Figure 3.

Degradation of internalized Tau in microglia via endosome–lysosome Rab5 pathway. A microglia cell was exposed to hTau40 monomer and aggregates in the presence and absence of ALA and observed for the levels of Rab5 (green) and Tau (red) by fluorescence microscopy. The degradation of internalized Tau was studied with the early endosomal marker and late endosomal markers. (a) In the pathway, the maturation of phagocytic vesicle takes place that can be marked with the early endosomal marker Rab5 and late endosomal marker Rab7. We observed the colocalization of internalized Tau with endosomal markers (Rab5) to trace the degradation of internalized Tau. (b) The fluorescence microscopy images indicate the levels of endosomal markers and their colocalization with internalized Tau. The enlarged panel indicates specific area in the cells showing colocalization between Rab5 and Tau; scale bar is 20 μm. (c) The quantification of mean intensity of endosomal markers was carried out with ZEN 2.3 software; significance is P < 0.05. (d) Expression analysis of early endosomal marker (Rab5) was observed by western blot after various treatments of hTau40 monomer, aggregates, and ALA after 24 h. (e) Quantification of protein bands is plotted as intensity and normalized with β-actin as a loading control