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Le Cunff Y, Chesneau L, Pastezeur S, Pinson X, Soler N, Fairbrass D, Mercat B, Rodriguez-Garcia R, Alayan Z, Abdouni A, de Neidhardt G, Costes V, Anjubault M, Bouvrais H, Héligon C, Pécréaux J. Unveiling inter-embryo variability in spindle length over time: Towards quantitative phenotype analysis. PLoS Comput Biol 2024; 20:e1012330. [PMID: 39236069 PMCID: PMC11376571 DOI: 10.1371/journal.pcbi.1012330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Accepted: 07/15/2024] [Indexed: 09/07/2024] Open
Abstract
How can inter-individual variability be quantified? Measuring many features per experiment raises the question of choosing them to recapitulate high-dimensional data. Tackling this challenge on spindle elongation phenotypes, we showed that only three typical elongation patterns describe spindle elongation in C. elegans one-cell embryo. These archetypes, automatically extracted from the experimental data using principal component analysis (PCA), accounted for more than 95% of inter-individual variability of more than 1600 experiments across more than 100 different conditions. The two first archetypes were related to spindle average length and anaphasic elongation rate. The third archetype, accounting for 6% of the variability, was novel and corresponded to a transient spindle shortening in late metaphase, reminiscent of kinetochore function-defect phenotypes. Importantly, these three archetypes were robust to the choice of the dataset and were found even considering only non-treated conditions. Thus, the inter-individual differences between genetically perturbed embryos have the same underlying nature as natural inter-individual differences between wild-type embryos, independently of the temperatures. We thus propose that beyond the apparent complexity of the spindle, only three independent mechanisms account for spindle elongation, weighted differently in the various conditions. Interestingly, the spindle-length archetypes covered both metaphase and anaphase, suggesting that spindle elongation in late metaphase is sufficient to predict the late anaphase length. We validated this idea using a machine-learning approach. Finally, given amounts of these three archetypes could represent a quantitative phenotype. To take advantage of this, we set out to predict interacting genes from a seed based on the PCA coefficients. We exemplified this firstly on the role of tpxl-1 whose homolog tpx2 is involved in spindle microtubule branching, secondly the mechanism regulating metaphase length, and thirdly the central spindle players which set the length at anaphase. We found novel interactors not in public databases but supported by recent experimental publications.
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Affiliation(s)
- Yann Le Cunff
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Laurent Chesneau
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Sylvain Pastezeur
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Xavier Pinson
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Nina Soler
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Danielle Fairbrass
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Benjamin Mercat
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Ruddi Rodriguez-Garcia
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Zahraa Alayan
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Ahmed Abdouni
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Gary de Neidhardt
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Valentin Costes
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Mélodie Anjubault
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Hélène Bouvrais
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Christophe Héligon
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Jacques Pécréaux
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
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2
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Thomas A, Meraldi P. Centrosome age breaks spindle size symmetry even in cells thought to divide symmetrically. J Cell Biol 2024; 223:e202311153. [PMID: 39012627 PMCID: PMC11252449 DOI: 10.1083/jcb.202311153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 03/14/2024] [Accepted: 05/03/2024] [Indexed: 07/17/2024] Open
Abstract
Centrosomes are the main microtubule-organizing centers in animal cells. Due to the semiconservative nature of centrosome duplication, the two centrosomes differ in age. In asymmetric stem cell divisions, centrosome age can induce an asymmetry in half-spindle lengths. However, whether centrosome age affects the symmetry of the two half-spindles in tissue culture cells thought to divide symmetrically is unknown. Here, we show that in human epithelial and fibroblastic cell lines centrosome age imposes a mild spindle asymmetry that leads to asymmetric cell daughter sizes. At the mechanistic level, we show that this asymmetry depends on a cenexin-bound pool of the mitotic kinase Plk1, which favors the preferential accumulation on old centrosomes of the microtubule nucleation-organizing proteins pericentrin, γ-tubulin, and Cdk5Rap2, and microtubule regulators TPX2 and ch-TOG. Consistently, we find that old centrosomes have a higher microtubule nucleation capacity. We postulate that centrosome age breaks spindle size symmetry via microtubule nucleation even in cells thought to divide symmetrically.
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Affiliation(s)
- Alexandre Thomas
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Patrick Meraldi
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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3
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Sun M, Wang Y, Xin G, Yang B, Jiang Q, Zhang C. NuSAP regulates microtubule flux and Kif2A localization to ensure accurate chromosome congression. J Cell Biol 2024; 223:e202108070. [PMID: 38117947 PMCID: PMC10733630 DOI: 10.1083/jcb.202108070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 10/10/2023] [Accepted: 11/26/2023] [Indexed: 12/22/2023] Open
Abstract
Precise chromosome congression and segregation requires the proper assembly of a steady-state metaphase spindle, which is dynamic and maintained by continuous microtubule flux. NuSAP is a microtubule-stabilizing and -bundling protein that promotes chromosome-dependent spindle assembly. However, its function in spindle dynamics remains unclear. Here, we demonstrate that NuSAP regulates the metaphase spindle length control. Mechanistically, NuSAP facilitates kinetochore capture and spindle assembly by promoting Eg5 binding to microtubules. It also prevents excessive microtubule depolymerization through interaction with Kif2A, which reduces Kif2A spindle-pole localization. NuSAP is phosphorylated by Aurora A at Ser-240 during mitosis, and this phosphorylation promotes its interaction with Kif2A on the spindle body and reduces its localization with the spindle poles, thus maintaining proper spindle microtubule flux. NuSAP knockout resulted in the formation of shorter spindles with faster microtubule flux and chromosome misalignment. Taken together, we uncover that NuSAP participates in spindle assembly, dynamics, and metaphase spindle length control through the regulation of microtubule flux and Kif2A localization.
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Affiliation(s)
- Mengjie Sun
- The Academy for Cell and Life Health, Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
- The Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Yao Wang
- The Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Guangwei Xin
- The Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Biying Yang
- The Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Qing Jiang
- The Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Chuanmao Zhang
- The Academy for Cell and Life Health, Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
- The Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
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4
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Kiyomitsu A, Nishimura T, Hwang SJ, Ansai S, Kanemaki MT, Tanaka M, Kiyomitsu T. Ran-GTP assembles a specialized spindle structure for accurate chromosome segregation in medaka early embryos. Nat Commun 2024; 15:981. [PMID: 38302485 PMCID: PMC10834446 DOI: 10.1038/s41467-024-45251-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 01/19/2024] [Indexed: 02/03/2024] Open
Abstract
Despite drastic cellular changes during cleavage, a mitotic spindle assembles in each blastomere to accurately segregate duplicated chromosomes. Mechanisms of mitotic spindle assembly have been extensively studied using small somatic cells. However, mechanisms of spindle assembly in large vertebrate embryos remain little understood. Here, we establish functional assay systems in medaka (Oryzias latipes) embryos by combining CRISPR knock-in with auxin-inducible degron technology. Live imaging reveals several unexpected features of microtubule organization and centrosome positioning that achieve rapid, accurate cleavage. Importantly, Ran-GTP assembles a dense microtubule network at the metaphase spindle center that is essential for chromosome segregation in early embryos. This unique spindle structure is remodeled into a typical short, somatic-like spindle after blastula stages, when Ran-GTP becomes dispensable for chromosome segregation. We propose that despite the presence of centrosomes, the chromosome-derived Ran-GTP pathway has essential roles in functional spindle assembly in large, rapidly dividing vertebrate early embryos, similar to acentrosomal spindle assembly in oocytes.
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Affiliation(s)
- Ai Kiyomitsu
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | - Toshiya Nishimura
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan
- Hokkaido University Fisheries Sciences, 3-1-1, Minato-cho, Hakodate, Hokkaido, 041-8611, Japan
| | - Shiang Jyi Hwang
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | - Satoshi Ansai
- Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, 980-8577, Japan
- Laboratory of Genome Editing Breeding, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Masato T Kanemaki
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), and Graduate Institute for Advanced Studies, SOKENDAI, Yata 1111, Mishima, Shizuoka, 411-8540, Japan
- Department of Biological Science, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Minoru Tanaka
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan
| | - Tomomi Kiyomitsu
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan.
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5
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Xie P. A model of microtubule depolymerization by kinesin-8 motor proteins. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2023; 141:87-122. [PMID: 38960488 DOI: 10.1016/bs.apcsb.2023.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
The dimeric kinesin-8 motors have the biological function of depolymerizing microtubules (MTs) from the plus end. However, the molecular mechanism of the depolymerization promoted by the kinesin-8 motors is still undetermined. Here, a model is proposed for the MT depolymerization by the kinesin-8 motors. Based on the model, the dynamics of depolymerization in the presence of the single motor at the MT plus end under no load and under load on the motor is studied theoretically. The dynamics of depolymerization in the presence of multiple motors at the MT plus end is also analyzed. The theoretical results explain well the available experimental data. The studies can also be applicable to other families of kinesin motors such as kinesin-13 mitotic centromere-associated kinesin motors that have the ability to depolymerize MTs.
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Affiliation(s)
- Ping Xie
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing, P.R. China.
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6
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Gergely ZR, Jones MH, Zhou B, Cash C, McIntosh JR, Betterton MD. Distinct regions of the kinesin-5 C-terminal tail are essential for mitotic spindle midzone localization and sliding force. Proc Natl Acad Sci U S A 2023; 120:e2306480120. [PMID: 37725645 PMCID: PMC10523502 DOI: 10.1073/pnas.2306480120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 07/05/2023] [Indexed: 09/21/2023] Open
Abstract
Kinesin-5 motor proteins play essential roles during mitosis in most organisms. Their tetrameric structure and plus-end-directed motility allow them to bind to and move along antiparallel microtubules, thereby pushing spindle poles apart to assemble a bipolar spindle. Recent work has shown that the C-terminal tail is particularly important to kinesin-5 function: The tail affects motor domain structure, ATP hydrolysis, motility, clustering, and sliding force measured for purified motors, as well as motility, clustering, and spindle assembly in cells. Because previous work has focused on presence or absence of the entire tail, the functionally important regions of the tail remain to be identified. We have therefore characterized a series of kinesin-5/Cut7 tail truncation alleles in fission yeast. Partial truncation causes mitotic defects and temperature-sensitive growth, while further truncation that removes the conserved BimC motif is lethal. We compared the sliding force generated by cut7 mutants using a kinesin-14 mutant background in which some microtubules detach from the spindle poles and are pushed into the nuclear envelope. These Cut7-driven protrusions decreased as more of the tail was truncated, and the most severe truncations produced no observable protrusions. Our observations suggest that the C-terminal tail of Cut7p contributes to both sliding force and midzone localization. In the context of sequential tail truncation, the BimC motif and adjacent C-terminal amino acids are particularly important for sliding force. In addition, moderate tail truncation increases midzone localization, but further truncation of residues N-terminal to the BimC motif decreases midzone localization.
