1
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Grazzini A, Cavanaugh AM. Fungal microtubule organizing centers are evolutionarily unstable structures. Fungal Genet Biol 2024; 172:103885. [PMID: 38485050 DOI: 10.1016/j.fgb.2024.103885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 03/07/2024] [Accepted: 03/11/2024] [Indexed: 03/24/2024]
Abstract
For most Eukaryotic species the requirements of cilia formation dictate the structure of microtubule organizing centers (MTOCs). In this study we find that loss of cilia corresponds to loss of evolutionary stability for fungal MTOCs. We used iterative search algorithms to identify proteins homologous to those found in Saccharomyces cerevisiae, and Schizosaccharomyces pombe MTOCs, and calculated site-specific rates of change for those proteins that were broadly phylogenetically distributed. Our results indicate that both the protein composition of MTOCs as well as the sequence of MTOC proteins are poorly conserved throughout the fungal kingdom. To begin to reconcile this rapid evolutionary change with the rigid structure and essential function of the S. cerevisiae MTOC we further analyzed how structural interfaces among proteins influence the rates of change for specific residues within a protein. We find that a more stable protein may stabilize portions of an interacting partner where the two proteins are in contact. In summary, while the protein composition and sequences of the MTOC may be rapidly changing the proteins within the structure have a stabilizing effect on one another. Further exploration of fungal MTOCs will expand our understanding of how changes in the functional needs of a cell have affected physical structures, proteomes, and protein sequences throughout fungal evolution.
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Affiliation(s)
- Adam Grazzini
- Department of Biology, Creighton University, Omaha, Nebraska, USA
| | - Ann M Cavanaugh
- Department of Biology, Creighton University, Omaha, Nebraska, USA.
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2
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Kume K, Nishikawa K, Furuyama R, Fujimoto T, Koyano T, Matsuyama M, Mizunuma M, Hirata D. The fission yeast NDR kinase Orb6 and its signalling pathway MOR regulate cytoplasmic microtubule organization during the cell cycle. Open Biol 2024; 14:230440. [PMID: 38442865 PMCID: PMC10914512 DOI: 10.1098/rsob.230440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 01/04/2024] [Indexed: 03/07/2024] Open
Abstract
Microtubule organization and reorganization during the cell cycle are achieved by regulation of the number, distribution and activity of microtubule-organizing centres (MTOCs). In fission yeast, the Mto1/2 complex determines the activity and distribution of cytoplasmic MTOCs. Upon mitosis, cytoplasmic microtubule nucleation ceases; inactivation of the Mto1/2 complex is triggered by Mto2 hyperphosphorylation. However, the protein kinase(s) that phosphorylates Mto2 remains elusive. Here we show that a conserved signalling network, called MOR (morphogenesis Orb6 network) in fission yeast, negatively regulates cytoplasmic MTOCs through Mto2 phosphorylation to ensure proper microtubule organization. Inactivation of Orb6 kinase, the most downstream MOR component, by attenuation of MOR signalling leads to reduced Mto2 phosphorylation, coincident with increased number of both Mto2 puncta and cytoplasmic microtubules. These defects cause the emergence of uncoordinated mitotic cells with cytoplasmic microtubules, resulting in reduced spindle assembly. Thus, the regulation of Mto2 by the MOR is crucial for cytoplasmic microtubule organization and contributes to reorganization of the microtubule cytoskeletons during the cell cycle.
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Affiliation(s)
- Kazunori Kume
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
- Hiroshima Research Center for Healthy Aging (HiHA), Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Kenji Nishikawa
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Rikuto Furuyama
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Takahiro Fujimoto
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Takayuki Koyano
- Division of Cell Biology, Shigei Medical Research Institute, 2117 Yamada, Minami-ku, Okayama 701-0202, Japan
| | - Makoto Matsuyama
- Division of Molecular Genetics, Shigei Medical Research Institute, 2117 Yamada, Minami-ku, Okayama 701-0202, Japan
| | - Masaki Mizunuma
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
- Hiroshima Research Center for Healthy Aging (HiHA), Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Dai Hirata
- Faculty of Agriculture, Niigata University, 2-8050 Ikarashi, Niigata 950-2181, Japan
- Sakeology Center, Niigata University, 2-8050 Ikarashi, Niigata 950-2181, Japan
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3
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Jain I, Rao M, Tran PT. Reliable and robust control of nucleus centering is contingent on nonequilibrium force patterns. iScience 2023; 26:106665. [PMID: 37182105 PMCID: PMC10173738 DOI: 10.1016/j.isci.2023.106665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 02/23/2023] [Accepted: 04/09/2023] [Indexed: 05/16/2023] Open
Abstract
Cell centers their division apparatus to ensure symmetric cell division, a challenging task when the governing dynamics is stochastic. Using fission yeast, we show that the patterning of nonequilibrium polymerization forces of microtubule (MT) bundles controls the precise localization of spindle pole body (SPB), and hence the division septum, at the onset of mitosis. We define two cellular objectives, reliability, the mean SPB position relative to the geometric center, and robustness, the variance of the SPB position, which are sensitive to genetic perturbations that change cell length, MT bundle number/orientation, and MT dynamics. We show that simultaneous control of reliability and robustness is required to minimize septum positioning error achieved by the wild type (WT). A stochastic model for the MT-based nucleus centering, with parameters measured directly or estimated using Bayesian inference, recapitulates the maximum fidelity of WT. Using this, we perform a sensitivity analysis of the parameters that control nuclear centering.
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Affiliation(s)
- Ishutesh Jain
- Institut Curie, PSL Universite, Sorbonne Universite, CNRS UMR 144, 75005 Paris, France
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences - TIFR, Bangalore 560065, India
| | - Madan Rao
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences - TIFR, Bangalore 560065, India
- Corresponding author
| | - Phong T. Tran
- Institut Curie, PSL Universite, Sorbonne Universite, CNRS UMR 144, 75005 Paris, France
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Corresponding author
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4
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Wevers C, Höhler M, Alcázar-Román AR, Hegemann JH, Fleig U. A Functional Yeast-Based Screen Identifies the Host Microtubule Cytoskeleton as a Target of Numerous Chlamydia pneumoniae Proteins. Int J Mol Sci 2023; 24:ijms24087618. [PMID: 37108781 PMCID: PMC10142024 DOI: 10.3390/ijms24087618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 04/13/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Bacterial pathogens have evolved intricate ways to manipulate the host to support infection. Here, we systematically assessed the importance of the microtubule cytoskeleton for infection by Chlamydiae, which are obligate intracellular bacteria that are of great importance for human health. The elimination of microtubules in human HEp-2 cells prior to C. pneumoniae infection profoundly attenuated the infection efficiency, demonstrating the need for microtubules for the early infection processes. To identify microtubule-modulating C. pneumoniae proteins, a screen in the model yeast Schizosaccharomyces pombe was performed. Unexpectedly, among 116 selected chlamydial proteins, more than 10%, namely, 13 proteins, massively altered the yeast interphase microtubule cytoskeleton. With two exceptions, these proteins were predicted to be inclusion membrane proteins. As proof of principle, we selected the conserved CPn0443 protein, which caused massive microtubule instability in yeast, for further analysis. CPn0443 bound and bundled microtubules in vitro and co-localized partially with microtubules in vivo in yeast and human cells. Furthermore, CPn0443-transfected U2OS cells had a significantly reduced infection rate by C. pneumoniae EBs. Thus, our yeast screen identified numerous proteins encoded using the highly reduced C. pneumoniae genome that modulated microtubule dynamics. Hijacking of the host microtubule cytoskeleton must be a vital part of chlamydial infection.
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Affiliation(s)
- Carolin Wevers
- Eukaryotic Microbiology, Institute of Functional Microbial Genomics, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Mona Höhler
- Eukaryotic Microbiology, Institute of Functional Microbial Genomics, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Abel R Alcázar-Román
- Eukaryotic Microbiology, Institute of Functional Microbial Genomics, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Johannes H Hegemann
- Institute of Functional Microbial Genomics, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Ursula Fleig
- Eukaryotic Microbiology, Institute of Functional Microbial Genomics, Heinrich-Heine-University, 40225 Düsseldorf, Germany
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5
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Rogers AM, Egan MJ. Septum-associated microtubule organizing centers within conidia support infectious development by the blast fungus Magnaporthe oryzae. Fungal Genet Biol 2023; 165:103768. [PMID: 36596442 DOI: 10.1016/j.fgb.2022.103768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 12/16/2022] [Accepted: 12/22/2022] [Indexed: 01/01/2023]
Abstract
Cytoplasmic microtubule arrays play important and diverse roles within fungal cells, including serving as molecular highways for motor-driven organelle motility. While the dynamic plus ends of cytoplasmic microtubules are free to explore the cytoplasm through their stochastic growth and shrinkage, their minus ends are nucleated at discrete organizing centers, composed of large multi-subunit protein complexes. The location and composition of these microtubule organizing centers varies depending on genus, cell type, and in some instances cell-cycle stage. Despite their obvious importance, our understanding of the nature, diversity, and regulation of microtubule organizing centers in fungi remains incomplete. Here, using three-color fluorescence microscopy based live-cell imaging, we investigate the organization and dynamic behavior of the microtubule cytoskeleton within infection-related cell types of the filamentous fungus,Magnaporthe oryzae, a highly destructive pathogen of rice and wheat. We provide data to support the idea that cytoplasmic microtubules are nucleated at septa, rather than at nuclear spindle pole bodies, within the three-celled blast conidium, and provide new insight into remodeling of the microtubule cytoskeleton during nuclear division and inheritance. Lastly, we provide a more complete picture of the architecture and subcellular organization of the prototypical blast appressorium, a specialized pressure-generating cell type used to invade host tissue. Taken together, our study provides new insight into microtubule nucleation, organization, and dynamics in specialized and differentiated fungal cell types.
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Affiliation(s)
- Audra Mae Rogers
- Department of Entomology and Plant Pathology, University of Arkansas, Fayetteville, AR 72701, USA
| | - Martin John Egan
- Department of Entomology and Plant Pathology, University of Arkansas, Fayetteville, AR 72701, USA.
