Targeting prion propagation using peptide constructs with signal sequence motifs.

Area of Science:

• Neuroscience
• Biochemistry
• Molecular Biology

Background:

• Synthetic peptides derived from the cellular prion protein (PrP(C)) N-terminus can inhibit prion propagation.
• These anti-prion peptides possess cell-penetrating peptide (CPP) characteristics, featuring a prion protein hydrophobic signal sequence and a polycationic motif (KKRPKP).

Purpose of the Study:

• To identify the essential sequence elements within KKRPKP-conjugates responsible for their anti-prion activity.
• To investigate the role of the signal peptide and the polycationic motif in targeting prion propagation.

Main Methods:

• Analysis of truncated and modified peptide constructs derived from mouse PrP(C) residues 1-28.
• Testing peptide efficacy in prion-infected neuronal GT1-1 cells using prion strains RML and 22L.
• Quantification of anti-prion effects by measuring the reduction of proteinase K resistant prions (PrP(Res)).

Main Results:

• A 5-amino acid N-terminal shortening of the signal peptide abolished the anti-prion effect.
• The PrP(C) signal peptide could be substituted with the signal peptide from Neural cell adhesion molecule-1 (NCAM11-19) while retaining anti-prion activity.
• Conjugating the polycationic PrP(C)-motif to conventional CPPs (TAT48-60, transportan-10, penetratin) eliminated the anti-prion effect.

Conclusions:

• The signal peptide sequence is critical for the anti-prion activity of KKRPKP-conjugates.
• A non-prion signal peptide can mediate anti-prion effects, suggesting a generalizable mechanism.
• The proposed mechanism involves signal peptide-mediated transport of the prion-binding motif to the Endosome Recycling Compartment to inhibit prion conversion.