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

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.

RNA-Based Technologies for Engineering Plant Virus Resistance

“…While the small siRNAs and miRNAs constitute important classes of regulatory ncRNA, many other types of ncRNAs are known, and all of these form the majority of the transcriptome, given that only about 2% of transcribed RNAs encode proteins [ 7 ]. ncRNAs also include well-known classes of RNAs involved in translation such as tRNAs and rRNA, small nuclear RNAs (snRNAs) involved in RNA splicing, and small nucleolar RNAs (snoRNAs) mostly involved in the regulation of posttranscriptional modification of rRNAs [ 8 ]. In addition, the plant genome encodes tens of thousands of long ncRNAs (lncRNAs; >200 nt in length) which include linear and circular lncRNAs with no or little coding capacity [ 9 ].…”

“…Thus, while the central dogma of DNA>RNA>protein still holds true, ncRNAs can greatly influence this information flow and are, therefore, now an emerging major new source of next-generation targets which may be exploited in diverse applications, including conferring plant resistance against pathogens and viruses in particular [ 8 ].…”

Characteristics and expression profiles of circRNAs during abdominal adipose tissue development in Chinese Gushi chickens

“…At present, the function of circRNAs in the development or deposition of animal adipose tissue has not been fully elucidated. The expression of circRNAs is known to have obvious tissue or cell specificity [ 15 ]. Therefore, the identification of circRNAs related to adipose tissue development in economically important animals is an important step to better study circRNA function in the formation of adipose tissue-related traits.…”

Long Non-coding RNA ST8SIA6-AS1 Promotes Lung Adenocarcinoma Progression Through Sponging miR-125a-3p

“…Most lncRNAs have obvious spatiotemporal expression specificity during tissue differentiation and development ( Quinn and Chang, 2016 ). Recent studies have shown that lncRNA is involved in many important regulatory processes such as chromosome silencing, genome imprinting, chromatin modification, transcription activation/interference, and nuclear transport ( Bhan et al, 2017 ; Qin et al, 2020 ). The mechanism of action of lncRNA is extremely complicated and has not yet been fully understood, among which the well-verified one is that lncRNA can act as a miRNA molecular sponge and regulate the expression of miRNA targets ( Thomson and Dinger, 2016 ).…”