin binding. Traffic 2011; 13:120-30. [PMID: 22008230 DOI: 10.1111/j.1600-0854.2011.01296.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The role of actin, class I myosins and dynamin in endocytic uptake processes is well characterized, but their role during endo-phagosomal membrane trafficking and maturation is less clear. In Dictyostelium, knockout of myosin IB (myoB) leads to a defect in membrane protein recycling from endosomes back to the plasma membrane. Here, we show that actin plays a central role in the morphology and function of the endocytic pathway. Indeed, latrunculin B (LatB) induces endosome tubulation, a phenotype also observed in dynamin A (dymA)-null cells. Knockout of dymA impairs phagosome acidification, whereas knockout of myoB delays reneutralization, a phenotype mimicked by a low dose of LatB. As a read out for actin-dependent processes during maturation, we monitored the capacity of purified phagosomes to bind F-actin in vitro, and correlated this with the presence of actin-binding and membrane-trafficking proteins. Phagosomes isolated from myoB-null cells showed an increased binding to F-actin, especially late phagosomes. In contrast, early phagosomes from dymA-null cells showed reduced binding to F-actin while late phagosomes were unaffected. We provide evidence that Abp1 is the main F-actin-binding protein in this assay and is central for the interplay between DymA and MyoB during phagosome maturation.
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Affiliation(s)
- Navin Gopaldass
- Départment de Biochimie, Faculté des Sciences, Université de Genève, Sciences II, 30 quai Ernest Ansermet, Geneva, Switzerland
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16
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Crawley SW, Liburd J, Shaw K, Jung Y, Smith SP, Côté GP. Identification of calmodulin and MlcC as light chains for Dictyostelium myosin-I isozymes. Biochemistry 2011; 50:6579-88. [PMID: 21671662 DOI: 10.1021/bi2007178] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Dictyostelium discoideum express seven single-headed myosin-I isozymes (MyoA-MyoE and MyoK) that drive motile processes at the cell membrane. The light chains for MyoA and MyoE were identified by expressing Flag-tagged constructs consisting of the motor domain and the two IQ motifs in the neck region in Dictyostelium. The MyoA and MyoE constructs both copurified with calmodulin. Isothermal titration calorimetry (ITC) showed that apo-calmodulin bound to peptides corresponding to the MyoA and MyoE IQ motifs with micromolar affinity. In the presence of calcium, calmodulin cross-linked two IQ motif peptides, with one domain binding with nanomolar affinity and the other with micromolar affinity. The IQ motifs were required for the actin-activated MgATPase activity of MyoA but not MyoE; however, neither myosin exhibited calcium-dependent activity. A Flag-tagged construct consisting of the MyoC motor domain and the three IQ motifs in the adjacent neck region bound a novel 8.6 kDa two EF-hand protein named MlcC, for myosin light chain for MyoC. MlcC is most similar to the C-terminal domain of calmodulin but does not bind calcium. ITC studies showed that MlcC binds IQ1 and IQ2 but not IQ3 of MyoC. IQ3 contains a proline residue that may render it nonfunctional. Each long-tailed Dictyostelium myosin-I has now been shown to have a unique light chain (MyoB-MlcB, MyoC-MlcC, and MyoD-MlcD), whereas the short-tailed myosins-I, MyoA and MyoE, have the multifunctional calmodulin as a light chain. The diversity in light chain composition is likely to contribute to the distinct cellular functions of each myosin-I isozyme.
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Affiliation(s)
- Scott W Crawley
- Department of Biochemistry, Queen's University, Kingston, Ontario, Canada K7L 3N6
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17
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Rump A, Scholz T, Thiel C, Hartmann FK, Uta P, Hinrichs MH, Taft MH, Tsiavaliaris G. Myosin-1C associates with microtubules and stabilizes the mitotic spindle during cell division. J Cell Sci 2011; 124:2521-8. [PMID: 21712373 DOI: 10.1242/jcs.084335] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The mitotic spindle in eukaryotic cells is composed of a bipolar array of microtubules (MTs) and associated proteins that are required during mitosis for the correct partitioning of the two sets of chromosomes to the daughter cells. In addition to the well-established functions of MT-associated proteins (MAPs) and MT-based motors in cell division, there is increasing evidence that the F-actin-based myosin motors are important mediators of F-actin-MT interactions during mitosis. Here, we report the functional characterization of the long-tailed class-1 myosin myosin-1C from Dictyostelium discoideum during mitosis. Our data reveal that myosin-1C binds to MTs and has a role in maintenance of spindle stability for accurate chromosome separation. Both myosin-1C motor function and tail-domain-mediated MT-F-actin interactions are required for the cell-cycle-dependent relocalization of the protein from the cell periphery to the spindle. We show that the association of myosin-1C with MTs is mediated through the tail domain. The myosin-1C tail can inhibit kinesin motor activity, increase the stability of MTs, and form crosslinks between MTs and F-actin. These data illustrate that myosin-1C is involved in the regulation of MT function during mitosis in D. discoideum.
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Affiliation(s)
- Agrani Rump
- Laboratory for Cellular Biophysics, Institute for Biophysical Chemistry, Hannover Medical School, 30625 Hannover, Germany
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18
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Heisler FF, Loebrich S, Pechmann Y, Maier N, Zivkovic AR, Tokito M, Hausrat TJ, Schweizer M, Bähring R, Holzbaur ELF, Schmitz D, Kneussel M. Muskelin regulates actin filament- and microtubule-based GABA(A) receptor transport in neurons. Neuron 2011; 70:66-81. [PMID: 21482357 DOI: 10.1016/j.neuron.2011.03.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/26/2011] [Indexed: 12/29/2022]
Abstract
Intracellular transport regulates protein turnover including endocytosis. Because of the spatial segregation of F-actin and microtubules, internalized cargo vesicles need to employ myosin and dynein motors to traverse both cytoskeletal compartments. Factors specifying cargo delivery across both tracks remain unknown. We identified muskelin to interconnect retrograde F-actin- and microtubule-dependent GABA(A) receptor (GABA(A)R) trafficking. GABA(A)Rs regulate synaptic transmission, plasticity, and network oscillations. GABA(A)R α1 and muskelin interact directly, undergo neuronal cotransport, and associate with myosin VI or dynein motor complexes in subsequent steps of GABA(A)R endocytosis. Inhibition of either transport route selectively interferes with receptor internalization or degradation. Newly generated muskelin KO mice display depletion of both transport steps and a high-frequency ripple oscillation phenotype. A diluted coat color of muskelin KOs further suggests muskelin transport functions beyond neurons. Our data suggest the concept that specific trafficking factors help cargoes to traverse both F-actin and microtubule compartments, thereby regulating their fate.
