Induction of Alternative Splicing and Inhibition of Activity of Telomerase Catalytic Subunit by Apoptotic Endonuclease EndoG in Human T, B, and NK Cells

The effect of apoptotic endonuclease EndoG on alternative splicing of mRNA of human telomerase catalytic subunit hTERT (human telomerase reverse transcriptase) and telomerase activity in normal human lymphocytes were studied. Human CD4(+), CD8(+), B, and NK cells were transfected with a plasmid pEndoG-GFP containing EndoG gene or control plasmid pGFP. The levels of mRNA of EndoG or hTERT splicing variants were analyzed by real-time PCR. Protein content was assessed by Western blotting. Telomerase activity was measured by the telomere repeats amplification protocol. EndoG overexpression reduced the expression of active full-length hTERT and increased the expression of inactive splice variant. Shifted balance of hTERT splice variants in cells led to a significant decrease in telomerase activity within 72 h after transfection.