1
|
Mangione MC, Chen JS, Gould KL. Cdk1 phosphorylation of fission yeast paxillin inhibits its cytokinetic ring localization. Mol Biol Cell 2021; 32:1534-1544. [PMID: 34133210 PMCID: PMC8351747 DOI: 10.1091/mbc.e20-12-0807] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 06/02/2021] [Accepted: 06/11/2021] [Indexed: 11/11/2022] Open
Abstract
Divisions of the genetic material and cytoplasm are coordinated spatially and temporally to ensure genome integrity. This coordination is mediated in part by the major cell cycle regulator cyclin-dependent kinase (Cdk1). Cdk1 activity peaks during mitosis, but during mitotic exit/cytokinesis Cdk1 activity is reduced, and phosphorylation of its substrates is reversed by various phosphatases including Cdc14, PP1, PP2A, and PP2B. Cdk1 is known to phosphorylate several components of the actin- and myosin-based cytokinetic ring (CR) that mediates division of yeast and animal cells. Here we show that Cdk1 also phosphorylates the Schizosaccharomyces pombe CR component paxillin Pxl1. We determined that both the Cdc14 phosphatase Clp1 and the PP1 phosphatase Dis2 contribute to Pxl1 dephosphorylation at mitotic exit, but PP2B/calcineurin does not. Preventing Pxl1 phosphorylation by Cdk1 results in increased Pxl1 levels, precocious Pxl1 recruitment to the division site, and increased duration of CR constriction. In vitro Cdk1-mediated phosphorylation of Pxl1 inhibits its interaction with the F-BAR domain of the cytokinetic scaffold Cdc15, thereby disrupting a major mechanism of Pxl1 recruitment. Thus, Pxl1 is a novel substrate through which S. pombe Cdk1 and opposing phosphatases coordinate mitosis and cytokinesis.
Collapse
Affiliation(s)
- MariaSanta C. Mangione
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240
| | - Jun-Song Chen
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240
| | - Kathleen L. Gould
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240
| |
Collapse
|
2
|
Morano AA, Dvorin JD. The Ringleaders: Understanding the Apicomplexan Basal Complex Through Comparison to Established Contractile Ring Systems. Front Cell Infect Microbiol 2021; 11:656976. [PMID: 33954122 PMCID: PMC8089483 DOI: 10.3389/fcimb.2021.656976] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 03/19/2021] [Indexed: 12/02/2022] Open
Abstract
The actomyosin contractile ring is a key feature of eukaryotic cytokinesis, conserved across many eukaryotic kingdoms. Recent research into the cell biology of the divergent eukaryotic clade Apicomplexa has revealed a contractile ring structure required for asexual division in the medically relevant genera Toxoplasma and Plasmodium; however, the structure of the contractile ring, known as the basal complex in these parasites, remains poorly characterized and in the absence of a myosin II homolog, it is unclear how the force required of a cytokinetic contractile ring is generated. Here, we review the literature on the basal complex in Apicomplexans, summarizing what is known about its formation and function, and attempt to provide possible answers to this question and suggest new avenues of study by comparing the Apicomplexan basal complex to well-studied, established cytokinetic contractile rings and their mechanisms in organisms such as S. cerevisiae and D. melanogaster. We also compare the basal complex to structures formed during mitochondrial and plastid division and cytokinetic mechanisms of organisms beyond the Opisthokonts, considering Apicomplexan diversity and divergence.
Collapse
Affiliation(s)
- Alexander A Morano
- Biological and Biomedical Sciences, Harvard Medical School, Boston, MA, United States.,Division of Infectious Diseases, Boston Children's Hospital, Boston, MA, United States
| | - Jeffrey D Dvorin
- Division of Infectious Diseases, Boston Children's Hospital, Boston, MA, United States.,Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| |
Collapse
|
3
|
Ueda EI, Kashiwazaki J, Inoué S, Mabuchi I. Fission yeast Adf1 is necessary for reassembly of actin filaments into the contractile ring during cytokinesis. Biochem Biophys Res Commun 2018; 506:330-338. [DOI: 10.1016/j.bbrc.2018.07.156] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 07/31/2018] [Indexed: 01/27/2023]
|
4
|
Lee S. Mathematical Model of Contractile Ring-Driven Cytokinesis in a Three-Dimensional Domain. Bull Math Biol 2018; 80:583-597. [PMID: 29344759 DOI: 10.1007/s11538-018-0390-x] [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: 04/18/2017] [Accepted: 01/05/2018] [Indexed: 12/22/2022]
Abstract
In this paper, a mathematical model of contractile ring-driven cytokinesis is presented by using both phase-field and immersed-boundary methods in a three-dimensional domain. It is one of the powerful hypotheses that cytokinesis happens driven by the contractile ring; however, there are only few mathematical models following the hypothesis, to the author's knowledge. I consider a hybrid method to model the phenomenon. First, a cell membrane is represented by a zero-contour of a phase-field implicitly because of its topological change. Otherwise, immersed-boundary particles represent a contractile ring explicitly based on the author's previous work. Here, the multi-component (or vector-valued) phase-field equation is considered to avoid the emerging of each cell membrane right after their divisions. Using a convex splitting scheme, the governing equation of the phase-field method has unique solvability. The numerical convergence of contractile ring to cell membrane is proved. Several numerical simulations are performed to validate the proposed model.
Collapse
Affiliation(s)
- Seunggyu Lee
- National Institute for Mathematical Sciences, Daejeon, 34047, Republic of Korea.
| |
Collapse
|
5
|
Xiao S, Tong C, Yang Y, Wu M. Mitotic Cortical Waves Predict Future Division Sites by Encoding Positional and Size Information. Dev Cell 2017; 43:493-506.e3. [DOI: 10.1016/j.devcel.2017.10.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 08/02/2017] [Accepted: 10/22/2017] [Indexed: 10/18/2022]
|
6
|
Frappaolo A, Sechi S, Belloni G, Piergentili R, Giansanti MG. Visualization of cleavage furrow proteins in fixed dividing spermatocytes. Methods Cell Biol 2017; 137:85-103. [PMID: 28065322 DOI: 10.1016/bs.mcb.2016.03.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cytokinesis separates the cytoplasmic organelles and the duplicated genome into two daughter cells at the end of cell division. In animal cell cytokinesis, assembly and constriction of the contractile apparatus must be finely coordinated with plasma membrane remodeling and vesicle trafficking at the cleavage furrow. Accurate control of these events during cell cleavage is a fundamental task in all organisms and is also essential for maintaining ploidy and preventing neoplastic transformation. Drosophila male meiosis provides a well-suited cell system for exploring the molecular mechanisms underlying cytokinesis, combining the powerful tools of Drosophila genetics with unique cytological characteristics. Remarkably the large size of male meiotic cells highly facilitates cytological analysis of cytokinesis. Here we describe the main procedures that we use for fixing and visualizing cleavage furrow proteins in male meiotic cells. Moreover, we detail our protocol to detect protein interactions in fixed dividing spermatocytes by applying in situ proximity ligation assay.
Collapse
Affiliation(s)
- A Frappaolo
- Istituto di Biologia e Patologia Molecolari del CNR, Università di Roma Sapienza, Roma, Italy
| | - S Sechi
- Istituto di Biologia e Patologia Molecolari del CNR, Università di Roma Sapienza, Roma, Italy
| | - G Belloni
- Istituto di Biologia e Patologia Molecolari del CNR, Università di Roma Sapienza, Roma, Italy
| | - R Piergentili
- Istituto di Biologia e Patologia Molecolari del CNR, Università di Roma Sapienza, Roma, Italy
| | - M G Giansanti
- Istituto di Biologia e Patologia Molecolari del CNR, Università di Roma Sapienza, Roma, Italy
| |
Collapse
|
7
|
The Cell Killing Mechanisms of Hydroxyurea. Genes (Basel) 2016; 7:genes7110099. [PMID: 27869662 PMCID: PMC5126785 DOI: 10.3390/genes7110099] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 11/03/2016] [Accepted: 11/09/2016] [Indexed: 11/23/2022] Open
Abstract
Hydroxyurea is a well-established inhibitor of ribonucleotide reductase that has a long history of scientific interest and clinical use for the treatment of neoplastic and non-neoplastic diseases. It is currently the staple drug for the management of sickle cell anemia and chronic myeloproliferative disorders. Due to its reversible inhibitory effect on DNA replication in various organisms, hydroxyurea is also commonly used in laboratories for cell cycle synchronization or generating replication stress. However, incubation with high concentrations or prolonged treatment with low doses of hydroxyurea can result in cell death and the DNA damage generated at arrested replication forks is generally believed to be the direct cause. Recent studies in multiple model organisms have shown that oxidative stress and several other mechanisms may contribute to the majority of the cytotoxic effect of hydroxyurea. This review aims to summarize the progress in our understanding of the cell-killing mechanisms of hydroxyurea, which may provide new insights towards the improvement of chemotherapies that employ this agent.
