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Anjur-Dietrich MI, Gomez Hererra V, Farhadifar R, Wu H, Merta H, Bahmanyar S, Shelley MJ, Needleman DJ. Mechanics of spindle orientation in human mitotic cells is determined by pulling forces on astral microtubules and clustering of cortical dynein. Dev Cell 2024; 59:2429-2442.e4. [PMID: 38866013 DOI: 10.1016/j.devcel.2024.05.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 04/03/2024] [Accepted: 05/17/2024] [Indexed: 06/14/2024]
Abstract
The forces that orient the spindle in human cells remain poorly understood due to a lack of direct mechanical measurements in mammalian systems. We use magnetic tweezers to measure the force on human mitotic spindles. Combining the spindle's measured resistance to rotation, the speed at which it rotates after laser ablating astral microtubules, and estimates of the number of ablated microtubules reveals that each microtubule contacting the cell cortex is subject to ∼5 pN of pulling force, suggesting that each is pulled on by an individual dynein motor. We find that the concentration of dynein at the cell cortex and extent of dynein clustering are key determinants of the spindle's resistance to rotation, with little contribution from cytoplasmic viscosity, which we explain using a biophysically based mathematical model. This work reveals how pulling forces on astral microtubules determine the mechanics of spindle orientation and demonstrates the central role of cortical dynein clustering.
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Affiliation(s)
- Maya I Anjur-Dietrich
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
| | - Vicente Gomez Hererra
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
| | - Reza Farhadifar
- Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
| | - Haiyin Wu
- Department of Physics, Harvard University, Cambridge, MA 02138, USA; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Holly Merta
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Shirin Bahmanyar
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Michael J Shelley
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA; Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
| | - Daniel J Needleman
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA; Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
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2
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Carvalho C, Barbosa DJ, Celestino R, Zanin E, Xavier Carvalho A, Gassmann R. Dynein directs prophase centrosome migration to control the stem cell division axis in the developing Caenorhabditis elegans epidermis. Genetics 2024; 226:iyae005. [PMID: 38213110 DOI: 10.1093/genetics/iyae005] [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: 11/10/2023] [Revised: 11/10/2023] [Accepted: 01/02/2024] [Indexed: 01/13/2024] Open
Abstract
The microtubule motor dynein is critical for the assembly and positioning of mitotic spindles. In Caenorhabditis elegans, these dynein functions have been extensively studied in the early embryo but remain poorly explored in other developmental contexts. Here, we use a hypomorphic dynein mutant to investigate the motor's contribution to asymmetric stem cell-like divisions in the larval epidermis. Live imaging of seam cell divisions that precede formation of the seam syncytium shows that mutant cells properly assemble but frequently misorient their spindle. Misoriented divisions misplace daughter cells from the seam cell row, generate anucleate compartments due to aberrant cytokinesis, and disrupt asymmetric cell fate inheritance. Consequently, the seam becomes disorganized and populated with extra cells that have lost seam identity, leading to fatal epidermal rupture. We show that dynein orients the spindle through the cortical GOA-1Gα-LIN-5NuMA pathway by directing the migration of prophase centrosomes along the anterior-posterior axis. Spindle misorientation in the dynein mutant can be partially rescued by elongating cells, implying that dynein-dependent force generation and cell shape jointly promote correct asymmetric division of epithelial stem cells.
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Affiliation(s)
- Cátia Carvalho
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4200-135, Portugal
- ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto 4050-313, Portugal
| | - Daniel J Barbosa
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4200-135, Portugal
- 1H-Toxrun-One Health Toxicology Research Unit, University Institute of Health Sciences, CESPU, CRL, Gandra 4585-116, Portugal
| | - Ricardo Celestino
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4200-135, Portugal
| | - Esther Zanin
- Department Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen 91058, Germany
| | - Ana Xavier Carvalho
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4200-135, Portugal
| | - Reto Gassmann
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4200-135, Portugal
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3
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Linehan JB, Edwards GA, Boudreau V, Maddox AS, Maddox PS. Model-based trajectory classification of anchored molecular motor-biopolymer interactions. BIOPHYSICAL REPORTS 2023; 3:100130. [PMID: 37811483 PMCID: PMC10558742 DOI: 10.1016/j.bpr.2023.100130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 09/08/2023] [Indexed: 10/10/2023]
Abstract
During zygotic mitosis in many species, forces generated at the cell cortex are required for the separation and migration of paternally provided centrosomes, pronuclear migration, segregation of genetic material, and cell division. Furthermore, in some species, force-generating interactions between spindle microtubules and the cortex position the mitotic spindle asymmetrically within the zygote, an essential step in asymmetric cell division. Understanding the mechanical and molecular mechanisms of microtubule-dependent force generation and therefore asymmetric cell division requires identification of individual cortical force-generating units in vivo. There is no current method for identifying individual force-generating units with high spatiotemporal resolution. Here, we present a method to determine both the location and the relative number of microtubule-dependent cortical force-generating units using single-molecule imaging of fluorescently labeled dynein. Dynein behavior is modeled to classify trajectories of cortically bound dynein according to whether they are interacting with a microtubule. The categorization strategy recapitulates well-known force asymmetries in C. elegans zygote mitosis. To evaluate the robustness of categorization, we used RNAi to deplete the tubulin subunit TBA-2. As predicted, this treatment reduced the number of trajectories categorized as engaged with a microtubule. Our technique will be a valuable tool to define the molecular mechanisms of dynein cortical force generation and its regulation as well as other instances wherein anchored motors interact with biopolymers (e.g., actin, tubulin, DNA).
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Affiliation(s)
- John B. Linehan
- Department of Biology, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina
| | - Gerald Alan Edwards
- Department of Biology, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina
| | - Vincent Boudreau
- Department of Plant and Microbial Biology, University of California-Berkeley, Berkeley, California
- Department of Biochemistry and Biophysics, University of California-San Francisco, San Francisco, California
| | - Amy Shaub Maddox
- Department of Biology, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina
| | - Paul S. Maddox
- Department of Biology, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina
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4
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Anjur-Dietrich MI, Hererra VG, Farhadifar R, Wu H, Merta H, Bahmanyar S, Shelley MJ, Needleman DJ. Clustering of cortical dynein regulates the mechanics of spindle orientation in human mitotic cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.11.557210. [PMID: 37745442 PMCID: PMC10515834 DOI: 10.1101/2023.09.11.557210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The forces which orient the spindle in human cells remain poorly understood due to a lack of direct mechanical measurements in mammalian systems. We use magnetic tweezers to measure the force on human mitotic spindles. Combining the spindle's measured resistance to rotation, the speed it rotates after laser ablating astral microtubules, and estimates of the number of ablated microtubules reveals that each microtubule contacting the cell cortex is subject to ~1 pN of pulling force, suggesting that each is pulled on by an individual dynein motor. We find that the concentration of dynein at the cell cortex and extent of dynein clustering are key determinants of the spindle's resistance to rotation, with little contribution from cytoplasmic viscosity, which we explain using a biophysically based mathematical model. This work reveals how pulling forces on astral microtubules determine the mechanics of spindle orientation and demonstrates the central role of cortical dynein clustering.
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Affiliation(s)
- Maya I. Anjur-Dietrich
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Vicente Gomez Hererra
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
| | - Reza Farhadifar
- Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
| | - Haiyin Wu
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Holly Merta
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Shirin Bahmanyar
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Michael J. Shelley
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
- Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
| | - Daniel J. Needleman
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
- Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
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5
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Faienza F, Polverino F, Rajendraprasad G, Milletti G, Hu Z, Colella B, Gargano D, Strappazzon F, Rizza S, Vistesen MV, Luo Y, Antonioli M, Cianfanelli V, Ferraina C, Fimia GM, Filomeni G, De Zio D, Dengjel J, Barisic M, Guarguaglini G, Di Bartolomeo S, Cecconi F. AMBRA1 phosphorylation by CDK1 and PLK1 regulates mitotic spindle orientation. Cell Mol Life Sci 2023; 80:251. [PMID: 37584777 PMCID: PMC10432340 DOI: 10.1007/s00018-023-04878-6] [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: 12/31/2022] [Revised: 06/27/2023] [Accepted: 07/17/2023] [Indexed: 08/17/2023]
Abstract
AMBRA1 is a crucial factor for nervous system development, and its function has been mainly associated with autophagy. It has been also linked to cell proliferation control, through its ability to regulate c-Myc and D-type cyclins protein levels, thus regulating G1-S transition. However, it remains still unknown whether AMBRA1 is differentially regulated during the cell cycle, and if this pro-autophagy protein exerts a direct role in controlling mitosis too. Here we show that AMBRA1 is phosphorylated during mitosis on multiple sites by CDK1 and PLK1, two mitotic kinases. Moreover, we demonstrate that AMBRA1 phosphorylation at mitosis is required for a proper spindle function and orientation, driven by NUMA1 protein. Indeed, we show that the localization and/or dynamics of NUMA1 are strictly dependent on AMBRA1 presence, phosphorylation and binding ability. Since spindle orientation is critical for tissue morphogenesis and differentiation, our findings could account for an additional role of AMBRA1 in development and cancer ontogenesis.
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Affiliation(s)
- Fiorella Faienza
- Cell Stress and Survival Group, Center for Autophagy, Recycling and Disease (CARD), Danish Cancer Institute, Copenhagen, Denmark
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - Federica Polverino
- Institute of Molecular Biology and Pathology, CNR National Research Council, Rome, Italy
| | | | - Giacomo Milletti
- Department of Pediatric Hemato-Oncology and Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
- DNA Replication and Cancer Group, Danish Cancer Institute, 2100, Copenhagen, Denmark
| | - Zehan Hu
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Barbara Colella
- Department of Biosciences and Territory, University of Molise, Pesche, Italy
| | - Deborah Gargano
- Department of Biosciences and Territory, University of Molise, Pesche, Italy
| | - Flavie Strappazzon
- IRCCS Fondazione Santa Lucia, Rome, Italy
- Physiopathologie et Génétique du Neurone et du Muscle, UMR5261, U1315, Institut NeuroMyogène, Univ Lyon, Univ Lyon 1, CNRS, INSERM, 69008, Lyon, France
| | - Salvatore Rizza
- Redox Biology Group, Danish Cancer Institute, Copenhagen, Denmark
| | - Mette Vixø Vistesen
- Cell Stress and Survival Group, Center for Autophagy, Recycling and Disease (CARD), Danish Cancer Institute, Copenhagen, Denmark
| | - Yonglun Luo
- Lars Bolund Institute of Regenerative Medicine and Qingdao-Europe Advanced Institute for Life Sciences, BGI Research, Shenzhen, China
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Manuela Antonioli
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
- National Institute for Infectious Diseases, IRCSS "L. Spallanzani", Rome, Italy
| | - Valentina Cianfanelli
- Department of Pediatric Hemato-Oncology and Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
- Department of Science, University "ROMA TRE", 00146, Rome, Italy
- Department of Woman and Child Health and Public Health, Gynecologic Oncology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Caterina Ferraina
- Department of Pediatric Hemato-Oncology and Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Gian Maria Fimia
- National Institute for Infectious Diseases, IRCSS "L. Spallanzani", Rome, Italy
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Giuseppe Filomeni
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
- Redox Biology Group, Danish Cancer Institute, Copenhagen, Denmark
- Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark
| | - Daniela De Zio
- Melanoma Research Team, Danish Cancer Institute, Copenhagen, Denmark
- Department of Drug Design and Pharmacology, University Of Copenhagen, Copenhagen, Denmark
| | - Joern Dengjel
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Marin Barisic
- Cell Division and Cytoskeleton, Danish Cancer Institute, Copenhagen, Denmark
- Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Giulia Guarguaglini
- Institute of Molecular Biology and Pathology, CNR National Research Council, Rome, Italy
| | | | - Francesco Cecconi
- Cell Stress and Survival Group, Center for Autophagy, Recycling and Disease (CARD), Danish Cancer Institute, Copenhagen, Denmark.
