1
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Bouchez D, Uyttewaal M, Pastuglia M. Spatiotemporal regulation of plant cell division. CURRENT OPINION IN PLANT BIOLOGY 2024; 79:102530. [PMID: 38631088 DOI: 10.1016/j.pbi.2024.102530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 03/13/2024] [Accepted: 03/21/2024] [Indexed: 04/19/2024]
Abstract
Plant morphogenesis largely depends on the orientation and rate of cell division and elongation, and their coordination at all levels of organization. Despite recent progresses in the comprehension of pathways controlling division plane determination in plant cells, many pieces are missing to the puzzle. For example, we have a partial comprehension of formation, function and evolutionary significance of the preprophase band, a plant-specific cytoskeletal array involved in premitotic setup of the division plane, as well as the role of the nucleus and its connection to the preprophase band of microtubules. Likewise, several modeling studies point to a strong relationship between cell shape and division geometry, but the emergence of such geometric rules from the molecular and cellular pathways at play are still obscure. Yet, recent imaging technologies and genetic tools hold a lot of promise to tackle these challenges and to revisit old questions with unprecedented resolution in space and time.
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Affiliation(s)
- David Bouchez
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), Versailles 78000, France.
| | - Magalie Uyttewaal
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), Versailles 78000, France
| | - Martine Pastuglia
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), Versailles 78000, France
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2
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Wang Y, Liu YR, Wang PY, Xie P. Computational Studies Reveal How Passive Cross-Linkers Regulate Anaphase Spindle Elongation. J Phys Chem B 2024; 128:1194-1204. [PMID: 38287918 DOI: 10.1021/acs.jpcb.3c07655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2024]
Abstract
In eukaryotic cell division, a series of events are organized to produce two daughter cells. The spindle elongation in anaphase B is essential for providing enough space to maintain cell size and distribute sister chromatids properly, which is associated with microtubules and microtubule-associated proteins such as kinesin-5 Eg5 and the Ase1-related protein, PRC1. The available experimental data indicated that after the start of anaphase B more PRC1 proteins can bind to the antiparallel microtubule pairs in the spindle but the excess amount of PRC1 proteins can lead to the failure of cell division, indicating that PRC1 proteins can regulate the spindle elongation in a concentration-dependent manner. However, the underlying mechanism of the PRC1 proteins regulating the spindle elongation has not been explained up to now. Here, we use a simplified model, where only the two important participants (kinesin-5 Eg5 motors and PRC1 proteins) are considered, to study the spindle elongation during anaphase B. We first show that only in the appropriate range of the PRC1 concentration can the spindle elongation complete properly. Furthermore, we explore the underlying mechanism of PRC1 as a regulator for spindle elongation.
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Affiliation(s)
- Yao Wang
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yu-Ru Liu
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peng-Ye Wang
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ping Xie
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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3
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Sasaki T, Saito K, Inoue D, Serk H, Sugiyama Y, Pesquet E, Shimamoto Y, Oda Y. Confined-microtubule assembly shapes three-dimensional cell wall structures in xylem vessels. Nat Commun 2023; 14:6987. [PMID: 37957173 PMCID: PMC10643555 DOI: 10.1038/s41467-023-42487-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 10/12/2023] [Indexed: 11/15/2023] Open
Abstract
Properly patterned deposition of cell wall polymers is prerequisite for the morphogenesis of plant cells. A cortical microtubule array guides the two-dimensional pattern of cell wall deposition. Yet, the mechanism underlying the three-dimensional patterning of cell wall deposition is poorly understood. In metaxylem vessels, cell wall arches are formed over numerous pit membranes, forming highly organized three-dimensional cell wall structures. Here, we show that the microtubule-associated proteins, MAP70-5 and MAP70-1, regulate arch development. The map70-1 map70-5 plants formed oblique arches in an abnormal orientation in pits. Microtubules fit the aperture of developing arches in wild-type cells, whereas microtubules in map70-1 map70-5 cells extended over the boundaries of pit arches. MAP70 caused the bending and bundling of microtubules. These results suggest that MAP70 confines microtubules within the pit apertures by altering the physical properties of microtubules, thereby directing the growth of pit arches in the proper orientation. This study provides clues to understanding how plants develop three-dimensional structure of cell walls.
