1
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Tam R, Harris TJ. Centrosome-organized plasma membrane infoldings linked to growth of a cortical actin domain. J Cell Biol 2024; 223:e202403115. [PMID: 38935075 PMCID: PMC11215285 DOI: 10.1083/jcb.202403115] [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: 03/26/2024] [Revised: 05/27/2024] [Accepted: 06/13/2024] [Indexed: 06/28/2024] Open
Abstract
Regulated cell shape change requires the induction of cortical cytoskeletal domains. Often, local changes to plasma membrane (PM) topography are involved. Centrosomes organize cortical domains and can affect PM topography by locally pulling the PM inward. Are these centrosome effects coupled? At the syncytial Drosophila embryo cortex, centrosome-induced actin caps grow into dome-like compartments for mitoses. We found the nascent cap to be a collection of PM folds and tubules formed over the astral centrosomal MT array. The localized infoldings require centrosome and dynein activities, and myosin-based surface tension prevents them elsewhere. Centrosome-engaged PM infoldings become specifically enriched with an Arp2/3 induction pathway. Arp2/3 actin network growth between the infoldings counterbalances centrosomal pulling forces and disperses the folds for actin cap expansion. Abnormal domain topography with either centrosome or Arp2/3 disruption correlates with decreased exocytic vesicle association. Together, our data implicate centrosome-organized PM infoldings in coordinating Arp2/3 network growth and exocytosis for cortical domain assembly.
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Affiliation(s)
- Rebecca Tam
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Tony J.C. Harris
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
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2
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Hsu CR, Sangha G, Fan W, Zheng J, Sugioka K. Contractile ring mechanosensation and its anillin-dependent tuning during early embryogenesis. Nat Commun 2023; 14:8138. [PMID: 38065974 PMCID: PMC10709429 DOI: 10.1038/s41467-023-43996-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023] Open
Abstract
Cytokinesis plays crucial roles in morphogenesis. Previous studies have examined how tissue mechanics influences the position and closure direction of the contractile ring. However, the mechanisms by which the ring senses tissue mechanics remain largely elusive. Here, we show the mechanism of contractile ring mechanosensation and its tuning during asymmetric ring closure of Caenorhabditis elegans embryos. Integrative analysis of ring closure and cell cortex dynamics revealed that mechanical suppression of the ring-directed cortical flow is associated with asymmetric ring closure. Consistently, artificial obstruction of ring-directed cortical flow induces asymmetric ring closure in otherwise symmetrically dividing cells. Anillin is vital for mechanosensation. Our genetic analysis suggests that the positive feedback loop among ring-directed cortical flow, myosin enrichment, and ring constriction constitutes a mechanosensitive pathway driving asymmetric ring closure. These findings and developed tools should advance the 4D mechanobiology of cytokinesis in more complex tissues.
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Affiliation(s)
- Christina Rou Hsu
- Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T1Z3, Canada
- Department of Zoology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T1Z3, Canada
| | - Gaganpreet Sangha
- Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T1Z3, Canada
- Department of Zoology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T1Z3, Canada
| | - Wayne Fan
- Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T1Z3, Canada
- Department of Zoology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T1Z3, Canada
| | - Joey Zheng
- Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T1Z3, Canada
- Department of Zoology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T1Z3, Canada
| | - Kenji Sugioka
- Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T1Z3, Canada.
- Department of Zoology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T1Z3, Canada.
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3
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Okada A, Yumura S. Cleavage furrow positioning in dividing Dictyostelium cells. Cytoskeleton (Hoboken) 2023; 80:448-460. [PMID: 37650534 DOI: 10.1002/cm.21784] [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: 05/28/2023] [Revised: 08/14/2023] [Accepted: 08/19/2023] [Indexed: 09/01/2023]
Abstract
Accurate placement of the cleavage furrow is crucial for successful cell division. Recent advancements have revealed that diverse mechanisms have evolved across different branches of the phylogenetic tree. Here, we employed Dictyostelium cells to validate previous models. We observed that during metaphase and early anaphase, mitotic spindles exhibited random rotary movements which ceased when the spindle elongated by approximately 7 μm. At this point, astral microtubules reached the polar cell cortex and fixed the spindle axis, causing cells to elongate by extending polar pseudopods and divide along the spindle axis. Therefore, the position of the furrow is determined when the spindle orientation is fixed. The distal ends of astral microtubules stimulate the extension of pseudopods at the polar cortex. One signal for pseudopod extension may be phosphatidylinositol trisphosphate in the cell membrane, but there appears to be another unknown signal. At the onset of polar pseudopod extension, cortical flow began from both poles toward the equator. We suggest that polar stimulation by astral microtubules determines the furrow position, induces polar pseudopod extension and cortical flow, and accumulates the elements necessary for the construction of the contractile ring.
