Figure 2.

Aβ biogenesis. Normally, Aβ is derived from the transmembrane region of amyloid precursor protein (APP) through the sequential cleavage by BACE and γ-secretase. Under physiological conditions, Aβ maintains a steady-state level and is necessary for multiple physiological functions [168]. In AD, Aβ production is increased due to mutations in APP and/or in presenilin (PS1 and PS2) genes. There is an α-secretase cleavage site located between β- and γ-secretase cleavage sites that generates soluble, nonpathogenic peptides [8].