51
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Martiel JL, Michelot A, Boujemaa-Paterski R, Blanchoin L, Berro J. Force Production by a Bundle of Growing Actin Filaments Is Limited by Its Mechanical Properties. Biophys J 2019; 118:182-192. [PMID: 31791547 DOI: 10.1016/j.bpj.2019.10.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 10/16/2019] [Accepted: 10/30/2019] [Indexed: 12/16/2022] Open
Abstract
Bundles of actin filaments are central to a large variety of cellular structures such as filopodia, stress fibers, cytokinetic rings, and focal adhesions. The mechanical properties of these bundles are critical for proper force transmission and force bearing. Previous mathematical modeling efforts have focused on bundles' rigidity and shape. However, it remains unknown how bundle length and buckling are controlled by external physical factors. In this work, we present a biophysical model for dynamic bundles of actin filaments submitted to an external load. In combination with in vitro motility assays of beads coated with formins, our model allowed us to characterize conditions for bead movement and bundle buckling. From the deformation profiles, we determined key biophysical properties of tethered actin bundles such as their rigidity and filament density.
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Affiliation(s)
- Jean-Louis Martiel
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France; CNRS, CHU Grenoble-Alpes, Inserm, TIMC-IMAG, University Grenoble-Alpes, Grenoble, France.
| | - Alphée Michelot
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France; CNRS, IBDM, Turing Centre for Living Systems, Aix Marseille University, Marseille, France
| | - Rajaa Boujemaa-Paterski
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France; Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Laurent Blanchoin
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France
| | - Julien Berro
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut; Nanobiology Institute, Yale University, West Haven, Connecticut; Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut.
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52
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Schutt KL, Moseley JB. The phosphatase inhibitor Sds23 regulates cell division symmetry in fission yeast. Mol Biol Cell 2019; 30:2880-2889. [PMID: 31553675 PMCID: PMC6822584 DOI: 10.1091/mbc.e19-05-0254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Animal and fungal cells divide through the assembly, anchoring, and constriction of a contractile actomyosin ring (CAR) during cytokinesis. The timing and position of the CAR must be tightly controlled to prevent defects in cell division, but many of the underlying signaling events remain unknown. The conserved heterotrimeric protein phosphatase PP2A controls the timing of events in mitosis, and upstream pathways including Greatwall-Ensa regulate PP2A activity. A role for PP2A in CAR regulation has been less clear, although loss of PP2A in yeast causes defects in cytokinesis. Here, we report that Sds23, an inhibitor of PP2A family protein phosphatases, promotes the symmetric division of fission yeast cells through spatial control of cytokinesis. We found that sds23∆ cells divide asymmetrically due to misplaced CAR assembly, followed by sliding of the CAR away from its assembly site. These mutant cells exhibit delayed recruitment of putative CAR anchoring proteins including the glucan synthase Bgs1. Our observations likely reflect a broader role for regulation of PP2A in cell polarity and cytokinesis because sds23∆ phenotypes were exacerbated when combined with mutations in the fission yeast Ensa homologue, Igo1. These results identify the PP2A regulatory network as a critical component in the signaling pathways coordinating cytokinesis.
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Affiliation(s)
- Katherine L Schutt
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - James B Moseley
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH 03755
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53
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Adeli Koudehi M, Rutkowski DM, Vavylonis D. Organization of associating or crosslinked actin filaments in confinement. Cytoskeleton (Hoboken) 2019; 76:532-548. [PMID: 31525281 DOI: 10.1002/cm.21565] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 09/09/2019] [Accepted: 09/12/2019] [Indexed: 12/13/2022]
Abstract
A key factor of actin cytoskeleton organization in cells is the interplay between the dynamical properties of actin filaments and cell geometry, which restricts, confines and directs their orientation. Crosslinking interactions among actin filaments, together with geometrical cues and regulatory proteins can give rise to contractile rings in dividing cells and actin rings in neurons. Motivated by recent in vitro experiments, in this work we performed computer simulations to study basic aspects of the interplay between confinement and attractive interactions between actin filaments. We used a spring-bead model and Brownian dynamics to simulate semiflexible actin filaments that polymerize in a confining sphere with a rate proportional to the monomer concentration. We model crosslinking, or attraction through the depletion interaction, implicitly as an attractive short-range potential between filament beads. In confining geometries smaller than the persistence length of actin filaments, we show rings can form by curving of filaments of length comparable to, or longer than the confinement diameter. Rings form for optimal ranges of attractive interactions that exist in between open bundles, irregular loops, aggregated, and unbundled morphologies. The probability of ring formation is promoted by attraction to the confining sphere boundary and decreases for large radii and initial monomer concentrations, in agreement with prior experimental data. The model reproduces ring formation along the flat plane of oblate ellipsoids.
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54
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Hercyk B, Das M. Rho Family GTPases in Fission Yeast Cytokinesis. Commun Integr Biol 2019; 12:171-180. [PMID: 31666919 PMCID: PMC6802929 DOI: 10.1080/19420889.2019.1678453] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 09/20/2019] [Accepted: 09/23/2019] [Indexed: 12/22/2022] Open
Abstract
During cytokinesis, actomyosin ring constriction drives furrow formation. In animal cells, Rho GTPases drive this process through the positioning and assembly of the actomyosin ring, and through extracellular matrix remodeling within the furrow. In the fission yeast S. pombe, actomyosin ring constriction and septum formation are concurrent processes. While S. pombe is the primary source from which the mechanics of ring assembly and constriction stem, much less is known about the regulation of Rho GTPases that control these processes. Of the six Rho GTPases encoded in S. pombe, only Rho1, the RhoA homologue, has been shown to be essential for cytokinesis. While Rho3, Rho4, and Cdc42 have defined roles in cytokinesis, Rho2 and Rho5 play minor to no roles in this process. Here we review the roles of the Rho GTPases during cytokinesis, with a focus on their regulation, and discuss whether crosstalk between GTPases, as has been reported in other organisms, exists during cytokinesis in S. pombe.
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Affiliation(s)
- Brian Hercyk
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
| | - Maitreyi Das
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
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55
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Ramos M, Cortés JCG, Sato M, Rincón SA, Moreno MB, Clemente-Ramos JÁ, Osumi M, Pérez P, Ribas JC. Two S. pombe septation phases differ in ingression rate, septum structure, and response to F-actin loss. J Cell Biol 2019; 218:4171-4194. [PMID: 31597680 PMCID: PMC6891078 DOI: 10.1083/jcb.201808163] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 04/19/2019] [Accepted: 09/10/2019] [Indexed: 12/28/2022] Open
Abstract
Ramos et al. establish that fission yeast septation proceeds in two phases. Initially, the septum is immature and, upon F-actin depolymerization, loses the Bgs1 glucan synthase and fails to ingress. During a second phase, the mature septum can maintain Bgs1 and ingression without F-actin, and ingression becomes Cdc42 and exocyst dependent. In fission yeast, cytokinesis requires a contractile actomyosin ring (CR) coupled to membrane and septum ingression. Septation proceeds in two phases. In anaphase B, the septum ingresses slowly. During telophase, the ingression rate increases, and the CR becomes dispensable. Here, we explore the relationship between the CR and septation by analyzing septum ultrastructure, ingression, and septation proteins in cells lacking F-actin. We show that the two phases of septation correlate with septum maturation and the response of cells to F-actin removal. During the first phase, the septum is immature and, following F-actin removal, rapidly loses the Bgs1 glucan synthase from the membrane edge and fails to ingress. During the second phase, the rapidly ingressing mature septum can maintain a Bgs1 ring and septum ingression without F-actin, but ingression becomes Cdc42 and exocyst dependent. Our results provide new insights into fungal cytokinesis and reveal the dual function of CR as an essential landmark for the concentration of Bgs1 and a contractile structure that maintains septum shape and synthesis.
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Affiliation(s)
- Mariona Ramos
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
| | - Juan Carlos G Cortés
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
| | - Mamiko Sato
- Laboratory of Electron Microscopy/Bio-imaging Center, Japan Women's University, Bunkyo-ku, Tokyo, Japan
| | - Sergio A Rincón
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
| | - M Belén Moreno
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
| | - José Ángel Clemente-Ramos
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
| | - Masako Osumi
- Laboratory of Electron Microscopy/Bio-imaging Center, Japan Women's University, Bunkyo-ku, Tokyo, Japan.,Integrated Imaging Research Support, Chiyoda-ku, Tokyo, Japan
| | - Pilar Pérez
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
| | - Juan Carlos Ribas
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
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56
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Palani S, Köster DV, Hatano T, Kamnev A, Kanamaru T, Brooker HR, Hernandez-Fernaud JR, Jones AME, Millar JBA, Mulvihill DP, Balasubramanian MK. Phosphoregulation of tropomyosin is crucial for actin cable turnover and division site placement. J Cell Biol 2019; 218:3548-3559. [PMID: 31597679 PMCID: PMC6829654 DOI: 10.1083/jcb.201809089] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 11/29/2018] [Accepted: 08/30/2019] [Indexed: 02/05/2023] Open
Abstract
Palani et al. reveal a new mechanism by which the F-actin binding protein tropomyosin is regulated. They find that phosphorylation of tropomyosin reduces its affinity for F-actin, allowing the competing Adf1 to bind and sever actin filaments. Tropomyosin is a coiled-coil actin binding protein key to the stability of actin filaments. In muscle cells, tropomyosin is subject to calcium regulation, but its regulation in nonmuscle cells is not understood. Here, we provide evidence that the fission yeast tropomyosin, Cdc8, is regulated by phosphorylation of a serine residue. Failure of phosphorylation leads to an increased number and stability of actin cables and causes misplacement of the division site in certain genetic backgrounds. Phosphorylation of Cdc8 weakens its interaction with actin filaments. Furthermore, we show through in vitro reconstitution that phosphorylation-mediated release of Cdc8 from actin filaments facilitates access of the actin-severing protein Adf1 and subsequent filament disassembly. These studies establish that phosphorylation may be a key mode of regulation of nonmuscle tropomyosins, which in fission yeast controls actin filament stability and division site placement.
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Affiliation(s)
- Saravanan Palani
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Darius V Köster
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Tomoyuki Hatano
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Anton Kamnev
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Taishi Kanamaru
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Holly R Brooker
- School of Biosciences, University of Kent, Canterbury, Kent, UK
| | | | | | - Jonathan B A Millar
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | | | - Mohan K Balasubramanian
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
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57
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Pollard TD. Cell Motility and Cytokinesis: From Mysteries to Molecular Mechanisms in Five Decades. Annu Rev Cell Dev Biol 2019; 35:1-28. [PMID: 31394047 DOI: 10.1146/annurev-cellbio-100818-125427] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This is the story of someone who has been fortunate to work in a field of research where essentially nothing was known at the outset but that blossomed with the discovery of profound insights about two basic biological processes: cell motility and cytokinesis. The field started with no molecules, just a few people, and primitive methods. Over time, technological advances in biophysics, biochemistry, and microscopy allowed the combined efforts of scientists in hundreds of laboratories to explain mysterious processes with molecular mechanisms that can be embodied in mathematical equations and simulated by computers. The success of this field is a tribute to the power of the reductionist strategy for understanding biology.
