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DNA damage repair

Bryan A Johnson, Heather L Aloor, Cary A Moody
Human papillomaviruses (HPV) exhibit constitutive activation of ATM and ATR DNA damage response (DDR) pathways, which are required for productive viral replication. Expression of HPV31 E7 alone is sufficient to activate the DDR through an unknown mechanism. Here, we demonstrate that the E7 Rb binding domain is required to increase levels of many DDR proteins, including ATM, Chk2, Chk1, the MRN components MRE11, Rad50, and NBS1, as well as the homologous recombination repair proteins BRCA1 and Rad51. Interestingly, we have found that the increase in these DNA repair proteins does not occur solely at the level of transcription, but that E7 broadly increases the half-life of these DDR factors, a phenotype that is lost in the E7 Rb binding mutant...
October 19, 2016: Virology
Andriy Bilichak, Igor Kovalchuk
DNA strand breaks arise from normal cellular processes such as replication, transcription, and DNA repair as well as spontaneous DNA damage caused by cell metabolic activities. In addition, strand breaks occur due to direct or indirect DNA damage produced by various abiotic and biotic stresses. Strand breaks are among the most problematic DNA lesions because unrepaired strand breaks may lead to cell cycle arrest, gross chromosome rearrangements, or even cell death. Thus, the measurement of the relative number of strand breaks can provide an informative picture of genome stability of a given cell, tissue, or organism...
2017: Methods in Molecular Biology
Magdalena Szejk, Tomasz Poplawski, Joanna Sarnik, Izabela Pawlaczyk-Graja, Franciszek Czechowski, Alicja Klaudia Olejnik, Roman Gancarz, Halina Malgorzata Zbikowska
Radioprotective effects of the water-soluble polyphenolic glycoconjugates, isolated from flowers of Sanguisorba officinalis L.(SO) and Erigeron canadensis L.(EC), and from leaves of Fragaria vesca L. (FV) and Rubus plicatus Whe. Et N. E. (RP), against γ-radiation-induced toxicity in human peripheral blood lymphocytes were investigated. Cell treatment with glycoconjugates (1, 5, 25μg/ml) prior exposure to 10/15Gy radiation resulted in concentration-dependent reduction of DNA damage including oxidative DNA lesions (comet assay), substantial inhibition of lipid peroxidation (TBARS) and restoration of superoxide dismutase and S-glutathione transferase activities...
October 18, 2016: International Journal of Biological Macromolecules
Ranjan Basak, Naveen Kumar Nair, Indraneel Mittra
There is extensive literature to show that nucleic acids can be taken up by cells under experimental conditions and that foetal DNA can be detected in maternal tissues. The uptaken DNA can integrate into host cell genomes and can be transcribed and translated into proteins. They can also cause chromosomal damage and karyotype alterations. Cell-free nucleic acids (cfNAs)-based non-invasive DNA diagnostic techniques are being extensively researched in the field of cancer with the potential to advance new prognostic parameters and direct treatment decisions...
October 12, 2016: Mutation Research
Hajime Suzuki, Takahiro Sakabe, Yuu Hirose, Toshihiko Eki
We aimed to develop the bioassays for genotixicity and/or oxidative damage using the recombinant yeast. A genotoxicity assay was developed using recombinant Saccharomyces cerevisiae strain BY4741 with a green fluorescent protein (GFP) reporter plasmid, driven by the DNA damage-responsive RNR3 promoter. Enhanced fluorescence induction was observed in DNA repair-deficient strains treated with methyl methanesulfonate, but not with hydrogen peroxide. A GFP reporter yeast strain driven by the oxidative stress-responsive TRX2 promoter was newly developed to assess oxidative damage, but fluorescence was poorly induced by oxidants...
October 21, 2016: Applied Microbiology and Biotechnology
Oihane Irazoki, Jesús Aranda, Timo Zimmermann, Susana Campoy, Jordi Barbé
In addition to its role in DNA damage repair and recombination, the RecA protein, through its interaction with CheW, is involved in swarming motility, a form of flagella-dependent movement across surfaces. In order to better understand how SOS response modulates swarming, in this work the location of RecA and CheW proteins within the swarming cells has been studied by using super-resolution microscopy. Further, and after in silico docking studies, the specific RecA and CheW regions associated with the RecA-CheW interaction have also been confirmed by site-directed mutagenesis and immunoprecipitation techniques...
2016: Frontiers in Microbiology
Rui Zhang, Chang Liu, Yahan Niu, Ying Jing, Haiyang Zhang, Jin Wang, Jie Yang, Ke Zen, Junfeng Zhang, Chen-Yu Zhang, Donghai Li
The DNA damage response is critical for maintaining genome integrity and preventing damage to DNA due to endogenous and exogenous insults. Mitomycin C (MMC), a potent DNA cross-linker, is used as a chemotherapeutic agent because it causes DNA inter-strand cross-links (DNA ICLs) in cancer cells. While many microRNAs, which may serve as oncogenes or tumor suppressors, are grossly dysregulated in human cancers, little is known about their roles in MMC-treated lung cancer. Here, we report that miR-128-3p can attenuate repair of DNA ICLs by targeting SPTAN1 (αII Sp), resulting in cell cycle arrest and promoting chromosomal aberrations in lung cancer cells treated with MMC...
September 28, 2016: Oncotarget
Eun Ho Kim, Mi-Sook Kim, Kyung-Hee Lee, Jae-Soo Koh, Won-Gyun Jung, Chang-Bae Kong
To overcome radioresistance in the treatment of osteosarcoma, a primary malignant tumor of the bone, radiotherapy is generally combined with radiosensitizers. The purpose of this study was to investigate a third-generation bisphosphonate, zoledronic acid (ZOL), as a radiosensitizer for osteosarcoma. We found that exposure of KHOS/NP osteosarcoma cells to 20 μM ZOL decreased the γ-radiation dose needed to kill 90% of cells. This radiosensitizing effect of ZOL was mediated through decreased mitochondrial membrane potential, increased levels of reactive oxygen species, increased DNA damage (as assessed by counting γ-H2AX foci), decreased abundance of proteins involved in DNA repair pathways (ATR, Rad52, and DNA-PKcs), and decreased phosphorylation of PI3K-Akt and MAPK pathway proteins (Raf1, MEK1/2, ERK1/2, and Akt), as compared to γ-irradiation alone...
September 27, 2016: Oncotarget
H N Lynch, C T Loftus, J M Cohen, L E Kerper, E M Kennedy, J E Goodman
Research suggests that exposure to ambient particulate matter (PM) may be associated with lung cancer; however, no mode of action (MoA) for this has been established. We applied a weight-of-evidence (WoE) approach to evaluate recent evidence from four realms of research (controlled human exposure, epidemiology, animal, and in vitro) to determine whether the overall evidence supports one or more MoAs by which PM could cause lung cancer. We evaluated three general MoAs: DNA damage and repair; other genotoxic effects, including mutagenicity and clastogenicity; and gene expression, protein expression, and DNA methylation...
October 17, 2016: Regulatory Toxicology and Pharmacology: RTP
Kaijun Di, Naomi Lomeli, Spencer D Wood, Christopher D Vanderwal, Daniela A Bota
Mitochondrial dysfunction is a hallmark of cancer biology. Tumor mitochondrial metabolism is characterized by an abnormal ability to function in scarce oxygen conditions through glycolysis (the Warburg effect), and accumulation of mitochondrial DNA defects are present in both hereditary neoplasia and sporadic cancers. Mitochondrial Lon is a major regulator of mitochondrial metabolism and the mitochondrial response to free radical damage, and plays an essential role in the maintenance and repair of mitochondrial DNA...
October 15, 2016: Oncotarget
H Jęśko, R P Strosznajder
Sirtuins (SIRT1 to -7) are unique histone deacetylases (HDACs) whose activity depends on NAD+, thus making them capable of sensing the cellular metabolic status. Sirtuins orchestrate the stress response and damage repair, and are able to modulate the course of ageing and neurodegenerative diseases. Despite their classification as HDACs, sirtuins deacetylate a vast number of targets in many cellular compartments, and some display additional enzymatic activities including mono(ADP-ribosyl)ation. SIRTs interact with multiple signalling proteins, transcription factors and enzymes including p53, FOXOs (forkhead box subgroup O), PPARs (peroxisome proliferator-activated receptors), NF-B, and DNA-PK (DNA-dependent protein kinase)...
2016: Folia Neuropathologica
Wei He, Peng Huang, Dinghua Liu, Lingling Zhong, Rongbin Yu, Jianan Li
Background: Base excision repair (BER) is the primary DNA repair system with the ability to fix base lesions caused by oxidative damage. Genetic variants influencing the BER pathway may affect the susceptibility and the outcomes of ischemic stroke. Here, we examined how single nucleotide polymorphisms (SNPs) associated with BER impact susceptibility and short-term recovery of ischemic stroke. Methods: We selected 320 ischemic stroke patients and 303 controls. Then we genotyped SNPs of NEIL1 rs4462560, NEIL3 rs12645561 and XRCC1 rs25487 in both groups...
October 17, 2016: International Journal of Environmental Research and Public Health
Zhong Liu, Cheng Zhang, Alireza Khodadadi-Jamayran, Lam Dang, Xiaosi Han, Kitai Kim, Hu Li, Rui Zhao
Neural stem cells (NSCs) have the capacity to differentiate into neurons, astrocytes, and oligodendrocytes, and therefore represent a promising donor tissue source for treating neurodegenerative diseases and repairing injuries of the nervous system. However, it remains unclear how canonical microRNAs (miRNAs), the subset of miRNAs requiring the Drosha-Dgcr8 microprocessor and the type III RNase Dicer for biogenesis, regulate NSCs. In this study, we established and characterized <i>Dgcr8</i><sup>-/-</sup> NSCs from conditionally <i>Dgcr8</i>-disrupted mouse embryonic brain...
