Fig. 4.

Altered apoptotic responses in corticohippocampal neurons lacking RhoB. (A) TUNEL staining in primary cortico-hippocampal cultures from WT (left panels) and RhoB KO (right panels) mice, treated for 24 h with either 100 nm (upper panels) or 500 nm (lower panels) STS. Note the reduced numbers of TUNEL-positive nuclei in the neurons lacking RhoB. Scale bar = 50 µm. (B) TUNEL staining in primary cortical cultures from WT and RhoB KO mice, treated for 24 h with STS at the doses shown. Results are shown as mean ± SEM, n = 5 per group. Two-way anova: effect of STS concentration – F_4,49 = 74.98, P < 0.001; effect of genotype – F_1,49 = 101.10, P < 0.001; *P < 0.05, **P < 0.01; post-hoc Tukey’s test. (C) Caspase 3 activity in primary cortico-hippocampal cultures from WT and RhoB KO mice, treated for 6 h with STS at the concentrations shown; n = 4–6 per group. Note that the selective caspase 3 inhibitor Ac-DMQD-CHO completely inhibits cleavage of the fluorogenic substrate. Two-way anova: effect of STS concentration – F_4,52 = 4.2, P < 0.001; effect of genotype – F_1,52 = 12.87, P < 0.001. (D) Neuronal survival, in neurons from WT or RhoB KO mice, as assessed by mitochondrial XTT reduction to formazan, following exposure to 10 µm A23187 for 2.5 h, or 500 nm STS for 24 h. Neurons lacking RhoB show increased survival after exposure to STS, *P < 0.05 vs. WT (t-test).