51
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The Cytoskeleton-A Complex Interacting Meshwork. Cells 2019; 8:cells8040362. [PMID: 31003495 PMCID: PMC6523135 DOI: 10.3390/cells8040362] [Citation(s) in RCA: 181] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 12/22/2022] Open
Abstract
The cytoskeleton of animal cells is one of the most complicated and functionally versatile structures, involved in processes such as endocytosis, cell division, intra-cellular transport, motility, force transmission, reaction to external forces, adhesion and preservation, and adaptation of cell shape. These functions are mediated by three classical cytoskeletal filament types, as follows: Actin, microtubules, and intermediate filaments. The named filaments form a network that is highly structured and dynamic, responding to external and internal cues with a quick reorganization that is orchestrated on the time scale of minutes and has to be tightly regulated. Especially in brain tumors, the cytoskeleton plays an important role in spreading and migration of tumor cells. As the cytoskeletal organization and regulation is complex and many-faceted, this review aims to summarize the findings about cytoskeletal filament types, including substructures formed by them, such as lamellipodia, stress fibers, and interactions between intermediate filaments, microtubules and actin. Additionally, crucial regulatory aspects of the cytoskeletal filaments and the formed substructures are discussed and integrated into the concepts of cell motility. Even though little is known about the impact of cytoskeletal alterations on the progress of glioma, a final point discussed will be the impact of established cytoskeletal alterations in the cellular behavior and invasion of glioma.
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52
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Chakraborty M, Tarasovetc EV, Zaytsev AV, Godzi M, Figueiredo AC, Ataullakhanov FI, Grishchuk EL. Microtubule end conversion mediated by motors and diffusing proteins with no intrinsic microtubule end-binding activity. Nat Commun 2019; 10:1673. [PMID: 30975984 PMCID: PMC6459870 DOI: 10.1038/s41467-019-09411-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 02/28/2019] [Indexed: 01/31/2023] Open
Abstract
Accurate chromosome segregation relies on microtubule end conversion, the ill-understood ability of kinetochores to transit from lateral microtubule attachment to durable association with dynamic microtubule plus-ends. The molecular requirements for this conversion and the underlying biophysical mechanisms are elusive. We reconstituted end conversion in vitro using two kinetochore components: the plus end-directed kinesin CENP-E and microtubule-binding Ndc80 complex, combined on the surface of a microbead. The primary role of CENP-E is to ensure close proximity between Ndc80 complexes and the microtubule plus-end, whereas Ndc80 complexes provide lasting microtubule association by diffusing on the microtubule wall near its tip. Together, these proteins mediate robust plus-end coupling during several rounds of microtubule dynamics, in the absence of any specialized tip-binding or regulatory proteins. Using a Brownian dynamics model, we show that end conversion is an emergent property of multimolecular ensembles of microtubule wall-binding proteins with finely tuned force-dependent motility characteristics.
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Affiliation(s)
- Manas Chakraborty
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Centre for Mechanochemical Cell Biology, Warwick Medical School, Coventry, CV4 7AL, UK
| | - Ekaterina V Tarasovetc
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Anatoly V Zaytsev
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Maxim Godzi
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, 119991, Moscow, Russia
| | - Ana C Figueiredo
- Chromosome Instability & Dynamics Laboratory, Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde - i3S, Universidade do Porto, Rua Alfredo Allen 208, 4200-135, Porto, Portugal
| | - Fazly I Ataullakhanov
- Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, 119991, Moscow, Russia.,Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, 117997, Russia.,Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Ekaterina L Grishchuk
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA. .,Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, 117997, Russia.
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53
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Fees CP, Moore JK. A unified model for microtubule rescue. Mol Biol Cell 2019; 30:753-765. [PMID: 30672721 PMCID: PMC6589779 DOI: 10.1091/mbc.e18-08-0541] [Citation(s) in RCA: 10] [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: 08/30/2018] [Revised: 12/06/2018] [Accepted: 01/17/2019] [Indexed: 11/23/2022] Open
Abstract
How microtubules transition from depolymerization to polymerization, known as rescue, is poorly understood. Here we examine two models for rescue: 1) an "end-driven" model in which the depolymerizing end stochastically switches to a stable state; and 2) a "lattice-driven" model in which rescue sites are integrated into the microtubule before depolymerization. We test these models using a combination of computational simulations and in vitro experiments with purified tubulin. Our findings support the "lattice-driven" model by identifying repeated rescue sites in microtubules. In addition, we discover an important role for divalent cations in determining the frequency and location of rescue sites. We use "wash-in" experiments to show that divalent cations inhibit rescue during depolymerization, but not during polymerization. We propose a unified model in which rescues are driven by embedded rescue sites in microtubules, but the activity of these sites is influenced by changes in the depolymerizing ends.
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Affiliation(s)
- Colby P. Fees
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| | - Jeffrey K. Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
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54
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Spastin is a dual-function enzyme that severs microtubules and promotes their regrowth to increase the number and mass of microtubules. Proc Natl Acad Sci U S A 2019; 116:5533-5541. [PMID: 30837315 PMCID: PMC6431158 DOI: 10.1073/pnas.1818824116] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The remodeling of the microtubule cytoskeleton underlies dynamic cellular processes, such as mitosis, ciliogenesis, and neuronal morphogenesis. An important class of microtubule remodelers comprises the severases-spastin, katanin, and fidgetin-which cut microtubules into shorter fragments. While severing activity might be expected to break down the microtubule cytoskeleton, inhibiting these enzymes in vivo actually decreases, rather increases, the number of microtubules, suggesting that severases have a nucleation-like activity. To resolve this paradox, we reconstituted Drosophila spastin in a dynamic microtubule assay and discovered that it is a dual-function enzyme. In addition to its ATP-dependent severing activity, spastin is an ATP-independent regulator of microtubule dynamics that slows shrinkage and increases rescue. We observed that spastin accumulates at shrinking ends; this increase in spastin concentration may underlie the increase in rescue frequency and the slowdown in shortening. The changes in microtubule dynamics promote microtubule regrowth so that severed microtubule fragments grow, leading to an increase in the number and mass of microtubules. A mathematical model shows that spastin's effect on microtubule dynamics is essential for this nucleation-like activity: spastin switches microtubules into a state where the net flux of tubulin onto each polymer is positive, leading to the observed exponential increase in microtubule mass. This increase in the microtubule mass accounts for spastin's in vivo phenotypes.
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55
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Song K, Gras C, Capin G, Gimber N, Lehmann M, Mohd S, Puchkov D, Rödiger M, Wilhelmi I, Daumke O, Schmoranzer J, Schürmann A, Krauss M. A SEPT1-based scaffold is required for Golgi integrity and function. J Cell Sci 2019; 132:132/3/jcs225557. [PMID: 30709970 PMCID: PMC6382012 DOI: 10.1242/jcs.225557] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/17/2018] [Indexed: 12/13/2022] Open
Abstract
Compartmentalization of membrane transport and signaling processes is of pivotal importance to eukaryotic cell function. While plasma membrane compartmentalization and dynamics are well known to depend on the scaffolding function of septin GTPases, the roles of septins at intracellular membranes have remained largely elusive. Here, we show that the structural and functional integrity of the Golgi depends on its association with a septin 1 (SEPT1)-based scaffold, which promotes local microtubule nucleation and positioning of the Golgi. SEPT1 function depends on the Golgi matrix protein GM130 (also known as GOLGA2) and on centrosomal proteins, including CEP170 and components of γ-tubulin ring complex (γ-Turc), to facilitate the perinuclear concentration of Golgi membranes. Accordingly, SEPT1 depletion triggers a massive fragmentation of the Golgi ribbon, thereby compromising anterograde membrane traffic at the level of the Golgi.
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Affiliation(s)
- Kyungyeun Song
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) Berlin, Molecular Pharmacology and Cell Biology, 13125 Berlin, Germany
| | - Claudia Gras
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) Berlin, Molecular Pharmacology and Cell Biology, 13125 Berlin, Germany
| | - Gabrielle Capin
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) Berlin, Molecular Pharmacology and Cell Biology, 13125 Berlin, Germany
| | - Niclas Gimber
- Charité Universitätsmedizin Berlin, Advanced Medical Bioimaging Core Facility - AMBIO, 10117 Berlin, Germany
| | - Martin Lehmann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) Berlin, Cellular Imaging Facility, 13125 Berlin, Germany
| | - Saif Mohd
- Max-Delmbrück-Centrum für Molekulare Medizin, 13125 Berlin, Germany
| | - Dmytro Puchkov
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) Berlin, Cellular Imaging Facility, 13125 Berlin, Germany
| | - Maria Rödiger
- Deutsches Institut für Ernährungsforschung, Potsdam Rehbrücke, and German Center for Diabetes Research (DZD), München-Neuherberg, 14558 Potsdam-Rehbrücke, Germany
| | - Ilka Wilhelmi
- Deutsches Institut für Ernährungsforschung, Potsdam Rehbrücke, and German Center for Diabetes Research (DZD), München-Neuherberg, 14558 Potsdam-Rehbrücke, Germany
| | - Oliver Daumke
- Max-Delmbrück-Centrum für Molekulare Medizin, 13125 Berlin, Germany
| | - Jan Schmoranzer
- Charité Universitätsmedizin Berlin, Advanced Medical Bioimaging Core Facility - AMBIO, 10117 Berlin, Germany
| | - Annette Schürmann
- Deutsches Institut für Ernährungsforschung, Potsdam Rehbrücke, and German Center for Diabetes Research (DZD), München-Neuherberg, 14558 Potsdam-Rehbrücke, Germany
| | - Michael Krauss
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) Berlin, Molecular Pharmacology and Cell Biology, 13125 Berlin, Germany
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56
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Lawrence EJ, Zanic M. Rescuing microtubules from the brink of catastrophe: CLASPs lead the way. Curr Opin Cell Biol 2019; 56:94-101. [PMID: 30453184 PMCID: PMC6370552 DOI: 10.1016/j.ceb.2018.10.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 10/12/2018] [Accepted: 10/31/2018] [Indexed: 01/11/2023]
Abstract
Microtubules are cytoskeletal polymers that dynamically remodel to perform essential cellular functions. Individual microtubules alternate between phases of growth and shrinkage via sudden transitions called catastrophe and rescue, driven by losing and regaining a stabilizing cap at the dynamic microtubule end. New in vitro studies now show that a conserved family of CLASP proteins specifically modulate microtubule catastrophe and rescue transitions. Further, recent cryo-electron microscopy approaches have elucidated new structural features of the stabilizing cap. Together, these new advances provide a clearer view on the complexity of the microtubule end and its regulation.
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Affiliation(s)
- E J Lawrence
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, United States
| | - M Zanic
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, United States; Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37240, United States; Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, United States.
