title: Amyloid Oligomers and Mature Fibrils Prepared from an Innocuous Protein Cause Diverging Cellular Death Mechanisms.
abstract: Despite significant advances, the molecular identity of the cytotoxic species populated during in vivo amyloid formation crucial for the understanding of neurodegenerative disorders is yet to be revealed. In this study lysozyme prefibrillar oligomers and fibrils in both mature and sonicated states have been isolated through an optimized ultrafiltration/ultracentrifugation method and characterized with various optical spectroscopic techniques, atomic force microscopy, and transmission electron microscopy. We examined their level and mode of toxicity on rat pheochromocytoma (PC12) cells in both differentiated and undifferentiated states. We find that oligomers and fibrils display cytotoxic capabilities toward cultured cells in vitro, with oligomers producing elevated levels of cellular injury toward undifferentiated PC12 cells (PC12(undiff)). Furthermore, dual flow cytometry staining experiments demonstrate that the oligomers and mature fibrils induce divergent cellular death pathways (apoptosis and secondary necrosis, respectively) in these PC12 cells. We have also shown that oligomers but not sonicated mature fibrils inhibit hippocampal long term potentiation, a form of synaptic plasticity implicated in learning and memory, in vivo. We conclude that our in vitro and in vivo findings confer a level of resistance toward amyloid fibrils, and that the PC 12-based comparative cytotoxicity assay can provide insights into toxicity differences between differently aggregated protein species.
authors.affiliation: Trinity Biomedical Sciences Institute (TBSI), School of Biochemistry and Immunology, Trinity College Dublin, the University of Dublin, Dublin 2, Ireland.
authors.forename: Níal P
authors.initials: NP
authors.lastname: Harte
authors.affiliation: Department of Pharmacology and Therapeutics, Trinity College Institute of Neuroscience (TCIN), Trinity College Dublin, the University of Dublin, Dublin 2, Ireland.
authors.forename: Igor
authors.initials: I
authors.lastname: Klyubin
authors.affiliation: School of Chemistry, Trinity College Dublin, the University of Dublin, Dublin 2, Ireland; Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, the University of Dublin, Dublin 2, Ireland.
authors.forename: Eoin K
authors.initials: EK
authors.lastname: McCarthy
authors.affiliation: Trinity Biomedical Sciences Institute (TBSI), School of Biochemistry and Immunology, Trinity College Dublin, the University of Dublin, Dublin 2, Ireland.
authors.forename: Soyoung
authors.initials: S
authors.lastname: Min
authors.affiliation: TCIN, Trinity College Dublin, the University of Dublin, Dublin 2, Ireland.
authors.forename: Sarah Ann
authors.initials: SA
authors.lastname: Garrahy
authors.affiliation: Trinity Biomedical Sciences Institute (TBSI), School of Biochemistry and Immunology, Trinity College Dublin, the University of Dublin, Dublin 2, Ireland.
authors.forename: Yongjing
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Trinity Biomedical Sciences Institute (TBSI), School of Biochemistry and Immunology, Trinity College Dublin, the University of Dublin, Dublin 2, Ireland; TCIN, Trinity College Dublin, the University of Dublin, Dublin 2, Ireland.
authors.forename: Gavin P
authors.initials: GP
authors.lastname: Davey
authors.affiliation: School of Chemistry, Trinity College Dublin, the University of Dublin, Dublin 2, Ireland; Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, the University of Dublin, Dublin 2, Ireland.
authors.forename: John J
authors.initials: JJ
authors.lastname: Boland
authors.affiliation: Department of Pharmacology and Therapeutics, Trinity College Institute of Neuroscience (TCIN), Trinity College Dublin, the University of Dublin, Dublin 2, Ireland.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rowan
authors.affiliation: Trinity Biomedical Sciences Institute (TBSI), School of Biochemistry and Immunology, Trinity College Dublin, the University of Dublin, Dublin 2, Ireland; Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, the University of Dublin, Dublin 2, Ireland. Electronic address: mok1@tcd.ie.
authors.forename: K Hun
authors.initials: KH
authors.lastname: Mok
mesh_terms: D000682:Amyloid / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001704:Biopolymers / Q000737:chemistry / Q000378:metabolism*; D016923:Cell Death; D016716:PC12 Cells; D051381:Rats
chemical_list: D000682:Amyloid; D001704:Biopolymers
keywords: amyloid; apoptosis; cell death; fibril; long term potentiation; neurodegenerative disease; oligomer; protein aggregation; protein misfolding