The Second Subunit of DNA Polymerase Delta Is Required for Genomic Stability and Epigenetic Regulation1[OPEN]
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A Mutation in DNA Polymerase Α Rescues WEE1KO Sensitivity to HU
International Journal of Molecular Sciences Article A Mutation in DNA Polymerase α Rescues WEE1KO Sensitivity to HU Thomas Eekhout 1,2 , José Antonio Pedroza-Garcia 1,2 , Pooneh Kalhorzadeh 1,2, Geert De Jaeger 1,2 and Lieven De Veylder 1,2,* 1 Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium; [email protected] (T.E.); [email protected] (J.A.P.-G.); [email protected] (P.K.); [email protected] (G.D.J.) 2 Center for Plant Systems Biology, VIB, 9052 Gent, Belgium * Correspondence: [email protected] Abstract: During DNA replication, the WEE1 kinase is responsible for safeguarding genomic integrity by phosphorylating and thus inhibiting cyclin-dependent kinases (CDKs), which are the driving force of the cell cycle. Consequentially, wee1 mutant plants fail to respond properly to problems arising during DNA replication and are hypersensitive to replication stress. Here, we report the identification of the pola-2 mutant, mutated in the catalytic subunit of DNA polymerase α, as a suppressor mutant of wee1. The mutated protein appears to be less stable, causing a loss of interaction with its subunits and resulting in a prolonged S-phase. Keywords: replication stress; DNA damage; cell cycle checkpoint Citation: Eekhout, T.; Pedroza- 1. Introduction Garcia, J.A.; Kalhorzadeh, P.; De Jaeger, G.; De Veylder, L. A Mutation DNA replication is a highly complex process that ensures the chromosomes are in DNA Polymerase α Rescues correctly replicated to be passed onto the daughter cells during mitosis. Replication starts WEE1KO Sensitivity to HU. Int. -
Telomeres.Pdf
Telomeres Secondary article Elizabeth H Blackburn, University of California, San Francisco, California, USA Article Contents . Introduction Telomeres are specialized DNA–protein structures that occur at the ends of eukaryotic . The Replication Paradox chromosomes. A special ribonucleoprotein enzyme called telomerase is required for the . Structure of Telomeres synthesis and maintenance of telomeric DNA. Synthesis of Telomeric DNA by Telomerase . Functions of Telomeres Introduction . Telomere Homeostasis . Alternatives to Telomerase-generated Telomeric DNA Telomeres are the specialized chromosomal DNA–protein . Evolution of Telomeres and Telomerase structures that comprise the terminal regions of eukaryotic chromosomes. As discovered through studies of maize and somes. One critical part of this protective function is to fruitfly chromosomes in the 1930s, they are required to provide a means by which the linear chromosomal DNA protect and stabilize the genetic material carried by can be replicated completely, without the loss of terminal eukaryotic chromosomes. Telomeres are dynamic struc- DNA nucleotides from the 5’ end of each strand of this tures, with their terminal DNA being constantly built up DNA. This is necessary to prevent progressive loss of and degraded as dividing cells replicate their chromo- terminal DNA sequences in successive cycles of chromo- somes. One strand of the telomeric DNA is synthesized by somal replication. a specialized ribonucleoprotein reverse transcriptase called telomerase. Telomerase is required for both -
Emergence of DNA Polymerase E Antimutators That Escape Error-Induced Extinction in Yeast
INVESTIGATION Emergence of DNA Polymerase e Antimutators That Escape Error-Induced Extinction in Yeast Lindsey N. Williams, Alan J. Herr, and Bradley D. Preston1 Department of Pathology, University of Washington, Seattle, Washington 98195 ABSTRACT DNA polymerases (Pols) e and d perform the bulk of yeast leading- and lagging-strand DNA synthesis. Both Pols possess intrinsic proofreading exonucleases that edit errors during polymerization. Rare errors that elude proofreading are extended into duplex DNA and excised by the mismatch repair (MMR) system. Strains that lack Pol proofreading or MMR exhibit a 10- to 100-fold increase in spontaneous mutation rate (mutator phenotype), and inactivation of both Pol d proofreading (pol3-01) and MMR is lethal due to replication error-induced extinction (EEX). It is unclear whether a similar synthetic lethal relationship exists between defects in Pol e proofreading (pol2-4) and