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Hill TW, Wendt KE, Jones DA, Williamson MH, Ugwu UJ, Rowland LB, Jackson-Hayes L. The Aspergillus nidulans IQGAP orthologue SepG is required for constriction of the contractile actomyosin ring. Fungal Genet Biol 2020; 144:103439. [PMID: 32768603 DOI: 10.1016/j.fgb.2020.103439] [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: 01/28/2020] [Revised: 07/14/2020] [Accepted: 07/28/2020] [Indexed: 10/23/2022]
Abstract
In this research we report that the sepG1 mutation in Aspergillus nidulans resides in gene AN9463, which is predicted to encode an IQGAP orthologue. The genetic lesion is predicted to result in a G-to-R substitution at residue 1637 of the 1737-residue protein in a highly conserved region of the RasGAP-C-terminal (RGCT) domain. When grown at restrictive temperature, strains expressing the sepGG1637R (sepG1) allele are aseptate, with reduced colony growth and aberrantly formed conidiophores. The aseptate condition can be replicated by deletion of AN9463 or by downregulating its expression via introduced promoters. The mutation does not prevent assembly of a cortical contractile actomyosin ring (CAR) at putative septation sites, but tight compaction of the rings is impaired and the rings fail to constrict. Both GFP::SepG wild type and the GFP-tagged product of the sepG1 allele localize to the CAR at both permissive and restrictive temperatures. Downregulation of myoB (encoding the A. nidulans type-II myosin heavy chain) does not prevent formation of SepG rings at septation sites, but filamentous actin is required for CAR localization of SepG and MyoB. We identify fourteen probable IQ-motifs (EF-hand protein binding sites) in the predicted SepG sequence. Two of the A. nidulans EF-hand proteins, myosin essential light chain (AnCdc4) and myosin regulatory light chain (MrlC), colocalize with SepG and MyoB at all stages of CAR formation and constriction. However, calmodulin (CamA) appears at septation sites only after the CAR has become fully compacted. When expression of sepG is downregulated, leaving MyoB as the sole IQ-motif protein in the pre-compaction CAR, both MrlC and AnCdc4 continue to associate with the forming CAR. When myoB expression is downregulated, leaving SepG as the sole IQ-motif protein in the CAR, AnCdc4 association with the forming CAR continues but MrlC fails to associate. This supports a model in which the IQ motifs of MyoB bind both MrlC and AnCdc4, while the IQ motifs of SepG bind only AnCdc4. Downregulation of either mrlC or Ancdc4 results in an aseptate phenotype, but has no effect on association of either SepG or MyoB with the CAR.
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Affiliation(s)
- Terry W Hill
- Department of Biology, Rhodes College, Memphis, TN 38112, USA; Biochemistry and Molecular Biology Program, Rhodes College, Memphis, TN 38112, USA.
| | - Kristen E Wendt
- Biochemistry and Molecular Biology Program, Rhodes College, Memphis, TN 38112, USA
| | - David A Jones
- Department of Chemistry, Rhodes College, Memphis, TN 38112, USA
| | - McLean H Williamson
- Biochemistry and Molecular Biology Program, Rhodes College, Memphis, TN 38112, USA
| | - Uchenna J Ugwu
- Division of Natural & Mathematic Sciences, LeMoyne-Owen College, Memphis, TN 38126, USA
| | - Lauren B Rowland
- Biochemistry and Molecular Biology Program, Rhodes College, Memphis, TN 38112, USA
| | - Loretta Jackson-Hayes
- Biochemistry and Molecular Biology Program, Rhodes College, Memphis, TN 38112, USA; Department of Chemistry, Rhodes College, Memphis, TN 38112, USA
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102
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Abstract
It is widely believed that cleavage-furrow formation during cytokinesis is driven by the contraction of a ring containing F-actin and type-II myosin. However, even in cells that have such rings, they are not always essential for furrow formation. Moreover, many taxonomically diverse eukaryotic cells divide by furrowing but have no type-II myosin, making it unlikely that an actomyosin ring drives furrowing. To explore this issue further, we have used one such organism, the green alga Chlamydomonas reinhardtii We found that although F-actin is associated with the furrow region, none of the three myosins (of types VIII and XI) is localized there. Moreover, when F-actin was eliminated through a combination of a mutation and a drug, furrows still formed and the cells divided, although somewhat less efficiently than normal. Unexpectedly, division of the large Chlamydomonas chloroplast was delayed in the cells lacking F-actin; as this organelle lies directly in the path of the cleavage furrow, this delay may explain, at least in part, the delay in cytokinesis itself. Earlier studies had shown an association of microtubules with the cleavage furrow, and we used a fluorescently tagged EB1 protein to show that microtubules are still associated with the furrows in the absence of F-actin, consistent with the possibility that the microtubules are important for furrow formation. We suggest that the actomyosin ring evolved as one way to improve the efficiency of a core process for furrow formation that was already present in ancestral eukaryotes.
