1
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Wong HN, Chen T, Wang PJ, Holzman LB. ARF6, a component of intercellular bridges, is essential for spermatogenesis in mice. Dev Biol 2024; 508:46-63. [PMID: 38242343 DOI: 10.1016/j.ydbio.2024.01.007] [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: 07/21/2023] [Revised: 01/05/2024] [Accepted: 01/16/2024] [Indexed: 01/21/2024]
Abstract
Male germ cells are connected by intercellular bridges (ICBs) in a syncytium due to incomplete cytokinesis. Syncytium is thought to be important for synchronized germ cell development by interchange of cytoplasmic factors via ICBs. Mammalian ADP-ribosylation factor 6 (ARF6) is a small GTPase that is involved in many cellular mechanisms including but not limited to regulating cellular structure, motility, vesicle trafficking and cytokinesis. ARF6 localizes to ICBs in spermatogonia and spermatocytes in mice. Here we report that mice with global depletion of ARF6 in adulthood using Ubc-CreERT2 display no observable phenotypes but are male sterile. ARF6-deficient males display a progressive loss of germ cells, including LIN28A-expressing spermatogonia, and ultimately develop Sertoli-cell-only syndrome. Specifically, intercellular bridges are lost in ARF6-deficient testis. Furthermore, germ cell-specific inactivation using the Ddx4-CreERT2 results in the same testicular morphological phenotype, showing the germ cell-intrinsic requirement of ARF6. Therefore, ARF6 is essential for spermatogenesis in mice and this function is conserved from Drosophila to mammals.
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Affiliation(s)
- Hetty N Wong
- Renal, Electrolyte, and Hypertension Division, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Tingfang Chen
- Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - P Jeremy Wang
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA, 19104, USA
| | - Lawrence B Holzman
- Renal, Electrolyte, and Hypertension Division, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, 19104, USA.
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2
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Sokac AM, Biel N, De Renzis S. Membrane-actin interactions in morphogenesis: Lessons learned from Drosophila cellularization. Semin Cell Dev Biol 2023; 133:107-122. [PMID: 35396167 PMCID: PMC9532467 DOI: 10.1016/j.semcdb.2022.03.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 03/18/2022] [Accepted: 03/21/2022] [Indexed: 01/12/2023]
Abstract
During morphogenesis, changes in the shapes of individual cells are harnessed to mold an entire tissue. These changes in cell shapes require the coupled remodeling of the plasma membrane and underlying actin cytoskeleton. In this review, we highlight cellularization of the Drosophila embryo as a model system to uncover principles of how membrane and actin dynamics are co-regulated in space and time to drive morphogenesis.
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Affiliation(s)
- Anna Marie Sokac
- Department of Cell and Developmental Biology, University of Illinois at Urbana Champaign, Urbana, IL 61801, USA; Graduate Program in Integrative and Molecular Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Natalie Biel
- Department of Cell and Developmental Biology, University of Illinois at Urbana Champaign, Urbana, IL 61801, USA; Graduate Program in Integrative and Molecular Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA
| | - Stefano De Renzis
- European Molecular Biology Laboratory Heidelberg, 69117 Heidelberg, Germany
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3
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Lipid Polarization during Cytokinesis. Cells 2022; 11:cells11243977. [PMID: 36552741 PMCID: PMC9776629 DOI: 10.3390/cells11243977] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 12/01/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022] Open
Abstract
The plasma membrane of eukaryotic cells is composed of a large number of lipid species that are laterally segregated into functional domains as well as asymmetrically distributed between the outer and inner leaflets. Additionally, the spatial distribution and organization of these lipids dramatically change in response to various cellular states, such as cell division, differentiation, and apoptosis. Division of one cell into two daughter cells is one of the most fundamental requirements for the sustenance of growth in all living organisms. The successful completion of cytokinesis, the final stage of cell division, is critically dependent on the spatial distribution and organization of specific lipids. In this review, we discuss the properties of various lipid species associated with cytokinesis and the mechanisms involved in their polarization, including forward trafficking, endocytic recycling, local synthesis, and cortical flow models. The differences in lipid species requirements and distribution in mitotic vs. male meiotic cells will be discussed. We will concentrate on sphingolipids and phosphatidylinositols because their transbilayer organization and movement may be linked via the cytoskeleton and thus critically regulate various steps of cytokinesis.
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4
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Sechi S, Karimpour-Ghahnavieh A, Frappaolo A, Di Francesco L, Piergentili R, Schininà E, D’Avino PP, Giansanti MG. Identification of GOLPH3 Partners in Drosophila Unveils Potential Novel Roles in Tumorigenesis and Neural Disorders. Cells 2021; 10:cells10092336. [PMID: 34571985 PMCID: PMC8468827 DOI: 10.3390/cells10092336] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/01/2021] [Accepted: 09/03/2021] [Indexed: 12/28/2022] Open
Abstract
Golgi phosphoprotein 3 (GOLPH3) is a highly conserved peripheral membrane protein localized to the Golgi apparatus and the cytosol. GOLPH3 binding to Golgi membranes depends on phosphatidylinositol 4-phosphate [PI(4)P] and regulates Golgi architecture and vesicle trafficking. GOLPH3 overexpression has been correlated with poor prognosis in several cancers, but the molecular mechanisms that link GOLPH3 to malignant transformation are poorly understood. We recently showed that PI(4)P-GOLPH3 couples membrane trafficking with contractile ring assembly during cytokinesis in dividing Drosophila spermatocytes. Here, we use affinity purification coupled with mass spectrometry (AP-MS) to identify the protein-protein interaction network (interactome) of Drosophila GOLPH3 in testes. Analysis of the GOLPH3 interactome revealed enrichment for proteins involved in vesicle-mediated trafficking, cell proliferation and cytoskeleton dynamics. In particular, we found that dGOLPH3 interacts with the Drosophila orthologs of Fragile X mental retardation protein and Ataxin-2, suggesting a potential role in the pathophysiology of disorders of the nervous system. Our findings suggest novel molecular targets associated with GOLPH3 that might be relevant for therapeutic intervention in cancers and other human diseases.
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Affiliation(s)
- Stefano Sechi
- Istituto di Biologia e Patologia Molecolari del CNR, c/o Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (S.S.); (A.K.-G.); (A.F.); (R.P.)
| | - Angela Karimpour-Ghahnavieh
- Istituto di Biologia e Patologia Molecolari del CNR, c/o Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (S.S.); (A.K.-G.); (A.F.); (R.P.)
| | - Anna Frappaolo
- Istituto di Biologia e Patologia Molecolari del CNR, c/o Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (S.S.); (A.K.-G.); (A.F.); (R.P.)
| | - Laura Di Francesco
- Dipartimento di Scienze Biochimiche A. Rossi Fanelli, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (L.D.F.); (E.S.)
| | - Roberto Piergentili
- Istituto di Biologia e Patologia Molecolari del CNR, c/o Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (S.S.); (A.K.-G.); (A.F.); (R.P.)
| | - Eugenia Schininà
- Dipartimento di Scienze Biochimiche A. Rossi Fanelli, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (L.D.F.); (E.S.)
| | - Pier Paolo D’Avino
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK;
| | - Maria Grazia Giansanti
- Istituto di Biologia e Patologia Molecolari del CNR, c/o Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (S.S.); (A.K.-G.); (A.F.); (R.P.)
- Correspondence: ; Tel.: +39-064-991-2555
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5
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Carim SC, Kechad A, Hickson GRX. Animal Cell Cytokinesis: The Rho-Dependent Actomyosin-Anilloseptin Contractile Ring as a Membrane Microdomain Gathering, Compressing, and Sorting Machine. Front Cell Dev Biol 2020; 8:575226. [PMID: 33117802 PMCID: PMC7575755 DOI: 10.3389/fcell.2020.575226] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 09/07/2020] [Indexed: 12/19/2022] Open
Abstract
Cytokinesis is the last step of cell division that partitions the cellular organelles and cytoplasm of one cell into two. In animal cells, cytokinesis requires Rho-GTPase-dependent assembly of F-actin and myosin II (actomyosin) to form an equatorial contractile ring (CR) that bisects the cell. Despite 50 years of research, the precise mechanisms of CR assembly, tension generation and closure remain elusive. This hypothesis article considers a holistic view of the CR that, in addition to actomyosin, includes another Rho-dependent cytoskeletal sub-network containing the scaffold protein, Anillin, and septin filaments (collectively termed anillo-septin). We synthesize evidence from our prior work in Drosophila S2 cells that actomyosin and anillo-septin form separable networks that are independently anchored to the plasma membrane. This latter realization leads to a simple conceptual model in which CR assembly and closure depend upon the micro-management of the membrane microdomains to which actomyosin and anillo-septin sub-networks are attached. During CR assembly, actomyosin contractility gathers and compresses its underlying membrane microdomain attachment sites. These microdomains resist this compression, which builds tension. During CR closure, membrane microdomains are transferred from the actomyosin sub-network to the anillo-septin sub-network, with which they flow out of the CR as it advances. This relative outflow of membrane microdomains regulates tension, reduces the circumference of the CR and promotes actomyosin disassembly all at the same time. According to this hypothesis, the metazoan CR can be viewed as a membrane microdomain gathering, compressing and sorting machine that intrinsically buffers its own tension through coordination of actomyosin contractility and anillo-septin-membrane relative outflow, all controlled by Rho. Central to this model is the abandonment of the dogmatic view that the plasma membrane is always readily deformable by the underlying cytoskeleton. Rather, the membrane resists compression to build tension. The notion that the CR might generate tension through resistance to compression of its own membrane microdomain attachment sites, can account for numerous otherwise puzzling observations and warrants further investigation using multiple systems and methods.