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Affiliation(s)
- Takema Sasaki
- Department of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Kei Saito
- Department of Chromosome Science, National Institute of Genetics, Mishima, Shizuoka, Japan
- Department of Genetics, SOKENDAI University, Mishima, Shizuoka, Japan
| | - Daisuke Inoue
- Factuly of Design, Kyusyu University, Fukuoka, Japan
| | - Henrik Serk
- Umeå Plant Science Centre (UPSC), Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Yuki Sugiyama
- Department of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
- Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Edouard Pesquet
- Umeå Plant Science Centre (UPSC), Department of Plant Physiology, Umeå University, Umeå, Sweden
- Arrhenius laboratories, Department of Ecology, Environment and Plant Sciences (DEEP), Stockholm University, Stockholm, Sweden
| | - Yuta Shimamoto
- Department of Chromosome Science, National Institute of Genetics, Mishima, Shizuoka, Japan
- Department of Genetics, SOKENDAI University, Mishima, Shizuoka, Japan
| | - Yoshihisa Oda
- Department of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan.
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4
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Valdez VA, Neahring L, Petry S, Dumont S. Mechanisms underlying spindle assembly and robustness. Nat Rev Mol Cell Biol 2023; 24:523-542. [PMID: 36977834 PMCID: PMC10642710 DOI: 10.1038/s41580-023-00584-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2023] [Indexed: 03/30/2023]
Abstract
The microtubule-based spindle orchestrates chromosome segregation during cell division. Following more than a century of study, many components and pathways contributing to spindle assembly have been described, but how the spindle robustly assembles remains incompletely understood. This process involves the self-organization of a large number of molecular parts - up to hundreds of thousands in vertebrate cells - whose local interactions give rise to a cellular-scale structure with emergent architecture, mechanics and function. In this Review, we discuss key concepts in our understanding of spindle assembly, focusing on recent advances and the new approaches that enabled them. We describe the pathways that generate the microtubule framework of the spindle by driving microtubule nucleation in a spatially controlled fashion and present recent insights regarding the organization of individual microtubules into structural modules. Finally, we discuss the emergent properties of the spindle that enable robust chromosome segregation.
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Affiliation(s)
| | - Lila Neahring
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA, USA
- Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA, USA
| | - Sabine Petry
- Molecular Biology, Princeton University, Princeton, NJ, USA.
| | - Sophie Dumont
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA, USA.
- Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA, USA.
- Department of Biochemistry & Biophysics, UCSF, San Francisco, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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5
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Yu WX, Li YK, Xu MF, Xu CJ, Chen J, Wei YL, She ZY. Kinesin-5 Eg5 is essential for spindle assembly, chromosome stability and organogenesis in development. Cell Death Dis 2022; 8:490. [PMID: 36513626 DOI: 10.1038/s41420-022-01281-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 12/06/2022] [Accepted: 12/07/2022] [Indexed: 12/15/2022]
Abstract
Chromosome stability relies on bipolar spindle assembly and faithful chromosome segregation during cell division. Kinesin-5 Eg5 is a plus-end-directed kinesin motor protein, which is essential for spindle pole separation and chromosome alignment in mitosis. Heterozygous Eg5 mutations cause autosomal-dominant microcephaly, primary lymphedema, and chorioretinal dysplasia syndrome in humans. However, the developmental roles and cellular mechanisms of Eg5 in organogenesis remain largely unknown. In this study, we have shown that Eg5 inhibition leads to the formation of the monopolar spindle, chromosome misalignment, polyploidy, and subsequent apoptosis. Strikingly, long-term inhibition of Eg5 stimulates the immune responses and the accumulation of lymphocytes in the mouse spleen through the innate and specific immunity pathways. Eg5 inhibition results in metaphase arrest and cell growth inhibition, and suppresses the formation of somite and retinal development in zebrafish embryos. Our data have revealed the essential roles of kinesin-5 Eg5 involved in cell proliferation, chromosome stability, and organogenesis during development. Our findings shed a light on the cellular basis and pathogenesis in microcephaly, primary lymphedema, and chorioretinal dysplasia syndrome of Eg5-mutation-positive patients.
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Affiliation(s)
- Wen-Xin Yu
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, 350122, Fuzhou, Fujian, China.,Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, 350122, Fuzhou, Fujian, China
| | - Yu-Kun Li
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, 350122, Fuzhou, Fujian, China.,Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, 350122, Fuzhou, Fujian, China
| | - Meng-Fei Xu
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, 350122, Fuzhou, Fujian, China.,Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, 350122, Fuzhou, Fujian, China
| | - Chen-Jie Xu
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, 350122, Fuzhou, Fujian, China.,Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, 350122, Fuzhou, Fujian, China
| | - Jie Chen
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, 350122, Fuzhou, Fujian, China.,Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, 350122, Fuzhou, Fujian, China
| | - Ya-Lan Wei
- Medical Research Center, Fujian Maternity and Child Health Hospital, 350001, Fuzhou, Fujian, China.,College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, 350122, Fuzhou, Fujian, China
| | - Zhen-Yu She
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, 350122, Fuzhou, Fujian, China. .,Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, 350122, Fuzhou, Fujian, China.
