1
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Paim LMG, Lopez-Jauregui AA, McAlear TS, Bechstedt S. The spindle protein CKAP2 regulates microtubule dynamics and ensures faithful chromosome segregation. Proc Natl Acad Sci U S A 2024; 121:e2318782121. [PMID: 38381793 PMCID: PMC10907244 DOI: 10.1073/pnas.2318782121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 12/28/2023] [Indexed: 02/23/2024] Open
Abstract
Regulation of microtubule dynamics by microtubule-associated proteins (MAPs) is essential for mitotic spindle assembly and chromosome segregation. Altered microtubule dynamics, particularly increased microtubule growth rates, were found to be a contributing factor for the development of chromosomal instability, which potentiates tumorigenesis. The MAP XMAP215/CKAP5 is the only known microtubule growth factor, and whether other MAPs regulate microtubule growth in cells is unclear. Our recent in vitro reconstitution experiments have demonstrated that Cytoskeleton-Associated Protein 2 (CKAP2) increases microtubule nucleation and growth rates, and here, we find that CKAP2 is also an essential microtubule growth factor in cells. By applying CRISPR-Cas9 knock-in and knock-out (KO) as well as microtubule plus-end tracking live cell imaging, we show that CKAP2 is a mitotic spindle protein that ensures faithful chromosome segregation by regulating microtubule growth. Live cell imaging of endogenously labeled CKAP2 showed that it localizes to the spindle during mitosis and rapidly shifts its localization to the chromatin upon mitotic exit before being degraded. Cells lacking CKAP2 display reduced microtubule growth rates and an increased proportion of chromosome segregation errors and aneuploidy that may be a result of an accumulation of kinetochore-microtubule misattachments. Microtubule growth rates and chromosome segregation fidelity can be rescued upon ectopic CKAP2 expression in KO cells, revealing a direct link between CKAP2 expression and microtubule dynamics. Our results unveil a role of CKAP2 in regulating microtubule growth in cells and provide a mechanistic explanation for the oncogenic potential of CKAP2 misregulation.
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Affiliation(s)
- Lia Mara Gomes Paim
- Department of Anatomy and Cell Biology, McGill University, Montréal, QCH3A 0C7, Canada
| | | | - Thomas S. McAlear
- Department of Anatomy and Cell Biology, McGill University, Montréal, QCH3A 0C7, Canada
| | - Susanne Bechstedt
- Department of Anatomy and Cell Biology, McGill University, Montréal, QCH3A 0C7, Canada
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2
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Zhu Z, Becam I, Tovey CA, Elfarkouchi A, Yen EC, Bernard F, Guichet A, Conduit PT. Multifaceted modes of γ-tubulin complex recruitment and microtubule nucleation at mitotic centrosomes. J Cell Biol 2023; 222:e202212043. [PMID: 37698931 PMCID: PMC10497398 DOI: 10.1083/jcb.202212043] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 05/18/2023] [Accepted: 07/24/2023] [Indexed: 09/14/2023] Open
Abstract
Microtubule nucleation is mediated by γ-tubulin ring complexes (γ-TuRCs). In most eukaryotes, a GCP4/5/4/6 "core" complex promotes γ-tubulin small complex (γ-TuSC) association to generate cytosolic γ-TuRCs. Unlike γ-TuSCs, however, this core complex is non-essential in various species and absent from budding yeasts. In Drosophila, Spindle defective-2 (Spd-2) and Centrosomin (Cnn) redundantly recruit γ-tubulin complexes to mitotic centrosomes. Here, we show that Spd-2 recruits γ-TuRCs formed via the GCP4/5/4/6 core, but Cnn can recruit γ-TuSCs directly via its well-conserved CM1 domain, similar to its homologs in budding yeast. When centrosomes fail to recruit γ-tubulin complexes, they still nucleate microtubules via the TOG domain protein Mini-spindles (Msps), but these microtubules have different dynamic properties. Our data, therefore, help explain the dispensability of the GCP4/5/4/6 core and highlight the robustness of centrosomes as microtubule organizing centers. They also suggest that the dynamic properties of microtubules are influenced by how they are nucleated.
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Affiliation(s)
- Zihan Zhu
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Isabelle Becam
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Corinne A. Tovey
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Abir Elfarkouchi
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Eugenie C. Yen
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Fred Bernard
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Antoine Guichet
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Paul T. Conduit
- Department of Zoology, University of Cambridge, Cambridge, UK
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
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3
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Lu W, Lakonishok M, Gelfand VI. The dynamic duo of microtubule polymerase Mini spindles/XMAP215 and cytoplasmic dynein is essential for maintaining Drosophila oocyte fate. Proc Natl Acad Sci U S A 2023; 120:e2303376120. [PMID: 37722034 PMCID: PMC10523470 DOI: 10.1073/pnas.2303376120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 07/11/2023] [Indexed: 09/20/2023] Open
Abstract
In many species, only one oocyte is specified among a group of interconnected germline sister cells. In Drosophila melanogaster, 16 interconnected cells form a germline cyst, where one cell differentiates into an oocyte, while the rest become nurse cells that supply the oocyte with mRNAs, proteins, and organelles through intercellular cytoplasmic bridges named ring canals via microtubule-based transport. In this study, we find that a microtubule polymerase Mini spindles (Msps), the Drosophila homolog of XMAP215, is essential for maintenance of the oocyte specification. mRNA encoding Msps is transported and concentrated in the oocyte by dynein-dependent transport along microtubules. Translated Msps stimulates microtubule polymerization in the oocyte, causing more microtubule plus ends to grow from the oocyte through the ring canals into nurse cells, further enhancing nurse cell-to-oocyte transport by dynein. Knockdown of msps blocks the oocyte growth and causes gradual loss of oocyte determinants. Thus, the Msps-dynein duo creates a positive feedback loop, ensuring oocyte fate maintenance by promoting high microtubule polymerization activity in the oocyte, and enhancing dynein-dependent nurse cell-to-oocyte transport.
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Affiliation(s)
- Wen Lu
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
| | - Margot Lakonishok
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
| | - Vladimir I. Gelfand
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
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4
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Zhu B, Jin P, Zhang Y, Shen Y, Wang W, Li S. Genomic and transcriptomic analyses support a silk gland origin of spider venom glands. BMC Biol 2023; 21:82. [PMID: 37055766 PMCID: PMC10099834 DOI: 10.1186/s12915-023-01581-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/29/2023] [Indexed: 04/15/2023] Open
Abstract
BACKGROUND Spiders comprise a hyperdiverse lineage of predators with venom systems, yet the origin of functionally novel spider venom glands remains unclear. Previous studies have hypothesized that spider venom glands originated from salivary glands or evolved from silk-producing glands present in early chelicerates. However, there is insufficient molecular evidence to indicate similarity among them. Here, we provide comparative analyses of genome and transcriptome data from various lineages of spiders and other arthropods to advance our understanding of spider venom gland evolution. RESULTS We generated a chromosome-level genome assembly of a model spider species, the common house spider (Parasteatoda tepidariorum). Module preservation, GO semantic similarity, and differentially upregulated gene similarity analyses demonstrated a lower similarity in gene expressions between the venom glands and salivary glands compared to the silk glands, which questions the validity of the salivary gland origin hypothesis but unexpectedly prefers to support the ancestral silk gland origin hypothesis. The conserved core network in the venom and silk glands was mainly correlated with transcription regulation, protein modification, transport, and signal transduction pathways. At the genetic level, we found that many genes in the venom gland-specific transcription modules show positive selection and upregulated expressions, suggesting that genetic variation plays an important role in the evolution of venom glands. CONCLUSIONS This research implies the unique origin and evolutionary path of spider venom glands and provides a basis for understanding the diverse molecular characteristics of venom systems.
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Affiliation(s)
- Bingyue Zhu
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 101408, China
| | - Pengyu Jin
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yiming Zhang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 101408, China
| | - Yunxiao Shen
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 101408, China
| | - Wei Wang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- Key Laboratory of Ecology and Environmental Protection of Rare and Endangered Animals and Plants, Ministry of Education, Guangxi Normal University, Guilin, 541004, China
| | - Shuqiang Li
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
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5
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Vaikakkara Chithran A, Allan DW, O'Connor TP. Adult expression of Semaphorins and Plexins is essential for motor neuron survival. Sci Rep 2023; 13:5894. [PMID: 37041188 PMCID: PMC10090137 DOI: 10.1038/s41598-023-32943-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 04/05/2023] [Indexed: 04/13/2023] Open
Abstract
Axon guidance cues direct the growth and steering of neuronal growth cones, thus guiding the axons to their targets during development. Nonetheless, after axons have reached their targets and established functional circuits, many mature neurons continue to express these developmental cues. The role of axon guidance cues in the adult nervous system has not been fully elucidated. Using the expression pattern data available on FlyBase, we found that more than 96% of the guidance genes that are expressed in the Drosophila melanogaster embryo continue to be expressed in adults. We utilized the GeneSwitch and TARGET systems to spatiotemporally knockdown the expression of these guidance genes selectively in the adult neurons, once the development was completed. We performed an RNA interference (RNAi) screen against 44 guidance genes in the adult Drosophila nervous system and identified 14 genes that are required for adult survival and normal motility. Additionally, we show that adult expression of Semaphorins and Plexins in motor neurons is necessary for neuronal survival, indicating that guidance genes have critical functions in the mature nervous system.
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Affiliation(s)
- Aarya Vaikakkara Chithran
- Graduate Program in Neuroscience, University of British Columbia, 3402-2215 Wesbrook Mall, Vancouver, BC, V6T 1Z3, Canada
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Douglas W Allan
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Timothy P O'Connor
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC, V6T 1Z3, Canada.
