DNA Methylation in Mouse Spermatozoa under Long-Term Modeling the Effects of Microgravity

Abstract

The mechanisms of the interaction between cells and the gravitational field are still unknown, and there are hardly any data on the effect of the gravity force on the germ cells. The objective of this work was to determine the expression levels of the genes encoding cytoskeletal proteins (beta- and gamma-actin, actin-binding proteins alpha-actinin-1 and alpha-actinin-4, beta-tubulin, and desmin) by quantitative PCR, the local level (CpG-island promoter regions of the studied genes) and the total methylation level by the restriction analysis, the content of 5-hydroxymethylcytosine by the dot blotting method, as well as the content of enzymes ensuring the establishment/maintenance of the appropriate level of methylation by the Western blotting method, in the spermatozoa of mice that were subjected for 30 days to antiorthostatic suspension and subsequent 12-h recovery. We also administrated mice with essential phospholipids (per os) and determined the parameters described above. The results suggest that antiorthostatic suspension did not lead to significant changes in the expression level of the genes encoding the actin cytoskeleton proteins in sperm; however, after 12 h of recovery, their expression increased. At the same time, the methylation of CpG islands in the promoter regions of these genes decreased. Oral administration of essential phospholipids equalized these changes. The beta-tubulin gene expression decreased after suspension, and neither the 12-h recovery nor the administration of essential phospholipids changed the situation. In general, the overall methylation level was reduced only in the 12-h recovery group, correlating with an increase in the expression level of the studied genes. At the same time, the content of methylase/demethylase did not change; however, the content of histone acetylase increased, suggesting that, under modeling microgravity conditions, the processes of chromatin modification may be involved in the change in gene expression.