NR AXNO
AU Griffiths,H.H.; Parkin,E.T.; Watt,N.T.; Turner,A.J.; Hooper,N.M.
TI Prion Protein Regulates the ß-Secretase Cleavage of the Alzheimer's Amyloid Precursor Protein through Interaction with Glycosaminoglycans
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Pathology and Pathogenesis P03.140
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Poster
AB
Background: Proteolytic processing of the amyloid precursor protein (APP) by ßsecretase, BACE1, is the initial step in the production of the amyloid ß (Aß) peptide which is involved in the pathogenesis of Alzheimer's disease. We have shown that the cellular prion protein (PrP) inhibits the cleavage of APP by BACE1 in cell and animal models.
Aim: To investigate the mechanism by which PrP inhibits the action of BACE1.
Results: Neither PrPdeltaGPI, which is not membrane attached, nor PrP-CTM, which is anchored by a transmembrane domain and is excluded from cholesterol-rich lipid rafts, reduced cleavage of APP, suggesting that to inhibit the BACE1 cleavage of APP PrP has to be localised to lipid rafts. Coimmunoprecipitation experiments demonstrated that PrP physically interacts with BACE1. However, PrP did not alter the activity of BACE1 towards a fluorogenic peptide substrate nor perturb the dimerisation of BACE1. Using constructs of PrP lacking either the octapeptide repeats or the 4 residues KKRP at the N-terminus of the mature protein (PrPdeltaN), we demonstrate that the KKRP sequence but not the octapeptide repeats, is essential for regulating the BACE1 cleavage of APP. As the KKRP sequence is known to participate in glycosaminoglycan (GAG) binding, we confirmed that PrPdeltaN did not bind to immobilised heparin. Addition of heparin to SH-SY5Y cells increased the amount of APP cleaved by BACE1 in a concentration-dependent manner and reduced the amount of BACE1 coimmunoprecipitated with PrP, suggesting that GAGs are required for PrP to interact with BACE1 and inhibit APP processing. Of a range of GAGs, including dextran sulphate, hyaluronic acid and chondroitin sulphate, investigated there was complete correlation between those that could restore BACE1 cleavage of APP in PrP expressing cells and those that bound PrP.
Conclusion: These data suggest a possible mechanism by which PrP regulates the ßcleavage of APP is through the N-terminus of PrP interacting via GAGs with one or more of the heparin binding sites on BACE1 within a subset of cholesterol-rich lipid rafts, thereby restricting access of BACE1 to APP.
Funded by the Medical Research Council of Great Britain.
AD H.H. Griffiths, E.T. Parkin, N.T. Watt, A.J. Turner, N.M. Hooper, University of Leeds, Institute of Molecular and Cellular Biology, UK
SP englisch
PO Schottland