1
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Specific subdomain localization of ER resident proteins and membrane contact sites resolved by electron microscopy. Eur J Cell Biol 2021; 100:151180. [PMID: 34653930 DOI: 10.1016/j.ejcb.2021.151180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/23/2021] [Accepted: 09/28/2021] [Indexed: 11/21/2022] Open
Abstract
The endoplasmic reticulum (ER) is a large, single-copy, membrane-bound organelle that comprises an elaborate 3D network of diverse structural subdomains, including highly curved tubules, flat sheets, and parts that form contacts with nearly every other organelle. The dynamic and complex organization of the ER poses a major challenge on understanding how its functioning - maintenance of the structure, distribution of its functions and communication with other organelles - is orchestrated. In this study, we resolved a unique localization profile within the ER network for several resident ER proteins representing a broad range of functions associated with the ER using immuno-electron microscopy and calculation of a relative labeling index (RLI). Our results demonstrated the effect of changing cellular environment on protein localization and highlighted the importance of correct protein expression level when analyzing its localization at subdomain resolution. We present new software tools for anonymization of images for blind analysis and for quantitative assessment of membrane contact sites (MCSs) from thin section transmission electron microscopy micrographs. The analysis of ER-mitochondria contacts suggested the presence of at least three different types of MCSs that responded differently to changes in cellular lipid loading status.
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2
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Sołtysik K, Ohsaki Y, Tatematsu T, Cheng J, Maeda A, Morita SY, Fujimoto T. Nuclear lipid droplets form in the inner nuclear membrane in a seipin-independent manner. J Cell Biol 2021; 220:211592. [PMID: 33315072 PMCID: PMC7737703 DOI: 10.1083/jcb.202005026] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 09/25/2020] [Accepted: 11/11/2020] [Indexed: 01/09/2023] Open
Abstract
Nuclear lipid droplets (LDs) in hepatocytes are derived from precursors of very-low-density lipoprotein in the ER lumen, but it is not known how cells lacking the lipoprotein secretory function form nuclear LDs. Here, we show that the inner nuclear membrane (INM) of U2OS cells harbors triglyceride synthesis enzymes, including ACSL3, AGPAT2, GPAT3/GPAT4, and DGAT1/DGAT2, and generates nuclear LDs in situ. mTOR inhibition increases nuclear LDs by inducing the nuclear translocation of lipin-1 phosphatidic acid (PA) phosphatase. Seipin, a protein essential for normal cytoplasmic LD formation in the ER, is absent in the INM. Knockdown of seipin increases nuclear LDs and PA in the nucleus, whereas seipin overexpression decreases these. Seipin knockdown also up-regulates lipin-1β expression, and lipin-1 knockdown decreases the effect of seipin knockdown on nuclear LDs without affecting PA redistribution. These results indicate that seipin is not directly involved in nuclear LD formation but instead restrains it by affecting lipin-1 expression and intracellular PA distribution.
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Affiliation(s)
- Kamil Sołtysik
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yuki Ohsaki
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tsuyako Tatematsu
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Jinglei Cheng
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Asami Maeda
- Laboratory of Molecular Cell Biology, Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Shin-Ya Morita
- Department of Pharmacy, Shiga University of Medical Science Hospital, Otsu City, Shiga, Japan
| | - Toyoshi Fujimoto
- Laboratory of Molecular Cell Biology, Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo, Japan
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3
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Kumar D, Lak B, Suntio T, Vihinen H, Belevich I, Viita T, Xiaonan L, Vartiainen A, Vartiainen M, Varjosalo M, Jokitalo E. RTN4B interacting protein FAM134C promotes ER membrane curvature and has a functional role in autophagy. Mol Biol Cell 2021; 32:1158-1170. [PMID: 33826365 PMCID: PMC8351555 DOI: 10.1091/mbc.e20-06-0409] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The endoplasmic reticulum (ER) is composed of a controlled ratio of sheets and tubules, which are maintained by several proteins with multiple functions. Reticulons (RTNs), especially RTN4, and DP1/Yop1p family members are known to induce ER membrane curvature. RTN4B is the main RTN4 isoform expressed in nonneuronal cells. In this study, we identified FAM134C as a RTN4B interacting protein in mammalian, nonneuronal cells. FAM134C localized specifically to the ER tubules and sheet edges. Ultrastructural analysis revealed that overexpression of FAM134C induced the formation of unbranched, long tubules or dense globular structures composed of heavily branched narrow tubules. In both cases, tubules were nonmotile. ER tubulation was dependent on the reticulon homology domain (RHD) close to the N-terminus. FAM134C plays a role in the autophagy pathway as its level elevated significantly upon amino acid starvation but not during ER stress. Moreover, FAM134C depletion reduced the number and size of autophagic structures and the amount of ER as a cargo within autophagic structures under starvation conditions. Dominant-negative expression of FAM134C forms with mutated RHD or LC3 interacting region also led to a reduced number of autophagic structures. Our results suggest that FAM134C provides a link between regulation of ER architecture and ER turnover by promoting ER tubulation required for subsequent ER fragmentation and engulfment into autophagosomes.
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Affiliation(s)
| | - Behnam Lak
- Cell and Tissue Dynamics Research Program
| | | | - Helena Vihinen
- Cell and Tissue Dynamics Research Program.,Electron Microscopy Unit, and
| | - Ilya Belevich
- Cell and Tissue Dynamics Research Program.,Electron Microscopy Unit, and
| | | | - Liu Xiaonan
- Molecular Systems Biology Research Group and Proteomics Unit, Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, 00014 Helsinki, Finland
| | | | | | - Markku Varjosalo
- Molecular Systems Biology Research Group and Proteomics Unit, Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, 00014 Helsinki, Finland
| | - Eija Jokitalo
- Cell and Tissue Dynamics Research Program.,Electron Microscopy Unit, and
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4
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Guo H, Wei JH, Zhang Y, Seemann J. Importin α phosphorylation promotes TPX2 activation by GM130 to control astral microtubules and spindle orientation. J Cell Sci 2021; 134:jcs.258356. [PMID: 33526712 DOI: 10.1242/jcs.258356] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Accepted: 01/11/2021] [Indexed: 01/10/2023] Open
Abstract
Spindle orientation is important in multiple developmental processes as it determines cell fate and function. The orientation of the spindle depends on the assembly of a proper astral microtubule network. Here, we report that the spindle assembly factor TPX2 regulates astral microtubules. TPX2 in the spindle pole area is activated by GM130 (GOLGA2) on Golgi membranes to promote astral microtubule growth. GM130 relieves TPX2 inhibition by competing for importin α1 (KPNA2) binding. Mitotic phosphorylation of importin α at serine 62 (S62) by CDK1 switches its substrate preference from TPX2 to GM130, thereby enabling competition-based activation. Importin α S62A mutation impedes local TPX2 activation and compromises astral microtubule formation, ultimately resulting in misoriented spindles. Blocking the GM130-importin α-TPX2 pathway impairs astral microtubule growth. Our results reveal a novel role for TPX2 in the organization of astral microtubules. Furthermore, we show that the substrate preference of the important mitotic modulator importin α is regulated by CDK1-mediated phosphorylation.
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Affiliation(s)
- Haijing Guo
- Department of Cell Biology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Jen-Hsuan Wei
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Yijun Zhang
- Department of Cell Biology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Joachim Seemann
- Department of Cell Biology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
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5
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Valbuena FM, Fitzgerald I, Strack RL, Andruska N, Smith L, Glick BS. A photostable monomeric superfolder green fluorescent protein. Traffic 2020; 21:534-544. [PMID: 32415747 DOI: 10.1111/tra.12737] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 05/09/2020] [Accepted: 05/10/2020] [Indexed: 11/30/2022]
Abstract
The green fluorescent protein (GFP) from Aequorea victoria has been engineered extensively in the past to generate variants suitable for protein tagging. Early efforts produced the enhanced variant EGFP and its monomeric derivative mEGFP, which have useful photophysical properties, as well as superfolder GFP, which folds efficiently under adverse conditions. We previously generated msGFP, a monomeric superfolder derivative of EGFP. Unfortunately, compared to EGFP, msGFP and other superfolder GFP variants show faster photobleaching. We now describe msGFP2, which retains monomeric superfolder properties while being as photostable as EGFP. msGFP2 contains modified N- and C-terminal peptides that are expected to reduce nonspecific interactions. Compared to EGFP and mEGFP, msGFP2 is less prone to disturbing the functions of certain partner proteins. For general-purpose protein tagging, msGFP2 may be the best available derivative of A. victoria GFP.
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Affiliation(s)
- Fernando M Valbuena
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois, USA
| | - Ivy Fitzgerald
- Graduate Program in Biophysical Sciences, The University of Chicago, Chicago, Illinois, USA
| | - Rita L Strack
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois, USA
| | - Neal Andruska
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois, USA
| | - Luke Smith
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois, USA
| | - Benjamin S Glick
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois, USA
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6
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Hernández-Pérez S, Vainio M, Kuokkanen E, Šuštar V, Petrov P, Forstén S, Paavola V, Rajala J, Awoniyi LO, Sarapulov AV, Vihinen H, Jokitalo E, Bruckbauer A, Mattila PK. B cells rapidly target antigen and surface-derived MHCII into peripheral degradative compartments. J Cell Sci 2019; 133:jcs.235192. [PMID: 31780582 DOI: 10.1242/jcs.235192] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 11/20/2019] [Indexed: 11/20/2022] Open
Abstract
In order to mount high-affinity antibody responses, B cells internalise specific antigens and process them into peptides loaded onto MHCII for presentation to T helper cells (TH cells). While the biochemical principles of antigen processing and MHCII loading have been well dissected, how the endosomal vesicle system is wired to enable these specific functions remains much less studied. Here, we performed a systematic microscopy-based analysis of antigen trafficking in B cells to reveal its route to the MHCII peptide-loading compartment (MIIC). Surprisingly, we detected fast targeting of internalised antigen into peripheral acidic compartments that possessed the hallmarks of the MIIC and also showed degradative capacity. In these vesicles, internalised antigen converged rapidly with membrane-derived MHCII and partially overlapped with cathepsin-S and H2-M, both required for peptide loading. These early compartments appeared heterogenous and atypical as they contained a mixture of both early and late endosomal markers, indicating a specialized endosomal route. Together, our data suggest that, in addition to in the previously reported perinuclear late endosomal MIICs, antigen processing and peptide loading could have already started in these specialized early peripheral acidic vesicles (eMIIC) to support fast peptide-MHCII presentation.
