Fig. 6: PSEN2 expression in LE/Lys is required to maintain pre- and postsynaptic homeostasis.

a Representative images of DIV14 hippocampal neurons immunostained for PSEN2, LAMP1, PSD95 and Phalloidin. Zoomed insets show PSEN2 within LAMP1⁺ compartments close to PSD95 spots (highlighted by white arrow heads). b Representative images of PSEN2 in close proximity to post synaptic (PSD95) and presynaptic (Synaptobrevin2) compartments, further highlighted in zoomed insets (white arrow heads). c Quantification of %overlap of PSD95 with PSEN2 and LAMP1⁺ puncta in APPKI and APPxFADPSEN2 neurons from images in (a). d, e Quantification of PSD95 puncta per µm (d) and size (e) from images in (a, b). f Representative images of DIV14 hippocampal neurons immunostained for PSEN2, LAMP1 and AnkyrinG, a marker of the axonal initial segment. Zoomed insets highlight PSEN2 ⁺ /LAMP1⁺ vesicles in axons. Representative images were selected from two different coverslips stained from one culture. g Representative western blot of neuronal lysates probed for vGLUT1 and GLUA1 and quantified in (h) (vGLUT1) and (i) (GLUA1). j Representative images of DIV 14 hippocampal neurons immunostained for surface vGLUT1 and GLUA1, and with Phalloidin to label F-actin; quantified in (k) (vGLUT1) and (i) (GLUA1). All statistics were done by one-way ANOVA with Tukey’s correction for multiple testing compared to APPKI. All graphs are mean ± SEM and indicate scale bars and p-values. Triangles and circles represent the average per neuronal culture and individual cells, respectively.