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break-induced replication

Fani-Marlen Roumelioti, Sotirios K Sotiriou, Vasiliki Katsini, Maria Chiourea, Thanos D Halazonetis, Sarantis Gagos
Human malignancies overcome replicative senescence either by activating the reverse-transcriptase telomerase or by utilizing a homologous recombination-based mechanism, referred to as alternative lengthening of telomeres (ALT). In budding yeast, ALT exhibits features of break-induced replication (BIR), a repair pathway for one-ended DNA double-strand breaks (DSBs) that requires the non-essential subunit Pol32 of DNA polymerase delta and leads to conservative DNA replication. Here, we examined whether ALT in human cancers also exhibits features of BIR A telomeric fluorescence in situ hybridization protocol involving three consecutive staining steps revealed the presence of conservatively replicated telomeric DNA in telomerase-negative cancer cells...
October 19, 2016: EMBO Reports
Robert L Dilley, Priyanka Verma, Nam Woo Cho, Harrison D Winters, Anne R Wondisford, Roger A Greenberg
Homology-directed DNA repair is essential for genome maintenance through templated DNA synthesis. Alternative lengthening of telomeres (ALT) necessitates homology-directed DNA repair to maintain telomeres in about 10-15% of human cancers. How DNA damage induces assembly and execution of a DNA replication complex (break-induced replisome) at telomeres or elsewhere in the mammalian genome is poorly understood. Here we define break-induced telomere synthesis and demonstrate that it utilizes a specialized replisome, which underlies ALT telomere maintenance...
October 19, 2016: Nature
Robin van Schendel, Jane van Heteren, Richard Welten, Marcel Tijsterman
For more than half a century, genotoxic agents have been used to induce mutations in the genome of model organisms to establish genotype-phenotype relationships. While inaccurate replication across damaged bases can explain the formation of single nucleotide variants, it remained unknown how DNA damage induces more severe genomic alterations. Here, we demonstrate for two of the most widely used mutagens, i.e. ethyl methanesulfonate (EMS) and photo-activated trimethylpsoralen (UV/TMP), that deletion mutagenesis is the result of polymerase Theta (POLQ)-mediated end joining (TMEJ) of double strand breaks (DSBs)...
October 2016: PLoS Genetics
Zhoushuai Qin, Zhiqiang Bai, Ying Sun, Xiaohong Niu, Wei Xiao
In response to replication-blocking lesions, proliferating cell nuclear antigen (PCNA) can be sequentially ubiquitinated at the K164 residue leading to two modes of DNA-damage tolerance, namely translesion DNA synthesis (TLS) and error-free lesion bypass. Ectopic expression of PCNA fused with ubiquitin (Ub) lacking the two C-terminal Gly residues resembles PCNA monoubiquitination-mediated TLS. However, if the fused Ub contains C-terminal Gly residues, it is further polyubiquitinated and inhibits cell proliferation...
October 18, 2016: Cell Cycle
Grasiella Angelina Andriani, Vinnycius Pereira Almeida, Francesca Faggioli, Maurizio Mauro, Wanxia Li Tsai, Laura Santambrogio, Alexander Maslov, Massimo Gadina, Judith Campisi, Jan Vijg, Cristina Montagna
Age-related accumulation of ploidy changes is associated with decreased expression of genes controlling chromosome segregation and cohesin functions. To determine the consequences of whole chromosome instability (W-CIN) we down-regulated the spindle assembly checkpoint component BUB1 and the mitotic cohesin SMC1A, and used four-color-interphase-FISH coupled with BrdU incorporation and analyses of senescence features to reveal the fate of W-CIN cells. We observed significant correlations between levels of not-diploid cells and senescence-associated features (SAFs)...