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6
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Suresh P, Galstyan V, Phillips R, Dumont S. Modeling and mechanical perturbations reveal how spatially regulated anchorage gives rise to spatially distinct mechanics across the mammalian spindle. eLife 2022; 11:e79558. [PMID: 36346735 PMCID: PMC9642996 DOI: 10.7554/elife.79558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 10/12/2022] [Indexed: 11/09/2022] Open
Abstract
During cell division, the spindle generates force to move chromosomes. In mammals, microtubule bundles called kinetochore-fibers (k-fibers) attach to and segregate chromosomes. To do so, k-fibers must be robustly anchored to the dynamic spindle. We previously developed microneedle manipulation to mechanically challenge k-fiber anchorage, and observed spatially distinct response features revealing the presence of heterogeneous anchorage (Suresh et al., 2020). How anchorage is precisely spatially regulated, and what forces are necessary and sufficient to recapitulate the k-fiber's response to force remain unclear. Here, we develop a coarse-grained k-fiber model and combine with manipulation experiments to infer underlying anchorage using shape analysis. By systematically testing different anchorage schemes, we find that forces solely at k-fiber ends are sufficient to recapitulate unmanipulated k-fiber shapes, but not manipulated ones for which lateral anchorage over a 3 μm length scale near chromosomes is also essential. Such anchorage robustly preserves k-fiber orientation near chromosomes while allowing pivoting around poles. Anchorage over a shorter length scale cannot robustly restrict pivoting near chromosomes, while anchorage throughout the spindle obstructs pivoting at poles. Together, this work reveals how spatially regulated anchorage gives rise to spatially distinct mechanics in the mammalian spindle, which we propose are key for function.
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Affiliation(s)
- Pooja Suresh
- Biophysics Graduate Program, University of California, San FranciscoSan FranciscoUnited States
- Department of Bioengineering and Therapeutic Sciences, University of California, San FranciscoSan FranciscoUnited States
| | - Vahe Galstyan
- Biochemistry and Molecular Biophysics Option, California Institute of TechnologyPasadenaUnited States
- A. Alikhanyan National Laboratory (Yerevan Physics Institute)YerevanArmenia
| | - Rob Phillips
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
- Department of Physics, California Institute of TechnologyPasadenaUnited States
- Chan Zuckerberg Biohub, San FranciscoSan FranciscoUnited States
| | - Sophie Dumont
- Biophysics Graduate Program, University of California, San FranciscoSan FranciscoUnited States
- Department of Bioengineering and Therapeutic Sciences, University of California, San FranciscoSan FranciscoUnited States
- Chan Zuckerberg Biohub, San FranciscoSan FranciscoUnited States
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
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7
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Morphological growth dynamics, mechanical stability, and active microtubule mechanics underlying spindle self-organization. Proc Natl Acad Sci U S A 2022; 119:e2209053119. [PMID: 36282919 PMCID: PMC9636915 DOI: 10.1073/pnas.2209053119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The spindle is a dynamic intracellular structure self-organized from microtubules and microtubule-associated proteins. The spindle’s bipolar morphology is essential for the faithful segregation of chromosomes during cell division, and it is robustly maintained by multifaceted mechanisms. However, abnormally shaped spindles, such as multipolar spindles, can stochastically arise in a cell population and cause chromosome segregation errors. The physical basis of how microtubules fail in bipolarization and occasionally favor nonbipolar assembly is poorly understood. Here, using live fluorescence imaging and quantitative shape analysis in
Xenopus
egg extracts, we find that spindles of varied shape morphologies emerge through nonrandom, bistable self-organization paths, one leading to a bipolar and the other leading to a multipolar phenotype. The bistability defines the spindle’s unique morphological growth dynamics linked to each shape phenotype and can be promoted by a locally distorted microtubule flow that arises within premature structures. We also find that bipolar and multipolar spindles are stable at the steady-state in bulk but can infrequently switch between the two phenotypes. Our microneedle-based physical manipulation further demonstrates that a transient force perturbation applied near the assembled pole can trigger the phenotypic switching, revealing the mechanical plasticity of the spindle. Together with molecular perturbation of kinesin-5 and augmin, our data propose the physical and molecular bases underlying the emergence of spindle-shape variation, which influences chromosome segregation fidelity during cell division.
