Structure, Regulation, and Function of Linear and Circular Long Non-Coding RNAs.

Tao Qin,Ke-Qin Zhang,Juan Li

doi:10.3389/fgene.2020.00150

Abstract

Long non-coding RNAs (lncRNAs), including linear lncRNAs and circular RNAs (circRNAs), exhibit a surprising range of structures. Linear lncRNAs and circRNAs are generated by different pathways. Linear lncRNAs perform functions that depend on their specific sequences, transcription, and DNA elements of their gene loci. In some cases, linear lncRNAs contain a short open reading frame encoding a peptide. circRNAs are covalently closed RNAs with tissue-specific and cell-specific expression patterns that have recently been extensively investigated. Pioneering work focusing on their biogenesis and functional characterization indicates that circRNAs regulate cell development via multiple mechanisms and play critical roles in the immune system. Furthermore, circRNAs in exosomes function on target cells. As with linear lncRNAs, specific circRNAs can also be translated. In this review, we summarize current understanding and highlight the diverse structure, regulation, and function of linear lncRNAs and circRNAs.

Highlights

The central dogma of molecular biology describes the relationship between the informational macromolecules, DNA and RNA, and the transfer of the encoded information into proteins (Crick, 1970)
Most well-characterized linear Long non-coding RNAs (lncRNAs) are transcribed by RNA polymerase II (Pol II) and are presumably capped, polyadenylated, and contain exon-exon splice junctions like mRNAs (Chen, 2016)
Recent studies suggest that some lncRNAs can form as a circle and can function as a sponge to recruit miRNAs or transcriptional effectors to regulate target gene expression

Summary

Introduction

The central dogma of molecular biology describes the relationship between the informational macromolecules, DNA and RNA, and the transfer of the encoded information into proteins (Crick, 1970). Linear lncRNAs have diverse functions, including maintaining nuclear structure integrity (Clemson et al, 2009; Lei et al, 2013), positively or negatively regulating genes in cis or in trans by recruiting transcription factors or chromatinmodifying complexes to DNA targets in the nucleus (Long et al, 2017), acting as decoys to sequester RNA binding proteins (RBPs), or directly interacting with DNA (Chen, 2016; Cloutier et al, 2016).

Results

Conclusion