Figure 6. Blocking the intraluminal sorting of APP enhances its amyloidogenic processing.

a) Confocal analysis of HeLa cells transfected with Rab5_Q79L^myc and APP_WT^GFP (top panel) or APP_3R^GFP (middle panel). Cells were labeled with an anti-myc antibody (red) and counterstained with DAPI (blue). Scale bar = 10µm.

b) Bar diagram showing the quantification of the endosomal distribution of human APP^GFP expressed as % of total endosomal APP^GFP: internal = inside endosomal lumen, peripheral = limiting membrane of the endosomes. Values denote means ± SEM (for each construct, n = 18 cells from 3 experiments with an average quantification of 15 endosomes per cell). ***, denotes P values < 0.001 from a Student's t-test.

c) Confocal analysis of mouse hippocampal neurons transfected at DIV9 with Rab5Q79L^GFP and APP_WT^mCherry and fixed after a 24 h treatment with γ-secretase inhibitor XXI. Scale bar =10 µm. The inset shows APP-containing endosomes.

d) Bar diagram showing the quantification of the endosomal distribution of human APP_WT^mCherry and APP_3R^mCherry in hippocampal neurons processed as described in (c). The APP^mCherry distribution is expressed as % of total endosomal APP^mCherry: internal = inside endosomal lumen, peripheral = limiting membrane of the endosomes. Values denote means ± SEM (n=45 and 18 cells for APP_WT^mCherry and APP_3R^mCherry, respectively from 3 experiments with an average quantification of 20 endosomes per cell). **, denotes P values < 0.01 from a Student's t-test.