Adaptive Changes in Human Leukocytes in Response to a Long-Term Stay in Antarctica

Abstract

Oxidative stress and aging are known to alter the copy number (CN) of satellite III repeat (1q12) (SatIII(1q)) and telomeric repeat (TR) in the DNA of human cells. The extreme conditions of Antarctica could potentially affect the CN of these repeats in human blood cells, which may be associated with inhibition of the antioxidant system and activation of apoptosis. In this work, we analyzed the CN of ribosomal DNA (rDNA), SatIII(1q), and TR repeats in the leukocytes of 11 male members of the expedition to Vostok station in 2019–2020. To observe dynamic changes in the number of repeating elements of the genome and the degree of their oxidation, six blood samples were taken: before arrival in Antarctica, after 27, 85, 160, 270, and 315 days of wintering. To analyze adaptive changes, the expression levels of the BAX, BCL2, NOX4, NRF2, SOD1, and HIF1 genes were measured. We detected a decrease in SatIII(1q) CN and an increase in TR CN against the background of a stable rDNA CN in human blood cells during wintering. These changes, along with a decrease in the 8-oxodG in DNA, are associated with an increase in the activity of the NOX4 gene, a decrease in the activity of the NRF2 gene, and an increase in the expression of the proapoptotic protein BAX. Thus, wintering in Antarctica stimulates an adaptive response in the human body, which includes increased elimination from the bloodstream of “ballast” cells with a high level of DNA oxidation, a high SatIII(1q) content, and a low TR content. An increase in ROS levels due to chronic activation of the NOX4 gene along with the blocked NRF2 gene may play a significant role in the development of the response.