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Buki Kwon, Palinda Ruvan Munashingha, Yong-Keol Shin, Chul-Hwan Lee, Bing Li, Yeon-Soo Seo
Highly conserved eukaryotic histones are polybasic proteins that package DNA into nucleosomes, a building block of chromatin, allowing extremely long DNA molecules to form compact and discrete chromosomes. The histone N-terminal tails that extend from the nucleosome core act as docking sites for many proteins through diverse posttranslational modifications, regulating various DNA transactions. In this report, we present evidence that the nucleosomes can positively regulate the enzymatic activity of Rad27 (yeast Fen1), a major processing enzyme important for Okazaki fragment in eukaryotes...
October 19, 2016: FEBS Journal
Z Z Liu, S T Cui, B Tang, Z Z Wang, Z X Luan
The aim of this study was to screen for key biomarkers of osteosarcoma (OS) by tracking altered modules. Protein-protein interaction (PPI) networks of OS and normal groups were constructed and re-weighted using the Pearson correlation coefficient (PCC), respectively. The condition-specific modules were explored from OS and normal PPI networks using a clique-merging algorithm. Altered modules were identified by a maximum weight bipartite-matching method. The important biological pathways in OS were identified by a pathway-enrichment analysis using genes from disrupted modules...
August 26, 2016: Genetics and Molecular Research: GMR
Maryam Rezaei, Mohammad Hashemi, Sara Sanaei, Mohammad Ali Mashhadi, Seyed Mehdi Hashemi, Gholamreza Bahari, Mohsen Taheri
Flap endonuclease 1 (FEN1), a DNA repair protein, is important in preventing carcinogenesis. Two functional germ line variants -69G>A (rs174538) and +4150G>T (rs4246215) in the FEN1 gene have been associated with risk of various types of cancer. The aim of the present study was to evaluate the possible impact of FEN1 polymorphisms on risk of breast cancer (BC) in a sample of Iranian subjects. The FEN1 -69G>A and +4150G>T polymorphisms were analyzed in a case-control study that included 266 BC patients and 225 healthy females...
October 2016: Biomedical Reports
Lina Zhou, Huifang Dai, Jian Wu, Mian Zhou, Hua Yuan, Juan Du, Lu Yang, Xiwei Wu, Hong Xu, Yuejin Hua, Jian Xu, Li Zheng, Binghui Shen
Flap endonuclease 1 (FEN1) phosphorylation is proposed to regulate the action of FEN1 in DNA repair as well as Okazaki fragment maturation. However, the biologic significance of FEN1 phosphorylation in response to DNA damage remains unknown. Here, we report an in vivo role for FEN1 phosphorylation, using a mouse line carrying S187A FEN1, which abolishes FEN1 phosphorylation. Although S187A mouse embryonic fibroblast cells showed normal proliferation under low oxygen levels (2%), the mutant cells accumulated oxidative DNA damage, activated DNA damage checkpoints, and showed G1 phase arrest at atmospheric oxygen levels (21%)...
September 30, 2016: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Shyamalagauri Jadhav, Sarah Russo, Stéphanie Cottier, Roger Schneiter, Ashley Cowart, Miriam L Greenberg
Bipolar disorder (BD), which is characterized by depression and mania, affects 1-2% of the world population. Current treatments are effective in only 40-60% of cases and cause severe side effects. Valproate (VPA) is one of the most widely used drugs for the treatment of BD, but the therapeutic mechanism of action of this drug is not understood. This knowledge gap has hampered the development of effective treatments. To identify candidate pathways affected by VPA, we performed a genome-wide expression analysis in yeast cells grown in the presence or absence of the drug...
October 14, 2016: Journal of Biological Chemistry
Jack C Exell, Mark J Thompson, L David Finger, Steven J Shaw, Judit Debreczeni, Thomas A Ward, Claire McWhirter, Catrine L B Siöberg, Daniel Martinez Molina, W Mark Abbott, Clifford D Jones, J Willem M Nissink, Stephen T Durant, Jane A Grasby
The structure-specific nuclease human flap endonuclease-1 (hFEN1) plays a key role in DNA replication and repair and may be of interest as an oncology target. We present the crystal structure of inhibitor-bound hFEN1, which shows a cyclic N-hydroxyurea bound in the active site coordinated to two magnesium ions. Three such compounds had similar IC50 values but differed subtly in mode of action. One had comparable affinity for protein and protein-substrate complex and prevented reaction by binding to active site catalytic metal ions, blocking the necessary unpairing of substrate DNA...
October 2016: Nature Chemical Biology
Kwon Joong Yong, Diane E Milenic, Kwamena E Baidoo, Martin W Brechbiel
In pre-clinical studies, combination therapy with gemcitabine and targeted radioimmunotherapy (RIT) using 212Pb-trastuzumab showed tremendous therapeutic potential in the LS-174T tumor xenograft model of disseminated intraperitoneal disease. To better understand the underlying molecular basis for the observed cell killing efficacy, gene expression profiling was performed after a 24 h exposure to 212Pb-trastuzumab upon gemcitabine (Gem) pre-treatment in this model. DNA damage response genes in tumors were quantified using a real time quantitative PCR array (qRT-PCR array) covering 84 genes...
