Time-Dependent Induction of the Nucleotide Excision Repair Gene XPA and RAD۵۱ in Homologous Recombination in Human Lymphocytes Exposed to Low Doses of Ionizing Radiation

Introduction: The aim of the present study was to understand the effect of low-doses of ionizing radiation (LDIR) on repair genes expression in blood samples that were taken from healthy donors. The next purpose was to examine the time-effect on the modified gene expression caused by low-doses of ionizing radiation.Material and Methods: The RNA of peripheral blood lymphocytes (PBLs) taken from four healthy donors was isolated at different time points after exposure including ۴, ۲۴, ۴۸, ۷۲, and ۱۶۸ hours and then cDNA was synthesized. Modification of XPA and RAD۵۱ expression levels due to LDIR (۲, ۵, ۱۰ cGy) were evaluated by relative quantitative reverse transcription-polymerase chain reaction.Results: Significant up-regulation of both repair genes was observed at the ۴ and ۱۶۸ h following to ۱۰ cGy.  Also, this dose could increase expression levels of RAD۵۱ at ۴۸ and ۷۲ h after radiation. For lower doses at ۵ cGy, only XPA levels were significantly up-regulated after ۱۶۸ h. A significant regression was found between the XPA levels and the dose, at ۱۶۸ h after irradiation to PBLs that can represent a new potential biomarker for biological dosimetry purposes.Conclusion: The results of this study could support the hypothetical role of the different DNA repair pathways in response to LDIR. This led us to propose a molecular biodosimetry method for ionizing radiation in the range of LDIR.

Keywords:

DNA damage , Gene expression , Ionizing radiation , XPA , RAD۵۱