1
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Neahring L, Cho NH, He Y, Liu G, Fernandes J, Rux CJ, Nakos K, Subramanian R, Upadhyayula S, Yildiz A, Dumont S. Torques within and outside the human spindle balance twist at anaphase. J Cell Biol 2024; 223:e202312046. [PMID: 38869473 PMCID: PMC11176257 DOI: 10.1083/jcb.202312046] [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: 12/11/2023] [Revised: 05/14/2024] [Accepted: 05/30/2024] [Indexed: 06/14/2024] Open
Abstract
At each cell division, nanometer-scale motors and microtubules give rise to the micron-scale spindle. Many mitotic motors step helically around microtubules in vitro, and most are predicted to twist the spindle in a left-handed direction. However, the human spindle exhibits only slight global twist, raising the question of how these molecular torques are balanced. Here, we find that anaphase spindles in the epithelial cell line MCF10A have a high baseline twist, and we identify factors that both increase and decrease this twist. The midzone motors KIF4A and MKLP1 are together required for left-handed twist at anaphase, and we show that KIF4A generates left-handed torque in vitro. The actin cytoskeleton also contributes to left-handed twist, but dynein and its cortical recruitment factor LGN counteract it. Together, our work demonstrates that force generators regulate twist in opposite directions from both within and outside the spindle, preventing strong spindle twist during chromosome segregation.
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Affiliation(s)
- Lila Neahring
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Developmental and Stem Cell Biology Graduate Program, University of California San Francisco, San Francisco, CA, USA
| | - Nathan H. Cho
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Tetrad Graduate Program, University of California San Francisco, San Francisco, CA, USA
| | - Yifei He
- Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
| | - Gaoxiang Liu
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Jonathan Fernandes
- Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
| | - Caleb J. Rux
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- UC Berkeley/UC San Francisco Graduate Group in Bioengineering, Berkeley, CA, USA
| | - Konstantinos Nakos
- 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
| | - Srigokul Upadhyayula
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Ahmet Yildiz
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
- Physics Department, University of California Berkeley, Berkeley, CA, USA
| | - Sophie Dumont
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Developmental and Stem Cell Biology Graduate Program, University of California San Francisco, San Francisco, CA, USA
- Tetrad Graduate Program, University of California San Francisco, San Francisco, CA, USA
- UC Berkeley/UC San Francisco Graduate Group in Bioengineering, Berkeley, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
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2
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Meißner L, Niese L, Diez S. Helical motion and torque generation by microtubule motors. Curr Opin Cell Biol 2024; 88:102367. [PMID: 38735207 DOI: 10.1016/j.ceb.2024.102367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 05/14/2024]
Abstract
Microtubule motors play key roles in cellular functions, such as transport, mitosis and cell motility. Fueled by ATP hydrolysis, they convert chemical energy into mechanical work, which enables their movement on microtubules. While their motion along the long axis of microtubules has been studied extensively, some motors display an off-axis component, which results in helical motion around microtubules and the generation of torque in addition to linear forces. Understanding these nuanced movements expands our comprehension of motor protein dynamics and their impact on cellular processes.
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Affiliation(s)
- Laura Meißner
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307 Dresden, Germany
| | - Lukas Niese
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307 Dresden, Germany
| | - Stefan Diez
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307 Dresden, Germany; Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany; Cluster of Excellence Physics of Life, TUD Dresden University of Technology, 01062 Dresden, Germany.
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3
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Shah H, Olivetta M, Bhickta C, Ronchi P, Trupinić M, Tromer EC, Tolić IM, Schwab Y, Dudin O, Dey G. Life-cycle-coupled evolution of mitosis in close relatives of animals. Nature 2024; 630:116-122. [PMID: 38778110 PMCID: PMC11153136 DOI: 10.1038/s41586-024-07430-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 04/16/2024] [Indexed: 05/25/2024]
Abstract
Eukaryotes have evolved towards one of two extremes along a spectrum of strategies for remodelling the nuclear envelope during cell division: disassembling the nuclear envelope in an open mitosis or constructing an intranuclear spindle in a closed mitosis1,2. Both classes of mitotic remodelling involve key differences in the core division machinery but the evolutionary reasons for adopting a specific mechanism are unclear. Here we use an integrated comparative genomics and ultrastructural imaging approach to investigate mitotic strategies in Ichthyosporea, close relatives of animals and fungi. We show that species in this clade have diverged towards either a fungal-like closed mitosis or an animal-like open mitosis, probably to support distinct multinucleated or uninucleated states. Our results indicate that multinucleated life cycles favour the evolution of closed mitosis.
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Affiliation(s)
- Hiral Shah
- Cell Biology and Biophysics, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
| | - Marine Olivetta
- Swiss Institute for Experimental Cancer Research, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Chandni Bhickta
- Cell Biology and Biophysics, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Paolo Ronchi
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Monika Trupinić
- Division of Molecular Biology, Ruđer Bošković Institute (RBI), Zagreb, Croatia
| | - Eelco C Tromer
- Cell Biochemistry, Groningen Biomolecular Sciences & Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute (RBI), Zagreb, Croatia
| | - Yannick Schwab
- Cell Biology and Biophysics, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Omaya Dudin
- Swiss Institute for Experimental Cancer Research, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.
| | - Gautam Dey
- Cell Biology and Biophysics, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
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4
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Meißner L, Niese L, Schüring I, Mitra A, Diez S. Human kinesin-5 KIF11 drives the helical motion of anti-parallel and parallel microtubules around each other. EMBO J 2024; 43:1244-1256. [PMID: 38424239 PMCID: PMC10987665 DOI: 10.1038/s44318-024-00048-x] [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: 07/27/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 03/02/2024] Open
Abstract
During mitosis, motor proteins and microtubule-associated protein organize the spindle apparatus by cross-linking and sliding microtubules. Kinesin-5 plays a vital role in spindle formation and maintenance, potentially inducing twist in the spindle fibers. The off-axis power stroke of kinesin-5 could generate this twist, but its implications in microtubule organization remain unclear. Here, we investigate 3D microtubule-microtubule sliding mediated by the human kinesin-5, KIF11, and found that the motor caused right-handed helical motion of anti-parallel microtubules around each other. The sidestepping ratio increased with reduced ATP concentration, indicating that forward and sideways stepping of the motor are not strictly coupled. Further, the microtubule-microtubule distance (motor extension) during sliding decreased with increasing sliding velocity. Intriguingly, parallel microtubules cross-linked by KIF11 orbited without forward motion, with nearly full motor extension. Altering the length of the neck linker increased the forward velocity and pitch of microtubules in anti-parallel overlaps. Taken together, we suggest that helical motion and orbiting of microtubules, driven by KIF11, contributes to flexible and context-dependent filament organization, as well as torque regulation within the mitotic spindle.
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Affiliation(s)
- Laura Meißner
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany
- BASS Center, Molecular Biophysics and Biochemistry Department, Yale University, 06511, New Haven, USA
| | - Lukas Niese
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany
| | - Irene Schüring
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany
| | - Aniruddha Mitra
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584CH, Utrecht, Netherlands
| | - Stefan Diez
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany.
- Max Planck Institute for Molecular Cell Biology and Genetics, 01307, Dresden, Germany.
- Cluster of Excellence Physics of Life, TUD Dresden University of Technology, 01062, Dresden, Germany.
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5
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Maxian O, Mogilner A. Helical motors and formins synergize to compact chiral filopodial bundles: A theoretical perspective. Eur J Cell Biol 2024; 103:151383. [PMID: 38237507 DOI: 10.1016/j.ejcb.2023.151383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 12/19/2023] [Accepted: 12/30/2023] [Indexed: 01/28/2024] Open
Abstract
Chiral actin bundles have been shown to play an important role in cell dynamics, but our understanding of the molecular mechanisms which combine to generate chirality remains incomplete. To address this, we numerically simulate a crosslinked filopodial bundle under the actions of helical myosin motors and/or formins and examine the collective buckling and twisting of the actin bundle. We first show that a number of proposed mechanisms to buckle polymerizing actin bundles without motor activity fail under biologically-realistic parameters. We then demonstrate that a simplified model of myosin spinning action at the bundle base effectively "braids" the bundle, but cannot control compaction at the fiber tips. Finally, we show that formin-mediated polymerization and motor activity can act synergitically to compact filopodium bundles, as motor activity bends filaments into shapes that activate twist forces induced by formins. Stochastic fluctuations of actin polymerization rates and slower cross linking dynamics both increase buckling and decrease compaction. We discuss implications of our findings for mechanisms of cytoskeletal chirality.
