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https://www.readbyqxmd.com/read/28096467/mir-21-mediated-radioresistance-is-via-promoting-repair-of-dna-double-strand-breaks
#1
Baocheng Hu, Xiang Wang, Suofeng Hu, Xiaomin Ying, Ping Wang, Xiangming Zhang, Jian Wang, Hongyan Wang, Ya Wang
MiR-21 as an oncogene that over-expresses in most human tumors involves radioresistance; however, the mechanism remains unclear. Here, we demonstrate that miR-21-mediated radioresistance is through promoting repair of DNA double strand breaks, which includes to facilitate both non-homologous end-joining (NHEJ) and homologous recombination repair (HRR). The miR-21-promoted NHEJ is through targeting GSK3B (a novel target of miR-21) that affects the CRY2/PP5 pathway and in turn increases DNA-PKcs activity. The miR-21-promoted HRR is through targeting both GSK3B and CDC25A (a known target of miR-21), which neutralizes the effects of targeting GSK3B-induced CDC25A increase since GSK3B promotes degradation of both CDC25A and Cyclin D1, but CDC25A and Cyclin D1 have an opposite effect on HRR...
January 17, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28074659/ferulic-acid-fa-abrogates-%C3%AE-radiation-induced-oxidative-stress-and-dna-damage-by-up-regulating-nuclear-translocation-of-nrf2-and-activation-of-nhej-pathway
#2
Ujjal Das, Krishnendu Manna, Amitava Khan, Mahuya Sinha, Sushobhan Biswas, Aaveri Sengupta, Anindita Chakraborty, Sanjit Dey
The present study was aimed to evaluate the radioprotective effect of ferulic acid (FA), a naturally occurring plant flavonoid in terms of DNA damage and damage related alterations of repair pathways by gamma radiation. FA was administered at a dose of 50 mg/kg body weight for five consecutive days prior to exposing the swiss albino mice to a single dose of 10 Gy gamma radiation. Ionising radiation induces oxidative damage manifested by decreased expression of Cu, Zn-SOD (SOD stands for super oxide dismutase), Mn-SOD and catalase...
January 11, 2017: Free Radical Research
https://www.readbyqxmd.com/read/28067485/honokiol-inhibits-dna-polymerases-%C3%AE-and-%C3%AE-and-increases-bleomycin-sensitivity-of-human-cancer-cells
#3
Prakasha Gowda, Zucai Suo, Thomas E Spratt
A major concept to sensitize cancer cells to DNA damaging agents is by inhibiting proteins in the DNA repair pathways. X-Family DNA polymerases play critical roles in both base excision repair (BER) and non-homologous end joining (NHEJ). In this study, we examined the effectiveness of honokiol to inhibit human DNA polymerase β (pol β), which is involved in BER, and DNA polymerase λ (pol λ), which is involved in NHEJ. Kinetic analysis with purified showed that honokiol inhibited DNA polymerase activity. The inhibition mode for the polymerases was a mixed-function noncompetitive inhibition with respect to the substrate, dCTP...
January 9, 2017: Chemical Research in Toxicology
https://www.readbyqxmd.com/read/28057860/contribution-of-canonical-nonhomologous-end-joining-to-chromosomal-rearrangements-is-enhanced-by-atm-kinase-deficiency
#4
Ragini Bhargava, Caree R Carson, Gabriella Lee, Jeremy M Stark
A likely mechanism of chromosomal rearrangement formation involves joining the ends from two different chromosomal double-strand breaks (DSBs). These events could potentially be mediated by either of two end-joining (EJ) repair pathways [canonical nonhomologous end joining (C-NHEJ) or alternative end joining (ALT-EJ)], which cause distinct rearrangement junction patterns. The relative role of these EJ pathways during rearrangement formation has remained controversial. Along these lines, we have tested whether the DNA damage response mediated by the Ataxia Telangiectasia Mutated (ATM) kinase may affect the relative influence of C-NHEJ vs...
January 5, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28053662/development-of-a-genome-editing-crispr-cas9-system-in-thermophilic-fungal-myceliophthora-species-and-its-application-to-hyper-cellulase-production-strain-engineering
#5
Qian Liu, Ranran Gao, Jingen Li, Liangcai Lin, Junqi Zhao, Wenliang Sun, Chaoguang Tian
BACKGROUND: Over the past 3 years, the CRISPR/Cas9 system has revolutionized the field of genome engineering. However, its application has not yet been validated in thermophilic fungi. Myceliophthora thermophila, an important thermophilic biomass-degrading fungus, has attracted industrial interest for the production of efficient thermostable enzymes. Genetic manipulation of Myceliophthora is crucial for metabolic engineering and to unravel the mechanism of lignocellulose deconstruction...
