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Hayes GL, Brown FC, Haas AK, Nottingham RM, Barr FA, Pfeffer SR. Multiple Rab GTPase binding sites in GCC185 suggest a model for vesicle tethering at the trans-Golgi. Mol Biol Cell 2009; 20:209-17. [PMID: 18946081 PMCID: PMC2613123 DOI: 10.1091/mbc.e08-07-0740] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 09/22/2008] [Accepted: 10/14/2008] [Indexed: 12/18/2022] Open
Abstract
GCC185, a trans-Golgi network-localized protein predicted to assume a long, coiled-coil structure, is required for Rab9-dependent recycling of mannose 6-phosphate receptors (MPRs) to the Golgi and for microtubule nucleation at the Golgi via CLASP proteins. GCC185 localizes to the Golgi by cooperative interaction with Rab6 and Arl1 GTPases at adjacent sites near its C terminus. We show here by yeast two-hybrid and direct biochemical tests that GCC185 contains at least four additional binding sites for as many as 14 different Rab GTPases across its entire length. A central coiled-coil domain contains a specific Rab9 binding site, and functional assays indicate that this domain is important for MPR recycling to the Golgi complex. N-Terminal coiled-coils are also required for GCC185 function as determined by plasmid rescue after GCC185 depletion by using small interfering RNA in cultured cells. Golgi-Rab binding sites may permit GCC185 to contribute to stacking and lateral interactions of Golgi cisternae as well as help it function as a vesicle tether.
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Affiliation(s)
- Garret L. Hayes
- *Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305; and
| | - Frank C. Brown
- *Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305; and
| | - Alexander K. Haas
- Cancer Research Centre, University of Liverpool, Liverpool L9 3AT, United Kingdom
| | - Ryan M. Nottingham
- *Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305; and
| | - Francis A. Barr
- Cancer Research Centre, University of Liverpool, Liverpool L9 3AT, United Kingdom
| | - Suzanne R. Pfeffer
- *Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305; and
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Abstract
By presenting antigenic peptides on the cell surface, human leukocyte antigen (HLA) class I molecules are critical for immune defense. Their surface density determines, to a large extent, the level of CD8(+) T cell-dependent immune reactions; their loss is a major mechanism of immune escape. Therefore, powerful processes should regulate their surface expression. Here we document the mechanisms used by CD99 to mediate HLA class I modulation. Up-regulation of HLA class I by IFN-gamma requires CD99. In the trans Golgi network (TGN), and up to the cell surface, CD99 and HLA class I are physically associated via their transmembrane domain. CD99 also binds p230/golgin-245, a coiled-coil protein that recycles between the cytosol and buds/vesicles of the TGN and which plays a fundamental role in trafficking transport vesicles. p230/golgin-245 is anchored within TGN membranes via its Golgin-97, RanBP1, IMh1p, P230 (GRIP) domain and the overexpression of which leads to surface and intracellular down-modulation of HLA class I molecules.
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53
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AtGRIP protein locates to the secretory vesicles of trans Golgi-network in Arabidopsis root cap cells. Sci Bull (Beijing) 2008. [DOI: 10.1007/s11434-008-0420-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Gangi Setty SR, Tenza D, Sviderskaya EV, Bennett DC, Raposo G, Marks MS. Cell-specific ATP7A transport sustains copper-dependent tyrosinase activity in melanosomes. Nature 2008; 454:1142-6. [PMID: 18650808 PMCID: PMC2812007 DOI: 10.1038/nature07163] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Accepted: 06/10/2008] [Indexed: 11/08/2022]
Abstract
Copper is a cofactor for many cellular enzymes and transporters. It can be loaded onto secreted and endomembrane cuproproteins by translocation from the cytosol into membrane-bound organelles by ATP7A or ATP7B transporters, the genes for which are mutated in the copper imbalance syndromes Menkes disease and Wilson disease, respectively. Endomembrane cuproproteins are thought to incorporate copper stably on transit through the trans-Golgi network, in which ATP7A accumulates by dynamic cycling through early endocytic compartments. Here we show that the pigment-cell-specific cuproenzyme tyrosinase acquires copper only transiently and inefficiently within the trans-Golgi network of mouse melanocytes. To catalyse melanin synthesis, tyrosinase is subsequently reloaded with copper within specialized organelles called melanosomes. Copper is supplied to melanosomes by ATP7A, a cohort of which localizes to melanosomes in a biogenesis of lysosome-related organelles complex-1 (BLOC-1)-dependent manner. These results indicate that cell-type-specific localization of a metal transporter is required to sustain metallation of an endomembrane cuproenzyme, providing a mechanism for exquisite spatial control of metalloenzyme activity. Moreover, because BLOC-1 subunits are mutated in subtypes of the genetic disease Hermansky-Pudlak syndrome, these results also show that defects in copper transporter localization contribute to hypopigmentation, and hence perhaps other systemic defects, in Hermansky-Pudlak syndrome.