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Affiliation(s)
- Sara Hernández-Pérez
- Institute of Biomedicine, and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland.,Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Marika Vainio
- Institute of Biomedicine, and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland.,Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Elina Kuokkanen
- Institute of Biomedicine, and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
| | - Vid Šuštar
- Institute of Biomedicine, and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
| | - Petar Petrov
- Institute of Biomedicine, and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland.,Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Sofia Forstén
- Institute of Biomedicine, and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland.,Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Vilma Paavola
- Institute of Biomedicine, and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
| | - Johanna Rajala
- Institute of Biomedicine, and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
| | - Luqman O Awoniyi
- Institute of Biomedicine, and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland.,Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Alexey V Sarapulov
- Institute of Biomedicine, and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland.,Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Helena Vihinen
- Institute of Biotechnology, Electron Microscopy Unit, 00014 University of Helsinki, Finland
| | - Eija Jokitalo
- Institute of Biotechnology, Electron Microscopy Unit, 00014 University of Helsinki, Finland
| | - Andreas Bruckbauer
- Facility for Imaging by Light Microscopy (FILM), National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Pieta K Mattila
- Institute of Biomedicine, and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland .,Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
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7
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Kumar D, Golchoubian B, Belevich I, Jokitalo E, Schlaitz AL. REEP3 and REEP4 determine the tubular morphology of the endoplasmic reticulum during mitosis. Mol Biol Cell 2019; 30:1377-1389. [PMID: 30995177 PMCID: PMC6724692 DOI: 10.1091/mbc.e18-11-0698] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The endoplasmic reticulum (ER) is extensively remodeled during metazoan open mitosis. However, whether the ER becomes more tubular or more cisternal during mitosis is controversial, and dedicated factors governing the morphology of the mitotic ER have remained elusive. Here, we describe the ER membrane proteins REEP3 and REEP4 as major determinants of ER morphology in metaphase cells. REEP3/4 are specifically required for generating the high-curvature morphology of mitotic ER and promote ER tubulation through their reticulon homology domains (RHDs). This ER-shaping activity of REEP3/4 is distinct from their previously described function to clear ER from metaphase chromatin. We further show that related REEP proteins do not contribute to mitotic ER shaping and provide evidence that the REEP3/4 carboxyterminus mediates regulation of the proteins. These findings confirm that ER converts to higher curvature during mitosis, identify REEP3/4 as specific and crucial morphogenic factors mediating ER tubulation during mitosis, and define the first cell cycle-specific role for RHD proteins.
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Affiliation(s)
- Darshan Kumar
- Cell and Molecular Biology Program, University of Helsinki, FI-00014 Helsinki, Finland
| | - Banafsheh Golchoubian
- Center for Molecular Biology of Heidelberg University (ZMBH), D-69120 Heidelberg, Germany
| | - Ilya Belevich
- Cell and Molecular Biology Program, University of Helsinki, FI-00014 Helsinki, Finland.,Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, FI-00014 Helsinki, Finland
| | - Eija Jokitalo
- Cell and Molecular Biology Program, University of Helsinki, FI-00014 Helsinki, Finland.,Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, FI-00014 Helsinki, Finland
| | - Anne-Lore Schlaitz
- Center for Molecular Biology of Heidelberg University (ZMBH), D-69120 Heidelberg, Germany
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8
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Sołtysik K, Ohsaki Y, Tatematsu T, Cheng J, Fujimoto T. Nuclear lipid droplets derive from a lipoprotein precursor and regulate phosphatidylcholine synthesis. Nat Commun 2019; 10:473. [PMID: 30692541 PMCID: PMC6349838 DOI: 10.1038/s41467-019-08411-x] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 01/10/2019] [Indexed: 02/07/2023] Open
Abstract
The origin and physiological significance of lipid droplets (LDs) in the nucleus is not clear. Here we show that nuclear LDs in hepatocytes are derived from apolipoprotein B (ApoB)-free lumenal LDs, a precursor to very low-density lipoproprotein (VLDL) generated in the ER lumen by microsomal triglyceride transfer protein. ApoB-free lumenal LDs accumulate under ER stress, grow within the lumen of the type I nucleoplasmic reticulum, and turn into nucleoplasmic LDs by disintegration of the surrounding inner nuclear membrane. Oleic acid with or without tunicamycin significantly increases the formation of nucleoplasmic LDs, to which CTP:phosphocholine cytidylyltransferase α (CCTα) is recruited, resulting in activation of phosphatidylcholine (PC) synthesis. Perilipin-3 competes with CCTα in binding to nucleoplasmic LDs, and thus, knockdown and overexpression of perilipin-3 increases and decreases PC synthesis, respectively. The results indicate that nucleoplasmic LDs in hepatocytes constitute a feedback mechanism to regulate PC synthesis in accordance with ER stress. The origin and physiological significance of lipid droplets (LDs) in the nucleus is not clear. Here authors show that nucleoplasmic LDs in hepatocytes are derived from apolipoprotein B (ApoB)-free lumenal LDs and constitute a feedback mechanism to regulate PC synthesis in accordance with ER stress.
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Affiliation(s)
- Kamil Sołtysik
- Department of Molecular Cell Biology and Anatomy, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Yuki Ohsaki
- Department of Molecular Cell Biology and Anatomy, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan.
| | - Tsuyako Tatematsu
- Department of Molecular Cell Biology and Anatomy, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Jinglei Cheng
- Department of Molecular Cell Biology and Anatomy, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Toyoshi Fujimoto
- Department of Molecular Cell Biology and Anatomy, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan.
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9
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Witkos TM, Chan WL, Joensuu M, Rhiel M, Pallister E, Thomas-Oates J, Mould AP, Mironov AA, Biot C, Guerardel Y, Morelle W, Ungar D, Wieland FT, Jokitalo E, Tassabehji M, Kornak U, Lowe M. GORAB scaffolds COPI at the trans-Golgi for efficient enzyme recycling and correct protein glycosylation. Nat Commun 2019; 10:127. [PMID: 30631079 PMCID: PMC6328613 DOI: 10.1038/s41467-018-08044-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 12/06/2018] [Indexed: 01/08/2023] Open
Abstract
COPI is a key mediator of protein trafficking within the secretory pathway. COPI is recruited to the membrane primarily through binding to Arf GTPases, upon which it undergoes assembly to form coated transport intermediates responsible for trafficking numerous proteins, including Golgi-resident enzymes. Here, we identify GORAB, the protein mutated in the skin and bone disorder gerodermia osteodysplastica, as a component of the COPI machinery. GORAB forms stable domains at the trans-Golgi that, via interactions with the COPI-binding protein Scyl1, promote COPI recruitment to these domains. Pathogenic GORAB mutations perturb Scyl1 binding or GORAB assembly into domains, indicating the importance of these interactions. Loss of GORAB causes impairment of COPI-mediated retrieval of trans-Golgi enzymes, resulting in a deficit in glycosylation of secretory cargo proteins. Our results therefore identify GORAB as a COPI scaffolding factor, and support the view that defective protein glycosylation is a major disease mechanism in gerodermia osteodysplastica.
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Affiliation(s)
- Tomasz M Witkos
- School of Biology, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - Wing Lee Chan
- Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Institut fuer Medizinische Genetik und Humangenetik, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, 13353, Germany
- FG Development & Disease, Max Planck Institut fuer Molekulare Genetik, Berlin, 14195, Germany
| | - Merja Joensuu
- Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, 00014, Finland
- Clem Jones Centre of Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Brisbane, QLD 4072, Australia
- Minerva Foundation Institute for Medical Research, 00290, Helsinki, Finland
| | - Manuel Rhiel
- Heidelberg University Biochemistry Center, Heidelberg University, Heidelberg, 69120, Germany
| | - Ed Pallister
- Department of Chemistry, University of York, York, YO10 5DG, UK
| | | | - A Paul Mould
- School of Biology, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - Alex A Mironov
- School of Biology, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - Christophe Biot
- Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000, Lille, France
| | - Yann Guerardel
- Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000, Lille, France
| | - Willy Morelle
- Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000, Lille, France
| | - Daniel Ungar
- Department of Biology, University of York, York, YO10 5DD, UK
| | - Felix T Wieland
- Heidelberg University Biochemistry Center, Heidelberg University, Heidelberg, 69120, Germany
| | - Eija Jokitalo
- Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, 00014, Finland
| | - May Tassabehji
- School of Biology, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
- Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester Academic Health Sciences Centre (MAHSC), Manchester, M13 9WL, UK
| | - Uwe Kornak
- Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Institut fuer Medizinische Genetik und Humangenetik, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, 13353, Germany
- FG Development & Disease, Max Planck Institut fuer Molekulare Genetik, Berlin, 14195, Germany
| | - Martin Lowe
- School of Biology, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK.
