1
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Singh D, Liu Y, Zhu YH, Zhang S, Naegele S, Wu JQ. Septins function in exocytosis via physical interactions with the exocyst complex in fission yeast cytokinesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.09.602728. [PMID: 39026698 PMCID: PMC11257574 DOI: 10.1101/2024.07.09.602728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Septins can function as scaffolds for protein recruitment, membrane-bound diffusion barriers, or membrane curvature sensors. Septins are important for cytokinesis, but their exact roles are still obscure. In fission yeast, four septins (Spn1 to Spn4) accumulate at the rim of the division plane as rings. The octameric exocyst complex, which tethers exocytic vesicles to the plasma membrane, exhibits a similar localization and is essential for plasma membrane deposition during cytokinesis. Without septins, the exocyst spreads across the division plane but absent from the rim during septum formation. These results suggest that septins and the exocyst physically interact for proper localization. Indeed, we predicted six pairs of direct interactions between septin and exocyst subunits by AlphaFold2 ColabFold, most of them are confirmed by co-immunoprecipitation and yeast two-hybrid assays. Exocyst mislocalization results in mistargeting of secretory vesicles and their cargos, which leads to cell-separation delay in septin mutants. Our results indicate that septins guide the targeting of exocyst complex on the plasma membrane for vesicle tethering during cytokinesis through direct physical interactions.
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Affiliation(s)
- Davinder Singh
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States
| | - Yajun Liu
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States
| | - Yi-Hua Zhu
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States
| | - Sha Zhang
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States
| | - Shelby Naegele
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, Ohio, United States
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2
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Rezig IM, Yaduma WG, Gould GW, McInerny CJ. The role of anillin/Mid1p during medial division and cytokinesis: from fission yeast to cancer cells. Cell Cycle 2023; 22:633-644. [PMID: 36426865 PMCID: PMC9980708 DOI: 10.1080/15384101.2022.2147655] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Cytokinesis is the final stage of cell division cycle when cellular constituents are separated to produce two daughter cells. This process is driven by the formation and constriction of a contractile ring. Progression of these events is controlled by mechanisms and proteins that are evolutionary conserved in eukaryotes from fungi to humans. Genetic and molecular studies in different model organisms identified essential cytokinesis genes, with several conserved proteins, including the anillin/Mid1p proteins, constituting the core cytokinetic machinery. The fission yeast Schizosaccharomyces pombe represents a well-established model organism to study eukaryotic cell cycle regulation. Cytokinesis in fission yeast and mammalian cells depends on the placement, assembly, maturation, and constriction of a medially located actin-myosin contractile ring (ACR). Here, we review aspects of the ACR assembly and cytokinesis process in fission yeast and consider the regulation of such events in mammalian cells. First, we briefly describe the role of anillin during mammalian ACR assembly and cytokinesis. Second, we describe different aspects of the anillin-like protein Mid1p regulation during the S. pombe cell cycle, including its structure, function, and phospho-regulation. Third, we briefly discuss Mid1pindependent ACR assembly in S. pombe. Fourth, we highlight emerging studies demonstrating the roles of anillin in human tumourigenesis introducing anillin as a potential drug target for cancer treatment. Collectively, we provide an overview of the current understanding of medial division and cytokinesis in S. pombe and suggest the implications of these observations in other eukaryotic organisms, including humans.
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Affiliation(s)
- Imane M. Rezig
- School of Molecular Biosciences, College of Medical, Veterinary and Life Sciences, Davidson Building, University of Glasgow, Glasgow, UK
| | - Wandiahyel G. Yaduma
- School of Molecular Biosciences, College of Medical, Veterinary and Life Sciences, Davidson Building, University of Glasgow, Glasgow, UK,Department of Chemistry, School of Sciences, Adamawa State College of Education Hong, Nigeria
| | - Gwyn W. Gould
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Christopher J. McInerny
- School of Molecular Biosciences, College of Medical, Veterinary and Life Sciences, Davidson Building, University of Glasgow, Glasgow, UK,CONTACT Christopher J. McInerny School of Molecular Biosciences, College of Medical, Veterinary and Life Sciences, Davidson Building, University of Glasgow, GlasgowG12 8QQ, UK
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3
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Sayyad WA, Pollard TD. The number of cytokinesis nodes in mitotic fission yeast scales with cell size. eLife 2022; 11:76249. [PMID: 36093997 PMCID: PMC9467510 DOI: 10.7554/elife.76249] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 08/18/2022] [Indexed: 11/22/2022] Open
Abstract
Cytokinesis nodes are assemblies of stoichiometric ratios of proteins associated with the plasma membrane, which serve as precursors for the contractile ring during cytokinesis by fission yeast. The total number of nodes is uncertain, because of the limitations of the methods used previously. Here, we used the ~140 nm resolution of Airyscan super-resolution microscopy to measure the fluorescence intensity of small, single cytokinesis nodes marked with Blt1-mEGFP in live fission yeast cells early in mitosis. The ratio of the total Blt1-mEGFP fluorescence in the broad band of cytokinesis nodes to the average fluorescence of a single node gives about 190 single cytokinesis nodes in wild-type fission yeast cells early in mitosis. Most, but not all of these nodes condense into a contractile ring. The number of cytokinesis nodes scales with cell size in four strains tested, although large diameter rga4Δ mutant cells form somewhat fewer cytokinesis nodes than expected from the overall trend. The Pom1 kinase restricts cytokinesis nodes from the ends of cells, but the surface density of Pom1 on the plasma membrane around the equators of cells is similar with a wide range of node numbers, so Pom1 does not control cytokinesis node number. However, when the concentrations of either kinase Pom1 or kinase Cdr2 were varied with the nmt1 promoter, the numbers of cytokinesis nodes increased above a baseline of about ~190 with the total cellular concentration of either kinase.
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Affiliation(s)
- Wasim A Sayyad
- Department of Molecular Cellular and Developmental Biology,Yale University, New Haven, United States
| | - Thomas D Pollard
- Department of Molecular Cellular and Developmental Biology,Yale University, New Haven, United States.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States.,Department of Cell Biology,Yale University, New Haven, United States
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4
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Vicente-Soler J, Soto T, Franco A, Cansado J, Madrid M. The Multiple Functions of Rho GTPases in Fission Yeasts. Cells 2021; 10:1422. [PMID: 34200466 PMCID: PMC8228308 DOI: 10.3390/cells10061422] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 01/20/2023] Open
Abstract
The Rho family of GTPases represents highly conserved molecular switches involved in a plethora of physiological processes. Fission yeast Schizosaccharomyces pombe has become a fundamental model organism to study the functions of Rho GTPases over the past few decades. In recent years, another fission yeast species, Schizosaccharomyces japonicus, has come into focus offering insight into evolutionary changes within the genus. Both fission yeasts contain only six Rho-type GTPases that are spatiotemporally controlled by multiple guanine-nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), and whose intricate regulation in response to external cues is starting to be uncovered. In the present review, we will outline and discuss the current knowledge and recent advances on how the fission yeasts Rho family GTPases regulate essential physiological processes such as morphogenesis and polarity, cellular integrity, cytokinesis and cellular differentiation.
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Affiliation(s)
| | | | | | - José Cansado
- Yeast Physiology Group, Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain; (J.V.-S.); (T.S.); (A.F.)
| | - Marisa Madrid
- Yeast Physiology Group, Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain; (J.V.-S.); (T.S.); (A.F.)
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5
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Magliozzi JO, Sears J, Cressey L, Brady M, Opalko HE, Kettenbach AN, Moseley JB. Fission yeast Pak1 phosphorylates anillin-like Mid1 for spatial control of cytokinesis. J Cell Biol 2021; 219:151784. [PMID: 32421151 PMCID: PMC7401808 DOI: 10.1083/jcb.201908017] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 03/09/2020] [Accepted: 04/28/2020] [Indexed: 12/17/2022] Open
Abstract
Protein kinases direct polarized growth by regulating the cytoskeleton in time and space and could play similar roles in cell division. We found that the Cdc42-activated polarity kinase Pak1 colocalizes with the assembling contractile actomyosin ring (CAR) and remains at the division site during septation. Mutations in pak1 led to defects in CAR assembly and genetic interactions with cytokinesis mutants. Through a phosphoproteomic screen, we identified novel Pak1 substrates that function in polarized growth and cytokinesis. For cytokinesis, we found that Pak1 regulates the localization of its substrates Mid1 and Cdc15 to the CAR. Mechanistically, Pak1 phosphorylates the Mid1 N-terminus to promote its association with cortical nodes that act as CAR precursors. Defects in Pak1-Mid1 signaling lead to misplaced and defective division planes, but these phenotypes can be rescued by synthetic tethering of Mid1 to cortical nodes. Our work defines a new signaling mechanism driven by a cell polarity kinase that promotes CAR assembly in the correct time and place.
