Metabolic Labeling and Imaging of Cellular RNA via Bioorthogonal Cyclopropene-Tetrazine Ligation

RNA labeling is vital for the study of an RNA structure, cellular distribution, localization, and metabolism. Herein, we report N6 cyclopropane-modified adenosine (cpA) as a new analog for metabolic RNA labeling. We successfully applied inverse electron-demand Diels-Alder (iEDDA) chemistry to label cellular RNA with cpA. This labeling technique is practical and provides a new platform to study RNA roles in cells in a metal-free manner. This simple and robust assay represents a significant advancement in the profiling methods of the nascent transcriptome using chemical approaches.