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Digby B, Finn S, Ó Broin P. Computational approaches and challenges in the analysis of circRNA data. BMC Genomics 2024; 25:527. [PMID: 38807085 PMCID: PMC11134749 DOI: 10.1186/s12864-024-10420-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Accepted: 05/15/2024] [Indexed: 05/30/2024] Open
Abstract
Circular RNAs (circRNA) are a class of non-coding RNA, forming a single-stranded covalently closed loop structure generated via back-splicing. Advancements in sequencing methods and technologies in conjunction with algorithmic developments of bioinformatics tools have enabled researchers to characterise the origin and function of circRNAs, with practical applications as a biomarker of diseases becoming increasingly relevant. Computational methods developed for circRNA analysis are predicated on detecting the chimeric back-splice junction of circRNAs whilst mitigating false-positive sequencing artefacts. In this review, we discuss in detail the computational strategies developed for circRNA identification, highlighting a selection of tool strengths, weaknesses and assumptions. In addition to circRNA identification tools, we describe methods for characterising the role of circRNAs within the competing endogenous RNA (ceRNA) network, their interactions with RNA-binding proteins, and publicly available databases for rich circRNA annotation.
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Affiliation(s)
- Barry Digby
- School of Mathematical and Statistical Sciences, University of Galway, Galway, Ireland.
| | - Stephen Finn
- Discipline of Histopathology, School of Medicine, Trinity College Dublin and Cancer Molecular Diagnostic Laboratory, Dublin, Ireland
| | - Pilib Ó Broin
- School of Mathematical and Statistical Sciences, University of Galway, Galway, Ireland
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Drula R, Braicu C, Neagoe IB. Current advances in circular RNA detection and investigation methods: Are we running in circles? WILEY INTERDISCIPLINARY REVIEWS. RNA 2024; 15:e1850. [PMID: 38702943 DOI: 10.1002/wrna.1850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 03/30/2024] [Accepted: 04/01/2024] [Indexed: 05/06/2024]
Abstract
Circular RNAs (circRNAs), characterized by their closed-loop structure, have emerged as significant transcriptomic regulators, with roles spanning from microRNA sponging to modulation of gene expression and potential peptide coding. The discovery and functional analysis of circRNAs have been propelled by advancements in both experimental and bioinformatics tools, yet the field grapples with challenges related to their detection, isoform diversity, and accurate quantification. This review navigates through the evolution of circRNA research methodologies, from early detection techniques to current state-of-the-art approaches that offer comprehensive insights into circRNA biology. We examine the limitations of existing methods, particularly the difficulty in differentiating circRNA isoforms and distinguishing circRNAs from their linear counterparts. A critical evaluation of various bioinformatics tools and novel experimental strategies is presented, emphasizing the need for integrated approaches to enhance our understanding and interpretation of circRNA functions. Our insights underscore the dynamic and rapidly advancing nature of circRNA research, highlighting the ongoing development of analytical frameworks designed to address the complexity of circRNAs and facilitate the assessment of their clinical utility. As such, this comprehensive overview aims to catalyze further advancements in circRNA study, fostering a deeper understanding of their roles in cellular processes and potential implications in disease. This article is categorized under: RNA Methods > RNA Nanotechnology RNA Methods > RNA Analyses in Cells RNA Methods > RNA Analyses In Vitro and In Silico.
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Affiliation(s)
- Rareș Drula
- Research Center for Functional Genomics, Biomedicine and Translational Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Cornelia Braicu
- Research Center for Functional Genomics, Biomedicine and Translational Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Ioana-Berindan Neagoe
- Research Center for Functional Genomics, Biomedicine and Translational Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
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Zhong Y, Yang Y, Wang X, Ren B, Wang X, Shan G, Chen L. Systematic identification and characterization of exon-intron circRNAs. Genome Res 2024; 34:376-393. [PMID: 38609186 PMCID: PMC11067877 DOI: 10.1101/gr.278590.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 03/07/2024] [Indexed: 04/14/2024]
Abstract
Exon-intron circRNAs (EIciRNAs) are a circRNA subclass with retained introns. Global features of EIciRNAs remain largely unexplored, mainly owing to the lack of bioinformatic tools. The regulation of intron retention (IR) in EIciRNAs and the associated functionality also require further investigation. We developed a framework, FEICP, which efficiently detected EIciRNAs from high-throughput sequencing (HTS) data. EIciRNAs are distinct from exonic circRNAs (EcircRNAs) in aspects such as with larger length, localization in the nucleus, high tissue specificity, and enrichment mostly in the brain. Deep learning analyses revealed that compared with regular introns, the retained introns of circRNAs (CIRs) are shorter in length, have weaker splice site strength, and have higher GC content. Compared with retained introns in linear RNAs (LIRs), CIRs are more likely to form secondary structures and show greater sequence conservation. CIRs are closer to the 5'-end, whereas LIRs are closer to the 3'-end of transcripts. EIciRNA-generating genes are more actively transcribed and associated with epigenetic marks of gene activation. Computational analyses and genome-wide CRISPR screening revealed that SRSF1 binds to CIRs and inhibits the biogenesis of most EIciRNAs. SRSF1 regulates the biogenesis of EIciLIMK1, which enhances the expression of LIMK1 in cis to boost neuronal differentiation, exemplifying EIciRNA physiological function. Overall, our study has developed the FEICP pipeline to identify EIciRNAs from HTS data, and reveals multiple features of CIRs and EIciRNAs. SRSF1 has been identified to regulate EIciRNA biogenesis. EIciRNAs and the regulation of EIciRNA biogenesis play critical roles in neuronal differentiation.