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Affiliation(s)
- Frank F Heisler
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH, University of Hamburg Medical School, Falkenried 94, D-20251 Hamburg, Germany
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19
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Spitznagel D, O'Rourke JF, Leddy N, Hanrahan O, Nolan DP. Identification and characterization of an unusual class I myosin involved in vesicle traffic in Trypanosoma brucei. PLoS One 2010; 5:e12282. [PMID: 20808867 PMCID: PMC2924389 DOI: 10.1371/journal.pone.0012282] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Accepted: 07/16/2010] [Indexed: 01/19/2023] Open
Abstract
Myosins are a multimember family of motor proteins with diverse functions in eukaryotic cells. African trypanosomes possess only two candidate myosins and thus represent a useful system for functional analysis of these motors. One of these candidates is an unusual class I myosin (TbMyo1) that is expressed at similar levels but organized differently during the life cycle of Trypanosoma brucei. This myosin localizes to the polarized endocytic pathway in bloodstream forms of the parasite. This organization is actin dependent. Knock down of TbMyo1 results in a significant reduction in endocytic activity, a cessation in cell division and eventually cell death. A striking morphological feature in these cells is an enlargement of the flagellar pocket, which is consistent with an imbalance in traffic to and from the surface. In contrast TbMyo1 is distributed throughout procyclic forms of the tsetse vector and a loss of ∼90% of the protein has no obvious effects on growth or morphology. These results reveal a life cycle stage specific requirement for this myosin in essential endocytic traffic and represent the first description of the involvement of a motor protein in vesicle traffic in these parasites.
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Affiliation(s)
- Diana Spitznagel
- Molecular Parasitology Group, School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
| | - John F. O'Rourke
- European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, United Kingdom
| | - Neal Leddy
- Centre for Microscopy and Analysis, Trinity College Dublin, Dublin, Ireland
| | - Orla Hanrahan
- Molecular Parasitology Group, School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
| | - Derek P. Nolan
- Molecular Parasitology Group, School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
- * E-mail:
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20
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Calmodulin dissociation regulates Myo5 recruitment and function at endocytic sites. EMBO J 2010; 29:2899-914. [PMID: 20647997 DOI: 10.1038/emboj.2010.159] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 06/21/2010] [Indexed: 11/09/2022] Open
Abstract
Myosins-I are conserved proteins that bear an N-terminal motor head followed by a Tail Homology 1 (TH1) lipid-binding domain. Some myosins-I have an additional C-terminal extension (C(ext)) that promotes Arp2/3 complex-dependent actin polymerization. The head and the tail are separated by a neck that binds calmodulin or calmodulin-related light chains. Myosins-I are known to participate in actin-dependent membrane remodelling. However, the molecular mechanisms controlling their recruitment and their biochemical activities in vivo are far from being understood. In this study, we provided evidence suggesting the existence of an inhibitory interaction between the TH1 domain of the yeast myosin-I Myo5 and its C(ext). The TH1 domain prevented binding of the Myo5 C(ext) to the yeast WIP homologue Vrp1, Myo5 C(ext)-induced actin polymerization and recruitment of the Myo5 C(ext) to endocytic sites. Our data also indicated that calmodulin dissociation from Myo5 weakened the interaction between the neck and TH1 domains and the C(ext). Concomitantly, calmodulin dissociation triggered Myo5 binding to Vrp1, extended the myosin-I lifespan at endocytic sites and activated Myo5-induced actin polymerization.
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21
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McConnell RE, Tyska MJ. Leveraging the membrane - cytoskeleton interface with myosin-1. Trends Cell Biol 2010; 20:418-26. [PMID: 20471271 DOI: 10.1016/j.tcb.2010.04.004] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 04/15/2010] [Accepted: 04/16/2010] [Indexed: 12/19/2022]
Abstract
Class 1 myosins are small motor proteins with the ability to simultaneously bind to actin filaments and cellular membranes. Given their ability to generate mechanical force, and their high prevalence in many cell types, these molecules are well positioned to carry out several important biological functions at the interface of membrane and the actin cytoskeleton. Indeed, recent studies implicate these motors in endocytosis, exocytosis, release of extracellular vesicles, and the regulation of tension between membrane and the cytoskeleton. Many class 1 myosins also exhibit a load-dependent mechano-chemical cycle that enables them to maintain tension for long periods of time without hydrolyzing ATP. These properties put myosins-1 in a unique position to regulate dynamic membrane-cytoskeleton interactions and respond to physical forces during these events.
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Affiliation(s)
- Russell E McConnell
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37205, USA
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22
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Chen S, Song Y, Cao J, Wang G, Wei H, Xu X, Lu L. Localization and function of calmodulin in live-cells of Aspergillus nidulans. Fungal Genet Biol 2010; 47:268-78. [DOI: 10.1016/j.fgb.2009.12.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Revised: 10/29/2009] [Accepted: 12/17/2009] [Indexed: 10/20/2022]
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23
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Abstract
All cell functions that involve membrane deformation or a change in cell shape (e.g., endocytosis, exocytosis, cell motility, and cytokinesis) are regulated by membrane tension. While molecular contacts between the plasma membrane and the underlying actin cytoskeleton are known to make significant contributions to membrane tension, little is known about the molecules that mediate these interactions. We used an optical trap to directly probe the molecular determinants of membrane tension in isolated organelles and in living cells. Here, we show that class I myosins, a family of membrane-binding, actin-based motor proteins, mediate membrane/cytoskeleton adhesion and thus, make major contributions to membrane tension. These studies show that class I myosins directly control the mechanical properties of the cell membrane; they also position these motor proteins as master regulators of cellular events involving membrane deformation.
