Figure 4.
Reduced APP processing before stretch abrogates stretch-induced APP transport defects. A, Kymographs and quantitative analysis of the percentage of APP-YFP puncta moving anterogradely and retrogradely immediately after stretch in neurons exposed to βsi-IV (40 μm), CE (5 μm), or vehicle (DMSO 0.01%) during 1 h before being stretched. Quantitative analysis of APP axonal transport parameters in nonstretched neurons exposed to βsi-IV or CE compared with vehicle are displayed in Extended Data Figure 4-1. Data are shown as relative to the prestretch condition for each experimental group (dashed red line). *p = 0.0506, anterograde compared to pre-stretch condition. n = 4 or more. B, Percentage of APPMV-YFP puncta moving before and immediately after stretch, and respective kymographs (n = 6). C, Representative images of neurites transfected with APP-YFP, fixed immediately after stretch, labeled with antibodies against APP and Aβ42, and quantitative analysis of Aβ42-puncta number and puncta intensity compared with control (puncta number: *p = 0.041; puncta intensity: *p = 0.0436). Data are mean ± SEM (A,B) and median and quartiles (C). Data were compared by unpaired Student's t test. Scale bars: A, B, 10 µm. Scale C, 5 µm.