scholarly journals Using a Human Papillomavirus Model to Study DNA Replication and Repair of Wild Type and Damaged DNA Templates in Mammalian Cells

2020 ◽  
Vol 21 (20) ◽  
pp. 7564
Author(s):  
Dipon Das ◽  
Molly L. Bristol ◽  
Pietro Pichierri ◽  
Iain M. Morgan
Keyword(s):  
Dna Replication ◽  
Viral Genome ◽  
Mammalian Cells ◽  
Human Papillomaviruses ◽  
Lacz Gene ◽  
Dna Templates ◽  
Protein Protein Interaction ◽  
Dna Replication And Repair ◽  
Cellular Components ◽  
Damaged Dna

Human papillomaviruses have 8kbp DNA episomal genomes that replicate autonomously from host DNA. During initial infection, the virus increases its copy number to 20–50 copies per cell, causing torsional stress on the replicating DNA. This activates the DNA damage response (DDR) and HPV replicates its genome, at least in part, using homologous recombination. An active DDR is on throughout the HPV life cycle. Two viral proteins are required for replication of the viral genome; E2 binds to 12bp palindromic sequences around the A/T rich origin of replication and recruits the viral helicase E1 via a protein–protein interaction. E1 forms a di-hexameric complex that replicates the viral genome in association with host factors. Transient replication assays following transfection with E1–E2 expression plasmids, along with an origin containing plasmid, allow monitoring of E1-E2 replication activity. Incorporating a bacterial lacZ gene into the origin plasmid allows for the determination of replication fidelity. Here we describe how we exploited this system to investigate replication and repair in mammalian cells, including using damaged DNA templates. We propose that this system has the potential to enhance the understanding of cellular components involved in DNA replication and repair.

scholarly journals Response of Xenopus Cds1 in Cell-free Extracts to DNA Templates with Double-stranded Ends

2000 ◽  
Vol 11 (5) ◽  
pp. 1535-1546 ◽  
Author(s):  
Zijian Guo ◽  
William G. Dunphy
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Dna Molecules ◽  
Dna Templates ◽  
Cell Cycle Delay ◽  
Checkpoint Kinases ◽  
Double Stranded Dna ◽  
Egg Extracts ◽  
Dna Ends ◽  
Damaged Dna

Although homologues of the yeast checkpoint kinases Cds1 and Chk1 have been identified in various systems, the respective roles of these kinases in the responses to damaged and/or unreplicated DNA in vertebrates have not been delineated precisely. Likewise, it is largely unknown how damaged DNA and unreplicated DNA trigger the pathways that contain these effector kinases. We report that XenopusCds1 (Xcds1) is phosphorylated and activated by the presence of some simple DNA molecules with double-stranded ends in cell-freeXenopus egg extracts. Xcds1 is not affected by aphidicolin, an agent that induces DNA replication blocks. In contrast,Xenopus Chk1 (Xchk1) responds to DNA replication blocks but not to the presence of double-stranded DNA ends. Immunodepletion of Xcds1 (and/or Xchk1) from egg extracts did not attenuate the cell cycle delay induced by double-stranded DNA ends. These results imply that the cell cycle delay triggered by double-stranded DNA ends either does not involve Xcds1 or uses a factor(s) that can act redundantly with Xcds1.

scholarly journals Acetylation of E2 by P300 Mediates Topoisomerase Entry at the Papillomavirus Replicon

2019 ◽  
Vol 93 (7) ◽  
Author(s):  
Yanique Thomas ◽  
Elliot J. Androphy
Keyword(s):  
Dna Replication ◽  
Viral Genome ◽  
Adult Population ◽  
Specific Effect ◽  
The United States ◽  
Dna Helicase ◽  
Human Papillomaviruses ◽  
Host Cells ◽  
Viral Dna ◽  
Viral Dna Replication