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Affiliation(s)
- Sabrya C. Carim
- CHU Sainte-Justine Research Center, Université de Montréal, Montréal, QC, Canada
| | - Amel Kechad
- CHU Sainte-Justine Research Center, Université de Montréal, Montréal, QC, Canada
| | - Gilles R. X. Hickson
- CHU Sainte-Justine Research Center, Université de Montréal, Montréal, QC, Canada
- Département de Pathologie et Biologie Cellulaire, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
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6
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Ramos M, Cortés JCG, Sato M, Rincón SA, Moreno MB, Clemente-Ramos JÁ, Osumi M, Pérez P, Ribas JC. Two S. pombe septation phases differ in ingression rate, septum structure, and response to F-actin loss. J Cell Biol 2019; 218:4171-4194. [PMID: 31597680 PMCID: PMC6891078 DOI: 10.1083/jcb.201808163] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 04/19/2019] [Accepted: 09/10/2019] [Indexed: 12/28/2022] Open
Abstract
Ramos et al. establish that fission yeast septation proceeds in two phases. Initially, the septum is immature and, upon F-actin depolymerization, loses the Bgs1 glucan synthase and fails to ingress. During a second phase, the mature septum can maintain Bgs1 and ingression without F-actin, and ingression becomes Cdc42 and exocyst dependent. In fission yeast, cytokinesis requires a contractile actomyosin ring (CR) coupled to membrane and septum ingression. Septation proceeds in two phases. In anaphase B, the septum ingresses slowly. During telophase, the ingression rate increases, and the CR becomes dispensable. Here, we explore the relationship between the CR and septation by analyzing septum ultrastructure, ingression, and septation proteins in cells lacking F-actin. We show that the two phases of septation correlate with septum maturation and the response of cells to F-actin removal. During the first phase, the septum is immature and, following F-actin removal, rapidly loses the Bgs1 glucan synthase from the membrane edge and fails to ingress. During the second phase, the rapidly ingressing mature septum can maintain a Bgs1 ring and septum ingression without F-actin, but ingression becomes Cdc42 and exocyst dependent. Our results provide new insights into fungal cytokinesis and reveal the dual function of CR as an essential landmark for the concentration of Bgs1 and a contractile structure that maintains septum shape and synthesis.
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Affiliation(s)
- Mariona Ramos
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
| | - Juan Carlos G Cortés
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
| | - Mamiko Sato
- Laboratory of Electron Microscopy/Bio-imaging Center, Japan Women's University, Bunkyo-ku, Tokyo, Japan
| | - Sergio A Rincón
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
| | - M Belén Moreno
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
| | - José Ángel Clemente-Ramos
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
| | - Masako Osumi
- Laboratory of Electron Microscopy/Bio-imaging Center, Japan Women's University, Bunkyo-ku, Tokyo, Japan.,Integrated Imaging Research Support, Chiyoda-ku, Tokyo, Japan
| | - Pilar Pérez
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
| | - Juan Carlos Ribas
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca, Spain
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7
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Kumar D, Golchoubian B, Belevich I, Jokitalo E, Schlaitz AL. REEP3 and REEP4 determine the tubular morphology of the endoplasmic reticulum during mitosis. Mol Biol Cell 2019; 30:1377-1389. [PMID: 30995177 PMCID: PMC6724692 DOI: 10.1091/mbc.e18-11-0698] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The endoplasmic reticulum (ER) is extensively remodeled during metazoan open mitosis. However, whether the ER becomes more tubular or more cisternal during mitosis is controversial, and dedicated factors governing the morphology of the mitotic ER have remained elusive. Here, we describe the ER membrane proteins REEP3 and REEP4 as major determinants of ER morphology in metaphase cells. REEP3/4 are specifically required for generating the high-curvature morphology of mitotic ER and promote ER tubulation through their reticulon homology domains (RHDs). This ER-shaping activity of REEP3/4 is distinct from their previously described function to clear ER from metaphase chromatin. We further show that related REEP proteins do not contribute to mitotic ER shaping and provide evidence that the REEP3/4 carboxyterminus mediates regulation of the proteins. These findings confirm that ER converts to higher curvature during mitosis, identify REEP3/4 as specific and crucial morphogenic factors mediating ER tubulation during mitosis, and define the first cell cycle-specific role for RHD proteins.
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Affiliation(s)
- Darshan Kumar
- Cell and Molecular Biology Program, University of Helsinki, FI-00014 Helsinki, Finland
| | - Banafsheh Golchoubian
- Center for Molecular Biology of Heidelberg University (ZMBH), D-69120 Heidelberg, Germany
| | - Ilya Belevich
- Cell and Molecular Biology Program, University of Helsinki, FI-00014 Helsinki, Finland.,Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, FI-00014 Helsinki, Finland
| | - Eija Jokitalo
- Cell and Molecular Biology Program, University of Helsinki, FI-00014 Helsinki, Finland.,Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, FI-00014 Helsinki, Finland
| | - Anne-Lore Schlaitz
- Center for Molecular Biology of Heidelberg University (ZMBH), D-69120 Heidelberg, Germany
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8
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Onwubiko UN, Mlynarczyk PJ, Wei B, Habiyaremye J, Clack A, Abel SM, Das ME. A Cdc42 GEF, Gef1, through endocytosis organizes F-BAR Cdc15 along the actomyosin ring and promotes concentric furrowing. J Cell Sci 2019; 132:jcs223776. [PMID: 30709916 PMCID: PMC6432710 DOI: 10.1242/jcs.223776] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 01/21/2019] [Indexed: 01/17/2023] Open
Abstract
During cytokinesis, fission yeast coordinates actomyosin ring constriction with septum ingression, resulting in concentric furrow formation by a poorly defined mechanism. We report that Schizosaccharomyces pombe cells lacking the Cdc42 activator Gef1, combined with an activated allele of the formin, Cdc12, display non-concentric furrowing. Non-concentrically furrowing cells display uneven distribution of the scaffold Cdc15 along the ring. This suggests that, after ring assembly, uniform Cdc15 distribution along the ring enables proper furrow formation. We find that, after assembly, Cdc15 is recruited to the ring in an Arp2/3 complex-dependent manner and is decreased in the activated cdc12 mutant. Cdc15 at cortical endocytic patches shows increased levels and extended lifetimes in gef1 and activated cdc12 mutants. We hypothesize endocytosis helps recruit Cdc15 to assembled rings; uneven Cdc15 distribution at the ring occurs when endocytic patches contain increased Cdc15 levels and the patch-association rate is slow. Based on this, we developed a mathematical model that captures experimentally observed Cdc15 distributions along the ring. We propose that, at the ring, Gef1 and endocytic events promote uniform Cdc15 organization to enable proper septum ingression and concentric furrow formation.
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Affiliation(s)
- Udo N Onwubiko
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Paul J Mlynarczyk
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Bin Wei
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Julius Habiyaremye
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Amanda Clack
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Steven M Abel
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Maitreyi E Das
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
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9
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Molecular mechanisms of contractile-ring constriction and membrane trafficking in cytokinesis. Biophys Rev 2018; 10:1649-1666. [PMID: 30448943 DOI: 10.1007/s12551-018-0479-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 11/06/2018] [Indexed: 12/14/2022] Open
Abstract
In this review, we discuss the molecular mechanisms of cytokinesis from plants to humans, with a focus on contribution of membrane trafficking to cytokinesis. Selection of the division site in fungi, metazoans, and plants is reviewed, as well as the assembly and constriction of a contractile ring in fungi and metazoans. We also provide an introduction to exocytosis and endocytosis, and discuss how they contribute to successful cytokinesis in eukaryotic cells. The conservation in the coordination of membrane deposition and cytoskeleton during cytokinesis in fungi, metazoans, and plants is highlighted.
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10
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11
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Frappaolo A, Sechi S, Belloni G, Piergentili R, Giansanti MG. Visualization of cleavage furrow proteins in fixed dividing spermatocytes. Methods Cell Biol 2017; 137:85-103. [PMID: 28065322 DOI: 10.1016/bs.mcb.2016.03.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cytokinesis separates the cytoplasmic organelles and the duplicated genome into two daughter cells at the end of cell division. In animal cell cytokinesis, assembly and constriction of the contractile apparatus must be finely coordinated with plasma membrane remodeling and vesicle trafficking at the cleavage furrow. Accurate control of these events during cell cleavage is a fundamental task in all organisms and is also essential for maintaining ploidy and preventing neoplastic transformation. Drosophila male meiosis provides a well-suited cell system for exploring the molecular mechanisms underlying cytokinesis, combining the powerful tools of Drosophila genetics with unique cytological characteristics. Remarkably the large size of male meiotic cells highly facilitates cytological analysis of cytokinesis. Here we describe the main procedures that we use for fixing and visualizing cleavage furrow proteins in male meiotic cells. Moreover, we detail our protocol to detect protein interactions in fixed dividing spermatocytes by applying in situ proximity ligation assay.
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Affiliation(s)
- A Frappaolo
- Istituto di Biologia e Patologia Molecolari del CNR, Università di Roma Sapienza, Roma, Italy
| | - S Sechi
- Istituto di Biologia e Patologia Molecolari del CNR, Università di Roma Sapienza, Roma, Italy
| | - G Belloni
- Istituto di Biologia e Patologia Molecolari del CNR, Università di Roma Sapienza, Roma, Italy
| | - R Piergentili
- Istituto di Biologia e Patologia Molecolari del CNR, Università di Roma Sapienza, Roma, Italy
| | - M G Giansanti
- Istituto di Biologia e Patologia Molecolari del CNR, Università di Roma Sapienza, Roma, Italy
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12
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Abstract
Cytokinesis is a complex cellular process that leads to a physical separation of two daughter cells. The key to a successful cytokinesis is a coordinated reorganization of cellular cytoskeleton and membrane trafficking pathways. Consequently, Rab GTPases recently emerged as major regulators of cellular division. Rabs belong to a superfamily of small monomeric GTPases that regulate a diverse array of cellular functions. Rabs in particular are well-established regulators of membrane transport and have been shown to mediate several membrane transport steps including vesicle formation, molecular motor-dependent vesicle transport and targeting of transport vesicles and organelles to their correct destinations. Significantly, several Rab GTPases also have been shown to function in regulating cell division. In this review, we discuss latest findings about the function of Rabs and polarized membrane transport during different steps of cytokinesis as well as during the final stage of cell division known as abscission.
