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Teresa Morales-Ruiz, Álvaro C Romero-Valenzuela, Vanessa M Vázquez-Grande, Teresa Roldán-Arjona, Rafael R Ariza, Dolores Córdoba-Cañero
Base excision repair (BER) is a major defense pathway against spontaneous DNA damage. This multistep process is initiated by DNA glycosylases that recognise and excise the damaged base, and proceeds by the concerted action of additional proteins that perform incision of the abasic site, gap filling and ligation. BER has been extensively studied in bacteria, yeasts and animals. Although knowledge of this pathway in land plants is increasing, there are no reports detecting BER in algae. We describe here an experimental in vitro system allowing the specific analysis of BER in the model alga Chlamydomonas reinhardtii...
March 5, 2018: DNA Repair
Tales Rocha de Moura, Sina Mozaffari-Jovin, Csaba Zoltán Kibédi Szabó, Jana Schmitzová, Olexandr Dybkov, Constantin Cretu, Michael Kachala, Dmitri Svergun, Henning Urlaub, Reinhard Lührmann, Vladimir Pena
Human nineteen complex (NTC) acts as a multimeric E3 ubiquitin ligase in DNA repair and splicing. The transfer of ubiquitin is mediated by Prp19-a homotetrameric component of NTC whose elongated coiled coils serve as an assembly axis for two other proteins called SPF27 and CDC5L. We find that Prp19 is inactive on its own and have elucidated the structural basis of its autoinhibition by crystallography and mutational analysis. Formation of the NTC core by stepwise assembly of SPF27, CDC5L, and PLRG1 onto the Prp19 tetramer enables ubiquitin ligation...
March 15, 2018: Molecular Cell
Radoslav Aleksandrov, Anton Dotchev, Ina Poser, Dragomir Krastev, Georgi Georgiev, Greta Panova, Yordan Babukov, Georgi Danovski, Teodora Dyankova, Lars Hubatsch, Aneliya Ivanova, Aleksandar Atemin, Marina N Nedelcheva-Veleva, Susanne Hasse, Mihail Sarov, Frank Buchholz, Anthony A Hyman, Stephan W Grill, Stoyno S Stoynov
A single mutagen can generate multiple different types of DNA lesions. How different repair pathways cooperate in complex DNA lesions, however, remains largely unclear. Here we measured, clustered, and modeled the kinetics of recruitment and dissociation of 70 DNA repair proteins to laser-induced DNA damage sites in HeLa cells. The precise timescale of protein recruitment reveals that error-prone translesion polymerases are considerably delayed compared to error-free polymerases. We show that this is ensured by the delayed recruitment of RAD18 to double-strand break sites...
March 15, 2018: Molecular Cell
Yang Chen, Youyou Wang, Lujun Zhao, Ping Wang, Jifeng Sun, Rudi Bao, Chenghai Li, Ningbo Liu
Objective: To investigate the potential of HS-10182, a second-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), as a radiosensitizer in non-small cell lung cancer (NSCLC). Methods: Two cell lines of NSCLCs, A549 that possesses wild-type (WT) EGFRs and H1975 that possesses EGFR L858R/T790M double mutations, were treated with HS-10182 at various concentrations, and cell viabilities were determined using the MTS assay. The cells were tested by clonogenic survival assays to identify the radiosensitivity of both groups...
February 2018: Cancer Biology & Medicine
Francesca Vena, Ruochen Jia, Arman Esfandiari, Juan J Garcia-Gomez, Manuel Rodriguez-Justo, Jianguo Ma, Sakeena Syed, Lindsey Crowley, Brian Elenbaas, Samantha Goodstal, John A Hartley, Daniel Hochhauser
Targeting the DNA damage response (DDR) in tumors with defective DNA repair is a clinically successful strategy. The RAS/RAF/MEK/ERK signalling pathway is frequently deregulated in human cancers. In this study, we explored the effects of MEK inhibition on the homologous recombination pathway and explored the potential for combination therapy of MEK inhibitors with DDR inhibitors and a hypoxia-activated prodrug. We studied effects of combining pimasertib, a selective allosteric inhibitor of MEK1/2, with olaparib, a small molecule inhibitor of poly (adenosine diphosphate [ADP]-ribose) polymerases (PARP), and with the hypoxia-activated prodrug evofosfamide in ovarian and pancreatic cancer cell lines...
February 20, 2018: Oncotarget
S Wang, Z Zou, X Luo, Y Mi, H Chang, D Xing
Liver receptor homolog-1 (LRH1) has been shown to promote tumor proliferation and development. However, the functions of LRH1 in mediating cancer cells chemoresistance are still not clear. Here, we found LRH1 levels were significantly elevated in primary breast cancer tissues in patients who developed early recurrence. Similarly, adriamycin (ADR)-resistant breast cancer cell lines also exerted high LRH1 expression. Indeed, overexpression of LRH1 attenuated cytotoxicity of chemotherapeutic drugs ADR and cisplatin (DDP) in breast cancer cells in vitro and in nude mice tumor model...