Collapse
|
8
|
Hydroxyurea Induces Cytokinesis Arrest in Cells Expressing a Mutated Sterol-14α-Demethylase in the Ergosterol Biosynthesis Pathway. Genetics 2016; 204:959-973. [PMID: 27585850 DOI: 10.1534/genetics.116.191536] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 08/18/2016] [Indexed: 12/30/2022] Open
Abstract
Hydroxyurea (HU) has been used for the treatment of multiple diseases, such as cancer. The therapeutic effect is generally believed to be due to the suppression of ribonucleotide reductase (RNR), which slows DNA polymerase movement at replication forks and induces an S phase cell cycle arrest in proliferating cells. Although aberrant mitosis and DNA damage generated at collapsed forks are the likely causes of cell death in the mutants with defects in replication stress response, the mechanism underlying the cytotoxicity of HU in wild-type cells remains poorly understood. While screening for new fission yeast mutants that are sensitive to replication stress, we identified a novel mutation in the erg11 gene encoding the enzyme sterol-14α-demethylase in the ergosterol biosynthesis pathway that dramatically sensitizes the cells to chronic HU treatment. Surprisingly, HU mainly arrests the erg11 mutant cells in cytokinesis, not in S phase. Unlike the reversible S phase arrest in wild-type cells, the cytokinesis arrest induced by HU is relatively stable and occurs at low doses of the drug, which likely explains the remarkable sensitivity of the mutant to HU. We also show that the mutation causes sterol deficiency, which may predispose the cells to the cytokinesis arrest and lead to cell death. We hypothesize that in addition to the RNR, HU may have a secondary unknown target(s) inside cells. Identification of such a target(s) may greatly improve the chemotherapies that employ HU or help to expand the clinical usage of this drug for additional pathological conditions.
Collapse
|
9
|
Cheffings T, Burroughs N, Balasubramanian M. Actomyosin Ring Formation and Tension Generation in Eukaryotic Cytokinesis. Curr Biol 2016; 26:R719-R737. [DOI: 10.1016/j.cub.2016.06.071] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
10
|
Measurements of Myosin-II Motor Activity During Cytokinesis in Fission Yeast. Methods Mol Biol 2016; 1369:137-50. [PMID: 26519311 DOI: 10.1007/978-1-4939-3145-3_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Fission yeast myosin-II (Myo2p) represents the critical actin-based motor protein that drives actomyosin ring assembly and constriction during cytokinesis. We detail three different methods to measure Myo2p motor function. Actin-activated ATPases provide a readout of actomyosin ATPase motor activity in a bulk assay; actin filament motility assays reveal the speed and efficiency of myosin-driven actin filament gliding (when motors are anchored); myosin-bead motility assays reveal the speed and efficiency of myosin ensembles traveling along actin filaments (when actin is anchored). Collectively, these methods allow us to combine the standard in vivo approaches common to fission yeast with in vitro biochemical methods to learn more about the mechanistic action of myosin-II during cytokinesis.
Collapse
|
11
|
Li Y, Christensen JR, Homa KE, Hocky GM, Fok A, Sees JA, Voth GA, Kovar DR. The F-actin bundler α-actinin Ain1 is tailored for ring assembly and constriction during cytokinesis in fission yeast. Mol Biol Cell 2016; 27:1821-33. [PMID: 27075176 PMCID: PMC4884072 DOI: 10.1091/mbc.e16-01-0010] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 04/06/2016] [Indexed: 12/18/2022] Open
Abstract
The actomyosin contractile ring is a network of cross-linked actin filaments that facilitates cytokinesis in dividing cells. Contractile ring formation has been well characterized in Schizosaccharomyces pombe, in which the cross-linking protein α-actinin SpAin1 bundles the actin filament network. However, the specific biochemical properties of SpAin1 and whether they are tailored for cytokinesis are not known. Therefore we purified SpAin1 and quantified its ability to dynamically bind and bundle actin filaments in vitro using a combination of bulk sedimentation assays and direct visualization by two-color total internal reflection fluorescence microscopy. We found that, while SpAin1 bundles actin filaments of mixed polarity like other α-actinins, SpAin1 has lower bundling activity and is more dynamic than human α-actinin HsACTN4. To determine whether dynamic bundling is important for cytokinesis in fission yeast, we created the less dynamic bundling mutant SpAin1(R216E). We found that dynamic bundling is critical for cytokinesis, as cells expressing SpAin1(R216E) display disorganized ring material and delays in both ring formation and constriction. Furthermore, computer simulations of initial actin filament elongation and alignment revealed that an intermediate level of cross-linking best facilitates filament alignment. Together our results demonstrate that dynamic bundling by SpAin1 is important for proper contractile ring formation and constriction.
Collapse
Affiliation(s)
- Yujie Li
- Committee on Genetics, Genomics and Systems Biology, University of Chicago, Chicago, IL 60637
| | - Jenna R Christensen
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Kaitlin E Homa
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Glen M Hocky
- Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, and Computation Institute, University of Chicago, Chicago, IL 60637
| | - Alice Fok
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Jennifer A Sees
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Gregory A Voth
- Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, and Computation Institute, University of Chicago, Chicago, IL 60637
| | - David R Kovar
- Committee on Genetics, Genomics and Systems Biology, University of Chicago, Chicago, IL 60637 Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637 Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637
| |
Collapse
|
12
|
Abstract
Fungal cleavage furrow formation during cytokinesis relays in the coordinated contraction of an actomyosin-based ring and the centripetal synthesis of both new plasma membrane and a special wall structure named division septum. Through transmission electron microscopy, the septum exhibits a three-layered structure with a central primary septum, flanked at both sides by the secondary septum. In contrast to the chitinous primary septum present in most of fungi, the fission yeast Schizosaccharomyces pombe does not contain chitin, instead it divides through the formation of a linear β(1,3)glucan-rich primary septum, which has been shown to be specifically stained by the fluorochrome Calcofluor white. Recent findings in S. pombe have revealed the importance of septum synthesis for the steady contraction of the ring during cytokinesis. Therefore, to study the molecular mechanisms that connect the extracellular septum wall with the other components of the cytokinetic machinery located in the plasma membrane and cytoplasm, new experimental approaches are needed. Here we describe the methods developed to image the septum structure by fluorescence microscopy, with a special focus in the analysis of septum progression by the use of time-lapse microscopy.
Collapse
Affiliation(s)
- Juan Carlos Ribas
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, C/ Zacarias Gonzalez 1, 37007, Salamanca, Spain
| | - Juan Carlos G Cortés
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, C/ Zacarias Gonzalez 1, 37007, Salamanca, Spain.
| |
Collapse
|
13
|
Comparative biology of cell division in the fission yeast clade. Curr Opin Microbiol 2015; 28:18-25. [PMID: 26263485 DOI: 10.1016/j.mib.2015.07.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/07/2015] [Accepted: 07/17/2015] [Indexed: 11/21/2022]
Abstract
Cytokinesis must be regulated in time and space in order to preserve genome integrity during cell proliferation and to allow daughter cells to adopt distinct fates and geometries during differentiation. The fission yeast Schizosaccharomyces pombe has been a popular model organism for understanding spatiotemporal regulation of cytokinesis in a symmetrically dividing cell. Recent work on another member of the same genus, Schisozaccharomyces japonicus, suggests that S. pombe may have evolved an unusual division site placement mechanism based on a recently duplicated anillin paralog. Here we discuss an extraordinary evolutionary plasticity of cytokinesis within the fission yeast clade and argue that the comparative cell biology approach may provide functional insights beyond those afforded by scrutinizing individual model species.
Collapse
|
14
|
Jung YW, Mascagni M. Constriction model of actomyosin ring for cytokinesis by fission yeast using a two-state sliding filament mechanism. J Chem Phys 2015; 141:125101. [PMID: 25273478 DOI: 10.1063/1.4896164] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We developed a model describing the structure and contractile mechanism of the actomyosin ring in fission yeast, Schizosaccharomyces pombe. The proposed ring includes actin, myosin, and α-actinin, and is organized into a structure similar to that of muscle sarcomeres. This structure justifies the use of the sliding-filament mechanism developed by Huxley and Hill, but it is probably less organized relative to that of muscle sarcomeres. Ring contraction tension was generated via the same fundamental mechanism used to generate muscle tension, but some physicochemical parameters were adjusted to be consistent with the proposed ring structure. Simulations allowed an estimate of ring constriction tension that reproduced the observed ring constriction velocity using a physiologically possible, self-consistent set of parameters. Proposed molecular-level properties responsible for the thousand-fold slower constriction velocity of the ring relative to that of muscle sarcomeres include fewer myosin molecules involved, a less organized contractile configuration, a low α-actinin concentration, and a high resistance membrane tension. Ring constriction velocity is demonstrated as an exponential function of time despite a near linear appearance. We proposed a hypothesis to explain why excess myosin heads inhibit constriction velocity rather than enhance it. The model revealed how myosin concentration and elastic resistance tension are balanced during cytokinesis in S. pombe.
