Human normal T lymphocytes and lymphoid cell lines do express alternative splicing variants of human telomerase reverse transcriptase (hTERT) mRNA.

Alternative splicing of telomerase reverse transcriptase (hTERT) mRNA is known to contribute to regulation of telomerase activity in normal and cancerous cells, however, previous studies indicated that normal human T and B cells exhibited constitutive expression of full-length hTERT mRNA without splicing variants and that activation of telomerase upon stimulation of the cells was due to the shuttling of hTERT protein from cytoplasm to nucleus [Proc. Natl. Acad. Sci. USA 96 (1999) 5147; J. Immunol. 166 (2001) 4826]. We found that typical variants of hTERT mRNA were widespread in human lymphocyte-derived cell lines and normal stimulated T cells. In activated T cells, induction of the full-length hTERT mRNA was coupled with increased hTERT protein expression and telomerase activity. Collectively, human normal and malignant lymphocytes, like other human cells, express splicing variants of hTERT mRNA and require transcriptional activation of the hTERT gene to acquire telomerase activity.