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Affiliation(s)
- Thomas D Pollard
- Departments of Molecular, Cellular and Developmental Biology; Molecular Biophysics and Biochemistry; and Cell Biology, Yale University, New Haven, Connecticut 06520-8103, USA;
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58
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Tarnopol RL, Bowden S, Hinkle K, Balakrishnan K, Nishii A, Kaczmarek CJ, Pawloski T, Vecchiarelli AG. Lessons from a Minimal Genome: What Are the Essential Organizing Principles of a Cell Built from Scratch? Chembiochem 2019; 20:2535-2545. [DOI: 10.1002/cbic.201900249] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Rebecca L. Tarnopol
- Department of Molecular, Cellular, and Developmental Biology University of Michigan Ann Arbor MI 48109 USA
| | - Sierra Bowden
- Department of Molecular, Cellular, and Developmental Biology University of Michigan Ann Arbor MI 48109 USA
| | - Kevin Hinkle
- Department of Molecular, Cellular, and Developmental Biology University of Michigan Ann Arbor MI 48109 USA
| | - Krithika Balakrishnan
- Department of Molecular, Cellular, and Developmental Biology University of Michigan Ann Arbor MI 48109 USA
| | - Akira Nishii
- Department of Molecular, Cellular, and Developmental Biology University of Michigan Ann Arbor MI 48109 USA
| | - Caleb J. Kaczmarek
- Department of Molecular, Cellular, and Developmental Biology University of Michigan Ann Arbor MI 48109 USA
| | - Tara Pawloski
- Department of Molecular, Cellular, and Developmental Biology University of Michigan Ann Arbor MI 48109 USA
| | - Anthony G. Vecchiarelli
- Department of Molecular, Cellular, and Developmental Biology University of Michigan Ann Arbor MI 48109 USA
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59
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Ma R, Berro J. Crosslinking actin networks produces compressive force. Cytoskeleton (Hoboken) 2019; 76:346-354. [PMID: 31278856 DOI: 10.1002/cm.21552] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 06/21/2019] [Accepted: 07/02/2019] [Indexed: 11/11/2022]
Abstract
Actin has been shown to be essential for clathrin-mediated endocytosis in yeast. However, actin polymerization alone is likely insufficient to produce enough force to deform the membrane against the huge turgor pressure of yeast cells. In this paper, we used Brownian dynamics simulations to demonstrate that crosslinking of a meshwork of nonpolymerizing actin filaments is able to produce compressive forces. We show that the force can be up to several thousand pico-Newtons if the crosslinker has a high stiffness. The force decays over time as a result of crosslinker turnover, and is a result of converting chemical binding energy into elastic energy.
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Affiliation(s)
- Rui Ma
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut.,Nanobiology Institute, Yale University, West Haven, Connecticut
| | - Julien Berro
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut.,Nanobiology Institute, Yale University, West Haven, Connecticut.,Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut
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60
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Kashiwazaki J, Yoneda Y, Mutoh T, Arai R, Yoshida M, Mabuchi I. A unique kinesin-like protein, Klp8, is involved in mitosis and cell morphology through microtubule stabilization. Cytoskeleton (Hoboken) 2019; 76:355-367. [PMID: 31276301 DOI: 10.1002/cm.21551] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 05/23/2019] [Accepted: 07/01/2019] [Indexed: 11/10/2022]
Abstract
Kinesins are microtubule (MT)-based motors involved in various cellular functions including intracellular transport of vesicles and organelles, and dynamics of chromosomes during cell division. The fission yeast Schizosaccharomyces pombe expresses nine kinesin-like proteins (klps). Klp8 is one of them and has not been characterized yet though it has been reported to localize at the division site. Here, we studied function and localization of Klp8 in S. pombe cells. The gene klp8+ was not essential for both viability and cytoskeletal organization. Klp8-YFP was concentrated as medial cortical dots during interphase, and organized into a ring at the division site during mitosis. The Klp8 ring seemed to be localized in the space between the actomyosin contractile ring and the plasma membrane. The Klp8 ring shrank as cytokinesis proceeded. In klp8-deleted (Δ) cells, the speed of spindle elongation during anaphase B was slowed down. Overproduction of Klp8 caused bent or elongated cells, in which MTs were abnormally elongated and less dynamic than those in normal cells. Deletion of klp8+ gene suppressed the delay in mitotic entry in blt1Δ cells. These results suggest that Klp8 is involved in mitosis and cell morphology through MT stabilization.
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Affiliation(s)
- Jun Kashiwazaki
- Department of Life Science, Gakushuin University, Tokyo, Japan
| | - Yumi Yoneda
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Tadashi Mutoh
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Ritsuko Arai
- Chemical Genetics Laboratory, RIKEN, Wako, Japan
| | - Minoru Yoshida
- Chemical Genetics Laboratory, RIKEN, Wako, Japan.,CREST Research Project, Japan Science and Technology Corporation, Wako, Japan
| | - Issei Mabuchi
- Department of Life Science, Gakushuin University, Tokyo, Japan.,Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
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61
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Arbizzani F, Rincon SA, Paoletti A. Increasing ergosterol levels delays formin-dependent assembly of F-actin cables and disrupts division plane positioning in fission yeast. J Cell Sci 2019; 132:jcs.227447. [PMID: 31217286 DOI: 10.1242/jcs.227447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 05/31/2019] [Indexed: 11/20/2022] Open
Abstract
In most eukaryotes, cytokinesis is mediated by the constriction of a contractile acto-myosin ring (CR), which promotes the ingression of the cleavage furrow. Many components of the CR interact with plasma membrane lipids suggesting that lipids may regulate CR assembly and function. Although there is clear evidence that phosphoinositides play an important role in cytokinesis, much less is known about the role of sterols in this process. Here, we studied how sterols influence division plane positioning and CR assembly in fission yeast. We show that increasing ergosterol levels in the plasma membrane blocks the assembly of F-actin cables from cytokinetic precursor nodes, preventing their compaction into a ring. Abnormal F-actin cables form after a delay, leading to randomly placed septa. Since the formin Cdc12 was detected on cytokinetic precursors and the phenotype can be partially rescued by inhibiting the Arp2/3 complex, which competes with formins for F-actin nucleation, we propose that ergosterol may inhibit formin dependent assembly of F-actin cables from cytokinetic precursors.
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Affiliation(s)
| | - Sergio A Rincon
- Institut Curie, PSL University, CNRS UMR 144, 75005 Paris, France .,Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, Salamanca 37007, Spain
| | - Anne Paoletti
- Institut Curie, PSL University, CNRS UMR 144, 75005 Paris, France
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62
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Krueger D, Quinkler T, Mortensen SA, Sachse C, De Renzis S. Cross-linker-mediated regulation of actin network organization controls tissue morphogenesis. J Cell Biol 2019; 218:2743-2761. [PMID: 31253650 PMCID: PMC6683744 DOI: 10.1083/jcb.201811127] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 04/29/2019] [Accepted: 06/04/2019] [Indexed: 11/22/2022] Open
Abstract
Spatio-temporal organization of actomyosin contraction during epithelial morphogenesis in Drosophila is regulated by the developmental modulation of actin cross-linking through induction of Bottleneck. Bottleneck protein restrains contractility by promoting actin bundling, functioning in a similar way to Filamin and in an opposite way to Fimbrin. Contraction of cortical actomyosin networks driven by myosin activation controls cell shape changes and tissue morphogenesis during animal development. In vitro studies suggest that contractility also depends on the geometrical organization of actin filaments. Here we analyze the function of actomyosin network topology in vivo using optogenetic stimulation of myosin-II in Drosophila embryos. We show that early during cellularization, hexagonally arrayed actomyosin fibers are resilient to myosin-II activation. Actomyosin fibers then acquire a ring-like conformation and become contractile and sensitive to myosin-II. This transition is controlled by Bottleneck, a Drosophila unique protein expressed for only a short time during early cellularization, which we show regulates actin bundling. In addition, it requires two opposing actin cross-linkers, Filamin and Fimbrin. Filamin acts synergistically with Bottleneck to facilitate hexagonal patterning, while Fimbrin controls remodeling of the hexagonal network into contractile rings. Thus, actin cross-linking regulates the spatio-temporal organization of actomyosin contraction in vivo, which is critical for tissue morphogenesis.
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Affiliation(s)
- Daniel Krueger
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Collaboration for joint PhD degree between European Molecular Biology Laboratory and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Theresa Quinkler
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Simon Arnold Mortensen
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Carsten Sachse
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Ernst-Ruska Center for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, Jülich, Germany
| | - Stefano De Renzis
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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63
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Chatterjee M, Pollard TD. The Functionally Important N-Terminal Half of Fission Yeast Mid1p Anillin Is Intrinsically Disordered and Undergoes Phase Separation. Biochemistry 2019; 58:3031-3041. [PMID: 31243991 DOI: 10.1021/acs.biochem.9b00217] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Division of fungal and animal cells depends on scaffold proteins called anillins. Cytokinesis by the fission yeast Schizosaccharomyces pombe is compromised by the loss of anillin Mid1p (Mid1, UniProtKB P78953 ), because cytokinesis organizing centers, called nodes, are misplaced and fail to acquire myosin-II, so they assemble slowly into abnormal contractile rings. The C-terminal half of Mid1p consists of lipid binding C2 and PH domains, but the N-terminal half (Mid1p-N452) performs most of the functions of the full-length protein. Little is known about the structure of the N-terminal half of Mid1p, so we investigated its physical properties using structure prediction tools, spectroscopic techniques, and hydrodynamic measurements. The data indicate that Mid1p-N452 is intrinsically disordered but moderately compact. Recombinant Mid1p-N452 purified from insect cells was phosphorylated, which weakens its tendency to aggregate. Purified Mid1p-N452 demixes into liquid droplets at concentrations far below its concentration in nodes. These physical properties are appropriate for scaffolding other proteins in nodes.
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64
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Abstract
Formins polymerize actin filaments for the cytokinetic contractile ring. Using in vitro reconstitution of fission yeast contractile ring precursor nodes containing formins and myosin, a new study shows that formin-mediated polymerization is strongly inhibited upon the capture and pulling of actin filaments by myosin, a result that has broad implications for cellular mechanosensing.
