NR AXMU
AU Garofoli,A.; Dossena,S.; Forloni,G.; Chiesa,R.
TI Neurodegeneration in a Transgenic Mouse Model of Inherited Prion Disease Occurs in the Absence of Ubiquitin-proteasome System Impairment
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Pathology and Pathogenesis P03.162
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Poster
AB
Impairment of the ubiquitin-proteasome system (UPS) is proposed to play a pathogenic role in prion diseases. In this study we monitored the functional status of the UPS in Tg(PG14) mice, which express a nine-octapeptide insertion associated with an inherited prion disease. These mice produce a misfolded form of the mutant protein in their brains. As this form accumulates the mice develop a fatal neurological illness characterized by massive apoptosis of cerebellar granule neurons. To test whether neurodegeneration in Tg(PG14) mice was associated with reduced function of the UPS, we generated mice co-expressing PG14 PrP and a green fluorescent protein (GFP) reporter substrate of the UPS (UbG76V-GFP) (Lindsten et al., Nat Biotechnol 21, 897-902, 2003).
Tg(PG14) mice were crossed with two independent lines of UbG76V-GFP mice, which differ in basal levels of reporter expression, to produce Tg(PG14+/-)/UbG76V-GFP and Tg(PG14-/-)/UbG76V-GFP offspring. As an additional control, we generated Tg(WT)/UbG76V-GFP mice, overexpressing transgenically-encoded wild-type PrP. Mice of the different genotypes were culled at various stages of the Tg(PG14) illness
(i.e. 90, 150, 250 and >300 days of age), and analyzed by Western blot and immunohistochemistry with anti-GFP antibodies. No increased levels of the GFP reporter were found in the brains of Tg(PG14+/-)/UbG76V-GFP mice compared to Tg(PG14-/-)/UbG76V-GFP controls. Some GFP-immunopositivity was detected in Purkinje neurons of the cerebellum of double transgenic mice expressing higher basal level of the reporter. However, this was detected also in Tg(PG14-/-)/UbG76V-GFP and Tg(WT)/UbG76V-GFP mice. Our results indicate that the neurodegeneration caused by accumulation of mutant PrP is not associated with dysfunction of the ubiquitin-proteasome system, arguing against the hypothesis that perturbation of the proteasomal pathway plays a pathogenic role in inherited prion diseases.
AD A. Garofoli, S. Dossena, R. Chiesa, Dulbecco Telethon Institute-Mario Negri Institute, Neuroscience, Italy; G. Forloni, Mario Negri Institute, Neuroscience, Italy
SP englisch
PO Schottland