title: NONO regulates the intra-S-phase checkpoint in response to UV radiation.
abstract: The main risk factor for skin cancer is ultraviolet (UV) exposure, which causes DNA damage. Cells respond to UV-induced DNA damage by activating the intra-S-phase checkpoint, which prevents replication fork collapse, late origin firing and stabilizes fragile sites. Recently, the 54-kDa multifunctional protein NONO was found to be involved in the non-homologous end-joining DNA repair process and in poly ADP-ribose polymerase 1 activation. Interestingly, NONO is mutated in several tumour types and emerged as a crucial factor underlying both melanoma development and progression. Therefore, we set out to evaluate whether NONO could be involved in the DNA-damage response to UV radiations. We generated NONO-silenced HeLa cell clones and found that lack of NONO decreased cell growth rate. Then, we challenged NONO-silenced cells with exposure to UV radiations and found that NONO-silenced cells, compared with control cells, continued to synthesize DNA, failed to block new origin firing and impaired CHK1S345 phosphorylation showing a defective checkpoint activation. Consistently, NONO is present at the sites of UV-induced DNA damage where it localizes to RAD9 foci. To position NONO in the DNA-damage response cascade, we analysed the loading onto chromatin of various intra-S-phase checkpoint mediators and found that NONO favours the loading of topoisomerase II-binding protein 1 acting upstream of the ATM and Rad3-related kinase activity. Strikingly, re-expression of NONO, through an sh-resistant mRNA, rescued CHK1S345 phosphorylation in NONO-silenced cells. Interestingly, NONO silencing affected cell response to UV radiations also in a melanoma cell line. Overall, our data uncover a new role for NONO in mediating the cellular response to UV-induced DNA damage.
authors.affiliation: CROM, Istituto Nazionale Tumori "Fondazione G. Pascale"- IRCCS, Naples, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Alfano
authors.affiliation: CROM, Istituto Nazionale Tumori "Fondazione G. Pascale"- IRCCS, Naples, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Costa
authors.affiliation: Department of Medicine, Surgery and Neuroscience, University of Siena and Istituto Toscano Tumori (ITT), Siena, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Caporaso
authors.affiliation: CROM, Istituto Nazionale Tumori "Fondazione G. Pascale"- IRCCS, Naples, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Altieri
authors.affiliation: Department of Medicine, Surgery and Neuroscience, University of Siena and Istituto Toscano Tumori (ITT), Siena, Italy.|Sbarro Institute for Cancer Research and Molecular Medicine and Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA, USA.
authors.forename: P
authors.initials: P
authors.lastname: Indovina
authors.affiliation: Sbarro Institute for Cancer Research and Molecular Medicine and Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA, USA.
authors.forename: M
authors.initials: M
authors.lastname: Macaluso
authors.affiliation: Department of Medicine, Surgery and Neuroscience, University of Siena and Istituto Toscano Tumori (ITT), Siena, Italy.|Sbarro Institute for Cancer Research and Molecular Medicine and Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA, USA.
authors.forename: A
authors.initials: A
authors.lastname: Giordano
authors.affiliation: CROM, Istituto Nazionale Tumori "Fondazione G. Pascale"- IRCCS, Naples, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Pentimalli
mesh_terms: D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins; D006367:HeLa Cells; D006801:Humans; D034521:Nuclear Matrix-Associated Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D050810:Octamer Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D059807:S Phase Cell Cycle Checkpoints / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects*; D014162:Transfection; D014466:Ultraviolet Rays
chemical_list: D004268:DNA-Binding Proteins; C083214:NONO protein, human; D034521:Nuclear Matrix-Associated Proteins; D050810:Octamer Transcription Factors; D016601:RNA-Binding Proteins; D004247:DNA