RNA is frequently chemically modified, with over 170 types of chemical modifications identified to date in cellular RNAs. These modifications, along with their effector proteins, constitute new layers of gene expression regulation by controlling either the fate of modified RNAs at nearly every stage of their life cycle or local transcription through modulating the nearby chromatin state and transcriptional complexes. This is especially evident in dynamic biological contexts such as cellular state transitions, signaling, immune responses, and stress adaptation.