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6
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Lu W, Lakonishok M, Gelfand VI. Drosophila oocyte specification is maintained by the dynamic duo of microtubule polymerase Mini spindles/XMAP215 and dynein. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.09.531953. [PMID: 36945460 PMCID: PMC10028982 DOI: 10.1101/2023.03.09.531953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
In many species, only one oocyte is specified among a group of interconnected germline sister cells. In Drosophila melanogaster , 16-cell interconnected cells form a germline cyst, where one cell differentiates into an oocyte, while the rest become nurse cells that supply the oocyte with mRNAs, proteins, and organelles through intercellular cytoplasmic bridges named ring canals via microtubule-based transport. In this study, we find that a microtubule polymerase Mini spindles (Msps), the Drosophila homolog of XMAP215, is essential for the oocyte fate determination. mRNA encoding Msps is concentrated in the oocyte by dynein-dependent transport along microtubules. Translated Msps stimulates microtubule polymerization in the oocyte, causing more microtubule plus ends to grow from the oocyte through the ring canals into nurse cells, further enhancing nurse cell-to-oocyte transport by dynein. Knockdown of msps blocks the oocyte growth and causes gradual loss of oocyte determinants. Thus, the Msps-dynein duo creates a positive feedback loop, enhancing dynein-dependent nurse cell-to-oocyte transport and transforming a small stochastic difference in microtubule polarity among sister cells into a clear oocyte fate determination. Significance statement Oocyte determination in Drosophila melanogaster provides a valuable model for studying cell fate specification. We describe the crucial role of the duo of microtubule polymerase Mini spindles (Msps) and cytoplasmic dynein in this process. We show that Msps is essential for oocyte fate determination. Msps concentration in the oocyte is achieved through dynein-dependent transport of msps mRNA along microtubules. Translated Msps stimulates microtubule polymerization in the oocyte, further enhancing nurse cell-to-oocyte transport by dynein. This creates a positive feedback loop that transforms a small stochastic difference in microtubule polarity among sister cells into a clear oocyte fate determination. Our findings provide important insights into the mechanisms of oocyte specification and have implications for understanding the development of multicellular organisms.
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Affiliation(s)
- Wen Lu
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Margot Lakonishok
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Vladimir I Gelfand
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
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7
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Farmer VJ, Zanic M. Beyond the GTP-cap: Elucidating the molecular mechanisms of microtubule catastrophe. Bioessays 2023; 45:e2200081. [PMID: 36398561 PMCID: PMC10648283 DOI: 10.1002/bies.202200081] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 11/03/2022] [Accepted: 11/04/2022] [Indexed: 11/19/2022]
Abstract
Almost 40 years since the discovery of microtubule dynamic instability, the molecular mechanisms underlying microtubule dynamics remain an area of intense research interest. The "standard model" of microtubule dynamics implicates a "cap" of GTP-bound tubulin dimers at the growing microtubule end as the main determinant of microtubule stability. Loss of the GTP-cap leads to microtubule "catastrophe," a switch-like transition from microtubule growth to shrinkage. However, recent studies, using biochemical in vitro reconstitution, cryo-EM, and computational modeling approaches, challenge the simple GTP-cap model. Instead, a new perspective on the mechanisms of microtubule dynamics is emerging. In this view, highly dynamic transitions between different structural conformations of the growing microtubule end - which may or may not be directly linked to the nucleotide content at the microtubule end - ultimately drive microtubule catastrophe.
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Affiliation(s)
- Veronica J. Farmer
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Marija Zanic
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
- Department of Biomolecular and Chemical Engineering, Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
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8
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Cushion TD, Leca I, Keays DA. MAPping tubulin mutations. Front Cell Dev Biol 2023; 11:1136699. [PMID: 36875768 PMCID: PMC9975266 DOI: 10.3389/fcell.2023.1136699] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 02/02/2023] [Indexed: 02/17/2023] Open
Abstract
Microtubules are filamentous structures that play a critical role in a diverse array of cellular functions including, mitosis, nuclear translocation, trafficking of organelles and cell shape. They are composed of α/β-tubulin heterodimers which are encoded by a large multigene family that has been implicated in an umbrella of disease states collectively known as the tubulinopathies. De novo mutations in different tubulin genes are known to cause lissencephaly, microcephaly, polymicrogyria, motor neuron disease, and female infertility. The diverse clinical features associated with these maladies have been attributed to the expression pattern of individual tubulin genes, as well as their distinct Functional repertoire. Recent studies, however, have highlighted the impact of tubulin mutations on microtubule-associated proteins (MAPs). MAPs can be classified according to their effect on microtubules and include polymer stabilizers (e.g., tau, MAP2, doublecortin), destabilizers (e.g., spastin, katanin), plus-end binding proteins (e.g., EB1-3, XMAP215, CLASPs) and motor proteins (e.g., dyneins, kinesins). In this review we analyse mutation-specific disease mechanisms that influence MAP binding and their phenotypic consequences, and discuss methods by which we can exploit genetic variation to identify novel MAPs.
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Affiliation(s)
- Thomas D Cushion
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom.,Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Ines Leca
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - David A Keays
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom.,Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria.,Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University Munich, Munich, Germany
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9
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Vazquez-Pianzola P, Beuchle D, Saro G, Hernández G, Maldonado G, Brunßen D, Meister P, Suter B. Female meiosis II and pronuclear fusion require the microtubule transport factor Bicaudal D. Development 2022; 149:275749. [DOI: 10.1242/dev.199944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 05/25/2022] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Bicaudal D (BicD) is a dynein adaptor that transports different cargoes along microtubules. Reducing the activity of BicD specifically in freshly laid Drosophila eggs by acute protein degradation revealed that BicD is needed to produce normal female meiosis II products, to prevent female meiotic products from re-entering the cell cycle, and for pronuclear fusion. Given that BicD is required to localize the spindle assembly checkpoint (SAC) components Mad2 and BubR1 to the female meiotic products, it appears that BicD functions to localize these components to control metaphase arrest of polar bodies. BicD interacts with Clathrin heavy chain (Chc), and both proteins localize to centrosomes, mitotic spindles and the tandem spindles during female meiosis II. Furthermore, BicD is required to localize clathrin and the microtubule-stabilizing factors transforming acidic coiled-coil protein (D-TACC/Tacc) and Mini spindles (Msps) correctly to the meiosis II spindles, suggesting that failure to localize these proteins may perturb SAC function. Furthermore, immediately after the establishment of the female pronucleus, D-TACC and Caenorhabditis elegans BicD, tacc and Chc are also needed for pronuclear fusion, suggesting that the underlying mechanism might be more widely used across species.
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Affiliation(s)
| | - Dirk Beuchle
- Institute of Cell Biology, University of Bern 1 , 3012 Berne , Switzerland
| | - Gabriella Saro
- Institute of Cell Biology, University of Bern 1 , 3012 Berne , Switzerland
| | - Greco Hernández
- Instituto Nacional de Cancerología (INCan) 2 Laboratory of Translation and Cancer, Unit of Biomedical Research on Cancer , , 14080-Tlalpan, Mexico City , Mexico
| | - Giovanna Maldonado
- Instituto Nacional de Cancerología (INCan) 2 Laboratory of Translation and Cancer, Unit of Biomedical Research on Cancer , , 14080-Tlalpan, Mexico City , Mexico
| | - Dominique Brunßen
- Institute of Cell Biology, University of Bern 1 , 3012 Berne , Switzerland
| | - Peter Meister
- Institute of Cell Biology, University of Bern 1 , 3012 Berne , Switzerland
| | - Beat Suter
- Institute of Cell Biology, University of Bern 1 , 3012 Berne , Switzerland
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10
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Thomas A, Gallaud E, Pascal A, Serre L, Arnal I, Richard-Parpaillon L, Savoian MS, Giet R. Peripheral astral microtubules ensure asymmetric furrow positioning in neural stem cells. Cell Rep 2021; 37:109895. [PMID: 34706235 DOI: 10.1016/j.celrep.2021.109895] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 02/26/2021] [Accepted: 10/06/2021] [Indexed: 11/18/2022] Open
Abstract
Neuroblast division is characterized by asymmetric positioning of the cleavage furrow, resulting in a large difference in size between the future daughter cells. In animal cells, furrow placement and assembly are governed by centralspindlin that accumulates at the equatorial cell cortex of the future cleavage site and at the spindle midzone. In neuroblasts, these two centralspindlin populations are spatially and temporally separated. A leading pool is located at the basal cleavage site and a second pool accumulates at the midzone before traveling to the cleavage site. The cortical centralspindlin population requires peripheral astral microtubules and the chromosome passenger complex for efficient recruitment. Loss of this pool does not prevent cytokinesis but enhances centralspindlin signaling at the midzone, leading to equatorial furrow repositioning and decreased size asymmetry. These data show that basal furrow positioning in neuroblasts results from a competition between different centralspindlin pools in which the cortical pool is dominant.
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Affiliation(s)
- Alexandre Thomas
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR17 6290, 35000 Rennes, France
| | - Emmanuel Gallaud
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR17 6290, 35000 Rennes, France
| | - Aude Pascal
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR17 6290, 35000 Rennes, France
| | - Laurence Serre
- Inserm U1216, CEA, CNRS, Grenoble Institut Neurosciences (GIN), Université Grenoble Alpes, 38000 Grenoble, France
| | - Isabelle Arnal
- Inserm U1216, CEA, CNRS, Grenoble Institut Neurosciences (GIN), Université Grenoble Alpes, 38000 Grenoble, France
| | - Laurent Richard-Parpaillon
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR17 6290, 35000 Rennes, France
| | - Matthew Scott Savoian
- School of Fundamental Sciences, Massey University, 4410 Palmerston North, New Zealand
| | - Régis Giet
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR17 6290, 35000 Rennes, France.
