Specific recognition of biologically active amyloid-β oligomers by a new surface plasmon resonance-based immunoassay and an in vivo assay in Caenorhabditis elegans.
Soluble oligomers of the amyloid-β (Aβ) peptide play a key role in the pathogenesis of Alzheimer's disease, but their elusive nature makes their detection challenging. Here we describe a novel immunoassay based on surface plasmon resonance (SPR) that specifically recognizes biologically active Aβ oligomers. As a capturing agent, we immobilized on the sensor chip the monoclonal antibody 4G8, which targets a central hydrophobic region of Aβ. This SPR assay allows specific recognition of oligomeric intermediates that rapidly appear and disappear during the incubation of synthetic Aβ(1-42), discriminating them from monomers and higher order aggregates. The species recognized by SPR generate ionic currents in artificial lipid bilayers and inhibit the physiological pharyngeal contractions in Caenorhabditis elegans, a new method for testing the toxic potential of Aβ oligomers. With these assays we found that the formation of biologically relevant Aβ oligomers is inhibited by epigallocatechin gallate and increased by the A2V mutation, previously reported to induce early onset dementia. The SPR-based immunoassay provides new opportunities for detection of toxic Aβ oligomers in biological samples and could be adapted to study misfolding proteins in other neurodegenerative disorders.
Department of Molecular Biochemistry and Pharmacology, Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milan, Italy.
Matteo
M
Stravalaci
Antonio
A
Bastone
Marten
M
Beeg
Alfredo
A
Cagnotto
Laura
L
Colombo
Giuseppe
G
Di Fede
Fabrizio
F
Tagliavini
Laura
L
Cantù
Elena
E
Del Favero
Michele
M
Mazzanti
Roberto
R
Chiesa
Mario
M
Salmona
Luisa
L
Diomede
Marco
M
Gobbi
D000544:Alzheimer Disease / Q000235:genetics / Q000378:metabolism; D000682:Amyloid / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D058846:Antibodies, Monoclonal, Murine-Derived / Q000737:chemistry; D017173:Caenorhabditis elegans / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020349:Surface Plasmon Resonance
D000682:Amyloid; D016229:Amyloid beta-Peptides; D058846:Antibodies, Monoclonal, Murine-Derived; D029742:Caenorhabditis elegans Proteins