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Affiliation(s)
- Ondrej Maxian
- Courant Institute, New York University, New York, NY 10012, USA; Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60615, USA; Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60615, USA
| | - Alex Mogilner
- Courant Institute, New York University, New York, NY 10012, USA; Department of Biology, New York University, New York, NY 10012, USA.
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6
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Neahring L, He Y, Cho NH, Liu G, Fernandes J, Rux CJ, Nakos K, Subramanian R, Upadhyayula S, Yildiz A, Dumont S. Torques within and outside the human spindle balance twist at anaphase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.10.570990. [PMID: 38405786 PMCID: PMC10888964 DOI: 10.1101/2023.12.10.570990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
At each cell division, nanometer-scale motors and microtubules give rise to the micron-scale spindle. Many mitotic motors step helically around microtubules in vitro, and most are predicted to twist the spindle in a left-handed direction. However, the human spindle exhibits only slight global twist, raising the question of how these molecular torques are balanced. Here, using lattice light sheet microscopy, we find that anaphase spindles in the epithelial cell line MCF10A have a high baseline twist, and we identify factors that both increase and decrease this twist. The midzone motors KIF4A and MKLP1 are redundantly required for left-handed twist at anaphase, and we show that KIF4A generates left-handed torque in vitro. The actin cytoskeleton also contributes to left-handed twist, but dynein and its cortical recruitment factor LGN counteract it. Together, our work demonstrates that force generators regulate twist in opposite directions from both within and outside the spindle, preventing strong spindle twist during chromosome segregation.
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Affiliation(s)
- Lila Neahring
- Department of Bioengineering & Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Developmental & Stem Cell Biology Graduate Program, University of California San Francisco, San Francisco, CA, USA
| | - Yifei He
- Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
| | - Nathan H. Cho
- Department of Bioengineering & Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Tetrad Graduate Program, University of California San Francisco, San Francisco, CA, USA
| | - Gaoxiang Liu
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Jonathan Fernandes
- Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
| | - Caleb J. Rux
- Department of Bioengineering & Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- UC Berkeley/UC San Francisco Graduate Group in Bioengineering, Berkeley, CA, USA
| | - Konstantinos Nakos
- 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
| | - Srigokul Upadhyayula
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Ahmet Yildiz
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
- Physics Department, University of California Berkeley, Berkeley, CA, USA
| | - Sophie Dumont
- Department of Bioengineering & Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Developmental & Stem Cell Biology Graduate Program, University of California San Francisco, San Francisco, CA, USA
- Tetrad Graduate Program, University of California San Francisco, San Francisco, CA, USA
- UC Berkeley/UC San Francisco Graduate Group in Bioengineering, Berkeley, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Department of Biochemistry & Biophysics, University of California San Francisco, San Francisco, CA, USA
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7
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Valdez VA, Neahring L, Petry S, Dumont S. Mechanisms underlying spindle assembly and robustness. Nat Rev Mol Cell Biol 2023; 24:523-542. [PMID: 36977834 PMCID: PMC10642710 DOI: 10.1038/s41580-023-00584-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2023] [Indexed: 03/30/2023]
Abstract
The microtubule-based spindle orchestrates chromosome segregation during cell division. Following more than a century of study, many components and pathways contributing to spindle assembly have been described, but how the spindle robustly assembles remains incompletely understood. This process involves the self-organization of a large number of molecular parts - up to hundreds of thousands in vertebrate cells - whose local interactions give rise to a cellular-scale structure with emergent architecture, mechanics and function. In this Review, we discuss key concepts in our understanding of spindle assembly, focusing on recent advances and the new approaches that enabled them. We describe the pathways that generate the microtubule framework of the spindle by driving microtubule nucleation in a spatially controlled fashion and present recent insights regarding the organization of individual microtubules into structural modules. Finally, we discuss the emergent properties of the spindle that enable robust chromosome segregation.
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Affiliation(s)
| | - Lila Neahring
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA, USA
- Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA, USA
| | - Sabine Petry
- Molecular Biology, Princeton University, Princeton, NJ, USA.
| | - Sophie Dumont
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA, USA.
- Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA, USA.
- Department of Biochemistry & Biophysics, UCSF, San Francisco, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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8
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Revignas D, Ferrarini A. Spontaneous Twisting of Achiral Hard Rod Nematics. PHYSICAL REVIEW LETTERS 2023; 130:028102. [PMID: 36706401 DOI: 10.1103/physrevlett.130.028102] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/25/2022] [Accepted: 12/09/2022] [Indexed: 06/18/2023]
Abstract
Since Onsager's seminal work, hard rods have been taken as a prototype of nematic liquid crystals, characterized by uniaxial order and a uniform director field as a ground state. Here, using Onsager theory to calculate the free energy in the presence of arbitrary deformations, we find that hard rod nematics have an intrinsic tendency to twist around their ordering axis (double twist), driven by a mechanism in which the orientational fluctuations of particles play a key role. The anisotropic hard core potential used here is arguably the simplest form of interaction able to originate spontaneous breaking of mirror symmetry in a 3D fluid. Our results are discussed in relation to the recent discovery of a double twisted ground state in cylindrically confined lyotropic chromonic liquid crystals.
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Affiliation(s)
- Davide Revignas
- Department of Chemical Sciences, University of Padova Via Marzolo 1, 35131 Padova, Italy
| | - Alberta Ferrarini
- Department of Chemical Sciences, University of Padova Via Marzolo 1, 35131 Padova, Italy
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9
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Hiraiwa T, Akiyama R, Inoue D, Kabir AMR, Kakugo A. Collision-induced torque mediates the transition of chiral dynamic patterns formed by active particles. Phys Chem Chem Phys 2022; 24:28782-28787. [PMID: 36382471 DOI: 10.1039/d2cp03879j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Controlling the patterns formed by self-propelled particles through dynamic self-organization is a challenging task. Although varieties of patterns associated with chiral self-propelled particles have been reported, essential factors that determine the morphology of the patterns have remained unclear. Here, we explore theoretically how torque formed upon collision of the particles affects the dynamic self-organization of the particles and determine the patterns. Based on a particle-based model with collision-induced torque and torque associated with self-propulsion, we find that introducing collision-induced torque turns the homogeneous bi-directionally aligned particles into rotating mono-polar flocks, which helps resolve a discrepancy in the earlier observations in microfilament gliding assays.
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Affiliation(s)
- Tetsuya Hiraiwa
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore. .,Universal Biology Institute, The University of Tokyo, Hongo, Tokyo 113-0033, Japan
| | - Ryo Akiyama
- Department of Chemistry, Kyushu University, Fukuoka 819-0395, Japan
| | - Daisuke Inoue
- Faculty of Design, Kyushu University, Fukuoka 815-8540, Japan
| | | | - Akira Kakugo
- Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
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10
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Suresh P, Galstyan V, Phillips R, Dumont S. Modeling and mechanical perturbations reveal how spatially regulated anchorage gives rise to spatially distinct mechanics across the mammalian spindle. eLife 2022; 11:e79558. [PMID: 36346735 PMCID: PMC9642996 DOI: 10.7554/elife.79558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 10/12/2022] [Indexed: 11/09/2022] Open
Abstract
During cell division, the spindle generates force to move chromosomes. In mammals, microtubule bundles called kinetochore-fibers (k-fibers) attach to and segregate chromosomes. To do so, k-fibers must be robustly anchored to the dynamic spindle. We previously developed microneedle manipulation to mechanically challenge k-fiber anchorage, and observed spatially distinct response features revealing the presence of heterogeneous anchorage (Suresh et al., 2020). How anchorage is precisely spatially regulated, and what forces are necessary and sufficient to recapitulate the k-fiber's response to force remain unclear. Here, we develop a coarse-grained k-fiber model and combine with manipulation experiments to infer underlying anchorage using shape analysis. By systematically testing different anchorage schemes, we find that forces solely at k-fiber ends are sufficient to recapitulate unmanipulated k-fiber shapes, but not manipulated ones for which lateral anchorage over a 3 μm length scale near chromosomes is also essential. Such anchorage robustly preserves k-fiber orientation near chromosomes while allowing pivoting around poles. Anchorage over a shorter length scale cannot robustly restrict pivoting near chromosomes, while anchorage throughout the spindle obstructs pivoting at poles. Together, this work reveals how spatially regulated anchorage gives rise to spatially distinct mechanics in the mammalian spindle, which we propose are key for function.