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103
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Pimm ML, Hotaling J, Henty-Ridilla JL. Profilin choreographs actin and microtubules in cells and cancer. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2020; 355:155-204. [PMID: 32859370 PMCID: PMC7461721 DOI: 10.1016/bs.ircmb.2020.05.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Actin and microtubules play essential roles in aberrant cell processes that define and converge in cancer including: signaling, morphology, motility, and division. Actin and microtubules do not directly interact, however shared regulators coordinate these polymers. While many of the individual proteins important for regulating and choreographing actin and microtubule behaviors have been identified, the way these molecules collaborate or fail in normal or disease contexts is not fully understood. Decades of research focus on Profilin as a signaling molecule, lipid-binding protein, and canonical regulator of actin assembly. Recent reports demonstrate that Profilin also regulates microtubule dynamics and polymerization. Thus, Profilin can coordinate both actin and microtubule polymer systems. Here we reconsider the biochemical and cellular roles for Profilin with a focus on the essential cytoskeletal-based cell processes that go awry in cancer. We also explore how the use of model organisms has helped to elucidate mechanisms that underlie the regulatory essence of Profilin in vivo and in the context of disease.
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Affiliation(s)
- Morgan L Pimm
- Department of Cell and Developmental Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, NY, United States
| | - Jessica Hotaling
- Department of Cell and Developmental Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, NY, United States
| | - Jessica L Henty-Ridilla
- Department of Cell and Developmental Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, NY, United States; Department of Biochemistry and Molecular Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, NY, United States.
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104
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Bindl J, Molnar ES, Ecke M, Prassler J, Müller-Taubenberger A, Gerisch G. Unilateral Cleavage Furrows in Multinucleate Cells. Cells 2020; 9:E1493. [PMID: 32570994 PMCID: PMC7349700 DOI: 10.3390/cells9061493] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/15/2020] [Accepted: 06/16/2020] [Indexed: 12/16/2022] Open
Abstract
Multinucleate cells can be produced in Dictyostelium by electric pulse-induced fusion. In these cells, unilateral cleavage furrows are formed at spaces between areas that are controlled by aster microtubules. A peculiarity of unilateral cleavage furrows is their propensity to join laterally with other furrows into rings to form constrictions. This means cytokinesis is biphasic in multinucleate cells, the final abscission of daughter cells being independent of the initial direction of furrow progression. Myosin-II and the actin filament cross-linking protein cortexillin accumulate in unilateral furrows, as they do in the normal cleavage furrows of mononucleate cells. In a myosin-II-null background, multinucleate or mononucleate cells were produced by cultivation either in suspension or on an adhesive substrate. Myosin-II is not essential for cytokinesis either in mononucleate or in multinucleate cells but stabilizes and confines the position of the cleavage furrows. In fused wild-type cells, unilateral furrows ingress with an average velocity of 1.7 µm × min-1, with no appreciable decrease of velocity in the course of ingression. In multinucleate myosin-II-null cells, some of the furrows stop growing, thus leaving space for the extensive broadening of the few remaining furrows.