2016: PloS One
Meng Niu, Hongshan Zhong, Haibo Shao, Duo Hong, Tengchuang Ma, Ke Xu, Xiaowei Chen, Jinhang Han, Jun Sun
Although mesoporous silica nanoparticles (MSNs) are widely used in food products, cosmetics and nanomedicines as vector for drug delivery, data on their potential genotoxocity are limited. The aim of this study was to investigate the cytotoxic and genotoxic potentials of MSNs of different shapes, and to establish a high-throughput screening method for nanoparticles. We used functional macrophage receptor with collagenous structure (MARCO)-expressing DNA repair deficient chicken DT40 cells, which are designed to internalize nanoparticles and to be deficient in several specific DNA repair pathways...
March 2016: Journal of Nanoscience and Nanotechnology
Hong Xu, Xuanyi Chen, Xiaoli Xu, Rongyi Shi, Shasha Suo, Kaiying Cheng, Zhiguo Zheng, Meixia Wang, Liangyan Wang, Ye Zhao, Bing Tian, Yuejin Hua
Lysine acetylation and succinylation are major types of protein acylation that are important in many cellular processes including gene transcription, cellular metabolism, DNA damage response. Malfunctions in these post-translational modifications are associated with genome instability and disease in higher organisms. In this study, we used high-resolution nano liquid chromatography-tandem mass spectrometry combined with affinity purification to quantify the dynamic changes of protein acetylation and succinylation in response to ultraviolet (UV)-induced cell stress...
2016: Scientific Reports
Yimei Jin, Xin Xu, Xuemeng Wang, Henry Kuang, Michael Osterman, Shi Feng, Deqiang Han, Yu Wu, Mo Li, Hongyan Guo
Ovarian cancer is one of the most common cancers among women, accounting for more deaths than any other gynecological diseases. However, the survival rate for ovarian cancer has not essentially improved over the past thirty years. Thus, to understand the molecular mechanism of ovarian tumorigenesis is important for optimizing the early diagnosis and treating this disease. In this study, we observed obvious DNA lesions, especially DNA double strand breaks (DSBs) accompanying cell cycle checkpoint activation, in the human epithelial ovarian cancer samples, which could be due to the impaired DNA response machinery...
July 6, 2016: Oncotarget
H Sun, L He, H Wu, F Pan, X Wu, J Zhao, Z Hu, C Sekhar, H Li, L Zheng, H Chen, B H Shen, Z Guo
Flap endonuclease-1 (FEN1) is a multifunctional, structure-specific nuclease that has a critical role in maintaining human genome stability. FEN1 mutations have been detected in human cancer specimens and have been suggested to cause genomic instability and cancer predisposition. However, the exact relationship between FEN1 deficiency and cancer susceptibility remains unclear. In the current work, we report a novel colorectal cancer-associated FEN1 mutation, L209P. This mutant protein lacks the FEN, exonuclease (EXO) and gap endonuclease (GEN) activities of FEN1 but retains DNA-binding affinity...
June 6, 2016: Oncogene
Jixiang Zhang, Shaojun Xie, Jian-Kang Zhu, Zhizhong Gong
As a central component in the maturation of Okazaki fragments, flap endonuclease 1 (FEN1) removes the 5'-flap and maintains genomic stability. Here, FEN1 was cloned as a suppressor of transcriptional gene silencing (TGS) from a forward genetic screen. FEN1 is abundant in the root and shoot apical meristems and FEN1-GFP shows a nucleolus-localized signal in tobacco cells. The Arabidopsis fen1-1 mutant is hypersensitive to methyl methanesulfonate and shows reduced telomere length. Interestingly, genome-wide chromatin immunoprecipitation and RNA sequencing results demonstrate that FEN1 mutation leads to a decrease in the level of H3K27me3 and an increase in the expression of a subset of genes marked with H3K27me3...
September 2016: Plant Journal: for Cell and Molecular Biology
Kailash Karthikeyan, Kristi Barker, Yanyang Tang, Peter Kahn, Peter Wiktor, Al Brunner, Vinicius Knabben, Bharath Takulapalli, Jane Buckner, Gerald Nepom, Joshua LaBaer, Ji Qiu
Aberrant modifications of proteins occur during disease development and elicit disease-specific antibody responses. We have developed a protein array platform that enables the modification of many proteins in parallel and assesses their immunogenicity without the need to express, purify, and modify proteins individually. We used anticitrullinated protein antibodies (ACPAs) in rheumatoid arthritis (RA) as a model modification and profiled antibody responses to ∼190 citrullinated proteins in 20 RA patients...
