Fig. 4.

APMAP interacting proteins are endogenous modulators of APP processing and Aβ production. a The knockdown of the indicated APMAP-interacting proteins was mediated by siRNA in HEK cells overexpressing APP bearing the Swedish mutation that causes early-onset familial Alzheimer’s disease (HEK-APPSwe). After 3 days of treatment, whole cell extracts from biological triplicates were prepared and analyzed by Western blot for the siRNA protein targets, APP-FL, APP-CTFs and APMAP. Actin served as a protein loading control. Scramble: allstar control siRNA; APP-FL: APP full-length; APP-CTFs: APP-C-terminal fragments. siRNA duplexes are listed in the Materials and Methods section. b The conditioned media of the siRNA-treated cells in (a) were used to quantitatively measure, by ELISA, the secreted peptides Aβ1-40 and Aβ1-42. Note the correlation between APP-CTFs levels estimated by densitometric analysis of the APP-CTFs Western blot bands in (a) and the production of both Aβ1-40 and Aβ1-42. Student’s t-test was applied for statistical analysis; the significance is shown as the mean ± SEM, *P < 0.05; **P < 0.01; ***P < 0.001; Aβ40 and Aβ42: n = 6/group; APP-CTFs: n=3/group