Evaluation of the role of mitochondria in the non-targeted effects of ionizing radiation using cybrid cellular models

Abstract

Radiobiology is moving towards a better understanding of the intercellular signaling that occurs upon radiation and how its effects relate to the dose applied. The mitochondrial role in orchestrating this biological response needs to be further explored. Cybrids (cytoplasmic hybrids) are useful cell models for studying the involvement of mitochondria in cellular processes. In the present study we used cybrid cell lines to investigate the role of mitochondria in the response to radiation exposure. Cybrid cell lines, derived from the osteosarcoma human cell line 143B, harboring, either wild-type mitochondrial DNA (Cy143Bwt), cells with mitochondria with mutated DNA that causes mitochondrial dysfunction (Cy143Bmut), as well as cells without mitochondrial DNA (mtDNA) (143B-Rho0), were irradiated with 0.2 Gy and 2.0 Gy. Evaluation of the non-targeted (or bystander) effects in non-irradiated cells were assessed by using conditioned media from the irradiated cells. DNA double stranded breaks were assessed with the γH2AX assay. Both directly irradiated cells and cells treated with the conditioned media, showed increased DNA damage. The effect of the irradiated cells media was different according to the cell line it derived from: from Cy143Bwt cells irradiated with 0.2 Gy (low dose) and from Cy143Bmut irradiated with 2.0 Gy (high dose) induced highest DNA damage. Notably, media obtained from cells without mtDNA, the143B-Rho0 cell line, produced no effect in DNA damage. These results point to a possible role of mitochondria in the radiation-induced non-targeted effects. Furthermore, it indicates that cybrid models are valuable tools for radiobiological studies.

Cytosolic Release of Mitochondrial DNA and Associated cGAS Signaling Mediates Radiation-Induced Hematopoietic Injury of Mice

“…In fact, the early concept of a side effect stems from the increase of ROS in the mitochondrial pathway, which triggers complex intra- and intercellular signaling cascade reactions, leading to cell DNA damage, gene mutation, and other forms of radiation that mimic biological effects [ 10 , 11 , 12 ]. In addition, mitochondria are also the only place where DNA exists outside the nucleus.…”

Amelioration of Radiation-Induced Cell Death in Neuro2a Cells by Neutralizing Oxidative Stress and Reducing Mitochondrial Dysfunction Using N-Acetyl-L-Tryptophan

“…These observations suggested that L-NAT treatment may efficiently reduce ROS and thus inhibit oxidative stress in irradiated cells. Ionizing radiation-induced oxidative stress causes hypo/hyperpolarization of the mitochondrial membrane that promotes the leakage of radicals and thus activates mitochondrial oxidative stress and intrinsic apoptosis pathways [ 45 ]. L-NAT pretreatment, however, was observed to reduce the hyperpolarization of the mitochondrial membrane in Neuro2a cells exposed to radiation ( Figure 8 ), possibly by reducing reactive oxygen species in the cellular milieu or preventing the accumulation of cytoplasmic Ca 2+ in the mitochondrial matrix.…”

Low Dose and Non-Targeted Radiation Effects in Environmental Protection and Medicine—A New Model Focusing on Electromagnetic Signaling

“…These in turn are attributed to DNA damage, elevated ROS, mitochondrial insufficiency, membrane channel imbalances and failure of “checks and balances” on the rate of specific enzyme reactions, leading to tipping points where metabolic malfunction occurs. In particular, energy production and utilisation by cells is altered [ 16 , 97 , 98 ]. The energy deposition from low dose radiation and the consequent electromagnetic emissions in the form of light and acoustic signals, can thus be linked with gross outcomes in a way where system level modelling may be applied.…”