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https://www.readbyqxmd.com/read/28930678/dna-ligase-iv-guides-end-processing-choice-during-nonhomologous-end-joining
#1
Michael P Conlin, Dylan A Reid, George W Small, Howard H Chang, Go Watanabe, Michael R Lieber, Dale A Ramsden, Eli Rothenberg
Nonhomologous end joining (NHEJ) must adapt to diverse end structures during repair of chromosome breaks. Here, we investigate the mechanistic basis for this flexibility. DNA ends are aligned in a paired-end complex (PEC) by Ku, XLF, XRCC4, and DNA ligase IV (LIG4); we show by single-molecule analysis how terminal mispairs lead to mobilization of ends within PECs and consequent sampling of more end-alignment configurations. This remodeling is essential for direct ligation of damaged and mispaired ends during cellular NHEJ, since remodeling and ligation of such ends both require a LIG4-specific structural motif, insert1...
September 19, 2017: Cell Reports
https://www.readbyqxmd.com/read/28925388/structural-step-forward-for-nhej
#2
Go Watanabe, Michael R Lieber, Dewight Williams
In a recent paper published in Cell Research, a cryo-EM structure reveals the interface between DNA-PKcs and the Ku70/80:DNA complex, together forming the DNA-dependent protein kinase holoenzyme in non-homologous DNA end joining. Insight from this structure suggests how an allosteric rearrangement of DNA-PKcs driven by Ku70/80:DNA binding regulates kinase activity in this largest member of a family of structurally homologous phosphoinositide 3-kinase-related protein kinases that includes mTOR, ATR, and ATM.
September 19, 2017: Cell Research
https://www.readbyqxmd.com/read/28914798/genome-instability-and-%C3%AE-h2ax
#3
REVIEW
Anastasios Georgoulis, Constantinos E Vorgias, George P Chrousos, Emmy P Rogakou
γH2AX has emerged in the last 20 years as a central player in the DDR (DNA damage response), with specificity for DSBs (double-strand breaks). Upon the generation of DSBs, γ-phosphorylation extends along megabase-long domains in chromatin, both sides of the damage. The significance of this mechanism is of great importance; it depicts a biological amplification mechanism where one DSB induces the γ-phosphorylation of thousands of H2AX molecules along megabaselong domains of chromatin, that are adjusted to the sites of DSBs...
September 15, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28912341/the-role-of-blm-helicase-in-homologous-recombination-gene-conversion-tract-length-and-recombination-between-diverged-sequences-in-drosophila
#4
Henry A Ertl, Daniel P Russo, Noori Srivastava, Joseph T Brooks, Thu N Dao, Jeannine R LaRocque
DNA double-strand breaks (DSBs) are a particularly deleterious class of DNA damage that threatens genome integrity. DSBs are repaired by three pathways: non-homologous end joining (NHEJ), homologous recombination (HR), and single-strand annealing (SSA). Drosophila melanogaster Blm (DmBlm) is the ortholog of Saccharomyces cerevisiae SGS1 and human BLM, and has been shown to suppress crossovers in mitotic cells and repair mitotic DNA gaps via HR. To further elucidate the role of DmBlm in repair of a simple DSB, and in particular recombination mechanisms, we utilized the DR-white and DR-white...
September 14, 2017: Genetics
https://www.readbyqxmd.com/read/28911000/dicer-regulates-non-homologous-end-joining-and-is-associated-with-chemosensitivity-in-colon-cancer-patients
#5
Xiao Chen, Wen-Feng Li, Xiaoli Wu, Heng-Chao Zhang, Li Chen, Pei-Ying Zhang, Li-Yuan Liu, Di Ma, Tongke Chen, Lingli Zhou, Yunsheng Xu, Meng-Tao Zhou, Kai-Fu Tang
DNA double-strand break (DSB) repair is an important mechanism underlying chemotherapy resistance in human cancers. Dicer participates in DSB repair by facilitating homologous recombination. However, whether Dicer is involved in non-homologous end joining (NHEJ) remains unknown. Here, we addressed whether Dicer regulates NHEJ and chemosensitivity in colon cancer cells. Using our recently developed NHEJ assay, we found that DSB introduction by I-SceI cleavage leads to Dicer upregulation. Dicer knockdown increased SIRT7 binding and decreased the level of H3K18Ac (acetylated lysine 18 of histone H3) at DSB sites, thereby repressing the recruitment of NHEJ factors to DSB sites and inhibiting NHEJ...
