Fig. 1

Biogenesis of circRNAs. a circRNAs formation can occur through RBPs mediated folding of the pre-miRNA. b the pairing between the two introns flanking the circularized exons, which have a complementary inverted sequence, can promote the backsplicing proceed in cis. c the back-splicing site promotes the joining of the downstream 5’donor sites with the upstream 3’acceptor sites. The lariat is subsequently processed by internal splicing, which finally results in the release of ecircRNAs or EIciRNAs. d tricRNA exon termini link with each other to form a mature tRNA, and intron termini are ligated together to form tricRNA