title: The mechanism of membrane disruption by cytotoxic amyloid oligomers formed by prion protein(106-126) is dependent on bilayer composition.
abstract: The formation of fibrillar aggregates has long been associated with neurodegenerative disorders such as Alzheimer and Parkinson diseases. Although fibrils are still considered important to the pathology of these disorders, it is now widely understood that smaller amyloid oligomers are the toxic entities along the misfolding pathway. One characteristic shared by the majority of amyloid oligomers is the ability to disrupt membranes, a commonality proposed to be responsible for their toxicity, although the mechanisms linking this to cell death are poorly understood. Here, we describe the physical basis for the cytotoxicity of oligomers formed by the prion protein (PrP)-derived amyloid peptide PrP(106-126). We show that oligomers of this peptide kill several mammalian cells lines, as well as mouse cerebellar organotypic cultures, and we also show that they exhibit antimicrobial activity. Physical perturbation of model membranes mimicking bacterial or mammalian cells was investigated using atomic force microscopy, polarized total internal reflection fluorescence microscopy, and NMR spectroscopy. Disruption of anionic membranes proceeds through a carpet or detergent model as proposed for other antimicrobial peptides. By contrast, when added to zwitterionic membranes containing cholesterol-rich ordered domains, PrP(106-126) oligomers induce a loss of domain separation and decreased membrane disorder. Loss of raft-like domains may lead to activation of apoptotic pathways, resulting in cell death. This work sheds new light on the physical mechanisms of amyloid cytotoxicity and is the first to clearly show membrane type-specific modes of action for a cytotoxic peptide.
authors.affiliation: Molecular Structure and Function Program, The Hospital for Sick Children, Toronto, Ontario M5G 1X8; Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8.
authors.forename: Patrick
authors.initials: P
authors.lastname: Walsh
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario M5S 3E1.
authors.forename: Gillian
authors.initials: G
authors.lastname: Vanderlee
authors.affiliation: Molecular Structure and Function Program, The Hospital for Sick Children, Toronto, Ontario M5G 1X8; Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8.
authors.forename: Jason
authors.initials: J
authors.lastname: Yau
authors.affiliation: Department of Medicine, Division of Neurology, University of Alberta, Edmonton, Alberta T6G 2G3, Canada.
authors.forename: Jody
authors.initials: J
authors.lastname: Campeau
authors.affiliation: Department of Medicine, Division of Neurology, University of Alberta, Edmonton, Alberta T6G 2G3, Canada.
authors.forename: Valerie L
authors.initials: VL
authors.lastname: Sim
authors.affiliation: Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8; Institute of Biomaterials and Biomedical Engineering, Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario M5S 3E1.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Yip
authors.affiliation: Molecular Structure and Function Program, The Hospital for Sick Children, Toronto, Ontario M5G 1X8; Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8. Electronic address: ssharpe@sickkids.ca.
authors.forename: Simon
authors.initials: S
authors.lastname: Sharpe
mesh_terms: D000682:Amyloid / Q000737:chemistry*; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry; D002462:Cell Membrane / Q000737:chemistry; D002531:Cerebellum / Q000473:pathology; D002784:Cholesterol / Q000737:chemistry; D003902:Detergents / Q000737:chemistry; D004926:Escherichia coli / Q000254:growth & development; D008051:Lipid Bilayers / Q000737:chemistry; D008055:Lipids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008810:Mice, Inbred C57BL; D008826:Microbial Sensitivity Tests; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D009924:Organ Culture Techniques; D016716:PC12 Cells; D010446:Peptide Fragments / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry; D011328:Prions / Q000737:chemistry*; D051381:Rats
chemical_list: D000682:Amyloid; D023181:Antimicrobial Cationic Peptides; D003902:Detergents; D008051:Lipid Bilayers; D008055:Lipids; D010446:Peptide Fragments; D010713:Phosphatidylcholines; D011328:Prions; C082632:prion protein (106-126); D002784:Cholesterol; C017251:1,2-oleoylphosphatidylcholine
keywords: Amyloid; Amyloid Oligomers; Atomic Force Microscopy; Cytotoxicity; Membrane Bilayer; Membrane Disruption; Peptides; Solid State NMR; TIRF