Copper binding to PrPC may inhibit prion disease propagation

Although it has been well established that PrPC, the normal isoform of PrPs(Sc), is a copper-binding protein, the role of this metal in the function of PrPC as well as in prion disease pathology remains unclear. Here, we show that when scrapie-infected neuroblastoma cells were cultured in the presence of copper, the accumulation of PrPs(Sc) in these cells was markedly reduced. In addition, our results indicate that when normal neuroblastoma cells were cultured in the presence of copper ions, they could no longer bind and internalize PrPSc. In another set of experiments, copper was added to the drinking water of normal and scrap ie-infected hamsters. Our results show that administration of copper to normal hamsters induced cerebellar PrPC accumulation. Most important, a significant delay in prion disease onset was observed when scrapie-infected hamsters were treated with copper. As shown before for neuroblastoma cells, also in vivo most of the copper-induced accumulation of PrPC was intracellular. We hypothesized that PrPC internalization by copper may hinder PrPSc interaction with this molecule, and thereby affect prion disease propagation. (C) 2003 Elsevier B.V. All rights reserved.