Figure 4.
Bim and cdk4 are required for neuron death evoked by Aβ. a, Bim knock-down prevents neuronal degeneration and death after Aβ treatment. Cortical neurons were transfected with pSIREN-Luc-shRNA-GFP (shLuc), pSIREN-Bim-shRNA-ZsGreen (shBim), or pSIREN-cdk4-shRNA-ZsGreen (shcdk4), maintained for 48 h, and then treated with 10 μm Aβ as indicated. Representative images of transfected neurons were taken in each case after 24 h of treatment. b, Bim shRNA and cdk4 shRNA provide protection against death evoked by Aβ. Cortical neurons were transfected with pSIREN-Luc-shRNA-GFP (shLuc), pSIREN-Bim-shRNA-ZsGreen (shBim), or pSIREN-cdk4-shRNA-ZsGreen (shcdk4), maintained for 48 h, and then treated with 10 μm Aβ as indicated. Numbers of surviving transfected (green) cells were counted just before treatment and after 24 and 48 h with or without treatment. Data represent means ± SEM of three experiments performed in triplicate. The asterisks denote statistically significant differences from control (shLuc): *p < 0.001. c, The induction of the Bim protein by Aβ is completely blocked by cdk inhibitors and incompletely blocked by a JNK inhibitor. Cortical neurons were treated with Aβ for 24 h in presence or absence of 1 μm flavopiridol (Flavo), 20 μm roscovitine (Rosco), or 10 μm JNK inhibitor (JNKI) (SP600125), and cell proteins were subjected to Western immunoblotting as in Figure 1c.