RTCA (RNA 3'-terminal phosphate cyclase) is an RNA-modifying enzyme that catalyzes ATP-dependent conversion of RNA 3'-phosphate ends to 2',3'-cyclic phosphodiester products through a three-step adenylation mechanism 1. The enzyme functions in cellular RNA processing and repair pathways 1. RTCA also catalyzes 2'-phosphate cyclization, though at substantially slower rates, suggesting a role in end-healing during RNA repair 2. Functionally, RTCA plays a critical regulatory role in inhibiting central nervous system axon regeneration following injury. In Drosophila and mice, RTCA acts upstream of the mechanosensitive ion channel Piezo and the Rab10 GTPase to modulate Piezo expression and cell surface targeting; loss of RTCA promotes axon regeneration after spinal cord injury and optic nerve crush 3. Recent evidence reveals RTCA functions as an RNA-binding protein with surprising roles in modulating endogenous alternative splicing events across hundreds of genes 4. In bacterial systems, RTCA operates in a conserved RNA repair operon with RtcB ligase, where it is activated by tRNA fragments bearing cyclic phosphate ends generated during cellular stress or DNA damage 5. These findings establish RTCA as a multifunctional enzyme integrating RNA quality control, splicing regulation, and mechanotransduction signaling in neural regeneration.