Lipid Rafts and Clathrin Cooperate in the Internalization of PrPC in Epithelial FRT CellsReport as inadecuate




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Background

The cellular prion protein PrPC plays a key role in the pathogenesis of Transmissible Spongiform Encephalopathies in which the protein undergoes post-translational conversion to the infectious form PrPSc. Although endocytosis appears to be required for this conversion, the mechanism of PrPC internalization is still debated, as caveolae-raft- and clathrin-dependent processes have all been reported to be involved.

Methodology-Principal Findings

We have investigated the mechanism of PrPC endocytosis in Fischer Rat Thyroid FRT cells, which lack caveolin-1 cav-1 and caveolae, and in FRT-cav-1 cells which form functional caveolae. We show that PrPC internalization requires activated Cdc-42 and is sensitive to cholesterol depletion but not to cav-1 expression suggesting a role for rafts but not for caveolae in PrPC endocytosis. PrPC internalization is also affected by knock down of clathrin and by the expression of dominant negative Eps15 and Dynamin 2 mutants, indicating the involvement of a clathrin-dependent pathway. Notably, PrPC co-immunoprecipitates with clathrin and remains associated with detergent-insoluble microdomains during internalization thus indicating that PrPC can enter the cell via multiple pathways and that rafts and clathrin cooperate in its internalization.

Conclusions-Significance

These findings are of particular interest if we consider that the internalization route-s undertaken by PrPC can be crucial for the ability of different prion strains to infect and to replicate in different cell lines.



Author: Daniela Sarnataro , Anna Caputo , Philippe Casanova, Claudia Puri, Simona Paladino, Simona S. Tivodar, Vincenza Campana, Carlo Ta

Source: http://plos.srce.hr/



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