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Affiliation(s)
- Yinchun Zhong
- Department of Cardiology, The First Affiliated Hospital of USTC, Division of Life Science and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Yan Yang
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Clinical Laboratory, The First Affiliated Hospital of USTC, School of Basic Medical Sciences, Division of Life Science and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Xiaolin Wang
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Clinical Laboratory, The First Affiliated Hospital of USTC, School of Basic Medical Sciences, Division of Life Science and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Bingbing Ren
- Department of Pulmonary and Critical Care Medicine, Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China
| | - Xueren Wang
- Department of Anesthesiology, Shanxi Bethune Hospital, Taiyuan 030032, China;
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Ge Shan
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Clinical Laboratory, The First Affiliated Hospital of USTC, School of Basic Medical Sciences, Division of Life Science and Medicine, University of Science and Technology of China, Hefei 230027, China;
| | - Liang Chen
- Department of Cardiology, The First Affiliated Hospital of USTC, Division of Life Science and Medicine, University of Science and Technology of China, Hefei 230027, China
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Rigden DJ, Fernández XM. The 2024 Nucleic Acids Research database issue and the online molecular biology database collection. Nucleic Acids Res 2024; 52:D1-D9. [PMID: 38035367 PMCID: PMC10767945 DOI: 10.1093/nar/gkad1173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 11/23/2023] [Indexed: 12/02/2023] Open
Abstract
The 2024 Nucleic Acids Research database issue contains 180 papers from across biology and neighbouring disciplines. There are 90 papers reporting on new databases and 83 updates from resources previously published in the Issue. Updates from databases most recently published elsewhere account for a further seven. Nucleic acid databases include the new NAKB for structural information and updates from Genbank, ENA, GEO, Tarbase and JASPAR. The Issue's Breakthrough Article concerns NMPFamsDB for novel prokaryotic protein families and the AlphaFold Protein Structure Database has an important update. Metabolism is covered by updates from Reactome, Wikipathways and Metabolights. Microbes are covered by RefSeq, UNITE, SPIRE and P10K; viruses by ViralZone and PhageScope. Medically-oriented databases include the familiar COSMIC, Drugbank and TTD. Genomics-related resources include Ensembl, UCSC Genome Browser and Monarch. New arrivals cover plant imaging (OPIA and PlantPAD) and crop plants (SoyMD, TCOD and CropGS-Hub). The entire Database Issue is freely available online on the Nucleic Acids Research website (https://academic.oup.com/nar). Over the last year the NAR online Molecular Biology Database Collection has been updated, reviewing 1060 entries, adding 97 new resources and eliminating 388 discontinued URLs bringing the current total to 1959 databases. It is available at http://www.oxfordjournals.org/nar/database/c/.
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Affiliation(s)
- Daniel J Rigden
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
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Kelly D, Schratt G. Screening and Characterization of Functional circRNAs in Neuronal Cultures. Methods Mol Biol 2024; 2765:311-324. [PMID: 38381347 DOI: 10.1007/978-1-0716-3678-7_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
This chapter describes a methodology for the screening and characterization of functional circRNAs, particularly in the context of neural circuit development. Taking advantage of a primary rat neuron culture model of synaptogenesis, we propose a means of selecting from the plethora of circRNA species based on their expression levels, dendritic localization, conservation, and activity regulation. These candidates are then knocked down with RNAi approaches in a functional screen for their potential role in the formation and maturation of excitatory synapses.Upon identification of top candidates regulating synaptogenesis, we tie together different "Omics" approaches to explore the molecular mechanisms underlying the phenotypes observed upon circRNA knockdown. We utilized our EnrichMir algorithm to identify overrepresented miRNA binding sites in differentially expressed genes from polyA-RNA-seq following circRNA knockdown. Furthermore, our ScanMiR web tool allows for the miRNA binding prediction of reconstructed internal circular RNA sequences. Small-RNA sequencing is used to monitor changes in miRNA levels in the circRNA knockdown to complement results obtained from EnrichMiR. Finally, the experimental validation of promising miRNA-circRNA pairs sets the stage for in-depth biochemical exploration of the circRNA interactome and mechanism of action.
