Fig. 3

Structural characteristics and biological functions of circRNAs. Inside the cell, circular RNAs have many multiple roles to do. In the nucleus, circRNAs can silence a specific locus by interacting with the histone methylation pattern. They can also control the transcription of their own gene by interacting with RNA polymerase II. Finally, alternative splicing can be blocked by their competition with mRNA for splice sites. CircRNAs are found in the cytoplasm, where they can function as miRNA sponges, decoy certain transcription factors, be translated into proteins, bind with RNA-binding proteins to regulate translation of particular mRNAs, and serve as protein scaffolds. In addition to promoting cell death by interfering with the processing of pre-rRNA components, circRNAs can bind to some proteins and inhibit their signal transduction activity