The engineered peptide construct NCAM1-Aβ inhibits fibrillization of the human prion protein (PrP)

Abstract

In prion diseases, the prion protein (PrP) becomes misfolded and forms fibrillar aggregates that are responsible for prion infectivity and pathology. So far, no drug or treatment procedures have been approved for prion disease treatment. We have previously shown that engineered cell-penetrating peptide constructs can reduce the amount of prion aggregates in infected cells. However, the molecular mechanism underlying this effect is unknown. Here, we use atomic force microscopy (AFM) imaging to show that the amyloid aggregation and fibrillization of the human PrP protein can be inhibited by equimolar amounts of the 25 residues long engineered peptide construct NCAM1-Aβ.

Cell-Penetrating Peptides with Unexpected Anti-Amyloid Properties

“…All this seems to point towards a rapid co-aggregation process where large co-aggregates are formed which precipitate out of solution. Similar non-fibrillar co-aggregates were also observed for the PrP protein together with the NCAM-Aβ construct [27].…”

“…The effect was retained, and even enhanced, upon exchanging the PrP signal peptide into the NCAM1 signal peptide [26]. A study based on AFM imaging showed that co-aggregation between our constructs and the prion protein into non-fibrillar/non-amyloid aggregates appears to be an important molecular interaction underlying these results [27]. The NCAM1 signal peptide is shorter and less hydrophobic than its PrP counterpart, which leads to higher solubility and a lower aggregation propensity.…”

“…No exact molecular mechanism for the anti-prion effect of the CPP constructs has been pinpointed, although co-aggregation between the constructs and the amyloidogenic proteins and peptides appears to be one important aspect [8,20,27]. We hypothesize based on the above-mentioned experimental findings that the signal peptide sequence causes translocation of the peptides into cells where it co-localizes with and binds specifically to PrP Sc , through the KKRPKP recognition sequence.…”

“…The mPrP signal peptide segment was later exchanged into the slightly less hydrophobic signal peptide for a type-I membrane protein found in neuronal cells, i.e., the mouse neural cell adhesion molecule 1 (NCAM1) protein (mNCAM1 [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] ). This yielded the chimeric CPP construct mNCAM1 1-19 -mPrP [23][24][25][26][27][28] , which we refer to as NCAM-PrP. The peptides' variants and their properties are summarized in Figure 1A.…”

13C-isotope-editing of nanoscale infrared images reveals the action of an inhibi­tory peptide against amyloid-β aggregation

“…The aggregation of Aβ and of the human prion protein can be inhibited by certain cell-penetrating peptides (CPPs) in vitro, [37][38][39][40] which target secondary nucleation 39 and counteract the lethal damage inflicted by the Aβ peptide on neuroblastoma cells. 38 These particular CPPs contain a signal sequence for secretion and a short sequence from an amyloidogenic polypeptide: either from the prion protein or from Aβ.…”