Role of a Novel Topological Form of the Prion Protein in Prion Disease

摘要

Prion diseases are commonly associated with the presence of a conformationally altered form of the prion protein (PrPSc). However, there is mounting evidence that PrPSc is not directly toxic to neurons; it may require interaction with other gene products to induce a neurotoxic pathway. One candidate alternate neurotoxic PrP species is CtmPrP, which results from an alternate topological decision when the prion protein is translocated into the endoplasmic reticulum. We have identified mutations in the prion protein sequence which dramatically favors the production of CtmPrP (which under normal conditions is not detectable). We have established lines of transgenic mice which express CtmPrP designated Tg(L9R-3AV), and these mice develop a spontaneous neurological illness similar to prion disease Stewart et al. 2005. We are characterizing the phenotype of these mice to further our understanding of CtmPrP meditated neurotoxicity, which we believe will shed new light on the process of neurodegeneration in prion disease. We have also established cell lines expressing the L9R-3AV mutant PrP, which will allow us to develop in vitro models of CtmPrP-dependent cell toxicity. Task 1: Generation of anti-signal peptide antisera. Months 1-24. We have generated a specific antiserum to the signal peptide of PrP (amino acids 1-22), based on the observation that this amino acid sequence is not removed from CtmPrP, while it is efficiently removed form normal PrP. Therefore, an antibody specific for the signal peptide of PrP would be a highly specific tool for sensitive detection of CtmPrP in cells and tissues. A peptide corresponding to amino acids 14-27 of PrP was synthesized and injected into rabbits to generate a polyclonal serum. This antiserum was characterized for specificity using in vitro translated PrP and cell lysates expressing L9R- 3AV PrP.