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6
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Chacko LA, Mikus F, Ariotti N, Dey G, Ananthanarayanan V. Microtubule-mitochondrial attachment facilitates cell division symmetry and mitochondrial partitioning in fission yeast. J Cell Sci 2023; 136:286576. [PMID: 36633091 PMCID: PMC10112971 DOI: 10.1242/jcs.260705] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 11/29/2022] [Indexed: 01/13/2023] Open
Abstract
Association with microtubules inhibits the fission of mitochondria in Schizosaccharomyces pombe. Here, we show that this attachment of mitochondria to microtubules is an important cell-intrinsic factor in determining cell division symmetry. By comparing mutant cells that exhibited enhanced attachment and no attachment of mitochondria to microtubules (Dnm1Δ and Mmb1Δ, respectively), we show that microtubules in these mutants displayed aberrant dynamics compared to wild-type cells, which resulted in errors in nuclear positioning. This translated to cell division asymmetry in a significant proportion of both Dnm1Δ and Mmb1Δ cells. Asymmetric division in Dnm1Δ and Mmb1Δ cells resulted in unequal distribution of mitochondria, with the daughter cell that received more mitochondria growing faster than the other daughter cell. Taken together, we show the existence of homeostatic feedback controls between mitochondria and microtubules in fission yeast, which directly influence mitochondrial partitioning and, thereby, cell growth. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Leeba Ann Chacko
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bengaluru 560012, India
| | - Felix Mikus
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, 69120 Heidelberg, Germany
| | - Nicholas Ariotti
- Centre for Cell Biology of Chronic Disease, Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia
| | - Gautam Dey
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
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7
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Arginylation Regulates Cytoskeleton Organization and Cell Division and Affects Mitochondria in Fission Yeast. Mol Cell Biol 2022; 42:e0026122. [PMID: 36226970 PMCID: PMC9670973 DOI: 10.1128/mcb.00261-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Protein arginylation mediated by arginyltransferase Ate1 is a posttranslational modification of emerging importance implicated in the regulation of mammalian embryogenesis, the cardiovascular system, tissue morphogenesis, cell migration, neurodegeneration, cancer, and aging. Ate1 deletion results in embryonic lethality in mice but does not affect yeast viability, making yeast an ideal system to study the molecular pathways regulated by arginylation. Here, we conducted a global analysis of cytoskeleton-related arginylation-dependent phenotypes in Schizosaccharomyces pombe, a fission yeast species that shares many fundamental features of higher eukaryotic cells. Our studies revealed roles of Ate1 in cell division, cell polarization, organelle transport, and interphase cytoskeleton organization and dynamics. We also found a role of Ate1 in mitochondria morphology and maintenance. Furthermore, targeted mass spectrometry analysis of the total Sc. pombe arginylome identified a number of arginylated proteins, including those that play direct roles in these processes; lack of their arginylation may be responsible for ate1-knockout phenotypes. Our work outlines global biological processes potentially regulated by arginylation and paves the way to unraveling the functions of protein arginylation that are conserved at multiple levels of evolution and potentially constitute the primary role of this modification in vivo.
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8
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Molines AT, Lemière J, Gazzola M, Steinmark IE, Edrington CH, Hsu CT, Real-Calderon P, Suhling K, Goshima G, Holt LJ, Thery M, Brouhard GJ, Chang F. Physical properties of the cytoplasm modulate the rates of microtubule polymerization and depolymerization. Dev Cell 2022; 57:466-479.e6. [PMID: 35231427 PMCID: PMC9319896 DOI: 10.1016/j.devcel.2022.02.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 11/01/2021] [Accepted: 01/31/2022] [Indexed: 11/20/2022]
Abstract
The cytoplasm is a crowded, visco-elastic environment whose physical properties change according to physiological or developmental states. How the physical properties of the cytoplasm impact cellular functions in vivo remains poorly understood. Here, we probe the effects of cytoplasmic concentration on microtubules by applying osmotic shifts to fission yeast, moss, and mammalian cells. We show that the rates of both microtubule polymerization and depolymerization scale linearly and inversely with cytoplasmic concentration; an increase in cytoplasmic concentration decreases the rates of microtubule polymerization and depolymerization proportionally, whereas a decrease in cytoplasmic concentration leads to the opposite. Numerous lines of evidence indicate that these effects are due to changes in cytoplasmic viscosity rather than cellular stress responses or macromolecular crowding per se. We reconstituted these effects on microtubules in vitro by tuning viscosity. Our findings indicate that, even in normal conditions, the viscosity of the cytoplasm modulates the reactions that underlie microtubule dynamic behaviors.
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Affiliation(s)
- Arthur T Molines
- Department of Cell and Tissue Biology, University of California, San Francisco, USA; Marine Biological Laboratory, Woods Hole, MA 02543, USA.
| | - Joël Lemière
- Department of Cell and Tissue Biology, University of California, San Francisco, USA
| | - Morgan Gazzola
- University of Grenoble-Alpes, CEA, CNRS, INRA, Interdisciplinary Research Institute of Grenoble, Laboratoire de Phyiologie Cellulaire & Vegétale, CytoMorpho Lab, 38054 Grenoble, France
| | | | | | - Chieh-Ting Hsu
- Department of Physics, McGill University, Montréal, Quebec, Canada
| | - Paula Real-Calderon
- Department of Cell and Tissue Biology, University of California, San Francisco, USA
| | - Klaus Suhling
- Department of Physics, King's College London, London, UK
| | - Gohta Goshima
- Sugashima Marine Biological Laboratory and Division of Biological Science, Graduate School of Science, Nagoya University, Toba City, Mie, Japan; Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Liam J Holt
- Institute for Systems Genetics, New York University Langone Health, New York, NY 10016, USA; Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Manuel Thery
- University of Grenoble-Alpes, CEA, CNRS, INRA, Interdisciplinary Research Institute of Grenoble, Laboratoire de Phyiologie Cellulaire & Vegétale, CytoMorpho Lab, 38054 Grenoble, France; Université de Paris, INSERM, CEA, Institut de Recherche Saint Louis, U 976, CytoMorpho Lab, 75010 Paris, France
| | - Gary J Brouhard
- Department of Biology, McGill University, Montréal, Quebec, Canada
| | - Fred Chang
- Department of Cell and Tissue Biology, University of California, San Francisco, USA; Marine Biological Laboratory, Woods Hole, MA 02543, USA.
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9
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Zareiesfandabadi P, Elting MW. Force by minus-end motors Dhc1 and Klp2 collapses the S. pombe spindle after laser ablation. Biophys J 2022; 121:263-276. [PMID: 34951983 PMCID: PMC8790213 DOI: 10.1016/j.bpj.2021.12.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 11/19/2021] [Accepted: 12/16/2021] [Indexed: 01/21/2023] Open
Abstract
A microtubule-based machine called the mitotic spindle segregates chromosomes when eukaryotic cells divide. In the fission yeast Schizosaccharomyces pombe, which undergoes closed mitosis, the spindle forms a single bundle of microtubules inside the nucleus. During elongation, the spindle extends via antiparallel microtubule sliding by molecular motors. These extensile forces from the spindle are thought to resist compressive forces from the nucleus. We probe the mechanism and maintenance of this force balance via laser ablation of spindles at various stages of mitosis. We find that spindle pole bodies collapse toward each other after ablation, but spindle geometry is often rescued, allowing spindles to resume elongation. Although this basic behavior has been previously observed, many questions remain about the phenomenon's dynamics, mechanics, and molecular requirements. In this work, we find that previously hypothesized viscoelastic relaxation of the nucleus cannot explain spindle shortening in response to laser ablation. Instead, spindle collapse requires microtubule dynamics and is powered by the minus-end-directed motor proteins dynein Dhc1 and kinesin-14 Klp2, but it does not require the minus-end-directed kinesin Pkl1.
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Affiliation(s)
| | - Mary Williard Elting
- Department of Physics, North Carolina State University, Raleigh, North Carolina,Cluster for Quantitative and Computational Developmental Biology, North Carolina State University, Raleigh, North Carolina,Corresponding author
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10
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Ashraf S, Tay YD, Kelly DA, Sawin KE. Microtubule-independent movement of the fission yeast nucleus. J Cell Sci 2021; 134:jcs.253021. [PMID: 33602740 PMCID: PMC8015250 DOI: 10.1242/jcs.253021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 02/09/2021] [Indexed: 12/14/2022] Open
Abstract
Movement of the cell nucleus typically involves the cytoskeleton and either polymerization-based pushing forces or motor-based pulling forces. In the fission yeast Schizosaccharomyces pombe, nuclear movement and positioning are thought to depend on microtubule polymerization-based pushing forces. Here, we describe a novel, microtubule-independent, form of nuclear movement in fission yeast. Microtubule-independent nuclear movement is directed towards growing cell tips, and it is strongest when the nucleus is close to a growing cell tip, and weakest when the nucleus is far from that tip. Microtubule-independent nuclear movement requires actin cables but does not depend on actin polymerization-based pushing or myosin V-based pulling forces. The vesicle-associated membrane protein (VAMP)-associated proteins (VAPs) Scs2 and Scs22, which are critical for endoplasmic reticulum-plasma membrane contact sites in fission yeast, are also required for microtubule-independent nuclear movement. We also find that in cells in which microtubule-based pushing forces are present, disruption of actin cables leads to increased fluctuations in interphase nuclear positioning and subsequent altered septation. Our results suggest two non-exclusive mechanisms for microtubule-independent nuclear movement, which may help illuminate aspects of nuclear positioning in other cells.
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11
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Dundon SER, Pollard TD. Microtubule nucleation promoters Mto1 and Mto2 regulate cytokinesis in fission yeast. Mol Biol Cell 2020; 31:1846-1856. [PMID: 32520628 PMCID: PMC7525812 DOI: 10.1091/mbc.e19-12-0686] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 05/26/2020] [Accepted: 06/04/2020] [Indexed: 01/16/2023] Open
Abstract
Microtubules of the mitotic spindle direct cytokinesis in metazoans but this has not been documented in fungi. We report evidence that microtubule nucleators at the spindle pole body help coordinate cytokinetic furrow formation in fission yeast. The temperature-sensitive cps1-191 strain (Liu et al., 1999) with a D277N substitution in β-glucan synthase 1 (Cps1/Bgs1) was reported to arrest with an unconstricted contractile ring. We discovered that contractile rings in cps1-191 cells constrict slowly and that an mto2S338N mutation is required with the bgs1D277Nmutation to reproduce the cps1-191 phenotype. Complexes of Mto2 and Mto1 with γ-tubulin regulate microtubule assembly. Deletion of Mto1 along with the bgs1D277N mutation also gives the cps1-191 phenotype, which is not observed in mto2S338N or mto1Δ cells expressing bgs1+. Both mto2S338N and mto1Δ cells nucleate fewer astral microtubules than normal and have higher levels of Rho1-GTP at the division site than wild-type cells. We report multiple conditions that sensitize mto1Δ and mto2S338N cells to furrow ingression phenotypes.