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Affiliation(s)
- Zachary R Gergely
- Department of Physics, University of Colorado, Boulder, CO 80309
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309
| | - Michele H Jones
- Department of Physics, University of Colorado, Boulder, CO 80309
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309
| | - Bojun Zhou
- Department of Physics, University of Colorado, Boulder, CO 80309
| | - Cai Cash
- Department of Physics, University of Colorado, Boulder, CO 80309
| | - J Richard McIntosh
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309
| | - Meredith D Betterton
- Department of Physics, University of Colorado, Boulder, CO 80309
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309
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7
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Xie P. Molecular mechanism of interaction between kinesin motors affecting their residence times on microtubule lattice and end. J Theor Biol 2023; 571:111556. [PMID: 37301429 DOI: 10.1016/j.jtbi.2023.111556] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 03/05/2023] [Accepted: 06/04/2023] [Indexed: 06/12/2023]
Abstract
Kinesin superfamily can be classified into 14 subfamilies. Some families of kinesin motors such as kinesin-1 are responsible for long-distance intracellular transports and thus the motors are required to reside on the microtubule (MT) lattice for a longer time than at the end. Some families such as kinesin-8 Kip3 and kinesin-5 Eg5 are responsible for the regulation of MT length by depolymerizing or polymerizing the MT from the plus end and thus the motors are required to reside at the MT end for a long time. Under the crowded condition of the motors, it was found experimentally that the residence times of the kinesin-8 Kip3 and kinesin-5 Eg5 at the MT end are reduced greatly compared to the single-motor case. However, the underlying mechanism of different families of kinesin motors having different MT-end residence times is unknown. The molecular mechanism by which the interaction between the two motors greatly reduces the residence time of the motor at the MT end is elusive. In addition, during the processive stepping on the MT lattice, when two kinesin motors meet it is unknown how the interaction between them affects their dissociation rates. To address the above unclear issues, here we make a consistent and theoretical study of the residence times of the kinesin-1, kinesin-8 Kip3 and kinesin-5 Eg5 motors on the MT lattice and at the end under both the single-motor condition and multiple-motors or crowded condition.
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Affiliation(s)
- Ping Xie
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100190, China.
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8
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Gergely Z, Jones MH, Zhou B, Cash C, McIntosh R, Betterton M. Distinct regions of the kinesin-5 C-terminal tail are essential for mitotic spindle midzone localization and sliding force. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.01.538972. [PMID: 37205432 PMCID: PMC10187184 DOI: 10.1101/2023.05.01.538972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Kinesin-5 motor proteins play essential roles during mitosis in most organisms. Their tetrameric structure and plus-end-directed motility allow them to bind to and move along antiparallel microtubules, thereby pushing spindle poles apart to assemble a bipolar spindle. Recent work has shown that the C-terminal tail is particularly important to kinesin-5 function: the tail affects motor domain structure, ATP hydrolysis, motility, clustering, and sliding force measured for purified motors, as well as motility, clustering, and spindle assembly in cells. Because previous work has focused on presence or absence of the entire tail, the functionally important regions of the tail remain to be identified. We have therefore characterized a series of kinesin-5/Cut7 tail truncation alleles in fission yeast. Partial truncation causes mitotic defects and temperature-sensitive growth, while further truncation that removes the conserved BimC motif is lethal. We compared the sliding force generated by cut7 mutants using a kinesin-14 mutant background in which some microtubules detach from the spindle poles and are pushed into the nuclear envelope. These Cut7-driven protrusions decreased as more of the tail was truncated, and the most severe truncations produced no observable protrusions. Our observations suggest that the C-terminal tail of Cut7p contributes to both sliding force and midzone localization. In the context of sequential tail truncation, the BimC motif and adjacent C-terminal amino acids are particularly important for sliding force. In addition, moderate tail truncation increases midzone localization, but further truncation of residues N terminal to the BimC motif decreases midzone localization.
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9
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Sobajima T, Kowalczyk KM, Skylakakis S, Hayward D, Fulcher LJ, Neary C, Batley C, Kurlekar S, Roberts E, Gruneberg U, Barr FA. PP6 regulation of Aurora A-TPX2 limits NDC80 phosphorylation and mitotic spindle size. J Cell Biol 2023; 222:e202205117. [PMID: 36897279 PMCID: PMC10041653 DOI: 10.1083/jcb.202205117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 11/22/2022] [Accepted: 02/10/2023] [Indexed: 03/11/2023] Open
Abstract
Amplification of the mitotic kinase Aurora A or loss of its regulator protein phosphatase 6 (PP6) have emerged as drivers of genome instability. Cells lacking PPP6C, the catalytic subunit of PP6, have amplified Aurora A activity, and as we show here, enlarged mitotic spindles which fail to hold chromosomes tightly together in anaphase, causing defective nuclear structure. Using functional genomics to shed light on the processes underpinning these changes, we discover synthetic lethality between PPP6C and the kinetochore protein NDC80. We find that NDC80 is phosphorylated on multiple N-terminal sites during spindle formation by Aurora A-TPX2, exclusively at checkpoint-silenced, microtubule-attached kinetochores. NDC80 phosphorylation persists until spindle disassembly in telophase, is increased in PPP6C knockout cells, and is Aurora B-independent. An Aurora-phosphorylation-deficient NDC80-9A mutant reduces spindle size and suppresses defective nuclear structure in PPP6C knockout cells. In regulating NDC80 phosphorylation by Aurora A-TPX2, PP6 plays an important role in mitotic spindle formation and size control and thus the fidelity of cell division.
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Affiliation(s)
| | | | | | - Daniel Hayward
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, UK
| | - Luke J. Fulcher
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Colette Neary
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Caleb Batley
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Samvid Kurlekar
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Emile Roberts
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Ulrike Gruneberg
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Francis A. Barr
- Department of Biochemistry, University of Oxford, Oxford, UK
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10
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Gergely ZR, Ansari S, Jones MH, Zhou B, Cash C, McIntosh R, Betterton MD. The kinesin-5 protein Cut7 moves bidirectionally on fission yeast spindles with activity that increases in anaphase. J Cell Sci 2023; 136:jcs260474. [PMID: 36655493 PMCID: PMC10112985 DOI: 10.1242/jcs.260474] [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: 08/16/2022] [Accepted: 01/10/2023] [Indexed: 01/20/2023] Open
Abstract
Kinesin-5 motors are essential to separate mitotic spindle poles and assemble a bipolar spindle in many organisms. These motors crosslink and slide apart antiparallel microtubules via microtubule plus-end-directed motility. However, kinesin-5 localization is enhanced away from antiparallel overlaps. Increasing evidence suggests this localization occurs due to bidirectional motility or trafficking. The purified fission-yeast kinesin-5 protein Cut7 moves bidirectionally, but bidirectionality has not been shown in cells, and the function of the minus-end-directed movement is unknown. Here, we characterized the motility of Cut7 on bipolar and monopolar spindles and observed movement toward both plus- and minus-ends of microtubules. Notably, the activity of the motor increased at anaphase B onset. Perturbations to microtubule dynamics only modestly changed Cut7 movement, whereas Cut7 mutation reduced movement. These results suggest that the directed motility of Cut7 contributes to the movement of the motor. Comparison of the Cut7 mutant and human Eg5 (also known as KIF11) localization suggest a new hypothesis for the function of minus-end-directed motility and spindle-pole localization of kinesin-5s.
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Affiliation(s)
- Zachary R. Gergely
- Department of Physics, University of Colorado Boulder, Boulder, CO 80305, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80305, USA
| | - Saad Ansari
- Department of Physics, University of Colorado Boulder, Boulder, CO 80305, USA
| | - Michele H. Jones
- Department of Physics, University of Colorado Boulder, Boulder, CO 80305, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80305, USA
| | - Bojun Zhou
- Department of Physics, University of Colorado Boulder, Boulder, CO 80305, USA
| | - Cai Cash
- Department of Physics, University of Colorado Boulder, Boulder, CO 80305, USA
| | - Richard McIntosh
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80305, USA
| | - Meredith D. Betterton
- Department of Physics, University of Colorado Boulder, Boulder, CO 80305, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80305, USA
- Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
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11
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KYOGOKU H, KITAJIMA TS. The large cytoplasmic volume of oocyte. J Reprod Dev 2023; 69:1-9. [PMID: 36436912 PMCID: PMC9939283 DOI: 10.1262/jrd.2022-101] [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: 11/26/2022] Open
Abstract
The study of the size of cells and organelles has a long history, dating back to the 1600s when cells were defined. In particular, various methods have elucidated the size of the nucleus and the mitotic spindle in several species. However, little research has been conducted on oocyte size and organelles in mammals, and many questions remain to be answered. The appropriate size is essential to cell function properly. Oocytes have a very large cytoplasm, which is more than 100 times larger than that of general somatic cells in mammals. In this review, we discuss how oocytes acquire an enormous cytoplasmic size and the adverse effects of a large cytoplasmic size on cellular functions.
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Affiliation(s)
- Hirohisa KYOGOKU
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan,Laboratory for Chromosome Segregation, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Tomoya S KITAJIMA
- Laboratory for Chromosome Segregation, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
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12
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Xie P. A model for the catalytic activity of microtubule polymerases. Cytoskeleton (Hoboken) 2023; 80:7-20. [PMID: 36305831 DOI: 10.1002/cm.21734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 10/04/2022] [Accepted: 10/22/2022] [Indexed: 11/07/2022]
Abstract
A XMAP215/Stu2/Alp14 polymerase can catalyze processively the tubulin addition to the microtubule (MT) plus end. In this work, a model is proposed for the underlying molecular mechanism of the polymerase activity, where the polymerase can not only catalyze processively the tubulin addition to but also promote the tubulin removal from the MT plus end. Based on the model the dynamics of both the wild-type and mutant polymerases is studied theoretically, explaining consistently and well various available experimental data. To further test the model, predicted results are provided.
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Affiliation(s)
- Ping Xie
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing, China
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13
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Kletter T, Biswas A, Reber S. Engineering metaphase spindles: Construction site and building blocks. Curr Opin Cell Biol 2022; 79:102143. [PMID: 36436307 DOI: 10.1016/j.ceb.2022.102143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 09/08/2022] [Accepted: 10/21/2022] [Indexed: 11/27/2022]
Abstract
In an active, crowded cytoplasm, eukaryotic cells construct metaphase spindles from conserved building blocks to segregate chromosomes. Yet, spindles execute their function in a stunning variety of cell shapes and sizes across orders of magnitude. Thus, the current challenge is to understand how unique mesoscale spindle characteristics emerge from the interaction of molecular collectives. Key components of these collectives are tubulin dimers, which polymerise into microtubules. Despite all conservation, tubulin is a genetically and biochemically complex protein family, and we only begin to uncover how tubulin diversity affects microtubule dynamics and thus spindle assembly. Moreover, it is increasingly appreciated that spindles are dynamically intertwined with the cytoplasm that itself exhibits cell-type specific emergent properties with yet mostly unexplored consequences for spindle construction. Therefore, on our way toward a quantitative picture of spindle function, we need to understand molecular behaviour of the building blocks and connect it to the entire cellular context.
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Affiliation(s)
- Tobias Kletter
- IRI Life Sciences, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
| | - Abin Biswas
- IRI Life Sciences, Humboldt-Universität zu Berlin, 10115 Berlin, Germany; Max-Planck-Institute for the Science of Light, 91058 Erlangen, 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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14
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Allais A, FitzHarris G. Absence of a robust mitotic timer mechanism in early preimplantation mouse embryos leads to chromosome instability. Development 2022; 149:275859. [DOI: 10.1242/dev.200391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 05/12/2022] [Indexed: 01/07/2023]
Abstract
ABSTRACT
Preimplantation embryos often consist of a combination of euploid and aneuploid cells, suggesting that safeguards preventing the generation and propagation of aneuploid cells in somatic cells might be deficient in embryos. In somatic cells, a mitotic timer mechanism has been described, in which even a small increase in the duration of M phase can cause a cell cycle arrest in the subsequent interphase, preventing further propagation of cells that have undergone a potentially hazardously long M phase. Here, we report that cell divisions in the mouse embryo and embryonic development continue even after a mitotic prolongation of several hours. However, similar M-phase extensions caused cohesion fatigue, resulting in prematurely separated sister chromatids and the production of micronuclei. Only extreme prolongation of M phase caused a subsequent interphase arrest, through a mechanism involving DNA damage. Our data suggest that the simultaneous absence of a robust mitotic timer and susceptibility of the embryo to cohesion fatigue could contribute to chromosome instability in mammalian embryos.
