DOCSLIB.ORG

Actin Reduction by Msrb2 Is a Key Component of the Cytokinetic Abscission Checkpoint and Prevents Tetraploidy

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Actin Reduction by Msrb2 Is a Key Component of the Cytokinetic Abscission Checkpoint and Prevents Tetraploidy Actin reduction by MsrB2 is a key component of the cytokinetic abscission checkpoint and prevents tetraploidy Jian Baia,b, Hugo Wiolandc, Tamara Advedissiana, Frédérique Cuveliera, Guillaume Romet-Lemonnec, and Arnaud Echarda,1 aMembrane Traffic and Cell Division Laboratory, Institut Pasteur, UMR3691, CNRS, F-75015 Paris, France; bCollège Doctoral, Sorbonne Université, F-75005 Paris, France; and cUniversité de Paris, CNRS, Institut Jacques Monod, F-75013 Paris, France Edited by Thomas D. Pollard, Yale University, New Haven, CT, and approved January 8, 2020 (received for review July 7, 2019) Abscission is the terminal step of cytokinesis leading to the physical promotes local F-actin clearance, ESCRT-III recruitment, and separation of the daughter cells. In response to the abnormal abscission. presence of lagging chromatin between dividing cells, an evolution- There are nevertheless physiological conditions in which ab- arily conserved abscission/NoCut checkpoint delays abscission and scission is delayed, notably when the abscission checkpoint/ prevents formation of binucleated cells by stabilizing the cytokinetic NoCut checkpoint is activated (10, 29–36). This evolutionarily intercellular bridge (ICB). How this bridge is stably maintained conserved checkpoint depends on several kinases, including for hours while the checkpoint is activated is poorly understood Aurora B, and is triggered by different cytokinetic stresses, such and has been proposed to rely on F-actin in the bridge region. Here, as persisting, ultrathin DNA bridges (UFBs) and lagging chro- we show that actin polymerization is indeed essential for stabilizing matin positive for nuclear envelop markers (hereafter referred as the ICB when lagging chromatin is present, but not in normal “chromatin bridges”) within the ICB, as well as high membrane dividing cells. Mechanistically, we found that a cytosolic pool of tension or nuclear pore defects (32, 37–47). Chromatin bridges human methionine sulfoxide reductase B2 (MsrB2) is strongly spanning between the two daughter nuclei across the ICB can recruited at the midbody in response to the presence of lagging result from DNA replication stress, incomplete DNA decatenation, chromatin and functions within the ICB to promote actin polymer- or telomere attrition and activate the checkpoint to delay ab- CELL BIOLOGY ization there. Consistently, in MsrB2-depleted cells, F-actin levels are scission, presumably giving additional time for resolving these decreased in ICBs, and dividing cells with lagging chromatin become abnormalities (10, 33–35, 48). A defective checkpoint results in binucleated as a consequence of unstable bridges. We further cytokinetic failure and binucleated cells (tetraploidy) (32, 38, 44) demonstrate that MsrB2 selectively reduces oxidized actin mono- or chromosome breaks and DNA damage (40, 43, 45–47, 49), mers and thereby counteracts MICAL1, an enzyme known to and these distinct outcomes apparently depend on which com- depolymerize actin filaments by direct oxidation. Finally, MsrB2 ponent of the checkpoint has been removed for reasons that are colocalizes and genetically interacts with the checkpoint components not fully understood (10, 33, 35, 36). In several instances, ex- Aurora B and ANCHR, and the abscission delay upon checkpoint perimental inactivation of the checkpoint (e.g., Aurora B or activation by nuclear pore defects also depends on MsrB2. Alto- gether, this work reveals that actin reduction by MsrB2 is a key Significance component of the abscission checkpoint that favors F-actin polymer- ization and limits tetraploidy, a starting point for tumorigenesis. Cytokinesis concludes cell division by physically separating the actin | cytoskeleton | cytokinesis | oxidoreduction | abscission checkpoint daughter cells. Defects in cytokinesis result in tetraploid, bi- nucleated cells that are genetically unstable and represent an important cause of tumorigenesis. The abnormal presence of he actin cytoskeleton plays a fundamental role in the initial lagging chromatin within the intercellular bridge (ICB) con- Tsteps of cytokinesis and is essential for cleavage furrow – necting the daughter cells is detected by an evolutionarily contraction (1 3). The cells are then connected by a thin cyto- conserved abscission checkpoint, which delays abscission and plasmic canal, the intercellular bridge (ICB), that is eventually cut stabilizes the ICB for hours, thereby preventing the formation in a complex process called abscission (4, 5). Abscission occurs on of binucleated cells and DNA damage. Here, we show that the one side of the midbody, the central part of the ICB (6, 7), and reductase MsrB2 enzymatically controls the polymerization of relies on endosomal sorting complex required for transport actin filaments in the ICB and prevents ICB instability specifi- (ESCRT)-III filaments that likely drive the final constriction (8–10). cally in the presence of lagging chromatin. This work thus re- The ESCRT machinery is first recruited at the midbody and later veals that actin reduction by MsrB2 is a key component of the concentrates at the abscission site itself, where the microtubules of abscission checkpoint. the ICB have been cleared by the microtubule-severing enzyme Spastin (11–13). Clearing actin filaments (F-actin) from the ICB is Author contributions: J.B., H.W., T.A., G.R.-L., and A.E. designed research; J.B., H.W., and equally important for successful abscission (14). Indeed, the T.A. performed research; J.B. and F.C. contributed new reagents/analytic tools; J.B., H.W., T.A., G.R.-L., and A.E. analyzed data; and J.B., H.W., T.A., G.R.-L., and A.E. wrote ESCRT-III assembles normally at the midbody but not at the ab- the paper. scission site when actin is not properly depolymerized (14, 15). Two The authors declare no competing interest. parallel pathways (Rab11/p50RhoGAP and Rab35/OCRL) con- This article is a PNAS Direct Submission. tribute to prevent excessive actin polymerization in the ICB (5, 16, Published under the PNAS license. 17). In addition, we recently found that the Rab35 GTPase recruits Data deposition: High quality versions of the figures are available on Zenodo (DOI: 10. the oxidase MICAL1 at the abscission site, in order to clear actin in 5281/zenodo.3635406). the ICB (18, 19). MICAL1 belongs to the MICAL monooxygenase 1To whom correspondence may be addressed. Email: [email protected]. – family (20 23), directly oxidizes Met44 and Met47 of F-actin into This article contains supporting information online at https://www.pnas.org/lookup/suppl/ methionine-R-sulfoxides, and triggers rapid depolymerization doi:10.1073/pnas.1911629117/-/DCSupplemental. of the filaments in vitro (18, 24–28). Thus, regulated oxidation First published February 6, 2020. www.pnas.org/cgi/doi/10.1073/pnas.1911629117 PNAS | February 25, 2020 | vol. 117 | no. 8 | 4169–4179 Downloaded by guest on September 24, 2021 abscission/NoCut checkpoint regulator [ANCHR] inactivation) we previously reported that delayed abscission after MICAL1 leads to ICB instability and eventually binucleated cells in the depletion was due to defective recruitment of ESCRT-III at the presence of chromatin bridges, and to an acceleration of ab- abscission site (18). This is evidenced by a decreased proportion scission in the absence of chromatin bridges (32, 38, 44, 50). of late ICBs with CHMP4B both at the midbody and abscission Interestingly, activation of the checkpoint was originally associ- site, concomitant with an increased proportion of late ICBs with ated with increased F-actin at or close to the ICB, and it was CHMP4B only at the midbody (Fig. 1E). We observed the op- speculated that it could help to maintain ICB