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Affiliation(s)
- Subba Rao Gangi Setty
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, 19104
| | - Danièle Tenza
- Institut Curie, Centre de Recherche, Paris F-75248, France
- Centre National de la Recherche Scientifique, UMR 144, Paris F-75248, France
| | - Elena V. Sviderskaya
- Centre for Molecular and Metabolic Signalling, Division of Basic Medical Sciences, St. George's, University of London, London SW17 0RE, UK
| | - Dorothy C. Bennett
- Centre for Molecular and Metabolic Signalling, Division of Basic Medical Sciences, St. George's, University of London, London SW17 0RE, UK
| | - Graça Raposo
- Institut Curie, Centre de Recherche, Paris F-75248, France
- Centre National de la Recherche Scientifique, UMR 144, Paris F-75248, France
| | - Michael S. Marks
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, 19104
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Pérez-Victoria FJ, Mardones GA, Bonifacino JS. Requirement of the human GARP complex for mannose 6-phosphate-receptor-dependent sorting of cathepsin D to lysosomes. Mol Biol Cell 2008; 19:2350-62. [PMID: 18367545 DOI: 10.1091/mbc.e07-11-1189] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The biosynthetic sorting of acid hydrolases to lysosomes relies on transmembrane, mannose 6-phosphate receptors (MPRs) that cycle between the TGN and endosomes. Herein we report that maintenance of this cycling requires the function of the mammalian Golgi-associated retrograde protein (GARP) complex. Depletion of any of the three GARP subunits, Vps52, Vps53, or Vps54, by RNAi impairs sorting of the precursor of the acid hydrolase, cathepsin D, to lysosomes and leads to its secretion into the culture medium. As a consequence, lysosomes become swollen, likely due to a buildup of undegraded materials. Missorting of cathepsin D in GARP-depleted cells results from accumulation of recycling MPRs in a population of light, small vesicles downstream of endosomes. These vesicles might correspond to intermediates in retrograde transport from endosomes to the TGN. Depletion of GARP subunits also blocks the retrograde transport of the TGN protein, TGN46, and the B subunit of Shiga toxin. These observations indicate that the mammalian GARP complex plays a general role in the delivery of retrograde cargo into the TGN. We also report that a Vps54 mutant protein in the Wobbler mouse strain is active in retrograde transport, thus explaining the viability of these mutant mice.
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Affiliation(s)
- F Javier Pérez-Victoria
- Cell Biology and Metabolism Program, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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Pavelka M, Neumüller J, Ellinger A. Retrograde traffic in the biosynthetic-secretory route. Histochem Cell Biol 2008; 129:277-88. [PMID: 18270728 PMCID: PMC2248610 DOI: 10.1007/s00418-008-0383-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/09/2008] [Indexed: 02/04/2023]
Abstract
In the biosynthetic-secretory route from the rough endoplasmic reticulum, across the pre-Golgi intermediate compartments, the Golgi apparatus stacks, trans Golgi network, and post-Golgi organelles, anterograde transport is accompanied and counterbalanced by retrograde traffic of both membranes and contents. In the physiologic dynamics of cells, retrograde flow is necessary for retrieval of molecules that escaped from their compartments of function, for keeping the compartments' balances, and maintenance of the functional integrities of organelles and compartments along the secretory route, for repeated use of molecules, and molecule repair. Internalized molecules may be transported in retrograde direction along certain sections of the secretory route, and compartments and machineries of the secretory pathway may be misused by toxins. An important example is the toxin of Shigella dysenteriae, which has been shown to travel from the cell surface across endosomes, and the Golgi apparatus en route to the endoplasmic reticulum, and the cytosol, where it exerts its deleterious effects. Most importantly in medical research, knowledge about the retrograde cellular pathways is increasingly being utilized for the development of strategies for targeted delivery of drugs to the interior of cells. Multiple details about the molecular transport machineries involved in retrograde traffic are known; a high number of the molecular constituents have been characterized, and the complicated fine structural architectures of the compartments involved become more and more visible. However, multiple contradictions exist, and already established traffic models again are in question by contradictory results obtained with diverse cell systems, and/or different techniques. Additional problems arise by the fact that the conditions used in the experimental protocols frequently do not reflect the physiologic situations of the cells. Regular and pathologic situations often are intermingled, and experimental treatments by themselves change cell organizations. This review addresses physiologic and pathologic situations, tries to correlate results obtained by different cell biologic techniques, and asks questions, which may be the basis and starting point for further investigations.
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Affiliation(s)
- Margit Pavelka
- Department of Cell Biology and Ultrastructure Research, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, Vienna, Austria.
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Popoff V, Mardones GA, Tenza D, Rojas R, Lamaze C, Bonifacino JS, Raposo G, Johannes L. The retromer complex and clathrin define an early endosomal retrograde exit site. J Cell Sci 2007; 120:2022-31. [PMID: 17550971 DOI: 10.1242/jcs.003020] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Previous studies have indicated a role for clathrin, the clathrin adaptors AP1 and epsinR, and the retromer complex in retrograde sorting from early/recycling endosomes to the trans Golgi network (TGN). However, it has remained unclear whether these protein machineries function on the same or parallel pathways. We show here that clathrin and the retromer subunit Vps26 colocalize at the ultrastructural level on early/recycling endosomes containing Shiga toxin B-subunit, a well-studied retrograde transport cargo. As previously described for clathrin, we find that interfering with Vps26 expression inhibits retrograde transport of the Shiga toxin B-subunit to the TGN. Under these conditions, endosomal tubules that take the Shiga toxin B-subunit out of transferrin-containing early/recycling endosomes appear to be stabilized. This situation differs from that previously described for low-temperature incubation and clathrin-depletion conditions under which Shiga toxin B-subunit labeling was found to overlap with that of the transferrin receptor. In addition, we find that the Shiga toxin B-subunit and the transferrin receptor accumulate close to multivesicular endosomes in clathrin-depleted cells, suggesting that clathrin initiates retrograde sorting on vacuolar early endosomes, and that retromer is then required to process retrograde tubules. Our findings thus establish a role for the retromer complex in retrograde transport of the B-subunit of Shiga toxin, and strongly suggest that clathrin and retromer function in consecutive retrograde sorting steps on early endosomes.