This article has an associated ‘The people behind the papers’ interview.
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Affiliation(s)
- Adélaïde Allais
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM) 1 , H2X 0A9 Montréal, Québec , Canada
| | - Greg FitzHarris
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM) 1 , H2X 0A9 Montréal, Québec , Canada
- Université de Montréal 2 Department of OBGYN, and Department of Pathology and Cell Biology , , H3T 1C5 Montréal, Québec , Canada
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15
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Dema A, van Haren J, Wittmann T. Optogenetic EB1 inactivation shortens metaphase spindles by disrupting cortical force-producing interactions with astral microtubules. Curr Biol 2022; 32:1197-1205.e4. [PMID: 35090591 PMCID: PMC8930524 DOI: 10.1016/j.cub.2022.01.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 12/09/2021] [Accepted: 01/07/2022] [Indexed: 10/19/2022]
Abstract
Chromosome segregation is accomplished by the mitotic spindle, a bipolar micromachine built primarily from microtubules. Different microtubule populations contribute to spindle function: kinetochore microtubules attach and transmit forces to chromosomes, antiparallel interpolar microtubules support spindle structure, and astral microtubules connect spindle poles to the cell cortex.1,2 In mammalian cells, end-binding (EB) proteins associate with all growing microtubule plus ends throughout the cell cycle and serve as adaptors for diverse +TIPs that control microtubule dynamics and interactions with other intracellular structures.3 Because binding of many +TIPs to EB1 and thus microtubule-end association is switched off by mitotic phosphorylation,4-6 the mitotic function of EBs remains poorly understood. To analyze how EB1 and associated +TIPs on different spindle microtubule populations contribute to mitotic spindle dynamics, we use a light-sensitive EB1 variant, π-EB1, that allows local, acute, and reversible inactivation of +TIP association with growing microtubule ends in live cells.7 We find that acute π-EB1 photoinactivation results in rapid and reversible metaphase spindle shortening and transient relaxation of tension across the central spindle. However, in contrast to interphase, π-EB1 photoinactivation does not inhibit microtubule growth in metaphase but instead increases astral microtubule length and number. Yet in the absence of EB1 activity, astral microtubules fail to engage the cortical dynein/dynactin machinery, and spindle poles move away from regions of π-EB1 photoinactivation. In conclusion, our optogenetic approach reveals mitotic EB1 functions that remain hidden in genetic experiments, likely due to compensatory molecular systems regulating vertebrate spindle dynamics.
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Affiliation(s)
- Alessandro Dema
- Department of Cell & Tissue Biology, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143, USA
| | | | - Torsten Wittmann
- Department of Cell & Tissue Biology, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143, USA.
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16
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Kinesin-14 motors participate in a force balance at microtubule plus-ends to regulate dynamic instability. Proc Natl Acad Sci U S A 2022; 119:2108046119. [PMID: 35173049 PMCID: PMC8872730 DOI: 10.1073/pnas.2108046119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2022] [Indexed: 01/08/2023] Open
Abstract
Kinesin-14 motors represent an essential class of molecular motors that bind to microtubules and then walk toward the microtubule minus-end. However, whether these motors can interact with growing plus-ends of microtubules to impact the lengthening of microtubules remains unknown. We found that Kinesin-14 motors could bind to a protein that resides at growing microtubule plus-ends and then pull this protein away from the growing end. This interaction acted to disrupt microtubule growth and decrease microtubule lengths in cells, likely by exerting minus-end–directed forces at the microtubule tip to alter the configuration of the growing microtubule plus-end. This work demonstrates general principles for the diverse roles that force-generating molecular motors can play in regulating cellular processes. Kinesin-14 molecular motors represent an essential class of proteins that bind microtubules and walk toward their minus-ends. Previous studies have described important roles for Kinesin-14 motors at microtubule minus-ends, but their role in regulating plus-end dynamics remains controversial. Kinesin-14 motors have been shown to bind the EB family of microtubule plus-end binding proteins, suggesting that these minus-end–directed motors could interact with growing microtubule plus-ends. In this work, we explored the role of minus-end–directed Kinesin-14 motor forces in controlling plus-end microtubule dynamics. In cells, a Kinesin-14 mutant with reduced affinity to EB proteins led to increased microtubule lengths. Cell-free biophysical microscopy assays were performed using Kinesin-14 motors and an EB family marker of growing microtubule plus-ends, Mal3, which revealed that when Kinesin-14 motors bound to Mal3 at growing microtubule plus-ends, the motors subsequently walked toward the minus-end, and Mal3 was pulled away from the growing microtubule tip. Strikingly, these interactions resulted in an approximately twofold decrease in the expected postinteraction microtubule lifetime. Furthermore, generic minus-end–directed tension forces, generated by tethering growing plus-ends to the coverslip using λ-DNA, led to an approximately sevenfold decrease in the expected postinteraction microtubule growth length. In contrast, the inhibition of Kinesin-14 minus-end–directed motility led to extended tip interactions and to an increase in the expected postinteraction microtubule lifetime, indicating that plus-ends were stabilized by nonmotile Kinesin-14 motors. Together, we find that Kinesin-14 motors participate in a force balance at microtubule plus-ends to regulate microtubule lengths in cells.
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17
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Shen A, Liu L, Huang Y, Shen Z, Wu M, Chen X, Wu X, Lin X, Chen Y, Li L, Cheng Y, Chu J, Sferra TJ, Wei L, Zhuang Q, Peng J. Down-Regulating HAUS6 Suppresses Cell Proliferation by Activating the p53/p21 Pathway in Colorectal Cancer. Front Cell Dev Biol 2022; 9:772077. [PMID: 35096810 PMCID: PMC8790508 DOI: 10.3389/fcell.2021.772077] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 12/24/2021] [Indexed: 12/15/2022] Open
Abstract
Background: HAUS6 participates in microtubule-dependent microtubule amplification, but its role in malignancies including colorectal cancer (CRC) has not been explored. We therefore assessed the potential oncogenic activities of HAUS6 in CRC. Results: HAUS6 mRNA and protein expression is higher in CRC tissues, and high HAUS6 expression is correlated with shorter overall survival in CRC patients. HAUS6 knockdown in CRC cell lines suppressed cell growth in vitro and in vivo by inhibiting cell viability, survival and arresting cell cycle progression at G0/G1, while HAUS6 over-expression increased cell viability. We showed that these effects are dependent on activation of the p53/p21 signalling pathway by reducing p53 and p21 degradation. Moreover, combination of HAUS6 knockdown and 5-FU treatment further enhanced the suppression of cell proliferation of CRC cells by increasing activation of the p53/p21 pathway. Conclusion: Our study highlights a potential oncogenic role for HAUS6 in CRC. Targeting HAUS6 may be a promising novel prognostic marker and chemotherapeutic target for treating CRC patients.
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Affiliation(s)
- Aling Shen
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Liya Liu
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Yue Huang
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Zhiqing Shen
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Meizhu Wu
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Xiaoping Chen
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Xiangyan Wu
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Xiaoying Lin
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Youqin Chen
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China.,Department of Pediatrics, Case Western Reserve University School of Medicine, Rainbow Babies and Children's Hospital, Cleveland, OH, United States
| | - Li Li
- Department of Health Management, Fujian Provincial Hospital, Fuzhou, China
| | - Ying Cheng
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Jianfeng Chu
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Thomas J Sferra
- Department of Health Management, Fujian Provincial Hospital, Fuzhou, China
| | - Lihui Wei
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Qunchuan Zhuang
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Jun Peng
- Academy of Integrative Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine in Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
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18
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Atomic force microscopy reveals distinct protofilament-scale structural dynamics in depolymerizing microtubule arrays. Proc Natl Acad Sci U S A 2022; 119:2115708119. [PMID: 35101922 PMCID: PMC8812519 DOI: 10.1073/pnas.2115708119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2021] [Indexed: 12/01/2022] Open
Abstract
One cannot help but marvel at the precise organization of microtubule polymers in cellular structures such as the axoneme and the spindle. However, our understanding of the biochemical mechanisms that sculpt these arrays comes largely from in vitro experiments with a small number (one or two) of microtubules. This is somewhat akin to studying the architecture of multilane highways by studying one-lane streets. Here, we directly visualize depolymerizing microtubule arrays at individual microtubule and protofilament resolution using atomic force microscopy. Our results reveal differences in microtubule depolymerase activity and provide insights into how these differences in enzymatic activity on the nanometer scale can result in the differential remodeling of multimicrotubule arrays on the micron-length scale. The dynamic reorganization of microtubule-based cellular structures, such as the spindle and the axoneme, fundamentally depends on the dynamics of individual polymers within multimicrotubule arrays. A major class of enzymes implicated in both the complete demolition and fine size control of microtubule-based arrays are depolymerizing kinesins. How different depolymerases differently remodel microtubule arrays is poorly understood. A major technical challenge in addressing this question is that existing optical or electron-microscopy methods lack the spatial-temporal resolution to observe the dynamics of individual microtubules within larger arrays. Here, we use atomic force microscopy (AFM) to image depolymerizing arrays at single-microtubule and protofilament resolution. We discover previously unseen modes of microtubule array destabilization by conserved depolymerases. We find that the kinesin-13 MCAK mediates asynchronous protofilament depolymerization and lattice-defect propagation, whereas the kinesin-8 Kip3p promotes synchronous protofilament depolymerization. Unexpectedly, MCAK can depolymerize the highly stable axonemal doublets, but Kip3p cannot. We propose that distinct protofilament-level activities underlie the functional dichotomy of depolymerases, resulting in either large-scale destabilization or length regulation of microtubule arrays. Our work establishes AFM as a powerful strategy to visualize microtubule dynamics within arrays and reveals how nanometer-scale substrate specificity leads to differential remodeling of micron-scale cytoskeletal structures.
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19
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Sun M, Jia M, Ren H, Yang B, Chi W, Xin G, Jiang Q, Zhang C. NuMA regulates mitotic spindle assembly, structural dynamics and function via phase separation. Nat Commun 2021; 12:7157. [PMID: 34887424 PMCID: PMC8660824 DOI: 10.1038/s41467-021-27528-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 11/23/2021] [Indexed: 12/21/2022] Open
Abstract
A functional mitotic spindle is essential for accurate chromosome congression and segregation during cell proliferation; however, the underlying mechanisms of its assembly remain unclear. Here we show that NuMA regulates this assembly process via phase separation regulated by Aurora A. NuMA undergoes liquid-liquid phase separation during mitotic entry and KifC1 facilitates NuMA condensates concentrating on spindle poles. Phase separation of NuMA is mediated by its C-terminus, whereas its dynein-dynactin binding motif also facilitates this process. Phase-separated NuMA droplets concentrate tubulins, bind microtubules, and enrich crucial regulators, including Kif2A, at the spindle poles, which then depolymerizes spindle microtubules and promotes poleward spindle microtubule flux for spindle assembly and structural dynamics. In this work, we show that NuMA orchestrates mitotic spindle assembly, structural dynamics and function via liquid-liquid phase separation regulated by Aurora A phosphorylation.
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Affiliation(s)
- Mengjie Sun
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, 100871, Beijing, China
| | - Mingkang Jia
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, 100871, Beijing, China
| | - He Ren
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, 100871, Beijing, China
| | - Biying Yang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, 100871, Beijing, China
| | - Wangfei Chi
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, 100871, Beijing, China
| | - Guangwei Xin
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, 100871, Beijing, China
| | - Qing Jiang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, 100871, Beijing, China
| | - Chuanmao Zhang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, 100871, Beijing, China.