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57
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Lindeboom JJ, Nakamura M, Saltini M, Hibbel A, Walia A, Ketelaar T, Emons AMC, Sedbrook JC, Kirik V, Mulder BM, Ehrhardt DW. CLASP stabilization of plus ends created by severing promotes microtubule creation and reorientation. J Cell Biol 2019; 218:190-205. [PMID: 30377221 PMCID: PMC6314540 DOI: 10.1083/jcb.201805047] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 09/04/2018] [Accepted: 10/17/2018] [Indexed: 12/23/2022] Open
Abstract
Central to the building and reorganizing cytoskeletal arrays is creation of new polymers. Although nucleation has been the major focus of study for microtubule generation, severing has been proposed as an alternative mechanism to create new polymers, a mechanism recently shown to drive the reorientation of cortical arrays of higher plants in response to blue light perception. Severing produces new plus ends behind the stabilizing GTP-cap. An important and unanswered question is how these ends are stabilized in vivo to promote net microtubule generation. Here we identify the conserved protein CLASP as a potent stabilizer of new plus ends created by katanin severing in plant cells. Clasp mutants are defective in cortical array reorientation. In these mutants, both rescue of shrinking plus ends and the stabilization of plus ends immediately after severing are reduced. Computational modeling reveals that it is the specific stabilization of severed ends that best explains CLASP's function in promoting microtubule amplification by severing and array reorientation.
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Affiliation(s)
- Jelmer J Lindeboom
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA
- Laboratory of Cell Biology, Wageningen University, Wageningen, Netherlands
| | - Masayoshi Nakamura
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA
- Institute of Transformative Bio-Molecules, Nagoya University, Nagoya, Japan
| | | | - Anneke Hibbel
- Laboratory of Cell Biology, Wageningen University, Wageningen, Netherlands
| | - Ankit Walia
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA
- Sainsbury Laboratory, University of Cambridge, Cambridge, UK
| | - Tijs Ketelaar
- Laboratory of Cell Biology, Wageningen University, Wageningen, Netherlands
| | - Anne Mie C Emons
- Laboratory of Cell Biology, Wageningen University, Wageningen, Netherlands
- Institute AMOLF, Amsterdam, Netherlands
| | - John C Sedbrook
- School of Biological Sciences, Illinois State University, Normal, IL
| | - Viktor Kirik
- School of Biological Sciences, Illinois State University, Normal, IL
| | - Bela M Mulder
- Laboratory of Cell Biology, Wageningen University, Wageningen, Netherlands
- Institute AMOLF, Amsterdam, Netherlands
| | - David W Ehrhardt
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA
- Department of Biology, Stanford University, Stanford, CA
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58
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Abstract
Neurons are polarized cells with long branched axons and dendrites. Microtubule generation and organization machineries are crucial to grow and pattern these complex cellular extensions. Microtubule organizing centers (MTOCs) concentrate the molecular machinery for templating microtubules, stabilizing the nascent polymer, and organizing the resultant microtubules into higher-order structures. MTOC formation and function are well described at the centrosome, in the spindle, and at interphase Golgi; we review these studies and then describe recent results about how the machineries acting at these classic MTOCs are repurposed in the postmitotic neuron for axon and dendrite differentiation. We further discuss a constant tug-of-war interplay between different MTOC activities in the cell and how this process can be used as a substrate for transcription factor-mediated diversification of neuron types.
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Affiliation(s)
- Jason Y Tann
- Laboratory for Neurodiversity, RIKEN Centre for Brain Science, Saitama, Japan
| | - Adrian W Moore
- Laboratory for Neurodiversity, RIKEN Centre for Brain Science, Saitama, Japan.
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59
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Edzuka T, Goshima G. Drosophila kinesin-8 stabilizes the kinetochore-microtubule interaction. J Cell Biol 2018; 218:474-488. [PMID: 30538142 PMCID: PMC6363442 DOI: 10.1083/jcb.201807077] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 10/24/2018] [Accepted: 11/28/2018] [Indexed: 02/06/2023] Open
Abstract
Kinesin-8 motor proteins control chromosome alignment in a variety of species, but the specific biochemical activity responsible is unclear. Edzuka and Goshima find that Drosophila kinesin-8 (Klp67A) exhibits both microtubule plus end–stabilizing and –destabilizing activities in vitro. In cells, Klp67A, and likely human kinesin-8 (KIF18A) as well, stabilize the kinetochore–microtubule attachment during mitosis. Kinesin-8 is required for proper chromosome alignment in a variety of animal and yeast cell types. However, it is unclear how this motor protein family controls chromosome alignment, as multiple biochemical activities, including inconsistent ones between studies, have been identified. Here, we find that Drosophila kinesin-8 (Klp67A) possesses both microtubule (MT) plus end–stabilizing and –destabilizing activity, in addition to kinesin-8's commonly observed MT plus end–directed motility and tubulin-binding activity in vitro. We further show that Klp67A is required for stable kinetochore–MT attachment during prometaphase in S2 cells. In the absence of Klp67A, abnormally long MTs interact in an “end-on” fashion with kinetochores at normal frequency. However, the interaction is unstable, and MTs frequently become detached. This phenotype is rescued by ectopic expression of the MT plus end–stabilizing factor CLASP, but not by artificial shortening of MTs. We show that human kinesin-8 (KIF18A) is also important to ensure proper MT attachment. Overall, these results suggest that the MT-stabilizing activity of kinesin-8 is critical for stable kinetochore–MT attachment.
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Affiliation(s)
- Tomoya Edzuka
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Japan.,Marine Biological Laboratory, Woods Hole, MA
| | - Gohta Goshima
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Japan .,Marine Biological Laboratory, Woods Hole, MA
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60
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Thoms D, Vineyard L, Elliott A, Shaw SL. CLASP Facilitates Transitions between Cortical Microtubule Array Patterns. PLANT PHYSIOLOGY 2018; 178:1551-1567. [PMID: 30327382 PMCID: PMC6288741 DOI: 10.1104/pp.18.00961] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 10/07/2018] [Indexed: 05/23/2023]
Abstract
Acentrosomal plant microtubule arrays form patterns at the cell cortex that influence cellular morphogenesis by templating the deposition of cell wall materials, but the molecular basis by which the microtubules form the cortical array patterns remains largely unknown. Loss of the Arabidopsis (Arabidopsis thaliana) microtubule-associated protein, CYTOPLASMIC LINKER ASSOCIATED PROTEIN (AtCLASP), results in cellular growth anisotropy defects in hypocotyl cells. We examined the microtubule array patterning in atclasp-1 null mutants and discovered a significant defect in the timing of transitions between array patterns but no substantive defect in the array patterns per se. Detailed analysis and computational modeling of the microtubule dynamics in two atclasp-1 fluorescent tubulin marker lines revealed marker-dependent effects on depolymerization and catastrophe frequency predicted to alter the steady-state microtubule population. Quantitative in vivo analysis of the underlying microtubule array architecture showed that AtCLASP is required to maintain the number of growing microtubule plus ends during transitions between array patterns. We propose that AtCLASP plays a critical role in cellular morphogenesis through actions on new microtubules that facilitate array transitions.
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Affiliation(s)
- David Thoms
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Laura Vineyard
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Andrew Elliott
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Sidney L Shaw
- Department of Biology, Indiana University, Bloomington, Indiana 47405
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61
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Nakos K, Rosenberg M, Spiliotis ET. Regulation of microtubule plus end dynamics by septin 9. Cytoskeleton (Hoboken) 2018; 76:83-91. [PMID: 30144301 DOI: 10.1002/cm.21488] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 07/05/2018] [Accepted: 08/10/2018] [Indexed: 12/18/2022]
Abstract
Septins are GTP-binding proteins that associate with the microtubule (MT) and actin cytoskeleton. Septins affect MT organization and posttranslational modifications, but their role in MT dynamics is less understood. Here, we reconstituted MT dynamics in the presence of the MT-binding septin (SEPT9) using an in vitro cell-free assay, which images the polymerization of tubulin from guanosine-5'-[(α,β)-methyleno]triphosphate (GMPCPP)-stabilized MT seeds. We found that submicromolar concentrations of SEPT9 suppress MT catastrophe and enhance the growth of MT plus ends to great lengths, while low micromolar concentrations of SEPT9 stabilize MTs by inhibiting dynamic instability. We show that SEPT9 associates preferentially with the lattice of GMPCPP-stabilized MT seeds and surprisingly recruits soluble tubulin to the MT lattice. Notably, the effects of SEPT9 on MT dynamics are dependent on its G-G dimerization interface, which is formed by the pockets of the GTP-binding domains. A mutation (H530D) that disrupts G-G dimerization abrogates the effects of SEPT9 on MT dynamics and diminishes its ability to recruit tubulin to the MT lattice. Taken together, these results suggest that SEPT9 promotes the formation and maintenance of long stable MTs through a mechanism that may involve recruitment of unpolymerized tubulin to the MT lattice.
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Affiliation(s)
| | | | - Elias T Spiliotis
- Department of Biology, Drexel University, Philadelphia, Pennsylvania
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62
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Nithianantham S, Cook BD, Beans M, Guo F, Chang F, Al-Bassam J. Structural basis of tubulin recruitment and assembly by microtubule polymerases with tumor overexpressed gene (TOG) domain arrays. eLife 2018; 7:38922. [PMID: 30422110 PMCID: PMC6251626 DOI: 10.7554/elife.38922] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 10/31/2018] [Indexed: 12/21/2022] Open
Abstract
XMAP215/Stu2/Alp14 proteins accelerate microtubule plus-end polymerization by recruiting tubulins via arrays of tumor overexpressed gene (TOG) domains, yet their mechanism remains unknown. Here, we describe the biochemical and structural basis for TOG arrays in recruiting and polymerizing tubulins. Alp14 binds four tubulins via dimeric TOG1-TOG2 subunits, in which each domain exhibits a distinct exchange rate for tubulin. X-ray structures revealed square-shaped assemblies composed of pseudo-dimeric TOG1-TOG2 subunits assembled head-to-tail, positioning four unpolymerized tubulins in a polarized wheel-like configuration. Crosslinking and electron microscopy show Alp14-tubulin forms square assemblies in solution, and inactivating their interfaces destabilize this organization without influencing tubulin binding. An X-ray structure determined using approach to modulate tubulin polymerization revealed an unfurled assembly, in which TOG1-TOG2 uniquely bind to two polymerized tubulins. Our findings suggest a new microtubule polymerase model in which TOG arrays recruit tubulins by forming square assemblies that then unfurl, facilitating their concerted polymerization into protofilaments.
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Affiliation(s)
- Stanley Nithianantham
- Molecular Cellular Biology Department, University of California, Davis, United States
| | - Brian D Cook
- Molecular Cellular Biology Department, University of California, Davis, United States
| | - Madeleine Beans
- Molecular Cellular Biology Department, University of California, Davis, United States
| | - Fei Guo
- Molecular Cellular Biology Department, University of California, Davis, United States
| | - Fred Chang
- Department of Cell and Tissue Biology, University of California, San Francisco, United States
| | - Jawdat Al-Bassam
- Molecular Cellular Biology Department, University of California, Davis, United States
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63
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Vemu A, Szczesna E, Zehr EA, Spector JO, Grigorieff N, Deaconescu AM, Roll-Mecak A. Severing enzymes amplify microtubule arrays through lattice GTP-tubulin incorporation. Science 2018; 361:eaau1504. [PMID: 30139843 PMCID: PMC6510489 DOI: 10.1126/science.aau1504] [Citation(s) in RCA: 133] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 07/18/2018] [Indexed: 12/16/2022]
Abstract
Spastin and katanin sever and destabilize microtubules. Paradoxically, despite their destructive activity they increase microtubule mass in vivo. We combined single-molecule total internal reflection fluorescence microscopy and electron microscopy to show that the elemental step in microtubule severing is the generation of nanoscale damage throughout the microtubule by active extraction of tubulin heterodimers. These damage sites are repaired spontaneously by guanosine triphosphate (GTP)-tubulin incorporation, which rejuvenates and stabilizes the microtubule shaft. Consequently, spastin and katanin increase microtubule rescue rates. Furthermore, newly severed ends emerge with a high density of GTP-tubulin that protects them against depolymerization. The stabilization of the newly severed plus ends and the higher rescue frequency synergize to amplify microtubule number and mass. Thus, severing enzymes regulate microtubule architecture and dynamics by promoting GTP-tubulin incorporation within the microtubule shaft.