July 2016: Molecular & Cellular Proteomics: MCP
Satya Narayan, Aruna S Jaiswal, Brian K Law, Mohammad A Kamal, Arun K Sharma, Robert A Hromas
Aberrant DNA base excision repair (BER) contributes to malignant transformation. However, inter-individual variations in DNA repair capacity plays a key role in modifying breast cancer risk. We review here emerging evidence that two proteins involved in BER - adenomatous polyposis coli (APC) and flap endonuclease 1 (Fen1) - promote the development of breast cancer through novel mechanisms. APC and Fen1 expression and interaction is increased in breast tumors versus normal cells, APC interacts with and blocks Fen1 activity in Pol-β-directed LP-BER, and abrogation of LP-BER is linked with cigarette smoke condensate-induced transformation of normal breast epithelial cells...
May 2016: DNA Repair
Joseph L Stodola, Peter M Burgers
DNA polymerase delta (Pol δ) is responsible for elongation and maturation of Okazaki fragments. Pol δ and the flap endonuclease FEN1, coordinated by the PCNA clamp, remove RNA primers and produce ligatable nicks. We studied this process in the Saccharomyces cerevisiae machinery at millisecond resolution. During elongation, PCNA increased the Pol δ catalytic rate by >30-fold. When Pol δ invaded double-stranded RNA-DNA representing unmatured Okazaki fragments, the incorporation rate of each nucleotide decreased successively to 10-20% that of the preceding nucleotide...
May 2016: Nature Structural & Molecular Biology
Sai Ba, Hao Zhang, Jasmine Yiqin Lee, Haixia Wu, Ruijuan Ye, Dejian Huang, Tianhu Li
Flap structure-specific endonuclease 1 (FEN1) is one of the enzymes that involve in Eukaryotic DNA replication and repair. Recent studies have proved that FEN1 is highly over-expressed in various types of cancer cells and is a drug target. However, a limited number of FEN1 inhibitors has been identified and approved. Herein, we investigate the catalytic activity of FEN1, and propose a substrate-based inhibitor. As a consequence, one of the phosphorothioate-modified substrates is proved to exhibit the most efficient inhibitory effect in our in vitro examinations...
May 1, 2016: Bioorganic & Medicinal Chemistry
Jusciele B Moreli, Janine H Santos, Aline Rodrigues Lorenzon-Ojea, Simone Corrêa-Silva, Rodrigo S Fortunato, Clarissa Ribeiro Rocha, Marilza V Rudge, Débora C Damasceno, Estela Bevilacqua, Iracema M Calderon
OBJECTIVE: Investigate the DNA damage and its cellular response in blood samples from both mother and the umbilical cord of pregnancies complicated by hyperglycemia. METHODS: A total of 144 subjects were divided into 4 groups: normoglycemia (ND; 46 cases), mild gestational hyperglycemia (MGH; 30 cases), gestational diabetes mellitus (GDM; 45 cases) and type-2 diabetes mellitus (DM2; 23 cases). Peripheral blood mononuclear cell (PBMC) isolation and/or leukocytes from whole maternal and umbilical cord blood were obtained from all groups at delivery...
2016: International Journal of Biological Sciences
Dominik Kwiatkowski, Piotr Czarny, Monika Toma, Anna Korycinska, Katarzyna Sowinska, Piotr Galecki, Agnieszka Bachurska, Anna Bielecka-Kowalska, Janusz Szemraj, Michael Maes, Tomasz Sliwinski
BACKGROUND: One of the factors that contribute to Alzheimer's disease (AD) is the DNA damage caused by oxidative stress and inflammation that occurs in nerve cells. It has been suggested that the risk of AD may be associated with an age-dependent reduction of the DNA repair efficiency. Base excision repair (BER) is, among other things, a main repair system of oxidative DNA damage. One of the reasons for the reduced efficiency of this system may be single-nucleotide polymorphisms (SNP) of the genes encoding its proteins...
2016: Neuropsychobiology
Stuart A MacNeill
Sliding clamps play an essential role in coordinating protein activity in DNA metabolism in all three domains of life. In eukaryotes and archaea, the sliding clamp is PCNA (proliferating cell nuclear antigen). Across the diversity of the archaea PCNA interacts with a highly conserved set of proteins with key roles in DNA replication and repair, including DNA polymerases B and D, replication factor C, the Fen1 nuclease and RNAseH2, but this core set of factors is likely to represent a fraction of the PCNA interactome only...
August 2016: Current Genetics
Sana I Algasaier, Jack C Exell, Ian A Bennet, Mark J Thompson, Victoria J B Gotham, Steven J Shaw, Timothy D Craggs, L David Finger, Jane A Grasby
Human flap endonuclease-1 (hFEN1) catalyzes the essential removal of single-stranded flaps arising at DNA junctions during replication and repair processes. hFEN1 biological function must be precisely controlled, and consequently, the protein relies on a combination of protein and substrate conformational changes as a prerequisite for reaction. These include substrate bending at the duplex-duplex junction and transfer of unpaired reacting duplex end into the active site. When present, 5'-flaps are thought to thread under the helical cap, limiting reaction to flaps with free 5'-terminiin vivo Here we monitored DNA bending by FRET and DNA unpairing using 2-aminopurine exciton pair CD to determine the DNA and protein requirements for these substrate conformational changes...
April 8, 2016: Journal of Biological Chemistry
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