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10
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iTRAQ-based proteome profiling of hyposaline responses in zygotes of the Pacific oyster Crassostrea gigas. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2018; 30:14-24. [PMID: 30771561 DOI: 10.1016/j.cbd.2018.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 12/06/2018] [Accepted: 12/07/2018] [Indexed: 11/22/2022]
Abstract
Low salinity treatment is proven to be the practical polyploidy inducing method for shellfish with advantages of lower cost, higher operability and reliable food security. However, little is known about the possible molecular mechanism of hypotonic induction. In this study, isobaric tags for relative and absolute quantitation (iTRAQ) based proteomic profiling was pursued to investigate the responses of zygotes of the Pacific oyster Crassostrea gigas to low salinity. A total of 2235 proteins were identified and 87 proteins were considered differentially expressed, of which 14 were up-regulated and 69 were down-regulated. Numerous functional proteins including ADP ribosylation factor 2, DNA repair protein Rad50, splicing factor 3B, tubulin-specific Chaperone D were significantly changed in abundance, and were involved in various biology processes including energy generation, vesicle trafficking, DNA/RNA/protein metabolism and cytoskeleton modification, indicating the prominent modulation of cell division and embryonic development. Parallel reaction monitoring (PRM) analyses were carried out for validation of the expression levels of differentially expressed proteins (DEPs), which indicated high reliability of the proteomic results. Our study not only demonstrated the proteomic alterations in oyster zygotes under low salinity, but also provided, in part, clues to the relatively lower hatching rate and higher mortality of induced larvae. Above all, this study presents a valuable foundation for further studies on mechanisms of hypotonic induction.
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11
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Abstract
A portfolio is presented documenting economic, high-resolution correlative focused ion beam scanning electron microscopy (FIB/SEM) in routine, comprising: (i) the use of custom-labeled slides and coverslips, (ii) embedding of cells in thin, or ultra-thin resin layers for correlative light and electron microscopy (CLEM) and (iii) the claim to reach the highest resolution possible with FIB/SEM in xyz. Regions of interest (ROIs) defined in light microscope (LM), can be relocated quickly and precisely in SEM. As proof of principle, HeLa cells were investigated in 3D context at all stages of the cell cycle, documenting ultrastructural changes during mitosis: nuclear envelope breakdown and reassembly, Golgi degradation and reconstitution and the formation of the midzone and midbody.
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12
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Gendron L, Cahill CM, von Zastrow M, Schiller PW, Pineyro G. Molecular Pharmacology of δ-Opioid Receptors. Pharmacol Rev 2017; 68:631-700. [PMID: 27343248 DOI: 10.1124/pr.114.008979] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Opioids are among the most effective analgesics available and are the first choice in the treatment of acute severe pain. However, partial efficacy, a tendency to produce tolerance, and a host of ill-tolerated side effects make clinically available opioids less effective in the management of chronic pain syndromes. Given that most therapeutic opioids produce their actions via µ-opioid receptors (MOPrs), other targets are constantly being explored, among which δ-opioid receptors (DOPrs) are being increasingly considered as promising alternatives. This review addresses DOPrs from the perspective of cellular and molecular determinants of their pharmacological diversity. Thus, DOPr ligands are examined in terms of structural and functional variety, DOPrs' capacity to engage a multiplicity of canonical and noncanonical G protein-dependent responses is surveyed, and evidence supporting ligand-specific signaling and regulation is analyzed. Pharmacological DOPr subtypes are examined in light of the ability of DOPr to organize into multimeric arrays and to adopt multiple active conformations as well as differences in ligand kinetics. Current knowledge on DOPr targeting to the membrane is examined as a means of understanding how these receptors are especially active in chronic pain management. Insight into cellular and molecular mechanisms of pharmacological diversity should guide the rational design of more effective, longer-lasting, and better-tolerated opioid analgesics for chronic pain management.
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Affiliation(s)
- Louis Gendron
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Catherine M Cahill
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Mark von Zastrow
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Peter W Schiller
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Graciela Pineyro
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
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13
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Villeneuve J, Duran J, Scarpa M, Bassaganyas L, Van Galen J, Malhotra V. Golgi enzymes do not cycle through the endoplasmic reticulum during protein secretion or mitosis. Mol Biol Cell 2016; 28:141-151. [PMID: 27807044 PMCID: PMC5221618 DOI: 10.1091/mbc.e16-08-0560] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 10/21/2016] [Accepted: 10/26/2016] [Indexed: 01/08/2023] Open
Abstract
The question of whether the Golgi complex is a stable compartment or is constantly regenerated from the endoplasmic reticulum (ER) is an important issue under debate. Using an ER trapping procedure and Golgi-specific O-linked glycosylation of a resident ER protein, this study demonstrates that Golgi enzymes do not cycle through the ER during secretion and mitosis. Golgi-specific sialyltransferase (ST) expressed as a chimera with the rapamycin-binding domain of mTOR, FRB, relocates to the endoplasmic reticulum (ER) in cells exposed to rapamycin that also express invariant chain (Ii)-FKBP in the ER. This result has been taken to indicate that Golgi-resident enzymes cycle to the ER constitutively. We show that ST-FRB is trapped in the ER even without Ii-FKBP upon rapamycin addition. This is because ER-Golgi–cycling FKBP proteins contain a C-terminal KDEL-like sequence, bind ST-FRB in the Golgi, and are transported together back to the ER by KDEL receptor–mediated retrograde transport. Moreover, depletion of KDEL receptor prevents trapping of ST-FRB in the ER by rapamycin. Thus ST-FRB cycles artificially by binding to FKBP domain–containing proteins. In addition, Golgi-specific O-linked glycosylation of a resident ER protein occurs only upon artificial fusion of Golgi membranes with ER. Together these findings support the consensus view that there is no appreciable mixing of Golgi-resident enzymes with ER under normal conditions.
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Affiliation(s)
- Julien Villeneuve
- Cell and Developmental Biology Department, Centre for Genomic Regulation, Barcelona Institute for Science and Technology, 08003 Barcelona, Spain.,Department of Molecular and Cell Biology and Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720
| | - Juan Duran
- Cell and Developmental Biology Department, Centre for Genomic Regulation, Barcelona Institute for Science and Technology, 08003 Barcelona, Spain.,Universitat Pompeu Fabra, 08002 Barcelona, Spain
| | - Margherita Scarpa
- Cell and Developmental Biology Department, Centre for Genomic Regulation, Barcelona Institute for Science and Technology, 08003 Barcelona, Spain
| | - Laia Bassaganyas
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94143.,Institute for Human Genetics, University of California, San Francisco, San Francisco, CA 94143
| | - Josse Van Galen
- Cell and Developmental Biology Department, Centre for Genomic Regulation, Barcelona Institute for Science and Technology, 08003 Barcelona, Spain
| | - Vivek Malhotra
- Cell and Developmental Biology Department, Centre for Genomic Regulation, Barcelona Institute for Science and Technology, 08003 Barcelona, Spain .,Universitat Pompeu Fabra, 08002 Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
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14
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Rämö O, Kumar D, Gucciardo E, Joensuu M, Saarekas M, Vihinen H, Belevich I, Smolander OP, Qian K, Auvinen P, Jokitalo E. NOGO-A/RTN4A and NOGO-B/RTN4B are simultaneously expressed in epithelial, fibroblast and neuronal cells and maintain ER morphology. Sci Rep 2016; 6:35969. [PMID: 27786289 PMCID: PMC5081510 DOI: 10.1038/srep35969] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 10/07/2016] [Indexed: 02/08/2023] Open
Abstract
Reticulons (RTNs) are a large family of membrane associated proteins with various functions. NOGO-A/RTN4A has a well-known function in limiting neurite outgrowth and restricting the plasticity of the mammalian central nervous system. On the other hand, Reticulon 4 proteins were shown to be involved in forming and maintaining endoplasmic reticulum (ER) tubules. Using comparative transcriptome analysis and qPCR, we show here that NOGO-B/RTN4B and NOGO-A/RTN4A are simultaneously expressed in cultured epithelial, fibroblast and neuronal cells. Electron tomography combined with immunolabelling reveal that both isoforms localize preferably to curved membranes on ER tubules and sheet edges. Morphological analysis of cells with manipulated levels of NOGO-B/RTN4B revealed that it is required for maintenance of normal ER shape; over-expression changes the sheet/tubule balance strongly towards tubules and causes the deformation of the cell shape while depletion of the protein induces formation of large peripheral ER sheets.
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Affiliation(s)
- Olli Rämö
- Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Darshan Kumar
- Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Erika Gucciardo
- Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Merja Joensuu
- Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Maiju Saarekas
- Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Helena Vihinen
- Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.,Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Ilya Belevich
- Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.,Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Olli-Pekka Smolander
- DNA Sequencing and Genomics Laboratory, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Kui Qian
- DNA Sequencing and Genomics Laboratory, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Petri Auvinen
- DNA Sequencing and Genomics Laboratory, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Eija Jokitalo
- Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.,Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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15
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Mitotic Golgi disassembly is required for bipolar spindle formation and mitotic progression. Proc Natl Acad Sci U S A 2016; 113:E6590-E6599. [PMID: 27791030 DOI: 10.1073/pnas.1610844113] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
During mitosis, the mammalian Golgi vesiculates and, upon partitioning, reassembles in each daughter cell; however, it is not clear whether the disassembly process per se is important for partitioning or is merely an outcome of mitotic entry. Here, we show that Golgi vesiculation is required for progression to metaphase. To prevent Golgi disassembly, we expressed HRP linked to a Golgi-resident protein and acutely triggered the polymerization of 3,3'-diaminobenzidine (DAB) in the Golgi lumen. The DAB polymer does not affect interphase cell viability, but inhibits Golgi fragmentation by nocodazole and brefeldin A and also halts cells in early mitosis. The arrest is Golgi specific and does not occur when DAB is polymerized in the endosomes. Cells with a DAB polymer in the Golgi enter mitosis normally but arrest with an intact Golgi clustered at a monopolar spindle and an active spindle assembly checkpoint (SAC). Mitotic progression is restored upon centrosome depletion by the Polo-like kinase 4 inhibitor, centrinone, indicating that the link between the Golgi and the centrosomes must be dissolved to reach metaphase. These results demonstrate that Golgi disassembly is required for mitotic progression because failure to vesiculate the Golgi activates the canonical SAC. This requirement suggests that cells actively monitor Golgi integrity in mitosis.
