The expression of tRNA genes and young Alu subfamilies in human tumor cells U937 during apoptosis

Abstract

Expression of RNA polymerase III-directed genes, tRNAimet1, tRNAHis, and Alu-repeats belonging to the youngest subfamilies AluY (AluYa5 and AluYb8), have been studied in human U937 cells during camptothecin-induced apoptosis. The level of tRNAiMet1 increased 1.5-fold, the tRNAHis level did not change, and the level of AluY-RNA increased fourto ten-fold after 6 h of camptothecin (CAM) treatment compared to control (nonapoptotic) cells. We also studied the level of AluYb8 DNA methylation in apoptotic U937 cells. We have shown that the level of AluYb8 DNA methylation does not change at different stages of apoptosis and does not differ in apoptotic and control cells. We assume that the increase in gene expression of young AluY repeats and tRNAiMet1 is critical for realization of the apoptotic pathways in cells.