October 12, 2016: Scientific Reports
Adeline Feri, Raphaël Loll-Krippleber, Pierre-Henri Commere, Corinne Maufrais, Natacha Sertour, Katja Schwartz, Gavin Sherlock, Marie-Elisabeth Bougnoux, Christophe d'Enfert, Mélanie Legrand
: The diploid genome of the yeast Candida albicans is highly plastic, exhibiting frequent loss-of-heterozygosity (LOH) events. To provide a deeper understanding of the mechanisms leading to LOH, we investigated the repair of a unique DNA double-strand break (DSB) in the laboratory C. albicans SC5314 strain using the I-SceI meganuclease. Upon I-SceI induction, we detected a strong increase in the frequency of LOH events at an I-SceI target locus positioned on chromosome 4 (Chr4), including events spreading from this locus to the proximal telomere...
October 11, 2016: MBio
Amine Namouchi, Marta Gómez-Muñoz, Stephan A Frye, Line Victoria Moen, Torbjørn Rognes, Tone Tønjum, Seetha V Balasingham
BACKGROUND: As an intracellular human pathogen, Mycobacterium tuberculosis (Mtb) is facing multiple stressful stimuli inside the macrophage and the granuloma. Understanding Mtb responses to stress is essential to identify new virulence factors and pathways that play a role in the survival of the tubercle bacillus. The main goal of this study was to map the regulatory networks of differentially expressed (DE) transcripts in Mtb upon various forms of genotoxic stress. We exposed Mtb cells to oxidative (H2O2 or paraquat), nitrosative (DETA/NO), or alkylation (MNNG) stress or mitomycin C, inducing double-strand breaks in the DNA...
October 10, 2016: BMC Genomics
Young Me Yoon, Kelsie J Storm, Ashley N Kamimae-Lanning, Natalya A Goloviznina, Peter Kurre
Our mechanistic understanding of Fanconi anemia (FA) pathway function in hematopoietic stem and progenitor cells (HSPCs) owes much to their role in experimentally induced DNA crosslink lesion repair. In bone marrow HSPCs, unresolved stress confers p53-dependent apoptosis and progressive cell attrition. The role of FA proteins during hematopoietic development, in the face of physiological replicative demand, remains elusive. Here, we reveal a fetal HSPC pool in Fancd2(-/-) mice with compromised clonogenicity and repopulation...
October 6, 2016: Stem Cell Reports
Thomas Altmann, Andrew R Gennery
DNA ligase IV deficiency is a rare primary immunodeficiency, LIG4 syndrome, often associated with other systemic features. DNA ligase IV is part of the non-homologous end joining mechanism, required to repair DNA double stranded breaks. Ubiquitously expressed, it is required to prevent mutagenesis and apoptosis, which can result from DNA double strand breakage caused by intracellular events such as DNA replication and meiosis or extracellular events including damage by reactive oxygen species and ionising radiation...
October 7, 2016: Orphanet Journal of Rare Diseases
Aimee Jaramillo-Lambert, Amy S Fabritius, Tyler J Hansen, Harold E Smith, Andy Golden
Topoisomerase II alleviates DNA entanglements that are generated during mitotic DNA replication, transcription, and sister chromatid separation. In contrast to mitosis, meiosis has two rounds of chromosome segregation following one round of DNA replication. In meiosis II, sister chromatids segregate from each other similar to mitosis. Meiosis I, on the other hand, segregates homologs, which requires pairing, synapsis, and recombination. The exact role that topoisomerase II plays during meiosis is unknown. In a screen re-examining Caenorhabditis elegant legacy mutants isolated thirty years ago, we identified a novel allele of the gene encoding topoisomerase II, top-2(it7) In this study, we demonstrate that top-2(it7) males produce dead embryos, even when fertilizing wild-type oocytes...
October 5, 2016: Genetics
Atsushi T Onaka, Naoko Toyofuku, Takahiro Inoue, Akiko K Okita, Minami Sagawa, Jie Su, Takeshi Shitanda, Rei Matsuyama, Faria Zafar, Tatsuro S Takahashi, Hisao Masukata, Takuro Nakagawa
Centromeres consist of DNA repeats in many eukaryotes. Non-allelic homologous recombination (HR) between them can result in gross chromosomal rearrangements (GCRs). In fission yeast, Rad51 suppresses isochromosome formation that occurs between inverted repeats in the centromere. However, how the HR enzyme prevents homology-mediated GCRs remains unclear. Here, we provide evidence that Rad51 with the aid of the Swi/Snf-type motor protein Rad54 promotes non-crossover recombination between centromere repeats to prevent isochromosome formation...
