title: Toxic effects of amyloid fibrils on cell membranes: the importance of ganglioside GM1.
abstract: The interaction of amyloid aggregates with the cell plasma membrane is currently considered among the basic mechanisms of neuronal dysfunction in amyloid neurodegeneration. We used amyloid oligomers and fibrils grown from the yeast prion Sup35p, responsible for the specific prion trait [PSI(+)], to investigate how membrane lipids modulate fibril interaction with the membranes of cultured H-END cells and cytotoxicity. Sup35p shares no homology with endogenous mammalian polypeptide chains. Thus, the generic toxicity of amyloids and the molecular events underlying cell degeneration can be investigated without interference with analogous polypeptides encoded by the cell genome. Sup35 fibrils bound to the cell membrane without increasing its permeability to Ca(2+). Fibril binding resulted in structural reorganization and aggregation of membrane rafts, with GM1 clustering and alteration of its mobility. Sup35 fibril binding was affected by GM1 or its sialic acid moiety, but not by cholesterol membrane content, with complete inhibition after treatment with fumonisin B1 or neuraminidase. Finally, cell impairment resulted from caspase-8 activation after Fas receptor translocation on fibril binding to the plasma membrane. Our observations suggest that amyloid fibrils induce abnormal accumulation and overstabilization of raft domains in the cell membrane and provide a reasonable, although not unique, mechanistic and molecular explanation for fibril toxicity.
authors.affiliation: Department of Biochemical Sciences, University of Florence, Florence, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Bucciantini
authors.forename: Daniele
authors.initials: D
authors.lastname: Nosi
authors.forename: Mario
authors.initials: M
authors.lastname: Forzan
authors.forename: Edda
authors.initials: E
authors.lastname: Russo
authors.forename: Martino
authors.initials: M
authors.lastname: Calamai
authors.forename: Laura
authors.initials: L
authors.lastname: Pieri
authors.forename: Lucia
authors.initials: L
authors.lastname: Formigli
authors.forename: Franco
authors.initials: F
authors.lastname: Quercioli
authors.forename: Silvia
authors.initials: S
authors.lastname: Soria
authors.forename: Francesco
authors.initials: F
authors.lastname: Pavone
authors.forename: Jimmy
authors.initials: J
authors.lastname: Savistchenko
authors.forename: Ronald
authors.initials: R
authors.lastname: Melki
authors.forename: Massimo
authors.initials: M
authors.lastname: Stefani
mesh_terms: D000682:Amyloid / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer; D005677:G(M1) Ganglioside / Q000378:metabolism*; D007150:Immunohistochemistry; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D010454:Peptide Termination Factors / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity; D055503:Protein Multimerization; D053218:Receptors, Death Domain / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity
chemical_list: D000682:Amyloid; D010454:Peptide Termination Factors; D053218:Receptors, Death Domain; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D005677:G(M1) Ganglioside; D019158:N-Acetylneuraminic Acid