Amyloid diseases involve conformational changes and aggregation of normally soluble peptides and proteins. As these proteins change begin to misfold and aggregate they pass through a toxic soluble oligomer stage and then they ultimately form insoluble fibrils. We have spent many years characterizing the early events in this progression, and have observed a common structure form among multiple amyloid-associated peptides and proteins despite distinct primary and tertiary structure. The structure we ?discovered?, which we call ?-sheet, while rare in normal proteins, has been observed experimentally, and short stretches of ?-strand are present in the Protein Data Bank. We embarked on an endeavor to design and evaluate small peptides with complementary structures, also ?-sheets, and their ability to inhibit amyloid formation in these systems. These de novo designed peptides inhibit the aggregation of multiple unrelated amyloid systems, indicating that we are targeting a generic structure. When immobilized, these designs also selectively bind the toxic oligomeric forms of these amyloid proteins over the monomers or fibrils. Here we propose to extend these studies by investigating whether ?-sheet forms during amyloidogenesis of Abeta variants associated with Alzheimer's disease. The effects of targeting the toxic oligomers with de novo ?-sheet designs will then be evaluated in vitro, in neuroblastoma cells, and in different, more biologically relevant systems.
We have discovered and characterized a novel structure, called ?-sheet, which we believe to be common among the soluble oligomeric forms of multiple amyloid peptides and proteins, including Abeta associated with Alzheimer's Disease. We have designed small peptides to be complementary to this structure, and they inhibit fibril formation via selective binding of the toxic oligomeric form of Abeta. Here we propose to investigate the structure of the amyloid species during the process of amyloidogenesis using different forms of Abeta, and explore the nature of the oligomers in CSF and in more biologically relevant model systems.
