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. 2005 Feb 2;25(5):1149–1158. doi: 10.1523/JNEUROSCI.4736-04.2005

Figure 6.

Figure 6.

Aβ-induced Bcl-w downregulation and Smac release are dependent on JNK activation. A, JNK is activated (phosphorylated) in a time-dependent manner by Aβ. Neuron cultures were treated with 25 μm Aβ25-35 for the indicated times and then probed by Western blot with phospho-JNK (p-JNK) or pan JNK antibodies. The JNK inhibitor SP600125 (100 nm) decreases both basal levels (B) and Aβ-induced increases (C) in phosphorylated JNK, as determined by Western blot with p-JNK and pan JNK antibodies. D, Inhibition of JNK with SP600125 inhibits Aβ-induced Bcl-w downregulation. Neuron cultures were pretreated with 100 nm SP600125 for 90 min, followed by exposure to 25 μm Aβ25-35 for the indicated times, and were then analyzed for Bcl-w mRNA expression by RT-PCR. β-Actin served as internal control. E, Western Blot confirmed that SP600125 inhibits Aβ-induced Bcl-w downregulation (top). Neuron cultures were pretreated with 100 nm SP600125 for 90 min, followed by exposure to 25 μm Aβ25-35 for 48 h, and were then analyzed for Bcl-w expression by Western blot. As a control, Aβ-induced Bcl-xL downregulation was also inhibited by SP600125 (middle). β-Tubulin was used as a control (bottom). F, Relative amounts of Bcl-w were determined by densitometric scanning of Western blots from three independent experiments and are represented as a mean ± SEM percentage of control values. **p < 0.01 relative to the Aβ condition. G, JNK inhibition attenuates Aβ-induced Smac release. Neuron cultures were pretreated with 100 nm of SP600125 for 90 min, followed by exposure to 25 μm Aβ25-35 for 48 h, and were then analyzed for Smac content in mitochondrial (Mt) or cytosolic (Cyt) extracts Western blot. H, JNK inhibition blocks Aβ-induced neuronal death. Neuron cultures were pretreated with increasing concentrations (0-1 μm) of SP600125 for 90 min, followed by exposure to 25 μm Aβ25-35 for 48 h, and were then assayed for cell viability. Data show mean ± SEM cell viability from a representative experiment (n = 6). Significance is defined as **p < 0.01 in comparison to Aβ25-35 condition. Ctrl, Control.