Fig. 7
From: Astrocytic uptake of neuronal corpses promotes cell-to-cell spreading of tau pathology
Astrocytes with deposits of synthetic or brain-derived tau secrete tau proteoforms with elevated seeding capacity. Evaluation of tau seeding efficacy using the RD tau P301S FRET biosensor (HEK293T cells). a Schematic outline of the experimental set-up. Astrocytes were exposed to 200 nM Tau-F or equivalent levels of human AD brain derived tau (BDTau-F) for 3 days, and incubated for 4 days in tau-free medium (3d + 4d). Tau biosensor cells were then exposed to either Tau-F directly, astrocyte medium from unexposed astrocytes (AM) or astrocyte conditioned medium (ACM). b Representative YFP-intensity images of biosensor cells exposed to medium from control astrocytes, Tau-F or ACMTau−F. c Quantification of YFP signal from images in b. d Quantification of tau in ACM of Tau-F exposed astrocytes by BT2 and T46 ELISA. e Representative images from biosensor cells exposed to control astrocyte medium, BDTau-F (direct exposure to brain derived tau diluted in astrocyte medium) or ACMBDTau−F (astrocytes conditioned medium from BDTau-F exposed astrocytes). f Quantification of YFP signal from images in e. YFP emission using a 405 nm laser to excite the cells was captured using an LSM700 confocal microscope. YFP IntDen was normalized to the area covered by cells/field of view. Scale bars = 50 µm. One-way ANOVA was used for stastical analysis in c, whilst Kruskal–Wallis test was used in d and f. *p < 0.05, **p < 0.01, ***p < 0.005, ****p < 0.0001