51
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Cervigni RI, Bonavita R, Barretta ML, Spano D, Ayala I, Nakamura N, Corda D, Colanzi A. JNK2 controls fragmentation of the Golgi complex and the G2/M transition through phosphorylation of GRASP65. J Cell Sci 2015; 128:2249-60. [PMID: 25948586 DOI: 10.1242/jcs.164871] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 04/20/2015] [Indexed: 11/20/2022] Open
Abstract
In mammalian cells, the Golgi complex is composed of stacks that are connected by membranous tubules. During G2, the Golgi complex is disassembled into isolated stacks. This process is required for entry into mitosis, indicating that the correct inheritance of the organelle is monitored by a 'Golgi mitotic checkpoint'. However, the regulation and the molecular mechanisms underlying this Golgi disassembly are still poorly understood. Here, we show that JNK2 has a crucial role in the G2-specific separation of the Golgi stacks through phosphorylation of Ser277 of the Golgi-stacking protein GRASP65 (also known as GORASP1). Inhibition of JNK2 by RNA interference or by treatment with three unrelated JNK inhibitors causes a potent and persistent cell cycle block in G2. JNK activity becomes dispensable for mitotic entry if the Golgi complex is disassembled by brefeldin A treatment or by GRASP65 depletion. Finally, measurement of the Golgi fluorescence recovery after photobleaching demonstrates that JNK is required for the cleavage of the tubules connecting Golgi stacks. Our findings reveal that a JNK2-GRASP65 signalling axis has a crucial role in coupling Golgi inheritance and G2/M transition.
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Affiliation(s)
- Romina Ines Cervigni
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, Naples 80131, Italy
| | - Raffaella Bonavita
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, Naples 80131, Italy
| | - Maria Luisa Barretta
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, Naples 80131, Italy
| | - Daniela Spano
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, Naples 80131, Italy
| | - Inmaculada Ayala
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, Naples 80131, Italy
| | - Nobuhiro Nakamura
- Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita, Kyoto 603-8555, Japan
| | - Daniela Corda
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, Naples 80131, Italy
| | - Antonino Colanzi
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, Naples 80131, Italy
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52
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Stein MF, Blume K, Heilingloh CS, Kummer M, Biesinger B, Sticht H, Steinkasserer A. CD83 and GRASP55 interact in human dendritic cells. Biochem Biophys Res Commun 2015; 459:42-8. [PMID: 25701785 DOI: 10.1016/j.bbrc.2015.02.057] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 02/11/2015] [Indexed: 11/23/2022]
Abstract
CD83 is one of the best known surface markers for mature human dendritic cells (DCs). The full-length 45 kDa type-I membrane-bound form (mbCD83) is strongly glycosylated upon DCs maturation. As co-stimulatory properties of CD83 are attributed to mbCD83 surface expression is required for efficient T-cell stimulation by mature DCs. By yeast two-hybrid screening, we were able to identify GRASP55 as interaction partner of CD83. DCs maturation induces endogenous CD83 protein expression with simultaneous regulation of CD83 glycosylation, interaction and co-localization with GRASP55 and CD83 surface exposure. GRASP55 is especially known for its role in maintaining Golgi architecture, but also plays a role in Golgi transport of specific cargo proteins bearing a C-terminal valine residue. Here we additionally demonstrate that binding of CD83 and GRASP55 rely on the C-terminal TELV-motif of CD83. Mutation of this TELV-motif not only disrupted binding to GRASP55, but also altered the glycosylation pattern of CD83 and reduced its membrane expression. Here we show for the first time that GRASP55 interacts with CD83 shortly after induction of DC maturation and that this interaction plays a role in CD83 glycosylation as well as in surface expression of CD83 on DCs.
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Affiliation(s)
- Marcello F Stein
- Department of Immune Modulation, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Katja Blume
- Department of Immune Modulation, Universitätsklinikum Erlangen, Erlangen, Germany
| | | | - Mirko Kummer
- Department of Immune Modulation, Universitätsklinikum Erlangen, Erlangen, Germany
| | | | - Heinrich Sticht
- Department of Biochemistry, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
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53
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Ito Y, Uemura T, Nakano A. Formation and maintenance of the Golgi apparatus in plant cells. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 310:221-87. [PMID: 24725428 DOI: 10.1016/b978-0-12-800180-6.00006-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The Golgi apparatus plays essential roles in intracellular trafficking, protein and lipid modification, and polysaccharide synthesis in eukaryotic cells. It is well known for its unique stacked structure, which is conserved among most eukaryotes. However, the mechanisms of biogenesis and maintenance of the structure, which are deeply related to ER-Golgi and intra-Golgi transport systems, have long been mysterious. Now having extremely powerful microscopic technologies developed for live-cell imaging, the plant Golgi apparatus provides an ideal system to resolve the question. The plant Golgi apparatus has unique features that are not conserved in other kingdoms, which will also give new insights into the Golgi functions in plant life. In this review, we will summarize the features of the plant Golgi apparatus and transport mechanisms around it, with a focus on recent advances in Golgi biogenesis by live imaging of plants cells.
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Affiliation(s)
- Yoko Ito
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Tomohiro Uemura
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Akihiko Nakano
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo, Japan; Live Cell Molecular Imaging Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama, Japan.
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54
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Vasiliev JM, Samoylov VI. Regulatory functions of microtubules. BIOCHEMISTRY (MOSCOW) 2014; 78:37-40. [PMID: 23379557 DOI: 10.1134/s0006297913010045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This mini-review summarizes literature and original data about the role of microtubules in interphase animal cells. Recent data have shown that functioning of microtubules is essential for such diverse phenomena as directional cell movements, distribution of organelles in the cytoplasm, and neuronal memory in the central nervous system. It is suggested that microtubules can act as an important regulatory system in eukaryotic cells. Possible mechanisms of these functions are discussed.
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Affiliation(s)
- J M Vasiliev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
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55
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Lavieu G, Dunlop MH, Lerich A, Zheng H, Bottanelli F, Rothman JE. The Golgi ribbon structure facilitates anterograde transport of large cargoes. Mol Biol Cell 2014; 25:3028-36. [PMID: 25103235 PMCID: PMC4230591 DOI: 10.1091/mbc.e14-04-0931] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Breaking down the ribbon of mammalian cells strongly inhibits intra-Golgi transport of large cargoes without altering the rate of transport of smaller cargoes. These results imply that the ribbon structure is an essential requirement for transport of large cargoes in mammalian cells. In mammalian cells, individual Golgi stacks fuse laterally to form the characteristic perinuclear ribbon structure. Yet the purpose of this remarkable structure has been an enigma. We report that breaking down the ribbon of mammalian cells strongly inhibits intra-Golgi transport of large cargoes without altering the rate of transport of smaller cargoes. In addition, insect cells that naturally harbor dispersed Golgi stacks have limited capacity to transport artificial oversized cargoes. These results imply that the ribbon structure is an essential requirement for transport of large cargoes in mammalian cells, and we suggest that this is because it enables the dilated rims of cisternae (containing the aggregates) to move across the stack as they transfer among adjacent stacks within the ribbon structure.
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Affiliation(s)
- Gregory Lavieu
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520
| | - Myun Hwa Dunlop
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520
| | - Alexander Lerich
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520
| | - Hong Zheng
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520
| | - Francesca Bottanelli
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520
| | - James E Rothman
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520
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56
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Veenendaal T, Jarvela T, Grieve AG, van Es JH, Linstedt AD, Rabouille C. GRASP65 controls the cis Golgi integrity in vivo. Biol Open 2014; 3:431-43. [PMID: 24795147 PMCID: PMC4058077 DOI: 10.1242/bio.20147757] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
GRASP65 and GRASP55 are peripheral Golgi proteins localized to cis and medial/trans cisternae, respectively. They are implicated in diverse aspects of protein transport and structure related to the Golgi complex, including the stacking of the Golgi stack and/or the linking of mammalian Golgi stacks into the Golgi ribbon. Using a mouse model, we interfered with GRASP65 by homologous recombination and confirmed its absence of expression. Surprisingly, the mice were healthy and fertile with no apparent defects in tissue, cellular or subcellular organization. Immortalized MEFs derived from the mice did not show any growth or morphological defects. However, despite the normal appearance of the Golgi ribbon, a fluorescence recovery after photobleaching assay revealed functional discontinuities specific to the cis cisternal membrane network. This leads to a strong change in the plasma membrane GSII lectin staining that was also observed in certain mutant tissues. These findings substantiate the role of GRASP65 in continuity of the cis Golgi network required for proper glycosylation, while showing that neither this continuity nor GRASP65 itself are essential for the viability of a complex organism.
