Figure 4

The neuronal type-1 IFN response to Aβ1-42 is IRF7 dependent and mimics an LPS-induced interferon signature. Human BE(2) M17 neuroblastoma cells, transfected with an IRF7 knockdown (KD) construct or negative control (NC) plasmid, were treated with 7.5 μM Aβ1-42 for 24 to 96 h. Q-PCR was performed to analyse (A) IFNα and (B) IFNβ mRNA levels post-treatment (*p < 0.05, n = 9 to 12, unmatched two-way ANOVA, Bonferroni post hoc test, alternative clone data can be viewed in Additional file 4: Figure S2). Cells were treated with 100 ng/ml LPS for 0.5 to 24 h and (C) IFNα and (D) IFNβ mRNA levels were analysed by Q-PCR (*p < 0.05, n = 7 to 9, unmatched two-way ANOVA, Bonferroni post hoc test). (E) The phosphorylation of STAT-3 in the Aβ1-42-treated cultures was analysed by Western blot analysis. (F) Corresponding densitometry. (**p < 0.01, n = 6, unmatched two-way ANOVA, Bonferroni post hoc test). (G) The protein lysates of the LPS-treated cells were also analysed for STAT-3 phosphorylation by Western blot with (H) corresponding densitometry (*p < 0.05, n = 12, unmatched two-way ANOVA, Bonferroni post hoc test). For densitometry calculations, phosphorylation intensity was measured in arbitrary units (A.U.) and normalised to the STAT-3:β-actin intensity ratio. All graphical data is displayed as mean ± SEM with treatment time on the x axis. Full-size uncropped Western blots of Aβ- and LPS-treated cultures can be viewed in Additional file 6: Figure S5 and Additional file 7: Figure S6, respectively.