Structure-specific DNA endonuclease Mus81/Eme1 generates DNA damage caused by Chk1 inactivation.

The DNA-damage checkpoint kinase Chk1 is essential in higher eukaryotes due to its role in maintaining genome stability in proliferating cells. CHK1 gene deletion is embryonically lethal, and Chk1 inhibition in replicating cells causes cell-cycle defects that eventually lead to perturbed replication and replication-fork collapse, thus generating endogenous DNA damage. What is the cause of replication-fork collapse when Chk1 is inactivated, however, remains poorly understood. Here, we show that generation of DNA double-strand breaks at replication forks when Chk1 activity is compromised relies on the DNA endonuclease complex Mus81/Eme1. Importantly, we show that Mus81/Eme1-dependent DNA damage--rather than a global increase in replication-fork stalling--is the cause of incomplete replication in Chk1-deficient cells. Consequently, Mus81/Eme1 depletion alleviates the S-phase progression defects associated with Chk1 deficiency, thereby increasing cell survival. Chk1-mediated protection of replication forks from Mus81/Eme1 even under otherwise unchallenged conditions is therefore vital to prevent uncontrolled fork collapse and ensure proper S-phase progression in human cells

Synthetic viability genomic screening defines Sae2 function in DNA repair.

DNA double-strand break (DSB) repair by homologous recombination (HR) requires 3' single-stranded DNA (ssDNA) generation by 5' DNA-end resection. During meiosis, yeast Sae2 cooperates with the nuclease Mre11 to remove covalently bound Spo11 from DSB termini, allowing resection and HR to ensue. Mitotic roles of Sae2 and Mre11 nuclease have remained enigmatic, however, since cells lacking these display modest resection defects but marked DNA damage hypersensitivities. By combining classic genetic suppressor screening with high-throughput DNA sequencing, we identify Mre11 mutations that strongly suppress DNA damage sensitivities of sae2∆ cells. By assessing the impacts of these mutations at the cellular, biochemical and structural levels, we propose that, in addition to promoting resection, a crucial role for Sae2 and Mre11 nuclease activity in mitotic DSB repair is to facilitate the removal of Mre11 from ssDNA associated with DSB ends. Thus, without Sae2 or Mre11 nuclease activity, Mre11 bound to partly processed DSBs impairs strand invasion and HR.We thank M.P. Longhese, R. Rothstein and J. Haber for providing strains and plasmids; Sir T. Blundell and T. Ochi for advice on structural biology and for providing comments to the manuscript. Research in the Jackson laboratory is funded by Cancer Research UK Programme Grant C6/A11224, the European Research Council and the European Community Seventh Framework Programme Grant Agreement No. HEALTH‐F2‐2010‐259893 (DDResponse). Core funding is provided by CRUK (C6946/A14492) and the Wellcome Trust (WT092096). SPJ receives his salary from the University of Cambridge, UK, supplemented by CRUK. TO, IG and FP were funded by Framework Programme Grant Agreement No. HEALTH‐F2‐2010‐259893 (DDResponse). FP also received funding from EMBO (Fellowship ALTF 1287‐2011); NG and IS are funded by the Wellcome Trust (101126/Z/13/Z). DJA and TMK were supported by Cancer Research UK and the Wellcome Trust (WT098051). PS and HN were supported by NIH grants RO1ES007061 and K99ES021441, respectively.This is the final version. It was first published by EMBO at http://emboj.embopress.org/content/early/2015/04/21/embj.201590973.lon

Synthetic viability genomic screening defines Sae2 function in DNA repair.

DNA double-strand break (DSB) repair by homologous recombination (HR) requires 3' single-stranded DNA (ssDNA) generation by 5' DNA-end resection. During meiosis, yeast Sae2 cooperates with the nuclease Mre11 to remove covalently bound Spo11 from DSB termini, allowing resection and HR to ensue. Mitotic roles of Sae2 and Mre11 nuclease have remained enigmatic, however, since cells lacking these display modest resection defects but marked DNA damage hypersensitivities. By combining classic genetic suppressor screening with high-throughput DNA sequencing, we identify Mre11 mutations that strongly suppress DNA damage sensitivities of sae2∆ cells. By assessing the impacts of these mutations at the cellular, biochemical and structural levels, we propose that, in addition to promoting resection, a crucial role for Sae2 and Mre11 nuclease activity in mitotic DSB repair is to facilitate the removal of Mre11 from ssDNA associated with DSB ends. Thus, without Sae2 or Mre11 nuclease activity, Mre11 bound to partly processed DSBs impairs strand invasion and HR.We thank M.P. Longhese, R. Rothstein and J. Haber for providing strains and plasmids; Sir T. Blundell and T. Ochi for advice on structural biology and for providing comments to the manuscript. Research in the Jackson laboratory is funded by Cancer Research UK Programme Grant C6/A11224, the European Research Council and the European Community Seventh Framework Programme Grant Agreement No. HEALTH‐F2‐2010‐259893 (DDResponse). Core funding is provided by CRUK (C6946/A14492) and the Wellcome Trust (WT092096). SPJ receives his salary from the University of Cambridge, UK, supplemented by CRUK. TO, IG and FP were funded by Framework Programme Grant Agreement No. HEALTH‐F2‐2010‐259893 (DDResponse). FP also received funding from EMBO (Fellowship ALTF 1287‐2011); NG and IS are funded by the Wellcome Trust (101126/Z/13/Z). DJA and TMK were supported by Cancer Research UK and the Wellcome Trust (WT098051). PS and HN were supported by NIH grants RO1ES007061 and K99ES021441, respectively.This is the final version. It was first published by EMBO at http://emboj.embopress.org/content/early/2015/04/21/embj.201590973.lon