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Affiliation(s)
- Tineke Veenendaal
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Tim Jarvela
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Adam G Grieve
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands Present address: Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Johan H van Es
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Adam D Linstedt
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Catherine Rabouille
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands Department of Cell Biology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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57
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Ferraro F, Kriston-Vizi J, Metcalf DJ, Martin-Martin B, Freeman J, Burden JJ, Westmoreland D, Dyer CE, Knight AE, Ketteler R, Cutler DF. A two-tier Golgi-based control of organelle size underpins the functional plasticity of endothelial cells. Dev Cell 2014; 29:292-304. [PMID: 24794632 PMCID: PMC4022834 DOI: 10.1016/j.devcel.2014.03.021] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 02/03/2014] [Accepted: 03/27/2014] [Indexed: 01/10/2023]
Abstract
Weibel-Palade bodies (WPBs), endothelial-specific secretory granules that are central to primary hemostasis and inflammation, occur in dimensions ranging between 0.5 and 5 μm. How their size is determined and whether it has a functional relevance are at present unknown. Here, we provide evidence for a dual role of the Golgi apparatus in controlling the size of these secretory carriers. At the ministack level, cisternae constrain the size of nanostructures (“quanta”) of von Willebrand factor (vWF), the main WPB cargo. The ribbon architecture of the Golgi then allows copackaging of a variable number of vWF quanta within the continuous lumen of the trans-Golgi network, thereby generating organelles of different sizes. Reducing the WPB size abates endothelial cell hemostatic function by drastically diminishing platelet recruitment, but, strikingly, the inflammatory response (the endothelial capacity to engage leukocytes) is unaltered. Size can thus confer functional plasticity to an organelle by differentially affecting its activities. Cisternal length within Golgi ministacks controls the size of vWF cargo nanostructures The Golgi ribbon allows copackaging of vWF nanostructures into WPBs of variable size Endothelial cells with small WPBs display a reduced platelet recruitment capability Control of organelle size may confer hemostatic plasticity to endothelia
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Affiliation(s)
- Francesco Ferraro
- Endothelial Cell Biology Laboratory, Laboratory for Molecular and Cellular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Janos Kriston-Vizi
- Translational Research Resource Center, Laboratory for Molecular and Cellular Biology, University College London, Gower Street, London WC1E 6BT, UK; Bioinformatics Image Core, Laboratory for Molecular and Cellular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Daniel J Metcalf
- Analytical Science Division, National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, UK
| | - Belen Martin-Martin
- Endothelial Cell Biology Laboratory, Laboratory for Molecular and Cellular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Jamie Freeman
- Translational Research Resource Center, Laboratory for Molecular and Cellular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Jemima J Burden
- Electron Microscopy Laboratory, Laboratory for Molecular and Cellular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - David Westmoreland
- Endothelial Cell Biology Laboratory, Laboratory for Molecular and Cellular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Clare E Dyer
- Endothelial Cell Biology Laboratory, Laboratory for Molecular and Cellular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Alex E Knight
- Analytical Science Division, National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, UK
| | - Robin Ketteler
- Translational Research Resource Center, Laboratory for Molecular and Cellular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Daniel F Cutler
- Endothelial Cell Biology Laboratory, Laboratory for Molecular and Cellular Biology, University College London, Gower Street, London WC1E 6BT, UK.
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58
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Watanabe T, Bochimoto H, Koga D, Hosaka M, Ushiki T. Functional implications of the Golgi and microtubular network in gonadotropes. Mol Cell Endocrinol 2014; 385:88-96. [PMID: 24121198 DOI: 10.1016/j.mce.2013.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 09/30/2013] [Accepted: 10/01/2013] [Indexed: 02/01/2023]
Abstract
In contrast to the widely accepted images of the Golgi apparatus as a cup-like shape, the Golgi in pituitary gonadotropes is organized as a spherical shape in which the outer and inner faces are cis- and trans-Golgi elements, respectively. At the center of the spherical Golgi, a pair of centrioles is situated as a microtubule-organizing center from which radiating microtubules isotropically extend toward the cell periphery. This review focuses on the significance of the characteristic organization of the Golgi and microtubule network in gonadotropes, considering the roles of microtubule-dependent membrane transport in the formation and maintenance of the Golgi structure. Because the highly symmetrical organization of the Golgi is possibly perturbed in response to experimental treatments of gonadotropes, monitoring of the Golgi structure in gonadotropes under various experimental conditions will be a novel in vivo approach to elucidate the biogenesis of the Golgi apparatus.
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Affiliation(s)
- Tsuyoshi Watanabe
- Department of Microscopic Anatomy and Cell Biology, Asahikawa Medical University, Asahikawa, Japan.
| | - Hiroki Bochimoto
- Department of Microscopic Anatomy and Cell Biology, Asahikawa Medical University, Asahikawa, Japan
| | - Daisuke Koga
- Division of Microscopic Anatomy and Bio-imaging, Department of Cellular Function, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Masahiro Hosaka
- Laboratory of Molecular Life Sciences, Department of Biotechnology, Akita Prefectural University, Akita, Japan
| | - Tatsuo Ushiki
- Division of Microscopic Anatomy and Bio-imaging, Department of Cellular Function, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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59
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Ji G, Ji H, Mo X, Li T, Yu Y, Hu Z. The role of GRASPs in morphological alterations of Golgi apparatus: mechanisms and effects. Rev Neurosci 2014; 24:485-97. [PMID: 24002661 DOI: 10.1515/revneuro-2013-0020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 08/10/2013] [Indexed: 11/15/2022]
Abstract
The Golgi apparatus (GA) is a pivotal organelle in cell metabolism, functioning not only in the processing and transportation of cargoes but also in ion homeostasis, cell apoptosis, and stress sensing. We are interested in the intricate role of GA and the recently present novel concept of 'GA stress'. GA shows various morphological alterations in many neurodegenerative diseases and cell apoptosis induced by biochemical reagents, mechanisms in which oxidative stress is strongly involved. In turn, the structural changes and morphological alterations of the GA could also transduce stress signals. Therefore, besides the biochemical changes, more attention should be paid to the morphological alterations of the GA itself during pathological processes and diseases. The Golgi reassembly and stacking proteins (GRASPs) have been identified as important components acting in the transformation of Golgi structure, and they may thus affect the Golgi functions and cell behavior. In this review, we will discuss the intricate role of the GRASPs in remodeling the GA morphology and focus on their mechanisms and effects in the processes of Golgi stacking, mitosis, cell apoptosis, and cargo secretion. We would also like to provide a further prospective of their potential biological values in neurodegenerative diseases.
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60
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Heinrich F, Nanda H, Goh HZ, Bachert C, Lösche M, Linstedt AD. Myristoylation restricts orientation of the GRASP domain on membranes and promotes membrane tethering. J Biol Chem 2014; 289:9683-91. [PMID: 24505136 DOI: 10.1074/jbc.m113.543561] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mammalian Golgi reassembly stacking protein (GRASP) proteins are Golgi-localized homotypic membrane tethers that organize Golgi stacks into a long, contiguous ribbon-like structure. It is unknown how GRASPs undergo trans pairing given that cis interactions between the proteins in the plane of the membrane are intrinsically favored. To test the hypothesis that myristoylation of the self-interacting GRASP domain restricts its orientation on the membrane to favor trans pairing, we established an in vitro assay that recapitulates GRASP-dependent membrane tethering and used neutron reflection under similar conditions to determine the orientation of the GRASP domain. In vivo, the membrane association of GRASP proteins is conferred by the simultaneous insertion of an N-terminal myristic acid and binding to a Golgi-associated binding partner. In our assay, the latter contact was replaced using a C-terminal hexa-His moiety, which bound to Ni(2+)-conjugated lipids incorporated into a substrate-supported bilayer lipid membrane. Nonmyristoylated protein lacked a fixed orientation on the membrane and inefficiently tethered liposomes. In contrast, myristoylated GRASP promoted tethering and exhibited a unique membrane complex. Thus, myristoylation restricts the membrane orientation of the GRASP domain favoring interactions in trans for membrane tethering.