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Affiliation(s)
| | - Brandon G Horan
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA
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65
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Mangione MC, Gould KL. Molecular form and function of the cytokinetic ring. J Cell Sci 2019; 132:132/12/jcs226928. [PMID: 31209062 DOI: 10.1242/jcs.226928] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Animal cells, amoebas and yeast divide using a force-generating, actin- and myosin-based contractile ring or 'cytokinetic ring' (CR). Despite intensive research, questions remain about the spatial organization of CR components, the mechanism by which the CR generates force, and how other cellular processes are coordinated with the CR for successful membrane ingression and ultimate cell separation. This Review highlights new findings about the spatial relationship of the CR to the plasma membrane and the arrangement of molecules within the CR from studies using advanced microscopy techniques, as well as mechanistic information obtained from in vitro approaches. We also consider advances in understanding coordinated cellular processes that impact the architecture and function of the CR.
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Affiliation(s)
- MariaSanta C Mangione
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
| | - Kathleen L Gould
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
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Morris Z, Sinha D, Poddar A, Morris B, Chen Q. Fission yeast TRP channel Pkd2p localizes to the cleavage furrow and regulates cell separation during cytokinesis. Mol Biol Cell 2019; 30:1791-1804. [PMID: 31116668 PMCID: PMC6727746 DOI: 10.1091/mbc.e18-04-0270] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Force plays a central role in separating daughter cells during cytokinesis, the last stage of cell division. However, the mechanism of force sensing during cytokinesis remains unknown. Here we discovered that Pkd2p, a putative force-sensing transient receptor potential channel, localizes to the cleavage furrow during cytokinesis of the fission yeast, Schizosaccharomyces pombe. Pkd2p, whose human homologues are associated with autosomal polycystic kidney disease, is an essential protein whose localization depends on the contractile ring and the secretory pathway. We identified and characterized a novel pkd2 mutant pkd2-81KD. The pkd2 mutant cells show signs of osmotic stress, including temporary shrinking, paused turnover of the cytoskeletal structures, and hyperactivated mitogen-activated protein kinase signaling. During cytokinesis, although the contractile ring constricts more rapidly in the pkd2 mutant than the wild-type cells (50% higher), the cell separation in the mutant is slower and often incomplete. These cytokinesis defects are also consistent with misregulated turgor pressure. Finally, the pkd2 mutant exhibits strong genetic interactions with two mutants of the septation initiation network pathway, a signaling cascade essential for cytokinesis. We propose that Pkd2p modulates osmotic homeostasis and is potentially a novel regulator of cytokinesis.
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Affiliation(s)
- Zachary Morris
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Debatrayee Sinha
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Abhishek Poddar
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Brittni Morris
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Qian Chen
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
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Okada H, Wloka C, Wu JQ, Bi E. Distinct Roles of Myosin-II Isoforms in Cytokinesis under Normal and Stressed Conditions. iScience 2019; 14:69-87. [PMID: 30928696 PMCID: PMC6441717 DOI: 10.1016/j.isci.2019.03.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 01/30/2019] [Accepted: 03/12/2019] [Indexed: 12/31/2022] Open
Abstract
To address the question of why more than one myosin-II isoform is expressed in a single cell to drive cytokinesis, we analyzed the roles of the myosin-II isoforms, Myo2 and Myp2, of the fission yeast Schizosaccharomyces pombe, in cytokinesis under normal and stressed conditions. We found that Myp2 controls the disassembly, stability, and constriction initiation of the Myo2 ring in response to high-salt stress. A C-terminal coiled-coil domain of Myp2 is required for its immobility and contractility during cytokinesis, and when fused to the tail of the dynamic Myo2, renders the chimera the low-turnover property. We also found, by following distinct processes in real time at the single-cell level, that Myo2 and Myp2 are differentially required but collectively essential for guiding extracellular matrix remodeling during cytokinesis. These results suggest that the dynamic and immobile myosin-II isoforms are evolved to carry out cytokinesis with robustness under different growth conditions. The myosin-II isoforms Myo2 and Myp2 display distinct responses to cellular stress Myp2 controls the constriction initiation of Myo2 during stress response A C-terminal region of Myp2 is required for its immobility during cytokinesis Myo2 and Myp2 are differentially required for guiding ECM remodeling during cytokinesis
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Affiliation(s)
- Hiroki Okada
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Carsten Wloka
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA; Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AE Groningen, The Netherlands
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Erfei Bi
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA.
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Onwubiko UN, Mlynarczyk PJ, Wei B, Habiyaremye J, Clack A, Abel SM, Das ME. A Cdc42 GEF, Gef1, through endocytosis organizes F-BAR Cdc15 along the actomyosin ring and promotes concentric furrowing. J Cell Sci 2019; 132:jcs223776. [PMID: 30709916 PMCID: PMC6432710 DOI: 10.1242/jcs.223776] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 01/21/2019] [Indexed: 01/17/2023] Open
Abstract
During cytokinesis, fission yeast coordinates actomyosin ring constriction with septum ingression, resulting in concentric furrow formation by a poorly defined mechanism. We report that Schizosaccharomyces pombe cells lacking the Cdc42 activator Gef1, combined with an activated allele of the formin, Cdc12, display non-concentric furrowing. Non-concentrically furrowing cells display uneven distribution of the scaffold Cdc15 along the ring. This suggests that, after ring assembly, uniform Cdc15 distribution along the ring enables proper furrow formation. We find that, after assembly, Cdc15 is recruited to the ring in an Arp2/3 complex-dependent manner and is decreased in the activated cdc12 mutant. Cdc15 at cortical endocytic patches shows increased levels and extended lifetimes in gef1 and activated cdc12 mutants. We hypothesize endocytosis helps recruit Cdc15 to assembled rings; uneven Cdc15 distribution at the ring occurs when endocytic patches contain increased Cdc15 levels and the patch-association rate is slow. Based on this, we developed a mathematical model that captures experimentally observed Cdc15 distributions along the ring. We propose that, at the ring, Gef1 and endocytic events promote uniform Cdc15 organization to enable proper septum ingression and concentric furrow formation.
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Affiliation(s)
- Udo N Onwubiko
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Paul J Mlynarczyk
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Bin Wei
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Julius Habiyaremye
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Amanda Clack
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Steven M Abel
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Maitreyi E Das
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
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Mazaheri M, Heckwolf M, Vaillancourt B, Gage JL, Burdo B, Heckwolf S, Barry K, Lipzen A, Ribeiro CB, Kono TJY, Kaeppler HF, Spalding EP, Hirsch CN, Robin Buell C, de Leon N, Kaeppler SM. Genome-wide association analysis of stalk biomass and anatomical traits in maize. BMC PLANT BIOLOGY 2019; 19:45. [PMID: 30704393 PMCID: PMC6357476 DOI: 10.1186/s12870-019-1653-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 01/14/2019] [Indexed: 05/22/2023]
Abstract
BACKGROUND Maize stover is an important source of crop residues and a promising sustainable energy source in the United States. Stalk is the main component of stover, representing about half of stover dry weight. Characterization of genetic determinants of stalk traits provide a foundation to optimize maize stover as a biofuel feedstock. We investigated maize natural genetic variation in genome-wide association studies (GWAS) to detect candidate genes associated with traits related to stalk biomass (stalk diameter and plant height) and stalk anatomy (rind thickness, vascular bundle density and area). RESULTS Using a panel of 942 diverse inbred lines, 899,784 RNA-Seq derived single nucleotide polymorphism (SNP) markers were identified. Stalk traits were measured on 800 members of the panel in replicated field trials across years. GWAS revealed 16 candidate genes associated with four stalk traits. Most of the detected candidate genes were involved in fundamental cellular functions, such as regulation of gene expression and cell cycle progression. Two of the regulatory genes (Zmm22 and an ortholog of Fpa) that were associated with plant height were previously shown to be involved in regulating the vegetative to floral transition. The association of Zmm22 with plant height was confirmed using a transgenic approach. Transgenic lines with increased expression of Zmm22 showed a significant decrease in plant height as well as tassel branch number, indicating a pleiotropic effect of Zmm22. CONCLUSION Substantial heritable variation was observed in the association panel for stalk traits, indicating a large potential for improving useful stalk traits in breeding programs. Genome-wide association analyses detected several candidate genes associated with multiple traits, suggesting common regulatory elements underlie various stalk traits. Results of this study provide insights into the genetic control of maize stalk anatomy and biomass.
