DOCSLIB.ORG

NUCLEAR LAMINA ASSEMBLY, SYNTHESIS and DISAGGREGATION DURING the CELL CYCLE in SYNCHRONIZED Hela CELLS

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
NUCLEAR LAMINA ASSEMBLY, SYNTHESIS and DISAGGREGATION DURING the CELL CYCLE in SYNCHRONIZED Hela CELLS J. Cell Sci. 47, as-53 (1981) 25 Printed in Great Britain © Company of Biologists Limited 1081 NUCLEAR LAMINA ASSEMBLY, SYNTHESIS AND DISAGGREGATION DURING THE CELL CYCLE IN SYNCHRONIZED HeLa CELLS ERICH JOST* AND ROBERT T. JOHNSON European Molecular Biology Laboratory, D69 Heidelberg, Federal Republic of Germany, and Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, England. SUMMARY The pattern of assembly, synthesis and disaggregation of the nuclear envelope-associated lamina in synchronized HeLa cells has been examined by means of immunofluorescence microscopy of cell preparations treated with antibody to lamina polypeptide LP67 or lamin B, using the nomenclature of Gerace and Blobel. During the cell cycle the distribution of lamina polypeptide varies dramatically. Three distinct stages can be detected with respect to its location and synthesis: (1) Lamina polypeptide is cytoplasmically distributed during cell division particularly at the time of complete nuclear envelope breakdown. At telophase it is reassembled and becomes associated with regions of the chromosome surface. This process continues into early Glt lamina polypeptide associating progressively with the outer surface of the chromosomes; simultaneously its cytoplasmic concentration is reduced. The traffic of antigen from cytoplasm to the chromosomes is highest between telophase and Gt but continues at a reduced rate during G1. Inhibition of protein synthesis during division and G^ does not inhibit G1 lamina reforma- tion, suggesting that the Gj lamina is constructed from depolymerized cytoplasmically-stored polypeptide derived from the previous cell cycle. (2) Lamin B is synthesized in S-phase. The protein is rapidly accumulated at the nuclear periphery during the doubling of the nuclear surface. There is very little if any cytoplasmic location of lamina polypeptide in <S-phase cells. The 5-phase pattern of lamina distribution persists through early and mid G,. (3) Towards the end of G, and particularly with the onset of prophase, the nuclear membrane-bound lamina is released into the cytoplasm over approximately 30 min. (Fusion between metaphase and either Gx or .S-phase cells also results in the depolymerization of lamin B within 30 min.) Lamina polypeptides appear in the cytoplasm before the nuclear enve- lope has disappeared, and protein synthesis in Gt is required for complete lamina disaggregation. Lamina reformation in late mitosis and the polarity of its appearance in the telophase cell can be perturbed by treatment with colcemid or low temperature so that lamina is induced to associate with metaphase and anaphase chromosomes. In the absence of spindle microtubules lamina reformation may proceed around the surface of whole chromosomes, leading to the formation of micronuclei in Gl cells. We propose that in the normal cell nuclear envelope formation at telophase is related to the terminal distribution of cytoskeleton structures such that lamina is laid down only on the outer surface of the telophase genome beginning at the telomeric chromosome ends adjacent to the remaining mitotic fibres of the cleavage furrow. INTRODUCTION The 3 major polypeptides of the pore complex-lamina fraction of the nuclear envelope are the elements of a unique structural framework in the eukaryotic cell • Present address: Department of Genetics, University of Giessen, Heiuvich-Buff-Ring 58-62, D63 Giessen, F.R.G. 26 E. Jost and R. T. Johnson (for reviews see: Franke, 1974; Franke & Scheer, 1974). Topologically the nuclear pore complex-lamina fraction underlies the