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Affiliation(s)
- Joseph O Magliozzi
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH
| | - Jack Sears
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH.,Norris Cotton Cancer Center, The Geisel School of Medicine at Dartmouth, Lebanon, NH
| | - Lauren Cressey
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH.,Norris Cotton Cancer Center, The Geisel School of Medicine at Dartmouth, Lebanon, NH
| | - Marielle Brady
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH
| | - Hannah E Opalko
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH
| | - Arminja N Kettenbach
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH.,Norris Cotton Cancer Center, The Geisel School of Medicine at Dartmouth, Lebanon, NH
| | - James B Moseley
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH
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6
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Kashiwazaki J, Yoneda Y, Mutoh T, Arai R, Yoshida M, Mabuchi I. A unique kinesin-like protein, Klp8, is involved in mitosis and cell morphology through microtubule stabilization. Cytoskeleton (Hoboken) 2019; 76:355-367. [PMID: 31276301 DOI: 10.1002/cm.21551] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 05/23/2019] [Accepted: 07/01/2019] [Indexed: 11/10/2022]
Abstract
Kinesins are microtubule (MT)-based motors involved in various cellular functions including intracellular transport of vesicles and organelles, and dynamics of chromosomes during cell division. The fission yeast Schizosaccharomyces pombe expresses nine kinesin-like proteins (klps). Klp8 is one of them and has not been characterized yet though it has been reported to localize at the division site. Here, we studied function and localization of Klp8 in S. pombe cells. The gene klp8+ was not essential for both viability and cytoskeletal organization. Klp8-YFP was concentrated as medial cortical dots during interphase, and organized into a ring at the division site during mitosis. The Klp8 ring seemed to be localized in the space between the actomyosin contractile ring and the plasma membrane. The Klp8 ring shrank as cytokinesis proceeded. In klp8-deleted (Δ) cells, the speed of spindle elongation during anaphase B was slowed down. Overproduction of Klp8 caused bent or elongated cells, in which MTs were abnormally elongated and less dynamic than those in normal cells. Deletion of klp8+ gene suppressed the delay in mitotic entry in blt1Δ cells. These results suggest that Klp8 is involved in mitosis and cell morphology through MT stabilization.
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Affiliation(s)
- Jun Kashiwazaki
- Department of Life Science, Gakushuin University, Tokyo, Japan
| | - Yumi Yoneda
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Tadashi Mutoh
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Ritsuko Arai
- Chemical Genetics Laboratory, RIKEN, Wako, Japan
| | - Minoru Yoshida
- Chemical Genetics Laboratory, RIKEN, Wako, Japan.,CREST Research Project, Japan Science and Technology Corporation, Wako, Japan
| | - Issei Mabuchi
- Department of Life Science, Gakushuin University, Tokyo, Japan.,Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
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7
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Leong SL, Lynch EM, Zou J, Tay YD, Borek WE, Tuijtel MW, Rappsilber J, Sawin KE. Reconstitution of Microtubule Nucleation In Vitro Reveals Novel Roles for Mzt1. Curr Biol 2019; 29:2199-2207.e10. [PMID: 31287970 PMCID: PMC6616311 DOI: 10.1016/j.cub.2019.05.058] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 04/29/2019] [Accepted: 05/23/2019] [Indexed: 12/25/2022]
Abstract
Microtubule (MT) nucleation depends on the γ-tubulin complex (γ-TuC), in which multiple copies of the heterotetrameric γ-tubulin small complex (γ-TuSC) associate to form a ring-like structure (in metazoans, γ-tubulin ring complex; γ-TuRC) [1-7]. Additional conserved regulators of the γ-TuC include the small protein Mzt1 (MOZART1 in human; GIP1/1B and GIP2/1A in plants) [8-13] and proteins containing a Centrosomin Motif 1 (CM1) domain [10, 14-19]. Many insights into γ-TuC regulators have come from in vivo analysis in fission yeast Schizosaccharomyces pombe. The S. pombe CM1 protein Mto1 recruits the γ-TuC to microtubule-organizing centers (MTOCs) [14, 20-22], and analysis of Mto1[bonsai], a truncated version of Mto1 that cannot localize to MTOCs, has shown that Mto1 also has a role in γ-TuC activation [23]. S. pombe Mzt1 interacts with γ-TuSC and is essential for γ-TuC function and localization to MTOCs [11, 12]. However, the mechanisms by which Mzt1 functions remain unclear. Here we describe reconstitution of MT nucleation using purified recombinant Mto1[bonsai], the Mto1 partner protein Mto2, γ-TuSC, and Mzt1. Multiple copies of the six proteins involved coassemble to form a 34-40S ring-like "MGM" holocomplex that is a potent MT nucleator in vitro. Using purified MGM and subcomplexes, we investigate the role of Mzt1 in MT nucleation. Our results suggest that Mzt1 is critical to stabilize Alp6, the S. pombe homolog of human γ-TuSC protein GCP3, in an "interaction-competent" form within the γ-TuSC. This is essential for MGM to become a functional nucleator.
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Affiliation(s)
- Su Ling Leong
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Eric M Lynch
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Juan Zou
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Ye Dee Tay
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Weronika E Borek
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Maarten W Tuijtel
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Juri Rappsilber
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK; Chair of Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, Berlin 13355, Germany
| | - Kenneth E Sawin
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK.
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8
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Arbizzani F, Rincon SA, Paoletti A. Increasing ergosterol levels delays formin-dependent assembly of F-actin cables and disrupts division plane positioning in fission yeast. J Cell Sci 2019; 132:jcs.227447. [PMID: 31217286 DOI: 10.1242/jcs.227447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 05/31/2019] [Indexed: 11/20/2022] Open
Abstract
In most eukaryotes, cytokinesis is mediated by the constriction of a contractile acto-myosin ring (CR), which promotes the ingression of the cleavage furrow. Many components of the CR interact with plasma membrane lipids suggesting that lipids may regulate CR assembly and function. Although there is clear evidence that phosphoinositides play an important role in cytokinesis, much less is known about the role of sterols in this process. Here, we studied how sterols influence division plane positioning and CR assembly in fission yeast. We show that increasing ergosterol levels in the plasma membrane blocks the assembly of F-actin cables from cytokinetic precursor nodes, preventing their compaction into a ring. Abnormal F-actin cables form after a delay, leading to randomly placed septa. Since the formin Cdc12 was detected on cytokinetic precursors and the phenotype can be partially rescued by inhibiting the Arp2/3 complex, which competes with formins for F-actin nucleation, we propose that ergosterol may inhibit formin dependent assembly of F-actin cables from cytokinetic precursors.
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Affiliation(s)
| | - Sergio A Rincon
- Institut Curie, PSL University, CNRS UMR 144, 75005 Paris, France .,Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, Salamanca 37007, Spain
| | - Anne Paoletti
- Institut Curie, PSL University, CNRS UMR 144, 75005 Paris, France
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9
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Chatterjee M, Pollard TD. The Functionally Important N-Terminal Half of Fission Yeast Mid1p Anillin Is Intrinsically Disordered and Undergoes Phase Separation. Biochemistry 2019; 58:3031-3041. [PMID: 31243991 DOI: 10.1021/acs.biochem.9b00217] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Division of fungal and animal cells depends on scaffold proteins called anillins. Cytokinesis by the fission yeast Schizosaccharomyces pombe is compromised by the loss of anillin Mid1p (Mid1, UniProtKB P78953 ), because cytokinesis organizing centers, called nodes, are misplaced and fail to acquire myosin-II, so they assemble slowly into abnormal contractile rings. The C-terminal half of Mid1p consists of lipid binding C2 and PH domains, but the N-terminal half (Mid1p-N452) performs most of the functions of the full-length protein. Little is known about the structure of the N-terminal half of Mid1p, so we investigated its physical properties using structure prediction tools, spectroscopic techniques, and hydrodynamic measurements. The data indicate that Mid1p-N452 is intrinsically disordered but moderately compact. Recombinant Mid1p-N452 purified from insect cells was phosphorylated, which weakens its tendency to aggregate. Purified Mid1p-N452 demixes into liquid droplets at concentrations far below its concentration in nodes. These physical properties are appropriate for scaffolding other proteins in nodes.