- Università Cattolica del Sacro Cuore and Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy.
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6
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Guevara-Garcia A, Soleilhac M, Minc N, Delacour D. Regulation and functions of cell division in the intestinal tissue. Semin Cell Dev Biol 2023:S1084-9521(23)00004-6. [PMID: 36702722 DOI: 10.1016/j.semcdb.2023.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 12/16/2022] [Accepted: 01/06/2023] [Indexed: 01/26/2023]
Abstract
In multicellular organisms, epithelial cells are key elements of tissue organization. In developing epithelial tissues, cellular proliferation and differentiation are under the tight regulation of morphogenetic programs to ensure correct organ formation and functioning. In these processes, proliferation rates and division orientation regulate the speed, timing and direction of tissue expansion but also its proper patterning. Moreover, tissue homeostasis relies on spatio-temporal modulations of daughter cell behavior and arrangement. These aspects are particularly crucial in the intestine, which is one of the most proliferative tissues in adults, making it a very attractive adult organ system to study the role of cell division on epithelial morphogenesis and organ function. Although epithelial cell division has been the subject of intense research for many years in multiple models, it still remains in its infancy in the context of the intestinal tissue. In this review, we focus on the current knowledge on cell division and regulatory mechanisms at play in the intestinal epithelial tissue, as well as their importance in developmental biology and physiopathology.
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Affiliation(s)
| | - Matis Soleilhac
- Université de Paris, CNRS, Institut Jacques Monod, F-75006 Paris, France
| | - Nicolas Minc
- Université de Paris, CNRS, Institut Jacques Monod, F-75006 Paris, France
| | - Delphine Delacour
- Université de Paris, CNRS, Institut Jacques Monod, F-75006 Paris, France.
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7
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Ignacio DP, Kravtsova N, Henry J, Palomares RH, Dawes AT. Dynein localization and pronuclear movement in the C. elegans zygote. Cytoskeleton (Hoboken) 2022; 79:133-143. [PMID: 36214774 PMCID: PMC10092226 DOI: 10.1002/cm.21733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 10/02/2022] [Accepted: 10/04/2022] [Indexed: 01/30/2023]
Abstract
Centrosomes serve as a site for microtubule nucleation and these microtubules will grow and interact with the motor protein dynein at the cortex. The position of the centrosomes determines where the mitotic spindle will develop across all cell types. Centrosome positioning is achieved through dynein and microtubule-mediated force generation. The mechanism and regulation of force generation during centrosome positioning are not fully understood. Centrosome and pronuclear movement in the first cell cycle of the Caenorhabditis elegans early embryo undergoes both centration and rotation prior to cell division. The proteins LET-99 and GPB-1 have been postulated to have a role in force generation associated with pronuclear centration and rotation dynamics. When the expression of these proteins is perturbed, pronuclear positioning exhibits a movement defect characterized by oscillatory ("wobble") behavior of the pronuclear complex (PNC). To determine if this movement defect is due to an effect on cortical dynein distribution, we utilize RNAi-mediated knockdown of LET-99 and GPB-1 to induce wobble and assay for any effects on GFP-tagged dynein localization in the early C. elegans embryo. To compare and quantify the movement defect produced by the knockdown of LET-99 and GPB-1, we devised a quantification method that measures the strength of wobble ("wobble metric") observed under these experimental conditions. Our quantification of pronuclear complex dynamics and dynein localization shows that loss of LET-99 and GPB-1 induces a similar movement defect which is independent of cortical dynein localization in the early C. elegans embryo.
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Affiliation(s)
- David P Ignacio
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio, USA
| | - Natalia Kravtsova
- Department of Mathematics, Ohio State University, Columbus, Ohio, USA
| | - John Henry
- Department of Mathematics, Ohio State University, Columbus, Ohio, USA
| | | | - Adriana T Dawes
- Department of Mathematics, Department of Molecular Genetics, Ohio State University, Columbus, Ohio, USA
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8
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Villaseca S, Romero G, Ruiz MJ, Pérez C, Leal JI, Tovar LM, Torrejón M. Gαi protein subunit: A step toward understanding its non-canonical mechanisms. Front Cell Dev Biol 2022; 10:941870. [PMID: 36092739 PMCID: PMC9449497 DOI: 10.3389/fcell.2022.941870] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/01/2022] [Indexed: 11/13/2022] Open
Abstract
The heterotrimeric G protein family plays essential roles during a varied array of cellular events; thus, its deregulation can seriously alter signaling events and the overall state of the cell. Heterotrimeric G-proteins have three subunits (α, β, γ) and are subdivided into four families, Gαi, Gα12/13, Gαq, and Gαs. These proteins cycle between an inactive Gα-GDP state and active Gα-GTP state, triggered canonically by the G-protein coupled receptor (GPCR) and by other accessory proteins receptors independent also known as AGS (Activators of G-protein Signaling). In this review, we summarize research data specific for the Gαi family. This family has the largest number of individual members, including Gαi1, Gαi2, Gαi3, Gαo, Gαt, Gαg, and Gαz, and constitutes the majority of G proteins α subunits expressed in a tissue or cell. Gαi was initially described by its inhibitory function on adenylyl cyclase activity, decreasing cAMP levels. Interestingly, today Gi family G-protein have been reported to be importantly involved in the immune system function. Here, we discuss the impact of Gαi on non-canonical effector proteins, such as c-Src, ERK1/2, phospholipase-C (PLC), and proteins from the Rho GTPase family members, all of them essential signaling pathways regulating a wide range of physiological processes.
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9
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Hornak I, Rieger H. Stochastic model of T Cell repolarization during target elimination (II). Biophys J 2022; 121:1246-1265. [PMID: 35196513 PMCID: PMC9034251 DOI: 10.1016/j.bpj.2022.02.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/08/2021] [Accepted: 02/16/2022] [Indexed: 11/16/2022] Open
Abstract
Cytotoxic T lymphocytes (T cells) and natural killer cells form a tight contact, the immunological synapse (IS), with target cells, where they release their lytic granules containing perforin/granzyme and cytokine-containing vesicles. During this process the cell repolarizes and moves the microtubule organizing center (MTOC) toward the IS. In the first part of our work we developed a computational model for the molecular-motor-driven motion of the microtubule cytoskeleton during T cell polarization and analyzed the effects of cortical-sliding and capture-shrinkage mechanisms. Here we use this model to analyze the dynamics of the MTOC repositioning in situations in which 1) the IS is in an arbitrary position with respect to the initial position of the MTOC and 2) the T cell has two IS at two arbitrary positions. In the case of one IS, we found that the initial position determines which mechanism is dominant and that the time of repositioning does not rise monotonously with the MTOC-IS distance. In the case of two IS, we observe several scenarios that have also been reported experimentally: the MTOC alternates stochastically (but with a well-defined average transition time) between the two IS; it wiggles in between the two IS without transiting to one of the two; or it is at some point pulled to one of the two IS and stays there. Our model allows one to predict which scenario emerges in dependency of the mechanisms in action and the number of dyneins present. We report that the presence of capture-shrinkage mechanism in at least one IS is necessary to assure the transitions in every cell configuration. Moreover, the frequency of transitions does not decrease with the distance between the two IS and is the highest when both mechanisms are present in both IS.
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Affiliation(s)
- Ivan Hornak
- Department of Theoretical Physics, Center for Biophysics, Saarland University, Saarbrücken, Germany.
| | - Heiko Rieger
- Department of Theoretical Physics, Center for Biophysics, Saarland University, Saarbrücken, Germany
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10
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Lacroix B, Dumont J. Spatial and Temporal Scaling of Microtubules and Mitotic Spindles. Cells 2022; 11:cells11020248. [PMID: 35053364 PMCID: PMC8774166 DOI: 10.3390/cells11020248] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/07/2022] [Accepted: 01/09/2022] [Indexed: 02/01/2023] Open
Abstract
During cell division, the mitotic spindle, a macromolecular structure primarily comprised of microtubules, drives chromosome alignment and partitioning between daughter cells. Mitotic spindles can sense cellular dimensions in order to adapt their length and mass to cell size. This scaling capacity is particularly remarkable during early embryo cleavage when cells divide rapidly in the absence of cell growth, thus leading to a reduction of cell volume at each division. Although mitotic spindle size scaling can occur over an order of magnitude in early embryos, in many species the duration of mitosis is relatively short, constant throughout early development and independent of cell size. Therefore, a key challenge for cells during embryo cleavage is not only to assemble a spindle of proper size, but also to do it in an appropriate time window which is compatible with embryo development. How spatial and temporal scaling of the mitotic spindle is achieved and coordinated with the duration of mitosis remains elusive. In this review, we will focus on the mechanisms that support mitotic spindle spatial and temporal scaling over a wide range of cell sizes and cellular contexts. We will present current models and propose alternative mechanisms allowing cells to spatially and temporally coordinate microtubule and mitotic spindle assembly.
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Affiliation(s)
- Benjamin Lacroix
- Centre de Recherche de Biologie Cellulaire de Montpellier (CRBM), CNRS UMR 5237, Université de Montpellier, 1919 Route de Mende, CEDEX 5, 34293 Montpellier, France
- Correspondence:
| | - Julien Dumont
- Université de Paris, CNRS, Institut Jacques Monod, F-75013 Paris, France;
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11
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Bouvrais H, Chesneau L, Le Cunff Y, Fairbrass D, Soler N, Pastezeur S, Pécot T, Kervrann C, Pécréaux J. The coordination of spindle-positioning forces during the asymmetric division of the Caenorhabditis elegans zygote. EMBO Rep 2021; 22:e50770. [PMID: 33900015 DOI: 10.15252/embr.202050770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 02/22/2021] [Accepted: 03/03/2021] [Indexed: 12/28/2022] Open
Abstract
In Caenorhabditis elegans zygote, astral microtubules generate forces essential to position the mitotic spindle, by pushing against and pulling from the cortex. Measuring microtubule dynamics there, we revealed the presence of two populations, corresponding to pulling and pushing events. It offers a unique opportunity to study, under physiological conditions, the variations of both spindle-positioning forces along space and time. We propose a threefold control of pulling force, by polarity, spindle position and mitotic progression. We showed that the sole anteroposterior asymmetry in dynein on-rate, encoding pulling force imbalance, is sufficient to cause posterior spindle displacement. The positional regulation, reflecting the number of microtubule contacts in the posterior-most region, reinforces this imbalance only in late anaphase. Furthermore, we exhibited the first direct proof that dynein processivity increases along mitosis. It reflects the temporal control of pulling forces, which strengthens at anaphase onset following mitotic progression and independently from chromatid separation. In contrast, the pushing force remains constant and symmetric and contributes to maintaining the spindle at the cell centre during metaphase.