inner nuclear membrane and connects chromatin to the nuclear envelope. Experimental evidence for a lamina-chromatin interaction comes from studies of remnant structural components of nuclei after removal of large amounts of nuclear proteins and DNA by a procedure introduced by Mirsky & Ris (1951). The remaining structure, the nuclear 'matrix' or nuclear skeleton, has been studied in a variety of cells (e.g. Shankara Narayam, Steele, Smetana & Busch, 1967; Berezney & Coffey, 1974, 1977; Comings & Okada, 1976; Scheer et al. 1976; Wunderlich & Herlan, 1977; Miller, Huang & Pogo, 1978; Grebanier & Pogo, 1979; Pardoll, Vosenstein & Coffey, 1980). DNA remains asso- ciated with these structures in a specific manner and the DNA-binding properties of nuclear matrix polypeptides have been analysed by filter binding assays (Comings & Wallack, 1978), and by protein blotting (Bowen, Steinberg, Laemmli & Weintraub, 1980). In mouse hepatocytes it has been determined cytophotometrically that more than 50 % of the total nuclear DNA is located within 1 /tm of the nuclear envelope (Kiefer, Kiefer & Sandritter, 1971). DNA which remains attached to the nuclear envelope when it is isolated is enriched in A-T sequences (see review: Franke, 1974; Comings & Wallack, 1978) and at least partially organized in loops (Zentgraf, Falk & Franke, 1975). Human DNA which is intact and organized in domains but largely free of protein can be isolated from cells by preparing nucleoids. Nucleoids are structures resembling nuclei, which are obtained by gently lysing cells in solutions containing non-ionic detergents and high salt concentrations. These structures sediment in gradients con- taining intercalating agents in a manner characteristic of superhelical DNA (Cook & Brazell, 1975, 1976, 1977, 1978; Cook, Brazell & Jost, 1976; Warren & Cook, 1978; McCready, Akrigg & Cook, 1979). Nucleoids are largely depleted of proteins (Cook et al. 1976; Levine, Jost & Cook, 1978), but associated with them are components of the nuclear pore complex-lamina fraction (Ely, D'Arcy & Jost, 1978). Lamina poly- peptides may help to stabilize nucleoids and may form the basis for the partition of the DNA molecule into a series of quasi circular domains. A large body of information about the chemistry of the 3 major lamina poly- peptides has been collected by Lam & Kaspar (1979a, b). Because of the differences in molecular weight determinations among the groups working with the 3 lamina polypeptides, in future we will refer to the polypeptides as lamin A, B and C following the proposal of Gerace & Blobel (1980). Lamin B exists as 2 electrophoretic- ally distinct polymeric species both of which are probably trimers and which differ in the extent of inter- or intramolecular disulphide bridges. Lamin A exists in di-, tetra- penta- and higher oligomeric forms, but lamin C only as monomer. Lamins A and C have close sequence homology whereas lamin B is distinctly different. The proteins are highly hydrophobic and the smallest polypeptide (lamin C) is pre- ferentially phosphorylated by an intrinsic membrane protein kinase (Lam & Kaspar, 19796). The 3 polypeptides extracted from rat liver nuclei and isolated by SDS-gel electro- phoresis were used to immunize chickens and the specificity of each antiserum was Nuclear lamina in synchronized HeLa cells 27 tested by means of immunofluorescence light microscopy and 'peroxidase'-electron microscopy using a variety of eukaryotic cells. Treatment with the antisera resulted in specific immunofluorescent staining of the proteinaceous lamina underlying the nuclear envelope (Ely et al. 1978; Krohne et al. 1978; Gerace, Blum & Blobel, 1978; Gerace & Blobel, 1980). The antisera produced a similar intensity of fluorescent labelling in the majority of cells tested with the exception of chicken fibroblasts which could not