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11
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Deng Q, Tan YS, Chew LY, Wang H. Msps governs acentrosomal microtubule assembly and reactivation of quiescent neural stem cells. EMBO J 2021; 40:e104549. [PMID: 34368973 PMCID: PMC8488572 DOI: 10.15252/embj.2020104549] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 07/05/2021] [Accepted: 07/09/2021] [Indexed: 12/11/2022] Open
Abstract
The ability of stem cells to switch between quiescence and proliferation is crucial for tissue homeostasis and regeneration. Drosophila quiescent neural stem cells (NSCs) extend a primary cellular protrusion from the cell body prior to their reactivation. However, the structure and function of this protrusion are not well established. Here, we show that in the protrusion of quiescent NSCs, microtubules are predominantly acentrosomal and oriented plus‐end‐out toward the tip of the primary protrusion. We have identified Mini Spindles (Msps)/XMAP215 as a key microtubule regulator in quiescent NSCs that governs NSC reactivation via regulating acentrosomal microtubule growth and orientation. We show that quiescent NSCs form membrane contact with the neuropil and E‐cadherin, a cell adhesion molecule, localizes to these NSC‐neuropil junctions. Msps and a plus‐end directed motor protein Kinesin‐2 promote NSC cell cycle re‐entry and target E‐cadherin to NSC‐neuropil contact during NSC reactivation. Together, this work establishes acentrosomal microtubule organization in the primary protrusion of quiescent NSCs and the Msps‐Kinesin‐2 pathway that governs NSC reactivation, in part, by targeting E‐cad to NSC‐neuropil contact sites.
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Affiliation(s)
- Qiannan Deng
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, Singapore, Singapore
| | - Ye Sing Tan
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, Singapore, Singapore
| | - Liang Yuh Chew
- Temasek Life Sciences Laboratory, Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Hongyan Wang
- Neuroscience & Behavioral Disorders Programme, Duke-NUS Medical School, Singapore, Singapore.,NUS Graduate School - Integrative Sciences and Engineering Programme (ISEP), National University of Singapore, Singapore, Singapore.,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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12
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Krüger LK, Gélin M, Ji L, Kikuti C, Houdusse A, Théry M, Blanchoin L, Tran PT. Kinesin-6 Klp9 orchestrates spindle elongation by regulating microtubule sliding and growth. eLife 2021; 10:67489. [PMID: 34080538 PMCID: PMC8205488 DOI: 10.7554/elife.67489] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 06/02/2021] [Indexed: 11/13/2022] Open
Abstract
Mitotic spindle function depends on the precise regulation of microtubule dynamics and microtubule sliding. Throughout mitosis, both processes have to be orchestrated to establish and maintain spindle stability. We show that during anaphase B spindle elongation in Schizosaccharomyces pombe, the sliding motor Klp9 (kinesin-6) also promotes microtubule growth in vivo. In vitro, Klp9 can enhance and dampen microtubule growth, depending on the tubulin concentration. This indicates that the motor is able to promote and block tubulin subunit incorporation into the microtubule lattice in order to set a well-defined microtubule growth velocity. Moreover, Klp9 recruitment to spindle microtubules is dependent on its dephosphorylation mediated by XMAP215/Dis1, a microtubule polymerase, creating a link between the regulation of spindle length and spindle elongation velocity. Collectively, we unravel the mechanism of anaphase B, from Klp9 recruitment to the motors dual-function in regulating microtubule sliding and microtubule growth, allowing an inherent coordination of both processes.
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Affiliation(s)
- Lara Katharina Krüger
- Institut Curie, PSL Research University, Sorbonne Université CNRS, UMR 144, Paris, France
| | - Matthieu Gélin
- Institut de Recherche Saint Louis,U976 Human Immunology Pathophysiology Immunotherapy (HIPI), CytoMorpho Lab, University of Paris, INSERM, CEA, Paris, France
| | - Liang Ji
- Institut Curie, PSL Research University, Sorbonne Université CNRS, UMR 144, Paris, France
| | - Carlos Kikuti
- Institut Curie, PSL Research University, Sorbonne Université CNRS, UMR 144, Paris, France
| | - Anne Houdusse
- Institut Curie, PSL Research University, Sorbonne Université CNRS, UMR 144, Paris, France
| | - Manuel Théry
- Institut de Recherche Saint Louis,U976 Human Immunology Pathophysiology Immunotherapy (HIPI), CytoMorpho Lab, University of Paris, INSERM, CEA, Paris, France.,Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorpho Lab, University of Grenoble-Alpes, CEA, CNRS, INRA, Grenoble, Paris, France
| | - Laurent Blanchoin
- Institut de Recherche Saint Louis,U976 Human Immunology Pathophysiology Immunotherapy (HIPI), CytoMorpho Lab, University of Paris, INSERM, CEA, Paris, France.,Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorpho Lab, University of Grenoble-Alpes, CEA, CNRS, INRA, Grenoble, Paris, France
| | - Phong T Tran
- Institut Curie, PSL Research University, Sorbonne Université CNRS, UMR 144, Paris, France.,Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, United States
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13
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Lattao R, Rangone H, Llamazares S, Glover DM. Mauve/LYST limits fusion of lysosome-related organelles and promotes centrosomal recruitment of microtubule nucleating proteins. Dev Cell 2021; 56:1000-1013.e6. [PMID: 33725482 PMCID: PMC8024676 DOI: 10.1016/j.devcel.2021.02.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 11/17/2020] [Accepted: 02/17/2021] [Indexed: 11/28/2022]
Abstract
Lysosome-related organelles (LROs) are endosomal compartments carrying tissue-specific proteins, which become enlarged in Chediak-Higashi syndrome (CHS) due to mutations in LYST. Here, we show that Drosophila Mauve, a counterpart of LYST, suppresses vesicle fusion events with lipid droplets (LDs) during the formation of yolk granules (YGs), the LROs of the syncytial embryo, and opposes Rab5, which promotes fusion. Mauve localizes on YGs and at spindle poles, and it co-immunoprecipitates with the LDs' component and microtubule-associated protein Minispindles/Ch-TOG. Minispindles levels are increased at the enlarged YGs and diminished around centrosomes in mauve-derived mutant embryos. This leads to decreased microtubule nucleation from centrosomes, a defect that can be rescued by dominant-negative Rab5. Together, this reveals an unanticipated link between endosomal vesicles and centrosomes. These findings establish Mauve/LYST's role in regulating LRO formation and centrosome behavior, a role that could account for the enlarged LROs and centrosome positioning defects at the immune synapse of CHS patients.
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Affiliation(s)
- Ramona Lattao
- University of Cambridge, Department of Genetics, Downing Street, Cambridge CB23EH, UK.
| | - Hélène Rangone
- University of Cambridge, Department of Genetics, Downing Street, Cambridge CB23EH, UK
| | - Salud Llamazares
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Parc Cientific de Barcelona, C/ Baldiri Reixac 10, 08028 Barcelona, Spain
| | - David M Glover
- University of Cambridge, Department of Genetics, Downing Street, Cambridge CB23EH, UK; Division of Biology and Biological Engineering, California Institute of Technology, 1200 E, California Blvd, Pasadena, CA 91125, USA.
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14
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Herman JA, Miller MP, Biggins S. chTOG is a conserved mitotic error correction factor. eLife 2020; 9:e61773. [PMID: 33377866 PMCID: PMC7773332 DOI: 10.7554/elife.61773] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 12/22/2020] [Indexed: 12/28/2022] Open
Abstract
Accurate chromosome segregation requires kinetochores on duplicated chromatids to biorient by attaching to dynamic microtubules from opposite spindle poles, which exerts forces to bring kinetochores under tension. However, kinetochores initially bind to microtubules indiscriminately, resulting in errors that must be corrected. While the Aurora B protein kinase destabilizes low-tension attachments by phosphorylating kinetochores, low-tension attachments are intrinsically less stable than those under higher tension in vitro independent of Aurora activity. Intrinsic tension-sensitive behavior requires the microtubule regulator Stu2 (budding yeast Dis1/XMAP215 ortholog), which we demonstrate here is likely a conserved function for the TOG protein family. The human TOG protein, chTOG, localizes to kinetochores independent of microtubules by interacting with Hec1. We identify a chTOG mutant that regulates microtubule dynamics but accumulates erroneous kinetochore-microtubule attachments that are not destabilized by Aurora B. Thus, TOG proteins confer a unique, intrinsic error correction activity to kinetochores that ensures accurate chromosome segregation.
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Affiliation(s)
- Jacob A Herman
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - Matthew P Miller
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research CenterSeattleUnited States
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15
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Tang Q, Rui M, Bu S, Wang Y, Chew LY, Yu F. A microtubule polymerase is required for microtubule orientation and dendrite pruning in Drosophila. EMBO J 2020; 39:e103549. [PMID: 32267553 DOI: 10.15252/embj.2019103549] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 02/27/2020] [Accepted: 02/28/2020] [Indexed: 01/12/2023] Open
Abstract
Drosophila class IV ddaC neurons selectively prune all larval dendrites to refine the nervous system during metamorphosis. During dendrite pruning, severing of proximal dendrites is preceded by local microtubule (MT) disassembly. Here, we identify an unexpected role of Mini spindles (Msps), a conserved MT polymerase, in governing dendrite pruning. Msps associates with another MT-associated protein TACC, and both stabilize each other in ddaC neurons. Moreover, Msps and TACC are required to orient minus-end-out MTs in dendrites. We further show that the functions of msps in dendritic MT orientation and dendrite pruning are antagonized by the kinesin-13 MT depolymerase Klp10A. Excessive MT depolymerization, which is induced by pharmacological treatment and katanin overexpression, also perturbs dendritic MT orientation and dendrite pruning, phenocopying msps mutants. Thus, we demonstrate that the MT polymerase Msps is required to form dendritic minus-end-out MTs and thereby promotes dendrite pruning in Drosophila sensory neurons.