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Affiliation(s)
- Paulius Gibieža
- a Institute of Cardiology, Lithuanian University of Health Sciences , Kaunas , Lithuania
| | - Rytis Prekeris
- b Department of Cell and Developmental Biology , University of Colorado Anschutz Medical Campus , Aurora , CO , USA
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13
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Wang N, Lee IJ, Rask G, Wu JQ. Roles of the TRAPP-II Complex and the Exocyst in Membrane Deposition during Fission Yeast Cytokinesis. PLoS Biol 2016; 14:e1002437. [PMID: 27082518 PMCID: PMC4833314 DOI: 10.1371/journal.pbio.1002437] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 03/15/2016] [Indexed: 12/27/2022] Open
Abstract
The cleavage-furrow tip adjacent to the actomyosin contractile ring is believed to be the predominant site for plasma-membrane insertion through exocyst-tethered vesicles during cytokinesis. Here we found that most secretory vesicles are delivered by myosin-V on linear actin cables in fission yeast cytokinesis. Surprisingly, by tracking individual exocytic and endocytic events, we found that vesicles with new membrane are deposited to the cleavage furrow relatively evenly during contractile-ring constriction, but the rim of the cleavage furrow is the main site for endocytosis. Fusion of vesicles with the plasma membrane requires vesicle tethers. Our data suggest that the transport particle protein II (TRAPP-II) complex and Rab11 GTPase Ypt3 help to tether secretory vesicles or tubulovesicular structures along the cleavage furrow while the exocyst tethers vesicles at the rim of the division plane. We conclude that the exocyst and TRAPP-II complex have distinct localizations at the division site, but both are important for membrane expansion and exocytosis during cytokinesis. Two putative vesicle tethers—the exocyst and TRAPP-II complexes—localize differently at the division plane to ensure efficient plasma-membrane deposition along the whole cleavage furrow during cytokinesis in the fission yeast Schizosaccharomyces pombe. Cytokinesis partitions a mother cell into two daughter cells at the end of each cell-division cycle. A significant amount of new plasma membrane is needed at the cleavage furrow during cytokinesis in many cell types. Membrane expansion is achieved through the balance of exocytosis and endocytosis. It is poorly understood where and when the membrane is deposited and retrieved during cytokinesis. By tracking individual vesicles with high spatiotemporal resolution and using electron microscopy, we found that new membrane is deposited relatively evenly along the cleavage furrow in fission yeast, while the rim of the division plane is the predominant site for endocytosis. The secretory vesicles/compartments carrying new membrane are mainly delivered along formin-nucleated actin cables by myosin-V motors. Surprisingly, we find that both exocytosis and endocytosis at the division site are ramped up before contractile-ring constriction and last until daughter-cell separation. We discovered that two putative vesicle tethers, the exocyst and TRAPP-II complexes, localize to different sites at the cleavage furrow to promote tethering of different, yet overlapping, classes of secretory vesicles/compartments for exocytosis and new membrane deposition.
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Affiliation(s)
- Ning Wang
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
| | - I-Ju Lee
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
| | - Galen Rask
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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14
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Mavor LM, Miao H, Zuo Z, Holly RM, Xie Y, Loerke D, Blankenship JT. Rab8 directs furrow ingression and membrane addition during epithelial formation in Drosophila melanogaster. Development 2016; 143:892-903. [PMID: 26839362 PMCID: PMC4813336 DOI: 10.1242/dev.128876] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 01/25/2016] [Indexed: 01/31/2023]
Abstract
One of the most fundamental changes in cell morphology is the ingression of a plasma membrane furrow. The Drosophila embryo undergoes several cycles of rapid furrow ingression during early development that culminate in the formation of an epithelial sheet. Previous studies have demonstrated the requirement for intracellular trafficking pathways in furrow ingression; however, the pathways that link compartmental behaviors with cortical furrow ingression events are unclear. Here, we show that Rab8 has striking dynamic behaviors in vivo. As furrows ingress, cytoplasmic Rab8 puncta are depleted and Rab8 accumulates at the plasma membrane in a location that coincides with known regions of directed membrane addition. We additionally use CRISPR/Cas9 technology to N-terminally tag Rab8, which is then used to address endogenous localization and function. Endogenous Rab8 displays partial coincidence with Rab11 and the Golgi, and this colocalization is enriched during the fast phase of cellularization. When Rab8 function is disrupted, furrow formation in the early embryo is completely abolished. We also demonstrate that Rab8 behaviors require the function of the exocyst complex subunit Sec5 as well as the recycling endosome protein Rab11. Active, GTP-locked Rab8 is primarily associated with dynamic membrane compartments and the plasma membrane, whereas GDP-locked Rab8 forms large cytoplasmic aggregates. These studies suggest a model in which active Rab8 populations direct furrow ingression by guiding the targeted delivery of cytoplasmic membrane stores to the cell surface through interactions with the exocyst tethering complex.
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Affiliation(s)
- Lauren M Mavor
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Hui Miao
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Zhongyuan Zuo
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Ryan M Holly
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Yi Xie
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Dinah Loerke
- Department of Physics, University of Denver, Denver, CO 80208, USA
| | - J Todd Blankenship
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
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15
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Ratiometric Fluorescence Live Imaging Analysis of Membrane Lipid Order in Arabidopsis Mitotic Cells Using a Lipid Order-Sensitive Probe. Methods Mol Biol 2016; 1370:227-39. [PMID: 26659966 DOI: 10.1007/978-1-4939-3142-2_17] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Eukaryotic cells contain membranes exhibiting different levels of lipid order mostly related to their relative amount of sterol-rich domains, thought to mediate temporal and spatial organization of cellular processes. We previously provided evidence in Arabidopsis thaliana that sterols are crucial for execution of cytokinesis, the last stage of cell division. Recently, we used di-4-ANEPPDHQ, a fluorescent probe sensitive to order of lipid phases, to quantify the level of membrane order of the cell plate, the membrane structure separating daughter cells during somatic cytokinesis of higher plant cells. By employing quantitative, ratiometric fluorescence microscopy for mapping localized lipid order levels, we revealed that the Arabidopsis cell plate represents a high-lipid-order domain of the plasma membrane. Here, we describe step-by-step protocols and troubleshooting for ratiometric live imaging procedures employing the di-4-ANEPPDHQ fluorescent probe for quantification of membrane lipid order during plant cell division in suspension cell cultures and roots of Arabidopsis thaliana.
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16
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Hsu JF, Hsieh PY, Hsu HY, Shigeto S. When cells divide: Label-free multimodal spectral imaging for exploratory molecular investigation of living cells during cytokinesis. Sci Rep 2015; 5:17541. [PMID: 26632877 PMCID: PMC4668386 DOI: 10.1038/srep17541] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 11/02/2015] [Indexed: 12/23/2022] Open
Abstract
In vivo, molecular-level investigation of cytokinesis, the climax of the cell cycle, not only deepens our understanding of how life continues, but it will also open up new possibilities of diagnosis/prognosis of cancer cells. Although fluorescence-based methods have been widely employed to address this challenge, they require a fluorophore to be designed for a specific known biomolecule and introduced into the cell. Here, we present a label-free spectral imaging approach based on multivariate curve resolution analysis of Raman hyperspectral data that enables exploratory untargeted studies of mammalian cell cytokinesis. We derived intrinsic vibrational spectra and intracellular distributions of major biomolecular components (lipids and proteins) in dividing and nondividing human colon cancer cells. In addition, we discovered an unusual autofluorescent lipid component that appears predominantly in the vicinity of the cleavage furrow during cytokinesis. This autofluorescence signal could be utilized as an endogenous probe for monitoring and visualizing cytokinesis in vivo.
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Affiliation(s)
- Jen-Fang Hsu
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan
| | - Pei-Ying Hsieh
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan
| | - Hsin-Yun Hsu
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan
| | - Shinsuke Shigeto
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan
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17
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Giansanti MG, Vanderleest TE, Jewett CE, Sechi S, Frappaolo A, Fabian L, Robinett CC, Brill JA, Loerke D, Fuller MT, Blankenship JT. Exocyst-Dependent Membrane Addition Is Required for Anaphase Cell Elongation and Cytokinesis in Drosophila. PLoS Genet 2015; 11:e1005632. [PMID: 26528720 PMCID: PMC4631508 DOI: 10.1371/journal.pgen.1005632] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 10/07/2015] [Indexed: 11/18/2022] Open
Abstract
Mitotic and cytokinetic processes harness cell machinery to drive chromosomal segregation and the physical separation of dividing cells. Here, we investigate the functional requirements for exocyst complex function during cell division in vivo, and demonstrate a common mechanism that directs anaphase cell elongation and cleavage furrow progression during cell division. We show that onion rings (onr) and funnel cakes (fun) encode the Drosophila homologs of the Exo84 and Sec8 exocyst subunits, respectively. In onr and fun mutant cells, contractile ring proteins are recruited to the equatorial region of dividing spermatocytes. However, cytokinesis is disrupted early in furrow ingression, leading to cytokinesis failure. We use high temporal and spatial resolution confocal imaging with automated computational analysis to quantitatively compare wild-type versus onr and fun mutant cells. These results demonstrate that anaphase cell elongation is grossly disrupted in cells that are compromised in exocyst complex function. Additionally, we observe that the increase in cell surface area in wild type peaks a few minutes into cytokinesis, and that onr and fun mutant cells have a greatly reduced rate of surface area growth specifically during cell division. Analysis by transmission electron microscopy reveals a massive build-up of cytoplasmic astral membrane and loss of normal Golgi architecture in onr and fun spermatocytes, suggesting that exocyst complex is required for proper vesicular trafficking through these compartments. Moreover, recruitment of the small GTPase Rab11 and the PITP Giotto to the cleavage site depends on wild-type function of the exocyst subunits Exo84 and Sec8. Finally, we show that the exocyst subunit Sec5 coimmunoprecipitates with Rab11. Our results are consistent with the exocyst complex mediating an essential, coordinated increase in cell surface area that potentiates anaphase cell elongation and cleavage furrow ingression. The cell shape changes that underlie cell division are some of the most fundamental changes in cell morphology. Here, we show that a common membrane trafficking pathway is required for both the cell lengthening that occurs during anaphase, and the physical separation of a cell into two equal daughter cells. We measure and define the periods of surface area increase during cell division in Drosophila male germline cells, and demonstrate that subunits of the exocyst tethering complex are required for this process. Invagination of the cleavage furrow fails at an early stage in exocyst mutant spermatocytes, suggesting that membrane addition is part of the initial ingression mechanism. In the absence of exocyst complex function, vesicular trafficking pathways are disrupted, leading to enlarged cytoplasmic membrane stores, and disruption of Golgi architecture. In addition, a vesicular Rab protein, Rab11, biochemically associates with the exocyst complex subunit Sec5. These results suggest that remodeling of the plasma membrane and targeted increases in surface area are an active part of the fundamental mechanisms that permit eukaryotic cell division to occur.
