‘Harmless’ prion protein linked to Alzheimer’s disease
Non-infectious prion proteins found in the brain may contribute to Alzheimer’s disease, researchers have found.
The surprising new results, reported this week in Nature1, show that normal prion proteins produced naturally in the brain interact with the amyloid-β peptides that are hallmarks of Alzheimer’s disease. Blocking this interaction in preparations made from mouse brains halted some neurological defects caused by the accumulation of amyloid-β peptide. It was previously thought that only infectious prion proteins, rather than their normal, non-infectious counterparts, played a role in brain degeneration.
The results have yet to be confirmed in humans, but suggest that targeting the non-infectious prion protein (PrPc) could provide an alternative route to treating Alzheimer’s disease. “The need is huge,” says Paul Aisen, an Alzheimer’s researcher based at the neurosciences department of the University of California, San Diego. “And it’s great news for the field when a new idea is brought forth with strong evidence that can lead to new therapeutic strategies.”
Proteins misbehaving
Alzheimer’s disease has long been linked to the build-up of amyloid-β peptides, first into relatively short chains known as oligomers, and then eventually into the long, sticky fibrils that form plaques in the brain. The oligomeric form of the peptide is thought to be toxic, but exactly how it acts in the brain is unknown.
Stephen Strittmatter and his colleagues at Yale University in New Haven, Connecticut searched for brain cell proteins that interact with amyloid-β oligomers. To their surprise, they found PrPc, the normal, non-infectious prion protein.
Normal prion proteins are produced naturally in the brain, but can cause disease when they come into contact with an infectious form of the protein (PrPSc) that folds into an unusual conformation. These infectious prions convert innocuous prion proteins into the infectious form, which forms clumps and leads to neurodegenerative diseases, such as variant Creu