March 16, 2018: Oncogene
Péter Nagy, Gyöngyvér O Sándor, Gábor Juhász
Intestinal homeostasis is maintained by tightly controlled proliferation and differentiation of tissue-resident multipotent stem cells during aging and regeneration, which ensures organismal adaptation. Here we show that autophagy is required in Drosophila intestinal stem cells to sustain proliferation, and preserves the stem cell pool. Autophagy-deficient stem cells show elevated DNA damage and cell cycle arrest during aging, and are frequently eliminated via JNK-mediated apoptosis. Interestingly, loss of Chk2, a DNA damage-activated kinase that arrests the cell cycle and promotes DNA repair and apoptosis, leads to uncontrolled proliferation of intestinal stem cells regardless of their autophagy status...
March 15, 2018: Scientific Reports
Pingping Fang, Jill A Madden, Lisa Neums, K Ryan Moulder, M Laird Forrest, Jeremy Chien
FOXM1 transcription factor network is activated in over 84% of cases in high-grade serous ovarian cancer (HGSOC), and FOXM1 upregulates the expression of genes involved in the homologous recombination (HR) DNA damage and repair (DDR) pathway. However, the role of FOXM1 in poly (ADP-ribose) polymerase (PARP) inhibitor response has not yet been studied. The present study demonstrates that PARP inhibitor (PARPi), olaparib, induces the expression and nuclear localization of FOXM1. Based on ChIP-qPCR, olaparib enhances the binding of FOXM1 to genes involved in HR repair...
March 15, 2018: Molecular Cancer Research: MCR
Jinfeng Cui, Juan Wang, Shujuan Huang, Xiujuan Jiang, Yuehong Li, Wenxin Wu, Xianghong Zhang
Sterigmatocystin (ST), being a precursor of aflatoxin, is categorized as Group 2B carcinogen. Our previous studies found that both mismatch repair (MMR) pathways and p53 signaling pathway were involved in ST-induced G2 cell cycle arrest in human esophageal squamous epithelial cell line, HET-1A, in vitro. Studies showed that ERK, JNK and p38 signaling pathways played important roles in cell cycle arrest induced by several other carcinogens. However, the role of MAPK pathway and the links between the MMR and p53 signaling pathways in ST induced G2 phase arrest is still not clarified...
March 12, 2018: Food and Chemical Toxicology
Pingping Jia, Weihang Chai
Genome instability gives rise to cancer. MLH1, commonly known for its important role in mismatch repair (MMR), DNA damage signaling and double-strand break (DSB) repair, safeguards genome stability. Recently we have reported a novel role of MLH1 in preventing aberrant formation of interstitial telomeric sequences (ITSs) at intra-chromosomal regions. Deficiency in MLH1, in particular its N-terminus, leads to an increase of ITSs. Here, we identify that the ATPase activity in the MLH1 N-terminal domain is important for suppressing the formation of ITSs...
March 7, 2018: DNA Repair
Qing Cai, Sen-Miao Tong, Wei Shao, Sheng-Hua Ying, Ming-Guang Feng
Histone acetyltransferases (HATs) and deacetylases (HDACs) maintain dynamics of lysine acetylation/deacetylation on histones and non-histone substrates involved in gene regulation and cellular events. Hos2 is a class I HDAC that deacetylates unique histone H4-K16 site in yeasts. Here, we report that orthologous Hos2 deacetylates H4-K16 and is also involved in the acetylation of histone H3-K56 and the phosphorylation of histone H2A-S129 and cyclin-dependent kinase 1 CDK1-Y15 in Beauveria bassiana, a filamentous fungal insect pathogen...
March 15, 2018: Cellular Microbiology
Matheus Roque, Sandro C Esteves
Varicocele, the leading cause of male infertility, can impair sperm quality and fertility via various oxidative stress mechanisms. An imbalance between excessive reactive oxygen species production and antioxidant protection causes alterations in nuclear and mitochondrial sperm DNA, thus rendering a subset of varicocele men less fertile. In particular, sperm DNA fragmentation is usually elevated in men with clinical varicocele in both abnormal and normal semen parameters by the current World Health Organization criteria...
March 14, 2018: International Urology and Nephrology
(no author information available yet)
Andrew McAinsh received his PhD from the University of Cambridge, UK, working in the laboratory of Steve Jackson on DNA damage and repair mechanisms in yeast. He then joined the laboratory of Peter Sorger as a Jane Coffin Childs Fellow to work as a post-doc on kinetochore biology at the Massachusetts Institute of Technology, Boston, USA. In 2005, he returned to the UK to establish his independent laboratory at the Marie Curie Research Institute, Surrey, before moving to the University of Warwick in 2009 to co-found the Centre for Mechanochemical Cell Biology (CMCB)...
March 14, 2018: Journal of Cell Science
D Hernandez-Cortes, I Alvarado-Cruz, M J Solís-Heredia, B Quintanilla-Vega
Methyl parathion (Me-Pa) is an oxidizing organophosphate (OP) pesticide that generates reactive oxygen species (ROS) through its biotransformation. Some studies have also suggested that OP pesticides have the capacity to alkylate biomolecules, including DNA. In general, DNA methylation in gene promoters represses transcription. NRF2 is a key transcription factor that regulates the expression of antioxidant, metabolic and detoxifying genes through the antioxidant response element (ARE) situated in promoters of regulated genes...