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Affiliation(s)
- Julia Bindl
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany; (J.B.); (E.S.M.); (M.E.); (J.P.)
| | - Eszter Sarolta Molnar
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany; (J.B.); (E.S.M.); (M.E.); (J.P.)
| | - Mary Ecke
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany; (J.B.); (E.S.M.); (M.E.); (J.P.)
| | - Jana Prassler
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany; (J.B.); (E.S.M.); (M.E.); (J.P.)
| | - Annette Müller-Taubenberger
- LMU Munich, Department of Cell Biology (Anatomy III), Biomedical Center, D-82152 Planegg-Martinsried, Germany;
| | - Günther Gerisch
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany; (J.B.); (E.S.M.); (M.E.); (J.P.)
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105
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Nguyen LTS, Robinson DN. The Unusual Suspects in Cytokinesis: Fitting the Pieces Together. Front Cell Dev Biol 2020; 8:441. [PMID: 32626704 PMCID: PMC7314909 DOI: 10.3389/fcell.2020.00441] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/11/2020] [Indexed: 01/24/2023] Open
Abstract
Cytokinesis is the step of the cell cycle in which the cell must faithfully separate the chromosomes and cytoplasm, yielding two daughter cells. The assembly and contraction of the contractile network is spatially and temporally coupled with the formation of the mitotic spindle to ensure the successful completion of cytokinesis. While decades of studies have elucidated the components of this machinery, the so-called usual suspects, and their functions, many lines of evidence are pointing to other unexpected proteins and sub-cellular systems as also being involved in cytokinesis. These we term the unusual suspects. In this review, we introduce recent discoveries on some of these new unusual suspects and begin to consider how these subcellular systems snap together to help complete the puzzle of cytokinesis.
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Affiliation(s)
- Ly T. S. Nguyen
- Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Douglas N. Robinson
- Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, MD, United States
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, MD, United States
- Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD, United States
- Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD, United States
- Chemical and Biomolecular Engineering, Johns Hopkins University Whiting School of Engineering, Baltimore, MD, United States
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106
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Bell KR, Werner ME, Doshi A, Cortes DB, Sattler A, Vuong-Brender T, Labouesse M, Maddox AS. Novel cytokinetic ring components drive negative feedback in cortical contractility. Mol Biol Cell 2020; 31:1623-1636. [PMID: 32491957 PMCID: PMC7521795 DOI: 10.1091/mbc.e20-05-0304] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Actomyosin cortical contractility drives many cell shape changes including cytokinetic furrowing. While positive regulation of contractility is well characterized, counterbalancing negative regulation and mechanical brakes are less well understood. The small GTPase RhoA is a central regulator, activating cortical actomyosin contractility during cytokinesis and other events. Here we report how two novel cytokinetic ring components, GCK-1 (germinal center kinase-1) and CCM-3 (cerebral cavernous malformations-3), participate in a negative feedback loop among RhoA and its cytoskeletal effectors to inhibit contractility. GCK-1 and CCM-3 are recruited by active RhoA and anillin to the cytokinetic ring, where they in turn limit RhoA activity and contractility. This is evidenced by increased RhoA activity, anillin and nonmuscle myosin II in the cytokinetic ring, and faster cytokinetic furrowing, following depletion of GCK-1 or CCM-3. GCK-1 or CCM-3 depletion also reduced RGA-3 levels in pulses and increased baseline RhoA activity and pulsed contractility during zygote polarization. Together, our results suggest that GCK-1 and CCM-3 regulate cortical actomyosin contractility via negative feedback. These findings have implications for the molecular and cellular mechanisms of cerebral cavernous malformation pathologies.
