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non-homologous end-joining

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https://www.readbyqxmd.com/read/29036662/parp2-controls-double-strand-break-repair-pathway-choice-by-limiting-53bp1-accumulation-at-dna-damage-sites-and-promoting-end-resection
#1
Alexis Fouquin, Josée Guirouilh-Barbat, Bernard Lopez, Janet Hall, Mounira Amor-Guéret, Vincent Pennaneach
Double strand breaks (DSBs) are one of the most toxic lesions to cells. DSB repair by the canonical non-homologous end-joining (C-EJ) pathway involves minor, if any, processing of the broken DNA-ends, whereas the initiation of DNA resection channels the broken-ends toward DNA repair pathways using various lengths of homology. Mechanisms that control the resection initiation are thus central to the regulation to the choice of DSB repair pathway. Therefore, understanding the mechanisms which regulate the initiation of DNA end-resection is of prime importance...
October 3, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/29019352/hot-news-gene-therapy-with-crispr-cas9-coming-to-age-for-hiv-cure
#2
Vicente Soriano
The huge success of current antiretroviral therapy is mediated by a triple effect: (i) Halting progression to AIDS in infected persons; (ii) reducing the risk of transmission to contacts (treatment as prevention); and (iii) minimizing the risk of HIV acquisition treating uninfected persons at risk (pre-exposure prophylaxis). However, UNAIDS has estimated that only 70% of infected people globally are diagnosed, only 53% are treated, and overall 44% have undetectable viral load, which is the necessary request for ensuring any antiretroviral benefit...
October 11, 2017: AIDS Reviews
https://www.readbyqxmd.com/read/29018935/a-curious-new-role-for-mrn-in-schizosaccharomyces-pombe-non-homologous-end-joining
#3
REVIEW
Kurt W Runge, Yanhui Li
Chromosomal breaks can be healed by several repair processes, including one called non-homologous end-joining (NHEJ) where the two broken ends are ligated together with a loss of 0-5 bp of DNA. The protein requirements for NHEJ of cut DNA ends in the budding yeast Saccharomyces cerevisiae include its version of the Mre11-Rad50-Nbs1 (MRN) complex. In contrast, the fission yeast Schizosaccharomyces pombe and mammalian cells do not require MRN for this process. Recent work in S. pombe used transposon excision to generate breaks that were capped by DNA hairpins, which must be opened to produce ligatable ends...
October 10, 2017: Current Genetics
https://www.readbyqxmd.com/read/28993682/olaparib-modulates-dna-repair-efficiency-sensitizes-cervical-cancer-cells-to-cisplatin-and-exhibits-anti-metastatic-property
#4
Chandra Bhushan Prasad, Shyam Babu Prasad, Suresh Singh Yadav, Laxmi Kant Pandey, Sunita Singh, Satyajit Pradhan, Gopeshwar Narayan
PARP1 trapping at DNA lesion by pharmacological inhibitors has been exploited in several cancers exhibiting defects in DNA repair mechanisms. PARP1 hyperactivation is involved in therapeutic resistance in multiple cancers. The role of PARP1 in cervical cancer (CC) resistance and implication of PARP inhibitor is yet to be elucidated. Our data demonstrates significantly higher expression of PARP1 in primary cervical tumors and CC cell lines SiHa and ME180. Upon cisplatin treatment CC cells display significant overexpression of PARP1 and its hyperactivation...
October 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28988985/facs-assisted-crispr-cas9-genome-editing-facilitates-parkinson-s-disease-modeling
#5
Jonathan Arias-Fuenzalida, Javier Jarazo, Xiaobing Qing, Jonas Walter, Gemma Gomez-Giro, Sarah Louise Nickels, Holm Zaehres, Hans Robert Schöler, Jens Christian Schwamborn
Genome editing and human induced pluripotent stem cells hold great promise for the development of isogenic disease models and the correction of disease-associated mutations for isogenic tissue therapy. CRISPR-Cas9 has emerged as a versatile and simple tool for engineering human cells for such purposes. However, the current protocols to derive genome-edited lines require the screening of a great number of clones to obtain one free of random integration or on-locus non-homologous end joining (NHEJ)-containing alleles...