MMR. Using a plasmid-shuffling strategy in haploid Saccharomyces cerevisiae, we observed synthetic lethality of pol2-4 with alleles that completely abrogate MMR (msh2D, mlh1D, msh3D msh6D,orpms1D mlh3D) but not with partial MMR loss (msh3D, msh6D, pms1D,ormlh3D), indicating that high levels of unrepaired Pol e errors drive extinction. However, variants that escape this error-induced extinction (eex mutants) frequently emerged. Five percent of pol2-4 msh2D eex mutants encoded second-site changes in Pol e that reduced the pol2-4 mutator phenotype between 3- and 23-fold. The remaining eex alleles were extragenic to pol2-4. The locations of antimutator amino-acid changes in Pol e and their effects on mutation spectra suggest multiple mechanisms of mutator suppression. Our data indicate that unrepaired leading- and lagging-strand polymerase errors drive extinction within a few cell divisions and suggest that there are polymerase-specific pathways of mutator suppression. -
Regulates Cellular Telomerase Activity by Methylation of TERT Promoter
www.impactjournals.com/oncotarget/ Oncotarget, 2017, Vol. 8, (No. 5), pp: 7977-7988 Research Paper Tianshengyuan-1 (TSY-1) regulates cellular Telomerase activity by methylation of TERT promoter Weibo Yu1, Xiaotian Qin2, Yusheng Jin1, Yawei Li2, Chintda Santiskulvong3, Victor Vu1, Gang Zeng4,5, Zuofeng Zhang6, Michelle Chow1, Jianyu Rao1,5 1Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA 2Beijing Boyuantaihe Biological Technology Co., Ltd., Beijing, China 3Genomics Core, Cedars-Sinai Medical Center, Los Angeles, CA, USA 4Department of Urology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA 5Jonsson Comprehensive Cancer Center, University of California at Los Angeles, Los Angeles, CA, USA 6Department of Epidemiology, School of Public Health, University of California at Los Angeles, Los Angeles, CA, USA Correspondence to: Jianyu Rao, email: [email protected] Keywords: TSY-1, hematopoietic cells, Telomerase, TERT, methylation Received: September 08, 2016 Accepted: November 24, 2016 Published: December 15, 2016 ABSTRACT Telomere and Telomerase have recently been explored as anti-aging and anti- cancer drug targets with only limited success. Previously we showed that the Chinese herbal medicine Tianshengyuan-1 (TSY-1), an agent used to treat bone marrow deficiency, has a profound effect on stimulating Telomerase activity in hematopoietic cells. Here, the mechanism of TSY-1 on cellular Telomerase activity was further investigated using HL60, a promyelocytic leukemia cell line, normal peripheral blood mononuclear cells, and CD34+ hematopoietic stem cells derived from umbilical cord blood. TSY-1 increases Telomerase activity in normal peripheral blood mononuclear cells and CD34+ hematopoietic stem cells with innately low Telomerase activity but decreases Telomerase activity in HL60 cells with high intrinsic Telomerase activity, both in a dose-response manner. -
Mutations That Separate the Functions of the Proofreading Subunit of the Escherichia Coli Replicase
G3: Genes|Genomes|Genetics Early Online, published on April 15, 2015 as doi:10.1534/g3.115.017285 Mutations that separate the functions of the proofreading subunit of the Escherichia coli replicase Zakiya Whatley*,1 and Kenneth N Kreuzer*§ *University Program in Genetics & Genomics, Duke University, Durham, NC 27705 §Department of Biochemistry, Duke University Medical Center, Durham, NC 27710 1 © The Author(s) 2013. Published by the Genetics Society of America. Running title: E. coli dnaQ separation of function mutants Keywords: DNA polymerase, epsilon subunit, linker‐scanning mutagenesis, mutation rate, SOS response Corresponding author: Kenneth N Kreuzer, Department of Biochemistry, Box 3711, Nanaline Duke Building, Research Drive, Duke University Medical Center, Durham, NC 27710 Phone: 919 684 6466 FAX: 919 684 6525 Email: [email protected] 1 Present address: Department of Biology, 300 N Washington Street, McCreary Hall, Campus Box 392, Gettysburg College, Gettysburg, PA 17325 Phone: 717 337 6160 Fax: 7171 337 6157 Email: [email protected] 2 ABSTRACT The dnaQ gene of Escherichia coli encodes the ε subunit of DNA polymerase III, which provides the 3’ 5’ exonuclease proofreading activity of the replicative polymerase. Prior studies have shown that loss of ε leads to high mutation frequency, partially constitutive SOS, and poor growth. In addition, a previous study from our lab identified dnaQ knockout mutants in a screen for mutants specifically defective in the SOS response following quinolone (nalidixic acid) treatment. To explain these results, we propose a model whereby in addition to proofreading, ε plays a distinct role in replisome disassembly and/or processing of stalled replication forks. -