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Affiliation(s)
- Annapurna Vemu
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Ewa Szczesna
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Elena A Zehr
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Jeffrey O Spector
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Nikolaus Grigorieff
- Howard Hughes Medical Institute, Brandeis University, Waltham, MA 02454, USA
| | - Alexandra M Deaconescu
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI 02903, USA
| | - Antonina Roll-Mecak
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA.
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, Bethesda, MD 20892, USA
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64
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Abstract
Microtubules are dynamic polymers of αβ-tubulin that are essential for intracellular organization, organelle trafficking and chromosome segregation. Microtubule growth and shrinkage occur via addition and loss of αβ-tubulin subunits, which are biochemical processes. Dynamic microtubules can also engage in mechanical processes, such as exerting forces by pushing or pulling against a load. Recent advances at the intersection of biochemistry and mechanics have revealed the existence of multiple conformations of αβ-tubulin subunits and their central role in dictating the mechanisms of microtubule dynamics and force generation. It has become apparent that microtubule-associated proteins (MAPs) selectively target specific tubulin conformations to regulate microtubule dynamics, and mechanical forces can also influence microtubule dynamics by altering the balance of tubulin conformations. Importantly, the conformational states of tubulin dimers are likely to be coupled throughout the lattice: the conformation of one dimer can influence the conformation of its nearest neighbours, and this effect can propagate over longer distances. This coupling provides a long-range mechanism by which MAPs and forces can modulate microtubule growth and shrinkage. These findings provide evidence that the interplay between biochemistry and mechanics is essential for the cellular functions of microtubules.
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Affiliation(s)
- Gary J Brouhard
- Department of Biology, McGill University, Montréal, Quebec, Canada.
| | - Luke M Rice
- Department of Biophysics, University of Texas Southwestern, Dallas, TX, USA.
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Aher A, Kok M, Sharma A, Rai A, Olieric N, Rodriguez-Garcia R, Katrukha EA, Weinert T, Olieric V, Kapitein LC, Steinmetz MO, Dogterom M, Akhmanova A. CLASP Suppresses Microtubule Catastrophes through a Single TOG Domain. Dev Cell 2018; 46:40-58.e8. [PMID: 29937387 PMCID: PMC6035287 DOI: 10.1016/j.devcel.2018.05.032] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 04/13/2018] [Accepted: 05/25/2018] [Indexed: 01/05/2023]
Abstract
The dynamic instability of microtubules plays a key role in controlling their organization and function, but the cellular mechanisms regulating this process are poorly understood. Here, we show that cytoplasmic linker-associated proteins (CLASPs) suppress transitions from microtubule growth to shortening, termed catastrophes, including those induced by microtubule-destabilizing agents and physical barriers. Mammalian CLASPs encompass three TOG-like domains, TOG1, TOG2, and TOG3, none of which bind to free tubulin. TOG2 is essential for catastrophe suppression, whereas TOG3 mildly enhances rescues but cannot suppress catastrophes. These functions are inhibited by the C-terminal domain of CLASP2, while the TOG1 domain can release this auto-inhibition. TOG2 fused to a positively charged microtubule-binding peptide autonomously accumulates at growing but not shrinking ends, suppresses catastrophes, and stimulates rescues. CLASPs suppress catastrophes by stabilizing growing microtubule ends, including incomplete ones, preventing their depolymerization and promoting their recovery into complete tubes. TOG2 domain is the key determinant of these activities. CLASPs potently suppress microtubule catastrophes induced by different mechanisms CLASPs act by stabilizing growing microtubule ends, including incomplete ones CLASP2 TOG-like domain, TOG2, is necessary and sufficient for catastrophe inhibition TOG2 fused to a positively charged peptide accumulates at growing microtubule ends
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Affiliation(s)
- Amol Aher
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Maurits Kok
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Ashwani Sharma
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Ankit Rai
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Natacha Olieric
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Ruddi Rodriguez-Garcia
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Eugene A Katrukha
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Tobias Weinert
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Vincent Olieric
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Lukas C Kapitein
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland; University of Basel, Biozentrum, 4056 Basel, Switzerland
| | - Marileen Dogterom
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Anna Akhmanova
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
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66
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CLASP promotes stable tethering of endoplasmic microtubules to the cell cortex to maintain cytoplasmic stability in Arabidopsis meristematic cells. PLoS One 2018; 13:e0198521. [PMID: 29894477 PMCID: PMC5997327 DOI: 10.1371/journal.pone.0198521] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 05/21/2018] [Indexed: 12/15/2022] Open
Abstract
Following cytokinesis in plants, Endoplasmic MTs (EMTs) assemble on the nuclear surface, forming a radial network that extends out to the cell cortex, where they attach and incorporate into the cortical microtubule (CMT) array. We found that in these post-cytokinetic cells, the MT-associated protein CLASP is enriched at sites of EMT-cortex attachment, and is required for stable EMT tethering and growth into the cell cortex. Loss of EMT-cortex anchoring in clasp-1 mutants results in destabilized EMT arrays, and is accompanied by enhanced mobility of the cytoplasm, premature vacuolation, and precocious entry into cell elongation phase. Thus, EMTs appear to maintain cells in a meristematic state by providing a structural scaffold that stabilizes the cytoplasm to counteract actomyosin-based cytoplasmic streaming forces, thereby preventing premature establishment of a central vacuole and rapid cell elongation.
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67
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Cassimeris L, Leung JC, Odde DJ. Monte Carlo simulations of microtubule arrays: The critical roles of rescue transitions, the cell boundary, and tubulin concentration in shaping microtubule distributions. PLoS One 2018; 13:e0197538. [PMID: 29782540 PMCID: PMC5962052 DOI: 10.1371/journal.pone.0197538] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 05/03/2018] [Indexed: 01/12/2023] Open
Abstract
Microtubules are dynamic polymers required for a number of processes, including chromosome movement in mitosis. While regulators of microtubule dynamics have been well characterized, we lack a convenient way to predict how the measured dynamic parameters shape the entire microtubule system within a cell, or how the system responds when specific parameters change in response to internal or external signals. Here we describe a Monte Carlo model to simulate an array of dynamic microtubules from parameters including the cell radius, total tubulin concentration, microtubule nucleation rate from the centrosome, and plus end dynamic instability. The algorithm also allows dynamic instability or position of the cell edge to vary during the simulation. Outputs from simulations include free tubulin concentration, average microtubule lengths, length distributions, and individual length changes over time. Using this platform and reported parameters measured in interphase LLCPK1 epithelial cells, we predict that sequestering ~ 15-20% of total tubulin results in fewer microtubules, but promotes dynamic instability of those remaining. Simulations also predict that lowering nucleation rate will increase the stability and average length of the remaining microtubules. Allowing the position of the cell's edge to vary over time changed the average length but not the number of microtubules and generated length distributions consistent with experimental measurements. Simulating the switch from interphase to prophase demonstrated that decreased rescue frequency at prophase is the critical factor needed to rapidly clear the cell of interphase microtubules prior to mitotic spindle assembly. Finally, consistent with several previous simulations, our results demonstrate that microtubule nucleation and dynamic instability in a confined space determines the partitioning of tubulin between monomer and polymer pools. The model and simulations will be useful for predicting changes to the entire microtubule array after modification to one or more parameters, including predicting the effects of tubulin-targeted chemotherapies.
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Affiliation(s)
- Lynne Cassimeris
- Dept. of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, United States of America
| | - Jessica C Leung
- Dept. of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, United States of America
| | - David J Odde
- Dept. of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, United States of America
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68
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Majumdar S, Kim T, Chen Z, Munyoki S, Tso SC, Brautigam CA, Rice LM. An isolated CLASP TOG domain suppresses microtubule catastrophe and promotes rescue. Mol Biol Cell 2018; 29:1359-1375. [PMID: 29851564 PMCID: PMC5994897 DOI: 10.1091/mbc.e17-12-0748] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Microtubules are heavily regulated dynamic polymers of αβ-tubulin that are required for proper chromosome segregation and organization of the cytoplasm. Polymerases in the XMAP215 family use arrayed TOG domains to promote faster microtubule elongation. Regulatory factors in the cytoplasmic linker associated protein (CLASP) family that reduce catastrophe and/or increase rescue also contain arrayed TOGs, but how CLASP TOGs contribute to activity is poorly understood. Here, using Saccharomyces cerevisiae Stu1 as a model CLASP, we report structural, biochemical, and reconstitution studies that clarify functional properties of CLASP TOGs. The two TOGs in Stu1 have very different tubulin-binding properties: TOG2 binds to both unpolymerized and polymerized tubulin, and TOG1 binds very weakly to either. The structure of Stu1-TOG2 reveals a CLASP-specific residue that likely confers distinctive tubulin-binding properties. The isolated TOG2 domain strongly suppresses microtubule catastrophe and increases microtubule rescue in vitro, contradicting the expectation that regulatory activity requires an array of TOGs. Single point mutations on the tubulin-binding surface of TOG2 ablate its anti-catastrophe and rescue activity in vitro, and Stu1 function in cells. Revealing that an isolated CLASP TOG can regulate polymerization dynamics without being part of an array provides insight into the mechanism of CLASPs and diversifies the understanding of TOG function.
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Affiliation(s)
- Shreoshi Majumdar
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Tae Kim
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Zhe Chen
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390
| | - Sarah Munyoki
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Shih-Chia Tso
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390
| | - Chad A Brautigam
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390.,Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390
| | - Luke M Rice
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
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69
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Lawrence EJ, Arpag G, Norris SR, Zanic M. Human CLASP2 specifically regulates microtubule catastrophe and rescue. Mol Biol Cell 2018. [PMID: 29540526 PMCID: PMC5935067 DOI: 10.1091/mbc.e18-01-0016] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Cytoplasmic linker-associated proteins (CLASPs) are microtubule-associated proteins essential for microtubule regulation in many cellular processes. However, the molecular mechanisms underlying CLASP activity are not understood. Here, we use purified protein components and total internal reflection fluorescence microscopy to investigate the effects of human CLASP2 on microtubule dynamics in vitro. We demonstrate that CLASP2 suppresses microtubule catastrophe and promotes rescue without affecting the rates of microtubule growth or shrinkage. Strikingly, when CLASP2 is combined with EB1, a known binding partner, the effects on microtubule dynamics are strongly enhanced. We show that synergy between CLASP2 and EB1 is dependent on a direct interaction, since a truncated EB1 protein that lacks the CLASP2-binding domain does not enhance CLASP2 activity. Further, we find that EB1 targets CLASP2 to microtubules and increases the dwell time of CLASP2 at microtubule tips. Although the temporally averaged microtubule growth rates are unaffected by CLASP2, we find that microtubules grown with CLASP2 display greater variability in growth rates. Our results provide insight into the regulation of microtubule dynamics by CLASP proteins and highlight the importance of the functional interplay between regulatory proteins at dynamic microtubule ends.