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10
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Mangione MC, Gould KL. Molecular form and function of the cytokinetic ring. J Cell Sci 2019; 132:132/12/jcs226928. [PMID: 31209062 DOI: 10.1242/jcs.226928] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Animal cells, amoebas and yeast divide using a force-generating, actin- and myosin-based contractile ring or 'cytokinetic ring' (CR). Despite intensive research, questions remain about the spatial organization of CR components, the mechanism by which the CR generates force, and how other cellular processes are coordinated with the CR for successful membrane ingression and ultimate cell separation. This Review highlights new findings about the spatial relationship of the CR to the plasma membrane and the arrangement of molecules within the CR from studies using advanced microscopy techniques, as well as mechanistic information obtained from in vitro approaches. We also consider advances in understanding coordinated cellular processes that impact the architecture and function of the CR.
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Affiliation(s)
- MariaSanta C Mangione
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
| | - Kathleen L Gould
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
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11
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Willet AH, DeWitt AK, Beckley JR, Clifford DM, Gould KL. NDR Kinase Sid2 Drives Anillin-like Mid1 from the Membrane to Promote Cytokinesis and Medial Division Site Placement. Curr Biol 2019; 29:1055-1063.e2. [PMID: 30853434 DOI: 10.1016/j.cub.2019.01.075] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 01/09/2019] [Accepted: 01/29/2019] [Indexed: 11/18/2022]
Abstract
In animals and fungi, cytokinesis is facilitated by the constriction of an actomyosin contractile ring (CR) [1]. In Schizosaccharomyces pombe, the CR forms mid-cell during mitosis from clusters of proteins at the medial cell cortex called nodes [2]. The anillin-like protein Mid1 localizes to nodes and is required for CR assembly at mid-cell [3]. When CR constriction begins, Mid1 leaves the division site. How Mid1 disassociates and whether this step is important for cytokinetic progression has been unknown. The septation initiation network (SIN), analogous to the Hippo pathway of multicellular organisms, is a signaling cascade that triggers node dispersal, CR assembly and constriction, and septum formation [4, 5]. We report that the terminal SIN kinase, Sid2 [6], phosphorylates Mid1 to drive its removal from the cortex at CR constriction onset. A Mid1 mutant that cannot be phosphorylated by Sid2 remains cortical during cytokinesis, over-accumulates in interphase nodes following cell division in a manner dependent on the SAD kinase Cdr2, advances the G2/M transition, precociously recruits other CR components to nodes, pulls Cdr2 aberrantly into the CR, and reduces rates of CR maturation and constriction. When combined with cdr2 mutants that affect node assembly or disassembly, gross defects in division site positioning result. Our findings identify Mid1 as a key Sid2 substrate for SIN-mediated remodeling of the division site for efficient cytokinesis and provide evidence that nodes serve to integrate signals coordinating cell cycle progression and cytokinesis.
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Affiliation(s)
- Alaina H Willet
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Ashley K DeWitt
- Grand Valley State University, Department of Cell and Molecular Biology, Allendale, MI 49401, USA
| | - Janel R Beckley
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Dawn M Clifford
- Grand Valley State University, Department of Cell and Molecular Biology, Allendale, MI 49401, USA
| | - Kathleen L Gould
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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12
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Kwon L, Magee EM, Crayton A, Goss JW. Fission yeast type 2 node proteins Blt1p and Gef2p cooperate to ensure timely completion of cytokinesis. BMC Mol Cell Biol 2019; 20:1. [PMID: 31041892 PMCID: PMC6446504 DOI: 10.1186/s12860-018-0182-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 12/14/2018] [Indexed: 12/01/2022] Open
Abstract
Background The conserved NDR-family kinase Sid2p localizes to the contractile ring during fission yeast cytokinesis to promote ring constriction, septation, and completion of cell division. Previous studies have found that the Type 2 interphase node proteins Blt1p and Gef2p contribute to localization of Sid2p and its regulatory protein Mob1p at the division site. However, their relative contributions and whether they operate in the same or parallel pathways has been unclear. In this study, we quantify the respective roles of Blt1p and Gef2p in Sid2p/Mob1p recruitment and characterize the effect of single and double deletion mutants on contractile ring dynamics and completion of cell division. Results Using quantitative confocal fluorescence microscopy, we measured Sid2p and Mob1p recruitment to the division site in blt1∆, gef2∆, and blt1∆/gef2∆ mutant cells. We observed an equivalent decrease in Sid2p/Mob1p localization for both single and double mutants. Though assembly of the contractile ring is normal in these mutants, the reduction in Sid2p/Mob1p at the division site delayed the onset of contractile ring constriction and completion of division. We quantified localization of Blt1p and Gef2p at the medial cortex throughout the cell cycle and found that Blt1p localization to interphase nodes and the contractile ring is independent of Gef2p. However, Gef2p localization to the contractile ring is decreased in blt1∆ mutants. Conclusions Blt1p and Gef2p work in the same pathway, rather than in parallel, to localize the NDR-family kinase Sid2p and its regulatory partner Mob1p to the division site, thereby promoting timely completion of cell division. Future studies are necessary to understand how additional fission yeast cytokinesis proteins work with these Type 2 interphase node components to promote Sid2p/Mob1p recruitment. Electronic supplementary material The online version of this article (10.1186/s12860-018-0182-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lois Kwon
- Department of Biological Sciences, Wellesley College, 106 Central Street, Wellesley, MA, 02481, USA
| | - Emma M Magee
- Department of Biological Sciences, Wellesley College, 106 Central Street, Wellesley, MA, 02481, USA
| | - Alexis Crayton
- Department of Biological Sciences, Wellesley College, 106 Central Street, Wellesley, MA, 02481, USA
| | - John W Goss
- Department of Biological Sciences, Wellesley College, 106 Central Street, Wellesley, MA, 02481, USA.
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13
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Molecular mechanisms of contractile-ring constriction and membrane trafficking in cytokinesis. Biophys Rev 2018; 10:1649-1666. [PMID: 30448943 DOI: 10.1007/s12551-018-0479-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 11/06/2018] [Indexed: 12/14/2022] Open
Abstract
In this review, we discuss the molecular mechanisms of cytokinesis from plants to humans, with a focus on contribution of membrane trafficking to cytokinesis. Selection of the division site in fungi, metazoans, and plants is reviewed, as well as the assembly and constriction of a contractile ring in fungi and metazoans. We also provide an introduction to exocytosis and endocytosis, and discuss how they contribute to successful cytokinesis in eukaryotic cells. The conservation in the coordination of membrane deposition and cytoskeleton during cytokinesis in fungi, metazoans, and plants is highlighted.
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14
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Akamatsu M, Lin Y, Bewersdorf J, Pollard TD. Analysis of interphase node proteins in fission yeast by quantitative and superresolution fluorescence microscopy. Mol Biol Cell 2017; 28:3203-3214. [PMID: 28539404 PMCID: PMC5687023 DOI: 10.1091/mbc.e16-07-0522] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 04/14/2017] [Accepted: 05/15/2017] [Indexed: 02/06/2023] Open
Abstract
We used quantitative confocal microscopy and FPALM superresolution microscopy of live fission yeast to investigate the structures and assembly of two types of interphase nodes-multiprotein complexes associated with the plasma membrane that merge together and mature into the precursors of the cytokinetic contractile ring. During the long G2 phase of the cell cycle, seven different interphase node proteins maintain constant concentrations as they accumulate in proportion to cell volume. During mitosis, the total numbers of type 1 node proteins (cell cycle kinases Cdr1p, Cdr2p, Wee1p, and anillin Mid1p) are constant even when the nodes disassemble. Quantitative measurements provide strong evidence that both types of nodes have defined sizes and numbers of constituent proteins, as observed for cytokinesis nodes. Type 1 nodes assemble in two phases-a burst at the end of mitosis, followed by steady increase during interphase to double the initial number. Type 2 nodes containing Blt1p, Rho-GEF Gef2p, and kinesin Klp8p remain intact throughout the cell cycle and are constituents of the contractile ring. They are released from the contractile ring as it disassembles and then associate with type 1 nodes around the equator of the cell during interphase.