A New Class of Disordered Elements Controls DNA Replication Through
RESEARCH ARTICLE A new class of disordered elements controls DNA replication through initiator self-assembly Matthew W Parker1,2, Maren Bell2, Mustafa Mir2, Jonchee A Kao2, Xavier Darzacq2, Michael R Botchan2*, James M Berger1* 1Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, United States; 2Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States Abstract The initiation of DNA replication in metazoans occurs at thousands of chromosomal sites known as origins. At each origin, the Origin Recognition Complex (ORC), Cdc6, and Cdt1 co- assemble to load the Mcm2-7 replicative helicase onto chromatin. Current replication models envisage a linear arrangement of isolated origins functioning autonomously; the extent of inter- origin organization and communication is unknown. Here, we report that the replication initiation machinery of D. melanogaster unexpectedly undergoes liquid-liquid phase separation (LLPS) upon binding DNA in vitro. We find that ORC, Cdc6, and Cdt1 contain intrinsically disordered regions (IDRs) that drive LLPS and constitute a new class of phase separating elements. Initiator IDRs are shown to regulate multiple functions, including chromosome recruitment, initiator-specific co- assembly, and Mcm2-7 loading. These data help explain how CDK activity controls replication initiation and suggest that replication programs are subject to higher-order levels of inter-origin organization. DOI: https://doi.org/10.7554/eLife.48562.001 *For -
The Architecture of a Eukaryotic Replisome
The Architecture of a Eukaryotic Replisome Jingchuan Sun1,2, Yi Shi3, Roxana E. Georgescu3,4, Zuanning Yuan1,2, Brian T. Chait3, Huilin Li*1,2, Michael E. O’Donnell*3,4 1 Biosciences Department, Brookhaven National Laboratory, Upton, New York, USA 2 Department of Biochemistry & Cell Biology, Stony Brook University, Stony Brook, New York, USA. 3 The Rockefeller University, 1230 York Avenue, New York, New York, USA. 4 Howard Hughes Medical Institute *Correspondence and requests for materials should be addressed to M.O.D. ([email protected]) or H.L. ([email protected]) ABSTRACT At the eukaryotic DNA replication fork, it is widely believed that the Cdc45-Mcm2-7-GINS (CMG) helicase leads the way in front to unwind DNA, and that DNA polymerases (Pol) trail behind the helicase. Here we use single particle electron microscopy to directly image a replisome. Contrary to expectations, the leading strand Pol ε is positioned ahead of CMG helicase, while Ctf4 and the lagging strand Pol α-primase (Pol α) are behind the helicase. This unexpected architecture indicates that the leading strand DNA travels a long distance before reaching Pol ε, it first threads through the Mcm2-7 ring, then makes a U-turn at the bottom to reach Pol ε at the top of CMG. Our work reveals an unexpected configuration of the eukaryotic replisome, suggests possible reasons for this architecture, and provides a basis for further structural and biochemical replisome studies. INTRODUCTION DNA is replicated by a multi-protein machinery referred to as a replisome 1,2. Replisomes contain a helicase to unwind DNA, DNA polymerases that synthesize the leading and lagging strands, and a primase that makes short primed sites to initiate DNA synthesis on both strands. -
Replication Stress: an Achilles' Heel of Glioma Cancer Stem–Like Cells Meredith A