Collapse
Affiliation(s)
- Yong-Woon Jung
- Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, USA
| | - Michael Mascagni
- Departments of Computer Science, Mathematics and Scientific Computing, and Graduate Program in Molecular Biophysics, Florida State University, Tallahassee, Florida 32306-4530, USA
| |
Collapse
|
15
|
Modeling large-scale dynamic processes in the cell: polarization, waves, and division. Q Rev Biophys 2015; 47:221-48. [PMID: 25124728 DOI: 10.1017/s0033583514000079] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The past decade has witnessed significant developments in molecular biology techniques, fluorescent labeling, and super-resolution microscopy, and together these advances have vastly increased our quantitative understanding of the cell. This detailed knowledge has concomitantly opened the door for biophysical modeling on a cellular scale. There have been comprehensive models produced describing many processes such as motility, transport, gene regulation, and chemotaxis. However, in this review we focus on a specific set of phenomena, namely cell polarization, F-actin waves, and cytokinesis. In each case, we compare and contrast various published models, highlight the relevant aspects of the biology, and provide a sense of the direction in which the field is moving.
Collapse
|
16
|
Zhou Z, Munteanu EL, He J, Ursell T, Bathe M, Huang KC, Chang F. The contractile ring coordinates curvature-dependent septum assembly during fission yeast cytokinesis. Mol Biol Cell 2014; 26:78-90. [PMID: 25355954 PMCID: PMC4279231 DOI: 10.1091/mbc.e14-10-1441] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cytokinesis in fission yeast is accomplished by inward growth of the cell wall septum guided by the contractile ring. The ring promotes local septum growth in a curvature-dependent manner, allowing even a misshapen septum to grow into a more regular shape. This suggests that the ring regulates cell wall assembly through a mechanosensitive mechanism. The functions of the actin-myosin–based contractile ring in cytokinesis remain to be elucidated. Recent findings show that in the fission yeast Schizosaccharomyces pombe, cleavage furrow ingression is driven by polymerization of cell wall fibers outside the plasma membrane, not by the contractile ring. Here we show that one function of the ring is to spatially coordinate septum cell wall assembly. We develop an improved method for live-cell imaging of the division apparatus by orienting the rod-shaped cells vertically using microfabricated wells. We observe that the septum hole and ring are circular and centered in wild-type cells and that in the absence of a functional ring, the septum continues to ingress but in a disorganized and asymmetric manner. By manipulating the cleavage furrow into different shapes, we show that the ring promotes local septum growth in a curvature-dependent manner, allowing even a misshapen septum to grow into a more regular shape. This curvature-dependent growth suggests a model in which contractile forces of the ring shape the septum cell wall by stimulating the cell wall machinery in a mechanosensitive manner. Mechanical regulation of the cell wall assembly may have general relevance to the morphogenesis of walled cells.
Collapse
Affiliation(s)
- Zhou Zhou
- Department of Microbiology and Immunology, Columbia University College of Physicians and Surgeons, New York, NY 10032
| | - Emilia Laura Munteanu
- Department of Microbiology and Immunology, Columbia University College of Physicians and Surgeons, New York, NY 10032
| | - Jun He
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Tristan Ursell
- Department of Bioengineering, Stanford University, Stanford, CA 94305
| | - Mark Bathe
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA 94305 Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305
| | - Fred Chang
- Department of Microbiology and Immunology, Columbia University College of Physicians and Surgeons, New York, NY 10032
| |
Collapse
|
17
|
Chen S, Tang DD. c-Abl tyrosine kinase regulates cytokinesis of human airway smooth muscle cells. Am J Respir Cell Mol Biol 2014; 50:1076-83. [PMID: 24392933 DOI: 10.1165/rcmb.2013-0438oc] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cytokinesis is a critical step of airway smooth muscle cell division that plays an essential role in the development and homeostasis of the respiratory system, as well as the progression of airway remodeling. The mechanisms that regulate smooth muscle cytokinesis are not fully understood. c-Abl (c-Abelson tyrosine kinase) is a nonreceptor protein tyrosine kinase that has a role in regulating actin dynamics and smooth muscle contraction. The role of c-Abl in cytokinesis has not been investigated. Here, c-Abl was found in the contractile ring, as evidenced by immunofluorescent microscopy. In addition, cortactin is a phosphorylatable protein that has been implicated in actin filament assembly. In this report, phosphorylated cortactin was also found in the contractile ring. Knockdown of c-Abl by RNA interference attenuated cortactin phosphorylation in the midzone and contractile ring formation. c-Abl knockdown decreased the number of cells undergoing cytokinesis, but increased the quantity of cells in metaphase/anaphase and the number of multinucleate cells. Treatment with the c-Abl pharmacological inhibitors, imatinib and GNF-5, had similar effects. Furthermore, the expression of a nonphosphorylatable cortactin mutant diminished cytokinesis. Finally, inhibition of actin filament assembly by latrunculin A attenuated c-Abl recruitment to the midzone. Thus, we propose a novel mechanism that regulates smooth muscle cell cytokinesis. c-Abl is recruited to the equator during cytokinesis, which may mediate cortactin phosphorylation. Phosphorylated cortactin may promote actin filament assembly, which facilitates contractile ring formation and cytokinesis. In addition, actin filament polymerization may facilitate the positioning of c-Abl to the contractile ring.
Collapse
Affiliation(s)
- Shu Chen
- Center for Cardiovascular Sciences, Albany Medical College, Albany, New York
| | | |
Collapse
|
18
|
Rincon SA, Bhatia P, Bicho C, Guzman-Vendrell M, Fraisier V, Borek WE, Alves FDL, Dingli F, Loew D, Rappsilber J, Sawin KE, Martin SG, Paoletti A. Pom1 regulates the assembly of Cdr2-Mid1 cortical nodes for robust spatial control of cytokinesis. ACTA ACUST UNITED AC 2014; 206:61-77. [PMID: 24982431 PMCID: PMC4085711 DOI: 10.1083/jcb.201311097] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pom1 regulation of Cdr2 membrane association and interaction with Mid1 prevents Cdr2 assembly into stable nodes in the cell tip region, which ensures proper positioning of cytokinetic ring precursors and accurate division plane positioning in fission yeast. Proper division plane positioning is essential to achieve faithful DNA segregation and to control daughter cell size, positioning, or fate within tissues. In Schizosaccharomyces pombe, division plane positioning is controlled positively by export of the division plane positioning factor Mid1/anillin from the nucleus and negatively by the Pom1/DYRK (dual-specificity tyrosine-regulated kinase) gradients emanating from cell tips. Pom1 restricts to the cell middle cortical cytokinetic ring precursor nodes organized by the SAD-like kinase Cdr2 and Mid1/anillin through an unknown mechanism. In this study, we show that Pom1 modulates Cdr2 association with membranes by phosphorylation of a basic region cooperating with the lipid-binding KA-1 domain. Pom1 also inhibits Cdr2 interaction with Mid1, reducing its clustering ability, possibly by down-regulation of Cdr2 kinase activity. We propose that the dual regulation exerted by Pom1 on Cdr2 prevents Cdr2 assembly into stable nodes in the cell tip region where Pom1 concentration is high, which ensures proper positioning of cytokinetic ring precursors at the cell geometrical center and robust and accurate division plane positioning.
Collapse
Affiliation(s)
- Sergio A Rincon
- Centre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, France Centre National de la Recherche Scientifique, Unite Mixte de Recherche 144, F-75248 Paris, France
| | - Payal Bhatia
- Department of Fundamental Microbiology, University of Lausanne, Lausanne CH-1015, Switzerland
| | - Claudia Bicho
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK
| | - Mercè Guzman-Vendrell
- Centre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, France Centre National de la Recherche Scientifique, Unite Mixte de Recherche 144, F-75248 Paris, France
| | - Vincent Fraisier
- Centre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, France Centre National de la Recherche Scientifique, Unite Mixte de Recherche 144, F-75248 Paris, France
| | - Weronika E Borek
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK
| | - Flavia de Lima Alves
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK
| | - Florent Dingli
- Centre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, FranceCentre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, France
| | - Damarys Loew
- Centre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, FranceCentre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, France
| | - Juri Rappsilber
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK
| | - Kenneth E Sawin
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK
| | - Sophie G Martin
- Department of Fundamental Microbiology, University of Lausanne, Lausanne CH-1015, Switzerland
| | - Anne Paoletti
- Centre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, France Centre National de la Recherche Scientifique, Unite Mixte de Recherche 144, F-75248 Paris, France
| |
Collapse
|
19
|
Muñoz S, Manjón E, Sánchez Y. The putative exchange factor Gef3p interacts with Rho3p GTPase and the septin ring during cytokinesis in fission yeast. J Biol Chem 2014; 289:21995-2007. [PMID: 24947517 DOI: 10.1074/jbc.m114.548792] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The small GTP-binding proteins of the Rho family and its regulatory proteins play a central role in cytokinetic actomyosin ring assembly and cytokinesis. Here we show that the fission yeast guanine nucleotide exchange factor Gef3p interacts with Rho3p at the division site. Gef3p contains a putative DH homology domain and a BAR/IMD-like domain. The protein localized to the division site late in mitosis, where it formed a ring that did not constrict with actomyosin ring (cytokinetic actomyosin ring) invagination; instead, it split into a double ring that resembled the septin ring. Gef3p co-localized with septins and Mid2p and required septins and Mid2p for its localization. Gef3p interacts physically with the GTP-bound form of Rho3p. Although Gef3p is not essential for cell separation, the simultaneous disruption of gef3(+) and Rho3p-interacting proteins, such as Sec8p, an exocyst component, Apm1p, a subunit of the clathrin adaptor complex or For3p, an actin-polymerizing protein, yielded cells with strong defects in septation and polarity respectively. Our results suggest that interactions between septins and Rho-GEFs provide a new targeting mechanism for GTPases in cytokinesis, in this case probably contributing to Rho3p function in vesicle tethering and vesicle trafficking in the later steps of cell separation.