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Affiliation(s)
- Elizabeth J Lawrence
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240
| | - Göker Arpag
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240
| | - Stephen R Norris
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240
| | - Marija Zanic
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240.,Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37240.,Department of Biochemistry, Vanderbilt University, Nashville, TN 37240
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70
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Mei Y, Wright KM, Haegeman A, Bauters L, Diaz-Granados A, Goverse A, Gheysen G, Jones JT, Mantelin S. The Globodera pallida SPRYSEC Effector GpSPRY-414-2 That Suppresses Plant Defenses Targets a Regulatory Component of the Dynamic Microtubule Network. FRONTIERS IN PLANT SCIENCE 2018; 9:1019. [PMID: 30050557 PMCID: PMC6052128 DOI: 10.3389/fpls.2018.01019] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 06/22/2018] [Indexed: 05/09/2023]
Abstract
The white potato cyst nematode, Globodera pallida, is an obligate biotrophic pathogen of a limited number of Solanaceous plants. Like other plant pathogens, G. pallida deploys effectors into its host that manipulate the plant to the benefit of the nematode. Genome analysis has led to the identification of large numbers of candidate effectors from this nematode, including the cyst nematode-specific SPRYSEC proteins. These are a secreted subset of a hugely expanded gene family encoding SPRY domain-containing proteins, many of which remain to be characterized. We investigated the function of one of these SPRYSEC effector candidates, GpSPRY-414-2. Expression of the gene encoding GpSPRY-414-2 is restricted to the dorsal pharyngeal gland cell and reducing its expression in G. pallida infective second stage juveniles using RNA interference causes a reduction in parasitic success on potato. Transient expression assays in Nicotiana benthamiana indicated that GpSPRY-414-2 disrupts plant defenses. It specifically suppresses effector-triggered immunity (ETI) induced by co-expression of the Gpa2 resistance gene and its cognate avirulence factor RBP-1. It also causes a reduction in the production of reactive oxygen species triggered by exposure of plants to the bacterial flagellin epitope flg22. Yeast two-hybrid screening identified a potato cytoplasmic linker protein (CLIP)-associated protein (StCLASP) as a host target of GpSPRY-414-2. The two proteins co-localize in planta at the microtubules. CLASPs are members of a conserved class of microtubule-associated proteins that contribute to microtubule stability and growth. However, disruption of the microtubule network does not prevent suppression of ETI by GpSPRY-414-2 nor the interaction of the effector with its host target. Besides, GpSPRY-414-2 stabilizes its target while effector dimerization and the formation of high molecular weight protein complexes including GpSPRY-414-2 are prompted in the presence of the StCLASP. These data indicate that the nematode effector GpSPRY-414-2 targets the microtubules to facilitate infection.
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Affiliation(s)
- Yuanyuan Mei
- Dundee Effector Consortium, Cell and Molecular Sciences Group, The James Hutton Institute, Dundee, United Kingdom
- Faculty of Bioscience Engineering, Department of Biotechnology, Ghent University, Ghent, Belgium
| | - Kathryn M. Wright
- Dundee Effector Consortium, Cell and Molecular Sciences Group, The James Hutton Institute, Dundee, United Kingdom
| | - Annelies Haegeman
- Faculty of Bioscience Engineering, Department of Biotechnology, Ghent University, Ghent, Belgium
| | - Lander Bauters
- Faculty of Bioscience Engineering, Department of Biotechnology, Ghent University, Ghent, Belgium
| | - Amalia Diaz-Granados
- Laboratory of Nematology, Department of Plant Sciences, Wageningen University, Wageningen, Netherlands
| | - Aska Goverse
- Laboratory of Nematology, Department of Plant Sciences, Wageningen University, Wageningen, Netherlands
| | - Godelieve Gheysen
- Faculty of Bioscience Engineering, Department of Biotechnology, Ghent University, Ghent, Belgium
| | - John T. Jones
- Dundee Effector Consortium, Cell and Molecular Sciences Group, The James Hutton Institute, Dundee, United Kingdom
- School of Biology, University of St Andrews, St Andrews, United Kingdom
| | - Sophie Mantelin
- Dundee Effector Consortium, Cell and Molecular Sciences Group, The James Hutton Institute, Dundee, United Kingdom
- *Correspondence: Sophie Mantelin
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71
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Zhu SH, Xue F, Li YJ, Liu F, Zhang XY, Zhao LJ, Sun YQ, Zhu QH, Sun J. Identification and Functional Characterization of a Microtubule-Associated Protein, GhCLASP2, From Upland Cotton ( Gossypium hirsutum L.). FRONTIERS IN PLANT SCIENCE 2018; 9:882. [PMID: 29997641 PMCID: PMC6030384 DOI: 10.3389/fpls.2018.00882] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 06/06/2018] [Indexed: 05/10/2023]
Abstract
Cytoplasmic linker-associated proteins (CLASPs) are microtubule-associated proteins (MAPs) involved in regulation of dynamics of microtubules (MTs) that play an important role in plant growth and development. In this study, we identified cotton CLASP genes and investigated the function of GhCLASP2. GhCLASP2 was mainly expressed in stem and developing fibers, especially in fibers of the secondary cell wall deposition stage. Ectopic expression of GhCLASP2 in Arabidopsis increased the branching number of leaf trichomes and rescued the defective phenotypes of clasp-1. In cotton, overexpression of GhCLASP2 increased fiber strength, probably related to enhanced expression levels of tubulin, cellulose synthase, and expansin genes. Suppression of GhCLASP2 caused shorter internodes and semi-dwarfism, abnormal flower stigma, aborted anthers without pollen grains, and sterility. These changed phenotypes were similar to those observed in the Arabidopsis clasp-1 mutant. GhCLASP2 was co-localized with MTs according to transient experiment. These results suggest that GhCLASP2 functions similarly as AtCLASP, acting as a MAP and controlling cotton growth and development by regulating MTs.
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Affiliation(s)
- Shou-Hong Zhu
- The Key Laboratory of Oasis Eco-Agriculture, College of Agriculture, Shihezi University, Shihezi, China
| | - Fei Xue
- The Key Laboratory of Oasis Eco-Agriculture, College of Agriculture, Shihezi University, Shihezi, China
| | - Yan-Jun Li
- The Key Laboratory of Oasis Eco-Agriculture, College of Agriculture, Shihezi University, Shihezi, China
| | - Feng Liu
- The Key Laboratory of Oasis Eco-Agriculture, College of Agriculture, Shihezi University, Shihezi, China
| | - Xin-Yu Zhang
- The Key Laboratory of Oasis Eco-Agriculture, College of Agriculture, Shihezi University, Shihezi, China
| | - Lan-Jie Zhao
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
| | - Yu-Qiang Sun
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, China
| | - Qian-Hao Zhu
- CSIRO Agriculture and Food, Canberra, ACT, Australia
- *Correspondence: Qian-Hao Zhu, Jie Sun,
| | - Jie Sun
- The Key Laboratory of Oasis Eco-Agriculture, College of Agriculture, Shihezi University, Shihezi, China
- *Correspondence: Qian-Hao Zhu, Jie Sun,
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72
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Barsegov V, Ross JL, Dima RI. Dynamics of microtubules: highlights of recent computational and experimental investigations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:433003. [PMID: 28812545 DOI: 10.1088/1361-648x/aa8670] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Microtubules are found in most eukaryotic cells, with homologs in eubacteria and archea, and they have functional roles in mitosis, cell motility, intracellular transport, and the maintenance of cell shape. Numerous efforts have been expended over the last two decades to characterize the interactions between microtubules and the wide variety of microtubule associated proteins that control their dynamic behavior in cells resulting in microtubules being assembled and disassembled where and when they are required by the cell. We present the main findings regarding microtubule polymerization and depolymerization and review recent work about the molecular motors that modulate microtubule dynamics by inducing either microtubule depolymerization or severing. We also discuss the main experimental and computational approaches used to quantify the thermodynamics and mechanics of microtubule filaments.
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Affiliation(s)
- Valeri Barsegov
- Department of Chemistry, University of Massachusetts, Lowell, MA 01854, United States of America
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73
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Myer NM, Myers KA. CLASP1 regulates endothelial cell branching morphology and directed migration. Biol Open 2017; 6:1502-1515. [PMID: 28860131 PMCID: PMC5665473 DOI: 10.1242/bio.028571] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Endothelial cell (EC) branching is critically dependent upon the dynamic nature of the microtubule (MT) cytoskeleton. Extracellular matrix (ECM) mechanosensing is a prominent mechanism by which cytoskeletal reorganization is achieved; yet how ECM-induced signaling is able to target cytoskeletal reorganization intracellularly to facilitate productive EC branching morphogenesis is not known. Here, we tested the hypothesis that the composition and density of the ECM drive the regulation of MT growth dynamics in ECs by targeting the MT stabilizing protein, cytoplasmic linker associated protein 1 (CLASP1). High-resolution fluorescent microscopy coupled with computational image analysis reveal that CLASP1 promotes slow MT growth on glass ECMs and promotes short-lived MT growth on high-density collagen-I and fibronectin ECMs. Within EC branches, engagement of either high-density collagen-I or high-density fibronectin ECMs results in reduced MT growth speeds, while CLASP1-dependent effects on MT dynamics promotes elevated numbers of short, branched protrusions that guide persistent and directed EC migration. Summary: CLASP1 modulates microtubule dynamics with sub-cellular specificity in response to extracellular matrix density and composition. CLASP1 effects on microtubules promote short, branched protrusions that guide persistent and directional EC migration. This article has an associated First Person interview with the first author of the paper as part of the supplementary information.