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Affiliation(s)
- Maria Grazia Giansanti
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Roma, Italy
- * E-mail: (MGG), (JTB)
| | | | - Cayla E. Jewett
- Department of Biological Sciences, University of Denver, Denver, Colorado, United States of America
| | - Stefano Sechi
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Roma, Italy
| | - Anna Frappaolo
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Roma, Italy
| | - Lacramioara Fabian
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Carmen C. Robinett
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America
| | - Julie A. Brill
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Dinah Loerke
- Department of Physics, University of Denver, Denver, Colorado, United States of America
| | - Margaret T. Fuller
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, California, United States of America
| | - J. Todd Blankenship
- Department of Biological Sciences, University of Denver, Denver, Colorado, United States of America
- * E-mail: (MGG), (JTB)
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18
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Nakamura Y, Asano A, Hosaka Y, Takeuchi T, Iwanaga T, Yamano Y. Expression and intracellular localization of TBC1D9, a Rab GTPase-accelerating protein, in mouse testes. Exp Anim 2015; 64:415-24. [PMID: 26119791 PMCID: PMC4637379 DOI: 10.1538/expanim.15-0016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Membrane trafficking in male germ cells contributes to their development via cell morphological changes and acrosome formation. TBC family proteins work as Rab GTPase accelerating proteins (GAPs), which negatively regulate Rab proteins, to mediate membrane trafficking. In this study, we analyzed the expression of a Rab GAP, TBC1D9, in mouse organs and the intracellular localization of the gene products. Tbc1d9 showed abundant expression in adult mice testis. We found that the Tbc1d9 mRNA was expressed in primary and secondary spermatocytes, and that the TBC1D9 protein was expressed in spermatocytes and round spermatids. In 293T cells, TBC1D9-GFP proteins were localized in the endosome and Golgi apparatus. Compartments that were positive for the constitutive active mutants of Rab7 and Rab9 were also positive for TBC1D9 isoform 1. In addition, TBC1D9 proteins were associated with Rab7 and Rab9, respectively. These results indicate that TBC1D9 is expressed mainly in spermatocytes, and suggest that TBC1D9 regulates membrane trafficking pathways related to Rab9- or Rab7-positive vesicles.
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Affiliation(s)
- Yutaka Nakamura
- Laboratory of Veterinary Biochemistry, Faculty of Agriculture, Tottori University, Japan
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19
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Holly RM, Mavor LM, Zuo Z, Blankenship JT. A rapid, membrane-dependent pathway directs furrow formation through RalA in the early Drosophila embryo. Development 2015; 142:2316-28. [PMID: 26092850 DOI: 10.1242/dev.120998] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 05/13/2015] [Indexed: 01/31/2023]
Abstract
Plasma membrane furrow formation is crucial in cell division and cytokinesis. Furrow formation in early syncytial Drosophila embryos is exceptionally rapid, with furrows forming in as little as 3.75 min. Here, we use 4D imaging to identify furrow formation, stabilization, and regression periods, and identify a rapid, membrane-dependent pathway that is essential for plasma membrane furrow formation in vivo. Myosin II function is thought to provide the ingression force for cytokinetic furrows, but the role of membrane trafficking pathways in guiding furrow formation is less clear. We demonstrate that a membrane trafficking pathway centered on Ras-like protein A (RalA) is required for fast furrow ingression in the early fly embryo. RalA function is absolutely required for furrow formation and initiation. In the absence of RalA and furrow function, chromosomal segregation is aberrant and polyploid nuclei are observed. RalA localizes to syncytial furrows, and mediates the movement of exocytic vesicles to the plasma membrane. Sec5, which is an exocyst complex subunit and localizes to ingressing furrows in wild-type embryos, becomes punctate and loses its cortical association in the absence of RalA function. Rab8 also fails to traffic to the plasma membrane and accumulates aberrantly in the cytoplasm in RalA disrupted embryos. RalA localization precedes F-actin recruitment to the furrow tip, suggesting that membrane trafficking might function upstream of cytoskeletal remodeling. These studies identify a pathway, which stretches from Rab8 to RalA and the exocyst complex, that mediates rapid furrow formation in early Drosophila embryos.
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Affiliation(s)
- Ryan M Holly
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Lauren M Mavor
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Zhongyuan Zuo
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - J Todd Blankenship
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
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20
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Abstract
Cell division ends with the physical separation of the two daughter cells, a process known as cytokinesis. This final event ensures that nuclear and cytoplasmic contents are accurately partitioned between the two nascent cells. Cytokinesis is one of the most dramatic changes in cell shape and requires an extensive reorganization of the cell's cytoskeleton. Here, we describe the cytoskeletal structures, factors, and signaling pathways that orchestrate this robust and yet highly dynamic process in animal cells. Finally, we discuss possible future directions in this growing area of cell division research and its implications in human diseases, including cancer.
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Affiliation(s)
- Pier Paolo D'Avino
- Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| | - Maria Grazia Giansanti
- Istituto di Biologia e Patologia Molecolari c/o Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, 00185 Roma, Italy
| | - Mark Petronczki
- Cell Division and Aneuploidy Laboratory, Cancer Research UK-London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, United Kingdom
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21
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Kita A, Higa M, Doi A, Satoh R, Sugiura R. Imp2, the PSTPIP homolog in fission yeast, affects sensitivity to the immunosuppressant FK506 and membrane trafficking in fission yeast. Biochem Biophys Res Commun 2015; 457:273-9. [PMID: 25580011 DOI: 10.1016/j.bbrc.2014.12.100] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Accepted: 12/22/2014] [Indexed: 11/18/2022]
Abstract
Cytokinesis is a highly ordered process that divides one cell into two cells, which is functionally linked to the dynamic remodeling of the plasma membrane coordinately with various events such as membrane trafficking. Calcineurin is a highly conserved serine/threonine protein phosphatase, which regulates multiple biological functions, such as membrane trafficking and cytokinesis. Here, we isolated imp2-c3, a mutant allele of the imp2(+) gene, encoding a homolog of the mouse PSTPIP1 (proline-serine-threonine phosphatase interacting protein 1), using a genetic screen for mutations that are synthetically lethal with calcineurin deletion in fission yeast. The imp2-c3 mutants showed a defect in cytokinesis with multi-septated phenotypes, which was further enhanced upon treatment with the calcineurin inhibitor FK506. Notably, electron micrographs revealed that the imp2-c3 mutant cells accumulated aberrant multi-lamella Golgi structures and putative post-Golgi secretory vesicles, and exhibited fragmented vacuoles in addition to thickened septa. Consistently, imp2-c3 mutants showed a reduced secretion of acid phosphatase and defects in vacuole fusion. The imp2-c3 mutant cells exhibited a weakened cell wall, similar to the membrane trafficking mutants identified in the same genetic screen such as ypt3-i5. These findings implicate the PSTPIP1 homolog Imp2 in Golgi/vacuole function, thereby affecting various cellular processes, including cytokinesis and cell integrity.
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Affiliation(s)
- Ayako Kita
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502, Japan
| | - Mari Higa
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502, Japan
| | - Akira Doi
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502, Japan; Japan Society for the Promotion of Science, 1-8 Chiyoda-ku, Tokyo 102-8472, Japan
| | - Ryosuke Satoh
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502, Japan
| | - Reiko Sugiura
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502, Japan.
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22
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Frescatada-Rosa M, Stanislas T, Backues SK, Reichardt I, Men S, Boutté Y, Jürgens G, Moritz T, Bednarek SY, Grebe M. High lipid order of Arabidopsis cell-plate membranes mediated by sterol and DYNAMIN-RELATED PROTEIN1A function. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 80:745-57. [PMID: 25234576 PMCID: PMC4280860 DOI: 10.1111/tpj.12674] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Revised: 08/21/2014] [Accepted: 09/04/2014] [Indexed: 05/22/2023]
Abstract
Membranes of eukaryotic cells contain high lipid-order sterol-rich domains that are thought to mediate temporal and spatial organization of cellular processes. Sterols are crucial for execution of cytokinesis, the last stage of cell division, in diverse eukaryotes. The cell plate of higher-plant cells is the membrane structure that separates daughter cells during somatic cytokinesis. Cell-plate formation in Arabidopsis relies on sterol- and DYNAMIN-RELATED PROTEIN1A (DRP1A)-dependent endocytosis. However, functional relationships between lipid membrane order or lipid packing and endocytic machinery components during eukaryotic cytokinesis have not been elucidated. Using ratiometric live imaging of lipid order-sensitive fluorescent probes, we show that the cell plate of Arabidopsis thaliana represents a dynamic, high lipid-order membrane domain. The cell-plate lipid order was found to be sensitive to pharmacological and genetic alterations of sterol composition. Sterols co-localize with DRP1A at the cell plate, and DRP1A accumulates in detergent-resistant membrane fractions. Modifications of sterol concentration or composition reduce cell-plate membrane order and affect DRP1A localization. Strikingly, DRP1A function itself is essential for high lipid order at the cell plate. Our findings provide evidence that the cell plate represents a high lipid-order domain, and pave the way to explore potential feedback between lipid order and function of dynamin-related proteins during cytokinesis.
