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PARIS -- A harmless form of the scrapie prion--an abnormally folded protein that leads to brain-degenerating diseases in humans, sheep, and cows--may help regulate nerve-cell functions through cellular signaling, researchers report in the 15 September issue of the international journal, Science.
While irregular prions are the known culprits behind incurable "spongey-brain" diseases, or transmissible spongiform encephalopathies (TSEs), the purpose of normal prions has remained mysterious until recently.
According to research teams directed by Odile Kellermann of the Institute Pasteur in Paris and Jean-Marie Launay of Hospital Lariboisire, unraveling the signal-carrying pathway of the normal prion (PrPc) will help reveal what triggers its activity, and later, how its corrupt form (PrPSc) wrecks cellular processes, causing the neurodegeneration of scrapie.
The non-pathogenic prion protein is not known to play a role in a specific cell function, researchers said. But, normal prions may fine-tune neuronal functions at the cellular level, since they are sited at nerve-cell surfaces, particularly in the outstretched arms of neurons called neurites, which collect and integrate information from other neurons.
Normal prions appear to participate in a signaling "cascade" that activates an enzyme called "Fyn," The Fyn enzyme is a tyrosine kinase capable of stimulating multiple intracellular events that change, for example, a cell's responsiveness to other nervous stimuli, said Odile Kellermann and her collaborator, Sophie Mouillet-Richard, lead author of the Science paper.
The research team identified two forms of a caveolin-1 protein, and possibly another protein, clathrin, which also appeared to participate in the activation of Fyn. Other cellular partners
Contact: Ginger Pinholster
American Association for the Advancement of Science