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Affiliation(s)
- Matthew Akamatsu
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103.,Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, CT 06520-8103
| | - Yu Lin
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, CT 06520-8103.,Department of Cell Biology, Yale University, New Haven, CT 06520-8103.,Department of Biomedical Engineering, Yale University, New Haven, CT 06520-8103
| | - Joerg Bewersdorf
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, CT 06520-8103.,Department of Biomedical Engineering, Yale University, New Haven, CT 06520-8103
| | - Thomas D Pollard
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103 .,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103.,Department of Cell Biology, Yale University, New Haven, CT 06520-8103
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15
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Abstract
SUMMARYCell division-cytokinesis-involves large-scale rearrangements of the entire cell. Primarily driven by cytoskeletal proteins, cytokinesis also depends on topological rearrangements of the plasma membrane, which are coordinated with nuclear division in both space and time. Despite the fundamental nature of the process, different types of eukaryotic cells show variations in both the structural mechanisms of cytokinesis and the regulatory controls. In animal cells and fungi, a contractile actomyosin-based structure plays a central, albeit flexible, role. Here, the underlying molecular mechanisms are summarized and integrated and common themes are highlighted.
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Affiliation(s)
- Michael Glotzer
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637
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16
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Rincon SA, Estravis M, Dingli F, Loew D, Tran PT, Paoletti A. SIN-Dependent Dissociation of the SAD Kinase Cdr2 from the Cell Cortex Resets the Division Plane. Curr Biol 2017; 27:534-542. [PMID: 28162898 DOI: 10.1016/j.cub.2016.12.050] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 11/28/2016] [Accepted: 12/22/2016] [Indexed: 11/16/2022]
Abstract
Proper division plane positioning is crucial for faithful chromosome segregation but also influences cell size, position, or fate [1]. In fission yeast, medial division is controlled through negative signaling by the cell tips during interphase and positive signaling by the centrally placed nucleus at mitotic entry [2-4]: the cell geometry network (CGN), controlled by the inhibitory cortical gradient of the DYRK kinase Pom1 emanating from the cell tips, first promotes the medial localization of cytokinetic ring precursors organized by the SAD kinase Cdr2 to pre-define the division plane [5-8]; then, massive nuclear export of the anillin-like protein Mid1 at mitosis entry confirms or readjusts the division plane according to nuclear position and triggers the assembly of a medial contractile ring [5, 9-11]. Strikingly, the Hippo-like septation initiation network (SIN) induces Cdr2 dissociation from cytokinetic precursors at this stage [12-14]. We show here that SIN-dependent phosphorylation of Cdr2 promotes its interaction with the 14-3-3 protein Rad24 that sequesters it in the cytoplasm during cell division. If this interaction is compromised, cytokinetic precursors are asymmetrically distributed in the cortex of newborn cells, leading to asymmetrical division if nuclear signaling is abolished. We conclude that, through this new function, the SIN resets the division plane in newborn cells to ensure medial division.
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Affiliation(s)
- Sergio A Rincon
- Institut Curie, PSL Research University, CNRS, UMR 144, 75005 Paris, France.
| | - Miguel Estravis
- Institute of Genetics and Development of Rennes, CNRS, UMR 6290, 35043 Rennes Cedex, France
| | - Florent Dingli
- Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, 75005 Paris, France
| | - Damarys Loew
- Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, 75005 Paris, France
| | - Phong T Tran
- Institut Curie, PSL Research University, CNRS, UMR 144, 75005 Paris, France; Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anne Paoletti
- Institut Curie, PSL Research University, CNRS, UMR 144, 75005 Paris, France.
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17
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Davidson R, Pontasch JA, Wu JQ. Sbg1 Is a Novel Regulator for the Localization of the β-Glucan Synthase Bgs1 in Fission Yeast. PLoS One 2016; 11:e0167043. [PMID: 27898700 PMCID: PMC5127554 DOI: 10.1371/journal.pone.0167043] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Accepted: 11/08/2016] [Indexed: 02/03/2023] Open
Abstract
Glucan synthases synthesize glucans, complex polysaccharides that are the major components in fungal cell walls and division septa. Studying regulation of glucan synthases is important as they are essential for fungal cell survival and thus popular targets for anti-fungal drugs. Linear 1,3-β-glucan is the main component of primary septum and is synthesized by the conserved β-glucan synthase Bgs1 in fission yeast cytokinesis. It is known that Rho1 GTPase regulates Bgs1 catalytic activity and the F-BAR protein Cdc15 plays a role in Bgs1 delivery to the plasma membrane. Here we characterize a novel protein Sbg1 that is present in a complex with Bgs1 and regulates its protein levels and localization. Sbg1 is essential for contractile-ring constriction and septum formation during cytokinesis. Sbg1 and Bgs1 physically interact and are interdependent for localization to the plasma membrane. Bgs1 is less stable and/or mis-targeted to vacuoles in sbg1 mutants. Moreover, Sbg1 plays an earlier and more important role in Bgs1 trafficking and localization than Cdc15. Together, our data reveal a new mode of regulation for the essential β-glucan synthase Bgs1 by the novel protein Sbg1.
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Affiliation(s)
- Reshma Davidson
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
| | - Josef A. Pontasch
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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18
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Yasuda T, Takaine M, Numata O, Nakano K. Anillin-related protein Mid1 regulates timely formation of the contractile ring in the fission yeastSchizosaccharomyces japonicus. Genes Cells 2016; 21:594-607. [DOI: 10.1111/gtc.12368] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Accepted: 03/03/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Tsuyoshi Yasuda
- Department of Biological Sciences; Graduate School of Life and Environmental Sciences; University of Tsukuba; Tsukuba Ibaraki 305-8572 Japan
| | - Masak Takaine
- Department of Biological Sciences; Graduate School of Life and Environmental Sciences; University of Tsukuba; Tsukuba Ibaraki 305-8572 Japan
| | - Osamu Numata
- Department of Biological Sciences; Graduate School of Life and Environmental Sciences; University of Tsukuba; Tsukuba Ibaraki 305-8572 Japan
| | - Kentaro Nakano
- Department of Biological Sciences; Graduate School of Life and Environmental Sciences; University of Tsukuba; Tsukuba Ibaraki 305-8572 Japan
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19
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Rincon SA, Paoletti A. Molecular control of fission yeast cytokinesis. Semin Cell Dev Biol 2016; 53:28-38. [PMID: 26806637 DOI: 10.1016/j.semcdb.2016.01.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 01/06/2016] [Indexed: 12/29/2022]
Abstract
Cytokinesis gives rise to two independent daughter cells at the end of the cell division cycle. The fission yeast Schizosaccharomyces pombe has emerged as one of the most powerful systems to understand how cytokinesis is controlled molecularly. Like in most eukaryotes, fission yeast cytokinesis depends on an acto-myosin based contractile ring that assembles at the division site under the control of spatial cues that integrate information on cell geometry and the position of the mitotic apparatus. Cytokinetic events are also tightly coordinated with nuclear division by the cell cycle machinery. These spatial and temporal regulations ensure an equal cleavage of the cytoplasm and an accurate segregation of the genetic material in daughter cells. Although this model system has specificities, the basic mechanisms of contractile ring assembly and function deciphered in fission yeast are highly valuable to understand how cytokinesis is controlled in other organisms that rely on a contractile ring for cell division.
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Affiliation(s)
- Sergio A Rincon
- Institut Curie, Centre de Recherche, PSL Research University, F-75248 Paris, France; CNRS UMR144, F-75248 Paris, France
| | - Anne Paoletti
- Institut Curie, Centre de Recherche, PSL Research University, F-75248 Paris, France; CNRS UMR144, F-75248 Paris, France.