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Affiliation(s)
- Vincent Popoff
- Laboratoire Trafic et Signalisation, UMR144 Curie/CNRS, Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France
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Bujny MV, Popoff V, Johannes L, Cullen PJ. The retromer component sorting nexin-1 is required for efficient retrograde transport of Shiga toxin from early endosome to the trans Golgi network. J Cell Sci 2007; 120:2010-21. [PMID: 17550970 DOI: 10.1242/jcs.003111] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The mammalian retromer complex is a multi-protein complex that regulates retrograde transport of the cation-independent mannose 6-phosphate receptor (CI-MPR) from early endosomes to the trans Golgi network (TGN). It consists of two subcomplexes: a membrane-bound coat comprising sorting nexin-1 (SNX1) and possibly sorting nexin-2 (SNX2), and a cargo-selective subcomplex, composed of VPS26, VPS29 and VPS35. In addition to the retromer, a variety of other protein complexes has been suggested to regulate endosome-to-TGN transport of not only the CI-MPR but a wide range of other cargo proteins. Here, we have examined the role of SNX1 and SNX2 in endosomal sorting of Shiga and cholera toxins, two toxins that undergo endosome-to-TGN transport en route to their cellular targets located within the cytosol. By using small interfering RNA (siRNA)-mediated silencing combined with single-cell fluorescent-toxin-uptake assays and well-established biochemical assays to analyze toxin delivery to the TGN, we have established that suppression of SNX1 leads to a significant reduction in the efficiency of endosome-to-TGN transport of the Shiga toxin B-subunit. Furthermore, we show that for the B subunit of cholera toxin, retrograde endosome-to-TGN transport is less reliant upon SNX1. Overall, our data establish a role for SNX1 in the endosome-to-TGN transport of Shiga toxin and are indicative for a fundamental difference between endosomal sorting of Shiga and cholera toxins into endosome-to-TGN retrograde transport pathways.
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Affiliation(s)
- Miriam V Bujny
- The Henry Wellcome Integrated Signalling Laboratories, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol, BS8 1TD, UK
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59
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Lieu ZZ, Derby MC, Teasdale RD, Hart C, Gunn P, Gleeson PA. The golgin GCC88 is required for efficient retrograde transport of cargo from the early endosomes to the trans-Golgi network. Mol Biol Cell 2007; 18:4979-91. [PMID: 17914056 PMCID: PMC2096601 DOI: 10.1091/mbc.e07-06-0622] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Retrograde transport pathways from early/recycling endosomes to the trans-Golgi network (TGN) are poorly defined. We have investigated the role of TGN golgins in retrograde trafficking. Of the four TGN golgins, p230/golgin-245, golgin-97, GCC185, and GCC88, we show that GCC88 defines a retrograde transport pathway from early endosomes to the TGN. Depletion of GCC88 in HeLa cells by interference RNA resulted in a block in plasma membrane-TGN recycling of two cargo proteins, TGN38 and a CD8 mannose-6-phosphate receptor cytoplasmic tail fusion protein. In GCC88-depleted cells, cargo recycling was blocked in the early endosome. Depletion of GCC88 dramatically altered the TGN localization of the t-SNARE syntaxin 6, a syntaxin required for endosome to TGN transport. Furthermore, the transport block in GCC88-depleted cells was rescued by syntaxin 6 overexpression. Internalized Shiga toxin was efficiently transported from endosomes to the Golgi of GCC88-depleted cells, indicating that Shiga toxin and TGN38 are internalized by distinct retrograde transport pathways. These findings have identified an essential role for GCC88 in the localization of TGN fusion machinery for transport from early endosomes to the TGN, and they have allowed the identification of a retrograde pathway which differentially selects TGN38 and mannose-6-phosphate receptor from Shiga toxin.
