Modulation of α-Synuclein Fibrillation and Toxicity by 4-Phenylbutyric Acid

The protein misfolding and aggregation of α-synuclein (α-Syn) into neurotoxic amyloids underlies the pathogenesis of neurodegenerative diseases such as Parkinson's disease (PD). Emerging evidence suggests that 4-phenylbutyrate (PBA) may play a role as a potential chemical chaperone for targeting α-Syn aggregation, but its molecular mechanism remains largely unknown. Using in vitro assays, we demonstrate that PBA treatment alters the pattern of α-Syn aggregation, as evidenced by reduced formation of oligomeric species and its increased susceptibility to proteolytic cleavage under the influence of PBA. Proteinase K (PK) assays, surface plasmon resonance (SPR), Nile red assays, and cytotoxicity assays indicate that PBA interacts with the extensive hydrophobic contacts of α-Syn oligomers and significantly reduces α-Syn-amyloid-induced toxicity. Furthermore, using thioflavin T-based assays, we elucidated the kinetics of PBA-mediated modulation of α-Syn aggregation, highlighting its role in accelerating the formation of α-Syn amyloid fibrils. Molecular dynamics (MD) simulations suggest PBA's role in the destabilization of the C-terminus in α-Syn oligomers through multiple residue interactions. Collectively, our findings provide compelling evidence for the neuroprotective potential of PBA in targeting protein misfolding and aggregation in PD and suggest an avenue for disease-modifying interventions in neurodegenerative disorders.