Radiation response of chemically derived mitochondrial DNA-deficient AG01522 human primary fibroblasts

D. Nieri, M. Fioramonti, F. Berardinelli, S. Leone, R. Cherubini, V. De Nadal, S. Gerardi, S. Moreno, R. Nardacci, C. Tanzarella, A. Antoccia

Research output: Contribution to journalArticle

Abstract

Mitochondria are the main cellular source of Reactive Oxygen Species (ROS). Alterations of mitochondrial metabolism and consequent loss of mitochondrial membrane potential may lead to redox imbalance and in turn to DNA damage, chromosomal instability and apoptosis. On the other hand, impaired mitochondrial functions may either exacerbate the detrimental effects of geno- and cytotoxic agents or may bring beneficial cellular responses. To study the role of mitochondria within this framework, AG01522 human primary fibroblasts were incubated with the mitochondrial polymerase γ inhibitor 2',3'-dideoxycytidine (ddC), leading to mitochondrial DNA (mtDNA) depletion and to mitochondrial dysfunctions. The successful treatment toward mtDNA depletion was confirmed by Complex-IV subunit I (COX-I) immunofluorescence and western blot assays. mtDNA-depleted cells and their counterparts were ultrastructurally characterized by transmission electron microscopy. mtDNA-depleted cells showed dramatic mitochondrial alterations such as fragmentation and cristae disruption along with a reduction of the mitochondrial membrane potential and elevated levels of ROS. Despite increased ROS levels, we did not find any difference in telomere length between ddC-treated and untreated cells. The spontaneous rate of DNA double-strand breaks (DSBs) and chromosome aberrations was significantly enhanced in mtDNA-depleted cells whereas the induction of DSBs by low-Linear Energy Transfer (LET) (X-rays; 7.7. keV/μm protons) and high-LET radiations (28.5. keV/μm protons) did not differ when compared with normal cells. However, in irradiated cells impaired mitochondrial functions seemed to bring beneficial cellular responses to the detrimental effect of radiations. In fact, after X-irradiation mtDNA-depleted cells show less remaining unrejoined DSBs than normal cells and furthermore a lower induction of cytogenetic damage. Overall, these data show that active mitochondrial functions are required for the proper maintenance of cellular genome stability in primary fibroblasts.

Original languageEnglish
Pages (from-to)86-94
Number of pages9
JournalMutation Research - Genetic Toxicology and Environmental Mutagenesis
Volume756
Issue number1-2
DOIs
Publication statusPublished - May 30 2013

Keywords

  • Cytogenetic damage
  • Human primary fibroblasts
  • Ionizing radiations
  • Mitochondria
  • Mitochondrial fragmentation
  • ROS

ASJC Scopus subject areas

  • Health, Toxicology and Mutagenesis
  • Genetics

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    Nieri, D., Fioramonti, M., Berardinelli, F., Leone, S., Cherubini, R., De Nadal, V., Gerardi, S., Moreno, S., Nardacci, R., Tanzarella, C., & Antoccia, A. (2013). Radiation response of chemically derived mitochondrial DNA-deficient AG01522 human primary fibroblasts. Mutation Research - Genetic Toxicology and Environmental Mutagenesis, 756(1-2), 86-94. https://doi.org/10.1016/j.mrgentox.2013.05.010