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Affiliation(s)
- Zi Zhao Lieu
- *The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia; and
| | - Merran C. Derby
- *The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia; and
| | - Rohan D. Teasdale
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Charles Hart
- *The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia; and
| | - Priscilla Gunn
- *The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia; and
| | - Paul A. Gleeson
- *The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia; and
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60
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Yamane J, Kubo A, Nakayama K, Yuba-Kubo A, Katsuno T, Tsukita S, Tsukita S. Functional involvement of TMF/ARA160 in Rab6-dependent retrograde membrane traffic. Exp Cell Res 2007; 313:3472-85. [PMID: 17698061 DOI: 10.1016/j.yexcr.2007.07.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Revised: 07/10/2007] [Accepted: 07/10/2007] [Indexed: 12/28/2022]
Abstract
The small GTPase Rab6 regulates retrograde membrane traffic from endosomes to the Golgi apparatus and from the Golgi to the endoplasmic reticulum (ER). We examined the role of a Rab6-binding protein, TMF/ARA160 (TATA element modulatory factor/androgen receptor-coactivator of 160 kDa), in this process. High-resolution immunofluorescence imaging revealed that TMF signal surrounded Rab6-positive Golgi structures and immunoelectron microscopy revealed that TMF is concentrated at the budding structures localized at the tips of cisternae. The knockdown of either TMF or Rab6 by RNA interference blocked retrograde transport of endocytosed Shiga toxin from early/recycling endosomes to the trans-Golgi network, causing missorting of the toxin to late endosomes/lysosomes. However, the TMF knockdown caused Rab6-dependent displacement of N-acetylgalactosaminyltransferase-2 (GalNAc-T2), but not beta1,4-galactosyltransferase (GalT), from the Golgi. Analyses using chimeric proteins, in which the cytoplasmic regions of GalNAc-T2 and GalT were exchanged, revealed that the cytoplasmic region of GalNAc-T2 plays a crucial role in its TMF-dependent Golgi retention. These observations suggest critical roles for TMF in two Rab6-dependent retrograde transport processes: one from endosomes to the Golgi and the other from the Golgi to the ER.
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Affiliation(s)
- Junko Yamane
- Department of Cell Biology, Faculty of Medicine, Kyoto University, Kyoto, Japan
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61
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Sbodio JI, Machamer CE. Identification of a redox-sensitive cysteine in GCP60 that regulates its interaction with golgin-160. J Biol Chem 2007; 282:29874-81. [PMID: 17711851 DOI: 10.1074/jbc.m705794200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Golgin-160 is ubiquitously expressed in vertebrates. It localizes to the cytoplasmic side of the Golgi and has a large C-terminal coiled-coil domain. The noncoiled-coil N-terminal head domain contains Golgi targeting information, a cryptic nuclear localization signal, and three caspase cleavage sites. Caspase cleavage of the golgin-160 head domain generates different fragments that can translocate to the nucleus by exposing the nuclear localization signal. We have previously shown that GCP60, a Golgi resident protein, interacts weakly with the golgin-160 head domain but has a strong interaction with one of the caspase-generated golgin-160 fragments (residues 140-311). This preferential interaction increases the Golgi retention of the golgin-160 fragment in cells overexpressing GCP60. Here we studied the interaction of golgin-160-(140-311) with GCP60 and identified a single cysteine residue in GCP60 (Cys-463) that is critical for the interaction of the two proteins. Mutation of the cysteine blocked the interaction in vitro and disrupted the ability to retain the golgin-160 fragment at the Golgi in cells. We also found that Cys-463 is redox-sensitive; in its reduced form, interaction with golgin-160 was diminished or abolished, whereas oxidation of the Cys-463 by hydrogen peroxide restored the interaction. In addition, incubation with a nitric oxide donor promoted this interaction in vitro. These findings suggest that nuclear translocation of golgin-160-(140-311) is a highly coordinated event regulated not only by cleavage of the golgin-160 head but also by the oxidation state of GCP60.
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Affiliation(s)
- Juan I Sbodio
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Saenz JB, Doggett TA, Haslam DB. Identification and characterization of small molecules that inhibit intracellular toxin transport. Infect Immun 2007; 75:4552-61. [PMID: 17576758 PMCID: PMC1951202 DOI: 10.1128/iai.00442-07] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Shiga toxin (Stx), cholera toxin (Ctx), and the plant toxin ricin are among several toxins that reach their intracellular destinations via a complex route. Following endocytosis, these toxins travel in a retrograde direction through the endosomal system to the trans-Golgi network, Golgi apparatus, and endoplasmic reticulum (ER). There the toxins are transported across the ER membrane to the cytosol, where they carry out their toxic effects. Transport via the ER from the cell surface to the cytosol is apparently unique to pathogenic toxins, raising the possibility that various stages in the transport pathway can be therapeutically targeted. We have applied a luciferase-based high-throughput screen to a chemical library of small-molecule compounds in order to identify inhibitors of Stx. We report two novel compounds that protect against Stx and ricin inhibition of protein synthesis, and we demonstrate that these compounds reversibly inhibit bacterial transport at various stages in the endocytic pathway. One compound (compound 75) inhibited transport at an early stage of Stx and Ctx transport and also provided protection against diphtheria toxin, which enters the cytosol from early endosomes. In contrast, compound 134 inhibited transport from recycling endosomes through the Golgi apparatus and protected only against toxins that access the ER. Small-molecule compounds such as these will provide insight into the mechanism of toxin transport and lead to the identification of compounds with therapeutic potential against toxins routed through the ER.
