DNA ligase III promotes alternative nonhomologous end-joining during chromosomal translocation formation.

Abstract : Nonhomologous end-joining (NHEJ) is the primary DNA repair pathway thought to underlie chromosomal translocations and other genomic rearrangements in somatic cells. The canonical NHEJ pathway, including DNA ligase IV (Lig4), suppresses genomic instability and chromosomal translocations, leading to the notion that a poorly defined, alternative NHEJ (alt-NHEJ) pathway generates these rearrangements. Here, we investigate the DNA ligase requirement of chromosomal translocation formation in mouse cells. Mammals have two other DNA ligases, Lig1 and Lig3, in addition to Lig4. As deletion of Lig3 results in cellular lethality due to its requirement in mitochondria, we used recently developed cell lines deficient in nuclear Lig3 but rescued for mitochondrial DNA ligase activity. Further, zinc finger endonucleases were used to generate DNA breaks at endogenous loci to induce translocations. Unlike with Lig4 deficiency, which causes an increase in translocation frequency, translocations are reduced in frequency in the absence of Lig3. Residual translocations in Lig3-deficient cells do not show a bias toward use of pre-existing microhomology at the breakpoint junctions, unlike either wild-type or Lig4-deficient cells, consistent with the notion that alt-NHEJ is impaired with Lig3 loss. By contrast, Lig1 depletion in otherwise wild-type cells does not reduce translocations or affect microhomology use. However, translocations are further reduced in Lig3-deficient cells upon Lig1 knockdown, suggesting the existence of two alt-NHEJ pathways, one that is biased toward microhomology use and requires Lig3 and a back-up pathway which does not depend on microhomology and utilizes Lig1.
Type de document :
Article dans une revue
PLoS Genetics, Public Library of Science, 2011, 7 (6), pp.e1002080. 〈10.1371/journal.pgen.1002080〉
Liste complète des métadonnées

http://www.hal.inserm.fr/inserm-00715279
Contributeur : Delphine Autard <>
Soumis le : vendredi 6 juillet 2012 - 16:32:37
Dernière modification le : vendredi 18 mai 2018 - 11:40:02
Document(s) archivé(s) le : dimanche 7 octobre 2012 - 02:31:29

Fichier

journal.pgen.1002080.pdf
Fichiers éditeurs autorisés sur une archive ouverte

Identifiants

Collections

Citation

Deniz Simsek, Erika Brunet, Sunnie Yan-Wai Wong, Sachin Katyal, Yankun Gao, et al.. DNA ligase III promotes alternative nonhomologous end-joining during chromosomal translocation formation.. PLoS Genetics, Public Library of Science, 2011, 7 (6), pp.e1002080. 〈10.1371/journal.pgen.1002080〉. 〈inserm-00715279〉

Partager

Métriques

Consultations de la notice

261

Téléchargements de fichiers

242