Development of a Proteolytically Stable Retro-Inverso Peptide Inhibitor of β-Amyloid Oligomerization as a Potential Novel Treatment for Alzheimer’s Disease

Abstract

The formation of beta-amyloid (Abeta) deposits in the brain is likely to be a seminal step in the development of Alzheimer's disease. Recent studies support the hypothesis that Abeta soluble oligomers are toxic to cells and have potent effects on memory and learning. Inhibiting the early stages of Abeta aggregation could, therefore, provide a novel approach to treating the underlying cause of AD. We have designed a retro-inverso peptide (RI-OR2, H(2)N-r<--G<--k<--l<--v<--f<--f<--G<--r-Ac), based on a previously described inhibitor of Abeta oligomer formation (OR2, H(2)N-R-G-K-L-V-F-F-G-R-NH(2)). Unlike OR2, RI-OR2 was highly stable to proteolysis and completely resisted breakdown in human plasma and brain extracts. RI-OR2 blocked the formation of Abeta oligomers and fibrils from extensively deseeded preparations of Abeta(1-40) and Abeta(1-42), as assessed by thioflavin T binding, an immunoassay method for Abeta oligomers, SDS-PAGE separation of stable oligomers, and atomic force microscopy, and was more effective against Abeta(1-42) than Abeta(1-40). In surface plasmon resonance experiments, RI-OR2 was shown to bind to immobilized Abeta(1-42) monomers and fibrils, with an apparent K(d) of 9-12 muM, and also acted as an inhibitor of Abeta(1-42) fibril extension. In two different cell toxicity assays, RI-OR2 significantly reversed the toxicity of Abeta(1-42) toward cultured SH-SY5Y neuroblastoma cells. Thus, RI-OR2 represents a strong candidate for further development as a novel treatment for Alzheimer's disease.

Metabolic study of Alzheimer’s disease using mutant C. elegans

“…As glucose enrichment was found to induce intracellular glucose levels in C. elegans ( Figure S6.1, [539]), it is possible that glucose addition may affect Aβ oligomerization in transgenic worms as well. It has been widely accepted that Aβ monomers are non-toxic, and the accumulation of Aβ oligomers is responsible for Aβ-mediated neurotoxicity as early cognitive decline appears before the Aβ plaque formation in the patients with AD [14][15][16][17][18][19][20][21][22][23][24]. In our study, glucose gradually induced Aβ oligomerization accompanied by decrease in Aβ monomers.…”

“…Aβ monomers are considered non-toxic to neurons whereas small soluble Aβ oligomers are likely to be responsible for Aβ-mediated neurotoxicity [13]. This is presumed because an early cognitive decline appears before the deposition of oligomers to form plaques in patients with AD [14][15][16][17][18][19][20]. Furthermore, drug screening studies demonstrate that reduction in Aβ oligomers is beneficial even if the level of monomers increase highlighting the key role of Aβ oligomers in disease progression [21][22][23][24].…”

A Peptide–Glycolipid Interaction Probed by Retroinverso Peptide Analogues

“…Based on these structural features, retroinverso peptides can conveniently provide topological analogues of any short peptide sequence when the molecular recognition event between the peptide and its receptor involves only the side chain interactions. [16][17][18][19][20] We are interested in exploring the utility of retroinverso Dpeptide analogues as novel glycolipid-binding probes based on their synthetic accessibility, their facile synthetic modification, and their potential resistance toward proteases, which would be useful in the study of glycolipids in live cell settings. Retroinverso peptides also provide a convenient way to quickly test whether a specific interaction of the peptide backbone or its polarity are critical in glycolipid binding.…”

Validation and Characterization of a Novel Peptide That Binds Monomeric and Aggregated β-Amyloid and Inhibits the Formation of Neurotoxic Oligomers

“…26. Either 15M S.A. peptide, or A␤42 monomer/aggregates, were immobilized on separate CM5 sensorchips (GE Healthcare).…”