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16
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Ohsaki Y, Kawai T, Yoshikawa Y, Cheng J, Jokitalo E, Fujimoto T. PML isoform II plays a critical role in nuclear lipid droplet formation. J Cell Biol 2016; 212:29-38. [PMID: 26728854 PMCID: PMC4700481 DOI: 10.1083/jcb.201507122] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PML-II plays a critical role in generating nuclear lipid droplets, which are associated with promyelocytic leukemia nuclear bodies as well as with the extension of the inner nuclear membrane. Lipid droplets (LDs) in the nucleus of hepatocyte-derived cell lines were found to be associated with premyelocytic leukemia (PML) nuclear bodies (NBs) and type I nucleoplasmic reticulum (NR) or the extension of the inner nuclear membrane. Knockdown of PML isoform II (PML-II) caused a significant decrease in both nuclear LDs and type I NR, whereas overexpression of PML-II increased both. Notably, these effects were evident only in limited types of cells, in which a moderate number of nuclear LDs exist intrinsically, and PML-II was targeted not only at PML NBs, but also at the nuclear envelope, excluding lamins and SUN proteins. Knockdown of SUN proteins induced a significant increase in the type I NR and nuclear LDs, but these effects were cancelled by simultaneous knockdown of PML-II. Nuclear LDs harbored diacylglycerol O-acyltransferase 2 and CTP:phosphocholine cytidylyltransferase α and incorporated newly synthesized lipid esters. These results corroborated that PML-II plays a critical role in generating nuclear LDs in specific cell types.
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Affiliation(s)
- Yuki Ohsaki
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Takeshi Kawai
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Yukichika Yoshikawa
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Jinglei Cheng
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Eija Jokitalo
- Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Toyoshi Fujimoto
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
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17
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ER trapping reveals Golgi enzymes continually revisit the ER through a recycling pathway that controls Golgi organization. Proc Natl Acad Sci U S A 2015; 112:E6752-61. [PMID: 26598700 DOI: 10.1073/pnas.1520957112] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Whether Golgi enzymes remain localized within the Golgi or constitutively cycle through the endoplasmic reticulum (ER) is unclear, yet is important for understanding Golgi dependence on the ER. Here, we demonstrate that the previously reported inefficient ER trapping of Golgi enzymes in a rapamycin-based assay results from an artifact involving an endogenous ER-localized 13-kD FK506 binding protein (FKBP13) competing with the FKBP12-tagged Golgi enzyme for binding to an FKBP-rapamycin binding domain (FRB)-tagged ER trap. When we express an FKBP12-tagged ER trap and FRB-tagged Golgi enzymes, conditions precluding such competition, the Golgi enzymes completely redistribute to the ER upon rapamycin treatment. A photoactivatable FRB-Golgi enzyme, highlighted only in the Golgi, likewise redistributes to the ER. These data establish Golgi enzymes constitutively cycle through the ER. Using our trapping scheme, we identify roles of rab6a and calcium-independent phospholipase A2 (iPLA2) in Golgi enzyme recycling, and show that retrograde transport of Golgi membrane underlies Golgi dispersal during microtubule depolymerization and mitosis.
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18
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Wei JH, Zhang ZC, Wynn RM, Seemann J. GM130 Regulates Golgi-Derived Spindle Assembly by Activating TPX2 and Capturing Microtubules. Cell 2015; 162:287-299. [PMID: 26165940 DOI: 10.1016/j.cell.2015.06.014] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 02/16/2015] [Accepted: 05/18/2015] [Indexed: 11/16/2022]
Abstract
Spindle assembly requires the coordinated action of multiple cellular structures to nucleate and organize microtubules in a precise spatiotemporal manner. Among them, the contributions of centrosomes, chromosomes, and microtubules have been well studied, yet the involvement of membrane-bound organelles remains largely elusive. Here, we provide mechanistic evidence for a membrane-based, Golgi-derived microtubule assembly pathway in mitosis. Upon mitotic entry, the Golgi matrix protein GM130 interacts with importin α via a classical nuclear localization signal that recruits importin α to the Golgi membranes. Sequestration of importin α by GM130 liberates the spindle assembly factor TPX2, which activates Aurora-A kinase and stimulates local microtubule nucleation. Upon filament assembly, nascent microtubules are further captured by GM130, thus linking Golgi membranes to the spindle. Our results reveal an active role for the Golgi in regulating spindle formation to ensure faithful organelle inheritance.
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Affiliation(s)
- Jen-Hsuan Wei
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Zi Chao Zhang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - R Max Wynn
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Joachim Seemann
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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19
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Dopie J, Rajakylä EK, Joensuu MS, Huet G, Ferrantelli E, Xie T, Jäälinoja H, Jokitalo E, Vartiainen MK. Genome-wide RNAi screen for nuclear actin reveals a network of cofilin regulators. J Cell Sci 2015; 128:2388-400. [PMID: 26021350 PMCID: PMC4510847 DOI: 10.1242/jcs.169441] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 05/19/2015] [Indexed: 01/15/2023] Open
Abstract
Nuclear actin plays an important role in many processes that regulate gene expression. Cytoplasmic actin dynamics are tightly controlled by numerous actin-binding proteins, but regulation of nuclear actin has remained unclear. Here, we performed a genome-wide RNA interference (RNAi) screen in Drosophila cells to identify proteins that influence either nuclear polymerization or import of actin. We validate 19 factors as specific hits, and show that Chinmo (known as Bach2 in mammals), SNF4Aγ (Prkag1 in mammals) and Rab18 play a role in nuclear localization of actin in both fly and mammalian cells. We identify several new regulators of cofilin activity, and characterize modulators of both cofilin kinases and phosphatase. For example, Chinmo/Bach2, which regulates nuclear actin levels also in vivo, maintains active cofilin by repressing the expression of the kinase Cdi (Tesk in mammals). Finally, we show that Nup98 and lamin are candidates for regulating nuclear actin polymerization. Our screen therefore reveals new aspects of actin regulation and links nuclear actin to many cellular processes.
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Affiliation(s)
- Joseph Dopie
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Eeva K Rajakylä
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Merja S Joensuu
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Guillaume Huet
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Evelina Ferrantelli
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Tiao Xie
- Image and Data Analysis Core (IDAC), Harvard Medical School, Boston, MA 02115, USA
| | - Harri Jäälinoja
- Light Microscopy Unit, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Eija Jokitalo
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Maria K Vartiainen
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
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20
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Schuberth CE, Tängemo C, Coneva C, Tischer C, Pepperkok R. Self-organization of core Golgi material is independent of COPII-mediated endoplasmic reticulum export. J Cell Sci 2015; 128:1279-93. [PMID: 25717003 DOI: 10.1242/jcs.154443] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The Golgi is a highly organized and dynamic organelle that receives and distributes material from and to the endoplasmic reticulum (ER) and the endocytic pathway. One open question about Golgi organization is whether it is solely based on ER-to-Golgi transport. Here, we analyzed the kinetics of Golgi breakdown in the absence of COPII-dependent ER export with high temporal and spatial resolution using quantitative fluorescence microscopy. We found that Golgi breakdown occurred in two phases. While Golgi enzymes continuously redistributed to the ER, we consistently observed extensive Golgi fragmentation at the beginning of the breakdown, followed by microtubule-dependent formation of a Golgi remnant structure (phase 1). Further Golgi disintegration occurred less uniformly (phase 2). Remarkably, cisternal Golgi morphology was lost early in phase 1 and Golgi fragments instead corresponded to variably sized vesicle clusters. These breakdown intermediates were devoid of COPI-dependent recycling material, but contained typical 'core' Golgi components. Furthermore, Golgi breakdown intermediates were able to disassemble and reassemble following cell division, indicating that they retained important regulatory capabilities. Taken together, these findings support the view that Golgi self-organization exists independently of ER-to-Golgi transport.
