Circular RNA Translation Modulation via Small Ligand-Mediated Protein Stabilization

Circular RNAs (circRNAs) have emerged as a promising platform for RNA-based therapeutics, ascribed to their excellent stability and prolonged protein translation capacity. However, modulation of circRNA translation remains a great challenge. Here, we develop a new chemically regulated circRNA translation system based on small ligand-induced stabilization of RNA-binding proteins (RBPs). The system is engineered by incorporating RNA motifs into an internal ribosomal entry site and fusing RBPs with small ligand-stabilized conditional proteins. We show that this design allows small ligand-modulated translation of circRNAs with a wide dynamic range and dose dependency. It is demonstrated that this strategy is modular and versatile to different RBPs and small-ligand-stabilized conditional proteins. We further employ this strategy to control the translation of functional proteins, including a guanine nucleotide exchange factor for modulating signaling pathways and a bispecific engager for regulating T cell activities. This system is highly modular and versatile, highlighting its great potential for basic research and therapeutic applications.