Drug-Induced Reduction in 80Q Aggregates in a Dictyostelium discoideum Model of PolyQ Disease

Background/Objectives: Polyglutamine (polyQ) expansion induces protein misfolding, aggregation, and neurodegeneration; however, effective strategies for aggregate clearance remain limited. This study evaluated the effect of metformin, resveratrol, and curcumin on polyQ proteotoxicity using an engineered Dictyostelium discoideum model expressing 80Q repeats, and investigated their autophagy-related mechanism. Methods: In this study, 80Q-expressing Dictyostelium discoideum (D. discoideum) cells were treated with metformin, resveratrol, or curcumin. Cell viability and proliferation were assessed by growth curve and doubling-time analyses. Developmental assays examined restoration of multicellular morphology. PolyQ aggregation was analyzed using brightfield microscopy, fluorescence microscopy, Thioflavin T (ThT), and Congo Red assays. Quantitative real-time polymerase chain reaction (qRT-PCR) evaluated AMP-activated protein kinase (AMPK) and autophagy-related gene expression. Molecular docking and molecular dynamics (MD) simulations were performed to assess interactions between the compounds and AMPK. Results: All three compounds significantly improved viability and reduced doubling time in 80Q-expressing cells. Treated strains displayed improved developmental morphology and culmination compared to untreated controls. Thioflavin T (ThT) and Congo Red assays demonstrated a marked reduction in amyloid-like polyQ aggregates following treatment. Gene-expression analysis revealed the upregulation of AMP-activated protein kinase (AMPK) and core autophagy genes, indicating activation of an AMPK-linked pro-autophagy pathway involved in aggregate clearance. Computational studies further confirmed stable, energetically favorable interactions of metformin, resveratrol, and curcumin with AMPK. Conclusions: Metformin, resveratrol, and curcumin effectively reduce polyQ-associated proteotoxicity in D. discoideum and are associated with modulation of AMP-activated protein kinase (AMPK) signaling and autophagy-related pathways. These findings support the therapeutic potential of metabolic modulators against protein aggregation and establish D. discoideum as a valuable platform for screening autophagy-targeted interventions relevant to neurodegenerative diseases.