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Affiliation(s)
- Christian E Schuberth
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany Institute of Cell Dynamics and Imaging, University of Muenster, von-Esmarch-Str. 56, 48149 Muenster, Germany Cells in Motion Cluster of Excellence (EXC1003-CiM), University of Muenster, von-Esmarch-Str. 56, 48149 Muenster, Germany
| | - Carolina Tängemo
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Cvetalina Coneva
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Christian Tischer
- Advanced Light Microscopy Facility, European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Rainer Pepperkok
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany Advanced Light Microscopy Facility, European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany
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21
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Jongsma MLM, Berlin I, Neefjes J. On the move: organelle dynamics during mitosis. Trends Cell Biol 2014; 25:112-24. [PMID: 25466831 DOI: 10.1016/j.tcb.2014.10.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 10/23/2014] [Accepted: 10/28/2014] [Indexed: 10/24/2022]
Abstract
A cell constitutes the minimal self-replicating unit of all organisms, programmed to propagate its genome as it proceeds through mitotic cell division. The molecular processes entrusted with ensuring high fidelity of DNA replication and subsequent segregation of chromosomes between daughter cells have therefore been studied extensively. However, to process the information encoded in its genome a cell must also pass on its non-genomic identity to future generations. To achieve productive sharing of intracellular organelles, cells have evolved complex mechanisms of organelle inheritance. Many membranous compartments undergo vast spatiotemporal rearrangements throughout mitosis. These controlled organizational changes are crucial to enabling completion of the division cycle and ensuring successful progeny. Herein we review current understanding of intracellular organelle segregation during mitotic division in mammalian cells, with a focus on compartment organization and integrity throughout the inheritance process.
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Affiliation(s)
- Marlieke L M Jongsma
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Ilana Berlin
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Jacques Neefjes
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
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22
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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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23
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Marie M, Dale HA, Kouprina N, Saraste J. Division of the intermediate compartment at the onset of mitosis provides a mechanism for Golgi inheritance. J Cell Sci 2012; 125:5403-16. [PMID: 22946056 DOI: 10.1242/jcs.108100] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
As mammalian cells prepare for mitosis, the Golgi ribbon is first unlinked into its constituent stacks and then transformed into spindle-associated, pleiomorphic membrane clusters in a process that remains enigmatic. Also, it remains unclear whether Golgi inheritance involves the incorporation of Golgi enzymes into a pool of coat protein I (COPI) vesicles, or their COPI-independent transfer to the endoplasmic reticulum (ER). Based on the observation that the intermediate compartment (IC) at the ER-Golgi boundary is connected to the centrosome, we examined its mitotic fate and possible role in Golgi breakdown. The use of multiple imaging techniques and markers revealed that the IC elements persist during the M phase, maintain their compositional and structural properties and remain associated with the mitotic spindle, forming circular arrays at the spindle poles. At G2/M transition, the movement of the pericentrosomal domain of the IC (pcIC) to the cell centre and its expansion coincide with the unlinking of the Golgi ribbon. At prophase, coupled to centrosome separation, the pcIC divides together with recycling endosomes, providing novel landmarks for mitotic entry. We provide evidence that the permanent IC elements function as way stations during the COPI-dependent dispersal of Golgi components at prometa- and metaphase, indicating that they correspond to the previously described Golgi clusters. In addition, they continue to communicate with the vesicular 'Golgi haze' and thus are likely to provide templates for Golgi reassembly. These results implicate the IC in mitotic Golgi inheritance, resulting in a model that integrates key features of the two previously proposed pathways.
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Affiliation(s)
- Michaël Marie
- Department of Biomedicine and Molecular Imaging Center, University of Bergen, Jonas Lies Vei 91, N-5009 Bergen, Norway
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24
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Puhka M, Joensuu M, Vihinen H, Belevich I, Jokitalo E. Progressive sheet-to-tubule transformation is a general mechanism for endoplasmic reticulum partitioning in dividing mammalian cells. Mol Biol Cell 2012; 23:2424-32. [PMID: 22573885 PMCID: PMC3386207 DOI: 10.1091/mbc.e10-12-0950] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During mitosis, ER network reorganization can lead to packing of the ER into tight concentric layers at the cell cortex and occurs in tandem with rounding of the cell. Morphometric and 3D EM analysis shows that in addition to reorganization, ER sheets undergo transformation toward more fenestrated and tubular forms before anaphase in mammalian cells. The endoplasmic reticulum (ER) is both structurally and functionally complex, consisting of a dynamic network of interconnected sheets and tubules. To achieve a more comprehensive view of ER organization in interphase and mitotic cells and to address a discrepancy in the field (i.e., whether ER sheets persist, or are transformed to tubules, during mitosis), we analyzed the ER in four different mammalian cell lines using live-cell imaging, high-resolution electron microscopy, and three dimensional electron microscopy. In interphase cells, we found great variation in network organization and sheet structures among different cell lines. In mitotic cells, we show that the ER undergoes both spatial reorganization and structural transformation of sheets toward more fenestrated and tubular forms. However, the extent of spatial reorganization and sheet-to-tubule transformation varies among cell lines. Fenestration and tubulation of the ER correlates with a reduced number of membrane-bound ribosomes.
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Affiliation(s)
- Maija Puhka
- Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
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25
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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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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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Aronson DE, Costantini LM, Snapp EL. Superfolder GFP is fluorescent in oxidizing environments when targeted via the Sec translocon. Traffic 2011; 12:543-8. [PMID: 21255213 DOI: 10.1111/j.1600-0854.2011.01168.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The ability to study proteins in live cells using genetically encoded fluorescent proteins (FPs) has revolutionized cell biology (1-3). Researchers have created numerous FP biosensors and optimized FPs for specific organisms and subcellular environments in a rainbow of colors (4,5). However, expressing FPs in oxidizing environments such as the eukaryotic endoplasmic reticulum (ER) or the bacterial periplasm can impair folding, thereby preventing fluorescence (6,7). A substantial fraction of enhanced green fluorescent protein (EGFP) oligomerizes to form non-fluorescent mixed disulfides in the ER (6) and EGFP does not fluoresce in the periplasm when targeted via the SecYEG translocon (7). To overcome these obstacles, we exploited the highly efficient folding capability of superfolder GFP (sfGFP) (8). Here, we report sfGFP does not form disulfide-linked oligomers in the ER and maltose-binding protein (MBP) signal sequence (peri)-sfGFP (9) is brightly fluorescent in the periplasm of Escherichia coli. Thus, sfGFP represents an important research tool for studying resident proteins of oxidizing environments.
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Affiliation(s)
- Deborah E Aronson
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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28
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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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29
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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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Emr S, Glick BS, Linstedt AD, Lippincott-Schwartz J, Luini A, Malhotra V, Marsh BJ, Nakano A, Pfeffer SR, Rabouille C, Rothman JE, Warren G, Wieland FT. Journeys through the Golgi--taking stock in a new era. ACTA ACUST UNITED AC 2009; 187:449-53. [PMID: 19948493 PMCID: PMC2779233 DOI: 10.1083/jcb.200909011] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Golgi apparatus is essential for protein sorting and transport. Many researchers have long been fascinated with the form and function of this organelle. Yet, despite decades of scrutiny, the mechanisms by which proteins are transported across the Golgi remain controversial. At a recent meeting, many prominent Golgi researchers assembled to critically evaluate the core issues in the field. This report presents the outcome of their discussions and highlights the key open questions that will help guide the field into a new era.
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Affiliation(s)
- Scott Emr
- Department of Cell and Developmental Biology, CRG-Centre de Regulació Genòmica, Institutcio Catalana de Recerca I Estudis Avancats, 88 08003 Barcelona, Spain
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31
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Wei JH, Seemann J. Induction of asymmetrical cell division to analyze spindle-dependent organelle partitioning using correlative microscopy techniques. Nat Protoc 2009; 4:1653-62. [PMID: 19876022 DOI: 10.1038/nprot.2009.160] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This protocol describes an assay for the induction of asymmetrical cell division where the entire spindle is segregated into only one of the daughter cells. The procedure consists of four stages: (i) generation of asymmetrical monoasters by arresting cells in early mitosis with a kinesin Eg5 inhibitor; (ii) induction of cell division by microinjection of recombinant Mad1 protein or by the addition of a Cdk1 inhibitor; (iii) monitoring the division process by phase-contrast time-lapse microscopy; and (iv) processing for correlative immunofluorescence or correlative electron microscopy. This approach can be applied to determine the requirement for the mitotic spindle in organelle partitioning as well as to investigate the role of the monopolar spindle in cytokinesis. Moreover, the generated nucleus-lacking cytoplast provides an ideal environment to test the feasibility and activity of biological processes in the absence of genomic influence. The protocol takes 2-4 d to complete.
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Affiliation(s)
- Jen-Hsuan Wei
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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32
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Hölzenspies JJ, Stoorvogel W, Colenbrander B, Roelen BAJ, Gutknecht DR, van Haeften T. CDC2/SPDY transiently associates with endoplasmic reticulum exit sites during oocyte maturation. BMC DEVELOPMENTAL BIOLOGY 2009; 9:8. [PMID: 19187565 PMCID: PMC2644288 DOI: 10.1186/1471-213x-9-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Accepted: 02/03/2009] [Indexed: 11/10/2022]
Abstract
BACKGROUND Mammalian oocytes acquire competence to be fertilized during meiotic maturation. The protein kinase CDC2 plays a pivotal role in several key maturation events, in part through controlled changes in CDC2 localization. Although CDC2 is involved in initiation of maturation, a detailed analysis of CDC2 localization at the onset of maturation is lacking. In this study, the subcellular distribution of CDC2 and its regulatory proteins cyclin B and SPDY in combination with several organelle markers at the onset of pig oocyte maturation has been investigated. RESULTS Our results demonstrate that CDC2 transiently associates with a single domain, identified as a cluster of endoplasmic reticulum (ER) exit sites (ERES) by the presence of SEC23, in the cortex of maturing porcine oocytes prior to germinal vesicle break down. Inhibition of meiosis resumption by forskolin treatment prevented translocation of CDC2 to this ERES cluster. Phosphorylated GM130 (P-GM130), which is a marker for fragmented Golgi, localized to ERES in almost all immature oocytes and was not affected by forskolin treatment. After removal of forskolin from the culture media, the transient translocation of CDC2 to ERES was accompanied by a transient dispersion of P-GM130 into the ER suggesting a role for CDC2 in redistributing Golgi components that have collapsed into ERES further into the ER during meiosis. Finally, we show that SPDY, rather than cyclin B, colocalizes with CDC2 at ERES, suggesting a role for the CDC2/SPDY complex in regulating the secretory pathway during oocyte maturation. CONCLUSION Our data demonstrate the presence of a novel structure in the cortex of porcine oocytes that comprises ERES and transiently accumulates CDC2 prior to germinal vesicle breakdown. In addition, we show that SPDY, but not cyclin B, localizes to this ERES cluster together with CDC2.