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Affiliation(s)
- Márcia Frescatada-Rosa
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå UniversitySE-90187, Umeå, Sweden
| | - Thomas Stanislas
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå UniversitySE-90187, Umeå, Sweden
| | - Steven K Backues
- Department of Biochemistry, University of Wisconsin-MadisonMadison, WI, 53706, USA
- ‡Present address: 6036 Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI, 48109-2216, USA
| | - Ilka Reichardt
- Department of Developmental Genetics, Centre for Plant Molecular Biology, University of TübingenAuf der Morgenstelle 3, D-72076, Tübingen, Germany
- §Present address: Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr Bohr Gasse 3, A-1030, Vienna, Austria
| | - Shuzhen Men
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå UniversitySE-90187, Umeå, Sweden
- ¶Present address: College of Life Sciences, Nankai University, 94 Weijin Road, Nankai District, Tianjin, 300071, China
| | - Yohann Boutté
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå UniversitySE-90187, Umeå, Sweden
- **Present address: Membrane Biogenesis Laboratory, UMR 5200 CNRS, Université Bordeaux Segalen Bâtiment A3, INRA Bordeaux Aquitaine BP81, 71 Avenue Edouard Bourlaux, 33883, F-Villenave d'Ornon, France
| | - Gerd Jürgens
- Department of Developmental Genetics, Centre for Plant Molecular Biology, University of TübingenAuf der Morgenstelle 3, D-72076, Tübingen, Germany
| | - Thomas Moritz
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural SciencesSE-90183, Umeå, Sweden
| | - Sebastian Y Bednarek
- Department of Biochemistry, University of Wisconsin-MadisonMadison, WI, 53706, USA
| | - Markus Grebe
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå UniversitySE-90187, Umeå, Sweden
- Institute for Biochemistry and Biology, Plant Physiology, University of PotsdamKarl Liebknecht Straße 24-25, Building 20, D-14476, Potsdam-Golm, Germany
- *For correspondence (e-mail )
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23
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Phosphoinositides: Lipids with informative heads and mastermind functions in cell division. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1851:832-43. [PMID: 25449648 DOI: 10.1016/j.bbalip.2014.10.013] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 10/21/2014] [Accepted: 10/28/2014] [Indexed: 01/22/2023]
Abstract
Phosphoinositides are low abundant but essential phospholipids in eukaryotic cells and refer to phosphatidylinositol and its seven polyphospho-derivatives. In this review, we summarize our current knowledge on phosphoinositides in multiple aspects of cell division in animal cells, including mitotic cell rounding, longitudinal cell elongation, cytokinesis furrow ingression, intercellular bridge abscission and post-cytokinesis events. PtdIns(4,5)P₂production plays critical roles in spindle orientation, mitotic cell shape and bridge stability after furrow ingression by recruiting force generator complexes and numerous cytoskeleton binding proteins. Later, PtdIns(4,5)P₂hydrolysis and PtdIns3P production are essential for normal cytokinesis abscission. Finally, emerging functions of PtdIns3P and likely PtdIns(4,5)P₂have recently been reported for midbody remnant clearance after abscission. We describe how the multiple functions of phosphoinositides in cell division reflect their distinct roles in local recruitment of protein complexes, membrane traffic and cytoskeleton remodeling. This article is part of a Special Issue entitled Phosphoinositides.
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24
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Giansanti MG, Sechi S, Frappaolo A, Belloni G, Piergentili R. Cytokinesis in Drosophila male meiosis. SPERMATOGENESIS 2014; 2:185-196. [PMID: 23094234 PMCID: PMC3469441 DOI: 10.4161/spmg.21711] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cytokinesis separates the cytoplasm and the duplicated genome into two daughter cells at the end of cell division. This process must be finely regulated to maintain ploidy and prevent tumor formation. Drosophila male meiosis provides an excellent cell system for investigating cytokinesis. Mutants affecting this process can be easily identified and spermatocytes are large cells particularly suitable for cytological analysis of cytokinetic structures. Over the past decade, the powerful tools of Drosophila genetics and the unique characteristics of this cell system have led researchers to identify molecular players of the cell cleavage machinery and to address important open questions. Although spermatocyte cytokinesis is incomplete, resulting in formation of stable intercellular bridges, the molecular mechanisms are largely conserved in somatic cells. Thus, studies of Drosophila male meiosis will shed new light on the complex cell circuits regulating furrow ingression and substantially further our knowledge of cancer and other human diseases.
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Affiliation(s)
- Maria Grazia Giansanti
- Istituto di Biologia e Patologia Molecolari del CNR; Dipartimento di Biologia e Biotecnologie Università Sapienza di Roma; Rome, Italy
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25
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Abstract
Cytokinesis is the final process of cell division cycle that properly separates cytoplasmic components and duplicated nuclei into two daughter cells. Plant cytokinesis occurs in phragmoplast, the cytokinetic machinery composed mainly of microtubule (MT) arrays. Recent studies have revealed that a plant-specific mitogen-activated protein kinase (MAPK) cascade is involved in cytokinesis. The activity of this cascade is controlled by cytokinesis-specific kinesin called NACK in tobacco and Arabidopsis, which is required for the cell plate formation in the phragmoplast. Functions of NACK are strictly controlled by cyclin-dependent kinase/cyclin B complexes so as to be activated at the correct timing for cytokinesis. Thus, this pathway constitutes a part of the regulatory system controlling the cell cycle progression. Here, we review recent advancements for understanding how the activation of this pathway can be specified in the late stage of the M phase and how this MAPK cascade can control cytokinesis through MT turnover.
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26
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Salzmann V, Chen C, Chiang CYA, Tiyaboonchai A, Mayer M, Yamashita YM. Centrosome-dependent asymmetric inheritance of the midbody ring in Drosophila germline stem cell division. Mol Biol Cell 2013; 25:267-75. [PMID: 24227883 PMCID: PMC3890347 DOI: 10.1091/mbc.e13-09-0541] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The midbody ring (MR) is asymmetrically segregated during asymmetric divisions of germline stem cells (GSCs) in Drosophila. Male GSCs, which inherit the mother centrosome, exclude the MR, whereas female GSCs, which inherit the daughter centrosome, inherit the MR. Moreover, stem cell identity correlates with the mode of MR inheritance. Many stem cells, including Drosophila germline stem cells (GSCs), divide asymmetrically, producing one stem cell and one differentiating daughter. Cytokinesis is often asymmetric, in that only one daughter cell inherits the midbody ring (MR) upon completion of abscission even in apparently symmetrically dividing cells. However, whether the asymmetry in cytokinesis correlates with cell fate or has functional relevance has been poorly explored. Here we show that the MR is asymmetrically segregated during GSC divisions in a centrosome age–dependent manner: male GSCs, which inherit the mother centrosome, exclude the MR, whereas female GSCs, which we here show inherit the daughter centrosome, inherit the MR. We further show that stem cell identity correlates with the mode of MR inheritance. Together our data suggest that the MR does not inherently dictate stem cell identity, although its stereotypical inheritance is under the control of stemness and potentially provides a platform for asymmetric segregation of certain factors.
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Affiliation(s)
- Viktoria Salzmann
- Life Sciences Institute, Center for Stem Cell Biology, University of Michigan, Ann Arbor, MI 48109 Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109 Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109 Department of Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109
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27
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Neto H, Kaupisch A, Collins LL, Gould GW. Syntaxin 16 is a master recruitment factor for cytokinesis. Mol Biol Cell 2013; 24:3663-74. [PMID: 24109596 PMCID: PMC3842993 DOI: 10.1091/mbc.e13-06-0302] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Syntaxin 16 is a key regulator of cytokinesis, as it is required for the recruitment of both recycling endosome–associated Exocyst and ESCRT machinery during late telophase. Therefore these two distinct facets of cytokinesis are inextricably linked. Recently it was shown that both recycling endosome and endosomal sorting complex required for transport (ESCRT) components are required for cytokinesis, in which they are believed to act in a sequential manner to bring about secondary ingression and abscission, respectively. However, it is not clear how either of these complexes is targeted to the midbody and whether their delivery is coordinated. The trafficking of membrane vesicles between different intracellular organelles involves the formation of soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE) complexes. Although membrane traffic is known to play an important role in cytokinesis, the contribution and identity of intracellular SNAREs to cytokinesis remain unclear. Here we demonstrate that syntaxin 16 is a key regulator of cytokinesis, as it is required for recruitment of both recycling endosome–associated Exocyst and ESCRT machinery during late telophase, and therefore that these two distinct facets of cytokinesis are inextricably linked.
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Affiliation(s)
- Hélia Neto
- Henry Wellcome Laboratory of Cell Biology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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Expression of α-taxilin in the murine gastrointestinal tract: potential implication in cell proliferation. Histochem Cell Biol 2013; 141:165-80. [PMID: 24091795 DOI: 10.1007/s00418-013-1147-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2013] [Indexed: 12/19/2022]
Abstract
α-Taxilin, a binding partner of the syntaxin family, is a candidate tumor marker. To gain insight into the physiological role of α-taxilin in normal tissues, we examined α-taxilin expression by Western blot and performed immunochemical analysis in the murine gastrointestinal tract where cell renewal vigorously occurs. α-Taxilin was expressed in the majority of the gastrointestinal tract and was prominently expressed in epithelial cells positive for Ki-67, a marker of actively proliferating cells. In the small intestine, α-taxilin was expressed in transient-amplifying cells and crypt base columnar cells intercalated among Paneth cells. In the corpus and antrum of the stomach, α-taxilin was expressed in cells localized in the lower pit and at the gland, respectively, but not in parietal or zymogenic cells. During development of the small intestine, α-taxilin was expressed in Ki-67-positive regions. Inhibition of cell proliferation by suppression of the Notch cascade using a γ-secretase inhibitor led to a decrease in α-taxilin- and Ki-67-positive cells in the stomach. These results suggest that expression of α-taxilin is regulated in parallel with cell proliferation in the murine gastrointestinal tract.
