Work

Identification of Anti-prion Compounds using a Novel Cellular Assay

Year: 2016

Type: article

Abstract: Prion diseases are devastating neurodegenerative disorders with no known cure. One strategy for developing therapies for these diseases is to identify compounds that block conversion of the cellular form of the prion protein (PrP C ) into the infectious isoform (PrP Sc ). Most previous efforts to discover such molecules by high-throughput screening methods have utilized, as a read-out, a single kind of cellular assay system: neuroblastoma cells that are persistently infected with scrapie prions. Here, we describe the use of an alternative cellular assay based on suppressing the spontaneous cytotoxicity of a mutant form of PrP (Δ105–125). Using this assay, we screened 75,000 compounds, and identified a group of phenethyl piperidines (exemplified by LD7), which reduces the accumulation of PrP Sc in infected neuroblastoma cells by >90% at low micromolar doses, and inhibits PrP Sc -induced synaptotoxicity in hippocampal neurons. By analyzing the structure-activity relationships of 35 chemical derivatives, we defined the pharmacophore of LD7, and identified a more potent derivative. Active compounds do not alter total or cell-surface levels of PrP C , and do not bind to recombinant PrP in surface plasmon resonance experiments, although at high concentrations they inhibit PrP Sc -seeded conversion of recombinant PrP to a misfolded state in an in vitro reaction (RT-QuIC). This class of small molecules may provide valuable therapeutic leads, as well as chemical biological tools to identify cellular pathways underlying PrP Sc metabolism and PrP C function.

Source: Journal of Biological Chemistry

DOI: 10.1074/jbc.m116.745612