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Moyano-Rodríguez Y, Vaquero D, Vilalta-Castany O, Foltman M, Sanchez-Diaz A, Queralt E. PP2A-Cdc55 phosphatase regulates actomyosin ring contraction and septum formation during cytokinesis. Cell Mol Life Sci 2022; 79:165. [PMID: 35230542 PMCID: PMC8888506 DOI: 10.1007/s00018-022-04209-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 02/11/2022] [Accepted: 02/13/2022] [Indexed: 11/03/2022]
Abstract
Eukaryotic cells divide and separate all their components after chromosome segregation by a process called cytokinesis to complete cell division. Cytokinesis is highly regulated by the recruitment of the components to the division site and through post-translational modifications such as phosphorylations. The budding yeast mitotic kinases Cdc28-Clb2, Cdc5, and Dbf2-Mob1 phosphorylate several cytokinetic proteins contributing to the regulation of cytokinesis. The PP2A-Cdc55 phosphatase regulates mitosis counteracting Cdk1- and Cdc5-dependent phosphorylation. This prompted us to propose that PP2A-Cdc55 could also be counteracting the mitotic kinases during cytokinesis. Here we show that in the absence of Cdc55, AMR contraction and the primary septum formation occur asymmetrically to one side of the bud neck supporting a role for PP2A-Cdc55 in cytokinesis regulation. In addition, by in vivo and in vitro assays, we show that PP2A-Cdc55 dephosphorylates the chitin synthase II (Chs2 in budding yeast) a component of the Ingression Progression Complexes (IPCs) involved in cytokinesis. Interestingly, the non-phosphorylable version of Chs2 rescues the asymmetric AMR contraction and the defective septa formation observed in cdc55∆ mutant cells. Therefore, timely dephosphorylation of the Chs2 by PP2A-Cdc55 is crucial for proper actomyosin ring contraction. These findings reveal a new mechanism of cytokinesis regulation by the PP2A-Cdc55 phosphatase and extend our knowledge of the involvement of multiple phosphatases during cytokinesis.
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Affiliation(s)
- Yolanda Moyano-Rodríguez
- Cell Cycle Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Av. Gran Via de L'Hospitalet 199-203, L'Hospitalet de Llobregat, Barcelona, Spain
| | - David Vaquero
- Cell Cycle Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Av. Gran Via de L'Hospitalet 199-203, L'Hospitalet de Llobregat, Barcelona, Spain.,Instituto de Biomedicina de Valencia (IBV-CSIC), C/ Jaume Roig 11, Valencia, Spain
| | - Odena Vilalta-Castany
- Cell Cycle Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Av. Gran Via de L'Hospitalet 199-203, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Magdalena Foltman
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain.,Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Alberto Sanchez-Diaz
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain.,Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Ethel Queralt
- Cell Cycle Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Av. Gran Via de L'Hospitalet 199-203, L'Hospitalet de Llobregat, Barcelona, Spain. .,Instituto de Biomedicina de Valencia (IBV-CSIC), C/ Jaume Roig 11, Valencia, Spain.
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2
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Roncero C, Celador R, Sánchez N, García P, Sánchez Y. The Role of the Cell Integrity Pathway in Septum Assembly in Yeast. J Fungi (Basel) 2021; 7:jof7090729. [PMID: 34575767 PMCID: PMC8471060 DOI: 10.3390/jof7090729] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/30/2021] [Accepted: 08/31/2021] [Indexed: 12/22/2022] Open
Abstract
Cytokinesis divides a mother cell into two daughter cells at the end of each cell cycle and proceeds via the assembly and constriction of a contractile actomyosin ring (CAR). Ring constriction promotes division furrow ingression, after sister chromatids are segregated to opposing sides of the cleavage plane. Cytokinesis contributes to genome integrity because the cells that fail to complete cytokinesis often reduplicate their chromosomes. While in animal cells, the last steps of cytokinesis involve extracellular matrix remodelling and mid-body abscission, in yeast, CAR constriction is coupled to the synthesis of a polysaccharide septum. To preserve cell integrity during cytokinesis, fungal cells remodel their cell wall through signalling pathways that connect receptors to downstream effectors, initiating a cascade of biological signals. One of the best-studied signalling pathways is the cell wall integrity pathway (CWI) of the budding yeast Saccharomyces cerevisiae and its counterpart in the fission yeast Schizosaccharomyces pombe, the cell integrity pathway (CIP). Both are signal transduction pathways relying upon a cascade of MAP kinases. However, despite strong similarities in the assembly of the septa in both yeasts, there are significant mechanistic differences, including the relationship of this process with the cell integrity signalling pathways.
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3
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Yeast as a Model to Understand Actin-Mediated Cellular Functions in Mammals-Illustrated with Four Actin Cytoskeleton Proteins. Cells 2020; 9:cells9030672. [PMID: 32164332 PMCID: PMC7140605 DOI: 10.3390/cells9030672] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/05/2020] [Accepted: 03/05/2020] [Indexed: 12/31/2022] Open
Abstract
The budding yeast Saccharomyces cerevisiae has an actin cytoskeleton that comprises a set of protein components analogous to those found in the actin cytoskeletons of higher eukaryotes. Furthermore, the actin cytoskeletons of S. cerevisiae and of higher eukaryotes have some similar physiological roles. The genetic tractability of budding yeast and the availability of a stable haploid cell type facilitates the application of molecular genetic approaches to assign functions to the various actin cytoskeleton components. This has provided information that is in general complementary to that provided by studies of the equivalent proteins of higher eukaryotes and hence has enabled a more complete view of the role of these proteins. Several human functional homologues of yeast actin effectors are implicated in diseases. A better understanding of the molecular mechanisms underpinning the functions of these proteins is critical to develop improved therapeutic strategies. In this article we chose as examples four evolutionarily conserved proteins that associate with the actin cytoskeleton: (1) yeast Hof1p/mammalian PSTPIP1, (2) yeast Rvs167p/mammalian BIN1, (3) yeast eEF1A/eEF1A1 and eEF1A2 and (4) yeast Yih1p/mammalian IMPACT. We compare the knowledge on the functions of these actin cytoskeleton-associated proteins that has arisen from studies of their homologues in yeast with information that has been obtained from in vivo studies using live animals or in vitro studies using cultured animal cell lines.
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4
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Balabanidou V, Kefi M, Aivaliotis M, Koidou V, Girotti JR, Mijailovsky SJ, Juárez MP, Papadogiorgaki E, Chalepakis G, Kampouraki A, Nikolaou C, Ranson H, Vontas J. Mosquitoes cloak their legs to resist insecticides. Proc Biol Sci 2019; 286:20191091. [PMID: 31311476 PMCID: PMC6661348 DOI: 10.1098/rspb.2019.1091] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Malaria incidence has halved since the year 2000, with 80% of the reduction attributable to the use of insecticides. However, insecticide resistance is now widespread, is rapidly increasing in spectrum and intensity across Africa, and may be contributing to the increase of malaria incidence in 2018. The role of detoxification enzymes and target site mutations has been documented in the major malaria vector Anopheles gambiae; however, the emergence of striking resistant phenotypes suggests the occurrence of additional mechanisms. By comparing legs, the most relevant insect tissue for insecticide uptake, we show that resistant mosquitoes largely remodel their leg cuticles via enhanced deposition of cuticular proteins and chitin, corroborating a leg-thickening phenotype. Moreover, we show that resistant female mosquitoes seal their leg cuticles with higher total and different relative amounts of cuticular hydrocarbons, compared with susceptible ones. The structural and functional alterations in Anopheles female mosquito legs are associated with a reduced uptake of insecticides, substantially contributing to the resistance phenotype.
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Affiliation(s)
- Vasileia Balabanidou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion 70013, Greece
| | - Mary Kefi
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion 70013, Greece.,Department of Biology, University of Crete, Vassilika Vouton, Heraklion 70013, Greece
| | - Michalis Aivaliotis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion 70013, Greece.,Laboratory of Biological Chemistry, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece.,Functional Proteomics and Systems Biology (FunPATh), Center for Interdisciplinary Research and Innovation (CIRI-AUTH), Balkan Center, Thessaloniki, Greece
| | - Venetia Koidou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion 70013, Greece.,Department of Biology, University of Crete, Vassilika Vouton, Heraklion 70013, Greece
| | - Juan R Girotti
- Instituto de Investigaciones Bioquímicas de La Plata, Centro Científico Tecnológico La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas-Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata 1900, Argentina
| | - Sergio J Mijailovsky
- Instituto de Investigaciones Bioquímicas de La Plata, Centro Científico Tecnológico La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas-Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata 1900, Argentina
| | - M Patricia Juárez
- Instituto de Investigaciones Bioquímicas de La Plata, Centro Científico Tecnológico La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas-Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata 1900, Argentina
| | - Eva Papadogiorgaki
- Department of Biology, University of Crete, Vassilika Vouton, Heraklion 70013, Greece
| | - George Chalepakis
- Department of Biology, University of Crete, Vassilika Vouton, Heraklion 70013, Greece
| | - Anastasia Kampouraki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion 70013, Greece.,Pesticide Science Laboratory, Department of Crop Science, Agricultural University of Athens, 11855 Athens, Greece
| | - Christoforos Nikolaou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion 70013, Greece.,Department of Biology, University of Crete, Vassilika Vouton, Heraklion 70013, Greece
| | - Hilary Ranson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - John Vontas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion 70013, Greece.,Pesticide Science Laboratory, Department of Crop Science, Agricultural University of Athens, 11855 Athens, Greece
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5
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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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6
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Verdín J, Sánchez-León E, Rico-Ramírez AM, Martínez-Núñez L, Fajardo-Somera RA, Riquelme M. Off the wall: The rhyme and reason of Neurospora crassa hyphal morphogenesis. ACTA ACUST UNITED AC 2019; 5:100020. [PMID: 32743136 PMCID: PMC7389182 DOI: 10.1016/j.tcsw.2019.100020] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 02/07/2019] [Accepted: 02/10/2019] [Indexed: 12/11/2022]
Abstract
Chitin and β-1,3-glucan synthases are transported separately in chitosomes and macrovesicles. Chitin synthases occupy the core of the SPK; β-1,3-glucan synthases the outer layer. CHS-4 arrival to the SPK and septa is CSE-7 dependent. Rabs YPT-1 and YPT-31 localization at the SPK mimics that of chitosomes and macrovesicles. The exocyst acts as a tether between the SPK outer layer vesicles and the apical PM.