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20
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Uzsoy ASM, Zareiesfandabadi P, Jennings J, Kemper AF, Elting MW. Automated tracking of S. pombe spindle elongation dynamics. J Microsc 2021; 284:83-94. [PMID: 34152622 PMCID: PMC8446324 DOI: 10.1111/jmi.13044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 06/18/2021] [Indexed: 01/11/2023]
Abstract
The mitotic spindle is a microtubule-based machine that pulls the two identical sets of chromosomes to opposite ends of the cell during cell division. The fission yeast Schizosaccharomyces pombe is an important model organism for studying mitosis due to its simple, stereotyped spindle structure and well-established genetic toolset. S. pombe spindle length is a useful metric for mitotic progression, but manually tracking spindle ends in each frame to measure spindle length over time is laborious and can limit experimental throughput. We have developed an ImageJ plugin that can automatically track S. pombe spindle length over time and replace manual or semi-automated tracking of spindle elongation dynamics. Using an algorithm that detects the principal axis of the spindle and then finds its ends, we reliably track the length of the spindle as the cell divides. The plugin integrates with existing ImageJ features, exports its data for further analysis outside of ImageJ and does not require any programming by the user. Thus, the plugin provides an accessible tool for quantification of S. pombe spindle length that will allow automatic analysis of large microscopy data sets and facilitate screening for effects of cell biological perturbations on mitotic progression.
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Affiliation(s)
- Ana Sofía M. Uzsoy
- Department of Physics, North Carolina State University, Raleigh, NC 27695
- Department of Computer Science, North Carolina State University, Raleigh, NC 27695
| | | | - Jamie Jennings
- Department of Computer Science, North Carolina State University, Raleigh, NC 27695
| | | | - Mary Williard Elting
- Department of Physics, North Carolina State University, Raleigh, NC 27695
- Quantitative and Computational Developmental Biology Cluster, North Carolina State University, Raleigh, NC 27695
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21
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Campos Medina MA, Iemura K, Kimura A, Tanaka K. A mathematical model of kinetochore-microtubule attachment regulated by Aurora A activity gradient describes chromosome oscillation and correction of erroneous attachments. Biomed Res 2021; 42:203-219. [PMID: 34544996 DOI: 10.2220/biomedres.42.203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Chromosome oscillation during metaphase is attenuated in cancer cell lines, concomitant with the reduction of Aurora A activity on kinetochores, which results in reduced mitotic fidelity. To verify the correlation between Aurora A activity, chromosome oscillation, and error correction efficiency, we developed a mathematical model of kinetochore-microtubule dynamics, based on stochastic attachment/detachment events regulated by Aurora A activity gradient centered at spindle poles. The model accurately reproduced the oscillatory movements of chromosomes, which were suppressed not only when Aurora A activity was inhibited, but also when it was upregulated, mimicking the situation in cancer cells. Our simulation also predicted efficient correction of erroneous attachments through chromosome oscillation, which was hampered by both inhibition and upregulation of Aurora A activity. Our model provides a framework to understand the physiological role of chromosome oscillation in the correction of erroneous attachments that is intrinsically related to Aurora A activity.
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Affiliation(s)
- Manuel Alejandro Campos Medina
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University.,Department of Systemic Cell Biology, Max Planck Institute for Molecular Physiology
| | - Kenji Iemura
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University
| | - Akatsuki Kimura
- Cell Architecture Laboratory, Department of Chromosome Science, National Institute of Genetics; Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI)
| | - Kozo Tanaka
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University
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22
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Mani N, Jiang S, Neary AE, Wijeratne SS, Subramanian R. Differential regulation of single microtubules and bundles by a three-protein module. Nat Chem Biol 2021; 17:964-974. [PMID: 34083810 PMCID: PMC8387365 DOI: 10.1038/s41589-021-00800-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 04/19/2021] [Indexed: 12/15/2022]
Abstract
A remarkable feature of the microtubule cytoskeleton is co-existence of sub-populations having different dynamic properties. A prominent example is the anaphase spindle, where stable antiparallel bundles exist alongside dynamic microtubules and provide spatial cues for cytokinesis. How are dynamics of spatially proximal arrays differentially regulated? We reconstitute a minimal system of three midzone proteins: microtubule-crosslinker PRC1, and its interactors CLASP1 and Kif4A, proteins that promote and suppress microtubule elongation, respectively. We find their collective activity promotes elongation of single microtubules, while simultaneously stalling polymerization of crosslinked bundles. This differentiation arises from (i) Strong rescue activity of CLASP1, which overcomes weaker effects of Kif4A on single microtubules, (ii) Lower microtubule and PRC1-binding affinity of CLASP1, which permit dominance of Kif4A at overlaps. In addition to canonical mechanisms where antagonistic regulators set microtubule lengths, our findings illuminate design principles by which collective regulator activity creates microenvironments of arrays with distinct dynamic properties.
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Affiliation(s)
- Nandini Mani
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Shuo Jiang
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Alex E Neary
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
| | - Sithara S Wijeratne
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Radhika Subramanian
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA. .,Department of Genetics, Harvard Medical School, Boston, MA, USA.
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23
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Barisic M, Rajendraprasad G, Steblyanko Y. The metaphase spindle at steady state - Mechanism and functions of microtubule poleward flux. Semin Cell Dev Biol 2021; 117:99-117. [PMID: 34053864 DOI: 10.1016/j.semcdb.2021.05.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/13/2021] [Accepted: 05/13/2021] [Indexed: 11/24/2022]
Abstract
The mitotic spindle is a bipolar cellular structure, built from tubulin polymers, called microtubules, and interacting proteins. This macromolecular machine orchestrates chromosome segregation, thereby ensuring accurate distribution of genetic material into the two daughter cells during cell division. Powered by GTP hydrolysis upon tubulin polymerization, the microtubule ends exhibit a metastable behavior known as the dynamic instability, during which they stochastically switch between the growth and shrinkage phases. In the context of the mitotic spindle, dynamic instability is furthermore regulated by microtubule-associated proteins and motor proteins, which enables the spindle to undergo profound changes during mitosis. This highly dynamic behavior is essential for chromosome capture and congression in prometaphase, as well as for chromosome alignment to the spindle equator in metaphase and their segregation in anaphase. In this review we focus on the mechanisms underlying microtubule dynamics and sliding and their importance for the maintenance of shape, structure and dynamics of the metaphase spindle. We discuss how these spindle properties are related to the phenomenon of microtubule poleward flux, highlighting its highly cooperative molecular basis and role in keeping the metaphase spindle at a steady state.
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Affiliation(s)
- Marin Barisic
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Strandboulevarden 49, 2100 Copenhagen, Denmark; Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
| | - Girish Rajendraprasad
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Strandboulevarden 49, 2100 Copenhagen, Denmark
| | - Yulia Steblyanko
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Strandboulevarden 49, 2100 Copenhagen, Denmark
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24
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Nunes V, Ferreira JG. From the cytoskeleton to the nucleus: An integrated view on early spindle assembly. Semin Cell Dev Biol 2021; 117:42-51. [PMID: 33726956 DOI: 10.1016/j.semcdb.2021.03.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 03/09/2021] [Accepted: 03/10/2021] [Indexed: 12/01/2022]
Abstract
Accurate chromosome segregation requires a complete restructuring of cellular organization. Microtubules remodel to assemble a mitotic spindle and the actin cytoskeleton rearranges to form a stiff actomyosin cortex. These cytoplasmic events must be spatially and temporally coordinated with mitotic chromosome condensation and nuclear envelope permeabilization, in order to ensure mitotic timing and fidelity. Here, we discuss the main cytoskeletal and nuclear events that occur during mitotic entry in proliferating animal cells, focusing on their coordinated contribution for early mitotic spindle assembly. We will also explore recent progress in understanding their regulatory biochemical and mechanical pathways.
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Affiliation(s)
- Vanessa Nunes
- Instituto de Investigação e Inovação em Saúde - i3S, University of Porto, Porto, Portugal; BiotechHealth PhD Programe, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), University of Porto, Porto, Portugal
| | - Jorge G Ferreira
- Instituto de Investigação e Inovação em Saúde - i3S, University of Porto, Porto, Portugal; Departamento de Biomedicina, Faculdade de Medicina, University of Porto, Porto, Portugal.
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25
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Spindle scaling mechanisms. Essays Biochem 2021; 64:383-396. [PMID: 32501481 DOI: 10.1042/ebc20190064] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/11/2020] [Accepted: 05/12/2020] [Indexed: 02/02/2023]
Abstract
The mitotic spindle robustly scales with cell size in a plethora of different organisms. During development and throughout evolution, the spindle adjusts to cell size in metazoans and yeast in order to ensure faithful chromosome separation. Spindle adjustment to cell size occurs by the scaling of spindle length, spindle shape and the velocity of spindle assembly and elongation. Different mechanisms, depending on spindle structure and organism, account for these scaling relationships. The limited availability of critical spindle components, protein gradients, sequestration of spindle components, or post-translational modification and differential expression levels have been implicated in the regulation of spindle length and the spindle assembly/elongation velocity in a cell size-dependent manner. In this review, we will discuss the phenomenon and mechanisms of spindle length, spindle shape and spindle elongation velocity scaling with cell size.
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26
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Nehlig A, Seiler C, Steblyanko Y, Dingli F, Arras G, Loew D, Welburn J, Prigent C, Barisic M, Nahmias C. Reciprocal regulation of Aurora kinase A and ATIP3 in the control of metaphase spindle length. Cell Mol Life Sci 2021; 78:1765-1779. [PMID: 32789689 PMCID: PMC11072152 DOI: 10.1007/s00018-020-03614-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 07/18/2020] [Accepted: 08/07/2020] [Indexed: 12/16/2022]
Abstract
Maintaining the integrity of the mitotic spindle in metaphase is essential to ensure normal cell division. We show here that depletion of microtubule-associated protein ATIP3 reduces metaphase spindle length. Mass spectrometry analyses identified the microtubule minus-end depolymerizing kinesin Kif2A as an ATIP3 binding protein. We show that ATIP3 controls metaphase spindle length by interacting with Kif2A and its partner Dda3 in an Aurora kinase A-dependent manner. In the absence of ATIP3, Kif2A and Dda3 accumulate at spindle poles, which is consistent with reduced poleward microtubule flux and shortening of the spindle. ATIP3 silencing also limits Aurora A localization to the poles. Transfection of GFP-Aurora A, but not kinase-dead mutant, rescues the phenotype, indicating that ATIP3 maintains Aurora A activity on the poles to control Kif2A targeting and spindle size. Collectively, these data emphasize the pivotal role of Aurora kinase A and its mutual regulation with ATIP3 in controlling spindle length.
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Affiliation(s)
- Anne Nehlig
- Inserm U981, Department of Molecular Medicine, Gustave Roussy Cancer Center, 114 rue Edouard Vaillant, 94800, Villejuif, France
- LabEx LERMIT, Université Paris Saclay, 92296, Châtenay-Malabry, France
- Institut Gustave Roussy, Inserm, Biomarqueurs prédictifs et nouvelles stratégies thérapeutiques en oncologie, Université Paris-Saclay, 94800, Villejuif, France
| | - Cynthia Seiler
- Inserm U981, Department of Molecular Medicine, Gustave Roussy Cancer Center, 114 rue Edouard Vaillant, 94800, Villejuif, France
- LabEx LERMIT, Université Paris Saclay, 92296, Châtenay-Malabry, France
- Institut Gustave Roussy, Inserm, Biomarqueurs prédictifs et nouvelles stratégies thérapeutiques en oncologie, Université Paris-Saclay, 94800, Villejuif, France
| | - Yulia Steblyanko
- Cell Division Laboratory, Danish Cancer Society Research Center, 2100, Copenhagen, Denmark
| | - Florent Dingli
- Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, 75248, Paris Cedex 05, France
| | - Guillaume Arras
- Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, 75248, Paris Cedex 05, France
| | - Damarys Loew
- Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, 75248, Paris Cedex 05, France
| | - Julie Welburn
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, Scotland, UK
| | - Claude Prigent
- Institut de Génétique et Développement de Rennes (IGDR), Unité CNRS, UMR 6290, Université de Rennes, 35043, Rennes, France
| | - Marin Barisic
- Cell Division Laboratory, Danish Cancer Society Research Center, 2100, Copenhagen, Denmark
- Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Clara Nahmias
- Inserm U981, Department of Molecular Medicine, Gustave Roussy Cancer Center, 114 rue Edouard Vaillant, 94800, Villejuif, France.
