Fig. 1

Tau PFF-induced integrin signaling is distinct from physiological integrin activation. (A) Immunoblotting (IB) shows the phosphorylation of FAK at Tyr 397 (pFAK) in primary astrocytes (PAs) treated as indicated for 2 h. Total FAK and astrocyte marker GFAP were used as loading controls. PF271, PF-562271; TPS887, brain extract from a 12-month-old tau-P301S transgenic mouse. The numbers indicate the relative level of pFAK ± SD (n = 3 biological repeats) as determined by densitometry. ****, p < 0.0001 by One-way ANOVA. (B) Schematic diagram of the cell toxicity assay (C) iPSC-differentiated iNeurons treated with the indicated condition medium (CM) from PAs treated with PBS, tau PFF or OPN (see methods) were stained with a green-fluorescent dye to label viable cells and a red-fluorescent dye to label dead cells. The graph shows the quantification of cell death as indicated by red fluorescent dots. Error bars indicate means ± SD. ****, p < 0.0001 by one-way ANOVA with Dunnett’s multiple comparison test. n = 3 biological repeats. AU, arbitrary unit. (D) Tau PFF and OPN induce similar gene expression changes. LFC, Log (2) Fold Change. (E) OPN (20 μg/ml) and tau PFF (200 nM) activate integrin signaling. qRT-PCR test of selected integrin target genes in tau PFF- and OPN-treated astrocytes (6 h). Error bars indicate means ± SD. n = 3 biological repeats. (F) Principal component analysis (PCA) of tau PFF- and OPN-induced gene expression changes. (G) Heat maps showing gene expression changes (LFC normalized by PBS-treated conditions) for the indicated pathways. The heat map represents the average of 3 biological repeats. (H) A functional interaction map of genes activated more by tau PFF than OPN. The color indicates the relative LFC by tau PFF compared to PBS-treated samples. The scale indicates fold change in log2 (LFC)