Figure 6.

Neurons lacking TERT have an increased susceptibility to oxidative stress. A, Cultured neurons were exposed to hydrogen peroxide, and the production of superoxide was measured using DHE. DHE levels were increased in TERT^−/− neurons exposed to hydrogen peroxide compared with control. *p < 0.05 (two-sample t test). Data are mean ± SEM from three independent experiments. ns, Not significant. B, Oxidative stress increases mitochondrial localization of TERT in cultured neurons. *p < 0.05 (two-sample t test). Wild-type neurons were exposed to hydrogen peroxide and analyzed for colocalization between TERT and MTCO1 or TERT and the nuclear stain, DAPI. Data are mean ± SEM from three independent experiments. C, Representative images showing TERT and MTCO1 immunofluorescent labeling of neurons in culture. White arrowheads indicate regions of colocalization. White arrows indicate absence of colocalization. Inset, 2× magnification. D, Immunofluorescent labeling of cultured neurons with calnexin (red) and TERT (green) shows that the majority of TERT does not colocalize with endoplasmic reticulum. Scale bars, 50 μm. E, Representative Western blot showing specific bands for TERT and the mitochondrial protein porin in cultured neurons, transduced with vector control, truncated tau, or mutated tau. F, Quantification of Western blot shows no differences in level of TERT protein between groups (n = 4). G, Quantification of Western blot shows no differences in the level of porin protein expression between groups. Data are mean ± SEM from four independent experiments, analyzed using one-way ANOVA.