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Affiliation(s)
- Akiko Okada
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, Japan
| | - Shigehiko Yumura
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, Japan
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4
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Ozugergin I, Piekny A. Diversity is the spice of life: An overview of how cytokinesis regulation varies with cell type. Front Cell Dev Biol 2022; 10:1007614. [PMID: 36420142 PMCID: PMC9676254 DOI: 10.3389/fcell.2022.1007614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 10/24/2022] [Indexed: 09/01/2023] Open
Abstract
Cytokinesis is required to physically cleave a cell into two daughters at the end of mitosis. Decades of research have led to a comprehensive understanding of the core cytokinesis machinery and how it is regulated in animal cells, however this knowledge was generated using single cells cultured in vitro, or in early embryos before tissues develop. This raises the question of how cytokinesis is regulated in diverse animal cell types and developmental contexts. Recent studies of distinct cell types in the same organism or in similar cell types from different organisms have revealed striking differences in how cytokinesis is regulated, which includes different threshold requirements for the structural components and the mechanisms that regulate them. In this review, we highlight these differences with an emphasis on pathways that are independent of the mitotic spindle, and operate through signals associated with the cortex, kinetochores, or chromatin.
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Affiliation(s)
- Imge Ozugergin
- Department of Biology, McGill University, Montreal, QC, Canada
- Department of Biology, Concordia University, Montreal, QC, Canada
| | - Alisa Piekny
- Department of Biology, Concordia University, Montreal, QC, Canada
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5
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Hirsch SM, Edwards F, Shirasu-Hiza M, Dumont J, Canman JC. Functional midbody assembly in the absence of a central spindle. J Cell Biol 2022; 221:e202011085. [PMID: 34994802 PMCID: PMC8751756 DOI: 10.1083/jcb.202011085] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 10/13/2021] [Accepted: 12/10/2021] [Indexed: 12/28/2022] Open
Abstract
Contractile ring constriction during cytokinesis is thought to compact central spindle microtubules to form the midbody, an antiparallel microtubule bundle at the intercellular bridge. In Caenorhabditis elegans, central spindle microtubule assembly requires targeting of the CLASP family protein CLS-2 to the kinetochores in metaphase and spindle midzone in anaphase. CLS-2 targeting is mediated by the CENP-F-like HCP-1/2, but their roles in cytokinesis and midbody assembly are not known. We found that although HCP-1 and HCP-2 mostly function cooperatively, HCP-1 plays a more primary role in promoting CLS-2-dependent central spindle microtubule assembly. HCP-1/2 codisrupted embryos did not form central spindles but completed cytokinesis and formed functional midbodies capable of supporting abscission. These central spindle-independent midbodies appeared to form via contractile ring constriction-driven bundling of astral microtubules at the furrow tip. This work suggests that, in the absence of a central spindle, astral microtubules can support midbody assembly and that midbody assembly is more predictive of successful cytokinesis than central spindle assembly.
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Affiliation(s)
- Sophia M. Hirsch
- Department of Genetics and Development, Columbia University Medical Center, New York, NY
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY
| | - Frances Edwards
- Institut Jacques Monod, Centre national de la recherche scientifique, Université de Paris, Paris, France
| | - Mimi Shirasu-Hiza
- Department of Genetics and Development, Columbia University Medical Center, New York, NY
| | - Julien Dumont
- Institut Jacques Monod, Centre national de la recherche scientifique, Université de Paris, Paris, France
| | - Julie C. Canman
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY
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6
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Longhini KM, Glotzer M. Aurora A and cortical flows promote polarization and cytokinesis by inducing asymmetric ECT-2 accumulation. eLife 2022; 11:83992. [PMID: 36533896 PMCID: PMC9799973 DOI: 10.7554/elife.83992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022] Open
Abstract
In the early Caenorhabditis elegans embryo, cell polarization and cytokinesis are interrelated yet distinct processes. Here, we sought to understand a poorly understood aspect of cleavage furrow positioning. Early C. elegans embryos deficient in the cytokinetic regulator centralspindlin form furrows, due to an inhibitory activity that depends on aster positioning relative to the polar cortices. Here, we show polar relaxation is associated with depletion of cortical ECT-2, a RhoGEF, specifically at the posterior cortex. Asymmetric ECT-2 accumulation requires intact centrosomes, Aurora A (AIR-1), and myosin-dependent cortical flows. Within a localization competent ECT-2 fragment, we identified three putative phospho-acceptor sites in the PH domain of ECT-2 that render ECT-2 responsive to inhibition by AIR-1. During both polarization and cytokinesis, our results suggest that centrosomal AIR-1 breaks symmetry via ECT-2 phosphorylation; this local inhibition of ECT-2 is amplified by myosin-driven flows that generate regional ECT-2 asymmetry. Together, these mechanisms cooperate to induce polarized assembly of cortical myosin, contributing to both embryo polarization and cytokinesis.