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Affiliation(s)
- Pooja Suresh
- Biophysics Graduate Program, University of California, San FranciscoSan FranciscoUnited States
- Department of Bioengineering and Therapeutic Sciences, University of California, San FranciscoSan FranciscoUnited States
| | - Vahe Galstyan
- Biochemistry and Molecular Biophysics Option, California Institute of TechnologyPasadenaUnited States
- A. Alikhanyan National Laboratory (Yerevan Physics Institute)YerevanArmenia
| | - Rob Phillips
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
- Department of Physics, California Institute of TechnologyPasadenaUnited States
- Chan Zuckerberg Biohub, San FranciscoSan FranciscoUnited States
| | - Sophie Dumont
- Biophysics Graduate Program, University of California, San FranciscoSan FranciscoUnited States
- Department of Bioengineering and Therapeutic Sciences, University of California, San FranciscoSan FranciscoUnited States
- Chan Zuckerberg Biohub, San FranciscoSan FranciscoUnited States
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
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11
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Štimac V, Koprivec I, Manenica M, Simunić J, Tolić IM. Augmin prevents merotelic attachments by promoting proper arrangement of bridging and kinetochore fibers. eLife 2022; 11:83287. [PMID: 36269126 PMCID: PMC9640188 DOI: 10.7554/elife.83287] [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] [Received: 09/07/2022] [Accepted: 09/26/2022] [Indexed: 11/18/2022] Open
Abstract
The human mitotic spindle is made of microtubules nucleated at centrosomes, at kinetochores, and from pre-existing microtubules by the augmin complex. However, it is unknown how the augmin-mediated nucleation affects distinct microtubule classes and thereby mitotic fidelity. Here, we use superresolution microscopy to analyze the previously indistinguishable microtubule arrangements within the crowded metaphase plate area and demonstrate that augmin is vital for the formation of uniformly arranged parallel units consisting of sister kinetochore fibers connected by a bridging fiber. This ordered geometry helps both prevent and resolve merotelic attachments. Whereas augmin-nucleated bridging fibers prevent merotelic attachments by creating a nearly parallel and highly bundled microtubule arrangement unfavorable for creating additional attachments, augmin-nucleated k-fibers produce robust force required to resolve errors during anaphase. STED microscopy revealed that bridging fibers were impaired twice as much as k-fibers following augmin depletion. The complete absence of bridging fibers from a significant portion of kinetochore pairs, especially in the inner part of the spindle, resulted in the specific reduction of the interkinetochore distance. Taken together, we propose a model where augmin promotes mitotic fidelity by generating assemblies consisting of bridging and kinetochore fibers that align sister kinetochores to face opposite poles, thereby preventing erroneous attachments.
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Affiliation(s)
- Valentina Štimac
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Isabella Koprivec
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Martina Manenica
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Juraj Simunić
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
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12
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Keogh RR, Chandragiri S, Loewe B, Ala-Nissila T, Thampi SP, Shendruk TN. Helical flow states in active nematics. Phys Rev E 2022; 106:L012602. [PMID: 35974522 DOI: 10.1103/physreve.106.l012602] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 06/09/2022] [Indexed: 06/15/2023]
Abstract
We show that confining extensile nematics in three-dimensional (3D) channels leads to the emergence of two self-organized flow states with nonzero helicity. The first is a pair of braided antiparallel streams-this double helix occurs when the activity is moderate, anchoring negligible, and reduced temperature high. The second consists of axially aligned counter-rotating vortices-this grinder train arises between spontaneous axial streaming and the vortex lattice. These two unanticipated helical flow states illustrate the potential of active fluids to break symmetries and form complex but organized spatiotemporal structures in 3D fluidic devices.
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Affiliation(s)
- Ryan R Keogh
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - Santhan Chandragiri
- Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - Benjamin Loewe
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - Tapio Ala-Nissila
- MSP Group, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 11000, FI-00076 Aalto, Espoo, Finland
- Interdisciplinary Centre for Mathematical Modelling, Department of Mathematical Sciences, Loughborough University, Loughborough LE11 3TU, United Kingdom
| | - Sumesh P Thampi
- Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - Tyler N Shendruk
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
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13
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The chirality of the mitotic spindle provides a mechanical response to forces and depends on microtubule motors and augmin. Curr Biol 2022; 32:2480-2493.e6. [PMID: 35537456 PMCID: PMC9235856 DOI: 10.1016/j.cub.2022.04.035] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 02/17/2022] [Accepted: 04/13/2022] [Indexed: 12/24/2022]
Abstract
Forces produced by motor proteins and microtubule dynamics within the mitotic spindle are crucial for proper chromosome segregation. In addition to linear forces, rotational forces or torques are present in the spindle, which are reflected in the left-handed twisted shapes of microtubule bundles that make the spindle chiral. However, the biological role and molecular origins of spindle chirality are unknown. By developing methods for measuring the spindle twist, we show that spindles are most chiral near the metaphase-to-anaphase transition. To assess the role of chirality in spindle mechanics, we compressed the spindles along their axis. This resulted in a stronger left-handed twist, suggesting that the twisted shape allows for a mechanical response to forces. Inhibition or depletion of motor proteins that perform chiral stepping, Eg5/kinesin-5, Kif18A/kinesin-8, MKLP1/kinesin-6, and dynein, decreased the left-handed twist or led to right-handed twist, implying that these motors regulate the twist by rotating microtubules within their antiparallel overlaps or at the spindle pole. A right-handed twist was also observed after the depletion of the microtubule nucleator augmin, indicating its contribution to the twist through the nucleation of antiparallel bridging microtubules. The uncovered switch from left-handed to right-handed twist reveals the existence of competing mechanisms that promote twisting in opposite directions. As round spindles are more twisted than the elongated ones are, we infer that bending and twisting moments are generated by similar molecular mechanisms and propose a physiological role for spindle chirality in allowing the spindle to absorb mechanical load. Video abstract
Spindle twist depends on torque-generating motors Eg5, Kif18A, MKLP1, and dynein Without the microtubule nucleator augmin, spindles show right-handed twist Compression of the spindle along the axis increases the left-handed twist Rounder spindles are more twisted than elongated ones are
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14
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She ZY, Zhong N, Wei YL. Kinesin-5 Eg5 mediates centrosome separation to control spindle assembly in spermatocytes. Chromosoma 2022; 131:87-105. [PMID: 35437661 DOI: 10.1007/s00412-022-00772-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/12/2022] [Accepted: 04/08/2022] [Indexed: 11/25/2022]
Abstract
Timely and accurate centrosome separation is critical for bipolar spindle organization and faithful chromosome segregation during cell division. Kinesin-5 Eg5 is essential for centrosome separation and spindle organization in somatic cells; however, the detailed functions and mechanisms of Eg5 in spermatocytes remain unclear. In this study, we show that Eg5 proteins are located at spindle microtubules and centrosomes in spermatocytes both in vivo and in vitro. We reveal that the spermatocytes are arrested at metaphase I in seminiferous tubules after Eg5 inhibition. Eg5 ablation results in cell cycle arrest, the formation of monopolar spindle, and chromosome misalignment in cultured GC-2 spd cells. Importantly, we find that the long-term inhibition of Eg5 results in an increased number of centrosomes and chromosomal instability in spermatocytes. Our findings indicate that Eg5 mediates centrosome separation to control spindle assembly and chromosome alignment in spermatocytes, which finally contribute to chromosome stability and faithful cell division of the spermatocytes.