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Affiliation(s)
- Kathryn Rehain Bell
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Michael E Werner
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Anusha Doshi
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Daniel B Cortes
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Adam Sattler
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Thanh Vuong-Brender
- Institut de Biologie Paris-Seine, Sorbonne Université, INSERM, 75005 Paris, France
| | - Michel Labouesse
- Institut de Biologie Paris-Seine, Sorbonne Université, INSERM, 75005 Paris, France
| | - Amy Shaub Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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107
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Ma J, Liu X, Liu P, Lu W, Shen X, Ma R, Zong H. Identification of a new p53 responsive element in the promoter region of anillin. Int J Mol Med 2020; 45:1563-1570. [PMID: 32323752 DOI: 10.3892/ijmm.2020.4527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 12/06/2019] [Indexed: 11/06/2022] Open
Abstract
The expression of anillin mRNA and protein is regulated in a cell cycle‑dependent manner. However, the mechanism underlying this process is unclear. Previous studies analyzing the sequence of the 5'‑untranslated region of anillin have unveiled several putative p53 binding sites. Therefore, the present study hypothesized that the anillin gene may be repressed by p53 and that the commonly observed mutation (or loss of function) of p53 may serve a role in this phenotype. Bioinformatic analysis of the anillin promoter region revealed potential p53 responsive elements. Of those identified, 2 were able to bind p53 protein, as determined via a chromatin immunoprecipitation assay. Although it was hypothesized that DNA damage and resultant p53 expression would repress anillin expression, the results revealed that anillin mRNA and protein expression levels were negatively regulated by DNA damage in the wild‑type p53 cells, but not in the isogenic p53 null cells. Furthermore, DNA sequences encompassing the p53 binding site downregulated luciferase transgenes in a p53 dependent manner. Taken together, these data indicated that anillin was negatively regulated by p53 and that anillin overexpression observed in cancer may be a p53‑mediated phenomenon. The data from the present study provided further evidence for the role of p53 in the biologically crucial process of cytokinesis.
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Affiliation(s)
- Jiao Ma
- Department of Biochemistry and Molecular Cell Biology, Shanghai Jiaotong University Medical School, Shanghai 200025, P.R. China
| | - Xinying Liu
- Department of Biochemistry and Molecular Cell Biology, Shanghai Jiaotong University Medical School, Shanghai 200025, P.R. China
| | - Pengyi Liu
- Department of Biochemistry and Molecular Cell Biology, Shanghai Jiaotong University Medical School, Shanghai 200025, P.R. China
| | - Wenqing Lu
- Department of Biochemistry and Molecular Cell Biology, Shanghai Jiaotong University Medical School, Shanghai 200025, P.R. China
| | - Xinxin Shen
- Department of Biochemistry and Molecular Cell Biology, Shanghai Jiaotong University Medical School, Shanghai 200025, P.R. China
| | - Ruixiang Ma
- Department of Biochemistry and Molecular Cell Biology, Shanghai Jiaotong University Medical School, Shanghai 200025, P.R. China
| | - Hongliang Zong
- Shanghai PerHum Therapeutics Co. Ltd., Shanghai 200052, P.R. China
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108
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Beaudet D, Pham N, Skaik N, Piekny A. Importin binding mediates the intramolecular regulation of anillin during cytokinesis. Mol Biol Cell 2020; 31:1124-1139. [PMID: 32238082 PMCID: PMC7353161 DOI: 10.1091/mbc.e20-01-0006] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cytokinesis occurs by the ingression of an actomyosin ring that cleaves a cell into two daughters. This process is tightly controlled to avoid aneuploidy, and we previously showed that active Ran coordinates ring positioning with chromatin. Active Ran is high around chromatin, and forms an inverse gradient to cargo-bound importins. We found that the ring component anillin contains a nuclear localization signal (NLS) that binds to importin and is required for its function during cytokinesis. Here we reveal the mechanism whereby importin binding favors a conformation required for anillin's recruitment to the equatorial cortex. Active RhoA binds to the RhoA-binding domain causing an increase in accessibility of the nearby C2 domain containing the NLS. Importin binding subsequently stabilizes a conformation that favors interactions for cortical recruitment. In addition to revealing a novel mechanism for the importin-mediated regulation of a cortical protein, we also show how importin binding positively regulates protein function.