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Affiliation(s)
- Katrina M Longhini
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States
| | - Michael Glotzer
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States
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7
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Sugioka K. Symmetry-breaking of animal cytokinesis. Semin Cell Dev Biol 2021; 127:100-109. [PMID: 34955355 DOI: 10.1016/j.semcdb.2021.12.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 12/05/2021] [Accepted: 12/16/2021] [Indexed: 12/24/2022]
Abstract
Cytokinesis is a mechanism that separates dividing cells via constriction of a supramolecular structure, the contractile ring. In animal cells, three modes of symmetry-breaking of cytokinesis result in unilateral cytokinesis, asymmetric cell division, and oriented cell division. Each mode of cytokinesis plays a significant role in tissue patterning and morphogenesis by the mechanisms that control the orientation and position of the contractile ring relative to the body axis. Despite its significance, the mechanisms involved in the symmetry-breaking of cytokinesis remain unclear in many cell types. Classical embryologists have identified that the geometric relationship between the mitotic spindle and cell cortex induces cytokinesis asymmetry; however, emerging evidence suggests that a concerted flow of compressional cell-cortex materials (cortical flow) is a spindle-independent driving force in spatial cytokinesis control. This review provides an overview of both classical and emerging mechanisms of cytokinesis asymmetry and their roles in animal development.
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Affiliation(s)
- Kenji Sugioka
- Life Sciences Institute, The University of British Columbia, Vancouver, BC V6T1Z3, Canada; Department of Zoology, The University of British Columbia, Vancouver, BC V6T1Z3, Canada.
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8
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Yamamoto K, Miura H, Ishida M, Mii Y, Kinoshita N, Takada S, Ueno N, Sawai S, Kondo Y, Aoki K. Optogenetic relaxation of actomyosin contractility uncovers mechanistic roles of cortical tension during cytokinesis. Nat Commun 2021; 12:7145. [PMID: 34880255 PMCID: PMC8654997 DOI: 10.1038/s41467-021-27458-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 11/17/2021] [Indexed: 12/14/2022] Open
Abstract
Actomyosin contractility generated cooperatively by nonmuscle myosin II and actin filaments plays essential roles in a wide range of biological processes, such as cell motility, cytokinesis, and tissue morphogenesis. However, subcellular dynamics of actomyosin contractility underlying such processes remains elusive. Here, we demonstrate an optogenetic method to induce relaxation of actomyosin contractility at the subcellular level. The system, named OptoMYPT, combines a protein phosphatase 1c (PP1c)-binding domain of MYPT1 with an optogenetic dimerizer, so that it allows light-dependent recruitment of endogenous PP1c to the plasma membrane. Blue-light illumination is sufficient to induce dephosphorylation of myosin regulatory light chains and a decrease in actomyosin contractile force in mammalian cells and Xenopus embryos. The OptoMYPT system is further employed to understand the mechanics of actomyosin-based cortical tension and contractile ring tension during cytokinesis. We find that the relaxation of cortical tension at both poles by OptoMYPT accelerated the furrow ingression rate, revealing that the cortical tension substantially antagonizes constriction of the cleavage furrow. Based on these results, the OptoMYPT system provides opportunities to understand cellular and tissue mechanics.
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Affiliation(s)
- Kei Yamamoto
- National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
| | - Haruko Miura
- National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
| | - Motohiko Ishida
- Graduate School of Arts and Sciences, University of Tokyo, Komaba, 153-8902, Tokyo, Japan
- Research Center for Complex Systems Biology, Universal Biology Institute, University of Tokyo, Komaba, 153-8902, Tokyo, Japan
| | - Yusuke Mii
- National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
- Japan Science and Technology Agency (JST), PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Noriyuki Kinoshita
- National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
| | - Shinji Takada
- National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
| | - Naoto Ueno
- National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan
- IRCC International Research Collaboration Center, National Institutes of Natural Sciences, 4-3-13 Toranomon, Minato-ku, Tokyo, 105-0001, Japan
| | - Satoshi Sawai
- Graduate School of Arts and Sciences, University of Tokyo, Komaba, 153-8902, Tokyo, Japan
- Research Center for Complex Systems Biology, Universal Biology Institute, University of Tokyo, Komaba, 153-8902, Tokyo, Japan
| | - Yohei Kondo
- National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan.
