Convergent biochemical and genetic evidence suggests that the formation of β-amyloid (Aβ) deposits in the brain is an important and, probably, seminal step in the development of Alzheimer's disease (AD). Recent studies support the hypothesis that Aβ soluble oligomers are the pathogenic species that prompt the disease. Inhibiting Aβ self-oligomerization could, therefore, provide a novel approach to treating the underlying cause of AD. Here, we designed potential peptide-based aggregation inhibitors containing Aβ amino acid sequences (KLVFF) from part of the binding region responsible for Aβ self-association (residues 16-20), with RG-/-GR residues added at their N- and C-terminal ends to aid solubility. Two such peptides (RGKLVFFGR, named OR1, and RGKLVFFGR-NH2, named OR2) were effective inhibitors of Aβ fibril formation, but only one of these peptides (OR2) inhibited Aβ oligomer formation. Interestingly, this same OR2 peptide was the only effective inhibitor of Aβ toxicity toward human neuroblastoma SH-SY5Y cells. Our data support the idea that Aβ oligomers are responsible for the cytotoxic effects of Aβ and identify a potential peptide inhibitor for further development as a novel therapy for AD.
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