Development of an RNA Aptamer as a Therapeutic Agent for Synucleinopathies

The aggregation of α-synuclein (αSyn), a 140-mer protein, has been implicated in the pathogenesis of Parkinson’s disease, multiple system atrophy, and dementia with Lewy bodies. KTKEGV repeats (KR) of αSyn are key mediators of prion-like propagation and neurodegeneration. Despite the availability of symptomatic treatments, no current therapy effectively delays disease progression. Here we report a 77-nucleotide (nt) RNA aptamer (1R6) with potent affinity and selectivity for αSyn1-95 ( K _D = 18 nM) through in vitro selection. 1R6 significantly inhibited αSyn oligomerization and β-sheet-rich fibril assembly and promoted disaggregation of preformed fibrils. Additionally, 1R6 suppressed αSyn seeding, as determined by FRET-based cellular biosensor cell assay. Cellular studies revealed that 1R6 cotransfection completely prevented αSyn-induced cytotoxicity. To assess the protective effects of 1R6 in vivo , we used a Drosophila melanogaster model expressing human αSyn in neurons. Flies fed with 1R6 showed improved locomotor defects, reduced photoreceptor degeneration, and decreased αSyn levels in the head. Structural characterization through ¹ H- ¹⁵ N heteronuclear multiple quantum correlation nuclear magnetic resonance experiments demonstrated that 1R6 targets KR motifs, a finding further supported by in silico simulations. Our findings indicate that RNA aptamers, such as 1R6, may represent promising therapeutic candidates for synucleinopathies, thus opening new avenues in the treatment of these diseases.