stability for hours posite phenotype in cells depleted for MsrB2: a decreased pro- until chromatin bridges have been resolved (32). More recently, portion of late ICBs with CHMP4B only at the midbody and actin patches located at the entry points of the ICBs have been conversely an increased proportion of late ICBs with CHMP4B described to depend on the activation of the Src kinase (46), but both at the midbody and abscission site (Fig. 1E). Remarkably, whether F-actin is essential for the checkpoint has not been di- ESCRT-III localization was as in control cells after codepletion rectly tested. In addition, little is known about the mechanisms of MICAL1 and MsrB2 (Fig. 1E). We conclude that MsrB2 that directly control F-actin levels in the ICB region when the counteracts MICAL1 activity in controlling F-actin levels abscission checkpoint is activated. during late cytokinesis, ESCRT-III recruitment at the abscis- We hypothesized that oxidation-mediated clearance of F-actin sion site, and the timing of abscission. Our results also suggest by MICAL1 might be counteracted by actin reduction by methio- that MsrB2 depletion accelerates abscission by decreasing nine sulfoxide reductases (MsrBs) during cell division. MsrBs be- F-actin levels, which then favors the localization of ESCRT-III long to a family of enzymes found in all living organisms (51, 52), in at the abscission site. particular dSelR in Drosophila and its orthologs MsrB1-3 in hu- mans, that selectively reduce methionine-R-sulfoxide in vitro (25, MsrB2 Selectively Reduces Actin Monomers Whereas MICAL1 Only 28,53).Invivo,Drosophila dSelR counteracts dMical-mediated Oxidizes Actin Filaments In Vitro. Purified dSelR and MsrB1/B2 actin disassembly in bristle development, axon guidance, and are known to counteract MICALs on F-actin polymerization muscle organization
Load more

Recommended publications
  • Increased Frequency of Micronuclei in Binucleated Lymphocytes Among Occupationally Pesticide-Exposed Populations: a Meta- Analysis
    DOI:http://dx.doi.org/10.7314/APJCP.2014.15.16.6955 Micronuclei in Binucleated Lymphocytes and Occupational Exposure to Pesticides RESEARCH ARTICLE Increased Frequency of Micronuclei in Binucleated Lymphocytes among Occupationally Pesticide-exposed Populations: A Meta- analysis Hai-Yan Yang1&, Ruo Feng2&, Jing Liu1, Hai-Yu Wang3, Ya-Dong Wang3* Abstract Background: The cytokinesis-block micronucleus (CBMN) assay is a standard cytogenetic tool employed to evaluate chromosomal damage subsequent to pesticide exposure. Objectives: To evaluate the pooled levels of total micronuclei (MN) and binucleated cells with micronuclei (MNC) in 1000 binucleated lymphocytes among population occupationally exposed to pesticides and further determine the more sensitive biomarker of CBMN. Materials and Methods: A meta-analysis on the pooled levels of MN and MNC in binucleated lymphocytes among occupationally pesticide-exposed populations was conducted using STATA 10.0 software and Review Manager 5.0.24 in this study. Results: We found significant differences in frequencies of MN and MNC in 1000 binucleated lymphocytes between pesticide-exposed groups and controls, and the summary estimates of weighted mean difference were 6.82 [95% confidence interval (95% CI): 4.86-8.78] and 5.08 (95% CI: 2.93-7.23), respectively. However, when we conducted sensitivity analyses further, only the MN remained statistically different, but not the MNC, the summary estimates of weight mean difference were 2.86 (95% CI: 2.51-3.21) and 0.50 (95% CI: -0.16-1.17), respectively. We also observed pesticide-exposed subjects had significantly higher MN frequencies than controls among smokers and nonsmokers, male and female populations, and American, Asian and European countries in stratified analyses.Conclusions : The frequency of MN in peripheral blood lymphocytes might be a more sensitive indicator of early genetic effects than MNC using the CBMN assay for occupationally pesticide- exposed populations.