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Affiliation(s)
| | | | - Yann Le Cunff
- CNRS, IGDR - UMR 6290, University of Rennes, Rennes, France
| | | | - Nina Soler
- CNRS, IGDR - UMR 6290, University of Rennes, Rennes, France
| | | | - Thierry Pécot
- INRIA, Centre Rennes - Bretagne Atlantique, Rennes, France
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12
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Omer S, Brock K, Beckford J, Lee WL. Overexpression of Mdm36 reveals Num1 foci that mediate dynein-dependent microtubule sliding in budding yeast. J Cell Sci 2020; 133:jcs246363. [PMID: 32938686 PMCID: PMC7578358 DOI: 10.1242/jcs.246363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 09/01/2020] [Indexed: 01/21/2023] Open
Abstract
The current model for spindle positioning requires attachment of the microtubule (MT) motor cytoplasmic dynein to the cell cortex, where it generates pulling force on astral MTs to effect spindle displacement. How dynein is anchored by cortical attachment machinery to generate large spindle-pulling forces remains unclear. Here, we show that cortical clustering of Num1, the yeast dynein attachment molecule, is limited by its assembly factor Mdm36. Overexpression of Mdm36 results in an overall enhancement of Num1 clustering but reveals a population of dim Num1 clusters that mediate dynein anchoring at the cell cortex. Direct imaging shows that bud-localized, dim Num1 clusters containing around only six Num1 molecules mediate dynein-dependent spindle pulling via a lateral MT sliding mechanism. Mutations affecting Num1 clustering interfere with mitochondrial tethering but do not interfere with the dynein-based spindle-pulling function of Num1. We propose that formation of small ensembles of attachment molecules is sufficient for dynein anchorage and cortical generation of large spindle-pulling forces.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Safia Omer
- Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA
| | - Katia Brock
- Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA
| | - John Beckford
- Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA
| | - Wei-Lih Lee
- Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA
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13
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Gubieda AG, Packer JR, Squires I, Martin J, Rodriguez J. Going with the flow: insights from Caenorhabditis elegans zygote polarization. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190555. [PMID: 32829680 PMCID: PMC7482210 DOI: 10.1098/rstb.2019.0555] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/09/2020] [Indexed: 12/12/2022] Open
Abstract
Cell polarity is the asymmetric distribution of cellular components along a defined axis. Polarity relies on complex signalling networks between conserved patterning proteins, including the PAR (partitioning defective) proteins, which become segregated in response to upstream symmetry breaking cues. Although the mechanisms that drive the asymmetric localization of these proteins are dependent upon cell type and context, in many cases the regulation of actomyosin cytoskeleton dynamics is central to the transport, recruitment and/or stabilization of these polarity effectors into defined subcellular domains. The transport or advection of PAR proteins by an actomyosin flow was first observed in the Caenorhabditis elegans zygote more than a decade ago. Since then a multifaceted approach, using molecular methods, high-throughput screens, and biophysical and computational models, has revealed further aspects of this flow and how polarity regulators respond to and modulate it. Here, we review recent findings on the interplay between actomyosin flow and the PAR patterning networks in the polarization of the C. elegans zygote. We also discuss how these discoveries and developed methods are shaping our understanding of other flow-dependent polarizing systems. This article is part of a discussion meeting issue 'Contemporary morphogenesis'.
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Affiliation(s)
| | | | | | | | - Josana Rodriguez
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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14
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Wavreil FDM, Yajima M. Diversity of activator of G-protein signaling (AGS)-family proteins and their impact on asymmetric cell division across taxa. Dev Biol 2020; 465:89-99. [PMID: 32687894 DOI: 10.1016/j.ydbio.2020.07.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/05/2020] [Accepted: 07/06/2020] [Indexed: 11/18/2022]
Abstract
Asymmetric cell division (ACD) is a cellular process that forms two different cell types through a cell division and is thus critical for the development of all multicellular organisms. Not all but many of the ACD processes are mediated by proper orientation of the mitotic spindle, which segregates the fate determinants asymmetrically into daughter cells. In many cell types, the evolutionarily conserved protein complex of Gαi/AGS-family protein/NuMA-like protein appears to play critical roles in orienting the spindle and/or generating the polarized cortical forces to regulate ACD. Studies in various organisms reveal that this conserved protein complex is slightly modified in each phylum or even within species. In particular, AGS-family proteins appear to be modified with a variable number of motifs in their functional domains across taxa. This apparently creates different molecular interactions and mechanisms of ACD in each developmental program, ultimately contributing to developmental diversity across species. In this review, we discuss how a conserved ACD machinery has been modified in each phylum over the course of evolution with a major focus on the molecular evolution of AGS-family proteins and its impact on ACD regulation.
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Affiliation(s)
- Florence D M Wavreil
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, 02906, USA
| | - Mamiko Yajima
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, 02906, USA.
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15
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Torisawa T, Kimura A. The Generation of Dynein Networks by Multi-Layered Regulation and Their Implication in Cell Division. Front Cell Dev Biol 2020; 8:22. [PMID: 32083077 PMCID: PMC7004958 DOI: 10.3389/fcell.2020.00022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 01/13/2020] [Indexed: 12/13/2022] Open
Abstract
Cytoplasmic dynein-1 (hereafter referred to as dynein) is a major microtubule-based motor critical for cell division. Dynein is essential for the formation and positioning of the mitotic spindle as well as the transport of various cargos in the cell. A striking feature of dynein is that, despite having a wide variety of functions, the catalytic subunit is coded in a single gene. To perform various cellular activities, there seem to be different types of dynein that share a common catalytic subunit. In this review, we will refer to the different kinds of dynein as “dyneins.” This review attempts to classify the mechanisms underlying the emergence of multiple dyneins into four layers. Inside a cell, multiple dyneins generated through the multi-layered regulations interact with each other to form a network of dyneins. These dynein networks may be responsible for the accurate regulation of cellular activities, including cell division. How these networks function inside a cell, with a focus on the early embryogenesis of Caenorhabditis elegans embryos, is discussed, as well as future directions for the integration of our understanding of molecular layering to understand the totality of dynein’s function in living cells.
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Affiliation(s)
- Takayuki Torisawa
- Cell Architecture Laboratory, National Institute of Genetics, Mishima, Japan.,Department of Genetics, The Graduate University for Advanced Studies, SOKENDAI, Mishima, Japan
| | - Akatsuki Kimura
- Cell Architecture Laboratory, National Institute of Genetics, Mishima, Japan.,Department of Genetics, The Graduate University for Advanced Studies, SOKENDAI, Mishima, Japan
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16
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Bondaz A, Cirillo L, Meraldi P, Gotta M. Cell polarity-dependent centrosome separation in the C. elegans embryo. J Cell Biol 2019; 218:4112-4126. [PMID: 31645459 PMCID: PMC6891102 DOI: 10.1083/jcb.201902109] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 07/10/2019] [Accepted: 09/06/2019] [Indexed: 12/30/2022] Open
Abstract
Bondaz et al. show that in C. elegans embryos, the microtubule depolymerase KLP-7/MCAK is required for efficient centrosome separation in the somatic AB cell, but not the germline P1 cell. This difference in spindle assembly depends on cell polarity via the mitotic kinase PLK1. In animal cells, faithful chromosome segregation depends on the assembly of a bipolar spindle driven by the timely separation of the two centrosomes. Here we took advantage of the highly stereotypical cell divisions in Caenorhabditis elegans embryos to identify new regulators of centrosome separation. We find that at the two-cell stage, the somatic AB cell initiates centrosome separation later than the germline P1 cell. This difference is strongly exacerbated by the depletion of the kinesin-13 KLP-7/MCAK, resulting in incomplete centrosome separation at NEBD in AB but not P1. Our genetic and cell biology data indicate that this phenotype depends on cell polarity via the enrichment in AB of the mitotic kinase PLK-1, which itself limits the cortical localization of the dynein-binding NuMA orthologue LIN-5. We postulate that the timely separation of centrosomes is regulated in a cell type–dependent manner.
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Affiliation(s)
- Alexandra Bondaz
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Luca Cirillo
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Patrick Meraldi
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland .,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Monica Gotta
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland .,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Swiss National Centre for Competence in Research in Chemical Biology, University of Geneva, Geneva, Switzerland
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17
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van Leen EV, di Pietro F, Bellaïche Y. Oriented cell divisions in epithelia: from force generation to force anisotropy by tension, shape and vertices. Curr Opin Cell Biol 2019; 62:9-16. [PMID: 31509787 DOI: 10.1016/j.ceb.2019.07.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 07/25/2019] [Accepted: 07/26/2019] [Indexed: 01/01/2023]
Abstract
Mitotic spindle orientation has been linked to asymmetric cell divisions, tissue morphogenesis and homeostasis. The canonical pathway to orient the mitotic spindle is composed of the cortical recruitment factor NuMA and the molecular motor dynein, which exerts pulling forces on astral microtubules to orient the spindle. Recent work has defined a novel role for NuMA as a direct contributor to force generation. In addition, the exploration of geometrical and physical cues combined with the study of classical polarity pathways has led to deeper insights into the upstream regulation of spindle orientation. Here, we focus on how cell shape, junctions and mechanical tension act to orient spindle pulling forces in epithelia, and discuss different roles for spindle orientation in epithelia.
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Affiliation(s)
- Eric Victor van Leen
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, F-75248 Paris Cedex 05, France; Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 3215, INSERM U934, F-75005, France
| | - Florencia di Pietro
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, F-75248 Paris Cedex 05, France; Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 3215, INSERM U934, F-75005, France
| | - Yohanns Bellaïche
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, F-75248 Paris Cedex 05, France; Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 3215, INSERM U934, F-75005, France.
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18
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Freeman S, Mateo Sánchez S, Pouyo R, Van Lerberghe P, Hanon K, Thelen N, Thiry M, Morelli G, Van Hees L, Laguesse S, Chariot A, Nguyen L, Delacroix L, Malgrange B. Proteostasis is essential during cochlear development for neuron survival and hair cell polarity. EMBO Rep 2019; 20:e47097. [PMID: 31321879 PMCID: PMC6726910 DOI: 10.15252/embr.201847097] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 06/13/2019] [Accepted: 06/22/2019] [Indexed: 01/23/2023] Open
Abstract
Protein homeostasis is essential to cell function, and a compromised ability to reduce the load of misfolded and aggregated proteins is linked to numerous age-related diseases, including hearing loss. Here, we show that altered proteostasis consequent to Elongator complex deficiency also impacts the proper development of the cochlea and results in deafness. In the absence of the catalytic subunit Elp3, differentiating spiral ganglion neurons display large aggresome-like structures and undergo apoptosis before birth. The cochlear mechanosensory cells are able to survive proteostasis disruption but suffer defects in polarity and stereociliary bundle morphogenesis. We demonstrate that protein aggregates accumulate at the apical surface of hair cells, where they cause a local slowdown of microtubular trafficking, altering the distribution of intrinsic polarity proteins and affecting kinocilium position and length. Alleviation of protein misfolding using the chemical chaperone 4-phenylbutyric acid during embryonic development ameliorates hair cell polarity in Elp3-deficient animals. Our study highlights the importance of developmental proteostasis in the cochlea and unveils an unexpected link between proteome integrity and polarized organization of cellular components.
