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Double strand break

Bingjie Shi, Juan Li, Xuanling Shi, Wenxu Jia, Yi Wen, Xiongbing Hu, Fengfeng Zhuang, Jianzhong Xi, Linqi Zhang
Transcription activator-like effector nuclease (TALEN) represents a valuable tool for genomic engineering due to its single-nucleotide precision, high nuclease activity and low cytotoxicity. We report here systematic design and characterization of twenty eight novel TALENs targeting multiple regions of CCR5 gene (CCR5-TALEN) which encodes the co-receptor critical for entry of human immunodeficiency virus type I (HIV-1). By systemic characterization of these CCR5-TALENs, we have identified one (CCR5-TALEN-515) with higher nuclease activity, specificity and lower cytotoxicity compared to zinc-finger nuclease (CCR5-ZFN) currently undergoing clinical trials...
October 3, 2016: Journal of Acquired Immune Deficiency Syndromes: JAIDS
Manabu Koike, Yasutomo Yutoku, Aki Koike
Understanding the molecular mechanisms of DNA double-strand break (DSB) repair processes, especially nonhomologous DNA-end joining (NHEJ), is critical for developing next-generation radiotherapies and chemotherapeutics for human and animal cancers. The localization, protein-protein interactions and post-translational modifications of core NHEJ factors, such as human Ku70 and Ku80, might play critical roles in controlling NHEJ activity. XRCC4-like factor (XLF) is a core NHEJ factor and plays a key role in the Ku-dependent NHEJ repair process in human cells...
October 14, 2016: Journal of Veterinary Medical Science
Julian Lange, Shintaro Yamada, Sam E Tischfield, Jing Pan, Seoyoung Kim, Xuan Zhu, Nicholas D Socci, Maria Jasin, Scott Keeney
Heritability and genome stability are shaped by meiotic recombination, which is initiated via hundreds of DNA double-strand breaks (DSBs). The distribution of DSBs throughout the genome is not random, but mechanisms molding this landscape remain poorly understood. Here, we exploit genome-wide maps of mouse DSBs at unprecedented nucleotide resolution to uncover previously invisible spatial features of recombination. At fine scale, we reveal a stereotyped hotspot structure-DSBs occur within narrow zones between methylated nucleosomes-and identify relationships between SPO11, chromatin, and the histone methyltransferase PRDM9...
October 12, 2016: Cell
Nadezhda V Petrova, Artem V Luzhin, Ekaterina O Serebrovskaya, Alina P Ryumina, Artem K Velichko, Sergey V Razin, Omar L Kantidze
Cellular senescence, a form of cell cycle arrest, is one of the cellular responses to different types of exogenous and endogenous damage. The senescence phenotype can be induced in vitro by oncogene overexpression and/or DNA damage. Recently, we have reported a novel mechanism of cellular senescence induction by mild genotoxic stress. Specifically, we have shown that the formation of a small number of DNA lesions in normal and cancer cells during S phase leads to cellular senescence-like arrest within the same cell cycle...
October 14, 2016: Aging
Yinyin Li, Yi Shen, Philipp Hohensinner, Jihang Ju, Zhenke Wen, Stuart B Goodman, Hui Zhang, Jörg J Goronzy, Cornelia M Weyand
Immune aging manifests with a combination of failing adaptive immunity and insufficiently restrained inflammation. In patients with rheumatoid arthritis (RA), T cell aging occurs prematurely, but the mechanisms involved and their contribution to tissue-destructive inflammation remain unclear. We found that RA CD4(+) T cells showed signs of aging during their primary immune responses and differentiated into tissue-invasive, proinflammatory effector cells. RA T cells had low expression of the double-strand-break repair nuclease MRE11A, leading to telomeric damage, juxtacentromeric heterochromatin unraveling, and senescence marker upregulation...
October 10, 2016: Immunity
Jiawei Guan, Qian Zhao, Weifeng Mao
PTEN is a tumor suppressor gene characterized as a phosphatase that antagonizes the phosphatidylinositol 3-kinase signaling pathway in the cytoplasm. Nuclear PTEN plays roles in chromosomal stability, in which the double-strand breaks (DSB) repair mediated by homologous recombination (HR) and non-homologous end joining (NHEJ) is critical. Herein, the role of nuclear PTEN in DSB repair and the underlying molecular mechanism was investigated in this study. Using human breast cancer BT549 and MDA-MB-231 cell lines, we reveal a specific feature of PTEN that controls poly(ADP-ribosyl)ation of Ku70 and interferes with binding of Ku70 at DSB...
