Identification of novel ?-secretase-associated proteins in detergent-resistant membranes from brain.

ABSTRACT: In Alzheimer disease, oligomeric amyloid ?-peptide (A?) species lead to synapse loss and neuronal death. ?-Secretase, the transmembrane protease complex that mediates the final catalytic step that liberates A? from its precursor protein (APP), has a multitude of substrates, and therapeutics aimed at reducing A? production should ideally be specific for APP cleavage. It has been shown that APP can be processed in lipid rafts, and ?-secretase-associated proteins can affect A? production. Here, we use a biotinylated inhibitor for affinity purification of ?-secretase and associated proteins and mass spectrometry for identification of the purified proteins, and we identify novel ?-secretase-associated proteins in detergent-resistant membranes from brain. Furthermore, we show by small interfering RNA-mediated knockdown of gene expression that a subset of the ?-secretase-associated proteins, in particular voltage-dependent anion channel 1 (VDAC1) and contactin-associated protein 1 (CNTNAP1), reduced A? production (A?40 and A?42) by around 70%, whereas knockdown of presenilin 1, one of the essential ?-secretase complex components, reduced A? production by 50%. Importantly, these proteins had a less pronounced effect on Notch processing. We conclude that VDAC1 and CNTNAP1 associate with ?-secretase in detergent-resistant membranes and affect APP processing and suggest that molecules that interfere with this interaction could be of therapeutic use for Alzheimer disease.

SUBMITTER: Hur JY 

PROVIDER: S-EPMC3320946 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature