Effect of Low-Dose Ionizing Radiation on the Expression of Mitochondria-Related Genes in Human Mesenchymal Stem Cells

Abstract

The concept of hormesis describes a phenomenon of adaptive response to low-dose ionizing radiation (LDIR). Similarly, the concept of mitohormesis states that the adaptive program in mitochondria is activated in response to minor stress effects. The mechanisms of hormesis effects are not clear, but it is assumed that they can be mediated by reactive oxygen species. Here, we studied effects of LDIR on mitochondria in mesenchymal stem cells. We have found that X-ray radiation at a dose of 10 cGy as well as oxidized fragments of cell-free DNA (cfDNA) at a concentration of 50 ng/mL resulted in an increased expression of a large number of genes regulating the function of the mitochondrial respiratory chain complexes in human mesenchymal stem cells (MSC). Several genes remained upregulated within hours after the exposure. Both X-ray radiation and oxidized cfDNA resulted in upregulation of FIS1 and MFN1 genes, which regulated fusion and fission of mitochondria, within 3–24 h after the exposure. Three hours after the exposure, the number of copies of mitochondrial DNA in cells had increased. These findings support the hypothesis that assumes oxidized cell-free DNA as a mediator of MSC response to low doses of radiation.

Low-Dose Gamma Radiation Modulates Liver and Testis Tissues Response to Acute Whole Body Irradiation

“…From the beneficial effects observed after low doses (.01–.5 Gy) of gamma radiation are induction of adaptive responses, 6 enhancement of antioxidant defense, 7 increase resistance to high dose of radiation, 8 activation of mitochondrial dynamics, and upregulation of genes controlling respiratory chain. 9 , 10 Feinendegen 2016 summarized the results of several studies investigating the effects of acute low-doses radiation at the molecular and cellular levels, and attempted to quantify adaptive radioprotections. He reported that this protection may reach 100% at doses below 100 mGy while above 200 mGy, the average degree of protection diminishes and may reach about 10%.…”

The Role of Mitochondrial miRNAs in the Development of Radon-Induced Lung Cancer

“…The irradiation of cells stimulates mitochondria to increase the production of ROS [ 24 ]; therefore, it is mtDNA that is the closest target for their action. Previously, it was argued that mitochondria lack mtDNA repair mechanisms but recent studies report their presence [ 25 ].…”