Figure 8.

Nuclear inhibition of Cdk5 does not protect from DNA damage, but cytoplasmic inhibition of Cdk5 sensitizes to DNA damage. Cortical neuron cultures plated 24–36 h before were infected with adenoviral constructs expressing GFP, DN-NLS, or DN-NES at a multiplicity of infection of 75. Two days later, neurons were treated with camptothecin for 14 h. Cultures were immunostained for MAP2, and nuclei were labeled with Hoescht. GFP-expressing MAP2-positive cells were classified as either dead or alive according to the appearance of Hoescht. The ratio of live to total cells counted was used as a measure of survival. Error bars represent the mean ± SEM for data from three independent experiments each done in triplicate. *p < 0.05 by ANOVA. A minimum of 150 cells were counted per well (450 cells per experiment). Infected cultures not treated with camptothecin showed low toxicity (>85% survival for all constructs).