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Yao C, Wang C, Li Y, Zavortink M, Archambault V, Girton J, Johansen KM, Johansen J. Evidence for a role of spindle matrix formation in cell cycle progression by antibody perturbation. PLoS One 2018; 13:e0208022. [PMID: 30485354 PMCID: PMC6261614 DOI: 10.1371/journal.pone.0208022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 11/11/2018] [Indexed: 12/27/2022] Open
Abstract
In Drosophila it has recently been demonstrated that a spindle matrix in the form of a membrane-less macromolecular assembly embeds the microtubule-based spindle apparatus. In addition, two of its constituents, Megator and Chromator, were shown to function as spatial regulators of spindle checkpoint proteins. However, whether the spindle matrix plays a wider functional role in spatially regulating cell cycle progression factors was unknown. Here using a live imaging approach we provide evidence that a number of key cell cycle proteins such as Cyclin B, Polo, and Ran co-localize with the spindle matrix during mitosis. Furthermore, prevention of spindle matrix formation by injection of a function blocking antibody against the spindle matrix protein Chromator results in cell cycle arrest prior to nuclear envelope breakdown. In such embryos the spatial dynamics of Polo and Cyclin B enrichment at the nuclear rim and kinetochores is abrogated and Polo is not imported into the nucleus. This is in contrast to colchicine-arrested embryos where the wild-type dynamics of these proteins are maintained. Taken together these results suggest that spindle matrix formation may be a general requirement for the localization and proper dynamics of cell cycle factors promoting signaling events leading to cell cycle progression.
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Affiliation(s)
- Changfu Yao
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
| | - Chao Wang
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
| | - Yeran Li
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
| | - Michael Zavortink
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
| | | | - Jack Girton
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
| | - Kristen M Johansen
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
| | - Jørgen Johansen
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
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Jiang H, Wang S, Huang Y, He X, Cui H, Zhu X, Zheng Y. Phase transition of spindle-associated protein regulate spindle apparatus assembly. Cell 2015; 163:108-22. [PMID: 26388440 DOI: 10.1016/j.cell.2015.08.010] [Citation(s) in RCA: 206] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 06/09/2015] [Accepted: 07/31/2015] [Indexed: 11/24/2022]
Abstract
Spindle assembly required during mitosis depends on microtubule polymerization. We demonstrate that the evolutionarily conserved low-complexity protein, BuGZ, undergoes phase transition or coacervation to promote assembly of both spindles and their associated components. BuGZ forms temperature-dependent liquid droplets alone or on microtubules in physiological buffers. Coacervation in vitro or in spindle and spindle matrix depends on hydrophobic residues in BuGZ. BuGZ coacervation and its binding to microtubules and tubulin are required to promote assembly of spindle and spindle matrix in Xenopus egg extract and in mammalian cells. Since several previously identified spindle-associated components also contain low-complexity regions, we propose that coacervating proteins may be a hallmark of proteins that comprise a spindle matrix that functions to promote assembly of spindles by concentrating its building blocks.
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Affiliation(s)
- Hao Jiang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China; Department of Embryology, Carnegie Institution for Science, 3520 San Martin Drive, Baltimore, MD 21218, USA
| | - Shusheng Wang
- Department of Embryology, Carnegie Institution for Science, 3520 San Martin Drive, Baltimore, MD 21218, USA
| | - Yuejia Huang
- Department of Embryology, Carnegie Institution for Science, 3520 San Martin Drive, Baltimore, MD 21218, USA
| | - Xiaonan He
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Honggang Cui
- Department of Chemical and Biomolecular Engineering and Institute for NanoBioTechnology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Xueliang Zhu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China.
| | - Yixian Zheng
- Department of Embryology, Carnegie Institution for Science, 3520 San Martin Drive, Baltimore, MD 21218, USA.
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Forer A, Johansen KM, Johansen J. Movement of chromosomes with severed kinetochore microtubules. PROTOPLASMA 2015; 252:775-781. [PMID: 25576435 DOI: 10.1007/s00709-014-0752-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 12/17/2014] [Indexed: 06/04/2023]
Abstract
Experiments dating from 1966 and thereafter showed that anaphase chromosomes continued to move poleward after their kinetochore microtubules were severed by ultraviolet microbeam irradiation. These observations were initially met with scepticism as they contradicted the prevailing view that kinetochore fibre microtubules pulled chromosomes to the pole. However, recent experiments using visible light laser microbeam irradiations have corroborated these earlier experiments as anaphase chromosomes again were shown to move poleward after their kinetochore microtubules were severed. Thus, multiple independent studies using different techniques have shown that chromosomes can indeed move poleward without direct microtubule connections to the pole, with only a kinetochore 'stub' of microtubules. An issue not yet settled is: what propels the disconnected chromosome? There are two not necessarily mutually exclusive proposals in the literature: (1) chromosome movement is propelled by the kinetochore stub interacting with non-kinetochore microtubules and (2) chromosome movement is propelled by a spindle matrix acting on the stub. In this review, we summarise the data indicating that chromosomes can move with severed kinetochore microtubules and we discuss proposed mechanisms for chromosome movement with severed kinetochore microtubules.
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Affiliation(s)
- Arthur Forer
- Biology Department, York University, North York, Ontario, M3J 1P3, Canada,
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