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Affiliation(s)
- Quan Tang
- Temasek Life Sciences Laboratory, Singapore City, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore City, Singapore
| | - Menglong Rui
- Temasek Life Sciences Laboratory, Singapore City, Singapore
| | - Shufeng Bu
- Temasek Life Sciences Laboratory, Singapore City, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore City, Singapore
| | - Yan Wang
- Temasek Life Sciences Laboratory, Singapore City, Singapore
| | - Liang Yuh Chew
- Temasek Life Sciences Laboratory, Singapore City, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore City, Singapore
| | - Fengwei Yu
- Temasek Life Sciences Laboratory, Singapore City, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore City, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, Centre for Life Sciences, Singapore City, Singapore.,Neuroscience and Behavioral Disorder Program, Duke-NUS Graduate Medical School Singapore, Singapore City, Singapore
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16
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Pirani V, Métivier M, Gallaud E, Thomas A, Ku S, Chretien D, Ettari R, Giet R, Corsi L, Benaud C. A novel benzodiazepine derivative that suppresses microtubule dynamics and impairs mitotic progression. J Cell Sci 2020; 133:jcs239244. [PMID: 32094264 DOI: 10.1242/jcs.239244] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 02/17/2020] [Indexed: 11/20/2022] Open
Abstract
A novel 2,3-benzodiazepine-4 derivative, named 1g, has recently been shown to function as an anti-proliferative compound. We now show that it perturbs the formation of a functional mitotic spindle, inducing a spindle assembly checkpoint (SAC)-dependent arrest in human cells. Live analysis of individual microtubules indicates that 1g promotes a rapid and reversible reduction in microtubule growth. Unlike most anti-mitotic compounds, we found that 1g does not interfere directly with tubulin or perturb microtubule assembly in vitro The observation that 1g also triggers a SAC-dependent mitotic delay associated with chromosome segregation in Drosophila neural stem cells, suggests that it targets a conserved microtubule regulation module in humans and flies. Altogether, our results indicate that 1g is a novel promising anti-mitotic drug with the unique properties of altering microtubule growth and mitotic spindle organization.
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Affiliation(s)
- Vittoria Pirani
- University of Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, 35000 Rennes, France
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy
| | - Mathieu Métivier
- University of Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, 35000 Rennes, France
| | - Emmanuel Gallaud
- University of Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, 35000 Rennes, France
| | - Alexandre Thomas
- University of Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, 35000 Rennes, France
| | - Siou Ku
- University of Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, 35000 Rennes, France
| | - Denis Chretien
- University of Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, 35000 Rennes, France
| | - Roberta Ettari
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98168 Messina, Italy
| | - Regis Giet
- University of Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, 35000 Rennes, France
| | - Lorenzo Corsi
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy
| | - Christelle Benaud
- University of Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, 35000 Rennes, France
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17
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Chou VT, Johnson S, Long J, Vounatsos M, Van Vactor D. dTACC restricts bouton addition and regulates microtubule organization at the Drosophila neuromuscular junction. Cytoskeleton (Hoboken) 2020; 77:4-15. [PMID: 31702858 PMCID: PMC7027520 DOI: 10.1002/cm.21578] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 10/11/2019] [Accepted: 11/05/2019] [Indexed: 12/20/2022]
Abstract
Regulation of the synaptic cytoskeleton is essential to proper neuronal development and wiring. Perturbations in neuronal microtubules (MTs) are associated with numerous pathologies, yet it remains unclear how changes in MTs may be coupled to synapse morphogenesis. Studies have identified many MT regulators that promote synapse growth. However, less is known about the factors that restrict growth, despite the potential links of synaptic overgrowth to severe neurological conditions. Here, we report that dTACC, which is implicated in MT assembly and stability, prevents synapse overgrowth at the Drosophila neuromuscular junction by restricting addition of new boutons throughout larval development. dTACC localizes to the axonal MT lattice and is required to maintain tubulin levels and the integrity of higher-order MT structures in motor axon terminals. While previous reports have demonstrated the roles of MT-stabilizing proteins in promoting synapse growth, our findings suggest that in certain contexts, MT stabilization may correlate with restricted growth.
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Affiliation(s)
- Vivian T. Chou
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
| | - Seth Johnson
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
| | - Jennifer Long
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
| | - Maxime Vounatsos
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
| | - David Van Vactor
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
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18
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Amin MA, Agarwal S, Varma D. Mapping the kinetochore MAP functions required for stabilizing microtubule attachments to chromosomes during metaphase. Cytoskeleton (Hoboken) 2019; 76:398-412. [PMID: 31454167 DOI: 10.1002/cm.21559] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 08/07/2019] [Accepted: 08/22/2019] [Indexed: 12/24/2022]
Abstract
In mitosis, faithful chromosome segregation is orchestrated by the dynamic interactions between the spindle microtubules (MTs) emanating from the opposite poles and the kinetochores of the chromosomes. However, the precise mechanism that coordinates the coupling of the kinetochore components to dynamic MTs has been a long-standing question. Microtubule-associated proteins (MAPs) regulate MT nucleation and dynamics, MT-mediated transport and MT cross-linking in cells. During mitosis, MAPs play an essential role not only in determining spindle length, position, and orientation but also in facilitating robust kinetochore-microtubule (kMT) attachments by linking the kinetochores to spindle MTs efficiently. The stability of MTs imparted by the MAPs is critical to ensure accurate chromosome segregation. This review primarily focuses on the specific function of nonmotor kinetochore MAPs, their recruitment to kinetochores and their MT-binding properties. We also attempt to synthesize and strengthen our understanding of how these MAPs work in coordination with the kinetochore-bound Ndc80 complex (the key component at the MT-binding interface in metaphase and anaphase) to establish stable kMT attachments and control accurate chromosome segregation during mitosis.
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Affiliation(s)
- Mohammed A Amin
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Shivangi Agarwal
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Dileep Varma
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
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19
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Structures of TOG1 and TOG2 from the human microtubule dynamics regulator CLASP1. PLoS One 2019; 14:e0219823. [PMID: 31323070 PMCID: PMC6641166 DOI: 10.1371/journal.pone.0219823] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 07/03/2019] [Indexed: 12/16/2022] Open
Abstract
Tubulin-binding TOG domains are found arrayed in a number of proteins that regulate microtubule dynamics. While much is known about the structure and function of TOG domains from the XMAP215 microtubule polymerase family, less in known about the TOG domain array found in animal CLASP family members. The animal CLASP TOG array promotes microtubule pause, potentiates rescue, and limits catastrophe. How structurally distinct the TOG domains of animal CLASP are from one another, from XMAP215 family TOG domains, and whether a specific order of structurally distinct TOG domains in the TOG array is conserved across animal CLASP family members is poorly understood. We present the x-ray crystal structures of Homo sapiens (H.s.) CLASP1 TOG1 and TOG2. The structures of H.s. CLASP1 TOG1 and TOG2 are distinct from each other and from the previously determined structure of Mus musculus (M.m.) CLASP2 TOG3. Comparative analyses of CLASP family TOG domain structures determined to date across species and paralogs supports a conserved CLASP TOG array paradigm in which structurally distinct TOG domains are arrayed in a specific order. H.s. CLASP1 TOG1 bears structural similarity to the free-tubulin binding TOG domains of the XMAP215 family but lacks many of the key tubulin-binding determinants found in XMAP215 family TOG domains. This aligns with studies that report that animal CLASP family TOG1 domains cannot bind free tubulin or microtubules. In contrast, animal CLASP family TOG2 and TOG3 domains have reported microtubule-binding activity but are structurally distinct from the free-tubulin binding TOG domains of the XMAP215 family. H.s. CLASP1 TOG2 has a convex architecture, predicted to engage a hyper-curved tubulin state that may underlie its ability to limit microtubule catastrophe and promote rescue. M.m. CLASP2 TOG3 has unique structural elements in the C-terminal half of its α-solenoid domain that our modeling studies implicate in binding to laterally-associated tubulin subunits in the microtubule lattice in a mode similar to, yet distinct from those predicted for the XMAP215 family TOG4 domain. The potential ability of the animal CLASP family TOG3 domain to engage lateral tubulin subunits may underlie the microtubule rescue activity ascribed to the domain. These findings highlight the structural diversity of TOG domains within the CLASP family TOG array and provide a molecular foundation for understanding CLASP-dependent effects on microtubule dynamics.
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20
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Pavlova GA, Razuvaeva AV, Popova JV, Andreyeva EN, Yarinich LA, Lebedev MO, Pellacani C, Bonaccorsi S, Somma MP, Gatti M, Pindyurin AV. The role of Patronin in Drosophila mitosis. BMC Mol Cell Biol 2019; 20:7. [PMID: 31284878 PMCID: PMC6469034 DOI: 10.1186/s12860-019-0189-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Background The calmodulin-regulated spectrin-associated proteins (CAMSAPs) belong to a conserved protein family, which includes members that bind the polymerizing mcrotubule (MT) minus ends and remain associated with the MT lattice formed by minus end polymerization. Only one of the three mammalian CAMSAPs, CAMSAP1, localizes to the mitotic spindle but its function is unclear. In Drosophila, there is only one CAMSAP, named Patronin. Previous work has shown that Patronin stabilizes the minus ends of non-mitotic MTs and is required for proper spindle elongation. However, the precise role of Patronin in mitotic spindle assembly is poorly understood. Results Here we have explored the role of Patronin in Drosophila mitosis using S2 tissue culture cells as a model system. We show that Patronin associates with different types of MT bundles within the Drosophila mitotic spindle, and that it is required for their stability. Imaging of living cells expressing Patronin-GFP showed that Patronin displays a dynamic behavior. In prometaphase cells, Patronin accumulates on short segments of MT bundles located near the chromosomes. These Patronin “seeds” extend towards the cell poles and stop growing just before reaching the poles. Our data also suggest that Patronin localization is largely independent of proteins acting at the MT minus ends such as Asp and Klp10A. Conclusion Our results suggest a working hypothesis about the mitotic role of Patronin. We propose that Patronin binds the minus ends within MT bundles, including those generated from the walls of preexisting MTs via the augmin-mediated pathway. This would help maintaining MT association within the mitotic bundles, thereby stabilizing the spindle structure. Our data also raise the intriguing possibility that the minus ends of bundled MTs can undergo a limited polymerization. Electronic supplementary material The online version of this article (10.1186/s12860-019-0189-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gera A Pavlova
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia
| | - Alyona V Razuvaeva
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Julia V Popova
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia
| | - Evgeniya N Andreyeva
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia
| | - Lyubov A Yarinich
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Mikhail O Lebedev
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Claudia Pellacani
- IBPM CNR and Department of Biology and Biotechnology, Sapienza University of Rome, 00185, Rome, Italy
| | - Silvia Bonaccorsi
- IBPM CNR and Department of Biology and Biotechnology, Sapienza University of Rome, 00185, Rome, Italy
| | - Maria Patrizia Somma
- IBPM CNR and Department of Biology and Biotechnology, Sapienza University of Rome, 00185, Rome, Italy
| | - Maurizio Gatti
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia. .,IBPM CNR and Department of Biology and Biotechnology, Sapienza University of Rome, 00185, Rome, Italy.
| | - Alexey V Pindyurin
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia. .,Novosibirsk State University, Novosibirsk, 630090, Russia.