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Affiliation(s)
- Jurriaan J Hölzenspies
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
- Department of Biochemistry & Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Willem Stoorvogel
- Department of Biochemistry & Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Ben Colenbrander
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Bernard AJ Roelen
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Dagmar R Gutknecht
- Department of Reproductive Medicine, University Medical Centre, Utrecht, the Netherlands
| | - Theo van Haeften
- Department of Biochemistry & Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
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33
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Abstract
The mammalian Golgi ribbon disassembles during mitosis and reforms in both daughter cells after division. Mitotic Golgi membranes concentrate around the spindle poles, suggesting that the spindle may control Golgi partitioning. To test this, cells were induced to divide asymmetrically with the entire spindle segregated into only one daughter cell. A ribbon reforms in the nucleated karyoplasts, whereas the Golgi stacks in the cytoplasts are scattered. However, the scattered Golgi stacks are polarized and transport cargo. Microinjection of Golgi extract together with tubulin or incorporation of spindle materials rescues Golgi ribbon formation. Therefore, the factors required for postmitotic Golgi ribbon assembly are transferred by the spindle, but the constituents of functional stacks are partitioned independently, suggesting that Golgi inheritance is regulated by two distinct mechanisms.
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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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34
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Abstract
The interface between the endoplasmic reticulum (ER) and the Golgi apparatus is a critical junction in the secretory pathway mediating the transport of both soluble and membrane cargo between the two organelles. Such transport can be bidirectional and is mediated by coated membranes. In this review, we consider the organization and dynamics of this interface in plant cells, the putative structure of which has caused some controversy in the literature, and we speculate on the stages of Golgi biogenesis from the ER and the role of the Golgi and ER on each other's motility.
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Affiliation(s)
- Chris Hawes
- School of Life Sciences, Oxford Brookes University, Headington, Oxford, UK.
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35
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The role of cell differentiation in controlling cell multiplication and cancer. J Cancer Res Clin Oncol 2008; 134:725-41. [DOI: 10.1007/s00432-008-0381-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2007] [Accepted: 03/17/2008] [Indexed: 10/22/2022]
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36
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Bartz R, Sun LP, Bisel B, Wei JH, Seemann J. Spatial separation of Golgi and ER during mitosis protects SREBP from unregulated activation. EMBO J 2008; 27:948-55. [PMID: 18323777 DOI: 10.1038/emboj.2008.36] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Accepted: 02/13/2008] [Indexed: 12/28/2022] Open
Abstract
Sterol regulatory element-binding proteins (SREBPs) are membrane-bound transcription factors that reside as inactive precursors in the endoplasmic reticulum (ER) membrane. After sterol depletion, the proteins are transported to the Golgi apparatus, where they are cleaved by site-1 protease (S1P). Cleavage releases the active transcription factors, which then enter the nucleus to induce genes that regulate cellular levels of cholesterol and phospholipids. This regulation depends on the spatial separation of the Golgi and the ER, as mixing of the compartments induces unregulated activation of SREBPs. Here, we show that S1P is localized to the Golgi, but cycles continuously through the ER and becomes trapped when ER exit is inhibited. During mitosis, S1P is associated with mitotic Golgi clusters, which remain distinct from the ER. In mitotic cells, S1P is active, but SREBP is not cleaved as S1P and SREBP reside in different compartments. Together, these results indicate that the spatial separation of the Golgi and the ER is maintained during mitosis, which is essential to protect the S1P substrate SREBP from unregulated activation during mitosis.
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Affiliation(s)
- René Bartz
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039, USA
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37
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Puhka M, Vihinen H, Joensuu M, Jokitalo E. Endoplasmic reticulum remains continuous and undergoes sheet-to-tubule transformation during cell division in mammalian cells. ACTA ACUST UNITED AC 2007; 179:895-909. [PMID: 18056408 PMCID: PMC2099207 DOI: 10.1083/jcb.200705112] [Citation(s) in RCA: 182] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The endoplasmic reticulum (ER) is a multifaceted cellular organelle both structurally and functionally, and its cell cycle–dependent morphological changes are poorly understood. Our quantitative confocal and EM analyses show that the ER undergoes dramatic reorganization during cell division in cultured mammalian cells as mitotic ER profiles become shorter and more branched. 3D modeling by electron tomography reveals that the abundant interphase structures, sheets, are lost and subsequently transform into a branched tubular network that remains continuous. This is confirmed by observing the most prominent ER subdomain, the nuclear envelope (NE). A NE marker protein spreads to the mitotic ER tubules, although it does not show a homogenous distribution within the network. We mimicked the mitotic ER reorganization using puromycin to strip the membrane-bound ribosomes from the interphase ER corresponding to the observed loss of ribosomes normally occurring during mitosis. We propose that the structural changes in mitotic ER are linked to ribosomal action on the ER membranes.
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Affiliation(s)
- Maija Puhka
- Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
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38
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Jollivet F, Raposo G, Dimitrov A, Sougrat R, Goud B, Perez F. Analysis of de novo Golgi complex formation after enzyme-based inactivation. Mol Biol Cell 2007; 18:4637-47. [PMID: 17855505 PMCID: PMC2043539 DOI: 10.1091/mbc.e07-08-0799] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The Golgi complex is characterized by its unique morphology of closely apposed flattened cisternae that persists despite the large quantity of lipids and proteins that transit bidirectionally. Whether such a structure is maintained through endoplasmic reticulum (ER)-based recycling and auto-organization or whether it depends on a permanent Golgi structure is strongly debated. To further study Golgi maintenance in interphase cells, we developed a method allowing for a drug-free inactivation of Golgi dynamics and function in living cells. After Golgi inactivation, a new Golgi-like structure, containing only certain Golgi markers and newly synthesized cargoes, was produced. However, this structure did not acquire a normal Golgi architecture and was unable to ensure a normal trafficking activity. This suggests an integrative model for Golgi maintenance in interphase where the ER is able to autonomously produce Golgi-like structures that need pre-existing Golgi complexes to be organized as morphologically normal and active Golgi elements.
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Affiliation(s)
- Florence Jollivet
- *Centre National de la Recherche Scientifique Unité Mixte de Recherche 144, 75248 Paris Cedex 05, France
- Institut Curie, 75248 Paris Cedex 05, France; and
| | - Graça Raposo
- *Centre National de la Recherche Scientifique Unité Mixte de Recherche 144, 75248 Paris Cedex 05, France
- Institut Curie, 75248 Paris Cedex 05, France; and
| | - Ariane Dimitrov
- *Centre National de la Recherche Scientifique Unité Mixte de Recherche 144, 75248 Paris Cedex 05, France
- Institut Curie, 75248 Paris Cedex 05, France; and
| | - Rachid Sougrat
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-5430
| | - Bruno Goud
- *Centre National de la Recherche Scientifique Unité Mixte de Recherche 144, 75248 Paris Cedex 05, France
- Institut Curie, 75248 Paris Cedex 05, France; and
| | - Franck Perez
- *Centre National de la Recherche Scientifique Unité Mixte de Recherche 144, 75248 Paris Cedex 05, France
- Institut Curie, 75248 Paris Cedex 05, France; and
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Lowe M, Barr FA. Inheritance and biogenesis of organelles in the secretory pathway. Nat Rev Mol Cell Biol 2007; 8:429-39. [PMID: 17505521 DOI: 10.1038/nrm2179] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In eukaryotic cells, cellular functions are compartmentalized into membrane-bound organelles. This has many advantages, as shown by the success of the eukaryotic lineage, but creates many problems for cells, such as the need to build and partition these organelles during cell growth and division. Diverse mechanisms for biogenesis of the endoplasmic reticulum and Golgi apparatus have evolved, ranging from de novo synthesis to the copying of a template organelle. The different mechanisms by which organelles are inherited in yeasts, protozoa and metazoans probably reflect the differences in the structure and copy number of these organelles.
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Affiliation(s)
- Martin Lowe
- Faculty of Life Sciences, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
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40
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Zitnik G, Wang L, Martin GM, Hu Q. Localizations of endogenous APP/APP-proteolytic products are consistent with microtubular transport. J Mol Neurosci 2007; 31:59-68. [PMID: 17416970 DOI: 10.1007/bf02686118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 11/30/1999] [Accepted: 06/03/2006] [Indexed: 12/12/2022]
Abstract
Dementia of the Alzheimer type (DAT) is associated with the accumulation of beta-amyloid (A beta) peptides derived from beta-amyloid precursor protein (APP). Goldstein and coworkers have suggested that APP acts as a cargo receptor connecting post-Golgi vesicles and motor proteins. Sisodia and colleagues have suggested that APP is a passive passenger within the vesicles. Both views predict that one should be able to visualize colocalizations of APP with microtubules, the object of the present investigation. To avoid possible artifacts created by APP overexpression, we studied endogenous expression in a human neuroblastoma cell line (SK-N-SH). Using high resolution fluorescence microscopy and antibodies specific for the amino termini of APP and A beta sequences, we found that endogenous APP and A beta peptide immunoreactivities colocalized with microtubules in interphase cells. Disruption of microtubules, followed by fixation at various time points during repolymerization, allowed us to observe the sequence and timing of these colocalizations in interphase cells. In addition, to our surprise, we found that A beta immunoreactivities colocalize with the mitotic spindle, a bundle of specialized microtubules. Because of the condensed cytoplasm found in neurons, we suggest that SK-N-SH cells might be a more convenient experimental system for exploring the mechanisms that underlie these protein localizations and the pathology that might result from altered APP protein structure and function.
