Fig. 6.

Aβ upregulates Fas ligand expression in cortical neurons. A, Aβ induction of Fas ligand (FasL) mRNA. Cortical neurons were treated with 25 μm Aβ25–35, and total RNA was extracted at the indicated times. Expression of Fas ligand and S100 mRNAs was examined by semiquantitative RT-PCR. B, Induction of Fas ligand protein level by Aβ and kainic acid. Cortical neurons were treated with 25 μm Aβ25–35 or 200 μm kainic acid, and total cell extracts were prepared at the indicated times. The level of Fas ligand was determined by immunoblotting using anti-Fas ligand antibodies and quantified using the Wilcoxon test (*p < 0.05). C, Immunostaining using anti-Fas ligand (FasL) antibody. Neurons were treated with Aβ25–35 or kainic acid (KA) for 16 hr and fixed. The cells were incubated with anti-Fas ligand antibody, followed by anti-mouse biotin-conjugated secondary antibody and then Cy3-labeled streptoavidin and Hoechst 33258. D, Cortical neurons derived from wild-type and JNK3^−/− mice were treated with 25 μm Aβ25–35, and total RNA was extracted at 24 hr. Expression of Fas ligand and actin mRNAs was examined by semiquantitative RT-PCR. WT, Wild type;KO, knock-out.