Abstract
AbstractThe aggregation of Amyloid-β (Aβ) is associated with the onset of Alzheimer’s Disease (AD) and involves a complex kinetic pathway as monomers self-assemble into fibrils. A central feature of amyloid fibrils is the existence of multiple structural polymorphs, which complicates the development of disease-relevant structure-function relationships. Developing these relationships requires new methods to control fibril structure. In this work, we demonstrate that mesoporous silicas (SBA-15) functionalized with hydrophobic (SBA-PFDTS) and hydrophilic groups (SBA-PEG) direct the aggregation kinetics and resulting structure of Aβ1-40 fibrils. The hydrophilic SBA-PEG had little effect on amyloid kinetics while as-synthesized and hydrophobic SBA-PFDTS accelerated aggregation kinetics. Subsequently, we quantified the relative population of fibril structures formed in the presence of each material using electron microscopy. Fibrils formed from Aβ1-40 exposed to SBA-PEG were structurally similar to control fibrils. In contrast, Aβ1-40 incubated with SBA-15 or SBA-PFDTS formed fibrils with shorter cross-over distances that were more structurally representative of fibrils found in AD patient-derived samples. Overall, these results suggest that mesoporous silicas and other exogenous materials are promising scaffolds for the de novo production of specific fibril polymorphs of Aβ1-40 and other amyloidogenic proteins.Significance StatementA major challenge in understanding the progression of Alzheimer’s Disease lies in the various fibril structures, or polymorphs, adopted by Amyloid-β (Aβ). Heterogenous fibril populations may be responsible for different disease phenotypes and growing evidence suggests that Aβ fibrils formed in vitro are structurally distinct from patient-derived fibrils. To help bridge this gap, we used surface-functionalized mesoporous silicas to influence the formation of Aβ1-40 fibrils and evaluated the distribution of resulting fibril polymorphs using electron microscopy (EM). We found that silicas modified with hydrophobic surfaces resulted in fibril populations with shorter cross-over distances that are more representative of Aβ fibrils observed ex vivo. Overall, our results indicate that mesoporous silicas may be leveraged for the production of specific Aβ polymorphs.
Publisher
Cold Spring Harbor Laboratory