I Introduction
Circular RNA (circRNA) is a type of noncoding RNA that differs from linear RNA. It was initially found in 1976 in the Sendai virus [1]. CircRNAs have a covalent closed loop structure, without 5’ cap and 3’ polyadenylated tails [2]. Subsequent studies have identified the presence of circular RNA in humans [3], mice [4], fungi, and a variety of other tissues and cells. Due to the limitations of earlier techniques, researchers initially believed that circRNA had no biological importance and was simply a transcriptional consequence of aberrant splicing [4], [5]. CircRNAs have been revealed to play a crucial role in the regulation of gene expression through developments in high-throughput sequencing methods and associated studies [6], [7].