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Glycosylphosphatidylinositol Anchor-Dependent Stimulation Pathway Required for Generation of Baculovirus-Derived Recombinant Scrapie Prion Protein▿ †

By Morikazu Imamura, Nobuko Kato, Miyako Yoshioka, Hiroyuki Okada, Yoshifumi Iwamaru, Yoshihisa Shimizu, Shirou Mohri, Takashi Yokoyama and Yuichi Murayama

Abstract

The pathogenic isoform (PrPSc) of the host-encoded cellular prion protein (PrPC) is considered to be an infectious agent of transmissible spongiform encephalopathy (TSE). The detailed mechanism by which the PrPSc seed catalyzes the structural conversion of endogenous PrPC into nascent PrPSc in vivo still remains unclear. Recent studies reveal that bacterially derived recombinant PrP (recPrP) can be used as a substrate for the in vitro generation of protease-resistant recPrP (recPrPres) by protein-misfolding cyclic amplification (PMCA). These findings imply that PrP modifications with a glycosylphosphatidylinositol (GPI) anchor and asparagine (N)-linked glycosylation are not necessary for the amplification and generation of recPrPSc by PMCA. However, the biological properties of PrPSc obtained by in vivo transmission of recPrPres are unique or different from those of PrPSc used as the seed, indicating that the mechanisms mediated by these posttranslational modifications possibly participate in reproductive propagation of PrPSc. In the present study, using baculovirus-derived recombinant PrP (Bac-PrP), we demonstrated that Bac-PrP is useful as a PrPC substrate for amplification of the mouse scrapie prion strain Chandler, and PrPSc that accumulated in mice inoculated with Bac-PrPres had biochemical and pathological properties very similar to those of the PrPSc seed. Since Bac-PrP modified with a GPI anchor and brain homogenate of Prnp knockout mice were both required to generate Bac-PrPres, the interaction of GPI-anchored PrP with factors in brain homogenates is essential for reproductive propagation of PrPSc. Therefore, the Bac-PMCA technique appears to be extremely beneficial for the comprehensive understanding of the GPI anchor-mediated stimulation pathway

Topics: Pathogenesis and Immunity
Publisher: American Society for Microbiology (ASM)
OAI identifier: oai:pubmedcentral.nih.gov:3067941
Provided by: PubMed Central
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