Misfolded prion proteins can cause neurodegenerative disease, but what purpose normal prions serve has been hard to pin down.
Now Adriano Aguzzi at the University Hospital of Zurich in Switzerland and his team show that the proteins are needed to maintain the myelin sheath that surrounds nerves and ensures that they function properly.
In the group's experiment, mice from four strains that were deficient in the prion protein all showed signs of neuropathy associated with demyelination. The damage was prevented when the protein was reintroduced to nerve cells but, surprisingly, not when it was reintroduced to Schwann cells, which produce myelin. Only variants of prion proteins that could be cleaved by enzymes could rescue the neuropathies, suggesting that enzyme processing of the prion is required for myelin maintenance.
The authors say that prion fragments may interact with receptors on Schwann cells to maintain the myelin sheath.
For a longer story on this research see http://go.nature.com/zK5sEq