Homologous recombination repairs secondary replication induced DNA double-strand breaks after ionizing radiation

Petra Groth, Manuel Luis Orta, Ingegerd Elvers, Muntasir Mamun Majumder, Anne Lagerqvist, Thomas Helleday

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Ionizing radiation (IR) produces direct two-ended DNA double-strand breaks (DSBs) primarily repaired by non-homologous end joining (NHEJ). It is, however, well established that homologous recombination (HR) is induced and required for repair of a subset of DSBs formed following IR. Here, we find that HR induced by IR is drastically reduced when post-DNA damage replication is inhibited in mammalian cells. Both IR-induced RAD51 foci and HR events in the hprt gene are reduced in the presence of replication polymerase inhibitor aphidicolin (APH). Interestingly, we also detect reduced IR-induced toxicity in HR deficient cells when inhibiting post-DNA damage replication. When studying DSB formation following IR exposure, we find that apart from the direct DSBs the treatment also triggers formation of secondary DSBs peaking at 7-9 h after exposure. These secondary DSBs are restricted to newly replicated DNA and abolished by inhibiting post-DNA damage replication. Further, we find that IR-induced RAD51 foci are decreased by APH only in cells replicating at the time of IR exposure, suggesting distinct differences between IR-induced HR in S- and G2-phases of the cell cycle. Altogether, our data indicate that secondary replication-associated DSBs formed following exposure to IR are major substrates for IR-induced HR repair.
Original languageEnglish
JournalNucleic Acids Research
Volume40
Issue number14
Pages (from-to)6585-94
Number of pages10
ISSN0305-1048
DOIs
Publication statusPublished - 2012
Externally publishedYes
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 3111 Biomedicine

Cite this

Groth, Petra ; Luis Orta, Manuel ; Elvers, Ingegerd ; Majumder, Muntasir Mamun ; Lagerqvist, Anne ; Helleday, Thomas. / Homologous recombination repairs secondary replication induced DNA double-strand breaks after ionizing radiation. In: Nucleic Acids Research. 2012 ; Vol. 40, No. 14. pp. 6585-94.
@article{a7a98f868c964d98931c66f9dd5a0f22,
title = "Homologous recombination repairs secondary replication induced DNA double-strand breaks after ionizing radiation",
abstract = "Ionizing radiation (IR) produces direct two-ended DNA double-strand breaks (DSBs) primarily repaired by non-homologous end joining (NHEJ). It is, however, well established that homologous recombination (HR) is induced and required for repair of a subset of DSBs formed following IR. Here, we find that HR induced by IR is drastically reduced when post-DNA damage replication is inhibited in mammalian cells. Both IR-induced RAD51 foci and HR events in the hprt gene are reduced in the presence of replication polymerase inhibitor aphidicolin (APH). Interestingly, we also detect reduced IR-induced toxicity in HR deficient cells when inhibiting post-DNA damage replication. When studying DSB formation following IR exposure, we find that apart from the direct DSBs the treatment also triggers formation of secondary DSBs peaking at 7-9 h after exposure. These secondary DSBs are restricted to newly replicated DNA and abolished by inhibiting post-DNA damage replication. Further, we find that IR-induced RAD51 foci are decreased by APH only in cells replicating at the time of IR exposure, suggesting distinct differences between IR-induced HR in S- and G2-phases of the cell cycle. Altogether, our data indicate that secondary replication-associated DSBs formed following exposure to IR are major substrates for IR-induced HR repair.",
keywords = "3111 Biomedicine",
author = "Petra Groth and {Luis Orta}, Manuel and Ingegerd Elvers and Majumder, {Muntasir Mamun} and Anne Lagerqvist and Thomas Helleday",
year = "2012",
doi = "10.1093/nar/gks315",
language = "English",
volume = "40",
pages = "6585--94",
journal = "Nucleic Acids Research",
issn = "0305-1048",
publisher = "Oxford University Press",
number = "14",

}

Homologous recombination repairs secondary replication induced DNA double-strand breaks after ionizing radiation. / Groth, Petra; Luis Orta, Manuel; Elvers, Ingegerd; Majumder, Muntasir Mamun; Lagerqvist, Anne; Helleday, Thomas.

In: Nucleic Acids Research, Vol. 40, No. 14, 2012, p. 6585-94.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Homologous recombination repairs secondary replication induced DNA double-strand breaks after ionizing radiation

AU - Groth, Petra

AU - Luis Orta, Manuel

AU - Elvers, Ingegerd

AU - Majumder, Muntasir Mamun

AU - Lagerqvist, Anne

AU - Helleday, Thomas

PY - 2012

Y1 - 2012

N2 - Ionizing radiation (IR) produces direct two-ended DNA double-strand breaks (DSBs) primarily repaired by non-homologous end joining (NHEJ). It is, however, well established that homologous recombination (HR) is induced and required for repair of a subset of DSBs formed following IR. Here, we find that HR induced by IR is drastically reduced when post-DNA damage replication is inhibited in mammalian cells. Both IR-induced RAD51 foci and HR events in the hprt gene are reduced in the presence of replication polymerase inhibitor aphidicolin (APH). Interestingly, we also detect reduced IR-induced toxicity in HR deficient cells when inhibiting post-DNA damage replication. When studying DSB formation following IR exposure, we find that apart from the direct DSBs the treatment also triggers formation of secondary DSBs peaking at 7-9 h after exposure. These secondary DSBs are restricted to newly replicated DNA and abolished by inhibiting post-DNA damage replication. Further, we find that IR-induced RAD51 foci are decreased by APH only in cells replicating at the time of IR exposure, suggesting distinct differences between IR-induced HR in S- and G2-phases of the cell cycle. Altogether, our data indicate that secondary replication-associated DSBs formed following exposure to IR are major substrates for IR-induced HR repair.

AB - Ionizing radiation (IR) produces direct two-ended DNA double-strand breaks (DSBs) primarily repaired by non-homologous end joining (NHEJ). It is, however, well established that homologous recombination (HR) is induced and required for repair of a subset of DSBs formed following IR. Here, we find that HR induced by IR is drastically reduced when post-DNA damage replication is inhibited in mammalian cells. Both IR-induced RAD51 foci and HR events in the hprt gene are reduced in the presence of replication polymerase inhibitor aphidicolin (APH). Interestingly, we also detect reduced IR-induced toxicity in HR deficient cells when inhibiting post-DNA damage replication. When studying DSB formation following IR exposure, we find that apart from the direct DSBs the treatment also triggers formation of secondary DSBs peaking at 7-9 h after exposure. These secondary DSBs are restricted to newly replicated DNA and abolished by inhibiting post-DNA damage replication. Further, we find that IR-induced RAD51 foci are decreased by APH only in cells replicating at the time of IR exposure, suggesting distinct differences between IR-induced HR in S- and G2-phases of the cell cycle. Altogether, our data indicate that secondary replication-associated DSBs formed following exposure to IR are major substrates for IR-induced HR repair.

KW - 3111 Biomedicine

U2 - 10.1093/nar/gks315

DO - 10.1093/nar/gks315

M3 - Article

VL - 40

SP - 6585

EP - 6594

JO - Nucleic Acids Research

JF - Nucleic Acids Research

SN - 0305-1048

IS - 14

ER -