title: Targeting prion propagation using peptide constructs with signal sequence motifs.
abstract: Synthetic peptides with sequences derived from the cellular prion protein (PrP(C)) unprocessed N-terminus are able to counteract the propagation of proteinase K resistant prions (PrP(Res), indicating the presence of the prion isoform of the prion protein) in cell cultures (Löfgren 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 PrP(C) 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 mPrP1-28 sequence were analyzed for anti-prion effects, measured as disappearance of proteinase K resistant prions (PrP(Res)) 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 PrP(C) can be replaced with the signal peptide from the Neural cell adhesion molecule-1; NCAM11-19, with a retained capacity to reduce PrP(Res) levels. The anti-prion effect is lost if the polycationic N-terminal PrP(C)-motif is conjugated to any conventional CPP, such as TAT48-60, 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 PrP(C)-motif to a subcellular location where prion conversion occurs (most likely the Endosome Recycling Compartment), thereby targeting prion propagation.
authors.affiliation: The Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden. Electronic address: k.l.soderberg@live.com.
authors.forename: Kajsa Löfgren
authors.initials: KL
authors.lastname: Söderberg
authors.affiliation: The Department of Neurochemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Guterstam
authors.affiliation: The Department of Neurochemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Ulo
authors.initials: U
authors.lastname: Langel
authors.affiliation: The Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden. Electronic address: astrid@dbb.su.se.
authors.forename: Astrid
authors.initials: A
authors.lastname: Gräslund
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D019002:CD56 Antigen / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002461:Cell Line, Transformed; D051379:Mice; D018621:PrPC Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D021382:Protein Sorting Signals
chemical_list: D019002:CD56 Antigen; C501063:Ncam1 protein, mouse; D018621:PrPC Proteins; D021382:Protein Sorting Signals
keywords: Cell penetrating peptide; Polycationic motif; Prion; Signal peptide