    [Show full text]
  • Tissue-Specific Control of Midbody Microtubule Stability by Citron Kinase Through Modulation of TUBB3 Phosphorylation
    Cell Death and Differentiation (2016) 23, 801–813 & 2016 Macmillan Publishers Limited All rights reserved 1350-9047/16 www.nature.com/cdd Tissue-specific control of midbody microtubule stability by Citron kinase through modulation of TUBB3 phosphorylation F Sgrò1, FT Bianchi1, M Falcone1, G Pallavicini1, M Gai1, AMA Chiotto1, GE Berto1,ETurco1, YJ Chang2, WB Huttner2 and F Di Cunto*,1,3 Cytokinesis, the physical separation of daughter cells at the end of cell cycle, is commonly considered a highly stereotyped phenomenon. However, in some specialized cells this process may involve specific molecular events that are still largely unknown. In mammals, loss of Citron-kinase (CIT-K) leads to massive cytokinesis failure and apoptosis only in neuronal progenitors and in male germ cells, resulting in severe microcephaly and testicular hypoplasia, but the reasons for this specificity are unknown. In this report we show that CIT-K modulates the stability of midbody microtubules and that the expression of tubulin β-III (TUBB3) is crucial for this phenotype. We observed that TUBB3 is expressed in proliferating CNS progenitors, with a pattern correlating with the susceptibility to CIT-K loss. More importantly, depletion of TUBB3 in CIT-K-dependent cells makes them resistant to CIT-K loss, whereas TUBB3 overexpression increases their sensitivity to CIT-Kknockdown. The loss of CIT-K leads to a strong decrease in the phosphorylation of S444 on TUBB3, a post-translational modification associated with microtubule stabilization. CIT-K may promote this event by interacting with TUBB3 and by recruiting at the midbody casein kinase-2α (CK2α) that has previously been reported to phosphorylate the S444 residue.
    [Show full text]
  • Cyclin B-Cdk Activity Stimulates Meiotic Rereplication in Budding Yeast
    Copyright 2004 by the Genetics Society of America DOI: 10.1534/genetics.104.029223 Cyclin B-Cdk Activity Stimulates Meiotic Rereplication in Budding Yeast Randy Strich,*,1 Michael J. Mallory,* Michal Jarnik* and Katrina F. Cooper† *Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111 and †Department of Biochemistry, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102 Manuscript received March 23, 2004 Accepted for publication April 30, 2004 ABSTRACT Haploidization of gametes during meiosis requires a single round of premeiotic DNA replication (meiS) followed by two successive nuclear divisions. This study demonstrates that ectopic activation of cyclin B/cyclin-dependent kinase in budding yeast recruits up to 30% of meiotic cells to execute one to three additional rounds of meiS. Rereplication occurs prior to the meiotic nuclear divisions, indicating that this process is different from the postmeiotic mitoses observed in other fungi. The cells with overreplicated DNA produced asci containing up to 20 spores that were viable and haploid and demonstrated Mendelian marker segregation. Genetic tests indicated that these cells executed the meiosis I reductional division and possessed a spindle checkpoint. Finally, interfering with normal synaptonemal complex formation or recombination increased the efficiency of rereplication. These studies indicate that the block to rereplica- tion is very different in meiotic and mitotic cells and suggest a negative role for the recombination machinery in allowing rereplication. Moreover, the production of haploids, regardless of the genome content, suggests that the cell counts replication cycles, not chromosomes, in determining the number of nuclear divisions to execute. EIOSIS is the process by which diploid organisms 2002; Whitmire et al.
