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Anjur-Dietrich MI, Gomez Hererra V, Farhadifar R, Wu H, Merta H, Bahmanyar S, Shelley MJ, Needleman DJ. Mechanics of spindle orientation in human mitotic cells is determined by pulling forces on astral microtubules and clustering of cortical dynein. Dev Cell 2024; 59:2429-2442.e4. [PMID: 38866013 DOI: 10.1016/j.devcel.2024.05.022] [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: 08/28/2023] [Revised: 04/03/2024] [Accepted: 05/17/2024] [Indexed: 06/14/2024]
Abstract
The forces that orient the spindle in human cells remain poorly understood due to a lack of direct mechanical measurements in mammalian systems. We use magnetic tweezers to measure the force on human mitotic spindles. Combining the spindle's measured resistance to rotation, the speed at which it rotates after laser ablating astral microtubules, and estimates of the number of ablated microtubules reveals that each microtubule contacting the cell cortex is subject to ∼5 pN of pulling force, suggesting that each is pulled on by an individual dynein motor. We find that the concentration of dynein at the cell cortex and extent of dynein clustering are key determinants of the spindle's resistance to rotation, with little contribution from cytoplasmic viscosity, which we explain using a biophysically based mathematical model. This work reveals how pulling forces on astral microtubules determine the mechanics of spindle orientation and demonstrates the central role of cortical dynein clustering.
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Affiliation(s)
- Maya I Anjur-Dietrich
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
| | - Vicente Gomez Hererra
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
| | - Reza Farhadifar
- Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
| | - Haiyin Wu
- Department of Physics, Harvard University, Cambridge, MA 02138, USA; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Holly Merta
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Shirin Bahmanyar
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Michael J Shelley
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA; Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
| | - Daniel J Needleman
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA; Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
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2
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Le Cunff Y, Chesneau L, Pastezeur S, Pinson X, Soler N, Fairbrass D, Mercat B, Rodriguez-Garcia R, Alayan Z, Abdouni A, de Neidhardt G, Costes V, Anjubault M, Bouvrais H, Héligon C, Pécréaux J. Unveiling inter-embryo variability in spindle length over time: Towards quantitative phenotype analysis. PLoS Comput Biol 2024; 20:e1012330. [PMID: 39236069 PMCID: PMC11376571 DOI: 10.1371/journal.pcbi.1012330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Accepted: 07/15/2024] [Indexed: 09/07/2024] Open
Abstract
How can inter-individual variability be quantified? Measuring many features per experiment raises the question of choosing them to recapitulate high-dimensional data. Tackling this challenge on spindle elongation phenotypes, we showed that only three typical elongation patterns describe spindle elongation in C. elegans one-cell embryo. These archetypes, automatically extracted from the experimental data using principal component analysis (PCA), accounted for more than 95% of inter-individual variability of more than 1600 experiments across more than 100 different conditions. The two first archetypes were related to spindle average length and anaphasic elongation rate. The third archetype, accounting for 6% of the variability, was novel and corresponded to a transient spindle shortening in late metaphase, reminiscent of kinetochore function-defect phenotypes. Importantly, these three archetypes were robust to the choice of the dataset and were found even considering only non-treated conditions. Thus, the inter-individual differences between genetically perturbed embryos have the same underlying nature as natural inter-individual differences between wild-type embryos, independently of the temperatures. We thus propose that beyond the apparent complexity of the spindle, only three independent mechanisms account for spindle elongation, weighted differently in the various conditions. Interestingly, the spindle-length archetypes covered both metaphase and anaphase, suggesting that spindle elongation in late metaphase is sufficient to predict the late anaphase length. We validated this idea using a machine-learning approach. Finally, given amounts of these three archetypes could represent a quantitative phenotype. To take advantage of this, we set out to predict interacting genes from a seed based on the PCA coefficients. We exemplified this firstly on the role of tpxl-1 whose homolog tpx2 is involved in spindle microtubule branching, secondly the mechanism regulating metaphase length, and thirdly the central spindle players which set the length at anaphase. We found novel interactors not in public databases but supported by recent experimental publications.
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Affiliation(s)
- Yann Le Cunff
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Laurent Chesneau
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Sylvain Pastezeur
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Xavier Pinson
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Nina Soler
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Danielle Fairbrass
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Benjamin Mercat
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Ruddi Rodriguez-Garcia
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Zahraa Alayan
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Ahmed Abdouni
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Gary de Neidhardt
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Valentin Costes
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Mélodie Anjubault
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Hélène Bouvrais
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Christophe Héligon
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Jacques Pécréaux
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
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3
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Kroll J, Renkawitz J. Principles of organelle positioning in motile and non-motile cells. EMBO Rep 2024; 25:2172-2187. [PMID: 38627564 PMCID: PMC11094012 DOI: 10.1038/s44319-024-00135-4] [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: 11/13/2023] [Revised: 03/15/2024] [Accepted: 04/04/2024] [Indexed: 05/16/2024] Open
Abstract
Cells are equipped with asymmetrically localised and functionally specialised components, including cytoskeletal structures and organelles. Positioning these components to specific intracellular locations in an asymmetric manner is critical for their functionality and affects processes like immune responses, tissue maintenance, muscle functionality, and neurobiology. Here, we provide an overview of strategies to actively move, position, and anchor organelles to specific locations. By conceptualizing the cytoskeletal forces and the organelle-to-cytoskeleton connectivity, we present a framework of active positioning of both membrane-enclosed and membrane-less organelles. Using this framework, we discuss how different principles of force generation and organelle anchorage are utilised by different cells, such as mesenchymal and amoeboid cells, and how the microenvironment influences the plasticity of organelle positioning. Given that motile cells face the challenge of coordinating the positioning of their content with cellular motion, we particularly focus on principles of organelle positioning during migration. In this context, we discuss novel findings on organelle positioning by anchorage-independent mechanisms and their advantages and disadvantages in motile as well as stationary cells.
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Affiliation(s)
- Janina Kroll
- Biomedical Center, Walter Brendel Center of Experimental Medicine, Institute of Cardiovascular Physiology and Pathophysiology, Klinikum der Universität, Ludwig Maximilians Universität München, Munich, Germany
| | - Jörg Renkawitz
- Biomedical Center, Walter Brendel Center of Experimental Medicine, Institute of Cardiovascular Physiology and Pathophysiology, Klinikum der Universität, Ludwig Maximilians Universität München, Munich, Germany.
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4
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Rosfelter A, de Labbey G, Chenevert J, Dumollard R, Schaub S, Machaty Z, Besnardeau L, Gonzalez Suarez D, Hebras C, Turlier H, Burgess DR, McDougall A. Reduction of cortical pulling at mitotic entry facilitates aster centration. J Cell Sci 2024; 137:jcs262037. [PMID: 38469748 DOI: 10.1242/jcs.262037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 02/23/2024] [Indexed: 03/13/2024] Open
Abstract
Equal cell division relies upon astral microtubule-based centering mechanisms, yet how the interplay between mitotic entry, cortical force generation and long astral microtubules leads to symmetric cell division is not resolved. We report that a cortically located sperm aster displaying long astral microtubules that penetrate the whole zygote does not undergo centration until mitotic entry. At mitotic entry, we find that microtubule-based cortical pulling is lost. Quantitative measurements of cortical pulling and cytoplasmic pulling together with physical simulations suggested that a wavelike loss of cortical pulling at mitotic entry leads to aster centration based on cytoplasmic pulling. Cortical actin is lost from the cortex at mitotic entry coincident with a fall in cortical tension from ∼300pN/µm to ∼100pN/µm. Following the loss of cortical force generators at mitotic entry, long microtubule-based cytoplasmic pulling is sufficient to displace the aster towards the cell center. These data reveal how mitotic aster centration is coordinated with mitotic entry in chordate zygotes.
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Affiliation(s)
- Anne Rosfelter
- Laboratoire de Biologie du Developpement de Villefranche-sur-mer, Institut de la Mer de Villefranche-sur-mer, Sorbonne Université, CNRS, 06230 Villefranche-sur-mer, France
| | - Ghislain de Labbey
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS UMR7241 / INSERM U1050, Université PSL, 75002 Paris, France
| | - Janet Chenevert
- Laboratoire de Biologie du Developpement de Villefranche-sur-mer, Institut de la Mer de Villefranche-sur-mer, Sorbonne Université, CNRS, 06230 Villefranche-sur-mer, France
| | - Rémi Dumollard
- Laboratoire de Biologie du Developpement de Villefranche-sur-mer, Institut de la Mer de Villefranche-sur-mer, Sorbonne Université, CNRS, 06230 Villefranche-sur-mer, France
| | - Sebastien Schaub
- Laboratoire de Biologie du Developpement de Villefranche-sur-mer, Institut de la Mer de Villefranche-sur-mer, Sorbonne Université, CNRS, 06230 Villefranche-sur-mer, France
| | - Zoltan Machaty
- Laboratoire de Biologie du Developpement de Villefranche-sur-mer, Institut de la Mer de Villefranche-sur-mer, Sorbonne Université, CNRS, 06230 Villefranche-sur-mer, France
| | - Lydia Besnardeau
- Laboratoire de Biologie du Developpement de Villefranche-sur-mer, Institut de la Mer de Villefranche-sur-mer, Sorbonne Université, CNRS, 06230 Villefranche-sur-mer, France
| | - Daniel Gonzalez Suarez
- Laboratoire de Biologie du Developpement de Villefranche-sur-mer, Institut de la Mer de Villefranche-sur-mer, Sorbonne Université, CNRS, 06230 Villefranche-sur-mer, France
| | - Céline Hebras
- Laboratoire de Biologie du Developpement de Villefranche-sur-mer, Institut de la Mer de Villefranche-sur-mer, Sorbonne Université, CNRS, 06230 Villefranche-sur-mer, France
| | - Hervé Turlier
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS UMR7241 / INSERM U1050, Université PSL, 75002 Paris, France
| | - David R Burgess
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA
| | - Alex McDougall
- Laboratoire de Biologie du Developpement de Villefranche-sur-mer, Institut de la Mer de Villefranche-sur-mer, Sorbonne Université, CNRS, 06230 Villefranche-sur-mer, France
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5
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Anjur-Dietrich MI, Hererra VG, Farhadifar R, Wu H, Merta H, Bahmanyar S, Shelley MJ, Needleman DJ. Clustering of cortical dynein regulates the mechanics of spindle orientation in human mitotic cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.11.557210. [PMID: 37745442 PMCID: PMC10515834 DOI: 10.1101/2023.09.11.557210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The forces which orient the spindle in human cells remain poorly understood due to a lack of direct mechanical measurements in mammalian systems. We use magnetic tweezers to measure the force on human mitotic spindles. Combining the spindle's measured resistance to rotation, the speed it rotates after laser ablating astral microtubules, and estimates of the number of ablated microtubules reveals that each microtubule contacting the cell cortex is subject to ~1 pN of pulling force, suggesting that each is pulled on by an individual dynein motor. We find that the concentration of dynein at the cell cortex and extent of dynein clustering are key determinants of the spindle's resistance to rotation, with little contribution from cytoplasmic viscosity, which we explain using a biophysically based mathematical model. This work reveals how pulling forces on astral microtubules determine the mechanics of spindle orientation and demonstrates the central role of cortical dynein clustering.
