Effects of δ-Catenin on APP by Its Interaction with Presenilin-1.

Alzheimer's disease (AD) is the most frequent age-related human neurological disorder. The characteristics of AD include senile plaques, neurofibrillary tangles, and loss of synapses and neurons in the brain. β-Amyloid (Aβ) peptide is the predominant proteinaceous component of senile plaques. The amyloid hypothesis states that Aβ initiates the cascade of events that result in AD. Amyloid precursor protein (APP) processing plays an important role in Aβ production, which initiates synaptic and neuronal damage. δ-Catenin is known to be bound to presenilin-1 (PS-1), which is the main component of the γ-secretase complex that regulates APP cleavage. Because PS-1 interacts with both APP and δ-catenin, it is worth studying their interactive mechanism and/or effects on each other. Our immunoprecipitation data showed that there was no physical association between δ-catenin and APP. However, we observed that δ-catenin could reduce the binding between PS-1 and APP, thus decreasing the PS-1 mediated APP processing activity. Furthermore, δ-catenin reduced PS-1-mediated stabilization of APP. The results suggest that δ-catenin can influence the APP processing and its level by interacting with PS-1, which may eventually play a protective role in the degeneration of an Alzheimer's disease patient.