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Affiliation(s)
- Galynn Zitnik
- Department of Pathology, University of Washington, Seattle, WA 98195-7470, USA.
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41
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Lin X, Liu CC, Gao Q, Zhang X, Wu G, Lee WH. RINT-1 serves as a tumor suppressor and maintains Golgi dynamics and centrosome integrity for cell survival. Mol Cell Biol 2007; 27:4905-16. [PMID: 17470549 PMCID: PMC1951495 DOI: 10.1128/mcb.02396-06] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Faithful mitotic partitioning of the Golgi apparatus and the centrosome is critical for proper cell division. Although these two cytoplasmic organelles are probably coordinated during cell division, supporting evidence of this coordination is still largely lacking. Here, we show that the RAD50-interacting protein, RINT-1, is localized at the Golgi apparatus and the centrosome in addition to the endoplasmic reticulum. To examine the biological roles of RINT-1, we found that the homozygous deletion of Rint-1 caused early embryonic lethality at embryonic day 5 (E5) to E6 and the failure of blastocyst outgrowth ex vivo. About 81% of the Rint-1 heterozygotes succumbed to multiple tumor formation with haploinsufficiency during their average life span of 24 months. To pinpoint the cellular function of RINT-1, we found that RINT-1 depletion by RNA interference led to the loss of the pericentriolar positioning and dispersal of the Golgi apparatus and concurrent centrosome amplification during the interphase. Upon mitotic entry, RINT-1-deficient cells exhibited multiple abnormalities, including aberrant Golgi dynamics during early mitosis and defective reassembly at telophase, increased formation of multiple spindle poles, and frequent chromosome missegregation. Mitotic cells often underwent cell death in part due to the overwhelming cellular defects. Taken together, these findings suggest that RINT-1 serves as a novel tumor suppressor essential for maintaining the dynamic integrity of the Golgi apparatus and the centrosome, a prerequisite to their proper coordination during cell division.
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Affiliation(s)
- Xiaoqin Lin
- Department of Biological Chemistry, 124 Sprague Hall, 839 Medical Science Ct., University of California, Irvine, Irvine, CA 92697, USA
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42
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Gniadek TJ, Warren G. WatershedCounting3D: A New Method for Segmenting and Counting Punctate Structures from Confocal Image Data. Traffic 2007; 8:339-46. [PMID: 17319897 DOI: 10.1111/j.1600-0854.2007.00538.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Current research in cell biology frequently uses light microscopy to study intracellular organelles. To segment and count organelles, most investigators have used a global thresholding method, which relies on homogeneous background intensity values within a cell. Because this is not always the case, we developed WatershedCounting3D, a program that uses a modified watershed algorithm to more accurately identify intracellular structures from confocal image data, even in the presence of an inhomogeneous background. We give examples of segmenting and counting endoplasmic reticulum exit sites and the Golgi apparatus.
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Affiliation(s)
- Thomas J Gniadek
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, PO Box 208002, New Haven, CT 06520-8002, USA.
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43
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Gaietta GM, Giepmans BNG, Deerinck TJ, Smith WB, Ngan L, Llopis J, Adams SR, Tsien RY, Ellisman MH. Golgi twins in late mitosis revealed by genetically encoded tags for live cell imaging and correlated electron microscopy. Proc Natl Acad Sci U S A 2006; 103:17777-82. [PMID: 17101980 PMCID: PMC1635977 DOI: 10.1073/pnas.0608509103] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Combinations of molecular tags visible in light and electron microscopes become particularly advantageous in the analysis of dynamic cellular components like the Golgi apparatus. This organelle disassembles at the onset of mitosis and, after a sequence of poorly understood events, reassembles after cytokinesis. The precise location of Golgi membranes and resident proteins during mitosis remains unclear, partly due to limitations of molecular markers and the resolution of light microscopy. We generated a fusion consisting of the first 117 residues of alpha-mannosidase II tagged with a fluorescent protein and a tetracysteine motif. The mannosidase component guarantees docking into the Golgi membrane, with the tags exposed in the lumen. The fluorescent protein is optically visible without further treatment, whereas the tetracysteine tag can be reduced acutely with a membrane-permeant phosphine, labeled with ReAsH, monitored in the light microscope, and used to trigger the photoconversion of diaminobenzidine, allowing 4D optical recording on live cells and correlated ultrastructural analysis by electron microscopy. These methods reveal that Golgi reassembly is preceded by the formation of four colinear clusters at telophase, two per daughter cell. Within each daughter, the smaller cluster near the midbody gradually migrates to rejoin the major cluster on the far side of the nucleus and asymmetrically reconstitutes a single Golgi apparatus, first in one daughter cell and then in the other. Our studies provide previously undescribed insights into Golgi disassociation and reassembly during mitosis and offer a powerful approach to follow recombinant protein distribution in 4D imaging and correlated high-resolution analysis.
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Affiliation(s)
- Guido M. Gaietta
- *National Center for Microscopy and Imaging Research, Center for Research on Biological Structure, and
| | - Ben N. G. Giepmans
- *National Center for Microscopy and Imaging Research, Center for Research on Biological Structure, and
- Department of Pharmacology and
| | - Thomas J. Deerinck
- *National Center for Microscopy and Imaging Research, Center for Research on Biological Structure, and
| | - W. Bryan Smith
- *National Center for Microscopy and Imaging Research, Center for Research on Biological Structure, and
| | - Lucy Ngan
- *National Center for Microscopy and Imaging Research, Center for Research on Biological Structure, and
| | - Juan Llopis
- Facultad de Medicina y Centro Regional de Investigaciones Biomédicas, Universidad de Castilla-La Mancha, C/Almansa s/n, 02006 Albacete, Spain
| | | | - Roger Y. Tsien
- Department of Pharmacology and
- Howard Hughes Medical Institute, Department Code 0648, University of California at San Diego, La Jolla, CA 92093; and
- To whom correspondence should be addressed. E-mail:
| | - Mark H. Ellisman
- *National Center for Microscopy and Imaging Research, Center for Research on Biological Structure, and
- Department of Neurosciences, Department Code 0608, University of California at San Diego, La Jolla, CA 92093
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44
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Radulescu AE, Siddhanta A, Shields D. A role for clathrin in reassembly of the Golgi apparatus. Mol Biol Cell 2006; 18:94-105. [PMID: 17065556 PMCID: PMC1751329 DOI: 10.1091/mbc.e06-06-0532] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The Golgi apparatus is a highly dynamic organelle whose organization is maintained by a proteinaceous matrix, cytoskeletal components, and inositol phospholipids. In mammalian cells, disassembly of the organelle occurs reversibly at the onset of mitosis and irreversibly during apoptosis. Several pharmacological agents including nocodazole, brefeldin A (BFA), and primary alcohols (1-butanol) induce reversible fragmentation of the Golgi apparatus. To dissect the mechanism of Golgi reassembly, rat NRK and GH3 cells were treated with 1-butanol, BFA, or nocodazole. During washout of 1-butanol, clathrin, a ubiquitous coat protein implicated in vesicle traffic at the trans-Golgi network and plasma membrane, and abundant clathrin coated vesicles were recruited to the region of nascent Golgi cisternae. Knockdown of endogenous clathrin heavy chain showed that the Golgi apparatus failed to reform efficiently after BFA or 1-butanol removal. Instead, upon 1-butanol washout, it maintained a compact, tight morphology. Our results suggest that clathrin is required to reassemble fragmented Golgi elements. In addition, we show that after butanol treatment the Golgi apparatus reforms via an initial compact intermediate structure that is subsequently remodeled into the characteristic interphase lace-like morphology and that reassembly requires clathrin.
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Affiliation(s)
| | | | - Dennis Shields
- *Departments of Developmental and Molecular Biology and
- Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461
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45
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Eisman RC, Stewart N, Miller D, Kaufman TC. centrosomin's beautiful sister (cbs) encodes a GRIP-domain protein that marks Golgi inheritance and functions in the centrosome cycle in Drosophila. J Cell Sci 2006; 119:3399-412. [PMID: 16882688 DOI: 10.1242/jcs.03088] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanism of inheritance of the Golgi complex is an important problem in cell biology. In this study, we examine the localization and function of a Golgi protein encoded by centrosomin's beautiful sister (cbs) during cleavage in Drosophila melanogaster. Cbs contains a GRIP domain that is 57% identical to vertebrate Golgin-97. Cbs undergoes a dramatic relocalization during mitosis from the cytoplasm to an association with chromosomes from late prometaphase to early telophase, by a transport mechanism that requires the GRIP domain and Arl1, the product of the Arf72A locus. Additionally, Cbs remains independent of the endoplasmic reticulum throughout cleavage. The use of RNAi, Arf72A mutant analysis and ectopic expression of the GRIP domain, shows that cycling of Cbs during mitosis is required for the centrosome cycle. The effects on the centrosome cycle depend on Cbs concentration and Cbs transport from the cytoplasm to DNA. When Cbs levels are reduced centrosomes fail to mature, and when Cbs transport is impeded by ectopic expression of the GRIP domain, centrosomes undergo hypertrophy. We propose that, Cbs is a trans-Golgi protein that links Golgi inheritance to the cell cycle and the Drosophila Golgi is more vertebrate-like than previously recognized.