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21
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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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22
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Tillery MML, Blake-Hedges C, Zheng Y, Buchwalter RA, Megraw TL. Centrosomal and Non-Centrosomal Microtubule-Organizing Centers (MTOCs) in Drosophila melanogaster. Cells 2018; 7:E121. [PMID: 30154378 PMCID: PMC6162459 DOI: 10.3390/cells7090121] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 08/19/2018] [Accepted: 08/20/2018] [Indexed: 12/14/2022] Open
Abstract
The centrosome is the best-understood microtubule-organizing center (MTOC) and is essential in particular cell types and at specific stages during Drosophila development. The centrosome is not required zygotically for mitosis or to achieve full animal development. Nevertheless, centrosomes are essential maternally during cleavage cycles in the early embryo, for male meiotic divisions, for efficient division of epithelial cells in the imaginal wing disc, and for cilium/flagellum assembly in sensory neurons and spermatozoa. Importantly, asymmetric and polarized division of stem cells is regulated by centrosomes and by the asymmetric regulation of their microtubule (MT) assembly activity. More recently, the components and functions of a variety of non-centrosomal microtubule-organizing centers (ncMTOCs) have begun to be elucidated. Throughout Drosophila development, a wide variety of unique ncMTOCs form in epithelial and non-epithelial cell types at an assortment of subcellular locations. Some of these cell types also utilize the centrosomal MTOC, while others rely exclusively on ncMTOCs. The impressive variety of ncMTOCs being discovered provides novel insight into the diverse functions of MTOCs in cells and tissues. This review highlights our current knowledge of the composition, assembly, and functional roles of centrosomal and non-centrosomal MTOCs in Drosophila.
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Affiliation(s)
- Marisa M L Tillery
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Caitlyn Blake-Hedges
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Yiming Zheng
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Rebecca A Buchwalter
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
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23
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Uncovering Genomic Regions Associated with Trypanosoma Infections in Wild Populations of the Tsetse Fly Glossina fuscipes. G3-GENES GENOMES GENETICS 2018; 8:887-897. [PMID: 29343494 PMCID: PMC5844309 DOI: 10.1534/g3.117.300493] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Vector-borne diseases are responsible for > 1 million deaths every year but genomic resources for most species responsible for their transmission are limited. This is true for neglected diseases such as sleeping sickness (Human African Trypanosomiasis), a disease caused by Trypanosoma parasites vectored by several species of tseste flies within the genus Glossina. We describe an integrative approach that identifies statistical associations between trypanosome infection status of Glossina fuscipes fuscipes (Gff) flies from Uganda, for which functional studies are complicated because the species cannot be easily maintained in laboratory colonies, and ∼73,000 polymorphic sites distributed across the genome. Then, we identify candidate genes involved in Gff trypanosome susceptibility by taking advantage of genomic resources from a closely related species, G. morsitans morsitans (Gmm). We compiled a comprehensive transcript library from 72 published and unpublished RNAseq experiments of trypanosome-infected and uninfected Gmm flies, and improved the current Gmm transcriptome assembly. This new assembly was then used to enhance the functional annotations on the Gff genome. As a consequence, we identified 56 candidate genes in the vicinity of the 18 regions associated with Trypanosoma infection status in Gff. Twenty-nine of these genes were differentially expressed (DE) among parasite-infected and uninfected Gmm, suggesting that their orthologs in Gff may correlate with disease transmission. These genes were involved in DNA regulation, neurophysiological functions, and immune responses. We highlight the power of integrating population and functional genomics from related species to enhance our understanding of the genetic basis of physiological traits, particularly in nonmodel organisms.
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24
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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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25
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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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26
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Abstract
The mitotic spindle has a crucial role in ensuring the accurate segregation of chromosomes into the two daughter cells during cell division, which is paramount for maintaining genome integrity. It is a self-organized and dynamic macromolecular structure that is constructed from microtubules, microtubule-associated proteins and motor proteins. Thirty years of research have led to the identification of centrosome-, chromatin- and microtubule-mediated microtubule nucleation pathways that each contribute to mitotic spindle assembly. Far from being redundant pathways, data are now emerging regarding how they function together to ensure the timely completion of mitosis. We are also beginning to comprehend the multiple mechanisms by which cells regulate spindle scaling. Together, this research has increased our understanding of how cells coordinate hundreds of proteins to assemble the dynamic, precise and robust structure that is the mitotic spindle.
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Collaborative Control of Cell Cycle Progression by the RNA Exonuclease Dis3 and Ras Is Conserved Across Species. Genetics 2016; 203:749-62. [PMID: 27029730 DOI: 10.1534/genetics.116.187930] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 03/26/2016] [Indexed: 11/18/2022] Open
Abstract
Dis3 encodes a conserved RNase that degrades or processes all RNA species via an N-terminal PilT N terminus (PIN) domain and C-terminal RNB domain that harbor, respectively, endonuclease activity and 3'-5' exonuclease activity. In Schizosaccharomyces pombe, dis3 mutations cause chromosome missegregation and failure in mitosis, suggesting dis3 promotes cell division. In humans, apparently hypomorphic dis3 mutations are found recurrently in multiple myeloma, suggesting dis3 opposes cell division. Except for the observation that RNAi-mediated depletion of dis3 function drives larval arrest and reduces tissue growth in Drosophila, the role of dis3 has not been rigorously explored in higher eukaryotic systems. Using the Drosophila system and newly generated dis3 null alleles, we find that absence of dis3 activity inhibits cell division. We uncover a conserved CDK1 phosphorylation site that when phosphorylated inhibits Dis3's exonuclease, but not endonuclease, activity. Leveraging this information, we show that Dis3's exonuclease function is required for mitotic cell division: in its absence, cells are delayed in mitosis and exhibit aneuploidy and overcondensed chromosomes. In contrast, we find that modest reduction of dis3 function enhances cell proliferation in the presence of elevated Ras activity, apparently by accelerating cells through G2/M even though each insult by itself delays G2/M. Additionally, we find that dis3 and ras genetically interact in worms and that dis3 can enhance cell proliferation under growth stimulatory conditions in murine B cells. Thus, reduction, but not absence, of dis3 activity can enhance cell proliferation in higher organisms.
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28
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Chen K, Koe CT, Xing ZB, Tian X, Rossi F, Wang C, Tang Q, Zong W, Hong WJ, Taneja R, Yu F, Gonzalez C, Wu C, Endow S, Wang H. Arl2- and Msps-dependent microtubule growth governs asymmetric division. J Cell Biol 2016; 212:661-76. [PMID: 26953351 PMCID: PMC4792071 DOI: 10.1083/jcb.201503047] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 02/10/2016] [Indexed: 12/18/2022] Open
Abstract
Drosophila Arl2 governs neuroblast asymmetric cell division through regulation of microtubule growth and localization of Msps to centrosomes. Asymmetric division of neural stem cells is a fundamental strategy to balance their self-renewal and differentiation. It is long thought that microtubules are not essential for cell polarity in asymmetrically dividing Drosophila melanogaster neuroblasts (NBs; neural stem cells). Here, we show that Drosophila ADP ribosylation factor like-2 (Arl2) and Msps, a known microtubule-binding protein, control cell polarity and spindle orientation of NBs. Upon arl2 RNA intereference, Arl2-GDP expression, or arl2 deletions, microtubule abnormalities and asymmetric division defects were observed. Conversely, overactivation of Arl2 leads to microtubule overgrowth and depletion of NBs. Arl2 regulates microtubule growth and asymmetric division through localizing Msps to the centrosomes in NBs. Moreover, Arl2 regulates dynein function and in turn centrosomal localization of D-TACC and Msps. Arl2 physically associates with tubulin cofactors C, D, and E. Arl2 functions together with tubulin-binding cofactor D to control microtubule growth, Msps localization, and NB self-renewal. Therefore, Arl2- and Msps-dependent microtubule growth is a new paradigm regulating asymmetric division of neural stem cells.
