Circular RNAs from transcripts of the rat cytochrome P450 2C24 gene: correlation with exon skipping.

Abstract

The cytochrome P450 2C24 gene is characterized by the capability to generate, in rat kidney, a transcript containing exons 2 and 4 spliced at correct sites but having the

Circular RNAs: diversity of form and function

“…This process is referred to as backsplicing. Backspliced RNAs were first detected on specific genes as cases wherein the exons were joined together in something other than an expected linear order, so-called "scrambled exons" or "exon shuffling" (Nigro et al 1991;Cocquerelle et al 1992Cocquerelle et al , 1993Capel et al 1993;Zaphiropoulos 1996Zaphiropoulos , 1997. Genome-wide RNA-sequencing analysis has now suggested there are a staggering number of circles produced by backsplicing ( Table 2; Salzman et al 2012Salzman et al , 2013Jeck et al 2013;Memczak et al 2013; Ashwal-Fluss et al Guo et al 2014;Zhang et al 2014).…”

“…A gene that gives rise to a circRNA could encode a single isoform, or many (Salzman et al 2013;Zhang et al 2014). Some, but not all, are associated with exon skipping alternative splicing of the corresponding linear transcript (Zaphiropoulos 1996). Some circRNAs contain some of the same exons as annotated mRNAs, and some are from noncoding RNAs.…”

The emerging role and clinical implication of human exonic circular RNA

“…Only a small number of circRNAs in different organisms have been identified, and they were generally disregarded as the results of mis-splicing and as by-products of pre-mRNA processing. [3][4][5][6] However, recent advances using biochemical enrichment strategies and novel bioinformatics approaches coupled with deep sequencing have allowed comprehensive investigation of circRNAs. [7][8][9][10] Specifically, a large number of circRNAs have been successfully identified in various cell lines and across different species.…”

Circular RNAs: Unexpected outputs of many protein-coding genes

“…The length of the skipped exon appears to be one key determinant, 41 but other factors such as RNA secondary structures and the speed of lariat debranching are also likely to be involved. Interestingly, a correlation between exon skipping and circular RNA biogenesis has been noted at other genes 49,50,52,55 and in a global transcriptome analysis of human endothelial cells. 90 Detailed analyses are now required to determine if re-splicing truly occurs at these loci.…”

“…This was the first hint that the dominant output of a gene could, in some cases, be a circular RNA rather than a linear mRNA. 48 A handful of additional circular RNAs were identified over the ensuing years [49][50][51][52][53][54][55][56] until deep sequencing efforts combined with new computational algorithms all of a sudden revealed thousands of previously missed circular RNAs from eukaryotic cells. 13,14,27,29,31,33,40,57,58 Over 25,000 putative circular RNAs, derived from »15% of actively transcribed genes, were identified in human fibroblasts alone.…”