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan.
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan.
| | - Kazuhiro Aoki
- National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan.
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan.
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan.
- IRCC International Research Collaboration Center, National Institutes of Natural Sciences, 4-3-13 Toranomon, Minato-ku, Tokyo, 105-0001, Japan.
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9
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Abstract
Actin filaments and microtubules are cytoskeletal polymers that participate in many vital cell functions including division, morphogenesis, phagocytosis, and motility. Despite the persistent dogma that actin filament and microtubule networks are distinct in localization, structure, and function, a growing body of evidence shows that these elements are choreographed through intricate mechanisms sensitive to either polymer. Many proteins and cellular signals that mediate actin–microtubule interactions have already been identified. However, the impact of these regulators is typically assessed with actin filament or microtubule polymers alone, independent of the other system. Further, unconventional modes and regulators coordinating actin–microtubule interactions are still being discovered. Here we examine several methods of actin–microtubule crosstalk with an emphasis on the molecular links between both polymer systems and their higher-order interactions.
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Affiliation(s)
- Morgan L Pimm
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210
| | - Jessica L Henty-Ridilla
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210.,Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY 13210
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10
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Brunet T, Albert M, Roman W, Coyle MC, Spitzer DC, King N. A flagellate-to-amoeboid switch in the closest living relatives of animals. eLife 2021; 10:e61037. [PMID: 33448265 PMCID: PMC7895527 DOI: 10.7554/elife.61037] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 01/14/2021] [Indexed: 12/19/2022] Open
Abstract
Amoeboid cell types are fundamental to animal biology and broadly distributed across animal diversity, but their evolutionary origin is unclear. The closest living relatives of animals, the choanoflagellates, display a polarized cell architecture (with an apical flagellum encircled by microvilli) that resembles that of epithelial cells and suggests homology, but this architecture differs strikingly from the deformable phenotype of animal amoeboid cells, which instead evoke more distantly related eukaryotes, such as diverse amoebae. Here, we show that choanoflagellates subjected to confinement become amoeboid by retracting their flagella and activating myosin-based motility. This switch allows escape from confinement and is conserved across choanoflagellate diversity. The conservation of the amoeboid cell phenotype across animals and choanoflagellates, together with the conserved role of myosin, is consistent with homology of amoeboid motility in both lineages. We hypothesize that the differentiation between animal epithelial and crawling cells might have evolved from a stress-induced switch between flagellate and amoeboid forms in their single-celled ancestors.
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Affiliation(s)
- Thibaut Brunet
- Howard Hughes Medical InstituteChevy ChaseUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Marvin Albert
- Department of Molecular Life Sciences, University of ZürichZurichSwitzerland
| | - William Roman
- Department of Experimental and Health Sciences, Pompeu Fabra University (UPF), CIBERNEDBarcelonaSpain
| | - Maxwell C Coyle
- Howard Hughes Medical InstituteChevy ChaseUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Danielle C Spitzer
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Nicole King
- Howard Hughes Medical InstituteChevy ChaseUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
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11
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Pal D, Ellis A, Sepúlveda-Ramírez SP, Salgado T, Terrazas I, Reyes G, De La Rosa R, Henson JH, Shuster CB. Rac and Arp2/3-Nucleated Actin Networks Antagonize Rho During Mitotic and Meiotic Cleavages. Front Cell Dev Biol 2020; 8:591141. [PMID: 33282870 PMCID: PMC7705106 DOI: 10.3389/fcell.2020.591141] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/20/2020] [Indexed: 12/01/2022] Open
Abstract
In motile cells, the activities of the different Rho family GTPases are spatially segregated within the cell, and during cytokinesis there is evidence that this may also be the case. But while Rho’s role as the central organizer for contractile ring assembly is well established, the role of Rac and the branched actin networks it promotes is less well understood. To characterize the contributions of these proteins during cytokinesis, we manipulated Rac and Arp2/3 activity during mitosis and meiosis in sea urchin embryos and sea star oocytes. While neither Rac nor Arp2/3 were essential for early embryonic divisions, loss of either Rac or Arp2/3 activity resulted in polar body defects. Expression of activated Rac resulted in cytokinesis failure as early as the first division, and in oocytes, activated Rac suppressed both the Rho wave that traverses the oocyte prior to polar body extrusion as well as polar body formation itself. However, the inhibitory effect of Rac on cytokinesis, polar body formation and the Rho wave could be suppressed by effector-binding mutations or direct inhibition of Arp2/3. Together, these results suggest that Rac- and Arp2/3 mediated actin networks may directly antagonize Rho signaling, thus providing a potential mechanism to explain why Arp2/3-nucleated branched actin networks must be suppressed at the cell equator for successful cytokinesis.