    [Show full text]
  • Conservation of the B Mating-Type Gene Complex Among Bipolar and Tetrapolar Smut Fungi
    The Plant Cell, Vol. 5, 123-136, January 1993 O 1993 American Society of Plant Physiologists Conservation of the b Mating-Type Gene Complex among Bipolar and Tetrapolar Smut Fungi Guus Bakkerena and James W. Kronstadaibl‘ a Biotechnology Laboratory, University of British Columbia, Vancouver, British Columbia, Canada V6T 123 Departments of Microbiology and Plant Science, University of British Columbia, Vancouver, British Columbia, Canada V6T 123 In the phytopathogenic fungus Ustilago hordei, one locus with two alternate alleles, MAT.1 and MAT-2, controls mating and the establishment of the infectious dikaryon (bipolar mating). In contrast, for U. maydis, these functions are associated with two different gene complexes, called a and b (tetrapolar mating); the a complex has two alternate specificities, and the b gene complex is multiallelic. We have found homologs for the b gene complex in U. bordei and have cloned one from each mating type using sequences f” one bEast allele of U. maydis as a probe. Sequence analysis revealed two divergent open reading frames in each b complex, which we called bW (bWest) and bE (bEast) in analogy with the b gene complex of U. maydis. The predicted bW and bE gene products from the two different mating types showed .v75% identity when homologous polypeptides were compared. All of the characterized bW and bE gene products have variable amino-terminal regions, consenred carboxy-terminal regions, and similar homeodomain motifs. Sequence comparisons with the bW1 and bE1 genes of U. maydis showed conservation in organization and structure. Ransformation of the U. bordei b gene complex into a U.
    [Show full text]
  • Chromatin-Induced Spindle Assembly Plays an Important Role in Metaphase Congression of Silkworm Holocentric Chromosomes Hiroaki Mon
    University of Rhode Island DigitalCommons@URI Biological Sciences Faculty Publications Biological Sciences 2013 Chromatin-induced Spindle Assembly Plays an Important Role in Metaphase Congression of Silkworm Holocentric Chromosomes Hiroaki Mon Jae Man Lee See next page for additional authors Follow this and additional works at: https://digitalcommons.uri.edu/bio_facpubs The University of Rhode Island Faculty have made this article openly available. Please let us know how Open Access to this research benefits oy u. This is a pre-publication author manuscript of the final, published article. Terms of Use This article is made available under the terms and conditions applicable towards Open Access Policy Articles, as set forth in our Terms of Use. Citation/Publisher Attribution Hon, H., Lee J. M., Mita, K., Goldsmith, M. R., & Kusakabe, T. (2013). Chromatin-induced spindle assembly plays an important role in metaphase congression of silkworm holocentric chromosomes. Insect Biochemistry and Molecular Biology, 45, 1-11. Available at: http://dx.doi.org/10.1016/j.ibmb.2013.11.007 This Article is brought to you for free and open access by the Biological Sciences at DigitalCommons@URI. It has been accepted for inclusion in Biological Sciences Faculty Publications by an authorized administrator of DigitalCommons@URI. For more information, please contact [email protected]. Authors Hiroaki Mon, Jae Man Lee, Kazuei Mita, Marian R. Goldsmith, and Takahiro Kusakabe This article is available at DigitalCommons@URI: https://digitalcommons.uri.edu/bio_facpubs/27 1 Chromatin-induced spindle assembly plays an important role in 2 metaphase congression of silkworm holocentric chromosomes 3 4 Hiroaki Mona, Jae Man Leea, Kazuei Mitab, 5 Marian R.
