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How can circular RNAs affect gene regulation?

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Diagram of a DNA polynucleotide chain showing linked deoxyribose sugars, phosphate groups, and nitrogenous bases (adenine, guanine, cytosine, thymine), with an inset comparing ribose and uracil in RNA. — Nucleic acid A portion of the polynucleotide chain of deoxyribonucleic acid (DNA), with an inset showing the corresponding pentose sugar and pyrimidine base in ribonucleic acid (RNA).

Circular RNA (circRNA) is a unique type of RNA characterized by a loop structure formed by the bonding of its 5′ and 3′ ends. These molecules influence gene regulation through several distinct mechanisms:

miRNA Sponging: CircRNAs can bind to micro RNA (miRNA) molecules, acting as "sponges" that sequester them and prevent the miRNAs from binding to their intended targets.
Transcriptional and Splicing Regulation: They play a significant role in regulating the transcription and alternative splicing of the specific genes from which they are derived.
Protein Synthesis: While primarily regulatory, some circRNAs can also serve as templates for protein synthesis, functioning similarly to messenger RNA.1