The fungal cell wall building processes are the ultimate determinants of hyphal shape. In Neurospora crassa the main cell wall components, β-1,3-glucan and chitin, are synthesized by enzymes conveyed by specialized vesicles to the hyphal tip. These vesicles follow different secretory routes, which are delicately coordinated by cargo-specific Rab GTPases until their accumulation at the Spitzenkörper. From there, the exocyst mediates the docking of secretory vesicles to the plasma membrane, where they ultimately get fused. Although significant progress has been done on the cellular mechanisms that carry cell wall synthesizing enzymes from the endoplasmic reticulum to hyphal tips, a lot of information is still missing. Here, the current knowledge on N. crassa cell wall composition and biosynthesis is presented with an emphasis on the underlying molecular and cellular secretory processes.
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Key Words
- BGT, β-1,3-glucan transferases
- CHS, chitin synthase
- CLSM, confocal laser scanning microscopy
- CWI, cell wall integrity
- CWP, cell wall proteins
- Cell wall
- ER, endoplasmic reticulum
- FRAP, fluorescence recovery after photobleaching
- GEF, guanine nucleotide exchange factor
- GFP, green fluorescent protein
- GH, glycosyl hydrolases
- GPI, glycosylphosphatidylinositol
- GSC, β-1,3-glucan synthase complex
- MMD, myosin-like motor domain
- MS, mass spectrometry
- MT, microtubule
- NEC, network of elongated cisternae
- PM, plasma membrane
- SPK, Spitzenkörper
- Spitzenkörper
- TIRFM, total internal reflection fluorescence microscopy
- TM, transmembrane
- Tip growth
- Vesicles
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Affiliation(s)
- Jorge Verdín
- Industrial Biotechnology, CIATEJ-Jalisco State Scientific Research and Technology Assistance Center, Mexico National Council for Science and Technology, Zapopan, Jalisco, Mexico
| | - Eddy Sánchez-León
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Adriana M Rico-Ramírez
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada, CICESE Ensenada, Baja California, Mexico
| | - Leonora Martínez-Núñez
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Rosa A Fajardo-Somera
- Karlsruhe Institute of Technology (KIT) South Campus, Institute for Applied Biosciences, Department of Microbiology, Karlsruhe, Germany
| | - Meritxell Riquelme
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada, CICESE Ensenada, Baja California, Mexico
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7
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Brace JL, Doerfler MD, Weiss EL. A cell separation checkpoint that enforces the proper order of late cytokinetic events. J Cell Biol 2019; 218:150-170. [PMID: 30455324 PMCID: PMC6314563 DOI: 10.1083/jcb.201805100] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 08/28/2018] [Accepted: 10/05/2018] [Indexed: 01/28/2023] Open
Abstract
Eukaryotic cell division requires dependency relationships in which late processes commence only after early ones are appropriately completed. We have discovered a system that blocks late events of cytokinesis until early ones are successfully accomplished. In budding yeast, cytokinetic actomyosin ring contraction and membrane ingression are coupled with deposition of an extracellular septum that is selectively degraded in its primary septum immediately after its completion by secreted enzymes. We find this secretion event is linked to septum completion and forestalled when the process is slowed. Delay of septum degradation requires Fir1, an intrinsically disordered protein localized to the cytokinesis site that is degraded upon septum completion but stabilized when septation is aberrant. Fir1 protects cytokinesis in part by inhibiting a separation-specific exocytosis function of the NDR/LATS kinase Cbk1, a key component of "hippo" signaling that induces mother-daughter separation. We term this system enforcement of cytokinesis order, a checkpoint ensuring proper temporal sequence of mechanistically incompatible processes of cytokinesis.
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Affiliation(s)
- Jennifer L Brace
- Department of Molecular Biosciences, Northwestern University, Evanston, IL
| | - Matthew D Doerfler
- Department of Molecular Biosciences, Northwestern University, Evanston, IL
| | - Eric L Weiss
- Department of Molecular Biosciences, Northwestern University, Evanston, IL
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8
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Tamborrini D, Juanes MA, Ibanes S, Rancati G, Piatti S. Recruitment of the mitotic exit network to yeast centrosomes couples septin displacement to actomyosin constriction. Nat Commun 2018; 9:4308. [PMID: 30333493 PMCID: PMC6193047 DOI: 10.1038/s41467-018-06767-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 09/10/2018] [Indexed: 01/11/2023] Open
Abstract
In many eukaryotic organisms cytokinesis is driven by a contractile actomyosin ring (CAR) that guides membrane invagination. What triggers CAR constriction at a precise time of the cell cycle is a fundamental question. In budding yeast CAR is assembled via a septin scaffold at the division site. A Hippo-like kinase cascade, the Mitotic Exit Network (MEN), promotes mitotic exit and cytokinesis, but whether and how these two processes are independently controlled by MEN is poorly understood. Here we show that a critical function of MEN is to promote displacement of the septin ring from the division site, which in turn is essential for CAR constriction. This is independent of MEN control over mitotic exit and involves recruitment of MEN components to the spindle pole body (SPB). Ubiquitination of the SPB scaffold Nud1 inhibits MEN signaling at the end of mitosis and prevents septin ring splitting, thus silencing the cytokinetic machinery. The Mitotic Exit Network (MEN) promotes mitotic exit and cytokinesis but if and how MEN independently controls these two processes is unclear. Here, the authors report that MEN displaces septins from the cell division site to promote actomyosin ring constriction, independently of MEN control of mitotic exit.
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Affiliation(s)
- Davide Tamborrini
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), 1919 Route de Mende, 34293, Montpellier, France.,Max-Planck-Institute of Molecular Physiology, Otto-Hahn Str. 11, 44227, Dortmund, Germany
| | - Maria Angeles Juanes
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), 1919 Route de Mende, 34293, Montpellier, France.,Brandeis University, 415 South Street, Waltham, MA, 02454, USA
| | - Sandy Ibanes
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), 1919 Route de Mende, 34293, Montpellier, France
| | - Giulia Rancati
- Institute of Medical Biology, 8a Biomedical Grove, Singapore, 138648, Singapore
| | - Simonetta Piatti
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), 1919 Route de Mende, 34293, Montpellier, France.
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Abstract
In all animals, oocytes are surrounded by an extracellular matrix upon fertilization. This matrix serves similar purposes in each animal. It functions to mediate sperm binding, to prevent polyspermy, to control the chemical environment of the embryo, and to provide physical protection to the embryo as it developes. The synthesis of the C. elegans matrix, or eggshell, begins when the oocyte enters the spermatheca and is fertilized by a single sperm. The process of eggshell synthesis is thought to take place during the completion of the maternal meiotic divisions such that the multi-layered eggshell is completed by anaphase II. The synthesis of the eggshell occurs in a hierarchical pattern in which the outermost layers are synthesized first in order to capture and retain the innermost layers as they form. Recent studies have revealed that the lipid-rich permeability barrier is distinct from the outer trilaminar eggshell. These new findings alter our previous understanding of the eggshell. This chapter aims to define each of the eggshell layers and the molecules that are known to play significant roles in their formation.
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Affiliation(s)
- Kathryn K Stein
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Andy Golden
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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10
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Foltman M, Filali-Mouncef Y, Crespo D, Sanchez-Diaz A. Cell polarity protein Spa2 coordinates Chs2 incorporation at the division site in budding yeast. PLoS Genet 2018; 14:e1007299. [PMID: 29601579 PMCID: PMC5895073 DOI: 10.1371/journal.pgen.1007299] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 04/11/2018] [Accepted: 03/07/2018] [Indexed: 01/06/2023] Open
Abstract
Deposition of additional plasma membrane and cargoes during cytokinesis in eukaryotic cells must be coordinated with actomyosin ring contraction, plasma membrane ingression and extracellular matrix remodelling. The process by which the secretory pathway promotes specific incorporation of key factors into the cytokinetic machinery is poorly understood. Here, we show that cell polarity protein Spa2 interacts with actomyosin ring components during cytokinesis. Spa2 directly binds to cytokinetic factors Cyk3 and Hof1. The lethal effects of deleting the SPA2 gene in the absence of either Cyk3 or Hof1 can be suppressed by expression of the hypermorphic allele of the essential chitin synthase II (Chs2), a transmembrane protein transported on secretory vesicles that makes the primary septum during cytokinesis. Spa2 also interacts directly with the chitin synthase Chs2. Interestingly, artificial incorporation of Chs2 into the cytokinetic machinery allows the localisation of Spa2 at the site of division. In addition, increased Spa2 protein levels promote Chs2 incorporation at the site of division and primary septum formation. Our data indicate that Spa2 is recruited to the cleavage site to co-operate with the secretory vesicle system and particular actomyosin ring components to promote the incorporation of Chs2 into the so-called 'ingression progression complexes' during cytokinesis in budding yeast.