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8
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Coupling of microtubule bundles isolates them from local disruptions to set the structural stability of the anaphase spindle. Proc Natl Acad Sci U S A 2022; 119:e2204068119. [PMID: 36122237 PMCID: PMC9522340 DOI: 10.1073/pnas.2204068119] [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: 11/18/2022] Open
Abstract
Chromosome segregation requires load-bearing interactions across kinetochore fibers and antiparallel microtubule bundles, which constitute the spindle midzone. Mechanical properties of kinetochore fibers have been characterized during metaphase, when the mitotic spindle achieves steady state. However, it has been difficult to probe the mechanics of the spindle midzone that elongates during anaphase. Here, we combine superresolution expansion and electron microscopies, lattice light-sheet imaging, and laser microsurgery to examine how midzone organization sets its mechanics. We find that individual midzone bundles extend out to multiple positions across chromosomes and form multiple apparent microtubule-based connections with each other. Across the spindle's short axis, these microtubule bundles exhibit restricted, submicrometer-amplitude motions, which are weakly correlated on <10s timescales. Severing individual midzone bundles near their center does not substantially affect positions of neighboring bundles, nor the overall structural stability of the midzone. In contrast, severing multiple midzone bundles or individual bundles at their chromosome-proximal ends significantly displaces neighboring microtubule bundles. Together, these data suggest a model wherein multiple midzone connections both reinforce its structure and mechanically isolate individual bundles from local perturbations. This feature sets the robust midzone architecture to accommodate disruptions, including those which result from lagging chromosomes, and achieve stereotypic outputs, such as proper chromosome separation.
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9
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She ZY, Zhong N, Wei YL. Kinesin-5 Eg5 mediates centrosome separation to control spindle assembly in spermatocytes. Chromosoma 2022; 131:87-105. [PMID: 35437661 DOI: 10.1007/s00412-022-00772-5] [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: 12/02/2021] [Revised: 03/12/2022] [Accepted: 04/08/2022] [Indexed: 11/25/2022]
Abstract
Timely and accurate centrosome separation is critical for bipolar spindle organization and faithful chromosome segregation during cell division. Kinesin-5 Eg5 is essential for centrosome separation and spindle organization in somatic cells; however, the detailed functions and mechanisms of Eg5 in spermatocytes remain unclear. In this study, we show that Eg5 proteins are located at spindle microtubules and centrosomes in spermatocytes both in vivo and in vitro. We reveal that the spermatocytes are arrested at metaphase I in seminiferous tubules after Eg5 inhibition. Eg5 ablation results in cell cycle arrest, the formation of monopolar spindle, and chromosome misalignment in cultured GC-2 spd cells. Importantly, we find that the long-term inhibition of Eg5 results in an increased number of centrosomes and chromosomal instability in spermatocytes. Our findings indicate that Eg5 mediates centrosome separation to control spindle assembly and chromosome alignment in spermatocytes, which finally contribute to chromosome stability and faithful cell division of the spermatocytes.
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Affiliation(s)
- Zhen-Yu She
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122, Fujian, China.
- Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, Fuzhou, 350122, Fujian, China.
| | - Ning Zhong
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122, Fujian, China
- Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, Fuzhou, 350122, Fujian, China
| | - Ya-Lan Wei
- Fujian Obstetrics and Gynecology Hospital, Fuzhou, 350011, Fujian, China
- Medical Research Center, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001, Fujian, China
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10
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Neahring L, Cho NH, Dumont S. Opposing motors provide mechanical and functional robustness in the human spindle. Dev Cell 2021; 56:3006-3018.e5. [PMID: 34614397 DOI: 10.1016/j.devcel.2021.09.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 07/27/2021] [Accepted: 09/13/2021] [Indexed: 11/30/2022]
Abstract
At each cell division, the spindle self-organizes from microtubules and motors. In human spindles, the motors dynein and Eg5 generate contractile and extensile stress, respectively. Inhibiting dynein or its targeting factor NuMA leads to unfocused, turbulent spindles, and inhibiting Eg5 leads to monopoles; yet, bipolar spindles form when both are inhibited together. What, then, are the roles of these opposing motors? Here, we generate NuMA/dynein- and Eg5-doubly inhibited spindles that not only attain a typical metaphase shape and size but also undergo anaphase. However, these spindles have reduced microtubule dynamics and are mechanically fragile, fracturing under force. Furthermore, they exhibit lagging chromosomes and a dramatic left-handed twist at anaphase. Thus, although these opposing motors are not required for spindle shape, they are essential to its mechanical and functional robustness. This work suggests a design principle whereby opposing active stresses provide robustness to force-generating cellular structures.
