An RNA-Focused DNA-Encoded Library Platform for Discovering Ligands of Pathogenic r(G₄C₂)^exp RNA

Disease-associated RNAs are increasingly recognized as promising therapeutic targets for small-molecule intervention. While DNA-encoded libraries (DELs) have long been established for protein ligand discovery, recent studies have demonstrated their feasibility for identifying RNA-binding small molecules. To further advance RNA-targeted ligand discovery, a diverse, solid-phase DEL enriched in privileged RNA-binding scaffolds was constructed and applied to identify ligands of r(G₄C₂)^exp, a toxic RNA repeat expansion implicated in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). DEL selection outcomes were analyzed through large-scale molecular docking integrated with physicochemical and structure-activity relationship (SAR) analyses. Correlations were observed between docking predictions and experimental enrichment trends, supporting lead identification. The lead compound was subsequently optimized based on rational design, resulting in analogues with enhanced binding affinity and bioactivity. These findings demonstrate that RNA ligand identification can be effectively achieved by combining DNA-encoded library technology with computational approaches for rational design and analysis and highlight a broadly adaptable platform for RNA-targeted small-molecule discovery.