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Affiliation(s)
- Magdalena Foltman
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Yasmina Filali-Mouncef
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Damaso Crespo
- Departamento de Anatomía y Biología Celular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Alberto Sanchez-Diaz
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
- * E-mail:
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11
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Oh Y, Schreiter JH, Okada H, Wloka C, Okada S, Yan D, Duan X, Bi E. Hof1 and Chs4 Interact via F-BAR Domain and Sel1-like Repeats to Control Extracellular Matrix Deposition during Cytokinesis. Curr Biol 2017; 27:2878-2886.e5. [PMID: 28918945 PMCID: PMC5658023 DOI: 10.1016/j.cub.2017.08.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 07/07/2017] [Accepted: 08/15/2017] [Indexed: 11/24/2022]
Abstract
Localized extracellular matrix (ECM) remodeling is thought to stabilize the cleavage furrow and maintain cell shape during cytokinesis [1-14]. This remodeling is spatiotemporally coordinated with a cytoskeletal structure pertaining to a kingdom of life, for example the FtsZ ring in bacteria [15], the phragmoplast in plants [16], and the actomyosin ring in fungi and animals [17, 18]. Although the cytoskeletal structures have been analyzed extensively, the mechanisms of ECM remodeling remain poorly understood. In the budding yeast Saccharomyces cerevisiae, ECM remodeling refers to sequential formations of the primary and secondary septa that are catalyzed by chitin synthase-II (Chs2) and chitin synthase-III (the catalytic subunit Chs3 and its activator Chs4), respectively [18, 19]. Surprisingly, both Chs2 and Chs3 are delivered to the division site at the onset of cytokinesis [6, 20]. What keeps Chs3 inactive until secondary septum formation remains unknown. Here, we show that Hof1 binds to the Sel1-like repeats (SLRs) of Chs4 via its F-BAR domain and inhibits Chs3-mediated chitin synthesis during cytokinesis. In addition, Hof1 is required for rapid accumulation as well as efficient removal of Chs4 at the division site. This study uncovers a mechanism by which Hof1 controls timely activation of Chs3 during cytokinesis and defines a novel interaction and function for the conserved F-BAR domain and SLR that are otherwise known for their abilities to bind membrane lipids [21, 22] and scaffold protein complex formation [23].
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Affiliation(s)
- Younghoon Oh
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Jennifer H Schreiter
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - 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
| | - Satoshi Okada
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA; Department of Medical Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka 812-8582, Japan
| | - Di Yan
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA; Cleveland Clinic Lerner College of Medicine, Cleveland, OH 44195, USA
| | - Xudong Duan
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, 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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12
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Abstract
Cytokinesis is essential for the survival of all organisms. It requires concerted functions of cell signaling, force production, exocytosis, and extracellular matrix remodeling. Due to the conservation in core components and mechanisms between fungal and animal cells, the budding yeast Saccharomyces cerevisiae has served as an attractive model for studying this fundamental process. In this review, we discuss the mechanics and regulation of distinct events of cytokinesis in budding yeast, including the assembly, constriction, and disassembly of the actomyosin ring, septum formation, abscission, and their spatiotemporal coordination. We also highlight the key concepts and questions that are common to animal and fungal cytokinesis.
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Affiliation(s)
- Yogini P Bhavsar-Jog
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erfei Bi
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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13
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Juanes MA, Piatti S. The final cut: cell polarity meets cytokinesis at the bud neck in S. cerevisiae. Cell Mol Life Sci 2016; 73:3115-36. [PMID: 27085703 PMCID: PMC4951512 DOI: 10.1007/s00018-016-2220-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/22/2016] [Accepted: 04/05/2016] [Indexed: 02/07/2023]
Abstract
Cell division is a fundamental but complex process that gives rise to two daughter cells. It includes an ordered set of events, altogether called "the cell cycle", that culminate with cytokinesis, the final stage of mitosis leading to the physical separation of the two daughter cells. Symmetric cell division equally partitions cellular components between the two daughter cells, which are therefore identical to one another and often share the same fate. In many cases, however, cell division is asymmetrical and generates two daughter cells that differ in specific protein inheritance, cell size, or developmental potential. The budding yeast Saccharomyces cerevisiae has proven to be an excellent system to investigate the molecular mechanisms governing asymmetric cell division and cytokinesis. Budding yeast is highly polarized during the cell cycle and divides asymmetrically, producing two cells with distinct sizes and fates. Many components of the machinery establishing cell polarization during budding are relocalized to the division site (i.e., the bud neck) for cytokinesis. In this review we recapitulate how budding yeast cells undergo polarized processes at the bud neck for cell division.
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Affiliation(s)
- Maria Angeles Juanes
- Centre de Recherche en Biologie Cellulaire de Montpellier, 1919 Route de Mende, 34293, Montpellier, France
- Brandeis University, 415 South Street, Waltham, MA, 02454, USA
| | - Simonetta Piatti
- Centre de Recherche en Biologie Cellulaire de Montpellier, 1919 Route de Mende, 34293, Montpellier, France.
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14
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Chin CF, Tan K, Onishi M, Chew Y, Augustine B, Lee WR, Yeong FM. Timely Endocytosis of Cytokinetic Enzymes Prevents Premature Spindle Breakage during Mitotic Exit. PLoS Genet 2016; 12:e1006195. [PMID: 27447488 PMCID: PMC4957831 DOI: 10.1371/journal.pgen.1006195] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 06/23/2016] [Indexed: 11/30/2022] Open
Abstract
Cytokinesis requires the spatio-temporal coordination of membrane deposition and primary septum (PS) formation at the division site to drive acto-myosin ring (AMR) constriction. It has been demonstrated that AMR constriction invariably occurs only after the mitotic spindle disassembly. It has also been established that Chitin Synthase II (Chs2p) neck localization precedes mitotic spindle disassembly during mitotic exit. As AMR constriction depends upon PS formation, the question arises as to how chitin deposition is regulated so as to prevent premature AMR constriction and mitotic spindle breakage. In this study, we propose that cells regulate the coordination between spindle disassembly and AMR constriction via timely endocytosis of cytokinetic enzymes, Chs2p, Chs3p, and Fks1p. Inhibition of endocytosis leads to over accumulation of cytokinetic enzymes during mitotic exit, which accelerates the constriction of the AMR, and causes spindle breakage that eventually could contribute to monopolar spindle formation in the subsequent round of cell division. Intriguingly, the mitotic spindle breakage observed in endocytosis mutants can be rescued either by deleting or inhibiting the activities of, CHS2, CHS3 and FKS1, which are involved in septum formation. The findings from our study highlight the importance of timely endocytosis of cytokinetic enzymes at the division site in safeguarding mitotic spindle integrity during mitotic exit. The cytokinesis machinery that is required for physical separation of mother-daughter cells during mitosis is highly conserved from yeast to humans. In budding yeast, cytokinesis is achieved via timely delivery of cytokinetic enzymes to the division site that eventually triggers the constriction of AMR. It has been previously demonstrated that cytokinesis invariably occurs after the disassembly of the mitotic spindle. Intriguingly, Chs2p that is responsible for laying down the primary septum has been shown to localize to the division site before mitotic spindle disassembly. In this study, we show that mitotic spindle integrity upon sister chromatid separation is dependent on the continuous endocytosis of cytokinetic enzymes. Failure in the internalization of cytokinetic proteins during mitotic exit causes premature AMR constriction that eventually contributes to the shearing of mitotic spindle. Consequently, cells fail to re-establish a bipolar spindle in the subsequent round of cell division cycle. Our findings provide insights into how the levels of secreted proteins at the division site impacts cytokinesis. We believe this regulation mechanism might be conserved in higher eukaryotic cells as a secreted protein, hemicentin, has been shown recently to be involved in regulating cytokinesis in both Caenorhabditis elegans and mouse embryos.
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Affiliation(s)
- Cheen Fei Chin
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Kaiquan Tan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Masayuki Onishi
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - YuanYuan Chew
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Beryl Augustine
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Wei Ren Lee
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Foong May Yeong
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- * E-mail:
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15
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Rippert D, Heinisch JJ. Investigation of the role of four mitotic septins and chitin synthase 2 for cytokinesis in Kluyveromyces lactis. Fungal Genet Biol 2016; 94:69-78. [PMID: 27422440 DOI: 10.1016/j.fgb.2016.07.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Revised: 07/08/2016] [Accepted: 07/12/2016] [Indexed: 11/15/2022]
Abstract
Septins are key components of the cell division machinery from yeast to humans. The model yeast Saccharomyces cerevisiae has five mitotic septins, Cdc3, Cdc10, Cdc11, Cdc12, and Shs1. Here we characterized the five orthologs from the genetically less-redundant milk yeast Kluyveromyces lactis. We found that except for KlSHS1 all septin genes are essential. Klshs1 deletions displayed temperature-sensitive growth and morphological defects. Heterologous complementation analyses revealed that all five K. lactis genes encode functional orthologs of their S. cerevisiae counterparts. Fluorophore-tagged versions of the K. lactis septins localized to a ring at the incipient bud site and split into two separate rings at the bud neck later in cytokinesis. One of the key proteins recruited to the bud neck by septins in S. cerevisiae is the chitin synthase Chs2, which synthesizes the primary septum. KlCHS2 was found to be essential and deletions showed cytokinetic defects upon spore germination. KlChs2-GFP also localized to the bud neck and to punctate structures in K. lactis. We conclude that cytokinesis in K. lactis is similar to S. cerevisiae and chimeric septin complexes are fully functional in both yeasts. In contrast to some S. cerevisiae strains, KlChs2 and KlCdc10 were found to be essential.