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Affiliation(s)
- Samantha E. R. Dundon
- Departments of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103
| | - Thomas D. Pollard
- Departments of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103
- Departments of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103
- Department of Cell Biology, Yale University, New Haven, CT 06520-8103
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12
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Liu W, Zheng F, Wang Y, Fu C. Alp7-Mto1 and Alp14 synergize to promote interphase microtubule regrowth from the nuclear envelope. J Mol Cell Biol 2020; 11:944-955. [PMID: 31087092 PMCID: PMC6927237 DOI: 10.1093/jmcb/mjz038] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 03/15/2019] [Accepted: 04/26/2019] [Indexed: 01/02/2023] Open
Abstract
Microtubules grow not only from the centrosome but also from various noncentrosomal microtubule-organizing centers (MTOCs), including the nuclear envelope (NE) and pre-existing microtubules. The evolutionarily conserved proteins Mto1/CDK5RAP2 and Alp14/TOG/XMAP215 have been shown to be involved in promoting microtubule nucleation. However, it has remained elusive as to how the microtubule nucleation promoting factors are specified to various noncentrosomal MTOCs, particularly the NE, and how these proteins coordinate to organize microtubule assembly. Here, we demonstrate that in the fission yeast Schizosaccharomyces pombe, efficient interphase microtubule growth from the NE requires Alp7/TACC, Alp14/TOG/XMAP215, and Mto1/CDK5RAP2. The absence of Alp7, Alp14, or Mto1 compromises microtubule regrowth on the NE in cells undergoing microtubule repolymerization. We further demonstrate that Alp7 and Mto1 interdependently localize to the NE in cells without microtubules and that Alp14 localizes to the NE in an Alp7 and Mto1-dependent manner. Tethering Mto1 to the NE in cells lacking Alp7 partially restores microtubule number and the efficiency of microtubule generation from the NE. Hence, our study delineates that Alp7, Alp14, and Mto1 work in concert to regulate interphase microtubule regrowth on the NE.
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Affiliation(s)
- Wenyue Liu
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei, China
| | - Fan Zheng
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei, China
| | - Yucai Wang
- School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Chuanhai Fu
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei, China
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13
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Kim SM, Tripathi VP, Shen KF, Forsburg SL. Checkpoint Regulation of Nuclear Tos4 Defines S Phase Arrest in Fission Yeast. G3 (BETHESDA, MD.) 2020; 10:255-266. [PMID: 31719112 PMCID: PMC6945033 DOI: 10.1534/g3.119.400726] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 11/11/2019] [Indexed: 01/21/2023]
Abstract
From yeast to humans, the cell cycle is tightly controlled by regulatory networks that regulate cell proliferation and can be monitored by dynamic visual markers in living cells. We have observed S phase progression by monitoring nuclear accumulation of the FHA-containing DNA binding protein Tos4, which is expressed in the G1/S phase transition. We use Tos4 localization to distinguish three classes of DNA replication mutants: those that arrest with an apparent 1C DNA content and accumulate Tos4 at the restrictive temperature; those that arrest with an apparent 2C DNA content, that do not accumulate Tos4; and those that proceed into mitosis despite a 1C DNA content, again without Tos4 accumulation. Our data indicate that Tos4 localization in these conditions is responsive to checkpoint kinases, with activation of the Cds1 checkpoint kinase promoting Tos4 retention in the nucleus, and activation of the Chk1 damage checkpoint promoting its turnover. Tos4 localization therefore allows us to monitor checkpoint-dependent activation that responds to replication failure in early vs. late S phase.
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Affiliation(s)
- Seong M Kim
- Program in Molecular and Computational Biology, University of Southern California, Los Angeles CA 90089
| | - Vishnu P Tripathi
- Program in Molecular and Computational Biology, University of Southern California, Los Angeles CA 90089
| | - Kuo-Fang Shen
- Program in Molecular and Computational Biology, University of Southern California, Los Angeles CA 90089
| | - Susan L Forsburg
- Program in Molecular and Computational Biology, University of Southern California, Los Angeles CA 90089
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14
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Liang X. Microtubule nucleation and dynamic instability in interphase fission yeast. J Mol Cell Biol 2019; 11:941-943. [PMID: 31125408 PMCID: PMC6927234 DOI: 10.1093/jmcb/mjz044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 05/17/2019] [Indexed: 11/17/2022] Open
Affiliation(s)
- Xin Liang
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.,Max-Planck Partner Group, School of Life Sciences, Tsinghua University, Beijing 100084, China
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15
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Gallardo P, Barrales RR, Daga RR, Salas-Pino S. Nuclear Mechanics in the Fission Yeast. Cells 2019; 8:cells8101285. [PMID: 31635174 PMCID: PMC6829894 DOI: 10.3390/cells8101285] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/14/2019] [Accepted: 10/17/2019] [Indexed: 12/13/2022] Open
Abstract
In eukaryotic cells, the organization of the genome within the nucleus requires the nuclear envelope (NE) and its associated proteins. The nucleus is subjected to mechanical forces produced by the cytoskeleton. The physical properties of the NE and the linkage of chromatin in compacted conformation at sites of cytoskeleton contacts seem to be key for withstanding nuclear mechanical stress. Mechanical perturbations of the nucleus normally occur during nuclear positioning and migration. In addition, cell contraction or expansion occurring for instance during cell migration or upon changes in osmotic conditions also result innuclear mechanical stress. Recent studies in Schizosaccharomyces pombe (fission yeast) have revealed unexpected functions of cytoplasmic microtubules in nuclear architecture and chromosome behavior, and have pointed to NE-chromatin tethers as protective elements during nuclear mechanics. Here, we review and discuss how fission yeast cells can be used to understand principles underlying the dynamic interplay between genome organization and function and the effect of forces applied to the nucleus by the microtubule cytoskeleton.
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Affiliation(s)
- Paola Gallardo
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas, Junta de Andalucia, 41010 Seville, Spain.
| | - Ramón R Barrales
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas, Junta de Andalucia, 41010 Seville, Spain.
| | - Rafael R Daga
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas, Junta de Andalucia, 41010 Seville, Spain.
| | - Silvia Salas-Pino
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas, Junta de Andalucia, 41010 Seville, Spain.
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16
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Loiodice I, Janson ME, Tavormina P, Schaub S, Bhatt D, Cochran R, Czupryna J, Fu C, Tran PT. Quantifying Tubulin Concentration and Microtubule Number Throughout the Fission Yeast Cell Cycle. Biomolecules 2019; 9:biom9030086. [PMID: 30836700 PMCID: PMC6468777 DOI: 10.3390/biom9030086] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 02/26/2019] [Indexed: 11/16/2022] Open
Abstract
The fission yeast Schizosaccharomyces pombe serves as a good genetic model organism for the molecular dissection of the microtubule (MT) cytoskeleton. However, analysis of the number and distribution of individual MTs throughout the cell cycle, particularly during mitosis, in living cells is still lacking, making quantitative modelling imprecise. We use quantitative fluorescent imaging and analysis to measure the changes in tubulin concentration and MT number and distribution throughout the cell cycle at a single MT resolution in living cells. In the wild-type cell, both mother and daughter spindle pole body (SPB) nucleate a maximum of 23 ± 6 MTs at the onset of mitosis, which decreases to a minimum of 4 ± 1 MTs at spindle break down. Interphase MT bundles, astral MT bundles, and the post anaphase array (PAA) microtubules are composed primarily of 1 ± 1 individual MT along their lengths. We measure the cellular concentration of αβ-tubulin subunits to be ~5 µM throughout the cell cycle, of which one-third is in polymer form during interphase and one-quarter is in polymer form during mitosis. This analysis provides a definitive characterization of αβ-tubulin concentration and MT number and distribution in fission yeast and establishes a foundation for future quantitative comparison of mutants defective in MTs.
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Affiliation(s)
- Isabelle Loiodice
- Cell & Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Marcel E Janson
- Cell & Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Sebastien Schaub
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005 Paris, France
| | - Divya Bhatt
- Cell & Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ryan Cochran
- Cell & Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Julie Czupryna
- Cell & Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Chuanhai Fu
- Cell & Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Phong T Tran
- Cell & Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005 Paris, France.
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17
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Shen J, Li T, Niu X, Liu W, Zheng S, Wang J, Wang F, Cao X, Yao X, Zheng F, Fu C. The J-domain cochaperone Rsp1 interacts with Mto1 to organize noncentrosomal microtubule assembly. Mol Biol Cell 2019; 30:256-267. [PMID: 30427751 PMCID: PMC6589567 DOI: 10.1091/mbc.e18-05-0279] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Microtubule biogenesis initiates at various intracellular sites, including the centrosome, the Golgi apparatus, the nuclear envelope, and preexisting microtubules. Similarly, in the fission yeast Schizosaccharomyces pombe, interphase microtubules are nucleated at the spindle pole body (SPB), the nuclear envelope, and preexisting microtubules, depending on Mto1 activity. Despite the essential role of Mto1 in promoting microtubule nucleation, how distribution of Mto1 in different sites is regulated has remained elusive. Here, we show that the J-domain cochaperone Rsp1 interacts with Mto1 and specifies the localization of Mto1 to non-SPB nucleation sites. The absence of Rsp1 abolishes the localization of Mto1 to non-SPB nucleation sites, with concomitant enrichment of Mto1 to the SPB and the nuclear envelope. In contrast, Rsp1 overexpression impairs the localization of Mto1 to all microtubule organization sites. These findings delineate a previously uncharacterized mechanism in which Rsp1-Mto1 interaction orchestrates non-SPB microtubule formation.
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Affiliation(s)
- Juan Shen
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Tianpeng Li
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Xiaojia Niu
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Wenyue Liu
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Shengnan Zheng
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Jing Wang
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Fengsong Wang
- School of Life Sciences, Anhui Medical University, Hefei, Anhui 230027, China
| | - Xinwang Cao
- School of Life Sciences, Anhui Medical University, Hefei, Anhui 230027, China
| | - Xuebiao Yao
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Fan Zheng
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Chuanhai Fu
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
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18
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Tay YD, Leda M, Goryachev AB, Sawin KE. Local and global Cdc42 guanine nucleotide exchange factors for fission yeast cell polarity are coordinated by microtubules and the Tea1-Tea4-Pom1 axis. J Cell Sci 2018; 131:jcs.216580. [PMID: 29930085 PMCID: PMC6080602 DOI: 10.1242/jcs.216580] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 06/14/2018] [Indexed: 12/30/2022] Open
Abstract
The conserved Rho-family GTPase Cdc42 plays a central role in eukaryotic cell polarity. The rod-shaped fission yeast Schizosaccharomyces pombe has two Cdc42 guanine nucleotide exchange factors (GEFs), Scd1 and Gef1, but little is known about how they are coordinated in polarized growth. Although the microtubule cytoskeleton is normally not required for polarity maintenance in fission yeast, we show here that when scd1 function is compromised, disruption of microtubules or the polarity landmark proteins Tea1, Tea4 or Pom1 leads to disruption of polarized growth. Instead, cells adopt an isotropic-like pattern of growth, which we term PORTLI growth. Surprisingly, PORTLI growth is caused by spatially inappropriate activity of Gef1. Although most Cdc42 GEFs are membrane associated, we find that Gef1 is a broadly distributed cytosolic protein rather than a membrane-associated protein at cell tips like Scd1. Microtubules and the Tea1–Tea4–Pom1 axis counteract inappropriate Gef1 activity by regulating the localization of the Cdc42 GTPase-activating protein Rga4. Our results suggest a new model of fission yeast cell polarity regulation, involving coordination of ‘local’ (Scd1) and ‘global’ (Gef1) Cdc42 GEFs via microtubules and microtubule-dependent polarity landmarks. Highlighted Article: Cell polarity in fission yeast is regulated by two different Cdc42 guanine nucleotide exchange factors, coordinated by the microtubule-dependent landmark system.