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Affiliation(s)
- Mona Mazaheri
- Department of Agronomy, University of Wisconsin, Madison, WI 53706 USA
- Department of Energy, Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, WI 53706 USA
| | - Marlies Heckwolf
- Department of Agronomy, University of Wisconsin, Madison, WI 53706 USA
- Department of Energy, Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, WI 53706 USA
| | - Brieanne Vaillancourt
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824 USA
- Department of Energy, Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824 USA
| | - Joseph L. Gage
- Department of Agronomy, University of Wisconsin, Madison, WI 53706 USA
| | - Brett Burdo
- Department of Agronomy, University of Wisconsin, Madison, WI 53706 USA
| | - Sven Heckwolf
- Department of Botany, University of Wisconsin, Madison, WI 53706 USA
| | - Kerrie Barry
- Department of Energy, Joint Genome Institute, Walnut Creek, California, 94598 USA
| | - Anna Lipzen
- Department of Energy, Joint Genome Institute, Walnut Creek, California, 94598 USA
| | - Camila Bastos Ribeiro
- Genótika Super Sementes. Colonizador Ênio Pipino - St. Industrial Sul, Sinop, MT 78550-098 Brazil
| | - Thomas J. Y. Kono
- Department of Agronomy and Plant Genetics, University of Minnesota, 1991 Upper Buford Circle, St Paul, MN 55108 USA
- Present address: Minnesota Supercomputing Institute, 117 Pleasant Street SE, Minneapolis, MN 55455 USA
| | - Heidi F. Kaeppler
- Department of Agronomy, University of Wisconsin, Madison, WI 53706 USA
- Department of Energy, Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, WI 53706 USA
| | - Edgar P. Spalding
- Department of Botany, University of Wisconsin, Madison, WI 53706 USA
| | - Candice N. Hirsch
- Department of Agronomy and Plant Genetics, University of Minnesota, 1991 Upper Buford Circle, St Paul, MN 55108 USA
| | - C. Robin Buell
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824 USA
- Department of Energy, Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824 USA
- Plant Resilience Institute, Michigan State University, East Lansing, MI 48824 USA
| | - Natalia de Leon
- Department of Agronomy, University of Wisconsin, Madison, WI 53706 USA
- Department of Energy, Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, WI 53706 USA
| | - Shawn M. Kaeppler
- Department of Agronomy, University of Wisconsin, Madison, WI 53706 USA
- Department of Energy, Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, WI 53706 USA
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Kwon L, Magee EM, Crayton A, Goss JW. Fission yeast type 2 node proteins Blt1p and Gef2p cooperate to ensure timely completion of cytokinesis. BMC Mol Cell Biol 2019; 20:1. [PMID: 31041892 PMCID: PMC6446504 DOI: 10.1186/s12860-018-0182-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 12/14/2018] [Indexed: 12/01/2022] Open
Abstract
Background The conserved NDR-family kinase Sid2p localizes to the contractile ring during fission yeast cytokinesis to promote ring constriction, septation, and completion of cell division. Previous studies have found that the Type 2 interphase node proteins Blt1p and Gef2p contribute to localization of Sid2p and its regulatory protein Mob1p at the division site. However, their relative contributions and whether they operate in the same or parallel pathways has been unclear. In this study, we quantify the respective roles of Blt1p and Gef2p in Sid2p/Mob1p recruitment and characterize the effect of single and double deletion mutants on contractile ring dynamics and completion of cell division. Results Using quantitative confocal fluorescence microscopy, we measured Sid2p and Mob1p recruitment to the division site in blt1∆, gef2∆, and blt1∆/gef2∆ mutant cells. We observed an equivalent decrease in Sid2p/Mob1p localization for both single and double mutants. Though assembly of the contractile ring is normal in these mutants, the reduction in Sid2p/Mob1p at the division site delayed the onset of contractile ring constriction and completion of division. We quantified localization of Blt1p and Gef2p at the medial cortex throughout the cell cycle and found that Blt1p localization to interphase nodes and the contractile ring is independent of Gef2p. However, Gef2p localization to the contractile ring is decreased in blt1∆ mutants. Conclusions Blt1p and Gef2p work in the same pathway, rather than in parallel, to localize the NDR-family kinase Sid2p and its regulatory partner Mob1p to the division site, thereby promoting timely completion of cell division. Future studies are necessary to understand how additional fission yeast cytokinesis proteins work with these Type 2 interphase node components to promote Sid2p/Mob1p recruitment. Electronic supplementary material The online version of this article (10.1186/s12860-018-0182-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lois Kwon
- Department of Biological Sciences, Wellesley College, 106 Central Street, Wellesley, MA, 02481, USA
| | - Emma M Magee
- Department of Biological Sciences, Wellesley College, 106 Central Street, Wellesley, MA, 02481, USA
| | - Alexis Crayton
- Department of Biological Sciences, Wellesley College, 106 Central Street, Wellesley, MA, 02481, USA
| | - John W Goss
- Department of Biological Sciences, Wellesley College, 106 Central Street, Wellesley, MA, 02481, USA.
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Zimmermann D, Kovar DR. Feeling the force: formin's role in mechanotransduction. Curr Opin Cell Biol 2019; 56:130-140. [PMID: 30639952 DOI: 10.1016/j.ceb.2018.12.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 12/13/2018] [Accepted: 12/16/2018] [Indexed: 11/15/2022]
Abstract
Fundamental cellular processes such as division, polarization, and motility require the tightly regulated spatial and temporal assembly and disassembly of the underlying actin cytoskeleton. The actin cytoskeleton has been long viewed as a central player facilitating diverse mechanotransduction pathways due to the notion that it is capable of receiving, processing, transmitting, and generating mechanical stresses. Recent work has begun to uncover the roles of mechanical stresses in modulating the activity of key regulatory actin-binding proteins and their interactions with actin filaments, thereby controlling the assembly (formin and Arp2/3 complex) and disassembly (ADF/Cofilin) of actin filament networks. In this review, we will focus on discussing the current molecular understanding of how members of the formin protein family sense and respond to forces and the potential implications for formin-mediated mechanotransduction in cells.
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Affiliation(s)
- Dennis Zimmermann
- Massachusetts Institute of Technology, David H. Koch Institute for Integrative Cancer Research, 77 Massachusetts Ave, 76-361F, Cambridge, MA 02139-4307, United States.
| | - David R Kovar
- The University of Chicago, Department of Molecular Genetics and Cell Biology, 90 E. 58th Street, CSLC 212, Chicago, IL 60637, United States.
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Cortes DB, Dawes A, Liu J, Nickaeen M, Strychalski W, Maddox AS. Unite to divide - how models and biological experimentation have come together to reveal mechanisms of cytokinesis. J Cell Sci 2018; 131:131/24/jcs203570. [PMID: 30563924 DOI: 10.1242/jcs.203570] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Cytokinesis is the fundamental and ancient cellular process by which one cell physically divides into two. Cytokinesis in animal and fungal cells is achieved by contraction of an actomyosin cytoskeletal ring assembled in the cell cortex, typically at the cell equator. Cytokinesis is essential for the development of fertilized eggs into multicellular organisms and for homeostatic replenishment of cells. Correct execution of cytokinesis is also necessary for genome stability and the evasion of diseases including cancer. Cytokinesis has fascinated scientists for well over a century, but its speed and dynamics make experiments challenging to perform and interpret. The presence of redundant mechanisms is also a challenge to understand cytokinesis, leaving many fundamental questions unresolved. For example, how does a disordered cytoskeletal network transform into a coherent ring? What are the long-distance effects of localized contractility? Here, we provide a general introduction to 'modeling for biologists', and review how agent-based modeling and continuum mechanics modeling have helped to address these questions.
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Affiliation(s)
- Daniel B Cortes
- Department of Biology, University of North Carolina at Chapel Hill, 407 Fordham Hall, Chapel Hill, NC 27599, USA
| | - Adriana Dawes
- Departments of Mathematics and of Molecular Genetics, The Ohio State University, 100 Math Tower, 231 West 18th Avenue, Columbus, OH 43210, USA
| | - Jian Liu
- National Heart, Lung and Blood Institute, Biochemistry and Biophysics Center, 50 South Drive, NIH, Bethesda, MD 20892, USA
| | - Masoud Nickaeen
- Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center, Department of Cell Biology, 263 Farmington Avenue, Farmington, CT 06030-6406, USA
| | - Wanda Strychalski
- Department of Mathematics, Applied Mathematics, and Statistics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Amy Shaub Maddox
- Department of Biology, University of North Carolina at Chapel Hill, 407 Fordham Hall, Chapel Hill, NC 27599, USA
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Pollard TD. Evolution of research on cellular motility over five decades. Biophys Rev 2018; 10:1503-1508. [PMID: 30377975 PMCID: PMC6297086 DOI: 10.1007/s12551-018-0473-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 10/21/2018] [Indexed: 12/13/2022] Open
Abstract
This short review traces how our knowledge of the molecular mechanisms of cellular movements originated and developed over the past 50 years. Work on actin-based and microtubule-based movements developed in different ways, but in both fields, the discovery of the key proteins drove progress. Starting from an inventory of zero molecules in 1960, both fields matured spectacularly, so we now know the atomic structures of the important proteins, understand the kinetics and thermodynamics of their interactions, have documented how the molecules behave in cells, and can test theories with molecularly explicit computer simulations of cellular processes.
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Affiliation(s)
- Thomas D Pollard
- Departments of Molecular Cellular and Developmental Biology, Yale University, PO Box 208103, New Haven, CT, 06520-8103, USA.
- Departments of Molecular Biophysics and Biochemistry, Yale University, PO Box 208103, New Haven, CT, 06520-8103, USA.
- Department of Cell Biology, Yale University, PO Box 208103, New Haven, CT, 06520-8103, USA.
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O’Shaughnessy B, Thiyagarajan S. Mechanisms of contractile ring tension production and constriction. Biophys Rev 2018; 10:1667-1681. [PMID: 30456601 PMCID: PMC6297097 DOI: 10.1007/s12551-018-0476-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 10/23/2018] [Indexed: 12/24/2022] Open
Abstract
The contractile ring is a remarkable tension-generating cellular machine that constricts and divides cells into two during cytokinesis, the final stage of the cell cycle. Since the ring's discovery, the parallels with muscle have been emphasized. Both are contractile actomyosin machineries, and long ago, a muscle-like sliding filament mechanism was proposed for the ring. This review focuses on the mechanisms that generate ring tension and constrict contractile rings. The emphasis is on fission yeast, whose contractile ring is sufficiently well characterized that realistic mathematical models are feasible, and possible lessons from fission yeast that may apply to animal cells are discussed. Recent discoveries relevant to the organization in fission yeast rings suggest a stochastic steady-state version of the classic sliding filament mechanism for tension. The importance of different modes of anchoring for tension production and for organizational stability of constricting rings is discussed. Possible mechanisms are discussed that set the constriction rate and enable the contractile ring to meet the technical challenge of maintaining structural integrity and tension-generating capacity while continuously disassembling throughout constriction.
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Affiliation(s)
- Ben O’Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, NY 10027 USA
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75
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Abstract
During cytokinesis, the cell employs various molecular machineries to separate into two daughters. Many signaling pathways are required to ensure temporal and spatial coordination of the molecular and mechanical events. Cells can also coordinate division with neighboring cells to maintain tissue integrity and flexibility. In this review, we focus on recent advances in the understanding of the molecular underpinnings of cytokinesis.
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Affiliation(s)
- Yinan Liu
- Departments of Cell Biology and Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205, USA
| | - Douglas Robinson
- Departments of Cell Biology and Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205, USA
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Laplante C. Building the contractile ring from the ground up: a lesson in perseverance and scientific creativity. Biophys Rev 2018; 10:1491-1497. [PMID: 30448942 DOI: 10.1007/s12551-018-0482-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Accepted: 11/08/2018] [Indexed: 11/28/2022] Open
Abstract
This contribution to the Festschrift for Professor Thomas (Tom) D. Pollard focuses on his work on the elucidation of the protein organization within the cytokinetic nodes, protein assemblies, precursors to the contractile ring. In particular, this work highlights recent discoveries in the molecular organization of the proteins that make the contractile machine in fission yeast using advanced microscopy techniques. One of the main aspects of Tom's research philosophy that marked my career as one of his trainees is his embrace of interdisciplinary approaches to research. The cost of interdisciplinary research is to be willing to step out of our technical comfort zone to learn a new set of tools. The payoff of interdisciplinary research is the expansion our realm of possibilities by bringing new creative tools and ideas to push our research program forward. The rewarding outcomes of this work under Tom's mentorship were the molecular model of the cytokinetic node and the development of new techniques to unravel the structure of multi-protein complexes in live cells. Together, these findings open a new set of questions about the mechanism of cytokinesis and provide creative tools to address them.
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Affiliation(s)
- Caroline Laplante
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, 1051 William Moore Drive, Office: RB 254, Raleigh, NC, 27606, USA.