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Affiliation(s)
- Lila Neahring
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA 94158, USA; Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA 94143, USA.
| | - Nathan H Cho
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA 94158, USA; Tetrad Graduate Program, UCSF, San Francisco, CA 94158, USA
| | - Sophie Dumont
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA 94158, USA; Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA 94143, USA; Tetrad Graduate Program, UCSF, San Francisco, CA 94158, USA; Department of Biochemistry & Biophysics, UCSF, San Francisco, CA 94158, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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11
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Biswas A, Kim K, Cojoc G, Guck J, Reber S. The Xenopus spindle is as dense as the surrounding cytoplasm. Dev Cell 2021; 56:967-975.e5. [PMID: 33823135 DOI: 10.1016/j.devcel.2021.03.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/11/2021] [Accepted: 03/08/2021] [Indexed: 12/22/2022]
Abstract
The mitotic spindle is a self-organizing molecular machine, where hundreds of different molecules continuously interact to maintain a dynamic steady state. While our understanding of key molecular players in spindle assembly is significant, it is still largely unknown how the spindle's material properties emerge from molecular interactions. Here, we use correlative fluorescence imaging and label-free three-dimensional optical diffraction tomography (ODT) to measure the Xenopus spindle's mass density distribution. While the spindle has been commonly referred to as a denser phase of the cytoplasm, we find that it has the same density as its surrounding, which makes it neutrally buoyant. Molecular perturbations suggest that spindle mass density can be modulated by tuning microtubule nucleation and dynamics. Together, ODT provides direct, unbiased, and quantitative information of the spindle's emergent physical properties-essential to advance predictive frameworks of spindle assembly and function.
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Affiliation(s)
- Abin Biswas
- IRI Life Sciences, Humboldt-Universität zu Berlin, 10115 Berlin, Germany; Max-Planck-Institute for the Science of Light, 91058 Erlangen, Germany
| | - Kyoohyun Kim
- Max-Planck-Institute for the Science of Light, 91058 Erlangen, Germany; BIOTEC, Technische Universität Dresden, 01307 Dresden, Germany
| | - Gheorghe Cojoc
- BIOTEC, Technische Universität Dresden, 01307 Dresden, Germany
| | - Jochen Guck
- Max-Planck-Institute for the Science of Light, 91058 Erlangen, Germany; BIOTEC, Technische Universität Dresden, 01307 Dresden, Germany; Cluster of Excellence Physics of Life, Technische Universität Dresden, 01307 Dresden, Germany
| | - Simone Reber
- IRI Life Sciences, Humboldt-Universität zu Berlin, 10115 Berlin, Germany; University of Applied Sciences Berlin, 13353 Berlin, Germany.
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12
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Mechanical Mechanisms of Chromosome Segregation. Cells 2021; 10:cells10020465. [PMID: 33671543 PMCID: PMC7926803 DOI: 10.3390/cells10020465] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/17/2021] [Accepted: 02/19/2021] [Indexed: 12/11/2022] Open
Abstract
Chromosome segregation—the partitioning of genetic material into two daughter cells—is one of the most crucial processes in cell division. In all Eukaryotes, chromosome segregation is driven by the spindle, a microtubule-based, self-organizing subcellular structure. Extensive research performed over the past 150 years has identified numerous commonalities and contrasts between spindles in different systems. In this review, we use simple coarse-grained models to organize and integrate previous studies of chromosome segregation. We discuss sites of force generation in spindles and fundamental mechanical principles that any understanding of chromosome segregation must be based upon. We argue that conserved sites of force generation may interact differently in different spindles, leading to distinct mechanical mechanisms of chromosome segregation. We suggest experiments to determine which mechanical mechanism is operative in a particular spindle under study. Finally, we propose that combining biophysical experiments, coarse-grained theories, and evolutionary genetics will be a productive approach to enhance our understanding of chromosome segregation in the future.
