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Title: Fine mapping of the Aβ oligomer binding site on PrP
Author: Wright, D. M. P.
ISNI:       0000 0004 7964 7797
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2016
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Soluble amyloid-beta (Aβ) oligomers play a prominent role in the pathogenesis of Alzheimer's disease. Several lines of evidence suggest that the neurotoxicity elicited by Aβ oligomers may be mediated by one or more receptors, including the cellular form of the prion protein (PrPC). PrP has been shown to bind Aβ oligomers via its 95-110 region, resulting in various deleterious effects. However, fine mapping of the Aβ oligomer binding site on PrP is yet to be performed. An alanine mutagenesis screen of the 95-110 region was therefore carried out here to identify residues critically involved in the PrP-Aβ interaction. Recombinant forms of human and murine PrP displayed low nanomolar affinity for amyloid-derived diffusible ligand (ADDL) preparations consisting predominantly of protofibrillar Aβ, which exhibited both PrP-dependent and PrP-independent toxicity. The affinity of the interaction was not affected by deletion of residues 23-27, as previously suggested. Full-length, alanine-mutant forms of recombinant mouse PrP displayed similar affinity for ADDLs to the non-mutated protein, with the exception of a QW97-98AA mutant, which displayed weaker binding when surface-immobilised. Surprisingly, the QW97-98AA mutant displayed no loss of affinity for ADDLs when tested in a solution-based competition assay. These findings were confirmed when alanine mutants were expressed in a heterologous COS7 cell model of PrP-dependent Aβ binding. In this COS7 cell model, two novel, small molecule inhibitors of cellular PrP-Aβ binding - Chicago Sky Blue 6B and 6-OH-L-DOPA - were also identified. Taken together, the results of this study demonstrate that PrP displays high affinity for ADDLs, and that residues 97-98 modulate the avidity, rather than the affinity of the PrP-Aβ interaction. This has implications for the development of potential therapeutics, which, based on the results of this study, should target the majority of the 95-110 region, rather than smaller sub-sites therein.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available