- LabEx LERMIT, Université Paris Saclay, 92296, Châtenay-Malabry, France.
- Institut Gustave Roussy, Inserm, Biomarqueurs prédictifs et nouvelles stratégies thérapeutiques en oncologie, Université Paris-Saclay, 94800, Villejuif, France.
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27
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Farhadifar R, Yu CH, Fabig G, Wu HY, Stein DB, Rockman M, Müller-Reichert T, Shelley MJ, Needleman DJ. Stoichiometric interactions explain spindle dynamics and scaling across 100 million years of nematode evolution. eLife 2020; 9:e55877. [PMID: 32966209 PMCID: PMC7511230 DOI: 10.7554/elife.55877] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Accepted: 08/31/2020] [Indexed: 01/17/2023] Open
Abstract
The spindle shows remarkable diversity, and changes in an integrated fashion, as cells vary over evolution. Here, we provide a mechanistic explanation for variations in the first mitotic spindle in nematodes. We used a combination of quantitative genetics and biophysics to rule out broad classes of models of the regulation of spindle length and dynamics, and to establish the importance of a balance of cortical pulling forces acting in different directions. These experiments led us to construct a model of cortical pulling forces in which the stoichiometric interactions of microtubules and force generators (each force generator can bind only one microtubule), is key to explaining the dynamics of spindle positioning and elongation, and spindle final length and scaling with cell size. This model accounts for variations in all the spindle traits we studied here, both within species and across nematode species spanning over 100 million years of evolution.
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Affiliation(s)
- Reza Farhadifar
- Department of Molecular and Cellular Biology and School of Engineering and Applied Sciences, Harvard UniversityCambridgeUnited States
- Center for Computational Biology, Flatiron InstituteNew YorkUnited States
| | - Che-Hang Yu
- Department of Molecular and Cellular Biology and School of Engineering and Applied Sciences, Harvard UniversityCambridgeUnited States
| | - Gunar Fabig
- Experimental Center, Faculty of Medicine Carl Gustav CarusDresdenGermany
| | - Hai-Yin Wu
- Department of Molecular and Cellular Biology and School of Engineering and Applied Sciences, Harvard UniversityCambridgeUnited States
| | - David B Stein
- Center for Computational Biology, Flatiron InstituteNew YorkUnited States
| | - Matthew Rockman
- Department of Biology and Center for Genomics & Systems Biology, New York UniversityNew YorkUnited States
| | | | - Michael J Shelley
- Center for Computational Biology, Flatiron InstituteNew YorkUnited States
- Courant Institute, New York UniversityNew YorkUnited States
| | - Daniel J Needleman
- Department of Molecular and Cellular Biology and School of Engineering and Applied Sciences, Harvard UniversityCambridgeUnited States
- Center for Computational Biology, Flatiron InstituteNew YorkUnited States
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28
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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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29
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Zheng F, Dong F, Yu S, Li T, Jian Y, Nie L, Fu C. Klp2 and Ase1 synergize to maintain meiotic spindle stability during metaphase I. J Biol Chem 2020; 295:13287-13298. [PMID: 32723864 DOI: 10.1074/jbc.ra120.012905] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 07/24/2020] [Indexed: 11/06/2022] Open
Abstract
The spindle apparatus segregates bi-oriented sister chromatids during mitosis but mono-oriented homologous chromosomes during meiosis I. It has remained unclear if similar molecular mechanisms operate to regulate spindle dynamics during mitosis and meiosis I. Here, we employed live-cell microscopy to compare the spindle dynamics of mitosis and meiosis I in fission yeast cells and demonstrated that the conserved kinesin-14 motor Klp2 plays a specific role in maintaining metaphase spindle length during meiosis I but not during mitosis. Moreover, the maintenance of metaphase spindle stability during meiosis I requires the synergism between Klp2 and the conserved microtubule cross-linker Ase1, as the absence of both proteins causes exacerbated defects in metaphase spindle stability. The synergism is not necessary for regulating mitotic spindle dynamics. Hence, our work reveals a new molecular mechanism underlying meiotic spindle dynamics and provides insights into understanding differential regulation of meiotic and mitotic events.
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Affiliation(s)
- Fan Zheng
- Ministry of Education Key Laboratory for Membrane-less Organelles & Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Fenfen Dong
- Ministry of Education Key Laboratory for Membrane-less Organelles & Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Shuo Yu
- Ministry of Education Key Laboratory for Membrane-less Organelles & Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Tianpeng Li
- Ministry of Education Key Laboratory for Membrane-less Organelles & Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yanze Jian
- Ministry of Education Key Laboratory for Membrane-less Organelles & Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Lingyun Nie
- Ministry of Education Key Laboratory for Membrane-less Organelles & Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Chuanhai Fu
- Ministry of Education Key Laboratory for Membrane-less Organelles & Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.
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30
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Abstract
The mitotic spindle is a dynamic and complex cellular structure made of microtubules and associated proteins. Although the general localization of most proteins has been identified, the arrangement of the microtubules in the mitotic spindle and precise localization of various proteins are still under intensive research. However, techniques used previously to decipher such puzzles are resolution limited or require complex microscopy systems. On the other hand, expansion microscopy is a novel super-resolution microscopy technique that uses physical expansion of fixed specimens to allow features closer than the diffraction limit of light (~250nm) to become resolvable in the expanded specimen on a conventional confocal microscope. This chapter focuses on expansion microscopy of the mitotic spindle, specifically using tubulin labeling to visualize all microtubule subpopulations within the spindle. Furthermore, we discuss a protocol for expansion of GFP-tagged proteins, such as protein regulator of cytokinesis 1 (PRC1). We also discuss various approaches for image analysis pointing out main advantages of expansion microscopy when compared to previously used techniques. This approach is currently used in our laboratory to study the architecture of the microtubules in the mitotic spindle after perturbations of various proteins important for the structural and dynamical properties of the mitotic spindle.
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31
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Warren JD, Orr B, Compton DA. A comparative analysis of methods to measure kinetochore-microtubule attachment stability. Methods Cell Biol 2020; 158:91-116. [PMID: 32423652 PMCID: PMC7727308 DOI: 10.1016/bs.mcb.2020.01.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/18/2023]
Abstract
During mitosis, spindle microtubules dynamically attach to and detach from kinetochores in a precise and regulated fashion. To ensure mitotic fidelity, kinetochore-microtubule (k-MT) attachments must be stable enough to satisfy the spindle assembly checkpoint (SAC), but sufficiently unstable to facilitate the correction of maloriented attachments. Different methods are available to assess k-MT stability in both live and fixed cells, but a comparative survey of these methods has not yet been reported. Here, we evaluate several quantitative and semiquantitative methods for determining k-MT stability and apply each technique to illustrate changes in spindle microtubule dynamics upon perturbation with physiologically relevant concentrations of microtubule stabilizing (Taxol) and destabilizing (UMK57 and nocodazole) compounds. We discuss the utility of each technique for defining specific features of spindle microtubule dynamics and k-MT attachment stability.
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Affiliation(s)
- Jessica D Warren
- Department of Biochemistry and Cell Biology, Geisel School of Medicine, Hanover, NH, United States; Norris Cotton Cancer Center, Lebanon, NH, United States
| | - Bernardo Orr
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Duane A Compton
- Department of Biochemistry and Cell Biology, Geisel School of Medicine, Hanover, NH, United States; Norris Cotton Cancer Center, Lebanon, NH, United States.
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32
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Edelmaier C, Lamson AR, Gergely ZR, Ansari S, Blackwell R, McIntosh JR, Glaser MA, Betterton MD. Mechanisms of chromosome biorientation and bipolar spindle assembly analyzed by computational modeling. eLife 2020; 9:48787. [PMID: 32053104 PMCID: PMC7311174 DOI: 10.7554/elife.48787] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 02/12/2020] [Indexed: 01/19/2023] Open
Abstract
The essential functions required for mitotic spindle assembly and chromosome biorientation and segregation are not fully understood, despite extensive study. To illuminate the combinations of ingredients most important to align and segregate chromosomes and simultaneously assemble a bipolar spindle, we developed a computational model of fission-yeast mitosis. Robust chromosome biorientation requires progressive restriction of attachment geometry, destabilization of misaligned attachments, and attachment force dependence. Large spindle length fluctuations can occur when the kinetochore-microtubule attachment lifetime is long. The primary spindle force generators are kinesin-5 motors and crosslinkers in early mitosis, while interkinetochore stretch becomes important after biorientation. The same mechanisms that contribute to persistent biorientation lead to segregation of chromosomes to the poles after anaphase onset. This model therefore provides a framework to interrogate key requirements for robust chromosome biorientation, spindle length regulation, and force generation in the spindle. Before a cell divides, it must make a copy of its genetic material and then promptly split in two. This process, called mitosis, is coordinated by many different molecular machines. The DNA is copied, then the duplicated chromosomes line up at the middle of the cell. Next, an apparatus called the mitotic spindle latches onto the chromosomes before pulling them apart. The mitotic spindle is a bundle of long, thin filaments called microtubules. It attaches to chromosomes at the kinetochore, the point where two copied chromosomes are cinched together in their middle. Proper cell division is vital for the healthy growth of all organisms, big and small, and yet some parts of the process remain poorly understood despite extensive study. Specifically, there is more to learn about how the mitotic spindle self-assembles, and how microtubules and kinetochores work together to correctly orient and segregate chromosomes into two sister cells. These nanoscale processes are happening a hundred times a minute, so computer simulations are a good way to test what we know. Edelmaier et al. developed a computer model to simulate cell division in fission yeast, a species of yeast often used to study fundamental processes in the cell. The model simulates how the mitotic spindle assembles, how its microtubules attach to the kinetochore and the force required to pull two sister chromosomes apart. Building the simulation involved modelling interactions between the mitotic spindle and kinetochore, their movement and forces applied. To test its accuracy, model simulations were compared to recordings of the mitotic spindle – including its length, structure and position – imaged from dividing yeast cells. Running the simulation, Edelmaier et al. found that several key effects are essential for the proper movement of chromosomes in mitosis. This includes holding chromosomes in the correct orientation as the mitotic spindle assembles and controlling the relative position of microtubules as they attach to the kinetochore. Misaligned attachments must also be readily deconstructed and corrected to prevent any errors. The simulations also showed that kinetochores must begin to exert more force (to separate the chromosomes) once the mitotic spindle is attached correctly. Altogether, these findings improve the current understanding of how the mitotic spindle and its counterparts control cell division. Errors in chromosome segregation are associated with birth defects and cancer in humans, and this new simulation could potentially now be used to help make predictions about how to correct mistakes in the process.