October 11, 2016: Biochimica et Biophysica Acta
Mae L Woods, Chris P Barnes
DNA double-strand breaks are lesions that form during metabolism, DNA replication and exposure to mutagens. When a double-strand break occurs one of a number of repair mechanisms is recruited, all of which have differing propensities for mutational events. Despite DNA repair being of crucial importance, the relative contribution of these mechanisms and their regulatory interactions remain to be fully elucidated. Understanding these mutational processes will have a profound impact on our knowledge of genomic instability, with implications across health, disease and evolution...
October 2016: PLoS Computational Biology
Lili Ni, Hongchang Xie, Li Tan
The transcription factor FOXJ3 (Forkhead box J3) is highly expressed in spermatogonia and meiotic spermatocytes within mouse testes. Here, we addressed how FOXJ3 might participate in spermatogenesis using two conditional knockout mouse models in which the Foxj3 was deleted from either spermatogonia or meiotic spermatocytes. Both models exhibited complete male sterility, but distinct etiologies: Deleting FOXJ3 from spermatogonia using Foxj3(flox/flox) , Mvh-Cre mice caused Sertoli-cell-only syndrome in males...
October 14, 2016: Molecular Reproduction and Development
Wynand Paul Roos, Andrea Krumm
Histone/protein deacetylases play multiple roles in regulating gene expression and protein activation and stability. Their deregulation during cancer initiation and progression cause resistance to therapy. Here, we review the role of histone deacetylases (HDACs) and the NAD(+) dependent sirtuins (SIRTs) in the DNA damage response (DDR). These lysine deacetylases contribute to DNA repair by base excision repair (BER), nucleotide excision repair (NER), mismatch repair (MMR), non-homologous end joining (NHEJ), homologous recombination (HR) and interstrand crosslink (ICL) repair...
October 13, 2016: Nucleic Acids Research
Aline Koch, Dagmar Biedenkopf, Alexandra Furch, Lennart Weber, Oliver Rossbach, Eltayb Abdellatef, Lukas Linicus, Jan Johannsmeier, Lukas Jelonek, Alexander Goesmann, Vinitha Cardoza, John McMillan, Tobias Mentzel, Karl-Heinz Kogel
Meeting the increasing food and energy demands of a growing population will require the development of ground-breaking strategies that promote sustainable plant production. Host-induced gene silencing has shown great potential for controlling pest and diseases in crop plants. However, while delivery of inhibitory noncoding double-stranded (ds)RNA by transgenic expression is a promising concept, it requires the generation of transgenic crop plants which may cause substantial delay for application strategies depending on the transformability and genetic stability of the crop plant species...
October 2016: PLoS Pathogens
Evandro Fei Fang, Henok Kassahun, Deborah L Croteau, Morten Scheibye-Knudsen, Krisztina Marosi, Huiming Lu, Raghavendra A Shamanna, Sumana Kalyanasundaram, Ravi Chand Bollineni, Mark A Wilson, Wendy B Iser, Bradley N Wollman, Marya Morevati, Jun Li, Jesse S Kerr, Qiping Lu, Tyler B Waltz, Jane Tian, David A Sinclair, Mark P Mattson, Hilde Nilsen, Vilhelm A Bohr
Ataxia telangiectasia (A-T) is a rare autosomal recessive disease characterized by progressive neurodegeneration and cerebellar ataxia. A-T is causally linked to defects in ATM, a master regulator of the response to and repair of DNA double-strand breaks. The molecular basis of cerebellar atrophy and neurodegeneration in A-T patients is unclear. Here we report and examine the significance of increased PARylation, low NAD(+), and mitochondrial dysfunction in ATM-deficient neurons, mice, and worms. Treatments that replenish intracellular NAD(+) reduce the severity of A-T neuropathology, normalize neuromuscular function, delay memory loss, and extend lifespan in both animal models...