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77
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Molecular mechanisms of contractile-ring constriction and membrane trafficking in cytokinesis. Biophys Rev 2018; 10:1649-1666. [PMID: 30448943 DOI: 10.1007/s12551-018-0479-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 11/06/2018] [Indexed: 12/14/2022] Open
Abstract
In this review, we discuss the molecular mechanisms of cytokinesis from plants to humans, with a focus on contribution of membrane trafficking to cytokinesis. Selection of the division site in fungi, metazoans, and plants is reviewed, as well as the assembly and constriction of a contractile ring in fungi and metazoans. We also provide an introduction to exocytosis and endocytosis, and discuss how they contribute to successful cytokinesis in eukaryotic cells. The conservation in the coordination of membrane deposition and cytoskeleton during cytokinesis in fungi, metazoans, and plants is highlighted.
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78
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Zach R, Převorovský M. The phenomenon of lipid metabolism "cut" mutants. Yeast 2018; 35:631-637. [PMID: 30278108 DOI: 10.1002/yea.3358] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 09/06/2018] [Accepted: 09/24/2018] [Indexed: 02/05/2023] Open
Abstract
Every cell cycle iteration culminates with the resolution of a mitotic nucleus into a pair of daughter nuclei, which are distributed between the two daughter cells. In the fission yeast Schizosaccharomyces pombe, the faithful division of a mitotic nucleus depends on unperturbed lipogenesis. Upon genetically or chemically induced perturbation of lipid anabolism, S. pombe cells fail to separate the two daughter nuclei and subsequently initiate lethal cytokinesis resulting in the so-called "cut" terminal phenotype. Evidence supporting a critical role of lipid biogenesis in successful mitosis in S. pombe has been accumulating for almost two decades, but the exact mechanism explaining the reported observations had been elusive. Recently, several studies established a functional link between biosynthesis of structural phospholipids, nuclear membrane growth, and the fidelity of "closed" mitosis in S. pombe. These novel insights suggest a mechanistic explanation for the mitotic defects characteristic for some S. pombe mutants deficient in lipid anabolism and extend our knowledge of metabolic modulation within the context of the cell cycle. In this review, we cover the essential role of lipogenesis in "closed" mitosis, focusing mainly on S. pombe as a model system.
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Affiliation(s)
- Róbert Zach
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic.,Genome Damage and Stability Centre, University of Sussex, Brighton, UK
| | - Martin Převorovský
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
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Structural evidence for the roles of divalent cations in actin polymerization and activation of ATP hydrolysis. Proc Natl Acad Sci U S A 2018; 115:10345-10350. [PMID: 30254171 PMCID: PMC6187199 DOI: 10.1073/pnas.1806394115] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Actin polymerization is a divalent cation-dependent process. Here we identify a cation binding site on the surface of actin in a 2.0-Å resolution X-ray structure of actin and find evidence of three additional sites in published high-resolution structures. These cations are stable in molecular dynamics (MD) simulations of the filament, suggesting a functional role in polymerization or filament rigidity. Polymerization activates the ATPase activity of the incorporating actin protomers. Careful analysis of water molecules that approach the ATP in the MD simulations revealed Gln137-activated water to be in a suitable position in F-actin, to initiate attack for ATP hydrolysis, and its occupancy was dependent on bound cations. The structure of the actin filament is known at a resolution that has allowed the architecture of protein components to be unambiguously assigned. However, fully understanding the chemistry of the system requires higher resolution to identify the ions and water molecules involved in polymerization and ATP hydrolysis. Here, we find experimental evidence for the association of cations with the surfaces of G-actin in a 2.0-Å resolution X-ray structure of actin bound to a Cordon-Bleu WH2 motif and in previously determined high-resolution X-ray structures. Three of four reoccurring divalent cation sites were stable during molecular dynamics (MD) simulations of the filament, suggesting that these sites may play a functional role in stabilizing the filament. We modeled the water coordination at the ATP-bound Mg2+, which also proved to be stable during the MD simulations. Using this model of the filament with a hydrated ATP-bound Mg2+, we compared the cumulative probability of an activated hydrolytic water molecule approaching the γ-phosphorous of ATP, in comparison with G-actin, in the MD simulations. The cumulative probability increased in F-actin in line with the activation of actin’s ATPase activity on polymerization. However, inclusion of the cations in the filament lowered cumulative probability, suggesting the rate of hydrolysis may be linked to filament flexibility. Together, these data extend the possible roles of Mg2+ in polymerization and the mechanism of polymerization-induced activation of actin’s ATPase activity.
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80
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Biocompatible PEGylated Gold nanorods function As cytokinesis inhibitors to suppress angiogenesis. Biomaterials 2018; 178:23-35. [DOI: 10.1016/j.biomaterials.2018.06.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/16/2018] [Accepted: 06/06/2018] [Indexed: 12/17/2022]
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81
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Zhou Q, An T, Pham KTM, Hu H, Li Z. The CIF1 protein is a master orchestrator of trypanosome cytokinesis that recruits several cytokinesis regulators to the cytokinesis initiation site. J Biol Chem 2018; 293:16177-16192. [PMID: 30171070 DOI: 10.1074/jbc.ra118.004888] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 08/28/2018] [Indexed: 12/13/2022] Open
Abstract
To proliferate, the parasitic protozoan Trypanosoma brucei undergoes binary fission in a unidirectional manner along the cell's longitudinal axis from the cell anterior toward the cell posterior. This unusual mode of cell division is controlled by a regulatory pathway composed of two evolutionarily conserved protein kinases, Polo-like kinase and Aurora B kinase, and three trypanosome-specific proteins, CIF1, CIF2, and CIF3, which act in concert at the cytokinesis initiation site located at the distal tip of the newly assembled flagellum attachment zone (FAZ). However, additional regulators that function in this cytokinesis signaling cascade remain to be identified and characterized. Using proximity biotinylation, co-immunofluorescence microscopy, and co-immunoprecipitation, we identified 52 CIF1-associated proteins and validated six CIF1-interacting proteins, including the putative protein phosphatase KPP1, the katanin p80 subunit KAT80, the cleavage furrow-localized proteins KLIF and FRW1, and the FAZ tip-localized proteins FAZ20 and FPRC. Further analyses of the functional interplay between CIF1 and its associated proteins revealed a requirement of CIF1 for localization of a set of CIF1-associated proteins, an interdependence between KPP1 and CIF1, and an essential role of katanin in the completion of cleavage furrow ingression. Together, these results suggest that CIF1 acts as a master regulator of cytokinesis in T. brucei by recruiting a cohort of cytokinesis regulatory proteins to the cytokinesis initiation site.
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Affiliation(s)
- Qing Zhou
- From the Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Tai An
- From the Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Kieu T M Pham
- From the Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Huiqing Hu
- From the Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Ziyin Li
- From the Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030
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82
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Dey SK, Pollard TD. Involvement of the septation initiation network in events during cytokinesis in fission yeast. J Cell Sci 2018; 131:jcs.216895. [PMID: 30072443 DOI: 10.1242/jcs.216895] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 07/23/2018] [Indexed: 10/28/2022] Open
Abstract
The septation initiation network (SIN), comprising a GTPase and a cascade of three protein kinases, regulates cell division in fission yeast Schizosaccharomyces pombe, but questions remain about its influence on cytokinesis. Here, we made quantitative measurements of the numbers of Cdc7p kinase molecules (a marker for SIN activity) on spindle pole bodies (SPBs), and on the timing of assembly, maturation and constriction of contractile rings via six different proteins tagged with fluorescent proteins. When SIN activity is low in spg1-106 mutant cells at 32°C, cytokinetic nodes formed contractile rings ∼3 min slower than wild-type cells. During the maturation period, these rings maintained normal levels of the myosin-II mEGFP-Myo2p but accumulated less of the F-BAR protein Cdc15p-GFP than in wild-type cells. The Cdc15p-GFP fluorescence then disintegrated into spots as mEGFP-Myo2p dissociated slowly. Some rings started to constrict at the normal time, but most failed to complete constriction. When high SIN activity persists far longer than normal on both SPBs in cdc16-116 mutant cells at 32°C, contractile rings assembled and constricted normally, but disassembled slowly, delaying cell separation.
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Affiliation(s)
- Sumit K Dey
- Department of Molecular Cellular and Developmental Biology, Yale University, PO Box 208103, New Haven, CT 06520-8103, USA
| | - Thomas D Pollard
- Department of Molecular Cellular and Developmental Biology, Yale University, PO Box 208103, New Haven, CT 06520-8103, USA .,Department of Molecular Biophysics and Biochemistry, Yale University, PO Box 208103, New Haven, CT 06520-8103, USA.,Department of Cell Biology, Yale University, PO Box 208103, New Haven, CT 06520-8103, USA
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83
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Zhu YH, Hyun J, Pan YZ, Hopper JE, Rizo J, Wu JQ. Roles of the fission yeast UNC-13/Munc13 protein Ync13 in late stages of cytokinesis. Mol Biol Cell 2018; 29:2259-2279. [PMID: 30044717 PMCID: PMC6249806 DOI: 10.1091/mbc.e18-04-0225] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cytokinesis is a complicated yet conserved step of the cell-division cycle that requires the coordination of multiple proteins and cellular processes. Here we describe a previously uncharacterized protein, Ync13, and its roles during fission yeast cytokinesis. Ync13 is a member of the UNC-13/Munc13 protein family, whose animal homologues are essential priming factors for soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex assembly during exocytosis in various cell types, but no roles in cytokinesis have been reported. We find that Ync13 binds to lipids in vitro and dynamically localizes to the plasma membrane at cell tips during interphase and at the division site during cytokinesis. Deletion of Ync13 leads to defective septation and exocytosis, uneven distribution of cell-wall enzymes and components of cell-wall integrity pathway along the division site and massive cell lysis during cell separation. Interestingly, loss of Ync13 compromises endocytic site selection at the division plane. Collectively, we find that Ync13 has a novel function as an UNC-13/Munc13 protein in coordinating exocytosis, endocytosis, and cell-wall integrity during fission yeast cytokinesis.
