Read by QxMD icon Read


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
R C Yan, J Wang, Z Z Huang, Z Y Wang, X F Wu, J C Huang, L H Chang, D Q Li, G H Zhang
Objective: To investigate the killing effects of radiation and mutant Rad50 transfection on human nasopharyngeal carcinoma cell line CNE1. Methods: The experimental groups included: control group, Ad-Rad50-GFP group, Ad-EGFP group, irradiation group, Ad-Rad50-GFP combined with irradiation group, and Ad-EGFP combined with irradiation group. CNE1 cells were transfected with recombinant adenoviral vector Ad-Rad50-GFP carrying mutant Rad50 gene. The expressions of Mre11, Rad50, Nbs1, and relevant constituents composing MRN complex were detected by Western Blot...
October 7, 2016: Zhonghua Er Bi Yan Hou Tou Jing Wai Ke za Zhi, Chinese Journal of Otorhinolaryngology Head and Neck Surgery
Maurizio Cirilli, Oxana Bereshchenko, Olga Ermakova, Claus Nerlov
BACKGROUND: C/EBPa and C/EBPb are transcription factors with tissue specific expression regulating several important cellular processes. They work by recruiting protein complexes to a common DNA recognition motif and both are able to compensate each other's absence in many cell types, thus showing functional redundancy. They also play distinct roles in specific cellular pathways and their abnormal functioning gives raise to different human pathologies. METHODS: To investigate the molecular basis of C/EBPa and C/EBPb specificity and redundancy we characterized their in vivo protein-protein interaction networks by Tandem Affinity Purification and Mass Spectrometry...
October 13, 2016: Biochimica et Biophysica Acta
Julyun Oh, Amr Al-Zain, Elda Cannavo, Petr Cejka, Lorraine S Symington
The Mre11-Rad50-Xrs2/Nbs1 (MRX/N) complex orchestrates the cellular response to DSBs through its structural, enzymatic, and signaling roles. Xrs2/Nbs1 is essential for nuclear translocation of Mre11, but its role as a component of the complex is not well defined. Here, we demonstrate that nuclear localization of Mre11 (Mre11-NLS) is able to bypass several functions of Xrs2, including DNA end resection, meiosis, hairpin resolution, and cellular resistance to clastogens. Using purified components, we show that the MR complex has equivalent activity to MRX in cleavage of protein-blocked DNA ends...
October 20, 2016: Molecular Cell
Arun Kanakkanthara, Karthik B Jeganathan, Jazeel F Limzerwala, Darren J Baker, Masakazu Hamada, Hyun-Ja Nam, Willemijn H van Deursen, Naomi Hamada, Ryan M Naylor, Nicole A Becker, Brian A Davies, Janine H van Ree, Georges Mer, Virginia S Shapiro, L James Maher, David J Katzmann, Jan M van Deursen
Cyclin A2 activates the cyclin-dependent kinases Cdk1 and Cdk2 and is expressed at elevated levels from S phase until early mitosis. We found that mutant mice that cannot elevate cyclin A2 are chromosomally unstable and tumor-prone. Underlying the chromosomal instability is a failure to up-regulate the meiotic recombination 11 (Mre11) nuclease in S phase, which leads to impaired resolution of stalled replication forks, insufficient repair of double-stranded DNA breaks, and improper segregation of sister chromosomes...
September 30, 2016: Science
José Carlos Páez-Franco, Ignacio González-Sánchez, Nora A Gutiérrez-Nájera, Lilián G Valencia-Turcotte, Alfonso Lira-Rocha, Marco A Cerbón, Rogelio Rodríguez-Sotres
9-[(3-chloro)phenylamine]-2-[3-(diethylamine)propylamine]thiazolo[5,4-b]quinolone (D3ClP) is a bioisostere of N-(4-(acridin-9-ylamino)-3-methoxyphenyl)methanesulfonamide (m-AMSA) a DNA topoisomerase II inhibitor with proven cytotoxic activity and known to induce DNA damage and apoptotic cell death in K562 cells. However, recent evidence is not consistent with DNA topoisomerase II (DNA TOP2) as the primary target of D3ClP, in contrast to m-AMSA. We provide evidence of histone γH2AX phosphorylation at Ser135 in HeLa cells treated with D3ClP, a marker of DNA double strand repair through Mre11-Rad50-Nbs1 (MRN) pathway...
September 29, 2016: Journal of Cellular Biochemistry
G P Gupta, A Y Ho, W Feng, C Fan, M Akram, E Brogi, S N Powell, C M Perou, Y H Wen, J H J Petrini
No abstract text is available yet for this article.
