Fig. 3. Telomerase is excluded from the nucleus under oxidative stress and colocalises with mitochondria. (A) Percentage of total TRAP activity in the extranuclear fraction of MRC5-TERT after H₂O₂. (B) Percentage of total TRAP activity in the extranuclear fraction following hyperoxic treatment for the indicated times. Data are mean±s.e.m. from three independent experiments. (C) Change in mitochondrial (white) and nuclear (black) TRAP activity after 3 hours of 500 mM H₂O₂ exposure or 52 days of hyperoxia. Data are mean±s.e.m. from six replicate measurements. All values are significantly different from controls (100%). (D-G) TERT immunofluorescence (red) in MRC5-TERT under normoxia (D, left), following treatment with H₂O₂ at the indicated concentrations (D, middle and right), under hyperoxia for the indicated times (E), in cells grown under hyperoxia for 50 days followed by shift back to normoxia for the indicated times (F), and co-stained after 70 days hyperoxia with Mitotracker green (G). Colocalisation of mitochondria and TERT-containing foci appears in yellow.