Archives → 2018 → Vol. 58, No. 6 → pp. 589-596
Article
Evaluation of Contribution of Homologous Recombination in DNA Double-Strand Break Repair in Human Fibroblasts after Exposure to Low and Intermediate Doses of X-Ray Radiation
Grekhova A.K.1,2,3, Pustovalova M.V.2,3, Eremin P.S.4, Ozerov I.V.2, Maksimova O.A.2, Gordeev A.V.2, Vorobyeva N. Yu.2,3, Osipov A.N.2,3
1 N.M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia. 2 State Research Center – Burnasyan Federal Medical Biophysical Center of Federal Medical Biological Agency, Moscow, Russia. 3 Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow, Russia. 4 Federal State Budgetary Institution «National Medical Research Center of Rehabilitation and Balneology» of the Ministry of Healthcare of the Russian Federation, 32, Novy Arbat Street, Moscow, 121099, Moscow.
Abstract
Studies of the changes in the number of γH2AX foci (DNA double-strand break protein-marker), and Rad51 foci (key homologous recombination protein) were conducted on the culture of human fibroblasts within 24 hours after exposure to low (80 mGy) and intermediate (250 and 1000 mGy) doses of X-ray irradiation. Based on the obtained data, exponential curves that approximated experimental values were constructed, and the characteristic lifetime of the γH2AX and Rad51 foci was evaluated using the method of least squares. The ratio of the areas under the curves of changes in the number of Rad51 and γH2AX foci, calculated by the trapezium method, divided by the ratio of the characteristic lifetimes of the Rad51 and H2AX foci was used to evaluate the contribution of homologous recombination in the DNA double-strand break repair. It was shown that the contribution of homologous recombination in the DNA double-strand break repair within 24 hours after exposure to 80, 250 and 1000 mGy was approximately 16, 12 and 9% respectively. Thus, relative contribution of homologous recombination in the DNA double-strand break repair after exposure to low dose of X-ray irradiation was approximately 1.5 times higher than that after exposure to intermediate doses. Our results suggest that repair of DNA double-strand breaks induced after exposure to 80 mGy of X-ray irradiation should be more correct than after exposure to 250 and 1000 mGy.
Keywords
DNA double-strand breaks, homologous recombination, fibroblasts, X-ray radiation, low doses
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