Article

Small Molecule Microarrays Enable the Discovery of Compounds That Bind the Alzheimer’s Aβ Peptide and Reduce its Cytotoxicity

Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
Journal of the American Chemical Society (Impact Factor: 11.44). 11/2010; 132(47):17015-22. DOI: 10.1021/ja107552s
Source: PubMed

ABSTRACT The amyloid-β (Aβ) aggregation pathway is a key target in efforts to discover therapeutics that prevent or delay the onset of Alzheimer's disease. Efforts at rational drug design, however, are hampered by uncertainties about the precise nature of the toxic aggregate. In contrast, high-throughput screening of compound libraries does not require a detailed understanding of the structure of the toxic species, and can provide an unbiased method for the discovery of small molecules that may lead to effective therapeutics. Here, we show that small molecule microarrays (SMMs) represent a particularly promising tool for identifying compounds that bind the Aβ peptide. Microarray slides with thousands of compounds immobilized on their surface were screened for binding to fluorescently labeled Aβ. Seventy-nine compounds were identified by the SMM screen, and then assayed for their ability to inhibit the Aβ-induced killing of PC12 cells. Further experiments focused on exploring the mechanism of rescue for one of these compounds: Electron microscopy and Congo red binding showed that the compound enhances fibril formation, and suggest that it may rescue cells by accelerating Aβ aggregation past an early toxic oligomer. These findings demonstrate that the SMM screen for binding to Aβ is effective at identifying compounds that reduce Aβ toxicity, and can reveal potential therapeutic leads without the biases inherent in methods that focus on inhibitors of aggregation.

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    • "X-ray crystallography has also been employed but has the distinct disadvantage of not being able to monitor binding in aqueous solution because samples need to be crystallized [2,33–35]. Several array-based methods have been reported in the literature during recent years, immobilizing either a fragment of the parent peptide [36] [37] or a small molecule ligand [38] [39] on a surface and then detecting the resulting binding that occurs. Although innovative, these approaches require the use of shortened AA fragments of the full-length target protein and, thus, do not allow for assessment of ligand binding sites using the full 3D protein/peptide structure. "
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