The proposed investigations are aimed to find evidence for the following:
PrPSc provides a stimulus for glial activation and cytokine production.
A-sheet formation and/or aggregation of PrP are important determinants for the pathological properties of PrPSc.
The pathological basis for neuronal death in transmissible spongiform encephalopathies (TSE) is unidentified. The pathology is characterized by accumulations of protease- resistant isoforms of the prion protein PrP (PrPSc), neurodegeneration with progressive loss, and vacuolation of neuronal processes. Astrocytosis and microglial activation occur in affected areas of the brain. Direct neurotoxicity of certain PrP peptides has been demonstrated in primary cultures of neuronal cells, but its effect on activation of glial cells is incompletely documented. The effect of activated glia on scrapie-infected neurons is also unknown. A knowledge of the molecular mechanisms responsible for neurodegeneration in TSE would also be informative for understanding other amyloid related conditions such as ageing and Alzheimer' s disease. Therefore, the following hypotheses will be investigated: 1. PrP or part of the molecule is critical in initiating the chain of events leading to neuronal degeneration. 2. Glial activation is an important step in this process. These questions will be approached with in vitro experiments by exposing primary cultures of CNS cells to PrPSc and PrP based peptides with distinct structural properties. The attention will be focused on the effects of exposure to PrP preparations on levels and timing of expression of cytokines and anti-inflammatory mediators in glial cells. For these experiments, primary cultures of mixed astrocyte/microglial constitution, and cultures enriched for astrocytes and microglial cells will be generated from newborn mice and rats. Peptides that differ in their potential to aggregate and form fibrils will be chosen, to investigate whether the structural state of the protein is critical in its pathological effects. Until now, such approaches to define the direct effects of amyloidogenic PrP protein on cells have only been fragmentary. The insight in the basic mechanisms of the pathology of prion disease to be obtained may indicate possible treatments of TSE, and possibly other amyloid-related neuronal disorders also. It may provide in vitro models for the assessment of such treatments.
Funding SchemeCSC - Cost-sharing contracts
82265 Fontenay Aux Roses
EH9 3JF Edinburgh