October 1, 2016: International Journal of Radiation Oncology, Biology, Physics
Sameera Nallanthighal, Amit B Shirode, Julius A Judd, Ramune Reliene
Ionizing radiation (IR) is a well-documented human carcinogen. The increased use of IR in medical procedures has doubled the annual radiation dose and may increase cancer risk. Genomic instability is an intermediate lesion in IR-induced cancer. We examined whether pomegranate extract (PE) suppresses genomic instability induced by x-rays. Mice were treated orally with PE and exposed to an x-ray dose of 2 Gy. PE intake suppressed x-ray-induced DNA double-strand breaks (DSBs) in peripheral blood and chromosomal damage in bone marrow...
September 27, 2016: Nutrition and Cancer
Tomas Aparicio, Jean Gautier
DNA termini at double-strand breaks are often chemically heterogeneous and require processing before initiation of repair. In a recent report, we demonstrated that CtIP and the MRE11-RAD50-NBS1 (MRN) nuclease complex cooperate with BRCA1 to specifically repair topoisomerase II-DNA adducted breaks. In contrast, BRCA1 is dispensable for repair of restriction endonuclease-generated double-strand breaks.
July 2016: Molecular & Cellular Oncology
Yves Pommier, Yilun Sun, Shar-Yin N Huang, John L Nitiss
Topoisomerases introduce transient DNA breaks to relax supercoiled DNA, remove catenanes and enable chromosome segregation. Human cells encode six topoisomerases (TOP1, TOP1mt, TOP2α, TOP2β, TOP3α and TOP3β), which act on a broad range of DNA and RNA substrates at the nuclear and mitochondrial genomes. Their catalytic intermediates, the topoisomerase cleavage complexes (TOPcc), are therapeutic targets of various anticancer drugs. TOPcc can also form on damaged DNA during replication and transcription, and engage specific repair pathways, such as those mediated by tyrosyl-DNA phosphodiesterase 1 (TDP1) and TDP2 and by endonucleases (MRE11, XPF-ERCC1 and MUS81)...
September 21, 2016: Nature Reviews. Molecular Cell Biology
Pauline Chanut, Sébastien Britton, Julia Coates, Stephen P Jackson, Patrick Calsou
Repair of single-ended DNA double-strand breaks (seDSBs) by homologous recombination (HR) requires the generation of a 3' single-strand DNA overhang by exonuclease activities in a process called DNA resection. However, it is anticipated that the highly abundant DNA end-binding protein Ku sequesters seDSBs and shields them from exonuclease activities. Despite pioneering works in yeast, it is unclear how mammalian cells counteract Ku at seDSBs to allow HR to proceed. Here we show that in human cells, ATM-dependent phosphorylation of CtIP and the epistatic and coordinated actions of MRE11 and CtIP nuclease activities are required to limit the stable loading of Ku on seDSBs...
September 19, 2016: Nature Communications
Valentina Palermo, Sara Rinalducci, Massimo Sanchez, Francesca Grillini, Joshua A Sommers, Robert M Brosh, Lello Zolla, Annapaola Franchitto, Pietro Pichierri
Regulation of end-processing is critical for accurate repair and to switch between homologous recombination (HR) and non-homologous end joining (NHEJ). End resection is a two-stage process but very little is known about regulation of the long-range resection, especially in humans. WRN participates in one of the two alternative long-range resection pathways mediated by DNA2 or EXO1. Here we demonstrate that phosphorylation of WRN by CDK1 is essential to perform DNA2-dependent end resection at replication-related DSBs, promoting HR, replication recovery and chromosome stability...
2016: Nature Communications
Hongjuan Zhang, Fang Wang, Chunjie Mao, Zuncheng Zhang, Shengjun Fu, Jianzhong Lu, Zhenxing Zhai, Renju Li, Shuwen Li, Ron Rodriguez, Zhiping Wang
PURPOSE: Gene therapy combined with radiation has shown promising potential for the treatment of tumors. This paper aimed to clarify the synergistic effect of radiotherapy combined with the bladder cancer tissue-specific oncolytic adenovirus (Ad-PSCAE-UPII-E1A) on bladder cancer cells and to study the underlying synergy mechanisms of the combined treatment. MATERIALS AND METHODS: The Adenovirus carrying E1A under control of UPII promoter and prostate stem cell antigen enhancer (PSCAE) were successfully constructed...
October 14, 2016: International Journal of Radiation Biology
Seung Ho Choi, Hae Yong Yoo
TopBP1 has been identified as a direct activator of ATR and interacts with the Nbs1 subunit of the Mre11-Rad50-Nbs1 (MRN) complex in egg extracts in a checkpoint-regulated manner. In this study, we show that Mdc1 associates with both TopBP1 and Nbs1 in egg extracts and human cells. We cloned a cDNA encoding the full-length version of Xenopus Mdc1. The association between Mdc1 and TopBP1 involves the first pair of BRCT repeats in TopBP1. The N-terminal region (161-230) of Mdc1 is required for this binding. The interaction between Mdc1 and Nbs1 involves the two tandem BRCT repeats of Nbs1...