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Affiliation(s)
- Daniel Beaudet
- Department of Bioengineering, McGill University, Montreal, QC, Canada, H3A 0G4
| | - Nhat Pham
- Department of Biology, Concordia University, Montreal, QC, Canada, H4B 1R6
| | - Noha Skaik
- Department of Biology, Concordia University, Montreal, QC, Canada, H4B 1R6
| | - Alisa Piekny
- Department of Biology, Concordia University, Montreal, QC, Canada, H4B 1R6
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109
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Meaders JL, Burgess DR. Microtubule-Based Mechanisms of Pronuclear Positioning. Cells 2020; 9:E505. [PMID: 32102180 PMCID: PMC7072840 DOI: 10.3390/cells9020505] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 12/22/2022] Open
Abstract
The zygote is defined as a diploid cell resulting from the fusion of two haploid gametes. Union of haploid male and female pronuclei in many animals occurs through rearrangements of the microtubule cytoskeleton into a radial array of microtubules known as the sperm aster. The sperm aster nucleates from paternally-derived centrioles attached to the male pronucleus after fertilization. Nematode, echinoderm, and amphibian eggs have proven as invaluable models to investigate the biophysical principles for how the sperm aster unites male and female pronuclei with precise spatial and temporal regulation. In this review, we compare these model organisms, discussing the dynamics of sperm aster formation and the different force generating mechanism for sperm aster and pronuclear migration. Finally, we provide new mechanistic insights for how sperm aster growth may influence sperm aster positioning.
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Affiliation(s)
| | - David R Burgess
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA
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110
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Abstract
The Ran pathway has a well-described function in nucleocytoplasmic transport, where active Ran dissociates importin/karyopherin-bound cargo containing a nuclear localization signal (NLS) in the nucleus. As cells enter mitosis, the nuclear envelope breaks down and a gradient of active Ran forms where levels are highest near chromatin. This gradient plays a crucial role in regulating mitotic spindle assembly, where active Ran binds to and releases importins from NLS-containing spindle assembly factors. An emerging theme is that the Ran gradient also regulates the actomyosin cortex for processes including polar body extrusion during meiosis, and cytokinesis. For these events, active Ran could play an inhibitory role, where importin-binding may help promote or stabilize a conformation or interaction that favours the recruitment and function of cortical regulators. For either spindle assembly or cortical polarity, the gradient of active Ran determines the extent of importin-binding, the effects of which could vary for different proteins.
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Affiliation(s)
- Imge Ozugergin
- Department of Biology, Concordia University, Montreal, QC, Canada
| | - Alisa Piekny
- Department of Biology, Concordia University, Montreal, QC, Canada
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111
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Pollard TD. Myosins in Cytokinesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1239:233-244. [DOI: 10.1007/978-3-030-38062-5_11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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112
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Structure and regulation of human epithelial cell transforming 2 protein. Proc Natl Acad Sci U S A 2019; 117:1027-1035. [PMID: 31888991 DOI: 10.1073/pnas.1913054117] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Epithelial cell transforming 2 (Ect2) protein activates Rho GTPases and controls cytokinesis and many other cellular processes. Dysregulation of Ect2 is associated with various cancers. Here, we report the crystal structure of human Ect2 and complementary mechanistic analyses. The data show the C-terminal PH domain of Ect2 folds back and blocks the canonical RhoA-binding site at the catalytic center of the DH domain, providing a mechanism of Ect2 autoinhibition. Ect2 is activated by binding of GTP-bound RhoA to the PH domain, which suggests an allosteric mechanism of Ect2 activation and a positive-feedback loop reinforcing RhoA signaling. This bimodal RhoA binding of Ect2 is unusual and was confirmed with Förster resonance energy transfer (FRET) and hydrogen-deuterium exchange mass spectrometry (HDX-MS) analyses. Several recurrent cancer-associated mutations map to the catalytic and regulatory interfaces, and dysregulate Ect2 in vitro and in vivo. Together, our findings provide mechanistic insights into Ect2 regulation in normal cells and under disease conditions.