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Johnson JR, Jiang H, Smith BD. Zinc(II)-Coordinated Oligotyrosine: A New Class of Cell Penetrating Peptide. Bioconjug Chem 2008; 19:1033-9. [DOI: 10.1021/bc700466z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- James R. Johnson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556 USA
| | - Hua Jiang
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556 USA
| | - Bradley D. Smith
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556 USA
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25
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Endocytosis and the Actin Cytoskeleton in Dictyostelium discoideum. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 267:343-97. [DOI: 10.1016/s1937-6448(08)00633-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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26
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Dieckmann R, Gopaldass N, Escalera C, Soldati T. Monitoring time-dependent maturation changes in purified phagosomes from Dictyostelium discoideum. Methods Mol Biol 2008; 445:327-337. [PMID: 18425460 DOI: 10.1007/978-1-59745-157-4_21] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The amoeba Dictyostelium discoideum is an established model to study phagocytosis. The sequence of events leading to the internalization and degradation of a particle is conserved in D. discoideum compared to metazoan cells. As its small haploid genome has been sequenced, it is now amenable to genome-wide analysis including organelle proteomics. Therefore, we adapted to Dictyostelium the classical protocol to purify phagosomes formed by ingestion of latex beads particles. The pulse-chase protocol detailed here gives easy access to pure, intact, and synchronized phagosomes from representative stages of the entire process of phagosome maturation. Recently, this protocol was used to generate individual temporal profiles of proteins and lipids during phagosome maturation generating a proteomic fingerprint of six maturation stages (1). In addition, immunolabeling of phagosomes on a coverslip was developed to visualize and quantitate antigen distribution at the level of individual phagosomes.
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Affiliation(s)
- Régis Dieckmann
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
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27
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Tsiavaliaris G, Fujita-Becker S, Dürrwang U, Diensthuber RP, Geeves MA, Manstein DJ. Mechanism, regulation, and functional properties of Dictyostelium myosin-1B. J Biol Chem 2007; 283:4520-7. [PMID: 18089562 DOI: 10.1074/jbc.m708113200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myosin-1B is one of three long tailed class-1 myosins containing an ATP-insensitive actin-binding site in the tail region that are produced in Dictyostelium discoideum. Myosin-1B localizes to actin-rich structures at the leading edge of migrating cells where it has been implicated in the formation and retraction of membrane projections, the recycling of plasma membrane components, and intracellular particle transport. Here, we have used a combination of molecular engineering approaches to describe the kinetic and motile properties of the myosin-1B motor and its regulation by TEDS site phosphorylation. Our results show that myosin-1B is a low duty ratio motor and displays the fastest nucleotide binding kinetics of any of the Dictyostelium class-1 myosins studied so far. Different from Dictyostelium myosin-1D and myosin-1E, dephosphorylated myosin-1B is not inactivated but moves actin filaments efficiently, albeit at an up to 8-fold slower velocity in the in vitro motility assay. A further difference is that myosin-1B lacks the ability to switch between rapid movement and bearing tension upon physiological changes of free Mg2+ ions. In this respect, its motor properties appear to be more closely related to Dictyostelium myosin-2 and rabbit skeletal muscle myosin.
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Affiliation(s)
- Georgios Tsiavaliaris
- Institute for Biophysical Chemistry, OE 4350, Hannover Medical School, Carl-Neuberg-Strasse 1, D-30623 Hannover, Germany.
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28
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Berry CC, de la Fuente JM, Mullin M, Wai Ling Chu S, Curtis ASG. Notice of Violation of IEEE Publication Principles Nuclear Localization of HIV-1 Tat Functionalized Gold Nanoparticles. IEEE Trans Nanobioscience 2007; 6:262-9. [DOI: 10.1109/tnb.2007.908973] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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29
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Abstract
Starving, highly motile Dictyostelium cells maintain an active endocytic cycle, taking up their surface about every 11 minutes. Cell motility depends on a functional NSF (N-ethylmaleimide sensitive factor) protein--also essential for endocytosis and membrane trafficking generally--and we, therefore, investigated possible ways in which the endocytic cycle might be required for cell movement. First, NSF, and presumably membrane trafficking, are not required for the initial polarization of the leading edge in a cyclic-AMP gradient. Second, we can detect no evidence for membrane flow from the leading edge, as photobleached or photoactivated marks in the plasma membrane move forward roughly in step with the leading edge, rather than backwards from it. Third, we find that the surface area of a cell--measured from confocal reconstructions--constantly fluctuates during movement as it projects pseudopodia and otherwise changes shape; increases of 20-30% can often occur over a few minutes. These fluctuations cannot be explained by reciprocal changes in filopodial surface area and they substantially exceed the 2-3% by which membranes can stretch. We propose that the endocytic cycle has a key function in motility by allowing adjustment of cell surface area to match changes in shape and that, without this function, movement is severely impaired.
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Affiliation(s)
- David Traynor
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 0QH, UK
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30
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Abstract
Early in evolution, the diversification of membrane-bound compartments that characterize eukaryotic cells was accompanied by the elaboration of molecular machineries that mediate intercompartmental communication and deliver materials to specific destinations. Molecular motors that move on tracks of actin filaments or microtubules mediate the movement of organelles and transport between compartments. The subjects of this review are the motors that power the transport steps along the endocytic and recycling pathways, their modes of attachment to cargo and their regulation.
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Affiliation(s)
- Thierry Soldati
- Départment de Biochimie, Faculté des Sciences, Université de Genève, 30 quai Ernest Ansermet, Sciences II, CH-1211-Genève-4, Switzerland.
