Extended Data Fig. 7. Unmasking the amyloid core is essential for seeding in neurons.
a) Mouse primary cortical neurons treated with PBS, Alexa 488-labeled FL TDP-43 filaments, Alexa 488-labeled CP fibrils, and Alexa 488-labeled PK-unmasked TDP-43 filaments for 3 days and analyzed by ICC using an anti-full-length TDP-43 antibody. From left to right: DAPI staining showing the nucleus (blue), staining using anti- TDP-43 antibody (red), the fluorescence signal from Alexa 488 labeled fibrils (green), and staining with anti-MAP2 antibody identifying neurons (red), and orthogonal projections. b) Quantification of Alexa-488 labeled TDP-43 filaments/fibrils uptake in mouse primary cortical neurons. Bar plots show mean and whiskers s.e.m., with individual points representing a different experimental replica (n = 3). A one-way ANOVA followed by Tukey’s multiple comparisons test was used for the analysis; ∗P < 0.05. ns: non-significant. The statistics results and the exact p-value are provided in the source data. c) Mouse primary neurons after 3 days of treatment with Alexa 488-labeled FL TDP-43 filaments and PK-unmasked TDP-43 filaments and analyzed by ICC using an anti-phospho TDP-43 antibody (409/410). From left to right: DAPI staining showing the nucleus (blue), the fluorescence signal from Alexa 488 labeled fibrils (green), staining using anti-phospho TDP-43 antibody (red), and staining with anti-MAP2 antibody identifying neurons (red), and orthogonal projections.