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113
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Hammarton TC. Who Needs a Contractile Actomyosin Ring? The Plethora of Alternative Ways to Divide a Protozoan Parasite. Front Cell Infect Microbiol 2019; 9:397. [PMID: 31824870 PMCID: PMC6881465 DOI: 10.3389/fcimb.2019.00397] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 11/06/2019] [Indexed: 01/21/2023] Open
Abstract
Cytokinesis, or the division of the cytoplasm, following the end of mitosis or meiosis, is accomplished in animal cells, fungi, and amoebae, by the constriction of an actomyosin contractile ring, comprising filamentous actin, myosin II, and associated proteins. However, despite this being the best-studied mode of cytokinesis, it is restricted to the Opisthokonta and Amoebozoa, since members of other evolutionary supergroups lack myosin II and must, therefore, employ different mechanisms. In particular, parasitic protozoa, many of which cause significant morbidity and mortality in humans and animals as well as considerable economic losses, employ a wide diversity of mechanisms to divide, few, if any, of which involve myosin II. In some cases, cell division is not only myosin II-independent, but actin-independent too. Mechanisms employed range from primitive mechanical cell rupture (cytofission), to motility- and/or microtubule remodeling-dependent mechanisms, to budding involving the constriction of divergent contractile rings, to hijacking host cell division machinery, with some species able to utilize multiple mechanisms. Here, I review current knowledge of cytokinesis mechanisms and their molecular control in mammalian-infective parasitic protozoa from the Excavata, Alveolata, and Amoebozoa supergroups, highlighting their often-underappreciated diversity and complexity. Billions of people and animals across the world are at risk from these pathogens, for which vaccines and/or optimal treatments are often not available. Exploiting the divergent cell division machinery in these parasites may provide new avenues for the treatment of protozoal disease.
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Affiliation(s)
- Tansy C Hammarton
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
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114
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Papini D, Fant X, Ogawa H, Desban N, Samejima K, Feizbakhsh O, Askin B, Ly T, Earnshaw WC, Ruchaud S. Cell cycle-independent furrowing triggered by phosphomimetic mutations of the INCENP STD motif requires Plk1. J Cell Sci 2019; 132:jcs234401. [PMID: 31601613 PMCID: PMC7115952 DOI: 10.1242/jcs.234401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 09/27/2019] [Indexed: 11/20/2022] Open
Abstract
Timely and precise control of Aurora B kinase, the chromosomal passenger complex (CPC) catalytic subunit, is essential for accurate chromosome segregation and cytokinesis. Post-translational modifications of CPC subunits are directly involved in controlling Aurora B activity. Here, we identified a highly conserved acidic STD-rich motif of INCENP that is phosphorylated during mitosis in vivo and by Plk1 in vitro and is involved in controlling Aurora B activity. By using an INCENP conditional-knockout cell line, we show that impairing the phosphorylation status of this region disrupts chromosome congression and induces cytokinesis failure. In contrast, mimicking constitutive phosphorylation not only rescues cytokinesis but also induces ectopic furrows and contractile ring formation in a Plk1- and ROCK1-dependent manner independent of cell cycle and microtubule status. Our experiments identify the phospho-regulation of the INCENP STD motif as a novel mechanism that is key for chromosome alignment and cytokinesis.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Diana Papini
- Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Xavier Fant
- Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
- Sorbonne Université/CNRS UMR8227, Station Biologique, Place Georges Teissier, CS90074, 29688 ROSCOFF cedex, France
| | - Hiromi Ogawa
- Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Nathalie Desban
- Sorbonne Université/CNRS UMR8227, Station Biologique, Place Georges Teissier, CS90074, 29688 ROSCOFF cedex, France
| | - Kumiko Samejima
- Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Omid Feizbakhsh
- Sorbonne Université/CNRS UMR8227, Station Biologique, Place Georges Teissier, CS90074, 29688 ROSCOFF cedex, France
| | - Bilge Askin
- Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Tony Ly
- Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - William C. Earnshaw
- Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Sandrine Ruchaud
- Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