Published OnlineFirst November 29, 2018; DOI: 10.1158/0008-5472.CAN-18-2439 Cancer Review Research Replication Stress: An Achilles' Heel of Glioma Cancer Stem–like Cells Meredith A. Morgan1, and Christine E. Canman2 Abstract Glioblastoma (GBM) is a highly aggressive form of cancer that Carruthers and colleagues investigated DNA replication stress as is resistant to standard therapy with concurrent radiation and an underlying mechanism responsible for upregulation of the temozolomide, two agents that work by inducing DNA damage. DDR and hence the radiation resistance of glioma stem–like An underlying causeof this resistance may be a subpopulation of cells. Furthermore, the authors explore the efficacy of combined cancer stem–like cells that display a heightened DNA damage ataxia telangiectasia and Rad3-related kinase and PARP inhibi- response (DDR). Although this DDR represents an attractive tors as a strategy to leverage these mechanisms and overcome therapeutic target for overcoming the resistance of GBMs to radiation resistance. Cancer Res; 78(24); 6713–6. Ó2018 AACR. radiotherapy, until now, the cause of this DDR upregulation has See related article by Carruthers and colleagues, Cancer Res; not been understood. In a previous issue of Cancer Research, 78(17); 5060–71. The cancer stem cell theory states that a small subpopulation of of replication factories compared with non-GSC populations tumor cells possess unique self-renewal properties that are capa- (6). These observations pointed to elevated levels of RS as ble of seeding new tumors and are a source of regrowth following causative of DDR activation in untreated GSCs, a hypothesis therapy (1). Glioma stem–like cells (GSC) are defined as CD133- supported by the high levels of RS in glioblastoma (GBM; positive cells that can initiate new tumors in mice (2). -
Congenital Microcephaly
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Sussex Research Online American Journal of Medical Genetics Part C (Seminars in Medical Genetics) ARTICLE Congenital Microcephaly DIANA ALCANTARA AND MARK O'DRISCOLL* The underlying etiologies of genetic congenital microcephaly are complex and multifactorial. Recently, with the exponential growth in the identification and characterization of novel genetic causes of congenital microcephaly, there has been a consolidation and emergence of certain themes concerning underlying pathomechanisms. These include abnormal mitotic microtubule spindle structure, numerical and structural abnormalities of the centrosome, altered cilia function, impaired DNA repair, DNA Damage Response signaling and DNA replication, along with attenuated cell cycle checkpoint proficiency. Many of these processes are highly interconnected. Interestingly, a defect in a gene whose encoded protein has a canonical function in one of these processes can often have multiple impacts at the cellular level involving several of these pathways. Here, we overview the key pathomechanistic themes underlying profound congenital microcephaly, and emphasize their interconnected nature. © 2014 Wiley Periodicals, Inc. KEY WORDS: cell division; mitosis; DNA replication; cilia How to cite this article: Alcantara D, O'Driscoll M. 2014. Congenital microcephaly. Am J Med Genet Part C Semin Med Genet 9999:1–16. INTRODUCTION mid‐gestation although glial cell division formation of the various cortical layers. and consequent brain volume enlarge- Furthermore, differentiating and devel- Congenital microcephaly, an occipital‐ ment does continue after birth [Spalding oping neurons must migrate to their frontal circumference of equal to or less et al., 2005]. Impaired neurogenesis is defined locations to construct the com- than 2–3 standard deviations below the therefore most obviously reflected clini- plex architecture and laminar layered age‐related population mean, denotes cally as congenital microcephaly. -
Human Glucokinase Gene
Proc. Nati. Acad. Sci. USA Vol. 89, pp. 7698-7702, August 1992 Genetics Human glucokinase gene: Isolation, characterization, and identification of two missense mutations linked to early-onset non-insulin-dependent (type 2) diabetes mellitus (glucose/metabolism/phosphorylation/structure4unctlon/chromosome 7) M. STOFFEL*, PH. FROGUELt, J. TAKEDA*, H. ZOUALItt, N. VIONNET*, S. NISHI*§, I. T. WEBER¶, R. W. HARRISON¶, S. J. PILKISII, S. LESAGEtt, M. VAXILLAIREtt, G. VELHOtt, F. SUNtt, F. lIRSt, PH. PASSAt, D. COHENt, AND G. I. BELL*"** *Howard Hughes Medical Institute, and Departments of Biochemistry and Molecular Biology, and of Medicine, The University of Chicago, 5841 South Maryland Avenue, MC1028, Chicago, IL 60637; §Second Division of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka 431-32, Japan; IDepartment of Pharmacology, Jefferson Cancer Institute, Thomas Jefferson University, Philadelphia, PA 19107; IlDepartment of Physiology and Biophysics, State University of New York, Stony Brook, NY 11794; tCentre d'Etude du