Related Experiment Video
Updated: May 24, 2026
Isolation of Soluble and Insoluble PrP Oligomers in the Normal Human Brain
Published on: October 3, 2012
Mouse prion protein (PrP) segment 100 to 104 regulates conversion of PrP(C) to PrP(Sc) in prion-infected
Hideyuki Hara1, Yuko Okemoto-Nakamura, Fumiko Shinkai-Ouchi
1Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Tokyo, Japan.
Abstract:
Prion diseases are characterized by the replicative propagation of disease-associated forms of prion protein (PrP(Sc); PrP refers to prion protein). The propagation is believed to proceed via two steps; the initial binding of the normal form of PrP (PrP(C)) to PrP(Sc) and the subsequent conversion of PrP(C) to PrP(Sc). We have explored the two-step model in prion-infected mouse neuroblastoma (ScN2a) cells by focusing on the mouse PrP (MoPrP) segment 92-GGTHNQWNKPSKPKTN-107, which is within a region previously suggested to be part of the binding interface or shown to differ in its accessibility to anti-PrP antibodies between PrP(C) and PrP(Sc). Exchanging the MoPrP segment with the corresponding chicken PrP segment (106-GGSYHNQKPWKPPKTN-121) revealed the necessity of MoPrP residues 99 to 104 for the chimeras to achieve the PrP(Sc) state, while segment 95 to 98 was replaceable with the chicken sequence. An alanine substitution at position 100, 102, 103, or 104 of MoPrP gave rise to nonconvertible mutants that associated with MoPrP(Sc) and interfered with the conversion of endogenous MoPrP(C). The interference was not evoked by a chimera (designated MCM2) in which MoPrP segment 95 to 104 was changed to the chicken sequence, though MCM2 associated with MoPrP(Sc). Incubation of the cells with a synthetic peptide composed of MoPrP residues 93 to 107 or alanine-substituted cognates did not inhibit the conversion, whereas an anti-P8 antibody recognizing the above sequence in PrP(C) reduced the accumulation of PrP(Sc) after 10 days of incubation of the cells. These results suggest the segment 100 to 104 of MoPrP(C) plays a key role in conversion after binding to MoPrP(Sc).
Insights
This study reveals that specific residues (100-104) in mouse prion protein (MoPrP) are crucial for converting normal prion protein (PrP(C)) into its disease-associated form (PrP(Sc)) after binding. Antibodies targeting this region effectively reduce PrP(Sc) accumulation, highlighting a key step in prion disease propagation.
Area of Science:
- Neuroscience
- Molecular Biology
- Prion Disease Research
Background:
- Prion diseases involve the replication of abnormal prion protein (PrP(Sc)) from normal prion protein (PrP(C)).
- This process is thought to occur in two steps: binding of PrP(C) to PrP(Sc) and subsequent conversion.
- The specific molecular interactions governing this conversion remain incompletely understood.
Purpose of the Study:
- To investigate the role of a specific mouse prion protein (MoPrP) segment (92-107) in the two-step prion propagation model.
- To identify critical residues within this segment essential for PrP(C) to PrP(Sc) conversion.
- To explore potential therapeutic targets by examining the effect of antibodies on PrP(Sc) formation.
Main Methods:
- Utilized prion-infected mouse neuroblastoma cells (ScN2a).
- Created chimeric prion proteins by exchanging mouse PrP segments with chicken PrP sequences.
- Introduced alanine substitutions at specific MoPrP residues and assessed conversion and PrP(Sc) association.
- Tested the inhibitory effects of synthetic peptides and anti-PrP antibodies on PrP(Sc) accumulation.
Main Results:
- MoPrP residues 99-104 were essential for conversion to the PrP(Sc) state, while residues 95-98 were exchangeable.
- Alanine substitutions at positions 100, 102, 103, or 104 resulted in nonconvertible mutants that interfered with endogenous PrP(C) conversion.
- An antibody recognizing MoPrP residues 93-107 significantly reduced PrP(Sc) accumulation, indicating the segment's role in conversion post-binding.
Conclusions:
- The MoPrP segment 100-104 is critical for the conversion step in prion propagation, following initial binding to PrP(Sc).
- This segment represents a key target for therapeutic intervention in prion diseases.
- The findings provide crucial insights into the molecular mechanism of prion replication.