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61
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Dong Z, Zuber C, Pierce M, Stanley P, Roth J. Reduction in Golgi apparatus dimension in the absence of a residential protein, N-acetylglucosaminyltransferase V. Histochem Cell Biol 2014; 141:153-64. [PMID: 24078077 PMCID: PMC4085668 DOI: 10.1007/s00418-013-1146-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2013] [Indexed: 11/28/2022]
Abstract
Various proteins are involved in the generation and maintenance of the membrane complex known as the Golgi apparatus. We have used mutant Chinese hamster ovary (CHO) cell lines Lec4 and Lec4A lacking N-acetylglucosaminyltransferase V (GlcNAcT-V, MGAT5) activity and protein in the Golgi apparatus to study the effects of the absence of a single glycosyltransferase on the Golgi apparatus dimension. Quantification of immunofluorescence in serial confocal sections for Golgi α-mannosidase II and electron microscopic morphometry revealed a reduction in Golgi volume density up to 49 % in CHO Lec4 and CHO Lec4A cells compared to parental CHO cells. This reduction in Golgi volume density could be reversed by stable transfection of Lec4 cells with a cDNA encoding Mgat5. Inhibition of the synthesis of β1,6-branched N-glycans by swainsonine had no effect on Golgi volume density. In addition, no effect on Golgi volume density was observed in CHO Lec1 cells that contain enzymatically active GlcNAcT-V, but cannot synthesize β1,6-branched glycans due to an inactive GlcNAcT-I in their Golgi apparatus. These results indicate that it may be the absence of the GlcNAcT-V protein that is the determining factor in reducing Golgi volume density. No dimensional differences existed in cross-sectioned cisternal stacks between Lec4 and control CHO cells, but significantly reduced Golgi stack hits were observed in cross-sectioned Lec4 cells. Therefore, the Golgi apparatus dimensional change in Lec4 and Lec4A cells may be due to a compaction of the organelle.
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Affiliation(s)
- Zhizhong Dong
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zürich, 8091 Zürich, Switzerland
| | - Christian Zuber
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zürich, 8091 Zürich, Switzerland
| | - Michael Pierce
- Complex Carbohydrate Research Center, Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Pamela Stanley
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Jürgen Roth
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zürich, 8091 Zürich, Switzerland
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62
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Abstract
Two classes of proteins that bind to each other and to Golgi membranes have been implicated in the adhesion of Golgi cisternae to each other to form their characteristic stacks: Golgi reassembly and stacking proteins 55 and 65 (GRASP55 and GRASP65) and Golgin of 45 kDa and Golgi matrix protein of 130 kDa. We report here that efficient stacking occurs in the absence of GRASP65/55 when either Golgin is overexpressed, as judged by quantitative electron microscopy. The Golgi stacks in these GRASP-deficient HeLa cells were normal both in morphology and in anterograde cargo transport. This suggests the simple hypothesis that the total amount of adhesive energy gluing cisternae dictates Golgi cisternal stacking, irrespective of which molecules mediate the adhesive process. In support of this hypothesis, we show that adding artificial adhesive energy between cisternae and mitochondria by dimerizing rapamycin-binding domain and FK506-binding protein domains that are attached to cisternal adhesive proteins allows mitochondria to invade the stack and even replace Golgi cisternae within a few hours. These results indicate that although Golgi stacking is a highly complicated process involving a large number of adhesive and regulatory proteins, the overriding principle of a Golgi stack assembly is likely to be quite simple. From this simplified perspective, we propose a model, based on cisternal adhesion and cisternal maturation as the two core principles, illustrating how the most ancient form of Golgi stacking might have occurred using only weak cisternal adhesive processes because of the differential between the rate of influx and outflux of membrane transport through the Golgi.
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63
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Jarvela T, Linstedt AD. Isoform-specific tethering links the Golgi ribbon to maintain compartmentalization. Mol Biol Cell 2013; 25:133-44. [PMID: 24227884 PMCID: PMC3873884 DOI: 10.1091/mbc.e13-07-0395] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Use of photoinactivation, cisternae-specific fluorescence recovery, and high-resolution microscopy shows that the membrane tethers GRASP65 and GRASP55 on early and late Golgi membranes, respectively, are critical to the specific, homotypic fusion of the membranes on which they reside. Homotypic membrane tethering by the Golgi reassembly and stacking proteins (GRASPs) is required for the lateral linkage of mammalian Golgi ministacks into a ribbon-like membrane network. Although GRASP65 and GRASP55 are specifically localized to cis and medial/trans cisternae, respectively, it is unknown whether each GRASP mediates cisternae-specific tethering and whether such specificity is necessary for Golgi compartmentalization. Here each GRASP was tagged with KillerRed (KR), expressed in HeLa cells, and inhibited by 1-min exposure to light. Significantly, inactivation of either GRASP unlinked the Golgi ribbon, and the immediate effect of GRASP65-KR inactivation was a loss of cis- rather than trans-Golgi integrity, whereas inactivation of GRASP55-KR first affected the trans- and not the cis-Golgi. Thus each GRASP appears to play a direct and cisternae-specific role in linking ministacks into a continuous membrane network. To test the consequence of loss of cisternae-specific tethering, we generated Golgi membranes with a single GRASP on all cisternae. Remarkably, the membranes exhibited the full connectivity of wild-type Golgi ribbons but were decompartmentalized and defective in glycan processing. Thus the GRASP isoforms specifically link analogous cisternae to ensure Golgi compartmentalization and proper processing.
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Affiliation(s)
- Timothy Jarvela
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213
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64
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Feng Y, Yu W, Li X, Lin S, Zhou Y, Hu J, Liu X. Structural insight into Golgi membrane stacking by GRASP65 and GRASP55 proteins. J Biol Chem 2013; 288:28418-27. [PMID: 23940043 DOI: 10.1074/jbc.m113.478024] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The stacking of Golgi cisternae involves GRASP65 and GRASP55. The oligomerization of the N-terminal GRASP domain of these proteins, which consists of two tandem PDZ domains, is required to tether the Golgi membranes. However, the molecular basis for GRASP assembly is unclear. Here, we determined the crystal structures of the GRASP domain of GRASP65 and GRASP55. The structures reveal similar homotypic interactions: the GRASP domain forms a dimer in which the peptide-binding pockets of the two neighboring PDZ2 domains face each other, and the dimers are further connected by the C-terminal tail of one GRASP domain inserting into the binding pocket of the PDZ1 domain in another dimer. Biochemical analysis suggests that both types of contacts are relatively weak but are needed in combination for GRASP-mediated Golgi stacking. Our results unveil a novel mode of membrane tethering by GRASP proteins and provide insight into the mechanism of Golgi stacking.
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Affiliation(s)
- Yanbin Feng
- From the Department of Biochemistry and Molecular Biology, College of Life Sciences, and State Key Laboratory of Medicinal Chemical Biology and
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65
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Tang D, Wang Y. Cell cycle regulation of Golgi membrane dynamics. Trends Cell Biol 2013; 23:296-304. [PMID: 23453991 DOI: 10.1016/j.tcb.2013.01.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 01/21/2013] [Accepted: 01/30/2013] [Indexed: 01/12/2023]
Abstract
The Golgi apparatus is a membranous organelle in the cell that plays essential roles in protein and lipid trafficking, sorting, processing, and modification. Its basic structure is a stack of closely aligned flattened cisternae. In mammalian cells, dozens of Golgi stacks are often laterally linked into a ribbon-like structure. Biogenesis of the Golgi during cell division occurs through a sophisticated disassembly and reassembly process that can be divided into three distinct but cooperative steps, including the deformation and reformation of the Golgi cisternae, stacks, and ribbon. Here, we review our current understanding of the protein machineries that control these three steps in the cycle of mammalian cell division: GRASP65 and GRASP55 in Golgi stack and ribbon formation; ubiquitin and AAA ATPases in postmitotic Golgi membrane fusion; and golgins and cytoskeleton in Golgi ribbon formation.
