1. What are circRNAs ?
Circular RNAs are a novel group of abundant, stable, and evolutionary conservative noncoding RNAs. Unlike linear RNA, circular RNA lacks 5' cap and 3' poly(A) tail, it is an RNA molecule with 3' and 5' ends covalently linked in a circle.
Most human pre-mRNAs are spliced into linear molecules that retain the exon order defined by the genomic sequence. By deep sequencing of RNA from a variety of normal and malignant human cells, we found RNA transcripts from many human genes in which the exons were arranged in a non-canonical order.
What's more, recent researchs suggest that circular RNAs play different roles in gene regulation, such as function as miRNA sponges, regulate gene transcription and interact with RNA binding proteins.
Further research on the mechanism of formation and function about circRNA will help us understand the complexity of life activity at the transcriptional level.