FIGURE 5.

CP681301 has dose- and time-dependent effects on BACE1, Cdk5, and caspase 3 cleavage in primary neurons. A, after 14 days in culture, murine primary embryonic neurons were treated with CP681301 at 0.5, 1.0, and 2.0 μm or DMSO vehicle (veh) for 24, 48, 72, or 96 h and then lysed in RIPA buffer. Immunoblot analysis of treated neuron lysates showed that BACE1 levels increased in a time- and dose-dependent fashion, whereas Cdk5 levels were significantly reduced. B, cleaved 17-kDa caspase 3 fragment in lysates of treated primary neuron cultures in A was analyzed by immunoblot. The ratio of cleaved to full-length caspase 3 was maximal at 72 h with all concentrations of CP681301, slightly anticipating the maximum BACE1 increase observed at 96 h (A). Error bars, mean ± S.E.; *, p ≤ 0.05; **, p ≤ 0.01; ***, p ≤ 0.001; NS, not significant.