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Affiliation(s)
- Dorthe Rippert
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, 49076 Osnabrück, Germany
| | - Jürgen J Heinisch
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, 49076 Osnabrück, Germany.
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16
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Yang PL, Hsu TH, Wang CW, Chen RH. Lipid droplets maintain lipid homeostasis during anaphase for efficient cell separation in budding yeast. Mol Biol Cell 2016; 27:2368-80. [PMID: 27307588 PMCID: PMC4966979 DOI: 10.1091/mbc.e16-02-0106] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 06/08/2016] [Indexed: 11/11/2022] Open
Abstract
The neutral lipids steryl ester and triacylglycerol (TAG) are stored in the membrane-bound organelle lipid droplet (LD) in essentially all eukaryotic cells. It is unclear what physiological conditions require the mobilization or storage of these lipids. Here, we study the budding yeast mutant are1Δ are2Δ dga1Δ lro1Δ, which cannot synthesize the neutral lipids and therefore lacks LDs. This quadruple mutant is delayed at cell separation upon release from mitotic arrest. The cells have abnormal septa, unstable septin assembly during cytokinesis, and prolonged exocytosis at the division site at the end of cytokinesis. Lipidomic analysis shows a marked increase of diacylglycerol (DAG) and phosphatidic acid, the precursors for TAG, in the mutant during mitotic exit. The cytokinesis and separation defects are rescued by adding phospholipid precursors or inhibiting fatty acid synthesis, which both reduce DAG levels. Our results suggest that converting excess lipids to neutral lipids for storage during mitotic exit is important for proper execution of cytokinesis and efficient cell separation.
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Affiliation(s)
- Po-Lin Yang
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Tzu-Han Hsu
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Chao-Wen Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Rey-Huei Chen
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
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17
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Foltman M, Molist I, Arcones I, Sacristan C, Filali-Mouncef Y, Roncero C, Sanchez-Diaz A. Ingression Progression Complexes Control Extracellular Matrix Remodelling during Cytokinesis in Budding Yeast. PLoS Genet 2016; 12:e1005864. [PMID: 26891268 PMCID: PMC4758748 DOI: 10.1371/journal.pgen.1005864] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 01/22/2016] [Indexed: 12/02/2022] Open
Abstract
Eukaryotic cells must coordinate contraction of the actomyosin ring at the division site together with ingression of the plasma membrane and remodelling of the extracellular matrix (ECM) to support cytokinesis, but the underlying mechanisms are still poorly understood. In eukaryotes, glycosyltransferases that synthesise ECM polysaccharides are emerging as key factors during cytokinesis. The budding yeast chitin synthase Chs2 makes the primary septum, a special layer of the ECM, which is an essential process during cell division. Here we isolated a group of actomyosin ring components that form complexes together with Chs2 at the cleavage site at the end of the cell cycle, which we named ‘ingression progression complexes’ (IPCs). In addition to type II myosin, the IQGAP protein Iqg1 and Chs2, IPCs contain the F-BAR protein Hof1, and the cytokinesis regulators Inn1 and Cyk3. We describe the molecular mechanism by which chitin synthase is activated by direct association of the C2 domain of Inn1, and the transglutaminase-like domain of Cyk3, with the catalytic domain of Chs2. We used an experimental system to find a previously unanticipated role for the C-terminus of Inn1 in preventing the untimely activation of Chs2 at the cleavage site until Cyk3 releases the block on Chs2 activity during late mitosis. These findings support a model for the co-ordinated regulation of cell division in budding yeast, in which IPCs play a central role. Cytokinesis is the process by which a cell divides in two and occurs once cells have replicated and segregated their chromosomes. Eukaryotic cells assemble a molecular machine called the actomyosin ring that drives cytokinesis. Contraction of the actomyosin ring is coupled to ingression of the plasma membrane and extracellular matrix remodelling. In eukaryotes, glycosyltransferases that synthesise polysaccharides of the extracellular matrix are emerging as essential factors during cytokinesis. Defects associated with the function of those glycosyltransferases induce the failure of cell division, which promotes the formation of genetically unstable tetraploid cells. Budding yeast cells contain a glycosyltransferase called Chs2 that makes a special layer of extracellular matrix and is essential during cell division. Our findings provide new insights into the molecular mechanism by which the cytokinesis regulators Inn1 and Cyk3 finely regulate the activity of glycosyltransferase Chs2 at the end of mitosis. In addition we isolated a group of actomyosin ring components that form complexes together with Chs2 and Inn1 at the cleavage site, which we have named ‘ingression progression complexes’. These complexes coordinate the contraction of the actomyosin ring, ingression of the plasma membrane and extracellular matrix remodelling in a precise manner. Chs2 is indeed a key factor for coordinating these events. It appears that similar principles could apply to other eukaryotic species, such as fission yeast even if the identity of the relevant glycosyltransferase has changed over the evolution. Taking into account the conservation of the basic cytokinetic mechanisms future studies should try to determine whether a glycosyltransferase similar to Chs2 plays a key role during cytokinesis in human cells.
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Affiliation(s)
- Magdalena Foltman
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Iago Molist
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Irene Arcones
- Instituto de Biología Funcional y Genómica, Departamento de Microbiología y Genética, CSIC, Universidad de Salamanca, Salamanca, Spain
| | - Carlos Sacristan
- Instituto de Biología Funcional y Genómica, Departamento de Microbiología y Genética, CSIC, Universidad de Salamanca, Salamanca, Spain
| | - Yasmina Filali-Mouncef
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Cesar Roncero
- Instituto de Biología Funcional y Genómica, Departamento de Microbiología y Genética, CSIC, Universidad de Salamanca, Salamanca, Spain
| | - Alberto Sanchez-Diaz
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
- * E-mail:
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18
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Abstract
Cytokinesis is the final process in the cell cycle that physically divides one cell into two. In budding yeast, cytokinesis is driven by a contractile actomyosin ring (AMR) and the simultaneous formation of a primary septum, which serves as template for cell wall deposition. AMR assembly, constriction, primary septum formation and cell wall deposition are successive processes and tightly coupled to cell cycle progression to ensure the correct distribution of genetic material and cell organelles among the two rising cells prior to cell division. The role of the AMR in cytokinesis and the molecular mechanisms that drive AMR constriction and septation are the focus of current research. This review summarizes the recent progresses in our understanding of how budding yeast cells orchestrate the multitude of molecular mechanisms that control AMR driven cytokinesis in a spatio-temporal manner to achieve an error free cell division.
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19
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Fajardo-Somera RA, Jöhnk B, Bayram Ö, Valerius O, Braus GH, Riquelme M. Dissecting the function of the different chitin synthases in vegetative growth and sexual development in Neurospora crassa. Fungal Genet Biol 2015; 75:30-45. [DOI: 10.1016/j.fgb.2015.01.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 12/17/2014] [Accepted: 01/07/2015] [Indexed: 01/22/2023]
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20
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Song J, Yang Q, Yang J, Larsson L, Hao X, Zhu X, Malmgren-Hill S, Cvijovic M, Fernandez-Rodriguez J, Grantham J, Gustafsson CM, Liu B, Nyström T. Essential genetic interactors of SIR2 required for spatial sequestration and asymmetrical inheritance of protein aggregates. PLoS Genet 2014; 10:e1004539. [PMID: 25079602 PMCID: PMC4117435 DOI: 10.1371/journal.pgen.1004539] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 06/16/2014] [Indexed: 11/19/2022] Open
Abstract
Sir2 is a central regulator of yeast aging and its deficiency increases daughter cell inheritance of stress- and aging-induced misfolded proteins deposited in aggregates and inclusion bodies. Here, by quantifying traits predicted to affect aggregate inheritance in a passive manner, we found that a passive diffusion model cannot explain Sir2-dependent failures in mother-biased segregation of either the small aggregates formed by the misfolded Huntingtin, Htt103Q, disease protein or heat-induced Hsp104-associated aggregates. Instead, we found that the genetic interaction network of SIR2 comprises specific essential genes required for mother-biased segregation including those encoding components of the actin cytoskeleton, the actin-associated myosin V motor protein Myo2, and the actin organization protein calmodulin, Cmd1. Co-staining with Hsp104-GFP demonstrated that misfolded Htt103Q is sequestered into small aggregates, akin to stress foci formed upon heat stress, that fail to coalesce into inclusion bodies. Importantly, these Htt103Q foci, as well as the ATPase-defective Hsp104Y662A-associated structures previously shown to be stable stress foci, co-localized with Cmd1 and Myo2-enriched structures and super-resolution 3-D microscopy demonstrated that they are associated with actin cables. Moreover, we found that Hsp42 is required for formation of heat-induced Hsp104Y662A foci but not Htt103Q foci suggesting that the routes employed for foci formation are not identical. In addition to genes involved in actin-dependent processes, SIR2-interactors required for asymmetrical inheritance of Htt103Q and heat-induced aggregates encode essential sec genes involved in ER-to-Golgi trafficking/ER homeostasis.