Polymorphisme Humain, 27 rue Juliette Dodu, and Service d'Endocrinologie, H6pital Saint-Louis, 75010 Paris, France; and tG6ndthon, 1 rue de l'Internationale, 91000 Evry, France Communicated by Jean Dausset, May 28, 1992 ABSTRACT DNA polymorphisms in the glucokinase gene by maintaining a gradient for glucose transport into these cells have recently been shown to be tightly linked to early-onset thereby regulating hepatic glucose disposal. In (3 cells, glu- non-insulin-dependent diabetes mellitus in "80% of French cokinase is believed to be part of the glucose-sensing mech- families with this form of diabetes. We previously identified a anism and to be involved in the regulation ofinsulin secretion. -
POLD3 Is Haploinsufficient for DNA Replication in Mice
POLD3 is haploinsufficient for DNA replication in mice Matilde Murga1, Emilio Lecona1, Irene Kamileri2, Marcos Díaz3, Natalia Lugli2, Sotirios K. Sotiriou2, Marta E. Anton1, Juan Méndez3, Thanos D. Halazonetis2 and Oscar Fernandez-Capetillo1,4 1 Genomic Instability Group, Spanish National Cancer Research Centre, Madrid, Spain. 2Department of Molecular Biology, University of Geneva, Geneva, Switzerland. 3 DNA Replication Group, Spanish National Cancer Research Centre, Madrid, Spain. 4Science for Life Laboratories, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden. Correspondence: O.F. ([email protected]) Contact: Oscar Fernandez-Capetillo Spanish National Cancer Research Centre (CNIO) Melchor Fernandez Almagro, 3 Madrid 28029, Spain Tel.: +34.91.732.8000 Ext: 3480 Fax: +34.91.732.8028 Email: [email protected] POLD3 deficient mice SUMMARY The Pold3 gene encodes a subunit of the Polδ DNA polymerase complex. Pold3 orthologues are not essential in Saccharomyces cerevisiae or chicken DT40 cells, but the Schizzosaccharomyces pombe orthologue is essential. POLD3 also has a specialized role in the repair of broken replication forks, suggesting that POLD3 activity could be particularly relevant for cancer cells enduring high levels of DNA replication stress. We report here that POLD3 is essential for mouse development and is also required for viability in adult animals. Strikingly, even Pold3+/- mice were born at sub-Mendelian ratios and, of those born, some presented hydrocephaly and had a reduced lifespan. In cells, POLD3 deficiency led to replication stress and cell death, which were aggravated by expression of activated oncogenes. Finally, we show that Pold3 deletion destabilizes all members of the Polδ complex, explaining its major role in DNA replication and the severe impact of its deficiency. -
Arthur Kornberg Discovered (The First) DNA Polymerase Four
Arthur Kornberg discovered (the first) DNA polymerase Using an “in vitro” system for DNA polymerase activity: 1. Grow E. coli 2. Break open cells 3. Prepare soluble extract 4. Fractionate extract to resolve different proteins from each other; repeat; repeat 5. Search for DNA polymerase activity using an biochemical assay: incorporate radioactive building blocks into DNA chains Four requirements of DNA-templated (DNA-dependent) DNA polymerases • single-stranded template • deoxyribonucleotides with 5’ triphosphate (dNTPs) • magnesium ions • annealed primer with 3’ OH Synthesis ONLY occurs in the 5’-3’ direction Fig 4-1 E. coli DNA polymerase I 5’-3’ polymerase activity Primer has a 3’-OH Incoming dNTP has a 5’ triphosphate Pyrophosphate (PP) is lost when dNMP adds to the chain E. coli DNA polymerase I: 3 separable enzyme activities in 3 protein domains 5’-3’ polymerase + 3’-5’ exonuclease = Klenow fragment N C 5’-3’ exonuclease Fig 4-3 E. coli DNA polymerase I 3’-5’ exonuclease Opposite polarity compared to polymerase: polymerase activity must stop to allow 3’-5’ exonuclease activity No dNTP can be re-made in reversed 3’-5’ direction: dNMP released by hydrolysis of phosphodiester backboneFig 4-4 Proof-reading (editing) of misincorporated 3’ dNMP by the 3’-5’ exonuclease Fidelity is accuracy of template-cognate dNTP selection. It depends on the polymerase active site structure and the balance of competing polymerase and exonuclease activities. A mismatch disfavors extension and favors the exonuclease.Fig 4-5 Superimposed structure of the Klenow fragment of DNA pol I with two different DNAs “Fingers” “Thumb” “Palm” red/orange helix: 3’ in red is elongating blue/cyan helix: 3’ in blue is getting edited Fig 4-6 E.