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Ozaki K, Chikashige Y, Hiraoka Y, Matsumoto T. Fission yeast Scp3 potentially maintains microtubule orientation through bundling. PLoS One 2015; 10:e0120109. [PMID: 25767875 PMCID: PMC4359140 DOI: 10.1371/journal.pone.0120109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 01/19/2015] [Indexed: 11/19/2022] Open
Abstract
Microtubules play important roles in organelle transport, the maintenance of cell polarity and chromosome segregation and generally form bundles during these processes. The fission yeast gene scp3+ was identified as a multicopy suppressor of the cps3-81 mutant, which is hypersensitive to isopropyl N-3-chlorophenylcarbamate (CIPC), a poison that induces abnormal multipolar spindle formation in higher eukaryotes. In this study, we investigated the function of Scp3 along with the effect of CIPC in the fission yeast Schizosaccharomyces pombe. Microscopic observation revealed that treatment with CIPC, cps3-81 mutation and scp3+ gene deletion disturbed the orientation of microtubules in interphase cells. Overexpression of scp3+ suppressed the abnormal orientation of microtubules by promoting bundling. Functional analysis suggested that Scp3 functions independently from Ase1, a protein largely required for the bundling of the mitotic spindle. A strain lacking the ase1+ gene was more sensitive to CIPC, with the drug affecting the integrity of the mitotic spindle, indicating that CIPC has a mitotic target that has a role redundant with Ase1. These results suggested that multiple systems are independently involved to ensure microtubule orientation by bundling in fission yeast.
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Affiliation(s)
- Kanako Ozaki
- Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto, Japan
| | - Yuji Chikashige
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Hyogo, Japan
| | - Yasushi Hiraoka
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Hyogo, Japan
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Tomohiro Matsumoto
- Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto, Japan
- Radiation Biology Center, Kyoto University, Kyoto, Kyoto, Japan
- * E-mail:
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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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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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Funaya C, Samarasinghe S, Pruggnaller S, Ohta M, Connolly Y, Müller J, Murakami H, Grallert A, Yamamoto M, Smith D, Antony C, Tanaka K. Transient structure associated with the spindle pole body directs meiotic microtubule reorganization in S. pombe. Curr Biol 2012; 22:562-74. [PMID: 22425159 PMCID: PMC3382715 DOI: 10.1016/j.cub.2012.02.042] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 02/10/2012] [Accepted: 02/17/2012] [Indexed: 02/06/2023]
Abstract
Background Vigorous chromosome movements driven by cytoskeletal assemblies are a widely conserved feature of sexual differentiation to facilitate meiotic recombination. In fission yeast, this process involves the dramatic conversion of arrays of cytoplasmic microtubules (MTs), generated from multiple MT organizing centers (MTOCs), into a single radial MT (rMT) array associated with the spindle pole body (SPB), the major MTOC during meiotic prophase. The rMT is then dissolved upon the onset of meiosis I when a bipolar spindle emerges to conduct chromosome segregation. Structural features and molecular mechanisms that govern these dynamic MT rearrangements are poorly understood. Results Electron tomography of the SPBs showed that the rMT emanates from a newly recognized amorphous structure, which we term the rMTOC. The rMTOC, which resides at the cytoplasmic side of the SPB, is highly enriched in γ-tubulin reminiscent of the pericentriolar material of higher eukaryotic centrosomes. Formation of the rMTOC depends on Hrs1/Mcp6, a meiosis-specific SPB component that is located at the rMTOC. At the onset of meiosis I, Hrs1/Mcp6 is subject to strict downregulation by both proteasome-dependent degradation and phosphorylation leading to complete inactivation of the rMTOC. This ensures rMT dissolution and bipolar spindle formation. Conclusions Our study reveals the molecular basis for the transient generation of a novel MTOC, which triggers a program of MT rearrangement that is required for meiotic differentiation.
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Affiliation(s)
- Charlotta Funaya
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
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Iimori M, Ozaki K, Chikashige Y, Habu T, Hiraoka Y, Maki T, Hayashi I, Obuse C, Matsumoto T. A mutation of the fission yeast EB1 overcomes negative regulation by phosphorylation and stabilizes microtubules. Exp Cell Res 2012; 318:262-75. [DOI: 10.1016/j.yexcr.2011.11.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2011] [Revised: 10/05/2011] [Accepted: 11/09/2011] [Indexed: 11/16/2022]
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Masuda H, Fong CS, Ohtsuki C, Haraguchi T, Hiraoka Y. Spatiotemporal regulations of Wee1 at the G2/M transition. Mol Biol Cell 2011; 22:555-69. [PMID: 21233285 PMCID: PMC3046054 DOI: 10.1091/mbc.e10-07-0644] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Wee1 is highly dynamic at the SPB during the G2/M transition. Wee1 accumulates at the nuclear face of the SPB when cyclin B–Cdc2 peaks at the SPB and disappears from the SPB during spindle assembly. This dynamic behavior of Wee1 at the SPB is important for regulation of cyclin B–Cdc2 activity and proper mitotic entry and progression. Wee1 is a protein kinase that negatively regulates mitotic entry in G2 phase by suppressing cyclin B–Cdc2 activity, but its spatiotemporal regulations remain to be elucidated. We observe the dynamic behavior of Wee1 in Schizosaccharomyces pombe cells and manipulate its localization and kinase activity to study its function. At late G2, nuclear Wee1 efficiently suppresses cyclin B–Cdc2 around the spindle pole body (SPB). During the G2/M transition when cyclin B–Cdc2 is highly enriched at the SPB, Wee1 temporally accumulates at the nuclear face of the SPB in a cyclin B–Cdc2-dependent manner and locally suppresses both cyclin B–Cdc2 activity and spindle assembly to counteract a Polo kinase–dependent positive feedback loop. Then Wee1 disappears from the SPB during spindle assembly. We propose that regulation of Wee1 localization around the SPB during the G2/M transition is important for proper mitotic entry and progression.
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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.
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Abstract
During the cell cycle of the fission yeast Schizosaccharomyces pombe, striking changes in the organization of the cytoplasmic microtubule cytoskeleton take place. These may serve as a model for understanding the different modes of microtubule organization that are often characteristic of differentiated higher eukaryotic cells. In the last few years, considerable progress has been made in our understanding of the organization and behaviour of fission yeast cytoplasmic microtubules, not only in the identification of the genes and proteins involved but also in the physiological analysis of function using fluorescently-tagged proteins in vivo. In this review we discuss the state of our knowledge in three areas: microtubule nucleation, regulation of microtubule dynamics and the organization and polarity of microtubule bundles. Advances in these areas provide a solid framework for a more detailed understanding of cytoplasmic microtubule organization.
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Affiliation(s)
- Kenneth E Sawin
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Swann Building, Mayfield Road, Edinburgh EH9 3JR, UK.
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Current awareness on yeast. Yeast 2006. [DOI: 10.1002/yea.1319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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