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Affiliation(s)
- Jose B Saenz
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110, USA
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63
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Derby MC, Lieu ZZ, Brown D, Stow JL, Goud B, Gleeson PA. The trans-Golgi Network Golgin, GCC185, is Required for Endosome-to-Golgi Transport and Maintenance of Golgi Structure. Traffic 2007; 8:758-73. [PMID: 17488291 DOI: 10.1111/j.1600-0854.2007.00563.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Four mammalian golgins are specifically targeted to the trans-Golgi network (TGN) membranes via their C-terminal GRIP domains. The TGN golgins, p230/golgin-245 and golgin-97, are recruited via the GTPase Arl1, whereas the TGN golgin GCC185 is recruited independently of Arl1. Here we show that GCC185 is localized to a region of the TGN distinct from Arl1 and plays an essential role in maintaining the organization of the Golgi apparatus. Using both small interfering RNA (siRNA) and microRNA (miRNA), we show that depletion of GCC185 in HeLa cells frequently resulted in fragmentation of the Golgi apparatus. Golgi apparatus fragments were dispersed throughout the cytoplasm and contained both cis and trans markers. Trafficking of anterograde and retrograde cargo was analysed over an extended period following GCC185 depletion. Early effects of GCC185 depletion included a perturbation in the distribution of the mannose-6-phosphate receptor and a block in shiga toxin trafficking to the Golgi apparatus, which occurred in parallel with the fragmentation of the Golgi ribbon. Internalized shiga toxin accumulated in Rab11-positive endosomes, indicating GCC185 is essential for transport between the recycling endosome and the TGN. In contrast, the plasma membrane-TGN recycling protein TGN38 was efficiently transported into GCC185-depleted Golgi apparatus fragments throughout a 96-h period, and anterograde transport of E-cadherin was functional until a late stage of GCC185 depletion. This study demonstrated (i) a more effective long-term depletion of GCC185 using miRNA than siRNA and (ii) a dual role for the GCC185 golgin in the regulation of endosome-to-TGN membrane transport and in the organization of the Golgi apparatus.
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Affiliation(s)
- Merran C Derby
- Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, Victoria 3010, Australia, and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
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Colanzi A, Carcedo CH, Persico A, Cericola C, Turacchio G, Bonazzi M, Luini A, Corda D. The Golgi mitotic checkpoint is controlled by BARS-dependent fission of the Golgi ribbon into separate stacks in G2. EMBO J 2007; 26:2465-76. [PMID: 17431394 PMCID: PMC1868899 DOI: 10.1038/sj.emboj.7601686] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Accepted: 03/21/2007] [Indexed: 11/09/2022] Open
Abstract
The Golgi ribbon is a complex structure of many stacks interconnected by tubules that undergo fragmentation during mitosis through a multistage process that allows correct Golgi inheritance. The fissioning protein CtBP1-S/BARS (BARS) is essential for this, and is itself required for mitotic entry: a block in Golgi fragmentation results in cell-cycle arrest in G2, defining the 'Golgi mitotic checkpoint'. Here, we clarify the precise stage of Golgi fragmentation required for mitotic entry and the role of BARS in this process. Thus, during G2, the Golgi ribbon is converted into isolated stacks by fission of interstack connecting tubules. This requires BARS and is sufficient for G2/M transition. Cells without a Golgi ribbon are independent of BARS for Golgi fragmentation and mitotic entrance. Remarkably, fibroblasts from BARS-knockout embryos have their Golgi complex divided into isolated stacks at all cell-cycle stages, bypassing the need for BARS for Golgi fragmentation. This identifies the precise stage of Golgi fragmentation and the role of BARS in the Golgi mitotic checkpoint, setting the stage for molecular analysis of this process.
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Affiliation(s)
- Antonino Colanzi
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy
- These authors contributed equally to this work
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Via Nazionale, 8/A, Santa Maria Imbaro, Chieti 66030, Italy. Tel.: +39 0872 570353; Fax: +39 0872 570412; E-mail:
| | - Cristina Hidalgo Carcedo
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy
- These authors contributed equally to this work
- Present address: Tumour Cell Biology Laboratory, Cancer Research UK London Research Institute, London WC2A 3PX, UK
| | - Angela Persico
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy
| | - Claudia Cericola
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy
| | - Gabriele Turacchio
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy
| | - Matteo Bonazzi
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy
- Present address: Unité des Interactions Bactéries-Cellules, Institut Pasteur, 75015 Paris, France
| | - Alberto Luini
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy
| | - Daniela Corda
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Via Nazionale, 8/A, Santa Maria Imbaro, Chieti 66030, Italy. Tel.: +39 0872 570353; Fax: +39 0872 570412; E-mail:
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Zahn C, Hommel A, Lu L, Hong W, Walther DJ, Florian S, Joost HG, Schürmann A. Knockout of Arfrp1 leads to disruption of ARF-like1 (ARL1) targeting to the trans-Golgi in mouse embryos and HeLa cells. Mol Membr Biol 2007; 23:475-85. [PMID: 17127620 DOI: 10.1080/09687860600840100] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
ADP-ribosylation factor related protein 1 (ARFRP1) is a member of the ARF-family of GTPases which operate as molecular switches in the regulation of intracellular protein traffic. Deletion of the mouse Arfrp1 gene leads to embryonic lethality during early gastrulation, suggesting that ARFRP1 is required for cell adhesion-related processes. Here we show that ARFRP1 specifically controls targeting of ARL1 and its effector Golgin-245 to the trans-Golgi. GTP-bound ARFRP1 (ARFRP1-Q79L mutant) is associated with Golgi membranes and co-localized with the GTPase ARL1. In contrast, the guanine nucleotide exchange defective ARFRP1 mutant (ARFRP1-T31N) clusters within the cytosol. ARFRP1-T31N or depletion of endogenous ARFRP1 by RNA interference disrupts the Golgi association of ARL1 and of the GRIP-domain protein Golgin-245 and alters the distribution of a trans-Golgi network marker, syntaxin 6. In contrast, the targeting of two other Golgi-associated proteins, GM130 and giantin, was unaffected. Furthermore, in Arfrp1-/ - embryos ARL1 dislocated from Golgi membranes whereas it was associated with intracellular membranes in wild-type embryos. These data suggest that lethality of Arfrp1 knockout embryos is due to a specific disruption of protein targeting, e.g., of ARL1 and Golgin-245, to the Golgi.