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Affiliation(s)
- Ye Dee Tay
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Marcin Leda
- SynthSys - Centre for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, CH Waddington Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Andrew B Goryachev
- SynthSys - Centre for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, CH Waddington Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Kenneth E Sawin
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
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19
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Riquelme M, Aguirre J, Bartnicki-García S, Braus GH, Feldbrügge M, Fleig U, Hansberg W, Herrera-Estrella A, Kämper J, Kück U, Mouriño-Pérez RR, Takeshita N, Fischer R. Fungal Morphogenesis, from the Polarized Growth of Hyphae to Complex Reproduction and Infection Structures. Microbiol Mol Biol Rev 2018; 82:e00068-17. [PMID: 29643171 PMCID: PMC5968459 DOI: 10.1128/mmbr.00068-17] [Citation(s) in RCA: 183] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Filamentous fungi constitute a large group of eukaryotic microorganisms that grow by forming simple tube-like hyphae that are capable of differentiating into more-complex morphological structures and distinct cell types. Hyphae form filamentous networks by extending at their tips while branching in subapical regions. Rapid tip elongation requires massive membrane insertion and extension of the rigid chitin-containing cell wall. This process is sustained by a continuous flow of secretory vesicles that depends on the coordinated action of the microtubule and actin cytoskeletons and the corresponding motors and associated proteins. Vesicles transport cell wall-synthesizing enzymes and accumulate in a special structure, the Spitzenkörper, before traveling further and fusing with the tip membrane. The place of vesicle fusion and growth direction are enabled and defined by the position of the Spitzenkörper, the so-called cell end markers, and other proteins involved in the exocytic process. Also important for tip extension is membrane recycling by endocytosis via early endosomes, which function as multipurpose transport vehicles for mRNA, septins, ribosomes, and peroxisomes. Cell integrity, hyphal branching, and morphogenesis are all processes that are largely dependent on vesicle and cytoskeleton dynamics. When hyphae differentiate structures for asexual or sexual reproduction or to mediate interspecies interactions, the hyphal basic cellular machinery may be reprogrammed through the synthesis of new proteins and/or the modification of protein activity. Although some transcriptional networks involved in such reprogramming of hyphae are well studied in several model filamentous fungi, clear connections between these networks and known determinants of hyphal morphogenesis are yet to be established.
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Affiliation(s)
- Meritxell Riquelme
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico
| | - Jesús Aguirre
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Salomon Bartnicki-García
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico
| | - Gerhard H Braus
- Department of Molecular Microbiology and Genetics and Goettingen Center for Molecular Biosciences (GZMB), University of Goettingen, Goettingen, Germany
| | - Michael Feldbrügge
- Institute for Microbiology, Heinrich Heine University Düsseldorf, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Ursula Fleig
- Institute for Functional Genomics of Microorganisms, Heinrich Heine University Düsseldorf, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Wilhelm Hansberg
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Alfredo Herrera-Estrella
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Irapuato, Mexico
| | - Jörg Kämper
- Karlsruhe Institute of Technology-South Campus, Institute for Applied Biosciences, Karlsruhe, Germany
| | - Ulrich Kück
- Ruhr University Bochum, Lehrstuhl für Allgemeine und Molekulare Botanik, Bochum, Germany
| | - Rosa R Mouriño-Pérez
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico
| | - Norio Takeshita
- University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Japan
| | - Reinhard Fischer
- Karlsruhe Institute of Technology-South Campus, Institute for Applied Biosciences, Karlsruhe, Germany
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20
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Bao XX, Spanos C, Kojidani T, Lynch EM, Rappsilber J, Hiraoka Y, Haraguchi T, Sawin KE. Exportin Crm1 is repurposed as a docking protein to generate microtubule organizing centers at the nuclear pore. eLife 2018; 7:e33465. [PMID: 29809148 PMCID: PMC6008054 DOI: 10.7554/elife.33465] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 05/21/2018] [Indexed: 01/04/2023] Open
Abstract
Non-centrosomal microtubule organizing centers (MTOCs) are important for microtubule organization in many cell types. In fission yeast Schizosaccharomyces pombe, the protein Mto1, together with partner protein Mto2 (Mto1/2 complex), recruits the γ-tubulin complex to multiple non-centrosomal MTOCs, including the nuclear envelope (NE). Here, we develop a comparative-interactome mass spectrometry approach to determine how Mto1 localizes to the NE. Surprisingly, we find that Mto1, a constitutively cytoplasmic protein, docks at nuclear pore complexes (NPCs), via interaction with exportin Crm1 and cytoplasmic FG-nucleoporin Nup146. Although Mto1 is not a nuclear export cargo, it binds Crm1 via a nuclear export signal-like sequence, and docking requires both Ran in the GTP-bound state and Nup146 FG repeats. In addition to determining the mechanism of MTOC formation at the NE, our results reveal a novel role for Crm1 and the nuclear export machinery in the stable docking of a cytoplasmic protein complex at NPCs.
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Affiliation(s)
- Xun X Bao
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Christos Spanos
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Tomoko Kojidani
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Department of Chemical and Biological Sciences, Faculty of ScienceJapan Women’s UniversityTokyoJapan
| | - Eric M Lynch
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Juri Rappsilber
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
- Department of BioanalyticsInstitute of Biotechnology, Technische Universität BerlinBerlinGermany
| | - Yasushi Hiraoka
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Graduate School of Frontier BiosciencesOsaka UniversitySuitaJapan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Graduate School of Frontier BiosciencesOsaka UniversitySuitaJapan
| | - Kenneth E Sawin
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
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21
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The XMAP215 Ortholog Alp14 Promotes Microtubule Nucleation in Fission Yeast. Curr Biol 2018; 28:1681-1691.e4. [PMID: 29779879 DOI: 10.1016/j.cub.2018.04.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 01/19/2018] [Accepted: 04/03/2018] [Indexed: 12/18/2022]
Abstract
The organization and number of microtubules (MTs) in a cell depend on the proper regulation of MT nucleation. Currently, the mechanism of nucleation is the most poorly understood aspect of MT dynamics. XMAP215/chTOG/Alp14/Stu2 proteins are MT polymerases that stimulate MT polymerization at MT plus ends by binding and releasing tubulin dimers. Although these proteins also localize to MT organizing centers and have nucleating activity in vitro, it is not yet clear whether these proteins participate in MT nucleation in vivo. Here, we demonstrate that in the fission yeast Schizosaccharomyces pombe, the XMAP215 ortholog Alp14 is critical for efficient MT nucleation in vivo. In multiple assays, loss of Alp14 function led to reduced nucleation rate and numbers of interphase MT bundles. Conversely, activation of Alp14 led to increased nucleation frequency. Alp14 associated with Mto1 and γ-tubulin complex components, and artificially targeting Alp14 to the γ-tubulin ring complexes (γ-TuRCs) stimulated nucleation. In imaging individual nucleation events, we found that Alp14 transiently associated with a γ-tubulin particle shortly before the appearance of a new MT. The transforming acidic coiled-coil (TACC) ortholog Alp7 mediated the localization of Alp14 at nucleation sites but not plus ends, and was required for efficient nucleation but not for MT polymerization. Our findings provide the strongest evidence to date that Alp14 serves as a critical MT nucleation factor in vivo. We suggest a model in which Alp14 associates with the γ-tubulin complex in an Alp7-dependent manner to facilitate the assembly or stabilization of the nascent MT.
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22
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Singh SK, Kumar V, Srinivasan R, Ahuja PS, Bhat SR, Sreenivasulu Y. The TRAF Mediated Gametogenesis Progression ( TRAMGaP) Gene Is Required for Megaspore Mother Cell Specification and Gametophyte Development. PLANT PHYSIOLOGY 2017; 175:1220-1237. [PMID: 28939625 PMCID: PMC5664457 DOI: 10.1104/pp.17.00275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 09/17/2017] [Indexed: 05/03/2023]
Abstract
In plants, the role of TRAF-like proteins with meprin and the TRAF homology (MATH) domain is far from clear. In animals, these proteins serve as adapter molecules to mediate signal transduction from Tumor Necrosis Factor Receptor to downstream effector molecules. A seed-sterile mutant with a disrupted TRAF-like gene (At5g26290) exhibiting aberrant gametogenesis led us to investigate the developmental role of this gene in Arabidopsis (Arabidopsis thaliana). The mutation was semidominant and resulted in pleiotropic phenotypes with such features as short siliques with fewer ovules, pollen and seed sterility, altered Megaspore Mother Cell (MMC) specification, and delayed programmed cell death in megaspores and the tapetum, features that overlapped those in other well-characterized mutants. Seed sterility and reduced transmission frequency of the mutant alleles pointed to a dual role, sporophytic and gametophytic, for the gene on the male side. The mutant also showed altered expression of various genes involved in such cellular and developmental pathways as regulation of transcription, biosynthesis and transport of lipids, hormone-mediated signaling, and gametophyte development. The diverse phenotypes of the mutant and the altered expression of key genes related to gametophyte and seed development could be explained based on the functional similarly between At5g26290 and MATH-BTB domain proteins that modulate gene expression through the ubiquitin-mediated proteasome system. These results show a novel link between a TRAF-like gene and reproductive development in plants.
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Affiliation(s)
- Sunil Kumar Singh
- Biotechnology Division, Council of Scientific and Industrial Research CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India
| | - Vajinder Kumar
- Indian Council of Agricultural Research ICAR-National Research Centre on Plant Biotechnology, New Delhi 110012, India
| | - Ramamurthy Srinivasan
- Indian Council of Agricultural Research ICAR-National Research Centre on Plant Biotechnology, New Delhi 110012, India
| | - Paramvir Singh Ahuja
- Biotechnology Division, Council of Scientific and Industrial Research CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India
| | - Shripad Ramchandra Bhat
- Indian Council of Agricultural Research ICAR-National Research Centre on Plant Biotechnology, New Delhi 110012, India
| | - Yelam Sreenivasulu
- Biotechnology Division, Council of Scientific and Industrial Research CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India
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23
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Cavanaugh AM, Jaspersen SL. Big Lessons from Little Yeast: Budding and Fission Yeast Centrosome Structure, Duplication, and Function. Annu Rev Genet 2017; 51:361-383. [PMID: 28934593 DOI: 10.1146/annurev-genet-120116-024733] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Centrosomes are a functionally conserved feature of eukaryotic cells that play an important role in cell division. The conserved γ-tubulin complex organizes spindle and astral microtubules, which, in turn, separate replicated chromosomes accurately into daughter cells. Like DNA, centrosomes are duplicated once each cell cycle. Although in some cell types it is possible for cell division to occur in the absence of centrosomes, these divisions typically result in defects in chromosome number and stability. In single-celled organisms such as fungi, centrosomes [known as spindle pole bodies (SPBs)] are essential for cell division. SPBs also must be inserted into the membrane because fungi undergo a closed mitosis in which the nuclear envelope (NE) remains intact. This poorly understood process involves events similar or identical to those needed for de novo nuclear pore complex assembly. Here, we review how analysis of fungal SPBs has advanced our understanding of centrosomes and NE events.
