NR AXJK
AU Bessen,R.A.; Dlakic,W.; Martinka,S.; DeJoia,C.
TI The Role of the Neuromuscular Junction in Prion Agent Infection of Muscle Cells: A Model for Transynaptic Spread of the Prion Agent
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Oral Abstracts FC3.4
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Vortrag
AB
Skeletal muscle is one site of infection in prion diseases but the pathway and mechanism involved in infection has not been elucidated. In this study we used in vivo and in vitro models to investigate the role of the neuromuscular junction (NMJ) in entry of the prion agent into muscle cells. Direct unilateral inoculation of the HY strain of the transmissible mink encephalopathy agent into the hypoglossal nerve resulted in initial deposition of PrPsc in the nerves and skeletal muscle cells of the tongue. At the earliest time point of muscle cell infection, the distribution of PrPsc was found to be in a restricted, focal pattern within 60% to 90% of the PrPsc-positive cells and this pattern co-localized with markers for the NMJ in 47% to 89% of the PrPsc-positive cells. At clinical disease, PrPsc was widely distributed throughout the cytoplasm and the focal PrPsc pattern and co-localization with the NMJ was found in less than 7% of the PrPsc-positive muscle cells. These findings strongly suggest that upon initial entry of the prion agent into muscle cells that PrPsc is present at the NMJ and suggests that agent entry is via transynaptic spread from the motor nerve terminal.
To investigate the mechanism of prion infection of muscle cells in vitro, C2C12 cells (a myoblast cell line that can undergo differentiation into myotubes) were incubated with a scrapie brain homogenate or co-cultured with non-neuronal cell lines infected with 22L scrapie, but neither treatment resulted in infection of C2C12 cells. However, coculture of C2C12 cells with 22L scrapie-infected neuronal cell lines, N2a or GT1 cells, resulted in establishment of scrapie infection in myoblasts and myotubes. Co-culture with 22L scrapie neuronal cells lines in which myogenic differentiation was blocked did not result in infection of C2C12 myoblasts. These findings indicate that transfer of scrapie infection to muscle cells in vitro requires a neuronal cell and a differentiated muscle cell, which suggests that a NMJ between these cell types is necessary for transynaptic spread of scrapie infection. Studies that promote or inhibit NMJ formation in nerve-muscle co-cultures and these effects on scrapie infection of muscle cells will be presented.
AD Richard A. Bessen, Wendy Dlakic, Scott Martinka, Crista DeJoia, Montana State University, Veterinary Molecular Biology, USA
SP englisch
PO Schottland