October 3, 2016: Nucleic Acids Research
Andrew M Cobb, Thomas V Murray, Derek T Warren, Yiwen Liu, Catherine M Shanahan
The accumulation of prelamin A is linked to disruption of cellular homeostasis, tissue degeneration and ageing. Its expression is implicated in compromised genome stability and increased levels of DNA damage, but to date there is no complete explanation for how prelamin A exerts its toxic effects. As the nuclear lamina is important for DNA replication we wanted to investigate the relationship between prelamin A expression and DNA replication fork stability. In this study we report that the expression of prelamin A in U2OS cells induced both mono-ubiquitination of proliferating cell nuclear antigen (PCNA) and subsequent induction of Pol η, two hallmarks of DNA replication fork stalling...
September 27, 2016: Nucleus
Xiaoyan Li, Runzhou Ni
There are over 350 million chronic carriers of hepatitis B virus (HBV) in the world, of whom about a third eventually develop severe HBV-related complications. HBV contributes to liver cirrhosis and hepatocellular carcinoma development. Remarkable progress has been made in selective inhibition of HBV replication by nucleoside analogs. However, how to generate protective antibody of HBsAb in HBV-infected patients after HBV-DNA becomes negative still remains a challenge for scientists. In this study, we show that OmpC-HBsAg 'a' epitope chimeric protein vaccine can break HBV tolerance and induce protective immunity in HBV transgenic mice based on mimicking T cell-independent antigen to bypass T cells from the adaptive immune system...
September 23, 2016: Viral Immunology
Elena Yushkova, Vladimir Zainullin
PURPOSE: To analyze the role of mus-genes repair in system activation P-elements in Drosophila melanogaster induced by a chronic exposure to low doses. MATERIALS AND METHODS: The materials were dysgenic individuals of Drosophila melanogaster with mutations in repair genes (mus101, mus205, mus304, mus308, mus309) and simultaneous transposition of mobile P-elements. The animals were exposed to a chronic irradiation in low doses (0.42 mGy/h). The reaction of animals was analyzed by the DNA damage rate in somatic cells ('Comet assay'), level of dominant lethal mutations, fecundity, and survival rate...
September 2016: International Journal of Radiation Biology
Isabel Morgado-Palacin, Amanda Day, Matilde Murga, Vanesa Lafarga, Marta Elena Anton, Anthony Tubbs, Hua-Tang Chen, Aysegul Ergan, Rhonda Anderson, Avinash Bhandoola, Kurt G Pike, Bernard Barlaam, Elaine Cadogan, Xi Wang, Andrew J Pierce, Chad Hubbard, Scott A Armstrong, André Nussenzweig, Oscar Fernandez-Capetillo
Among the various subtypes of acute myeloid leukemia (AML), those with chromosomal rearrangements of the MLL oncogene (AML-MLL) have a poor prognosis. AML-MLL tumor cells are resistant to current genotoxic therapies because of an attenuated response by p53, a protein that induces cell cycle arrest and apoptosis in response to DNA damage. In addition to chemicals that damage DNA, efforts have focused on targeting DNA repair enzymes as a general chemotherapeutic approach to cancer treatment. Here, we found that inhibition of the kinase ATR, which is the primary sensor of DNA replication stress, induced chromosomal breakage and death of mouse AML(MLL) cells (with an MLL-ENL fusion and a constitutively active N-RAS independently of p53...