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Capalbo L, Montembault E, Takeda T, Bassi ZI, Glover DM, D'Avino PP. The chromosomal passenger complex controls the function of endosomal sorting complex required for transport-III Snf7 proteins during cytokinesis. Open Biol 2013; 2:120070. [PMID: 22724069 PMCID: PMC3376741 DOI: 10.1098/rsob.120070] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 04/12/2012] [Indexed: 12/11/2022] Open
Abstract
Cytokinesis controls the proper segregation of nuclear and cytoplasmic materials at the end of cell division. The chromosomal passenger complex (CPC) has been proposed to monitor the final separation of the two daughter cells at the end of cytokinesis in order to prevent cell abscission in the presence of DNA at the cleavage site, but the precise molecular basis for this is unclear. Recent studies indicate that abscission could be mediated by the assembly of filaments comprising components of the endosomal sorting complex required for transport-III (ESCRT-III). Here, we show that the CPC subunit Borealin interacts directly with the Snf7 components of ESCRT-III in both Drosophila and human cells. Moreover, we find that the CPC's catalytic subunit, Aurora B kinase, phosphorylates one of the three human Snf7 paralogues-CHMP4C-in its C-terminal tail, a region known to regulate its ability to form polymers and associate with membranes. Phosphorylation at these sites appears essential for CHMP4C function because their mutation leads to cytokinesis defects. We propose that CPC controls abscission timing through inhibition of ESCRT-III Snf7 polymerization and membrane association using two concurrent mechanisms: interaction of its Borealin component with Snf7 proteins and phosphorylation of CHMP4C by Aurora B.
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Affiliation(s)
- Luisa Capalbo
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
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Pathak R, Dermardirossian C. GEF-H1: orchestrating the interplay between cytoskeleton and vesicle trafficking. Small GTPases 2013; 4:174-9. [PMID: 23648943 DOI: 10.4161/sgtp.24616] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Vesicle trafficking is crucial for delivery of membrane compartments as well as signaling molecules to specific sites on the plasma membrane for regulation of diverse processes such as cell division, migration, polarity establishment and secretion. Rho GTPases are well-studied signaling molecules that regulate actin cytoskeleton in response to variety of extracellular stimuli. Increasing amounts of evidence suggest that Rho proteins play a critical role in vesicle trafficking in both the exocytic and endocytic pathways; however, the molecular mechanism underlying the process remains largely unclear. We recently defined a mechanism of action for RhoA in membrane trafficking pathways through regulation of the octameric complex exocyst in a manuscript published in Developmental Cell. We have shown that microtubule-associated RhoA-activating factor GEF-H1 is involved in endocytic and excocytic vesicle trafficking. GEF-H1 activates RhoA in response to RalA GTPase, which in turn regulates the localization and the assembly of exocyst components and exocytosis. Our work defines a mechanism for RhoA activation in response to RalA signaling and during vesicle trafficking. These results provide a framework for understanding how RhoA/GEF-H1 regulates the coordination of actin and microtubule cytoskeleton modulation and vesicle trafficking during migration and cell division.
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Affiliation(s)
- Ritu Pathak
- Departments of Immunology and Microbial Science; The Scripps Research Institute; La Jolla, CA USA
| | - Celine Dermardirossian
- Departments of Immunology and Microbial Science; The Scripps Research Institute; La Jolla, CA USA
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31
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Abstract
Cells internalize extracellular solutes, ligands and proteins and lipids in the plasma membrane (PM) by endocytosis. The removal of membrane from the PM is counteracted by endosomal recycling pathways that return the endocytosed proteins and lipids back to the PM. Recycling to the PM can occur from early endosomes. However, many cells have a distinct subpopulation of endosomes that have a mildly acidic pH of 6.5 and are involved in the endosomal recycling. These endosomes are dubbed recycling endosomes (REs). In recent years, studies have begun to reveal that function of REs is not limited to the endosomal recycling. In this review, I summarize the nature of membrane trafficking pathways that pass through REs and the cell biological roles of these pathways.
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Affiliation(s)
- Tomohiko Taguchi
- Laboratory of Pathological Cell Biology, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan
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32
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Teh OK, Shimono Y, Shirakawa M, Fukao Y, Tamura K, Shimada T, Hara-Nishimura I. The AP-1 µ Adaptin is Required for KNOLLE Localization at the Cell Plate to Mediate Cytokinesis in Arabidopsis. ACTA ACUST UNITED AC 2013; 54:838-47. [DOI: 10.1093/pcp/pct048] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Jung JJ, Inamdar SM, Tiwari A, Ye D, Lin F, Choudhury A. Syntaxin 16 regulates lumen formation during epithelial morphogenesis. PLoS One 2013; 8:e61857. [PMID: 23626741 PMCID: PMC3633931 DOI: 10.1371/journal.pone.0061857] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 03/15/2013] [Indexed: 11/19/2022] Open
Abstract
The formation and maintenance of cell-cell junctions, both under physiological and pathological conditions, requires the targeting and trafficking of junctional proteins. Proteins of the syntaxin (Stx)-family localize to a variety of subcellular membranes and contribute to intracellular transport of cargo by regulating vesicle fusion events at these sites. Unlike plasma membrane localized Stxs, the roles of endosome- and Golgi-localized stx proteins in epithelial morphogenesis are less understood. Here we show that Stx16- an endosome- and Golgi-localized target-membrane soluble N-ethylmaleimide attachment protein receptor (t-SNARE) that plays a role in membrane trafficking between these compartments - is essential for lumen development. In cultured Madin Darby Canine Kidney (MDCK) cells, Stx16 was selectively upregulated as sparsely plated cells attained confluency. Stx16-depleted confluent monolayers consistently showed lower transepithelial resistance than control monolayers, and failed to maintain endogenous and ectopically expressed E-cadherin at the adherens junctions due to decreased recycling. We further found that whereas cysts formed by MDCK cells cultured in Matrigel have a single hollow lumen, those formed by stx16-depleted counterparts had multiple lumens, due to abnormal orientiation of the mitotic spindle. Finally, a similar role for stx16 function in vivo is indicated by our analysis of pronephric-duct development in zebrafish expressing the claudinB:lynGFP transgene; lack of stx16 function in this structure (in stx16-morphant embryos) led to the development of enlarged, torturous pronephric ducts with more than one lumen. Taken together, our in vitro and in vivo studies establish a role for Stx16 in maintaining the integrity of cell-cell junctions, and thereby in morphogenesis of the kidney epithelial lumen.
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Affiliation(s)
- Jae-Joon Jung
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, Iowa, United States of America
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34
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Yeong FM. Multi-step down-regulation of the secretory pathway in mitosis: a fresh perspective on protein trafficking. Bioessays 2013; 35:462-71. [PMID: 23494566 PMCID: PMC3654163 DOI: 10.1002/bies.201200144] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The secretory pathway delivers proteins synthesized at the rough endoplasmic reticulum (RER) to various subcellular locations via the Golgi apparatus. Currently, efforts are focused on understanding the molecular machineries driving individual processes at the RER and Golgi that package, modify and transport proteins. However, studies are routinely performed using non-dividing cells. This obscures the critical issue of how the secretory pathway is affected by cell division. Indeed, several studies have indicated that protein trafficking is down-regulated during mitosis. Moreover, the RER and Golgi apparatus exhibit gross reorganization in mitosis. Here I provide a relatively neglected perspective of how the mitotic cyclin-dependent kinase (CDK1) could regulate various stages of the secretory pathway. I highlight several aspects of the mitotic control of protein trafficking that remain unresolved and suggest that further studies on how the mitotic CDK1 influences the secretory pathway are necessary to obtain a deeper understanding of protein transport.
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Affiliation(s)
- Foong May Yeong
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
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35
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Chen JS, Broadus MR, McLean JR, Feoktistova A, Ren L, Gould KL. Comprehensive proteomics analysis reveals new substrates and regulators of the fission yeast clp1/cdc14 phosphatase. Mol Cell Proteomics 2013; 12:1074-86. [PMID: 23297348 DOI: 10.1074/mcp.m112.025924] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The conserved family of Cdc14 phosphatases targets cyclin-dependent kinase substrates in yeast, mediating late mitotic signaling events. To discover substrates and regulators of the Schizosaccharomyces pombe Cdc14 phosphatase Clp1, TAP-tagged Clp1, and a substrate trapping mutant (Clp1-C286S) were purified from asynchronous and mitotic (prometaphase and anaphase) cells and binding partners were identified by 2D-LC-MS/MS. Over 100 Clp1-interacting proteins were consistently identified, over 70 of these were enriched in Clp1-C286S-TAP (potential substrates) and we and others detected Cdk1 phosphorylation sites in over half (44/73) of these potential substrates. According to GO annotations, Clp1-interacting proteins are involved in many essential cellular processes including mitosis, cytokinesis, ribosome biogenesis, transcription, and trafficking among others. We confirmed association and dephosphorylation of multiple candidate substrates, including a key scaffolding component of the septation initiation network called Cdc11, an essential kinase of the conserved morphogenesis-related NDR kinase network named Shk1, and multiple Mlu1-binding factor transcriptional regulators. In addition, we identified Sal3, a nuclear β-importin, as the sole karyopherin required for Clp1 nucleoplasmic shuttling, a key mode of Cdc14 phosphatase regulation. Finally, a handful of proteins were more abundant in wild type Clp1-TAP versus Clp1-C286S-TAP, suggesting that they may directly regulate Clp1 signaling or serve as scaffolding platforms to localize Clp1 activity.
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Affiliation(s)
- Jun-Song Chen
- Howard Hughes Medical Institute and Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, 1161 21 Avenue South, MCN B2309, Nashville, Tennessee 37232, USA
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36
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Chen CT, Ettinger AW, Huttner WB, Doxsey SJ. Resurrecting remnants: the lives of post-mitotic midbodies. Trends Cell Biol 2012; 23:118-28. [PMID: 23245592 DOI: 10.1016/j.tcb.2012.10.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Revised: 10/23/2012] [Accepted: 10/25/2012] [Indexed: 02/01/2023]
Abstract
Around a century ago, the midbody (MB) was described as a structural assembly within the intercellular bridge during cytokinesis that served to connect the two future daughter cells. The MB has become the focus of intense investigation through the identification of a growing number of diverse cellular and molecular pathways that localize to the MB and contribute to its cytokinetic functions, ranging from selective vesicle trafficking and regulated microtubule (MT), actin, and endosomal sorting complex required for transport (ESCRT) filament assembly and disassembly to post-translational modification, such as ubiquitination. More recent studies have revealed new and unexpected functions of MBs in post-mitotic cells. In this review, we provide a historical perspective, discuss exciting new roles for MBs beyond their cytokinetic function, and speculate on their potential contributions to pluripotency.
