Electronic Thesis and Dissertation Repository


Master of Science




Dr. Dean H. Betts


Recent evidence points to extra-telomeric roles of telomerase in regulating stem cell function. In this study, human embryonic stem cells (hESCs) were cultured in 20% or 2% oxygen for up to 5 days and evaluated for telomerase reverse transcriptase (TERT) expression and telomerase activity. Results showed increased cell survival and maintenance of the undifferentiated state with elevated levels of nuclear TERT in 2% oxygen cultured hESCs despite no significant difference in telomerase activity. Pharmacological inhibition of TERT caused spontaneous differentiation while inhibition of the telomerase RNA component (TERC) did not. RT-PCR analysis revealed variations in transcript levels of full-length and alternate splice variants of TERT. Morpholino oligonucleotides that block specific pre-mRNA TERT splicing events induced spontaneous hESC differentiation. Together these results suggest that post-transcriptional regulation of TERT under low oxygen could be a selective advantage for hESC survival and maintenance of the undifferentiated state by extra-telomeric telomerase isoforms.