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Affiliation(s)
- Ann M Cavanaugh
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA;
| | - Sue L Jaspersen
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA; .,Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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24
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Sulimenko V, Hájková Z, Klebanovych A, Dráber P. Regulation of microtubule nucleation mediated by γ-tubulin complexes. PROTOPLASMA 2017; 254:1187-1199. [PMID: 28074286 DOI: 10.1007/s00709-016-1070-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/22/2016] [Indexed: 05/18/2023]
Abstract
The microtubule cytoskeleton is critically important for spatio-temporal organization of eukaryotic cells. The nucleation of new microtubules is typically restricted to microtubule organizing centers (MTOCs) and requires γ-tubulin that assembles into multisubunit complexes of various sizes. γ-Tubulin ring complexes (TuRCs) are efficient microtubule nucleators and are associated with large number of targeting, activating and modulating proteins. γ-Tubulin-dependent nucleation of microtubules occurs both from canonical MTOCs, such as spindle pole bodies and centrosomes, and additional sites such as Golgi apparatus, nuclear envelope, plasma membrane-associated sites, chromatin and surface of pre-existing microtubules. Despite many advances in structure of γ-tubulin complexes and characterization of γTuRC interacting factors, regulatory mechanisms of microtubule nucleation are not fully understood. Here, we review recent work on the factors and regulatory mechanisms that are involved in centrosomal and non-centrosomal microtubule nucleation.
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Affiliation(s)
- Vadym Sulimenko
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Zuzana Hájková
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Anastasiya Klebanovych
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Pavel Dráber
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic.
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25
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Blackwell R, Edelmaier C, Sweezy-Schindler O, Lamson A, Gergely ZR, O’Toole E, Crapo A, Hough LE, McIntosh JR, Glaser MA, Betterton MD. Physical determinants of bipolar mitotic spindle assembly and stability in fission yeast. SCIENCE ADVANCES 2017; 3:e1601603. [PMID: 28116355 PMCID: PMC5249259 DOI: 10.1126/sciadv.1601603] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 12/05/2016] [Indexed: 05/10/2023]
Abstract
Mitotic spindles use an elegant bipolar architecture to segregate duplicated chromosomes with high fidelity. Bipolar spindles form from a monopolar initial condition; this is the most fundamental construction problem that the spindle must solve. Microtubules, motors, and cross-linkers are important for bipolarity, but the mechanisms necessary and sufficient for spindle assembly remain unknown. We describe a physical model that exhibits de novo bipolar spindle formation. We began with physical properties of fission-yeast spindle pole body size and microtubule number, kinesin-5 motors, kinesin-14 motors, and passive cross-linkers. Our model results agree quantitatively with our experiments in fission yeast, thereby establishing a minimal system with which to interrogate collective self-assembly. By varying the features of our model, we identify a set of functions essential for the generation and stability of spindle bipolarity. When kinesin-5 motors are present, their bidirectionality is essential, but spindles can form in the presence of passive cross-linkers alone. We also identify characteristic failed states of spindle assembly-the persistent monopole, X spindle, separated asters, and short spindle, which are avoided by the creation and maintenance of antiparallel microtubule overlaps. Our model can guide the identification of new, multifaceted strategies to induce mitotic catastrophes; these would constitute novel strategies for cancer chemotherapy.
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Affiliation(s)
- Robert Blackwell
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
- PULS Group, Department of Physics and Cluster of Excellence: Engineering of Advanced Materials, Friedrich-Alexander University Erlangen-Nurnberg, Nagelsbachstr. 49b, Erlangen, Germany
| | | | | | - Adam Lamson
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Zachary R. Gergely
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Eileen O’Toole
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Ammon Crapo
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Loren E. Hough
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - J. Richard McIntosh
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Matthew A. Glaser
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Meredith D. Betterton
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
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26
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Toya M, Takeichi M. Organization of Non-centrosomal Microtubules in Epithelial Cells. Cell Struct Funct 2016; 41:127-135. [DOI: 10.1247/csf.16015] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Mika Toya
- RIKEN Center for Developmental Biology
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27
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Kelkar M, Martin SG. PKA antagonizes CLASP-dependent microtubule stabilization to re-localize Pom1 and buffer cell size upon glucose limitation. Nat Commun 2015; 6:8445. [PMID: 26443240 PMCID: PMC4618306 DOI: 10.1038/ncomms9445] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 08/21/2015] [Indexed: 01/28/2023] Open
Abstract
Cells couple growth with division and regulate size in response to nutrient availability. In rod-shaped fission yeast, cell-size control occurs at mitotic commitment. An important regulator is the DYRK-family kinase Pom1, which forms gradients from cell poles and inhibits the mitotic activator Cdr2, itself localized at the medial cortex. Where and when Pom1 modulates Cdr2 activity is unclear as Pom1 medial cortical levels remain constant during cell elongation. Here we show that Pom1 re-localizes to cell sides upon environmental glucose limitation, where it strongly delays mitosis. This re-localization is caused by severe microtubule destabilization upon glucose starvation, with microtubules undergoing catastrophe and depositing the Pom1 gradient nucleator Tea4 at cell sides. Microtubule destabilization requires PKA/Pka1 activity, which negatively regulates the microtubule rescue factor CLASP/Cls1/Peg1, reducing CLASP's ability to stabilize microtubules. Thus, PKA signalling tunes CLASP's activity to promote Pom1 cell side localization and buffer cell size upon glucose starvation.
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Affiliation(s)
- Manasi Kelkar
- Department of Fundamental Microbiology, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
| | - Sophie G Martin
- Department of Fundamental Microbiology, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
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28
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Borek WE, Groocock LM, Samejima I, Zou J, de Lima Alves F, Rappsilber J, Sawin KE. Mto2 multisite phosphorylation inactivates non-spindle microtubule nucleation complexes during mitosis. Nat Commun 2015; 6:7929. [PMID: 26243668 PMCID: PMC4918325 DOI: 10.1038/ncomms8929] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 06/25/2015] [Indexed: 01/09/2023] Open
Abstract
Microtubule nucleation is highly regulated during the eukaryotic cell cycle, but the underlying molecular mechanisms are largely unknown. During mitosis in fission yeast Schizosaccharomyces pombe, cytoplasmic microtubule nucleation ceases simultaneously with intranuclear mitotic spindle assembly. Cytoplasmic nucleation depends on the Mto1/2 complex, which binds and activates the γ-tubulin complex and also recruits the γ-tubulin complex to both centrosomal (spindle pole body) and non-centrosomal sites. Here we show that the Mto1/2 complex disassembles during mitosis, coincident with hyperphosphorylation of Mto2 protein. By mapping and mutating multiple Mto2 phosphorylation sites, we generate mto2-phosphomutant strains with enhanced Mto1/2 complex stability, interaction with the γ-tubulin complex and microtubule nucleation activity. A mutant with 24 phosphorylation sites mutated to alanine, mto2[24A], retains interphase-like behaviour even in mitotic cells. This provides a molecular-level understanding of how phosphorylation ‘switches off' microtubule nucleation complexes during the cell cycle and, more broadly, illuminates mechanisms regulating non-centrosomal microtubule nucleation. In S. pombe, cytoplasmic microtubule nucleation, which depends on the Mto1/2 complex, ceases during mitosis. Here, Borek et al., show that multisite phosphorylation of Mto1/2 during mitosis disassembles the Mto1/2 complex and prevents microtubule nucleation activity.
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Affiliation(s)
- Weronika E Borek
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Lynda M Groocock
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Itaru Samejima
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Juan Zou
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Flavia de Lima Alves
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Juri Rappsilber
- 1] Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK [2] Department of Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, Berlin 13355, Germany
| | - Kenneth E Sawin
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
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29
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Laporte D, Courtout F, Pinson B, Dompierre J, Salin B, Brocard L, Sagot I. A stable microtubule array drives fission yeast polarity reestablishment upon quiescence exit. J Cell Biol 2015; 210:99-113. [PMID: 26124291 PMCID: PMC4494004 DOI: 10.1083/jcb.201502025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 06/01/2015] [Indexed: 11/22/2022] Open
Abstract
Cells perpetually face the decision to proliferate or to stay quiescent. Here we show that upon quiescence establishment, Schizosaccharomyces pombe cells drastically rearrange both their actin and microtubule (MT) cytoskeletons and lose their polarity. Indeed, while polarity markers are lost from cell extremities, actin patches and cables are reorganized into actin bodies, which are stable actin filament-containing structures. Astonishingly, MTs are also stabilized and rearranged into a novel antiparallel bundle associated with the spindle pole body, named Q-MT bundle. We have identified proteins involved in this process and propose a molecular model for Q-MT bundle formation. Finally and importantly, we reveal that Q-MT bundle elongation is involved in polarity reestablishment upon quiescence exit and thereby the efficient return to the proliferative state. Our work demonstrates that quiescent S. pombe cells assemble specific cytoskeleton structures that improve the swiftness of the transition back to proliferation.