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Affiliation(s)
- Jia Song
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Qian Yang
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Junsheng Yang
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Lisa Larsson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Xinxin Hao
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Xuefeng Zhu
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Göteborg, Sweden
| | - Sandra Malmgren-Hill
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Marija Cvijovic
- Mathematical Sciences, University of Gothenburg, Gothenburg, Sweden
- Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden
| | | | - Julie Grantham
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Claes M. Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Göteborg, Sweden
| | - Beidong Liu
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
- * E-mail:
| | - Thomas Nyström
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
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21
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Abstract
Productive cell proliferation involves efficient and accurate splitting of the dividing cell into two separate entities. This orderly process reflects coordination of diverse cytological events by regulatory systems that drive the cell from mitosis into G1. In the budding yeast Saccharomyces cerevisiae, separation of mother and daughter cells involves coordinated actomyosin ring contraction and septum synthesis, followed by septum destruction. These events occur in precise and rapid sequence once chromosomes are segregated and are linked with spindle organization and mitotic progress by intricate cell cycle control machinery. Additionally, critical paarts of the mother/daughter separation process are asymmetric, reflecting a form of fate specification that occurs in every cell division. This chapter describes central events of budding yeast cell separation, as well as the control pathways that integrate them and link them with the cell cycle.
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22
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Walker LA, Lenardon MD, Preechasuth K, Munro CA, Gow NAR. Cell wall stress induces alternative fungal cytokinesis and septation strategies. J Cell Sci 2013; 126:2668-77. [PMID: 23606739 DOI: 10.1242/jcs.118885] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In fungi, as with all walled organisms, cytokinesis followed by septation marks the end of the cell cycle and is essential for cell division and viability. For yeasts, the septal cross-wall comprises a ring and primary septal plate composed of chitin, and a secondary septum thickened with β(1,3)-glucan. In the human pathogen Candida albicans, chitin synthase enzyme Chs1 builds the primary septum that is surrounded by a chitin ring made by Chs3. Here we show that the lethal phenotype induced by repression of CHS1 was abrogated by stress-induced synthesis of alternative and novel septal types synthesized by other chitin synthase enzymes that have never before been implicated in septation. Chs2 and Chs8 formed a functional salvage septum, even in the absence of both Chs1 and Chs3. A second type of salvage septum formed by Chs2 in combination with Chs3 or Chs8 was proximally offset in the mother-bud neck. Chs3 alone or in combination with Chs8 formed a greatly thickened third type of salvage septum. Therefore, cell wall stress induced alternative forms of septation that rescued cell division in the absence of Chs1, demonstrating that fungi have previously unsuspected redundant strategies to enable septation and cell division to be maintained, even under potentially lethal environmental conditions.
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Affiliation(s)
- Louise A Walker
- Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
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23
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Jakobsen MK, Cheng Z, Lam SK, Roth-Johnson E, Barfield RM, Schekman R. Phosphorylation of Chs2p regulates interaction with COPII. J Cell Sci 2013; 126:2151-6. [PMID: 23525003 DOI: 10.1242/jcs.115915] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Trafficking of the chitin synthase Chs2p from the endoplasmic reticulum (ER) to the bud-neck in late mitosis is tightly regulated by the cell cycle via phosphorylation of serine residues in the N-terminus of the protein. Here, we describe the effects of Chs2p phosphorylation on the interaction with coat protein complex II (COPII). Identification of a cdc5(ts) mutant, which fails to transport Chs2p-3xGFP to the bud-neck and instead accumulates the protein in intracellular puncta, led us to discover that Chs2p-3xGFP accumulates at ER exit sites in metaphase-arrested wild-type cells. Using an in vitro ER vesicle formation assay we showed that phosphorylation of Chs2p by the cyclin-dependent kinase CDK1 prevents packaging into COPII vesicles, whereas dephosphorylation of Chs2p by the phosphatase Cdc14p stimulates selection into the vesicles. We found that the cytoplasmic N-terminal domain of Chs2p, which contains the CDK1 phosphorylation sites, interacts with the COPII component Sec24p in a yeast two-hybrid assay and that phosphomimetic substitutions of serines at the CDK1 consensus sites reduces the interaction. Our data suggest that dephosphorylation functions as a molecular switch for regulated ER exit of Chs2p.
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Affiliation(s)
- Mia Kyed Jakobsen
- Department of Molecular and Cell Biology and Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA
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24
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Oh Y, Schreiter J, Nishihama R, Wloka C, Bi E. Targeting and functional mechanisms of the cytokinesis-related F-BAR protein Hof1 during the cell cycle. Mol Biol Cell 2013; 24:1305-20. [PMID: 23468521 PMCID: PMC3639043 DOI: 10.1091/mbc.e12-11-0804] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Hof1 targets to the division site by interacting with septins and myosin II sequentially during the cell cycle. It plays a role in cytokinesis by coupling actomyosin ring constriction to primary septum formation through interactions with Myo1 and Chs2. F-BAR proteins are membrane‑associated proteins believed to link the plasma membrane to the actin cytoskeleton in cellular processes such as cytokinesis and endocytosis. In the budding yeast Saccharomyces cerevisiae, the F‑BAR protein Hof1 localizes to the division site in a complex pattern during the cell cycle and plays an important role in cytokinesis. However, the mechanisms underlying its localization and function are poorly understood. Here we show that Hof1 contains three distinct targeting domains that contribute to cytokinesis differentially. The N‑terminal half of Hof1 localizes to the bud neck and the sites of polarized growth during the cell cycle. The neck localization is mediated mainly by an interaction between the second coiled‑coil region in the N‑terminus and the septin Cdc10, whereas the localization to the sites of polarized growth is mediated entirely by the F‑BAR domain. In contrast, the C‑terminal half of Hof1 interacts with Myo1, the sole myosin‑II heavy chain in budding yeast, and localizes to the bud neck in a Myo1‑dependent manner from the onset to the completion of cytokinesis. We also show that the SH3 domain in the C‑terminus plays an important role in maintaining the symmetry of Myo1 ring constriction during cytokinesis and that Hof1 interacts with Chs2, a chitin synthase that is required for primary septum formation. Together these data define a mechanism that accounts for the localization of Hof1 during the cell cycle and suggest that Hof1 may function in cytokinesis by coupling actomyosin ring constriction to primary septum formation through interactions with Myo1 and Chs2.
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Affiliation(s)
- Younghoon Oh
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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25
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The NADPH oxidase complexes in Botrytis cinerea: evidence for a close association with the ER and the tetraspanin Pls1. PLoS One 2013; 8:e55879. [PMID: 23418468 PMCID: PMC3572182 DOI: 10.1371/journal.pone.0055879] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 01/03/2013] [Indexed: 01/27/2023] Open
Abstract
NADPH oxidases (Nox) are major enzymatic systems that generate reactive-oxygen species (ROS) in multicellular eukaryotes. In several fungi they have been shown to be involved in sexual differentiation and pathogenicity. However, in contrast to the well characterized mammalian systems, basic information on the composition, recruitment, and localization of fungal Nox complexes and on the molecular mechanisms of their cellular effects are still lacking. Here we give a detailed analysis of components of the Nox complexes in the gray mold fungus Botrytis cinerea. It had previously been shown that the two catalytic transmembrane subunits BcNoxA and B are important for development of sclerotia and for full virulence, with BcNoxA being involved in spreading of lesions and BcNoxB in penetration; BcNoxR functions as a regulator of both subunits. Here we present evidence (using for the first time a functional GFP fusion able to complement the ΔbcnoxA mutant) that BcNoxA localizes mainly to the ER and at the plasma membrane; BcNoxB shows a similar localization pattern, while the regulator BcNoxR is found in vesicles throughout the hyphae and at the hyphal tip. To identify possible interaction partners, which could be involved in the localization or recruitment of the Nox complexes, we functionally characterized the tetraspanin Pls1, a transmembrane protein, which had been suggested to be a NoxB-interacting partner in the saprophyte Podospora anserina. Knock-out experiments and GFP fusions substantiate a link between BcNoxB and BcPls1 because both deletion mutants have overlapping phenotypes (especially a defect in penetration), and the proteins show a similar localization pattern (ER). However, in contrast to the corresponding protein in P. anserina BcPls1 is important for female fertility, but not for ascospore germination.
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Tudzynski P, Heller J, Siegmund U. Reactive oxygen species generation in fungal development and pathogenesis. Curr Opin Microbiol 2012; 15:653-9. [PMID: 23123514 DOI: 10.1016/j.mib.2012.10.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 10/01/2012] [Accepted: 10/01/2012] [Indexed: 12/20/2022]
Abstract
Reactive oxygen species (ROS) generated by NADPH-dependent oxidases (Nox) have been shown to function as signaling molecules and to be essential for many differentiation processes in mammals and plants. There is growing evidence that ROS are important for many aspects of fungal life including vegetative hyphal growth, differentiation of conidial anastomosis tubes, fruiting body and infection structure formation, and for induction of apoptosis. Recent results from studies in fungal saprophytic and pathogenic model systems have shed new light on the role of Nox in cytoskeleton organization, the structure of Nox complexes and links to components of the apical complex, and the localization of Nox to the endoplasmic reticulum.
