Figure 3: Pathogenic mutant Tau increases F-actin levels and reduces synaptic vesicle mobility at presynaptic terminals.
From: Tau association with synaptic vesicles causes presynaptic dysfunction
Drosophila larvae used in these assays express UAS-Tau (WT, R406W, V337M or P301L) under the D42-Gal4 motor neuron driver. (a,b) Immunolabeling of LifeAct-GFP probing for F-actin within synaptic boutons. Representative images of immunolabeling (a) and quantification of LifeAct-GFP intensity (b). One-way ANOVA, ***P<0.0001, n=12 (WT, R406W, V337M, P301L) or 14 (Control) NMJs (two NMJs per animal). Scale bar, 5 μm. (c–f) FRAP measurement of vesicle mobility within synaptic boutons. Representative images acquired immediately before photobleaching (pre-bleach) and immediately after bleaching at 0–60 s post-bleaching time points (c). Plot of fluorescence recovery (% of initial fluorescence) over time and fit with double-exponential curve (d). Plot of fast recovery rates calculated from fluorescence recovery curve (e) One-way ANOVA, **P=0.0011 (R406W), ***P=0.0001 (V337M), *P=0.0158 (P301L), n=24, 21, 22, 20, 25 (Control, WT, R406W, V337M, P301L) boutons (3–5 boutons per animal). Plot of slow recovery rates (f). One-way ANOVA, *P=0.0001 (R406W, V337M), *P=0.0250 (P301L), n=24, 21, 22, 20, 25 (Control, WT, R406W, V337M, P301L) boutons (3–5 boutons per animal). Scale bar, 5 μm. Data present mean±s.e.m. (g,h) Proposed model of Tau clustering synaptic vesicles to F-actin to restrict reserve pool vesicle mobilization and release.