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Affiliation(s)
- Maya I. Anjur-Dietrich
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Vicente Gomez Hererra
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
| | - Reza Farhadifar
- Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
| | - Haiyin Wu
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Holly Merta
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Shirin Bahmanyar
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Michael J. Shelley
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
- Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
| | - Daniel J. Needleman
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
- Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
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6
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Ali A, Stukenberg PT. Aurora kinases: Generators of spatial control during mitosis. Front Cell Dev Biol 2023; 11:1139367. [PMID: 36994100 PMCID: PMC10040841 DOI: 10.3389/fcell.2023.1139367] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 03/02/2023] [Indexed: 03/15/2023] Open
Abstract
Cell division events require regulatory systems to ensure that events happen in a distinct order. The classic view of temporal control of the cell cycle posits that cells order events by linking them to changes in Cyclin Dependent Kinase (CDK) activities. However, a new paradigm is emerging from studies of anaphase where chromatids separate at the central metaphase plate and then move to opposite poles of the cell. These studies suggest that distinct events are ordered depending upon the location of each chromosome along its journey from the central metaphase plate to the elongated spindle poles. This system is dependent upon a gradient of Aurora B kinase activity that emerges during anaphase and acts as a spatial beacon to control numerous anaphase/telophase events and cytokinesis. Recent studies also suggest that Aurora A kinase activity specifies proximity of chromosomes or proteins to spindle poles during prometaphase. Together these studies argue that a key role for Aurora kinases is to provide spatial information that controls events depending upon the location of chromosomes or proteins along the mitotic spindle.
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Affiliation(s)
| | - P. Todd Stukenberg
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Charlottesville, VA, United States
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7
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Dor YB, Kafri Y, Kardar M, Tailleur J. Passive objects in confined active fluids: A localization transition. Phys Rev E 2022; 106:044604. [PMID: 36397585 DOI: 10.1103/physreve.106.044604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
We study how walls confining active fluids interact with asymmetric passive objects placed in their bulk. We show that the objects experience nonconservative long-ranged forces mediated by the active bath. To leading order, these forces can be computed using a generalized image theorem. The walls repel asymmetric objects, irrespective of their microscopic properties or their orientations. For circular cavities, we demonstrate how this may lead to the localization of asymmetric objects in the center of the cavity, something impossible for symmetric ones.
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Affiliation(s)
- Ydan Ben Dor
- Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Yariv Kafri
- Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Mehran Kardar
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Julien Tailleur
- Université Paris Cité, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205 Paris, France
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8
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Bai L, Mitchison TJ. Spring-like behavior of cytoplasm holds the mitotic spindle in place. Proc Natl Acad Sci U S A 2022; 119:e2203036119. [PMID: 35324318 PMCID: PMC9169080 DOI: 10.1073/pnas.2203036119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Luolan Bai
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
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9
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Multiple asters organize the yolk microtubule network during dclk2-GFP zebrafish epiboly. Sci Rep 2022; 12:4072. [PMID: 35260695 PMCID: PMC8904445 DOI: 10.1038/s41598-022-07747-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 02/21/2022] [Indexed: 11/25/2022] Open
Abstract
It is known that the organization of microtubule (MT) networks in cells is orchestrated by subcellular structures named MT organizing centers (MTOCs). In this work, we use Light Sheet Fluorescence and Confocal Microscopy to investigate how the MT network surrounding the spherical yolk is arranged in the dclk2-GFP zebrafish transgenic line. We found that during epiboly the MT network is organized by multiple aster-like MTOCS. These structures form rings around the yolk sphere. Importantly, in wt embryos, aster-like MTOCs are only found upon pharmacological or genetic induction. Using our microscopy approach, we underscore the variability in the number of such asters in the transgenic line and report on the variety of global configurations of the yolk MT network. The asters’ morphology, dynamics, and their distribution in the yolk sphere are also analyzed. We propose that these features are tightly linked to epiboly timing and geometry. Key molecules are identified which support this asters role as MTOCs, where MT nucleation and growth take place. We conclude that the yolk MT network of dclk2-GFP transgenic embryos can be used as a model to organize microtubules in a spherical geometry by means of multiple MTOCs.
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10
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de-Carvalho J, Tlili S, Hufnagel L, Saunders TE, Telley IA. Aster repulsion drives short-ranged ordering in the Drosophila syncytial blastoderm. Development 2022; 149:274085. [DOI: 10.1242/dev.199997] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 12/17/2021] [Indexed: 12/28/2022]
Abstract
ABSTRACT
Biological systems are highly complex, yet notably ordered structures can emerge. During syncytial stage development of the Drosophila melanogaster embryo, nuclei synchronously divide for nine cycles within a single cell, after which most of the nuclei reach the cell cortex. The arrival of nuclei at the cortex occurs with remarkable positional order, which is important for subsequent cellularisation and morphological transformations. Yet, the mechanical principles underlying this lattice-like positional order of nuclei remain untested. Here, using quantification of nuclei position and division orientation together with embryo explants, we show that short-ranged repulsive interactions between microtubule asters ensure the regular distribution and maintenance of nuclear positions in the embryo. Such ordered nuclear positioning still occurs with the loss of actin caps and even the loss of the nuclei themselves; the asters can self-organise with similar distribution to nuclei in the wild-type embryo. The explant assay enabled us to deduce the nature of the mechanical interaction between pairs of nuclei. We used this to predict how the nuclear division axis orientation changes upon nucleus removal from the embryo cortex, which we confirmed in vivo with laser ablation. Overall, we show that short-ranged microtubule-mediated repulsive interactions between asters are important for ordering in the early Drosophila embryo and minimising positional irregularity.
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Affiliation(s)
- Jorge de-Carvalho
- Physics of Intracellular Organization Group, Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
| | - Sham Tlili
- Mechanobiology Institute, National University of Singapore, 117411 Singapore
| | - Lars Hufnagel
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Timothy E. Saunders
- Mechanobiology Institute, National University of Singapore, 117411 Singapore
- Department of Biological Sciences, National University of Singapore, 117411Singapore
- Institute of Molecular and Cellular Biology, A*Star, Proteos, 138632 Singapore
- Warwick Medical School, University of Warwick, Coventry, CV4 7HL, UK
| | - Ivo A. Telley
- Physics of Intracellular Organization Group, Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
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11
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Deshpande O, de-Carvalho J, Vieira DV, Telley IA. Astral microtubule cross-linking safeguards uniform nuclear distribution in the Drosophila syncytium. J Cell Biol 2022; 221:212810. [PMID: 34766978 PMCID: PMC8594625 DOI: 10.1083/jcb.202007209] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/24/2021] [Accepted: 10/20/2021] [Indexed: 12/16/2022] Open
Abstract
The early insect embryo develops as a multinucleated cell distributing the genome uniformly to the cell cortex. Mechanistic insight for nuclear positioning beyond cytoskeletal requirements is missing. Contemporary hypotheses propose actomyosin-driven cytoplasmic movement transporting nuclei or repulsion of neighbor nuclei driven by microtubule motors. Here, we show that microtubule cross-linking by Feo and Klp3A is essential for nuclear distribution and internuclear distance maintenance in Drosophila. Germline knockdown causes irregular, less-dense nuclear delivery to the cell cortex and smaller distribution in ex vivo embryo explants. A minimal internuclear distance is maintained in explants from control embryos but not from Feo-inhibited embryos, following micromanipulation-assisted repositioning. A dimerization-deficient Feo abolishes nuclear separation in embryo explants, while the full-length protein rescues the genetic knockdown. We conclude that Feo and Klp3A cross-linking of antiparallel microtubule overlap generates a length-regulated mechanical link between neighboring microtubule asters. Enabled by a novel experimental approach, our study illuminates an essential process of embryonic multicellularity.
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Affiliation(s)
- Ojas Deshpande
- Instituto Gulbenkian de Ciência, Fundação Calouste Gulbenkian, Oeiras, Portugal
| | - Jorge de-Carvalho
- Instituto Gulbenkian de Ciência, Fundação Calouste Gulbenkian, Oeiras, Portugal
| | - Diana V Vieira
- Instituto Gulbenkian de Ciência, Fundação Calouste Gulbenkian, Oeiras, Portugal
| | - Ivo A Telley
- Instituto Gulbenkian de Ciência, Fundação Calouste Gulbenkian, Oeiras, Portugal
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12
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Deshpande O, Telley IA. Nuclear positioning during development: Pushing, pulling and flowing. Semin Cell Dev Biol 2021; 120:10-21. [PMID: 34642103 DOI: 10.1016/j.semcdb.2021.09.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 09/29/2021] [Accepted: 09/30/2021] [Indexed: 01/13/2023]
Abstract
The positioning of the nucleus, the central organelle of the cell, is an active and regulated process crucially linked to cell cycle, differentiation, migration, and polarity. Alterations in positioning have been correlated with cell and tissue function deficiency and genetic or chemical manipulation of nuclear position is embryonic lethal. Nuclear positioning is a precursor for symmetric or asymmetric cell division which is accompanied by fate determination of the daughter cells. Nuclear positioning also plays a key role during early embryonic developmental stages in insects, such as Drosophila, where hundreds of nuclei divide without cytokinesis and are distributed within the large syncytial embryo at roughly regular spacing. While the cytoskeletal elements and the linker proteins to the nucleus are fairly well characterised, including some of the force generating elements driving nuclear movement, there is considerable uncertainty about the biophysical mechanism of nuclear positioning, while the field is debating different force models. In this review, we highlight the current body of knowledge, discuss cell context dependent models of nuclear positioning, and outline open questions.
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Affiliation(s)
- Ojas Deshpande
- Instituto Gulbenkian de Ciência (IGC), Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal
| | - Ivo A Telley
- Instituto Gulbenkian de Ciência (IGC), Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal.
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13
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The Cytoskeleton and Its Roles in Self-Organization Phenomena: Insights from Xenopus Egg Extracts. Cells 2021; 10:cells10092197. [PMID: 34571847 PMCID: PMC8465277 DOI: 10.3390/cells10092197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/18/2021] [Accepted: 08/21/2021] [Indexed: 01/11/2023] Open
Abstract
Self-organization of and by the cytoskeleton is central to the biology of the cell. Since their introduction in the early 1980s, cytoplasmic extracts derived from the eggs of the African clawed-frog, Xenopus laevis, have flourished as a major experimental system to study the various facets of cytoskeleton-dependent self-organization. Over the years, the many investigations that have used these extracts uniquely benefited from their simplified cell cycle, large experimental volumes, biochemical tractability and cell-free nature. Here, we review the contributions of egg extracts to our understanding of the cytoplasmic aspects of self-organization by the microtubule and the actomyosin cytoskeletons as well as the importance of cytoskeletal filaments in organizing nuclear structure and function.
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14
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Khetan N, Pruliere G, Hebras C, Chenevert J, Athale CA. Self-organized optimal packing of kinesin-5-driven microtubule asters scales with cell size. J Cell Sci 2021; 134:jcs257543. [PMID: 34080632 DOI: 10.1242/jcs.257543] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Accepted: 04/18/2021] [Indexed: 12/18/2022] Open
Abstract
Radial microtubule (MT) arrays or asters determine cell geometry in animal cells. Multiple asters interacting with motors, such as those in syncytia, form intracellular patterns, but the mechanical principles behind this are not clear. Here, we report that oocytes of the marine ascidian Phallusia mammillata treated with the drug BI-D1870 spontaneously form cytoplasmic MT asters, or cytasters. These asters form steady state segregation patterns in a shell just under the membrane. Cytaster centers tessellate the oocyte cytoplasm, that is divide it into polygonal structures, dominated by hexagons, in a kinesin-5-dependent manner, while inter-aster MTs form 'mini-spindles'. A computational model of multiple asters interacting with kinesin-5 can reproduce both tessellation patterns and mini-spindles in a manner specific to the number of MTs per aster, MT lengths and kinesin-5 density. Simulations predict that the hexagonal tessellation patterns scale with increasing cell size, when the packing fraction of asters in cells is ∼1.6. This self-organized in vivo tessellation by cytasters is comparable to the 'circle packing problem', suggesting that there is an intrinsic mechanical pattern-forming module that is potentially relevant to understanding the role of collective mechanics of cytoskeletal elements in embryogenesis. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Neha Khetan
- Division of Biology, IISER Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
| | - Gérard Pruliere
- LBDV, Sorbonne Universite/CNRS, 06230 Villefranche-sur-Mer, France
| | - Celine Hebras
- LBDV, Sorbonne Universite/CNRS, 06230 Villefranche-sur-Mer, France
| | - Janet Chenevert
- LBDV, Sorbonne Universite/CNRS, 06230 Villefranche-sur-Mer, France
| | - Chaitanya A Athale
- Division of Biology, IISER Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
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15
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Bouvrais H, Chesneau L, Le Cunff Y, Fairbrass D, Soler N, Pastezeur S, Pécot T, Kervrann C, Pécréaux J. The coordination of spindle-positioning forces during the asymmetric division of the Caenorhabditis elegans zygote. EMBO Rep 2021; 22:e50770. [PMID: 33900015 DOI: 10.15252/embr.202050770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 02/22/2021] [Accepted: 03/03/2021] [Indexed: 12/28/2022] Open
Abstract
In Caenorhabditis elegans zygote, astral microtubules generate forces essential to position the mitotic spindle, by pushing against and pulling from the cortex. Measuring microtubule dynamics there, we revealed the presence of two populations, corresponding to pulling and pushing events. It offers a unique opportunity to study, under physiological conditions, the variations of both spindle-positioning forces along space and time. We propose a threefold control of pulling force, by polarity, spindle position and mitotic progression. We showed that the sole anteroposterior asymmetry in dynein on-rate, encoding pulling force imbalance, is sufficient to cause posterior spindle displacement. The positional regulation, reflecting the number of microtubule contacts in the posterior-most region, reinforces this imbalance only in late anaphase. Furthermore, we exhibited the first direct proof that dynein processivity increases along mitosis. It reflects the temporal control of pulling forces, which strengthens at anaphase onset following mitotic progression and independently from chromatid separation. In contrast, the pushing force remains constant and symmetric and contributes to maintaining the spindle at the cell centre during metaphase.
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Affiliation(s)
| | | | - Yann Le Cunff
- CNRS, IGDR - UMR 6290, University of Rennes, Rennes, France
| | | | - Nina Soler
- CNRS, IGDR - UMR 6290, University of Rennes, Rennes, France
| | | | - Thierry Pécot
- INRIA, Centre Rennes - Bretagne Atlantique, Rennes, France
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16
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Yukawa M, Teratani Y, Toda T. Escape from mitotic catastrophe by actin-dependent nuclear displacement in fission yeast. iScience 2021; 24:102031. [PMID: 33506191 PMCID: PMC7814194 DOI: 10.1016/j.isci.2020.102031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 12/17/2020] [Accepted: 12/29/2020] [Indexed: 11/23/2022] Open
Abstract
Eukaryotic cells position the nucleus within the proper intracellular space, thereby safeguarding a variety of cellular processes. In fission yeast, the interphase nucleus is placed in the cell middle in a microtubule-dependent manner. By contrast, how the mitotic nucleus is positioned remains elusive. Here we show that several cell-cycle mutants that arrest in mitosis all displace the nucleus toward one end of the cell. Intriguingly, the actin cytoskeleton is responsible for nuclear movement. Time-lapse live imaging indicates that mitosis-specific F-actin cables possibly push the nucleus through direct interaction with the nuclear envelope, and subsequently actomyosin ring constriction further shifts the nucleus away from the center. This nuclear movement is beneficial, because if the nuclei were retained in the center, unseparated chromosomes would be intersected by the contractile actin ring and the septum, imposing the lethal cut phenotype. Thus, fission yeast escapes from mitotic catastrophe by means of actin-dependent nuclear movement. Actin-dependent mitotic nuclear positioning in fission yeast Actin cables and ring closure drive nuclear displacement upon mitotic arrest Nuclear displacement evades cut-mediated cell death Survivors resume cell division as diploids
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Affiliation(s)
- Masashi Yukawa
- Hiroshima Research Center for Healthy Aging (HiHA), Hiroshima University, Higashi-Hiroshima 739-8530, Japan.,Laboratory of Molecular and Chemical Cell Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Yasuhiro Teratani
- Laboratory of Molecular and Chemical Cell Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Takashi Toda
- Hiroshima Research Center for Healthy Aging (HiHA), Hiroshima University, Higashi-Hiroshima 739-8530, Japan.,Laboratory of Molecular and Chemical Cell Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
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17
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Sulerud T, Sami AB, Li G, Kloxin A, Oakey J, Gatlin J. Microtubule-dependent pushing forces contribute to long-distance aster movement and centration in Xenopus laevis egg extracts. Mol Biol Cell 2020; 31:2791-2802. [PMID: 33026931 PMCID: PMC7851858 DOI: 10.1091/mbc.e20-01-0088] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
During interphase of the eukaryotic cell cycle, the microtubule (MT) cytoskeleton serves as both a supportive scaffold for organelles and an arborized system of tracks for intracellular transport. At the onset of mitosis, the position of the astral MT network, specifically its center, determines the eventual location of the spindle apparatus and ultimately the cytokinetic furrow. Positioning of the MT aster often results in its movement to the center of a cell, even in large blastomeres hundreds of microns in diameter. This translocation requires positioning forces, yet how these forces are generated and then integrated within cells of various sizes and geometries remains an open question. Here we describe a method that combines microfluidics, hydrogels, and Xenopus laevis egg extract to investigate the mechanics of aster movement and centration. We determined that asters were able to find the center of artificial channels and annular cylinders, even when cytoplasmic dynein-dependent pulling mechanisms were inhibited. Characterization of aster movement away from V-shaped hydrogel barriers provided additional evidence for a MT-based pushing mechanism. Importantly, the distance over which this mechanism seemed to operate was longer than that predicted by radial aster growth models, agreeing with recent models of a more complex MT network architecture within the aster.
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Affiliation(s)
- Taylor Sulerud
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071.,Cell Organization and Division Group, Marine Biological Laboratory, Woods Hole, MA 02543
| | | | - Guihe Li
- Department of Chemical Engineering, University of Wyoming, Laramie, WY 82071
| | - April Kloxin
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716
| | - John Oakey
- Department of Chemical Engineering, University of Wyoming, Laramie, WY 82071.,Cell Organization and Division Group, Marine Biological Laboratory, Woods Hole, MA 02543
| | - Jesse Gatlin
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071.,Cell Organization and Division Group, Marine Biological Laboratory, Woods Hole, MA 02543
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18
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Burakov AV, Nadezhdina ES. Centering and Shifting of Centrosomes in Cells. Cells 2020; 9:E1351. [PMID: 32485978 PMCID: PMC7348834 DOI: 10.3390/cells9061351] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 05/24/2020] [Accepted: 05/27/2020] [Indexed: 12/16/2022] Open
Abstract
Centrosomes have a nonrandom localization in the cells: either they occupy the centroid of the zone free of the actomyosin cortex or they are shifted to the edge of the cell, where their presence is justified from a functional point of view, for example, to organize additional microtubules or primary cilia. This review discusses centrosome placement options in cultured and in situ cells. It has been proven that the central arrangement of centrosomes is due mainly to the pulling microtubules forces developed by dynein located on the cell cortex and intracellular vesicles. The pushing forces from dynamic microtubules and actomyosin also contribute, although the molecular mechanisms of their action have not yet been elucidated. Centrosomal displacement is caused by external cues, depending on signaling, and is drawn through the redistribution of dynein, the asymmetrization of microtubules through the capture of their plus ends, and the redistribution of actomyosin, which, in turn, is associated with basal-apical cell polarization.
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Affiliation(s)
- Anton V. Burakov
- A. N. Belozersky Institute of Physico-Chemical Biology, M. V. Lomonosov Moscow State University, 119991 Moscow, Russia;
| | - Elena S. Nadezhdina
- Institute of Protein Research of Russian Academy of Science, Pushchino, 142290 Moscow Region, Russia
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19
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Ierushalmi N, Malik-Garbi M, Manhart A, Abu Shah E, Goode BL, Mogilner A, Keren K. Centering and symmetry breaking in confined contracting actomyosin networks. eLife 2020; 9:55368. [PMID: 32314730 PMCID: PMC7173961 DOI: 10.7554/elife.55368] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 03/19/2020] [Indexed: 11/13/2022] Open
Abstract
Centering and decentering of cellular components is essential for internal organization of cells and their ability to perform basic cellular functions such as division and motility. How cells achieve proper localization of their organelles is still not well-understood, especially in large cells such as oocytes. Here, we study actin-based positioning mechanisms in artificial cells with persistently contracting actomyosin networks, generated by encapsulating cytoplasmic Xenopus egg extracts into cell-sized ‘water-in-oil’ droplets. We observe size-dependent localization of the contraction center, with a symmetric configuration in larger cells and a polar one in smaller cells. Centering is achieved via a hydrodynamic mechanism based on Darcy friction between the contracting network and the surrounding cytoplasm. During symmetry breaking, transient attachments to the cell boundary drive the contraction center to a polar location. The centering mechanism is cell-cycle dependent and weakens considerably during interphase. Our findings demonstrate a robust, yet tunable, mechanism for subcellular localization. In order to survive, cells need to react to their environment and change their shape or the localization of their internal components. For example, the nucleus – the compartment that contains the genetic information – is often localized at the center of the cell, but it can also be positioned at the side, for instance when cells move or divide asymmetrically. Cells use multiple positioning mechanisms to move their internal components, including a process that relies on networks of filaments made of a protein known as actin. These networks are constantly remodeled as actin proteins are added and removed from the network. Embedded molecular motors can cause the network of actin filaments to contract and push or pull on the compartments. Yet, the exact way these networks localize components in the cell remains unclear, especially in eggs and other large cells. To investigate this question, Ierushalmi et al. studied the actin networks in artificial cells that they created by enclosing the contents of frog eggs in small droplets surrounded by oil. This showed that the networks contracted either to the center of the cell or to its side. Friction between the contracting actin network and the fluid in the cell generated a force that tends to push the contraction center towards the middle of the cell. In larger cells, this led to the centering of the actin network. In smaller cells however, the network transiently attached to the boundary of the cell, leading the contraction center to be pulled to one side. By developing simpler artificial cells that mimic the positioning processes seen in real-life cells, Ierushalmi et al. discovered new mechanisms for how cells may center or de-center their components. This knowledge may be useful to understand diseases that can emerge when the nucleus or other compartments fail to move to the right location, and which are associated with certain organs developing incorrectly.
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Affiliation(s)
- Niv Ierushalmi
- Department of Physics, Technion- Israel Institute of Technology, Haifa, Israel
| | - Maya Malik-Garbi
- Department of Physics, Technion- Israel Institute of Technology, Haifa, Israel
| | - Angelika Manhart
- Department of Mathematics, University College London, London, United Kingdom
| | - Enas Abu Shah
- Department of Physics, Technion- Israel Institute of Technology, Haifa, Israel.,Kennedy Institute of Rheumatology, University of Oxford, Oxford, United Kingdom
| | - Bruce L Goode
- Department of Biology, Brandeis University, Waltham, United States
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences and Department of Biology, New York University, New York, United States
| | - 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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20
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Xie J, Minc N. Cytoskeleton Force Exertion in Bulk Cytoplasm. Front Cell Dev Biol 2020; 8:69. [PMID: 32117991 PMCID: PMC7031414 DOI: 10.3389/fcell.2020.00069] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 01/27/2020] [Indexed: 01/20/2023] Open
Abstract
The microtubule and actin cytoskeletons generate forces essential to position centrosomes, nuclei, and spindles for division plane specification. While the largest body of work has documented force exertion at, or close to the cell surface, mounting evidence suggests that cytoskeletal polymers can also produce significant forces directly from within the cytoplasm. Molecular motors such as kinesin or dynein may for instance displace cargos and endomembranes in the viscous cytoplasm yielding friction forces that pull or push microtubules. Similarly, the dynamics of bulk actin assembly/disassembly or myosin-dependent contractions produce cytoplasmic forces which influence the spatial organization of cells in a variety of processes. We here review the molecular and physical mechanisms supporting bulk cytoplasmic force generation by the cytoskeleton, their limits and relevance to organelle positioning, with a particular focus on cell division.
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Affiliation(s)
- Jing Xie
- Institut Jacques Monod, Université de Paris, CNRS UMR 7592, Paris, France
| | - Nicolas Minc
- Institut Jacques Monod, Université de Paris, CNRS UMR 7592, Paris, France
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21
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Abstract
The assembly of the mitotic spindle and the subsequent segregation of sister chromatids are based on the self-organized action of microtubule filaments, motor proteins, and other microtubule-associated proteins, which constitute the fundamental force-generating elements in the system. Many of the components in the spindle have been identified, but until recently it remained unclear how their collective behaviors resulted in such a robust bipolar structure. Here, we review the current understanding of the physics of the metaphase spindle that is only now starting to emerge.
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Affiliation(s)
- David Oriola
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307, Dresden, Germany; .,Max Planck Institute for the Physics of Complex Systems, 01187, Dresden, Germany.,Center for Systems Biology Dresden, 01307, Dresden, Germany
| | - Daniel J Needleman
- School of Engineering and Applied Sciences, Department of Molecular and Cellular Biology, and FAS Center for Systems Biology, Harvard University, Cambridge, Massachusetts 021382, USA
| | - Jan Brugués
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307, Dresden, Germany; .,Max Planck Institute for the Physics of Complex Systems, 01187, Dresden, Germany.,Center for Systems Biology Dresden, 01307, Dresden, Germany
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22
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Abstract
Amphibian oocytes and embryos are classical models to study cellular and developmental processes. For these studies, it is often advantageous to visualize protein organization. However, the large size and yolk distribution make imaging of deep structures in amphibian zygotes challenging. Here we describe in detail immunofluorescence (IF) protocols for imaging microtubule assemblies in early amphibian development. We developed these protocols to elucidate how the cell division machinery adapts to drastic changes in embryonic cell sizes. We describe how to image mitotic spindles, microtubule asters, chromosomes, and nuclei in whole-mount embryos, even when they are hundreds of micrometers removed from the embryo's surface. Though the described methods were optimized for microtubule assemblies, they have also proven useful for the visualization of other proteins.
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23
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Shrestha S, Hazelbaker M, Yount AL, Walczak CE. Emerging Insights into the Function of Kinesin-8 Proteins in Microtubule Length Regulation. Biomolecules 2018; 9:biom9010001. [PMID: 30577528 PMCID: PMC6359247 DOI: 10.3390/biom9010001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 12/15/2018] [Accepted: 12/17/2018] [Indexed: 12/14/2022] Open
Abstract
Proper regulation of microtubules (MTs) is critical for the execution of diverse cellular processes, including mitotic spindle assembly and chromosome segregation. There are a multitude of cellular factors that regulate the dynamicity of MTs and play critical roles in mitosis. Members of the Kinesin-8 family of motor proteins act as MT-destabilizing factors to control MT length in a spatially and temporally regulated manner. In this review, we focus on recent advances in our understanding of the structure and function of the Kinesin-8 motor domain, and the emerging contributions of the C-terminal tail of Kinesin-8 proteins to regulate motor activity and localization.
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Affiliation(s)
- Sanjay Shrestha
- Medical Sciences Program, Indiana University, Bloomington, IN 47405, USA.
| | - Mark Hazelbaker
- Medical Sciences Program, Indiana University, Bloomington, IN 47405, USA.
| | - Amber L Yount
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA.
| | - Claire E Walczak
- Medical Sciences Program, Indiana University, Bloomington, IN 47405, USA.
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24
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Bouvrais H, Chesneau L, Pastezeur S, Fairbrass D, Delattre M, Pécréaux J. Microtubule Feedback and LET-99-Dependent Control of Pulling Forces Ensure Robust Spindle Position. Biophys J 2018; 115:2189-2205. [PMID: 30447992 PMCID: PMC6289040 DOI: 10.1016/j.bpj.2018.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 10/03/2018] [Accepted: 10/09/2018] [Indexed: 11/26/2022] Open
Abstract
During asymmetric division of the Caenorhabditis elegans zygote, to properly distribute cell fate determinants, the mitotic spindle is asymmetrically localized by a combination of centering and cortical-pulling microtubule-mediated forces, the dynamics of the latter being regulated by mitotic progression. Here, we show a, to our knowledge, novel and additional regulation of these forces by spindle position itself. For that, we observed the onset of transverse spindle oscillations, which reflects the burst of anaphase pulling forces. After delaying anaphase onset, we found that the position at which the spindle starts to oscillate was unchanged compared to control embryos and uncorrelated to anaphase onset. In mapping the cortical microtubule dynamics, we measured a steep increase in microtubule contact density after the posterior centrosome reached the critical position of 70% of embryo length, strongly suggesting the presence of a positional switch for spindle oscillations. Expanding a previous model based on a force-generator temporal control, we implemented this positional switch and observed that the large increase in microtubule density accounted for the pulling force burst. Thus, we propose that the spindle position influences the cortical availability of microtubules on which the active force generators, controlled by cell cycle progression, can pull. Importantly, we found that this positional control relies on the polarity-dependent LET-99 cortical band, the boundary of which could be probed by microtubules. This dual positional and temporal control well accounted for our observation that the oscillation onset position resists changes in cellular geometry and moderate variations in the active force generator number. Finally, our model suggests that spindle position at mitosis end is more sensitive to the polarity factor LET-99, which restricts the region of active force generators to a posterior-most region, than to microtubule number or force generator number/activity. Overall, we show that robustness in spindle positioning originates in cell mechanics rather than biochemical networks.
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Affiliation(s)
| | | | | | | | - Marie Delattre
- Univ Lyon, ENS de Lyon, Univ Claude Bernard, Laboratory of Biology and Modelling of the Cell, Lyon University, Lyon, France
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25
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Feng M, Dang N, Bai Y, Wei H, Meng L, Wang K, Zhao Z, Chen Y, Gao F, Chen Z, Li L, Zhang S. Differential expression profiles of long non‑coding RNAs during the mouse pronuclear stage under normal gravity and simulated microgravity. Mol Med Rep 2018; 19:155-164. [PMID: 30483791 PMCID: PMC6297735 DOI: 10.3892/mmr.2018.9675] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 10/19/2018] [Indexed: 01/22/2023] Open
Abstract
Pronuclear migration, which is the initial stage of embryonic development and the marker of zygote formation, is a crucial process during mammalian preimplantation embryonic development. Recent studies have revealed that long non-coding RNAs (lncRNAs) serve an important role in early embryonic development. However, the functional regulation of lncRNAs in this process has yet to be elucidated, largely due to the difficulty of assessing gene expression alterations during the very short time in which pronuclear migration occurs. It has previously been reported that migration of the pronucleus of a zygote can be obstructed by simulated microgravity. To investigate pronuclear migration in mice, a rotary cell culture system was employed, which generates simulated microgravity, in order to interfere with murine pronuclear migration. Subsequently, lncRNA sequencing was performed to investigate the mechanism underlying this process. In the present study, a comprehensive analysis of lncRNA profile during the mouse pronuclear stage was conducted, in which 3,307 lncRNAs were identified based on single-cell RNA sequencing data. Furthermore, 52 lncRNAs were identified that were significantly differentially expressed. Subsequently, 10 lncRNAs were selected for validation by reverse transcription-quantitative polymerase chain reaction, in which the same relative expression pattern was observed. The results revealed that 12 lncRNAs (lnc006745, lnc007956, lnc013100, lnc013782, lnc017097, lnc019869, lnc025838, lnc027046, lnc005454, lnc007956, lnc019410 and lnc019607), with tubulin β 4B class IVb or actinin α 4 as target genes, may be associated with the expression of microtubule and microfilament proteins. Binding association was confirmed using a dual-luciferase reporter assay. Finally, Gene Ontology analysis revealed that the target genes of the differentially expressed lncRNAs participated in cellular processes associated with protein transport, binding, catalytic activity, membrane-bounded organelle, protein complex and the cortical cytoskeleton. These findings suggested that these lncRNAs may be associated with migration of the mouse pronucleus.
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Affiliation(s)
- Meiying Feng
- College of Animal Science, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Lab of Agro‑Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, P.R. China
| | - Nannan Dang
- College of Animal Science, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Lab of Agro‑Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, P.R. China
| | - Yinshan Bai
- College of Animal Science, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Lab of Agro‑Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, P.R. China
| | - Hengxi Wei
- College of Animal Science, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Lab of Agro‑Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, P.R. China
| | - Li Meng
- College of Animal Science, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Lab of Agro‑Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, P.R. China
| | - Kai Wang
- College of Animal Science, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Lab of Agro‑Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, P.R. China
| | - Zhihong Zhao
- College of Animal Science, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Lab of Agro‑Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, P.R. China
| | - Yun Chen
- College of Animal Science, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Lab of Agro‑Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, P.R. China
| | - Fenglei Gao
- College of Animal Science, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Lab of Agro‑Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, P.R. China
| | - Zhilin Chen
- College of Animal Science, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Lab of Agro‑Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, P.R. China
| | - Li Li
- College of Animal Science, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Lab of Agro‑Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, P.R. China
| | - Shouquan Zhang
- College of Animal Science, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Lab of Agro‑Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, P.R. China
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26
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Tanimoto H, Sallé J, Dodin L, Minc N. Physical Forces Determining the Persistency and Centering Precision of Microtubule Asters. NATURE PHYSICS 2018; 14:848-854. [PMID: 30079097 PMCID: PMC6071857 DOI: 10.1038/s41567-018-0154-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 04/24/2018] [Indexed: 05/24/2023]
Abstract
In early embryos, microtubules form star-shaped aster structures that can measure up to hundreds of micrometres, and move at high speeds to find the geometrical centre of the cell. This process, known as aster centration, is essential for the fidelity of cell division and development, but how cells succeed in moving these large structures through their crowded and fluctuating cytoplasm remains unclear. Here, we demonstrate that the positional fluctuations of migrating sea urchin sperm asters are small, anisotropic, and associated with the stochasticity of dynein-dependent forces moving the aster. Using in vivo magnetic tweezers to directly measure aster forces inside cells, we derive a linear aster force-velocity relationship and provide evidence for a spring-like active mechanism stabilizing the transverse position of the asters. The large frictional coefficient and spring constant quantitatively account for the amplitude and growth characteristics of athermal positional fluctuations, demonstrating that aster mechanics ensure noise suppression to promote persistent and precise centration. These findings define generic biophysical regimes of active cytoskeletal mechanics underlying the accuracy of cell division and early embryonic development.
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Affiliation(s)
- Hirokazu Tanimoto
- Institut Jacques Monod, CNRS UMR7592 and Université Paris Diderot, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
| | - Jeremy Sallé
- Institut Jacques Monod, CNRS UMR7592 and Université Paris Diderot, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
| | - Louise Dodin
- Institut Jacques Monod, CNRS UMR7592 and Université Paris Diderot, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
| | - Nicolas Minc
- Institut Jacques Monod, CNRS UMR7592 and Université Paris Diderot, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
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27
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Eno C, Pelegri F. Modulation of F-actin dynamics by maternal Mid1ip1L controls germ plasm aggregation and furrow recruitment in the zebrafish embryo. Development 2018; 145:dev156596. [PMID: 29724756 PMCID: PMC6001372 DOI: 10.1242/dev.156596] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 04/23/2018] [Indexed: 12/11/2022]
Abstract
During the early embryonic cell cycles, zebrafish germ plasm ribonucleoparticles (RNPs) gradually multimerize and become recruited to the forming furrows. RNPs multimerization occurs prior to and during furrow initiation, as forming aggregates move outward through their association with the tips of growing interphase astral microtubules. Germ plasm RNPs are also associated with short cortical F-actin. We show that, in embryos mutant for the cytoskeletal regulator mid1ip1l, germ plasm RNPs fail to become recruited to the furrow, accumulating instead at the periphery of the blastodisc. RNP aggregates are associated with zones of mid1ip1l-dependent cyclical local cortical F-actin network enrichments, as well as contractions at both the cortex and the contractile ring. F-actin inhibition in wild-type embryos mimics the RNP peripheral accumulation defect of mid1ip1l mutants. Our studies suggest that a common mechanism underlies distinct steps of germ plasm RNP segregation. At the cortex, this process attenuates microtubule-dependent outward RNP movement to retain RNPs in the blastodisc cortex and allow their recruitment to the furrows. F-actin network contraction likely also facilitates higher-order germ plasm RNP multimerization.
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Affiliation(s)
- Celeste Eno
- Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, USA
| | - Francisco Pelegri
- Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, USA
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28
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Haupt A, Minc N. How cells sense their own shape - mechanisms to probe cell geometry and their implications in cellular organization and function. J Cell Sci 2018; 131:131/6/jcs214015. [PMID: 29581183 DOI: 10.1242/jcs.214015] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cells come in a variety of shapes that most often underlie their functions. Regulation of cell morphogenesis implies that there are mechanisms for shape sensing that still remain poorly appreciated. Global and local cell geometry features, such as aspect ratio, size or membrane curvature, may be probed by intracellular modules, such as the cytoskeleton, reaction-diffusion systems or molecular complexes. In multicellular tissues, cell shape emerges as an important means to transduce tissue-inherent chemical and mechanical cues into intracellular organization. One emergent paradigm is that cell-shape sensing is most often based upon mechanisms of self-organization, rather than determinism. Here, we review relevant work that has elucidated some of the core principles of how cellular geometry may be conveyed into spatial information to guide processes, such as polarity, signaling, morphogenesis and division-plane positioning.
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Affiliation(s)
- Armin Haupt
- Institut Jacques Monod, CNRS UMR7592 and Université Paris Diderot, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
| | - Nicolas Minc
- Institut Jacques Monod, CNRS UMR7592 and Université Paris Diderot, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
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29
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Howard J, Garzon-Coral C. Physical Limits on the Precision of Mitotic Spindle Positioning by Microtubule Pushing forces: Mechanics of mitotic spindle positioning. Bioessays 2017; 39:10.1002/bies.201700122. [PMID: 28960439 PMCID: PMC5698852 DOI: 10.1002/bies.201700122] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 08/13/2017] [Indexed: 01/07/2023]
Abstract
Tissues are shaped and patterned by mechanical and chemical processes. A key mechanical process is the positioning of the mitotic spindle, which determines the size and location of the daughter cells within the tissue. Recent force and position-fluctuation measurements indicate that pushing forces, mediated by the polymerization of astral microtubules against- the cell cortex, maintain the mitotic spindle at the cell center in Caenorhabditis elegans embryos. The magnitude of the centering forces suggests that the physical limit on the accuracy and precision of this centering mechanism is determined by the number of pushing microtubules rather than by thermally driven fluctuations. In cells that divide asymmetrically, anti-centering, pulling forces generated by cortically located dyneins, in conjunction with microtubule depolymerization, oppose the pushing forces to drive spindle displacements away from the center. Thus, a balance of centering pushing forces and anti-centering pulling forces localize the mitotic spindles within dividing C. elegans cells.
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Affiliation(s)
- Jonathon Howard
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Carlos Garzon-Coral
- Shriram Center for Chemical Engineering & Bioengineering, Stanford University, CA 94305, USA
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30
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Zhao ZL, Liu ZY, Du J, Xu GK, Feng XQ. A Dynamic Biochemomechanical Model of Geometry-Confined Cell Spreading. Biophys J 2017; 112:2377-2386. [PMID: 28591610 DOI: 10.1016/j.bpj.2017.04.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 04/11/2017] [Accepted: 04/13/2017] [Indexed: 01/09/2023] Open
Abstract
Cell spreading is involved in many physiological and pathological processes. The spreading behavior of a cell significantly depends on its microenvironment, but the biochemomechanical mechanisms of geometry-confined cell spreading remain unclear. A dynamic model is here established to investigate the spreading of cells confined in a finite region with different geometries, e.g., rectangle, ellipse, triangle, and L-shape. This model incorporates both biophysical and biochemical mechanisms, including actin polymerization, integrin-mediated binding, plasma viscoelasticity, and the elasticity of membranes and microtubules. We simulate the dynamic configurational evolution of a cell under different geometric microenvironments, including the angular distribution of microtubule forces and the deformation of the nucleus. The results indicate that the positioning of the cell-division plane is affected by its boundary confinement: a cell divides in a plane perpendicular to its minimal principal axis of inertia of area. In addition, the effects of such physical factors as the adhesive bond density, membrane tension, and microtubule number are examined on the cell spreading dynamics. The theoretical predictions show a good agreement with relevant experimental results. This work sheds light on the geometry-confined spreading dynamics of cells and holds potential applications in regulating cell division and designing cell-based sensors.
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Affiliation(s)
- Zi-Long Zhao
- AML, Department of Engineering Mechanics, Institute of Biomechanics and Medical Engineering, Tsinghua University, Beijing, China; Center for Nano and Micro Mechanics, Tsinghua University, Beijing, China
| | - Zong-Yuan Liu
- AML, Department of Engineering Mechanics, Institute of Biomechanics and Medical Engineering, Tsinghua University, Beijing, China; Center for Nano and Micro Mechanics, Tsinghua University, Beijing, China
| | - Jing Du
- AML, Department of Engineering Mechanics, Institute of Biomechanics and Medical Engineering, Tsinghua University, Beijing, China
| | - Guang-Kui Xu
- International Center for Applied Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an Jiaotong University, Xi'an, China
| | - Xi-Qiao Feng
- AML, Department of Engineering Mechanics, Institute of Biomechanics and Medical Engineering, Tsinghua University, Beijing, China; Center for Nano and Micro Mechanics, Tsinghua University, Beijing, China.
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31
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Ohnishi Y, Okamoto T. Nuclear migration during karyogamy in rice zygotes is mediated by continuous convergence of actin meshwork toward the egg nucleus. JOURNAL OF PLANT RESEARCH 2017; 130:339-348. [PMID: 27995374 DOI: 10.1007/s10265-016-0892-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 08/10/2016] [Indexed: 05/20/2023]
Abstract
Fertilization is comprised of two sequential fusion processes; plasmogamy and karyogamy. Karyogamy completes with migration and fusion of the male and female nuclei in the fused cell. In animals, microtubules organized by the centrosome control female/male pronuclei migration. In contrast, the nuclear migration in fused gametes of angiosperms is controlled by actin filaments, but the mechanism that regulates actin filament-dependent nuclear migration is not clear. In this study, we prepared fused rice (Oryza sativa L.) gametes/zygotes using in vitro fertilization and observed the spatial and temporal movements of actin filaments and sperm nuclei. Our results show that actin filaments in egg cells form a meshwork structure surrounding the nuclei. Quantitative analysis of the actin meshwork dynamics suggests that actin meshwork converges toward the egg nucleus. In egg cells fused with sperm cells, actin filaments appeared to interact with a portion of the sperm nuclear membrane. The velocity of the actin filaments was positively correlated with the velocity of the sperm nucleus during karyogamy. These results suggest that sperm nuclear membrane and actin filaments physically interact with each other during karyogamy, and that the sperm nucleus migrates toward the egg nucleus through the convergence of the actin meshwork. Interestingly, actin filament velocity increased promptly after gamete fusion and was further elevated during nuclear fusion. In addition to the migration of gamete nuclei, convergence of actin meshwork may also be critical during early zygotic developments.
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Affiliation(s)
- Yukinosuke Ohnishi
- Department of Biological Sciences, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji, Tokyo, 192-0397, Japan.
| | - Takashi Okamoto
- Department of Biological Sciences, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji, Tokyo, 192-0397, Japan
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32
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Hasley A, Chavez S, Danilchik M, Wühr M, Pelegri F. Vertebrate Embryonic Cleavage Pattern Determination. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 953:117-171. [PMID: 27975272 PMCID: PMC6500441 DOI: 10.1007/978-3-319-46095-6_4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The pattern of the earliest cell divisions in a vertebrate embryo lays the groundwork for later developmental events such as gastrulation, organogenesis, and overall body plan establishment. Understanding these early cleavage patterns and the mechanisms that create them is thus crucial for the study of vertebrate development. This chapter describes the early cleavage stages for species representing ray-finned fish, amphibians, birds, reptiles, mammals, and proto-vertebrate ascidians and summarizes current understanding of the mechanisms that govern these patterns. The nearly universal influence of cell shape on orientation and positioning of spindles and cleavage furrows and the mechanisms that mediate this influence are discussed. We discuss in particular models of aster and spindle centering and orientation in large embryonic blastomeres that rely on asymmetric internal pulling forces generated by the cleavage furrow for the previous cell cycle. Also explored are mechanisms that integrate cell division given the limited supply of cellular building blocks in the egg and several-fold changes of cell size during early development, as well as cytoskeletal specializations specific to early blastomeres including processes leading to blastomere cohesion. Finally, we discuss evolutionary conclusions beginning to emerge from the contemporary analysis of the phylogenetic distributions of cleavage patterns. In sum, this chapter seeks to summarize our current understanding of vertebrate early embryonic cleavage patterns and their control and evolution.
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Affiliation(s)
- Andrew Hasley
- Laboratory of Genetics, University of Wisconsin-Madison, Genetics/Biotech Addition, Room 2424, 425-G Henry Mall, Madison, WI, 53706, USA
| | - Shawn Chavez
- Division of Reproductive & Developmental Sciences, Oregon National Primate Research Center, Department of Physiology & Pharmacology, Oregon Heath & Science University, 505 NW 185th Avenue, Beaverton, OR, 97006, USA
- Division of Reproductive & Developmental Sciences, Oregon National Primate Research Center, Department of Obstetrics & Gynecology, Oregon Heath & Science University, 505 NW 185th Avenue, Beaverton, OR, 97006, USA
| | - Michael Danilchik
- Department of Integrative Biosciences, L499, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA
| | - Martin Wühr
- Department of Molecular Biology & The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Icahn Laboratory, Washington Road, Princeton, NJ, 08544, USA
| | - Francisco Pelegri
- Laboratory of Genetics, University of Wisconsin-Madison, Genetics/Biotech Addition, Room 2424, 425-G Henry Mall, Madison, WI, 53706, USA.