September 1, 2017: Carcinogenesis
https://www.readbyqxmd.com/read/28893790/combinatorial-crispr-cas9-and-rnai-attack-on-hiv-1-dna-and-rna-can-lead-to-cross-resistance
#6
Na Zhao, Gang Wang, Atze T Das, Ben Berkhout
Many potent antiviral drugs have been developed against HIV-1 and their combined action is usually successful in achieving durable virus suppression in infected individuals. This success is based on two effects: additive or even synergistic virus inhibition and an increase in the genetic threshold for development of drug-resistance. More recently, several genetic approaches have been developed to attack the HIV-1 genome in a gene therapy setting. We set out to test the combinatorial possibilities for a therapy based on the CRISPR-Cas9 and RNA interference (RNAi) mechanisms that attack the viral DNA and RNA, respectively...
September 11, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28882611/generation-and-crispr-cas9-editing-of-transformed-progenitor-b-cells-as-a-pseudo-physiological-system-to-study-dna-repair-gene-function-in-v-d-j-recombination
#7
Hélène Lenden Hasse, Chloé Lescale, Joy J Bianchi, Wei Yu, Marie Bedora-Faure, Ludovic Deriano
Antigen receptor gene assembly is accomplished in developing lymphocytes by the V(D)J recombination reaction, which can be separated into two steps: DNA cleavage by the recombination-activating gene (RAG) nuclease and joining of DNA double strand breaks (DSBs) by components of the nonhomologous end joining (NHEJ) pathway. Deficiencies for NHEJ factors can result in immunodeficiency and a propensity to accumulate genomic instability, thus highlighting the importance of identifying all players in this process and deciphering their functions...
September 4, 2017: Journal of Immunological Methods
https://www.readbyqxmd.com/read/28881569/aurora-a-kinase-regulates-non-homologous-end-joining-and-poly-adp-ribose-polymerase-function-in-ovarian-carcinoma-cells
#8
Thuy-Vy Do, Jeff Hirst, Stephen Hyter, Katherine F Roby, Andrew K Godwin
Ovarian cancer is usually diagnosed at late stages when cancer has spread beyond the ovary and patients ultimately succumb to the development of drug-resistant disease. There is an urgent and unmet need to develop therapeutic strategies that effectively treat ovarian cancer and this requires a better understanding of signaling pathways important for ovarian cancer progression. Aurora A kinase (AURKA) plays an important role in ovarian cancer progression by mediating mitosis and chromosomal instability. In the current study, we investigated the role of AURKA in regulating the DNA damage response and DNA repair in ovarian carcinoma cells...
August 1, 2017: Oncotarget
https://www.readbyqxmd.com/read/28868264/the-role-of-long-non-coding-rnas-in-the-repair-of-dna-double-strand-breaks
#9
REVIEW
Ali Dianatpour, Soudeh Ghafouri-Fard
DNA double strand breaks (DSBs) are abrasions caused in both strands of the DNA duplex following exposure to both exogenous and endogenous conditions. Such abrasions have deleterious effect in cells leading to genome rearrangements and cell death. A number of repair systems including homologous recombination (HR) and non-homologous end-joining (NHEJ) have been evolved to minimize the fatal effects of these lesions in cell. The role of protein coding genes in regulation of these pathways has been assessed previously...
2017: International Journal of Molecular and Cellular Medicine
https://www.readbyqxmd.com/read/28864683/a-crispr-cas9-based-screening-for-non-homologous-end-joining-inhibitors-reveals-ouabain-and-penfluridol-as-radiosensitizers
#10
Jie Du, Jun Shang, Fei Chen, Yushuo Zhang, Narui Yin, Ting Xie, Haowen Zhang, Jiahua Yu, Fenju Liu
Non-homologous end joining (NHEJ) is the major pathway responsible for the repair of ionizing radiation (IR)-induced DNA double-strand breaks (DSBs), and correspondingly regulates the cellular response to IR. Identification of NHEJ inhibitors could substantially enhance the tumor radiosensitivity and improve the therapeutic efficiency of radiotherapy. In present study, we demonstrated a screening for NHEJ inhibitors by using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system and high-resolution melting (HRM) analysis...