October 11, 2016: Cell Metabolism
James E Haber
Double-strand breaks (DSBs) pose a severe challenge to genome integrity; consequently, cells have developed efficient mechanisms to repair DSBs through several pathways of homologous recombination and other nonhomologous end-joining processes. Much of our understanding of these pathways has come from the analysis of site-specific DSBs created by the HO endonuclease in the budding yeast Saccharomyces cerevisiae. I was fortunate to get in on the ground floor of analyzing the fate of synchronously induced DSBs through the study of what I coined "in vivo biochemistry...
October 3, 2016: Annual Review of Genetics
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
Maria D Molina-Sánchez, Fernando M García-Rodríguez, Nicolás Toro
The functional unit of mobile group II introns is a ribonucleoprotein particle (RNP) consisting of the intron-encoded protein (IEP) and the excised intron RNA. The IEP has reverse transcriptase activity but also promotes RNA splicing, and the RNA-protein complex triggers site-specific DNA insertion by reverse splicing, in a process called retrohoming. In vitro reconstituted ribonucleoprotein complexes from the Lactococcus lactis group II intron Ll.LtrB, which produce a double strand break, have recently been studied as a means of developing group II intron-based gene targeting methods for higher organisms...
2016: Frontiers in Molecular Biosciences
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
Huimin Zhang, Yu Hua, Rui Li, Daochun Kong
Double-stranded DNA breaks (DSBs) are highly detrimental DNA lesions, which may be repaired by the homologous recombination-mediated repair pathway. The 5 prime to 3 prime direction of long-range end resection on one DNA strand, in which 3 prime-single-strand DNA overhangs are created from broken DNA ends, is an essential step in this pathway. Dna2 has been demonstrated as an essential nuclease in this event, but the molecular mechanism how Dna2 is recruited to DNA break sites in vivo is not elucidated. In this study, a novel recombination factor called Cdc24 was identified in fission yeast...
October 11, 2016: Journal of Biological Chemistry
Xing Ma, Yingying Han, Xiaoqing Song, Trieu Do, Zhihao Yang, Jianquan Ni, Ting Xie
Stem cells in adult tissues are constantly exposed to genotoxic stress and also accumulate DNA damage with age. DNA damage has been proposed to cause stem cell loss and cancer formation. However, it remains a mystery how DNA damage leads to both stem cell loss and cancer formation. In this study, we use germline stem cells (GSCs) in the Drosophila ovary to show that DNA damage retards stem cell self-renewal and lineage differentiation in a CHK2 kinase-dependent manner. Both heatshock-inducible endonuclease I-CreI expression and X-ray irradiation can efficiently introduce double-strand breaks in GSCs and their progeny, resulting in a rapid GSC loss and an accumulation of ill-differentiated GSC progeny...
October 11, 2016: Development
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
Ilenia Pellarin, Laura Arnoldo, Silvia Costantini, Silvia Pegoraro, Gloria Ros, Carlotta Penzo, Gianluca Triolo, Francesca Demarchi, Riccardo Sgarra, Alessandro Vindigni, Guidalberto Manfioletti
The HMGA1 architectural transcription factor is an oncogene overexpressed in the vast majority of human cancers. HMGA1 is a highly connected node in the nuclear molecular network and the key aspect of HMGA1 involvement in cancer development is that HMGA1 simultaneously confers cells multiple oncogenic hits, ranging from global chromatin structural and gene expression modifications up to the direct functional alterations of key cellular proteins. Interestingly, HMGA1 also modulates DNA damage repair pathways...
2016: PloS One
Marcello Stanzione, Marek Baumann, Frantzeskos Papanikos, Ihsan Dereli, Julian Lange, Angelique Ramlal, Daniel Tränkner, Hiroki Shibuya, Bernard de Massy, Yoshinori Watanabe, Maria Jasin, Scott Keeney, Attila Tóth
DNA double-strand breaks (DSBs) are induced by SPO11 during meiosis to initiate recombination-mediated pairing and synapsis of homologous chromosomes. Germline genome integrity requires spatiotemporal control of DSB formation, which involves the proteinaceous chromosome axis along the core of each meiotic chromosome. In particular, a component of unsynapsed axes, HORMAD1, promotes DSB formation in unsynapsed regions where DSB formation must occur to ensure completion of synapsis. Despite its importance, the underlying mechanism has remained elusive...
October 10, 2016: Nature Cell Biology
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