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33
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Tassan JP, Wühr M, Hatte G, Kubiak J. Asymmetries in Cell Division, Cell Size, and Furrowing in the Xenopus laevis Embryo. Results Probl Cell Differ 2017; 61:243-260. [PMID: 28409308 DOI: 10.1007/978-3-319-53150-2_11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Asymmetric cell divisions produce two daughter cells with distinct fate. During embryogenesis, this mechanism is fundamental to build tissues and organs because it generates cell diversity. In adults, it remains crucial to maintain stem cells. The enthusiasm for asymmetric cell division is not only motivated by the beauty of the mechanism and the fundamental questions it raises, but has also very pragmatic reasons. Indeed, misregulation of asymmetric cell divisions is believed to have dramatic consequences potentially leading to pathogenesis such as cancers. In diverse model organisms, asymmetric cell divisions result in two daughter cells, which differ not only by their fate but also in size. This is the case for the early Xenopus laevis embryo, in which the two first embryonic divisions are perpendicular to each other and generate two pairs of blastomeres, which usually differ in size: one pair of blastomeres is smaller than the other. Small blastomeres will produce embryonic dorsal structures, whereas the larger pair will evolve into ventral structures. Here, we present a speculative model on the origin of the asymmetry of this cell division in the Xenopus embryo. We also discuss the apparently coincident asymmetric distribution of cell fate determinants and cell-size asymmetry of the 4-cell stage embryo. Finally, we discuss the asymmetric furrowing during epithelial cell cytokinesis occurring later during Xenopus laevis embryo development.
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Affiliation(s)
- Jean-Pierre Tassan
- , CNRS UMR 6290, Rennes, France. .,Université de Rennes 1, Institut de Génétique et Développement de Rennes, Rennes, France.
| | - Martin Wühr
- Department of Molecular Biology and the Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Guillaume Hatte
- , CNRS UMR 6290, Rennes, France.,Université de Rennes 1, Institut de Génétique et Développement de Rennes, Rennes, France
| | - Jacek Kubiak
- , CNRS UMR 6290, Rennes, France.,Université de Rennes 1, Institut de Génétique et Développement de Rennes, Rennes, France
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34
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Wu HY, Nazockdast E, Shelley MJ, Needleman DJ. Forces positioning the mitotic spindle: Theories, and now experiments. Bioessays 2016; 39. [PMID: 28026040 DOI: 10.1002/bies.201600212] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The position of the spindle determines the position of the cleavage plane, and is thus crucial for cell division. Although spindle positioning has been extensively studied, the underlying forces ultimately responsible for moving the spindle remain poorly understood. A recent pioneering study by Garzon-Coral et al. uses magnetic tweezers to perform the first direct measurements of the forces involved in positioning the mitotic spindle. Combining this with molecular perturbations and geometrical effects, they use their data to argue that the forces that keep the spindle in its proper position for cell division arise from astral microtubules growing and pushing against the cell's cortex. Here, we review these ground-breaking experiments, the various biomechanical models for spindle positioning that they seek to differentiate, and discuss new questions raised by these measurements.
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Affiliation(s)
- Hai-Yin Wu
- Department of Physics, Harvard University, Cambridge, MA, USA
- Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, MA, USA
| | - Ehssan Nazockdast
- Center for Computational Biology, Simons Foundation, New York, NY, USA
| | - Michael J Shelley
- Center for Computational Biology, Simons Foundation, New York, NY, USA
- Courant Institute of Mathematical Sciences, New York University, New York, NY, USA
| | - Daniel J Needleman
- Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
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35
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He L, Chen W, Wu PH, Jimenez A, Wong BS, San A, Konstantopoulos K, Wirtz D. Local 3D matrix confinement determines division axis through cell shape. Oncotarget 2016; 7:6994-7011. [PMID: 26515603 PMCID: PMC4872764 DOI: 10.18632/oncotarget.5848] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 10/03/2015] [Indexed: 12/24/2022] Open
Abstract
How the division axis is determined in mammalian cells embedded in three-dimensional (3D) matrices remains elusive, despite that many types of cells divide in 3D environments. Cells on two-dimensional (2D) substrates typically round up completely to divide. Here, we show that in 3D collagen matrices, mammalian cells such as HT1080 human fibrosarcoma and MDA-MB-231 breast cancer cells exhibit division modes distinct from their Counterparts on 2D substrates, with a markedly higher fraction of cells remaining highly elongated through mitosis in 3D matrices. The long axis of elongated mitotic cells accurately predicts the division axis, independently of matrix density and cell-matrix interactions. This 3D-specific elongated division mode is determined by the local confinement produced by the matrix and the ability of cells to protrude and locally remodel the matrix via β1 integrin. Elongated division is readily recapitulated using collagen-coated microfabricated channels. Cells depleted of β1 integrin still divide in the elongated mode in microchannels, suggesting that 3D confinement is sufficient to induce the elongated cell-division phenotype.
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Affiliation(s)
- Lijuan He
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.,Johns Hopkins Physical Sciences - Oncology Center, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Weitong Chen
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Pei-Hsun Wu
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.,Johns Hopkins Physical Sciences - Oncology Center, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Angela Jimenez
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.,Johns Hopkins Physical Sciences - Oncology Center, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Bin Sheng Wong
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.,Johns Hopkins Physical Sciences - Oncology Center, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Angela San
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Konstantinos Konstantopoulos
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.,Johns Hopkins Physical Sciences - Oncology Center, The Johns Hopkins University, Baltimore, Maryland 21218, USA.,Departments of Oncology and Pathology and Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Denis Wirtz
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.,Johns Hopkins Physical Sciences - Oncology Center, The Johns Hopkins University, Baltimore, Maryland 21218, USA.,Departments of Oncology and Pathology and Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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36
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Pierre A, Sallé J, Wühr M, Minc N. Generic Theoretical Models to Predict Division Patterns of Cleaving Embryos. Dev Cell 2016; 39:667-682. [PMID: 27997824 PMCID: PMC5180451 DOI: 10.1016/j.devcel.2016.11.018] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 10/06/2016] [Accepted: 11/21/2016] [Indexed: 12/18/2022]
Abstract
Life for all animals starts with a precise 3D choreography of reductive divisions of the fertilized egg, known as cleavage patterns. These patterns exhibit conserved geometrical features and striking interspecies invariance within certain animal classes. To identify the generic rules that may govern these morphogenetic events, we developed a 3D-modeling framework that iteratively infers blastomere division positions and orientations, and consequent multicellular arrangements. From a minimal set of parameters, our model predicts detailed features of cleavage patterns in the embryos of fishes, amphibians, echinoderms, and ascidians, as well as the genetic and physical perturbations that alter these patterns. This framework demonstrates that a geometrical system based on length-dependent microtubule forces that probe blastomere shape and yolk gradients, biased by cortical polarity domains, may dictate division patterns and overall embryo morphogenesis. These studies thus unravel the default self-organization rules governing early embryogenesis and how they are altered by deterministic regulatory layers.
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Affiliation(s)
- Anaëlle Pierre
- CNRS UMR 7592, Institut Jacques Monod, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
| | - Jérémy Sallé
- CNRS UMR 7592, Institut Jacques Monod, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
| | - Martin Wühr
- Department of Molecular Biology, Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Nicolas Minc
- CNRS UMR 7592, Institut Jacques Monod, 15 rue Hélène Brion, 75205 Paris Cedex 13, France.
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37
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Kawamura R, Uehara D, Kobayashi N, Nakabayashi S, Yoshikawa HY. Kinesin-Driven Active Substrate Giving Stochastic Mechanical Stimuli to Cells for Characterization. ACS Biomater Sci Eng 2016; 2:2333-2338. [PMID: 33465881 DOI: 10.1021/acsbiomaterials.6b00538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present a new platform to give stochastic mechanical stimuli to cells for their characterization. There nano- and micrometer scaled fluctuations are generated by an engineered motor protein system of kinesin-microtubules (MTs) on a solid surface. Cells have abilities to deform in many ways during homeostatic metabolism, tissue forming processes, cancer developments, and so on. Namely, cells in biological tissues are exposed to noise-like stochastic movements at nano- and micrometer-scales, which mainly come from the mechanical environment surrounding the cells. Although cells seem to have the potential to respond to such types of mechanical stimuli, the influences on cellular behaviors are poorly understood. As a first attempt to verify an effect of noise-like mechanical stimuli in vitro, we prepared a system to give stochastic mechanical stimuli to cells using a technique of in vitro motility assay for a kinesin-MT system. An active substrate was obtained by integrating movements of MTs on a kinesin-coated glass surface via cross-linkage, and stochastic mechanical stimuli at the cell-scale were successfully applied to the seeded cells. There, traveling distances of the cells over one cell length were observed until they started to adhere. When metastatic melanoma cells were exposed to the stochastic mechanical stimuli, unusually long protrusions or extensions of cell bodies were observed. Cellular aggregations were also promoted through the movements on this active substrate which could disturb the landing and enhance the collisions of the cells. This approach giving mechanical stimuli to cells in a stochastic manner at nano- and micrometer-scales might allow us to uncover unknown behaviors of cells, which might contribute to research fields requiring our understanding on the mechanical nature of cells, such as cancer diagnosis and regenerative medicine.
