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The cellular isoform of the prion protein, PrPc, is associated with caveolae in mouse neuroblastoma (N2a) cells
1Department of Zoology, University College Dublin, Belfield, Ireland.
Abstract:
A major component of the infectious particle causing spongiform encephalopathies or prion diseases is an aberrant isoform (PrPSc) of a glycosyl-phosphatidylinositol (GPI)-anchored cell surface protein, PrPC. The cellular processes involved in the formation of PrPSc are unclear but involve the internalization of PrPC prior to conversion. Here, we demonstrate that PrPC is associated with caveolin, a structural protein component of caveolae. We show that PrPC and caveolin share similar detergent characteristics and copurify in linear sucrose gradients. PrPC was protected from proteinase K digestion in the caveolin fraction but solubilizing the caveolae prior to proteinase K digestion rendered PrPC susceptible to proteinase K digestion. Our results indicate a physical association between PrPC and caveolin in N2a cells. The implication of these results in relation to prion biogenesis is discussed.
Insights
Prion protein (PrPC) interacts with caveolin, a protein found in caveolae. This association protects PrPC from degradation, suggesting a role in prion disease formation.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Prion diseases are linked to an abnormal prion protein isoform (PrPSc).
- The cellular mechanisms of PrPSc formation, including PrPC internalization, remain unclear.
- PrPC is a GPI-anchored cell surface protein.
Purpose of the Study:
- To investigate the association between PrPC and caveolin.
- To explore the role of this association in prion biogenesis.
Main Methods:
- Biochemical analysis of PrPC and caveolin in N2a cells.
- Copurification studies using linear sucrose gradients.
- Proteinase K digestion assays before and after caveolae solubilization.
Main Results:
- PrPC and caveolin exhibit similar detergent properties and copurify.
- PrPC within the caveolin fraction is protected from proteinase K digestion.
- Solubilizing caveolae makes PrPC susceptible to proteinase K digestion, indicating a physical association.
Conclusions:
- A physical association exists between PrPC and caveolin in N2a cells.
- This interaction may play a significant role in the biogenesis of prions and the pathogenesis of prion diseases.