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13
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Wang W, Shao S, Chen W, Wang W, Chuai Y, Li Y, Guo Y, Han S, Shu M, Wang Q, Zhang L, Shang W. Electrofusion Stimulation Is an Independent Factor of Chromosome Abnormality in Mice Oocytes Reconstructed via Spindle Transfer. Front Endocrinol (Lausanne) 2021; 12:705837. [PMID: 34413830 PMCID: PMC8370092 DOI: 10.3389/fendo.2021.705837] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 07/06/2021] [Indexed: 11/28/2022] Open
Abstract
Oocytes reconstructed by spindle transfer (ST) are prone to chromosome abnormality, which is speculated to be caused by mechanical interference or premature activation, the mechanism is controversial. In this study, C57BL/6N oocytes were used as the model, and electrofusion ST was performed under normal conditions, Ca2+ free, and at room temperature, respectively. The effect of enucleation and electrofusion stimulation on MPF activity, spindle morphology, γ-tubulin localization and chromosome arrangement was compared. We found that electrofusion stimulation could induce premature chromosome separation and abnormal spindle morphology and assembly by decreasing the MPF activity, leading to premature activation, and thus resulting in chromosome abnormality in oocytes reconstructed via ST. Electrofusion stimulation was an independent factor of chromosome abnormality in oocytes reconstructed via ST, and was not related to enucleation, fusion status, temperature, or Ca2+. The electrofusion stimulation number should be minimized, with no more than 2 times being appropriate. As the electrofusion stimulation number increased, several typical abnormalities in chromosome arrangement and spindle assembly occurred. Although blastocyst culture could eliminate embryos with chromosomal abnormalities, it would significantly decrease the number of normal embryos and reduce the availability of embryos. The optimum operating condition for electrofusion ST was the 37°C group without Ca2+.
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Affiliation(s)
- Wei Wang
- Department of Histology and Embryology, Hebei Medical University, Shijiazhuang, China
- Department of Obstetrics and Gynecology, The Sixth Medical Center of Chinese People’s Liberation Army (PLA) General Hospital, Beijing, China
- Department of Obstetrics and Gynecology, Chinese PLA General Hospital, Beijing, China
- Department of Reproductive Medicine, Harrison International Peace Hospital, Hengshui, China
| | - Suxia Shao
- Department of Histology and Embryology, Hebei Medical University, Shijiazhuang, China
| | - Wei Chen
- Department of Histology and Embryology, Hebei Medical University, Shijiazhuang, China
| | - Weizhou Wang
- Department of Obstetrics and Gynecology, The Sixth Medical Center of Chinese People’s Liberation Army (PLA) General Hospital, Beijing, China
- Department of Obstetrics and Gynecology, Chinese PLA General Hospital, Beijing, China
| | - Yunhai Chuai
- Department of Obstetrics and Gynecology, The Sixth Medical Center of Chinese People’s Liberation Army (PLA) General Hospital, Beijing, China
- Department of Obstetrics and Gynecology, Chinese PLA General Hospital, Beijing, China
| | - Yunfei Li
- Department of Histology and Embryology, Hebei Medical University, Shijiazhuang, China
- Department of Obstetrics and Gynecology, The Sixth Medical Center of Chinese People’s Liberation Army (PLA) General Hospital, Beijing, China
- Department of Obstetrics and Gynecology, Chinese PLA General Hospital, Beijing, China
| | - Yiming Guo
- Department of Biology, Kenneth P. Dietrich School of Art & Science, University of Pittsburgh, Pittsburgh, PA, United States
| | - Shujie Han
- Department of Obstetrics and Gynecology, The Sixth Medical Center of Chinese People’s Liberation Army (PLA) General Hospital, Beijing, China
- Department of Obstetrics and Gynecology, Chinese PLA General Hospital, Beijing, China
- Navy Clinical Medical School, Anhui Medical University, Beijing, China
| | - Mingming Shu
- Department of Obstetrics and Gynecology, The Sixth Medical Center of Chinese People’s Liberation Army (PLA) General Hospital, Beijing, China
- Department of Obstetrics and Gynecology, Chinese PLA General Hospital, Beijing, China
| | - Qihang Wang
- Department of Reproductive Medicine, First Hospital of Tsinghua University, Beijing, China
| | - Lei Zhang
- Department of Histology and Embryology, Hebei Medical University, Shijiazhuang, China
- *Correspondence: Lei Zhang, ; Wei Shang,
| | - Wei Shang
- Department of Obstetrics and Gynecology, The Sixth Medical Center of Chinese People’s Liberation Army (PLA) General Hospital, Beijing, China
- Department of Obstetrics and Gynecology, Chinese PLA General Hospital, Beijing, China
- Navy Clinical Medical School, Anhui Medical University, Beijing, China
- *Correspondence: Lei Zhang, ; Wei Shang,
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14
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Pavin N, Tolić IM. Mechanobiology of the Mitotic Spindle. Dev Cell 2020; 56:192-201. [PMID: 33238148 DOI: 10.1016/j.devcel.2020.11.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/06/2020] [Accepted: 11/02/2020] [Indexed: 10/22/2022]
Abstract
The mitotic spindle is a microtubule-based assembly that separates the chromosomes during cell division. As the spindle is basically a mechanical micro machine, the understanding of its functioning is constantly motivating the development of experimental approaches based on mechanical perturbations, which are complementary to and work together with the classical genetics and biochemistry methods. Recent data emerging from these approaches in combination with theoretical modeling led to novel ideas and significant revisions of the basic concepts in the field. In this Perspective, we discuss the advances in the understanding of spindle mechanics, focusing on microtubule forces that control chromosome movements.