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Affiliation(s)
| | - Adam R Lamson
- Department of Physics, University of Colorado Boulder, Boulder, United States
| | - Zachary R Gergely
- Department of Physics, University of Colorado Boulder, Boulder, United States.,Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, United States
| | - Saad Ansari
- Department of Physics, University of Colorado Boulder, Boulder, United States
| | - Robert Blackwell
- Department of Physics, University of Colorado Boulder, Boulder, United States
| | - J Richard McIntosh
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, United States
| | - Matthew A Glaser
- Department of Physics, University of Colorado Boulder, Boulder, United States
| | - Meredith D Betterton
- Department of Physics, University of Colorado Boulder, Boulder, United States.,Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, United States
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33
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Bodrug T, Wilson-Kubalek EM, Nithianantham S, Thompson AF, Alfieri A, Gaska I, Major J, Debs G, Inagaki S, Gutierrez P, Gheber L, McKenney RJ, Sindelar CV, Milligan R, Stumpff J, Rosenfeld SS, Forth ST, Al-Bassam J. The kinesin-5 tail domain directly modulates the mechanochemical cycle of the motor domain for anti-parallel microtubule sliding. eLife 2020; 9:e51131. [PMID: 31958056 PMCID: PMC7015671 DOI: 10.7554/elife.51131] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 01/16/2020] [Indexed: 12/29/2022] Open
Abstract
Kinesin-5 motors organize mitotic spindles by sliding apart microtubules. They are homotetramers with dimeric motor and tail domains at both ends of a bipolar minifilament. Here, we describe a regulatory mechanism involving direct binding between tail and motor domains and its fundamental role in microtubule sliding. Kinesin-5 tails decrease microtubule-stimulated ATP-hydrolysis by specifically engaging motor domains in the nucleotide-free or ADP states. Cryo-EM reveals that tail binding stabilizes an open motor domain ATP-active site. Full-length motors undergo slow motility and cluster together along microtubules, while tail-deleted motors exhibit rapid motility without clustering. The tail is critical for motors to zipper together two microtubules by generating substantial sliding forces. The tail is essential for mitotic spindle localization, which becomes severely reduced in tail-deleted motors. Our studies suggest a revised microtubule-sliding model, in which kinesin-5 tails stabilize motor domains in the microtubule-bound state by slowing ATP-binding, resulting in high-force production at both homotetramer ends.
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Affiliation(s)
- Tatyana Bodrug
- Department of Molecular and Cellular BiologyUniversity of California, DavisDavisUnited States
| | - Elizabeth M Wilson-Kubalek
- Department of Integrative Structural and Computational BiologyScripps Research InstituteLa JollaUnited States
| | - Stanley Nithianantham
- Department of Molecular and Cellular BiologyUniversity of California, DavisDavisUnited States
| | - Alex F Thompson
- Department of Molecular Physiology and BiophysicsUniversity of VermontBurlingtonUnited States
| | - April Alfieri
- Department of Biological SciencesRensselaer Polytechnic InstituteTroyUnited States
| | - Ignas Gaska
- Department of Biological SciencesRensselaer Polytechnic InstituteTroyUnited States
| | - Jennifer Major
- Department of Cancer BiologyLerner Research Institute, Cleveland ClinicLorainUnited States
- Department of PharmacologyMayo ClinicJacksonvilleUnited States
| | - Garrett Debs
- Department of Molecular Biophysics and BiochemistryYale UniversityNew HavenUnited States
| | - Sayaka Inagaki
- Department of PharmacologyMayo ClinicJacksonvilleUnited States
| | - Pedro Gutierrez
- Department of Molecular and Cellular BiologyUniversity of California, DavisDavisUnited States
| | - Larisa Gheber
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and TechnologyBen-Gurion University of the NegevNegevIsrael
| | - Richard J McKenney
- Department of Molecular and Cellular BiologyUniversity of California, DavisDavisUnited States
| | | | - Ronald Milligan
- Department of Integrative Structural and Computational BiologyScripps Research InstituteLa JollaUnited States
| | - Jason Stumpff
- Department of Molecular Physiology and BiophysicsUniversity of VermontBurlingtonUnited States
| | - Steven S Rosenfeld
- Department of Cancer BiologyLerner Research Institute, Cleveland ClinicLorainUnited States
- Department of PharmacologyMayo ClinicJacksonvilleUnited States
| | - Scott T Forth
- Department of Biological SciencesRensselaer Polytechnic InstituteTroyUnited States
| | - Jawdat Al-Bassam
- Department of Molecular and Cellular BiologyUniversity of California, DavisDavisUnited States
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34
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Leary A, Sim S, Nazarova E, Shulist K, Genthial R, Yang SK, Bui KH, Francois P, Vogel J. Successive Kinesin-5 Microtubule Crosslinking and Sliding Promote Fast, Irreversible Formation of a Stereotyped Bipolar Spindle. Curr Biol 2019; 29:3825-3837.e3. [DOI: 10.1016/j.cub.2019.09.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 07/24/2019] [Accepted: 09/12/2019] [Indexed: 12/13/2022]
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35
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Miller KE, Session AM, Heald R. Kif2a Scales Meiotic Spindle Size in Hymenochirus boettgeri. Curr Biol 2019; 29:3720-3727.e5. [PMID: 31630945 DOI: 10.1016/j.cub.2019.08.073] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 08/13/2019] [Accepted: 08/29/2019] [Indexed: 10/25/2022]
Abstract
Size is a fundamental feature of biological systems that affects physiology at all levels. For example, the dynamic, microtubule-based spindle that mediates chromosome segregation scales to a wide range of cell sizes across different organisms and cell types. Xenopus frog species possess a variety of egg and meiotic spindle sizes, and differences in activities or levels of microtubule-associated proteins in the egg cytoplasm between Xenopus laevis and Xenopus tropicalis have been shown to account for spindle scaling [1]. Increased activity of the microtubule severing protein katanin scales the X. tropicalis spindle smaller compared to X. laevis [2], as do elevated levels of TPX2, a protein that enriches the cross-linking kinesin-5 motor Eg5 at spindle poles [3]. To examine the conservation of spindle scaling mechanisms more broadly across frog species, we have utilized the tiny, distantly related Pipid frog Hymenochirus boettgeri. We find that egg extracts from H. boettgeri form meiotic spindles similar in size to X. tropicalis but that TPX2 and katanin-mediated scaling is not conserved. Instead, the microtubule depolymerizing motor protein kif2a functions to modulate spindle size. H. boettgeri kif2a possesses an activating phosphorylation site that is absent from X. laevis. Comparison of katanin and kif2a phosphorylation sites across a variety of species revealed strong evolutionary conservation, with X. laevis and X. tropicalis possessing distinct and unique alterations. Our study highlights the diversity and complexity of spindle assembly and scaling mechanisms, indicating that there is more than one way to assemble a spindle of a particular size.
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Affiliation(s)
- Kelly E Miller
- Department of Molecular and Cell Biology, University of California, CA 94720, Berkeley, USA
| | - Adam M Session
- Department of Molecular and Cell Biology, University of California, CA 94720, Berkeley, USA
| | - Rebecca Heald
- Department of Molecular and Cell Biology, University of California, CA 94720, Berkeley, USA.
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36
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Nellikka RK, Sreeja JS, Dharmapal D, John R, Monteiro A, Macedo JC, Conde C, Logarinho E, Sunkel CE, Sengupta S. α-Fodrin is required for the organization of functional microtubules during mitosis. Cell Cycle 2019; 18:2713-2726. [PMID: 31455186 DOI: 10.1080/15384101.2019.1656476] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The cytoskeleton protein α-fodrin plays a major role in maintaining structural stability of membranes. It was also identified as part of the brain γ-tubulin ring complex, the major microtubule nucleator. Here, we investigated the requirement of α-fodrin for microtubule spindle assembly during mitotic progression. We found that α-fodrin depletion results in abnormal mitosis with uncongressed chromosomes, leading to prolonged activation of the spindle assembly checkpoint and a severe mitotic delay. Further, α-fodrin repression led to the formation of shortened spindles with unstable kinetochore-microtubule attachments. We also found that the mitotic kinesin CENP-E had reduced levels at kinetochores to likely account for the chromosome misalignment defects in α-fodrin-depleted cells. Importantly, we showed these cells to exhibit reduced levels of detyrosinated α-tubulin, which primarily drives CENP-E localization. Since proper microtubule dynamics and chromosome alignment are required for completion of normal mitosis, this study reveals an unforeseen role of α-fodrin in regulating mitotic progression. Future studies on these lines of observations should reveal important mechanistic insight for fodrin's involvement in cancer.
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Affiliation(s)
- Rohith Kumar Nellikka
- Cancer Research Program-III, Rajiv Gandhi Centre for Biotechnology, University of Kerala , Thiruvananthapuram , India
| | - Jamuna S Sreeja
- Cancer Research Program-III, Rajiv Gandhi Centre for Biotechnology, University of Kerala , Thiruvananthapuram , India
| | - Dhrishya Dharmapal
- Cancer Research Program-III, Rajiv Gandhi Centre for Biotechnology, University of Kerala , Thiruvananthapuram , India
| | - Rince John
- Cancer Research Program-III, Rajiv Gandhi Centre for Biotechnology, University of Kerala , Thiruvananthapuram , India
| | | | | | - Carlos Conde
- i3S-IBMC, Universidade do Porto , Porto , Portugal
| | | | - Claudio E Sunkel
- i3S-IBMC, Universidade do Porto , Porto , Portugal.,ICBAS-Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto , Porto , Portugal
| | - Suparna Sengupta
- Cancer Research Program-III, Rajiv Gandhi Centre for Biotechnology, University of Kerala , Thiruvananthapuram , India
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37
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Rieckhoff EM, Ishihara K, Brugués J. How to tune spindle size relative to cell size? Curr Opin Cell Biol 2019; 60:139-144. [PMID: 31377657 DOI: 10.1016/j.ceb.2019.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 06/17/2019] [Accepted: 06/17/2019] [Indexed: 12/20/2022]
Abstract
Cells need to regulate the size and shape of their organelles for proper function. For example, the mitotic spindle adapts its size to changes in cell size over several orders of magnitude, but we lack a mechanistic understanding of how this is achieved. Here, we review our current knowledge of how small and large spindles assemble and ask which microtubule-based biophysical processes (nucleation, polymerization dynamics, transport) may be responsible for spindle size regulation. Finally, we review possible cell-scale mechanisms that put spindle size under the regulation of cell size.
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Affiliation(s)
- Elisa Maria Rieckhoff
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, Germany; Center for Systems Biology Dresden, Dresden, Germany; Cluster of Excellence Physics of Life, TU Dresden, Dresden, Germany
| | - Keisuke Ishihara
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, Germany; Center for Systems Biology Dresden, Dresden, Germany; Cluster of Excellence Physics of Life, TU Dresden, Dresden, Germany
| | - Jan Brugués
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, Germany; Center for Systems Biology Dresden, Dresden, Germany; Cluster of Excellence Physics of Life, TU Dresden, Dresden, Germany.
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Kinesin-6 Klp9 plays motor-dependent and -independent roles in collaboration with Kinesin-5 Cut7 and the microtubule crosslinker Ase1 in fission yeast. Sci Rep 2019; 9:7336. [PMID: 31089172 PMCID: PMC6517423 DOI: 10.1038/s41598-019-43774-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 05/01/2019] [Indexed: 02/03/2023] Open
Abstract
Bipolar mitotic spindles play a critical part in accurate chromosome segregation. During late mitosis, spindle microtubules undergo drastic elongation in a process called anaphase B. Two kinesin motors, Kinesin-5 and Kinesin-6, are thought to generate outward forces to drive spindle elongation, and the microtubule crosslinker Ase1/PRC1 maintains structural integrity of antiparallel microtubules. However, how these three proteins orchestrate this process remains unknown. Here we explore the functional interplay among fission yeast Kinesin-5/Cut7, Kinesin-6/Klp9 and Ase1. Using total internal reflection fluorescence microscopy, we show that Klp9 forms homotetramers and that Klp9 is a processive plus end-directed motor. klp9Δase1Δ is synthetically lethal. Surprisingly, this lethality is not ascribable to the defective motor activity of Klp9; instead, it is dependent upon a nuclear localisation signal and coiled coil domains within the non-motor region. We isolated a cut7 mutant (cut7-122) that displays temperature sensitivity only in the absence of Klp9. Interestingly, cut7-122 alone is impaired in spindle elongation during anaphase B, and furthermore, cut7-122klp9Δ double mutants exhibit additive defects. We propose that Klp9 plays dual roles during anaphase B; one is motor-dependent that collaborates with Cut7 in force generation, while the other is motor-independent that ensures structural integrity of spindle microtubules together with Ase1.