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Affiliation(s)
- Stephen Freeman
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
| | - Susana Mateo Sánchez
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
| | - Ronald Pouyo
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
| | - Pierre‐Bernard Van Lerberghe
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
| | - Kevin Hanon
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
| | - Nicolas Thelen
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
| | - Marc Thiry
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
| | - Giovanni Morelli
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
- UHasseltBIOMEDHasseltBelgium
| | - Laura Van Hees
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
| | - Sophie Laguesse
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
| | - Alain Chariot
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
- GIGA‐Molecular Biology of DiseasesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
- Walloon Excellence in Life Sciences and Biotechnology (WELBIO)WavreBelgium
| | - Laurent Nguyen
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
| | - Laurence Delacroix
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
| | - Brigitte Malgrange
- GIGA‐NeurosciencesInterdisciplinary Cluster for Applied Genoproteomics (GIGA‐R)C.H.U. Sart TilmanUniversity of LiègeLiègeBelgium
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19
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Kotak S. Mechanisms of Spindle Positioning: Lessons from Worms and Mammalian Cells. Biomolecules 2019; 9:E80. [PMID: 30823600 PMCID: PMC6406873 DOI: 10.3390/biom9020080] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 02/13/2019] [Accepted: 02/18/2019] [Indexed: 02/06/2023] Open
Abstract
Proper positioning of the mitotic spindle is fundamental for specifying the site for cleavage furrow, and thus regulates the appropriate sizes and accurate distribution of the cell fate determinants in the resulting daughter cells during development and in the stem cells. The past couple of years have witnessed tremendous work accomplished in the area of spindle positioning, and this has led to the emergence of a working model unravelling in-depth mechanistic insight of the underlying process orchestrating spindle positioning. It is evident now that the correct positioning of the mitotic spindle is not only guided by the chemical cues (protein⁻protein interactions) but also influenced by the physical nature of the cellular environment. In metazoans, the key players that regulate proper spindle positioning are the actin-rich cell cortex and associated proteins, the ternary complex (Gα/GPR-1/2/LIN-5 in Caenorhabditis elegans, Gαi/Pins/Mud in Drosophila and Gαi1-3/LGN/NuMA in humans), minus-end-directed motor protein dynein and the cortical machinery containing myosin. In this review, I will mainly discuss how the abovementioned components precisely and spatiotemporally regulate spindle positioning by sensing the physicochemical environment for execution of flawless mitosis.
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Affiliation(s)
- Sachin Kotak
- Department of Microbiology and Cell Biology (MCB), Indian Institute of Science (IISc), Bangalore 560012, India.
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20
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G Proteins and GPCRs in C. elegans Development: A Story of Mutual Infidelity. J Dev Biol 2018; 6:jdb6040028. [PMID: 30477278 PMCID: PMC6316442 DOI: 10.3390/jdb6040028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 11/15/2018] [Accepted: 11/22/2018] [Indexed: 12/14/2022] Open
Abstract
Many vital processes during C. elegans development, especially the establishment and maintenance of cell polarity in embryogenesis, are controlled by complex signaling pathways. G protein-coupled receptors (GPCRs), such as the four Frizzled family Wnt receptors, are linchpins in regulating and orchestrating several of these mechanisms. However, despite being GPCRs, which usually couple to G proteins, these receptors do not seem to activate classical heterotrimeric G protein-mediated signaling cascades. The view on signaling during embryogenesis is further complicated by the fact that heterotrimeric G proteins do play essential roles in cell polarity during embryogenesis, but their activity is modulated in a predominantly GPCR-independent manner via G protein regulators such as GEFs GAPs and GDIs. Further, the triggered downstream effectors are not typical. Only very few GPCR-dependent and G protein-mediated signaling pathways have been unambiguously defined in this context. This unusual and highly intriguing concept of separating GPCR function and G-protein activity, which is not restricted to embryogenesis in C. elegans but can also be found in other organisms, allows for essential and multi-faceted ways of regulating cellular communication and response. Although its relevance cannot be debated, its impact is still poorly discussed, and C. elegans is an ideal model to understand the underlying principles.
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21
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Greenberg SR, Tan W, Lee WL. Num1 versus NuMA: insights from two functionally homologous proteins. Biophys Rev 2018; 10:1631-1636. [PMID: 30402673 PMCID: PMC6297085 DOI: 10.1007/s12551-018-0472-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 10/21/2018] [Indexed: 12/19/2022] Open
Abstract
In both animals and fungi, spindle positioning is dependent upon pulling forces generated by cortically anchored dynein. In animals, cortical anchoring is accomplished by a ternary complex containing the dynein-binding protein NuMA and its cortical attachment machinery. The same function is accomplished by Num1 in budding yeast. While not homologous in primary sequence, NuMA and Num1 appear to share striking similarities in their mechanism of function. Here, we discuss evidence supporting that Num1 in fungi is a functional homolog of NuMA due to their similarity in domain organization and role in the generation of cortical pulling forces.
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Affiliation(s)
- Samuel R Greenberg
- Department of Biological Sciences, Dartmouth College, Hanover, NH, 03755, USA
| | - Weimin Tan
- Department of Biological Sciences, Dartmouth College, Hanover, NH, 03755, USA
| | - Wei-Lih Lee
- Department of Biological Sciences, Dartmouth College, Hanover, NH, 03755, USA.
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22
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Omer S, Greenberg SR, Lee WL. Cortical dynein pulling mechanism is regulated by differentially targeted attachment molecule Num1. eLife 2018; 7:36745. [PMID: 30084355 PMCID: PMC6080947 DOI: 10.7554/elife.36745] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 07/05/2018] [Indexed: 12/17/2022] Open
Abstract
Cortical dynein generates pulling forces via microtubule (MT) end capture-shrinkage and lateral MT sliding mechanisms. In Saccharomyces cerevisiae, the dynein attachment molecule Num1 interacts with endoplasmic reticulum (ER) and mitochondria to facilitate spindle positioning across the mother-bud neck, but direct evidence for how these cortical contacts regulate dynein-dependent pulling forces is lacking. We show that loss of Scs2/Scs22, ER tethering proteins, resulted in defective Num1 distribution and loss of dynein-dependent MT sliding, the hallmark of dynein function. Cells lacking Scs2/Scs22 performed spindle positioning via MT end capture-shrinkage mechanism, requiring dynein anchorage to an ER- and mitochondria-independent population of Num1, dynein motor activity, and CAP-Gly domain of dynactin Nip100/p150Glued subunit. Additionally, a CAAX-targeted Num1 rescued loss of lateral patches and MT sliding in the absence of Scs2/Scs22. These results reveal distinct populations of Num1 and underline the importance of their spatial distribution as a critical factor for regulating dynein pulling force. Cells must divide so that organisms can grow, repair damaged tissues or reproduce. Before dividing, a cell creates two identical copies of its genetic information – one for each daughter. A molecular machine known as the mitotic spindle then moves each set of genetic material to where it will be needed when the daughter cells form. For the process to work properly, however, a motor protein known as dynein must correctly position the spindle by pulling it into place from the outskirts of the cell. When a baker’s yeast cell divides, it first forms a ‘bump’, which grows into a bud that will ultimately become another yeast. The spindle needs to be precisely placed at the midpoint between the original cell and the bud, so the genetic material can get into the future daughter cell. To do so, dynein travels to the bud, where a protein called Num1 helps it attach to the periphery and pull the filaments of the mitotic spindle (known as microtubules) to the correct position. Num1 also attaches to other cellular structures in the bud, including one known as the endoplasmic reticulum. It was unclear how this connection changes where dynein is located, and how it can pull on the spindle. To study this, Omer et al. labeled Num1, dynein and microtubules with fluorescent markers so they could be followed in living baker’s yeast using time-lapse microscopy. Mutant yeast strains were also used to disrupt how these proteins associate, which helps to tease out their roles. The experiments show that there are several populations of Num1 in the bud. One associates with the endoplasmic reticulum, and it helps dynein grab the side of a microtubule and make it slide into the bud. The other does not attach to the reticulum, but instead is located at the very tip of the bud. There, it makes dynein capture the end of the microtubule; this destabilizes the filament, which starts to shorten. As the microtubule shrinks, the spindle is pulled closer to the bud’s tip, which aligns it in the right position. The yeast cells thus need Num1 in both locations to fine-tune the pulling activity of dynein, and the spindle’s final positioning. In the human body, not all divisions create two identical cells; for example, the daughters of stem cells can have different fates. This is due to a precise asymmetric division which dynein partly controls. The results by Omer et al. could help to unravel this mechanism.
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Affiliation(s)
- Safia Omer
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, United States
| | - Samuel R Greenberg
- Department of Biological Sciences, Dartmouth College, Hanover, United States
| | - Wei-Lih Lee
- Department of Biological Sciences, Dartmouth College, Hanover, United States
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23
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Heppert JK, Pani AM, Roberts AM, Dickinson DJ, Goldstein B. A CRISPR Tagging-Based Screen Reveals Localized Players in Wnt-Directed Asymmetric Cell Division. Genetics 2018; 208:1147-1164. [PMID: 29348144 PMCID: PMC5844328 DOI: 10.1534/genetics.117.300487] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 01/08/2018] [Indexed: 11/18/2022] Open
Abstract
Oriented cell divisions are critical to establish and maintain cell fates and tissue organization. Diverse extracellular and intracellular cues have been shown to provide spatial information for mitotic spindle positioning; however, the molecular mechanisms by which extracellular signals communicate with cells to direct mitotic spindle positioning are largely unknown. In animal cells, oriented cell divisions are often achieved by the localization of force-generating motor protein complexes to discrete cortical domains. Disrupting either these force-generating complexes or proteins that globally affect microtubule stability results in defects in mitotic positioning, irrespective of whether these proteins function as spatial cues for spindle orientation. This poses a challenge to traditional genetic dissection of this process. Therefore, as an alternative strategy to identify key proteins that act downstream of intercellular signaling, we screened the localization of many candidate proteins by inserting fluorescent tags directly into endogenous gene loci, without overexpressing the proteins. We tagged 23 candidate proteins in Caenorhabditis elegans and examined each protein's localization in a well-characterized, oriented cell division in the four-cell-stage embryo. We used cell manipulations and genetic experiments to determine which cells harbor key localized proteins and which signals direct these localizations in vivo We found that Dishevelled and adenomatous polyposis coli homologs are polarized during this oriented cell division in response to a Wnt signal, but two proteins typically associated with mitotic spindle positioning, homologs of NuMA and Dynein, were not detectably polarized. These results suggest an unexpected mechanism for mitotic spindle positioning in this system, they pinpoint key proteins of interest, and they highlight the utility of a screening approach based on analyzing the localization of endogenously tagged proteins.
