Targeting prion propagation using peptide constructs with signal sequence motifs

• Synthetic peptides with sequences derived from the cellular prion protein (PrPc) unprocessed N-terminus are able to counteract the propagation of proteinase K resistant prions (PrPRes, indicating the presence of the prion isoform of the prion protein) in cell cultures (Lofgren et al., 2008). The anti-prion peptides have characteristics like cell penetrating peptides (CPPs) and consist of the prion protein hydrophobic signal sequence followed by a polycationic motif (residues KKRPKP), in mouse PrPc corresponding to residues 1-28. Here we analyze the sequence elements required for the anti-prion effect of KKRPKP-conjugates. Neuronal GT1-1 cells were infected with either prion strain RML or 22L Variable peptide constructs originating from the mPrP(1-28) sequence were analyzed for anti-prion effects, measured as disappearance of proteinase K resistant prions (PrPRes) in the infected cell cultures. We find that even a 5 amino acid N-terminal shortening of the signal peptide abolishes the anti-prion effect. We show that the signal peptide from PrPc can be replaced with the signal peptide from the Neural cell adhesion molecule-1; NCAMl(1-19), with a retained capacity to reduce PrPRes levels. The anti-prion effect is lost if the polycationic N-terminal PrPc-motif is conjugated to any conventional CPP, such as TAT(48-60), transportan-10 or penetratin. We propose a mechanism by which a signal peptide from a secretory or cell surface protein acts to promote the transport of a prion-binding polycationic PrPc-motif to a subcellular location where prion conversion occurs (most likely the Endosome Recycling Compartment), thereby targeting prion propagation.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

Prion

Signal peptide

Polycationic motif

Cell penetrating peptide

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