Figure 5.

Aβ induces the expression of cell cycle regulatory proteins. (A) SK-N-MC cells were exposed to Aβ (5 μM) for 24 h. The mRNA expression levels of CDK5, P35 and P39 were analyzed by real-time PCR. The mRNA expression level was normalized by β-actin mRNA expression level. Data represent the mean ± SE. n = 4. (B) hif1α specific- and non-targeting (NT) siRNA were transfected to the cells for 24 h prior to Aβ treatment. Cyclin D₁, CDK4, cyclin E, CDK2, HIF1α and β-actin was detected by western blot. n = 3. (C–F) Cells were pretreated with trehalose (10 μM), rapamycin (10 nM), PF4708671 (10 μM) and cycloheximide (4 μM) for 30 min prior to Aβ treatment for 24 h. Cyclin D₁, CDK4, cyclin E, CDK2 and β-actin were detected by western blot. n = 3–6. (G) Mouse hippocampal neurons were transfected with hif1α specific- and NT siRNAs for 24 h prior to Aβ treatment for 24 h. Samples were blotted with Cyclin D₁, CDK4, cyclin E, CDK2 and β-actin specific antibodies. n = 3–6. (H) Mouse hippocampal neurons were pretreated with trehalose (10 μM) for 30 min and incubated with Aβ for 24 h. cyclin D₁, CDK4, cyclin E, CDK2, HIF1α and β-actin were analyzed by western blot. n = 3–6. Data are presented as a mean ± SE. *p < 0.05 vs. control, ^#p < 0.05 vs. Aβ treatment.