Poly(ADP-Ribose) Polymerase-1 and DNA-Dependent Protein Kinase Have Equivalent Roles in Double Strand Break Repair Following Ionizing Radiation

Journal Article · Tue Dec 01 04:00:00 EST 2009 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.07.1722· OSTI ID:21367565

Mitchell, Jody ^[1]; Smith, Graeme ^[2]

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1. Northern Institute for Cancer Research, Medical School, Newcastle University, Newcastle upon Tyne (United Kingdom)
2. KuDOS Pharmaceuticals, Cambridge Science Park, Cambridge (United Kingdom)

Purpose: Radiation-induced DNA double strand breaks (DSBs) are predominantly repaired by nonhomologous end joining (NHEJ), involving DNA-dependent protein kinase (DNA-PK). Poly(ADP-ribose) polymerase-1 (PARP-1), well characterized for its role in single strand break repair, may also facilitate DSB repair. We investigated the activation of these enzymes by differing DNA ends and their interaction in the cellular response to ionizing radiation (IR). Methods and Materials: The effect of PARP and DNA-PK inhibitors (KU-0058684 and NU7441) on repair of IR-induced DSBs was investigated in DNA-PK and PARP-1 proficient and deficient cells by measuring gammaH2AX foci and neutral comets. Complementary in vitro enzyme kinetics assays demonstrated the affinities of DNA-PK and PARP-1 for DSBs with varying DNA termini. Results: DNA-PK and PARP-1 both promoted the fast phase of resolution of IR-induced DSBs in cells. Inactivation of both enzymes was not additive, suggesting that PARP-1 and DNA-PK cooperate within the same pathway to promote DSB repair. The affinities of the two enzymes for oligonucleotides with blunt, 3' GGG or 5' GGG overhanging termini were similar and overlapping (K{sub dapp} = 2.6-6.4nM for DNA-PK; 1.7-4.5nM for PARP-1). DNA-PK showed a slightly greater affinity for overhanging DNA and was significantly more efficient when activated by a 5' GGG overhang. PARP-1 had a preference for blunt-ended DNA and required a separate factor for efficient stimulation by a 5' GGG overhang. Conclusion: DNA-PK and PARP-1 are both required in a pathway facilitating the fast phase of DNA DSB repair.

• OSTI ID: 21367565
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 5 Vol. 75; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ADP
ALDEHYDES
CARBOHYDRATES
DNA DAMAGES
ENZYMES
IONIZING RADIATIONS
MONOSACCHARIDES
NUCLEOTIDES
NUCLEOTIDYLTRANSFERASES
ORGANIC COMPOUNDS
PENTOSES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
POLYMERASES
PROTEINS
RADIATIONS
RIBOSE
SACCHARIDES
STRAND BREAKS
TRANSFERASES