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Affiliation(s)
- Damien Laporte
- Université de Bordeaux, Institut de Biochimie et Génétique Cellulaires, 33000 Bordeaux, France Centre National de la Recherche Scientifique, UMR5095 Bordeaux, 33077 Bordeaux, France
| | - Fabien Courtout
- Université de Bordeaux, Institut de Biochimie et Génétique Cellulaires, 33000 Bordeaux, France Centre National de la Recherche Scientifique, UMR5095 Bordeaux, 33077 Bordeaux, France
| | - Benoît Pinson
- Université de Bordeaux, Institut de Biochimie et Génétique Cellulaires, 33000 Bordeaux, France Centre National de la Recherche Scientifique, UMR5095 Bordeaux, 33077 Bordeaux, France
| | - Jim Dompierre
- Université de Bordeaux, Institut de Biochimie et Génétique Cellulaires, 33000 Bordeaux, France Centre National de la Recherche Scientifique, UMR5095 Bordeaux, 33077 Bordeaux, France
| | - Bénédicte Salin
- Université de Bordeaux, Institut de Biochimie et Génétique Cellulaires, 33000 Bordeaux, France Centre National de la Recherche Scientifique, UMR5095 Bordeaux, 33077 Bordeaux, France
| | - Lysiane Brocard
- Bordeaux Imaging Center, Pôle d'imagerie du végétal, Institut National de la Recherche Agronomique, 33140 Villenave d'Ornon, France
| | - Isabelle Sagot
- Université de Bordeaux, Institut de Biochimie et Génétique Cellulaires, 33000 Bordeaux, France Centre National de la Recherche Scientifique, UMR5095 Bordeaux, 33077 Bordeaux, France
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30
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The tethering of chromatin to the nuclear envelope supports nuclear mechanics. Nat Commun 2015; 6:7159. [PMID: 26074052 PMCID: PMC4490570 DOI: 10.1038/ncomms8159] [Citation(s) in RCA: 148] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 04/10/2015] [Indexed: 12/23/2022] Open
Abstract
The nuclear lamina is thought to be the primary mechanical defence of the nucleus. However, the lamina is integrated within a network of lipids, proteins and chromatin; the interdependence of this network poses a challenge to defining the individual mechanical contributions of these components. Here, we isolate the role of chromatin in nuclear mechanics by using a system lacking lamins. Using novel imaging analyses, we observe that untethering chromatin from the inner nuclear membrane results in highly deformable nuclei in vivo, particularly in response to cytoskeletal forces. Using optical tweezers, we find that isolated nuclei lacking inner nuclear membrane tethers are less stiff than wild-type nuclei and exhibit increased chromatin flow, particularly in frequency ranges that recapitulate the kinetics of cytoskeletal dynamics. We suggest that modulating chromatin flow can define both transient and long-lived changes in nuclear shape that are biologically important and may be altered in disease. The mechanical properties of the metazoan nucleus can be influenced by the nuclear lamina. Here, Schreiner et al. show that untethering chromatin from the inner nuclear membrane results in highly deformable, softer nuclei, revealing an important role for chromatin in modulating nuclear mechanics.
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31
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Targeting of γ-tubulin complexes to microtubule organizing centers: conservation and divergence. Trends Cell Biol 2015; 25:296-307. [DOI: 10.1016/j.tcb.2014.12.002] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 11/25/2014] [Accepted: 12/01/2014] [Indexed: 11/29/2022]
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32
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Taberner N, Lof A, Roth S, Lamers D, Zeijlemaker H, Dogterom M. In vitro systems for the study of microtubule-based cell polarity in fission yeast. Methods Cell Biol 2015; 128:1-22. [DOI: 10.1016/bs.mcb.2015.02.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
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33
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Fahmy K, Akber M, Cai X, Koul A, Hayder A, Baumgartner S. αTubulin 67C and Ncd are essential for establishing a cortical microtubular network and formation of the Bicoid mRNA gradient in Drosophila. PLoS One 2014; 9:e112053. [PMID: 25390693 DOI: 10.1371/journal.pone.0112053] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 10/10/2014] [Indexed: 11/18/2022] Open
Abstract
The Bicoid (Bcd) protein gradient in Drosophila serves as a paradigm for gradient formation in textbooks. To explain the generation of the gradient, the ARTS model, which is based on the observation of a bcd mRNA gradient, proposes that the bcd mRNA, localized at the anterior pole at fertilization, migrates along microtubules (MTs) at the cortex to the posterior to form a bcd mRNA gradient which is translated to form a protein gradient. To fulfil the criteria of the ARTS model, an early cortical MT network is thus a prerequisite. We report hitherto undiscovered MT activities in the early embryo important for bcd mRNA transport: (i) an early and omnidirectional MT network exclusively at the anterior cortex of early nuclear cycle embryos showing activity during metaphase and anaphase only, (ii) long MTs up to 50 µm extending into the yolk at blastoderm stage to enable basal-apical transport. The cortical MT network is not anchored to the actin cytoskeleton. The posterior transport of the mRNA via the cortical MT network critically depends on maternally-expressed αTubulin67C and the minus-end motor Ncd. In either mutant, cortical transport of the bcd mRNA does not take place and the mRNA migrates along another yet undisclosed interior MT network, instead. Our data strongly corroborate the ARTS model and explain the occurrence of the bcd mRNA gradient.
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Affiliation(s)
- Khalid Fahmy
- Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Mira Akber
- Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Xiaoli Cai
- Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Aabid Koul
- Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Awais Hayder
- Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Stefan Baumgartner
- Department of Experimental Medical Sciences, Lund University, Lund, Sweden
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34
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The kinetochore protein Kis1/Eic1/Mis19 ensures the integrity of mitotic spindles through maintenance of kinetochore factors Mis6/CENP-I and CENP-A. PLoS One 2014; 9:e111905. [PMID: 25375240 PMCID: PMC4222959 DOI: 10.1371/journal.pone.0111905] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 10/06/2014] [Indexed: 12/14/2022] Open
Abstract
Microtubules play multiple roles in a wide range of cellular phenomena, including cell polarity establishment and chromosome segregation. A number of microtubule regulators have been identified, including microtubule-associated proteins and kinases, and knowledge of these factors has contributed to our molecular understanding of microtubule regulation of each relevant cellular process. The known regulators, however, are insufficient to explain how those processes are linked to one another, underscoring the need to identify additional regulators. To find such novel mechanisms and microtubule regulators, we performed a screen that combined genetics and microscopy for fission yeast mutants defective in microtubule organization. We isolated approximately 900 mutants showing defects in either microtubule organization or the nuclear envelope, and these mutants were classified into 12 categories. We particularly focused on one mutant, kis1, which displayed spindle defects in early mitosis. The kis1 mutant frequently failed to assemble a normal bipolar spindle. The responsible gene encoded a kinetochore protein, Mis19 (also known as Eic1), which localized to the interface of kinetochores and spindle poles. We also found that the inner kinetochore proteins Mis6/CENP-I and Cnp1/CENP-A were delocalized from kinetochores in the kis1 cells and that kinetochore-microtubule attachment was defective. Another mutant, mis6, also displayed similar spindle defects. We conclude that Kis1 is required for inner kinetochore organization, through which Kis1 ensures kinetochore-microtubule attachment and spindle integrity. Thus, we propose an unexpected relationship between inner kinetochore organization and spindle integrity.
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35
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Pöhlmann J, Risse C, Seidel C, Pohlmann T, Jakopec V, Walla E, Ramrath P, Takeshita N, Baumann S, Feldbrügge M, Fischer R, Fleig U. The Vip1 inositol polyphosphate kinase family regulates polarized growth and modulates the microtubule cytoskeleton in fungi. PLoS Genet 2014; 10:e1004586. [PMID: 25254656 PMCID: PMC4177672 DOI: 10.1371/journal.pgen.1004586] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 07/08/2014] [Indexed: 11/19/2022] Open
Abstract
Microtubules (MTs) are pivotal for numerous eukaryotic processes ranging from cellular morphogenesis, chromosome segregation to intracellular transport. Execution of these tasks requires intricate regulation of MT dynamics. Here, we identify a new regulator of the Schizosaccharomyces pombe MT cytoskeleton: Asp1, a member of the highly conserved Vip1 inositol polyphosphate kinase family. Inositol pyrophosphates generated by Asp1 modulate MT dynamic parameters independent of the central +TIP EB1 and in a dose-dependent and cellular-context-dependent manner. Importantly, our analysis of the in vitro kinase activities of various S. pombe Asp1 variants demonstrated that the C-terminal phosphatase-like domain of the dual domain Vip1 protein negatively affects the inositol pyrophosphate output of the N-terminal kinase domain. These data suggest that the former domain has phosphatase activity. Remarkably, Vip1 regulation of the MT cytoskeleton is a conserved feature, as Vip1-like proteins of the filamentous ascomycete Aspergillus nidulans and the distantly related pathogenic basidiomycete Ustilago maydis also affect the MT cytoskeleton in these organisms. Consistent with the role of interphase MTs in growth zone selection/maintenance, all 3 fungal systems show aspects of aberrant cell morphogenesis. Thus, for the first time we have identified a conserved biological process for inositol pyrophosphates.
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Affiliation(s)
- Jennifer Pöhlmann
- Lehrstuhl für funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Carmen Risse
- Lehrstuhl für funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Constanze Seidel
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Karlsruhe, Germany
| | - Thomas Pohlmann
- Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Visnja Jakopec
- Lehrstuhl für funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Eva Walla
- Lehrstuhl für funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Pascal Ramrath
- Lehrstuhl für funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Norio Takeshita
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Karlsruhe, Germany
- University of Tsukuba, Faculty of Life and Environmental Sciences, Ibaraki, Tsukuba, Japan
| | - Sebastian Baumann
- Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Michael Feldbrügge
- Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Reinhard Fischer
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Karlsruhe, Germany
| | - Ursula Fleig
- Lehrstuhl für funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
- * E-mail:
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36
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Swartz RK, Rodriguez EC, King MC. A role for nuclear envelope-bridging complexes in homology-directed repair. Mol Biol Cell 2014; 25:2461-71. [PMID: 24943839 PMCID: PMC4142617 DOI: 10.1091/mbc.e13-10-0569] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Persistent double-strand DNA breaks (DSBs) are recruited to the nuclear periphery, where they induce formation of associated nuclear envelope–spanning LINC complexes made up of the SUN protein Sad1 and the KASH protein Kms1. The LINC complex couples DSBs within the nucleus to cytoplasmic microtubules, which alters DSB repair pathway choice. Unless efficiently and faithfully repaired, DNA double-strand breaks (DSBs) cause genome instability. We implicate a Schizosaccharomyces pombe nuclear envelope–spanning linker of nucleoskeleton and cytoskeleton (LINC) complex, composed of the Sad1/Unc84 protein Sad1 and Klarsicht/Anc1/SYNE1 homology protein Kms1, in the repair of DSBs. An induced DSB associates with Sad1 and Kms1 in S/G2 phases of the cell cycle, connecting the DSB to cytoplasmic microtubules. DSB resection to generate single-stranded DNA and the ATR kinase drive the formation of Sad1 foci in response to DNA damage. Depolymerization of microtubules or loss of Kms1 leads to an increase in the number and size of DSB-induced Sad1 foci. Further, Kms1 and the cytoplasmic microtubule regulator Mto1 promote the repair of an induced DSB by gene conversion, a type of homology-directed repair. kms1 genetically interacts with a number of genes involved in homology-directed repair; these same gene products appear to attenuate the formation or promote resolution of DSB-induced Sad1 foci. We suggest that the connection of DSBs with the cytoskeleton through the LINC complex may serve as an input to repair mechanism choice and efficiency.