be extensively decorated with the 3 antisera, and chick erythrocytes, which showed no envelope-specific fluorescence (Jost et al. 1979). The individual location of the 3 polypeptides in the nuclear pore complex-lamina fraction is obscured by a strong cross-reaction between the 3 antisera and the antigens (Gerace et al. 1978; Ely et al. 1978) which may be explained on the basis of sequence homologies found among the polypeptides A and C (Lam & Kaspar, 1979 a), and possibly, A, C and B. For this reason we restrict our attention to results obtained with anti-LP67 or anti-lamin B as the marker polypeptide. The relationship between the nuclear matrix and the lamina is not entirely clear. The 2 prominent nuclear matrix polypeptides of molecular weight 66 and 62 kD (Long, Huang & Pogo, 1979) and polypeptides described by Berezney & Coffey (1974, 1977) as prominent components of the rat liver matrix are the major poly- peptides of the rat liver lamina and are located exclusively at the periphery of the nucleus when the nuclear envelope is present in interphase (Ely et al. 1978; Krohne et al. 1978; Jost et al. 1979; Gerace et al. 1978; Gerace & Blobel, 1980). Functionally, the peripheral nuclear 'matrix' and the lamina may be identical. The matrix has been identified as the attachment site of DNA replication points (Dijkwel, Mullenders & Wanka, 1979; Pardoll, Vogelstein & Coffey, 1980), though its role in other aspects of DNA behaviour such as repair or transcription is not certain. The morphogenesis of the nuclear lamina is closely related to the cell cycle as demonstrated by the use of antibodies directed against the 3 lamina polypeptides prepared by us (Ely et al. 1978; Krohne et al. 1978; Jost, D'Arcy & Ely, 1979), and by Gerace, Blum & Blobel (Gerace et al. 1978; Gerace & Blobel, 1980). In the present study, we extend our investigations of nuclear envelope dynamics by observing the distribution of lamin B in synchronized cells since this allows a more precise correlation to be made of the disappearance and reappearance of the nuclear envelope in a large number of dividing cells in identified stages
Load more

Recommended publications
  • Revealing the Mechanism of Xist-Mediated Silencing
    Revealing the Mechanism of Xist-mediated Silencing Thesis by Chun-Kan Chen In Partial Fulfillment of the Requirements for the degree of Doctor of Philosophy CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California 2018 Defended November 1, 2017 ii 2017 Chun-Kan Chen ORCID: 0000-0002-1194-9137 iii ACKNOWLEDGEMENTS First of all, I’d like to thank my great mentor, Dr. Mitch Guttman (California Institute of Technology, Pasadena, CA), who led me to become an independent researcher and gave me valuable advice that guided me to accomplish this thesis. He has always been supportive of my future plans and career goals. I really enjoyed every discussion we have had. We often generated some interesting ideas for projects during our discussions. I would also like to send my thanks to my lab mates, Amy Chow, Mario Blanco, and Erik Aznauryan, who helped me with many experiments to move the project forward. I’d like to acknowledge Dr. Kathrin Plath (University of California, Los Angeles, Los Angeles, CA) for the collaboration and his critical comments on this project. Also, I want to thank Jesse Engreitz and Patrick McDonel, who provided helpful comments and suggestions to the project. I want to thank my parents, brother, and parents-in-law who provided both instrumental and emotional support to assist me in completing my Ph.D. degree. I also want to thank my friends, Lily Chen, Pei-Ying Lin, Tzu-Yao Wang, and Wei Li, for giving me valuable social support during my years in graduate school. Last but not least, I would like to send my special thanks to my wife, Christine Juang, who has always been supportive.
