Investigation of switch from ATM to ATR signaling at the sites of DNA damage induced by low and high LET radiation

Janapriya Saha, Minli Wang, Francis A. Cucinotta

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Upon induction of DNA damage by ionizing radiation (IR), members of the phosphatidylinositol 3-kinase-like kinase family of proteins namely ataxia-telangiectasia mutated (ATM), DNA-PKcs, and ATM- and Rad3-related (ATR) maintain genomic integrity by mounting DNA damage response (DDR). Recent reports suggest that activation of ATM and ATR are oppositely regulated by the length of single stranded overhangs generated during end processing by nucleases at the break sites. These stretches of single stranded overhangs hold the clue for the transition from ATM to ATR signaling at broken DNA ends. We investigated whether differential processing of breaks induced by low and high LET radiation augments the phenomenon of switching from ATM to ATR kinase and hence a concomitant NHEJ to HR transition at the sites of DNA damage. 82-6 human fibroblasts were irradiated with 1 or 2Gy of γ-rays and particle radiation of increasing LET in order to increase the complexity and variability of DNA double strand breaks (DSB) structures. The activation kinetics of ATM and ATR kinases along with their downstream substrates were determined utilizing Western blotting and immunofluorescence techniques. Our data provide evidence of a potential switch from ATM to ATR kinase signaling in cells treated with γ-rays at approximately 2h post irradiation, with induction and completion of resection denoted by Rad51 foci resolution kinetics and observed with a significant decline of phosphorylated ATR kinase 8h after IR. On the other hand, irradiation with high LET 600MeV/u 56Fe (180keV/μm) and 170MeV/u 28Si (99keV/μm) particles show a similar Rad51 foci decay kinetics, however, exhibiting prolonged resection, evident by the persistent phosphorylated ATM and ATR kinase until 24h post irradiation. This residual effect, however, was significantly reduced for 250MeV/u 16O particles of moderate LET (25keV/μm) and absent for γ-rays. Hence, our results support the hypothesis that the transition from ATM to ATR signaling at DNA break sites is extended for longer periods of time, indicated by sustained resection due to the complex type of damage induced, a hallmark of high LET radiation, which may contribute to its increased biological effectiveness.

Original languageEnglish (US)
Pages (from-to)1143-1151
Number of pages9
JournalDNA Repair
Volume12
Issue number12
DOIs
StatePublished - Dec 1 2013

Fingerprint

Linear Energy Transfer
Ataxia Telangiectasia
Automatic teller machines
DNA Damage
Switches
Radiation
Phosphotransferases
DNA
Ionizing radiation
Irradiation
Ionizing Radiation
Kinetics
Ataxia Telangiectasia Mutated Proteins
Chemical activation
Phosphatidylinositol 3-Kinase
DNA Breaks
Double-Stranded DNA Breaks
Fibroblasts
Processing
Mountings

Keywords

  • ATM-to-ATR switch
  • DNA repair
  • End processing
  • High LET radiation
  • HZE particles
  • Resection

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Investigation of switch from ATM to ATR signaling at the sites of DNA damage induced by low and high LET radiation. / Saha, Janapriya; Wang, Minli; Cucinotta, Francis A.

In: DNA Repair, Vol. 12, No. 12, 01.12.2013, p. 1143-1151.

Research output: Contribution to journalArticle

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