C-terminal peptides modelling constitutive PrPC processing demonstrate ameliorated toxicity predisposition consequent to {alpha}-cleavage

Misfolding of cellular prion protein (PrPC) to β-strand rich conformations (PrPres) constitutes a key event in prion disease pathogenesis. PrPC can undergo either of two constitutive endoproteolytic events known as α- and β-cleavage, yielding C-terminal fragments known as C1 and C2, respectively. It is unclear whether C-terminal fragments generated through α- and β-cleavage, especially C2, directly influence pathogenesis. Consequently, we compared the biophysical properties and neurotoxicity of recombinant human PrP fragments recapitulating α- and β-cleavage, namely huPrP112-231 (equating to C1) and huPrP90-231 (equating to C2). Under conditions we employed, huPrP112-231 could not be induced to fold into a β-stranded isoform and neurotoxicity was not a feature for monomeric or multimeric assemblies. In contrast, huPrP90-231 easily adopted a β-strand conformation, demonstrated considerable thermostability and was toxic to neurons. Synthetic PrP peptides modelled on α- and β-cleavage of the unique Y145STOP mutant prion protein corroborated the differential toxicity observed for recombinant huPrP112-231 and huPrP90-231 and suggested that the persistence of soluble, oligomeric, β-strand rich PrP conformers was required for neurotoxicity. Our results additionally support that α- and β-cleavage of PrPC generate biophysically and biologically non-equivalent C-terminal fragments and that...

Source: BJ Cell - January 20, 2014 Category: Biochemistry Authors: V A. Johanssen, T Johanssen, C L. Masters, A F. Hill, K J. Barnham, S J. Collins Tags: BJ Disease Source Type: research