How are circRNA formed?
A circRNA is formed by a backsplice event. Spliceosome-mediated splicing joins a 5′ splice site (splice donor) of a downstream exon with a 3′ splice site (splice acceptor) of an upstream exon to yield a circular RNA with a “scrambled exon” junction between exon 4 and exon 2.
How do you identify circRNA?
In single-end RNA-seq data, circRNAs can only be identified by reads aligned to the backsplice junction, as all other reads may have been generated by either a linear or a circular isoform.
Why is circular RNA more stable?
Because circular RNA does not have 5′ or 3′ ends, it is resistant to exonuclease-mediated degradation and is presumably more stable than most linear RNA in cells. Circular RNA has been linked to some diseases such as cancer.
How does circRNA work?
Many studies have shown that the most general function of circRNAs is its action as a miRNA sponge to regulate target gene expression by inhibiting miRNA activity. One circRNA can regulate one or multiple miRNAs through multiple miRNA binding sites.
What is back splicing RNA?
Circular RNAs (circRNAs) are generated by a specific type of splicing called back-splicing, wherein the 5′ terminus of a pre-mRNA upstream exon is non-colinearly spliced with the 3′ terminus of a downstream exon (Fig. 1).
How is circular RNA degraded?
The high stability of circular RNA is rendered by its closed ends; they are nevertheless prone to degradation by circulating endonucleases in serum or exosomes or by microRNA-mediated cleavage due to their high complementarity.
What is back-splicing RNA?
What is exon scrambling?
Exon scrambling is a phenomenon of gene expression in which exons are found to be spliced at correct sites but joined together in an order different from that predicted by the genomic DNA sequence.
How many types of circular RNA are there?
three main types
circRNA Classification Studies have identified three main types of circRNA: ecircRNA, circular intronic RNA (ciRNA), and exon–intron circRNA (EIciRNA) (Figure 1).
What is a cryptic exon?
Cryptic exons are considered splicing variants that may introduce frameshifts or stop codons, among other changes in the resulting mRNA. These aberrant mRNA have been demonstrated in motor cortex and middle temporal gyrus of ALS and FTLD patients [1].
How does RNase R work?
RNase R ensures translation accuracy, correct rRNA maturation and elimination of abnormal rRNAs, and is employed by the trans-translation system to break down damaged mRNAs.