Chemically synthesized circular RNAs with phosphoramidate linkages enable rolling circle translation

2020 ◽  
Vol 56 (46) ◽  
pp. 6217-6220
Author(s):  
Kosuke Nakamoto ◽  
Naoko Abe ◽  
Genichiro Tsuji ◽  
Yasuaki Kimura ◽  
Fumiaki Tomoike ◽  
...  

Circular RNA without a stop codon enables rolling circle translation. we carried out one-pot chemical synthesis of circular RNA from RNA fragments. The synthesized circular RNAs acted as translation templates, despite the presence of unnatural phosphoramidate linkages.

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ruijiao Xin ◽  
Yan Gao ◽  
Yuan Gao ◽  
Robert Wang ◽  
Kathryn E. Kadash-Edmondson ◽  
...  

AbstractCircular RNAs (circRNAs) have emerged as an important class of functional RNA molecules. Short-read RNA sequencing (RNA-seq) is a widely used strategy to identify circRNAs. However, an inherent limitation of short-read RNA-seq is that it does not experimentally determine the full-length sequences and exact exonic compositions of circRNAs. Here, we report isoCirc, a strategy for sequencing full-length circRNA isoforms, using rolling circle amplification followed by nanopore long-read sequencing. We describe an integrated computational pipeline to reliably characterize full-length circRNA isoforms using isoCirc data. Using isoCirc, we generate a comprehensive catalog of 107,147 full-length circRNA isoforms across 12 human tissues and one human cell line (HEK293), including 40,628 isoforms ≥500 nt in length. We identify widespread alternative splicing events within the internal part of circRNAs, including 720 retained intron events corresponding to a class of exon-intron circRNAs (EIciRNAs). Collectively, isoCirc and the companion dataset provide a useful strategy and resource for studying circRNAs in human transcriptomes.


Life ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 103
Author(s):  
Benjamin D. Lee ◽  
Eugene V. Koonin

Viroids are a unique class of plant pathogens that consist of small circular RNA molecules, between 220 and 450 nucleotides in size. Viroids encode no proteins and are the smallest known infectious agents. Viroids replicate via the rolling circle mechanism, producing multimeric intermediates which are cleaved to unit length either by ribozymes formed from both polarities of the viroid genomic RNA or by coopted host RNAses. Many viroid-like small circular RNAs are satellites of plant RNA viruses. Ribozyviruses, represented by human hepatitis delta virus, are larger viroid-like circular RNAs that additionally encode the viral nucleocapsid protein. It has been proposed that viroids are direct descendants of primordial RNA replicons that were present in the hypothetical RNA world. We argue, however, that much later origin of viroids, possibly, from recently discovered mobile genetic elements known as retrozymes, is a far more parsimonious evolutionary scenario. Nevertheless, viroids and viroid-like circular RNAs are minimal replicators that are likely to be close to the theoretical lower limit of replicator size and arguably comprise the paradigm for replicator emergence. Thus, although viroid-like replicators are unlikely to be direct descendants of primordial RNA replicators, the study of the diversity and evolution of these ultimate genetic parasites can yield insights into the earliest stages of the evolution of life.


2005 ◽  
Vol 9 (2) ◽  
pp. 179-194 ◽  
Author(s):  
Biao Yu ◽  
Zunyi Yang ◽  
Hongzhi Cao
Keyword(s):  

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aijun Sun ◽  
Rui Wang ◽  
Shuaikang Yang ◽  
Xiaojing Zhu ◽  
Ying Liu ◽  
...  

AbstractMarek’s disease virus (MDV) induces severe immunosuppression and lymphomagenesis in the chicken, its natural host, and results in a condition that investigated the pathogenesis of MDV and have begun to focus on the expression profiling of circular RNAs (circRNAs). However, little is known about how the expression of circRNAs is referred to as Marek’s disease. Previous reports have is regulated during MDV replication. Here, we carried out a comprehensive profiling analysis of N6-methyladenosine (m6A) modification on the circRNA transcriptome in infected and uninfected chicken embryonic fibroblast (CEF) cells. Methylated RNA immunoprecipitation sequencing (MeRIP-Seq) revealed that m6A modification was highly conserved in circRNAs. Comparing to the uninfected group, the number of peaks and conserved motifs were not significantly different in cells that were infected with MDV, although reduced abundance of circRNA m6A modifications. However, gene ontology and Kyoto encyclopedia of genes and genomes (KEGG) pathway analyses revealed that the insulin signaling pathway was associated with the regulation of m6A modified circRNAs in MDV infection. This is the first report to describe alterations in the transcriptome-wide profiling of m6A modified circRNAs in MDV-infected CEF cells.