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Affiliation(s)
- Claudia Zahn
- Department of Pharmacology, German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal, Germany
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66
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Derby MC, Gleeson PA. New Insights into Membrane Trafficking and Protein Sorting. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 261:47-116. [PMID: 17560280 DOI: 10.1016/s0074-7696(07)61002-x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Protein transport in the secretory and endocytic pathways is a multistep process involving the generation of transport carriers loaded with defined sets of cargo, the shipment of the cargo-loaded transport carriers between compartments, and the specific fusion of these transport carriers with a target membrane. The regulation of these membrane-mediated processes involves a complex array of protein and lipid interactions. As the machinery and regulatory processes of membrane trafficking have been defined, it is increasingly apparent that membrane transport is intimately connected with a number of other cellular processes, such as quality control in the endoplasmic reticulum (ER), cytoskeletal dynamics, receptor signaling, and mitosis. The fidelity of membrane trafficking relies on the correct assembly of components on organelles. Recruitment of peripheral proteins plays a critical role in defining organelle identity and the establishment of membrane subdomains, essential for the regulation of vesicle transport. The molecular mechanisms for the biogenesis of membrane subdomains are also central to understanding how cargo is sorted and segregated and how different populations of transport carriers are generated. In this review we will focus on the emerging themes of organelle identity, membrane subdomains, regulation of Golgi trafficking, and advances in dissecting pathways in physiological systems.
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Affiliation(s)
- Merran C Derby
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
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67
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Hicks SW, Horn TA, McCaffery JM, Zuckerman DM, Machamer CE. Golgin-160 Promotes Cell Surface Expression of the Beta-1 Adrenergic Receptor. Traffic 2006; 7:1666-77. [PMID: 17118120 DOI: 10.1111/j.1600-0854.2006.00504.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Golgin-160 is a ubiquitously expressed peripheral Golgi membrane protein that is important for transduction of certain pro-apoptotic signals at the Golgi complex. However, the role of golgin-160 in normal Golgi structure and function is unknown. Here, we show that depletion of golgin-160 using RNA interference (RNAi) does not affect Golgi morphology or constitutive membrane traffic in HeLa cells. However, depletion of golgin-160 leads to significantly decreased cell surface levels of exogenously expressed beta1-adrenergic receptor (beta1AR), which can be rescued by expression of RNAi-resistant forms of golgin-160. Furthermore, overexpression of golgin-160 leads to higher surface levels of beta1AR. Golgin-160 is localized mostly in the cis and medial regions of the Golgi stack by immunoelectron microscopy, suggesting that it does not directly promote incorporation of beta1AR into transport vesicles at the trans Golgi network. Golgin-160 interacts with beta1AR in vitro, and we mapped the interaction to a region between residues 140 and 257 in the head of golgin-160 and the third intracellular loop of beta1AR. Our results support the idea that golgin-160 may promote efficient surface delivery of a subset of cargo molecules.
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Affiliation(s)
- Stuart W Hicks
- Department of Cell Biology, Johns Hopkins University School of Medicine, 725 Wolfe Street, Baltimore, MD 21205, USA
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68
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Bonifacino JS, Rojas R. Retrograde transport from endosomes to the trans-Golgi network. Nat Rev Mol Cell Biol 2006; 7:568-79. [PMID: 16936697 DOI: 10.1038/nrm1985] [Citation(s) in RCA: 489] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A subset of intracellular transmembrane proteins such as acid-hydrolase receptors, processing peptidases and SNAREs, as well as extracellular protein toxins such as Shiga toxin and ricin, undergoes 'retrograde' transport from endosomes to the trans-Golgi network. Here, we discuss recent studies that have begun to unravel the molecular machinery that is involved in this process. We also propose a central role for a 'tubular endosomal network' in sorting to recycling pathways that lead not only to the trans-Golgi network but also to different plasma-membrane domains and to specialized storage vesicles.
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Affiliation(s)
- Juan S Bonifacino
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
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69
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Liu YW, Lee SW, Lee FJS. Arl1p is involved in transport of the GPI-anchored protein Gas1p from the late Golgi to the plasma membrane. J Cell Sci 2006; 119:3845-55. [PMID: 16926193 DOI: 10.1242/jcs.03148] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The molecular mechanisms involved in the transport of GPI-anchored proteins from the trans-Golgi network (TGN) to the cell periphery have not been established. Arl1p is a member of the Arf-like protein (Arl) subfamily of small GTPases and is localized in the late Golgi. Although Arl1p is implicated in regulation of Golgi structure and function, no endogenous cargo protein that is regulated by Arl1p has been identified in yeast. In this study, we demonstrate that Arl1p is involved in the anterograde transport from the Golgi to the cell surface of the glycosylphosphatidylinositol (GPI)-anchored plasma-membrane-resident protein Gas1p, but not the cell-wall-localized GPI-anchored proteins Crh1p, Crh2p and Cwp1p, or non-GPI-anchored plasma membrane-protein Gap1p. We also show that regulators of Arl1p (Sys1p, Arl3p and Gcs1p) and an effector (Imh1p) all participate in the transport of Gas1p. Thus, we infer that the signaling cascade Sys1p-Arl3p-Arl1p-Imh1p specifically participates in the transport of a GPI-anchored protein from the late Golgi to the plasma membrane.
