Fig 2: TSPO polymerization in C6, GL26, and B16 cells. (A) C6 cells showed two bands corresponding to 36 and 72 kDa TSPO polymers, whereas (B) GL26 and B16 cells displayed the monomeric 18 kDa TSPO form.

Fig 3: Amyloid- and Tau-induced cell death are not associated with TSPO changes. (A) C6 cells were treated with increasing concentrations of amyloid (0.015–20 µM) for 24 h. Cell survival was measured using the MTT assay and expressed as % from control. ***p < 0.001, as compared to untreated cells (two-way analysis of variance (ANOVA) with Dunnett’s multiple comparisons post hoc test). Example of western blot examination of the amyloid solution demonstrating the aggregated form of Aß42. (B) C6 cells were treated with increasing concentrations of Tau (0.015–0.25 µM) for 24 h. Cell survival was measured using the MTT assay and expressed as % from control. *p < 0.05; **p < 0.01; ***p < 0.001, as compared to untreated cells (two-way ANOVA with Dunnett’s multiple comparisons post hoc test). Example of western blot examination of the Tau solution demonstrating the monomeric form of Tau. (C) Examples of DAPI staining in control and Aß-treated cells demonstrate an apoptosis-like morphology. Scale bar: 20 µm. (D) Example of activated caspase-3/7 staining in control and Tau- and Aß-treated cells to demonstrate the increase in caspase-3/7 showing an apoptosis-mediated cell death. Scale bars: 20 µm. (E) Examples of 36 and 72 kDa TSPO polymers in C6 cells treated with 1 µM Aß for 24 h. The 36–72 kDa TSPO polymer ratio (F) and the TSPO density relative to total proteins (G) were quantified in control, 1 µM Aß-treated cells, and 0.05 µM Tau-treated cells and expressed relative to the control group.

Fig 4: Time course of FEPPA- and PBR28-induced cell death. (A) C6 cells were treated with 80 µM FEPPA or PBR28 for 1–4 days. Cell survival was measured using the MTT assay and expressed as % from control. *p < 0.05; **p < 0.01; ***p < 0.001, as compared to untreated cells and ##p < 0.01 as compared to the previous day (two-way ANOVA with LSD post hoc test). (B) Examples of DAPI staining (×400) at day 4 in control (left cell); FEPPA-treated cells demonstrate an apoptosis-like morphology (three right panels) Scale bar: 20 µm. (C) Example of activated caspase-3/7 staining in control and FEPPA-treated cells (50 µM) to demonstrate the increase in caspase-3/7 showing an apoptosis-mediated cell death. Scale bars: 20 µm. (D, E) C6 cells were treated with increasing concentrations of FEPPA or PBR28 (0.01–110 µM) for 4 days. Survival of FEPPA- (D) and PBR28-treated cells (E) was measured using the MTT assay and expressed as % from control. *p < 0.05; **p < 0.01; ***p < 0.001 (one-way ANOVA with the Dunnett’s multiple comparisons post hoc test). (F) Examples of 36 and 72 kDa TSPO polymers (upper panel) and total proteins (DB71 staining, lower panel) in C6 cells treated with 0 or 50 µM FEPPA for 4 days. (G) Corresponding 36 to 72 kDa TSPO polymer ratio and (H) TSPO density relative to total proteins. *p < 0.05 (one-way ANOVA with the LSD post hoc test).