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20
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Guzmán-Vendrell M, Rincon SA, Dingli F, Loew D, Paoletti A. Molecular control of the Wee1 regulatory pathway by the SAD kinase Cdr2. J Cell Sci 2015; 128:2842-53. [PMID: 26071525 DOI: 10.1242/jcs.173146] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 06/10/2015] [Indexed: 01/14/2023] Open
Abstract
Cell growth and division are tightly coordinated to maintain cell size constant during successive cell cycles. In Schizosaccharomyces pombe, the SAD kinase Cdr2 regulates the cell size at division and the positioning of the division plane. Cdr2 forms nodes on the medial cortex containing factors that constitute an inhibitory pathway for Wee1. This pathway is regulated by polar gradients of the DYRK kinase Pom1, and involves a direct inhibitor of Wee1, the SAD kinase Cdr1. Cdr2 also interacts with the anillin Mid1, which defines the division plane, and with additional components of the medial cortical nodes, including Blt1, which participate in the mitotic-promoting and cytokinetic functions of nodes. Here, we show that the interaction of Cdr2 with Wee1 and Mid1 requires the UBA domain of Cdr2, which is necessary for its kinase activity. In contrast, Cdr1 associates with the C-terminus of Cdr2, which is composed of basic and KA-1 lipid-binding domains. Mid1 also interacts with the C-terminus of Cdr2 and might bridge the N- and C-terminal domains, whereas Blt1 associates with the central spacer region. We propose that the association of Cdr2 effectors with different domains might constrain Cdr1 and Wee1 spatially to promote Wee1 inhibition upon Cdr2 kinase activation.
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Affiliation(s)
- Mercè Guzmán-Vendrell
- Institut Curie, Centre de Recherche, PSL Research University, Paris F-75248, France CNRS UMR144, Paris F-75248, France
| | - Sergio A Rincon
- Institut Curie, Centre de Recherche, PSL Research University, Paris F-75248, France CNRS UMR144, Paris F-75248, France
| | - Florent Dingli
- Institut Curie, Centre de Recherche, PSL Research University, Paris F-75248, France Laboratory of Mass Spectrometry and Proteomics, Paris F-75248, France
| | - Damarys Loew
- Institut Curie, Centre de Recherche, PSL Research University, Paris F-75248, France Laboratory of Mass Spectrometry and Proteomics, Paris F-75248, France
| | - Anne Paoletti
- Institut Curie, Centre de Recherche, PSL Research University, Paris F-75248, France CNRS UMR144, Paris F-75248, France
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21
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Sun L, Guan R, Lee IJ, Liu Y, Chen M, Wang J, Wu JQ, Chen Z. Mechanistic insights into the anchorage of the contractile ring by anillin and Mid1. Dev Cell 2015; 33:413-26. [PMID: 25959226 DOI: 10.1016/j.devcel.2015.03.003] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 01/22/2015] [Accepted: 03/02/2015] [Indexed: 11/17/2022]
Abstract
Anillins and Mid1 are scaffold proteins that play key roles in anchorage of the contractile ring at the cell equator during cytokinesis in animals and fungi, respectively. Here, we report crystal structures and functional analysis of human anillin and S. pombe Mid1. The combined data show anillin contains a cryptic C2 domain and a Rho-binding domain. Together with the tethering PH domain, three membrane-associating elements synergistically bind to RhoA and phospholipids to anchor anillin at the cleavage furrow. Surprisingly, Mid1 also binds to the membrane through a cryptic C2 domain. Dimerization of Mid1 leads to high affinity and preference for PI(4,5)P2, which stably anchors Mid1 at the division plane, bypassing the requirement for Rho GTPase. These findings uncover the unexpected general machinery and the divergent regulatory logics for the anchorage of the contractile ring through the anillin/Mid1 family proteins from yeast to humans.
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Affiliation(s)
- Lingfei Sun
- MOE Key Laboratory of Protein Science, Tsinghua University, Beijing 100084, China; School of Life Science, Tsinghua University, Beijing 100084, China
| | - Ruifang Guan
- MOE Key Laboratory of Protein Science, Tsinghua University, Beijing 100084, China; School of Life Science, Tsinghua University, Beijing 100084, China
| | - I-Ju Lee
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Yajun Liu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Mengran Chen
- MOE Key Laboratory of Protein Science, Tsinghua University, Beijing 100084, China; School of Life Science, Tsinghua University, Beijing 100084, China
| | - Jiawei Wang
- School of Life Science, Tsinghua University, Beijing 100084, China; State Key Laboratory of Bio-membrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Zhucheng Chen
- MOE Key Laboratory of Protein Science, Tsinghua University, Beijing 100084, China; School of Life Science, Tsinghua University, Beijing 100084, China.
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22
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Davidson R, Laporte D, Wu JQ. Regulation of Rho-GEF Rgf3 by the arrestin Art1 in fission yeast cytokinesis. Mol Biol Cell 2014; 26:453-66. [PMID: 25473118 PMCID: PMC4310737 DOI: 10.1091/mbc.e14-07-1252] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The arrestin Art1 and the Rho1 guanine nucleotide exchange factor Rgf3 are interdependent for their localizations to the division site during fission yeast cytokinesis. Art1 physically interacts with Rgf3 to modulate active Rho1 GTPase levels for successful septal formation. Rho GTPases, activated by guanine nucleotide exchange factors (GEFs), are essential regulators of polarized cell growth, cytokinesis, and many other cellular processes. However, the regulation of Rho-GEFs themselves is not well understood. Rgf3 is an essential GEF for Rho1 GTPase in fission yeast. We show that Rgf3 protein levels and localization are regulated by arrestin-related protein Art1. art1∆ cells lyse during cell separation with a thinner and defective septum. As does Rgf3, Art1 concentrates to the contractile ring starting at early anaphase and spreads to the septum during and after ring constriction. Art1 localization depends on its C-terminus, and Art1 is important for maintaining Rgf3 protein levels. Biochemical experiments reveal that the Rgf3 C-terminus binds to Art1. Using an Rgf3 conditional mutant and mislocalization experiments, we found that Art1 and Rgf3 are interdependent for localization to the division site. As expected, active Rho1 levels at the division site are reduced in art1∆ and rgf3 mutant cells. Taken together, these data reveal that the arrestin family protein Art1 regulates the protein levels and localization of the Rho-GEF Rgf3, which in turn modulates active Rho1 levels during fission yeast cytokinesis.
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Affiliation(s)
- Reshma Davidson
- Graduate Program of Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, OH 43210 Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Damien Laporte
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210 Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH 43210
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23
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Wang N, Wang M, Zhu YH, Grosel TW, Sun D, Kudryashov DS, Wu JQ. The Rho-GEF Gef3 interacts with the septin complex and activates the GTPase Rho4 during fission yeast cytokinesis. Mol Biol Cell 2014; 26:238-55. [PMID: 25411334 PMCID: PMC4294672 DOI: 10.1091/mbc.e14-07-1196] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Rho GTPases, activated by Rho guanine nucleotide exchange factors (GEFs), are conserved molecular switches for signal transductions that regulate diverse cellular processes, including cell polarization and cytokinesis. The fission yeast Schizosaccharomyces pombe has six Rho GTPases (Cdc42 and Rho1-Rho5) and seven Rho GEFs (Scd1, Rgf1-Rgf3, and Gef1-Gef3). The GEFs for Rho2-Rho5 have not been unequivocally assigned. In particular, Gef3, the smallest Rho GEF, was barely studied. Here we show that Gef3 colocalizes with septins at the cell equator. Gef3 physically interacts with septins and anillin Mid2 and depends on them to localize. Gef3 coprecipitates with GDP-bound Rho4 in vitro and accelerates nucleotide exchange of Rho4, suggesting that Gef3 is a GEF for Rho4. Consistently, Gef3 and Rho4 are in the same genetic pathways to regulate septum formation and/or cell separation. In gef3∆ cells, the localizations of two potential Rho4 effectors--glucanases Eng1 and Agn1--are abnormal, and active Rho4 level is reduced, indicating that Gef3 is involved in Rho4 activation in vivo. Moreover, overexpression of active Rho4 or Eng1 rescues the septation defects of mutants containing gef3∆. Together our data support that Gef3 interacts with the septin complex and activates Rho4 GTPase as a Rho GEF for septation in fission yeast.