September 1, 2017: Molecular Cancer Therapeutics
https://www.readbyqxmd.com/read/28855635/highly-efficient-dna-free-gene-disruption-in-the-agricultural-pest-ceratitis-capitata-by-crispr-cas9-ribonucleoprotein-complexes
#11
Angela Meccariello, Simona Maria Monti, Alessandra Romanelli, Rita Colonna, Pasquale Primo, Maria Grazia Inghilterra, Giuseppe Del Corsano, Antonio Ramaglia, Giovanni Iazzetti, Antonia Chiarore, Francesco Patti, Svenia D Heinze, Marco Salvemini, Helen Lindsay, Elena Chiavacci, Alexa Burger, Mark D Robinson, Christian Mosimann, Daniel Bopp, Giuseppe Saccone
The Mediterranean fruitfly Ceratitis capitata (medfly) is an invasive agricultural pest of high economic impact and has become an emerging model for developing new genetic control strategies as an alternative to insecticides. Here, we report the successful adaptation of CRISPR-Cas9-based gene disruption in the medfly by injecting in vitro pre-assembled, solubilized Cas9 ribonucleoprotein complexes (RNPs) loaded with gene-specific single guide RNAs (sgRNA) into early embryos. When targeting the eye pigmentation gene white eye (we), a high rate of somatic mosaicism in surviving G0 adults was observed...
August 30, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28855246/localisation-of-double-strand-break-repair-proteins-to-viral-replication-compartments-following-lytic-reactivation-of-kshv
#12
Robert Hollingworth, Richard D Horniblow, Calum Forrest, Grant S Stewart, Roger J Grand
Double-strand breaks (DSBs) in DNA are recognised by the Ku70/80 heterodimer and the MRE11-RAD50-NBS1 (MRN) complex and result in activation of the DNA-PK and ATM kinases that play key roles in regulating the cellular DNA damage response (DDR). DNA tumour viruses such as Kaposi's sarcoma-associated herpesvirus (KSHV) are known to interact extensively with the DDR during the course of their replicative cycles. Here we show that during lytic amplification of KSHV DNA, the Ku70/80 heterodimer and the MRN complex consistently co-localise with viral genomes in replication compartments (RCs) whereas other DSB repair proteins form foci outside of RCs...
August 30, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28846869/xlf-cernunnos-an-important-but-puzzling-participant-in-the-nonhomologous-end-joining-dna-repair-pathway
#13
REVIEW
Vijay Menon, Lawrence F Povirk
DNA double strand breaks (DSBs) are one of the most deleterious DNA lesions that promote cell death, genomic instability and carcinogenesis. The two major cellular mechanisms that repair DSBs are Nonhomologous End-Joining (NHEJ) and Homologous Recombination Repair (HRR). NHEJ is the predominant pathway, in which XLF (also called Cernunnos) is a key player. Patients with XLF mutation exhibit microcephaly, lymphopenia, and growth retardation, and are immunodeficient and radiosensitive. During NHEJ, XLF interacts with XRCC4-Ligase IV, stimulates its ligase activity, and forms DNA-binding filaments of alternating XLF and XRCC4 dimers that may serve to align broken DNA and promote ligation of noncomplementary ends...
August 18, 2017: DNA Repair
https://www.readbyqxmd.com/read/28840859/cryo-em-structure-of-human-dna-pk-holoenzyme
#14
Xiaotong Yin, Mengjie Liu, Yuan Tian, Jiawei Wang, Yanhui Xu
DNA-dependent protein kinase (DNA-PK) is a serine/threonine protein kinase complex composed of a catalytic subunit (DNA-PKcs) and KU70/80 heterodimer bound to DNA. DNA-PK holoenzyme plays a critical role in non-homologous end joining (NHEJ), the major DNA repair pathway. Here, we determined cryo-electron microscopy structure of human DNA-PK holoenzyme at 6.6 Å resolution. In the complex structure, DNA-PKcs, KU70, KU80 and DNA duplex form a 650-kDa heterotetramer with 1:1:1:1 stoichiometry. The N-terminal α-solenoid (∼2 800 residues) of DNA-PKcs adopts a double-ring fold and connects the catalytic core domain of DNA-PKcs and KU70/80-DNA...
August 25, 2017: Cell Research
https://www.readbyqxmd.com/read/28827551/small-molecules-enhance-crispr-cas9-mediated-homology-directed-genome-editing-in-primary-cells
#15
Guoling Li, Xianwei Zhang, Cuili Zhong, Jianxin Mo, Rong Quan, Jie Yang, Dewu Liu, Zicong Li, Huaqiang Yang, Zhenfang Wu
CRISPR/Cas9 is an efficient customizable nuclease to generate double-strand breaks (DSBs) in the genome. This process results in knockout of the targeted gene or knock-in of a specific DNA fragment at the targeted locus in the genome of various species. However, efficiency of knock-in mediated by homology-directed repair (HDR) pathway is substantially lower compared with the efficiency of knockout mediated by the nonhomologous end-joining (NHEJ) pathway. Suppressing NHEJ pathway or enhancing HDR pathway has been proven to enhance the nuclease-mediated knock-in efficiency in cultured cells and model organisms...