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31
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Mercanti V, Charette SJ, Bennett N, Ryckewaert JJ, Letourneur F, Cosson P. Selective membrane exclusion in phagocytic and macropinocytic cups. J Cell Sci 2006; 119:4079-87. [PMID: 16968738 DOI: 10.1242/jcs.03190] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Specialized eukaryotic cells can ingest large particles and sequester them within membrane-delimited phagosomes. Many studies have described the delivery of lysosomal proteins to the phagosome, but little is known about membrane sorting during the early stages of phagosome formation. Here we used Dictyostelium discoideum amoebae to analyze the membrane composition of newly formed phagosomes. The membrane delimiting the closing phagocytic cup was essentially derived from the plasma membrane, but a subgroup of proteins was specifically excluded. Interestingly the same phenomenon was observed during the formation of macropinosomes, suggesting that the same sorting mechanisms are at play during phagocytosis and macropinocytosis. Analysis of mutant strains revealed that clathrin-associated adaptor complexes AP-1, -2 and -3 were not necessary for this selective exclusion and, accordingly, ultrastructural analysis revealed no evidence for vesicular transport around phagocytic cups. Our results suggest the existence of a new, as yet uncharacterized, sorting mechanism in phagocytic and macropinocytic cups.
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Affiliation(s)
- Valentina Mercanti
- Université de Genève, Centre Médical Universitaire, Département de Physiologie Cellulaire et Métabolisme, 1 rue Michel Servet, CH-1211 Genève 4, Switzerland
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Charette SJ, Mercanti V, Letourneur F, Bennett N, Cosson P. A role for adaptor protein-3 complex in the organization of the endocytic pathway in Dictyostelium. Traffic 2006; 7:1528-38. [PMID: 17010123 DOI: 10.1111/j.1600-0854.2006.00478.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Dictyostelium discoideum cells continuously internalize extracellular material, which accumulates in well-characterized endocytic vacuoles. In this study, we describe a new endocytic compartment identified by the presence of a specific marker, the p25 protein. This compartment presents features reminiscent of mammalian recycling endosomes: it is localized in the pericentrosomal region but distinct from the Golgi apparatus. It specifically contains surface proteins that are continuously endocytosed but rapidly recycled to the cell surface and thus absent from maturing endocytic compartments. We evaluated the importance of each clathrin-associated adaptor complex in establishing a compartmentalized endocytic system by studying the phenotype of the corresponding mutants. In knockout cells for mu3, a subunit of the AP-3 clathrin-associated complex, membrane proteins normally restricted to p25-positive endosomes were mislocalized to late endocytic compartments. Our results suggest that AP-3 plays an essential role in the compartmentalization of the endocytic pathway in Dictyostelium.
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Affiliation(s)
- Steve J Charette
- Université de Genève, Centre Médical Universitaire, Département de Physiologie Cellulaire et Métabolisme, 1 rue Michel Servet, CH-1211 Genève 4, Switzerland.
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33
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Gotthardt D, Blancheteau V, Bosserhoff A, Ruppert T, Delorenzi M, Soldati T. Proteomics fingerprinting of phagosome maturation and evidence for the role of a Galpha during uptake. Mol Cell Proteomics 2006; 5:2228-43. [PMID: 16926386 DOI: 10.1074/mcp.m600113-mcp200] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Phagocytosis, whether of food particles in protozoa or bacteria and cell remnants in the metazoan immune system, is a conserved process. The particles are taken up into phagosomes, which then undergo complex remodeling of their components, called maturation. By using two-dimensional gel electrophoresis and mass spectrometry combined with genomic data, we identified 179 phagosomal proteins in the amoeba Dictyostelium, including components of signal transduction, membrane traffic, and the cytoskeleton. By carrying out this proteomics analysis over the course of maturation, we obtained time profiles for 1,388 spots and thus generated a dynamic record of phagosomal protein composition. Clustering of the time profiles revealed five clusters and 24 functional groups that were mapped onto a flow chart of maturation. Two heterotrimeric G protein subunits, Galpha4 and Gbeta, appeared at the earliest times. We showed that mutations in the genes encoding these two proteins produce a phagocytic uptake defect in Dictyostelium. This analysis of phagosome protein dynamics provides a reference point for future genetic and functional investigations.
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Affiliation(s)
- Daniel Gotthardt
- Department of Molecular Cell Research, Max Planck Institute for Medical Research, University Hospital of Heidelberg, Germany
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34
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Charette SJ, Cosson P. Exocytosis of late endosomes does not directly contribute membrane to the formation of phagocytic cups or pseudopods in Dictyostelium. FEBS Lett 2006; 580:4923-8. [PMID: 16920105 DOI: 10.1016/j.febslet.2006.08.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Revised: 07/19/2006] [Accepted: 08/01/2006] [Indexed: 11/20/2022]
Abstract
Exocytosis of late endocytic compartments in Dictyostelium has mostly been studied by live microscopy. Here we show that this exocytosis is accompanied by a complete fusion of late endosomes with the plasma membrane resulting in the transient formation of membrane microdomains that can be visualized by immunofluorescence in fixed cells. This permitted to demonstrate that fusion of late endocytic compartments with the cell surface does not occur in regions of the plasma membrane engaged in the formation of pseudopods, macropinosomes or phagosomes. Our results propose that exocytosis of late endosomes and actin-driven membrane remodeling are mutually exclusive processes.
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Affiliation(s)
- Steve J Charette
- Université de Genève, Centre Médical Universitaire, Département de physiologie cellulaire et métabolisme, 1 rue Michel Servet, CH-1211 Geneva 4, Switzerland.
