Table 1 CircRNAs classification.
From: Going circular: history, present, and future of circRNAs in cancer
Category | Abbreviations | Cellular compartment | Mechanism of biogenesis | Ref |
|---|---|---|---|---|
Exon-derived circRNAs | ecircRNA | Cytoplasm | 1–5 exon circularization | |
Exon–intron circRNAs | EIciRNA | Nucleus | Intronic excision failure followed by intronic retention in the nascent circRNAs | [68] |
Intronic circRNAs | ciRNA | Nucleus | Intron lariats escaping the usual intron debranching and following degradation | |
Intergenic circRNAs | / | / | From intergenic genomic portions and formed by two intronic circRNA fragments flanked by GT-AG (CT-AC) splicing signals acting as the splice donor and acceptor of the circular junction in the process of forming an integrated circRNA | |
Read-through circRNAs | rt-circRNA | Cytoplasm | Read-through of polymerase that includes exons from adjacent genes | |
Fusion-circRNAs | f-circRNAs | Cytoplasm/ Nucleus | Cancer-associated chromosomal translocation |
