title: Epigallocatechin-3-gallate and tetracycline differently affect ataxin-3 fibrillogenesis and reduce toxicity in spinocerebellar ataxia type 3 model.
abstract: The polyglutamine (polyQ)-containing protein ataxin-3 (AT3) triggers the neurodegenerative disease spinocerebellar ataxia type 3 (SCA3) when its polyQ tract is expanded beyond a critical length. This results in protein aggregation and generation of toxic oligomers and fibrils. Currently, no effective treatment is available for such and other polyQ diseases. Therefore, plenty of investigations are being carried on to assess the mechanism of action and the therapeutic potential of anti-amyloid agents. The polyphenol compound epigallocatechin-3-gallate (EGCG) and tetracycline have been shown to exert some effect in preventing fibrillogenesis of amyloidogenic proteins. Here, we have incubated an expanded AT3 variant with either compound to assess their effects on the aggregation pattern. The process was monitored by atomic force microscopy and Fourier transform infrared spectroscopy. Whereas in the absence of any treatment, AT3 gives rise to amyloid β-rich fibrils, whose hallmark is the typical glutamine side-chain hydrogen bonding, when incubated in the presence of EGCG it generated soluble, SDS-resistant aggregates, much poorer in β-sheets and devoid of any ordered side-chain hydrogen bonding. These are off-pathway species that persist until the latest incubation time and are virtually absent in the control sample. In contrast, tetracycline did not produce major alterations in the structural features of the aggregated species compared with the control, but substantially increased their solubility. Both compounds significantly reduced toxicity, as shown by the MTT assay in COS-7 cell line and in a transgenic Caenorhabditis elegans strain expressing in the nervous system an AT3 expanded variant in fusion with GFP.
authors.affiliation: Department of Biotechnologies and Biosciences.
authors.forename: Marcella
authors.initials: M
authors.lastname: Bonanomi
authors.affiliation: Department of Biotechnologies and Biosciences, Department of Physics G. Occhialini.
authors.forename: Antonino
authors.initials: A
authors.lastname: Natalello
authors.affiliation: Department of Biotechnologies and Biosciences.
authors.forename: Cristina
authors.initials: C
authors.lastname: Visentin
authors.affiliation: Department of Biotechnologies and Biosciences.
authors.forename: Valentina
authors.initials: V
authors.lastname: Pastori
authors.affiliation: Department of Physics, University of Genoa, 16146 Genoa, Italy.
authors.forename: Amanda
authors.initials: A
authors.lastname: Penco
authors.affiliation: Department of Biotechnologies and Biosciences.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Cornelli
authors.affiliation: Department of Biotechnologies and Biosciences.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Colombo
authors.affiliation: IFOM, The FIRC Institute of Molecular Oncology Foundation, 20139 Milan, Italy, Department of Health Sciences, University of Milan, 20122 Milan, Italy and.
authors.forename: Maria G
authors.initials: MG
authors.lastname: Malabarba
authors.affiliation: Department of Biotechnologies and Biosciences, Department of Physics G. Occhialini.
authors.forename: Silvia M
authors.initials: SM
authors.lastname: Doglia
authors.affiliation: Department of Physics, University of Genoa, 16146 Genoa, Italy, National Institute of Biostructures and Biosystems (INBB), 00136 Rome, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Relini
authors.affiliation: Department of Biotechnologies and Biosciences, Department of Statistics and Quantitative Methods, University of Milano-Bicocca, 20126 Milan, Italy, mariaelena.regonesi@unimib.it.
authors.forename: Maria E
authors.initials: ME
authors.lastname: Regonesi
authors.affiliation: Department of Biotechnologies and Biosciences.
authors.forename: Paolo
authors.initials: P
authors.lastname: Tortora
mesh_terms: D000682:Amyloid / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D000067699:Ataxin-3; D019556:COS Cells; D017173:Caenorhabditis elegans / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D004195:Disease Models, Animal; D015870:Gene Expression; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006860:Hydrogen Bonding; D017827:Machado-Joseph Disease / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D018625:Microscopy, Atomic Force; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D066329:Protein Aggregates / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D013752:Tetracycline / Q000494:pharmacology*
chemical_list: D000682:Amyloid; D029742:Caenorhabditis elegans Proteins; D009419:Nerve Tissue Proteins; D018696:Neuroprotective Agents; D066329:Protein Aggregates; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D002392:Catechin; C045651:epigallocatechin gallate; D000067699:Ataxin-3; C519526:atx-3 protein, C elegans; D013752:Tetracycline