September 13, 2016: Science Signaling
Yasuto Yoneshima, Nona Abolhassani, Teruaki Iyama, Kunihiko Sakumi, Naoko Shiomi, Masahiko Mori, Tadahiro Shiomi, Tetsuo Noda, Daisuke Tsuchimoto, Yusaku Nakabeppu
Deoxyinosine (dI) occurs in DNA either by oxidative deamination of a previously incorporated deoxyadenosine residue or by misincorporation of deoxyinosine triphosphate (dITP) from the nucleotide pool during replication. To exclude dITP from the pool, mammals possess specific hydrolysing enzymes, such as inosine triphosphatase (ITPA). Previous studies have shown that deficiency in ITPA results in cell growth suppression and DNA instability. To explore the mechanisms of these phenotypes, we analysed ITPA-deficient human and mouse cells...
2016: Scientific Reports
Maximilian Mimmler, Simon Peter, Alexander Kraus, Svenja Stroh, Teodora Nikolova, Nina Seiwert, Solveig Hasselwander, Carina Neitzel, Jessica Haub, Bernhard H Monien, Petra Nicken, Pablo Steinberg, Jerry W Shay, Bernd Kaina, Jörg Fahrer
PhIP is an abundant heterocyclic aromatic amine (HCA) and important dietary carcinogen. Following metabolic activation, PhIP causes bulky DNA lesions at the C8-position of guanine. Although C8-PhIP-dG adducts are mutagenic, their interference with the DNA replication machinery and the elicited DNA damage response (DDR) have not yet been studied. Here, we analyzed PhIP-triggered replicative stress and elucidated the role of the apical DDR kinases ATR, ATM and DNA-PKcs in the cellular defense response. First, we demonstrate that PhIP induced C8-PhIP-dG adducts and DNA strand breaks...
September 5, 2016: Nucleic Acids Research
Sachini U Siriwardena, Kang Chen, Ashok S Bhagwat
The AID/APOBEC family enzymes convert cytosines in single-stranded DNA to uracils, causing base substitutions and strand breaks. They are induced by cytokines produced during the body's inflammatory response to infections, and they help combat infections through diverse mechanisms. AID is essential for the maturation of antibodies and causes mutations and deletions in antibody genes through somatic hypermutation (SHM) and class-switch recombination (CSR) processes. One member of the APOBEC family, APOBEC1, edits mRNA for a protein involved in lipid transport...
September 1, 2016: Chemical Reviews
Julie Nonnekens, Melissa van Kranenburg, Cecile E M T Beerens, Mustafa Suker, Michael Doukas, Casper H J van Eijck, Marion de Jong, Dik C van Gent
Metastases expressing tumor-specific receptors can be targeted and treated by binding of radiolabeled peptides (peptide receptor radionuclide therapy or PRRT). For example, patients with metastasized somatostatin receptor-positive neuroendocrine tumors (NETs) can be treated with radiolabeled somatostatin analogues, resulting in strongly increased progression-free survival and quality of life. There is nevertheless still room for improvement, as very few patients can be cured at this stage of disease. We aimed to specifically sensitize replicating tumor cells without further damage to healthy tissues...
2016: Theranostics
Arlene L Oei, Lianne E M Vriend, Caspar M van Leeuwen, Hans M Rodermond, Rosemarie Ten Cate, Anneke M Westermann, Lukas J A Stalpers, Johannes Crezee, Roland Kanaar, H Petra Kok, Przemek M Krawczyk, Nicolaas A P Franken
Cis-diamminedichloroplatinum(II) (cisplatin, cDDP) is an effective chemotherapeutic agent that induces DNA double strand breaks (DSBs), primarily in replicating cells. Generally, such DSBs can be repaired by the classical or backup non-homologous end joining (c-NHEJ/b-NHEJ) or homologous recombination (HR). Therefore, inhibiting these pathways in cancer cells should enhance the efficiency of cDDP treatments. Indeed, inhibition of HR by hyperthermia (HT) sensitizes cancer cells to cDDP and in the Netherlands this combination is a standard treatment option for recurrent cervical cancer after previous radiotherapy...
August 19, 2016: Oncotarget
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