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Affiliation(s)
- Yi-Hua Zhu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Joanne Hyun
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Yun-Zu Pan
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - James E Hopper
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
| | - Josep Rizo
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210.,Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210
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84
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Jacquet K, Banerjee SL, Chartier FJM, Elowe S, Bisson N. Proteomic Analysis of NCK1/2 Adaptors Uncovers Paralog-specific Interactions That Reveal a New Role for NCK2 in Cell Abscission During Cytokinesis. Mol Cell Proteomics 2018; 17:1979-1990. [PMID: 30002203 DOI: 10.1074/mcp.ra118.000689] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 07/11/2018] [Indexed: 12/31/2022] Open
Abstract
Signals from cell surface receptors are often relayed via adaptor proteins. NCK1 and NCK2 are Src-Homology (SH) 2 and 3 domain adaptors that regulate processes requiring a remodeling of the actin cytoskeleton. Evidence from gene inactivation in mouse suggests that NCK1 and NCK2 are functionally redundant, although recent reports support the idea of unique functions for NCK1 and NCK2. We sought to examine this question further by delineating NCK1- and NCK2-specific signaling networks. We used both affinity purification-mass spectrometry and BioID proximity labeling to identify NCK1/2 signaling networks comprised of 98 proteins. Strikingly, we found 30 proteins restricted to NCK1 and 28 proteins specifically associated with NCK2, suggesting differences in their function. We report that Nck2 -/-, but not Nck1 -/- mouse embryo fibroblasts (MEFs) are multinucleated and display extended protrusions reminiscent of intercellular bridges, which correlate with an extended time spent in cytokinesis as well as a failure of a significant proportion of cells to complete abscission. Our data also show that the midbody of NCK2-deficient cells is not only increased in length, but also altered in composition, as judged by the mislocalization of AURKB, PLK1 and ECT2. Finally, we show that NCK2 function during cytokinesis requires its SH2 domain. Taken together, our data delineate the first high-confidence interactome for NCK1/2 adaptors and highlight several proteins specifically associated with either protein. Thus, contrary to what is generally accepted, we demonstrate that NCK1 and NCK2 are not completely redundant, and shed light on a previously uncharacterized function for the NCK2 adaptor protein in cell division.
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Affiliation(s)
- Kévin Jacquet
- From the ‡Centre de recherche du Centre Hospitalier Universitaire (CHU) de Québec-Université Laval, Axe Oncologie, Québec G1R 2J6, QC, Canada.,§Centre de recherche sur le cancer de l'Université Laval, Québec G1R 2J6, QC, Canada.,¶PROTEO-Quebec Network for Research on Protein Function, Engineering, and Applications, Québec G1V 0A6, QC, Canada
| | - Sara L Banerjee
- From the ‡Centre de recherche du Centre Hospitalier Universitaire (CHU) de Québec-Université Laval, Axe Oncologie, Québec G1R 2J6, QC, Canada.,§Centre de recherche sur le cancer de l'Université Laval, Québec G1R 2J6, QC, Canada.,¶PROTEO-Quebec Network for Research on Protein Function, Engineering, and Applications, Québec G1V 0A6, QC, Canada
| | - François J M Chartier
- From the ‡Centre de recherche du Centre Hospitalier Universitaire (CHU) de Québec-Université Laval, Axe Oncologie, Québec G1R 2J6, QC, Canada.,§Centre de recherche sur le cancer de l'Université Laval, Québec G1R 2J6, QC, Canada.,¶PROTEO-Quebec Network for Research on Protein Function, Engineering, and Applications, Québec G1V 0A6, QC, Canada
| | - Sabine Elowe
- §Centre de recherche sur le cancer de l'Université Laval, Québec G1R 2J6, QC, Canada.,¶PROTEO-Quebec Network for Research on Protein Function, Engineering, and Applications, Québec G1V 0A6, QC, Canada.,‖Centre de recherche du Centre Hospitalier Universitaire (CHU) de Québec-Université Laval, Axe Reproduction, santé de la mère et de l'enfant, Québec G1V 4G2, QC, Canada.,**Department of Pediatrics, Université Laval, Québec, QC, Canada
| | - Nicolas Bisson
- From the ‡Centre de recherche du Centre Hospitalier Universitaire (CHU) de Québec-Université Laval, Axe Oncologie, Québec G1R 2J6, QC, Canada; .,§Centre de recherche sur le cancer de l'Université Laval, Québec G1R 2J6, QC, Canada.,¶PROTEO-Quebec Network for Research on Protein Function, Engineering, and Applications, Québec G1V 0A6, QC, Canada.,‡‡Department of Molecular Biology, Medical Biochemistry and Pathology, Université Laval, Québec G1V 0A6, QC, Canada
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85
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G. Cortés JC, Ramos M, Konomi M, Barragán I, Moreno MB, Alcaide-Gavilán M, Moreno S, Osumi M, Pérez P, Ribas JC. Specific detection of fission yeast primary septum reveals septum and cleavage furrow ingression during early anaphase independent of mitosis completion. PLoS Genet 2018; 14:e1007388. [PMID: 29813053 PMCID: PMC5993333 DOI: 10.1371/journal.pgen.1007388] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 06/08/2018] [Accepted: 05/01/2018] [Indexed: 11/27/2022] Open
Abstract
It is widely accepted in eukaryotes that the cleavage furrow only initiates after mitosis completion. In fission yeast, cytokinesis requires the synthesis of a septum tightly coupled to cleavage furrow ingression. The current cytokinesis model establishes that simultaneous septation and furrow ingression only initiate after spindle breakage and mitosis exit. Thus, this model considers that although Cdk1 is inactivated at early-anaphase, septation onset requires the long elapsed time until mitosis completion and full activation of the Hippo-like SIN pathway. Here, we studied the precise timing of septation onset regarding mitosis by exploiting both the septum-specific detection with the fluorochrome calcofluor and the high-resolution electron microscopy during anaphase and telophase. Contrarily to the existing model, we found that both septum and cleavage furrow start to ingress at early anaphase B, long before spindle breakage, with a slow ingression rate during anaphase B, and greatly increasing after telophase onset. This shows that mitosis and cleavage furrow ingression are not concatenated but simultaneous events in fission yeast. We found that the timing of septation during early anaphase correlates with the cell size and is regulated by the corresponding levels of SIN Etd1 and Rho1. Cdk1 inactivation was directly required for timely septation in early anaphase. Strikingly the reduced SIN activity present after Cdk1 loss was enough to trigger septation by immediately inducing the medial recruitment of the SIN kinase complex Sid2-Mob1. On the other hand, septation onset did not depend on the SIN asymmetry establishment, which is considered a hallmark for SIN activation. These results recalibrate the timing of key cytokinetic events in fission yeast; and unveil a size-dependent control mechanism that synchronizes simultaneous nuclei separation with septum and cleavage furrow ingression to safeguard the proper chromosome segregation during cell division. Fission yeast cytokinesis requires the invagination of the equatorial plasma membrane (cleavage furrow ingression) coupled to the synthesis of a special wall structure named septum (septation). Despite Cdk1 kinase is inactivated in early anaphase, it is believed that cleavage furrow ingression and septation onset require anaphase progression and mitosis completion, only initiating after the complete activation of the Hippo-like septation initiation network (SIN) after telophase onset. Here, we studied the precise timing of septation start with respect to mitosis through specific septum-staining and electron microscopy. We found that septum and cleavage furrow ingression initiate in early anaphase, showing first a slow ingression rate during anaphase B, and increasing to a fast ingression rate after telophase onset. Thus, mitosis and cleavage furrow ingression are not concatenated but simultaneous events in fission yeast. The timing of septation correlated with cell size and depended on the level of cytoplasmic activators like SIN Etd1 and Rho1. We further analyzed the mitotic mechanisms that control the septation onset during early anaphase. Cdk1 directly regulated the timing of septation onset during early anaphase, and the low SIN activity present after Cdk1 inactivation was enough to trigger septation. Globally, these results recalibrate the timing of the main cytokinetic events of fission yeast and reveal a size-dependent control mechanism that synchronizes simultaneous nuclei separation with septum and cleavage furrow ingression.
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Affiliation(s)
- Juan Carlos G. Cortés
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
- * E-mail:
| | - Mariona Ramos
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
| | - Mami Konomi
- Laboratory of Electron Microscopy/Bio-imaging Centre, and Department of Chemical and Biological Sciences, Japan Women's University, Mejirodai, Bunkyo-ku, Tokyo, Japan
| | - Iris Barragán
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
| | - M. Belén Moreno
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
| | - María Alcaide-Gavilán
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide/Consejo Superior de Investigaciones Científicas, Sevilla, Spain
| | - Sergio Moreno
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
| | - Masako Osumi
- Laboratory of Electron Microscopy/Bio-imaging Centre, and Department of Chemical and Biological Sciences, Japan Women's University, Mejirodai, Bunkyo-ku, Tokyo, Japan
- NPO: Integrated Imaging Research Support, Hirakawa-cho, Chiyoda-ku, Tokyo, Japan
| | - Pilar Pérez
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
| | - Juan Carlos Ribas
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, Salamanca, Spain
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86
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Zheng S, Dong F, Rasul F, Yao X, Jin QW, Zheng F, Fu C. Septins regulate the equatorial dynamics of the separation initiation network kinase Sid2p and glucan synthases to ensure proper cytokinesis. FEBS J 2018; 285:2468-2480. [PMID: 29722930 DOI: 10.1111/febs.14487] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/18/2018] [Accepted: 04/24/2018] [Indexed: 12/31/2022]
Abstract
Septins generally function as scaffolds and as cortical barriers to restrict the diffusion of membrane proteins. In the fission yeast Schizosaccharomyces pombe, septins form a ring structure at the septum after spindle breakdown during the constriction of the contractile actomyosin ring (CAR) and serve as a scaffold to recruit glucanases to mediate ultimate daughter cell separation. Despite this, it remains unclear if septins play any significant roles before the cell separation during cytokinesis. Employing live cell microscopy, we carefully examined SIN (Septation Initiation Network) signaling and glucan synthases, two key factors ensuring proper function of the CAR. In the absence of the core septin component Spn1p, the formation of a compact CAR is advanced and the CAR constriction rate is slightly but significantly decreased. Moreover, the SIN kinase Sid2p and the glucan synthases Bgs1p and Ags1p form an equatorial ring quite prematurely, but their maintenance at the equatorial region is diminished spn1Δ cells. These findings suggest that septins act as key players in an accurate establishment and the maintenance of CAR by orchestrating the equatorial dynamics of Sid2p and glucan synthases. Hence, this work demonstrates that, in addition to their function during ultimate cell septation, septins have important roles in regulating earlier cytokinetic events, including CAR assembly and constriction, SIN signaling, and the cortical dynamics of the glucan synthases.