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Affiliation(s)
- Nenad Pavin
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia.
| | - Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
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15
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Ong JY, Torres JZ. Phase Separation in Cell Division. Mol Cell 2020; 80:9-20. [PMID: 32860741 DOI: 10.1016/j.molcel.2020.08.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 07/10/2020] [Accepted: 08/07/2020] [Indexed: 02/08/2023]
Abstract
Cell division requires the assembly and organization of a microtubule spindle for the proper separation of chromosomes in mitosis and meiosis. Phase separation is an emerging paradigm for understanding spatial and temporal regulation of a variety of cellular processes, including cell division. Phase-separated condensates have been recently discovered at many structures during cell division as a possible mechanism for properly localizing, organizing, and activating proteins involved in cell division. Here, we review how these condensates play roles in regulating microtubule density and organization and spindle assembly and function and in activating some of the key players in cell division. We conclude with perspectives on areas of future research for this exciting and rapidly advancing field.
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Affiliation(s)
- Joseph Y Ong
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Jorge Z Torres
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA; Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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16
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Guilloux G, Gibeaux R. Mechanisms of spindle assembly and size control. Biol Cell 2020; 112:369-382. [PMID: 32762076 DOI: 10.1111/boc.202000065] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/03/2020] [Accepted: 08/03/2020] [Indexed: 01/09/2023]
Abstract
The spindle is crucial for cell division by allowing the faithful segregation of replicated chromosomes to daughter cells. Proper segregation is ensured only if microtubules (MTs) and hundreds of other associated factors interact to assemble this complex structure with the appropriate architecture and size. In this review, we describe the latest view of spindle organisation as well as the molecular gradients and mechanisms underlying MT nucleation and spindle assembly. We then discuss the overlapping physical and molecular constraints that dictate spindle morphology, concluding with a focus on spindle size regulation.
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Affiliation(s)
- Gabriel Guilloux
- Univ Rennes, CNRS, IGDR [(Institute of Genetics and Development of Rennes)] - UMR 6290, F-35000 Rennes, France
| | - Romain Gibeaux
- Univ Rennes, CNRS, IGDR [(Institute of Genetics and Development of Rennes)] - UMR 6290, F-35000 Rennes, France
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17
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Long AF, Suresh P, Dumont S. Individual kinetochore-fibers locally dissipate force to maintain robust mammalian spindle structure. J Cell Biol 2020; 219:e201911090. [PMID: 32435797 PMCID: PMC7401803 DOI: 10.1083/jcb.201911090] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 03/16/2020] [Accepted: 04/27/2020] [Indexed: 01/16/2023] Open
Abstract
At cell division, the mammalian kinetochore binds many spindle microtubules that make up the kinetochore-fiber. To segregate chromosomes, the kinetochore-fiber must be dynamic and generate and respond to force. Yet, how it remodels under force remains poorly understood. Kinetochore-fibers cannot be reconstituted in vitro, and exerting controlled forces in vivo remains challenging. Here, we use microneedles to pull on mammalian kinetochore-fibers and probe how sustained force regulates their dynamics and structure. We show that force lengthens kinetochore-fibers by persistently favoring plus-end polymerization, not by increasing polymerization rate. We demonstrate that force suppresses depolymerization at both plus and minus ends, rather than sliding microtubules within the kinetochore-fiber. Finally, we observe that kinetochore-fibers break but do not detach from kinetochores or poles. Together, this work suggests an engineering principle for spindle structural homeostasis: different physical mechanisms of local force dissipation by the k-fiber limit force transmission to preserve robust spindle structure. These findings may inform how other dynamic, force-generating cellular machines achieve mechanical robustness.