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35
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Grosshans BL, Grötsch H, Mukhopadhyay D, Fernández IM, Pfannstiel J, Idrissi FZ, Lechner J, Riezman H, Geli MI. TEDS site phosphorylation of the yeast myosins I is required for ligand-induced but not for constitutive endocytosis of the G protein-coupled receptor Ste2p. J Biol Chem 2006; 281:11104-14. [PMID: 16478726 DOI: 10.1074/jbc.m508933200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The yeast myosins I Myo3p and Myo5p have well established functions in the polarization of the actin cytoskeleton and in the endocytic uptake of the G protein-coupled receptor Ste2p. A number of results suggest that phosphorylation of the conserved TEDS serine of the myosin I motor head by the Cdc42p activated p21-activated kinases Ste20p and Cla4p is required for the organization of the actin cytoskeleton. However, the role of this signaling cascade in the endocytic uptake has not been investigated. Interestingly, we find that Myo5p TEDS site phosphorylation is not required for slow, constitutive endocytosis of Ste2p, but it is essential for rapid, ligand-induced internalization of the receptor. Our results strongly suggest that a kinase activates the myosins I to sustain fast endocytic uptake. Surprisingly, however, despite the fact that only p21-activated kinases are known to phosphorylate the conserved TEDS site, we find that these kinases are not essential for ligand-induced internalization of Ste2p. Our observations indicate that a different signaling cascade, involving the yeast homologues of the mammalian PDK1 (3-phosphoinositide-dependent-protein kinase-1), Phk1p and Pkh2p, and serum and glucocorticoid-induced kinase, Ypk1p and Ypk2p, activate Myo3p and Myo5p for their endocytic function.
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Affiliation(s)
- Bianka L Grosshans
- Biochemie-Zentrum Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
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Pujals S, Fernández-Carneado J, López-Iglesias C, Kogan MJ, Giralt E. Mechanistic aspects of CPP-mediated intracellular drug delivery: relevance of CPP self-assembly. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:264-79. [PMID: 16545772 DOI: 10.1016/j.bbamem.2006.01.006] [Citation(s) in RCA: 172] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Revised: 01/03/2006] [Accepted: 01/04/2006] [Indexed: 02/03/2023]
Abstract
In recent years, cell-penetrating peptides have proven to be an efficient intracellular delivery system. The mechanism for CPP internalisation, which first involves interaction with the extracellular matrix, is followed in most cases by endocytosis and finally, depending on the type of endocytosis, an intracellular fate is reached. Delivery of cargo attached to a CPP requires endosomal release, for which different methods have recently been proposed. Positively charged amino acids, hydrophobicity and/or amphipathicity are common to CPPs. Moreover, some CPPs can self-assemble. Herein is discussed the role of self assembly in the cellular uptake of CPPs. Sweet Arrow Peptide (SAP) CPP has been shown to aggregate by CD and TEM (freeze-fixation/freeze-drying), although the internalised species have yet to be identified as either the monomer or an aggregate.
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Affiliation(s)
- Sílvia Pujals
- Institut de Recerca Biomèdica de Barcelona, Parc Científic de Barcelona, Josep Samitier 1-5, E-08028 Barcelona, Spain
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Salas-Cortes L, Ye F, Tenza D, Wilhelm C, Theos A, Louvard D, Raposo G, Coudrier E. Myosin Ib modulates the morphology and the protein transport within multi-vesicular sorting endosomes. J Cell Sci 2006; 118:4823-32. [PMID: 16219689 DOI: 10.1242/jcs.02607] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Members of at least four classes of myosin (I, II, V and VI) have been implicated in the dynamics of a large variety of organelles. Despite their common motor domain structure, some of these myosins, however, are non processive and cannot move organelles along the actin tracks. Here, we demonstrate in the human pigmented MNT-1 cell line that, (1) the overexpression of one of these myosins, myosin 1b, or the addition of cytochalasin D affects the morphology of the sorting multivesicular endosomes; (2) the overexpression of myosin 1b delays the processing of Pmel17 (the product of murine silver locus also named GP100), which occurs in these multivesicular endosomes; (3) myosin 1b associated with endosomes coimmunoprecipitates with Pmel17. All together, these observations suggest that myosin 1b controls the traffic of protein cargo in multivesicular endosomes most probably through its ability to modulate with actin the morphology of these sorting endosomes.
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Affiliation(s)
- Laura Salas-Cortes
- Institut Curie, CNRS UMR144, 26 rue d'Ulm, 75248, Paris, Cedex 05, France
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Crawley SW, de la Roche MA, Lee SF, Li Z, Chitayat S, Smith SP, Côté GP. Identification and characterization of an 8-kDa light chain associated with Dictyostelium discoideum MyoB, a class I myosin. J Biol Chem 2006; 281:6307-15. [PMID: 16415352 DOI: 10.1074/jbc.m508670200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dictyostelium discoideum MyoB is a single-headed class I myosin. Analysis of purified MyoB by SDS-PAGE indicated the presence of an approximately 9-kDa light chain. A tryptic digest of MyoB yielded a partial sequence for the light chain that exactly matched a sequence in a 73-amino acid, 8,296-Da protein (dictyBase number DDB0188713). This protein, termed MlcB, contains two EF-hand motifs and shares approximately 30% sequence identity with the N- and C-terminal lobes of calmodulin. FLAG-MlcB expressed in Dictyostelium co-immunoprecipitated with MyoB but not with the related class myosins and MyoD. Recombinant MlcB bound Ca2+ with a Kd value of 0.2 microm and underwent a Ca2+-induced change in conformation that increased alpha-helical content and surface hydrophobicity. Mutational analysis showed that the first EF-hand was responsible for Ca2+ binding. In the presence and absence of Ca2+ MlcB was a monomer in solution and bound to a MyoB IQ motif peptide with a Kd value of approximately 0.5 microm. A MyoB head-neck construct with a Ser to Glu mutation at the TEDS site bound MlcB and displayed an actin-activated Mg2+ ATPase activity that was insensitive to Ca2+. We conclude that MlcB represents a novel type of small myosin light chain that binds to IQ motifs in a manner comparable with a single lobe of a typical four-EF-hand protein.