2017: Biotechnology for Biofuels
https://www.readbyqxmd.com/read/28051062/paxx-promotes-ku-accumulation-at-dna-breaks-and-is-essential-for-end-joining-in-xlf-deficient-mice
#6
Xiangyu Liu, Zhengping Shao, Wenxia Jiang, Brian J Lee, Shan Zha
Non-homologous end-joining (NHEJ) is the most prominent DNA double strand break (DSB) repair pathway in mammalian cells. PAXX is the newest NHEJ factor, which shares structural similarity with known NHEJ factors-XRCC4 and XLF. Here we report that PAXX is dispensable for physiological NHEJ in otherwise wild-type mice. Yet Paxx(-/-) mice require XLF and Xlf(-/-) mice require PAXX for end-ligation. As such, Xlf(-/-)Paxx(-/-) mice display severe genomic instability and neuronal apoptosis, which eventually lead to embryonic lethality...
January 4, 2017: Nature Communications
https://www.readbyqxmd.com/read/28046013/homologous-recombination-defective-arabidopsis-mutants-exhibit-enhanced-sensitivity-to-abscisic-acid
#7
Sujit Roy, Kali Pada Das
Abscisic acid (ABA) acts as an important plant hormone in regulating various aspects of plant growth and developmental processes particularly under abiotic stress conditions. An increased ABA level in plant cells inhibits DNA replication and cell division, causing plant growth retardation. In this study, we have investigated the effects of ABA on the growth responses of some major loss-of-function mutants of DNA double-stand break (DSB) repair genes in Arabidopsis during seed germination and early stages of seedling growth for understanding the role of ABA in the induction of genome instability in plants...
2017: PloS One
https://www.readbyqxmd.com/read/28030852/drug-induced-premature-senescence-model-in-human-dental-follicle-stem-cells
#8
Yuanfen Zhai, Rongbin Wei, Junjun Liu, Huihui Wang, Wenping Cai, Mengmeng Zhao, Yongguang Hu, Shuwei Wang, Tianshu Yang, Xiaodong Liu, Jianhua Yang, Shangfeng Liu
Aging is identified by a progressive decline of physiological integrity leading to age-related degenerative diseases, but its causes is unclear. Human dental pulp stem cells (hDPSCs) has a remarkable rejuvenated capacity that relies on its resident stem cells. However, because of the lack of proper senescence models, exploration of the underlying molecular mechanisms has been hindered. Here, we established a cellular model utilizing a hydroxyurea (HU) treatment protocol and effectively induced Human dental pulp stem cells to undergo cellular senescence...
December 21, 2016: Oncotarget
https://www.readbyqxmd.com/read/27994036/microhomology-mediated-end-joining-is-activated-in-irradiated-human-cells-due-to-phosphorylation-dependent-formation-of-the-xrcc1-repair-complex
#9
Arijit Dutta, Bradley Eckelmann, Sanjay Adhikari, Kazi Mokim Ahmed, Shiladitya Sengupta, Arvind Pandey, Pavana M Hegde, Miaw-Sheue Tsai, John A Tainer, Michael Weinfeld, Muralidhar L Hegde, Sankar Mitra
Microhomology-mediated end joining (MMEJ), an error-prone pathway for DNA double-strand break (DSB) repair, is implicated in genomic rearrangement and oncogenic transformation; however, its contribution to repair of radiation-induced DSBs has not been characterized. We used recircularization of a linearized plasmid with 3'-P-blocked termini, mimicking those at X-ray-induced strand breaks, to recapitulate DSB repair via MMEJ or nonhomologous end-joining (NHEJ). Sequence analysis of the circularized plasmids allowed measurement of relative activity of MMEJ versus NHEJ...
December 19, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27965636/multiple-and-variable-nhej-like-genes-are-involved-in-resistance-to-dna-damage-in-streptomyces-ambofaciens
#10
Grégory Hoff, Claire Bertrand, Lingli Zhang, Emilie Piotrowski, Ludovic Chipot, Cyril Bontemps, Fabrice Confalonieri, Stephen McGovern, François Lecointe, Annabelle Thibessard, Pierre Leblond
Non-homologous end-joining (NHEJ) is a double strand break (DSB) repair pathway which does not require any homologous template and can ligate two DNA ends together. The basic bacterial NHEJ machinery involves two partners: the Ku protein, a DNA end binding protein for DSB recognition and the multifunctional LigD protein composed a ligase, a nuclease and a polymerase domain, for end processing and ligation of the broken ends. In silico analyses performed in the 38 sequenced genomes of Streptomyces species revealed the existence of a large panel of NHEJ-like genes...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27956611/biasing-genome-editing-events-toward-precise-length-deletions-with-an-rna-guided-tevcas9-dual-nuclease
#11
Jason M Wolfs, Thomas A Hamilton, Jeremy T Lant, Marcon Laforet, Jenny Zhang, Louisa M Salemi, Gregory B Gloor, Caroline Schild-Poulter, David R Edgell
The CRISPR/Cas9 nuclease is commonly used to make gene knockouts. The blunt DNA ends generated by cleavage can be efficiently ligated by the classical nonhomologous end-joining repair pathway (c-NHEJ), regenerating the target site. This repair creates a cycle of cleavage, ligation, and target site regeneration that persists until sufficient modification of the DNA break by alternative NHEJ prevents further Cas9 cutting, generating a heterogeneous population of insertions and deletions typical of gene knockouts...
December 27, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27926866/inflammation-induced-oxidative-stress-mediates-gene-fusion-formation-in-prostate-cancer
#12
Ram S Mani, Mohammad A Amin, Xiangyi Li, Shanker Kalyana-Sundaram, Brendan A Veeneman, Lei Wang, Aparna Ghosh, Adam Aslam, Susmita G Ramanand, Bradley J Rabquer, Wataru Kimura, Maxwell Tran, Xuhong Cao, Sameek Roychowdhury, Saravana M Dhanasekaran, Nallasivam Palanisamy, Hesham A Sadek, Payal Kapur, Alisa E Koch, Arul M Chinnaiyan
Approximately 50% of prostate cancers are associated with gene fusions of the androgen-regulated gene TMPRSS2 to the oncogenic erythroblast transformation-specific (ETS) transcription factor ERG. The three-dimensional proximity of TMPRSS2 and ERG genes, in combination with DNA breaks, facilitates the formation of TMPRSS2-ERG gene fusions. However, the origins of DNA breaks that underlie gene fusion formation in prostate cancers are far from clear. We demonstrate a role for inflammation-induced oxidative stress in the formation of DNA breaks leading to recurrent TMPRSS2-ERG gene fusions...
December 6, 2016: Cell Reports
https://www.readbyqxmd.com/read/27924007/bridging-of-double-stranded-breaks-by-the-nonhomologous-end-joining-ligation-complex-is-modulated-by-dna-end-chemistry
#13
Dylan A Reid, Michael P Conlin, Yandong Yin, Howard H Chang, Go Watanabe, Michael R Lieber, Dale A Ramsden, Eli Rothenberg
The nonhomologous end-joining (NHEJ) pathway is the primary repair pathway for DNA double strand breaks (DSBs) in humans. Repair is mediated by a core complex of NHEJ factors that includes a ligase (DNA Ligase IV; L4) that relies on juxtaposition of 3' hydroxyl and 5' phosphate termini of the strand breaks for catalysis. However, chromosome breaks arising from biological sources often have different end chemistries, and how these different end chemistries impact the way in which the core complex directs the necessary transitions from end pairing to ligation is not known...
December 6, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27924002/sfpq%C3%A2-nono-and-xlf-function-separately-and-together-to-promote-dna-double-strand-break-repair-via-canonical-nonhomologous-end-joining
#14
Lahcen Jaafar, Zhentian Li, Shuyi Li, William S Dynan
A complex of two related mammalian proteins, SFPQ and NONO, promotes DNA double-strand break repair via the canonical nonhomologous end joining (c-NHEJ) pathway. However, its mechanism of action is not fully understood. Here we describe an improved SFPQ•NONO-dependent in vitro end joining assay. We use this system to demonstrate that the SFPQ•NONO complex substitutes in vitro for the core c-NHEJ factor, XLF. Results are consistent with a model where SFPQ•NONO promotes sequence-independent pairing of DNA substrates, albeit in a way that differs in detail from XLF...
December 6, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27922005/wrn-regulates-pathway-choice-between-classical-and-alternative-non-homologous-end-joining
#15
Raghavendra A Shamanna, Huiming Lu, Jessica K de Freitas, Jane Tian, Deborah L Croteau, Vilhelm A Bohr
Werner syndrome (WS) is an accelerated ageing disorder with genomic instability caused by WRN protein deficiency. Many features seen in WS can be explained by the diverse functions of WRN in DNA metabolism. However, the origin of the large genomic deletions and telomere fusions are not yet understood. Here, we report that WRN regulates the pathway choice between classical (c)- and alternative (alt)-nonhomologous end joining (NHEJ) during DNA double-strand break (DSB) repair. It promotes c-NHEJ via helicase and exonuclease activities and inhibits alt-NHEJ using non-enzymatic functions...