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Affiliation(s)
- Ryuzo Kawamura
- Department of Chemistry, Saitama University, 255 Shimo-okubo, Saitama 338-8570, Japan
| | - Daiki Uehara
- Department of Chemistry, Saitama University, 255 Shimo-okubo, Saitama 338-8570, Japan
| | - Naritaka Kobayashi
- Division of Strategic Research and Development, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Saitama 338-8570, Japan
| | - Seiichiro Nakabayashi
- Department of Chemistry, Saitama University, 255 Shimo-okubo, Saitama 338-8570, Japan.,Division of Strategic Research and Development, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Saitama 338-8570, Japan
| | - Hiroshi Y Yoshikawa
- Department of Chemistry, Saitama University, 255 Shimo-okubo, Saitama 338-8570, Japan.,Division of Strategic Research and Development, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Saitama 338-8570, Japan
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38
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Ishihara K, Korolev KS, Mitchison TJ. Physical basis of large microtubule aster growth. eLife 2016; 5. [PMID: 27892852 PMCID: PMC5207775 DOI: 10.7554/elife.19145] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 11/21/2016] [Indexed: 12/24/2022] Open
Abstract
Microtubule asters - radial arrays of microtubules organized by centrosomes - play a fundamental role in the spatial coordination of animal cells. The standard model of aster growth assumes a fixed number of microtubules originating from the centrosomes. However, aster morphology in this model does not scale with cell size, and we recently found evidence for non-centrosomal microtubule nucleation. Here, we combine autocatalytic nucleation and polymerization dynamics to develop a biophysical model of aster growth. Our model predicts that asters expand as traveling waves and recapitulates all major aspects of aster growth. With increasing nucleation rate, the model predicts an explosive transition from stationary to growing asters with a discontinuous jump of the aster velocity to a nonzero value. Experiments in frog egg extract confirm the main theoretical predictions. Our results suggest that asters observed in large fish and amphibian eggs are a meshwork of short, unstable microtubules maintained by autocatalytic nucleation and provide a paradigm for the assembly of robust and evolvable polymer networks. DOI:http://dx.doi.org/10.7554/eLife.19145.001 Cells must carefully organize their contents in order to work effectively. Protein filaments called microtubules often play important roles in this organization, as well as giving structure to the cell. Many cells contain structures called asters that are formed of microtubules that radiate out from a central point (much like a star shape). Textbooks generally state that all microtubules in the aster grow outward from its center. If this was the case, the microtubules at the edge of large asters – such as those found in frog egg cells and other extremely large cells – would be spread relatively far apart from each other. However, even at the edges of large asters, the microtubules are quite densely packed. In 2014, a group of researchers proposed that new microtubules could form throughout the aster instead of all originating from the center. This model had not been tested; it was also unclear under what conditions an aster would be able to grow to fill a large cell. Ishihara et al. – including some of the researchers involved in the 2014 work – have now developed a mathematical theory of aster growth that is based on the assumption that microtubules stimulate the generation of new microtubules. The theory reproduces the key features seen during the growth of asters in large cells, and predicts that the asters may stay at a constant size or grow continuously. The condition required for the aster to grow is simple: each microtubule in it has to trigger the generation of at least one new microtubule during its lifetime. Ishihara et al. have named this process “collective growth”. Experiments performed using microtubules taken from crushed frog eggs and assembled under a cover slip provided further evidence that asters grow via a collective growth process. Future studies could now investigate whether collective growth also underlies the formation of other cellular structures. DOI:http://dx.doi.org/10.7554/eLife.19145.002
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Affiliation(s)
- Keisuke Ishihara
- Department of Systems Biology, Harvard Medical School, Boston, United States.,Cell Division Group, Marine Biological Laboratory, Woods Hole, United Sates
| | - Kirill S Korolev
- Department of Physics and Graduate Program in Bioinformatics, Boston University, Boston, United States
| | - Timothy J Mitchison
- Department of Systems Biology, Harvard Medical School, Boston, United States.,Cell Division Group, Marine Biological Laboratory, Woods Hole, United Sates
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Pécréaux J, Redemann S, Alayan Z, Mercat B, Pastezeur S, Garzon-Coral C, Hyman AA, Howard J. The Mitotic Spindle in the One-Cell C. elegans Embryo Is Positioned with High Precision and Stability. Biophys J 2016; 111:1773-1784. [PMID: 27760363 PMCID: PMC5071606 DOI: 10.1016/j.bpj.2016.09.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 09/05/2016] [Accepted: 09/07/2016] [Indexed: 01/20/2023] Open
Abstract
Precise positioning of the mitotic spindle is important for specifying the plane of cell division, which in turn determines how the cytoplasmic contents of the mother cell are partitioned into the daughter cells, and how the daughters are positioned within the tissue. During metaphase in the early Caenorhabditis elegans embryo, the spindle is aligned and centered on the anterior-posterior axis by a microtubule-dependent machinery that exerts restoring forces when the spindle is displaced from the center. To investigate the accuracy and stability of centering, we tracked the position and orientation of the mitotic spindle during the first cell division with high temporal and spatial resolution. We found that the precision is remarkably high: the cell-to-cell variation in the transverse position of the center of the spindle during metaphase, as measured by the standard deviation, was only 1.5% of the length of the short axis of the cell. Spindle position is also very stable: the standard deviation of the fluctuations in transverse spindle position during metaphase was only 0.5% of the short axis of the cell. Assuming that stability is limited by fluctuations in the number of independent motor elements such as microtubules or dyneins underlying the centering machinery, we infer that the number is ∼1000, consistent with the several thousand of astral microtubules in these cells. Astral microtubules grow out from the two spindle poles, make contact with the cell cortex, and then shrink back shortly thereafter. The high stability of centering can be accounted for quantitatively if, while making contact with the cortex, the astral microtubules buckle as they exert compressive, pushing forces. We thus propose that the large number of microtubules in the asters provides a highly precise mechanism for positioning the spindle during metaphase while assembly is completed before the onset of anaphase.
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Affiliation(s)
- Jacques Pécréaux
- Institute of Genetics and Development of Rennes, Unité Mixte de Recherche 6290, Centre National de la Recherche Scientifique, CS 34317, Rennes, France; Institute of Genetics and Development of Rennes, University Rennes 1, Rennes, France; Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
| | - Stefanie Redemann
- Dresden University of Technology, Dresden, Germany; Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Zahraa Alayan
- Institute of Genetics and Development of Rennes, Unité Mixte de Recherche 6290, Centre National de la Recherche Scientifique, CS 34317, Rennes, France; Institute of Genetics and Development of Rennes, University Rennes 1, Rennes, France
| | - Benjamin Mercat
- Institute of Genetics and Development of Rennes, Unité Mixte de Recherche 6290, Centre National de la Recherche Scientifique, CS 34317, Rennes, France; Institute of Genetics and Development of Rennes, University Rennes 1, Rennes, France
| | - Sylvain Pastezeur
- Institute of Genetics and Development of Rennes, Unité Mixte de Recherche 6290, Centre National de la Recherche Scientifique, CS 34317, Rennes, France; Institute of Genetics and Development of Rennes, University Rennes 1, Rennes, France
| | - Carlos Garzon-Coral
- Shriram Center of Bioengineering and Chemical Engineering, Stanford University, Stanford, California; Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Anthony A Hyman
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Jonathon Howard
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany; Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, Connecticut.
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40
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Khetan N, Athale CA. A Motor-Gradient and Clustering Model of the Centripetal Motility of MTOCs in Meiosis I of Mouse Oocytes. PLoS Comput Biol 2016; 12:e1005102. [PMID: 27706163 PMCID: PMC5051731 DOI: 10.1371/journal.pcbi.1005102] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 08/11/2016] [Indexed: 12/31/2022] Open
Abstract
Asters nucleated by Microtubule (MT) organizing centers (MTOCs) converge on chromosomes during spindle assembly in mouse oocytes undergoing meiosis I. Time-lapse imaging suggests that this centripetal motion is driven by a biased 'search-and-capture' mechanism. Here, we develop a model of a random walk in a drift field to test the nature of the bias and the spatio-temporal dynamics of the search process. The model is used to optimize the spatial field of drift in simulations, by comparison to experimental motility statistics. In a second step, this optimized gradient is used to determine the location of immobilized dynein motors and MT polymerization parameters, since these are hypothesized to generate the gradient of forces needed to move MTOCs. We compare these scenarios to self-organized mechanisms by which asters have been hypothesized to find the cell-center- MT pushing at the cell-boundary and clustering motor complexes. By minimizing the error between simulation outputs and experiments, we find a model of "pulling" by a gradient of dynein motors alone can drive the centripetal motility. Interestingly, models of passive MT based "pushing" at the cortex, clustering by cross-linking motors and MT-dynamic instability gradients alone, by themselves do not result in the observed motility. The model predicts the sensitivity of the results to motor density and stall force, but not MTs per aster. A hybrid model combining a chromatin-centered immobilized dynein gradient, diffusible minus-end directed clustering motors and pushing at the cell cortex, is required to comprehensively explain the available data. The model makes experimentally testable predictions of a spatial bias and self-organized mechanisms by which MT asters can find the center of a large cell.
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Affiliation(s)
- Neha Khetan
- Division of Biology, Indian Institute of Science Education and Research (IISER) Pune, Pune, Maharashtra, India
| | - Chaitanya A. Athale
- Division of Biology, Indian Institute of Science Education and Research (IISER) Pune, Pune, Maharashtra, India
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Milunović-Jevtić A, Mooney P, Sulerud T, Bisht J, Gatlin JC. Centrosomal clustering contributes to chromosomal instability and cancer. Curr Opin Biotechnol 2016; 40:113-118. [PMID: 27046071 DOI: 10.1016/j.copbio.2016.03.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/07/2016] [Accepted: 03/15/2016] [Indexed: 12/18/2022]
Abstract
Cells assemble mitotic spindles during each round of division to insure accurate segregation of their duplicated genome. In animal cells, stereotypical spindles have two poles, each containing one centrosome, from which microtubules are nucleated. By contrast, many cancer cells often contain more than two centrosomes and form transient multipolar spindle structures with more than two poles. In order to divide and produce viable progeny, the multipolar spindle intermediate must be reshaped into a pseudo-bipolar structure via a process called centrosomal clustering. Pseudo-bipolar spindles appear to function normally during mitosis, but they occasionally give rise to aneuploid and transformed daughter cells. Agents that inhibit centrosomal clustering might therefore work as a potential cancer therapy, specifically targeting mitosis in supernumerary centrosome-containing cells.
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Affiliation(s)
| | - P Mooney
- University of Wyoming, Department of Molecular Biology, United States
| | - T Sulerud
- University of Wyoming, Department of Molecular Biology, United States
| | - J Bisht
- University of Wyoming, Department of Molecular Biology, United States
| | - J C Gatlin
- University of Wyoming, Department of Molecular Biology, United States.
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Tanimoto H, Kimura A, Minc N. Shape-motion relationships of centering microtubule asters. J Cell Biol 2016; 212:777-87. [PMID: 27022090 PMCID: PMC4810306 DOI: 10.1083/jcb.201510064] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 02/17/2016] [Indexed: 11/22/2022] Open
Abstract
Although mechanisms that contribute to microtubule (MT) aster positioning have been extensively studied, still little is known on how asters move inside cells to faithfully target a cellular location. Here, we study sperm aster centration in sea urchin eggs, as a stereotypical large-scale aster movement with extreme constraints on centering speed and precision. By tracking three-dimensional aster centration dynamics in eggs with manipulated shapes, we show that aster geometry resulting from MT growth and interaction with cell boundaries dictates aster instantaneous directionality, yielding cell shape-dependent centering trajectories. Aster laser surgery and modeling suggest that dynein-dependent MT cytoplasmic pulling forces that scale to MT length function to convert aster geometry into directionality. In contrast, aster speed remains largely independent of aster size, shape, or absolute dynein activity, which suggests it may be predominantly determined by aster growth rate rather than MT force amplitude. These studies begin to define the geometrical principles that control aster movements.
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Affiliation(s)
| | - Akatsuki Kimura
- Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima 411-8540, Japan National Institute of Genetics, Mishima 411-8540, Japan Institut Curie, Centre National de la Recherche Scientifique UMR 144, 75248 Paris, France
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43
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Gladilin E, Eils R, Peshkin L. On the embryonic cell division beyond the contractile ring mechanism: experimental and computational investigation of effects of vitelline confinement, temperature and egg size. PeerJ 2015; 3:e1490. [PMID: 26713241 PMCID: PMC4690382 DOI: 10.7717/peerj.1490] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 11/19/2015] [Indexed: 12/31/2022] Open
Abstract
Embryonic cell division is a mechanical process which is predominantly driven by contraction of the cleavage furrow and response of the remaining cellular matter. While most previous studies focused on contractile ring mechanisms of cytokinesis, effects of environmental factors such as pericellular vitelline membrane and temperature on the mechanics of dividing cells were rarely studied. Here, we apply a model-based analysis to the time-lapse imaging data of two species (Saccoglossus kowalevskii and Xenopus laevis) with relatively large eggs, with the goal of revealing the effects of temperature and vitelline envelope on the mechanics of the first embryonic cell division. We constructed a numerical model of cytokinesis to estimate the effects of vitelline confinement on cellular deformation and to predict deformation of cellular contours. We used the deviations of our computational predictions from experimentally observed cell elongation to adjust variable parameters of the contractile ring model and to quantify the contribution of other factors (constitutive cell properties, spindle polarization) that may influence the mechanics and shape of dividing cells. We find that temperature affects the size and rate of dilatation of the vitelline membrane surrounding fertilized eggs and show that in native (not artificially devitellinized) egg cells the effects of temperature and vitelline envelope on mechanics of cell division are tightly interlinked. In particular, our results support the view that vitelline membrane fulfills an important role of micromechanical environment around the early embryo the absence or improper function of which under moderately elevated temperature impairs normal development. Furthermore, our findings suggest the existence of scale-dependent mechanisms that contribute to cytokinesis in species with different egg size, and challenge the view of mechanics of embryonic cell division as a scale-independent phenomenon.