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Affiliation(s)
- Zhen-Yu She
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122, Fujian, China.
- Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, Fuzhou, 350122, Fujian, China.
| | - Ning Zhong
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122, Fujian, China
- Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, Fuzhou, 350122, Fujian, China
| | - Ya-Lan Wei
- Fujian Obstetrics and Gynecology Hospital, Fuzhou, 350011, Fujian, China
- Medical Research Center, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001, Fujian, China
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15
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Sinclair AN, de Graffenried CL. Cell division: Naegleria bundles up for mitosis. Curr Biol 2022; 32:R269-R271. [PMID: 35349811 DOI: 10.1016/j.cub.2022.01.079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
How well do we understand the range of mechanisms used by eukaryotes for mitosis? A new study in a highly divergent eukaryote shows that unusual tubulin isoforms can create a mitotic spindle exclusively out of microtubule bundles.
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Affiliation(s)
- Amy N Sinclair
- Abveris, 480 Neponset Street Suite 10B, Canton, MA 02021, USA
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16
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Velle KB, Kennard AS, Trupinić M, Ivec A, Swafford AJM, Nolton E, Rice LM, Tolić IM, Fritz-Laylin LK, Wadsworth P. Naegleria’s mitotic spindles are built from unique tubulins and highlight core spindle features. Curr Biol 2022; 32:1247-1261.e6. [PMID: 35139359 PMCID: PMC9036621 DOI: 10.1016/j.cub.2022.01.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 11/02/2021] [Accepted: 01/12/2022] [Indexed: 12/30/2022]
Abstract
Naegleria gruberi is a unicellular eukaryote whose evolutionary distance from animals and fungi has made it useful for developing hypotheses about the last common eukaryotic ancestor. Naegleria amoebae lack a cytoplasmic microtubule cytoskeleton and assemble microtubules only during mitosis and thus represent a unique system for studying the evolution and functional specificity of mitotic tubulins and the spindles they assemble. Previous studies show that Naegleria amoebae express a divergent α-tubulin during mitosis, and we now show that Naegleria amoebae express a second mitotic α- and two mitotic β-tubulins. The mitotic tubulins are evolutionarily divergent relative to typical α- and β-tubulins and contain residues that suggest distinct microtubule properties. These distinct residues are conserved in mitotic tubulin homologs of the “brain-eating amoeba” Naegleria fowleri, making them potential drug targets. Using quantitative light microscopy, we find that Naegleria’s mitotic spindle is a distinctive barrel-like structure built from a ring of microtubule bundles. Similar to those of other species, Naegleria’s spindle is twisted, and its length increases during mitosis, suggesting that these aspects of mitosis are ancestral features. Because bundle numbers change during metaphase, we hypothesize that the initial bundles represent kinetochore fibers and secondary bundles function as bridging fibers. Naegleria amoebae are profoundly different from other eukaryotes as they lack interphase microtubules. During cell division, Velle et al. show that Naegleria express α- and β-tubulins that are highly divergent at key structural positions. These tubulins form spindles with an unusual architecture: a ring of twisted microtubule bundles.
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Affiliation(s)
- Katrina B Velle
- Department of Biology, University of Massachusetts, 611 N. Pleasant Street, Amherst, MA 01003, USA
| | - Andrew S Kennard
- Department of Biology, University of Massachusetts, 611 N. Pleasant Street, Amherst, MA 01003, USA
| | - Monika Trupinić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Arian Ivec
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia
| | - Andrew J M Swafford
- Department of Biology, University of Massachusetts, 611 N. Pleasant Street, Amherst, MA 01003, USA
| | - Emily Nolton
- Department of Biology, University of Massachusetts, 611 N. Pleasant Street, Amherst, MA 01003, USA
| | - Luke M Rice
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Lillian K Fritz-Laylin
- Department of Biology, University of Massachusetts, 611 N. Pleasant Street, Amherst, MA 01003, USA.
| | - Patricia Wadsworth
- Department of Biology, University of Massachusetts, 611 N. Pleasant Street, Amherst, MA 01003, USA.
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17
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Zhovmer AS, Manning A, Smith C, Hayes JB, Burnette DT, Wang J, Cartagena-Rivera AX, Dokholyan NV, Singh RK, Tabdanov ED. Mechanical Counterbalance of Kinesin and Dynein Motors in a Microtubular Network Regulates Cell Mechanics, 3D Architecture, and Mechanosensing. ACS NANO 2021; 15:17528-17548. [PMID: 34677937 PMCID: PMC9291236 DOI: 10.1021/acsnano.1c04435] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Microtubules (MTs) and MT motor proteins form active 3D networks made of unstretchable cables with rod-like bending mechanics that provide cells with a dynamically changing structural scaffold. In this study, we report an antagonistic mechanical balance within the dynein-kinesin microtubular motor system. Dynein activity drives the microtubular network inward compaction, while isolated activity of kinesins bundles and expands MTs into giant circular bands that deform the cell cortex into discoids. Furthermore, we show that dyneins recruit MTs to sites of cell adhesion, increasing the topographic contact guidance of cells, while kinesins antagonize it via retraction of MTs from sites of cell adhesion. Actin-to-microtubule translocation of septin-9 enhances kinesin-MT interactions, outbalances the activity of kinesins over that of dyneins, and induces the discoid architecture of cells. These orthogonal mechanisms of MT network reorganization highlight the existence of an intricate mechanical balance between motor activities of kinesins and dyneins that controls cell 3D architecture, mechanics, and cell-microenvironment interactions.
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Affiliation(s)
- Alexander S. Zhovmer
- Center
for Biologics Evaluation and Research, U.S.
Food and Drug Administration, Silver Spring, Maryland 20903, United States
- . Tel: 1-301-402-1606
| | - Alexis Manning
- Center
for Biologics Evaluation and Research, U.S.
Food and Drug Administration, Silver Spring, Maryland 20903, United States
| | - Chynna Smith
- Section
on Mechanobiology, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - James B. Hayes
- Department
of Cell and Developmental Biology, Vanderbilt Medical Center, University of Vanderbilt, Nashville, Tennessee 37232, United States
| | - Dylan T. Burnette
- Department
of Cell and Developmental Biology, Vanderbilt Medical Center, University of Vanderbilt, Nashville, Tennessee 37232, United States
| | - Jian Wang
- Department
of Pharmacology, Penn State College of Medicine, Pennsylvania State University, Hummelstown, Pennsylvania 17036, United States
| | - Alexander X. Cartagena-Rivera
- Section
on Mechanobiology, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland 20892, United States
- . Tel: 1-301-503-4033
| | - Nikolay V. Dokholyan
- Department
of Pharmacology, Penn State College of Medicine, Pennsylvania State University, Hummelstown, Pennsylvania 17036, United States
- Department
of Biochemistry & Molecular Biology, Penn State College of Medicine, Pennsylvania State University, Hershey, Pennsylvania 17033, United States
- . Tel: 1-717-531-5177
| | - Rakesh K. Singh
- Department
of Obstetrics and Gynecology, University
of Rochester Medical Center, Rochester, New York 14620, United States
- . Tel: 1-585-276-6281
| | - Erdem D. Tabdanov
- Department
of Pharmacology, Penn State College of Medicine, Pennsylvania State University, Hummelstown, Pennsylvania 17036, United States
- . Tel: 1-717-531-0003 Ext: 4430
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18
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Neahring L, Cho NH, Dumont S. Opposing motors provide mechanical and functional robustness in the human spindle. Dev Cell 2021; 56:3006-3018.e5. [PMID: 34614397 DOI: 10.1016/j.devcel.2021.09.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 07/27/2021] [Accepted: 09/13/2021] [Indexed: 11/30/2022]
Abstract
At each cell division, the spindle self-organizes from microtubules and motors. In human spindles, the motors dynein and Eg5 generate contractile and extensile stress, respectively. Inhibiting dynein or its targeting factor NuMA leads to unfocused, turbulent spindles, and inhibiting Eg5 leads to monopoles; yet, bipolar spindles form when both are inhibited together. What, then, are the roles of these opposing motors? Here, we generate NuMA/dynein- and Eg5-doubly inhibited spindles that not only attain a typical metaphase shape and size but also undergo anaphase. However, these spindles have reduced microtubule dynamics and are mechanically fragile, fracturing under force. Furthermore, they exhibit lagging chromosomes and a dramatic left-handed twist at anaphase. Thus, although these opposing motors are not required for spindle shape, they are essential to its mechanical and functional robustness. This work suggests a design principle whereby opposing active stresses provide robustness to force-generating cellular structures.