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Affiliation(s)
- Jennifer K Heppert
- Department of Biology, University of North Carolina at Chapel Hill, North Carolina 27599
| | - Ariel M Pani
- Department of Biology, University of North Carolina at Chapel Hill, North Carolina 27599
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, North Carolina 27599
| | - Allyson M Roberts
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, North Carolina 27599
| | - Daniel J Dickinson
- Department of Biology, University of North Carolina at Chapel Hill, North Carolina 27599
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, North Carolina 27599
| | - Bob Goldstein
- Department of Biology, University of North Carolina at Chapel Hill, North Carolina 27599
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, North Carolina 27599
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, North Carolina 27599
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24
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Howard J, Garzon-Coral C. Physical Limits on the Precision of Mitotic Spindle Positioning by Microtubule Pushing forces: Mechanics of mitotic spindle positioning. Bioessays 2017; 39:10.1002/bies.201700122. [PMID: 28960439 PMCID: PMC5698852 DOI: 10.1002/bies.201700122] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 08/13/2017] [Indexed: 01/07/2023]
Abstract
Tissues are shaped and patterned by mechanical and chemical processes. A key mechanical process is the positioning of the mitotic spindle, which determines the size and location of the daughter cells within the tissue. Recent force and position-fluctuation measurements indicate that pushing forces, mediated by the polymerization of astral microtubules against- the cell cortex, maintain the mitotic spindle at the cell center in Caenorhabditis elegans embryos. The magnitude of the centering forces suggests that the physical limit on the accuracy and precision of this centering mechanism is determined by the number of pushing microtubules rather than by thermally driven fluctuations. In cells that divide asymmetrically, anti-centering, pulling forces generated by cortically located dyneins, in conjunction with microtubule depolymerization, oppose the pushing forces to drive spindle displacements away from the center. Thus, a balance of centering pushing forces and anti-centering pulling forces localize the mitotic spindles within dividing C. elegans cells.
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Affiliation(s)
- Jonathon Howard
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Carlos Garzon-Coral
- Shriram Center for Chemical Engineering & Bioengineering, Stanford University, CA 94305, USA
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25
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Costache V, Hebras C, Pruliere G, Besnardeau L, Failla M, Copley RR, Burgess D, Chenevert J, McDougall A. Kif2 localizes to a subdomain of cortical endoplasmic reticulum that drives asymmetric spindle position. Nat Commun 2017; 8:917. [PMID: 29030551 PMCID: PMC5640700 DOI: 10.1038/s41467-017-01048-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 08/16/2017] [Indexed: 12/22/2022] Open
Abstract
Asymmetric positioning of the mitotic spindle is a fundamental process responsible for creating sibling cell size asymmetry; however, how the cortex causes the depolymerization of astral microtubules during asymmetric spindle positioning has remained elusive. Early ascidian embryos possess a large cortical subdomain of endoplasmic reticulum (ER) that causes asymmetric spindle positioning driving unequal cell division. Here we show that the microtubule depolymerase Kif2 localizes to this subdomain of cortical ER. Rapid live-cell imaging reveals that microtubules are less abundant in the subdomain of cortical ER. Inhibition of Kif2 function prevents the development of mitotic aster asymmetry and spindle pole movement towards the subdomain of cortical ER, whereas locally increasing microtubule depolymerization causes exaggerated asymmetric spindle positioning. This study shows that the microtubule depolymerase Kif2 is localized to a cortical subdomain of endoplasmic reticulum that is involved in asymmetric spindle positioning during unequal cell division. Early ascidian embryos have a cortical subdomain of endoplasmic reticulum (ER) that controls asymmetric spindle positioning driving unequal cell division. Here the authors show that the microtubule depolymerase Kif2 is localized to a cortical subdomain of the ER that is involved in asymmetric spindle positioning.
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Affiliation(s)
- Vlad Costache
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Observatoire Océanologique, Villefranche sur-mer, 06230, France
| | - Celine Hebras
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Observatoire Océanologique, Villefranche sur-mer, 06230, France
| | - Gerard Pruliere
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Observatoire Océanologique, Villefranche sur-mer, 06230, France
| | - Lydia Besnardeau
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Observatoire Océanologique, Villefranche sur-mer, 06230, France
| | - Margaux Failla
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Observatoire Océanologique, Villefranche sur-mer, 06230, France
| | - Richard R Copley
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Observatoire Océanologique, Villefranche sur-mer, 06230, France
| | - David Burgess
- Boston College, Biology Department, 528 Higgins Hall, 140 Commonwealth Ave, Chestnut Hill, MA, 0246, USA
| | - Janet Chenevert
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Observatoire Océanologique, Villefranche sur-mer, 06230, France.
| | - Alex McDougall
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Observatoire Océanologique, Villefranche sur-mer, 06230, France.
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di Pietro F, Valon L, Li Y, Goïame R, Genovesio A, Morin X. An RNAi Screen in a Novel Model of Oriented Divisions Identifies the Actin-Capping Protein Z β as an Essential Regulator of Spindle Orientation. Curr Biol 2017; 27:2452-2464.e8. [PMID: 28803871 DOI: 10.1016/j.cub.2017.06.055] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 05/06/2017] [Accepted: 06/20/2017] [Indexed: 10/19/2022]
Abstract
Oriented cell divisions are controlled by a conserved molecular cascade involving Gαi, LGN, and NuMA. We developed a new cellular model of oriented cell divisions combining micropatterning and localized recruitment of Gαi and performed an RNAi screen for regulators acting downstream of Gαi. Remarkably, this screen revealed a unique subset of dynein regulators as being essential for spindle orientation, shedding light on a core regulatory aspect of oriented divisions. We further analyze the involvement of one novel regulator, the actin-capping protein CAPZB. Mechanistically, we show that CAPZB controls spindle orientation independently of its classical role in the actin cytoskeleton by regulating the assembly, stability, and motor activity of the dynein/dynactin complex at the cell cortex, as well as the dynamics of mitotic microtubules. Finally, we show that CAPZB controls planar divisions in vivo in the developing neuroepithelium. This demonstrates the power of this in cellulo model of oriented cell divisions to uncover new genes required in spindle orientation in vertebrates.
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Affiliation(s)
- Florencia di Pietro
- Cell Division and Neurogenesis, IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France; Sorbonne Universités, UPMC Université Paris 06, IFD, 4 Place Jussieu, 75252 Paris, France
| | - Léo Valon
- Laboratoire Physico-Chimie, Institut Curie, PSL Research University, CNRS, UPMC Université Paris 06, 75005 Paris, France
| | - Yingbo Li
- Cell Division and Neurogenesis, IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France; Scientific Center for Computational Biology, IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France
| | - Rosette Goïame
- Cell Division and Neurogenesis, IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France
| | - Auguste Genovesio
- Scientific Center for Computational Biology, IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France
| | - Xavier Morin
- Cell Division and Neurogenesis, IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France.
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Barbosa DJ, Duro J, Prevo B, Cheerambathur DK, Carvalho AX, Gassmann R. Dynactin binding to tyrosinated microtubules promotes centrosome centration in C. elegans by enhancing dynein-mediated organelle transport. PLoS Genet 2017; 13:e1006941. [PMID: 28759579 PMCID: PMC5552355 DOI: 10.1371/journal.pgen.1006941] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 08/10/2017] [Accepted: 07/25/2017] [Indexed: 12/01/2022] Open
Abstract
The microtubule-based motor dynein generates pulling forces for centrosome centration and mitotic spindle positioning in animal cells. How the essential dynein activator dynactin regulates these functions of the motor is incompletely understood. Here, we dissect the role of dynactin's microtubule binding activity, located in the p150 CAP-Gly domain and an adjacent basic patch, in the C. elegans zygote. Analysis of p150 mutants engineered by genome editing suggests that microtubule tip tracking of dynein-dynactin is dispensable for targeting the motor to the cell cortex and for generating robust cortical pulling forces. Instead, mutations in p150's CAP-Gly domain inhibit cytoplasmic pulling forces responsible for centration of centrosomes and attached pronuclei. The centration defects are mimicked by mutations of α-tubulin's C-terminal tyrosine, and both p150 CAP-Gly and tubulin tyrosine mutants decrease the frequency of early endosome transport from the cell periphery towards centrosomes during centration. Our results suggest that p150 GAP-Gly domain binding to tyrosinated microtubules promotes initiation of dynein-mediated organelle transport in the dividing one-cell embryo, and that this function of p150 is critical for generating cytoplasmic pulling forces for centrosome centration.
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Affiliation(s)
- Daniel J. Barbosa
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde (I3S), Universidade do Porto, Porto, Portugal
| | - Joana Duro
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde (I3S), Universidade do Porto, Porto, Portugal
| | - Bram Prevo
- Ludwig Institute for Cancer Research/Dept of Cellular & Molecular Medicine UCSD, La Jolla, CA, United States of America
| | - Dhanya K. Cheerambathur
- Ludwig Institute for Cancer Research/Dept of Cellular & Molecular Medicine UCSD, La Jolla, CA, United States of America
| | - Ana X. Carvalho
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde (I3S), Universidade do Porto, Porto, Portugal
| | - Reto Gassmann
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde (I3S), Universidade do Porto, Porto, Portugal
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28
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Estrem C, Fees CP, Moore JK. Dynein is regulated by the stability of its microtubule track. J Cell Biol 2017; 216:2047-2058. [PMID: 28572117 PMCID: PMC5496616 DOI: 10.1083/jcb.201611105] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 03/24/2017] [Accepted: 05/04/2017] [Indexed: 12/23/2022] Open
Abstract
How dynein motors accurately move cargoes is an important question. In budding yeast, dynein moves the mitotic spindle to the predetermined site of cytokinesis by pulling on astral microtubules. In this study, using high-resolution imaging in living cells, we discover that spindle movement is regulated by changes in microtubule plus-end dynamics that occur when dynein generates force. Mutants that increase plus-end stability increase the frequency and duration of spindle movements, causing positioning errors. We find that dynein plays a primary role in regulating microtubule dynamics by destabilizing microtubules. In contrast, the dynactin complex counteracts dynein and stabilizes microtubules through a mechanism involving the shoulder subcomplex and the cytoskeletal-associated protein glycine-rich domain of Nip100/p150glued Our results support a model in which dynein destabilizes its microtubule substrate by using its motility to deplete dynactin from the plus end. We propose that interplay among dynein, dynactin, and the stability of the microtubule substrate creates a mechanism that regulates accurate spindle positioning.
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Affiliation(s)
- Cassi Estrem
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO
| | - Colby P Fees
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO
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29
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Abstract
Asymmetric cell division during embryogenesis contributes to cell diversity by generating daughter cells that adopt distinct developmental fates. In this chapter, we summarize current knowledge of three examples of asymmetric cell division occurring in ascidian early embryos: (1) Three successive cell divisions that are asymmetric in terms of cell fate and unequal in cell size in the germline lineage at the embryo posterior pole. A subcellular structure, the centrosome-attracting body (CAB), and maternal PEM mRNAs localized within it control both the positioning of the cell division planes and segregation of the germ cell fates. (2) Asymmetric cell divisions involving endoderm and mesoderm germ layer separation. Asymmetric partitioning of zygotically expressed mRNA for Not, a homeodomain transcription factor, promotes the mesoderm fate and suppresses the endoderm fate. This asymmetric partitioning is mediated by transient nuclear migration toward the mesodermal pole of the mother cell, where the mRNA is delivered. In this case, there is no special regulation of cleavage plane orientation. (3) Asymmetric cell divisions in the marginal region of the vegetal hemisphere. The directed extracellular FGF and ephrin signals polarize the mother cells, inducing distinct fates in a pair of daughter cells (nerve versus notochord and mesenchyme versus muscle). The directions of cell division are regulated and oriented but independently of FGF and ephrin signaling. In these examples, polarization of the mother cells is facilitated by localized maternal factors, by delivery of transcripts from the nucleus to one pole of each cell, and by directed extracellular signals. Two cellular processes-asymmetric fate allocation and orientation of the cell division plane-are coupled by a single factor in the first example, but these processes are regulated independently in the third example. Thus, various modes of asymmetric cell division operate even at the early developmental stages in this single type of organism.