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Affiliation(s)
- Scott W Crawley
- Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada
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Damer CK, Bayeva M, Hahn ES, Rivera J, Socec CI. Copine A, a calcium-dependent membrane-binding protein, transiently localizes to the plasma membrane and intracellular vacuoles in Dictyostelium. BMC Cell Biol 2005; 6:46. [PMID: 16343335 PMCID: PMC1327671 DOI: 10.1186/1471-2121-6-46] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2005] [Accepted: 12/12/2005] [Indexed: 01/18/2023] Open
Abstract
Background Copines are soluble, calcium-dependent membrane binding proteins found in a variety of organisms. Copines are characterized as having two C2 domains at the N-terminal region followed by an "A domain" at the C-terminal region. The "A domain" is similar in sequence to the von Willebrand A (VWA) domain found in integrins. The presence of C2 domains suggests that copines may be involved in cell signaling and/or membrane trafficking pathways. Results We have identified six copines genes in the Dictyostelium discoideum genome, cpnA-cpnF, and have focused our studies on cpnA. CpnA is expressed throughout development and was shown to be capable of binding to membranes in a calcium-dependent manner in vitro. A GFP-tagged CpnA was also capable of binding to membranes in a calcium-dependent manner in vitro. In live wildtype Dictyostelium cells expressing GFP-CpnA, GFP-CpnA was typically found in the cytoplasm without any specific localization to membranes. However, in a small subset of starved cells, GFP-CpnA was observed to bind transiently (typically ~1–10 s) to the plasma membrane and intracellular vacuoles. In some cells, the transient membrane localization of GFP-CpnA was observed to occur multiple times in an oscillatory manner over several minutes. In plasma membrane disrupted cells, GFP-CpnA was observed to associate with the plasma membrane and intracellular vacuoles in a calcium-dependent manner. In fixed cells, GFP-CpnA labeled the plasma membrane and intracellular vacuoles, including contractile vacuoles, organelles of the endolysosomal pathway, and phagosomes. Conclusion Our results show that Dictyostelium has multiple copine homologs and provides an excellent system in which to study copine function. The localization of a GFP-tagged CpnA to the plasma membrane, contractile vacuoles, organelles of the endolysosomal pathway, and phagosomes suggests that CpnA may have a role in the function of these organelles or the trafficking to and from them. In addition, we hypothesize that the observed transient oscillatory membrane localization of GFP-CpnA in a small subset of starved cells is caused by fast calcium waves and speculate that CpnA may have a role in development, particularly in the differentiation of stalk cells.
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Affiliation(s)
- Cynthia K Damer
- Biology Department, Vassar College, 124 Raymond Ave., Poughkeepsie, NY 12604
| | - Marina Bayeva
- Biology Department, Vassar College, 124 Raymond Ave., Poughkeepsie, NY 12604
| | - Emily S Hahn
- Biology Department, Vassar College, 124 Raymond Ave., Poughkeepsie, NY 12604
| | - Javier Rivera
- Biology Department, Vassar College, 124 Raymond Ave., Poughkeepsie, NY 12604
| | - Catherine I Socec
- Biology Department, Vassar College, 124 Raymond Ave., Poughkeepsie, NY 12604
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Elbim C, Guichard C, Dang PMC, Fay M, Pedruzzi E, Demur H, Pouzet C, El Benna J, Gougerot-Pocidalo MA. Interleukin-18 primes the oxidative burst of neutrophils in response to formyl-peptides: role of cytochrome b558 translocation and N-formyl peptide receptor endocytosis. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2005; 12:436-46. [PMID: 15753257 PMCID: PMC1065204 DOI: 10.1128/cdli.12.3.436-446.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Using flow cytometry, we observed that interleukin-18 (IL-18) primed human neutrophils (PMNs) in whole blood to produce superoxide anion (O2 degrees-) in response to N-formyl peptide (fMLP) stimulation, whereas IL-18 alone had no significant effect. In contrast to tumor necrosis factor alpha (TNF-alpha), which is a cytokine known to strongly prime O2 degrees- production, IL-18 did not induce either p47phox phosphorylation or its translocation from the cytosol to the plasma membrane. However, IL-18 increased PMN degranulation, as shown by increased levels of cytochrome b558 and CD11b expression at the PMN surface. Moreover, addition of IL-18 to whole blood for 45 min reduced the ability of PMNs to bind to fMLP, suggesting endocytosis of fMLP receptors, as visualized by confocal microscopy. 2,3-Butanedione 2-monoxime, which inhibits endosomal recycling of plasma membrane components back to the cell surface, concomitantly accentuated the diminution of fMLP binding at the PMN surface and increased IL-18 priming of O2 degrees- production by PMNs in response to fMLP. This suggests that fMLP receptor endocytosis could account, at least in part, for the priming of O2 degrees- production. In addition, genistein, a tyrosine kinase inhibitor, and SB203580, a p38 mitogen-activated protein kinase (p38MAPK) inhibitor, completely reversed the decreased level of fMLP binding and increased the level of CD11b expression after IL-18 treatment. Flow cytometric analysis of intact PMNs in whole blood showed that IL-18 increased p38MAPK phosphorylation and tyrosine phosphorylation. In particular, IL-18 induced phosphorylation of focal adhesion kinase (p125FAK), which has been implicated in cytoskeleton reorganization. Taken together, our findings suggest several mechanisms that are likely to regulate cytokine-induced priming of the oxidative burst in PMNs in their blood environment.
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Affiliation(s)
- Carole Elbim
- Unité INSERM U479, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, 75877 Paris Cedex 18, France
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Yan Q, Sun W, Kujala P, Lotfi Y, Vida TA, Bean AJ. CART: an Hrs/actinin-4/BERP/myosin V protein complex required for efficient receptor recycling. Mol Biol Cell 2005; 16:2470-82. [PMID: 15772161 PMCID: PMC1087250 DOI: 10.1091/mbc.e04-11-1014] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Altering the number of surface receptors can rapidly modulate cellular responses to extracellular signals. Some receptors, like the transferrin receptor (TfR), are constitutively internalized and recycled to the plasma membrane. Other receptors, like the epidermal growth factor receptor (EGFR), are internalized after ligand binding and then ultimately degraded in the lysosome. Routing internalized receptors to different destinations suggests that distinct molecular mechanisms may direct their movement. Here, we report that the endosome-associated protein hrs is a subunit of a protein complex containing actinin-4, BERP, and myosin V that is necessary for efficient TfR recycling but not for EGFR degradation. The hrs/actinin-4/BERP/myosin V (CART [cytoskeleton-associated recycling or transport]) complex assembles in a linear manner and interrupting binding of any member to its neighbor produces an inhibition of transferrin recycling rate. Disrupting the CART complex results in shunting receptors to a slower recycling pathway that involves the recycling endosome. The novel CART complex may provide a molecular mechanism for the actin-dependence of rapid recycling of constitutively recycled plasma membrane receptors.