    [Show full text]
  • Upon Microbial Challenge, Human Neutrophils Undergo Rapid Changes in Nuclear Architecture and Chromatin Folding to Orchestrate an Immediate Inflammatory Gene Program
    Downloaded from genesdev.cshlp.org on October 5, 2021 - Published by Cold Spring Harbor Laboratory Press Upon microbial challenge, human neutrophils undergo rapid changes in nuclear architecture and chromatin folding to orchestrate an immediate inflammatory gene program Matthew Denholtz,1,5 Yina Zhu,1,5 Zhaoren He,1 Hanbin Lu,1 Takeshi Isoda,1,4 Simon Döhrmann,2 Victor Nizet,2,3 and Cornelis Murre1 1Division of Biological Sciences, Department of Molecular Biology, University of California at San Diego, La Jolla, California 92039, USA; 2Department of Pediatrics, University of California at San Diego School of Medicine, La Jolla, California 92093, USA; 3Skaggs School of Pharmaceutical Sciences, University of California at San Diego, La Jolla, California 92093, USA Differentiating neutrophils undergo large-scale changes in nuclear morphology. How such alterations in structure are established and modulated upon exposure to microbial agents is largely unknown. Here, we found that prior to encounter with bacteria, an armamentarium of inflammatory genes was positioned in a transcriptionally passive environment suppressing premature transcriptional activation. Upon microbial exposure, however, human neu- trophils rapidly (<3 h) repositioned the ensemble of proinflammatory genes toward the transcriptionally permissive compartment. We show that the repositioning of genes was closely associated with the swift recruitment of cohesin across the inflammatory enhancer landscape, permitting an immediate transcriptional response upon bacterial exposure. We found that activated enhancers, marked by increased deposition of H3K27Ac, were highly enriched for cistromic elements associated with PU.1, CEBPB, TFE3, JUN, and FOSL2 occupancy. These data reveal how upon microbial challenge the cohesin machinery is recruited to an activated enhancer repertoire to instruct changes in chromatin folding, nuclear architecture, and to activate an inflammatory gene program.
    [Show full text]
  • Nuclear Domains
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Cold Spring Harbor Laboratory Institutional Repository CELL SCIENCE AT A GLANCE 2891 Nuclear domains dynamic structures and, in addition, nuclear pore complex has been shown to rapid protein exchange occurs between have a remarkable substructure, in which David L. Spector many of the domains and the a basket extends into the nucleoplasm. Cold Spring Harbor Laboratory, One Bungtown nucleoplasm (Misteli, 2001). An The peripheral nuclear lamina lies Road, Cold Spring Harbor, NY 11724, USA extensive effort is currently underway by inside the nuclear envelope and is (e-mail: [email protected]) numerous laboratories to determine the composed of lamins A/C and B and is biological function(s) associated with thought to play a role in regulating Journal of Cell Science 114, 2891-2893 (2001) © The Company of Biologists Ltd each domain. The accompanying poster nuclear envelope structure and presents an overview of commonly anchoring interphase chromatin at the The mammalian cell nucleus is a observed nuclear domains. nuclear periphery. Internal patches of membrane-bound organelle that contains lamin protein are also present in the the machinery essential for gene The nucleus is bounded by a nuclear nucleoplasm (Moir et al., 2000). The expression. Although early studies envelope, a double-membrane structure, cartoon depicts much of the nuclear suggested that little organization exists of which the outer membrane is envelope/peripheral lamina as within this compartment, more contiguous with the rough endoplasmic transparent, so that internal structures contemporary studies have identified an reticulum and is often studded with can be more easily observed.