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Affiliation(s)
- Rebecca K Swartz
- Department of Cell Biology, Yale School of Medicine, New Haven, CT -06520
| | - Elisa C Rodriguez
- Department of Cell Biology, Yale School of Medicine, New Haven, CT -06520
| | - Megan C King
- Department of Cell Biology, Yale School of Medicine, New Haven, CT -06520
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37
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Carlier-Grynkorn F, Ji L, Fraisier V, Lombard B, Dingli F, Loew D, Paoletti A, Ronot X, Tran PT. Fission yeast mtr1p regulates interphase microtubule cortical dwell-time. Biol Open 2014; 3:591-6. [PMID: 24928430 PMCID: PMC4154295 DOI: 10.1242/bio.20148607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The microtubule cytoskeleton plays important roles in cell polarity, motility and division. Microtubules inherently undergo dynamic instability, stochastically switching between phases of growth and shrinkage. In cells, some microtubule-associated proteins (MAPs) and molecular motors can further modulate microtubule dynamics. We present here the fission yeast mtr1(+), a new regulator of microtubule dynamics that appears to be not a MAP or a motor. mtr1-deletion (mtr1Δ) primarily results in longer microtubule dwell-time at the cell tip cortex, suggesting that mtr1p acts directly or indirectly as a destabilizer of microtubules. mtr1p is antagonistic to mal3p, the ortholog of mammalian EB1, which stabilizes microtubules. mal3Δ results in short microtubules, but can be partially rescued by mtr1Δ, as the double mutant mal3Δ mtr1Δ exhibits longer microtubules than mal3Δ single mutant. By sequence homology, mtr1p is predicted to be a component of the ribosomal quality control complex. Intriguingly, deletion of a predicted ribosomal gene, rps1801, also resulted in longer microtubule dwell-time similar to mtr1Δ. The double-mutant mal3Δ rps1801Δ also exhibits longer microtubules than mal3Δ single mutant alone. Our study suggests a possible involvement of mtr1p and the ribosome complex in modulating microtubule dynamics.
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Affiliation(s)
| | - Liang Ji
- Institut Curie, Paris 75005, France CNRS, UMR 144, Paris 75005, France
| | - Vincent Fraisier
- Institut Curie, Paris 75005, France CNRS, UMR 144, Paris 75005, France
| | | | | | | | - Anne Paoletti
- Institut Curie, Paris 75005, France CNRS, UMR 144, Paris 75005, France
| | - Xavier Ronot
- Laboratoire CaCyS, FRE AGIM 3405 UJF-CNRS-EPHE-UMPF, La Tronche 38700, France
| | - Phong T Tran
- Institut Curie, Paris 75005, France CNRS, UMR 144, Paris 75005, France Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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38
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Yamamoto A. Gathering up meiotic telomeres: a novel function of the microtubule-organizing center. Cell Mol Life Sci 2014; 71:2119-34. [PMID: 24413667 PMCID: PMC11113538 DOI: 10.1007/s00018-013-1548-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/12/2013] [Accepted: 12/19/2013] [Indexed: 11/26/2022]
Abstract
During meiosis, telomeres cluster and promote homologous chromosome pairing. Telomere clustering depends on conserved SUN and KASH domain nuclear membrane proteins, which form a complex called the linker of nucleoskeleton and cytoskeleton (LINC) and connect telomeres with the cytoskeleton. It has been thought that LINC-mediated cytoskeletal forces induce telomere clustering. However, how cytoskeletal forces induce telomere clustering is not fully understood. Recent study of fission yeast has shown that the LINC complex forms the microtubule-organizing center (MTOC) at the telomere, which has been designated as the "telocentrosome", and that microtubule motors gather telomeres via telocentrosome-nucleated microtubules. This MTOC-dependent telomere clustering might be conserved in other eukaryotes. Furthermore, the MTOC-dependent clustering mechanism appears to function in various other biological events. This review presents an overview of the current understanding of the mechanism of meiotic telomere clustering and discusses the universality of the MTOC-dependent clustering mechanism.
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Affiliation(s)
- Ayumu Yamamoto
- Department of Chemistry, Graduate School of Science, Shizuoka University, 836 Ohya, Suruga-ku, Sizuoka, 422-8529, Japan,
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39
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Lynch EM, Groocock LM, Borek WE, Sawin KE. Activation of the γ-tubulin complex by the Mto1/2 complex. Curr Biol 2014; 24:896-903. [PMID: 24704079 PMCID: PMC3989768 DOI: 10.1016/j.cub.2014.03.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 02/17/2014] [Accepted: 03/04/2014] [Indexed: 11/19/2022]
Abstract
The multisubunit γ-tubulin complex (γ-TuC) is critical for microtubule nucleation in eukaryotic cells, but it remains unclear how the γ-TuC becomes active specifically at microtubule-organizing centers (MTOCs) and not more broadly throughout the cytoplasm. In the fission yeast Schizosaccharomyces pombe, the proteins Mto1 and Mto2 form the Mto1/2 complex, which interacts with the γ-TuC and recruits it to several different types of cytoplasmic MTOC sites. Here, we show that the Mto1/2 complex activates γ-TuC-dependent microtubule nucleation independently of localizing the γ-TuC. This was achieved through the construction of a "minimal" version of Mto1/2, Mto1/2[bonsai], that does not localize to any MTOC sites. By direct imaging of individual Mto1/2[bonsai] complexes nucleating single microtubules in vivo, we further determine the number and stoichiometry of Mto1, Mto2, and γ-TuC subunits Alp4 (GCP2) and Alp6 (GCP3) within active nucleation complexes. These results are consistent with active nucleation complexes containing ∼13 copies each of Mto1 and Mto2 per active complex and likely equimolar amounts of γ-tubulin. Additional experiments suggest that Mto1/2 multimers act to multimerize the fission yeast γ-tubulin small complex and that multimerization of Mto2 in particular may underlie assembly of active microtubule nucleation complexes.
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Affiliation(s)
- Eric M Lynch
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Swann Building, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Lynda M Groocock
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Swann Building, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Weronika E Borek
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Swann Building, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Kenneth E Sawin
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Swann Building, Mayfield Road, Edinburgh EH9 3JR, UK.
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40
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Abstract
Microtubules exhibit dynamic instability, stochastically switching between infrequent phases of growth and shrinkage. In the cell, microtubule dynamic instability is further modulated by microtubule-associated proteins and motors, which are specifically tuned to cell cycle stages. For example, mitotic microtubules are more dynamic than interphase microtubules. The different parameters of microtubule dynamics can be measured from length versus time data, which are generally obtained from time-lapse acquisition using the optical microscope. The typical maximum resolution of the optical microscope is ~λ/2 or ~300 nm. This scale represents a challenge for imaging fission yeast microtubule dynamics specifically during early mitosis, where the bipolar mitotic spindle contains many short dynamic microtubules of ~1-μm scale. Here, we present a novel method to image short fission yeast mitotic microtubules. The method uses the thermosensitive reversible kinesin-5 cut7.24(ts) to create monopolar spindles, where asters of individual mitotic microtubules are presented for imaging and subsequent analysis.
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41
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Martin SG, Arkowitz RA. Cell polarization in budding and fission yeasts. FEMS Microbiol Rev 2014; 38:228-53. [DOI: 10.1111/1574-6976.12055] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 11/13/2013] [Accepted: 12/03/2013] [Indexed: 11/30/2022] Open
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42
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Kloc M, Kubiak JZ, Li XC, Ghobrial RM. The newly found functions of MTOC in immunological response. J Leukoc Biol 2013; 95:417-30. [DOI: 10.1189/jlb.0813468] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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43
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Dhani DK, Goult BT, George GM, Rogerson DT, Bitton DA, Miller CJ, Schwabe JWR, Tanaka K. Mzt1/Tam4, a fission yeast MOZART1 homologue, is an essential component of the γ-tubulin complex and directly interacts with GCP3(Alp6). Mol Biol Cell 2013; 24:3337-49. [PMID: 24006493 PMCID: PMC3814152 DOI: 10.1091/mbc.e13-05-0253] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 07/22/2013] [Accepted: 08/29/2013] [Indexed: 11/25/2022] Open
Abstract
In humans, MOZART1 plays an essential role in mitotic spindle formation as a component of the γ-tubulin ring complex. We report that the fission yeast homologue of MOZART1, Mzt1/Tam4, is located at microtubule-organizing centers (MTOCs) and coimmunoprecipitates with γ-tubulin Gtb1 from cell extracts. We show that mzt1/tam4 is an essential gene in fission yeast, encoding a 64-amino acid peptide, depletion of which leads to aberrant microtubule structure, including malformed mitotic spindles and impaired interphase microtubule array. Mzt1/Tam4 depletion also causes cytokinesis defects, suggesting a role of the γ-tubulin complex in the regulation of cytokinesis. Yeast two-hybrid analysis shows that Mzt1/Tam4 forms a complex with Alp6, a fission yeast homologue of γ-tubulin complex protein 3 (GCP3). Biophysical methods demonstrate that there is a direct interaction between recombinant Mzt1/Tam4 and the N-terminal region of GCP3(Alp6). Together our results suggest that Mzt1/Tam4 contributes to the MTOC function through regulation of GCP3(Alp6).
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Affiliation(s)
- Deepsharan K. Dhani
- Department of Biochemistry, University of Leicester, Leicester LE1 9HN, United Kingdom
| | - Benjamin T. Goult
- Department of Biochemistry, University of Leicester, Leicester LE1 9HN, United Kingdom
| | - Gifty M. George
- Department of Biochemistry, University of Leicester, Leicester LE1 9HN, United Kingdom
| | - Daniel T. Rogerson
- Department of Biochemistry, University of Leicester, Leicester LE1 9HN, United Kingdom
| | - Danny A. Bitton
- Paterson Institute for Cancer Research, University of Manchester, Manchester M20 4BX, United Kingdom
| | - Crispin J. Miller
- Paterson Institute for Cancer Research, University of Manchester, Manchester M20 4BX, United Kingdom
| | - John W. R. Schwabe
- Department of Biochemistry, University of Leicester, Leicester LE1 9HN, United Kingdom
| | - Kayoko Tanaka
- Department of Biochemistry, University of Leicester, Leicester LE1 9HN, United Kingdom
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44
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Masuda H, Mori R, Yukawa M, Toda T. Fission yeast MOZART1/Mzt1 is an essential γ-tubulin complex component required for complex recruitment to the microtubule organizing center, but not its assembly. Mol Biol Cell 2013; 24:2894-906. [PMID: 23885124 PMCID: PMC3771951 DOI: 10.1091/mbc.e13-05-0235] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 07/05/2013] [Accepted: 07/11/2013] [Indexed: 12/13/2022] Open
Abstract
γ-Tubulin plays a universal role in microtubule nucleation from microtubule organizing centers (MTOCs) such as the animal centrosome and fungal spindle pole body (SPB). γ-Tubulin functions as a multiprotein complex called the γ-tubulin complex (γ-TuC), consisting of GCP1-6 (GCP1 is γ-tubulin). In fungi and flies, it has been shown that GCP1-3 are core components, as they are indispensable for γ-TuC complex assembly and cell division, whereas the other three GCPs are not. Recently a novel conserved component, MOZART1, was identified in humans and plants, but its precise functions remain to be determined. In this paper, we characterize the fission yeast homologue Mzt1, showing that it is essential for cell viability. Mzt1 is present in approximately equal stoichiometry with Alp4/GCP2 and localizes to all the MTOCs, including the SPB and interphase and equatorial MTOCs. Temperature-sensitive mzt1 mutants display varying degrees of compromised microtubule organization, exhibiting multiple defects during both interphase and mitosis. Mzt1 is required for γ-TuC recruitment, but not sufficient to localize to the SPB, which depends on γ-TuC integrity. Intriguingly, the core γ-TuC assembles in the absence of Mzt1. Mzt1 therefore plays a unique role within the γ-TuC components in attachment of this complex to the major MTOC site.
