NR APAG
AU Watt,N.T.; Hooper,N.M.
TI A Failure of Proteolytic Processing to PrP-21 in the Prion Protein Correlates with a Compromised Response to Oxidative Stress
QU International Conference - Prion diseases: from basic research to intervention concepts - TSE-Forum, 08.10.-10.10.2003, Gasteig, München - Poster session - BR-38
PT Konferenz-Poster
AB Whilst the function of the full length prion protein (PrP) remains an enigma, a number of possible roles have been proposed including; metal binding, anti-oxidant protection and signal tranduction. Mutant forms of PrP were made in which parts of the N-terminus were modified. Significantly, the octapeptide repeat region in this part of the protein is known to be able to bind copper or zinc. This metal binding being important in the anti-oxidant protection afforded by PrP. Constructs were generated whereby this region was completely removed (DOct), a further nine repeats were included (PG14) or point mutations inserted to affect the metal binding capability of the protein (H68/76G). Assays of superoxide dismutase, glutathione peroxidase, viability and intracellular radical formation were performed on each of the mutants and compared with levels found in both wild-type PrP expressing cells and cells which expressed minimal levels of the protein. Cells expressing the DOct mutant responded particularly poorly to oxidative stress with significant reductions in viability (p<0.001), increased radical formation (p<0.001) and reduced anti-oxidant enzyme activity (P<0.05). PG14 showed similar reductions though H68 showed only minor reductions in the measurements made compared with the wild-type protein. Endoproteolysis of PrP generates PrP-21, a C-terminal portion of the protein which no longer contains the N-terminal octarepeat. When levels of PrP-21 were measured in each cell type, DOct was unable to generate this proteolytic product. This may indicate that either PrP-21, or the N-terminal fragment that is cleaved off, may be important in regulating the cellular response to oxidative stress mediated by the prion protein.
AD N.T. Watt, N.M. Hooper, School of Biochemistry and Molecular Biology, University of Leeds, Leeds, LS2 9JT. UK
SP englisch
PO Deutschland