Figure 7.

Telomerase protects NPCs against telomere and DNA damage. A, NPCs from TERT^−/− mice lack telomerase activity. TRAP assay analysis of telomerase activity in lysates (150 ng) of cortical neurosphere cultures from E12 wild-type (WT) and TERT knock-out (TERT^−/−) mice. As negative controls, the cell lysates (750 ng) were incubated for 10 min at 85°C. HeLa cell lysate (75 ng) was used as a positive control. B, C, TERT^−/− NPCs are significantly more vulnerable to telomere and DNA damage. Four hours after plating on poly-l-lysine-coated coverslips, wild-type and TERT^−/− neurospheres were treated with TMS (2 μm), etoposide (ET; 10 μm), or camptothecin (CT; 10 μm) for 24 h. Cell death was quantified by counting cells with condensed nuclei in acquired images by confocal laser scanning microscopy after Hoechst staining. Values are the mean ± SD of three independent experiments. **p < 0.001, paired Student's t test.