Cell-Based Screen Using Amyloid Mimic β23 Expression Identifies Peucedanocoumarin III as a Novel Inhibitor of α-Synuclein and Huntingtin Aggregates

Aggregates of disease-causing proteins dysregulate cellular functions, thereby causing neuronal cell loss in diverse neurodegenerative diseases. Although many in vitro or in vivo studies of protein aggregate inhibitors have been performed, a therapeutic strategy to control aggregate toxicity has not been earnestly pursued, partly due to the limitations of available aggregate models. In this study, we established a tetracycline (Tet)-inducible nuclear aggregate (beta 23) expression model to screen potential lead compounds inhibiting beta 23-induced toxicity. High-throughput screening identified several natural compounds as nuclear beta 23 inhibitors, including peucedanocoumarin III (PCIII). Interestingly, PCIII accelerates disaggregation and proteasomal clearance of both nuclear and cytosolic beta 23 aggregates and protects SH-SY5Y cells from toxicity induced by beta 23 expression. Of translational relevance, PCIII disassembled fibrils and enhanced clearance of cytosolic and nuclear protein aggregates in cellular models of huntingtin and alpha-synuclein aggregation. Moreover, cellular toxicity was diminished with PCIII treatment for polyglutamine (PolyQ)-huntingtin expression and alpha-synuclein expression in conjunction with 6-hydroxydopamine (6-OHDA) treatment. Importantly, PCIII not only inhibited alpha-synuclein aggregation but also disaggregated preformed alpha-synuclein fibrils in vitro. Taken together, our results suggest that a Tet-Off beta 23 cell model could serve as a robust platform for screening effective lead compounds inhibiting nuclear or cytosolic protein aggregates. Brain-permeable PCIII or its derivatives could be beneficial for eliminating established protein aggregates.