NR AXQM
AU Kristiansen,M.; Deriziotis,P.; Dimcheff,D.E.; Jackson,G.S.; Ovaa,H.; Naumann,H.; Clarke,A.R.; van Leeuwen,F.W.B.; Menendez-Benito,V.; Dantuma,N.P.; Portis,J.L.; Collinge,J.; Tabrizi,S.J.
TI Disease-associated Prion Protein Oligomers Inhibit the 26S Proteasome
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Oral Abstracts FC4.4
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Vortrag
AB
Background: The mechanism of cell death in prion disease is unknown but is associated with the production of a misfolded conformer of the prion protein. Our
previous work has suggested a clear role for ubiquitin proteasome system (UPS) dysfunction in the pathogenesis of prion disease (Kristiansen et al., 2005, JBC). Degradation of intracellular proteins via the UPS is a complex and tightly regulated process that plays a critical role in cellular processes. The 26S proteasome consists of a 20S proteolytic core (14 a-subunits and 14 ß-subunits) complexed at one or both ends with a 19S regulatory complex. The proteolytic activity of the 20S proteasome
resides in its two inner ß rings.
Aims: This study aimed to examine further the nature of the PrP species responsible for neurotoxicity, to evaluate the role of the UPS in prion disease pathogenesis, and to investigate whether there was a direct mechanistic link between the two.
Methods: Proteasome GFP-reporter substrates, fluorogenic peptides, and a novel activity probe for the proteasome ß-subunits were used to demonstrate the effect of disease-associated prion protein in pure 26S proteasome and cell lines. To assess whether UPS impairment also occurred in prion-mediated neurodegeneration in vivo, we prion-infected a transgenic mouse model that allows the functional status of the UPS to be monitored (Lindsten et al., 2003, Nat. Biotech.).
Results: We report that disease-associated prion protein specifically inhibits the key proteolytic ß-subunits of 26S proteasome. This was demonstrated both in pure 26S proteasome and 3 different cell lines. By challenge with recombinant prion and other amyloidogenic proteins, we demonstrate that only the prion protein in a non-native ßsheet conformation inhibits the 26S proteasome at stoichiometric concentrations. Preincubation with an antibody specific for aggregation intermediates abrogates this inhibition, consistent with an oligomeric species mediating this effect. Prion infection caused specific inhibition of the UPS in our GFP-proteasome reporter transgenic mice together with accumulation of ubiquitin deposits. To the best of our knowledge, this is the first reported in vivo evidence for functional proteasome impairment in a neurodegenerative disease characterized by protein aggregation.
Conclusion: Together, these data suggest a mechanism for intracellular neurotoxicity mediated by oligomers of misfolded prion protein.
AD M. Kristiansen, J. Collinge, Institute of Neurology, MRC Prion Unit/Dept of Neurodegenerative Disease, UK; P. Deriziotis, S.J. Tabrizi, Institute of Neurology, Department of Neurodegenerative Disease, UK; D.E. Dimcheff, J.L. Portis, NIAID, NIH Rocky Mountain Laboratories, Laboratory of Persistent Viral Diseases, USA; G.S. Jackson, H. Naumann, A.R. Clarke, Institute of Neurology, MRC Prion Unit, UK; H. Ovaa, F.W.B. van Leeuwen, Netherlands Cancer Institute, Division of Cellular Biochemistry, Netherlands; V. Menendez-Benito, N.P. Dantuma, Karolinska Institutet, Department of Cell and Molecular Biology, Sweden
SP englisch
PO Schottland