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Affiliation(s)
| | - Mo Wang
- Department of Molecular Genetics
| | | | | | | | | | - Jian-Qiu Wu
- Department of Molecular Genetics Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH 43210
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24
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Rincon SA, Bhatia P, Bicho C, Guzman-Vendrell M, Fraisier V, Borek WE, Alves FDL, Dingli F, Loew D, Rappsilber J, Sawin KE, Martin SG, Paoletti A. Pom1 regulates the assembly of Cdr2-Mid1 cortical nodes for robust spatial control of cytokinesis. ACTA ACUST UNITED AC 2014; 206:61-77. [PMID: 24982431 PMCID: PMC4085711 DOI: 10.1083/jcb.201311097] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pom1 regulation of Cdr2 membrane association and interaction with Mid1 prevents Cdr2 assembly into stable nodes in the cell tip region, which ensures proper positioning of cytokinetic ring precursors and accurate division plane positioning in fission yeast. Proper division plane positioning is essential to achieve faithful DNA segregation and to control daughter cell size, positioning, or fate within tissues. In Schizosaccharomyces pombe, division plane positioning is controlled positively by export of the division plane positioning factor Mid1/anillin from the nucleus and negatively by the Pom1/DYRK (dual-specificity tyrosine-regulated kinase) gradients emanating from cell tips. Pom1 restricts to the cell middle cortical cytokinetic ring precursor nodes organized by the SAD-like kinase Cdr2 and Mid1/anillin through an unknown mechanism. In this study, we show that Pom1 modulates Cdr2 association with membranes by phosphorylation of a basic region cooperating with the lipid-binding KA-1 domain. Pom1 also inhibits Cdr2 interaction with Mid1, reducing its clustering ability, possibly by down-regulation of Cdr2 kinase activity. We propose that the dual regulation exerted by Pom1 on Cdr2 prevents Cdr2 assembly into stable nodes in the cell tip region where Pom1 concentration is high, which ensures proper positioning of cytokinetic ring precursors at the cell geometrical center and robust and accurate division plane positioning.
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Affiliation(s)
- Sergio A Rincon
- Centre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, France Centre National de la Recherche Scientifique, Unite Mixte de Recherche 144, F-75248 Paris, France
| | - Payal Bhatia
- Department of Fundamental Microbiology, University of Lausanne, Lausanne CH-1015, Switzerland
| | - Claudia Bicho
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK
| | - Mercè Guzman-Vendrell
- Centre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, France Centre National de la Recherche Scientifique, Unite Mixte de Recherche 144, F-75248 Paris, France
| | - Vincent Fraisier
- Centre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, France Centre National de la Recherche Scientifique, Unite Mixte de Recherche 144, F-75248 Paris, France
| | - Weronika E Borek
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK
| | - Flavia de Lima Alves
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK
| | - Florent Dingli
- Centre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, FranceCentre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, France
| | - Damarys Loew
- Centre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, FranceCentre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, France
| | - Juri Rappsilber
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK
| | - Kenneth E Sawin
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK
| | - Sophie G Martin
- Department of Fundamental Microbiology, University of Lausanne, Lausanne CH-1015, Switzerland
| | - Anne Paoletti
- Centre de Recherche and Laboratory of Mass Spectrometry and Proteomics, Institut Curie, F-75248 Paris, France Centre National de la Recherche Scientifique, Unite Mixte de Recherche 144, F-75248 Paris, France
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25
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Muñoz S, Manjón E, Sánchez Y. The putative exchange factor Gef3p interacts with Rho3p GTPase and the septin ring during cytokinesis in fission yeast. J Biol Chem 2014; 289:21995-2007. [PMID: 24947517 DOI: 10.1074/jbc.m114.548792] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The small GTP-binding proteins of the Rho family and its regulatory proteins play a central role in cytokinetic actomyosin ring assembly and cytokinesis. Here we show that the fission yeast guanine nucleotide exchange factor Gef3p interacts with Rho3p at the division site. Gef3p contains a putative DH homology domain and a BAR/IMD-like domain. The protein localized to the division site late in mitosis, where it formed a ring that did not constrict with actomyosin ring (cytokinetic actomyosin ring) invagination; instead, it split into a double ring that resembled the septin ring. Gef3p co-localized with septins and Mid2p and required septins and Mid2p for its localization. Gef3p interacts physically with the GTP-bound form of Rho3p. Although Gef3p is not essential for cell separation, the simultaneous disruption of gef3(+) and Rho3p-interacting proteins, such as Sec8p, an exocyst component, Apm1p, a subunit of the clathrin adaptor complex or For3p, an actin-polymerizing protein, yielded cells with strong defects in septation and polarity respectively. Our results suggest that interactions between septins and Rho-GEFs provide a new targeting mechanism for GTPases in cytokinesis, in this case probably contributing to Rho3p function in vesicle tethering and vesicle trafficking in the later steps of cell separation.
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Affiliation(s)
- Sofía Muñoz
- From the Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas and Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Zacarías González, s/n. 37007 Salamanca, Spain
| | - Elvira Manjón
- From the Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas and Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Zacarías González, s/n. 37007 Salamanca, Spain
| | - Yolanda Sánchez
- From the Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas and Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Zacarías González, s/n. 37007 Salamanca, Spain
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26
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Akamatsu M, Berro J, Pu KM, Tebbs IR, Pollard TD. Cytokinetic nodes in fission yeast arise from two distinct types of nodes that merge during interphase. ACTA ACUST UNITED AC 2014; 204:977-88. [PMID: 24637325 PMCID: PMC3998791 DOI: 10.1083/jcb.201307174] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Two distinct classes of cortical nodes form separately during interphase in fission yeast cells and then merge at the cell equator by a diffuse-and-capture mechanism to prepare nodes to form the contractile ring for cytokinesis. We investigated the assembly of cortical nodes that generate the cytokinetic contractile ring in fission yeast. Observations of cells expressing fluorescent fusion proteins revealed two types of interphase nodes. Type 1 nodes containing kinase Cdr1p, kinase Cdr2p, and anillin Mid1p form in the cortex around the nucleus early in G2. Type 2 nodes with protein Blt1p, guanosine triphosphate exchange factor Gef2p, and kinesin Klp8p emerge from contractile ring remnants. Quantitative measurements and computer simulations showed that these two types of nodes come together by a diffuse-and-capture mechanism: type 2 nodes diffuse to the equator and are captured by stationary type 1 nodes. During mitosis, cytokinetic nodes with Mid1p and all of the type 2 node markers incorporate into the contractile ring, whereas type 1 nodes with Cdr1p and Cdr2p follow the separating nuclei before dispersing into the cytoplasm, dependent on septation initiation network signaling. The two types of interphase nodes follow parallel branches of the pathway to prepare nodes for cytokinesis.
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Affiliation(s)
- Matthew Akamatsu
- Department of Molecular, Cellular, and Developmental Biology, 2 Department of Molecular Biophysics and Biochemistry, 3 Nanobiology Institute, and 4 Department of Cell Biology, Yale University, New Haven, CT 06520
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Wang N, Lo Presti L, Zhu YH, Kang M, Wu Z, Martin SG, Wu JQ. The novel proteins Rng8 and Rng9 regulate the myosin-V Myo51 during fission yeast cytokinesis. ACTA ACUST UNITED AC 2014; 205:357-75. [PMID: 24798735 PMCID: PMC4018781 DOI: 10.1083/jcb.201308146] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The myosin-V family of molecular motors is known to be under sophisticated regulation, but our knowledge of the roles and regulation of myosin-Vs in cytokinesis is limited. Here, we report that the myosin-V Myo51 affects contractile ring assembly and stability during fission yeast cytokinesis, and is regulated by two novel coiled-coil proteins, Rng8 and Rng9. Both rng8Δ and rng9Δ cells display similar defects as myo51Δ in cytokinesis. Rng8 and Rng9 are required for Myo51's localizations to cytoplasmic puncta, actin cables, and the contractile ring. Myo51 puncta contain multiple Myo51 molecules and walk continuously on actin filaments in rng8(+) cells, whereas Myo51 forms speckles containing only one dimer and does not move efficiently on actin tracks in rng8Δ. Consistently, Myo51 transports artificial cargos efficiently in vivo, and this activity is regulated by Rng8. Purified Rng8 and Rng9 form stable higher-order complexes. Collectively, we propose that Rng8 and Rng9 form oligomers and cluster multiple Myo51 dimers to regulate Myo51 localization and functions.
