FIGURE 1.

Rheb overexpression enhances the rate of cell death in a CAAX-box-dependent manner after toxic treatment. A, primary cortical neurons transfected with FLAG-Rheb-WT exhibited an increased rate of cell death 24 h after excitotoxic treatment with 1 mm glutamate compared with mock-transfected cells. B, in Rheb-WT- but not RhebΔCAAX-transfected HeLa cells, the mTOR pathway was strongly activated as shown by the activation level of the S6 protein on Western blot. C, the size of Rheb-WT-transfected HeLa cells was increased compared with RhebΔCAAX or mock-transfected HeLa cells. D, HeLa cells transfected with FLAG-Rheb-WT were more sensitive to UV light as measured by quantification of apoptotic cells 4 h after UV light treatment (0.03 J/cm²). Notably, the basal level of apoptotic cells did not change upon transfection with FLAG-Rheb-WT or FLAG-RhebΔCAAX. E, HeLa cells transfected with Rheb-WT had significantly higher rates of cell death after TNFα (10 ng/ml + 2.5 μg/ml cycloheximide) treatment compared with RhebΔCAAX or mock-transfected cells. F, ER stress-induced apoptosis in the presence of tunicamycin was increased in Rheb-WT-transfected cells but not in RhebΔCAAX-transfected cells. All bars represent mean ± S.E. of at least six independent experiments. **, p < 0.01; ***; p < 0.001 (determined by ANOVA followed by a Bonferroni post hoc test).