- Sorbonne Université/CNRS UMR8227, Station Biologique, Place Georges Teissier, CS90074, 29688 ROSCOFF cedex, France
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115
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Hamao K, Ono T, Matsushita M, Hosoya H. ZIP kinase phosphorylated and activated by Rho kinase/ROCK contributes to cytokinesis in mammalian cultured cells. Exp Cell Res 2019; 386:111707. [PMID: 31693874 DOI: 10.1016/j.yexcr.2019.111707] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/28/2019] [Accepted: 10/30/2019] [Indexed: 11/29/2022]
Abstract
Cytokinesis of animal cells requires contraction of a contractile ring, composed of actin filaments and myosin II filaments. Phosphorylation of myosin II regulatory light chain (MRLC) promotes contraction of the actomyosin ring by activating myosin II motor activity. Both Rho-associated coiled-coil kinase (Rho kinase/ROCK) and Zipper-interacting protein kinase (ZIP kinase/ZIPK) have been reported to phosphorylate MRLC at the contractile ring. However, it remains unclear whether these kinases function independently of each other. Here, we clarified that ROCK colocalizes and forms a complex with ZIPK at telophase. As ROCK is reported to phosphorylate and activate ZIPK in vitro, we hypothesized that ZIPK phosphorylated by ROCK contributes to control cytokinesis. To address this, we expressed EGFP-ZIPK wild type (WT), a non-phosphorylatable mutant (T265A) or a phosphorylation-mimicking mutant (T265D) in HeLa cells and treated these cells with a ROCK inhibitor. Decrease in phosphorylated MRLC and a delay of furrow ingression by the ROCK inhibitor were rescued by the expression of EGFP-ZIPK-T265D, but not EGFP-ZIPK-WT or -T265A. This suggests that ROCK regulates MRLC phosphorylation followed by furrow ingression, through ZIPK phosphorylation.
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Affiliation(s)
- Kozue Hamao
- Program of Basic Biology, Graduate School of Integrated Science for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526, Japan; Program of Biomedical Science, Graduate School of Integrated Science for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526, Japan; Department of Biological Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Hiratsuka, Hiroshima, 739-8526, Japan.
| | - Taichiro Ono
- Department of Biological Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Hiratsuka, Hiroshima, 739-8526, Japan
| | - Masaya Matsushita
- Department of Biological Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Hiratsuka, Hiroshima, 739-8526, Japan
| | - Hiroshi Hosoya
- Department of Biological Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Hiratsuka, Hiroshima, 739-8526, Japan
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116
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Alonso-Matilla R, Thiyagarajan S, O'Shaughnessy B. Sliding filament and fixed filament mechanisms contribute to ring tension in the cytokinetic contractile ring. Cytoskeleton (Hoboken) 2019; 76:611-625. [PMID: 31443136 DOI: 10.1002/cm.21558] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/06/2019] [Accepted: 08/14/2019] [Indexed: 11/11/2022]
Abstract
A fundamental challenge in cell biology is to understand how cells generate actomyosin-based contractile force. Here we study the actomyosin contractile ring that divides cells during cytokinesis and generates tension by a mechanism that remains poorly understood. Long ago a muscle-like sliding filament mechanism was proposed, but evidence for sarcomeric organization in contractile rings is lacking. We develop a coarse-grained model of the fission yeast cytokinetic ring, incorporating the two myosin-II isoforms Myo2 and Myp2 and severely constrained by experimental data. The model predicts that ring tension is indeed generated by a sliding filament mechanism, but a spatially and temporally homogeneous version of that in muscle. In this mechanism all pairs of oppositely oriented actin filaments are rendered tense as they are pulled toward one another and slide through clusters of myosin-II. The mechanism relies on anchoring of actin filament barbed ends to the plasma membrane, which resists lateral motion and enables filaments to become tense when pulled by myosin-II. A second fixed filament component is independent of lateral anchoring, generated by chains of like-oriented actin filaments. Myo2 contributes to both components, while Myp2 contributes to the sliding filament component only. In the face of instabilities inherent to actomyosin contractility, organizational homeostasis is maintained by rapid turnover of Myo2 and Myp2, and by drag forces that resist lateral motion of actin, Myo2 and Myp2. Thus, sliding and fixed filament mechanisms contribute to tension in the disordered contractile ring without the need for the sarcomeric architecture of muscle.