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Affiliation(s)
- Ning Wang
- Department of Molecular Genetics, 2 Department of Molecular and Cellular Biochemistry, and 3 Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
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Goss JW, Kim S, Bledsoe H, Pollard TD. Characterization of the roles of Blt1p in fission yeast cytokinesis. Mol Biol Cell 2014; 25:1946-57. [PMID: 24790095 PMCID: PMC4072569 DOI: 10.1091/mbc.e13-06-0300] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Spatial and temporal regulation of cytokinesis is essential for cell division, yet the mechanisms that control the formation and constriction of the contractile ring are incompletely understood. In the fission yeast Schizosaccharomyces pombe proteins that contribute to the cytokinetic contractile ring accumulate during interphase in nodes-precursor structures around the equatorial cortex. During mitosis, additional proteins join these nodes, which condense to form the contractile ring. The cytokinesis protein Blt1p is unique in being present continuously in nodes from early interphase through to the contractile ring until cell separation. Blt1p was shown to stabilize interphase nodes, but its functions later in mitosis were unclear. We use analytical ultracentrifugation to show that purified Blt1p is a tetramer. We find that Blt1p interacts physically with Sid2p and Mob1p, a protein kinase complex of the septation initiation network, and confirm known interactions with F-BAR protein Cdc15p. Contractile rings assemble normally in blt1∆ cells, but the initiation of ring constriction and completion of cell division are delayed. We find three defects that likely contribute to this delay. Without Blt1p, contractile rings recruited and retained less Sid2p/Mob1p and Clp1p phosphatase, and β-glucan synthase Bgs1p accumulated slowly at the cleavage site.
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Affiliation(s)
- John W Goss
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103Department of Biological Sciences, Wellesley College, Wellesley, MA 02481-8203
| | - Sunhee Kim
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103
| | - Hannah Bledsoe
- Department of Biological Sciences, Wellesley College, Wellesley, MA 02481-8203
| | - Thomas D Pollard
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103Department of Cell Biology, Yale University, New Haven, CT 06520-8103
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Zhu YH, Ye Y, Wu Z, Wu JQ. Cooperation between Rho-GEF Gef2 and its binding partner Nod1 in the regulation of fission yeast cytokinesis. Mol Biol Cell 2013; 24:3187-204. [PMID: 23966468 PMCID: PMC3806657 DOI: 10.1091/mbc.e13-06-0301] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Previous results showed that putative Rho-GEF Gef2 regulates division-site positioning during early cytokinesis in fission yeast. Here Nod1 is identified as a binding partner of Gef2. The two proteins form a complex to regulate division-site positioning and contractile-ring maintenance. In addition, Gef2 binds to GTPases Rho1, Rho4, and Rho5 in vitro. Cytokinesis is the last step of the cell-division cycle, which requires precise spatial and temporal regulation to ensure genetic stability. Rho guanine nucleotide exchange factors (Rho GEFs) and Rho GTPases are among the key regulators of cytokinesis. We previously found that putative Rho-GEF Gef2 coordinates with Polo kinase Plo1 to control the medial cortical localization of anillin-like protein Mid1 in fission yeast. Here we show that an adaptor protein, Nod1, colocalizes with Gef2 in the contractile ring and its precursor cortical nodes. Like gef2∆, nod1∆ has strong genetic interactions with various cytokinesis mutants involved in division-site positioning, suggesting a role of Nod1 in early cytokinesis. We find that Nod1 and Gef2 interact through the C-termini, which is important for their localization. The contractile-ring localization of Nod1 and Gef2 also depends on the interaction between Nod1 and the F-BAR protein Cdc15, where the Nod1/Gef2 complex plays a role in contractile-ring maintenance and affects the septation initiation network. Moreover, Gef2 binds to purified GTPases Rho1, Rho4, and Rho5 in vitro. Taken together, our data indicate that Nod1 and Gef2 function cooperatively in a protein complex to regulate fission yeast cytokinesis.
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Affiliation(s)
- Yi-Hua Zhu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210 Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH 43210 Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
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Jourdain I, Brzezińska EA, Toda T. Fission yeast Nod1 is a component of cortical nodes involved in cell size control and division site placement. PLoS One 2013; 8:e54142. [PMID: 23349808 PMCID: PMC3547912 DOI: 10.1371/journal.pone.0054142] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 12/05/2012] [Indexed: 11/19/2022] Open
Abstract
Most cells enter mitosis once they have reached a defined size. In the fission yeast Schizosaccharomyces pombe, mitotic entry is orchestrated by a geometry-sensing mechanism that involves the Cdk1/Cdc2-inhibiting Wee1 kinase. The factors upstream of Wee1 gather together in interphase to form a characteristic medial and cortical belt of nodes. Nodes are also considered to be precursors of the cytokinesis contractile actomyosin ring (CAR). Here we describe a new component of the interphase nodes and cytokinesis rings, which we named Nod1. Consistent with its role in cell size control at division, nod1Δ cells were elongated and epistatic with regulators of Wee1. Through biochemical and localisation studies, we placed Nod1 in a complex with the Rho-guanine nucleotide exchange factor Gef2. Nod1 and Gef2 mutually recruited each other in nodes and Nod1 also assembles Gef2 in rings. Like gef2Δ, nod1Δ cells showed a mild displacement of their division plane and this phenotype was severely exacerbated when the parallel Polo kinase pathway was also compromised. We conclude that Nod1 specifies the division site by localising Gef2 to the mitotic cell middle. Previous work showed that Gef2 in turn anchors factors that control the spatio-temporal recruitment of the actin nucleation machinery. It is believed that the actin filaments originated from the nodes pull nodes together into a single contractile ring. Surprisingly however, we found that node proteins could form pre-ring helical filaments in a cdc12-112 mutant in which nucleation of the actin ring is impaired. Furthermore, the deletion of either nod1 or gef2 created an un-expected situation where different ring components were recruited sequentially rather than simultaneously. At later stages of cytokinesis, these various rings appeared inter-fitted rather than merged. This study brings a new slant to the understanding of CAR assembly and function.
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Affiliation(s)
- Isabelle Jourdain
- Cell Regulation Laboratory, London Research Institute, Cancer Research UK, London, United Kingdom
| | - Elspeth A. Brzezińska
- Cell Regulation Laboratory, London Research Institute, Cancer Research UK, London, United Kingdom
| | - Takashi Toda
- Cell Regulation Laboratory, London Research Institute, Cancer Research UK, London, United Kingdom
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Blt1 and Mid1 provide overlapping membrane anchors to position the division plane in fission yeast. Mol Cell Biol 2012; 33:418-28. [PMID: 23149940 DOI: 10.1128/mcb.01286-12] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Spatial control of cytokinesis is essential for proper cell division. The molecular mechanisms that anchor the dynamic assembly and constriction of the cytokinetic ring at the plasma membrane remain unclear. In the fission yeast Schizosaccharomyces pombe, the cytokinetic ring is assembled in the cell middle from cortical node precursors that are positioned by the anillin-like protein Mid1. During mitotic entry, cortical nodes mature and then compact into a contractile ring positioned in the cell middle. The molecular link between Mid1 and medial cortical nodes remains poorly defined. Here we show that Blt1, a previously enigmatic cortical node protein, promotes the robust association of Mid1 with cortical nodes. Blt1 interacts with Mid1 through the RhoGEF Gef2 to stabilize nodes at the cell cortex during the early stages of contractile ring assembly. The Blt1 N terminus is required for localization and function, while the Blt1 C terminus promotes cortical localization by interacting with phospholipids. In cells lacking membrane binding by both Mid1 and Blt1, nodes detach from the cell cortex and generate aberrant cytokinetic rings. We conclude that Blt1 acts as a scaffolding protein for precursors of the cytokinetic ring and that Blt1 and Mid1 provide overlapping membrane anchors for proper division plane positioning.
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Hachet O, Bendezú FO, Martin SG. Fission yeast: in shape to divide. Curr Opin Cell Biol 2012; 24:858-64. [PMID: 23127610 DOI: 10.1016/j.ceb.2012.10.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 09/27/2012] [Accepted: 10/02/2012] [Indexed: 01/27/2023]
Abstract
How are cell morphogenesis and cell cycle coordinated? The fission yeast is a rod-shaped unicellular organism widely used to study how a cell self-organizes in space and time. Here, we discuss recent advances in understanding how the cell acquires and maintains its regular rod shape and uses it to control cell division. The cellular body plan is established by microtubules, which mark antipodal growth zones and medial division. In turn, cellular dimensions are defined by the small GTPase Cdc42 and downstream regulators of vesicle trafficking. Yeast cells then repetitively use their simple rod shape to orchestrate the position and timing of cell division.
