Fig. 1
From: Emerging roles of exosomal circRNAs in non-small cell lung cancer
Biogenesis and functions of circRNAs. CircRNAs form EIciRNAs, EcircRNAs, and CiRNAs through four hypothesized mechanisms: intron pairing-driven circulation, RNA-driven circularization, lariat-driven circularization and circularization intronic RNA. Reverse direct splicing or RNA-binding proteins (RBPs) bind to specific motifs in flanking introns, promoting RNA-driven circularization. Splicing intermediates known as lariat precursors, which result from intronic lariat precursors that elude the debranching stage of canonical linear splicing or from an exon-skipping event during linear splicing, can also produce circRNAs. CiRNAs are generated by the retention of a 7 nt GU-rich element and an 11 nt C-rich element. CircRNAs can be sponges, interact with proteins, regulate gene expression, and translate proteins. They serve as biomarkers, therapeutic targets, and therapeutic agents. Detailed information on circRNAs was sourced from Lingling Chen