Collapse
Affiliation(s)
- Sofía Muñoz
- From the Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas and Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Zacarías González, s/n. 37007 Salamanca, Spain
| | - Elvira Manjón
- From the Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas and Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Zacarías González, s/n. 37007 Salamanca, Spain
| | - Yolanda Sánchez
- From the Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas and Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Zacarías González, s/n. 37007 Salamanca, Spain
| |
Collapse
|
20
|
Wang L, Tran PT. Visualizing single rod-shaped fission yeast vertically in micro-sized holes on agarose pad made by soft lithography. Methods Cell Biol 2014; 120:227-34. [PMID: 24484668 DOI: 10.1016/b978-0-12-417136-7.00015-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Fission yeast cells are rod-shaped unicellular organism that is normally imaged horizontally with its long axis parallel to image plane. This orientation, while practical, limits the imaging resolution of biological structures which are oriented perpendicular to the long axis of the cell. We present here a method to prepare agarose pads with micro-sized holes to load single fission yeast cell vertically and image cell with its long axis perpendicular to the image plane. As a demonstration, actomyosin ring contraction is shown with this new imaging device.
Collapse
Affiliation(s)
- Li Wang
- Institut Curie, UMR 144 CNRS, Paris, France
| | - Phong T Tran
- Institut Curie, UMR 144 CNRS, Paris, France; Cell & Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| |
Collapse
|
21
|
Muñoz J, Cortés JCG, Sipiczki M, Ramos M, Clemente-Ramos JA, Moreno MB, Martins IM, Pérez P, Ribas JC. Extracellular cell wall β(1,3)glucan is required to couple septation to actomyosin ring contraction. ACTA ACUST UNITED AC 2013; 203:265-82. [PMID: 24165938 PMCID: PMC3812973 DOI: 10.1083/jcb.201304132] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
β(1,3)glucan is critical for contractile ring positioning and for coupling septum synthesis to constriction of the contractile ring and plasma membrane extension during cytokinesis. Cytokinesis has been extensively studied in different models, but the role of the extracellular cell wall is less understood. Here we studied this process in fission yeast. The essential protein Bgs4 synthesizes the main cell wall β(1,3)glucan. We show that Bgs4-derived β(1,3)glucan is required for correct and stable actomyosin ring positioning in the cell middle, before the start of septum formation and anchorage to the cell wall. Consequently, β(1,3)glucan loss generated ring sliding, oblique positioned rings and septa, misdirected septum synthesis indicative of relaxed rings, and uncoupling between a fast ring and membrane ingression and slow septum synthesis, suggesting that cytokinesis can progress with defective septum pushing and/or ring pulling forces. Moreover, Bgs4-derived β(1,3)glucan is essential for secondary septum formation and correct primary septum completion. Therefore, our results show that extracellular β(1,3)glucan is required for cytokinesis to connect the cell wall with the plasma membrane and for contractile ring function, as proposed for the equivalent extracellular matrix in animal cells.
Collapse
Affiliation(s)
- Javier Muñoz
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, 37007 Salamanca, Spain
| | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Tian Y, Luo C, Ouyang Q. A microfluidic synchronizer for fission yeast cells. LAB ON A CHIP 2013; 13:4071-4077. [PMID: 23966136 DOI: 10.1039/c3lc50639h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Among all the cell cycle synchronization technologies, the baby machine may be considered as the most artifact-free method. A baby machine incubates "mother cells" under normal conditions and collects their "babies", producing cell cultures that are similar not only in cell cycle phase but also in age. Unlike many other synchronization methods, no cell-cycle-blocking agent or metabolic stress is introduced in this method. Several macroscale and microfluidic baby machines have been developed for producing synchronized cell colonies. However, for rod-shaped cells like fission yeast (Schizosaccharomyces pombe), it is still a challenge to immobilize only the mother cells in a microfluidic device. Here we presented a new baby machine suitable for fission yeast. The device is fixed one end of the cell and releases the free-end daughter cell every time the cell finishes cytokinesis. A variety of structures for cell immobilization were attempted to find the optimal design. For the convenience of collection and further assay, we integrated into our baby machine chip a cell screener, which exploited the deformation of polymer material to switch between opening and closing states. Synchronous populations of fission yeast cells were produced with this device, its working detail was analyzed and performance was evaluated. The device provides a new on-chip tool for cell biology studies.
Collapse
Affiliation(s)
- Yuan Tian
- Center for Microfluidic and Nanotechnology, The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871 China.
| | | | | |
Collapse
|
23
|
Abstract
Asymmetric cell division (ACD), a mechanism for cell-type diversification in both prokaryotes and eukaryotes, is accomplished through highly coordinated cell-fate segregation, genome partitioning, and cell division. Whereas important paradigms have arisen from the study of animal embryonic divisions, the strategies for choreographing the dynamic subprocesses are, in fact, highly varied. This review examines divergent mechanisms of ACD across different kingdoms. Examples discussed show that there is no obligatory hierarchy among the dynamic events and that asymmetry can emerge from each event, but cell polarization more often occurs as the initial instructive process for patterning ACD especially in the multicellular context.
Collapse
Affiliation(s)
- Rong Li
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA.
| |
Collapse
|
24
|
Jourdain I, Brzezińska EA, Toda T. Fission yeast Nod1 is a component of cortical nodes involved in cell size control and division site placement. PLoS One 2013; 8:e54142. [PMID: 23349808 PMCID: PMC3547912 DOI: 10.1371/journal.pone.0054142] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 12/05/2012] [Indexed: 11/19/2022] Open
Abstract
Most cells enter mitosis once they have reached a defined size. In the fission yeast Schizosaccharomyces pombe, mitotic entry is orchestrated by a geometry-sensing mechanism that involves the Cdk1/Cdc2-inhibiting Wee1 kinase. The factors upstream of Wee1 gather together in interphase to form a characteristic medial and cortical belt of nodes. Nodes are also considered to be precursors of the cytokinesis contractile actomyosin ring (CAR). Here we describe a new component of the interphase nodes and cytokinesis rings, which we named Nod1. Consistent with its role in cell size control at division, nod1Δ cells were elongated and epistatic with regulators of Wee1. Through biochemical and localisation studies, we placed Nod1 in a complex with the Rho-guanine nucleotide exchange factor Gef2. Nod1 and Gef2 mutually recruited each other in nodes and Nod1 also assembles Gef2 in rings. Like gef2Δ, nod1Δ cells showed a mild displacement of their division plane and this phenotype was severely exacerbated when the parallel Polo kinase pathway was also compromised. We conclude that Nod1 specifies the division site by localising Gef2 to the mitotic cell middle. Previous work showed that Gef2 in turn anchors factors that control the spatio-temporal recruitment of the actin nucleation machinery. It is believed that the actin filaments originated from the nodes pull nodes together into a single contractile ring. Surprisingly however, we found that node proteins could form pre-ring helical filaments in a cdc12-112 mutant in which nucleation of the actin ring is impaired. Furthermore, the deletion of either nod1 or gef2 created an un-expected situation where different ring components were recruited sequentially rather than simultaneously. At later stages of cytokinesis, these various rings appeared inter-fitted rather than merged. This study brings a new slant to the understanding of CAR assembly and function.
