title: Clusterin Binds to Aβ1-42 Oligomers with High Affinity and Interferes with Peptide Aggregation by Inhibiting Primary and Secondary Nucleation.
abstract: The aggregation of amyloid β protein (Aβ) is a fundamental pathogenic mechanism leading to the neuronal damage present in Alzheimer disease, and soluble Aβ oligomers are thought to be a major toxic culprit. Thus, better knowledge and specific targeting of the pathways that lead to these noxious species may result in valuable therapeutic strategies. We characterized some effects of the molecular chaperone clusterin, providing new and more detailed evidence of its potential neuroprotective effects. Using a classical thioflavin T assay, we observed a dose-dependent inhibition of the aggregation process. The global analysis of time courses under different conditions demonstrated that clusterin has no effect on the elongation rate but mainly interferes with the nucleation processes (both primary and secondary), reducing the number of nuclei available for further fibril growth. Then, using a recently developed immunoassay based on surface plasmon resonance, we obtained direct evidence of a high-affinity (KD= 1 nm) interaction of clusterin with biologically relevant Aβ1-42oligomers, selectively captured on the sensor chip. Moreover, with the same technology, we observed that substoichiometric concentrations of clusterin prevent oligomer interaction with the antibody 4G8, suggesting that the chaperone shields hydrophobic residues exposed on the oligomeric assemblies. Finally, we found that preincubation with clusterin antagonizes the toxic effects of Aβ1-42oligomers, as evaluated in a recently developedin vivomodel inCaenorhabditis elegans.These data substantiate the interaction of clusterin with biologically active regions exposed on nuclei/oligomers of Aβ1-42, providing a molecular basis for the neuroprotective effects of the chaperone.
authors.affiliation: From the Department of Molecular Biochemistry and Pharmacology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milan, Italy.
authors.forename: Marten
authors.initials: M
authors.lastname: Beeg
authors.affiliation: From the Department of Molecular Biochemistry and Pharmacology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milan, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Stravalaci
authors.affiliation: From the Department of Molecular Biochemistry and Pharmacology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milan, Italy.
authors.forename: Margherita
authors.initials: M
authors.lastname: Romeo
authors.affiliation: From the Department of Molecular Biochemistry and Pharmacology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milan, Italy.
authors.forename: Arianna Dorotea
authors.initials: AD
authors.lastname: Carrá
authors.affiliation: From the Department of Molecular Biochemistry and Pharmacology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milan, Italy.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Cagnotto
authors.affiliation: From the Department of Molecular Biochemistry and Pharmacology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milan, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Rossi
authors.affiliation: From the Department of Molecular Biochemistry and Pharmacology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milan, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Diomede
authors.affiliation: From the Department of Molecular Biochemistry and Pharmacology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milan, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Salmona
authors.affiliation: From the Department of Molecular Biochemistry and Pharmacology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milan, Italy marco.gobbi@marionegri.it.
authors.forename: Marco
authors.identifier: http://orcid.org/0000-0003-1014-6225
authors.initials: M
authors.lastname: Gobbi
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors* / Q000138:chemical synthesis / Q000633:toxicity; D000818:Animals; D001681:Biological Assay; D017173:Caenorhabditis elegans / Q000187:drug effects* / Q000502:physiology; D051152:Clusterin / Q000302:isolation & purification / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D007814:Larva / Q000187:drug effects / Q000502:physiology; D018696:Neuroprotective Agents / Q000302:isolation & purification / Q000494:pharmacology*; D010446:Peptide Fragments / Q000037:antagonists & inhibitors* / Q000138:chemical synthesis / Q000633:toxicity; D010614:Pharynx / Q000187:drug effects* / Q000502:physiology; D066329:Protein Aggregates / Q000187:drug effects; D066263:Protein Aggregation, Pathological / Q000473:pathology / Q000517:prevention & control*; D011485:Protein Binding
chemical_list: D016229:Amyloid beta-Peptides; C495242:CLU protein, human; D051152:Clusterin; D018696:Neuroprotective Agents; D010446:Peptide Fragments; D066329:Protein Aggregates; C075222:amyloid beta-protein (1-42)
keywords: Alzheimer disease; Caenorhabditis elegans; amyloid β (Aβ); chaperone; clusterin; kinetics; kinetics of fibril formation; surface plasmon resonance (SPR)