Figure 5.

Ectopic expression of ATF4 sensitizes neurons to ER-stress-induced but not DNA-damage-induced apoptosis. A, Cortical neurons were cotransfected with pGFP and either pcDNA3 [empty vector (EV)] or pcDNA3–ATF4, and, after 24 h, neurons were treated with camptothecin (10 μm), tunicamycin (2 μg/ml), or DMSO (0.1%) as a vehicle control. At the indicated times, neurons were fixed and stained with Hoechst 33258, and the fraction of apoptotic and nonapoptotic GFP-positive cells was assessed by fluorescence microscopy (n = 3; *p < 0.05). B, Cortical neurons were infected with recombinant adenovirus expressing GFP (Ad–GFP) or coexpressing ATF4 and GFP (Ad–ATF4/GFP) at 50 MOI and, after 48 h, treated with tunicamycin (2 μg/ml) or thapsigargin (1 μm). After 24 h, cells were fixed and stained with Hoechst 33258, and the fraction of apoptotic and nonapoptotic GFP-positive neurons was determined (n = 3; **p < 0.01).