Collapse
Affiliation(s)
- Isabelle Jourdain
- Cell Regulation Laboratory, London Research Institute, Cancer Research UK, London, United Kingdom
| | - Elspeth A. Brzezińska
- Cell Regulation Laboratory, London Research Institute, Cancer Research UK, London, United Kingdom
| | - Takashi Toda
- Cell Regulation Laboratory, London Research Institute, Cancer Research UK, London, United Kingdom
| |
Collapse
|
25
|
Huber F, Schnauß J, Rönicke S, Rauch P, Müller K, Fütterer C, Käs J. Emergent complexity of the cytoskeleton: from single filaments to tissue. ADVANCES IN PHYSICS 2013; 62:1-112. [PMID: 24748680 PMCID: PMC3985726 DOI: 10.1080/00018732.2013.771509] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2011] [Revised: 01/11/2013] [Indexed: 05/17/2023]
Abstract
Despite their overwhelming complexity, living cells display a high degree of internal mechanical and functional organization which can largely be attributed to the intracellular biopolymer scaffold, the cytoskeleton. Being a very complex system far from thermodynamic equilibrium, the cytoskeleton's ability to organize is at the same time challenging and fascinating. The extensive amounts of frequently interacting cellular building blocks and their inherent multifunctionality permits highly adaptive behavior and obstructs a purely reductionist approach. Nevertheless (and despite the field's relative novelty), the physics approach has already proved to be extremely successful in revealing very fundamental concepts of cytoskeleton organization and behavior. This review aims at introducing the physics of the cytoskeleton ranging from single biopolymer filaments to multicellular organisms. Throughout this wide range of phenomena, the focus is set on the intertwined nature of the different physical scales (levels of complexity) that give rise to numerous emergent properties by means of self-organization or self-assembly.
Collapse
Affiliation(s)
- F. Huber
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
| | - J. Schnauß
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
| | - S. Rönicke
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
| | - P. Rauch
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
| | - K. Müller
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
| | - C. Fütterer
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
| | - J. Käs
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
| |
Collapse
|
26
|
Karagiannis J. Ensuring the faithful execution of cytokinesis in Schizosaccharomyces pombe. Commun Integr Biol 2012; 5:265-71. [PMID: 22896789 PMCID: PMC3419111 DOI: 10.4161/cib.19860] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Eukaryotic cells ensure error-free progress through the cell cycle by monitoring (1) the completion of cell cycle events, (2) damage to critical cellular components, or (3) structural changes such as the attachment of kinetochores to the mitotic spindle. In the presence of damage, or in the face of a reduced capacity to complete essential events, cells are capable of delaying the cell cycle so that damage can be repaired, or previous cell cycle phases can proceed to completion. Although such “checkpoints” have been extensively studied in many organisms—and much is understood with respect to the monitoring of DNA replication and DNA damage—little is known with regards to mechanisms that might monitor the completion of cytokinesis. In this review I summarize recent work from the fission yeast, Schizosaccharomyces pombe, describing the existence of regulatory modules that aid in ensuring the faithful and reliable execution of cytokinesis. Together, these modules promote the maintenance of a “cytokinesis-competent” state characterized by delayed progression into mitosis and the continuous repair and/or re-establishment of the acto-myosin ring. In this way, fission yeast cells are able to increase the likelihood of successful cell division prior to committing to a subsequent cell cycle. The recent demonstration of conservation between S. pombe components of these modules, and human proteins with defined roles in preventing cell division failure, suggest that the lessons learned in S. pombe may be applicable to other eukaryotes.
Collapse
Affiliation(s)
- Jim Karagiannis
- Department of Biology; University of Western Ontario; London, ON Canada
| |
Collapse
|
27
|
Giansanti MG, Fuller MT. What Drosophila spermatocytes tell us about the mechanisms underlying cytokinesis. Cytoskeleton (Hoboken) 2012; 69:869-81. [PMID: 22927345 DOI: 10.1002/cm.21063] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Revised: 08/13/2012] [Accepted: 08/17/2012] [Indexed: 12/21/2022]
Abstract
Cytokinesis separates the genomic material and organelles of a dividing cell equitably into two physically distinct daughter cells at the end of cell division. This highly choreographed process involves coordinated reorganization and regulated action of the actin and microtubule cytoskeletal systems, an assortment of motor proteins, and membrane trafficking components. Due to their large size, the ease with which exquisite cytological analysis may be performed on them, and the availability of numerous mutants and other genetic tools, Drosophila spermatocytes have provided an excellent system for exploring the mechanistic basis for the temporally programmed and precise spatially localized events of cytokinesis. Mutants defective in male meiotic cytokinesis can be easily identified in forward genetic screens by the production of multinucleate spermatids. In addition, the weak spindle assembly checkpoint in spermatocytes, which causes only a small delay of anaphase onset in the presence of unattached chromosomes, allows investigation of whether gene products required for spindle assembly and chromosome segregation are also involved in cytokinesis. Perhaps due to the large size of spermatocytes and the requirement for two rapid-fire rounds of division without intervening S or growth phases during meiosis, male meiotic mutants have also revealed much about molecular mechanisms underlying new membrane addition during cytokinesis. Finally, cell type-specific differences in the events that set up and complete cytokinesis are emerging from comparison of spermatocytes with cells undergoing mitosis either elsewhere in the organism or in tissue culture.
Collapse
Affiliation(s)
- Maria Grazia Giansanti
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie Università Sapienza di Roma, Piazzale A. Moro 5, Roma, Italy.
| | | |
Collapse
|
28
|
Lee IJ, Coffman VC, Wu JQ. Contractile-ring assembly in fission yeast cytokinesis: Recent advances and new perspectives. Cytoskeleton (Hoboken) 2012; 69:751-63. [PMID: 22887981 DOI: 10.1002/cm.21052] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 07/16/2012] [Indexed: 11/07/2022]
Abstract
The fission yeast Schizosaccharomyces pombe is an excellent model organism to study cytokinesis. Here, we review recent advances on contractile-ring assembly in fission yeast. First, we summarize the assembly of cytokinesis nodes, the precursors of a normal contractile ring. IQGAP Rng2 and myosin essential light chain Cdc4 are recruited by the anillin-like protein Mid1, followed by the addition of other cytokinesis node proteins. Mid1 localization on the plasma membrane is stabilized by interphase node proteins. Second, we discuss proteins and processes that contribute to the search, capture, pull, and release mechanism of contractile-ring assembly. Actin filaments nucleated by formin Cdc12, the motor activity of myosin-II, the stiffness of the actin network, and severing of actin filaments by cofilin all play essential roles in contractile-ring assembly. Finally, we discuss the Mid1-independent pathway for ring assembly, and the possible mechanisms underlying the ring maturation and constriction. Collectively, we provide an overview of the current understanding of contractile-ring assembly and uncover future directions in studying cytokinesis in fission yeast.
Collapse
Affiliation(s)
- I-Ju Lee
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, USA
| | | | | |
Collapse
|
29
|
Rincon SA, Paoletti A. Mid1/anillin and the spatial regulation of cytokinesis in fission yeast. Cytoskeleton (Hoboken) 2012; 69:764-77. [DOI: 10.1002/cm.21056] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 07/13/2012] [Accepted: 07/20/2012] [Indexed: 12/20/2022]
|
30
|
Cortés JCG, Sato M, Muñoz J, Moreno MB, Clemente-Ramos JA, Ramos M, Okada H, Osumi M, Durán A, Ribas JC. Fission yeast Ags1 confers the essential septum strength needed for safe gradual cell abscission. ACTA ACUST UNITED AC 2012; 198:637-56. [PMID: 22891259 PMCID: PMC3514033 DOI: 10.1083/jcb.201202015] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The α(1-3)glucan synthase Ags1 is essential for both secondary septum
formation and the primary septum structural strength needed to counter cell
turgor pressure during cell separation. Fungal cytokinesis requires the assembly of a dividing septum wall. In yeast, the
septum has to be selectively digested during the critical cell separation
process. Fission yeast cell wall α(1-3)glucan is essential, but nothing
is known about its localization and function in the cell wall or about
cooperation between the α- and β(1-3)glucan synthases Ags1 and Bgs
for cell wall and septum assembly. Here, we generate a physiological Ags1-GFP
variant and demonstrate a tight colocalization with Bgs1, suggesting a
cooperation in the important early steps of septum construction. Moreover, we
define the essential functions of α(1-3)glucan in septation and cell
separation. We show that α(1-3)glucan is essential for both secondary
septum formation and the primary septum structural strength needed to support
the physical forces of the cell turgor pressure during cell separation.
Consequently, the absence of Ags1 and therefore α(1-3)glucan generates a
special and unique side-explosive cell separation due to an instantaneous
primary septum tearing caused by the turgor pressure.
Collapse
Affiliation(s)
- Juan Carlos G Cortés
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, 37007 Salamanca, Spain
| | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Abstract
Cytokinesis, the final step in cell division, partitions the contents of a single cell into two. In animal cells, cytokinesis occurs through cortical remodeling orchestrated by the anaphase spindle. Cytokinesis relies on a tight interplay between signaling and cellular mechanics and has attracted the attention of both biologists and physicists for more than a century. In this review, we provide an overview of four topics in animal cell cytokinesis: (a) signaling between the anaphase spindle and cortex, (b) the mechanics of cortical remodeling, (c) abscission, and (d) regulation of cytokinesis by the cell cycle machinery. We report on recent progress in these areas and highlight some of the outstanding questions that these findings bring into focus.
