NR AXWJ
AU Singh,N.; Maradumane,M.; Basu,S.; Luo,X.
TI Modulation of PK-resistant PrP in Cells and Infectious Brain Homogenate by Redox-Iron: Implications for Prion Replication and Disease Pathogenesis
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Pathology and Pathogenesis P03.107
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Poster
AB
Background: The principal agent responsible for all prion disorders is a ß-sheet rich form of the cellular prion protein (PrPc) termed PrP-scrapie (PrPsc). Once initiated, PrPsc is self replicating and toxic to neuronal cells. Recently, markers of oxidative stress and increased ferrous (Fe2+) and ferric (Fe3+) iron have been reported in the brains of scrapie-infected mice and Creutzfeltd-Jakob disease affected human brains. The trigger leading to brain iron imbalance, however, remains unclear.
Aims: The objective of this study is to evaluate the role of redox iron in prion disease pathogenesis.
Methods: Cell culture models and prion disease affected human and mouse brain tissue were used for this study.
Results We provide evidence that prion protein (PrPc) binds iron, a characteristic likely to modulate its susceptibility to oxidative damage and contribute to altered levels of total and redox-active iron in diseased brains. Using PrPc expressing neuroblastoma cells (PrPc-cells), we demonstrate that exposure to ferrous chloride (FeCl2) induces the
conversion of PrPc to a PrPsc-like form (AggrPrP) that co-aggregates with ferritin and resembles brain derived PrPsc in characteristics such as insolubility in non-ionic detergents, non-reactivity with 3F4 unless denatured, resistance to proteinase-K (PK), and limited propagation in culture. Thus, addition of FeCl2 treated cell pellet to fresh
cells induces the generation of additional AggrPrP, simulating AggrPrP propagation in the absence of infectious brain homogenate. On the other hand, depletion of iron from prion disease affected human and mouse brains and mouse neuroblastoma (ScN2a) cells reduces the amount of PK-resistant PrPsc by 4-10-fold, though PK-resistance of ferritin is not altered significantly by this treatment. Discussion Our results suggest that the iron binding characteristic of PrPc renders it susceptible to redox-iron mediated damage, resulting in the generation of a PrPsc-like molecule that is itself redox-active and induces a similar change in additional PrPc. Combined with the fact that depletion of iron from infectious brain homogenates and cells reduces PK-resistant PrPsc, these results suggest that redox-iron is involved in the generation, propagation, and stability of PK-resistant PrPsc. It is plausible that the PK-resistant characteristic of PrPsc is derived through its association with ferritin, iron being an important mediator of this complex.
AD N. Singh, M. Maradumane, S. Basu, X. Luo, Case Western Reserve University, Pathology, USA
SP englisch
PO Schottland