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Affiliation(s)
- Danming Tang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109-1048, USA
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66
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Romero N, Dumur CI, Martinez H, García IA, Monetta P, Slavin I, Sampieri L, Koritschoner N, Mironov AA, De Matteis MA, Alvarez C. Rab1b overexpression modifies Golgi size and gene expression in HeLa cells and modulates the thyrotrophin response in thyroid cells in culture. Mol Biol Cell 2013; 24:617-32. [PMID: 23325787 PMCID: PMC3583665 DOI: 10.1091/mbc.e12-07-0530] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
An increase in Rab1b levels induces changes in Golgi size and in gene expression. These Rab1b-dependent changes require the activity of p38 mitogen-activated protein kinase and the cAMP-responsive element binding protein consensus binding. The results show a Rab1b increase in secretory cells after stimulation and suggest that this increase is required to elicit a secretory response. Rab1b belongs to the Rab-GTPase family that regulates membrane trafficking and signal transduction systems able to control diverse cellular activities, including gene expression. Rab1b is essential for endoplasmic reticulum–Golgi transport. Although it is ubiquitously expressed, its mRNA levels vary among different tissues. This work aims to characterize the role of the high Rab1b levels detected in some secretory tissues. We report that, in HeLa cells, an increase in Rab1b levels induces changes in Golgi size and gene expression. Significantly, analyses applied to selected genes, KDELR3, GM130 (involved in membrane transport), and the proto-oncogene JUN, indicate that the Rab1b increase acts as a molecular switch to control the expression of these genes at the transcriptional level, resulting in changes at the protein level. These Rab1b-dependent changes require the activity of p38 mitogen-activated protein kinase and the cAMP-responsive element-binding protein consensus binding site in those target promoter regions. Moreover, our results reveal that, in a secretory thyroid cell line (FRTL5), Rab1b expression increases in response to thyroid-stimulating hormone (TSH). Additionally, changes in Rab1b expression in FRTL5 cells modify the specific TSH response. Our results show, for the first time, that changes in Rab1b levels modulate gene transcription and strongly suggest that a Rab1b increase is required to elicit a secretory response.
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Affiliation(s)
- Nahuel Romero
- Centro de Investigaciones en Bioquímica Clínica e Inmunología, Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba 5000, Argentina
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67
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Abstract
The Golgi complex of mammalian cells is composed of interconnected stacks of flattened cisternae that form a continuous membrane system in the pericentriolar region of the cell. At the onset of mitosis, this so-called Golgi ribbon is converted into small tubular-vesicular clusters in a tightly regulated fragmentation process, which leads to a temporary loss of the physical Golgi-centrosome proximity. Mitotic Golgi breakdown is required for Golgi partitioning into the two daughter cells, cell cycle progression and may contribute to the dispersal of Golgi-associated signaling molecules. Here, we review our current understanding of the mechanisms that control mitotic Golgi reorganization, its biological significance, and assays that are used to study this process.
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68
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Xiang Y, Zhang X, Nix DB, Katoh T, Aoki K, Tiemeyer M, Wang Y. Regulation of protein glycosylation and sorting by the Golgi matrix proteins GRASP55/65. Nat Commun 2013; 4:1659. [PMID: 23552074 PMCID: PMC3620728 DOI: 10.1038/ncomms2669] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 02/27/2013] [Indexed: 12/27/2022] Open
Abstract
The Golgi receives the entire output of newly synthesized cargo from the endoplasmic reticulum, processes it in the stack largely through modification of bound oligosaccharides, and sorts it in the trans-Golgi network. GRASP65 and GRASP55, two proteins localized to the Golgi stack and early secretory pathway, mediate processes including Golgi stacking, Golgi ribbon linking and unconventional secretion. Previously, we have shown that GRASP depletion in cells disrupts Golgi stack formation. Here we report that knockdown of the GRASP proteins, alone or combined, accelerates protein trafficking through the Golgi membranes but also has striking negative effects on protein glycosylation and sorting. These effects are not caused by Golgi ribbon unlinking, unconventional secretion or endoplasmic reticulum stress. We propose that GRASP55/65 are negative regulators of exocytic transport and that this slowdown helps to ensure more complete protein glycosylation in the Golgi stack and proper sorting at the trans-Golgi network.
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Affiliation(s)
- Yi Xiang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109-1048, USA
| | - Xiaoyan Zhang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109-1048, USA
| | - David B. Nix
- The Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602-4712, USA
- The Department of Biochemistry and Molecular Biology, B122 Life Sciences Building, University of Georgia, Athens, GA 30602-5016, USA
| | - Toshihiko Katoh
- The Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602-4712, USA
| | - Kazuhiro Aoki
- The Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602-4712, USA
| | - Michael Tiemeyer
- The Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602-4712, USA
- The Department of Biochemistry and Molecular Biology, B122 Life Sciences Building, University of Georgia, Athens, GA 30602-5016, USA
| | - Yanzhuang Wang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109-1048, USA
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69
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MEK1 inactivates Myt1 to regulate Golgi membrane fragmentation and mitotic entry in mammalian cells. EMBO J 2012; 32:72-85. [PMID: 23241949 DOI: 10.1038/emboj.2012.329] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 11/16/2012] [Indexed: 11/08/2022] Open
Abstract
The pericentriolar stacks of Golgi cisternae are separated from each other in G2 and fragmented extensively during mitosis. MEK1 is required for Golgi fragmentation in G2 and for the entry of cells into mitosis. We now report that Myt1 mediates MEK1's effects on the Golgi complex. Knockdown of Myt1 by siRNA increased the efficiency of Golgi complex fragmentation by mitotic cytosol in permeabilized and intact HeLa cells. Myt1 knockdown eliminated the requirement of MEK1 in Golgi fragmentation and alleviated the delay in mitotic entry due to MEK1 inhibition. The phosphorylation of Myt1 by MEK1 requires another kinase but is independent of RSK, Plk, and CDK1. Altogether our findings reveal that Myt1 is inactivated by MEK1 mediated phosphorylation to fragment the Golgi complex in G2 and for the entry of cells into mitosis. It is known that Myt1 inactivation is required for CDK1 activation. Myt1 therefore is an important link by which MEK1 dependent fragmentation of the Golgi complex in G2 is connected to the CDK1 mediated breakdown of Golgi into tubules and vesicles in mitosis.
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70
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Kienzle C, Eisler SA, Villeneuve J, Brummer T, Olayioye MA, Hausser A. PKD controls mitotic Golgi complex fragmentation through a Raf-MEK1 pathway. Mol Biol Cell 2012; 24:222-33. [PMID: 23242995 PMCID: PMC3564543 DOI: 10.1091/mbc.e12-03-0198] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Before entering mitosis, the stacks of the Golgi cisternae are separated from each other, and inhibiting this process delays entry of mammalian cells into mitosis. Protein kinase D (PKD) is known to be involved in Golgi-to-cell surface transport by controlling the biogenesis of specific transport carriers. Here we show that depletion of PKD1 and PKD2 proteins from HeLa cells by small interfering RNA leads to the accumulation of cells in the G2 phase of the cell cycle and prevents cells from entering mitosis. We further provide evidence that inhibition of PKD blocks mitotic Raf-1 and mitogen-activated protein kinase kinase (MEK) activation, and, as a consequence, mitotic Golgi fragmentation, which could be rescued by expression of active MEK1. Finally, Golgi fluorescence recovery after photobleaching analyses demonstrate that PKD is crucial for the cleavage of the noncompact zones of Golgi membranes in G2 phase. Our findings suggest that PKD controls interstack Golgi connections in a Raf-1/MEK1-dependent manner, a process required for entry of the cells into mitosis.
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Affiliation(s)
- Christine Kienzle
- Institute of Cell Biology and Immunology, University of Stuttgart, 70569 Stuttgart, Germany
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71
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Abstract
Golgins are a family of long rod-like proteins characterized by the presence of central coiled-coil domains. Members of the golgin family have important roles in membrane trafficking, where they function as tethering factors that capture transport vesicles and facilitate membrane fusion. Golgin family members also have essential roles in maintaining the organization of the Golgi apparatus. Knockdown of individual golgins in cultured cells resulted in the disruption of the Golgi structure and the dispersal of Golgi marker proteins throughout the cytoplasm. However, these cellular phenotypes have not always been recapitulated in vivo. For example, embryonic development proceeds much further than expected and Golgi disruption was observed in only a subset of cell types in mice lacking the ubiquitously expressed golgin GMAP-210. Cell-type specific functional compensation among golgins may explain the absence of global cell lethality when a ubiquitously expressed golgin is missing. In this study we show that functional compensation does not occur for the golgin USO1. Mice lacking this ubiquitously expressed protein exhibit disruption of Golgi structure and early embryonic lethality, indicating that USO1 is indispensable for early embryonic development.