    [Show full text]
  • Single-Cell Analysis of Ploidy and Centrosomes Underscores the Peculiarity of Normal Hepatocytes
    Università degli Studi di Milano Scuola di Dottorato in Medicina Molecolare Curriculum di Genomics, Proteomics e tecnologie correlate Ciclo XXV Anno Accademico 2011/2012 Settore disciplinare BIO10 Dottorando: Francesca FAGGIOLI Single-cell analysis of ploidy and centrosomes underscores the peculiarity of normal hepatocytes Direttore della Scuola: Ch.mo Prof. Mario CLERICI Tutore: Prof. Cristina BATTAGLIA Correlatore: Prof. Paolo Maria VEZZONI Albert Einstein College of Medicine, New York Istituto clinico Humanitas, Rozzano, Milano Alla mia famiglia “Only the ideas that we really live have any value” Hermann Hesse ABSTRACT STATE OF ART: The literature reports that, contrary to most other cell types, adult hepatocytes are polyploid cells with a DNA content of 4, 8 or even 16 haploid genomes. In fetal and early neonatal life, hepatocytes are mononucleated diploid cells that, quite abruptly, become binucleated and polyploid soon after weaning. The generation of tetraploid intermediates is not an uncommon event in the liver. These cells have the potential to generate aneuploid progeny in the subsequent cell division, because of the presence of four centrosomes. Normally in diploid cells, at the beginning of mitosis, a single centrosome duplicates and the mother and daughter organelles migrate to opposite cell poles, directing the formation of the spindle, to guarantee a balanced chromosomal segregation. Four centrosomes can cluster together, mimicking a bipolar spindle, or, as reported for tumoral cells, act as single entities that generate
    [Show full text]
  • Loss of E-Cadherin Provides Tolerance to Centrosome Amplification in Epithelial Cancer Cells
    JCB: Article Loss of E-cadherin provides tolerance to centrosome amplification in epithelial cancer cells Alexander D. Rhys,1 Pedro Monteiro,1* Christopher Smith,2* Malti Vaghela,3* Teresa Arnandis,1 Takuya Kato,4 Birgit Leitinger,5 Erik Sahai,4 Andrew McAinsh,2 Guillaume Charras,3 and Susana A. Godinho1 1Barts Cancer Institute–CRUK Centre, Queen Mary University of London, John Vane Science Centre, London, England, UK 2Centre for Mechanochemical Cell Biology, Division of Biomedical Science, Warwick Medical School, University of Warwick, Coventry, England, UK 3London Centre for Nanotechnology, University College London, London, England, UK 4Tumour Cell Biology Laboratory, Francis Crick Institute, London, England, UK 5Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London, England, UK Downloaded from http://rupress.org/jcb/article-pdf/217/1/195/1375641/jcb_201704102.pdf by guest on 02 October 2021 Centrosome amplification is a common feature of human tumors. To survive, cancer cells cluster extra centrosomes during mitosis, avoiding the detrimental effects of multipolar divisions. However, it is unclear whether clustering requires adaptation or is inherent to all cells. Here, we show that cells have varied abilities to cluster extra centrosomes. Epithelial cells are innately inefficient at clustering even in the presence of HSET/KIFC1, which is essential but not sufficient to promote clustering. The presence of E-cadherin decreases cortical contractility during mitosis through a signaling cas- cade leading to multipolar divisions, and its knockout promotes clustering and survival of cells with multiple centrosomes. Cortical contractility restricts centrosome movement at a minimal distance required for HSET/KIFC1 to exert its function, highlighting a biphasic model for centrosome clustering.
    [Show full text]
  • Centrosome Dynamics and Its Role in Inflammatory Response And
    biomolecules Review Centrosome Dynamics and Its Role in Inflammatory Response and Metastatic Process Massimo Pancione 1,*, Luigi Cerulo 1, Andrea Remo 2 , Guido Giordano 3 , Álvaro Gutierrez-Uzquiza 4,5, Paloma Bragado 4,5 and Almudena Porras 4,5 1 Department of Sciences and Technologies, University of Sannio, 82100 Benevento, Italy; [email protected] 2 Pathology Unit, Mater Salutis Hospital AULSS9, “Scaligera”, 37122 Verona, Italy; [email protected] 3 Department of Medical Oncology Unit, University of Foggia, 71122 Foggia, Italy; [email protected] 4 Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Complutense University Madrid, 28040 Madrid, Spain; [email protected] (Á.G.-U.); [email protected] (P.B.); [email protected] (A.P.) 5 Health Research Institute of the Hospital Clínico San Carlos (IdISSC), 28040 Madrid, Spain * Correspondence: [email protected]; Tel.: +39-0824305116 Abstract: Metastasis is a process by which cancer cells escape from the location of the primary tumor invading normal tissues at distant organs. Chromosomal instability (CIN) is a hallmark of human cancer, associated with metastasis and therapeutic resistance. The centrosome plays a major role in organizing the microtubule cytoskeleton in animal cells regulating cellular architecture and cell division. Loss of centrosome integrity activates the p38-p53-p21 pathway, which results in cell-cycle arrest or senescence and acts as a cell-cycle checkpoint pathway. Structural and numerical centrosome Citation: Pancione, M.; Cerulo, L.; abnormalities can lead to aneuploidy and CIN. New findings derived from studies on cancer and rare Remo, A.; Giordano, G.; Gutierrez- Uzquiza, Á.; Bragado, P.; Porras, A.
