circRNA

circRNAs are a special class of non-coding RNA molecules, which have a closed ring structure and exist in large quantities in the eukaryotic transcriptome. Most circRNAs are composed of exon sequences, which are conserved in different species, and have expression specificity in different tissues and developmental stages. Because circRNA is not sensitive to nucleases, it is structurally more stable than linear RNA. With the advancement of  bioinformatics and high-throughput sequencing technology, a large number of circRNAs have been discovered and identified by researchers, and the understanding of their functions has increased with the identification. On the one hand, circRNA binds to corresponding microRNA, absorbing miRNA like a "sponge", so that miRNA cannot bind to target genes, and then jointly participate in regulating the expression of target genes; on the other hand, it directly regulates the level of other RNAs through complementary base pairing or interacts with RNA-binding proteins (RBPs) to affect gene expression. In summary, circRNA may be an objective clinical diagnostic marker and a valuable target for disease diagnosis and treatment.