PARP-1 activation regulates the DNA damage response to DNA double-strand breaks

Authors: Krietsch, Jana
Advisor: Masson, Jean-YvesRouleau, Michèle
Abstract: DNA double-strand breaks are potentially lethal lesions, which if not repaired correctly, can have harmful consequences such as carcinogenesis promoted by chromosome deletions and rearrangements. Poly(ADP-ribosyl)ation carried out by poly(ADP-ribose) polymerase 1 (PARP-1) is one of the first posttranslational modifications occurring in response to DNA damage. In brief, PARP-1 uses nicotinamide to generate a negatively charged polymer called poly(ADP-ribose) polymer (PAR), that can be attached to acceptor proteins, which is to a large extent PARP-1 itself. PAR has recently been recognized as a recruitment signal for key DNA repair proteins to sites of DNA damage but the precise role of PARP-1 and its catalytic product PAR in the DNA damage response are still a matter of ongoing debate. Throughout my doctoral work, we confirmed that the proteins in complex with PAR promptly after DNA damage are mostly DNA repair proteins, whereas during the period of recovery from DNA damage, the PAR interactome is highly enriched with RNA processing factors. Interestingly, one of the most abundant RNA-binding proteins detected in the PAR interactome, namely NONO, did not follow these kinetics as it was highly enriched immediately after DNA damage in the DNA repair protein complexes centered on PAR. Our subsequent investigation of NONO in the DNA damage response to double-strand breaks strikingly revealed a direct implication for NONO in repair by nonhomologous end joining (NHEJ). Moreover, we found that NONO strongly and specifically binds to PAR through its RNA-recognition motif 1 (RRM1), highlighting competition between PAR and RNA for the same binding site. Remarkably, the in vivo recruitment of NONO to DNA damage sites completely depends on PAR and requires the RRM1 motif. In conclusion, our results establish NONO as a new protein implicated in the DNA damage response to double-strand break and in broader terms add another layer of complexity to the cross-talk between RNA-biology and DNA repair.
Document Type: Thèse de doctorat
Issue Date: 2014
Open Access Date: 20 April 2018
Grantor: Université Laval
Collection:Thèses et mémoires

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