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Affiliation(s)
- Keng Chen
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore 169857 National University of Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456
| | - Chwee Tat Koe
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore 169857 National University of Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456
| | - Zhanyuan Benny Xing
- Department of Cell Biology, Duke University, Duke University Medical Center, Durham, NC 27710
| | - Xiaolin Tian
- Neuroscience Center of Excellence, Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, New Orleans, LA 70112
| | - Fabrizio Rossi
- Institute for Research in Biomedicine Barcelona, 08028 Barcelona, Spain
| | - Cheng Wang
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore 169857
| | - Quan Tang
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604 Department of Biological Sciences, National University of Singapore, Singapore 117604
| | - Wenhui Zong
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604 Department of Biological Sciences, National University of Singapore, Singapore 117604
| | - Wan Jin Hong
- Institute of Molecular and Cell Biology, Singapore 138673
| | - Reshma Taneja
- National University of Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597
| | - Fengwei Yu
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore 169857 National University of Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604 Department of Biological Sciences, National University of Singapore, Singapore 117604
| | - Cayetano Gonzalez
- Institute for Research in Biomedicine Barcelona, 08028 Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
| | - Chunlai Wu
- Neuroscience Center of Excellence, Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, New Orleans, LA 70112
| | - Sharyn Endow
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore 169857 Department of Cell Biology, Duke University, Duke University Medical Center, Durham, NC 27710
| | - Hongyan Wang
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore 169857 National University of Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597
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29
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Głuszek AA, Cullen CF, Li W, Battaglia RA, Radford SJ, Costa MF, McKim KS, Goshima G, Ohkura H. The microtubule catastrophe promoter Sentin delays stable kinetochore-microtubule attachment in oocytes. J Cell Biol 2015; 211:1113-20. [PMID: 26668329 PMCID: PMC4687879 DOI: 10.1083/jcb.201507006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 11/12/2015] [Indexed: 01/08/2023] Open
Abstract
The microtubule catastrophe-promoting complex Sentin-EB1 delays stable kinetochore–microtubule attachment and facilitates bipolar attachment of homologous chromosomes in Drosophila oocytes. The critical step in meiosis is to attach homologous chromosomes to the opposite poles. In mouse oocytes, stable microtubule end-on attachments to kinetochores are not established until hours after spindle assembly, and phosphorylation of kinetochore proteins by Aurora B/C is responsible for the delay. Here we demonstrated that microtubule ends are actively prevented from stable attachment to kinetochores until well after spindle formation in Drosophila melanogaster oocytes. We identified the microtubule catastrophe-promoting complex Sentin-EB1 as a major factor responsible for this delay. Without this activity, microtubule ends precociously form robust attachments to kinetochores in oocytes, leading to a high proportion of homologous kinetochores stably attached to the same pole. Therefore, regulation of microtubule ends provides an alternative novel mechanism to delay stable kinetochore–microtubule attachment in oocytes.
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Affiliation(s)
- A Agata Głuszek
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - C Fiona Cullen
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - Wenjing Li
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | | | | | - Mariana F Costa
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - Kim S McKim
- Waksman Institute, Rutgers University, Piscataway, NJ 08854
| | - Gohta Goshima
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Hiroyuki Ohkura
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
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30
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Abstract
A metaphase spindle is a complex structure consisting of microtubules and a myriad of different proteins that modulate microtubule dynamics together with chromatin and kinetochores. A decade ago, a full description of spindle formation and function seemed a lofty goal. Here, we describe how work in the last 10 years combining cataloging of spindle components, the characterization of their biochemical activities using single-molecule techniques, and theory have advanced our knowledge. Taken together, these advances suggest that a full understanding of spindle assembly and function may soon be possible.
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Affiliation(s)
- Simone Reber
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany Integrative Research Institute (IRI) for the Life Sciences, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
| | - Anthony A Hyman
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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31
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Sato K, Siomi MC. Functional and structural insights into the piRNA factor Maelstrom. FEBS Lett 2015; 589:1688-93. [DOI: 10.1016/j.febslet.2015.03.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 03/19/2015] [Indexed: 10/23/2022]
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32
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Howard AE, Fox JC, Slep KC. Drosophila melanogaster mini spindles TOG3 utilizes unique structural elements to promote domain stability and maintain a TOG1- and TOG2-like tubulin-binding surface. J Biol Chem 2015; 290:10149-62. [PMID: 25720490 DOI: 10.1074/jbc.m114.633826] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Indexed: 11/06/2022] Open
Abstract
Microtubule-associated proteins regulate microtubule (MT) dynamics spatially and temporally, which is essential for proper formation of the bipolar mitotic spindle. The XMAP215 family is comprised of conserved microtubule-associated proteins that use an array of tubulin-binding tumor overexpressed gene (TOG) domains, consisting of six (A-F) Huntingtin, elongation factor 3, protein phosphatase 2A, target of rapamycin (HEAT) repeats, to robustly increase MT plus-end polymerization rates. Recent work showed that TOG domains have differentially conserved architectures across the array, with implications for position-dependent TOG domain tubulin binding activities and function within the XMAP215 MT polymerization mechanism. Although TOG domains 1, 2, and 4 are well described, structural and mechanistic information characterizing TOG domains 3 and 5 is outstanding. Here, we present the structure and characterization of Drosophila melanogaster Mini spindles (Msps) TOG3. Msps TOG3 has two unique features as follows: the first is a C-terminal tail that stabilizes the ultimate four HEAT repeats (HRs), and the second is a unique architecture in HR B. Structural alignments of TOG3 with other TOG domain structures show that the architecture of TOG3 is most similar to TOG domains 1 and 2 and diverges from TOG4. Docking TOG3 onto recently solved Stu2 TOG1· and TOG2·tubulin complex structures suggests that TOG3 uses similarly conserved tubulin-binding intra-HEAT loop residues to engage α- and β-tubulin. This indicates that TOG3 has maintained a TOG1- and TOG2-like TOG-tubulin binding mode despite structural divergence. The similarity of TOG domains 1-3 and the divergence of TOG4 suggest that a TOG domain array with polarized structural diversity may play a key mechanistic role in XMAP215-dependent MT polymerization activity.
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Affiliation(s)
- Amy E Howard
- From the Department of Biochemistry and Biophysics, Program in Molecular and Cellular Biophysics, and
| | - Jaime C Fox
- From the Department of Biochemistry and Biophysics, Program in Molecular and Cellular Biophysics, and
| | - Kevin C Slep
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599
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33
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Abstract
Microtubules are dynamic polymers of αβ-tubulin that form diverse cellular structures, such as the mitotic spindle for cell division, the backbone of neurons, and axonemes. To control the architecture of microtubule networks, microtubule-associated proteins (MAPs) and motor proteins regulate microtubule growth, shrinkage, and the transitions between these states. Recent evidence shows that many MAPs exert their effects by selectively binding to distinct conformations of polymerized or unpolymerized αβ-tubulin. The ability of αβ-tubulin to adopt distinct conformations contributes to the intrinsic polymerization dynamics of microtubules. αβ-Tubulin conformation is a fundamental property that MAPs monitor and control to build proper microtubule networks.
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Affiliation(s)
- Gary J Brouhard
- Department of Biology, McGill University, Montréal, Quebec, Canada H3A1B1
| | - Luke M Rice
- Department of Biophysics and Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390 Department of Biophysics and Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390
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34
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Ferreira JG, Pereira AL, Maiato H. Microtubule plus-end tracking proteins and their roles in cell division. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 309:59-140. [PMID: 24529722 DOI: 10.1016/b978-0-12-800255-1.00002-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Microtubules are cellular components that are required for a variety of essential processes such as cell motility, mitosis, and intracellular transport. This is possible because of the inherent dynamic properties of microtubules. Many of these properties are tightly regulated by a number of microtubule plus-end-binding proteins or +TIPs. These proteins recognize the distal end of microtubules and are thus in the right context to control microtubule dynamics. In this review, we address how microtubule dynamics are regulated by different +TIP families, focusing on how functionally diverse +TIPs spatially and temporally regulate microtubule dynamics during animal cell division.
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Affiliation(s)
- Jorge G Ferreira
- Chromosome Instability & Dynamics Laboratory, Instituto de Biologia Molecular e Celular, University of Porto, Porto, Portugal; Cell Division Unit, Department of Experimental Biology, University of Porto, Porto, Portugal
| | - Ana L Pereira
- Chromosome Instability & Dynamics Laboratory, Instituto de Biologia Molecular e Celular, University of Porto, Porto, Portugal
| | - Helder Maiato
- Chromosome Instability & Dynamics Laboratory, Instituto de Biologia Molecular e Celular, University of Porto, Porto, Portugal; Cell Division Unit, Department of Experimental Biology, University of Porto, Porto, Portugal.
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35
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Fox JC, Howard AE, Currie JD, Rogers SL, Slep KC. The XMAP215 family drives microtubule polymerization using a structurally diverse TOG array. Mol Biol Cell 2014; 25:2375-92. [PMID: 24966168 PMCID: PMC4142611 DOI: 10.1091/mbc.e13-08-0501] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
XMAP215 family members are potent microtubule (MT) polymerases, with mutants displaying reduced MT growth rates and aberrant spindle morphologies. XMAP215 proteins contain arrayed tumor overexpressed gene (TOG) domains that bind tubulin. Whether these TOG domains are architecturally equivalent is unknown. Here we present crystal structures of TOG4 from Drosophila Msps and human ch-TOG. These TOG4 structures architecturally depart from the structures of TOG domains 1 and 2, revealing a conserved domain bend that predicts a novel engagement with α-tubulin. In vitro assays show differential tubulin-binding affinities across the TOG array, as well as differential effects on MT polymerization. We used Drosophila S2 cells depleted of endogenous Msps to assess the importance of individual TOG domains. Whereas a TOG1-4 array largely rescues MT polymerization rates, mutating tubulin-binding determinants in any single TOG domain dramatically reduces rescue activity. Our work highlights the structurally diverse yet positionally conserved TOG array that drives MT polymerization.