Collapse
Affiliation(s)
- Rebecca A Green
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093, USA.
| | | | | |
Collapse
|
32
|
Grewal C, Hickmott J, Rentas S, Karagiannis J. A conserved histone deacetylase with a role in the regulation of cytokinesis in Schizosaccharomyces pombe. Cell Div 2012; 7:13. [PMID: 22559741 PMCID: PMC3485120 DOI: 10.1186/1747-1028-7-13] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 04/20/2012] [Indexed: 11/12/2022] Open
Abstract
Background In Schizosaccharomyces pombe the SET domain protein, Set3p - together with its interacting partners, Snt1p, and Hif2p - form a complex that aids in preventing cell division failure upon mild cytokinetic stress. Intriguingly, the human orthologs of these proteins (MLL5, NCOR2, and TBL1X) are also important for the faithful completion of cytokinesis in tissue culture cells. Since MLL5, NCOR2, and TBL1X form a complex with the histone deacetylase, HDAC3, we sought to determine if an orthologous counterpart played a regulatory role in fission yeast cytokinesis. Results In this report we identify the hos2 gene as the fission yeast HDAC3 ortholog. We show that Hos2p physically interacts with Set3p, Snt1p, and Hif2p, and that hos2∆ mutants are indeed compromised in their ability to reliably complete cell division in the presence of mild cytokinetic stresses. Furthermore, we demonstrate that over-expression of hos2 causes severe morphological and cytokinetic defects. Lastly, through recombinase mediated cassette exchange, we show that expression of human HDAC3 complements the cytokinetic defects exhibited by hos2∆ cells. Conclusions These data support a model in which Hos2p functions as an essential component of the Set3p-Snt1p-Hif2p complex with respect to the regulation of cytokinesis. The ability of human HDAC3 to complement the cytokinesis defects associated with the deletion of the hos2 gene suggests that further analysis of this system could provide insight into the role of HDAC3 in both the regulation of cell division, as well as other biological processes influenced by HDAC3 deacetylation.
Collapse
Affiliation(s)
- Charnpal Grewal
- Department of Biology, University of Western Ontario, London, Ontario N6A-5B7, Canada.
| | | | | | | |
Collapse
|
33
|
Hsp90 interaction with Cdc2 and Plo1 kinases contributes to actomyosin ring condensation in fission yeast. Curr Genet 2012; 58:191-203. [DOI: 10.1007/s00294-012-0376-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 04/02/2012] [Accepted: 04/13/2012] [Indexed: 12/13/2022]
|
34
|
Howard M. How to build a robust intracellular concentration gradient. Trends Cell Biol 2012; 22:311-7. [PMID: 22503534 DOI: 10.1016/j.tcb.2012.03.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 03/16/2012] [Accepted: 03/16/2012] [Indexed: 11/18/2022]
Abstract
Concentration gradients of morphogens are critical regulators of patterning in developmental biology. Increasingly, intracellular concentration gradients have also been found to orchestrate spatial organization, but inside single cells, where they regulate processes such as cell division, polarity and mitotic spindle dynamics. Here, we discuss recent progress in understanding how such intracellular gradients can be built robustly. We focus particularly on the Pom1p gradient in fission yeast, elucidating how various buffering mechanisms operate to ensure precise gradient formation. In this case, a systems-level understanding of the entire mechanism of precise gradient construction is now within reach, with important implications for gradients in both intracellular and developmental contexts.
Collapse
Affiliation(s)
- Martin Howard
- Department of Computational and Systems Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
| |
Collapse
|
35
|
Lee IJ, Wu JQ. Characterization of Mid1 domains for targeting and scaffolding in fission yeast cytokinesis. J Cell Sci 2012; 125:2973-85. [PMID: 22427686 DOI: 10.1242/jcs.102574] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Division-site selection and contractile-ring assembly are two crucial steps in cytokinesis. In fission yeast, the anillin-like Mid1 protein specifies the division site at the cell equator by assembling cortical nodes, the precursors of the contractile ring. Thus, Mid1 is essential for linking the positional cues for the cleavage site to contractile-ring formation. However, how Mid1 domains cooperate to regulate cytokinesis is poorly understood. Here we unravel the functions of different Mid1 domains (motifs) by a series of truncations. We report that the conserved PH domain stabilizes Mid1 in nodes by binding to lipids and is required for Mid1 cortical localization during interphase in the absence of Cdr2 kinase. Mid1 lacking an internal region that is approximately one third of the full-length protein has higher nuclear and cortical concentration and suppresses the division-site positioning defects in cells with a deletion of the dual-specificity tyrosine-regulated kinase Pom1. The N-terminus of Mid1 physically interacts with cytokinesis node proteins. When fused to cortical node protein Cdr2, Mid1(1-100) is sufficient to assemble cytokinesis nodes and the contractile ring. Collectively, our study recognizes domains regulating Mid1 cortical localization and reveals domains sufficient for contractile-ring assembly.
Collapse
Affiliation(s)
- I-Ju Lee
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | | |
Collapse
|
36
|
Phosphorylation of myosin II regulatory light chain controls its accumulation, not that of actin, at the contractile ring in HeLa cells. Exp Cell Res 2012; 318:915-24. [PMID: 22374324 DOI: 10.1016/j.yexcr.2012.02.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 02/02/2012] [Accepted: 02/12/2012] [Indexed: 11/24/2022]
Abstract
During cytokinesis in eukaryotic cells, an actomyosin-based contractile ring (CR) is assembled along the equator of the cell. Myosin II ATPase activity is stimulated by the phosphorylation of the myosin II regulatory light chain (MRLC) in vitro, and phosphorylated MRLC localizes at the CR in various types of cells. Previous studies have determined that phosphorylated MRLC plays an important role in CR furrowing. However, the role of phosphorylated MRLC in CR assembly remains unknown. Here, we have used confocal microscopy to observe dividing HeLa cells expressing fluorescent protein-tagged MRLC mutants and actin during CR assembly near the cortex. Di-phosphomimic MRLC accumulated at the cell equator earlier than non-phosphorylatable MRLC and actin. Interestingly, perturbation of myosin II activity by non-phosphorylatable MRLC expression or treatment with blebbistatin, a myosin II inhibitor, did not alter the time of actin accumulation at the cell equator. Furthermore, inhibition of actin polymerization by treatment with latrunculin A had no effect on MRLC accumulation at the cell equator. Taken together, these data suggest that phosphorylated MRLC temporally controls its own accumulation, but not that of actin, in cultured mammalian cells.
Collapse
|
37
|
Wu P, Zhao R, Ye Y, Wu JQ. Roles of the DYRK kinase Pom2 in cytokinesis, mitochondrial morphology, and sporulation in fission yeast. PLoS One 2011; 6:e28000. [PMID: 22174761 PMCID: PMC3236194 DOI: 10.1371/journal.pone.0028000] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 10/29/2011] [Indexed: 01/04/2023] Open
Abstract
Pom2 is predicted to be a dual-specificity tyrosine-phosphorylation regulated kinase (DYRK) related to Pom1 in Schizosaccharomyces pombe. DYRKs share a kinase domain capable of catalyzing autophosphorylation on tyrosine and exogenous phosphorylation on serine/threonine residues. Here we show that Pom2 is functionally different from the well-characterized Pom1, although they share 55% identity in the kinase domain and the Pom2 kinase domain functionally complements that of Pom1. Pom2 localizes to mitochondria throughout the cell cycle and to the contractile ring during late stages of cytokinesis. Overexpression but not deletion of pom2 results in severe defects in cytokinesis, indicating that Pom2 might share an overlapping function with other proteins in regulating cytokinesis. Gain and loss of function analyses reveal that Pom2 is required for maintaining mitochondrial morphology independently of microtubules. Intriguingly, most meiotic pom2Δ cells form aberrant asci with meiotic and/or forespore membrane formation defects. Taken together, Pom2 is a novel DYRK kinase involved in regulating cytokinesis, mitochondrial morphology, meiosis, and sporulation in fission yeast.
Collapse
Affiliation(s)
- Pengcheng Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America.
| | | | | | | |
Collapse
|
38
|
Chen Q, Pollard TD. Actin filament severing by cofilin is more important for assembly than constriction of the cytokinetic contractile ring. ACTA ACUST UNITED AC 2011; 195:485-98. [PMID: 22024167 PMCID: PMC3206353 DOI: 10.1083/jcb.201103067] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
When fission yeast express mutant cofilin that is inefficient at actin filament severing, cytokinetic contractile ring formation is severely impaired, but ring contraction proceeds efficiently. We created two new mutants of fission yeast cofilin to investigate why cytokinesis in many organisms depends on this small actin-binding protein. These mutant cofilins bound actin monomers normally, but bound and severed ADP-actin filaments much slower than wild-type cofilin. Cells depending on mutant cofilins condensed nodes, precursors of the contractile ring, into clumps rather than rings. Starting from clumped nodes, mutant cells slowly assembled rings from diverse intermediate structures including spiral strands containing actin filaments and other contractile ring proteins. This process in mutant cells depended on α-actinin. These slowly assembled contractile rings constricted at a normal rate but with more variability, indicating ring constriction is not very sensitive to defects in severing by cofilin. Computer simulations of the search-capture-pull and release model of contractile ring formation predicted that nodes clump when the release step is slow, so cofilin severing of actin filament connections between nodes likely contributes to the release step.
