The design and synthesis of circular RNAs

Obi, Prisca; Chen, Y Grace

doi:10.1016/j.ymeth.2021.02.020

Cited by 81 publications

(65 citation statements)

References 134 publications

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“…CircRNAs were first discovered in mammals in 1991. Nigro et al identified several abnormally spliced transcripts, in which exons from a candidate tumor suppressor gene (DCC) were scrambled during the splicing process in vivo (Nigro et al, 1991). After that, more circRNAs were found in mammalian cells (Cocquerelle et al, 1992;Capel et al, 1993;Zaphiropoulos, 1996;Zaphiropoulos, 1997;Surono et al, 1999).…”

Section: A Brief History Of Circrnasmentioning

confidence: 99%

“…After that, more circRNAs were found in mammalian cells (Cocquerelle et al, 1992;Capel et al, 1993;Zaphiropoulos, 1996;Zaphiropoulos, 1997;Surono et al, 1999). However, since the expression level of these circRNAs observed was so low, researchers believed that these circRNAs were the products of aberrant RNA splicing (Nigro et al, 1991;Cocquerelle et al, 1993). Therefore, researchers only knew the existence of circRNAs, but had no further understanding of theirs functions or impacts, and circRNAs did not receive much attention.…”

Section: A Brief History Of Circrnasmentioning

confidence: 99%

“…At present, the main method of circRNA synthesis in vitro is ligating the ends of linear RNA precursor to produce a covalently closed circle. Linear RNA can be produced by chemical synthesis ( Müller and Appel, 2017 ; Obi and Chen, 2021 ) or enzymatic strategy ( Obi and Chen, 2021 ). The advantage of chemical synthesis is that the 5′ monophosphate can be directly introduced during the synthesis process for future cyclization.…”

Section: Synthesis Of Circrnas In Vitromentioning

confidence: 99%

“…Therefore, this method can enable more accurate linear RNA precursor ligation. However, this method forms 2′, 5′-phosphodiester bonds at the ligation site instead of the natural 3′, 5′-phosphodiester bonds, and the mechanism remains unclear in vitro ( Petkovic and Müller, 2015 ; Müller and Appel, 2017 ; Obi and Chen, 2021 ). At present, there are few studies concentrating on group II introns.…”

Section: Synthesis Of Circrnas In Vitromentioning

confidence: 99%

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Circular RNA: Biosynthesis in vitro

Chen

2021

Front. Bioeng. Biotechnol.

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Circular RNA (circRNA) is a unique type of noncoding RNA molecule. Compared with traditional linear RNA, circRNA is a covalently closed circle produced by a process called backsplicing. CircRNA is abundant in many cells and has rich functions in cells, such as acting as miRNA sponge, protein sponge, protein scaffold, and mRNA regulator. With the continuous development of circRNA study, circRNA has also played an important role in medical applications, including circRNA vaccines and gene therapy. In this review, we illustrate the synthesis of circRNAs in vitro. We focus on biological ligation methods, such as enzymatic ligation from the bacteriophage T4 and ribozyme method. In addition, we summarize the current challenges in the design, synthesis, application, and production of circRNAs, and propose possible solutions in the future. CircRNA is expected to play an essential role in basic research and medical applications.

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Section: A Brief History Of Circrnasmentioning

confidence: 99%

Section: A Brief History Of Circrnasmentioning

confidence: 99%

Section: Synthesis Of Circrnas In Vitromentioning

confidence: 99%

Section: Synthesis Of Circrnas In Vitromentioning

confidence: 99%

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Circular RNA: Biosynthesis in vitro

Chen

2021

Front. Bioeng. Biotechnol.

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“…In the second step, the end was previously generated in the 3′-hydroxyl from the circularizing exon attacks the 3′ splice site, resulting in the release of the circular exon that has covalently joined ends [ 29 ]. The efficiency of backsplicing will depend on the general secondary structure of the pre-mRNA transcript and thus varies with the pairing of different exon sequences and intron structures [ 30 ]. Unlike linear RNAs, circRNAs are more stable in that they form covalently closed continuous RNA loops, and, therefore, are inherent to exonucleolytic degradation of RNA [ 26 , 27 , 31 , 32 , 33 ].…”

Section: Introductionmentioning

confidence: 99%

Synthetic Circular miR-21 Sponge as Tool for Lung Cancer Treatment

Rama

Quiñonero

Mesas

et al. 2022

IJMS

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Lung cancer is the most common cancer in the world and several miRNAs are associated with it. MiRNA sponges are presented as tools to inhibit miRNAs. We designed a system to capture miRNAs based on circular RNAs (circRNA). To demonstrate its usefulness, we chose miR-21, which is upregulated and implicated in lung cancer. We constructed a miR-21 sponge and inserted it into a vector that facilitates circular RNA production (Circ-21) to study its effect on growth, colony formation, and migration in lung cancer cell lines and multicellular tumor spheroids (MTS). Circ-21 induced a significant and time-dependent decrease in the growth of A549 and LL2 cells, but not in L132 cells. Furthermore, A549 and LL2 cells transfected with Circ-21 showed a lower number of colonies and migration than L132. Similar findings were seen in A549 and LL2 Circ-21 MTS, which showed a significant decrease in volume growth, but not in L132 Circ-21 MTS. Based on this, the miR-21 circular sponge may suppress the processes of tumorigenesis and progression. Therefore, our system based on circular sponges seems to be effective, as a tool for the capture of other miRNAs.

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Tactics targeting circular mRNA biosynthesis

Chen

Wang

2023

Biotech & Bioengineering

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Faced with the development of mRNA technology in the field of medicine and vaccine, circular mRNA (circmRNA) becomes a strong alternative to mRNA for its circular secondary structure and higher stability. At present, the synthesis of circmRNAs has been realized by ligating linear mRNA precursors and is limited by poor efficiency. To solve this challenge, this study started with ribozyme catalysis and enzymatic reaction to explore different circmRNA biosynthesis strategies. In terms of ribozyme method, by screening different group I intron self‐splicing system sequences, the sequence from thymidylate synthase (Td) gene of phage T4 showed the highest ligation efficiency. In terms of enzyme method, with the help of 20‐bp homologous arm, T4 Rnl 2 was determined as the ligation method with the highest ligation efficiency. By comparing the two ligation methods, the expression level of circmRNA ligated by T4 Rnl 2 was 86% higher than that ligated by Td ribozyme. Based on these ligation methods, the screening results of internal ribosome entry site (IRES) sequences showed that mud crab dicistrovirus IRES was an IRES sequence with high ribosome binding ability and could be widely used in circmRNAs for efficient and stable translation in mammalian cells. These results should provide positive guidance for the industrial production of circmRNAs and the development of mRNA vaccines. Eventually, circmRNAs could widely function in the field of biomedicine.

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The design and synthesis of circular RNAs

Cited by 81 publications

References 134 publications

Circular RNA: Biosynthesis in vitro

Circular RNA: Biosynthesis in vitro

Synthetic Circular miR-21 Sponge as Tool for Lung Cancer Treatment

Tactics targeting circular mRNA biosynthesis

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