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Affiliation(s)
- Paul Tudzynski
- Institut für Biologie und Biotechnologie der Pflanzen, Westf. Wilhelms Universitaet, Schlossplatz 8, D-48143 Muenster, Germany.
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Orlean P. Architecture and biosynthesis of the Saccharomyces cerevisiae cell wall. Genetics 2012; 192:775-818. [PMID: 23135325 PMCID: PMC3522159 DOI: 10.1534/genetics.112.144485] [Citation(s) in RCA: 296] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 08/06/2012] [Indexed: 01/02/2023] Open
Abstract
The wall gives a Saccharomyces cerevisiae cell its osmotic integrity; defines cell shape during budding growth, mating, sporulation, and pseudohypha formation; and presents adhesive glycoproteins to other yeast cells. The wall consists of β1,3- and β1,6-glucans, a small amount of chitin, and many different proteins that may bear N- and O-linked glycans and a glycolipid anchor. These components become cross-linked in various ways to form higher-order complexes. Wall composition and degree of cross-linking vary during growth and development and change in response to cell wall stress. This article reviews wall biogenesis in vegetative cells, covering the structure of wall components and how they are cross-linked; the biosynthesis of N- and O-linked glycans, glycosylphosphatidylinositol membrane anchors, β1,3- and β1,6-linked glucans, and chitin; the reactions that cross-link wall components; and the possible functions of enzymatic and nonenzymatic cell wall proteins.
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Affiliation(s)
- Peter Orlean
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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Devrekanli A, Foltman M, Roncero C, Sanchez-Diaz A, Labib K. Inn1 and Cyk3 regulate chitin synthase during cytokinesis in budding yeasts. J Cell Sci 2012; 125:5453-66. [PMID: 22956544 DOI: 10.1242/jcs.109157] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The chitin synthase that makes the primary septum during cell division in budding yeasts is an important therapeutic target with an unknown activation mechanism. We previously found that the C2-domain of the Saccharomyces cerevisiae Inn1 protein plays an essential but uncharacterised role at the cleavage site during cytokinesis. By combining a novel degron allele of INN1 with a point mutation in the C2-domain, we screened for mutations in other genes that suppress the resulting defect in cell division. In this way, we identified 22 dominant mutations of CHS2 (chitin synthase II) that map to two neighbouring sites in the catalytic domain. Chs2 in isolated cell membranes is normally nearly inactive (unless protease treatment is used to bypass inhibition); however, the dominant suppressor allele Chs2-V377I has enhanced activity in vitro. We show that Inn1 associates with Chs2 in yeast cell extracts. It also interacts in a yeast two-hybrid assay with the N-terminal 65% of Chs2, which contains the catalytic domain. In addition to compensating for mutations in the Inn1 C2-domain, the dominant CHS2 alleles suppress cytokinesis defects produced by the lack of the Cyk3 protein. Our data support a model in which the C2-domain of Inn1 acts in conjunction with Cyk3 to regulate the catalytic domain of Chs2 during cytokinesis. These findings suggest novel approaches for developing future drugs against important fungal pathogens.
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Affiliation(s)
- Asli Devrekanli
- Paterson Institute for Cancer Research, University of Manchester, Wilmslow Road, Manchester, M20 4BX, UK
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29
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Sanchez-Diaz A, Nkosi PJ, Murray S, Labib K. The Mitotic Exit Network and Cdc14 phosphatase initiate cytokinesis by counteracting CDK phosphorylations and blocking polarised growth. EMBO J 2012; 31:3620-34. [PMID: 22872148 DOI: 10.1038/emboj.2012.224] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 07/17/2012] [Indexed: 01/27/2023] Open
Abstract
Polarisation of the actin cytoskeleton must cease during cytokinesis, to support efficient assembly and contraction of the actomyosin ring at the site of cell division, but the underlying mechanisms are still understood poorly in most species. In budding yeast, the Mitotic Exit Network (MEN) releases Cdc14 phosphatase from the nucleolus during anaphase, leading to the inactivation of mitotic forms of cyclin-dependent kinase (CDK) and the onset of septation, before G1-CDK can be reactivated and drive re-polarisation of the actin cytoskeleton to a new bud. Here, we show that premature inactivation of mitotic CDK, before release of Cdc14, allows G1-CDK to divert the actin cytoskeleton away from the actomyosin ring to a new site of polarised growth, thereby delaying progression through cytokinesis. Our data indicate that cells normally avoid this problem via the MEN-dependent release of Cdc14, which counteracts all classes of CDK-mediated phosphorylations during cytokinesis and blocks polarised growth. The dephosphorylation of CDK targets is therefore central to the mechanism by which the MEN and Cdc14 initiate cytokinesis and block polarised growth during late mitosis.
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Affiliation(s)
- Alberto Sanchez-Diaz
- Paterson Institute for Cancer Research, University of Manchester, Manchester, UK
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30
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Wloka C, Bi E. Mechanisms of cytokinesis in budding yeast. Cytoskeleton (Hoboken) 2012; 69:710-26. [DOI: 10.1002/cm.21046] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 06/15/2012] [Indexed: 01/22/2023]
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31
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Bi E, Park HO. Cell polarization and cytokinesis in budding yeast. Genetics 2012; 191:347-87. [PMID: 22701052 PMCID: PMC3374305 DOI: 10.1534/genetics.111.132886] [Citation(s) in RCA: 217] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Accepted: 11/04/2011] [Indexed: 12/26/2022] Open
Abstract
Asymmetric cell division, which includes cell polarization and cytokinesis, is essential for generating cell diversity during development. The budding yeast Saccharomyces cerevisiae reproduces by asymmetric cell division, and has thus served as an attractive model for unraveling the general principles of eukaryotic cell polarization and cytokinesis. Polarity development requires G-protein signaling, cytoskeletal polarization, and exocytosis, whereas cytokinesis requires concerted actions of a contractile actomyosin ring and targeted membrane deposition. In this chapter, we discuss the mechanics and spatial control of polarity development and cytokinesis, emphasizing the key concepts, mechanisms, and emerging questions in the field.
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Affiliation(s)
- Erfei Bi
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6058, USA.
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Oh Y, Chang KJ, Orlean P, Wloka C, Deshaies R, Bi E. Mitotic exit kinase Dbf2 directly phosphorylates chitin synthase Chs2 to regulate cytokinesis in budding yeast. Mol Biol Cell 2012; 23:2445-56. [PMID: 22573892 PMCID: PMC3386209 DOI: 10.1091/mbc.e12-01-0033] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
How cell cycle machinery regulates extracellular matrix (ECM) remodeling during cytokinesis remains poorly understood. In the budding yeast Saccharomyces cerevisiae, the primary septum (PS), a functional equivalent of animal ECM, is synthesized during cytokinesis by the chitin synthase Chs2. Here, we report that Dbf2, a conserved mitotic exit kinase, localizes to the division site after Chs2 and directly phosphorylates Chs2 on several residues, including Ser-217. Both phosphodeficient (chs2-S217A) and phosphomimic (chs2-S217D) mutations cause defects in cytokinesis, suggesting that dynamic phosphorylation-dephosphorylation of Ser-217 is critical for Chs2 function. It is striking that Chs2-S217A constricts asymmetrically with the actomyosin ring (AMR), whereas Chs2-S217D displays little or no constriction and remains highly mobile at the division site. These data suggest that Chs2 phosphorylation by Dbf2 triggers its dissociation from the AMR during the late stage of cytokinesis. Of interest, both chs2-S217A and chs2-S217D mutants are robustly suppressed by increased dosage of Cyk3, a cytokinesis protein that displays Dbf2-dependent localization and also stimulates Chs2-mediated chitin synthesis. Thus Dbf2 regulates PS formation through at least two independent pathways: direct phosphorylation and Cyk3-mediated activation of Chs2. Our study establishes a mechanism for direct cell cycle control of ECM remodeling during cytokinesis.
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Affiliation(s)
- Younghoon Oh
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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33
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Tekletsadik YK, Sonn R, Osman MA. A conserved role of IQGAP1 in regulating TOR complex 1. J Cell Sci 2012; 125:2041-52. [PMID: 22328503 DOI: 10.1242/jcs.098947] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Defining the mechanisms that control cell growth and division is crucial to understanding cell homeostasis, which impacts human diseases such as cancer and diabetes. IQGAP1, a widely conserved effector and/or regulator of the GTPase CDC42, is a putative oncoprotein that controls cell proliferation; however, its mechanism in tumorigenesis is unknown. The mechanistic target of rapamycin (mTOR) pathway, the center of cell growth control, is commonly activated in human cancers, but has proved to be an ineffective clinical target because of an incomplete understanding of its mechanisms in cell growth inhibition. Using complementary studies in yeast and mammalian cells, we examined a potential role for IQGAP1 in regulating the negative feedback loop (NFL) of mTOR complex 1 (mTORC1) that controls cell growth. Two-hybrid screens identified the yeast TORC1-specific subunit Tco89p as an Iqg1p-binding partner, sharing roles in rapamycin-sensitive growth, axial-bud-site selection and cytokinesis, thus coupling cell growth and division. Mammalian IQGAP1 binds mTORC1 and Akt1 and in response to epidermal growth factor (EGF), cells expressing the mTORC1-Akt1-binding region (IQGAP1(IR-WW)) contained attenuated phosphorylated ERK1/2 (ERK1/2-P) activity and inactive glycogen synthase kinase 3α/β (GSK3α/β), which control apoptosis. Interestingly, these cells displayed a high level of Akt1 S473-P, but an attenuated level of the mTORC1-dependent kinase S6K1 T389-P and induced mTORC1-Akt1- and EGF-dependent transformed phenotypes. Moreover, IQGAP1 appears to influence cell abscission and its activity is elevated in carcinoma cell lines. These findings support the hypothesis that IQGAP1 acts upstream on the mTORC1-S6K1→Akt1 NFL and downstream of it, to couple cell growth and division, and thus like a rheostat, regulates cell homeostasis, dysregulation of which leads to tumorigenesis or other diseases. These results could have implications for the development of the next generation of anticancer therapeutics.
