http://www.nature.com/news/misfolded...o-cell-1.11838

The catastrophic damage wreaked by a rogue protein involved in Parkinsons' disease has been tracked by researchers, in work that might help to reinvigorate an old treatment strategy to slow the condition.

A team led by Virginia Lee, a neurobiologist at the University of Pennsylvania in Philadelphia, injected a misfolded synthetic version of the protein α-synuclein into the brains of normal mice and saw the key characteristics of Parkinson’s disease develop and progressively worsen. The study, published today in Science1, suggests that the disease is spread from one nerve cell to another by the malformed protein, rather than arising spontaneously in the cells.