Figure 3.

Impaired Axonal Lysosome Transport and Proteolysis Deficits in Human APP and PSEN1 Mutant Neurons

(A) Representative kymographs showing transport of lysosomes labeled with LysoTracker Red DND 99. Scale bar, 10 μm.

(B) Significant increase in the average size of axonal lysosome in both APP and PSEN1 mutant (Y115C, M146I) neurons, compared with non-demented control (one-way ANOVA with Tukey correction between control and AD neurons in each case). Total number of axons measured (n): 35 (Control), 32 (APP V717I), 25 (APPdup), 45 (Ts21), 33 (PSEN1 Y115C), and 28 (PSEN1 M146I). Error bars, SEM.

(C) Significant reduction in lysosome motility in both anterograde and retrograde directions in both APP and PSEN1 mutant neurons, compared with controls (one-way ANOVA with Tukey correction between controls and AD neurons in each case). Total number of axons measured (n): 35 (Control 1), 32 (Control 2), 32 (APP V717I), 25 (APPdup), 45 (Ts21), 33 (PSEN1 Y115C), and 28 (PSEN1 M146I). Error bars, SEM.

(D) Proteolysis deficits in both APP and PSEN1 mutant (Y115C, M146I) neurons, as detected by live imaging of iPSC-derived cortical neurons co-labeled with 100 nM LysoTracker Red DND-99 and BODIPY-FL-pepstatinA. Scale bar, 10 μm.

(E) Significant reduction in the percentage of lysosomes that contained CatD-positive signals in both APP and PSEN1 mutant (Y115C, M146I) neurons, compared with non-demented controls (one-way ANOVA with Tukey correction between controls and AD neurons in each case). Axons were measured in three independent experiments, with total numbers of axons (n) indicated within each bar. Error bars, SEM.

See also Figures S3 and S4.