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Affiliation(s)
| | | | - Ben O'Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, New York
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117
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Verma V, Mogilner A, Maresca TJ. Classical and Emerging Regulatory Mechanisms of Cytokinesis in Animal Cells. BIOLOGY 2019; 8:biology8030055. [PMID: 31357447 PMCID: PMC6784142 DOI: 10.3390/biology8030055] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/05/2019] [Accepted: 07/23/2019] [Indexed: 12/12/2022]
Abstract
The primary goal of cytokinesis is to produce two daughter cells, each having a full set of chromosomes. To achieve this, cells assemble a dynamic structure between segregated sister chromatids called the contractile ring, which is made up of filamentous actin, myosin-II, and other regulatory proteins. Constriction of the actomyosin ring generates a cleavage furrow that divides the cytoplasm to produce two daughter cells. Decades of research have identified key regulators and underlying molecular mechanisms; however, many fundamental questions remain unanswered and are still being actively investigated. This review summarizes the key findings, computational modeling, and recent advances in understanding of the molecular mechanisms that control the formation of the cleavage furrow and cytokinesis.
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Affiliation(s)
- Vikash Verma
- Biology Department, University of Massachusetts, Amherst, MA 01003, USA.
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
- Department of Biology, New York University, New York, NY 10012, USA
| | - Thomas J Maresca
- Biology Department, University of Massachusetts, Amherst, MA 01003, USA
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, USA
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118
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Wang S, O’Shaughnessy B. Anchoring of actin to the plasma membrane enables tension production in the fission yeast cytokinetic ring. Mol Biol Cell 2019; 30:2053-2064. [PMID: 31216223 PMCID: PMC6727776 DOI: 10.1091/mbc.e19-03-0173] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/31/2019] [Accepted: 05/31/2019] [Indexed: 11/11/2022] Open
Abstract
The cytokinetic ring generates tensile force that drives cell division, but how tension emerges from the relatively disordered ring organization remains unclear. Long ago, a musclelike sliding filament mechanism was proposed, but evidence for sarcomeric order is lacking. Here we present quantitative evidence that in fission yeast, ring tension originates from barbed-end anchoring of actin filaments to the plasma membrane, providing resistance to myosin forces that enables filaments to develop tension. The role of anchoring was highlighted by experiments on isolated fission yeast rings, where sections of ring became unanchored from the membrane and shortened ∼30-fold faster than normal. The dramatically elevated constriction rates are unexplained. Here we present a molecularly explicit simulation of constricting partially anchored rings as studied in these experiments. Simulations accurately reproduced the experimental constriction rates and showed that following anchor release, a segment becomes tensionless and shortens via a novel noncontractile reeling-in mechanism at about the velocity of load-free myosin II. The ends are reeled in by barbed end-anchored actin filaments in adjacent segments. Other actin anchoring schemes failed to constrict rings. Our results quantitatively support a specific organization and anchoring scheme that generate tension in the cytokinetic ring.
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Affiliation(s)
- Shuyuan Wang
- Department of Physics, Columbia University, New York, NY 10027
| | - Ben O’Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, NY 10027
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119
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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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