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Affiliation(s)
- Ya-Wen Liu
- Institute of Molecular Medicine, School of Medicine, National Taiwan University, and Department of Medical Research, National Taiwan University Hospital, Taipei 100, Taiwan
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70
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Caviston JP, Holzbaur ELF. Microtubule motors at the intersection of trafficking and transport. Trends Cell Biol 2006; 16:530-7. [PMID: 16938456 DOI: 10.1016/j.tcb.2006.08.002] [Citation(s) in RCA: 225] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Revised: 07/25/2006] [Accepted: 08/17/2006] [Indexed: 12/19/2022]
Abstract
Molecular motors drive the transport of vesicles and organelles within the cell. Traditionally, these transport processes have been considered separately from membrane trafficking events, such as regulated budding and fusion. However, recent progress has revealed mechanistic links that integrate these processes within the cell. Rab proteins, which function as key regulators of intracellular trafficking, have now been shown to recruit specific motors to organelle membranes. Rab-independent recruitment of motors by adaptor or scaffolding proteins is also a key mechanism. Once recruited to vesicles and organelles, these motors can then drive directed transport; this directed transport could in turn affect the efficiency of trafficking events. Here, we discuss this coordinated regulation of trafficking and transport, which provides a powerful mechanism for temporal and spatial control of cellular dynamics.
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Affiliation(s)
- Juliane P Caviston
- Department of Physiology, University of Pennsylvania School of Medicine, D400 Richards Building, 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA
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71
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Reddy JV, Burguete AS, Sridevi K, Ganley IG, Nottingham RM, Pfeffer SR. A functional role for the GCC185 golgin in mannose 6-phosphate receptor recycling. Mol Biol Cell 2006; 17:4353-63. [PMID: 16885419 PMCID: PMC1635343 DOI: 10.1091/mbc.e06-02-0153] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Mannose 6-phosphate receptors (MPRs) deliver newly synthesized lysosomal enzymes to endosomes and then recycle to the Golgi. MPR recycling requires Rab9 GTPase; Rab9 recruits the cytosolic adaptor TIP47 and enhances its ability to bind to MPR cytoplasmic domains during transport vesicle formation. Rab9-bearing vesicles then fuse with the trans-Golgi network (TGN) in living cells, but nothing is known about how these vesicles identify and dock with their target. We show here that GCC185, a member of the Golgin family of putative tethering proteins, is a Rab9 effector that is required for MPR recycling from endosomes to the TGN in living cells, and in vitro. GCC185 does not rely on Rab9 for its TGN localization; depletion of GCC185 slightly alters the Golgi ribbon but does not interfere with Golgi function. Loss of GCC185 triggers enhanced degradation of mannose 6-phosphate receptors and enhanced secretion of hexosaminidase. These data assign a specific pathway to an interesting, TGN-localized protein and suggest that GCC185 may participate in the docking of late endosome-derived, Rab9-bearing transport vesicles at the TGN.
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Affiliation(s)
- Jonathan V. Reddy
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307
| | | | - Khambhampaty Sridevi
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307
| | - Ian G. Ganley
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307
| | - Ryan M. Nottingham
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307
| | - Suzanne R. Pfeffer
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307
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72
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Hehnly H, Sheff D, Stamnes M. Shiga toxin facilitates its retrograde transport by modifying microtubule dynamics. Mol Biol Cell 2006; 17:4379-89. [PMID: 16885418 PMCID: PMC1635369 DOI: 10.1091/mbc.e06-04-0310] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The bacterial exotoxin Shiga toxin is endocytosed by mammalian host cells and transported retrogradely through the secretory pathway before entering the cytosol. Shiga toxin also increases the levels of microfilaments and microtubules (MTs) upon binding to the cell surface. The purpose for this alteration in cytoskeletal dynamics is unknown. We have investigated whether Shiga toxin-induced changes in MT levels facilitate its intracellular transport. We have tested the effects of the Shiga toxin B subunit (STB) on MT-dependent and -independent transport steps. STB increases the rate of MT-dependent Golgi stack repositioning after nocodazole treatment. It also enhances the MT-dependent accumulation of transferrin in a perinuclear recycling compartment. By contrast, the rate of MT-independent transferrin recycling is not significantly different when STB is present. We found that STB normally requires MTs and dynein for its retrograde transport to the juxtanuclear Golgi complex and that STB increases MT assembly. Furthermore, we find that MT polymerization is limiting for STB transport in cells. These results show that STB-induced changes in cytoskeletal dynamics influence intracellular transport. We conclude that the increased rate of MT assembly upon Shiga toxin binding facilitates the retrograde transport of the toxin through the secretory pathway.