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Affiliation(s)
- Debadrita Pal
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Andrea Ellis
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | | | - Torey Salgado
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Isabella Terrazas
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Gabriela Reyes
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Richard De La Rosa
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - John H Henson
- Department of Biology, Dickinson College, Carlisle, PA, United States
| | - Charles B Shuster
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
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12
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Gubieda AG, Packer JR, Squires I, Martin J, Rodriguez J. Going with the flow: insights from Caenorhabditis elegans zygote polarization. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190555. [PMID: 32829680 PMCID: PMC7482210 DOI: 10.1098/rstb.2019.0555] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/09/2020] [Indexed: 12/12/2022] Open
Abstract
Cell polarity is the asymmetric distribution of cellular components along a defined axis. Polarity relies on complex signalling networks between conserved patterning proteins, including the PAR (partitioning defective) proteins, which become segregated in response to upstream symmetry breaking cues. Although the mechanisms that drive the asymmetric localization of these proteins are dependent upon cell type and context, in many cases the regulation of actomyosin cytoskeleton dynamics is central to the transport, recruitment and/or stabilization of these polarity effectors into defined subcellular domains. The transport or advection of PAR proteins by an actomyosin flow was first observed in the Caenorhabditis elegans zygote more than a decade ago. Since then a multifaceted approach, using molecular methods, high-throughput screens, and biophysical and computational models, has revealed further aspects of this flow and how polarity regulators respond to and modulate it. Here, we review recent findings on the interplay between actomyosin flow and the PAR patterning networks in the polarization of the C. elegans zygote. We also discuss how these discoveries and developed methods are shaping our understanding of other flow-dependent polarizing systems. This article is part of a discussion meeting issue 'Contemporary morphogenesis'.
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Affiliation(s)
| | | | | | | | - Josana Rodriguez
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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13
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Leite J, Chan FY, Osório DS, Saramago J, Sobral AF, Silva AM, Gassmann R, Carvalho AX. Equatorial Non-muscle Myosin II and Plastin Cooperate to Align and Compact F-actin Bundles in the Cytokinetic Ring. Front Cell Dev Biol 2020; 8:573393. [PMID: 33102479 PMCID: PMC7546906 DOI: 10.3389/fcell.2020.573393] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 09/03/2020] [Indexed: 12/17/2022] Open
Abstract
Cytokinesis is the last step of cell division that physically partitions the mother cell into two daughter cells. Cytokinesis requires the assembly and constriction of a contractile ring, a circumferential array of filamentous actin (F-actin), non-muscle myosin II motors (myosin), and actin-binding proteins that forms at the cell equator. Cytokinesis is accompanied by long-range cortical flows from regions of relaxation toward regions of compression. In the C. elegans one-cell embryo, it has been suggested that anterior-directed cortical flows are the main driver of contractile ring assembly. Here, we use embryos co-expressing motor-dead and wild-type myosin to show that cortical flows can be severely reduced without major effects on contractile ring assembly and timely completion of cytokinesis. Fluorescence recovery after photobleaching in the ingressing furrow reveals that myosin recruitment kinetics are also unaffected by the absence of cortical flows. We find that myosin cooperates with the F-actin crosslinker plastin to align and compact F-actin bundles at the cell equator, and that this cross-talk is essential for cytokinesis. Our results thus argue against the idea that cortical flows are a major determinant of contractile ring assembly. Instead, we propose that contractile ring assembly requires localized concerted action of motor-competent myosin and plastin at the cell equator.
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Affiliation(s)
- Joana Leite
- Cytoskeletal Dynamics Lab, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Cytoskeletal Dynamics Lab, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Fung-Yi Chan
- Cytoskeletal Dynamics Lab, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Cytoskeletal Dynamics Lab, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Daniel S Osório
- Cytoskeletal Dynamics Lab, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Cytoskeletal Dynamics Lab, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Joana Saramago
- Cytoskeletal Dynamics Lab, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Cytoskeletal Dynamics Lab, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Ana F Sobral
- Cytoskeletal Dynamics Lab, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Cytoskeletal Dynamics Lab, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Ana M Silva
- Cytoskeletal Dynamics Lab, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Cytoskeletal Dynamics Lab, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Reto Gassmann
- Cytoskeletal Dynamics Lab, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Cytoskeletal Dynamics Lab, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Ana X Carvalho
- Cytoskeletal Dynamics Lab, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Cytoskeletal Dynamics Lab, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
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