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Updated: Jun 7, 2026
Investigating the Spreading and Toxicity of Prion-like Proteins Using the Metazoan Model Organism C. elegans
Published on: January 8, 2015
Compartment-restricted biotinylation reveals novel features of prion protein metabolism in vivo
Amy B Emerman1, Zai-Rong Zhang, Oishee Chakrabarti
1Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Abstract:
Proteins are often made in more than one form, with alternate versions sometimes residing in different cellular compartments than the primary species. The mammalian prion protein (PrP), a cell surface GPI-anchored protein, is a particularly noteworthy example for which minor cytosolic and transmembrane forms have been implicated in disease pathogenesis. To study these minor species, we used a selective labeling strategy in which spatially restricted expression of a biotinylating enzyme was combined with asymmetric engineering of the cognate acceptor sequence into PrP. Using this method, we could show that even wild-type PrP generates small amounts of the (Ctm)PrP transmembrane form. Selective detection of (Ctm)PrP allowed us to reveal its N-terminal processing, long half-life, residence in both intracellular and cell surface locations, and eventual degradation in the lysosome. Surprisingly, some human disease-causing mutants in PrP selectively stabilized (Ctm)PrP, revealing a previously unanticipated mechanism of (Ctm)PrP up-regulation that may contribute to disease. Thus, spatiotemporal tagging has uncovered novel aspects of normal and mutant PrP metabolism and should be readily applicable to the analysis of minor topologic isoforms of other proteins.
Insights
Spatiotemporal tagging reveals that wild-type prion protein (PrP) produces a minor transmembrane form, (Ctm)PrP. Disease-causing PrP mutants stabilize (Ctm)PrP, suggesting a novel disease mechanism.
Area of Science:
- Molecular Biology
- Cell Biology
- Neuroscience
Background:
- Proteins can exist in multiple forms, with different cellular locations.
- Minor forms of the mammalian prion protein (PrP), such as cytosolic and transmembrane (Ctm)PrP, are linked to disease pathogenesis.
Purpose of the Study:
- To investigate the metabolism and cellular localization of minor prion protein (PrP) topologic isoforms.
- To explore the role of the transmembrane form of PrP ((Ctm)PrP) in disease.
Main Methods:
- Utilized a selective labeling strategy combining spatially restricted biotinylation and engineered acceptor sequences in PrP.
- Developed methods for the selective detection and analysis of (Ctm)PrP.
Main Results:
- Demonstrated that wild-type PrP generates small amounts of the (Ctm)PrP transmembrane form.
- Characterized the N-terminal processing, long half-life, intracellular and cell surface localization, and lysosomal degradation of (Ctm)PrP.
- Identified that certain human disease-associated PrP mutants selectively stabilize (Ctm)PrP, leading to its up-regulation.
Conclusions:
- Spatiotemporal tagging is a powerful tool for studying minor protein isoforms.
- Normal PrP undergoes metabolism involving the generation and degradation of (Ctm)PrP.
- Stabilization of (Ctm)PrP by disease-associated mutants represents a novel disease mechanism.
