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Virus‐induced alterations of membrane lipids affect the incorporation of PrP Sc into cells
Author(s) -
Avrahami Dana,
DayanAmouyal Yael,
Tal Saar,
Mincberg Michal,
Davis Claytus,
Abramsky Oded,
Gabizon Ruth
Publication year - 2008
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.21720
Subject(s) - internalization , lipid raft , immunostaining , biology , raft , microbiology and biotechnology , virus , membrane , endosome , membrane protein , chemistry , virology , biochemistry , immunohistochemistry , cell , immunology , organic chemistry , copolymer , polymer , intracellular
Prion diseases are fatal neurodegenerative disorders characterized by long incubation periods. To investigate whether concurrent diseases can modify the clinical outcome of prion‐affected subjects, we tested the effect of viral infection on the binding and internalization of PrP Sc , essential steps of prion propagation. To this effect, we added scrapie brain homogenate or purified PrP Sc to fibroblasts previously infected with minute virus of mice (MVM), a mouse parvovirus. We show here that the rate of incorporation of PrP Sc into MVM‐infected cells was significantly higher than that observed for naïve cells. Immunostaining of cells and immunoblotting of subcellular fractions using antibodies recognizing PrP and LysoTracker, a lysosomal marker, revealed that in both control and MVM‐infected cells the incorporated PrP Sc was associated mostly with lysosomes. Interestingly, floatation gradient analysis revealed that the majority of the PrP Sc internalized into MVM‐infected cells shifted toward raft‐containing low‐density fractions. Concomitantly, the MVM‐infected cells demonstrated increased levels of the glycosphingolipid GM1 (an essential raft lipid component) throughout the gradient and a shift in caveolin 1 (a raft protein marker) toward lighter membrane fractions compared with noninfected cells. Our results suggest that the effect of viral infection on membrane lipid composition may promote the incorporation of exogenous PrP Sc into rafts. Importantly, membrane rafts are believed to be the conversion site of PrP C to PrP Sc ; therefore, the association of exogenous PrP Sc with such membrane microdomains may facilitate prion infection. © 2008 Wiley‐Liss, Inc.