Date of Graduation
Eberly College of Arts and Sciences
As protein aggregation is the defining hallmark of all amyloid diseases, a common therapeutic strategy is to develop molecules that inhibit aggregation. However, this approach has yielded limited success. Many amyloid proteins directly interact with lipid membranes. These interactions promote distinct aggregation pathways and often result in membrane damage leading to toxicity. As a result, directly targeting the ability of amyloids to bind lipid membranes represents a novel therapeutic strategy. As a proof of principle, the interaction between lipid membranes and mutant huntingtin protein (htt) aggregates was used to test this strategy. Mutant htt containing an expanded polygulatmine (polyQ) domain causes Huntington’s disease (HD). Using a colorimetric lipid binding assay over 1200 compounds were screened for their ability to block htt/lipid binding. The screen was set up to only identify compounds that directly interacted with htt, not the lipid membrane. Three compounds were identified having the ability to inhibit htt/lipid interaction, Ro-90-7501 (Ro), benzamil hydrochloride (ben) and ruthenium red. As these compounds directly interact with htt, ThT and AFM assays were performed to assess their impact on aggregation. Ro and ben did not inhibit fibril formation; however, oligomer precursors were significantly smaller when exposed to Benzamil. Molecular dynamic simulations (MD) revealed that the two compounds have unique mechanisms of interaction with htt aggregates. Unlike Ro and ben, ruthenium red altered htt aggregation and inhibit fibrilization. Having established that the compound prevented htt from binding membranes, a C. elegans model of HD was used to determine if this strategy could alleviate phenotype. Despite have a minimal impact on punctate formation, all three compounds reduced a thrashing deficit in animals caused by mutant htt expression, suggesting that this strategy reduces htt toxicity.
Siriwardhana, Chathuranga, "Lipid binding properties of huntingtin as a novel therapeutic target" (2023). Graduate Theses, Dissertations, and Problem Reports. 11891.