Author(s):  
Han-Wen Chen ◽  
Xiao-Xia Zhang ◽  
Zhu-Ding Peng ◽  
Zu-Min Xing ◽  
Yi-Wen Zhang ◽  
...  

AbstractTreatment of bone cancer pain (BCP) caused by bone metastasis in advanced cancers remains a challenge in clinical oncology, and the underlying mechanisms of BCP are poorly understood. This study aimed to investigate the pathogenic roles of circular RNAs (circRNAs) in regulating cancer cell proliferation and BCP development. Eight differentially expressed circRNAs in the rat spinal cord were validated by agarose gel electrophoresis and Sanger sequencing. Expression of circRNAs and mRNAs was detected by quantitative RT-PCR. MTS assay and flow cytometry were performed to analyze cell proliferation and apoptosis, respectively. Differentially expressed mRNA profiles were characterized by deep RNA sequencing, hierarchical clustering, and functional categorization. The interactions among circRNAs, microRNAs (miRNAs), and mRNAs were predicted using TargetScan. Additionally, western blot was performed to determine the protein levels of Pax8, Isg15, and Cxcl10. Multiple circRNAs were differentially expressed in the spinal cords of BCP model rats; of these, circSlc7a11 showed the greatest increase in expression. The overexpression of circSlc7a11 significantly promoted cell proliferation and repressed apoptosis of LLC-WRC 256 and UMR-106 cells, whereas circSlc7a11 silencing produced the opposite effects. Altered expression of circSlc7a11 also induced substantial changes in the mRNA expression profiles of LLC-WRC 256 cells; these changes were linked to multiple apoptotic processes and signaling pathways, such as the chemokine signaling pathway, and formed a complex circRNA/miRNA/mRNA network. Additionally, Pax8, Isg15, and Cxc110 protein level in LLC-WRC 256 cells was consistent with the mRNA results. The circRNA circSlc7a11 regulates rat BCP development by modulating LLC-WRC 256 cell proliferation and apoptosis through multiple-signaling mechanisms.


2020 ◽  
Vol 33 (11) ◽  
pp. 1047-1047
Author(s):  
Wan-yue Liu ◽  
Yi Sun ◽  
Shu-na Huang ◽  
Yu-zhen Lin ◽  
Hong-yan Guo ◽  
...  

Abstract Background To investigate the main environmental factors of hypertension and the relationship between hypertension and circular RNAs in peripheral blood lymphocytes. Methods This was a case–control study. A total of 681 hypertension patients and 485 subjects without hypertension were recruited between April 2017 and October 2018. All participations completed the questionnaire investigation, physical examination, and laboratory detection. Quantitative real-time polymerase chain reaction was used to analyze circRNAs (hsa_circ_0001946 and hsa_circ_0125589) in peripheral blood leukocytes in 84 hypertensives and 84 controls. Multivariate logistic regression and crossover analysis were used to analyze the interaction and association between environmental factors and circRNAs in hypertension. Results After adjusted by gender, age and marital status, overweight/obesity (odds ratio (OR) = 1.66, 95% confidence interval (CI) 1.24–2.22), abdominal obesity (OR = 2.17, 95% CI 1.54–3.04), anxiety (OR = 2.15, 95% CI 1.41–3.28), family history of hypertension (OR = 4.26, 95% CI 3.18–5.70), and higher levels of hsa_circ_0001946 (OR = 4.13, 95% CI 1.85–9.21) were risk factors for hypertension, while levels of hsa_circ_0125589 were not associated with hypertension. Crossover analysis showed that the risk of hypertension was 13.12 times higher (95% CI 3.89–44.23) in overweight subjects with high hsa_circ_0001946 levels compared with normal weight subjects with low hsa_circ_0001946 levels. Further, the risk of hypertension was 17.78 times higher (95% CI 1.88–168.61) in subjects with anxiety and high hsa_circ_0001946 levels. Conclusions Hypertension is the result of both environmental factors and genetic factors. Higher hsa_circ_0001946 levels, overweight and anxiety may increase the risk of hypertension, while hsa_circ_0125589 levels are not related to hypertension.