Collapse
Affiliation(s)
- Qian Chen
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | | |
Collapse
|
39
|
Ojkic N, Wu JQ, Vavylonis D. Model of myosin node aggregation into a contractile ring: the effect of local alignment. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:374103. [PMID: 21862839 PMCID: PMC3180958 DOI: 10.1088/0953-8984/23/37/374103] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Actomyosin bundles frequently form through aggregation of membrane-bound myosin clusters. One such example is the formation of the contractile ring in fission yeast from a broad band of cortical nodes. Nodes are macromolecular complexes containing several dozens of myosin-II molecules and a few formin dimers. The condensation of a broad band of nodes into the contractile ring has been previously described by a search, capture, pull and release (SCPR) model. In SCPR, a random search process mediated by actin filaments nucleated by formins leads to transient actomyosin connections among nodes that pull one another into a ring. The SCPR model reproduces the transport of nodes over long distances and predicts observed clump-formation instabilities in mutants. However, the model does not generate transient linear elements and meshwork structures as observed in some wild-type and mutant cells during ring assembly. As a minimal model of node alignment, we added short-range aligning forces to the SCPR model representing currently unresolved mechanisms that may involve structural components, cross-linking and bundling proteins. We studied the effect of the local node alignment mechanism on ring formation numerically. We varied the new parameters and found viable rings for a realistic range of values. Morphologically, transient structures that form during ring assembly resemble those observed in experiments with wild-type and cdc25-22 cells. Our work supports a hierarchical process of ring self-organization involving components drawn together from distant parts of the cell followed by progressive stabilization.
Collapse
Affiliation(s)
- Nikola Ojkic
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA
| | | | | |
Collapse
|
40
|
Saberianfar R, Cunningham-Dunlop S, Karagiannis J. Global gene expression analysis of fission yeast mutants impaired in Ser-2 phosphorylation of the RNA pol II carboxy terminal domain. PLoS One 2011; 6:e24694. [PMID: 21931816 PMCID: PMC3171476 DOI: 10.1371/journal.pone.0024694] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 08/15/2011] [Indexed: 12/29/2022] Open
Abstract
In Schizosaccharomyces pombe the nuclear-localized Lsk1p-Lsc1p cyclin dependent kinase complex promotes Ser-2 phosphorylation of the heptad repeats found within the RNA pol II carboxy terminal domain (CTD). Here, we first provide evidence supporting the existence of a third previously uncharacterized Ser-2 CTD kinase subunit, Lsg1p. As expected for a component of the complex, Lsg1p localizes to the nucleus, promotes Ser-2 phosphorylation of the CTD, and physically interacts with both Lsk1p and Lsc1p in vivo. Interestingly, we also demonstrate that lsg1Δ mutants – just like lsk1Δ and lsc1Δ strains – are compromised in their ability to faithfully and reliably complete cytokinesis. Next, to address whether kinase mediated alterations in CTD phosphorylation might selectively alter the expression of genes with roles in cytokinesis and/or the cytoskeleton, global gene expression profiles were analyzed. Mutants impaired in Ser-2 phosphorylation display little change with respect to the level of transcription of most genes. However, genes affecting cytokinesis – including the actin interacting protein gene, aip1 – as well as genes with roles in meiosis, are included in a small subset that are differentially regulated. Significantly, genetic analysis of lsk1Δ aip1Δ double mutants is consistent with Lsk1p and Aip1p acting in a linear pathway with respect to the regulation of cytokinesis.
Collapse
Affiliation(s)
- Reza Saberianfar
- Department of Biology, University of Western Ontario, London, Ontario, Canada
| | | | - Jim Karagiannis
- Department of Biology, University of Western Ontario, London, Ontario, Canada
- * E-mail:
| |
Collapse
|
41
|
Skau CT, Courson DS, Bestul AJ, Winkelman JD, Rock RS, Sirotkin V, Kovar DR. Actin filament bundling by fimbrin is important for endocytosis, cytokinesis, and polarization in fission yeast. J Biol Chem 2011; 286:26964-77. [PMID: 21642440 DOI: 10.1074/jbc.m111.239004] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Through the coordinated action of diverse actin-binding proteins, cells simultaneously assemble actin filaments with distinct architectures and dynamics to drive different processes. Actin filament cross-linking proteins organize filaments into higher order networks, although the requirement of cross-linking activity in cells has largely been assumed rather than directly tested. Fission yeast Schizosaccharomyces pombe assembles actin into three discrete structures: endocytic actin patches, polarizing actin cables, and the cytokinetic contractile ring. The fission yeast filament cross-linker fimbrin Fim1 primarily localizes to Arp2/3 complex-nucleated branched filaments of the actin patch and by a lesser amount to bundles of linear antiparallel filaments in the contractile ring. It is unclear whether Fim1 associates with bundles of parallel filaments in actin cables. We previously discovered that a principal role of Fim1 is to control localization of tropomyosin Cdc8, thereby facilitating cofilin-mediated filament turnover. Therefore, we hypothesized that the bundling ability of Fim1 is dispensable for actin patches but is important for the contractile ring and possibly actin cables. By directly visualizing actin filament assembly using total internal reflection fluorescence microscopy, we determined that Fim1 bundles filaments in both parallel and antiparallel orientations and efficiently bundles Arp2/3 complex-branched filaments in the absence but not the presence of actin capping protein. Examination of cells exclusively expressing a truncated version of Fim1 that can bind but not bundle actin filaments revealed that bundling activity of Fim1 is in fact important for all three actin structures. Therefore, fimbrin Fim1 has diverse roles as both a filament "gatekeeper" and as a filament cross-linker.
Collapse
Affiliation(s)
- Colleen T Skau
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago Illinois 60637, USA
| | | | | | | | | | | | | |
Collapse
|
42
|
Freitag J, Lanver D, Böhmer C, Schink KO, Bölker M, Sandrock B. Septation of infectious hyphae is critical for appressoria formation and virulence in the smut fungus Ustilago maydis. PLoS Pathog 2011; 7:e1002044. [PMID: 21625538 PMCID: PMC3098242 DOI: 10.1371/journal.ppat.1002044] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Accepted: 03/14/2011] [Indexed: 12/24/2022] Open
Abstract
Differentiation of hyphae into specialized infection structures, known as appressoria, is a common feature of plant pathogenic fungi that penetrate the plant cuticle. Appressorium formation in U. maydis is triggered by environmental signals but the molecular mechanism of this hyphal differentiation is largely unknown. Infectious hyphae grow on the leaf surface by inserting regularly spaced retraction septa at the distal end of the tip cell leaving empty sections of collapsed hyphae behind. Here we show that formation of retraction septa is critical for appressorium formation and virulence in U. maydis. We demonstrate that the diaphanous-related formin Drf1 is necessary for actomyosin ring formation during septation of infectious hyphae. Drf1 acts as an effector of a Cdc42 GTPase signaling module, which also consists of the Cdc42-specific guanine nucleotide exchange factor Don1 and the Ste20-like kinase Don3. Deletion of drf1, don1 or don3 abolished formation of retraction septa resulting in reduced virulence. Appressorium formation in these mutants was not completely blocked but infection structures were found only at the tip of short filaments indicating that retraction septa are necessary for appressorium formation in extended infectious hyphae. In addition, appressoria of drf1 mutants penetrated the plant tissue less frequently. Pathogens exhibit various developmental stages during the process of infection and proliferation. The basidiomycete Ustilago maydis is a model organism for plant pathogenic fungi. On the plant surface U. maydis grows as a cell-cycle arrested filament. Growth of infectious hyphae involves regular formation of retraction septa leaving empty sections behind. The tip cell forms an appressorium and penetrates the cuticle. In this study we identified for the first time a signaling module regulating formation of retraction septa in fungal hyphae. The module consists of the highly conserved small GTPase Cdc42, its activator Don1 and the actin-organizing formin Drf1. After penetration of the plant, cell cycle arrest is released and hyphal septation is resumed in planta but was found to be independent of Cdc42 and Drf1. Thus, during infection Cdc42 signaling and Drf1 coordinate hyphal septation events specifically in infectious hyphae in U. maydis. The inability to form retraction septa affects filament elongation and appressorium formation resulting in significantly reduced virulence. We observed a threshold size of the cytoplasm filled tip compartment above which appressorium formation is blocked. These findings highlight that formation of retraction septa, a common feature of filamentous fungi, is an important virulence determinant of U. maydis.