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Affiliation(s)
- Nicole M Myer
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia PA 19104, USA
| | - Kenneth A Myers
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia PA 19104, USA
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74
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Yukawa M, Kawakami T, Okazaki M, Kume K, Tang NH, Toda T. A microtubule polymerase cooperates with the kinesin-6 motor and a microtubule cross-linker to promote bipolar spindle assembly in the absence of kinesin-5 and kinesin-14 in fission yeast. Mol Biol Cell 2017; 28:3647-3659. [PMID: 29021344 PMCID: PMC5706992 DOI: 10.1091/mbc.e17-08-0497] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 09/26/2017] [Accepted: 10/03/2017] [Indexed: 12/16/2022] Open
Abstract
Kinesin-5 is required for bipolar spindle assembly; yet in the absence of kinesins-5 and -14, cells can form spindles. In fission yeast, three distinct pathways compensate for their loss. Microtubule polymerase, kinesin-6, and microtubule cross-linker execute individual roles in concert at different mitotic stages in place of the two kinesins. Accurate chromosome segregation relies on the bipolar mitotic spindle. In many eukaryotes, spindle formation is driven by the plus-end–directed motor kinesin-5 that generates outward force to establish spindle bipolarity. Its inhibition leads to the emergence of monopolar spindles with mitotic arrest. Intriguingly, simultaneous inactivation of the minus-end–directed motor kinesin-14 restores spindle bipolarity in many systems. Here we show that in fission yeast, three independent pathways contribute to spindle bipolarity in the absence of kinesin-5/Cut7 and kinesin-14/Pkl1. One is kinesin-6/Klp9 that engages with spindle elongation once short bipolar spindles assemble. Klp9 also ensures the medial positioning of anaphase spindles to prevent unequal chromosome segregation. Another is the Alp7/TACC-Alp14/TOG microtubule polymerase complex. Temperature-sensitive alp7cut7pkl1 mutants are arrested with either monopolar or very short spindles. Forced targeting of Alp14 to the spindle pole body is sufficient to render alp7cut7pkl1 triply deleted cells viable and promote spindle assembly, indicating that Alp14-mediated microtubule polymerization from the nuclear face of the spindle pole body could generate outward force in place of Cut7 during early mitosis. The third pathway involves the Ase1/PRC1 microtubule cross-linker that stabilizes antiparallel microtubules. Our study, therefore, unveils multifaceted interplay among kinesin-dependent and -independent pathways leading to mitotic bipolar spindle assembly.
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Affiliation(s)
- Masashi Yukawa
- Hiroshima Research Center for Healthy Aging, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan .,Laboratory of Molecular and Chemical Cell Biology, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Tomoki Kawakami
- Hiroshima Research Center for Healthy Aging, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan.,Laboratory of Molecular and Chemical Cell Biology, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Masaki Okazaki
- Hiroshima Research Center for Healthy Aging, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan.,Laboratory of Molecular and Chemical Cell Biology, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Kazunori Kume
- Hiroshima Research Center for Healthy Aging, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan.,Laboratory of Cell Biology, Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Ngang Heok Tang
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Takashi Toda
- Hiroshima Research Center for Healthy Aging, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan .,Laboratory of Molecular and Chemical Cell Biology, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
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75
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Vemu A, Atherton J, Spector JO, Moores CA, Roll-Mecak A. Tubulin isoform composition tunes microtubule dynamics. Mol Biol Cell 2017; 28:3564-3572. [PMID: 29021343 PMCID: PMC5706985 DOI: 10.1091/mbc.e17-02-0124] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 09/25/2017] [Accepted: 10/03/2017] [Indexed: 12/30/2022] Open
Abstract
We report the cryo-EM structure and dynamic parameters for unmodified α1B/βI+βIVb microtubules. These microtubules display markedly different dynamics compared to heterogeneous brain microtubules, and their dynamic parameters can be proportionally tuned by the addition of a recombinant neuronal tubulin isoform with different dynamic properties. Microtubules polymerize and depolymerize stochastically, a behavior essential for cell division, motility, and differentiation. While many studies advanced our understanding of how microtubule-associated proteins tune microtubule dynamics in trans, we have yet to understand how tubulin genetic diversity regulates microtubule functions. The majority of in vitro dynamics studies are performed with tubulin purified from brain tissue. This preparation is not representative of tubulin found in many cell types. Here we report the 4.2-Å cryo-electron microscopy (cryo-EM) structure and in vitro dynamics parameters of α1B/βI+βIVb microtubules assembled from tubulin purified from a human embryonic kidney cell line with isoform composition characteristic of fibroblasts and many immortalized cell lines. We find that these microtubules grow faster and transition to depolymerization less frequently compared with brain microtubules. Cryo-EM reveals that the dynamic ends of α1B/βI+βIVb microtubules are less tapered and that these tubulin heterodimers display lower curvatures. Interestingly, analysis of EB1 distributions at dynamic ends suggests no differences in GTP cap sizes. Last, we show that the addition of recombinant α1A/βIII tubulin, a neuronal isotype overexpressed in many tumors, proportionally tunes the dynamics of α1B/βI+βIVb microtubules. Our study is an important step toward understanding how tubulin isoform composition tunes microtubule dynamics.
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Affiliation(s)
- Annapurna Vemu
- Cell Biology and Biophysics Unit, National Institute of Neurological Disorders and Stroke, Lung and Blood Institute, Bethesda, MD 20892
| | - Joseph Atherton
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, University of London, London WC1E 7HX, United Kingdom
| | - Jeffrey O Spector
- Cell Biology and Biophysics Unit, National Institute of Neurological Disorders and Stroke, Lung and Blood Institute, Bethesda, MD 20892
| | - Carolyn A Moores
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, University of London, London WC1E 7HX, United Kingdom
| | - Antonina Roll-Mecak
- Cell Biology and Biophysics Unit, National Institute of Neurological Disorders and Stroke, Lung and Blood Institute, Bethesda, MD 20892 .,Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD 20892
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76
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Lu A, Zhou CJ, Wang DH, Han Z, Kong XW, Ma YZ, Yun ZZ, Liang CG. Cytoskeleton-associated protein 5 and clathrin heavy chain binding regulates spindle assembly in mouse oocytes. Oncotarget 2017; 8:17491-17503. [PMID: 28177917 PMCID: PMC5392264 DOI: 10.18632/oncotarget.15097] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 01/24/2017] [Indexed: 11/25/2022] Open
Abstract
Mammalian oocyte meiotic maturation is the precondition of early embryo development. Lots of microtubules (MT)-associated proteins participate in oocyte maturation process. Cytoskeleton-associated protein 5 (CKAP5) is a member of the XMAP215 family that regulates microtubule dynamics during mitosis. However, its role in meiosis has not been fully studied. Here, we investigated the function of CKAP5 in mouse oocyte meiotic maturation and early embryo development. Western blot showed that CKAP5 expression increased from GVBD, maintaining at high level at metaphase, and decreased after late 1-cell stage. Confocal microscopy showed there is no specific accumulation of CKAP5 at interphase (GV, PN or 2-cell stage). However, once cells enter into meiotic or mitotic division, CKAP5 was localized at the whole spindle apparatus. Treatment of oocytes with the tubulin-disturbing reagents nocodazole (induces MTs depolymerization) or taxol (prevents MTs depolymerization) did not affect CKAP5 expression but led to a rearrangement of CKAP5. Further, knock-down of CKAP5 resulted in a failure of first polar body extrusion, serious defects in spindle assembly, and failure of chromosome alignment. Loss of CKAP5 also decreased early embryo development potential. Furthermore, co-immunoprecipitation showed that CKAP5 bound to clathrin heavy chain 1 (CLTC). Taken together, our results demonstrate that CKAP5 is important in oocyte maturation and early embryo development, and CKAP5 might work together with CLTC in mouse oocyte maturation.
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Affiliation(s)
- Angeleem Lu
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, The Research Center for Laboratory Animal Science, College of Life Science, Inner Mongolia University, Inner Mongolia, People's Republic of China
| | - Cheng-Jie Zhou
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, The Research Center for Laboratory Animal Science, College of Life Science, Inner Mongolia University, Inner Mongolia, People's Republic of China
| | - Dong-Hui Wang
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, The Research Center for Laboratory Animal Science, College of Life Science, Inner Mongolia University, Inner Mongolia, People's Republic of China
| | - Zhe Han
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, The Research Center for Laboratory Animal Science, College of Life Science, Inner Mongolia University, Inner Mongolia, People's Republic of China
| | - Xiang-Wei Kong
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, The Research Center for Laboratory Animal Science, College of Life Science, Inner Mongolia University, Inner Mongolia, People's Republic of China
| | - Yu-Zhen Ma
- Inner Mongolia People's Hospital, Hohhot, Inner Mongolia, People's Republic of China
| | - Zhi-Zhong Yun
- Inner Mongolia People's Hospital, Hohhot, Inner Mongolia, People's Republic of China
| | - Cheng-Guang Liang
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, The Research Center for Laboratory Animal Science, College of Life Science, Inner Mongolia University, Inner Mongolia, People's Republic of China
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77
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Hess H, Ross JL. Non-equilibrium assembly of microtubules: from molecules to autonomous chemical robots. Chem Soc Rev 2017; 46:5570-5587. [PMID: 28329028 PMCID: PMC5603359 DOI: 10.1039/c7cs00030h] [Citation(s) in RCA: 131] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Biological systems have evolved to harness non-equilibrium processes from the molecular to the macro scale. It is currently a grand challenge of chemistry, materials science, and engineering to understand and mimic biological systems that have the ability to autonomously sense stimuli, process these inputs, and respond by performing mechanical work. New chemical systems are responding to the challenge and form the basis for future responsive, adaptive, and active materials. In this article, we describe a particular biochemical-biomechanical network based on the microtubule cytoskeletal filament - itself a non-equilibrium chemical system. We trace the non-equilibrium aspects of the system from molecules to networks and describe how the cell uses this system to perform active work in essential processes. Finally, we discuss how microtubule-based engineered systems can serve as testbeds for autonomous chemical robots composed of biological and synthetic components.
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Affiliation(s)
- H Hess
- Department of Biomedical Engineering, Columbia University, USA.
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78
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Shevchenko GV. Putative gravisensors among microtubule associated proteins. Cell Biol Int 2017; 43:983-990. [PMID: 28656641 DOI: 10.1002/cbin.10811] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 06/24/2017] [Indexed: 12/27/2022]
Abstract
Despite of long period of investigation (over 100 years), still a lot of questions remain unclear about molecular mechanisms of plant graviperception. This requires designing new experiments and new approaches to be applied in gravitational biology. Investigation of plant cell reactions under clinorotation (plant disorientation in respect to gravity vector) is of significant importance to such type of research. Clinorotation is known to cause changes of cell polarity and exert mechanical stress in plant cells. Microtubular cytoskeleton is highly dynamic structure and it responds to both of these stresses. Due to turgor pressure and cell elongation, endogenous mechanical forces influence microtubule orientation in order to coordinate cell growth. Rearrangements of microtubules are regulated by numerous associated proteins which functional activity is not fully clear. In this review, we discuss how MT associated proteins regulate cortical MT arrays under mechanical stress and consider how these proteins may act as plant cell gravisensors. Investigation of microtubule associated proteins under clinorotation might shed the light on molecular mechanism of plant cytoskeleton arrangement and its involvement in initial reactions of cell graviperception.
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Affiliation(s)
- Galina V Shevchenko
- Institute of Botany, NAS Ukraine, Cell Biology Department, 2, Tereshchenkivska St., Kiev, 01004, Ukraine
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79
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Roostalu J, Surrey T. Microtubule nucleation: beyond the template. Nat Rev Mol Cell Biol 2017; 18:702-710. [PMID: 28831203 DOI: 10.1038/nrm.2017.75] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Microtubules are cytoskeletal filaments central to a wide range of essential cellular functions in eukaryotic cells. Consequently, cells need to exert tight control over when, where and how many microtubules are being made. Whereas the regulation of microtubule dynamics is well studied, the molecular mechanisms of microtubule nucleation are still poorly understood. Next to the established master template of nucleation, the γ-tubulin ring complex, other microtubule-associated proteins that affect microtubule dynamic properties have recently been found to contribute to nucleation. It has begun to emerge that the nucleation efficiency is controlled not only by template activity but also by, either additionally or alternatively, the stabilization of the nascent microtubule 'nucleus'. This suggests a simple conceptual framework for the mechanisms regulating microtubule nucleation in cells.