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Affiliation(s)
- Lila Neahring
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA 94158, USA; Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA 94143, USA.
| | - Nathan H Cho
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA 94158, USA; Tetrad Graduate Program, UCSF, San Francisco, CA 94158, USA
| | - Sophie Dumont
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA 94158, USA; Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA 94143, USA; Tetrad Graduate Program, UCSF, San Francisco, CA 94158, USA; Department of Biochemistry & Biophysics, UCSF, San Francisco, CA 94158, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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19
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Ivec A, Trupinić M, Tolić IM, Pavin N. Oblique circle method for measuring the curvature and twist of mitotic spindle microtubule bundles. Biophys J 2021; 120:3641-3648. [PMID: 34339637 PMCID: PMC8456293 DOI: 10.1016/j.bpj.2021.07.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 07/03/2021] [Accepted: 07/27/2021] [Indexed: 11/20/2022] Open
Abstract
The highly ordered spatial organization of microtubule bundles in the mitotic spindle is crucial for its proper functioning. The recent discovery of twisted shapes of microtubule bundles and spindle chirality suggests that the bundles extend along curved paths in three dimensions, rather than being confined to a plane. This, in turn, implies that rotational forces, i.e., torques, exist in the spindle in addition to the widely studied linear forces. However, studies of spindle architecture and forces are impeded by a lack of a robust method for the geometric quantification of microtubule bundles in the spindle. In this work, we describe a simple method for measuring and evaluating the shapes of microtubule bundles by characterizing them in terms of their curvature and twist. By using confocal microscopy, we obtain three-dimensional images of spindles, which allows us to trace the entire microtubule bundle. For each traced bundle, we first fit a plane and then fit a circle lying in that plane. With this robust method, we extract the curvature and twist, which represent the geometric information characteristic for each bundle. As the bundle shapes reflect the forces within them, this method is valuable for the understanding of forces that act on chromosomes during mitosis.
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Affiliation(s)
- Arian Ivec
- Department of Physics, Faculty of Science, University of Zagreb, Zagreb, Croatia.
| | - Monika Trupinić
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Nenad Pavin
- Department of Physics, Faculty of Science, University of Zagreb, Zagreb, Croatia.
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20
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Ierushalmi N, Keren K. Cytoskeletal symmetry breaking in animal cells. Curr Opin Cell Biol 2021; 72:91-99. [PMID: 34375786 DOI: 10.1016/j.ceb.2021.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/13/2021] [Accepted: 07/07/2021] [Indexed: 10/20/2022]
Abstract
Symmetry breaking is a crucial step in structure formation and function of all cells, necessary for cell movement, cell division, and polarity establishment. Although the mechanisms of symmetry breaking are diverse, they often share common characteristics. Here we review examples of nematic, polar, and chiral cytoskeletal symmetry breaking in animal cells, and analogous processes in simplified reconstituted systems. We discuss the origins of symmetry breaking, which can arise spontaneously, or involve amplification of a pre-existing external or internal bias to the whole cell level. The underlying mechanisms often involve both chemical and mechanical processes that cooperate to break symmetry in a robust manner, and typically depend on the shape, size, or properties of the cell's boundary.
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Affiliation(s)
- Niv Ierushalmi
- Department of Physics, Technion - Israel Institute of Technology, Haifa, Israel
| | - Kinneret Keren
- Department of Physics, Technion - Israel Institute of Technology, Haifa, Israel; Network Biology Research Laboratories and Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa, Israel.
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21
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Rasamizafy SF, Delsert C, Rabeharivelo G, Cau J, Morin N, van Dijk J. Mitotic Acetylation of Microtubules Promotes Centrosomal PLK1 Recruitment and Is Required to Maintain Bipolar Spindle Homeostasis. Cells 2021; 10:1859. [PMID: 34440628 PMCID: PMC8394630 DOI: 10.3390/cells10081859] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 07/18/2021] [Accepted: 07/19/2021] [Indexed: 12/13/2022] Open
Abstract
Tubulin post-translational modifications regulate microtubule properties and functions. Mitotic spindle microtubules are highly modified. While tubulin detyrosination promotes proper mitotic progression by recruiting specific microtubule-associated proteins motors, tubulin acetylation that occurs on specific microtubule subsets during mitosis is less well understood. Here, we show that siRNA-mediated depletion of the tubulin acetyltransferase ATAT1 in epithelial cells leads to a prolonged prometaphase arrest and the formation of monopolar spindles. This results from collapse of bipolar spindles, as previously described in cells deficient for the mitotic kinase PLK1. ATAT1-depleted mitotic cells have defective recruitment of PLK1 to centrosomes, defects in centrosome maturation and thus microtubule nucleation, as well as labile microtubule-kinetochore attachments. Spindle bipolarity could be restored, in the absence of ATAT1, by stabilizing microtubule plus-ends or by increasing PLK1 activity at centrosomes, demonstrating that the phenotype is not just a consequence of lack of K-fiber stability. We propose that microtubule acetylation of K-fibers is required for a recently evidenced cross talk between centrosomes and kinetochores.
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Affiliation(s)
- Sylvia Fenosoa Rasamizafy
- Université de Montpellier, 34293 Montpellier, France; (S.F.R.); (C.D.); (G.R.); (J.C.)
- Centre National de la Recherche Scientifique (CNRS) UMR5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Claude Delsert
- Université de Montpellier, 34293 Montpellier, France; (S.F.R.); (C.D.); (G.R.); (J.C.)
- Centre National de la Recherche Scientifique (CNRS) UMR5237, 1919 Route de Mende, 34293 Montpellier, France
- Institut Français de Recherche pour l’Exploitation de la mer, L3AS, 34250 Palavas-les-Flots, France
| | - Gabriel Rabeharivelo
- Université de Montpellier, 34293 Montpellier, France; (S.F.R.); (C.D.); (G.R.); (J.C.)
- Centre National de la Recherche Scientifique (CNRS) UMR5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Julien Cau
- Université de Montpellier, 34293 Montpellier, France; (S.F.R.); (C.D.); (G.R.); (J.C.)
- IGH, CNRS UMR 9002, 141, rue de la Cardonille, 34396 Montpellier, France
- Montpellier Rio Imaging, 34293 Montpellier, France
| | - Nathalie Morin
- Université de Montpellier, 34293 Montpellier, France; (S.F.R.); (C.D.); (G.R.); (J.C.)
- Centre National de la Recherche Scientifique (CNRS) UMR5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Juliette van Dijk
- Université de Montpellier, 34293 Montpellier, France; (S.F.R.); (C.D.); (G.R.); (J.C.)