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Affiliation(s)
- Qing Yan
- Department of Neurobiology and Anatomy, University of Texas Medical School, Houston, TX 77030, USA
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42
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Oberholzer U, Iouk TL, Thomas DY, Whiteway M. Functional characterization of myosin I tail regions in Candida albicans. EUKARYOTIC CELL 2005; 3:1272-86. [PMID: 15470256 PMCID: PMC522603 DOI: 10.1128/ec.3.5.1272-1286.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The molecular motor myosin I is required for hyphal growth in the pathogenic yeast Candida albicans. Specific myosin I functions were investigated by a deletion analysis of five neck and tail regions. Hyphal formation requires both the TH1 region and the IQ motifs. The TH2 region is important for optimal hyphal growth. All of the regions, except for the SH3 and acidic (A) regions that were examined individually, were required for the localization of myosin I at the hyphal tip. Similarly, all of the domains were required for the association of myosin I with pelletable actin-bound complexes. Moreover, the hyphal tip localization of cortical actin patches, identified by both rhodamine-phalloidin staining and Arp3-green fluorescent protein signals, was dependent on myosin I. Double deletion of the A and SH3 domains depolarized the distribution of the cortical actin patches without affecting the ability of the mutant to form hyphae, suggesting that myosin I has distinct functions in these processes. Among the six myosin I tail domain mutants, the ability to form hyphae was strictly correlated with endocytosis. We propose that the uptake of cell wall remodeling enzymes and excess plasma membrane is critical for hyphal formation.
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Affiliation(s)
- Ursula Oberholzer
- Genetics Group, Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec H3A 2B2, Canada.
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43
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Hosein RE, Williams SA, Gavin RH. Directed motility of phagosomes inTetrahymena thermophila requires actin and Myo1p, a novel unconventional myosin. ACTA ACUST UNITED AC 2005; 61:49-60. [PMID: 15810016 DOI: 10.1002/cm.20065] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The phagosome cycle was investigated in Tetrahymena thermophila, which had internalized fluorescent latex beads. Confocal microscopy of cells from a GFP-actin strain revealed actin filaments that extended 3-5 mum from the periphery of fluorescent phagosomes. In GFP-actin cells and in wild-type cells, motility of fluorescent phagosomes was directed from the oral cavity to the posterior end of the cell. Although 60% of fluorescent phagosomes in the MYO1-knockout strain were motile, movement of phagosomes was not directed toward the posterior end of the cell and was random. Forty percent of fluorescent phagosomes in knockout cells were non-motile in contrast to only 20% non-motile phagosomes in wild-type cells. The increased incidence of non-motile phagosomes in the knockout strain could reflect absence of Myo1p as a motor. Another myosin or other molecular motors could power random movement of phagosomes in the MYO1-knockout strain. In latrunculin-treated GFP-actin cells, movement of fluorescent phagosomes was random. Average velocity of random movement of fluorescent phagosomes in the knockout strain and in latrunculin-treated cells was statistically the same as the average velocity (2.0 +/- 1.9 microm/min) of phagosomes in GFP-actin cells. These findings are an indication that dynamic actin and Myo1p are required for directed motility of phagosomes.
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Affiliation(s)
- Roland E Hosein
- Department of Biology, Brooklyn College of the City University of New York, Brooklyn, New York 11210, USA
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Kjeken R, Egeberg M, Habermann A, Kuehnel M, Peyron P, Floetenmeyer M, Walther P, Jahraus A, Defacque H, Kuznetsov SA, Griffiths G. Fusion between phagosomes, early and late endosomes: a role for actin in fusion between late, but not early endocytic organelles. Mol Biol Cell 2003; 15:345-58. [PMID: 14617814 PMCID: PMC307552 DOI: 10.1091/mbc.e03-05-0334] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Actin is implicated in membrane fusion, but the precise mechanisms remain unclear. We showed earlier that membrane organelles catalyze the de novo assembly of F-actin that then facilitates the fusion between latex bead phagosomes and a mixture of early and late endocytic organelles. Here, we correlated the polymerization and organization of F-actin with phagosome and endocytic organelle fusion processes in vitro by using biochemistry and light and electron microscopy. When membrane organelles and cytosol were incubated at 37 degrees C with ATP, cytosolic actin polymerized rapidly and became organized into bundles and networks adjacent to membrane organelles. By 30-min incubation, a gel-like state was formed with little further polymerization of actin thereafter. Also during this time, the bulk of in vitro fusion events occurred between phagosomes/endocytic organelles. The fusion between latex bead phagosomes and late endocytic organelles, or between late endocytic organelles themselves was facilitated by actin, but we failed to detect any effect of perturbing F-actin polymerization on early endosome fusion. Consistent with this, late endosomes, like phagosomes, could nucleate F-actin, whereas early endosomes could not. We propose that actin assembled by phagosomes or late endocytic organelles can provide tracks for fusion-partner organelles to move vectorially toward them, via membrane-bound myosins, to facilitate fusion.
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Affiliation(s)
- Rune Kjeken
- European Molecular Biology Laboratory, D-69117 Heidelberg, Germany.