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Affiliation(s)
- Robert C Eisman
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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46
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Jiang S, Rhee SW, Gleeson PA, Storrie B. Capacity of the Golgi apparatus for cargo transport prior to complete assembly. Mol Biol Cell 2006; 17:4105-17. [PMID: 16837554 PMCID: PMC1556386 DOI: 10.1091/mbc.e05-12-1112] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In yeast, particular emphasis has been given to endoplasmic reticulum (ER)-derived, cisternal maturation models of Golgi assembly while in mammalian cells more emphasis has been given to golgins as a potentially stable assembly framework. In the case of de novo Golgi formation from the ER after brefeldin A/H89 washout in HeLa cells, we found that scattered, golgin-enriched, structures formed early and contained golgins including giantin, ranging across the entire cis to trans spectrum of the Golgi apparatus. These structures were incompetent in VSV-G cargo transport. Second, we compared Golgi competence in cargo transport to the kinetics of addition of various glycosyltransferases and glycosidases into nascent, golgin-enriched structures after drug washout. Enzyme accumulation was sequential with trans and then medial glycosyltransferases/glycosidases found in the scattered, nascent Golgi. Involvement in cargo transport preceded full accumulation of enzymes or GPP130 into nascent Golgi. Third, during mitosis, we found that the formation of a golgin-positive acceptor compartment in early telophase preceded the accumulation of a Golgi glycosyltransferase in nascent Golgi structures. We conclude that during mammalian Golgi assembly components fit into a dynamic, first-formed, multigolgin-enriched framework that is initially cargo transport incompetent. Resumption of cargo transport precedes full Golgi assembly.
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Affiliation(s)
- Shu Jiang
- *Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR 72205; and
| | - Sung W. Rhee
- *Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR 72205; and
| | - Paul A. Gleeson
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Brian Storrie
- *Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR 72205; and
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47
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Miserey-Lenkei S, Couëdel-Courteille A, Del Nery E, Bardin S, Piel M, Racine V, Sibarita JB, Perez F, Bornens M, Goud B. A role for the Rab6A' GTPase in the inactivation of the Mad2-spindle checkpoint. EMBO J 2006; 25:278-89. [PMID: 16395330 PMCID: PMC1383512 DOI: 10.1038/sj.emboj.7600929] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Accepted: 11/30/2005] [Indexed: 12/21/2022] Open
Abstract
The two isoforms of the Rab6 GTPase, Rab6A and Rab6A', regulate a retrograde transport route connecting early endosomes and the endoplasmic reticulum via the Golgi complex in interphasic cells. Here we report that when Rab6A' function is altered cells are unable to progress normally through mitosis. Such cells are blocked in metaphase, despite displaying a normal Golgi fragmentation and with the Mad2-spindle checkpoint activated. Furthermore, the Rab6 effector p150(Glued), a subunit of the dynein/dynactin complex, remains associated with some kinetochores. A similar phenotype was observed when GAPCenA, a GTPase-activating protein of Rab6, was depleted from cells. Our results suggest that Rab6A' likely regulates the dynamics of the dynein/dynactin complex at the kinetochores and consequently the inactivation of the Mad2-spindle checkpoint. Rab6A', through its interaction with p150(Glued) and GAPCenA, may thus participate in a pathway involved in the metaphase/anaphase transition.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Bruno Goud
- UMR 144 CNRS/IC, Institut Curie, Paris, France
- UMR 144 CNRS/Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. Tel.: +33 1 4234 6398; Fax: +33 1 4234 6382; E-mail:
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48
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Altan-Bonnet N, Sougrat R, Liu W, Snapp EL, Ward T, Lippincott-Schwartz J. Golgi inheritance in mammalian cells is mediated through endoplasmic reticulum export activities. Mol Biol Cell 2005; 17:990-1005. [PMID: 16314396 PMCID: PMC1356606 DOI: 10.1091/mbc.e05-02-0155] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Golgi inheritance during mammalian cell division occurs through the disassembly, partitioning, and reassembly of Golgi membranes. The mechanisms responsible for these processes are poorly understood. To address these mechanisms, we have examined the identity and dynamics of Golgi proteins within mitotic membranes using live cell imaging and electron microscopy techniques. Mitotic Golgi fragments, seen in prometaphase and telophase, were found to localize adjacent to endoplasmic reticulum (ER) export domains, and resident Golgi transmembrane proteins cycled rapidly into and out of these fragments. Golgi proteins within mitotic Golgi haze-seen during metaphase-were found to redistribute with ER markers into fragments when the ER was fragmented by ionomycin treatment. The temperature-sensitive misfolding mutant ts045VSVG protein, when localized to the Golgi at the start of mitosis, became trapped in the ER at the end of mitosis in cells shifted to 40 degrees C. Finally, reporters for Arf1 and Sar1 activity revealed that Arf1 and Sar1 undergo sequential inactivation during mitotic Golgi breakdown and sequential reactivation upon Golgi reassembly at the end of mitosis. Together, these findings support a model of mitotic Golgi inheritance that involves inhibition and subsequent reactivation of cellular activities controlling the cycling of Golgi components into and out of the ER.
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Affiliation(s)
- Nihal Altan-Bonnet
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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Chandra S. Quantitative imaging of subcellular calcium stores in mammalian LLC-PK1 epithelial cells undergoing mitosis by SIMS ion microscopy. Eur J Cell Biol 2005; 84:783-97. [PMID: 16218191 DOI: 10.1016/j.ejcb.2005.05.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Quantitative 3-D total calcium gradients, representing subcellular stored calcium, were imaged with a CAMECA IMS-3f SIMS ion microscope in cryogenically prepared frozen freeze-dried LLC-PK1 cells captured in interphase and various stages of mitosis. 39K and 23Na concentrations were also measured in the same cells. Correlative optical (or SEM) and SIMS analysis of cells revealed a redistribution of the interphase Golgi calcium store in prophase and prometaphase cells. In metaphase cells, simultaneous SIMS imaging of total calcium in both the spindle and the non-spindle cytoplasm of individual cells revealed a gradual and dynamic alignment of calcium stores in both half-spindles prior to the onset of anaphase. The anaphase cells revealed the highest local total calcium concentrations in the spindle regions behind the daughter chromosomes and the lowest in the central spindle region. The pericentriolar material in telophase cells contained calcium stores. Quantitatively, a typical metaphase cell with well-aligned calcium stores in the spindle region contained 1.1 mM total calcium in each half-spindle, 0.8 mM total calcium in the non-spindle cytoplasm, and 0.5mM total calcium in the chromosomes. At the submicron scale, the distribution of total calcium was heterogeneous in the chromosomes, metaphase spindle, and non-spindle cytoplasm. An increased binding of calcium to chromosomes is not a physiological requirement for chromosomal condensation in mitosis, since interphase nuclei and mitotic chromosomes contained comparable total calcium concentrations measured per unit volume. A significant reduction of total calcium in the non-spindle cytoplasm was observed in the metaphase, anaphase, and telophase cells, which is indicative of the limited storage of the releasable calcium pool in these specific stages of mitosis. Direct total calcium measurements in subcellular regions confirmed that both the spindle and the non-spindle cytoplasm of metaphase cells contained inositol 1,4,5-trisphosphate (IP3)-sensitive calcium stores sensitive to arginine vasopressin, thapsigargin, and calcium ionophore A23187. The dynamic alignment of calcium stores in both half-spindles may be an integral part of the time-dependent process of a cell's overall preparation for exiting the metaphase stage in mammalian LLC-PK1 cells.
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Affiliation(s)
- Subhash Chandra
- Cornell SIMS Ion Microscopy Laboratory, Department of Earth and Atmospheric Sciences, Snee Hall, Cornell University, Ithaca, NY 14853, USA.
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50
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Rhee SW, Starr T, Forsten-Williams K, Storrie B. The Steady-State Distribution of Glycosyltransferases Between the Golgi Apparatus and the Endoplasmic Reticulum is Approximately 90:10. Traffic 2005; 6:978-90. [PMID: 16190979 DOI: 10.1111/j.1600-0854.2005.00333.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Several lines of evidence support a novel model for Golgi protein residency in which these proteins cycle between the Golgi apparatus and the endoplasmic reticulum (ER). However, to preserve the functional distinction between the two organelles, this pool of ER-resident Golgi enzymes must be small. We quantified the distribution for two Golgi glycosyltransferases in HeLa cells to test this prediction. We reasoned that best-practice, quantitative solutions would come from treating images as data arrays rather than pictures. Using deconvolution and computer calculated organellar boundaries, the Golgi fraction for both endogenous beta1,4-galactosyltransferase and UDP-N-acetylgalactosamine:polypeptide N-acetylgalactosaminyltransferase 2 fused with green fluorescent protein (GFP) was 91% by fluorescence microscopy. Immunogold labeling followed by electron microscopy and model analysis yielded a similar value. Values reflect steady-state conditions, as inclusion of a protein synthesis inhibitor had no effect. These data strongly suggest that the fluorescence of a GFP chimera with an organellar protein can be a valid indicator of protein distribution and more generally that fluorescent microscopy can provide a valid, rapid approach for protein quantification. In conclusion, we find the ER pool of cycling Golgi glycosyltransferases is small and approximately 1/100 the concentration found in the Golgi apparatus.
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Affiliation(s)
- Sung Wu Rhee
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA
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