Structural and mechanistic commonalities of amyloid-β and the prion protein

Amyloid beta (A beta) is a major causative agent of Alzheimer disease (AD). This neurotoxic peptide is generated as a result of the cleavage of the Amyloid-Precursor-Protein (APP) by the action of beta-secretase and g-secretase. The neurotoxicity was previously thought to be the result of aggregation. However, recent studies suggest that the interaction of A beta with numerous cell surface receptors such as N-methyl-D-aspartate (NMDA), receptor for advanced glycosylation end products (RAGE), P75 neurotrophin receptor (P75(NTR)) as well as cell surface proteins such as the cellular prion protein (PrPc) and heparan sulfate proteoglycans (HSPG) strongly enhances A beta induced apoptosis and thereby contributes to neurotoxicity. This review focuses on the molecular mechanism resulting in A beta-shedding as well as A beta-induced apoptotic processes, genetic risk factors for familial AD and interactions of A beta with cell surface receptors and proteins, with particular emphasis on the cellular prion protein. Furthermore, comparisons are drawn between AD and prion disorders and the role of laminin, an extracellular matrix protein, glycosaminoglycans and the 37 kDa/67 kDa laminin receptor (LRP/LR) have been highlighted with regards to both neurodegenerative diseases.