- Centre National de la Recherche Scientifique (CNRS) UMR5237, 1919 Route de Mende, 34293 Montpellier, France
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22
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Sahu S, Herbst L, Quinn R, Ross JL. Crowder and surface effects on self-organization of microtubules. Phys Rev E 2021; 103:062408. [PMID: 34271669 DOI: 10.1103/physreve.103.062408] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 05/14/2021] [Indexed: 12/30/2022]
Abstract
Microtubules are an essential physical building block of cellular systems. They are organized using specific crosslinkers, motors, and influencers of nucleation and growth. With the addition of antiparallel crosslinkers, microtubule self-organization patterns go through a transition from fanlike structures to homogeneous tactoid condensates in vitro. Tactoids are reminiscent of biological mitotic spindles, the cell division machinery. To create these organizations, we previously used polymer crowding agents. Here we study how altering the properties of the crowders, such as type, size, and molecular weight, affects microtubule organization. Comparing simulations with experiments, we observe a scaling law associated with the fanlike patterns in the absence of crosslinkers. Tactoids formed in the presence of crosslinkers show variable length, depending on the crowders. We correlate the subtle differences to filament contour length changes, affected by nucleation and growth rate changes induced by the polymers in solution. Using quantitative image analysis, we deduce that the tactoids differ from traditional liquid crystal organization, as they are limited in width irrespective of crowders and surfaces, and behave as solidlike condensates.
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Affiliation(s)
- Sumon Sahu
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - Lena Herbst
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts 01003, USA
| | - Ryan Quinn
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, Massachusetts 01003, USA
| | - Jennifer L Ross
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
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23
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Afroze F, Inoue D, Farhana TI, Hiraiwa T, Akiyama R, Kabir AMR, Sada K, Kakugo A. Monopolar flocking of microtubules in collective motion. Biochem Biophys Res Commun 2021; 563:73-78. [PMID: 34062389 DOI: 10.1016/j.bbrc.2021.05.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 05/12/2021] [Indexed: 11/16/2022]
Abstract
Flocking is a fascinating coordinated behavior of living organisms or self-propelled particles (SPPs). Particularly, monopolar flocking has been attractive due to its potential applications in various fields. However, the underlying mechanism behind flocking and emergence of monopolar motion in flocking of SPPs has remained obscured. Here, we demonstrate monopolar flocking of kinesin-driven microtubules, a self-propelled biomolecular motor system. Microtubules with an intrinsic structural chirality preferentially move towards counter-clockwise direction. At high density, the CCW motion of microtubules facilitates monopolar flocking and formation of a spiral pattern. The monopolar flocking of microtubules is accounted for by a torque generated when the motion of microtubules was obstructed due to collisions. Our results shed light on flocking and emergence of monopolar motion in flocking of chiral active matters. This work will help regulate the polarity in collective motion of SPPs which in turn will widen their applications in nanotechnology, materials science and engineering.
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Affiliation(s)
- Farhana Afroze
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-0810, Hokkaido, Japan
| | - Daisuke Inoue
- Faculty of Design, Kyushu University, Fukuoka, 815-8540, Japan
| | - Tamanna Ishrat Farhana
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-0810, Hokkaido, Japan
| | - Tetsuya Hiraiwa
- Mechanobiology Institute, National University of Singapore, Singapore, 117411, Singapore; Universal Biology Institute, The University of Tokyo, Hongo, Tokyo, 113-0033, Japan
| | - Ryo Akiyama
- Department of Chemistry, Kyushu University, Fukuoka, 819-0395, Japan
| | | | - Kazuki Sada
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-0810, Hokkaido, Japan; Faculty of Science, Hokkaido University, Sapporo, 060-0810, Hokkaido, Japan
| | - Akira Kakugo
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-0810, Hokkaido, Japan; Faculty of Science, Hokkaido University, Sapporo, 060-0810, Hokkaido, Japan.
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24
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Shi Q, Meng Z, Tian XX, Wang YF, Wang WH. Identification and validation of a hub gene prognostic index for hepatocellular carcinoma. Future Oncol 2021; 17:2193-2208. [PMID: 33620260 DOI: 10.2217/fon-2020-1112] [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] [Indexed: 12/14/2022] Open
Abstract
Aims: We aim to provide new insights into the mechanisms of hepatocellular carcinoma (HCC) and identify key genes as biomarkers for the prognosis of HCC. Materials & methods: Differentially expressed genes between HCC tissues and normal tissues were identified via the Gene Expression Omnibus tool. The top ten hub genes screened by the degree of the protein nodes in the protein-protein interaction network also showed significant associations with overall survival in HCC patients. Results: A prognostic model containing a five-gene signature was constructed to predict the prognosis of HCC via multivariate Cox regression analysis. Conclusion: This study identified a novel five-gene signature (CDK1, CCNB1, CCNB2, BUB1 and KIF11) as a significant independent prognostic factor.
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Affiliation(s)
- Q Shi
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, 450052, China
| | - Z Meng
- The People's Hospital of Henan Province, Zhengzhou, Henan, 450003, China
| | - X X Tian
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, 450052, China
| | - Y F Wang
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, 450052, China
| | - W H Wang
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, 450052, China
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25
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Maruyama Y, Sugawa M, Yamaguchi S, Davies T, Osaki T, Kobayashi T, Yamagishi M, Takeuchi S, Mishima M, Yajima J. CYK4 relaxes the bias in the off-axis motion by MKLP1 kinesin-6. Commun Biol 2021; 4:180. [PMID: 33568771 PMCID: PMC7876049 DOI: 10.1038/s42003-021-01704-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 01/14/2021] [Indexed: 12/18/2022] Open
Abstract
Centralspindlin, a complex of the MKLP1 kinesin-6 and CYK4 GAP subunits, plays key roles in metazoan cytokinesis. CYK4-binding to the long neck region of MKLP1 restricts the configuration of the two MKLP1 motor domains in the centralspindlin. However, it is unclear how the CYK4-binding modulates the interaction of MKLP1 with a microtubule. Here, we performed three-dimensional nanometry of a microbead coated with multiple MKLP1 molecules on a freely suspended microtubule. We found that beads driven by dimeric MKLP1 exhibited persistently left-handed helical trajectories around the microtubule axis, indicating torque generation. By contrast, centralspindlin, like monomeric MKLP1, showed similarly left-handed but less persistent helical movement with occasional rightward movements. Analysis of the fluctuating helical movement indicated that the MKLP1 stochastically makes off-axis motions biased towards the protofilament on the left. CYK4-binding to the neck domains in MKLP1 enables more flexible off-axis motion of centralspindlin, which would help to avoid obstacles along crowded spindle microtubules. Analysing the 3D movement of MKLP1 motors, Maruyama et al. find that dimeric C. elegans MKLP1 drives a left-handed helical motion around the microtubule with minimum protofilament switching to the right side whereas less persistent motions are driven by monomers or by heterotetramers with CYK4. These findings suggest how obstacles along crowded spindle microtubules may be avoided by CYK4 binding to MKLP1.
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Affiliation(s)
- Yohei Maruyama
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Mitsuhiro Sugawa
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan.,Komaba Institute for Science, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Shin Yamaguchi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Tim Davies
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK.,Department of Biosciences, Durham University, Durham, UK
| | - Toshihisa Osaki
- Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Takuya Kobayashi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Masahiko Yamagishi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan.,Komaba Institute for Science, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Shoji Takeuchi
- Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo, Japan.,Research Center for complex Systems Biology, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Masanori Mishima
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK.
| | - Junichiro Yajima
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan. .,Komaba Institute for Science, The University of Tokyo, Meguro-ku, Tokyo, Japan. .,Research Center for complex Systems Biology, The University of Tokyo, Meguro-ku, Tokyo, Japan.
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26
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Tolic´ IM, Pavin N. Mitotic spindle: lessons from theoretical modeling. Mol Biol Cell 2021; 32:218-222. [PMID: 33507108 PMCID: PMC8098832 DOI: 10.1091/mbc.e20-05-0335] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 11/23/2020] [Accepted: 11/24/2020] [Indexed: 11/16/2022] Open
Abstract
Cell biology is immensely complex. To understand how cells work, we try to find patterns and suggest hypotheses to identify underlying mechanisms. However, it is not always easy to create a coherent picture from a huge amount of experimental data on biological systems, where the main players have multiple interactions or act in redundant pathways. In such situations, when a hypothesis does not lead to a conclusion in a direct way, theoretical modeling is a powerful tool because it allows us to formulate hypotheses in a quantitative manner and understand their consequences. A successful model should not only reproduce the basic features of the system but also provide exciting predictions, motivating new experiments. Much is learned when a model based on generally accepted knowledge cannot explain experiments of interest, as this indicates that the original hypothesis needs to be revised. In this Perspective, we discuss these points using our experiences in combining experiments with theory in the field of mitotic spindle mechanics.
