Characterization of novel alternative splicing sites in human telomerase reverse transcriptase (hTERT): analysis of expression and mutual correlation in mRNA isoforms from normal and tumour tissues.
BACKGROUND
Human telomerase reverse transcriptase (hTERT) is a key component for synthesis and maintenance of telomeres on chromosome ends and is required for the continued proliferation of cells. Estimation of hTERT expression therefore has broad relevance in oncology and stem cell research. Several splicing variants of hTERT have been described whose regulated expression contributes to the control of telomerase activity. Knowledge of the different hTERT mRNA isoforms and the ability to distinguish between them is an important issue when evaluating telomerase expression.


RESULTS
By establishing cDNA-clone panels from lung and colon tissues, we could map hTERT clones individually for differences in DNA sequence. This made possible the identification of novel alternatively spliced sites as well as analysis of their frequency and mutual correlation in mRNA isoforms. Ten different alternatively spliced sites were detected, of which six were novel sites resulting from alternative splicing of intron 2 or 14. The majority of hTERT cDNA clones from normal and tumour lung and colon tissues encoded truncated proteins ending close after exon 2 or 6.


CONCLUSIONS
The increased complexity in telomerase expression revealed here has implications for our understanding of telomerase regulation and for the choice of suitable methods for addressing hTERT expression.
Saebøe-Larssen
Stein
S
Section for Immunotherapy, Department of Immunology, The Norwegian Radium Hospital, Cancer Research Institute, University of Oslo, N-0310 Oslo, Norway. steinsl@ulrik.uio.no
Fossberg
Ellen
E
Gaudernack
Gustav
G
D017398:Alternative Splicing / Q000235:genetics*; D003106:Colon / Q000378:metabolism; D003110:Colonic Neoplasms / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics*; D005091:Exons / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020014:K562 Cells; D008168:Lung / Q000378:metabolism; D008175:Lung Neoplasms / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D019098:Telomerase / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D019098:Telomerase