Figure 1.

Mechanism of AD pathogenesis. The amyloid pathway is important to accumulate neurotoxic Aβ plaque via releases of β-secretase, which produces extracellular sAPPβ and C99. Cleavage of the C99 fragment by γ-secretase releases Aβ oligomer, which subsequently produces Aβ peptide. By the action of α-secretase, two fragments of sAPPα and C83 are produced by the non-amyloid pathway. The non-amyloid pathway cleavages APP via α-secretase to produce two fragments: C83, an 83 amino acid intracellular C-terminal fragment, and extracellular sAPPα, soluble amyloid precursor protein α. Cleavage of the C83 fragment by γ-secretase yields a P3 peptide and CTFγ.