Fig. 3

CircRNAs have multiple functions, such as: A they sponge the molecular function of RNA-binding proteins through specific interactions; B they act as miRNA sponges in the cytoplasm by binding miRNAs and preventing them from repressing target messenger RNAs; C By serving as a scaffold for interactions between enzymes and substrates, they improve reaction kinetics; D They are translated using rolling circle amplification when they have internal ribosome entry sites or m6A RNA modification of the 5ʹ-untranslated regions; E In the nucleus, FECR1 enhance the activity of methylases and demethylases by attaching to the gene promoter-chromatin complex; F promote RNA polymerase II activity by cooperating with the small nuclear ribonucleoprotein U1 or promoting RNA Pol II elongation machinery, as observed with ci-ankrd52, sircEIF3J, and circPAIP2; G In the nucleus, cia-cGAS sponge cyclic GMP–AMP synthase (cGAS)