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P1‐482: Prion protein regulates the β‐secretase cleavage of the Alzheimer amyloid precursor protein through direct interaction with BACE1
Author(s) -
Griffiths Heledd H.,
Hooper Nigel M.
Publication year - 2008
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2008.05.1065
Subject(s) - amyloid precursor protein , hek 293 cells , immunoprecipitation , amyloid precursor protein secretase , peptide , chemistry , cleavage (geology) , biochemistry , microbiology and biotechnology , western blot , biology , alzheimer's disease , gene , medicine , paleontology , disease , fracture (geology) , pathology
Background: The cellular prion protein (PrP) regulates the proteolytic processing of the amyloid precursor protein (APP) by inhibiting the -secretase, BACE1, thereby precluding the formation of the amyloid (A ) peptide. Co-immunoprecipitation studies have demonstrated that PrP associates with BACE1, an interaction which is diminished by the presence of glycosaminoglycans (GAGs) such as heparin. Using various constructs of PrP, the inhibitory effect was found to be mediated by the 4 residue KKRP sequence at the N-terminus of PrP, a sequence also known to bind GAGs. To further establish the molecular mechanism of the interaction, the human homolog of BACE1, BACE2 was used as a tool to map the BACE1-PrP interaction site on the BACE1 structure. BACE2 shares 59% sequence similarity and 43% identity with BACE1. Methods: SH-SY5Y cells and HEK cells co-expressing PrP with either BACE1 or BACE2 were established. Isolated membrane preparations and conditioned media were subjected to western blot analysis and antibodies specific to BACE1, BACE2, PrP, sAPP , sAPP and actin were used. The activities of BACE1 and BACE2 were measured using a fluorescent peptide substrate based on the Swedish mutant APP sequence. Interaction studies between recombinant BACE1, BACE2 and PrP were carried out in an ELISA format. Results: Similar to BACE1, PrP inhibited the BACE2 cleavage of APP in SH-SY5Y and HEK cells. However, in contrast to BACE1, PrP reduced the activity of BACE2 towards a fluorogenic peptide substrate. BACE1 and BACE2 dimers were identified using native and reducing conditions, and the complexes were not perturbed by the presence of PrP. In the ELISA recombinant BACE1 bound to PrP. The effect of a range of GAGs, including heparin, on the interaction is being investigated. Conclusions: These data provide a better understanding of the nature of the interaction between PrP and BACE1, and the role that PrP plays in the pathogenesis of Alzheimer’s disease.