Fig. 1
From: CircRNAs: versatile players and new targets in organ fibrosis
Illustrations of different categories of circRNA. ①EcircRNA is formed by the back-splicing of exons; ②EIciRNA is circularized with introns “retained” between exons; ③ciRNA is formed by the back-splicing of the intron; ④rt-circRNA is a hybrid circle that includes coding exons from two adjacent and similarly oriented genes. ⑤f-circRNA is generated from transcribed exons of distinct genes affected by translocations. ⑥TricRNA is derived from pretRNA, which is recognized and cleaved by TSEN and produces 5’-OH and a 2’,3’-cyclic phosphate at each site of cleavage. Ligation of these two cleavage sites generates a circle. ⑦mecci-RNA refers to mtDNA-encoded or mitochondria-located circRNAs. SA splicing acceptor, SD splicing donor, EcirRNA exon circRNA, EIciRNA exon‒intron circRNA, ciRNA intronic circRNA, rt-circRNA read-through circRNA, f-circRNA fused circRNA, tricRNA tRNA intronic circular RNA, mecciRNA mitochondrial circRNA