March 11, 2018: Toxicology and Applied Pharmacology
Prachi Borude, Bharat Bhushan, Udayan Apte
Acetaminophen (APAP) overdose is the leading cause of Acute Liver Failure (ALF) with limited treatment options. It is known that liver regeneration following APAP induced ALF is a deciding factor in the final outcome. Previous studies from our laboratory using incremental dose model involving a regenerating (300 mg/kg, APAP300) and a non-regenerating (600 mg/kg, APAP600) dose of APAP in mice have revealed several pro- regenerative pathways that regulate regeneration after APAP overdose. Here we report that DNA damage and repair mechanisms regulate initiation liver regeneration following APAP overdose...
March 14, 2018: Gene Expression
Luz I Valenzuela-García, Víctor M Ayala-García, Ana G Regalado-García, Peter Setlow, Mario Pedraza-Reyes
The absence of base excision repair (BER) proteins involved in processing ROS-promoted genetic insults activates a DNA damage scanning (DisA)-dependent checkpoint event in outgrowing Bacillus subtilis spores. Here, we report that genetic disabling of transcription-coupled repair (TCR) or nucleotide excision repair (NER) pathways severely affected outgrowth of ΔdisA spores, and much more so than the effects of these mutations on log phase growth. This defect delayed the first division of spore's nucleoid suggesting that unrepaired lesions affected transcription and/or replication during outgrowth...
March 13, 2018: MicrobiologyOpen
Triparna Sen, Carl M Gay, Lauren Averett Byers
Small cell lung cancer (SCLC) is an aggressive malignancy that accounts for 14% of all lung cancer diagnoses. Despite decades of active research, treatment options for SCLC are limited and resistance to the few Food and Drug Administration (FDA) approved therapies develops rapidly. With no approved targeted agents to date, new therapeutic strategies are desperately needed. SCLC is characterized by high mutation burden, ubiquitous loss of TP53 and RB1, mutually exclusive amplification of MYC family members, thereby, high genomic instability...
February 2018: Translational Lung Cancer Research
Tadashige Nozaki, Yuka Sasaki, Itsuko Fukuda, Mayu Isumi, Keitaro Nakamoto, Takae Onodera, Mitsuko Masutani
Poly (ADP-ribose) polymerase family, member 1 (Parp1) has pleiotropic and disparate functions in multiple cellular signaling pathways through post-translational protein modification. It contributes to the regulation of various cellular processes, including DNA damage repair, cell death, and cell differentiation, genetically or epigenetically. Meanwhile, the functions of Parp1 in intercellular signaling remain to be established. To examine the functions of Parp1 in intercellular signaling, we examined microRNA (miRNA) regulation in exosomes derived from Parp1-deficient (Parp1-/- ) embryonic stem (ES) cells...
March 10, 2018: Biochemical and Biophysical Research Communications
Xia Cao, Hetong Wang, Defeng Zhuang, He Zhu, Yanli Du, Zhibo Cheng, Weina Cui, Hilary J Rogers, Qianru Zhang, Chunjun Jia, Yuesuo Yang, Peidong Tai, Futi Xie, Wan Liu
DNA mismatch repair (MMR) proteins have been implicated in sensing and correcting DNA damage, and in governing cell cycle progression in the presence of structurally anomalous nucleotide lesions induced by different stresses in mammalian cells. Here, Arabidopsis seedlings were grown hydroponically on 0.5 × MS media containing cadmium (Cd) at 0-4.0 mg L-1 for 5 d. Flow cytometry results indicated that Cd stress induced a G2/M cell cycle arrest both in MLH1-, MSH2-, MSH6-deficient, and in WT roots, associated with marked changes of G2/M regulatory genes, including ATM, ATR, SOG1, BRCA1, WEE1, CYCD4; 1, MAD2, CDKA;1, CYCB1; 2 and CYCB1; 1...
March 3, 2018: Chemosphere
Alex Pines, Madelon Dijk, Matthew Makowski, Elisabeth M Meulenbroek, Mischa G Vrouwe, Yana van der Weegen, Marijke Baltissen, Pim J French, Martin E van Royen, Martijn S Luijsterburg, Leon H Mullenders, Michiel Vermeulen, Wim Vermeulen, Navraj S Pannu, Haico van Attikum
Transcription-blocking DNA lesions are removed by transcription-coupled nucleotide excision repair (TC-NER) to preserve cell viability. TC-NER is triggered by the stalling of RNA polymerase II at DNA lesions, leading to the recruitment of TC-NER-specific factors such as the CSA-DDB1-CUL4A-RBX1 cullin-RING ubiquitin ligase complex (CRLCSA ). Despite its vital role in TC-NER, little is known about the regulation of the CRLCSA complex during TC-NER. Using conventional and cross-linking immunoprecipitations coupled to mass spectrometry, we uncover a stable interaction between CSA and the TRiC chaperonin...
March 12, 2018: Nature Communications
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