Proceedings of the Fifth Italian Conference on Computational Linguistics CLiC-it 2018

On behalf of the Program Committee, a very warm welcome to the Fifth Italian Conference on Computational Linguistics (CLiC-­‐it 2018). This edition of the conference is held in Torino. The conference is locally organised by the University of Torino and hosted into its prestigious main lecture hall “Cavallerizza Reale”. The CLiC-­‐it conference series is an initiative of the Italian Association for Computational Linguistics (AILC) which, after five years of activity, has clearly established itself as the premier national forum for research and development in the fields of Computational Linguistics and Natural Language Processing, where leading researchers and practitioners from academia and industry meet to share their research results, experiences, and challenges

Role of the Saccharomyces cerevisiae Rad53 Checkpoint Kinase in Signaling Double-Strand Breaks during the Meiotic Cell Cycle▿

DNA double-strand breaks (DSBs) can arise at unpredictable locations after DNA damage or in a programmed manner during meiosis. DNA damage checkpoint response to accidental DSBs during mitosis requires the Rad53 effector kinase, whereas the meiosis-specific Mek1 kinase, together with Red1 and Hop1, mediates the recombination checkpoint in response to programmed meiotic DSBs. Here we provide evidence that exogenous DSBs lead to Rad53 phosphorylation during the meiotic cell cycle, whereas programmed meiotic DSBs do not. However, the latter can trigger phosphorylation of a protein fusion between Rad53 and the Mec1-interacting protein Ddc2, suggesting that the inability of Rad53 to transduce the meiosis-specific DSB signals might be due to its failure to access the meiotic recombination sites. Rad53 phosphorylation/activation is elicited when unrepaired meiosis-specific DSBs escape the recombination checkpoint. This activation requires homologous chromosome segregation and delays the second meiotic division. Altogether, these data indicate that Rad53 prevents sister chromatid segregation in the presence of unrepaired programmed meiotic DSBs, thus providing a salvage mechanism ensuring genetic integrity in the gametes even in the absence of the recombination checkpoint

Le varietà dell'italiano contemporaneo

Il volume offre uno sguardo aggiornato sullo stato dell'italiano contemporaneo, prendendo in esame i quadranti dell'architettura della lingua e tutti gli assi su cui tradizionalmente si articola la descrizione sociolinguistica. I diversi capitoli che lo compongono forniscono una panoramica il più possibile completa sulla lingua nazionale, passando in rassegna alcune delle varietà di maggiore rilevanza. Oltre al “vecchio” e al “nuovo” standard, sono considerate varietà più spiccatamente caratterizzate dal punto di vista diatopico, diastratico, diafasico e diamesico. In appendice sono riportate alcune brevi descrizioni di corpora di recente creazione, che costituiscono strumenti di grande utilità e importanza per chi vuole affrontare lo studio della variazione

Genomic Characterization of Concurrent Alterations in Non-Small Cell Lung Cancer (NSCLC) Harboring Actionable Mutations

An increasing number of driver genomic alterations with potential targeted treatments have been identified in non-small cell lung cancer (NSCLC). Much less is known about the incidence and different distribution of concurrent alterations, as identified by comprehensive genomic profiling in oncogene-addicted NSCLCs. Genomic data from advanced NSCLC consecutively analyzed using a broad next-generation sequencing panel were retrospectively collected. Tumors harboring at least one main actionable gene alteration were categorized according to the presence/absence of concurrent genomic aberrations, to evaluate different patterns among the main oncogene-addicted NSCLCs. Three-hundred-nine actionable gene alterations were identified in 284 advanced NSCLC patients during the study period. Twenty-five tumor samples (8%) displayed concurrent alterations in actionable genes. Co-occurrences involving any pathogenic variant or copy number variation (CNV) were identified in 82.8% of cases. Overall, statistically significant differences in the number of concurrent alterations, and the distribution of TP53, STK11, cyclines and receptor tyrosin kinase (RTK) aberrations were observed across the eight actionable gene groups. NGS analyses of oncogene-addicted NSCLCs showed a different distribution and pattern of co-alteration profiles. Further investigations are needed to evaluate the prognostic and treatment-related impact of these concurrent alterations, hooked to the main gene aberrations