Inhibition of amyloidogenic Islet Amyloid Polypeptide aggregation with designed c

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DESCRIPTION (provided by applicant): The aggregation of the 37-amino acid polypeptide Islet Amyloid Polypeptide (IAPP, amylin), as either insoluble amyloid or as small oligomers, appears to play a direct role in the death of pancreatic ¿-islet cells in type 2 diabetes. While IAPP has been known to be the primary component of type 2 diabetes amyloid, the molecular interactions responsible for this aggregation are not fully understood. It is known that IAPP is found as extracellular deposits of amyloid in approximately 95% of patients afflicted with type 2 diabetes. IAPP has also been shown to be a toxic agent in vitro when added to human islet ¿-cells. While it remains unclear how self-assembly of IAPP leads to the development of disease, recent studies have suggested that the formation of lower order protein aggregates (two to ten self-assembled proteins) leads to cellular toxicity and ultimately to the progression of disease. Preventing the formation of these toxic oligomeric species may prevent, or slow, the progression of type 2 diabetes. We propose to use a fluorescent screen to identify peptides and small molecules that inhibit the self-assembly of amyloid-forming IAPP. In this screen, the gene for IAPP is genetically fused to the gene for enhanced green fluorescent protein (EGFP). When the IAPP-EGFP fusion protein is expressed in E. coli the natural propensity of IAPP to aggregate precludes EGFP from folding and fluorescing. However, in the presence of substances that prevent amyloid aggregation, the fused EGFP can fold properly and fluoresce green. We propose to screen designed combinatorial peptide libraries and small molecules to isolate and identify substances that inhibit amyloid formation and, therefore, show potential as therapeutic agents for preventing or slowing the progression of type 2 diabetes. PUBLIC HEALTH RELEVANCE: The aggregation of the small peptide Islet Amyloid Polypeptide (IAPP, amylin) appears to be directly related with loss of ¿-cells and the onset of type 2 diabetes. We propose to screen libraries of short peptides and small molecules to identify substances that inhibit amyloid formation. These experiments have the potential to discover new therapeutic agents for preventing, or slowing, the progression of type 2 diabetes.