α-synuclein aggregation inhibitor (IOCB Tech)

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.

α-Synuclein aggregation under pathological conditions is one of the causes of related neurodegenerative diseases. PROTACs (proteolysis targeting chimeras) are bifunctional small molecules that induce a post-translational erasure of proteins via the ubiquitination of target proteins by E3 ubiquitin ligase and subsequent proteasomal degradation. However, few research studies have been conducted for targeted protein degradation of α-synuclein aggregates. In this article, we have designed and synthesized a series of small-molecule degraders 1-9 based on a known α-synuclein aggregation inhibitor sery384. In silico docking studies of sery384 with α-synuclein aggregates were accomplished to ensure that the compounds bound to α-synuclein aggregates specifically. The protein level of α-synuclein aggregates was determined to evaluate the degradation efficiency of PROTAC molecules on α-synuclein aggregates in vitro. The results show that compound 5 had the most significant degradation effect, with DC₅₀ of 5.049 μM, and could induce the degradation of α-synuclein aggregates in a time- and dose-dependent manner in vitro. Furthermore, compound 5 could inhibit the elevation of the ROS level caused by overexpression and aggregation of α-synuclein and protect H293T cells from α-synuclein toxicity. Conclusively, our results provide a new class of small-molecule degraders and an experimental basis for the treatment of α-synuclein related neurodegenerative diseases.