October 7, 2016: Biochemical and Biophysical Research Communications
Yang Gao, Jennifer R Kaczynski, Scott W Nelson
The Mre11-Rad50 (MR) protein complex, made up of a nuclease and ATPase, respectively, is involved in the processing of double-strand breaks as part of an intricate mechanism for their repair. Although it is clear that the MR complex is subject to allosteric regulation and that there is communication between the nuclease and ATPase active sites, the underlying mechanisms are poorly understood. We performed statistical coupling analysis (SCA) on the Mre11 and Rad50 to predict linked residues based on their evolutionary correlation...
August 29, 2016: Protein Science: a Publication of the Protein Society
Christopher J Staples, Giancarlo Barone, Katie N Myers, Anil Ganesh, Ian Gibbs-Seymour, Abhijit A Patil, Ryan D Beveridge, Caroline Daye, Richard Beniston, Sarah Maslen, Ivan Ahel, J Mark Skehel, Spencer J Collis
Through an RNAi-based screen for previously uncharacterized regulators of genome stability, we have identified the human protein C5orf45 as an important factor in preventing the accumulation of DNA damage in human cells. Here, we functionally characterize C5orf45 as a binding partner of the MRE11-RAD50-NBS1 (MRN) damage-sensing complex. Hence, we rename C5orf45 as MRNIP for MRN-interacting protein (MRNIP). We find that MRNIP is rapidly recruited to sites of DNA damage. Cells depleted of MRNIP display impaired chromatin loading of the MRN complex, resulting in reduced DNA end resection and defective ATM-mediated DNA damage signaling, a reduced ability to repair DNA breaks, and radiation sensitivity...
September 6, 2016: Cell Reports
Shubhankar Suman, Santosh Kumar, Prosper N'Gouemo, Kamal Datta
Binge drinking is known to cause damage in critical areas of the brain, including the hippocampus, which is important for relational memory and is reported to be sensitive to alcohol toxicity. However, the roles of DNA double-strand break (DSB) and its repair pathways, homologous recombination (HR), and non-homologous end joining (NHEJ) in alcohol-induced hippocampal injury remain to be elucidated. The purpose of this first study was to assess alcohol-induced DNA DSB and the mechanism by which alcohol affects DSB repair pathways in rat hippocampus...
August 2016: Alcohol
Vijayakumar Govindaraj, Harshini Krishnagiri, Manmohan Singh Chauhan, A J Rao
In our previous study, we demonstrated that the repair efficiency of DNA double-strand breaks declines with increasing age in rat primordial follicles. In the present study, we extended our studies to buffalo (Bubalus bubalis) wherein we studied the expression of BRCA-1 related DNA repair genes in primordial follicles of young (12 months-22 months) and adult (72-96 months) buffaloes. The relative expression of selected genes, as determined by RT-PCR, revealed a significant (p < 0.05) decrease in mRNA levels of BRCA1, MRE11, RAD51, ATM, and H2AX in adult primordial follicles as compared to the young...
August 23, 2016: Animal Biotechnology
Ilgen Mender, Jerry W Shay
Telomerase maintains telomeric DNA in eukaryotes during early developments, ~90% of cancer cells and some proliferative stem like cells. Telomeric repeats at the end of chromosomes are associated with the shelterin complex. This complex consists of TRF1, TRF2, Rap1, TIN2, TPP1, POT1 which protect DNA from being recognized as DNA double-stranded breaks. Critically short telomeres or impaired shelterin proteins can cause telomere dysfunction, which eventually induces DNA damage responses at the telomeres. DNA damage responses can be identified by antibodies to 53BP1, gammaH2AX, Rad17, ATM, and Mre11...
November 20, 2015: Bio-protocol
Xia Ding, Arnab Ray Chaudhuri, Elsa Callen, Yan Pang, Kajal Biswas, Kimberly D Klarmann, Betty K Martin, Sandra Burkett, Linda Cleveland, Stacey Stauffer, Teresa Sullivan, Aashish Dewan, Hanna Marks, Anthony T Tubbs, Nancy Wong, Eugen Buehler, Keiko Akagi, Scott E Martin, Jonathan R Keller, André Nussenzweig, Shyam K Sharan
Poly (ADP-ribose) polymerase (PARP) inhibitor (PARPi) olaparib has been approved for treatment of advanced ovarian cancer associated with BRCA1 and BRCA2 mutations. BRCA1- and BRCA2-mutated cells, which are homologous recombination (HR) deficient, are hypersensitive to PARPi through the mechanism of synthetic lethality. Here we examine the effect of PARPi on HR-proficient cells. Olaparib pretreatment, PARP1 knockdown or Parp1 heterozygosity of Brca2(cko/ko) mouse embryonic stem cells (mESCs), carrying a null (ko) and a conditional (cko) allele of Brca2, results in viable Brca2(ko/ko) cells...
August 8, 2016: Nature Communications
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"