Growth, Apoptosis and Functional Genomics Analysis of CHO-K1 Over-Expressing Telomerase

Abstract

The enzyme telomerase plays a crucial role in cellular proliferation. By adding hexameric repeats to the chromosome ends, it prevents telomeric loss and, thus entry into senescence of limited life span cells. It is unclear however, what would be the effect of over-expressing telomerase in an immortalised cell line, characterised by unlimited life span and high levels of apoptosis in suboptimal growth conditions. In order to address this question, we have transfected the immortal cell line CHO-K1 with the human telomerase reverse transcriptase (hTERT) catalytic sub-unit. Significant difference in the growth profile and apoptosis levels between the cells over-expressing hTERT (Telo) and the cells containing blank vector was found under standard growth conditions. Similarly the Telo cells showed lower levels of apoptosis, greater attachment tendency and higher viable cell density under serum deprived condition compared to the blank cell line, suggesting a major role for hTERT in stressed cultures. Using a mouse cDNA microarray, the collagen type III and V genes were shown to have at least a 10 fold higher expression in the Telo cells than the control cells.