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Affiliation(s)
- Shengnan Zheng
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.,Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, University of Science and Technology of China, Hefei, Anhui, China
| | - Fenfen Dong
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.,Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, University of Science and Technology of China, Hefei, Anhui, China
| | - Faiz Rasul
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.,Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, University of Science and Technology of China, Hefei, Anhui, China
| | - Xuebiao Yao
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.,Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, University of Science and Technology of China, Hefei, Anhui, China
| | - Quan-Wen Jin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Fujian, China
| | - Fan Zheng
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.,Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, University of Science and Technology of China, Hefei, Anhui, China
| | - Chuanhai Fu
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.,Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, University of Science and Technology of China, Hefei, Anhui, China
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87
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Ma R, Berro J. Structural organization and energy storage in crosslinked actin assemblies. PLoS Comput Biol 2018; 14:e1006150. [PMID: 29813051 PMCID: PMC5993335 DOI: 10.1371/journal.pcbi.1006150] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 06/08/2018] [Accepted: 04/18/2018] [Indexed: 11/19/2022] Open
Abstract
During clathrin-mediated endocytosis in yeast cells, short actin filaments (< 200nm) and crosslinking protein fimbrin assemble to drive the internalization of the plasma membrane. However, the organization of the actin meshwork during endocytosis remains largely unknown. In addition, only a small fraction of the force necessary to elongate and pinch off vesicles can be accounted for by actin polymerization alone. In this paper, we used mathematical modeling to study the self-organization of rigid actin filaments in the presence of elastic crosslinkers in conditions relevant to endocytosis. We found that actin filaments condense into either a disordered meshwork or an ordered bundle depending on filament length and the mechanical and kinetic properties of the crosslinkers. Our simulations also demonstrated that these nanometer-scale actin structures can store a large amount of elastic energy within the crosslinkers (up to 10kBT per crosslinker). This conversion of binding energy into elastic energy is the consequence of geometric constraints created by the helical pitch of the actin filaments, which results in frustrated configurations of crosslinkers attached to filaments. We propose that this stored elastic energy can be used at a later time in the endocytic process. As a proof of principle, we presented a simple mechanism for sustained torque production by ordered detachment of crosslinkers from a pair of parallel filaments.
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Affiliation(s)
- Rui Ma
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
- Nanobiology Institute, Yale University, West Haven, Connecticut, United States of America
| | - Julien Berro
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
- Nanobiology Institute, Yale University, West Haven, Connecticut, United States of America
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, United States of America
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88
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Hatano T, Alioto S, Roscioli E, Palani S, Clarke ST, Kamnev A, Hernandez-Fernaud JR, Sivashanmugam L, Chapa-Y-Lazo B, Jones AME, Robinson RC, Sampath K, Mishima M, McAinsh AD, Goode BL, Balasubramanian MK. Rapid production of pure recombinant actin isoforms in Pichia pastoris. J Cell Sci 2018. [PMID: 29535210 PMCID: PMC5976186 DOI: 10.1242/jcs.213827] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Actins are major eukaryotic cytoskeletal proteins, and they are involved in many important cell functions, including cell division, cell polarity, wound healing and muscle contraction. Despite obvious drawbacks, muscle actin, which is easily purified, is used extensively for biochemical studies of the non-muscle actin cytoskeleton. Here, we report a rapid and cost-effective method to purify heterologous actins expressed in the yeast Pichia pastoris. Actin is expressed as a fusion with the actin-binding protein thymosin β4 and purified by means of an affinity tag introduced in the fusion. Following cleavage of thymosin β4 and the affinity tag, highly purified functional full-length actin is liberated. We purify actins from Saccharomycescerevisiae and Schizosaccharomycespombe, and the β- and γ-isoforms of human actin. We also report a modification of the method that facilitates expression and purification of arginylated actin, a form of actin thought to regulate dendritic actin networks in mammalian cells. The methods we describe can be performed in all laboratories equipped for molecular biology, and should greatly facilitate biochemical and cell biological studies of the actin cytoskeleton. Summary:Here, we describe a method to purify recombinant actin to homogeneity by expression in Pichia pastoris. The purified actin is polymerisation competent and should facilitate biochemical and cell biological studies of the actin cytoskeleton.
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Affiliation(s)
- Tomoyuki Hatano
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Salvatore Alioto
- Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Emanuele Roscioli
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Saravanan Palani
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Scott T Clarke
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Anton Kamnev
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | | | - Lavanya Sivashanmugam
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Bernardo Chapa-Y-Lazo
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | | | - Robert C Robinson
- Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology, and Research), Singapore 138673, Singapore.,Department of Biochemistry, National University of Singapore, Singapore 117597, Singapore.,Research Institute for Interdisciplinary Science, Okayama University, Okayama, 700-8530, Japan
| | - Karuna Sampath
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Masanori Mishima
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Andrew D McAinsh
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Bruce L Goode
- Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Mohan K Balasubramanian
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
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89
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Feng Z, Tian J, Han L, Geng Y, Sun J, Kong Z. The Myosin5-mediated actomyosin motility system is required for Verticillium
pathogenesis of cotton. Environ Microbiol 2018; 20:1607-1621. [DOI: 10.1111/1462-2920.14101] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 03/05/2018] [Accepted: 03/11/2018] [Indexed: 11/30/2022]
Affiliation(s)
- Zhidi Feng
- The Key Laboratory of Oasis Eco-Agriculture; College of Agriculture, Shihezi University; Shihezi Xinjiang 832000 China
- State Key Laboratory of Plant Genomic; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
| | - Juan Tian
- State Key Laboratory of Plant Genomic; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
| | - Libo Han
- State Key Laboratory of Plant Genomic; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
| | - Yuan Geng
- State Key Laboratory of Plant Genomic; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
| | - Jie Sun
- The Key Laboratory of Oasis Eco-Agriculture; College of Agriculture, Shihezi University; Shihezi Xinjiang 832000 China
| | - Zhaosheng Kong
- State Key Laboratory of Plant Genomic; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
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90
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Nguyen LT, Swulius MT, Aich S, Mishra M, Jensen GJ. Coarse-grained simulations of actomyosin rings point to a nodeless model involving both unipolar and bipolar myosins. Mol Biol Cell 2018; 29:1318-1331. [PMID: 29851561 PMCID: PMC5994903 DOI: 10.1091/mbc.e17-12-0736] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cytokinesis in many eukaryotic cells is orchestrated by a contractile actomyosin ring. While many of the proteins involved are known, the mechanism of constriction remains unclear. Informed by the existing literature and new three-dimensional (3D) molecular details from electron cryotomography, here we develop 3D coarse-grained models of actin filaments, unipolar and bipolar myosins, actin cross-linkers, and membranes and simulate their interactions. Assuming that local force on the membrane results in inward growth of the cell wall, we explored a matrix of possible actomyosin configurations and found that node-based architectures like those presently described for ring assembly result in membrane puckers not seen in electron microscope images of real cells. Instead, the model that best matches data from fluorescence microscopy, electron cryotomography, and biochemical experiments is one in which actin filaments transmit force to the membrane through evenly distributed, membrane-attached, unipolar myosins, with bipolar myosins in the ring driving contraction. While at this point this model is only favored (not proven), the work highlights the power of coarse-grained biophysical simulations to compare complex mechanistic hypotheses.
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Affiliation(s)
- Lam T Nguyen
- California Institute of Technology, Pasadena, CA 91125.,Howard Hughes Medical Institute, Chevy Chase, MD 20815
| | - Matthew T Swulius
- California Institute of Technology, Pasadena, CA 91125.,Howard Hughes Medical Institute, Chevy Chase, MD 20815
| | - Samya Aich
- Tata Institute of Fundamental Research, Mumbai 400005, India
| | | | - Grant J Jensen
- California Institute of Technology, Pasadena, CA 91125.,Howard Hughes Medical Institute, Chevy Chase, MD 20815
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91
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Wang M, Nishihama R, Onishi M, Pringle JR. Role of the Hof1-Cyk3 interaction in cleavage-furrow ingression and primary-septum formation during yeast cytokinesis. Mol Biol Cell 2018; 29:597-609. [PMID: 29321253 PMCID: PMC6004579 DOI: 10.1091/mbc.e17-04-0227] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 12/26/2017] [Accepted: 01/03/2018] [Indexed: 11/11/2022] Open
Abstract
In Saccharomyces cerevisiae, it is well established that Hof1, Cyk3, and Inn1 contribute to septum formation and cytokinesis. Because hof1∆ and cyk3∆ single mutants have relatively mild defects but hof1∆ cyk3∆ double mutants are nearly dead, it has been hypothesized that these proteins contribute to parallel pathways. However, there is also evidence that they interact physically. In this study, we examined this interaction and its functional significance in detail. Our data indicate that the interaction 1) is mediated by a direct binding of the Hof1 SH3 domain to a proline-rich motif in Cyk3; 2) occurs specifically at the time of cytokinesis but is independent of the (hyper)phosphorylation of both proteins that occurs at about the same time; 3) is dispensable for the normal localization of both proteins; 4) is essential for normal primary-septum formation and a normal rate of cleavage-furrow ingression; and 5) becomes critical for growth when either Inn1 or the type II myosin Myo1 (a key component of the contractile actomyosin ring) is absent. The similarity in phenotype between cyk3∆ mutants and mutants specifically lacking the Hof1-Cyk3 interaction suggests that the interaction is particularly important for Cyk3 function, but it may be important for Hof1 function as well.
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Affiliation(s)
- Meng Wang
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Ryuichi Nishihama
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Masayuki Onishi
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - John R Pringle
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
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92
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Laplante C. Resolving single-actin filaments within the contractile ring of fission yeast. Proc Natl Acad Sci U S A 2018; 115:1403-1405. [PMID: 29386379 PMCID: PMC5816221 DOI: 10.1073/pnas.1722624115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Caroline Laplante
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC 27606
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93
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Abstract
Cell division in many eukaryotes is driven by a ring containing actin and myosin. While much is known about the main proteins involved, the precise arrangement of actin filaments within the contractile machinery, and how force is transmitted to the membrane, remains unclear. Here we use cryosectioning and cryofocused ion beam milling to gain access to cryopreserved actomyosin rings in Schizosaccharomyces pombe for direct 3D imaging by electron cryotomography. Our results show that straight, overlapping actin filaments, running nearly parallel to each other and to the membrane, form a loose bundle of ∼150 nm in diameter that "saddles" the inward-bending membrane at the leading edge of the division septum. The filaments do not make direct contact with the membrane. Our analysis of the actin filaments reveals the variability in filament number, nearest-neighbor distances between filaments within the bundle, their distance from the membrane, and angular distribution with respect to the membrane.
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94
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Conti J, Viola MG, Camberg JL. FtsA reshapes membrane architecture and remodels the Z-ring in Escherichia coli. Mol Microbiol 2018; 107:558-576. [PMID: 29280220 DOI: 10.1111/mmi.13902] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 12/14/2017] [Accepted: 12/17/2017] [Indexed: 12/20/2022]
Abstract
Cell division in prokaryotes initiates with assembly of the Z-ring at midcell, which, in Escherichia coli, is tethered to the inner leaflet of the cytoplasmic membrane through a direct interaction with FtsA, a widely conserved actin homolog. The Z-ring is comprised of polymers of tubulin-like FtsZ and has been suggested to provide the force for constriction. Here, we demonstrate that FtsA exerts force on membranes causing redistribution of membrane architecture, robustly hydrolyzes ATP and directly engages FtsZ polymers in a reconstituted system. Phospholipid reorganization by FtsA occurs rapidly and is mediated by insertion of a C-terminal membrane targeting sequence (MTS) into the bilayer and further promoted by a nucleotide-dependent conformational change relayed to the MTS. FtsA also recruits FtsZ to phospholipid vesicles via a direct interaction with the FtsZ C-terminus and regulates FtsZ assembly kinetics. These results implicate the actin homolog FtsA in establishment of a Z-ring scaffold, while directly remodeling the membrane and provide mechanistic insight into localized cell wall remodeling, invagination and constriction at the onset of division.