September 26, 2017: Stem Cell Reports
https://www.readbyqxmd.com/read/28987344/uncharacterized-orf-hur1-influences-the-efficiency-of-non-homologous-end-joining-repair-in-saccharomyces-cerevisiae
#6
Katayoun Omidi, Matthew Jessulat, Mohsen Hooshyar, Daniel Burnside, Andrew Schoenrock, Tom Kazmirchuk, Maryam Hajikarimlou, Mary Daniel, Houman Moteshareie, Urvi Bhojoo, Megan Sanders, Dindial Ramotar, Frank Dehne, Bahram Samanfar, Mohan Babu, Ashkan Golshani
Non-Homologous End Joining (NHEJ) is a highly conserved pathway that repairs Double-Strand Breaks (DSBs) within DNA. Here we show that the deletion of yeast uncharacterized ORF HUR1, Hydroxyurea Resistance1 affects the efficiency of NHEJ. Our findings are supported by Protein-Protein Interaction (PPI), genetic interaction and drug sensitivity analyses. To assess the activity of HUR1 in DSB repair, we deleted its non-overlapping region with PMR1, referred to as HUR1-A. We observed that similar to deletion of TPK1 and NEJ1, and unlike YKU70 (important for NHEJ of DNA with overhang and not blunt end), deletion of HUR1-A reduced the efficiency of NHEJ in both overhang and blunt end plasmid repair assays...
October 4, 2017: Gene
https://www.readbyqxmd.com/read/28985363/protein-phosphatase-1-and-phosphatase-1-nuclear-targeting-subunit-dependent-regulation-of-dna-dependent-protein-kinase-and-non-homologous-end-joining
#7
Songli Zhu, Laura A Fisher, Tadayoshi Bessho, Aimin Peng
DNA-dependent protein kinase catalytic subunit (DNA-PKcs) plays a key role in mediating non-homologous end joining (NHEJ), a major repair pathway for DNA double-strand breaks (DSBs). The activation, function and dynamics of DNA-PKcs is regulated largely by its reversible phosphorylation at numerous residues, many of which are targeted by DNA-PKcs itself. Interestingly, these DNA-PKcs phosphorylation sites function in a distinct, and sometimes opposing manner, suggesting that they are differentially regulated via complex actions of both kinases and phosphatases...
August 2, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28977657/h2ax-facilitates-classical-non-homologous-end-joining-at-the-expense-of-limited-nucleotide-loss-at-repair-junctions
#8
Yi-Li Feng, Ji-Feng Xiang, Si-Cheng Liu, Tao Guo, Guo-Fang Yan, Ye Feng, Na Kong, Hao-Dan Li, Yang Huang, Hui Lin, Xiu-Jun Cai, An-Yong Xie
Phosphorylated histone H2AX, termed 'γH2AX', mediates the chromatin response to DNA double strand breaks (DSBs) in mammalian cells. H2AX deficiency increases the numbers of unrepaired DSBs and translocations, which are partly associated with defects in non-homologous end joining (NHEJ) and contributing to genomic instability in cancer. However, the role of γH2AX in NHEJ of general DSBs has yet to be clearly defined. Here, we showed that despite little effect on overall NHEJ efficiency, H2AX deficiency causes a surprising bias towards accurate NHEJ and shorter deletions in NHEJ products...
August 10, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28974511/tox-regulates-growth-dna-repair-and-genomic-instability-in-t-cell-acute-lymphoblastic-leukemia
#9
Riadh Lobbardi, Jordan Pinder, Barbara Martinez-Pastor, Marina Theodorou, Jessica S Blackburn, Brian J Abraham, Yuka Namiki, Marc Mansour, Nouran S Abdelfattah, Aleksey Molodtsov, Gabriela Alexe, Debra Toiber, Manon de Waard, Esha Jain, Myriam Boukhali, Mattia Lion, Deepak Bhere, Khalid Shah, Alejandro Gutierrez, Kimberly Stegmaier, Lewis B Silverman, Ruslan I Sadreyev, John M Asara, Marjorie A Oettinger, Wilhelm Haas, A Thomas Look, Richard A Young, Raul Mostoslavsky, Graham Dellaire, David M Langenau
T-cell Acute Lymphoblastic Leukemia (T-ALL) is an aggressive malignancy of thymocytes. Using a transgenic screen in zebrafish, thymocyte selection-associated high mobility box protein (TOX) was uncovered as a collaborating oncogenic driver that accelerated T-ALL onset by expanding the initiating pool of transformed clones and elevating genomic instability. TOX is highly expressed in a majority of human T-ALL and is required for proliferation and continued xenograft growth in mice. Using a wide array of functional analyses, we uncovered that TOX binds directly to KU70/80 and suppresses recruitment of this complex to DNA breaks to inhibit Non-Homologous End Joining repair (NHEJ)...
October 3, 2017: Cancer Discovery
https://www.readbyqxmd.com/read/28973445/redundancy-between-nucleases-required-for-homologous-recombination-promotes-parp-inhibitor-resistance-in-the-eukaryotic-model-organism-dictyostelium
#10
Anna-Lena Kolb, Alasdair R Gunn, Nicholas D Lakin
ADP-ribosyltransferases promote repair of DNA single strand breaks and disruption of this pathway by Poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi) is toxic to cells with defects in homologous recombination (HR). Here, we show that this relationship is conserved in the simple eukaryote Dictyostelium and exploit this organism to define mechanisms that drive resistance of the HR-deficient cells to PARPi. Dictyostelium cells disrupted in exonuclease I, a critical factor for HR, are sensitive to PARPi. Deletion of exo1 prevents the accumulation of Rad51 in chromatin induced by PARPi, resulting in DNA damage being channelled through repair by non-homologous end-joining (NHEJ)...