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Affiliation(s)
- Iva M. Tolic´
- Division of Molecular Biology, Rud¯er Boškovic´ Institute, 10000 Zagreb, Croatia
| | - Nenad Pavin
- Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
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27
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Pavin N, Tolić IM. Mechanobiology of the Mitotic Spindle. Dev Cell 2020; 56:192-201. [PMID: 33238148 DOI: 10.1016/j.devcel.2020.11.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/06/2020] [Accepted: 11/02/2020] [Indexed: 10/22/2022]
Abstract
The mitotic spindle is a microtubule-based assembly that separates the chromosomes during cell division. As the spindle is basically a mechanical micro machine, the understanding of its functioning is constantly motivating the development of experimental approaches based on mechanical perturbations, which are complementary to and work together with the classical genetics and biochemistry methods. Recent data emerging from these approaches in combination with theoretical modeling led to novel ideas and significant revisions of the basic concepts in the field. In this Perspective, we discuss the advances in the understanding of spindle mechanics, focusing on microtubule forces that control chromosome movements.
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Affiliation(s)
- Nenad Pavin
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia.
| | - Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
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28
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Kiewisz R, Müller-Reichert T, Fabig G. High-throughput screening of mitotic mammalian cells for electron microscopy using classic histological dyes. Methods Cell Biol 2020; 162:151-170. [PMID: 33707011 DOI: 10.1016/bs.mcb.2020.08.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We introduce a new workflow that allows screening and selection of staged mammalian cells in mitosis prior to subsequent electron microscopy. We mainly describe four improved steps of specimen preparation. Firstly, we describe a method to efficiently enrich mammalian cells and attach them to sapphire discs; secondly, we report on the use of 3D-printed containers to seed cells on coated sapphire discs for high-pressure freezing; thirdly, we take advantage of a specimen carrier that allows for an upside-down placing of sapphire discs without a second carrier or spacer ring to close the "sandwich"; and fourthly, we use histological dyes to stain DNA/chromatin during freeze-substitution. Out of 14 tested histological dyes, we routinely use four of them for visual inspection of mitotic cells by light microscopy. Applying this streamlined workflow, HeLa cells at different stages of mitosis can be selected for further ultrastructural analysis. The practical aspects of this approach will be discussed herein.
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Affiliation(s)
- Robert Kiewisz
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Thomas Müller-Reichert
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.
| | - Gunar Fabig
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
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29
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Nazockdast E, Redemann S. Mechanics of the spindle apparatus. Semin Cell Dev Biol 2020; 107:91-102. [PMID: 32747191 DOI: 10.1016/j.semcdb.2020.06.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 06/02/2020] [Accepted: 06/30/2020] [Indexed: 12/01/2022]
Abstract
During mitosis microtubules self-organize to form a bipolar mitotic spindle structure, which positions the sister chromatids on the spindle mid-plane and separates them afterwards. Previous studies have identified many spindle associated proteins. Yet, we do not fully understand how these nanoscopic proteins lead to force generation through interactions of individual microtubules, motor proteins and chromosomes, and how a large number of these local interactions ultimately determine the structure and mechanics of the spindle in micron scale. Here we review the current understanding and open questions related to the structure and mechanics of the mitotic spindle. We then discuss how a combination of electron microscopy and computational modeling can be used to tackle some of these open questions.
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Affiliation(s)
- Ehssan Nazockdast
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3250, USA.
| | - Stefanie Redemann
- Center for Membrane and Cell Physiology & Department of Molecular Physiology and Biological Physics, University of Virginia, School of Medicine, Charlottesville, VA, USA.
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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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Kinesin-14 motors drive a right-handed helical motion of antiparallel microtubules around each other. Nat Commun 2020; 11:2565. [PMID: 32444784 PMCID: PMC7244531 DOI: 10.1038/s41467-020-16328-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Accepted: 04/08/2020] [Indexed: 12/30/2022] Open
Abstract
Within the mitotic spindle, kinesin motors cross-link and slide overlapping microtubules. Some of these motors exhibit off-axis power strokes, but their impact on motility and force generation in microtubule overlaps has not been investigated. Here, we develop and utilize a three-dimensional in vitro motility assay to explore kinesin-14, Ncd, driven sliding of cross-linked microtubules. We observe that free microtubules, sliding on suspended microtubules, not only rotate around their own axis but also move around the suspended microtubules with right-handed helical trajectories. Importantly, the associated torque is large enough to cause microtubule twisting and coiling. Further, our technique allows us to measure the in situ spatial extension of the motors between cross-linked microtubules to be about 20 nm. We argue that the capability of microtubule-crosslinking kinesins to cause helical motion of overlapping microtubules around each other allows for flexible filament organization, roadblock circumvention and torque generation in the mitotic spindle. Some kinesins exhibit off-axis power strokes but their impact on motility and force generation in microtubule overlaps has not been investigated so far. Here authors use a 3D in vitro motility assay and find that Ndc’s off-axis motor forces generate torque in antiparallel microtubules which causes microtubule twisting and coiling.
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32
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Yang X, Li Z, Polyakova T, Dejneka A, Zablotskii V, Zhang X. Effect of static magnetic field on DNA synthesis: The interplay between DNA chirality and magnetic field left-right asymmetry. FASEB Bioadv 2020; 2:254-263. [PMID: 32259051 PMCID: PMC7133733 DOI: 10.1096/fba.2019-00045] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Revised: 05/26/2019] [Accepted: 02/03/2020] [Indexed: 12/13/2022] Open
Abstract
Interactions between magnetic fields (MFs) and living cells may stimulate a large variety of cellular responses to a MF, while the underlying intracellular mechanisms still remain a great puzzle. On a fundamental level, the MF - cell interaction is affected by the two broken symmetries: (a) left-right (LR) asymmetry of the MF and (b) chirality of DNA molecules carrying electric charges and subjected to the Lorentz force when moving in a MF. Here we report on the chirality-driven effect of static magnetic fields (SMFs) on DNA synthesis. This newly discovered effect reveals how the interplay between two fundamental features of symmetry in living and inanimate nature-DNA chirality and the inherent features of MFs to distinguish the left and right-manifests itself in different DNA synthesis rates in the upward and downward SMFs, consequently resulting in unequal cell proliferation for the two directions of the field. The interplay between DNA chirality and MF LR asymmetry will provide fundamental knowledge for many MF-induced biological phenotypes.