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Affiliation(s)
- Susie Kim
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, Massachusetts, United States of America
| | - Adele Hill
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, Massachusetts, United States of America
| | - Matthew L. Warman
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, Massachusetts, United States of America
- Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts, United States of America
| | - Patrick Smits
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, Massachusetts, United States of America
- * E-mail: Patrick Smits
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72
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Cancino J, Luini A. Signaling Circuits on the Golgi Complex. Traffic 2012; 14:121-34. [DOI: 10.1111/tra.12022] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 10/12/2012] [Accepted: 10/12/2012] [Indexed: 01/21/2023]
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73
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Yadav S, Puthenveedu MA, Linstedt AD. Golgin160 recruits the dynein motor to position the Golgi apparatus. Dev Cell 2012; 23:153-65. [PMID: 22814606 DOI: 10.1016/j.devcel.2012.05.023] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 04/19/2012] [Accepted: 05/29/2012] [Indexed: 11/26/2022]
Abstract
Membrane motility is a fundamental characteristic of all eukaryotic cells. One of the best-known examples is that of the mammalian Golgi apparatus, where constant inward movement of Golgi membranes results in its characteristic position near the centrosome. While it is clear that the minus-end-directed motor dynein is required for this process, the mechanism and regulation of dynein recruitment to Golgi membranes remains unknown. Here, we show that the Golgi protein golgin160 recruits dynein to Golgi membranes. This recruitment confers centripetal motility to membranes and is regulated by the GTPase Arf1. Further, during cell division, motor association with membranes is regulated by the dissociation of the receptor-motor complex from membranes. These results identify a cell-cycle-regulated membrane receptor for a molecular motor and suggest a mechanistic basis for achieving the dramatic changes in organelle positioning seen during cell division.
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Affiliation(s)
- Smita Yadav
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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74
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Tang D, Yuan H, Vielemeyer O, Perez F, Wang Y. Sequential phosphorylation of GRASP65 during mitotic Golgi disassembly. Biol Open 2012; 1:1204-14. [PMID: 23259055 PMCID: PMC3522882 DOI: 10.1242/bio.20122659] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 09/04/2012] [Indexed: 01/30/2023] Open
Abstract
GRASP65 phosphorylation during mitosis and dephosphorylation after mitosis are required for Golgi disassembly and reassembly during the cell cycle. At least eight phosphorylation sites on GRASP65 have been identified, but whether they are modified in a coordinated fashion during mitosis is so far unknown. In this study, we raised phospho-specific antibodies that recognize phosphorylated T220/T224, S277 and S376 residues of GRASP65, respectively. Biochemical analysis showed that cdc2 phosphorylates all three sites, while plk1 enhances the phosphorylation. Microscopic studies using these antibodies for double and triple labeling demonstrate sequential phosphorylation and dephosphorylation during the cell cycle. S277 and S376 are phosphorylated from late G2 phase through metaphase until telophase when the new Golgi is reassembled. T220/224 is not modified until prophase, but is highly modified from prometaphase to anaphase. In metaphase, phospho-T220/224 signal localizes on both Golgi haze and mitotic Golgi clusters that represent dispersed Golgi vesicles and Golgi remnants, respectively, while phospho-S277 and S376 labeling is more concentrated on mitotic Golgi clusters. Expression of a phosphorylation-resistant GRASP65 mutant T220A/T224A inhibited mitotic Golgi fragmentation to a much larger extent than the expression of the S277A and S376A mutants. In cytokinesis, T220/224 dephosphorylation occurs prior to that of S277, but after S376. This study provides evidence that GRASP65 is sequentially phosphorylated and dephosphorylated during mitosis at different sites to orchestrate Golgi disassembly and reassembly during cell division, with phosphorylation of the T220/224 site being most critical in the process.
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Affiliation(s)
- Danming Tang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan , 830 North University Avenue, Ann Arbor, MI 48109-1048 , USA
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75
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Kirkbride KC, Hong NH, French CL, Clark ES, Jerome WG, Weaver AM. Regulation of late endosomal/lysosomal maturation and trafficking by cortactin affects Golgi morphology. Cytoskeleton (Hoboken) 2012; 69:625-43. [PMID: 22991200 PMCID: PMC3746372 DOI: 10.1002/cm.21051] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 07/11/2012] [Accepted: 07/11/2012] [Indexed: 01/23/2023]
Abstract
Cortactin is a branched actin regulator and tumor-overexpressed protein that promotes vesicular trafficking at a variety of cellular sites, including endosomes and the trans-Golgi network. To better understand its role in secretory trafficking, we investigated its function in Golgi homeostasis. Here, we report that knockdown (KD) of cortactin leads to a dramatic change in Golgi morphology by light microscopy, dependent on binding the Arp2/3 actin-nucleating complex. Surprisingly, there was little effect of cortactin-KD on anterograde trafficking of the constitutive cargo vesicular stomatitis virus glycoprotein (VSVG), Golgi assembly from endoplasmic reticulum membranes upon Brefeldin A washout, or Golgi ultrastructure. Instead, electron microscopy studies revealed that cortactin-KD cells contained a large number of immature-appearing late endosomal/lysosomal (LE/Lys) hybrid organelles, similar to those found in lysosomal storage diseases. Consistent with a defect in LE/Lys trafficking, cortactin-KD cells also exhibited accumulation of free cholesterol and retention of the retrograde Golgi cargo mannose-6-phosphate receptor in LE. Inhibition of LE maturation by treatment of control cells with Rab7 siRNA or chloroquine led to a compact Golgi morphology similar to that observed in cortactin-KD cells. Furthermore, the Golgi morphology defects of cortactin-KD cells could be rescued by removal of cholesterol-containing lipids from the media, suggesting that buildup of cholesterol-rich membranes in immature LE/Lys induced disturbances in retrograde trafficking. Taken together, these data reveal that LE/Lys maturation and trafficking are highly sensitive to cortactin-regulated branched actin assembly and suggests that cytoskeletal-induced Golgi morphology changes can be a consequence of altered trafficking at late endosomes.
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Affiliation(s)
- Kellye C Kirkbride
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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76
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Chua CEL, Lim YS, Lee MG, Tang BL. Non-classical membrane trafficking processes galore. J Cell Physiol 2012; 227:3722-30. [DOI: 10.1002/jcp.24082] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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77
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Corda D, Barretta ML, Cervigni RI, Colanzi A. Golgi complex fragmentation in G2/M transition: An organelle-based cell-cycle checkpoint. IUBMB Life 2012; 64:661-70. [PMID: 22730233 DOI: 10.1002/iub.1054] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 04/29/2012] [Indexed: 11/06/2022]
Abstract
In mammalian cells, the Golgi complex is organized into a continuous membranous system known as the Golgi ribbon, which is formed by individual Golgi stacks that are laterally connected by tubular bridges. During mitosis, the Golgi ribbon undergoes extensive fragmentation through a multistage process that is required for its correct partitioning into the daughter cells. Importantly, inhibition of this Golgi disassembly results in cell-cycle arrest at the G2 stage, suggesting that accurate inheritance of the Golgi complex is monitored by a "Golgi mitotic checkpoint." Here, we discuss the mechanisms and regulation of the Golgi ribbon breakdown and briefly comment on how Golgi partitioning may inhibit G2/M transition.
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Affiliation(s)
- Daniela Corda
- Institute of Protein Biochemistry, National Research Council (CNR), Via Pietro Castellino 111, Naples, Italy.
