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Title: Discovery of a novel, monocationic, small-molecule inhibitor of scrapie prion accumulation in cultured sheep microglia and rov cells PLoS one

Author
item STANTON, JAMES - Washington State University
item Schneider, David
item DINKEL, KELCEY - Washington State University
item BALMER, BETHANY - Washington State University
item BASZLER, TIMOTHY - Washington State University
item MATHISON, BRUCE - Washington State University
item BOYKIN, DAVID - Georgia State University

Submitted to: Antimicrobial Agents and Chemotherapy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2012
Publication Date: 11/30/2012
Citation: Stanton, J.B., Schneider, D.A., Dinkel, K.D., Balmer, B.F., Baszler, T.V., Mathison, B.A., Boykin, D.W. 2012. Discovery of a novel, monocationic, small-molecule inhibitor of scrapie prion accumulation in cultured sheep microglia and rov cells PLoS one. Antimicrobial Agents and Chemotherapy. PloSone 7(11):e51173.

Interpretive Summary: Scrapie, an invariably fatal disorder of sheep and goats, is endemic in the United States, but subject to an intensive federal/state/industry eradication program. Infected animals have a long incubation period, usually lasting for 2–6 years. During which affected animals remain clinically normal, but can spread the disease to flockmates. The central feature of scrapie is the conversion of a normal cellular prion protein into an abnormal, disease-associated state through a misfolding event. The abnormal prion protein, PrPSc, is eventually disseminated to the brain, where it accumulates in a number of cell types, including microglial cells. Previously, the investigators established a primary sheep microglial cell culture system that accumulates PrPSc, which is the only PrPSc-permissive cell culture system derived from sheep or goats. Using this cell culture system it was discovered that an anti-viral compound inhibited PrPSc accumulation. The anti-PrPSc activity was also confirmed in a second cell type. No evidence was found to support that inhibition of normal prion protein expression was the mechanism of action. Nor was there evidence that the anti-viral effects were directly related to the anti-PrPSc effects. This work moves forward our knowledge of anti-PrPSc compounds, which in the future can be used to further elucidate the cellular pathogenesis involved with cellular accumulation of PrPSc.

Technical Abstract: Prion diseases, including sheep scrapie are neurodegenerative diseases with the fundamental pathogenesis involving conversion of normal cellular prion protein (PrPC) to disease-associated prion protein (PrPSc). An aromatic monocationic furamidine analogue (DB772), which has previously demonstrated anti-pestiviral activity and represents a chemical category previously untested for anti-prion activity, inhibited PrPSc accumulation in primary sheep microglial cell cultures (PRNP 136VV/154RR/171QQ) and Rov9 cultures (VRQ-ovinized RK13 cells). As predicted, DB772 also inhibited pestivirus in both cell types. PRNP transcripts and total PrP protein concentrations within cell lysates were not decreased; thus, decreased PrPC expression is not the mechanism of PrPSc inhibition. PrPSc accumulation was more resistant to DB772, suggesting that the anti-PrPSc activity was independent of anti-pestivirus activity. The anti-PrPSc selectivity index in cell culture was approximately 4.6 in microglia and 5.5 in Rov9 cells. The results describe a new chemical category that inhibits PrPSc accumulation in primary sheep microglia and Rov9 cells, and can be used for future studies into the treatment and mechanism of prion diseases.