Cell-Permeable, Small-Molecule Activators of the Insulin-Degrading Enzyme.
ABSTRACT The insulin-degrading enzyme (IDE) cleaves numerous small peptides, including biologically active hormones and disease-related peptides. The propensity of IDE to degrade neurotoxic A peptides marks IDE as a potential therapeutic target for Alzheimer disease. Using a synthetic reporter based on the yeast a-factor mating pheromone precursor, which is cleaved by multiple IDE orthologs, we identified seven small molecules that stimulate rat IDE activity in vitro. Half-maximal activation of IDE by the compounds is observed in vitro in the range of 43 to 198 M. All compounds decrease the K(m) of IDE. Four compounds activate IDE in the presence of the competing substrate insulin, which disproportionately inhibits IDE activity. Two compounds stimulate rat IDE activity in a cell-based assay, indicating that they are cell permeable. The compounds demonstrate specificity for rat IDE since they do not enhance the activities of IDE orthologs, including human IDE, and they appear specific for a-factorbased reporters since they do not enhance rat IDE-mediated cleavage of A-based reporters. Our results suggest that IDE activators function in the context of specific enzyme-substrate pairs, indicating that the choice of substrate must be considered in addition to target validation in IDE activator screens.
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ABSTRACT: Insulin degrading enzyme (IDE) is a highly conserved zinc metalloprotease that is involved in the clearance of various physiologically peptides like amyloid-beta and insulin. This enzyme has been involved in the physiopathology of diabetes and Alzheimer's disease. We describe here a series of small molecules discovered by screening. Co-crystallization of the compounds with IDE revealed a binding both at the permanent exosite and at the discontinuous, conformational catalytic site. Preliminary structure-activity relationships are described. Selective inhibition of amyloid-beta degradation over insulin hydrolysis was possible. Neuroblastoma cells treated with the optimized compound display a dose-dependent increase in amyloid-beta levels.European Journal of Medicinal Chemistry 04/2014; 79C:184-193. · 3.43 Impact Factor