ABSTRACTHuman papillomavirus (HPV) E2 proteins are integral for the transcription of viral genes and the replication and maintenance of viral genomes in host cells. E2 recruits the viral DNA helicase E1 to the origin. A lysine (K111), highly conserved among almost all papillomavirus (PV) E2 proteins, is a target for P300 (EP300) acetylation and is critical for viral DNA replication (E. J. Quinlan, S. P. Culleton, S. Y. Wu, C. M. Chiang, et al., J Virol 87:1497–1507, 2013, https://doi.org/10.1128/JVI.02771-12; Y. Thomas and E. J. Androphy, J Virol 92:e01912-17, 2018, https://doi.org/10.1128/JVI.01912-17). Since the viral genome exists as a covalently closed circle of double-stranded DNA, topoisomerase 1 (Topo1) is thought to be required for progression of the replication forks. Due to the specific effect of K111 mutations on DNA unwinding (Y. Thomas and E. J. Androphy, J Virol 92:e01912-17, 2018, https://doi.org/10.1128/JVI.01912-17), we demonstrate that the E2 protein targets Topo1 to the viral origin, and this depends on acetylation of K111. The effect was corroborated by functional replication assays, in which higher levels of P300, but not its homolog CBP, caused enhanced replication with wild-type E2 but not the acetylation-defective K111 arginine mutant. These data reveal a novel role for lysine acetylation during viral DNA replication by regulating topoisomerase recruitment to the replication origin.IMPORTANCEHuman papillomaviruses affect an estimated 75% of the sexually active adult population in the United States, with 5.5 million new cases emerging every year. More than 200 HPV genotypes have been identified; a subset of them are linked to the development of cancers from these epithelial infections. Specific antiviral medical treatments for infected individuals are not available. This project examines the mechanisms that control viral genome replication and may allow the development of novel therapeutics.

scholarly journals Werner helicase control of human papillomavirus 16 E1-E2 DNA replication is regulated by SIRT1 deacetylation

2018 ◽  
Author(s):  
Dipon Das ◽  
Molly L Bristol ◽  
Nathan W Smith ◽  
Xu Wang ◽  
Pietro Pichierri ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Life Cycle ◽  
Dna Replication ◽  
Dna Damage Response ◽  
Mammalian Cells ◽  
Human Papillomaviruses ◽  
Repair Protein ◽  
Damage Response ◽  
Dna Repair Protein

AbstractHuman papillomaviruses (HPV) are double stranded DNA viruses causative in a host of human diseases including several cancers. Following infection two viral proteins, E1 and E2, activate viral replication in association with cellular factors, and stimulate the DNA damage response (DDR) during the replication process. E1-E2 uses homologous replication (HR) to facilitate DNA replication, but an understanding of host factors involved in this process remains incomplete. Previously we demonstrated that the class III deacetylase SIRT1, which can regulate HR, is recruited to E1-E2 replicating DNA and regulates the level of replication. Here we demonstrate that SIRT1 promotes the fidelity of E1-E2 replication and that the absence of SIRT1 results in reduced recruitment of the DNA repair protein Werner helicase (WRN) to E1-E2 replicating DNA. CRISPR/Cas9 editing demonstrates that WRN, like SIRT1, regulates the quantity and fidelity of E1-E2 replication. This is the first report of WRN regulation of E1-E2 DNA replication, or a role for WRN in the HPV life cycle. In the absence of SIRT1 there is an increased acetylation and stability of WRN, but a reduced ability to interact with E1-E2 replicating DNA. We present a model in which E1-E2 replication turns on the DDR stimulating SIRT1 deacetylation of WRN. This deacetylation promotes WRN interaction with E1-E2 replicating DNA to control the quantity and fidelity of replication. As well as offering a crucial insight into HPV replication control, this system offers a unique model for investigating the link between SIRT1 and WRN in controlling replication in mammalian cells.ImportanceHPV16 is the major viral human carcinogen, responsible for between 3 and 4% of all cancers worldwide. Following infection this virus activates the DNA damage response (DDR) to promote its life cycle, and recruits DDR proteins to its replicating DNA in order to facilitate homologous recombination during replication. This promotes the production of viable viral progeny. Our understanding of how HPV16 replication interacts with the DDR remains incomplete. Here we demonstrate that the cellular deacetylase SIRT1, which is a part of the E1-E2 replication complex, regulates recruitment of the DNA repair protein WRN to the replicating DNA. We demonstrate that WRN regulates the level and fidelity of E1-E2 replication. Overall the results suggest a mechanism where SIRT1 deacetylation of WRN promotes its interaction with E1-E2 replicating DNA to control the levels and fidelity of that replication.