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Affiliation(s)
- Takefumi Negishi
- Division of Morphogenesis, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi, 444-8585, Japan
| | - Hiroki Nishida
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-Cho, Toyonaka, Osaka, 560-0043, Japan.
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30
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Tadenev ALD, Tarchini B. The Spindle Orientation Machinery Beyond Mitosis: When Cell Specialization Demands Polarization. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1002:209-225. [DOI: 10.1007/978-3-319-57127-0_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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31
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Pacquelet A. Asymmetric Cell Division in the One-Cell C. elegans Embryo: Multiple Steps to Generate Cell Size Asymmetry. Results Probl Cell Differ 2017; 61:115-140. [PMID: 28409302 DOI: 10.1007/978-3-319-53150-2_5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The first division of the one-cell C. elegans embryo has been a fundamental model in deciphering the mechanisms underlying asymmetric cell division. Polarization of the one-cell zygote is induced by a signal from the sperm centrosome and results in the asymmetric distribution of PAR proteins. Multiple mechanisms then maintain PAR polarity until the end of the first division. Once asymmetrically localized, PAR proteins control several essential aspects of asymmetric division, including the position of the mitotic spindle along the polarity axis. Coordination of the spindle and cytokinetic furrow positions is the next essential step to ensure proper asymmetric division. In this chapter, I review the different mechanisms underlying these successive steps of asymmetric division. Work from the last 30 years has revealed the existence of multiple and redundant regulatory pathways which ensure division robustness. Besides the essential role of PAR proteins, this work also emphasizes the importance of both microtubules and actomyosin throughout the different steps of asymmetric division.
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Affiliation(s)
- Anne Pacquelet
- CNRS, UMR6290, Rennes, France. .,Université de Rennes 1, Institut de Génétique et Développement de Rennes, Rennes, France. .,CNRS UMR6290-IGDR, 2 avenue du Professeur Léon Bernard, 35043, Rennes Cedex, France.
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32
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Pécréaux J, Redemann S, Alayan Z, Mercat B, Pastezeur S, Garzon-Coral C, Hyman AA, Howard J. The Mitotic Spindle in the One-Cell C. elegans Embryo Is Positioned with High Precision and Stability. Biophys J 2016; 111:1773-1784. [PMID: 27760363 PMCID: PMC5071606 DOI: 10.1016/j.bpj.2016.09.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 09/05/2016] [Accepted: 09/07/2016] [Indexed: 01/20/2023] Open
Abstract
Precise positioning of the mitotic spindle is important for specifying the plane of cell division, which in turn determines how the cytoplasmic contents of the mother cell are partitioned into the daughter cells, and how the daughters are positioned within the tissue. During metaphase in the early Caenorhabditis elegans embryo, the spindle is aligned and centered on the anterior-posterior axis by a microtubule-dependent machinery that exerts restoring forces when the spindle is displaced from the center. To investigate the accuracy and stability of centering, we tracked the position and orientation of the mitotic spindle during the first cell division with high temporal and spatial resolution. We found that the precision is remarkably high: the cell-to-cell variation in the transverse position of the center of the spindle during metaphase, as measured by the standard deviation, was only 1.5% of the length of the short axis of the cell. Spindle position is also very stable: the standard deviation of the fluctuations in transverse spindle position during metaphase was only 0.5% of the short axis of the cell. Assuming that stability is limited by fluctuations in the number of independent motor elements such as microtubules or dyneins underlying the centering machinery, we infer that the number is ∼1000, consistent with the several thousand of astral microtubules in these cells. Astral microtubules grow out from the two spindle poles, make contact with the cell cortex, and then shrink back shortly thereafter. The high stability of centering can be accounted for quantitatively if, while making contact with the cortex, the astral microtubules buckle as they exert compressive, pushing forces. We thus propose that the large number of microtubules in the asters provides a highly precise mechanism for positioning the spindle during metaphase while assembly is completed before the onset of anaphase.
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Affiliation(s)
- Jacques Pécréaux
- Institute of Genetics and Development of Rennes, Unité Mixte de Recherche 6290, Centre National de la Recherche Scientifique, CS 34317, Rennes, France; Institute of Genetics and Development of Rennes, University Rennes 1, Rennes, France; Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
| | - Stefanie Redemann
- Dresden University of Technology, Dresden, Germany; Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Zahraa Alayan
- Institute of Genetics and Development of Rennes, Unité Mixte de Recherche 6290, Centre National de la Recherche Scientifique, CS 34317, Rennes, France; Institute of Genetics and Development of Rennes, University Rennes 1, Rennes, France
| | - Benjamin Mercat
- Institute of Genetics and Development of Rennes, Unité Mixte de Recherche 6290, Centre National de la Recherche Scientifique, CS 34317, Rennes, France; Institute of Genetics and Development of Rennes, University Rennes 1, Rennes, France
| | - Sylvain Pastezeur
- Institute of Genetics and Development of Rennes, Unité Mixte de Recherche 6290, Centre National de la Recherche Scientifique, CS 34317, Rennes, France; Institute of Genetics and Development of Rennes, University Rennes 1, Rennes, France
| | - Carlos Garzon-Coral
- Shriram Center of Bioengineering and Chemical Engineering, Stanford University, Stanford, California; Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Anthony A Hyman
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Jonathon Howard
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany; Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, Connecticut.
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Portegijs V, Fielmich LE, Galli M, Schmidt R, Muñoz J, van Mourik T, Akhmanova A, Heck AJR, Boxem M, van den Heuvel S. Multisite Phosphorylation of NuMA-Related LIN-5 Controls Mitotic Spindle Positioning in C. elegans. PLoS Genet 2016; 12:e1006291. [PMID: 27711157 PMCID: PMC5053539 DOI: 10.1371/journal.pgen.1006291] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 08/10/2016] [Indexed: 11/18/2022] Open
Abstract
During cell division, the mitotic spindle segregates replicated chromosomes to opposite poles of the cell, while the position of the spindle determines the plane of cleavage. Spindle positioning and chromosome segregation depend on pulling forces on microtubules extending from the centrosomes to the cell cortex. Critical in pulling force generation is the cortical anchoring of cytoplasmic dynein by a conserved ternary complex of Gα, GPR-1/2, and LIN-5 proteins in C. elegans (Gα–LGN–NuMA in mammals). Previously, we showed that the polarity kinase PKC-3 phosphorylates LIN-5 to control spindle positioning in early C. elegans embryos. Here, we investigate whether additional LIN-5 phosphorylations regulate cortical pulling forces, making use of targeted alteration of in vivo phosphorylated residues by CRISPR/Cas9-mediated genetic engineering. Four distinct in vivo phosphorylated LIN-5 residues were found to have critical functions in spindle positioning. Two of these residues form part of a 30 amino acid binding site for GPR-1, which we identified by reverse two-hybrid screening. We provide evidence for a dual-kinase mechanism, involving GSK3 phosphorylation of S659 followed by phosphorylation of S662 by casein kinase 1. These LIN-5 phosphorylations promote LIN-5–GPR-1/2 interaction and contribute to cortical pulling forces. The other two critical residues, T168 and T181, form part of a cyclin-dependent kinase consensus site and are phosphorylated by CDK1-cyclin B in vitro. We applied a novel strategy to characterize early embryonic defects in lethal T168,T181 knockin substitution mutants, and provide evidence for sequential LIN-5 N-terminal phosphorylation and dephosphorylation in dynein recruitment. Our data support that phosphorylation of multiple LIN-5 domains by different kinases contributes to a mechanism for spatiotemporal control of spindle positioning and chromosome segregation. Protein kinases control biological processes by phosphorylating specific amino acids of substrate proteins. It remains a major challenge to identify which phosphorylation events are critical in vivo and how phosphorylation affects protein function. Recent developments in CRISPR/Cas9-based genetic engineering make it possible to substitute individual amino acids, which allows investigating the role of single and multi-site phosphorylation of substrates in vivo. Here, we focus on an intensively phosphorylated cell division protein, LIN-5NuMA. C. elegans LIN-5 participates in chromosome segregation and is essential for positioning the spindle and cell cleavage plane during asymmetric cell division. Previously, we demonstrated that the polarity kinase PKC-3 phosphorylates LIN-5 to inhibit its function. Our current analysis reveals four additional phosphorylated residues that are critical for LIN-5 function. Two of these residues contribute to the interaction of LIN-5 with its binding partner GPR-1/2, whereas the other two residues are critical in dynein motor recruitment by LIN-5. Together, our results reveal that multisite phosphorylation of LIN-5 is essential to ensure proper chromosome segregation and spindle positioning.
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Affiliation(s)
- Vincent Portegijs
- Developmental Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Lars-Eric Fielmich
- Developmental Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Matilde Galli
- Developmental Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Ruben Schmidt
- Developmental Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Javier Muñoz
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Tim van Mourik
- Developmental Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Anna Akhmanova
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Albert J. R. Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Mike Boxem
- Developmental Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Sander van den Heuvel
- Developmental Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
- * E-mail:
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Mitotic Spindle Positioning in the EMS Cell of Caenorhabditis elegans Requires LET-99 and LIN-5/NuMA. Genetics 2016; 204:1177-1189. [PMID: 27672093 DOI: 10.1534/genetics.116.192831] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 09/16/2016] [Indexed: 12/24/2022] Open
Abstract
Asymmetric divisions produce daughter cells with different fates, and thus are critical for animal development. During asymmetric divisions, the mitotic spindle must be positioned on a polarized axis to ensure the differential segregation of cell fate determinants into the daughter cells. In many cell types, a cortically localized complex consisting of Gα, GPR-1/2, and LIN-5 (Gαi/Pins/Mud, Gαi/LGN/NuMA) mediates the recruitment of dynactin/dynein, which exerts pulling forces on astral microtubules to physically position the spindle. The conserved PAR polarity proteins are known to regulate both cytoplasmic asymmetry and spindle positioning in many cases. However, spindle positioning also occurs in response to cell signaling cues that appear to be PAR-independent. In the four-cell Caenorhabditis elegans embryo, Wnt and Mes-1/Src-1 signaling pathways act partially redundantly to align the spindle on the anterior/posterior axis of the endomesodermal (EMS) precursor cell. It is unclear how those extrinsic signals individually contribute to spindle positioning and whether either pathway acts via conserved spindle positioning regulators. Here, we genetically test the involvement of Gα, LIN-5, and their negative regulator LET-99, in transducing EMS spindle positioning polarity cues. We also examined whether the C. elegans ortholog of another spindle positioning regulator, DLG-1, is required. We show that LET-99 acts in the Mes-1/Src-1 pathway for spindle positioning. LIN-5 is also required for EMS spindle positioning, possibly through a Gα- and DLG-1-independent mechanism.