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Affiliation(s)
- Olivier Hachet
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
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Saha S, Pollard TD. Characterization of structural and functional domains of the anillin-related protein Mid1p that contribute to cytokinesis in fission yeast. Mol Biol Cell 2012; 23:3993-4007. [PMID: 22918954 PMCID: PMC3469515 DOI: 10.1091/mbc.e12-07-0536] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Fission yeast cells depend on the anillin-related protein Mid1p for reliable cytokinesis. Insolubility limits the purification of full-length Mid1p for biophysical analysis, and lack of knowledge about the structural domains of Mid1p limits functional analysis. We addressed these limitations by identifying in a bacterial expression screen of random Mid1p fragments five soluble segments that can be purified and one insoluble segment. Using complementation experiments in Δmid1 cells, we tested the biological functions of these six putative domains that account for full-length Mid1p. The N-terminal domain (residues 1-149) is essential for correct positioning and orientation of septa. The third domain (residues 309-452) allows the construct composed of the first three domains (residues 1-452) to form hydrodynamically well-behaved octamers. Constructs consisting of residues 1-452 or 1-578 carry out most functions of full-length Mid1p, including concentration at the equatorial cortex in nodes that accumulate myosin-II and other contractile ring proteins during mitosis. However, cells depending on these constructs without the insoluble domain (residues 579-797) form equatorially located rings slowly from strands rather than by direct condensation of nodes. We conclude that residues 1-578 assemble node components myosin-II, Rng2p, and Cdc15p, and the insoluble domain facilitates the normal, efficient condensation of nodes into rings.
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Affiliation(s)
- Shambaditya Saha
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103, USA
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Lee IJ, Coffman VC, Wu JQ. Contractile-ring assembly in fission yeast cytokinesis: Recent advances and new perspectives. Cytoskeleton (Hoboken) 2012; 69:751-63. [PMID: 22887981 DOI: 10.1002/cm.21052] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 07/16/2012] [Indexed: 11/07/2022]
Abstract
The fission yeast Schizosaccharomyces pombe is an excellent model organism to study cytokinesis. Here, we review recent advances on contractile-ring assembly in fission yeast. First, we summarize the assembly of cytokinesis nodes, the precursors of a normal contractile ring. IQGAP Rng2 and myosin essential light chain Cdc4 are recruited by the anillin-like protein Mid1, followed by the addition of other cytokinesis node proteins. Mid1 localization on the plasma membrane is stabilized by interphase node proteins. Second, we discuss proteins and processes that contribute to the search, capture, pull, and release mechanism of contractile-ring assembly. Actin filaments nucleated by formin Cdc12, the motor activity of myosin-II, the stiffness of the actin network, and severing of actin filaments by cofilin all play essential roles in contractile-ring assembly. Finally, we discuss the Mid1-independent pathway for ring assembly, and the possible mechanisms underlying the ring maturation and constriction. Collectively, we provide an overview of the current understanding of contractile-ring assembly and uncover future directions in studying cytokinesis in fission yeast.
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Affiliation(s)
- I-Ju Lee
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, USA
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35
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Saha S, Pollard TD. Anillin-related protein Mid1p coordinates the assembly of the cytokinetic contractile ring in fission yeast. Mol Biol Cell 2012; 23:3982-92. [PMID: 22918943 PMCID: PMC3469514 DOI: 10.1091/mbc.e12-07-0535] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Anillin-like protein Mid1p coordinates contractile ring assembly in fission yeast by restricting precursors in nodes around the equator. Without Mid1p, contractile ring assembly is slow and unreliable because ring precursors are separated in nodes (Blt1p, Cdc12p) or strands (myosin-II, Rng2p, Cdc15p, actin filaments) scattered widely in the cortex. In fission yeast cells cortical nodes containing the protein Blt1p and several kinases appear early in G2, mature into cytokinetic nodes by adding anillin Mid1p, myosin-II, formin Cdc12p, and other proteins, and condense into a contractile ring by movements that depend on actin and myosin-II. Previous studies concluded that cells without Mid1p lack cytokinetic nodes and assemble rings unreliably from myosin-II strands but left open questions. Why do strands form outside the equatorial region? Why is ring assembly unreliable without Mid1p? We found in Δmid1 cells that Cdc12p accumulates in cytokinetic nodes scattered in the cortex and produces actin filaments that associate with myosin-II, Rng2p, and Cdc15p to form strands located between the nodes. Strands incorporate nodes, and in ∼67% of cells, strands slowly close into rings that constrict without the normal ∼25-min maturation period. Ring assembly is unreliable and slow without Mid1p because the scattered Cdc12p nodes generate strands spread widely beyond the equator, and growing strands depend on random encounters to merge with other strands into a ring. We conclude that orderly assembly of the contractile ring in wild-type cells depends on Mid1p to recruit myosin-II, Rng2p, and Cdc15p to nodes and to place cytokinetic nodes around the cell equator.
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Affiliation(s)
- Shambaditya Saha
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103, USA
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36
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Rincon SA, Paoletti A. Mid1/anillin and the spatial regulation of cytokinesis in fission yeast. Cytoskeleton (Hoboken) 2012; 69:764-77. [DOI: 10.1002/cm.21056] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 07/13/2012] [Accepted: 07/20/2012] [Indexed: 12/20/2022]
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Laporte D, Ojkic N, Vavylonis D, Wu JQ. α-Actinin and fimbrin cooperate with myosin II to organize actomyosin bundles during contractile-ring assembly. Mol Biol Cell 2012; 23:3094-110. [PMID: 22740629 PMCID: PMC3418305 DOI: 10.1091/mbc.e12-02-0123] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
During cytokinesis in Schizosaccharomyces pombe, the transient connections between nodes allow them to condense into the contractile ring. We find that α-actinin and fimbrin, two actin cross-linking proteins, are critical for node condensation as they stabilize transient linear actomyosin structures and thus modulate the morphology of the actomyosin network. The actomyosin contractile ring assembles through the condensation of a broad band of nodes that forms at the cell equator in fission yeast cytokinesis. The condensation process depends on actin filaments that interconnect nodes. By mutating or titrating actin cross-linkers α-actinin Ain1 and fimbrin Fim1 in live cells, we reveal that both proteins are involved in node condensation. Ain1 and Fim1 stabilize the actin cytoskeleton and modulate node movement, which prevents nodes and linear structures from aggregating into clumps and allows normal ring formation. Our computer simulations modeling actin filaments as semiflexible polymers reproduce the experimental observations and provide a model of how actin cross-linkers work with other proteins to regulate actin-filament orientations inside actin bundles and organize the actin network. As predicted by the simulations, doubling myosin II Myo2 level rescues the node condensation defects caused by Ain1 overexpression. Taken together, our work supports a cooperative process of ring self-organization driven by the interaction between actin filaments and myosin II, which is progressively stabilized by the cross-linking proteins.
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Affiliation(s)
- Damien Laporte
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
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Lee IJ, Wu JQ. Characterization of Mid1 domains for targeting and scaffolding in fission yeast cytokinesis. J Cell Sci 2012; 125:2973-85. [PMID: 22427686 DOI: 10.1242/jcs.102574] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Division-site selection and contractile-ring assembly are two crucial steps in cytokinesis. In fission yeast, the anillin-like Mid1 protein specifies the division site at the cell equator by assembling cortical nodes, the precursors of the contractile ring. Thus, Mid1 is essential for linking the positional cues for the cleavage site to contractile-ring formation. However, how Mid1 domains cooperate to regulate cytokinesis is poorly understood. Here we unravel the functions of different Mid1 domains (motifs) by a series of truncations. We report that the conserved PH domain stabilizes Mid1 in nodes by binding to lipids and is required for Mid1 cortical localization during interphase in the absence of Cdr2 kinase. Mid1 lacking an internal region that is approximately one third of the full-length protein has higher nuclear and cortical concentration and suppresses the division-site positioning defects in cells with a deletion of the dual-specificity tyrosine-regulated kinase Pom1. The N-terminus of Mid1 physically interacts with cytokinesis node proteins. When fused to cortical node protein Cdr2, Mid1(1-100) is sufficient to assemble cytokinesis nodes and the contractile ring. Collectively, our study recognizes domains regulating Mid1 cortical localization and reveals domains sufficient for contractile-ring assembly.
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Affiliation(s)
- I-Ju Lee
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
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