LA JOLLA, CA, August 9, 2012 Many of us are familiar with prion disease from its most startling and unusual incarnationsthe outbreaks of "mad cow" disease (bovine spongiform encephalopathy) that created a crisis in the global beef industry. Or the strange story of Kuru, a fatal illness affecting a tribe in Papua New Guinea known for its cannibalism. Both are forms of prion disease, caused by the abnormal folding of a protein and resulting in progressive neurodegeneration and death.
While exactly how the protein malfunctions has been shrouded in mystery, scientists at The Scripps Research Institute now report in the journal Proceedings of the National Academy of Sciences (PNAS) that reducing copper in the body delays the onset of disease. Mice lacking a copper-transport gene lived significantly longer when infected with a prion disease than did normal mice.
"This conclusively shows that copper plays a role in the misfolding of the protein, but is not essential to that misfolding," said Scripps Research Professor Michael Oldstone, who led the new study.
"We've known for many years that prion proteins bind copper," said Scripps Research graduate student Owen Siggs, first author of the paper with former Oldstone lab member Justin Cruite. "But what scientists couldn't agree on was whether this was a good thing or a bad thing during prion disease. By creating a mutation in mice that lowers the amount of circulating copper by 60 percent, we've shown that reducing copper can delay the onset of prion disease."
Unlike most infections, which are caused by bacteria, viruses, or parasites, prion disease stems from the dysfunction of a naturally occurring protein.
"We all contain a normal prion protein, and when that's converted to an abnormal prion protein, you get a chronic nervous system disease," said Oldstone. "That occurs genetically (spontaneously in some people) or is acquired by pass
|Contact: Mika Ono|
Scripps Research Institute