FIGURE 1.

Amyloid plaque formation extracellular and tau pathology intracellular. Amyloid precursor protein (APP) is a transmembrane protein that can be cleaved by three kinds of secretases. In the process of amyloid plaque formation, APP is cleaved by β-secretase and γ-secretase sequentially, then amyloid-β peptides release to extracellular and clump together to form deposits (Aβ plaques). Tau plays a critical role in microtubule assembly and stabilization, hyperphosphorylation of tau leads to microtubules depolymerization, and paired helical filaments (PHF) aggregate to form tau neurofibrillary tangles (NFTs).