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78
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Modular organization of the mammalian Golgi apparatus. Curr Opin Cell Biol 2012; 24:467-74. [PMID: 22726585 DOI: 10.1016/j.ceb.2012.05.009] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 05/29/2012] [Indexed: 02/07/2023]
Abstract
The Golgi apparatus is essential for post-translational modifications and sorting of proteins in the secretory pathway. In addition, it further performs a broad range of specialized functions. This functional diversity is achieved by combining basic morphological modules of cisternae into higher ordered structures. Linking cisternae into stacks that are further connected through tubules into a continuous Golgi ribbon greatly increases its efficiency and expands its repertoire of functions. During cell division, the different modules of the Golgi are inherited by different mechanisms to maintain its functional and morphological composition.
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79
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Truschel ST, Zhang M, Bachert C, Macbeth MR, Linstedt AD. Allosteric regulation of GRASP protein-dependent Golgi membrane tethering by mitotic phosphorylation. J Biol Chem 2012; 287:19870-5. [PMID: 22523075 PMCID: PMC3370171 DOI: 10.1074/jbc.m111.326256] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 02/23/2012] [Indexed: 11/06/2022] Open
Abstract
Mitotic phosphorylation of the conserved GRASP domain of GRASP65 disrupts its self-association, leading to a loss of Golgi membrane tethering, cisternal unlinking, and Golgi breakdown. Recently, the structural basis of the GRASP self-interaction was determined, yet the mechanism by which phosphorylation disrupts this activity is unknown. Here, we present the crystal structure of a GRASP phosphomimic containing an aspartic acid substitution for a serine residue (Ser-189) that in GRASP65 is phosphorylated by PLK1, causing a block in membrane tethering and Golgi ribbon formation. The structure revealed a conformational change in the GRASP internal ligand that prevented its insertion into the PDZ binding pocket, and gel filtration assays showed that this phosphomimic mutant exhibited a significant reduction in dimer formation. Interestingly, the structure also revealed an apparent propagation of conformational change from the site of phosphorylation to the shifted ligand, and alanine substitution of two residues (Glu-145 and Ser-146) at penultimate positions in this chain rescued dimer formation by the phosphomimic. These data reveal the structural basis of the phosphoinhibition of GRASP-mediated membrane tethering and provide a mechanism for its allosteric regulation.
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Affiliation(s)
- Steven T. Truschel
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Ming Zhang
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Collin Bachert
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Mark R. Macbeth
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Adam D. Linstedt
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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80
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Hiyoshi M, Takahashi-Makise N, Yoshidomi Y, Chutiwitoonchai N, Chihara T, Okada M, Nakamura N, Okada S, Suzu S. HIV-1 Nef perturbs the function, structure, and signaling of the Golgi through the Src kinase Hck. J Cell Physiol 2012; 227:1090-7. [PMID: 21567396 DOI: 10.1002/jcp.22825] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The interaction between HIV-1 Nef and the Src kinase Hck in macrophages has been shown to accelerate the progression to AIDS. We previously showed that Nef disturbed the N-glycosylation/trafficking of Fms, a cytokine receptor essential for maintaining macrophages in an anti-inflammatory state, in an Hck-dependent manner. Here, we show the underlying molecular mechanism of this effect. Using various Hck isoforms and their mutants and Golgi-targeting Hck mutants, we confirmed that Hck activation at the Golgi causes the Nef-induced Fms N-glycosylation defect. Importantly, we found that both the co-expression of Nef and Hck and the expression of a Golgi-targeted active Hck mutant caused alterations in the distribution of GM130, a Golgi protein that was shown to be required for efficient protein glycosylation. Moreover, the activation of Hck at the Golgi caused strong serine phosphorylation of the GM130-interacting Golgi structural protein GRASP65, which is known to induce Golgi cisternal unstacking. Using pharmacological inhibitors, we also found that the activation of Hck at the Golgi followed by the activation of the MAP kinase ERK-GRASP65 cascade is involved in the Fms N-glycosylation defect. These results suggest that Nef perturbs the structure and signaling of the Golgi by activating Hck at the Golgi, and thereby, induces the N-glycosylation/trafficking defect of Fms, which is in line with the idea that Src family kinases are crucial Golgi regulators.
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Affiliation(s)
- Masateru Hiyoshi
- Center for AIDS Research, Kumamoto University, Kumamoto-city, Kumamoto, Japan
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81
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Prydz K, Tveit H, Vedeler A, Saraste J. Arrivals and departures at the plasma membrane: direct and indirect transport routes. Cell Tissue Res 2012; 352:5-20. [DOI: 10.1007/s00441-012-1409-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 03/14/2012] [Indexed: 12/21/2022]
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82
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Sugawara T, Nakatsu D, Kii H, Maiya N, Adachi A, Yamamoto A, Kano F, Murata M. PKCδ and ε regulate the morphological integrity of the ER–Golgi intermediate compartment (ERGIC) but not the anterograde and retrograde transports via the Golgi apparatus. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:861-75. [DOI: 10.1016/j.bbamcr.2012.01.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 01/13/2012] [Accepted: 01/17/2012] [Indexed: 02/03/2023]
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83
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Kümmel D, Reinisch KM. Structure of Golgi transport proteins. Cold Spring Harb Perspect Biol 2011; 3:cshperspect.a007609. [PMID: 21813399 DOI: 10.1101/cshperspect.a007609] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The function of the Golgi has long been recognized to critically depend on vesicular transport from, to, and within its cisternae, involving constant membrane fission and fusion. These processes are mediated by Arf GTPases and coat proteins, and Rabs, tethers and SNARE proteins, respectively. In this article, we describe structural studies of Golgi coats and tethers and their interactions with SNAREs and GTPases as well as insights regarding membrane traffic processes that these have provided.
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Affiliation(s)
- Daniel Kümmel
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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84
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Affiliation(s)
| | - Adam D. Linstedt
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15232;
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85
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Abstract
The Golgi is an essential membrane-bound organelle in the secretary pathway of eukaryotic cells. In mammalian cells, the Golgi stacks are integrated into a continuous perinuclear ribbon, which poses a challenge for the daughter cells to inherit this membrane organelle during cell division. To facilitate proper partitioning, the mammalian Golgi ribbon is disassembled into vesicles in early mitosis. Following segregation into the daughter cells, a functional Golgi is reformed. Here we summarize our current understanding of the molecular mechanisms that control the mitotic Golgi disassembly and postmitotic reassembly cycle in mammalian cells.
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Affiliation(s)
- Yanzhuang Wang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA.
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86
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Seifert W, Kühnisch J, Maritzen T, Horn D, Haucke V, Hennies HC. Cohen syndrome-associated protein, COH1, is a novel, giant Golgi matrix protein required for Golgi integrity. J Biol Chem 2011; 286:37665-75. [PMID: 21865173 DOI: 10.1074/jbc.m111.267971] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Loss-of-function mutations in the gene COH1, also known as VPS13B, lead to autosomal recessive Cohen syndrome. However, the cellular distribution and function of the encoded protein COH1 (3997 amino acids), which lacks functional homologies to other mammalian proteins, have remained enigmatic. We show here that COH1 is a peripheral Golgi membrane protein that strongly co-localizes with the cis-Golgi matrix protein GM130. Consistent with its subcellular localization, COH1 depletion using RNAi causes fragmentation of the Golgi ribbon into ministacks. Disruption of Golgi organization observed in fibroblasts from Cohen syndrome patients suggests that Golgi dysfunction contributes to Cohen syndrome pathology. In conclusion, our findings establish COH1 as a Golgi-associated matrix protein required for Golgi integrity.
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Affiliation(s)
- Wenke Seifert
- Cologne Center for Genomics, Universität zu Köln, 50931 Köln, Germany.
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87
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Abstract
Since its first visualization in 1898, the Golgi has been a topic of intense morphological research. A typical mammalian Golgi consists of a pile of stapled cisternae, the Golgi stack, which is a key station for modification of newly synthesized proteins and lipids. Distinct stacks are interconnected by tubules to form the Golgi ribbon. At the entrance site of the Golgi, the cis-Golgi, vesicular tubular clusters (VTCs) form the intermediate between the endoplasmic reticulum and the Golgi stack. At the exit site of the Golgi, the trans-Golgi, the trans-Golgi network (TGN) is the major site of sorting proteins to distinct cellular locations. Golgi functioning can only be understood in light of its complex architecture, as was revealed by a range of distinct electron microscopy (EM) approaches. In this article, a general concept of mammalian Golgi architecture, including VTCs and the TGN, is described.