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Affiliation(s)
- Jaime C. Fox
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599,Graduate Program in Molecular and Cellular Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Amy E. Howard
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599,Graduate Program in Molecular and Cellular Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Joshua D. Currie
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Stephen L. Rogers
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599,Carolina Center for Genome Science, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599,Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Kevin C. Slep
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599,Address correspondence to: Kevin C. Slep ()
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36
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Gallaud E, Caous R, Pascal A, Bazile F, Gagné JP, Huet S, Poirier GG, Chrétien D, Richard-Parpaillon L, Giet R. Ensconsin/Map7 promotes microtubule growth and centrosome separation in Drosophila neural stem cells. ACTA ACUST UNITED AC 2014; 204:1111-21. [PMID: 24687279 PMCID: PMC3971751 DOI: 10.1083/jcb.201311094] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ensconsin cooperates with its binding partner, Kinesin-1, during interphase to trigger centrosome separation, but it promotes microtubule polymerization independently of Kinesin-1 to control spindle length during mitosis. The mitotic spindle is crucial to achieve segregation of sister chromatids. To identify new mitotic spindle assembly regulators, we isolated 855 microtubule-associated proteins (MAPs) from Drosophila melanogaster mitotic or interphasic embryos. Using RNAi, we screened 96 poorly characterized genes in the Drosophila central nervous system to establish their possible role during spindle assembly. We found that Ensconsin/MAP7 mutant neuroblasts display shorter metaphase spindles, a defect caused by a reduced microtubule polymerization rate and enhanced by centrosome ablation. In agreement with a direct effect in regulating spindle length, Ensconsin overexpression triggered an increase in spindle length in S2 cells, whereas purified Ensconsin stimulated microtubule polymerization in vitro. Interestingly, ensc-null mutant flies also display defective centrosome separation and positioning during interphase, a phenotype also detected in kinesin-1 mutants. Collectively, our results suggest that Ensconsin cooperates with its binding partner Kinesin-1 during interphase to trigger centrosome separation. In addition, Ensconsin promotes microtubule polymerization during mitosis to control spindle length independent of Kinesin-1.
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Affiliation(s)
- Emmanuel Gallaud
- Cytoskeleton and Cell Proliferation, 2 Tubulin and Interacting Proteins, and 3 Spatio-temporal Regulation of Transcription, Biosit, Université de Rennes I, Centre National de la Recherche Scientifique, UMR 6290, 35043 Rennes, France
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37
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Leano JB, Rogers SL, Slep KC. A cryptic TOG domain with a distinct architecture underlies CLASP-dependent bipolar spindle formation. Structure 2014; 21:939-50. [PMID: 23727231 DOI: 10.1016/j.str.2013.04.018] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 04/08/2013] [Accepted: 04/18/2013] [Indexed: 01/29/2023]
Abstract
CLASP is a key regulator of microtubule (MT) dynamics and bipolar mitotic spindle structure with CLASP mutants displaying a distinctive monopolar spindle phenotype. It has been postulated that cryptic TOG domains underlie CLASP’s ability to regulate MT dynamics. Here, we report the crystal structure of a cryptic TOG domain (TOG2) from human CLASP1, demonstrating the presence of a TOG array in the CLASP family. Strikingly, CLASP1 TOG2 exhibits a convex architecture across the tubulin-binding surface that contrasts with the flat tubulin-binding surface of XMAP215 family TOG domains. Mutations in key conserved TOG2 determinants abrogate the ability of CLASP mutants to rescue bipolar spindle formation in Drosophila cells depleted of endogenous CLASP. These findings highlight the common mechanistic use of TOG domains in XMAP215 and CLASP families to regulate MT dynamics and suggest that differential TOG domain architecture may confer distinct functions to these critical cytoskeletal regulators.
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Affiliation(s)
- Jonathan B Leano
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
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38
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Hamada T. Microtubule organization and microtubule-associated proteins in plant cells. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 312:1-52. [PMID: 25262237 DOI: 10.1016/b978-0-12-800178-3.00001-4] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Plants have unique microtubule (MT) arrays, cortical MTs, preprophase band, mitotic spindle, and phragmoplast, in the processes of evolution. These MT arrays control the directions of cell division and expansion especially in plants and are essential for plant morphogenesis and developments. Organizations and functions of these MT arrays are accomplished by diverse MT-associated proteins (MAPs). This review introduces 10 of conserved MAPs in eukaryote such as γ-TuC, augmin, katanin, kinesin, EB1, CLASP, MOR1/MAP215, MAP65, TPX2, formin, and several plant-specific MAPs such as CSI1, SPR2, MAP70, WVD2/WDL, RIP/MIDD, SPR1, MAP18/PCaP, EDE1, and MAP190. Most of the studies cited in this review have been analyzed in the particular model plant, Arabidopsis thaliana. The significant knowledge of A. thaliana is the important established base to understand MT organizations and functions in plants.
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Affiliation(s)
- Takahiro Hamada
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo, Japan.
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Syred HM, Welburn J, Rappsilber J, Ohkura H. Cell cycle regulation of microtubule interactomes: multi-layered regulation is critical for the interphase/mitosis transition. Mol Cell Proteomics 2013; 12:3135-47. [PMID: 23893837 PMCID: PMC3820929 DOI: 10.1074/mcp.m113.028563] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 07/25/2013] [Indexed: 12/17/2022] Open
Abstract
Microtubules dramatically change their dynamics and organization at the entry into mitosis. Although this change is mediated by microtubule-associated proteins (MAPs), how MAPs themselves are regulated is not well understood. Here we used an integrated multi-level approach to establish the framework and biological significance of MAP regulation critical for the interphase/mitosis transition. Firstly, we applied quantitative proteomics to determine global cell cycle changes in the profiles of MAPs in human and Drosophila cells. This uncovered a wide range of cell cycle regulations of MAPs previously unidentified. Secondly, systematic studies of human kinesins highlighted an overlooked aspect of kinesins: most mitotic kinesins suppress their affinity to microtubules or reduce their protein levels in interphase in combination with nuclear localization. Thirdly, in-depth analysis of a novel Drosophila MAP (Mink) revealed that the suppression of the microtubule affinity of this mitotic MAP in combination with nuclear localization is essential for microtubule organization in interphase, and phosphorylation of Mink is needed for kinetochore-microtubule attachment in mitosis. Thus, this first comprehensive analysis of MAP regulation for the interphase/mitosis transition advances our understanding of kinesin biology and reveals the prevalence and importance of multi-layered MAP regulation.
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Affiliation(s)
- Heather M. Syred
- From the ‡Wellcome Trust Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
| | - Julie Welburn
- From the ‡Wellcome Trust Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
| | - Juri Rappsilber
- From the ‡Wellcome Trust Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
| | - Hiroyuki Ohkura
- From the ‡Wellcome Trust Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
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The growth speed of microtubules with XMAP215-coated beads coupled to their ends is increased by tensile force. Proc Natl Acad Sci U S A 2013; 110:14670-5. [PMID: 23964126 DOI: 10.1073/pnas.1218053110] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The generation of pulling and pushing forces is one of the important functions of microtubules, which are dynamic and polarized structures. The ends of dynamic microtubules are able to form relatively stable links to cellular structures, so that when a microtubule grows it can exert a pushing force and when it shrinks it can exert a pulling force. Microtubule growth and shrinkage are tightly regulated by microtubule-associated proteins (MAPs) that bind to microtubule ends. Given their localization, MAPs may be exposed to compressive and tensile forces. The effect of such forces on MAP function, however, is poorly understood. Here we show that beads coated with the microtubule polymerizing protein XMAP215, the Xenopus homolog of Dis1 and chTOG, are able to link stably to the plus ends of microtubules, even when the ends are growing or shrinking; at growing ends, the beads increase the polymerization rate. Using optical tweezers, we found that tensile force further increased the microtubule polymerization rate. These results show that physical forces can regulate the activity of MAPs. Furthermore, our results show that XMAP215 can be used as a handle to sense and mechanically manipulate the dynamics of the microtubule tip.
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Reschen RF, Colombie N, Wheatley L, Dobbelaere J, St Johnston D, Ohkura H, Raff JW. Dgp71WD is required for the assembly of the acentrosomal Meiosis I spindle, and is not a general targeting factor for the γ-TuRC. Biol Open 2012; 1:422-9. [PMID: 23213433 PMCID: PMC3507215 DOI: 10.1242/bio.2012596] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Dgp71WD/Nedd1 proteins are essential for mitotic spindle formation. In human cells, Nedd1 targets γ-tubulin to both centrosomes and spindles, but in other organisms the function of Dgp71WD/Nedd1 is less clear. In Drosophila cells, Dgp71WD plays a major part in targeting γ-tubulin to spindles, but not centrosomes, while in Xenopus egg extracts, Nedd1 acts as a more general microtubule (MT) organiser that can function independently of γ-tubulin. The interpretation of these studies, however, is complicated by the fact that some residual Dgp71WD/Nedd1 is likely present in the cells/extracts analysed. Here we generate a Dgp71WD null mutant lacking all but the last 12 nucleotides of coding sequence. The complete loss of Dgp71WD has no quantifiable effect on γ-tubulin or Centrosomin recruitment to the centrosome in larval brain cells. The recruitment of γ-tubulin to spindle MTs, however, is severely impaired, and spindle MT density is reduced in a manner that is indistinguishable from cells lacking Augmin or γ-TuRC function. In contrast, the absence of Dgp71WD leads to defects in the assembly of the acentrosomal female Meiosis I spindle that are more severe than those seen in Augmin or γ-TuRC mutants, indicating that Dgp71WD has additional functions that are independent of these complexes in oocytes. Moreover, the localisation of bicoid RNA during oogenesis, which requires γ-TuRC function, is unperturbed in Dgp71WD(120) mutants. Thus, Dgp71WD is not simply a general cofactor required for γ-TuRC and/or Augmin targeting, and it appears to have a crucial role independent of these complexes in the acentrosomal Meiosis I spindle.