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Affiliation(s)
- Chun-Ting Chen
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
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37
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Pathak R, Delorme-Walker VD, Howell MC, Anselmo AN, White MA, Bokoch GM, Dermardirossian C. The microtubule-associated Rho activating factor GEF-H1 interacts with exocyst complex to regulate vesicle traffic. Dev Cell 2012; 23:397-411. [PMID: 22898781 DOI: 10.1016/j.devcel.2012.06.014] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 05/23/2012] [Accepted: 06/02/2012] [Indexed: 12/30/2022]
Abstract
The exocyst complex plays a critical role in targeting and tethering vesicles to specific sites of the plasma membrane. These events are crucial for polarized delivery of membrane components to the cell surface, which is critical for cell motility and division. Though Rho GTPases are involved in regulating actin dynamics and membrane trafficking, their role in exocyst-mediated vesicle targeting is not very clear. Herein, we present evidence that depletion of GEF-H1, a guanine nucleotide exchange factor for Rho proteins, affects vesicle trafficking. Interestingly, we found that GEF-H1 directly binds to exocyst component Sec5 in a Ral GTPase-dependent manner. This interaction promotes RhoA activation, which then regulates exocyst assembly/localization and exocytosis. Taken together, our work defines a mechanism for RhoA activation in response to RalA-Sec5 signaling and involvement of GEF-H1/RhoA pathway in the regulation of vesicle trafficking.
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Affiliation(s)
- Ritu Pathak
- Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
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38
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The serologically defined colon cancer antigen-3 interacts with the protein tyrosine phosphatase PTPN13 and is involved in the regulation of cytokinesis. Oncogene 2012; 32:4602-13. [PMID: 23108400 DOI: 10.1038/onc.2012.485] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 08/14/2012] [Accepted: 09/04/2012] [Indexed: 12/22/2022]
Abstract
Cytokinesis is the final step of cell division. Increasing evidence suggests failure of cytokinesis might contribute to the development of cancer. Here, we demonstrate that the serologically defined colon cancer antigen-3 (SDCCAG3) forms a complex with PTPN13, a protein tyrosine phosphatase known to be involved in the regulation of cytokinesis, carcinogenesis and tumor aggressiveness. We show that SDCCAG3 is a novel endosomal protein, primarily localized at the early/recycling endosomal compartment. SDCCAG3 undergoes dynamic localization during cell division with strong accumulation at the midbody during cytokinesis. Overexpression as well as downregulation correlates with the generation of multinucleate cells. Furthermore, we show interaction of SDCCAG3 with the Arf GTPase activating protein GIT1 (G protein-coupled receptor kinase interactor-1). Overexpression of an ArfGAP-negative version of GIT1 also results in an increased number of multinucleate cells suggesting regulation of Arf-mediated vesicular trafficking or signaling via SDCCAG3. Finally, we demonstrate that SDCCAG3 expression levels are elevated in colon cancers. In summary, we have established SDCCAG3 as a novel endosomal protein, which is involved in the regulation of cytokinesis.
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Izumiyama T, Minoshima S, Yoshida T, Shimizu N. A novel big protein TPRBK possessing 25 units of TPR motif is essential for the progress of mitosis and cytokinesis. Gene 2012; 511:202-17. [PMID: 23036704 DOI: 10.1016/j.gene.2012.09.061] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 09/07/2012] [Accepted: 09/20/2012] [Indexed: 10/27/2022]
Abstract
Through the comprehensive analysis of the genomic DNA sequence of human chromosome 22, we identified a novel gene of 702 kb encoding a big protein of 2481 amino acid residues, and named it as TPRBK (TPR containing big gene cloned at Keio). A novel protein TPRBK possesses 25 units of the TPR motif, which has been known to associate with a diverse range of biological functions. Orthologous genes of human TPRBK were found widely in animal species, from insecta to mammal, but not found in plants, fungi and nematoda. Northern blotting and RT-PCR analyses revealed that TPRBK gene is expressed ubiquitously in the human and mouse fetal tissues and various cell lines of human, monkey and mouse. Immunofluorescent staining of the synchronized monkey COS-7 cells with several relevant antibodies indicated that TPRBK changes its subcellular localization during the cell cycle: at interphase TPRBK locates on the centrosomes, during mitosis it translocates from spindle poles to mitotic spindles then to spindle midzone, and through a period of cytokinesis it stays on the midbody. Co-immunoprecipitation assay and immunofluorescent staining with adequate antibodies revealed that TPRBK binds to Aurora B, and those proteins together translocate throughout mitosis and cytokinesis. Treatments of cells with two drugs (Blebbistatin and Y-27632), that are known to inhibit the contractility of actin-myosin, disturbed the proper intracellular localization of TPRBK. Moreover, the knockdown of TPRBK expression by small interfering RNA (siRNA) suppressed the bundling of spindle midzone microtubules and disrupted the midbody formation, arresting the cells at G(2)+M phase. These observations indicated that a novel big protein TPRBK is essential for the formation and integrity of the midbody, hence we postulated that TPRBK plays a critical role in the progress of mitosis and cytokinesis during mammalian cell cycle.
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Affiliation(s)
- Tomohiro Izumiyama
- Advanced Research Center for Genome Super Power, Keio University, Tsukuba, Japan
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40
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Echard A. Phosphoinositides and cytokinesis: the "PIP" of the iceberg. Cytoskeleton (Hoboken) 2012; 69:893-912. [PMID: 23012232 DOI: 10.1002/cm.21067] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 08/20/2012] [Accepted: 08/21/2012] [Indexed: 12/21/2022]
Abstract
Phosphoinositides [Phosphatidylinositol (PtdIns), phosphatidylinositol 3-monophosphate (PtdIns3P), phosphatidylinositol 4-monophosphate (PtdIns4P), phosphatidylinositol 5-monophosphate (PtdIns5P), phosphatidylinositol 3,4-bisphosphate (PtdIns(3,4)P(2) ), phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P(2) ), phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2) ), and phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P(3) )] are lowly abundant acidic lipids found at the cytosolic leaflet of the plasma membrane and intracellular membranes. Initially discovered as precursors of second messengers in signal transduction, phosphoinositides are now known to directly or indirectly control key cellular functions, such as cell polarity, cell migration, cell survival, cytoskeletal dynamics, and vesicular traffic. Phosphoinositides actually play a central role at the interface between membranes and cytoskeletons and contribute to the identity of the cellular compartments by recruiting specific proteins. Increasing evidence indicates that several phosphoinositides, particularly PtdIns(4,5)P(2) , are essential for cytokinesis, notably after furrow ingression. The present knowledge about the specific phosphoinositides and phosphoinositide modifying-enzymes involved in cytokinesis will be first presented. The review of the current data will then show that furrow stability and cytokinesis abscission require that both phosphoinositide production and hydrolysis are regulated in space and time. Finally, I will further discuss recent mechanistic insights on how phosphoinositides regulate membrane trafficking and cytoskeletal remodeling for successful furrow ingression and intercellular bridge abscission. This will highlight unanticipated connections between cytokinesis and enzymes implicated in human diseases, such as the Lowe syndrome.
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Affiliation(s)
- Arnaud Echard
- Membrane Traffic and Cell Division Lab, Institut Pasteur, 28 rue du Dr Roux 75015 Paris, France; CNRS URA2582, Paris, France.
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41
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Giansanti MG, Fuller MT. What Drosophila spermatocytes tell us about the mechanisms underlying cytokinesis. Cytoskeleton (Hoboken) 2012; 69:869-81. [PMID: 22927345 DOI: 10.1002/cm.21063] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Revised: 08/13/2012] [Accepted: 08/17/2012] [Indexed: 12/21/2022]
Abstract
Cytokinesis separates the genomic material and organelles of a dividing cell equitably into two physically distinct daughter cells at the end of cell division. This highly choreographed process involves coordinated reorganization and regulated action of the actin and microtubule cytoskeletal systems, an assortment of motor proteins, and membrane trafficking components. Due to their large size, the ease with which exquisite cytological analysis may be performed on them, and the availability of numerous mutants and other genetic tools, Drosophila spermatocytes have provided an excellent system for exploring the mechanistic basis for the temporally programmed and precise spatially localized events of cytokinesis. Mutants defective in male meiotic cytokinesis can be easily identified in forward genetic screens by the production of multinucleate spermatids. In addition, the weak spindle assembly checkpoint in spermatocytes, which causes only a small delay of anaphase onset in the presence of unattached chromosomes, allows investigation of whether gene products required for spindle assembly and chromosome segregation are also involved in cytokinesis. Perhaps due to the large size of spermatocytes and the requirement for two rapid-fire rounds of division without intervening S or growth phases during meiosis, male meiotic mutants have also revealed much about molecular mechanisms underlying new membrane addition during cytokinesis. Finally, cell type-specific differences in the events that set up and complete cytokinesis are emerging from comparison of spermatocytes with cells undergoing mitosis either elsewhere in the organism or in tissue culture.
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Affiliation(s)
- Maria Grazia Giansanti
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie Università Sapienza di Roma, Piazzale A. Moro 5, Roma, Italy.
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42
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Smith CM, Chircop M. Clathrin-mediated endocytic proteins are involved in regulating mitotic progression and completion. Traffic 2012; 13:1628-41. [PMID: 22901037 DOI: 10.1111/tra.12001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 08/14/2012] [Accepted: 08/17/2012] [Indexed: 12/23/2022]
Abstract
A few proteins required for clathrin-mediated endocytosis (CME) are associated with successful completion of mitosis at distinct mitotic stages. Clathrin heavy chain (CHC) and epsin are required for chromosome segregation independent of their CME function and dynamin II (dynII) functions in the abscission stage of cytokinesis. In this study we screened for mitotic roles of eight CME proteins: CHC, α-adaptin, CALM, epsin, eps15, endophilin II (edpnII), syndapin II (sdpnII) and the GTPase dynII using a small interfering RNA targeting approach. All proteins, except for CALM, are associated with completion of the abscission stage of cytokinesis, suggesting that they function in this process in an endocytic-dependent manner. In support of this concept, overexpression of epsin(S357D), which blocks endocytosis, induced multinucleation. Moreover, six of them have a secondary role at earlier mitotic stages that is not dependent on their endocytic function: CHC, epsin and eps15 in chromosome segregation, and sdpnII, α-adaptin and CALM have a role in furrow ingression. Therefore, the role of endocytic proteins in mitosis is much broader than previously recognized.
