title: Effect of molecular chaperones on aberrant protein oligomers in vitro: super-versus sub-stoichiometric chaperone concentrations.
abstract: Living systems protect themselves from aberrant proteins by a network of chaperones. We have tested in vitro the effects of different concentrations, ranging from 0 to 16 μm, of two molecular chaperones, namely αB-crystallin and clusterin, and an engineered monomeric variant of transthyretin (M-TTR), on the morphology and cytotoxicity of preformed toxic oligomers of HypF-N, which represent a useful model of misfolded protein aggregates. Using atomic force microscopy imaging and static light scattering analysis, all were found to bind HypF-N oligomers and increase the size of the aggregates, to an extent that correlates with chaperone concentration. SDS-PAGE profiles have shown that the large aggregates were predominantly composed of the HypF-N protein. ANS fluorescence measurements show that the chaperone-induced clustering of HypF-N oligomers does not change the overall solvent exposure of hydrophobic residues on the surface of the oligomers. αB-crystallin, clusterin and M-TTR can diminish the cytotoxic effects of the HypF-N oligomers at all chaperone concentration, as demonstrated by MTT reduction and Ca2+ influx measurements. The observation that the protective effect is primarily at all concentrations of chaperones, both when the increase in HypF-N aggregate size is minimal and large, emphasizes the efficiency and versatility of these protein molecules.
authors.forename: Sara
authors.initials: S
authors.lastname: Cappelli
authors.forename: Amanda
authors.initials: A
authors.lastname: Penco
authors.forename: Benedetta
authors.initials: B
authors.lastname: Mannini
authors.forename: Roberta
authors.initials: R
authors.lastname: Cascella
authors.forename: Mark R
authors.initials: MR
authors.lastname: Wilson
authors.forename: Heath
authors.initials: H
authors.lastname: Ecroyd
authors.forename: Xinyi
authors.initials: X
authors.lastname: Li
authors.forename: Joel N
authors.initials: JN
authors.lastname: Buxbaum
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Dobson
authors.forename: Cristina
authors.initials: C
authors.lastname: Cecchi
authors.forename: Annalisa
authors.initials: A
authors.lastname: Relini
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Chiti
mesh_terms: D000818:Animals; D019878:Carboxyl and Carbamoyl Transferases / Q000737:chemistry* / Q000378:metabolism; D045744:Cell Line, Tumor; D051152:Clusterin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D051379:Mice; D011228:Prealbumin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D066329:Protein Aggregates; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D038203:alpha-Crystallin B Chain / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D051152:Clusterin; D029968:Escherichia coli Proteins; D011228:Prealbumin; D066329:Protein Aggregates; D011994:Recombinant Proteins; D038203:alpha-Crystallin B Chain; D019878:Carboxyl and Carbamoyl Transferases; C504838:hypF protein, E coli