α-synuclein aggregation inhibitor (IOCB Tech)

Becker muscular dystrophy (BMD) is caused by in-frame mutations in dystrophin gene, leading to progressive muscle weakness, and cardiac and respiratory complications. Currently, there is no cure. We have recently identified the importance of poly-ubiquitination in regulating dystrophin stability through the binding of lncRNA H19 to the dystrophin C-terminal zinc-finger domain (ZNF), inhibiting TRIM63-mediated poly-ubiquitination. We also demonstrated that BMD mutations lead to conformational changes in ZNF domain, reduced lncRNA H19 binding and increased dystrophin ubiquitination. Here we used BMD iPSCs to investigate the in vitro myogenic potential of BMD myogenic cells, as well as in vitro and in vivo studies to evaluate the therapeutic efficacy of three candidate molecules targeting dystrophin ubiquitination pathway. In vitro assays indicated significant deficiencies in myogenic cell differentiation of BMD iPSCs, including reduced proliferation, cell-cycle arrest, increased apoptosis, senescence, and membrane damage, and impaired myotube formation. In vivo engraftment demonstrated significant improvement in BMD iPSC myogenic cell survival and dystrophin expression in the animals treated with two molecules: a TRIM63 inhibitor and an α-synuclein aggregation inhibitor. These findings provide promising evidence for the potential therapeutic efficacy of these ubiquitination pathway inhibitors to improve muscle progenitor cell survival and dystrophin expression in BMD patients.

Developing α-synuclein aggregation inhibitors is challenging because its aggregation process involves several microscopic steps and heterogeneous intermediates. Previously, we identified a SUMO1-derived peptide, SUMO1(15-55), that exhibits tight binding to monomeric α-synuclein via SUMO-SUMO-interacting motif (SIM) interactions, and effectively blocks the initiation of aggregation and formation of toxic aggregates in vitro. In cellular and Drosophila models, SUMO1(15-55) was efficacious in protecting neuronal cells from α-synuclein-induced neurotoxicity and neuronal degeneration. Given the demonstrated ability of SUMO1(15-55) to sequester α-synuclein monomers thereby blocking oligomer formation, we sought to evaluate whether it could be equally effective against the aggregation-prone familial mutant α-synuclein-A53T. Herein, we show that SUMO1(15-55) selectively binds to monomeric α-synuclein-A53T, inhibits primary nucleation, and prevents the formation of structured protofibrils in vitro, thereby protecting neuronal cells from protofibril-induced cell death. We further demonstrate that larval feeding of a designed His₁₀-SUMO1(15-55) that exhibits enhanced sub-stoichiometric suppression of α-synuclein-A53T aggregation in vitro can ameliorate Parkinson's disease (PD)-related symptoms in α-synuclein-A53T transgenic Drosophila models, while its rAAV-mediated gene delivery can relieve the PD-related histological and behavioral deficiencies in an rAAV-α-synuclein-A53T mouse PD model. Our findings suggest that gene delivery of His₁₀-SUMO1(15-55) may serve as a clinical therapy for a spectrum of α-synuclein-aggregation associated synucleinopathies.