    [Show full text]
  • Nuclear Envelope Laminopathies: Evidence for Developmentally Inappropriate Nuclear Envelope-Chromatin Associations
    Nuclear Envelope Laminopathies: Evidence for Developmentally Inappropriate Nuclear Envelope-Chromatin Associations by Jelena Perovanovic M.S. in Molecular Biology and Physiology, September 2009, University of Belgrade M.Phil. in Molecular Medicine, August 2013, The George Washington University A Dissertation submitted to The Faculty of The Columbian College of Arts and Sciences of The George Washington University in partial fulfillment of the requirements for the degree of Doctor of Philosophy August 31, 2015 Dissertation directed by Eric P. Hoffman Professor of Integrative Systems Biology The Columbian College of Arts and Sciences of The George Washington University certifies that Jelena Perovanovic has passed the Final Examination for the degree of Doctor of Philosophy as of May 5, 2015. This is the final and approved form of the dissertation. Nuclear Envelope Laminopathies: Evidence for Developmentally Inappropriate Nuclear Envelope-Chromatin Associations Jelena Perovanovic Dissertation Research Committee: Eric P. Hoffman, Professor of Integrative Systems Biology, Dissertation Director Anamaris Colberg-Poley, Professor of Integrative Systems Biology, Committee Member Robert J. Freishtat, Associate Professor of Pediatrics, Committee Member Vittorio Sartorelli, Senior Investigator, National Institutes of Health, Committee Member ii © Copyright 2015 by Jelena Perovanovic All rights reserved iii Acknowledgments I am deeply indebted to countless individuals for their support and encouragement during the past five years of graduate studies. First and foremost, I would like to express my gratitude to my mentor, Dr. Eric P. Hoffman, for his unwavering support and guidance, and keen attention to my professional development. This Dissertation would not have been possible without the critical input he provided and the engaging environment he created.
    [Show full text]
  • Dynamic Force-Induced Direct Dissociation of Protein Complexes in a Nuclear Body in Living Cells
    ARTICLE Received 13 Jan 2012 | Accepted 26 Apr 2012 | Published 29 May 2012 DOI: 10.1038/ncomms1873 Dynamic force-induced direct dissociation of protein complexes in a nuclear body in living cells Yeh-Chuin Poh1, Sergey P. Shevtsov2, Farhan Chowdhury1, Douglas C. Wu1, Sungsoo Na3, Miroslav Dundr2 & Ning Wang1 Despite past progress in understanding mechanisms of cellular mechanotransduction, it is unclear whether a local surface force can directly alter nuclear functions without intermediate biochemical cascades. Here we show that a local dynamic force via integrins results in direct displacements of coilin and SMN proteins in Cajal bodies and direct dissociation of coilin-SMN associated complexes. Spontaneous movements of coilin increase more than those of SMN in the same Cajal body after dynamic force application. Fluorescence resonance energy transfer changes of coilin-SMN depend on force magnitude, an intact F-actin, cytoskeletal tension, Lamin A/C, or substrate rigidity. Other protein pairs in Cajal bodies exhibit different magnitudes of fluorescence resonance energy transfer. Dynamic cyclic force induces tiny phase lags between various protein pairs in Cajal bodies, suggesting viscoelastic interactions between them. These findings demonstrate that dynamic force-induced direct structural changes of protein complexes in Cajal bodies may represent a unique mechanism of mechanotransduction that impacts on nuclear functions involved in gene expression. 1 Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Champaign, Illinois 61801, USA. 2 Department of Cell Biology, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064, USA. 3 Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indiana 46202, USA.
    [Show full text]
  • Nucleolus: a Central Hub for Nuclear Functions Olga Iarovaia, Elizaveta Minina, Eugene Sheval, Daria Onichtchouk, Svetlana Dokudovskaya, Sergey Razin, Yegor Vassetzky
    Nucleolus: A Central Hub for Nuclear Functions Olga Iarovaia, Elizaveta Minina, Eugene Sheval, Daria Onichtchouk, Svetlana Dokudovskaya, Sergey Razin, Yegor Vassetzky To cite this version: Olga Iarovaia, Elizaveta Minina, Eugene Sheval, Daria Onichtchouk, Svetlana Dokudovskaya, et al.. Nucleolus: A Central Hub for Nuclear Functions. Trends in Cell Biology, Elsevier, 2019, 29 (8), pp.647-659. 10.1016/j.tcb.2019.04.003. hal-02322927 HAL Id: hal-02322927 https://hal.archives-ouvertes.fr/hal-02322927 Submitted on 18 Nov 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Nucleolus: A Central Hub for Nuclear Functions Olga Iarovaia, Elizaveta Minina, Eugene Sheval, Daria Onichtchouk, Svetlana Dokudovskaya, Sergey Razin, Yegor Vassetzky To cite this version: Olga Iarovaia, Elizaveta Minina, Eugene Sheval, Daria Onichtchouk, Svetlana Dokudovskaya, et al.. Nucleolus: A Central Hub for Nuclear Functions. Trends in Cell Biology, Elsevier, 2019, 29 (8), pp.647-659. 10.1016/j.tcb.2019.04.003. hal-02322927 HAL Id: hal-02322927 https://hal.archives-ouvertes.fr/hal-02322927 Submitted on 18 Nov 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not.