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Affiliation(s)
- Hirohisa Masuda
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3LY, United Kingdom
| | - Risa Mori
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3LY, United Kingdom
| | - Masashi Yukawa
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3LY, United Kingdom
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Takashi Toda
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3LY, United Kingdom
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45
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Kim KD, Tanizawa H, Iwasaki O, Corcoran CJ, Capizzi JR, Hayden JE, Noma KI. Centromeric motion facilitates the mobility of interphase genomic regions in fission yeast. J Cell Sci 2013; 126:5271-83. [PMID: 23986481 DOI: 10.1242/jcs.133678] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Dispersed genetic elements, such as retrotransposons and Pol-III-transcribed genes, including tRNA and 5S rRNA, cluster and associate with centromeres in fission yeast through the function of condensin. However, the dynamics of these condensin-mediated genomic associations remains unknown. We have examined the 3D motions of genomic loci including the centromere, telomere, rDNA repeat locus, and the loci carrying Pol-III-transcribed genes or long-terminal repeat (LTR) retrotransposons in live cells at as short as 1.5-second intervals. Treatment with carbendazim (CBZ), a microtubule-destabilizing agent, not only prevents centromeric motion, but also reduces the mobility of the other genomic loci during interphase. Further analyses demonstrate that condensin-mediated associations between centromeres and the genomic loci are clonal, infrequent and transient. However, when associated, centromeres and the genomic loci migrate together in a coordinated fashion. In addition, a condensin mutation that disrupts associations between centromeres and the genomic loci results in a concomitant decrease in the mobility of the loci. Our study suggests that highly mobile centromeres pulled by microtubules in cytoplasm serve as 'genome mobility elements' by facilitating physical relocations of associating genomic regions.
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Affiliation(s)
- Kyoung-Dong Kim
- The Wistar Institute, Spruce Street, Philadelphia, PA 19104, USA
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46
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Electron tomography reveals novel microtubule lattice and microtubule organizing centre defects in +TIP mutants. PLoS One 2013; 8:e61698. [PMID: 23613905 PMCID: PMC3627915 DOI: 10.1371/journal.pone.0061698] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 03/17/2013] [Indexed: 12/31/2022] Open
Abstract
Mal3p and Tip1p are the fission yeast (Schizosaccharomyces pombe) homologues of EB1 and CLIP-170, two conserved microtubule plus end tracking proteins (+TIPs). These proteins are crucial regulators of microtubule dynamics. Using electron tomography, we carried out a high-resolution analysis of the phenotypes caused by mal3 and tip1 deletions. We describe the 3-dimensional microtubule organization, quantify microtubule end structures and uncover novel defects of the microtubule lattices. We also reveal unexpected structural modifications of the spindle pole bodies (SPBs), the yeast microtubule organizing centers. In both mutants we observe an increased SPB volume and a reduced number of MT/SPB attachments. The discovered defects alter previous interpretations of the mutant phenotypes and provide new insights into the molecular functions of the two protein families.
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47
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Bouxsein NF, Carroll-Portillo A, Bachand M, Sasaki DY, Bachand GD. A continuous network of lipid nanotubes fabricated from the gliding motility of kinesin powered microtubule filaments. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:2992-2999. [PMID: 23391254 DOI: 10.1021/la304238u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Synthetic interconnected lipid nanotube networks were fabricated on the millimeter scale based on the simple, cooperative interaction between phospholipid vesicles and kinesin-microtubule (MT) transport systems. More specifically, taxol-stabilized MTs, in constant 2D motion via surface absorbed kinesin, extracted and extended lipid nanotube networks from large Lα phase multilamellar liposomes (5-25 μm). Based on the properties of the inverted motility geometry, the total size of these nanofluidic networks was limited by MT surface density, molecular motor energy source (ATP), and total amount and physical properties of lipid source material. Interactions between MTs and extended lipid nanotubes resulted in bifurcation of the nanotubes and ultimately the generation of highly branched networks of fluidically connected nanotubes. The network bifurcation was easily tuned by changing the density of microtubules on the surface to increase or decrease the frequency of branching. The ability of these networks to capture nanomaterials at the membrane surface with high fidelity was subsequently demonstrated using quantum dots as a model system. The diffusive transport of quantum dots was also characterized with respect to using these nanotube networks for mass transport applications.
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Affiliation(s)
- Nathan F Bouxsein
- Center for Integrated Nanotechnology, Sandia National Laboratories, Albuquerque, New Mexico 87123, USA
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48
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Duellberg C, Fourniol FJ, Maurer SP, Roostalu J, Surrey T. End-binding proteins and Ase1/PRC1 define local functionality of structurally distinct parts of the microtubule cytoskeleton. Trends Cell Biol 2013; 23:54-63. [PMID: 23103209 DOI: 10.1016/j.tcb.2012.10.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 09/25/2012] [Accepted: 10/02/2012] [Indexed: 12/27/2022]
Abstract
The microtubule cytoskeleton is crucial for the intracellular organization of eukaryotic cells. It is a dynamic scaffold that has to perform a variety of very different functions. This multitasking is achieved through the activity of numerous microtubule-associated proteins. Two prominent classes of proteins are central to the selective recognition of distinct transiently existing structural features of the microtubule cytoskeleton. They define local functionality through tightly regulated protein recruitment. Here we summarize the recent developments in elucidating the molecular mechanism underlying the action of microtubule end-binding proteins (EBs) and antiparallel microtubule crosslinkers of the Ase1/PRC1 family that represent the core of these two recruitment modules. Despite their fundamentally different activities, these conserved families share several common features.
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Affiliation(s)
- Christian Duellberg
- London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
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49
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Juranić M, Srilunchang KO, Krohn NG, Leljak-Levanić D, Sprunck S, Dresselhaus T. Germline-specific MATH-BTB substrate adaptor MAB1 regulates spindle length and nuclei identity in maize. THE PLANT CELL 2012; 24:4974-91. [PMID: 23250449 PMCID: PMC3556970 DOI: 10.1105/tpc.112.107169] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 11/05/2012] [Accepted: 11/28/2012] [Indexed: 05/03/2023]
Abstract
Germline and early embryo development constitute ideal model systems to study the establishment of polarity, cell identity, and asymmetric cell divisions (ACDs) in plants. We describe here the function of the MATH-BTB domain protein MAB1 that is exclusively expressed in the germ lineages and the zygote of maize (Zea mays). mab1 (RNA interference [RNAi]) mutant plants display chromosome segregation defects and short spindles during meiosis that cause insufficient separation and migration of nuclei. After the meiosis-to-mitosis transition, two attached nuclei of similar identity are formed in mab1 (RNAi) mutants leading to an arrest of further germline development. Transient expression studies of MAB1 in tobacco (Nicotiana tabacum) Bright Yellow-2 cells revealed a cell cycle-dependent nuclear localization pattern but no direct colocalization with the spindle apparatus. MAB1 is able to form homodimers and interacts with the E3 ubiquitin ligase component Cullin 3a (CUL3a) in the cytoplasm, likely as a substrate-specific adapter protein. The microtubule-severing subunit p60 of katanin was identified as a candidate substrate for MAB1, suggesting that MAB1 resembles the animal key ACD regulator Maternal Effect Lethal 26 (MEL-26). In summary, our findings provide further evidence for the importance of posttranslational regulation for asymmetric divisions and germline progression in plants and identified an unstable key protein that seems to be involved in regulating the stability of a spindle apparatus regulator(s).
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Affiliation(s)
- Martina Juranić
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053 Regensburg, Germany
- Department of Molecular Biology, Faculty of Science and Mathematics, University of Zagreb, 10000 Zagreb, Croatia
| | | | - Nádia Graciele Krohn
- Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirao Preto 14040-903, Brazil
| | - Dunja Leljak-Levanić
- Department of Molecular Biology, Faculty of Science and Mathematics, University of Zagreb, 10000 Zagreb, Croatia
| | - Stefanie Sprunck
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053 Regensburg, Germany
| | - Thomas Dresselhaus
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053 Regensburg, Germany
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50
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Al-Bassam J, Kim H, Flor-Parra I, Lal N, Velji H, Chang F. Fission yeast Alp14 is a dose-dependent plus end-tracking microtubule polymerase. Mol Biol Cell 2012; 23:2878-90. [PMID: 22696680 PMCID: PMC3408415 DOI: 10.1091/mbc.e12-03-0205] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Alp14, a XMAP215 orthologue in fission yeast, is a microtubule (MT) polymerase. It tracks growing MT plus ends and regulates the polymerization state of tubulin by cycling between a tubulin dimer–bound cytoplasmic state and a MT polymerase state that promotes rapid MT assembly. XMAP215/Dis1 proteins are conserved tubulin-binding TOG-domain proteins that regulate microtubule (MT) plus-end dynamics. Here we show that Alp14, a XMAP215 orthologue in fission yeast, Schizosaccharomyces pombe, has properties of a MT polymerase. In vivo, Alp14 localizes to growing MT plus ends in a manner independent of Mal3 (EB1). alp14-null mutants display short interphase MTs with twofold slower assembly rate and frequent pauses. Alp14 is a homodimer that binds a single tubulin dimer. In vitro, purified Alp14 molecules track growing MT plus ends and accelerate MT assembly threefold. TOG-domain mutants demonstrate that tubulin binding is critical for function and plus end localization. Overexpression of Alp14 or only its TOG domains causes complete MT loss in vivo, and high Alp14 concentration inhibits MT assembly in vitro. These inhibitory effects may arise from Alp14 sequestration of tubulin and effects on the MT. Our studies suggest that Alp14 regulates the polymerization state of tubulin by cycling between a tubulin dimer–bound cytoplasmic state and a MT polymerase state that promotes rapid MT assembly.
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Affiliation(s)
- Jawdat Al-Bassam
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA.
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