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Mol Cell. 2016 Jul 21;63(2):293-305. doi: 10.1016/j.molcel.2016.06.002. Epub 2016 Jul 7.

Temporal and Spatial Uncoupling of DNA Double Strand Break Repair Pathways within Mammalian Heterochromatin.

Author information

1
Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Centre National de Recherche Scientifique, UMR7104, 67404 Illkirch, France; Université de Strasbourg, 67081 Strasbourg, France.
2
Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland.
3
Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Centre National de Recherche Scientifique, UMR7104, 67404 Illkirch, France; Université de Strasbourg, 67081 Strasbourg, France. Electronic address: reinab@igbmc.fr.
4
Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Centre National de Recherche Scientifique, UMR7104, 67404 Illkirch, France; Université de Strasbourg, 67081 Strasbourg, France. Electronic address: evisou@igbmc.fr.

Abstract

Repetitive DNA is packaged into heterochromatin to maintain its integrity. We use CRISPR/Cas9 to induce DSBs in different mammalian heterochromatin structures. We demonstrate that in pericentric heterochromatin, DSBs are positionally stable in G1 and recruit NHEJ factors. In S/G2, DSBs are resected and relocate to the periphery of heterochromatin, where they are retained by RAD51. This is independent of chromatin relaxation but requires end resection and RAD51 exclusion from the core. DSBs that fail to relocate are engaged by NHEJ or SSA proteins. We propose that the spatial disconnection between end resection and RAD51 binding prevents the activation of mutagenic pathways and illegitimate recombination. Interestingly, in centromeric heterochromatin, DSBs recruit both NHEJ and HR proteins throughout the cell cycle. Our results highlight striking differences in the recruitment of DNA repair factors between pericentric and centromeric heterochromatin and suggest a model in which the commitment to specific DNA repair pathways regulates DSB position.

PMID:
27397684
DOI:
10.1016/j.molcel.2016.06.002
[Indexed for MEDLINE]
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