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Affiliation(s)
- Yemsrach K Tekletsadik
- Institute for Biotechnology and Life Sciences, Cornell University, Ithaca, NY 14853-2703, USA
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34
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Rogg LE, Fortwendel JR, Juvvadi PR, Steinbach WJ. Regulation of expression, activity and localization of fungal chitin synthases. Med Mycol 2012; 50:2-17. [PMID: 21526913 PMCID: PMC3660733 DOI: 10.3109/13693786.2011.577104] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The fungal cell wall represents an attractive target for pharmacologic inhibition, as many of the components are fungal-specific. Though targeted inhibition of β-glucan synthesis is effective treatment for certain fungal infections, the ability of the cell wall to dynamically compensate via the cell wall integrity pathway may limit overall efficacy. To date, chitin synthesis inhibitors have not been successfully deployed in the clinical setting. Fungal chitin synthesis is a complex and highly regulated process. Regulation of chitin synthesis occurs on multiple levels, thus targeting of these regulatory pathways may represent an exciting alternative approach. A variety of signaling pathways have been implicated in chitin synthase regulation, at both transcriptional and post-transcriptional levels. Recent research suggests that localization of chitin synthases likely represents a major regulatory mechanism. However, much of the regulatory machinery is not necessarily shared among different chitin synthases. Thus, an in-depth understanding of the precise roles of each protein in cell wall maintenance and repair will be essential to identifying the most likely therapeutic targets.
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Affiliation(s)
- Luise E. Rogg
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham NC, USA
| | - Jarrod R. Fortwendel
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham NC, USA
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham NC, USA
| | - Praveen R. Juvvadi
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham NC, USA
| | - William J. Steinbach
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham NC, USA
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham NC, USA
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Abstract
Studies of the processes leading to the construction of a bud and its separation from the mother cell in Saccharomyces cerevisiae have provided foundational paradigms for the mechanisms of polarity establishment, cytoskeletal organization, and cytokinesis. Here we review our current understanding of how these morphogenetic events occur and how they are controlled by the cell-cycle-regulatory cyclin-CDK system. In addition, defects in morphogenesis provide signals that feed back on the cyclin-CDK system, and we review what is known regarding regulation of cell-cycle progression in response to such defects, primarily acting through the kinase Swe1p. The bidirectional communication between morphogenesis and the cell cycle is crucial for successful proliferation, and its study has illuminated many elegant and often unexpected regulatory mechanisms. Despite considerable progress, however, many of the most puzzling mysteries in this field remain to be resolved.
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Affiliation(s)
- Audrey S. Howell
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710
| | - Daniel J. Lew
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710
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36
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Chin CF, Bennett AM, Ma WK, Hall MC, Yeong FM. Dependence of Chs2 ER export on dephosphorylation by cytoplasmic Cdc14 ensures that septum formation follows mitosis. Mol Biol Cell 2011; 23:45-58. [PMID: 22072794 PMCID: PMC3248903 DOI: 10.1091/mbc.e11-05-0434] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Sequestration of Cdc14 from the cytoplasm ensures Chs2 ER retention after MEN activation. The interdependence of chromosome segregation, MEN activation, decrease in mitotic CDK activity, and Cdc14 dispersal provides an effective mechanism for cells to order late mitotic events. Cytokinesis, which leads to the physical separation of two dividing cells, is normally restrained until after nuclear division. In Saccharomyces cerevisiae, chitin synthase 2 (Chs2), which lays down the primary septum at the mother–daughter neck, also ensures proper actomyosin ring constriction during cytokinesis. During the metaphase-to-anaphase transition, phosphorylation of Chs2 by the mitotic cyclin-dependent kinase (Cdk1) retains Chs2 at the endoplasmic reticulum (ER), thereby preventing its translocation to the neck. Upon Cdk1 inactivation at the end of mitosis, Chs2 is exported from the ER and targeted to the neck. The mechanism for triggering Chs2 ER export thus far is unknown. We show here that Chs2 ER export requires the direct reversal of the inhibitory Cdk1 phosphorylation sites by Cdc14 phosphatase, the ultimate effector of the mitotic exit network (MEN). We further show that only Cdc14 liberated by the MEN after completion of chromosome segregation, and not Cdc14 released in early anaphase by the Cdc fourteen early anaphase release pathway, triggers Chs2 ER exit. Presumably, the reduced Cdk1 activity in late mitosis further favors dephosphorylation of Chs2 by Cdc14. Thus, by requiring declining Cdk1 activity and Cdc14 nuclear release for Chs2 ER export, cells ensure that septum formation is contingent upon chromosome separation and exit from mitosis.
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Affiliation(s)
- Cheen Fei Chin
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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37
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Wloka C, Nishihama R, Onishi M, Oh Y, Hanna J, Pringle JR, Krauss M, Bi E. Evidence that a septin diffusion barrier is dispensable for cytokinesis in budding yeast. Biol Chem 2011; 392:813-29. [PMID: 21824009 DOI: 10.1515/bc.2011.083] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Septins are essential for cytokinesis in Saccharomyces cerevisiae, but their precise roles remain elusive. Currently, it is thought that before cytokinesis, the hourglass-shaped septin structure at the mother-bud neck acts as a scaffold for assembly of the actomyosin ring (AMR) and other cytokinesis factors. At the onset of cytokinesis, the septin hourglass splits to form a double ring that sandwiches the AMR and may function as diffusion barriers to restrict diffusible cytokinesis factors to the division site. Here, we show that in cells lacking the septin Cdc10 or the septin-associated protein Bud4, the septins form a ring-like structure at the mother-bud neck that fails to re-arrange into a double ring early in cytokinesis. Strikingly, AMR assembly and constriction, the localization of membrane-trafficking and extracellular-matrix-remodeling factors, cytokinesis, and cell-wall-septum formation all occur efficiently in cdc10Δ and bud4Δ mutants. Thus, diffusion barriers formed by the septin double ring do not appear to be critical for S. cerevisiae cytokinesis. However, an AMR mutation and a septin mutation have synergistic effects on cytokinesis and the localization of cytokinesis proteins, suggesting that tethering to the AMR and a septin diffusion barrier may function redundantly to localize proteins to the division site.
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Affiliation(s)
- Carsten Wloka
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6058, USA
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38
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Meitinger F, Petrova B, Lombardi IM, Bertazzi DT, Hub B, Zentgraf H, Pereira G. Targeted localization of Inn1, Cyk3 and Chs2 by the mitotic-exit network regulates cytokinesis in budding yeast. J Cell Sci 2010; 123:1851-61. [PMID: 20442249 DOI: 10.1242/jcs.063891] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The mitotic-exit network (MEN) is a signaling pathway that is essential for the coordination of mitotic exit and cytokinesis. Whereas the role of the MEN in mitotic exit is well established, the molecular mechanisms by which MEN components regulate cytokinesis remain poorly understood. Here, we show that the MEN controls components involved in septum formation, including Inn1, Cyk3 and Chs2. MEN-deficient mutants, forced to exit mitosis as a result of Cdk1 inactivation, show defects in targeting Cyk3 and Inn1 to the bud-neck region. In addition, we found that the chitin synthase Chs2 did not efficiently localize at the bud neck in the absence of MEN activity. Ultrastructural analysis of the bud neck revealed that low MEN activity led to unilateral, uncoordinated extension of the primary and secondary septa. This defect was partially suppressed by increased levels of Cyk3. We therefore propose that the MEN directly controls cytokinesis via targeting of Inn1, Cyk3 and Chs2 to the bud neck.
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Affiliation(s)
- Franz Meitinger
- German Cancer Research Centre, DKFZ-ZMBH Alliance, Molecular Biology of Centrosomes and Cilia Unit, Im Neuenheimer Feld 581, 69120 Heidelberg, Germany
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Nishihama R, Schreiter JH, Onishi M, Vallen EA, Hanna J, Moravcevic K, Lippincott MF, Han H, Lemmon MA, Pringle JR, Bi E. Role of Inn1 and its interactions with Hof1 and Cyk3 in promoting cleavage furrow and septum formation in S. cerevisiae. ACTA ACUST UNITED AC 2009; 185:995-1012. [PMID: 19528296 PMCID: PMC2711614 DOI: 10.1083/jcb.200903125] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cytokinesis requires coordination of actomyosin ring (AMR) contraction with rearrangements of the plasma membrane and extracellular matrix. In Saccharomyces cerevisiae, new membrane, the chitin synthase Chs2 (which forms the primary septum [PS]), and the protein Inn1 are all delivered to the division site upon mitotic exit even when the AMR is absent. Inn1 is essential for PS formation but not for Chs2 localization. The Inn1 C-terminal region is necessary for localization, and distinct PXXP motifs in this region mediate functionally important interactions with SH3 domains in the cytokinesis proteins Hof1 (an F-BAR protein) and Cyk3 (whose overexpression can restore PS formation in inn1Δ cells). The Inn1 N terminus resembles C2 domains but does not appear to bind phospholipids; nonetheless, when overexpressed or fused to Hof1, it can provide Inn1 function even in the absence of the AMR. Thus, Inn1 and Cyk3 appear to cooperate in activating Chs2 for PS formation, which allows coordination of AMR contraction with ingression of the cleavage furrow.
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Affiliation(s)
- Ryuichi Nishihama
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
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40
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Park SY, Cable AE, Blair J, Stockstill KE, Shannnon KB. Bub2 regulation of cytokinesis and septation in budding yeast. BMC Cell Biol 2009; 10:43. [PMID: 19490645 PMCID: PMC2701927 DOI: 10.1186/1471-2121-10-43] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Accepted: 06/02/2009] [Indexed: 11/17/2022] Open
Abstract
Background The mitotic exit network (MEN) is required for events at the end of mitosis such as degradation of mitotic cyclins and cytokinesis. Bub2 and its binding partner Bfa1 act as a GTPase activating protein (GAP) to negatively regulate the MEN GTPase Tem1. The Bub2/Bfa1 checkpoint pathway is required to delay the cell cycle in response to mispositioned spindles. In addition to its role in mitotic exit, Tem1 is required for actomyosin ring contraction. Results To test the hypothesis that the Bub2 pathway prevents premature actin ring assembly, we compared the timing of actin ring formation in wild type, bub2Δ, mad2Δ, and bub2Δmad2Δ cells both with and without microtubules. There was no difference in the timing of actin ring formation between wild type and mutant cells in a synchronized cell cycle. In the presence of nocodazole, both bub2Δ and mad2Δ cells formed rings after a delay of the same duration. Double mutant bub2Δmad2Δ and bfa1Δmad2Δ cells formed rings at the same time with and without nocodazole. To determine if Bub2 has an effect on actomyosin ring contraction through its regulation of Tem1, we used live cell imaging of Myo1-GFP in a bub2Δ strain. We found a significant decrease in the total time of contraction and an increase in rate of contraction compared to wild type cells. We also examined myosin contraction using Myo1-GFP in cells overexpressing an epitope tagged Bub2. Surprisingly, overexpression of Bub2 also led to a significant increase in the rate of contraction, as well as morphological defects. The chained cell phenotype caused by Bub2 overexpression could be rescued by co-overexpression of Tem1, and was not rescued by deletion of BFA1. Conclusion Our data indicate that the Bub2 checkpoint pathway does not have a specific role in delaying actin ring formation. The observed increase in the rate of myosin contraction in the bub2Δ strain provides evidence that the MEN regulates actomyosin ring contraction. Our data suggest that the overexpression of the Bub2 fusion protein acts as a dominant negative, leading to septation defects by a mechanism that is Tem1-dependent.
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Affiliation(s)
- Su Young Park
- Department of Biological Sciences, Missouri University of Science and Technology, Rolla, MO, USA.
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41
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Yoshida S, Bartolini S, Pellman D. Mechanisms for concentrating Rho1 during cytokinesis. Genes Dev 2009; 23:810-23. [PMID: 19339687 DOI: 10.1101/gad.1785209] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The small GTP-binding protein, Rho1/RhoA plays a central role in cytokinetic actomyosin ring (CAR) assembly and cytokinesis. Concentration of Rho proteins at the division site is a general feature of cytokinesis, yet the mechanisms for recruiting Rho to the division site for cytokinesis remain poorly understood. We find that budding yeast utilizes two mechanisms to concentrate Rho1 at the division site. During anaphase, the primary mechanism for recruiting Rho1 is binding to its guanine nucleotide exchange factors (GEFs). GEF-dependent recruitment requires that Rho1 has the ability to pass through its GDP or unliganded state prior to being GTP-loaded. We were able to test this model by generating viable yeast lacking all identifiable Rho1 GEFs. Later, during septation and abscission, a second GEF-independent mechanism contributes to Rho1 bud neck targeting. This GEF-independent mechanism requires the Rho1 polybasic sequence that binds to acidic phospholipids, including phosphatidylinositol 4,5-bisphosphate (PIP2). This latter mechanism is functionally important because Rho1 activation or increased cellular levels of PIP2 promote cytokinesis in the absence of a contractile ring. These findings comprehensively define the targeting mechanisms of Rho1 essential for cytokinesis in yeast, and are likely to be relevant to cytokinesis in other organisms.
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Affiliation(s)
- Satoshi Yoshida
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Division of Hematology/Oncology, Children's Hospital Boston, Boston, Massachusetts 02115, USA
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42
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Abstract
Saccharomyces cerevisiae Chs2 (chitin synthase 2) synthesizes the primary septum after mitosis is completed. It is essential for proper cell separation and is expected to be highly regulated. We have expressed Chs2 and a mutant lacking the N-terminal region in Pichia pastoris in an active form at high levels. Both constructs show a pH and cation dependence similar to the wild-type enzyme, as well as increased activity after trypsin treatment. Using further biochemical analysis, we have identified two mechanisms of chitin synthase regulation. First, it is hyperactivated by a soluble yeast protease. This protease is expressed during exponential growth phase, when budding cells require Chs2 activity. Secondly, LC-MS/MS (liquid chromatography tandem MS) experiments on purified Chs2 identify 12 phosphorylation sites, all in the N-terminal domain. Four of them show the perfect sequence motif for phosphorylation by the cyclin-dependent kinase Cdk1. As we also show that phosphorylation of the N-terminal domain is important for Chs2 stability, these sites might play an important role in the cell cycle-dependent degradation of the enzyme, and thus in cell division.
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43
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Abstract
Throughout normal development, and in aberrant conditions such as cancer, cells divide by a process called cytokinesis. Most textbooks suggest that animal cells execute cytokinesis using an actomyosin-containing contractile ring, whereas plant cells generate a new cell wall by the assembly of a novel membrane compartment using vesicle-trafficking machinery in an apparently distinct manner. Recent studies have shown that cytokinesis in animal and plant cells may not be as distinct as these models imply - both have an absolute requirement for vesicle traffic. Moreover, some of the key molecular components of cytokinesis have been identified, many of which are proteins that function to control membrane traffic. Here, we review recent advances in this area.
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Affiliation(s)
- Rytis Prekeris
- Department of Cellular and Developmental Biology, School of Medicine, University of Colorado Health Sciences Center, 12801 E. 17th Avenue, Aurora, CO 80045, USA
| | - Gwyn W. Gould
- Henry Wellcome Laboratory of Cell Biology, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
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44
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Inn1 couples contraction of the actomyosin ring to membrane ingression during cytokinesis in budding yeast. Nat Cell Biol 2008; 10:395-406. [PMID: 18344988 DOI: 10.1038/ncb1701] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Accepted: 02/21/2008] [Indexed: 01/26/2023]
Abstract
By rapidly depleting each of the essential budding yeast proteins of unknown function, we identified a novel factor that we call Inn1, which associates with the contractile actomyosin ring at the end of mitosis and is needed for cytokinesis. We show that Inn1 has a C2 domain at the amino terminus of the protein that is required for ingression of the plasma membrane, whereas the remainder of the protein recruits Inn1 to the actomyosin ring. The lethal effects of deleting the INN1 gene can be suppressed by artificial fusion of the C2 domain to other components of the actomyosin ring, restoring membrane ingression on contraction of the actomyosin ring. Our data indicate that recruitment of the C2 domain of Inn1 to the contractile actomyosin ring is crucial for ingression of the plasma membrane during cytokinesis in budding yeast.
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45
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Fearon P, Cohen-Fix O. The endoplasmic reticulum takes center stage in cell cycle regulation. Sci Signal 2008; 1:pe4. [PMID: 18272469 DOI: 10.1126/stke.13pe4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Cell cycle progression is controlled by the action of cyclins and their partners, the cyclin-dependent kinases (CDKs). Although many of the cyclin/CDK targets are in the nucleus, some cyclins spend part of their time in the cytoplasm. Until recently, it was not clear what happens to these cyclins while they are in the cytoplasm; now, two different cyclins have been found to be associated with the endoplasmic reticulum. The question is why.
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Affiliation(s)
- Paula Fearon
- Laboratory of Molecular and Cellular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
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46
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Lee MCS, Miller EA. Molecular mechanisms of COPII vesicle formation. Semin Cell Dev Biol 2007; 18:424-34. [PMID: 17686639 DOI: 10.1016/j.semcdb.2007.06.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Accepted: 06/29/2007] [Indexed: 10/23/2022]
Abstract
The first step in protein secretion from eukaryotic cells is mediated by COPII vesicles, known for the cytoplasmic coat proteins that are the minimal machinery required to generate these small transport carriers. The five COPII coat components coordinate to create a vesicle by locally generating membrane curvature and populating the incipient bud with the appropriate cargo. This review describes the molecular details of how the COPII coat sculpts vesicles from the endoplasmic reticulum and highlights some unresolved questions regarding the regulation of this process in the complex environment of the eukaryotic cell.
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Affiliation(s)
- Marcus C S Lee
- Department of Microbiology, Columbia University, New York, NY, United States
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47
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Current awareness on yeast. Yeast 2007. [DOI: 10.1002/yea.1324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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