scholarly journals DNA polymerase ζ in DNA replication and repair

2019 ◽  
Vol 47 (16) ◽  
pp. 8348-8361 ◽  
Author(s):  
Sara K Martin ◽  
Richard D Wood
Keyword(s):  
Dna Replication ◽  
Dna Polymerase ◽  
Dna Sequences ◽  
Mammalian Cells ◽  
Translesion Synthesis ◽  
Dna Lesions ◽  
Replication Forks ◽  
Dna Replication And Repair ◽  
Radiation Induced ◽  
Break Induced Replication

Abstract Here, we survey the diverse functions of DNA polymerase ζ (pol ζ) in eukaryotes. In mammalian cells, REV3L (3130 residues) is the largest catalytic subunit of the DNA polymerases. The orthologous subunit in yeast is Rev3p. Pol ζ also includes REV7 subunits (encoded by Rev7 in yeast and MAD2L2 in mammalian cells) and two subunits shared with the replicative DNA polymerase, pol δ. Pol ζ is used in response to circumstances that stall DNA replication forks in both yeast and mammalian cells. The best-examined situation is translesion synthesis at sites of covalent DNA lesions such as UV radiation-induced photoproducts. We also highlight recent evidence that uncovers various roles of pol ζ that extend beyond translesion synthesis. For instance, pol ζ is also employed when the replisome operates sub-optimally or at difficult-to-replicate DNA sequences. Pol ζ also participates in repair by microhomology mediated break-induced replication. A rev3 deletion is tolerated in yeast but Rev3l disruption results in embryonic lethality in mice. Inactivation of mammalian Rev3l results in genomic instability and invokes cell death and senescence programs. Targeting of pol ζ function may be a useful strategy in cancer therapy, although chromosomal instability associated with pol ζ deficiency must be considered.

scholarly journals Histone H3 Lysine 4 Methylation Marks Postreplicative Human Cytomegalovirus Chromatin

2012 ◽  
Vol 86 (18) ◽  
pp. 9817-9827 ◽  
Author(s):  
Alexandra Nitzsche ◽  
Charlotte Steinhäußer ◽  
Katrin Mücke ◽  
Christina Paulus ◽  
Michael Nevels
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Histone Modification ◽  
Dna Polymerase ◽  
Human Cytomegalovirus ◽  
Viral Genome ◽  
Histone H3 ◽  
Viral Dna ◽  
The Impact ◽  
Preferential Incorporation

In the nuclei of permissive cells, human cytomegalovirus genomes form nucleosomal structures initially resembling heterochromatin but gradually switching to a euchromatin-like state. This switch is characterized by a decrease in histone H3 K9 methylation and a marked increase in H3 tail acetylation and H3 K4 methylation across the viral genome. We used ganciclovir and a mutant virus encoding a reversibly destabilized DNA polymerase to examine the impact of DNA replication on histone modification dynamics at the viral chromatin. The changes in H3 tail acetylation and H3 K9 methylation proceeded in a DNA replication-independent fashion. In contrast, the increase in H3 K4 methylation proved to depend widely on viral DNA synthesis. Consistently, labeling of nascent DNA using “click chemistry” revealed preferential incorporation of methylated H3 K4 into viral (but not cellular) chromatin during or following DNA replication. This study demonstrates largely selective epigenetic tagging of postreplicative human cytomegalovirus chromatin.

Sign in / Sign up

Export Citation Format

Share Document