    [Show full text]
  • Separate Roles for Chromatin and Lamins in Nuclear Mechanics
    Nucleus ISSN: 1949-1034 (Print) 1949-1042 (Online) Journal homepage: https://www.tandfonline.com/loi/kncl20 Separate roles for chromatin and lamins in nuclear mechanics Andrew D. Stephens, Edward J. Banigan & John F. Marko To cite this article: Andrew D. Stephens, Edward J. Banigan & John F. Marko (2018) Separate roles for chromatin and lamins in nuclear mechanics, Nucleus, 9:1, 119-124, DOI: 10.1080/19491034.2017.1414118 To link to this article: https://doi.org/10.1080/19491034.2017.1414118 © 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group© Andrew D. Stephens, Edward J. Banigan and John F. Marko Accepted author version posted online: 11 Dec 2017. Published online: 28 Dec 2017. Submit your article to this journal Article views: 1662 View related articles View Crossmark data Citing articles: 13 View citing articles Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=kncl20 NUCLEUS 2018, VOL. 9, NO. 1, 119–124 https://doi.org/10.1080/19491034.2017.1414118 EXTRA VIEW Separate roles for chromatin and lamins in nuclear mechanics Andrew D. Stephens a, Edward J. Baniganb,c, and John F. Markoa,b aDepartment of Molecular Biosciences, Northwestern University, Evanston, Illinois, USA; bDepartment of Physics and Astronomy, Northwestern University, Evanston, Illinois, USA; cInstitute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts ABSTRACT ARTICLE HISTORY The cell nucleus houses, protects, and arranges the genome within the cell. Therefore, nuclear Received 31 August 2017 mechanics and morphology are important for dictating gene regulation, and these properties are Revised 29 November 2017 perturbed in many human diseases, such as cancers and progerias.
    [Show full text]
  • Functional Studies of Nuclear Envelope-Associated Proteins in Saccharomyces Cerevisiae
    Functional studies of nuclear envelope-associated proteins in Saccharomyces cerevisiae Ida Olsson Stockholm University © Ida Olsson, Stockholm 2008 ISBN 978-91-7155-666-0, pp 1-58 Typesetting: Intellecta Docusys Printed in Sweden by Universitetsservice US-AB, Stockholm 2008 Distributor: Department of Biochemistry and Biophysics, Stockholm University To Carl with love ABSTRACT Proteins of the nuclear envelope play important roles in a variety of cellular processes e.g. transport of proteins between the nucleus and cytoplasm, co- ordination of nuclear and cytoplasmic events, anchoring of chromatin to the nuclear periphery and regulation of transcription. Defects in proteins of the nuclear envelope and the nuclear pore complexes have been related to a number of human diseases. To understand the cellular functions in which nuclear envelope proteins participate it is crucial to map the functions of these proteins. The present study was done in order to characterize the role of three different proteins in functions related to the nuclear envelope in the yeast Saccharo- myces cerevisiae. The arginine methyltransferase Rmt2 was demonstrated to associate with proteins of the nuclear pore complexes and to influence nu- clear export. In addition, Rmt2 was found to interact with the Lsm4 protein involved in RNA degradation, splicing and ribosome biosynthesis. These results provide support for a role of Rmt2 at the nuclear periphery and poten- tially in nuclear transport and RNA processing. The integral membrane pro- tein Cwh43 was localized to the inner nuclear membrane and was also found at the nucleolus. A nuclear function for Cwh43 was demonstrated by its abil- ity to bind DNA in vitro.