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Hueschen CL, Galstyan V, Amouzgar M, Phillips R, Dumont S. Microtubule End-Clustering Maintains a Steady-State Spindle Shape. Curr Biol 2019; 29:700-708.e5. [PMID: 30744975 DOI: 10.1016/j.cub.2019.01.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 11/26/2018] [Accepted: 01/08/2019] [Indexed: 01/01/2023]
Abstract
Each time a cell divides, the microtubule cytoskeleton self-organizes into the metaphase spindle: an ellipsoidal steady-state structure that holds its stereotyped geometry despite microtubule turnover and internal stresses [1-6]. Regulation of microtubule dynamics, motor proteins, microtubule crosslinking, and chromatid cohesion can modulate spindle size and shape, and yet modulated spindles reach and hold a new steady state [7-11]. Here, we ask what maintains any spindle steady-state geometry. We report that clustering of microtubule ends by dynein and NuMA is essential for mammalian spindles to hold a steady-state shape. After dynein or NuMA deletion, the mitotic microtubule network is "turbulent"; microtubule bundles extend and bend against the cell cortex, constantly remodeling network shape. We find that spindle turbulence is driven by the homotetrameric kinesin-5 Eg5, and that acute Eg5 inhibition in turbulent spindles recovers spindle geometry and stability. Inspired by in vitro work on active turbulent gels of microtubules and kinesin [12, 13], we explore the kinematics of this in vivo turbulent network. We find that turbulent spindles display decreased nematic order and that motile asters distort the nematic director field. Finally, we see that turbulent spindles can drive both flow of cytoplasmic organelles and whole-cell movement-analogous to the autonomous motility displayed by droplet-encapsulated turbulent gels [12]. Thus, end-clustering by dynein and NuMA is required for mammalian spindles to reach a steady-state geometry, and in their absence Eg5 powers a turbulent microtubule network inside mitotic cells.
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Affiliation(s)
- Christina L Hueschen
- Department of Cell and Tissue Biology, UCSF, San Francisco, CA 94143, USA; Biomedical Sciences Graduate Program, UCSF, San Francisco, CA 94143, USA.
| | - Vahe Galstyan
- Biochemistry and Molecular Biophysics Option, California Institute of Technology, Pasadena, CA 91106, USA
| | - Meelad Amouzgar
- Department of Cell and Tissue Biology, UCSF, San Francisco, CA 94143, USA
| | - Rob Phillips
- Department of Physics, California Institute of Technology, Pasadena, CA 91106, USA; Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91106, USA
| | - Sophie Dumont
- Department of Cell and Tissue Biology, UCSF, San Francisco, CA 94143, USA; Biomedical Sciences Graduate Program, UCSF, San Francisco, CA 94143, USA; Department of Cellular and Molecular Pharmacology, UCSF, San Francisco, CA 94143, USA.
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40
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Kaibori Y, Saito Y, Nakayama Y. EphA2 phosphorylation at Ser897 by the Cdk1/MEK/ERK/RSK pathway regulates M-phase progression via maintenance of cortical rigidity. FASEB J 2019; 33:5334-5349. [PMID: 30668924 DOI: 10.1096/fj.201801519rr] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Successful cell division is accomplished by the proper formation of the mitotic spindle. Here, we show that EphA2 knockdown causes mitotic errors, including a delay in M-phase progression, asymmetric spindle positioning, multipolar spindles, and cell blebs. It has been known that EphA2 is phosphorylated at Tyr588, which is triggered by the ligand binding, and at Ser897 downstream of growth factor signaling. Upon mitotic entry, EphA2 is phosphorylated at Ser897, accompanied by a reduction in Tyr588 phosphorylation. This EphA2 phosphorylation at Ser897 is inhibited by MEK/ERK and 90 kDa ribosomal S6 kinase (RSK) inhibitors and is induced by the introduction of active cyclin-dependent kinase 1 (Cdk1) and cyclin B1. EphA2 knockdown-induced M-phase delay and cell blebs are rescued by wild type EphA2 expression but not by Ser897Ala mutant. The Ras homolog gene family member G (RhoG) guanine nucleotide exchange factor Ephexin4 interacts with EphA2 in a Ser897 phosphorylation-dependent manner, and its knockdown delays M-phase progression and causes RhoG delocalization. RhoG knockdown delays M-phase progression, and EphA2 knockdown-induced M-phase delay is partially rescued by the constitutively active RhoG mutant. These results suggest that, in EphA2-expressing cells, EphA2 phosphorylation at Ser897 participates in proper M-phase progression downstream of the Cdk1/MEK/ERK/RSK pathway because of its role in maintaining cortical rigidity via Ephexin4 and RhoG and thereby regulating mitotic spindle formation.-Kaibori, Y. Saito, Y., Nakayama, Y. EphA2 phosphorylation at Ser897 by the Cdk1/MEK/ERK/RSK pathway regulates M-phase progression via maintenance of cortical rigidity.
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Affiliation(s)
- Yuichiro Kaibori
- Department of Biochemistry and Molecular Biology, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Youhei Saito
- Department of Biochemistry and Molecular Biology, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Yuji Nakayama
- Department of Biochemistry and Molecular Biology, Kyoto Pharmaceutical University, Kyoto, Japan
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Olziersky AM, Smith CA, Burroughs N, McAinsh AD, Meraldi P. Mitotic live-cell imaging at different timescales. Methods Cell Biol 2018; 145:1-27. [PMID: 29957199 DOI: 10.1016/bs.mcb.2018.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mitosis is a highly dynamic and choreographed process in which chromosomes are captured by the mitotic spindle and physically segregated into the two daughter cells to ensure faithful transmission of the genetic material. Live-cell fluorescence microscopy enables these dynamics to be analyzed over diverse temporal scales. Here we present the methodologies to study chromosome segregation at three timescales: we first show how automated tracking of kinetochores enables investigation of mitotic spindle and chromosome dynamics in the seconds-to-minutes timescale; next we highlight how new DNA live dyes allow the study of chromosome segregation over a period of several hours in any cell line; finally, we demonstrate how image sequences acquired over several days can reveal the fate of whole cell populations over several consecutive cell divisions.
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Affiliation(s)
- Anna-Maria Olziersky
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Chris A Smith
- Centre for Mechanochemical Cell Biology & Division of Biomedical Science, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Nigel Burroughs
- Mathematics Institute, University of Warwick, Coventry, United Kingdom
| | - Andrew D McAinsh
- Centre for Mechanochemical Cell Biology & Division of Biomedical Science, Warwick Medical School, University of Warwick, Coventry, United Kingdom.
| | - Patrick Meraldi
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland.
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42
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Zhu Y, Tan W, Lee WL. An in vitro Microscopy-based Assay for Microtubule-binding and Microtubule-crosslinking by Budding Yeast Microtubule-associated Protein. Bio Protoc 2018; 8:e3110. [PMID: 30733975 DOI: 10.21769/bioprotoc.3110] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In this protocol, we describe a simple microscopy-based method to assess the interaction of a microtubule-associated protein (MAP) with microtubules. The interaction between MAP and microtubules is typically assessed by a co-sedimentation assay, which measures the amount of MAP that co-pellets with microtubules by centrifugation, followed by SDS-PAGE analysis of the supernatant and pellet fractions. However, MAPs that form large oligomers tend to pellet on their own during the centrifugation step, making it difficult to assess co-sedimentation. Here we describe a microscopy-based assay that measures microtubule binding by direct visualization using fluorescently-labeled MAP, solving the limitations of the co-sedimentation assay. Additionally, we recently reported quantification of microtubule bundling by measuring the thickness of individual microtubule structures observed in the microscopy-based assay, making the protocol more advantageous than the traditional microtubule co-pelleting assay.
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Affiliation(s)
- Yili Zhu
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Weimin Tan
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Wei-Lih Lee
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
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43
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Abstract
As cell size decreases during the reductive divisions of early development, intracellular structures must shrink to fit. In this issue of Developmental Cell, Lacroix et al. (2018) identify a conserved mechanism of spindle scaling in nematode and sea urchin embryos whereby spindle microtubule polymerization rates decrease as development proceeds.
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Dave S, Anderson SJ, Sinha Roy P, Nsamba ET, Bunning AR, Fukuda Y, Gupta ML. Discrete regions of the kinesin-8 Kip3 tail differentially mediate astral microtubule stability and spindle disassembly. Mol Biol Cell 2018; 29:1866-1877. [PMID: 29874146 PMCID: PMC6085823 DOI: 10.1091/mbc.e18-03-0199] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
To function in diverse cellular processes, the dynamic properties of microtubules must be tightly regulated. Cellular microtubules are influenced by a multitude of regulatory proteins, but how their activities are spatiotemporally coordinated within the cell, or on specific microtubules, remains mostly obscure. The conserved kinesin-8 motor proteins are important microtubule regulators, and family members from diverse species combine directed motility with the ability to modify microtubule dynamics. Yet how kinesin-8 activities are appropriately deployed in the cellular context is largely unknown. Here we reveal the importance of the nonmotor tail in differentially controlling the physiological functions of the budding yeast kinesin-8, Kip3. We demonstrate that the tailless Kip3 motor domain adequately governs microtubule dynamics at the bud tip to allow spindle positioning in early mitosis. Notably, discrete regions of the tail mediate specific functions of Kip3 on astral and spindle microtubules. The region proximal to the motor domain operates to spatially regulate astral microtubule stability, while the distal tail serves a previously unrecognized role to control the timing of mitotic spindle disassembly. These findings provide insights into how nonmotor tail domains differentially control kinesin functions in cells and the mechanisms that spatiotemporally control the stability of cellular microtubules.
