Altered mitochondrial function and genome frequency post exposure to γ-radiation and bystander factors

Sharon Nugent, Carmel E. Mothersill, Colin Seymour, Brendan McClean, Fiona M. Lyng, James E.J. Murphy

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)

Abstract

Purpose:To further evaluate irregular mitochondrial function and mitochondrial genome damage induced by direct γ-irradiation and bystander factors in human keratinocyte (HPV-G) epithelial cells and hamster ovarian fibroblast (CHO-K1) cells. This is as a follow-up to our recent reports of γ-irradiation-induced loss of mitochondrial function and mitochondrial DNA (mtDNA) damage. Materials and methods:Mitochondrial function was evaluated post direct radiation and irradiated cell conditioned medium (ICCM) by determining: Activity of the individual complexes of oxidative phosphorylation (OxPhos); mtDNA-encoded protein synthesis; and mitochondrial genome frequency and mtDNA damage. Results:Mitochondria show a loss of OxPhos enzyme function as early as 4h post treatment with recovery observed 1296h in some but not all complexes demonstrating a non-uniform sensitivity to γ-radiation. We also identified irregular mtDNA-directed protein synthesis. Long range Polymerase Chain Reaction (PCR) analysis identified mitochondrial genome damage and real-time PCR identified increases in mitochondrial genome frequency. Conclusions:The study reaffirms the sensitive nature of mitochondria to both low-level direct radiation exposure and radiation-induced bystander factor mediated damage. Furthermore, we report for the first time, the loss of function in the enzymes of OxPhos post exposure to bystander factors and identify altered mtDNA-directed protein synthesis post both direct radiation and bystander factors.

Original languageEnglish
Pages (from-to)829-841
Number of pages13
JournalInternational Journal of Radiation Biology
Volume86
Issue number10
DOIs
Publication statusPublished - Oct 2010

Keywords

  • bystander
  • ionising radiation
  • mitochondrial DNA
  • oxidative phosphorylation

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