    [Show full text]
  • Nuclear Phenomena of Sexual Reproduction in Fungi
    NUCLEAR PHENOMENA OF SEXUAL REPRO- DUCTION IN FUNGI1 PROFESSOR R. A. HARPER -UNIVERSITY OP AWISCONSINT IhTthe light of recentresearches the old dogma that thme parasitic.mode of life tends to tlmedisappearance of sex- uality lhas practically disappeared at least so far as the fungi are concerned. Tlmeevidence is now generally ac- cepted that either a typical conjugation of normallydif- ferentiatedgametes and their nuclei or somimeform of sub- stitute for it is everywherepresemit. Ernst and Schmiidton tlmebasis of their studies on the root parasite Raqi7iesiahave also recentlyemphasized tlme fact that there is no evidence iii tihecase of seed plants that timeparasitic habit temidisto timedisappearance of .sexuality. Farmer and Digby have described a m-ost remarkable substitutefusion in an apoganmousfern and. a still miorestrikinog case of substitute cell and nuclear fusions in another apogam-iousferml has been recentlydis- covered in my own laboratory. It is proper under these conditions to examimimmeanew and most critically all cases of cell fusions with reference to their accompanying nuclear phenomena and possible significancein the life cycle in question. The study of sexuality in timefungi has also broughtto light some fundalameutalmoodifications of the process of' sexual fusion as found elsewhere which enlarge our con- ception of timenature and significanceof gamueticunions. It has also revealed most.curious and strikiingsubstitu- tions for sexual fusions. I shall review brieflythe most characteristicand significantof these variatiomisfrom the ordinary methodsof sexual reproduction. The fusion of 'A paper read by invitation before the Botanical Society of America, Boston, Decemnber30, 1909. 533 This content downloaded from 142.109.001.196 on February 18, 2018 20:56:27 PM All use subject to University of Chicago Press Terms and Conditions (http://www.journals.uchicago.edu/t-and-c).
    [Show full text]
  • Isolation of Cardiomyocytes Undergoing Mitosis with Complete Cytokinesis Hsiao-Yun Y
    bioRxiv preprint doi: https://doi.org/10.1101/549212; this version posted February 13, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Isolation of cardiomyocytes undergoing mitosis with complete cytokinesis Hsiao-yun Y. Milliron Ph.D1†, Matthew J. Weiland M.S.1†, Eric J. Kort M.D. M.S.1,2†, and Stefan Jovinge MD Ph.D1,3,4* †Equal contribution Short title: Isolation of cytokinetic cardiomyocytes by MB-FACS 1. DeVos Cardiovascular Research Program, Van Andel Institute and Spectrum Health Grand Rapids, MI 2. Department of Pediatrics & Human Development, College of Human Medicine, Michigan State University, East Lansing, MI 3. Fredrik Meijer Heart and Vascular Institute, Spectrum Health, Grand Rapids, MI 4. Cardiovascular Institute, Stanford University, Palo Alto, CA H.Y.M. and S.J. designed the study. H.Y.M. and M.J.W. performed the experiments. H.Y.M., M.J.W. and E.J.K. performed analysis. H.Y.M., M.J.W., E.J.K. and S.J. wrote the manuscript. *Correspondence: [email protected] Word count: 7988 Subject codes: Gene Expression and Regulation, Myocardial Regeneration, Myocardial biology, Cellular Reprogramming 1 bioRxiv preprint doi: https://doi.org/10.1101/549212; this version posted February 13, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Abstract Rationale-Adult human cardiomyocytes (CMs) do not complete cytokinesis despite passing through the S-phase of the cell cycle.
