Zinc, copper, and carnosine attenuate neurotoxicity of prion fragment PrP106-126

Prion diseases are progressive neurodegenerative diseases that are associated with the conversion of normal cellular prion protein (PrPC) to abnormal pathogenic prion protein (PrPSC) by conformational changes. Prion protein is a metal-binding protein that is suggested to be involved in metal homeostasis. We investigated here the effects of trace elements on the conformational changes and neurotoxicity of synthetic prion peptide (PrP106-126). PrP106-126 exhibited the formation of beta-sheet structures and enhanced neurotoxicity during the aging process. The co-existence of Zn2+ or Cu2+ during aging inhibited b-sheet formation by PrP106-126 and attenuated its neurotoxicity on primary cultured rat hippocampal neurons. Although PrP106-126 formed amyloid-like fibrils as observed by atomic force microscopy, the height of the fibers was decreased in the presence of Zn2+ or Cu2+. Carnosine (beta-alanyl histidine) significantly inhibited both the beta-sheet formation and the neurotoxicity of PrP106-126. Our results suggested that Zn2+ and Cu2+ might be involved in the pathogenesis of prion diseases. It is also possible that carnosine might become a candidate for therapeutic treatments for prion diseases.