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Syrovatkina V, Alegre KO, Dey R, Huang XY. Regulation, Signaling, and Physiological Functions of G-Proteins. J Mol Biol 2016; 428:3850-68. [PMID: 27515397 DOI: 10.1016/j.jmb.2016.08.002] [Citation(s) in RCA: 265] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 07/31/2016] [Accepted: 08/03/2016] [Indexed: 12/31/2022]
Abstract
Heterotrimeric guanine-nucleotide-binding regulatory proteins (G-proteins) mainly relay the information from G-protein-coupled receptors (GPCRs) on the plasma membrane to the inside of cells to regulate various biochemical functions. Depending on the targeted cell types, tissues, and organs, these signals modulate diverse physiological functions. The basic schemes of heterotrimeric G-proteins have been outlined. In this review, we briefly summarize what is known about the regulation, signaling, and physiological functions of G-proteins. We then focus on a few less explored areas such as the regulation of G-proteins by non-GPCRs and the physiological functions of G-proteins that cannot be easily explained by the known G-protein signaling pathways. There are new signaling pathways and physiological functions for G-proteins to be discovered and further interrogated. With the advancements in structural and computational biological techniques, we are closer to having a better understanding of how G-proteins are regulated and of the specificity of G-protein interactions with their regulators.
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Affiliation(s)
- Viktoriya Syrovatkina
- Department of Physiology and Biophysics, Weill Cornell Medical College, of Cornell University, 1300 York Avenue, New York, NY 10065, USA
| | - Kamela O Alegre
- Department of Physiology and Biophysics, Weill Cornell Medical College, of Cornell University, 1300 York Avenue, New York, NY 10065, USA
| | - Raja Dey
- Department of Physiology and Biophysics, Weill Cornell Medical College, of Cornell University, 1300 York Avenue, New York, NY 10065, USA
| | - Xin-Yun Huang
- Department of Physiology and Biophysics, Weill Cornell Medical College, of Cornell University, 1300 York Avenue, New York, NY 10065, USA.
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36
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Besseling J, Bringmann H. Engineered non-Mendelian inheritance of entire parental genomes in C. elegans. Nat Biotechnol 2016; 34:982-6. [PMID: 27479498 DOI: 10.1038/nbt.3643] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 07/05/2016] [Indexed: 11/09/2022]
Abstract
The ability to rewrite the rules of genetic segregation would open new possibilities in diverse areas of biotechnology ranging from breeding to epigenetics. Here we engineer non-Mendelian inheritance of the entire maternal or paternal genome in Caenorhabditis elegans by changing the structure of the mitotic spindle during the first cell division of the zygote. Using germline-specific overexpression of a single protein, the conserved microtubule force regulator GPR-1, we increase forces that pull on spindle poles to convert the single bipolar mitotic spindle to two monopolar spindles. This generates two-cell embryos in which one cell contains only the maternal chromosomes and the other cell contains only the paternal chromosomes. As the embryo develops, each cell of the animal, including the germ cells, contains the genetic material of only one parent, resulting in hybrid F1 animals. Progeny of these animals (F2) inherit either only F0 maternal or only F0 paternal chromosomes, and thus descend from only either of their grandparents' gametes.
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Affiliation(s)
- Judith Besseling
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Henrik Bringmann
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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37
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di Pietro F, Echard A, Morin X. Regulation of mitotic spindle orientation: an integrated view. EMBO Rep 2016; 17:1106-30. [PMID: 27432284 DOI: 10.15252/embr.201642292] [Citation(s) in RCA: 212] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 06/17/2016] [Indexed: 12/18/2022] Open
Abstract
Mitotic spindle orientation is essential for cell fate decisions, epithelial maintenance, and tissue morphogenesis. In most animal cell types, the dynein motor complex is anchored at the cell cortex and exerts pulling forces on astral microtubules to position the spindle. Early studies identified the evolutionarily conserved Gαi/LGN/NuMA complex as a key regulator that polarizes cortical force generators. In recent years, a combination of genetics, biochemistry, modeling, and live imaging has contributed to decipher the mechanisms of spindle orientation. Here, we highlight the dynamic nature of the assembly of this complex and discuss the molecular regulation of its localization. Remarkably, a number of LGN-independent mechanisms were described recently, whereas NuMA remains central in most pathways involved in recruiting force generators at the cell cortex. We also describe the emerging role of the actin cortex in spindle orientation and discuss how dynamic astral microtubule formation is involved. We further give an overview on instructive external signals that control spindle orientation in tissues. Finally, we discuss the influence of cell geometry and mechanical forces on spindle orientation.
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Affiliation(s)
- Florencia di Pietro
- Cell Division and Neurogenesis Laboratory, Ecole Normale Supérieure CNRS Inserm Institut de Biologie de l'Ecole Normale Supérieure (IBENS) PSL Research University, Paris, France Institute of Doctoral Studies (IFD), Sorbonne Universités Université Pierre et Marie Curie-Université Paris 6, Paris, France
| | - Arnaud Echard
- Membrane Traffic and Cell Division Laboratory, Cell Biology and Infection Department, Institut Pasteur, Paris, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 3691, Paris, France
| | - Xavier Morin
- Cell Division and Neurogenesis Laboratory, Ecole Normale Supérieure CNRS Inserm Institut de Biologie de l'Ecole Normale Supérieure (IBENS) PSL Research University, Paris, France
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38
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Kotak S, Afshar K, Busso C, Gönczy P. Aurora A kinase regulates proper spindle positioning in C. elegans and in human cells. J Cell Sci 2016; 129:3015-25. [PMID: 27335426 DOI: 10.1242/jcs.184416] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 06/16/2016] [Indexed: 01/04/2023] Open
Abstract
Accurate spindle positioning is essential for error-free cell division. The one-cell Caenorhabditis elegans embryo has proven instrumental for dissecting mechanisms governing spindle positioning. Despite important progress, how the cortical forces that act on astral microtubules to properly position the spindle are modulated is incompletely understood. Here, we report that the PP6 phosphatase PPH-6 and its associated subunit SAPS-1, which positively regulate pulling forces acting on spindle poles, associate with the Aurora A kinase AIR-1 in C. elegans embryos. We show that acute inactivation of AIR-1 during mitosis results in excess pulling forces on astral microtubules. Furthermore, we uncover that AIR-1 acts downstream of PPH-6-SAPS-1 in modulating spindle positioning, and that PPH-6-SAPS-1 negatively regulates AIR-1 localization at the cell cortex. Moreover, we show that Aurora A and the PP6 phosphatase subunit PPP6C are also necessary for spindle positioning in human cells. There, Aurora A is needed for the cortical localization of NuMA and dynein during mitosis. Overall, our work demonstrates that Aurora A kinases and PP6 phosphatases have an ancient function in modulating spindle positioning, thus contributing to faithful cell division.
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Affiliation(s)
- Sachin Kotak
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne CH-1015, Switzerland
| | - Katayon Afshar
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne CH-1015, Switzerland
| | - Coralie Busso
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne CH-1015, Switzerland
| | - Pierre Gönczy
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne CH-1015, Switzerland
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39
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Tame MA, Raaijmakers JA, Afanasyev P, Medema RH. Chromosome misalignments induce spindle-positioning defects. EMBO Rep 2016; 17:317-25. [PMID: 26882550 PMCID: PMC4772978 DOI: 10.15252/embr.201541143] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 12/08/2015] [Accepted: 01/04/2016] [Indexed: 11/09/2022] Open
Abstract
Cortical pulling forces on astral microtubules are essential to position the spindle. These forces are generated by cortical dynein, a minus-end directed motor. Previously, another dynein regulator termed Spindly was proposed to regulate dynein-dependent spindle positioning. However, the mechanism of how Spindly regulates spindle positioning has remained elusive. Here, we find that the misalignment of chromosomes caused by Spindly depletion is directly provoking spindle misorientation. Chromosome misalignments induced by CLIP-170 or CENP-E depletion or by noscapine treatment are similarly accompanied by severe spindle-positioning defects. We find that cortical LGN is actively displaced from the cortex when misaligned chromosomes are in close proximity. Preventing the KT recruitment of Plk1 by the depletion of PBIP1 rescues cortical LGN enrichment near misaligned chromosomes and re-establishes proper spindle orientation. Hence, KT-enriched Plk1 is responsible for the negative regulation of cortical LGN localization. In summary, we uncovered a compelling molecular link between chromosome alignment and spindle orientation defects, both of which are implicated in tumorigenesis.
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Affiliation(s)
- Mihoko A Tame
- Department of Cell Biology and Cancer Genomics Center, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Jonne A Raaijmakers
- Department of Cell Biology and Cancer Genomics Center, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Pavel Afanasyev
- The Maastricht Multimodal Molecular Imaging Institute, Maastricht University, Maastricht, The Netherlands
| | - René H Medema
- Department of Cell Biology and Cancer Genomics Center, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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40
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Chiu CW, Monat C, Robitaille M, Lacomme M, Daulat AM, Macleod G, McNeill H, Cayouette M, Angers S. SAPCD2 Controls Spindle Orientation and Asymmetric Divisions by Negatively Regulating the Gαi-LGN-NuMA Ternary Complex. Dev Cell 2016; 36:50-62. [DOI: 10.1016/j.devcel.2015.12.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 11/15/2015] [Accepted: 12/11/2015] [Indexed: 01/01/2023]
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41
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Bezanilla M, Gladfelter AS, Kovar DR, Lee WL. Cytoskeletal dynamics: a view from the membrane. ACTA ACUST UNITED AC 2015; 209:329-37. [PMID: 25963816 PMCID: PMC4427793 DOI: 10.1083/jcb.201502062] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Many aspects of cytoskeletal assembly and dynamics can be recapitulated in vitro; yet, how the cytoskeleton integrates signals in vivo across cellular membranes is far less understood. Recent work has demonstrated that the membrane alone, or through membrane-associated proteins, can effect dynamic changes to the cytoskeleton, thereby impacting cell physiology. Having identified mechanistic links between membranes and the actin, microtubule, and septin cytoskeletons, these studies highlight the membrane’s central role in coordinating these cytoskeletal systems to carry out essential processes, such as endocytosis, spindle positioning, and cellular compartmentalization.
