The Roslin Institute
Abnormal protein accumulation in neurotoxicity and infection in TSEs and other neurodegenerative diseases.
The Barron Group performs a programme of research which aims to study the role of protein misfolding in neurodegenerative disease. In particular, the group focus on the relationship between abnormal PrP and the TSE infectious agent. Although the incidence of BSE and vCJD is declining in the UK, concern still exists surrounding subclinical disease in the population, and the associated risk of human-to-human transmission of disease via surgery and blood transfusion. Additionally, new atypical forms of ruminant TSE continue to be identified, and the associated risk of transmission to humans from these agents is still largely unknown. The Barron Group have particular interest in the relationship between abnormal prion protein (PrP) and TSE infectivity, and which specific abnormal PrP conformers may be infectious, neurotoxic or even protective. The group utilises biochemical, transcriptomic and proteomic technologies to examine in vivo and in vitro models of TSE and protein aggregation. The group has received funding from BBSRC, MRC, Defra and FSA.
Nature of the TSE agent. Although misfolded PrP is thought to be the sole component of the TSE infectious agent, the true relationship between abnormally folded forms of PrP and TSE infectivity are still unknown. The Barron Group are examining murine models in which the presence of abnormal PrP and TSE infectivity do not correlate to examine this relationship in more detail and determine whether a specific misfolded conformer may be associated with infectivity, rather than all misfolded aggregated form of the protein. Misfolded PrP can exist as oligomers, protofibrils and amyloid fibrils. Synthetic prions have also been created in vitro by several groups following fibrillisation of recombinant PrP, however these transmit with low efficiency suggesting that not all of the refolded PrP is infectious and a specific refolded conformer or aggregation state is required for disease transmission. Indeed recombinant PrP amyloid fibrils produced in Roslin can seed PrP amyloid accumulation in a transgenic model containing the P101L mutation in PrP, but do not cause TSE or generate TSE infectivity.
Protein misfolding and neurodegeneration. Using in vitro primary neuronal cell culture and whole brain organotypic slice culture the Barron Group are examining how cells respond to challenge with oligomeric or amyloid forms of misfolded protein. We have optimised methods for primary cell culture production and perform detailed analyses of cells using the newly acquired IMARIS software. Whole BOSCs have been maintained in culture for 8 months and fully characterised. We now aim to determine whether amyloid plaques can be seeded in these slices, or if the whole brain network and 3D support is required to sustain plaque production.
TSE Zoonosis. Sheep scrapie has been present in the environment for several hundred years without a co-current incidence of human TSE disease. It was therefore thought that ruminant TSEs were of little risk to humans. However following the outbreak of bovine spongiform encephalopathy (BSE) in the UK, a new variant of a human TSE (vCJD) was identified. The same TSE strain was responsible for BSE and vCJD, indicating that transmission from cattle to humans (zoonosis) had likely occurred. Using transgenic mice expressing human forms of the prion protein (PrP) we have been modelling the possible risk to humans from other ruminant TSEs. While sheep scrapie (both classical and atypical) did not transmit disease to these mice, BSE infection of sheep did produce an agent that transmitted more efficiently to human PrP transgenic mice than cattle BSE. These data highlight the possible risk to public health if BSE were to enter the sheep population. We continue to monitor new and emerging agents (such as chronic wasting disease in European deer) and assess the risk posed to humans.