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Affiliation(s)
- Darren Kelly
- Lab of Systems Neuroscience, Institute for Neuroscience, Department of Health Science and Technology, Swiss Federal Institute of Technology ETH, Zurich, Switzerland
| | - Gerhard Schratt
- Lab of Systems Neuroscience, Institute for Neuroscience, Department of Health Science and Technology, Swiss Federal Institute of Technology ETH, Zurich, Switzerland.
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Chen W, Caiyun L, Yang Y, Xinwei H, Nan L, Jiaming Y, Huirong Y, Kai W, Liucheng Y. Circular RNA MTCL1 targets SMAD3 by sponging miR-145-5p for regulation of cell proliferation and migration in Hirschsprung's disease. Pediatr Surg Int 2023; 40:25. [PMID: 38127107 DOI: 10.1007/s00383-023-05621-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/15/2023] [Indexed: 12/23/2023]
Abstract
BACKGROUND Hirschsprung's disease (HSCR) is a congenital disorder resulting from abnormal development of the enteric nervous system (ENS). Given the complexity of its pathogenesis, it is important to investigate the role of epigenetic inheritance in its development. As Circ-MTCL1 is abundant in brain tissue and colon tissue, whether it has a significant part in the development of ENS is worth exploring. This study clarifies its role in HSCR and identifies the specific molecular mechanisms involved. METHODS Diseased and dilated segment colon tissues diagnosed as HSCR were collected for the assessment of gene expression levels using RT-PCR. EdU and CCK-8 assays were adopted to evaluate cell proliferation, and Transwell assay was adopted to assess cell migration. The interaction between Circ-MTCL1, miR-145-5p and SMAD3 was confirmed by dual luciferase reporter gene analysis, RT-PCR and Western blotting. RESULTS Circ-MTCL1 was down-regulated in the aganglionic colon tissues. The decreased expression of Circ-MTCL1 associated with a reduction in cell migration and proliferation. Bioinformatics analysis and cellular experiments confirmed its role might have been associated with the inhibition of miR-145-5p. MiR-145-5p was up-regulated in HSCR diseased segment colon tissues, exhibiting a negative correlation with Circ-MTCL1. Overexpression of miR-145-5p reversed the inhibition of cell migration and proliferation associated with Circ-MTCL1 down-regulation. The expression of SMAD3 was inhibited by miR-145-5p. The overexpression of SMAD3 eliminated the miR-145-5p-associated inhibition of cell migration and proliferation. Overexpression of miR-145-5p reversed the inhibitory effects of Circ-MTCL1 down-regulation-associated inhibition of cell migration and proliferation, while suppressing SMAD3 expression. Conversely, overexpression of SMAD3 counteracted the miR-145-5p-associated inhibition of cell migration and proliferation. CONCLUSIONS Circ-MTCL1 may function as a miR-145-5p sponge, regulating the expression of SMAD3 and influencing cell migration and proliferation, thus participating in the development of HSCR.
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Affiliation(s)
- Wang Chen
- Department of Pediatric Surgery, Zhujiang Hospital of Southern Medical University, Guangzhou, 510282, Guangdong, China
| | - Luo Caiyun
- Department of Pediatric Surgery, Zhujiang Hospital of Southern Medical University, Guangzhou, 510282, Guangdong, China
| | - Yang Yang
- Department of Pediatric Surgery, Zhujiang Hospital of Southern Medical University, Guangzhou, 510282, Guangdong, China
| | - Hou Xinwei
- Department of Pediatric Surgery, Zhujiang Hospital of Southern Medical University, Guangzhou, 510282, Guangdong, China
| | - Li Nan
- Department of Pediatric Surgery, Zhujiang Hospital of Southern Medical University, Guangzhou, 510282, Guangdong, China
| | - Yang Jiaming
- Department of Pediatric Surgery, Zhujiang Hospital of Southern Medical University, Guangzhou, 510282, Guangdong, China
| | - Yang Huirong
- Department of Pediatric Surgery, Zhujiang Hospital of Southern Medical University, Guangzhou, 510282, Guangdong, China
| | - Wu Kai
- Department of Pediatric Surgery, Zhujiang Hospital of Southern Medical University, Guangzhou, 510282, Guangdong, China.
| | - Yang Liucheng
- Department of Pediatric Surgery, Zhujiang Hospital of Southern Medical University, Guangzhou, 510282, Guangdong, China.
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