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Affiliation(s)
- Sandeep Dave
- Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011
| | - Samuel J Anderson
- Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011
| | - Pallavi Sinha Roy
- Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011
| | - Emmanuel T Nsamba
- Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011
| | - Angela R Bunning
- Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011
| | - Yusuke Fukuda
- Cell and Molecular Biology, The University of Chicago, Chicago, IL 60637
| | - Mohan L Gupta
- Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011
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G. Cortés JC, Ramos M, Konomi M, Barragán I, Moreno MB, Alcaide-Gavilán M, Moreno S, Osumi M, Pérez P, Ribas JC. Specific detection of fission yeast primary septum reveals septum and cleavage furrow ingression during early anaphase independent of mitosis completion. PLoS Genet 2018; 14:e1007388. [PMID: 29813053 PMCID: PMC5993333 DOI: 10.1371/journal.pgen.1007388] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 06/08/2018] [Accepted: 05/01/2018] [Indexed: 11/27/2022] Open
Abstract
It is widely accepted in eukaryotes that the cleavage furrow only initiates after mitosis completion. In fission yeast, cytokinesis requires the synthesis of a septum tightly coupled to cleavage furrow ingression. The current cytokinesis model establishes that simultaneous septation and furrow ingression only initiate after spindle breakage and mitosis exit. Thus, this model considers that although Cdk1 is inactivated at early-anaphase, septation onset requires the long elapsed time until mitosis completion and full activation of the Hippo-like SIN pathway. Here, we studied the precise timing of septation onset regarding mitosis by exploiting both the septum-specific detection with the fluorochrome calcofluor and the high-resolution electron microscopy during anaphase and telophase. Contrarily to the existing model, we found that both septum and cleavage furrow start to ingress at early anaphase B, long before spindle breakage, with a slow ingression rate during anaphase B, and greatly increasing after telophase onset. This shows that mitosis and cleavage furrow ingression are not concatenated but simultaneous events in fission yeast. We found that the timing of septation during early anaphase correlates with the cell size and is regulated by the corresponding levels of SIN Etd1 and Rho1. Cdk1 inactivation was directly required for timely septation in early anaphase. Strikingly the reduced SIN activity present after Cdk1 loss was enough to trigger septation by immediately inducing the medial recruitment of the SIN kinase complex Sid2-Mob1. On the other hand, septation onset did not depend on the SIN asymmetry establishment, which is considered a hallmark for SIN activation. These results recalibrate the timing of key cytokinetic events in fission yeast; and unveil a size-dependent control mechanism that synchronizes simultaneous nuclei separation with septum and cleavage furrow ingression to safeguard the proper chromosome segregation during cell division. Fission yeast cytokinesis requires the invagination of the equatorial plasma membrane (cleavage furrow ingression) coupled to the synthesis of a special wall structure named septum (septation). Despite Cdk1 kinase is inactivated in early anaphase, it is believed that cleavage furrow ingression and septation onset require anaphase progression and mitosis completion, only initiating after the complete activation of the Hippo-like septation initiation network (SIN) after telophase onset. Here, we studied the precise timing of septation start with respect to mitosis through specific septum-staining and electron microscopy. We found that septum and cleavage furrow ingression initiate in early anaphase, showing first a slow ingression rate during anaphase B, and increasing to a fast ingression rate after telophase onset. Thus, mitosis and cleavage furrow ingression are not concatenated but simultaneous events in fission yeast. The timing of septation correlated with cell size and depended on the level of cytoplasmic activators like SIN Etd1 and Rho1. We further analyzed the mitotic mechanisms that control the septation onset during early anaphase. Cdk1 directly regulated the timing of septation onset during early anaphase, and the low SIN activity present after Cdk1 inactivation was enough to trigger septation. Globally, these results recalibrate the timing of the main cytokinetic events of fission yeast and reveal a size-dependent control mechanism that synchronizes simultaneous nuclei separation with septum and cleavage furrow ingression.
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Affiliation(s)
- Juan Carlos G. Cortés
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
- * E-mail:
| | - Mariona Ramos
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
| | - Mami Konomi
- Laboratory of Electron Microscopy/Bio-imaging Centre, and Department of Chemical and Biological Sciences, Japan Women's University, Mejirodai, Bunkyo-ku, Tokyo, Japan
| | - Iris Barragán
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
| | - M. Belén Moreno
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
| | - María Alcaide-Gavilán
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide/Consejo Superior de Investigaciones Científicas, Sevilla, Spain
| | - Sergio Moreno
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
| | - Masako Osumi
- Laboratory of Electron Microscopy/Bio-imaging Centre, and Department of Chemical and Biological Sciences, Japan Women's University, Mejirodai, Bunkyo-ku, Tokyo, Japan
- NPO: Integrated Imaging Research Support, Hirakawa-cho, Chiyoda-ku, Tokyo, Japan
| | - Pilar Pérez
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
| | - Juan Carlos Ribas
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
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Larsson VJ, Jafferali MH, Vijayaraghavan B, Figueroa RA, Hallberg E. Mitotic spindle assembly and γ-tubulin localisation depend on the integral nuclear membrane protein Samp1. J Cell Sci 2018. [PMID: 29514856 PMCID: PMC5963844 DOI: 10.1242/jcs.211664] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We have investigated a possible role for the inner nuclear membrane protein Samp1 (also known as TMEM201) in the mitotic machinery. Live-cell imaging showed that Samp1a–YFP (Samp1a is the short isoform of Samp1) distributed as filamentous structures in the mitotic spindle, partially colocalising with β-tubulin. Samp1 depletion resulted in an increased frequency of cells with signs of chromosomal mis-segregation and prolonged metaphase, indicating problems with spindle assembly and/or chromosomal alignment. Consistent with this, mitotic spindles in Samp1-depleted cells contained significantly lower levels of β-tubulin and γ-tubulin, phenotypes that were rescued by overexpression of Samp1a–YFP. We found that Samp1 can bind directly to γ-tubulin and that Samp1 co-precipitated with γ-tubulin and the HAUS6 subunit of the Augmin complex in live cells. The levels of HAUS6, in the mitotic spindle also decreased after Samp1 depletion. We show that Samp1 is involved in the recruitment of HAUS6 and γ-tubulin to the mitotic spindle. Samp1 is the first inner nuclear membrane protein shown to have a function in mitotic spindle assembly. Highlighted Article: The transmembrane inner nuclear membrane protein Samp1 has a functional role in recruitment of γ-tubulin to the mitotic spindle and correct spindle assembly.
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Affiliation(s)
- Veronica J Larsson
- Department of Neurochemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | | | | | - Ricardo A Figueroa
- Department of Neurochemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Einar Hallberg
- Department of Neurochemistry, Stockholm University, SE-106 91 Stockholm, Sweden
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Tolić IM. Mitotic spindle: kinetochore fibers hold on tight to interpolar bundles. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2018; 47:191-203. [PMID: 28725997 PMCID: PMC5845649 DOI: 10.1007/s00249-017-1244-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/30/2017] [Accepted: 07/02/2017] [Indexed: 12/24/2022]
Abstract
When a cell starts to divide, it forms a spindle, a micro-machine made of microtubules, which separates the duplicated chromosomes. The attachment of microtubules to chromosomes is mediated by kinetochores, protein complexes on the chromosome. Spindle microtubules can be divided into three major classes: kinetochore microtubules, which form k-fibers ending at the kinetochore; interpolar microtubules, which extend from the opposite sides of the spindle and interact in the middle; and astral microtubules, which extend towards the cell cortex. Recent work in human cells has shown a close relationship between interpolar and kinetochore microtubules, where interpolar bundles are attached laterally to kinetochore fibers almost all along their length, acting as a bridge between sister k-fibers. Most of the interpolar bundles are attached to a pair of sister kinetochore fibers and vice versa. Thus, the spindle is made of modules consisting of a pair of sister kinetochore fibers and a bundle of interpolar microtubules that connects them. These interpolar bundles, termed bridging fibers, balance the forces acting at kinetochores and support the rounded shape of the spindle during metaphase. This review discusses the structure, function, and formation of kinetochore fibers and interpolar bundles, with an emphasis on how they interact. Their connections have an impact on the force balance in the spindle and on chromosome movement during mitosis because the forces in interpolar bundles are transmitted to kinetochore fibers and hence to kinetochores through these connections.
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Affiliation(s)
- Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000, Zagreb, Croatia.
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48
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Jevtić P, Milunović-Jevtić A, Dilsaver MR, Gatlin JC, Levy DL. Use of Xenopus cell-free extracts to study size regulation of subcellular structures. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2018; 60:277-288. [PMID: 27759156 DOI: 10.1387/ijdb.160158dl] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Striking size variations are prominent throughout biology, at the organismal, cellular, and subcellular levels. Important fundamental questions concern organelle size regulation and how organelle size is regulated relative to cell size, also known as scaling. Uncovering mechanisms of organelle size regulation will inform the functional significance of size as well as the implications of misregulated size, for instance in the case of nuclear enlargement in cancer. Xenopus egg and embryo extracts are powerful cell-free systems that have been utilized extensively for mechanistic and functional studies of various organelles and subcellular structures. The open biochemical nature of the extract permits facile manipulation of its composition, and in recent years extract approaches have illuminated mechanisms of organelle size regulation. This review largely focuses on in vitro Xenopus studies that have identified regulators of nuclear and spindle size. We also discuss potential relationships between size scaling of the nucleus and spindle, size regulation of other subcellular structures, and extract experiments that have clarified developmental timing mechanisms. We conclude by offering some future prospects, notably the integration of Xenopus extract with microfluidic technology.
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Affiliation(s)
- Predrag Jevtić
- Department of Molecular Biology, University of Wyoming, Laramie, WY, USA
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49
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Vázquez-Diez C, FitzHarris G. Causes and consequences of chromosome segregation error in preimplantation embryos. Reproduction 2018; 155:R63-R76. [DOI: 10.1530/rep-17-0569] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 10/19/2017] [Accepted: 11/06/2017] [Indexed: 01/04/2023]
Abstract
Errors in chromosome segregation are common during the mitotic divisions of preimplantation development in mammalian embryos, giving rise to so-called ‘mosaic’ embryos possessing a mixture of euploid and aneuploid cells. Mosaicism is widely considered to be detrimental to embryo quality and is frequently used as criteria to select embryos for transfer in human fertility clinics. However, despite the clear clinical importance, the underlying defects in cell division that result in mosaic aneuploidy remain elusive. In this review, we summarise recent findings from clinical and animal model studies that provide new insights into the fundamental mechanisms of chromosome segregation in the highly unusual cellular environment of early preimplantation development and consider recent clues as to why errors should commonly occur in this setting. We furthermore discuss recent evidence suggesting that mosaicism is not an irrevocable barrier to a healthy pregnancy. Understanding the causes and biological impacts of mosaic aneuploidy will be pivotal in the development and fine-tuning of clinical embryo selection methods.
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50
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Cis-trimethoxy resveratrol induces intrinsic apoptosis via prometaphase arrest and prolonged CDK1 activation pathway in human Jurkat T cells. Oncotarget 2017; 9:4969-4984. [PMID: 29435156 PMCID: PMC5797027 DOI: 10.18632/oncotarget.23576] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 12/05/2017] [Indexed: 12/23/2022] Open
Abstract
Cis-trimethoxy resveratrol (cis-3M-RES) induced dose-dependent cytotoxicity and apoptotic DNA fragmentation in Jurkat T cell clones (JT/Neo); however, it induced only cytostasis in BCL-2-overexpressing cells (JT/BCL-2). Treatment with 0.25 μM cis-3M-RES induced G2/M arrest, BAK activation, Δψm loss, caspase-9 and caspase-3 activation, and poly (ADP-ribose) polymerase (PARP) cleavage in JT/Neo cells time-dependently but did not induce these events, except G2/M arrest, in JT/BCL-2 cells. Moreover, cis-3M-RES induced CDK1 activation, BCL-2 phosphorylation at Ser-70, MCL-1 phosphorylation at Ser-159/Thr-163, and BIM (BIMEL and BIML) phosphorylation irrespective of BCL-2 overexpression. Enforced G1/S arrest by using a G1/S blocker aphidicolin completely inhibited cis-3M-RES-induced apoptotic events. Cis-3M-RES-induced phosphorylation of BCL-2 family proteins and mitochondrial apoptotic events were suppressed by a validated CDK1 inhibitor RO3306. Immunofluorescence microscopy showed that cis-3M-RES induced mitotic spindle defects and prometaphase arrest. The rate of intracellular polymeric tubulin to monomeric tubulin decreased markedly by cis-3M-RES (0.1-1.0 μM). Wild-type Jurkat clone A3, FADD-deficient Jurkat clone I2.1, and caspase-8-deficient Jurkat clone I9.2 exhibited similar susceptibilities to the cytotoxicity of cis-3M-RES, excluding contribution of the extrinsic death receptor-dependent pathway to the apoptosis. IC50 values of cis-3M-RES against Jurkat E6.1, U937, HL-60, and HeLa cells were 0.07-0.17 μM, whereas those against unstimulated human peripheral T cells and phytohaemagglutinin A-stimulated peripheral T cells were >10.0 and 0.23 μM, respectively. These results indicate that the antitumor activity of cis-3M-RES is mediated by microtubule damage, and subsequent prometaphase arrest and prolonged CDK1 activation that cause BAK-mediated mitochondrial apoptosis, and suggest that cis-3M-RES is a promising agent to treat leukemia.
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