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Affiliation(s)
| | - Thomas Surrey
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
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80
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Vleugel M, Kok M, Dogterom M. Understanding force-generating microtubule systems through in vitro reconstitution. Cell Adh Migr 2017; 10:475-494. [PMID: 27715396 PMCID: PMC5079405 DOI: 10.1080/19336918.2016.1241923] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Microtubules switch between growing and shrinking states, a feature known as dynamic instability. The biochemical parameters underlying dynamic instability are modulated by a wide variety of microtubule-associated proteins that enable the strict control of microtubule dynamics in cells. The forces generated by controlled growth and shrinkage of microtubules drive a large range of processes, including organelle positioning, mitotic spindle assembly, and chromosome segregation. In the past decade, our understanding of microtubule dynamics and microtubule force generation has progressed significantly. Here, we review the microtubule-intrinsic process of dynamic instability, the effect of external factors on this process, and how the resulting forces act on various biological systems. Recently, reconstitution-based approaches have strongly benefited from extensive biochemical and biophysical characterization of individual components that are involved in regulating or transmitting microtubule-driven forces. We will focus on the current state of reconstituting increasingly complex biological systems and provide new directions for future developments.
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Affiliation(s)
- Mathijs Vleugel
- a Department of Bionanoscience , Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft Institute of Technology , Delft , The Netherlands
| | - Maurits Kok
- a Department of Bionanoscience , Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft Institute of Technology , Delft , The Netherlands
| | - Marileen Dogterom
- a Department of Bionanoscience , Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft Institute of Technology , Delft , The Netherlands
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81
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Four-stranded mini microtubules formed by Prosthecobacter BtubAB show dynamic instability. Proc Natl Acad Sci U S A 2017; 114:E5950-E5958. [PMID: 28673988 DOI: 10.1073/pnas.1705062114] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Microtubules, the dynamic, yet stiff hollow tubes built from αβ-tubulin protein heterodimers, are thought to be present only in eukaryotic cells. Here, we report a 3.6-Å helical reconstruction electron cryomicroscopy structure of four-stranded mini microtubules formed by bacterial tubulin-like Prosthecobacter dejongeii BtubAB proteins. Despite their much smaller diameter, mini microtubules share many key structural features with eukaryotic microtubules, such as an M-loop, alternating subunits, and a seam that breaks overall helical symmetry. Using in vitro total internal reflection fluorescence microscopy, we show that bacterial mini microtubules treadmill and display dynamic instability, another hallmark of eukaryotic microtubules. The third protein in the btub gene cluster, BtubC, previously known as "bacterial kinesin light chain," binds along protofilaments every 8 nm, inhibits BtubAB mini microtubule catastrophe, and increases rescue. Our work reveals that some bacteria contain regulated and dynamic cytomotive microtubule systems that were once thought to be only useful in much larger and sophisticated eukaryotic cells.
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82
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Kinesin-5-independent mitotic spindle assembly requires the antiparallel microtubule crosslinker Ase1 in fission yeast. Nat Commun 2017; 8:15286. [PMID: 28513584 PMCID: PMC5442317 DOI: 10.1038/ncomms15286] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 03/13/2017] [Indexed: 12/04/2022] Open
Abstract
Bipolar spindle assembly requires a balance of forces where kinesin-5 produces outward pushing forces to antagonize the inward pulling forces from kinesin-14 or dynein. Accordingly, Kinesin-5 inactivation results in force imbalance leading to monopolar spindle and chromosome segregation failure. In fission yeast, force balance is restored when both kinesin-5 Cut7 and kinesin-14 Pkl1 are deleted, restoring spindle bipolarity. Here we show that the cut7Δpkl1Δ spindle is fully competent for chromosome segregation independently of motor activity, except for kinesin-6 Klp9, which is required for anaphase spindle elongation. We demonstrate that cut7Δpkl1Δ spindle bipolarity requires the microtubule antiparallel bundler PRC1/Ase1 to recruit CLASP/Cls1 to stabilize microtubules. Brownian dynamics-kinetic Monte Carlo simulations show that Ase1 and Cls1 activity are sufficient for initial bipolar spindle formation. We conclude that pushing forces generated by microtubule polymerization are sufficient to promote spindle pole separation and the assembly of bipolar spindle in the absence of molecular motors. Bipolar spindle assembly requires a balance of kinesin 14 pulling and kinesin 5 pushing forces. Here, the authors show that in fission yeast, spindle formation can occur in the absence of kinesin 5 (Cut7) and 14 (Pkl1) but requires the microtubule-associated protein Ase1 for spindle bipolarity.
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83
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Byrnes AE, Slep KC. TOG-tubulin binding specificity promotes microtubule dynamics and mitotic spindle formation. J Cell Biol 2017; 216:1641-1657. [PMID: 28512144 PMCID: PMC5461023 DOI: 10.1083/jcb.201610090] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 03/02/2017] [Accepted: 04/26/2017] [Indexed: 11/24/2022] Open
Abstract
Microtubule-associated proteins with arrays of TOG domains differentially regulate microtubule dynamics. Byrnes and Slep show that TOG arrays are polarized containing architecturally distinct TOG domains that bind either free or microtubule lattice-incorporated tubulin, which is essential for microtubule polymerization and mitotic spindle formation. XMAP215, CLASP, and Crescerin use arrayed tubulin-binding tumor overexpressed gene (TOG) domains to modulate microtubule dynamics. We hypothesized that TOGs have distinct architectures and tubulin-binding properties that underlie each family’s ability to promote microtubule polymerization or pause. As a model, we investigated the pentameric TOG array of a Drosophila melanogaster XMAP215 member, Msps. We found that Msps TOGs have distinct architectures that bind either free or polymerized tubulin, and that a polarized array drives microtubule polymerization. An engineered TOG1-2-5 array fully supported Msps-dependent microtubule polymerase activity. Requisite for this activity was a TOG5-specific N-terminal HEAT repeat that engaged microtubule lattice-incorporated tubulin. TOG5–microtubule binding maintained mitotic spindle formation as deleting or mutating TOG5 compromised spindle architecture and increased the mitotic index. Mad2 knockdown released the spindle assembly checkpoint triggered when TOG5–microtubule binding was compromised, indicating that TOG5 is essential for spindle function. Our results reveal a TOG5-specific role in mitotic fidelity and support our hypothesis that architecturally distinct TOGs arranged in a sequence-specific order underlie TOG array microtubule regulator activity.
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Affiliation(s)
- Amy E Byrnes
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599.,Program in Molecular and Cellular Biophysics, University of North Carolina, Chapel Hill, NC 27599
| | - Kevin C Slep
- Program in Molecular and Cellular Biophysics, University of North Carolina, Chapel Hill, NC 27599 .,Department of Biology, University of North Carolina, Chapel Hill, NC 27599
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84
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Dillon GM, Tyler WA, Omuro KC, Kambouris J, Tyminski C, Henry S, Haydar TF, Beffert U, Ho A. CLASP2 Links Reelin to the Cytoskeleton during Neocortical Development. Neuron 2017; 93:1344-1358.e5. [PMID: 28285824 PMCID: PMC5405870 DOI: 10.1016/j.neuron.2017.02.039] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 01/06/2017] [Accepted: 02/21/2017] [Indexed: 12/14/2022]
Abstract
The Reelin signaling pathway plays a crucial role in regulating neocortical development. However, little is known about how Reelin controls the cytoskeleton during neuronal migration. Here, we identify CLASP2 as a key cytoskeletal effector in the Reelin signaling pathway. We demonstrate that CLASP2 has distinct roles during neocortical development regulating neuron production and controlling neuron migration, polarity, and morphogenesis. We found downregulation of CLASP2 in migrating neurons leads to mislocalized cells in deeper cortical layers, abnormal positioning of the centrosome-Golgi complex, and aberrant length/orientation of the leading process. We discovered that Reelin regulates several phosphorylation sites within the positively charged serine/arginine-rich region that constitute consensus GSK3β phosphorylation motifs of CLASP2. Furthermore, phosphorylation of CLASP2 regulates its interaction with the Reelin adaptor Dab1 and this association is required for CLASP2 effects on neurite extension and motility. Together, our data reveal that CLASP2 is an essential Reelin effector orchestrating cytoskeleton dynamics during brain development.
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Affiliation(s)
- Gregory M Dillon
- Department of Biology, Boston University, 24 Cummington Mall, Boston, MA 02215, USA
| | - William A Tyler
- Department of Anatomy and Neurobiology, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, USA
| | - Kerilyn C Omuro
- Department of Biology, Boston University, 24 Cummington Mall, Boston, MA 02215, USA
| | - John Kambouris
- Department of Biology, Boston University, 24 Cummington Mall, Boston, MA 02215, USA
| | - Camila Tyminski
- Department of Biology, Boston University, 24 Cummington Mall, Boston, MA 02215, USA
| | - Shawna Henry
- Department of Biology, Boston University, 24 Cummington Mall, Boston, MA 02215, USA
| | - Tarik F Haydar
- Department of Anatomy and Neurobiology, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, USA
| | - Uwe Beffert
- Department of Biology, Boston University, 24 Cummington Mall, Boston, MA 02215, USA.
| | - Angela Ho
- Department of Biology, Boston University, 24 Cummington Mall, Boston, MA 02215, USA.
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85
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Nishita M, Satake T, Minami Y, Suzuki A. Regulatory mechanisms and cellular functions of non-centrosomal microtubules. J Biochem 2017; 162:1-10. [DOI: 10.1093/jb/mvx018] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 03/02/2017] [Indexed: 02/07/2023] Open
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86
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Portilho DM, Persson R, Arhel N. Role of non-motile microtubule-associated proteins in virus trafficking. Biomol Concepts 2017; 7:283-292. [PMID: 27879481 DOI: 10.1515/bmc-2016-0018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 11/04/2016] [Indexed: 11/15/2022] Open
Abstract
Viruses are entirely dependent on their ability to infect a host cell in order to replicate. To reach their site of replication as rapidly and efficiently as possible following cell entry, many have evolved elaborate mechanisms to hijack the cellular transport machinery to propel themselves across the cytoplasm. Long-range movements have been shown to involve motor proteins along microtubules (MTs) and direct interactions between viral proteins and dynein and/or kinesin motors have been well described. Although less well-characterized, it is also becoming increasingly clear that non-motile microtubule-associated proteins (MAPs), including structural MAPs of the MAP1 and MAP2 families, and microtubule plus-end tracking proteins (+TIPs), can also promote viral trafficking in infected cells, by mediating interaction of viruses with filaments and/or motor proteins, and modulating filament stability. Here we review our current knowledge on non-motile MAPs, their role in the regulation of cytoskeletal dynamics and in viral trafficking during the early steps of infection.