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Affiliation(s)
- Alexandra F. Long
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA
- Department of Bioengineering and Therapeutic Science, University of California, San Francisco, San Francisco, CA
| | - Pooja Suresh
- Biophysics Graduate Program, University of California, San Francisco, San Francisco, CA
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA
- Department of Bioengineering and Therapeutic Science, University of California, San Francisco, San Francisco, CA
| | - Sophie Dumont
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA
- Biophysics Graduate Program, University of California, San Francisco, San Francisco, CA
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA
- Department of Bioengineering and Therapeutic Science, University of California, San Francisco, San Francisco, CA
- Chan Zuckerberg Biohub, San Francisco, CA
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18
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Nazockdast E, Redemann S. Mechanics of the spindle apparatus. Semin Cell Dev Biol 2020; 107:91-102. [PMID: 32747191 DOI: 10.1016/j.semcdb.2020.06.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 06/02/2020] [Accepted: 06/30/2020] [Indexed: 12/01/2022]
Abstract
During mitosis microtubules self-organize to form a bipolar mitotic spindle structure, which positions the sister chromatids on the spindle mid-plane and separates them afterwards. Previous studies have identified many spindle associated proteins. Yet, we do not fully understand how these nanoscopic proteins lead to force generation through interactions of individual microtubules, motor proteins and chromosomes, and how a large number of these local interactions ultimately determine the structure and mechanics of the spindle in micron scale. Here we review the current understanding and open questions related to the structure and mechanics of the mitotic spindle. We then discuss how a combination of electron microscopy and computational modeling can be used to tackle some of these open questions.
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Affiliation(s)
- Ehssan Nazockdast
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3250, USA.
| | - Stefanie Redemann
- Center for Membrane and Cell Physiology & Department of Molecular Physiology and Biological Physics, University of Virginia, School of Medicine, Charlottesville, VA, USA.
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19
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Suresh P, Long AF, Dumont S. Microneedle manipulation of the mammalian spindle reveals specialized, short-lived reinforcement near chromosomes. eLife 2020; 9:e53807. [PMID: 32191206 PMCID: PMC7117910 DOI: 10.7554/elife.53807] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 03/18/2020] [Indexed: 12/21/2022] Open
Abstract
The spindle generates force to segregate chromosomes at cell division. In mammalian cells, kinetochore-fibers connect chromosomes to the spindle. The dynamic spindle anchors kinetochore-fibers in space and time to move chromosomes. Yet, how it does so remains poorly understood as we lack tools to directly challenge this anchorage. Here, we adapt microneedle manipulation to exert local forces on the spindle with spatiotemporal control. Pulling on kinetochore-fibers reveals the preservation of local architecture in the spindle-center over seconds. Sister, but not neighbor, kinetochore-fibers remain tightly coupled, restricting chromosome stretching. Further, pulled kinetochore-fibers pivot around poles but not chromosomes, retaining their orientation within 3 μm of chromosomes. This local reinforcement has a 20 s lifetime, and requires the microtubule crosslinker PRC1. Together, these observations indicate short-lived, specialized reinforcement in the spindle center. This could help protect chromosome attachments from transient forces while allowing spindle remodeling, and chromosome movements, over longer timescales.
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Affiliation(s)
- Pooja Suresh
- Biophysics Graduate Program, University of California, San FranciscoSan FranciscoUnited States
- Department of Cell and Tissue Biology, University of California, San FranciscoSan FranciscoUnited States
- Department of Bioengineering and Therapeutic Sciences, University of California, San FranciscoSan FranciscoUnited States
| | - Alexandra F Long
- Department of Cell and Tissue Biology, University of California, San FranciscoSan FranciscoUnited States
- Department of Bioengineering and Therapeutic Sciences, University of California, San FranciscoSan FranciscoUnited States
- Tetrad Graduate Program, University of California, San FranciscoSan FranciscoUnited States
| | - Sophie Dumont
- Biophysics Graduate Program, University of California, San FranciscoSan FranciscoUnited States
- Department of Cell and Tissue Biology, University of California, San FranciscoSan FranciscoUnited States
- Department of Bioengineering and Therapeutic Sciences, University of California, San FranciscoSan FranciscoUnited States
- Tetrad Graduate Program, University of California, San FranciscoSan FranciscoUnited States
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20
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Simunić J, Tolić IM. Meiotic Spindle Has a Soft Spot. Dev Cell 2019; 49:159-160. [PMID: 31014477 DOI: 10.1016/j.devcel.2019.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The spindle relies on forces exerted by microtubules and motor proteins to align and segregate chromosomes. In this issue of Developmental Cell, Takagi et al. (2019) show that meiotic spindle microtubules respond differently to forces at different spindle locations, depending on microtubule organization and motor proteins that crosslink them.
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Affiliation(s)
- Juraj Simunić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
| | - Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
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