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Affiliation(s)
- Magdalena Bezanilla
- Department of Biology, University of Massachusetts Amherst, Amherst, MA 01003
| | - Amy S Gladfelter
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755
| | - David R Kovar
- Department of Molecular Genetics and Cell Biology and Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637 Department of Molecular Genetics and Cell Biology and Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637
| | - Wei-Lih Lee
- Department of Biology, University of Massachusetts Amherst, Amherst, MA 01003
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42
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Kiyomitsu T. Mechanisms of daughter cell-size control during cell division. Trends Cell Biol 2015; 25:286-95. [DOI: 10.1016/j.tcb.2014.12.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 11/14/2014] [Accepted: 12/02/2014] [Indexed: 10/24/2022]
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Spiró Z, Thyagarajan K, De Simone A, Träger S, Afshar K, Gönczy P. Clathrin regulates centrosome positioning by promoting acto-myosin cortical tension in C. elegans embryos. Development 2014; 141:2712-23. [PMID: 24961801 DOI: 10.1242/dev.107508] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Regulation of centrosome and spindle positioning is crucial for spatial cell division control. The one-cell Caenorhabditis elegans embryo has proven attractive for dissecting the mechanisms underlying centrosome and spindle positioning in a metazoan organism. Previous work revealed that these processes rely on an evolutionarily conserved force generator complex located at the cell cortex. This complex anchors the motor protein dynein, thus allowing cortical pulling forces to be exerted on astral microtubules emanating from microtubule organizing centers (MTOCs). Here, we report that the clathrin heavy chain CHC-1 negatively regulates pulling forces acting on centrosomes during interphase and on spindle poles during mitosis in one-cell C. elegans embryos. We establish a similar role for the cytokinesis/apoptosis/RNA-binding protein CAR-1 and uncover that CAR-1 is needed to maintain proper levels of CHC-1. We demonstrate that CHC-1 is necessary for normal organization of the cortical acto-myosin network and for full cortical tension. Furthermore, we establish that the centrosome positioning phenotype of embryos depleted of CHC-1 is alleviated by stabilizing the acto-myosin network. Conversely, we demonstrate that slight perturbations of the acto-myosin network in otherwise wild-type embryos results in excess centrosome movements resembling those in chc-1(RNAi) embryos. We developed a 2D computational model to simulate cortical rigidity-dependent pulling forces, which recapitulates the experimental data and further demonstrates that excess centrosome movements are produced at medium cortical rigidity values. Overall, our findings lead us to propose that clathrin plays a critical role in centrosome positioning by promoting acto-myosin cortical tension.
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Affiliation(s)
- Zoltán Spiró
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne CH-1015, Switzerland
| | - Kalyani Thyagarajan
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne CH-1015, Switzerland
| | - Alessandro De Simone
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne CH-1015, Switzerland
| | - Sylvain Träger
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne CH-1015, Switzerland
| | - Katayoun Afshar
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne CH-1015, Switzerland
| | - Pierre Gönczy
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne CH-1015, Switzerland
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44
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Raaijmakers JA, Medema RH. Function and regulation of dynein in mitotic chromosome segregation. Chromosoma 2014; 123:407-22. [PMID: 24871939 DOI: 10.1007/s00412-014-0468-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 05/08/2014] [Accepted: 05/09/2014] [Indexed: 12/23/2022]
Abstract
Cytoplasmic dynein is a large minus-end-directed microtubule motor complex, involved in many different cellular processes including intracellular trafficking, organelle positioning, and microtubule organization. Furthermore, dynein plays essential roles during cell division where it is implicated in multiple processes including centrosome separation, chromosome movements, spindle organization, spindle positioning, and mitotic checkpoint silencing. How is a single motor able to fulfill this large array of functions and how are these activities temporally and spatially regulated? The answer lies in the unique composition of the dynein motor and in the interactions it makes with multiple regulatory proteins that define the time and place where dynein becomes active. Here, we will focus on the different mitotic processes that dynein is involved in, and how its regulatory proteins act to support dynein. Although dynein is highly conserved amongst eukaryotes (with the exception of plants), there is significant variability in the cellular processes that depend on dynein in different species. In this review, we concentrate on the functions of cytoplasmic dynein in mammals but will also refer to data obtained in other model organisms that have contributed to our understanding of dynein function in higher eukaryotes.
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Affiliation(s)
- J A Raaijmakers
- Department of Cell Biology and Cancer Genomics Center, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, Netherlands
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45
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46
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Tame MA, Raaijmakers JA, van den Broek B, Lindqvist A, Jalink K, Medema RH. Astral microtubules control redistribution of dynein at the cell cortex to facilitate spindle positioning. Cell Cycle 2014; 13:1162-70. [PMID: 24553118 PMCID: PMC4013166 DOI: 10.4161/cc.28031] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Cytoplasmic dynein is recruited to the cell cortex in early mitosis, where it can generate pulling forces on astral microtubules to position the mitotic spindle. Recent work has shown that dynein displays a dynamic asymmetric cortical localization, and that dynein recruitment is negatively regulated by spindle pole-proximity. This results in oscillating dynein recruitment to opposite sides of the cortex to center the mitotic spindle. However, although the centrosome-derived signal that promotes displacement of dynein has been identified, it is currently unknown how dynein is re-recruited to the cortex once it has been displaced. Here we show that re-recruitment of cortical dynein requires astral microtubules. We find that microtubules are necessary for the sustained localized enrichment of dynein at the cortex. Furthermore, we show that stabilization of astral microtubules causes spindle misorientation, followed by mispositioning of dynein at the cortex. Thus, our results demonstrate the importance of astral microtubules in the dynamic regulation of cortical dynein recruitment in mitosis.
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Affiliation(s)
- Mihoko A Tame
- Division of Cell Biology; The Netherlands Cancer Institute; Amsterdam, The Netherlands
| | - Jonne A Raaijmakers
- Division of Cell Biology; The Netherlands Cancer Institute; Amsterdam, The Netherlands
| | - Bram van den Broek
- Division of Cell Biology; The Netherlands Cancer Institute; Amsterdam, The Netherlands
| | - Arne Lindqvist
- Department of Cell and Molecular Biology; Karolinska Institutet; Stockholm, Sweden
| | - Kees Jalink
- Division of Cell Biology; The Netherlands Cancer Institute; Amsterdam, The Netherlands
| | - René H Medema
- Division of Cell Biology; The Netherlands Cancer Institute; Amsterdam, The Netherlands
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47
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Almonacid M, Terret MÉ, Verlhac MH. Actin-based spindle positioning: new insights from female gametes. J Cell Sci 2014; 127:477-83. [PMID: 24413163 DOI: 10.1242/jcs.142711] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Asymmetric divisions are essential in metazoan development, where they promote the emergence of cell lineages. The mitotic spindle has astral microtubules that contact the cortex, which act as a sensor of cell geometry and as an integrator to orient cell division. Recent advances in live imaging revealed novel pools and roles of F-actin in somatic cells and in oocytes. In somatic cells, cytoplasmic F-actin is involved in spindle architecture and positioning. In starfish and mouse oocytes, newly discovered meshes of F-actin control chromosome gathering and spindle positioning. Because oocytes lack centrosomes and astral microtubules, F-actin networks are key players in the positioning of spindles by transmitting forces over long distances. Oocytes also achieve highly asymmetric divisions, and thus are excellent models to study the roles of these newly discovered F-actin networks in spindle positioning. Moreover, recent studies in mammalian oocytes provide a further understanding of the organisation of F-actin networks and their biophysical properties. In this Commentary, we present examples of the role of F-actin in spindle positioning and asymmetric divisions, with an emphasis on the most up-to-date studies from mammalian oocytes. We also address specific technical issues in the field, namely live imaging of F-actin networks and stress the need for interdisciplinary approaches.
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Affiliation(s)
- Maria Almonacid
- CIRB, Collège de France, CNRS-UMR7241, INSERM-U1050, 75231 Paris, Cedex 05, France
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48
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The novel zinc finger protein dASCIZ regulates mitosis in Drosophila via an essential role in dynein light-chain expression. Genetics 2013; 196:443-53. [PMID: 24336747 DOI: 10.1534/genetics.113.159541] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The essential zinc finger protein ASCIZ (also known as ATMIN, ZNF822) plays critical roles during lung organogenesis and B cell development in mice, where it regulates the expression of dynein light chain (DYNLL1/LC8), but its functions in other species including invertebrates are largely unknown. Here we report the identification of the Drosophila ortholog of ASCIZ (dASCIZ) and show that loss of dASCIZ function leads to pronounced mitotic delays with centrosome and spindle positioning defects during development, reminiscent of impaired dynein motor functions. Interestingly, similar mitotic and developmental defects were observed upon knockdown of the DYNLL/LC8-type dynein light chain Cutup (Ctp), and dASCIZ loss-of-function phenotypes could be suppressed by ectopic Ctp expression. Consistent with a genetic function of dASCIZ upstream of Ctp, we show that loss of dASCIZ led to reduced endogenous Ctp mRNA and protein levels and dramatically reduced Ctp-LacZ reporter gene activity in vivo, indicating that dASCIZ regulates development and mitosis as a Ctp transcription factor. We speculate that the more severe mitotic defects in the absence of ASCIZ in flies compared to mice may be due to redundancy with a second, ASCIZ-independent, Dynll2 gene in mammals in contrast to a single Ctp gene in Drosophila. Altogether, our data demonstrate that ASCIZ is an evolutionary highly conserved transcriptional regulator of dynein light-chain levels and a novel regulator of mitosis in flies.
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49
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Kotak S, Gönczy P. Mechanisms of spindle positioning: cortical force generators in the limelight. Curr Opin Cell Biol 2013; 25:741-8. [PMID: 23958212 DOI: 10.1016/j.ceb.2013.07.008] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 07/09/2013] [Accepted: 07/15/2013] [Indexed: 01/04/2023]
Abstract
Correct positioning of the spindle governs placement of the cytokinesis furrow and thus plays a crucial role in the partitioning of fate determinants and the disposition of daughter cells in a tissue. Converging evidence indicates that spindle positioning is often dictated by interactions between the plus-end of astral microtubules that emanate from the spindle poles and an evolutionary conserved cortical machinery that serves to pull on them. At the heart of this machinery lies a ternary complex (LIN-5/GPR-1/2/Gα in Caenorhabditis elegans and NuMA/LGN/Gαi in Homo sapiens) that promotes the presence of the motor protein dynein at the cell cortex. In this review, we discuss how the above components contribute to spindle positioning and how the underlying mechanisms are precisely regulated to ensure the proper execution of this crucial process in metazoan organisms.
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Affiliation(s)
- Sachin Kotak
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne CH-1005, Switzerland
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50
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Kotak S, Busso C, Gönczy P. NuMA phosphorylation by CDK1 couples mitotic progression with cortical dynein function. EMBO J 2013; 32:2517-29. [PMID: 23921553 DOI: 10.1038/emboj.2013.172] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 07/15/2013] [Indexed: 12/19/2022] Open
Abstract
Spindle positioning and spindle elongation are critical for proper cell division. In human cells, an evolutionary conserved ternary complex (NuMA/LGN/Gαi) anchors dynein at the cortex during metaphase, thus ensuring correct spindle positioning. Whether this complex contributes to anaphase spindle elongation is not known. More generally, the mechanisms coupling mitotic progression with spindle behaviour remain elusive. Here, we uncover that levels of cortical dynein markedly increase during anaphase in a NuMA-dependent manner. We demonstrate that during metaphase, CDK1-mediated phosphorylation at T2055 negatively regulates NuMA cortical localization and that this phosphorylation is counteracted by PPP2CA phosphatase activity. We establish that this tug of war is essential for proper levels of cortical dynein and thus spindle positioning during metaphase. Moreover, we find that upon CDK1 inactivation in anaphase, the rise in dephosphorylated NuMA at the cell cortex leads to cortical dynein enrichment, and thus to robust spindle elongation. Our findings uncover a mechanism whereby the status of NuMA phosphorylation coordinates mitotic progression with proper spindle function.
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Affiliation(s)
- Sachin Kotak
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
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