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Affiliation(s)
| | - David Sheff
- Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242
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73
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Ho HH, He CY, de Graffenried CL, Murrells LJ, Warren G. Ordered assembly of the duplicating Golgi in Trypanosoma brucei. Proc Natl Acad Sci U S A 2006; 103:7676-81. [PMID: 16672362 PMCID: PMC1472504 DOI: 10.1073/pnas.0602595103] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The new Golgi in the protozoan parasite Trypanosoma brucei grows near to the old and adjacent to the growing new endoplasmic reticulum exit site. Growth is now shown to be at least a two-stage process, in which a representative matrix marker (GRASP) and enzyme (GntB) are delivered to the site of assembly, followed approximately 10 min later by a COPI component (epsilon-COP) and a trans-Golgi network (TGN) marker (GRIP70). A secretory cargo marker (signal sequence-YFP) appeared early near the new endoplasmic reticulum exit site but did not enter the Golgi until the second stage. Together these data suggest that structural and enzymatic components of the new Golgi stack are laid down first, followed by those needed to move and sort the cargo passing through it.
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Affiliation(s)
- Helen H. Ho
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520
| | - Cynthia Y. He
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520
| | | | - Lindsay J. Murrells
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520
| | - Graham Warren
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520
- *To whom correspondence should be addressed. E-mail:
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74
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Utskarpen A, Slagsvold HH, Iversen TG, Wälchli S, Sandvig K. Transport of Ricin from Endosomes to the Golgi Apparatus is Regulated by Rab6A and Rab6A′. Traffic 2006; 7:663-72. [PMID: 16683916 DOI: 10.1111/j.1600-0854.2006.00418.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Ricin is transported from early endosomes and/or the recycling compartment to the trans-Golgi network (TGN) and subsequently to the endoplasmic recticulum (ER) before it enters the cytosol and intoxicates cells. We have investigated the role of the Rab6 isoforms in retrograde transport of ricin using both oligo- and vector-based RNAi assays. Ricin transport to the TGN was inhibited by the depletion of Rab6A when the Rab6A messenger RNA (mRNA) levels were reduced by more than 40% and less than 75%. However, when Rab6A mRNA was reduced by more than 75% and Rab6A' mRNA was simultaneously up-regulated, the inhibition of ricin sulfation was abolished, indicating that the up-regulation of Rab6A' may compensate for the loss of Rab6A function. In addition, we found that a near complete depletion of Rab6A' gave approximately 40% reduction in ricin sulfation. The up-regulation of Rab6A mRNA levels did not seem to compensate for the loss of Rab6A' function. The depletion of both Rab6A and Rab6A' gave a stronger inhibition of ricin sulfation than what was observed knocking down the two isoforms separately. In conclusion, both Rab6A and Rab6A' seem to be involved in the transport of ricin from endosomes to the Golgi apparatus.
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Affiliation(s)
- Audrun Utskarpen
- Department of Biochemistry, Institute for Cancer Research, Faculty Division The Norwegian Radium Hospital, University of Oslo, Montebello, 0310 Oslo, Norway
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75
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Abstract
Coiled-coil and multisubunit tethers have emerged as key regulators of membrane traffic and organellar architecture. The restricted subcellular localization of tethers and their ability to interact with Rabs and soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) suggests that tethers participate in determining the specificity of membrane fusion. An accepted model of tether function considers them molecular “bridges” that link opposing membranes before SNARE pairing. This model has been extended by findings in various experimental systems, suggesting that tethers may have other functions. Recent reports implicate tethers in the assembly of SNARE complexes, cargo selection and transit, cytoskeletal events, and localized attachment of regulatory proteins. A concept of tethers as scaffolding machines that recruit protein components involved in varied cellular responses is emerging. In this model, tethers function as integration switches that simultaneously transmit information to coordinate distinct processes required for membrane traffic.
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Affiliation(s)
- Elizabeth Sztul
- Dept. of Cell Biology, Univ. of Alabama at Birmingham, 1918 Univ. Blvd., Birmingham, AL 35294, USA.
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76
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Snyder CM, Mardones GA, Ladinsky MS, Howell KE. GMx33 associates with the trans-Golgi matrix in a dynamic manner and sorts within tubules exiting the Golgi. Mol Biol Cell 2005; 17:511-24. [PMID: 16236792 PMCID: PMC1345686 DOI: 10.1091/mbc.e05-07-0682] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The trans-Golgi matrix consists of a group of proteins dynamically associated with the trans-Golgi and thought to be involved in anterograde and retrograde Golgi traffic, as well as interactions with the cytoskeleton and maintenance of the Golgi structure. GMx33 is localized to the cytoplasmic face of the trans-Golgi and is also present in a large cytoplasmic pool. Here we demonstrate that GMx33 is dynamically associated with the trans-Golgi matrix, associating and dissociating with the Golgi in seconds. GMx33 can be locked onto the trans-Golgi matrix by GTPgammaS, indicating that its association is regulated in a GTP-dependent manner like several other Golgi matrix proteins. Using live-cell imaging we show that GMx33 exits the Golgi associated with tubules and within these tubules GMx33 segregates from transmembrane proteins followed by fragmentation of the tubules into smaller tubules and vesicles. Within vesicles produced by an in vitro budding reaction, GMx33 remains segregated in a matrixlike tail region that sometimes contains Golgin-245. This trans-matrix often links a few vesicles together. Together these data suggest that GMx33 is a member of the trans-Golgi matrix and offer clues regarding the role of the trans-Golgi matrix in sorting and exit from the Golgi.
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Affiliation(s)
- Christopher M Snyder
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA
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