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87
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Mechanisms of Chromosome Congression during Mitosis. BIOLOGY 2017; 6:biology6010013. [PMID: 28218637 PMCID: PMC5372006 DOI: 10.3390/biology6010013] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 01/07/2017] [Accepted: 01/28/2017] [Indexed: 12/13/2022]
Abstract
Chromosome congression during prometaphase culminates with the establishment of a metaphase plate, a hallmark of mitosis in metazoans. Classical views resulting from more than 100 years of research on this topic have attempted to explain chromosome congression based on the balance between opposing pulling and/or pushing forces that reach an equilibrium near the spindle equator. However, in mammalian cells, chromosome bi-orientation and force balance at kinetochores are not required for chromosome congression, whereas the mechanisms of chromosome congression are not necessarily involved in the maintenance of chromosome alignment after congression. Thus, chromosome congression and maintenance of alignment are determined by different principles. Moreover, it is now clear that not all chromosomes use the same mechanism for congressing to the spindle equator. Those chromosomes that are favorably positioned between both poles when the nuclear envelope breaks down use the so-called "direct congression" pathway in which chromosomes align after bi-orientation and the establishment of end-on kinetochore-microtubule attachments. This favors the balanced action of kinetochore pulling forces and polar ejection forces along chromosome arms that drive chromosome oscillatory movements during and after congression. The other pathway, which we call "peripheral congression", is independent of end-on kinetochore microtubule-attachments and relies on the dominant and coordinated action of the kinetochore motors Dynein and Centromere Protein E (CENP-E) that mediate the lateral transport of peripheral chromosomes along microtubules, first towards the poles and subsequently towards the equator. How the opposite polarities of kinetochore motors are regulated in space and time to drive congression of peripheral chromosomes only now starts to be understood. This appears to be regulated by position-dependent phosphorylation of both Dynein and CENP-E and by spindle microtubule diversity by means of tubulin post-translational modifications. This so-called "tubulin code" might work as a navigation system that selectively guides kinetochore motors with opposite polarities along specific spindle microtubule populations, ultimately leading to the congression of peripheral chromosomes. We propose an integrated model of chromosome congression in mammalian cells that depends essentially on the following parameters: (1) chromosome position relative to the spindle poles after nuclear envelope breakdown; (2) establishment of stable end-on kinetochore-microtubule attachments and bi-orientation; (3) coordination between kinetochore- and arm-associated motors; and (4) spatial signatures associated with post-translational modifications of specific spindle microtubule populations. The physiological consequences of abnormal chromosome congression, as well as the therapeutic potential of inhibiting chromosome congression are also discussed.
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88
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de Forges H, Pilon A, Cantaloube I, Pallandre A, Haghiri-Gosnet AM, Perez F, Poüs C. Localized Mechanical Stress Promotes Microtubule Rescue. Curr Biol 2016; 26:3399-3406. [PMID: 27916523 DOI: 10.1016/j.cub.2016.10.048] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 07/12/2016] [Accepted: 10/26/2016] [Indexed: 11/19/2022]
Abstract
Microtubule dynamics rely on the properties of tubulin and are regulated by microtubule-associated proteins. GTP-tubulin assembles into hollow polymers, which can depolymerize upon GTP hydrolysis. Depolymerizing microtubules may stop shrinking and resume growth. Such rescues are regulated by microtubule-associated proteins like CLIP-170 and the CLASPs [1, 2]. Microtubule domains prone to rescues contain discrete regions (previously termed "GTP islands") that retain a GTP-tubulin-like conformation in the main body of the microtubule [3]. However, the exact nature of these domains and the mechanisms controlling their occurrence and distribution are largely unknown. Here we show that collisions between growing microtubules and mechanical obstacles (including other microtubules) in vitro result in the higher abundance of GTP-like islands in stressed microtubule regions. Furthermore, these islands were found to be efficiently generated by both lateral contacts and mechanical constraints applied to the main body of the microtubules. They were also particularly prominent where shifts in the number of protofilaments occur in the microtubule lattice. GTP-like islands and rescues frequently co-occurred at microtubule intersections in vitro and in living cells, both in crossing and in crossed microtubules. We also observed that CLIP-170 recognizes GTP-like islands in vivo and is retained at microtubule crossings. Therefore, we propose that rescues occur via a two-stage mechanism: (1) lattice defects determine potential rescue-promoting islands in the microtubule structure, and (2) CLIP-170 detects these islands to stimulate microtubule rescue. Our results reveal the interplay between rescue-promoting factors and microtubule architecture and organization to control microtubule dynamics.
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Affiliation(s)
- Hélène de Forges
- Institut Curie, PSL Research University, CNRS UMR 144, rue d'Ulm, 75246 Paris Cedex 05, France
| | - Antoine Pilon
- INSERM UMR-S 1193, Univ. Paris-Sud, Université Paris-Saclay, rue Jean-Baptiste Clément, 92296 Châtenay-Malabry, France; Biochimie, APHP, Hôpitaux Universitaires de l'Est Parisien, Site St Antoine, rue du Faubourg Saint Antoine, 75571 Paris Cedex 12, France
| | - Isabelle Cantaloube
- INSERM UMR-S 1193, Univ. Paris-Sud, Université Paris-Saclay, rue Jean-Baptiste Clément, 92296 Châtenay-Malabry, France
| | - Antoine Pallandre
- CNRS UPR 20, Laboratoire de Photonique et Nanostructures, route de Nozay, F-91460 Marcoussis, France; Univ. Paris-Sud, Université Paris-Saclay, Faculté de Pharmacie, rue Jean-Baptiste Clément, 92296 Châtenay-Malabry, France
| | - Anne-Marie Haghiri-Gosnet
- CNRS UPR 20, Laboratoire de Photonique et Nanostructures, route de Nozay, F-91460 Marcoussis, France
| | - Franck Perez
- Institut Curie, PSL Research University, CNRS UMR 144, rue d'Ulm, 75246 Paris Cedex 05, France.
| | - Christian Poüs
- INSERM UMR-S 1193, Univ. Paris-Sud, Université Paris-Saclay, rue Jean-Baptiste Clément, 92296 Châtenay-Malabry, France; Biochimie-Hormonologie, APHP, Hôpitaux Universitaires Paris-Sud, Site Antoine Béclère, rue de la Porte de Trivaux, 92141 Clamart, France.
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89
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Moriwaki T, Goshima G. Five factors can reconstitute all three phases of microtubule polymerization dynamics. J Cell Biol 2016; 215:357-368. [PMID: 27799364 PMCID: PMC5100292 DOI: 10.1083/jcb.201604118] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 09/23/2016] [Indexed: 12/15/2022] Open
Abstract
Cytoplasmic microtubules (MTs) undergo growth, shrinkage, and pausing. However, how MT polymerization cycles are produced and spatiotemporally regulated at a molecular level is unclear, as the entire cycle has not been recapitulated in vitro with defined components. In this study, we reconstituted dynamic MT plus end behavior involving all three phases by mixing tubulin with five Drosophila melanogaster proteins (EB1, XMAP215Msps, Sentin, kinesin-13Klp10A, and CLASPMast/Orbit). When singly mixed with tubulin, CLASPMast/Orbit strongly inhibited MT catastrophe and reduced the growth rate. However, in the presence of the other four factors, CLASPMast/Orbit acted as an inducer of pausing. The mitotic kinase Plk1Polo modulated the activity of CLASPMast/Orbit and kinesin-13Klp10A and increased the dynamic instability of MTs, reminiscent of mitotic cells. These results suggest that five conserved proteins constitute the core factors for creating dynamic MTs in cells and that Plk1-dependent phosphorylation is a crucial event for switching from the interphase to mitotic mode.
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Affiliation(s)
- Takashi Moriwaki
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
- Marine Biological Laboratory, Woods Hole, MA 02543
| | - Gohta Goshima
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
- Marine Biological Laboratory, Woods Hole, MA 02543
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90
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Bailey ME, Sackett DL, Ross JL. Katanin Severing and Binding Microtubules Are Inhibited by Tubulin Carboxy Tails. Biophys J 2016; 109:2546-2561. [PMID: 26682813 DOI: 10.1016/j.bpj.2015.11.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 10/30/2015] [Accepted: 11/04/2015] [Indexed: 10/22/2022] Open
Abstract
Microtubule dynamics in cells are regulated by associated proteins that can be either stabilizers or destabilizers. A class of destabilizers that is important in a large number of cellular activities is the microtubule-severing enzymes, yet little is known about how they function. Katanin p60 was the first ATPase associated with microtubule severing. Here, we investigate the activity of katanin severing using a GFP-labeled human version. We quantify the effect of katanin concentration on katanin binding and severing activity. We find that free tubulin can inhibit severing activity by interfering with katanin binding to microtubules. The inhibition is mediated by the sequence of the tubulin and specifically depends on the carboxy-terminal tails. We directly investigate the inhibition effect of tubulin carboxy-terminal tails using peptide sequences of α-, β-, or detyrosinated α-tubulin tails that have been covalently linked to bovine serum albumin. Our results show that β-tubulin tails are the most effective at inhibiting severing, and that detyrosinated α-tubulin tails are the least effective. These results are distinct from those for other severing enzymes and suggest a scheme for regulation of katanin activity in cells dependent on free tubulin concentration and the modification state of the tubulin.
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Affiliation(s)
- Megan E Bailey
- Molecular and Cellular Biology Graduate Program, University of Massachusetts-Amherst, Amherst, Massachusetts; Department of Physics, University of Massachusetts-Amherst, Amherst, Massachusetts
| | - Dan L Sackett
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
| | - Jennifer L Ross
- Department of Physics, University of Massachusetts-Amherst, Amherst, Massachusetts.
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91
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Bowne-Anderson H, Hibbel A, Howard J. Regulation of Microtubule Growth and Catastrophe: Unifying Theory and Experiment. Trends Cell Biol 2016; 25:769-779. [PMID: 26616192 DOI: 10.1016/j.tcb.2015.08.009] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 08/27/2015] [Accepted: 08/27/2015] [Indexed: 10/22/2022]
Abstract
Recent studies have found that microtubule-associated proteins (MAPs) can regulate the dynamical properties of microtubules in unexpected ways. For most MAPs, there is an inverse relationship between their effects on the speed of growth and the frequency of catastrophe, the conversion of a growing microtubule to a shrinking one. Such a negative correlation is predicted by the standard GTP-cap model, which posits that catastrophe is due to loss of a stabilizing cap of GTP-tubulin at the end of a growing microtubule. However, many other MAPs, notably Kinesin-4 and combinations of EB1 with XMAP215, contradict this general rule. In this review, we show that a more nuanced, but still simple, GTP-cap model, can account for the diverse regulatory activities of MAPs.
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Affiliation(s)
| | - Anneke Hibbel
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany; ETH Zurich, Institute for Biochemistry, HPM E8.1, Otto-Stern-Weg 3, 8093 Zurich, Switzerland
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92
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Abstract
The dynamic instability of microtubules is characterised by slow growth phases stochastically interrupted by rapid depolymerisations called catastrophes. Rescue events can arrest the depolymerisation and restore microtubule elongation. However the origin of these rescue events remain unexplained. Here we show that microtubule lattice self-repair, in structurally damaged sites, is responsible for the rescue of microtubule growth. Tubulin photo-conversion in cells revealed that free tubulin dimers can incorporate along the shafts of microtubules, especially in regions where microtubules cross each other, form bundles or become bent due to mechanical constraints. These incorporation sites appeared to act as effective rescue sites ensuring microtubule rejuvenation. By securing damaged microtubule growth, the self-repair process supports a mechanosensitive growth by specifically promoting microtubule assembly in regions where they are subjected to physical constraints.
