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Neha J Pancholi, Matthew D Weitzman
During viral replication in the nucleus, the DNA genomes of adenoviruses are accessible to cellular DNA-binding proteins. Human adenovirus type 5 (Ad5) targets the cellular Mre11-Rad50-Nbs1 complex (MRN) to evade detection by the DNA damage response (DDR). Ad5 mutants that cannot target MRN have reduced viral propagation. Previous studies showed that diverse adenovirus serotypes interact differently with MRN. While these studies revealed diverse MRN interactions among serotypes, it remains unclear how these differences influence viral replication...
March 13, 2018: Virology
Chunwei Ye, Yi Cai, Qian Cai, Shunhui Yuan, Fan Huang, Xiaofang Yang, Shuchen He, Zhuoheng Li, Yanwen Wang, Delin Yang, Zhipeng Li
The aim of the present study was to investigate the candidate genes and pathways associated with benign prostatic hyperplasia (BPH) and diabetes. In vitro experiments were performed using normal prostatic epithelial RWPE‑1 and HPr‑1 cells. The cell lines were treated with a high‑glucose solution and MTS and bromodeoxyuridine assays were used to assess cell viability. Transcriptome sequencing was used to screen the candidate genes. The expression of candidate genes was further verified by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blotting...
March 7, 2018: International Journal of Molecular Medicine
Dehong Huang, Lei Jin, Zhengkang Li, Ji Wu, Ni Zhang, Dianrong Zhou, Xiaorong Ni, Tieying Hou
Hepatoblastoma (HB) is the most common malignant liver tumor in children. DNA and DNA-associated processes are one of the most important targets of chemotherapeutic agents. Isoorientin (Iso), a natural flavonoid compound, can be extracted from several plant species. The effects of Iso and its molecular mechanisms on hepatic malignancies remain unclear. Herein, the anti-tumor effects of Iso in HB and its underlying mechanisms were explored. We found that Iso significantly inhibited the proliferation of HB cells both in vitro and in vivo...
March 7, 2018: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
Vivek Tripathi, Himanshi Agarwal, Swati Priya, Harish Batra, Priyanka Modi, Monica Pandey, Dhurjhoti Saha, Sathees C Raghavan, Sagar Sengupta
Mutations in BLM in Bloom Syndrome patients predispose them to multiple types of cancers. Here we report that BLM is recruited in a biphasic manner to annotated DSBs. BLM recruitment is dependent on the presence of NBS1, MRE11 and ATM. While ATM activity is essential for BLM recruitment in early phase, it is dispensable in late phase when MRE11 exonuclease activity and RNF8-mediated ubiquitylation of BLM are the key determinants. Interaction between polyubiquitylated BLM and NBS1 is essential for the helicase to be retained at the DSBs...
March 9, 2018: Nature Communications
Davide Moiani, Daryl A Ronato, Chris A Brosey, Andrew S Arvai, Aleem Syed, Jean-Yves Masson, Elena Petricci, John A Tainer
For inhibitor design, as in most research, the best system is question dependent. We suggest structurally defined allostery to design specific inhibitors that target regions beyond active sites. We choose systems allowing efficient quality structures with conformational changes as optimal for structure-based design to optimize inhibitors. We maintain that evolutionarily related targets logically provide molecular avatars, where this Sanskrit term for descent includes ideas of functional relationships and of being a physical embodiment of the target's essential features without requiring high sequence identity...
2018: Methods in Enzymology
Enrico Mini, Ida Landini, Laura Lucarini, Andrea Lapucci, Cristina Napoli, Gabriele Perrone, Renato Tassi, Emanuela Masini, Flavio Moroni, Stefania Nobili
The poly(ADP-ribose) polymerase (PARP) enzymes play a key role in the regulation of cellular processes (e.g., DNA damage repair, genomic stability). It has been shown that PARP inhibitors (PARPIs) are selectively cytotoxic against cells having dysfunctions in genes involved in DNA repair mechanisms (synthetic lethality). Drug-induced PARP inhibition potentiates the activity of anticancer drugs such as 5-fluorouracil in enhancing DNA damage, whose repair involves PARP-1 activity. The aim of this study was to evaluate the inhibitory effects of a novel PARPI, HYDAMTIQ, on growth in human tumor cell lines characterized by different features with regard to DNA damage response pathways (BRCA mutational status, microsatellite status, and ATM expression level) and degree of sensitivity/resistance to 5-fluorouracil...
March 5, 2018: Oncology Research
Joung-Sun Park, Ho-Jun Jeon, Jung-Hoon Pyo, Young-Shin Kim, Mi-Ae Yoo
Stem cell dysfunction is closely linked to tissue and organismal aging and age-related diseases, and heavily influenced by the niche cells' environment. The DNA damage response (DDR) is a key pathway for tissue degeneration and organismal aging; however, the precise protective role of DDR in stem cell/niche aging is unclear. The Drosophila midgut is an excellent model to study the biology of stem cell/niche aging because of its easy genetic manipulation and its short lifespan. Here, we showed that deficiency of DDR in Drosophila enterocytes (ECs) accelerates intestinal stem cell (ISC) aging...
March 7, 2018: Aging
Charlene H Emerson, Christopher R Lopez, Albert Ribes-Zamora, Erica J Polleys, Christopher L Williams, Lythou Yeo, Jacques E Zaneveld, Rui Chen, Alison A Bertuch
The Ku heterodimer acts centrally in non-homologous end-joining (NHEJ) of DNA double strand breaks (DSB). Saccharomyces cerevisiae Ku, like mammalian Ku, binds and recruits NHEJ factors to DSB ends. Consequently, NHEJ is virtually absent in yeast Ku null ( yku 70Δ or yku80Δ ) strains. Previously, we unexpectedly observed imprecise NHEJ proficiency in a yeast Ku mutant with impaired DNA end-binding (DEB). However, how DEB impairment supported imprecise NHEJ was unknown. Here, we found imprecise NHEJ proficiency to be a feature of a panel of DEB-impaired Ku mutants and that DEB impairment resulted in a deficiency in precise NHEJ...
March 2, 2018: Genetics
Mariarosaria De Falco, Federica Massa, Mosè Rossi, Mariarita De Felice
ATPase/Helicases and nucleases play important roles in DNA end-resection, a critical step during homologous recombination repair in all organisms. In hyperthermophilic archaea the exo-endonuclease NurA and the ATPase HerA cooperate with the highly conserved Mre11-Rad50 complex in 3' single-stranded DNA (ssDNA) end processing to coordinate repair of double-stranded DNA breaks. Little is known, however, about the assembly mechanism and activation of the HerA-NurA complex. In this study we demonstrate that the NurA exonuclease activity is inhibited by the Sulfolobus solfataricus RecQ-like Hel112 helicase...
February 27, 2018: Extremophiles: Life Under Extreme Conditions
Valentine Mosbach, Lucie Poggi, David Viterbo, Marine Charpentier, Guy-Franck Richard
Trinucleotide repeat expansions involving CTG/CAG triplets are responsible for several neurodegenerative disorders, including myotonic dystrophy and Huntington's disease. Because expansions trigger the disease, contracting repeat length could be a possible approach to gene therapy for these disorders. Here, we show that a TALEN-induced double-strand break was very efficient at contracting expanded CTG repeats in yeast. We show that RAD51, POL32, and DNL4 are dispensable for double-strand break repair within CTG repeats, the only required genes being RAD50, SAE2, and RAD52...
February 20, 2018: Cell Reports
Cosimo Pinto, Roopesh Anand, Petr Cejka
DNA end resection initiates the largely accurate repair of DNA double-strand breaks (DSBs) by homologous recombination. Specifically, recombination requires the formation of 3' overhangs at DSB sites, which is carried out by nucleases that specifically degrade 5'-terminated DNA. In most cases, DNA end resection is a two-step process, comprising of initial short-range followed by more processive long-range resection. In this chapter, we describe selected assays that reconstitute both the short- and long-range pathways...
2018: Methods in Enzymology
Roopesh Anand, Cosimo Pinto, Petr Cejka
Accurate repair of DNA double-strand breaks (DSBs) is carried out by homologous recombination. In order to repair DNA breaks by the recombination pathway, the 5'-terminated DNA strand at DSB sites must be first nucleolytically processed to produce 3'-overhang. The process is termed DNA end resection and involves the interplay of several nuclease complexes. DNA end resection commits DSB repair to the recombination pathway including a process termed single-strand annealing, as resected DNA ends are generally nonligatable by the competing nonhomologous end-joining machinery...
2018: Methods in Enzymology
Tibebe A Teklemariam, Osvaldo D Rivera, Scott W Nelson
Bacteriophage T4 encodes orthologs of the proteins Rad50 (gp46) and Mre11 (gp47), which form a heterotetrameric complex (MR) that is responsible for host genome degradation and the processing of DNA ends for recombination-dependent DNA repair. In this chapter, we describe the ensemble methods currently employed by our laboratory to characterize the exonuclease activity of the T4 MR complex. DNA exonucleases play a vital role in maintaining the integrity of DNA through their participation in DNA repair pathways and as proofreaders for DNA polymerases...
2018: Methods in Enzymology
Terri G Edwards, Chris Fisher
The ability of antiviral polyamides (AVP) to act upon polyomaviruses (PyV) was evaluated. Initial studies found that a single treatment of AVP protected SV40-infected BSC-1 cells from cytopathic effect (CPE) for as long as 11 days p.i.. AVP substantially suppressed SV40 genome copy numbers over the duration of the experiment. Immunofluorescence analysis of ataxia-telangiectasia mutated (ATM) activation and large T antigen (LTag) expression clearly demonstrated that AVP treatment at day 1 p.i. delayed the onset of productive SV40 replication by approximately 3 days, and substantially limited the infection relative to vehicle-treated controls...