December 6, 2016: Nature Communications
https://www.readbyqxmd.com/read/27921283/choices-have-consequences-the-nexus-between-dna-repair-pathways-and-genomic-instability-in-cancer
#16
REVIEW
Sonali Bhattacharjee, Saikat Nandi
BACKGROUND: The genome is under constant assault from a multitude of sources that can lead to the formation of DNA double-stand breaks (DSBs). DSBs are cytotoxic lesions, which if left unrepaired could lead to genomic instability, cancer and even cell death. However, erroneous repair of DSBs can lead to chromosomal rearrangements and loss of heterozygosity, which in turn can also cause cancer and cell death. Hence, although the repair of DSBs is crucial for the maintenance of genome integrity the process of repair need to be well regulated and closely monitored...
December 2016: Clinical and Translational Medicine
https://www.readbyqxmd.com/read/27915381/regulation-of-non-homologous-end-joining-via-post-translational-modifications-of-components-of-the-ligation-step
#17
REVIEW
Kristína Durdíková, Miroslav Chovanec
DNA double-strand breaks are the most serious type of DNA damage and non-homologous end joining (NHEJ) is an important pathway for their repair. In Saccharomyces cerevisiae, three complexes mediate the canonical NHEJ pathway, Ku (Ku70/Ku80), MRX (Mre11/Rad50/Xrs2) and DNA ligase IV (Dnl4/Lif1). Mammalian NHEJ is more complex, primarily as a consequence of the fact that more factors are involved in the process, and also because higher chromatin organization and more complex regulatory networks exist in mammals...
December 3, 2016: Current Genetics
https://www.readbyqxmd.com/read/27914769/clinicopathological-and-molecular-characteristics-of-ku-70-80-expression-in-nigerian-breast-cancer-and-its-potential-therapeutic-implications
#18
Ayodeji O J Agboola, Henry O Ebili, Victoria O Iyawe, Adekunbiola A F Banjo, Babatunde A Salami, Emad A Rakha, Chrstopher C Nolan, Ian O Ellis, Andrew R Green
Ku 70/80 is a regulator of the Non-Homologous End Joining (NHEJ) roles in clinicopathological features, and has prognostic significance in breast cancer (BC) in Caucasian populations. However, its significance in the Nigerian BC population, which is characterized by a higher rate of the triple-negative and basal phenotype, p53 mutation rate and BRCA1 deficiency, still needs to be investigated. We hypothesize that Ku70/80 expression shows adverse expression in Nigerian BC and, furthermore, that it is likely to have a therapeutic implication for Black BC management...
January 2017: Pathology, Research and Practice
https://www.readbyqxmd.com/read/27875301/an-intrinsically-disordered-aplf-links-ku-dna-pkcs-and-xrcc4-dna-ligase-iv-in-an-extended-flexible-non-homologous-end-joining-complex
#19
Michal Hammel, Yaping Yu, Sarvan K Radhakrishnan, Chirayu Chokshi, Miaw-Sheue Tsai, Yoshihiro Matsumoto, Monica Kuzdovich, Soumya G Remesh, Shujuan Fang, Alan E Tomkinson, Susan P Lees-Miller, John A Tainer
DNA double-strand break (DSB) repair by non-homologous end joining (NHEJ) in human cells is initiated by Ku heterodimer binding to a DSB, followed by recruitment of core NHEJ factors including DNA-dependent protein kinase catalytic subunit (DNA-PKcs), XRCC4-like factor (XLF), and XRCC4 (X4)-DNA ligase IV (L4). Ku also interacts with accessory factors such as aprataxin and polynucleotide kinase/phosphatase-like factor (APLF). Yet, how these factors interact to tether, process, and ligate DSB ends while allowing regulation and chromatin interactions remains enigmatic...
December 30, 2016: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/27869163/wwox-brca1-interaction-role-in-dna-repair-pathway-choice
#20
M S Schrock, B Batar, J Lee, T Druck, B Ferguson, J H Cho, K Akakpo, H Hagrass, N A Heerema, F Xia, J D Parvin, C M Aldaz, K Huebner
In this study, loss of expression of the fragile site-encoded Wwox protein was found to contribute to radiation and cisplatin resistance of cells, responses that could be associated with cancer recurrence and poor outcome. WWOX gene deletions occur in a variety of human cancer types, and reduced Wwox protein expression can be detected early during cancer development. We found that Wwox loss is followed by mild chromosome instability in genomes of mouse embryo fibroblast cells from Wwox-knockout mice. Human and mouse cells deficient for Wwox also exhibit significantly enhanced survival of ionizing radiation and bleomycin treatment, agents that induce double-strand breaks (DSBs)...
November 21, 2016: Oncogene
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