Projects per year
The relationship between misfolded prion protein, infection and neurotoxicity is still not clearly understood. Previous work from our group demonstrated that inoculation of refolded recombinant PrP into transgenic mice expressing a proline to leucine mutation at PrP codon 101 (101LL) resulted in the presence and seeding of PrP amyloid plaques in the brain in the absence of TSE disease or replication of infectivity. Subsequent subpassages produced further amyloid seeding but no disease. Here we demonstrate clearly that abnormal forms of PrP can exist in the brain without causing a spongiform encephalopathy. PrP misfolding can also be separated from propagation of TSE infectivity as PrP amyloid accumulation can be induced in 101LL transgenic mice in the absence of infected inoculum. Interestingly throughout these experiments we observed that WT control mice were all negative for plaque deposition following inoculation. We could therefore hypothesise that in the absence of this point mutation the “healthy” brain can maintain homeostasis and efficiently clear any abnormal protein present. Further analysis of these intricate mechanisms is crucial to fully understand amyloid interactions within a healthy brain and whether elements such as age for example would be an important factor regarding homeostasis. To address these issues our investigations focus primarily on early time point mechanisms of cellular response after challenge with fluorescently labelled amyloid fibrils in both WT and PrPP101L models utilising both in vivo and in vitro models. We have currently developed two in vitro systems one with primary hippocampal cells isolated from E17 embryos and the second using organotypic brain slices. These systems are now fully developed and optimised and provide easily assessable models for investigating the trafficking and interactions of fluorescently labelled misfolded protein in vitro.