August 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28827530/development-of-a-comprehensive-set-of-tools-for-genome-engineering-in-a-cold-and-thermo-tolerant-kluyveromyces-marxianus-yeast-strain
#16
Yumiko Nambu-Nishida, Keiji Nishida, Tomohisa Hasunuma, Akihiko Kondo
Kluyveromyces marxianus, a non-conventional thermotolerant yeast, is potentially useful for production of ethanol and other products. This species has a strong tendency to randomly integrate transforming DNA fragments, making necessary the development of more precise methods for gene targeting. In this study, we first demonstrated that K. marxianus NBRC1777 is cold-tolerant, and then established a highly efficient and precise technique for gene editing by introducing genes encoding deaminase-mediated targeted point mutagenesis (Target-AID) and clustered regularly interspaced short palindromic repeats (CRISPR) associated proteins (CRISPR-Cas9)...
August 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28827033/inhibition-of-parp1-activity-enhances-chemotherapeutic-efficiency-in-cisplatin-resistant-gastric-cancer-cells
#17
Qiang Wang, Jianping Xiong, Danping Qiu, Xue Zhao, Donglin Yan, Wenxia Xu, Zhangding Wang, Qi Chen, Sapna Panday, Aiping Li, Shouyu Wang, Jianwei Zhou
Cisplatin (DDP) is the first line chemotherapeutic drug for several cancers, including gastric cancer (GC). Unfortunately, the rapid development of drug resistance remains a significant challenge for the clinical application of cisplatin. There is an urgent need to develop new strategies to overcome DDP resistance for cancer treatment. In this study, four types of human GC cells have been divided into naturally sensitive or naturally resistant categories according to their responses to cisplatin. PARP1 activity (poly (ADP-ribose), PAR) was found to be greatly increased in cisplatin-resistant GC cells...
August 4, 2017: International Journal of Biochemistry & Cell Biology
https://www.readbyqxmd.com/read/28822858/comparison-of-genome-engineering-using-the-crispr-cas9-system-in-c-glabrata-wild-type-and-lig4-strains
#18
Yuke Cen, Bea Timmermans, Ben Souffriau, Johan M Thevelein, Patrick Van Dijck
Candida glabrata is reported as the second most prevalent human opportunistic fungal pathogen in North America and is threatening patients all over the world. Its incidence is rising, while it has developed resistance to the most widely used antifungal drugs, necessitating new approaches based on better insight into the biology of the organism. Despite its close phylogenetic relationship with Saccharomyces cerevisiae, generating precise genomic alterations in this species is problematic. Previously we have shown that deletion of LIG4, which encodes an enzyme involved in Non-Homologous End Joining (NHEJ), strongly enhances the probability of obtaining correctly modified transformants...
October 2017: Fungal Genetics and Biology: FG & B
https://www.readbyqxmd.com/read/28808289/gene-editing-in-clinical-isolates-of-candida-parapsilosis-using-crispr-cas9
#19
Lisa Lombardi, Siobhán A Turner, Fang Zhao, Geraldine Butler
Candida parapsilosis is one of the most common causes of candidiasis, particularly in the very young and the very old. Studies of gene function are limited by the lack of a sexual cycle, the diploid genome, and a paucity of molecular tools. We describe here the development of a plasmid-based CRISPR-Cas9 system for gene editing in C. parapsilosis. A major advantage of the system is that it can be used in any genetic background, which we showed by editing genes in 20 different isolates. Gene editing is carried out in a single transformation step...
August 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28801308/egfr-mutations-compromise-hypoxia-associated-radiation-resistance-through-impaired-replication-fork-associated-dna-damage-repair
#20
Mohammad Saki, Haruhiko Makino, Prashanthi Javvadi, Nozomi Tomimatsu, Lianghao Ding, Jennifer E Clark, Elaine Gavin, Kenichi Takeda, Joel Andrews, Debabrata Saha, Michael D Story, Sandeep Burma, Chaitanya Nirodi
Epidermal growth factor receptor (EGFR) signaling has been implicated in hypoxia-associated resistance to radiation or chemotherapy. Non-small cell lung carcinomas (NSCLC) with activating L858R or ΔE746-E750 EGFR mutations exhibit elevated EGFR activity and downstream signaling. Here, relative to wild type (WT) EGFR, mutant (MT) EGFR expression significantly increases radiosensitivity in hypoxic cells. Gene expression profiling in human bronchial epithelial cells (HBEC) revealed that MT-EGFR expression elevated transcripts related to cell cycle and replication in aerobic and hypoxic conditions and down-regulated RAD50, a critical component of non-homologous end-joining (NHEJ) and homologous recombination (HR) DNA repair pathways...
August 11, 2017: Molecular Cancer Research: MCR
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