    [Show full text]
  • Condensins Exert Force on Chromatin-Nuclear Envelope Tethers to Mediate Nucleoplasmic Reticulum Formation in Drosophila Melanogaster
    INVESTIGATION Condensins Exert Force on Chromatin-Nuclear Envelope Tethers to Mediate Nucleoplasmic Reticulum Formation in Drosophila melanogaster Julianna Bozler,* Huy Q. Nguyen,* Gregory C. Rogers,† and Giovanni Bosco*,1 *Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755, and †Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724 ABSTRACT Although the nuclear envelope is known primarily for its role as a boundary between the KEYWORDS nucleus and cytoplasm in eukaryotes, it plays a vital and dynamic role in many cellular processes. Studies of nuclear nuclear structure have revealed tissue-specific changes in nuclear envelope architecture, suggesting that its architecture three-dimensional structure contributes to its functionality. Despite the importance of the nuclear envelope, chromatin force the factors that regulate and maintain nuclear envelope shape remain largely unexplored. The nuclear nucleus envelope makes extensive and dynamic interactions with the underlying chromatin. Given this inexorable chromatin link between chromatin and the nuclear envelope, it is possible that local and global chromatin organization compaction reciprocally impact nuclear envelope form and function. In this study, we use Drosophila salivary glands to nuclear envelope show that the three-dimensional structure of the nuclear envelope can be altered with condensin II- mediated chromatin condensation. Both naturally occurring and engineered chromatin-envelope interac- tions are sufficient to allow chromatin compaction forces to drive distortions of the nuclear envelope. Weakening of the nuclear lamina further enhanced envelope remodeling, suggesting that envelope struc- ture is capable of counterbalancing chromatin compaction forces. Our experiments reveal that the nucle- oplasmic reticulum is born of the nuclear envelope and remains dynamic in that they can be reabsorbed into the nuclear envelope.
    [Show full text]
  • Integrins As New Governors of Nuclear Alterations?
    cancers Review Inside the Cell: Integrins as New Governors of Nuclear Alterations? Elena Madrazo 1,2, Andrea Cordero Conde 2 and Javier Redondo-Muñoz 1,2,* 1 Section of Immuno-oncology, Instituto de Investigación Sanitaria Gregorio Marañón, 28007 Madrid, Spain; [email protected] 2 Department of Immunology, Hospital 12 de Octubre Health Research Institute (imas12), Complutense University School of Medicine, 28040 Madrid, Spain; [email protected] * Correspondence: [email protected]; Tel.: +34-913-941-642 Academic Editor: Helen M. Sheldrake Received: 16 May 2017; Accepted: 4 July 2017; Published: 6 July 2017 Abstract: Cancer cell migration is a complex process that requires coordinated structural changes and signals in multiple cellular compartments. The nucleus is the biggest and stiffest organelle of the cell and might alter its physical properties to allow cancer cell movement. Integrins are transmembrane receptors that mediate cell-cell and cell-extracellular matrix interactions, which regulate numerous intracellular signals and biological functions under physiological conditions. Moreover, integrins orchestrate changes in tumor cells and their microenvironment that lead to cancer growth, survival and invasiveness. Most of the research efforts have focused on targeting integrin-mediated adhesion and signaling. Recent exciting data suggest the crucial role of integrins in controlling internal cellular structures and nuclear alterations during cancer cell migration. Here we review the emerging role of integrins in nuclear biology. We highlight increasing evidence that integrins are critical for changes in multiple nuclear components, the positioning of the nucleus and its mechanical properties during cancer cell migration. Finally, we discuss how integrins are integral proteins linking the plasma membrane and the nucleus, and how they control cell migration to enable cancer invasion and infiltration.
