Divalent cation tolerance protein binds to β-secretase and inhibits the processing of amyloid precursor protein

摘要

The deposition of amyloid-beta is a pathological hallmark of Alzheimer's disease. Amyloid-beta is derived from amyloid precursor protein through sequential proteolytic cleavages by β-secretase (beta-site amyloid precursor protein-cleaving enzyme 1) and γ-secretase. To further elucidate the roles of beta-site amyloid precursor protein-cleaving enzyme 1 in the development of Alzheimer's disease, a yeast two-hybrid system was used to screen a human embryonic brain cDNA library for proteins directly interacting with the intracellular domain of beta-site amyloid precursor protein-cleaving enzyme 1. A potential beta-site amyloid precursor protein-cleaving enzyme 1-interacting protein identified from the positive clones was divalent cation tolerance protein. Immunoprecipitation studies in the neuroblastoma cell line N2a showed that exogenous divalent cation tolerance protein interacts with endogenous beta-site amyloid precursor protein-cleaving enzyme 1. The overexpression of divalent cation tolerance protein did not affect beta-site amyloid precursor protein-cleaving enzyme 1 protein levels, but led to increased amyloid precursor protein levels in N2a/APP695 cells, with a concomitant reduction in the processing product amyloid precursor protein C-terminal fragment, indicating that divalent cation tolerance protein inhibits the processing of amyloid precursor protein. Our experimental findings suggest that divalent cation tolerance protein negatively regulates the function of beta-site amyloid precursor protein-cleaving enzyme 1. Thus, divalent cation tolerance protein could play a protective role in Alzheimer's disease. Research Highlights (1) Beta-site amyloid precursor protein-cleaving enzyme 1 is a critical enzyme in the processing of amyloid beta precursor protein and participates in the production of amyloid beta during the development of Alzheimer's disease. In this study, divalent cation tolerance protein was identified as a novel interaction partner for beta-site amyloid precursor protein-cleaving enzyme 1 using the yeast two-hybrid screening system. (2) Divalent cation tolerance protein associates with endogenous beta-site amyloid precursor protein-cleaving enzyme 1 in the neuroblastoma cell line N2a. The overexpression of divalent cation tolerance protein did not affect the protein levels of beta-site amyloid precursor protein-cleaving enzyme 1; however, it led to increased levels of amyloid beta precursor protein with a concomitant decrease in the amyloid precursor protein cleavage product, amyloid precursor protein C-terminal fragment. (3) Divalent cation tolerance protein negatively regulates the function of beta-site amyloid precursor protein-cleaving enzyme 1 and may play a protective role in the development of Alzheimer's disease.