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Affiliation(s)
- Judith Klumperman
- Department of Cell Biology, University Medical Center Utrecht, Heidelberglaan 100, 3584CX Utrecht, The Netherlands.
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88
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Truschel ST, Sengupta D, Foote A, Heroux A, Macbeth MR, Linstedt AD. Structure of the membrane-tethering GRASP domain reveals a unique PDZ ligand interaction that mediates Golgi biogenesis. J Biol Chem 2011; 286:20125-9. [PMID: 21515684 PMCID: PMC3121478 DOI: 10.1074/jbc.c111.245324] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Indexed: 11/06/2022] Open
Abstract
Biogenesis of the ribbon-like membrane network of the mammalian Golgi requires membrane tethering by the conserved GRASP domain in GRASP65 and GRASP55, yet the tethering mechanism is not fully understood. Here, we report the crystal structure of the GRASP55 GRASP domain, which revealed an unusual arrangement of two tandem PDZ folds that more closely resemble prokaryotic PDZ domains. Biochemical and functional data indicated that the interaction between the ligand-binding pocket of PDZ1 and an internal ligand on PDZ2 mediates the GRASP self-interaction, and structural analyses suggest that this occurs via a unique mode of internal PDZ ligand recognition. Our data uncover the structural basis for ligand specificity and provide insight into the mechanism of GRASP-dependent membrane tethering of analogous Golgi cisternae.
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Affiliation(s)
- Steven T. Truschel
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 and
| | - Debrup Sengupta
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 and
| | - Adam Foote
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 and
| | - Annie Heroux
- the National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973
| | - Mark R. Macbeth
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 and
| | - Adam D. Linstedt
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 and
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89
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Abstract
The eukaryotic Golgi apparatus is characterized by a stack of flattened cisternae that are surrounded by transport vesicles. The organization and function of the Golgi require Golgi matrix proteins, including GRASPs and golgins, which exist primarily as fiber-like bridges between Golgi cisternae or between cisternae and vesicles. In this review, we highlight recent findings on Golgi matrix proteins, including their roles in maintaining the Golgi structure, vesicle tethering, and novel, unexpected functions. These new discoveries further our understanding of the molecular mechanisms that maintain the structure and the function of the Golgi, as well as its relationship with other cellular organelles such as the centrosome.
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90
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Feinstein TN, Wehbi VL, Ardura JA, Wheeler DS, Ferrandon S, Gardella TJ, Vilardaga JP. Retromer terminates the generation of cAMP by internalized PTH receptors. Nat Chem Biol 2011; 7:278-84. [PMID: 21445058 PMCID: PMC3079799 DOI: 10.1038/nchembio.545] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Accepted: 01/24/2011] [Indexed: 12/12/2022]
Abstract
The generation of cAMP by G protein-coupled receptors (GPCRs) and its termination are currently thought to occur exclusively at the plasma membrane of cells. Under existing models of receptor regulation, this signal is primarily restricted by desensitization of the receptors through their binding to β-arrestins. However, this paradigm is not consistent with recent observations that the parathyroid hormone receptor type 1 (PTHR) continues to stimulate cAMP production even after receptor internalization, as β-arrestins are known to rapidly bind and internalize activated PTHR. Here we show that binding to β-arrestin1 prolongs rather than terminates the generation of cAMP by PTHR, and that cAMP generation correlates with the persistence of arrestin-receptor complexes on endosomes. PTHR signaling is instead turned off by the retromer complex, which regulates the movement of internalized receptor from endosomes to the Golgi apparatus. Thus, binding by the retromer complex regulates the sustained generation of cAMP triggered by an internalized GPCR.
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Affiliation(s)
- Timothy N Feinstein
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
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91
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Abstract
The mammalian GRASPs (Golgi reassembly stacking proteins) GRASP65 and GRASP55 were first discovered more than a decade ago as factors involved in the stacking of Golgi cisternae. Since then, orthologues have been identified in many different organisms and GRASPs have been assigned new roles that may seem disconnected. In vitro, GRASPs have been shown to have the biochemical properties of Golgi stacking factors, but the jury is still out as to whether they act as such in vivo. In mammalian cells, GRASP65 and GRASP55 are required for formation of the Golgi ribbon, a structure which is fragmented in mitosis owing to the phosphorylation of a number of serine and threonine residues situated in its C-terminus. Golgi ribbon unlinking is in turn shown to be part of a mitotic checkpoint. GRASP65 also seems to be the key target of signalling events leading to re-orientation of the Golgi during cell migration and its breakdown during apoptosis. Interestingly, the Golgi ribbon is not a feature of lower eukaryotes, yet a GRASP homologue is present in the genome of Encephalitozoon cuniculi, suggesting they have other roles. GRASPs have no identified function in bulk anterograde protein transport along the secretory pathway, but some cargo-specific trafficking roles for GRASPs have been discovered. Furthermore, GRASP orthologues have recently been shown to mediate the unconventional secretion of the cytoplasmic proteins AcbA/Acb1, in both Dictyostelium discoideum and yeast, and the Golgi bypass of a number of transmembrane proteins during Drosophila development. In the present paper, we review the multiple roles of GRASPs.
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92
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Abstract
The Golgi apparatus lies at the heart of the secretory pathway where it receives, modifies and sorts protein cargo to the proper intracellular or extracellular location. Although this secretory function is highly conserved throughout the eukaryotic kingdom, the structure of the Golgi complex is arranged very differently among species. In particular, Golgi membranes in vertebrate cells are integrated into a single compact entity termed the Golgi ribbon that is normally localized in the perinuclear area and in close vicinity to the centrosomes. This organization poses a challenge for cell division when the single Golgi ribbon needs to be partitioned into the two daughter cells. To ensure faithful inheritance in the progeny, the Golgi ribbon is divided in three consecutive steps in mitosis, namely disassembly, partitioning and reassembly. However, the structure of the Golgi ribbon is only present in higher animals and Golgi disassembly during mitosis is not ubiquitous in all organisms. Therefore, there must be unique reasons to build up the Golgi in this particular conformation and to preserve it over generations. In this review, we first highlight the diversity of the Golgi architecture in different organisms and revisit the concept of the Golgi ribbon. Following on, we discuss why the ribbon is needed and how it forms in vertebrate cells. Lastly, we conclude with likely purposes of mitotic ribbon disassembly and further propose mechanisms by which it regulates mitosis.
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Affiliation(s)
- Jen-Hsuan Wei
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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93
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Structural organization of the Golgi apparatus. Curr Opin Cell Biol 2011; 23:85-93. [DOI: 10.1016/j.ceb.2010.10.004] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 10/07/2010] [Accepted: 10/17/2010] [Indexed: 11/21/2022]
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94
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Sengupta D, Linstedt AD. Mitotic inhibition of GRASP65 organelle tethering involves Polo-like kinase 1 (PLK1) phosphorylation proximate to an internal PDZ ligand. J Biol Chem 2010; 285:39994-40003. [PMID: 20937827 PMCID: PMC3000981 DOI: 10.1074/jbc.m110.189449] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Indexed: 11/06/2022] Open
Abstract
GRASP65 links cis-Golgi cisternae via a homotypic, N-terminal PDZ interaction, and its mitotic phosphorylation disrupts this activity. Neither the identity of the PDZ ligand involved in the GRASP65 self-interaction nor the mechanism by which phosphorylation inhibits its interaction is known. Phospho-mimetic mutation of known cyclin-dependent kinase 1/cyclin B sites, all of which are in the C-terminal "regulatory domain" of the molecule, failed to block organelle tethering. However, we identified a site phosphorylated by Polo-like kinase 1 (PLK1) in the GRASP65 N-terminal domain for which mutation to aspartic acid blocked tethering and alanine substitution prevented mitotic Golgi unlinking. Further, using interaction assays, we discovered an internal PDZ ligand adjacent to the PLK phosphorylation site that was required for tethering. These results reveal the mechanism of phosphoinhibition as direct inhibition by PLK1 of the PDZ ligand underlying the GRASP65 self-interaction.