Collapse
Affiliation(s)
- Johannes Freitag
- Department of Biology, Philipps-University Marburg, Marburg, Germany
| | - Daniel Lanver
- Max-Planck-Institute for Terrestrial Microbiology, Department of Organismic Interactions, Marburg, Germany
| | - Christian Böhmer
- Department of Biology, Philipps-University Marburg, Marburg, Germany
| | - Kay Oliver Schink
- Department of Biology, Philipps-University Marburg, Marburg, Germany
- Department of Biochemistry, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway
| | - Michael Bölker
- Department of Biology, Philipps-University Marburg, Marburg, Germany
| | - Björn Sandrock
- Department of Biology, Philipps-University Marburg, Marburg, Germany
- * E-mail:
| |
Collapse
|
43
|
Laporte D, Coffman VC, Lee IJ, Wu JQ. Assembly and architecture of precursor nodes during fission yeast cytokinesis. ACTA ACUST UNITED AC 2011; 192:1005-21. [PMID: 21422229 PMCID: PMC3063137 DOI: 10.1083/jcb.201008171] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mapping of fission yeast precursor node interaction modules and assembly reveals important steps in contractile ring assembly. The contractile ring is essential for cytokinesis in most fungal and animal cells. In fission yeast, cytokinesis nodes are precursors of the contractile ring and mark the future cleavage site. However, their assembly and architecture have not been well described. We found that nodes are assembled stoichiometrically in a hierarchical order with two modules linked by the positional marker anillin Mid1. Mid1 first recruits Cdc4 and IQGAP Rng2 to form module I. Rng2 subsequently recruits the myosin-II subunits Myo2 and Rlc1. Mid1 then independently recruits the F-BAR protein Cdc15 to form module II. Mid1, Rng2, Cdc4, and Cdc15 are stable node components that accumulate close to the plasma membrane. Both modules recruit the formin Cdc12 to nucleate actin filaments. Myo2 heads point into the cell interior, where they efficiently capture actin filaments to condense nodes into the contractile ring. Collectively, our work characterizing the assembly and architecture of precursor nodes defines important steps and molecular players for contractile ring assembly.
Collapse
Affiliation(s)
- Damien Laporte
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | | | | | | |
Collapse
|
44
|
Goyal A, Takaine M, Simanis V, Nakano K. Dividing the spoils of growth and the cell cycle: The fission yeast as a model for the study of cytokinesis. Cytoskeleton (Hoboken) 2011; 68:69-88. [PMID: 21246752 PMCID: PMC3044818 DOI: 10.1002/cm.20500] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 12/15/2010] [Accepted: 12/20/2010] [Indexed: 12/12/2022]
Abstract
Cytokinesis is the final stage of the cell cycle, and ensures completion of both genome segregation and organelle distribution to the daughter cells. Cytokinesis requires the cell to solve a spatial problem (to divide in the correct place, orthogonally to the plane of chromosome segregation) and a temporal problem (to coordinate cytokinesis with mitosis). Defects in the spatiotemporal control of cytokinesis may cause cell death, or increase the risk of tumor formation [Fujiwara et al., 2005 (Fujiwara T, Bandi M, Nitta M, Ivanova EV, Bronson RT, Pellman D. 2005. Cytokinesis failure generating tetraploids promotes tumorigenesis in p53-null cells. Nature 437:1043–1047); reviewed by Ganem et al., 2007 (Ganem NJ, Storchova Z, Pellman D. 2007. Tetraploidy, aneuploidy and cancer. Curr Opin Genet Dev 17:157–162.)]. Asymmetric cytokinesis, which permits the generation of two daughter cells that differ in their shape, size and properties, is important both during development, and for cellular homeostasis in multicellular organisms [reviewed by Li, 2007 (Li R. 2007. Cytokinesis in development and disease: variations on a common theme. Cell Mol Life Sci 64:3044–3058)]. The principal focus of this review will be the mechanisms of cytokinesis in the mitotic cycle of the yeast Schizosaccharomyces pombe. This simple model has contributed significantly to our understanding of how the cell cycle is regulated, and serves as an excellent model for studying aspects of cytokinesis. Here we will discuss the state of our knowledge of how the contractile ring is assembled and disassembled, how it contracts, and what we know of the regulatory mechanisms that control these events and assure their coordination with chromosome segregation.
Collapse
Affiliation(s)
- Anupama Goyal
- EPFL SV ISREC UPSIMSV2.1830, Station 19, CH 1015 Lausanne, Switzerland
| | - Masak Takaine
- Structural Biosciences, Graduate School of Environmental and Life Sciences, University of Tsukuba1-1-1 Tennohdai, Tsukuba, Ibaraki 305-8577, Japan
| | - Viesturs Simanis
- EPFL SV ISREC UPSIMSV2.1830, Station 19, CH 1015 Lausanne, Switzerland
| | - Kentaro Nakano
- Structural Biosciences, Graduate School of Environmental and Life Sciences, University of Tsukuba1-1-1 Tennohdai, Tsukuba, Ibaraki 305-8577, Japan
| |
Collapse
|
45
|
Antagonistic roles of PP2A-Pab1 and Etd1 in the control of cytokinesis in fission yeast. Genetics 2010; 186:1261-70. [PMID: 20876564 DOI: 10.1534/genetics.110.121368] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
In Schizosaccharomyces pombe, Etd1 is a positive regulator of the septation initiation network (SIN), a conserved GTPase-regulated kinase cascade that triggers cytokinesis. Here we show that a mutation in the pab1 gene, which encodes the B-regulatory subunit of the protein phosphatase 2A (PP2A), suppresses mutations in the etd1 gene. Etd1 is required for the function of the GTPase Spg1, a key regulator of SIN signaling. Interestingly, the loss of Pab1 function restored the activity of Spg1 in Etd1-deficient cells. This result suggests that PP2A-Pab1-mediated dephosphorylation inhibits Spg1, thus antagonizing Etd1 function. The loss of pab1 function also rescues the lethality of mutants of other genes in the SIN cascade such as mob1, sid1, and cdc11. Two-hybrid assays indicate that Pab1 physically interacts with Mob1, Sid1, Sid2, and Cdc11, suggesting that the phosphatase 2A B-subunit is a component of the SIN complex. Together, our results indicate that PP2A-Pab1 plays a novel role in cytokinesis, regulating SIN activity at different levels. Pab1 is also required to activate polarized cell growth. Thus, PP2A-Pab1 may be involved in coordinating polar growth and cytokinesis.
Collapse
|
46
|
Almonacid M, Paoletti A. Mechanisms controlling division-plane positioning. Semin Cell Dev Biol 2010; 21:874-80. [PMID: 20708089 DOI: 10.1016/j.semcdb.2010.08.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 06/02/2010] [Accepted: 08/03/2010] [Indexed: 11/27/2022]
Abstract
A critical and irreversible step in the cell division cycle is cytokinesis which physically separates the two daughter cells. This event is consequently subject to tight spatial and temporal regulation. This review focuses on the spatial regulatory mechanisms controlling the position of the division plane. Studies performed in prokaryotic and eukaryotic systems have revealed that various signal-emitting spatial cues - mitotic spindle, nucleus, nucleoid or cell tips - can favour or inhibit the assembly of the cytokinetic apparatus in their vicinity. Most often, several mechanisms operate in parallel to integrate spatial information and promote faithful genome segregation as well as proper cytoplasmic division. We primarily describe the spatial regulatory mechanisms operating in the fission yeast model system, where a detailed molecular understanding of cytokinesis has been achieved. In this system, spatial regulations target a major factor controlling the position of the division plane, the anillin-like protein Mid1. These mechanisms are then compared to spatial regulatory mechanisms prevailing in animal cells and rod-shaped bacteria.
Collapse
Affiliation(s)
- Maria Almonacid
- Institut Curie, Centre de recherche, CNRS, UMR144, Paris, France
| | | |
Collapse
|
47
|
Roncero C, Sánchez Y. Cell separation and the maintenance of cell integrity during cytokinesis in yeast: the assembly of a septum. Yeast 2010; 27:521-30. [DOI: 10.1002/yea.1779] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
|
48
|
Drake T, Vavylonis D. Cytoskeletal dynamics in fission yeast: a review of models for polarization and division. HFSP JOURNAL 2010; 4:122-30. [PMID: 21119765 DOI: 10.2976/1.3385659] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Accepted: 03/18/2010] [Indexed: 11/19/2022]
Abstract
We review modeling studies concerning cytoskeletal activity of fission yeast. Recent models vary in length and time scales, describing a range of phenomena from cellular morphogenesis to polymer assembly. The components of cytoskeleton act in concert to mediate cell-scale events and interactions such as polarization. The mathematical models reduce these events and interactions to their essential ingredients, describing the cytoskeleton by its bulk properties. On a smaller scale, models describe cytoskeletal subcomponents and how bulk properties emerge.
Collapse
Affiliation(s)
- Tyler Drake
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA
| | | |
Collapse
|