    [Show full text]
  • A CTG Repeat-Selective Chemical Screen Identifies Microtubule Inhibitors As Selective Modulators of Toxic CUG RNA Levels
    A CTG repeat-selective chemical screen identifies microtubule inhibitors as selective modulators of toxic CUG RNA levels Kaalak Reddya,b, Jana R. Jenquina,b, Ona L. McConnella, John D. Clearya,b, Jared I. Richardsona,b, Belinda S. Pintoa, Maja C. Haerlea, Elizabeth Delgadoa,c, Lori Plancoa,b, Masayuki Nakamorid, Eric T. Wanga,c, and J. Andrew Berglunda,b,1 aCenter for NeuroGenetics, University of Florida College of Medicine, Gainesville, FL 32610; bThe RNA Institute, University at Albany, State University of New York, Albany, NY 12222; cDepartment of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, FL 32610; and dDepartment of Neurology, Osaka University Graduate School of Medicine, 565-0871 Osaka, Japan Edited by Shuying Sun, Johns Hopkins University School of Medicine, Baltimore, MD, and accepted by Editorial Board Member Michael F. Summers September 7, 2019 (received for review February 4, 2019) A CTG repeat expansion in the DMPK gene is the causative mutation splice site by using antisense oligonucleotides to repress inclusion of myotonic dystrophy type 1 (DM1). Transcription of the expanded of this alternative exon restored muscle chloride channel protein CTG repeat produces toxic gain-of-function CUG RNA, leading to levels and eliminated myotonia in DM1 cells and mouse models disease symptoms. A screening platform that targets production (12). Hence, missplicing observed in DM1 is an important bio- or stability of the toxic CUG RNA in a selective manner has the marker for disease severity as well as for evaluating the efficacy of potential to provide new biological and therapeutic insights. A therapeutic interventions. DM1 HeLa cell model was generated that stably expresses a toxic Currently, there are no Food and Drug Administration (FDA)- r(CUG)480 and an analogous r(CUG)0 control from DMPK and was approved disease-targeting treatments for myotonic dystrophy.
    [Show full text]
  • Observation of Nuclei Reassembled from Demembranated Xenopus Sperm Nuclei and Analysis of Their Lamina Com- Ponents
    Cell Research(1994),4, 163–172 Observation of nuclei reassembled from demembranated Xenopus sperm nuclei and analysis of their lamina com- ponents QU JI A N , C H U A N M A O ZHANG, Z H O N G H E ZHAI. College of Life Sciences, Beijing University, Beijing 100871, China. ABSTRACT A cell-free preparation obtained from extracts of ac- tivated Xenopus laevis eggs induced chromatin deconden- sation and nuclear formation from demembranated Xeno- pus sperm nuclei. Electron microscopy revealed that the reassembled nucleus had a double-layered nuclear mem- brane, nuclear pore complexes, and decondensed chro- matin etc. Indirect immunofluorescence analysis demon- strated the presence of lamina in newly assembled nu- clei. Western-blotting results showed that lamin LII was present in egg extracts and in lamina of the reassembled nuclei which were previously reported to contain only egg derived lamin LIII. Key words: Nuclear assembly in vitro, Xenopus laevis, Lamina. INTRODUCTION Following the pioneer work of Lokha and Masui[1, 2], studies using cell-free system have greatly enriched our knowledge about the events during cell cycle. Extracts derived from activated Xenopus laevis eggs able to asemble nuclei around exoge- neous naked DNA, isolated chromosomes and demembranated sperm chromatin have been widely used to study the pathways and biochemistry of nuclear envelope and pore complexes assembly, lamina formation, DNA replication and nuclear cytoplas- mic transportation[3-6]. Meanwhile, extracts prepared from mataphase eggs were adopted to study spindle organization and nuclear disassembly[7-10]. Plenty of in- formation on cell cycle regulation concerning nuclear reassembly and mitosis has also been obtained from the studies using cell-free system[9, 10].
    [Show full text]