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Affiliation(s)
- Debrup Sengupta
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Adam D. Linstedt
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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95
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Farhan H, Wendeler MW, Mitrovic S, Fava E, Silberberg Y, Sharan R, Zerial M, Hauri HP. MAPK signaling to the early secretory pathway revealed by kinase/phosphatase functional screening. ACTA ACUST UNITED AC 2010; 189:997-1011. [PMID: 20548102 PMCID: PMC2886346 DOI: 10.1083/jcb.200912082] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
To what extent the secretory pathway is regulated by cellular signaling is unknown. In this study, we used RNA interference to explore the function of human kinases and phosphatases in controlling the organization of and trafficking within the secretory pathway. We identified 122 kinases/phosphatases that affect endoplasmic reticulum (ER) export, ER exit sites (ERESs), and/or the Golgi apparatus. Numerous kinases/phosphatases regulate the number of ERESs and ER to Golgi protein trafficking. Among the pathways identified, the Raf-MEK (MAPK/ERK [extracellular signal-regulated kinase] kinase)-ERK cascade, including its regulatory proteins CNK1 (connector enhancer of the kinase suppressor of Ras-1) and neurofibromin, controls the number of ERESs via ERK2, which targets Sec16, a key regulator of ERESs and COPII (coat protein II) vesicle biogenesis. Our analysis reveals an unanticipated complexity of kinase/phosphatase-mediated regulation of the secretory pathway, uncovering a link between growth factor signaling and ER export.
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Affiliation(s)
- Hesso Farhan
- Biozentrum, Universität Basel, 4056 Basel, Switzerland
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96
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Levi SK, Bhattacharyya D, Strack RL, Austin JR, Glick BS. The yeast GRASP Grh1 colocalizes with COPII and is dispensable for organizing the secretory pathway. Traffic 2010; 11:1168-79. [PMID: 20573068 DOI: 10.1111/j.1600-0854.2010.01089.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In mammalian cells, the 'Golgi reassembly and stacking protein' (GRASP) family has been implicated in Golgi stacking, but the broader functions of GRASP proteins are still unclear. The yeast Saccharomyces cerevisiae contains a single non-essential GRASP homolog called Grh1. However, Golgi cisternae in S. cerevisiae are not organized into stacks, so a possible structural role for Grh1 has been difficult to test. Here, we examined the localization and function of Grh1 in S. cerevisiae and in the related yeast Pichia pastoris, which has stacked Golgi cisternae. In agreement with earlier studies indicating that Grh1 interacts with coat protein II (COPII) vesicle coat proteins, we find that Grh1 colocalizes with COPII at transitional endoplasmic reticulum (tER) sites in both yeasts. Deletion of P. pastoris Grh1 had no obvious effect on the structure of tER-Golgi units. To test the role of S. cerevisiae Grh1, we exploited the observation that inhibiting ER export in S. cerevisiae generates enlarged tER sites that are often associated with the cis Golgi. This tER-Golgi association was preserved in the absence of Grh1. The combined data suggest that Grh1 acts early in the secretory pathway, but is dispensable for the organization of secretory compartments.
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Affiliation(s)
- Stephanie K Levi
- Department of Molecular Genetics and Cell Biology, The University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA
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97
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Koegler E, Bonnon C, Waldmeier L, Mitrovic S, Halbeisen R, Hauri HP. p28, a novel ERGIC/cis Golgi protein, required for Golgi ribbon formation. Traffic 2010; 11:70-89. [PMID: 19948005 DOI: 10.1111/j.1600-0854.2009.01009.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The mammalian Golgi apparatus consists of individual cisternae that are stacked in a polarized manner to form the compact zones of the Golgi. Several stacks are linked to form a ribbon via dynamic lateral bridges. The determinants required for maintaining the characteristic Golgi structure are incompletely understood. Here, we have characterized p28, a new gamma-subfamily member of p24 membrane proteins. p28 localized to endoplasmic reticulum-Golgi intermediate compartment (ERGIC) and cis Golgi and accumulated in the ERGIC upon Brefeldin A treatment, typical for a protein cycling in the early secretory pathway. p28 interacted with a subset of p24 proteins. Its depletion by small interfering RNA (siRNA) led to fragmentation of the Golgi without affecting the overall organization of microtubules but considerably reducing the amount of acetylated tubulin. The distribution of COPI and tethers, including GM130, was not affected. At the ultrastructural level, the Golgi fragments appeared as mini-stacks with apparently unchanged cis-trans topology. Golgi fragmentation did not impair anterograde or retrograde traffic. Fluorescence recovery after photobleaching (FRAP) experiments revealed that silencing p28 prevents protein exchange between Golgi stacks during reassembly after Brefeldin A-induced Golgi breakdown. These results show that the formation of a Golgi ribbon requires the structural membrane protein p28 in addition to previously identified SNAREs, coat proteins and tethers.
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Affiliation(s)
- Eva Koegler
- Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland
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98
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Phosphorylation and membrane dissociation of the ARF exchange factor GBF1 in mitosis. Biochem J 2010; 427:401-12. [PMID: 20175751 DOI: 10.1042/bj20091681] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Secretory protein trafficking is arrested and the Golgi apparatus fragmented when mammalian cells enter mitosis. These changes are thought to facilitate cell-cycle progression and Golgi inheritance, and are brought about through the actions of mitotically active protein kinases. To better understand how the Golgi apparatus undergoes mitotic fragmentation we have sought to identify novel Golgi targets for mitotic kinases. We report in the present paper the identification of the ARF (ADP-ribosylation factor) exchange factor GBF1 (Golgi-specific brefeldin A-resistant guanine nucleotide-exchange factor 1) as a Golgi phosphoprotein. GBF1 is phosphorylated by CDK1 (cyclin-dependent kinase 1)-cyclin B in mitosis, which results in its dissociation from Golgi membranes. Consistent with a reduced level of GBF1 activity at the Golgi membrane there is a reduction in levels of membrane-associated GTP-bound ARF in mitotic cells. Despite the reduced levels of membrane-bound GBF1 and ARF, COPI (coat protein I) binding to the Golgi membrane appears unaffected in mitotic cells. Surprisingly, this pool of COPI is dependent upon GBF1 for its recruitment to the membrane, suggesting that a low level of GBF1 activity persists in mitosis. We propose that the phosphorylation and membrane dissociation of GBF1 and the consequent reduction in ARF-GTP levels in mitosis are important for changes in Golgi dynamics and possibly other mitotic events mediated through effectors other than the COPI vesicle coat.
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99
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Abstract
The mammalian Golgi apparatus is characterized by a ribbon-like organization adjacent to the centrosome during interphase and extensive fragmentation and dispersal away from the centrosome during mitosis. It is not clear whether this dynamic association between the Golgi and centrosome is of functional significance. We discuss recent findings indicating that the Golgi–centrosome relationship may be important for directional protein transport and centrosome positioning, which are both required for cell polarization. We also summarize our current knowledge of the link between Golgi organization and cell cycle progression.
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Affiliation(s)
- Christine Sütterlin
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA.
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100
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Abstract
Yip1A depletion leads to reorganization of the ER into stacked and concentrically whorled membranes as well as a slowing of cargo export. The network dispersal function of Yip1A depends on a conserved residue. Thus, a conserved Yip1A-mediated ER network dispersal mechanism may regulate the protein export function of the organelle. The structure of the endoplasmic reticulum (ER) undergoes highly regulated changes in specialized cell types. One frequently observed type of change is its reorganization into stacked and concentrically whorled membranes, but the underlying mechanisms and functional relevance for cargo export are unknown. Here, we identify Yip1A, a conserved membrane protein that cycles between the ER and early Golgi, as a key mediator of ER organization. Yip1A depletion led to restructuring of the network into multiple, micrometer-sized concentric whorls. Membrane stacking and whorl formation coincided with a marked slowing of coat protein (COP)II-mediated protein export. Furthermore, whorl formation driven by exogenous expression of an ER protein with no role in COPII function also delayed cargo export. Thus, the slowing of protein export induced by Yip1A depletion may be attributed to a proximal role for Yip1A in regulating ER network dispersal. The ER network dispersal function of Yip1A was blocked by alteration of a single conserved amino acid (E95K) in its N-terminal cytoplasmic domain. These results reveal a conserved Yip1A-mediated mechanism for ER membrane organization that may serve to regulate cargo exit from the organelle.
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Affiliation(s)
- Kaitlyn M Dykstra
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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