September 29, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28973441/pol%C3%AE-tumor-variants-decrease-the-efficiency-and-accuracy-of-nhej
#11
Guillermo Sastre-Moreno, John M Pryor, Alberto Díaz-Talavera, José F Ruiz, Dale A Ramsden, Luis Blanco
The non homologous end-joining (NHEJ) pathway of double-strand break (DSB) repair often requires DNA synthesis to fill the gaps generated upon alignment of the broken ends, a complex task performed in human cells by two specialized DNA polymerases, Polλ and Polμ. It is now well established that Polμ is the one adapted to repair DSBs with non-complementary ends, the most challenging scenario, although the structural basis and physiological implications of this adaptation are not fully understood. Here, we demonstrate that two human Polμ point mutations, G174S and R175H, previously identified in two different tumor samples and affecting two adjacent residues, limit the efficiency of accurate NHEJ by Polμ in vitro and in vivo...
September 29, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28973384/characterization-of-breakpoint-regions-of-large-structural-autosomal-mosaic-events
#12
Mitchell J Machiela, Lea Jessop, Weiyin Zhou, Meredith Yeager, Stephen J Chanock
Recent studies have reported a higher than anticipated frequency of large clonal autosomal mosaic events >2 Mb in size in the aging population. Mosaic events are detected from analyses of intensity parameters of linear stretches with deviations in heterozygous probes of single nucleotide polymorphism (SNP) microarrays. The non-random distribution of detected mosaic events throughout the genome suggests common mechanisms could influence the formation of mosaic events. Here we use publicly available data tracks from the University of California Santa Cruz Genome Browser to investigate the genomic characteristics of the regions at the terminal ends of two frequent types of large structural mosaic events: telomeric neutral events and interstitial losses...
August 16, 2017: Human Molecular Genetics
https://www.readbyqxmd.com/read/28963924/efficient-repair-of-dna-double-strand-breaks-in-individuals-from-high-level-natural-radiation-areas-of-kerala-coast-south-west-india
#13
Vinay Jain, Divyalakshmi Saini, P R Vivek Kumar, G Jaikrishan, Birajalaxmi Das
High level natural radiation areas (HLNRA) of Kerala coastal strip (55km long and 0.5km wide) in southwest India exhibit wide variations in the level of background dose (< 1.0-45.0mGy/year) due to thorium deposits in the beach sand. The areas with ≤1.5mGy/year are considered as normal level natural radiation area (NLNRA), whereas areas with >1.5mGy/year are HLNRA. Individuals belonging to HLNRA were stratified into two groups, Low dose group (LDG: 1.51-5.0mGy/year) and high dose group (HDG: >5.0mGy/year)...
September 20, 2017: Mutation Research
https://www.readbyqxmd.com/read/28959974/regulation-of-dna-repair-pathway-choice-in-s-and-g2-phases-by-the-nhej-inhibitor-cyren
#14
Nausica Arnoult, Adriana Correia, Jiao Ma, Anna Merlo, Sara Garcia-Gomez, Marija Maric, Marco Tognetti, Christopher W Benner, Simon J Boulton, Alan Saghatelian, Jan Karlseder
Classical non-homologous end joining (cNHEJ) and homologous recombination compete for the repair of double-stranded DNA breaks during the cell cycle. Homologous recombination is inhibited during the G1 phase of the cell cycle, but both pathways are active in the S and G2 phases. However, it is unclear why cNHEJ does not always outcompete homologous recombination during the S and G2 phases. Here we show that CYREN (cell cycle regulator of NHEJ) is a cell-cycle-specific inhibitor of cNHEJ. Suppression of CYREN allows cNHEJ to occur at telomeres and intrachromosomal breaks during the S and G2 phases, and cells lacking CYREN accumulate chromosomal aberrations upon damage induction, specifically outside the G1 phase...
September 20, 2017: Nature
https://www.readbyqxmd.com/read/28952912/measurement-of-dna-dependent-protein-kinase-phosphorylation-using-flow-cytometry-provides-a-reliable-estimate-of-dna-repair-capacity
#15
Andris Abramenkovs, Bo Stenerlöw
Uncontrolled generation of DNA double-strand breaks (DSBs) in cells is regarded as a highly toxic event that threatens cell survival. Radiation-induced DNA DSBs are commonly measured by pulsed-field gel electrophoresis, microscopic evaluation of accumulating DNA damage response proteins (e.g., 53BP1 or γ-H2AX) or flow cytometric analysis of γ-H2AX. The advantage of flow cytometric analysis is that DSB formation and repair can be studied in relationship to cell cycle phase or expression of other proteins. However, γ-H2AX is not able to monitor repair kinetics within the first 60 min postirradiation, a period when most DSBs undergo repair...
