Circular RNAs: New Players in Gene Regulation

Abstract

The existence of circular RNAs (circRNAs) was demonstrated over 30 years ago. They did not gain much interest at the time because they appeared to be relatively rare when compared to the abundance of the canonical linear RNAs. However, more recent evidence suggests that circRNAs are abundant in cells and tissues and possess intriguing biological properties. These recent developments have renewed our interest in this novel class of molecules. This report will provide an overview of circRNAs, discuss how they may modify our understanding of gene regulation and indicate their most likely relevance to health. The circRNAs from viruses, bacteria and archaea are not in the scope of this report, and we focused this review on circRNAs in eukaryotes.

Identification of Circular RNAs from the Parental Genes Involved in Multiple Aspects of Cellular Metabolism in Barley

“…Most recent contributions have revealed the regulated levels of circular RNAs implying the on-purpose production of circular RNAs in animal cells (Conn et al, 2015 ; You et al, 2015 ). In mammals, circular RNAs are involved in the positive regulation of gene expression at the transcriptional and post-transcriptional levels (Hansen et al, 2013 ; Memczak et al, 2013 ; Andreeva and Cooper, 2015 ; Li et al, 2015 ). Additionally, circular RNAs can suppress the expression of genes (Ashwal-Fluss et al, 2014 ).…”

Comprehensive circRNA expression profile and construction of circRNA‐associated ceRNA network in fur skin

“…Recently, the central regulatory role of circRNA in RNA changed from being perceived as a rare curiosity to detecting the details of metabolic mechanisms . The functional capacity of circRNAs shows that they are distributed in various tissues and cell types, such as archaea, human, mouse, drosophila and nematodes …”

“…[13,26] The functional capacity of circRNAs shows that they are distributed in various tissues and cell types, such as archaea, [13] human, [27] mouse, [11] drosophila [28] and nematodes. [6] The relationships between circRNAs and the brain, [29] liver [30] and heart [31] have been recognized. Recently, the role of circRNAs in cancer was also highlighted.…”

“…A growing component of this family of diverse RNA molecules is the circRNA, which has a stable structure formed by special loop splicing. Many circRNAs have been identified across different eukaryotic organisms in various metabolism pathways . The 3′ and 5′ ends of circRNAs are not free but covalently joined in a “backsplice” and “head‐to‐tail splice” manner .…”

“…Many circRNAs have been identified across different eukaryotic organisms in various metabolism pathways. [6] The 3′ and 5′ ends of circRNAs are not free but covalently joined in a "backsplice" and "head-to-tail splice" manner. [7] Therefore, circRNAs are not degraded by RNase (ribonuclease), which digests linear RNAs.…”