Author(s):  
Mingyi Zhou ◽  
Zhuo Yang ◽  
Danbo Wang ◽  
Peng Chen ◽  
Yong Zhang

Abstract Background As a novel type of non-coding RNA, circular RNAs (circRNAs) play a critical role in the initiation and development of various diseases, including cancer. However, the exact function of circRNAs in human cervical cancer remains largely unknown. Methods We identified the circRNA signature of upregulated circRNAs between cervical cancer and paired adjacent normal tissues. Using two different cohorts and GEO database, a total of six upregulated circRNAs were identified with a fold change > 2, and P < 0.05. Among these six circRNAs, hsa_circ_0072088 (circZFR) was the only exonic circRNA significantly overexpressed in cervical cancer. Functional experiments were performed to investigate the biological function of circZFR. CircRNA pull-down, circRNA immunoprecipitation (circRIP) and Co-immunoprecipitation (Co-IP) assays were executed to investigate the molecular mechanism underlying the function of circZFR. Results Functionally, circZFR knockdown represses the proliferation, invasion, and tumor growth. Furthermore, circRNA pull-down experiments combined with mass spectrometry unveil the interactions of circZFR with Single-Stranded DNA Binding Protein 1 (SSBP1). Mechanistically, circZFR bound with SSBP1, thereby promoting the assembly of CDK2/cyclin E1 complexes. The activation of CDK2/cyclin E1 complexes induced p-Rb phosphorylation, thus releasing activated E2F1 leading to cell cycle progression and cell proliferation. Conclusion Our findings provide the first evidence that circZFR is a novel onco-circRNA and might be a potential biomarker and therapeutic target for cervical cancer patients.


2021 ◽  
Vol 12 (9) ◽  
Author(s):  
Xuexiu Zhang ◽  
Jianning Yao ◽  
Haoling Shi ◽  
Bing Gao ◽  
Haining Zhou ◽  
...  

AbstractCircular RNAs (circRNAs) have been reported to play crucial roles in the progression of various cancers, including colorectal cancer (CRC). SP1 (Sp1 transcription factor) is a well-recognized oncogene in CRC and is deemed to trigger the Wnt/β-catenin pathway. The present study was designed to investigate the role of circRNAs which shared the same pre-mRNA with SP1 in CRC cells. We identified that hsa_circ_0026628 (circ_0026628), a circular RNA that originated from SP1 pre-mRNA, was upregulated in CRC cells. Sanger sequencing and agarose gel electrophoresis verified the circular characteristic of circ_0026628. Functional assays including CCK-8, colony formation, transwell, immunofluorescence staining, and sphere formation assay revealed the function of circ_0026628. RNA pull-down and mass spectrometry disclosed the proteins interacting with circ_0026628. Mechanistic assays including RIP, RNA pull-down, CoIP, ChIP, and luciferase reporter assays demonstrated the interplays between molecules. The results depicted that circ_0026628 functioned as a contributor to CRC cell proliferation, migration, EMT, and stemness. Mechanistically, circ_0026628 served as the endogenous sponge of miR-346 and FUS to elevate SP1 expression at the post-transcriptional level, thus strengthening the interaction between SP1 and β-catenin to activate the Wnt/β-catenin pathway. In turn, the downstream gene of Wnt/β-catenin signaling, SOX2 (SRY-box transcription factor 2), transcriptionally activated SP1 and therefore boosted circ_0026628 level. On the whole, SOX2-induced circ_0026628 sponged miR-346 and recruited FUS protein to augment SP1, triggering the downstream Wnt/β-catenin pathway to facilitate CRC progression.


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