September 27, 2017: Radiation Research
https://www.readbyqxmd.com/read/28945226/pten-deficiency-sensitizes-endometrioid-endometrial-cancer-to-compound-parp-pi3k-inhibition-but-not-parp-inhibition-as-monotherapy
#16
X Bian, J Gao, F Luo, C Rui, T Zheng, D Wang, Y Wang, T M Roberts, P Liu, J J Zhao, H Cheng
Poly (ADP-ribose) polymerase (PARP) inhibitors have emerged as promising cancer therapeutics especially for tumors with deficient homologous recombination (HR) repair. However, as HR-deficient tumors represent only a small fraction of endometrial cancers, the therapeutic utility of PARP inhibitors is limited in this disease. Somatic loss of phosphatase and tensin homolog (PTEN), a tumor suppressor that counteracts phosphoinositide 3-kinase (PI3K) activity, is one of the most common genetic aberrations in endometrioid endometrial cancer...
September 25, 2017: Oncogene
https://www.readbyqxmd.com/read/28943310/asf1a-promotes-non-homologous-end-joining-repair-by-facilitating-phosphorylation-of-mdc1-by-atm-at-double-strand-breaks
#17
Kyung Yong Lee, Jun-Sub Im, Etsuko Shibata, Anindya Dutta
Double-strand breaks (DSBs) of DNA in eukaryotic cells are predominantly repaired by non-homologous end joining (NHEJ). The histone chaperone anti-silencing factor 1a (ASF1a) interacts with MDC1 and is recruited to sites of DSBs to facilitate the interaction of phospho-ATM with MDC1 and phosphorylation of MDC1, which are required for the recruitment of RNF8/RNF168 histone ubiquitin ligases. Thus, ASF1a deficiency reduces histone ubiquitination at DSBs, decreasing the recruitment of 53BP1, and decreases NHEJ, rendering cells more sensitive to DSBs...
October 5, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28939824/in-trans-paired-nicking-triggers-seamless-genome-editing-without-double-stranded-dna-cutting
#18
Xiaoyu Chen, Josephine M Janssen, Jin Liu, Ignazio Maggio, Anke E J 't Jong, Harald M M Mikkers, Manuel A F V Gonçalves
Precise genome editing involves homologous recombination between donor DNA and chromosomal sequences subjected to double-stranded DNA breaks made by programmable nucleases. Ideally, genome editing should be efficient, specific, and accurate. However, besides constituting potential translocation-initiating lesions, double-stranded DNA breaks (targeted or otherwise) are mostly repaired through unpredictable and mutagenic non-homologous recombination processes. Here, we report that the coordinated formation of paired single-stranded DNA breaks, or nicks, at donor plasmids and chromosomal target sites by RNA-guided nucleases based on CRISPR-Cas9 components, triggers seamless homology-directed gene targeting of large genetic payloads in human cells, including pluripotent stem cells...
September 22, 2017: Nature Communications
https://www.readbyqxmd.com/read/28936671/use-of-the-cas9-orthologs-from-streptococcus-thermophilus-and-staphylococcus-aureus-for-non-homologous-end-joining-mediated-site-specific-mutagenesis-in-arabidopsis-thaliana
#19
Jeannette Steinert, Carla Schmidt, Holger Puchta
Since the discovery of the CRISPR/Cas system and its in vivo application for site-specific targeted mutagenesis, this technique is wildly used in a great variety of organisms, such as many plant species. Commonly used for this application is the Cas9 enzyme from Streptococcus pyogenes. Here, we describe the application of two Cas9 orthologs from Streptococcus thermophilus and Staphylococcus aureus for targeted non-homologous end-joining mediated mutagenesis in Arabidopsis thaliana. With both orthologs, we could show efficient inheritance of the induced mutations...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28934497/systematic-analysis-of-dna-crosslink-repair-pathways-during-development-and-aging-in-caenorhabditis-elegans
#20
David M Wilson, Matthias Rieckher, Ashley B Williams, Björn Schumacher
DNA interstrand crosslinks (ICLs) are generated by endogenous sources and chemotherapeutics, and pose a threat to genome stability and cell survival. Using Caenorhabditis elegans mutants, we identify DNA repair factors that protect against the genotoxicity of ICLs generated by trioxsalen/ultraviolet A (TMP/UVA) during development and aging. Mutations in nucleotide excision repair (NER) components (e.g. XPA-1 and XPF-1) imparted extreme sensitivity to TMP/UVA relative to wild-type animals, manifested as developmental arrest, defects in adult tissue morphology and functionality, and shortened lifespan...
September 19, 2017: Nucleic Acids Research
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