title: Different ataxin-3 amyloid aggregates induce intracellular Ca(2+) deregulation by different mechanisms in cerebellar granule cells.
abstract: This work aims at elucidating the relation between morphological and physicochemical properties of different ataxin-3 (ATX3) aggregates and their cytotoxicity. We investigated a non-pathological ATX3 form (ATX3Q24), a pathological expanded form (ATX3Q55), and an ATX3 variant truncated at residue 291 lacking the polyQ expansion (ATX3/291Δ). Solubility, morphology and hydrophobic exposure of oligomeric aggregates were characterized. Then we monitored the changes in the intracellular Ca(2+) levels and the abnormal Ca(2+) signaling resulting from aggregate interaction with cultured rat cerebellar granule cells. ATX3Q55, ATX3/291Δ and, to a lesser extent, ATX3Q24 oligomers displayed similar morphological and physicochemical features and induced qualitatively comparable time-dependent intracellular Ca(2+) responses. However, only the pre-fibrillar aggregates of expanded ATX3 (the only variant which forms bundles of mature fibrils) triggered a characteristic Ca(2+) response at a later stage that correlated with a larger hydrophobic exposure relative to the two other variants. Cell interaction with early oligomers involved glutamatergic receptors, voltage-gated channels and monosialotetrahexosylganglioside (GM1)-rich membrane domains, whereas cell interaction with more aged ATX3Q55 pre-fibrillar aggregates resulted in membrane disassembly by a mechanism involving only GM1-rich areas. Exposure to ATX3Q55 and ATX3/291Δ aggregates resulted in cell apoptosis, while ATX3Q24 was substantially innocuous. Our findings provide insight into the mechanisms of ATX3 aggregation, aggregate cytotoxicity and calcium level modifications in exposed cerebellar cells.
authors.affiliation: Department of Physics, University of Genoa, Genoa, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Pellistri
authors.affiliation: Department of Biomedical, Experimental and Clinical Sciences, University of Florence, Florence, Italy; Research Centre on the Molecular Basis of Neurodegeneration, Florence, Italy. Electronic address: monica.bucciantini@unifi.it.
authors.forename: Monica
authors.initials: M
authors.lastname: Bucciantini
authors.affiliation: Department of Biotechnologies and Biosciences, University of Milano-Bicocca, Milan, Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Invernizzi
authors.affiliation: Department of Physics, University of Genoa, Genoa, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Gatta
authors.affiliation: Department of Physics, University of Genoa, Genoa, Italy.
authors.forename: Amanda
authors.initials: A
authors.lastname: Penco
authors.affiliation: Department of Biotechnologies and Biosciences, University of Milano-Bicocca, Milan, Italy.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Frana
authors.affiliation: Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Nosi
authors.affiliation: Department of Physics, University of Genoa, Genoa, Italy; Research Centre on the Molecular Basis of Neurodegeneration, Florence, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Relini
authors.affiliation: Department of Biotechnologies and Biosciences, University of Milano-Bicocca, Milan, Italy.
authors.forename: Maria Elena
authors.initials: ME
authors.lastname: Regonesi
authors.affiliation: Department of Physics, University of Genoa, Genoa, Italy; Research Centre on the Molecular Basis of Neurodegeneration, Florence, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Gliozzi
authors.affiliation: Department of Biotechnologies and Biosciences, University of Milano-Bicocca, Milan, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Tortora
authors.affiliation: Department of Physics, University of Genoa, Genoa, Italy; Research Centre on the Molecular Basis of Neurodegeneration, Florence, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Robello
authors.affiliation: Department of Biomedical, Experimental and Clinical Sciences, University of Florence, Florence, Italy; Research Centre on the Molecular Basis of Neurodegeneration, Florence, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Stefani
mesh_terms: D000682:Amyloid / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002531:Cerebellum / Q000166:cytology*; D005677:G(M1) Ganglioside / Q000494:pharmacology; D042541:Intracellular Space / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D009419:Nerve Tissue Proteins / Q000378:metabolism* / Q000633:toxicity*; D011485:Protein Binding / Q000187:drug effects; D020836:Protein Structure, Quaternary; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013997:Time Factors
chemical_list: D000682:Amyloid; D015220:Calcium Channels; D009419:Nerve Tissue Proteins; D018091:Receptors, AMPA; D005677:G(M1) Ganglioside; D002118:Calcium
keywords: 2-amino-5-phosphonopentanoic acid; 8-anilino-1-naphthalenesulfonic acid; AMPA-R; ANS; APV; Amyloid aggregate; Ataxin-3; BSA; CGNs; CNQX; Fibril toxicity; GM1; Intracellular Ca(2+) level; JD; N-methyl-d-aspartate receptor; N-terminal Josephin domain; NMDA-R; Oligomer toxicity; SBMA; SCA3; ThT; Thioflavin T; VGCCs; bovine serum albumin; cyano-nitroquinoxaline-dione; monosialotetrahexosylganglioside; rat cerebellar granule neurons; spinobulbar muscular atrophy; spinocerebellar ataxia type 3; voltage-gated calcium channels; α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor