Alzheimer's disease under strain

摘要

Acrucial event in the initiation of Alzheimer's disease is the formation of amyloid-β protein aggregates in the brain. Several studies indicate that these aggregates can acquire distinct shapes. Now, two papers published in Proceedings of the National Academy of Sciences demonstrate that each amyloid-β protein of a given shape can seed more aggregates of that same shape. This suggests that there are several variants of Alzheimer's disease, similar to influenza strains causing clinically distinct epidemics. The prion, which causes spongiform encephalopathies (neurodegenerative diseases such as Creutzfeldt-Jakob disease in humans and scrapie in sheep), remained shrouded in mystery for decades. But over the past 20 years, the 'protein-only' prion hypothesis has become widely accepted. This states that prions arise from an abnormal version of the cell-membrane protein PrP, called PrP~(Sc), which forms misfolded protein aggregates, or plaques.