A novel crosslinking protocol stabilizes amyloid β oligomers capable of inducing Alzheimer's-associated pathologies

Amyloid beta oligomers (A beta Os) accumulate early in Alzheimer's disease (AD) and experimentally cause memory dysfunction and the major pathologies associated with AD, for example, tau abnormalities, synapse loss, oxidative damage, and cognitive dysfunction. In order to develop the most effective A beta O-targeting diagnostics and therapeutics, the A beta O structures contributing to AD-associated toxicity must be elucidated. Here, we investigate the structural properties and pathogenic relevance of A beta Os stabilized by the bifunctional crosslinker 1,5-difluoro-2,4-dinitrobenzene (DFDNB). We find that DFDNB stabilizes synthetic A beta in a soluble oligomeric conformation. With DFDNB, solutions of A beta that would otherwise convert to large aggregates instead yield solutions of stable A beta Os, predominantly in the 50-300 kDa range, that are maintained for at least 12 days at 37 degrees C. Structures were determined by biochemical and native top-down mass spectrometry analyses. Assayed in neuronal cultures and i.c.v.-injected mice, the DFDNB-stabilized A beta Os were found to induce tau hyperphosphorylation, inhibit choline acetyltransferase, and provoke neuroinflammation. Most interestingly, DFDNB crosslinking was found to stabilize an A beta O conformation particularly potent in inducing memory dysfunction in mice. Taken together, these data support the utility of DFDNB crosslinking as a tool for stabilizing pathogenic A beta Os in structure-function studies.