October 20, 2016: Stem Cells and Development
Teodora Nikolova, Anja Göder, Ann Parplys, Kerstin Borgmann
DNA fiber spreading assay is an invaluable technique to visualize and follow the spatial and temporal progress of individual DNA replication forks. It provides information on the DNA replication progress and its regulation under normal conditions as well as on replication stress induced by environmental genotoxic agents or cancer drugs. The method relies on the detection of incorporated thymidine analogues during DNA synthesis in the S phase of the cell cycle by indirect immunofluorescence. Here, we describe the procedure established in our laboratories for sequential pulse labeling of human cells with 5-chloro-2'-deoxyuridine (CldU) and 5-iodo-2'-deoxyuridine (IdU), cell lysis, and DNA fiber spreading on slides and sequential immunodetection of the incorporated thymidine analogues by primary antibodies recognizing specifically CldU or IdU alone...
2017: Methods in Molecular Biology
Nicholas E Mamrak, Akiko Shimamura, Niall G Howlett
Fanconi anemia (FA) is a rare autosomal and X-linked genetic disease characterized by congenital abnormalities, progressive bone marrow failure (BMF), and increased cancer risk during early adulthood. The median lifespan for FA patients is approximately 33years. The proteins encoded by the FA genes function together in the FA-BRCA pathway to repair DNA damage and to maintain genome stability. Within the past two years, five new FA genes have been identified-RAD51/FANCR, BRCA1/FANCS, UBE2T/FANCT, XRCC2/FANCU, and REV7/FANCV-bringing the total number of disease-causing genes to 21...
October 13, 2016: Blood Reviews
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
Mohammad B Hossain, Rehnuma Shifat, David G Johnson, Mark T Bedford, Konrad R Gabrusiewicz, Nahir Cortes-Santiago, Xuemei Luo, Zhimin Lu, Ravesanker Ezhilarasan, Erik P Sulman, Hong Jiang, Shawn S C Li, Frederick F Lang, Jessica Tyler, Mien-Chie Hung, Juan Fueyo, Candelaria Gomez-Manzano
DNA repair pathways enable cancer cells to survive DNA damage induced after genotoxic therapies. Tyrosine kinase receptors (TKRs) have been reported as regulators of the DNA repair machinery. TIE2 is a TKR overexpressed in human gliomas at levels that correlate with the degree of increasing malignancy. Following ionizing radiation, TIE2 translocates to the nucleus, conferring cells with an enhanced nonhomologous end-joining mechanism of DNA repair that results in a radioresistant phenotype. Nuclear TIE2 binds to key components of DNA repair and phosphorylates H4 at tyrosine 51, which, in turn, is recognized by the proto-oncogene ABL1, indicating a role for nuclear TIE2 as a sensor for genotoxic stress by action as a histone modifier...
April 2016: Science Advances
Vibhuti Joshi, Ayeman Amanullah, Arun Upadhyay, Ribhav Mishra, Amit Kumar, Amit Mishra
Cells regularly synthesize new proteins to replace old and abnormal proteins for normal cellular functions. Two significant protein quality control pathways inside the cellular milieu are ubiquitin proteasome system (UPS) and autophagy. Autophagy is known for bulk clearance of cytoplasmic aggregated proteins, whereas the specificity of protein degradation by UPS comes from E3 ubiquitin ligases. Few E3 ubiquitin ligases, like C-terminus of Hsc70-interacting protein (CHIP) not only take part in protein quality control pathways, but also plays a key regulatory role in other cellular processes like signaling, development, DNA damage repair, immunity and aging...
2016: Frontiers in Molecular Neuroscience
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
Daniela Pelclova, Vladimir Zdimal, Petr Kacer, Martin Komarc, Zdenka Fenclova, Stepanka Vlckova, Nadezda Zikova, Jaroslav Schwarz, Otakar Makes, Tomas Navratil, Sergey Zakharov, Dhimiter Bello
Nanoscale titanium dioxide (nanoTiO2) is a commercially important nanomaterial used in numerous applications. Experimental studies with nanotitania have documented lung injury and inflammation, oxidative stress, and genotoxicity. Production workers in TiO2 manufacturing with a high proportion of nanoparticles and a mixture of other air pollutants, such as gases and organic aerosols, had increased markers of oxidative stress, including DNA and protein damage, as well as lipid peroxidation in their exhaled breath condensate (EBC) compared to unexposed controls...
October 18, 2016: Reviews on Environmental Health
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