February 16, 2018: Antiviral Research
Raneem Habib, Heidemarie Neitzel, Aurelie Ernst, John K L Wong, Bozenna Goryluk-Kozakiewicz, Antje Gerlach, Ilja Demuth, Karl Sperling, Krystyna Chrzanowska
Background: Nijmegen breakage syndrome is an autosomal recessive disorder characterized by microcephaly, immunodeficiency, hypersensitivity to X-irradiation, and a high predisposition to cancer. Nibrin, the product of the NBN gene, is part of the MRE11/RAD50 (MRN) complex that is involved in the repair of DNA double strand breaks (DSBs), and plays a critical role in the processing of DSBs in immune gene rearrangements, telomere maintenance, and meiotic recombination. NBS skin fibroblasts grow slowly in culture and enter early into senescence...
2018: Molecular Cytogenetics
Sangita Pal, Spike D Postnikoff, Myrriah Chavez, Jessica K Tyler
The causal relationship between genomic instability and replicative aging is unclear. We reveal here that genomic instability at the budding yeast ribosomal DNA (rDNA) locus increases during aging, potentially due to the reduced cohesion that we uncovered during aging caused by the reduced abundance of multiple cohesin subunits, promoting increased global chromosomal instability. In agreement, cohesion is lost during aging at other chromosomal locations in addition to the rDNA, including centromeres. The genomic instability in old cells is exacerbated by a defect in DNA double-strand break (DSB) repair that we uncovered in old yeast...
February 2018: Science Advances
Brenda R Lemos, Adam C Kaplan, Ji Eun Bae, Alexander E Ferrazzoli, James Kuo, Ranjith P Anand, David P Waterman, James E Haber
Harnessing CRISPR-Cas9 technology provides an unprecedented ability to modify genomic loci via DNA double-strand break (DSB) induction and repair. We analyzed nonhomologous end-joining (NHEJ) repair induced by Cas9 in budding yeast and found that the orientation of binding of Cas9 and its guide RNA (gRNA) profoundly influences the pattern of insertion/deletions (indels) at the site of cleavage. A common indel created by Cas9 is a 1-bp (+1) insertion that appears to result from Cas9 creating a 1-nt 5' overhang that is filled in by a DNA polymerase and ligated...
February 13, 2018: Proceedings of the National Academy of Sciences of the United States of America
Jung-Kuei Chen, Wen-Ling Lin, Zhang Chen, Hung-Wen Liu
Maintenance of genome integrity is critical for both faithful propagation of genetic information and prevention of mutagenesis induced by various DNA damage events. Here we report cold-inducible RNA-binding protein (CIRBP) as a newly identified key regulator in DNA double-strand break (DSB) repair. On DNA damage, CIRBP temporarily accumulates at the damaged regions and is poly(ADP ribosyl)ated by poly(ADP ribose) polymerase-1 (PARP-1). Its dissociation from the sites of damage may depend on its phosphorylation status as mediated by phosphatidylinositol 3-kinase-related kinases...
February 20, 2018: Proceedings of the National Academy of Sciences of the United States of America
Corinne Cassani, Elisa Gobbini, Jacopo Vertemara, Weibin Wang, Antonio Marsella, Patrick Sung, Renata Tisi, Giuseppe Zampella, Maria Pia Longhese
Sae2 cooperates with the Mre11-Rad50-Xrs2 (MRX) complex to initiate resection of DNA double-strand breaks (DSBs) and to maintain the DSB ends in close proximity to allow their repair. How these diverse MRX-Sae2 functions contribute to DNA damage resistance is not known. Here, we describe mre11 alleles that suppress the hypersensitivity of sae2Δ cells to genotoxic agents. By assessing the impact of these mutations at the cellular and structural levels, we found that all the mre11 alleles that restore sae2Δ resistance to both camptothecin and phleomycin affect the Mre11 N-terminus and suppress the resection defect of sae2Δ cells by lowering MRX and Tel1 association to DSBs...
February 6, 2018: Nucleic Acids Research
Anjali Shailani, Raman Preet Kaur, Anjana Munshi
BRCA2is the main susceptibility gene known to be involved in the pathogenesis of breast cancer. It plays an important role in maintaining the genome stability by homologous recombination through DNA double-strand breaks repairing, by interacting with various other proteins including RAD51, DSS1, RPA, MRE11, PALB2, and p53. BRCA2-deficient cells show the abnormalities of chromosome number. BRCA2 is also found to be involved in centrosome duplication specifically in the metaphase to anaphase transition. Inactivation or depletion of BRCA2 leads to centrosome amplification that results in unequal separation of chromosomes...
January 31, 2018: Medical Oncology
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