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Affiliation(s)
- Evgeny Gladilin
- Theoretical Bioinformatics, German Cancer Research Center , Heidelberg , Germany ; BioQuant and IPMB, University Heidelberg , Heidelberg , Germany
| | - Roland Eils
- Theoretical Bioinformatics, German Cancer Research Center , Heidelberg , Germany ; BioQuant and IPMB, University Heidelberg , Heidelberg , Germany
| | - Leonid Peshkin
- Systems Biology, Harvad Medical School , Boston, MA , USA
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44
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The use of compressive sensing and peak detection in the reconstruction of microtubules length time series in the process of dynamic instability. Comput Biol Med 2015; 65:25-33. [DOI: 10.1016/j.compbiomed.2015.07.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 07/15/2015] [Accepted: 07/16/2015] [Indexed: 12/23/2022]
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45
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46
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Mary H, Fouchard J, Gay G, Reyes C, Gauthier T, Gruget C, Pécréaux J, Tournier S, Gachet Y. Fission yeast kinesin-8 controls chromosome congression independently of oscillations. J Cell Sci 2015; 128:3720-30. [PMID: 26359299 PMCID: PMC4631777 DOI: 10.1242/jcs.160465] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 09/03/2015] [Indexed: 01/09/2023] Open
Abstract
In higher eukaryotes, efficient chromosome congression relies, among other players, on the activity of chromokinesins. Here, we provide a quantitative analysis of kinetochore oscillations and positioning in Schizosaccharomyces pombe, a model organism lacking chromokinesins. In wild-type cells, chromosomes align during prophase and, while oscillating, maintain this alignment throughout metaphase. Chromosome oscillations are dispensable both for kinetochore congression and stable kinetochore alignment during metaphase. In higher eukaryotes, kinesin-8 family members control chromosome congression by regulating their oscillations. By contrast, here, we demonstrate that fission yeast kinesin-8 controls chromosome congression by an alternative mechanism. We propose that kinesin-8 aligns chromosomes by controlling pulling forces in a length-dependent manner. A coarse-grained model of chromosome segregation implemented with a length-dependent process that controls the force at kinetochores is necessary and sufficient to mimic kinetochore alignment, and prevents the appearance of lagging chromosomes. Taken together, these data illustrate how the local action of a motor protein at kinetochores provides spatial cues within the spindle to align chromosomes and to prevent aneuploidy. Highlighted Article: Quantitative analysis in S. pombe reveals that chromosome oscillations are dispensable for kinetochore congression in mitosis. Kinesin-8 controls chromosome congression through length-dependent pulling forces.
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Affiliation(s)
- Hadrien Mary
- Université de Toulouse, LBCMCP, 118 route de Narbonne, Toulouse F-31062, France CNRS, LBCMCP-UMR5088, Toulouse F-31062, France
| | - Jonathan Fouchard
- Université de Toulouse, LBCMCP, 118 route de Narbonne, Toulouse F-31062, France CNRS, LBCMCP-UMR5088, Toulouse F-31062, France
| | - Guillaume Gay
- DAMCB, 43 rue Horace Bertin, Marseille 13005, France
| | - Céline Reyes
- Université de Toulouse, LBCMCP, 118 route de Narbonne, Toulouse F-31062, France CNRS, LBCMCP-UMR5088, Toulouse F-31062, France
| | - Tiphaine Gauthier
- Université de Toulouse, LBCMCP, 118 route de Narbonne, Toulouse F-31062, France CNRS, LBCMCP-UMR5088, Toulouse F-31062, France
| | - Clémence Gruget
- Université de Toulouse, LBCMCP, 118 route de Narbonne, Toulouse F-31062, France CNRS, LBCMCP-UMR5088, Toulouse F-31062, France
| | - Jacques Pécréaux
- IGDR, Institute of Genetics and Development of Rennes, University Rennes 1, Rennes F-35043, France
| | - Sylvie Tournier
- Université de Toulouse, LBCMCP, 118 route de Narbonne, Toulouse F-31062, France CNRS, LBCMCP-UMR5088, Toulouse F-31062, France
| | - Yannick Gachet
- Université de Toulouse, LBCMCP, 118 route de Narbonne, Toulouse F-31062, France CNRS, LBCMCP-UMR5088, Toulouse F-31062, France
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Field CM, Groen AC, Nguyen PA, Mitchison TJ. Spindle-to-cortex communication in cleaving, polyspermic Xenopus eggs. Mol Biol Cell 2015; 26:3628-40. [PMID: 26310438 PMCID: PMC4603933 DOI: 10.1091/mbc.e15-04-0233] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 08/18/2015] [Indexed: 12/01/2022] Open
Abstract
Polyspermic Xenopus eggs and a cytokinesis extract system were used to investigate spindle-to-cortex communication, which positions cleavage furrows. Chromosome passenger complex recruitment to microtubule bundles between asters plays a key role and is positively influenced by microtubule stabilization and proximity to chromatin. Mitotic spindles specify cleavage planes in early embryos by communicating their position and orientation to the cell cortex using microtubule asters that grow out from the spindle poles during anaphase. Chromatin also plays a poorly understood role. Polyspermic fertilization provides a natural experiment in which aster pairs from the same spindle (sister asters) have chromatin between them, whereas asters pairs from different spindles (nonsisters) do not. In frogs, only sister aster pairs induce furrows. We found that only sister asters recruited two conserved furrow-inducing signaling complexes, chromosome passenger complex (CPC) and Centralspindlin, to a plane between them. This explains why only sister pairs induce furrows. We then investigated factors that influenced CPC recruitment to microtubule bundles in intact eggs and a cytokinesis extract system. We found that microtubule stabilization, optimal starting distance between asters, and proximity to chromatin all favored CPC recruitment. We propose a model in which proximity to chromatin biases initial CPC recruitment to microtubule bundles between asters from the same spindle. Next a positive feedback between CPC recruitment and microtubule stabilization promotes lateral growth of a plane of CPC-positive microtubule bundles out to the cortex to position the furrow.
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Affiliation(s)
- Christine M Field
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115; Marine Biological Laboratory, Woods Hole, MA 02143
| | - Aaron C Groen
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115; Marine Biological Laboratory, Woods Hole, MA 02143
| | - Phuong A Nguyen
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115; Marine Biological Laboratory, Woods Hole, MA 02143
| | - Timothy J Mitchison
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115; Marine Biological Laboratory, Woods Hole, MA 02143
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48
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Hara Y, Merten CA. Dynein-Based Accumulation of Membranes Regulates Nuclear Expansion in Xenopus laevis Egg Extracts. Dev Cell 2015; 33:562-75. [PMID: 26004509 DOI: 10.1016/j.devcel.2015.04.016] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 03/02/2015] [Accepted: 04/22/2015] [Indexed: 10/23/2022]
Abstract
Nuclear size changes dynamically during development and has long been observed to correlate with the space surrounding the nucleus, as well as with the volume of the cell. Here we combine an in vitro cell-free system of Xenopus laevis egg extract with microfluidic devices to systematically analyze the effect of spatial constraints. The speed of nuclear expansion depended on the available space surrounding the nucleus up to a threshold volume in the nanoliter range, herein referred to as the nuclear domain. Under spatial constraints smaller than this nuclear domain, the size of microtubule-occupied space surrounding the nucleus turned out to be limiting for the accumulation of membranes around the nucleus via the motor protein dynein, therefore determining the speed of nuclear expansion. This mechanism explains how spatial information surrounding the nucleus, such as the positioning of the nucleus inside the cell, can control nuclear expansion.
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Affiliation(s)
- Yuki Hara
- Genome Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany.
| | - Christoph A Merten
- Genome Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany.
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49
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Ishihara K, Nguyen PA, Wühr M, Groen AC, Field CM, Mitchison TJ. Organization of early frog embryos by chemical waves emanating from centrosomes. Philos Trans R Soc Lond B Biol Sci 2015; 369:rstb.2013.0454. [PMID: 25047608 DOI: 10.1098/rstb.2013.0454] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The large cells in early vertebrate development face an extreme physical challenge in organizing their cytoplasm. For example, amphibian embryos have to divide cytoplasm that spans hundreds of micrometres every 30 min according to a precise geometry, a remarkable accomplishment given the extreme difference between molecular and cellular scales in this system. How do the biochemical reactions occurring at the molecular scale lead to this emergent behaviour of the cell as a whole? Based on recent findings, we propose that the centrosome plays a crucial role by initiating two autocatalytic reactions that travel across the large cytoplasm as chemical waves. Waves of mitotic entry and exit propagate out from centrosomes using the Cdk1 oscillator to coordinate the timing of cell division. Waves of microtubule-stimulated microtubule nucleation propagate out to assemble large asters that position spindles for the following mitosis and establish cleavage plane geometry. By initiating these chemical waves, the centrosome rapidly organizes the large cytoplasm during the short embryonic cell cycle, which would be impossible using more conventional mechanisms such as diffusion or nucleation by structural templating. Large embryo cells provide valuable insights to how cells control chemical waves, which may be a general principle for cytoplasmic organization.
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Affiliation(s)
- Keisuke Ishihara
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA Marine Biological Laboratory, Woods Hole, MA, USA
| | - Phuong A Nguyen
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA Marine Biological Laboratory, Woods Hole, MA, USA
| | - Martin Wühr
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA Marine Biological Laboratory, Woods Hole, MA, USA
| | - Aaron C Groen
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA Marine Biological Laboratory, Woods Hole, MA, USA
| | - Christine M Field
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA Marine Biological Laboratory, Woods Hole, MA, USA
| | - Timothy J Mitchison
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA Marine Biological Laboratory, Woods Hole, MA, USA
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50
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Ward JJ, Roque H, Antony C, Nédélec F. Mechanical design principles of a mitotic spindle. eLife 2014; 3:e03398. [PMID: 25521247 PMCID: PMC4290452 DOI: 10.7554/elife.03398] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 12/17/2014] [Indexed: 12/11/2022] Open
Abstract
An organised spindle is crucial to the fidelity of chromosome segregation, but the relationship between spindle structure and function is not well understood in any cell type. The anaphase B spindle in fission yeast has a slender morphology and must elongate against compressive forces. This 'pushing' mode of chromosome transport renders the spindle susceptible to breakage, as observed in cells with a variety of defects. Here we perform electron tomographic analyses of the spindle, which suggest that it organises a limited supply of structural components to increase its compressive strength. Structural integrity is maintained throughout the spindle's fourfold elongation by organising microtubules into a rigid transverse array, preserving correct microtubule number and dynamically rescaling microtubule length.
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Affiliation(s)
- Jonathan J Ward
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Hélio Roque
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Claude Antony
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - François Nédélec
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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