Figure 7.

Induction of apoptosis in TERT/TERC mutants in basal conditions and under oxidative stress. Apoptosis was measured by determination of Annexin V expression and propidium iodide (PI) incorporation by FACS cytometry in VA-13 cells transfected with pBABE empty vector (transfection control), pBABE-WT TERT/TERC (WT telomerase) or the different TERT (panels A, C) and TERC (panels B, D) mutants. 16 h after transfection cells were exposed to a sublethal dose of H₂O₂ (1 mM) for 3 h in panels C and D. Cells were allowed to recover by culture in fresh media overnight. The total number of cells undergoing late apoptosis is represented. The colors of the bars represent the different gene domains in which the mutations are found: yellow (controls: pBABE and pBABE-WT TERT/TERC), light green (TEN: p.Leu55Gln to p.Ala202Thr), light blue (RT: p.Val694Met to p.Arg865Cys), orange (CTE: p.Val1090Met and p.Thr1101Met) for TERT and pink (P1a stem: n.23G>C), purple (t/PK: n.96_97delCT and n.98G>A), dark blue (CR4/5: n.269G>A and n.325G>T) for TERC. Graph bars represent mean values ± SEM of three independent experiments. In each condition of the experiments, 10 000 cells were analyzed. Statistical significance between pBABE-WT TERT/TERC and each TERT or TERC mutant was calculated using a two-tailed unpaired t-test (^*P < 0.05; ^**P < 0.01; ^***P < 0.001).