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45
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Remacle A, Murphy G, Roghi C. Membrane type I-matrix metalloproteinase (MT1-MMP) is internalised by two different pathways and is recycled to the cell surface. J Cell Sci 2003; 116:3905-16. [PMID: 12915589 DOI: 10.1242/jcs.00710] [Citation(s) in RCA: 212] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Membrane type 1-matrix metalloproteinase (MT1-MMP) is an integral type I transmembrane multidomain zinc-dependent endopeptidase involved in extracellular matrix remodelling in physiological as well as pathological processes. MT1-MMP participates in the regulated turnover of various extracellular matrix components as well as the activation of secreted metalloproteinases and the cleavage of various cell membrane components. MT1-MMP expression has been reported to correlate with the malignancy of various tumour types and is thought to be an important mediator of cell migration and invasion. Recently, it has been proposed that internalisation of the enzyme from the cell surface is a major short-term level of MT1-MMP regulation controlling the net amount of active enzyme present at the plasma membrane. In this paper we show that, in HT1080 fibrosarcoma cells, MT1-MMP is internalised from the cell surface and colocalises with various markers of the endocytic compartment. Interestingly, we observed that in these cells, internalisation occurs by a combination of both clathrin-mediated and -independent pathways, most probably involving caveolae. In addition, internalised MT1-MMP is recycled to the cell surface, which could, in addition to downregulation of the enzymatic activity, represent a rapid response mechanism used by the cell for relocalising active MT1-MMP at the leading edge during migration.
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Affiliation(s)
- Albert Remacle
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
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Abstract
Ever since the discovery of class I myosins, the first nonmuscle myosins, about 30 years ago, the history of unconventional myosins has been linked to the organization and working of actin filaments. It slowly emerged from studies of class I myosins in lower eukaryotes that they are involved in mechanisms of endocytosis. Most interestingly, a flurry of recent findings assign a more active role to class I myosins in regulating the spatial and temporal organization of actin filament nucleation and elongation. The results highlight the multiple links between class I myosins and the major actin nucleator, the Arp2/3 complex, and its newly described activators. Two additional types of unconventional myosins, myosinIX, and Dictyostelium discoideum MyoM, have recently been tied to the signaling pathways controlling actin cytoskeleton remodeling. The present review surveys the links between these three classes of molecular motors and the complex cellular processes of endocytosis and actin dynamics, and concentrates on a working model accounting for the function of class I myosins via recruitment of the machinery responsible for actin nucleation and elongation.
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Affiliation(s)
- Thierry Soldati
- Department of Biological Sciences, Sir Alexander Fleming Building, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
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Abstract
Endocytosis in protozoa is often regarded as largely different from the pathways operating in mammalian cells. Experiments in the amoeba Dictyostelium, one of the genetically tractable single-celled organisms, have allowed us to manipulate the flow through endocytic compartments and to study the dynamic distribution of molecules by means of green fluorescent protein fusions. This review attempts to compile the molecular data available from Dictyostelium and assign them to specific steps of internalization by phagocytosis or macropinocytosis and to subsequent stages of the endocytic pathway. Parallels to phagocytes of the mammalian immune system are emphasized. The major distinctive feature between mammalian phagocytes and free-living cells is the need for osmoregulation. Therefore Dictyostelium cells possess a contractile vacuole that has occasionally obscured analysis of endocytosis but is now found to be entirely separate from endocytic organelles. In conclusion, the potential of Dictyostelium amoebas to provide a model system of mammalian phagocytes is ever increasing.
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Affiliation(s)
- Markus Maniak
- Department of Cell Biology, Universitaet Kassel, 34109 Kassel, Germany
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HIRATA H, OHKI K, MIYATA H. Change of the Topography of Ventral Cell Surface during Spreading of Fibroblasts as Revealed by Evanescent Wave-Excited Fluorescence Microscopy: Effect of Contractility and Microtubule Integrity. ACTA ACUST UNITED AC 2003. [DOI: 10.1299/jsmec.46.1208] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Hiroaki HIRATA
- Physics Department, Graduate School of Science, Tohoku University
| | - Kazuo OHKI
- Physics Department, Graduate School of Science, Tohoku University
| | - Hidetake MIYATA
- Physics Department, Graduate School of Science, Tohoku University
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49
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Abstract
The endocytic pathway in Dictyostelium appears as a short circuit between endocytosis and exocytosis. Within the hour that elapses between internalization of nutrients and release of remnants, digestion by lysosomal enzymes occurs. Meanwhile, the maturing endosome undergoes a complex series of fusion and fission events, which change its character profoundly and which are far from being fully understood. This review attempts to order the dynamic events into a sequence of stages that is most consistent with present knowledge.
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Affiliation(s)
- Markus Maniak
- Abt. Zellbiologie, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany.
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Bose A, Guilherme A, Robida SI, Nicoloro SMC, Zhou QL, Jiang ZY, Pomerleau DP, Czech MP. Glucose transporter recycling in response to insulin is facilitated by myosin Myo1c. Nature 2002; 420:821-4. [PMID: 12490950 DOI: 10.1038/nature01246] [Citation(s) in RCA: 211] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2002] [Accepted: 10/10/2002] [Indexed: 01/18/2023]
Abstract
Insulin stimulates glucose uptake in muscle and adipocytes by signalling the translocation of GLUT4 glucose transporters from intracellular membranes to the cell surface. The translocation of GLUT4 may involve signalling pathways that are both independent of and dependent on phosphatidylinositol-3-OH kinase (PI(3)K). This translocation also requires the actin cytoskeleton, and the rapid movement of GLUT4 along linear tracks may be mediated by molecular motors. Here we report that the unconventional myosin Myo1c is present in GLUT4-containing vesicles purified from 3T3-L1 adipocytes. Myo1c, which contains a motor domain, three IQ motifs and a carboxy-terminal cargo domain, is highly expressed in primary and cultured adipocytes. Insulin enhances the localization of Myo1c with GLUT4 in cortical tubulovesicular structures associated with actin filaments, and this colocalization is insensitive to wortmannin. Insulin-stimulated translocation of GLUT4 to the adipocyte plasma membrane is augmented by the expression of wild-type Myo1c and inhibited by a dominant-negative cargo domain of Myo1c. A decrease in the expression of endogenous Myo1c mediated by small interfering RNAs inhibits insulin-stimulated uptake of 2-deoxyglucose. Thus, myosin Myo1c functions in a PI(3)K-independent insulin signalling pathway that controls the movement of intracellular GLUT4-containing vesicles to the plasma membrane.
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Affiliation(s)
- Avirup Bose
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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