Neurotoxicity Of The Putative Transmembrane Domain Of The Prion Protein

It has been shown recently that the generation of an abnormal transmembrane form
of the prion protein ((Ctm)PrP) is involved in the neurodegeneration process
during inherited and infectious prion diseases but a causative relationship has
never been established. We wanted to know if and how the proposed transmembrane
domain of PrP could induce neuronal dysfunction. Thus, we investigated the
neurotoxic properties of two peptides whose sequences are encompassed within this
domain. We show that PrP peptides 118-135 and 105-132 as well as an amidated more
soluble peptide 105-132 induce the death of pure cortical neurons originating
from normal and PrP knockout mice. This can be correlated with the high
propensity of these peptides to insert stably into and to destabilize cell
membranes. Through this study, we have identified a novel mechanism of
neurotoxicity for PrP, which directly involves membrane perturbation; this
mechanism is independent of fibril formation and probably corresponds to the
effect of the transmembrane insertion of (Ctm)PrP.