Fig.7.

Aβ₄₂ is trafficked through endosomes (Rab11) to the lysosome compartment (LAMP-1) following internalization. SH-SY5Y treated from 3 to 72 h with FITC-Aβ₄₂ with or without AD serum. ICC was used to detect Rab-11 (early endosomes) and LAMP-1 (late endosomes/early lysosome marker). Co-localization was detected by superposition of red and green signals to yield yellow fluorescence. At 3 h, nearly all internalized FITC Aβ₄₂ was associated with early endosomes (Rab-11). In cells treated for 3 h and 72 h with FITC Aβ₄₂ in the presence of serum from an AD patient, co-localization of Aβ₄₂ and IgG was evident, although some internalization of Aβ₄₂ also occurred independently of IgG. At 72 h, little or no co-localization of Aβ₄₂ with Rab11 was detected, but significant accumulations of co-localized Aβ₄₂ and LAMP-1 (lysosomes) were common. Rab-11, early endosome; LAMP-1, lysosomal marker; AD, Alzheimer’s disease human serum; green arrow, Aβ₄₂; red arrow, secondary protein of interest; yellow arrow, co-localization; **p < 0.01; ***p < 0.001; Scale bar = 10 μm.