Abstract
Prion diseases are associated with the conformational conversion of the cellular prion protein (PrPC) into the pathological scrapie isoform (PrPSc) in the brain. Both the in vivo and in vitro conversion of PrPC into PrPSc is significantly inhibited by differences in amino acid sequence between the two molecules. Using protein misfolding cyclic amplification (PMCA), we now report that the recombinant full-length human PrP (rHuPrP23-231) (that is unglycosylated and lacks the glycophosphatidylinositol anchor) is a strong inhibitor of human prion propagation. Furthermore, rHuPrP23-231 also inhibits mouse prion propagation in a scrapie-infected mouse cell line. Notably, it binds to PrPSc, but not PrPC, suggesting that the inhibitory effect of recombinant PrP results from blocking the interaction of brain PrPC with PrPSc. Our findings suggest a new avenue for treating prion diseases, in which a patient's own unglycosylated and anchorless PrP is used to inhibit PrPSc propagation without inducing immune response side effects.
Highlights
Prion diseases are associated with the conformational conversion of the cellular prion protein (PrPC) into the pathological scrapie isoform (PrPSc) in the brain
Using the protein misfolding cyclic amplification (PMCA) assay with wild-type and mutant PrP expressed in Chinese hamster ovary cells as substrates, Geoghegan et al further demonstrated that trans-dominant inhibition of prion propagation in vitro was not mediated by an accessory cofactor and proposed that PrP molecules compete for binding to a nascent seeding site on newly formed PrPSc molecules[15]
To investigate the effect of unglycosylated and anchorless PrP on human PrPSc formation, we performed the PMCA assay in which human PrPSc from brain homogenates of an iatrogenic Creutzfeldt-Jakob disease (CJD) was used as the seed while human PrPC from brain homogenates of transgenic mice expressing wild-type human PrP129V was used as the substrate
Summary
Prion diseases are associated with the conformational conversion of the cellular prion protein (PrPC) into the pathological scrapie isoform (PrPSc) in the brain Both the in vivo and in vitro conversion of PrPC into PrPSc is significantly inhibited by differences in amino acid sequence between the two molecules. Using the protein misfolding cyclic amplification (PMCA) assay with wild-type and mutant PrP expressed in Chinese hamster ovary cells as substrates, Geoghegan et al further demonstrated that trans-dominant inhibition of prion propagation in vitro was not mediated by an accessory cofactor and proposed that PrP molecules compete for binding to a nascent seeding site on newly formed PrPSc molecules[15]. We demonstrate that unglycosylated and anchorless recombinant full-length human PrP23-231 is able to dramatically inhibit human PrPSc amplification in vitro This inhibition occurs in a scrapie-infected cell model. We show that the inhibition may depend on direct interaction of the inhibitory recombinant PrP with human PrPSc using a capture strategy
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