    [Show full text]
  • Research Article Establishment and Characterization of a Telomerase-Immortalized Sheep Trophoblast Cell Line
    Hindawi Publishing Corporation BioMed Research International Volume 2016, Article ID 5808575, 9 pages http://dx.doi.org/10.1155/2016/5808575 Research Article Establishment and Characterization of a Telomerase-Immortalized Sheep Trophoblast Cell Line Yufei Zhang,1 Jing Shi,1 and Shuying Liu1,2 1 College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot 010018, China 2Key Laboratory of Clinical Diagnosis and Treatment Technology in Animal Disease, Ministry of Agriculture, Hohhot 010018, China Correspondence should be addressed to Shuying Liu; liushuying [email protected] Received 12 September 2015; Revised 16 December 2015; Accepted 13 January 2016 Academic Editor: Louiza Belkacemi Copyright © 2016 Yufei Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The primary sheep trophoblast cells (STCs) have a finite lifespan in culture. This feature limits the scope for long-term in vitro studies with STCs. This study was an attempt to establish and characterize a telomerase-immortalized sheep trophoblast cell line. STCs were isolated and purified by using Percoll and specific immunoaffinity purification, respectively. The purified STCswere transfected with a plasmid carrying sequences of human telomerase reverse transcriptase (hTERT) to create immortalized sheep trophoblast cell line (hTERT-STCs). hTERT-STCs showed a stable expression of hTERT gene, serially passaged for a year, and showed active proliferation without signs of senescence. Cytokeratin 7 (CK-7), secreted human chorionic gonadotrophin subunit (CG-), placental lactogen (PL), and endogenous jaagsiekte sheep retrovirus (enJSRV) envelope genes were expressed in hTERT- STCs.
    [Show full text]
  • Single-Cell Analysis of Ploidy and Centrosomes Underscores the Peculiarity of Normal Hepatocytes
    Single-Cell Analysis of Ploidy and Centrosomes Underscores the Peculiarity of Normal Hepatocytes Francesca Faggioli1,2, Paolo Vezzoni1,2*, Cristina Montagna3,4 1 Milan Unit, Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Milan, Italy, 2 Medical Biotechnologies Unit, Istituto Clinico Humanitas, Rozzano, Milan, Italy, 3 Departments of Genetics, Albert Einstein College of Medicine, New York, New York, United States of America, 4 Pathology, Albert Einstein College of Medicine, New York, New York, United States of America Abstract Polyploidization is the most well recognized feature of the liver. Yet, a quantitative and behavioral analysis of centrosomes and DNA content in normal hepatocytes has been limited by the technical challenges of methods available. By using a novel approach employing FISH for chromosomes 18, X and Y we provide, for the first time, a detailed analysis of DNA copies during physiological development in the liver at single cell level. We demonstrate that aneuploidy and unbalanced DNA content in binucleated hepatocytes are common features in normal adult liver. Despite the common belief that hepatocytes contain 1, 2 or no more than 4 centrosomes, our double staining for centrosome associated proteins reveals extranumerary centrosomes in a high percentage of cells as early as 15 days of age. We show that in murine liver the period between 15 days and 1.5 months marks the transition from a prevalence of mononucleated cells to up to 75% of binucleated cells. Our data demonstrate that this timing correlates with a switch in centrosomes number. At 15 days the expected 1 or 2 centrosomes converge with several hepatocytes that contain 3 centrosomes; at 1.5 months the percentage of cells with 3 centrosomes decreases concomitantly with the increase of cells with more than 4 centrosomes.
    [Show full text]