Single-stranded DNA oligomers stimulate error-prone alternative repair of DNA double-strand breaks through hijacking Ku protein.
In humans, DNA double-strand breaks (DSBs) are repaired by two mutually-exclusive mechanisms, homologous recombination or end-joining. Among end-joining mechanisms, the main process is classical non-homologous end-joining (C-NHEJ) which relies on Ku binding to DNA ends and DNA Ligase IV (Lig4)-mediated ligation. Mostly under Ku- or Lig4-defective conditions, an alternative end-joining process (A-EJ) can operate and exhibits a trend toward microhomology usage at the break junction. Homologous recombination relies on an initial MRN-dependent nucleolytic degradation of one strand at DNA ends. This process, named DNA resection generates 3' single-stranded tails necessary for homologous pairing with the sister chromatid. While it is believed from the current literature that the balance between joining and recombination processes at DSBs ends is mainly dependent on the initiation of resection, it has also been shown that MRN activity can generate short single-stranded DNA oligonucleotides (ssO) that may also be implicated in repair regulation. Here, we evaluate the effect of ssO on end-joining at DSB sites both in vitro and in cells. We report that under both conditions, ssO inhibit C-NHEJ through binding to Ku and favor repair by the Lig4-independent microhomology-mediated A-EJ process.
CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France Equipe labellisée Ligue Nationale Contre le Cancer, France.
Ying
Y
Yuan
CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France Equipe labellisée Ligue Nationale Contre le Cancer, France.
Sébastien
S
Britton
CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France Equipe labellisée Ligue Nationale Contre le Cancer, France.
Christine
C
Delteil
The Wellcome Trust and Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, CB2 1QN England, UK.
Julia
J
Coates
The Wellcome Trust and Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, CB2 1QN England, UK.
Stephen P
SP
Jackson
CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France Equipe labellisée Ligue Nationale Contre le Cancer, France.
Nadia
N
Barboule
CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France Equipe labellisée Ligue Nationale Contre le Cancer, France.
Philippe
P
Frit
CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France Equipe labellisée Ligue Nationale Contre le Cancer, France calsou@ipbs.fr.
Patrick
P
Calsou
D034961:Antigens, Nuclear / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D000072200:Ku Autoantigen; D009838:Oligodeoxyribonucleotides / Q000378:metabolism
D034961:Antigens, Nuclear; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D004247:DNA; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen