Amyloid fibrils of mammalian prion protein are highly toxic to cultured cells and primary neurons.
A growing body of evidence indicates that small, soluble oligomeric species generated from a variety of proteins and peptides rather than mature amyloid fibrils are inherently highly cytotoxic. Here, we show for the first time that mature amyloid fibrils produced from full-length recombinant mammalian prion protein (rPrP) were highly toxic to cultured cells and primary hippocampal and cerebella neurons. Fibrils induced apoptotic cell death in a time- and dose-dependent manner. The toxic effect of fibrils was comparable with that exhibited by soluble small beta-oligomers generated from the same protein. Fibrils prepared from insulin were not toxic, suggesting that the toxic effect was not solely due to the highly polymeric nature of the fibrillar form. The cell death caused by rPrP fibrils or beta-oligomers was substantially reduced when expression of endogenous PrP(C) was down-regulated by small interfering RNAs. In opposition to the beta-oligomer and amyloid fibrils of rPrP, the monomeric alpha-helical form of rPrP stimulated neurite out-growth and survival of neurons. These studies illustrated that both soluble beta-oligomer and amyloid fibrils of the prion protein are intrinsically toxic and confirmed that endogenously expressed PrP(C) is required for mediating the toxicity of abnormally folded external PrP aggregates.
Medical Biotechnology Center, University of Maryland Biotechnology Institute, Baltimore, Maryland 21201.
Vera
V
Novitskaya
Medical Biotechnology Center, University of Maryland Biotechnology Institute, Baltimore, Maryland 21201.
Olga V
OV
Bocharova
National Institute for Medical Research, Physical Biochemistry Division, The Ridgeway, Mill Hill, London, NW7 1AA, United Kingdom.
Igor
I
Bronstein
Medical Biotechnology Center, University of Maryland Biotechnology Institute, Baltimore, Maryland 21201; Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201. Electronic address: Baskakov@umbi.umd.edu.
Ilia V
IV
Baskakov
D000682:Amyloid / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002478:Cells, Cultured; D006801:Humans; D007328:Insulin / Q000378:metabolism; D051379:Mice; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D011328:Prions / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity*; D020033:Protein Isoforms; D051381:Rats; D017208:Rats, Wistar
D000682:Amyloid; D007328:Insulin; D011328:Prions; D020033:Protein Isoforms