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Affiliation(s)
- Charlotte M Smith
- Children's Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead, NSW, 2145, Australia
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43
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Belloni G, Sechi S, Riparbelli MG, Fuller MT, Callaini G, Giansanti MG. Mutations in Cog7 affect Golgi structure, meiotic cytokinesis and sperm development during Drosophila spermatogenesis. J Cell Sci 2012; 125:5441-52. [PMID: 22946051 DOI: 10.1242/jcs.108878] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The conserved oligomeric Golgi (COG) complex plays essential roles in Golgi function, vesicle trafficking and glycosylation. Deletions in the human COG7 gene are associated with a rare multisystemic congenital disorder of glycosylation that causes mortality within the first year of life. In this paper, we characterise the Drosophila orthologue of COG7 (Cog7). Loss-of-function Cog7 mutants are viable but male sterile. The Cog7 gene product is enriched in the Golgi stacks and in Golgi-derived structures throughout spermatogenesis. Mutations in the Cog7 gene disrupt Golgi architecture and reduce the number of Golgi stacks in primary spermatocytes. During spermiogenesis, loss of the Cog7 protein impairs the assembly of the Golgi-derived acroblast in spermatids and affects axoneme architecture. Similar to the Cog5 homologue, four way stop (Fws), Cog7 enables furrow ingression during cytokinesis. We show that the recruitment of the small GTPase Rab11 and the phosphatidylinositol transfer protein Giotto (Gio) to the cleavage site requires a functioning wild-type Cog7 gene. In addition, Gio coimmunoprecipitates with Cog7 and with Rab11 in the testes. Our results altogether implicate Cog7 as an upstream component in a gio-Rab11 pathway controlling membrane addition during cytokinesis.
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Affiliation(s)
- Giorgio Belloni
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie Università di Roma Sapienza, P.le A Moro 5, 00185 Roma, Italy
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44
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Short B. Clathrin helps maintain the centrosome's integrity. J Biophys Biochem Cytol 2012. [PMCID: PMC3514020 DOI: 10.1083/jcb.1984if] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Inactivating clathrin in S phase reveals the protein's involvement in centrosome maturation.
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45
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Abstract
In systems as diverse as yeast, slime mold and animal cells, the levels and distribution of phosphatidylinositol phosphates (PIPs) must be strictly regulated for successful cell cleavage. The precise mechanism by which PIPs function in this process remains unknown. Recent experiments are beginning to shed light on the cellular pathways in which PIPs make key contributions during cytokinesis. In particular, PIPs promote proper actin cytoskeletal organization and direct membrane trafficking in dividing cells. Future research will uncover temporal and spatial regulation of the different PIPs, thus elucidating their role in cytoskeletal and membrane events that drive cell cleavage.
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Affiliation(s)
- Julie A Brill
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Ontario M5G 1L7, Canada.
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46
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Foraker AB, Camus SM, Evans TM, Majeed SR, Chen CY, Taner SB, Corrêa IR, Doxsey SJ, Brodsky FM. Clathrin promotes centrosome integrity in early mitosis through stabilization of centrosomal ch-TOG. ACTA ACUST UNITED AC 2012; 198:591-605. [PMID: 22891263 PMCID: PMC3514040 DOI: 10.1083/jcb.201205116] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Clathrin inactivation during S phase destabilizes the microtubule-binding protein
ch-TOG, affecting its centrosomal localization and centrosome integrity during
early mitosis. Clathrin depletion by ribonucleic acid interference (RNAi) impairs mitotic
spindle stability and cytokinesis. Depletion of several clathrin-associated
proteins affects centrosome integrity, suggesting a further cell cycle function
for clathrin. In this paper, we report that RNAi depletion of CHC17 (clathrin
heavy chain 17) clathrin, but not the CHC22 clathrin isoform, induced centrosome
amplification and multipolar spindles. To stage clathrin function within the
cell cycle, a cell line expressing SNAP-tagged clathrin light chains was
generated. Acute clathrin inactivation by chemical dimerization of the SNAP-tag
during S phase caused reduction of both clathrin and ch-TOG (colonic, hepatic
tumor overexpressed gene) at metaphase centrosomes, which became fragmented.
This was phenocopied by treatment with Aurora A kinase inhibitor, suggesting a
centrosomal role for the Aurora A–dependent complex of clathrin, ch-TOG,
and TACC3 (transforming acidic coiled-coil protein 3). Clathrin inactivation in
S phase also reduced total cellular levels of ch-TOG by metaphase. Live-cell
imaging showed dynamic clathrin recruitment during centrosome maturation.
Therefore, we propose that clathrin promotes centrosome maturation by
stabilizing the microtubule-binding protein ch-TOG, defining a novel role for
the clathrin–ch-TOG–TACC3 complex.
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Affiliation(s)
- Amy B Foraker
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA 94143, USA
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47
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Pittman KJ, Skop AR. Anterior PAR proteins function during cytokinesis and maintain DYN-1 at the cleavage furrow in Caenorhabditis elegans. Cytoskeleton (Hoboken) 2012; 69:826-39. [PMID: 22887994 DOI: 10.1002/cm.21053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 07/16/2012] [Accepted: 07/17/2012] [Indexed: 12/25/2022]
Abstract
PAR proteins are key regulators of cellular polarity and have links to the endocytic machinery and the actin cytoskeleton. Our data suggest a unique role for PAR proteins in cytokinesis. We have found that at the onset of cytokinesis, anterior PAR-6 and posterior PAR-2 proteins are redistributed to the furrow membrane in a temporal and spatial manner. PAR-6 and PAR-2 localize to the furrow membrane during ingression but PAR-2-GFP is distinct in that it is excluded from the extreme tip of the furrow. Once the midbody has formed, PAR-2-GFP becomes restricted to the midbody region (the midbody plus the membrane flanking it). Depletion of both anterior PAR proteins, PAR-3 and PAR-6, led to an increase in multinucleate embryos, suggesting that the anterior PAR proteins are necessary during cytokinesis and that PAR-3 and PAR-6 function in cytokinesis may be partially redundant. Lastly, anterior PAR proteins play a role in the maintenance of DYN-1 in the cleavage furrow. Our data indicate that the PAR proteins are involved in the events that occur during cytokinesis and may play a role in promoting the membrane trafficking and remodeling events that occur during this time.
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Affiliation(s)
- Kelly J Pittman
- Laboratory of Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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48
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Abstract
Cytokinesis, the final step in cell division, partitions the contents of a single cell into two. In animal cells, cytokinesis occurs through cortical remodeling orchestrated by the anaphase spindle. Cytokinesis relies on a tight interplay between signaling and cellular mechanics and has attracted the attention of both biologists and physicists for more than a century. In this review, we provide an overview of four topics in animal cell cytokinesis: (a) signaling between the anaphase spindle and cortex, (b) the mechanics of cortical remodeling, (c) abscission, and (d) regulation of cytokinesis by the cell cycle machinery. We report on recent progress in these areas and highlight some of the outstanding questions that these findings bring into focus.
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Affiliation(s)
- Rebecca A Green
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093, USA.
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49
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BRCA2 localization to the midbody by filamin A regulates cep55 signaling and completion of cytokinesis. Dev Cell 2012; 23:137-52. [PMID: 22771033 DOI: 10.1016/j.devcel.2012.05.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 02/13/2012] [Accepted: 05/10/2012] [Indexed: 11/20/2022]
Abstract
Disruption of the BRCA2 tumor suppressor is associated with structural and numerical chromosomal defects. The numerical abnormalities in BRCA2-deficient cells may partly result from aberrations in cell division caused by disruption of BRCA2 during cytokinesis. Here we show that BRCA2 is a component of the midbody that is recruited through an interaction with Filamin A actin-binding protein. At the midbody, BRCA2 influences the recruitment of endosomal sorting complex required for transport (ESCRT)-associated proteins, Alix and Tsg101, and formation of CEP55-Alix and CEP55-Tsg101 complexes during abscission. Disruption of these BRCA2 interactions by cancer-associated mutations results in increased cytokinetic defects but has no effect on BRCA2-dependent homologous recombination repair of DNA damage. These findings identify a specific role for BRCA2 in the regulation of midbody structure and function, separate from DNA damage repair, that may explain in part the whole-chromosomal instability in BRCA2-deficient tumors.
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50
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Ma MPC, Chircop M. SNX9, SNX18 and SNX33 are required for progression through and completion of mitosis. J Cell Sci 2012; 125:4372-82. [PMID: 22718350 DOI: 10.1242/jcs.105981] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Mitosis involves considerable membrane remodelling and vesicular trafficking to generate two independent cells. Consequently, endocytosis and endocytic proteins are required for efficient mitotic progression and completion. Several endocytic proteins also participate in mitosis in an endocytosis-independent manner. Here, we report that the sorting nexin 9 (SNX9) subfamily members - SNX9, SNX18 and SNX33 - are required for progression and completion of mitosis. Depletion of any one of these proteins using siRNA induces multinucleation, an indicator of cytokinesis failure, as well as an accumulation of cytokinetic cells. Time-lapse microscopy on siRNA-treated cells revealed a role for SNX9 subfamily members in progression through the ingression and abscission stages of cytokinesis. Depletion of these three proteins disrupted MRLC(S19) localization during ingression and recruitment of Rab11-positive recycling endosomes to the intracellular bridge between nascent daughter cells. SNX9 depletion also disrupted the localization of Golgi during cytokinesis. Endocytosis of transferrin was blocked during cytokinesis by depletion of the SNX9 subfamily members, suggesting that these proteins participate in cytokinesis in an endocytosis-dependent manner. In contrast, depletion of SNX9 did not block transferrin uptake during metaphase but did delay chromosome alignment and segregation, suggesting that SNX9 plays an additional non-endocytic role at early mitotic stages. We conclude that SNX9 subfamily members are required for mitosis through both endocytosis-dependent and -independent processes.
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Affiliation(s)
- Maggie P C Ma
- Children's Medical Research Institute, The University of Sydney, Westmead, NSW 2145, Australia
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