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93
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Voelzmann A, Hahn I, Pearce SP, Sánchez-Soriano N, Prokop A. A conceptual view at microtubule plus end dynamics in neuronal axons. Brain Res Bull 2016; 126:226-237. [PMID: 27530065 PMCID: PMC5090033 DOI: 10.1016/j.brainresbull.2016.08.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 08/08/2016] [Accepted: 08/11/2016] [Indexed: 12/02/2022]
Abstract
Axons are the cable-like protrusions of neurons which wire up the nervous system. Polar bundles of microtubules (MTs) constitute their structural backbones and are highways for life-sustaining transport between proximal cell bodies and distal synapses. Any morphogenetic changes of axons during development, plastic rearrangement, regeneration or degeneration depend on dynamic changes of these MT bundles. A key mechanism for implementing such changes is the coordinated polymerisation and depolymerisation at the plus ends of MTs within these bundles. To gain an understanding of how such regulation can be achieved at the cellular level, we provide here an integrated overview of the extensive knowledge we have about the molecular mechanisms regulating MT de/polymerisation. We first summarise insights gained from work in vitro, then describe the machinery which supplies the essential tubulin building blocks, the protein complexes associating with MT plus ends, and MT shaft-based mechanisms that influence plus end dynamics. We briefly summarise the contribution of MT plus end dynamics to important cellular functions in axons, and conclude by discussing the challenges and potential strategies of integrating the existing molecular knowledge into conceptual understanding at the level of axons.
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Affiliation(s)
- André Voelzmann
- The University of Manchester, Faculty of Biology, Medicine and Health, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Ines Hahn
- The University of Manchester, Faculty of Biology, Medicine and Health, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Simon P Pearce
- The University of Manchester, Faculty of Biology, Medicine and Health, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK; The University of Manchester, School of Mathematics, Alan Turing Building, Oxford Road, Manchester M13 9PL, UK
| | - Natalia Sánchez-Soriano
- University of Liverpool, Institute of Translational Medicine, Department of Cellular and Molecular Physiology, Crown Street, Liverpool, L69 3BX, UK
| | - Andreas Prokop
- The University of Manchester, Faculty of Biology, Medicine and Health, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK.
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94
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Kent IA, Lele TP. Microtubule-based force generation. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2016; 9. [PMID: 27562344 DOI: 10.1002/wnan.1428] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 07/20/2016] [Accepted: 07/30/2016] [Indexed: 11/11/2022]
Abstract
Microtubules are vital to many important cell processes, such as cell division, transport of cellular cargo, organelle positioning, and cell migration. Owing to their diverse functions, understanding microtubule function is an important part of cell biological research that can help in combating various diseases. For example, microtubules are an important target of chemotherapeutic drugs such as paclitaxel because of their pivotal role in cell division. Many functions of microtubules relate to the generation of mechanical forces. These forces are generally either a direct result of microtubule polymerization/depolymerization or generated by motor proteins that move processively along microtubules. In this review, we summarize recent efforts to quantify and model force generation by microtubules in the context of microtubule function. WIREs Nanomed Nanobiotechnol 2017, 9:e1428. doi: 10.1002/wnan.1428 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Ian A Kent
- Department of Chemical Engineering, University of Florida, Gainesville, FL, USA
| | - Tanmay P Lele
- Department of Chemical Engineering, University of Florida, Gainesville, FL, USA
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95
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Isolation of Functional Tubulin Dimers and of Tubulin-Associated Proteins from Mammalian Cells. Curr Biol 2016; 26:1728-1736. [DOI: 10.1016/j.cub.2016.04.069] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 03/15/2016] [Accepted: 04/26/2016] [Indexed: 11/18/2022]
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96
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Zhu X, Efimova N, Arnette C, Hanks SK, Kaverina I. Podosome dynamics and location in vascular smooth muscle cells require CLASP-dependent microtubule bending. Cytoskeleton (Hoboken) 2016; 73:300-15. [PMID: 27105779 DOI: 10.1002/cm.21302] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 04/15/2016] [Accepted: 04/20/2016] [Indexed: 11/07/2022]
Abstract
Extracellular matrix (ECM) remodeling during physiological processes is mediated by invasive protrusions called podosomes. Positioning and dynamics of podosomes define the extent of ECM degradation. Microtubules are known to be involved in podosome regulation, but the role of microtubule (MT) network configuration in podosome dynamics and positioning is not well understood. Here, we show that the arrangement of the microtubule network defines the pattern of podosome formation and relocation in vascular smooth muscle cells (VSMCs). We show that microtubule plus-end targeting facilitates de novo formation of podosomes, in addition to podosome remodeling. Moreover, specialized bent microtubules with plus ends reversed towards the cell center promote relocation of podosomes from the cell edge to the cell center, resulting in an evenly distributed podosome pattern. Microtubule bending is induced downstream of protein kinase C (PKC) activation and requires microtubule-stabilizing proteins known as cytoplasmic linker associated proteins (CLASPs) and retrograde actin flow. Similar to microtubule depolymerization, CLASP depletion by siRNA blocks microtubule bending and eliminates centripetal relocation of podosomes. Podosome relocation also coincides with translocation of podosome-stimulating kinesin KIF1C, which is known to move preferentially along CLASP-associated microtubules. These findings indicate that CLASP-dependent microtubule network configuration is critical to the cellular location and distribution of KIF1C-dependent podosomes. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Xiaodong Zhu
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN
| | - Nadia Efimova
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN
| | - Christopher Arnette
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN
| | - Steven K Hanks
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN
| | - Irina Kaverina
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN
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97
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Grimaldi AD, Zanic M, Kaverina I. Encoding the microtubule structure: Allosteric interactions between the microtubule +TIP complex master regulators and TOG-domain proteins. Cell Cycle 2016; 14:1375-8. [PMID: 25895033 DOI: 10.1080/15384101.2015.1026521] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Since their initial discovery, the intriguing proteins of the +TIP network have been the focus of intense investigation. Although many of the individual +TIP functions have been revealed, the capacity for +TIP proteins to regulate each other has not been widely addressed. Importantly, recent studies involving EBs, the master regulators of the +TIP complex, and several TOG-domain proteins have uncovered a novel mechanism of mutual +TIP regulation: allosteric interactions through changes in microtubule structure. These findings have added another level of complexity to the existing evidence on +TIP regulation and highlight the cooperative nature of the +TIP protein network.
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Affiliation(s)
- Ashley D Grimaldi
- a Department of Cell and Developmental Biology ; Vanderbilt University Medical Center ; Nashville , TN USA
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98
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Chi Z, Ambrose C. Microtubule encounter-based catastrophe in Arabidopsis cortical microtubule arrays. BMC PLANT BIOLOGY 2016; 16:18. [PMID: 26774503 PMCID: PMC4715342 DOI: 10.1186/s12870-016-0703-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 01/06/2016] [Indexed: 05/11/2023]
Abstract
BACKGROUND The cortical microtubules (CMTs) that line the plasma membrane of interphase plant cells are extensively studied owing to their importance in forming cell walls, and their usefulness as a model system for the study of MT dynamic instability and acentrosomal MT organization. CMTs influence the orientation and structure of cellulose microfibrils in the cell wall by cooperatively forming arrays of varied patterns from parallel to netted. These CMT patterns are controlled by the combined activities of MT dynamic instability and MT-MT interactions. However, it is an open question as to how CMT patterns may feedback to influence CMT dynamics and interactions. RESULTS To address this question, we investigated the effects of CMT array patterning on encounter-based CMT catastrophe, which occurs when one CMT grows into another and is unable to cross over. We hypothesized that the varied CMT angles present in disordered (mixed CMTs) arrays will create more opportunities for MT-MT interactions, and thus increase encounter-based catastrophe rates and distribution. Using live-cell imaging of Arabidopsis cotyledon and leaf epidermal cells, we found that roughly 87% of catastrophes occur via the encounter-based mechanism, with the remainder occurring without encounter (free). When comparing ordered (parallel) and disordered (mixed orientation) CMT arrays, we found that disordered configurations show higher proportions of encounter-based catastrophe relative to free. Similarly, disordered CMT arrays have more catastrophes in general than ordered arrays. Encounter-based catastrophes were associated with frequent and sustained periods of pause prior to depolymerization, and CMTs with tight anchoring to the plasma membrane were more prone to undergo encounter-based catastrophe than weakly-attached ones. This suggests that encounter-based catastrophe has a mechanical basis, wherein MTs form physical barriers to one another. Lastly, we show that the commonly used measure of catastrophe frequencies (Fcat) can also be influenced by CMT ordering and plasma membrane anchoring. CONCLUSIONS Our observations add a new layer of complexity to our current understanding of MT organization in plants, showing that not only do individual CMT dynamics influence CMT array organization, but that CMT organization itself has a strong effect on the behavior of individual MTs.
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Affiliation(s)
- Zhihai Chi
- Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada.
| | - Chris Ambrose
- Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada.
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99
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Menon S, Gupton SL. Building Blocks of Functioning Brain: Cytoskeletal Dynamics in Neuronal Development. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 322:183-245. [PMID: 26940519 PMCID: PMC4809367 DOI: 10.1016/bs.ircmb.2015.10.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neural connectivity requires proper polarization of neurons, guidance to appropriate target locations, and establishment of synaptic connections. From when neurons are born to when they finally reach their synaptic partners, neurons undergo constant rearrangment of the cytoskeleton to achieve appropriate shape and polarity. Of particular importance to neuronal guidance to target locations is the growth cone at the tip of the axon. Growth-cone steering is also dictated by the underlying cytoskeleton. All these changes require spatiotemporal control of the cytoskeletal machinery. This review summarizes the proteins that are involved in modulating the actin and microtubule cytoskeleton during the various stages of neuronal development.
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Affiliation(s)
- Shalini Menon
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC, United States of America
| | - Stephanie L Gupton
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC, United States of America; Neuroscience Center and Curriculum in Neurobiology, University of North Carolina, Chapel Hill, NC, United States of America; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, United States of America.
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100
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Nogueira AT, Pedrosa AT, Carabeo RA. Manipulation of the Host Cell Cytoskeleton by Chlamydia. Curr Top Microbiol Immunol 2016; 412:59-80. [PMID: 27197645 DOI: 10.1007/82_2016_10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Chlamydiae are obligate intracellular pathogens. They undergo a biphasic developmental cycle differentiating between the infectious but metabolically quiescent elementary body and the vegetative, but non-infectious reticulate body. Chlamydia spends a significant portion of its development in the non-infectious stage, demanding an effective strategy of manipulating the host cells to ensure its intracellular survival and replication. A common target of all Chlamydia species studied so far is the host cell cytoskeleton, with past and recent findings revealing crucial roles in invasion, inclusion maintenance, nutrient acquisition, and egress. The molecular details of how Chlamydia co-opts the cytoskeleton is becoming clearer, with bacterial factors and their corresponding host cell targets identified.
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Affiliation(s)
- Ana T Nogueira
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USA
| | - Antonio T Pedrosa
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USA
| | - Rey A Carabeo
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USA.
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