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Affiliation(s)
| | | | - Jodi L Camberg
- Departments of Cell and Molecular Biology.,Nutrition and Food Sciences, The University of Rhode Island, Kingston, RI 02881, USA
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95
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Palani S, Srinivasan R, Zambon P, Kamnev A, Gayathri P, Balasubramanian MK. Steric hindrance in the upper 50 kDa domain of the motor Myo2p leads to cytokinesis defects in fission yeast. J Cell Sci 2018; 131:jcs.205625. [PMID: 29162650 PMCID: PMC5818058 DOI: 10.1242/jcs.205625] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 11/06/2017] [Indexed: 02/05/2023] Open
Abstract
Cytokinesis in many eukaryotes requires a contractile actomyosin ring that is placed at the division site. In fission yeast, which is an attractive organism for the study of cytokinesis, actomyosin ring assembly and contraction requires the myosin II heavy chain Myo2p. Although myo2-E1, a temperature-sensitive mutant defective in the upper 50 kDa domain of Myo2p, has been studied extensively, the molecular basis of the cytokinesis defect is not understood. Here, we isolate myo2-E1-Sup2, an intragenic suppressor that contains the original mutation in myo2-E1 (G345R) and a second mutation in the upper 50 kDa domain (Y297C). Unlike myo2-E1-Sup1, a previously characterized myo2-E1 suppressor, myo2-E1-Sup2 reverses actomyosin ring contraction defects in vitro and in vivo Structural analysis of available myosin motor domain conformations suggests that a steric clash in myo2-E1, which is caused by the replacement of a glycine with a bulky arginine, is relieved in myo2-E1-Sup2 by mutation of a tyrosine to a smaller cysteine. Our work provides insight into the function of the upper 50 kDa domain of Myo2p, informs a molecular basis for the cytokinesis defect in myo2-E1, and may be relevant to the understanding of certain cardiomyopathies.
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Affiliation(s)
- Saravanan Palani
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Ramanujam Srinivasan
- School of Biological Sciences, National Institute of Science Engineering and Research (NISER), Bhubaneswar, Odisha 752050, India
| | - Paola Zambon
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Anton Kamnev
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Pananghat Gayathri
- Biology Division, Indian Institute of Science Education and Research (IISER), Pune 411 008, India
| | - Mohan K Balasubramanian
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
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96
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Friend JE, Sayyad WA, Arasada R, McCormick CD, Heuser JE, Pollard TD. Fission yeast Myo2: Molecular organization and diffusion in the cytoplasm. Cytoskeleton (Hoboken) 2017; 75:164-173. [PMID: 29205883 DOI: 10.1002/cm.21425] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 11/22/2017] [Accepted: 11/27/2017] [Indexed: 12/20/2022]
Abstract
Myosin-II is required for the assembly and constriction of cytokinetic contractile rings in fungi and animals. We used electron microscopy, fluorescence recovery after photobleaching (FRAP), and fluorescence correlation spectroscopy (FCS) to characterize the physical properties of Myo2 from fission yeast Schizosaccharomyces pombe. By electron microscopy, Myo2 has two heads and a coiled-coiled tail like myosin-II from other species. The first 65 nm of the tail is a stiff rod, followed by a flexible, less-ordered region up to 30 nm long. Myo2 sediments as a 7 S molecule in high salt, but aggregates rather than forming minifilaments at lower salt concentrations; this is unaffected by heavy chain phosphorylation. We used FRAP and FCS to observe the dynamics of Myo2 in live S. pombe cells and in cell extracts at different salt concentrations; both show that Myo2 with an N-terminal mEGFP tag has a diffusion coefficient of ∼ 3 µm2 s-1 in the cytoplasm of live cells during interphase and mitosis. Photon counting histogram analysis of the FCS data confirmed that Myo2 diffuses as doubled-headed molecules in the cytoplasm. FCS measurements on diluted cell extracts showed that mEGFP-Myo2 has a diffusion coefficient of ∼ 30 µm2 s-1 in 50 to 400 mM KCl concentrations.
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Affiliation(s)
- Janice E Friend
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103
| | - Wasim A Sayyad
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103
| | - Rajesh Arasada
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103
| | - Chad D McCormick
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8103.,Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, Maryland 20892-1855
| | - John E Heuser
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8103
| | - Thomas D Pollard
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8103.,Department of Cell Biology, Yale University, New Haven, Connecticut 06520-8103
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97
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Chang F. Forces that shape fission yeast cells. Mol Biol Cell 2017; 28:1819-1824. [PMID: 28684607 PMCID: PMC5541833 DOI: 10.1091/mbc.e16-09-0671] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 04/18/2017] [Accepted: 04/18/2017] [Indexed: 11/11/2022] Open
Abstract
One of the major challenges of modern cell biology is to understand how cells are assembled from nanoscale components into micrometer-scale entities with a specific size and shape. Here I describe how our quest to understand the morphogenesis of the fission yeast Schizosaccharomyces pombe drove us to investigate cellular mechanics. These studies build on the view that cell shape arises from the physical properties of an elastic cell wall inflated by internal turgor pressure. Consideration of cellular mechanics provides new insights into not only mechanisms responsible for cell-shape determination and growth, but also cellular processes such as cytokinesis and endocytosis. Studies in yeast can help to illuminate approaches and mechanisms to study the mechanobiology of the cell surface in other cell types, including animal cells.
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Affiliation(s)
- Fred Chang
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143
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98
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Hu H, Majneri P, Li D, Kurasawa Y, An T, Dong G, Li Z. Functional analyses of the CIF1-CIF2 complex in trypanosomes identify the structural motifs required for cytokinesis. J Cell Sci 2017; 130:4108-4119. [PMID: 29074577 DOI: 10.1242/jcs.207134] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 10/10/2017] [Indexed: 12/28/2022] Open
Abstract
Cytokinesis in trypanosomes occurs uni-directionally along the longitudinal axis from the cell anterior towards the cell posterior and requires a trypanosome-specific CIF1-CIF2 protein complex. However, little is known about the contribution of the structural motifs in CIF1 and CIF2 to complex assembly and cytokinesis. Here, we demonstrate that the two zinc-finger motifs but not the coiled-coil motif in CIF1 are required for interaction with the EF-hand motifs in CIF2. We further show that localization of CIF1 depends on the coiled-coil motif and the first zinc-finger motif and that localization of CIF2 depends on the EF-hand motifs. Deletion of the coiled-coil motif and mutation of either zinc-finger motif in CIF1 disrupts cytokinesis. Furthermore, mutation of either zinc-finger motif in CIF1 mislocalizes CIF2 to the cytosol and destabilizes CIF2, whereas deletion of the coiled-coil motif in CIF1 spreads CIF2 over to the new flagellum attachment zone and stabilizes CIF2. Together, these results uncover the requirement of the coiled-coil and zinc-finger motifs for CIF1 function in cytokinesis and for CIF2 localization and stability, providing structural insights into the functional interplay between the two cytokinesis regulators.
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Affiliation(s)
- Huiqing Hu
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Paul Majneri
- Max F. Perutz Laboratories, Vienna Bio-center, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Dielan Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Yasuhiro Kurasawa
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Tai An
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Gang Dong
- Max F. Perutz Laboratories, Vienna Bio-center, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Ziyin Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
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99
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Pollard TD. Nine unanswered questions about cytokinesis. J Cell Biol 2017; 216:3007-3016. [PMID: 28807993 PMCID: PMC5626534 DOI: 10.1083/jcb.201612068] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 07/05/2017] [Accepted: 07/20/2017] [Indexed: 12/11/2022] Open
Abstract
Experiments on model systems have revealed that cytokinesis in cells with contractile rings (amoebas, fungi, and animals) depends on shared molecular mechanisms in spite of some differences that emerged during a billion years of divergent evolution. Understanding these fundamental mechanisms depends on identifying the participating proteins and characterizing the mechanisms that position the furrow, assemble the contractile ring, anchor the ring to the plasma membrane, trigger ring constriction, produce force to form a furrow, disassemble the ring, expand the plasma membrane in the furrow, and separate the daughter cell membranes. This review reveals that fascinating questions remain about each step.
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Affiliation(s)
- Thomas D Pollard
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT
- Department of Cell Biology, Yale University, New Haven, CT
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100
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Morita R, Takaine M, Numata O, Nakano K. Molecular dissection of the actin-binding ability of the fission yeast α-actinin, Ain1, in vitro and in vivo. J Biochem 2017; 162:93-102. [PMID: 28338873 DOI: 10.1093/jb/mvx008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 12/27/2016] [Indexed: 02/02/2023] Open
Abstract
A contractile ring (CR) is involved in cytokinesis in animal and yeast cells. Although several types of actin-bundling proteins associate with F-actin in the CR, their individual roles in the CR have not yet been elucidated in detail. Ain1 is the sole α-actinin homologue in the fission yeast Schizosaccharomyces pombe and specifically localizes to the CR with a high turnover rate. S. pombe cells lacking the ain1+ gene show defects in cytokinesis under stress conditions. We herein investigated the biochemical activity and cellular localization mechanisms of Ain1. Ain1 showed weaker affinity to F-actin in vitro than other actin-bundling proteins in S. pombe. We identified a mutation that presumably loosened the interaction between two calponin-homology domains constituting the single actin-binding domain (ABD) of Ain1, which strengthened the actin-binding activity of Ain1. This mutant protein induced a deformation in the ring shape of the CR. Neither a truncated protein consisting only of an N-terminal ABD nor a truncated protein lacking a C-terminal region containing an EF-hand motif localized to the CR, whereas the latter was involved in the bundling of F-actin in vitro. We herein propose detailed mechanisms for how each part of the molecule is involved in the proper cellular localization and function of Ain1.
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Affiliation(s)
- Rikuri Morita
- Department of Biological Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennohdai, Tsukuba, Ibaraki 305-8572, Japan
| | - Masak Takaine
- Department of Biological Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennohdai, Tsukuba, Ibaraki 305-8572, Japan
| | - Osamu Numata
- Department of Biological Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennohdai, Tsukuba, Ibaraki 305-8572, Japan
| | - Kentaro Nakano
- Department of Biological Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennohdai, Tsukuba, Ibaraki 305-8572, Japan
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