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Affiliation(s)
- Richard F. Reschen
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Nathalie Colombie
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh, EH9 3JR, UK
| | - Lucy Wheatley
- Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
| | - Jeroen Dobbelaere
- Research Institute of Molecular Pathology (IMP), Dr. Bohr-Gasse 7, 1030 Vienna, Austria
| | - Daniel St Johnston
- Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
| | - Hiro Ohkura
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh, EH9 3JR, UK
| | - Jordan W. Raff
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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Sato K, Nishida KM, Shibuya A, Siomi MC, Siomi H. Maelstrom coordinates microtubule organization during Drosophila oogenesis through interaction with components of the MTOC. Genes Dev 2011; 25:2361-73. [PMID: 22085963 DOI: 10.1101/gad.174110.111] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The establishment of body axes in multicellular organisms requires accurate control of microtubule polarization. Mutations in Drosophila PIWI-interacting RNA (piRNA) pathway genes often disrupt the axes of the oocyte. This results from the activation of the DNA damage checkpoint factor Checkpoint kinase 2 (Chk2) due to transposon derepression. A piRNA pathway gene, maelstrom (mael), is critical for the establishment of oocyte polarity in the developing egg chamber during Drosophila oogenesis. We show that Mael forms complexes with microtubule-organizing center (MTOC) components, including Centrosomin, Mini spindles, and γTubulin. We also show that Mael colocalizes with αTubulin and γTubulin to centrosomes in dividing cyst cells and follicle cells. MTOC components mislocalize in mael mutant germarium and egg chambers, leading to centrosome migration defects. During oogenesis, the loss of mael affects oocyte determination and induces egg chamber fusion. Finally, we show that the axis specification defects in mael mutants are not suppressed by a mutation in mnk, which encodes a Chk2 homolog. These findings suggest a model in which Mael serves as a platform that nucleates other MTOC components to form a functional MTOC in early oocyte development, which is independent of Chk2 activation and DNA damage signaling.
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Affiliation(s)
- Kaoru Sato
- Department of Molecular Biology, Keio University School of Medicine, Tokyo, Japan
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Currie JD, Stewman S, Schimizzi G, Slep KC, Ma A, Rogers SL. The microtubule lattice and plus-end association of Drosophila Mini spindles is spatially regulated to fine-tune microtubule dynamics. Mol Biol Cell 2011; 22:4343-61. [PMID: 21965297 PMCID: PMC3216660 DOI: 10.1091/mbc.e11-06-0520] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Individual microtubules (MTs) exhibit dynamic instability, a behavior in which they cycle between phases of growth and shrinkage while the total amount of MT polymer remains constant. Dynamic instability is promoted by the conserved XMAP215/Dis1 family of microtubule-associated proteins (MAPs). In this study, we conducted an in vivo structure-function analysis of the Drosophila homologue Mini spindles (Msps). Msps exhibits EB1-dependent and spatially regulated MT localization, targeting to microtubule plus ends in the cell interior and decorating the lattice of growing and shrinking microtubules in the cell periphery. RNA interference rescue experiments revealed that the NH(2)-terminal four TOG domains of Msps function as paired units and were sufficient to promote microtubule dynamics and EB1 comet formation. We also identified TOG5 and novel inter-TOG linker motifs that are required for targeting Msps to the microtubule lattice. These novel microtubule contact sites are necessary for the interplay between the conserved TOG domains and inter-TOG MT binding that underlies the ability of Msps to promote MT dynamic instability.
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Affiliation(s)
- Joshua D Currie
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Al-Bassam J, Chang F. Regulation of microtubule dynamics by TOG-domain proteins XMAP215/Dis1 and CLASP. Trends Cell Biol 2011; 21:604-14. [PMID: 21782439 DOI: 10.1016/j.tcb.2011.06.007] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 06/17/2011] [Accepted: 06/20/2011] [Indexed: 12/17/2022]
Abstract
The molecular mechanisms by which microtubule-associated proteins (MAPs) regulate the dynamic properties of microtubules (MTs) are still poorly understood. We review recent advances in our understanding of two conserved families of MAPs, the XMAP215/Dis1 and CLASP family of proteins. In vivo and in vitro studies show that XMAP215 proteins act as microtubule polymerases at MT plus ends to accelerate MT assembly, and CLASP proteins promote MT rescue and suppress MT catastrophe events. These are structurally related proteins that use conserved TOG domains to recruit tubulin dimers to MTs. We discuss models for how these proteins might use these individual tubulin dimers to regulate dynamic behavior of MT plus ends.
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Affiliation(s)
- Jawdat Al-Bassam
- Department of Molecular Cellular Biology, University of California, Davis, CA, USA.
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Yasuhara H, Oe Y. TMBP200, a XMAP215 homologue of tobacco BY-2 cells, has an essential role in plant mitosis. PROTOPLASMA 2011; 248:493-502. [PMID: 20703504 DOI: 10.1007/s00709-010-0189-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Accepted: 07/28/2010] [Indexed: 05/26/2023]
Abstract
TMBP200 from tobacco BY-2 cells is a member of the highly conserved family of microtubule-associated proteins that includes Xenopus XMAP215, human TOGp, and Arabidopsis MOR1/GEM1. XMAP215 homologues have an essential role in spindle assembly and function in animals and yeast, but their role in plant mitosis is not fully clarified. Here, we show by immunoblot analysis that TMBP200 levels in synchronously cultured BY-2 cells increased when the cells entered mitosis, thus indicating that TMBP200 plays an important role in mitosis in tobacco. To investigate the role of TMBP200 in mitosis, we employed inducible RNA interference to silence TMBP200 expression in BY-2 cells. The resulting depletion of TMBP200 caused severe defects in bipolar spindle formation and resulted in the appearance of multinucleated cells with variable-sized nuclei. This finding indicates that TMBP200 has an essential role in bipolar spindle formation and function.
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Affiliation(s)
- Hiroki Yasuhara
- Department of Life Science and Biotechnology, Faculty of Chemistry, Materials and Bioengineering, Kansai University, Suita, Osaka, Japan.
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Parallel genetic and proteomic screens identify Msps as a CLASP-Abl pathway interactor in Drosophila. Genetics 2010; 185:1311-25. [PMID: 20498300 DOI: 10.1534/genetics.110.115626] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Regulation of cytoskeletal structure and dynamics is essential for multiple aspects of cellular behavior, yet there is much to learn about the molecular machinery underlying the coordination between the cytoskeleton and its effector systems. One group of proteins that regulate microtubule behavior and its interaction with other cellular components, such as actin-regulatory proteins and transport machinery, is the plus-end tracking proteins (MT+TIPs). In particular, evidence suggests that the MT+TIP, CLASP, may play a pivotal role in the coordination of microtubules with other cellular structures in multiple contexts, although the molecular mechanism by which it functions is still largely unknown. To gain deeper insight into the functional partners of CLASP, we conducted parallel genetic and proteome-wide screens for CLASP interactors in Drosophila melanogaster. We identified 36 genetic modifiers and 179 candidate physical interactors, including 13 that were identified in both data sets. Grouping interactors according to functional classifications revealed several categories, including cytoskeletal components, signaling proteins, and translation/RNA regulators. We focused our initial investigation on the MT+TIP Minispindles (Msps), identified among the cytoskeletal effectors in both genetic and proteomic screens. Here, we report that Msps is a strong modifier of CLASP and Abl in the retina. Moreover, we show that Msps functions during axon guidance and antagonizes both CLASP and Abl activity. Our data suggest a model in which CLASP and Msps converge in an antagonistic balance in the Abl signaling pathway.
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Civelekoglu-Scholey G, Tao L, Brust-Mascher I, Wollman R, Scholey JM. Prometaphase spindle maintenance by an antagonistic motor-dependent force balance made robust by a disassembling lamin-B envelope. ACTA ACUST UNITED AC 2010; 188:49-68. [PMID: 20065089 PMCID: PMC2812851 DOI: 10.1083/jcb.200908150] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We tested the classical hypothesis that astral, prometaphase bipolar mitotic spindles are maintained by balanced outward and inward forces exerted on spindle poles by kinesin-5 and -14 using modeling of in vitro and in vivo data from Drosophila melanogaster embryos. Throughout prometaphase, puncta of both motors aligned on interpolar microtubules (MTs [ipMTs]), and motor perturbation changed spindle length, as predicted. Competitive motility of purified kinesin-5 and -14 was well described by a stochastic, opposing power stroke model incorporating motor kinetics and load-dependent detachment. Motor parameters from this model were applied to a new stochastic force-balance model for prometaphase spindles, providing a good fit to data from embryos. Maintenance of virtual spindles required dynamic ipMTs and a narrow range of kinesin-5 to kinesin-14 ratios matching that found in embryos. Functional perturbation and modeling suggest that this range can be extended significantly by a disassembling lamin-B envelope that surrounds the prometaphase spindle and augments the finely tuned, antagonistic kinesin force balance to maintain robust prometaphase spindles as MTs assemble and chromosomes are pushed to the equator.
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Affiliation(s)
- Gul Civelekoglu-Scholey
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
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Abstract
The Drosophila S2 cell line is popularly used to study mitosis. In this cell line, multiple genes can be easily and efficiently knocked down by RNA interference (RNAi), and the associated mitotic phenotypes can be assessed with high-resolution microscopy after immunofluorescence or in a living cell. However, compared to untransformed cells in wild-type organisms such as yeasts or worms, mitosis in the S2 cell line is more variable and often looks abnormal even in RNAi-untreated cells. Therefore, in order to judge whether a phenotype is derived from RNAi of the target gene or is simply a variation of control cells, it is critical to prepare proper control samples and perform objective imaging and image analysis. Here, we discuss how bona fide mitotic phenotypes associated with RNAi can be identified, avoiding selecting false positives, in S2 cells.
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Affiliation(s)
- Gohta Goshima
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
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Gouveia SM, Akhmanova A. Cell and Molecular Biology of Microtubule Plus End Tracking Proteins. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 285:1-74. [DOI: 10.1016/b978-0-12-381047-2.00001-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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50
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Bucciarelli E, Pellacani C, Naim V, Palena A, Gatti M, Somma MP. Drosophila Dgt6 Interacts with Ndc80, Msps/XMAP215, and γ-Tubulin to Promote Kinetochore-Driven MT Formation. Curr Biol 2009; 19:1839-45. [DOI: 10.1016/j.cub.2009.09.043] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Revised: 09/07/2009] [Accepted: 09/09/2009] [Indexed: 01/29/2023]
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