Figure 4.

Artificial lysosomal acidification causes degradation of Cy3-fAβ by microglia. (A) Lysosomal pH measurements. Microglia were incubated with fluorescein-rhodamine dextran for 16 h followed by a 4-h chase. The cells were pulsed with 25 mM NH₄Cl for 30 min, followed by rinsing and incubation in medium without NH₄Cl for 15, 45, or 60 min. At each time, lysosomal pH measurements were obtained from at least 750 lysosomes from four different fields, and the pH values from four different experiments done on four different days are shown. Error bars represent the SEM. (B) Degradation of Cy3-fAβ. Microglia were incubated for 60 min with 5 μg/ml Cy3-fAβ and chased for 72 h. During the chase period, lysosomes were acidified by ammonium pulse-wash Cy3 fluorescence power after 72 h normalized to the fluorescence power before the chase. The data represent the average of the normalized intensity values from four different experiments done on four different days. Error bars represent the SEM.