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Affiliation(s)
- Xingxing Yang
- High Magnetic Field LaboratoryKey Laboratory of High Magnetic Field and Ion Beam Physical BiologyHefei Institutes of Physical ScienceChinese Academy of SciencesHefeiChina
- Science Island Branch of Graduate SchoolUniversity of Science and Technology of ChinaHefeiChina
| | - Zhiyuan Li
- High Magnetic Field LaboratoryKey Laboratory of High Magnetic Field and Ion Beam Physical BiologyHefei Institutes of Physical ScienceChinese Academy of SciencesHefeiChina
| | - Tatyana Polyakova
- Institute of Physics of the Czech Academy of SciencesPragueCzech Republic
| | - Alexandr Dejneka
- Institute of Physics of the Czech Academy of SciencesPragueCzech Republic
| | - Vitalii Zablotskii
- Institute of Physics of the Czech Academy of SciencesPragueCzech Republic
| | - Xin Zhang
- High Magnetic Field LaboratoryKey Laboratory of High Magnetic Field and Ion Beam Physical BiologyHefei Institutes of Physical ScienceChinese Academy of SciencesHefeiChina
- Science Island Branch of Graduate SchoolUniversity of Science and Technology of ChinaHefeiChina
- Institutes of Physical Science and Information TechnologyAnhui UniversityHefeiChina
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33
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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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34
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Li J, Cheng L, Jiang H. Cell shape and intercellular adhesion regulate mitotic spindle orientation. Mol Biol Cell 2019; 30:2458-2468. [PMID: 31411941 PMCID: PMC6743358 DOI: 10.1091/mbc.e19-04-0227] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cell division orientation plays an essential role in tissue morphogenesis and cell fate decision. Recent studies showed that either cell shape or adhesion geometry can regulate the orientation of mitotic spindles and thereby the cell division orientation. However, how they together regulate the spindle orientation remains largely unclear. In this work, we use a general computational model to investigate the competitive mechanism of determining the spindle orientation between cell shape and intercellular adhesion in epithelial cells. We find the spindle orientation is dominated by the intercellular adhesion when the cell shape anisotropy is small, but dominated by the cell shape when the shape anisotropy is large. A strong adhesion and moderate adhesive size can ensure the planar division of epithelial cells with large apico-basal elongation. We also find the spindle orientation could be perpendicular to the adhesive region when only one side of the cell is adhered to an E-cadherin-coated matrix. But after the cell is compressed, the spindle orientation is governed by the cell shape and the spindle will be parallel to the adhesive region when the cell shape anisotropy is large. Finally, we demonstrate the competition between cell shape and tricellular junctions can also effectively regulate the spindle orientation.
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Affiliation(s)
- Jingchen Li
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Hefei National Laboratory for Physical Science at the Microscale, Department of Modern Mechanics, CAS Center for Excellence in Complex System Mechanics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Longcan Cheng
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Hefei National Laboratory for Physical Science at the Microscale, Department of Modern Mechanics, CAS Center for Excellence in Complex System Mechanics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Hongyuan Jiang
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Hefei National Laboratory for Physical Science at the Microscale, Department of Modern Mechanics, CAS Center for Excellence in Complex System Mechanics, University of Science and Technology of China, Hefei, Anhui 230026, China
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35
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Lamson AR, Edelmaier CJ, Glaser MA, Betterton MD. Theory of Cytoskeletal Reorganization during Cross-Linker-Mediated Mitotic Spindle Assembly. Biophys J 2019; 116:1719-1731. [PMID: 31010665 PMCID: PMC6507341 DOI: 10.1016/j.bpj.2019.03.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/25/2019] [Accepted: 03/06/2019] [Indexed: 11/29/2022] Open
Abstract
Cells grow, move, and respond to outside stimuli by large-scale cytoskeletal reorganization. A prototypical example of cytoskeletal remodeling is mitotic spindle assembly, during which microtubules nucleate, undergo dynamic instability, bundle, and organize into a bipolar spindle. Key mechanisms of this process include regulated filament polymerization, cross-linking, and motor-protein activity. Remarkably, using passive cross-linkers, fission yeast can assemble a bipolar spindle in the absence of motor proteins. We develop a torque-balance model that describes this reorganization because of dynamic microtubule bundles, spindle-pole bodies, the nuclear envelope, and passive cross-linkers to predict spindle-assembly dynamics. We compare these results to those obtained with kinetic Monte Carlo-Brownian dynamics simulations, which include cross-linker-binding kinetics and other stochastic effects. Our results show that rapid cross-linker reorganization to microtubule overlaps facilitates cross-linker-driven spindle assembly, a testable prediction for future experiments. Combining these two modeling techniques, we illustrate a general method for studying cytoskeletal network reorganization.
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Affiliation(s)
- Adam R Lamson
- Department of Physics, University of Colorado, Boulder, Colorado
| | | | - Matthew A Glaser
- Department of Physics, University of Colorado, Boulder, Colorado
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36
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Helical Twist and Rotational Forces in the Mitotic Spindle. Biomolecules 2019; 9:biom9040132. [PMID: 30939864 PMCID: PMC6523234 DOI: 10.3390/biom9040132] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/24/2019] [Accepted: 03/28/2019] [Indexed: 01/14/2023] Open
Abstract
The mitotic spindle segregates chromosomes into two daughter cells during cell division. This process relies on the precise regulation of forces acting on chromosomes as the cell progresses through mitosis. The forces in the spindle are difficult to directly measure using the available experimental techniques. Here, we review the ideas and recent advances of how forces can be determined from the spindle shape. By using these approaches, it has been shown that tension and compression coexist along a single kinetochore fiber, which are balanced by a bridging fiber between sister kinetochore fibers. An extension of this approach to three dimensions revealed that microtubule bundles have rich shapes, and extend not simply like meridians on the Earth’s surface but, rather, twisted in a helical manner. Such complex shapes are due to rotational forces, which, in addition to linear forces, act in the spindle and may be generated by motor proteins such as kinesin-5. These findings open new questions for future studies, to understand the mechanisms of rotational forces and reveal their biological roles in cells.
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37
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Anderson G, Dupré J, Wakefield JG. Drawing and the dynamic nature of living systems. eLife 2019; 8:46962. [PMID: 30916645 PMCID: PMC6436894 DOI: 10.7554/elife.46962] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 03/20/2019] [Indexed: 11/13/2022] Open
Abstract
Representing the dynamic nature of biological processes is a challenge. This article describes a collaborative project in which the authors – a philosopher of biology, an artist and a cell biologist – explore how best to represent the entire process of cell division in one connected image. This involved a series of group Drawing Labs, one-to-one sessions, and discussions between the authors. The drawings generated during the collaboration were then reviewed by four experts in cell division. We propose that such an approach has value, both in communicating the dynamic nature of biological processes and in generating new insights and hypotheses that can be tested by artists and scientists.
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Affiliation(s)
- Gemma Anderson
- Living Systems Institute, University of Exeter, Exeter, United Kingdom.,Egenis, The Centre for the Study of Life Sciences, University of Exeter, Exeter, United Kingdom
| | | | - James G Wakefield
- Living Systems Institute, University of Exeter, Exeter, United Kingdom
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38
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Affiliation(s)
| | - Daniel W. Gerlich
- IMBA–Institute of Molecular Biotechnology of the Austrian Academy of Sciences, 1030 Vienna, Austria
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39
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Bertin A, Lomakin A. Meeting report - Building the Cell 2018. J Cell Sci 2019; 132:132/5/jcs229765. [PMID: 30770478 DOI: 10.1242/jcs.229765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cell biologists from all around the world gathered in Paris on the 26 to 28 September 2018 to participate in the 3rd international meeting 'Building the Cell'. It was organized by Hélène Barelli, Arnaud Echard, Thierry Galli, Florence Niedergang, Manuel Théry and Marie Hélène Verlhac on behalf of the French Society for Cell Biology (SBCF) at the Institut Pasteur. Around 230 participants joined the meeting for stimulating talks, discussions, poster sessions, and a gala dinner on the Seine that included a music performance by the rock group 'Membrane Band'. The unifying theme of the meeting was the development of creative multidisciplinary approaches to understand cellular life at different scales in a dynamic and quantitative manner. Here, we summarize the results presented at the meeting and the emerging ideas from the different sessions.
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Affiliation(s)
- Aurelie Bertin
- Institut Curie, PSL Research University, CNRS UMR168, 75005 Paris, France
| | - Alexis Lomakin
- Centre for Stem Cells & Regenerative Medicine, King's College London, London SE1 9RT, UK
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40
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Metselaar L, Doostmohammadi A, Yeomans JM. Topological states in chiral active matter: Dynamic blue phases and active half-skyrmions. J Chem Phys 2019; 150:064909. [DOI: 10.1063/1.5085282] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Luuk Metselaar
- The Rudolf Peierls Centre for Theoretical Physics, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - Amin Doostmohammadi
- The Rudolf Peierls Centre for Theoretical Physics, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - Julia M. Yeomans
- The Rudolf Peierls Centre for Theoretical Physics, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
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