UVI-induced endogenous retrovirus HERV-E λ 4-1 expression in blood mononuclear cells

Abstract

The influence of various environmental factors indirectly, through the epigenetic mechanisms of regulation of gene expression, can lead to the activation of human endogenous retroviruses. The purpose of this study was to investigate the possibility of activation of the first class HERV-E λ 4-1 (ER λ 4-1) endogenous retrovirus as a result of exposure to UV radiation in vitro. Materials and methods. Blood mononuclear cells (MNCs) of conditionally healthy individuals in a concentration of 20 x 106/ml were exposed to UV irradiation for 5 minutes on an ultraviolet radiator at a wavelength of 340 nm and a radiation intensity of 50 W/m2 in vitro. After irradiation, the cell samples were cultured for 24 hours in a complete culture medium in a CO2 incubator. Then, in these cell culture samples the proliferative activity, based on the incorporation of tritium labeled thymidine, a viability, by the trypan blue staining, and ER-E λ 4-1 expression by the reverse transcriptase polymerase chain reaction method, were determined. The main results. UV irradiation of mononuclear cell cultures for 5 minutes did not leads to the changes in their viability and functional activity. The study of the of the env ER λ 4-1 gene expression frequency in the MNC of donor’s blood before and after the exposure to UV radiation revealed the differences in this index. Thus, before the exposure to UV radiation, the expression rate of env ER-λ 4-1 was 4.4% (2/45), whereas after the irradiation its expression was determined much more often 24% (11/45). Along with an increase in the expression frequency, an augmentation in the mRNA level of the env gene ER-λ 4-1 was also observed. Conclusion. Thus, the exposure to ultraviolet radiation with the intensity of 50 W/m2 for 5 minutes on blood mononuclear cells of conditionally healthy individuals in vitro leads to activation of the human endogenous retrovirus HERV-E λ 4-1: an increase of its expression frequency and the level of mRNA.