Recombinant human prion protein fragment 90-231, a useful model to study prion neurotoxicity

Transmissible spongiform encephalopathies (TSE), or prion diseases, are a group of fatal neurodegenerative disorders of animals and humans. Human diseases include Creutzfeldt-Jakob (CJD) and Gerstmann-Straussler-Scheinker (GSSD) diseases, fatal familial insomnia, and Kuru. Human and animal TSEs share a common histopathology with a pathognomonic triad: spongiform vacuolation of the grey matter, neuronal death, glial proliferation, and, more inconstantly, amyloid deposition. According to the ‘‘protein only’’ hypothesis, TSEs are caused by a unique post-translational conversion of normal, host-encoded, protease-sensitive prion protein (PrPsen or PrPC) to an abnormal disease-associated isoform (PrPres or PrPSc). To investigate the molecular mechanism of neurotoxicity induced by PrPSc we developed a protocol to obtain millimolar amounts of soluble recombinant polypeptide encompassing the amino acid sequence 90–231 of human PrP (hPrP90–231). This protein corresponds to the protease-resistant prion protein fragment that originates after amino-terminal truncation. Importantly, hPrP90–231 has a flexible backbone that, similar to PrPC, can undergo to structural rearrangement. This peptide, structurally resembling PrPC, can be converted in a PrPSc-like conformation, and thus represents a valuable model to study prion neurotoxicity. In this article we summarized our experimental evidence on the molecular and structural mechanisms responsible of hPrP90–231 neurotoxicity on neuroectodermal cell line SHSY5Y and the effects of some PrP pathogen mutations identified in familial TSE.